bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sonographic demonstration of brain injury in fetuses with severe red blood cell alloimmunization undergoing intrauterine transfusions
Authors: Ghi T. , Brondelli L. , Simonazzi G. , Valeri B. , Santini D. , Sandri F. , Ancora G. , Pilu G. 
Published: April 2004

AbstractObjectiveTo assess sonographically brain anatomy in fetuses with severe anemia due to red blood cell alloimmunization undergoing intrauterine intravascular transfusions.MethodsMultiplanar neurosonography was performed in seven consecutive hydropic fetuses undergoing intrauterine transfusions (mean gestational age 22 ± 2.5 weeks; mean hemoglobin concentration at the first transfusion 2.3 ± 1.0 g/dL).ResultsAbnormal cerebral findings were identified in four out of seven fetuses. An intracerebellar hemorrhage developed in two fetuses after the first transfusion and one fetus that had severe brain edema before the first transfusion was later found to have cystic periventricular leukomalacia. In one fetus unilateral ventriculomegaly was noted after the first transfusion. Two fetuses were terminated. The remaining pregnancies had an uneventful course, the infants were delivered between 34 and 36 gestational weeks and were alive and well at the time of writing. Prenatal diagnosis of brain injury was always confirmed except for the case with ventriculomegaly that underwent spontaneous intrauterine resolution.ConclusionsFetuses with extreme anemia due to red blood cell alloimmunization can be salvaged by intrauterine transfusion. In some of these cases brain injury may occur prenatally, and the risk seems to be particularly high when the hemoglobin concentration at the time of the first transfusion is ≤ 2 g/dL. We suggest that in these pregnancies detailed fetal neuroimaging by either multiplanar sonography and/or magnetic resonance imaging is indicated. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Tailored management of twin reversed arterial perfusion (TRAP) sequence
Authors: Weisz B. , Peltz R. , Chayen B. , Oren M. , Zalel Y. , Achiron R. , Lipitz S. 
Published: April 2004

AbstractObjectiveTo describe our management of pregnancies complicated by twin reversed arterial perfusion (TRAP) sequence.MethodsThis was a retrospective study involving all cases of TRAP sequence referred to our fetal medicine unit in a 3‐year period (2000–2002). Patients were routinely managed by repeat sonographic surveillance with sonographic anatomical evaluation and detailed echocardiography. Cases with signs of impending cardiac failure were treated by in‐utero YAG‐laser coagulation of the umbilical vessels of the acardiac twin.ResultsSix cases were studied. Three patients in whom there were no signs of deterioration in the status of the pump twin, and in whom the acardiac twin was smaller than the pump twin, were managed conservatively. However, one of these with monoamniotic twins ended in intrauterine fetal death of the pump twin. The other two cases presented with spontaneous cessation of blood flow in the umbilical artery of the acardiac twin. Both delivered at term normal neonates whose follow‐up revealed no signs of neurological sequelae. One case of quadruplet pregnancy (with TRAP sequence and two dichorionic twins) was treated by selective termination of the monochorionic twins. Two cases with signs of impending cardiac failure were treated by in‐utero YAG‐laser occlusion of the vessels in the acardiac mass. Both interventions had a favorable outcome.ConclusionsConservative treatment is suitable for milder cases of TRAP sequence in which the pump twin is the larger one. Cases in which the acardiac twin is larger have a poorer prognosis and should be treated by invasive intervention and cord occlusion. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
On the autocorrelation and the triple correlation equation for complex‐valued signals
Authors: v. Wolfersdorf L. 
Published: April 2004

AbstractThe paper deals with the autocorrelation equation on a finite interval and on the half‐axis and with the triple correlation equation in the case of complex‐valued signals. Via methods of Fourier transformation the equations are reduced to boundary value and continuation problems for holomorphic functions in the upper half‐plane and to functional equations in two independent variables, respectively, and in this way solved in closed form. Thereby, on the one side, Cauchy integrals and Paley‐Wiener conditions and, on the other side, the solution of a known functional equation in a single variable are applied.
Global existence of solutions of the Dirichlet problem for the compressible Navier‐Stokes equations
Authors: Mucha P.B. , Zaja̧czkowski W.M. 
Published: April 2004

