8,114 research outputs found
Presentation of the acoustic and aerodynamic results of the Aladin 2 concept qualification testing
Wind tunnel tests were conducted of a scale model of the Aladin 2 aircraft. The propulsion system configuration is described and the air flow caused by jet ejection is analyzed. Three dimensional flow studies in the vicinity of the engine installation were made. Diagrams of the leading and trailing edge flaps are provided. Graphs are developed to show the aerodynamic performance under conditions of various airspeed and flap deflection
Effect of small mapping population sizes on reliability of quantitative trait locus (QTL) mapping
A limitation of quantitative trait loci (QTL) mapping is that accuracy of determining QTL position and effects are largely determined by population size. Despite the importance of this concept, known as the "Beavis effect there has generally been a lack of understanding by molecular geneticists and breeders. One possible explanation for this may be that this concept has been explored by using computer simulations and that these findings may not be clearly understood. In this study, we demonstrated the effect of population size on the accuracy of determining QTL positions and effects in a simple and concise manner. Simulated data was generated for extremely large mapping populations (n = 1000) and smaller mapping populations (n = 94 or n = 190) were obtained by random sampling. Populations were defined to segregate for either three or five QTLs with heritabilities of h2 = 0.75 or h2 = 0.50. When small populations were used, errors were detected in determining QTL positions, and in some cases, QTLs were not detected (that is, false negatives) especially when h2 = 0.50. More importantly, R2 values were overestimated or underestimated. Composite interval mapping was more reliable for detecting QTLs compared to simple interval mapping. These findings have important implications for QTLs which are selected in breeding programs via marker-assisted selection.Key words: Quantitative trait loci (QTL) mapping, Beavis effect, population size, confidence intervals, marker-assisted selection
Joubert syndrome diagnosed renally late
Joubert syndrome is a genetically heterogeneous multisystem disorder typically diagnosed in childhood. Nephronophthisis is the most common renal pathology in Joubert syndrome, and renal failure usually occurs in childhood or in young adults. We report a 61-year-old female diagnosed with AHI1-related oculorenal Joubert syndrome, who presented initially with decline in renal function in her 50s. Our report describes exceptionally late presentation of renal disease in Joubert syndrome and highlights the importance of continued renal function monitoring in older adults with Joubert syndrome
NLO-QCD Corrections to Dilepton Production in the Randall-Sundrum Model
The dilepton production process at hadron colliders in the Randall-Sundrum
(RS) model is studied at next-to-leading order in QCD. The NLO-QCD corrections
have been computed for the virtual graviton exchange process in the RS model,
in addition to the usual gamma, Z-mediated processes of standard Drell-Yan.
K-factors for the cross-sections at the LHC and Tevatron for differential in
the invariant mass, Q, and the rapidity, Y, of the lepton pair are presented.
We find the K-factors are large over substantial regions of the phase space.Comment: 24 pages, 12 figure
Transcriptional down-regulation of the retinoblastoma protein is associated with differentiation and apoptosis in human colorectal epithelial cells
The aim of this study was to investigate the regulation of Rb protein expression in relation to increased differentiation and induction of apoptosis in colonic epithelial cells. In vivo, Rb protein expression was found to be down-regulated towards the top of the normal colonic crypt, coincident with the region of differentiation and apoptosis, but highly expressed in colonic carcinoma tissue. Using in vitro models to study the regulation of Rb expression in pre-malignant colonic epithelial cells, we have been able to show for the first time that Rb protein expression is transcriptionally down-regulated in differentiated pre-malignant cells (in post-confluent cultures) but not in malignant colorectal epithelial cells. Furthermore, suppression of rb protein function by the HPV-E7 viral oncoprotein increased both spontaneous and DNA damage-induced apoptosis. These results suggest that Rb is able to act as a survival factor in colonic epithelial cells by suppressing apoptosis, and that over-expression of pRb in colorectal tumour cells can cause a loss of sensitivity to apoptotic signalling, resulting in aberrant cell survival and resistance to therapy. © 2001 Cancer Research Campaign http://www.bjcancer.co
Effectiveness of late-life depression interventions on functional limitations:A systematic review
Depression is one of the most prevalent mental disorders in older adults and leads to considerable decreases in health, well-being, and impaired functioning. Intervention studies have focused on the effects on symptomatic recovery, and most do not include functional recovery as an outcome. Reduction of functional limitations as a treatment goal in old-age psychiatry aligns with the values of older persons. The objective of this review was therefore to evaluate the effectiveness of late-life depression interventions on functional limitations. This systematic review identified 15 randomized controlled trials in which the effectiveness of different interventions on functional limitations was evaluated in patients with late-life depression. The interventions were categorized into four categories: psychological interventions, drug treatment, physical exercise, and collaborative care. Multicomponent and collaborative-care interventions appear to be the most promising for improvement of functional limitations, particularly in primary care and community-dwelling populations of older persons with symptoms of depression. There is, however, a lack of evidence regarding studies in specialized mental health care
The role of B-Cell Lymphoma-3 (BCL-3) in enabling the hallmarks of cancer:implications for the treatment of colorectal carcinogenesis
Low temperature (down to 450° C) annealed TiAl contacts on N-type gallium nitride characterized by differential scanning calorimetry
International audienceThis work reports on Differential Scanning Calorimetry (DSC) measurements performed on Ti-Al metallic layers stacks deposited on n+-GaN. The aim is to get better understanding of the mechanisms leading to ohmic contact formation during the annealing stage. Two exothermic peaks were found, one below 500°C and the other one around 660°C. They can be respectively attributed to Al3Ti and Al2Ti compounds formation. The locations of these peaks provide clear evidence of solid-solid reac-tions. Lowest contact resistance is well correlated with the presence of Al3Ti compound, corresponding to Al(200nm)/Ti(50nm) stoichiometric ratio. Subsequently, Al(200 nm)Ti(50 nm) stacks on n+-GaN were annealed from 400°C to 650°C. Specific Contact Resistivity (SCR) values stay in the mid 10-5 Ω.cm² range for annealing temperatures between 450°C and 650°C. Such low-temperature annealed contacts on n+-GaN may open new device processing routes, simpler and cheaper, in which Ohmic and Schottky contacts are annealed together
Behavioral Modernity and the Cultural Transmission of Structured Information: The Semantic Axelrod Model
Cultural transmission models are coming to the fore in explaining increases
in the Paleolithic toolkit richness and diversity. During the later
Paleolithic, technologies increase not only in terms of diversity but also in
their complexity and interdependence. As Mesoudi and O'Brien (2008) have shown,
selection broadly favors social learning of information that is hierarchical
and structured, and multiple studies have demonstrated that teaching within a
social learning environment can increase fitness. We believe that teaching also
provides the scaffolding for transmission of more complex cultural traits.
Here, we introduce an extension of the Axelrod (1997} model of cultural
differentiation in which traits have prerequisite relationships, and where
social learning is dependent upon the ordering of those prerequisites. We
examine the resulting structure of cultural repertoires as learning
environments range from largely unstructured imitation, to structured teaching
of necessary prerequisites, and we find that in combination with individual
learning and innovation, high probabilities of teaching prerequisites leads to
richer cultural repertoires. Our results point to ways in which we can build
more comprehensive explanations of the archaeological record of the Paleolithic
as well as other cases of technological change.Comment: 24 pages, 7 figures. Submitted to "Learning Strategies and Cultural
Evolution during the Paleolithic", edited by Kenichi Aoki and Alex Mesoudi,
and presented at the 79th Annual Meeting of the Society for American
Archaeology, Austin TX. Revised 5/14/1
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