493 research outputs found
Observation of exponential spectra and Lorentzian pulses in the TJ-K stellarator
An experimental investigation of the low-frequency density fluctuations in the plasma edge region of the TJ-K stellarator [N. Krause et al., Rev. Sci. Inst. 73, 3474 (2002)] finds that the ensemble- averaged frequency spectra exhibit a near exponential frequency dependence whose origin can be traced to individual pulses having a Lorentzian temporal shape. Similar features have been previously observed [D. C. Pace et al., Phys. Plasmas 15, 122304 (2008)] in a linear magnetized device under conditions in which cross-field pressure gradients are present. The reported observation of such features within the turbulent environment of a toroidal confinement device provides support for the conjecture that the underlying processes are a general feature of pressure gradients. Also presented is the magnetic field strength dependence of the pulse widths and the waiting time distribution between pulses
Comparisons of Medical Student Knowledge Regarding Life-Threatening CT Images Before and After Clinical Experience
Introduction. Currently, no national standard exists for educatingmedical students regarding radiography or formal research indicatingthe level of improvement regarding computed tomography(CT) interpretation of medical students during clinical rotations.
Methods. Students were evaluated based on their response totwenty-two open-ended questions regarding diagnosis and treatmentof eleven de-identified CT images of life-threatening injuries.The number of incorrect answers was compared withcorrect or partially correct answers between students startingthird-year clinical rotations and those starting their fourth year.
Results. Survey results were collected from 65 of 65 (100%) beginningthird-year students and 9 of 60 (15%) beginning fourthyearstudents. Students in their fourth-year had less incorrectanswers compared to third-year students, with five questionsreflecting a statistically significant reduction in incorrect responses.The image with the least incorrect for both groups wasepidural hemorrhage, 33.9% and 18.5% incorrect for third-yearstudents for diagnosis and treatment, respectively, and 11.1%and 0% incorrect for fourth-year students. Outside of this image,the range of incorrect answers for third-year students was75.4% to 100% and 44.4% to 100% for fourth-year students.
Conclusion. Baseline CT knowledge of medical students,regardless of clinical experience, indicated a strong deficit,as more students were incorrect than correct for themajority of CT images. KS J Med 2017;10(3):55-58
Galvanische Abscheidung von Dispersionsschichten und Mikrostrukturen aus Nickel mit AIN-Nanopartikeln zur Verbesserung der mechanischen Eigenschaften
Reentrant superconductivity in superconductor/ferromagnetic-alloy bilayers
We studied the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) like state
establishing due to the proximity effect in superconducting Nb/Cu41Ni59
bilayers. Using a special wedge-type deposition technique, series of 20-35
samples could be fabricated by magnetron sputtering during one run. The layer
thickness of only a few nanometers, the composition of the alloy, and the
quality of interfaces were controlled by Rutherford backscattering
spectrometry, high resolution transmission electron microscopy, and Auger
spectroscopy. The magnetic properties of the ferromagnetic alloy layer were
characterized with superconducting quantum interference device (SQUID)
magnetometry. These studies yield precise information about the thickness, and
demonstrate the homogeneity of the alloy composition and magnetic properties
along the sample series. The dependencies of the critical temperature on the Nb
and Cu41Ni59 layer thickness, Tc(dS) and Tc(dF), were investigated for constant
thickness dF of the magnetic alloy layer and dS of the superconducting layer,
respectively. All types of non-monotonic behaviors of Tc versus dF predicted by
the theory could be realized experimentally: from reentrant superconducting
behavior with a broad extinction region to a slight suppression of
superconductivity with a shallow minimum. Even a double extinction of
superconductivity was observed, giving evidence for the multiple reentrant
behavior predicted by theory. All critical temperature curves were fitted with
suitable sets of parameters. Then, Tc(dF) diagrams of a hypothetical F/S/F
spin-switch core structure were calculated using these parameters. Finally,
superconducting spin-switch fabrication issues are discussed in detail in view
of the achieved results.Comment: 34 pages, 9 figure
- …