bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steady, supercritical flow in collapsible tubes. Part 1. Experimental observations
Authors: Kececioglu Ifiyenia , Mcclurken Michael E. , Kamm Roger D. , Shapiro Ascher H. 
Published: April 2006

Experimental results are presented for steady, supercritical flow of a liquid in a thin-walled compliant tube which is in a state of partial collapse due to a negative transmural pressure. Particular attention is paid to the effects of longitudinal tension.With a constant external pressure, friction acts to increase the area in the down-stream direction. With the tube tilted downward, friction may be so balanced by gravity forces as to result in an asymptotic approach to an equilibrium situation in which the area and velocity remain constant. When the downstream pressure is increased sufficiently, shock-like transitions to subcritical inflated states, with positive transmural pressure, occur. The longitudinal length scale of the shock is on the order of one to several tube diameters. The pressure rise across the shock lies between that for loss-free pressure recovery and that given by the Borda-Carnot sudden-expansion theory.The presence of longitudinal tension causes a train of standing waves of area to appear upstream of a local area disturbance, such as a shock-like transition. The standing waves are superimposed upon the more gradual area changes associated with friction and gravity. The wave amplitude grows in the downstream direction. Theoretical interpretations of the observations are presented in the companion paper (part 2).
On characteristics of the water-particle velocity in a plunging breaker
Authors: Nakagawa Takeo 
Published: April 2006

Three velocity components of water particles in a plunging breaker over a horizontal step on the bed of a two-dimensional laboratory wave tank have been determined simultaneously by means of an elaborate flowmeter that measures the flow drag on three ‘tension threads’, with each recording a separate flow component.It is found that all three of the r.m.s. values in the plunging breaker become maximum at x/L ≈ 0·7, where x is the distance from the breaking point to the shore and L is the wavelength. It is found that both the velocity and r.m.s. values of the transverse flow component generated by the shoaling and wave breaking become comparable to those of the other two flow components.On the basis of spectral analyses it is found that major wave frequencies in both the longitudinal and vertical flow components of the original two-dimensional wave survive even after experiencing relatively strong shoaling and wave breaking, and part of the original wave energy is transferred to the transverse flow component and is located at these major frequencies. It is found that the majority of the higher-harmonic-frequency components (or turbulent fluctuations) are generated in the shoaling process and that the wave breaking provides a relatively minor contribution to the generation. Finally, it is found that, through the shoaling and wave breaking, the original wave energy is transported to a frequency range lower than the primary wave frequency (negative cascade), as well as to the higher frequency range (positive cascade) in each flow component.
Sedimentation in a dispersion with vertical inhomogeneities
Authors: Feuillebois Fran¸ois 
Published: April 2006

Statistical studies of hydrodynamic interactions between many particles in a dilute dispersion raise a problem of divergent integrals. This problem arises in particular when calculating the average velocity of sedimentation of solid spheres in a viscous fluid. The solution to this problem was given by Batchelor (1972) for monodisperse suspensions of spheres, on the basis of an assumption of homogeneity. This assumption is removed here. The problem of divergent integrals is reconsidered. The solution treats as successive steps:
the average flow due to random statistically independent point forces;the average flow due to random statistically independent solid spheres, without hydrodynamic interactions;the average sedimentation velocity of random, pairwise-dependent solid spheres with hydrodynamic interactions, in a dilute suspension.Considering the case of identical spheres, and assuming homogeneity in any horizontal plane, an expression is obtained for the average sedimentation velocity of a sphere in an otherwise inhomogeneous dispersion. The formula is written in terms of integrals involving probability distributions. It reduces, when the suspension is homogeneous, to a formula obtained by Batchelor.The probability distributions are not calculated in this paper. In order to evaluate numerically the average velocity of sedimentation, a simple expression for the pair distribution function is assumed, and two different concentration profiles are considered, viz. a sinusoidal variation and a step function. In the case of sinusoidal concentration wave, it is found that the contribution of the inhomogeneity is, for small wavelengths, comparable in magnitude to that calculated for a homogeneous dispersion by Batchelor (1972), i.e. –6.55c.The difference in velocity between the crest and trough of the wave is an increasing function of the wavelength. For a step function in concentration, particles at the top of the cloud start to fall faster, this effect being limited to a top layer about 10 radii thick.For future study of the long-term behaviour of a sedimenting cloud, the evolution of the pair distribution function should be added to the present theory.
Two-layer spin-up and frontogenesis
Authors: Linden P. F. , Heijst G. J. F. Van 
Published: April 2006

