bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of initial conditions on two-dimensional free shear layers
Authors: Dziomba B. , Fiedler H. E. 
Published: April 2006

The influence of periodic perturbations on the development of two-dimensional free shear layers generated by a splitter plate was investigated in cases where the ratios of the two velocities u1 and u2 either side of the splitter plate were such that 0 < u1/u2 < 1. Investigations were carried out in both a suction and a blower wind tunnel. Results show that even very weak periodic perturbations caused by the wind tunnel may cause significant nonlinear spreading in the downstream development of the shear layer, a behaviour which is also observed when the shear layer is deliberately excited. Other things being equal, the effect of the disturbance is greater when flow separation at the splitter plate is turbulent than when it is laminar.No self-induced feedback frequencies were measured in the test section. All tonal components that were detected in the flow could be traced to external sources.The influence of trailing-edge thickness on the shear-layer development is found to become significant when it exceeds 50% of the sum of boundary-layer displacement thickness at the point of separation. As the trailing edge becomes thicker, the range over which the shear layer is self-similar is shifted farther downstream. This behaviour may be crucial for predicting the evolution of shear layers in high-speed flows having thin boundary layers at separation.The momentum thickness criterion for estimating the development length of the flow as suggested by Bradshaw is shown to be insufficient for two-stream layers, where additional parameters, e.g. the trailing-edge geometry, have to be taken into account. Discrepancies between previously published observations of shear layers, as well as the considerable scatter in reported measurements, may therefore, to a large extent, be attributable to contamination of the experimental facility.
A numerical study of quasi-geostrophic flow over isolated topography
Authors: Verron J. , Le Provost C. 
Published: April 2006

An extensive set of numerical simulations is performed to synthesize the behaviour of a barotropic flow over isolated topography on an f-plane and on a β-plane. The model is based on the quasi-geostrophic vorticity equation, where the dissipation terms have been retained. The use of open boundary conditions. following the method described by Orlanski (1976), allows detailed simulation of time-dependent flows over long periods.On the f-plane, the ultimate solution is always characterized by a typical vorticity field with an anticyclonic vortex trapped over the topography, but different transient regimes occur, related to the importance of advection versus topography effect: direct advection of the positive vortex for strong flows; eddy interactions and double-vortex-structure appearance for weaker flows; oscillatory regimes with topographic trapped-waves generation for very strong vorticity-interaction cases.On the β-plane, and for prograde flows, the situation is complicated by a Rossby wave pattern extending mainly downstream but also having an upstream component corresponding to zonal waves. For retrograde flows the obstacle does not excite Rossby waves but a transient response with zonal waves whose lifetime depends on the nonlinearity.
Some numerical experiments on developing laminar flow in circular-sectioned bends
Authors: Humphrey J. A. C. , Iacovides H. , Launder B. E. 
Published: April 2006

The paper reports numerical solutions to a semi-elliptic truncation of the Navier–Stokes equations for the case of developing laminar flow in circular-sectioned bends over a range of Dean numbers. The ratios of bend radius to pipe radius are 7:1 and 20:1, corresponding with the configurations examined experimentally by Talbot and his co-workers in recent years. The semi-elliptic treatment facilitates a much finer grid than has been possible in earlier studies. Numerical accuracy has been further improved by assuming radial equilibrium over a thin sublayer immediately adjacent to the wall and by re-formulating the boundary conditions at the pipe centre.Streamwise velocity profiles at Dean numbers of 183 and 565 are in excellent agreement with laser-Doppler measurements by Agrawal, Talbot & Gong (1978). Good, albeit less complete, accord is found with the secondary velocities, though the differences that exist may be mainly due to the difficulty of making these measurements. The paper provides new information on the behaviour of the streamwise shear stress around the inner line of symmetry. Upstream of the point of minimum shear stress, our numerical predictions display a progressive shift towards the result of Stewartson, Cebici & Chang (1980) as the Dean number is successively raised. Downstream of the minimum, however, in contrast with the monotonic approach to an asymptotic level reported by Stewartson, the numerical solutions display a damped oscillatory behaviour reminiscent of those from Hawthorne's (1951) inviscid-flow calculations. The amplitude of the oscillation grows as the Dean number is raised.
Occurrence of the Cys611Tyr mutation and a novel Arg886Trp substitution in the RET proto‐oncogene in multiple endocrine neoplasia type 2 families and sporadic medullary thyroid carcinoma cases originating from the central region of Portugal
Authors: Prazeres Hugo João , Rodrigues Fernando , Figueiredo Paulo , Naidenov Plamen , Soares Paula , Bugalho Maria João , Lacerda Manuela , Campos Beatriz , Martins Teresa C. 
Published: April 2006

