967 research outputs found
Using The-Math-You-Need modules in a general education, oceanography course
The Math You Need (TMYN) is a series of on-line tutorials designed for students to increase their mathematical abilities while taking geology and other science courses. The aim of the program is to increase the quantitative abilities of students while demonstrating mathematical applications in an effort to make students more comfortable with and aware of the utility of mathematics. Over two semesters, we implemented targeted-TMYN modules into a general-education oceanography course that is typically populated by non-science majors with a wide variety of mathematical skills before calculus. Students participate voluntarily in TMYN modules with extra credit given for their successful completion. Every class day in the course involves exercises and/or a laboratory that applies oceanographic concepts into which we frequently weave elementary mathematics; also, quantitative questions appear on course exams. For example, understanding rates is particularly fundamental, so exercises frequently concentrate on rate calculations and re-arrangement of simple rate equations and this in-class instruction is complemented by appropriate TMYN modules. To reinforce the importance and utility of mathematics, the instructor continually makes connections between course material and TMYN tutorials.
Pedagogical results are mostly positive. Because participation in TMYN modules is voluntary, two-thirds of students participate partially or wholly in the modules; the complementary fraction do not access a single module. We use pre- and post-tests to recognize gains in student mathematical competence. About one third of students either have lower or no change in performance whereas the balance exhibit varying gains. Some students’ scores saltate markedly by doubling, whereas other students achieve more modest gains. Not surprisingly, larger gains tend to be seen by students that have completed more modules with better scores, but this tendency is not absolute. TMYN modules are looked upon favorably by students. The preponderance of students think that TMYN modules improved their mathematical abilities and helped with the class. We plan continued use of TMYN modules with the goal of augmenting student participation, in anticipation of associated improvement in quantitative skills
Localisation of the human hSuv3p helicase in the mitochondrial matrix and its preferential unwinding of dsDNA
We characterised the human hSuv3p protein belonging to the family of NTPases/helicases. In yeast mitochondria the hSUV3 orthologue is a component of the degradosome complex and participates in mtRNA turnover and processing, while in Caenorhabditis elegans the hSUV3 orthologue is necessary for viability of early embryos. Using immunofluorescence analysis, an in vitro mitochondrial uptake assay and sub‐fractionation of human mitochondria we show hSuv3p to be a soluble protein localised in the mitochondrial matrix. We expressed and purified recombinant hSuv3p protein from a bacterial expression system. The purified enzyme was capable of hydrolysing ATP with a Km of 41.9 µM and the activity was only modestly stimulated by polynucleotides. hSuv3p unwound partly hybridised dsRNA and dsDNA structures with a very strong preference for the latter. The presented analysis of the hSuv3p NTPase/helicase suggests that new functions of the protein have been acquired in the course of evolution
Eficiência de primers relacionados ao metabolismo lipídico em pinhão manso (jatropha curcas l.) para uso em pcr em tempo real.
Teaching Index Numbers to economists
Economic statistics are frequently reported in the form of index numbers. This article considers how the field of Index Numbers should be approached in the teaching of a general economic degree. While the topic finds a natural home in statistics modules, it is emphasised that the area can also be referred to in the teaching of other areas of economics. It is also emphasised that the differences between Index Numbers theory and the practice of compiling economic statistics such as inflation can help students gain a better understanding of applied economic statistics. Methods for assessing learning in the area are also considered and available material to support teaching is also summarised
Baseline natural killer and T cell populations correlation with virologic outcome after regimen simplification to atazanavir/ritonavir alone (ACTG 5201).
OBJECTIVES: Simplified maintenance therapy with ritonavir-boosted atazanavir (ATV/r) provides an alternative treatment option for HIV-1 infection that spares nucleoside analogs (NRTI) for future use and decreased toxicity. We hypothesized that the level of immune activation (IA) and recovery of lymphocyte populations could influence virologic outcomes after regimen simplification.
METHODS: Thirty-four participants with virologic suppression ≥ 48 weeks on antiretroviral therapy (2 NRTI plus protease inhibitor) were switched to ATV/r alone in the context of the ACTG 5201 clinical trial. Flow cytometric analyses were performed on PBMC isolated from 25 patients with available samples, of which 24 had lymphocyte recovery sufficient for this study. Assessments included enumeration of T-cells (CD4/CD8), natural killer (NK) (CD3+CD56+CD16+) cells and cell-associated markers (HLA-DR, CD\u27s 38/69/94/95/158/279).
