Energy Technology Data Exchange (ETDEWEB)
Becker, B.G.; Lane, D.A.; Max, N.L.
1995-03-01
Flow volumes are extended for use in unsteady (time-dependent) flows. The resulting unsteady flow volumes are the 3 dimensional analog of streamlines. There are few examples where methods other than particle tracing have been used to visualize time varying flows. Since particle paths can become convoluted in time there are additional considerations to be made when extending any visualization technique to unsteady flows. We will present some solutions to the problems which occur in subdivision, rendering, and system design. We will apply the unsteady flow volumes to a variety of field types including moving multi-zoned curvilinear grids.
Ethnic heterogeneity in the longitudinal effects of placental vascular blood flow on birthweight.
Misra, Vinod K; Hobel, Calvin J; Sing, Charles F
2008-01-01
Our goals were: (1) to estimate the longitudinal trends in uterine artery (UtArt) and umbilical artery (UmArt) resistance indices (RIs) in different ethnic strata; (2) to estimate time-dependent changes across gestation in the influence of variation in UtArt and UmArt RI on variation in birthweight in different ethnic strata; and (3) to determine the optimum set of UtArt and UmArt RIs for predicting birthweight in different ethnic strata. Analyses were carried out on data collected in a prospective study of 535 multiethnic gravidas recruited from the Cedars-Sinai Medical Center (Los Angeles, CA). Baseline maternal characteristics were recorded at time of entry into the study. UtArt and UmArt RIs were measured on 3 occasions during pregnancy (visit 1, 16-20 weeks' gestation; visit 2, 21-29 weeks' gestation; and visit 3, 30-36 weeks' gestation). The outcome for this study was gestational age-adjusted birthweight (aBW). The average UtArt and UmArt RI decreased steadily across gestation for all ethnicities. The average UtArt RI at each visit and the average rate of change between visits were not significantly different among the ethnicities. However, the UmArt RI measured at visit 3 and its rate of change in the last trimester were significantly different among the ethnic groups (P aBW only in Hispanic women, whereas the magnitude and rate of change of UmArt RI predicted aBW only in African American women. The most parsimonious combination of UtArt and UmArt RI measurements at visits 1, 2, and 3 that predicted statistically significant variation in aBW differed by ethnicity. The relationships between aBW and longitudinally collected measures of UtArt and UmArt RI depend on the context defined by ethnicity and time of measurement after adjusting for a parsimoniously selected subset of traditional risk factors.
Your Premature Baby: Low Birthweight
... many low-birthweight babies are born prematurely, many risk factors for having a low-birthweight baby are the same for preterm labor and ... risk for having a low-birthweight baby. Medical risk factors for having a low-birthweight baby Preterm labor . This is labor that starts ...
Birthweight and semen characteristics
DEFF Research Database (Denmark)
Olsen, Jørn; Bonde, Jens Peter; Basso, Olga
2000-01-01
A correlation between birthweight and sperm counts in adult life was anticipated because impaired fetal growth could impair replication of Sertoli cells produced in fetal life. Furthermore, it was expected that males born with a high birthweight might have impaired sperm production...... as they are expected to have been exposed to higher levels of oestrogen in fetal life. We examined these predictions by including midwives records for 296 Danish males that had taken part in studies on male fecundity for other reasons. The study provided no support for these expectations. If anything, males born...
Secular trends in birthweight.
Oken, Emily
2013-01-01
From the mid- to late 20th century, average birthweight increased in many countries, including the United States. However, more recent data now suggest that mean birthweight has begun to decline. The most recent US data indicate that in 2008, compared with 1990, about half as many babies were macrosomic at birth (≥5,000 g), whereas there was a 17% increase in low birthweight (gestation length and corresponding increases in rates of preterm and early term birth over the past several decades. However, available data suggest that fetal growth has also declined independent of gestational age at birth. Since 2000, rates of small for gestational age have increased, whereas rates of large for gestational age have decreased. Declines in birthweight and macrosomia are most likely largely explained by decreases in gestation length, itself caused by obstetric interventions, especially induction of labor and to a lesser extent elective cesarean delivery. However, it appears that fetal growth is also declining, at least in some settings, independent of gestation length. Reasons for this decline are as of yet unexplained and merit further investigation.
Vector Volume Flow in Arteriovenous Fistulas
DEFF Research Database (Denmark)
Hansen, Peter Møller; Heerwagen, Søren; Pedersen, Mads Møller;
2013-01-01
, but is very challenging due to the angle dependency of the Doppler technique and the anatomy of the fistula. The angle independent vector ultrasound technique Transverse Oscillation provides a new and more intuitive way to measure volume flow in an arteriovenous fistula. In this paper the Transverse...
Product formulas for volumes of flow polytopes
Meszaros, Karola
2011-01-01
Intrigued by the product formula prod_{i=1}^{n-2} C_i for the volume of the Chan-Robbins-Yuen polytope CRY_n, where C_i is the ith Catalan number, we construct a family of polytopes P_{m,n}, whose volumes are given by the product \\prod_{i=m+1}^{m+n-2}\\frac{1}{2i+1}{{m+n+i} \\choose {2i}}. The Chan-Robbins-Yuen polytope CRY_n coincides with P_{0,n-1}. Our construction of the polytopes P_{m,n} is an application of a systematic method we develop for expressing volumes of a class of flow polytopes as the number of certain triangular arrays. This method can also be used as a heuristic technique for constructing polytopes with combinatorial volumes. As an illustration of this we construct polytopes whose volumes equal the number of r-ary trees on n internal nodes, \\frac{1}{(r-1)n+1} {{rn} \\choose n}. Using triangular arrays we also express the volumes of flow polytopes as constant terms of formal Laurent series.
DEFF Research Database (Denmark)
Bakketeig, Leiv S.; Jacobsen, Geir; Skjærven, Rolv
2006-01-01
Previous studies have demonstrated the tendency to repeat gestational age and birthweight in successive pregnancies. Also, it has been shown that this tendency is associated with infant survival. Women tend to give birth to babies of a certain foetal age and size and if the outcome departs...... considerably from this age and weight, then the baby’s survival is reduced. This study focuses on which diseases or conditions that might lie behind this affected survival. Data were provided through linkages between three Danish health registries, namely the Danish Medical Birth Registry, the National...... Hospital Registry, and a Registry for Preventive Medicine. Such linkage is possible due to the use of unique ID-person numbers. The study was based on Danish births, 1981-1994. All 8 219 second order low birth weight (LBW) singleton births from that period were included, of whom 7 811 were live born...
Twin birth order, birthweight and birthweight discordance: any relationship
Directory of Open Access Journals (Sweden)
Onyiriuka A.N.
2010-12-01
Full Text Available Background: It is widely believed that in twin pairs, at birth, the first-born weigh more than the second-born but this concept has been challenged. Objective: To assess the truthfulness of this common concept that first-born twins are usually heavier than their second-born siblings at birth. Methods: In a series of 104 sets of live-born twins, the birth weights of first-born twins were compared with those of their second-born siblings, after controlling for gender. Their intra-pair birthweight differences were determined and twin pairs whose birthweight difference was 15% or more were designated as discordant. Results: Twin I was heavier than Twin II in 61.5% of cases while Twin II was heavier than Twin I in 28.9% of cases. Twins I and II had equal birthweights in 9.6% of cases. Comparing the mean birthweight of the first-born-male twin with that of second-born- male twin, it was 2515+427g (95% Confidence Interval, CI=2402-2628 versus 2432 +435g (95% CI=2321-2543 p>0.05. The mean birthweight of first-born-female twin was 2326+445g (95% CI=2214-2439 while that of the second-born-female twin was 2325+501g (95% CI=2197-2453 p>0.05. When the birthweight difference exceeded 750g, the probability that Twin I will be heavier than Twin II was 83.3% (5 of 6. Conclusion: Although the first-born twin was more often heavier than their second-born siblings, either could weigh more or less at birth. The larger the birthweight difference between growth-discordant twin pair, the greater the probability that the heavier twin would be delivered first
Prevention of low birthweight.
Alam, Dewan S
2009-01-01
Globally an estimated 20 million infants are born with low birthweight (LBW), of those over 18 million are born in developing countries. These LBW infants are at a disproportionately higher risk of mortality, morbidity, poor growth, impaired psychomotor and cognitive development as immediate outcomes, and are also disadvantaged as adults due to their greater susceptibility to type 2 diabetes, hypertension and coronary heart disease. Maternal malnutrition prior to and during pregnancy manifested by low bodyweight, short stature, inadequate energy intake during pregnancy and coexisting micronutrient deficiency are considered major determinants in developing countries where the burden is too high. LBW is a multifactorial outcome and its prevention requires a lifecycle approach and interventions must be continued for several generations. So far, most interventions are targeted during pregnancy primarily due to the increased nutritional demand and aggravations of already existing inadequacy in most women. Several individually successful interventions during pregnancy include balanced protein energy supplementation, several single micro-nutrients or more recently a mix of multiple micronutrients. Nutrition education has been successful in increasing the dietary intake of pregnant women but has had no effect on LBW. The challenge is to identify a community-specific intervention package. Current evidence supports intervention during pregnancy with increased dietary intakes including promotions of foods rich in micronutrients and micronutrient supplementation, preferably with a multiple micronutrient mix. Simultaneously a culturally appropriate educational component is required to address misconceptions about diet during pregnancy and childbirth including support for healthy pregnancy with promotion of antenatal and perinatal care services. While further research is needed to identify more efficacious interventions, an urgent public health priority would be to select and
Volume Flow in Arteriovenous Fistulas Using Vector Velocity Ultrasound
DEFF Research Database (Denmark)
Hansen, Peter Møller; Olesen, Jacob Bjerring; Pihl, Michael Johannes
2014-01-01
Volume flow in arteriovenous fistulas for hemodialysis was measured using the angle-independent ultrasound technique Vector Flow Imaging and compared with flow measurements using the ultrasound dilution technique during dialysis. Using an UltraView 800 ultrasound scanner (BK Medical, Herlev......, Denmark) with a linear transducer, 20 arteriovenous fistulas were scanned directly on the most superficial part of the fistula just before dialysis. Vector Flow Imaging volume flow was estimated with two different approaches, using the maximum and the average flow velocities detected in the fistula. Flow...
Volume Flow in Arteriovenous Fistulas Using Vector Velocity Ultrasound
DEFF Research Database (Denmark)
Hansen, Peter Møller; Olesen, Jacob Bjerring; Pihl, Michael Johannes;
2014-01-01
Volume flow in arteriovenous fistulas for hemodialysis was measured using the angle-independent ultrasound technique Vector Flow Imaging and compared with flow measurements using the ultrasound dilution technique during dialysis. Using an UltraView 800 ultrasound scanner (BK Medical, Herlev......, Denmark) with a linear transducer, 20 arteriovenous fistulas were scanned directly on the most superficial part of the fistula just before dialysis. Vector Flow Imaging volume flow was estimated with two different approaches, using the maximum and the average flow velocities detected in the fistula. Flow...
A liquid-independent volume flow measurement principle
Geers, L.F.G.; Volker, A.W.F.; Hunter, T.P.M.
2010-01-01
A novel flow measurement principle is presented enabling non-intrusive volume flow measurements of liquids in the ml/min range. It is based on an opto-acoustical time-of-flight principle, where the time interval is recorded in which a thermal label travels a known distance through a flow channel. Bi
Housing conditions as a social determinant of low birthweight and preterm low birthweight
Mario Vianna Vettore; Silvana Granado Nogueira da Gama; Gabriela de Almeida Lamarca; Arthur Orlando Corrêa Schilithz; Maria do Carmo Leal
2010-01-01
OBJECTIVE: To assess the relationship between housing conditions and low birthweight and preterm low birthweight among low-income women. METHODS: A case-control study was conducted with post-partum women living in the city of Rio de Janeiro, Southeast Brazil, in 2003-2005. Two groups of cases, low birthweight (n=96) and preterm low birthweight infants (n=68), were compared against normal weight term controls (n=393). Housing conditions were categorized into three levels: adequate, inadequate,...
Measurable inhomogeneities in stock trading volume flow
Cortines, A. A. G.; Riera, R.; Anteneodo, C.
2008-08-01
We investigate the statistics of volumes of shares traded in stock markets. We show that the stochastic process of trading volumes can be understood on the basis of a mixed Poisson process at the microscopic time level. The beta distribution of the second kind (also known as q-gamma distribution), that has been proposed to describe empirical volume histograms, naturally results from our analysis. In particular, the shape of the distribution at small volumes is governed by the degree of granularity in the trading process, while the exponent controlling the tail is a measure of the inhomogeneities in market activity. Furthermore, the present case furnishes empirical evidence of how power law probability distributions can arise as a consequence of a fluctuating intrinsic parameter.
FINITE VOLUME METHOD OF MODELLING TRANSIENT GROUNDWATER FLOW
Directory of Open Access Journals (Sweden)
N. Muyinda
2014-01-01
Full Text Available In the field of computational fluid dynamics, the finite volume method is dominant over other numerical techniques like the finite difference and finite element methods because the underlying physical quantities are conserved at the discrete level. In the present study, the finite volume method is used to solve an isotropic transient groundwater flow model to obtain hydraulic heads and flow through an aquifer. The objective is to discuss the theory of finite volume method and its applications in groundwater flow modelling. To achieve this, an orthogonal grid with quadrilateral control volumes has been used to simulate the model using mixed boundary conditions from Bwaise III, a Kampala Surburb. Results show that flow occurs from regions of high hydraulic head to regions of low hydraulic head until a steady head value is achieved.
Applications of texture mapping to volume and flow visualization
Energy Technology Data Exchange (ETDEWEB)
Max, N.; Crawfis, R.; Becker, B.
1995-05-01
The authors describe six visualization methods which take advantage of hardware polygon scan conversion, texture mapping, and compositing, to give interactive viewing of 3D scalar fields, and motion for 3D flows. For volume rendering, these are splatting of an optimized 3D reconstruction filter, and tetrahedral cell projection using a texture map to provide the exponential per pixel necessary for accurate opacity calculation. For flows, these are the above tetrahedral projection method for rendering the ``flow volume`` dyed after passing through a dye releasing polygon, ``splatting`` of cycled anisotropic textures to provide flow direction and motion visualization, splatting motion blurred particles to indicate flow velocity, and advecting a texture directly to show the flow motion. All these techniques are tailored to take advantage of existing graphics pipelines to produce interactive visualization tools.
Applications of texture mapping to volume and flow visualization
Energy Technology Data Exchange (ETDEWEB)
Max, N.; Crawfis, R.; Becker, B.
1995-05-01
The authors describe six visualization methods which take advantage of hardware polygon scan conversion, texture mapping, and compositing, to give interactive viewing of 3D scalar fields, and motion for 3D flows. For volume rendering, these are splatting of an optimized 3D reconstruction filter, and tetrahedral cell projection using a texture map to provide the exponential per pixel necessary for accurate opacity calculation. For flows, these are the above tetrahedral projection method for rendering the ``flow volume`` dyed after passing through a dye releasing polygon, ``splatting`` of cycled anisotropic textures to provide flow direction and motion visualization, splatting motion blurred particles to indicate flow velocity, and advecting a texture directly to show the flow motion. All these techniques are tailored to take advantage of existing graphics pipelines to produce interactive visualization tools.
Axially symmetric volume constrained anisotropic mean curvature flow
Palmer, Bennett
2011-01-01
We study the long time existence theory for a non local flow associated to a free boundary problem for a trapped non liquid drop. The drop has free boundary components on two horizontal plates and its free energy is anisotropic and axially symmetric. For axially symmetric initial surfaces with sufficiently large volume, we show that the flow exists for all time. Numerical simulations of the curvature flow are presented.
Humans, animals, robots: handling volumic data flows
Petrov, Valery
1999-08-01
Human visual system is properly suited for reliable and adequate volumetric perception of natural environment. Volumetric data flows coming from the outer physical space are easily acquired, transferred and processed by eye-brain system in real time. This relates also to the animals which use different complicate mechanisms of optical volumetric data acquisition and can navigate safely at high speeds. On the contrary machine vision systems utilizing currently the stereoscopic effect in attempt to achieve volumetric data presentation are very slow, bulky and in a way inelegantly devised. The stereoscopy itself seems can hardly organize the adequate, real time volumetric robot vision.
A volume-balance model for flow on porous media
Malaga, Carlos; Mandujano, Francisco; Becerra, Julian
2015-11-01
Volume-balance models are used by petroleum engineers for simulating multiphase and multicomponent flow phenomena in porous media and the extraction process in oil reservoirs. In these models, mass conservation equations and Darcy's law are supplemented by a balance condition for the pore and fluid volumes. This provides a pressure equation suitable for simulating a compressible flow within a compressible solid matrix. Here we present an alternative interpretation of the volume-balance condition that includes the advective transport within a consolidated porous media. We obtain a modified equation for the time evolution of the pressure field. Numerical tests for phase separation under gravity are presented for multiphase three dimensional flow in heterogeneous porous media. The authors acknowledge funding from Fondo Sectorial CONACYT-SENER grant number 42536 (DGAJ-SPI-34-170412-217).
Transcutaneous measurement of volume blood flow
Daigle, R. E.; Mcleod, F. D.; Miller, C. W.; Histand, M. B.; Wells, M. K.
1974-01-01
Blood flow velocity measurements, using Doppler velocimeter, are described. The ability to measure blood velocity using ultrasound is derived from the Doppler effect; the change in frequency which occurs when sound is reflected or transmitted from a moving target. When ultrasound of the appropriate frequency is transmitted through a moving blood stream, the blood cells act as point scatterers of ultrasonic energy. If this scattered ultrasonic energy is detected, it is found to be shifted in frequency according to the velocity of the blood cells, nu, the frequency of the incident sound, f sub o, the speed of sound in the medium, c, and the angle between the sound beam and the velocity vector, o. The relation describing this effect is known as the Doppler equation. Delta f = 2 f sub o x nu x cos alpha/c. The theoretical and experimental methods are evaluated.
Maximal expiratory flow volume curve in quarry workers.
Subhashini, Arcot Sadagopa; Satchidhanandam, Natesa
2002-01-01
Maximal Expiratory Flow Volume (MEFV) curves were recorded with a computerized Spirometer (Med Spiror). Forced Vital Capacity (FVC), Forced Expiratory Volumes (FEV), mean and maximal flow rates were obtained in 25 quarry workers who were free from respiratory disorders and 20 healthy control subjects. All the functional values are lower in quarry workers than in the control subject, the largest reduction in quarry workers with a work duration of over 15 years, especially for FEF75. The effects are probably due to smoking rather than dust exposure.
Control volume based modelling of compressible flow in reciprocating machines
DEFF Research Database (Denmark)
Andersen, Stig Kildegård; Thomsen, Per Grove; Carlsen, Henrik
2004-01-01
conservation laws for mass, energy, and momentum applied to a staggered mesh consisting of two overlapping strings of control volumes. Loss mechanisms can be included directly in the governing equations of models by including them as terms in the conservation laws. Heat transfer, flow friction......, and multidimensional effects must be calculated using empirical correlations; correlations for steady state flow can be used as an approximation. A transformation that assumes ideal gas is presented for transforming equations for masses and energies in control volumes into the corresponding pressures and temperatures...
Housing conditions as a social determinant of low birthweight and preterm low birthweight
Directory of Open Access Journals (Sweden)
Mario Vianna Vettore
2010-12-01
Full Text Available OBJECTIVE: To assess the relationship between housing conditions and low birthweight and preterm low birthweight among low-income women. METHODS: A case-control study was conducted with post-partum women living in the city of Rio de Janeiro, Southeast Brazil, in 2003-2005. Two groups of cases, low birthweight (n=96 and preterm low birthweight infants (n=68, were compared against normal weight term controls (n=393. Housing conditions were categorized into three levels: adequate, inadequate, and highly inadequate. Covariates included sociodemographic and anthropometric characteristics, risk behaviors, violence, anxiety, satisfaction during pregnancy, obstetric history and prenatal care. RESULTS: Poor housing conditions was independently associated with low birthweight (inadequate - OR 2.3 [1.1;4.6]; highly inadequate - OR 7.6 [2.1;27.6] and preterm low birthweight (inadequate - OR 2.2 [1.1;4.3]; highly inadequate - OR 7.6 [2.4;23.9] and factors associated with outcomes were inadequate prenatal care and previous preterm birth. Low income and low maternal body mass index remained associated with low birthweight. CONCLUSIONS: Poor housing conditions were associated with low birthweight and preterm low birthweight.
Ambient air pollution and low birthweight
DEFF Research Database (Denmark)
Pedersen, Marie; Giorgis-Allemand, Lise; Bernard, Claire
2013-01-01
BACKGROUND: Ambient air pollution has been associated with restricted fetal growth, which is linked with adverse respiratory health in childhood. We assessed the effect of maternal exposure to low concentrations of ambient air pollution on birthweight. METHODS: We pooled data from 14 population...... air pollutants and traffic during pregnancy is associated with restricted fetal growth. A substantial proportion of cases of low birthweight at term could be prevented in Europe if urban air pollution was reduced. FUNDING: The European Union....
Control volume based modelling of compressible flow in reciprocating machines
DEFF Research Database (Denmark)
Andersen, Stig Kildegård; Thomsen, Per Grove; Carlsen, Henrik
2004-01-01
, and multidimensional effects must be calculated using empirical correlations; correlations for steady state flow can be used as an approximation. A transformation that assumes ideal gas is presented for transforming equations for masses and energies in control volumes into the corresponding pressures and temperatures...
Microfluidic flow switching design using volume of fluid model.
Chein, Reiyu; Tsai, S H
2004-03-01
In this study, a volume of fluid (VOF) model was employed for microfluidic switch design. The VOF model validity in predicting the interface between fluid streams with different viscosities co-flowing in a microchannel was first verified by experimental observation. It was then extended to microfluidic flow switch design. Two specific flow switches, one with a guided fluid to one of five desired outlet ports, and another with a guided fluid flows into one, two, or three outlet ports equally distributed along the outlet channel of a Y-shaped channel. The flow switching was achieved by controlling the flow rate ratios between tested and buffer fluids. The numerical results showed that the VOF model could successfully predict the flow switching phenomena in these flow switches. The numerical results also showed that the flow rate ratio required for flow switching depends on the viscosity ratio between the tested and buffer fluids. The numerical simulation was verified by experimental study and the agreement was good.
Internet traffic load balancing using dynamic hashing with flow volume
Jo, Ju-Yeon; Kim, Yoohwan; Chao, H. Jonathan; Merat, Francis L.
2002-07-01
Sending IP packets over multiple parallel links is in extensive use in today's Internet and its use is growing due to its scalability, reliability and cost-effectiveness. To maximize the efficiency of parallel links, load balancing is necessary among the links, but it may cause the problem of packet reordering. Since packet reordering impairs TCP performance, it is important to reduce the amount of reordering. Hashing offers a simple solution to keep the packet order by sending a flow over a unique link, but static hashing does not guarantee an even distribution of the traffic amount among the links, which could lead to packet loss under heavy load. Dynamic hashing offers some degree of load balancing but suffers from load fluctuations and excessive packet reordering. To overcome these shortcomings, we have enhanced the dynamic hashing algorithm to utilize the flow volume information in order to reassign only the appropriate flows. This new method, called dynamic hashing with flow volume (DHFV), eliminates unnecessary flow reassignments of small flows and achieves load balancing very quickly without load fluctuation by accurately predicting the amount of transferred load between the links. In this paper we provide the general framework of DHFV and address the challenges in implementing DHFV. We then introduce two algorithms of DHFV with different flow selection strategies and show their performances through simulation.
Lagrangian Transport Through Surfaces in Volume-Preserving Flows
Karrasch, Daniel
2015-01-01
Advective transport of scalar quantities through surfaces is of fundamental importance in many scientific applications. From the Eulerian perspective of the surface it can be quantified by the well-known integral of the flux density. The recent development of highly accurate semi-Lagrangian methods for solving scalar conservation laws and of Lagrangian approaches to coherent structures in turbulent (geophysical) fluid flows necessitate a new approach to transport from the (Lagrangian) material perspective. We present a Lagrangian framework for calculating transport of conserved quantities through a given surface in $n$-dimensional, fully aperiodic, volume-preserving flows. Our approach does not involve any dynamical assumptions on the surface or its boundary.
Paternal Age as a Risk Factor for Low Birthweight
National Research Council Canada - National Science Library
Reichman, Nancy E; Teitler, Julien O
2006-01-01
... birthweight were found. Conclusions. We identified paternal age as an independent risk factor for low birthweight in the US urban population, suggesting that more attention needs to be paid to ...
Motion by Volume Preserving Mean Curvature Flow Near Cylinders
Hartley, David
2012-01-01
Center manifold analysis can be used in order to investigate the stability of the stationary solutions of various PDEs. This can be done by considering the PDE as an ODE between certain Banach spaces and linearising about the stationary solution. Here we investigate the volume preserving mean curvature flow using such a technique. We will consider surfaces with boundary contained within two parallel planes such that the surface meets these planes orthogonally. With this set up the stationary solution is a cylinder. We will find that for initial surfaces that are sufficiently close to a cylinder the flow will exist for all time and converge to a cylinder exponentially. In particular, we show that there exists global solutions to the flow that converge to a cylinder, which are initially non-axially symmetric. A similar case where the initial surfaces are compact without boundary has previously been investigated by Escher and Simonett (1998).
Reduction of Volume-preserving Flows on an n-dimensional Manifold
Institute of Scientific and Technical Information of China (English)
Yong-ai Zheng; De-bin Huang; Zeng-rong Liu
2003-01-01
A geometric reduction procedure for volume-preserving flows with a volume-preserving symmetry on an n-dimensional manifold is obtained. Instead of the coordinate-dependent theory and the concrete coordinate transformation, we show that a volume-preserving flow with a one-parameter volume-preserving symmetry on an n-dimensional manifold can be reduced to a volume-preserving flow on the corresponding (n - 1)-dimensional quotient space. More generally, if it admits an r-parameter volume-preserving commutable symmetry, then the reduced flow preserves the corresponding (n - r)-dimensional volume form.
The Yang-Mills gradient flow in finite volume
Fodor, Zoltan; Kuti, Julius; Nogradi, Daniel; Wong, Chik Him
2012-01-01
The Yang-Mills gradient flow is considered on the four dimensional torus T^4 for SU(N) gauge theory coupled to N_f flavors of massless fermions in arbitrary representations. The small volume dynamics is dominated by the constant gauge fields. The expectation value of the field strength tensor squared is calculated for positive flow time t by treating the non-zero gauge modes perturbatively and the zero modes exactly. The finite volume correction to the infinite volume result is found to contain both algebraic and exponential terms. The leading order result is then used to define a one parameter family of running coupling schemes in which the coupling runs with the linear size of the box. The new scheme is tested numerically in SU(3) gauge theory coupled to N_f = 4 flavors of massless fundamental fermions. The calculations are performed at several lattice spacings with a controlled continuum extrapolation. The continuum result agrees with the perturbative 2-loop prediction for small renormalized coupling as ex...
Childhood acute lymphoblastic leukaemia and birthweight
DEFF Research Database (Denmark)
Roman, Eve; Lightfoot, Tracy; Smith, Alexandra G
2013-01-01
BACKGROUND: Heavy birthweight is one of the few established risk factors for childhood acute lymphoblastic leukaemia (ALL). To provide new insight into this relationship, particularly at the extremes ( 4500 g), we pooled data from three of the largest childhood cancer case...
Application of vector finite volume method for electromagnetic flow simulation
Energy Technology Data Exchange (ETDEWEB)
Takata, T.; Murashige, R.; Matsumoto, T.; Yamaguchi, A. [Osaka Univ., Suita, Osaka (Japan)
2011-07-01
A vector finite volume method (VFVM) has been developed for an electromagnetic flow analysis. In the VFVM, the governing equations of magnetic flux density and electric field intensity are solved separately so as to reduce the computational cost caused by an iterative procedure that is required to satisfy the solenoidal condition. In the present paper, a suppression of temperature fluctuation of liquid sodium after a T-junction has also been investigated with a simplified two dimensional numerical analysis by adding an obstacle (turbulence promoter) or a magnetic field after the junction. (author)
Fluid mechanics experiments in oscillatory flow. Volume 1: Report
Seume, J.; Friedman, G.; Simon, T. W.
1992-01-01
Results of a fluid mechanics measurement program in oscillating flow within a circular duct are presented. The program began with a survey of transition behavior over a range of oscillation frequency and magnitude and continued with a detailed study at a single operating point. Such measurements were made in support of Stirling engine development. Values of three dimensionless parameters, Re(sub max), Re(sub w), and A(sub R), embody the velocity amplitude, frequency of oscillation and mean fluid displacement of the cycle, respectively. Measurements were first made over a range of these parameters which included operating points of all Stirling engines. Next, a case was studied with values of these parameters that are representative of the heat exchanger tubes in the heater section of NASA's Stirling cycle Space Power Research Engine (SPRE). Measurements were taken of the axial and radial components of ensemble-averaged velocity and rms-velocity fluctuation and the dominant Reynolds shear stress, at various radial positions for each of four axial stations. In each run, transition from laminar to turbulent flow, and its reverse, were identified and sufficient data was gathered to propose the transition mechanism. Models of laminar and turbulent boundary layers were used to process the data into wall coordinates and to evaluate skin friction coefficients. Such data aids in validating computational models and is useful in comparing oscillatory flow characteristics to those of fully-developed steady flow. Data were taken with a contoured entry to each end of the test section and with flush square inlets so that the effects of test section inlet geometry on transition and turbulence are documented. Volume 1 contains the text of the report including figures and supporting appendices. Volume 2 contains data reduction program listings and tabulated data (including its graphical presentation).
Volume Displacement Effects in Bubble-laden Flows
Cihonski, Andrew; Finn, Justin; Apte, Sourabh
2012-11-01
When a few bubbles are entrained in a traveling vortex ring, it has been shown that even at extremely low volume loadings, their presence can significantly affect the structure of the vortex core (Sridhar & Katz 1999). A typical Euler-Lagrange point-particle model with two-way coupling for this dilute system, wherein the bubbles are assumed subgrid and momentum point-sources are used to model their effect on the flow, is shown to be unable to accurately capture the experimental trends of bubble settling location and vortex distortion for a range of bubble parameters and vortex strengths. The bubbles experience a significant amount of drag, lift, added mass, pressure, and gravity forces. However, these forces are in balance of each other, as the bubbles reach a mean settling location away from the vortex core. Accounting for fluid volume displacement due to bubble motion, using a model termed as volumetric coupling, experimental trends on vortex distortion and bubble settling location are well captured. The fluid displacement effects are studied by introducing a notion of a volumetric coupling force, the net force on the fluid due to volumetric coupling, which is found to be dominant even at the low volume loadings investigated here.
Finite-volume WENO scheme for viscous compressible multicomponent flows
Coralic, Vedran; Colonius, Tim
2014-01-01
We develop a shock- and interface-capturing numerical method that is suitable for the simulation of multicomponent flows governed by the compressible Navier-Stokes equations. The numerical method is high-order accurate in smooth regions of the flow, discretely conserves the mass of each component, as well as the total momentum and energy, and is oscillation-free, i.e. it does not introduce spurious oscillations at the locations of shockwaves and/or material interfaces. The method is of Godunov-type and utilizes a fifth-order, finite-volume, weighted essentially non-oscillatory (WENO) scheme for the spatial reconstruction and a Harten-Lax-van Leer contact (HLLC) approximate Riemann solver to upwind the fluxes. A third-order total variation diminishing (TVD) Runge-Kutta (RK) algorithm is employed to march the solution in time. The derivation is generalized to three dimensions and nonuniform Cartesian grids. A two-point, fourth-order, Gaussian quadrature rule is utilized to build the spatial averages of the reconstructed variables inside the cells, as well as at cell boundaries. The algorithm is therefore fourth-order accurate in space and third-order accurate in time in smooth regions of the flow. We corroborate the properties of our numerical method by considering several challenging one-, two- and three-dimensional test cases, the most complex of which is the asymmetric collapse of an air bubble submerged in a cylindrical water cavity that is embedded in 10% gelatin. PMID:25110358
Energy Technology Data Exchange (ETDEWEB)
Hong, Hyun Sook; Cha, Jang Gyu; Park, Seong Jin; Joh, Joon Hee; Park, Jai Soung; Kim, Dae Ho; Lee, Hae Kyung; Ahn, Hyun Cheol [Soonchunhyang University Bucheon Hospital, Bucheon (Korea, Republic of)
2003-09-15
Vertebrobasilar ischemia has been attributed to a reduction of net vertebral artery flow volume. This study was to establish the reference values for the flow volume of the vertebral artery using color Doppler sonography in the normal Korea adults. Thirty five normal Korea adults without any underlying disease including hypertension, hyperlipidemia, diabetes, heart disease, obesity (body mas index>30), or carotid artery stenosis was included. There were 17 males and 18 females, age ranged from 20 to 53 years (average=32.86 years). Flow velocities and vessel diameters were recorded in the intertransverse (V2) segment, usually at C5-6 level, bilaterally. The flow volume (Q) was calculated. (Q=time averaged mean velocity x cross sectional area of vessel) A lower Flow velocity and smaller vessel diameter were measured on the right side compared to those of the left side, resulting in a lower flow volume. The calculated flow volumes using the equation were 77.0 +- 39.7 ml/min for the right side and 127.6 +- 71.0 ml/min for the left side (p=0.0001) while the net vertebral artery flow volume was 204.6 +- 81.8 ml/min. Decrease in the vertebral artery flow volume was statistically significant with advanced age. (r=-0.36, p=0.032). Vertebral artery blood flow volume was 191.20 +- 59.19 ml/min in male, and 217.28 +- 98.67 ml/min in female (p=0.6). The normal range for the net vertebral artery flow volume defined by the 5th to 95th percentiles was between 110.06 and 364.1 ml/min. The normal range for the net vertebral artery flow volume was between 110.06 and 364.1 ml/min. Vertebral artery flow volume decreased with the increase of age. However, gender did not affect the blood flow volume.
Customised birthweight standards accurately predict perinatal morbidity
Figueras, Francesc; Figueras, Josep; Meler, Eva; Eixarch, Elisenda; Coll, Oriol; Gratacos, Eduard; Gardosi, Jason; Carbonell, Xavier
2007-01-01
Objective Fetal growth restriction is associated with adverse perinatal outcome but is often not recognised antenatally, and low birthweight centiles based on population norms are used as a proxy instead. This study compared the association between neonatal morbidity and fetal growth status at birth as determined by customised birthweight centiles and currently used centiles based on population standards. Design Retrospective cohort study. Setting Referral hospital, Barcelona, Spain. Patients A cohort of 13 661 non‐malformed singleton deliveries. Interventions Both population‐based and customised standards for birth weight were applied to the study cohort. Customised weight centiles were calculated by adjusting for maternal height, booking weight, parity, ethnic origin, gestational age at delivery and fetal sex. Main outcome measures Newborn morbidity and perinatal death. Results The association between smallness for gestational age (SGA) and perinatal morbidity was stronger when birthweight limits were customised, and resulted in an additional 4.1% (n = 565) neonates being classified as SGA. Compared with non‐SGA neonates, this newly identified group had an increased risk of perinatal mortality (OR 3.2; 95% CI 1.6 to 6.2), neurological morbidity (OR 3.2; 95% CI 1.7 to 6.1) and non‐neurological morbidity (OR 8; 95% CI 4.8 to 13.6). Conclusion Customised standards improve the prediction of adverse neonatal outcome. The association between SGA and adverse outcome is independent of the gestational age at delivery. PMID:17251224
Finite volume methods for submarine debris flows and generated waves
Kim, Jihwan; Løvholt, Finn; Issler, Dieter
2016-04-01
Submarine landslides can impose great danger to the underwater structures and generate destructive tsunamis. Submarine debris flows often behave like visco-plastic materials, and the Herschel-Bulkley rheological model is known to be appropriate for describing the motion. In this work, we develop numerical schemes for the visco-plastic debris flows using finite volume methods in Eulerian coordinates with two horizontal dimensions. We provide parameter sensitivity analysis and demonstrate how common ad-hoc assumptions such as including a minimum shear layer depth influence the modeling of the landslide dynamics. Hydrodynamic resistance forces, hydroplaning, and remolding are all crucial terms for underwater landslides, and are hence added into the numerical formulation. The landslide deformation is coupled to the water column and simulated in the Clawpack framework. For the propagation of the tsunamis, the shallow water equations and the Boussinesq-type equations are employed to observe how important the wave dispersion is. Finally, two cases in central Norway, i.e. the subaerial quick clay landslide at Byneset in 2012, and the submerged tsunamigenic Statland landslide in 2014, are both presented for validation. The research leading to these results has received funding from the Research Council of Norway under grant number 231252 (Project TsunamiLand) and the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement 603839 (Project ASTARTE).
Fluid mechanics experiments in oscillatory flow. Volume 2: Tabulated data
Seume, J.; Friedman, G.; Simon, T. W.
1992-01-01
Results of a fluid mechanics measurement program in oscillating flow within a circular duct are presented. The program began with a survey of transition behavior over a range of oscillation frequency and magnitude and continued with a detailed study at a single operating point. Such measurements were made in support of Stirling engine development. Values of three dimensionless parameters, Re sub max, Re sub w, and A sub R, embody the velocity amplitude, frequency of oscillation, and mean fluid displacement of the cycle, respectively. Measurements were first made over a range of these parameters that are representative of the heat exchanger tubes in the heater section of NASA's Stirling cycle Space Power Research Engine (SPRE). Measurements were taken of the axial and radial components of ensemble-averaged velocity and rms velocity fluctuation and the dominant Reynolds shear stress, at various radial positions for each of four axial stations. In each run, transition from laminar to turbulent flow, and its reverse, were identified and sufficient data was gathered to propose the transition mechanism. Volume 2 contains data reduction program listings and tabulated data (including its graphics).
Birthweight-specific risk factors for necrotising enterocolitis.
Palmer, S R; Thomas, S.J.; Cooke, R W; Low, D C; Fysh, W J; Murphy, J F; Gandy, G. M.; Gamsu, H R
1987-01-01
In a multicentre case-control study of necrotising enterocolitis risk factors were found to vary with birthweight of cases. In very low birthweight cases the risk factors identified were those associated with prolonged or recurrent hypoxia (recurrent apnoea, respiratory distress, assisted ventilation, and umbilical artery catheterisation). In heavier birthweight infants the risk factors were, in contrast, related to hypoxia at birth (low 1 minute Apgar score and endotracheal intubation at bir...
Maternal recall of birthweight and birth size in Entebbe, Uganda.
Lule, Swaib A; Webb, Emily L; Ndibazza, Juliet; Nampijja, Margaret; Muhangi, Lawrence; Akello, Florence; Kakande, Muhammed; Kizindo, Robert; Elliott, Alison M
2012-12-01
To assess the reliability of maternally recalled birthweight and size in Entebbe, Uganda. The study population comprised 404 mothers, who were participants in the Entebbe Mother and Baby Study (EMaBS). Mothers were recruited to EMaBS during antenatal care, maternal characteristics were recorded during pregnancy, and birthweight was recorded at delivery. Four to seven years after delivery, mothers were asked to recall the child's birthweight and size. Their responses were compared with the birthweight recorded in the EMaBS database. Of 404 interviewed mothers, 303 (75%) were able to give an estimate of birthweight and for 265 of these EMaBS data on recorded birthweights were available. Women who were educated and whose children had low birth order were more likely to be able to give an estimate: 37 (14%) recalled the exact recorded birthweight; a further 52 (20%) were accurate to within 0.1 kg of the recorded weight. On average, mothers overestimated birthweight by 0.06 kg (95% CI: 0.00-0.13 kg, P = 0.04). Recalled and recorded birthweights showed moderate agreement with an intraclass correlation coefficient of 0.64. Four hundered mothers gave an estimate of birth size: the sensitivity and specificity of recalled birth size for classifying low birthweight were 76% (95% CI: 50-93%) and 70% (95% CI: 65-75%), respectively. Mothers' recall of birthweight was not precise but in absence of other data, recall of birthweight and size may have some value in epidemiological studies in these settings. © 2012 Blackwell Publishing Ltd.
DEFF Research Database (Denmark)
Jensen, Jonas; Olesen, Jacob Bjerring; Stuart, Matthias Bo
2016-01-01
A method for vector velocity volume flow estimation is presented, along with an investigation of its sources of error and correction of actual volume flow measurements. Volume flow errors are quantified theoretically by numerical modeling, through flow phantom measurements, and studied in vivo...... than circular, vessel area and correcting the ultrasound beam for being off-axis, gave a significant (p = 0.008) reduction in error from 31.2% to 24.3%. The error is relative to the Ultrasound Dilution Technique, which is considered the gold standard for volume flow estimation for dialysis patients....... This paper investigates errors from estimating volumetric flow using a commercial ultrasound scanner and the common assumptions made in the literature. The theoretical model shows, e.g. that volume flow is underestimated by 15%, when the scan plane is off-axis with the vessel center by 28% of the vessel...
Relative risks of low birthweight in Scotland 1980-2.
Pickering, R.M.
1987-01-01
Routinely collected data for 187,000 Scottish singleton livebirths in 1980-2 were used to relate the risk of birthweight below 2500 g, 2000 g, 1500 g, and 1000 g to sex of infant and nine maternal factors. Maternal height was a major predictor of birthweight below 2500g but was less important in predicting birthweight in the lower intervals. A history of prenatal death and spontaneous abortion was important for all four intervals and was associated with most extreme risks for birthweight belo...
Defining small-for-gestational-age: prescriptive versus descriptive birthweight standards
Hoftiezer, L.; Hukkelhoven, C.W.P.M.; Hogeveen, M.; Straatman, H.M.; Lingen, R.A. van
2016-01-01
Descriptive population-based birthweight standards possess low sensitivity in detecting infants with growth impairment. A prescriptive birthweight standard based on a 'healthy' subpopulation without risk factors for intrauterine growth restriction might be superior. We created two birthweight
de Kieviet, Jorrit F.; Zoetebier, Lydia; van Elburg, Ruurd M.; Vermeulen, R. Jeroen; Oosterlaan, Jaap
2012-01-01
Aim: The aim of this article was to clarify the impact and consequences of very preterm birth (born less than 32wks of gestation) and/or very low birthweight ([VLBW], weighing less than 1500g) on brain volume development throughout childhood and adolescence. Method: The computerized databases PubMed, Web of Knowledge, and EMBASE were searched for…
Explicit volume-preserving and symplectic integrators for trigonometric polynomial flows
Quispel, G R W
2003-01-01
We introduce explicit volume-preserving and symplectic integrators for the case of generalized trigonometric polynomial flows. The method is demonstrated using the Arter flow, and computational trials are conducted using a 4-dimensional vector field.
Reference birthweight range for multiple birth neonates in Japan
Directory of Open Access Journals (Sweden)
Kato Noriko
2004-02-01
Full Text Available Abstract Background A reference range for the birthweight of multiple births neonates is necessary for the assessment for intrauterine growth. Methods Pairs of multiple births were identified by birthplace, the ages of the parents, gestational age, and the year and month of birth. We studied a total of 32,232 livebirth-livebirth pairs of twins, 1894 triplet live births, and 206 quadruplet live births. Results The median birthweight of males, taking gestational age into account, was ca. 0.05 kg–0.1 kg heavier than that of females. Compared to singleton neonates, the median birthweight of twins was ca. 0.15 kg smaller at the gestational age of 34 weeks, increasing to ca. 0.5 kg at 42 weeks of gestation. As for birth order, the mean birthweight of the first-born twin was heavier than that of the second-born. The standard deviation of birthweight was larger for second-born twins. The birthweight of twins from multiparous mothers was greater than those from primiparous mothers. The median birthweight according to gestational age was found to be the greatest in twins, lower in triplets and the lowest in quadruplets. In triplets, the 50th percentile was 0.08 kg heavier in boys than for girls. Conclusion Our results can be used for assessment of birthweight of multiple births in Japan.
The Impact of Birthweight and Adolescent Health on Educational Attainment
Brekke, Idunn; Reisel, Liza
2017-01-01
This article examines the relationship between birthweight, adolescent health (general health and psychological distress) and high school completion in Norway, using survey data linked to longitudinal registry data (n = 5,354). The findings show that the positive association between birthweight and high school completion can be attributed to…
New Dutch reference curves for birthweight by gestational age
Visser, Gerard H. A.; Eilers, Paul H. C.; Elferink-Stinkens, Patty M.; Merkus, Hans M. W. M.; Wit, Jan M.
2009-01-01
Objective: To construct new Dutch reference curves for birthweight by parity, sex and ethnic background. Design: Retrospective nationwide study, Material and methods: Reference curves for birthweight were constructed using the LMS model and were based on 176,000 singleton births in the Netherlands i
Headlights on tobacco road to low birthweight outcomes
DEFF Research Database (Denmark)
Bache, Stefan Holst; Dahl, Christian Møller; Kristensen, Johannes Tang
2013-01-01
Low birthweight outcomes are associated with considerable social and economic costs, and therefore the possible determinants of low birthweight are of great interest. One such determinant which has received considerable attention is maternal smoking. From an economic perspective this is in part d...
Factors affecting prenatal sonographic estimation of weight in extremely low birthweight infants.
Townsend, R R; Filly, R A; Callen, P W; Laros, R K
1988-04-01
Because critical management decisions are based on sonographic estimation of fetal weight in fetuses less than 1000 g, we sought to evaluate the accuracy of birthweight prediction in this range and to identify factors affecting this accuracy. Fetal weight was estimated using several published methods in 53 fetuses with birthweights less than 1000 g. Standard deviations greater than 12.3% indicate more random error in the sonographic weight prediction than has been reported in higher weight groups. No statistically significant differences were found between patient groups with decreased, normal, or increased amniotic fluid volume or portable examination. There was a trend toward lower mean deviation (2.9 vs 6.0%) and standard deviation (8.9 vs. 15.0%) in studies with scan quality judged "good" compared with "poor" based on ability to visualize anatomic landmarks.
Predictive macrosomia birthweight thresholds for adverse maternal and neonatal outcomes.
Wang, Dan; Zhu, Li; Zhang, Shulian; Wu, Xueqin; Wang, Xiaoli; Lv, Qin; Gan, Dongmei; Liu, Ling; Li, Wen; Zhou, Qin; Lu, Jiarong; He, Haiying; Wang, Jimei; Xin, Hua; Li, Zhankui; Chen, Chao
2016-12-01
We examined the predictive macrosomia birthweight thresholds for adverse maternal and neonatal outcomes. This was a multicenter, retrospective cohort study conducted in China. We selected 178 709 singletons weighing ≥2500 g with gestational age 37-44 weeks. We categorized macrosomia with two gradations (4000-4499 g and ≥4500 g) and compared them with a normosomic reference group of infants with birthweight 2500-3999 g. The risks of obstetric and neonatal complications increased when infants had a birthweight of ≥4000 g. The rates of infant mortality, Apgar score ≤3 at 5 min, respiratory and neurological disorders rose significantly among neonates weighing ≥4500 g. A definition of macrosomia as birthweight ≥4000 g could be beneficial as an indicator of obstetric and newborn complications, and birthweight ≥4500 g might be predictive of severe infant morbidity and mortality risk.
Control Volume Analysis, Entropy Balance and the Entropy Production in Flow Systems
Niven, Robert K.; Noack, Bernd R.
2014-01-01
This chapter concerns "control volume analysis", the standard engineering tool for the analysis of flow systems, and its application to entropy balance calculations. Firstly, the principles of control volume analysis are enunciated and applied to flows of conserved quantities (e.g. mass, momentum, energy) through a control volume, giving integral (Reynolds transport theorem) and differential forms of the conservation equations. Several definitions of steady state are discussed. The concept of...
Can flow-volume loops be used to diagnose exercise induced laryngeal obstructions?
DEFF Research Database (Denmark)
Christensen, Pernille M; Maltbæk, Niels; Jørgensen, Inger M
2013-01-01
BACKGROUND: Pre- and post-exercise flow-volume loops are often recommended as an easy non-invasive method for diagnosing or excluding exercise-induced laryngeal obstructions in patients with exercise-related respiratory symptoms. However, at present there is no evidence for this recommendation....... AIMS: To compare physician evaluated pre- and post-exercise flow-volume loops and flow data with laryngoscopic findings during exercise. METHODS: Data from 100 consecutive exercise tests with continuous laryngoscopy during the test were analysed. Laryngoscopic images were compared...... with the corresponding pre- and post-exercise flow-volume loops assessed by four separate physicians and with data from the loops (forced inspiratory flow (FIF) at 25% vs. FIF at 75% of forced inspiratory vital capacity (FIVC), forced expiratory flow at 50% of forced expiratory volume vs. FIF at 50% of FIVC, and FIVC vs...
Low birthweight in Mexico: a systematic review.
Buekens, Pierre; Canfield, Caitlin; Padilla, Nicolas; Lara Lona, Elia; Lozano, Rafael
2013-01-01
There is abundant literature on the birth outcomes of women of Mexican origin living in the United States, but in most cases it does not refer to data available in Mexico. We conducted a systematic review of available data regarding low birthweight (LBW) rates in Mexico. We searched official online Mexican administrative data bases and four literature databases: OVID (Global Health), EMBASE, PubMed, and Bireme. The following inclusion criteria were used: (1) study is in English, Spanish, or Portuguese; (2) study presents data regarding LBW or birthweight distribution in Mexico; (3) study defines LBW as either 7.9%). States at low altitudes (<50 m) had LBW rates lower than the median, with the exception of Yucatán state. The systematic literature review identified 22 hospital-based studies and three household interview surveys that met our inclusion criteria. The hospital-based LBW rates were relatively similar to the birth certificate data and slightly lower than survey data. Data on LBW rates are available in Mexico. They should be analyzed further and used for comparative studies.
Accuracy and Sources of Error for an Angle Independent Volume Flow Estimator
DEFF Research Database (Denmark)
Jensen, Jonas; Olesen, Jacob Bjerring; Hansen, Peter Møller
2014-01-01
This paper investigates sources of error for a vector velocity volume flow estimator. Quantification of the estima tor’s accuracy is performed theoretically and investigated in vivo . Womersley’s model for pulsatile flow is used to simulate velo city profiles and calculate volume flow errors in c...... % underestimated volume flow according to the simulation. Volume flow estimates were corrected for the beam being off- axis, but was not able to significantly decrease the error rel ative to measurements with the reference method.......This paper investigates sources of error for a vector velocity volume flow estimator. Quantification of the estima tor’s accuracy is performed theoretically and investigated in vivo . Womersley’s model for pulsatile flow is used to simulate velo city profiles and calculate volume flow errors....... A BK Medical UltraView 800 ultrasound scanner with a 9 MHz linear array transducer is used to obtain Vector Flow Imaging sequences of a superficial part of the fistulas. Cross-sectional diameters of each fistu la are measured on B-mode images by rotating the scan plane 90 degrees. The major axis...
Jensen, Jonas; Olesen, Jacob Bjerring; Stuart, Matthias Bo; Hansen, Peter Møller; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt
2016-08-01
A method for vector velocity volume flow estimation is presented, along with an investigation of its sources of error and correction of actual volume flow measurements. Volume flow errors are quantified theoretically by numerical modeling, through flow phantom measurements, and studied in vivo. This paper investigates errors from estimating volumetric flow using a commercial ultrasound scanner and the common assumptions made in the literature. The theoretical model shows, e.g. that volume flow is underestimated by 15%, when the scan plane is off-axis with the vessel center by 28% of the vessel radius. The error sources were also studied in vivo under realistic clinical conditions, and the theoretical results were applied for correcting the volume flow errors. Twenty dialysis patients with arteriovenous fistulas were scanned to obtain vector flow maps of fistulas. When fitting an ellipsis to cross-sectional scans of the fistulas, the major axis was on average 10.2mm, which is 8.6% larger than the minor axis. The ultrasound beam was on average 1.5mm from the vessel center, corresponding to 28% of the semi-major axis in an average fistula. Estimating volume flow with an elliptical, rather than circular, vessel area and correcting the ultrasound beam for being off-axis, gave a significant (p=0.008) reduction in error from 31.2% to 24.3%. The error is relative to the Ultrasound Dilution Technique, which is considered the gold standard for volume flow estimation for dialysis patients. The study shows the importance of correcting for volume flow errors, which are often made in clinical practice.
Trends in birthweight between 1857 and 1883, in Melbourne, Australia.
Morley, Ruth; McCalman, Janet; Carlin, John
2003-07-01
Epidemiological evidence suggesting that subjects with lower birthweight have an increased risk of adult cardiovascular disease has led to increased interest in factors influencing birthweight. We have documented large changes in mean birthweight over a relatively short historical period from 1857 to 1883. Mean birthweight declined progressively from 7.9 lb (3.6 kg) in the period 1857-63 to 6.9 lb (3.1 kg) in 1874-78, then rose to 7.5 lb (3.4 kg) for the period 1879-83. We found the expected relationships between infant birthweight and maternal age, parity and marital status, and identified an association between birthweight and maternal country of birth. However, neither temporal changes in recorded maternal characteristics nor external economic indicators for the colony explained the trends in birthweight. From historical information, we believe that the explanation for our findings lies primarily with the increasing poverty, disease, mental illness, alcohol abuse and criminal activity among women admitted to the hospital between 1860 and the mid-1870s, and improvements from around 1880, when old housing was replaced and prostitutes were moved out of the area. Our findings highlight the difficulty of capturing lifestyle factors using routinely collected data, and the need for historical expertise when examining historical data.
A Robust volume conservative divergence-free ISPH framework for free-surface flow problems
Pahar, Gourabananda; Dhar, Anirban
2016-10-01
This study presents a Volume Conservative approach for resolving volume conservation issue in divergence-free incompressible Smoothed Particle Hydrodynamics (ISPH). Irregular free surface deformation may introduce error in volume computation, which has a cascading effect over time. Proposed correction decreases this numerical compressibility to a minimal value. The correction is obtained directly by solving Navier-Stokes momentum equation. Consequently, the framework does not require any parametric study for mixed source/sink term or iterative solution of pressure Poisson equations. The correction is implemented on four different types of flow: (a) pressurized flow in a closed box, (b) dambreak flow, (c) flow through porous block, (d) lock-exchange flow of immiscible fluids (both free-surface and pressurized flow). All four scenarios are shown to have minimal error compared to pure divergence-free ISPH.
The control of volume flow heating gases oh coke plant
Directory of Open Access Journals (Sweden)
Kostúr Karol
2003-12-01
Full Text Available The contribution deals with mixture and coke gases volume quantity determination for coke battery in term of their optimal redistribution at single blocks in consideration of accurate observance of corresponding technological temperature.
Wall, M A; Olson, D; Bonn, B A; Creelman, T; Buist, A S
1982-02-01
Reference standards of lung function was determined in 176 healthy North American Indian children (94 girls, 82 boys) 7 to 18 yr of age. Spirometry, maximal expiratory flow volume curves, and peak expiratory flow rate were measured using techniques and equipment recommended by the American Thoracic Society. Standing height was found to be an accurate predictor of lung function, and prediction equations for each lung function variable are presented using standing height as the independent variable. Lung volumes and expiratory flow rates in North American Indian children were similar to those previously reported for white and Mexican-American children but were greater than those in black children. In both boys and girls, lung function increased in a curvilinear fashion. Volume-adjusted maximal expiratory flow rates after expiring 50 or 75% of FVC tended to decrease in both sexes as age and height increased. Our maximal expiratory flow volume curve data suggest that as North American Indian children grow, lung volume increases at a slightly faster rate than airway size does.
A calculation procedure for viscous flow in turbomachines, volume 2
Khalil, J.; Tabakoff, W.
1980-01-01
Turbulent flow within turbomachines having arbitrary blade geometries is examined. Effects of turbulence are modeled using two equations, one expressing the development of the turbulence kinetic energy and the other its dissipation rate. To account for complicated blade geometries, the flow equations are formulated in terms of a nonorthogonal boundary fitted coordinate system. The analysis is applied to a radial inflow turbine. The solution obtained indicates the severity of the complex interaction mechanism that occurs between the different flow regimes (i.e., boundary layers, recirculating eddies, separation zones, etc.). Comparison with nonviscous flow solutions tend to justify strongly the inadequacy of using the latter with standard boundary layer techniques to obtain viscous flow details within turbomachine rotors. Capabilities and limitations of the present method of analysis are discussed.
National Aeronautics and Space Administration — Thorleaf Research, Inc. has demonstrated feasibility in Phase I and now proposes a Phase II effort to develop a miniaturized high flow, low dead-volume...
low birthweight babies: socio-demographic and obstetric ...
African Journals Online (AJOL)
2002-10-01
Oct 1, 2002 ... mothers (aged below 20 years) and older mothers of low birthweight ( ... have unfavourable socio-demographic and obstetric factors like ... having less formal education, being unemployed and having obstetric risks for poor.
Adult glucose metabolism in extremely birthweight-discordant monozygotic twins
DEFF Research Database (Denmark)
Frost, M; Petersen, I; Brixen, K
2012-01-01
Low birthweight (BW) is associated with increased risk of type 2 diabetes. We compared glucose metabolism in adult BW-discordant monozygotic (MZ) twins, thereby controlling for genetic factors and rearing environment.......Low birthweight (BW) is associated with increased risk of type 2 diabetes. We compared glucose metabolism in adult BW-discordant monozygotic (MZ) twins, thereby controlling for genetic factors and rearing environment....
Seals/Secondary Fluid Flows Workshop 1997; Volume I
Hendricks, Robert C. (Editor)
2006-01-01
The 1997 Conference provided discussions and data on (a) program overviews, (b) developments in seals and secondary air management systems, (c) interactive seals flows with secondary air or fluid flows and powerstream flows, (d) views of engine externals and limitations, (e) high speed engine research sealing needs and demands, and (f) a short course on engine design development margins. Sealing concepts discussed include, mechanical rim and cavity seals, leaf, finger, air/oil, rope, floating-brush, floating-T-buffer, and brush seals. Engine externals include all components of engine fluid systems, sensors and their support structures that lie within or project through the nacelle. The clean features of the nacelle belie the minefield of challenges and opportunities that lie within. Seals; Secondary air flows; Rotordynamics; Gas turbine; Aircraft; CFD; Testing; Turbomachinery
Two-Dimensional Turbulent Separated Flow. Volume 1
1985-06-01
of detached turbulent boundary layers, even when the sign of U is changed to account for mean backflows. Thus, earlier researchers, such as Kuhn and...Turbulent Shear Layer," Third Symposium on Turbulent Shear Flows, pp. 16.23-16.29. Hillier, R., Latour , M.E.M.P., and Cherry, N.J. (1983), "Unsteady...344. Kuhn , G.D. and Nielsen, J.N. (1971), "An Analytical Method for Calculating Turbulent Separated Flows Due to Adverse Pressure Gradients
A calculation procedure for viscous flow in turbomachines, volume 1
Khalil, I.; Tabakoff, W.
1979-01-01
A method for analyzing the nonadiabatic viscous flow through turbomachine rotors is presented. The field analysis is based upon the numerical integration of the full incompressible stream function vorticity form of the Navier-Stokes equations, together with the energy equation, over the rotor blade-to-blade stream channels. The numerical code used to solve the governing equations employs a nonorthogonal boundary fitted coordinate system that suits the most complicated blade geometries. A numerical scheme is used to carry out the necessary integration of the elliptic governing equations. The flow characteristics within the rotor of a radial inflow turbine are investigated over a wide range of operating conditions. The calculated results are compared to existing experimental data. The flow in a radial compressor is analyzed in order to study the behavior of viscous flow in diffusing cascades. The results are compared qualitatively to known experimental trends. The solution obtained provides insight into the flow phenomena in this type of turbomachine. It is concluded that the method of analysis is quite general and gives a good representation of the actual flow behavior within turbomachine passages.
Volume of the steady-state space of financial flows in a monetary stock-flow-consistent model
Hazan, Aurélien
2016-01-01
We show that a steady-state stock-flow consistent macroeconomic model can be represented as a Constraint Satisfaction Problem (CSP). The set of solutions is a polytope, which volume depends on the constraints applied and reveals the potential fragility of the economic circuit, with no need to specify the dynamics. Several methods to compute the volume are compared, inspired by operations research methods and the analysis of metabolic networks, both exact and approximate. We also introduce a random transaction matrix, and study the particular case of linear flows with respect to money stocks.
Energy Technology Data Exchange (ETDEWEB)
Fukami, Tadanori [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Sato, Hidenori [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Wu, Jin [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Lwin, Thet-Thet- [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Yuasa, Tetsuya [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Kawano, Satoru [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Iida, Keiji [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Akatsuka, Takao [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Hontani, Hidekata [Department of Computer Science and Engineering, Nagoya Institute of Technology, Aichi 466-8555 (Japan); Takeda, Tohoru [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Tamura, Masao [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Yokota, Hiroshi [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan)
2007-07-21
Our study aimed to quantitatively evaluate blood flow in the left ventricle (LV) of apical hypertrophic cardiomyopathy (APH) by combining wall thickness obtained from cardiac magnetic resonance imaging (MRI) and myocardial perfusion from single-photon emission computed tomography (SPECT). In this study, we considered paired MRI and myocardial perfusion SPECT from ten patients with APH and ten normals. Myocardial walls were detected using a level set method, and blood flow per unit myocardial volume was calculated using 3D surface-based registration between the MRI and SPECT images. We defined relative blood flow based on the maximum in the whole myocardial region. Accuracies of wall detection and registration were around 2.50 mm and 2.95 mm, respectively. We finally created a bull's-eye map to evaluate wall thickness, blood flow (cardiac perfusion) and blood flow per unit myocardial volume. In patients with APH, their wall thicknesses were over 10 mm. Decreased blood flow per unit myocardial volume was detected in the cardiac apex by calculation using wall thickness from MRI and blood flow from SPECT. The relative unit blood flow of the APH group was 1/7 times that of the normals in the apex. This normalization by myocardial volume distinguishes cases of APH whose SPECT images resemble the distributions of normal cases.
Surveillance for hemodialysis access stenosis: usefulness of ultrasound vector volume flow
DEFF Research Database (Denmark)
Brandt, Andreas Hjelm; Jensen, Jonas; Hansen, Kristoffer L.
2016-01-01
Purpose: To investigate if ultrasound vector-flow imaging (VFI) is equal to the reference method ultrasound dilution technique (UDT) in estimating volume flow and changes over time in arteriovenous fistulas (AVFs) for hemodialysis. Materials and methods: From January 2014 to January 2015, patients......, and regression analysis. Repeated measurements and precision analysis were used for reproducibility determination. Results: Precision measurements for UDT and VFI were 32% and 20%, respectively (p = 0.33). Average volume flow measured with UDT and VFI were 1161 mL/min (±778 mL/min) and 1213 mL/min (±980 m...
Thinking outside the curve, part I: modeling birthweight distribution
Directory of Open Access Journals (Sweden)
Charnigo Richard
2010-07-01
Full Text Available Abstract Background Greater epidemiologic understanding of the relationships among fetal-infant mortality and its prognostic factors, including birthweight, could have vast public health implications. A key step toward that understanding is a realistic and tractable framework for analyzing birthweight distributions and fetal-infant mortality. The present paper is the first of a two-part series that introduces such a framework. Methods We propose describing a birthweight distribution via a normal mixture model in which the number of components is determined from the data using a model selection criterion rather than fixed a priori. Results We address a number of methodological issues, including how the number of components selected depends on the sample size, how the choice of model selection criterion influences the results, and how estimates of mixture model parameters based on multiple samples from the same population can be combined to produce confidence intervals. As an illustration, we find that a 4-component normal mixture model reasonably describes the birthweight distribution for a population of white singleton infants born to heavily smoking mothers. We also compare this 4-component normal mixture model to two competitors from the existing literature: a contaminated normal model and a 2-component normal mixture model. In a second illustration, we discover that a 6-component normal mixture model may be more appropriate than a 4-component normal mixture model for a general population of black singletons. Conclusions The framework developed in this paper avoids assuming the existence of an interval of birthweights over which there are no compromised pregnancies and does not constrain birthweights within compromised pregnancies to be normally distributed. Thus, the present framework can reveal heterogeneity in birthweight that is undetectable via a contaminated normal model or a 2-component normal mixture model.
