15,108 research outputs found
Niobium hyperfine structure in crystal calcium tungstate
A study of the niobium hyperfine structure in single crystal calcium tungstate was made by the combination of the technique of electron paramagnetic resonance and electron nuclear double resonance (EPR/ENDOR). The microwave frequency was about 9.4 GHz and the radio frequency from 20MHz to 70 MHz. The rare earth ions Nd(3+), U(3+), or Tm(3+) were added as the charge compensator for Nb(5+). To create niobium paramagnetic centers, the sample was irradiated at 77 deg K with a 10 thousand curie Co-60 gamma source for 1 to 2 hours at a dose rate of 200 K rads per hour and then transferred quickly into the cavity. In a general direction of magnetic field, the spectra showed 4 sets of 10 main lines corresponding to 4 nonequivalent sites of niobium with I = 9/2. These 4 sets of lines coalesced into 2 sets of 10 in the ab-plane and into a single set of 10 along the c-axis. This symmetry suggested that the tungsten ions are substituted by the niobium ions in the crystal
Steady, oscillatory, and unsteady subsonic Aerodynamics, production version 1.1 (SOUSSA-P1.1). Volume 2: User/programmer manual
A user/programmer manual for the computer program SOUSSA P 1.1 is presented. The program was designed to provide accurate and efficient evaluation of steady and unsteady loads on aircraft having arbitrary shapes and motions, including structural deformations. These design goals were in part achieved through the incorporation of the data handling capabilities of the SPAR finite element Structural Analysis computer program. As a further result, SOUSSA P possesses an extensive checkpoint/ restart facility. The programmer's portion of this manual includes overlay/subroutine hierarchy, logical flow of control, definition of SOUSSA P 1.1 FORTRAN variables, and definition of SOUSSA P 1.1 subroutines. Purpose of the SOUSSA P 1.1 modules, input data to the program, output of the program, hardware/software requirements, error detection and reporting capabilities, job control statements, a summary of the procedure for running the program and two test cases including input and output and listings are described in the user oriented portion of the manual
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Mobile Paving System (MPS): A New Large Scale Freeform Fabrication Method
In the last decade, significant opportunities for automation have been identified in the area of
construction. Soaring labor and material costs have driven multiple research efforts in
construction automation. In this paper, we present a novel means for construction automation
that involves the fusion of the rapid prototyping, controls and mechatronics technologies. The
resultant autonomous construction mechanism has been designed for commercial applications.
Mobile Paving System (MPS) is a new freeform fabrication process which is capable of rapidly
producing variable profiles such as curbs and sidewalks out of materials like cement and asphalt.
Path generation and guidance of the construction operation is controlled by a mobile robot. This
article presents an overview of research and development efforts that are aimed at establishing
the feasibility and the potential of the process.Mechanical Engineerin
Reaching Approximate Byzantine Consensus with Multi-hop Communication
We address the problem of reaching consensus in the presence of Byzantine
faults. In particular, we are interested in investigating the impact of
messages relay on the network connectivity for a correct iterative approximate
Byzantine consensus algorithm to exist. The network is modeled by a simple
directed graph. We assume a node can send messages to another node that is up
to hops away via forwarding by the intermediate nodes on the routes, where
is a natural number. We characterize the necessary and
sufficient topological conditions on the network structure. The tight
conditions we found are consistent with the tight conditions identified for
, where only local communication is allowed, and are strictly weaker for
. Let denote the length of a longest path in the given network. For
and undirected graphs, our conditions hold if and only if and the node-connectivity of the given graph is at least , where
is the total number of nodes and is the maximal number of Byzantine
nodes; and for and directed graphs, our conditions is equivalent to
the tight condition found for exact Byzantine consensus.
