1,564 research outputs found
The effect of patient positioning on the duration of venous reflux in Duplex ultrasound for venous insufficiency
Radiolabelling of Corynebacterium parvum and its distribution in mice.
Corynebacterium parvum was labelled by growing live bacteria in the presence of [3H]thymidine. The bacteria were killed by formalin, washed thoroughly and resuspended at a concentration of 7 mg dry weight/ml. An activity of 1-6 X 10(5) ct/min/0-1 ml was obtained. The biological properties (inhibition of tumour growth and hepatosplenomegaly) of the labelled C. parvum were compared with those of commercially available vaccine, and were found to be similar. Labelled C. parvum was injected i.v., i.p., or s.c. into normal C57BL mice and the localization of activity determined at 4 h and 1,3,7 and 14 days after injection. After i.v. or i.p. injection, highest counts were recorded in the liver. Moderate activity was found in the spleen, lungs and small gut. After s.c. injection, the majority of radioactive label was detected at the site of injection and little found in other tissues. The distribution of injected C. parvum was also studied in mice bearing Lewis tumour, and was found to be similar to that in normal mice. Moderate amounts of labelled C. parvum were recovered from tumour. There appeared to be no relationship between the antitumour effect of C. parvum given by a particular route of injection and the concentration of C. parvum recovered from the tumour
Repeatability of plantar pressure assessment during barefoot walking in people with stroke
Stroke-related changes in foot structure and function affect balance and mobility and quantifying foot function following stroke could offer clinically useful information to inform rehabilitation. The aim of this work was to explore the feasibility of undertaking plantar pressure assessment during barefoot walking in people with stroke, and evaluate the repeatability of the assessment protocol and regional footprint analysis as a measure of dynamic foot characteristics
Overground endoscopic findings and respiratory sound analysis in horses with recurrent laryngeal neuropathy after unilateral laser ventriculocordectomy
Background:
Unilateral ventriculocordectomy (VeC) is frequently performed, yet objective studies in horses with naturally occurring recurrent laryngeal neuropathy (RLN) are few.
Objectives:
To evaluate respiratory noise and exercising overground endoscopy in horses with grade B and C laryngeal function, before and after unilateral laser VeC.
Study design:
Prospective study in clinically affected clientāowned horses.
Methods:
Exercising endoscopy was performed and concurrent respiratory noise was recorded. A leftāsided laser VeC was performed under standing sedation. Owners were asked to present the horse for reāexamination 6ā8 weeks postāoperatively when exercising endoscopy and sound recordings were repeated. Exercising endoscopic findings were recorded, including the degree of arytenoid stability. Quantitative measurement of leftātoāright quotient angle ratio (LRQ) and rima glottidis area ratio (RGA) were performed preā and postāoperatively. Sound analysis was performed, and measurements of the energy change in F1, F2 and F3 formants between preā and postāoperative recordings were made and statistically analysed.
Results:
Three grade B and seven grade C horses were included; 6/7grade C horses preoperatively had bilateral vocal fold collapse (VFC) and 5/7 had mild rightāsided medial deviation of the aryāepiglottic fold (MDAF). Right VFC and MDAF was still present in these horses postāoperatively; grade B horses had no other endoscopic dynamic abnormalities postāoperatively. Sound analysis showed significant reduction in energy in formant F2 (P = 0.05) after surgery.
Main limitations:
The study sample size was small and multiple dynamic abnormalities made sound analysis challenging.
Conclusions:
RLNāaffected horses have reduction in sound levels in F2 after unilateral laser VeC. Continuing noise may be caused by other ongoing forms of dynamic obstruction in grade C horses. Unilateral VeC is useful for grade B horses based on endoscopic images. In grade C horses, bilateral VeC, right aryāepiglottic fold resection Ā± laryngoplasty might be a better option than unilateral VeC alone
Population change in breeding boreal waterbirds in a 25-year perspective : What characterises winners and losers?
