bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linear-eddy modelling of turbulent transport. Part 6. Microstructure of diffusive scalar mixing fields
Authors: Kerstein Alan R. 
Published: April 2006

The linear-eddy approach for modelling molecular mixing in turbulent flow involves stochastic simulation on a one-dimensional domain with sufficient resolution to include all physically relevant lengthscales. In each realization, molecular diffusion is implemented deterministically, punctuated by a sequence of instantaneous, statistically independent ‘rearrangement events’ (measure-preserving maps) representing turbulent stirring. These events emulate the effect of compressive strain on the scalar field. An inertial-range similarity law is incorporated.The model reproduces key features of scalar power spectra, including dependences of spectra! amplitudes and transition wavenumbers on Reynolds and Schmidt numbers. Computed scaling exponents governing scalar power spectra, higher-order fluctuation statistics such as structure functions, and the spatial distribution of scalar level crossings are close to measured exponents. It is inferred that the characterization of stirring as a sequence of independent events (the model analogue of eddies) leads to a useful representation of mixing-field microstructure.
Onset of three-dimensionality, equilibria, and early transition in flow over a backward-facing step
Authors: Kaiktsis Lambros , Karniadakis George Em , Orszag Steven A. 
Published: April 2006

A numerical study of three-dimensional equilibria and transition to turbulence in flow over a backward-facing step is performed using direct numerical solution of the incompressible Navier-Stokes equations. The numerical method is a high-order-accurate mixed spectral/spectral-element method with efficient viscous outflow boundary conditions. The appearance of three-dimensionality in nominally two-dimensional geometries is investigated at representative Reynolds numbers ranging from the onset of three-dimensional bifurcation to later transitional stages. Strongly three-dimensional regions are identified through standard correlation coefficients and new three-dimensionality indices, as well as through instantaneous and time-average streamline patterns and vorticity contours. Our results indicate that onset of three-dimensionality occurs at the boundaries between the primary and secondary recirculating zones with the main channel flow, the latter being the most stable flow component. There is. therefore, strong secondary instability in the shear layers, mainly due to the one emanating from the step corner.The flow further downstream is excited through the action of the upstream shear layers acquiring a wavy form closely resembling Tollmien–Schlichting waves both spatially and temporally with a characteristic frequency f1; upstream, at the shear layer another incommensurate frequency, f2, is present. The two-frequency flow locks-in to a single frequency if external excitations are imposed at the inflow at a frequency close to f1 or f2; the smaller amplitude excitations, however, may cause a strong quasi-periodic response. Such excitations may significantly increase or decrease (by more than 20%) the length of the primary separation zone XR at lock-in or quasi-periodic states. The equilibrium states resulting from the secondary instability at supercritical Reynolds numbers produce a flow modulated in the spanwise direction, with corresponding variations in the reattachment location XR. While three-dimensionality explains partially the discrepancy between numerical predictions and experimental results on XR at higher Reynolds number Re, the main source of discrepancy is attributed to the inflow conditions, and in particular to external disturbances superimposed on the mean flow, the latter being the main reason also for the somewhat earlier transition found in laboratory experiments.
Electroencephalographic Approximate Entropy Changes in Healthy Volunteers during Remifentanil Infusion
Authors: Noh Gyu-Jeong , Kim Kye-Min , Jeong Yong-Bo , Jeong Seong-Wook , Yoon Hee-Suk , Jeong Sung-Moon , Kang Sung-Hong , Linares Olinto , Kern Steven E. 
Published: April 2006

Background
The aim of this study was to investigate the independent effect of remifentanil on the approximate entropy (ApEn) in frontoparietal montages. The authors investigated which montages were relevant to assess the remifentanil effect on the electroencephalogram. Spectral edge frequency and the canonical univariate parameter were used as comparators.

Methods
Twenty-eight healthy volunteers were enrolled. With recording of the electroencephalogram at the F3, F4, Cz, P3, and P4 montages, remifentanil was infused at the rate of 1-8 mug . kg . min for 15-20 min. The relation between remifentanil concentration and the electroencephalographic parameters were tested by Spearman correlation. Signal-to-noise ratio, artifact robustness, coefficient of variation of the median baseline and maximal electroencephalographic effects, and ratio of average maximal electroencephalographic effect to interindividual baseline variability were measured. The performance of ApEn as an index of remifentanil effect site concentrations was tested by prediction probability.

