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Sample records for electromotive force proportional

  1. EVALUATION OF IMPRESSED ELECTROMOTIVE FORCE CATHODIC PROTECTION

    DTIC Science & Technology

    Electromotive couples consisting of 0.064 in. x 24 in. x 24 in. bare 7075-T6 aluminum cathodes and 0.064 in. x 2 in. x 3 in. RC-70 titanium or...such a manner that it opposed the galvanic current. In a series of tests wherein the impressed voltage and current was varied from specimen to specimen

  2. Rethinking Faraday's Law for Teaching Motional Electromotive Force

    ERIC Educational Resources Information Center

    Zuza, Kristina; Guisasola, Jenaro; Michelini, Marisa; Santi, Lorenzo

    2012-01-01

    This study shows physicists' discussions on the meaning of Faraday's law where situations involving extended conductors or moving contact points are particularly troublesome. We raise questions to test students' difficulties in applying Faraday's law in motional electromotive force phenomena. We suggest the benefit of analysing these phenomena…

  3. Rethinking Faraday's Law for Teaching Motional Electromotive Force

    ERIC Educational Resources Information Center

    Zuza, Kristina; Guisasola, Jenaro; Michelini, Marisa; Santi, Lorenzo

    2012-01-01

    This study shows physicists' discussions on the meaning of Faraday's law where situations involving extended conductors or moving contact points are particularly troublesome. We raise questions to test students' difficulties in applying Faraday's law in motional electromotive force phenomena. We suggest the benefit of analysing these phenomena…

  4. Temperature evolution of electromotive force from Pt on yttrium-iron-garnet under ferromagnetic resonance

    SciTech Connect

    Ohshima, Ryo; Emoto, Hiroyuki; Shinjo, Teruya; Ando, Yuichiro; Shiraishi, Masashi

    2015-05-07

    Temperature evolution of electromotive force from Pt due to the inverse spin Hall effect is studied. Pure spin current is injected from yttrium-iron-garnet by using spin pumping technique. The electromotive force from the Pt monotonically decreases with decreasing temperature, and it is showed that there is a deviation between the measured and the calculated electromotive forces.

  5. Electromotive force and huge magnetoresistance in magnetic tunnel junctions.

    PubMed

    Pham, Nam Hai; Ohya, Shinobu; Tanaka, Masaaki; Barnes, Stewart E; Maekawa, Sadamichi

    2009-03-26

    The electromotive force (e.m.f.) predicted by Faraday's law reflects the forces acting on the charge, -e, of an electron moving through a device or circuit, and is proportional to the time derivative of the magnetic field. This conventional e.m.f. is usually absent for stationary circuits and static magnetic fields. There are also forces that act on the spin of an electron; it has been recently predicted that, for circuits that are in part composed of ferromagnetic materials, there arises an e.m.f. of spin origin even for a static magnetic field. This e.m.f. can be attributed to a time-varying magnetization of the host material, such as the motion of magnetic domains in a static magnetic field, and reflects the conversion of magnetic to electrical energy. Here we show that such an e.m.f. can indeed be induced by a static magnetic field in magnetic tunnel junctions containing zinc-blende-structured MnAs quantum nanomagnets. The observed e.m.f. operates on a timescale of approximately 10(2)-10(3) seconds and results from the conversion of the magnetic energy of the superparamagnetic MnAs nanomagnets into electrical energy when these magnets undergo magnetic quantum tunnelling. As a consequence, a huge magnetoresistance of up to 100,000 per cent is observed for certain bias voltages. Our results strongly support the contention that, in magnetic nanostructures, Faraday's law of induction must be generalized to account for forces of purely spin origin. The huge magnetoresistance and e.m.f. may find potential applications in high sensitivity magnetic sensors, as well as in new active devices such as 'spin batteries'.

  6. An Electromotive Force Measurement System for Alloy Fuels

    SciTech Connect

    Changhu Xing; Colby Jensen; Heng Ban; Robert Mariani; J. Rory Kennedy

    2010-11-01

    The development of advanced nuclear fuels requires a better understanding of the transmutation and micro-structural evolution of the materials. Alloy fuels have the advantage of high thermal conductivity and improved characteristics in fuel-cladding chemical reaction. However, information on thermodynamic and thermophysical properties is limited. The objective of this project is to design and build an experimental system to measure the thermodynamic properties of solid materials from which the understanding of their phase change can be determined. The apparatus was used to measure the electromotive force (EMF) of several materials in order to calibrate and test the system. The EMF of chromel was measured from 100°C to 800°C and compared with theoretical values. Additionally, the EMF measurement of Ni-Fe alloy was performed and compared with the Ni-Fe phase diagram. The prototype system is to be modified eventually and used in a radioactive hot-cell in the future.

  7. Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence

    DOE PAGES

    Squire, J.; Bhattacharjee, A.

    2015-11-02

    Here, this article presents a calculation of the mean electromotive force arising from general small-scale magnetohydrodynamical turbulence, within the framework of the second-order correlation approximation. With the goal of improving understanding of the accretion disk dynamo, effects arising through small-scale magnetic fluctuations, velocity gradients, density and turbulence stratification, and rotation, are included. The primary result, which supplements numerical findings, is that an off-diagonal turbulent resistivity due to magnetic fluctuations can produce large-scale dynamo action-the magnetic analog of the "shear-current" effect. In addition, consideration of alpha effects in the stratified regions of disks gives the puzzling result that there is nomore » strong prediction for a sign of alpha, since the effects due to kinetic and magnetic fluctuations, as well as those due to shear and rotation, are each of opposing signs and tend to cancel each other.« less

  8. Probing university students' understanding of electromotive force in electricity

    NASA Astrophysics Data System (ADS)

    Garzón, Isabel; De Cock, Mieke; Zuza, Kristina; van Kampen, Paul; Guisasola, Jenaro

    2014-01-01

    The goal of this study is to identify students' difficulties with learning the concepts of electromotive force (emf) and potential difference in the context of transitory currents and resistive direct-current circuits. To investigate these difficulties, we developed a questionnaire based on an analysis of the theoretical and epistemological framework of physics, which was then administered to first-year engineering and physics students at universities in Spain, Colombia, and Belgium. The results of the study show that student difficulties seem to be strongly linked to the absence of an analysis of the energy balance within the circuit and that most university students do not clearly understand the usefulness of and the difference between the concepts of potential difference and emf.

  9. Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence.

    PubMed

    Squire, J; Bhattacharjee, A

    2015-11-01

    This article presents a calculation of the mean electromotive force arising from general small-scale magnetohydrodynamical turbulence, within the framework of the second-order correlation approximation. With the goal of improving understanding of the accretion disk dynamo, effects arising through small-scale magnetic fluctuations, velocity gradients, density and turbulence stratification, and rotation, are included. The primary result, which supplements numerical findings, is that an off-diagonal turbulent resistivity due to magnetic fluctuations can produce large-scale dynamo action-the magnetic analog of the "shear-current" effect. In addition, consideration of α effects in the stratified regions of disks gives the puzzling result that there is no strong prediction for a sign of α, since the effects due to kinetic and magnetic fluctuations, as well as those due to shear and rotation, are each of opposing signs and tend to cancel each other.

  10. Electromotive force due to magnetohydrodynamic fluctuations in sheared rotating turbulence

    SciTech Connect

    Squire, J.; Bhattacharjee, A.

    2015-11-02

    Here, this article presents a calculation of the mean electromotive force arising from general small-scale magnetohydrodynamical turbulence, within the framework of the second-order correlation approximation. With the goal of improving understanding of the accretion disk dynamo, effects arising through small-scale magnetic fluctuations, velocity gradients, density and turbulence stratification, and rotation, are included. The primary result, which supplements numerical findings, is that an off-diagonal turbulent resistivity due to magnetic fluctuations can produce large-scale dynamo action-the magnetic analog of the "shear-current" effect. In addition, consideration of alpha effects in the stratified regions of disks gives the puzzling result that there is no strong prediction for a sign of alpha, since the effects due to kinetic and magnetic fluctuations, as well as those due to shear and rotation, are each of opposing signs and tend to cancel each other.

  11. THE MEAN ELECTROMOTIVE FORCE RESULTING FROM MAGNETIC BUOYANCY INSTABILITY

    SciTech Connect

    Davies, C. R.; Hughes, D. W. E-mail: d.w.hughes@leeds.ac.uk

    2011-02-01

    Motivated both by considerations of the generation of large-scale astrophysical magnetic fields and by potential problems with mean magnetic field generation by turbulent convection, we investigate the mean electromotive force (emf) resulting from the magnetic buoyancy instability of a rotating layer of stratified magnetic field, considering both unidirectional and sheared fields. We discuss why the traditional decomposition into {alpha} and {beta} effects is inappropriate in this case, and that it is only consideration of the entire mean emf that is meaningful. By considering a weighted average of the unstable linear eigenmodes, and averaging over the horizontal plane, we obtain depth-dependent emfs. For the simplified case of isothermal, ideal MHD, we are able to obtain an analytic expression for the emf; more generally, the emf has to be determined numerically. We calculate how the emf depends on the various parameters of the problem, particularly the rotation rate and the latitude of the magnetic layer.

  12. Control of flexible structure using back electromotive force of motor

    NASA Astrophysics Data System (ADS)

    Matsuda, Khoichi; Hatano, Shinji; Fujii, Hironori

    Wave absorbing control for vibration suppression of flexible space structure is studied. In order to implement control method in a realistic system, it is usually necessary that the signals obtained from sensors are led to actuators through the process of the digital computer programmed under the control law. In this study, a torque motor is used not only as the actuator but also the sensor which detects time differentiation of shaft angle and closes a control loop without using the process of the digital computation. The motor is connected to an electronic circuit which includes the frequency-dependent impedance. The back electromotive force (e.m.f.) of the motor is induced when the shaft of the motor rotates and electric current is generated in the circuit. When the current passes through the motor, it creates control torque for the motor, enabling the suppression of the vibration of a beam without using the digital computer. The control method is confirmed to work well through use of the numerical simulation.

  13. An electromotive force series in a borosilicate glass-forming melt

    NASA Technical Reports Server (NTRS)

    Schreiber, H. D.; Balazs, G. B.; Carpenter, B. E.; Kirkley, J. E.; Minnix, L. M.; Jamison, P. L.

    1984-01-01

    An electromotive force series for redox couples was defined as a function of oxygen fugacity in a borosilicate melt at 1150 C. The resulting order of relative reduction potentials can be used to estimate the amounts of redox species in glass during processing. The electromotive force series in this melt is comparable to those in other silicate glass-forming melts and in aqueous systems but differs in detail because of interaction of the solvents with individual redox couples.

  14. Dember and photo-electromotive-force currents in silicon photoconductive detectors

    NASA Astrophysics Data System (ADS)

    Dikmelik, Yamaç; Davidson, Frederic M.

    2004-09-01

    Dember and photo-electromotive-force (PEMF) currents are investigated in silicon photoconductive detectors both theoretically and experimentally. Dember photocurrents were found to dominate the response of high-purity silicon samples with top-surface electrodes to a moving interference pattern. The use of surface electrodes leads to shadowed regions beneath the electrodes, and Dember photocurrents appear under short-circuit conditions. A single-charge-carrier model of the Dember effect is in good qualitative agreement with experimental results. We also show theoretically that the PEMF effect in silicon is weak compared with other semiconductors because of its relatively high intrinsic conductivity.

  15. Topological electromotive force from domain-wall dynamics in a ferromagnet

    SciTech Connect

    Yang, Shengyuan; Beach, Geoffrey S. D.; Knutson, Carl; Xiao, Di; Zhang, Zhenyu; Tsoi, Maxin; Niu, Qian

    2010-01-01

    We formulate a local gauge-invariant theory for the electromotive force induced by domain-wall dynamics in a ferromagnet. We demonstrate that this emf generation is a real-space topological pumping effect. The integral of the emf over one pumping period is a quantized topological invariant which does not depend on the details of the domain-wall configuration nor on its detailed dynamics. Based on our theory, the full instanta- neous electric potential distribution can be mapped out by standard electrostatic methods. We also provide further details on our recent experiments which confirmed the emf induced by domain-wall dynamics.

  16. The effect of electromotive-force generation on electrical properties of thin samarium sulfide films

    SciTech Connect

    Kaminskii, V. V. Kazanin, M. M.; Solov'ev, S. M.; Sharenkova, N. V.; Volodin, N. M.

    2006-06-15

    Electrical properties of thin SmS polycrystalline films with various values of the lattice constant at T = 300-580 K are studied. Specific features of the temperature dependences of electrical conductivity at T > 450 K are revealed. The effect of generation of the electromotive force with magnitude as large as 1.3 V at T = 440-470 K is observed when the films were subjected to the pressure of a spherical indenter. It is shown that it is possible to transform SmS films into a high-resistivity state (with the difference in the resistivity by three orders of magnitude) by applying an electric field with the strength higher than 100 V/cm. All the results obtained are accounted for using a model of the phenomenon of the electromotive-force generation in SmS under uniform heating of the sample and can also be attributed to the variable valence of samarium ions with respect to the lattice defects.

  17. Electromotive Force Measurements in the Ternary System Bi-In-Zn

    NASA Astrophysics Data System (ADS)

    Knott, Sabine; Li, Zuoan; Wang, C.-H.; Mikula, Adolf

    2010-12-01

    The thermodynamic properties of the ternary Bi-In-Zn system were determined with the electromotive force (EMF) method using a liquid electrolyte. Four different cross sections with constant In/Bi ratios of 1:2, 1:1, 2:1, and 9:1 were applied to measure the thermodynamic properties of the ternary system in the temperature range between the liquidus temperature of the alloys and 973 K (700 °C). Zinc was added in steps of 5 at. pct from 5 to 90 pct. The partial free energies of Zn in liquid Bi-In-Zn alloys were determined as a function of concentration and temperature. The integral Gibbs free energy and the integral enthalpy of the ternary system at 873 K (600 °C) were calculated by Gibbs-Duhem integration. The ternary interaction parameters were evaluated using the Redlich-Kister-Muggianu polynomials.

  18. Fluctuations of the proton-electromotive force across the inner mitochondrial membrane

    NASA Astrophysics Data System (ADS)

    Procopio, Joaquim; Fornés, José A.

    1997-05-01

    The intermembrane mitochondrial space (IMMS) is delimited by the inner and outer mitochondrial membranes and defines a region of molecular dimension where fluctuations of the number of free protons and of transmembrane voltage can give rise to fluctuations in the proton-electromotive force EPMF across the inner mitochondrial membrane (IMM). We have applied the fluctuation-dissipation theorem to an electrical equivalent circuit consisting of a resistor Rm in parallel with a capacitor Cm representing the passive electrical properties of the IMM, in series with another capacitor Cb representing the proton-buffering power of the IMMS fluid. An access resistance Ra was defined as a link between the capacitor Cb and the membrane. Average EPMF fluctuations across the IMM were calculated for different assumptions concerning the intermembrane space dimensions. The calculated average EPMF fluctuations were in the vicinity of 100 mV for relaxation times in the few-microseconds range. The corresponding fluctuational protonic free energy is about 10 kJ/mole, which is comparable to the binding energy for protons in different transporters. This suggests that fluctuations in EPMF can be of relevance in the universe of forces influencing the molecular machinery embedded in the IMM.

  19. Electromotive Force for Solid Oxide Fuel Cells Using Biomass Produced Gas as Fuel

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Yin, Yan-hong; Gao, Cen; Xia, Chang-rong; Meng, Guang-yao

    2006-08-01

    The electromotive force (e.m.f.) of solid oxide fuel cells using biomass produced gas (BPG) as the fuels is calculated at 700-1,200 K using an in-house computer program, based on thermodynamic equilibrium analysis. Tour program also predicts the concentration of oxygen in the fuel chamber as well as the concentration of equilibrium species such as H2, CO, CO2 and CH4. Compared with using hydrogen as a fuel, the e.m.f. for cells using BPG as the fuels is relative low and strongly influenced by carbon deposition. To remove carbon deposition, the optimum amount of H2O to add is determined at various operating temperatures. Further the e.m.f. for cells based on yttria stabilized zirconia and doped ceria as electrolytes are compared. The study reveals that when using BPG as fuel, the depression of e.m.f. for a SOFC using doped ceria as electrolyte is relatively small when compared with that using Yttria stabilized zirconia.

  20. The influence of helical background fields on current helicity and electromotive force of magnetoconvection

    NASA Astrophysics Data System (ADS)

    Rüdiger, G.; Küker, M.

    2016-07-01

    Motivated by the empirical finding that the known hemispheric rules for the current helicity at the solar surface are not strict, we demonstrate the excitation of small-scale current helicity by the influence of large-scale helical magnetic background fields on nonrotating magnetoconvection. This is shown within a quasilinear analytic theory of driven turbulence and by nonlinear simulations of magnetoconvection that the resulting small-scale current helicity has the same sign as the large-scale current helicity, while the ratio of both pseudoscalars is of the order of the magnetic Reynolds number of the convection. The same models do not provide finite values of the small-scale kinetic helicity. On the other hand, a turbulence-induced electromotive force is produced including the diamagnetic pumping term, as well as the eddy diffusivity but, however, no α effect. It has thus been argued that the relations for the simultaneous existence of small-scale current helicity and α effect do not hold for the model of nonrotating magnetoconvection under consideration. Calculations for various values of the magnetic Prandtl number demonstrate that, for the considered diffusivities, the current helicity increases for growing magnetic Reynolds number, which is not true for the velocity of the diamagnetic pumping, which is in agreement with the results of the quasilinear analytical approximation.

  1. University students’ understanding of the electromotive force concept in the context of electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Zuza, Kristina; De Cock, Mieke; van Kampen, Paul; Bollen, Laurens; Guisasola, Jenaro

    2016-11-01

    In this work, we present research on university students’ understanding of the concept of electromotive force (emf). The work presented here is a continuation of previous research by Garzón et al (2014 Am. J. Phys. 82 72-6) in which university students’ understanding of emf in the contexts of transient current and direct current circuits was analyzed. In the work we present here the investigation focuses on electromagnetic induction phenomena. Three open-ended questions from a broader questionnaire were analyzed in depth. We used phenomenography to define categories and detect lines of reasoning and difficulties in conceptual understanding. Very few students showed a good understanding of the emf concept in electromagnetic induction circuits or an ability to distinguish it from potential difference. Although the prevalences of the responses in the different categories are different, we find that the difficulties are the same in the three universities. Standard instruction does not allow most students to analyze unfamiliar contexts where the answer requires a systemic explanatory model.

  2. In-situ detection of growth striations by crystallization electromotive force measurement during Czochralski crystal growth

    NASA Astrophysics Data System (ADS)

    Zhu, Yunzhong; Ma, Decai; Long, Siwei; Tang, Feng; Lin, Shaopeng; Wang, Biao

    2017-10-01

    Growth striations, as macrodefects of crystalline materials, are mainly caused by convection and temperature fluctuations in growth interface. For decades, striations have been widely regarded as an inherent problem. Even in the well-developed Czochralski method, the striation formation process is difficult to inspect in situ. In view of this long-standing issue, after systematically studying the temperature, weight, and output power during crystal growth and numerically modeling the growth process, we found that the regularity of the growth interface electromotive force (GEMF) is related to the distribution of striations. Furthermore, the GEMF quantifies interface fluctuations (711.2 s, 16.6 μm) and thermal hysteresis (107 s), presenting finer details than those provided by a thermocouple and a load cell. In this paper, GEMF is found to be an outstanding choice for monitoring the crystal growth status in real time. As an additional feedback, a new automatic control method could be developed for reducing growth striations and promoting crystal quality.

  3. The nonequilibrium electromotive force. I. Measurements in a continuously stirred tank reactor

    NASA Astrophysics Data System (ADS)

    Keizer, Joel; Chang, On-Kok

    1987-10-01

    Based on a statistical thermodynamic theory, it has been predicted [J. Keizer, J. Chem. Phys. 82, 2751 (1985)] that at nonequilibrium steady states the electromotive force (EMF) of an electrochemical cell will differ from the local equilibrium value given by the Nernst equation. We describe here experiments designed to test this prediction for aqueous solutions of Fe2+ and Fe3+ in sulfate buffer. Using a continuously stirred tank reactor driven by a peristaltic pump, a feed solution containing Fe2+ and Fe3+ was mixed with a second feed solution containing the oxidant sodium peroxydisulfate Na2S2O8. The reaction leads to a steady nonequilibrium mixture, which at acidic pH in sulfate buffer is composed of Fe2+ and the ferric sulfate complexes FeSO+4 and Fe(SO4)-2. The EMF of this half-cell was measured vs a saturated calomel reference electrode as a function of residence time in the reactor. These potentials were compared to the Nernst potential calculated on the basis of the concentration ratio of Fe2+ to total Fe3+ at the steady states. The Nernst potential was reproducibly larger than the measured EMF by values that depended on the concentration ratio of Fe2+/Fe3+ in the feed solution and the residence time. The largest deviations were -1.8 mV, which occurred when the Fe2+/Fe3+ ratio was small and the residence time was about 40 s. We have ruled out streaming potentials, junction potentials, and incomplete mixing as the origin of this effect. We show that the dependence of the nonequilibrium portion of the EMF on feed concentrations and residence time is in good agreement with calculations based on methods that are described in the second paper in this series.

  4. Electromotive force analysis of current transformer during lightning surge inflow using Fourier series expansion

    NASA Astrophysics Data System (ADS)

    Kim, Youngsun

    2017-05-01

    The most common structure used for current transformers (CTs) consists of secondary windings around a ferromagnetic core past the primary current being measured. A CT used as a surge protection device (SPD) may experience large inrushes of current, like surges. However, when a large current flows into the primary winding, measuring the magnitude of the current is difficult because the ferromagnetic core becomes magnetically saturated. Several approaches to reduce the saturation effect are described in the literature. A Rogowski coil is representative of several devices that measure large currents. It is an electrical device that measures alternating current (AC) or high-frequency current. However, such devices are very expensive in application. In addition, the volume of a CT must be increased to measure sufficiently large currents, but for installation spaces that are too small, other methods must be used. To solve this problem, it is necessary to analyze the magnetic field and electromotive force (EMF) characteristics when designing a CT. Thus, we proposed an analysis method for the CT under an inrush current using the time-domain finite element method (TDFEM). The input source current of a surge waveform is expanded by a Fourier series to obtain an instantaneous value. An FEM model of the device is derived in a two-dimensional system and coupled with EMF circuits. The time-derivative term in the differential equation is solved in each time step by the finite difference method. It is concluded that the proposed algorithm is useful for analyzing CT characteristics, including the field distribution. Consequently, the proposed algorithm yields a reference for obtaining the effects of design parameters and magnetic materials for special shapes and sizes before the CT is designed and manufactured.

  5. Electro-optical processor for measuring displacement employing the Talbot and the nonsteady-state photo-electromotive force effects.

    PubMed

    Rodriguez-Montero, P; Sánchez-de-la-Llave, D; Mansurova, S

    2014-01-01

    We present a device for measuring displacement based on the Talbot and the nonsteady photo-electromotive force effects. The proposed device does not require any numerical signal processing since its output signal is, in appropriate regions, linearly related to the measured displacement. The proposed system requires an illuminating field with a sinusoidal amplitude distribution and low fringe visibility. The dynamic range can be adjusted according to the illuminating field spatial period or wavelength. Displacements with an estimated resolution better than 10 μm in a dynamic range of 1.5 mm were detected using a sinusoidal amplitude grating with a period d=100 μm.

  6. Novel Approach in Sensorless Speed Control of Salient Axial-Gap Self-Bearing Motor Using Extended Electromotive Force

    NASA Astrophysics Data System (ADS)

    Nguyen, Quang-Dich; Ueno, Satoshi

    Axial-gap self-bearing motor (AGBM) is an electrical combination of an axial flux motor and a thrust magnetic bearing, hence it can support rotation and magnetic levitation without any additional windings. The goal of this paper is utilization of the state observer to research a new capability of sensorless speed control of a salient AGBM. First, analytical and theoretical evaluation for a sensorless speed vector control of a salient AGBM is presented. The approach is based on the estimation of the extended electromotive force (EEMF) through a Luenberger Observer (LO) with help of reference stator voltages, measured stator currents and measured axial displacement. Then, experiment is implemented based on dSpace1104 with two three-phase inverters. The experimental results confirm that the AGBM can simultaneously produce levitation force and rotational torque. Moreover, speed and axial displacement can be independently controlled without speed sensor.

  7. Speckle photo-electromotive force in Bi12SiO20: Effect of the speckle size

    NASA Astrophysics Data System (ADS)

    Salazar, Ángel

    2013-07-01

    A study of the speckle photo-electromotive force (PEMF) in a photorefractive sensor of amplitudes of micro-oscillations is presented. The experimental behavior of the first harmonic of the photocurrent generated as a function of the average speckle diameter and the oscillation amplitude of the speckle pattern is analyzed for a sensor implemented with a Bi12SiO20 (BSO) crystal. For a given light intensity, a nearly constant value of the maximum amplitude of the first harmonic was experimentally observed for the range of speckle sizes considered. This experimental result and the linear dependence of the vibration amplitude yielding the maximum of the photocurrent as a function of the speckle diameter were appropriately described by the mathematical model considered. Results show the possibility of adequately selecting the speckle size to optimize the output of speckle PEMF-based sensors depending on the oscillation amplitude to be measured.

  8. Noninvasive detection of unevenly magnetized permanent magnet of a brushless dc motor by characterizing back electromotive force

    NASA Astrophysics Data System (ADS)

    Lee, C. I.; Jang, G. H.

    2009-04-01

    Uneven magnetization of permanent magnets (PMs) is one of the major sources of unbalanced magnetic force and torque ripple, which excite a brushless dc (BLDC) motor. This paper investigates the frequency contents of the back electromotive force (BEMF) due to the unevenly magnetized PMs in a BLDC motor. The magnetic field of a BLDC motor is solved by using the finite element method, and the BEMF is calculated by differentiating the flux linkage with respect to time. The characteristics of BEMF are investigated by using the spectral analysis. Magnetic flux density of the ideally magnetized PMs has the harmonics of the pole-pair number, but unevenly magnetized PMs generate the additional harmonics. This research shows numerically and experimentally that the frequency components of the BEMF are determined by the least common multiple between the frequency contents of magnetic flux density from the PMs and the slot number per phase. It also shows that the magnetized status of the PMs of a BLDC can be noninvasively identified by monitoring the frequencies and the amplitudes of BEMF.

  9. Determination of Gibbs Energy of Formation of Molybdenum-Boron Binary System by Electromotive Force Measurement Using Solid Electrolyte

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hiroaki; Morishita, Masao; Yamamoto, Takeo; Furukawa, Kazuma

    2011-02-01

    The standard Gibbs energies of formation of Mo2B, αMoB, Mo2B5, and MoB4 in the molybdenum-boron binary system were determined by measuring electromotive forces of galvanic cells using an Y2O3-stabilized ZrO2 solid oxide electrolyte. The results are as follows: begin{aligned} Updelta_{{f}} {{G}}^circ ( {{{Mo}}2 {{B}}} )/{{J}} {{mol}}^{ - 1} & = - 193100 + 44.10T ± 700( {1198{{ K to }}1323{{ K}}( {925^circ {{C to }}1050^circ {{C}}} )} ) \\ Updelta_{{f}} {{G}}^circ (α {{MoB}})/{{J}} {{mol}}^{ - 1} & = - 164000 + 26.45T ± 700( {1213{{ K to }}1328{{ K}}( {940^circ {{C to }}1055^circ {{C}}} )} ) \\ Updelta_{{f}} {{G}}^circ ( {{{Mo}}2 {{B}}5 } )/{{J}} {{mol}}^{ - 1} & = - 622500 + 117.0T ± 3000( {1205{{ K to }}1294{{ K}}( {932^circ {{C to }}1021^circ {{C}}} )} ) \\ Updelta_{{f}} {{G}}^circ ( {{{MoB}}4 } )/{{J}} {{mol}}^{ - 1} & = - 387300 + 93.53T ± 3000( {959{{ K to }}1153{{ K}}( {686^circ {{C to }}880^circ {{C}}} )} ) \\ where the standard pressure is 1 bar (100 kPa).

  10. Electromotive force and huge magnetoresistance in magnetic tunnel junctions with zinc-blende MnAs nano-magnets

    NASA Astrophysics Data System (ADS)

    Hai, Pham Nam

    2010-03-01

    For nanostructures such as magnetic nanowires or spin valves, it is theoretically predicted that an electromotive force (emf) arises from a time-varying magnetization in a static magnetic field [1]. This reflects the conversion of magnetic energy to electrical energy. Here we show that such an emf can indeed be induced by a static magnetic field in magnetic tunnel junctions containing zinc-blende (ZB) MnAs quantum nano-magnets. The ZB MnAs nanomagnets are coupled to a NiAs-structure hexagonal MnAs top electrode through an AlAs tunnel barrier, and to a GaAs:Be bottom electrode through a GaAs barrier. Under a static magnetic field, an emf of up to 7 mV was observed for a time scale of 10^2˜10^3 sec. This emf is induced by a co-tunneling process of electrons and magnetization of ZB MnAs nanomagnets subject to a strong Coulomb blockade of 50 meV. Huge magnetoresistance of up to 100,000% is observed for certain bias voltages. Our results strongly suggest that Faraday's Law of induction must be generalized to account for purely spin effects in magnetic nanostructures [2]. The author thanks S. Ohya, M. Tanaka, S.E. Barnes and M. Maekawa for their collaboration.[4pt] [1] S. E. Barnes et al. APL 89, 122507 (2006); PRL 98, 246601 (2007).[0pt] [2] P. N. Hai et al., Nature 458, 489 (2009).

  11. On the nonlinear on-off dynamics of a butterfly valve actuated by an induced electromotive force

    NASA Astrophysics Data System (ADS)

    Kwuimy, C. A. Kitio; Ramakrishnan, S.; Nataraj, C.

    2013-11-01

    In this paper, we study the nonlinear dynamics of a butterfly valve actuated by the induced electromotive force (emf) of a permanent magnet, with a focus on the on-off dynamics of the valve and its nonlinear response under ambient perturbation. The complex interplay between the electromagnetic, hydrodynamic and mechanical forces leads to a fundamentally multiphysical, nonlinear dynamical model for the problem. First, we analyze the stability of the on-off conditions in terms of three critical dynamical parameters - the actuating DC voltage, inlet velocity and the opening angle. Next, the response of the system to perturbations around the equilibrium points is studied in terms of the frequency response using the method of multiple scales. Finally, evidence of fractality is established using Melnikov analysis and a plot of the basins of attraction. The results reported in the article, in addition to being of fundamental theoretical interest, are expected to impact practical design considerations of electromechanical butterfly valves. For a voltage ve>vc, theoretically, the system may undergo bifurcations into the physically infeasible domain α>αm (beyond the physical boundary). Practically however, this jump cannot be realized due to the stopper in the plunger. In other words, the valve will completely close the pipe under this condition, leading to catastrophic behavior. For a voltage ve

  12. Determination of Gibbs Energy of Mixing of Tungsten-Boron Binary System by Electromotive Force Measurement Using Solid Electrolyte

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hiroaki; Morishita, Masao; Miyake, Yuta; Hiramatsu, Shusuke

    2017-02-01

    The thermodynamic properties for the tungsten-boron binary system were determined by measuring electromotive forces of galvanic cells using an Y2O3-stabilized ZrO2 solid oxide electrolyte. Assuming that W2B and αWB are the stoichiometric compounds, and W2B5-x and W1-x B3 are the nonstoichiometric compounds having solubility widths of 0.670 ≤ X B ≤ 0.690 and 0.805 ≤ X B ≤ 0.822, respectively, they were treated as the intermediate phases of W0.667B0.333, αW0.50B0.50, W0.330B0.670 W0.310B0.690, and W0.195B0.805 W0.178B0.822. The Gibbs energies of mixing, ∆mix G, determined in the present study are listed as follows: Δ_{mix} G(W_{0.667} B_{0.333} )/{J} {mol}^{ - 1} = {-}78070 + 26.01T ± 70 [1305{-}1422{K}(1032{-}1149° C)], & Δ_{mix} G(α W_{0.50} B_{0.50} )/{J} {mol}^{ - 1} = {-}86140 + 20.19T ± 200 [1310{-}1399{K}(1037{-}1126° C)], & Δ_{mix} G(W_{0.330} B_{0.670} )/{J} {mol}^{ - 1} = {-}78910 + 18.11T ± 200 [1228{-}1410{K}(955{-}1137° C)], & Δ_{mix} G(W_{0.310} B_{0.690} )/{J} {mol}^{ - 1} = {-}77350 + 17.52T ± 500 [1228{-}1410{K}(955{-}1137° C)], & Δ_{mix} G(W_{0.195} B_{0.805} )/{J} {mol}^{ - 1} = {-}63920 + 12.08T ± 500 [1170{-}1340{K}(897{-}1067° C)], & Δ_{mix} G(W_{0.178} B_{0.822} )/{J} {mol}^{ - 1} = {-}60090 + 11.15T ± 200 [1170{-}1340{K}(897{-}1067° C)]. Using the thermodynamic properties determined in the present study, the composition-oxygen partial pressure diagram of the tungsten-boron-oxygen system was constructed under the conditions at 1273 K (1000 °C) and a total pressure of 1 bar (100 kPa). It is useful to understand the oxidation property of tungsten-boron binary alloys.

  13. Determination of Gibbs Energy of Mixing of Tungsten-Boron Binary System by Electromotive Force Measurement Using Solid Electrolyte

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hiroaki; Morishita, Masao; Miyake, Yuta; Hiramatsu, Shusuke

    2017-06-01

    The thermodynamic properties for the tungsten-boron binary system were determined by measuring electromotive forces of galvanic cells using an Y2O3-stabilized ZrO2 solid oxide electrolyte. Assuming that W2B and αWB are the stoichiometric compounds, and W2B5- x and W1- x B3 are the nonstoichiometric compounds having solubility widths of 0.670 ≤ X B ≤ 0.690 and 0.805 ≤ X B ≤ 0.822, respectively, they were treated as the intermediate phases of W0.667B0.333, αW0.50B0.50, W0.330B0.670 W0.310B0.690, and W0.195B0.805 W0.178B0.822. The Gibbs energies of mixing, ∆mix G, determined in the present study are listed as follows: Δ_{{mix}} G({W}_{0.667} {B}_{0.333} )/{{J}} {{mol}}^{ - 1} = {-}78070 + 26.01T ± 70 [1305{-}1422{{ K}}(1032{-}1149°C)], Δ_{{mix}} G(α {W}_{0.50} {B}_{0.50} )/{{J}} {{mol}}^{ - 1} = {-}86140 + 20.19T ± 200 [1310{-}1399{{ K }}(1037{-}1126°C)], Δ_{{mix}} G({W}_{0.330} {B}_{0.670} )/{{J}} {{mol}}^{ - 1} = {-}78910 + 18.11T ± 200 [1228{-}1410{{ K }}(955{-}1137°C)], ; Δ_{{mix}} G({W}_{0.310} {B}_{0.690} )/{{J}} {{mol}}^{ - 1} = {-}77350 + 17.52T ± 500 [1228{-}1410{{ K }}(955{-}1137°C)], Δ_{{mix}} G({W}_{0.195} {B}_{0.805} )/{{J}} {{mol}}^{ - 1} = {-}63920 + 12.08T ± 500 [1170{-}1340{{ K }}(897{-}1067°C)], Δ_{{mix}} G({W}_{0.178} {B}_{0.822} )/{{J}} {{mol}}^{ - 1} = {-}60090 + 11.15T ± 200 [1170{-}1340{{ K }}(897{-}1067°C)]. Using the thermodynamic properties determined in the present study, the composition-oxygen partial pressure diagram of the tungsten-boron-oxygen system was constructed under the conditions at 1273 K (1000 °C) and a total pressure of 1 bar (100 kPa). It is useful to understand the oxidation property of tungsten-boron binary alloys.

  14. Electric organ discharges and near-field spatiotemporal patterns of the electromotive force in a sympatric assemblage of Neotropical electric knifefish.

    PubMed

    Waddell, Joseph C; Rodríguez-Cattáneo, Alejo; Caputi, Angel A; Crampton, William G R

    2016-10-01

    Descriptions of the head-to-tail electric organ discharge (ht-EOD) waveform - typically recorded with electrodes at a distance of approximately 1-2 body lengths from the center of the subject - have traditionally been used to characterize species diversity in gymnotiform electric fish. However, even taxa with relatively simple ht-EODs show spatiotemporally complex fields near the body surface that are determined by site-specific electrogenic properties of the electric organ and electric filtering properties of adjacent tissues and skin. In Brachyhypopomus, a pulse-discharging genus in the family Hypopomidae, the regional characteristics of the electric organ and the role that the complex 'near field' plays in communication and/or electrolocation are not well known. Here we describe, compare, and discuss the functional significance of diversity in the ht-EOD waveforms and near-field spatiotemporal patterns of the electromotive force (emf-EODs) among a species-rich sympatric community of Brachyhypopomus from the upper Amazon. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Characterisation of the turbulent electromotive force and its magnetically-mediated quenching in a global EULAG-MHD simulation of solar convection

    NASA Astrophysics Data System (ADS)

    Simard, Corinne; Charbonneau, Paul; Dubé, Caroline

    2016-10-01

    We perform a mean-field analysis of the EULAG-MHD millenium simulation of global magnetohydrodynamical convection presented in Passos and Charbonneau (2014). The turbulent electromotive force (emf) operating in the simulation is assumed to be linearly related to the cyclic axisymmetric mean magnetic field and its first spatial derivatives. At every grid point in the simulation's meridional plane, this assumed relationship involves 27 independent tensorial coefficients. Expanding on Racine et al. (2011), we extract these coefficients from the simulation data through a least-squares minimization procedure based on singular value decomposition. The reconstructed α -tensor shows good agreement with that obtained by Racine et al. (2011), who did not include derivatives of the mean-field in their fit, as well as with the α -tensor extracted by Augustson et al. (2015) from a distinct ASH MHD simulation. The isotropic part of the turbulent magnetic diffusivity tensor β is positive definite and reaches values of 5.0 ×107 m2 s-1 in the middle of the convecting fluid layers. The spatial variations of both αϕϕ and βϕϕ component are well reproduced by expressions obtained under the Second Order Correlation Approximation, with a good matching of amplitude requiring a turbulent correlation time about five times smaller than the estimated turnover time of the small-scale turbulent flow. By segmenting the simulation data into epochs of magnetic cycle minima and maxima, we also measure α - and β -quenching. We find the magnetic quenching of the α -effect to be driven primarily by a reduction of the small-scale flow's kinetic helicity, with variations of the current helicity playing a lesser role in most locations in the simulation domain. Our measurements of turbulent diffusivity quenching are restricted to the βϕϕ component, but indicate a weaker quenching, by a factor of ≃ 1.36, than of the α -effect, which in our simulation drops by a factor of three between

  16. Force-proportional reinforcement: pimozide does not reduce rats' emission of higher forces for sweeter rewards.

    PubMed

    Kirkpatrick, M A; Fowler, S C

    1989-02-01

    A two-step force-proportional reinforcement procedure was used to assess the efficacy of a sucrose reward under neuroleptic challenge. The force-proportional reinforcement method entails an increase in the quality of reward contingent upon higher force-emission. This paradigm was conceived as a rate-free means of addressing the putative anhedonic effects of dopaminergic receptor-blocking agents. Results failed to support the anhedonia interpretation of neuroleptic-induced response decrements: Pimozide did not diminish the ability of a high-concentration sucrose solution to maintain elevated response forces. Alternatives to the anhedonia interpretation were discussed with emphasis on the drug's motor effects in the temporal domain.

  17. Tire Force Estimation using a Proportional Integral Observer

    NASA Astrophysics Data System (ADS)

    Farhat, Ahmad; Koenig, Damien; Hernandez-Alcantara, Diana; Morales-Menendez, Ruben

    2017-01-01

    This paper addresses a method for detecting critical stability situations in the lateral vehicle dynamics by estimating the non-linear part of the tire forces. These forces indicate the road holding performance of the vehicle. The estimation method is based on a robust fault detection and estimation approach which minimize the disturbance and uncertainties to residual sensitivity. It consists in the design of a Proportional Integral Observer (PIO), while minimizing the well known H ∞ norm for the worst case uncertainties and disturbance attenuation, and combining a transient response specification. This multi-objective problem is formulated as a Linear Matrix Inequalities (LMI) feasibility problem where a cost function subject to LMI constraints is minimized. This approach is employed to generate a set of switched robust observers for uncertain switched systems, where the convergence of the observer is ensured using a Multiple Lyapunov Function (MLF). Whilst the forces to be estimated can not be physically measured, a simulation scenario with CarSimTM is presented to illustrate the developed method.

  18. Principled Improvement in Science: Forces and proportional relations in early secondary-school teaching

    NASA Astrophysics Data System (ADS)

    Howe, Christine; Ilie, Sonia; Guardia, Paula; Hofmann, Riikka; Mercer, Neil; Riga, Fran

    2015-01-01

    In response to continuing concerns about student attainment and participation in science and mathematics, the epiSTEMe project took a novel approach to pedagogy in these two disciplines. Using principles identified as effective in the research literature (and combining these in a fashion not previously attempted), the project developed topic modules for early secondary-school teaching in the UK, arranged for their implementation in classrooms, and evaluated the results. This paper reports the development, implementation, and evaluation of one of the epiSTEMe science modules. Entitled Forces and Proportional Relations, the module covers standard curricular material in the domain of forces, while paying particular attention to the proportional nature of many key constructs. It was developed in collaboration with a small group of teachers; implemented subsequently in 16 classrooms, in all cases involving students from the first year of secondary school; and evaluated through comparison with first-year students in 13 control classrooms who were studying the topic using established methods. Evaluation addressed topic mastery and opinions about the topic and the manner in which it was taught. While further research is required before definite conclusions are warranted, results relating to topic mastery provide grounds for optimism about the epiSTEMe approach. Furthermore, student opinions about the module were positive.

  19. The phosphate potential maintained by mitochondria in State 4 is proportional to the proton-motive force.

    PubMed

    Woelders, H; van der Zande, W J; Colen, A M; Wanders, R J; van Dam, K

    1985-01-07

    Evidence is presented for a proportional relationship between the extramitochondrial phosphate potential (delta Gexp) and the proton-motive force (delta mu H+) across the mitochondrial membrane in rat-liver mitochondria oxidising succinate in State 4, when delta mu H+ is varied by addition of uncouplers or malonate. This relationship was found when precautions were taken to minimise interference with the determination of delta Gexp and delta mu H+ by intramitochondrial nucleotides, adenylate kinase activity, the quenching method, and delta mu H+-dependent changes in matrix volume. A non-proportional delta Gexp/delta mu H+ relationship was obtained when these precautions were omitted. Our results do not support mosaic protonic coupling, but are not necessarily in conflict with other localised coupling schemes.

  20. The Electromotive Series and Other Non-Absolute Scales

    NASA Astrophysics Data System (ADS)

    Peckham, Gavin D.

    1998-01-01

    This article describes an analogy which may be used to illustrate the principles that underlie the establishment of non-absolute scales of measurements that are evaluated relative to a chosen reference point. The analogy is interwoven with the establishment of the electromotive series, but may be extended to other parameters such as the Celsius and Fahrenheit temperature scales, potential energies, formation and reaction enthalpies, etc.

  1. Investigation of the mechanisms of action behind Electromotive Drug Administration (EMDA)

    PubMed Central

    Vásquez, Juan Luis; Miklavčič, Damijan; Hermann, Gregers G.G.; Gehl, Julie

    2016-01-01

    Objective Bladder cancer is a cause of considerable morbidity worldwide. Electromotive Drug Administration is a method that combines intravesical chemotherapy with local electric field application. Electroporation has been suggested among other mechanisms as having a possible role in the therapy, so the goal of the present study was to investigate the electric fields present in the bladder wall during the treatment to determine which mechanisms might be involved. Material and Methods Electromotive Drug Administration involves applying intravesical mitomycin C with direct current of 20 mA delivered through a catheter electrode for 30 min. For numerical electric field computation we built a 3-D nonhomogeneous patient specific model based on CT images and used finite element method simulations to determine the electric fields in the whole body. Results Results indicate that highest electric field in the bladder wall was 37.7 V/m. The mean electric field magnitude in the bladder wall was 3.03 V/m. The mean magnitude of the current density in the bladder wall was 0.61 A/m2. Conclusions The present study shows that electroporation is not the mechanism of action in EMDA. A more likely explanation of the mechanism of action is iontophoretic forces increasing the mitomycin C concentration in the bladder wall. PMID:27635313

  2. Digital current regulator for proportional electro-hydraulic valves with unknown disturbance rejection.

    PubMed

    Canuto, Enrico; Acuña-Bravo, Wilber; Agostani, Marco; Bonadei, Marco

    2014-07-01

    Solenoid current regulation is well-known and standard in any proportional electro-hydraulic valve. The goal is to provide a wide-band transfer function from the reference to the measured current, thus making the solenoid a fast and ideal force actuator within the limits of the power supplier. The power supplier is usually a Pulse Width Modulation (PWM) amplifier fixing the voltage bound and the Nyquist frequency of the regulator. Typical analog regulators include three main terms: a feedforward channel, a proportional feedback channel and the electromotive force compensation. The latter compensation may be accomplished by integrative feedback. Here the problem is faced through a model-based design (Embedded Model Control), on the basis of a wide-band embedded model of the solenoid which includes the effect of eddy currents. To this end model parameters must be identified. The embedded model includes a stochastic disturbance dynamics capable of estimating and correcting the electromotive contribution together with parametric uncertainty, variability and state dependence. The embedded model which is fed by the measured current and the supplied voltage becomes a state predictor of the controllable and disturbance dynamics. The control law combines reference generator, state feedback and disturbance rejection to dispatch the PWM amplifier with the appropriate duty cycle. Modeling, identification and control design are outlined together with experimental result. Comparison with an existing analog regulator is also provided.

  3. [Intravesical therapy with mitomycin through electromotive drug administration].

    PubMed

    Verri, Cristian; Liberati, Emanuele; Celestino, Francesco; De Carlo, Francesco; Torelli, Fiammetta; Di Stasi, Savino M

    2013-01-01

    In the management of non-muscle invasive bladder cancer (NMIBC), high-level evidence supports the widespread practice of intravesical therapy with mitomycin-C (MMC). Randomized trials showed a significant reduction in short-term recurrence compared with transurethral resection of bladder tumor (TURBT) alone, but little effect on long-term and no impact at all in preventing progression. Electromotive drug administration (EMDA®) offers a means of controlling and enhancing the tissue transport of certain drugs, in order to increase their efficacy. In both laboratory and clinical studies, intravesical electromotive drug administration (EMDA) increases MMC bladder uptake, resulting in an improved clinical efficacy in NMIBC without systemic side effects. New frameworks for treatment of NMIBC - e.g., sequential intravesical BCG and EMDA/MMC, as well as intravesical EMDA/MMC immediately before TURBT - have provided promising preliminary results with higher remission rates and longer remission times, and they are a priority to minimise the costs of disease management. These findings suggest EMDA-enhanced MMC efficacy against urothelial cancer could be a major therapeutic breakthrough in the treatment of NMIBC.

  4. Initial Plasma Testing of the Ion Proportional Surface Emission Cathode

    DTIC Science & Technology

    2008-07-15

    electrodynamic tether (EDT)𔃼 is a space vehicle that utilizes the I x B electromotive force between a current-carrying wire and a magnetic field and...for the August experiment series to 32 inches in order to reduce the ion flux. Experiments were conducted in the Jumbo space simulation chamber at

  5. Electromotive administration of oxybutynin into the human bladder wall.

    PubMed

    Di Stasi, S M; Giannantoni, A; Massoud, R; Cortese, C; Vespasiani, G; Micali, F

    1997-07-01

    To compare concentrations of oxybutynin in the human bladder wall after either passive delivery (PD) or electromotive administration (EMDA). Tissue sections of human bladder were inserted into a diffusion cell with urothelium exposed to the donor compartment containing oxybutynin (4.5 mg. in 100 ml. NaCl 0.45%) and an anode. Twelve paired experiments, "current 5 mA/no current", were conducted over 15 minutes. Oxybutynin tissue contents were measured and tissue viability, morphology and oxybutynin stability were assessed. Mean oxybutynin tissue concentrations were 3.84 micrograms./gm. in samples exposed to EMDA and 0.87 microgram./gm. in samples exposed to PD (p = 0.0006). The mean coefficients of variation were 57.85% in EMDA experiments and 89.78% in PD experiments. Tissues were viable and undamaged histologically and no oxybutynin structural modification was observed. EMDA enhances oxybutynin administration into viable bladder wall and reduces the variability in drug delivery rate.

  6. Electromotive delivery of mitomycin C into human bladder wall.

    PubMed

    Di Stasi, S M; Vespasiani, G; Giannantoni, A; Massoud, R; Dolci, S; Micali, F

    1997-03-01

    The aim of this investigation was to establish an appropriate tissue pharmacokinetic model to compare concentrations of mitomycin C (MMC) in the human bladder wall after either passive delivery or electromotive administration (EMDA) and to evaluate the effects of EMDA on tissue morphology and MMC structure. Tissue sections of human bladder were inserted into two chamber cells with urothelium exposed to donor compartments containing MMC (10 mg in 100 ml of 0.24% NaCl solution) and an anode and with serosa exposed to receptor compartments containing 100 ml of 0.9% NaCl solution and a cathode. Fourteen paired experiments ("current 5 mA/no current") were conducted over 15 min; MMC tissue content was assessed by high-pressure liquid chromatography. Tissue viability and morphology and MMC stability were assessed by trypan blue exclusion test, tissue pH, histological analysis, and mass spectrometry analysis. MMC concentrations were increased, and variability in drug delivery rate was reduced in all tissue in samples exposed to electric current. Tissues were viable and undamaged histologically, and no MMC structural modification was observed. In conclusion, EMDA enhances administration of MMC into viable bladder wall tissue and reduces the variability in drug delivery rates.

  7. Intravesical electromotive drug administration for the treatment of non-infectious chronic cystitis.

    PubMed

    Riedl, C R; Knoll, M; Plas, E; Stephen, R L; Pflüger, H

    1997-01-01

    Seventeen patients with non-infectious chronic cystitis (NICC) (9 with interstitial cystitis, 6 patients with radiation cystitis, 1 with chemocystitis and 1 with lupoid cystitis) were treated with electromotive administration of intravesical lidocaine and dexamethasone followed by hydrodistension of the bladder. Complete resolution of symptoms for an average of 7.5 months was observed in 11 patients (65%), partial improvement in 4 (23.5%). In this series no complications occurred. Electromotive drug administration (EMDA) and cystodistension were well tolerated by all patients. The treatment was performed on an outpatient basis, thus reducing therapeutic costs. The results presented demonstrate that the combination of EMDA and bladder hydrodistension is an effective first-line treatment for NICC patients.

  8. Intravesical electromotive administration of oxybutynin in patients with detrusor hyperreflexia unresponsive to standard anticholinergic regimens.

    PubMed

    Di Stasi, S M; Giannantoni, A; Vespasiani, G; Navarra, P; Capelli, G; Massoud, R; Stephen, R L

    2001-02-01

    About 15% to 20% of patients with detrusor hyperreflexia do not benefit from oral oxybutynin regimens, frequently because of unpleasant side effects. Several reports indicate that intravesical oxybutynin is effective in many of these patients but there are some who still fail to respond. A select group of 10 adults with detrusor hyperreflexia unresponsive to standard oral and intravesical oxybutynin regimens were treated at weekly intervals with 5 mg. oxybutynin orally, or 5 mg. oxybutynin in 100 ml. intravesically for 60 minutes of passive diffusion and for 30 minutes with 5 mA. electrical current. Each treatment (plus oral placebo and 2 intravesical controls) was associated with an 8-hour, full urodynamic monitoring session, and periodic blood and bladder content sampling. There was no significant objective improvement with oral or intravesical passive diffusion oxybutynin. Conversely there was significant improvement in 5 of 6 objective urodynamic measurements with intravesical electromotive oxybutynin. Plasma profiles were a single peak and decay following oral oxybutynin and 2 distinct peaks with intravesical passive diffusion and electromotive oxybutynin. Area under the curve for intravesical passive diffusion were 709 ng. per 8 hours versus oral 1,485 (p <0.05) versus intravesical electromotive 2,781 (p <0.001). Bladder content samples confirmed oxybutynin absorption. Oral oxybutynin caused anticholinergic side effects in 7 of 10 patients. There were no side effects with intravesical passive diffusion or electromotive administrations. Accelerated intravesical administration results in greater bioavailability and increased objective benefits without side effects in previously unresponsive patients compared with oral and intravesical passive diffusion oxybutynin administration.

  9. Electromotive force measurements on cells involving beta-alumina solid electrolyte

    NASA Technical Reports Server (NTRS)

    Choudhury, N. S.

    1973-01-01

    Open-circuit emf measurements have been made to demonstrate that a two-phase, polycrystalline mixture of beta-alumina and alpha-alumina could be used as a solid electrolyte in galvanic cells with reversible electrodes fixing oxygen or aluminum chemical potentials. These measurements indicate that such a two-phase solid electrolyte may be used to monitor oxygen chemical potentials as low as that corresponding to Al and Al2O3 coexistence (potentials of about 10 to the minus 47th power atm at 1000 K). The activity of Na2O in beta-alumina in coexistence with alpha-alumina was also determined by emf measurements.

  10. Electromotive force measurements on cells involving beta-alumina solid electrolyte

    NASA Technical Reports Server (NTRS)

    Choudhury, N.

    1973-01-01

    Open circuit emf measurements have been made to demonstrate that a two-phase, polycrystalline mixture of beta- alumina and alpha-alumina could be used as a solid electrolyte in galvanic cells with reversible electrodes fixing oxygen or aluminum chemical potentials. These measurements indicate that such a two phase solid electrolyte can be used to monitor oxygen chemical potentials as low as that corresponding to Al, Al2O3 coexistence. The activity of Na2O in beta-alumina in coexistence with alpha-alumina was also determined by emf measurements.

  11. Random myosin loss along thick-filaments increases myosin attachment time and the proportion of bound myosin heads to mitigate force decline in skeletal muscle

    PubMed Central

    Tanner, Bertrand C.W.; McNabb, Mark; Palmer, Bradley M.; Toth, Michael J.; Miller, Mark S.

    2014-01-01

    Diminished skeletal muscle performance with aging, disuse, and disease may be partially attributed to the loss of myofilament proteins. Several laboratories have found a disproportionate loss of myosin protein content relative to other myofilament proteins, but due to methodological limitations, the structural manifestation of this protein loss is unknown. To investigate how variations in myosin content affect ensemble cross-bridge behavior and force production we simulated muscle contraction in the half-sarcomere as myosin was removed either i) uniformly, from the Z-line end of thick-filaments, or ii) randomly, along the length of thick-filaments. Uniform myosin removal decreased force production, showing a slightly steeper force-to-myosin content relationship than the 1:1 relationship that would be expected from the loss of cross-bridges. Random myosin removal also decreased force production, but this decrease was less than observed with uniform myosin loss, largely due to increased myosin attachment time (ton) and fractional cross-bridge binding with random myosin loss. These findings support our prior observations that prolonged ton may augment force production in single fibers with randomly reduced myosin content from chronic heart failure patients. These simulation also illustrate that the pattern of myosin loss along thick-filaments influences ensemble cross-bridge behavior and maintenance of force throughout the sarcomere. PMID:24486373

  12. Random myosin loss along thick-filaments increases myosin attachment time and the proportion of bound myosin heads to mitigate force decline in skeletal muscle.

    PubMed

    Tanner, Bertrand C W; McNabb, Mark; Palmer, Bradley M; Toth, Michael J; Miller, Mark S

    2014-06-15

    Diminished skeletal muscle performance with aging, disuse, and disease may be partially attributed to the loss of myofilament proteins. Several laboratories have found a disproportionate loss of myosin protein content relative to other myofilament proteins, but due to methodological limitations, the structural manifestation of this protein loss is unknown. To investigate how variations in myosin content affect ensemble cross-bridge behavior and force production we simulated muscle contraction in the half-sarcomere as myosin was removed either (i) uniformly, from the Z-line end of thick-filaments, or (ii) randomly, along the length of thick-filaments. Uniform myosin removal decreased force production, showing a slightly steeper force-to-myosin content relationship than the 1:1 relationship that would be expected from the loss of cross-bridges. Random myosin removal also decreased force production, but this decrease was less than observed with uniform myosin loss, largely due to increased myosin attachment time (ton) and fractional cross-bridge binding with random myosin loss. These findings support our prior observations that prolonged ton may augment force production in single fibers with randomly reduced myosin content from chronic heart failure patients. These simulations also illustrate that the pattern of myosin loss along thick-filaments influences ensemble cross-bridge behavior and maintenance of force throughout the sarcomere. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Intravesical oxybutynin: mode of action assessed by passive diffusion and electromotive administration with pharmacokinetics of oxybutynin and N-desethyl oxybutynin.