SummaryObjective  Medullary thyroid carcinoma (MTC) occurs both sporadically and in the context of autosomal dominantly inherited multiple endocrine neoplasia type 2 (MEN2) syndromes: MEN2A, MEN2B, and familial medullary thyroid carcinoma (FMTC), which are caused by activating germline mutations in the RET proto‐oncogene. The aim of this study was to characterize the RET mutational spectrum in MEN2 families and apparently sporadic MTC (AS‐MTC) cases originating from the central region of Portugal.Subjects and methods  We studied a total of 82 individuals (64 affected and 18 family members), comprising five MEN2 families (four MEN2A and one MEN2B), as well as 53 AS‐MTC cases. RET germline mutations were screened using PCR‐DNA sequencing, SSCP and RFLP. The haplotypes associated with recurrent mutations were determined by fragment analysis of microsatellite markers, and by RFLP, in the case of intragenic polymorphisms.Results  Frequency of the Cys611Tyr (TGC‐TAC) mutation was significantly increased in this region of Portugal, due to the fact that three apparently unrelated MEN2A/FMTC families, out of the five in which mutations were identified, harboured this specific mutation. Haplotype analysis revealed that a common haplotype was shared between two of these three families. We have also characterized a novel RET mutation, Arg886Trp, located in the tyrosine kinase domain, which was found in an AS‐MTC case.Conclusions  There are regional specificities in the relative frequency of RET mutations, which are consistent with a cluster‐like distribution of specific disease‐causing mutations, as a result of the inheritance of a shared haplotype. These data, along with the finding of a novel RET mutation (Arg886Trp), have important implications towards facilitating and improving the molecular diagnosis of hereditary MTC on a regional basis.
Starve and survive: stress tolerance and life‐history traits of a bdelloid rotifer
Authors: RICCI C. , PERLETTI F. 
Published: April 2006

Summary

Bdelloid rotifers occur in unstable habitats, such as moss, lichens and temporary pools, where conditions change unpredictably and dramatically. Their ability to survive in such habitats could be related to their physiological ability to enter metabolic stasis in response to severe environmental stress. We tested the response of a bdelloid species (Macrotrachela quadricornifera Milne, 1886) to prolonged starvation by evaluating survival and fecundity once food was resupplied on a regular basis.
Animals were starved for different durations (20, 40, 60 days) and all survivors resumed reproduction. Life‐history parameters of the 20‐day starvation group subsequent to the resumption of normal feeding were studied.
From resumption of normal feeding, mean longevity and age‐specific traits of starved rotifers were the same as those of the fed rotifers. No reduction of lifetime fecundity was found in the bdelloids that experienced starvation, suggesting a time shift of the effective ‘age’ of the starved rotifers.
The response of the rotifer to starvation is similar to that induced by drought. The presence of a previously undocumented form of dormancy is hypothesized.
Growth–survival trade‐offs and allometries in rosette‐forming perennials
Authors: METCALF C. J. E. , REES M. , ALEXANDER J. M. , ROSE K. 
Published: April 2006