Giant Volume Change of Active Gels under Continuous Flow
2014-04-21
communication17 of BZ droplets and chemical self-organiza- tion,18 the properties and potential of self-oscillating gels in a microfluidic system have yet to be...active gels driven by the Belousov−Zhabotinsky reaction. These results demon- strate that microfluidics offers a useful and facile experimental...soft materials and microfluidic systems. ■ INTRODUCTION This paper reports the use of a continuous reactant flow in a microfluidic system to achieve
Energy Technology Data Exchange (ETDEWEB)
Acar, Murat [Department of Radiology, Faculty of Medicine, Afyon Kocatepe University, Kirmizi Hastane, 03200 Afyon (Turkey)]. E-mail: drmacar@hotmail.com; Degirmenci, Bumin [Department of Radiology, Faculty of Medicine, Afyon Kocatepe University, Kirmizi Hastane, 03200 Afyon (Turkey); Yucel, Aylin [Department of Radiology, Faculty of Medicine, Afyon Kocatepe University, Kirmizi Hastane, 03200 Afyon (Turkey); Albayrak, Ramazan [Department of Radiology, Faculty of Medicine, Afyon Kocatepe University, Kirmizi Hastane, 03200 Afyon (Turkey); Haktanir, Alpay [Department of Radiology, Faculty of Medicine, Afyon Kocatepe University, Kirmizi Hastane, 03200 Afyon (Turkey); Yaman, Mehmet [Department of Neurology, Faculty of Medicine, Afyon Kocatepe University, 03200 Afyon (Turkey)
2005-05-01
Introduction: The aim of this study was to compare the measurements of vertebral artery (VA) systolic flow velocity and flow volume for diagnosis of vertebrobasilar insufficiency (VBI). Material and methods: We examined 96 patients who were referred for evaluation of VBI. Net vertebral artery flow volume and mean systolic flow velocity were determined by using color duplex sonography. We had grouped the patients into three according to VA flow volume: group 1 was consisted of patients with severely damped VA flow volume (lower than 120 mL/min), group 2 was consisted of patients with moderately damped VA flow volume (120-200 mL/min), group 3 was consisted of patients with normal VA flow volume (>200 mL/min). The mean systolic flow velocities in each group were compared by one-way ANOVA. Results: Mean VA systolic flow velocities of groups 1, 2 and 3 were 32 {+-} 12, 42 {+-} 10 and 46 {+-} 8 cm/s, respectively. Mean VA systolic flow velocity in group 1 was significantly lower than that of group 2 (P = 0.001). However, there were no significant differences between VA systolic flow velocities in groups 2 and 3 (P = 0.2). Conclusions: According to our findings, measurement of volume in addition to velocity is more valuable in detection of moderately damped VA flow volumes in diagnosis of VBI.
A Derivation of the Nonlocal Volume-Averaged Equations for Two-Phase Flow Transport
Directory of Open Access Journals (Sweden)
Gilberto Espinosa-Paredes
2012-01-01
Full Text Available In this paper a detailed derivation of the general transport equations for two-phase systems using a method based on nonlocal volume averaging is presented. The local volume averaging equations are commonly applied in nuclear reactor system for optimal design and safe operation. Unfortunately, these equations are limited to length-scale restriction and according with the theory of the averaging volume method, these fail in transition of the flow patterns and boundaries between two-phase flow and solid, which produce rapid changes in the physical properties and void fraction. The non-local volume averaging equations derived in this work contain new terms related with non-local transport effects due to accumulation, convection diffusion and transport properties for two-phase flow; for instance, they can be applied in the boundary between a two-phase flow and a solid phase, or in the boundary of the transition region of two-phase flows where the local volume averaging equations fail.
Doppler sonography of diabetic feet: Quantitative analysis of blood flow volume
Energy Technology Data Exchange (ETDEWEB)
Seo, Young Lan; Kim, Ho Chul; Choi, Chul Soon; Yoon, Dae Young; Han, Dae Hee; Moon, Jeung Hee; Bae, Sang Hoon [Hallym University College of Medicine, Seoul (Korea, Republic of)
2002-09-15
To analyze Doppler sonographic findings of diabetic feet by estimating the quantitative blood flow volume and by analyzing waveform on Doppler. Doppler sonography was performed in thirty four patients (10 diabetic patients with foot ulceration, 14 diabetic patients without ulceration and 10 normal patients as the normal control group) to measure the flow volume of the arteries of the lower extremities (posterior and anterior tibial arteries, and distal femoral artery. Analysis of doppler waveforms was also done to evaluate the nature of the changed blood flow volume of diabetic patients, and the waveforms were classified into triphasic, biphasic-1, biphasic-2 and monophasic patterns. Flow volume of arteries in diabetic patients with foot ulceration was increased witha statistical significance when compared to that of diabetes patients without foot ulceration of that of normal control group (P<0.05). Analysis of Doppler waveform revealed that the frequency of biphasic-2 pattern was significantly higher in diabetic patients than in normal control group(p<0.05). Doppler sonography in diabetic feet showed increased flow volume and biphasic Doppler waveform, and these findings suggest neuropathy rather than ischemic changes in diabetic feet.
Flow Visualization Techniques for CDF using Volume Rendering
Energy Technology Data Exchange (ETDEWEB)
Crawfis, R.A.; Shen, H-W.; Max, N.
2000-07-10
As simulations have migrated towards three-dimensions, new tools for examining the resulting complex datasets have been required. Much progress has been achieved in the area of scientific visualization towards this goal. However, most of the research has focused on the representation and understanding of a single scalar field. Some nice results have been achieved for vector or flow fields. This paper reviews several of these techniques, organizes them by their approach and complexity and presents some observations on their benefits and limitations. Several example images are used to highlight the character of these techniques.
Variability in venom volume, flow rate and duration in defensive stings of five scorpion species.
van der Meijden, Arie; Coelho, Pedro; Rasko, Mykola
2015-06-15
Scorpions have been shown to control their venom usage in defensive encounters, depending on the perceived threat. Potentially, the venom amount that is injected could be controlled by reducing the flow speed, the flow duration, or both. We here investigated these variables by allowing scorpions to sting into an oil-filled chamber, and recording the accreting venom droplets with high-speed video. The size of the spherical droplets on the video can then be used to calculate their volume. We recorded defensive stings of 20 specimens representing 5 species. Significant differences in the flow rate and total expelled volume were found between species. These differences are likely due to differences in overall size between the species. Large variation in both venom flow speed and duration are described between stinging events of single individuals. Both venom flow rate and flow duration correlate highly with the total expelled volume, indicating that scorpions may control both variables in order to achieve a desired end volume of venom during a sting.
Directory of Open Access Journals (Sweden)
Santiago Jr. A.T.
1997-01-01
Full Text Available We determined the effect of acute extracellular fluid volume changes on saline flow through 4 gut segments (ileocolonic, ileal, ileocolonic sphincter and proximal colon, perfused at constant pressure in anesthetized dogs. Two different experimental protocols were used: hypervolemia (iv saline infusion, 0.9% NaCl, 20 ml/min, volume up to 5% body weight and controlled hemorrhage (up to a 50% drop in mean arterial pressure. Mean ileocolonic flow (N = 6 was gradually and significantly decreased during the expansion (17.1%, P<0.05 and expanded (44.9%, P<0.05 periods while mean ileal flow (N = 7 was significantly decreased only during the expanded period (38%, P<0.05. Mean colonic flow (N = 7 was decreased during expansion (12%, P<0.05 but returned to control levels during the expanded period. Mean ileocolonic sphincter flow (N = 6 was not significantly modified. Mean ileocolonic flow (N = 10 was also decreased after hemorrhage (retracted period by 17% (P<0.05, but saline flow was not modified in the other separate circuits (N = 6, 5 and 4 for ileal, ileocolonic sphincter and colonic groups, respectively. The expansion effect was blocked by atropine (0.5 mg/kg, iv both on the ileocolonic (N = 6 and ileal (N = 5 circuits. Acute extracellular fluid volume retraction and expansion increased the lower gastrointestinal resistances to saline flow. These effects, which could physiologically decrease the liquid volume being supplied to the colon, are possible mechanisms activated to acutely balance liquid volume deficit and excess.
Energy Technology Data Exchange (ETDEWEB)
J. K. Hartwell; J. B. Walter; D. M. Scates; M. W. Drigert
2007-05-01
The AGR-1 experiment is a fueled multiple-capsule irradiation experiment being conducted in the Advanced Test Reactor (ATR) in support of the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program. A flow experiment conducted during the AGR-1 irradiation provided data that included the effect of flow rate changes on the decay of a short-lived radionuclide (23Ne). This data has been analyzed to determine the capsule-specific downstream transport volume through which the capsule effluents must pass before arrival at the fission product monitoring system spectrometers. These resultant transport volumes when coupled with capsule outlet flow rates determine the transport times from capsule-to-detector. In this work an analysis protocol is developed and applied in order to determine capsule-specific transport volumes to precisions of better than +/- 7%.
Energy Technology Data Exchange (ETDEWEB)
None
1996-11-01
Volume VI of the documentation for the Phase I Data Analysis Task performed in support of the current Regional Flow Model, Transport Model, and Risk Assessment for the Nevada Test Site Underground Test Area Subproject contains the groundwater flow model data. Because of the size and complexity of the model area, a considerable quantity of data was collected and analyzed in support of the modeling efforts. The data analysis task was consequently broken into eight subtasks, and descriptions of each subtask's activities are contained in one of the eight volumes that comprise the Phase I Data Analysis Documentation.
Determinants of Birthweight Outcomes: Quantile Regressions Based on Panel Data
DEFF Research Database (Denmark)
Bache, Stefan Holst; Dahl, Christian Møller; Kristensen, Johannes Tang
regression framework in order to control for heterogeneity and to infer conclusions about causality across the entire birthweight distribution. We obtain estimation results for maternal smoking and other interesting determinants, applying these to data obtained from Aarhus University Hospital, Skejby...... to the possibility that smoking habits can be influenced through policy conduct. It is widely believed that maternal smoking reduces birthweight; however, the crucial difficulty in estimating such effects is the unobserved heterogeneity among mothers. We consider extensions of three panel data models to a quantile...... and significance of prenatal smoking. Controlling for unobserved effects does not change the fact that smoking reduces birthweight, but it shows that the effect is primarily a problem in the left tail of the distribution on a slightly smaller scale....
Meng, Yiqing; Lucas, Gary P.
2017-05-01
This paper presents the design and implementation of an inductive flow tomography (IFT) system, employing a multi-electrode electromagnetic flow meter (EMFM) and novel reconstruction techniques, for measuring the local water velocity distribution in water continuous single and multiphase flows. A series of experiments were carried out in vertical-upward and upward-inclined single phase water flows and ‘water continuous’ gas-water and oil-gas-water flows in which the velocity profiles ranged from axisymmetric (single phase and vertical-upward multiphase flows) to highly asymmetric (upward-inclined multiphase flows). Using potential difference measurements obtained from the electrode array of the EMFM, local axial velocity distributions of the continuous water phase were reconstructed using two different IFT reconstruction algorithms denoted RT#1, which assumes that the overall water velocity profile comprises the sum of a series of polynomial velocity components, and RT#2, which is similar to RT#1 but which assumes that the zero’th order velocity component may be replaced by an axisymmetric ‘power law’ velocity distribution. During each experiment, measurement of the local water volume fraction distribution was also made using the well-established technique of electrical resistance tomography (ERT). By integrating the product of the local axial water velocity and the local water volume fraction in the cross section an estimate of the water volumetric flow rate was made which was compared with a reference measurement of the water volumetric flow rate. In vertical upward flows RT#2 was found to give rise to water velocity profiles which are consistent with the previous literature although the profiles obtained in the multiphase flows had relatively higher central velocity peaks than was observed for the single phase profiles. This observation was almost certainly a result of the transfer of axial momentum from the less dense dispersed phases to the water
Profiling river surface velocities and volume flow estimation with bistatic UHF RiverSonde radar
Barrick, D.; Teague, C.; Lilleboe, P.; Cheng, R.; Gartner, J.; ,
2003-01-01
From the velocity profiles across the river, estimates of total volume flow for the four methods were calculated based on a knowledge of the bottom depth vs position across the river. It was found that the flow comparisons for the American River were much closer, within 2% of each other among all of the methods. Sources of positional biases and anomalies in the RiverSonde measurement patterns along the river were identified and discussed.
DEFF Research Database (Denmark)
Andersen, Stig Kildegård; Carlsen, Henrik; Thomsen, Per Grove
2006-01-01
We present an approach for modelling unsteady, primarily one-dimensional, compressible flow. The conservation laws for mass, energy, and momentum are applied to a staggered mesh of control volumes and loss mechanisms are included directly as extra terms. Heat transfer, flow friction......, and multidimensional effects are calculated using empirical correlations. Transformations of the conservation equations into new variables, artificial dissipation for dissipating acoustic phenomena, and an asymmetric interpolation method for minimising numerical diffusion and non physical temperature oscillations...
Schuette, W H; Shackney, S E; Plowman, F A; Tipton, H W; Smith, C A; MacCollum, M A
1984-11-01
A multibeam optical detection system has been developed with a high optical efficiency, achieved through a reduction in the number of optical interfaces employed in the system. This reduction is made possible by a combination of employing simple lenses, gluing the objective lens directly upon the face of the flow cuvette and the extraction of only one fluorescence signal from each laser beam. A modified flow chamber is also described that includes fluidic resistance elements for the elimination of most of the electric shielding normally associated with electronic cell volume measurements.
Directory of Open Access Journals (Sweden)
Claire E Kelly
Full Text Available BACKGROUND: Adolescents born extremely preterm (EP; <28 weeks' gestation and/or extremely low birthweight (ELBW; <1000 g experience high rates of visual impairments, however the potential neural correlates of visual impairments in EP/ELBW adolescents require further investigation. This study aimed to: 1 compare optic radiation and primary visual cortical structure between EP/ELBW adolescents and normal birthweight controls; 2 investigate associations between perinatal factors and optic radiation and primary visual cortical structure in EP/ELBW adolescents; 3 investigate associations between optic radiation and primary visual cortical structure in EP/ELBW adolescents and the odds of impaired vision. METHODS: 196 EP/ELBW adolescents and 143 controls underwent magnetic resonance imaging at a mean age of 18 years. Optic radiations were delineated using constrained spherical deconvolution based probabilistic tractography. Primary visual cortices were segmented using FreeSurfer software. Diffusion tensor variables and tract volume of the optic radiations, as well as volume, surface area and thickness of the primary visual cortices, were estimated. RESULTS: Axial, radial and mean diffusivities within the optic radiations, and primary visual cortical thickness, were higher in the EP/ELBW adolescents than controls. Within EP/ELBW adolescents, postnatal corticosteroid exposure was associated with altered optic radiation diffusion values and lower tract volume, while decreasing gestational age at birth was associated with increased primary visual cortical volume, area and thickness. Furthermore, decreasing optic radiation fractional anisotropy and tract volume, and increasing optic radiation diffusivity in EP/ELBW adolescents were associated with increased odds of impaired vision, whereas primary visual cortical measures were not associated with the odds of impaired vision. CONCLUSIONS: Optic radiation and primary visual cortical structure are altered in
Energy Technology Data Exchange (ETDEWEB)
Watanabe, Taro, E-mail: watanabe_t@qe.see.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita-shi, Osaka 565-7895 (Japan); Takata, Takashi, E-mail: takata.takashi@jaea.go.jp [Japan Atomic Energy Agency, 4002 Narita-chou, Oarai-machi, Higashi-Ibaraki-gun, Ibaraki 331-1393 (Japan); Yamaguchi, Akira, E-mail: yamaguchi@n.t.u-tokyo.ac.jp [Graduate School of Engineering, The University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-1188 (Japan)
2017-03-15
Highlights: • Thin liquid film flow under CCFL was modeled and coupled with the VOF method. • The difference of the liquid flow rate in experiments of CCFL was evaluated. • The proposed VOF method can quantitatively predict CCFL with low computational cost. - Abstract: Countercurrent flow limitation (CCFL) in a heat transfer tube at a steam generator (SG) of pressurized water reactor (PWR) is one of the important issues on the core cooling under a loss of coolant accident (LOCA). In order to improve the prediction accuracy of the CCFL characteristics in numerical simulations using the volume of fluid (VOF) method with less computational cost, a thin liquid film flow in a countercurrent flow is modeled independently and is coupled with the VOF method. The CCFL characteristics is evaluated analytically in condition of a maximizing down-flow rate as a function of a void fraction or a liquid film thickness considering a critical thickness. Then, we have carried out numerical simulations of a countercurrent flow in a vertical tube so as to investigate the CCFL characteristics and compare them with the previous experimental results. As a result, it has been concluded that the effect of liquid film entrainment by upward gas flux will cause the difference in the experiments.
Maternal mid-pregnancy lipids and birthweight
Mudd, Lanay M.; Holzman, Claudia B.; Evans, Rhobert W.
2015-01-01
Objective To describe associations among maternal lipids and birthweight and to determine whether pre-pregnancy body mass index (BMI) modifies these associations. Design Cohort Study. Setting Multiple communities in Michigan, USA. Population Participants were a sub-cohort of women from the multi-community Pregnancy Outcomes and Community Health (POUCH) study (1998–2004). Methods Maternal total cholesterol, high-density lipoprotein (HDLc), and low-density lipoprotein (LDLc) cholesterol, and triglycerides were assessed at 16–27 weeks’ gestation. Women were classified as having normal (<25 kg/m2) or overweight/obese (≥25 kg/m2) pre-pregnancy BMI. Main Outcome Measures Sex- and gestational-age-specific BWz-score. Results Regression models examined associations among lipids (low: 1st quartile, referent: middle quartiles, high: 4th quartile) and BWz-scores for the total sample and stratified by pre-pregnancy BMI. In adjusted analyses (n=1207), low HDLc was associated with lower BWz-score (β=−0.23, 95%CI: −0.40 to −0.06) while high triglycerides was associated with higher BWz-score (β=0.23, 95%CI: 0.06–0.41). Once stratified by pre-pregnancy BMI, low total cholesterol was associated with lower BWz-score in normal BMI women (β= −0.25, 95%CI: −0.47 to −0.03), while in overweight/obese BMI women, high HDLc was inversely (β= −0.29, 95%CI: −0.54 to −0.04) and high triglycerides was directly associated with BWz-score (β=0.32, 95%CI: 0.07– 0.54). Removing women with gestational diabetes/hypertensive disorders did not alter the results. Conclusions The associations among maternal lipids and BWz-score vary by lipid measure and pre-pregnancy BMI. Future work should examine whether lipids and pre-pregnancy BMI make unique contributions to the fetal programming of disease. PMID:25912426
Syrakos, Alexandros; Alexandrou, Andreas N
2016-01-01
We extend our recent work on the creeping flow of a Bingham fluid in a lid-driven cavity, to the study of inertial effects, using a finite volume method and the Papanastasiou regularisation of the Bingham constitutive model [J. Rheology 31 (1987) 385-404]. The finite volume method used belongs to a very popular class of methods for solving Newtonian flow problems, which use the SIMPLE algorithm to solve the discretised set of equations, and have matured over the years. By regularising the Bingham constitutive equation it is easy to extend such a solver to Bingham flows since all that this requires is to modify the viscosity function. This is a tempting approach, since it requires minimum programming effort and makes available all the existing features of the mature finite volume solver. On the other hand, regularisation introduces a parameter which controls the error in addition to the grid spacing, and makes it difficult to locate the yield surfaces. Furthermore, the equations become stiffer and more difficu...
Nonlinear Effects in Osmotic Volume Flows of Electrolyte Solutions through Double-Membrane System
Slezak, A.; Jasik-Slezak, J.; Grzegorczyn, S.; Slezak-Prochazka, I.
2012-01-01
The results of experimental study of volume osmotic flows in a double-membrane system are presented in this article. The double-membrane system consists of two membranes (M-u, M-d) oriented in horizontal planes and three identical compartments (u, m, d), containing unstirred binary or ternary ionic
Nonlinear Effects in Osmotic Volume Flows of Electrolyte Solutions through Double-Membrane System
Slezak, A.; Jasik-Slezak, J.; Grzegorczyn, S.; Slezak-Prochazka, I.
2012-01-01
The results of experimental study of volume osmotic flows in a double-membrane system are presented in this article. The double-membrane system consists of two membranes (M-u, M-d) oriented in horizontal planes and three identical compartments (u, m, d), containing unstirred binary or ternary ionic
Fabric inlet stratifiers for solar tanks with different volume flow rates
DEFF Research Database (Denmark)
Andersen, Elsa; Furbo, Simon
2006-01-01
in the centre of a glass tank (400 x 400 x 900 mm). The forced volume flow rate is in the range of 6 – 10 l/min, and water enters the stratification pipe from the bottom of the tank. The thermal behaviour of the stratification pipes is investigated for different realistic operation conditions...
Nonlinear Effects in Osmotic Volume Flows of Electrolyte Solutions through Double-Membrane System
Slezak, A.; Jasik-Slezak, J.; Grzegorczyn, S.; Slezak-Prochazka, I.
The results of experimental study of volume osmotic flows in a double-membrane system are presented in this article. The double-membrane system consists of two membranes (M-u, M-d) oriented in horizontal planes and three identical compartments (u, m, d), containing unstirred binary or ternary ionic
Brookes, G B; Fairfax, A J
1982-06-01
Chronic obstructive lesions of the upper airways such as post-traumatic strictures, bilateral vocal cord paralysis and chronic inflammatory foci are uncommon. The functional assessment of the severity and character of an obstruction is important both for diagnosis and management, and may also allow evaluation of the efficacy of medical and surgical treatment. There are limitations of simple spirometric pulmonary function tests, which are evident when assessing upper airways obstruction. The flow volume loop is a graphic recording of airflow during maximal respiration and expiration at different lung volumes, and may be affected in a characteristic way by alterations in the airway resistance. Three unusual cases of chronic upper airway obstruction are presented which illustrate the value of the flow volume loop examination in their management.
An advective volume-balance model for flow in porous media
Malaga, Carlos; Mandujano, Francisco; Becerra, Julian
2016-11-01
Volume-balance models are used by petroleum engineers to simulate multiphase and multicomponent flow phenomena in porous media and the extraction process in oil reservoirs. In these models, mass conservation equations and Darcy's law are supplemented by a balance condition for the pore and fluid volumes. This provides a pressure equation suitable for simulating a compressible flow within a compressible solid matrix. Here we present an alternative interpretation of the volume-balance condition that includes the advective transport within a consolidated porous media. We obtain a modified equation for the time evolution of the pressure field. Preliminary numerical tests of phase separation due to gravity suggest the model reproduces qualitatively the physical phenomena. Fondo Sectorial CONACYT-SENER Grant Number 42536 (DGAJ-SPI-34-170412-217).
Multiphase flow through porous media: an adaptive control volume finite element formulation
Mostaghimi, P.; Tollit, B.; Gorman, G.; Neethling, S.; Pain, C.
2012-12-01
Accurate modeling of multiphase flow in porous media is of great importance in a wide range of applications in science and engineering. We have developed a numerical scheme which employs an implicit pressure explicit saturation (IMPES) algorithm for the temporal discretization of the governing equations. The saturation equation is spatially discretized using a node centered control volume method on an unstructured finite element mesh. The face values are determined through an upwind scheme. The pressure equation is spatially discretized using a continuous control volume finite element method (CV-FEM) to achieve consistency with the discrete saturation equation. The numerical simulation is implemented in Fluidity, an open source and general purpose fluid simulator capable of solving a number of different governing equations for fluid flow and accompanying field equations on arbitrary unstructured meshes. The model is verified against the Buckley-Leverett problem where a quasi-analytical solution is available. We discuss the accuracy and the order of convergence of the scheme. We demonstrate the scheme for modeling multiphase flow in a synthetic heterogeneous porous medium along with the use of anisotropic mesh adaptivity to control local solution errors and increase computational efficiency. The adaptive method is also used to simulate two-phase flow in heap leaching, an industrial mining process, where the flow of the leaching solution is gravitationally dominated. Finally we describe the extension of the developed numerical scheme for simulation of flow in multiscale fractured porous media and its capability to model the multiscale characterization of flow in full scale.
Yo Takemoto; Erika Ota; Daisuke Yoneoka; Rintaro Mori; Satoru Takeda
2016-01-01
Since low birthweight has been correlated with both neonatal and long-term health, we performed this epidemiological study to evaluate the Japanese secular trends in mean birthweight and the prevalence of preterm/term low birthweight infants during the last three decades. We used population-based birth certificate data from January 1979 to December 2010. Time trends were analysed using a linear regression model. During the study period, we observed a significant decrease in the mean birthweig...
A Mixed Finite Volume Element Method for Flow Calculations in Porous Media
Jones, Jim E.
1996-01-01
A key ingredient in the simulation of flow in porous media is the accurate determination of the velocities that drive the flow. The large scale irregularities of the geology, such as faults, fractures, and layers suggest the use of irregular grids in the simulation. Work has been done in applying the finite volume element (FVE) methodology as developed by McCormick in conjunction with mixed methods which were developed by Raviart and Thomas. The resulting mixed finite volume element discretization scheme has the potential to generate more accurate solutions than standard approaches. The focus of this paper is on a multilevel algorithm for solving the discrete mixed FVE equations. The algorithm uses a standard cell centered finite difference scheme as the 'coarse' level and the more accurate mixed FVE scheme as the 'fine' level. The algorithm appears to have potential as a fast solver for large size simulations of flow in porous media.
Vital capacities in acute and chronic airway obstruction: dependence on flow and volume histories.
Brusasco, V; Pellegrino, R; Rodarte, J R
1997-06-01
The aim of this study was to investigate whether measurements of vital capacity (VC) are affected by the direction of the manoeuvre (inspiratory vs expiratory) and by the rate of expiratory flow. The study was performed on 25 individuals with chronic airway obstruction (CAO) and a forced expiratory volume in one second (FEV1) (expressed in standardized residuals (SR)) of -2.0+/-1.4 SD (CAO group), and 10 asthmatic subjects with methacholine (MCh)-induced bronchoconstriction (FEV1 -23+/-1.02 SR) (MCh group). VCs were measured during fast inspiration following both slow (FIVCse) and forced (FIVCfe) expiration from end-tidal inspiration to residual volume (RV), and during slow (EVC) or forced (FVC) expiration from total lung capacity (TLC). In the CAO group, FVC was the smallest volume (3.75+/-1.03 L) and significantly different from the other three estimates of VC; FIVCse (4.03+/-0.91 L) was the largest volume and significantly different from FVC and FIVCfe (3.83+/-0.98 L). In the MCh group, FVC (4.16+/-0.94 L) and EVC (4.19+/-0.89 L) were the largest volumes, although only the difference between FVC and FIVCfe (3.76+/-0.81 L) reached statistical significance. These data suggest that both flow and volume histories contribute to decreased vital capacities during bronchoconstriction. However, whereas increasing expiratory flow always tends to decrease vital capacity, the volume history of full inflation has different effects in chronic and acute bronchoconstriction, probably due to different effects on airway calibre. These results stress the importance of using standardized manoeuvres in order to obtain comparable values of vital capacity.
Low birthweight and prematurity in relation to paternal factors
DEFF Research Database (Denmark)
Basso, Olga; Olsen, Jørn; Christensen, Kaare
1999-01-01
was associated with changes in the recurrence risk. Fathers who changed partner had offspring with similar birthweight and gestational length between the three sub-cohorts, while a difference was evident in offspring to fathers whose female partner was unchanged. CONCLUSIONS: We did not identify any paternal...
Brazelton Scale Performance of Infants of Varying Birthweight.
Emory, E. Kenneth; And Others
The effects of low, full (normal) and high birthweights on the broad range of neonatal behaviors measured by the Brazelton Neonatal Assessment Scale were investigated in a study which also attempted to replicate results of the authors' earlier study of the Brazelton Scale. Data from the original sample of 52 infants were included in the later…
Cannon, S.H.; Gartner, J.E.; Rupert, M.G.; Michael, J.A.; Rea, A.H.; Parrett, C.
2010-01-01
Empirical models to estimate the probability of occurrence and volume of postwildfire debris flows can be quickly implemented in a geographic information system (GIS) to generate debris-flow hazard maps either before or immediately following wildfires. Models that can be used to calculate the probability of debris-flow production from individual drainage basins in response to a given storm were developed using logistic regression analyses of a database from 388 basins located in 15 burned areas located throughout the U.S. Intermountain West. The models describe debris-flow probability as a function of readily obtained measures of areal burned extent, soil properties, basin morphology, and rainfall from short-duration and low-recurrence-interval convective rainstorms. A model for estimating the volume of material that may issue from a basin mouth in response to a given storm was developed using multiple linear regression analysis of a database from 56 basins burned by eight fires. This model describes debris-flow volume as a function of the basin gradient, aerial burned extent, and storm rainfall. Applications of a probability model and the volume model for hazard assessments are illustrated using information from the 2003 Hot Creek fire in central Idaho. The predictive strength of the approach in this setting is evaluated using information on the response of this fire to a localized thunderstorm in August 2003. The mapping approach presented here identifies those basins that are most prone to the largest debris-flow events and thus provides information necessary to prioritize areas for postfire erosion mitigation, warnings, and prefire management efforts throughout the Intermountain West.
Yinwei Lin; Chen, C. K.
2015-01-01
In order to solve the velocity profile and pressure gradient of the unsteady unidirectional slip flow of Voigt fluid, Laplace transform method is adopted in this research. Between the parallel microgap plates, the flow motion is induced by a prescribed arbitrary inlet volume flow rate which varies with time. The velocity slip condition on the wall and the flow conditions are known. In this paper, two basic flow situations are solved, which are a suddenly started and a constant acc...
Muscular adaptations after two different volumes of blood flow-restricted training.
Martín-Hernández, J; Marín, P J; Menéndez, H; Ferrero, C; Loenneke, J P; Herrero, A J
2013-03-01
This study aimed to gain an insight into the adaptations of muscle strength and skeletal muscle thickness after two different volumes of blood flow restriction training (BFRT), and compare them with high-intensity training. The sample was divided into four groups: low-volume, low-intensity BFRT (BFRT LV); high-volume, low-intensity BFRT (BFRT HV); traditional high-intensity resistance training (HIT); and a control group, which maintained their routine activities (CON). Leg extension one repetition maximum (1RM), isokinetic peak knee extension, and flexion torques at 60°/s and 180°/s as well as muscle thickness of the rectus femoris (RF) and vastus lateralis (VL) were assessed at baseline and after 5 weeks of training BFRT LV (7.03%, P muscular size or strength. Although similar increases in muscle thickness were observed between training groups, HIT increased 1RM performance to a greater extent compared to either volume of BFRT.
Schneider, T.; Botta, N.; Geratz, K. J.; Klein, R.
1999-11-01
When attempting to compute unsteady, variable density flows at very small or zero Mach number using a standard finite volume compressible flow solver one faces at least the following difficulties: (i) Spatial pressure variations vanish as the Mach number M→0, but they do affect the velocity field at leading order; (ii) the resulting spatial homogeneity of the leading order pressure implies an elliptic divergence constraint for the energy flux; (iii) violations of this constraint crucially affect the transport of mass, preventing a code to properly advect even a constant density distribution. We overcome these difficulties through a new algorithm for constructing numerical fluxes in the context of multi-dimensional finite volume methods in conservation form. The construction of numerical fluxes involves: (1) An explicit upwind step yielding predictions for the nonlinear convective flux components. (2) A first correction step that introduces pressure gradients which guarantee compliance of the convective fluxes with a divergence constraint. This step requires the solution of a first Poisson-type equation. (3) A second projection step which provides the yet unknown (non-convective) pressure contribution to the total flux of momentum. This second projection requires the solution of another Poisson-type equation and yields the cell centered velocity field at the new time. This velocity field exactly satisfies a divergence constraint consistent with the asymptotic limit. Step (1) can be done by any standard finite volume compressible flow solver. The input to steps (2) and (3) involves solely the fluxes from step (1) and is independent of how these were obtained. Thus, our approach allows any such solver to be extended to compute variable density incompressible flows.
DEFF Research Database (Denmark)
Andersen, Vibeke; Sonne, J; Court-Payen, M
1999-01-01
The aim of the study was to examine liver volume, portal vein flow, and indocyanine green (ICG) and antipyrine clearance in hyperthyroidism before and after antithyroid drug treatment.......The aim of the study was to examine liver volume, portal vein flow, and indocyanine green (ICG) and antipyrine clearance in hyperthyroidism before and after antithyroid drug treatment....
DEFF Research Database (Denmark)
Andersen, Vibeke; Sonne, J; Court-Payen, M
1999-01-01
The aim of the study was to examine liver volume, portal vein flow, and indocyanine green (ICG) and antipyrine clearance in hyperthyroidism before and after antithyroid drug treatment.......The aim of the study was to examine liver volume, portal vein flow, and indocyanine green (ICG) and antipyrine clearance in hyperthyroidism before and after antithyroid drug treatment....
Pasquier, Jennifer; Rioult, Damien; Abu-Kaoud, Nadine; Hoarau-Véchot, Jessica; Marin, Matthieu; Le Foll, Frank
2015-06-24
The regulation of cell volume is an essential function that is coupled to a variety of physiological processes such as receptor recycling, excitability and contraction, cell proliferation, migration, and programmed cell death. Under stress, cells undergo emergency swelling and respond to such a phenomenon with a regulatory volume decrease (RVD) where they release cellular ions, and other osmolytes as well as a concomitant loss of water. The link between P-glycoprotein, a transmembrane transporter, and cell volume regulation is controversial, and changes in cells volume are measured using microscopy or electrophysiology. For instance, by using the patch-clamp method, our team demonstrated that chloride currents activated in the RVD were more intense and rapid in a breast cancer cell line overexpressing the P-glycoprotein (P-gp). The Cell Lab Quanta SC is a flow cytometry system that simultaneously measures electronic volume, side scatter and three fluorescent colors; altogether this provides unsurpassed population resolution and accurate cell counting. Therefore, here we propose a novel method to follow cellular volume. By using the Coulter-type channel of the cytometer Cell Lab Quanta SC MPL (multi-platform loading), we demonstrated a role for the P-gp during different osmotic treatments, but also a differential activity of the P-gp through the cell cycle. Altogether, our data strongly suggests a role of P-gp in cell volume regulation.
Directory of Open Access Journals (Sweden)
Jennifer Pasquier
2015-06-01
Full Text Available The regulation of cell volume is an essential function that is coupled to a variety of physiological processes such as receptor recycling, excitability and contraction, cell proliferation, migration, and programmed cell death. Under stress, cells undergo emergency swelling and respond to such a phenomenon with a regulatory volume decrease (RVD where they release cellular ions, and other osmolytes as well as a concomitant loss of water. The link between P-glycoprotein, a transmembrane transporter, and cell volume regulation is controversial, and changes in cells volume are measured using microscopy or electrophysiology. For instance, by using the patch-clamp method, our team demonstrated that chloride currents activated in the RVD were more intense and rapid in a breast cancer cell line overexpressing the P-glycoprotein (P-gp. The Cell Lab Quanta SC is a flow cytometry system that simultaneously measures electronic volume, side scatter and three fluorescent colors; altogether this provides unsurpassed population resolution and accurate cell counting. Therefore, here we propose a novel method to follow cellular volume. By using the Coulter-type channel of the cytometer Cell Lab Quanta SC MPL (multi-platform loading, we demonstrated a role for the P-gp during different osmotic treatments, but also a differential activity of the P-gp through the cell cycle. Altogether, our data strongly suggests a role of P-gp in cell volume regulation.
Expiratory flow limitation and operating lung volumes during exercise in older and younger adults.
Smith, Joshua R; Kurti, Stephanie P; Meskimen, Kayla; Harms, Craig A
2017-02-20
We determined the effect of aging on expiratory flow limitation (EFL) and operating lung volumes when matched for lung size. We hypothesized that older adults will exhibit greater EFL and increases in EELV during exercise compared to younger controls. Ten older (5M/5W; >60years old) and nineteen height-matched young adults (10M/9W) were recruited. Young adults were matched for%predicted forced vital capacity (FVC) (Y-matched%Pred FVC; n=10) and absolute FVC (Y-matched FVC; n=10). Tidal flow-volume loops were recorded during the incremental exercise test with maximal flow-volume loops measured pre- and post-exercise. Compared to younger controls, older adults exhibited more EFL at ventilations of 26, 35, 51, and 80L/min. The older group had higher end-inspiratory lung volume compared to Y-matched%Pred FVC group during submaximal ventilations. The older group increased EELV during exercise, while EELV stayed below resting in the Y-matched%Pred FVC group. These data suggest older adults exhibit more EFL and increase EELV earlier during exercise compared to younger adults.
Energy Technology Data Exchange (ETDEWEB)
Leao, Alberto Ribeiro de Souza; Santos, Jose Eduardo Mourao; Moulin, Danilo Sales; Shigueoka, David Carlos; D' Ippolito, Giuseppe [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Escola Paulista de Medicina. Dept. de Diagnostico por Imagem]. E-mail: ar.leao@uol.com.br; Colleoni, Ramiro [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Escola Paulista de Medicina. Dept. de Gastroenterologia
2008-09-15
Objective: To evaluate the reproducibility of Doppler ultrasonography in the measurement of portal blood flow volume in schistosomal patients. Materials and methods: Prospective, transversal, observational and self-paired study evaluating 21 patients with hepatosplenic schistosomiasis submitted to Doppler ultrasonography performed by three independent observers for measurement of portal blood flow. Pairwise interobserver agreement was calculated by means of the intraclass correlation coefficient, paired t-test and Pearson's correlation coefficient. Results: Interobserver agreement was excellent. Intraclass correlation ranged from 80.6% to 93.0% (IC at 95% [65.3% ; 95.8%]), with the Pearson's correlation coefficient ranging between 81.6% and 92.7% with no statistically significant interobserver difference regarding the mean portal blood flow volume measured by Doppler ultrasonography (p = 0.954 / 0.758 / 0.749). Conclusion: Doppler ultrasonography has demonstrated to be a reliable method for measuring the portal blood flow volume in patients with portal hypertension secondary to schistosomiasis, with a good interobserver agreement. (author)
Volume fraction prediction in biphasic flow using nuclear technique and artificial neural network
Energy Technology Data Exchange (ETDEWEB)
Salgado, Cesar M.; Brandao, Luis E.B., E-mail: otero@ien.gov.br, E-mail: brandao@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2015-07-01
The volume fraction is one of the most important parameters used to characterize air-liquid two-phase flows. It is a physical value to determine other parameters, such as the phase's densities and to determine the flow rate of each phase. These parameters are important to predict the flow pattern and to determine a mathematical model for the system. To study, for example, heat transfer and pressure drop. This work presents a methodology for volume fractions prediction in water-gas stratified flow regime using the nuclear technique and artificial intelligence. The volume fractions calculate in biphasic flow systems is complex and the analysis by means of analytical equations becomes very difficult. The approach is based on gamma-ray pulse height distributions pattern recognition by means of the artificial neural network. The detection system uses appropriate broad beam geometry, comprised of a ({sup 137}Cs) energy gamma-ray source and a NaI(Tl) scintillation detector in order measure transmitted beam whose the counts rates are influenced by the phases composition. These distributions are directly used by the network without any parameterization of the measured signal. The ideal and static theoretical models for stratified regime have been developed using MCNP-X code, which was used to provide training, test and validation data for the network. The detector also was modeled with this code and the results were compared to experimental photopeak efficiency measurements of radiation sources. The proposed network could obtain with satisfactory prediction of the volume fraction in water-gas system, demonstrating to be a promising approach for this purpose. (author)
Finite volume numerical solution to a blood flow problem in human artery
Wijayanti Budiawan, Inge; Mungkasi, Sudi
2017-01-01
In this paper, we solve a one dimensional blood flow model in human artery. This model is of a non-linear hyperbolic partial differential equation system which can generate either continuous or discontinuous solution. We use the Lax–Friedrichs finite volume method to solve this model. Particularly, we investigate how a pulse propagates in human artery. For this simulation, we give a single sine wave with a small time period as an impluse input on the left boundary. The finite volume method is successful in simulating how the pulse propagates in the artery. It detects the positions of the pulse for the whole time period.
Assessment of the adequacy of bronchial stenting by flow-volume loops
Energy Technology Data Exchange (ETDEWEB)
McLaren, Clare A.; Roebuck, Derek J. [Great Ormond Street Hospital for Children, Department of Radiology, London (United Kingdom); Pigott, Nick; Elliott, Martin J. [Great Ormond Street Hospital for Children, Cardiothoracic Unit, London (United Kingdom); Dunne, Catherine [Great Ormond Street Hospital for Children, Department of Physiotherapy, London (United Kingdom)
2006-08-15
Airway compression is a common problem in children with certain forms of congenital heart disease. Although various surgical approaches are available to overcome this form of airway obstruction, internal stenting is necessary in a minority of patients. It can be difficult to assess the success of stenting at the time of the procedure, and the interval to successful extubation is usually used as an outcome measure. Measurement of relevant parameters of respiratory physiology with flow-volume and volume-pressure loops permits immediate quantitative assessment of the adequacy of stenting. A 3-month-old infant who underwent bronchial stenting and physiological assessment at the time of the procedure is described. (orig.)
The Effect of the Volume Flow rate on the Efficiency of a Solar Collector
DEFF Research Database (Denmark)
Fan, Jianhua; Shah, Louise Jivan; Furbo, Simon
rates. Theoretically, a simplified model of the solar collector panel is built by means of the CFD (Computational Fluid Dynamics) code Fluent, where the geometry of the collector panel except the casing is fully modeled. Both lateral and longitudinal heat conduction in the absorber fins, the heat...... transfer from the absorber to the solar collector fluid and the heat loss from the absorber are considered. Flow and temperature distribution in the collector panel are investigated with buoyancy effect. Measurements are carried out with the solar collector panel. Collector efficiencies are measured......The flow distribution inside a collector panel with an area of 12.5 m² and with 16 parallel connected horizontal fins and the effect of the flow nonuniformity on the risk of boiling and on the collector efficiency have been theoretically and experimentally investigated for different volume flow...
Validation of a continuous penile blood-flow measurement by pulse-volume-plethysmography.
Lavoisier, P; Barbe, R; Gally, M
2002-04-01
Today, in the assessment of cavernous artery blood-flow, the most commonly used technique is Doppler ultrasound velocimetry (continuous, pulsed, color-coded or power), which is often considered as the gold standard. Plethysmographic techniques and radioactive tracers have been widely used for the assessment of global penis flow variations but are not adequate for continuous blood-flow measurement. A new pulse-volume plethysmographic (PVP) device using a water-filled penile cuff was employed to assess continuous blood-flow measurement in the penis. Simultaneously Doppler velocity was recorded and served as a gold standard. A penile water-cuff is connected through a pressure tube to a three-way tap. The pulse-volume changes in the penile water-cuff are measured by means of a latex membrane placed over one of the three-way taps. The displacements of the latex are recorded by a photoplethysmograph. The third tap is connected to a 5 l perfusion bag placed 30 cm above the penis so as to maintain constant pressure in the whole device whatever the penis volume. Twenty-four volunteers were tested. The Doppler velocity signal and pulse volume of cavernous arteries were measured simultaneously after PGE1 intra-cavernous injection. Blood-flow variations were induced by increasing penis artery compression with a second penile water-cuff used as a tourniquet fitted onto the penis root, and the pressure of which could be modified by a water-filled syringe. The amplitude of the plethysmographic pulse-volume signal and the area under the Doppler velocity signal were correlated. The inter-patient (n=24) correlation ranged from 0.455 to 0.904, with a mean correlation of 0.704 and P<0.0001. PVP measurement by a water-filled cuff was validated by ultrasound velocimetry. This new continuous, non-invasive and easy-to-use technique enables physiological and physiopathological flow-measurement during sleep, under visual sexual stimulation (VSS), or following artificial erection
Energy Technology Data Exchange (ETDEWEB)
Inoue, Toshihisa; Watanabe, Shigeru; Sakurada, Hideki; Ono, Katsuhiro; Urano, Miharu; Hijikata, Yasuyoshi; Saito, Isao; Masuda, Yoshiaki [Chiba Univ. (Japan). School of Medicine
2000-10-01
In 21 patients with chronic aortic dissections and proven patent false lumens, the flow volume and flow patterns in the patent false lumens was evaluated using velocity-encoded cine magnetic resonance imaging (VENC-MRI) and the relationship between the flow characteristics and aortic enlargement was retrospectively examined. Flow patterns in the false lumen were divided into 3 groups: pattern A with primarily antegrade flow (n=6), pattern R with primarily retrograde flow (n=3), and pattern B with bidirectional flow (n=12). In group A, the rate of flow volume in the false lumen compared to the total flow volume in true and false lumens (%TFV) and the average rate of enlargement of the maximum diameter of the dissected aorta per year ({delta}D) were significantly greater than in groups R and B (%TFV: 74.1{+-}0.07 vs 15.2{+-}0.03 vs 11.8{+-}0.04, p<0.01; {delta}D: 3.62{+-}0.82 vs 0 vs 0.58{+-}0.15 mm/year, p<0.05, respectively). There was a significant correlation between %TFV and {delta}D (r=0.79, p<0.0001). Evaluation of flow volume and flow patterns in the patent false lumen using VENC-MRI may be useful for predicting enlargement of the dissected aorta. (author)
FINITE VOLUME METHOD FOR SIMULATION OF VISCOELASTIC FLOW THROUGH A EXPANSION CHANNEL
Institute of Scientific and Technical Information of China (English)
FU Chun-quan; JIANG Hai-mei; YIN Hong-jun; SU Yu-chi; ZENG Ye-ming
2009-01-01
A finite volume method for the numerical solution of viscoelastic flows is given. The flow of a differential Upper-Convected Maxwell (UCM) fluid through an abrupt expansion has been chosen as a prototype example. The conservation and constitutive equations are solved using the Finite Volume Method (FVM) in a staggered grid with an upwind scheme for the viscoelastic stresses and a hybrid scheme for the velocities. An enhanced-in-speed pressure-correction algorithm is used and a method for handling the source term in the momentum equations is employed. Improved accuracy is achieved by a special discretization of the boundary conditions. Stable solutions are obtained for higher Weissenberg number (We), further extending the range of simulations with the FVM. Numerical results show the viscoelasticity of polymer solutions is the main factor influencing the sweep efficiency.
Van Der Schijff, Hermanus P.
Variable air volume (VAV) air terminals are designed to save energy by reducing airflow into a given space based on occupancy and required load. Systems are typically designed to operate at peak load, however as load is reduced, performance is compromised due to inadequate throw. As a result, fans are installed to adjust for the losses, negating many of the energy savings. Additionally flow is vectored by the use of vanes, a basic passive type of flow control. An experimental investigation was performed to study the application of flow control on that of a HVAC diffuser using synthetic jets distributed evenly along the diffuser edge parallel to the flow field. The study was conducted on a 1:3 scale typical office space (150 ft2), which included a simulated scale HVAC system supplied by compressed air. Two different jet blowing ratios were investigated for system loads of 60% and 90%. The flow field was established using hot wire anemometry and Particle Image Velocimetry (PIV). This study demonstrates the effectiveness of synthetic jet based active flow control at controlling airflow, showing ability to affect throw parameters for changing flow rates within the test chamber. Vectoring of up to 20% and improvement in jet spread of 200% was demonstrated. The use of such devices has the potential to improve air quality and air distribution in building while simultaneously lowering energy demands of HVAC systems.
Madkour, Aubrey Spriggs; Harville, Emily Wheeler; Xie, Yiqiong
2014-04-01
To study the relationship between neighborhood demographic characteristics (disadvantage, racial concentration) and the birthweight of infants born to adolescent mothers, potentially as mediated by smoking, prenatal care use, or perceptions of neighborhood safety. Data from Waves I and IV of the National Longitudinal Survey of Adolescent Health were analyzed. Birthweight (continuous) and low birthweight (<2.5 kg) of singleton infants born to non-Hispanic Black and non-Hispanic White adolescent mothers (<20 years) after Wave I were examined as outcomes. Neighborhood demographic characteristics included Census Block Group socioeconomic disadvantage and Black racial concentration. Possible mediators (smoking during pregnancy, early initiation of prenatal care, and perceptions of safety) were also examined. Controls for adolescent baseline age, age at pregnancy, body mass index (BMI) and parental education were included. Analyses were run stratified on race. Baseline continuous birthweight, BMI and neighborhood demographics varied significantly between non-Hispanic Black and White adolescent mothers, with Black adolescent mothers evidencing lower birthweight and higher BMI, neighborhood disadvantage and Black racial concentration. In multivariable analyses among Black adolescent mothers, Black racial concentration was positively associated with birthweight, and negatively associated with low birthweight; no mediators were supported. Neighborhood disadvantage and Black racial concentration were unassociated with birthweight outcomes among White adolescent mothers. Infants born to Black adolescent mothers evidenced higher birthweight with increasing Black neighborhood concentration. Further exploration of mechanisms by which Black racial concentration may positively impact birthweight is warranted.
The effects of birthweight and breastfeeding on asthma among children aged 1-5 years.
Xu, Xiaohui; Dailey, Amy B; Freeman, Natalie C; Curbow, Barbara A; Talbott, Evelyn O
2009-11-01
Asthma is a major cause of morbidity and mortality among children and has steadily increased in prevalence. The combined effect of birthweight and breastfeeding on childhood asthma remains unclear. In this study, we analysed a nationally representative sample of children aged 1-5 years from the National Health and Nutrition Examination Survey 1999-2002. Logistic regression was performed to examine the hypothesis whether birthweight and breastfeeding are independently associated with the prevalence of asthma after accounting for the complex sampling design. In addition, we sought to describe the relationship between birthweight and childhood asthma and to assess the potentially combined effect between birthweight and breastfeeding on asthma among children aged 1-5 years after considering the possible effects of social and environmental factors. We found that birthweight (measured continuously) was inversely and linearly associated with the prevalence of childhood asthma (odds ratio (OR) = 0.80 per 1 kg increase in birthweight, 95% confidence interval (CI): 0.65-0.98). Using a categorical variable, low birthweight (LBW) was positively associated with childhood asthma (OR = 1.28, 95% CI: 0.81-2.68). Furthermore, we detected an interaction between birthweight and breastfeeding on childhood asthma. Breastfeeding had a strong protective effect on asthma among children with high birthweight (OR = 0.14, 95% CI: 0.04-0.43) while it had no significant effect on asthma among children with normal birthweight or LBW. The mechanisms underlying these relationships remain uncertain and warrant further explanation.
Determination of micro-litre volumes with high accuracy for flow cytometric blood cell counting
Reitz, S.; Kummrow, A.; Kammel, M.; Neukammer, J.
2010-07-01
We have gravimetrically calibrated the volumes dispensed by 1 mL syringes in the range between 1 µL and 100 µL using ultra-pure water. Protocols are based on series of consecutive difference measurements of masses in order to precisely compensate for evaporation, being the most important disturbing quantity. We determined expanded uncertainties of volume measurements for glass syringes of typically 0.2% (expansion factor 2) when dispensing volumes of 10 µL. For polypropylene syringes, selected with respect to the manufacturer, expanded uncertainties of 0.25% (expansion factor 2) were observed. Calibrated syringes were applied for measuring concentrations of blood cells in a flow cytometer demonstrating the capability to determine reference measurement values. Since the direct interaction of blood cells and syringe walls may lead to cell adhesion, glass syringes as well as (disposable) polypropylene syringes were calibrated.
Cornelius, Nathan R.; Nishimura, Nozomi; Suh, Minah; Schwartz, Theodore H.; Doerschuk, Peter C.
2015-08-01
Objective. To describe a toolkit of components for mathematical models of the relationship between cortical neural activity and space-resolved and time-resolved flows and volumes of oxygenated and deoxygenated hemoglobin motivated by optical intrinsic signal imaging (OISI). Approach. Both blood flow and blood volume and both oxygenated and deoxygenated hemoglobin and their interconversion are accounted for. Flow and volume are described by including analogies to both resistive and capacitive electrical circuit elements. Oxygenated and deoxygenated hemoglobin and their interconversion are described by generalization of Kirchhoff's laws based on well-mixed compartments. Main results. Mathematical models built from this toolkit are able to reproduce experimental single-stimulus OISI results that are described in papers from other research groups and are able to describe the response to multiple-stimuli experiments as a sublinear superposition of responses to the individual stimuli. Significance. The same assembly of tools from the toolkit but with different parameter values is able to describe effects that are considered distinctive, such as the presence or absence of an initial decrease in oxygenated hemoglobin concentration, indicating that the differences might be due to unique parameter values in a subject rather than different fundamental mechanisms.
Energy Technology Data Exchange (ETDEWEB)
Salgado, C.M.; Pereira, Claudio M.N.A.; Brandao, Luis E.B., E-mail: otero@ien.gov.b, E-mail: cmnap@ien.gov.b, E-mail: brandao@ien.gov.b [Instituto de Engenharia Nuclear (DIRA/IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Radiofarmacos
2011-07-01
This work investigates the response of a volume fraction prediction system for water-gas-oil multiphase flows considering variations on water salinity. The approach is based on gamma-ray pulse height distributions pattern recognition by means the artificial neural networks (ANNs). The detection system uses appropriate fan beam geometry, comprised of a dual-energy gamma-ray source and two NaI(Tl) detectors adequately positioned outside the pipe in order measure transmitted and scattered beams. An ideal and static theoretical model for annular flow regime have been developed using MCNP-X code, which was used to provide training, test and validation data for the ANN. More than 500 simulations have been done, in which water salinity have been ranged from 0 to 16% in order to cover a most practical situations. Validation tests have included values of volume fractions and water salinity different from those used in ANN training phase. The results presented here show that the proposed approach may be successfully applied to material volume fraction prediction on watergas- oil multiphase flows considering practical (real) levels of variations in water salinity. (author)
Martin, R. M.; Nicolas, A. N.
2003-04-01
A modeling approach of gas solid flow, taking into account different physical phenomena such as gas turbulence and inter-particle interactions is presented. Moment transport equations are derived for the second order fluctuating velocity tensor which allow to involve practical closures based on single phase turbulence modeling on one hand and kinetic theory of granular media on the other hand. The model is applied to fluid catalytic cracking processes and explosive volcanism. In the industry as well as in the geophysical community, multiphase flows are modeled using a finite volume approach and a multicorrector algorithm in time in order to determine implicitly the pressures, velocities and volume fractions for each phase. Pressures, and velocities are generally determined at mid-half mesh step from each other following the staggered grid approach. This ensures stability and prevents oscillations in pressure. It allows to treat almost all the Reynolds number ranges for all speeds and viscosities. The disadvantages appear when we want to treat more complex geometries or if a generalized curvilinear formulation of the conservation equations is considered. Too many interpolations have to be done and accuracy is then lost. In order to overcome these problems, we use here a similar algorithm in time and a Rhie and Chow interpolation (1983) of the collocated variables and essentially the velocities at the interface. The Rhie and Chow interpolation of the velocities at the finite volume interfaces allows to have no oscillations of the pressure without checkerboard effects and to stabilize all the algorithm. In a first predictor step, fluxes at the interfaces of the finite volumes are then computed using 2nd and 3rd order shock capturing schemes of MUSCL/TVD or Van Leer type, and the orthogonal stress components are treated implicitly while cross viscous/diffusion terms are treated explicitly. Pentadiagonal linear systems are solved in each geometrical direction (the so
Cross-Diffusion Systems with Excluded-Volume Effects and Asymptotic Gradient Flow Structures
Bruna, Maria; Burger, Martin; Ranetbauer, Helene; Wolfram, Marie-Therese
2017-04-01
In this paper, we discuss the analysis of a cross-diffusion PDE system for a mixture of hard spheres, which was derived in Bruna and Chapman (J Chem Phys 137:204116-1-204116-16, 2012a) from a stochastic system of interacting Brownian particles using the method of matched asymptotic expansions. The resulting cross-diffusion system is valid in the limit of small volume fraction of particles. While the system has a gradient flow structure in the symmetric case of all particles having the same size and diffusivity, this is not valid in general. We discuss local stability and global existence for the symmetric case using the gradient flow structure and entropy variable techniques. For the general case, we introduce the concept of an asymptotic gradient flow structure and show how it can be used to study the behavior close to equilibrium. Finally, we illustrate the behavior of the model with various numerical simulations.
An assessment of unstructured grid finite volume schemes for cold gas hypersonic flow calculations
Directory of Open Access Journals (Sweden)
João Luiz F. Azevedo
2009-06-01
Full Text Available A comparison of five different spatial discretization schemes is performed considering a typical high speed flow application. Flowfields are simulated using the 2-D Euler equations, discretized in a cell-centered finite volume procedure on unstructured triangular meshes. The algorithms studied include a central difference-type scheme, and 1st- and 2nd-order van Leer and Liou flux-vector splitting schemes. These methods are implemented in an efficient, edge-based, unstructured grid procedure which allows for adaptive mesh refinement based on flow property gradients. Details of the unstructured grid implementation of the methods are presented together with a discussion of the data structure and of the adaptive refinement strategy. The application of interest is the cold gas flow through a typical hypersonic inlet. Results for different entrance Mach numbers and mesh topologies are discussed in order to assess the comparative performance of the various spatial discretization schemes.
Experimental Validation of Volume of Fluid Method for a Sluice Gate Flow
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A. A. Oner
2012-01-01
Full Text Available Laboratory experiments are conducted for 2D turbulent free surface flow which interacts with a vertical sluice gate. The velocity field, on the centerline of the channel flow upstream of the gate is measured using the particle image velocimetry technique. The numerical simulation of the same flow is carried out by solving the governing equations, Reynolds-averaged continuity and Navier-Stokes equations, using finite element method. In the numerical solution of the governing equations, the standard k-ε turbulence closure model is used to define the turbulent viscosity. The measured horizontal velocity distribution at the inflow boundary of the solution domain is taken as the boundary condition. The volume of fluid (VOF method is used to determine the flow profile in the channel. Taking into account of the flow characteristics, the computational domain is divided into five subdomains, each having different mesh densities. Three different meshes with five subdomains are employed for the numerical model. A grid convergence analysis indicates that the discretization error in the predicted velocities on the fine mesh remains within 2%. The computational results are compared with the experimental data, and, the most suitable mesh in predicting the velocity field and the flow profile among the three meshes is selected.
Finite volume simulation of 2-D steady square lid driven cavity flow at high reynolds numbers
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K. Yapici
2013-12-01
Full Text Available In this work, computer simulation results of steady incompressible flow in a 2-D square lid-driven cavity up to Reynolds number (Re 65000 are presented and compared with those of earlier studies. The governing flow equations are solved by using the finite volume approach. Quadratic upstream interpolation for convective kinematics (QUICK is used for the approximation of the convective terms in the flow equations. In the implementation of QUICK, the deferred correction technique is adopted. A non-uniform staggered grid arrangement of 768x768 is employed to discretize the flow geometry. Algebraic forms of the coupled flow equations are then solved through the iterative SIMPLE (Semi-Implicit Method for Pressure-Linked Equation algorithm. The outlined computational methodology allows one to meet the main objective of this work, which is to address the computational convergence and wiggled flow problems encountered at high Reynolds and Peclet (Pe numbers. Furthermore, after Re > 25000 additional vortexes appear at the bottom left and right corners that have not been observed in earlier studies.
Proteinuria and glomerular hypertrophy in extremely low-birthweight children.
Hayashi, Asako; Santo, Yoko; Satomura, Kenichi
2014-12-01
Of late, there is an increased awareness of the frequent occurrence of hypertension or proteinuria in adults born at low birthweight. We retrospectively studied five children born with extremely low birthweight (ELBW) who were first diagnosed with proteinuria in a school urinary screening program. These children were born at 23-25 weeks of gestation, and their birthweight was 532-732 g. Proteinuria was identified in all the subjects in a school urinary screening program when they were 6-15 years old. Renal biopsy showed diffuse increase in glomerular size, consistent with glomerular hypertrophy. There were no findings of mesangial proliferation or glomerular sclerosis. All the subjects had a marked decrease in proteinuria after angiotensin receptor blocker (ARB) treatment. Reduced number of glomeruli associated with prematurity was speculated to have caused compensatory glomerular hyperfiltration, hypertrophy, and hypertension in children born with ELBW when they developed proteinuria. ARB could have been effective for proteinuria by reducing glomerular hypertension. Physicians should be aware of proteinuria in children born with ELBW because there is an increasing number of ELBW survivors as a result of advances in medical technology. © 2014 Japan Pediatric Society.
The impact of Mexico's conditional cash transfer programme, Oportunidades, on birthweight.
Barber, Sarah L; Gertler, Paul J
2008-11-01
To evaluate the impact of Oportunidades, a large-scale, conditional cash transfer programme in Mexico, on birthweight. The programme provides cash transfers to low-income, rural households in Mexico, conditional on accepting nutritional supplements health education, and health care. The primary analyses used retrospective reports from 840 women in poor rural communities participating in an effectiveness study and randomly assigned to incorporation into the programme in 1998 or 1999 across seven Mexican states. Pregnant women in participating households received nutrition supplements and health care, and accepted cash transfers. Using multivariate and instrumental variable analyses, we estimated the impact of the programme on birthweight in grams and low birthweight (Oportunidades beneficiary status was associated with 127.3 g higher birthweight among participating women and a 4.6 percentage point reduction in low birthweight. The Oportunidades conditional cash transfer programme improved birthweight outcomes. This finding is relevant to countries implementing conditional cash transfer programmes.
Brown-Dymkoski, Eric; Kasimov, Nurlybek; Vasilyev, Oleg V.
2014-04-01
In order to introduce solid obstacles into flows, several different methods are used, including volume penalization methods which prescribe appropriate boundary conditions by applying local forcing to the constitutive equations. One well known method is Brinkman penalization, which models solid obstacles as porous media. While it has been adapted for compressible, incompressible, viscous and inviscid flows, it is limited in the types of boundary conditions that it imposes, as are most volume penalization methods. Typically, approaches are limited to Dirichlet boundary conditions. In this paper, Brinkman penalization is extended for generalized Neumann and Robin boundary conditions by introducing hyperbolic penalization terms with characteristics pointing inward on solid obstacles. This Characteristic-Based Volume Penalization (CBVP) method is a comprehensive approach to conditions on immersed boundaries, providing for homogeneous and inhomogeneous Dirichlet, Neumann, and Robin boundary conditions on hyperbolic and parabolic equations. This CBVP method can be used to impose boundary conditions for both integrated and non-integrated variables in a systematic manner that parallels the prescription of exact boundary conditions. Furthermore, the method does not depend upon a physical model, as with porous media approach for Brinkman penalization, and is therefore flexible for various physical regimes and general evolutionary equations. Here, the method is applied to scalar diffusion and to direct numerical simulation of compressible, viscous flows. With the Navier-Stokes equations, both homogeneous and inhomogeneous Neumann boundary conditions are demonstrated through external flow around an adiabatic and heated cylinder. Theoretical and numerical examination shows that the error from penalized Neumann and Robin boundary conditions can be rigorously controlled through an a priori penalization parameter η. The error on a transient boundary is found to converge as O
Hurlimann Ziegler, Marcel; Abancó, Clàudia; Moya Sánchez, José
2014-01-01
The sophisticated monitoring system installed in the Rebaixader catchment incorporates a total of 6 different stations: four stations recording information on the initiation mechanisms (two meteorological stations and two infiltration stations), and two stations focussing on the debris flow detection and the dynamic behaviour of the flows. Between August 2009 and August 2013, seven debris flows and seventeen debris floods were detected. The volumes of the debris flows ranged from 2,100 to 16,...
