3,006 research outputs found
New Eastern Record of \u3ci\u3ePtosima Walshii\u3c/i\u3e (Coleoptera: Buprestidae)
Ptosima walshii LeConte (Coleoptera: Buprestidae) is reported for the first time in Pennsylvania, being the eastern-most record of the species. Four specimens were captured in Lindgren funnel traps in Bedford and Fulton counties during invasive wood-destroying beetle surveys
Performance of microstructural finite element models in predicting the effective modulus of trabecular bone
Trabecular bone is made up of an irregular, interconnecting framework of rod- and plate-like struts [1], therefore the mechanical properties of the bone may only be determined through experimental testing or detailed Finite Element modelling. Experimental testing requires a sample to be removed from the body, which is not possible in living patients. As such, there is a drive to move away from experimental testing and focus instead on creating accurate patient-specific Finite Element models from CT scans of the bone. The computational āgold-standardā Finite Element model used for trabecular bone, namely the voxel-based method, uses solid tetrahedral elements, which are extremely resource intensive. Vanderoost, et al [2] developed an alternative Finite Element code which discretises the structure into a series of beams and shells. This beam-shell approach vastly reduces the size of the mesh and, consequently, the processing time required for the simulation. In this work, an analysis cycle was developed to determine the apparent modulus of a structure using the beam-shell Finite Element model [2]. The cycle imports micro-CT scans of a structure, discretises the structure into a beam-shell mesh, performs a Finite Element simulation and outputs the apparent modulus of the structure along with a reconstructed image. The analysis cycle was validated by analysing over 3000 artificially generated images, comprising various configurations of cubic lattices, Kelvin cell lattices and octet truss lattices, and comparing the modulus output by the analysis cycle to baseline results obtained through the simulation of known node and element data. The analysis cycle provided predictions within 10% of the baseline value for most lattices, however there were issues associated with the rasterisation of the input images and postprocessing which caused variation in the results. Overall, it was determined that the analysis cycle is capable of capturing the apparent modulus of a variety of different structures. Micro-CT scans of 127 bone specimens were run through the analysis cycle. The results from the beam-shell analysis were compared to results from experimental testing [3] and an equivalent voxel-based analysis. There was a clear trend in both the beam-shell and voxel-based data, however the voxel-based method produced stiffer results than the beam-shell method overall. The beam-shell method showed more scatter than the voxel-based method, but contained less significant outliers. The effective modulus, i.e. the modulus of an inner core region, was determined for 17 of the bone specimens and compared to equivalent experimental results. The beam-shell method captured the increase in stiffness between the apparent modulus and the effective modulus as regularly as the voxel-based method, given appropriate boundary conditions were applied. The results produced by both methods can be improved by the removal of machining artifacts and improved segmentation of the micro-CT scans. This work confirms that the beam-shell method is capable of capturing the apparent modulus of a trabecular bone sample, however the scatter in the data must be reduced for it to be considered a viable alternative to the voxel-based method. It was found that the beamshell method is equally capable of predicting the relationship between apparent modulus and effective modulus as the voxel-based method. In both the beam-shell results and voxel-based results, the accuracy of a particular data point could only be determined by considering the results in reference to additional simulation and experimental data points. In light of these results, researchers should be cautious in reporting simulation results for trabecular bone without additional verification
Potential platinum DNA-Metallointercalators : synthesis, characterisation and 1H NMR studies on [Pt(diimine)(N,N-di(n-butyl)-N'-acylthioureato)]+PF6 complexes in solution
Summary in English.Includes bibliographical references.A series of mixed-ligand [Pt(diimine)(N,N-di(n-butyl)-N'-acylthioureato)fPF6- complexes has been synthesised and fully characterised (where diimine is: 1,10 phenanthroline; 4,7-diphenyl-1,10- phenanthroline; 2,2'-bipyridyl; 4,4'-dimethyl-2,2'-bipyridyl and 4,4'-di-tert-butyl-2,2'-bipyridyl and acyl is: benzoyl or naphthoyl)
The use of novel tumour markers and statistical models in the preoperative diagnosis of ovarian cancer
Malignant ovarian tumours are diagnosed at an advanced stage in 75% of
cases and they have the highest mortality figures of all gynaecological
cancers. As the treatment of benign and malignant adnexal masses is
significantly different it is important to be able to reliably distinguish
between them preoperatively. Thus, women with malignancies could be
referred to cancer centres, whilst those with benign conditions could be
offered more conservative management.The aims of this thesis are (1) To investigate the use of new tumour markers
in the preoperative diagnosis of ovarian cancer. (2) To validate previously
published models and compare their performance to subjective assessment
and to the models developed in this thesis. (3) To investigate the differences
between small asymptomatic masses and large masses and to investigate the
accuracy of published models on the diagnosis of malignancy in small
masses.CA 125, CA 15-3 and CA 72-4 were significantly raised in the presence of
ovarian cancer. CA 72-4 was higher in mucinous cancers and CA 125 and CA
15-3 were higher in serous and endometrioid cancers. Her-2/neu and CA 19-9
were not significantly different in benign or malignant disease. Logistic
regression analysis showed age, CA125 and CA 15-3 to be the most valuable