Summary

Demographic rates such as growth and survival may interact directly as a result of allocation constraints, or indirectly through their relationship with structural characteristics.
We explored the relationship between growth and survival in a range of rosette‐forming species across different habitats, and investigated possible mechanistic explanations for the patterns we found.
Results indicated a negative association between growth and survival in small plants across species in different habitats. There was no relationship for large plants.
Relative growth rate (RGR) was positively correlated to specific leaf area (SLA), but unrelated to the percentage biomass allocated to roots. This argues against the hypothesized role of allocation to root mass in mediating the growth–survival trade‐off.
The pattern of biomass partitioning was compared with the predictions of Enquist & Niklas (2002a) Global allocation rules for patterns of biomass partitioning in seed plants. Science 295, 1517–1520. In agreement with their predictions, the overall relationship between above‐ and below‐ground biomass was isometric. However, after accounting for species‐specific effects it was found that allocation to roots varied widely between species and was size‐dependent, suggesting that the conventional statistical analysis (double‐log regression) may be insensitive to biologically important sources of variation.
Do bumble bees save time when choosing novel flowers by following conspecifics?
Authors: KAWAGUCHI L. G. , OHASHI K. , TOQUENAGA Y. 
Published: April 2006

Summary

Spatio‐temporal variation in resource availability is often large and unpredictable. When animals need to find and sample novel foods, therefore they may prefer to choose food sources with feeding conspecifics or odour left by the conspecifics. This behaviour (local enhancement) would be favoured, especially if it decreases the time spent on food‐finding and subsequent decision‐making. In laboratory experiments we tested if naive bumble bees use local enhancement, and to what degree it could reduce the time spent on finding and sampling novel flowers.
When naive bees were presented with a pair of equally rewarded artificial or real flowers in a flight cage, they preferred to land and feed on the flower where a dead conspecific was attached. The presence of conspecifics reduced the time spent on detecting floral reward, which was significant only when bees chose between real flowers. In a similar pairwise choice, bees landed on artificial flowers with a dead conspecific wrapped in plastic more frequently than on flowers with the same‐sized plastic wrap including no bees, which suggests that visual cues have important influences on the bees’ flower choice.
Effects of conspecifics on flower choice and food detection time were most evident when they were attached to real flowers, and least evident when they were wrapped in plastic. These results suggest that the presence of conspecifics on flowers has stronger effects on bees’ decision‐making as the attractiveness of flowers increases, and that bees use both visual and non‐visual cues to recognize conspecifics on flowers.
If the benefit of saving time were universal, the use of local enhancement would also be advantageous when bees switch between focal flower species or sites in response to temporal changes in resource availability.
Phytohemagglutinin‐induced skin swelling in birds: histological support for a classic immunoecological technique
Authors: MARTIN L. B. , HAN P. , LEWITTES J. , KUHLMAN J. R. , KLASING K. C. , WIKELSKI M. 
Published: April 2006

SummaryMeasurements of phytohemagglutinin (PHA)‐induced tissue swelling are arguably the most popular surrogates for immunocompetence in wild birds. It is largely unresolved, however, whether the basic assumption underlying these measures is valid, particularly whether more swelling represents a ‘better’ or ‘stronger’ cell‐mediated immune response.In this study we took a first step towards such validation by characterizing immune cell infiltration over time into the wing‐webs (patagia) of PHA‐challenged House Sparrows (Passer domesticus). Relative to saline‐injected wing‐webs, PHA‐injected wing‐webs displayed intensive infiltration of many immune cell types, including basophils, eosinophils, heterophils, lymphocytes, macrophages and thrombocytes. The abundance of most of these cell types changed over the course of the swelling response (6–48 h post‐injection). Peak infiltration time varied depending on cell type. At several time points, significant correlations between the numbers of some cell types (particularly heterophils) and the degree of swelling were detected.Together, these data indicate that PHA‐induced swelling is related to heightened immune cell activity in House Sparrows, but also that the PHA swelling response in this species is dynamic and involves both innate and adaptive components of the immune system. We thus caution against interpreting larger swellings as ‘greater cell‐mediated immunocompetence’, given the complex nature of this immune response.
Inter‐ and intraspecific differences in climatically mediated phenological change in coexistingTriturusspecies
Authors: CHADWICK ELIZABETH A. , SLATER FREDERICK M. , ORMEROD S. J. 
Published: April 2006