Low birthweight as an indicator of child health in Greenland--use, knowledge and implications
Niclasen, Birgit
2007-01-01
OBJECTIVES: The aim of this study was to analyse if low birthweight is a valuable indicator of child health in Greenland. STUDY DESIGN: A case study focusing on "low birthweight as an indicator in Greenland" with 3 units and 5 subunits of analyses. METHODS: Literature reviews, interviews with health care professionals and an analysis of the National Birth Register. RESULTS: Low birthweight was a well-known and yearly surveyed indicator, but not used by clinicians or by policymakers. Resear...
Gartner, J.E.; Cannon, S.H.; Santi, P.M.; deWolfe, V.G.
2008-01-01
Recently burned basins frequently produce debris flows in response to moderate-to-severe rainfall. Post-fire hazard assessments of debris flows are most useful when they predict the volume of material that may flow out of a burned basin. This study develops a set of empirically-based models that predict potential volumes of wildfire-related debris flows in different regions and geologic settings. The models were developed using data from 53 recently burned basins in Colorado, Utah and California. The volumes of debris flows in these basins were determined by either measuring the volume of material eroded from the channels, or by estimating the amount of material removed from debris retention basins. For each basin, independent variables thought to affect the volume of the debris flow were determined. These variables include measures of basin morphology, basin areas burned at different severities, soil material properties, rock type, and rainfall amounts and intensities for storms triggering debris flows. Using these data, multiple regression analyses were used to create separate predictive models for volumes of debris flows generated by burned basins in six separate regions or settings, including the western U.S., southern California, the Rocky Mountain region, and basins underlain by sedimentary, metamorphic and granitic rocks. An evaluation of these models indicated that the best model (the Western U.S. model) explains 83% of the variability in the volumes of the debris flows, and includes variables that describe the basin area with slopes greater than or equal to 30%, the basin area burned at moderate and high severity, and total storm rainfall. This model was independently validated by comparing volumes of debris flows reported in the literature, to volumes estimated using the model. Eighty-seven percent of the reported volumes were within two residual standard errors of the volumes predicted using the model. This model is an improvement over previous models in
Osypuk, Theresa L; Bates, Lisa M; Acevedo-Garcia, Dolores
2010-02-01
Examining whether contextual factors influence the birth outcomes of Mexican-origin infants in the US may contribute to assessing rival explanations for the so-called Mexican health paradox. We examined whether birthweight among infants born to Mexican-origin women in the US was associated with Mexican residential enclaves and exposure to neighborhood poverty, and whether these associations were modified by nativity (i.e. mother's place of birth). We calculated metropolitan indices of neighborhood exposure to Mexican-origin population and poverty for the Mexican-origin population, and merged with individual-level, year 2000 natality data (n=490,332). We distinguished between neighborhood exposure to US-born Mexican-origin population (i.e. ethnic enclaves) and neighborhood exposure to foreign-born (i.e. Mexico-born) Mexican-origin population (i.e. immigrant enclaves). We used 2-level hierarchical linear regression models adjusting for individual, metropolitan, and regional covariates and stratified by nativity. We found that living in metropolitan areas with high residential segregation of US-born Mexican-origin residents (i.e. high prevalence of ethnic enclaves) was associated with lower birthweight for infants of US-born Mexican-origin mothers before and after covariate adjustment. When simultaneously adjusting for exposure to ethnic and immigrant enclaves, the latter became positively associated with birthweight and the negative effect of the former increased, among US-born mothers. We found no contextual birthweight associations for mothers born in Mexico in adjusted models. Our findings highlight a differential effect of context by nativity, and the potential health effects of ethnic enclaves, which are possibly a marker of downward assimilation, among US-born Mexican-origin women. Copyright 2009 Elsevier Ltd. All rights reserved.
Xie, Bin; Xiao, Feng
2016-12-01
We proposed a multi-moment constrained finite volume method which can simulate incompressible flows of high Reynolds number in complex geometries. Following the underlying idea of the volume-average/point-value multi-moment (VPM) method (Xie et al. (2014) [71]), this formulation is developed on arbitrary unstructured hybrid grids by employing the point values (PV) at both cell vertex and barycenter as the prognostic variables. The cell center value is updated via an evolution equation derived from a constraint condition of finite volume form, which ensures the rigorous numerical conservativeness. Novel numerical formulations based on the local PVs over compact stencil are proposed to enhance the accuracy, robustness and efficiency of computations on unstructured meshes of hybrid and arbitrary elements. Numerical experiments demonstrate that the present numerical model has nearly 3-order convergence rate with numerical errors much smaller than the VPM method. The numerical dissipation has been significantly suppressed, which facilitates numerical simulations of high Reynolds number flows in complex geometries.
Patient-specific coronary artery blood flow simulation using myocardial volume partitioning
Kim, Kyung Hwan; Kang, Dongwoo; Kang, Nahyup; Kim, Ji-Yeon; Lee, Hyong-Euk; Kim, James D. K.
2013-03-01
Using computational simulation, we can analyze cardiovascular disease in non-invasive and quantitative manners. More specifically, computational modeling and simulation technology has enabled us to analyze functional aspect such as blood flow, as well as anatomical aspect such as stenosis, from medical images without invasive measurements. Note that the simplest ways to perform blood flow simulation is to apply patient-specific coronary anatomy with other average-valued properties; in this case, however, such conditions cannot fully reflect accurate physiological properties of patients. To resolve this limitation, we present a new patient-specific coronary blood flow simulation method by myocardial volume partitioning considering artery/myocardium structural correspondence. We focus on that blood supply is closely related to the mass of each myocardial segment corresponding to the artery. Therefore, we applied this concept for setting-up simulation conditions in the way to consider many patient-specific features as possible from medical image: First, we segmented coronary arteries and myocardium separately from cardiac CT; then the myocardium is partitioned into multiple regions based on coronary vasculature. The myocardial mass and required blood mass for each artery are estimated by converting myocardial volume fraction. Finally, the required blood mass is used as boundary conditions for each artery outlet, with given average aortic blood flow rate and pressure. To show effectiveness of the proposed method, fractional flow reserve (FFR) by simulation using CT image has been compared with invasive FFR measurement of real patient data, and as a result, 77% of accuracy has been obtained.
National Aeronautics and Space Administration — Thorleaf Research, Inc. proposes to develop a miniaturized high flow, low dead-volume pre-concentrator for monitoring trace levels of contaminants in water under...
Volume preserving mean curvature flow of revolution hypersurfaces between two equidistants
Cabezas-Rivas, Esther
2010-01-01
In a rotationally symmetric space $\\oM$ around an axis A (whose precise definition includes all real space forms), we consider a domain $G$ limited by two equidistant hypersurfaces orthogonal to A. Let $M \\subset \\oM$ be a revolution hypersurface generated by a graph over A, with boundary in $\\partial G$ and orthogonal to it. We study the evolution $M_t$ of $M$ under the volume-preserving mean curvature flow requiring that the boundary of $M_t$ rests on $\\partial G$ and keeps orthogonal to it. We prove that: a) the generating curve of $M_t$ remains a graph; b) the flow exists while $M_t$ does not touch the axis of rotation; c) under a suitable hypothesis relating the enclosed volume and the area of $M$, the flow is defined for every $t\\in [0,\\infty[$ and a sequence of hypersurfaces $M_{t_n}$ converges to a revolution hypersurface of constant mean curvature. Some key points are: i) the results are true even for ambient spaces with positive curvature, ii) the averaged mean curvature does not need to be positive...
Simulation of viscous flows using a multigrid-control volume finite element method
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Hookey, N.A. [Memorial Univ., Newfoundland (Canada)
1994-12-31
This paper discusses a multigrid control volume finite element method (MG CVFEM) for the simulation of viscous fluid flows. The CVFEM is an equal-order primitive variables formulation that avoids spurious solution fields by incorporating an appropriate pressure gradient in the velocity interpolation functions. The resulting set of discretized equations is solved using a coupled equation line solver (CELS) that solves the discretized momentum and continuity equations simultaneously along lines in the calculation domain. The CVFEM has been implemented in the context of both FMV- and V-cycle multigrid algorithms, and preliminary results indicate a five to ten fold reduction in execution times.
An hybrid finite volume finite element method for variable density incompressible flows
Calgaro, Caterina; Creusé, Emmanuel; Goudon, Thierry
2008-04-01
This paper is devoted to the numerical simulation of variable density incompressible flows, modeled by the Navier-Stokes system. We introduce an hybrid scheme which combines a finite volume approach for treating the mass conservation equation and a finite element method to deal with the momentum equation and the divergence free constraint. The breakthrough relies on the definition of a suitable footbridge between the two methods, through the design of compatibility condition. In turn, the method is very flexible and allows to deal with unstructured meshes. Several numerical tests are performed to show the scheme capabilities. In particular, the viscous Rayleigh-Taylor instability evolution is carefully investigated.
Review of the Technical Metrological Regulation for flow computers and volume converters
Almeida, R. O.; Aguiar Júnior, E. A.; Costa-Felix, R. P. B.
2016-07-01
With the publication of Inmetro's regulation n° 373/2014, Inmetro presented the proposal to review the regulation of flow computers and volume converters, whose scope now includes fiscal measurement, ownership, custody transfer, among others, of hydrocarbons liquids and natural gas. This new proposal provides improvements to the legal metrological control of these instruments in Brazil, while also broaden the scope from the previous regulation, the Inmetro's regulation n° 64/2003. The purpose of this paper is to present these changes from a metrological point of view, and also clarify the transitional rules for the process.
Institute of Scientific and Technical Information of China (English)
GAO Wei; DUAN Ya-li; LIU Ru-xun
2009-01-01
In this article a finite volume method is proposed to solve viscous incompressible Navier-Stokes equations in two-dimensional regions with corners and curved boundaries. A hybrid collocated-grid variable arrangement is adopted, in which the velocity and pressure are stored at the centroid and the circumcenters of the triangular control cell, respectively. The cell flux is defined at the mid-point of the cell face. Second-order implicit time integration schemes are used for convection and diffusion terms. The second-order upwind scheme is used for convection fluxes. The present method is validated by results of several viscous flows.
Directory of Open Access Journals (Sweden)
Handa H
1999-02-01
Full Text Available The aim of this study was to determine suitable image parameters and an analytical method for phase-contrast magnetic resonance imaging (PC-MRI as a means of measuring cerebral blood flow volume. This was done by constructing an experimental model and applying the results to a clinical application. The experimental model was constructed from the aorta of a bull and circulating isotonic saline. The image parameters of PC-MRI (repetition time, flip angle, matrix, velocity rate encoding, and the use of square pixels were studied with percent flow volume (the ratio of actual flow volume to measured flow volume. The most suitable image parameters for accurate blood flow measurement were as follows: repetition time, 50 msec; flip angle, 20 degrees; and a 512 x 256 matrix without square pixels. Furthermore, velocity rate encoding should be set ranging from the maximum flow velocity in the vessel to five times this value. The correction in measuring blood flow was done with the intensity of the region of interest established in the background. With these parameters for PC-MRI, percent flow volume was greater than 90%. Using the image parameters for PC-MRI and the analytical method described above, we evaluated cerebral blood flow volume in 12 patients with occlusive disease of the major cervical arteries. The results were compared with conventional xenon computed tomography. The values found with both methods showed good correlation. Thus, we concluded that PC-MRI was a noninvasive method for evaluating cerebral blood flow in patients with occlusive disease of the major cervical arteries.
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Česenek Jan
2016-01-01
Full Text Available In this article we deal with numerical simulation of the non-stationary compressible turbulent flow. Compressible turbulent flow is described by the Reynolds-Averaged Navier-Stokes (RANS equations. This RANS system is equipped with two-equation k-omega turbulence model. These two systems of equations are solved separately. Discretization of the RANS system is carried out by the space-time discontinuous Galerkin method which is based on piecewise polynomial discontinuous approximation of the sought solution in space and in time. Discretization of the two-equation k-omega turbulence model is carried out by the implicit finite volume method, which is based on piecewise constant approximation of the sought solution. We present some numerical experiments to demonstrate the applicability of the method using own-developed code.
Coupling of Smoothed Particle Hydrodynamics with Finite Volume method for free-surface flows
Marrone, S.; Di Mascio, A.; Le Touzé, D.
2016-04-01
A new algorithm for the solution of free surface flows with large front deformation and fragmentation is presented. The algorithm is obtained by coupling a classical Finite Volume (FV) approach, that discretizes the Navier-Stokes equations on a block structured Eulerian grid, with an approach based on the Smoothed Particle Hydrodynamics (SPH) method, implemented in a Lagrangian framework. The coupling procedure is formulated in such a way that each solver is applied in the region where its intrinsic characteristics can be exploited in the most efficient and accurate way: the FV solver is used to resolve the bulk flow and the wall regions, whereas the SPH solver is implemented in the free surface region to capture details of the front evolution. The reported results clearly prove that the combined use of the two solvers is convenient from the point of view of both accuracy and computing time.
Methods to Increase the Robustness of Finite-Volume Flow Models in Thermodynamic Systems
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Sylvain Quoilin
2014-03-01
Full Text Available This paper addresses the issues linked to simulation failures during integration in finite-volume flow models, especially those involving a two-phase state. This kind of model is particularly useful when modeling 1D heat exchangers or piping, e.g., in thermodynamic cycles involving a phase change. Issues, such as chattering or stiff systems, can lead to low simulation speed, instabilities and simulation failures. In the particular case of two-phase flow models, they are usually linked to a discontinuity in the density derivative between the liquid and two-phase zones. In this work, several methods to tackle numerical problems are developed, described, implemented and compared. In addition, methods available in the literature are also implemented and compared to the proposed approaches. Results suggest that the robustness of the models can be significantly increased with these different methods, at the price of a small increase of the error in the mass and energy balances.
MHD flow of dusty nanofluid over a stretching surface with volume fraction of dust particles
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Sandeep Naramgari
2016-06-01
Full Text Available In this study we analyzed the momentum and heat transfer behavior of MHD nanofluid embedded with conducting dust particles past a stretching surface in the presence of volume fraction of dust particles. The governing equations of the flow and heat transfer are transformed into nonlinear ordinary differential equations by using similarity transformation and then solved numerically using Runge–Kutta based shooting technique. The effect of non-dimensional governing parameters on velocity and temperature profiles of the flow are discussed and presented through graphs. Additionally friction factor and the Nusselt number have also been computed. Under some special conditions, numerical results obtained by the present study were compared with the existed studies. The result of the present study proves to be highly satisfactory. The results indicate that an increase in the interaction between the fluid and particle phase enhances the heat transfer rate and reduces the friction factor.
Cerroni, D.; Fancellu, L.; Manservisi, S.; Menghini, F.
2016-06-01
In this work we propose to study the behavior of a solid elastic object that interacts with a multiphase flow. Fluid structure interaction and multiphase problems are of great interest in engineering and science because of many potential applications. The study of this interaction by coupling a fluid structure interaction (FSI) solver with a multiphase problem could open a large range of possibilities in the investigation of realistic problems. We use a FSI solver based on a monolithic approach, while the two-phase interface advection and reconstruction is computed in the framework of a Volume of Fluid method which is one of the more popular algorithms for two-phase flow problems. The coupling between the FSI and VOF algorithm is efficiently handled with the use of MEDMEM libraries implemented in the computational platform Salome. The numerical results of a dam break problem over a deformable solid are reported in order to show the robustness and stability of this numerical approach.
Hu, Yang; Li, Decai; Shu, Shi; Niu, Xiaodong
2016-02-01
Based on the Darcy-Brinkman-Forchheimer equation, a finite-volume computational model with lattice Boltzmann flux scheme is proposed for incompressible porous media flow in this paper. The fluxes across the cell interface are calculated by reconstructing the local solution of the generalized lattice Boltzmann equation for porous media flow. The time-scaled midpoint integration rule is adopted to discretize the governing equation, which makes the time step become limited by the Courant-Friedricks-Lewy condition. The force term which evaluates the effect of the porous medium is added to the discretized governing equation directly. The numerical simulations of the steady Poiseuille flow, the unsteady Womersley flow, the circular Couette flow, and the lid-driven flow are carried out to verify the present computational model. The obtained results show good agreement with the analytical, finite-difference, and/or previously published solutions.
Brito, Aline de Freitas; de Oliveira, Caio Victor Coutinho; Brasileiro-Santos, Maria do Socorro; Santos, Amilton da Cruz
2014-01-01
Background The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects. Methods The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m2) subjected to three experimental sessions, ie, a control session, exercise with a set (S1), and exercise with three sets (S3). For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention) in the supine position. Results Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, −26.5±4.2 mmHg versus −17.9±4.7 mmHg; diastolic blood pressure, −13.8±4.9 mmHg versus −7.7±5 mmHg, P<0.05). Similarly, forearm blood flow and forearm vascular resistance changed significantly in both sessions with an increase and decrease, respectively, that was more evident in S3 than in S1 (P<0.05). Conclusion Resistance exercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular resistance. PMID:25540580
Maximal expiratory and inspiratory flow-volume curves in Parkinson's disease.
Bogaard, J M; Hovestadt, A; Meerwaldt, J; vd Meché, F G; Stigt, J
1989-03-01
In order to investigate the type and degree of upper airway obstruction (UAO) in a group of patients with Parkinson's disease in different stages of the disease, we obtained maximal expiratory and inspiratory flow-volume (MEFV and MIFV) curves and maximal static mouth pressures. The clinical disability was indicated by a Hoehn-Yahr (H-Y) scale, ranging from III to V, and a more continuous Northwestern University Disability Scale (NUDS), ranging from zero to 50. Twelve patients were in H-Y Group III, and eleven and eight were in Groups IV and V, respectively. The pattern of the flow-volume curves was classified as either normal, or with superimposed regular or irregular oscillations (A), or with rounded-off and delayed expiratory peak appearance (B). Mean MEFV curves in Groups III and IV were not appreciably different from reference. In Group V, the mean curve showed a lower peak expiratory flow (PEF) and a more convex tail. Only the effort-dependent variables PEF, peak inspiratory flow (PIF), and maximal mouth pressures at RV and TLC (PmTLC and PmRV) appeared to be significantly correlated with the NUDS index and decreased with increasing clinical disability. The mean values of those variables were also significantly different between the H-Y groups. The number of normal curves decreased from H-Y Group III to Group V. The contribution of A and B curves was relatively equal in the groups, with only a small number of A curves.(ABSTRACT TRUNCATED AT 250 WORDS)
Energy Technology Data Exchange (ETDEWEB)
Hiroshige, Kikura; Gentaro, Yamanaka; Tsuyoshi, Taishi; Masanori, Aritomi [Tokyo Institute of Technology, Tokyo (Japan); Yasushi, Takeda [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Michitsugu, Mori [Tokyo Electric Power Co., Inc. (Japan)
2001-07-01
Ultrasonic Velocity Profile method has many advantages for flow rate measurement of power plant over the conventional flow measurement methods, such as measurement of the instantaneous velocity profile along the measuring line and its applicability to opaque liquids. Furthermore, the method has an advantage of being non-intrusive. Hence, it is applicable to various flow conditions, although it requires a relatively large measurement volume. In this paper, the effects of the measurement volume on the mean velocity profile for flow rate measurements of power plant and the Reynolds stress measurement have been investigated for fully developed turbulent pipe flows in a vertical pipe. The results are then compared with data obtained by Direct Numerical Simulation (DNS). (authors)
Preterm low birthweight and the role of oral bacteria
Directory of Open Access Journals (Sweden)
Elizabeth Shira Davenport
2010-12-01
Full Text Available Preterm and low birthweight (PTLBW continues to be a major cause of mortality and morbidity across the world. In recent years, maternal periodontal disease has been implicated as a risk factor for adverse pregnancy outcomes. There is conflicting evidence to support such an outcome as illustrated by descriptive, case control and randomised controlled trials involving pregnant women from across the world, using different measurement tools to determine the level of periodontal disease. Whilst considering the literature, there is evidence for both arguments, based on the effect of periodontal inflammatory by products. Bacteria associated with periodontal disease are not dissimilar to those known to be associated with genito-urinary bacterial infections and adverse pregnancy outcomes. Several groups have demonstrated the apparent translocation of Fusobacterium nucleatum, Prevotella nigrescens, Prevotella intermedia, Porphyromonus gingivalis, Treponema denticola to the foetal placental unit whereby a maternal or foetal response has been detected resulting in premature birth or low birthweight. The normal process of parturition involves a cascade of events including a build-up of inflammatory mediators as linked to inflammation, whereby the maternal environment becomes hostile and threatens the well-being of the infant, and the foetus expelled. The question remains therefore, is there a greater risk of delivering a PTLBW infant when the mother has detectable periodontal disease, or is the release of inflammatory mediators and their translocation via the haematogenous route sufficient to induce a poor pregnancy outcome? The data investigated would suggest that there is a positive outcome when certain oral gram-negative bacteria create a cumulative effect sufficient to trigger early delivery, which represents the final straw to result in preterm or low birthweight delivery. There is equally sufficient epidemiological evidence that does not support this
Gückel, Friedemann J; Brix, Gunnar; Hennerici, Michael; Lucht, Robert; Ueltzhöffer, Christine; Neff, Wolfgang
2007-10-01
The aim of the present study was a detailed analysis of the regional cerebral blood flow and blood volume in patients with subcortical arteriosclerotic encephalopathy (SAE) by means of functional magnetic resonance imaging (MRI). A group of 26 patients with SAE and a group of 16 age-matched healthy volunteers were examined. Using a well-established dynamic susceptibility contrast-enhanced MRI method, the regional cerebral blood flow (rCBF) and blood volume (rCBV) were quantified for each subject in 12 different regions in the brain parenchyma. As compared to healthy volunteers, patients with SAE showed significantly reduced rCBF and rCBV values in white matter regions and in the occipital cortex. Regions containing predominantly grey matter show almost normal rCBF and rCBV values. In conclusion, quantitative analysis of rCBF and rCBV values demonstrates clearly that SAE is a disease that is associated with a reduced microcirculation predominantly in white matter.
Comparing volume of fluid and level set methods for evaporating liquid-gas flows
Palmore, John; Desjardins, Olivier
2016-11-01
This presentation demonstrates three numerical strategies for simulating liquid-gas flows undergoing evaporation. The practical aim of this work is to choose a framework capable of simulating the combustion of liquid fuels in an internal combustion engine. Each framework is analyzed with respect to its accuracy and computational cost. All simulations are performed using a conservative, finite volume code for simulating reacting, multiphase flows under the low-Mach assumption. The strategies used in this study correspond to different methods for tracking the liquid-gas interface and handling the transport of the discontinuous momentum and vapor mass fractions fields. The first two strategies are based on conservative, geometric volume of fluid schemes using directionally split and un-split advection, respectively. The third strategy is the accurate conservative level set method. For all strategies, special attention is given to ensuring the consistency between the fluxes of mass, momentum, and vapor fractions. The study performs three-dimensional simulations of an isolated droplet of a single component fuel evaporating into air. Evaporation rates and vapor mass fractions are compared to analytical results.
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Berteau C
2015-11-01
Full Text Available Cecile Berteau,1 Orchidée Filipe-Santos,1 Tao Wang,2 Humberto E Rojas,2 Corinne Granger,1 Florence Schwarzenbach1 1Becton-Dickinson Medical Pharmaceutical Systems, Le Pont de Claix, France; 2Eli Lilly and Company, Indianapolis, IN, USA Aim: The primary objective of this study was to evaluate the impact of fluid injection viscosity in combination with different injection volumes and flow rates on subcutaneous (SC injection pain tolerance. Methods: The study was a single-center, comparative, randomized, crossover, Phase I study in 24 healthy adults. Each participant received six injections in the abdomen area of either a 2 or 3 mL placebo solution, with three different fluid viscosities (1, 8–10, and 15–20 cP combined with two different injection flow rates (0.02 and 0.3 mL/s. All injections were performed with 50 mL syringes and 27G, 6 mm needles. Perceived injection pain was assessed using a 100 mm visual analog scale (VAS (0 mm/no pain, 100 mm/extreme pain. The location and depth of the injected fluid was assessed through 2D ultrasound echography images. Results: Viscosity levels had significant impact on perceived injection pain (P=0.0003. Specifically, less pain was associated with high viscosity (VAS =12.6 mm than medium (VAS =16.6 mm or low (VAS =22.1 mm viscosities, with a significant difference between high and low viscosities (P=0.0002. Target injection volume of 2 or 3 mL was demonstrated to have no significant impact on perceived injection pain (P=0.89. Slow (0.02 mL/s or fast (0.30 mL/s injection rates also showed no significant impact on perceived pain during SC injection (P=0.79. In 92% of injections, the injected fluid was located exclusively in SC tissue whereas the remaining injected fluids were found located in SC and/or intradermal layers. Conclusion: The results of this study suggest that solutions of up to 3 mL and up to 15–20 cP injected into the abdomen within 10 seconds are well tolerated without pain. High
Uauy, Ricardo; Corvalan, Camila; Casanello, Paola; Kuzanovic, Juan
2013-01-01
The need to prevent low birthweight (LBW) defined as a birthweight ≤2,500 g is presently well recognized, not only because of the immediate consequences increasing the risk of neonatal death and burden of disease but also in terms of the impact of being LBW on lifelong health and well-being. Children are born LBW (<2,500 g) either because they were born too early (true preterm LBW infants) or alternatively they failed to grow adequately despite a normal duration of gestation (intrauterine growth retardation IUGR). In this later case, the weight may be over 2,500 g, but the infant is lighter than expected for his/her gestational age. In fact, many preterm infants are to some degree growth retarded. Despite the differences in origin, all LBW categories are considered at increased risk of neonatal death and later morbidity. Preventive actions are more likely to succeed if we consider the nutritional interventions as part of a package that addresses in a holistic manner the full spectrum of needs of women from before conception as well as during pregnancy. We have gained sufficient experience with single nutrient and/or 'magic bullet' approaches to learn from this and avoid them in the future. New fetal growth standards (INTERGROWTH 2012) represent major progress in terms of evaluating the effect of early life events on later growth, health and well-being. Thus, for the first time, clinicians and researchers will have sequential longitudinal data that will serve to characterize whole body as well as brain, liver, and long bone growth, relating this indirectly to placental blood flow and transfer function, neonatal health, morbidity and mortality. Copyright © 2013 Nestec Ltd., Vevey/S. Karger AG, Basel.
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Donald P Bernstein
2010-01-01
Full Text Available Impedance cardiography (ICG is a branch of bioimpedance pimarily concerned with the determination of left ventricular stroke volume (SV. As implemented, using the transthoracic approach, the technique involves applying a current field longitudinally across a segment of thorax by means of a constant magnitude, high frequency, low amplitude alternating current (AC. By Ohm's Law, the voltage difference measured within the current field is proportional to the electrical impedance Z (Ω. Without ventilatory or cardiac activity, Z is known as the transthoracic, static base impedance Z0. Upon ventricular ejection, a characteristic time dependent cardiac-synchronous pulsatile impedance change is obtained, ΔZ(t, which, when placed electrically in parallel with Z0, constitutes the time-variable total transthoracic impedance Z(t. ΔZ(t represents a dual-element composite waveform, which comprises both the radially-oriented volumetric expansion of and axially-directed forward blood flow within both great thoracic arteries. In its majority, however, ΔZ(t is known to primarily emanate from the ascending aorta. Conceptually, commonly implemented methods assume a volumetric origin for the peak systolic upslope of ΔZ(t, (i.e. dZ/dtmax, with the presumed units of Ω·s-1. A recently introduced method assumes the rapid ejection of forward flowing blood in earliest systole causes significant changes in the velocity-induced blood resistivity variation (Δρb(t, Ωcm·s-1, and it is the peak rate of change of the blood resistivity variation dρb(t/dtmax (Ωcm·s-2 that is the origin of dZ/dtmax. As a consequence of dZ/dtmax peaking in the time domain of peak aortic blood acceleration, dv/dtmax (cm·s-2, it is suggested that dZ/dtmax is an ohmic mean acceleration analog (Ω·s-2 and not a mean flow or velocity surrogate as generally assumed. As conceptualized, the normalized value, dZ/dtmax/Z0, is a dimensionless ohmic mean acceleration equivalent (s-2
Kainerstorfer, Jana M.; Sassaroli, Angelo; Fantini, Sergio
2016-10-01
We present a quantitative analysis of dynamic diffuse optical measurements to obtain oxygen saturation of hemoglobin in volume oscillating compartments. We used a phasor representation of oscillatory hemodynamics at the heart rate and respiration frequency to separate the oscillations of tissue concentrations of oxyhemoglobin (O) and deoxyhemoglobin (D) into components due to blood volume (subscript V) and blood flow (subscript F): O=OV+OF, D=DV+DF. This is achieved by setting the phase angle Arg(OF)-Arg(O), which can be estimated by a hemodynamic model that we recently developed. We found this angle to be -72 deg for the cardiac pulsation at 1 Hz, and -7 deg for paced breathing at 0.1 Hz. Setting this angle, we can obtain the oxygen saturation of hemoglobin of the volume-oscillating vascular compartment, SV=|OV|/(|OV|+|DV|). We demonstrate this approach with cerebral near-infrared spectroscopy measurements on healthy volunteers at rest (n=4) and during 0.1 Hz paced breathing (n=3) with a 24-channel system. Rest data at the cardiac frequency were used to calculate the arterial saturation, S(a); over all subjects and channels, we found ==0.96±0.02. In the case of paced breathing, we found =0.66±0.14, which reflects venous-dominated hemodynamics at the respiratory frequency.
Treating network junctions in finite volume solution of transient gas flow models
Bermúdez, Alfredo; López, Xián; Vázquez-Cendón, M. Elena
2017-09-01
A finite volume scheme for the numerical solution of a non-isothermal non-adiabatic compressible flow model for gas transportation networks on non-flat topography is introduced. Unlike standard Euler equations, the model takes into account wall friction, variable height and heat transfer between the pipe and the environment which are source terms. The case of one single pipe was considered in a previous reference by the authors, [8], where a finite volume method with upwind discretization of the flux and source terms has been proposed in order to get a well-balanced scheme. The main goal of the present paper is to go a step further by considering a network of pipes. The main issue is the treatment of junctions for which container-like 2D finite volumes are introduced. The couplings between pipes (1D) and containers (2D) are carefully described and the conservation properties are analyzed. Numerical tests including real gas networks are solved showing the performance of the proposed methodology.
Determination of volume fractions in two-phase flows from sound speed measurement
Energy Technology Data Exchange (ETDEWEB)
Chaudhuri, Anirban [Los Alamos National Laboratory; Sinha, Dipen N. [Los Alamos National Laboratory; Osterhoudt, Curtis F. [University of Alaska
2012-08-15
Accurate measurement of the composition of oil-water emulsions within the process environment is a challenging problem in the oil industry. Ultrasonic techniques are promising because they are non-invasive and can penetrate optically opaque mixtures. This paper presents a method of determining the volume fractions of two immiscible fluids in a homogenized two-phase flow by measuring the speed of sound through the composite fluid along with the instantaneous temperature. Two separate algorithms are developed by representing the composite density as (i) a linear combination of the two densities, and (ii) a non-linear fractional formulation. Both methods lead to a quadratic equation with temperature dependent coefficients, the root of which yields the volume fraction. The densities and sound speeds are calibrated at various temperatures for each fluid component, and the fitted polynomial is used in the final algorithm. We present results when the new algorithm is applied to mixtures of crude oil and process water from two different oil fields, and a comparison of our results with a Coriolis meter; the difference between mean values is less than 1%. Analytical and numerical studies of sensitivity of the calculated volume fraction to temperature changes and calibration errors are also presented.
Shan, Xiaoyi; Chen, Fangfang; Wang, Wenpeng; Zhao, Juan; Teng, Yue; Wu, Minghui; Teng, Honghong; Zhang, Xue; Qi, Hong; Liu, Xiaohong; Tan, Chunying; Mi, Jie
2014-01-01
Background Information tracking changes of birthweight is scarce in China. To examine trends of low birthweight (birthweight < 2500 g) and macrosomia (birthweight ≥ 4000 g) and potential risk factors in Beijing, hospital records from two major obstetrics and gynecology hospitals in urban districts in Beijing were analyzed. Methods Hospital records from 1996 to 2010 were retrieved. Information of prenatal examination and birth outcomes was entered into a structured database. Live births were u...
DEFF Research Database (Denmark)
Mortensen, Laust H; Diderichsen, Finn; Smith, George Davey
2009-01-01
Maternal education is associated with the birthweight of offspring. We sought to quantify the role of maternal body mass index (BMI) and smoking as intermediary variables between maternal education and birthweight at term.......Maternal education is associated with the birthweight of offspring. We sought to quantify the role of maternal body mass index (BMI) and smoking as intermediary variables between maternal education and birthweight at term....
Effect of in vitro culture of human embryos on birthweight of newborns
Dumoulin, John C.; Land, Jolande A.; Van Montfoort, Aafke P.; Nelissen, Ewka C.; Coonen, Edith; Derhaag, Josien G.; Schreurs, Inge L.; Dunselman, Gerard A.; Kester, Arnold D.; Geraedts, Joep P.; Evers, Johannes L.
In animal models, in vitro culture of preimplantation embryos has been shown to be a risk factor for abnormal fetal outcome, including high and low birthweight. In the human, mean birthweight of singletons after in vitro fertilization (IVF) is considerably lower than after natural conception, but it
Effect of in vitro culture of human embryos on birthweight of newborns
Dumoulin, John C.; Land, Jolande A.; Van Montfoort, Aafke P.; Nelissen, Ewka C.; Coonen, Edith; Derhaag, Josien G.; Schreurs, Inge L.; Dunselman, Gerard A.; Kester, Arnold D.; Geraedts, Joep P.; Evers, Johannes L.
2010-01-01
In animal models, in vitro culture of preimplantation embryos has been shown to be a risk factor for abnormal fetal outcome, including high and low birthweight. In the human, mean birthweight of singletons after in vitro fertilization (IVF) is considerably lower than after natural conception, but it
Energy Technology Data Exchange (ETDEWEB)
Carneiro, Angelo; Byrne, James V. [ohn Radcliffe Hospital, Oxford Neurovascular and Neuroradiology Research Unit, Nuffield Department of Surgical Sciences, Oxford (United Kingdom); Rane, Neil; Kueker, Wilhelm; Cellerini, Martino; Corkill, Rufus [John Radcliffe Hospital, Department of Neuroradiology, Oxford (United Kingdom)
2014-01-15
This study assessed volume changes of unruptured large and giant aneurysms (greatest diameter >20 mm) after treatment with flow diverter (FD) stents. Clinical audit of the cases treated in a single institution, over a 5-year period. Demographic and clinical data were retrospectively collected from the hospital records. Aneurysm volumes were measured by manual outlining at sequential slices using computerised tomography (CT) or magnetic resonance (MR) angiography data. The audit included eight patients (seven females) with eight aneurysms. Four aneurysms involved the cavernous segment of the internal carotid artery (ICA), three the supraclinoid ICA and one the basilar artery. Seven patients presented with signs and symptoms of mass effect and one with seizures. All but one aneurysm was treated with a single FD stent; six aneurysms were also coiled (either before or simultaneously with FD placement). Minimum follow-up time was 6 months (mean 20 months). At follow-up, three aneurysms decreased in size, three were unchanged and two increased. Both aneurysms that increased in size showed persistent endosaccular flow at follow-up MR; in one case, failure was attributed to suboptimal position of the stent; in the other case, it was attributed to persistence of a side branch originating from the aneurysm (similar to the endoleak phenomenon of aortic aneurysms). At follow-up, five aneurysms were completely occluded; none of these increased in volume. Complete occlusion of the aneurysms leads, in most cases, to its shrinkage. In cases of late aneurysm growth or regrowth, consideration should be given to possible endoleak as the cause. (orig.)
Brito, Aline de Freitas; de Oliveira, Caio Victor Coutinho; Brasileiro-Santos, Maria do Socorro; Santos, Amilton da Cruz
2014-01-01
The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects. The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m(2)) subjected to three experimental sessions, ie, a control session, exercise with a set (S1), and exercise with three sets (S3). For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention) in the supine position. Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, -26.5±4.2 mmHg versus -17.9±4.7 mmHg; diastolic blood pressure, -13.8±4.9 mmHg versus -7.7±5 mmHg, Pexercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular resistance.
Parental diabetes and birthweight in 236 030 individuals in the UK Biobank Study
Tyrrell, Jessica S; Yaghootkar, Hanieh; Freathy, Rachel M; Hattersley, Andrew T; Frayling, Timothy M
2013-01-01
Background The UK Biobank study provides a unique opportunity to study the causes and consequences of disease. We aimed to use the UK Biobank data to study the well-established, but poorly understood, association between low birthweight and type 2 diabetes. Methods We used logistic regression to calculate the odds ratio for participants’ risk of type 2 diabetes given a one standard deviation increase in birthweight. To test for an association between parental diabetes and birthweight, we performed linear regression of self-reported parental diabetes status against birthweight. We performed path and mediation analyses to test the hypothesis that birthweight partly mediates the association between parental diabetes and participant type 2 diabetes status. Results Of the UK Biobank participants, 277 261 reported their birthweight. Of 257 715 individuals of White ethnicity and singleton pregnancies, 6576 had type 2 diabetes, 19 478 reported maternal diabetes (but not paternal), 20 057 reported paternal diabetes (but not maternal) and 2754 participants reported both parents as having diabetes. Lower birthweight was associated with type 2 diabetes in the UK Biobank participants. A one kilogram increase in birthweight was associated with a lower risk of type 2 diabetes (odds ratio: 0.74; 95% CI: 0.71, 0.76; P = 2 × 10−57). Paternal diabetes was associated with lower birthweight (45 g lower; 95% CI: 36, 54; P = 2 × 10−23) relative to individuals with no parental diabetes. Maternal diabetes was associated with higher birthweight (59 g increase; 95% CI: 50, 68; P = 3 × 10−37). Participants’ lower birthweight was a mediator of the association between reported paternal diabetes and participants’ type 2 diabetes status, explaining 1.1% of the association, and participants’ higher birthweight was a mediator of the association between reported maternal diabetes and participants’ type 2 diabetes status, explaining 1.2% of the association. Conclusions Data from
Regional Myocardial Blood Volume and Flow: First-Pass MR Imaging with Polylysine-Gd-DTPA
Wilke, Norbert; Kroll, Keith; Merkle, Hellmut; Wang, Ying; Ishibashi, Yukata; Xu, Ya; Zhang, Jiani; Jerosch-Herold, Michael; Mühler, Andreas; Stillman, Arthur E.; Bassingthwaighte, James B.; Bache, Robert; Ugurbil, Kamil
2010-01-01
The authors investigated the utility of an intravascular magnetic resonance (MR) contrast agent, poly-L-lysine-gadolinium diethylenetriaminepentaacetic acid (DTPA), for differentiating acutely ischemic from normally perfused myocardium with first-pass MR imaging. Hypoperfused regions, identified with microspheres, on the first-pass images displayed significantly decreased signal intensities compared with normally perfused myocardium (P < .0007). Estimates of regional myocardial blood content, obtained by measuring the ratio of areas under the signal intensity-versus-time curves in tissue regions and the left ventricular chamber, averaged 0.12 mL/g ± 0.04 (n = 35), compared with a value of 0.11 mL/g ± 0.05 measured with radiolabeled albumin in the same tissue regions. To obtain MR estimates of regional myocardial blood flow, in situ calibration curves were used to transform first-pass intensity-time curves into content-time curves for analysis with a multiple-pathway, axially distributed model. Flow estimates, obtained by automated parameter optimization, averaged 1.2 mL/min/g ± 0.5 [n = 29), compared with 1.3 mL/min/g ± 0.3 obtained with tracer microspheres in the same tissue specimens at the same time. The results represent a combination of T1-weighted first-pass imaging, intravascular relaxation agents, and a spatially distributed perfusion model to obtain absolute regional myocardial blood flow and volume. PMID:7766986
Directory of Open Access Journals (Sweden)
M. S. Adams
2016-06-01
Full Text Available Debris flows cause an average € 30 million damages and 1-2 fatalities every year in Austria. Detailed documentation of their extent and magnitude is essential for understanding, preventing and mitigating these natural hazard events. The recent development of unmanned aerial systems (UAS has provided a new possibility for on-demand high-resolution monitoring and mapping. Here, we present a study, where the spatial extent and volume of a large debris flow event were mapped with different UAS, fitted with commercial off-the-shelf sensors. Orthophotos and digital terrain models (DTM were calculated using structure-from-motion photogrammetry software. Terrain height differences caused by the debris flow in the catchment and valley floor were derived by subtracting the pre-event airborne laser scanning (ALS DTM from a post-event UAS-DTM. The analysis of the volumetric sediment budget showed, that approximately 265,000 m³ material was mobilised in the catchment, of which 45,000 m³ settled there; of the material, which reached the valley floor, 120,000 m³ was deposited, while another 10,000 m³ was eroded from there. The UAS-results were validated against ALS data and imagery from a traditional manned-aircraft photogrammetry campaign. In conclusion, the UAS-data can reach an accuracy and precision comparable to manned aircraft data, but with the added benefits of higher flexibility, easier repeatability, less operational constraints and higher spatial resolution.
Bürger, Raimund; Kumar, Sarvesh; Ruiz-Baier, Ricardo
2015-10-01
The sedimentation-consolidation and flow processes of a mixture of small particles dispersed in a viscous fluid at low Reynolds numbers can be described by a nonlinear transport equation for the solids concentration coupled with the Stokes problem written in terms of the mixture flow velocity and the pressure field. Here both the viscosity and the forcing term depend on the local solids concentration. A semi-discrete discontinuous finite volume element (DFVE) scheme is proposed for this model. The numerical method is constructed on a baseline finite element family of linear discontinuous elements for the approximation of velocity components and concentration field, whereas the pressure is approximated by piecewise constant elements. The unique solvability of both the nonlinear continuous problem and the semi-discrete DFVE scheme is discussed, and optimal convergence estimates in several spatial norms are derived. Properties of the model and the predicted space accuracy of the proposed formulation are illustrated by detailed numerical examples, including flows under gravity with changing direction, a secondary settling tank in an axisymmetric setting, and batch sedimentation in a tilted cylindrical vessel.
A New Efficient Finite Volume Modeling of Small Amplitude Free Surface Flows with Unstructured Grid
Institute of Scientific and Technical Information of China (English)
L(U) Biao
2013-01-01
A staggered finite-volume technique for non-hydrostatic,small amplitude free surface flow governed by the incompressible Navier-Stokes equations is presented there is a proper balance between accuracy and computing time.The advection and horizontal diffusion terms in the momentum equation are discretized by an integral interpolation method on the orthogonal unstructured staggered mesh and,while it has the attractive property of being conservative.The pressure-correction algorithm is employed for the non-hydrostatic pressure in order to achieve second-order temporal accuracy.A conservative scalar transport algorithm is also applied to discretize k-ε equations in this model.The eddy viscosity is calculated from the k-ε turbulent model.The resulting model is mass and momentum conservative.The model is verified by two examples to simulate unsteady small amplitude free surface flows where non-hydrostatic pressures have a considerable effect on the velocity field,and then applied to simulate the tidal flow in the Bohai Sea.
Fetal growth versus birthweight: the role of placenta versus other determinants.
Directory of Open Access Journals (Sweden)
Marie Cecilie Paasche Roland
Full Text Available INTRODUCTION: Birthweight is used as an indicator of intrauterine growth, and determinants of birthweight are widely studied. Less is known about determinants of deviating patterns of growth in utero. We aimed to study the effects of maternal characteristics on both birthweight and fetal growth in third trimester and introduce placental weight as a possible determinant of both birthweight and fetal growth in third trimester. METHODS: The STORK study is a prospective cohort study including 1031 healthy pregnant women of Scandinavian heritage with singleton pregnancies. Maternal determinants (age, parity, body mass index (BMI, gestational weight gain and fasting plasma glucose of birthweight and fetal growth estimated by biometric ultrasound measures were explored by linear regression models. Two models were fitted, one with only maternal characteristics and one which included placental weight. RESULTS: Placental weight was a significant determinant of birthweight. Parity, BMI, weight gain and fasting glucose remained significant when adjusted for placental weight. Introducing placental weight as a covariate reduced the effect estimate of the other variables in the model by 62% for BMI, 40% for weight gain, 33% for glucose and 22% for parity. Determinants of fetal growth were parity, BMI and weight gain, but not fasting glucose. Placental weight was significant as an independent variable. Parity, BMI and weight gain remained significant when adjusted for placental weight. Introducing placental weight reduced the effect of BMI on fetal growth by 23%, weight gain by 14% and parity by 17%. CONCLUSION: In conclusion, we find that placental weight is an important determinant of both birthweight and fetal growth. Our findings indicate that placental weight markedly modifies the effect of maternal determinants of both birthweight and fetal growth. The differential effect of third trimester glucose on birthweight and growth parameters illustrates that
Ventriculomegaly in very-low-birthweight infants with Down syndrome.
Movsas, Tammy Z; Spitzer, Alan R; Gewolb, Ira H
2016-11-01
The prevalence of Down syndrome in infants with fetal ventriculomegaly is 5% to 10%; however, the converse, the prevalence of cerebral ventriculomegaly in live-born infants with Down syndrome, is not well established. Because cranial ultrasounds are performed on most very-low-birthweight (VLBW) infants (birthweight Down syndrome, and whether VLBW infants with Down syndrome are at higher risk for cranial ultrasound abnormalities, compared with the already elevated risk in other VLBW infants. This study comprised retrospective analysis of data from Pediatrix BabySteps Clinical Data Warehouse. The study population consisted of 121 736 VLBW infants (61 869 males, 59 867 females), born between 1996 and 2013, of whom 441 had Down syndrome (233 males, 208 females; mean gestational age 30wks, standard deviation [SD] 2.8wks). Logistic regression was used to calculate odds of ventriculomegaly and IVH for Down syndrome. Prevalence of ventriculomegaly in Down syndrome was 5.2% compared with 0.8% in other VLBW infants. Multivariate analysis indicated 5.8× odds (95% confidence interval [CI] 3.4-9.7) of ventriculomegaly in Down syndrome and 0.9× odds (95% CI 0.7-1.1) of IVH for Down syndrome. Very preterm infants with Down syndrome are at increased risk for ventriculomegaly (but not for IVH) compared with other infants born very preterm. © 2016 Mac Keith Press.
Increased enamel hypoplasia and very low birthweight infants.
Nelson, S; Albert, J M; Geng, C; Curtan, S; Lang, K; Miadich, S; Heima, M; Malik, A; Ferretti, G; Eggertsson, H; Slayton, R L; Milgrom, P
2013-09-01
Birth cohort studies of developmental defects of enamel (DDE) and early childhood caries (ECC) in very low birthweight (VLBW) and normal birthweight (NBW) infants are rare. In this birth cohort of 234 VLBW and 234 NBW infants, we report the incidence of ECC and DDE at 8 and 18-20 mos of corrected age. Infant medical and maternal socio-demographic data were abstracted from medical records at birth. Dental assessments for ECC and DDE (enamel hypoplasia, demarcated and diffuse opacities) were completed at 8 and 18-20 mos. The incidence of hypoplasia was significantly higher in VLBW compared with NBW infants (8 mos, 19% vs. 2%; 18 mos, 31% vs. 8%). The incidence of ECC (International Caries Detection and Assessment System: ICDAS ≥ 2) was 1.4% (8 mos) and 12% (18-20 mos) and was similar between the VLBW and NBW groups. At both ages, using a beta-binomial regression model to control for potential confounders (maternal and infant characteristics), we found increased risk for enamel hypoplasia among the VLBW infants compared with the NBW infants. African Americans had a lower risk for enamel hypoplasia at 18-20 mos. The VLBW infants should be monitored for ECC due to the presence of enamel hypoplasia.
Institute of Scientific and Technical Information of China (English)
Gang Guo; Yonggui Yang; Weiqun Yang
2011-01-01
This study investigated the effect of velocity encoding on measurement of brain blood flow and blood volume of inflow and outflow using phase-contrast magnetic resonance angiography. A single two-dimensional phase-contrast magnetic resonance angiography slice was applied perpendicular to the internal carotid artery and the vertebral artery at C2 level. For each subject, the velocity encoding was set from 30 to 90 cm/s with an interval of 10 cm/s for a total of seven settings. Various velocity encodings greatly affected blood flow volume, maximal blood flow velocity and mean blood flow velocity in the internal carotid artery, but did not significantly affect vertebral arteries and jugular veins. When velocity encoding was 60-80 cm/s, the inflow blood volume was 655 ± 118 mL/min, and the outflow volume was 506 ± 186 mL/min. The ratio of outflow/inflow was steady at 0.78-0.83, and there was no aliasing in any of the images. These findings suggest that velocity encodings of 60-80 cm/s should be selected during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography.
Berteau, Cecile; Filipe-Santos, Orchidée; Wang, Tao; Rojas, Humberto E; Granger, Corinne; Schwarzenbach, Florence
2015-01-01
The primary objective of this study was to evaluate the impact of fluid injection viscosity in combination with different injection volumes and flow rates on subcutaneous (SC) injection pain tolerance. The study was a single-center, comparative, randomized, crossover, Phase I study in 24 healthy adults. Each participant received six injections in the abdomen area of either a 2 or 3 mL placebo solution, with three different fluid viscosities (1, 8-10, and 15-20 cP) combined with two different injection flow rates (0.02 and 0.3 mL/s). All injections were performed with 50 mL syringes and 27G, 6 mm needles. Perceived injection pain was assessed using a 100 mm visual analog scale (VAS) (0 mm/no pain, 100 mm/extreme pain). The location and depth of the injected fluid was assessed through 2D ultrasound echography images. Viscosity levels had significant impact on perceived injection pain (P=0.0003). Specifically, less pain was associated with high viscosity (VAS =12.6 mm) than medium (VAS =16.6 mm) or low (VAS =22.1 mm) viscosities, with a significant difference between high and low viscosities (P=0.0002). Target injection volume of 2 or 3 mL was demonstrated to have no significant impact on perceived injection pain (P=0.89). Slow (0.02 mL/s) or fast (0.30 mL/s) injection rates also showed no significant impact on perceived pain during SC injection (P=0.79). In 92% of injections, the injected fluid was located exclusively in SC tissue whereas the remaining injected fluids were found located in SC and/or intradermal layers. The results of this study suggest that solutions of up to 3 mL and up to 15-20 cP injected into the abdomen within 10 seconds are well tolerated without pain. High viscosity injections were shown to be the most tolerated, whereas injection volume and flow rates did not impact perceived pain.
Directory of Open Access Journals (Sweden)
Fabiana Paiva Martins
2013-09-01
Full Text Available Objective To investigate superior mesenteric artery flow measurement by Doppler ultrasonography as a means of characterizing inflammatory activity in Crohn's disease. Materials and Methods Forty patients were examined and divided into two groups – disease activity and remission – according to their Crohn's disease activity index score. Mean superior mesenteric artery flow volume was calculated for each group and correlated with Crohn's disease activity index score. Results The mean superior mesenteric artery flow volume was significantly greater in the patients with active disease (626 ml/min ± 236 × 376 ml/min ± 190; p = 0.001. As a cut off corresponding to 500 ml/min was utilized, the superior mesenteric artery flow volume demonstrated sensitivity of 83% and specificity of 82% for the diagnosis of Crohn's disease activity. Conclusion The present results suggest that patients with active Crohn's disease have increased superior mesenteric artery flow volume as compared with patients in remission. Superior mesenteric artery flow measurement had a good performance in the assessment of disease activity in this study sample.
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Brito AF
2014-12-01
Full Text Available Aline de Freitas Brito,1 Caio Victor Coutinho de Oliveira,2 Maria do Socorro Brasileiro-Santos,1 Amilton da Cruz Santos1 1Physical Education Department, 2Research Laboratory for Physical Training Applied to Performance and Health, Federal University of Paraíba, João Pessoa, Brazil Background: The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects.Methods: The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m2 subjected to three experimental sessions, ie, a control session, exercise with a set (S1, and exercise with three sets (S3. For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention in the supine position.Results: Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, −26.5±4.2 mmHg versus −17.9±4.7 mmHg; diastolic blood pressure, −13.8±4.9 mmHg versus −7.7±5 mmHg, P<0.05. Similarly, forearm blood flow and forearm vascular resistance changed significantly in both sessions with an increase and decrease, respectively, that was more evident in S3 than in S1 (P<0.05.Conclusion: Resistance exercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular
A new numerical framework to simulate viscoelastic free-surface flows with the finite-volume method
DEFF Research Database (Denmark)
Comminal, Raphaël; Spangenberg, Jon; Hattel, Jesper Henri
A new method for the simulation of 2D viscoelastic flow is presented. Numerical stability is obtained by the logarithmic-conformation change of variable, and a fully-implicit pure-streamfunction flow formulation, without use of any artificial diffusion. As opposed to other simulation results, our...... calculations predict a hydrodynamic instability in the 4:1 contraction geometry at a Weissenberg number of order 4. This new result is in qualitative agreement with the prediction of a non-linear subcritical elastic instability in Poiseuille flow. Our viscoelastic flow solver is coupled with a volume...
A new numerical framework to simulate viscoelastic free-surface flows with the finite-volume method
DEFF Research Database (Denmark)
Comminal, Raphaël; Spangenberg, Jon; Hattel, Jesper Henri
2015-01-01
A new method for the simulation of 2D viscoelastic flow is presented. Numerical stability is obtained by the logarithmic-conformation change of variable, and a fully-implicit pure-streamfunction flow formulation, without use of any artificial diffusion. As opposed to other simulation results, our...... calculations predict a hydrodynamic instability in the 4:1 contraction geometry at a Weissenberg number of order 4. This new result is in qualitative agreement with the prediction of a non-linear subcritical elastic instability in Poiseuille flow. Our viscoelastic flow solver is coupled with a volume...
Finite volume methods for submarine debris flow with Herschel-Bulkley rheology
Kim, Jihwan; Issler, Dieter
2015-04-01
Submarine landslides can impose great danger to the underwater structures and generate destructive waves. The Herschel-Bulkley rheological model is known to be appropriate for describing the nonlinear viscoplastic behavior of the debris flow. The numerical implementation of the depth-averaged Herschel-Bulkley models such as BING has so-far been limited to the 1-dimensional Lagrangian coordinate system. In this work, we develop numerical schemes with the finite volume methods in the Eulerian coordinates. We provide parameter sensitivity analysis and demonstrate how common ad-hoc assumptions such as including a minimum shear layer depth influence the modeling of the landslide dynamics. The possibility of adding hydrodynamic resistance forces, hydroplaning, and remolding into this Eulerian framework is also discussed. Finally, the possible extension to a two-dimensional operational model for coupling towards operational tsunami models is discussed.
Control theory based airfoil design for potential flow and a finite volume discretization
Reuther, J.; Jameson, A.
1994-01-01
This paper describes the implementation of optimization techniques based on control theory for airfoil design. In previous studies it was shown that control theory could be used to devise an effective optimization procedure for two-dimensional profiles in which the shape is determined by a conformal transformation from a unit circle, and the control is the mapping function. The goal of our present work is to develop a method which does not depend on conformal mapping, so that it can be extended to treat three-dimensional problems. Therefore, we have developed a method which can address arbitrary geometric shapes through the use of a finite volume method to discretize the potential flow equation. Here the control law serves to provide computationally inexpensive gradient information to a standard numerical optimization method. Results are presented, where both target speed distributions and minimum drag are used as objective functions.
Second-order accurate finite volume method for well-driven flows
Dotlić, Milan; Pokorni, Boris; Pušić, Milenko; Dimkić, Milan
2013-01-01
We consider a finite volume method for a well-driven fluid flow in a porous medium. Due to the singularity of the well, modeling in the near-well region with standard numerical schemes results in a completely wrong total well flux and an inaccurate hydraulic head. Local grid refinement can help, but it comes at computational cost. In this article we propose two methods to address well singularity. In the first method the flux through well faces is corrected using a logarithmic function, in a way related to the Peaceman correction. Coupling this correction with a second-order accurate two-point scheme gives a greatly improved total well flux, but the resulting scheme is still not even first order accurate on coarse grids. In the second method fluxes in the near-well region are corrected by representing the hydraulic head as a sum of a logarithmic and a linear function. This scheme is second-order accurate.
Classification of pulmonary system diseases patterns using flow-volume curve.
Arabalibeik, Hossein; Jafari, Samaneh; Agin, Khosro
2011-01-01
Spirometry is the most common pulmonary function test. It provides useful information for early detection of respiratory system abnormalities. While decision support systems use normally calculated parameters such as FEV1, FVC, and FEV1% to diagnose the pattern of respiratory system diseases, expert physicians pay close attention to the pattern of the flow-volume curve as well. Fisher discriminant analysis shows that coefficients of a simple polynomial function fitted to the curve, can capture the information about the disease patterns much better than the familiar single point parameters. A neural network then can classify the abnormality pattern as restrictive, obstructive, mixed, or normal. Using the data from 205 adult volunteers, total accuracy, sensitivity and specificity for four categories are 97.6%, 97.5% and 98.8% respectively.
Timofeev, Evgeny; Norouzi, Farhang
2016-06-01
The motivation for using hybrid, explicit-implicit, schemes rather than fully implicit or explicit methods for some unsteady high-speed compressible flows with shocks is firstly discussed. A number of such schemes proposed in the past are briefly overviewed. A recently proposed hybridization approach is then introduced and used for the development of a hybrid, explicit-implicit, TVD (Total Variation Diminishing) scheme of the second order in space and time on smooth solutions in both, explicit and implicit, modes for the linear advection equation. Further generalizations of this finite-volume method for the Burgers, Euler and Navier-Stokes equations discretized on unstructured grids are mentioned in the concluding remarks.
A time-of-flight flow sensor for the volume measurement of trace amount of interstitial fluid
Yu, H.; Li, D.; Roberts, R. C.; Xu, K.; Tien, N. C.
2012-05-01
Transdermal extraction of interstitial fluid (ISF) offers an attractive method for noninvasive blood glucose monitoring. The existing macroscale systems are not suitable for ISF collection, mainly because of the minute volume of the transdermally extracted ISF which scatters on the skin surface. Human skin's low permeability to glucose and its varying permeability exemplify the crucial need to make precise ISF volume measurements in order to calculate blood glucose concentrations accurately. In this paper, we present a novel time-of-flight flow sensor consisting of four electrode pairs fabricated directly into the channel of a polydimethylsiloxane (PDMS) microfluidic device designed to accurately measure the volume of transdermally extracted ISF. As fluid traverses the channel, it bridges each electrode pair and changes its resistance. By measuring the time difference in resistance change between each electrode pair, a precise fluid volume can be measured. In order to verify the suitability of the sensor for biological applications, experiments were conducted using a normal saline solution which is similar to ISF. The stability of the sensor was tested using a fixed volume, and the coefficient of variation for 20 tests was determined to be 0.0041. The consistency of the sensor for varied volume measurements was shown by the high correlation coefficient (R2 = 0.9992) between the tested volume and the volume measured by a commercial micro syringe. The excellent functionality of the flow sensor can be extended toward the measurement of conductive chemical and biochemical buffers and reagents.
Volume of Fluid (VOF) type advection methods in two-phase flow: a comparative study
Aniszewski, Wojciech; Marek, Maciej
2014-01-01
In this paper, four distinct approaches to Volume of Fluid (VOF) computational method are compared. Two of the methods are the 'simplified' VOF formulations, in that they do not require geometrical interface reconstruction. The assessment is made possible by implementing all four approaches into the same code as a switchable options. This allows to rule out possible influence of other parts of numerical scheme, be it the discretisation of Navier-Stokes equations or chosen approximation of curvature, so that we are left with conclusive arguments because only one factor differs the compared methods. The comparison is done in the framework of CLSVOF (Coupled Level Set Volume of Fluid), so that all four methods are coupled with Level Set interface, which is used to compute pressure jump via the GFM (Ghost-Fluid Method). Results presented include static advections, full N-S solutions in laminar and turbulent flows. The paper is aimed at research groups who are implementing VOF methods in their computations or inte...
Flux-splitting finite volume method for turbine flow and heat transfer analysis
Xu, C.; Amano, R. S.
A novel numerical method was developed to deal with the flow and heat transfer in a turbine cascade at both design and off-design conditions. The Navier-Stokes equations are discretized and integrated in a coupled manner. In the present method a time-marching scheme was employed along with the time-integration approach. The flux terms are discretized based on a cell finite volume formulation as well as a flux-difference splitting. The flux-difference splitting makes the scheme rapid convergence and the finite volume technique ensure the governing equations for the conservation of mass, momentum and energy. A hybrid difference scheme for quasi-three-dimensional procedure based on the discretized and integrated Navier-Stokes equations was incorporated in the code. The numerical method possesses the positive features of the explicit and implicit algorithms which provide a rapid convergence process and have a less stability constraint. The computed results were compared with other numerical studies and experimental data. The comparisons showed fairly good agreement with experiments.
Smooth reference equations for slow vital capacity and flow-volume curve indexes.
Pistelli, F; Bottai, M; Viegi, G; Di Pede, F; Carrozzi, L; Baldacci, S; Pedreschi, M; Giuntini, C
2000-03-01
We derived reference values for slow vital capacity (VC) and flow-volume curve indexes (FVC, FEV(1), and flows) from the 1,185 tracings provided by 1,039 "normal" subjects who participated in one or both cross-sectional surveys of the Po River Delta study in 1980-1982 and in 1988-1991. Definition of "normal" was based on negative answers to questions on respiratory symptoms/diseases or recent infections, current/past tobacco smoking, and work exposure to noxious agents. Reference equations were derived separately by sex as linear regressions of body mass index (BMI = weight/height(2)), BMI-squared, height, height-squared, and age. Age entered all the models by natural cubic splines using two break points, except for the ratios FEV(1)/VC and FEV(1)/FVC. Random effects models were applied to adjust for the potential intrasubject correlation. BMI, along with height and age, appeared to be an important predictor, which was significantly associated with VC, FEV(1), FVC, FEV(1)/FVC, and PEF in both sexes, and with FEV(1)/VC and FEF(25-75) in females. Natural cubic splines provided smooth reference equation curves (no "jumps" or "angled points") over the entire age span, differently from the conventional reference equations. Thus, we recommend the use of smooth continuous equations for predicting lung function indexes, along with the inclusion of BMI in the equations.
Quantitative measurements of cerebral blood flow in volume imaging PET scanners
Energy Technology Data Exchange (ETDEWEB)
Smith, R.J.; Shao, L.; Freifelder, R.; Karp, J.S.; Ragland, J.D. [Univ. of Pennsylvania, Philadelphia, PA (United States)
1995-08-01
Quantitative measurements of Cerebral Blood Flow (CBF) are performed in a volume imaging PET Scanner by means of moderate activity infusions. In equilibrium infusions, activations are measured by scanning over 10 minutes with 16 minute activations. Typical measured whole brain CBF values are 37{+-}8 ml/min/100g, close to the value of 42 ml/min/100g reported by other groups using this method. For ramped infusions, scanning over 4 minutes with 5 minute activations results in whole brain CBFs of 49 {+-} 9 ml/min/100g, close to the Kety and Schmidt value of 50 ml/min/100g. Both equilibrium and ramped infusion methods have been used to study face and word memory in human subjects. Both methods were able to detect significant activations in regions implicated in human memory. The authors conclude that precise quantitation of regional CBF is achieved using both methods, and that ramped infusions also provide accurate measures of CBF. In addition a simplified protocol for ramped infusion studies has been developed. In this method the whole brain tissue time activity curve generated from dynamic scanning is replaced by an appropriately scaled camera coincidence countrate curve. The resulting whole brain CBF values are only 7% different from the dynamic scan and fit results. Regional CBFs (rCBF) may then be generated from the summed image (4.25 minutes) using a count density vs flow lookup table.
