992 resultados para 505


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The format of grant applications should be updated to incorporate multimedia video. This would help researchers to convey complex topics to grant-review panels. If time-poor research panels cannot quickly grasp the scientific ideas presented in a paper application, other factors, such as author affiliations and track records, may disproportionately influence project rankings...

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Various models for the crystal structure of hydronium jarosite were determined from Rietveld refinements against neutron powder diffraction patterns collected at ambient temperature and also single-crystal X-ray diffraction data. The possibility of a lower symmetry space group for hydronium jarosite that has been suggested by the literature was investigated. It was found the space group is best described as R3¯m, the same for other jarosite minerals. The hydronium oxygen atom was found to occupy the 3¯m site (3a Wyckoff site). Inadequately refined hydronium bond angles and bond distances without the use of restraints are due to thermal motion and disorder of the hydronium hydrogen atoms across numerous orientations. However, the acquired data do not permit a precise determination of these orientations; the main feature up/down disorder of hydronium is clear. Thus, the highest symmetry model with the least disorder necessary to explain all data was chosen: The hydronium hydrogen atoms were modeled to occupy an m (18 h Wyckoff site) with 50 % fractional occupancy, leading to disorder across two orientations. A rigid body description of the hydronium ion rotated by 60° with H–O–H bond angles of 112° and O–H distances of 0.96 Å was optimal. This rigid body refinement suggests that hydrogen bonds between hydronium hydrogen atoms and basal sulfate oxygen atoms are not predominant. Instead, hydrogen bonds are formed between hydronium hydrogen atoms and hydroxyl oxygen atoms. The structure of hydronium alunite is expected to be similar given that alunite supergroup minerals are isostructural.

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OBJECTIVES: To compare the classification accuracy of previously published RT3 accelerometer cut-points for youth using energy expenditure, measured via portable indirect calorimetry, as a criterion measure. DESIGN: Cross-sectional cross-validation study. METHODS: 100 children (mean age 11.2±2.8 years, 61% male) completed 12 standardized activities trials (3 sedentary, 5 lifestyle and 4 ambulatory) while wearing an RT3 accelerometer. V˙O2 was measured concurrently using the Oxycon Mobile portable calorimeter. Cut-points by Vanhelst (VH), Rowlands (RW), Chu (CH), Kavouras (KV) and the RT3 manufacturer (RT3M) were used to classify PA intensity as sedentary (SED), light (LPA), moderate (MPA) or vigorous (VPA). Classification accuracy was evaluated using the area under the Receiver Operating Characteristic curve (ROC-AUC) and weighted Kappa (κ). RESULTS: For moderate-to-vigorous PA (MVPA), VH, KV and RW exhibited excellent accuracy classification (ROC-AUC≥0.90), while the CH and RT3M exhibited good classification accuracy (ROC-AUC>0.80). Classification accuracy for LPA was fair to poor (ROC-AUC<0.76). For SED, VH exhibited excellent classification accuracy (ROC-AUC>0.90), while RW, CH, and RT3M exhibited good classification accuracy (ROC-AUC>0.80). Kappa statistics ranged from 0.67 (VH) to 0.55 (CH). CONCLUSIONS: All cut-points provided acceptable classification accuracy for SED and MVPA, but limited accuracy for LPA. On the basis of classification accuracy over all four levels of intensity, the use of the VH cut-points is recommended.

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Mammographic density (MD) adjusted for age and body mass index (BMI) is a strong heritable breast cancer risk factor; however, its biological basis remains elusive. Previous studies assessed MD-associated histology using random sampling approaches, despite evidence that high and low MD areas exist within a breast and are negatively correlated with respect to one another. We have used an image-guided approach to sample high and low MD tissues from within individual breasts to examine the relationship between histology and degree of MD. Image-guided sampling was performed using two different methodologies on mastectomy tissues (n = 12): (1) sampling of high and low MD regions within a slice guided by bright (high MD) and dark (low MD) areas in a slice X-ray film; (2) sampling of high and low MD regions within a whole breast using a stereotactically guided vacuum-assisted core biopsy technique. Pairwise analysis accounting for potential confounders (i.e. age, BMI, menopausal status, etc.) provides appropriate power for analysis despite the small sample size. High MD tissues had higher stromal (P = 0.002) and lower fat (P = 0.002) compositions, but no evidence of difference in glandular areas (P = 0.084) compared to low MD tissues from the same breast. High MD regions had higher relative gland counts (P = 0.023), and a preponderance of Type I lobules in high MD compared to low MD regions was observed in 58% of subjects (n = 7), but did not achieve significance. These findings clarify the histologic nature of high MD tissue and support hypotheses regarding the biophysical impact of dense connective tissue on mammary malignancy. They also provide important terms of reference for ongoing analyses of the underlying genetics of MD.