Results
Approximate entropy showed significant correlation (R = -0.6465, P < 0.0001) with remifentanil concentration. It provided comparable signal-to-noise ratio, artifact robustness, and ratio of average maximal electroencephalographic effect to interindividual baseline variability to 95% spectral edge frequency. The coefficients of variation of the median baseline and maximal electroencephalo graphic effects were smallest in ApEn. Parietal montages showed higher ratios of average maximal electroencephalographic effect to interindividual baseline variability for all electroencephalographic parameters and lower coefficients of variation of the baseline values for ApEn and 95% spectral edge frequency than frontal montages. The prediction probability of ApEn was 0.7730.

Conclusions
Approximate entropy derived from a parietal montage is appropriate for the assessment of the remifentanil effect on the electroencephalogram.
A Genetic Analysis of Opioid-induced Hyperalgesia in Mice
Authors: Liang De-Yong , Liao Guochun , Wang Jianmei , Usuka Jonathan , Guo YingYing , Peltz Gary , Clark J David 
Published: April 2006

Background
Opioid-induced hyperalgesia (OIH) is a syndrome of increased sensitivity to noxious stimuli, seen after both the acute and chronic administration of opioids, that has been observed in humans and rodent models. This syndrome may reduce the clinical utility of opioids in treating acute and chronic pain.

Methods
In these studies, the authors measured the propensity of 15 strains of inbred mice to develop mechanical manifestations of OIH. These data were subjected to in silico genetic analysis, which resulted in the association of haplotypic blocks within or near several known genes. Both pharmacologic agents and transgenic mice were used to confirm the functional association of the most strongly linked gene with OIH.

Results
Both baseline mechanical nociceptive thresholds and the percentage changes in these thresholds after 4 days of morphine treatment were found to be highly strain dependent. The haplotypic blocks most strongly associated with the mechanical OIH data were located within the beta2 adrenergic receptor gene (beta2-AR). Using the selective beta2-AR antagonist butoxamine, the authors observed a dose-dependent reversal of OIH. Furthermore, deletion of the beta2-AR gene sharply reduced the mechanical allodynia present after morphine treatment in the wild-type mouse strain. Analysis of the associated beta2-AR haplotypic block identified single nucleotide polymorphisms potentially explaining in part the strain specific differences in OIH.

Conclusions
Genetic variants of the beta2-AR gene seem to explain some part of the differences between various strains of mice to develop OIH. The association of this gene with OIH suggests specific pharmacologic strategies for reducing the impact of OIH on patients consuming opioids.
Variability of the 13C‐Acetate Breath Test for Gastric Emptying of Liquids in Healthy Children
Authors: Hauser B. , De Schepper J. , Caveliers V. , Salvatore S. , Salvatoni A. , Vandenplas Y. 
Published: April 2006

ABSTRACTPurpose:Scintigraphy is considered as the “gold standard” for measuring gastric emptying (GE). The 13C‐acetate breath test (13C‐ABT) offers an attractive alternative to measure GE of liquids as it is nonradioactive. The aim of this study was to assess the variability of the 13C‐ABT for GE of liquids in healthy children using nondispersive infrared spectrometry (NDIRS).Methods:The 13C‐ABT was repeated at least 2 times in 21 healthy children (6 girls and 15 boys), aged between 6.2 and 16.4 years, 2 to 7 days apart. After an overnight fast, a standardized milk drink, labeled with 50 or 100 mg 13C‐acetate according to weight, was administered. Breath samples were taken before feeding, at 5‐minute intervals for the first 40 minutes and at 10‐minute intervals for the following 140 minutes after feeding. Breath samples were analyzed using NDIRS, and 13C recovery was used to calculate values for gastric half‐emptying time (t1/2), time of peak 13C exhalation, or gastric lag phase (tlag) and gastric emptying coefficient (GEC). Intraindividual variabilities of the parameters t1/2, tlag, and GEC were expressed as coefficient of intrasubject variation (CV).Results:The median CV of t1/2 was 8.3% (CV range, 1.6%‐16.2%; t1/2 interindividual range, 65‐112 minutes; and t1/2 intraindividual range, 4‐33 minutes). The median CV of tlag was 16.6% (CV range, 2.0%‐26.6%; tlag interindividual range, 31‐76 minutes; and tlag intraindividual range, 1‐35 minutes). The median CV of GEC was 4.3% (CV range, 0.8%‐15.7%; GEC interindividual range, 3.81‐4.89; GEC intraindividual range, 0.08‐1.31). The CVs of t1/2, tlag, and GEC were independent of age, sex, weight, height, and measured values of t1/2, tlag, and GEC.Conclusions:The 13C‐ABT using NDIRS is an easy, noninvasive, and nonradioactive procedure with a large intraindividual variation for measuring GE of liquids in healthy children, but comparable to the variation reported with other techniques.
Immunization status of children under 7 years in the Vikas Nagar area, North India
Authors: Elliott C. , Farmer K. 
Published: April 2006

