75 research outputs found
Critical temperature oscillations in magnetically coupled superconducting mesoscopic loops
We study the magnetic interaction between two superconducting concentric
mesoscopic Al loops, close to the superconducting/normal phase transition. The
phase boundary is measured resistively for the two-loop structure as well as
for a reference single loop. In both systems Little-Parks oscillations,
periodic in field are observed in the critical temperature Tc versus applied
magnetic field H. In the Fourier spectrum of the Tc(H) oscillations, a weak
'low frequency' response shows up, which can be attributed to the inner loop
supercurrent magnetic coupling to the flux of the outer loop. The amplitude of
this effect can be tuned by varying the applied transport current.Comment: 9 pages, 7 figures, accepted for publication in Phys. Rev.
Giant vortex state in perforated aluminum microsquares
We investigate the nucleation of superconductivity in a uniform perpendicular
magnetic field H in aluminum microsquares containing a few (2 and 4) submicron
holes (antidots). The normal/superconducting phase boundary T_c(H) of these
structures shows a quite different behavior in low and high fields. In the low
magnetic field regime fluxoid quantization around each antidot leads to
oscillations in T_c(H), expected from the specific sample geometry, and
reminiscent of the network behavior. In high magnetic fields, the T_c(H)
boundaries of the perforated and a reference non-perforated microsquare reveal
cusps at the same values of Phi/Phi_0 (where Phi is the applied flux threading
the total square area and Phi_0 is the superconducting flux quantum), while the
background on T_c(H) becomes quasi-linear, indicating that a giant vortex state
is established. The influence of the actual geometries on T_c(H) is analyzed in
the framework of the linearized Ginzburg-Landau theory.Comment: 14 pages, 6 PS figures, RevTex, accepted for publication in Phys.
Rev.
A Review of the fossil record of turtles of the clade Baenidae
The fossil record of the turtle clade Baenidae ranges from the Early Cretaceous (Aptian—Albian) to the Eocene. The group is present throughout North America during the Early Cretaceous, but is restricted to the western portions of the continents in the Late Cretaceous and Paleogene. No credible remains of the clade have been reported outside of North America to date. Baenids were warmadapted freshwater aquatic turtles that supported high levels of diversity at times through niche partitioning, particularly by adapting to a broad range of dietary preferences ranging from omnivorous to molluscivorous. Current phylogenies place Baenidae near the split of crown-group Testudines. Within Baenidae three more inclusive, named clades are recognized: Baenodda, Palatobaeninae and Eubaeninae. A taxonomic review of the group concludes that of 49 named taxa, 30 are nomina valida, 12 are nomina invalida and 7 are nomina dubia
Comparison of infrared coagulation and rubber band ligation for first and second degree haemorrhoids: a randomised prospective clinical trial
One hundred and thirty seven previously untreated outpatients
with first and second degree haemorrhoids were
allocated at random to treatment by infrared coagulation
(n=66) or rubber band ligation (n= 71). Complete follow
up was obtained in 122 patients (60 who had undergone
infrared coagulation (group 1), and 62 rubber band
ligation (group 2)) at periods from three months to one
year after completion of treatment.
Infrared coagulation produced a satisfactory outcome
in 51 patients (85%): 34 were rendered asymptomatic and
17 improved. Rubber band ligation produced a satisfactory
outcome in 57 patients (92%): 33 were rendered
asymptomatic and 24 improved. Both methods were
equally effective in first and second degree haemorrhoids.
The incidence of side effects, particularly discomfort,
during and after treatment was significantly higher in
those treated by rubber band ligation (p <0 001). This
appeared to be an appreciable deterrent to future patient
compliance. The number of patients losing more than 24
hours from work was higher after rubber band ligation
than after infrared coagulation. The number of treatments
necessary to cure symptoms did not differ significantly
between the two methods. Infrared coagulation was significantly faster than rubber band ligation (p <0-001).
Infrared coagulation is a simple, fast, and effective
outpatient method for the treatment of first and second
degree haemorrhoids with fewer troublesome side effects
and higher patient acceptability than rubber band
ligation
Separation and Identification of Cholesterol Oxidation Products in Dried Egg Preparations
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