Directory of Open Access Journals (Sweden)
Baranovskaya T. P.
2014-06-01
Full Text Available The article suggests a mathematical model of optimization of the volume of material flows: the model for the ideal conditions; the model for the working conditions; generalized model of determining the optimal input parameters. These models optimize such parameters of inventory management in technology-integrated grain production systems, as the number of cycles supply, the volume of the source material and financial flows. The study was carried out on the example of the integrated system of production, processing and sales of wheat (bread with the full technological cycle
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper, the feasibility of measuring the gas volume fraction in a mixed gas-liquid flow by using an acoustic resonant spectroscopy (ARS) method in a transient way is studied theoretically and experimentally. Firstly, the effects of sizes and locations of a single air bubble in a cylindrical cavity with two open ends on resonant frequencies are investigated numerically. Then, a transient measurement system for ARS is established, and the trends of the resonant frequencies (RFs) and resonant amplitudes (RAs) in the cylindrical cavity with gas flux inside are investigated experimentally. The measurement results by the proposed transient method are compared with those by steady-state ones and numerical ones. The numerical results show that the RFs of the cavity are highly sensitive to the volume of the single air bubble. A tiny bubble volume perturbation may cause a prominent RF shift even though the volume of the air bubble is smaller than 0.1% of that of the cavity. When the small air bubble moves, the RF shift will change and reach its maximum value as it is located at the middle of the cavity. As the gas volume fraction of the two-phase flow is low, both the RFs and RAs from the measurement results decrease dramatically with the increasing gas volume, and this decreasing trend gradually becomes even as the gas volume fraction increases further. These experimental results agree with the theoretical ones qualitatively. In addition, the transient method for ARS is more suitable for measuring the gas volume fraction with randomness and instantaneity than the steady-state one, because the latter could not reflect the random and instant characteristics of the mixed fluid due to the time consumption for frequency sweeping. This study will play a very important role in the quantitative measurement of the gas volume fraction of multiphase flows.
A finite-volume HLLC-based scheme for compressible interfacial flows with surface tension
Energy Technology Data Exchange (ETDEWEB)
Garrick, Daniel P. [Department of Aerospace Engineering, Iowa State University, Ames, IA (United States); Owkes, Mark [Department of Mechanical and Industrial Engineering, Montana State University, Bozeman, MT (United States); Regele, Jonathan D., E-mail: jregele@iastate.edu [Department of Aerospace Engineering, Iowa State University, Ames, IA (United States)
2017-06-15
Shock waves are often used in experiments to create a shear flow across liquid droplets to study secondary atomization. Similar behavior occurs inside of supersonic combustors (scramjets) under startup conditions, but it is challenging to study these conditions experimentally. In order to investigate this phenomenon further, a numerical approach is developed to simulate compressible multiphase flows under the effects of surface tension forces. The flow field is solved via the compressible multicomponent Euler equations (i.e., the five equation model) discretized with the finite volume method on a uniform Cartesian grid. The solver utilizes a total variation diminishing (TVD) third-order Runge–Kutta method for time-marching and second order TVD spatial reconstruction. Surface tension is incorporated using the Continuum Surface Force (CSF) model. Fluxes are upwinded with a modified Harten–Lax–van Leer Contact (HLLC) approximate Riemann solver. An interface compression scheme is employed to counter numerical diffusion of the interface. The present work includes modifications to both the HLLC solver and the interface compression scheme to account for capillary force terms and the associated pressure jump across the gas–liquid interface. A simple method for numerically computing the interface curvature is developed and an acoustic scaling of the surface tension coefficient is proposed for the non-dimensionalization of the model. The model captures the surface tension induced pressure jump exactly if the exact curvature is known and is further verified with an oscillating elliptical droplet and Mach 1.47 and 3 shock-droplet interaction problems. The general characteristics of secondary atomization at a range of Weber numbers are also captured in a series of simulations.
A finite-volume HLLC-based scheme for compressible interfacial flows with surface tension
Garrick, Daniel P.; Owkes, Mark; Regele, Jonathan D.
2017-06-01
Shock waves are often used in experiments to create a shear flow across liquid droplets to study secondary atomization. Similar behavior occurs inside of supersonic combustors (scramjets) under startup conditions, but it is challenging to study these conditions experimentally. In order to investigate this phenomenon further, a numerical approach is developed to simulate compressible multiphase flows under the effects of surface tension forces. The flow field is solved via the compressible multicomponent Euler equations (i.e., the five equation model) discretized with the finite volume method on a uniform Cartesian grid. The solver utilizes a total variation diminishing (TVD) third-order Runge-Kutta method for time-marching and second order TVD spatial reconstruction. Surface tension is incorporated using the Continuum Surface Force (CSF) model. Fluxes are upwinded with a modified Harten-Lax-van Leer Contact (HLLC) approximate Riemann solver. An interface compression scheme is employed to counter numerical diffusion of the interface. The present work includes modifications to both the HLLC solver and the interface compression scheme to account for capillary force terms and the associated pressure jump across the gas-liquid interface. A simple method for numerically computing the interface curvature is developed and an acoustic scaling of the surface tension coefficient is proposed for the non-dimensionalization of the model. The model captures the surface tension induced pressure jump exactly if the exact curvature is known and is further verified with an oscillating elliptical droplet and Mach 1.47 and 3 shock-droplet interaction problems. The general characteristics of secondary atomization at a range of Weber numbers are also captured in a series of simulations.
1D and 2D Numerical Modeling for Solving Dam-Break Flow Problems Using Finite Volume Method
Directory of Open Access Journals (Sweden)
Szu-Hsien Peng
2012-01-01
Full Text Available The purpose of this study is to model the flow movement in an idealized dam-break configuration. One-dimensional and two-dimensional motion of a shallow flow over a rigid inclined bed is considered. The resulting shallow water equations are solved by finite volumes using the Roe and HLL schemes. At first, the one-dimensional model is considered in the development process. With conservative finite volume method, splitting is applied to manage the combination of hyperbolic term and source term of the shallow water equation and then to promote 1D to 2D. The simulations are validated by the comparison with flume experiments. Unsteady dam-break flow movement is found to be reasonably well captured by the model. The proposed concept could be further developed to the numerical calculation of non-Newtonian fluid or multilayers fluid flow.
Raeini, Ali Q.; Bijeljic, Branko; Blunt, Martin J.
2015-09-01
We study capillary trapping in porous media using direct pore-scale simulation of two-phase flow on micro-CT images of a Berea sandstone and a sandpack. The trapped non-wetting phase saturations are predicted by solving the full Navier-Stokes equations using a volume-of-fluid based finite-volume framework to simulate primary drainage followed by water injection. Using these simulations, we analyse the effects of initial non-wetting-phase saturation, capillary number and flow direction on the residual saturation. The predictions from our numerical method are in agreement with published experimental measurements of capillary trapping curves. This shows that our direct simulation method can be used to elucidate the effect of pore structure and flow pattern of capillary trapping and provides a platform to study the physics of multiphase flow at the pore scale.
DEFF Research Database (Denmark)
Lauenborg, Jeannet; Jørgensen, Mie Kw; Damm, Peter
2011-01-01
Background. Links are well established between both family history of diabetes and reduced birthweight and increased risk of diabetes in adulthood. Objectives. 1) To investigate the influence of parental history of type 2 diabetes (T2DM) on offspring birthweight and adult offspring glucose...... with a spouse without known diabetes. Methods. Oral glucose tolerance tests and frequently sampled intravenous glucose tolerance tests (FSIGT) in non-diabetic offspring. Birthweight and length obtained from birth records. Results. Among 122 offspring with maternal history of T2DM, 14.8% had diabetes compared...
Anxiety in adolescents born preterm or with very low birthweight
DEFF Research Database (Denmark)
Sømhovd, Mikael Julius; Hansen, Bo Mølholm; Brok, Jesper Sune
2012-01-01
Aim To determine if adolescents who are born very preterm (anxiety problems. Method We used a systematic review and meta-analysis. We searched the databases ISI Web...... of identified articles. We selected casecontrol studies of adolescents 11 to 20 years old who were very preterm/VLBW and had a matched reference group born at term with normal birthweight that reported a validated anxiety outcome measure. For data extraction, two authors independently reviewed titles, abstracts......, and full articles identified through the searches. Subsequently two authors independently extracted data. Results We included six studies with 1519 adolescents (787 very preterm/VLBW, 732 comparisons). The general risk of developing clinically significant anxiety problems was nearly doubled (p
Cagnoli, Bruno; Piersanti, Antonio
2017-02-01
We have carried out new three-dimensional numerical simulations by using a discrete element method (DEM) to study the mobility of dry granular flows of angular rock fragments. These simulations are relevant for geophysical flows such as rock avalanches and pyroclastic flows. The model is validated by previous laboratory experiments. We confirm that (1) the finer the grain size, the larger the mobility of the center of mass of granular flows; (2) the smaller the flow volume, the larger the mobility of the center of mass of granular flows and (3) the wider the channel, the larger the mobility of the center of mass of granular flows. The grain size effect is due to the fact that finer grain size flows dissipate intrinsically less energy. This volume effect is the opposite of that experienced by the flow fronts. The original contribution of this paper consists of providing a comparison of the mobility of granular flows in six channels with a different cross section each. This results in a new scaling parameter χ that has the product of grain size and the cubic root of flow volume as the numerator and the product of channel width and flow length as the denominator. The linear correlation between the reciprocal of mobility and parameter χ is statistically highly significant. Parameter χ confirms that the mobility of the center of mass of granular flows is an increasing function of the ratio of the number of fragments per unit of flow mass to the total number of fragments in the flow. These are two characteristic numbers of particles whose effect on mobility is scale invariant.
Fabrics, Facies And Flow Through A Large-Volume Ignimbrite: Pampa De Oxaya, Chile.
Platzman, Ellen; Cooper, Frances
2016-04-01
Large volume pyroclastic currents form during some of the most destructive volcanic eruptions on the planet, yet because they are underrepresented in the geological record they remain poorly understood. The Miocene Oxaya ignimbrites, exposed along the western Andean slopes in northern Chile, form one of the largest ignimbrite provinces on earth. We use anisotropy of magnetic susceptibility (AMS) in conjunction with rock magnetic measurements to investigate flow behavior and depositional processes in one of the largest members of the Oxaya succession, the Cardones ignimbrite. Despite its prominence the location of the source caldera remains unknown and fundamental processes remain poorly constrained. During 2012 nearly 8km (7,773m) of core was recovered from the early Miocene ignimbrites in 11 holes at elevations ranging from 2336m to 3805m along the Andean escarpment east of Arica, Chile. The drill cores are remarkable in that they penetrate through the entirety of the ignimbrite sequence and into the basement below. Samples for this study were collected from a > 1 km long core drilled at an altitude 3692m. The core sampled 981 m of Cardones ignimbrite and 15 m of underlying sediments and volcaniclastics before penetrating 148 m of basement. Detailed measurements of the variation in bulk magnetic properties including natural remanent magnetization (NRM), susceptibility, ARM, and IRM, were used to monitor changes in concentration, composition and grainsize of the magnetic components though the ignimbrite. AMS in conjunction with detailed rock magnetic measurements were used to constrain flow processes. The data reveal a well-defined flow direction and systematic variations in flow processes with depth. Low field bulk magnetic susceptibility averages 3.2x10-3 SI. Rock magnetic studies and petrographic examination indicate that magnetite is likely to be the dominant magnetic phase although paramagnetic mineral phases also contribute to the magnetic fabric. The degree
Energy Technology Data Exchange (ETDEWEB)
Sieverding, L.; Apitz, J. (Tuebingen Univ. (Germany). Abt. fuer Paediatrische Kardiologie); Jung, W.I. (Tuebingen Univ. (Germany). Abt. fuer Paediatrische Kardiologie Tuebingen Univ. (Germany). Physikalisches Inst.); Klose, U. (Tuebingen Univ. (Germany). Medizinisches Strahleninstitut und Roentgenabteilung)
1992-04-01
Based on the phase difference method as described by Nayler et al. we developed a gradient-echo sequence, which refocuses flow related phase shifts even for infants with their higher peak velocity, higher acceleration and faster heart rates. A repetition time (TR) of 15 ms provides a high temporal resolution for dynamic studies. Modification of the flow-rephasing gradient-echo sequence in slice select direction leads to a defined phase shift and the resultant phase difference images allow blood flow measurements in the great arteries and the calculation of blood volume per heart cycle (flow volume) to assess left and right ventricular stroke volume. This can also be achieved by calculation of the ventricular volume from contiguous slices of the whole heart, but, this in excessive measuring times. Both methods were applied in 6 examinations of children with congenital heart diseases (1 pulmonary sling, 1 coarctation of the aorta, 1 ventricular septal defect, 3 atrial septal defects). The age of the patients ranged from 3 months to 13.4 years (mean age 4.9 years). The regression analyses of both methods show a high correlation for systemic flow (y=-0.98+1.08 x, r=0.99, SEE=2.59 ml) and for pulmonary flow (y=-1.40+0.96 x, r=0.99, SEE=4.70 ml). The comparison of flow calculated Qp:Qs ratio and chamber size calculated Qp:Qs ratio with data obtained by heart catheterization show also a regression line close to the line of identity (y=-0.01+1.04 x, r=0.98, SEE=0.15 and y=0.28+0.96 x, r=0.81, SEE=0.47, respectively). (orig.).
Directory of Open Access Journals (Sweden)
Chaarani Bader
2013-01-01
Full Text Available Purpose. This work suggests a fast estimation method of the lateral ventricles volume from a 2D image and then determines if this volume is correlated with the cerebrospinal fluid flow at the aqueductal and cerebral levels in neurodegenerative diseases. Materials and Methods. FForty-five elderly patients suffering from Alzheimer’s disease (19, normal pressure hydrocephalus (13, and vascular dementia (13 were involved and underwent anatomical and phase contrast MRI scans. Lateral ventricles and stroke volumes were assessed on anatomical and phase contrast scans, respectively. A common reference plane was used to calculate the lateral ventricles’ area on 2D images. Results. The largest volumes were observed in hydrocephalus patients. The linear regression between volumes and areas was computed, and a strong positive correlation was detected (R2=0.9. A derived equation was determined to represent the volumes for any given area. On the other hand, no significant correlations were detected between ventricles and stroke volumes (R2≤0.15. Conclusion. Lateral ventricles volumes are significantly proportional to the 2D reference section area and could be used for patients’ follow-up even if 3D images are unavailable. The cerebrospinal fluid fluctuations in brain disorders may depend on many physiological parameters other than the ventricular morphology.
Hybrid finite volume scheme for a two-phase flow in heterogeneous porous media*
Directory of Open Access Journals (Sweden)
Brenner Konstantin
2012-04-01
Full Text Available We propose a finite volume method on general meshes for the numerical simulation of an incompressible and immiscible two-phase flow in porous media. We consider the case that can be written as a coupled system involving a degenerate parabolic convection-diffusion equation for the saturation together with a uniformly elliptic equation for the global pressure. The numerical scheme, which is implicit in time, allows computations in the case of a heterogeneous and anisotropic permeability tensor. The convective fluxes, which are non monotone with respect to the unknown saturation and discontinuous with respect to the space variables, are discretized by means of a special Godunov scheme. We prove the existence of a discrete solution which converges, along a subsequence, to a solution of the continuous problem. We present a number of numerical results in space dimension two, which confirm the efficiency of the numerical method. Nous proposons un schéma de volumes finis hybrides pour la discrétisation d’un problème d’écoulement diphasique incompressible et immiscible en milieu poreux. On suppose que ce problème a la forme d’une équation parabolique dégénérée de convection-diffusion en saturation couplée à une équation uniformément elliptique en pression. On considère un schéma implicite en temps, où les flux diffusifs sont discrétisés par la méthode des volumes finis hybride, ce qui permet de pouvoir traiter le cas d’un tenseur de perméabilité anisotrope et hétérogène sur un maillage très général, et l’on s’appuie sur un schéma de Godunov pour la discrétisation des flux convectifs, qui peuvent être non monotones et discontinus par rapport aux variables spatiales. On démontre l’existence d’une solution discrète, dont une sous-suite converge vers une solution faible du problème continu. On présente finalement des cas test bidimensionnels.
Hybrid finite-volume/transported PDF method for the simulation of turbulent reactive flows
Raman, Venkatramanan
A novel computational scheme is formulated for simulating turbulent reactive flows in complex geometries with detailed chemical kinetics. A Probability Density Function (PDF) based method that handles the scalar transport equation is coupled with an existing Finite Volume (FV) Reynolds-Averaged Navier-Stokes (RANS) flow solver. The PDF formulation leads to closed chemical source terms and facilitates the use of detailed chemical mechanisms without approximations. The particle-based PDF scheme is modified to handle complex geometries and grid structures. Grid-independent particle evolution schemes that scale linearly with the problem size are implemented in the Monte-Carlo PDF solver. A novel algorithm, in situ adaptive tabulation (ISAT) is employed to ensure tractability of complex chemistry involving a multitude of species. Several non-reacting test cases are performed to ascertain the efficiency and accuracy of the method. Simulation results from a turbulent jet-diffusion flame case are compared against experimental data. The effect of micromixing model, turbulence model and reaction scheme on flame predictions are discussed extensively. Finally, the method is used to analyze the Dow Chlorination Reactor. Detailed kinetics involving 37 species and 158 reactions as well as a reduced form with 16 species and 21 reactions are used. The effect of inlet configuration on reactor behavior and product distribution is analyzed. Plant-scale reactors exhibit quenching phenomena that cannot be reproduced by conventional simulation methods. The FV-PDF method predicts quenching accurately and provides insight into the dynamics of the reactor near extinction. The accuracy of the fractional time-stepping technique in discussed in the context of apparent multiple-steady states observed in a non-premixed feed configuration of the chlorination reactor.
Two-dimensional finite volume method for dam-break flow simulation
Institute of Scientific and Technical Information of China (English)
M.ALIPARAST
2009-01-01
A numerical model based upon a second-order upwind cell-center finite volume method on unstructured triangular grids is developed for solving shallow water equations.The assumption of a small depth downstream instead of a dry bed situation changes the wave structure and the propagation speed of the front which leads to incorrect results.The use of Harten-Lax-vau Leer (HLL) allows handling of wet/dry treatment.By usage of the HLL approximate Riemann solver,also it make possible to handle discontinuous solutions.As the assumption of a very small depth downstream of the dam can change the nature of the dam break flow problem which leads to incorrect results,the HLL approximate Riemann solver is used for the computation of inviscid flux functions,which makes it possible to handle discontinuous solutions.A multidimensional slope-limiting technique is applied to achieve second-order spatial accuracy and to prevent spurious oscillations.To alleviate the problems associated with numerical instabilities due to small water depths near a wet/dry boundary,the friction source terms are treated in a fully implicit way.A third-order Runge-Kutta method is used for the time integration of semi-discrete equations.The developed numerical model has been applied to several test cases as well as to real flows.The tests are tested in two cases:oblique hydraulic jump and experimental dam break in converging-diverging flume.Numerical tests proved the robustness and accuracy of the model.The model has been applied for simulation of dam break analysis of Torogh in Irun.And finally the results have been used in preparing EAP (Emergency Action Plan).
Child Abuse: Its Relationship to Birthweight, Apgar Score, and Developmental Testing.
Goldson, Edward; And Others
1978-01-01
The relationship of child abuse to birthweight, five-minute Apgar score, and performance on the Bayley Scales of Infant Development was studied in 75 low socioeconomic infants (ages 2-30 months). Journal availability: see EC 111 042. (Author)
National Research Council Canada - National Science Library
Seng, JS; Low, LK; Sperlich, M; Ronis, DL; Liberzon, I
2011-01-01
...‐traumatic stress disorder (PTSD) is associated with lower birthweight and shorter gestation, and to explore the effects of childhood maltreatment as the antecedent trauma exposure. Design Prospective three‐cohort study. Setting...
Laufer, N.; Hansmann, H.; Koch, M.
2017-01-01
In this study, the rheological properties of wood plastic composites (WPC) with different polymeric matrices (LDPE, low-density polyethylene and PP, polypropylene) and with different types of wood filler (hardwood flour and softwood flour) have been investigated by means of high pressure capillary rheometry. The volume fraction of wood was varied between 0 and 60 %. The shear thinning behaviour of the WPC melts can be well described by the Ostwald - de Waele power law relationship. The flow consistency index K of the power law shows a good correlation with the volume fraction of wood. Interparticular interaction effects of wood particles can be mathematically taken into account by implementation of an interaction exponent (defined as the ratio between flow exponent of WPC and flow exponent of polymeric matrix). The interaction exponent shows a good correlation with the flow consistency index. On the basis of these relationships the concept of shear-stress-equivalent inner shear rate has been modified. Thus, the flow behaviour of the investigated wood filled polymer melts could be well described mathematically by the modified concept of shear-stress-equivalent inner shear rate. On this basis, the shear thinning behaviour of WPC can now be estimated with good accuracy, taking into account the volume fraction of wood.
Directory of Open Access Journals (Sweden)
Shin Takayama
2011-01-01
Full Text Available In traditional Chinese medicine, moxibustion is a local thermal therapy that is used for several conditions. Quantifying the effects of moxibustion therapy has been difficult because the treatment temperature depends on the physician's experience, and the temperature distribution in the target area is not uniform. This prospective observational study aims to quantify the effect of local thermal stimulation to the abdomen. We developed a heat transfer control device (HTCD for local thermal stimulation. Twenty-four healthy subjects were enrolled and they underwent abdominal thermal stimulation to the para-umbilical region with the device for 20 min. Blood flow volume in the superior mesenteric artery (SMA and brachial artery (BA, the heart rate and the blood pressure were measured at rest, 15 min after starting thermal stimulation and 10, 20, 30 and 40 min after completing thermal stimulation. Blood flow parameters were measured by high-resolution ultrasound. In the SMA, blood flow volume was significantly increased during thermal stimulation (, as well as at 10 min ( and 20 min ( after stimulation. In the BA, blood flow volume decreased at 40 min after stimulation (. In conclusion we could quantify the effect of local thermal stimulation with an HTCD and high-resolution ultrasound. Thermal stimulation of the para-umbilical region increased blood flow in the SMA 20 min after stimulation in healthy subjects.
Directory of Open Access Journals (Sweden)
Gert HOLLER
2009-08-01
Full Text Available This paper presents a capacitive and a vision-based method for measuring the velocity of cryogenic hydrogen flows. The capacitive sensing principle exploits the spatial frequency signature of perturbations moving through a multi-electrode structure. This setup increases the sensitivity to dielectric permittivity variations compared to a simple two-electrode structure while preserving the ability to detect small perturbations. The vision-based method relies on a high-speed camera system that monitors the liquid hydrogen flow through an optical window yielding the flow velocity by cross-correlating subsequent images of the flow. Although a comprehensive analysis of the obtainable measurement uncertainty was not performed yet, current measurement results show the applicability of both principles for the non-invasive measurement of the volume flow of cryogenic fuels inside conveyor pipes.
Mostaghimi, P.; Percival, J. R.; Pavlidis, D.; Gorman, G.; Jackson, M.; Neethling, S.; Pain, C. C.
2013-12-01
Numerical simulation of multiphase flow in porous media is of importance in a wide range of applications in science and engineering. We present a novel control volume finite element method (CVFEM) to solve for multi-scale flow in heterogeneous geological formations. It employs a node centred control volume approach to discretize the saturation equation, while a control volume finite element method is applied for the pressure equation. We embed the discrete continuity equation into the pressure equation and assure that the continuity is exactly enforced. Anisotropic mesh adaptivity is used to accurately model the fine grained features of multiphase flow. The adaptive algorithm uses a metric tensor field based on solution error estimates to locally control the size and shape of elements in the metric. Moreover, it uses metric advection between adaptive meshes in order to predict the future required density of mesh thereby reducing numerical dispersion at the saturation front. The scheme is capable of capturing multi-scale heterogeneity such as those in fractured porous media through the use of several constraints on the element size in different regions of porous media. We show the application of our method for simulation of flow in some challenging benchmark problems. For flow in fractured reservoirs, the scheme adapts the mesh as the flow penetrates through the fracture and the matrix. The constraints for the element size within the fracture are smaller by several orders of magnitude than the generated mesh within the matrix. We show that the scheme captures the key multi-scale features of flow while preserving the geometry. We demonstrate that mesh adaptation can be used to accurately simulate flow in heterogeneous porous media at low computational cost.
Patterning in birthweight in India: analysis of maternal recall and health card data.
Directory of Open Access Journals (Sweden)
Malavika A Subramanyam
Full Text Available BACKGROUND: National data on birthweight from birth certificates or medical records are not available in India. The third Indian National Family Health Survey included data on birthweight of children obtained from health cards and maternal recall. This study aims to describe the population that these data represent and compares the birthweight obtained from health cards with maternal recall data in terms of its socioeconomic patterning and as a risk factor for childhood growth failure. METHODOLOGY/PRINCIPAL FINDINGS: The analytic sample consisted of children aged 0 to 59 months with birthweight data obtained from health cards (n = 3227 and maternal recall (n = 16,787. The difference between the card sample and the maternal recall sample in the distribution across household wealth, parental education, caste, religion, gender, and urban residence was compared using multilevel models. We also assessed the ability of birthweight to predict growth failure in infancy and childhood in the two groups. The survey contains birthweight data from a majority of household wealth categories (>5% in every category for recall, both genders, all age groups, all caste groups, all religion groups, and urban and rural dwellers. However, children from the lowest quintile of household wealth were under-represented (4.73% in card and 8.62% in recall samples. Comparison of data across health cards and maternal recall revealed similar social patterning of low birthweight and ability of birthweight to predict growth failure later in life. Children were less likely to be born with low birthweight if they had mothers with over 12 years of education compared to 1-5 years of education with relative risk (RR of 0.79 (95% confidence interval [CI]: 0.52, 1.2 in the card sample and 0.70 (95% CI: 0.59, 0.84 in the recall sample. A 100 gram difference in a child's birthweight was associated with a decreased likelihood of underweight in both the card (RR: 0.95; 95% CI: 0.94, 0
Solution of the square lid-driven cavity flow of a Bingham plastic using the finite volume method
Syrakos, Alexandros; Alexandrou, Andreas N
2016-01-01
We investigate the performance of the finite volume method in solving viscoplastic flows. The creeping square lid-driven cavity flow of a Bingham plastic is chosen as the test case and the constitutive equation is regularised as proposed by Papanastasiou [J. Rheol. 31 (1987) 385-404]. It is shown that the convergence rate of the standard SIMPLE pressure-correction algorithm, which is used to solve the algebraic equation system that is produced by the finite volume discretisation, severely deteriorates as the Bingham number increases, with a corresponding increase in the non-linearity of the equations. It is shown that using the SIMPLE algorithm in a multigrid context dramatically improves convergence, although the multigrid convergence rates are much worse than for Newtonian flows. The numerical results obtained for Bingham numbers as high as 1000 compare favourably with reported results of other methods.
Undiagnosed coeliac disease in a father does not influence birthweight and preterm birth.
LENUS (Irish Health Repository)
Khashan, Ali S
2012-01-31
There is conflicting evidence regarding the effect of coeliac disease (CD) in the father on birthweight and preterm birth. We investigated the association between paternal CD and birthweight and preterm birth. Medical records of all singleton live-born children in Denmark between 1 January 1979 and 31 December 2004 were linked to information about parents\\' diseases. Fathers who were diagnosed with CD were then identified. Fathers with CD were considered treated if they were diagnosed before pregnancy and untreated if they were diagnosed after the date of conception. The outcome measures were: birthweight, small-for-gestational age (birthweight<10th centile for gestational age) and preterm birth (<37 weeks). We compared the offspring of men without CD (n = 1 472 352) and offspring of those with CD [untreated (n = 138) and treated (n = 473)]. There was no significant association between untreated CD in the father and birthweight (adjusted mean difference = -3 g; [95% CI -46, 40]) or preterm birth (adjusted odds ratio (OR) = 0.86, [95% CI 0.53, 1.37]) (compared with no CD). There was some evidence for an association between treated paternal CD and birthweight (adjusted mean difference = -81 g; [95% CI -161, -3]), but not preterm birth (adjusted OR = 1.76, [95% CI 0.95, 3.26]). Untreated paternal CD was not associated with an increased risk of reduced birthweight, or of preterm birth. There was some evidence that diagnosis and presumed treatment of paternal CD with a gluten-free diet is associated with reduced birthweight.
The effect of Swedish snuff (snus on offspring birthweight: a sibling analysis.
Directory of Open Access Journals (Sweden)
Sol Pía Juárez
Full Text Available Current observational evidence indicates that maternal smoking during pregnancy is associated with reduced birthweight in offspring. However, less is known about the effect of smokeless tobacco on birthweight and about the possible mechanisms involved in this relationship. This paper studies the effect of Swedish smokeless tobacco (snus on offspring birthweight comparing the results obtained from a conventional linear regression analysis and from a quasi-experimental sibling design using a multilevel linear regression analysis. From the Swedish Medical Birth Register, we investigated 604,804 singletons born between 2002 and 2010. From them, we isolated 8,861 siblings from 4,104 mothers with discrepant snus-use habits (i.e., women who had at least one pregnancy during which they used snus and at least one other pregnancy in which they did not. The conventional analysis shows that continuous snus use throughout the pregnancy reduces birthweight in 47 g while quitting or relapsing snus has a minor and statistically non-significant effect (-6 g and -4 g, respectively. However, using a sibling analysis the effect observed for mothers who continue to use snus during pregnancy is less intense than that observed with previous conventional analyses (-20 g, and this effect is not statistically significant. Sibling analysis shows that quitting or relapsing snus use after the first trimester slightly reduces birthweight (14 g. However, this small change is not statistically significant. The sibling analysis provides strong causal evidence indicating that exposure to snus during pregnancy has a minor effect on birthweight reduction. Our findings provide a new piece of causal evidence concerning the effect of tobacco on birthweight and support the hypothesis that the harmful effect of smoking on birthweight is not mainly due to nicotine.
Verdin, Kristine L.; Dupree, Jean A.; Elliott, John G.
2012-01-01
This report presents a preliminary emergency assessment of the debris-flow hazards from drainage basins burned by the 2012 Waldo Canyon fire near Colorado Springs in El Paso County, Colorado. Empirical models derived from statistical evaluation of data collected from recently burned basins throughout the intermountain western United States were used to estimate the probability of debris-flow occurrence and potential volume of debris flows along the drainage network of the burned area and to estimate the same for 22 selected drainage basins along U.S. Highway 24 and the perimeter of the burned area. Input data for the models included topographic parameters, soil characteristics, burn severity, and rainfall totals and intensities for a (1) 2-year-recurrence, 1-hour-duration rainfall, referred to as a 2-year storm (29 millimeters); (2) 10-year-recurrence, 1-hour-duration rainfall, referred to as a 10-year storm (42 millimeters); and (3) 25-year-recurrence, 1-hour-duration rainfall, referred to as a 25-year storm (48 millimeters). Estimated debris-flow probabilities at the pour points of the the drainage basins of interest ranged from less than 1 to 54 percent in response to the 2-year storm; from less than 1 to 74 percent in response to the 10-year storm; and from less than 1 to 82 percent in response to the 25-year storm. Basins and drainage networks with the highest probabilities tended to be those on the southern and southeastern edge of the burn area where soils have relatively high clay contents and gradients are steep. Nine of the 22 drainage basins of interest have greater than a 40-percent probability of producing a debris flow in response to the 10-year storm. Estimated debris-flow volumes for all rainfalls modeled range from a low of 1,500 cubic meters to a high of greater than 100,000 cubic meters. Estimated debris-flow volumes increase with basin size and distance along the drainage network, but some smaller drainages were also predicted to produce
Variable thickness transient ground-water flow model. Volume 3. Program listings
Energy Technology Data Exchange (ETDEWEB)
Reisenauer, A.E.
1979-12-01
The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (OWNI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologic systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. Hydrologic and transport models are available at several levels of complexity or sophistication. Model selection and use are determined by the quantity and quality of input data. Model development under AEGIS and related programs provides three levels of hydrologic models, two levels of transport models, and one level of dose models (with several separate models). This is the third of 3 volumes of the description of the VTT (Variable Thickness Transient) Groundwater Hydrologic Model - second level (intermediate complexity) two-dimensional saturated groundwater flow.
3D flow study in a mildly stenotic coronary artery phantom using a whole volume PIV method.
Brunette, J; Mongrain, R; Laurier, J; Galaz, R; Tardif, J C
2008-11-01
Blood flow dynamics has an important role in atherosclerosis initiation, progression, plaque rupture and thrombosis eventually causing myocardial infarction. In particular, shear stress is involved in platelet activation, endothelium function and secondary flows have been proposed as possible variables in plaque erosion. In order to investigate these three-dimensional flow characteristics in the context of a mild stenotic coronary artery, a whole volume PIV method has been developed and applied to a scaled-up transparent phantom. Experimental three-dimensional velocity data was processed to estimate the 3D shear stress distributions and secondary flows within the flow volume. The results show that shear stress reaches values out of the normal and atheroprotective range at an early stage of the obstructive pathology and that important secondary flows are also initiated at an early stage of the disease. The results also support the concept of a vena contracta associated with the jet in the context of a coronary artery stenosis with the consequence of higher shear stresses in the post-stenotic region in the blood domain than at the vascular wall.
Institute of Scientific and Technical Information of China (English)
Zailin GUAN; Yunfang PENG; Li MA; Chaoyong ZHANG; Peigen LI
2008-01-01
The existing technology of flow manufacturing, which is mainly appropriate for high volume and repetitive production, is proven difficult to be applied in high-mix/ low-volume environments. To adapt lean production into the latter, a new type of flow manufacturing is proposed based on flow path management technology. This paper first describes the general operation framework of the pro-posed new mode. The main idea is the dynamic formation of adaptable virtual production lines (called flow paths) corresponding to different product families. The applica-tion of different theories of constraints/drum-buffer-rope (TOC/DBR) control policies depends on the differences in scope of variety and scale of demand for these product families. The overall architecture of the proposed mech-anism of constraint management-based operation and con-trol is introduced. For the implementation, a mathematical programming method is suggested for the dynamic plan-ning of flow paths, and a TOC/DBR 'path-specific' mech-anism with group scheduling is used for the control over each flow path. We also study other critical issues including the identification and management of resource bottlenecks, and the setting of the buffer size in the deployment of the TOC/DBR mechanism.
Verdin, Kristine L.; Dupree, Jean A.; Elliott, John G.
2012-01-01
This report presents a preliminary emergency assessment of the debris-flow hazards from drainage basins burned by the 2012 High Park fire near Fort Collins in Larimer County, Colorado. Empirical models derived from statistical evaluation of data collected from recently burned basins throughout the intermountain western United States were used to estimate the probability of debris-flow occurrence and volume of debris flows along the burned area drainage network and to estimate the same for 44 selected drainage basins along State Highway 14 and the perimeter of the burned area. Input data for the models included topographic parameters, soil characteristics, burn severity, and rainfall totals and intensities for a (1) 2-year-recurrence, 1-hour-duration rainfall (25 millimeters); (2) 10-year-recurrence, 1-hour-duration rainfall (43 millimeters); and (3) 25-year-recurrence, 1-hour-duration rainfall (51 millimeters). Estimated debris-flow probabilities along the drainage network and throughout the drainage basins of interest ranged from 1 to 84 percent in response to the 2-year-recurrence, 1-hour-duration rainfall; from 2 to 95 percent in response to the 10-year-recurrence, 1-hour-duration rainfall; and from 3 to 97 in response to the 25-year-recurrence, 1-hour-duration rainfall. Basins and drainage networks with the highest probabilities tended to be those on the eastern edge of the burn area where soils have relatively high clay contents and gradients are steep. Estimated debris-flow volumes range from a low of 1,600 cubic meters to a high of greater than 100,000 cubic meters. Estimated debris-flow volumes increase with basin size and distance along the drainage network, but some smaller drainages were also predicted to produce substantial volumes of material. The predicted probabilities and some of the volumes predicted for the modeled storms indicate a potential for substantial debris-flow impacts on structures, roads, bridges, and culverts located both within and
Verkaik, A. C.; Beulen, B. W. A. M. M.; Bogaerds, A. C. B.; Rutten, M. C. M.; van de Vosse, F. N.
2009-02-01
To monitor biomechanical parameters related to cardiovascular disease, it is necessary to perform correct volume flow estimations of blood flow in arteries based on local blood velocity measurements. In clinical practice, estimates of flow are currently made using a straight-tube assumption, which may lead to inaccuracies since most arteries are curved. Therefore, this study will focus on the effect of curvature on the axial velocity profile for flow in a curved tube in order to find a new volume flow estimation method. The study is restricted to steady flow, enabling the use of analytical methods. First, analytical approximation methods for steady flow in curved tubes at low Dean numbers (Dn) and low curvature ratios (δ) are investigated. From the results a novel volume flow estimation method, the cos θ-method, is derived. Simulations for curved tube flow in the physiological range (1≤Dn≤1000 and 0.01≤δ≤0.16) are performed with a computational fluid dynamics (CFD) model. The asymmetric axial velocity profiles of the analytical approximation methods are compared with the velocity profiles of the CFD model. Next, the cos θ-method is validated and compared with the currently used Poiseuille method by using the CFD results as input. Comparison of the axial velocity profiles of the CFD model with the approximations derived by Topakoglu [J. Math. Mech. 16, 1321 (1967)] and Siggers and Waters [Phys. Fluids 17, 077102 (2005)] shows that the derived velocity profiles agree very well for Dn≤50 and are fair for 50100), no analytical approximation method exists. In the position of the maximum axial velocity, a shift toward the inside of the curve is observed for low Dean numbers, while for high Dean numbers, the position of the maximum velocity is located at the outer curve. When the position of the maximum velocity of the axial velocity profile is given as a function of the Reynolds number, a "zero-shift point" is found at Re=21.3. At this point the shift in
Energy Technology Data Exchange (ETDEWEB)
Espinosa-Paredes, Gilberto, E-mail: gepe@xanum.uam.m [Area de Ingenieria en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, Apartado Postal 55-535, Mexico D.F. 09340 (Mexico)
2010-05-15
The aim of this paper is to propose a framework to obtain a new formulation for multiphase flow conservation equations without length-scale restrictions, based on the non-local form of the averaged volume conservation equations. The simplification of the local averaging volume of the conservation equations to obtain practical equations is subject to the following length-scale restrictions: d << l << L, where d is the characteristic length of the dispersed phases, l is the characteristic length of the averaging volume, and L is the characteristic length of the physical system. If the foregoing inequality does not hold, or if the scale of the problem of interest is of the order of l, the averaging technique and therefore, the macroscopic theories of multiphase flow should be modified in order to include appropriate considerations and terms in the corresponding equations. In these cases the local form of the averaged volume conservation equations are not appropriate to describe the multiphase system. As an example of the conservation equations without length-scale restrictions, the natural circulation boiling water reactor was consider to study the non-local effects on the thermal-hydraulic core performance during steady-state and transient behaviors, and the results were compared with the classic local averaging volume conservation equations.
Comparison of two flow-based imaging methods to measure individual red blood cell area and volume.
Tomaiuolo, Giovanna; Rossi, Domenico; Caserta, Sergio; Cesarelli, Mario; Guido, Stefano
2012-12-01
The red blood cells (RBCs) population is characterized by a high heterogeneity in membrane area, cellular volume, and mechanical properties, mainly due to the variety of mechanical and chemical stresses that a red cell undergoes in its entire life span. Here, we provide the first simultaneous area and volume measurements of RBCs flowing in microcapillaries, by using high-speed video microscopy imaging and quantitative data processing based on image analysis techniques. Both confined and unbounded flow conditions (depending on the relative size of RBCs and microcapillary diameter) are investigated. The results are compared with micropipette experiments from the literature and data from Coulter counter routine clinical blood tests. Good agreement is found for RBC volume, especially in the case of confined flow conditions. Surface area measurements, which are lacking in the routine clinical test, are of special interest being a potential diagnostic parameter of altered cell deformability and aggregability. Overall, our results provide a novel flow methodology suitable for high-throughput measurements of RBC geometrical parameters, allowing one to overcome the limits of classical static methods, such as micropipette aspiration, which are not suitable for handling a large number of cells.
Directory of Open Access Journals (Sweden)
Florian G. Strobl
2015-02-01
Full Text Available Static conditions represent an important shortcoming of many in vitro experiments on the cellular uptake of nanoparticles. Here, we present a versatile microfluidic device based on acoustic streaming induced by surface acoustic waves (SAWs. The device offers a convenient method for introducing fluid motion in standard cell culture chambers and for mimicking capillary blood flow. We show that shear rates over the whole physiological range in sample volumes as small as 200 μL can be achieved. A precise characterization method for the induced flow profile is presented and the influence of flow on the uptake of Pt-decorated CeO2 particles by endothelial cells (HMEC-1 is demonstrated. Under physiological flow conditions the particle uptake rates for this system are significantly lower than at low shear conditions. This underlines the vital importance of the fluidic environment for cellular uptake mechanisms.
Institute of Scientific and Technical Information of China (English)
V.MEDINA; A.BATEMAN; M.H(U)RLIMANN
2008-01-01
FLATModel is a 2D finite volume code that contains several original approaches to improve debris-flow simulation.Firstly,FLATModel incorporates a "stop-and-go" technique in each cell to allow continuous collapses and remobilizations of the debris-flow mass.Secondly,flow velocity and consequently yield stress is directly associated with the type of rheology to improve boundary accuracy.Thirdly,a simple approach for entrainment is also included in the model to analyse the effect of basal erosion of debris flows.FLATMODEL was tested at several events that occurred in the Eastern Pyrenees and simulation results indicated that the model can represent rather well the different characteristics observed in the field.
Schafhitzel, Tobias; Rößler, Friedemann; Weiskopf, Daniel; Ertl, Thomas
2007-03-01
Modern medical imaging provides a variety of techniques for the acquisition of multi-modality data. A typical example is the combination of functional and anatomical data from functional Magnetic Resonance Imaging (fMRI) and anatomical MRI measurements. Usually, the data resulting from each of these two methods is transformed to 3D scalar-field representations to facilitate visualization. A common method for the visualization of anatomical/functional multi-modalities combines semi-transparent isosurfaces (SSD, surface shaded display) with other scalar visualization techniques like direct volume rendering (DVR). However, partial occlusion and visual clutter that typically result from the overlay of these traditional 3D scalar-field visualization techniques make it difficult for the user to perceive and recognize visual structures. This paper addresses these perceptual issues by a new visualization approach for anatomical/functional multi-modalities. The idea is to reduce the occlusion effects of an isosurface by replacing its surface representation by a sparser line representation. Those lines are chosen along the principal curvature directions of the isosurface and rendered by a flow visualization method called line integral convolution (LIC). Applying the LIC algorithm results in fine line structures that improve the perception of the isosurface's shape in a way that it is possible to render it with small opacity values. An interactive visualization is achieved by executing the algorithm completely on the graphics processing unit (GPU) of modern graphics hardware. Furthermore, several illumination techniques and image compositing strategies are discussed for emphasizing the isosurface structure. We demonstrate our method for the example of fMRI/MRI measurements, visualizing the spatial relationship between brain activation and brain tissue.
Evaluation of two-phase flow solvers using Level Set and Volume of Fluid methods
Bilger, C.; Aboukhedr, M.; Vogiatzaki, K.; Cant, R. S.
2017-09-01
Two principal methods have been used to simulate the evolution of two-phase immiscible flows of liquid and gas separated by an interface. These are the Level-Set (LS) method and the Volume of Fluid (VoF) method. Both methods attempt to represent the very sharp interface between the phases and to deal with the large jumps in physical properties associated with it. Both methods have their own strengths and weaknesses. For example, the VoF method is known to be prone to excessive numerical diffusion, while the basic LS method has some difficulty in conserving mass. Major progress has been made in remedying these deficiencies, and both methods have now reached a high level of physical accuracy. Nevertheless, there remains an issue, in that each of these methods has been developed by different research groups, using different codes and most importantly the implementations have been fine tuned to tackle different applications. Thus, it remains unclear what are the remaining advantages and drawbacks of each method relative to the other, and what might be the optimal way to unify them. In this paper, we address this gap by performing a direct comparison of two current state-of-the-art variations of these methods (LS: RCLSFoam and VoF: interPore) and implemented in the same code (OpenFoam). We subject both methods to a pair of benchmark test cases while using the same numerical meshes to examine a) the accuracy of curvature representation, b) the effect of tuning parameters, c) the ability to minimise spurious velocities and d) the ability to tackle fluids with very different densities. For each method, one of the test cases is chosen to be fairly benign while the other test case is expected to present a greater challenge. The results indicate that both methods can be made to work well on both test cases, while displaying different sensitivity to the relevant parameters.
Directory of Open Access Journals (Sweden)
Pisi R
2015-06-01
Full Text Available Roberta Pisi,1 Marina Aiello,1 Andrea Zanini,2 Panagiota Tzani,1 Davide Paleari,3 Emilio Marangio,1 Antonio Spanevello,2,4 Gabriele Nicolini,5 Alfredo Chetta1 1Department of Clinical and Experimental Medicine, University of Parma, Parma, 2Division of Pneumology, IRCCS Rehabilitation Institute of Tradate, Salvatore Maugeri Foundation, Tradate, 3Medical Department, Chiesi Farmaceutici SpA, Parma, 4Department of Clinical and Experimental Medicine, University of Insubria, Varese, 5Corporate Clinical Development, Chiesi Farmaceutici SpA, Parma, Italy Background: We investigated whether a relationship between small airways dysfunction and bronchodilator responsiveness exists in patients with chronic obstructive pulmonary disease (COPD.Methods: We studied 100 (20 female; mean age: 68±10 years patients with COPD (forced expiratory volume in 1 second [FEV1]: 55% pred ±21%; FEV1/forced vital capacity [FVC]: 53%±10% by impulse oscillometry system. Resistance at 5 Hz and 20 Hz (R5 and R20, in kPa·s·L-1 and the fall in resistance from 5 Hz to 20 Hz (R5 – R20 were used as indices of total, proximal, and peripheral airway resistance; reactance at 5 Hz (X5, in kPa·s·L-1 was also measured. Significant response to bronchodilator (salbutamol 400 µg was expressed as absolute (≥0.2 L and percentage (≥12% change relative to the prebronchodilator value of FEV1 (flow responders, FRs and FVC (volume responders, VRs.Results: Eighty out of 100 participants had R5 – R20 >0.03 kPa·s·L-1 (> upper normal limit and, compared to patients with R5 – R20 ≤0.030 kPa·s·L-1, showed a poorer health status, lower values of FEV1, FVC, FEV1/FVC, and X5, along with higher values of residual volume/total lung capacity and R5 (P<0.05 for all comparisons. Compared to the 69 nonresponders and the 8 FRs, the 16 VRs had significantly higher R5 and R5 – R20 values (P<0.05, lower X5 values (P<0.05, and greater airflow obstruction and lung
Outcomes of extremely low birthweight infants with acidosis at birth.
Randolph, David A; Nolen, Tracy L; Ambalavanan, Namasivayam; Carlo, Waldemar A; Peralta-Carcelen, Myriam; Das, Abhik; Bell, Edward F; Davis, Alexis S; Laptook, Abbot R; Stoll, Barbara J; Shankaran, Seetha; Higgins, Rosemary D
2014-07-01
To test the hypothesis that acidosis at birth is associated with the combined primary outcome of death or neurodevelopmental impairment (NDI) in extremely low birthweight (ELBW) infants, and to develop a predictive model of death/NDI exploring perinatal acidosis as a predictor variable. The study population consisted of ELBW infants born between 2002 and 2007 at National Institute of Child Health and Development (NICHD) Neonatal Research Network hospitals. Infants with cord blood gas data and documentation of either mortality prior to discharge or 18-22 month neurodevelopmental outcomes were included. Multiple logistic regression analysis was used to determine the contribution of perinatal acidosis, defined as a cord blood gas with a pHacidosis is significantly associated with death/NDI in ELBW infants. Perinatal acidosis is infrequent in ELBW infants, however, and other factors are more important in predicting death/NDI. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Growth and development in children born very low birthweight.
Scharf, Rebecca J; Stroustrup, Annemarie; Conaway, Mark R; DeBoer, Mark D
2016-09-01
To examine the relationships between growth (birth to age 2 years) and developmental outcomes in children born with very low birthweight (VLBW). Motor and mental development in children born with VLBW were regressed on anthropometric measurements at birth, 9 months and 2 years using multivariable regression. The Early Childhood Longitudinal Study-Birth Cohort, a longitudinal cohort, community sample, designed to be representative of children born across the USA. 950 children born with VLBW (children exhibited poor growth, with length-for-age z-scores children at 9 months (adjusted for prematurity) and 34.2% of children at 2 years. Compared with children having z-scores >-2, children with growth shortfalls in head circumference, length and weight had a higher adjusted OR (aOR) of low Bayley motor scores at 9 months and 2 years (aOR ranging from 1.8 to 3.3, all pchildren born with VLBW. While careful length measures may be a particularly useful marker, deficits in all anthropometric measures were risk factors for developmental delays. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
2014-01-01
Background Information tracking changes of birthweight is scarce in China. To examine trends of low birthweight (birthweight birthweight ≥ 4000 g) and potential risk factors in Beijing, hospital records from two major obstetrics and gynecology hospitals in urban districts in Beijing were analyzed. Methods Hospital records from 1996 to 2010 were retrieved. Information of prenatal examination and birth outcomes was entered into a structured database. Live births were used for trend analysis. Information of live births in 2010 was used to identify potential risk factors. Results A total of 63 661 live births were delivered during 1996–2010 in the study hospitals. The average birthweight increased from 3271 g in 1996 to 3 359 g in 2000 and slightly declined to 3 331 in 2010. The percentage of low birthweight fluctuated around 4.0%. No significant increase or decrease was observed. Preterm birth was the main cause of low birthweight, accounting for more than 73% of low birthweight. The average percentage of macrosomia was 7.6%. The percentages of macrosomia increased from 6.6% in 1996 to 9.5% in 2000 and declined to 7.0% in 2010. Excessive gestational weight gain and gestational diabetes were significantly associated with macrosomia. Conclusions Continuously monitoring abnormal birthweight is needed and intervention should focus on appropriate gestational weight gain and reduction of preterm birth and gestational diabetes. PMID:24641671
Shan, Xiaoyi; Chen, Fangfang; Wang, Wenpeng; Zhao, Juan; Teng, Yue; Wu, Minghui; Teng, Honghong; Zhang, Xue; Qi, Hong; Liu, Xiaohong; Tan, Chunying; Mi, Jie
2014-03-18
Information tracking changes of birthweight is scarce in China. To examine trends of low birthweight (birthweight macrosomia (birthweight ≥ 4000 g) and potential risk factors in Beijing, hospital records from two major obstetrics and gynecology hospitals in urban districts in Beijing were analyzed. Hospital records from 1996 to 2010 were retrieved. Information of prenatal examination and birth outcomes was entered into a structured database. Live births were used for trend analysis. Information of live births in 2010 was used to identify potential risk factors. A total of 63 661 live births were delivered during 1996-2010 in the study hospitals. The average birthweight increased from 3271 g in 1996 to 3 359 g in 2000 and slightly declined to 3 331 in 2010. The percentage of low birthweight fluctuated around 4.0%. No significant increase or decrease was observed. Preterm birth was the main cause of low birthweight, accounting for more than 73% of low birthweight. The average percentage of macrosomia was 7.6%. The percentages of macrosomia increased from 6.6% in 1996 to 9.5% in 2000 and declined to 7.0% in 2010. Excessive gestational weight gain and gestational diabetes were significantly associated with macrosomia. Continuously monitoring abnormal birthweight is needed and intervention should focus on appropriate gestational weight gain and reduction of preterm birth and gestational diabetes.
The factors affecting morbidity and mortality in low birth-weight infants
Directory of Open Access Journals (Sweden)
Mervan Bekdaş
2013-01-01
Full Text Available jective: To investigate the frequency of short term morbidity and mortality and the factors affecting them for the infants born with low birth-weight at our hospitalMethods: At our hospital, 195 infants born with low birthweight within a period of 18 months were identified and 150 infants born with normal birth-weights were selected as the control group. Results: Within the mentioned period of time, 4.4% (n=168 of the infants born in our hospital had low birthweight, 0.7% (n=27 had very low birth-weight (VLBW. Multiple pregnancies and asphyxiating birth rates were significantly high in these infants as compared to the control group. (p=0.029, p=0.011, respectively. For VLBW infants, the rates of asphyxiating birth (OR=14.2, 95% CI (6.6-30.7, p<0.001, hospitalization at the neonatal intensive care unit (OR=34.8, 95% CI (4.7-256.3, p<0,001 and diagnosis of respiratory distress syndrome (OR=11.5, 95% CI (4-33.5, p<0.001 were significantly high. In all infants, the transient metabolic disorders were identified at a significantly high rate (p=0.045. The birth-weight and gestational age of infants were inversely correlated with their fetal and neonatal mortalities (for all p<0.001. Conclusion: This study demonstrated that the most important factor affecting infants was multiple pregnancies. The birth-weight and gestational age of infants were inversely correlated with their morbidity and mortality rates.Key words: Low birth weight, perinatal risk factors, morbidity, mortality
A Review of the Impact of Dietary Intakes in Human Pregnancy on Infant Birthweight
Directory of Open Access Journals (Sweden)
Jessica A. Grieger
2014-12-01
Full Text Available Studies assessing maternal dietary intakes and the relationship with birthweight are inconsistent, thus attempting to draw inferences on the role of maternal nutrition in determining the fetal growth trajectory is difficult. The aim of this review is to provide updated evidence from epidemiological and randomized controlled trials on the impact of dietary and supplemental intakes of omega-3 long-chain polyunsaturated fatty acids, zinc, folate, iron, calcium, and vitamin D, as well as dietary patterns, on infant birthweight. A comprehensive review of the literature was undertaken via the electronic databases Pubmed, Cochrane Library, and Medline. Included articles were those published in English, in scholarly journals, and which provided information about diet and nutrition during pregnancy and infant birthweight. There is insufficient evidence for omega-3 fatty acid supplements’ ability to reduce risk of low birthweight (LBW, and more robust evidence from studies supplementing with zinc, calcium, and/or vitamin D needs to be established. Iron supplementation appears to increase birthweight, particularly when there are increases in maternal hemoglobin concentrations in the third trimester. There is limited evidence supporting the use of folic acid supplements to reduce the risk for LBW; however, supplementation may increase birthweight by ~130 g. Consumption of whole foods such as fruit, vegetables, low-fat dairy, and lean meats throughout pregnancy appears beneficial for appropriate birthweight. Intervention studies with an understanding of optimal dietary patterns may provide promising results for both maternal and perinatal health. Outcomes from these studies will help determine what sort of dietary advice could be promoted to women during pregnancy in order to promote the best health for themselves and their baby.
40 CFR Appendix III to Part 86 - Constant Volume Sampler Flow Calibration
2010-07-01
... monoxide is poisonous!). Critical flow orifice devices can also be used for constant flow metering. 2... fittings on the intake side of sample transfer pumps on both the CVS and analyzer console....
Variant of a volume-of-fluid method for surface tension-dominant two-phase flows
Indian Academy of Sciences (India)
G Biswas
2013-12-01
The capabilities of the volume-of-fluid method for the calculation of surface tension-dominant two-phase flows are explained. The accurate calculation of the interface remains a problem for the volume-of-fluid method if the density ratios of the fluids in different phases are high. The simulations of bubble growth is performed in water at near critical pressure for different degrees of superheat using combined levelset and volume-of fluid (CLSVOF) method. The effect of superheat on the frequency of bubble formation was analyzed. A deviation from the periodic bubble release is observed in the case of superheat of 20 K in water. The vapor-jet-like columnar structure is observed. Effect of heat flux on the slender vapor column has also been explained.
Cenic, A; Craen, R A; Howard-Lech, V L; Lee, T Y; Gelb, A W
2000-06-01
There are little data on the effects of propofol on cerebral blood volume (CBV). We studied the effects of changes in PaCO(2) on CBV and cerebral blood flow (CBF) during propofol anesthesia in eight New Zealand white rabbits. We also investigated the effects of propofol over time on CBV and CBF during normocapnia (control group). At normocapnia, the mean (+/- SD) CBV and CBF values were 2.41 +/- 0.68 mL/100 g and 56 +/- 28 mL/100 g/min, respectively,. When PaCO(2) was reduced from 41 to 27 mm Hg, no significant change in either CBV or CBF was observed (P > 0.10). However, increasing PaCO(2) from 41 to 58 mm Hg resulted in a 30% increase in CBV (3.08 +/- 0.86 mL/100 g, P 0.10) during 2 h of propofol anesthesia. These results indicate that, during propofol anesthesia, cerebrovascular reactivity of blood flow and blood volume is maintained during hypercapnia but is markedly diminished during hypocapnia. During propofol anesthesia in rabbits with normal brains, a reduction in the arterial carbon dioxide level may not always be accompanied by a reduction in brain blood flow and blood volume.
Institute of Scientific and Technical Information of China (English)
Wei Gao; Ru-Xun Liu; Hong Li
2012-01-01
This paper proposes a hybrid vertex-centered finite volume/finite element method for sol ution of the two dimensional (2D) incompressible Navier-Stokes equations on unstructured grids.An incremental pressure fractional step method is adopted to handle the velocity-pressure coupling.The velocity and the pressure are collocated at the node of the vertex-centered control volume which is formed by joining the centroid of cells sharing the common vertex.For the temporal integration of the momentum equations,an implicit second-order scheme is utilized to enhance the computational stability and eliminate the time step limit due to the diffusion term.The momentum equations are discretized by the vertex-centered finite volume method (FVM) and the pressure Poisson equation is solved by the Galerkin finite element method (FEM).The momentum interpolation is used to damp out the spurious pressure wiggles.The test case with analytical solutions demonstrates second-order accuracy of the current hybrid scheme in time and space for both velocity and pressure.The classic test cases,the lid-driven cavity flow,the skew cavity flow and the backward-facing step flow,show that numerical results are in good agreement with the published benchmark solutions.
Borges, Sivanildo S.; Vieira, Gláucia P.; Reis, Boaventura F.
2007-01-01
In this work, an automatic device to deliver titrant solution into a titration chamber with the ability to determine the dispensed volume of solution, with good precision independent of both elapsed time and flow rate, is proposed. A glass tube maintained at the vertical position was employed as a container for the titrant solution. Electronic devices were coupled to the glass tube in order to control its filling with titrant solution, as well as the stepwise solution delivering into the titration chamber. The detection of the titration end point was performed employing a photometer designed using a green LED (λ=545 nm) and a phototransistor. The titration flow system comprised three-way solenoid valves, which were assembled to allow that the steps comprising the solution container loading and the titration run were carried out automatically. The device for the solution volume determination was designed employing an infrared LED (λ=930 nm) and a photodiode. When solution volume delivered from proposed device was within the range of 5 to 105 μl, a linear relationship (R = 0.999) between the delivered volumes and the generated potential difference was achieved. The usefulness of the proposed device was proved performing photometric titration of hydrochloric acid solution with a standardized sodium hydroxide solution and using phenolphthalein as an external indicator. The achieved results presented relative standard deviation of 1.5%. PMID:18317510
Moser, Kath; Stanfield, Kristina M; Leon, David A
2008-01-01
Low birthweight babies and babies born preterm are at increased risk of morbidity and mortality in the first year of life, as well as in the longer-term. Since information on ethnic group is not recorded at birth registration in England and Wales, it has not been possible to produce routine statistics on birthweight or gestational age by ethnic group. A new system, introduced in 2002, for allocating NHS numbers at birth (NN4B) provided the opportunity to obtain ethnic group information. The NN4B record includes information on the ethnic group of the baby classified according to the 2001 Census categories. This paper presents the first analyses of ethnic differences in birthweight and gestational age at birth for England and Wales as a whole. Utilising NN4B records linked with birth registration records for all births occurring in England and Wales in 2005, birthweight and gestational age distributions, including the percentages low birthweight and preterm, are compared between ethnic groups. The paper also examines how parental socio-demographic circumstances vary by ethnic group.
Energy Technology Data Exchange (ETDEWEB)
Taylor, P.R.; Stelma, J.; Lawrence, C.E.
1984-09-20
A study was made of the relation between occupational exposure of women to high homolog polychlorinated biphenyls (PCB) and birthweight and gestational age among the live offspring of these workers. In 1982 interviews were conducted with 200 women who had held jobs with direct PCB exposure. A comparison was made with 205 women who had never held such a job. When all births occurring to mothers following exposure to PCBs were considered, the unadjusted mean birthweight in the direct exposure group was 96 grams less than the comparison group. No differences in gestational age were seen between groups. The birthweight difference was reduced to 41 grams following adjustment for potential confounding factors. In a parallel analysis using a continuous exposure variable estimate generated from an independently derived serum PCB prediction model, no effect of PCBs was noted on birthweight or gestational age using either crude or adjusted analyses. The authors conclude that no evidence for a biologically meaningful effect of high homolog PCBs on gestational age or birthweight exists.
Trace elements and antioxidant enzymes in extremely low birthweight infants.
Loui, Andrea; Raab, Andrea; Maier, Rolf F; Brätter, Peter; Obladen, Michael
2010-04-01
Oxygen radicals are believed to contribute to typical diseases of prematurity, such as bronchopulmonary dysplasia (BPD), intraventricular haemorrhage (IVH), retinopathy of prematurity (ROP) and necrotising enterocolitis (NEC). Our aim was to investigate whether these disorders are associated with disturbances in antioxidant enzyme activities and with low trace elements, which are co-factors of antioxidant enzymes. 209 infants with birthweight less than 1000g were enrolled into a European multicentre randomised erythropoietin (rhEPO) trial; 155 developed one or more of the above mentioned diseases. We analysed Zn, Cu, Fe, Se in plasma and red blood cells (RBCs), superoxide dismutase (CuZn-SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in RBCs on the 3rd and 68th day of life. Zn, Fe, Se in plasma, and Se in RBCs decreased (p<0.01), and Zn in RBC (p<0.001), CuZn-SOD (p<0.01) and CAT increased (p<0.05), whereas GSH-Px remained unchanged. No differences were observed between the rhEPO and control groups. Antioxidant enzyme activities did not correlate with gestational age. In infants with BPD, IVH, ROP, or NEC, CuZn-SOD and CAT (p<0.05) were higher at day 68 than in infants without these diseases. CuZn-SOD and GSH-Px at 3 days and CuZn-SOD at 68 days correlated positively (p<0.05) with the duration of oxygen treatment. In conclusion, in ELBW infants, trace element concentrations decreased over the first 10 weeks of life. Lower trace element concentrations, did not affect the activities of CuZn-SOD, GSH-Px, and CAT. Typical diseases of prematurity were not associated with decreased antioxidant enzyme activities.
Waste-aware fluid volume assignment for flow-based microfluidic biochips
DEFF Research Database (Denmark)
Schneider, Alexander Rüdiger; Pop, Paul; Madsen, Jan
2017-01-01
the fluid volume assignment for each operation of the application, such that the FUs volume requirements are satisfied, while over- and underflow are avoided and the total volume of fluid used is minimized. We propose an algorithm for this fluid assignment problem. Compared to previous work, our method...... is able to minimize the fluid consumption through optimal fluid assignment and reuse of fluid waste. Due to the algorithm's low complexity, fluid requirements can also be calculated during runtime for error recovery or statically unknown cases....