The spin-up of a two-layer fluid in a cylinder with a free surface and with a thin lower layer is examined in the laboratory. It is found that when the increase in rotation rate of the cylinder is large enough the radial outflow in the viscous boundary layer on the tank bottom is sufficient to cause the interface to descend near the centre of the tank and to intersect the bottom. The intersection between the interface and the bottom produces a front between stratified (two-layer) fluid and a central region (called the bare spot) in which the upper layer is in direct contact with the bottom. It is observed that the radius of the circular bare spot increases until the lower layer is spun up. Observations of the maximum size of the bare spot are compared with a theoretical calculation in which it is assumed that the lower layer acquires the new angular velocity of the container and where viscous coupling between the layers is neglected. An expansion in F, the upper-layer Froude number, gives good agreement with the observations.At larger times the circular front is observed to be unstable to frontal waves which appear to gain energy via baroclinic instability from the sloping density interface. At large amplitude these waves ‘break’, producing regions of closed streamlines in the upper layer. The shape of the bare spot is severely distorted by these waves and the associated motions. The effect of the bottom stress on the spin-up of the upper layer is found to be limited to the bare spot where it is in direct contact with the bottom. Some comments are made on the formation and decay of fronts in the benthic boundary layer of the ocean.
Axisymmetric Couette flow at large Taylor numbers
Authors: Townsend A. A. 
Published: April 2006

Measurements have been made in flow between concentric cylinders with only the inner one rotating, for Reynolds numbers (based on flow gap) from 17 000 to 120 000, corresponding to Taylor numbers from 8 × 107 to 4 × 109. At the lower speeds (Reynolds numbers less than 30 000), the large-scale motion consists of toroidal eddies, highly uniform in spacing and intensity and convected by a slow axial flow past fixed sensors. By synchronizing an external oscillator with the passage frequency, flow velocity and small-scale turbulent intensity may be sampled at defined stages of the passage cycle and averaged to provide maps of the velocity fields and the associated distributions of small-scale intensity and Reynolds stress.At higher speeds, the passage of toroidal eddies becomes too irregular to establish the passage cycle, but, by comparing the velocity fluctuations from four inclined hot wires placed near the outer cylinder, the current location of large-scale flow separation from the outer cylinder can be approximately determined. Statistics of the temporal variations of the location show that the large-scale motion still approximates to the toroidal form, but that there are azimuthal variations of separation position and velocity that indicate a change from toroidal to helical eddies. Conditional averages of flow velocity and small-scale turbulent intensity, based on relative distance from the position of flow separation, are very similar in form and magnitude to phase-selected averages obtained at lower speeds.The considerable changes in the large-scale motion that occur as the Reynolds number increases from 300 to 1200 times the critical value are believed to arise from increase in the ‘turbulent Taylor number’ of the central flow, based on variation of angular momentum and on the eddy diffusion coefficients for linear and angular momentum. Effects on the motion of the slow axial flow, always less than 1% of the peripheral flow velocity, are also discussed.
A note on the steady high-Reynolds-number flow about a circular cylinder
Authors: Peregrine D. H. 
Published: April 2006

The most detailed theoretical description of the steady flow at high Reynolds number about a circular cylinder is given by Smith (1979). It appears to give a satisfactory description of much of the flow field. Numerical solutions for this flow computed by Fornberg (1985) are in conflict with some aspects of Smith's model.An acknowledged weak point in Smith's argument is the lack of a detailed flow for the interior of the eddies, particularly with respect to their rear closure. This paper discusses this aspect of the flow with particular emphasis on the vorticity distribution and with the aid of a solution of the Navier–Stokes equations which is valid at the rear of the eddies. As a result an interpretation of Fornberg's results is possible. The self-induced velocity of translation of the vorticity distribution is considered and discussed with reference to the flow as Re → ∞.
Depressive symptoms and C-reactive protein: The Cardiovascular Risk in Young Finns Study
Authors: ELOVAINIO MARKO , KELTIKANGAS-JÄRVINEN LIISA , PULKKI-RÅBACK LAURA , KIVIMÄKI MIKA , PUTTONEN SAMPSA , VIIKARI LIISA , RÄSÄNEN LEENA , MANSIKKANIEMI KRISTIINA , VIIKARI JORMA , RAITAKARI OLLI T 
Published: April 2006

