3,387 research outputs found
A numerical simulation of the NFAC (National Full-scale Aerodynamics Complex) open-return wind tunnel inlet flow
The flow into an open return wind tunnel inlet was simulated using Euler equations. An explicit predictor-corrector method was employed to solve the system. The calculation is time-accurate and was performed to achieve a steady-state solution. The predictions are in reasonable agreement with the experimental data. Wall pressures are accurately predicted except in a region of recirculating flow. Flow-field surveys agree qualitatively with laser velocimeter measurements. The method can be used in the design process for open return wind tunnels
Evolution of Magnetism in Single-Crystal Honeycomb Iridates
We report the successful synthesis of single-crystals of the layered iridate,
(NaLi)IrO, , and a thorough study of
its structural, magnetic, thermal and transport properties. The new compound
allows a controlled interpolation between NaIrO and LiIrO,
while maintaing the novel quantum magnetism of the honeycomb Ir planes.
The measured phase diagram demonstrates a dramatic suppression of the N\'eel
temperature, , at intermediate suggesting that the magnetic order in
NaIrO and LiIrO are distinct, and that at , the
compound is close to a magnetically disordered phase that has been sought after
in NaIrO and LiIrO. By analyzing our magnetic data with a
simple theoretical model we also show that the trigonal splitting, on the
Ir ions changes sign from NaIrO and LiIrO, and the
honeycomb iridates are in the strong spin-orbit coupling regime, controlled by
\jeff=1/2 moments.Comment: updated version with more dat
Position Paper From the Association of Pathology Chairs: Assessing Autopsy Competency in Pathology Residency Training
Declining numbers of hospital autopsies performed in US pathology residency training programs and perceived declining practice of autopsy by many pathologists has caused stakeholder organizations to reassess the role of autopsy training in pathology residency. A working group convened by the stakeholder organizations has delivered the results of a detailed study of current practice of autopsy education in US pathology programs, along with recommendations for the future of autopsy education. Accepting the report of the Working Group, the Association of Pathology Chairs here publishes its position paper on the proposed recommendations
Quantum Aspects of Black Hole Entropy
This survey intends to cover recent approaches to black hole entropy which
attempt to go beyond the standard semiclassical perspective. Quantum
corrections to the semiclassical Bekenstein-Hawking area law for black hole
entropy, obtained within the quantum geometry framework, are treated in some
detail. Their ramification for the holographic entropy bound for bounded
stationary spacetimes is discussed. Four dimensional supersymmetric extremal
black holes in string-based N=2 supergravity are also discussed, albeit more
briefly.Comment: 13 Pages Revtex with 3 eps figures; based on plenary talk given at
the International Conference on Gravitation and Cosmology, Kharagpur, India,
January, 2000 One reference adde
Position Paper From the Association of Pathology Chairs: Surgical Pathology Residency Training
Training in surgical pathology specimen dissection and microscopic diagnosis is an integral part of pathology residency training, as surgical pathology is one of the defining activities of most pathologists. The Accreditation Council for Graduate Medical Education and the American Board of Pathology policies delineate guidelines and requirements for residency training. Both the ACGME and ABP require that residents are ready for “independent practice� upon completion of training (ACGME) and for board eligibility (ABP). This position paper, developed through a consensus process involving the Association of Pathology Chairs, including the Program Directors and Graduate Medical Education committee, expands on these guidelines and the importance of gross dissection as a part of training
Influence of ion implantation on the magnetic and transport properties of manganite films
We have used oxygen ions irradiation to generate controlled structural
disorder in thin manganite films. Conductive atomic force microscopy CAFM),
transport and magnetic measurements were performed to analyze the influence of
the implantation process in the physical properties of the films. CAFM images
show regions with different conductivity values, probably due to the random
distribution of point defect or inhomogeneous changes of the local Mn3+/4+
ratio to reduce lattice strains of the irradiated areas. The transport and
magnetic properties of these systems are interpreted in this context.
Metal-insulator transition can be described in the frame of a percolative
model. Disorder increases the distance between conducting regions, lowering the
observed TMI. Point defect disorder increases localization of the carriers due
to increased disorder and locally enhanced strain field. Remarkably, even with
the inhomogeneous nature of the samples, no sign of low field magnetoresistance
was found. Point defect disorder decreases the system magnetization but doesn t
seem to change the magnetic transition temperature. As a consequence, an
important decoupling between the magnetic and the metal-insulator transition is
found for ion irradiated films as opposed to the classical double exchange
model scenario.Comment: 27 pages, 11 Figure
Propagation effects handbook for satellite systems design. A summary of propagation impairments on 10 to 100 GHz satellite links with techniques for system design
This Propagation Handbook provides satellite system engineers with a concise summary of the major propagation effects experienced on Earth-space paths in the 10 to 100 GHz frequency range. The dominant effect, attenuation due to rain, is dealt with in some detail, in terms of both experimental data from measurements made in the U.S. and Canada, and the mathematical and conceptual models devised to explain the data. In order to make the Handbook readily usable to many engineers, it has been arranged in two parts. Chapters 2-5 comprise the descriptive part. They deal in some detail with rain systems, rain and attenuation models, depolarization and experimental data. Chapters 6 and 7 make up the design part of the Handbook and may be used almost independently of the earlier chapters. In Chapter 6, the design techniques recommended for predicting propagation effects in Earth-space communications systems are presented. Chapter 7 addresses the questions of where in the system design process the effects of propagation should be considered, and what precautions should be taken when applying the propagation results
A new holographic entropy bound from quantum geometry
A new entropy bound, tighter than the standard holographic bound due to
Bekenstein, is derived for spacetimes with non-rotating isolated horizons, from
the quantum geometry approach in which the horizon is described by the boundary
degrees of freedom of a three dimensional Chern Simons theory.Comment: 4 pages revtex, no figures; some additions made in text, leading to
stronger results; minor changes in the list of reference
Epitaxial Stabilization of Ultrathin Films of Rare-Earth Nickelates
We report on the synthesis of ultrathin films of highly distorted EuNiO3
(ENO) grown by interrupted pulse laser epitaxy on YAlO3 (YAO) substrates.
Through mapping the phase space of nickelate thin film epitaxy, the optimal
growth temperatures were found to scale linearly with the Goldschmidt tolerance
factor. Considering the gibbs energy of the expanding film, this empirical
trend is discussed in terms of epitaxial stabilization and the escalation of
the lattice energy due to lattice distortions and decreasing symmetry. These
findings are fundamental to other complex oxide perovskites, and provide a
route to the synthesis of other perovskite structures in ultrathin-film form.Comment: 7 pages, 3 figure
Building A Winning NFL Roster: Best Practices For Sustained Success
The purpose of this capstone is to identify and analyze the factors that contribute to team success in the National Football League through a review of relevant literature, a survey of league personnel, and firsthand experience as a football administrator. This project first studies quantitative data regarding player acquisition, specifically the data behind the NFL entry draft. Next, the current literature regarding off the field processes such as leadership, organizational culture and engagement were reviewed and finally, a two-step Delphi method survey was distributed to a panel of current league professionals. This paper aims to find the most efficient and effective way for teams to acquire players and several ways to optimize that talent based on the best practices researched in organizational culture and leadership
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