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The aim of this paper is to estimate the productivity change of Nigerian insurance companies and to rank the companies analysed in the sample according to their productivity score. This benchmark exercise provides the companies analysed with a view of how their relative productivity can be upgraded. For this purpose, the non-parametric Luenberger productivity model is used. For comparative purposes, the non-parametric Luenberger-Hicks-Moorsteen productivity indicator is also used. The companies are ranked according to their total productivity for the period 1994-2005, using both models, which produce variations in the respective results. Economic implications arising from the study are derived.

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There is increased accountability of initial teacher education (ITE) programs in Australia to develop Graduate teachers who are better prepared. Most ITE programs have been designed using Pedagogical Content Knowledge. Informed by the growing Technological Pedagogical Content Knowledge (TPACK) research, this journal article suggests that ITE programs need to develop Graduate teachers who have the TPACK capabilities to use technologies to support teaching and student learning. Insights from the research and evaluation of the Teaching Teachers for the Future (TTF) Project, which was guided by the TPACK conceptualisation, are provided. The TTF Project, which involved all Higher Education Institutions providing ITE programs in Australia, drew upon the TPACK conceptualisation. The TTF Project research and evaluation included the development and administration of a TTF TPACK Survey and the implementation of the Most Significant Change Methodology. Key findings resulting from the employment of these methodologies are summarised to provide guidance to inform the improvement of ITE programs to develop Graduate TPACK capabilities.

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Peptides constructed from α-helical subunits of the Lac repressor protein (LacI) were designed then tailored to achieve particular binding kinetics and dissociation constants for plasmid DNA purification and detection. Surface plasmon resonance was employed for quantification and characterization of the binding of double stranded Escherichia coli plasmid DNA (pUC19) via the lac operon (lacO) to "biomimics" of the DNA binding domain of LacI. Equilibrium dissociation constants (K D), association (k a), and dissociation rates (k d) for the interaction between a suite of peptide sequences and pUC19 were determined. K D values measured for the binding of pUC19 to the 47mer, 27mer, 16mer, and 14mer peptides were 8.8 ± 1.3 × 10 -10 M, 7.2 ± 0.6 × 10 -10 M, 4.5 ± 0.5 × 10 -8 M, and 6.2 ± 0.9 × 10 -6 M, respectively. These findings show that affinity peptides, composed of subunits from a naturally occurring operon-repressor interaction, can be designed to achieve binding characteristics suitable for affinity chromatography and biosensor devices.

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Railway capacity determination and expansion are very important topics. In prior research, the competition between different entities such as train services and train types, on different network corridors however have been ignored, poorly modelled, or else assumed to be static. In response, a comprehensive set of multi-objective models have been formulated in this article to perform a trade-off analysis. These models determine the total absolute capacity of railway networks as the most equitable solution according to a clearly defined set of competing objectives. The models also perform a sensitivity analysis of capacity with respect to those competing objectives. The models have been extensively tested on a case study and their significant worth is shown. The models were solved using a variety of techniques however an adaptive E constraint method was shown to be most superior. In order to identify only the best solution, a Simulated Annealing meta-heuristic was implemented and tested. However a linearization technique based upon separable programming was also developed and shown to be superior in terms of solution quality but far less in terms of computational time.

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The objectives of this study were (A) to record the inner prosthesis loading during activities of daily living (ADL), (B) to present a set of variables comparing loading data, and (C) to provide an example of characterisation of two prostheses. The load was measured at 200 Hz using a multi-axial transducer mounted between the residuum and the knee of an individual with unilateral transfemoral amputation fitted with a bone-anchored prosthesis. The load was measured while using two different prostheses including a mechanically (PRO1) and a microprocessor controlled (PRO2) knee during six ADL. The characterisation of prosthesis was achieved using a set of variables split into four categories, including temporal characteristics, maximum loading, loading slopes and impulse. Approximately 360 gait cycles were analysed for each prosthesis. PRO1 showed a cadence improved by 19% and 7%, a maximum force on the long axis reduced by 11% and 19%, as well as an impulse reduced by 32% and 15% during descent of incline and stairs compared to PRO2, respectively. This work confirmed that the proposed apparatus and characterisation can reveal how changes of prosthetic components are translated into inner loading.