Reduced infant birthweight consequent upon maternal exposure to severe life events
DEFF Research Database (Denmark)
Khashan, Ali; McNamee, R.; Pedersen, Marianne Giørtz
2008-01-01
conception or during pregnancy have babies with significantly lower birthweight. If this association is causal, the potential mechanisms of stress-related effects on birthweight include changes in lifestyle due to the exposure and stress-related dysregulation of the hypothalamic-pituitary-adrenal axis during......OBJECTIVE: To investigate the association between maternal exposure to severe life events and fetal growth (birthweight and small for gestational age). Stress has been associated with adverse pregnancy outcome. METHODS: Mothers of 1.38 million singleton live births in Denmark between January 1......, 1979 and December 31, 2002 were linked to information on their spouses, parents, siblings, and older children. Exposure was defined as death or serious illness in a relative during pregnancy or in the 6 months before conception. Linear regression was used to examine the effect of exposure...
Type 2 diabetes risk alleles near ADCY5, CDKAL1 and HHEX-IDE are associated with reduced birthweight
DEFF Research Database (Denmark)
Andersson, E A; Pilgaard, K; Pisinger, C
2010-01-01
The fetal insulin hypothesis suggests that variation in the fetal genotype influencing insulin secretion or action may predispose to low birthweight and type 2 diabetes. We examined associations between 25 confirmed type 2 diabetes risk variants and birthweight in individuals from the Danish Inter...
DEFF Research Database (Denmark)
Olsen, S.F.; Hansen, Harald S.; Sørensen, T.I.
1986-01-01
Birthweights in the Faroe Islands are among the highest in the world. Compared with Denmark, the average birthweight of liveborn singleton infants of primiparous mothers in 194 g higher, and a substantial part of this difference seems to be attributable to longer gestation. Prostaglandins play...
Pelinck, M. J.; Hadders-Algra, M.; Haadsma, M. L.; Nijhuis, W. L.; Kiewiet, S. M.; Hoek, A.; Heineman, M. J.; Middleburg, K. J.
2010-01-01
Singletons born after IVF are at risk of adverse pregnancy outcome, the cause of which is unknown. The present study investigated the influence of ovarian stimulation and IVF laboratory procedure on birthweight. Birthweight of singleton pregnancies resulting from IVF treatment with (n = 161) and wit
DEFF Research Database (Denmark)
Wodskou, Pernille M; Hundrup, Yrsa A; Obel, Erik B;
2010-01-01
To investigate the validity of self-reported birthweight among middle-aged and elderly women and to identify possible determinants of reporting accuracy.......To investigate the validity of self-reported birthweight among middle-aged and elderly women and to identify possible determinants of reporting accuracy....
Lira, Pedro I. C.; Eickmann, Sophie H.; Lima, Marilia C.; Amorim, Rosemary J.; Emond, Alan M.; Ashworth, Ann
2010-01-01
Aim: To investigate the relation between head growth at different periods and IQ at 8 years, and to identify factors associated with more rapid head growth. Method: Two parallel cohorts of term low birthweight (LBW) and appropriate birthweight (ABW) infants were enrolled at birth in northeast Brazil. Anthropometric measurements were made at birth,…
A σ-coordinate model for 3D free-surface flows using an unstructured finite-volume technique
Uh Zapata, Miguel
2016-11-01
The aim of this work is to develop a numerical solution of three-dimensional free-surface flows using a σ-coordinate model, a projection method and an unstructured finite-volume technique. The coordinate transformation is used in order to overcome difficulties arising from free surface elevation and irregular geometry. The projection method consists to combine the momentum and continuity equations in order to establish a Poisson-type equation for the non-hydrostatic pressure. A cell-centered finite volume method with a triangular mesh in the horizontal direction is used to simulate the flows with free-surfaces, in which the average values of conserved variables are stored at the centre of each element. A parallel algorithm is also presented for the finite volume discretization of the 3D Navier-Stokes equations. The proposed parallel method is formulated by using a multi-color SOR method, a block domain decomposition and interprocessor data communication techniques with Message Passing Interface. The model has been validated by several benchmarks which numerical simulations are in good agreement with the corresponding analytical and existing experimental results.
Mark, Clarisse I; Pike, G Bruce
2012-04-01
Deriving cerebral metabolic rate of oxygen consumption (CMRO(2)) from blood oxygenation level-dependent (BOLD) signals involves a flow-volume parameter (α), reflecting total cerebral blood volume changes, and a calibration constant (M). Traditionally, the former is assumed a fixed value and the latter is measured under alterations in fixed inspired fractional concentrations of carbon dioxide. We recently reported on reductions in M-variability via precise control of end-tidal pressures of both hypercapnic (HC) and hyperoxic (HO) gases. In light of these findings, our aim was to apply the improved calibration alternatives to neuronal activation, making use of their distinct vasoactive natures to evaluate the α-value. Nine healthy volunteers were imaged at 3 T while simultaneously measuring BOLD and arterial spin-labeling signals during controlled, graded, HC, and HO, followed by visual (VC) and sensorimotor cortices (SMC) activation. On the basis of low M- and CMRO(2)-variability, the comparison of these calibration alternatives accurately highlighted a reduced venous flow-volume relationship (α=0.16±0.02, with α(VC)=0.12±0.04, and α(SMC)=0.20±0.02), as appropriate for BOLD modeling.
Dynamic noise correction for IVUS quantitative volume blood flow: methods and numerical validation.
Lupotti, F.A.; Korte, C.L. de; Mastik, F.; Steen, A.F.W. van der
2002-01-01
In recent years, a new method to measure transverse blood flow based on the decorrelation of the radio-frequency (RF) signals, has been developed. Transverse blood flow estimation may be influenced by noise. In this paper, we investigated a new correlation-based method for noise correction. The deco
Howard, David L; Strobino, Donna; Sherman, Susan; Crum, Rosa
2008-07-01
There is still controversy surrounding the effectiveness of prenatal care in reducing low birthweight. In addition, very few studies have assessed the relationship between prenatal care and infant birthweight among pregnant women within the prison system. We sought to ascertain whether there is an association between the quantity of prenatal care and infant birthweight among pregnant women within such a setting. We examined the prison medical records of 147 infants born to women delivering at term (37-41 weeks of gestation) between 1 January 2002 and 31 December 2004 who were incarcerated during pregnancy in Texas state prisons. Linear regression was used to evaluate the association between the number of prison prenatal care visits and infant birthweight while adjusting for potential confounders (age, gravidity, maternal education, maternal race, history of substance use, history of alcohol use, history of tobacco use and the presence of any chronic disease). We also adjusted for the interaction between the gestational age at admission to prison and the number of prison prenatal care visits. There was a statistically significant 120.5 g increase in adjusted mean birthweight with each additional prison prenatal care visit (P = 0.001) among study infants whose mothers entered prison during the first trimester. This trend was not observed among women who came in after the first trimester. There appears to be a positive association between the amount of prison prenatal care and infant birthweight among incarcerated pregnant women delivering at term, but this association appears to be limited to women entering prison during the first trimester of pregnancy.
A calculation procedure for viscous flow in turbomachines, volume 3. [computer programs
Khalil, I.; Sheoran, Y.; Tabakoff, W.
1980-01-01
A method for analyzing the nonadiabatic viscous flow through turbomachine blade passages was developed. The field analysis is based upon the numerical integration of the full incompressible Navier-Stokes equations, together with the energy equation on the blade-to-blade surface. A FORTRAN IV computer program was written based on this method. The numerical code used to solve the governing equations employs a nonorthogonal boundary fitted coordinate system. The flow may be axial, radial or mixed and there may be a change in stream channel thickness in the through-flow direction. The inputs required for two FORTRAN IV programs are presented. The first program considers laminar flows and the second can handle turbulent flows. Numerical examples are included to illustrate the use of the program, and to show the results that are obtained.
DEFF Research Database (Denmark)
Lemmen, Josephine Gabriela; Pinborg, Anja; Rasmussen, S
2014-01-01
STUDY QUESTION: Is there a difference in birthweight distribution in ART singletons born after IVF culture in two different culture media? SUMMARY ANSWER: There is no effect of culture media on both crude and adjusted birthweight distributions in ART singletons from nulliparous mothers. WHAT...... IS KNOWN ALREADY: Studies on human ART singletons have reported a difference in birthweight in singletons following IVF culture in different culture media. However, other studies comparing different culture media have not shown any significant differences in birthweight. STUDY DESIGN, SIZE, DURATION...... culture media groups, we found the same slightly lower mean birthweight in IVF/ICSI singletons when compared with the national birth cohort as has been previously reported (Cook-d2 + Medicult-d2 + d3 versus birth cohort; girls: P
Directory of Open Access Journals (Sweden)
Hassan Badreddine
2017-01-01
Full Text Available The current work focuses on the development and application of a new finite volume immersed boundary method (IBM to simulate three-dimensional fluid flows and heat transfer around complex geometries. First, the discretization of the governing equations based on the second-order finite volume method on Cartesian, structured, staggered grid is outlined, followed by the description of modifications which have to be applied to the discretized system once a body is immersed into the grid. To validate the new approach, the heat conduction equation with a source term is solved inside a cavity with an immersed body. The approach is then tested for a natural convection flow in a square cavity with and without circular cylinder for different Rayleigh numbers. The results computed with the present approach compare very well with the benchmark solutions. As a next step in the validation procedure, the method is tested for Direct Numerical Simulation (DNS of a turbulent flow around a surface-mounted matrix of cubes. The results computed with the present method compare very well with Laser Doppler Anemometry (LDA measurements of the same case, showing that the method can be used for scale-resolving simulations of turbulence as well.
Directory of Open Access Journals (Sweden)
Amaziane Brahim
2014-07-01
Full Text Available In this paper, we consider adaptive numerical simulation of miscible displacement problems in porous media, which are modeled by single phase flow equations. A vertex-centred finite volume method is employed to discretize the coupled system: the Darcy flow equation and the diffusion-convection concentration equation. The convection term is approximated with a Godunov scheme over the dual finite volume mesh, whereas the diffusion-dispersion term is discretized by piecewise linear conforming finite elements. We introduce two kinds of indicators, both of them of residual type. The first one is related to time discretization and is local with respect to the time discretization: thus, at each time, it provides an appropriate information for the choice of the next time step. The second is related to space discretization and is local with respect to both the time and space variable and the idea is that at each time it is an efficient tool for mesh adaptivity. An error estimation procedure evaluates where additional refinement is needed and grid generation procedures dynamically create or remove fine-grid patches as resolution requirements change. The method was implemented in the software MELODIE, developed by the French Institute for Radiological Protection and Nuclear Safety (IRSN, Institut de Radioprotection et de Sûreté Nucléaire. The algorithm is then used to simulate the evolution of radionuclide migration from the waste packages through a heterogeneous disposal, demonstrating its capability to capture complex behavior of the resulting flow.
Parental factors in cognitive outcome of non-handicapped low birthweight infants.
Sommerfelt, K.; Ellertsen, B; Markestad, T.
1995-01-01
A population based cohort of 144 children weighing less than 2000 g who were without major handicap, and a random control sample of 163 children born at term and weighing over 3000 g were investigated. The aim was to assess the relative importance for cognitive development at 5 years of age, of birthweight, parental demographic factors, and factors related to the environment in which the child was reared. The mean non-verbal IQ was 6.1 points lower (95% CI, 2.3 to 10) for the low birthweight ...
Differentially Methylated Genomic Regions in Birth-Weight Discordant Twin Pairs
DEFF Research Database (Denmark)
Chen, Mubo; Baumbach, Jan; Vandin, Fabio
2016-01-01
twin pairs to find evidence for such “programming” effects, but no significant results emerged. We further investigated this issue using a new computational approach: Instead of probing single genomic sites for significant alterations in epigenetic marks, we scan for differentially methylated genomic...... regions. Whole genome DNA methylation levels were measured in whole blood from 150 pairs of adult identical twins discordant for birth-weight. Intrapair differential DNA methylation was associated with qualitative (large or small) and quantitative (percentage) birth-weight discordance at each genomic site...
1995-01-01
An evaluation of the effect of model inlet air temperature drift during a test run was performed to aid in the decision on the need for and/or the schedule for including heaters in the SRMAFTE. The Sverdrup acceptance test data was used to determine the drift in air temperature during runs over the entire range of delivered flow rates and pressures. The effect of this temperature drift on the model Reynolds number was also calculated. It was concluded from this study that a 2% change in absolute temperature during a test run could be adequately accounted for by the data analysis program. A handout package of these results was prepared and presented to ED35 management.
Energy Technology Data Exchange (ETDEWEB)
Marques Salgado, Cesar [Instituto de Engenharia Nuclear, DIRA/IEN/CNEN, Rio de Janeiro, CEP.: 21945-970-Caixa Postal 68550 (Brazil)], E-mail: otero@ien.gov.br; Brandao, Luis E.B. [Instituto de Engenharia Nuclear, DIRA/IEN/CNEN, Rio de Janeiro, CEP.: 21945-970-Caixa Postal 68550 (Brazil); Schirru, Roberto [Universidade Federal do Rio de Janeiro, PEN/COPPE-DNC/EE-CT, Rio de Janeiro, CEP.: 21941-972-Caixa Postal 68509 (Brazil); Pereira, Claudio M.N.A. [Instituto de Engenharia Nuclear, DIRA/IEN/CNEN, Rio de Janeiro, CEP.: 21945-970-Caixa Postal 68550 (Brazil); Silva, Ademir Xavier da [Universidade Federal do Rio de Janeiro, PEN/COPPE-DNC/EE-CT, Rio de Janeiro, CEP.: 21941-972-Caixa Postal 68509 (Brazil); Ramos, Robson [Instituto de Engenharia Nuclear, DIRA/IEN/CNEN, Rio de Janeiro, CEP.: 21945-970-Caixa Postal 68550 (Brazil)
2009-10-15
This work presents methodology based on nuclear technique and artificial neural network for volume fraction predictions in annular, stratified and homogeneous oil-water-gas regimes. Using principles of gamma-ray absorption and scattering together with an appropriate geometry, comprised of three detectors and a dual-energy gamma-ray source, it was possible to obtain data, which could be adequately correlated to the volume fractions of each phase by means of neural network. The MCNP-X code was used in order to provide the training data for the network.
The Institute for Mathematics and its Applications. Volume 68, Flow Control,
1994-01-01
Avner FriedIT0a1, Volume 17: Applicatio:n_ ol’ Couiibinatorics and Graph ThEor, to the Biological and Social Scit-nc’es Editor: Frcd Rc,herts Volume 18...Foundation and Office of Naval Ec•careh whose financial support made the workshop poss)h!e. Avner l’¥iedman Willard Miller. Jr. i xi PRErACE This...interested in models and methodologies which treat trait- " The research of KI.1B. was supported in pprt bv the Air Force Office .f Scientifie Research
Numerical study of impeller-driven von Karman flows via a volume penalization method
Kreuzahler, Sebastian; Homann, Holger; Ponty, Yannick; Grauer, Rainer
2013-01-01
Simulations of impeller-driven flows in cylindrical geometry are performed via direct numerical simulations (DNS) and compared to flows obtained in the von Karman flow experiments. The geometry of rotating impellers assembled of several basic geometric objects is modeled via a penalization method and implemented in a massive parallel pseudo-spectral Navier-Stokes solver. We performed simulations of impellers with different curvature of blades, especially one resembling the so-called TM28 configuration used in water experiments. The decomposition into poloidal, toroidal components and the mean velocity fields from our simulations are quantitatively in agreement with experimental results. We analyzed the flow structure close to the impeller blades and found different vortex topologies.
DEFF Research Database (Denmark)
Troldborg, Niels; Sørensen, Niels N.; Réthoré, Pierre-Elouan;
2015-01-01
This paper describes a consistent algorithm for eliminating the numerical wiggles appearing when solving the finite volume discretized Navier-Stokes equations with discrete body forces in a collocated grid arrangement. The proposed method is a modification of the Rhie-Chow algorithm where the force...... in a cell is spread on neighboring cells by applying equivalent pressure jumps at the cell faces. The method shows excellent results when applied for simulating the flow through an actuator disk, which is relevant for wind turbine wake simulations. (c) 2015 Elsevier Ltd. All rights reserved....
Directory of Open Access Journals (Sweden)
Arheden Håkan
2011-04-01
Full Text Available Abstract Background Functional and morphological changes of the heart influence blood flow patterns. Therefore, flow patterns may carry diagnostic and prognostic information. Three-dimensional, time-resolved, three-directional phase contrast cardiovascular magnetic resonance (4D PC-CMR can image flow patterns with unique detail, and using new flow visualization methods may lead to new insights. The aim of this study is to present and validate a novel visualization method with a quantitative potential for blood flow from 4D PC-CMR, called Volume Tracking, and investigate if Volume Tracking complements particle tracing, the most common visualization method used today. Methods Eight healthy volunteers and one patient with a large apical left ventricular aneurysm underwent 4D PC-CMR flow imaging of the whole heart. Volume Tracking and particle tracing visualizations were compared visually side-by-side in a visualization software package. To validate Volume Tracking, the number of particle traces that agreed with the Volume Tracking visualizations was counted and expressed as a percentage of total released particles in mid-diastole and end-diastole respectively. Two independent observers described blood flow patterns in the left ventricle using Volume Tracking visualizations. Results Volume Tracking was feasible in all eight healthy volunteers and in the patient. Visually, Volume Tracking and particle tracing are complementary methods, showing different aspects of the flow. When validated against particle tracing, on average 90.5% and 87.8% of the particles agreed with the Volume Tracking surface in mid-diastole and end-diastole respectively. Inflow patterns in the left ventricle varied between the subjects, with excellent agreement between observers. The left ventricular inflow pattern in the patient differed from the healthy subjects. Conclusion Volume Tracking is a new visualization method for blood flow measured by 4D PC-CMR. Volume Tracking
Moortgat, Joachim; Soltanian, Mohamad Reza
2016-01-01
We present a new implicit higher-order finite element (FE) approach to efficiently model compressible multicomponent fluid flow on unstructured grids and in fractured porous subsurface formations. The scheme is sequential implicit: pressures and fluxes are updated with an implicit Mixed Hybrid Finite Element (MHFE) method, and the transport of each species is approximated with an implicit second-order Discontinuous Galerkin (DG) FE method. Discrete fractures are incorporated with a cross-flow equilibrium approach. This is the first investigation of all-implicit higher-order MHFE-DG for unstructured triangular, quadrilateral (2D), and hexahedral (3D) grids and discrete fractures. A lowest-order implicit finite volume (FV) transport update is also developed for the same grid types. The implicit methods are compared to an Implicit-Pressure-Explicit-Composition (IMPEC) scheme. For fractured domains, the unconditionally stable implicit transport update is shown to increase computational efficiency by orders of mag...
DEFF Research Database (Denmark)
Iida, H; Law, I; Pakkenberg, B
2000-01-01
formulated four mathematical models that describe the dynamic behavior of a freely diffusible tracer (H215O) in a region of interest (ROI) incorporating estimates of regional tissue flow that are independent of PVE. The current study was intended to evaluate the feasibility of these models and to establish...... a methodology to accurately quantify regional cerebral blood flow (CBF) corrected for PVE in cortical gray matter regions. Five monkeys were studied with PET after IV H2(15)O two times (n = 3) or three times (n = 2) in a row. Two ROIs were drawn on structural magnetic resonance imaging (MRI) scans and projected...... onto the PET images in which regional CBF values and the water perfusable tissue fraction for the cortical gray matter tissue (hence the volume of gray matter) were estimated. After the PET study, the animals were killed and stereologic analysis was performed to assess the gray matter mass...
Evaluation of volume vascularization index and flow index: a phantom study.
Schulten-Wijman, M.J.; Struijk, P.C.; Brezinka, C.; Jong, N De; Steegers, E.A.P.
2008-01-01
OBJECTIVES: Three-dimensional (3D) power Doppler ultrasonography provides indices to quantify moving blood within a volume of interest (e.g. ovary, endometrium, tumor or placenta). The purpose of this study was to determine the influence of ultrasound instrument settings on vascularization index (VI
Evaluation of volume vascularization index and flow index: A phantom study
M.J.N.C. Schulten-Wijman; P.C. Struijk (Pieter); C.A. Brezinka (Christoph); N. de Jong (Nico); R.P.M. Steegers-Theunissen (Régine)
2008-01-01
textabstractObjectives Three-dimensional (3D) power Doppler ultrasonography provides indices to quantify moving blood within a volume of interest (e.g. ovary, endometrium, tumor or placenta). The purpose of this study was to determine the influence of ultrasound instrument settings on vascularizatio
Directory of Open Access Journals (Sweden)
Chun-Jen Lin
2014-04-01
Conclusion: The results of our study indicated that low RBC volume may play an important role in the pathophysiology of OI in this group of patients. Moreover, its role seems even more relevant in patients with POTS than in those without. Further studies for mechanistic evaluation are needed in the future.
It is generally accepted that monitoring wells must be purged to access formation water to obtain “representative” ground water quality samples. Historically anywhere from 3 to 5 well casing volumes have been removed prior to sample collection to evacuate the standing well water...
Dissociation of Blood Volume and Flow in Regulation of Salt and Water Balance in Burn Patients,
1991-09-01
arterial capacity, which is underfilled at sites of lower than in the patients in the present study (276 versus hormone control. 286 mosm/kg). The serum...well as looking at given ability to concentrate their urine and lower their voiding volume 02 consumption measured by indirect calorimetry. at night, I
Effect of vitamin A supplementation on morbidity of low-birthweight ...
African Journals Online (AJOL)
Effect of vitamin A supplementation on morbidity of low-birthweight neonates. ... Low-birth-weight (LBW) infants « 2 500 g) are at increased risk of respiratory infection in ... After adjusting for risk factors this difference was no longer significant.
Maternal homocysteine and related B vitamins as risk factors for low birthweight.
Hogeveen, M.; Blom, H.J.; Heijden, E.H.M. van der; Semmekrot, B.A.; Sporken, J.M.J.; Ueland, P.M.; Heijer, M. den
2010-01-01
OBJECTIVE: We designed a large prospective study to explore the relationship between maternal homocysteine concentrations and related B vitamins and birthweight. STUDY DESIGN: Blood was sampled from pregnant women at 30-34 weeks of gestation and their newborn infants (n = 366). RESULTS:
Birthweight and mortality in adulthood: a systematic review and meta-analysis
DEFF Research Database (Denmark)
Risnes, Kari R; Vatten, Lars J; Baker, Jennifer L;
2011-01-01
results. METHODS: The Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines for conducting and reporting meta-analysis of observational studies were followed. We retrieved 22 studies that assessed the association between birthweight and adult mortality from all causes, CVD or cancer...
Kleine, M.J. de; Nijhuis-Van der Sanden, M.W.G.; Ouden, A.L. den
2006-01-01
AIM: To determine whether paediatricians that examine, in regular clinical practice, very preterm and very-low-birthweight children at 5 y of age detect neurological impairments and functional motor problems in these children. METHODS: We compared a paediatric judgement, a standardized neurological
Human embryonic growth trajectories and associations with fetal growth and birthweight
van Uitert, Evelyne M.; Exalto, Niek; Burton, Graham J.; Willemsen, Sten P.; Koning, Anton H. J.; Eilers, Paul H. C.; Laven, Joop S. E.; Steegers, Eric A. P.; Steegers-Theunissen, Regine P. M.
2013-01-01
How do human embryonic growth trajectories evolve in the first trimester, and is first-trimester embryonic growth associated with fetal growth and birthweight (BW)? Human embryonic growth rates increase between 9 and 10 weeks of gestation and are associated with mid-pregnancy fetal growth and BW. Fe
Kleine, M.J. de; Nijhuis-Van der Sanden, M.W.G.; Ouden, A.L. den
2006-01-01
AIM: To determine whether paediatricians that examine, in regular clinical practice, very preterm and very-low-birthweight children at 5 y of age detect neurological impairments and functional motor problems in these children. METHODS: We compared a paediatric judgement, a standardized neurological
Association between paternal schizophrenia and low birthweight:ADAM12 may matter
Institute of Scientific and Technical Information of China (English)
Hans-Gert Bernstein; Susan Müller; Johann Steiner; Nadine Farkas; Bernhard Bogerts; Uwe Lendeckel
2010-01-01
@@ Dear Editor, I am Dr Hans-Gert Bernstein from the Department of Psychiatry, University of Magdeburg, Germany.Although it is now a well-established fact that mothers with schizophrenia are at higher risk for obstetric complications (preterm births, preeclampsia, low birthweight [LBW] and small-for-gestational-age babies), a putative paternal impact was largely ignored until recently.
Tiemersma, Sybrich; Heistein, Julia; Ruijne, Roos; Lopez, Gustavo; van Lobenstein, Jeroen; van Rheenen, Patrick
OBJECTIVE: To evaluate safety and haematological effects of delayed cord clamping (DCC) in infants with expected low birthweight born in a resource-poor setting. METHODS: Randomised controlled trial involving pregnant women in early labour ≥18 years with intrapartum symphysal-fundal height ≤32 cm.
Birthweight percentiles for twin birth neonates by gestational age in China
Zhang, Bin; Cao, Zhongqiang; Zhang, Yiming; Yao, Cong; Xiong, Chao; Zhang, Yaqi; Wang, Youjie; Zhou, Aifen
2016-01-01
Localized birthweight references for gestational ages serve as an essential tool in accurate evaluation of atypical birth outcomes. Such references for twin births are currently not available in China. The aim of this study was to construct up-to-data sex specific birth weight references by gestational ages for twin births in China. We conducted a population-based analysis on the data of 22,507 eligible living twin infants with births dated between 8/01/2006 and 8/31/2015 from all 95 hospitals within the Wuhan area. Gestational ages in complete weeks were determined using a combination of last-menstrual-period based (LMP) estimation and ultrasound examination. Smoothed percentile curves were created by the Lambda Mu Sigma (LMS) method. Reference of the 3rd, 10th, 25th, 50th, 75th, 90th, 97th percentiles birth weight by sex and gestational age were made using 11,861 male and 10,646 female twin newborns with gestational age 26–42 weeks. Separate birthweight percentiles curves for male and female twins were constructed. In summary, our study firstly presents percentile curves of birthweight by gestational age for Chinese twin neonates. Further research is required for the validation and implementation of twin birthweight curves into clinical practice. PMID:27506479
Maternal homocysteine and related B vitamins as risk factors for low birthweight.
Hogeveen, M.; Blom, H.J.; Heijden, E.H.M. van der; Semmekrot, B.A.; Sporken, J.M.J.; Ueland, P.M.; Heijer, M. den
2010-01-01
OBJECTIVE: We designed a large prospective study to explore the relationship between maternal homocysteine concentrations and related B vitamins and birthweight. STUDY DESIGN: Blood was sampled from pregnant women at 30-34 weeks of gestation and their newborn infants (n = 366). RESULTS: Concentratio
Motor Coordination Difficulties and Physical Fitness of Extremely-Low-Birthweight Children
Burns, Yvonne R.; Danks, Marcella; O'Callaghan, Michael J.; Gray, Peter H.; Cooper, David; Poulsen, Leith; Watter, Pauline
2009-01-01
Motor coordination difficulties and poor fitness exist in the extremely low birthweight (ELBW) population. This study investigated the relative impact of motor coordination on the fitness of ELBW children aged 11 to 13 years. One hundred and nine children were recruited to the study: 54 ELBW participants (mean age at assessment 12y 6mo; 31 male,…
Epigenetic programming of adipose-derived stem cells in low birthweight individuals
DEFF Research Database (Denmark)
Broholm, Christa; Olsson, Anders H; Perfilyev, Alexander
2016-01-01
AIMS/HYPOTHESIS: Low birthweight (LBW) is associated with dysfunctions of adipose tissue and metabolic disease in adult life. We hypothesised that altered epigenetic and transcriptional regulation of adipose-derived stem cells (ADSCs) could play a role in programming adipose tissue dysfunction...
Teenage smoking in pregnancy and birthweight: a population study, 2001-2004.
Chan, Denise L; Sullivan, Elizabeth A
2008-04-07
To determine the association between smoking in pregnant teenagers and baby birthweight. A retrospective population-based study of women aged teenage smokers was 9.9%, compared with 6.0% in babies born to teenage non-smokers (odds ratio [OR], 1.72 [95% CI, 1.57-1.90]). On average, babies born to teenage smokers were 179.8 g lower in birthweight than babies born to teenage non-smokers (95% CI, 165.5 -194.1 g; t = 24.6, P 1.3; P Teenagers smoking > 10 cigarettes a day had babies with lower birthweight that those who smoked relationship. The babies of teenage smokers who stopped smoking before 20 weeks' gestation had birthweights similar to those of babies born to teenage non-smokers. One in 15 teenage smokers stopped smoking during pregnancy. Babies whose mothers smoked during pregnancy were more likely to have LBW than babies whose mothers did not smoke. Mothers who continue to smoke in the second half of pregnancy increase their baby's risk of LBW. There is significant scope to improve the quitting rate, and health professionals need to target smoking cessation at all contacts with pregnant women who continue to smoke.
An overlapped grid method for multigrid, finite volume/difference flow solvers: MaGGiE
Baysal, Oktay; Lessard, Victor R.
1990-01-01
The objective is to develop a domain decomposition method via overlapping/embedding the component grids, which is to be used by upwind, multi-grid, finite volume solution algorithms. A computer code, given the name MaGGiE (Multi-Geometry Grid Embedder) is developed to meet this objective. MaGGiE takes independently generated component grids as input, and automatically constructs the composite mesh and interpolation data, which can be used by the finite volume solution methods with or without multigrid convergence acceleration. Six demonstrative examples showing various aspects of the overlap technique are presented and discussed. These cases are used for developing the procedure for overlapping grids of different topologies, and to evaluate the grid connection and interpolation data for finite volume calculations on a composite mesh. Time fluxes are transferred between mesh interfaces using a trilinear interpolation procedure. Conservation losses are minimal at the interfaces using this method. The multi-grid solution algorithm, using the coaser grid connections, improves the convergence time history as compared to the solution on composite mesh without multi-gridding.
Institute of Scientific and Technical Information of China (English)
LI XiangYang; WANG YueFa; YU GengZhi; YANG Chao; MAO ZaiSha
2008-01-01
A volume-amending method is developed both to keep the level set function as an algebraic distance function and to preserve the bubble mass in a level set approach for incompressible two-phase flows with the significantly deformed free interface. After the traditional reinitialization procedure, a vol-ume-amending method is added for correcting the position of the interface according to mass loss/gain error until the mass error falls in the allowable range designated in advance. The level set approach with this volume-amending method incorporated has been validated by three test cases: the motion of a single axisymmetrical bubble or drop in liquid, the motion of a two-dimensional water drop falling through the air into a water pool, and the interactional motion of two buoyancy-driven three-dimensional deformable bubbles. The computational results with this volume-amending method in-corporated are in good agreement with the reported experimental data and the mass is well preserved in all cases.
Winston, Ryan J; Dorsey, Jay D; Hunt, William F
2016-05-15
Green infrastructure aims to restore watershed hydrologic function by more closely mimicking pre-development groundwater recharge and evapotranspiration (ET). Bioretention has become a popular stormwater control due to its ability to reduce runoff volume through these pathways. Three bioretention cells constructed in low permeability soils in northeast Ohio were monitored for non-winter quantification of inflow, drainage, ET, and exfiltration. The inclusion of an internal water storage (IWS) zone allowed the three cells to reduce runoff by 59%, 42%, and 36% over the monitoring period, in spite of the tight underlying soils. The exfiltration rate and the IWS zone thickness were the primary determinants of volume reduction performance. Post-construction measured drawdown rates were higher than pre-construction soil vertical hydraulic conductivity tests in all cases, due to lateral exfiltration from the IWS zones and ET, which are not typically accounted for in pre-construction soil testing. The minimum rainfall depths required to produce outflow for the three cells were 5.5, 7.4, and 13.8mm. During events with 1-year design rainfall intensities, peak flow reduction varied from 24 to 96%, with the best mitigation during events where peak rainfall rate occurred before the centroid of the rainfall volume, when adequate bowl storage was available to limit overflow.
Saad, Bilal Mohammed
2014-06-28
We propose and analyze a combined finite volume-nonconforming finite element scheme on general meshes to simulate the two compressible phase flow in porous media. The diffusion term, which can be anisotropic and heterogeneous, is discretized by piecewise linear nonconforming triangular finite elements. The other terms are discretized by means of a cell-centered finite volume scheme on a dual mesh, where the dual volumes are constructed around the sides of the original mesh. The relative permeability of each phase is decentred according the sign of the velocity at the dual interface. This technique also ensures the validity of the discrete maximum principle for the saturation under a non restrictive shape regularity of the space mesh and the positiveness of all transmissibilities. Next, a priori estimates on the pressures and a function of the saturation that denote capillary terms are established. These stabilities results lead to some compactness arguments based on the use of the Kolmogorov compactness theorem, and allow us to derive the convergence of a subsequence of the sequence of approximate solutions to a weak solution of the continuous equations, provided the mesh size tends to zero. The proof is given for the complete system when the density of the each phase depends on its own pressure. © 2014 Springer-Verlag Berlin Heidelberg.
Institute of Scientific and Technical Information of China (English)
2008-01-01
A volume-amending method is developed both to keep the level set function as an algebraic distance function and to preserve the bubble mass in a level set approach for incompressible two-phase flows with the significantly deformed free interface. After the traditional reinitialization procedure, a vol-ume-amending method is added for correcting the position of the interface according to mass loss/gain error until the mass error falls in the allowable range designated in advance. The level set approach with this volume-amending method incorporated has been validated by three test cases: the motion of a single axisymmetrical bubble or drop in liquid, the motion of a two-dimensional water drop falling through the air into a water pool, and the interactional motion of two buoyancy-driven three- dimensional deformable bubbles. The computational results with this volume-amending method in-corporated are in good agreement with the reported experimental data and the mass is well preserved in all cases.
Mayrovitz, Harvey N; Guo, Xiaoran; Salmon, Mark; Uhde, Matt
2013-01-01
Skin tissue dielectric constant (TDC) values measured via the open-ended coaxial probe method are useful non-invasive indices of local skin tissue water. However, the effect of skin blood flow (SBF) or skin blood volume (SBV) on TDC values is unknown. To determine the magnitude of such effects, we decreased forearm SBV via vertical arm raising for 5 min (test 1) and increased SBV by bicep cuff compression to 50 mmHg for 5 min (test 2) in 20 healthy supine subjects (10 men). TDC values were measured to a depth of 1·5 mm on anterior forearm, and SBF was measured with laser-Doppler system simultaneously on forearm and finger. Results indicate that decreasing vascular volume (test 1) was associated with a small but statistically significant reduction in TDC (3·0 ± 4·3%, P = 0·003) and increasing vascular volume (test 2) was associated with a slight but statistically significant increase in TDC (3·5 ± 3·0%, PTDC values (3·0-3·5%) over the wide range of induced SBV and SBF changes suggest a minor effect on clinically determined TDC values because of SBV or SBF changes or differences when comparing TDC longitudinally over time or among individuals of different groups in a research setting.
DEFF Research Database (Denmark)
Hansen, Susan; Dahl, Ronald; Hoffmann, Hans Jürgen
2008-01-01
Flow cytometers have a constant flow rate. This enables flow cytometers to measure leukocyte concentrations in a determined volume by acquiring data at a fixed rate over a fixed time and is called constant volume acquisition (CVA). The volume aspirated by a FACS Calibur flow cytometer in 4 min...... at a high rate has a median of 163 microl (IQR 156-170) with TruCount tubes. Leukocyte concentrations of 26 healthy volunteers were measured twice on up to four occasions with a Bürker-Türk chamber, by single platform technology (SPT) with TruCount tubes and on the same data set using CVA. Total leukocyte...... concentrations determined by CVA correlated better with measurements in a Bürker-Türk (BT) chamber than with SPT. Concentrations determined with CVA were 1.86% higher than with BT whereas SPT data were 5.35% higher than BT (pCVA (p
León, Gemma; Murcia, Mario; Rebagliato, Marisa; Álvarez-Pedrerol, Mar; Castilla, Ane M; Basterrechea, Mikel; Iñiguez, Carmen; Fernández-Somoano, Ana; Blarduni, Elizabeth; Foradada, Carles M; Tardón, Adonina; Vioque, Jesús
2015-03-01
Maternal clinical thyroid disorders can cause reproductive complications. However, the effects of mild thyroid dysfunctions are not yet well established. The aim was to evaluate the association of maternal thyroid function during the first half of pregnancy with birthweight and preterm delivery. We analysed data on 2170 pregnant women and their children from a prospective population-based cohort study in four Spanish areas. Mid-gestation maternal serum and urine samples were gathered to determine thyroid-stimulating hormone (TSH), free thyroxine (fT4 ), and urinary iodine concentration (UIC). Thyroid status was defined according to percentile distribution as: euthyroid (TSH and fT4 >5th and 95th percentile and fT4 normal or 95 th percentile and TSH normal), and hyperthyroidism (TSH 95th percentile). Response variables were birthweight, small and large for gestational age (SGA/LGA), and preterm delivery. An inverse association of fT4 and TSH with birthweight was found, the former remaining when restricted to euthyroid women. High fT4 levels were also associated with an increased risk of SGA [odds ratio, 95% confidence interval (CI) 1.28 (95% CI 1.08, 1.51)]. Mean birthweight was higher in the hypothyroxinaemic group (β = 109, P < 0.01). Iodine intake and UIC were not associated with birth outcomes. High maternal fT4 levels during the first half of pregnancy were related to lower birthweight and increased risk of SGA newborns, suggesting that maternal thyroid function may affect fetal growth, even within the normal range. © 2015 John Wiley & Sons Ltd.
New birthweight charts according to parity and type of delivery for the Spanish population.
Terán, José Manuel; Varea, Carlos; Bernis, Cristina; Bogin, Barry; González-González, Antonio
Birthweight by gestational age charts enable fetal growth to be evaluated in a specific population. Given that maternal profile and obstetric practice have undergone a remarkable change over the past few decades in Spain, this paper presents new Spanish reference percentile charts stratified by gender, parity and type of delivery. They have been prepared with data from the 2010-2014 period of the Spanish Birth Statistics Bulletin. Reference charts have been prepared using the LMS method, corresponding to 1,428,769 single, live births born to Spanish mothers. Percentile values and mean birth weight are compared among newborns according to gender, parity and type of delivery. Newborns to primiparous mothers show significantly lower birthweight than those born to multiparous mothers (p<0.036). Caesarean section was associated with a substantially lower birthweight in preterm births (p<0.048), and with a substantially higher birthweight for full-term deliveries (p<0.030). Prevalence of small for gestational age is significantly higher in newborns born by Caesarean section, both in primiparous (p<0.08) and multiparous mothers (p<0.027) and, conversely, the prevalence of large for gestational age among full-term births is again greater both in primiparous (p<0.035) and in multiparous mothers (p<0.007). Results support the consideration of establishing parity and type of delivery-specific birthweight references. These new charts enable a better evaluation of the impact of the demographic, reproductive and obstetric trends currently in Spain on fetal growth. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.
Directory of Open Access Journals (Sweden)
Sol Pía Juárez
Full Text Available Maternal smoking during pregnancy (SDP seems associated with reduced birthweight in the offspring. This observation, however, is based on conventional epidemiological analyses, and it might be confounded by unobserved maternal characteristics related to both smoking habits and offspring birth weight. Therefore, we apply a quasi-experimental sibling analysis to revisit previous findings. Using the Swedish Medical Birth Register, we identified 677,922 singletons born between 2002 and 2010 from native Swedish mothers. From this population, we isolated 62,941 siblings from 28,768 mothers with discrepant habits of SDP. We applied conventional and mother-specific multilevel linear regression models to investigate the association between maternal SDP and offspring birthweight. Depending on the mother was light or heavy smoker and the timing of exposition during pregnancy (i.e., first or third trimester, the effect of smoking on birthweight reduction was between 6 and 78 g less marked in the sibling analysis than in the conventional analysis. Sibling analysis showed that continuous smoking reduces birthweight by 162 grams for mothers who were light smokers (1 to 9 cigarettes per day and 226 g on average for those who were heavy smokers throughout the pregnancy in comparison to non-smoker mothers. Quitting smoking during pregnancy partly counteracted the smoking-related birthweight reduction by 1 to 29 g, and a subsequent smoking relapse during pregnancy reduced birthweight by 77 to 83 g. The sibling analysis provides strong evidence that maternal SDP reduces offspring birthweight, though this reduction was not as great as that observed in the conventional analysis. Our findings support public health interventions aimed to prevent SDP and to persuade those who already smoke to quit and not relapse throughout the pregnancy. Besides, further analyses are needed in order to explain the mechanisms through which smoking reduces birthweight and to identify
Moortgat, Joachim; Amooie, Mohammad Amin; Soltanian, Mohamad Reza
2016-10-01
We present a new implicit higher-order finite element (FE) approach to efficiently model compressible multicomponent fluid flow on unstructured grids and in fractured porous subsurface formations. The scheme is sequential implicit: pressures and fluxes are updated with an implicit Mixed Hybrid Finite Element (MHFE) method, and the transport of each species is approximated with an implicit second-order Discontinuous Galerkin (DG) FE method. Discrete fractures are incorporated with a cross-flow equilibrium approach. This is the first investigation of all-implicit higher-order MHFE-DG for unstructured triangular, quadrilateral (2D), and hexahedral (3D) grids and discrete fractures. A lowest-order implicit finite volume (FV) transport update is also developed for the same grid types. The implicit methods are compared to an Implicit-Pressure-Explicit-Composition (IMPEC) scheme. For fractured domains, the unconditionally stable implicit transport update is shown to increase computational efficiency by orders of magnitude as compared to IMPEC, which has a time-step constraint proportional to the pore volume of discrete fracture grid cells. However, when lowest-order Euler time-discretizations are used, numerical errors increase linearly with the larger implicit time-steps, resulting in high numerical dispersion. Second-order Crank-Nicolson implicit MHFE-DG and MHFE-FV are therefore presented as well. Convergence analyses show twice the convergence rate for the DG methods as compared to FV, resulting in two to three orders of magnitude higher computational efficiency. Numerical experiments demonstrate the efficiency and robustness in modeling compressible multicomponent flow on irregular and fractured 2D and 3D grids, even in the presence of fingering instabilities.
DEFF Research Database (Denmark)
Dahl, Marianne; Kamper, Jens
2006-01-01
AIM: To describe physical outcome and school performance in a cohort of very-low-birthweight infants treated with early nasal continuous positive airway pressure (NCPAP)/minimal handling regimen with permissive hypercapnia, in comparison to siblings of normal birthweight. MATERIAL AND METHODS......: Neonatal and follow-up data from 213 very-low-birthweight infants from 1983-1988 were registered and a questionnaire concerning school achievements was sent to the families of survivors and siblings attending school. RESULTS: Mortality was 22%. Of the survivors, 4% had moderate-severe and 9% mild sequelae...
Joyce, T; Grossman, M
1990-11-01
We use a vector autoregression to examine the dynamic relationship between the race-specific percentage of pregnancies terminated by induced abortion and the race-specific percentage of low-birthweight births in New York City. With monthly data beginning in 1972, we find that induced abortion explains low birthweight for blacks, but not for whites. There is no evidence of feedback from low birthweight to induced abortion. The findings suggest that unanticipated decreases in the percentage of pregnancies terminated by induced abortion would worsen birth outcomes among blacks in New York City.
A control-volume method for analysis of unsteady thrust augmenting ejector flows
Drummond, Colin K.
1988-01-01
A method for predicting transient thrust augmenting ejector characteristics is presented. The analysis blends classic self-similar turbulent jet descriptions with a control volume mixing region discretization to solicit transient effects in a new way. Division of the ejector into an inlet, diffuser, and mixing region corresponds with the assumption of viscous-dominated phenomenon in the latter. Inlet and diffuser analyses are simplified by a quasi-steady analysis, justified by the assumptions that pressure is the forcing function in those regions. Details of the theoretical foundation, the solution algorithm, and sample calculations are given.
Verification of a binary fluid solidification model in the finite-volume flow solver
Waclawczyk, Tomasz
2015-01-01
The aim of this paper is to verify the new numerical implementation of a binary fluid, heat conduction dominated solidification model. First, we extend a semi-analytical solution to the heat diffusion equation, next, the range of its applicability is investigated. It was found that the linearization introduced to the heat diffusion equation negatively affects the ability to predict solidus and liquidus lines positions whenever the magnitude of latent heat of fusion exceeds a certain value. Next, a binary fluid solidification model is coupled with a flow solver, and is used in a numerical study of Al-4.1%Cu alloy solidification in a two-dimensional rectangular cavity. An accurate coupling between the solidification model and the flow solver is crucial for the correct forecast of solidification front positions and macrosegregation patterns.
Investigation of the free flow electrophoretic process. Volume 2: Technical analysis
Weiss, R. A.; Lanham, J. W.; Richman, D. W.; Walker, C. D.
1979-01-01
The effect of gravity on the free flow electrophoretic process was investigated. The demonstrated effects were then compared with predictions made by mathematical models. Results show that the carrier buffer flow was affected by gravity induced thermal convection and that the movement of the separating particle streams was affected by gravity induced buoyant forces. It was determined that if gravity induced buoyant forces were included in the mathematical models, then effective predictions of electrophoresis chamber separation performance were possible. The results of tests performed using various methods of electrophoresis using supportive media show that the mobility and the ability to separate were essentially independent of concentration, providing promise of being able to perform electrophoresis with higher inlet concentrations in space.
1995-01-01
The purpose of the RSRM Nozzle Slag Ejection Precursor Test is to investigate the effect that slag ejection from the RSRM nozzle has on the chamber pressure and trust of the SRB's. In past firings of the Reusable Solid Rocket Motor (RSRM) both static test and flight motors have shown small pressure perturbations occurring primarily between 65 and 80 seconds. A joint NASA/Thiokol team investigation concluded that the cause of the pressure perturbations was the periodic ingestion and ejection of molten aluminum oxide slag from the cavity around the submerged nozzle nose which tends to trap and collect individual aluminum oxide droplets from the approach flow. The conclusions of the team were supported by numerous data and observations from special tests including high speed photographic films, real time radiography, plume calorimeters, accelerometers, strain gauges, nozzle TVC system force gauges, and motor pressure and thrust data. A simplistic slag ballistics model was formulated to relate a given pressure perturbation to a required slag quantity. Also, a cold flow model using air and water was developed to provide data on the relationship between the slag flow rate and the chamber pressure increase. Both the motor and the cold flow model exhibited low frequency oscillations in conjunction with periods of slag ejection. Motor and model frequencies were related to scaling parameters. The data indicate that there is a periodicity to the slag entrainment and ejection phenomena which is possibly related to organized oscillations from instabilities in the dividing streamline shear layer which impinges on the underneath surface of the nozzle.
Institute of Scientific and Technical Information of China (English)
HEJRANFAR Kazem; FATTAH-HESARY Kasra
2011-01-01
A numerical treatment for the prediction of cavitating flows is presented and assessed.The algorithm uses the preconditioned multiphase Euler equations with appropriate mass transfer terms.A central difference finite volume scheme with suitable dissipation terms to account for density jumps across the cavity interface is shown to yield an effective method for solving the multiphase Euler equations.The Euler equations are utilized herein for the cavitation modeling, because some certain characteristics of cavitating flows can be obtained using the solution of this system of equations with relative low computational effort.In addition, the Euler equations are appropriate for the assessment of the numerical method used, because of the sensitivity of the solution to the numerical instabilities.For this reason, a sensitivity study is conducted to evaluate the effects of various parameters, such as numerical dissipation coefficients and grid size, on the accuracy and performance of the solution.The computations are performed for steady cavitating flows around the NACA 0012 and NACA 66 (MOD) hydrofoils and also an axisymmetric hemispherical fore-body under different conditions and the results are compared with the available numerical and experimental data.The solution procedure presented is shown to be accurate and efficient for predicting steady sheet- and super-cavitation for 2D/axisymmetric geometries.
A finite-volume module for simulating global all-scale atmospheric flows
Smolarkiewicz, Piotr K.; Deconinck, Willem; Hamrud, Mats; Kühnlein, Christian; Mozdzynski, George; Szmelter, Joanna; Wedi, Nils P.
2016-06-01
The paper documents the development of a global nonhydrostatic finite-volume module designed to enhance an established spectral-transform based numerical weather prediction (NWP) model. The module adheres to NWP standards, with formulation of the governing equations based on the classical meteorological latitude-longitude spherical framework. In the horizontal, a bespoke unstructured mesh with finite-volumes built about the reduced Gaussian grid of the existing NWP model circumvents the notorious stiffness in the polar regions of the spherical framework. All dependent variables are co-located, accommodating both spectral-transform and grid-point solutions at the same physical locations. In the vertical, a uniform finite-difference discretisation facilitates the solution of intricate elliptic problems in thin spherical shells, while the pliancy of the physical vertical coordinate is delegated to generalised continuous transformations between computational and physical space. The newly developed module assumes the compressible Euler equations as default, but includes reduced soundproof PDEs as an option. Furthermore, it employs semi-implicit forward-in-time integrators of the governing PDE systems, akin to but more general than those used in the NWP model. The module shares the equal regions parallelisation scheme with the NWP model, with multiple layers of parallelism hybridising MPI tasks and OpenMP threads. The efficacy of the developed nonhydrostatic module is illustrated with benchmarks of idealised global weather.
Energy Technology Data Exchange (ETDEWEB)
Kubo, Toshikazu; Kimori, Kokuto; Nakamura, Fuminori; Inoue, Shigehiro; Fujioka, Mikihiro; Ueshima, Keiichiro; Hirasawa, Yasusuke; Ushijima, Yo; Nishimura, Tsunehiko [Kyoto Prefectural Univ. of Medicine (Japan)
2001-06-01
To deepen understanding of hemodynamics in the femoral head, i.e., the essential factor in clarifying pathogenesis of hip disorders, this study examined blood flow and blood volume in the femoral heads of healthy adults, and their changes with age, by using positron emission tomography (PET). In 16 healthy adult males (age: 20-78 years old, mean age: 42 years), blood flow was measured by means of the H{sub 2}{sup 15}O dynamic study method, and blood volume was measured by means of the {sup 15}O-labeled carbon monoxide bolus inhalation method. Blood flow was 1.68-6.47 ml/min/100 g (mean {+-}SD: 3.52{+-}1.2), and blood volume was 1.67-6.03 ml/100 g (mean {+-}SD: 3.00{+-}1.27). Blood flow significantly decreased (p<0.01) with age, and blood volume significantly increased (P<0.05). PET was useful in the measurement of blood flow and blood volume in the femoral heads. With age, physiological hemodynamic changes also increased in femoral heads. (author)
Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume II. Chapters 6-10)
Energy Technology Data Exchange (ETDEWEB)
Guo, T.; Park, J.; Kojasoy, G.
2003-03-15
Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.
Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume III. Chapters 11-14)
Energy Technology Data Exchange (ETDEWEB)
Guo, T.; Park, J.; Kojasoy, G.
2003-03-15
Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.
Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume IV. Chapters 15-19)
Energy Technology Data Exchange (ETDEWEB)
Guo, T.; Park, J.; Kojasoy, G.
2003-03-15
Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.
Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume I. Chapters 1-5)
Energy Technology Data Exchange (ETDEWEB)
Guo, T.; Park, J.; Kojasoy, G.
2003-03-15
Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.
A solution of two-dimensional magnetohydrodynamic flow using the finite volume method
Directory of Open Access Journals (Sweden)
Naceur Sonia
2014-01-01
Full Text Available This paper presents the two dimensional numerical modeling of the coupling electromagnetic-hydrodynamic phenomena in a conduction MHD pump using the Finite volume Method. Magnetohydrodynamic problems are, thus, interdisciplinary and coupled, since the effect of the velocity field appears in the magnetic transport equations, and the interaction between the electric current and the magnetic field appears in the momentum transport equations. The resolution of the Maxwell's and Navier Stokes equations is obtained by introducing the magnetic vector potential A, the vorticity z and the stream function y. The flux density, the electromagnetic force, and the velocity are graphically presented. Also, the simulation results agree with those obtained by Ansys Workbench Fluent software.
Recurrence-time statistics in non-Hamiltonian volume preserving maps and flows
da Silva, Rafael M; Manchein, Cesar
2015-01-01
We analyze the recurrence-time statistics (RTS) in three-dimensional non-Hamiltonian volume preserving systems (VPS): an extended standard map, and a fluid model. The extended map is a standard map weakly coupled to an extra-dimension which contains a deterministic regular, mixed (regular and chaotic) or chaotic motion. The extra-dimension strongly enhances the trapping times inducing plateaus and distinct algebraic and exponential decays in the RTS plots. The combined analysis of the RTS with the classification of ordered and chaotic regimes and scaling properties, allows us to describe the intricate way trajectories penetrate the before impenetrable regular islands from the uncoupled case. Essentially the plateaus found in the RTS are related to trajectories that stay long times inside trapping tubes, not allowing recurrences, and then penetrates diffusively the islands (from the uncoupled case) by a diffusive motion along such tubes in the extra-dimension. All asymptotic exponential decays for the RTS are ...
Stevens, Michael R.; Flynn, Jennifer L.; Stephens, Verlin C.; Verdin, Kristine L.
2011-01-01
During 2009, the U.S. Geological Survey, in cooperation with Gunnison County, initiated a study to estimate the potential for postwildfire debris flows to occur in the drainage basins occupied by Carbonate, Slate, Raspberry, and Milton Creeks near Marble, Colorado. Currently (2010), these drainage basins are unburned but could be burned by a future wildfire. Empirical models derived from statistical evaluation of data collected from recently burned basins throughout the intermountain western United States were used to estimate the probability of postwildfire debris-flow occurrence and debris-flow volumes for drainage basins occupied by Carbonate, Slate, Raspberry, and Milton Creeks near Marble. Data for the postwildfire debris-flow models included drainage basin area; area burned and burn severity; percentage of burned area; soil properties; rainfall total and intensity for the 5- and 25-year-recurrence, 1-hour-duration-rainfall; and topographic and soil property characteristics of the drainage basins occupied by the four creeks. A quasi-two-dimensional floodplain computer model (FLO-2D) was used to estimate the spatial distribution and the maximum instantaneous depth of the postwildfire debris-flow material during debris flow on the existing debris-flow fans that issue from the outlets of the four major drainage basins. The postwildfire debris-flow probabilities at the outlet of each drainage basin range from 1 to 19 percent for the 5-year-recurrence, 1-hour-duration rainfall, and from 3 to 35 percent for 25-year-recurrence, 1-hour-duration rainfall. The largest probabilities for postwildfire debris flow are estimated for Raspberry Creek (19 and 35 percent), whereas estimated debris-flow probabilities for the three other creeks range from 1 to 6 percent. The estimated postwildfire debris-flow volumes at the outlet of each creek range from 7,500 to 101,000 cubic meters for the 5-year-recurrence, 1-hour-duration rainfall, and from 9,400 to 126,000 cubic meters for
DEFF Research Database (Denmark)
Østergaard, Leif; Smith, D F; Vestergaard-Poulsen, Peter;
1998-01-01
The authors determined cerebral blood flow (CBF) with magnetic resonance imaging (MRI) of contrast agent bolus passage and compared the results with those obtained by O-15 labeled water (H215O) and positron emission tomography (PET). Six pigs were examined by MRI and PET under normo......- and hypercapnic conditions. After dose normalization and introduction of an empirical constant phi Gd, absolute regional CBF was calculated from MRI. The spatial resolution and the signal-to-noise ratio of CBF measurements by MRI were better than by the H215O-PET protocol. Magnetic resonance imaging cerebral...... blood volume (CBV) estimates obtained using this normalization constant correlated well with values obtained by O-15 labeled carbonmonooxide (C15O) PET. However, PET CBV values were approximately 2.5 times larger than absolute MRI CBV values, supporting the hypothesized sensitivity of MRI to small...
LENUS (Irish Health Repository)
King, Thomas F J
2013-01-01
Offspring birthweight is inversely associated with future maternal cardiovascular mortality, a relationship that has yet to be fully elucidated. Endothelial progenitor cells (EPCs) are thought to play a key role in vasculogenesis, and EPC numbers reflect cardiovascular risk.
National Research Council Canada - National Science Library
Collingwood Bakeo, Aleks; Clarke, Lynda
2006-01-01
This study examines whether there are socio-demographic factors (collected at census) that are not routinely available at birth registration that help to explain low birthweight in England and Wales in the 1980s and 1990s...
High-temperature, large-volume, lavalike ash-flow tuffs without calderas in southwestern Idaho
Ekren, E.B.; McIntyre, David H.; Bennett, Earl H.
1984-01-01
Rhyolitic rocks were erupted from vents in and adjacent to the Owyhee Mountains and Owyhee Plateau of southwestern Idaho from 16 m.y. ago to about 10 m.y. ago. They were deposited on a highly irregular surface developed on a variety of basement rocks that include granitic rocks of Cretaceous age, quartz latite and rhyodacite tuffs and lava flows of Eocene age, andesitic and basaltic lava flows of Oligocene age, and latitic and basaltic lava flows of early Miocene age. The rhyolitic rocks are principally welded tuffs that, regardless of their source, have one feature in common-namely internal characteristics indicating en-masse, viscous lavalike flowage. The flowage features commonly include considerable thicknesses of flow breccia at the bases of various cooling units. On the basis of the tabular nature of the rhyolitic deposits, their broad areal extents, and the local preservation of pyroclastic textures at the bases, tops, and distal ends of some of the deposits, we have concluded that the rocks were emplaced as ash flows at extremely high temperatures and that they coalesced to liquids before final emplacement and cooling. Temperatures of l090?C and higher are indicated by iron-titanium oxide compositions. Rhyolites that are about 16 m.y. old are preserved mostly in the downdropped eastern and western flanks of the Silver City Range and they are inferred to have been erupted from the Silver City Range. They rarely contain more than about 2 percent phenocrysts that consist of quartz and subequal amounts of plagioclase and alkali feldspar; commonly, they contain biotite, and they are the only rhyolitic rocks in the area to do so. The several rhyolitic units that are 14 m.y. to about 10 m.y. old contain only pyroxene-principally ferriferous and intermediate pigeonites-as mafic constituents. The rhyolites of the Silver City Range comprise many cooling units, none of which can be traced for great distances. Rocks erupted from the Owyhee Plateau include two sequences
Directory of Open Access Journals (Sweden)
Cordola Giorgio
2007-02-01
Full Text Available Abstract Background The aims of this study were to verify the feasibility of respiratory function tests and to assess their validity in the diagnosis of respiratory disorders in young children. Methods We performed spirometry and collected information on health and parents' lifestyle on a sample of 960 children aged 3–6. Results The cooperation rate was 95.3%. Among the valid tests, 3 or more acceptable curves were present in 93% of cases. The variability was 5% within subjects in 90.8% of cases in all the parameters. We propose regression equations for FVC (Forced Vital Capacity, FEV1, FEV0.5, FEV0.75 (Forced Expiratory Volume in one second, in half a second and in 3/4 of a second, and for Maximum Expiratory Flows at different lung volume levels (MEF75, 50, 25. All parameters are consistent with the main reference values reported in literature. The discriminating ability of respiratory parameters versus symptoms always shows a high specificity (>95% and a low sensitivity ( Conclusion Our study confirms the feasibility of spirometry in young children; however some of the current standards are not well suited to this age group. Moreover, in this restricted age group the various reference values have similar behaviour.
Optical flow based deformable volume registration using a novel second-order regularization prior
Grbić, Saša; Urschler, Martin; Pock, Thomas; Bischof, Horst
2010-03-01
Nonlinear image registration is an initial step for a large number of medical image analysis applications. Optical flow based intensity registration is often used for dealing with intra-modality applications involving motion differences. In this work we present an energy functional which uses a novel, second-order regularization prior of the displacement field. Compared to other methods our scheme is robust to non-Gaussian noise and does not penalize locally affine deformation fields in homogeneous areas. We propose an efficient and stable numerical scheme to find the minimizer of the presented energy. We implemented our algorithm using modern consumer graphics processing units and thereby increased the execution performance dramatically. We further show experimental evaluations on clinical CT thorax data sets at different breathing states and on dynamic 4D CT cardiac data sets.
Fowlie, P; Tarnow-Mordi, W; Gould, C.; Strang, D
1998-01-01
AIM—To investigate the feasibility of developing an objective tool for predicting death and severe disability using routinely available data, including an objective measure of illness severity, in very low birthweight babies. METHOD—A cohort study of 297 premature babies surviving the first three days of life was made. Predictive variables considered included birthweight, gestation, 3 day cranial ultrasound appearances and 3 day CRIB (clinical risk index for babies) score. ...
Institute of Scientific and Technical Information of China (English)
ZHANG Lian-yang; ZHAO Song; LI Yong; MA Xiao-lin
2009-01-01
Objective: To investigate the effects of CO2 pneumo-peritoneum on blood flow volume of abdominal organs of rabbits with controlled hemorrhagic shock model and liver impact injuries.Methods: After controlled hemorrhagic shock and liver impact injuries, the rabbit model was established. Eighteen rabbits subjected to hemorrhagic shock and liver impact inju-ries were divided into 3 groups randomly according to the volume of lost blood: light hemorrhagic shock (blood loss volume was 10%, 6 ml/kg), moderate hemorrhagic shock (20%, 12 ml/kg) and severe hemorrhagic shock (40%, 22 ml/kg). Intraabdominal pressures of CO2 pneumoperitoneum was 10 mmHg. Color-labeled microspheres were used to mea-sure the blood flow volume of the liver, kidney and stomach before pneumoperitoneum at 30 minutes and 2 hours after pneumoperitoneum and 30 minutes after deflation. And the mortality and hepatic traumatic condition of rabbits were recorded.Results: Of the 18 rabbits, there were 9 with liver impact injuries at Grade Ⅰ, 8 at Grade Ⅱ and Ⅰ at Grade Ⅲ (according to AIS-2005). The mortality rate in light hemorrhagic shock group was 33.33%, and that in moderate or severe hemor-rhagic shock group was 100% within 30 minutes and 2 hours after pneumoperitoneum, respectively. The blood flow vol-ume in the organs detected decreased at 30 minutes under pneumoperitoneum in light and moderate hemorrhagic shock groups. At the same time, the blood flow volume of the liver in moderate hemorrhagic shock group decreased more sig-nificantly than that in light hemorrhagic shock group.Conclusions: The blood flow volume of abdominal organs in rabbits is decreased obviously under CO2 pneumoperitoneum, with fairly high mortality rate. It is be-lieved that CO2 pneumoperitoneum should cautiously be used in abdominal injury accompanied with hemorrhagic shock, especially under non-resuscitation conditions.
