516 research outputs found
Effect of cation size variance on spin and orbital order in Eu(LaY)VO
We have investigated the -ion ( = rare earth or Y) size variance effect
on spin/orbital order in Eu(LaY)VO. The
size variance disturbs one-dimensional orbital correlation in -type
spin/-type orbital ordered states and suppresses this spin/orbital order. In
contrast, it stabilizes the other spin/orbital order. The results of neutron
and resonant X-ray scattering denote that in the other ordered phase, the
spin/orbital patterns are -type/-type, respectively.Comment: 4 pages, 4 figures, accepted to Rapid Communication in Physical
Review
Study of the relationship between solar activity and terrestrial weather
Evidence for some connection between weather and solar related phenomena is presented. Historical data of world wide temperature variations with relationship to change in solar luminosity are examined. Several test methods for estimating the statistical significance of such phenomena are discussed in detail
Optimization of Monte-Carlo calculations of the effective potential
We study Monte Carlo calculations of the effective potential for a scalar
field theory using three techniques. One of these is a new method proposed and
tested for the first time. In each case we extract the renormalised quantities
of the theory. The system studied in our calculations is a one component
model in two dimensions. We apply these methods to both the weak and
strong coupling regime. In the weak coupling regime we compare our results for
the renormalised quantities with those obtained from two-loop lattice
perturbation theory. Our results are verified in the strong coupling regime
through comparison with the strong coupling expansion. We conclude that
effective potential methods, when suitably chosen, can be accurate tools in
calculations of the renormalised parameters of scalar field theories.Comment: 26 pages of LaTeX, uses psfig.sty with 6 figures. Entire manuscript
available as a postscript file via WWW at
http://www.physics.adelaide.edu.au/theory/papers/ADP-97-13.T250-abs.html or
via anonymous ftp at
ftp://bragg.physics.adelaide.edu.au/pub/theory/ADP-97-13.T250.p
Thermodynamics of heterogeneous crystal nucleation in contact and immersion modes
One of most intriguing problems of heterogeneous crystal nucleation in
droplets is its strong enhancement in the contact mode (when the foreign
particle is presumably in some kind of contact with the droplet surface)
compared to the immersion mode (particle immersed in the droplet). Many
heterogeneous centers have different nucleation thresholds when they act in
contact or immersion modes, indicating that the mechanisms may be actually
different for the different modes. Underlying physical reasons for this
enhancement have remained largely unclear. In this paper we present a model for
the thermodynamic enhancement of heterogeneous crystal nucleation in the
contact mode compared to the immersion one. To determine if and how the surface
of a liquid droplet can thermodynamically stimulate its heterogeneous
crystallization, we examine crystal nucleation in the immersion and contact
modes by deriving and comparing with each other the reversible works of
formation of crystal nuclei in these cases. As a numerical illustration, the
proposed model is applied to the heterogeneous nucleation of Ih crystals on
generic macroscopic foreign particles in water droplets at T=253 K. Our results
show that the droplet surface does thermodynamically favor the contact mode
over the immersion one. Surprisingly, our numerical evaluations suggest that
the line tension contribution to this enhancement from the contact of three
water phases (vapor-liquid-crystal) may be of the same order of magnitude as or
even larger than the surface tension contribution
Live lecture versus video podcast in undergraduate medical education: A randomised controlled trial
<p>Abstract</p> <p>Background</p> <p>Information technology is finding an increasing role in the training of medical students. We compared information recall and student experience and preference after live lectures and video podcasts in undergraduate medical education.</p> <p>Methods</p> <p>We performed a crossover randomised controlled trial. 100 students were randomised to live lecture or video podcast for one clinical topic. Live lectures were given by the same instructor as the narrator of the video podcasts. The video podcasts comprised Powerpointâ„¢ slides narrated using the same script as the lecture. They were then switched to the other group for a second clinical topic. Knowledge was assessed using multiple choice questions and qualitative information was collected using a questionnaire.</p> <p>Results</p> <p>No significant difference was found on multiple choice questioning immediately after the session. The subjects enjoyed the convenience of the video podcast and the ability to stop, review and repeat it, but found it less engaging as a teaching method. They expressed a clear preference for the live lecture format.</p> <p>Conclusions</p> <p>We suggest that video podcasts are not ready to replace traditional teaching methods, but may have an important role in reinforcing learning and aiding revision.</p
Gastrointestinal Stromal Tumor Mimicking Arteriovenous Malformation of the Jejunum
There have been case reports of small intestinal gastrointestinal stromal tumors (GISTs) complicated with arteriovenous malformation (AVM) and angiodysplasia and exhibiting intense tumor staining. Herein we report a GIST of the small intestine that showed tumor staining and early venous return on imaging studies, and so the patient was suspected to have AVM. A 62-year-old male presented with intermittent pain in the left abdominal region. Contrast-enhanced computed tomography revealed a 15-mm-long spindle-shaped mass showing intense tumor staining and early venous return through the jejunal vein. In the arterial phase, the attenuation value of the tumor was 250 Hounsfield units. Color Doppler ultrasonography simultaneously delineated vessels extending from the serosal side and turbulent signals showing a mosaic pattern in the tumor. On angiography, intense staining was observed in the peripheral part of the second branch of the jejunal artery. Although these findings suggested AVM, the tumor was diagnosed as a GIST based on pathological examination of the resected specimens. In this case, no AVM or change in vascular density was noted despite the careful examination of pathological specimens, and the cause of the tumor staining remained unknown
Chromogenic detection of yam mosaic virus by closed-tube reverse transcription loop-mediated isothermal amplification (CT-RT-LAMP)
A closed-tube reverse transcription loop-mediated isothermal amplification (CT-RT-LAMP) assay was developed for the detection of yam mosaic virus (YMV, genus Potyvirus) infecting yam (Dioscorea spp.). The assay uses a set of six oligonucleotide primers targeting the YMV coat protein region, and the amplification products in YMV-positive samples are visualized by chromogenic detection with SYBR Green I dye. The CT-RT-LAMP assay detected YMV in leaf and tuber tissues of infected plants. The assay is 100 times more sensitive in detecting YMV than standard RT-PCR, while maintaining the same specificity
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