AbstractBackground  Immunization has played a major part in reducing childhood morbidity and mortality worldwide. Knowledge of vaccine coverage and reasons for poor uptake are essential for the achievement of herd immunity.Method  An observational study was carried out in September 2003, in 10 villages in the Vikas Nagar area around Herbertpur Christian Hospital in Uttaranchal, North India. We aimed to assess vaccination rates and potential socio‐cultural, economic and religious influences on vaccine uptake. A total of 470 families were visited and details of immunization status of the oldest child under 7 years in each household were taken. Age range of children included was 9 months to 6 years.Results  The overall primary immunization rate was 77.2%, children receiving the first booster was 73.1% and children receiving the second booster was 58.4%. The most common vaccinations to be missed were the diphtheria, pertussis, tetanus at 18 months and diphtheria, tetanus at 5 years. Measles was the most frequently omitted vaccination in the primary course (19.4%). Poor education was the most frequent reason given by parents for failure to vaccinate. Immunization rates did not differ according to gender of the child. A lower immunization rate was found in Muslim families (65.4% primary) compared with Hindu (85.2%). Parental literacy had a beneficial effect such that up to 20% more children were immunized.Conclusion  These results highlight the potential importance of literacy, and religious or cultural influences on the success of the Expanded Programme of Immunization, and will have important implications for areas with similar cultural demographics.
Spreading introgression in the wake of a moving contact zone
Authors: SECONDI JEAN , FAIVRE BRUNO , BENSCH STAFFAN 
Published: April 2006

AbstractAn increasing number of studies describe moving hybrid zones. This raises the issue of their actual frequency and emphasizes the need for methods that enable the detection of zone movements without historical records. Asymmetric introgression, usually considered as a signature of geographical shift, might be misleading when applied to mitochondrial or potentially non‐neutral markers. We investigated mitochondrial and genomic introgression, using 30 AFLP derived markers, in a well‐documented moving avian contact zone between two warblers. We found no instances of cross‐species transmission of mitochondrial DNA but we detected nuclear introgression. Introgression levels were higher in the expanding species. Highest introgression was observed in populations that recently became allopatric than in current sympatric populations, which suggests that alien genetic material mainly spread at the time just before the receding species became extinct. We propose that either local recruitment or positive selection on some loci contribute to this pattern. Furthermore, we propose that, when the rarefaction of sexual partners drive the hybridization process, movement could be revealed by introgression peaking on the rear edge of the moving zone, or in its close vicinity.
Reduction of Botrytis cinerea sporulation in sweet basil by altering the concentrations of nitrogen and calcium in the irrigation solution
Authors: Yermiyahu U. , Shamai I. , Peleg R. , Dudai N. , Shtienberg D. 
Published: April 2006