Understanding drivers of variation and trends in biodiversity change is a general scientific challenge, but also crucial for conservation and management. Previous research shows that patterns of increase and decrease are not always consistent at different spatial scales, calling for approaches combining the latter. We here explore the idea that functional traits of species may help explaining divergent population trends. Complementing a previous community level study, we here analyse data about breeding waterbirds on 58 wetlands in boreal Fennoscandia, covering gradients in latitude as well as trophic status. We used linear mixed models to address how change in local abundance over 25 years in 25 waterbird species are associated with life history traits, diet, distribution, breeding phenology, and habitat affinity. Mean abundance increased in 10 species from 1990/1991 to 2016, whereas it decreased in 15 species. Local population increases were associated with species that are early breeders and have small clutches, an affinity for luxurious wetlands, an herbivorous diet, and a wide breeding range rather than a southern distribution. Local decreases, by contrast, were associated with species having large clutches and invertivorous diet, as well as being late breeders and less confined to luxurious wetlands. The three species occurring on the highest number of wetlands all decreased in mean abundance. The fact that early breeders have done better than late fits well with previous research about adaptability to climate change, that is, response to earlier springs. We found only limited support for the idea that life history traits are good predictors of wetland level population change. Instead, diet turned out to be a strong candidate for an important driver of population change, as supported by a general decrease of invertivores and a concomitant increase of large herbivores. In a wider perspective, future research needs to address whether population growth of large-bodied aquatic herbivores affects abundance of co-occurring invertivorous species, and if so, if this is due to habitat alteration, or to interference or exploitative competition.Peer reviewe
The roles of migratory and resident birds in local avian influenza infection dynamics
Migratory birds are an increasing focus of interest when it comes to infection dynamics and the spread of avian influenza viruses (AIV ). However, we lack detailed understanding of migratory birdsā contribution to local AIV prevalence levels and their downstream socioāeconomic costs and threats.
To explain the potential differential roles of migratory and resident birds in local AIV infection dynamics, we used a susceptibleāinfectiousārecovered (SIR ) model. We investigated five (mutually nonā exclusive) mechanisms potentially driving observed prevalence patterns: (1) a pronounced birth pulse (e.g. the synchronised annual influx of immunologically naĆÆve individuals), (2) shortāterm immunity, (3) increase in susceptible migrants, (4) differential susceptibility to infection (i.e. transmission rate) for migrants and residents, and (5) replacement of migrants during peak migration.
SIR models describing all possible combinations of the five mechanisms were fitted to individual AIV infection data from a detailed longitudinal surveillance study in the partially migratory mallard duck (Anas platyrhynchos ). During autumn and winter, the local resident mallard community also held migratory mallards that exhibited distinct AIV infection dynamics.
Replacement of migratory birds during peak migration in autumn was found to be the most important mechanism driving the variation in local AIV infection patterns. This suggests that a constant influx of migratory birds, likely immunological naĆÆve to locally circulating AIV strains, is required to predict the observed temporal prevalence patterns and the distinct differences in prevalence between residents and migrants.
Synthesis and applications . Our analysis reveals a key mechanism that could explain the amplifying role of migratory birds in local avian influenza virus infection dynamics; the constant flow and replacement of migratory birds during peak migration. Apart from monitoring efforts, in order to achieve adequate disease management and control in wildlifeāwith knockāon effects for livestock and humans,āwe conclude that it is crucial, in future surveillance studies, to record host demographical parameters such as population density, timing of birth and turnover of migrants
Non-diagonal open spin-1/2 XXZ quantum chains by separation of variables: Complete spectrum and matrix elements of some quasi-local operators
The integrable quantum models, associated to the transfer matrices of the
6-vertex reflection algebra for spin 1/2 representations, are studied in this
paper. In the framework of Sklyanin's quantum separation of variables (SOV), we
provide the complete characterization of the eigenvalues and eigenstates of the
transfer matrix and the proof of the simplicity of the transfer matrix
spectrum. Moreover, we use these integrable quantum models as further key
examples for which to develop a method in the SOV framework to compute matrix
elements of local operators. This method has been introduced first in [1] and
then used also in [2], it is based on the resolution of the quantum inverse
problem (i.e. the reconstruction of all local operators in terms of the quantum
separate variables) plus the computation of the action of separate covectors on
separate vectors. In particular, for these integrable quantum models, which in