AbstractWe prove the existence of global in time regular solutions of the compressible Navier‐Stokes equations in a domain Ω ⊂ R3 with vanishing Dirichlet boundary conditions. The solutions are close to nontrivial static solutions. A key element of the proof is a special Lp‐estimate for the linearized problem to show that the velocity belongs to W2,1r(loc)(Ω × [0,∞)) with r > 3 which is the sharp result in this approach.
Reynolds‐stress balance equations in orthogonal helical coordinates and application
Authors: Hüttl T.J. , Chaudhuri M. , Wagner C. , Friedrich R. 
Published: April 2004

AbstractRecently, direct numerical simulations of turbulent flow in helically coiled pipes have been performed and published. Here, computational results are shown for low Reynolds number flow (Reτ = 230) through one helical pipe configuration (curvature κ R = 0.1, torsion τ R = 0.165). The results are shortly discussed and further information of other toroidal or helical pipe flow simulations are given. Besides, the Reynolds‐stress balance equations derived in orthogonal helical coordinates are presented to allow further insight into helical pipe flow. The Reynolds‐stress balance equations are of great importance for turbulence modelling. Compared to their formulation in cylindrical coordinates, further terms occur, describing centrifugal and other inertia force effects which result from pipe curvature and torsion. Except for toroidal flow, where torsion is zero and a symmetry plane exists, no possibility to simplify the equations has been found.
Competition between domestic livestock and wild bharal Pseudois nayaur in the Indian Trans‐Himalaya
Authors: Mishra Charudutt , Van Wieren Sipke E. , Ketner Pieter , Heitkönig Ignas M. A. , Prins Herbert H. T. 
Published: April 2004

Summary

The issue of competition between livestock and wild herbivores has remained contentious. We studied the diets and population structures of the mountain ungulate bharal Pseudois nayaur and seven species of livestock to evaluate whether or not they compete for forage. The study was conducted in the high altitude Spiti Valley, Indian Trans‐Himalaya.
We compared resource (forage) availability and bharal population structures between rangelands differing in livestock density. Forage availability was estimated by clipping the standing graminoid biomass in sample plots. Livestock and bharal population structures were quantified through annual censuses. Seasonal diets of livestock were studied by direct observations, while those of bharal were quantified through feeding signs on vegetation.
We found that livestock grazing causes a significant reduction in the standing crop of forage. Graminoid availability per unit livestock biomass was three times greater in a moderately grazed rangeland compared with an intensively grazed one.
There was considerable diet overlap among the herbivore species. In summer, bharal, yak Bos grunniens, horse Equus caballus, cow Bos indicus, and dzomo (yak–cow hybrids) fed predominantly on graminoids, while donkey E. asinus, sheep Ovis aries, and goat Capra hircus, consumed both graminoids and herbs. The summer diet of bharal was a subset of the diets of three livestock species. In winter, depleted graminoid availability caused bharal, yak and horse to consume relatively more herbs, while the remaining livestock species fed predominantly on graminoids. Diet overlap was less in winter but, in both seasons, all important forage species in the bharal diet were consumed in substantial amounts by one or more species of livestock.
Comparison of the population structures of bharal between two rangelands differing in livestock density by c. 30% yielded evidence of resource competition. In the intensively grazed rangeland, bharal density was 63% lower, and bharal population showed poorer performance (lower young : adult female ratios).
Synthesis and applications. High diet overlap between livestock and bharal, together with density‐dependent forage limitation, results in resource competition and a decline in bharal density. Under the present conditions of high livestock density and supplemental feeding, restricting livestock numbers and creating livestock‐free areas are necessary measures for conserving Trans‐Himalayan wild herbivores. Mediating competitive effects on bharal through supplemental feeding is not a feasible option.
The dynamics of hunted Icelandic goose populations: a reassessment of the evidence
Authors: Frederiksen Morten , Hearn Richard D. , Mitchell Carl , Sigfússon Arnór , Swann Robert L. , Fox Anthony D. 
Published: April 2004