    PubMed

    Di Stasi, S M; Giannantoni, A; Navarra, P; Capelli, G; Storti, L; Porena, M; Stephen, R L

    2001-12-01

    A proportion of patients with detrusor hyperreflexia who are unresponsive to oral oxybutynin often benefit from intravesical oxybutynin instillation. To our knowledge the precise mode of action of this method is obscure. In 12 patients with detrusor hyperreflexia who were previously unresponsive to oral and intravesical passive diffusion of 5 mg. oxybutynin we administered 5 mg. oxybutynin orally as well as increased doses of 15 mg. oxybutynin intravesically with passive diffusion and with 15 mA. associated electric current. Each administration mode per patient was associated with an 8-hour urodynamic monitoring session during which oxybutynin and N-desethyl oxybutynin plasma levels, and intravesical oxybutynin uptake were measured. A dose of 5 mg. oxybutynin orally induced no urodynamic improvement with an area under the plasma concentration time curve of combined N-desethyl oxybutynin plus oxybutynin of 16,297 ng./8 hours and an area under the curve ratio of N-desethyl oxybutynin-to-oxybutynin of 11:1. Passive diffusion oxybutynin resulted in 12 mg. oxybutynin intravesical uptake and significant improvement in 3 of 8 urodynamic measurements, although the area under the curve of combined N-desethyl oxybutynin plus oxybutynin was only 2,123 ng./8 hours and the N-desethyl oxybutynin-to-oxybutynin ratio was 1.1:1.0. Electromotive administration of oxybutynin resulted in almost complete intravesical uptake of the 15 mg. dose, significant improvement in all 8 urodynamic measurements and an increased oxybutynin level versus oral and passive diffusion, although the area under the curve of combined N-desethyl oxybutynin plus oxybutynin was 4,574 ng./8 hours and the N-desethyl oxybutynin-to-oxybutynin ratio was inverted at 1.0:1.4. The oral dose of 5 mg. oxybutynin caused anticholinergic side effects in 8 of the 12 patients. Neither intravesical passive diffusion nor electromotive administration caused side effects with an uptake of 12 and 15 mg., respectively. A large

  14. Electromotive Triggering and Single Sweep Analysis of Vestibular Evoked Myogenic Potentials (VEMPs).

    PubMed

    Hecker, Dietmar J; Lohscheller, Joerg; Schorn, Bianca; Koch, Klaus Peter; Schick, Bernhard; Dlugaiczyk, Julia

    2014-01-01

    Cervical (c) and ocular (o) vestibular evoked myogenic potentials (VEMPs) provide important tools for measuring otolith function. However, two major drawbacks of this method are encountered in clinical practice. First, recording of oVEMPs is compromised by small n10 amplitudes. Second, VEMP analysis is currently based on the averaging technique, resulting in a loss of information compared to single sweep analysis. Here, we: 1) developed a novel electromotive trigger mechanism for evoking VEMPs by bone-conducted vibration to the forehead and 2) established maximum entropy extraction of complex wavelet transforms for calculation of phase synchronization between VEMP single sweeps. Both c- and oVEMPs were recorded for n=10 healthy individuals. The oVEMP n10 amplitude was consistently higher (right: 24.84±9.71 μV; left: 27.40±14.55 μV) than previously described. Stable VEMP signals were reached after a smaller number of head taps (oVEMPs 6; cVEMPs 11) compared to current recommendations. Phase synchronization vectors and phase shift values were successfully determined for simulated and clinically recorded VEMPs, providing information about the impact of noise and phase jitter on the VEMP signal. Thus, the proposed method constitutes an easy-to-use approach for the fast detection and analysis of VEMPs in clinical practice.

  15. Force.

    ERIC Educational Resources Information Center

    Gamble, Reed

    1989-01-01

    Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)

  16. Force.

    ERIC Educational Resources Information Center

    Gamble, Reed

    1989-01-01

    Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)

  17. Strip Diagrams: Illuminating Proportions

    ERIC Educational Resources Information Center

    Cohen, Jessica S.

    2013-01-01

    Proportional reasoning is both complex and layered, making it challenging to define. Lamon (1999) identified characteristics of proportional thinkers, such as being able to understand covariance of quantities; distinguish between proportional and nonproportional relationships; use a variety of strategies flexibly, most of which are nonalgorithmic,…

  18. Coincidence Proportional Counter

    DOEpatents

    Manley, J H

    1950-11-21

    A coincidence proportional counter having a plurality of collecting electrodes so disposed as to measure the range or energy spectrum of an ionizing particle-emitting source such as an alpha source, is disclosed.

  19. Electromotive force measurements in the combustion wave front during layer-by-layer surface laser sintering of exothermic powder compositions.

    PubMed

    Shishkovskiy, Igor V; Morozov, Yury G; Kuznetsov, Maxim V; Parkin, Ivan P

    2009-05-14

    Electric potentials arise between the combustion wave front and final products during layer-by-layer surface laser sintering of exothermic powder compositions (Ni-Ti, Ni-Al, Ti-Al). By using an analog-digital-analog converter to control the laser movement and hence the exothermic reaction itself, we show that near optimal conditions can be obtained for the formation of layered 3D articles. Comparative results of the structural-phase transformations that occur during laser-controlled SHS in related reaction-capable compositions are also presented.

  20. Performing the triple auto-correlation of picosecond optical pulse train with a photo electromotive force detector

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Mansurova, Svetlana; Moreno Zarate, Pedro; Campos Acosta, Joaquin; Nemov, Sergey A.

    2011-03-01

    vHere, we consider the possibility of involving the photo-EMF detectors in registration of the parameters peculiar to ultrashort optical pulses, and it is compared whit the recently triple correlator via Direct and Cascade Third Harmonic Generation. Knowledge of triple auto-correlation function, whose Fourier transformation shapes the corresponding bispectrum, makes possible recovering such train-average parameters as, for instance, the pulse width and frequency chirp as well as revealing asymmetry of ultra-short pulse envelope. The main advantage of applying the photo-EMF detectors lies in an opportunity to detect triple correlations directly, without any intermediate frequency conversion with optical nonlinear processes in additional crystals. Then, the theory of three-beam-correlations at photosensitive layer of the photo-EMF detector is developed, so that principal possibility of registering the high-order-correlations is demonstrated. It can be done within schematic arrangement including the three-beam Michelson interferometer, so that the obtained high-order-correlations have non-traditional form and need rather specific algorithm for their further processing. Also, the experimental characterizations are presented for gallium arsenide (GaAs) semiconductor and the poly-fluoren 6-co-triphenyldiamine (PF6-TPD) photo-conductor-polymer, which both exhibit the photo-EMF-effect. They both exhibit high-pass transfer functions that give us high vibration stability. This novel approach provides more reliable analyzing train-average parameters of picosecond pulses due to significantly higher level of the output optical signals under processing.

  1. Adaptation through proportion

    NASA Astrophysics Data System (ADS)

    Xiong, Liyang; Shi, Wenjia; Tang, Chao

    2016-08-01

    Adaptation is a ubiquitous feature in biological sensory and signaling networks. It has been suggested that adaptive systems may follow certain simple design principles across diverse organisms, cells and pathways. One class of networks that can achieve adaptation utilizes an incoherent feedforward control, in which two parallel signaling branches exert opposite but proportional effects on the output at steady state. In this paper, we generalize this adaptation mechanism by establishing a steady-state proportionality relationship among a subset of nodes in a network. Adaptation can be achieved by using any two nodes in the sub-network to respectively regulate the output node positively and negatively. We focus on enzyme networks and first identify basic regulation motifs consisting of two and three nodes that can be used to build small networks with proportional relationships. Larger proportional networks can then be constructed modularly similar to LEGOs. Our method provides a general framework to construct and analyze a class of proportional and/or adaptation networks with arbitrary size, flexibility and versatile functional features.

  2. COUNTRY-LEVEL SOCIOECONOMIC INDICATORS ASSOCIATED WITH SURVIVAL PROBABILITY OF BECOMING A CENTENARIAN AMONG OLDER EUROPEAN ADULTS: GENDER INEQUALITY, MALE LABOUR FORCE PARTICIPATION AND PROPORTIONS OF WOMEN IN PARLIAMENTS.

    PubMed

    Kim, Jong In; Kim, Gukbin

    2017-03-01

    This study confirms an association between survival probability of becoming a centenarian (SPBC) for those aged 65 to 69 and country-level socioeconomic indicators in Europe: the gender inequality index (GII), male labour force participation (MLP) rates and proportions of seats held by women in national parliaments (PWP). The analysis was based on SPBC data from 34 countries obtained from the United Nations (UN). Country-level socioeconomic indicator data were obtained from the UN and World Bank databases. The associations between socioeconomic indicators and SPBC were assessed using correlation coefficients and multivariate regression models. The findings show significant correlations between the SPBC for women and men aged 65 to 69 and country-level socioeconomic indicators: GII (r=-0.674, p=0.001), MLP (r=0.514, p=0.002) and PWP (r=0.498, p=0.003). The SPBC predictors for women and men were lower GIIs and higher MLP and PWP (R 2=0.508, p=0.001). Country-level socioeconomic indicators appear to have an important effect on the probability of becoming a centenarian in European adults aged 65 to 69. Country-level gender equality policies in European counties may decrease the risk of unhealthy old age and increase longevity in elders through greater national gender equality; disparities in GII and other country-level socioeconomic indicators impact longevity probability. National longevity strategies should target country-level gender inequality.

  3. Proportional Borda allocations.

    PubMed

    Darmann, Andreas; Klamler, Christian

    2016-01-01

    In this paper we study the allocation of indivisible items among a group of agents, a problem which has received increased attention in recent years, especially in areas such as computer science and economics. A major fairness property in the fair division literature is proportionality, which is satisfied whenever each of the n agents receives at least [Formula: see text] of the value attached to the whole set of items. To simplify the determination of values of (sets of) items from ordinal rankings of the items, we use the Borda rule, a concept used extensively and well-known in voting theory. Although, in general, proportionality cannot be guaranteed, we show that, under certain assumptions, proportional allocations of indivisible items are possible and finding such allocations is computationally easy.

  4. Multiwire proportional counter development

    NASA Technical Reports Server (NTRS)

    1972-01-01

    A test run was made at the Bevatron to check the character of signals induced in an electromagnetic delay line capacitively coupled to the wire cathode plane of a multiwire proportional chamber. In particular, these signals and the behavior of the readout electronics as a function of associated delta-ray production are studied. These measurements are important in assessing the effect of delta-ray background on the spatial resolution attainable for the primary ions. Test results are used to design a multiwire proportional chamber and readout system for use as spatial detectors in a superconducting magnetic spectrometer experiment.

  5. Keep It in Proportion.

    ERIC Educational Resources Information Center

    Snider, Richard G.

    1985-01-01

    The ratio factors approach involves recognizing a given fraction, then multiplying so that units cancel. This approach, which is grounded in concrete operational thinking patterns, provides a standard for science ratio and proportion problems. Examples are included for unit conversions, mole problems, molarity, speed/density problems, and…

  6. Selecting Proportional Reasoning Tasks

    ERIC Educational Resources Information Center

    de la Cruz, Jessica A.

    2013-01-01

    With careful consideration given to task selection, students can construct their own solution strategies to solve complex proportional reasoning tasks while the teacher's instructional goals are still met. Several aspects of the tasks should be considered including their numerical structure, context, difficulty level, and the strategies they are…

  7. Proportioning Cats and Rats

    ERIC Educational Resources Information Center

    Markworth, Kimberly A.

    2012-01-01

    Students may be able to set up a relevant proportion and solve through cross multiplication. However, this ability may not reflect the desired mathematical understanding of the covarying relationship that exists between two variables or the equivalent relationship that exists between two ratios. Students who lack this understanding are likely to…

  8. Intravesical electromotive drug administration for non-muscle invasive bladder cancer.

    PubMed

    Jung, Jae Hung; Gudeloglu, Ahmet; Kiziloz, Halil; Kuntz, Gretchen M; Miller, Alea; Konety, Badrinath R; Dahm, Philipp

    2017-09-12

    Electromotive drug administration (EMDA) is the use of electrical current to improve the delivery of intravesical agents to reduce the risk of recurrence in people with non-muscle invasive bladder cancer (NMIBC). It is unclear how effective this is in comparison to other forms of intravesical therapy. To assess the effects of intravesical EMDA for the treatment of NMIBC. We performed a comprehensive search using multiple databases (CENTRAL, MEDLINE, EMBASE), two clinical trial registries and a grey literature repository. We searched reference lists of relevant publications and abstract proceedings. We applied no language restrictions. The last search was February 2017. We searched for randomised studies comparing EMDA of any intravesical agent used to reduce bladder cancer recurrence in conjunction with transurethral resection of bladder tumour (TURBT). Two review authors independently screened the literature, extracted data, assessed risk of bias and rated quality of evidence (QoE) according to GRADE on a per outcome basis. We included three trials with 672 participants that described five distinct comparisons. The same principal investigator conducted all three trials. All studies used mitomycin C (MMC) as the chemotherapeutic agent for EMDA. 1. Postoperative MMC-EMDA induction versus postoperative Bacillus Calmette-Guérin (BCG) induction: based on one study with 72 participants with carcinoma in situ (CIS) and concurrent pT1 urothelial carcinoma, we are uncertain (very low QoE) about the effect of MMC-EMDA on time to recurrence (risk ratio (RR) 1.06, 95% confidence interval (CI) 0.64 to 1.76; corresponding to 30 more per 1000 participants, 95% CI 180 fewer to 380 more). There was no disease progression in either treatment arm at three months' follow-up. We are uncertain (very low QoE) about serious adverse events (RR 0.75, 95% CI 0.18 to 3.11). 2. Postoperative MMC-EMDA induction versus MMC-passive diffusion (PD) induction: based on one study with 72

  9. Multiwire proportional chamber development

    NASA Technical Reports Server (NTRS)

    Doolittle, R. F.; Pollvogt, U.; Eskovitz, A. J.

    1973-01-01

    The development of large area multiwire proportional chambers, to be used as high resolution spatial detectors in cosmic ray experiments is described. A readout system was developed which uses a directly coupled, lumped element delay-line whose characteristics are independent of the MWPC design. A complete analysis of the delay-line and the readout electronic system shows that a spatial resolution of about 0.1 mm can be reached with the MWPC operating in the strictly proportional region. This was confirmed by measurements with a small MWPC and Fe-55 X-rays. A simplified analysis was carried out to estimate the theoretical limit of spatial resolution due to delta-rays, spread of the discharge along the anode wire, and inclined trajectories. To calculate the gas gain of MWPC's of different geometrical configurations a method was developed which is based on the knowledge of the first Townsend coefficient of the chamber gas.

  10. Proportional counter radiation camera

    DOEpatents

    Borkowski, C.J.; Kopp, M.K.

    1974-01-15

    A gas-filled proportional counter camera that images photon emitting sources is described. A two-dimensional, positionsensitive proportional multiwire counter is provided as the detector. The counter consists of a high- voltage anode screen sandwiched between orthogonally disposed planar arrays of multiple parallel strung, resistively coupled cathode wires. Two terminals from each of the cathode arrays are connected to separate timing circuitry to obtain separate X and Y coordinate signal values from pulse shape measurements to define the position of an event within the counter arrays which may be recorded by various means for data display. The counter is further provided with a linear drift field which effectively enlarges the active gas volume of the counter and constrains the recoil electrons produced from ionizing radiation entering the counter to drift perpendicularly toward the planar detection arrays. A collimator is interposed between a subject to be imaged and the counter to transmit only the radiation from the subject which has a perpendicular trajectory with respect to the planar cathode arrays of the detector. (Official Gazette)

  11. The microstrip proportional counter

    NASA Technical Reports Server (NTRS)

    Ramsey, B. D.

    1992-01-01

    Microstrip detectors in which the usual discrete anode and cathode wires are replaced by conducting strips on an insulating or partially insulating substrate are fabricated using integrated circuit-type photolithographic techniques and hence offer very high spatial accuracy and uniformity, together with the capability of producing extremely fine electrode structures. Microstrip proportional counters have now been variously reported having an energy resolution of better than 11 percent FWHM at 5.9 keV. They have been fabricated with anode bars down to 2 microns and on a variety of substrate materials including thin films which can be molded to different shapes. This review will examine the development of the microstrip detector with emphasis on the qualities which make this detector particularly interesting for use in astronomy.

  12. Gated strip proportional detector

    DOEpatents

    Morris, Christopher L.; Idzorek, George C.; Atencio, Leroy G.

    1987-01-01

    A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10.sup.6. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

  13. Gated strip proportional detector

    DOEpatents

    Morris, C.L.; Idzorek, G.C.; Atencio, L.G.

    1985-02-19

    A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10/sup 6/. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

  14. Lorentz Force on Sodium and Chlorine Ions in a Salt Water Solution Flow under a Transverse Magnetic Field

    ERIC Educational Resources Information Center

    De Luca, R.

    2009-01-01

    It is shown that, by applying elementary concepts in electromagnetism and electrochemistry to a system consisting of salt water flowing in a thin rectangular pipe at an average velocity v[subscript A] under the influence of a transverse magnetic field B[subscript 0], an electromotive force generator can be conceived. In fact, the Lorentz force…

  15. Lorentz Force on Sodium and Chlorine Ions in a Salt Water Solution Flow under a Transverse Magnetic Field

    ERIC Educational Resources Information Center

    De Luca, R.

    2009-01-01

    It is shown that, by applying elementary concepts in electromagnetism and electrochemistry to a system consisting of salt water flowing in a thin rectangular pipe at an average velocity v[subscript A] under the influence of a transverse magnetic field B[subscript 0], an electromotive force generator can be conceived. In fact, the Lorentz force…

  16. Visual Manipulatives for Proportional Reasoning.

    ERIC Educational Resources Information Center

    Moore, Joyce L.; Schwartz, Daniel L.

    The use of a visual representation in learning about proportional relations was studied, examining students' understandings of the invariance of a multiplicative relation on both sides of a proportion equation and the invariance of the structural relations that exist in different semantic types of proportion problems. Subjects were 49 high-ability…

  17. Equation-of-motion approach of spin-motive force

    SciTech Connect

    Yamane, Yuta; Ieda, Jun'ichi; Ohe, Jun-ichiro; Maekawa, Sadamichi; Barnes, Stewart E.

    2011-04-01

    We formulate a quantitative theory of an electromotive force of spin origin, i.e., spin-motive force, by the equation-of-motion approach. In a ferromagnetic metal, electrons couple to the local magnetization via the exchange interaction. The electrons are affected by spin dependent forces due to this interaction and the spin-motive force and the anomalous Hall effect appears. We have revealed that the origin of these phenomena is a misalignment between the conduction electron spin and the local magnetization.

  18. Proportional Reasoning as Essential Numeracy

    ERIC Educational Resources Information Center

    Dole, Shelley; Hilton, Annette; Hilton, Geoff

    2015-01-01

    This paper reports an aspect of a large research and development project that aimed to promote middle years school teachers' understanding and awareness of the pervasiveness of proportional reasoning as integral to numeracy. Teacher survey data of proportional reasoning across the curriculum were mapped on to a rich model of numeracy. Results…

  19. Multiple Ways to Solve Proportions

    ERIC Educational Resources Information Center

    Ercole, Leslie K.; Frantz, Marny; Ashline, George

    2011-01-01

    When solving problems involving proportions, students may intuitively draw on strategies that connect to their understanding of fractions, decimals, and percents. These two statements--"Instruction in solving proportions should include methods that have a strong intuitive basis" and "Teachers should begin instruction with more intuitive…

  20. Multiple Ways to Solve Proportions

    ERIC Educational Resources Information Center

    Ercole, Leslie K.; Frantz, Marny; Ashline, George

    2011-01-01

    When solving problems involving proportions, students may intuitively draw on strategies that connect to their understanding of fractions, decimals, and percents. These two statements--"Instruction in solving proportions should include methods that have a strong intuitive basis" and "Teachers should begin instruction with more intuitive…

  1. Testing proportionality in the proportional odds model fitted with GEE.

    PubMed

    Stiger, T R; Barnhart, H X; Williamson, J M

    1999-06-15

    Generalized estimating equations (GEE) methodology as proposed by Liang and Zeger has received widespread use in the analysis of correlated binary data. Miller et al. and Lipsitz et al. extended GEE to correlated nominal and ordinal categorical data; in particular, they used GEE for fitting McCullagh's proportional odds model. In this paper, we consider robust (that is, empirically corrected) and model-based versions of both a score test and a Wald test for assessing the assumption of proportional odds in the proportional odds model fitted with GEE. The Wald test is based on fitting separate multiple logistic regression models for each dichotomization of the response variable, whereas the score test requires fitting just the proportional odds model. We evaluate the proposed tests in small to moderate samples by simulating data from a series of simple models. We illustrate the use of the tests on three data sets from medical studies.

  2. Proportional smile design using the recurring esthetic dental (red) proportion.

    PubMed

    Ward, D H

    2001-01-01

    Dentists have needed an objective way in which to evaluate a smile. A method for determining the ideal size and position of the anterior teeth has been presented here. Use of the FIVE to evaluate the RED proportion and the width-to-height ratio, tempered with sound clinical judgment, gives pleasing and consistent results. With the diversity that exists in nature, rarely does the final result follow all the mathematical rules of proportional smile design. This approach may serve as a foundation on which to base initial smile design, however. When one begins to understand the relationship between beauty, mathematics, and the surrounding world, one begins to appreciate their interdependence.

  3. Bayesian Inference on Proportional Elections

    PubMed Central

    Brunello, Gabriel Hideki Vatanabe; Nakano, Eduardo Yoshio

    2015-01-01

    Polls for majoritarian voting systems usually show estimates of the percentage of votes for each candidate. However, proportional vote systems do not necessarily guarantee the candidate with the most percentage of votes will be elected. Thus, traditional methods used in majoritarian elections cannot be applied on proportional elections. In this context, the purpose of this paper was to perform a Bayesian inference on proportional elections considering the Brazilian system of seats distribution. More specifically, a methodology to answer the probability that a given party will have representation on the chamber of deputies was developed. Inferences were made on a Bayesian scenario using the Monte Carlo simulation technique, and the developed methodology was applied on data from the Brazilian elections for Members of the Legislative Assembly and Federal Chamber of Deputies in 2010. A performance rate was also presented to evaluate the efficiency of the methodology. Calculations and simulations were carried out using the free R statistical software. PMID:25786259

  4. Saving Money Using Proportional Reasoning

    ERIC Educational Resources Information Center

    de la Cruz, Jessica A.; Garney, Sandra

    2016-01-01

    It is beneficial for students to discover intuitive strategies, as opposed to the teacher presenting strategies to them. Certain proportional reasoning tasks are more likely to elicit intuitive strategies than other tasks. The strategies that students are apt to use when approaching a task, as well as the likelihood of a student's success or…

  5. Proportional Hazards Models of Graduation

    ERIC Educational Resources Information Center

    Chimka, Justin R.; Reed-Rhoads, Teri; Barker, Kash

    2008-01-01

    Survival analysis is a statistical tool used to describe the duration between events. Many processes in medical research, engineering, and economics can be described using survival analysis techniques. This research involves studying engineering college student graduation using Cox proportional hazards models. Among male students with American…

  6. Proportional Reasoning with a Pyramid

    ERIC Educational Resources Information Center

    Mamolo, Ami; Sinclair, Margaret; Whiteley, Walter J.

    2011-01-01

    Proportional reasoning pops up in math class in a variety of places, such as while making scaled drawings; finding equivalent fractions; converting units of measurement; comparing speeds, prices, and rates; and comparing lengths, areas, and volume. Students need to be exposed to a variety of representations to develop a sound understanding of this…

  7. Proportional Reasoning with a Pyramid

    ERIC Educational Resources Information Center

    Mamolo, Ami; Sinclair, Margaret; Whiteley, Walter J.

    2011-01-01

    Proportional reasoning pops up in math class in a variety of places, such as while making scaled drawings; finding equivalent fractions; converting units of measurement; comparing speeds, prices, and rates; and comparing lengths, areas, and volume. Students need to be exposed to a variety of representations to develop a sound understanding of this…

  8. Saving Money Using Proportional Reasoning

    ERIC Educational Resources Information Center

    de la Cruz, Jessica A.; Garney, Sandra

    2016-01-01

    It is beneficial for students to discover intuitive strategies, as opposed to the teacher presenting strategies to them. Certain proportional reasoning tasks are more likely to elicit intuitive strategies than other tasks. The strategies that students are apt to use when approaching a task, as well as the likelihood of a student's success or…

  9. Social Justice and Proportional Reasoning

    ERIC Educational Resources Information Center

    Simic-Muller, Ksenija

    2015-01-01

    Ratio and proportional reasoning tasks abound that have connections to real-world situations. Examples in this article demonstrate how textbook tasks can easily be transformed into authentic real-world problems that shed light on issues of equity and fairness, such as population growth and crime rates. A few ideas are presented on how teachers can…

  10. A method for estimating proportions

    NASA Technical Reports Server (NTRS)

    Guseman, L. F., Jr.; Marion, B. P.

    1975-01-01

    A proportion estimation procedure is presented which requires only on set of ground truth data for determining the error matrix. The error matrix is then used to determine an unbiased estimate. The error matrix is shown to be directly related to the probability of misclassifications, and is more diagonally dominant with the increase in the number of passes used.

  11. Proportional Hazards Models of Graduation

    ERIC Educational Resources Information Center

    Chimka, Justin R.; Reed-Rhoads, Teri; Barker, Kash

    2008-01-01

    Survival analysis is a statistical tool used to describe the duration between events. Many processes in medical research, engineering, and economics can be described using survival analysis techniques. This research involves studying engineering college student graduation using Cox proportional hazards models. Among male students with American…

  12. Understanding Proportional Reasoning for Teaching

    ERIC Educational Resources Information Center

    Kastberg, Signe E.; D'Ambrosio, Beatriz; Lynch-Davis, Kathleen

    2012-01-01

    Proportional reasoning is an important cornerstone in children's mathematical development. This sort of reasoning has been shown to develop across the early years of schooling (ages 8 to 10) through the middle years (ages 11-14). In the early years, children tend to use additive reasoning to generate solutions to problems, while later comparisons…

  13. Social Justice and Proportional Reasoning

    ERIC Educational Resources Information Center

    Simic-Muller, Ksenija

    2015-01-01

    Ratio and proportional reasoning tasks abound that have connections to real-world situations. Examples in this article demonstrate how textbook tasks can easily be transformed into authentic real-world problems that shed light on issues of equity and fairness, such as population growth and crime rates. A few ideas are presented on how teachers can…

  14. [Invariants of the anthropometrical proportions].

    PubMed

    Smolianinov, V V

    2012-01-01

    In this work a general interpretation of a modulor as scales of segments proportions of anthropometrical modules (extremities and a body) is made. The objects of this study were: 1) to reason the idea of the growth modulor; 2) using the modern empirical data, to prove the validity of a principle of linear similarity for anthropometrical segments; 3) to specify the system of invariants for constitutional anthropometrics.

  15. Metacarpal proportions in Australopithecus africanus.

    PubMed

    Green, David J; Gordon, Adam D

    2008-05-01

    Recent work has shown that, despite being craniodentally more derived, Australopithecus africanus had more apelike limb-size proportions than A. afarensis. Here, we test whether the A. africanus hand, as judged by metacarpal shaft and articular proportions, was similarly apelike. More specifically, did A. africanus have a short and narrow first metacarpal (MC1) relative to the other metacarpals? Proportions of both MC breadth and length were considered: the geometric mean (GM) of articular and midshaft measurements of MC1 breadth was compared to those of MC2-4, and MC1 length was compared to MC3 length individually and also to the GM of MC2 and 3 lengths. To compare the extant hominoid sample with an incomplete A. africanus fossil record (11 attributed metacarpals), a resampling procedure imposed sampling constraints on the comparative groups that produced composite intrahand ratios. Resampled ratios in the extant sample are not significantly different from actual ratios based on associated elements, demonstrating the methodological appropriateness of this technique. Australopithecus africanus metacarpals do not differ significantly from the great apes in the comparison of breadth ratios but are significantly greater than chimpanzees and orangutans in both measures of relative length. Conversely, A. africanus has a significantly smaller breadth ratio than modern humans, but does not significantly differ from this group in either measure of relative length. We conclude that the first metacarpals of A. africanus are more apelike in relative breadth while also being more humanlike in relative length, a finding consistent with previous work on A. afarensis hand proportions. This configuration would have likely promoted a high degree of manipulative dexterity, but the relatively slender, apelike first metacarpal suggests that A. africanus did not place the same mechanical demands on the thumb as more recent, stone-tool-producing hominins.

  16. Photodetectors for Scintillator Proportionality Measurement

    SciTech Connect

    Moses, William W.; Choong, Woon-Seng; Hull, Giulia; Payne, Steve; Cherepy, Nerine; Valentine, J.D.

    2010-10-18

    We evaluate photodetectors for use in a Compton Coincidence apparatus designed for measuring scintillator proportionality. There are many requirements placed on the photodetector in these systems, including active area, linearity, and the ability to accurately measure low light levels (which implies high quantum efficiency and high signal-to-noise ratio). Through a combination of measurement and Monte Carlo simulation, we evaluate a number of potential photodetectors, especially photomultiplier tubes and hybrid photodetectors. Of these, we find that the most promising devices available are photomultiplier tubes with high ({approx}50%) quantum efficiency, although hybrid photodetectors with high quantum efficiency would be preferable.

  17. Incisors’ proportions in smile esthetics

    PubMed Central

    Alsulaimani, Fahad F; Batwa, Waeil

    2013-01-01

    Aims: To determine whether alteration of the maxillary central and lateral incisors’ length and width, respectively, would affect perceived smile esthetics and to validate the most esthetic length and width, respectively, for the central and lateral incisors. Materials and Methods: Photographic manipulation was undertaken to produce two sets of photographs, each set of four photographs showing the altered width of the lateral incisor and length of the central length. The eight produced photographs were assessed by laypeople, dentists and orthodontists. Results: Alteration in the incisors’ proportion affected the relative smile attractiveness for laypeople (n=124), dentists (n=115) and orthodontists (n=68); dentists and orthodontists did not accept lateral width reduction of more than 0.5 mm (P<0.01), which suggests that the lateral to central incisor width ratio ranges from 54% to 62%. However, laypeople did not accept lateral width reduction of more than 1 mm (P<0.01), widening the range to be from 48% to 62%. All groups had zero tolerance for changes in central crown length (P<0.01). Conclusion: All participants recognized that the central incisors’ length changes. For lateral incisors, laypeople were more tolerant than dentists and orthodontists. This suggests that changing incisors’ proportions affects the relative smile attractiveness. PMID:24987650

  18. Active vibration isolation by adaptive proportional control

    NASA Astrophysics Data System (ADS)

    Liu, Yun-Hui; Wu, Wei-Hao; Chu, Chih-Liang

    2013-01-01

    An active vibration isolation system that applies proportional controller incorporated with an adaptive filter to reduce the transmission of base excitations to a precision instrument is proposed in this work. The absolute vibration velocity signal acquired from an accelerator and being processed through an integrator is input to the controller as a feedback signal, and the controller output signal drives the voice coil actuator to produce a sky-hook damper force. In practice, the phase response of integrator at low frequency such as 2~5 Hz deviate from the 90 degree which is the exact phase difference between the vibration velocity and acceleration. Therefore, an adaptive filter is used to compensate the phase error in this paper. An analysis of this active vibration isolation system is presented, and model predictions are compared to experimental results. The results show that the proposed method significantly reduces transmissibility at resonance without the penalty of increased transmissibility at higher frequencies.

  19. Proportional Reasoning: A Review of the Literature.

    ERIC Educational Resources Information Center

    Tourniaire, Francoise; Pulos, Steven

    1985-01-01

    The literature on proportional reasoning is reviewed. After methodology is discussed, strategies used to solve proportion problems, variables that influence performance, and training studies are each considered. (MNS)

  20. Proportional feedback control of flow over a hemisphere

    NASA Astrophysics Data System (ADS)

    Lee, Jungil; Yun, Jinhyuk; Son, Donggun

    2016-11-01

    In the present study, a proportional feedback control is applied to laminar flow over a hemisphere at Re = 300 to reduce its lift fluctuations. As a control input, blowing/suction is distributed on the surface of hemisphere before the separation, and its strength is linearly proportional to the transverse velocity at a sensing location in the centerline of the wake. To determine the optimal sensing location, we introduce a correlation function between the lift force and the time derivative of sensing velocity. The optimal proportional gains for the proportional control are obtained for the sensing locations considered. It is shown that the present control successfully attenuates the velocity fluctuations at the sensing location, resulting in the reduction of lift fluctuations of hemisphere. Supported by NRF program (2014R1A1A1002671).

  1. Cognitive and Metacognitive Aspects of Proportional Reasoning

    ERIC Educational Resources Information Center

    Modestou, Modestina; Gagatsis, Athanasios

    2010-01-01

    In this study we attempt to propose a new model of proportional reasoning based both on bibliographical and research data. This is impelled with the help of three written tests involving analogical, proportional, and non-proportional situations that were administered to pupils from grade 7 to 9. The results suggest the existence of a…

  2. Body proportions in children with Kabuki syndrome.

    PubMed

    Penders, Bas; Schott, Nina; Gerver, Willem-Jan M; Stumpel, Constance T R M

    2016-03-01

    Facial characteristics, short stature, and skeletal anomalies have been described for the clinical diagnosis of Kabuki Syndrome (KS) in children. However, no studies have investigated body proportions in KS. Knowledge of body proportions in KS may contribute to better insight into the growth pattern and characterization of this genetic disorder. Therefore we compared body proportions of children with KS to normally proportioned controls to investigate if atypical body proportions are part of this genetic disorder. This study was designed and conducted within the setting of the Maastricht University Medical Centre (MUMC+), the official Dutch expert center for Kabuki syndrome. We conducted a cross-sectional study in 32 children (11 children with KS and 21 controls). Body proportions were determined by means of photogrammetric anthropometry, measurements based on digital photography. Body proportions, quantified as body ratios, differ significantly in children with KS from normally proportioned children. Children with KS have larger heads and longer arms proportional to their trunks and have been found to have longer upper arms proportional to their tibia length and feet. Based on deviations in body proportions it was shown possible to discern children with KS from normally proportioned controls.

  3. Evaluating Middle Years Students' Proportional Reasoning

    ERIC Educational Resources Information Center

    Hilton, Annette; Dole, Shelley; Hilton, Geoff; Goos, Merrilyn; O'Brien, Mia

    2012-01-01

    Proportional reasoning is a key aspect of numeracy that is not always developed naturally by students. Understanding the types of proportional reasoning that students apply to different problem types is a useful first step to identifying ways to support teachers and students to develop proportional reasoning in the classroom. This paper describes…

  4. Cognitive and Metacognitive Aspects of Proportional Reasoning

    ERIC Educational Resources Information Center

    Modestou, Modestina; Gagatsis, Athanasios

    2010-01-01

    In this study we attempt to propose a new model of proportional reasoning based both on bibliographical and research data. This is impelled with the help of three written tests involving analogical, proportional, and non-proportional situations that were administered to pupils from grade 7 to 9. The results suggest the existence of a…

  5. Estimating proportions of materials using mixture models

    NASA Technical Reports Server (NTRS)

    Heydorn, R. P.; Basu, R.

    1983-01-01

    An approach to proportion estimation based on the notion of a mixture model, appropriate parametric forms for a mixture model that appears to fit observed remotely sensed data, methods for estimating the parameters in these models, methods for labelling proportion determination from the mixture model, and methods which use the mixture model estimates as auxiliary variable values in some proportion estimation schemes are addressed.

  6. Fluid-dynamic design optimization of hydraulic proportional directional valves

    NASA Astrophysics Data System (ADS)

    Amirante, Riccardo; Catalano, Luciano Andrea; Poloni, Carlo; Tamburrano, Paolo

    2014-10-01

    This article proposes an effective methodology for the fluid-dynamic design optimization of the sliding spool of a hydraulic proportional directional valve: the goal is the minimization of the flow force at a prescribed flow rate, so as to reduce the required opening force while keeping the operation features unchanged. A full three-dimensional model of the flow field within the valve is employed to accurately predict the flow force acting on the spool. A theoretical analysis, based on both the axial momentum equation and flow simulations, is conducted to define the design parameters, which need to be properly selected in order to reduce the flow force without significantly affecting the flow rate. A genetic algorithm, coupled with a computational fluid dynamics flow solver, is employed to minimize the flow force acting on the valve spool at the maximum opening. A comparison with a typical single-objective optimization algorithm is performed to evaluate performance and effectiveness of the employed genetic algorithm. The optimized spool develops a maximum flow force which is smaller than that produced by the commercially available valve, mainly due to some major modifications occurring in the discharge section. Reducing the flow force and thus the electromagnetic force exerted by the solenoid actuators allows the operational range of direct (single-stage) driven valves to be enlarged.

  7. Proportional valve with a piezoelectric actuator

    NASA Astrophysics Data System (ADS)

    Laski, Pawel Andrzej

    The article concerns a slotted proportional valve for use in pneumatic and hydraulic systems. There is a growing demand for both hydraulic and pneumatic ultrafast proportional valves. The conducted analysis of literature confirms the lack of such solutions for proportional valves. The currently used pneumatic systems for selection and segregation of parts and objects require ultrafast valves. The presented solution for the proportional valve can significantly improve and accelerate this type of technological processes. Furthermore, fast proportional valves can be successfully used for positional control of pneumatic and hydraulic drives. The article presents the design of a slotted divide valve and sets the maximum mass flow rate for service roads.

  8. Proportional valve with a piezoelectric actuator

    NASA Astrophysics Data System (ADS)

    Laski, Pawel Andrzej

    2016-11-01

    The article concerns a slotted proportional valve for use in pneumatic and hydraulic systems. There is a growing demand for both hydraulic and pneumatic ultrafast proportional valves. The conducted analysis of literature confirms the lack of such solutions for proportional valves. The currently used pneumatic systems for selection and segregation of parts and objects require ultrafast valves. The presented solution for the proportional valve can significantly improve and accelerate this type of technological processes. Furthermore, fast proportional valves can be successfully used for positional control of pneumatic and hydraulic drives. The article presents the design of a slotted divide valve and sets the maximum mass flow rate for service roads.

  9. Tree-augmented Cox proportional hazards models.

    PubMed

    Su, Xiaogang; Tsai, Chih-Ling

    2005-07-01

    We study a hybrid model that combines Cox proportional hazards regression with tree-structured modeling. The main idea is to use step functions, provided by a tree structure, to 'augment' Cox (1972) proportional hazards models. The proposed model not only provides a natural assessment of the adequacy of the Cox proportional hazards model but also improves its model fitting without loss of interpretability. Both simulations and an empirical example are provided to illustrate the use of the proposed method.

  10. CCSSM Challenge: Graphing Ratio and Proportion

    ERIC Educational Resources Information Center

    Kastberg, Signe E.; D'Ambrosio, Beatriz S.; Lynch-Davis, Kathleen; Mintos, Alexia; Krawczyk, Kathryn

    2013-01-01

    A renewed emphasis was placed on ratio and proportional reasoning in the middle grades in the Common Core State Standards for Mathematics (CCSSM). The expectation for students includes the ability to not only compute and then compare and interpret the results of computations in context but also interpret ratios and proportions as they are…

  11. Working Memory Mechanism in Proportional Quantifier Verification

    ERIC Educational Resources Information Center

    Zajenkowski, Marcin; Szymanik, Jakub; Garraffa, Maria

    2014-01-01

    The paper explores the cognitive mechanisms involved in the verification of sentences with proportional quantifiers (e.g. "More than half of the dots are blue"). The first study shows that the verification of proportional sentences is more demanding than the verification of sentences such as: "There are seven blue and eight yellow…

  12. Prospective Elementary School Teachers' Proportional Reasoning

    ERIC Educational Resources Information Center

    Valverde, Gabriela; Castro, Encarnación

    2012-01-01

    We present the findings of a study on prospective elementary teachers' proportional reasoning. After describing some of the teachers' performance in solving multiplicative structure problems that involve ratios and relations of direct proportionality between quantities, we were able to establish classifications of their answers according to…

  13. Examining Prospective Teachers' Understanding of Proportional Reasoning

    ERIC Educational Resources Information Center

    Kitchen, Richard; DePree, Julie

    2004-01-01

    In this article, the authors describe their efforts to assess prospective K-8 teachers' knowledge of proportional reasoning. Based upon their analysis of prospective K-8 teachers' work on a mathematics performance task, they discuss the implications for preparing prospective teachers to teach proportional reasoning to their students. In general,…

  14. Estimating crop proportions from remotely sensed data

    NASA Technical Reports Server (NTRS)

    Feiveson, A. H. (Principal Investigator)

    1979-01-01

    The classification/pixel-count method for estimating the proportion of wheat in each segment is theoretically biased even if all distributional assumptions are met. Alternative ways to estimate crop proportions are examined and their performance testing is considered. Topics covered include general linear functional estimates, the method of moments, and maximum likelihood estimators.

  15. Working Memory Mechanism in Proportional Quantifier Verification

    ERIC Educational Resources Information Center

    Zajenkowski, Marcin; Szymanik, Jakub; Garraffa, Maria

    2014-01-01

    The paper explores the cognitive mechanisms involved in the verification of sentences with proportional quantifiers (e.g. "More than half of the dots are blue"). The first study shows that the verification of proportional sentences is more demanding than the verification of sentences such as: "There are seven blue and eight yellow…

  16. CCSSM Challenge: Graphing Ratio and Proportion

    ERIC Educational Resources Information Center

    Kastberg, Signe E.; D'Ambrosio, Beatriz S.; Lynch-Davis, Kathleen; Mintos, Alexia; Krawczyk, Kathryn

    2013-01-01

    A renewed emphasis was placed on ratio and proportional reasoning in the middle grades in the Common Core State Standards for Mathematics (CCSSM). The expectation for students includes the ability to not only compute and then compare and interpret the results of computations in context but also interpret ratios and proportions as they are…

  17. Proportional Reasoning and the Visually Impaired

    ERIC Educational Resources Information Center

    Hilton, Geoff; Hilton, Annette; Dole, Shelley L.; Goos, Merrilyn; O'Brien, Mia

    2012-01-01

    Proportional reasoning is an important aspect of formal thinking that is acquired during the developmental years that approximate the middle years of schooling. Students who fail to acquire sound proportional reasoning often experience difficulties in subjects that require quantitative thinking, such as science, technology, engineering, and…

  18. Numerical Proportion Representation: A Neurocomputational Account.

    PubMed

    Chen, Qi; Verguts, Tom

    2017-01-01

    Proportion representation is an emerging subdomain in numerical cognition. However, its nature and its correlation with simple number representation remain elusive, especially at the theoretical level. To fill this gap, we propose a gain-field model of proportion representation to shed light on the neural and computational basis of proportion representation. The model is based on two well-supported neuroscientific findings. The first, gain modulation, is a general mechanism for information integration in the brain; the second relevant finding is how simple quantity is neurally represented. Based on these principles, the model accounts for recent relevant proportion representation data at both behavioral and neural levels. The model further addresses two key computational problems for the cognitive processing of proportions: invariance and generalization. Finally, the model provides pointers for future empirical testing.

  19. A likelihood ratio test for nested proportions.

    PubMed

    Chen, Yi-Fan; Yabes, Jonathan G; Brooks, Maria M; Singh, Sonia; Weissfeld, Lisa A

    2015-02-10

    For policy and medical issues, it is important to know if the proportion of an event changes after an intervention is administered. When the later proportion can only be calculated in a portion of the sample used to compute the previous proportion, the two proportions are nested. The motivating example for this work comes from the need to test whether admission rates in emergency departments are different between the first and a return visit. Here, subjects who contribute to the admission rate at the return visit must be included in the first rate and also return, but not vice versa. This conditionality means that existing methods, including the basic test of equality of two proportions, longitudinal data analysis methods, and recurrent event approaches are not directly applicable. Currently, researchers can only explore this question by the use of descriptive statistics. We propose a likelihood ratio test to compare two nested proportions by using the product of conditional probabilities. This test accommodates the conditionality, subject dependencies, and cluster effects and can be implemented in SAS PROC NLMIXED allowing for the proposed method to be readily used in an applied setting. Simulation studies showed that our approach provides unbiased estimates and reasonable power. Moreover, it generally outperforms the two-sample proportion z-test, in the presence of heterogeneity, and the Cochran-Mantel-Haenszel test. An example based on readmission rates through an emergency department is used to illustrate the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.

  20. Proportion of recovered waterfowl bands reported

    USGS Publications Warehouse

    Geis, A.D.; Atwood, E.L.

    1961-01-01

    Data from the annual mail survey of waterfowl hunters in the United States were used to estimate the total numbers of banded waterfowl that were shot. These estimates were compared with Banding Office records to estimate the proportion of recovered bands that was reported. On the average, about two banded birds were recovered for each one reported. The proportion reported was higher for some areas and for some species than for others. The proportion reported was higher when more of the reports came through employees of conservation agencies.

  1. Leg length, proportion, health and beauty: a review.

    PubMed

    Bogin, Barry; Varela-Silva, Maria Inês

    2009-12-01

    Decomposing stature into its major components is proving to be a useful strategy to assess the antecedents of disease, morbidity and death in adulthood. Human leg length (foot + tibia + femur), sitting height (trunk length + head length) and their proportions (for example the relative leg length in proportion to stature, and the sitting height ratio [sitting height/stature x 100], among others) are used as epidemiological markers of risk for overweight (fatness), coronary heart disease, diabetes and certain cancers. There is also wide support for the use of relative leg length as an indicator of the quality of the environment for growth during infancy, childhood and the juvenile years of development. Human beings follow a cephalo-caudal gradient of growth, the pattern of growth common to all mammals. A special feature of the human pattern is that between birth and puberty the legs grow relatively faster than other post-cranial body segments. For groups of children and youth, short stature due to relatively short legs (i.e. a high sitting height ratio) is generally a marker of an adverse environment. The development of human body proportions is the product of environmental x genomic interactions, although few if any specific genes are known. The short stature homeobox-containing gene (SHOX) is the first genomic region that may be relevant to human body proportions. For example, one of the SHOX related disorders is Turner syndrome. However, in most cases research has been showing that environment is a more powerful force to shape leg length and body proportions than genes. Leg length and proportion are important in the perception of human beauty, which is often considered a sign of health and fertility. There are a variety of cosmetic, fashion, and surgical interventions to enhance perceived or actual leg length.

  2. Proportion estimation using prior cluster purities

    NASA Technical Reports Server (NTRS)

    Terrell, G. R. (Principal Investigator)

    1980-01-01

    The prior distribution of CLASSY component purities is studied, and this information incorporated into maximum likelihood crop proportion estimators. The method is tested on Transition Year spring small grain segments.

  3. Proportionality, just war theory and weapons innovation.

    PubMed

    Forge, John

    2009-03-01

    Just wars are supposed to be proportional responses to aggression: the costs of war must not greatly exceed the benefits. This proportionality principle raises a corresponding 'interpretation problem': what are the costs and benefits of war, how are they to be determined, and a 'measurement problem': how are costs and benefits to be balanced? And it raises a problem about scope: how far into the future do the states of affairs to be measured stretch? It is argued here that weapons innovation always introduces costs, and that these costs cannot be determined in advance of going to war. Three examples, the atomic bomb, the AK-47 and the ancient Greek catapult, are given as examples. It is therefore argued that the proportionality principle is inapplicable prospectively. Some replies to the argument are discussed and rejected. Some more general defences of the proportionality principle are considered and also rejected. Finally, the significance of the argument for Just War Theory as a whole is discussed.

  4. Using Resampling to Compare Two Proportions

    ERIC Educational Resources Information Center

    Stephenson, W. Robert; Froelich, Amy G.; Duckworth, William M.

    2010-01-01

    This article shows that when applying resampling methods to the problem of comparing two proportions, students can discover that whether you resample with or without replacement can make a big difference.

  5. Using Resampling to Compare Two Proportions

    ERIC Educational Resources Information Center

    Stephenson, W. Robert; Froelich, Amy G.; Duckworth, William M.

    2010-01-01

    This article shows that when applying resampling methods to the problem of comparing two proportions, students can discover that whether you resample with or without replacement can make a big difference.

  6. Whither the "signature wounds of the war" after the war: estimates of incidence rates and proportions of TBI and PTSD diagnoses attributable to background risk, enhanced ascertainment, and active war zone service, active component, U.S. Armed Forces, 2003-2014.

    PubMed

    Brundage, John F; Taubman, Stephen B; Hunt, Devin J; Clark, Leslie L

    2015-02-01

    Traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD) are "signature wounds" of the Afghanistan/Iraq wars; however, many TBI/PTSD cases are not war related. During the wars, diagnoses of TBI/PTSD among military members increased because risks of TBI/PTSD, and capabilities to detect cases, increased. This report summarizes TBI/PTSD diagnosis experiences of three cohorts of overseas deployers in relation to the natures of their exposures to active war service and enhanced case ascertainment efforts. The findings suggest that, during the war, the proportions of PTSD diagnoses attributable to war zone service decreased from approximately 80% to less than 50%, while the proportions attributable to enhanced case ascertainment increased from less than 10% to nearly 50%. The proportions of TBI diagnoses attributable to war zone service more than tripled from 2003-2005 (13.1%) through 2007-2009 (44.8%); the proportions attributable to enhanced ascertainment also markedly increased, but not until after 2007. By the end of the war, war zone service and enhanced ascertainment accounted for similar proportions of all PTSD and TBI diagnoses. If programs and resources currently focused on TBI and PTSD continue, rates of diagnoses post-war will greatly exceed those pre-war.

  7. Lathe tool force

    SciTech Connect

    Emery, J.D.

    1993-02-01

    This report describes a computer program that computes the forces exerted on a lathe tool as a part is being machined. The program is based on a mechanistic model which assumes that the normal force on the tool face is proportional to the cross-sectional area of the chip that is being removed from the part. This report gives transcripts of program runs, a comparison with experimentally measured forces, a bibliography, and a listing of the program.

  8. Testing departure from Hardy-Weinberg proportions.

    PubMed

    Wang, Jian; Shete, Sanjay

    2012-01-01

    The Hardy-Weinberg principle, one of the most important principles in population genetics, was originally developed for the study of allele frequency changes in a population over generations. It is now, however, widely used in studies of human diseases to detect inbreeding, populations stratification, and genotyping errors. For assessment of deviation from the Hardy-Weinberg proportions in data, the most popular approaches include the asymptotic Pearson's chi-square goodness-of-fit test and the exact test. The Pearson's chi-square goodness-of-fit test is simple and straightforward, but it is very sensitive to small sample size or rare allele frequency. The exact test of Hardy-Weinberg proportions is preferable in these situations. The exact test can be performed through complete enumeration of heterozygote genotypes or on the basis of the Markov chain Monte Carlo procedure. In this chapter, we describe the Hardy-Weinberg principle and the commonly used Hardy-Weinberg proportions tests and their applications, and we demonstrate how the chi-square test and exact test of Hardy-Weinberg proportions can be performed step-by-step using the popular software programs SAS, R, and PLINK, which have been widely used in genetic association studies, along with numerical examples. We also discuss recent approaches for testing Hardy-Weinberg proportions in case-control study designs that are better than traditional approaches for testing Hardy-Weinberg proportions in controls only. Finally, we note that deviation from the Hardy-Weinberg proportions in affected individuals can provide evidence for an association between genetic variants and diseases.

  9. Reassessing manual proportions in Australopithecus afarensis.

    PubMed

    Rolian, Campbell; Gordon, Adam D

    2013-11-01

    Previous analyses of hand morphology in Australopithecus afarensis have concluded that this taxon had modern human-like manual proportions, with relatively long thumbs and short fingers. These conclusions are based on the A.L.333 composite fossil assemblage from Hadar, Ethiopia, and are premised on the ability to assign phalanges to a single individual, and to the correct side and digit. Neither assignment is secure, however, given the taphonomy and sample composition at A.L.333. We use a resampling approach that includes the entire assemblage of complete hand elements at Hadar, and takes into account uncertainties in identifying phalanges by individual, side and digit number. This approach provides the most conservative estimates of manual proportions in Au. afarensis. We resampled hand long bone lengths in Au. afarensis and extant hominoids, and obtained confidence limits for distributions of manual proportions in the latter. Results confirm that intrinsic manual proportions in Au. afarensis are dissimilar to Pan and Pongo. However, manual proportions in Au. afarensis often fall at the upper end of the distribution in Gorilla, and very lower end in Homo, corresponding to disproportionately short thumbs and long medial digits in Homo. This suggests that manual proportions in Au. afarensis, particularly metacarpal proportions, were not as derived towards Homo as previously described, but rather are intermediate between gorillas and humans. Functionally, these results suggest Au. afarensis could not produce precision grips with the same efficiency as modern humans, which may in part account for the absence of lithic technology in this fossil taxon. Copyright © 2013 Wiley Periodicals, Inc.

  10. Progress in studying scintillator proportionality: Phenomenological model

    SciTech Connect

    Bizarri, Gregory; Cherepy, Nerine; Choong, Woon-Seng; Hull, Giulia; Moses, William; Payne, Sephen; Singh, Jai; Valentine, John; Vasilev, Andrey; Williams, Richard

    2009-04-30

    We present a model to describe the origin of non-proportional dependence of scintillator light yield on the energy of an ionizing particle. The non-proportionality is discussed in terms of energy relaxation channels and their linear and non-linear dependences on the deposited energy. In this approach, the scintillation response is described as a function of the deposited energy deposition and the kinetic rates of each relaxation channel. This mathematical framework allows both a qualitative interpretation and a quantitative fitting representation of scintillation non-proportionality response as function of kinetic rates. This method was successfully applied to thallium doped sodium iodide measured with SLYNCI, a new facility using the Compton coincidence technique. Finally, attention is given to the physical meaning of the dominant relaxation channels, and to the potential causes responsible for the scintillation non-proportionality. We find that thallium doped sodium iodide behaves as if non-proportionality is due to competition between radiative recombinations and non-radiative Auger processes.

  11. A study to evaluate the prevalence of golden proportion and RED proportion in aesthetically pleasing smiles.

    PubMed

    Meshramkar, R; Patankar, A; Lekha, K; Nadiger, R

    2013-03-01

    A beautiful smile is the most striking feature in the face. However beauty is not absolute and is extremely subjective. The aim of this study is to determine the prevalence of 'Golden proportion and Recurring aesthetic dental proportion' in individuals presenting attractive smiles. 214 smile photographs of students of SDM Dental College aged 18-25 years with natural dentition were analysed for their attractiveness based on 6 predetermined criteria. Further, smiles were digitally analysed to evaluate the prevalence of Golden Proportion and Recurring Aesthetic dental proportion (RED) and obtained data was statistically analysed. RED proportion was present in 6.6% of population as opposed to golden proportion which was found in 0.6% of population. It was found that 70% RED was more prevalent than Golden Proportion in attractive as well as unattractive smiles.

  12. Boron-10 Lined Proportional Counter Wall Effects

    SciTech Connect

    Siciliano, Edward R.; Kouzes, Richard T.

    2012-05-01

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based system in the configuration of a coincidence counter. This report provides information about how variations in proportional counter radius and gas pressure in a typical coincident counter design might affect the observed signal from boron-lined tubes. A discussion comparing tubes to parallel plate counters is also included.

  13. Canine Conjectures: Using Data for Proportional Reasoning

    ERIC Educational Resources Information Center

    Westenskow, Arla; Moyer-Packenham, Patricia S.

    2011-01-01

    No person, place, or thing can capture the attention of a class of sixth graders like "man's best friend." To prompt students' interest in a series of lessons on proportional relationships, the authors brought in a unique teaching aid--a dog. A family dog was used to supply the measurements for scatter plots and variables so that students could…

  14. Kitchen Gardens: Contexts for Developing Proportional Reasoning

    ERIC Educational Resources Information Center

    Hilton, Annette; Hilton, Geoff; Dole, Shelley; Goos, Merrilyn; O'Brien, Mia

    2013-01-01

    It is great to see how the sharing of ideas sparks new ideas. In 2011 Lyon and Bragg wrote an "Australian Primary Mathematics Classroom" (APMC) article on the mathematics of kitchen gardens. In this article the authors show how the kitchen garden may be used as a starting point for proportional reasoning. The authors highlight different…

  15. Golden Proportions for the Generalized Tribonacci Numbers

    ERIC Educational Resources Information Center

    Shah, Devbhadra V.; Mehta, Darshana A.

    2009-01-01

    It is known that the ratios of consecutive terms of Fibonacci and Tribonacci sequences converge to the fixed ratio. In this article, we consider the generalized form of Tribonacci numbers and derive the "golden proportion" for the whole family of this generalized sequence. (Contains 2 tables.)

  16. Canine Conjectures: Using Data for Proportional Reasoning

    ERIC Educational Resources Information Center

    Westenskow, Arla; Moyer-Packenham, Patricia S.

    2011-01-01

    No person, place, or thing can capture the attention of a class of sixth graders like "man's best friend." To prompt students' interest in a series of lessons on proportional relationships, the authors brought in a unique teaching aid--a dog. A family dog was used to supply the measurements for scatter plots and variables so that students could…

  17. Tukey-Like Pairwise Comparisons among Proportions.

    ERIC Educational Resources Information Center

    Williams, Richard H.

    1992-01-01

    A QuickBASIC microcomputer program for conducting Tukey-like pairwise comparisons on "k" independent sample proportions is described. The program can accommodate applications involving equal or unequal sample sizes. Studentized range values are computed and displayed on a computer monitor, each of which represents a simple comparison…

  18. Using Artwork to Explore Proportional Reasoning

    ERIC Educational Resources Information Center

    Bush, Sarah B.; Karp, Karen S.; Nadler, Jennifer; Gibbons, Katie

    2016-01-01

    Having an answer to "When are we ever going to use this in real life?" is important to middle school mathematics teachers. The activity described in this article awakened sixth graders' understanding of how artists use mathematics. By exploring ratio and proportionality in different paintings, students realized the use of proportional…

  19. Using Artwork to Explore Proportional Reasoning

    ERIC Educational Resources Information Center

    Bush, Sarah B.; Karp, Karen S.; Nadler, Jennifer; Gibbons, Katie

    2016-01-01

    Having an answer to "When are we ever going to use this in real life?" is important to middle school mathematics teachers. The activity described in this article awakened sixth graders' understanding of how artists use mathematics. By exploring ratio and proportionality in different paintings, students realized the use of proportional…

  20. Golden Proportions for the Generalized Tribonacci Numbers

    ERIC Educational Resources Information Center

    Shah, Devbhadra V.; Mehta, Darshana A.