the homogeneous limit reproduce the open spin-1/2 XXZ quantum chains with
non-diagonal boundary conditions, we have obtained the SOV-reconstructions for
a class of quasi-local operators and determinant formulae for the
covector-vector actions. As consequence of these findings we provide one
determinant formulae for the matrix elements of this class of reconstructed
quasi-local operators on transfer matrix eigenstates.Comment: 40 pages. Minor modifications in the text and some notations and some
more reference adde
āO sibling, where art thou?ā ā a review of avian sibling recognition with respect to the mammalian literature
Avian literature on sibling recognition is rare compared to that developed by mammalian researchers. We compare avian and mammalian research on sibling recognition to identify why avian work is rare, how approaches differ and what avian and mammalian researchers can learn from each other. Three factors: (1) biological differences between birds and mammals, (2) conceptual biases and (3) practical constraints, appear to influence our current understanding. Avian research focuses on colonial species because sibling recognition is considered adaptive where āmixing potentialā of dependent young is high; research on a wider range of species, breeding systems and ecological conditions is now needed. Studies of acoustic recognition cues dominate avian literature; other types of cues (e.g. visual, olfactory) deserve further attention. The effect of gender on avian sibling recognition has yet to be investigated; mammalian work shows that gender can have important influences. Most importantly, many researchers assume that birds recognise siblings through ādirect familiarisationā (commonly known as associative learning or familiarity); future experiments should also incorporate tests for āindirect familiarisationā (commonly known as phenotype matching). If direct familiarisation proves crucial, avian research should investigate how periods of separation influence sibling discrimination. Mammalian researchers typically interpret sibling recognition in broad functional terms (nepotism, optimal outbreeding); some avian researchers more successfully identify specific and testable adaptive explanations, with greater relevance to natural contexts. We end by reporting exciting discoveries from recent studies of avian sibling recognition that inspire further interest in this topic
Patterns of predator behaviour and wood warbler Phylloscopus sibilatrix nest survival in a primaeval forest
Understanding the foraging behaviour of predators is key to interpreting the role of anti-predator adaptations of birds in reducing nest losses. Conducting research in primeval habitats, with low direct human interference, is particularly valuable in the understanding of predator-prey interactions. Using nest cameras, we investigated the identity and behaviour of potential and actual predators appearing at Wood Warbler Phylloscopus sibilatrix nests, and the importance of different predator groups for nest survival, in the primeval part of BiaÅowieża Forest (Poland). Mammals formed the main predator group (30 of 32 nest depredations), particularly medium-sized carnivores (24 of 32), which attacked nests more frequently than merely passing by. This contrasted with other species, especially small rodents that were commonly recorded near nests but rarely attacked them. Most nest attacks (22 of 32) took place at night and nest survival did not depend on nest visibility, indicating a reduced utility of nest concealment in defence against predators using mainly sound or olfaction when hunting. Daily nest survival declined strongly with nest progression (from egg-laying to fledging of chicks), likely due to increased predator detection of nests containing older and louder chicks, and not due to increasing parental activity at nests during the day. The set of actual nest predators differed from some previous studies in human-transformed habitats, showing that Wood Warblers may face differing threats in modified versus near-pristine environments
Climate adaptation and speciation : particular focus on reproductive barriers in Ficedula flycatchers
Climate adaptation is surprisingly rarely reported as a cause for the build-up of reproductive isolation between diverging populations. In this review, we summarize evidence for effects of climate adaptation on pre- and postzygotic isolation between emerging species with a particular focus on pied (Ficedula hypoleuca) and collared (Ficedula albicollis) flycatchers as a model for research on speciation. Effects of climate adaptation on prezygotic isolation or extrinsic selection against hybrids have been documented in several taxa, but the combined action of climate adaptation and sexual selection is particularly well explored in Ficedula flycatchers. There is a general lack of evidence for divergent climate adaptation causing intrinsic postzygotic isolation. However, we argue that the profound effects of divergence in climate adaptation on the whole biochemical machinery of organisms and hence many underlying genes should increase the likelihood of genetic incompatibilities arising as side effects. Fast temperature-dependent co-evolution between mitochondrial and nuclear genomes may be particularly likely to lead to hybrid sterility. Thus, how climate adaptation relates to reproductive isolation is best explored in relation to fast-evolving barriers to gene flow, while more research on later stages of divergence is needed to achieve a complete understanding of climate-driven speciation.Peer reviewe
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