4,490 research outputs found
High efficiency deterministic Josephson Vortex Ratchet
We investigate experimentally a Josephson vortex ratchet -- a fluxon in an
asymmetric periodic potential driven by a deterministic force with zero time
average. The highly asymmetric periodic potential is created in an underdamped
annular long Josephson junction by means of a current injector providing
efficiency of the device up to 91%. We measured the ratchet effect for driving
forces with different spectral content. For monochromatic high-frequency drive
the rectified voltage becomes quantized. At high driving frequencies we also
observe chaos, sub-harmonic dynamics and voltage reversal due to the inertial
mass of a fluxon.Comment: accepted by PRL. To see status click on
http://134.2.74.170:88/cnt/cond-mat_0506754.htm
Heads-Up Display with Virtual Precision Approach Path Indicator as Implemented in a Real-Time Piloted Lifting-Body Simulation
This document describes the heads-up display (HUD) used in a piloted lifting-body entry, approach and landing simulation developed for the simulator facilities of the Simulation Development and Analysis Branch (SDAB) at NASA Langley Research Center. The HUD symbology originated with the piloted simulation evaluations of the HL-20 lifting body concept conducted in 1989 at NASA Langley. The original symbology was roughly based on Shuttle HUD symbology, as interpreted by Langley researchers. This document focuses on the addition of the precision approach path indicator (PAPI) lights to the HUD overlay
Correlation between the reliability of HEMT devices and that of a combined oscillator-amplifier
We evaluate an oscillator-amplifier MMIC submitted to high-temperature operating life time tests. To relate adequately these results with individual components’ results, it is important to realise that failure mechanisms in non-linear MMICs are governed by the maximally instantaneous voltages/currents and hence that comparisons should be conducted at equal instantaneous conditions
Possible role of extracellularly released phagocytic proteinases in the coagulation disorder during liver transplantation
Orthotopic liver transplantation is frequently associated with a complex coagulation disorder, influencing the outcome of the procedure. In this respect, disseminated intravascular coagulation (DIC) had been suggested to be of causative importance for bleeding complications after reperfusion of the liver graft. In 10 consecutive patients undergoing orthotopic liver transplantations, we studied the occurrence of two phagocyte proteinases of different origin in the graft liver perfus-ate and in systemic blood during the operation, as well as their effects on hemostasis. As compared with plasma samples taken at the end of the anhepatic phase, highly significant increases of cathepsin B and thrombin-anti-thrombin III complexes (TAT), as well as highly significant decreases in antithrombin III, protein C, and C1-inhibitor were observed in graft liver perfusate. Von Willebrand factor and fibrinogen were slightly decreased, whereas the elastase-alpha1 proteinase inhibitor complexes (EPI) were elevated. In plasma the activity of cathepsin B remained unchanged during the prereperfusion phases, but immediately after revascularization of the graft this cysteine proteinase increased. The EPI showed a gradual increase in plasma during the preanhepatic and anhepatic phases but a more pronounced increase in the reperfusion phase. In parallel with the rise in these two proteinases TAT increased and the activities of antithrombin III and C1-inhibitor in plasma decreased after reperfusion. At 12 hr after revascularization plasma levels of TAT, antithrombin III, and C1-inhibitor had returned to the prereperfusion ranges, whereas cathepsin B and EPI were significantly above the baseline levels. These observations are consistent with the hypothesis that extracellularly released lysosomal proteinases may play a role in the development of a DIC-like constellation, including thrombin formation after revascularization of the liver graft. For the first time we could prove the occurrence of phagocyte proteinases in graft liver perfusate and evaluate the importance of these proteinases for the understanding of the pathophysiology leading to bleeding complications in patients undergoing orthotopic liver transplantation
Xenogeneic, extracorporeal liver perfusion in primates improves the ratio of branched-chain amino acids to aromatic amino acids (Fischer's ratio)
In fulminant hepatic failure (FHF), the development of hepatic encephalopathy is associated with grossly abnormal concentrations of plasma amino acids (PAA). Normalization of the ratio of branched-chain amino acids to aromatic amino acids (Fischer's ratio) correlates with clinical improvement. This study evaluated changes in PAA metabolism during 4 h of isolated, normothermic extracorporeal liver perfusion using a newly designed system containing human blood and a rhesus monkey liver. Bile and urea production were within the physiological range. Release of the transaminases AST, ALT and LDH were minimal. The ratio of branched (valine, leucine, isoleucine) to aromatic (tyrosine, phenylalanine) amino acids increased significantly. These results indicate that a xenogeneic extracorporeal liver perfusion system is capable of significantly increasing Fischer's ratio and may play a role in treating and bridging patients in FHF in the future
Synthesis for Polynomial Lasso Programs
We present a method for the synthesis of polynomial lasso programs. These
programs consist of a program stem, a set of transitions, and an exit
condition, all in the form of algebraic assertions (conjunctions of polynomial
equalities). Central to this approach is the discovery of non-linear
(algebraic) loop invariants. We extend Sankaranarayanan, Sipma, and Manna's
template-based approach and prove a completeness criterion. We perform program
synthesis by generating a constraint whose solution is a synthesized program
together with a loop invariant that proves the program's correctness. This
constraint is non-linear and is passed to an SMT solver. Moreover, we can
enforce the termination of the synthesized program with the support of test
cases.Comment: Paper at VMCAI'14, including appendi
On the formation/dissolution of equilibrium droplets
We consider liquid-vapor systems in finite volume at parameter
values corresponding to phase coexistence and study droplet formation due to a
fixed excess of particles above the ambient gas density. We identify
a dimensionless parameter and a
\textrm{universal} value \Deltac=\Deltac(d), and show that a droplet of the
dense phase occurs whenever \Delta>\Deltac, while, for \Delta<\Deltac, the
excess is entirely absorbed into the gaseous background. When the droplet first
forms, it comprises a non-trivial, \textrm{universal} fraction of excess
particles. Similar reasoning applies to generic two-phase systems at phase
coexistence including solid/gas--where the ``droplet'' is crystalline--and
polymorphic systems. A sketch of a rigorous proof for the 2D Ising lattice gas
is presented; generalizations are discussed heuristically.Comment: An announcement of a forthcoming rigorous work on the 2D Ising model;
to appear in Europhys. Let
Rendimento de grãos de milho safrinha em diferentes populações de espécies forrageiras.
bitstream/item/65390/1/29899.pdfOrganizado por Gessi Ceccon e Luiz Alberto Staut
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