    2009-01-01

    It is known that the ratios of consecutive terms of Fibonacci and Tribonacci sequences converge to the fixed ratio. In this article, we consider the generalized form of Tribonacci numbers and derive the "golden proportion" for the whole family of this generalized sequence. (Contains 2 tables.)

  1. Research on fluidics, valves, and proportional amplifiers

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Research and development being conducted at the Systems and Controls Laboratory is reviewed. Static characteristics (supply, input, transfer, output, and noise characteristics) of laminar proportional amplifiers were investigated. Other topics discussed include velocity profiles for laminar fluidic jets, speed control systems employing a jet pipe valve, and power amplification with a vortex valve.

  2. Efficacy paradox and proportional contextual effect (PCE).

    PubMed

    Zhang, Weiya; Doherty, Michael

    2017-07-20

    The "efficacy paradox" is when the effect of a treatment tested in an RCT, or evidence-based guideline advice, differs markedly from treatment benefits observed in clinical practice. This arises because in RCT reporting and guideline development treatment efficacy is judged by the separation of the treatment group from the placebo group (the specific treatment effect) whereas in clinical practice it is the overall treatment effect, which includes both specific and contextual responses, that patients experience. This paradox causes a disconnect between guidelines and clinical practice and ignores the importance of contextual response in clinical care. This article fully explains and discusses these issues and presents a possible way to reduce the paradox through an alteration in RCT reporting that shifts the focus to overall treatment benefit and the proportion ("proportional contextual effect") that is explained by placebo and contextual effects. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Proportional reasoning competence among different student populations

    NASA Astrophysics Data System (ADS)

    Wong, King

    2012-10-01

    A collaborative project between Western Washington University, Rutgers University, and New Mexico State University seeks to understand student's competence level on proportional reasoning. We have been collecting and analyzing data from introductory physics and science education courses using a set of assessment tasks. We utilize the notion of constructs to categorize student thinking according to repetitive patterns. Results suggest that, when students confront ratio and proportion problems, they often experience a gap between the mechanics of the mathematical operations and the conscious understanding of what they are doing. In this poster we will share results of our findings from different courses, institutions, and student populations. Supported by NSF grants DUE-1045227, DUE-1045231, DUE-1045250..

  4. Gamma heating measurements with proportional counters

    SciTech Connect

    Chiu, H.; Bennett, E.F.; Micklich, B.J.

    1990-05-01

    A new data acquisition technique (the Continuously-varied Bias- voltage Acquisition mode) has been developed and tested for the low-flux broad-energy regime characteristic of existing fusion blanket mock-ups. This method of analysis allows for the acquisition of data spanning several orders of magnitude in energy with a single proportional counter. Utilizing this method, the gamma energy deposition in a mixed neutron and gamma field was measured. 7 refs., 5 figs.

  5. The evolution of anthropoid molar proportions.

    PubMed

    Carter, Katherine E; Worthington, Steven

    2016-05-20

    Developmental processes that underpin morphological variation have become a focus of interest when attempting to interpret macroevolutionary patterns. Recently, the Dental Inhibitory Cascade (DIC) model has been suggested to explain much of the variation in mammalian molar size proportions. We tested the macroevolutionary implications of this model using anthropoid primate species (n=100), focusing on overall morphological patterns, as well as predictions made about molar size variability, direct developmental control, and diet. Of the species sampled, 56 % had centroids that fell within regions of molar proportion morphospace consistent with the DIC model. We also found that the third molar had greater variation in size than either the first or second molars, as expected by the model. Some DIC model predictions were not supported, however, such as the expected proportion of M 2/M 1 when the third molar is absent. Furthermore, we found that some variability in third molar size could not be explained by the influence of the inhibitory cascade. Overall, we found considerable clade-specific differences in relative molar sizes among anthropoid primates, with hominoids and cercopithecins strongly divergent from DIC model predictions, and platyrrhines, colobines, and papionins more consistent with the inhibitory cascade. Finally, we investigated reasons why some clades deviated from DIC model expectations. Adaptations for frugivory (e.g., bunodont cusp relief) appeared to be one driver of relatively larger second molars and have evolved independently in multiple lineages of anthropoids. The DIC model explains some of the variation in anthropoid primate molar proportions. However, there are interesting deviations away from this broad mammalian pattern, particularly in hominoids and cercopithecins, which suggest the model is only one of multiple mechanisms determining morphological variability in mammalian teeth.

  6. Developing Essential Understanding of Ratios, Proportions, and Proportional Reasoning for Teaching Mathematics: Grades 6-8

    ERIC Educational Resources Information Center

    Lobato, Joanne; Ellis, Amy; Zbiek, Rose Mary

    2010-01-01

    How do you refute the erroneous claim that all ratios are fractions? This book goes beyond a simple introduction to ratios, proportions, and proportional reasoning. It will help broaden and deepen your mathematical understanding of one of the most challenging topics for students--and teachers--to grasp. It will help you engage your students,…

  7. NASA CONNECT: Proportionality: Modeling the Future

    NASA Technical Reports Server (NTRS)

    2000-01-01

    'Proportionality: Modeling the Future' is the sixth of seven programs in the 1999-2000 NASA CONNECT series. Produced by NASA Langley Research Center's Office of Education, NASA CONNECT is an award-winning series of instructional programs designed to enhance the teaching of math, science and technology concepts in grades 5-8. NASA CONNECT establishes the 'connection' between the mathematics, science, and technology concepts taught in the classroom and NASA research. Each program in the series supports the national mathematics, science, and technology standards; includes a resource-rich teacher guide; and uses a classroom experiment and web-based activity to complement and enhance the math, science, and technology concepts presented in the program. NASA CONNECT is FREE and the programs in the series are in the public domain. Visit our web site and register. http://connect.larc.nasa.gov 'Proportionality: Modeling the Future', students will examine how patterns, measurement, ratios, and proportions are used in the research, development, and production of airplanes.

  8. Evaluation of Facial Beauty Using Anthropometric Proportions

    PubMed Central

    Milutinovic, Jovana

    2014-01-01

    The improvement of a patient's facial appearance is one of the main goals of contemporary orthodontic treatment. The aim of this investigation was to evaluate the difference in facial proportions between attractive and anonymous females in order to establish objective facial features which are widely considered as beautiful. The study included two groups: first group consisted of 83 Caucasian female subjects between 22 and 28 years of age who were selected from the population of students at the University of Belgrade, and the second group included 24 attractive celebrity Caucasian females. The en face facial photographs were taken in natural head position (NHP). Numerous parameters were recorded on these photographs, in order to establish facial symmetry and correlation with the ideal set of proportions. This study showed significant difference between anonymous and attractive females. Attractive females showed smaller face in general and uniformity of the facial thirds and fifths, and most of the facial parameters meet the criteria of the ideal proportions. PMID:24701166

  9. Learning With Label Proportions via NPSVM.

    PubMed

    Qi, Zhiquan; Wang, Bo; Meng, Fan; Niu, Lingfeng

    2017-10-01

    Recently, learning from label proportions (LLPs), which seeks generalized instance-level predictors merely based on bag-level label proportions, has attracted widespread interest. However, due to its weak label scenario, LLP usually falls into a transductive learning framework accounting for an intractable combinatorial optimization issue. In this paper, we propose a brand new algorithm, called LLPs via nonparallel support vector machine (LLP-NPSVM), to facilitate this dilemma. To harness satisfactory data adaption, instead of transductive learning fashion, our scheme determined instance labels according to two nonparallel hyper-planes under the supervision of label proportion information. In a geometrical view, our approach can be interpreted as an alternative competitive method benefiting from large margin clustering. In practice, LLP-NPSVM can be efficiently addressed by applying two fast sequential minimal optimization paths iteratively. To rationally support the effectiveness of our method, finite termination and monotonic decrease of the proposed LLP-NPSVM procedure were essentially analyzed. Various experiments demonstrated our algorithm enjoys rapid convergence and robust numerical stability, along with best accuracies among several recently developed methods in most cases.

  10. Student Obstacles in Ratio and Proportion Learning

    NASA Astrophysics Data System (ADS)

    Andini, W.; Jupri, Al

    2017-02-01

    Ratio and proportion are mathematics topics that are learned in elementary school. In the learning process, teachers often found students who have difficulties in learning these topics. Analysing the difficulties on the topics is important for teachers, as an attempt to doa reflection of the learning process and as a reference in devising a learning plan, including for anticipation of the possibility of these barriers that might appear in the next learning process. This research used as the qualitative method, and involved 49 students of grade 5 and one teacher. From the analysis of the data, i.e., student test results and observation of the learning, we found some obstacles that faced by students, such as students confused in understanding about ratio and proportion topic, students found it difficult in completing the problem which have different contexts, the learning material of ratio and proportion topic that presented in textbooks are still partial (not depth), and the lack of ability of the teacher in creating problems.

  11. Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient

    PubMed Central

    Yamane, Yuta; Hemmatiyan, Shayan; Ieda, Jun'ichi; Maekawa, Sadamichi; Sinova, Jairo

    2014-01-01

    Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter β that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient. PMID:25365971

  12. Proportional wire calorimeter for magnet pole tips

    SciTech Connect

    Kraus, D; Ludlam, T; Renardy, J; Willis, W; Zurfluh, E

    1980-01-01

    A total absorption calorimeter is designed to have magnetic properties comparable to those of ordinary steel, and thus can be incorporated into the poles of a spectrometer magnet without compromising the field quality. A test device has been built which consists of an iron structure penetrated by a finegrain pattern of holes, each acting as a proportional tube such that 90% of the volume is occupied by iron. Measurements of the energy and space resolution of this device in a high energy beam will be presented.

  13. Neutron spectrometry with He-3 proportional counters

    SciTech Connect

    Manolopoulou, M.; Fragopoulou, M.; Stoulos, S.; Vagena, E.; Westmeier, W.; Zamani, M.

    2011-07-01

    Helium filled proportional counters are widely used in the field of neutron detection and spectrometry. In this work the response of a commercially available He-3 counter is studied experimentally and calculated with Monte Carlo for the neutron energy range from 230 keV up to about 7 MeV. The calculated response of the system is used to determine neutron yield energy distribution emitted from an extended {sup nat}U/Pb assembly irradiated with 1.6 GeV deuterons. The results are in acceptable agreement with the calculated neutron distribution with DCM-DEM code. (authors)

  14. Sensing circuits for multiwire proportional chambers

    NASA Technical Reports Server (NTRS)

    Peterson, H. T.; Worley, E. R.

    1977-01-01

    Integrated sensing circuits were designed, fabricated, and packaged for use in determining the direction and fluence of ionizing radiation passing through a multiwire proportional chamber. CMOS on sapphire was selected because of its high speed and low power capabilities. The design of the proposed circuits is described and the results of computer simulations are presented. The fabrication processes for the CMOS on sapphire sensing circuits and hybrid substrates are outlined. Several design options are described and the cost implications of each discussed. To be most effective, each chip should handle not more than 32 inputs, and should be mounted on its own hybrid substrate.

  15. Kalman-predictive-proportional-integral-derivative (KPPID)

    SciTech Connect

    Fluerasu, A.; Sutton, M.

    2004-12-17

    With third generation synchrotron X-ray sources, it is possible to acquire detailed structural information about the system under study with time resolution orders of magnitude faster than was possible a few years ago. These advances have generated many new challenges for changing and controlling the state of the system on very short time scales, in a uniform and controlled manner. For our particular X-ray experiments on crystallization or order-disorder phase transitions in metallic alloys, we need to change the sample temperature by hundreds of degrees as fast as possible while avoiding over or under shooting. To achieve this, we designed and implemented a computer-controlled temperature tracking system which combines standard Proportional-Integral-Derivative (PID) feedback, thermal modeling and finite difference thermal calculations (feedforward), and Kalman filtering of the temperature readings in order to reduce the noise. The resulting Kalman-Predictive-Proportional-Integral-Derivative (KPPID) algorithm allows us to obtain accurate control, to minimize the response time and to avoid over/under shooting, even in systems with inherently noisy temperature readings and time delays. The KPPID temperature controller was successfully implemented at the Advanced Photon Source at Argonne National Laboratories and was used to perform coherent and time-resolved X-ray diffraction experiments.

  16. Energy Proportionality for Disk Storage Using Replication

    SciTech Connect

    Kim, Jinoh; Rotem, Doron

    2010-09-09

    Energy saving has become a crucial concern in datacenters as several reports predict that the anticipated energy costs over a three year period will exceed hardware acquisition. In particular, saving energy for storage is of major importance as storage devices (and cooling them off) may contribute over 25 percent of the total energy consumed in a datacenter. Recent work introduced the concept of energy proportionality and argued that it is a more relevant metric than just energy saving as it takes into account the tradeoff between energy consumption and performance. In this paper, we present a novel approach, called FREP (Fractional Replication for Energy Proportionality), for energy management in large datacenters. FREP includes areplication strategy and basic functions to enable flexible energy management. Specifically, our method provides performance guarantees by adaptively controlling the power states of a group of disks based on observed and predicted workloads. Our experiments, using a set of real and synthetic traces, show that FREP dramatically reduces energy requirements with a minimal response time penalty.

  17. Proportionality and quantitative relationships in physics

    NASA Astrophysics Data System (ADS)

    Gamble, R.

    1986-11-01

    Considers some aspects of quantitative relationships involved in learning physics. These are proportionality, various kinds of equality and the need for generality. The distinctions may seem to some extent artificial, for the physics curriculum is very much a seamless robe. However, some distinguishing is necessary if the physics curriculum is to be examined with regard to pupil outcomes. Knowledge relevant to proportionality and other aspects of quantitative relationships (which is often perhaps implicitly assumed) should be subsumed by the successful learning of physics: as such it need not feature in summative assessment and does not seem to do so in practice. If, however, some children fail to learn much physics theory, for whatever reason, they could be far more aware of the difficulties involved that are either their teachers or their more successful colleagues. It could be the case that some children become confused or demotivated by some of the various aspects of quantitative relationships and so remain confused or ignorant as regard the intended outcomes of the curriculum. The literature indicates that many children do indeed remain confused and/or ignorant (e.g. see Gilbert and Watts 1983).

  18. Viking-Age Sails: Form and Proportion

    NASA Astrophysics Data System (ADS)

    Bischoff, Vibeke

    2017-01-01

    Archaeological ship-finds have shed much light on the design and construction of vessels from the Viking Age. However, the exact proportions of their sails remain unknown due to the lack of fully preserved sails, or other definite indicators of their proportions. Key Viking-Age ship-finds from Scandinavia—the Oseberg Ship, the Gokstad Ship and Skuldelev 3—have all revealed traces of rigging. In all three finds, the keelson—with the mast position—is preserved, together with fastenings for the sheets and the tack, indicating the breadth of the sail. The sail area can then be estimated based on practical experience of how large a sail the specific ship can carry, in conjunction with hull form and displacement. This article presents reconstructions of the form and dimensions of rigging and sail based on the archaeological finds, evidence from iconographic and written sources, and ethnographic parallels with traditional Nordic boats. When these sources are analysed, not only do the similarities become apparent, but so too does the relative disparity between the archaeological record and the other sources. Preferential selection in terms of which source is given the greatest merit is therefore required, as it is not possible to afford them all equal value.

  19. Viking-Age Sails: Form and Proportion

    NASA Astrophysics Data System (ADS)

    Bischoff, Vibeke

    2017-04-01

    Archaeological ship-finds have shed much light on the design and construction of vessels from the Viking Age. However, the exact proportions of their sails remain unknown due to the lack of fully preserved sails, or other definite indicators of their proportions. Key Viking-Age ship-finds from Scandinavia—the Oseberg Ship, the Gokstad Ship and Skuldelev 3—have all revealed traces of rigging. In all three finds, the keelson—with the mast position—is preserved, together with fastenings for the sheets and the tack, indicating the breadth of the sail. The sail area can then be estimated based on practical experience of how large a sail the specific ship can carry, in conjunction with hull form and displacement. This article presents reconstructions of the form and dimensions of rigging and sail based on the archaeological finds, evidence from iconographic and written sources, and ethnographic parallels with traditional Nordic boats. When these sources are analysed, not only do the similarities become apparent, but so too does the relative disparity between the archaeological record and the other sources. Preferential selection in terms of which source is given the greatest merit is therefore required, as it is not possible to afford them all equal value.

  20. ProPortal: A Database for Prochlorococcus

    DOE Data Explorer

    Huang, Katherine [Chisholm lab, MIT

    Prochlorococcus is a marine cyanobacterium that numerically dominates the mid-latitude oceans, and is the smallest known oxygenic phototroph. All isolates described thus far can be assigned to either a tightly clustered high-light (HL) adapted clade, or a more divergent low-light (LL) adapted group. They are closely related to, but distinct from, marine Synechococcus. The genomes of 12 strains have been sequenced and they range in size from 1.6 to 2.6 Mbp. They represent diverse lineages, spanning the rRNA diversity (97 to 99.93% similarity) of cultured representatives of this group. Our analyses of these genomes inform our understanding of how adaptation occurs in the oceans along gradients of light, nutrients, and other environmental factors, providing essential context for interpreting rapidly expanding metagenomic datasets. [Copied from http://proportal.mit.edu/project/prochlorococcus/] ProPortal allows users to browse and search genome date for not only Prochlorococcus, but Cyanophage and Synechococcus. Microarray data, environmental cell concentration data, and metagenome information are also available.

  1. Human patellar articular proportions: recent and Pleistocene patterns

    PubMed Central

    TRINKAUS, ERIK

    2000-01-01

    The degrees of mediolateral asymmetry of the patellar articular facet, as well as the median and lateral articular angles of the facet, were compared across samples of recent humans and of Pleistocene archaic and modern fossil humans. All samples exhibit considerable variability in these patellar proportions. The articular angles are similar across the different samples, but there is a trend towards decreasing lateral angles with decreasing robusticity. The archaic humans exhibit significantly more symmetry of the medial and lateral facets than do any of the recent human samples. However, given the variability in medial versus lateral patellofemoral contact forces documented for extant humans and the roles of the distal oblique portions of vastus medialis and vastus lateralis in patellar stabilisation, it is unclear to what extent this variation in patellar articular proportions may affect knee kinesiology. The contrasts may be related to different levels of patellar stability and/or musculoskeletal hypertrophy, but they appear unlikely to have affected primary knee function. PMID:10853969

  2. TRIAC/SCR proportional control circuit

    DOEpatents

    Hughes, Wallace J.

    1999-01-01

    A power controller device which uses a voltage-to-frequency converter in conjunction with a zero crossing detector to linearly and proportionally control AC power being supplied to a load. The output of the voltage-to frequency converter controls the "reset" input of a R-S flip flop, while an "0" crossing detector controls the "set" input. The output of the flip flop triggers a monostable multivibrator controlling the SCR or TRIAC firing circuit connected to the load. Logic gates prevent the direct triggering of the multivibrator in the rare instance where the "reset" and "set" inputs of the flip flop are in coincidence. The control circuit can be supplemented with a control loop, providing compensation for line voltage variations.

  3. TRIAC/SCR proportional control circuit

    DOEpatents

    Hughes, W.J.

    1999-04-06

    A power controller device is disclosed which uses a voltage-to-frequency converter in conjunction with a zero crossing detector to linearly and proportionally control AC power being supplied to a load. The output of the voltage-to frequency converter controls the ``reset`` input of a R-S flip flop, while an ``0`` crossing detector controls the ``set`` input. The output of the flip flop triggers a monostable multivibrator controlling the SCR or TRIAC firing circuit connected to the load. Logic gates prevent the direct triggering of the multivibrator in the rare instance where the ``reset`` and ``set`` inputs of the flip flop are in coincidence. The control circuit can be supplemented with a control loop, providing compensation for line voltage variations. 9 figs.

  4. Conductance and Kondo Interference beyond Proportional Coupling

    NASA Astrophysics Data System (ADS)

    Dias da Silva, Luis G. G. V.; Lewenkopf, Caio H.; Vernek, Edson; Ferreira, Gerson J.; Ulloa, Sergio E.

    2017-09-01

    The transport properties of nanostructured systems are deeply affected by the geometry of the effective connections to metallic leads. In this work we derive a conductance expression for a class of interacting systems whose connectivity geometries do not meet the Meir-Wingreen proportional coupling condition. As an interesting application, we consider a quantum dot connected coherently to tunable electronic cavity modes. The structure is shown to exhibit a well-defined Kondo effect over a wide range of coupling strengths between the two subsystems. In agreement with recent experimental results, the calculated conductance curves exhibit strong modulations and asymmetric behavior as different cavity modes are swept through the Fermi level. These conductance modulations occur, however, while maintaining robust Kondo singlet correlations of the dot with the electronic reservoir, a direct consequence of the lopsided nature of the device.

  5. A proportional temperature controller with automatic shutoff

    NASA Astrophysics Data System (ADS)

    Lucich, G. M.; Holland, P. W.

    1980-08-01

    A sensitive, proportional temperature controller useful in the temperature range from 40 to 400 C with an accuracy of plus or minus 0.1 C is described. It is potentially useful for regulating temperatures in air chambers, liquid baths, furnaces and reaction vessels and for other applications. This instrument was developed to control the duration and temperature of the heating cycle of a charcoal filled adsorber that is part of a special helium analyzer. The controller was made from commercially available parts and can be easily modified to provide continuous temperature control. The circuit is solid state and employs no electromechanical devices. Over a 2 year period of use as a component of the special helium analyzer, this temperature controller performed successfully and required no maintenance.

  6. Microstrip proportional counter development at MSFC

    NASA Technical Reports Server (NTRS)

    Fulton, M. A.; Kolodziejczak, J. J.; Ramsey, B. D.

    1992-01-01

    Microstrip detectors are an exciting new development in proportional counter design fabricated using integrated circuit-type photolithography techniques; they therefore offer very high spatial accuracy and uniformity. A development program is underway at NASA-Marshall to produce large-area microstrips for use in an X-ray detector balloon flight program and to investigate the general performance limits of these new devices. Microstrips tested so far have been fabricated both in-house using standard photolithographic techniques and by an outside contractor using electron beam technology. Various substrate materials have been tested along with different electrode configurations. The distributions of pickup on subdivided cathodes on both top and bottom surfaces of the microstrips are also being investigated for use as two-dimensional imaging detectors. Data from these tests in the development of a large-area device will be presented.

  7. Scaling and universality in proportional elections.

    PubMed

    Fortunato, Santo; Castellano, Claudio

    2007-09-28

    A most debated topic of the last years is whether simple statistical physics models can explain collective features of social dynamics. A necessary step in this line of endeavor is to find regularities in data referring to large-scale social phenomena, such as scaling and universality. We show that, in proportional elections, the distribution of the number of votes received by candidates is a universal scaling function, identical in different countries and years. This finding reveals the existence in the voting process of a general microscopic dynamics that does not depend on the historical, political, and/or economical context where voters operate. A simple dynamical model for the behavior of voters, similar to a branching process, reproduces the universal distribution.

  8. Boron-10 Lined Proportional Counter Model Validation

    SciTech Connect

    Lintereur, Azaree T.; Siciliano, Edward R.; Kouzes, Richard T.

    2012-06-30

    The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project “Coincidence Counting With Boron-Based Alternative Neutron Detection Technology” at Pacific Northwest National Laboratory (PNNL) for the development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube-based alternative system in the configuration of a coincidence counter. This report discusses the validation studies performed to establish the degree of accuracy of the computer modeling methods current used to simulate the response of boron-lined tubes. This is the precursor to developing models for the uranium neutron coincidence collar under Task 2 of this project.

  9. Proportionality between chest wall resistance and elastance.

    PubMed

    Barnas, G M; Stamenović, D; Fredberg, J J

    1991-02-01

    Fredberg and Stamenovic (J. Appl. Physiol. 67: 2408-2419, 1989) demonstrated a relatively robust phenomenological relationship between resistance (R) and elastance (E) of lung tissue during external forcing. The relationship can be expressed as omega R = eta E, where omega = 2 pi times forcing frequency and eta is hysteresivity; they found eta to be remarkably invariant under a wide range of circumstances. From data gathered in previous experiments, we have tested the adequacy and utility of this phenomenological description for the chest wall (eta w) and its major compartments, the rib cage (eta rc), diaphragm-abdomen (eta d-a), and belly wall (eta bw+). For forcing frequencies and tidal volumes within the normal range of breathing, we found that eta w remained in a relatively narrow range (0.27-0.37) and that neither eta w nor the compartmental eta's changed much with frequency or tidal volume. Compared with eta w, eta rc tended to be slightly low, whereas eta d-a tended to be slightly higher than eta w. However, at higher frequencies (greater than 1 Hz) all eta's increased appreciably with frequency. During various static nonrespiratory maneuvers involving use of respiratory muscles, eta w increased up to twofold. We conclude that in the normal ranges of breathing frequency and tidal volume 1) elastic and dissipative processes within the chest wall appear to be coupled, 2) eta's of the various component parts of the chest wall are well matched, 3) respiratory muscle contraction increases the ratio of cyclic dissipative losses to energy storage, and 4) R of the relaxed chest wall can be estimated from E.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Smooth bootstrap-based confidence intervals for one binomial proportion and difference of two proportions.

    PubMed

    Wang, Dongliang; Hutson, Alan D

    Constructing confidence intervals (CIs) for a binomial proportion and the difference between two binomial proportions is a fundamental and well-studied problem with respect to the analysis of binary data. In this note, we propose a new bootstrap procedure to estimate the CIs by resampling from a newly developed smooth quantile function in [11] for discrete data. We perform a variety of simulation studies in order to illustrate the strong performance of our approach. The coverage probabilities of our CIs in the one-sample setting are superior than or comparable to other well-known approaches. The true utility of our new and novel approach is in the two-sample setting. For the difference of two proportions, our smooth bootstrap CIs provide better coverage probabilities almost uniformly over the interval (-1, 1), particularly in the tail region as compared than other published methods included in our simulation. We illustrate our methodology via an application to several different binary data sets.

  11. Proportional mortality of 50 years and above

    PubMed Central

    Swaroop, S.; Uemura, K.

    1957-01-01

    In 1954 the United Nations Committee of Experts on International Definition and Measurement of Standards and Levels of Living suggested that for the measurement of levels of living quantifiable or potentially quantifiable components should be considered separately. An attempt is made in the present paper to evolve a single, comprehensive numerical indicator to quantify the component “health, including demographic conditions”. The use of an objective statistical technique as a guide in the selection of such an indicator is suggested. From the application of this technique, it is concluded that the percentage of deaths at the ages 50 years and over to total deaths (proportional mortality) affords a fairly suitable yardstick by which broad inter-country comparisons may be made. This indicator has the advantages of simplicity of calculation, comprehensiveness, availability of data, possibility of international comparability despite the varying quality of basic statistical information, sensitivity for the purpose of inter-country comparisons, and validity for studying levels and trends. PMID:13500159

  12. Environmental drivers of sapwood and heartwood proportions

    NASA Astrophysics Data System (ADS)

    Thurner, Martin; Beer, Christian

    2017-04-01

    Recent advances combining information on stem volume from remote sensing with allometric relationships derived from forest inventory databases have led to spatially continuous estimates of stem, branch, root and foliage biomass in northern boreal and temperate forests. However, a separation of stem biomass into sapwood and heartwood mass has remained unsolved, despite their important differences in biogeochemical function, for instance concerning their contribution to tree respiratory costs. Although relationships between sapwood cross-sectional area and supported leaf area are well established, less is known about relations between sapwood or heartwood mass and other traits (e.g. stem mass), since these biomass compartments are more difficult to measure in practice. Here we investigate the variability in sapwood and heartwood proportions and determining environmental factors. For this task we explore an available biomass and allometry database (BAAD) and study relative sapwood and heartwood area, volume, mass and density in dependence of tree species, age and climate. First, a theoretical framework on how to estimate sap- and heartwood mass from stem mass is developed. Subsequently, the underlying assumptions and relationships are explored with the help of the BAAD. The established relationships can be used to derive spatially continuous sapwood and heartwood mass estimates by applying them to remote sensing based stem volume products. This would be a fundamental step forward to a data-driven estimate of autotrophic respiration.

  13. Exact tests for Hardy-Weinberg proportions.

    PubMed

    Engels, William R

    2009-12-01

    Exact conditional tests are often required to evaluate statistically whether a sample of diploids comes from a population with Hardy-Weinberg proportions or to confirm the accuracy of genotype assignments. This requirement is especially common when the sample includes multiple alleles and sparse data, thus rendering asymptotic methods, such as the common chi(2)-test, unreliable. Such an exact test can be performed using the likelihood ratio as its test statistic rather than the more commonly used probability test. Conceptual advantages in using the likelihood ratio are discussed. A substantially improved algorithm is described to permit the performance of a full-enumeration exact test on sample sizes that are too large for previous methods. An improved Monte Carlo algorithm is also proposed for samples that preclude full enumeration. These algorithms are about two orders of magnitude faster than those currently in use. Finally, methods are derived to compute the number of possible samples with a given set of allele counts, a useful quantity for evaluating the feasibility of the full enumeration procedure. Software implementing these methods, ExactoHW, is provided.

  14. Medium-Assisted Vacuum Force

    NASA Astrophysics Data System (ADS)

    Tomaš, M. S.

    We discuss some implications of a very recently obtained result for the force on a slab in a planar cavity based on the calculation of the vacuum Lorentz force [C.Raabe and D.-G. Welsch, Phys. Rev. A 71 (2005) 013814]. We demonstrate that, according to this formula, the total force on the slab consists of a medium-screened Casimir force and, in addition to it, a medium-assisted force. The sign of of the medium-assisted force is determined solely by the properties of the cavity mirrors. In the Lifshitz configuration, this force is proportional to 1/d at small distances and is very small compared with the corresponding van der Waals force. At large distances, however, it is proportional to 1/d4 and comparable with the Casimir force, especially for denser media. The exponents in these power laws decrease by 1 in the case of a thin slab. The formula for the medium-assisted force also describes the force on a layer of the cavity medium, which has similar properties. For dilute media, it implies an atom-mirror interaction of the Coulomb type at small and of the Casimir-Polder type at large atom-mirror distances. For a perfectly reflecting mirror, the latter force is effectively only three-times smaller than the Casimir-Polder force.

  15. Large-scale magnetic field generation by randomly forced shearing waves.

    PubMed

    Heinemann, T; McWilliams, J C; Schekochihin, A A

    2011-12-16

    A rigorous theory for the generation of a large-scale magnetic field by random nonhelically forced motions of a conducting fluid combined with a linear shear is presented in the analytically tractable limit of low magnetic Reynolds number (Rm) and weak shear. The dynamo is kinematic and due to fluctuations in the net (volume-averaged) electromotive force. This is a minimal proof-of-concept quasilinear calculation aiming to put the shear dynamo, a new effect recently found in numerical experiments, on a firm theoretical footing. Numerically observed scalings of the wave number and growth rate of the fastest-growing mode, previously not understood, are derived analytically. The simplicity of the model suggests that shear dynamo action may be a generic property of sheared magnetohydrodynamic turbulence.

  16. GSFC's Multi-Wire Gas Proportional Counter

    NASA Astrophysics Data System (ADS)

    Serlemitsos, Peter J.

    2013-01-01

    The Goddard X-ray group made its appearance in 1964 as a one person (Elihu Boldt) appendage to the well established cosmic ray group, then headed by Frank MacDonald. This discipline proximity was crucial because it meant superb technical support from the start, which allowed the fledging group to quickly advance toward directions of choice. When I became the 2nd member of the group in 1966, the new discipline still relied on bulky gas counters, stacked to make up a usable detection area. Slim opportunities existed for timing or spectral inferences. Elihu's strong interest in pursuing the reported diffuse cosmic radiation had to be set aside, as improving this situation appeared to be years away. Cosmic ray researchers had long used charged particle timing techniques for cleaning up their data, but those appeared irrelevant for our purposes because of the large, background generating, mass of the gas containment vessels and the slow drift in the counter gas of the charge from photon interaction sites to the counter anode. We had to deal with these realities in whatever choices we made for our future instruments. The multi-wire gas proportional counter emerged from our still small group in the late1960s, demonstrating on several rocket and balloon flights a greatly reduced detector background, improved event timing and adequate resolution for addressing key spectral features. Three of these detectors, flown in 1975 on NASA's 8th orbiting solar observatory, were successfully used for some 3 years to conduct non dispersive, 1-10 keV spectroscopy on many galactic and extragalactic sources, including several clusters of galaxies. In 1977 we flew a set of larger detectors on the first of NASA's High Energy Astrophysical Observatories (HEAO). These were specifically designed for the study of the X-ray background. Finally, the largest instruments of this family were flown in 1995 by our group on NASA's Rossi X-ray Timing Explorer, RXTE, which observed over a remarkable 16

  17. Determination of activity coefficient of lanthanum chloride in molten LiCl-KCl eutectic salt as a function of cesium chloride and lanthanum chloride concentrations using electromotive force measurements

    NASA Astrophysics Data System (ADS)

    Bagri, Prashant; Simpson, Michael F.

    2016-12-01

    The thermodynamic behavior of lanthanides in molten salt systems is of significant scientific interest for the spent fuel reprocessing of Generation IV reactors. In this study, the apparent standard reduction potential (apparent potential) and activity coefficient of LaCl3 were determined in a molten salt solution of eutectic LiCl-KCl as a function of concentration of LaCl3. The effect of adding up to 1.40 mol % CsCl was also investigated. These properties were determined by measuring the open circuit potential of the La-La(III) redox couple in a high temperature molten salt electrochemical cell. Both the apparent potential and activity coefficient exhibited a strong dependence on concentration. A low concentration (0.69 mol %) of CsCl had no significant effect on the measured properties, while a higher concentration (1.40 mol %) of CsCl caused an increase (become more positive) in the apparent potential and activity coefficient at the higher range of LaCl3 concentrations.

  18. Force Limited Vibration Testing

    NASA Technical Reports Server (NTRS)

    Scharton, Terry; Chang, Kurng Y.

    2005-01-01

    This slide presentation reviews the concept and applications of Force Limited Vibration Testing. The goal of vibration testing of aerospace hardware is to identify problems that would result in flight failures. The commonly used aerospace vibration tests uses artificially high shaker forces and responses at the resonance frequencies of the test item. It has become common to limit the acceleration responses in the test to those predicted for the flight. This requires an analysis of the acceleration response, and requires placing accelerometers on the test item. With the advent of piezoelectric gages it has become possible to improve vibration testing. The basic equations have are reviewed. Force limits are analogous and complementary to the acceleration specifications used in conventional vibration testing. Just as the acceleration specification is the frequency spectrum envelope of the in-flight acceleration at the interface between the test item and flight mounting structure, the force limit is the envelope of the in-flight force at the interface . In force limited vibration tests, both the acceleration and force specifications are needed, and the force specification is generally based on and proportional to the acceleration specification. Therefore, force limiting does not compensate for errors in the development of the acceleration specification, e.g., too much conservatism or the lack thereof. These errors will carry over into the force specification. Since in-flight vibratory force data are scarce, force limits are often derived from coupled system analyses and impedance information obtained from measurements or finite element models (FEM). Fortunately, data on the interface forces between systems and components are now available from system acoustic and vibration tests of development test models and from a few flight experiments. Semi-empirical methods of predicting force limits are currently being developed on the basis of the limited flight and system test

  19. A study of dentists' preferred maxillary anterior tooth width proportions: comparing the recurring esthetic dental proportion to other mathematical and naturally occurring proportions.

    PubMed

    Ward, Daniel H

    2007-01-01

    Presently, there are no generally accepted standards for designing smiles using tooth proportion relationships. The purpose of this study was to determine whether North American dentists prefer smile designs created using the recurring esthetic dental (RED) proportion, other mathematically defined tooth proportion relationships, or naturally occurring tooth-to-tooth width proportions previously reported to occur in the North American population. Three hundred and one North American dentists were surveyed to determine their preferences of imaged smiles exhibiting different anterior tooth width proportions and the primary proportion influencing their decision. One-sample t-tests were used to compare preferences of constructed smiles. Pearson's Chi-square test was used to assess the independence of the relationship between the subjects' demographic attributes and the factors reported as being instrumental in their decision processes. Fifty-seven percent of dentists surveyed preferred the smiles with the 70% RED proportion over the smiles with the naturally occurring maxillary anterior tooth width proportions in normal-length teeth. Dentists preferred the smiles of the naturally occurring maxillary tooth proportions (70%) and the 70% RED proportion (75%) over the golden proportion. In smiles with tall teeth, the golden proportion was preferred by 58% of the surveyed dentists over the naturally occurring tooth-to-tooth width proportions as previously defined by Preston. Sixty-two percent of dentists cited the overall balance as the primary factor affecting their selection. Twenty-three percent made their selection based on the size of the maxillary central incisors, whereas 15% used other teeth or factors. Smiles created using the principles of the RED proportion were preferred by a majority of dentists surveyed. The majority of dentists reported that overall balance was the primary factor affecting their selection. The RED proportion may be useful in creating smiles

  20. A stochastic approximation algorithm for estimating mixture proportions

    NASA Technical Reports Server (NTRS)

    Sparra, J.

    1976-01-01

    A stochastic approximation algorithm for estimating the proportions in a mixture of normal densities is presented. The algorithm is shown to converge to the true proportions in the case of a mixture of two normal densities.

  1. Mathematically modelling proportions of Japanese populations by industry

    NASA Astrophysics Data System (ADS)

    Hirata, Yoshito

    2016-10-01

    I propose a mathematical model for temporal changes of proportions for industrial sectors. I prove that the model keeps the proportions for the primary, the secondary, and the tertiary sectors between 0 and 100% and preserves their total as 100%. The model fits the Japanese historical data between 1950 and 2005 for the population proportions by industry very well. The model also predicts that the proportion for the secondary industry becomes negligible and becomes less than 1% at least around 2080.

  2. Spatial Proportional Reasoning Is Associated with Formal Knowledge about Fractions

    ERIC Educational Resources Information Center

    Möhring, Wenke; Newcombe, Nora S.; Levine, Susan C.; Frick, Andrea

    2016-01-01

    Proportional reasoning involves thinking about parts and wholes (i.e., about fractional quantities). Yet, research on proportional reasoning and fraction learning has proceeded separately. This study assessed proportional reasoning and formal fraction knowledge in 8- to 10-year-olds. Participants (N = 52) saw combinations of cherry juice and water…

  3. Proportion in Middle-School Mathematics: It's Everywhere

    ERIC Educational Resources Information Center

    Shield, Mal; Dole, Shelley

    2008-01-01

    Proportional thinking is the mathematical basis of a wide range of topics in the middle-school mathematics curriculum. While the concept is obvious in the traditionally-named ratio and proportion sections, proportional thinking is also the key to such diverse topics as rate, gradient of a linear function, similarity, trigonometry and percentage,…

  4. Pre-Service Teachers' Responses for Ratio and Proportion Items

    ERIC Educational Resources Information Center

    Livy, Sharyn; Herbert, Sandra

    2013-01-01

    Proportional reasoning is important for informed decisions in proportional problem situations. This paper reports on mathematical content knowledge related to proportional reasoning of second-year, pre-service teachers. Responses to two ratio items provide insights into their correct method of solutions and common misconceptions. Anchor Points…

  5. Evaluation of facial divine proportion in North Indian Population

    PubMed Central

    Khan, Naseem Ahmad; Nagar, Amit; Tandon, Pradeep; Singh, Gulshan Kumar; Singh, Alka

    2016-01-01

    Objective: To evaluate the facial divine proportion and its relationship with facial attractiveness in North Indian population. Materials and Methods: For evaluation of various facial proportions, standardized frontal facial photographs of total 300 subjects between 18 and 30 years of age were obtained. Black and white copies of these photographs were presented in front of an evaluation jury for assigning scores of facial attractiveness and finally 130 attractive subjects were selected. These subjects were divided into two groups, Group I (attractive females n = 65) and Group II (attractive males n = 65) and they were further analyzed for various parameters of facial proportions. Unpaired Student's t-test was used to compare both groups. Results: Group I showed that five of seven vertical facial proportions were close to divine proportion (1.618) whereas only two vertical proportions in Group II were close to it. Transverse facial proportions in both groups deviated more from divine proportion (1.618) and were closer to silver proportion (1.414). Conclusions: Most of the facial proportions of attractive females in the North-Indian population were close to the divine proportion. Thus, facial divine proportion could be an important factor in the perception of facial attractiveness of North-Indian attractive females. PMID:27630502

  6. Spatial Proportional Reasoning Is Associated with Formal Knowledge about Fractions

    ERIC Educational Resources Information Center

    Möhring, Wenke; Newcombe, Nora S.; Levine, Susan C.; Frick, Andrea

    2016-01-01

    Proportional reasoning involves thinking about parts and wholes (i.e., about fractional quantities). Yet, research on proportional reasoning and fraction learning has proceeded separately. This study assessed proportional reasoning and formal fraction knowledge in 8- to 10-year-olds. Participants (N = 52) saw combinations of cherry juice and water…

  7. Theoretical Investigation of a Proportional-Plus-Flicker Automatic Pilot

    NASA Technical Reports Server (NTRS)

    Seaberg, Ernest C.

    1950-01-01

    The proportional-plus-flicker automatic pilot operates by a nonlinear principle whereby a fast-acting flicker servomotor response is combined with a low-speed proportional servomotor response for the purpose of obtaining supersonic stability and control. Essentially, the autopilot maintains a zero reference about which the output is proportional to the input. However, a flicker response overrides this proportional response at a fixed angle of gimbal displacement on either side of the zero gyroscope reference. Therefore, in contrast to other high speed control systems, the design requirements are simplified because the two components of the proportional-flicker control system are easy to build separately and they can be combined in a relatively simple manner. By application of the proportional-flicker principle, satisfactory stability can be obtained by the proper adjustment of the variable factors in the autopilot mechanism; namely, the proportional gain, the amplitude of flicker control deflection, the autopilot time-lag factor (the time-lag between flicker and proportional operation), and the point in the range that the autopilot switches from a flicker to a proportional system. There is a possibility that these factors can be adjusted so that a more rapid response time (the time to reach steady state) is obtained with the non-linear proportional-flicker autopilot than with a purely linear proportional autopilot. For the main part of this analysis, the proportional part of the system is approximated by a zero-phase-lag proportional autopilot with the assumption that the control surface moves instantaneously at the point where the system switches from flicker to proportional. Good correlation is shown between the results obtained by this method and results obtained by using a close approximation of an actual autopilot transfer function for proportional autopilot operation.

  8. Linearly Forced Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Lundgren, T. S.

    2003-01-01

    Stationary isotropic turbulence is often studied numerically by adding a forcing term to the Navier-Stokes equation. This is usually done for the purpose of achieving higher Reynolds number and longer statistics than is possible for isotropic decaying turbulence. It is generally accepted that forcing the Navier-Stokes equation at low wave number does not influence the small scale statistics of the flow provided that there is wide separation between the largest and smallest scales. It will be shown, however, that the spectral width of the forcing has a noticeable effect on inertial range statistics. A case will be made here for using a broader form of forcing in order to compare computed isotropic stationary turbulence with (decaying) grid turbulence. It is shown that using a forcing function which is directly proportional to the velocity has physical meaning and gives results which are closer to both homogeneous and non-homogeneous turbulence. Section 1 presents a four part series of motivations for linear forcing. Section 2 puts linear forcing to a numerical test with a pseudospectral computation.

  9. As-built design specification for proportion estimate software subsystem

    NASA Technical Reports Server (NTRS)

    Obrien, S. (Principal Investigator)

    1980-01-01

    The Proportion Estimate Processor evaluates four estimation techniques in order to get an improved estimate of the proportion of a scene that is planted in a selected crop. The four techniques to be evaluated were provided by the techniques development section and are: (1) random sampling; (2) proportional allocation, relative count estimate; (3) proportional allocation, Bayesian estimate; and (4) sequential Bayesian allocation. The user is given two options for computation of the estimated mean square error. These are referred to as the cluster calculation option and the segment calculation option. The software for the Proportion Estimate Processor is operational on the IBM 3031 computer.

  10. A note on Cohen's overlapping proportions of normal distributions.

    PubMed

    Grice, James W; Barrett, Paul T

    2014-12-01

    Social scientists are often interested in computing the proportion of overlap and nonoverlap between two normal distributions that are separated by some magnitude. In his popular book, Statistical Power Analysis for the Behavioral Sciences (1988, 2nd ed.), Jacob Cohen provided a table (Table 2.2.1) for determining such proportions from common values of separation. Unfortunately, Cohen's proportions are inconsistent with his explication of the popular index of effect size, d; and his proportions are underestimates of distributional overlap and overestimates of nonoverlap. The authors explain how Cohen derived his values and then provide a revised, corrected table of proportions that also match values presented elsewhere.

  11. Estimating sighting proportions of American alligator nests during helicopter survey

    USGS Publications Warehouse

    Rice, Kenneth G.; Percival, H. Franklin; Woodward, Allan R.

    2000-01-01

    Proportions of American alligator (Alligator mississippiensis) nests sighted during aerial survey in Florida were estimated based upon multiple surveys by different observers. We compared sighting proportions across habitats, nesting seasons, and observer experience levels. The mean sighting proportion across all habitats and years was 0.736 (SE=0.024). Survey counts corrected by the mean sighting proportion reliably predicted total nest counts (7?2=0.933). Sighting proportions did not differ by habitat type (P=0.668) or year P=0.328). Experienced observers detected a greater proportion of nests (P<0.0001) than did either less experienced or inexperienced observers. Reliable estimates of nest abundance can be derived from aerial counts of alligator nests when corrected by the appropriate sighting proportion.

  12. Students' Understanding of Proportional, Inverse Proportional, and Affine Functions: Two Studies on the Role of External Representations

    ERIC Educational Resources Information Center

    De Bock, Dirk; Van Dooren, Wim; Verschaffel, Lieven

    2015-01-01

    We investigated students' understanding of proportional, inverse proportional, and affine functions and the way this understanding is affected by various external representations. In a first study, we focus on students' ability to model textual descriptions of situations with different kinds of representations of proportional, inverse…

  13. Students' Understanding of Proportional, Inverse Proportional, and Affine Functions: Two Studies on the Role of External Representations

    ERIC Educational Resources Information Center

    De Bock, Dirk; Van Dooren, Wim; Verschaffel, Lieven

    2015-01-01

    We investigated students' understanding of proportional, inverse proportional, and affine functions and the way this understanding is affected by various external representations. In a first study, we focus on students' ability to model textual descriptions of situations with different kinds of representations of proportional, inverse…

  14. Principled Improvement in Science: Forces and Proportional Relations in Early Secondary-School Teaching

    ERIC Educational Resources Information Center

    Howe, Christine; Ilie, Sonia; Guardia, Paula; Hofmann, Riikka; Mercer, Neil; Riga, Fran

    2015-01-01

    In response to continuing concerns about student attainment and participation in science and mathematics, the "epiSTEMe" project took a novel approach to pedagogy in these two disciplines. Using principles identified as effective in the research literature (and combining these in a fashion not previously attempted), the project developed…

  15. Principled Improvement in Science: Forces and Proportional Relations in Early Secondary-School Teaching

    ERIC Educational Resources Information Center

    Howe, Christine; Ilie, Sonia; Guardia, Paula; Hofmann, Riikka; Mercer, Neil; Riga, Fran

    2015-01-01

    In response to continuing concerns about student attainment and participation in science and mathematics, the "epiSTEMe" project took a novel approach to pedagogy in these two disciplines. Using principles identified as effective in the research literature (and combining these in a fashion not previously attempted), the project developed…

  16. Lorentz force on sodium and chlorine ions in a salt water solution flow under a transverse magnetic field

    NASA Astrophysics Data System (ADS)

    DeLuca, R.

    2009-05-01

    It is shown that, by applying elementary concepts in electromagnetism and electrochemistry to a system consisting of salt water flowing in a thin rectangular pipe at an average velocity vA under the influence of a transverse magnetic field B0, an electromotive force generator can be conceived. In fact, the Lorentz force acting on the sodium and chlorine ions in a water solution gives rise to a so-called Faraday voltage across the two metal electrodes, positioned at the sides of the pipe. The effect is carried along the following chemical reactions at the electrodes: at the cathode, water is reduced (instead of sodium ions) and hydrogen gas is generated; at the anode, chlorine gas is produced. In college physics teaching, this interdisciplinary subject can be adopted to stress analogies and differences between the Hall voltage in conductors and the Faraday voltage in electrolyte solutions.

  17. Eigensolutions of non-proportionally damped systems based on continuous damping sensitivity

    NASA Astrophysics Data System (ADS)

    Lázaro, Mario

    2016-02-01

    The viscous damping model has been widely used to represent dissipative forces in structures under mechanical vibrations. In multiple degree of freedom systems, such behavior is mathematically modeled by a damping matrix, which in general presents non-proportionality, that is, it does not become diagonal in the modal space of the undamped problem. Eigensolutions of non-proportional systems are usually estimated assuming that the modal damping matrix is diagonally dominant (neglecting the off-diagonal terms) or, in the general case, using the state-space approach. In this paper, a new closed-form expression for the complex eigenvalues of non-proportionally damped system is proposed. The approach is derived assuming small damping and involves not only the diagonal terms of the modal damping matrix, but also the off-diagonal terms, which appear under higher order. The validity of the proposed approach is illustrated through a numerical example.

  18. Relationship between maxillary central incisor proportions and facial proportions.

    PubMed

    Radia, Sapna; Sherriff, Martyn; McDonald, Fraser; Naini, Farhad B

    2016-06-01

    No universally accepted parameter exists for selecting maxillary central incisors (MCIs) relative to facial proportions. The purpose of this prospective clinical study was to determine the relationship between MCIs and facial height and width in adults, intersex differences, and measurement differences between right and left MCI. A prospective study was undertaken of 149 dental students (F:76; M:73) aged between 18 and 30 years. Anthropometric MCI and horizontal and vertical facial measurements were recorded with digital calipers by 1 operator. Correlation was investigated with Pearson correlation coefficients (α=.05). Two-sample t tests were used for intersex comparisons and paired t tests to compare right and left MCIs. Intraexaminer reliability was tested by remeasuring 25 participants and applying the Bland-Altman and Lin analyses. The mean MCI height was 10.28 mm (right and left) and the mean widths were 8.65 mm (right) and 8.66 mm (left). Intersex incisor differences existed for height measurements (M:F 0.54 mm [right], 0.46 mm [left]) and width measurements (M:F 0.26 mm) but not for width-to-height ratios (F=0.85; M=0.84). A mean ratio of 15.56 was found between bizygomatic width:tooth width (M=15.75, F=15.37) and of 17.93 between total face height:MCI height (M=17.97, F=17.89). Correlation coefficients were low for all tooth:face measurements. Intraexaminer reliability was clinically acceptable. Men had larger teeth and faces but similar width:height ratios. There was no significant size difference between right and left MCI, little individual relationship between tooth:face proportions, and insignificant sex influence. The "biometric ratio"' of 1:16 for MCI:bizygomatic width was not reconfirmed exactly. A ratio of 1:18 is proposed for MCI height to total face height (Tr-Me') and 1:12 for face height (N'-Me'). Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  19. Labor Force

    ERIC Educational Resources Information Center

    Occupational Outlook Quarterly, 2012

    2012-01-01

    The labor force is the number of people ages 16 or older who are either working or looking for work. It does not include active-duty military personnel or the institutionalized population, such as prison inmates. Determining the size of the labor force is a way of determining how big the economy can get. The size of the labor force depends on two…

  20. Assessment of facial golden proportions among young Japanese women.

    PubMed

    Mizumoto, Yasushi; Deguchi, Toshio; Fong, Kelvin W C

    2009-08-01

    Facial proportions are of interest in orthodontics. The null hypothesis is that there is no difference in golden proportions of the soft-tissue facial balance between Japanese and white women. Facial proportions were assessed by examining photographs of 3 groups of Asian women: group 1, 30 young adult patients with a skeletal Class 1 occlusion; group 2, 30 models; and group 3, 14 popular actresses. Photographic prints or slides were digitized for image analysis. Group 1 subjects had standardized photos taken as part of their treatment. Photos of the subjects in groups 2 and 3 were collected from magazines and other sources and were of varying sizes; therefore, the output image size was not considered. The range of measurement errors was 0.17% to 1.16%. ANOVA was selected because the data set was normally distributed with homogeneous variances. The subjects in the 3 groups showed good total facial proportions. The proportions of the face-height components in group 1 were similar to the golden proportion, which indicated a longer, lower facial height and shorter nose. Group 2 differed from the golden proportion, with a short, lower facial height. Group 3 had golden proportions in all 7 measurements. The proportion of the face width deviated from the golden proportion, indicating a small mouth or wide-set eyes in groups 1 and 2. The null hypothesis was verified in the group 3 actresses in the facial height components. Some measurements in groups 1 and 2 showed different facial proportions that deviated from the golden proportion (ratio).

  1. Evaluation of natural smile: Golden proportion, RED or Golden percentage

    PubMed Central

    Murthy, B. V. Sreenivasan; Ramani, Niketa

    2008-01-01

    Creating geometric or mathematical proportion to relate the successive width of maxillary anterior teeth is a critical aspect in Esthetic dentistry. Golden proportion, recurring esthetic dental (RED) proportion and golden percentage are new theories in this field. Aim: To investigate the existence and suitability of Golden proportion, Recurring Esthetic Dental, and Golden percentage between the widths of maxillary anterior teeth in individuals with natural dentition, with the aid of digital photographs and computer analysis. Material and Methods: Standardized frontal images of 56 dental students, 20 male and 36 female, were captured. Each maxillary anterior tooth was digitally measured. Once the measurements were recorded, the three theories were applied and the data was analyzed statistically. Results: The golden proportion was found to exist only in 14-25% of the subjects, between perceived maxillary anterior teeth in natural dentition. The value of RED proportion was not constant, and as one moved distally, this proportion gradually increased. Furthermore, the results revealed that golden percentage was rather constant in terms of relative tooth width. Central incisor represented 22%, lateral incisor 15% and canine 13% of the width of six maxillary anterior teeth, as viewed from the front. Conclusion: Both golden proportion and RED proportion are unsuitable methods to relate the successive width of the maxillary anterior teeth in natural dentition. However, the golden percentage theory can be applied if percentages are adjusted, taking into consideration the ethnicity of the population. PMID:20142879

  2. Evaluation of natural smile: Golden proportion, RED or Golden percentage.

    PubMed

    Murthy, B V Sreenivasan; Ramani, Niketa

    2008-01-01

    Creating geometric or mathematical proportion to relate the successive width of maxillary anterior teeth is a critical aspect in Esthetic dentistry. Golden proportion, recurring esthetic dental (RED) proportion and golden percentage are new theories in this field. To investigate the existence and suitability of Golden proportion, Recurring Esthetic Dental, and Golden percentage between the widths of maxillary anterior teeth in individuals with natural dentition, with the aid of digital photographs and computer analysis. Standardized frontal images of 56 dental students, 20 male and 36 female, were captured. Each maxillary anterior tooth was digitally measured. Once the measurements were recorded, the three theories were applied and the data was analyzed statistically. The golden proportion was found to exist only in 14-25% of the subjects, between perceived maxillary anterior teeth in natural dentition. The value of RED proportion was not constant, and as one moved distally, this proportion gradually increased. Furthermore, the results revealed that golden percentage was rather constant in terms of relative tooth width. Central incisor represented 22%, lateral incisor 15% and canine 13% of the width of six maxillary anterior teeth, as viewed from the front. Both golden proportion and RED proportion are unsuitable methods to relate the successive width of the maxillary anterior teeth in natural dentition. However, the golden percentage theory can be applied if percentages are adjusted, taking into consideration the ethnicity of the population.

  3. The use of proportion by young domestic chicks (Gallus gallus).

    PubMed

    Rugani, Rosa; Vallortigara, Giorgio; Regolin, Lucia

    2015-05-01

    We investigated whether 4-day-old domestic chicks can discriminate proportions. Chicks were trained to respond, via food reinforcement, to one of the two stimuli, each characterized by different proportions of red and green areas (¼ vs. ¾). In Experiment 1, chicks approached the proportion associated with food, even if at test the spatial dispositions of the two areas were novel. In Experiment 2, chicks responded on the basis of proportion even when the testing stimuli were of enlarged dimensions, creating a conflict between the absolute positive area experienced during training and the relative proportion of the two areas. However, chicks could have responded on the basis of the overall colour (red or green) of the figures rather than proportion per se. To control for this objection, in Experiment 3, we used new pairs of testing stimuli, each depicting a different number of small squares on a white background (i.e. 1 green and 3 red vs. 3 green and 1 red or 5 green and 15 red vs. 5 red and 15 green). Chicks were again able to respond to the correct proportion, showing they discriminated on the basis of proportion of continuous quantities and not on the basis of the prevalent colour or on the absolute amount of it. Data indicate that chicks can track continuous quantities through various manipulations, suggesting that proportions are information that can be processed by very young animals.

