396 research outputs found
The diet and habitat utilisation of the badger (Meles meles) in an area to the South of Durham city
The study investigates the diet and habitat utilisation of five badger clans in an area of mixed woodland, pasture and arable land between mid May and mid July 1992. During the study period 244 faecal samples were collected and analysed to determine the badgers' diet. Bait marking was used to determine the extent of each clan's home range. Badger diet was then compared with prey availability. The diet consisted predominantly of earthworms. A variety of other invertebrates and cereal were also taken. Earthworms were found to be consumed in greater volume on 'worm nights' than on 'non-worm nights' and this was the only correlation found between availability in the territory and presence in the diet for any of the prey types taken. There was a negative relationship between the percentage frequency of occurrence of cereal and earthworms in the diet. This coupled with the fact that the only badger clan with no cereal available in its territory consumed a significantly greater volume of earthworms than the other clans suggested that there was a relationship between earthworms and cereal in the diet, with badgers replacing one staple food by eating more of another staple food according to availability. The sizes of Coleoptera, larvae and Hymenoptera in the diet were compared with the sizes of these prey items available in the habitat. The results clearly showed that badgers were selecting against the sizes that were commonly available to them. They took significantly more of the larger prey items (˃10mm) than if they were taking them in proportion to their availability in the habitat
Spatial Metrics of Tumour Vascular Organisation Predict Radiation Efficacy in a Computational Model
Intratumoural heterogeneity is known to contribute to poor therapeutic response. Variations in oxygen tension in particular have been correlated with changes in radiation response in vitro and at the clinical scale with overall survival. Heterogeneity at the microscopic scale in tumour blood vessel architecture has been described, and is one source of the underlying variations in oxygen tension. We seek to determine whether histologic scale measures of the erratic distribution of blood vessels within a tumour can be used to predict differing radiation response. Using a two-dimensional hybrid cellular automaton model of tumour growth, we evaluate the effect of vessel distribution on cell survival outcomes of simulated radiation therapy. Using the standard equations for the oxygen enhancement ratio for cell survival probability under differing oxygen tensions, we calculate average radiation effect over a range of different vessel densities and organisations. We go on to quantify the vessel distribution heterogeneity and measure spatial organization using Ripley's L function, a measure designed to detect deviations from complete spatial randomness. We find that under differing regimes of vessel density the correlation coefficient between the measure of spatial organization and radiation effect changes sign. This provides not only a useful way to understand the differences seen in radiation effect for tissues based on vessel architecture, but also an alternate explanation for the vessel normalization hypothesis
Inferring tumour proliferative organisation from phylogenetic tree measures in a computational model
We use a computational modelling approach to explore whether it is possible to infer a solid tumour’s cellular proliferative hierarchy under the assumptions of the cancer stem cell hypothesis and neutral evolution. We focus on inferring the symmetric division probability for cancer stem cells, since this is believed to be a key driver of progression and therapeutic response. Motivated by the advent of multi-region sampling and resulting opportunities to infer tumour evolutionary history, we focus on a suite of statistical measures of the phylogenetic trees resulting from the tumour’s evolution in different regions of parameter space and through time. We find strikingly different patterns in these measures for changing symmetric division probability which hinge on the inclusion of spatial constraints. These results give us a starting point to begin stratifying tumours by this biological parameter and also generate a number of actionable clinical and biological hypotheses including changes during therapy, and through tumour evolution
Assessment of the value of group-based counselling for career construction
This article reports on the change in the career adaptability of participants
exposed to an intervention programme characterized by career and selfconstruction
principles compared to the change in participants who
participated in standard, traditional career counselling lessons. Convenience
and purposive sampling were used to select two groups (experimental
and comparison of Grade 11 learners). Intervention occurred in both
experimental groups. A mixed methods, quasi-experimental, pre-test/posttest
comparison group design was used to gather data. Pre- and post-test
scores obtained on the Career Adapt-Abilities Scale (CAAS) were analysed.
