14,415 research outputs found
Rapid billet loader aids extrusion of refractory metals
A combination gravity and manually powered rapid billet loader reduces the time required for transferring hot metal billets from a heating furnace to an extrusion press. Positioned between the furnace and extrusion press, this loader is a simple slide-delivery device
Predicted band structures of III-V semiconductors in wurtzite phase
While non-nitride III-V semiconductors typically have a zincblende structure,
they may also form wurtzite crystals under pressure or when grown as
nanowhiskers. This makes electronic structure calculation difficult since the
band structures of wurtzite III-V semiconductors are poorly characterized. We
have calculated the electronic band structure for nine III-V semiconductors in
the wurtzite phase using transferable empirical pseudopotentials including
spin-orbit coupling. We find that all the materials have direct gaps. Our
results differ significantly from earlier {\it ab initio} calculations, and
where experimental results are available (InP, InAs and GaAs) our calculated
band gaps are in good agreement. We tabulate energies, effective masses, and
linear and cubic Dresselhaus zero-field spin-splitting coefficients for the
zone-center states. The large zero-field spin-splitting coefficients we find
may lead to new functionalities for designing devices that manipulate spin
degrees of freedom
Design and Development of the Space Shuttle Tail Service Masts
The successful launch of a space shuttle vehicle depends on the proper operation of two tail service masts (TSMs). Reliable TSM operation is assured through a comprehensive design, development, and testing program. The results of the concept verification test (CVT) and the resulting impact on prototype TSM design are presented. The design criteria are outlined, and the proposed prototype TSM tests are described
Balance sheet : most important farm financial management tool
"2/82/5M."This circular shows you how to prepare a balance sheet and how to use it in making financial decisions. A balance sheet is the single most important document you use in financing your farm. The balance sheet is an essential document when borrowing money, but more importantly, it can help you determine how much progress you are making on the farm. The balance sheet also can tell you ahead of time when financial problems are likely to occur.Your financial tool kit -- Balance sheet; your most important financial tool -- Organization of the balance sheet -- When to prepare a balance sheet -- How to prepare the balance sheet -- Example balance sheet -- Preparing a balance sheet -- What the balance sheet shows -- Using the balance sheet in making decision
Nonlinear evolution of surface morphology in InAs/AlAs superlattices via surface diffusion
Continuum simulations of self-organized lateral compositional modulation
growth in InAs/AlAs short-period superlattices on InP substrate are presented.
Results of the simulations correspond quantitatively to the results of
synchrotron x-ray diffraction experiments. The time evolution of the
compositional modulation during epitaxial growth can be explained only
including a nonlinear dependence of the elastic energy of the growing epitaxial
layer on its thickness. From the fit of the experimental data to the growth
simulations we have determined the parameters of this nonlinear dependence. It
was found that the modulation amplitude don't depend on the values of the
surface diffusion constants of particular elements.Comment: 4 pages, 3 figures, published in Phys. Rev. Lett.
http://link.aps.org/abstract/PRL/v96/e13610
Impact of ultrafast electronic damage in single particle x-ray imaging experiments
In single particle coherent x-ray diffraction imaging experiments, performed
at x-ray free-electron lasers (XFELs), samples are exposed to intense x-ray
pulses to obtain single-shot diffraction patterns. The high intensity induces
electronic dynamics on the femtosecond time scale in the system, which can
reduce the contrast of the obtained diffraction patterns and adds an isotropic
background. We quantify the degradation of the diffraction pattern from
ultrafast electronic damage by performing simulations on a biological sample
exposed to x-ray pulses with different parameters. We find that the contrast is
substantially reduced and the background is considerably strong only if almost
all electrons are removed from their parent atoms. This happens at fluences of
at least one order of magnitude larger than provided at currently available
XFEL sources.Comment: 15 pages, 3 figures submitted to PR
Health and Medical Researcher Publishing Patterns and How Libraries Support Them
Changing business models in scholarly publishing means that researchers have increased choices as to where to submit their articles. Choices are made on the basis of perceived quality of the journal, the speed of publishing, and how close a match there is between the journal scope and the article topic. Additionally, there is an increasing concern as to whether the journals are predatory. This paper reports on a study which sought to understand how health researchers go about selecting where to publish and the support that they receive in this regard from librarians and related staff. The research confirms that knowledge of a specific journal is still the predominant factor for researchers and that they prefer to rely on their own judgment. Librarians are providing the tools such as databases and whitelists by which better choices can be made whilst exploring new roles in advising and training researchers. Predatory journals are being selected by some, chiefly as a consequence of a lack of awareness amongst researchers and the need for some to publish swiftly and at low cost
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