Directory of Open Access Journals (Sweden)
Gopala Krishna Alaparthi
2016-01-01
Full Text Available Objective. To evaluate the effects of diaphragmatic breathing exercises and flow and volume-oriented incentive spirometry on pulmonary function and diaphragm excursion in patients undergoing laparoscopic abdominal surgery. Methodology. We selected 260 patients posted for laparoscopic abdominal surgery and they were block randomization as follows: 65 patients performed diaphragmatic breathing exercises, 65 patients performed flow incentive spirometry, 65 patients performed volume incentive spirometry, and 65 patients participated as a control group. All of them underwent evaluation of pulmonary function with measurement of Forced Vital Capacity (FVC, Forced Expiratory Volume in the first second (FEV1, Peak Expiratory Flow Rate (PEFR, and diaphragm excursion measurement by ultrasonography before the operation and on the first and second postoperative days. With the level of significance set at p<0.05. Results. Pulmonary function and diaphragm excursion showed a significant decrease on the first postoperative day in all four groups (p<0.001 but was evident more in the control group than in the experimental groups. On the second postoperative day pulmonary function (Forced Vital Capacity and diaphragm excursion were found to be better preserved in volume incentive spirometry and diaphragmatic breathing exercise group than in the flow incentive spirometry group and the control group. Pulmonary function (Forced Vital Capacity and diaphragm excursion showed statistically significant differences between volume incentive spirometry and diaphragmatic breathing exercise group (p<0.05 as compared to that flow incentive spirometry group and the control group. Conclusion. Volume incentive spirometry and diaphragmatic breathing exercise can be recommended as an intervention for all patients pre- and postoperatively, over flow-oriented incentive spirometry for the generation and sustenance of pulmonary function and diaphragm excursion in the management of
Recurrence-time statistics in non-Hamiltonian volume-preserving maps and flows
da Silva, Rafael M.; Beims, Marcus W.; Manchein, Cesar
2015-08-01
We analyze the recurrence-time statistics (RTS) in three-dimensional non-Hamiltonian volume-preserving systems (VPS): an extended standard map and a fluid model. The extended map is a standard map weakly coupled to an extra dimension which contains a deterministic regular, mixed (regular and chaotic), or chaotic motion. The extra dimension strongly enhances the trapping times inducing plateaus and distinct algebraic and exponential decays in the RTS plots. The combined analysis of the RTS with the classification of ordered and chaotic regimes and scaling properties allows us to describe the intricate way trajectories penetrate the previously impenetrable regular islands from the uncoupled case. Essentially the plateaus found in the RTS are related to trajectories that stay for long times inside trapping tubes, not allowing recurrences, and then penetrate diffusively the islands (from the uncoupled case) by a diffusive motion along such tubes in the extra dimension. All asymptotic exponential decays for the RTS are related to an ordered regime (quasiregular motion), and a mixing dynamics is conjectured for the model. These results are compared to the RTS of the standard map with dissipation or noise, showing the peculiarities obtained by using three-dimensional VPS. We also analyze the RTS for a fluid model and show remarkable similarities to the RTS in the extended standard map problem.
Acu-TENS and Postexercise Expiratory Flow Volume in Healthy Subjects
Directory of Open Access Journals (Sweden)
Shirley P. C. Ngai
2011-01-01
Full Text Available Transcutaneous Electrical Nerve Stimulation over acupoints (Acu-TENS facilitates recovery of resting heart rate after treadmill exercise in healthy subjects. Its effect on postexercise respiratory indices has not been reported. This study investigates the effect of Acu-TENS on forced expiratory volume in 1 second (FEV1 and forced vital capacity (FVC in healthy subjects after a submaximal exercise. Eleven male subjects were invited to the laboratory twice, two weeks apart, to receive in random order either Acu-TENS or Placebo-TENS (no electrical output from the TENS unit over bilateral Lieque (LU7 and Dingchuan (EX-B1 for 45 minutes, before undergoing exercise following the Bruce protocol. Exercise duration, rate of perceived exertion (RPE, and peak heart rate (PHR were recorded. Between-group FEV1 and FVC, before, immediately after, at 15, 30, and 45minutes postexercise, were compared. While no between-group differences in PHR, RPE, and FVC were found, Acu-TENS was associated with a longer exercise duration (0.9 min (P=.026 and a higher percentage increase in FEV1 at 15 and 45 minutes postexercise (3.3 ± 3.7% (P=.013 and 5.1 ± 7.5% (P=.047, resp. compared to Placebo-TENS. We concluded that Acu-TENS was associated with a higher postexercise FEV1 and a prolongation of submaximal exercise.
Analysis of triangular C-grid finite volume scheme for shallow water flows
Shirkhani, Hamidreza; Mohammadian, Abdolmajid; Seidou, Ousmane; Qiblawey, Hazim
2015-08-01
In this paper, a dispersion relation analysis is employed to investigate the finite volume triangular C-grid formulation for two-dimensional shallow-water equations. In addition, two proposed combinations of time-stepping methods with the C-grid spatial discretization are investigated. In the first part of this study, the C-grid spatial discretization scheme is assessed, and in the second part, fully discrete schemes are analyzed. Analysis of the semi-discretized scheme (i.e. only spatial discretization) shows that there is no damping associated with the spatial C-grid scheme, and its phase speed behavior is also acceptable for long and intermediate waves. The analytical dispersion analysis after considering the effect of time discretization shows that the Leap-Frog time stepping technique can improve the phase speed behavior of the numerical method; however it could not damp the shorter decelerated waves. The Adams-Bashforth technique leads to slower propagation of short and intermediate waves and it damps those waves with a slower propagating speed. The numerical solutions of various test problems also conform and are in good agreement with the analytical dispersion analysis. They also indicate that the Adams-Bashforth scheme exhibits faster convergence and more accurate results, respectively, when the spatial and temporal step size decreases. However, the Leap-Frog scheme is more stable with higher CFL numbers.
Seymour, Roger S.; Bosiocic, Vanya; Snelling, Edward P.
2016-08-01
The evolution of human cognition has been inferred from anthropological discoveries and estimates of brain size from fossil skulls. A more direct measure of cognition would be cerebral metabolic rate, which is proportional to cerebral blood flow rate (perfusion). The hominin cerebrum is supplied almost exclusively by the internal carotid arteries. The sizes of the foramina that transmitted these vessels in life can be measured in hominin fossil skulls and used to calculate cerebral perfusion rate. Perfusion in 11 species of hominin ancestors, from Australopithecus to archaic Homo sapiens, increases disproportionately when scaled against brain volume (the allometric exponent is 1.41). The high exponent indicates an increase in the metabolic intensity of cerebral tissue in later Homo species, rather than remaining constant (1.0) as expected by a linear increase in neuron number, or decreasing according to Kleiber's Law (0.75). During 3 Myr of hominin evolution, cerebral tissue perfusion increased 1.7-fold, which, when multiplied by a 3.5-fold increase in brain size, indicates a 6.0-fold increase in total cerebral blood flow rate. This is probably associated with increased interneuron connectivity, synaptic activity and cognitive function, which all ultimately depend on cerebral metabolic rate.
Loh, Ching Y.; Jorgenson, Philip C. E.
2007-01-01
A time-accurate, upwind, finite volume method for computing compressible flows on unstructured grids is presented. The method is second order accurate in space and time and yields high resolution in the presence of discontinuities. For efficiency, the Roe approximate Riemann solver with an entropy correction is employed. In the basic Euler/Navier-Stokes scheme, many concepts of high order upwind schemes are adopted: the surface flux integrals are carefully treated, a Cauchy-Kowalewski time-stepping scheme is used in the time-marching stage, and a multidimensional limiter is applied in the reconstruction stage. However even with these up-to-date improvements, the basic upwind scheme is still plagued by the so-called "pathological behaviors," e.g., the carbuncle phenomenon, the expansion shock, etc. A solution to these limitations is presented which uses a very simple dissipation model while still preserving second order accuracy. This scheme is referred to as the enhanced time-accurate upwind (ETAU) scheme in this paper. The unstructured grid capability renders flexibility for use in complex geometry; and the present ETAU Euler/Navier-Stokes scheme is capable of handling a broad spectrum of flow regimes from high supersonic to subsonic at very low Mach number, appropriate for both CFD (computational fluid dynamics) and CAA (computational aeroacoustics). Numerous examples are included to demonstrate the robustness of the methods.
Česenek, Jan
The article is concerned with the numerical simulation of the compressible turbulent flow in time dependent domains. The mathematical model of flow is represented by the system of non-stationary Reynolds- Averaged Navier-Stokes (RANS) equations. The motion of the domain occupied by the fluid is taken into account with the aid of the ALE (Arbitrary Lagrangian-Eulerian) formulation of the RANS equations. This RANS system is equipped with two-equation k - ω turbulence model. These two systems of equations are solved separately. Discretization of the RANS system is carried out by the space-time discontinuous Galerkin method which is based on piecewise polynomial discontinuous approximation of the sought solution in space and in time. Discretization of the two-equation k - ω turbulence model is carried out by the implicit finite volume method, which is based on piecewise constant approximation of the sought solution. We present some numerical experiments to demonstrate the applicability of the method using own-developed code.
A data-driven approach for modeling post-fire debris-flow volumes and their uncertainty
Friedel, M.J.
2011-01-01
This study demonstrates the novel application of genetic programming to evolve nonlinear post-fire debris-flow volume equations from variables associated with a data-driven conceptual model of the western United States. The search space is constrained using a multi-component objective function that simultaneously minimizes root-mean squared and unit errors for the evolution of fittest equations. An optimization technique is then used to estimate the limits of nonlinear prediction uncertainty associated with the debris-flow equations. In contrast to a published multiple linear regression three-variable equation, linking basin area with slopes greater or equal to 30 percent, burn severity characterized as area burned moderate plus high, and total storm rainfall, the data-driven approach discovers many nonlinear and several dimensionally consistent equations that are unbiased and have less prediction uncertainty. Of the nonlinear equations, the best performance (lowest prediction uncertainty) is achieved when using three variables: average basin slope, total burned area, and total storm rainfall. Further reduction in uncertainty is possible for the nonlinear equations when dimensional consistency is not a priority and by subsequently applying a gradient solver to the fittest solutions. The data-driven modeling approach can be applied to nonlinear multivariate problems in all fields of study. ?? 2011.
Directory of Open Access Journals (Sweden)
Reiher Horst
2002-06-01
Full Text Available Abstract Background Very low birthweight, i.e. a birthweight Methods In 1992, two years after the German unification, we started to recruit two cohorts of very low birthweight infants and controls in East and West Berlin for a long-term neurodevelopmental study. The present analysis was undertaken to compare potential preconceptional risk factors for very low birthweight delivery in a case-control design including 166 mothers (82 East vs. 84 West Berlin with very low birthweight delivery and 341 control mothers (166 East vs. 175 West. Results Multivariate logistic regression analysis was used to assess the effects of various dichotomous parental covariates and their interaction with living in East or West Berlin. After backward variable selection, short maternal school education, maternal unemployment, single-room apartment, smoking, previous preterm delivery, and fetal loss emerged as significant main effect variables, together with living in West Berlin as positive effect modificator for single-mother status. Conclusion Very low birthweight has been differentially associated with obstetrical history and indicators of maternal socioeconomic status in East and West Berlin. The ranking of these risk factors is under the influence of the political framework.
King, Thomas F J; Bergin, David A; Kent, Etaoin M; Manning, Fiona; Reeves, Emer P; Dicker, Patrick; McElvaney, Noel G; Sreenan, Seamus; Malone, Fergal D; McDermott, John H
2013-01-01
Offspring birthweight is inversely associated with future maternal cardiovascular mortality, a relationship that has yet to be fully elucidated. Endothelial progenitor cells (EPCs) are thought to play a key role in vasculogenesis, and EPC numbers reflect cardiovascular risk. Our objective was to ascertain whether EPC number or function was reduced in mothers of low-birthweight infants. This was a prospective cohort study in a general antenatal department of a university maternity hospital. Twenty-three mothers of small for gestational age (SGA) infants (birthweight mothers of appropriate for gestational age (AGA) infants (birthweight ≥ 10th centile) were recruited. Maternal EPC number and function, conventional cardiovascular risk markers, and cord blood adiponectin were measured. Median EPC count was lower (294 vs. 367, P = 0.005) and EPC migration was reduced (0.91 vs. 1.59, P < 0.001) in SGA compared with AGA infants, with no difference in EPC adhesion (0.221 vs. 0.284 fluorescence units, P = 0.257). Maternal triglyceride levels were higher in SGA than AGA infants (0.98 vs. 0.78 mmol/liter, P = 0.006), but there was no difference in cholesterol, glucose, insulin, glycosylated hemoglobin, adiponectin, or blood pressure. There was a moderate monotone (increasing) relationship between birthweight and umbilical cord blood adiponectin (r = 0.475, P = 0.005). Giving birth to an SGA infant was associated with lower maternal EPC number and reduced migratory function. Cord blood adiponectin was significantly correlated with birthweight.
Single motherhood and low birthweight in Spain: Narrowing social inequalities in health?
Directory of Open Access Journals (Sweden)
Teresa Castro-Martin
2010-05-01
Full Text Available Nonmarital childbearing is becoming an increasingly common path to family formation in Spain. The proportion of births to unmarried mothers has increased from 2Š in 1975 to 30.2Š in 2007. Along with this marked increase, there has been an important shift in the sociodemographic profile of unmarried mothers. This study focuses on the impact of mothers' marital status on the health status of their newborns, using low birthweight as an indicator. We are interested in examining how the impact of mothers' unmarried status on birth outcomes changes as nonmarital childbearing shifts from a marginal to a relatively common behaviour. The results of the analysis reveal that the health disadvantage gap between marital and nonmarital births has narrowed significantly over the past decade in Spain. We argue that diminishing selection processes and increasing social acceptance could explain the declining significance of marital status as a risk factor for low birthweight.
Vitamin A supplementation and BCG vaccination at birth in low birthweight neonates
DEFF Research Database (Denmark)
Benn, Christine Stabell; Fisker, Ane Baerent; Napirna, Bitiguida Mutna
2010-01-01
OBJECTIVE: To investigate the effect of vitamin A supplementation and BCG vaccination at birth in low birthweight neonates. DESIGN: Randomised, placebo controlled, two by two factorial trial. SETTING: Bissau, Guinea-Bissau. PARTICIPANTS: 1717 low birthweight neonates born at the national hospital....... INTERVENTION: Neonates who weighed less than 2.5 kg were randomly assigned to 25 000 IU vitamin A or placebo, as well as to early BCG vaccine or the usual late BCG vaccine, and were followed until age 12 months. MAIN OUTCOME MEASURE: Mortality, calculated as mortality rate ratios (MRRs), after follow-up to 12...... months of age for infants who received vitamin A supplementation compared with those who received placebo. RESULTS: No interaction was observed between vitamin A supplementation and BCG vaccine allocation (P=0.73). Vitamin A supplementation at birth was not significantly associated with mortality...
Salama, Amgad
2013-09-01
In this work the problem of flow in three-dimensional, axisymmetric, heterogeneous porous medium domain is investigated numerically. For this system, it is natural to use cylindrical coordinate system, which is useful in describing phenomena that have some rotational symmetry about the longitudinal axis. This can happen in porous media, for example, in the vicinity of production/injection wells. The basic feature of this system is the fact that the flux component (volume flow rate per unit area) in the radial direction is changing because of the continuous change of the area. In this case, variables change rapidly closer to the axis of symmetry and this requires the mesh to be denser. In this work, we generalize a methodology that allows coarser mesh to be used and yet yields accurate results. This method is based on constructing local analytical solution in each cell in the radial direction and moves the derivatives in the other directions to the source term. A new expression for the harmonic mean of the hydraulic conductivity in the radial direction is developed. Apparently, this approach conforms to the analytical solution for uni-directional flows in radial direction in homogeneous porous media. For the case when the porous medium is heterogeneous or the boundary conditions is more complex, comparing with the mesh-independent solution, this approach requires only coarser mesh to arrive at this solution while the traditional methods require more denser mesh. Comparisons for different hydraulic conductivity scenarios and boundary conditions have also been introduced. © 2013 Elsevier B.V.
Innovative cross-flow membrane system for volume reduction of mixed waste
Energy Technology Data Exchange (ETDEWEB)
Greene, W. [SpinTek Membrane Systems, Huntington Beach, CA (United States)
1997-10-01
In this task, SpinTek Membrane Systems, Inc., and the Institute of Gas Technology are completing engineering development leading to a full-scale demonstration of the SpinTek ST-II High Shear Rotary Membrane Filtration System (ST-II) under a Program Research and Development Agreement (PRDA) with the Federal Energy Technology Center-Morgantown. The SpinTek ST-II technology will be scaled-up, and a two-stage ST-II system will be designed, constructed, and operated on both surrogate and actual feed at the Los Alamos National Laboratory (LANL) Liquid Radioactive Waste Treatment Facility (LRWTF). Results from these studies on both surrogate and actual wastewater streams will also be used by LANL personnel to produce a model for determining the applicability and economics of the SpinTek ST-II system to other DOE waste and process streams. The ST-II is a unique, compact cross-flow membrane system having several advantages in performance and cost compared to currently available systems. Staff at LANL have performed pilot-scale testing with the SpinTek technology to evaluate its feasibility for enhanced radionuclide removal from wastewater at its 5- to 8-million-gallon-per-year LRWTF. Recent data have shown the system`s capabilities to remove radionuclides from the waste stream at concentration factors greater than 2000:1, and performance has exceeded both conventional and all other advanced technologies examined.
SRM Internal Flow Test and Computational Fluid Dynamic Analysis. Volume 1; Major Task Summaries
Whitesides, R. Harold; Dill, Richard A.; Purinton, David C.
1995-01-01
During the four year period of performance for NASA contract, NASB-39095, ERC has performed a wide variety of tasks to support the design and continued development of new and existing solid rocket motors and the resolution of operational problems associated with existing solid rocket motor's at NASA MSFC. This report summarizes the support provided to NASA MSFC during the contractual period of performance. The report is divided into three main sections. The first section presents summaries for the major tasks performed. These tasks are grouped into three major categories: full scale motor analysis, subscale motor analysis and cold flow analysis. The second section includes summaries describing the computational fluid dynamics (CFD) tasks performed. The third section, the appendices of the report, presents detailed descriptions of the analysis efforts as well as published papers, memoranda and final reports associated with specific tasks. These appendices are referenced in the summaries. The subsection numbers for the three sections correspond to the same topics for direct cross referencing.
Does consumption of different categories of seafood affect birthweight? The HUMIS study
Energy Technology Data Exchange (ETDEWEB)
Fristad, R.F.; Eggesboe, M.; Stigum, H.; Magnus, P. [Norwegian Inst. of Public Health, Oslo (Norway)
2004-09-15
Seafood is an important part of a healthy diet. Polyunsaturated fatty acids present in seafood play an essential role in the development of the central nervous system, of special importance to the brain development. The long chain n-3 fatty acids have also been reported to increase gestational length. Fish intake during pregnancy has been associated with both increased birthweight and gestational length. Birthweight is considered to be a predictor of a number of disorders in infant and adult life. However, negative effects may arise in connection with fish and shellfish intake. Seafood can be a major source of environmental contaminants, and correspondingly, adverse effects on pregnancy outcomes have been reported. In contrast, in a publication review carried out on the relationship between PCBs and related chemicals on several pregnancy outcomes, Kimbrough and Krouskas claim that none of the reviewed studies provided evidence on the existence of adverse effects on birthweight. Distinction between consumption of different types of seafood and its relation to pregnancy outcomes is scarce in the literature. Since the source of environmental contaminants is mainly in the marine fat, and that fat content potentially differ in the various categories of seafood items, it is plausible that different categories of seafood may have distinct health effects on fetal growth and gestational length. The objective of this study was to investigate the consumption of three major categories of seafood (fatty fish, lean/half-fatty fish and shellfish), potentially differing in their content of environmental toxicants, and its effects on pregnancy outcomes, specifically, birthweight and gestational length.
Comparison of mortality risk: a score for very low birthweight infants
Maier, R; Rey, M; Metze, B; Obladen;, M; TARNOW-MORDI, W.
1997-01-01
AIM—To develop and evaluate a score which quantifies mortality risk in very low birthweight (VLBW) infants (birthweight below 1500 g) at admission to the neonatal intensive care unit. METHODS—Five hundred and seventy two VLBW infants admitted from 1978 to 1987 were randomly assigned to a cohort (n = 396) for score development and a cohort (n = 176) for score validation. Two hundred and ninety four VLBW infants admitted from 1988 to 1991 were used to compare risk adjusted mortality between the two eras. RESULTS—Using multiple regression analysis, birthweight, Apgar score at 5 minutes, base excess at admission, severity of respiratory distress syndrome, and artificial ventilation were predictive of death in the development cohort. According to regression coefficients, a score ranging from 3 to 40 was developed. At a cutoff of 21, it predicted death in the validation cohort with a sensitivity of 0.85, a specificity of 0.73, and a correct classification rate of 0.76. The area under the receiver operating characteristic curve was 0.86. There was no significant difference in risk severity and in risk adjusted mortality between the eras 1978-87 and 1988-91. CONCLUSION—The present score is robust, easily obtainable at admission, and permits early randomisation based on mortality risk. Keywords: mortality risk; scoring system; very low birthweight PMID:9175942
Birthweight, maternal weight trajectories and global DNA methylation of LINE-1 repetitive elements.
Directory of Open Access Journals (Sweden)
Karin B Michels
Full Text Available Low birthweight, premature birth, intrauterine growth retardation, and maternal malnutrition have been related to an increased risk of cardiovascular disease, type 2 diabetes mellitus, obesity, and neuropsychiatric disorders later in life. Conversely, high birthweight has been linked to future risk of cancer. Global DNA methylation estimated by the methylation of repetitive sequences in the genome is an indicator of susceptibility to chronic diseases. We used data and biospecimens from an epigenetic birth cohort to explore the association between trajectories of fetal and maternal weight and LINE-1 methylation in 319 mother-child dyads. Newborns with low or high birthweight had significantly lower LINE-1 methylation levels in their cord blood compared to normal weight infants after adjusting for gestational age, sex of the child, maternal age at delivery, and maternal smoking during pregnancy (p = 0.007 and p = 0.036, respectively, but the magnitude of the difference was small. Infants born prematurely also had lower LINE-1 methylation levels in cord blood compared to term infants, and this difference, though small, was statistically significant (p = 0.004. We did not find important associations between maternal prepregnancy BMI or gestational weight gain and global methylation of the cord blood or fetal placental tissue. In conclusion, we found significant differences in cord blood LINE-1 methylation among newborns with low and high birthweight as well as among prematurely born infants. Future studies may elucidate whether chromosomal instabilities or other functional consequences of these changes contribute to the increased risk of chronic diseases among individuals with these characteristics.
DEFF Research Database (Denmark)
Bonnesen, Barbara; Oddgeirsdóttir, Hanna L; Naver, Klara Vinsand
2016-01-01
examination-based gestational age. Outcome measures were gestational diabetes, hypertension, preeclampsia, preterm premature rupture of membranes, preterm birth, prolonged pregnancy, birthweight, umbilical artery pH ... with more than 7 days' deviation between self-reported and ultrasound examination-based gestational age were compared with women with a deviation of 7 days or less. RESULTS: Irregular menstrual cycle before conception increases the risk of preeclampsia (7.9% vs. 5.2%, p
Extreme macrosomia--obstetric outcomes and complications in birthweights >5000 g.
Hehir, Mark P; Mchugh, Ann F; Maguire, Patrick J; Mahony, Rhona
2015-02-01
Management of extremely large birthweight infants presents challenges during the period of labour and delivery. We sought to examine outcomes in infants with extreme macrosomia (birthweight > 5000 g), at an institution where the management of labour is standardised. This is a retrospective analysis of prospectively gathered data on all infants with a birthweight >5000 g delivered at a tertiary level institution from 2008 to 2012. Details of labour characteristics and outcomes were examined; these were compared according to parity. During the study period, there were 46 128 deliveries at the hospital and 182 infants with a birthweight >5000 g, giving an incidence of 0.4%. The majority of women (133/182) were multiparous. Among nulliparas, 47% (23/49) had a vaginal delivery, while 53% (26/49) had a caesarean delivery. 86% (97/113) of multiparas had a vaginal delivery, and 14% (16/113) had a caesarean delivery. 43% (69/162) required induction of labour. This was more common in nulliparous compared with multiparous women (58% [29/49] vs 30% [40/133], P = 0.005, OR = 3.4, 95% CI = 1.7-6.6). A total of 30% (49/162) of women had their labour accelerated with oxytocin. There were higher rates of oxytocin use in nulliparas than in multiparas (55% [27/49] vs 16.5% [22/133], P macrosomia affects 0.4% of pregnancies in contemporary practice. Multiparas have a low rate of caesarean section. Infants delivered vaginally are at increased risk of shoulder dystocia and associated complications. © 2015 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.
The influence on birthweight of maternal living conditions a decade prior to giving birth
Directory of Open Access Journals (Sweden)
John Singhammer
2009-10-01
Full Text Available The study’s aim was to correlate measures of mothers’ socio-economic status, a decade prior to giving birth, with their children’s birthweight. As part of a larger study, information on birth characteristics from 706 babies born 1970-73 were linked with census data obtained from their mothers near the time of birth as well as one decade earlier. The 706 individuals were selected at random from two national surveys in 1998 and 2000 and traced back to the time of birth in the period 1970-73. Information on birth characteristics was linked to census data obtained from the mothers in 1960 and 1970. Included was information on parent’s living conditions (e.g. income, type of dwelling, indoor plumbing, telephone, number of people in the household. Information on mother’s health during pregnancy, a decade before childbirth and near childbirth, and data on mothers’ and the infants’ health at birth was obtained from the Medical Birth Registry of Norway. In analysis that included both early and current socio-economic conditions maternal education and rural residency at the time of giving birth were observed as statistical significant predictors of birthweight. Results were adjusted for maternal age, parity, plurality, gender and diagnoses before and during pregnancy, all factors observed to attenuate birthweight. Indicators of women’s socio-economic conditions a decade prior to giving birth were not significantly associated with birthweight. These findings do not clearly support suggestions in the literature that an infant’s vitality may be influenced by the family’s socio-economic conditions years before birth.
DEFF Research Database (Denmark)
Sander, Pia; Mouritsen, L; Andersen, J Thorup
2002-01-01
OBJECTIVE: The aim of this study was to evaluate the value of routine measurements of urinary flow rate and residual urine volume as a part of a "minimal care" assessment programme for women with urinary incontinence in detecting clinical significant bladder emptying problems. MATERIAL AND METHOD...... female urinary incontinence. Thus, primary health care providers can assess women based on simple guidelines without expensive equipment for assessment of urine flow rate and residual urine....
Results of temperature gradient and heat flow in Santiam Pass Area, Oregon, Volume 1
Energy Technology Data Exchange (ETDEWEB)
Cox, B.L.; Gardner, M.C.; Koenig, J.B.
1981-08-01
The conclusions of this report are: (1) There is a weakly defined thermal anomaly within the area examined by temperature-gradient holes in the Santiam Pass area. This is a relict anomaly showing differences in permeability between the High Cascades and Western Cascades areas, more than a fundamental difference in shallow crustal temperatures. (2) The anomaly as defined by the 60 F isotherms at 400 feet follows a north-south trend immediately westward of the Cascade axis in the boundary region. It is clear that all holes spudded into High Cascades rocks result in isothermal and reversal gradients. Holes spudded in Western Cascades rocks result in positive gradients. (3) Cold groundwater flow influences and masks temperature gradients in the High Cascades to a depth of at least 700 feet, especially eastward from the major north-south trending faults. Pleistocene and Holocene rocks are very permeable aquifers. (4) Shallow gradient drilling in the lowlands westward of the faults provides more interpretable information than shallow drilling in the cold-water recharge zones. Topographic and climatological effects can be filtered out of the temperature gradient results. (5) The thermal anomaly seems to have 2 centers: one in the Belknap-Foley area, and one northward in the Sand Mountain area. The anomalies may or may not be connected along a north-south trend. (6) A geothermal effect is seen in holes downslope of the Western-High Cascade boundary. Mixing with cold waters is a powerful influence on temperature gradient data. (7) The temperature-gradient program has not yet examined and defined the geothermal resources potential of the area eastward of the Western Cascades-High Cascades boundary. Holes to 1500-2000 feet in depth are required to penetrate the high permeability-cold groundwater regime. (8) Drilling conditions are unfavorable. There are very few accessible level drill sites. Seasonal access problems and environmental restrictions together with frequent lost
PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP (VOLUME 55) COLLECTIVE FLOW AND QGP PROPERTIES.
Energy Technology Data Exchange (ETDEWEB)
BASS,S.ESUMI,S.HEINZ,U.KOLB,P.SHURYAK,E.XU,N.
2003-11-17
The first three years of RHIC physics, with Au/Au collisions induced at 65, 130 and 200 GeV per nucleon pair, produced dramatic results, particularly with respect to collective observables such as transverse flow and anisotropies in transverse momentum spectra. It has become clear that the data show very strong rescattering at very early times of the reaction, strong enough in fact to be described by the hydrodynamic limit. Therefore, with today's experiments, we are able to investigate the equation of state of hot quark gluon matter, discuss its thermodynamic properties and relate them to experimental observables. At this workshop we came together to discuss our latest efforts both in the theoretical description of heavy ion collisions as well as most recent experimental results that ultimately allow us to extract information on the properties of RHIC matter. About 50 participants registered for the workshop, but many more dropped in from the offices at BNL. The workshop lasted for three days, of which each day was assigned a special topic on which the talks focused. On the first day we dealt with the more general question what the strong collective phenomena observed in RHIC collisions tell us about the properties and the dynamics of RHIC matter. The second day covered all different aspects of momentum anisotropies, and interesting new experimental results were presented for the first time. On the third day, we focused on the late fireball dynamics and the breakdown of the assumption of thermalization. New experimental observables were discussed, which will deliver more information of how the expanding fireball breaks up, once the frequent interaction ceases.
Factors related to transfusion in very low birthweight infants treated with erythropoietin.
Maier, R. F.; Obladen, M.; Messinger, D.; Wardrop, C. A.
1996-01-01
The need for red cell transfusions is reduced but not eliminated by recombinant human erythropoietin (rhEPO) in very low birthweight (VLBW) infants. To detect factors associated with the decision to transfuse VLBW infants during rhEPO treatment and to explain rhEPO 'non-responders', the subgroup of those 120 VLBW infants who were treated with rhEPO 750 IU/kg per week in the second European Multicentre rhEPO Trial was evaluated. Sixty (50%) infants received at least one transfusion during erythropoietin treatment. Transfusion was frequent in infants with extremely low birthweight (79% for 750-999 g), low gestational age (70% for or = 1 ml/kg per day). The prognostic variables birthweight, initial haematocrit, and gestational age were found to be most predictive for transfusion. To improve rhEPO response in VLBW infants, there is a need to minimise diagnostic blood loss, to prevent iron deficiency, and to develop rational criteria for transfusion in preterm infants. PMID:8777681
The mixed effects of migration: community-level migration and birthweight in Mexico.
Hamilton, Erin R; Choi, Kate H
2015-05-01
Research on the relationship between migration and infant health in Mexico finds that migration has mixed impacts on the risk of low birthweight (LBW). Whereas the departure and absence of household and community members are harmful, remittances are beneficial. We extend this work by considering a different measure of infant health in addition to LBW: macrosomia (i.e., heavy birthweight), which is associated with infant, child, and maternal morbidities but has a different social risk profile from LBW. We link the 2008 and 2009 Mexican birth certificates with community data from the 2000 Mexican census to analyze the association between various dimensions of community-level migration (i.e., rates of out-migration, receipt of remittances, and return migration) and the risk of LBW and macrosomia. We examine this association using two sets of models which differ in the extent to which they account for endogeneity. We find that the health impacts of migration differ depending not only on the dimension of migration, but also on the measure of health, and that they are robust to potential sources of endogeneity. Whereas community remittances and return migration are associated with lower risk of LBW, they are associated with increased risk of macrosomia. By contrast, out-migration is associated with increased risk of LBW and lower risk of macrosomia. Our analysis of endogeneity suggests that bias resulting from unmeasured differences between communities with different levels of migration may result in an underestimate of the impacts of community migration on birthweight.
Directory of Open Access Journals (Sweden)
Anna K. Poon
2013-01-01
Full Text Available Our analysis examined the impact of maternal dietary patterns and lifestyle factors on markers of fetal growth, specifically birthweight and size for gestational age (small- (SGA or large-for-gestational age (LGA. The Infant Feeding Practices Study II, a prospective cohort study, surveyed pregnant women during their 3rd trimester, of which a subgroup (n=893 completed a food frequency questionnaire. Maternal dietary patterns were evaluated by diet scores (Alternative Healthy Eating Index for Pregnancy and alternate Mediterranean diet and by carbohydrate quality (glycemic index and glycemic load. Poisson regression with robust standard errors was used to examine the relative risk of SGA and separately LGA, with dietary patterns and other lifestyle factors. Linear regression was used to determine the association of birthweight and early infant growth with better dietary patterns. Relative risk of SGA and LGA was not associated with dietary patterns. Birthweight and infant growth were not associated with maternal diet. Smoking, however, increased the risk of delivering an SGA infant (RR = 2.92, 95% CI: 1.58–5.39, while higher prepregnancy BMI increased the risk of delivering an LGA infant (RR = 1.06, 95% CI: 1.03–1.09. Future studies are needed to evaluate whether deficiencies in more specific maternal dietary nutrients play a role in fetal growth.
Directory of Open Access Journals (Sweden)
Arheden Hakan
2009-10-01
Full Text Available Abstract Background This study aims to present a novel method for using cardiovascular magnetic resonance (CMR to non-invasively quantify the variation in pulmonary blood volume throughout the cardiac cycle in humans. Methods 10 healthy volunteers (7 males, 3 female, age range 21-32 years were studied. The blood flow in the pulmonary artery and all pulmonary veins was quantified during free breathing using phase contrast velocity encoded CMR. The difference in flow between the pulmonary artery and the pulmonary veins was integrated to calculate the change in pulmonary blood volume throughout the cardiac cycle. Results The stroke volumes in the pulmonary artery and the sum of the pulmonary veins were (mean ± SEM 103 ± 6 ml and 95 ± 6 ml, respectively. The pulmonary blood volume variation (PBVV was 48 ± 5 ml, and the PBVV expressed as percent of the pulmonary artery stroke volume was 46 ± 3%. The maximum increase in pulmonary blood volume occurred 310 ± 12 ms after the R-wave from the ECG (32 ± 2% of the cardiac cycle. PBVV did not correlate to change in cross-sectional area in the pulmonary artery (R2 = 0.03, p = 0.66. Conclusion It is feasible to non-invasively quantify the change in pulmonary blood volume during the cardiac cycle in humans using CMR. The average pulmonary blood volume variation in healthy volunteers was approximately 50 ml and this was approximately 50% of the stroke volume. Further studies are needed to assess the utility of the pulmonary blood volume variation as a measure for identifying cardiac and pulmonary vascular disease.
Energy Technology Data Exchange (ETDEWEB)
Marder, P.; Schmidtke, J.R.
1983-08-01
The inhibition of concanavalin A-induced human peripheral blood lymphocyte blastogenesis by methylprednisolone (MP) was studied by using flow cytometry and tritiated thymidine (/sup 3/H-TdR) incorporation. Flow cytometric determinations of volume, low angle forward light scatter, and nucleic acid showed MP to be a potent inhibitor of blastogenesis. The effects were concentration-dependent and correlated with /sup 3/H-TdR uptake. By using the single cell analytic capability of flow cytometry, the target stages of the cell cycle where MP affects lymphocyte activation were determined. Evidence is presented that steroids can block both early and late phases of this process.
Deen, Niels G.; Sint Annaland, van Martin; Kuipers, J.A.M.
2007-01-01
In this paper a hybrid model is presented for the numerical simulation of gas-liquid-solid flows using a combined Volume Of Fluid (VOF) and Discrete Particle (DP) approach applied for respectively dispersed gas bubbles and solid particles present in the continuous liquid phase. The hard sphere DP mo
Deen, Niels G.; Sint Annaland, van Martin; Kuipers, J.A.M.
2006-01-01
In this paper a hybrid model is presented for the numerical simulation of gas-liquid-solid flows using a combined Volume Of Fluid (VOF) and Discrete Particle (DP) approach applied for respectively dispersed gas bubbles and solid particles present in the continuous liquid phase. The hard sphere DP mo
Institute of Scientific and Technical Information of China (English)
Xing-Chan Li; Cui-Xia Liang; Jing Li; Pei-Feng Li; Yu Zhao
2016-01-01
Objective:To study the effect of hysteroscopic adhesiolysis combined with growth hormone on endometrial blood flow and volume as well as Smad2/3 expression.Methods: A total of 64 patients with moderate or severe intrauterine adhesions who received hysteroscopic adhesiolysis in our hospital from May 2013 to October 2015 were selected as the research subjects and randomly divided into two groups who received different postoperative drug treatment, observation group received postoperative manual cycle intervention combined with growth hormone treatment and control group only received manual cycle intervention. Transvaginal ultrasonography was conducted after treatment to assess endometrial thickness, volume and blood flow, and endometrium was collected to determine Smad2, Smad3 and TGF-β1 levels.Results:After treatment, endometrial blood flow signal of observation group was more abundant than that of control group, ultrasound parameters RI and PI were significantly lower than those of control group, and VI, FI and VFI as well as endometrial thickness and endometrial cavity volume were significantly higher than those of control group; Smad2, Smad3 and TGF-β1 levels in endometrial tissue of observation group after treatment were significantly lower than those of control group.Conclusions:Hysteroscopic adhesiolysis combined with growth hormone therapy can promote endometrial repair and growth, increase endometrial blood flow and volume and also suppress the expression of Smad2/3 and TGF-β1 in patients with intrauterine adhesions.
LENUS (Irish Health Repository)
Khashan, A S
2012-01-31
BACKGROUND: Adverse pregnancy outcomes have been associated with maternal celiac disease (CD). In this study, we investigate the effect of treated and untreated maternal CD on infant birthweight and preterm birth. METHODS: A population-based cohort study consisted of all singleton live births in Denmark between 1 January 1979 and 31 December 2004 was used. A total of 1,504,342 babies were born to 836,241 mothers during the study period. Of those, 1105 babies were born to women with diagnosed CD and 346 were born to women with undiagnosed CD. Women with diagnosed CD were considered as treated with a gluten free diet while women with undiagnosed CD were considered as untreated. The outcome measures were: birthweight, small for gestational age (SGA: birthweight <10th centile), very small for gestational age (VSGA: birthweight <5th centile) and preterm birth. We compared these measures in treated and untreated women with those of a reference group (no history of CD). RESULTS: Women with untreated CD delivered smaller babies [difference = -98 g (95% CI: -130, -67)], with a higher risk of SGA infants [OR = 1.31 (95% CI: 1.06, 1.63)], VSGA infants [OR = 1.54 (95% CI: 1.17, 2.03)] and preterm birth [OR = 1.33 (95% CI: 1.02, 1.72)] compared with women without CD. Women with treated CD had no increased risk of reduced mean birthweight, risk of delivering SGA and VSGA infants or preterm birth compared with women without CD. CONCLUSION: Untreated maternal CD increases the risk of reduced birthweight, the risk of delivering SGA and VSGA infants and preterm birth. Diagnosis and presumed treatment of maternal CD with a gluten-free diet appeared to result in a birthweight and preterm birth rate similar to those in women without CD.
Danileviciute, Asta; Grazuleviciene, Regina; Paulauskas, Algimantas; Nadisauskiene, Ruta; Nieuwenhuijsen, Mark J
2012-12-26
Genetic susceptibility to tobacco smoke might modify the effect of smoking on pregnancy outcomes. We conducted a case-control study of 543 women who delivered singleton live births in Kaunas (Lithuania), examining the association between low-level tobacco smoke exposure (mean: 4.8 cigarettes/day) during pregnancy, GSTT1 and GSTM1 polymorphisms and birthweight of the infant. Multiple linear-regression analysis was performed adjusting for gestational age, maternal education, family status, body mass index, blood pressure, and parity. Subsequently, we tested for the interaction effect of maternal smoking, GSTT1 and GSTM1 genes polymorphisms with birthweight by adding all the product terms in the regression models. The findings suggested a birthweight reduction among light-smoking with the GSTT1-null genotype (-162.9 g, P = 0.041) and those with the GSTM1-null genotype (-118.7 g, P = 0.069). When a combination of these genotypes was considered, birthweight was significantly lower for infants of smoking women the carriers of the double-null genotypes (-311.2 g, P = 0.008). The interaction effect of maternal smoking, GSTM1 and GSTT1 genotypes was marginally significant on birthweight (-234.5 g, P = 0.078). Among non-smokers, genotype did not independently confer an adverse effect on infant birthweight. The study shows the GSTT1-null genotype, either presents only one or both with GSTM1-null genotype in a single subject, have a modifying effect on birthweight among smoking women even though their smoking is low level. Our data also indicate that identification of the group of susceptible subjects should be based on both environmental exposure and gene polymorphism. Findings of this study add additional evidence on the interplay among two key GST genes and maternal smoking on birth weight of newborns.
Directory of Open Access Journals (Sweden)
Yun Seok Choi
2014-01-01
Full Text Available This work develops a grid based rainfall-runoff model (GRM, which is a physically based and spatially distributed model. Surface flow was analyzed using a kinematic wave model with the governing equations discretized using the finite volume method (FVM. This paper suggests a grid network flow analysis technique using variable rainfall intensity according to the flow directions to analyze one-dimensional flows between the grids. The model was evaluated by applying it to the Wuicheon watershed, a tributary of the Nakdonggang (Riv., in Korea. The results showed that the grid-based, one-dimensional kinematic wave model adopted the FVM and the grid network flow analysis technique well. The simulation results showed good agreement with the observed hydrographs and the initial soil saturation ratio was most sensitive to the modeling results.
Directory of Open Access Journals (Sweden)
Ehmer Ulrike
2005-10-01
Full Text Available Abstract Background Well-designed clinical studies on the palatal development in preterm and low birthweight infants are desirable because the literature is characterized by contradictory results. It could be shown that knowledge about 'normal' palatal development is still weak as well (Part 1. The objective of this review is therefore to contribute a fundamental analysis of methodologies, confounding factors, and outcomes of studies on palatal development in preterm and low birthweight infants. Methods An electronic literature search as well as hand searches were performed based on Cochrane search strategies including sources of more than a century in English, German, and French. Original data were recalculated from studies which primarily dealt with both preterm and term infants. The extracted data, especially those from non-English paper sources, were provided unfiltered for comparison. Results Seventy-eight out of 155 included articles were analyzed for palatal morphology of preterm infants. Intubation, feeding tubes, feeding mode, tube characteristics, restriction of oral functions, kind of diet, cranial form and birthweight were seen as causes contributing to altered palatal morphology. Changes associated with intubation concern length, depth, width, asymmetry, crossbite, and contour of the palate. The phenomenon 'grooving' has also been described as a complication associated with oral intubation. However, this phenomenon suffers from lack of a clear-cut definition. Head flattening, pressure from the oral tube, pathologic or impaired tongue function, and broadening of the alveolar ridges adjacent to the tube have been raised as causes of 'grooving'. Metrically, the palates of intubated preterm infants remain narrower, which has been examined up to the age of the late mixed dentition. Conclusion There is no evidence that would justify the exclusion of any of the raised causes contributing to palatal alteration. Thus, early orthodontic and
Institute of Scientific and Technical Information of China (English)
LI Hua; WANG Mi; WU Ying-xiang; MA Yi-xin; WILLIAMS Richard
2005-01-01
This paper presents the use of a high performance dual-plane electrical resistance tomography (ERT) system and a local dual-sensor conductance probe to measure the vertical upward oil-in-water pipe flows in which the mean oil volume fraction is up to 23.1%.A sensitivity coefficient back-projection (SBP) algorithm was adopted to reconstruct the flow distributions and a cross correlation method was applied to obtain the oil velocity distributions. The oil volume fraction and velocity distributions obtained from both measurement techniques were compared and good agreement was found, which indicates that the ERT technique can be used to measure the low fraction oil-water flows. Finally, the factors affecting measurement precision were discussed.
Sojkova, Jitka; Goh, Joshua; Bilgel, Murat; Landman, Bennett; Yang, Xue; Zhou, Yun; An, Yang; Beason-Held, Lori L.; Kraut, Michael A.; Wong, Dean F.; Resnick, Susan M.
2017-01-01
Quantification of β-amyloid (Aβ) in vivo is often accomplished using the distribution volume ratio (DVR), based on a simplified reference tissue model. We investigated the local relationships between DVR and cerebral blood flow (CBF), as well as relative blood flow (R1), in nondemented older adults. Methods Fifty-five nondemented participants (mean age 78.5 years) in the Baltimore Longitudinal Study of Aging underwent 15O-H2O PET CBF and dynamic 11C-PiB-PET. 15O-H2O PET images were normalized and smoothed using SPM. A simplified reference tissue model with linear regression and spatial constraints was used to generate parametric DVR images. The DVR images were regressed on CBF images on a voxel-by-voxel basis using robust Biological Parametric Mapping, adjusting for age and sex (FDR p=0.05, k=50). DVR images were also regressed on R1 images, a measure of the transport rate constant from vascular space to tissue. All analyses were performed in the entire sample, and in high and low tertiles of mean cortical DVR. Results Voxel-based analyses showed that increased DVR is associated with increased CBF in frontal, parietal, temporal, and occipital cortices. However, this association appears to spare regions that typically show early β-amyloid (Aβ) deposition. A more robust relationship between DVR and CBF was observed in the lowest tertile of DVR, i.e., negligible cortical Aβ load, compared to the highest tertile of cortical DVR and Aβ load. Spatial distributions of the DVR-CBF and DVR-R1 correlations showed similar patterns. No reliable negative voxel-wise relationships between DVR and CBF or R1 were observed. Conclusion Robust associations between DVR and CBF at negligible Aβ levels, together with similar spatial distributions of DVR-CBF and DVR-R1 correlations, suggest that regional distribution of DVR reflects blood flow and tracer influx rather than pattern of Aβ deposition in those with minimal Aβ load. DVR-CBF associations in individuals with higher DVR
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McCommis, Kyle S.; Goldstein, Thomas A.; Pilgram, Thomas [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Abendschein, Dana R. [Washington University School of Medicine, Center for Cardiovascular Research, St. Louis, MO (United States); Misselwitz, Bernd [Bayer Schering Pharma AG, Berlin (Germany); Gropler, Robert J. [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Washington University School of Medicine, Center for Cardiovascular Research, St. Louis, MO (United States); Zheng, Jie [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Cardiovascular Imaging Lab, St. Louis, MO (United States)
2010-08-15
To validate fast perfusion mapping techniques in a setting of coronary artery stenosis, and to further assess the relationship of absolute myocardial blood volume (MBV) and blood flow (MBF) to global myocardial oxygen demand. A group of 27 mongrel dogs were divided into 10 controls and 17 with acute coronary stenosis. On 1.5-T MRI, first-pass perfusion imaging with a bolus injection of a blood-pool contrast agent was performed to determine myocardial perfusion both at rest and during either dipyridamole-induced vasodilation or dobutamine-induced stress. Regional values of MBF and MBV were quantified by using a fast mapping technique. Color microspheres and {sup 99m}Tc-labeled red blood cells were injected to obtain respective gold standards. Microsphere-measured MBF and {sup 99m}Tc-measured MBV reference values correlated well with the MR results. Given the same changes in MBF, changes in MBV are twofold greater with dobutamine than with dipyridamole. Under dobutamine stress, MBV shows better association with total myocardial oxygen demand than MBF. Coronary stenosis progressively reduced this association in the presence of increased stenosis severity. MR first-pass perfusion can rapidly estimate regional MBF and MBV. Absolute quantification of MBV may add additional information on stenosis severity and myocardial viability compared with standard qualitative clinical evaluations of myocardial perfusion. (orig.)
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Meguro,Tadamichi
1991-02-01
Full Text Available Pulmonary function tests were performed on 252 healthy young subjects free from respiratory and allergic symptoms, and 80 young subjects with past history of nasal allergy (PNA and 10 subjects with past history of bronchial asthma (PBA. All the subjects were non-smokers. Maximal expiratory flow-volume (MEFV curves were visually classified into five types (A-E. The percent distribution of type A in healthy subjects was significantly higher than in the PNA group, while the total sum of percentage of types B, C, and D in the PNA group was significantly higher than in the healthy subjects. The percent distribution of type E in the PNA group was similar to that in the healthy subjects. The percent distribution of MEFV types were significantly different between healthy males and healthy females. The percent distribution of types A, B and E were the highest in healthy subjects, PNA and PBA groups, respectively. Conclusively, the difference in the percent distributions of MEFV types was recognized among healthy subjects, PNA and PBA groups.
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Kawamoto, Hitoshi; Kambe, Masayuki; Yamagata, Mitsunori; Nakajima, Hidekatsu [Hiroshima Univ. (Japan). School of Medicine; Yamane, Kousuke; Kuraoka, Toshihiko; Miyamura, Isao
2001-08-01
This study was conducted to verify whether bronchial asthma (BA) alone causes pulmonary emphysema (PE), and to examine the computed tomography (CT) findings in non-smokers with BA demonstrating the flow volume curve (FV curve) characteristic of PE. Non-smoking patients with a history of BA for more than 20 years were divided into 2 groups: the dogleg pattern group (n=5), with an FV curve characteristic of PE, and the concave pattern group (n=16) with an FV curve characteristic of BA. CT scans was performed using CT values (level, 900 H.U.; width, 400 H.U.) that facilitate detection of a low attenuation area (LAA), and using conventional CT values (level, 700 H.U.; width, 1,300 H.U.). LAA (including air trapping), thickness of the bronchial wall, and partial atelectasis were compared between the 2 groups. PE was not detected, although air trapping was found in all subjects. The thickness of the airway was greater in the dogleg pattern than in the concave pattern. The incidences of air trapping and partial atelectasis were higher in the former than in the latter. BA alone may not cause PE. Some BA patients without PE show the FV curve characteristic of PE, reflecting an increase in the thickness of the airway wall and a decrease in the pulmonary ventilation probably due to the air trapping and the partial atelectasis. (author)
DNS of horizontal open channel flow with finite-size, heavy particles at low solid volume fraction
Kidanemariam, Aman G; Doychev, Todor; Uhlmann, Markus
2013-01-01
We have performed direct numerical simulation of turbulent open channel flow over a smooth horizontal wall in the presence of finite-size, heavy particles. The spherical particles have a diameter of approximately 7 wall units, a density of 1.7 times the fluid density and a solid volume fraction of 0.0005. The value of the Galileo number is set to 16.5, while the Shields parameter measures approximately 0.2. Under these conditions, the particles are predominantly located in the vicinity of the bottom wall, where they exhibit strong preferential concentration which we quantify by means of Voronoi analysis and by computing the particle-conditioned concentration field. As observed in previous studies with similar parameter values, the mean streamwise particle velocity is smaller than that of the fluid. We propose a new definition of the fluid velocity "seen" by finite-size particles based on an average over a spherical surface segment, from which we deduce in the present case that the particles are instantaneousl...
Wei, Hua-Liang; Zheng, Ying; Pan, Yi; Coca, Daniel; Li, Liang-Min; Mayhew, J E W; Billings, Stephen A
2009-06-01
It is well known that there is a dynamic relationship between cerebral blood flow (CBF) and cerebral blood volume (CBV). With increasing applications of functional MRI, where the blood oxygen-level-dependent signals are recorded, the understanding and accurate modeling of the hemodynamic relationship between CBF and CBV becomes increasingly important. This study presents an empirical and data-based modeling framework for model identification from CBF and CBV experimental data. It is shown that the relationship between the changes in CBF and CBV can be described using a parsimonious autoregressive with exogenous input model structure. It is observed that neither the ordinary least-squares (LS) method nor the classical total least-squares (TLS) method can produce accurate estimates from the original noisy CBF and CBV data. A regularized total least-squares (RTLS) method is thus introduced and extended to solve such an error-in-the-variables problem. Quantitative results show that the RTLS method works very well on the noisy CBF and CBV data. Finally, a combination of RTLS with a filtering method can lead to a parsimonious but very effective model that can characterize the relationship between the changes in CBF and CBV.
Loubère, Raphaël; Ghidaglia, Jean-Michel
2010-01-01
This work concerns the simulation of compressible multi-material fluid flows and follows the method FVCF-NIP described in the former paper Braeunig et al (Eur. J. Mech. B/Fluids, 2009). This Cell-centered Finite Volume method is totally Eulerian since the mesh is not moving and a sharp interface, separating two materials, evolves through the grid. A sliding boundary condition is enforced at the interface and mass, momentum and total energy are conserved. Although this former method performs well on 1D test cases, the interface reconstruction suffers of poor accuracy in conserving shapes for instance in linear advection. This situation leads to spurious instabilities of the interface. The method Enhanced-NIP presented in the present paper cures an inconsistency in the former NIP method that improves strikingly the results. It takes advantage of a more consistent description of the interface in the numerical scheme. Results for linear advection and compressible Euler equations for inviscid fluids are presented ...
Kirkil, Gokhan
2016-11-01
The effect of the Solid Volume Fraction (SVF) on the flow structure within and past a circular array of surface-mounted cylinders that extends over 75% of the water depth, h is investigated using Detached Eddy Simulation (DES). This set up mimics the case of a submerged patch of rigid vegetation in a channel. The diameter of the cylinders in the array is d = 0.02D, where D is the diameter of the circular array. The channel Reynolds number is close to 20,000 and the Reynolds number defined with D is around 24,000. DES is conducted for SVF = 10% and 25%. It is found that as the SVF increases, fairly strong horseshoe vortex system forms around the upstream face of the vegetation patch, the strength of the separated shear layers on the sides of the vegetation patch increases and the length of the recirculation region behind the patch decreases. While an increase of the SVF results in a large increase of the turbulent kinetic energy in the wake, the opposite is observed within the porous vegetation patch.
Qin, J. J.; Jones, M.; Shiota, T.; Greenberg, N. L.; Firstenberg, M. S.; Tsujino, H.; Zetts, A. D.; Sun, J. P.; Cardon, L. A.; Odabashian, J. A.; Flamm, S. D.; White, R. D.; Panza, J. A.; Thomas, J. D.
2000-01-01
AIM: The aim of this study was to investigate the feasibility and accuracy of using symmetrically rotated apical long axis planes for the determination of left ventricular (LV) volumes with real-time three-dimensional echocardiography (3DE). METHODS AND RESULTS: Real-time 3DE was performed in six sheep during 24 haemodynamic conditions with electromagnetic flow measurements (EM), and in 29 patients with magnetic resonance imaging measurements (MRI). LV volumes were calculated by Simpson's rule with five 3DE methods (i.e. apical biplane, four-plane, six-plane, nine-plane (in which the angle between each long axis plane was 90 degrees, 45 degrees, 30 degrees or 20 degrees, respectively) and standard short axis views (SAX)). Real-time 3DE correlated well with EM for LV stroke volumes in animals (r=0.68-0.95) and with MRI for absolute volumes in patients (r-values=0.93-0.98). However, agreement between MRI and apical nine-plane, six-plane, and SAX methods in patients was better than those with apical four-plane and bi-plane methods (mean difference = -15, -18, -13, vs. -31 and -48 ml for end-diastolic volume, respectively, Pmeasurement methods of real-time 3DE correlated well with reference standards for calculating LV volumes. Balancing accuracy and required time for these LV volume measurements, the apical six-plane method is recommended for clinical use.
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Meguro,Tadamichi
1978-10-01
Full Text Available With the parameters of a flow-volume and a volume-time curve, the discriminant analysis of bronchial asthma is described. The subjects were classified into three groups (healthy adults, mild asthmatic patients and moderates ones. The difference of the mean vectors of the parameters of the three groups was made clear by the selection methods of the discriminant analysis between any two of the groups both with 6 parameters (%FVC, FEV1.0%, peak flow rate (PF, flow rate at 50% of FVC (V50, flow rate at 25% of FVC (V25, and V50/V25 and with 8 (6 parameters mentioned above and V75, V10. Forced expiratory volume in 1 second percent (FEV1.0% or V50 was selected at the first step with 6 parameters, and V75 was selected at the first step with 8 parameters. Probabilities of misclassification with 8 parameters were lower than those with 6 ones and the probability of misclassification at the discriminant analysis between healthy adults and mild asthmatic patients with 8 parameters was 15.75% at the final step.
DEFF Research Database (Denmark)
Jung, Mette H; Hassager, Christian; Balling, Louise;
2015-01-01
Pulmonary capillary wedge pressure (PCWP) is the key to describing left ventricular (LV) unloading, however, the relation between pressure and the echocardiography-derived surrogate of LV volume (left ventricular end-diastolic diameter (LVEDD)) as a function of pump speed (RPM) in continuous......-flow left ventricular assist device (CF-LVAD) patients is unknown. In this study the pressure-volume relationship as a function of RPM during ramp testing was investigated by simultaneously measuring PCWP by Swan-Ganz catheter and LVEDD by echocardiography. The ramp protocol started at usual pump setting...
Accuracy and correlates of maternal recall of birthweight and gestational age
DEFF Research Database (Denmark)
Adegboye, Amanda Rodrigues Amorim; Heitmann, B.
2008-01-01
the two sources was evaluated by mean differences (MD), intraclass correlation coefficient (ICC) and Bland-Altman's plots. The misclassification of the various BW and GA categories were also estimated. MAIN OUTCOME MEASURES: Differences between recalled and registered BW and GA. RESULTS: There was high......OBJECTIVE: To determine the accuracy of maternal recall of children birthweight (BW) and gestational age (GA), using the Danish Medical Birth Register (DBR) as reference and to examine the reliability of recalled BW and its potential correlates. DESIGN: Comparison of data from the DBR...
Rosenbaum, P; Saigal, S; Szatmari, P; Hoult, L
1995-07-01
This study reports moderate to high Pearson correlations between Vineland Adaptive Behavior Scale (VABS) subscale and total scores and a variety of cognitive, academic and motor performance tests on a population of extremely low-birthweight infants assessed at eight years of age. The subscales describe adaptive behaviour in daily living, communication, motor function and socialization, as well as an adaptive behaviour composite score. Because it can provide a norm-referenced description of functional outcomes and can be used to assess all children regardless of disability, the authors believe that the VABS should be applied uniformly by all groups reporting school-age outcome of neonatal intensive-care populations.
DEFF Research Database (Denmark)
Minja, Daniel T R; Schmiegelow, Christentze; Mmbando, Bruno;
2013-01-01
Intermittent preventive treatment during pregnancy with sulfadoxine-pyrimethamine (IPTp-SP) is a key strategy in the control of pregnancy-associated malaria. However, this strategy is compromised by widespread drug resistance from single-nucleotide polymorphisms in the Plasmodium falciparum...... dihydrofolate reductase and dihydropteroate synthetase genes. During September 2008-October 2010, we monitored a cohort of 924 pregnant women in an area of Tanzania with declining malaria transmission. P. falciparum parasites were genotyped, and the effect of infecting haplotypes on birthweight was assessed...
Directory of Open Access Journals (Sweden)
D. C. Kilpatrick
1993-01-01
Full Text Available The mean birthweight of babies eventually born to couples with a history of recurrent spontaneous abortion (RSA is allegedly lower if the parents have a high degree of HLA antigen sharing (Reznikoff-Etievant et al., 1991, but this relationship has not been independently confirmed. We have re-investigated this question by analysing data from 36 families. In 22 instances, we were able to relate birthweight directly to feto-maternal HLA compatibility for the first time in such families. We were unable to confirm any appreciable influence of paternal or feto-maternal HLA sharing on birthweight or placental weight and conclude that RSA families do not differ markedly from normal families in this respect.
IJzerman, R.G.; Boomsma, D.I.; Stehouwer, C.D.A.
2005-01-01
Evidence has accumulated that low birthweight is associated with several risk factors for cardiovascular disease. However, it is not known whether or not these associations are due to a programmed response to intrauterine malnutrition or genetic factors influencing both birthweight and
Directory of Open Access Journals (Sweden)
Shai Mulinari
Full Text Available Many public health and epidemiological studies have found differences between populations (e.g. maternal countries of birth in average values of a health indicator (e.g. mean offspring birthweight. However, the approach based solely on population-level averages compromises our understanding of variability in individuals' health around the averages. If this variability is high, the exclusive study of averages may give misleading information. This idea is relevant when investigating country of birth differences in health.To exemplify this concept, we use information from the Swedish Medical Birth Register (2002-2010 and apply multilevel regression analysis of birthweight, with babies (n = 811,329 at the first, mothers (n = 571,876 at the second, and maternal countries of birth (n = 109 at the third level. We disentangle offspring, maternal and maternal country of birth components of the total offspring heterogeneity in birthweight for babies born within the normal timespan (37-42 weeks. We found that of such birthweight variation about 50% was at the baby level, 47% at the maternal level and only 3% at the maternal countries of birth level.In spite of seemingly large differences in average birthweight among maternal countries of birth (range 3290-3677 g, knowledge of the maternal country of birth does not provide accurate information for ascertaining individual offspring birthweight because of the high inter-offspring heterogeneity around country averages. Our study exemplifies the need for a better understanding of individual health diversity for which group averages may provide insufficient and even misleading information. The analytical approach we outline is therefore relevant to investigations of country of birth (and ethnic differences in health in general.
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
New form of the constitutive equations for the Oldroyd-B model, which have physical meaning, is developed to facilitate theoretical analysis. The new equations are used to simulate planar 4∶1 contraction flow of a Maxwell fluid using a third-order upwind finite volume method. The numerical results compare well with the theoretical solutions and the results of other references to show the effectiveness of the numerical method. Numerical experiments suggest that the present method not only converges fairly rapidly, but can also generate a highly resolved approximation to an Oldroyd-B fluid flow at a high Weissenberg number.
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Karen L Heathcote
2011-01-01
Full Text Available Pulmonary function tests in patients with idiopathic pulmonary fibrosis characteristically show a restrictive pattern including small lung volumes and increased expiratory flow rates resulting from a reduction in pulmonary compliance due to diffuse fibrosis. Conversely, an obstructive pattern with hyperinflation results in emphysema by loss of elastic recoil, expiratory collapse of the peripheral airways and air trapping. When the diseases coexist, pulmonary volumes are compensated, and a smaller than expected reduction or even normal lung volumes can be found. The present report describes 10 patients with progressive breathlessness, three of whom experienced severe limitation in their quality of life. All patients showed lung interstitial involvement and emphysema on computed tomography scan of the chest. The 10 patients showed normal spirometry and lung volumes with severe compromise of gas exchange. Normal lung volumes do not exclude diagnosis of idiopathic pulmonary fibrosis in patients with concomitant emphysema. The relatively preserved lung volumes may underestimate the severity of idiopathic pulmonary fibrosis and attenuate its effects on lung function parameters.
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Sosniak, W.A.; Kaye, W.E. (Agency for Toxic Substances and Disease Registry, Atlanta, GA (United States)); Gomez, T.M. (Centers for Disease Control and Prevention, Atlanta, GA (United States))
Data from the 1988 National Maternal and Infant Health Survey files were linked with data from the 1990 Environmental Protection Agency National Priorities List of hazardous waste sites to determine whether any relationship existed between living in proximity to hazardous waste sites and low birthweight. The odds ratio for low birthweight versus normal birthweight was 1.03 (95% confidence internal [95% Cl] = 0.98-1.16), and remained at 0.99 (95% Cl = 0.86-1.16) when adjusted for maternal age, parity, infant sex, prenatal care, and behavioral and socioeconomic factors. Very low birthweight, infant and fetal death, prematurity, and congenital malformation were not found to be associated with living in the vicinity of a hazardous waste site during pregnancy. Merging a large population database with environmental data proved to be an innovative but not very efficient method of assessing the risks of low birthweight related to the environment. 20 refs., 4 tabs.