RESULTS: Eight of the 24 patients had at least one plasma HIV-1 RNA level (VL) \u3e50 copies/mL during the study. NK cell levels below the group median of 7.1% at study entry were associated with development of VL \u3e50 copies/mL following simplification by regression and survival analyses (p = 0.043 and 0.023), with an odds ratio of 10.3 (95% CI: 1.92-55.3). Simplification was associated with transient increases in naïve and CD25+ CD4+ T-cells, and had no impact on IA levels.
CONCLUSIONS: Lower NK cell levels prior to regimen simplification were predictive of virologic rebound after discontinuation of nucleoside analogs. Regimen simplification did not have a sustained impact on markers of IA or T lymphocyte populations in 48 weeks of clinical monitoring.
TRIAL REGISTRATION: ClinicalTrials.gov NCT00084019
Regulation of anaerobic methane oxidation in sediments of the Black Sea
International audienceAnaerobic oxidation of methane (AOM) and sulfate reduction (SRR) were investigated in sediments of the western Black Sea, where methane transport is controlled by diffusion. To understand the regulation and dynamics of methane production and oxidation in the Black Sea, rates of methanogenesis, AOM, and SRR were determined using radiotracers in combination with pore water chemistry and stable isotopes. On the shelf of the Danube paleo-delta and the Dnjepr Canyon, AOM did not consume methane effectively and upwards diffusing methane created an extended sulfate-methane transition zone (SMTZ) that spread over more than 2.5 m and was located in formerly limnic sediment. Measurable AOM rates occurred mainly in the lower part of the SMTZ, sometimes even at depths where sulfate seemed to be unavailable. The inefficiency of methane oxidation appears to be linked to the limnic history of the sediment, since in all cores methane was completely oxidized at the limnic-marine transition. The upward tailing of methane was less pronounced in a core from the deep sea in the area of the Dnjepr Canyon, the only station with a SMTZ close to the marine deposits. Sulfate reduction rates were mostly extremely low, and in the SMTZ were even lower than AOM rates. Rates of bicarbonate-based methanogenesis were below detection limit in two of the cores, but ?13C values of methane indicate a biogenic origin. The most depleted ?13C-signal was found in the SMTZ of the core from the deep sea, most likely as a result of carbon recycling between AOM and methanogenesis
Isochronal annealing effects on local structure, crystalline fraction, and undamaged region size of radiation damage in Ga-stabilized -Pu
The effects on the local structure due to self-irradiation damage of Ga
stabilized -Pu stored at cryogenic temperatures have been examined
using extended x-ray absorption fine structure (EXAFS) experiments. Extensive
damage, seen as a loss of local order, was evident after 72 days of storage
below 15 K. The effect was observed from both the Pu and Ga sites, although
less pronounced around Ga. Isochronal annealing was performed on this sample to
study the annealing processes that occur between cryogenic and room temperature
storage conditions, where damage is mostly reversed. Damage fractions at
various points along the annealing curve have been determined using an
amplitude-ratio method, standard EXAFS fitting, and a spherical crystallite
model, and provide information complementary to previous electrical
resistivity- and susceptibility-based isochronal annealing studies. The use of
a spherical crystallite model accounts for the changes in EXAFS spectra using
just two parameters, namely, the crystalline fraction and the particle radius.
Together, these results are discussed in terms of changes to the local
structure around Ga and Pu throughout the annealing process and highlight the
unusual role of Ga in the behavior of the lowest temperature anneals.Comment: 13 pages, 10 figure
Ensaios de avaliação de cultivares e linhagens de cevada conduzidos na FAPA, safras 2007 e 2008.
Powerpoint
Dynamics of path aggregation in the presence of turnover
We investigate the slow time scales that arise from aging of the paths during
the process of path aggregation. This is studied using Monte-Carlo simulations
of a model aiming to describe the formation of fascicles of axons mediated by
contact axon-axon interactions. The growing axons are represented as
interacting directed random walks in two spatial dimensions. To mimic axonal
turnover, random walkers are injected and whole paths of individual walkers are
removed at specified rates. We identify several distinct time scales that
emerge from the system dynamics and can exceed the average axonal lifetime by
orders of magnitude. In the dynamical steady state, the position-dependent
distribution of fascicle sizes obeys a scaling law. We discuss our findings in
terms of an analytically tractable, effective model of fascicle dynamics.Comment: 6 pages, 5 figures; changed the order of presentation, rewritten the
abstract and introduction, changed the title, expanded discussions; the main
results remain the sam
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