  4. Golden proportions as predictors of attractiveness and malocclusion.

    PubMed

    Rajiv, Ahluwalia; Juhi, Yadav

    2014-01-01

    In recent years, the golden proportions have been evaluated by various researchers in the general population and orthodontic patients to establish their correlation with facial attractiveness and esthetics, but with conflicting results. The present study aimed to analyze the frontal facial golden proportions for three groups of young adult females, an attractive group, and two malocclusion groups. Our null hypothesis stated that the golden proportions of attractive females were analogous with or closer to the golden number than those with an established malocclusion. Frontal facial photographs of 80 female dental students were scored for facial attractiveness by 10 dental specialists. Thirty females with scores greater than the median score of 48 formed the attractive group. Thirteen females with Class I malocclusion and 15 females with Class II division 1 malocclusion formed the two malocclusion groups. Ten landmarks and 19 golden proportions were calculated for all subjects. One-way ANOVA and unpaired Student's t-test was used to analyze the differences in golden proportions between the attractive and malocclusion groups. Significant differences were observed for 10 proportions (P<0.04 to <0.0001). Five vertical proportions showed significant differences in both subgroups; Attractive versus Class I and Attractive versus Class II division 1; while one vertical and all transverse proportions showed significant differences only in Attractive versus Class II division 1 subgroup. The average values of these proportions varied both toward and away from the golden number for both attractive and malocclusion groups. Facial proportions of the attractive females were significantly different from those with malocclusion, but did not show a constant trend of being closer to the golden number. Furthermore, the golden proportions were not analogous with the facial esthetics of the attractive females.

  5. GEEORD: A SAS macro for analyzing ordinal response variables with repeated measures through proportional odds, partial proportional odds, or non-proportional odds models.

    PubMed

    Gao, Xiaoming; Schwartz, Todd A; Preisser, John S; Perin, Jamie

    2017-10-01

    A SAS macro, GEEORD, has been developed for the analysis of ordinal responses with repeated measures through a regression model that flexibly allows the proportional odds assumption to apply (or not) separately for each explanatory variable. Previously utilized in an analysis of a longitudinal orthognathic surgery clinical trial by Preisser et al. [1,2], the basis of GEEORD is the generalized estimating equations (GEE) method for cumulative logits models described by Lipsitz et al. [3]. The macro extends the capabilities for modeling correlated ordinal data of GEECAT, a SAS macro that allows the user to model correlated categorical response data [4]. The macro applies to independent ordinal responses as a special case. Examples are provided to demonstrate the convenient application of GEEORD to two different datasets. The macro's features are illustrated in fitting models to ordinal response variables in univariate and repeated measures settings; this includes the capacity to fit the non-proportional odds model, the partial proportional odds model, and the proportional odds model. The macro additionally provides relevant tests of the proportional odds assumption. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Force cycles and force chains.

    PubMed

    Tordesillas, Antoinette; Walker, David M; Lin, Qun

    2010-01-01

    We examine the coevolution of N cycles and force chains as part of a broader study which is designed to quantitatively characterize the role of the laterally supporting contact network to the evolution of force chains. Here, we elucidate the rheological function of these coexisting structures, especially in the lead up to failure. In analogy to force chains, we introduce the concept of force cycles: N cycles whose contacts each bear above average force. We examine their evolution around force chains in a discrete element simulation of a dense granular material under quasistatic biaxial loading. Three-force cycles are shown to be stabilizing structures that inhibit relative particle rotations and provide strong lateral support to force chains. These exhibit distinct behavior from other cycles. Their population decreases rapidly during the initial stages of the strain-hardening regime-a trend that is suddenly interrupted and reversed upon commencement of force chain buckling prior to peak shear stress. Results suggest that the three-force cycles are called upon for reinforcements to ward off failure via shear banding. Ultimately though, the resistance to buckling proves futile; buckling wins under the combined effects of dilatation and increasing compressive load. The sudden increase in three-force cycles may thus be viewed as an indicator of imminent failure via shear bands.

  7. The Failings of the Law of Definite Proportions

    ERIC Educational Resources Information Center

    Suchow, Lawrence

    1975-01-01

    Indicates that the concept of definite proportions or constant composition should be introduced with qualification. Presents arguments against the Law of Definite Proportions and cites examples in the areas of solid solutions, compounds of the transition and inner transition elements, and in some compounds of the representative elements. (GS)

  8. The Fibonacci Sequence: Proportional Semantic Bases of Children's Aesthetic Preferences.

    ERIC Educational Resources Information Center

    Neperud, Ronald W.; Serlin, Ronald C.

    1984-01-01

    Only at the third- and seventh-grade levels did proportional preferences for Fibonacci figures differ significantly from preferences for other kinds of proportional spatial divisions. Semantic patterns were similar among third and fifth graders, with a change occurring between fifth and seventh grades in keeping with the development of formal…

  9. Putative golden proportions as predictors of facial esthetics in adolescents.

    PubMed

    Kiekens, Rosemie M A; Kuijpers-Jagtman, Anne Marie; van 't Hof, Martin A; van 't Hof, Bep E; Maltha, Jaap C

    2008-10-01

    In orthodontics, facial esthetics is assumed to be related to golden proportions apparent in the ideal human face. The aim of the study was to analyze the putative relationship between facial esthetics and golden proportions in white adolescents. Seventy-six adult laypeople evaluated sets of photographs of 64 adolescents on a visual analog scale (VAS) from 0 to 100. The facial esthetic value of each subject was calculated as a mean VAS score. Three observers recorded the position of 13 facial landmarks included in 19 putative golden proportions, based on the golden proportions as defined by Ricketts. The proportions and each proportion's deviation from the golden target (1.618) were calculated. This deviation was then related to the VAS scores. Only 4 of the 19 proportions had a significant negative correlation with the VAS scores, indicating that beautiful faces showed less deviation from the golden standard than less beautiful faces. Together, these variables explained only 16% of the variance. Few golden proportions have a significant relationship with facial esthetics in adolescents. The explained variance of these variables is too small to be of clinical importance.

  10. ESTIMATING PROPORTION OF AREA OCCUPIED UNDER COMPLEX SURVEY DESIGNS

    EPA Science Inventory

    Estimating proportion of sites occupied, or proportion of area occupied (PAO) is a common problem in environmental studies. Typically, field surveys do not ensure that occupancy of a site is made with perfect detection. Maximum likelihood estimation of site occupancy rates when...

  11. Adolescent Understanding of Proportionality: The Effects of Task Characteristics.

    ERIC Educational Resources Information Center

    Abramowitz, Susan

    This study examines the effects of using different classes of ratios on adolescent performance on proportionality problems. Problems of the form a/b = c/x varied on four dimensions: size of a/b, equality or inequality of b and c, complex or simple fractions, and form of the test. Tests consisted of six proportionality problems involving sizes of…

  12. Understanding Proportional Reasoning in Pre-Service Teachers

    ERIC Educational Resources Information Center

    Johnson, Kim H.

    2013-01-01

    The purpose of this study is to examine the proportional reasoning of pre-service teachers at the beginning of their teacher preparation program using the developmental shifts described by Lobato and Ellis (2010). They cast changes in proportional reasoning as transitions or "shifts" in students' thinking and these shifts can serve as…

  13. The influence of lower face vertical proportion on facial attractiveness.

    PubMed

    Johnston, D J; Hunt, O; Johnston, C D; Burden, D J; Stevenson, M; Hepper, P

    2005-08-01

    This study investigated the influence of changing lower face vertical proportion on the attractiveness ratings scored by lay people.Ninety-two social science students rated the attractiveness of a series of silhouettes with normal, reduced or increased lower face proportions. The random sequences of 10 images included an image with the Eastman normal lower face height relative to total face height [lower anterior face height/total anterior face height (LAFH/TAFH) of 55 per cent], and images with LAFH/TAFH increased or decreased by up to four standard deviations (SD) from the Eastman norm. All the images had a skeletal Class I antero-posterior (AP) relationship. A duplicate image in each sequence assessed repeatability. The participants scored each image using a 10 point numerical scale and also indicated whether they would seek treatment if the image was their own profile. The profile image with normal vertical facial proportions was rated by the lay people as the most attractive. Attractiveness scores reduced as the vertical facial proportions diverged from the normal value. Images with a reduced lower face proportion were rated as significantly more attractive than the corresponding images with an increased lower face proportion. Images with a reduced lower face proportion were also significantly less likely to be judged as needing treatment than the corresponding images with an increased lower face proportion.

  14. 16 CFR 240.9 - Proportionally equal terms.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Proportionally equal terms. 240.9 Section 240.9 Commercial Practices FEDERAL TRADE COMMISSION GUIDES AND TRADE PRACTICE RULES GUIDES FOR ADVERTISING ALLOWANCES AND OTHER MERCHANDISING PAYMENTS AND SERVICES § 240.9 Proportionally equal terms. (a...

  15. An investigation of condition mapping and plot proportion calculation issues

    Treesearch

    Demetrios Gatziolis

    2007-01-01

    A systematic examination of Forest Inventory and Analysis condition data collected under the annual inventory protocol in the Pacific Northwest region between 2000 and 2004 revealed the presence of errors both in condition topology and plot proportion computations. When plots were compiled to generate population estimates, proportion errors were found to cause...

  16. The Failings of the Law of Definite Proportions

    ERIC Educational Resources Information Center

    Suchow, Lawrence

    1975-01-01

    Indicates that the concept of definite proportions or constant composition should be introduced with qualification. Presents arguments against the Law of Definite Proportions and cites examples in the areas of solid solutions, compounds of the transition and inner transition elements, and in some compounds of the representative elements. (GS)

  17. A Pre-Chemistry Course on Proportional Calculations.

    ERIC Educational Resources Information Center

    Goodstein, Madeline P.; Boelke, William W.

    Reported are results from a pilot study evaluating the effectiveness of a high school mathematics course on the applications of proportional calculations for students subsequently enrolled in chemistry. Two effects were investigated: (1) the effect of the course on students' ability to do proportional calculations not explicitly involving chemical…

  18. Understanding Proportional Reasoning in Pre-Service Teachers

    ERIC Educational Resources Information Center

    Johnson, Kim H.

    2013-01-01

    The purpose of this study is to examine the proportional reasoning of pre-service teachers at the beginning of their teacher preparation program using the developmental shifts described by Lobato and Ellis (2010). They cast changes in proportional reasoning as transitions or "shifts" in students' thinking and these shifts can serve as…

  19. Longitudinal Enrollment Dynamics and Changes in Ethnic Proportionality.

    ERIC Educational Resources Information Center

    Greaves, Fred

    The Federal Racial/Ethnic Surveys of the Salinas Union High School District were examined to identify changes in ethnic proportions within a particular class from its entry in the 9th grade until the 12th grade. The 9th, 10th, 11th, and 12th grade proportional distributions are reported by school (Alisal High School, North Salinas High School, and…

  20. The Improved Estimation of Ratio of Two Population Proportions

    ERIC Educational Resources Information Center

    Solanki, Ramkrishna S.; Singh, Housila P.

    2016-01-01

    In this article, first we obtained the correct mean square error expression of Gupta and Shabbir's linear weighted estimator of the ratio of two population proportions. Later we suggested the general class of ratio estimators of two population proportions. The usual ratio estimator, Wynn-type estimator, Singh, Singh, and Kaur difference-type…

  1. Attention Modulation by Proportion Congruency: The Asymmetrical List Shifting Effect

    ERIC Educational Resources Information Center

    Abrahamse, Elger L.; Duthoo, Wout; Notebaert, Wim; Risko, Evan F.

    2013-01-01

    Proportion congruency effects represent hallmark phenomena in current theorizing about cognitive control. This is based on the notion that proportion congruency determines the relative levels of attention to relevant and irrelevant information in conflict tasks. However, little empirical evidence exists that uniquely supports such an attention…

  2. Recommended confidence intervals for two independent binomial proportions.

    PubMed

    Fagerland, Morten W; Lydersen, Stian; Laake, Petter

    2015-04-01

    The relationship between two independent binomial proportions is commonly estimated and presented using the difference between proportions, the number needed to treat, the ratio of proportions or the odds ratio. Several different confidence intervals are available, but they can produce markedly different results. Some of the traditional approaches, such as the Wald interval for the difference between proportions and the Katz log interval for the ratio of proportions, do not perform well unless the sample size is large. Better intervals are available. This article describes and compares approximate and exact confidence intervals that are - with one exception - easy to calculate or available in common software packages. We illustrate the performances of the intervals and make recommendations for both small and moderate-to-large sample sizes. © The Author(s) 2011 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  3. Nuclear Quantum Gravitation - Forces Unification

    NASA Astrophysics Data System (ADS)

    Kotas, Ronald

    2017-01-01

    With Nuclear Quantum Gravitation, the Forces are plainly and coherently unified. This most certainly is the missing link in Newtonian Gravitation explaining clearly the internal workings based in the Atomic Nucleus. The gravitational force between two gravitating masses is because of alternating electromagnetic functions in nuclei in matter. The Cavendish Experiment - Demonstration clearly shows the Gravitational attraction between two masses, which is a force proportional to the Newtonian Mechanics. General Relativity fails this real, physical test. Nuclear Quantum Gravitation has 10 logical proofs and 21 more indications. It is Scientifically logical and is compatible with Quantum Mechanics and Newtonian Mechanics.

  4. Development of proportional reasoning: where young children go wrong.

    PubMed

    Boyer, Ty W; Levine, Susan C; Huttenlocher, Janellen

    2008-09-01

    Previous studies have found that children have difficulty solving proportional reasoning problems involving discrete units until 10 to 12 years of age, but can solve parallel problems involving continuous quantities by 6 years of age. The present studies examine where children go wrong in processing proportions that involve discrete quantities. A computerized proportional equivalence choice task was administered to kindergartners through 4th-graders in Study 1, and to 1st- and 3rd-graders in Study 2. Both studies involved 4 between-subjects conditions that were formed by pairing continuous and discrete target proportions with continuous and discrete choice alternatives. In Study 1, target and choice alternatives were presented simultaneously; in Study 2, target and choice alternatives were presented sequentially. In both studies, children performed significantly worse when both the target and choice alternatives were represented with discrete quantities than when either or both of the proportions involved continuous quantities. Taken together, these findings indicate that children go astray on proportional reasoning problems involving discrete units only when a numerical match is possible, suggesting that their difficulty is due to an overextension of numerical equivalence concepts to proportional equivalence problems.

  5. Development of Proportional Reasoning: Where Young Children Go Wrong

    PubMed Central

    Boyer, Ty W.; Levine, Susan C.; Huttenlocher, Janellen

    2008-01-01

    Previous studies have found that children have difficulty solving proportional reasoning problems involving discrete units until 10- to 12-years of age, but can solve parallel problems involving continuous quantities by 6-years of age. The present studies examine where children go wrong in processing proportions that involve discrete quantities. A computerized proportional equivalence choice task was administered to kindergartners through fourth-graders in Study 1, and to first- and third-graders in Study 2. Both studies involved four between-subjects conditions that were formed by pairing continuous and discrete target proportions with continuous and discrete choice alternatives. In Study 1, target and choice alternatives were presented simultaneously and in Study 2 target and choice alternatives were presented sequentially. In both studies, children performed significantly worse when both the target and choice alternatives were represented with discrete quantities than when either or both of the proportions involved continuous quantities. Taken together, these findings indicate that children go astray on proportional reasoning problems involving discrete units only when a numerical match is possible, suggesting that their difficulty is due to an overextension of numerical equivalence concepts to proportional equivalence problems. PMID:18793078

  6. Labor Force

    ERIC Educational Resources Information Center

    Occupational Outlook Quarterly, 2010

    2010-01-01

    The labor force is the number of people aged 16 or older who are either working or looking for work. It does not include active-duty military personnel or institutionalized people, such as prison inmates. Quantifying this total supply of labor is a way of determining how big the economy can get. Labor force participation rates vary significantly…

  7. Casimir force between hyperbolic metamaterials

    NASA Astrophysics Data System (ADS)

    Song, Ge; Xu, Jingping; Zhu, Chengjie; He, Pengfei; Yang, Yaping; Zhu, Shi-Yao

    2017-02-01

    The Casimir force between two hyperbolic metamaterials (HMMs) constructed by alternative metal-dielectric layers is investigated. Due to the existence of the hyperbolic dispersion, the electromagnetic response of HMMs becomes extremely dramatic, which is embodied by the nearly total reflection in such frequency region. As a result, the Casimir force between HMMs is much greater than that between ordinary dielectrics. In addition, it is shown that the Casimir force is proportional to the bandwidth of this hyperbolic dispersion, which is dependent on the filling factor as well as the characteristic frequencies of ingredient materials. Therefore, the relations between the force and these parameters are discussed. We show that the Casimir force can be controlled by tuning the bandwidth possessing hyperbolic dispersion of the structures. This work provides promising applications of HMMs on microelectromechanical systems and nanoelectromechanical systems.

  8. Improvements in estimating proportions of objects from multispectral data

    NASA Technical Reports Server (NTRS)

    Horwitz, H. M.; Hyde, P. D.; Richardson, W.

    1974-01-01

    Methods for estimating proportions of objects and materials imaged within the instantaneous field of view of a multispectral sensor were developed further. Improvements in the basic proportion estimation algorithm were devised as well as improved alien object detection procedures. Also, a simplified signature set analysis scheme was introduced for determining the adequacy of signature set geometry for satisfactory proportion estimation. Averaging procedures used in conjunction with the mixtures algorithm were examined theoretically and applied to artificially generated multispectral data. A computationally simpler estimator was considered and found unsatisfactory. Experiments conducted to find a suitable procedure for setting the alien object threshold yielded little definitive result. Mixtures procedures were used on a limited amount of ERTS data to estimate wheat proportion in selected areas. Results were unsatisfactory, partly because of the ill-conditioned nature of the pure signature set.

  9. Proportionality: a valid alternative to correlation for relative data.

    PubMed

    Lovell, David; Pawlowsky-Glahn, Vera; Egozcue, Juan José; Marguerat, Samuel; Bähler, Jürg

    2015-03-01

    In the life sciences, many measurement methods yield only the relative abundances of different components in a sample. With such relative-or compositional-data, differential expression needs careful interpretation, and correlation-a statistical workhorse for analyzing pairwise relationships-is an inappropriate measure of association. Using yeast gene expression data we show how correlation can be misleading and present proportionality as a valid alternative for relative data. We show how the strength of proportionality between two variables can be meaningfully and interpretably described by a new statistic ϕ which can be used instead of correlation as the basis of familiar analyses and visualisation methods, including co-expression networks and clustered heatmaps. While the main aim of this study is to present proportionality as a means to analyse relative data, it also raises intriguing questions about the molecular mechanisms underlying the proportional regulation of a range of yeast genes.

  10. Proportionality: A Valid Alternative to Correlation for Relative Data

    PubMed Central

    Lovell, David; Pawlowsky-Glahn, Vera; Egozcue, Juan José; Marguerat, Samuel; Bähler, Jürg

    2015-01-01

    In the life sciences, many measurement methods yield only the relative abundances of different components in a sample. With such relative—or compositional—data, differential expression needs careful interpretation, and correlation—a statistical workhorse for analyzing pairwise relationships—is an inappropriate measure of association. Using yeast gene expression data we show how correlation can be misleading and present proportionality as a valid alternative for relative data. We show how the strength of proportionality between two variables can be meaningfully and interpretably described by a new statistic ϕ which can be used instead of correlation as the basis of familiar analyses and visualisation methods, including co-expression networks and clustered heatmaps. While the main aim of this study is to present proportionality as a means to analyse relative data, it also raises intriguing questions about the molecular mechanisms underlying the proportional regulation of a range of yeast genes. PMID:25775355

  11. Proportion effect in diblock co-oligomer molecular diodes

    NASA Astrophysics Data System (ADS)

    Hu, G. C.; Zhang, G. P.; Li, Y.; Ren, J. F.; Wang, C. K.

    2014-10-01

    Based on ab-initio theory and nonequilibrium Green's function method, the effect of proportion on the rectification in pyrimidinyl-phenyl diblock co-oligomer diodes is investigated in two regimes. For a short co-oligomer diode, it is found that the 1:1 proportion of the two moieties favors the largest rectification ratio. For a long co-oligomer diode, an interesting proportion-dependent variation of the rectifying direction is observed. Furthermore, the optimal proportion for the largest rectification ratio is not 1:1 any longer. A deep understanding can be achieved by analyzing the bias-dependent transmission spectra combined with the evolution of the molecular orbitals.

  12. Further studies of proportional electroluminescence in two-phase argon

    NASA Astrophysics Data System (ADS)

    Bondar, A.; Buzulutskov, A.; Dolgov, A.; Frolov, E.; Nosov, V.; Oleynikov, V.; Shekhtman, L.; Shemyakina, E.; Sokolov, A.

    2017-05-01

    A study of proportional electroluminescence in two-phase argon is relevant in the field of noble-gas liquid detectors for dark matter search and low-energy neutrino experiments. In this work, we continued to study proportional electroluminescence (EL) in two-phase argon doped with a minor (9 ppm) admixture of nitrogen, in the VUV, UV and visible spectral ranges. We confirmed the effect of enhancement of the EL yield, as well as the presence of a non-VUV component in addition to that of VUV, in proportional electroluminescence in two-phase Ar. On the other hand, the contribution of the non-VUV component determined here within the model of N2 emission in the UV, turned out to be insufficient to explain the enhancement of the EL yield. Hence, the problem of proportional electroluminescence in two-phase Ar remains unresolved.

  13. DC motor proportional control system for orthotic devices

    NASA Technical Reports Server (NTRS)

    Blaise, H. T.; Allen, J. R.

    1972-01-01

    Multi-channel proportional control system for operation of dc motors for use with externally-powered orthotic arm braces is described. Components of circuitry and principles of operation are described. Schematic diagram of control circuit is provided.

  14. Operability test report for 211BA flow proportional sampler

    SciTech Connect

    Weissenfels, R.D.

    1995-01-01

    This operability report will verify that the 211-BA flow proportional sampler functions as intended by design. The sampler was installed by Project W-007H and is part of BAT/AKART for the BCE liquid effluent stream.

  15. A Weighted Harmonic Means Analysis for the Proportional Unbalanced Design.

    ERIC Educational Resources Information Center

    Bonett, Douglas G.

    1982-01-01

    A weighted harmonic means analysis is presented that incorporates all of the available data, preserves the planned proportionality of the design, and avoids the problems associated with the replacement of missing data with sample estimates. (Author/BW)

  16. Effect of mixed (boundary) pixels on crop proportion estimation

    NASA Technical Reports Server (NTRS)

    Chhikara, R. S.

    1984-01-01

    In estimating acreage proportions of crop types in a segment using Landsat data, considerable problem is caused by the presence of mixed pixels. Due to lack of understanding of their spectral characteristics, mixed pixels have been treated in the past as pure while clustering and classifying the segment data. This paper examines this approach of treating mixed pixels as pure pixels and the effect of mixed pixels on the bias and variance of a crop type proportion estimate. First, the spectral response of a boundary pixel is modeled and an analytical expression for the bias and variance of a proportion estimate is obtained. This is followed by a numerical illustration of the effect of mixed pixels on bias and variance. It is shown that as the size of the mixed pixel class increases in a segment, the variance increases, however, such increase does not always affect the bias of the proportion estimate.

  17. Comparison of proportions for composite endpoints with missing components.

    PubMed

    Li, Xianbin; Caffo, Brian S

    2011-03-01

    Composite endpoints are commonly used in clinical trials. When there are missing values in their individual components, inappropriate handling of the missingness may create inefficient or even biased estimates of the proportions of successes in composite endpoints. Assuming missingness is completely at random or dependent on baseline covariates, we derived a maximum likelihood estimator of the proportion of successes in a three-component composite endpoint and closed-form variance for the proportion, and compared two groups in the difference in proportions and in the logarithm of a relative risk. Sample size and statistical power were studied. Simulation studies were used to evaluate the performance of the developed methods. With a moderate sample size the developed methods works satisfactorily.

  18. Statistical distribution of the difference of two proportions.

    PubMed

    Nadarajah, Saralees; Kotz, Samuel

    2007-08-15

    Differences of two proportions or rates occur most frequently in biomedical research. However, as far as published work in the Statistics in Medicine are concerned, only approximations have been used to study the distribution of such differences. In this Letter, we derive the exact probability distribution of the difference of two proportions. The expression involves a well-known special function. It is expected that this result could be widely useful for medical practitioners.

  19. A Gas Proportional Scintillation Counter with krypton filling

    NASA Astrophysics Data System (ADS)

    Monteiro, C. M. B.; Mano, R. D. P.; Barata, E. C. G. M.; Fernandes, L. M. P.; Freitas, E. D. C.

    2016-12-01

    A Gas Proportional Scintillation Counter filled with pure krypton was studied. Energy resolution below 10% for 5.9-keV X-rays was obtained with this prototype. This value is much better than the energy resolution obtained with proportional counters or other MPGDs with krypton filling. The krypton electroluminescence scintillation and ionisation thresholds were found to be about 0.5 and 3.5 kV cm-1bar-1, respectively.

  20. Proportional reasoning in the learning of chemistry: levels of complexity

    NASA Astrophysics Data System (ADS)

    Ramful, Ajay; Narod, Fawzia Bibi

    2014-03-01

    This interdisciplinary study sketches the ways in which proportional reasoning is involved in the solution of chemistry problems, more specifically, problems involving quantities in chemical reactions (commonly referred to as stoichiometry problems). By building on the expertise of both mathematics and chemistry education research, the present paper shows how the theoretical constructs in proportional reasoning in mathematics education offer rich explanatory accounts of the complexities involved in solving stoichiometry problems. Using Vergnaud's concept of measure spaces, the theoretical analysis shows that proportionality situations are relatively more intricate, involving various layers of complexity in chemistry as compared to those in the mathematics curriculum. Knowledge of proportionality and chemistry are simultaneously required to provide solutions to chemical reactions. Our analysis of a range of stoichiometry situations led us to propose a problem analysis framework involving five levels of difficulty. Further, the specificity of proportionality in stoichiometry is that it can only be established when quantities are interpreted in the unit "mole," a unit which does not have any physical embodiment in terms of a measure of quantity unlike mass and volume. Our analysis of student-teachers' solution to the stoichiometry problems, shows that they tend to incorrectly (probably intuitively) set proportional relationships when two quantities in a reaction are expressed in non-molar quantities such as mass. The data also bring to the fore the primarily formulaic approach that student-teachers use in setting inherent proportionality relationships. An important finding is the interpretation of a chemical equation as a mathematical equation, rather than a statement of proportionality.

  1. Proportional liquid-nitrogen valve and control system

    NASA Astrophysics Data System (ADS)

    Christman, S. B.

    1990-09-01

    A proportional magnetic valve has been developed that permits continuous flow of cryogenic fluids and gases. The proportional valve (PV) may be electrically controlled in the manual mode (open loop current drive) or in the automatic mode (closed loop current drive). A complete control system for liquid-nitrogen (LN) flow control applications is described. The system includes alarm and automatic supply tank switching features.

  2. Musculoskeletal Proportionality, Biomechanical Considerations, and Their Contribution to Movement in Adults and Children.

    PubMed

    O'Brien, Thomas D

    2016-05-01

    The musculoskeletal system grows greatly throughout maturation. When trying to explain differences in strength, power and movement patterns between adults and children many pediatric exercise scientists will assume that this growth is proportional in all dimensions and structures. This article examines the evidence underpinning these assumptions, and considers how changes in fascicle, muscle, tendon and joint proportions may contribute to maturation-induced changes in physical performance. There are only a small number of studies to draw upon, but they consistently indicate that 1) growth changes the functional design of muscles, so that they become better at producing large forces at slow speeds but less able to achieve large length changes or high velocities; 2) the skeleton appears to grow somewhat proportionally before puberty, but this changes throughout adolescence, meaning the moment arm about which the muscle acts does not remain proportional to muscle length or the external moment arm about which joint work acts on the external world. In combination these results show that external measures of whole body or joint performance do not reflect the actual internal muscle function similarly in children and adults. Since our purpose should be to explain and not just describe maturation-induced changes in performance, greater efforts are needed to understand the internal "engine" driving our movement. This necessitates more detailed, longitudinal and dynamically loaded studies of the structure and function of the muscles and their interaction with the skeleton throughout maturation.

  3. Force sensor

    DOEpatents

    Grahn, Allen R.

    1993-01-01

    A force sensor and related method for determining force components. The force sensor includes a deformable medium having a contact surface against which a force can be applied, a signal generator for generating signals that travel through the deformable medium to the contact surface, a signal receptor for receiving the signal reflected from the contact surface, a generation controller, a reception controller, and a force determination apparatus. The signal generator has one or more signal generation regions for generating the signals. The generation controller selects and activates the signal generation regions. The signal receptor has one or more signal reception regions for receiving signals and for generating detections signals in response thereto. The reception controller selects signal reception regions and detects the detection signals. The force determination apparatus measures signal transit time by timing activation and detection and, optionally, determines force components for selected cross-field intersections. The timer which times by activation and detection can be any means for measuring signal transit time. A cross-field intersection is defined by the overlap of a signal generation region and a signal reception region.

  4. Force sensor

    DOEpatents

    Grahn, A.R.

    1993-05-11

    A force sensor and related method for determining force components is described. The force sensor includes a deformable medium having a contact surface against which a force can be applied, a signal generator for generating signals that travel through the deformable medium to the contact surface, a signal receptor for receiving the signal reflected from the contact surface, a generation controller, a reception controller, and a force determination apparatus. The signal generator has one or more signal generation regions for generating the signals. The generation controller selects and activates the signal generation regions. The signal receptor has one or more signal reception regions for receiving signals and for generating detections signals in response thereto. The reception controller selects signal reception regions and detects the detection signals. The force determination apparatus measures signal transit time by timing activation and detection and, optionally, determines force components for selected cross-field intersections. The timer which times by activation and detection can be any means for measuring signal transit time. A cross-field intersection is defined by the overlap of a signal generation region and a signal reception region.

  5. Empirical study of alginate impression materials by customized proportioning system.

    PubMed

    Kurtulus, Karani; Tüfekci, Kenan

    2016-10-01

    Alginate mixers available in the market do not have the automatic proportioning unit. In this study, an automatic proportioning unit for the alginate mixer and controller software were designed and produced for a new automatic proportioning unit. With this device, it was ensured that proportioning operation could arrange weight-based alginate impression materials. The variation of coefficient in the tested groups was compared with the manual proportioning. Compression tension and tear tests were conducted to determine the mechanical properties of alginate impression materials. The experimental data were statistically analyzed using one way ANOVA and Tukey test at the 0.05 level of significance. No statistically significant differences in modulus of elastisity (P>0.3), tensional/compresional strength (P>0.3), resilience (P>0.2), strain in failure (P>0.4), and tear energy (P>0.7) of alginate impression materials were seen. However, a decrease in the standard deviation of tested groups was observed when the customized machine was used. To verify the efficiency of the system, powder and powder/water mixing were weighed and significant decrease was observed. It was possible to obtain more mechanically stable alginate impression materials by using the custom-made proportioning unit.

  6. Empirical study of alginate impression materials by customized proportioning system

    PubMed Central

    2016-01-01

    PURPOSE Alginate mixers available in the market do not have the automatic proportioning unit. In this study, an automatic proportioning unit for the alginate mixer and controller software were designed and produced for a new automatic proportioning unit. With this device, it was ensured that proportioning operation could arrange weight-based alginate impression materials. MATERIALS AND METHODS The variation of coefficient in the tested groups was compared with the manual proportioning. Compression tension and tear tests were conducted to determine the mechanical properties of alginate impression materials. The experimental data were statistically analyzed using one way ANOVA and Tukey test at the 0.05 level of significance. RESULTS No statistically significant differences in modulus of elastisity (P>0.3), tensional/compresional strength (P>0.3), resilience (P>0.2), strain in failure (P>0.4), and tear energy (P>0.7) of alginate impression materials were seen. However, a decrease in the standard deviation of tested groups was observed when the customized machine was used. To verify the efficiency of the system, powder and powder/water mixing were weighed and significant decrease was observed. CONCLUSION It was possible to obtain more mechanically stable alginate impression materials by using the custom-made proportioning unit. PMID:27826387

  7. Detecting neutrino magnetic moments with conducting loops

    NASA Astrophysics Data System (ADS)

    Apyan, Aram; Apyan, Armen; Schmitt, Michael

    2008-02-01

    It is well established that neutrinos have mass, yet it is very difficult to measure those masses directly. Within the standard model of particle physics, neutrinos will have an intrinsic magnetic moment proportional to their mass. We examine the possibility of detecting the magnetic moment using a conducting loop. According to Faraday’s law of induction, a magnetic dipole passing through a conducting loop induces an electromotive force in the loop. We compute this electromotive force for neutrinos in several cases, based on a fully covariant formulation of the problem. We discuss prospects for a real experiment, as well as the possibility to test the relativistic formulation of intrinsic magnetic moments.

  8. Chiral drag force

    NASA Astrophysics Data System (ADS)

    Rajagopal, Krishna; Sadofyev, Andrey V.

    2015-10-01

    We provide a holographic evaluation of novel contributions to the drag force acting on a heavy quark moving through strongly interacting plasma. The new contributions are chiral in the sense that they act in opposite directions in plasmas containing an excess of left- or right-handed quarks. The new contributions are proportional to the coefficient of the axial anomaly, and in this sense also are chiral. These new contributions to the drag force act either parallel to or antiparallel to an external magnetic field or to the vorticity of the fluid plasma. In all these respects, these contributions to the drag force felt by a heavy quark are analogous to the chiral magnetic effect (CME) on light quarks. However, the new contribution to the drag force is independent of the electric charge of the heavy quark and is the same for heavy quarks and antiquarks, meaning that these novel effects do not in fact contribute to the CME current. We show that although the chiral drag force can be non-vanishing for heavy quarks that are at rest in the local fluid rest frame, it does vanish for heavy quarks that are at rest in a suitably chosen frame. In this frame, the heavy quark at rest sees counterpropagating momentum and charge currents, both proportional to the axial anomaly coefficient, but feels no drag force. This provides strong concrete evidence for the absence of dissipation in chiral transport, something that has been predicted previously via consideration of symmetries. Along the way to our principal results, we provide a general calculation of the corrections to the drag force due to the presence of gradients in the flowing fluid in the presence of a nonzero chemical potential. We close with a consequence of our result that is at least in principle observable in heavy ion collisions, namely an anticorrelation between the direction of the CME current for light quarks in a given event and the direction of the kick given to the momentum of all the heavy quarks and

  9. [Research on proportional control system of prosthetic hand based on FMG signals].

    PubMed

    Yi, Jinhua; Yu, Hongliu; Li, Panpan; Zhao, Shengnan

    2013-02-01

    The control of prosthetic hand is always a focus in prosthesis research. For solving current problems of controlling signals of skin surface electrical signals, we applied force myography (FMG) signals in prosthetic control of this system. The control system based on FMG signals were designed, containing signal acquisition and pre-processing, prosthetic control, motor driving and so on. Two-freedom artificial hand with proportional control was proposed through acquiring two-channel FMG signals from the amputee stump. The proportional control of prosthetic hand was achieved according to the average of FMG amplitude. The results showed that the control system had a great potential to control artificial hand and to realize speed adjustment effectively. Besides, the Virtual instrument software LabVIEW is adopted to establish the FMG signal collection and calibration of experiment system.

  10. Prediction and measurement of the proportionality constant in statistical energy analysis of structures.

    NASA Technical Reports Server (NTRS)

    Lotz, R.; Crandall, S. H.

    1973-01-01

    The fundamental equation of statistical energy analysis (SEA) states that the average power flow between two coupled vibrating systems is proportional to the difference in their average modal energies. Under certain circumstances it is possible to estimate the proportionality constant by modifying system boundary conditions on the separated systems and calculating or measuring changes in the systems. Newland's estimate, based upon blocking part of the system, is reexamined, and limitations are discussed. Three alternative methods which circumvent blocking are presented. These were applied to predict power flow in experiments on coupled beams and on coupled plates wherein power flow through the coupling was measured directly as a product of force times velocity. The measurements support the fundamental SEA relation, including the null power point where the average modal energies are equal.

  11. Nepalese Esthetic Dental (NED) Proportion in Nepalese Population.

    PubMed

    Rokaya, D; Kitisubkanchana, J; Wonglamsam, A; Santiwong, P; Srithavaj, T; Humagain, M

    2015-01-01

    Background Lots of studies on maxillary anterior teeth proportions have been studied in different populations in various countries, but no studies have been conducted in Nepal on the esthetic maxillary anterior teeth proportions. Objective The study was done to investigate the maxillary anterior teeth proportions in a Nepalese population. Teeth proportions in the total population were compared with golden proportion (GP) and golden standard (GS). Method A total of 150 Nepalese subjects were divided in three facial types; broad, average and narrow group. Maxillary anterior teeth were measured from dental casts using digital calipers. The perceived width ratios of lateral to central incisor (LI/CI) and canine to lateral incisor (CN/LI), ratios of mean central incisor length to 2 central incisor widths (CIL/2CIW), and actual width to length ratios (WLRs) (%) were calculated in each facial type and compared. Mean LI/CI, CN/LI and CIL/2CIW in total population were calculated and compared with GP (0.618), and mean WLRs in the total population were compared with GS (80%). All teeth proportions were compared among three facial types. One-sample t-test and one-way ANOVA were performed to analyze the data (α = 0.05). Result The LI/CI, CN/LI, CIL/2CIW and WLRs in three facial types showed no significant difference. The LI/CI, CN/LI and CIL/2CIW in the total population were 66%, 70% and 55% respectively, and were significantly different from GP. The WLRs for CI, LI and CN in the total population were 90%, 86% and 89% respectively and significantly differed from GS. These values were considered to constitute the Nepalese Esthetic Dental (NED) proportion. Conclusion No significant difference of maxillary anterior teeth proportions were observed among three facial types. Teeth proportions in the total population significantly differed from GP and GS. We propose the NED proportion as a guideline for dental treatment in the maxillary anterior region in Nepalese populations.

  12. ["Golden proportion" and its application to calculate dentition].

    PubMed

    Vadachkoriia, N R; Gumberidze, N Sh; Mandzhavidze, N A

    2007-01-01

    Within an evolutionary process, the nature has created the standard of aesthetics - a "gold proportion" on the basis of which, the parts of human body, to be more exact, teeth and denture correspond to each other and to own parts by the size, which is the ideal precondition for ideal appearance. The charming smile serves as the proof, that teeth in denture are located by a principle of "gold proportion". A "gold proportion" is the corner stone of beauty and it can be applied with success in stomatology. Proportion is the certain ratio between parts, and proportional means a proper correlation of parts among themselves. It is reputed, that knowledge about "gold proportion" Pythagor has got from products of the Egyptian and Babylon scientists. And this is true, proportions of cult constructions, bas-relieves, pyramids in Giza, home appliances and ornaments from Tutanhamon tomb testify, that under their creation the Egyptian masters were guided by a principle of "gold proportion". The facade of ancient Greek temple Parthenon is built by a principle of "gold proportion". During archeological digs of this temple the compasses which sculptors and architects of an ancient world used has been found. The "gold proportion" is mentioned in the work which has reached us "Beginning" the author is the scientist of antique epoch Euclid. In 1509, in Venice the book of Luka Pacholi the "Divine proportion" has been published, its illustration is attributed to Leonardo de Vinci. This work has been recognized as a "Hymn of a gold proportion". In 1885 the German researcher professor Zeising published his work - "Aesthetic researches". When Zeising has received numerical values of piece length, he saw that they coincided with figures of some numerical sequence, which was offered by the great Italian mathematician of Middle Ages Fibonacci (or Leonardo Pisano). In his composition the "Abacus Book" Leonardo Fibonacci showed aforesaid sequence of numbers, by means of which he has explained

  13. Parameter tuning method for dither compensation of a pneumatic proportional valve with friction

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Song, Yang; Huang, Leisheng; Fan, Wei

    2016-05-01

    In the practical application of pneumatic control devices, the nonlinearity of a pneumatic control valve become the main factor affecting the control effect, which comes mainly from the dynamic friction force. The dynamic friction inside the valve may cause hysteresis and a dead zone. In this paper, a dither compensation mechanism is proposed to reduce negative effects on the basis of analyzing the mechanism of friction force. The specific dither signal (using a sinusoidal signal) was superimposed on the control signal of the valve. Based on the relationship between the parameters of the dither signal and the inherent characteristics of the proportional servo valve, a parameter tuning method was proposed, which uses a displacement sensor to measure the maximum static friction inside the valve. According to the experimental results, the proper amplitude ranges are determined for different pressures. In order to get the optimal parameters of the dither signal, some dither compensation experiments have been carried out on different signal amplitude and gas pressure conditions. Optimal parameters are determined under two kinds of pressure conditions. Using tuning parameters the valve spool displacement experiment has been taken. From the experiment results, hysteresis of the proportional servo valve is significantly reduced. And through simulation and experiments, the cut-off frequency of the proportional valve has also been widened. Therefore after adding the dither signal, the static and dynamic characteristics of the proportional valve are both improved to a certain degree. This research proposes a parameter tuning method of dither signal, and the validity of the method is verified experimentally.

  14. Proportional counter for X-ray analysis of lunar and planetary surfaces. [a position sensitive scintillating imaging proportional counter

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A position sensitive proportional scintillation detector was developed and evaluated for use in applications involving X-ray imaging as well as spectroscopy. Topics covered include limitations of the proportional scintillation counter for use in space; purification of the xenon gas in the detector, and the operation of the detector system. Results show that the light signal in a proportional scintillation detector remains well localized. With modest electric fields in xenon, the primary electrons from a photoelectric absorption of an X-ray can be brought a distance of a few millimeters to a higher field region without spreading more than a millimeter or so. Therefore, it is possible to make a proportional scintillation detector with good position sensitivity that could be used to calibrate out the difference in light collection over its sensitive volume.

  15. Assessment of facial golden proportions among central Indian population

    PubMed Central

    Saurabh, Rathore; Piyush, Bolya; Sourabh, Bhatt; Preeti, Ojha; Trivedi, Rutvik; Vishnoi, Pradeep

    2016-01-01

    Aim: This study aimed to identify and establish the facial and smile proportions in young adults and to compare the results with ideal or divine proportions, compare the proportions of males and females included in our study population and compare them with those established for Caucasian and Japanese populations. Materials and Methods: Two hundred participants (164 females, 36 males) with Angle's class I malocclusion (M.O). and well-balanced faces were selected and photographed in the frontal repose position. Analysis was done in Adobe Photoshop software. Statistical analysis was done using the Statistical Package for the Social Sciences version 17.0. (IBM Corporation Armonk, New York, United States). Results: Results suggested that females are more near to ideal ratios and males are more deviated from the ideal ratios. The proportions of males and females were not considerably different from each other. In Indian population, upper 3rd facial height (TR-LC) was increased and mid-face height (LC-LN) was decreased; in lower 3rd of the face, LN-CH was slightly increased in comparison to CH-ME. In facial widths, outer canthal width (LC-LC) was greater in the Indian population and mouth width (CH-CH) was normal. When compared with Indian population, Japanese participants had wider noses, outer canthal distance, and bitemporal width. Conclusion: It was concluded that significant difference was found between the proportions of the Indian population and ideal ratio. When Indian population was compared with Japanese and Caucasian populations, some parameters of facial proportions showed significant difference, which leads to the need for establishing standardized norms for various facial proportions in Indian population. PMID:28217534

  16. Ontogeny of modern human longitudinal body and transverse shoulder proportions.

    PubMed

    Frelat, Mélanie A; Coquerelle, Michael; Trinkaus, Erik

    2017-03-01

    Whereas variation of modern human adult body size and shape has been widely studied in the context of ecogeographical clines, little is known about the differential growth patterns of transverse and longitudinal dimensions among human populations. Our study explored the ontogenetic variation of those body proportions in modern humans. We compared results from four different approaches to study cross-sectional skeletal samples of Africans (n = 43), Amerindians (n = 69) and Europeans (n = 40) from 0 to 14 years of age. Clavicle, humerus, and femur intermetaphyseal lengths, and femoral distal metaphyseal breadth, were measured. Average ontogenetic trajectories were computed in order to compare the growth patterns of the three groups. Our findings demonstrated that the three geographical groups shared similar absolute and relative patterns of change with age for the four dimensions considered. Although interpopulation differences existed in transverse to longitudinal as well as in interlimb proportions, those differences did not seem to remain constant throughout ontogeny, similar to what has been shown for intralimb proportions. Growth rates of transverse shoulder proportions differed between populations from different regions after 10 years, whereas those for longitudinal proportions were very similar. The ontogeny of transverse shoulder proportions is more complex than what is observed for bi-iliac breadth, suggesting that transverse shoulder to limb proportions are not solely influenced by ecogeographical conditions. Our analysis demonstrates that methodologies that incorporate critical dimensions of body form could shed new light on human adaptation in both paleontological and neontological contexts. © 2016 Wiley Periodicals, Inc.

  17. Assessment of facial golden proportions among central Indian population.

    PubMed

    Saurabh, Rathore; Piyush, Bolya; Sourabh, Bhatt; Preeti, Ojha; Trivedi, Rutvik; Vishnoi, Pradeep

    2016-12-01

    This study aimed to identify and establish the facial and smile proportions in young adults and to compare the results with ideal or divine proportions, compare the proportions of males and females included in our study population and compare them with those established for Caucasian and Japanese populations. Two hundred participants (164 females, 36 males) with Angle's class I malocclusion (M.O). and well-balanced faces were selected and photographed in the frontal repose position. Analysis was done in Adobe Photoshop software. Statistical analysis was done using the Statistical Package for the Social Sciences version 17.0. (IBM Corporation Armonk, New York, United States). Results suggested that females are more near to ideal ratios and males are more deviated from the ideal ratios. The proportions of males and females were not considerably different from each other. In Indian population, upper 3(rd) facial height (TR-LC) was increased and mid-face height (LC-LN) was decreased; in lower 3(rd) of the face, LN-CH was slightly increased in comparison to CH-ME. In facial widths, outer canthal width (LC-LC) was greater in the Indian population and mouth width (CH-CH) was normal. When compared with Indian population, Japanese participants had wider noses, outer canthal distance, and bitemporal width. It was concluded that significant difference was found between the proportions of the Indian population and ideal ratio. When Indian population was compared with Japanese and Caucasian populations, some parameters of facial proportions showed significant difference, which leads to the need for establishing standardized norms for various facial proportions in Indian population.

  18. Limb-size proportions in Australopithecus afarensis and Australopithecus africanus.

    PubMed

    Green, David J; Gordon, Adam D; Richmond, Brian G

    2007-02-01

    Previous analyses have suggested that Australopithecus africanus possessed more apelike limb proportions than Australopithecus afarensis. However, due to the errors involved in estimating limb length and body size, support for this conclusion has been limited. In this study, we use a new Monte Carlo method to (1) test the hypothesis that A. africanus had greater upper:lower limb-size proportions than A. afarensis and (2) assess the statistical significance of interspecific differences among these taxa, extant apes, and humans. Our Monte Carlo method imposes sampling constraints that reduce extant ape and human postcranial measurements to sample sizes comparable to the fossil samples. Next, composite ratios of fore- and hindlimb geometric means are calculated for resampled measurements from the fossils and comparative taxa. Mean composite ratios are statistically indistinguishable (alpha=0.05) from the actual ratios of extant individuals, indicating that this method conserves each sample's central tendency. When applied to the fossil samples, upper:lower limb-size proportions in A. afarensis are similar to those of humans (p=0.878) and are significantly different from all great ape proportions (p< or =0.034), while Australopithecus africanus is more similar to the apes (p> or =0.180) and significantly different from humans and A. afarensis (p< or =0.031). These results strongly support the hypothesis that A. africanus possessed more apelike limb-size proportions than A. afarensis, suggesting that A. africanus either evolved from a more postcranially primitive ancestor than A. afarensis or that the more apelike limb-size proportions of A. africanus were secondarily derived from an A. afarensis-like ancestor. Among the extant taxa, limb-size proportions correspond with observed levels of forelimb- and hindlimb-dominated positional behaviors. In conjunction with detailed anatomical features linked to arboreality, these results suggest that arboreal posture and

  19. Measurement Techniques for Flow Diagnostic in ITAM Impulse Wind Tunnels

    DTIC Science & Technology

    2010-04-01

    induces an electromotive force of bridge disbalance, proportional to the pressure difference on the membrane, and corresponding current at the system...test series is within 5 %. Figure 14 shows a typical Interferogram obtained by measuring the heat fluxes on the windward surface of a delta wing with

  20. Collaboration promotes proportional reasoning about resource distribution in young children.

    PubMed

    Ng, Rowena; Heyman, Gail D; Barner, David

    2011-09-01

    The authors investigated how children and adults evaluate the "niceness" of individuals who engage in resource distribution, with a focus on their sensitivity to the proportion of resources given. Across 3 experiments, subjects evaluated the niceness of a child who gave a quantity of pennies to another child. In Study 1 (N = 30), adults showed sensitivity to the proportion given, whereas 5- and 7-year-old children did not. In Study 2 (N = 74), both younger (3- to 5-year-old) and older (6- to 8-year-old) children were sensitive to proportion only when resources were earned by a giver in collaboration with the recipient rather than by the giver alone. Adults, however, were sensitive to proportion in both cases. In Study 3 (N = 44), the authors tested 5- and 6-year-olds and their parents to be sure that socioeconomic and ethnic differences between samples did not drive results and replicated key findings from Studies 1 and 2. Together, these findings indicate that children favor proportional resource distribution in situations that invoke intuitions about equity. The authors suggest that these intuitions may form the basis for adult notions of fairness and generosity.

  1. Limb proportions show developmental plasticity in response to embryo movement

    PubMed Central

    Pollard, A. S.; Charlton, B. G.; Hutchinson, J. R.; Gustafsson, T.; McGonnell, I. M.; Timmons, J. A.; Pitsillides, A. A.

    2017-01-01

    Animals have evolved limb proportions adapted to different environments, but it is not yet clear to what extent these proportions are directly influenced by the environment during prenatal development. The developing skeleton experiences mechanical loading resulting from embryo movement. We tested the hypothesis that environmentally-induced changes in prenatal movement influence embryonic limb growth to alter proportions. We show that incubation temperature influences motility and limb bone growth in West African Dwarf crocodiles, producing altered limb proportions which may, influence post-hatching performance. Pharmacological immobilisation of embryonic chickens revealed that altered motility, independent of temperature, may underpin this growth regulation. Use of the chick also allowed us to merge histological, immunochemical and cell proliferation labelling studies to evaluate changes in growth plate organisation, and unbiased array profiling to identify specific cellular and transcriptional targets of embryo movement. This disclosed that movement alters limb proportions and regulates chondrocyte proliferation in only specific growth plates. This selective targeting is related to intrinsic mTOR (mechanistic target of rapamycin) pathway activity in individual growth plates. Our findings provide new insights into how environmental factors can be integrated to influence cellular activity in growing bones and ultimately gross limb morphology, to generate phenotypic variation during prenatal development. PMID:28165010

  2. How well proportioned are lens and prism spaces?

    NASA Astrophysics Data System (ADS)

    Aurich, R.; Lustig, S.

    2012-09-01

    The cosmic microwave background (CMB) anisotropies in spherical 3-spaces with a non-trivial topology are analysed with a focus on lens- and prism-shaped fundamental cells. The conjecture is tested that well-proportioned spaces lead to a suppression of large-scale anisotropies according to the observed CMB. The focus is put on lens spaces L(p, q) which are supposed to be oddly proportioned. However, there are inhomogeneous lens spaces whose shape of the Voronoi domain depends on the position of the observer within the manifold. Such manifolds possess no fixed measure of the well-proportioned property and allow a predestined test of the well-proportioned conjecture. Topologies having the same Voronoi domain are shown to possess distinct CMB statistics which thus provide a counter-example to the well-proportioned conjecture. The CMB properties are analysed in terms of cyclic subgroups Zp, and a new point of view for the superior behaviour of the Poincaré dodecahedron is found.

  3. Boron-Lined Multichamber and Conventional Neutron Proportional Counter Tests

    SciTech Connect

    Woodring, Mitchell L.; Ely, James H.; Kouzes, Richard T.; Stromswold, David C.

    2010-09-07

    Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. These technologies are: 1) Boron trifluoride (BF3)-filled proportional counters, 2) Boron-lined proportional counters, 3) Lithium-loaded glass fibers, and 4) Coated non-scintillating plastic fibers. In addition, a few other companies have detector technologies that might be competitive in the near term as an alternative technology. Reported here are the results of tests of a boron-lined, multichamber proportional counter manufactured by LND, Inc. Also reported are results obtained with an earlier design of conventional, boron-lined, proportional counters from LND. This testing measured the required performance for neutron detection efficiency and gamma-ray rejection capabilities of the detectors.

  4. Estimation of proportions in mixed pixels through their region characterization

    NASA Technical Reports Server (NTRS)

    Chittineni, C. B. (Principal Investigator)

    1981-01-01

    A region of mixed pixels can be characterized through the probability density function of proportions of classes in the pixels. Using information from the spectral vectors of a given set of pixels from the mixed pixel region, expressions are developed for obtaining the maximum likelihood estimates of the parameters of probability density functions of proportions. The proportions of classes in the mixed pixels can then be estimated. If the mixed pixels contain objects of two classes, the computation can be reduced by transforming the spectral vectors using a transformation matrix that simultaneously diagonalizes the covariance matrices of the two classes. If the proportions of the classes of a set of mixed pixels from the region are given, then expressions are developed for obtaining the estmates of the parameters of the probability density function of the proportions of mixed pixels. Development of these expressions is based on the criterion of the minimum sum of squares of errors. Experimental results from the processing of remotely sensed agricultural multispectral imagery data are presented.

  5. Limb proportions show developmental plasticity in response to embryo movement.

    PubMed

    Pollard, A S; Charlton, B G; Hutchinson, J R; Gustafsson, T; McGonnell, I M; Timmons, J A; Pitsillides, A A

    2017-02-06

    Animals have evolved limb proportions adapted to different environments, but it is not yet clear to what extent these proportions are directly influenced by the environment during prenatal development. The developing skeleton experiences mechanical loading resulting from embryo movement. We tested the hypothesis that environmentally-induced changes in prenatal movement influence embryonic limb growth to alter proportions. We show that incubation temperature influences motility and limb bone growth in West African Dwarf crocodiles, producing altered limb proportions which may, influence post-hatching performance. Pharmacological immobilisation of embryonic chickens revealed that altered motility, independent of temperature, may underpin this growth regulation. Use of the chick also allowed us to merge histological, immunochemical and cell proliferation labelling studies to evaluate changes in growth plate organisation, and unbiased array profiling to identify specific cellular and transcriptional targets of embryo movement. This disclosed that movement alters limb proportions and regulates chondrocyte proliferation in only specific growth plates. This selective targeting is related to intrinsic mTOR (mechanistic target of rapamycin) pathway activity in individual growth plates. Our findings provide new insights into how environmental factors can be integrated to influence cellular activity in growing bones and ultimately gross limb morphology, to generate phenotypic variation during prenatal development.

  6. Force-detecting gripper and force feedback system for neurosurgery applications.

    PubMed

    Yoneyama, Takeshi; Watanabe, Tetsuyou; Kagawa, Hiroyuki; Hamada, Junichiro; Hayashi, Yutaka; Nakada, Mitsutoshi

    2013-09-01

    For the application of less invasive robotic neurosurgery to the resection of deep-seated tumors, a prototype system of a force-detecting gripper with a flexible micromanipulator and force feedback to the operating unit will be developed. Gripping force applied on the gripper is detected by strain gauges attached to the gripper clip. The signal is transmitted to the amplifier by wires running through the inner tube of the manipulator. Proportional force is applied on the finger lever of the operating unit by the surgeon using a bilateral control program. A pulling force experienced by the gripper is also detected at the gripper clip. The signal for the pulling force is transmitted in a manner identical to that mentioned previously, and the proportional torque is applied on the touching roller of the finger lever of the operating unit. The surgeon can feel the gripping force as the resistance of the operating force of the finger and can feel the pulling force as the friction at the finger surface. A basic operation test showed that both the gripping force and pulling force were clearly detected in the gripping of soft material and that the operator could feel the gripping force and pulling force at the finger lever of the operating unit. A prototype of the force feedback in the microgripping manipulator system has been developed. The system will be useful for removing deep-seated brain tumors in future master-slave-type robotic neurosurgery.

  7. Estimating the Proportion of True Null Hypotheses for Multiple Comparisons

    PubMed Central

    Jiang, Hongmei; Doerge, R.W.

    2008-01-01

    Whole genome microarray investigations (e.g. differential expression, differential methylation, ChIP-Chip) provide opportunities to test millions of features in a genome. Traditional multiple comparison procedures such as familywise error rate (FWER) controlling procedures are too conservative. Although false discovery rate (FDR) procedures have been suggested as having greater power, the control itself is not exact and depends on the proportion of true null hypotheses. Because this proportion is unknown, it has to be accurately (small bias, small variance) estimated, preferably using a simple calculation that can be made accessible to the general scientific community. We propose an easy-to-implement method and make the R code available, for estimating the proportion of true null hypotheses. This estimate has relatively small bias and small variance as demonstrated by (simulated and real data) comparing it with four existing procedures. Although presented here in the context of microarrays, this estimate is applicable for many multiple comparison situations. PMID:19259400

  8. Proportional ethical review and the identification of ethical issues

    PubMed Central

    Hunter, D

    2007-01-01

    Presently, there is a movement in the UK research governance framework towards what is referred to as proportional ethical review. Proportional ethical review is the notion that the level of ethical review and scrutiny given to a research project ought to reflect the level of ethical risk represented by that project. Relatively innocuous research should receive relatively minimal review and relatively risky research should receive intense scrutiny. Although conceptually attractive, the notion of proportional review depends on the possibility of effectively identifying the risks and ethical issues posed by an application with some process other than a full review by a properly constituted research ethics committee. In this paper, it is argued that this cannot be achieved and that the only appropriate means of identifying risks and ethical issues is consideration by a full committee. This implies that the suggested changes to the National Health Service research ethics system presently being consulted on should be strenuously resisted. PMID:17400625

  9. Wing spar stress charts and wing truss proportions

    NASA Technical Reports Server (NTRS)

    Warner, Edward P

    1926-01-01

    In order to simplify the calculation of beams continuous over three supports, a series of charts have been calculated giving the bending moments at all the critical points and the reactions at all supports for such members. Using these charts as a basis, calculations of equivalent bending moments, representing the total stresses acting in two bay-wing trusses of proportions varying over a wide range, have been determined, both with and without allowance for column effect. This leads finally to the determination of the best proportions for any particular truss or the best strut locations in any particular airplane. The ideal proportions are found to vary with the thickness of the wing section used, the aspect ratio, and the ratio of gap to chord.

