10,849 research outputs found
Computing as the 4th “R”: a general education approach to computing education
Computing and computation are increasingly pervading our lives, careers, and societies - a change driving interest in computing education at the secondary level. But what should define a "general education" computing course at this level? That is, what would you want every person to know, assuming they never take another computing course? We identify possible outcomes for such a course through the experience of designing and implementing a general education university course utilizing best-practice pedagogies. Though we nominally taught programming, the design of the course led students to report gaining core, transferable skills and the confidence to employ them in their future. We discuss how various aspects of the course likely contributed to these gains. Finally, we encourage the community to embrace the challenge of teaching general education computing in contrast to and in conjunction with existing curricula designed primarily to interest students in the field
Microscopic Investigation of Vortex Breakdown in a Dividing T-Junction Flow
3D-printed microfluidic devices offer new ways to study fluid dynamics. We
present the first clear visualization of vortex breakdown in a dividing
T-junction flow. By individual control of the inflow and two outflows, we
decouple the effects of swirl and rate of vorticity decay. We show that even
slight outflow imbalances can greatly alter the structure of vortex breakdown,
by creating a net pressure difference across the junction. Our results are
summarized in a dimensionless phase diagram, which will guide the use of vortex
breakdown in T-junctions to achieve specific flow manipulation.Comment: 5 pages, 5 figure
Impact of the various spin and orbital ordering processes on multiferroic properties of orthovanadate DyVO3
The orthovanadate DyVO3 crystal, known to exhibit multiple structural, spin
and orbital ordering transitions, is presently investigated on the basis of
magnetization, heat capacity, resistivity, dielectric and polarization
measurements. Our main result is experimental evidence for the existence of
multiferroicity below a high TC of 108 K over a wide temperature range
including different spin-orbital ordered states. The onset of ferroelectricity
is found to coincide with the antiferromagnetic C-type spin ordering transition
taking place at 108 K, which indicates that DyVO3 belongs to type II
multiferroics exhibiting a coupling between magnetism and ferroelectricity.
Some anomalies detected on the temperature dependence of electric polarization
are discussed with respect to the nature of the spin-orbital ordered states of
the V sublattice and the degree of spin alignment in the Dy sublattice. The
orthovanadates RVO3 (R = rare earth or Y) form an important new category for
searching for high-TC multiferroics.Comment: 25 pages, 7 figures, 68 references, one supplementary material,
Physical Review B, Published 23 July 201
Quantized conductance and its correlation to the supercurrent in a nanowire connected to superconductors
We report conductance and supercurrent of InAs nanowires coupled to
Al-superconducting electrodes with short channel lengths and good Ohmic
contacts. The nanowires are suspended 15\,nm above a local gate electrode. The
charge density in the nanowires can be controlled by a small change in the gate
voltage. For large negative gate voltages, the number of conducting channels is
reduced gradually and we observe a stepwise decrease of both conductance and
critical current before the conductance vanishes completely
Amiral Baudin, nous avons retrouvé le Casimir !: République dominicaine : l'archéologie sous-marine rejoint l'Histoire
Après de nombreuses plongées dans les archives maritimes et dans la mer de la côte nord-dominicaine, une vieille épave pleine de verre s'est révélée être celle d'un brick havrais typique du commerce au long cours français vers Haïti au début du XIXe siècle
14C contamination testing in natural abundance laboratories: a new preparation method using wet chemical oxidation and some experiences
Substances enriched with radiocarbon can easily contaminate samples and laboratories used for natural abundance measurements. We have developed a new method using wet chemical oxidation for swabbing laboratories and equipment to test for 14C contamination. Here, we report the findings of 18 months’ work and more than 800 tests covering studies at multiple locations. Evidence of past and current use of enriched 14C was found at all but one location and a program of testing and communication was used to mitigate its effects. Remediation was attempted with mixed success and depended on the complexity and level of the contamination. We describe four cases from different situations
Charge transport in InAs nanowire Josephson junctions
We present an extensive experimental and theoretical study of the proximity
effect in InAs nanowires connected to superconducting electrodes. We fabricate
and investigate devices with suspended gate-controlled nanowires and
nonsuspended nanowires, with a broad range of lengths and normal-state
resistances. We analyze the main features of the current-voltage
characteristics: the Josephson current, excess current, and subgap current as
functions of length, temperature, magnetic field, and gate voltage, and compare
them with theory. The Josephson critical current for a short-length device, L =
30 nm, exhibits a record high magnitude of 800 nA at low temperature that comes
close to the theoretically expected value. The critical current in all other
devices is typically reduced compared to the theoretical values. The excess
current is consistent with the normal resistance data and agrees well with the
theory. The subgap current shows a large number of structures; some of them are
identified as subharmonic gap structures generated by multiple Andreev
reflection. The other structures, detected in both suspended and nonsuspended
devices, have the form of voltage steps at voltages that are independent of
either the superconducting gap or length of the wire. By varying the gate
voltage in suspended devices, we are able to observe a crossover from typical
tunneling transport at large negative gate voltage, with suppressed subgap
current and negative excess current, to pronounced proximity junction behavior
at large positive gate voltage, with enhanced Josephson current and subgap
conductance as well as a large positive excess current.Comment: 12 pages, 15 figure
In vitro identification and in silico utilization of interspecies sequence similarities using GeneChip(® )technology
BACKGROUND: Genomic approaches in large animal models (canine, ovine etc) are challenging due to insufficient genomic information for these species and the lack of availability of corresponding microarray platforms. To address this problem, we speculated that conserved interspecies genetic sequences can be experimentally detected by cross-species hybridization. The Affymetrix platform probe redundancy offers flexibility in selecting individual probes with high sequence similarities between related species for gene expression analysis. RESULTS: Gene expression profiles of 40 canine samples were generated using the human HG-U133A GeneChip (U133A). Due to interspecies genetic differences, only 14 ± 2% of canine transcripts were detected by U133A probe sets whereas profiling of 40 human samples detected 49 ± 6% of human transcripts. However, when these probe sets were deconstructed into individual probes and examined performance of each probe, we found that 47% of human probes were able to find their targets in canine tissues and generate a detectable hybridization signal. Therefore, we restricted gene expression analysis to these probes and observed the 60% increase in the number of identified canine transcripts. These results were validated by comparison of transcripts identified by our restricted analysis of cross-species hybridization with transcripts identified by hybridization of total lung canine mRNA to new Affymetrix Canine GeneChip(®). CONCLUSION: The experimental identification and restriction of gene expression analysis to probes with detectable hybridization signal drastically increases transcript detection of canine-human hybridization suggesting the possibility of broad utilization of cross-hybridizations of related species using GeneChip technology
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