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The structures of the isomorphous potassium and rubidium polymeric coordination complexes with 4-nitrobenzoic acid, poly[mu2-aqua-aqua-mu3-(4-nitrobenzoato)-potassium], [K(C7H4N2O2)(H2O)2]n, (I) and poly[mu3-aqua-aqua-mu5-(4-nitrobenzoato)-rubidium], [Rb(C7H4N2O2)(H2O)2]n, (II) have been determined. In (I) the very distorted KO6 coordination sphere about the K+ centres in the repeat unit comprise two bridging nitro O-atom donors, a single bridging carboxyl O-atom donor and two water molecules, one of which is bridging. In the the Rb complex (II), the same basic MO6 coordination is found in the repeat unit but is expanded to RbO9 through a slight increase in the accepted Rb-O bond length range and includes an additional Rb-O(carboxyl) bond, completing a bidentate O,O'-chelate interaction, and additional bridging Rb-Onitro) and Rb-O(water) bonds. The comparative K-O and Rb-O bond length ranges are 2.738(3)-3.002(3)Ang. (I) and 2.884(2)-3.182(2)Ang. (II). The structure of (II) is also isomorphous as well as isostructural with the known structure of the nine-coordinate caesium 4-nitrobenzoate analogue, [Cs(C7H4N2O~2~)(H~2~O)2]n, (III) in which the Cs---O range is 3.047(4)-3.338(4)Ang. In all three complexes, common basic polymeric extensions are found, including two different centrosymmetric bridging interactions through both water and nitro groups as well as extensions along c through the p-related carboxyl group, giving a two-dimensional structure in (I). In (II) and (III), three-dimensional structures are generated through additional bridges through the nitro and water O-atoms. In all structures, both water molecules are involved in similar intra-polymer O-H...O hydrogen-bonding interactions to both carboxyl as well as water O-atom acceptors. A comparison of the varied coordination behaviour of the full set of Li-Cs salts with 4-nitrobenzoic acid is also made.

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This article considers the integral role played by patent law in respect of stem cell research. It highlights concerns about commercialization, access to essential medicines and bioethics. The article maintains that there is a fundamental ambiguity in the Patents Act 1990 (Cth) as to whether stem cell research is patentable subject matter. There is a need to revise the legislation in light of the establishment of the National Stem Cell Centre and the passing of the Research Involving Embryos Act 2002 (Cth). The article raises concerns about the strong patent protection secured by the Wisconsin Alumni Research Foundation and Geron Corporation in respect of stem cell research in the United States. It contends that a number of legal reforms could safeguard access to stem cell lines, and resulting drugs and therapies. Finally, this article explores how ethical concerns are addressed within the framework of the European Biotechnology Directive. It examines the decision of the European Patent Office in relation to the so-called Edinburgh patent, and the inquiry of the European Group on Ethics in Science and New Technologies into The Ethical Aspects of Patenting Involving Human Stem Cells.

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Brain asymmetry has been a topic of interest for neuroscientists for many years. The advent of diffusion tensor imaging (DTI) allows researchers to extend the study of asymmetry to a microscopic scale by examining fiber integrity differences across hemispheres rather than the macroscopic differences in shape or structure volumes. Even so, the power to detect these microarchitectural differences depends on the sample size and how the brain images are registered and how many subjects are studied. We fluidly registered 4 Tesla DTI scans from 180 healthy adult twins (45 identical and fraternal pairs) to a geometrically-centered population mean template. We computed voxelwise maps of significant asymmetries (left/right hemisphere differences) for common fiber anisotropy indices (FA, GA). Quantitative genetic models revealed that 47-62% of the variance in asymmetry was due to genetic differences in the population. We studied how these heritability estimates varied with the type of registration target (T1- or T2-weighted) and with sample size. All methods consistently found that genetic factors strongly determined the lateralization of fiber anisotropy, facilitating the quest for specific genes that might influence brain asymmetry and fiber integrity.

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A simulation model (PCPF-B) was developed based on the PCPF-1 model to predict the runoff of pesticides from paddy plots to a drainage canal in a paddy block. The block-scale model now comprises three modules: (1) a module for pesticide application, (2) a module for pesticide behavior in paddy fields, and (3) a module for pesticide concentration in the drainage canal. The PCPF-B model was first evaluated by published data in a single plot and then was applied to predict the concentration of bensulfuron-methyl in one paddy block in the Sakura river basin, Ibaraki, Japan, where a detailed field survey was conducted. The PCPF-B model simulated well the behavior of bensulfuron-methyl in individual paddy plots. It also reflected the runoff pattern of bensulfuron-methyl at the block outlet, although overestimation of bensulfuronmethyl concentrations occurred due to uncertainty in water balance estimation. Application of water management practice such as water-holding period and seepage control also affected the performance of the model. A probabilistic approach may be necessary for a comprehensive risk assessment in large-scale paddy areas.

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The specific activity and content of cytochrome oxidase in the rough endoplasmic reticulum--mitochondrion complex are higher than in the mitochondrial fraction. Radiolabelling studies with the use of hepatocytes and isolated microsomal and rough endoplasmic reticulum--mitochondrion fractions, followed by immunoprecipitation with anti-(cytochrome oxidase) antibody, reveal that the nuclear-coded cytoplasmic subunits of cytochrome oxidase are preferentially synthesized in the latter fraction. The results have a bearing on the mechanism of transport of these subunits into mitochondria.