  10. Safety studies on hydraulic proportional valves with electrical position feedback.

    PubMed

    Reinert, Dietmar; Kimura, Tetsuya; Gorgs, Karl-Josef

    2006-01-01

    The authors analysed a proportional valve with electrical position feedback for its failure behaviour. Several failures were introduced into the feedback loop, especially into the 2 solenoids and the inductive position transducer. The behaviour of the valve for square and ramp reference signals was recorded and systematically analysed. It was shown that failures could be detected by monitoring the residual signal from the equipment under control or the residual signal from the sensor. It was possible to achieve the safe position within twice the normal response time of the valve by switching off the current of both solenoids. The application of these results for a new generation of safe proportional valves is discussed. The use of the results of these investigations obviates the need for redundancy of the electrical position monitoring arrangement in a safe proportional valve.

  11. Estimating Regression Parameters in an Extended Proportional Odds Model

    PubMed Central

    Chen, Ying Qing; Hu, Nan; Cheng, Su-Chun; Musoke, Philippa; Zhao, Lue Ping

    2012-01-01

    The proportional odds model may serve as a useful alternative to the Cox proportional hazards model to study association between covariates and their survival functions in medical studies. In this article, we study an extended proportional odds model that incorporates the so-called “external” time-varying covariates. In the extended model, regression parameters have a direct interpretation of comparing survival functions, without specifying the baseline survival odds function. Semiparametric and maximum likelihood estimation procedures are proposed to estimate the extended model. Our methods are demonstrated by Monte-Carlo simulations, and applied to a landmark randomized clinical trial of a short course Nevirapine (NVP) for mother-to-child transmission (MTCT) of human immunodeficiency virus type-1 (HIV-1). Additional application includes analysis of the well-known Veterans Administration (VA) Lung Cancer Trial. PMID:22904583

  12. Influences of limb proportions and body size on locomotor kinematics in terrestrial primates and fossil hominins.

    PubMed

    Polk, J D

    2004-10-01

    During locomotion, mammalian limb postures are influenced by many factors including the animal's limb length and body mass. Polk (2002) compared the gait of similar-sized cercopithecine monkeys that differed limb proportions and found that longer-limbed monkeys usually adopt more extended joint postures than shorter-limbed monkeys in order to moderate their joint moments. Studies of primates as well as non-primate mammals that vary in body mass have demonstrated that larger animals use more extended limb postures than smaller animals. Such extended postures in larger animals increase the extensor muscle mechanical advantage and allow postures to be maintained with relatively less muscular effort (Polk, 2002; Biewener 1989). The results of these previous studies are used here to address two anthropological questions. The first concerns the postural effects of body mass and limb proportion differences between australopithecines and members of the genus Homo. That is, H. erectus and later hominins all have larger body mass and longer legs than australopithecines, and these anatomical differences suggest that Homo probably used more extended postures and probably required relatively less muscular force to resist gravity than the smaller and shorter-limbed australopithecines. The second question investigates how animals with similar size but different limb proportions differ in locomotor performance. The effects of limb proportions on gait are relevant to inferring postural and locomotor differences between Neanderthals and modern Homo sapiens which differ in their crural indices and relative limb length. This study demonstrates that primates with relatively long limbs achieve higher walking speeds while using lower stride frequencies and lower angular excursions than shorter-limbed monkeys, and these kinematic differences may allow longer-limbed taxa to locomote more efficiently than shorter-limbed species of similar mass. Such differences may also have characterized

  13. Leg Length, Body Proportion, and Health: A Review with a Note on Beauty

    PubMed Central

    Bogin, Barry; Varela-Silva, Maria Inês

    2010-01-01

    Decomposing stature into its major components is proving to be a useful strategy to assess the antecedents of disease, morbidity and death in adulthood. Human leg length (femur + tibia), sitting height (trunk length + head length) and their proportions, for example, (leg length/stature), or the sitting height ratio (sitting height/stature × 100), among others) are associated with epidemiological risk for overweight (fatness), coronary heart disease, diabetes, liver dysfunction and certain cancers. There is also wide support for the use of relative leg length as an indicator of the quality of the environment for growth during infancy, childhood and the juvenile years of development. Human beings follow a cephalo-caudal gradient of growth, the pattern of growth common to all mammals. A special feature of the human pattern is that between birth and puberty the legs grow relatively faster than other post-cranial body segments. For groups of children and youth, short stature due to relatively short legs (i.e., a high sitting height ratio) is generally a marker of an adverse environment. The development of human body proportions is the product of environmental x genomic interactions, although few if any specific genes are known. The HOXd and the short stature homeobox-containing gene (SHOX) are genomic regions that may be relevant to human body proportions. For example, one of the SHOX related disorders is Turner syndrome. However, research with non-pathological populations indicates that the environment is a more powerful force influencing leg length and body proportions than genes. Leg length and proportion are important in the perception of human beauty, which is often considered a sign of health and fertility. PMID:20617018

  14. Morphology and motion: hindlimb proportions and swing phase kinematics in terrestrially locomoting charadriiform birds.

    PubMed

    Kilbourne, Brandon M; Andrada, Emanuel; Fischer, Martin S; Nyakatura, John A

    2016-05-01

    Differing limb proportions in terms of length and mass, as well as differences in mass being concentrated proximally or distally, influence the limb's moment of inertia (MOI), which represents its resistance to being swung. Limb morphology - including limb segment proportions - thus probably has direct relevance for the metabolic cost of swinging the limb during locomotion. However, it remains largely unexplored how differences in limb proportions influence limb kinematics during swing phase. To test whether differences in limb proportions are associated with differences in swing phase kinematics, we collected hindlimb kinematic data from three species of charadriiform birds differing widely in their hindlimb proportions: lapwings, oystercatchers and avocets. Using these three species, we tested for differences in maximum joint flexion, maximum joint extension and range of motion (RoM), in addition to differences in maximum segment angular velocity and excursion. We found that the taxa with greater limb MOI - oystercatchers and avocets - flex their limbs more than lapwings. However, we found no consistent differences in joint extension and RoM among species. Likewise, we found no consistent differences in limb segment angular velocity and excursion, indicating that differences in limb inertia in these three avian species do not necessarily underlie the rate or extent of limb segment movements. The observed increased limb flexion among these taxa with distally heavy limbs resulted in reduced MOI of the limb when compared with a neutral pose. A trade-off between exerting force to actively flex the limb and potential savings by a reduction of MOI is skewed towards reducing the limb's MOI as a result of MOI being in part a function of the radius of gyration squared. Increased limb flexion is a likely means to lower the cost of swinging the limbs. © 2016. Published by The Company of Biologists Ltd.

  15. Leg length, body proportion, and health: a review with a note on beauty.

    PubMed

    Bogin, Barry; Varela-Silva, Maria Inês

    2010-03-01

    Decomposing stature into its major components is proving to be a useful strategy to assess the antecedents of disease, morbidity and death in adulthood. Human leg length (femur + tibia), sitting height (trunk length + head length) and their proportions, for example, (leg length/stature), or the sitting height ratio (sitting height/stature x 100), among others) are associated with epidemiological risk for overweight (fatness), coronary heart disease, diabetes, liver dysfunction and certain cancers. There is also wide support for the use of relative leg length as an indicator of the quality of the environment for growth during infancy, childhood and the juvenile years of development. Human beings follow a cephalo-caudal gradient of growth, the pattern of growth common to all mammals. A special feature of the human pattern is that between birth and puberty the legs grow relatively faster than other post-cranial body segments. For groups of children and youth, short stature due to relatively short legs (i.e., a high sitting height ratio) is generally a marker of an adverse environment. The development of human body proportions is the product of environmental x genomic interactions, although few if any specific genes are known. The HOXd and the short stature homeobox-containing gene (SHOX) are genomic regions that may be relevant to human body proportions. For example, one of the SHOX related disorders is Turner syndrome. However, research with non-pathological populations indicates that the environment is a more powerful force influencing leg length and body proportions than genes. Leg length and proportion are important in the perception of human beauty, which is often considered a sign of health and fertility.

  16. Proportional Motor Recovery After Stroke: Implications for Trial Design.

    PubMed

    Stinear, Cathy M; Byblow, Winston D; Ackerley, Suzanne J; Smith, Marie-Claire; Borges, Victor M; Barber, P Alan

    2017-03-01

    Recovery of upper-limb motor impairment after first-ever ischemic stroke is proportional to the degree of initial impairment in patients with a functional corticospinal tract (CST). This study aimed to investigate whether proportional recovery occurs in a more clinically relevant sample including patients with intracerebral hemorrhage and previous stroke. Patients with upper-limb weakness were assessed 3 days and 3 months poststroke with the Fugl-Meyer scale. Transcranial magnetic stimulation was used to test CST function, and patients were dichotomized according to the presence of motor evoked potentials in the paretic wrist extensors. Linear regression modeling of Δ Fugl-Meyer score between 3 days and 3 months was performed, with predictors including initial impairment (66 - baseline Fugl-Meyer score), age, sex, stroke type, previous stroke, comorbidities, and upper-limb therapy dose. One hundred ninety-two patients were recruited, and 157 completed 3-month follow-up. Patients with a functional CST made a proportional recovery of 63% (95% confidence interval, 55%-70%) of initial motor impairment. The recovery of patients without a functional CST was not proportional to initial impairment and was reduced by greater CST damage. Recovery of motor impairment in patients with intact CST is proportional to initial impairment and unaffected by previous stroke, type of stroke, or upper-limb therapy dose. Novel interventions that interact with the neurobiological mechanisms of recovery are needed. The generalizability of proportional recovery is such that patients with intracerebral hemorrhage and previous stroke may usefully be included in interventional rehabilitation trials. URL: http://www.anzctr.org.au. Unique identifier: ANZCTR12611000755932. © 2017 American Heart Association, Inc.

  17. Evaluation of Bayesian Sequential Proportion Estimation Using Analyst Labels

    NASA Technical Reports Server (NTRS)

    Lennington, R. K.; Abotteen, K. M. (Principal Investigator)

    1980-01-01

    The author has identified the following significant results. A total of ten Large Area Crop Inventory Experiment Phase 3 blind sites and analyst-interpreter labels were used in a study to compare proportional estimates obtained by the Bayes sequential procedure with estimates obtained from simple random sampling and from Procedure 1. The analyst error rate using the Bayes technique was shown to be no greater than that for the simple random sampling. Also, the segment proportion estimates produced using this technique had smaller bias and mean squared errors than the estimates produced using either simple random sampling or Procedure 1.

  18. Gas scintillation proportional counters for x-ray synchrotron applications

    SciTech Connect

    Smith, A. ); Bavdaz, M. )

    1992-01-01

    Gas scintillation proportional counters (GSPCs) as x-ray detectors provide some advantages and disadvantages compared with proportional counters. In this paper the various configurations of xenon filled GSPC are described including both imaging and nonimaging devices. It is intended that this work be used to configure a GSPC for a particular application and predict its general performance characteristics. The general principles of operation are described and the performance characteristics are then separately considered. A high performance, imaging, driftless GSPC is described in which a single intermediate window is used between the PMT and gas cell.

  19. Forced Snaking

    NASA Astrophysics Data System (ADS)

    Ponedel, Benjamin; Knobloch, Edgar

    2016-11-01

    We study spatial localization in the real subcritical Ginzburg-Landau equation ut =m0 u +m1 cos2/π l x u +uxx +d | u | 2 u -| u | 4 u with spatially periodic forcing. When d > 0 and m1 = 0 this equation exhibits bistability between the trivial state u = 0 and a homogeneous nontrivial state u =u0 with stationary localized structures which accumulate at the Maxwell point m0 = - 3d2 / 16 . When spatial forcing is included its wavelength is imprinted on u0 creating conditions favorable to front pinning and hence spatial localization. We use numerical continuation to show that under appropriate conditions such forcing generates a sequence of localized states organized within a snakes-and-ladders structure centered on the Maxwell point, and refer to this phenomenon as forced snaking. We determine the stability properties of these states and show that longer lengthscale forcing leads to stationary trains consisting of a finite number of strongly localized, weakly interacting pulses exhibiting foliated snaking.

  20. Measuring the Drag Force on a Falling Ball

    ERIC Educational Resources Information Center

    Cross, Rod; Lindsey, Crawford

    2014-01-01

    The effect of the aerodynamic drag force on an object in flight is well known and has been described in this and other journals many times. At speeds less than about 1 m/s, the drag force on a sphere is proportional to the speed and is given by Stokes' law. At higher speeds, the drag force is proportional to the velocity squared and is…

  1. Measuring the Drag Force on a Falling Ball

    ERIC Educational Resources Information Center

    Cross, Rod; Lindsey, Crawford

    2014-01-01

    The effect of the aerodynamic drag force on an object in flight is well known and has been described in this and other journals many times. At speeds less than about 1 m/s, the drag force on a sphere is proportional to the speed and is given by Stokes' law. At higher speeds, the drag force is proportional to the velocity squared and is…

  2. Force approach to radiation reaction

    NASA Astrophysics Data System (ADS)

    López, Gustavo V.

    2016-02-01

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  3. Force approach to radiation reaction

    SciTech Connect

    López, Gustavo V.

    2016-02-15

    The difficulty of the usual approach to deal with the radiation reaction is pointed out, and under the condition that the radiation force must be a function of the external force and is zero whenever the external force be zero, a new and straightforward approach to radiation reaction force and damping is proposed. Starting from the Larmor formula for the power radiated by an accelerated charged particle, written in terms of the applied force instead of the acceleration, an expression for the radiation force is established in general, and applied to the examples for the linear and circular motion of a charged particle. This expression is quadratic in the magnitude of the applied force, inversely proportional to the speed of the charged particle, and directed opposite to the velocity vector. This force approach may contribute to the solution of the very old problem of incorporating the radiation reaction to the motion of the charged particles, and future experiments may tell us whether or not this approach point is in the right direction.

  4. Behavior of Boundary Layer in Supersonic Flow with Applied Lorentz Force

    NASA Astrophysics Data System (ADS)

    Udagawa, Keisuke; Saito, Shinya; Kawaguchi, Kenji; Tomioka, Sadatake; Yamasaki, Hiroyuki

    Experimental study on behavior of boundary layer in supersonic flow with applied Lorentz force was carried out. In the experiment, Mach 1.5 supersonic wind tunnel driven by a shock-tube was used. At the test section, the current from the external DC power supply and the magnetic field of 2.4 Tesla were applied to the boundary layer developing on the bottom wall. Argon seeded with cesium was used as an electrically conducting gas. Effect of the direction of the Lorentz force on static pressure distribution was investigated, and the remarkable increase of static pressure at the test section was observed for the decelerating Lorentz force. It is noted that the acceleration of the flow inside the boundary layer was demonstrated for the first time without accelerating the main flow when the accelerating Lorentz force was applied. At the same time, the acceleration efficiency defined by a ratio of work done by the Lorentz force to energy input into the flow was found 54-61%. These results have suggested the possibility of the boundary layer separation control by applying the accelerating Lorentz force. In the case of the decelerating Lorentz force, the significant reduction of Mach number was observed not only inside the boundary layer but also in the main flow. The reduction of Mach number could be ascribed to the growth of the boundary layer due to gas heating inside the boundary layer. When the direction of the current was changed, the difference of light emission from the discharge inside the boundary layer was observed, and this was due to the difference of the electromotive force induced in the supersonic flow.

  5. Intermolecular forces.

    PubMed

    Buckingham, A D

    1975-11-06

    The nature of molecular interactions is examined. Intermolecular forces are divided into long-range and short-range components; the former operate at distances where the effects of electron exchange are negligible and decrease as an inverse power of the separation. The long-range interactions may be subdividied into electrostatic, induction and dispersion contributions, where the electrostatic component is the interaction of the permanent charge distributions and the others originate in the fluctuations in the distributions. Typical magnitudes of the various contributions are given. The forces between macroscopic bodies are briefly considered, as are the effects of a medium. Some of the manifestations of molecular interactions are discussed.

  6. Image Force Microscopy

    NASA Astrophysics Data System (ADS)

    Rajapaksa, Indrajith

    In this thesis we describe an enhancement to the Atomic force microscope (AFM) to simultaneously gather topographic features and spectroscopic information .Compared to the current state of the art of near-field excitation and far-field detection AFM imaging techniques our system uses a radical new approach near-field excitation and near-field detection. By placing the detector in the near-field we achieve high signal to noise and single molecular resolution. The origin of our near-field detector signal is the image force gradient due to the interaction of the stimulated molecular dipole with its image on the metal probe. We designed and built an optical and electronic system to capture this signal and simultaneously image nano-scale surface topography and optical image force gradient. By varying the wavelength of the excitation beam we measure the induced optical image force gradient spectra of molecules on surface. These spectra show good agreement with the absorption spectra of the bulk molecules measured by conventional absorption spectroscopy. We show that image force gradient is directly proportional to the optical absorption dipole strength. Using Finite Element 3D electromagnetic simulations and using Lorentz model for the excited molecular dipole we showed that the image force gradient has a decay length of 1nm, making the theoretical resolution of this microscopy technique approximately 1 nm. This rapid decay was measured experimentally .This resolution was seen by the high contrasting spectroscopic images of molecules on the surface. In follow on experiments this technique was extended to provide surface Raman spectroscopy and microscopy at molecular resolution. We create an image force gradient interaction through optical parametric down conversion between stimulated Raman excited molecules on a surface and a cantilevered nanometer scale probe brought very close to it. Spectroscopy and microscopy on clusters of molecules have been performed. Single

  7. From Graphical to Mathematical: The Spiral of Golden Proportion

    ERIC Educational Resources Information Center

    Fletcher, Rodney

    2007-01-01

    There has been a lot of material written about logarithmic spirals of golden proportion but this author states that he has never come across an article that states the exact equation of the spiral which ultimately spirals tangentially to the sides of the rectangles. In this article, the author intends to develop such an equation. (Contains 5…

  8. Are Explicit Apologies Proportional to the Offenses They Address?

    ERIC Educational Resources Information Center

    Heritage, John; Raymond, Chase Wesley

    2016-01-01

    We consider here Goffman's proposal of proportionality between virtual offenses and remedial actions, based on the examination of 102 cases of explicit apologies. To this end, we offer a typology of the primary apology formats within the dataset, together with a broad categorization of the types of virtual offenses to which these apologies are…

  9. Modelling boron-lined proportional counter response to neutrons.

    PubMed

    Shahri, A; Ghal-Eh, N; Etaati, G R

    2013-09-01

    The detailed Monte Carlo simulation of a boron-lined proportional counter response to a neutron source has been presented. The MCNP4C and experimental data on different source-moderator geometries have been given for comparison. The influence of different irradiation geometries and boron-lining thicknesses on the detector response has been studied.

  10. Proportional Reasoning in the Learning of Chemistry: Levels of Complexity

    ERIC Educational Resources Information Center

    Ramful, Ajay; Narod, Fawzia Bibi

    2014-01-01

    This interdisciplinary study sketches the ways in which proportional reasoning is involved in the solution of chemistry problems, more specifically, problems involving quantities in chemical reactions (commonly referred to as stoichiometry problems). By building on the expertise of both mathematics and chemistry education research, the present…

  11. An Investigation of Proportional Reasoning Skills of Middle School Students

    ERIC Educational Resources Information Center

    Ozgun-Koca, S. Asli; Altay, Mesture Kayhan

    2009-01-01

    The purpose of this study was to examine the proportional reasoning skills of Turkish middle school students. It was also aimed at revealing the differences in students' performances in terms of their gender, grade level, and problem types--missing value and numerical comparison. The study was conducted with two sixth and seventh grade classes…

  12. The Structure of Prospective Kindergarten Teachers' Proportional Reasoning

    ERIC Educational Resources Information Center

    Pitta-Pantazi, Demetra; Christou, Constantinos

    2011-01-01

    Lamon ("Teaching fractions and ratios for understanding. Essential content knowledge and instructional strategies for teachers," 2nd edn. Lawrence Erlbaum Associates, Mahwah, 2005) claimed that the development of proportional reasoning relies on various kinds of understanding and thinking processes. The critical components suggested were…

  13. Are Explicit Apologies Proportional to the Offenses They Address?

    ERIC Educational Resources Information Center

    Heritage, John; Raymond, Chase Wesley

    2016-01-01

    We consider here Goffman's proposal of proportionality between virtual offenses and remedial actions, based on the examination of 102 cases of explicit apologies. To this end, we offer a typology of the primary apology formats within the dataset, together with a broad categorization of the types of virtual offenses to which these apologies are…

  14. The aesthetic proportion index of facial contour surgery.

    PubMed

    Li, Dong; Xu, Haisong; Xu, Liang; Huang, Xiaoxiang; Yuan, Jie; Wei, Min

    2015-03-01

    An oval-shaped face is considered ideal in Chinese culture, which means not only narrow mid and low face but also appropriate proportion between them. Numerous surgical resections of the malar and mandibular angles began in the 1980s. The objective of this study was to investigate the facial proportion index before and after facial contour surgery. All 266 patients were subjected to L-shaped reduction malarplasty and reduction of mandibular angles with partial masseter muscle resection. All computed tomographic parameters (preoperative and 2 years postoperative) were conducted on facial morphometry to reveal the change of the facial proportion index of hard and soft tissue, respectively, such as the widest part of the mid face (WM), widest part of the lower face (WL), facial height (FH), WM/WL, WM/FH, and WL/FH. All patients were satisfied with the optimal outcome of the combined facial contour surgery. Morphometric analysis indicated that the ideal WM/WL ratio was 1.27 ± 0.1 (1.21 ± 0.09 preoperative) in hard tissue and 1.2 ± 0.12 (1.16 ± 0.12 preoperative) in soft tissue 2 years postoperatively. The combined facial contour surgery could acquire an ideal facial contour for Chinese patients. Furthermore, the relative proportion index can be referenced as the standard for preoperative design.

  15. Attentional Control and the Relatedness Proportion Effect in Semantic Priming

    ERIC Educational Resources Information Center

    Hutchison, Keith A.

    2007-01-01

    In 2 experiments, participants completed both an attentional control battery (OSPAN, antisaccade, and Stroop tasks) and a modified semantic priming task. The priming task measured relatedness proportion (RP) effects within subjects, with the color of the prime indicating the probability that the to-be-named target would be related. In Experiment…

  16. Proportional Reasoning in the Learning of Chemistry: Levels of Complexity

    ERIC Educational Resources Information Center

    Ramful, Ajay; Narod, Fawzia Bibi

    2014-01-01

    This interdisciplinary study sketches the ways in which proportional reasoning is involved in the solution of chemistry problems, more specifically, problems involving quantities in chemical reactions (commonly referred to as stoichiometry problems). By building on the expertise of both mathematics and chemistry education research, the present…

  17. The relation between spatial thinking and proportional reasoning in preschoolers.

    PubMed

    Möhring, Wenke; Newcombe, Nora S; Frick, Andrea

    2015-04-01

    Previous research has indicated a close link between spatial and mathematical thinking. However, what shared processes account for this link? In this study, we focused on the spatial skill of map reading and the mathematical skill of proportional reasoning and investigated whether scaling, or the ability to relate information in different-sized representations, is a shared process. Scaling was experimentally manipulated in both tasks. In the map task, 4- and 5-year-olds (N=50) were asked to point to the same position shown on a map in a larger referent space on a touch screen. The sizes of the maps were varied systematically, such that some trials required scaling and some did not (i.e., the map had the same size as the referent space). In the proportional reasoning task, children were presented with different relative amounts of juice and water and were asked to estimate each mixture on a rating scale. Again, some trials required scaling, but others could be solved by directly mapping the proportional components onto the rating scale. Children's absolute errors in locating targets in the map task were closely related to their performance in the proportional reasoning task even after controlling for age and verbal intelligence. Crucially, this was only true for trials that required scaling, whereas performance on nonscaled trials was not related. These results shed light on the mechanisms involved in the close connection between spatial and mathematical thinking early in life.

  18. Spatio-temporal patterns of proportions of influenza B cases

    PubMed Central

    He, Daihai; Chiu, Alice P. Y.; Lin, Qianying; Yu, Duo

    2017-01-01

    We studied the spatio-temporal patterns of the proportions of influenza B cases out of all typed cases, with data from 139 countries and regions downloaded from the FluNet compiled by the World Health Organization, from January 2006 to October 2015. We restricted our analysis to 34 countries that reported more than 2,000 confirmations for each of types A and B over the study period. Globally, we found that Pearson’s correlation is greater than 0.6 between effective distance from Mexico and the proportions of influenza B cases among the countries during the post-pandemic era (i.e. Week 1, 2010 to Week 40, 2015). Locally, in the United States, the proportions of influenza B cases in the pre-pandemic period (2003–2008) negatively correlated with that in the post-pandemic era (2010–2015) at the regional level. Our study limitations are the country-level variations in both surveillance methods and testing policies. The proportions of influenza B cases displayed wide variations over the study period. Our findings suggest that the 2009 influenza pandemic has an evident impact on the relative burden of the two influenza types. Future studies should examine whether there are other additional factors. This study has potential implications in prioritizing public health control measures. PMID:28067277

  19. Making Sense of Fractions, Ratios, and Proportions. 2002 Yearbook.

    ERIC Educational Resources Information Center

    Litwiller, Bonnie, Ed.; Bright, George, Ed.

    This yearbook contains articles that give insight into students' thinking about factions, ratios, and proportions. Suggestions are offered on how to develop the concepts and skills associated with these topics. The book is divided into elementary, middle school, and professional development sections. Chapters include: (1) "The Development of…

  20. Map Scale, Proportion, and Google[TM] Earth

    ERIC Educational Resources Information Center

    Roberge, Martin C.; Cooper, Linda L.

    2010-01-01

    Aerial imagery has a great capacity to engage and maintain student interest while providing a contextual setting to strengthen their ability to reason proportionally. Free, on-demand, high-resolution, large-scale aerial photography provides both a bird's eye view of the world and a new perspective on one's own community. This article presents an…

  1. Development of proportional counters using photosensitive gases and liquids

    SciTech Connect

    Anderson, D.F.

    1984-10-01

    An introduction to the history and to the principle of operation of wire chambers using photosensitive gases and liquids is presented. Their use as light sensors coupled to Gas Scintillation Proportional Counters and BaF/sub 2/, as well as their use in Cherenkov Ring imaging, is discussed in some detail. 42 references, 21 figures.

  2. Macroevolutionary diversity of amniote limb proportions predicted by developmental interactions.

    PubMed

    Young, Nathan M

    2013-11-01

    Mammals, birds, and reptiles exhibit a remarkable diversity of limb proportions. These evolved differences are thought to reflect selection for biomechanical, postural, and locomotor requirements primarily acting on independent variation in later fetal and postnatal segmental growth. However, earlier conserved developmental events also have the potential to impact the evolvability of limb proportions by limiting or biasing initial variation among segments. Notably, proximo-distal patterning of the amniote limb through activation-inhibition dynamics predicts that initial proportions of segments should exhibit both tradeoffs between stylopod and autopod and a diagnostic reduction in variance of the zeugopod. Here it is demonstrated that this developmental "design rule" predicts patterns of macroevolutionary diversity despite the effects of variation in segmental growth over ontogeny, lineage-specific differences in phylogenetic history, or functional adaptation. These results provide critical comparative evidence of a conserved Turing-like mechanism in proximo-distal limb segmentation, and suggest that development has played a previously unrecognized role in the evolvability of limb proportions in a wide range of amniote taxa. © 2013 Wiley Periodicals, Inc.

  3. Spatio-temporal patterns of proportions of influenza B cases.

    PubMed

    He, Daihai; Chiu, Alice P Y; Lin, Qianying; Yu, Duo

    2017-01-09

    We studied the spatio-temporal patterns of the proportions of influenza B cases out of all typed cases, with data from 139 countries and regions downloaded from the FluNet compiled by the World Health Organization, from January 2006 to October 2015. We restricted our analysis to 34 countries that reported more than 2,000 confirmations for each of types A and B over the study period. Globally, we found that Pearson's correlation is greater than 0.6 between effective distance from Mexico and the proportions of influenza B cases among the countries during the post-pandemic era (i.e. Week 1, 2010 to Week 40, 2015). Locally, in the United States, the proportions of influenza B cases in the pre-pandemic period (2003-2008) negatively correlated with that in the post-pandemic era (2010-2015) at the regional level. Our study limitations are the country-level variations in both surveillance methods and testing policies. The proportions of influenza B cases displayed wide variations over the study period. Our findings suggest that the 2009 influenza pandemic has an evident impact on the relative burden of the two influenza types. Future studies should examine whether there are other additional factors. This study has potential implications in prioritizing public health control measures.

  4. Boron-Lined Multitube Neutron Proportional Counter Test

    SciTech Connect

    Woodring, Mitchell L.; Ely, James H.; Kouzes, Richard T.; Stromswold, David C.

    2010-09-07

    Radiation portal monitors used for interdiction of illicit materials at borders include highly sensitive neutron detection systems. The main reason for having neutron detection capability is to detect fission neutrons from plutonium. The currently deployed radiation portal monitors (RPMs) from Ludlum and Science Applications International Corporation (SAIC) use neutron detectors based upon 3He-filled gas proportional counters, which are the most common large neutron detector. There is a declining supply of 3He in the world, and thus, methods to reduce the use of this gas in RPMs with minimal changes to the current system designs and sensitivity to cargo-borne neutrons are being investigated. Four technologies have been identified as being currently commercially available, potential alternative neutron detectors to replace the use of 3He in RPMs. These technologies are: 1) Boron trifluoride (BF3)-filled proportional counters, 2) Boron-lined proportional counters, 3) Lithium-loaded glass fibers, and 4) Coated non-scintillating plastic fibers. In addition, a few other companies have detector technologies that might be competitive in the near term as an alternative technology. Reported here are the results of tests of a boron-lined, “multitube” proportional counter manufactured by Centronic Ltd. (Surry, U.K. and Houston, TX). This testing measured the required performance for neutron detection efficiency and gamma-ray rejection capabilities of the detector.

  5. Simulation of dynamics of hydraulic system with proportional control valve

    NASA Astrophysics Data System (ADS)

    Bureček, Adam; Hružík, Lumír; Vašina, Martin

    2016-03-01

    Dynamics of a hydraulic system is influenced by several parameters, in this case mainly by proportional control valve, oil bulk modulus, oil viscosity, mass load etc. This paper will be focused on experimental measurement and mathematical simulation of dynamics of a hydraulic system with proportional control valve, linear hydraulic cylinder and mass load. The measurement is performed on experimental equipment that enables realization of dynamic processes of the hydraulic system. Linear hydraulic cylinder with mass load is equipped with position sensor of piston. The movement control of piston rod is ensured by the proportional control valve. The equipment enables to test an influence of parameter settings of regulator of the proportional control valve on position and pressure system responses. The piston position is recorded by magnetostrictive sensor that is located in drilled piston rod side of the linear hydraulic cylinder. Pressures are measured by piezoresistive sensors on the piston side and the piston rod side of the hydraulic cylinder. The measurement is performed during movement of the piston rod with mass load to the required position. There is realized and verified a mathematical model using Matlab SimHydraulics software for this hydraulic system.

  6. [Regression models for variables expressed as a continuous proportion].

    PubMed

    Salinas-Rodríguez, Aarón; Pérez-Núñez, Ricardo; Avila-Burgos, Leticia

    2006-01-01

    To describe some of the statistical alternatives available for studying continuous proportions and to compare them in order to show their advantages and disadvantages by means of their application in a practical example of the Public Health field. From the National Reproductive Health Survey performed in 2003, the proportion of individual coverage in the family planning program--proposed in one study carried out in the National Institute of Public Health in Cuernavaca, Morelos, Mexico (2005)--was modeled using the Normal, Gamma, Beta and quasi-likelihood regression models. The Akaike Information Criterion (AIC) proposed by McQuarrie and Tsai was used to define the best model.Then, using a simulation (Monte Carlo/Markov Chains approach) a variable with a Beta distribution was generated to evaluate the behavior of the 4 models while varying the sample size from 100 to 18,000 observations. Results showed that the best statistical option for the analysis of continuous proportions was the Beta regression model, since its assumptions are easily accomplished and because it had the lowest AIC value. Simulation evidenced that while the sample size increases the Gamma, and even more so the quasi-likelihood, models come significantly close to the Beta regression model. The use of parametric Beta regression is highly recommended to model continuous proportions and the normal model should be avoided. If the sample size is large enough,the use of quasi-likelihood model represents a good alternative.

  7. Recommended tests and confidence intervals for paired binomial proportions.

    PubMed

    Fagerland, Morten W; Lydersen, Stian; Laake, Petter

    2014-07-20

    We describe, evaluate, and recommend statistical methods for the analysis of paired binomial proportions. A total of 24 methods are considered. The best tests for association include the asymptotic McNemar test and the McNemar mid- p test. For the difference between proportions, we recommend two simple confidence intervals with closed-form expressions and the asymptotic score interval. The asymptotic score interval is also recommended for the ratio of proportions, as is an interval with closed-form expression based on combining two Wilson score intervals for the single proportion. For the odds ratio, we recommend a transformation of the Wilson score interval and a transformation of the Clopper-Pearson mid- p interval. We illustrate the practical application of the methods using data from a recently published study of airway reactivity in children before and after stem cell transplantation and a matched case-control study of the association between floppy eyelid syndrome and obstructive sleep apnea-hypopnea syndrome.

  8. A Refined Item Digraph Analysis of a Proportional Reasoning Test.

    ERIC Educational Resources Information Center

    Bart, William M.; Williams-Morris, Ruth

    1990-01-01

    Refined item digraph analysis (RIDA) is a way of studying diagnostic and prescriptive testing. It permits assessment of a test item's diagnostic value by examining the extent to which the item has properties of ideal items. RIDA is illustrated with the Orange Juice Test, which assesses the proportionality concept. (TJH)

  9. System proportions fluid-flow in response to demand signals

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Control system provides proportioned fluid flow rates in response to demand signals. It compares a digital signal, representing a flow demand, with a reference signal to yield a control voltage to one or more solenoid valves connected to orifices of a predetermined size.

  10. The Structure of Prospective Kindergarten Teachers' Proportional Reasoning

    ERIC Educational Resources Information Center

    Pitta-Pantazi, Demetra; Christou, Constantinos

    2011-01-01

    Lamon ("Teaching fractions and ratios for understanding. Essential content knowledge and instructional strategies for teachers," 2nd edn. Lawrence Erlbaum Associates, Mahwah, 2005) claimed that the development of proportional reasoning relies on various kinds of understanding and thinking processes. The critical components suggested were…

  11. Prospective Elementary Teachers' Misunderstandings in Solving Ratio and Proportion Problems

    ERIC Educational Resources Information Center

    Monteiro, Cecilia

    2003-01-01

    This study explores difficulties that prospective elementary mathematics teachers have with the concepts of ratio and proportion, mainly when they are engaged in solving problems using algorithm procedures. These difficulties can be traced back to earlier experiences when they were students of junior and high school. The reflection on these…

  12. Proportionality: A Unifying Theme for the Middle Grades.

    ERIC Educational Resources Information Center

    Lanius, Cynthia S.; Williams, Susan E.

    2003-01-01

    Explains how middle school mathematics topics are often taught as separate, discrete topics without a unifying thread. Discusses the importance of proportionality as a concept with the potential to untie, relate, and clarify many important, complex middle grades ideas into a cohesive theme. (YDS)

  13. Making Sense of Fractions, Ratios, and Proportions. 2002 Yearbook.

    ERIC Educational Resources Information Center

    Litwiller, Bonnie, Ed.; Bright, George, Ed.

    This yearbook contains articles that give insight into students' thinking about factions, ratios, and proportions. Suggestions are offered on how to develop the concepts and skills associated with these topics. The book is divided into elementary, middle school, and professional development sections. Chapters include: (1) "The Development of…

  14. Grayscale and proportion-corrected optical coherence tomography images.

    PubMed

    Ishikawa, H; Gürses-Ozden, R; Hoh, S T; Dou, H L; Liebmann, J M; Ritch, R

    2000-01-01

    The commercially available optical coherence tomography (OCT) scanner displays images in a pre-set window regardless of the projected scan length on the retinal surface. The aim of this study was to demonstrate the true dimensions of proportion-corrected OCT images and the additional information present in grayscale images. OCT raw data were exported to an IBM-compatible PC and processed to show grayscale and proportion-corrected images using an automated software of our own design. Eyes with cystoid macular edema and retinal pigment detachment were analyzed. Grayscale images showed a finer gradation of signal reflectance. Scan lengths of 2, 4, 6, and 8 mm on the retinal surface showed different qualitative appearances using proportion-corrected software from the printed or on-screen images. Grayscale OCT images can be used to demonstrate additional information not present in false-color images. The disparity between the standard OCT image format and proportion-corrected images emphasizes the need for quantitative rather than qualitative evaluation of retinal dimensions and internal reflectance.

  15. High condylectomy versus proportional condylectomy: is secondary orthognathic surgery necessary?

    PubMed

    Fariña, R; Olate, S; Raposo, A; Araya, I; Alister, J P; Uribe, F

    2016-01-01

    The objective of this study was to assess the need for secondary orthognathic surgery in patients undergoing two different condylectomy protocols for active unilateral condylar hyperplasia (UCH). A retrospective cohort study evaluated UCH patients treated by condylectomy. Two groups were established: group 1 comprised those who had undergone a high condylectomy (5 mm removed) and group 2 comprised those who had undergone a proportional condylectomy (removing the difference observed between the measurements of the hyperplastic and the healthy side). Data analysis was done with the Levene test and t-test; a P-value of <0.05 indicated a statistically significant relationship. Forty-nine patients, with an average age of 19.83 years, were analyzed; 11 were included in group 1 and 38 in group 2. There was no statistical difference between the two groups with regard to age or sex (P=0.781). An average of 5.81 mm was removed in the high condylectomy group, while an average of 9.28 mm was removed in the proportional condylectomy group; this difference was statistically significant (P=0.042). Comparing the two groups, proportional condylectomy reduced the need for secondary orthognathic surgery (P<0.001). The proportional condylectomy can be used as the sole surgical treatment in cases of UCH, thus avoiding the need for secondary orthognathic surgery.

  16. The equivalence of two phylogenetic biodiversity measures: the Shapley value and Fair Proportion index.

    PubMed

    Hartmann, Klaas

    2013-11-01

    Most biodiversity conservation programs are forced to prioritise species in order to allocate their funding. This paper contains a mathematical proof that provides biological support for one common approach based on phylogenetic indices. Phylogenetic trees describe the evolutionary relationships between a group of taxa. Two indices for computing the distinctiveness of each taxon in a phylogenetic tree are considered here-the Shapley value and the Fair Proportion index. These indices provide a measure of the importance of each taxon for overall biodiversity and have been used to prioritise taxa for conservation. The Shapley value is the biodiversity contribution a taxon is expected to make if all taxa are equally likely to become extinct. This interpretation makes it appealing to use the Shapley value in biodiversity conservation applications. The Fair Proportion index lacks a convenient interpretation, however it is significantly easier to calculate and understand. It has been empirically observed that there is a high correlation between the two indices. This paper shows the mathematical basis for this correlation and proves that as the number of taxa increases, the indices become equivalent. Consequently in biodiversity prioritisation the simpler Fair Proportion index can be used whilst retaining the appealing interpretation of the Shapley value.

  17. Modified entropic force

    SciTech Connect

    Gao Changjun

    2010-04-15

    The theory of statistical thermodynamics tells us the equipartition law of energy does not hold in the limit of very low temperatures. It is found the Debye model is very successful in explaining the experimental results for most of the solid objects. Motivated by this fact, we modify the entropic force formula which is proposed very recently. Since the Unruh temperature is proportional to the strength of the gravitational field, so the modified entropic force formula is an extension of the Newtonian gravity to the weak field. On the contrary, general relativity extends Newtonian gravity to the strong field case. Corresponding to Debye temperature, there exists a Debye acceleration g{sub D}. It is found the Debye acceleration is g{sub D}=10{sup -15} N kg{sup -1}. This acceleration is very much smaller than the gravitational acceleration 10{sup -4} N kg{sup -1} which is felt by Neptune and the gravitational acceleration 10{sup -10} N kg{sup -1} felt by the Sun. Therefore, the modified entropic force can be very well approximated by the Newtonian gravity in the Solar System and in the Galaxy. With this Debye acceleration, we find the current cosmic speeding up can be explained without invoking any kind of dark energy.

  18. A ground reaction force analysis for designing a sustainable energy-harvesting stairway

    NASA Astrophysics Data System (ADS)

    Puspitarini, Debrina; Suzianti, Amalia; Rasyid, Harun Al; Priscandy, Nabila

    2016-06-01

    There are many issues of how energy is currently generated and consumed. These include the cost of harvesting energy, the ever-growing demand for it, and the ever-decreasing reserve of current most applicable energy resources. Numerous ways to exploit new sustainable potential energy sources have been pursued, one of which is to create an energy-harvester; a device that captures free potential energy, scattered around in its environment, and transform it into another form of energy. Using NPD approach, Puspitarini, Suzianti, and Al Rasyid (2016) has developed a conceptual design of an energy-harvesting device, which includes a selection of product specification options and a gear set layout design. In this study, a mockup was built for the experiment based on those product specification options. The experiment was conducted using AMTI Force Platform, and its results were processed using Factorial Design. This effort is to test which product specification option contributes the most to Ground Reaction Force (GRF) generation. The greater the generated GRF, the greater amount of electricity produced. A theoretical calculation of electromotive force was also conducted based on the experiment result and the gear set layout design. The result of this study was later discussed and used as a basis to develop further the stairway design.

  19. Multianode cylindrical proportional counter for high count rates

    DOEpatents

    Hanson, J.A.; Kopp, M.K.

    1980-05-23

    A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (< 60 keV) at count rates of greater than 10/sup 5/ counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

  20. Measurements of electron attachment by oxygen molecule in proportional counter

    NASA Astrophysics Data System (ADS)

    Tosaki, M.; Kawano, T.; Isozumi, Y.

    2013-11-01

    We present pulse height measurements for 5-keV Auger electrons from a radioactive 55Fe source mounted at the inner cathode surface of cylindrical proportional counter, which is operated with CH4 admixed dry air or N2. A clear shift of the pulse height has been observed by varying the amount of the admixtures; the number of electrons, created in the primary ionization by Auger electrons, is decreased by the electron attachment of the admixtures during their drift from the place near the source to the anode wire. The large gas amplification (typically 104) in the secondary ionization of proportional counter makes it possible to investigate a small change in the number of primary electrons. The electron attenuation cross-section of O2 has been evaluated by analyzing the shifts of the pulse height caused by the electron attachment to dry air and N2.

  1. Multianode cylindrical proportional counter for high count rates

    DOEpatents

    Hanson, James A.; Kopp, Manfred K.

    1981-01-01

    A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (<60 keV) at count rates of greater than 10.sup.5 counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

  2. Digital neutron radiography using plane converters with multiwire proportional chambers

    SciTech Connect

    Kaplan, S.N.; Director, B.A.; Perez-Mendez, V.; Valentine, K.H.

    1981-12-01

    The work described here was completed more than three years ago, and represents, in large part the PhD and MS thesis research of two of the present authors. Much of it has been reported previously elsewhere. It constitutes an effort to develop and study a moderately low cost, moderate resolution, high sensitivity, on-line method for digital neutron radiography, intended for use where neutron fluence was limited by source strength, or received dose. The basic imaging system consisted of a position-sensitive gas proportional chamber together with its associated imaging electronics, and a plane neutron converter. Enriched-boron, gadolinium, and polyethylene (for fast neutrons) converters were analyzed and tested. Some work was done on digital data enhancement, and efforts to improve spatial resolution included pressurizing the proportional-chamber gas to reduce the track lengths of the neutron-interaction products.

  3. Robotic lower limb exoskeletons using proportional myoelectric control.

    PubMed

    Ferris, Daniel P; Lewis, Cara L

    2009-01-01

    Robotic lower limb exoskeletons have been built for augmenting human performance, assisting with disabilities, studying human physiology, and re-training motor deficiencies. At the University of Michigan Human Neuromechanics Laboratory, we have built pneumatically-powered lower limb exoskeletons for the last two purposes. Most of our prior research has focused on ankle joint exoskeletons because of the large contribution from plantar flexors to the mechanical work performed during gait. One way we control the exoskeletons is with proportional myoelectric control, effectively increasing the strength of the wearer with a physiological mode of control. Healthy human subjects quickly adapt to walking with the robotic ankle exoskeletons, reducing their overall energy expenditure. Individuals with incomplete spinal cord injury have demonstrated rapid modification of muscle recruitment patterns with practice walking with the ankle exoskeletons. Evidence suggests that proportional myoelectric control may have distinct advantages over other types of control for robotic exoskeletons in basic science and rehabilitation.

  4. What proportion of congenital abnormalities can be prevented?

    PubMed Central

    Czeizel, A E; Intôdy, Z; Modell, B

    1993-01-01

    OBJECTIVE--To estimate the proportion of preventable congenital abnormalities in Hungary. DESIGN--Analysis of available Hungarian data-bases and of the effectiveness of primary, secondary, and tertiary preventive methods. SETTING--Databases of ad hoc epidemiological studies and of the Hungarian congenital abnormality registry. MAIN OUTCOME MEASURES--Prevalence at birth and prevalence after prevention in 73 congenital abnormality types or groups. RESULTS--Preventive methods are available for 51 (70%) of the 73 congenital abnormality types or groups evaluated. The birth prevalence of all congenital abnormalities could be reduced from 65 to 26 per 1000; thus 39 per 1000 (60%) are preventable. Without congenital dislocation of the hip, which is unusually common in Hungary, the preventable proportion of congenital abnormalities is 52%. CONCLUSION--Many congenital abnormalities can be prevented, but as they do not represent a single pathological category there is no single strategy for their prevention. Images p502-a p503-a PMID:8448464

  5. Transmission Line Properties of Nickel-Bodied Proportional Counters

    NASA Astrophysics Data System (ADS)

    Ryu, Jennifer

    2008-10-01

    Simultaneous measurements of neutral current and charged current neutrino scattering events allowed the Sudbury Neutrino Observatory (SNO) to demonstrate definitively neutrino oscillation. The three phases of the SNO detector are distinguished by different techniques of detecting the neutrons produced by neutral current neutrino scattering. In the final phase, nickel-bodied proportional counters filled with ^3He were used as neutral current detectors (NCDs) by observing the charged particles produced by neutron capture on ^3He. If we can understand the electrical transmission properties of the NCDs, we can use the different pulse shapes produced by neutron captures compared to those of alphas to distinguish these events and gain more sensitivity to the neutral current events. We found that because of the ferromagnetism of the nickel, standard calculations provided for proportional counters are not accurate enough. To obtain a better calculation, we directly measured the electrical properties of the transmission line as a function of frequency. This is a presentation of our results.

  6. Measurements of the performance of multiwire proportional chambers

    NASA Technical Reports Server (NTRS)

    Austin, R. W.; Eglitis, A.; Gregory, J. C.; Metzger, S. A.; Parnell, T. A.; Rutledge, H. F.; Selig, W.; Cumings, N. P.

    1973-01-01

    Data are presented that may be useful in formulating engineering specifications and test procedures for the proportional counter hodoscope to be flown as part of the High Energy Cosmic Ray Experiment on the High Energy Astronomy Observatory (HEAO), Mission A. A collection of preliminary data taken in laboratory tests of multiwire counters with an anode wire spacing of 5 mm and cathode gap spacing of 1 cm is presented. The data are from laboratory development models or counters for balloon flights and were selected to illustrate several aspects of proper and improper counter performance. Most of the data were taken from a large proportional counter hodoscope which has an active area of 0.5 by 0.5 m and 104 wires per plane.

  7. Robotic Lower Limb Exoskeletons Using Proportional Myoelectric Control

    PubMed Central

    Ferris, Daniel P.; Lewis, Cara L.

    2010-01-01

    Robotic lower limb exoskeletons have been built for augmenting human performance, assisting with disabilities, studying human physiology, and re-training motor deficiencies. At the University of Michigan Human Neuromechanics Laboratory, we have built pneumatically-powered lower limb exoskeletons for the last two purposes. Most of our prior research has focused on ankle joint exoskeletons because of the large contribution from plantar flexors to the mechanical work performed during gait. One way we control the exoskeletons is with proportional myoelectric control, effectively increasing the strength of the wearer with a physiological mode of control. Healthy human subjects quickly adapt to walking with the robotic ankle exoskeletons, reducing their overall energy expenditure. Individuals with incomplete spinal cord injury have demonstrated rapid modification of muscle recruitment patterns with practice walking with the ankle exoskeletons. Evidence suggests that proportional myoelectric control may have distinct advantages over other types of control for robotic exoskeletons in basic science and rehabilitation. PMID:19964579

  8. Intelligent automated control of life support systems using proportional representations.

    PubMed

    Wu, Annie S; Garibay, Ivan I

    2004-06-01

    Effective automatic control of Advanced Life Support Systems (ALSS) is a crucial component of space exploration. An ALSS is a coupled dynamical system which can be extremely sensitive and difficult to predict. As a result, such systems can be difficult to control using deliberative and deterministic methods. We investigate the performance of two machine learning algorithms, a genetic algorithm (GA) and a stochastic hill-climber (SH), on the problem of learning how to control an ALSS, and compare the impact of two different types of problem representations on the performance of both algorithms. We perform experiments on three ALSS optimization problems using five strategies with multiple variations of a proportional representation for a total of 120 experiments. Results indicate that although a proportional representation can effectively boost GA performance, it does not necessarily have the same effect on other algorithms such as SH. Results also support previous conclusions that multivector control strategies are an effective method for control of coupled dynamical systems.

  9. Misregistration's effects on classification and proportion estimation accuracy

    NASA Technical Reports Server (NTRS)

    Juday, R. D.; Hall, F.

    1982-01-01

    The estimates of crop type and acreage are undertaken in the AgRISTARS program by registering multiple date acquisitions of small subareas of LANDSAT scenes (termed segments), and applying multispectral analysis to them. An important contribution to errors in classification and acreage estimates is misregistration between multiple acquisitions. The formula used to express this relationship is given and the operations applied are so shown in diagrams. The taking of a LANDSAT feature vector and the derivation of the brightness and greeness are illustrated. It is shown that for any given sensor IFOV geometry, typical populations of fields can be derived and histograms can be plotted of the number of fields against field size according to ground truth. As a function of the resolution element, the IFOV of the sensor can draw the proportion of pure pixels in a given crop. Because the thematic mapper has a smaller resolution, the proportion of pixels that are pure in any given area will be larger.

  10. Adjusted variable plots for Cox's proportional hazards regression model.

    PubMed

    Hall, C B; Zeger, S L; Bandeen-Roche, K J

    1996-01-01

    Adjusted variable plots are useful in linear regression for outlier detection and for qualitative evaluation of the fit of a model. In this paper, we extend adjusted variable plots to Cox's proportional hazards model for possibly censored survival data. We propose three different plots: a risk level adjusted variable (RLAV) plot in which each observation in each risk set appears, a subject level adjusted variable (SLAV) plot in which each subject is represented by one point, and an event level adjusted variable (ELAV) plot in which the entire risk set at each failure event is represented by a single point. The latter two plots are derived from the RLAV by combining multiple points. In each point, the regression coefficient and standard error from a Cox proportional hazards regression is obtained by a simple linear regression through the origin fit to the coordinates of the pictured points. The plots are illustrated with a reanalysis of a dataset of 65 patients with multiple myeloma.

  11. Quench gases for xenon- (and krypton-) filled proportional counters

    NASA Technical Reports Server (NTRS)

    Ramsey, B. D.; Agrawal, P. C.

    1988-01-01

    Xenon-filled proportional counters are used extensively in astronomy, particularly in the hard X-ray region. The choice of quench gas can have a significant effect on the operating characteristics of the instrument although the data necessary to make the choice are not easily obtainable. Results which detail the performance obtained from both cylindrical and parallel field geometries for a wide variety of readily available, ultrahigh or research grade purity, quench gases are presented.

  12. Equivalence Between Approximate Dynamic Inversion and Proportional-Integral Control

    DTIC Science & Technology

    2008-09-29

    systems that renders the closed-loop error dynamics independent of the reference model dynamics. The equivalent PI controller will be derived and both of...integral control, PI control . I. INTRODUCTION DYNAMIC inversion (DI) or feedback linearization isa popular control design method that is well suited for...Proportional-Integral (PI) model reference controller realiza- tion. The key characteristic of the equivalent PI controller is that it is largely independent

  13. An analysis of maxillary anterior teeth: facial and dental proportions.

    PubMed

    Hasanreisoglu, Ufuk; Berksun, Semih; Aras, Kerem; Arslan, Ilker

    2005-12-01

    The size and form of the maxillary anterior teeth are important in achieving pleasing dental and facial esthetics. However, little scientific data have been defined as criteria for evaluating these morphological features. This study analyzed the clinical crown dimensions of maxillary anterior teeth to determine whether consistent relationships exist between tooth width and several facial measurements in a subset of the Turkish population. Full-face and anterior tooth images of 100 Turkish dental students viewed from the front and engaged in maximum smiling were recorded with digital photography under standardized conditions. Gypsum casts of the maxillary arches of the subjects were also made. The dimensions of the anterior teeth, the occurrence of the golden ratio, the difference between the actual and perceived sizes, and the relationship between the anterior teeth and several facial measurements by gender were analyzed using the information obtained from both the computer images and the casts. One-sample, 2-sample, and paired t tests, and repeated-measures analysis of variance and Duncan multiple-range tests were performed to analyze the data (alpha=.05). The dimensions of the central incisors (P<.05) and canines (P<.01) varied by gender. The existence of the so-called "golden proportion" for the maxillary anterior teeth as a whole was not found. Significant differences emerged when the mean ratios between various perceived widths were compared with their ideal golden ratios (P<.01). Proportional relationships between the bizygomatic width and the width of the central incisor, and the intercanine distance and the interalar width in women were observed. The maxillary central incisor and canine dimensions of men were greater than those of women in the Turkish population studied, with the canines showing the greatest gender variation. Neither a golden proportion nor any other recurrent proportion for all anterior teeth was determined. Bizygomatic width and interalar

  14. Workability of Mass Concrete. Report 2. Supplemental Proportioning Parameters.

    DTIC Science & Technology

    1996-09-01

    proportions for mass concrete with assurance that the concrete will have adequate workability. The initial phase of this study was to obtain information...Corps of Engineers (HQUSACE), as a part of Civil Works Investigation Studies Work Unit 32768, "Workability of Mass Concrete ." The study was conducted...Paul F. Mlakar, Chief, Concrete and Materials Division (CMD), and Mr. Edward F. O’Neil, Acting Chief, Engineering Mechanics Branch (EMB), CMD. Dr

  15. THE ESSENTIAL DIFFERENCE BETWEEN THE TWO OPTIMUM PROPORTIONS FLOCCULATION RATIOS

    PubMed Central

    Boyd, William C.; Purnell, Marjorie A.

    1944-01-01

    The fact that the optimum proportion flocculation ratio is different when determined by the α (Dean and Webb) and β (Ramon) procedures is pointed out. It is demonstrated that this difference is a consequence of the difference in the two methods, and that the two optima, though they may in certain cases lie near together, can never coincide. A new ratio (the ε ratio), intermediate between the α and β ratios, and having theoretical advantages over both of them, is defined. PMID:19871416

  16. Proportional drift tubes for large area muon detectors

    NASA Technical Reports Server (NTRS)

    Cho, C.; Higashi, S.; Hiraoka, N.; Maruyama, A.; Okusawa, T.; Sato, T.; Suwada, T.; Takahashi, T.; Umeda, H.

    1985-01-01

    A proportional drift chamber which consists of eight rectangular drift tubes with cross section of 10 cm x 5 cm, a sense wire of 100 micron phi gold-plated tungsten wire and the length of 6 m, was tested using cosmic ray muons. Spatial resolution (rms) is between 0.5 and 1 mm over drift space of 50 mm, depending on incident angle and distance from sense wire.

  17. Automatic method to manufacture 2D Multiwire Proportional Counter frames

    NASA Astrophysics Data System (ADS)

    Martínez, J. C.; Ramos-Lerate, I.; Fernández, F.; Beltrán, D.; Bordas, J.

    2007-04-01

    In this paper, a complete solution to manufacture anodes and cathodes for a Multiwire Proportional Counter (MWPC) is described. The solution consists of a semiautomatic winding machine and a soldering method by radiation. This method allows manufacturing one frame (electrode) in 3 h with a minimum human intervention. The machine can work with several types of frames and a great accuracy in the position and the stress of the wires can be achieved.

  18. A complete database for the Einstein imaging proportional counter

    NASA Technical Reports Server (NTRS)

    Helfand, David J.

    1991-01-01

    A complete database for the Einstein Imaging Proportional Counter (IPC) was completed. The original data that makes up the archive is described as well as the structure of the database, the Op-Ed analysis system, the technical advances achieved relative to the analysis of (IPC) data, the data products produced, and some uses to which the database has been put by scientists outside Columbia University over the past year.

