2,273 research outputs found
Math Speak and Students\u27 Justifications Promote Deeper Understanding of Mathematics Concepts
The problem of resonance in technology usage
Various information system tools and techniques are analyzed. A case study is presented which draws together the issues raised in three distinct cases. This case study shows a typical progression from the selection of an analysis methodology, to the adoption of an automated tool for specification and documentation, and the difficulty of fitting these into an existing life cycle development methodology
Fermi-LAT and Suzaku Observations of the Radio Galaxy Centaurus B
Centaurus B is a nearby radio galaxy positioned in the Southern hemisphere
close to the Galactic plane. Here we present a detailed analysis of about 43
months of accumulated Fermi-LAT data of the gamma-ray counterpart of the source
initially reported in the 2nd Fermi-LAT catalog, and of newly acquired Suzaku
X-ray data. We confirm its detection at GeV photon energies, and analyze the
extension and variability of the gamma-ray source in the LAT dataset, in which
it appears as a steady gamma-ray emitter. The X-ray core of Centaurus B is
detected as a bright source of a continuum radiation. We do not detect however
any diffuse X-ray emission from the known radio lobes, with the provided upper
limit only marginally consistent with the previously claimed ASCA flux. Two
scenarios that connect the X-ray and gamma-ray properties are considered. In
the first one, we assume that the diffuse non-thermal X-ray emission component
is not significantly below the derived Suzaku upper limit. In this case,
modeling the inverse-Compton emission shows that the observed gamma-ray flux of
the source may in principle be produced within the lobes. This association
would imply that efficient in-situ acceleration of the radiating electrons is
occurring and that the lobes are dominated by the pressure from the
relativistic particles. In the second scenario, with the diffuse X-ray emission
well below the Suzaku upper limits, the lobes in the system are instead
dominated by the magnetic pressure. In this case, the observed gamma-ray flux
is not likely to be produced within the lobes, but instead within the nuclear
parts of the jet. By means of synchrotron self-Compton modeling we show that
this possibility could be consistent with the broad-band data collected for the
unresolved core of Centaurus B, including the newly derived Suzaku spectrum.Comment: Accepted for publication in A&A. 11 page
Systematic study of Mn-doping trends in optical properties of (Ga,Mn)As
We report on a systematic study of optical properties of (Ga,Mn)As epilayers
spanning the wide range of accessible substitutional Mn_Ga dopings. The growth
and post-growth annealing procedures were optimized for each nominal Mn doping
in order to obtain films which are as close as possible to uniform
uncompensated (Ga,Mn)As mixed crystals. We observe a broad maximum in the
mid-infrared absorption spectra whose position exhibits a prevailing blue-shift
for increasing Mn-doping. In the visible range, a peak in the magnetic circular
dichroism blue shifts with increasing Mn-doping. These observed trends confirm
that disorder-broadened valence band states provide a better one-particle
representation for the electronic structure of high-doped (Ga,Mn)As with
metallic conduction than an energy spectrum assuming the Fermi level pinned in
a narrow impurity band.Comment: 22 pages, 14 figure
Crystallization diagram for antisolvent crystallization of lactose : using design of experiments to investigate continuous mixing- induced supersaturation
This study investigates the effects of key process parameters of continuous mixing-induced supersaturation on the antisolvent crystallization of lactose using D-optimal Design of Experiments (DoE). Aqueous solutions of lactose were mixed isothermally with antisolvents using a concentric capillary mixer. Process parameters investigated were the choice of antisolvent (acetone or isopropanol), concentration of lactose solution, total mass flow rate, and the ratio of mass flow rates of lactose solution and antisolvent. Using a D-optimal DoE a statistically significant sample set was chosen to explore and quantify the effects of these parameters. The responses measured were the solid state of the lactose crystallized, induction time, solid yield and particle size. Mixtures of α-lactose monohydrate and β-lactose were crystallized under most conditions with β-lactose content increasing with increasing amount of antisolvent. Pure α-lactose monohydrate was crystallized using acetone as the antisolvent, with mass flow ratios near 1:1, and near saturated solutions of lactose. A higher resolution DoE was adopted for acetone and was processed using multivariate methods to obtain a crystallization diagram of lactose. The model was used to create an optimized process to produce α-lactose monohydrate and predicted results agreed well with those obtained experimentally, validating the model. The solid state of lactose, induction time, and solid yield were accurately predicted
Synthesis and Electronic Properties of D–A–D Triads Based on 3-Alkoxy-4-cyanothiophene and Benzothienothiophene Blocks
International audienc
Shortcomings of short hairpin RNA-based transgenic RNA interference in mouse oocytes
<p>Abstract</p> <p>Background</p> <p>RNA interference (RNAi) is a powerful approach to study a gene function. Transgenic RNAi is an adaptation of this approach where suppression of a specific gene is achieved by expression of an RNA hairpin from a transgene. In somatic cells, where a long double-stranded RNA (dsRNA) longer than 30 base-pairs can induce a sequence-independent interferon response, short hairpin RNA (shRNA) expression is used to induce RNAi. In contrast, transgenic RNAi in the oocyte routinely employs a long RNA hairpin. Transgenic RNAi based on long hairpin RNA, although robust and successful, is restricted to a few cell types, where long double-stranded RNA does not induce sequence-independent responses. Transgenic RNAi in mouse oocytes based on a shRNA offers several potential advantages, including simple cloning of the transgenic vector and an ability to use the same targeting construct in any cell type.</p> <p>Results</p> <p>Here we report our experience with shRNA-based transgenic RNAi in mouse oocytes. Despite optimal starting conditions for this experiment, we experienced several setbacks, which outweigh potential benefits of the shRNA system. First, obtaining an efficient shRNA is potentially a time-consuming and expensive task. Second, we observed that our transgene, which was based on a common commercial vector, was readily silenced in transgenic animals.</p> <p>Conclusions</p> <p>We conclude that, the long RNA hairpin-based RNAi is more reliable and cost-effective and we recommend it as a method-of-choice when a gene is studied selectively in the oocyte.</p
The role of environmental exposures and the epigenome in health and disease
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152782/1/em22311_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152782/2/em22311.pd
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