Directory of Open Access Journals (Sweden)
Owens David GC
2008-01-01
Full Text Available Abstract Background Although neuroanatomical and cognitive sequelae of low birthweight and preterm birth have been investigated, little is understood as to the likely prevalence of a history of low birthweight or preterm birth, or neuroanatomical correlates of such a history, within the special educational needs population. Our aim was to address these issues in a sample of young people receiving additional learning support. Methods One hundred and thirty-seven participants aged 13–22 years, receiving additional learning support, were recruited via their schools or colleges and underwent structural magnetic resonance imaging (MRI. Obstetric records, available in 98 cases, included birthweight and gestational data in 90 and 95 cases, respectively. Both qualitative and quantitative voxel-based analyses of MRI data were conducted. Results A history of low birthweight and preterm birth was present in 13.3% and 13.7% of cases, respectively. Low birthweight and preterm birth were associated with specific qualitative anomalies, including enlargement of subarachnoid cisterns and thinning of the corpus callosum. Low birthweight was associated with reduced grey matter density (GMD in the superior temporal gyrus (STG bilaterally, left inferior temporal gyrus and left insula. Prematurity of birth was associated with reduced GMD in the STG bilaterally, right inferior frontal gyrus and left cerebellar hemisphere. Comparison of subjects with no history of low birthweight or preterm birth with a previously defined control sample of cognitively unimpaired adolescents (n = 72 demonstrated significantly greater scores for several anomalies, including thinning of the corpus callosum, loss of white matter and abnormalities of shape of the lateral ventricles. Conclusion Although a two-fold increased prevalence of a history of low birthweight and preterm birth exists within the special educational needs population, other aetiological factors must be considered for
Friedlander, Yechiel; Manor, Orly; Paltiel, Ora; Meiner, Vardiella; Sharon, Nir; Calderon, Ronit; Hochner, Hagit; Sagy, Yael; Avgil, Meytal; Harlap, Susan; Siscovick, David S.
2009-01-01
Purpose To explore the association between birthweight in offspring, a marker of the intrauterine environment, and mortality in their mothers taking into account maternal pre-pregnancy characteristics, including maternal BMI, smoking, and socioeconomic status. Distinguishing the effects of offspring’s birthweight and pre-pregnancy characteristics on maternal outcome may provide clues regarding mechanisms underlying the association between birth weight and maternal mortality. Methods We studied long-term total mortality (average follow-up period 29.1 years) in a population-based cohort of 13,185 mothers, aged 15 to 48 years at their offspring’s birth, who delivered in West Jerusalem during 1974–76 Results Univariate and multivariate Cox-proportional hazard models used to estimate the hazard of overall mortality among mothers indicated a non-linear relationship with birthweight of offspring when introduced into the models as a continuous variable, and a linear positive association with maternal pre-pregnancy BMI. Inclusion of maternal BMI and other pre-pregnancy characteristics in the model did not alter the association between offspring’s birthweight and mothers’ all-cause mortality. When birthweight was introduced as a categorical variable, higher mortality was observed among mothers who gave birth to babies with birthweight < 2500 gr (HR=1.90; 95%CI 1.23–2.94) as compared to mothers whose offspring had birthweight between 3000 and 3499 gr. The hazard ratio for mothers who gave birth to babies with birth weight ≥ 4000 gr was 1.30 (95%CI 0.88–1.91). Conclusions Independent of pre-pregnancy maternal BMI and other characteristics, birthweight of offspring was associated with mortality in their mothers, suggesting that intra-uterine metabolic events reflected by birth weight and not explained by maternal obesity, smoking, and SES have remote consequences for maternal health. These findings underline the need to explore specific genetic and
DEFF Research Database (Denmark)
Jacobsen, Stine C; Gillberg, Linn; Bork-Jensen, Jette
2014-01-01
individuals, and we recently showed multiple DNA methylation changes during short-term high-fat overfeeding in muscle of healthy people. In a randomised crossover study, we analysed genome-wide DNA promoter methylation in skeletal muscle of 17 young LBW men and 23 matched normal birthweight (NBW) men after......The association between low birthweight (LBW) and risk of developing type 2 diabetes may involve epigenetic mechanisms, with skeletal muscle being a prime target tissue. Differential DNA methylation patterns have been observed in single genes in muscle tissue from type 2 diabetic and LBW...
A volume-of-fluid formulation for the study of co-flowing fluids governed by the Hele-Shaw equations
Afkhami, Shahriar
2013-01-01
We present a computational framework to address the flow of two immiscible viscous liquids which co-flow into a shallow rectangular container at one side, and flow out into a holding container at the opposite side. Assumptions based on the shallow depth of the domain are used to reduce the governing equations to one of Hele-Shaw type. The distinctive feature of the numerical method is the accurate modeling of the capillary effects. A continuum approach coupled with a volume-of-fluid formulation for computing the interface motion and for modeling the interfacial tension in Hele-Shaw flows is formulated and implemented. The interface is reconstructed with a height-function algorithm. The combination of these algorithms is a novel development for the investigation of Hele-Shaw flows. The order of accuracy and convergence properties of the method are discussed with benchmark simulations. A microfluidic flow of a ribbon of fluid which co-flows with a second liquid is simulated. We show that for small capillary num...
Adam, A.; Pavlidis, D.; Percival, J. R.; Salinas, P.; Xie, Z.; Fang, F.; Pain, C. C.; Muggeridge, A. H.; Jackson, M. D.
2016-09-01
A general, higher-order, conservative and bounded interpolation for the dynamic and adaptive meshing of control-volume fields dual to continuous and discontinuous finite element representations is presented. Existing techniques such as node-wise interpolation are not conservative and do not readily generalise to discontinuous fields, whilst conservative methods such as Grandy interpolation are often too diffusive. The new method uses control-volume Galerkin projection to interpolate between control-volume fields. Bounded solutions are ensured by using a post-interpolation diffusive correction. Example applications of the method to interface capturing during advection and also to the modelling of multiphase porous media flow are presented to demonstrate the generality and robustness of the approach.
Very-low-birthweight neonates: do outcomes differ in multiple compared with singleton gestations?
Hayes, Edward J; Paul, David; Ness, Amen; Mackley, Amy; Berghella, Vincenzo
2007-06-01
The purpose of this study is to determine if outcomes for very-low-birthweight (VLBW) neonates differ in multiple versus singleton gestations. This is a retrospective cohort study of neonates weighing less than 1500 g admitted to a neonatal intensive care unit from 1993 to 2004. Outcome variables were necrotizing enterocolitis, death, and/or severe intraventricular hemorrhage (IVH). Statistical analysis included univariate and multivariate analysis. During the study period, 1769 VLBW infants including 465 multiples and 1304 singletons were identified. Gestational age and birthweight were similar; conversely white race (68% multiples versus 43% singletons), maternal age (28.7 +/- 5.7 versus 26.1 +/- 6.5 years), born at facility (95% versus 86%), antenatal steroids (74% versus 58%), preeclampsia (14% versus 24%), and preterm labor (74% versus 62%) were significantly different. Correcting for these, VLBW multiples had a higher odds ratio (OR) of death and/or severe IVH, OR 1.4 (1.03-1.95). In our population, VLBW multiple gestations were at elevated odds for death and/or severe IVH compared with VLBW singletons.
Mohamed, Abdelrahim Awadelkarim Abdelrahman; Almalaq, Abdulrahman Ahmed Abdullah; Almansour, Raed Dawood Mohammed; Alanazi, Haitham Samer Abdulaziz; Al-Khamali, Mohammad Mosa; Shommo, Sohair Ali Mohammed
2015-11-01
The aim of this study was to determine the mode of delivery and birthweight among teenagers in comparison to adult pregnant Saudi women. This was a retrospective comparative study. We included all primigravid teenage girls aged 19 years or younger and adult women aged 20-29 years with singleton term normal pregnancies who delivered at Hail Maternity Hospital during 1 January-31 December 2013. Incidence of vaginal delivery among teenagers was higher than that in adults, at 105 (80.2%) and 588 (70.5%), respectively. There was a lower incidence of vacuum extraction and cesarean section among the teenage group compared to the adult group (1 [0.8%] vs 25 [3.0%], and 25 [19.1%] vs 221 [26.5%], respectively [P > 0.05]). Incidence of low birthweight among the teenage group was higher than that in adults (28 [21.4%] and 84 [10.1%], respectively [P 0.05). Adequate antenatal care, community education and raising awareness might decrease the number of teenage pregnancies, which was 13.6% in our study. © 2015 Japan Society of Obstetrics and Gynecology.
Jaffee, Kim D.; Perloff, Janet D.
2003-01-01
Explores the effects of ecological and individual risk factors on infant health for black and white women. Examines the association among neighborhood economic indicators, neighborhood quality, access to prenatal care, and individual perinatal risk factors and subsequent birthweight. The findings emphasize the need for socially and ecologically…
Velde, S.J. te; Twisk, J.W.R.; Mechelen, van W.; Kemper, H.C.G.
2005-01-01
OBJECTIVE: Investigating the relationship between birth weight and the metabolic syndrome and the modifying effects of lifestyle in adults (36.5 years). STUDY DESIGN AND SETTING: 273 subjects completed a birth-weight questionnaire; waist circumference, HDL and triglyceride concentrations, blood pres
Doyle, L; Anderson, P.; t and,
2005-01-01
Aim: To determine neurosensory outcome at 8 years of age of extremely low birthweight (ELBW) children born in the 1990s, how it varies with birth weight, and how it compares with ELBW children born in the 1980s and 1970s.
Weisglas-Kuperus, N.; Heersema, D. J.; Baerts, W.; Fetter, W. P. F.; Smrkovsky, M.; van Hof-van Duin, J.; Sauer, P. J. J.
1993-01-01
In order to determine the relationship between visual functions and neonatal cerebral ultrasound, neurological examinations and cognitive development, a prospective longitudinal study was conducted in 69 high-risk very-low-birthweight children. Visual development was studied at 1 and 2.6 years of co
Velde, S.J. te; Twisk, J.W.R.; Mechelen, van W.; Kemper, H.C.G.
2005-01-01
OBJECTIVE: Investigating the relationship between birth weight and the metabolic syndrome and the modifying effects of lifestyle in adults (36.5 years). STUDY DESIGN AND SETTING: 273 subjects completed a birth-weight questionnaire; waist circumference, HDL and triglyceride concentrations, blood
Somhovd, Mikael J.; Hansen, Bo M.; Brok, Jesper; Esbjorn, Barbara H.; Greisen, Gorm
2012-01-01
Aim: To determine if adolescents who are born very preterm (less than 32wks; of gestation) and/or with very low birthweight (VLBW; less than 1500g) have a higher risk of experiencing clinically significant anxiety problems. Method: We used a systematic review and meta-analysis. We searched the databases ISI Web of Knowledge, PubMed, PsycNET,…
Stockstill, Karen R.; Vogel, Thomas A.; Sisson, Thomas W.
2003-01-01
Burroughs Mountain, situated at the northeast foot of Mount Rainier, WA, exposes a large-volume (3.4 km 3) andesitic lava flow, up to 350 m thick and extending 11 km in length. Two sampling traverses from flow base to eroded top, over vertical sections of 245 and 300 m, show that the flow consists of a felsic lower unit (100 m thick) overlain sharply by a more mafic upper unit. The mafic upper unit is chemically zoned, becoming slightly more evolved upward; the lower unit is heterogeneous and unzoned. The lower unit is also more phenocryst-rich and locally contains inclusions of quenched basaltic andesite magma that are absent from the upper unit. Widespread, vuggy, gabbronorite-to-diorite inclusions may be fragments of shallow cumulates, exhumed from the Mount Rainier magmatic system. Chemically heterogeneous block-and-ash-flow deposits that conformably underlie the lava flow were the earliest products of the eruptive episode. The felsic-mafic-felsic progression in lava composition resulted from partial evacuation of a vertically-zoned magma reservoir, in which either (1) average depth of withdrawal increased, then decreased, during eruption, perhaps due to variations in effusion rate, or (2) magmatic recharge stimulated ascent of a plume that brought less evolved magma to shallow levels at an intermediate stage of the eruption. Pre-eruptive zonation resulted from combined crystallization-differentiation and intrusion(s) of less evolved magma into the partly crystallized resident magma body. The zoned lava flow at Burroughs Mountain shows that, at times, Mount Rainier's magmatic system has developed relatively large, shallow reservoirs that, despite complex recharge events, were capable of developing a felsic-upward compositional zonation similar to that inferred from large ash-flow sheets and other zoned lava flows.
Birth-weight, insulin levels, and HOMA-IR in newborns at term
Directory of Open Access Journals (Sweden)
Simental-Mendía Luis E
2012-07-01
Full Text Available Abstract Background Recent studies have demonstrated that low and high birth-weight at birth are risk factors of developing diabetes. The aim of this study was to determine if the abnormal birth-weight is related with hyperinsulinemia and elevated index of the Homeostasis Model assessment for Insulin Resistance (HOMA-IR at birth, in at term newborns. Methods Newborns with gestational age between 38 and 41 weeks, products of normal pregnancies of healthy mothers aged 18 to 39 years, were eligible to participate. Small-for-gestational age (SGA and large-for-gestational age (LGA newborns were compared with appropriate-for-gestational (AGA age newborns. Incomplete or unclear data about mother’s health status, diabetes, gestational diabetes, history of gestational diabetes, hypertension, pre-eclampsia, eclampsia, and other conditions that affect glucose metabolism were exclusion criteria. Hyperinsulinemia was defined by serum insulin levels ≥13.0 μU/mL and IR by HOMA-IR ≥2.60. Multiple logistic regression analysis was used to determine the odds ratio (OR that computes the association between birth-weight (independent variable with hyperinsulinemia and HOMA-IR index (dependent variables. Results A total of 107 newborns were enrolled; 13, 22, and 72 with SGA, LGA, and AGA, respectively. Hyperinsulinemia was identified in 2 (15.4%, 6 (27.3%, and 5 (6.9% with SGA, LGA, and AGA (p=0.03, whereas IR in 3 (23.1%, 8 (36.4%, and 10 (13.9% newborns with SGA, LGA and AGA (p=0.06. The LGA showed a strong association with hyperinsulinemia (OR 5.02; CI 95%, 1.15-22.3; p=0.01 and HOMA-IR (OR 3.54; CI 95%, 1.03-12.16; p=0.02; although without statistical significance, the SGA showed a tendency of association with hyperinsulinemia (OR 2.43; CI 95%, 0.43-17.3 p=0.29 and HOMA-IR (OR 1.86; CI 95%, 0.33-9.37; p=0.41. Conclusions Our results suggest that LGA is associated with hyperinsulinemia and elevated HOMA-IR at birth whereas the SGA show a tendency of
van Kooij, Britt J. M.; Benders, Manon J. N. L.; Anbeek, Petronella; van Haastert, Ingrid C.; de Vries, Linda S.; Groenendaal, Floris
2012-01-01
Aim: To assess the relation between cerebellar volume and spectroscopy at term equivalent age, and neurodevelopment at 24 months corrected age in preterm infants. Methods: Magnetic resonance imaging of the brain was performed around term equivalent age in 112 preterm infants (mean gestational age 28wks 3d [SD 1wk 5d]; birthweight 1129g [SD 324g]).…
van Kooij, Britt J. M.; Benders, Manon J. N. L.; Anbeek, Petronella; van Haastert, Ingrid C.; de Vries, Linda S.; Groenendaal, Floris
2012-01-01
Aim: To assess the relation between cerebellar volume and spectroscopy at term equivalent age, and neurodevelopment at 24 months corrected age in preterm infants. Methods: Magnetic resonance imaging of the brain was performed around term equivalent age in 112 preterm infants (mean gestational age 28wks 3d [SD 1wk 5d]; birthweight 1129g [SD 324g]).…
Wen, Li Ming; Simpson, Judy M; Rissel, Chris; Baur, Louise A
2013-03-01
A high infant birthweight is associated with future risk of a range of adverse health consequences. This study sought to determine whether maternal "junk food" diet (energy-dense, nutrient-poor) predicts high birthweight in first-time mothers in southwest Sydney, Australia. A community-based longitudinal study was conducted with a total of 368 first-time mothers and their newborns. Information about maternal "junk food" diet, including high consumption of soft drink, fast food, and/or processed meat and chips, and self-reported prepregnant weight and height of first-time mothers was collected by a face-to-face interview with mothers between 24 and 34 weeks of pregnancy. Birthweight was measured in hospital and reported by the mother, together with gestational age, when the baby was 6 months old. Logistic regression modeling was used to determine the factors predicting birthweight greater than 4.0 kg. Eleven percent of newborns weighed more than 4.0 kg (12% boys, 9% girls). Compared with mothers who had a "junk food" diet, mothers who had not consumed "junk food" during pregnancy were significantly less likely to have a newborn weighing more than 4.0 kg, with adjusted odds ratio (AOR) 0.36, 95 percent confidence interval (CI) 0.14-0.91, p = 0.03, after adjusting for maternal weight status and gestational age. Compared with healthy and underweight mothers, overweight or obese mothers were more likely to have a newborn weighing more than 4.0 kg (AOR overweight 3.03, 95% CI 1.35-6.80; obese 3.79, 95% CI 1.41-10.25) after allowing for "junk food" diet and gestational age. Maternal "junk food" diet during pregnancy and prepregnant overweight and obesity were independent predictors of high infant birthweight. Early childhood obesity interventions should consider addressing these factors. © 2013, Copyright the Authors Journal compilation © 2013, Wiley Periodicals, Inc.
CSIR Research Space (South Africa)
Heyns, Johan A
2013-05-01
Full Text Available of the gas has a noteworthy effect on predicted pressure loads in liquid–gas flow in certain instances. With the aim of providing a more accurate numerical representation of dynamic two-fluid flow, the solver is subsequently extended to account for variations...
DEFF Research Database (Denmark)
Hilsted, J; Bonde-Petersen, F; Madsbad, S
1985-01-01
and transcapillary escape rate increased significantly during hypoglycaemia. Skin temperature and local subcutaneous adipose tissue blood flow were measured in four different regions. Both tended to decrease during hypoglycaemia and decreased significantly 2 h after hypoglycaemia. There was no correlation between...... changes in the two measurements, suggesting that there is no simple relationship between subcutaneous blood flow and skin temperature during hypoglycaemia....
Harms, M.P.M.; Wesseling, K.H.; Pott, F.; Jenstrup, M.; Goudoever, J. van; Secher, N.H.; Lieshout, J.J. van
1999-01-01
The relationship between aortic flow and pressure is described by a three-element model of the arterial input impedance, including continuous correction for variations in the diameter and the compliance of the aorta (Modelflow). We computed the aortic flow from arterial pressure by this model, and
Adipose tissue transcriptomics and epigenomics in low birthweight men and controls
DEFF Research Database (Denmark)
Gillberg, Linn; Perfilyev, Alexander; Brøns, Charlotte
2016-01-01
Aims/hypothesis: Individuals who had a low birthweight (LBW) are at an increased risk of insulin resistance and type 2 diabetes when exposed to high-fat overfeeding (HFO). We studied genome-wide mRNA expression and DNA methylation in subcutaneous adipose tissue (SAT) after 5 days of HFO and after...... in CDK5, IGFBP5 and SLC2A4) was altered in SAT after overfeeding in this and in another cohort. Conclusions/interpretation: Young men who had a LBW exhibit epigenetic alterations in their adipose tissue that potentially influence insulin resistance and risk of type 2 diabetes. Short-term overfeeding...... influences gene transcription and, to some extent, DNA methylation in adipose tissue; there was no major difference in this response between LBW and control participants....
Chernozhukov, Victor
2009-01-01
Quantile regression is an increasingly important empirical tool in economics and other sciences for analyzing the impact of a set of regressors on the conditional distribution of an outcome. Extremal quantile regression, or quantile regression applied to the tails, is of interest in many economic and financial applications, such as conditional value-at-risk, production efficiency, and adjustment bands in (S,s) models. In this paper we provide feasible inference tools for extremal conditional quantile models that rely upon extreme value approximations to the distribution of self-normalized quantile regression statistics. The methods are simple to implement and can be of independent interest even in the non-regression case. We illustrate the results with two empirical examples analyzing extreme fluctuations of a stock return and extremely low percentiles of live infants' birthweights in the range between 250 and 1500 grams.
Accuracy and correlates of maternal recall of birthweight and gestational age
DEFF Research Database (Denmark)
Adegboye, A R A; Heitmann, Berit Lilienthal
2008-01-01
OBJECTIVE: To determine the accuracy of maternal recall of children birthweight (BW) and gestational age (GA), using the Danish Medical Birth Register (DBR) as reference and to examine the reliability of recalled BW and its potential correlates. DESIGN: Comparison of data from the DBR...... and the European Youth Heart Study (EYHS). SETTING: Schools in Odense, Denmark. POPULATION: A total of 1271 and 678 mothers of school children participated with information in the accuracy studies of BW and GA, respectively. The reliability sample of BW was composed of 359 women. METHOD: The agreement between...... the two sources was evaluated by mean differences (MD), intraclass correlation coefficient (ICC) and Bland-Altman's plots. The misclassification of the various BW and GA categories were also estimated. MAIN OUTCOME MEASURES: Differences between recalled and registered BW and GA. RESULTS: There was high...
Reduced infant birthweight consequent upon maternal exposure to severe life events
DEFF Research Database (Denmark)
Khashan, Ali; McNamee, R.; Pedersen, Marianne Giørtz
2008-01-01
). There was a significant association between maternal exposure to death of a relative and risk of a baby weighing below the 10th percentile (adjusted relative risk (RR) = 1.17, 95% CI = 1.13, 1.22) and 5th percentile (adjusted RR = 1.22, 95% CI = 1.15, 1.29). CONCLUSIONS: Mothers exposed to severe life events before......OBJECTIVE: To investigate the association between maternal exposure to severe life events and fetal growth (birthweight and small for gestational age). Stress has been associated with adverse pregnancy outcome. METHODS: Mothers of 1.38 million singleton live births in Denmark between January 1......, 1979 and December 31, 2002 were linked to information on their spouses, parents, siblings, and older children. Exposure was defined as death or serious illness in a relative during pregnancy or in the 6 months before conception. Linear regression was used to examine the effect of exposure...
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Omid Ali Akbari
2015-11-01
Full Text Available This article aims to study the impact of ribs on flow parameters and laminar heat transfer of water–aluminum oxide nanofluid with different nanoparticle volume fractions in a three-dimensional rectangular microchannel. To this aim, compulsory convection heat transfer of water–aluminum oxide nanofluid in a rib-roughened microchannel has been numerically studied. The results of this simulation for rib-roughened three-dimensional microchannel have been evaluated in contrast to the smooth (unribbed three-dimensional microchannel with identical geometrical and heat–fluid boundary conditions. Numerical simulation is performed for different nanoparticle volume fractions for Reynolds numbers of 10 and 100. Cold fluid entering the microchannel is heated in order to apply constant flux to external surface of the microchannel walls and then leaves it. Given the results, the fluid has a higher heat transfer with a hot wall in surfaces with ribs rather than in smooth ones. As Reynolds number, number of ribs, and nanoparticle volume fractions increase, more temperature increase happens in fluid in exit intersection of the microchannel. By investigating Nusselt number and friction factor, it is observed that increase in nanoparticle volume fractions causes nanofluid heat transfer properties to have a higher heat transfer and friction factor compared to the base fluid used in cooling due to an increase in viscosity.
Energy Technology Data Exchange (ETDEWEB)
Abolmaali, Nasreddin; Koch, Arne [Dresden University of Technology, OncoRay - Molecular and Biological Imaging, Medical Faculty Carl Gustav Carus, Dresden (Germany); Goetzelt, Knut; Vogelberg, Christian [University Clinics Carl Gustav Carus, Dresden University of Technology, Clinic and Policlinic for Pediatrics - Pediatric Pulmonology, Dresden (Germany); Hahn, Gabriele [University Clinics Carl Gustav Carus, Dresden University of Technology, Institute and Policlinic for Radiology - Pediatric Radiology, Dresden (Germany); Fitze, Guido [University Clinics Carl Gustav Carus, Dresden University of Technology, Clinic and Policlinic for Pediatric Surgery, Dresden (Germany)
2010-07-15
To compare MRI-based functional pulmonary and cardiac measurements in the long-term follow-up of children operated on for left-sided congenital diaphragmatic hernia (CDH) with age- and body size-matched healthy controls. Twelve children who received immediate postnatal surgery for closure of isolated left-sided CDH were included and received basic medical examinations, pulmonary function testing and echocardiography. MRI included measurement of lung volume, ventricular function assessment and velocity-encoded imaging of the pulmonary arteries and was compared with the data for 12 healthy children matched for age and body size. While patients' clinical test results were not suspicious, comparison between the MRI data for patients and those for healthy controls revealed significant differences. In patients, the volumes of the left lungs were increased and the tidal volume was larger on the right side. While the stroke volumes of both ventricles were reduced, heart rate and ejection fraction were increased. Flow, acceleration time and cross-sectional area of the left pulmonary artery were reduced. Functional MRI detected pulmonary and cardiac findings in the late follow-up of CDH children which may be missed by standard clinical methods and might be relevant for decisions regarding late outcome and treatment. (orig.)
Risk factors for low birthweight in the public-hospitals at Peshawar, NWFP-Pakistan
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Payne Roger
2008-06-01
Full Text Available Abstract Background Low birthweight is a widely used indicator of newborn health. This study investigates the association of birthweight Methods Data on geo-demographics, maternal health indicators, pregnancy history and outcome scores for newborn babies and their families (n = 1039 were collected prospectively between August and November 2003 in a cross-sectional survey of four public hospitals in Peshawar, NWFP-Pakistan. Crude and adjusted odds ratios were used to investigate the factors affecting incidence of LBW, by multivariate logistic regression. Gestational age was included as an explanatory variable therefore the additional covariates identified by model selection are expected to account for SGA. Results The main geo-demographic risk factors for SGA identified in this study, controlling for gestational age of less than 37 weeks, are maternal age, nationality and consanguinity. Presentation with anaemia and the history of previous abortion/miscarriage were also found to be significant independent factors. The adjusted odds ratio for gestational age showed the largest effect in explaining the incidence of LBW. The next highest odds ratio was for maternal age below 20 years. The explanatory model included two pairwise interactions, for which the predicted incidence figures for LBW show an increase among the Tribal area with presentation of anaemia, and among full term babies with their mothers having a previous history of abortion/miscarriage. Conclusion In addition to gestational age, specific factors related to geo-demographics (maternal age, consanguinity and nationality, maternal health (anaemia and pregnancy history (abortion/miscarriage were significantly associated with the incidence of LBW observed at the four hospitals surveyed in Peshawar. These results indicate that cultural factors can adversely affect the incidence of SGA in this area of Pakistan.
Mental Health Outcomes in US Children and Adolescents Born Prematurely or with Low Birthweight
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Gopal K. Singh
2013-01-01
Full Text Available We examined the effects of prematurity (37 weeks of gestation and low birthweight (2500 g on mental health outcomes among US children aged 2–17 years. The 2011-2012 National Survey of Children’s Health ( = 95,677 was used to estimate prevalence of parent-reported mental health problems in children. Prevalence of mental disorders was 22.9% among children born prematurely, 28.7% among very-low-birth-weight (1500 g children, and 18.9% among moderately low-birth-weight (1500–2499 g children, compared with 15.5% in the general child population. Compared to those born full term, children born prematurely had 61% higher adjusted odds of serious emotional/behavioral problems, 33% higher odds of depression, and 58% higher odds of anxiety. Children born prematurely had 2.3 times higher odds of autism/ASD, 2.9 times higher odds of development delay, and 2.7 times higher odds of intellectual disability than term children. Very-low-birth-weight children had 3.2 times higher odds of autism/ASD, 1.7 times higher odds of ADD/ADHD, 5.4 times higher odds of development delay, and 4.4 times higher odds of intellectual disability than normal-birth-weight children. Social factors were significant predictors of mental disorders in both premature/low-birth-weight and term/normal-birth-weight children. Neurodevelopmental conditions accounted for the relationship between prematurity and depression/anxiety/conduct problems. Prematurity and low birthweight are significant risk factors for mental health problems among children.
Cardiac surgery of premature and low birthweight newborns: is a change of fate possible?
Alkan-Bozkaya, Tijen; Türkoğlu, Halil; Akçevin, Atif; Paker, Tufan; Ozkan-Çerçi, Hilda; Dindar, Aygün; Ersoy, Cihangir; Bayer, Vedat; Aşkin, Demet; Undar, Akif
2010-11-01
Low birthweight (LBW) continues to be a high-risk factor in surgery for congenital heart disease. This risk is particularly very high in very low birthweight infants under 1500g and extremely LBW infants under 1000g. From January 2005 to December 2008, 33 consecutive LBW neonates underwent cardiac surgery in our clinic in keeping with the criteria for choice of surgery. Their weight range was between 800 and 1900g. Nine of them were under 1000g. Cardiopulmonary bypass (CPB) was used in 17 patients (39.5%) and pulsatile perfusion mode was applied to patients in the CPB group. The same surgical team operated to achieve palliation (8 patients, 24.2%) or full repair (25 patients, 75.8%). Median gestational age was 36 weeks with 12 (36.4%) premature babies (≤37 weeks). Median age at operation was 5 days. Pathologies were single ventricle (n=3), pulmonary atresia-ventricular septal defect (n=3), aortic coarctation (n=10), aorticopulmonary window and interrupted aortic arch combination (n=6), patent arterial duct (n=11), critical aortic stenosis (n=8), and tetralogy of Fallot with pulmonary atresia (n=2). One infant had VATER syndrome. Selective cerebral perfusion technique was used in complex arch pathologies for cerebral protection. Median follow-up was 14 months. There were four early postoperative deaths. None of the cases showed a need for early reoperation. The acceptable early- and midterm mortality rates in this group suggest that these operations can be successfully performed. There is a need for further multicenter studies to evaluate these high-risk groups.
Influence of a combination of probiotics on bacterial infections in very low birthweight newborns.
Kanic, Zlatka; Micetic Turk, Dusanka; Burja, Silva; Kanic, Vojko; Dinevski, Dejan
2015-12-01
Late-onset infections are an important cause of morbidity and mortality in preterm infants. The purpose of our prospective randomised study was to establish whether a combination of probiotics (Lactobacillus acidophilus, Enterococcus faecium and Bifidobacterium infantum) affects the incidence of late-onset sepsis and other infections in very low birthweight infants (birthweight under 1500 g, gestational age under 33 weeks). From 80 included infants, one half received probiotics (L. acidophilus, E. faecium and B. infantum) in the ratio 1.5:1:1.5, at a dose of 0.6 × 107 colony-forming units twice daily, given with the first portions of milk until discharge, whereas the other half did not. In the group receiving probiotics, 16 children had late-onset sepsis compared with 29 in the group without probiotics; p = 0.006. The number of late-onset septic events was lower (30) in the group receiving probiotics than in the group that did not receive probiotics (69); p = 0.003. Furthermore, fewer children had at least one late-onset infection (20 infants in the group receiving probiotics compared with 32 in the group without them; p = 0.009). There were less episodes of late-onset infections in the group receiving probiotics (35) than in the group without probiotics (79); p = 0.002. A combination of probiotics at a low dose (1.2 × 107 colony-forming units) decreased the frequency of late-onset sepsis and other infections, as described in previous studies. In addition, children were discharged at a lower postmenstrual age. There were no side effects of probiotics reported.
Kandasamy, R.; Jeyabalan, C.; Sivagnana Prabhu, K. K.
2016-02-01
This article examines the influence of thermophoresis, Brownian motion of the nanoparticles with variable stream conditions in the presence of magnetic field on mixed convection heat and mass transfer in the boundary layer region of a semi-infinite porous vertical plate in a nanofluid under the convective boundary conditions. The transformed boundary layer ordinary differential equations are solved numerically using Maple 18 software with fourth-fifth order Runge-Kutta-Fehlberg method. Numerical results are presented both in tabular and graphical forms illustrating the effects of these parameters with magnetic field on momentum, thermal, nanoparticle volume fraction and solutal concentration boundary layers. The numerical results obtained for the velocity, temperature, volume fraction, and concentration profiles reveal interesting phenomenon, some of these qualitative results are presented through plots. It is interesting to note that the magnetic field plays a dominant role on nanofluid flow under the convective boundary conditions.
Salinas, P.; Jackson, M.; Pavlidis, D.; Pain, C.; Adam, A.; Xie, Z.; Percival, J. R.
2015-12-01
We present a new, high-order, control-volume-finite-element (CVFE) method with discontinuous representation for pressure and velocity to simulate multiphase flow in heterogeneous porous media. Time is discretized using an adaptive, fully implicit method. Heterogeneous geologic features are represented as volumes bounded by surfaces. Within these volumes, termed geologic domains, the material properties are constant. A given model typically contains numerous such geologic domains. Our approach conserves mass and does not require the use of CVs that span domain boundaries. Computational efficiency is increased by use of dynamic mesh optimization, in which an unstructured mesh adapts in space and time to key solution fields, such as pressure, velocity or saturation, whilst preserving the geometry of the geologic domains. Up-, cross- or down-scaling of material properties during mesh optimization is not required, as the properties are uniform within each geologic domain. We demonstrate that the approach, amongst other features, accurately preserves sharp saturation changes associated with high aspect ratio geologic domains such as fractures and mudstones, allowing efficient simulation of flow in highly heterogeneous models. Moreover, accurate solutions are obtained at significantly lower computational cost than an equivalent fine, fixed mesh and conventional CVFE methods. The use of implicit time integration allows the method to efficiently converge using highly anisotropic meshes without having to reduce the time-step. The work is significant for two key reasons. First, it resolves a long-standing problem associated with the use of classical CVFE methods to model flow in highly heterogeneous porous media, in which CVs span boundaries between domains of contrasting material properties. Second, it reduces computational cost/increases solution accuracy through the use of dynamic mesh optimization and time-stepping with large Courant number.
During a series of painting operations in a horizontal-flow paint spray booth at Travis AFB, CA, baseline concentrations of four classes of toxic airborne pollutants were measured at 24 locations across a plane immediately forward of the exhaust filters, in the exhaust duct, and ...
Directory of Open Access Journals (Sweden)
Scott J Butcher
2007-01-01
Full Text Available BACKGROUND: The effectiveness of high-frequency chest wall oscillation (HFCWO in mucolysis and mucous clearance is thought to be dependant on oscillatory flow rate (Fosc. Therefore, increasing Fosc during HFCWO may have a clinical benefit.
Egidi, Nadaniela; Giacomini, Josephin; Maponi, Pierluigi
2016-06-01
Matter of this paper is the study of the flow and the corresponding heat transfer in a U-shaped heat exchanger. We propose a mathematical model that is formulated as a forced convection problem for incompressible and Newtonian fluids and results in the unsteady Navier-Stokes problem. In order to get a solution, we discretise the equations with both the Finite Elements Method and the Finite Volumes Method. These procedures give rise to a non-symmetric indefinite quadratic system of equations. Thus, three regularisation techniques are proposed to make approximations effective and ideas to compare their results are provided.
Energy Technology Data Exchange (ETDEWEB)
Salmon, R.; Edwards, M.S.; Ulrich, W.C.
1977-06-01
This volume consists of individual block flowsheets for the various units of the Synthoil facility, showing the overall flows into and out of each unit. Material balances for the following units are incomplete because these are proprietary processes and the information was not provided by the respective vendors: Unit 24-Claus Sulfur Plant; Unit 25-Oxygen Plant; Unit 27-Sulfur Plant (Redox Type); and Unit 28-Sour Water Stripper and Ammonia Recovery Plant. The process information in this form was specifically requested by ERDA/FE for inclusion in the final report.
Fox, S. R.; Smetana, F. O.
1980-01-01
The listings, user's instructions, sample inputs, and sample outputs of two computer programs which are especially useful in obtaining an approximate solution of the viscous flow over an arbitrary nonlifting three dimensional body are provided. The first program performs a potential flow solution by a well known panel method and readjusts this initial solution to account for the effects of the boundary layer displacement thickness, a nonuniform but unidirectional onset flow field, and the presence of air intakes and exhausts. The second program is effectually a geometry package which allows the user to change or refine the shape of a body to satisfy particular needs without a significant amount of human intervention. An effort to reduce the cruise drag of light aircraft through an analytical study of the contributions to the drag arising from the engine cowl shape and the foward fuselage area and also that resulting from the cooling air mass flowing through intake and exhaust sites on the nacelle is presented. The programs may be effectively used to determine the appropriate body modifications or flow port locations to reduce the cruise drag as well as to provide sufficient air flow for cooling the engine.
Energy Technology Data Exchange (ETDEWEB)
Jamieson, Bob; Braatne, Jeffrey H.
2001-10-01
Riparian vegetation and especially cottonwood and willow plant communities are dependent on normative flows and especially, spring freshette, to provide conditions for recruitment. These plant communities therefore share much in common with a range of fish species that require natural flow conditions to stimulate reproduction. We applied tools and techniques developed in other areas to assess riparian vegetation in two very different sub-basins within the Columbia Basin. Our objectives were to: Document the historic impact of human activity on alluvial floodplain areas in both sub-basins; Provide an analysis of the impacts of flow regulation on riparian vegetation in two systems with very different flow regulation systems; Demonstrate that altered spring flows will, in fact, result in recruitment to cottonwood stands, given other land uses impacts on each river and the limitations imposed by other flow requirements; and Assess the applicability of remote sensing tools for documenting the distribution and health of cottonwood stands and riparian vegetation that can be used in other sub-basins.
Energy Technology Data Exchange (ETDEWEB)
Jamieson, Bob; Braatne, Jeffrey H.
2001-10-01
Riparian vegetation and especially cottonwood and willow plant communities are dependent on normative flows and especially, spring freshette, to provide conditions for recruitment. These plant communities therefore share much in common with a range of fish species that require natural flow conditions to stimulate reproduction. We applied tools and techniques developed in other areas to assess riparian vegetation in two very different sub-basins within the Columbia Basin. Our objectives were to: Document the historic impact of human activity on alluvial floodplain areas in both sub-basins; Provide an analysis of the impacts of flow regulation on riparian vegetation in two systems with very different flow regulation systems; Demonstrate that altered spring flows will, in fact, result in recruitment to cottonwood stands, given other land uses impacts on each river and the limitations imposed by other flow requirements; and Assess the applicability of remote sensing tools for documenting the distribution and health of cottonwood stands and riparian vegetation that can be used in other sub-basins.
Sebayang, Susy K; Dibley, Michael J; Kelly, Patrick J; Shankar, Anita V; Shankar, Anuraj H
2012-08-01
To examine the determinants of low birthweight (LBW), small-for-gestation (SGA) and preterm births in Lombok, Indonesia, an area of high infant mortality. Data from The Supplementation with Multiple Micronutrient Intervention Trial (SUMMIT), a double-blind cluster-randomised controlled trial, were analysed. The odds ratio of factors known to be associated with LBW, SGA and preterm birth was assessed and adjusted for the cluster design of the trial using hierarchical logistic regression. Determinants included constitutional, demographic and psychosocial factors, toxic exposure, maternal nutrition and obstetric history and maternal morbidity during and prior to pregnancy. Population attributable risks of modifiable determinants were calculated. A cohort of 14,040 singleton births was available for analysis of LBW, with 13,498 observations for preterm births and 13,461 for SGA births. Determinants of LBW and SGA were similar and included infant's sex, woman's education, season at birth, mothers' residence, household wealth, maternal mid-upper arm circumference (MUAC), height and a composite variable of birth order and pregnancy interval. Socioeconomic indicators were also related to preterm births and included mother's education, residence and household wealth, while nutritional-related factors including low MUAC and birth order and interval were associated with preterm birth but not maternal height. Nausea was protective of preterm birth, while diarrhoea was associated with higher odds of preterm birth. Oedema during pregnancy was protective of SGA but associated with higher odds of preterm delivery. Around 33%, 13% and 13% of the determinants of LBW, SGA and preterm births were preventable. Women's education, maternal nutrition and household wealth and family planning are key factors to improving birth outcomes. © 2012 Blackwell Publishing Ltd.
DEFF Research Database (Denmark)
Lida, H; Law, I; Pakkenberg, B
2000-01-01
formulated four mathematical models that describe the dynamic behavior of a freely diffusible tracer (H215O) in a region of interest (ROI) incorporating estimates of regional tissue flow that are independent of PVE. The current study was intended to evaluate the feasibility of these models and to establish...... a methodology to accurately quantify regional cerebral blood flow (CBF) corrected for PVE in cortical gray matter regions. Five monkeys were studied with PET after IV H2(15)O two times (n = 3) or three times (n = 2) in a row. Two ROIs were drawn on structural magnetic resonance imaging (MRI) scans and projected...... onto the PET images in which regional CBF values and the water perfusable tissue fraction for the cortical gray matter tissue (hence the volume of gray matter) were estimated. After the PET study, the animals were killed and stereologic analysis was performed to assess the gray matter mass...
DEFF Research Database (Denmark)
Thomsen, H; Steffensen, E; Larsson, Elna-Marie
2012-01-01
technique arterial spin labelling (ASL) presently provides measurement only of cerebral blood flow (CBF), which has not been widely used in human brain tumor studies. Purpose: To assess if measurement of blood flow is comparable with measurement of blood volume in human biopsy-proven gliomas obtained by DSC......, and glioblastomas. Results: rCBF and rCBV measurements obtained with the maximum perfusion method were correlated when normalized to white matter (r ¼ 0.60) and to the cerebellum (r ¼ 0.49). Histogram analyses of rCBF and rCBV showed that mean and median values as well as skewness and peak position were correlated......-MRI using two different regions for normalization and two different measurement approaches. Material and Methods: Retrospective study of 61 patients with different types of gliomas examined with DSC perfusion MRI. Regions of interest (ROIs) were placed in tumor portions with maximum perfusion on rCBF and r...
Directory of Open Access Journals (Sweden)
Bálint Várkuti
Full Text Available BACKGROUND: In the graph theoretical analysis of anatomical brain connectivity, the white matter connections between regions of the brain are identified and serve as basis for the assessment of regional connectivity profiles, for example, to locate the hubs of the brain. But regions of the brain can be characterised further with respect to their gray matter volume or resting state perfusion. Local anatomical connectivity, gray matter volume and perfusion are traits of each brain region that are likely to be interdependent, however, particular patterns of systematic covariation have not yet been identified. METHODOLOGY/PRINCIPAL FINDINGS: We quantified the covariation of these traits by conducting an integrative MRI study on 23 subjects, utilising a combination of Diffusion Tensor Imaging, Arterial Spin Labeling and anatomical imaging. Based on our hypothesis that local connectivity, gray matter volume and perfusion are linked, we correlated these measures and particularly isolated the covariation of connectivity and perfusion by statistically controlling for gray matter volume. We found significant levels of covariation on the group- and regionwise level, particularly in regions of the Default Brain Mode Network. CONCLUSIONS/SIGNIFICANCE: Connectivity and perfusion are systematically linked throughout a number of brain regions, thus we discuss these results as a starting point for further research on the role of homology in the formation of functional connectivity networks and on how structure/function relationships can manifest in the form of such trait interdependency.
On the effect of standard PFEM remeshing on volume conservation in free-surface fluid flow problems
Franci, Alessandro; Cremonesi, Massimiliano
2017-07-01
The aim of this work is to analyze the remeshing procedure used in the particle finite element method (PFEM) and to investigate how this operation may affect the numerical results. The PFEM remeshing algorithm combines the Delaunay triangulation and the Alpha Shape method to guarantee a good quality of the Lagrangian mesh also in large deformation processes. However, this strategy may lead to local variations of the topology that may cause an artificial change of the global volume. The issue of volume conservation is here studied in detail. An accurate description of all the situations that may induce a volume variation during the PFEM regeneration of the mesh is provided. Moreover, the crucial role of the parameter α used in the Alpha Shape method is highlighted and a range of values of α for which the differences between the numerical results are negligible, is found. Furthermore, it is shown that the variation of volume induced by the remeshing reduces by refining the mesh. This check of convergence is of paramount importance for the reliability of the PFEM. The study is carried out for 2D free-surface fluid dynamics problems, however the conclusions can be extended to 3D and to all those problems characterized by significant variations of internal and external boundaries.
Beneventi, Fausta; Locatelli, Elena; Giorgiani, Giovanna; Zecca, Marco; Mina, Tommaso; Simonetta, Margherita; Cavagnoli, Chiara; Albanese, Mara; Spinillo, Arsenio
2015-02-01
To compare uterine and ovarian volumes and uterine artery (UA) Doppler blood flow among women who were treated with antineoplastic regimens when pediatric aged versus healthy controls. Case-control study. Tertiary obstetric and gynecologic center. One hundred twenty-seven women who were treated for childhood cancer with bone marrow transplantation (BMT) and∖or chemotherapy and total body irradiation (TBI) and 64 age-matched healthy controls. Ultrasonographic and clinical evaluations. Uterine and ovarian volume, detection of follicles, and UA pulsatility index (PI). Median uterus and ovarian volumes were reduced by 64% (95% CI, 56.6-70.6) and 83.6% (95% CI, 79.6-86.7), respectively, among cases compared with controls. Median UA PI among cases was increased by 30.3% (95% CI, 19.6-40.8) compared with controls. Ovarian follicles were identified in 24 (18.9%) of 127 cases and 25 (39%) of 64 controls. Uterine volume was reduced after TBI (percent reduction 81.9%; 95% CI, 71.8-87.8) or busulfan (percentage reduction 67.4%; 95% CI, 58.5-75.6) compared with those who had not received a conditioning regimen (percentage reduction 24.4%; 95% CI, 7.6-38.2). The only factors independently associated with reduced uterine and ovarian volumes compared with controls were TBI, busulfan, and BMT. The worst effect on UA PI resulted from BMT and a diagnosis of hematologic disease. Bone marrow transplantation as main treatment and TBI and busulfan as conditioning regimens had the worst effect on uterine and ovarian sizes compared with controls. These data should be considered in counseling families on preserving future fertility in children undergoing BMT. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.
Okamura, H
1976-01-01
A pyrex glass plate was fitted at the bottom of casting ring, and disk type wax pattern (thickness. 0.43 mm) was put on the plate. Five types of sprueing were applied. Pure tin was casted using holizontal centrifugal casting machine. Flow of molten metal was filmed by the motor drive camera with the method of stroboscope. The results were summarized as follows. 1) When the sprue was attached at the center of the disk type mold vertically, moten metal flowed like a concentric circle at the early stage of casting. It was affected gradually by the direction of gravity and revolution, and it filled the mold from the lower part to the upper part. 2) When the sprue gate was attached to the side edge of the mold, and the sprue gate was placed to the forward and backward direction against the revolution direction, molten metal filled from lower part to the upper part. 3) When the sprue gate was placed against upper edge, molten metal flow was affected by the direction of gravity and revolution. When the sprue gate was placed against lower edge, molten metal filled quietry from the lower part to the upper part. 4) Inflow volume per unit time (inflow rate) was small at the early stage of casting. Inflow rate increased and became constant at the next stage. At the latter stage it became small again. 5) Inflow rate increased with the increase of area of sprue. 6) The time which was necessary to fill the volume of 1 cm (about 80% of the mold volume) became short with the increase of area of sprue. It was also influenced by the type of sprueing.
Martyr-Koller, R.C.; Kernkamp, H.W.J.; Van Dam, Anne A.; Mick van der Wegen,; Lucas, Lisa; Knowles, N.; Jaffe, B.; Fregoso, T.A.
2017-01-01
A linked modeling approach has been undertaken to understand the impacts of climate and infrastructure on aquatic ecology and water quality in the San Francisco Bay-Delta region. The Delft3D Flexible Mesh modeling suite is used in this effort for its 3D hydrodynamics, salinity, temperature and sediment dynamics, phytoplankton and water-quality coupling infrastructure, and linkage to a habitat suitability model. The hydrodynamic model component of the suite is D-Flow FM, a new 3D unstructured finite-volume model based on the Delft3D model. In this paper, D-Flow FM is applied to the San Francisco Bay-Delta to investigate tidal, seasonal and annual dynamics of water levels, river flows and salinity under historical environmental and infrastructural conditions. The model is driven by historical winds, tides, ocean salinity, and river flows, and includes federal, state, and local freshwater withdrawals, and regional gate and barrier operations. The model is calibrated over a 9-month period, and subsequently validated for water levels, flows, and 3D salinity dynamics over a 2 year period.Model performance was quantified using several model assessment metrics and visualized through target diagrams. These metrics indicate that the model accurately estimated water levels, flows, and salinity over wide-ranging tidal and fluvial conditions, and the model can be used to investigate detailed circulation and salinity patterns throughout the Bay-Delta. The hydrodynamics produced through this effort will be used to drive affiliated sediment, phytoplankton, and contaminant hindcast efforts and habitat suitability assessments for fish and bivalves. The modeling framework applied here will serve as a baseline to ultimately shed light on potential ecosystem change over the current century.
DEFF Research Database (Denmark)
Petersen, Inge; Jensen, Vibeke Myrup; McGue, Matt
2009-01-01
of controlling for both unmeasured common childhood-environmental factors as well as genetic factors shared by the co-twins. Two twin studies suggest the existence of genetic mediation between birthweight and IQ, that is, common genetic factors influence both fetal growth and IQ in childhood, while two other......Abstract Evidence of a positive association between birthweight and IQ has been established in several studies. Analyses of within twin pair differences in birthweight and IQ have been used to shed light on the basis of the association. The strength of this approach is the possibility...... twin studies find no evidence of such mediation. In the present study we use a large population-based national register study of 2,413 Danish twin-pairs from birth cohorts 1986-1990, of which we have zygosity information on 74%. We perform individual level as well as intra-pair analyses of birthweight...
Karelsky, K V; Slavin, A G
2011-01-01
The numerical method for study of hydrodynamic flows over an arbitrary bed profile in the presence of external force is proposed in this paper. This method takes into account the external force effect, it uses the quasi-two-layer model of hydrodynamic flows over a stepwise boundary with consideration of features of the flow near the step. A distinctive feature of the proposed method is the consideration of the properties of the process of the waterfall, namely the fluid flow on the step in which the fluid does not wet part of the vertical wall of the step. The presence of dry zones in the vertical part of the step indicates violation of the conditions of hydrostatic flow. The quasi-two-layer approach allows to determine the size of the dry zone of the vertical component of the step. Consequently it gives an opportunity to figure out the amount of kinetic energy dissipation. There are performed the numerical simulations based on the proposed algorithm of various physical phenomena, such as a breakdown of the r...
1995-01-01
A computational fluid dynamics (CFD) analysis has been performed on the aft slot region of the Titan 4 Solid Rocket Motor Upgrade (SRMU). This analysis was performed in conjunction with MSFC structural modeling of the propellant grain to determine if the flow field induced stresses would adversely alter the propellant geometry to the extent of causing motor failure. The results of the coupled CFD/stress analysis have shown that there is a continual increase of flow field resistance at the aft slot due to the aft segment propellant grain being progressively moved radially toward the centerline of the motor port. This 'bootstrapping' effect between grain radial movement and internal flow resistance is conducive to causing a rapid motor failure.
Forghani-Tehrani, Pezhman; Karimipour, Arash; Afrand, Masoud; Mousavi, Sayedali
2017-01-01
Nanofluid flow and heat transfer composed of water-silver nanoparticles is investigated numerically inside a microchannel. Finite volume approach (FVM) is applied and the effects of gravity are ignored. The whole length of Microchannel is considered in three sections as l1=l3=0.151 and l2=0.71. The linear variable heat flux affects the microchannel wall in the length of l2 while a magnetic field with strength of B0 is considered over the whole domain of it. The influences of different values of Hartmann number (Ha=0, 10, 20), volume fraction of the nanoparticles (ɸ=0, 0.02, 0.04) and Reynolds number (Re=10, 50, 200) on the hydrodynamic and thermal properties of flow are reported. The investigation of slip velocity variations under the effects of a magnetic field are presented for the first time (to the best knowledge of author) while the non-dimensional slip coefficient are selected as B=0.01, 0.05, 0.1 at different states.
2003-10-01
aspects of Volume 1 and 2 of the original Flight Test Manual , including the flight testing of aircraft systems. The monographs in this series (with the...N. Alemdaroglu, Middle East Technical University, Ankara, Turkey, Prof. L.M.B. da Costa Campos, Instituto Superior Tecnico , Lisboa Codex, Portugal...Defence Research Establishment ITALIE Česká republika Ryvangs Allé 1, P.O. Box 2715 Centro di Documentazione DK-2100 Copenhagen Ø Tecnico
Dutka, Filip; Opalski, Adam S; Garstecki, Piotr
2016-05-24
Many modern analytical assays, for example, droplet digital PCR, or screening of the properties of single cells or single mutated genes require splitting a liquid sample into a number of small (typically ca. nano-liter in volume) independent compartments or droplets. This calls for a method that would allow splitting small (microliter) samples of liquid into libraries of nano-liter droplets without any dead volume or waste. Step emulsification allows for facile protocols that require delivery of only the sample liquid, yet they typically exhibit dependence of the droplet size on the rate at which the sample is injected. Here, we report a novel microfluidic junction that reduces the dependence of the volume of droplets on the rate of injection. We also demonstrate generation of tightly monodisperse nanoliter droplets by introduction of solely the dispersed phase into the system from an automatic pipette. The method presented here can readily be used and can replace the sophisticated devices typically used to generate libraries of nano-liter droplets from liquid samples.
Energy Technology Data Exchange (ETDEWEB)
Bortsaikin, S.M.; Levitan, Yu.S.
1977-07-01
An examination is made of steady-state turbulent flow of a conducting liquid in a cylindrical channel in a longitudinal magnetic field. The system of motion equations and energy can be recorded in a convenient integral form by using the Prandtl hypothesis for computing turbulent coefficients with rather simple assumptions about the nature of the velocity gradient. A small parameter in the equations can be easily identified in direct proximity to the channel's wall that makes it possible to find an approximate analytical solution to this problem in this region. 6 references, 1 figure.
Energy Technology Data Exchange (ETDEWEB)
Okazaki, Motoaki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
1997-11-01
A new numerical method to achieve a rigorous numerical calculation of each phase using a simple explicit method with volume-junction model is proposed. For this purpose, difference equations for numerical use are carefully derived so as to preserve the physical meaning of the basic equations. Specifically, momentum equations for the flow in the volume are newly derived to keep strict conservation of energy within the volume. To prove the validity of the numerical method and of previously proposed basic equations, including the original phase change equations, which were rigorously derived, some numerical calculations were made for each phase independently to examine the correctness of calculated results. The numerical calculation is advanced by simple integration of an explicitly obtained solution of difference equations without any special treatment. Calculated results of density and specific internal energy of each phase for saturated two-phase blowdown behavior are consistent for two different solution scheme as described below. Further, no accumulation of error in mass or energy was found. These results prove the consistency among basic equations, including phase change equations, and the correctness of numerical calculation method. The two different solution schemes used were: (1) solutions of pressure and void fraction in saturated condition were obtained by using mass conservation equation of each phase simultaneously, and (2) fluid properties were calculated directly from mass and energy conservation equation of each phase. (author)
DEFF Research Database (Denmark)
Selmeczi, David; Hansen, Thomas; Met, Özcan
2011-01-01
We present a hybrid chip of polymer and stainless steel designed for high-throughput continuous electroporation of cells in suspension. The chip is constructed with two parallel stainless steel mesh electrodes oriented perpendicular to the liquid flow. The relatively high hydrodynamic resistance ...
DEFF Research Database (Denmark)
Lassen, Tina H; Madsen, Mia; Skovgaard, Lene T
2010-01-01
Smoking is a well-established risk factor for fetal growth restriction and other adverse pregnancy outcomes, and nicotine may be one of the chemical compounds that drive these associations. Nicotine replacement therapy (NRT) is a smoking cessation aid, which can facilitate smoking cessation. It is......, however, unknown whether NRT used during pregnancy impairs fetal growth. The aim of this study was to estimate the association between the use of NRT during pregnancy and offspring birthweight. The study population consisted of 72 761 women enrolled in the Danish National Birth Cohort between 1996......, simultaneous use of more than one NRT product was associated with reduced birthweight (b = -10.73 g per week of NRT use [95% CI -26.51, 5.05]), although the association was not statistically significant. The results of this study suggest that maternal use of NRT in pregnancy does not seriously affect...
DEFF Research Database (Denmark)
Dalgård, Christine; Petersen, Maria Skaalum; Steuerwald, Ulrike;
2016-01-01
BACKGROUND: Insufficient supply of vitamin D during early development may negatively affect offspring growth. METHODS: We examined the association between umbilical cord (UC) serum 25-hydroxyvitamin D (25(OH)D) concentrations and infant size in a study of two Faroese birth cohorts of 1038 singlet...... but not with birthweight and head circumference. Although the paediatric relevance of the observed association is unclear, the possible long-term consequences of late-pregnancy hypovitaminosis D deserve attention....
Fowlie, P. W.; Gould, C. R.; Parry, G J; Phillips, G.; Tarnow-Mordi, W O
1996-01-01
Positive blood cultures in very low birthweight or preterm infants usually reflect bacteraemia, septicaemia, or failure of asepsis during sampling and lead to increased costs and length of stay. Rates of nosocomial, or hospital acquired, bacteraemia may therefore be important indicators of neonatal unit performance, if comparisons are adjusted for differences in initial risk. In a preliminary study the risk of nosocomial bacteraemia was related to initial clinical risk and illness severity me...
DEFF Research Database (Denmark)
Carlsen, E M; Renault, Kristina Martha; Nørgaard, K
2014-01-01
obese and 80 normal weight mothers and their newborn infants and assessed the babies' body composition using dual-energy X-ray absorptiometry. RESULTS: The total and abdominal fat masses of infants born to mother who were obese before pregnancy were 135 g (p ... for gestational age (5.2%) and appropriate for gestational age (9.8%) (p born to obese mothers had higher fat mass at birth, with abdominal fat accumulation. Low birthweight...
Bloomfield, Frank H.; Crowther, Caroline A; Harding, Jane E; Cathryn A. Conlon; Jiang, Yannan; Cormack, Barbara E.
2015-01-01
Background Preterm birth and very small size at birth have long-term effects on neurodevelopment and growth. A relatively small percentage of extremely low birthweight babies suffer from severe neurological disability; however, up to 50 % experience some neurodevelopmental or learning disability in childhood. Current international consensus is that increased protein intake in the neonatal period improves both neurodevelopment and growth, but the quantum of protein required is not known. This ...
Peles, Einat; Sason, Anat; Schreiber, Shaul; Adelson, Miriam
2017-03-01
Methadone maintenance treatment (MMT) is the gold standard for pregnant women with opioid use disorders. Still, low birth-weights were reported, in particular of mothers who became pregnant before admission to MMT. We studied whether an escalating incentive contingency-management approach may contribute to better newborn birth-weights. A nationwide controlled randomized trial among all Israeli methadone/buprenorphine maintenance treatment (MBMT), newly or already in treatment pregnant women was performed. A modified contingency-management protocol with coupons of escalating value depending upon reduction of drug use, cigarette smoking, and alcohol consumption was compared to standard care arm. Drugs in urine, smoking (Fagerstrom score), alcohol use, and depression were monitored. Thirty-five women had 46 pregnancies. In their first pregnancy, 19 from the contingency-management and 16 from the standard care arms were studied. Contingency-management group as compared to the standard care arm included more newly admitted women (36.8% vs. 6.3%, p = .05), with benzodiazepine and cannabis onset at a younger age, and higher proportion of any drug abuse while pregnant (100% vs. 68.8%, p = .01). Fifteen of the contingency-management and 14 of the control arm gave birth (78.9% vs. 87.5%, p = .3) with similar proportions of normal (>2,500 g) birth-weight (71.4% vs. 61.5%, p = .8). Newborns' birth-weight was comparable among the two study arms indicating no contribution of the contingency-management approach. Small sample and baseline differences between arms might have influenced results. Intensive intervention should be evaluated on a larger scale of participants. (Am J Addict 2017;26:167-175). © 2017 American Academy of Addiction Psychiatry.
Institute of Scientific and Technical Information of China (English)
Wang Kexiong; Zhang Laibin; Jiang Hongwei
2007-01-01
Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper,the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.
Directory of Open Access Journals (Sweden)
Shun Zou
2015-02-01
Full Text Available An efficient IBLF-dts scheme is proposed to integrate the bounce-back LBM and FVM scheme to solve the Navier-Stokes equations and the constitutive equation, respectively, for the simulation of viscoelastic fluid flows. In order to improve the efficiency, the bounce-back boundary treatment for LBM is introduced in to improve the grid mapping of LBM and FVM, and the two processes are also decoupled in different time scales according to the relaxation time of polymer and the time scale of solvent Newtonian effect. Critical numerical simulations have been carried out to validate the integrated scheme in various benchmark flows at vanishingly low Reynolds number with open source CFD toolkits. The results show that the numerical solution with IBLF-dts scheme agrees well with the exact solution and the numerical solution with FVM PISO scheme and the efficiency and scalability could be remarkably improved under equivalent configurations.
Scott J Butcher; Pasiorowski, Michal P; Jones, Richard L
2007-01-01
BACKGROUND: The effectiveness of high-frequency chest wall oscillation (HFCWO) in mucolysis and mucous clearance is thought to be dependant on oscillatory flow rate (Fosc). Therefore, increasing Fosc during HFCWO may have a clinical benefit.OBJECTIVES: To examine effects of continuous positive airway pressure (CPAP) on Fosc at two oscillation frequencies in healthy subjects and patients with airway obstruction.METHODS: Five healthy subjects and six patients with airway obstruction underwent 1...
1994-10-10
correction a) Axial velocity contours; L b) Perimetral wall stress Fig 7 Prediction of flow In plane channel rotating in orthogonal mode. Symbols; DNS...layer: anticyclonic in the uipper layer (green line), strong anticyclone in the intermediate layer ( red line), cyclonic in the lower layer (blue). a...mostly to the boundaries, and Red ; 50 so the support wires have little effect on the sphere wake itself. The spheres were towed through a 2.4m 2
von Boetticher, Albrecht; Turowski, Jens M.; McArdell, Brian W.; Rickenmann, Dieter; Kirchner, James W.
2016-08-01
Here, we present a three-dimensional fluid dynamic solver that simulates debris flows as a mixture of two fluids (a Coulomb viscoplastic model of the gravel mixed with a Herschel-Bulkley representation of the fine material suspension) in combination with an additional unmixed phase representing the air and the free surface. We link all rheological parameters to the material composition, i.e., to water content, clay content, and mineral composition, content of sand and gravel, and the gravel's friction angle; the user must specify only two free model parameters. The volume-of-fluid (VoF) approach is used to combine the mixed phase and the air phase into a single cell-averaged Navier-Stokes equation for incompressible flow, based on code adapted from standard solvers of the open-source CFD software OpenFOAM. This effectively single-phase mixture VoF method saves computational costs compared to the more sophisticated drag-force-based multiphase models. Thus, complex three-dimensional flow structures can be simulated while accounting for the pressure- and shear-rate-dependent rheology.
Energy Technology Data Exchange (ETDEWEB)
McHugh, P.R.
1995-10-01
Fully coupled, Newton-Krylov algorithms are investigated for solving strongly coupled, nonlinear systems of partial differential equations arising in the field of computational fluid dynamics. Primitive variable forms of the steady incompressible and compressible Navier-Stokes and energy equations that describe the flow of a laminar Newtonian fluid in two-dimensions are specifically considered. Numerical solutions are obtained by first integrating over discrete finite volumes that compose the computational mesh. The resulting system of nonlinear algebraic equations are linearized using Newton`s method. Preconditioned Krylov subspace based iterative algorithms then solve these linear systems on each Newton iteration. Selected Krylov algorithms include the Arnoldi-based Generalized Minimal RESidual (GMRES) algorithm, and the Lanczos-based Conjugate Gradients Squared (CGS), Bi-CGSTAB, and Transpose-Free Quasi-Minimal Residual (TFQMR) algorithms. Both Incomplete Lower-Upper (ILU) factorization and domain-based additive and multiplicative Schwarz preconditioning strategies are studied. Numerical techniques such as mesh sequencing, adaptive damping, pseudo-transient relaxation, and parameter continuation are used to improve the solution efficiency, while algorithm implementation is simplified using a numerical Jacobian evaluation. The capabilities of standard Newton-Krylov algorithms are demonstrated via solutions to both incompressible and compressible flow problems. Incompressible flow problems include natural convection in an enclosed cavity, and mixed/forced convection past a backward facing step.
Fox, S. R.; Smetana, F. O.