Current measures for suppressing grey mould (Botrytis cinerea) on sweet basil rely on fungicide applications and climate control. In this study, the nitrogen and calcium concentrations in the standard irrigation solution (7·2 and 1·3 mm, respectively) were varied in a series of experiments conducted in pots and large containers. Treatments differed in the N or Ca concentrations supplied, and effects on host response were determined in detached stem segments, individual plants and plots. Effects of the two elements on grey mould incidence, lesion size and rate of disease progression were erratic and rarely significant, but decreasing the concentration of N and increasing the concentration of Ca in the irrigation solution decreased sporulation of B. cinerea. In some cases, however, altering the standard irrigation solution resulted in significantly lower yields. Analyses of mineral contents in the shoots suggested that yields were not impaired when N content in the shoots was not reduced below 2·9% and Ca content was not raised above 1·3%. These findings were used to compose a modified irrigation solution containing half of the N (3·6 mm) and double of the Ca (2·55 mm) concentrations in the standard irrigation solution. The modified irrigation solution significantly reduced sporulation of B. cinerea without affecting crop yield.
Expression of Idiotypic Antibodies‐1 and ‐2 and Breastfeeding in Relation to Antibody Levels Against Haemophilus Influenzae Type b in Children
Authors: Silfverdal S. A. , Bodin L. , Ulanova M. , Hahn‐Zoric M. , Hanson L. Å. , Olcén P. 
Published: April 2006

AbstractThe aim of the study was to determine the concentrations of serum antibodies against Haemophilus influenzae type b in preschool children in relation to the distribution of idiotypic antibodies 1 and 2 (Id‐1 and Id‐2) and the exposure to breastfeeding in infancy. Sera were obtained from 74 control children recruited in an earlier case‐control study before the introduction of general Hib vaccination. Duration of breastfeeding was monitored, and prevalence of noninvasive infections was registered. Concentrations of IgG1 and IgG2 anti‐Hib, as well as of total Id‐1 and Id‐2, were determined in ELISA. The expression of Id‐1 antibodies increased with age in contrast to the Id‐2 antibodies that were found only in children up to 24 months of age. Expression of Id‐1 antibodies was positively correlated with higher anti‐Hib levels of both the IgG1 and IgG2 isotype. Children expressing Id‐2 antibodies showed higher IgG2 anti‐Hib concentrations than those who did not have Id‐2 (P = 0.001). The concentrations of neither Id‐1 nor Id‐2 antibodies were related to the duration of breastfeeding. Duration of breastfeeding was related to increased anti‐Hib IgG2 in healthy children above 18 months of age. These study shows that the expression of idiotype‐1 and idiotype‐2 antibodies was associated with higher IgG2 anti‐Hib concentration and that breastfeeding could enhance the anti‐Hib IgG2 production in children.
Interleukin‐6 Trans‐Signalling in Chronic Inflammation and Cancer
Authors: Scheller J. , Ohnesorge N. , Rose‐John S. 
Published: April 2006

AbstractInterleukin‐6 (IL‐6) is a cytokine, which plays an important role in many chronic inflammatory diseases. IL‐6 belongs to a family of 10 cytokines, which all act via receptor complexes containing the cytokine receptor subunit gp130. On cells, IL‐6 first binds to a specific membrane‐bound IL‐6R and the complex of IL‐6 and IL‐6R interacts with gp130 leading to signal initiation. Whereas gp130 is widely expressed throughout the body, the IL‐6R is only found on some cells including hepatocytes and some leucocytes. A soluble form of the IL‐6R is an agonist capable of transmitting signals through interaction with the gp130 protein. In vivo, the IL‐6/soluble IL‐6R complex stimulates several types of target cells, which are unresponsive to IL‐6 alone, as they do not express the membrane‐bound IL‐6R. We have named this process trans‐signalling. We provided evidence that a soluble form of the IL‐6 family signalling receptor subunit gp130 is the natural inhibitor of IL‐6 trans‐signalling responses. We showed that in chronic inflammatory diseases such as inflammatory bowel disease, peritonitis, rheumatoid arthritis, asthma as well as in colon cancer, IL‐6 trans‐signalling is critically involved in the maintenance of the disease state. Moreover, in all these animal models, the progression of the disease can be interrupted by specifically interfering with IL‐6 trans‐signalling using recombinant‐soluble gp130Fc protein. The pathophysiologic mechanisms by which the IL‐6/soluble IL‐6R complex perpetuates the inflammatory state are discussed.
Comparative efficacy of chloroquine and sulphadoxine – pyrimethamine in pregnant women and children: a meta‐analysis
Authors: Kalanda Gertrude C. , Hill Jenny , Verhoeff Francine H. , Brabin Bernard J. 
Published: April 2006