Background. We tested the hypothesis that depressive symptoms in healthy young adults would be associated with elevated levels of C-reactive proteins (CRP).Method. We studied the association between depressive symptoms and CRP in 1201 young adults, as a part of the on-going population-based Cardiovascular Risk in Young Finns Study. Depressive symptoms were determined by responses to a revised version of Beck's Depression Inventory in 1992 and 2001. CRP and other known cardiac risk factors were measured in 2001.Results. Higher depressive symptomatology in 1992 and in 2001 and their means score were related to higher CRP levels (B's range from 0·24 to 0·21, p<0·001). These relationships persisted after separate adjustments for various risk factors including sex, age, education, oral contraceptive use, dietary fat, physical activity, alcohol consumption, smoking status, LDL-cholesterol, HDL-cholesterol, systolic blood pressure and history of acute infectious disease. Adjustments for obesity and triglycerides levels, however, somewhat attenuated the relationship between depressive symptoms and CRP.Conclusions. We concluded that higher levels of depressive symptoms are associated with higher levels of CRP, but this association may largely be attributable to obesity or triglycerides.
The apoB/apoA‐I ratio: a strong, new risk factor for cardiovascular disease and a target for lipid‐lowering therapy – a review of the evidence
Authors: WALLDIUS G. , JUNGNER I. 
Published: April 2006

Abstract.During the last several years interest has focused on the importance of the lipid‐transporting apolipoproteins – apoB transports all potentially atherogenic very low‐density lipoprotein (VLDL), intermediate‐density lipoprotein (IDL) and LDL particles, and apoA‐I transports and acts as the major antiatherogenic protein in the HDL particles. The evidence for the apoB/apoA‐I ratio being a strong, new risk factor for cardiovascular (CV) disease and a target for lipid‐lowering therapy is reviewed. Results from clinical prospective studies and lipid‐lowering trials in healthy subjects and in patients with different clinical manifestations of atherosclerosis are reported. Risk of nonfatal and fatal myocardial infarction and stroke, and manifestations of atherosclerosis documented by angiographic, ultrasound and other techniques has been related to conventional lipids and apolipoproteins (apo). The cholesterol balance determined as the apoB/apoA‐I ratio has repeatedly been shown to be a better marker than lipids, lipoproteins and lipid ratios. The results indicate that the apoB/apoA‐I ratio is a simple, accurate and new risk factor for CV disease – the lower the apoB/apoA‐I ratio, the lower is the risk. Guidelines should be developed in order to recognize the important clinical risk information embedded in the apoB/apoA‐I ratio.
Assessment of abnormal glucose homeostasis and insulin resistance in Turkish obese children and adolescents
Authors: Atabek M. E. , Pirgon O. , Kurtoglu S. 
Published: April 2006

Background:  The worldwide increase in the prevalence of childhood obesity is reaching epidemic proportions and is associated with a dramatic rise in cases of type 2 diabetes. We determined the prevalence of impaired glucose regulation and insulin resistance in obese children and adolescents.Methods:  A total of 196 obese children [SD score (SDS) of body mass index (BMI): 2.17 ± 0.03], aged 7–18 years, including 86 male subjects, underwent an oral glucose tolerance test (1.75 g glucose/kg body weight). We used the modified WHO criteria adapted for children for abnormal glucose homeostasis. Homeostasis model assessment was used to estimate insulin resistance in all subjects. The insulin sensitivity index was also determined in subjects.Results:  Of the total of 196 obese children, 15 (6.6%) had an abnormal fasting glucose level. Of the 196 obese children, 35 (18%) had impaired glucose tolerance (IGT) and 83 (43%) had insulin resistance. Of the 196 obese children were six (3%) diagnosed with type 2 diabetes. Insulin resistance indices were correlated well with the degree of abnormal glucose tolerance.Conclusions:  IGT, insulin resistance and type 2 diabetes are far more common in obese Turkish children than previously thought. Early treatment in obese children and adolescents with IGT constitutes a strategy of reversing the progression to β‐cell failure and preventing type 2 diabetes.
Serum Lipids in the GENECARD Study of Coronary Artery Disease Identify Quantitative Trait Loci and Phenotypic Subsets on Chromosomes 3q and 5q
Authors: Shah S. H. , Kraus W. E. , Crossman D. C. , Granger C. B. , Haines J. L. , Jones C. J. H. , Mooser V. , Huang L. , Haynes C. , Dowdy E. , Vega G. L. , Grundy S. M. , Vance J. M. , Hauser E. R. 
Published: April 2006