1980-01-01
The contributions to the cruise drag of light aircraft arising from the shape of the engine cowl and the forward fuselage area and also that resulting from the cooling air mass flow through intake and exhaust sites on the nacelle were analyzed. The methods employed for the calculation of the potential flow about an arbitrary three dimensional body are described with modifications to include the effects of boundary layer displacement thickness, a nonuniform onset flow field (such as that due to a rotating propeller), and the presence of air intakes and exhausts. A simple, reliable, largely automated scheme to better define or change the shape of a body is also presented. A technique was developed which can yield physically acceptable skin friction and pressure drag coefficients for isolated light aircraft bodies. For test cases on a blunt nose Cessna 182 fuselage, the technique predicted drag reductions as much as 28.5% by body recontouring and proper placements and sizing of the cooling air intakes and exhausts.
Energy Technology Data Exchange (ETDEWEB)
Herold, S.
1985-03-01
Positron emission tomography in cerebrovascular disease has demonstrated the importance of the relationship between regional cerebral blood flow and the cerebral metabolic activity. In acute stroke it has been found that within the first hours after the onset of symptoms cerebral blood flow in the affected area is more depressed than cerebral oxygen utilisation. This relative preservation of oxygen utilisation results from an increase in the oxygen extraction ratio far above its normal value. However, the oxygen extraction fraction subsequently falls in the following days indicating the transition from a situation of possibly reversible ischaemia to irreversible infarction. In patients with carotid occlusive disease an increase in the oxygen extraction ratio has been observed only in very few cases. It has been shown, however, that at an earlier stage the relationship between CBF and CBV (as CBF/CBV-ratio) provides a sensitive measure of diminished perfusion pressure which could be helpful for the selection of patients for EC-IC bypass surgery. In patients with sickle cell anaemia it has been found that oxygen delivery to the brain is maintained by an increase in cerebral blood flow, whereas the oxygen extraction ratio is not increased despite the presence of a low oxygen affinity haemoglobin. Preliminary observations in classical migraine suggest an ischaemic situation during the attack.
Beljadid, Abdelaziz; Mohammadian, Abdolmajid; Qiblawey, Hazim
2016-10-01
The discretization of the shallow water system on unstructured grids can lead to spurious modes which usually can affect accuracy and/or cause stability problems. This paper introduces a new approach for stability analysis of unstructured linear finite volume schemes for linear shallow water equations with the Coriolis Effect using spectra, pseudospectra, and singular value decomposition. The discrete operator of the scheme is the principal parameter used in the analysis. It is shown that unstructured grids have a large influence on operator normality. In some cases the eigenvectors of the operator can be far from orthogonal, which leads to amplification of solutions and/or stability problems. Large amplifications of the solution can be observed, even for discrete operators which respect the condition of asymptotic stability, and in some cases even for Lax-Richtmyer stable methods. The pseudospectra are shown to be efficient for the verification of stability of finite volume methods for linear shallow water equations. In some cases, the singular value decomposition is employed for further analysis in order to provide more information about the existence of unstable modes. The results of the analysis can be helpful in choosing the type of mesh, the appropriate placements of the variables of the system on the grid, and the suitable discretization method which is stable for a wide range of modes.
Okamura, H
1978-10-01
Two types of spruing methods were used in the casting of the denture type model pattern (thickness, 0.43 mm). Flow of molten metal in the mold was filmed by the improved system of Part 1. When three sprues were attached to the pattern vertically, molten metal passed through each sprue gate flowed being affected by the direction of gravity and revolution of casting machine, and gathered at the lower part of the mold. Next molten metal filled the mold from the lower part to the upper part. In this spruing type, molten metal turned its direction of flow several times. At the middle stage of casting, the inflow volume per unit time (inflow rate), v (mm3/10-2)s)was evaluated as v = 12.36 + 5.16A-0.16 A2 (A: total cross-sectional areas of sprues). The inflow rate increased with increase of the area of the sprues, but it saturated. When the main sprue and the subsprues were attached at the posterior border, the molten metal filled the mold from the lower part to the upper part quietly. In this spruing type, the casting mold was set facing its sprue gates downwards. The inflow rate at the middle stage of casting was evaluated as v = 21.05 + 1.79 C (C: the cross-sectional area of the main sprue). The inflow rate increased linearly with increase of the area of the main sprue.
DEFF Research Database (Denmark)
Selmeczi, Dávid; Hansen, Thomas Steen; Met, Özcan
2011-01-01
of the micrometer sized holes in the meshes compared to the main channel enforces an almost homogeneous flow velocity between the meshes. Thereby, very uniform electroporation of the cells can be accomplished. Successful electroporation of 20 million human dendritic cells with mRNA is demonstrated. The performance...... of the chip is similar to that of the traditional electroporation cuvette, but without an upper limit on the number of cells to be electroporated. The device is constructed with two female Luer parts and can easily be integrated with other microfluidic components. Furthermore it is fabricated from injection...
2001-01-01
This document presents the full-scale analyses of the CFD RSRM. The RSRM model was developed with a 20 second burn time. The following are presented as part of the full-scale analyses: (1) RSRM embedded inclusion analysis; (2) RSRM igniter nozzle design analysis; (3) Nozzle Joint 4 erosion anomaly; (4) RSRM full motor port slag accumulation analysis; (5) RSRM motor analysis of two-phase flow in the aft segment/submerged nozzle region; (6) Completion of 3-D Analysis of the hot air nozzle manifold; (7) Bates Motor distributed combustion test case; and (8) Three Dimensional Polysulfide Bump Analysis.
Early cessation of breast milk feeding in very low birthweight infants.
Killersreiter, B; Grimmer, I; Bührer, C; Dudenhausen, J W; Obladen, M
2001-01-01
This investigation was carried out to comparatively assess the duration of breast milk feeding and to analyze risk factors for early cessation of breast milk feeding in term and very preterm infants. A cohort study was performed in 89 consecutive very low birthweight (VLBW) infants (2500 g born in the same hospital matched for gender and multiplicity. Median duration of breast milk feeding, as determined from charts and questionnaires mailed to the mothers at 6 and 12 months corrected age, was 36 days in VLBW infants, compared to 112 days in control infants (P35 years and spontaneous pregnancy (as opposed to pregnancy following infertility treatment) in term infants. Multivariate analysis revealed that VLBW, smoking and low parental school education were independent negative predictors of breast milk feeding. While these results emphasize the need for special support of VLBW infant mothers promoting lactation, the relationships between smoking, school education and breast milk feeding in both strata show that efforts to increase breast milk feeding require a public health perspective.
Survival of a very low-birthweight infant with Potter sequence on long-term hemodialysis.
Miyahara, Jun; Yamamoto, Masaki; Motoshige, Kyoko; Fujita, Naoya; Ohki, Shigeru
2016-07-01
Recent advances in neonatal cardiorespiratory management and neonatal renal replacement therapy have led to occasional reports of favorable short-term and long-term outcomes for Potter sequence, once thought to be fatal. The present patient was a girl born at a gestational age of 34 weeks 4 days with a birthweight of 1398 g. She was diagnosed with Potter sequence complicated by pulmonary hypoplasia due to left renal agenesis and small right kidney. Hemodialysis was started because anuria persisted even after persistent pulmonary hypertension receded and cardiorespiratory status improved. Peritoneal dialysis during the clinical course failed to achieve stability because of pericatheter leakage and frequent obstruction of the peritoneal dialysis catheter; in the meantime, hemodialysis was also performed. Once bodyweight passed 3.5 kg, peritoneal dialysis became more feasible with stability; the patient was discharged at 9 months and at the time of writing was on peritoneal dialysis at home, and renal transplantation was planned.
Grunewaldt, Kristine Hermansen; Skranes, Jon; Brubakk, Ann-Mari; Lähaugen, Gro C C
2016-02-01
Working memory deficits are frequently found in children born preterm and have been linked to learning disabilities, and cognitive and behavioural problems. Our aim was to evaluate if a computerized working memory training program has long-term positive effects on memory, learning, and behaviour in very-low-birthweight (VLBW) children at age 5 to 6 years. This prospective, intervention study included 20 VLBW preschool children in the intervention group and 17 age-matched, non-training VLBW children in the comparison group. The intervention group trained with the Cogmed JM working memory training program daily for 5 weeks (25 training sessions). Extensive neuropsychological assessment and parental questionnaires were performed 4 weeks after intervention and at follow-up 7 months later. For most of the statistical analyses, general linear models were applied. At follow-up, higher scores and increased or equal performance gain were found in the intervention group than the comparison group on memory for faces (p=0.012), narrative memory (p=0.002), and spatial span (p=0.003). No group differences in performance gain were found for attention and behaviour. Computerized working memory training seems to have positive and persisting effects on working memory, and visual and verbal learning, at 7-month follow-up in VLBW preschool children. We speculate that such training is beneficial by improving the ability to learn from the teaching at school and for further cognitive development. © 2015 Mac Keith Press.
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Magnani Cinzia
2009-06-01
Full Text Available Abstract Background Hypospadias is a congenital displacement of the urethral meatus in male newborns, being either an isolated defect at birth or a sign of sexual development disorders. The aim of this study was to assess the prevalence rate of hypospadias in different Districts of Italy, in order to make a comparison with other countries all over the world. Methods We reviewed all the newborns file records (years 2001–2004 in 15 Italian Hospitals. Results We found an overall hypospadias prevalence rate of 3.066 ± 0.99 per 1000 live births (82.48% mild hypospadias, 17.52% moderate-severe. In newborns Small for Gestational Age (birthweight th percentile of any gestational age the prevalence rate of hypospadias was 6.25 per 1000 live births. Performing multivariate logistic regression analysis for different degrees of hypospadias according to severity, being born SGA remained the only risk factor for moderate-severe hypospadias (p = 0.00898 but not for mild forms (p > 0.1. Conclusion In our sample the prevalence of hypospadias results as high as reported in previous European and American studies (3–4 per 1000 live births. Pathogenesis of isolated hypospadias is multifactorial (genetic, endocrine and environmental factors: however, the prevalence rate of hypospadias is higher in infants born small for gestational age than in newborns with normal birth weight.
Dembinski, J; Arpe, V; Kroll, M; Hieronimi, G; Bartmann, P
2000-01-01
BACKGROUND—Thyroid function disorders have often been observed in preterm infants after intravenous administration of iodinated contrast medium. The effect on thyroid function depends on the dosage, but the choice of the contrast medium may be equally important, as there are appreciable pharmacological differences between them. METHOD—Thyroid function was analysed in 20 very low birthweight infants of gestational age less than 30 weeks after injection of iopromide, a monomeric non-ionic iodinated contrast medium. Levels of free thyroxine and thyroid stimulating hormone were compared with those in 26 control infants. RESULTS—Free thyroxine levels in all study infants ranged from 9.0 to 25.7 pmol/l (days 14-21) and 9.0 to 23.2 pmol/l (days 35-49), and thyroid stimulating hormone levels ranged from 0.13 to 0.26mU/l (days 14-21) and 0.26 to 11.11 mU/l (days 35-49). These levels were not altered after injection of iopromide. CONCLUSION—The risk of transient hypothyroidism or hyperthyrotropinaemia may be reduced with the use of iopromide compared with other contrast media. PMID:10794789
Outcomes of very-low-birthweight infants after discharge with a discharge weight of 1500 grams.
Ahmadpour-Kacho, Mousa; Pasha, Yadollah Zahed; Aliabadi, Behdis Motevalli
2012-04-01
Discharge of very-low-birthweight (VLBW) neonates from hospital is an important issue and has a standard criterion worldwide. According to this criterion, VLBW infants will be discharged from hospital when weighing 1800-2100 g but in the newborn services at Amirkola Children's Hospital (ACH), VLBW neonates are discharged when reaching 1500 g. The aim of this study was to determine the safety of this policy. In this analytic-prospective study, 100 premature neonates with discharging weight (DW) of 1500 g and a control group of 150 neonates with DW of 1600-2500 g were included. Both groups showed similar socioeconomic, perinatal and postnatal conditions. They were admitted and treated in the newborn services at ACH. The outcome variables, including death after discharge, readmission and need for emergency visit for an acute problem up to 3 months after discharge, were studied. The information was analyzed by SPSS-16 software and a P-value discharge reached a significant difference between the two groups (31 in the case group vs 21 in the control group, P= 0.000), but there were no significant differences in the readmission rate and death after discharge (two deaths and 15 readmissions in the case group vs two deaths and 21 readmissions in the control group, P= 0.855) In order to decrease the need for emergency visits, we suggest a program of early hospital discharge with home nursing visits and neonatologist support. © 2011 The Authors. Pediatrics International © 2011 Japan Pediatric Society.
Jones, R L; Cederberg, H M S; Wheeler, S J; Poston, L; Hutchinson, C J; Seed, P T; Oliver, R L; Baker, P N
2010-01-01
Teenagers are susceptible to delivering small-for-gestational-age (SGA) infants. Previous studies suggest that maternal growth may contribute, as a result of preferential nutrient partitioning to the mother. We investigated the impact of maternal growth on birthweight in pregnant teenagers in the UK, and examined endocrine mediators of nutrient partitioning. A prospective observational multicentre study, About Teenage Eating, conducted between 2004 and 2007. Four hospitals in socially-deprived areas of Manchester and London. A total of 500 pregnant adolescents (14-18 years of age) with a singleton pregnancy were recruited at 10-21 weeks of gestation, with follow-up studies on 368 subjects. A cohort of 80 pregnant adults (25-40 years of age) provided a control group for determining growth. Skeletal growth, weight gain and skinfold thickness were measured from first to third trimester, together with maternal levels of micronutrients and metabolic hormones: insulin-like growth factor (IGF) system and leptin. Dietary analyses were performed. SGA birth. Maternal growth was not associated with SGA birth: growing mothers delivered more large-for-gestational-age infants (OR 2.51; P Teenagers that were underweight at booking or with low weight gain were at greater risk of SGA birth. Maternal growth was not detrimental to fetal growth in this UK population of teenagers. Greater weight gain and higher concentrations of IGF-I in growing teenagers may provide anabolic drive for maternal and fetal growth.
Sharma, Prabhakar; Poulsen, Tjalfe G
2010-07-01
Gas-phase dispersion in granular biofilter materials with a wide range of particle sizes was investigated using atmospheric air and nitrogen as tracer gases. Two types of materials were used: (1) light extended clay aggregates (LECA), consisting of highly porous particles, and (2) gravel, consisting of solid particles. LECA is a commercial material that is used for insulation, as a soil conditioner, and as a carrier material in biofilters for air cleaning. These two materials were selected to have approximately the same particle shape. Column gas transport experiments were conducted for both materials using different mean particle diameters, different particle size ranges, and different gas flow velocities. Measured breakthrough curves were modeled using the advection-dispersion equation modified for mass transfer between mobile and immobile gas phases. The results showed that gas dispersivity increased with increasing mean particle diameter for LECA but was independent of mean particle diameter for gravel. Gas dispersivity also increased with increasing particle size range for both media. Dispersivities in LECA were generally higher than for gravel. The mobile gas content in both materials increased with increasing gas flow velocity but it did not show any strong dependency on mean particle diameter or particle size range. The relative fraction of mobile gas compared with total porosity was highest for gravel and lowest for LECA likely because of its high internal porosity.
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W John Watkins
2016-05-01
Full Text Available Low birthweight (LBW is associated with increased mortality in infancy, but its association with mortality in later childhood and adolescence is less clear. We investigated the association between birthweight and all-cause mortality and identified major causes of mortality for different birthweight groups.We conducted a population study of all live births occurring in England and Wales between 1 January 1993 and 31 December 2011. Following exclusions, the 12,355,251 live births were classified by birthweight: 500-1,499 g (very LBW [VLBW], n = 139,608, 1,500-2,499 g (LBW, n = 759,283, 2,500-3,499 g (n = 6,511,411, and ≥3,500 g (n = 4,944,949. The association of birthweight group with mortality in infancy (<1 y of age and childhood/adolescence (1-18 y of age was quantified, with and without covariates, through hazard ratios using Cox regression. International Classification of Diseases codes identified causes of death. In all, 74,890 (0.61% individuals died between birth and 18 y of age, with 23% of deaths occurring after infancy. Adjusted hazard ratios for infant deaths were 145 (95% CI 141, 149 and 9.8 (95% CI 9.5, 10.1 for the VLBW and LBW groups, respectively, compared to the ≥3,500 g group. The respective hazard ratios for death occurring at age 1-18 y were 6.6 (95% CI 6.1, 7.1 and 2.9 (95% CI 2.8, 3.1. Male gender, the youngest and oldest maternal age bands, multiple births, and deprivation (Index of Multiple Deprivation score also contributed to increased deaths in the VLBW and LBW groups in both age ranges. In infancy, perinatal factors, particularly respiratory issues and infections, explained 84% and 31% of deaths in the VLBW and LBW groups, respectively; congenital malformations explained 36% and 23% in the LBW group and ≥2,500 g groups (2,500-3,499 g and ≥3,500 g groups combined, respectively. Central nervous system conditions explained 20% of deaths in childhood/adolescence in the VLBW group, with deaths from neoplasms and
Rowbottom, Lynn; Workman, Clive; Roberts, Norman B
2009-09-01
Selected-ion flow-tube mass spectrometry (SIFT-MS) is particularly suited for the analysis of volatile low molecular weight compounds. We have evaluated this technique for the assay of different alcohols in aqueous solutions, including blood plasma, and in particular whether the osmolality or sample volume affected vapourisation. Solutions of three different alcohols (methanol, ethanol and isopropanol) ranging from 0.005 to 50 mmol/L were prepared in deionised water (0 milliosmol), phosphate-buffered saline (690 mOsm), isotonic saline (294 mOsm) and plasma (296 mOsm). The vapour above the sample (50 to 1000 microL) contained in air-tight tubes at 37 degrees C was aspirated into the instrument. The outputs for ethanol, methanol and isopropanol were linear over the concentration range and independent of the sample volume and relatively independent of the osmolar concentration. SIFT-MS can reliably and accurately measure common alcohols in the headspace above aqueous solutions, including serum/plasma. This novel application of SIFT-MS is easy to follow, requires no sample preparation and the wide dynamic range will facilitate measurement of alcohols present from normal metabolism as well as when taken in excess or in accidental poisoning.
Mirjalili, Shahab; Ivey, Christopher Blake; Mani, Ali
2016-11-01
The diffuse interface(DI) and volume of fluid(VOF) methods are mass conserving front capturing schemes which can handle large interfacial topology changes in realistic two phase flows. The DI method is a conservative phase field method that tracks an interface with finite thickness spread over a few cells and does not require reinitialization. In addition to having the desirable properties of level set methods for naturally capturing curvature and surface tension forces, the model conserves mass continuously and discretely. The VOF method, which tracks the fractional tagged volume in a cell, is discretely conservative by requiring costly geometric reconstructions of the interface and the fluxes. Both methods however, suffer from inaccuracies in calculation of curvature and surface tension forces. We present a quantitative comparison of these methods in terms of their accuracy, convergence rate, memory, and computational cost using canonical 2D two-phase test cases: damped surface wave, oscillating drop, equilibrium static drop, and dense moving drop. We further compared the models in their ability to handle thin films by looking at the impact of a water drop onto a deep water pool. Considering these results, we suggest qualitative guidelines for using the DI and VOF methods. Supported by ONR.
钒电池电解液体积变化规律研究%Electrolyte Volume Change Study in All Vanadium Redox Flow Battery
Institute of Scientific and Technical Information of China (English)
赵永涛; 席靖宇; 滕祥国; 武增华; 邱新平
2011-01-01
Rule of electrolyte volume change was studied when the all vanadium redox flow battery was running stably with a cation exchange membrane. Electric transfer of ions will make the volume change linearly with the changing of charge-discharge capacity, that is, the positive electrolyte will be less and the negative electrolyte will be more during the charge process, which will be reversed in the discharge process.The direction of net infiltration of vanadium ions is from the negtive electrolyte to the positive electrolyte,which will make the volume of positive electrolyte larger in a couple of cycles. The direction of net water transfer is the same as the vanadium ions.%研究了钒电池在使用阳离子交换膜稳定运行过程中电解液体积的变化情况,分析了影响因素,并总结了变化规律.离子的电迁移使电解液体积随充放电容量的变化线性改变,充电过程正极电解液体积线性减小,负极电解液体积线性增大;放电过程反之.多次充放电循环过程中,钒离子的净渗透方向是由负极到正极,水的净变化方向与钒离子相同,最终使得多次循环过程正极电解液的体积逐渐增加.
Dumanli, Rukiye; Attar, Azade; Erci, Vildan; Isildak, Ibrahim
2016-04-01
A microliter dead-volume flow-through cell as a potentiometric detector is described in this article for sensitive, selective and simultaneous detection of common monovalent anions and cations in single column ion chromatography for the first time. The detection cell consisted of less selective anion- and cation-selective composite membrane electrodes together with a solid-state composite matrix reference electrode. The simultaneous separation and sensitive detection of sodium (Na(+)), potassium (K(+)), ammonium (NH4 (+)), chloride (Cl(-)) and nitrate (NO3 (-)) in a single run was achieved by using 98% 1.5 mM MgSO4 and 2% acetonitrile eluent with a mixed-bed ion-exchange separation column without suppressor column system. The separation and simultaneous detection of the anions and cations were completed in 6 min at the eluent flow-rate of 0.8 mL/min. Detection limits, at S/N = 3, were ranged from 0.2 to 1.0 µM for the anions and 0.3 to 3.0 µM for the cations, respectively. The developed method was successfully applied to the simultaneous determination of monovalent anions and cations in several environmental and biological samples.
Effect of dynamic contact angle in a volume of fluid (VOF) model for a microfluidic capillary flow.
Ashish Saha, Auro; Mitra, Sushanta K
2009-11-15
We perform three-dimensional numerical and experimental study of the dynamic contact angle using volume of fluid (VOF) method applied to microfluidic channels with integrated pillars. Initially, we evaluated different dynamic contact angle models (hydrodynamic, molecular kinetic and empirical) for capillary filling of a two-dimensional microchannel using analytical formulation. Further, the models which require a minimum prescription of adjustable parameters are only used for the study of capillary filling of microchannels with integrated pillars using different working fluids such as DI water, ethanol and isopropyl alcohol. Different microchannel geometry with varying diameter/height/spacing were studied for circular pillars. Effect of square pillars and changing the overall number of pillars on the capillary phenomena were also simulated. Our study demonstrated that the dynamic contact angle models modifies the transient response of the meniscus displacement and also the observed trends are model specific for the various microchannel geometries and working fluids. However, the different models have minimal effect on the meniscus profile. Different inlet boundary conditions were applied to observe the effect of grid resolution selected for numerical study on the capillary filling time. A grid dependent dynamic contact angle model which incorporates effective slip in the model was also used to observe the grid convergence of the numerical results. The grid independence was shown to improve marginally by applying the grid dependent dynamic contact angle model. Further we did numerical experiments of capillary filling considering variable surface wettability on the top and bottom walls of the microchannel with alternate hydrophilic-hydrophobic patterns. The meniscus front pinning was noticed for a high wetting contrast between the patterns. Non uniform streamline patterns indicated mixing of the fluid when using patterned walls. Such a microfluidic device with
Dürig, Tobias; Gudmundsson, Magnús; Högnadóttir, Thordís; Jónsdóttir, Ingibjörg; Gudbjörnsson, Snaebjörn; Lárusson, Örnólfur; Höskuldsson, Ármann; Thordarson, Thorvaldur; Riishuus, Morten; Magnússon, Eyjólfur
2015-04-01
Monitoring of lava-producing eruptions involves systematic measurement of flow field volumes, which in turn can be used to obtain average magma discharge over the period of observation. However, given inaccessibility to the interior parts of active lava fields, remote sensing techniques must be applied. Several satellite platforms provide data that can be geo-referenced, allowing area estimation. However, unless sterographic or tandem satellite data are available, the determination of thicknesses is non-trivial. The ongoing eruption ('Nornaeldar')at Dyngjusandurin the Icelandic highlands offers an opportunity to monitor the temporal and spatial evolution of a typical Icelandic lava flow field. The mode of emplacementis complex and includesboth horizontal and vertical stacking, inflation of lobes and topographic inversions. Due to the large extent of the flow field (>83 km2 on 5 Jan 2015, and still growing) and its considerable local variation in thickness (30 m) and surface roughness, obtaining robust quantification of lava thicknesses is very challenging,despite the lava is being emplaced onto a low-relief sandur plain. Creative methods have been implemented to obtain as reliable observation as possible into the third dimension: Next to areal extent measurements from satellites and maps generated with airborne synthetic-aperture radar (SAR), lava thickness profiles are regularly obtained by low-level flights with a fixed-wing aircraft that is equipped with a ground clearance radar coupled witha submeter DGPS,a system originally designed for monitoring surface changes of glaciers above geothermally active areas.The resulting radar profile data are supplemented by analyses of aerial photos and complemented by results from an array of ground based thickness measurement methods. The initial results indicate that average effusion ratewas ~200 m3/s in the first weeks of the eruption (end August, early September) but declined to 50-100 m3/s in November to December period
Panday, Sorab; Langevin, Christian D.; Niswonger, Richard G.; Ibaraki, Motomu; Hughes, Joseph D.
2013-01-01
A new version of MODFLOW, called MODFLOW–USG (for UnStructured Grid), was developed to support a wide variety of structured and unstructured grid types, including nested grids and grids based on prismatic triangles, rectangles, hexagons, and other cell shapes. Flexibility in grid design can be used to focus resolution along rivers and around wells, for example, or to subdiscretize individual layers to better represent hydrostratigraphic units. MODFLOW–USG is based on an underlying control volume finite difference (CVFD) formulation in which a cell can be connected to an arbitrary number of adjacent cells. To improve accuracy of the CVFD formulation for irregular grid-cell geometries or nested grids, a generalized Ghost Node Correction (GNC) Package was developed, which uses interpolated heads in the flow calculation between adjacent connected cells. MODFLOW–USG includes a Groundwater Flow (GWF) Process, based on the GWF Process in MODFLOW–2005, as well as a new Connected Linear Network (CLN) Process to simulate the effects of multi-node wells, karst conduits, and tile drains, for example. The CLN Process is tightly coupled with the GWF Process in that the equations from both processes are formulated into one matrix equation and solved simultaneously. This robustness results from using an unstructured grid with unstructured matrix storage and solution schemes. MODFLOW–USG also contains an optional Newton-Raphson formulation, based on the formulation in MODFLOW–NWT, for improving solution convergence and avoiding problems with the drying and rewetting of cells. Because the existing MODFLOW solvers were developed for structured and symmetric matrices, they were replaced with a new Sparse Matrix Solver (SMS) Package developed specifically for MODFLOW–USG. The SMS Package provides several methods for resolving nonlinearities and multiple symmetric and asymmetric linear solution schemes to solve the matrix arising from the flow equations and the Newton
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Wei Chen
2010-01-01
Full Text Available This study examines the genetic influence of β-adrenergic receptor gene polymorphisms (β2-AR Arg16Gly and β3-AR Trp64Arg on the relationship of birthweight to longitudinal changes of blood pressure (BP from childhood to adulthood in 224 black and 515 white adults, aged 21–47 years, enrolled in the Bogalusa Heart Study. Blacks showed significantly lower birthweight and frequencies of β2-AR Gly16 and β3-AR Trp64 alleles and higher BP levels and age-related trends than whites. In multivariable regression analyses using race-adjusted BP and birthweight, low birthweight was associated with greater increase in age-related trend of systolic BP (standardized regression coefficient β=−0.09, P=.002 and diastolic BP (β=−0.07, P=.037 in the combined sample of blacks and whites, adjusting for the first BP measurement in childhood, sex, age, and gestational age. Adjustment for the current body mass index strengthened the birthweight-BP association. Importantly, the strength of the association, measured as regression coefficients, was modulated by the combination of β2-AR and β3-AR genotypes for systolic (P=.042 for interaction and diastolic BP age-related trend (P=.039 for interaction, with blacks and whites showing a similar trend in the interaction. These findings indicate that the intrauterine programming of BP regulation later in life depends on β-AR genotypes.
Cas, Ray A.F.; Wright, Heather M.; Folkes, Christopher B.; Lesti, Chiara; Porreca, Massimiliano; Giordano, Guido; Viramonte, Jose G.
2011-01-01
The 2.08-Ma Cerro Galán Ignimbrite (CGI) represents a >630-km3 dense rock equivalent (VEI 8) eruption from the long-lived Cerro Galán magma system (∼6 Ma). It is a crystal-rich (35–60%), pumice (multiple depositional units, often separated by pyroclastic surge deposits. The CGI preserves a widespread sub-horizontal fabric, defined by aligned elongate pumice and lithic clasts, and minerals (e.g. biotite). A sub-horizontal anisotropy of magnetic susceptibility fabric is defined by minute magnetic minerals in all localities where it has been analysed. The CGI is poor in both vent-derived (‘accessory’) lithics and locally derived lithics from the ground surface (‘accidental’) lithics. Locally derived lithics are small (order to explain the contemporaneous maintenance of high particle concentration, high sedimentation rate at the depositional boundary layer and a high level of mobility, it is also proposed that the flow(s) was continuously supplied at a high mass feeding rate. It is also proposed that internal gas pressure within the flow, directed downwards onto the substrate over which the flow was passing, reduced the friction between the flow and the substrate and also enhanced its mobility. The pervasive sub-horizontal fabric of aligned pumice, lithic and even biotite crystals indicates a consistent horizontal shear force existed during transport and deposition in the basal granular flow, consistent with the existence of a laminar, shearing, granular flow regime during the final stages of transport and deposition.
Prognostic factors for low birthweight repetition in successive pregnancies: a cohort study
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Sclowitz Iândora Krolow Timm
2013-01-01
Full Text Available Abstract Background To identify prognostic factors associated with recurrence of low birthweight (LBW in successive gestations, a study was carried out with a subsample of mothers enrolled in the 2004 Pelotas Birth Cohort. Methods Data were collected by hospital-based interviews. Newborns were weighed and measured. Gestational age was defined according to the date of last menstrual period, ultra-sound scan before the 20th week of pregnancy or the Dubowitz method. Mothers who reported at least one LBW newborn in the two previous gestations were included. Prevalence ratios (PR and 95% confidence intervals were estimated from Poisson Regression. All estimates were adjusted for parity. Results A total of 4558 births were identified in 2004, and 565 met inclusion criteria, out of which 86 (15.2% repeated LBW in 2004. Among mothers with two LBW babies before 2004, 47.9% presented LBW recurrence. Belonging to the highest socio-economic stratum (PR 0.89; 0.01-0.46 and gaining ≥ 10 kg during pregnancy (PR 0.09; 0.01-0.77 were protective against LBW recurrence. Higher risk of LBW recurrence was observed among mothers with higher parity (≥3 previous deliveries; PR=1.93; 95% CI 1.23-3.02; who had given birth to a previous preterm baby (PR=4.01; 2.27-7.10; who delivered a female newborn in current gestation (PR=2.61; 1.45-4.69; and that had not received adequate antenatal care (PR=2.57; 1-37-4.81. Conclusion Improved quality of antenatal care and adequate maternal weight gain during pregnancy may be feasible strategies to prevent LBW repetition in successive pregnancies.
Permissive hypotension in the extremely low birthweight infant with signs of good perfusion.
LENUS (Irish Health Repository)
Dempsey, E M
2012-01-31
INTRODUCTION: Many practitioners routinely treat infants whose mean arterial blood pressure in mm Hg is less than their gestational age in weeks (GA). OBJECTIVE: To assess the effectiveness of utilising a combined approach of clinical signs, metabolic acidosis and absolute blood pressure (BP) values when deciding to treat hypotension in the extremely low birthweight (ELBW) infant. METHODS: Retrospective cohort study of all live born ELBW infants admitted to our neonatal intensive care unit over a 4-year period. Patients were grouped as either normotensive (BP never less than GA), hypotensive and not treated (BP
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Amitha R Aroor
2012-02-01
Full Text Available Objectives: The aim of this study was to compare the biochemical parameters, weight gain, osteopenia and phosphate supplementation in very low birth weight (VLBW neonates receiving early versus late parenteral nutrition (EPN versus LPN. Methods: A retrospective study was undertaken in the level III Neonatal Intensive Care Unit at Sultan Qaboos University Hospital, Oman: from January 2007 to October 2008 (LPN group, n = 47 and from January 2009 to June 2010 (EPN group, n = 44. Demographic data, anthropometric and laboratory parameters were extracted from the electronic record system. Results: The mean age of PN initiation was LPN = 47.3 hours versus EPN = 14.3 hours. Biochemical parameters analysed during the first week of life revealed a reduction in hypernatraemia (12.7% versus 6.8% and non-oliguric hyperkalemia (12.7% versus 6.8% in EPN, with no significant differences in acidosis and urea levels between the two groups. Hyperglycemia >12 mmol/L in <1000g was higher in EPN. Nutritional parameters in 81 babies who survived/stayed in the unit up to a corrected gestational age (CGA of 34 weeks (40 in LPN and 41 in EPN, revealed a reduction in metabolic bone disease (osteopenia of prematurity [OOP], 17.5% versus 7.3% and the need for phosphate supplementation (22.5% versus 7.3% in the EPN group. There was no increase in acidosis or cholestasis. No difference was noted in albumin levels, time to full feeds, time to regain birthweight and mean weight gain per day till 34 weeks corrected CGA. Conclusion: EPN in VLBW newborns is well tolerated and reduces hypernatraemia, non-oliguric hyperkalemia, OOP and the need for phosphate supplementation.
Stirrat, Laura I; O'Reilly, James R; Barr, Sarah M; Andrew, Ruth; Riley, Simon C; Howie, Alexander F; Bowman, Maria; Smith, Roger; Lewis, John G; Denison, Fiona C; Forbes, Shareen; Seckl, Jonathan R; Walker, Brian R; Norman, Jane E; Reynolds, Rebecca M
2016-01-01
The maternal hypothalamic-pituitary-adrenal-axis (HPAA) undergoes dramatic activation during pregnancy. Increased cortisol and corticotrophin-releasing-hormone (CRH) associate with low birthweight and preterm labor. In non-pregnant obesity, the HPAA is activated but circulating cortisol levels are normal or lower than in lean women. We hypothesized that maternal cortisol levels would be lower in obese pregnancy, and would associate with increased fetal size and length of gestation. Fasting serum cortisol was measured at 16, 28 and 36 weeks gestation and at 3-6 months postpartum in 276 severely obese and 135 lean women. In a subset of obese (n=20) and lean (n=20) we measured CRH, hormones that regulate bioavailable cortisol (corticosteroid-binding-globulin, estradiol, estriol, and progesterone). Urinary glucocorticoid metabolites were measured in pregnant (obese n=6, lean n=5) and non-pregnant (obese n=7, lean n=7) subjects. Maternal cortisol and HPAA hormones were lower in obese pregnancy. Total urinary glucocorticoid metabolites increased significantly in lean pregnancy, but not in obese. Lower maternal cortisol in obese tended to be associated with increased birthweight (r=-0.13, p=0.066). In obese, CRH at 28 weeks correlated inversely with gestational length (r=-0.49, p=0.04), and independently predicted gestational length after adjustment for confounding factors (mean decrease in CRH of -0.25 pmol/L (95% CI -0.45 to -0.043 pmol/L) per/day increase in gestation). In obese pregnancy, lower maternal cortisol without an increase in urinary glucocorticoid clearance may indicate a lesser activation of the HPAA than in lean pregnancy. This may offer a novel mechanism underlying increased birthweight and longer gestation in obese pregnancy. Copyright © 2015 Elsevier Ltd. All rights reserved.
LENUS (Irish Health Repository)
Khashan, Ali S
2010-01-01
BACKGROUND: Higher risks of preterm birth and small for gestational age babies have been reported in teenagers. The aim of this study was to investigate the relationship between first and second teenage pregnancies and preterm birth, birthweight and small for gestational age (SGA). METHODS: All women aged 14 to 29 yrs who gave birth to live singletons in the North Western Region of England between January 1st 2004 and December 31st 2006 were identified. Women were classified in three groups; 14-17 yrs, 18-19 yrs and 20-29 yrs (reference group). The outcome measures were preterm birth, very preterm birth, birthweight, SGA (< 5th percentile), very SGA (VSGA< 3rd percentile). We compared these outcome measures in teenagers\\' first and second pregnancies with those of mothers aged 20 to 29 yrs. RESULTS: The risk of preterm birth was increased in first (OR = 1.21, [95% CI: 1.01-1.45]) and second (OR = 1.93, [95% CI: 1.38-2.69]) time mothers aged 14-17 yrs compared to the reference group. Birthweight was reduced in the first (mean difference = -24 g; [95% CI: -40, -7]) and second (mean difference = -80 g; [95% CI: -115, -46]) time mothers aged 14-17 yrs compared to the reference group. There was some evidence of a protective effect against VSGA in 14-17 yr old first time mothers (OR = 0.79, [95% CI: 0.63-0.99]). CONCLUSIONS: Teenage mothers are at increased risk of preterm birth compared to adult mothers and this risk is further increased in second time teen pregnancies. This study highlights the importance of ensuring pregnant teenagers have appropriate antenatal care. A first pregnancy may be the first and only time a pregnant teenager interacts with health services and this opportunity for health education and the promotion of contraception should not be overlooked.
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Baker Philip N
2010-07-01
Full Text Available Abstract Background Higher risks of preterm birth and small for gestational age babies have been reported in teenagers. The aim of this study was to investigate the relationship between first and second teenage pregnancies and preterm birth, birthweight and small for gestational age (SGA. Methods All women aged 14 to 29 yrs who gave birth to live singletons in the North Western Region of England between January 1st 2004 and December 31st 2006 were identified. Women were classified in three groups; 14-17 yrs, 18-19 yrs and 20-29 yrs (reference group. The outcome measures were preterm birth, very preterm birth, birthweight, SGA (th percentile, very SGA (VSGArd percentile. We compared these outcome measures in teenagers' first and second pregnancies with those of mothers aged 20 to 29 yrs. Results The risk of preterm birth was increased in first (OR = 1.21, [95% CI: 1.01-1.45] and second (OR = 1.93, [95% CI: 1.38-2.69] time mothers aged 14-17 yrs compared to the reference group. Birthweight was reduced in the first (mean difference = -24 g; [95% CI: -40, -7] and second (mean difference = -80 g; [95% CI: -115, -46] time mothers aged 14-17 yrs compared to the reference group. There was some evidence of a protective effect against VSGA in 14-17 yr old first time mothers (OR = 0.79, [95% CI: 0.63-0.99]. Conclusions Teenage mothers are at increased risk of preterm birth compared to adult mothers and this risk is further increased in second time teen pregnancies. This study highlights the importance of ensuring pregnant teenagers have appropriate antenatal care. A first pregnancy may be the first and only time a pregnant teenager interacts with health services and this opportunity for health education and the promotion of contraception should not be overlooked.
Khashan, Ali S; Baker, Philip N; Kenny, Louise C
2010-07-09
Higher risks of preterm birth and small for gestational age babies have been reported in teenagers. The aim of this study was to investigate the relationship between first and second teenage pregnancies and preterm birth, birthweight and small for gestational age (SGA). All women aged 14 to 29 yrs who gave birth to live singletons in the North Western Region of England between January 1st 2004 and December 31st 2006 were identified. Women were classified in three groups; 14-17 yrs, 18-19 yrs and 20-29 yrs (reference group). The outcome measures were preterm birth, very preterm birth, birthweight, SGA (teenagers' first and second pregnancies with those of mothers aged 20 to 29 yrs. The risk of preterm birth was increased in first (OR = 1.21, [95% CI: 1.01-1.45]) and second (OR = 1.93, [95% CI: 1.38-2.69]) time mothers aged 14-17 yrs compared to the reference group. Birthweight was reduced in the first (mean difference = -24 g; [95% CI: -40, -7]) and second (mean difference = -80 g; [95% CI: -115, -46]) time mothers aged 14-17 yrs compared to the reference group. There was some evidence of a protective effect against VSGA in 14-17 yr old first time mothers (OR = 0.79, [95% CI: 0.63-0.99]). Teenage mothers are at increased risk of preterm birth compared to adult mothers and this risk is further increased in second time teen pregnancies. This study highlights the importance of ensuring pregnant teenagers have appropriate antenatal care. A first pregnancy may be the first and only time a pregnant teenager interacts with health services and this opportunity for health education and the promotion of contraception should not be overlooked.
DEFF Research Database (Denmark)
Platt, Mary Jane; Cans, Christine; Johnson, Ann
2007-01-01
BACKGROUND: The risk of cerebral palsy, the commonest physical disability of children in western Europe, is higher in infants of very low birthweight (VLBW)--those born weighing less than 1500 g--and those from multiple pregnancies than in infants of normal birthweight. An increasing proportion...... of Cerebral Palsy in Europe, agreed a standard definition of cerebral palsy and inclusion and exclusion criteria. Data for children with cerebral palsy born in the years 1980-96 were pooled. The data were analysed to describe the distribution and prevalence of cerebral palsy in VLBW infants. Prevalence trends...... were expressed as both per 1000 livebirths and per 1000 neonatal survivors. FINDINGS: There were 1575 VLBW infants born with cerebral palsy; 414 (26%) were of birthweight less than 1000 g and 317 (20%) were from multiple pregnancies. 1426 (94%) had spastic cerebral palsy, which was unilateral...
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Wirestam, R.; Knutsson, L.; Risberg, J.; Boerjesson, S.; Larsson, E.M.; Gustafson, L.; Passant, U.; Staahlberg, F. [Depts. of Medical Radiation Physics, Diagnostic Radiology, Psychiatry, and Psychogeriatrics, Lund Univ, Lund (Sweden)
2007-07-15
Background: Attempts to retrieve absolute values of cerebral blood flow (CBF) by dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) have typically resulted in overestimations. Purpose: To improve DSC-MRI CBF estimates by calibrating the DSC-MRI-based cerebral blood volume (CBV) with a corresponding T1-weighted (T1W) steady-state (ss) CBV estimate. Material and Methods: 17 volunteers were investigated by DSC-MRI and 133Xe SPECT. Steady-state CBV calculation, assuming no water exchange, was accomplished using signal values from blood and tissue, before and after contrast agent, obtained by T1W spin-echo imaging. Using steady-state and DSC-MRI CBV estimates, a calibration factor K = CBV(ss)/CBV(DSC) was obtained for each individual. Average whole-brain CBF(DSC) was calculated, and the corrected MRI-based CBF estimate was given by CBF(ss) = KxCBF(DSC). Results: Average whole-brain SPECT CBF was 40.1{+-}6.9 ml/min 100 g, while the corresponding uncorrected DSC-MRI-based value was 69.2{+-}13.8 ml/mi 100 g. After correction with the calibration factor, a CBF(ss) of 42.7{+-}14.0 ml/min 100 g was obtained. The linear fit to CBF(ss)-versus-CBF(SPECT) data was close to proportionality (R = 0.52). Conclusion: Calibration by steady-state CBV reduced the population average CBF to a reasonable level, and a modest linear correlation with the reference 133Xe SPECT technique was observed. Possible explanations for the limited accuracy are, for example, large-vessel partial-volume effects, low post-contrast signal enhancement in T1W images, and water-exchange effects.
Okazawa, Hidehiko; Tsuchida, Tatsuro; Pagani, Marco; Mori, Tetsuya; Kobayashi, Masato; Tanaka, Fumiko; Yonekura, Yoshiharu
2006-01-01
To investigate the vasoconstrictor effect of 5-hydroxytryptamine (5-HT1B/1D) receptor agonists for migraine treatment, changes in cerebral blood flow (CBF) and blood volume induced by rizatriptan were assessed by positron emission tomography (PET). Eleven healthy volunteers underwent PET studies before and after rizatriptan administration. Dynamic PET data were acquired after bolus injection of H2(15)O to analyze CBF and arterial-to-capillary blood volume (V0) images using the three-weighted integral method. After a baseline scan, three further acquisitions were performed at 40 to 50, 60 and 70 to 80 mins after drug administration. Global and regional differences in CBF and V0 between conditions were compared using absolute values in the whole brain and cortical regions, as well as statistical parametric mapping (SPM) analysis. The global and regional values for CBF and V0 decreased significantly after rizatriptan administration compared with the baseline condition. However, both values recovered to baseline within 80 mins after treatment. The maximal reduction in global CBF and V0 was approximately 13% of baseline value. The greatest decrease in CBF was observed approximately 60 mins after drug administration, whereas the maximal reduction in V0 was observed approximately 5 mins earlier. Statistical parametric mapping did not highlight any regional differences between conditions. Thus, in brain circulation, rizatriptan caused significant CBF and V0 decreases, which are consistent with the vasoconstrictor effect of triptans on the large cerebral arteries. The gradual recovery in the late phase from the maximal CBF and V0 decrease suggests that rizatriptan does not affect the cerebral autoregulatory response in small arteries induced by CBF reduction.
Chihara, Izumi; Hayes, Donald K; Chock, Linda R; Fuddy, Loretta J; Rosenberg, Deborah L; Handler, Arden S
2014-07-01
To investigate the relationship between gestational weight gain (GWG) and birthweight outcomes among a low-income population in Hawaii using GWG recommendations from the 2009 Institute of Medicine (IOM) guidelines. Data were analyzed for 19,130 mother-infant pairs who participated in Hawaii's Special Supplemental Nutrition Program for Women, Infants, and Children from 2003 through 2005. GWG was categorized as inadequate, adequate, or excessive on the basis of GWG charts in the guidelines. Generalized logit models assessed the relationship between mothers' GWG and their child's birthweight category (low birthweight [LBW: < 2,500 g], normal birthweight [2,500 g ≤ BW < 4,000 g], or high birthweight [HBW: ≥ 4,000 g]). Final models were stratified by prepregnancy body mass index (underweight, normal weight, overweight, or obese) and adjusted for maternal age, education, race/ethnicity, smoking status, parity, and marital status. Overall, 62% of the sample had excessive weight gain and 15% had inadequate weight gain. Women with excessive weight gain were more likely to deliver a HBW infant; this relationship was observed for women in all prepregnancy weight categories. Among women with underweight or normal weight prior to pregnancy, those with inadequate weight gain during pregnancy were more likely to deliver a LBW infant. Among the low-income population of Hawaii, women with GWG within the range recommended in the 2009 IOM guidelines had better birthweight outcomes than those with GWG outside the recommended range. Further study is needed to identify optimal GWG goals for women with an obese BMI prior to pregnancy.
van Venrooij, Ger E. P. M.; van Melick, Harm H. E.; Eckhardt, Mardy D.; Boon, Tom A.
2008-01-01
OBJECTIVES To investigate the information of voiding data in relation to symptoms and well-being in men with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH) and to compare this information with that of prostate volume (Vprostate), maximal free urinary flow rate (
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Thomsen, H. (Den Sundhedsfaglige Kandidatuddannelse, Aarhus Universitet Bygning 1264, Aarhus (Denmark); University College Nordjylland, Aalborg (Denmark)), Email: hnt@ucn.dk; Steffensen, E. (Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark)); Larsson, E. M. (Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); Uppsala University Hospital, Department of Radiology, Uppsala (Sweden))
2012-02-15
Background. Perfusion magnetic resonance imaging (MRI) is increasingly used in the evaluation of brain tumors. Relative cerebral blood volume (rCBV) is usually obtained by dynamic susceptibility contrast (DSC) MRI using normal appearing white matter as reference region. The emerging perfusion technique arterial spin labelling (ASL) presently provides measurement only of cerebral blood flow (CBF), which has not been widely used in human brain tumor studies. Purpose. To assess if measurement of blood flow is comparable with measurement of blood volume in human biopsy-proven gliomas obtained by DSC-MRI using two different regions for normalization and two different measurement approaches. Material and Methods. Retrospective study of 61 patients with different types of gliomas examined with DSC perfusion MRI. Regions of interest (ROIs) were placed in tumor portions with maximum perfusion on rCBF and rCBV maps, with contralateral normal appearing white matter and cerebellum as reference regions. Larger ROIs were drawn for histogram analyses. The type and grade of the gliomas were obtained by histopathology. Statistical comparison was made between diffuse astrocytomas, anaplastic astrocytomas, and glioblastomas. Results. rCBF and rCBV measurements obtained with the maximum perfusion method were correlated when normalized to white matter (r = 0.60) and to the cerebellum (r = 0.49). Histogram analyses of rCBF and rCBV showed that mean and median values as well as skewness and peak position were correlated (0.61 < r < 0.93), whereas for kurtosis and peak height, the correlation coefficient was about 0.3 when comparing rCBF and rCBV values for the same reference region. Neither rCBF nor rCBV quantification provided a statistically significant difference between the three types of gliomas. However, both rCBF and rCBV tended to increase with tumor grade and to be lower in patients who had undergone resection/treatment. Conclusion. rCBF measurements normalized to white matter
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Samson Gebremedhin
Full Text Available BACKGROUND: The effects of prenatal Zinc Deficiency (ZD and Vitamin A Deficiency (VAD on birthweight are controversial and their interaction has not been investigated. OBJECTIVE: To assess the independent and interaction effects of prenatal zinc and vitamin A deficiencies on birthweight in rural Sidama, Southern Ethiopia. METHODOLOGY: A community-based prospective cohort study design was employed. Six hundred fifty pregnant women in their second or third trimester were randomly selected and their serum zinc and retinol concentrations were determined. About 575 subjects were successfully followed until delivery and birthweight was measured within 72 hours after delivery. The association between the exposures and birthweight was examined using log-binomial and liner regression analyses. Potential interaction between ZD and VAD was examined using Synergy Index (SI. RESULTS: The mean birthweight (± standard deviation was 2896 g (±423. About 16.5% (95% CI: 13.5-19.6% of the babies had Low Birthweight (LBW. Prenatal ZD and VAD were not significantly associated to LBW with Adjusted Relative Risk (ARR of 1.25 (95 CI: 0.86-1.82 and 1.27 (95% CI: 0.86-1.87, respectively. Stratified analysis on the basis of gestational trimester showed that the occurrence of the deficiencies neither in the second nor third trimester were associated to LBW. The deficiencies did not show synergetic interaction in causing LBW [SI = 1.04 (95% CI: 0.17-6.28]. Important risk factors of LBW were maternal illiteracy [RR = 1.80 (95% CI: 1.11-2.93], female sex of the newborn [RR = 1.79 (95% CI: 1.19-2.67], primiparity [RR = 1.16 (95% CI: 1.02-1.35], short maternal stature [RR = 1.63 (95% CI: 1.06-2.51] and maternal thinness [RR = 1.52 (95% CI: 1.03-2.25]. In the linear regression model, elevated CRP was also negatively associated to birthweight. CONCLUSION: LBW is of public health significance in the locality. The study did not witness any independent or
Kelly, Brian P.; Pickett, Linda L.; Hansen, Cristi V.; Ziegler, Andrew C.
2013-01-01
Arkansas River for the transient simulation is 7,916,564 cubic feet per day (91.6 cubic feet per second) and the RMS error divided by (/) the total range in streamflow (7,916,564/37,461,669 cubic feet per day) is 22 percent. The RMS error calculated for observed and simulated streamflow gains or losses for the Little Arkansas River for the transient simulation is 5,610,089 cubic feet per day(64.9 cubic feet per second) and the RMS error divided by the total range in streamflow (5,612,918/41,791,091 cubic feet per day) is 13 percent. The mean error between observed and simulated base flow gains or losses was 29,999 cubic feet per day (0.34 cubic feet per second) for the Arkansas River and -1,369,250 cubic feet per day (-15.8 cubic feet per second) for the Little Arkansas River. Cumulative streamflow gain and loss observations are similar to the cumulative simulated equivalents. Average percent mass balance difference for individual stress periods ranged from -0.46 to 0.51 percent. The cumulative mass balance for the transient calibration was 0.01 percent. Composite scaled sensitivities indicate the simulations are most sensitive to parameters with a large areal distribution. For the steady-state calibration, these parameters include recharge, hydraulic conductivity, and vertical conductance. For the transient simulation, these parameters include evapotranspiration, recharge, and hydraulic conductivity. The ability of the calibrated model to account for the additional groundwater recharged to the Equus Beds aquifer as part of the Aquifer Storage and Recovery project was assessed by using the U.S. Geological Survey subregional water budget program ZONEBUDGET and comparing those results to metered recharge for 2007 and 2008 and previous estimates of artificial recharge. The change in storage between simulations is the volume of water that estimates the recharge credit for the aquifer storage and recovery system. The estimated increase in storage of 1,607 acre-ft in the basin
The Association Between Hospital Obstetric Volume and Perinatal Outcomes in California
SNOWDEN, Jonathan M.; CHENG, Yvonne W.; KONTGIS, Caitlin; CAUGHEY, Aaron B.
2012-01-01
Objective To analyze the association between hospital obstetric volume and perinatal outcomes in California. Study Design This was a retrospective cohort study of births occurring in California in 2006. Hospitals were divided into four obstetric volume categories. Unadjusted rates of neonatal mortality and birth asphyxia were calculated for each category, overall and among term deliveries with birthweight >2500g. Multivariable logistic regression was used to control for confounders. Deliveries in rural hospitals were analyzed separately using different volume categories. Results Prevalence of asphyxia increased with decreasing hospital volume overall and among term, non-low-birthweight infants, from 9 per 10,000 live births at highest-volume hospitals to 18/10,000 live births at the lowest-volume hospitals (p<0.001). Similar trends were observed in rural hospitals, with rates increasing from 7 to 34 per 10,000 live births in low-volume rural hospitals (p<0.001). Conclusion These findings provide evidence for an inverse association between hospital obstetric volume and birth asphyxia. PMID:23174387
Characterization of miR-206 Promoter and Its Association with Birthweight in Chicken
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Xinzheng Jia
2016-04-01
Full Text Available miRNAs have been widely investigated in terms of cell proliferation and differentiation. However, little is known about their effects on bird growth. Here we characterized the promoter of miR-206 in chicken and found that the preferable promoter was located in 1200 bp upstream of pri-miR-206. In this region, many key transcription factors, including MyoD, c-Myb, CEBPα/β, AP-4, RAP1, Brn2, GATA-1/2/3, E47, Sn, upstream stimulatory factor (USF and CdxA, were predicted to bind and interact with miR-206 promoter. Overexpression of MyoD sharply increased miR-206 expression in both fibroblast and myoblast cells, and also the regulation in the myoblast cells was much stronger, indicating that miR-206 was regulated by MyoD combined with other muscle specific transcriptional factors. Aiming to further investigate the relationship between miR-206 mutation and transcriptional expression, total of 23 SNPs were identified in the two distinct bird lines by sequencing. Interestingly, the motif bound by MyoD was individually destroyed by G-to-C mutation located at 419 bp upstream of miR-206 precursor. Co-transfecting MyoD and miR-206 promoter in DF-1 cells, the luciferase activity of promoter containing homozygous GG types was significantly higher than CC ones (p < 0.05. Thus, this mutation caused low expression of miR-206. Consistently, eight variants including G-419C mutation exhibited a great effect on birthweight through maker-trait association analysis in F2 population (p < 0.05. Additionally, the regulation of miR-206 on embryo muscle mass mainly by increasing MyoG and muscle creatine kinase (MCK expression (p < 0.05 with little change in MyoD, TMEM8C and myosin heavy chain (MHC. In conclusion, our findings provide a novel mutation destroying the promoter activity of miR-206 in birds and shed new light to understand the regulation mechanism of miR-206 on the embryonic muscle growth.
Malaria, malnutrition, and birthweight: A meta-analysis using individual participant data.
Cates, Jordan E; Unger, Holger W; Briand, Valerie; Fievet, Nadine; Valea, Innocent; Tinto, Halidou; D'Alessandro, Umberto; Landis, Sarah H; Adu-Afarwuah, Seth; Dewey, Kathryn G; Ter Kuile, Feiko O; Desai, Meghna; Dellicour, Stephanie; Ouma, Peter; Gutman, Julie; Oneko, Martina; Slutsker, Laurence; Terlouw, Dianne J; Kariuki, Simon; Ayisi, John; Madanitsa, Mwayiwawo; Mwapasa, Victor; Ashorn, Per; Maleta, Kenneth; Mueller, Ivo; Stanisic, Danielle; Schmiegelow, Christentze; Lusingu, John P A; van Eijk, Anna Maria; Bauserman, Melissa; Adair, Linda; Cole, Stephen R; Westreich, Daniel; Meshnick, Steven; Rogerson, Stephen
2017-08-01
Four studies previously indicated that the effect of malaria infection during pregnancy on the risk of low birthweight (LBW; malaria infection and maternal anthropometric status on the risk of LBW using pooled data from 14,633 pregnancies from 13 studies (6 cohort studies and 7 randomized controlled trials) conducted in Africa and the Western Pacific from 1996-2015. Studies were identified by the Maternal Malaria and Malnutrition (M3) initiative using a convenience sampling approach and were eligible for pooling given adequate ethical approval and availability of essential variables. Study-specific adjusted effect estimates were calculated using inverse probability of treatment-weighted linear and log-binomial regression models and pooled using a random-effects model. The adjusted risk of delivering a baby with LBW was 8.8% among women with malaria infection at antenatal enrollment compared to 7.7% among uninfected women (adjusted risk ratio [aRR] 1.14 [95% confidence interval (CI): 0.91, 1.42]; N = 13,613), 10.5% among women with malaria infection at delivery compared to 7.9% among uninfected women (aRR 1.32 [95% CI: 1.08, 1.62]; N = 11,826), and 15.3% among women with low mid-upper arm circumference (MUAC malaria infection and low MUAC at enrollment compared to 8.4% among uninfected women with MUAC ≥ 23 cm (joint aRR 2.13 [95% CI: 1.21, 3.73]; N = 8,152). There was no evidence of synergism (i.e., excess risk due to interaction) between malaria infection and MUAC on the multiplicative (p = 0.5) or additive scale (p = 0.9). Results were similar using body mass index (BMI) as an anthropometric indicator of nutritional status. Meta-regression results indicated that there may be multiplicative interaction between malaria infection at enrollment and low MUAC within studies conducted in Africa; however, this finding was not consistent on the additive scale, when accounting for multiple comparisons, or when using other definitions of malaria and malnutrition. The major
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Onyiriuka Alphonsus N.
2015-12-01
Full Text Available A 16-year-old boy whose diabetes mellitus was diagnosed 3 months previously in a private hospital but was not placed on medication. The presenting complaints were fast breathing for 24 hours, weakness for 2 hours, and unresponsiveness to calls for 0.5 hours. His father was obese with type 2 diabetes mellitus and died 8 months earlier from cardiac arrest. His birthweight was low, 2.2kg. At first presentation, his weight, BMI and blood pressure were 60kg (25th-50th percentile, 19.4kg/m2 (25thpercentile and 110/70mmHg (systolic BP 50th percentile, diastolic BP 50th-90th percentile, respectively. He was managed for diabetic ketoacidosis and was discharged on subcutaneous premixed insulin, 1 Unit/kg/day. At point of discharge, weight and BP were 60.5 kg and 120/70 mmHg, respectively. The patient defaulted but presented again 6 months later at the age of 17 years. At second presentation, his weight, BMI and BP were 89 kg (95th percentile, 27.5 kg/m2 (90th-95th percentile and 180/80 mmHg (systolic 99th percentile; diastolic 90th percentile, respectively. His waist circumference was 98.7cm (> 90th percentile. We had no record of previous waist circumference. His lipid profile showed low HDL-cholesterol 0.7252 mmol/L [(28mg/dl; <5thpercentile]. His fasting blood glucose and HbA1C were 6.5 mmol/L (117mg/dl and 34 mol/mol (5.3%, respectively. A diagnosis of metabolic syndrome in a patient with ketosis-prone type 2 diabetes was made. He was referred to the pediatric cardiologist for management of his hypertension. He defaulted again and was lost to follow up. Conclusion: This report illustrates the association of low birth weight and rapid weight gain with metabolic syndrome in adolescence.
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Wiesmann, Martin [University of Munich, Department of Neuroradiology, Muenchen (Germany); Klinikum der Universitaet Muenchen - Grosshadern, Abteilung fuer Neuroradiologie, Muenchen (Germany); Berg, Scott; Stoeckelhuber, B.M. [University of Luebeck, Department of Radiology, Luebeck (Germany); Bohner, G.; Klingebiel, R. [University Medicine Berlin, Department of Neuroradiology, Charite, Berlin (Germany); Schoepf, V.; Yousry, I.; Linn, J. [University of Munich, Department of Neuroradiology, Muenchen (Germany); Missler, U. [Evangelisches Krankenhaus Duisburg-Nord, Department of Neuroradiology, Duisburg (Germany)
2008-12-15
The influence of the frequency of computed tomography (CT) image acquistion on the diagnostic quality of dynamic perfusion CT (PCT) studies of the brain was investigated. Eight patients with clinically suspected acute ischemia of one hemisphere underwent PCT, performed on average 3.4 h after the onset of symptoms. Sixty consecutive images per slice were obtained with individual CT images obtained at a temporal resolution of two images per second. Eight additional data sets were reconstructed with temporal resolutions ranging from one image per second to one image per 5 s. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) measurements were performed in identical regions of interest. Two neuroradiologists evaluated the PCT images visually to identify areas of abnormal perfusion. Perfusion images created up to a temporal resolution of one image per 3 s were rated to be diagnostically equal to the original data. Even at one image per 4 s, all areas of infarction were identified. Quantitative differences of CBF, CBV and MTT measurements were {<=}10% up to one image per 3 s. For PCT of the brain, temporal resolution can be reduced to one image per 3 s without significant compromise in image quality. This significantly reduces the radiation dose of the patient. (orig.)
Institute of Scientific and Technical Information of China (English)
Gang Guo; Yonggui Yang; Weiqun Yang
2011-01-01
The optimal velocity encoding of phase-contrast magnetic resonance angiography (PC MRA) in measuring cerebral blood flow volume (BFV) ranges from 60 to 80 cm/s. To verify the accuracy of two-dimensional (2D) PC MRA, the present study localized the region of interest at blood vessels of the neck using PC MRA based on three-dimensional time-of-flight sequences, and the velocity encodingwas set to 80 cm/s. Results of the measurements showed that the error rate was 7.0 ± 6.0%in the estimation of BFV in the internal carotid artery, the external carotid artery and the ipsilateralcommon carotid artery. There was no significant difference, and a significant correlation in BFV between internal carotid artery + external carotid artery and ipsilateral common carotid artery. Inaddition, the BFV of the common carotid artery was correlated with that of the ipsilateral internal carotid artery. The main error was attributed to the external carotid artery and its branches. Therefore,after selecting the appropriate scanning parameters and protocols, 2D PC MRA is more accuratein the determination of BFV in the carotid arteries.
Heijtel, D F R; Petersen, E T; Mutsaerts, H J M M; Bakker, E; Schober, P; Stevens, M F; van Berckel, B N M; Majoie, C B L M; Booij, J; van Osch, M J P; van Bavel, E T; Boellaard, R; Lammertsma, A A; Nederveen, A J
2016-04-01
The purpose of this study was to assess whether there was an agreement between quantitative cerebral blood flow (CBF) and arterial cerebral blood volume (CBVA) measurements by [(15)O]H2O positron emission tomography (PET) and model-free QUASAR MRI. Twelve healthy subjects were scanned within a week in separate MRI and PET imaging sessions, after which quantitative and qualitative agreement between both modalities was assessed for gray matter, white matter and whole brain region of interests (ROI). The correlation between CBF measurements obtained with both modalities was moderate to high (r(2): 0.28-0.60, P QUASAR significantly underestimated CBF by 30% (P QUASAR yielding values that were only 27% of the [(15)O]H2O-derived values (P QUASAR MRI, indicating similar qualitative CBVA and CBF information by both modalities. In conclusion, the results of this study demonstrate that QUASAR MRI and [(15)O]H2O PET provide similar CBF and CBVA information, but with systematic quantitative discrepancies. Copyright © 2016 John Wiley & Sons, Ltd.