The quantitative results suggested that the intervention programme did not
improve participants’ career adaptability compared to standard, traditional
career counselling lessons as measured by the CAAS. Future research should
include the use of measures of self-reflection and meaning-making to test
the direct effects of experimental interventions.https://www.tandfonline.com/loi/rady20am2019Educational PsychologyStatistic
Inferring tumour proliferative organisation from phylogenetic tree measures in a computational model
We use a computational modelling approach to explore whether it is possible to infer a tumour's cell proliferative hierarchy, under the assumptions of the cancer stem cell hypothesis and neutral evolution. We focus on inferring the symmetric division probability for cancer stem cells in our model, as this is believed to be a key driving parameter of tumour progression and therapeutic response. Given the advent of multi-region sampling, and the opportunities offered by them to understand tumour evolutionary history, we focus on a suite of statistical measures of the phylogenetic trees resulting from the tumour's evolution in different regions of parameter space and through time. We find strikingly different patterns in these measures for changing symmetric division probability which hinge on the inclusion of spatial constraints. These results give us a starting point to begin stratifying tumours by this biological parameter and also generate a number of actionable clinical and biological hypotheses including changes during therapy, and through tumour evolution
Efficacy of outdoor adventure education in developing emotional intelligence during adolescence
This study was an efficacy evaluation of an outdoor adventure intervention to facilitate emotional intelligence (EI) among
adolescents. A pre-post-test design was used. Participants were a convenience sample of 76 Grade 10 learners from a
private high school for boys in a major South African city. They completed the Bar-On EQ-i:YV at pre-intervention,
post-intervention and follow-up. The results indicated that participation in outdoor intervention led to a sustainable increase
in the overall EQ scores of participants as well as in certain subskills of EQ, namley intrapersonal skills, adaptability and
general mood but not in interpersonal skills and stress management.http://www.tandfonline.com/loi/rpia202015-09-30hb201
Constrained Gauge Fields from Spontaneous Lorentz Violation
Spontaneous Lorentz violation realized through a nonlinear vector field
constraint of the type ( is the proposed scale for
Lorentz violation) is shown to generate massless vector Goldstone bosons,
gauging the starting global internal symmetries in arbitrary relativistically
invariant theories. The gauge invariance appears in essence as a necessary
condition for these bosons not to be superfluously restricted in degrees of
freedom, apart from the constraint due to which the true vacuum in a theory is
chosen by the Lorentz violation. In the Abelian symmetry case the only possible
theory proves to be QED with a massless vector Goldstone boson naturally
associated with the photon, while the non-Abelian symmetry case results in a
conventional Yang-Mills theory. These theories, both Abelian and non-Abelian,
look essentially nonlinear and contain particular Lorentz (and ) violating
couplings when expressed in terms of the pure Goldstone vector modes. However,
they do not lead to physical Lorentz violation due to the simultaneously
generated gauge invariance.Comment: 15 pages, minor corrections, version to be published in Nucl. Phys.
Quantum Oscillation Studies of the Fermi Surface of LaFePO
We review recent experimental measurements of the Fermi surface of the
iron-pnictide superconductor LaFePO using quantum oscillation techniques. These
studies show that the Fermi surface topology is close to that predicted by
first principles density functional theory calculations, consisting of
quasi-two-dimensional electron-like and hole-like sheets. The total volume of
the two hole sheets is almost equal to that of the two electron sheets, and the
hole and electron Fermi surface sheets are close to a nesting condition. No
evidence for the predicted three dimensional pocket arising from the Fe
band is found. Measurements of the effective mass suggest a
renormalisation of around two, close to the value for the overall band
renormalisation found in recent angle resolved photoemission measurements.Comment: Submitted to Physica C special issue on iron-pnictide superconductor
Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares
The extreme ultraviolet portion of the solar spectrum contains a wealth of
diagnostic tools for probing the lower solar atmosphere in response to an
injection of energy, particularly during the impulsive phase of solar flares.
These include temperature and density sensitive line ratios, Doppler shifted
emission lines and nonthermal broadening, abundance measurements, differential
emission measure profiles, and continuum temperatures and energetics, among
others. In this paper I shall review some of the advances made in recent years
using these techniques, focusing primarily on studies that have utilized data
from Hinode/EIS and SDO/EVE, while also providing some historical background
and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the
Topical Issue on Solar and Stellar Flare
Genetic relationships within and among Iberian fescues (Festuca L.) based on PCR-amplified markers
The genus Festuca comprises approximately 450 species and is widely distributed around the world. The Iberian Penninsula, with more than 100 taxa colonizing very diverse habitats, is one of its main centers of diversification. This study was conducted to assess molecular genetic variation and genetic relatedness among 91 populations of 31 taxa of Iberian fescues, based on several molecular markers (random amplified polymorphic DNA, amplified fragment length polymorphisms, and trnL sequences). The analyses showed the paraphyletic origin of the broad-leaved (subgenus Festuca, sections Scariosae and Subbulbosae, and subgenus Schedonorus) and the fine-leaved fescues (subgenus Festuca, sections Aulaxyper, Eskia, and Festuca). Schedonorus showed a weak relationship with Lolium rigidum and appeared to be the most recent of the broad-leaved clade. Section Eskia was the most ancient and Festuca the most recent of the fine-leaved clade. Festuca and Aulaxyper were the most related sections, in concordance with their taxonomic affinities. All taxa grouped into their sections, except F. ampla and F. capillifolia (section Festuca), which appeared to be more closely related to Aulaxyper and to a new independent section, respectively. Most populations clustered at the species level, but some subspecies and varieties mixed their populations. This study demonstrated the value in combining different molecular markers to uncover hidden genetic relationships between populations of Festuca
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