  19. Energy Proportionality and Performance in Data Parallel Computing Clusters

    SciTech Connect

    Kim, Jinoh; Chou, Jerry; Rotem, Doron

    2011-02-14

    Energy consumption in datacenters has recently become a major concern due to the rising operational costs andscalability issues. Recent solutions to this problem propose the principle of energy proportionality, i.e., the amount of energy consumedby the server nodes must be proportional to the amount of work performed. For data parallelism and fault tolerancepurposes, most common file systems used in MapReduce-type clusters maintain a set of replicas for each data block. A coveringset is a group of nodes that together contain at least one replica of the data blocks needed for performing computing tasks. In thiswork, we develop and analyze algorithms to maintain energy proportionality by discovering a covering set that minimizesenergy consumption while placing the remaining nodes in lowpower standby mode. Our algorithms can also discover coveringsets in heterogeneous computing environments. In order to allow more data parallelism, we generalize our algorithms so that itcan discover k-covering sets, i.e., a set of nodes that contain at least k replicas of the data blocks. Our experimental results showthat we can achieve substantial energy saving without significant performance loss in diverse cluster configurations and workingenvironments.

  20. A Method to Quantify Mouse Coat-Color Proportions

    PubMed Central

    Ounpraseuth, Songthip; Rafferty, Tonya M.; McDonald-Phillips, Rachel E.; Gammill, Whitney M.; Siegel, Eric R.; Wheeler, Kristin L.; Nilsson, Erik A.; Cooney, Craig A.

    2009-01-01

    Coat-color proportions and patterns in mice are used as assays for many processes such as transgene expression, chimerism, and epigenetics. In many studies, coat-color readouts are estimated from subjective scoring of individual mice. Here we show a method by which mouse coat color is quantified as the proportion of coat shown in one or more digital images. We use the yellow-agouti mouse model of epigenetic variegation to demonstrate this method. We apply this method to live mice using a conventional digital camera for data collection. We use a raster graphics editing program to convert agouti regions of the coat to a standard, uniform, brown color and the yellow regions of the coat to a standard, uniform, yellow color. We use a second program to quantify the proportions of these standard colors. This method provides quantification that relates directly to the visual appearance of the live animal. It also provides an objective analysis with a traceable record, and it should allow for precise comparisons of mouse coats and mouse cohorts within and between studies. PMID:19404391

  1. Broad band imaging with an imaging gas scintillation proportional counter

    NASA Astrophysics Data System (ADS)

    Lum, Kenneth S. K.

    1987-12-01

    A large imaging gas scintillation proportional counter (LIGSPC) has been built and calibrated at the Columbia Astrophysics Laboratory. This instrument combines the good energy resolution of a gas scintillation proportional counter with the good spatial resolution of a multiwire proportional counter. We present experimental results obtained with this detector and interpret them in terms of the physical processes underlying its operation. A coded aperture mask whose pattern is based on a pseudorandom sequence has been tested with the LIGSPC. We discuss the effects that several physical design limitations have on the image deconvolution and compare analytical, simulated, and experimental results. Placed at the focal plane of a grazing incidence mirror and a coded aperture mask, the LIGSPC forms the basis of a broad band X-ray imaging spectrophotometer (BBXRIS) for the study of cosmic X-ray sources. We discuss the principles involved in the design of an experiment based on the BBXRIS concept and look at two specific examples, preparations for which are now underway.

  2. Is proportion burned severely related to daily area burned?

    NASA Astrophysics Data System (ADS)

    Birch, Donovan S.; Morgan, Penelope; Kolden, Crystal A.; Hudak, Andrew T.; Smith, Alistair M. S.

    2014-05-01

    The ecological effects of forest fires burning with high severity are long-lived and have the greatest impact on vegetation successional trajectories, as compared to low-to-moderate severity fires. The primary drivers of high severity fire are unclear, but it has been hypothesized that wind-driven, large fire-growth days play a significant role, particularly on large fires in forested ecosystems. Here, we examined the relative proportion of classified burn severity for individual daily areas burned that occurred during 42 large forest fires in central Idaho and western Montana from 2005 to 2007 and 2011. Using infrared perimeter data for wildfires with five or more consecutive days of mapped perimeters, we delineated 2697 individual daily areas burned from which we calculated the proportions of each of three burn severity classes (high, moderate, and low) using the differenced normalized burn ratio as mapped for large fires by the Monitoring Trends in Burn Severity project. We found that the proportion of high burn severity was weakly correlated (Kendall τ = 0.299) with size of daily area burned (DAB). Burn severity was highly variable, even for the largest (95th percentile) in DAB, suggesting that other variables than fire extent influence the ecological effects of fires. We suggest that these results do not support the prioritization of large runs during fire rehabilitation efforts, since the underlying assumption in this prioritization is a positive relationship between severity and area burned in a day.

  3. Maximum-likelihood estimation of admixture proportions from genetic data.

    PubMed Central

    Wang, Jinliang

    2003-01-01

    For an admixed population, an important question is how much genetic contribution comes from each parental population. Several methods have been developed to estimate such admixture proportions, using data on genetic markers sampled from parental and admixed populations. In this study, I propose a likelihood method to estimate jointly the admixture proportions, the genetic drift that occurred to the admixed population and each parental population during the period between the hybridization and sampling events, and the genetic drift in each ancestral population within the interval between their split and hybridization. The results from extensive simulations using various combinations of relevant parameter values show that in general much more accurate and precise estimates of admixture proportions are obtained from the likelihood method than from previous methods. The likelihood method also yields reasonable estimates of genetic drift that occurred to each population, which translate into relative effective sizes (N(e)) or absolute average N(e)'s if the times when the relevant events (such as population split, admixture, and sampling) occurred are known. The proposed likelihood method also has features such as relatively low computational requirement compared with previous ones, flexibility for admixture models, and marker types. In particular, it allows for missing data from a contributing parental population. The method is applied to a human data set and a wolflike canids data set, and the results obtained are discussed in comparison with those from other estimators and from previous studies. PMID:12807794

  4. Proportion of work appropriate for pharmacy technicians in anticoagulation clinics.

    PubMed

    Kuhn, Hayden; Park, Angela; Kim, Bo; Lukesh, William; Rose, Adam

    2016-03-01

    Results of a two-part study to determine the proportion of anticoagulation clinic (AC) work that could potentially be shifted from a pharmacist to a clinical pharmacy technician (CPT) are presented. In part 1 of the study, a group of eight clinical pharmacists and four CPTs from Veterans Affairs (VA) ACs used a modified Delphi process to categorize AC tasks as appropriate or inappropriate for a fully trained, licensed CPT. In part 2, a three-day time study was conducted at an AC staffed by one clinical pharmacist to determine the amounts of pharmacist time spent performing the tasks delineated through the Delphi process. Based on the time study data and task appropriateness categorizations, the proportion of AC work that might be appropriate for a CPT was estimated. Two levels of CPT-appropriate tasks were identified: those appropriate for any CPT and those appropriate only for an "advanced-practice CPT"; the latter category of tasks included conducting follow-up phone interviews with patients found to have in-range International Normalized Ratio values. The results of the time study indicated that 21% of the AC workload could be handled by a CPT and 41% could be handled by an advanced-practice CPT. Investigation of AC roles within the VA system suggested that well-trained pharmacy technicians can perform a substantial proportion of work in an AC, including some tasks performed by pharmacists. Copyright © 2016 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

  5. NASA CONNECT: Proportionality: The X-Plane Generation

    NASA Technical Reports Server (NTRS)

    2000-01-01

    'Proportionality: The X-Plane Generation' is the fifth of seven programs in the 1999-2000 NASA CONNECT series. Produced by NASA Langley Research Center's Office of Education, NASA CONNECT is an award-winning series of instructional programs designed to enhance the teaching of math, science and technology concepts in grades 5-8. NASA CONNECT establishes the 'connection' between the mathematics, science, and technology concepts taught in the classroom and NASA research. Each program in the series supports the national mathematics, science, and technology standards; includes a resource-rich teacher guide; and uses a classroom experiment and web-based activity to complement and enhance the math, science, and technology concepts presented in the program. NASA CONNECT is FREE and the programs in the series are in the public domain. Visit our web site and register. http://connect.larc.nasa.gov In 'Proportionality: The X-Plane Generation', students will learn why scaling and proportion are important factors in spacecraft design.

  6. Well-proportioned universes suppress the cosmic microwave background quadrupole

    NASA Astrophysics Data System (ADS)

    Weeks, J.; Luminet, J.-P.; Riazuelo, A.; Lehoucq, R.

    2004-07-01

    A widespread myth asserts that all small universe models suppress the cosmic microwave background (CMB) quadrupole. In actual fact, some models suppress the quadrupole while others elevate it, according to whether their low-order modes are weak or strong relative to their high-order modes. Elementary geometrical reasoning shows that a model's largest dimension determines the rough value lmin at which the CMB power spectrum l(l + 1) Cl/2π effectively begins; for cosmologically relevant models, lmin <= 3. More surprisingly, elementary geometrical reasoning shows that further reduction of a model's smaller dimensions - with its largest dimension held fixed - serves to elevate modes in the neighbourhood of lmin relative to the high-l portion of the spectrum, rather than suppressing them as one might naively expect. Thus among the models whose largest dimension is comparable to or less than the horizon diameter, the low-order Cl tend to be relatively weak in well-proportioned spaces (spaces whose dimensions are approximately equal in all directions) but relatively strong in oddly proportioned spaces (spaces that are significantly longer in some directions and shorter in others). We illustrate this principle in detail for the special cases of rectangular 3-tori and spherical spaces. We conclude that well-proportioned spaces make the best candidates for a topological explanation of the low CMB quadrupole observed by COBE and WMAP.

  7. Pharmacokinetics and dose proportionality of ceftibuten in men.

    PubMed Central

    Lin, C; Lim, J; Radwanski, E; Marco, A; Affrime, M

    1995-01-01

    The pharmacokinetics and dose proportionality of ceftibuten were evaluated in healthy male volunteers receiving single oral doses of 200, 400, and 800 mg of ceftibuten. The drug was absorbed with similar times to the maximum concentration of drug in plasma for all three doses. Concentrations of ceftibuten in plasma increased with increasing dose. Analysis of variance was carried out on the dose-adjusted values for the maximum concentration of drug in plasma and the area under the plasma concentration-time curve; the results indicated that the concentrations in plasma after the 200- and 400-mg doses were dose proportional, and after the 800-mg of dose they were less than dose proportional. The elimination half-life from plasma ranged from 2.0 to 2.3 h and was independent of dose. The total excretion of unchanged ceftibuten in urine accounted for 53 to 68% of the dose, and the renal clearance was estimated to be 53 to 61 ml/min after all doses. The amount of ceftibuten-trans, the major in vitro and in vivo conversion product of ceftibuten, was low in both plasma and urine. PMID:7726498

  8. A proportional mortality study of the acting profession.

    PubMed

    Depue, R H; Kagey, B T; Heid, M F

    1985-01-01

    Proportional mortality of actors and actresses was studied because cancers of many sites have been linked to hair dyes and cosmetics of which actors have been frequent users. Death records (1950-1978) for 2,618 white male and 838 white female members of Actors Equity and the Screen Actors Guild were compared with the U.S. mortality rats. Among males, significantly elevated proportional mortality ratios (PMR) were found for suicide (1.58), cirrhosis of the liver (1.99), all malignancies (1.15), and cancers of the colon/rectum (1.32), pancreas (1.51), and testes (2.37). Colon/rectum and pancreas cancers were not significantly elevated by proportional cancer mortality. Among females, significantly elevated PMRs were found for suicide (2.02) and lung cancer (2.20). Suicide in either sex was much more common in California than in New York. The elevated lung cancer in females was confined to Equity members. No elevations were found for cancers that have been related to hair dye or cosmetic use--ie, breast, ovary, bladder, leukemia, and lymphomas.

  9. The proportions of mutagens among chemicals in commerce.

    PubMed

    Zeiger, E; Margolin, B H

    2000-10-01

    It has been estimated that there are approximately 80,000 chemicals in commerce. Thus, it is not possible to test all these substances for mutagenicity and carcinogenicity; it is possible, however, to test or make estimates from selected subsets of these chemicals. For example, in the U.S. National Toxicology Program (NTP), 35% of the chemicals tested for mutagenicity in Salmonella were positive, as were 52% of the chemicals tested for carcinogenicity in rodents. In contrast, in the U.S. EPA Gene-Tox database, the proportions of chemicals that are Salmonella mutagens is 56%. These and other databases may be biased toward positive responses because they generally have been developed to look at specific structural or use classes of chemicals or chemicals suspected of genetic or carcinogenic activity. To address the question of the proportions of mutagens among all chemicals in commerce, a database of 100 chemicals was created from a random selection of chemicals in commerce. These chemicals were tested for mutagenicity in Salmonella and 22% were mutagenic. The mutagenicity of the 46 highest U.S. production organic chemicals was also compiled; 20% were mutagenic. These values provide a more accurate estimate of the proportions of mutagens among chemicals in commerce than can be derived from published mutagenicity databases.

  10. Force decomposition in robot force control

    NASA Technical Reports Server (NTRS)

    Murphy, Steve H.; Wen, John T.

    1991-01-01

    The unit inconsistency in force decomposition has motivated an investigation into the force control problem in multiple-arm manipulation. Based on physical considerations, it is argued that the force that should be controlled is the internal force at the specified frame in the payload. This force contains contributions due to both applied forces from the arms and the inertial force from the payload and the arms. A least-squares scheme free of unit inconsistency for finding this internal force is presented. The force control issue is analyzed, and an integral force feedback controller is proposed.

  11. Proportional assist ventilation decreases thoracoabdominal asynchrony and chest wall distortion in preterm infants.

    PubMed

    Musante, G; Schulze, A; Gerhardt, T; Everett, R; Claure, N; Schaller, P; Bancalari, E

    2001-02-01

    Thoracoabdominal asynchrony (TAA) and chest wall distortion (CWD) are commonly seen in preterm infants secondary to a highly compliant rib cage and poor compensation of distorting forces by inspiratory rib cage muscles. Continuous positive airway pressure (CPAP) reduces TAA and CWD by stenting the chest wall. We hypothesized that application of positive airway pressure only during inspiration and in proportion to an infant's inspiratory effort should have a similar but more pronounced effect than CPAP alone. A ventilator providing airway pressure changes in proportion to flow and volume generated by an infant (proportional assist ventilation) was used to unload the respiratory pump during inspiration. Ten preterm infants were studied [birth weight, 745 (635-1175) g; gestational age, 26.5 (24-31) wk; postnatal age 3 (1-7) d; medium (range)]. TAA and CWD were determined by respiratory inductive plethysmography. TAA was expressed as the phase angle between the rib cage and abdominal motion and CWD as the total compartmental displacement ratio. In addition, we measured tidal volume with a pneumotachograph and esophageal and airway pressure deflections with pressure transducers. Measurements were obtained during alternating periods of CPAP and two different degrees of support (Gain 1 = 1.09 +/- 0.68, Gain 2 = 1.84 +/- 0.84 cm H(2)O/mL) that were provided by a proportional assist ventilator. Phase angle and the total compartmental displacement ratio decreased with increasing gain compared with CPAP alone. Peak airway pressure increased from 0.6 to 3.8 to 7.6 cm H(2)O above positive end-expiratory pressure (PEEP) with CPAP, Gain 1, and Gain 2, respectively, as tidal volume increased from 2.8 to 4.1 to 4.7 mL/kg. Esophageal pressure changes decreased only little with increasing gain. Chest wall excursion increased and abdominal movement decreased, indicating a redistribution of tidal volume between chest and abdomen. We conclude that proportional assist ventilation reduces

  12. Strategic forces

    SciTech Connect

    Not Available

    1990-10-01

    The Air Force now plans to retain the Minuteman II and III missile force through fiscal year 2008. Introduced about 25 years ago, these missiles have served as a nuclear deterrence for longer than initially envisioned. Over the extended lives of the systems, questions have arisen over their continued reliability and operational effectiveness, particularly the Minuteman II system. Limited flight testing, due to a shortage of test missiles, and reduced reliability caused by age-related deterioration of guidance computers and propulsion motors are two factors undermining confidence in the Minuteman II. GAO believes that the Minuteman II could be retired before 1998 as presently contemplated under an assumption of a Strategic Arms Reduction Talks agreement. An alternative would be to reinstate the Air Force's plans to replace deteriorated missile components and acquire the assets needed to resume flight testing at rates necessary to restore and sustain confidence in the system's performance through fiscal year 2008. However, on the basis of current test schedules, GAO is concerned that components to test the missile's warheads will be depleted by about 1999.

  13. LDPC Codes with Minimum Distance Proportional to Block Size

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Jones, Christopher; Dolinar, Samuel; Thorpe, Jeremy

    2009-01-01

    Low-density parity-check (LDPC) codes characterized by minimum Hamming distances proportional to block sizes have been demonstrated. Like the codes mentioned in the immediately preceding article, the present codes are error-correcting codes suitable for use in a variety of wireless data-communication systems that include noisy channels. The previously mentioned codes have low decoding thresholds and reasonably low error floors. However, the minimum Hamming distances of those codes do not grow linearly with code-block sizes. Codes that have this minimum-distance property exhibit very low error floors. Examples of such codes include regular LDPC codes with variable degrees of at least 3. Unfortunately, the decoding thresholds of regular LDPC codes are high. Hence, there is a need for LDPC codes characterized by both low decoding thresholds and, in order to obtain acceptably low error floors, minimum Hamming distances that are proportional to code-block sizes. The present codes were developed to satisfy this need. The minimum Hamming distances of the present codes have been shown, through consideration of ensemble-average weight enumerators, to be proportional to code block sizes. As in the cases of irregular ensembles, the properties of these codes are sensitive to the proportion of degree-2 variable nodes. A code having too few such nodes tends to have an iterative decoding threshold that is far from the capacity threshold. A code having too many such nodes tends not to exhibit a minimum distance that is proportional to block size. Results of computational simulations have shown that the decoding thresholds of codes of the present type are lower than those of regular LDPC codes. Included in the simulations were a few examples from a family of codes characterized by rates ranging from low to high and by thresholds that adhere closely to their respective channel capacity thresholds; the simulation results from these examples showed that the codes in question have low

  14. Is the cross-bridge stiffness proportional to tension during muscle fiber activation?

    PubMed

    Colombini, Barbara; Nocella, Marta; Bagni, M Angela; Griffiths, Peter J; Cecchi, Giovanni

    2010-06-02

    The cross-bridge stiffness can be used to estimate the number of S1 that are bound to actin during contraction, which is a critical parameter for elucidating the fundamental mechanism of the myosin motor. At present, the development of active tension and the increase in muscle stiffness due to S1 binding to actin are thought to be linearly related to the number of cross-bridges formed upon activation. The nonlinearity of total stiffness with respect to active force is thought to arise from the contribution of actin and myosin filament stiffness to total sarcomere elasticity. In this work, we reexamined the relation of total stiffness to tension during activation and during exposure to N-benzyl-p-toluene sulphonamide, an inhibitor of cross-bridge formation. In addition to filament and cross-bridge elasticity, our findings are best accounted for by the inclusion of an extra elasticity in parallel with the cross-bridges, which is formed upon activation but is insensitive to the subsequent level of cross-bridge formation. By analyzing the rupture tension of the muscle (an independent measure of cross-bridge formation) at different levels of activation, we found that this additional elasticity could be explained as the stiffness of a population of no-force-generating cross-bridges. These findings call into question the assumption that active force development can be taken as directly proportional to the cross-bridge number. Copyright (c) 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  15. Is the Cross-Bridge Stiffness Proportional to Tension during Muscle Fiber Activation?

    PubMed Central

    Colombini, Barbara; Nocella, Marta; Bagni, M. Angela; Griffiths, Peter J.; Cecchi, Giovanni

    2010-01-01

    Abstract The cross-bridge stiffness can be used to estimate the number of S1 that are bound to actin during contraction, which is a critical parameter for elucidating the fundamental mechanism of the myosin motor. At present, the development of active tension and the increase in muscle stiffness due to S1 binding to actin are thought to be linearly related to the number of cross-bridges formed upon activation. The nonlinearity of total stiffness with respect to active force is thought to arise from the contribution of actin and myosin filament stiffness to total sarcomere elasticity. In this work, we reexamined the relation of total stiffness to tension during activation and during exposure to N-benzyl-p-toluene sulphonamide, an inhibitor of cross-bridge formation. In addition to filament and cross-bridge elasticity, our findings are best accounted for by the inclusion of an extra elasticity in parallel with the cross-bridges, which is formed upon activation but is insensitive to the subsequent level of cross-bridge formation. By analyzing the rupture tension of the muscle (an independent measure of cross-bridge formation) at different levels of activation, we found that this additional elasticity could be explained as the stiffness of a population of no-force-generating cross-bridges. These findings call into question the assumption that active force development can be taken as directly proportional to the cross-bridge number. PMID:20513402

  16. The elite athlete - assessing body shape, size, proportion and composition.

    PubMed

    Kerr, D A; Ackland, T R; Schreiner, A B

    1995-03-01

    In the quest to optimize performance of the elite athlete the sport scientist has sought to determine the ideal physique for a given sport or event. For some sports, specific structural characteristics offer definite performance advantages; for example in rowing, in addition to height, a large arm span has been identified as important. In other sports. such as long distance running, low levels of adiposity or 'fatness' appear to be linked with faster running times. There are four areas where appraisal of the athlete's physique can provide useful information: (1) identification of talented athletes; (2) to assess and monitor the growing athlete; (3) to monitor training and performance; and (4) to determine 'race weight' in weight-category sports. As a research tool a particular method must be reliable and valid. Other considerations include how expensive the method is, if it is suitable for a field situation and if large amounts of data on a number of subjects can be collected quickly. The method should be safe for both the athlete and the tester and provide useful feedback for the athlete or coach. Anthropometry, with training is able to fulfil most of these criteria and is the most widely used method of physique assessment in sports science. Large anthropometric data bases have been collected on elite athletes at Olympic games and world championships according to a standard protocol. Kinanthropometry, which has developed from anthropometry, is concerned with measurement and evaluation of different aspects of human movement and individual variation in body shape, size, proportion and composition. For the assessment of adiposity a sum of skinfolds, usually over six sites, is most commonly used rather than percentage body fat formulae. Muscle mass can be assessed indirectly through girth and corrected girth measurements. Limb lengths and breadths are used to assess skeletal structure and proportional differences in limb size. The anthropometric methods most commonly

  17. High Proportion of Male Faeces in Jaguar Populations

    PubMed Central

    Palomares, Francisco; Roques, Séverine; Chávez, Cuauhtémoc; Silveira, Leandro; Keller, Claudia; Sollmann, Rahel; do Prado, Denise Mello; Torres, Patricia Carignano; Adrados, Begoña; Godoy, José Antonio; de Almeida Jácomo, Anah Tereza; Tôrres, Natália Mundim; Furtado, Mariana Malzoni; López-Bao, José Vicente

    2012-01-01

    Faeces provide relevant biological information which includes, with the application of genetic techniques, the sex and identity of individuals that defecated, thus providing potentially useful data on the behaviour and ecology of individuals, as well as the dynamics and structure of populations. This paper presents estimates of the sex ratio of different felid species (jaguar, Panthera onca; puma, Puma concolor; and ocelot/margay, Leopardus pardalis/Leopardus wiedi) as observed in field collected faeces, and proposes several hypotheses that could explain the strikingly high proportion of faeces from male jaguars. The proportion of male and female faeces was estimated using a non-invasive faecal sampling method in 14 study areas in Mexico and Brazil. Faecal samples were genetically analysed to identify the species, the sex and the individual (the latter only for samples identified as belonging to jaguars). Considering the three species, 72.6% of faeces (n = 493) were from males; however, there were significant differences among them, with the proportion from males being higher for jaguars than for pumas and ocelots/margays. A male-bias was consistently observed in all study areas for jaguar faeces, but not for the other species. For jaguars the trend was the same when considering the number of individuals identified (n = 68), with an average of 4.2±0.56 faeces per male and 2.0±0.36 per female. The observed faecal marking patterns might be related to the behaviour of female jaguars directed toward protecting litters from males, and in both male and female pumas, to prevent interspecific aggressions from male jaguars. The hypothesis that there are effectively more males than females in jaguar populations cannot be discarded, which could be due to the fact that females are territorial and males are not, or a tendency for males to disperse into suboptimal areas for the species. PMID:23285226

  18. Assessment of Tooth Proportions in an Aesthetically Acceptable Smile

    PubMed Central

    Reddy, Munish; Raghav, Pradeep; Jain, Shalu; Anjum, Arbab; Misra, Vaibhav; Suri, Ragini

    2015-01-01

    Introduction: Aesthetic facial animation is mostly reported to be due to a close relationship between soft and hard tissue i.e. dynamic smile with appropriate tooth proportions. But variations in tooth size have been seen among various ethnic populations globally. Aim: To evaluate the size and morphology of maxillary anterior teeth, the tooth with maximum variation both mesiodistally and cervicoincisally. Also, the tooth to tooth ratio in percentage of the mean tooth sizes in both genders in patients with aesthetically acceptable smile decided by a panel in North Indian population. Materials and Methods: A total of 100 subjects (50 males and 50 females) were taken and a video clip of their dynamic smile was captured .The smiles were analyzed by a panel and the tooth proportions of the selected attractive smiles were evaluated in both males and females separately. Statistical analysis: Data obtained was subjected to statistical analysis using Microsoft Excel 2007 software; test used was Unpaired t-test and also Mean ± S.D., Variance, Ratio of W/L and its ranges were calculated. Significance is assessed at 5% level of significance. Results: The mesiodistal width and cervicoincisal length of maxillary central incisor was greater compared to lateral incisor and canine in both males and females. There was a statistically significant difference between the width/length ratio of maxillary anterior teeth between males and females.Canine and Lateral incisor showed maximum variation mesio-distally and cervico-incisally. Conclusion: A smile is more pleasing if the visible teeth are in proper morphological proportions. Thus, it relates that teeth play a vital role in increasing the attractiveness of a smile. The mean coronal width/length ratio displayed a more square like tooth form for both males and females. PMID:26023632

  19. Assessment of tooth proportions in an aesthetically acceptable smile.

    PubMed

    Jain, Sambhav; Reddy, Munish; Raghav, Pradeep; Jain, Shalu; Anjum, Arbab; Misra, Vaibhav; Suri, Ragini

    2015-04-01

    Aesthetic facial animation is mostly reported to be due to a close relationship between soft and hard tissue i.e. dynamic smile with appropriate tooth proportions. But variations in tooth size have been seen among various ethnic populations globally. To evaluate the size and morphology of maxillary anterior teeth, the tooth with maximum variation both mesiodistally and cervicoincisally. Also, the tooth to tooth ratio in percentage of the mean tooth sizes in both genders in patients with aesthetically acceptable smile decided by a panel in North Indian population. A total of 100 subjects (50 males and 50 females) were taken and a video clip of their dynamic smile was captured .The smiles were analyzed by a panel and the tooth proportions of the selected attractive smiles were evaluated in both males and females separately. Data obtained was subjected to statistical analysis using Microsoft Excel 2007 software; test used was Unpaired t-test and also Mean ± S.D., Variance, Ratio of W/L and its ranges were calculated. Significance is assessed at 5% level of significance. The mesiodistal width and cervicoincisal length of maxillary central incisor was greater compared to lateral incisor and canine in both males and females. There was a statistically significant difference between the width/length ratio of maxillary anterior teeth between males and females.Canine and Lateral incisor showed maximum variation mesio-distally and cervico-incisally. A smile is more pleasing if the visible teeth are in proper morphological proportions. Thus, it relates that teeth play a vital role in increasing the attractiveness of a smile. The mean coronal width/length ratio displayed a more square like tooth form for both males and females.

  20. High proportion of male faeces in jaguar populations.

    PubMed

    Palomares, Francisco; Roques, Séverine; Chávez, Cuauhtémoc; Silveira, Leandro; Keller, Claudia; Sollmann, Rahel; do Prado, Denise Mello; Torres, Patricia Carignano; Adrados, Begoña; Godoy, José Antonio; de Almeida Jácomo, Anah Tereza; Tôrres, Natália Mundim; Furtado, Mariana Malzoni; López-Bao, José Vicente

    2012-01-01

    Faeces provide relevant biological information which includes, with the application of genetic techniques, the sex and identity of individuals that defecated, thus providing potentially useful data on the behaviour and ecology of individuals, as well as the dynamics and structure of populations. This paper presents estimates of the sex ratio of different felid species (jaguar, Panthera onca; puma, Puma concolor; and ocelot/margay, Leopardus pardalis/Leopardus wiedi) as observed in field collected faeces, and proposes several hypotheses that could explain the strikingly high proportion of faeces from male jaguars. The proportion of male and female faeces was estimated using a non-invasive faecal sampling method in 14 study areas in Mexico and Brazil. Faecal samples were genetically analysed to identify the species, the sex and the individual (the latter only for samples identified as belonging to jaguars). Considering the three species, 72.6% of faeces (n = 493) were from males; however, there were significant differences among them, with the proportion from males being higher for jaguars than for pumas and ocelots/margays. A male-bias was consistently observed in all study areas for jaguar faeces, but not for the other species. For jaguars the trend was the same when considering the number of individuals identified (n = 68), with an average of 4.2±0.56 faeces per male and 2.0±0.36 per female. The observed faecal marking patterns might be related to the behaviour of female jaguars directed toward protecting litters from males, and in both male and female pumas, to prevent interspecific aggressions from male jaguars. The hypothesis that there are effectively more males than females in jaguar populations cannot be discarded, which could be due to the fact that females are territorial and males are not, or a tendency for males to disperse into suboptimal areas for the species.

  1. Functional hand proportion is approximated by the Fibonacci series.

    PubMed

    Choo, K W-Q; Quah, W-K; Chang, G-H; Chan, J Y

    2012-08-01

    The debatable relationship of functional human hand proportion with the Fibonacci series has remained an obscure scientific enigma short of clinical interest. The main difficulty of proving such a relationship lies in defining what should constitute true functional proportion. In this study, we re-evaluate this unique relationship using hand flexion creases as anatomical surrogates for the functional axes of joint rotation. Standardised desktop photocopies of palmar views of both hands in full digital extension and abduction were obtained from 100 healthy male volunteers of Chinese ethnicity. The functional axes were represented by the distal digital crease (distal interphalangeal joint, DIPJ), proximal digital crease (proximal interphalangeal joint, PIPJ), as well as the midpoint between the palmar digital and transverse palmar creases (metacarpophalangeal joint, MCPJ). The ratio of DIPJ-Fingertip:PIPJ-DIPJ:MCPJ-PIPJ (p3:p2:p1) was measured by two independent observers and represented as standard deviation about the mean, and then compared to the theoretical ratio of 1:1:2. Our results showed that, for the 2nd to 5th digits, the p2:p3 ratios were 0.97 ± ± 0.09, 1.10 ± 0.10, 1.04 ± 0.12, and 0.80 ± 0.08, respectively; whilst the p1:p2 ratios were 1.91 ± 0.17, 1.98 ± 0.14, 1.89 ± 0.16, and 2.09 ± 0.24, respectively. When the data were analysed for all digits, they showed a combined p3:p2:p1 ratio of 1:0.98:2.01. In conclusion, our results suggest that functional human hand proportion, as defined by flexion creases, is approximated by the Fibonacci series.

  2. New Bi-Proportional Methods for Bulgarian Parliamentary Elections

    NASA Astrophysics Data System (ADS)

    Konstantinov, Mihail; Yanev, Kostadin; Pelova, Galina

    2010-10-01

    A disadvantage of the existing bi-proportional system for the Bulgarian parliamentary elections is the large number of discordances (a party list with less votes gets more seats than a party list with more votes) in the seat distributions. Different schemes has been proposed to deal with this phenomenon. In this paper we propose two new methods: 1) augmentation of the electoral regions and 2) introduction of a new electoral region for accounting the votes cast abroad. In this way the number of discordances may be vastly reduced.

  3. Proportion of recovered goose and brant bands that are reported

    USGS Publications Warehouse

    Martinson, R.K.; McCann, J.A.

    1966-01-01

    A few more than one-third of the goose and brant bands recovered by hunters were reported to the Bird Banding Laboratory (a rate of 0.361) during the 1962-64 hunting seasons. We calculated this band-reporting rate by comparing the estimated number of goose and brant bands recovered by hunters, based on a mail questionnaire survey, with the number of bands actually reported to the Bird Banding Laboratory. This band-reporting rate is probably representative only of the 1962-65 period. It is likely that, in earlier years, a greater proportion (perhaps about 0.60) of recovered goose and brant bands were reported.

  4. Proportional counter windows for the Bragg Crystal Spectrometer on AXAF

    NASA Technical Reports Server (NTRS)

    Markert, T. H.; Bauer, J. M.; Canizares, C. R.; Isobe, T.; Nenonen, S.; O'Connor, J.; Schattenburg, M. L.; Flanagan, K. A.; Zombeck, M. V.

    1991-01-01

    A Bragg Crystal Spectrometer (BCS) using a gas flow proportional counter as its primary detector is among the instruments under development for AXAF. The BCS will employ windows of 1-micron-thick polyimide coated on both sides with 200 A of Al; this window composition, while X-ray transmitting, will leak gas at a lower rate than the polypropylene film-based windows formerly employed. Accounts are given of the results obtained with additional innovative X-ray window materials currently under development, including diamond and Si-enriched Si3N4.

  5. Gas amplification factor in neon-nitrogen filled proportional counters

    NASA Astrophysics Data System (ADS)

    Othman, A.

    1988-07-01

    The gas amplification factor in a cylindrical proportional counter filled with NeN 2 Penning mixtures has been measured (over the range 1 < A < 6.4 × 10 3) to verify the validity of the gas gain formulae of Rose and Korff, Khristov, Williams and Sara, Diethorn and Zastawny. This factor has been found to obey Zastawny's formula over the range of variables studied. The formula of Diethorn can be fitted only for small nitrogen concentrations (below 5 × 10 -4). Constants appropriate to the Zastawny and Diethorn formulae have been determined over a wide range of N 2 concentrations from spectroscopically pure Ne up to 11.1% N 2.

  6. Proportional counter windows for the Bragg Crystal Spectrometer on AXAF

    NASA Technical Reports Server (NTRS)

    Markert, T. H.; Bauer, J. M.; Canizares, C. R.; Isobe, T.; Nenonen, S.; O'Connor, J.; Schattenburg, M. L.; Flanagan, K. A.; Zombeck, M. V.

    1991-01-01

    A Bragg Crystal Spectrometer (BCS) using a gas flow proportional counter as its primary detector is among the instruments under development for AXAF. The BCS will employ windows of 1-micron-thick polyimide coated on both sides with 200 A of Al; this window composition, while X-ray transmitting, will leak gas at a lower rate than the polypropylene film-based windows formerly employed. Accounts are given of the results obtained with additional innovative X-ray window materials currently under development, including diamond and Si-enriched Si3N4.

  7. Asbestos disease in sheet metal workers: proportional mortality update

    SciTech Connect

    Michaels, D.; Zoloth, S.

    1988-01-01

    This paper, updating the findings of an earlier study, provides additional evidence that sheet metal workers in the construction trades are at increased risk for asbestos-related disease. A proportional analysis of cause of death among 331 New York sheet metal workers found a significantly elevated PMR for lung cancer (PMR = 186). In addition, there were six deaths attributable to mesothelioma (three classified as lung cancer deaths) and three death certificates mentioned asbestosis or pulmonary fibrosis, although none of these three deaths were attributed to these diseases.

  8. High speed pulse digitization in driftless gas scintillation proportional counters

    SciTech Connect

    Valero, J.; Smith, A.; Peacock, A.

    1988-06-01

    In a driftless gas scintillation proportional counter the observed light burst profile provides a wealth of information both about the incident photon and the transit of the electron cloud through the scintillation region. The different features of such profiles are difficult to separate with conventional analog electronics. In this work the authors apply the technique of high speed pulse digitization to the problem. They show that by this technique not only can the performance of the instrument be improved (e.g. background rejection) but valuable data can be obtained regarding the design of both the gas cell and the analysis electronics.

  9. Wealth distribution under Yard-Sale exchange with proportional taxes

    NASA Astrophysics Data System (ADS)

    Bustos-Guajardo, R.; Moukarzel, Cristian F.

    2016-03-01

    Recent analysis of a Yard-Sale (YS) exchange model supplemented with redistributive proportional taxation suggested an asymptotic behavior P(w)˜1/wμ for the wealth distribution, with a parameter-dependent exponent μ. Revisiting this problem, it is here shown analytically, and confirmed by extensive numerical simulation, that the asymptotic behavior of P(w) is not power-law but rather a Gaussian. When taxation is weak, we furthermore show that a restricted-range power-law behavior appears for wealths around the mean value. The corresponding power-law exponent equals 3/2 when the return distribution has zero mean.

  10. The enigma of facial beauty: esthetics, proportions, deformity, and controversy.

    PubMed

    Naini, Farhad B; Moss, James P; Gill, Daljit S

    2006-09-01

    The study of the face and the ability to alter its form have fascinated mankind for thousands of years. The clinical ability to alter dentofacial form, whether through orthodontics, facial growth modification, or surgery, requires an understanding of facial beauty, including the evaluation of facial esthetics, proportions, and symmetry. The purposes of this article were to give a brief contemporary overview of our concepts of facial beauty and esthetics and to consider a long-standing and controversial debate on the treatment of patients with dentofacial deformities.

  11. Improvement of force factor of magnetostrictive vibration power generator for high efficiency

    SciTech Connect

    Kita, Shota Ueno, Toshiyuki; Yamada, Sotoshi

    2015-05-07

    We develop high power magnetostrictive vibration power generator for battery-free wireless electronics. The generator is based on a cantilever of parallel beam structure consisting of coil-wound Galfenol and stainless plates with permanent magnet for bias. Oscillating force exerted on the tip bends the cantilever in vibration yields stress variation of Galfenol plate, which causes flux variation and generates voltage on coil due to the law of induction. This generator has advantages over conventional, such as piezoelectric or moving magnet types, in the point of high efficiency, highly robust, and low electrical impedance. Our concern is the improvement of energy conversion efficiency dependent on the dimension. Especially, force factor, the conversion ratio of the electromotive force (voltage) on the tip velocity in vibration, has an important role in energy conversion process. First, the theoretical value of the force factor is formulated and then the validity was verified by experiments, where we compare four types of prototype with parameters of the dimension using 7.0 × 1.5 × 50 mm beams of Galfenol with 1606-turn wound coil. In addition, the energy conversion efficiency of the prototypes depending on load resistance was measured. The most efficient prototype exhibits the maximum instantaneous power of 0.73 W and energy of 4.7 mJ at a free vibration of frequency of 202 Hz in the case of applied force is 25 N. Further, it was found that energy conversion efficiency depends not only on the force factor but also on the damping (mechanical loss) of the vibration.

  12. Improvement of force factor of magnetostrictive vibration power generator for high efficiency

    NASA Astrophysics Data System (ADS)

    Kita, Shota; Ueno, Toshiyuki; Yamada, Sotoshi

    2015-05-01

    We develop high power magnetostrictive vibration power generator for battery-free wireless electronics. The generator is based on a cantilever of parallel beam structure consisting of coil-wound Galfenol and stainless plates with permanent magnet for bias. Oscillating force exerted on the tip bends the cantilever in vibration yields stress variation of Galfenol plate, which causes flux variation and generates voltage on coil due to the law of induction. This generator has advantages over conventional, such as piezoelectric or moving magnet types, in the point of high efficiency, highly robust, and low electrical impedance. Our concern is the improvement of energy conversion efficiency dependent on the dimension. Especially, force factor, the conversion ratio of the electromotive force (voltage) on the tip velocity in vibration, has an important role in energy conversion process. First, the theoretical value of the force factor is formulated and then the validity was verified by experiments, where we compare four types of prototype with parameters of the dimension using 7.0 × 1.5 × 50 mm beams of Galfenol with 1606-turn wound coil. In addition, the energy conversion efficiency of the prototypes depending on load resistance was measured. The most efficient prototype exhibits the maximum instantaneous power of 0.73 W and energy of 4.7 mJ at a free vibration of frequency of 202 Hz in the case of applied force is 25 N. Further, it was found that energy conversion efficiency depends not only on the force factor but also on the damping (mechanical loss) of the vibration.

  13. The proportion of elderly in Pennsylvania is slipping but....

    PubMed

    Waldman, H Barry; Cannella, Dolores; Perlman, Steven P

    2013-01-01

    Media reports describing the anticipated increase of tens of millions of elderly residents and their attendant billions of dollar costs for health services during the next decades are difficult for any person to place in proper perspective. As a result, these estimates become "just numbers" not actual people. Census Bureau reports are used at the national, state and county levels to provide an increased meaningful picture when the 65 and older population of Pennsylvania will increase to 22.6 percent of the state population. In 2000, 12.4 percent of the U.S. population was 65 years and older (15.6 percent in Pennsylvania, 1.9 million elderly). Only in the state of Florida was the proportion greater. In 2010, the proportion of elderly in the population of Pennsylvania ranked 4th (behind Florida, West Virginia and Maine). It was tied for 3rd (behind Florida and North Dakota) with 2.5 percent of the population 85 years and over. By 2030, the projected number of elderly in Pennsylvania (22.6 percent of the state population) will rank 11th. But ... "Starting on Jan 1, (2011) our 79-million-strong baby boomer generation will be turning 65 at the rate of one elderly every eight seconds.

  14. The arcsine is asinine: the analysis of proportions in ecology.

    PubMed

    Warton, David I; Hui, Francis K C

    2011-01-01

    The arcsine square root transformation has long been standard procedure when analyzing proportional data in ecology, with applications in data sets containing binomial and non-binomial response variables. Here, we argue that the arcsine transform should not be used in either circumstance. For binomial data, logistic regression has greater interpretability and higher power than analyses of transformed data. However, it is important to check the data for additional unexplained variation, i.e., overdispersion, and to account for it via the inclusion of random effects in the model if found. For non-binomial data, the arcsine transform is undesirable on the grounds of interpretability, and because it can produce nonsensical predictions. The logit transformation is proposed as an alternative approach to address these issues. Examples are presented in both cases to illustrate these advantages, comparing various methods of analyzing proportions including untransformed, arcsine- and logit-transformed linear models and logistic regression (with or without random effects). Simulations demonstrate that logistic regression usually provides a gain in power over other methods.

  15. Adaptive differences in the body proportions of large felids.

    PubMed

    Gonyea, W J

    1976-01-01

    Body proportions of eight species of large felids were studied and the relationship between their morphology, habitat structure and habitat utilization was analyzed. Both Panthera onca and Neofelis nebulosa are exclusive forest dwellers (found exclusively in high densly structured habitats). These felids have the relatively shortest anterior limbs and lumbar spine. In addition, P. onca has the relatively shortest posterior limbs of the large felids, while the posterior limbs of N. nebulosa are relatively long when compared with those of P. onca which seems to be an adaptation for jumping. All large fields use the anterior limbs to make primary contact with their prey. In addition, the prey taken by the forest fields can exceed their own body weight. On the other hand, the cheetah is found in low structured habitats (savanna), and it has the relatively longest limbs and lumbarspine of the large felids. But the cheetah's prey usually weigh less than its own body weight. The cheetah also employs a 'rapid pursuit phase' in hunting and is capable of overtaking its prey. The lion, however, was found to have the body proportions of a forest felid, yet it also resides in low structured habitats. It is postulated that the utilization of large prey by the lion limits the possibilities for morphological adaptations for speed. To increase hunting efficiency, reproductive success, and territorial defense on the plains, lions form prides.

  16. [Rational range and optimum proportion of energy input in farmland].

    PubMed

    Yin, J; Zhou, N; Gao, Z; Yang, W; Miao, G

    2000-04-01

    There exists a rational range of artificial supplemental energy inputs in fields. In the range, the inputs can improve the yield and the output/input ratio. The rational range of energy input in total energy output is bigger than that in the output/input ratio. It is bigger in low yield fields than high yield fields, which suggests that increasing artificial supplemental energy input can increase the production of low yield fields as same as high yield fields. In the rational range of energy input, there exist high efficient lines in water and fertilizer inputs. The highest efficiency occurs when the rational inputs of water and fertilizer occur in these two lines. There also exist optimum lines of energy and economy input proportions. In the two lines, the proportions of energy and economy output/input of water and fertilizer inputs are the highest, which are the optimum of water and fertilizer inputs. Water and fertilizer may replace each other for equal yields, but would result in a decrease in the output/input ratio.

  17. Conscious and unconscious proportion effects in masked priming.

    PubMed

    Van den Bussche, Eva; Segers, Gitte; Reynvoet, Bert

    2008-12-01

    The global neuronal workspace theory [Dehaene, S., & Naccache, L. (2001). Towards a cognitive neuroscience of consciousness: basic evidence and a workspace framework. Cognition, 79, 1-37.] proposes that it is impossible for an unconscious stimulus to be used strategically to enhance task performance (bottom-up effect), while a fully consciously perceived stimulus can be used to improve task performance (top-down effect). Two experiments were designed to investigate these hypotheses. In a first experiment we investigated whether a manipulation of the proportion of Arabic/number word targets had a top-down effect. Since the subjects were fully aware of the target, we expected that this manipulation could be used to enhance task performance. In a second experiment we determined whether a manipulation of the proportion of Arabic/number word primes had a bottom-up effect. Since the subjects were unaware of the prime, we hypothesized that they would be unable to use the manipulation to enhance task performance and therefore the manipulation would have no effect. Both hypotheses were largely confirmed.

  18. Fiber Contraction Approaches for Improving CMC Proportional Limit

    NASA Technical Reports Server (NTRS)

    DiCarlo, James A.; Yun, Hee Mann

    1997-01-01

    The fact that the service life of ceramic matrix composites (CMC) decreases dramatically for stresses above the CMC proportional limit has triggered a variety of research activities to develop microstructural approaches that can significantly improve this limit. As discussed in a previous report, both local and global approaches exist for hindering the propagation of cracks through the CMC matrix, the physical source for the proportional limit. Local approaches include: (1) minimizing fiber diameter and matrix modulus; (2) maximizing fiber volume fraction, fiber modulus, and matrix toughness; and (3) optimizing fiber-matrix interfacial shear strength; all of which should reduce the stress concentration at the tip of cracks pre existing or created in the matrix during CMC service. Global approaches, as with pre-stressed concrete, center on seeking mechanisms for utilizing the reinforcing fiber to subject the matrix to in-situ compressive stresses which will remain stable during CMC service. Demonstrated CMC examples for the viability of this residual stress approach are based on strain mismatches between the fiber and matrix in their free states, such as, thermal expansion mismatch and creep mismatch. However, these particular mismatch approaches are application limited in that the residual stresses from expansion mismatch are optimum only at low CMC service temperatures and the residual stresses from creep mismatch are typically unidirectional and difficult to implement in complex-shaped CMC.

  19. Ancestry informative markers and admixture proportions in northeastern Mexico.

    PubMed

    Martinez-Fierro, Margarita L; Beuten, Joke; Leach, Robin J; Parra, Esteban J; Cruz-Lopez, Miguel; Rangel-Villalobos, Hector; Riego-Ruiz, Lina R; Ortiz-Lopez, Rocio; Martinez-Rodriguez, Herminia G; Rojas-Martinez, Augusto

    2009-09-01

    To investigate the ancestral admixture in the Mestizo population in northeastern Mexico, we genotyped 74 ancestral informative markers (AIMs) and 15 Y-single-nucleotide polymorphisms (Y-SNPs) in 100 individuals. The Native American contribution is 56% (range: 27.4-81.2%), the European contribution is 38% (range: 16.7-70.5%) and the West African contribution is 6%. The results show a higher European contribution than was reported in other similar studies in the country, albeit with a predominant Native American ancestry. No remarkable differences in the ancestry proportions were observed using subgroups of 74, 54, 34 and 24 AIMs. The paternal lineage calculated by genotyping of 15 Y-SNPs, shows a major component of European and Eurasian ancestry markers ( approximately 78%), compared with Amerindian ( approximately 12%) and African markers (10%). This information will set a reference for future determinations of admixture proportions in the Mestizo population from Mexico and for population-based association studies of complex diseases.

  20. Estimation of dental and facial proportions using height as criteria.

    PubMed

    Nalawade, Sumit Shivaji; Shinde, Sagar Kundlik; Pawar, Renuka Lalit; Gupta, Aditi; Kale, Vishwajeet Tulshidas; Janrao, Kunal Ashok

    2014-07-01

    Ideal dental restoration is one which not only restores optimal functions but also confirm to standard dental and facial relations. This is important to achieve long term patient satisfaction both with regard to esthetics as well as functions. Objective was to find a credible relationship between dental and facial proportions using height of individuals as the criteria in a specific group of population. To determine a regression equation for determination of various dental and facial proportions using height. One hundred and forty-four (n = 144) students, of which 91 were males (n = 91) and 53 were females (n = 53) of the dental college participated in this study. Height of the individual, the lower facial height, inter-incisal and inter-canine and inter-commissural width was measured as per protocol and resulting data was analyzed using SPSS 17 (SPSS Statistics for Windows, Version 17.0. Chicago SPSS Inc. Released 2008) version software regression equations were obtained. The study included 144 college students significant correlations were found between height of the individuals, inter-canine distance and lower facial height using Pearson correlation coefficient. The calculated values of t-test were significant. Regression equations were determined for determination of various parameters using height as the sole criteria. There exists a definite relationship between height of the individual and their dental and facial parameters in this group of population and values of maxillary anterior teeth can be determined using regression equations.

  1. Empirical Relationships between Species Richness, Evenness, and Proportional Diversity.

    PubMed

    Stirling, G; Wilsey, B

    2001-09-01

    Diversity (or biodiversity) is typically measured by a species count (richness) and sometimes with an evenness index; it may also be measured by a proportional statistic that combines both measures (e.g., Shannon-Weiner index or H'). These diversity measures are hypothesized to be positively and strongly correlated, but this null hypothesis has not been tested empirically. We used the results of Caswell's neutral model to generate null relationships between richness (S), evenness (J'), and proportional diversity (H'). We tested predictions of the null model against empirical relationships describing data in a literature survey and in four individual studies conducted across various scales. Empirical relationships between log S or J' and H' differed from the null model when <10 species were tested and in plants, vertebrates, and fungi. The empirical relationships were similar to the null model when >10 and <100 species were tested and in invertebrates. If >100 species were used to estimate diversity, the relation between log S and H' was negative. The strongest predictive models included log S and J'. A path analysis indicated that log S and J' were always negatively related, that empirical observations could not be explained without including indirect effects, and that differences between the partials may indicate ecological effects, which suggests that S and J' act like diversity components or that diversity should be measured using a compound statistic.

  2. Aesthetics of the Nasal Dorsum: Proportions, Light, and Shadow.

    PubMed

    Krane, Natalie A; Markey, Jeffrey D; Moneta, Lauren B; Kim, Michael M

    2017-04-01

    Due to its central location, the nose plays a prominent role in facial aesthetics. As tastes have shifted and techniques have advanced, the accepted "ideal" appearance and proportions of the nose have evolved over time. By assessing the aesthetics of the nasal dorsum through the use of lines and angles, one can more precisely elucidate a goal for the patient's postoperative nasal shape, which should, in turn, guide the surgeon to execute specific operative maneuvers needed to achieve that contour. In assessing the aesthetics of the nasal dorsum, practitioners calculate and observe aspects such as the paired dorsal aesthetic lines, the nasofrontal angle, and the nasofacial angle. There is also additional consideration given to nasal tip position as this must fit harmoniously with the shape of the dorsum. In contrast to the established aesthetic lines and angles, using nasal geometric polygons for the aesthetic evaluation and development of operative goals in rhinoplasty has recently been described in the literature. Constructed ideals, in the form of proportions, lines, and angles, should be used with caution, as there are many factors to consider in the aesthetic analysis of the nasal dorsum, including ethnic differences, and subjective and changing views of beauty. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  3. Estimation of Dental and Facial Proportions Using Height as Criteria

    PubMed Central

    Nalawade, Sumit Shivaji; Shinde, Sagar Kundlik; Pawar, Renuka Lalit; Gupta, Aditi; Kale, Vishwajeet Tulshidas; Janrao, Kunal Ashok

    2014-01-01

    Background: Ideal dental restoration is one which not only restores optimal functions but also confirm to standard dental and facial relations. This is important to achieve long term patient satisfaction both with regard to esthetics as well as functions. Objective was to find a credible relationship between dental and facial proportions using height of individuals as the criteria in a specific group of population. To determine a regression equation for determination of various dental and facial proportions using height. Materials and Methods: One hundred and forty-four (n = 144) students, of which 91 were males (n = 91) and 53 were females (n = 53) of the dental college participated in this study. Height of the individual, the lower facial height, inter-incisal and inter-canine and inter-commissural width was measured as per protocol and resulting data was analyzed using SPSS 17 (SPSS Statistics for Windows, Version 17.0. Chicago SPSS Inc. Released 2008) version software regression equations were obtained. Results: The study included 144 college students significant correlations were found between height of the individuals, inter-canine distance and lower facial height using Pearson correlation coefficient. The calculated values of t-test were significant. Regression equations were determined for determination of various parameters using height as the sole criteria. Conclusion: There exists a definite relationship between height of the individual and their dental and facial parameters in this group of population and values of maxillary anterior teeth can be determined using regression equations. PMID:25214728

  4. Characteristics of restructured beef steak with different proportions of walnut during frozen storage.

    PubMed

    Serrano, A; Cofrades, S; Jiménez-Colmenero, F

    2006-01-01

    Physicochemical (thawing loss, cooking loss, surface shrinkage, texture, colour and lipid oxidation) and sensory properties of restructured beef steak with different levels of added walnut (0%, 10% and 20%) were determined at various times during frozen storage up to 128 days. Cooking loss (CL), Kramer shear force (KSF) and binding strength (BS) of restructured beef decreased (P<0.05) as the proportion of walnut increased. Walnut enhanced (P<0.05) lightness and yellowness and reduced (P<0.05) redness. Frozen storage did not affect (P>0.05) CL, KSF and BS of restructured beef steak. Redness decreased (P<0.05) over storage for all samples. Lipid oxidation of restructured beef steak containing walnut was not a limiting factor for frozen stability of meat products. Frozen storage had no effect (P>0.05) on the sensory quality of restructured beef steak.

  5. Coriolis Force

    NASA Astrophysics Data System (ADS)

    Marciuc, Daly; Solschi, Viorel

    2017-04-01

    Understanding the Coriolis effect is essential for explaining the movement of air masses and ocean currents. The lesson we propose aims to familiarize students with the manifestation of the Coriolis effect. Students are guided to build, using the GeoGebra software, a simulation of the motion of a body, related to a rotating reference system. The mathematical expression of the Coriolis force is deduced, for particular cases, and the Foucault's pendulum is presented and explained. Students have the opportunity to deepen the subject, by developing materials related to topics such as: • Global Wind Pattern • Ocean Currents • Coriolis Effect in Long Range Shooting • Finding the latitude with a Foucault Pendulum

  6. Estimating proportions of objects from multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Horwitz, H. M.; Lewis, J. T.; Pentland, A. P.

    1975-01-01

    Progress is reported in developing and testing methods of estimating, from multispectral scanner data, proportions of target classes in a scene when there are a significiant number of boundary pixels. Procedures were developed to exploit: (1) prior information concerning the number of object classes normally occurring in a pixel, and (2) spectral information extracted from signals of adjoining pixels. Two algorithms, LIMMIX and nine-point mixtures, are described along with supporting processing techniques. An important by-product of the procedures, in contrast to the previous method, is that they are often appropriate when the number of spectral bands is small. Preliminary tests on LANDSAT data sets, where target classes were (1) lakes and ponds, and (2) agricultural crops were encouraging.

  7. The role of facial proportion in hair restoration surgery.

    PubMed

    Stough, D B; Schell, B J; Weyrich, R P

    1997-02-01

    Facial aesthetics involve basic artistic principles that relate individual features to the face as a whole. These principles, such as balance and proportion, are key elements in the development of hair restoration surgery and can be applied to reconstructive procedures for the trauma or burn patient. This paper describes the application of anthropometric and artistic principles used in hair reconstruction. Attention has been directed to the procedures used to determine hairline contour and placement, and certain aspects of frontotemporal recession management. The frontal hair has a profound effect on facial balance because of the major role hair plays in framing and visually enhancing the face. The presence of frontal hair and facial framing also serves to retain a vital element of autonomy in appearance for the individual.

  8. Penalized estimation for proportional hazards models with current status data.

    PubMed

    Lu, Minggen; Li, Chin-Shang

    2017-09-05

    We provide a simple and practical, yet flexible, penalized estimation method for a Cox proportional hazards model with current status data. We approximate the baseline cumulative hazard function by monotone B-splines and use a hybrid approach based on the Fisher-scoring algorithm and the isotonic regression to compute the penalized estimates. We show that the penalized estimator of the nonparametric component achieves the optimal rate of convergence under some smooth conditions and that the estimators of the regression parameters are asymptotically normal and efficient. Moreover, a simple variance estimation method is considered for inference on the regression parameters. We perform 2 extensive Monte Carlo studies to evaluate the finite-sample performance of the penalized approach and compare it with the 3 competing R packages: C1.coxph, intcox, and ICsurv. A goodness-of-fit test and model diagnostics are also discussed. The methodology is illustrated with 2 real applications. Copyright © 2017 John Wiley & Sons, Ltd.

  9. Response of a tissue equivalent proportional counter to neutrons

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Robbins, D. E.; Gibbons, F.; Braby, L. A.