Summary

Migratory geese are dominant terrestrial herbivores in Arctic and north temperate regions. They are important quarry species and also conflict with agricultural interests through winter foraging. We investigated the dynamics of the populations of greylag Anser anser and pink‐footed Anser brachyrhynchus geese that breed in Iceland and winter in Britain.
We estimated seasonal and annual survival of both populations based on colour‐ringing programmes in Iceland 1996–2000 and in Britain since 1987. We used these results, along with hunting bag statistics from Iceland, in a set of models to assess the British autumn counts as well as the impact of hunting.
After a rapid increase, the pink‐footed goose counts stabilized after 1992 at around 230 000. The greylag goose counts increased slowly to c. 100 000 around 1990 and then declined to around 80 000. Both populations showed stable counts from 1996 to 2000, when the proportion of young recorded in autumn was 17·5% for greylag geese and 18·2% for pink‐footed geese. Hunting bag statistics have been compiled since 1995 in Iceland; during 1996–2000, means of 36 608 greylag geese and 13 991 pink‐footed geese were reported shot annually.
Mean annual adult and first‐year survival estimates were 0·727 and 0·472 for greylag geese, and 0·814 and 0·394 for pink‐footed geese. The lower survival of juvenile pink‐footed geese was probably due to higher natural mortality, whereas the generally lower survival of greylag geese could be explained by higher hunting pressure.
Simple modelling showed that the results from autumn surveys and bag statistics were incompatible for greylag geese. For the population to remain stable with the estimated survival rate, the proportion of juveniles in autumn must be 30%. We suggest that problems in separating juveniles from adults in October–November caused the lower proportion of juveniles recorded. Also, the number of greylag geese counted in autumn and the number reported shot in Iceland cannot both be correct; the bag statistics imply a population twice as large as the number counted. Large numbers of greylag geese may winter in areas not covered by the autumn census, but overreporting of the hunting bag may also have occurred. No such discrepancies were found for pink‐footed geese.
Synthesis and applications. We recommend that a stratified sampling programme be established for estimating the size and age composition of both goose species. The age composition of greylag geese can profitably be studied in Iceland in August, when juveniles are easily recognizable. Ringing should be continued as a tool for monitoring survival, and a hunting bag survey should be implemented in Britain. In general, the reliability of population surveys should always be tested with independent data.
Reproductive success of hatchery‐produced and wild‐born brown trout in an experimental stream
Authors: Dannewitz Johan , Petersson Erik , Dahl Jonas , Prestegaard Tore , Löf Anna‐Carin , Järvi Torbjörn 
Published: April 2004