SummaryCoronary artery disease (CAD) and dyslipidemia have strong genetic components. Heterogeneity complicates evaluating genetics of complex diseases such as CAD; incorporating disease‐related phenotypes may help reduce heterogeneity. We hypothesized that incorporating lipoproteins in a study of CAD would increase the power to map genes, narrow linkage peaks, identify phenotypic subsets, and elucidate the contribution of established risk factors to genetic results.We performed ordered subset analysis (OSA) and quantitative trait linkage (QTL) using serum lipoproteins and microsatellite markers in 346 families with early‐onset CAD. OSA defined homogeneous subsets and calculated lod scores across a chromosome after ranking families by mean lipoprotein values. QTL used variance components analysis. We found significantly increased linkage to chromosome 3q13 (LOD 5.10, p = 0.008) in families with higher HDL cholesterol, lower LDL and total cholesterol, lower triglycerides, and fewer CAD risk factors, possibly due to a concentrated non‐lipoprotein‐related genetic effect. OSA identified linkage on chromosome 5q34 in families with higher cholesterol, possibly representing a hereditary lipoprotein phenotype. Multiple QTLs were identified, with the strongest for: total cholesterol on chromosome 5q14 (LOD 4.3); LDL on 20p12 (LOD 3.97); HDL on 3p14 (LOD 1.65); triglycerides on 18q22 (LOD 1.43); and HDL/TC ratio on 3q27‐28 (LOD 2.06).Our findings suggest the presence of etiologic heterogeneity in families with early‐onset CAD, potentially due to differential effects of lipoprotein phenotypes. Candidate genes are under investigation.
Preparation of C-5 Substituted Cidofovir Derivatives
Authors: Krečmerová Marcela , Masojídková Milena , Holý Antonín 
Published: April 2006

1-[(S)-3-Hydroxy-2-(phosphonomethoxy)propyl]cytosine (HPMPC, cidofovir) was modified by substitution on the base moiety in positions C-5 andN4. Key intermediates of these syntheses, diisopropyl esters of (S)-1-[2-(phosphonomethoxy)-3-(triphenylmethoxy)propyl]-5-alkylcytosines (6and7) prepared from 5-alkyl-4-methoxypyrimidin-2(1H)-ones were transformed to the corresponding 5-substituted cytosine orN4-alkylcytosine derivatives by the action of ammonia or primary amines, respectively. These fully protected phosphonate esters gave by treatment with bromotrimethylsilane followed by hydrolysis free phosphonic acids: 1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]-5-methylcytosine (5-methyl-HPMPC,10), 5-ethyl-1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (5-ethyl-HPMPC,11) and a series of 5-ethyl-HPMPC analogues17-21bearing various substituents inN4position (cyclopropyl, cyclopentyl, 2-hydroxyethyl, allyl, 2-(dimethylamino)ethyl). 5-Ethynyl-1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (5-ethynyl-HPMPC,26) was prepared from 5-iodocytosine derivative23using Sonogashira coupling with (trimethylsilyl)acetylene, CuI and [PdCl2(Ph3P)2]. None of the prepared compounds exhibited antiviral activity in vitro.
Health status measurement in COPD: the minimal clinically important difference of the clinical COPD questionnaire
Authors: Kocks JWH , Tuinenga MG , Uil SM , van den Berg JWK , Ståhl E , van der Molen T 
Published: April 2006

Abstract

Background
Patient-reported outcomes (PRO) questionnaires are being increasingly used in COPD clinical studies. The challenge facing investigators is to determine what change is significant, ie what is the minimal clinically important difference (MCID). This study aimed to identify the MCID for the clinical COPD questionnaire (CCQ) in terms of patient referencing, criterion referencing, and by the standard error of measurement (SEM).