Our sufficiency is shown by constructing a correct algorithm, wherein the
trim function is constructed based on investigating a newly introduced minimal
messages cover property. The trim function proposed also works over
multi-graphs.Comment: 24 pages, 1 figure. arXiv admin note: text overlap with
arXiv:1203.188
Response Detection of Castrate-Resistant Prostate Cancer to Clinically Utilised and Novel Treatments by Monitoring Phospholipid Metabolism
The authors gratefully acknowledge funding from Grampian NHS Endowment. The use of Professor Zanda’s and Jaspar’s NMR equipment and Russell Gray’s assistance are also gratefully acknowledged.Peer reviewedPublisher PD
On the Boundary Entropy of One-dimensional Quantum Systems at Low Temperature
The boundary beta-function generates the renormalization group acting on the
universality classes of one-dimensional quantum systems with boundary which are
critical in the bulk but not critical at the boundary. We prove a gradient
formula for the boundary beta-function, expressing it as the gradient of the
boundary entropy s at fixed non-zero temperature. The gradient formula implies
that s decreases under renormalization except at critical points (where it
stays constant). At a critical point, the number exp(s) is the ``ground-state
degeneracy,'' g, of Affleck and Ludwig, so we have proved their long-standing
conjecture that g decreases under renormalization, from critical point to
critical point. The gradient formula also implies that s decreases with
temperature except at critical points, where it is independent of temperature.
The boundary thermodynamic energy u then also decreases with temperature. It
remains open whether the boundary entropy of a 1-d quantum system is always
bounded below. If s is bounded below, then u is also bounded below.Comment: 12 pages, Latex, 1 eps-figure; v2: some expository material added, a
slightly more condensed version of the paper is publihed in Phys. Rev. Let
Functional modulation of the transient outward current Ito by KCNE beta-subunits and regional distribution in human non-failing and failing hearts
Objectives: The function of Kv4.3 (KCND3) channels, which underlie the transient outward current I,, in human heart, can be modulated by several accessory subunits such as KChIP2 and KCNE1-KCNE5. Here we aimed to determine the regional expression of Kv4.3, KChIP2, and KCNE mRNAs in non-failing and failing human hearts and to investigate the functional consequences of subunit coexpression in heterologous expression systems.
Methods: We quantified mRNA levels for two Kv4.3 isoforms, Kv4.3-S and Kv4.3-L, and for KChIP2 as well as KCNE1-KCNE5 with real-time RT-PCR. We also studied the effects of KCNEs on Kv4.3 + KChIP2 current characteristics in CHO cells with the whole-cell voltage-clamp method.
Results: In non-failing hearts, low expression was found for KCNE1, KCNE3, and KCNE5, three times higher expression for KCNE2, and 60 times higher for KCNE4. Transmural gradients were detected only for KChIP2 in left and right ventricles. Compared to non-failing tissue, failing hearts showed higher expression of Kv4.3-L and KCNE1 and lower of Kv4.3-S, KChIP2, KCNE4, and KCNE5. In CHO cells, Kv4.3 + KChIP2 currents were differentially modified by co-expressed KCNEs: time constants of inactivation were shorter with KCNE1 and KCNE3-5 while time-to-peak was decreased, and V-0.5 of steady-state inactivation was shifted to more negative potentials by all KCNE subunits. Importantly, KCNE2 induced a unique and prominent 'overshoot' of peak current during recovery from inactivation similar to that described for human I-to while other KCNE subunits induced little (KCNE4,5) or no overshoot.
Conclusions: All KCNEs are expressed in the human heart at the transcript level. Compared to It. in native human myocytes, none of the combination of KChIP2 and KCNE produced an ideal congruency in current characteristics, suggesting that additional factors contribute to the regulation of the native I-to channel
Jet array impingement flow distributions and heat transfer characteristics. Effects of initial crossflow and nonuniform array geometry
Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. The configurations considered are intended to model those of interest in current and contemplated gas turbine airfoil midchord cooling applications. The effects of an initial crossflow which approaches the array through an upstream extension of the channel are considered. Flow distributions as well as heat transfer coefficients and adiabatic wall temperatures resolved to one streamwise hole spacing were measured as a function of the initial crossflow rate and temperature relative to the jet flow rate and temperature. Both Nusselt number profiles and dimensionless adiabatic wall temperature (effectiveness) profiles are presented and discussed. Special test results which show a significant reduction of jet orifice discharge coefficients owing to the effect of a confined crossflow are also presented, along with a flow distribution model which incorporates those effects. A nonuniform array flow distribution model is developed and validated
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