Summary

Although releases of hatchery‐produced salmonids to support conspecific wild populations have increased dramatically during recent decades, little information is available about the performance in the wild of hatchery fish and their offspring. Important factors determining the success and genetic outcomes of supportive breeding programmes include (i) the relative reproductive success of released hatchery fish in the wild, and (ii) the extent to which the propagation affects the variance in reproductive success in the population as a whole.
We performed two field experiments on brown trout Salmo trutta from the River Dalälven in Sweden, where we examined reproductive success in an experimental stream. In experiment 1 we compared reproductive success between trout from a seventh‐generation hatchery stock of native origin and wild‐born trout from the river. In experiment 2, we compared reproductive success between seventh‐generation hatchery trout and hatchery‐reared trout derived from wild‐born parents. Individual reproductive success, based on the number of offspring assigned using microsatellite markers, was assessed on three occasions after reproduction: immediately after hatching and after the first and second growth seasons.
In experiment 1 there were no significant differences in reproductive success between seventh‐generation hatchery trout and wild‐born trout. In experiment 2, males from wild‐born parents were more successful than males from the seventh‐generation hatchery stock, but this difference was not observed among females.
There was some evidence for a positive association between body size and reproductive success among females but not males. For males, the number of mates was significantly associated with reproductive success, but this relationship was not evident among females.
The variance in reproductive success was pronounced in both experiments, yielding estimates of the ratio between the genetically effective size and the census size of our experimental populations ranging from 0·12 to 0·59.
Synthesis and applications. Our results suggest that the reproductive success in the wild of hatchery‐produced and wild‐born trout with a common genetic background may be rather similar. These findings, in combination with the pronounced variance in reproductive success observed among breeders, indicate that supportive breeding can be managed to increase not only the census but also the genetically effective size of small, endangered salmonid populations. However, to minimize negative effects of hatchery selection, it is important to give priority to the restoration of natural habitats and thereby increase the reproductive output from individuals in the wild.
A quantitative approach to conservation planning: using resource selection functions to map the distribution of mountain caribou at multiple spatial scales
Authors: Johnson Chris J. , Seip Dale R. , Boyce Mark S. 
Published: April 2004

SummaryVisualizing the distribution of rare or threatened species is necessary for effective implementation of conservation initiatives. Generalized linear models and geographical information systems (GIS) are now powerful tools for conservation planning, but issues of data availability, scale and model extrapolation complicate some applications.Mountain caribou are an endangered ecotype of woodland caribouRangifer tarandus caribouthat occurs across central and southern British Columbia, Canada. Currently, conservation professionals use coarse small‐scale maps of important habitats to manage forest harvesting and human access across the northern extent of mountain caribou range. These maps were produced before the advent of readily available digital spatial information and are based on expert opinion and limited empirical data.With the purpose of refining existing maps, we used survey results, radio‐telemetry locations and GIS data to construct resource selection functions (RSF) that quantified the habitat affinities and predicted the relative probability of occurrence of mountain caribou at two spatial scales. At the scale of the patch, the most parsimonious RSF model consisted of covariates for vegetation and aptly predicted the occurrence of caribou across low‐ to mid‐elevation habitats, but performed poorly across steep alpine terrain. At the landscape scale, a model containing Gaussian terms for elevation and slope was effective at predicting the broader distribution of caribou.We produced a map consisting of the product of the relative probabilities of the patch and landscape RSF. The final map represented the relative probability of occurrence of caribou in vegetative patches weighted by the relative probability of occurrence across the larger study area. We found strong agreement between current definitions of important caribou habitats developed from expert opinion and RSF‐based maps generated from empirical data.Synthesis and applications. Both expert opinion and RSF‐based approaches offer unique advantages for conservation mapping. Interpretability of results, documentation and repeatability of methods and data, estimates of precision and costs should all be considered when evaluating a technique. We argue that for some species and geographical locations, RSF is a superior technique, but expert opinion should play a role in model development and interpretation.
Human disturbance: people as predation‐free predators?
Authors: Beale Colin M. , Monaghan Pat 
Published: April 2004

Summary

Human disturbance has been associated with declines in breeding success in numerous species and is of general concern to conservationists. However, the current framework for predicting and minimizing disturbance effects is weak and there is considerable uncertainty about why animals are disturbed by people in the first place.
We developed a behavioural model of perceived predation risk as a framework for understanding the effects of disturbance on cliff‐nesting birds. This encompassed the concept that the effects of disturbance should increase with increasing numbers of visitors, and decrease with distance from the nest, an insight ignored in current conservation practice.
The predictions of this model were tested using field data on nesting success in two species of seabird, kittiwake Rissa tridactyla and guillemot Uria aalge. Statistical models of nesting success in both species suggested that perceived predation risk is a good predictor of the effects of disturbance.
Synthesis and applications. Our findings suggest that fixed set‐back distances and buffer zones are likely to be inappropriate conservation measures in situations where the numbers of visitors to wildlife areas fluctuates spatially and temporally, as is generally the case. In managing access to wildlife areas there is a need to ensure that larger parties of visitors are kept further away from the nesting areas of vulnerable species or that set‐back distances are determined for the largest party likely to visit the site.
Removing GPS collar bias in habitat selection studies
Authors: Frair Jacqueline L. , Nielsen Scott E. , Merrill Evelyn H. , Lele Subhash R. , Boyce Mark S. , Munro Robin H. M. , Stenhouse Gordon B. , Beyer Hawthorne L. 
Published: April 2004

