696 research outputs found
Modular space station phase B extension preliminary system design. Volume 5: configuration analyses
The initial and growth modular space station configurations are described, and the evolutionary steps arriving at the final configuration are outlined. Supporting tradeoff studies and analyses such as stress, radiation dosage, and micrometeoroid and thermal protection are included
Impact of Short-Range Scattering on the Metallic Transport of Strongly Correlated 2D Holes in GaAs Quantum Wells
Understanding the non-monotonic behavior in the temperature dependent
resistance, R(T), of strongly correlated two-dimensional (2D) carriers in clean
semiconductors has been a central issue in the studies of 2D metallic states
and metal-insulator-transitions. We have studied the transport of high mobility
2D holes in 20nm wide GaAs quantum wells (QWs) with varying short-range
disorder strength by changing the Al fraction x in the Al_xGa_{1-x}As barrier.
Via varying the short range interface roughness and alloy scattering, it is
observed that increasing x suppresses both the strength and characteristic
temperature scale of the 2D metallicity, pointing to the distinct role of
short-range versus long-range disorder in the 2D metallic transport in this
correlated 2D hole system with interaction parameter r_s~ 20.Comment: accepted for publication in Phys Rev
The elements of a computational infrastructure for social simulation
Applications of simulation modelling in social science domains are varied and increasingly widespread. The effective deployment of simulation models depends on access to diverse datasets, the use of analysis capabilities, the ability to visualize model outcomes and to capture, share and re-use simulations as evidence in research and policy-making. We describe three applications of e-social science that promote social simulation modelling, data management and visualization. An example is outlined in which the three components are brought together in a transport planning context. We discuss opportunities and benefits for the combination of these and other components into an e-infrastructure for social simulation and review recent progress towards the establishment of such an infrastructure
Conversion From Tacrolimus to Belatacept to Prevent the Progression of Chronic Kidney Disease in Pancreas Transplantation: Case Report of Two Patients
Belatacept is a novel immunosuppressive agent that may be used as an alternative to calcineurin inhibitors (CNI) in immunosuppression (IS) regimens. We report two cases of pancreas transplant that were switched from tacrolimus (TAC) to belatacept. Case 1: 38‐year‐old female with pancreas transplant alone maintained on TAC‐based IS regimen whose serum creatinine (SCr) slowly deteriorated from 0.6 mg/dL at baseline to 2.2 mg/dL, 16 months posttransplant. A native kidney biopsy performed showed CNI toxicity. The patient was started on belatacept and TAC was eliminated. Case 2: 49‐year‐old female with simultaneous pancreas–kidney transplant, maintained on TAC‐based regimen where the SCr worsened over an initial 3‐month period from a baseline of 1.0 to 3.0 mg/dL. Belatacept was started and TAC was lowered. Due to persistent graft dysfunction and kidney transplant biopsy still showing changes consistent with CNI toxicity, the TAC was then discontinued. At >1 year postbelatacept and off TAC follow‐up, kidney function as measured by SCr remains stable at 1.0 ± 0.2 mg/dL in both recipients. Neither patient developed rejection following the switch, and pancreas allograft function remains stable in both recipients
Archiving Software Surrogates on the Web for Future Reference
Software has long been established as an essential aspect of the scientific
process in mathematics and other disciplines. However, reliably referencing
software in scientific publications is still challenging for various reasons. A
crucial factor is that software dynamics with temporal versions or states are
difficult to capture over time. We propose to archive and reference surrogates
instead, which can be found on the Web and reflect the actual software to a
remarkable extent. Our study shows that about a half of the webpages of
software are already archived with almost all of them including some kind of
documentation.Comment: TPDL 2016, Hannover, German
Photon-Photon Scattering, Pion Polarizability and Chiral Symmetry
Recent attempts to detect the pion polarizability via analysis of
measurements are examined. The connection
between calculations based on dispersion relations and on chiral perturbation
theory is established by matching the low energy chiral amplitude with that
given by a full dispersive treatment. Using the values for the polarizability
required by chiral symmetry, predicted and experimental cross sections are
shown to be in agreement.Comment: 21 pages(+10 figures available on request), LATEX, UMHEP-38
Thermodynamic aspects of materials' hardness: prediction of novel superhard high-pressure phases
In the present work we have proposed the method that allows one to easily
estimate hardness and bulk modulus of known or hypothetical solid phases from
the data on Gibbs energy of atomization of the elements and corresponding
covalent radii. It has been shown that hardness and bulk moduli of compounds
strongly correlate with their thermodynamic and structural properties. The
proposed method may be used for a large number of compounds with various types
of chemical bonding and structures; moreover, the temperature dependence of
hardness may be calculated, that has been performed for diamond and cubic boron
nitride. The correctness of this approach has been shown for the recently
synthesized superhard diamond-like BC5. It has been predicted that the
hypothetical forms of B2O3, diamond-like boron, BCx and COx, which could be
synthesized at high pressures and temperatures, should have extreme hardness
Bose-Einstein condensation as symmetry breaking in compact curved spacetimes
We examine Bose-Einstein condensation as a form of symmetry breaking in the
specific model of the Einstein static universe. We show that symmetry breaking
never occursin the sense that the chemical potential never reaches its
critical value.This leads us to some statements about spaces of finite volume
in general. In an appendix we clarify the relationship between the standard
statistical mechanical approaches and the field theory method using zeta
functions.Comment: Revtex, 25 pages, 3 figures, uses EPSF.sty. To be published in Phys.
Rev.
Curricular changes and interim posts during Covid-19 : graduates' perspectives
Background
During the COVID-19 pandemic UK medical schools facilitated the early graduation of their final-year medical students to ‘Foundation interim Year 1 (FiY1) doctors’ through amendments made to curricula and final assessment. Such changes gave opportunity for evaluation. This study therefore aimed to explore 1) graduate perspective on the implementation of FiY1 and 2) how changes to course structures have affected self-reported preparedness for work.
Methods
Questionnaire surveys using Likert scale and free-text responses (n = 45), and semi-structured interviews (n = 7) were conducted with FiY1s from two UK medical schools contrasting in the amendments made to course structures. Data were analysed using quantitative methods and thematic analysis; 44% (n = 20) of respondents believed that governing health bodies had not communicated sufficiently prior to starting work.
Results
Graduates who had sat modified practical and written examinations reported ‘legitimacy’ and feeling more prepared compared to having not sat examinations (practical 100%, n = 17; written 88.3%, n = 15). Graduates from both schools agreed that carrying out assistantships as originally scheduled would have made them feel more prepared (91.1%, n = 41).
Conclusions
The implementation of FiY1 was largely well received by graduates yet assistantship programmes may fulfil a similar role in normal times. Medical schools and governing bodies must ensure effective communication channels exist with students in order to better prepare them for their first posts, especially in times of crisis. Additionally, final examinations contribute to feelings of preparedness for work and instil a sense of legitimacy, a finding which is relevant to working within the current programmatic assessment structure
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