discriminators. A neural network was designed and trained which gave a
sensitivity of 100% and a specificity of 90.9% on the test set. None of the six
published models tested prospectively performed as well as in their original
publication. The IOTA logistic regression model performed best and gave a
sensitivity of 81.8% and a specificity of 72.3%. Subjective assessment of the
mass gave a sensitivity of 72.7% with a specificity of 81.8%. Small masses
were more commonly unilocular and large masses multilocular. Ascites,
papillary proliferations, detectable flow and the smoothness of the internal
wall discriminated well between benign and malignant small cysts. Age,
menopausal status and CA125 were not discriminatory. None of the
published models were as accurate as subjective assessment at diagnosing
malignancy. These data suggest that statistical models may be of less value
than tumour markers and subjective assessment in the diagnosis of ovarian
malignancy.This work improves our ability to predict malignancy in a pelvic mass. As a
result of this work, further research might aim to combine the use of tumour
markers and subjective assessment to improve the preoperative diagnosis of
malignancy. It may thus be possible to provide care in a cancer centre for
those women that need it and to allow conservative management or
minimally invasive surgery for women with benign disease
Pseudoeffective and nef classes on abelian varieties
The cones of divisors and curves defined by various positivity conditions on
a smooth projective variety have been the subject of a great deal of work in
algebraic geometry, and by now they are quite well understood. However the
analogous cones for cycles of higher codimension and dimension have started to
come into focus only recently. The purpose of this paper is to explore some of
the phenomena that can occur by working out the picture fairly completely in a
couple of simple but non-trivial cases. Specifically, we study cycles of
arbitrary codimension on the self-product of an elliptic curve with complex
multiplication, as well as two dimensional cycles on the product of a very
general abelian surface with itself. Already one finds various non-classical
behavior, for instance nef cycles that fail to be pseudoeffective: this answers
a question raised in 1964 by Grothendieck in correspondence with Mumford. We
also propose a substantial number of open problems for further investigation
Exploring social network dynamics driving knowledge management for innovation
The competitiveness and sustainability of a modern organization depends on its ability to innovate successfully. It is accepted (Gratton, 2000; Iles, 1996) that knowledge, skills and competencies are the key drivers of innovation. Innovation is the combined activity of generating new knowledge and the subsequent successful exploitation of this for benefit (von Stamm, 2003; OāSullivan and Dooley, 2008). A key contribution to our understanding of how knowledge produces innovations is that innovation rarely involves a single technology or market but rather a bundle of knowledge which is brought together into a configuration. It is about accessing and using knowledge about components but also about their integration (Tidd et al., 2005). Consequently, current perspectives of the innovation process view it as an interactive and networked system that spans organizational boundaries to draw on knowledge, experience and capabilities from diverse sources (Rothwell, 1992; Tidd et al, 2005). The result is that the locus of innovation and knowledge circulation lies in dynamic, competency-based, business networks (Voss, 2003; Walters, and Buchanan, 2001; Wright, and Burns, 1998)
Altruistic and Warm-Glow Motivations: Differentiating First Time From Repeat Donors
The conversion rate of 1st time donors to their 2nd and 3rd donation is low creating a significant problem to transfusion services. We hypothesise that feelings of warm-glow associated with donating blood, contribute to the differentiation between 1st time donors from those making 2nd or 3rd donations. To test this free-response motivations were examined a sample of 309 blood donors, categorised as 1st time donors and two categories of repeat donor: (1) those making their 2nd or 3rd donation and (2) those making their 4th or subsequent donation. We identified 33 categories of motivation for donating blood were identified. Pure altruism and warm-glow were mentioned in the top ten most frequent motivations. While pure-altruism did not differentiate 1st time from the repeat donors, warm-glow did, with those with those making their 2nd or 3rd donations being 5 time more likely to express warm-glow and those making their 4th or subsequent donations 3 times more likely. These results add to the growing body of evidence that regular blood donors are more likely to express impure altruistic motives and that focusing on warm-glow interventions may offer the possibility to enhance the retention of blood donors
Positioning Childrenās Voice in Clinical Trials Research: A New Model for Planning, Collaboration, and Reflection
Following the United Nations Convention on the Rights of the Child, there has been considerable growth in research with children about health and services that affect them. Creative methods to engage with children have also been developed. One area where progress has been slower is the inclusion of childrenās perspectives in qualitative research in the context of clinical trials or feasibility studies. Addressing this gap, this article discusses experiences of, and reflections on, the process of researching childrenās views as part of a clinical feasibility study. The article considers what worked well and highlights remaining dilemmas. A new continuum of childrenās engagement in research is presented, designed to assist researchers to make explicit the contingent demands on their research, and to suggest a range of techniques from within the broader fields of health, childhood studies, and education research that could be used to forward qualitative research in clinical contexts
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