SummaryObjective  To compare the efficacy of chloroquine and sulphadoxine–pyremethamine against Plasmodium falciparum infection in pregnant women and in children from the same endemic areas of Africa, with the aim of determining the level of correspondence in efficacy determinations in these two risk groups.Methods  Meta‐analysis of nine published and unpublished in vivo antimalarial efficacy studies in pregnant women and in children across five African countries.Results  Pregnant women (all gravidae) were more likely to be sensitive than children to both chloroquine (odds ratio: 2.07; 95% confidence interval: 1.5, 2.9) and sulphadoxine–pyrimethamine (odds ratio: 2.66; 95% confidence interval: 11.1, 6.7). Pregnant women demonstrated an almost uniform increased sensitivity for peripheral parasite clearance at day 14 compared with children. This finding was consistent across a wide range of drug sensitivities. Primigravidae at day 14 showed lower clearance to antimalarial drugs than multigravidae (P < 0.05). There was no significant difference between parasite clearance in primigravidae and in children.Conclusion  The greater drug sensitivity in pregnant women probably indicates differences in host susceptibility rather than parasite resistance. Parasite sensitivity patterns in children may be a suitable guide to antimalarial policy in pregnant women.
Circumsporozoite protein gene diversity among temperate and tropical Plasmodium vivax isolates from Iran
Authors: Zakeri Sedigheh , Abouie Mehrizi Akram , Djadid Navid Diparast , Snounou Georges 
Published: April 2006

SummaryTo date, there is no information on the genetic diversity of the circumsporozoite protein (CSP), a leading vaccine candidate, in Plasmodium vivax populations circulating in Iran. The gene for this protein, Pvcsp, was amplified from 374 P. vivax isolates collected in the temperate northern, and in the tropical southern endemic areas. PCR–RFLP analysis of the repeated central region revealed that the parasites collected in the northern area were almost exclusively of the VK210 type. Parasites collected in the south‐eastern areas were of both VK210 and VK247 types. We detected VK210 parasite in 70.5% of the samples, VK247 parasites in 17.5% and mixed type infections in 12% of the isolates. Sequence analysis of 137 isolates obtained from both areas identified a total of 25 distinct genotypes. The degree of genetic diversity was generally higher for the tropical (21 genotypes) than the temperate (7 genotypes) P. vivax populations, a difference possibly reflecting the high cross‐border exchanges between Afghanistan and Pakistan and southern Iran. Interestingly, all but two VK210 type isolates sequenced harboured a 36‐bp post‐repeat insert previously only observed in North Korea and China. This large‐scale survey of parasite diversity in the Eastern Mediterranean Region provides a set of baseline data suitable for future molecular epidemiological studies of P. vivax.
Accuracy of resource selection functions across spatial scales
Authors: Meyer Carolyn B. , Thuiller Wilfried 
Published: April 2006

ABSTRACTResource selection functions (RSFs) can be used to map suitable habitat of a species based on predicted probability of use. The spatial scale may affect accuracy of such predictions. To provide guidance as to which spatial extent or grain is appropriate and most accurate for animals, we used the concept of hierarchical selection orders to dictate extent and grain. We conducted a meta‐analysis from 123 RSF studies of 886 species to identify differences in prediction success that might be expected for five selection orders. Many studies do not constrain spatial extent to the grain of the next broader selection order in the hierarchy, mixing scaling effects. Thus, we also compared accuracy of single‐ vs. multiple‐grain RSFs developed at the unconstrained extent of an entire study area. Results suggested that the geographical range of a species was the easiest to predict of the selection orders. At smaller scales within the geographical range, use of a site was easier to predict when environmental variables were measured at a grain equivalent to the home‐range size or a microhabitat feature required for reproduction or resting. Selection of patches within home ranges and locations of populations was often more difficult to predict. Multiple‐grain RSFs were more predictive than single‐grain RSFs when the entire study area was considered available. Models with variables measured at both small and large (> 100 ha) grains were usually most predictive, even for many species with small home ranges. Multiple‐grain models may be particularly important for species with moderate dispersal abilities in habitat fragments surrounded by an unsuitable matrix. We recommend studies should no longer address only one grain to map animal species distributions.