Methods
Patients were ≥40 years of age, diagnosed with COPD, had a smoking history of >10 pack-years, and were participating in a randomized, controlled clinical trial comparing intravenous and oral prednisolone in patients admitted with an acute exacerbation of COPD. The CCQ was completed on Days 1–7 and 42. A Global Rating of Change (GRC) assessment was taken to establish the MCID by patient referencing. For criterion referencing, health events during a period of 1 year after Day 42 were included in this analysis.

Results
210 patients were recruited, 168 completed the CCQ questionnaire on Day42. The MCID of the CCQ total score, as indicated by patient referencing in terms of the GRC, was 0.44. The MCID of the CCQ in terms of criterion referencing for the major outcomes was 0.39, and calculation of the SEM resulted in a value of 0.21.

Conclusion
This investigation, which is the first to determine the MCID of a PRO questionnaire via more than one approach, indicates that the MCID of the CCQ total score is 0.4.
Biologically relevant effects of mRNA amplification on gene expression profiles
Authors: van Haaften Rachel IM , Schroen Blanche , Janssen Ben JA , van Erk Arie , Debets Jacques JM , Smeets Hubert JM , Smits Jos FM , van den Wijngaard Arthur , Pinto Yigal M , Evelo Chris TA 
Published: April 2006

Abstract

Background
Gene expression microarray technology permits the analysis of global gene expression profiles. The amount of sample needed limits the use of small excision biopsies and/or needle biopsies from human or animal tissues. Linear amplification techniques have been developed to increase the amount of sample derived cDNA. These amplified samples can be hybridised on microarrays. However, little information is available whether microarrays based on amplified and unamplified material yield comparable results.
In the present study we compared microarray data obtained from amplified mRNA derived from biopsies of rat cardiac left ventricle and non-amplified mRNA derived from the same organ. Biopsies were linearly amplified to acquire enough material for a microarray experiment. Both amplified and unamplified samples were hybridized to the Rat Expression Set 230 Array of Affymetrix.

Results
Analysis of the microarray data showed that unamplified material of two different left ventricles had 99.6% identical gene expression. Gene expression patterns of two biopsies obtained from the same parental organ were 96.3% identical. Similarly, gene expression pattern of two biopsies from dissimilar organs were 92.8% identical to each other.
Twenty-one percent of reporters called present in parental left ventricular tissue disappeared after amplification in the biopsies. Those reporters were predominantly seen in the low intensity range.
Sequence analysis showed that reporters that disappeared after amplification had a GC-content of 53.7+/-4.0%, while reporters called present in biopsy- and whole LV-samples had an average GC content of 47.8+/-5.5% (P <0.001). Those reporters were also predicted to form significantly more (0.76+/-0.07 versus 0.38+/-0.1) and longer (9.4+/-0.3 versus 8.4+/-0.4) hairpins as compared to representative control reporters present before and after amplification.

Conclusion
This study establishes that the gene expression profile obtained after amplification of mRNA of left ventricular biopsies is representative for the whole left ventricle of the rat heart. However, specific gene transcripts present in parental tissues were undetectable in the minute left ventricular biopsies. Transcripts that were lost due to the amplification process were not randomly distributed, but had higher GC-content and hairpins in the sequence and were mainly found in the lower intensity range which includes many transcription factors from specific signalling pathways.
An integrated system for genetic analysis
Authors: Fiddy Simon , Cattermole David , Xie Dong , Duan Xiao Yuan , Mott Richard 
Published: April 2006

Abstract

Background
Large-scale genetic mapping projects require data management systems that can handle complex phenotypes and detect and correct high-throughput genotyping errors, yet are easy to use.

Description
We have developed an Integrated Genotyping System (IGS) to meet this need. IGS securely stores, edits and analyses genotype and phenotype data. It stores information about DNA samples, plates, primers, markers and genotypes generated by a genotyping laboratory. Data are structured so that statistical genetic analysis of both case-control and pedigree data is straightforward.

Conclusion
IGS can model complex phenotypes and contain genotypes from whole genome association studies. The database makes it possible to integrate genetic analysis with data curation. The IGS web site http://bioinformatics.well.ox.ac.uk/project-igs.shtml contains further information.