    2002-01-01

    The absorbed dose as a function of lineal energy was measured at the CERN-EC Reference-field Facility (CERF) using a 512-channel tissue equivalent proportional counter (TEPC), and neutron dose equivalent response evaluated. Although there are some differences, the measured dose equivalent is in agreement with that measured by the 16-channel HANDI tissue equivalent counter. Comparison of TEPC measurements with those made by a silicon solid-state detector for low linear energy transfer particles produced by the same beam, is presented. The measurements show that about 4% of dose equivalent is delivered by particles heavier than protons generated in the conducting tissue equivalent plastic. c2002 Elsevier Science Ltd. All rights reserved.

  10. A Complete Public Archive for the Einstein Imaging Proportional Counter

    NASA Technical Reports Server (NTRS)

    Helfand, David J.

    1996-01-01

    Consistent with our proposal to the Astrophysics Data Program in 1992, we have completed the design, construction, documentation, and distribution of a flexible and complete archive of the data collected by the Einstein Imaging Proportional Counter. Along with software and data delivered to the High Energy Astrophysics Science Archive Research Center at Goddard Space Flight Center, we have compiled and, where appropriate, published catalogs of point sources, soft sources, hard sources, extended sources, and transient flares detected in the database along with extensive analyses of the instrument's backgrounds and other anomalies. We include in this document a brief summary of the archive's functionality, a description of the scientific catalogs and other results, a bibliography of publications supported in whole or in part under this contract, and a list of personnel whose pre- and post-doctoral education consisted in part in participation in this project.

  11. Calibration and optimization of proportional counter modules using Garfield

    SciTech Connect

    Chung, Kiwhan; Brockwell, Michael I; Borozdin, Konstantin N; Green, J Andrew; Hogan, Gary E; Makela, Mark F; Mariam, Fesseha G; Morris, Christopher L

    2010-01-01

    Prototypes of radiation detector arrays used for charged-particle radiography require iniliol calibration to correlate the distribution of electron arrival time to the particle track locations. This step is crucial to obtaining the spatial resolution necessary to separate particle tracks traversing the individual proportional counters in the arrays. Our past attempts to use cosmic rays alone for the initial calibration have fallen short of obtaining the desired resolution due to the insufficient cosmic ray flux to provide the necessary number of particle tracks. A theoretical relation between electron drift time and radial drift distance is obtained with Garfield, a CERN gas detector simulation program. This relation is then used as an effective starting point for the initial calibration and results in a shorter calibration period and improved spatial resolution of the detectors.

  12. Optimization of simultaneous tritium–radiocarbon internal gas proportional counting

    SciTech Connect

    Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

    2016-03-01

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium counting efficiency while minimizing radiocarbon beta decay interference.

  13. Optimization of simultaneous tritium-radiocarbon internal gas proportional counting

    NASA Astrophysics Data System (ADS)

    Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

    2016-03-01

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a natural methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium-counting efficiency while minimizing radiocarbon beta-decay interference.

  14. Alpha Backgrounds in the SNO ^3He Proportional Counter Array

    NASA Astrophysics Data System (ADS)

    Stonehill, Laura

    2006-04-01

    The Sudbury Neutrino Observatory (SNO) has recently deployed an array of proportional counters known as Neutral Current Detectors (NCDs) to detect thermalized neutrons via the ^3He(n,p)^3H reaction. The primary physics background to the neutron-capture signal is alpha particle emission from uranium- and thorium-chain decays in the NCD walls. The expected capture rate of neutrons from the neutral-current neutrino reaction on deuterium is three per day and the intrinsic alpha background rate is approximately 250 alphas per day. Fewer than 10% of these alphas fall into the energy range where neutron-capture signals occur, and a substantial number of these can be eliminated by pulse-shape analysis. This talk will focus on measurements of the alpha backgrounds in the NCDs and the extent to which these alphas contaminate the neutron-capture signal region.

  15. The evolution of human and ape hand proportions.

    PubMed

    Almécija, Sergio; Smaers, Jeroen B; Jungers, William L

    2015-07-14

    Human hands are distinguished from apes by possessing longer thumbs relative to fingers. However, this simple ape-human dichotomy fails to provide an adequate framework for testing competing hypotheses of human evolution and for reconstructing the morphology of the last common ancestor (LCA) of humans and chimpanzees. We inspect human and ape hand-length proportions using phylogenetically informed morphometric analyses and test alternative models of evolution along the anthropoid tree of life, including fossils like the plesiomorphic ape Proconsul heseloni and the hominins Ardipithecus ramidus and Australopithecus sediba. Our results reveal high levels of hand disparity among modern hominoids, which are explained by different evolutionary processes: autapomorphic evolution in hylobatids (extreme digital and thumb elongation), convergent adaptation between chimpanzees and orangutans (digital elongation) and comparatively little change in gorillas and hominins. The human (and australopith) high thumb-to-digits ratio required little change since the LCA, and was acquired convergently with other highly dexterous anthropoids.

  16. The evolution of human and ape hand proportions

    PubMed Central

    Almécija, Sergio; Smaers, Jeroen B.; Jungers, William L.

    2015-01-01

    Human hands are distinguished from apes by possessing longer thumbs relative to fingers. However, this simple ape-human dichotomy fails to provide an adequate framework for testing competing hypotheses of human evolution and for reconstructing the morphology of the last common ancestor (LCA) of humans and chimpanzees. We inspect human and ape hand-length proportions using phylogenetically informed morphometric analyses and test alternative models of evolution along the anthropoid tree of life, including fossils like the plesiomorphic ape Proconsul heseloni and the hominins Ardipithecus ramidus and Australopithecus sediba. Our results reveal high levels of hand disparity among modern hominoids, which are explained by different evolutionary processes: autapomorphic evolution in hylobatids (extreme digital and thumb elongation), convergent adaptation between chimpanzees and orangutans (digital elongation) and comparatively little change in gorillas and hominins. The human (and australopith) high thumb-to-digits ratio required little change since the LCA, and was acquired convergently with other highly dexterous anthropoids. PMID:26171589

  17. The consequences of proportional hazards based model selection.

    PubMed

    Campbell, H; Dean, C B

    2014-03-15

    For testing the efficacy of a treatment in a clinical trial with survival data, the Cox proportional hazards (PH) model is the well-accepted, conventional tool. When using this model, one typically proceeds by confirming that the required PH assumption holds true. If the PH assumption fails to hold, there are many options available, proposed as alternatives to the Cox PH model. An important question which arises is whether the potential bias introduced by this sequential model fitting procedure merits concern and, if so, what are effective mechanisms for correction. We investigate by means of simulation study and draw attention to the considerable drawbacks, with regard to power, of a simple resampling technique, the permutation adjustment, a natural recourse for addressing such challenges. We also consider a recently proposed two-stage testing strategy (2008) for ameliorating these effects. Copyright © 2013 John Wiley & Sons, Ltd.

  18. The effect of abnormal cell proportion on specimen classifier performance

    NASA Technical Reports Server (NTRS)

    Castleman, K. R.; White, B. S.

    1981-01-01

    An analysis is presented of the results obtained from a cell classifier which is confronted with an abnormal/normal cell ratio which is different from the ratio assumed in the calibration of the classifier. False negative and false positive error rates are determined in advance for classifier operation, along with the necessary sample size in order to validate the predicted distributions. Changes are demonstrated to happen only regarding the false negative rate, where reductions in the abnormal cell rate below the expected rates would cause totally unreliable data. Substantial overproduction of abnormal cells would be quickly noticeable, while production rates beyond, but close to, the expected rates would only require more extensive sampling. Classifier systems for 10% proportions of abnormal cells are concluded to be possible, but difficulties are present with much lower rates

  19. The effect of abnormal cell proportion on specimen classifier performance

    NASA Technical Reports Server (NTRS)

    Castleman, K. R.; White, B. S.

    1981-01-01

    An analysis is presented of the results obtained from a cell classifier which is confronted with an abnormal/normal cell ratio which is different from the ratio assumed in the calibration of the classifier. False negative and false positive error rates are determined in advance for classifier operation, along with the necessary sample size in order to validate the predicted distributions. Changes are demonstrated to happen only regarding the false negative rate, where reductions in the abnormal cell rate below the expected rates would cause totally unreliable data. Substantial overproduction of abnormal cells would be quickly noticeable, while production rates beyond, but close to, the expected rates would only require more extensive sampling. Classifier systems for 10% proportions of abnormal cells are concluded to be possible, but difficulties are present with much lower rates

  20. A multiwire proportional counter system for high energy astrophysics

    NASA Technical Reports Server (NTRS)

    Lacy, J. L.; Badhwar, G. D.; Deney, C. L.; Golden, R. L.

    1974-01-01

    Resolution tests of multiwire proportional counter delay line readout systems are reported. The system is being developed at NASA/JSC for use in a large balloon borne magnet spectrometer. The system is ultimately intended for use in Space Shuttle missions. Tests of two different types of delay line and associated electronics carried out in minimum ionizing particle beams (accelerator and sea level cosmic ray) are reported. Resolution performance is shown to be strongly dependent on type of gas mixture and in the case of inclined events upon the propagation velocity of the delay line. The resolution performance achieved for magic gas chamber filling (100 um at normal incidence) is far superior to any other state of the art technique capable of being applied to large geometry factor systems.

  1. A Bayesian equivalency test for two independent binomial proportions.

    PubMed

    Kawasaki, Yohei; Shimokawa, Asanao; Yamada, Hiroshi; Miyaoka, Etsuo

    2016-01-01

    In clinical trials, it is often necessary to perform an equivalence study. The equivalence study requires actively denoting equivalence between two different drugs or treatments. Since it is not possible to assert equivalence that is not rejected by a superiority test, statistical methods known as equivalency tests have been suggested. These methods for equivalency tests are based on the frequency framework; however, there are few such methods in the Bayesian framework. Hence, this article proposes a new index that suggests the equivalency of binomial proportions, which is constructed based on the Bayesian framework. In this study, we provide two methods for calculating the index and compare the probabilities that have been calculated by these two calculation methods. Moreover, we apply this index to the results of actual clinical trials to demonstrate the utility of the index.

  2. A multiwire proportional counter system for high energy astrophysics

    NASA Technical Reports Server (NTRS)

    Lacy, J. L.; Badhwar, G. D.; Deney, C. L.; Golden, R. L.

    1974-01-01

    Resolution tests of multiwire proportional counter delay line readout systems are reported. The system is being developed at NASA/JSC for use in a large balloon borne magnet spectrometer. The system is ultimately intended for use in Space Shuttle missions. Tests of two different types of delay line and associated electronics carried out in minimum ionizing particle beams (accelerator and sea level cosmic ray) are reported. Resolution performance is shown to be strongly dependent on type of gas mixture and in the case of inclined events upon the propagation velocity of the delay line. The resolution performance achieved for magic gas chamber filling (100 um at normal incidence) is far superior to any other state of the art technique capable of being applied to large geometry factor systems.

  3. Design of pneumatic proportional flow valve type 5/3

    NASA Astrophysics Data System (ADS)

    Laski, P. A.; Pietrala, D. S.; Zwierzchowski, J.; Czarnogorski, K.

    2017-08-01

    In this paper the 5/3-way pneumatic, proportional flow valve was designed and made. Stepper linear actuator was used to move the spool. The valve is controlled by the controlled based on a AVR microcontroller. Virtual model of the valve was created in CAD. The real element was made based on a standard 5/3-way manually actuated valve with hand lever, which was dismounted and replaced by linear stepper motor. All the elements was mounted in a specially made housing. The controller consists of microcontroller Atmega16, integrated circuit L293D, display, two potentiometers, three LEDs and six buttons. Series of research was also conducted. Simulation research were performed using CFD by the Flow Simulation addition to SolidWorks. During the experiments the valve characteristics of flow and pressure was determined.

  4. Response of a tissue equivalent proportional counter to neutrons

    NASA Technical Reports Server (NTRS)

    Badhwar, G. D.; Robbins, D. E.; Gibbons, F.; Braby, L. A.

    2002-01-01

    The absorbed dose as a function of lineal energy was measured at the CERN-EC Reference-field Facility (CERF) using a 512-channel tissue equivalent proportional counter (TEPC), and neutron dose equivalent response evaluated. Although there are some differences, the measured dose equivalent is in agreement with that measured by the 16-channel HANDI tissue equivalent counter. Comparison of TEPC measurements with those made by a silicon solid-state detector for low linear energy transfer particles produced by the same beam, is presented. The measurements show that about 4% of dose equivalent is delivered by particles heavier than protons generated in the conducting tissue equivalent plastic. c2002 Elsevier Science Ltd. All rights reserved.

  5. Observational evidence for travelling wave modes bearing distance proportional shifts

    NASA Astrophysics Data System (ADS)

    Guruprasad, V.

    2015-06-01

    Discrepancies of range between the Space Surveillance Network radars and the Deep Space Network in tracking the 1998 Earth flyby of NEAR, and between ESA's Doppler and range data in Rosetta's 2009 flyby, reveal a consistent excess delay, or lag, equal to instantaneous one-way travel time in the telemetry signals. These lags readily explain all details of the flyby anomaly, and are shown to be symptoms of chirp d'Alembertian travelling wave solutions, relating to traditional sinusoidal waves by a rotation of the spectral decomposition due to the clock acceleration caused by the Doppler rates during the flybys. The lags thus relate to special relativity, but yield distance proportional shifts like those of cosmology at short range.

  6. Debris and meteoroid proportions deduced from impact crater residue analysis

    NASA Technical Reports Server (NTRS)

    Berthoud, Lucinda; Mandeville, Jean-Claude; Durin, Christian; Borg, Janet

    1995-01-01

    This study is a further investigation of space-exposed samples recovered from the LDEF satellite and the Franco-Russian 'Aragatz' dust collection experiment on the Mir Space Station. Impact craters with diameters ranging from 1 to 900 micron were found on the retrieved samples. Elemental analysis of residues found in the impact craters was carried out using Energy Dispersive X-ray spectrometry (EDX). The analyses show evidence of micrometeoroid and orbital debris origins for the impacts. The proportions of these two components vary according to particle size and experimental position with respect to the leading edge of the spacecraft. On the LDEF leading edge 17 percent of the impacts were apparently caused by micrometeoroids and 11 percent by debris; on the LDEF trailing edge 23 percent of the impacts are apparently caused by micrometeoroids and 4 percent consist of debris particles - mostly larger than 3 micron in diameter - in elliptical orbits around the Earth. For Mir, the analyses indicate that micrometeoroids form 23 percent of impacts and debris 9 percent. However, we note that 60-70 percent of the craters are unidentifiable, so the definitive proportions of natural v. man-made particles are yet to be determined. Experiments carried out using a light gas gun to accelerate glass spheres and fragments demonstrate the influence of particle shape on crater morphology. The experiments also show that it is more difficult to analyze the residues produced by an irregular fragment than those produced by a spherical projectile. If the particle is travelling above a certain velocity, it vaporizes upon impact and no residues are left. Simulation experiments carried out with an electrostatic accelerator indicate that this limit is about 14 km/s for Fe particles impacting Al targets. This chemical analysis cut-off may bias interpretations of the relative populations of meteoroid and orbital debris. Oblique impacts and multiple foil detectors provide a higher likelihood

  7. Debris and meteoroid proportions deduced from impact crater residue analysis

    SciTech Connect

    Berthoud, L.; Mandeville, J.C.; Durin, C.; Borg, J. |

    1995-02-01

    This study is a further investigation of space-exposed samples recovered from the LDEF satellite and the Franco-Russian `Aragatz` dust collection experiment on the Mir Space Station. Impact craters with diameters ranging from 1 to 900 micron were found on the retrieved samples. Elemental analysis of residues found in the impact craters was carried out using Energy Dispersive X-ray spectrometry (EDX). The analyses show evidence of micrometeoroid and orbital debris origins for the impacts. The proportions of these two components vary according to particle size and experimental position with respect to the leading edge of the spacecraft. On the LDEF leading edge 17 percent of the impacts were apparently caused by micrometeoroids and 11 percent by debris; on the LDEF trailing edge 23 percent of the impacts are apparently caused by micrometeoroids and 4 percent consist of debris particles - mostly larger than 3 micron in diameter - in elliptical orbits around the Earth. For Mir, the analyses indicate that micrometeoroids form 23 percent of impacts and debris 9 percent. However, the authors note that 60-70 percent of the craters are unidentifiable, so the definitive proportions of natural vs. man-made particles are yet to be determined. Experiments carried out using a light gas gun to accelerate glass spheres and fragments demonstrate the influence of particle shape on crater morphology. The experiments also show that it is more difficult to analyze the residues produced by an irregular fragment than those produced by a spherical projectile. If the particle is travelling above a certain velocity, it vaporizes upon impact and no residues are left. Simulation experiments carried out with an electrostatic accelerator indicate that this limit is about 14 km/s for Fe particles impacting Al targets. This chemical analysis cut-off may bias interpretations of the relative populations of meteoroid and orbital debris.

  8. Ideal proportions in full face front view, contemporary versus antique.

    PubMed

    Mommaerts, M Y; Moerenhout, B A M M L

    2011-03-01

    To compare the facial proportions of contemporary harmonious faces with those of antiquity, to validate classical canons and to determine new ones useful in orthofacial surgery planning. Contemporary beautiful faces were retrieved from yearly polls of People Magazine and FHM. Selected B/W frontal facial photographs of 31 men and 74 women were ranked by 20 patients who had to undergo orthofacial surgery. The top-15 female faces and the top-10 male faces were analyzed with Scion Image software. The classical facial index, the Bruges facial index, the ratio lower facial height/total facial height and the vertical tri-partite of the lower face were calculated. The same analysis was done on pictures of classical sculptures representing seven goddesses and 12 gods. Harmonious contemporary female faces have a significantly lower classical facial index, indicating that facial height is less or facial width is larger than in male and even than in antique female faces. The Bruges index indicates a similar difference between ideal contemporary female and male faces. The contemporary male has a higher lower face (48%) compared to total facial height than the contemporary female (45%), although this is statistically not significant (P=0.08). The lower facial thirds index remained quite stabile for 2500 years, without gender difference. A good canon for both sexes today is stomion-gnathion being 70% of subnasale-stomion. The average ideal contemporary female face is shorter than the male face, given the fact that interpupillary distance is similar. The Vitruvian thirds in the lower face have to be adjusted to a 30% upper lip, 70% lower lip-chin proportion. The contemporary ideal ratios are suitable to be implemented in an orthofacial planning concept. Copyright © 2010 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  9. Development and evaluation of a water level proportional water sampler

    NASA Astrophysics Data System (ADS)

    Schneider, P.; Lange, A.; Doppler, T.

    2013-12-01

    We developed and adapted a new type of sampler for time-integrated, water level proportional water quality sampling (e.g. nutrients, contaminants and stable isotopes). Our samplers are designed for sampling small to mid-size streams based on the law of Hagen-Poiseuille, where a capillary (or a valve) limits the sampling aliquot by reducing the air flux out of a submersed plastic (HDPE) sampling container. They are good alternatives to battery-operated automated water samplers when working in remote areas, or at streams that are characterized by pronounced daily discharge variations such as glacier streams. We evaluated our samplers against standard automated water samplers (ISCO 2900 and ISCO 6712) during the snowmelt in the Black Forest and the Alps and tested them in remote glacial catchments in Iceland, Switzerland and Kyrgyzstan. The results clearly showed that our samplers are an adequate tool for time-integrated, water level proportional water sampling at remote test sites, as they do not need batteries, are relatively inexpensive, lightweight, and compact. They are well suited for headwater streams - especially when sampling for stable isotopes - as the sampled water is perfectly protected against evaporation. Moreover, our samplers have a reduced risk of icing in cold environments, as they are installed submersed in water, whereas automated samplers (typically installed outside the stream) may get clogged due to icing of hoses. Based on this study, we find these samplers to be an adequate replacement for automated samplers when time-integrated sampling or solute load estimates are the main monitoring tasks.

  10. Sample size calculation for the proportional hazards cure model.

    PubMed

    Wang, Songfeng; Zhang, Jiajia; Lu, Wenbin

    2012-12-20

    In clinical trials with time-to-event endpoints, it is not uncommon to see a significant proportion of patients being cured (or long-term survivors), such as trials for the non-Hodgkins lymphoma disease. The popularly used sample size formula derived under the proportional hazards (PH) model may not be proper to design a survival trial with a cure fraction, because the PH model assumption may be violated. To account for a cure fraction, the PH cure model is widely used in practice, where a PH model is used for survival times of uncured patients and a logistic distribution is used for the probability of patients being cured. In this paper, we develop a sample size formula on the basis of the PH cure model by investigating the asymptotic distributions of the standard weighted log-rank statistics under the null and local alternative hypotheses. The derived sample size formula under the PH cure model is more flexible because it can be used to test the differences in the short-term survival and/or cure fraction. Furthermore, we also investigate as numerical examples the impacts of accrual methods and durations of accrual and follow-up periods on sample size calculation. The results show that ignoring the cure rate in sample size calculation can lead to either underpowered or overpowered studies. We evaluate the performance of the proposed formula by simulation studies and provide an example to illustrate its application with the use of data from a melanoma trial. Copyright © 2012 John Wiley & Sons, Ltd.

  11. Forelimb segment length proportions in extant hominoids and Australopithecus afarensis.

    PubMed

    Drapeau, Michelle S M; Ward, Carol V

    2007-03-01

    Forelimb proportions have been used to infer locomotor adaptation in Australopithecus afarensis. However, little is known about proportions among individual forelimb segments in extant or fossil hominoids. The partial A. afarensis skeleton A.L. 438-1 and the more complete skeleton A.L. 288-1 provide the opportunity to assess relative length of the arm, forearm, wrist, and palm. We compare scaling relationships between pairs of forelimb bones of extant hominoids and A. afarensis, and length of individual forelimb elements to a body size surrogate. Hylobatids, and to a lesser extent orangutans, have the longest forelimb bones relative to size, although the carpus varies little among taxa, perhaps due to functional constraints of the wrist. Pan species are unique in having long metacarpals relative to ulnar length, demonstrating that they probably differ from the common chimp-human ancestor, and also that developmental mechanisms can be altered to results in differential growth of individual forelimb segments. A. afarensis has no forelimb bones that are significantly longer than those of humans for its size. It falls within the range of variation seen in modern humans for all comparisons relative to size, but appears to differ from the typical human brachial index due to a slightly shorter humerus and/or slightly longer ulna. It has short metacarpals like humans only among hominoids. Thus, while Pan may have elongated its metacarpus relative to ulnar length, A. afarensis may have reduced the length of its metacarpals and possibly its humerus relative to body size from the primitive condition.

  12. Outcome of total hip arthroplasty in small-proportioned patients.

    PubMed

    Rahimtoola, Z O; Finger, S; Imrie, S; Goodman, S B

    2000-01-01

    In a prospective, consecutive series, 41 total hip arthroplasties were performed in 27 small-proportioned patients with small femoral dimensions. The 17 female and 10 male patients averaged 23.6 years (range, 14-47 years), and the mean height and weight were 157 cm (range, 132-183 cm) and 53.5 kg (range, 36-84 kg). The most common preoperative diagnosis was juvenile rheumatoid arthritis in 18 patients (28 hips). Most patients were severely disabled in their daily activity, and 68% of the patients were classified as Charnley functional class C. The femoral implants consisted primarily of the proximally porous-coated miniature Anatomic Medullary Locking femoral component (AML/CDH, Depuy, Warsaw, IN) in 33 hips in 22 patients (average stem diameter, 9.5 mm; range, 8-12.0 mm). A porous ingrowth acetabular cup fixed with screws was used in all procedures. At an average follow-up of 51 months, Harris Hip Scores improved significantly from 34 points (range, 0-65 points) preoperatively to 85 points (range, 33-100 points) after arthroplasty. There were no intraoperative complications. There was 1 revision because of femoral implant loosening. Three cementless femoral components showed evidence of nonprogressive subsidence. One patient had significant bilateral acetabular component polyethylene wear and underwent revision. All other femoral and acetabular components were radiographically stable. The relief of pain and improvement of function were dramatic. The miniature AML/CDH femoral component, combined with an uncemented acetabular cup, provides a promising, off-the-shelf alternative in small-proportioned patients.

  13. An active vibration isolation system using adaptive proportional control method

    NASA Astrophysics Data System (ADS)

    Liu, Yun-Hui; Hsieh, Hung-En; Wu, Wei-Hao

    2014-03-01

    This paper is concerned with a six-degree-of-freedom active vibration isolation system using voice coil actuators with absolute velocity feedback control for highly sensitive measurement equipment, e.g. atomic force microscopes, suffering from building vibration. The main differences between this type of system and traditional isolator, is that there are no isolator resonance. The absolute vibration velocity signal acquired from an accelerator and being processed through an integrator is input to the controller as a feedback signal, and the controller output signal drives the voice coil actuator to produce a sky-hook damper force. In practice, the phase response of integrator at low frequency such as 2~6 Hz deviate from the 90 degree which is the exact phase difference between the vibration velocity and acceleration. Therefore, an adaptive filter is used to compensate the phase error in this paper. An analysis of this active vibration isolation system is presented, and model predictions are compared to experimental results. The results show that the proposed method significantly reduces transmissibility at resonance without the penalty of increased transmissibility at higher frequencies.

  14. The effect of enslaving on perception of finger forces.

    PubMed

    Li, Sheng; Leonard, Charles T

    2006-07-01

    The primary purpose was to examine the effect of enslaving on finger force perception during isometric finger force production using an ipsilateral force-matching paradigm. Fourteen subjects were instructed to produce varying levels of reference forces [10, 20, 30, and 40% maximal voluntary contraction (MVC)] force using one finger (index, I or little, L) and to reproduce these forces using the same finger (homo-finger tasks, I/I and L/L) or a different finger (hetero-finger tasks, I/L and L/I). Forces of all fingers were recorded. During homo-finger tasks, no differences were found in force magnitude or relative level of force (expressed as a proportion of MVC). The index finger matching force magnitudes were greater than the little finger reference force magnitudes, with significantly lower levels of relative force during L/I tasks; while the little finger matching forces underestimated the index finger reference forces with significantly higher levels of relative force during I/L tasks. The difference in the matching and reference forces by the instructed finger(s), i.e., matching error, was larger in hetero-finger tasks than in homo-finger tasks, particularly at high reference force levels (30, 40% MVC). When forces of all fingers were considered, enslaving (uninstructed finger forces) significantly minimized matching errors of the total force during both I/L and L/I hetero-finger tasks, especially at high reference force levels. Our results show that there is a tendency to match the absolute magnitude of the total force during ipsilateral finger force-matching tasks. This tendency is likely related to enslaving effects. Our results provide evidence that all (instructed and uninstructed) finger forces are sensed, thus resulting in perception of the absolute magnitude of total finger force.

  15. Active AFO with ankle joint brake friction control using force observer.

    PubMed

    Yoshizawa, Nobuyuki

    2012-01-01

    Optimum friction control of the ankle joint brake is essential for realizing a stable gait when wearing an active ankle foot orthosis (AFO). An optimum friction control system using a force observer is designed and simulated. The brake friction is controlled in proportion to the observed human force of the lower limb without using force sensors. The simulated results show that the force observer performs well. The force-controlled orthosis is robust and practical because it uses no force sensors.

  16. Improved yield of minimal proportional sample volume platelet bacterial culture.

    PubMed

    Kamel, Hany; Townsend, Mary; Bravo, Marjorie; Vassallo, Ralph R

    2017-10-01

    Reports of septic transfusion reactions (STRs) after transfusion of culture-negative platelets (PLTs) justify more effective prevention strategies. Pathogen reduction technologies or performance of additional point-of-issue testing are proposed strategies to enhance safety through Day 5 of storage. Trima leukoreduced apheresis PLTs (APs) were collected during two study periods (45 and 31 months) using standard procedures, with target settings adjusted during the second period to maintain split rate after increased culture volume. Primary testing for bacterial contamination was performed using BacT/ALERT 3D with sampling from the mother bag 24 to 36 hours after collection. Two culture approaches were compared: in Period A, an 8-mL sample in one aerobic culture bottle (CB), and in Period B a minimal proportional sample volume (PSV) of at least 3.8% of mother bag volume into one to three aerobic CBs (7-10 mL per bottle). In Periods A and B, 188,389 and 159,098 AP collections were tested, respectively. The true-positive (TP) rate in Period A was 0.90 per 10,000 collections and in Period B was 1.83 per 10,000 (p < 0.05). In Period B, 12 of 29 (41%) TP results had discrepant CB results (DCBRs; at least one of multiple bottles without growth). The false-positive rate in Period B, 15.05 per 10,000 collections, was significantly higher than that of Period A, 3.66 per 10,000. One contaminated collection resulting in STR(s) was reported in each study period. Implementation of PSV was operationally successful and did not impact the AP split rate. Proportional sample volume improved the sensitivity of primary testing and identified collections that could have escaped detection had only a single bottle with 8- to 10-mL volume been used. PSV may represent another approach to enhanced PLT safety for 5-day storage without a requirement for secondary testing. © 2017 AABB.

  17. Pharmacokinetics and dose proportionality of ketoconazole in normal volunteers.

    PubMed Central

    Huang, Y C; Colaizzi, J L; Bierman, R H; Woestenborghs, R; Heykants, J

    1986-01-01

    Ketoconazole is an orally effective, broad-spectrum, systemic antifungal agent. The pharmacokinetics and bioavailability of ketoconazole given as a 200-mg single dose in a tablet, suspension, or solution were studied in 24 fasting healthy males by using a crossover design. Levels of ketoconazole in plasma were determined for up to 48 h by a sensitive reverse-phase high-performance liquid chromatography method. The absorption of ketoconazole was rapid, with mean maximum concentrations of the drug in plasma of 4.2, 5.0, and 6.2 micrograms/ml attained at 1.7, 1.2, and 1.0 h, respectively, after administration of the tablet, suspension, and solution, respectively. The mean distribution and elimination half-life values were 1.5 to 1.7 and 7.5 to 7.9 h, respectively. The mean oral clearance of the solution dose was 209 (+/- 82.9 [standard deviation]) ml/min, and the mean apparent volume of distribution was 88.31 (+/- 68.72) liters. The relative bioavailabilities for the tablet and suspension were 81.2 (+/- 33.5) and 89.0 (+/- 23.1)%, respectively, of that of the solution. The data indicated the bioequivalence of the tablet to the suspension and of the suspension of the solution. Dose proportionality of ketoconazole was also studied in 12 volunteers after they received solution doses of 200, 400, and 800 mg. Linear correlations between the dose and the maximum concentration of the drug in plasma, the time to the maximum concentration, and the area under the concentration-time curve were observed. However, the increase in the area under the curve was more than proportional to the dose given. The levels in plasma seemed to decay at a lower rate after 400- and 800-mg doses. The mean oral clearance decreased from 244.9 to 123.6 and 80.0 ml/min, respectively, as the dose increased from 200 to 400 and 800 mg. The apparent dose-dependent kinetics may have been due to the presystemic elimination and capacity-limited hepatic metabolism which become saturated at higher doses. PMID

  18. High proportion of cactus species threatened with extinction.

    PubMed

    Goettsch, Bárbara; Hilton-Taylor, Craig; Cruz-Piñón, Gabriela; Duffy, James P; Frances, Anne; Hernández, Héctor M; Inger, Richard; Pollock, Caroline; Schipper, Jan; Superina, Mariella; Taylor, Nigel P; Tognelli, Marcelo; Abba, Agustín M; Arias, Salvador; Arreola-Nava, Hilda J; Baker, Marc A; Bárcenas, Rolando T; Barrios, Duniel; Braun, Pierre; Butterworth, Charles A; Búrquez, Alberto; Caceres, Fátima; Chazaro-Basañez, Miguel; Corral-Díaz, Rafael; Del Valle Perea, Mario; Demaio, Pablo H; Duarte de Barros, Williams A; Durán, Rafael; Yancas, Luis Faúndez; Felger, Richard S; Fitz-Maurice, Betty; Fitz-Maurice, Walter A; Gann, George; Gómez-Hinostrosa, Carlos; Gonzales-Torres, Luis R; Patrick Griffith, M; Guerrero, Pablo C; Hammel, Barry; Heil, Kenneth D; Hernández-Oria, José Guadalupe; Hoffmann, Michael; Ishihara, Mario Ishiki; Kiesling, Roberto; Larocca, João; León-de la Luz, José Luis; Loaiza S, Christian R; Lowry, Martin; Machado, Marlon C; Majure, Lucas C; Ávalos, José Guadalupe Martínez; Martorell, Carlos; Maschinski, Joyce; Méndez, Eduardo; Mittermeier, Russell A; Nassar, Jafet M; Negrón-Ortiz, Vivian; Oakley, Luis J; Ortega-Baes, Pablo; Ferreira, Ana Beatriz Pin; Pinkava, Donald J; Porter, J Mark; Puente-Martinez, Raul; Gamarra, José Roque; Pérez, Patricio Saldivia; Martínez, Emiliano Sánchez; Smith, Martin; Manuel Sotomayor M Del C, J; Stuart, Simon N; Muñoz, José Luis Tapia; Terrazas, Teresa; Terry, Martin; Trevisson, Marcelo; Valverde, Teresa; Van Devender, Thomas R; Véliz-Pérez, Mario Esteban; Walter, Helmut E; Wyatt, Sarah A; Zappi, Daniela; Alejandro Zavala-Hurtado, J; Gaston, Kevin J

    2015-10-05

    A high proportion of plant species is predicted to be threatened with extinction in the near future. However, the threat status of only a small number has been evaluated compared with key animal groups, rendering the magnitude and nature of the risks plants face unclear. Here we report the results of a global species assessment for the largest plant taxon evaluated to date under the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, the iconic Cactaceae (cacti). We show that cacti are among the most threatened taxonomic groups assessed to date, with 31% of the 1,478 evaluated species threatened, demonstrating the high anthropogenic pressures on biodiversity in arid lands. The distribution of threatened species and the predominant threatening processes and drivers are different to those described for other taxa. The most significant threat processes comprise land conversion to agriculture and aquaculture, collection as biological resources, and residential and commercial development. The dominant drivers of extinction risk are the unscrupulous collection of live plants and seeds for horticultural trade and private ornamental collections, smallholder livestock ranching and smallholder annual agriculture. Our findings demonstrate that global species assessments are readily achievable for major groups of plants with relatively moderate resources, and highlight different conservation priorities and actions to those derived from species assessments of key animal groups.

  19. Proportion of Rh phenotypes in voluntary blood donors

    PubMed Central

    Sarkar, R.S.; Philip, Joseph; Mallhi, R.S.; Yadav, Pramod

    2013-01-01

    Background The Rh system is the major blood group system besides ABO system. Even after proper blood grouping and cross matching there is a possibility of alloimmunization and antibody production in the recipients against the Rh or minor blood group antigens like Kell, MNSs, Duffy etc. Keeping in view the heavy financial burden of complete phenotyping of blood; the determination of only Rh phenotypes can play a major role in preventing alloimmunization and adverse events in multitransfusion cases. To determine the proportion of Rh phenotypes in voluntary blood donors with a view to generate blood bank data for constitution of panel of blood donors for multipurpose utilities. Method Identification of Rhesus factors (Rh) was done by the antigen antibody agglutination test by the test tube method on 10,133 healthy voluntary donors. Results The phenotypic frequencies of Rh blood groups in the studied population were D-92.25%, C-87.55%, E-26.55%, c-51.06% and e-98.42%. Thus ‘e’ was the most common and E was the least common of all the Rh types. Phenotypically DCCee group was the most common phenotype and dccee was least common type. Conclusion Determination of Rh phenotypes can play a major role in preventing alloimmunization and avoiding adverse events in multitransfusion cases. PMID:24600138

  20. A vertex trigger based on cylindrical multiwire proportional chambers

    NASA Astrophysics Data System (ADS)

    Becker, J.; Bösiger, K.; Lindfeld, L.; Müller, K.; Robmann, P.; Schmitt, S.; Schmitz, C.; Steiner, S.; Straumann, U.; Szeker, K.; Truöl, P.; Urban, M.; Vollhardt, A.; Werner, N.; Baumeister, D.; Löchner, S.; Hildebrandt, M.

    2008-02-01

    This article describes the technical implementation and the performance of the z-vertex trigger (CIP2k), which is part of the H1-experiment at HERA. The HERA storage ring and collider was designed to investigate electron (and positron) proton scattering at a center-of-mass energy of 320 GeV. To improve the sensitivity for detecting non-standard model physics and other high momentum transfer phenomena, the HERA ring has been ungraded between 2000 and 2003 to increase the specific luminosity for the experiments. In order to cope with the increased event and background rate the experiments were upgraded, too. The CIP2k trigger system is based on a set of five cylindrical multiwire proportional chambers with cathode pad readout, and allows to distinguish between events induced by beam background and ep-interactions at the first trigger stage. The trigger decision is calculated dead-time free with a latency of 1.5 μs in parallel to the beam clock at 10.4 MHz. The trigger-logic is realized in large field programmable gate arrays (FPGA) using the hardware description language Verilog. The system is operational since October 2003. It suppresses background events with high efficiency and provides event timing information, as designed.

  1. Results from an iron-proportional tube calorimeter prototype.

    SciTech Connect

    Schoessow, P.

    1998-02-03

    We have studied the energy resolution of a prototype gas tracking calorimeter in a test beam at Fermilab as part of the detector development program for the MINOS long baseline neutrino oscillation experiment. The calorimeter consisted of 25 layers of 1.5 inch thick steel plates interleaved with planes of aluminum proportional tubes. The tube cells are square, with 0.9 cm edges and open tops. Cathode strips were used for read out transverse to the wire cells. The tubes operated with a nonflammable gas mixture of 88% CO{sub 2}, 9.5% isobutane and 2.5% argon which gave an operating range of >500 V (limited by the electronics). We read out the wire signals on the tubes and in some configurations the cathode stripe as well. We studied positrons, pions and muons over a momentum range of 2.5-30 GeV/c and achieved energy resolutions of about 40%/{radical}E for EM and 71%/{radical}E for hadronic showers.

  2. Estimating False Discovery Proportion Under Arbitrary Covariance Dependence*

    PubMed Central

    Fan, Jianqing; Han, Xu; Gu, Weijie

    2012-01-01

    Multiple hypothesis testing is a fundamental problem in high dimensional inference, with wide applications in many scientific fields. In genome-wide association studies, tens of thousands of tests are performed simultaneously to find if any SNPs are associated with some traits and those tests are correlated. When test statistics are correlated, false discovery control becomes very challenging under arbitrary dependence. In the current paper, we propose a novel method based on principal factor approximation, which successfully subtracts the common dependence and weakens significantly the correlation structure, to deal with an arbitrary dependence structure. We derive an approximate expression for false discovery proportion (FDP) in large scale multiple testing when a common threshold is used and provide a consistent estimate of realized FDP. This result has important applications in controlling FDR and FDP. Our estimate of realized FDP compares favorably with Efron (2007)’s approach, as demonstrated in the simulated examples. Our approach is further illustrated by some real data applications. We also propose a dependence-adjusted procedure, which is more powerful than the fixed threshold procedure. PMID:24729644

  3. Proportion of Rh phenotypes in voluntary blood donors.

    PubMed

    Sarkar, R S; Philip, Joseph; Mallhi, R S; Yadav, Pramod

    2013-10-01

    The Rh system is the major blood group system besides ABO system. Even after proper blood grouping and cross matching there is a possibility of alloimmunization and antibody production in the recipients against the Rh or minor blood group antigens like Kell, MNSs, Duffy etc. Keeping in view the heavy financial burden of complete phenotyping of blood; the determination of only Rh phenotypes can play a major role in preventing alloimmunization and adverse events in multitransfusion cases. To determine the proportion of Rh phenotypes in voluntary blood donors with a view to generate blood bank data for constitution of panel of blood donors for multipurpose utilities. Identification of Rhesus factors (Rh) was done by the antigen antibody agglutination test by the test tube method on 10,133 healthy voluntary donors. The phenotypic frequencies of Rh blood groups in the studied population were D-92.25%, C-87.55%, E-26.55%, c-51.06% and e-98.42%. Thus 'e' was the most common and E was the least common of all the Rh types. Phenotypically DCCee group was the most common phenotype and dccee was least common type. Determination of Rh phenotypes can play a major role in preventing alloimmunization and avoiding adverse events in multitransfusion cases.

  4. Sampling of sparse species with probability proportional to prediction.

    PubMed

    Ringvall, Anna; Kruys, Nicholas

    2005-05-01

    In this article, a 3P sampling (Probability Proportional to Prediction) approach is presented for surveying sparse species connected to certain types of substrates. The method uses the surveyor's judgement of the probability of finding the species on a substrate as the base for selection of substrates for species inventories. The method is presented together with estimators, variances and variance estimators. The method is first presented for sampling based on all substrates in a study area and then as a subsampling technique in a two-stage design in which plots or strips are selected in a first stage. The presented approach was evaluated as a subsampling technique in a strip survey of calicioid lichen species associated with coarse broadleaf trees. In comparison with a simple random subsampling without replacement, 3P subsampling was in one study area found to be an improvement with 30-55% in terms of standard errors. The improvement was more modest in the other study area, only between 10-16%. The strip survey with 3P subsampling was more cost-efficient than a strip survey without subsampling except in one case. Based on the results in the test, 3P sampling seems to have a potential for sampling sparse species.

  5. Novel definition and algorithm for chaining fragments with proportional overlaps.

    PubMed

    Uricaru, Raluca; Mancheron, Alban; Rivals, Eric

    2011-09-01

    Chaining fragments is a crucial step in genome alignment. Existing chaining algorithms compute a maximum weighted chain with no overlaps allowed between adjacent fragments. In practice, using local alignments as fragments, instead of Maximal Exact Matches (MEMs), generates frequent overlaps between fragments, due to combinatorial reasons and biological factors, i.e., variable tandem repeat structures that differ in number of copies between genomic sequences. In this article, in order to raise this limitation, we formulate a novel definition of a chain, allowing overlaps proportional to the fragments lengths, and exhibit an efficient algorithm for computing such a maximum weighted chain. We tested our algorithm on a dataset composed of 694 genome pairs and accounted for significant improvements in terms of coverage, while keeping the running times below reasonable limits. Moreover, experiments with different ratios of allowed overlaps showed the robustness of the chains with respect to these ratios. Our algorithm is implemented in a tool called OverlapChainer (OC), which is available upon request to the authors.

  6. One-step quantitative cortisol dipstick with proportional reading.

    PubMed

    Leung, Wingman; Chan, Puiyee; Bosgoed, Freddy; Lehmann, Karin; Renneberg, Ilka; Lehmann, Matthias; Renneberg, Reinhard

    2003-10-01

    Rapid quantitative immuno-detection of haptens by the lateral flow assay without "typical" competitive inhibition results is studied. In the present study, we describe an immuno-threshold-based assay for the quantification of cortisol. It gives a signal which is directly proportional to the cortisol concentration in plasma samples with a performance time of only 5 min. This technique provides a practical calibration curve with detection limit of 3.5 ng/ml. The precision of the assay is 6% (intra-assay coefficient of variation, CV) and 10% (inter-assay CV). Cross-reactivity with related steroids is acceptably low: corticosterone (3.38%), cortisone (2.08%), deoxycorticosterone (2.00%), 17alpha-hydroxyprogesterone (0.39%), and progesterone (0.05%). Furthermore, the test strips show the advantages of long storage time and high stability that allow mass production and preparation of large batches. A one-step cortisol whole blood test derived from this plasma lateral flow assay has then been performed. It is a rapid chromatographic immunoassay designed for quantitative determination of cortisol in whole blood samples. It requires no sample pretreatment and gives result within 15 min. In principle, with this rapid and sensitive immunoassay, the immuno-test strips can be employed for detecting all low-molecular-weight haptens. It may also be a useful and convenient dipstick format for drug detection.

  7. Facial approximation: evaluation of dental and facial proportions with height.

    PubMed

    Esan, T A; Oziegbe, O E; Onapokya, H O

    2012-03-01

    Fabrication of complete dentures requires the use of certain guidelines which are placed on the bite blocks to assist the clinician to have the maxillary anterior teeth restored to optimal dento-labial relations, in harmony with the overall facial appearance. To explore if any relationship exists between dental and facial proportions as well as the height of the individuals. Two hundred and four dental students of the Obafemi Awolowo University volunteered to participated in the study. The lower facial height, inter incisal, inter canine, and intercommisure distances, as well as the height of the participants were measured. The data were imputed, analyzed, and reported as simple frequency, means and standard deviations using the SPSS vs 11. Statistical significance was inferred at p<0.05. The mean values of all the parameters measured were significantly higher in males than females. None of the mean values measured were coincident. However, a significant correlation exists between intercanine and interincisal distances(r=0.8) while a weak but significant negative correlation exists between the intercanine distance and the difference of the intercommisural and intercanine distances (r=-0.4) The study showed no relationship between intercanine distance, interincisal distance, lower facial height, and the height of the participants with the intercommissural distance. Hence, intercommissural distance may not be used in marking canine line during bite registration procedure. At best, 1.75-2.45 cm should be subtracted from the intercommissural distance to determine the intercanine distance.

  8. Proportion of antidepressants prescribed without a psychiatric diagnosis is growing.

    PubMed

    Mojtabai, Ramin; Olfson, Mark

    2011-08-01

    Over the past two decades, the use of antidepressant medications has grown to the point that they are now the third most commonly prescribed class of medications in the United States. Much of this growth has been driven by a substantial increase in antidepressant prescriptions by nonpsychiatrist providers without an accompanying psychiatric diagnosis. Our analysis found that between 1996 and 2007, the proportion of visits at which antidepressants were prescribed but no psychiatric diagnoses were noted increased from 59.5 percent to 72.7 percent. These results do not clearly indicate a rise in inappropriate antidepressant use, but they highlight the need to gain a deeper understanding of the factors driving this national trend and to develop effective policy responses. To the extent that antidepressants are being prescribed for uses not supported by clinical evidence, there may be a need to improve providers' prescribing practices, revamp drug formularies, or vigorously pursue implementation of broad reforms of the health care system that will increase communication between primary care providers and mental health specialists.

  9. Substantial proportion of global streamflow less than three months old

    NASA Astrophysics Data System (ADS)

    Jasechko, Scott; Kirchner, James W.; Welker, Jeffrey M.; McDonnell, Jeffrey J.

    2016-02-01

    Biogeochemical cycles, contaminant transport and chemical weathering are regulated by the speed at which precipitation travels through landscapes and reaches streams. Streamflow is a mixture of young and old precipitation, but the global proportions of these young and old components are not known. Here we analyse seasonal cycles of oxygen isotope ratios in rain, snow and streamflow compiled from 254 watersheds around the world, and calculate the fraction of streamflow that is derived from precipitation that fell within the past two or three months. This young streamflow accounts for about a third of global river discharge, and comprises at least 5% of discharge in about 90% of the catchments we investigated. We conclude that, although typical catchments have mean transit times of years or even decades, they nonetheless can rapidly transmit substantial fractions of soluble contaminant inputs to streams. Young streamflow is less prevalent in steeper landscapes, which suggests they are characterized by deeper vertical infiltration. Because young streamflow is derived from less than 0.1% of global groundwater storage, we conclude that this thin veneer of aquifer storage will have a disproportionate influence on stream water quality.

  10. The proportion of cancer attributable to occupational exposures

    PubMed Central

    Purdue, Mark P.; Hutchings, Sally J.; Rushton, Lesley; Silverman, Debra T.

    2015-01-01

    Purpose To review the literature on the estimation of the population attributable fraction (PAF) of cancer due to occupational exposures and to describe challenges in the estimation of this metric. To help illustrate the inherent challenges, we also estimate PAFs for selected cancers diagnosed in the United States in 2010 attributable to work as a painter (causally associated with bladder and lung cancer) and shiftwork (possibly associated with breast cancer). Methods We reviewed and summarized previous reports providing quantitative estimates of PAF for total cancer due to occupational exposures. We calculated PAF estimates for painters and shiftwork using methodology from a detailed investigation of the occupational cancer burden in Great Britain, with adaptations made for the U.S. population. Results The estimated occupation-attributable fraction for total cancer generally ranged between 2% and 8% (men, 3-14%; women, 1-2%) based on previous reports. We calculated that employment as a painter accounted for a very small proportion of cancers of the bladder and lung diagnosed in the United States in 2010, with PAFs of 0.5% for each site. In contrast, our calculations suggest that the potential impact of shiftwork on breast cancer (if causal) could be substantial, with a PAF of 5.7%, translating to 11,777 attributable breast cancers. Conclusions Continued efforts to estimate the occupational cancer burden will be important as scientific evidence and economic trends evolve. Such projects should consider the challenges involved in PAF estimation, which we summarize in this report. PMID:25487971

  11. Proportion of recovered duck bands that are reported

    USGS Publications Warehouse

    Martinson, R.K.

    1966-01-01

    Band-reporting rates (the proportion of duck bands recovered by hunters that are actually reported to the Bird Banding Laboratory) appear to have decreased between the late 1950's and early 1960's. About one-half the banded ducks bagged during the 1958-59 and 1959-60 hunting seasons were reported-a rate similar to those recorded in other studies conducted during the early and mid-1950's. Band-reporting rates were lower for the 1962-63 and 1962-64 hunting seasons; less than one-third of the banded ducks bagged were reported. This decrease in band-reporting rates was concurrent with significant changes in duck hunting regulations, the volume of duck banding, and the method used to relay information to the person who reports a band. Band-reporting rates differed for various species of ducks. In general, band-reporting rates were high on canvasbacks (Aythya valisineria), redheads (A. americana), and pintails Anas acuta) and low for teals (Anas discors and A. carolinensis).

  12. High efficiency proportional neutron detector with solid liner internal structures

    DOEpatents

    Kisner, Roger Allen; Holcomb, David Eugene; Brown, Gilbert M.

    2014-08-05

    A tube-style neutron detector, a panel-style neutron detector incorporating a plurality of tube-style neutron detectors, and a panel-style neutron detector including a plurality of anode wires are provided. A plurality of channels is provided in a neutron detector such that each channel has an inner surface of a coating layer including a neutron-absorbing material. A wire anode is provided at end of each channel so that electrons generated by a charged daughter particle generated by a neutron are collected to detect a neutron-matter interaction. Moderator units can be incorporated into a neutron detector to provide improved detection efficiencies and/or to determine neutron energy spectrum. Gas-based proportional response from the neutron detectors can be employed for special nuclear material (SNM) detection. This neutron detector can provide similar performance to .sup.3He-based detectors without requiring .sup.3He and without containing toxic, flammable, or high-pressure materials.

  13. A neural network theory of proportional analogy-making.

    PubMed

    Jani, N G; Levine, D S

    2000-03-01

    A neural network model that can simulate the learning of some simple proportional analogies is presented. These analogies include, for example, (a) red-square:red-circle :: yellow-square:?, (b) apple:red :: banana: ?, (c) a:b :: c:?. Underlying the development of this network is a theory for how the brain learns the nature of association between pairs of concepts. Traditional Hebbian learning of associations is necessary for this process but not sufficient. This is because it simply says, for example, that the concepts "apple" and "red" have been associated, but says nothing about the nature of this relationship. The types of context-dependent interlevel connections in the network suggest a semilocal type of learning that in some manner involves association among more than two nodes or neurons at once. Such connections have been called synaptic triads, and related to potential cell responses in the prefrontal cortex. Some additional types of connections are suggested by the problem of modeling analogies. These types of connections have not yet been verified by brain imaging, but the work herein suggests that they may occur and, possibly, be made and broken quickly in the course of working memory encoding. These working memory connections are referred to as differential, delayed and anti-Hebbian connections. In these connections, one can learn transitions such as "keep red the same"; "change red to yellow"; "turn off red"; "turn on yellow," and so forth. Also, included in the network is a kind of weight transport so that, for example, red to red can be transported to a different instance of color, such as yellow to yellow. The network instantiation developed here, based on common connectionist building blocks such as associative learning, competition, and adaptive resonance, along with additional principles suggested by analogy data, is a step toward a theory of interactions among several brain areas to develop and learn meaningful relationships between concepts.

  14. Compact multiwire proportional counters for the detection of fission fragments

    SciTech Connect

    Jhingan, Akhil; Sugathan, P.; Golda, K. S.; Singh, R. P.; Varughese, T.; Singh, Hardev; Behera, B. R.; Mandal, S. K.

    2009-12-15

    Two large area multistep position sensitive (two dimensional) multiwire proportional counters have been developed for experiments involving study of fission dynamics using general purpose scattering chamber facility at IUAC. Both detectors have an active area of 20x10 cm{sup 2} and provide position signals in horizontal (X) and vertical (Y) planes, timing signal for time of flight measurements and energy signal giving the differential energy loss in the active volume. The design features are optimized for the detection of low energy heavy ions at very low gas pressures. Special care was taken in setting up the readout electronics, constant fraction discriminators for position signals in particular, to get optimum position and timing resolutions along with high count rate handling capability of low energy heavy ions. A custom made charge sensitive preamplifier, having lower gain and shorter decay time, has been developed for extracting the differential energy loss signal. The position and time resolutions of the detectors were determined to be 1.1 mm full width at half maximum (FWHM) and 1.7 ns FWHM, respectively. The detector could handle heavy ion count rates exceeding 20 kHz without any breakdown. Time of flight signal in combination with differential energy loss signal gives a clean separation of fission fragments from projectile and target like particles. The timing and position signals of the detectors are used for fission coincidence measurements and subsequent extraction of their mass, angular, and total kinetic energy distributions. This article describes systematic study of these fission counters in terms of efficiency, time resolution, count rate handling capability, position resolution, and the readout electronics. The detector has been operated with both five electrode geometry and four electrode geometry, and a comparison has been made in their performances.

  15. Measurement of aesthetic proportions in the profile view of Koreans.

    PubMed

    Wang, Jong Hwan; Jang, Yong Ju; Park, Soo-Kyung; Lee, Bong-Jae

    2009-02-01

    We have evaluated the usefulness of direct soft tissue measurements in profile photographs for determining the nasal proportions and angles of young Korean individuals and those of rhinoplasty patients, and we compared these findings with existing norms of Caucasian populations. We retrospectively compared preoperative profile measurements of nasal length, nasal tip projection, dorsal height, radix height, nasolabial angle, and nasofrontal angle in 123 patients who underwent rhinoplasty, with measurements in 21 young Korean adults. Rhinoplasty patients were grouped by preoperative diagnosis as deviated nose without saddle or hump, saddle nose, hump nose, and low radix. The young Koreans had a nasal length to nasal tip projection to dorsal height to radix height ratio of 2:0.97:0.61:0.28. Dorsal height differed significantly among groups of rhinoplasty patients. Those with low radix had the lowest dorsal and radix height, whereas those with saddle nose had the smallest nasal tip projection. The average nasolabial and nasofrontal angles were 78.5 degrees and 82.7 degrees, respectively, in young male Koreans and 126.0 degrees and 133.6 degrees, respectively, in young female Koreans. In the deviated nose group, all parameters except for nasofrontal angle were significantly changed after rhinoplasty. In the saddle nose group, nasal tip projection and dorsal height were significantly increased, whereas, in the hump nose group, nasal tip projection and nasolabial angle were significantly altered. Direct soft tissue measurement on profile photographs is useful for assessing nasal characteristics and postrhinoplasty outcomes. Compared with Caucasians, young Koreans had relatively lower dorsum and radix and more acute nasolabial angle, but similar nasofrontal angle.

  16. Proportioning and performance evaluation of self-consolidating concrete

    NASA Astrophysics Data System (ADS)

    Wang, Xuhao

    A well-proportioned self-consolidating concrete (SCC) mixture can be achieved by controlling the aggregate system, paste quality, and paste quantity. The work presented in this dissertation involves an effort to study and improve particle packing of the concrete system and reduce the paste quantity while maintaining concrete quality and performance. This dissertation is composed of four papers resulting from the study: (1) Assessing Particle Packing Based Self-Consolidating Concrete Mix Design; (2) Using Paste-To-Voids Volume Ratio to Evaluate the Performance of Self-Consolidating Concrete Mixtures; (3) Image Analysis Applications on Assessing Static Stability and Flowability of Self-Consolidating Concrete, and (4) Using Ultrasonic Wave Propagation to Monitor Stiffening Process of Self-Consolidating Concrete. Tests were conducted on a large matrix of SCC mixtures that were designed for cast-in-place bridge construction. The mixtures were made with different aggregate types, sizes, and different cementitious materials. In Paper 1, a modified particle-packing based mix design method, originally proposed by Brouwers (2005), was applied to the design of self-consolidating concrete (SCC) mixs. Using this method, a large matrix of SCC mixes was designed to have a particle distribution modulus (q) ranging from 0.23 to 0.29. Fresh properties (such as flowability, passing ability, segregation resistance, yield stress, viscosity, set time and formwork pressure) and hardened properties (such as compressive strength, surface resistance, shrinkage, and air structure) of these concrete mixes were experimentally evaluated. In Paper 2, a concept that is based on paste-to-voids volume ratio (Vpaste/Vvoids) was employed to assess the performance of SCC mixtures. The relationship between excess paste theory and Vpaste/Vvoids was investigated. The workability, flow properties, compressive strength, shrinkage, and surface resistivity of SCC mixtures were determined at various ages

  17. Archimedes force on Casimir apparatus

    NASA Astrophysics Data System (ADS)

    Shevchenko, Vladimir; Shevrin, Efim

    2016-08-01

    This paper addresses a problem of Casimir apparatus in dense medium, put in weak gravitational field. The falling of the apparatus has to be governed by the equivalence principle with proper account for contributions to the weight of the apparatus from its material part and from distorted quantum fields. We discuss general expression for the corresponding force in metric with cylindrical symmetry. By way of example, we compute explicit expression for Archimedes force, acting on the Casimir apparatus of finite size, immersed into thermal bath of free scalar field. It is shown that besides universal term, proportional to the volume of the apparatus, there are non-universal quantum corrections, depending on the boundary conditions.