AbstractClimate and weather affect phenological events in a wide range of taxa, and future changes might disrupt ecological interactions. Amphibians are particularly sensitive to climate, but few studies have addressed climatically mediated change in the phenology of closely related species or sexes. Here, we test the hypothesis that changes in spring temperatures result in phenological change amongTriturus, and we examine inter‐ and intraspecific differences in response. Coexisting populations ofTriturus helveticusandTriturus vulgarisat Llysdinam pond in mid‐Wales (53°12′59″N 3°27′3″W) were monitored using pitfall traps along a drift fence during 1981–1987, and again in 1997–2005. Spring temperature over the same period explained up to 74% of between‐year variability in median arrival date, with a significant advance of 2–5 days with every degree centigrade increase. Changes were greater for males than females of both species, and greater forT. helveticusthanT. vulgariswithin sexes, resulting in an increasing temporal separation between arrivals of maleT. helveticusand all other groups. These data illustrate for the first time how climatic change might have differential effects on sympatric species and on the two sexes.
Different patterns of inflammation and prognosis in invasive carcinoma of the breast
Authors: Lee A H S , Gillett C E , Ryder K , Fentiman I S , Miles D W , Millis R R 
Published: April 2006

Aim : Inflammation in carcinoma of the breast may represent an immune response to the tumour, but there is evidence that this response is impaired. Inflammation may also stimulate tumour growth by releasing proteolytic enzymes and angiogenic factors. Prognostic studies have produced conflicting results, but most investigators have not evaluated the different patterns of inflammation. The aim of this study was to test the hypothesis that moderate or marked diffuse inflammation is associated with a better prognosis. We also tested the ‘danger model’, which suggests that necrosis is necessary for an effective immune response.Methods and results : On multivariate analysis of women with stage 1 and 2 tumours (n = 679, median follow‐up of 9.8 years), survival was independently associated with diffuse inflammation (relative risk 0.43, 95% confidence interval 0.24, 0.77, P =0.005) in addition to histological grade, axillary lymph node status, tumour size and oestrogen receptor status. The presence or absence of tumour necrosis did not have a clear effect on the relationship between survival and diffuse inflammation.Conclusions : Moderate or marked diffuse inflammation in breast cancer is associated with a better prognosis, suggesting that the immune effects of the inflammation predominate over the protumour effects.
Behaviourally mediated indirect effects: interference competition increases predation mortality in foraging redshanks
Authors: MINDERMAN JEROEN , LIND JOHAN , CRESSWELL WILL 
Published: April 2006

Summary

The effect of competition for a limiting resource on the population dynamics of competitors is usually assumed to operate directly through starvation, yet may also affect survival indirectly through behaviourally mediated effects that affect risk of predation. Thus, competition can affect more than two trophic levels, and we aim here to provide an example of this.
We show that the foraging success of redshanks Tringa totanus (L.) foraging on active prey was highest in the front of flocks, whereas this was not the case for redshanks foraging on inactive prey. Also, when foraging on active prey, foraging success in a flock decreased as more birds passed through a patch, while overall foraging success was not lower on subsequent visits to the same patch. Thus, redshanks foraging on active prey suffered from interference competition, whereas this was not the case for redshanks foraging on inactive prey.
This interference competition led to differences in activity: redshanks attaining a lower foraging success had a higher walking rate. Greater activity was associated with wider flock spacing and shorter distances to cover, which has previously been shown to increase predation risk and mortality from sparrowhawks Accipiter nisus (L.).
We conclude that behavioural adaptations of prey species can lead to interference competition in foraging redshanks, and thus can affect their predation risk and mortality through increased activity. This study is one of the first to show how interference competition can be a mechanism for behaviourally mediated indirect effects, and provides further evidence for the suggestion that a single species occupying an intermediate trophic level may be simultaneously top‐down controlled by a predator and bottom‐up controlled by a behavioural response of its prey.
Critical aneurysmal dilatation of the thoracic aorta in young adolescents with variant hyperimmunoglobulin E syndrome
Authors: VAN DER MEER J. W. M. , WEEMAES C. M. R. , VAN KRIEKEN J. H. , BLOMJOUS C. E. M. , VAN DIE C. E. , NETEA M. G. , BREDIE S. J. H. 
Published: April 2006

