6,552 research outputs found

    Laser communication system for controlling several functions at a location remote to the laser

    Get PDF
    A multichannel laser remote control system is described. The system is used in areas where radio frequency, acoustic, and hardware control systems are unsatisfactory or prohibited and where line of sight is unobstructed. A modulated continuous wave helium-neon laser is used as the transmitter and a 360 degree light collector serves as the antenna at the receiver

    Cut loci and conjugate loci on Liouville surfaces

    Get PDF
    In the earlier paper (Itoh and Kiyohara, Manuscr Math 114:247–264, 2004), we showed that the cut locus of a general point on two-dimensional ellipsoid is a segment of a curvature line and proved "Jacobi’s last geometric statement" on the singularities of the conjugate locus. In the present paper,we showthat a wider class of Liouville surfaces possess such simple cut loci and conjugate loci. The results include the determination of cut loci and the set of poles on two-sheeted hyperboloids and elliptic paraboloids

    Effects of footwear variations on three-dimensional kinematics and tibial accelerations of specific movements in American football

    Get PDF
    American football is associated with a high rate of non-contact chronic injuries. Players are able to select from both high and low cut footwear. The aim of the current investigation was to examine the influence of high and low cut American football specific footwear on tibial accelerations and three-dimensional (3D) kinematics during three sport specific movements. Twelve male American football players performed three movements, run, cut and vertical jump whilst wearing both low and high cut footwear. 3D kinematics of the lower extremities were measured using an eight-camera motion analysis system alongside tibial acceleration parameters which were obtained using a shank mounted accelerometer. Tibial acceleration and 3D kinematic differences between the different footwear were examined using either repeated measures or Friedman’s ANOVA. Tibial accelerations were significantly greater in the low cut footwear in comparison to the high cut footwear for the run and cut movements. In addition, peak ankle eversion and tibial internal rotation parameters were shown to be significantly greater in the low cut footwear in the running and cutting movement conditions. The current study indicates that the utilization of low cut American football footwear for training/performance may place American footballers at increased risk from chronic injuries

    Neutron capture rates and r-process nucleosynthesis

    Full text link
    Simulations of r-process nucleosynthesis require nuclear physics information for thousands of neutron-rich nuclear species from the line of stability to the neutron drip line. While arguably the most important pieces of nuclear data for the r-process are the masses and beta decay rates, individual neutron capture rates can also be of key importance in setting the final r-process abundance pattern. Here we consider the influence of neutron capture rates in forming the A~80 and rare earth peaks.Comment: 10 pages, 5 figures, appears in the Proceedings of the 14th International Symposium on Capture Gamma-Ray Spectroscopy and Related Topic

    S-band omnidirectional antenna for the SERT-C satellite

    Get PDF
    The program to design an S-band omnidirectional antenna system for the SERT-C spacecraft is discussed. The program involved the tasks of antenna analyses by computer techniques, scale model radiation pattern measurements of a number of antenna systems, full-scale RF measurements, and the recommended design, including detailed drawings. A number of antenna elements were considered: the cavity-backed spiral, quadrifilar helix, and crossed-dipoles were chosen for in-depth studies. The final design consisted of a two-element array of cavity-backed spirals mounted on opposite sides of spacecraft and fed in-phase through a hybrid junction. This antenna system meets the coverage requirement of having a gain of at least minus 10 dBi over 50 percent of a 4 pi steradian sphere with the solar panels in operation. This coverage level is increased if the ground station has the capability to change polarization

    Patent Institutions: Shifting Interactions Between Legal Actors

    Get PDF
    This contribution to the Research Handbook on Economics of Intellectual Property Rights (Vol. 1 Theory) addresses interactions between the principal legal institutions of the U.S. patent system. It considers legal, strategic, and normative perspectives on these interactions as they have evolved over the last 35 years. Early centralization of power by the U.S. Court of Appeals for the Federal Circuit, newly created in 1982, established a regime dominated by the appellate court\u27s bright-line rules. More recently, aggressive Supreme Court and Congressional intervention have respectively reinvigorated patent law standards and led to significant devolution of power to inferior tribunals, including newly created tribunals like the USPTO\u27s Patent Trial and Appeals Board. This new era in institutional interaction creates a host of fresh empirical and normative research questions for scholars. The contribution concludes by outlining a research agenda

    Small Leaf Mid-Rib Xylem Related to Leaf Freeze Tolerance Trait in Bahia (\u3cem\u3ePaspalum Notatum\u3c/em\u3e Flugge) Grass Lines

    Get PDF
    Controlled freeze (-60o C) trials of 31 bahiagrass selections from a breeding program for cold tolerance by Blount et al. (2001) showed diverse genotype Leaf Tissue Cold Damage (LTCD). Breman et al. (2003) defined LTCD on a rating scale (1 = no damage to 9 = 100% leaf damage). Unique midrib damage was observed as part of LTCD in bahiagrass under transpiration stress after a freeze trial. Small xylem conduit diameter and area has been strongly correlated with reduced cavitation caused by freeze thaw cycles which maintain leaf tissue in evergreen temperate woody plants; further shown in twelve woody species by Davis et al. (1999). Air bubbles in vessel ice columns prevent normal refill and function upon thawing. The purpose of this study was to test whether genotype xylem diameter and area could be used to predict LTCD

    Delineation of Emitter-Collector Shorts in Bipolar Test Structures by Voltage Contrast Scanning Electron Microscopy

    Get PDF
    In examining emitter-collector shorts and their relationship to structural defects, we desire a nondestructive method for locating the short-circuited devices in large test arrays. Voltage contrast scanning electron microscopy (VC-SEM) and an established electrochemical anodization technique have been used to identify electrically faulty bipolar transistors. Direct comparison of these approaches was achieved by examining the same emitters with each method. The results indicate that VC-SEM may serve as a useful technique for delineating E-C shorts because of its nondestructive and purely electrical nature. In our qualitative investigation, the sensitivity and voltage resolution available by VC-SEM were not sufficient to differentiate device leakage levels as is often possible with anodization. Such information may, however, be obtainable by utilizing image subtraction and more sophisticated detector systems. Transmission electron microscopy of the transistor structures revealed dislocations in many short-circuited emitters and occasionally in unshorted devices. This confirmed prior observations that crystallographic defects in silicon devices may sometimes be, but are not always, electrically active. Deleterious effects may depend on factors such as junction penetration and dopant-defect interactions

    Evidence for hard chiral logarithms in quenched lattice QCD

    Get PDF
    We present the first direct evidence that quenched QCD differs from full QCD in the chiral (mq0m_q \rightarrow 0) limit, as predicted by chiral perturbation theory, from our quenched lattice QCD simulations at β=6/g2=6.0\beta = 6/g^2 = 6.0. We measured the spectrum of light hadrons on 163×6416^3 \times 64, 243×6424^3 \times 64 and 323×6432^3 \times 64, using staggered quarks of masses mq=0.01m_q=0.01, mq=0.005m_q=0.005 and mq=0.0025m_q=0.0025. The pion masses showed clear evidence for logarithmic violations of the PCAC relation mπ2mqm_{\pi}^2 \propto m_q, as predicted by quenched chiral perturbation theory. The dependence on spatial lattice volume precludes this being a finite size effect. No evidence was seen for such chiral logarithms in the behaviour of the chiral condensate ψˉψ\langle\bar{\psi}\psi\rangle.Comment: 10 pages, 4 figures, uuencoded compressed postscript fil
    corecore