Summary

Compared to traditional radio‐collars, global positioning system (GPS) collars provide finer spatial resolution and collect locations across a broader range of spatial and temporal conditions. However, data from GPS collars are biased because vegetation and terrain interfere with the satellite signals necessary to acquire a location. Analyses of habitat selection generally proceed without correcting for this known sampling bias. We documented the effects of bias in resource selection functions (RSF) and compared the effectiveness of two bias‐correction techniques.
The effects of environmental conditions on the probability of a GPS collar collecting a location were modelled for three brands of collar using data collected in 24‐h trials at 194 test locations. The best‐supported model was used to create GPS‐biased data from unbiased animal locations. These data were used to assess the effects of bias given data losses in the range of 10–40% at both 1‐ and 6‐h sampling intensities. We compared the sign, value and significance of coefficients derived using biased and unbiased data.
With 6‐h locations we observed type II error rates of 30–40% given as little as a 10% data loss. Biased data also produced coefficients that were significantly more negative than unbiased estimates. Increasing the sampling intensity from 6‐ to 1‐h locations eliminated type II errors but increased the magnitude of coefficient bias. No type I errors or changes in sign were observed.
We applied sample weighting and iterative simulation given a 30% data loss. For a biased vegetation type, simulation reduced more type II errors than weighting, most probably because the original sample size was re‐established. However, selection for areas near trails, which was influenced by a biased vegetation type, showed fewer type II errors after weighting existing animal locations than after simulation. Both techniques corrected 100% and ≥ 80% of the biased coefficients at the 6‐ and 1‐h sampling intensities, respectively.
Synthesis and applications. This study demonstrates that GPS error is predictable and biases the coefficients of resource selection models dependant upon the GPS sampling intensity and the level of data loss. We provide effective alternatives for correcting bias and discuss applying corrections under different sampling designs.
ORIGINAL PAPER. Relative values of the interventions of diversion and improved donor‐arm disinfection to reduce the bacterial risk from blood transfusion
Authors: McDonald C. P. , Roy A. , Mahajan P. , Smith R. , Charlett A. , Barbara J. A. J. 
Published: April 2004

Background and Objectives  The aim of this study was to demonstrate the efficiency of diverting the initial 20‐ml donation from the collection bag and of an improved donor‐arm disinfection procedure in reducing bacterial contamination in blood.Materials and Methods  Donations were collected in bags specially manufactured for the study. These bags incorporated two satellite pouches into each of which 20 ml of blood was collected. Blood initially flowed into sample pouch P1, representing a diversion pouch. Pouch P2 was then filled with 20 ml of blood, which allowed us to sample the collection bag after diversion was complete. Blood then flowed into the standard collection bag. The contents of the pouches were aerobically and anaerobically cultured on the BacT/ALERT automated culture system for 7 days. Two procedures were investigated in the study (each involving 1409 blood donations): one analysed the current disinfection procedure; and the other analysed an improved donor‐arm disinfection procedure.Results  The use of diversion alone resulted in a 47% reduction in contamination, and improved donor‐arm disinfection alone resulted in a 57% reduction in contamination. Diversion plus improved donor‐arm disinfection produced a predicted 77% reduction in contamination.Conclusions  The study validates diversion and an improved donor‐arm disinfection procedure. In combination, these two interventions produced a substantial reduction in contamination. These procedures are to be introduced by the English National Blood Service to enhance the safety of the blood supply.