Abstract.The autosomal‐dominant (AD) form of the hyperimmunoglobulin E syndrome (HIES) has been described as a multisystem disorder including immune, skeletal and dental abnormalities. Recently, the evaluation of patients from families in which HIES was inherited in a manner more consistent with autosomal‐recessive (AR) inheritance, showed that AR‐HIES is a clinically distinct disease entity. In addition to classical immunologic findings of AD‐HIES, the AR form presents with severe recurrent fungal and viral infections with herpes zoster, herpes simplex and characteristic mollusca contagiosa. Furthermore, cerebral vascular sequelae, including vasculitis, infarction and haemorrhage were noted. In this report, we describe the clinical picture of two patients who showed remarkable resemblance to the description of AR‐HIES, but also developed fatal aneurysmal dilatation of the thoracic aorta in adolescence. This finding may further consummate the clinical picture of AR‐HIES and emphasize the possibility to develop early aortitis, most likely preceding the critical aneurysm formation at older age. This process should be anticipated during childhood in cases with AR‐HIES.
Scurvy: a disease almost forgotten
Authors: Olmedo Jesse M. , Yiannias James A. , Windgassen Elizabeth B. , Gornet Michael K. 
Published: April 2006

AbstractBackground  Although much decreased in prevalence, scurvy still exists in industrialized societies. Few recent large studies have examined its pathogenesis, signs, and symptoms.Methods  After we diagnosed scurvy in a 77‐year‐old female patient in 2003, we conducted a retrospective records review to identify patients with scurvy treated between 1976 and 2002 at Mayo Clinic (Scottsdale, Arizona; Rochester, Minnesota; or Jacksonville, Florida). We also searched the English‐language medical literature for published reports on scurvy.Results  In addition to our patient, seven of 11 patients whose records in the institutional database mentioned vitamin C deficiency were women. The age ranged from a neonate to 77 years (mean, 48 years). The most common associated causes were concomitant gastrointestinal disease, poor dentition, food faddism, and alcoholism. Vitamin or mineral deficiencies other than vitamin C deficiency were also found in our patients who had scurvy. The most common symptoms were bruising, arthralgias, or joint swelling. The most common signs were pedal edema, bruising, or mucosal changes. Four patients had vague symptoms of myalgias and fatigue without classic findings, and five had concomitant nutritional deficiencies. Follow‐up available for six of 12 patients treated by vitamin C supplementation showed complete resolution of symptoms in five.Conclusions  Patients with scurvy may present with classic symptoms and signs or with nonspecific clinical symptoms and an absence of diagnostically suggestive physical findings. Concomitant deficiency states occur not uncommonly. Taking a thorough dietary history and measuring serum ascorbic acid levels should be considered for patients with classic signs and symptoms, nonspecific musculoskeletal complaints, or other vitamin or mineral deficiencies.
The ethics of xenotransplantation: a survey of student attitudes
Authors: Pearce C. E. , Thomas A. P. M. , Clements D. A. V. 
Published: April 2006

Pearce CE, Thomas APM, Clements DAV. The ethics of xenotransplantation: a survey of student attitudes. Xenotransplantation 2006; 13: 253–257. © Blackwell Munksgaard, 2006Abstract:  Xenotransplantation is a burgeoning technology that could provide a solution to the shortage of organs and tissue for transplantation. It does, however, raise many moral and ethical dilemmas. The aim of this study was to evaluate undergraduate university students' knowledge and opinions on the controversial practice. Choice of science or arts subjects and gender were also assessed to establish if they were influencing factors. A total of 100 students, 50 science students and 50 arts students, answered a questionnaire. Seventy‐seven percent of the students had heard of xenotransplantation, 66% believed it would be beneficial to society and only 45% believed it to be ethically and morally acceptable. The medical need for organs was highlighted as the most important argument in favour, and the risk of infection was revealed to be the most important argument against xenotransplantation. The students would significantly prefer a human to non‐human animal organ, and did not believe the genetic modification of animals for transplantation was ethically acceptable. This study, in general, did not find that knowledge and acceptance of xenotransplantation was associated with subject background (i.e., science or arts courses) or gender.