  18. Archimedes force on Casimir apparatus

    NASA Astrophysics Data System (ADS)

    Shevchenko, V.; Shevrin, E.

    2016-11-01

    The talk addresses a problem of Casimir apparatus in weak gravitational field, surrounded by a dense medium. The falling of the apparatus has to be governed by the equivalence principle, taking into account proper contributions to the weight of the apparatus from its material part and from distorted quantum fields. We discuss general ex pression for the corresponding force in terms of the effective action. By way of example we compute explicit expression for Archimedes force, acting on the Casimir apparatus of finite size, immersed into thermal bath of free scalar field. It is shown that besides universal term, proportional to the volume of the apparatus, there are non-universal quantum corrections, depending on the boundary conditions.

  19. It's All Connected: The Power of Proportional Reasoning to Understand Mathematics Concepts, Gr. 6-8

    ERIC Educational Resources Information Center

    Whitman, Carmen

    2011-01-01

    "It's All Connected" provides teachers of mathematics the support they need to improve their instruction. This in-demand collection of lessons for grades 6-8 explores proportionality, proportional relationships, and proportional reasoning, acknowledging that the ability to reason proportionally is crucial in the middle school mathematics…

  20. It's All Connected: The Power of Proportional Reasoning to Understand Mathematics Concepts, Gr. 6-8

    ERIC Educational Resources Information Center

    Whitman, Carmen

    2011-01-01

    "It's All Connected" provides teachers of mathematics the support they need to improve their instruction. This in-demand collection of lessons for grades 6-8 explores proportionality, proportional relationships, and proportional reasoning, acknowledging that the ability to reason proportionally is crucial in the middle school mathematics…

  1. Studies of Cosmic Rays Using Proportional Wire Chambers

    NASA Astrophysics Data System (ADS)

    Lu, Younan

    Project GRAND is an extensive air shower array using proportional wire chambers and is partially completed at the University of Notre Dame. At present, one fourth of the full array has been operating. A multi-processor controlled data acquisition system (DAS) has been designed and constructed. The DAS utilizes 68020 microprocessors designed by Advanced Computer Program group at Fermi National Laboratory, VMEbus system, 8 mm tape drive, VMEbus-SCSlbus interface and a number of custom designed electronics. The DAS can handle data acquisition at peak data rate 96 million -bit/second. The software has additional data compression and filtering capability at the system level, which makes the DAS especially efficient for the data acquisition of single tracks. The muon-electron identification experiment has been completed. The results show that the GRAND detectors can identify each recorded track as an electron or a muon. Misidentification is 3.4% and 4.4% for electrons and muons respectively. The angular correlation between single muons at sea level and their parent cosmic rays involves a number of physical processes. The first experimental investigation of this angular correlation by measuring the shadowing of primary cosmic rays by the moon, using single muons, has been performed. More than 75,000 muons per square degree in the vicinity of the moon have been accumulated during the last 12 months. The results show a deficit in a 14^circ times 14^circ aperture caused by the moon's shadow with a 3.3 sigma significance. A detailed chi-square-fitting results show the shadow of the moon matches standard two dimensional Gaussian distribution with sigma_{rm x} (east-west direction) = 5.70^circ + 1.20^circ -0.90^ circ and sigma_{ rm y} (north-south direction) = 3.00 ^circ + 0.35^ circ-0.40^circ. A smaller sigma is obtained from muons with a larger zenith angle (higher energies at birth). The added width in east-west direction is due to the deflection in the Earth's magnetic

  2. Air pollution and lymphocyte phenotype proportions in cord blood.

    PubMed

    Hertz-Picciotto, Irva; Herr, Caroline E W; Yap, Poh-Sin; Dostál, Miroslav; Shumway, Robert H; Ashwood, Paul; Lipsett, Michael; Joad, Jesse P; Pinkerton, Kent E; Srám, Radim J

    2005-10-01

    Effects of air pollution on morbidity and mortality may be mediated by alterations in immune competence. In this study we examined short-term associations of air pollution exposures with lymphocyte immunophenotypes in cord blood among 1,397 deliveries in two districts of the Czech Republic. We measured fine particulate matter < 2.5 microm in diameter (PM2.5) and 12 polycyclic aromatic hydrocarbons (PAHs) in 24-hr samples collected by versatile air pollution samplers. Cord blood samples were analyzed using a FACSort flow cytometer to determine phenotypes of CD3+ T-lymphocytes and their subsets CD4+ and CD8+, CD19+ B-lymphocytes, and natural killer cells. The mothers were interviewed regarding sociodemographic and lifestyle factors, and medical records were abstracted for obstetric, labor and delivery characteristics. During the period 1994 to 1998, the mean daily ambient concentration of PM2.5 was 24.8 microg/m3 and that of PAHs was 63.5 ng/m3. In multiple linear regression models adjusted for temperature, season, and other covariates, average PAH or PM2.5 levels during the 14 days before birth were associated with decreases in T-lymphocyte phenotype fractions (i.e., CD3+ CD4+, and CD8+), and a clear increase in the B-lymphocyte (CD19+) fraction. For a 100-ng/m3 increase in PAHs, which represented approximately two standard deviations, the percentage decrease was -3.3% [95% confidence interval (CI), -5.6 to -1.0%] for CD3+, -3.1% (95% CI, -4.9 to -1.3%) for CD4+, and -1.0% (95% CI, -1.8 to -0.2%) for CD8+ cells. The corresponding increase in the CD19+ cell proportion was 1.7% (95% CI, 0.4 to 3.0%). Associations were similar but slightly weaker for PM2.5. Ambient air pollution may influence the relative distribution of lymphocyte immunophenotypes of the fetus.

  3. The critical proportion of immune individuals needed to control hepatitis B

    NASA Astrophysics Data System (ADS)

    Ospina, Juan; Hincapié-Palacio, Doracelly

    2016-05-01

    We estimate the critical proportion of immunity (Pc) to control hepatitis B in Medellin - Colombia, based on a random population survey of 2077 individuals of 6-64 years of age. The force of infection (Fi) was estimated according to empirical data of susceptibility by age S(a), assuming a quadratic expression. Parameters were estimated by adjusting data to a nonlinear regression. Fi was defined by -(ds(a)/da)/s(a) and according to the form of the empirical curve S(a) we assume a quadratic expression given by S(a)= Ea2+Ba+C. Then we have the explicit expression for the accumulated Fi by age given by F(a) = -a(Ea+B)/c. The expression of average infection age A is obtained as A = L + EL3/(3C)+BL2/(2C) and the basic reproductive number R0 is obtained as R0 = 1 + 6C/(6C+2EL2+3BL). From the las result we obtain the Pc given by Pc= 6C/(12C+2EL2+3BL). Numerical simulations were performed with the age-susceptibility proportion and initial values (a=0.02, b=20, c=100), obtaining an adjusted coefficient of multiple determination of 64.83%. According to the best estimate, the algebraic expressions for S(a) and the Fi were derived. Using the result of Fi, we obtain A = 30, L =85; R0 CI 95%: 1.42 - 1.64 and Pc: 0-0.29. These results indicate that at the worst case, to maintain control of the disease should be immunes at least 30% of susceptible individuals. Similar results were obtained by sex and residential area.

  4. Postnatal ontogeny of limb proportions and functional indices in the subterranean rodent Ctenomys talarum (Rodentia: Ctenomyidae).

    PubMed

    Echeverría, Alejandra Isabel; Becerra, Federico; Vassallo, Aldo Iván

    2014-08-01

    Burrow construction in the subterranean Ctenomys talarum (Rodentia: Ctenomyidae) primarily occurs by scratch-digging. In this study, we compared the limbs of an ontogenetic series of C. talarum to identify variation in bony elements related to fossorial habits using a morphometrical and biomechanical approach. Diameters and functional lengths of long bones were measured and 10 functional indices were constructed. We found that limb proportions of C. talarum undergo significant changes throughout postnatal ontogeny, and no significant differences between sexes were observed. Five of six forelimb indices and two of four hindlimb indices showed differences between ages. According to discriminant analysis, the indices that contributed most to discrimination among age groups were robustness of the humerus and ulna, relative epicondylar width, crural and brachial indices, and index of fossorial ability (IFA). Particularly, pups could be differentiated from juveniles and adults by more robust humeri and ulnae, wider epicondyles, longer middle limb elements, and a proportionally shorter olecranon. Greater robustness indicated a possible compensation for lower bone stiffness while wider epicondyles may be associated to improved effective forces in those muscles that originate onto them, compensating the lower muscular development. The gradual increase in the IFA suggested a gradual enhancement in the scratch-digging performance due to an improvement in the mechanical advantage of forearm extensors. Middle limb indices were higher in pups than in juveniles-adults, reflecting relatively more gracile limbs in their middle segments, which is in accordance with their incipient fossorial ability. In sum, our results show that in C. talarum some scratch-digging adaptations are already present during early postnatal ontogeny, which suggests that they are prenatally shaped, and other traits develop progressively. The role of early digging behavior as a factor influencing on

  5. The proportionality of global warming to cumulative carbon emissions.

    PubMed

    Matthews, H Damon; Gillett, Nathan P; Stott, Peter A; Zickfeld, Kirsten

    2009-06-11

    The global temperature response to increasing atmospheric CO(2) is often quantified by metrics such as equilibrium climate sensitivity and transient climate response. These approaches, however, do not account for carbon cycle feedbacks and therefore do not fully represent the net response of the Earth system to anthropogenic CO(2) emissions. Climate-carbon modelling experiments have shown that: (1) the warming per unit CO(2) emitted does not depend on the background CO(2) concentration; (2) the total allowable emissions for climate stabilization do not depend on the timing of those emissions; and (3) the temperature response to a pulse of CO(2) is approximately constant on timescales of decades to centuries. Here we generalize these results and show that the carbon-climate response (CCR), defined as the ratio of temperature change to cumulative carbon emissions, is approximately independent of both the atmospheric CO(2) concentration and its rate of change on these timescales. From observational constraints, we estimate CCR to be in the range 1.0-2.1 degrees C per trillion tonnes of carbon (Tt C) emitted (5th to 95th percentiles), consistent with twenty-first-century CCR values simulated by climate-carbon models. Uncertainty in land-use CO(2) emissions and aerosol forcing, however, means that higher observationally constrained values cannot be excluded. The CCR, when evaluated from climate-carbon models under idealized conditions, represents a simple yet robust metric for comparing models, which aggregates both climate feedbacks and carbon cycle feedbacks. CCR is also likely to be a useful concept for climate change mitigation and policy; by combining the uncertainties associated with climate sensitivity, carbon sinks and climate-carbon feedbacks into a single quantity, the CCR allows CO(2)-induced global mean temperature change to be inferred directly from cumulative carbon emissions.

  6. Force measurements in skinned muscle fibres

    PubMed Central

    Hellam, D. C.; Podolsky, R. J.

    1969-01-01

    1. Isometric force was measured in skinned segments of frog semitendinosus muscle fibres exposed to solutions in which the calcium ion concentration was controlled with EGTA. 2. The threshold for force development, calculated from an apparent stability constant for the CaEGTA complex of 106.69 M-1 at pH 7·0, was generally close to pCa 7·5. Maximum force was reached at about pCa 6·0. 3. Maximum force is proportional to the cross-sectional area of the fibres. 4. The rate of force development was slower than that expected from simple diffusion of a substance from the bathing solution into the fibre. The delay appears to be due to slow equilibration of the EGTA buffer system during calcium uptake by the sarcoplasmic reticulum. 5. Addition of deoxycholate (DOC) to the bathing solution produced a reversible increase in the rate of force development. The steady force was also increased for values of pCa that gave less than maximum force, which shifted the force—pCa relation toward lower calcium concentrations by about 0·5 pCa unit. 6. The length—force relation in partially activated preparations is similar to that reported for electrically activated intact fibres. This result suggests that in the region of myofilament overlap the affinity of the binding sites for calcium is uniform along the length of the calciumbinding myofilament. PMID:5765859

  7. Landau-Lifshitz theory of the magnon-drag thermopower

    NASA Astrophysics Data System (ADS)

    Flebus, B.; Duine, R. A.; Tserkovnyak, Y.

    2016-09-01

    Metallic ferromagnets subjected to a temperature gradient exhibit a magnonic drag of the electric current. We address this problem by solving a stochastic Landau-Lifshitz equation to calculate the magnon-drag thermopower. The long-wavelength magnetic dynamics result in two contributions to the electromotive force acting on electrons: 1) An adiabatic Berry-phase force related to the solid angle subtended by the magnetic precession and 2) a dissipative correction thereof, which is rooted microscopically in the spin-dephasing scattering. The first contribution results in a net force pushing the electrons towards the hot side, while the second contribution drags electrons towards the cold side, i.e., in the direction of the magnonic drift. The ratio between the two forces is proportional to the ratio between the Gilbert damping coefficient α and the coefficient β parametrizing the dissipative contribution to the electromotive force.

  8. Diamagnetic force on a flux tube

    NASA Technical Reports Server (NTRS)

    Yeh, T.

    1983-01-01

    The diamagnetic force on a straight flux tube is elucidated. The case when the flux tube has a circular cross section is considered, and the result is generalized to the case of noncircular cross section. The result shows that when the external magnetic field is uniform, the diamagnetic force is simply equal to the vector multiplication of the internal conduction current and the external magnetic field. It is independent of the size and shape of the cross section of the flux tube. This is analogous to the Kutta-Joukowski theorem that the aerodynamic lift force is proportional to the vector multiplication of the unperturbed flow velocity and the circulation around the airfoil. When the external magnetic field is nonuniform, the diamagnetic force has an additional contribution which is proportional to the gradient of magnetic pressure and to the volume of the flux tube. The constant of proportionality, which is shown to be equal to two for a circular cross section, indicates the enhancement of the nonuniformity of the external magnetic field in the vicinity of the periphery by the polarization current.

  9. The swim force as a body force

    NASA Astrophysics Data System (ADS)

    Yan, Wen; Brady, John

    2015-11-01

    Net (as opposed to random) motion of active matter results from an average swim (or propulsive) force. It is shown that the average swim force acts like a body force - an internal body force [Yan and Brady, Soft Matter, DOI:10.1039/C5SM01318F]. As a result, the particle-pressure exerted on a container wall is the sum of the swim pressure [Takatori et al., Phys. Rev. Lett., 2014, 113, 028103] and the `weight' of the active particles. A continuum mechanical description is possible when variations occur on scales larger than the run length of the active particles and gives a Boltzmann-like distribution from a balance of the swim force and the swim pressure. Active particles may also display `action at a distance' and accumulate adjacent to (or be depleted from) a boundary without any external forces. In the momentum balance for the suspension - the mixture of active particles plus fluid - only external body forces appear.

  10. Avian Wing Proportions and Flight Styles: First Step towards Predicting the Flight Modes of Mesozoic Birds

    PubMed Central

    Wang, Xia; McGowan, Alistair J.; Dyke, Gareth J.

    2011-01-01

    We investigated the relationship between wing element proportions and flight mode in a dataset of living avian species to provide a framework for making basic estimates of the range of flight styles evolved by Mesozoic birds. Our results show that feather length (fprim) and total arm length (ta) (sum of the humerus, ulna and manus length) ratios differ significantly between four flight style groups defined and widely used for living birds and as a result are predictive for fossils. This was confirmed using multivariate ordination analyses, with four wing elements (humerus, ulna/radius, manus, primary feathers), that discriminate the four broad flight styles within living birds. Among the variables tested, manus length is closely correlated with wing size, yet is the poorest predictor for flight style, suggesting that the shape of the bones in the hand wing is most important in determining flight style. Wing bone thickness (shape) must vary with wing beat strength, with weaker forces requiring less bone. Finally, we show that by incorporating data from Mesozoic birds, multivariate ordination analyses can be used to predict the flight styles of fossils. PMID:22163324

  11. Energetically efficient proportional-integral-differential (PID) control of wake vortices behind a circular cylinder

    NASA Astrophysics Data System (ADS)

    Das, Pramode K.; Mathew, Sam; Shaiju, A. J.; Patnaik, B. S. V.

    2016-02-01

    The control of vortex shedding behind a circular cylinder is a precursor to a wide range of external shear flow problems in engineering, in particular the flow-induced vibrations. In the present study, numerical simulation of an energetically efficient active flow control strategy is proposed, for the control of wake vortices behind a circular cylinder at a low Reynolds number of 100. The fluid is assumed to be incompressible and Newtonian with negligible variation in properties. Reflectionally symmetric controllers are designed such that, they are located on a small sector of the cylinder over which, tangential sliding mode control is imparted. In the field of modern controls, proportional (P), integral (I) and differential (D) control strategies and their numerous combinations are extremely popular in industrial practice. To impart suitable control actuation, the vertically varying lift force on the circular cylinder, is synthesised for the construction of an error term. Four different types of controllers considered in the present study are, P, I, PI and PID. These controllers are evaluated for their energetic efficiency and performance. A linear quadratic optimal control problem is formulated, to minimise the cost functional. By performing detailed simulations, it was observed that, the system is energetically efficient, even when the twin eddies are still persisting behind the circular cylinder. To assess the adaptability of the controllers, the actuators were switched on and off to study their dynamic response.

  12. Avian wing proportions and flight styles: first step towards predicting the flight modes of mesozoic birds.

    PubMed

    Wang, Xia; McGowan, Alistair J; Dyke, Gareth J

    2011-01-01

    We investigated the relationship between wing element proportions and flight mode in a dataset of living avian species to provide a framework for making basic estimates of the range of flight styles evolved by Mesozoic birds. Our results show that feather length (f(prim)) and total arm length (ta) (sum of the humerus, ulna and manus length) ratios differ significantly between four flight style groups defined and widely used for living birds and as a result are predictive for fossils. This was confirmed using multivariate ordination analyses, with four wing elements (humerus, ulna/radius, manus, primary feathers), that discriminate the four broad flight styles within living birds. Among the variables tested, manus length is closely correlated with wing size, yet is the poorest predictor for flight style, suggesting that the shape of the bones in the hand wing is most important in determining flight style. Wing bone thickness (shape) must vary with wing beat strength, with weaker forces requiring less bone. Finally, we show that by incorporating data from Mesozoic birds, multivariate ordination analyses can be used to predict the flight styles of fossils.

  13. A new scheme of force reflecting control

    NASA Technical Reports Server (NTRS)

    Kim, Won S.

    1992-01-01

    A new scheme of force reflecting control has been developed that incorporates position-error-based force reflection and robot compliance control. The operator is provided with a kinesthetic force feedback which is proportional to the position error between the operator-commanded and the actual position of the robot arm. Robot compliance control, which increases the effective compliance of the robot, is implemented by low pass filtering the outputs of the force/torque sensor mounted on the base of robot hand and using these signals to alter the operator's position command. This position-error-based force reflection scheme combined with shared compliance control has been implemented successfully to the Advanced Teleoperation system consisting of dissimilar master-slave arms. Stability measurements have demonstrated unprecedentedly high force reflection gains of up to 2 or 3, even though the slave arm is much stiffer than operator's hand holding the force reflecting hand controller. Peg-in-hole experiments were performed with eight different operating modes to evaluate the new force-reflecting control scheme. Best task performance resulted with this new control scheme.

  14. Thermal dielectrophoretic force on a dielectric particle

    NASA Astrophysics Data System (ADS)

    Shaparenko, Barukyah; Hu, Howard; Bau, Haim

    2013-11-01

    A particle immersed in a fluid subjected simultaneously to electric and thermal fields experiences an electrostatic force given by not only classical dielectrophoresis (DEP), but also an additional force, which we term thermal DEP. Assuming the change in the background electric field across the particle and the relative change of temperature-dependent electric properties across the particle are both small, we develop a linearized model to solve the electric field analytically and integrate the Maxwell stress tensor to find an expression for the thermal DEP force for aligned electric and thermal fields. This thermal DEP force is proportional to the temperature gradient, the square of the electric field strength, and the particle's volume. We compute the fully-coupled system in COMSOL to determine a range of validity for our linearized model and show a practical way to superimpose the classical DEP and thermal DEP forces to find the total electrostatic force on the particle relative to the fluid. Additionally, we examine the thermal DEP force and torque on the particle for unaligned fields. Due to the high electrical conductivity of common biological buffers, the thermal DEP force can play an important role when an electric field is used to control and manipulate cells or bacteria.

  15. Magnus and Iordanskii Forces in Superfluids

    SciTech Connect

    Wexler, C.

    1997-08-01

    The transverse force acting on a quantized vortex in a superfluid is a problem that has eluded a complete understanding for more than three decades. In this Letter I calculate the {ital superfluid } velocity part of the transverse force in a way closely related to Laughlin{close_quote}s argument for the quantization of conductance in the quantum Hall effect. A combination of this result, the {ital vortex} velocity part of the transverse force found by Thouless, Ao, and Niu [Phys.Rev.Lett.{bold 76}, 3758 (1996)], and Galilean invariance shows that there cannot be a transverse force proportional to the normal fluid velocity. {copyright} {ital 1997} {ital The American Physical Society}

  16. Tiger beetles pursue prey using a proportional control law with a delay of one half-stride

    PubMed Central

    Haselsteiner, Andreas F.; Gilbert, Cole; Wang, Z. Jane

    2014-01-01

    Tiger beetles are fast diurnal predators capable of chasing prey under closed-loop visual guidance. We investigated this control system using statistical analyses of high-speed digital recordings of beetles chasing a moving prey dummy in a laboratory arena. Correlation analyses reveal that the beetle uses a proportional control law in which the angular position of the prey relative to the beetle's body axis drives the beetle's angular velocity with a delay of about 28 ms. The proportionality coefficient or system gain, 12 s−1, is just below critical damping. Pursuit simulations using the derived control law predict angular orientation during pursuits with a residual error of about 7°. This is of the same order of magnitude as the oscillation imposed by the beetle's alternating tripod gait, which was not factored into the control law. The system delay of 28 ms equals a half-stride period, i.e. the time between the touch down of alternating tripods. Based on these results, we propose a physical interpretation of the observed control law: to turn towards its prey, the beetle on average exerts a sideways force proportional to the angular position of the prey measured a half-stride earlier. PMID:24718454

  17. Measuring the Drag Force on a Falling Ball

    NASA Astrophysics Data System (ADS)

    Cross, Rod; Lindsey, Crawford

    2014-03-01

    The effect of the aerodynamic drag force on an object in flight is well known and has been described in this and other journals many times. At speeds less than about 1 m/s, the drag force on a sphere is proportional to the speed and is given by Stokes' law. At higher speeds, the drag force is proportional to the velocity squared and is usually small compared with the gravitational force if the object mass is large and its speed is low. In order to observe a significant effect, or to measure the terminal velocity, experiments are often conducted with very light objects such as a balloon or coffee filter3 or muffin cup,4 or are conducted in a liquid rather than in air. The effect of the drag force can also be increased by increasing the surface area of the object.

  18. The Development of Proportional Reasoning: Effect of Continuous versus Discrete Quantities

    ERIC Educational Resources Information Center

    Jeong, Yoonkyung; Levine, Susan C.; Huttenlocher, Janellen

    2007-01-01

    This study examines the development of children's ability to reason about proportions that involve either discrete entities or continuous amounts. Six-, 8- and 10-year olds were presented with a proportional reasoning task in the context of a game involving probability. Although all age groups failed when proportions involved discrete quantities,…

  19. Proportions of Women Faculty and Students in the Mathematical Sciences: A Trend Analysis by Institutional Group.

    ERIC Educational Resources Information Center

    Sharpe, Norean Radke; Sonnert, Gerhard

    1999-01-01

    Examines how gender proportions of faculty and undergraduate majors in the mathematical sciences vary across institutional groups and how these proportions have changed over time. Explores the relationship between the proportion of women faculty and women majors across institutional types as a test of the role-model hypothesis. Contains 36…

  20. Proportional Reasoning: How Do the 4th Graders Use Their Intuitive Understanding?

    ERIC Educational Resources Information Center

    Sumarto, Sylvana Novilia; van Galen, Frans; Zulkardi, H.; Darmawijoyo, D.

    2014-01-01

    In Indonesia, proportion is being taught formally in Grade 5 (10-11 years old). However, the existing learning approach does not support the development of the students' proportional reasoning. The way to teach proportion by giving cross multiplication is not meaningful for the students. They just memorize the procedure without understanding how…

  1. Icelandic 5th-Grade Girls' Developmental Trajectories in Proportional Reasoning

    ERIC Educational Resources Information Center

    Steinthorsdottir, Olof B.; Sriraman, Bharath

    2009-01-01

    Understanding of ratio and proportion is critical to the development of higher level mathematical skills. Following Carpenter, Gomez, et al.'s (1999) proposal of a four-level trajectory in the development of proportional reasoning, a 12-week investigation was undertaken of the developmental trajectory of proportional reasoning of girls in two…

  2. The Contribution of Domain-Specific Knowledge in Predicting Students' Proportional Word Problem-Solving Performance

    ERIC Educational Resources Information Center

    Jitendra, Asha K.; Lein, Amy E.; Star, Jon R.; Dupuis, Danielle N.

    2013-01-01

    This study explored the extent to which domain-specific knowledge predicted proportional word problem-solving performance. We tested 411 seventh-grade students on conceptual and procedural fraction knowledge, conceptual and procedural proportion knowledge, and proportional word problem solving. Multiple regression analyses indicated that all four…

  3. Lag-stabilized force feedback damping

    SciTech Connect

    Petterson, B.J.; Robinett, R.D.; Werner, J.C.

    1991-05-01

    A lag-stabilized, force feedback controller for damping initial and residual oscillations of a planar, cantilevered flexible arm has been analytically developed and experimentally implemented on a commercial robot. The controller feeds back force sensor measurements that are delayed in time and proportional to the displacement (angular orientation) of the arm in order to damp the oscillation. As a result of the lag (contrary to popular belief), the controlled robot system is stable and provides tunable performance on a Cincinnati Milacron T3-786 robot. 3 refs., 9 figs., 2 tabs.

  4. Observations on the ponderomotive force

    NASA Astrophysics Data System (ADS)

    Burton, D. A.; Cairns, R. A.; Ersfeld, B.; Noble, A.; Yoffe, S.; Jaroszynski, D. A.

    2017-05-01

    The ponderomotive force is an important concept in plasma physics and, in particular, plays an important role in many aspects of the theory of laser plasma interactions including current concerns like wakefield acceleration and Raman amplification. The most familiar form of this gives a force on a charged particle that is proportional to the slowly varying gradient of the intensity of a high frequency electromagnetic field and directed down the intensity gradiant. For a field amplitude simply oscillating in time there is a simple derivation of this formula, but in the more general case of a travelling wave the problem is more difficult. Over the years there has been much work on this using Hamiltonian or Lagrangian averaging techniques, but little or no investigation of how well these theories work. Here we look at the very basic problem of a particle entering a region with a monotonically increasing electrostatic field amplitude and being reflected. We show that the equation of motion derived from a widely quoted ponderomotive potential only agrees with the numerically computed orbit within a restricted parameter range and that outside this range it shows features which are inconsistent with any ponderomotive potential quadratic in the field amplitude. Since the ponderomotive force plays a fundamental role in a variety of problems in plasma physics we think that it is important to point out that even in the simplest of configurations standard theories may not be accurate.

  5. Ground reaction force comparison of controlled resistance methods to isoinertial loading of the squat exercise - biomed 2010.

    PubMed

    Paulus, David C; Reynolds, Michael C; Schilling, Brian K

    2010-01-01

    The ground reaction force during the concentric (raising) portion of the squat exercise was compared to that of isoinertial loading (free weights) for three pneumatically controlled resistance methods: constant resistance, cam force profile, and proportional force control based on velocity. Constant force control showed lower ground reaction forces than isoinertial loading throughout the range of motion (ROM). The cam force profile exhibited slightly greater ground reaction forces than isoinertial loading at 10 and 40% ROM with fifty-percent greater loading at 70% ROM. The proportional force control consistently elicited greater ground reaction force than isoinertial loading, which progressively ranged from twenty to forty percent increase over isoinertial loading except for being approximately equal at 85% ROM. Based on these preliminary results, the proportional control shows the most promise for providing loading that is comparable in magnitude to isoinertial loading. This technology could optimize resistance exercise for sport-specific training or as a countermeasure to atrophy during spaceflight.

  6. The proportions of muscle, bone and fat in two different types of dog.

    PubMed

    Gunn, H M

    1978-05-01

    This study compares the proportions of muscle, bone and fat (obtained by gross dissection) in greyhounds--a breed selected for high speed running--and other dogs, both at maturity and during growth. In adults the proportion of muscle is significantly greater in the 'athletic' greyhound. The proportion of muscle decreases but not significantly with detraining. Adult greyhounds have less fat (even when detrained) than other dogs, but the skeleton provides a similar proportion of liveweight in both types of dog when adult. The greater growth rate of muscle in athletes explains the difference in adult proportions.

  7. A Biomechanical Comparison of Proportional Electromyography Control to Biological Torque Control Using a Powered Hip Exoskeleton.

    PubMed

    Young, Aaron J; Gannon, Hannah; Ferris, Daniel P

    2017-01-01

    Despite a large increase in robotic exoskeleton research, there are few studies that have examined human performance with different control strategies on the same exoskeleton device. Direct comparison studies are needed to determine how users respond to different types of control. The purpose of this study was to compare user performance using a robotic hip exoskeleton with two different controllers: a controller that targeted a biological hip torque profile and a proportional myoelectric controller. We tested both control approaches on 10 able-bodied subjects using a pneumatically powered hip exoskeleton. The state machine controller targeted a biological hip torque profile. The myoelectric controller used electromyography (EMG) of lower limb muscles to produce a proportional control signal for the hip exoskeleton. Each subject performed two 30-min exoskeleton walking trials (1.0 m/s) using each controller and a 10-min trial with the exoskeleton unpowered. During each trial, we measured subjects' metabolic cost of walking, lower limb EMG profiles, and joint kinematics and kinetics (torques and powers) using a force treadmill and motion capture. Compared to unassisted walking in the exoskeleton, myoelectric control significantly reduced metabolic cost by 13% (p = 0.005) and biological hip torque control reduced metabolic cost by 7% (p = 0.261). Subjects reduced muscle activity relative to the unpowered condition for a greater number of lower limb muscles using myoelectric control compared to the biological hip torque control. More subjects subjectively preferred the myoelectric controller to the biological hip torque control. Myoelectric control had more advantages (metabolic cost and muscle activity reduction) compared to a controller that targeted a biological torque profile for walking with a robotic hip exoskeleton. However, these results were obtained with a single exoskeleton device with specific control configurations while level walking at a

  8. Problem based learning to improve proportional reasoning of students in mathematics learning

    NASA Astrophysics Data System (ADS)

    Misnasanti, Utami, Ratna Widianti; Suwanto, Fevi Rahmawati

    2017-08-01

    This paper reviews about the using of Problem Based Learning (PBL) to improve proportional reasoning of students in mathematics learning. Mathematics is one of the subjects at school which generally has a goal to help students preparing themselves in this growth century. To achieve the goal of mathematics learning, student's good reasoning is needed as the base of mathematics itself. This reasoning is an ability to think through logic ideas about mathematics concept. One of reasoning mathematics ability is the proportional reasoning. Proportional reasoning is knowing the multiplicative relationship between the base ratio and the proportional situation to which it's applied. Proportional reasoning is important to have by students in learning mathematics. Many topics within the school mathematics require knowledge and understanding of ratio and proportion, for examples problem solving and calculation activities in domains involving scale, probability, percent, rate, trigonometry, equivalence, measurement, the geometry of plane shapes, algebra are assisted through ratio and proportion knowledge. But, the mastership of proportional reasoning ability, of course, can't be apart from teacher's role. In learning, a teacher has to choose and apply the right model so that it can improve the proportional reasoning ability of students. One of the alternative ways which could be applied to improve proportional reasoning ability of students is by applying PBL Model. Applying PBL which based on problem indirectly has trained students to solve every problem in front of them. Thus, applying PBL can improve mathematics proportional reasoning of students in mathematics learning.

  9. Proportional reasoning as a heuristic-based process: time constraint and dual task considerations.

    PubMed

    Gillard, Ellen; Van Dooren, Wim; Schaeken, Walter; Verschaffel, Lieven

    2009-01-01

    The present study interprets the overuse of proportional solution methods from a dual process framework. Dual process theories claim that analytic operations involve time-consuming executive processing, whereas heuristic operations are fast and automatic. In two experiments to test whether proportional reasoning is heuristic-based, the participants solved "proportional" problems, for which proportional solution methods provide correct answers, and "nonproportional" problems known to elicit incorrect answers based on the assumption of proportionality. In Experiment 1, the available solution time was restricted. In Experiment 2, the executive resources were burdened with a secondary task. Both manipulations induced an increase in proportional answers and a decrease in correct answers to nonproportional problems. These results support the hypothesis that the choice for proportional methods is heuristic-based.

  10. Analyzing Proportion Scores as Outcomes for Prevention Trials: a Statistical Primer.

    PubMed

    Chen, Kehui; Cheng, Yu; Berkout, Olga; Lindhiem, Oliver

    2016-03-10

    In prevention trials, outcomes of interest frequently include data that are best quantified as proportion scores. In some cases, however, proportion scores may violate the statistical assumptions underlying common analytic methods. In this paper, we provide guidelines for analyzing frequency and proportion data as primary outcomes. We describe standard methods including generalized linear regression models to compare mean proportion scores and examine tools for testing normality and other assumptions for each model. Recommendations are made for instances when the assumptions are not met, including transformations for proportion scores that are non-normal. We also discuss more sophisticated analytical tools to model change in proportion scores over time. The guidelines provide ready-to-use analytical strategies for frequency and proportion data that are commonly encountered in prevention science.

  11. Effects of grasping force magnitude on the coordination of digit forces in multi-finger prehension.

    PubMed

    Niu, Xun; Latash, Mark L; Zatsiorsky, Vladimir M

    2009-03-01

    The study addresses three main questions: (1) Does the magnitude of the grasping force affect the prehension synergies, i.e., conjoint changes of finger forces and moments? (2) Do individual finger forces scale with the total grasping forces ('scale-invariance hypothesis')? (3) How specification of the grasping force magnitude affects the inverse optimization of digit forces. Subjects (n = 7) grasped with minimal force an instrumented handle and maintained it at rest in the air. Then, the subjects doubled the initial grasping force. The forces and moments exerted by individual digits were recorded with six-component sensors. External torques that the subjects should resist (9 in total) varied among the trials from 0 to 0.46 Nm both in clockwise and counterclockwise directions. After the force doubling, the moments of the normal forces (M (n)) increased in the pronation effort tasks (PR-tasks) and decreased in the supination effort tasks (SU-tasks). The changes in the moments of the tangential forces (M (t)) were opposite to the M (n) changes; the moments increased in the SU-tasks and decreased in the PR-tasks. The opposite effects of force doubling on the M (t)s in the SU-tasks and PR-tasks were a consequence of the unidirectional changes of the thumb tangential forces: in all the tasks the contribution of the thumb tangential force to the total tangential force increased after the grasping force doubling (and the total contribution of the four fingers decreased). The decrease of the virtual finger (VF) tangential force was mainly due to the decrease of the index finger force (VF is an imagined finger that exerts the same force and moment as all the fingers together). In the non-zero torque tasks the individual finger forces did not scale proportionally with the grasping force, the sharing percentage of the individual finger forces in the VF normal force changed with the grasping force increase. The root mean square differences between the actual finger sharing

  12. Transverse force on a quantized vortex in a superfluid

    SciTech Connect

    Thouless, D.J.; Ao, P.; Niu, Q. ||

    1996-05-01

    We have derived an exact expression for the total nondissipative transverse force acting on a quantized vortex moving in a uniform background. The derivation is valid for neutral boson or fermion superfluids, provided the order parameter is a complex scalar quantity. This force is determined by the one-particle density matrix far away from the vortex core, and is found to be the Magnus force proportional to the superfluid density. We conclude that contributions of the localized core states do not change this force. {copyright} {ital 1996 The American Physical Society.}

  13. Direct measurement of Vorticella contraction force by micropipette deflection.

    PubMed

    France, Danielle; Tejada, Jonathan; Matsudaira, Paul

    2017-02-01

    The ciliated protozoan Vorticella convallaria is noted for its exceptionally fast adenosine triphosphate-independent cellular contraction, but direct measurements of contractile force have proven difficult given the length scale, speed, and forces involved. We used high-speed video microscopy to image live Vorticella stalled in midcontraction by deflection of an attached micropipette. Stall forces correlate with both distance contracted and the resting stalk length. Estimated isometric forces range from 95 to 177 nanonewtons (nN), or 1.12 nN·μm(-1) of the stalk. Maximum velocity and work are also proportional to distance contracted. These parameters constrain proposed biochemical/physical models of the contractile mechanism.

  14. Proportional Smile Design: Using the Recurring Esthetic Dental Proportion to Correlate the Widths and Lengths of the Maxillary Anterior Teeth with the Size of the Face.

    PubMed

    Ward, Daniel H

    2015-07-01

    Proportional smile design is a useful tool for evaluating and designing smiles that are in harmony with the face. Although not always observed in nature, the recurring esthetic dental proportion is preferred by dentists surveyed to the width proportions observed in nature with normal-length teeth. The width/length ratio of the central incisor is a key determinant in providing a smile that is pleasing to dentists. Using the desired tooth length while maintaining the preferred 78% width/length ratio of the central incisor in conjunction with the recommended recurring esthetic dental proportion is a good method for designing a smile balanced with the face. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Theoretical Model and Experimental Validation of the estimated proportions of common and independent input to motor neurons.

    PubMed

    Castronovo, A Margherita; Negro, Francesco; Farina, Dario

    2015-01-01

    Motor neurons in the spinal cord receive synaptic input that comprises common and independent components. The part of synaptic input that is common to all motor neurons is the one regulating the production of force. Therefore, its quantification is important to assess the strategy used by Central Nervous System (CNS) to control and regulate movements, especially in physiological conditions such as fatigue. In this study we present and validate a method to estimate the ratio between strengths of common and independent inputs to motor neurons and we apply this method to investigate its changes during fatigue. By means of coherence analysis we estimated the level of correlation between motor unit spike trains at the beginning and at the end of fatiguing contractions of the Tibialis Anterior muscle at three different force targets. Combining theoretical modeling and experimental data we estimated the strength of the common synaptic input with respect to the independent one. We observed a consistent increase in the proportion of the shared input to motor neurons during fatigue. This may be interpreted as a strategy used by the CNS to counteract the occurrence of fatigue and the concurrent decrease of generated force.

  16. Screened Casimir forces

    NASA Astrophysics Data System (ADS)

    Tomaš, M. S.

    2005-06-01

    We demonstrate that a very recently obtained formula for the force on a slab in a material planar cavity based on the calculation of the vacuum Lorentz force [C. Raabe and D.-G. Welsch, Phys. Rev. A 71, 013814 (2005)] describes a (medium) modified Casimir force and, in addition to it, a medium-assisted force. The latter force also describes the force on the cavity medium. For dilute media, it implies the atom-mirror interaction of the Casimir-Polder type at large and of the Coulomb type at small atom-mirror distances of which the sign is insensitive to the polarizability type (electric or magnetic) of the atom.

  17. Nanonet Force Microscopy for Measuring Cell Forces.

    PubMed

    Sheets, Kevin; Wang, Ji; Zhao, Wei; Kapania, Rakesh; Nain, Amrinder S

    2016-07-12

    The influence of physical forces exerted by or felt by cells on cell shape, migration, and cytoskeleton arrangement is now widely acknowledged and hypothesized to occur due to modulation of cellular inside-out forces in response to changes in the external fibrous environment (outside-in). Our previous work using the non-electrospinning Spinneret-based Tunable Engineered Parameters' suspended fibers has revealed that cells are able to sense and respond to changes in fiber curvature and structural stiffness as evidenced by alterations to focal adhesion cluster lengths. Here, we present the development and application of a suspended nanonet platform for measuring C2C12 mouse myoblast forces attached to fibers of three diameters (250, 400, and 800 nm) representing a wide range of structural stiffness (3-50 nN/μm). The nanonet force microscopy platform measures cell adhesion forces in response to symmetric and asymmetric external perturbation in single and cyclic modes. We find that contractility-based, inside-out forces are evenly distributed at the edges of the cell, and that forces are dependent on fiber structural stiffness. Additionally, external perturbation in symmetric and asymmetric modes biases cell-fiber failure location without affecting the outside-in forces of cell-fiber adhesion. We then extend the platform to measure forces of (1) cell-cell junctions, (2) single cells undergoing cyclic perturbation in the presence of drugs, and (3) cancerous single-cells transitioning from a blebbing to a pseudopodial morphology. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  18. Aerodynamic Lifting Force.

    ERIC Educational Resources Information Center

    Weltner, Klaus

    1990-01-01

    Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)

  19. Aerodynamic Lifting Force.

    ERIC Educational Resources Information Center

    Weltner, Klaus

    1990-01-01

    Describes some experiments showing both qualitatively and quantitatively that aerodynamic lift is a reaction force. Demonstrates reaction forces caused by the acceleration of an airstream and the deflection of an airstream. Provides pictures of demonstration apparatus and mathematical expressions. (YP)

  20. The Strong Nuclear Force

    SciTech Connect

    Lincoln, Don

    2016-05-24

    Scientists are aware of four fundamental forces- gravity, electromagnetism, and the strong and weak nuclear forces. Most people have at least some familiarity with gravity and electromagnetism, but not the other two. How is it that scientists are so certain that two additional forces exist? In this video, Fermilab’s Dr. Don Lincoln explains why scientists are so certain that the strong force exists.

  1. Fluid force transducer

    DOEpatents

    Jendrzejczyk, Joseph A.

    1982-01-01

    An electrical fluid force transducer for measuring the magnitude and direction of fluid forces caused by lateral fluid flow, includes a movable sleeve which is deflectable in response to the movement of fluid, and a rod fixed to the sleeve to translate forces applied to the sleeve to strain gauges attached to the rod, the strain gauges being connected in a bridge circuit arrangement enabling generation of a signal output indicative of the magnitude and direction of the force applied to the sleeve.

  2. The Strong Nuclear Force

    ScienceCinema

    Lincoln, Don

    2016-07-12

    Scientists are aware of four fundamental forces- gravity, electromagnetism, and the strong and weak nuclear forces. Most people have at least some familiarity with gravity and electromagnetism, but not the other two. How is it that scientists are so certain that two additional forces exist? In this video, Fermilab’s Dr. Don Lincoln explains why scientists are so certain that the strong force exists.

  3. Forces in General Relativity

    ERIC Educational Resources Information Center

    Ridgely, Charles T.

    2010-01-01

    Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…

  4. Crossflow force transducer. [LMFBR

    SciTech Connect

    Mulcahy, T M

    1982-05-01

    A force transducer for measuring lift and drag coefficients for a circular cylinder in turbulent water flow is presented. In addition to describing the actual design and construction of the strain-gauged force- ring based transducer, requirements for obtained valid fluid force test data are discussed, and pertinent flow test experience is related.

  5. Debunking Coriolis Force Myths

    ERIC Educational Resources Information Center

    Shakur, Asif

    2014-01-01

    Much has been written and debated about the Coriolis force. Unfortunately, this has done little to demystify the paradoxes surrounding this fictitious force invoked by an observer in a rotating frame of reference. It is the purpose of this article to make another valiant attempt to slay the dragon of the Coriolis force! This will be done without…

  6. Debunking Coriolis Force Myths

    ERIC Educational Resources Information Center

    Shakur, Asif

    2014-01-01

    Much has been written and debated about the Coriolis force. Unfortunately, this has done little to demystify the paradoxes surrounding this fictitious force invoked by an observer in a rotating frame of reference. It is the purpose of this article to make another valiant attempt to slay the dragon of the Coriolis force! This will be done without…

  7. Forces in General Relativity

    ERIC Educational Resources Information Center

    Ridgely, Charles T.

    2010-01-01

    Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…

  8. Chemical Principles Revisited: Artifacts and the Electromotive Series.

    ERIC Educational Resources Information Center

    Mickey, Charles D.

    1980-01-01

    Reviews chemical information relevant to the study of archeology and specifically to the history of man's use of metals. Gives reasons why most significant artifacts found by archeologists are made of gold instead of iron. (CS)

  9. Neural control of muscle force: indications from a simulation model

    PubMed Central

    Luca, Carlo J. De

    2013-01-01

    We developed a model to investigate the influence of the muscle force twitch on the simulated firing behavior of motoneurons and muscle force production during voluntary isometric contractions. The input consists of an excitatory signal common to all the motor units in the pool of a muscle, consistent with the “common drive” property. Motor units respond with a hierarchically structured firing behavior wherein at any time and force, firing rates are inversely proportional to recruitment threshold, as described by the “onion skin” property. Time- and force-dependent changes in muscle force production are introduced by varying the motor unit force twitches as a function of time or by varying the number of active motor units. A force feedback adjusts the input excitation, maintaining the simulated force at a target level. The simulations replicate motor unit behavior characteristics similar to those reported in previous empirical studies of sustained contractions: 1) the initial decrease and subsequent increase of firing rates, 2) the derecruitment and recruitment of motor units throughout sustained contractions, and 3) the continual increase in the force fluctuation caused by the progressive recruitment of larger motor units. The model cautions the use of motor unit behavior at recruitment and derecruitment without consideration of changes in the muscle force generation capacity. It describes an alternative mechanism for the reserve capacity of motor units to generate extraordinary force. It supports the hypothesis that the control of motoneurons remains invariant during force-varying and sustained isometric contractions. PMID:23236008

  10. Equilibrium capillary forces with atomic force microscopy.

    PubMed

    Sprakel, J; Besseling, N A M; Leermakers, F A M; Cohen Stuart, M A

    2007-09-07

    We present measurements of equilibrium forces resulting from capillary condensation. The results give access to the ultralow interfacial tensions between the capillary bridge and the coexisting bulk phase. We demonstrate this with solutions of associative polymers and an aqueous mixture of gelatin and dextran, with interfacial tensions around 10 microN/m. The equilibrium nature of the capillary forces is attributed to the combination of a low interfacial tension and a microscopic confinement geometry, based on nucleation and growth arguments.

  11. An imaging gas scintillation proportional counter for the detection of subkiloelectron-volt X-rays

    NASA Technical Reports Server (NTRS)

    Hailey, C. J.; Ku, W. H. M.; Vartanian, M. H.

    1981-01-01

    A large area imaging gas scintillation proportional counter (IGSPC) was constructed for use in X-ray astronomy. The IGSPC consists of a gas scintillation proportional counted (GSPC) with a micron polyprotylene window coupled to a multiwire proportional counter (MWPC) via a calcium fluoride window. Over a sensitive area of 21 cu cm the instrument has a measured energy resolution of 17.5% (FWHM) and 1.9 mm (FWHM) spatial resolution at 1.5 keV.

  12. Growth Optimal Portfolio Selection Under Proportional Transaction Costs with Obligatory Diversification

    SciTech Connect

    Duncan, T. Pasik Duncan, B.; Stettner, L.

    2011-02-15

    A continuous time long run growth optimal or optimal logarithmic utility portfolio with proportional transaction costs consisting of a fixed proportional cost and a cost proportional to the volume of transaction is considered. The asset prices are modeled as exponent of diffusion with jumps whose parameters depend on a finite state Markov process of economic factors. An obligatory portfolio diversification is introduced, accordingly to which it is required to invest at least a fixed small portion of our wealth in each asset.

  13. Motor force homeostasis in skeletal muscle contraction.

    PubMed

    Chen, Bin; Gao, Huajian

    2011-07-20

    In active biological contractile processes such as skeletal muscle contraction, cellular mitosis, and neuronal growth, an interesting common observation is that multiple motors can perform coordinated and synchronous actions, whereas individual myosin motors appear to randomly attach to and detach from actin filaments. Recent experiment has demonstrated that, during skeletal muscle shortening at a wide range of velocities, individual myosin motors maintain a force of ~6 pN during a working stroke. To understand how such force-homeostasis can be so precisely regulated in an apparently chaotic system, here we develop a molecular model within a coupled stochastic-elastic theoretical framework. The model reveals that the unique force-stretch relation of myosin motor and the stochastic behavior of actin-myosin binding cause the average number of working motors to increase in linear proportion to the filament load, so that the force on each working motor is regulated at ~6 pN, in excellent agreement with experiment. This study suggests that it might be a general principle to use catch bonds together with a force-stretch relation similar to that of myosin motors to regulate force homeostasis in many biological processes. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  14. Effect of arrangement of stick figures on estimates of proportion in risk graphics.

    PubMed

    Ancker, Jessica S; Weber, Elke U; Kukafka, Rita

    2011-01-01

    Health risks are sometimes illustrated with stick figures, with a certain proportion colored to indicate they are affected by the disease. Perception of these graphics may be affected by whether the affected stick figures are scattered randomly throughout the group or arranged in a block. . To assess the effects of stick-figure arrangement on first impressions of estimates of proportion, under a 10-s deadline. . Questionnaire. Participants and Setting. Respondents recruited online (n = 100) or in waiting rooms at an urban hospital (n = 65). Intervention. Participants were asked to estimate the proportion represented in 6 unlabeled graphics, half randomly arranged and half sequentially arranged. Measurements. Estimated proportions. . Although average estimates were fairly good, the variability of estimates was high. Overestimates of random graphics were larger than overestimates of sequential ones, except when the proportion was near 50%; variability was also higher with random graphics. Although the average inaccuracy was modest, it was large enough that more than one quarter of respondents confused 2 graphics depicting proportions that differed by 11 percentage points. Low numeracy and educational level were associated with inaccuracy. Limitations. Participants estimated proportions but did not report perceived risk. . Randomly arranged arrays of stick figures should be used with care because viewers' ability to estimate the proportion in these graphics is so poor that moderate differences between risks may not be visible. In addition, random arrangements may create an initial impression that proportions, especially large ones, are larger than they are.

  15. Effect of Arrangement of Stick Figures on Estimates of Proportion in Risk Graphics

    PubMed Central

    Ancker, Jessica S.; Weber, Elke U.; Kukafka, Rita

    2017-01-01

    Background Health risks are sometimes illustrated with stick figures, with a certain proportion colored to indicate they are affected by the disease. Perception of these graphics may be affected by whether the affected stick figures are scattered randomly throughout the group or arranged in a block. Objective To assess the effects of stick-figure arrangement on first impressions of estimates of proportion, under a 10-s deadline. Design Questionnaire. Participants and Setting Respondents recruited online (n = 100) or in waiting rooms at an urban hospital (n = 65). Intervention Participants were asked to estimate the proportion represented in 6 unlabeled graphics, half randomly arranged and half sequentially arranged. Measurements Estimated proportions. Results Although average estimates were fairly good, the variability of estimates was high. Overestimates of random graphics were larger than overestimates of sequential ones, except when the proportion was near 50%; variability was also higher with random graphics. Although the average inaccuracy was modest, it was large enough that more than one quarter of respondents confused 2 graphics depicting proportions that differed by 11 percentage points. Low numeracy and educational level were associated with inaccuracy. Limitations Participants estimated proportions but did not report perceived risk. Conclusions Randomly arranged arrays of stick figures should be used with care because viewers’ ability to estimate the proportion in these graphics is so poor that moderate differences between risks may not be visible. In addition, random arrangements may create an initial impression that proportions, especially large ones, are larger than they are. PMID:20671209

  16. Variation in limb proportions between Jomon foragers and Yayoi agriculturalists from prehistoric Japan.

    PubMed

    Temple, Daniel H; Auerbach, Benjamin M; Nakatsukasa, Masato; Sciulli, Paul W; Larsen, Clark Spencer

    2008-10-01

    Variation in limb proportions between prehistoric Jomon and Yayoi people of Japan are explored by this study. Jomon people were the descendents of Pleistocene nomads who migrated to the Japanese Islands around 30,000 yBP. Phenotypic and genotypic evidence indicates that Yayoi people were recent migrants to Japan from continental Northeast Asia who likely interbred with Jomon foragers. Limb proportions of Jomon and Yayoi people were compared using RMA regression and "Quick-Test" calculations to investigate relative variability between these two groups. Cluster and principal components analyses were performed on size-standardized limb lengths and used to compare Jomon and Yayoi people with other groups from various climatic zones. Elongated distal relative to proximal limb lengths were observed among Jomon compared to Yayoi people. Jomon limb proportions were similar to human groups from temperate/tropical climates at lower latitudes, while Yayoi limb proportions more closely resemble groups from colder climates at higher latitudes. Limb proportional similarities with groups from warmer environments among Jomon foragers likely reflect morphological changes following Pleistocene colonization of the Japanese Islands. Cold-derived limb proportions among the Yayoi people likely indicate retention of these traits following comparatively recent migrations to the Japanese Islands. Changes in limb proportions experienced by Jomon foragers and retention of cold-derived limb proportions among Yayoi people conform to previous findings that report changes in these proportions following long-standing evolution in a specific environment.

  17. Clinging to the Past: The Air Force’s War on Dual-Career Families

    DTIC Science & Technology

    2014-06-01

    bias that negatively affects Air Force spouses, families, Airmen, and the Air Force workforce. When one combines these negative effects with the growing...Force spouses, families, Airmen, and the Air Force workforce. When one combines these negative effects with the growing proportion of dual-career...family conflict can have a negative impact on the workforce. Bellavia and Frone list “job satisfaction, effectiveness , turnover,” and increased family

  18. Efficacy of climate forcings

    NASA Astrophysics Data System (ADS)

    Hansen, J.; Sato, M.; Ruedy, R.; Nazarenko, L.; Lacis, A.; Schmidt, G. A.; Russell, G.; Aleinov, I.; Bauer, M.; Bauer, S.; Bell, N.; Cairns, B.; Canuto, V.; Chandler, M.; Cheng, Y.; Del Genio, A.; Faluvegi, G.; Fleming, E.; Friend, A.; Hall, T.; Jackman, C.; Kelley, M.; Kiang, N.; Koch, D.; Lean, J.; Lerner, J.; Lo, K.; Menon, S.; Miller, R.; Minnis, P.; Novakov, T.; Oinas, V.; Perlwitz, Ja.; Perlwitz, Ju.; Rind, D.; Romanou, A.; Shindell, D.; Stone, P.; Sun, S.; Tausnev, N.; Thresher, D.; Wielicki, B.; Wong, T.; Yao, M.; Zhang, S.

    2005-09-01

    We use a global climate model to compare the effectiveness of many climate forcing agents for producing climate change. We find a substantial range in the "efficacy" of different forcings, where the efficacy is the global temperature response per unit forcing relative to the response to CO2 forcing. Anthropogenic CH4 has efficacy ˜110%, which increases to ˜145% when its indirect effects on stratospheric H2O and tropospheric O3 are included, yielding an effective climate forcing of ˜0.8 W/m2 for the period 1750-2000 and making CH4 the largest anthropogenic climate forcing other than CO2. Black carbon (BC) aerosols from biomass burning have a calculated efficacy ˜58%, while fossil fuel BC has an efficacy ˜78%. Accounting for forcing efficacies and for indirect effects via snow albedo and cloud changes, we find that fossil fuel soot, defined as BC + OC (organic carbon), has a net positive forcing while biomass burning BC + OC has a negative forcing. We show that replacement of the traditional instantaneous and adjusted forcings, Fi and Fa, with an easily computed alternative, Fs, yields a better predictor of climate change, i.e., its efficacies are closer to unity. Fs is inferred from flux and temperature changes in a fixed-ocean model run. There is remarkable congruence in the spatial distribution of climate change, normalized to the same forcing Fs, for most climate forcing agents, suggesting that the global forcing has more relevance to regional climate change than may have been anticipated. Increasing greenhouse gases intensify the Hadley circulation in our model, increasing rainfall in the Intertropical Convergence Zone (ITCZ), Eastern United States, and East Asia, while intensifying dry conditions in the subtropics including the Southwest United States, the Mediterranean region, the Middle East, and an expanding Sahel. These features survive in model simulations that use all estimated forcings for the period 1880-2000. Responses to localized forcings, such

  19. Combustion and Magnetohydrodynamic Processes in Advanced Pulse Detonation Rocket Engines

    DTIC Science & Technology

    2012-10-01

    itself is a conductor of electricity, the motion of this fluid through a magnetic field gives rise to electromotive force (drag) and flow current in...the system resulting in an electromotive force (thrust). In the AJAX system, energy is diverted from the inlet flow via MHD generation, it is then re...engine configurations explored and reviewed in this dis- sertation utilize electromotive forces (Lorentz forces) generated by a moving charge to augment

  20. Entropic force between biomembranes

    NASA Astrophysics Data System (ADS)

    Li, Long; Song, Fan

    2016-10-01

    Undulation force, an entropic force, stems from thermally excited fluctuations, and plays a key role in the essential interactions between neighboring surfaces of objects. Although the characteristics of the undulation force have been widely studied theoretically and experimentally, the distance dependence of the force, which constitutes its most fundamental characteristic, remains poorly understood. In this paper, first, we obtain a novel expression for the undulation force by employing elasticity and statistical mechanics and prove it to be in good agreement with existing experimental results. Second, we clearly demonstrate that the two representative forms of the undulation force proposed by Helfrich and Freund were respectively the upper and lower bounds of the present expression when the separation between membranes is sufficiently small, which was intrinsically different from the existing results where Helfrich's and Freund's forms of the undulation force were only suitable for the intermediate and small separations. The investigations show that only in a sufficiently small separation does Helfrich's result stand for the undulation force with a large wave number and Freund's result express the force with a small wave number. Finally, a critical acting distance of the undulation force, beyond which the entropic force will rapidly decay approaching zero, is presented.