Full Revolution Research Articles

Relationship between the increase of effectiveness indexes and the increase of muscular efficiency with cycling power

We determined the index of effectiveness (IE), as defined by the ratio of the tangential (effective force) to the total force applied on the pedals, using a new method proposed by Mornieux et al. (J Biomech, 2005), while simultaneously measuring the muscular efficiency during sub-maximal cycling tests of different intensities. This allowed us to verify whether part of the changes in muscular efficiency could be explained by a better orientation of the force applied on the pedals. Ten subjects were asked to perform an incremental test to exhaustion, starting at 100 W and with 30 W increments every 5 min, at 80 rpm. Gross (GE) and net (NE) efficiencies were calculated from the oxygen uptake and W(Ext) measurements. From the three-dimensional force's measurements, it was possible to measure the total force (F(Tot)), including the effective (F(Tang)) and ineffective force (F (Rad + Lat)). IE has been determined as the ratio between F(Tang) and F(Tot), applied on the pedals for three different time intervals, i.e., during the full revolution (IE(360 degrees)), the downstroke phase (IE(180 degrees Desc)) and the upstroke phase (IE(180 degrees Asc)). IE(360 degrees) and IE(180 degrees Asc) were significantly correlated with GE (r = 0.79 and 0.66, respectively) and NE (r = 0.66 and 0.99, respectively). In contrast, IE(180 degrees Desc) was not correlated to GE or to NE. From a mechanical point of view, during the upstroke, the subject was able to reduce the non-propulsive forces applied by an active muscle contraction, contrary to the downstroke phase. As a consequence, the term 'passive phase', which is currently used to characterize the upstroke phase, seems to be obsolete. The IE(180 degrees Asc) could also explain small variations of GE and NE for a recreational group.

Bidirectional propagation of cold atoms in a “stadium”-shaped magnetic guide

We demonstrate the bidirectional propagation of more than ${10}^{7}\phantom{\rule{0.3em}{0ex}}\mathrm{atoms}$ ${(}^{87}\mathrm{Rb})$ around a ``stadium''-shaped magnetic ring that encloses an area of $10.9\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{2}$, with a flux density exceeding ${10}^{11}\phantom{\rule{0.3em}{0ex}}\text{atom}\phantom{\rule{0.2em}{0ex}}{\text{s}}^{\ensuremath{-}1}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$. Atoms are loaded into the guide from a two-dimensional (and higher) magneto-optical trap at one side of the ``stadium.'' An optical standing wave pulse is applied to increase the propagation velocity of atoms along the waveguide. The atom sample fills the entire ring in $200\phantom{\rule{0.3em}{0ex}}\mathrm{ms}$ when counterpropagating atom sections of the original atom cloud recombine at their initial positions after a full revolution.

Thermoacoustic tissue scanner

A thermoacoustic imaging system including an electromagnetic radiation source for irradiating said tissue to stimulate a thermoacoustic response, a coupling media for acoustically coupling the response to an acoustic sensor array, and an acoustic sensor array. The array comprises sensors arranged on a surface, which is rotatable about an axis to position said sensors in a plurality of positions for detecting the thermoacoustic response. The angular extent of the surface about the axis, subtends an angle that is less than a full revolution, streamlining the device and permitting flexibility in positioning the radiation source and other elements of the device. The source of electromagnetic radiation for irradiating the tissue is a plurality of sources arranged about the tissue and producing synchronized electromagnetic radiation in varying polarizations or phases to irradiate said tissue with electromagnetic radiation of a desired polarization. A thermoacoustic imaging system sized to be held within the human hand is also disclosed.

Monte Carlo simulation and dose distribution of low energy electron irradiation of an apple

The most difficult technical challenge for surface irradiation of fruits and vegetables is the need to achieve a uniform dose over the entire surface of convoluted shapes. The main goal of this research was to calculate the dose distribution produced by low energy electron irradiation of a typical complex shape, an apple, using Monte Carlo simulation. In this study, Monte Carlo simulation was used to determine the dose distribution at the surface of an apple irradiated with e-beam generated by a Van de Graaf accelerator (1–2 MeV). The dose distribution was used to develop the best irradiation angle while rotating an irregularly shaped food material (the apple) for uniform surface irradiation. A software package, Monte Carlo N-particle, was used to simulate an electron beam irradiation with a 1.0, 1.5 and 2.0 MeV sources on an apple. The apple structure was simulated by creating 3-D apple-like shape geometry by joining two spheres of 3.2 cm of radius each. The entire body is centered at the origin and the spheres are centered at −1.2 and 1.2 cm on the y-axis in the z– y-plane. As the apple is tilted towards the source, the dose gets distributed mainly in the front top region of the apple. Likewise, as the apple is tilted against the source, the dose gets distributed primarily in the lower front portion of the apple. A combination irradiation treatment with the axis of the apple tilted 30° against and 30° towards the source irradiation position after one full revolution resulted in the most uniform dose distribution for the three energies source tested. The average dose at the surface of the front of the apple was in the range from 1.2 to 1.6 kGy and 3.6 to 4.0 kGy at the surface of the top and bottom.

New position detectors based on AMR sensors

New angular and linear position detectors for automotive applications have been developed: an absolute linear position detector, a full revolution absolute angular position detector, and a discrete crankshaft position detector. The detectors exploit the capability of anisotropic magnetoresistance (AMR) sensors to sense the direction of a magnetic field, independent of the field strength. This capability gives AMR-based detectors clear cost or tolerance advantages over detectors based on field strength measuring sensors, for instance, inductive sensors, Hall effect sensors, or semiconducting magneto-resistive sensors.

Intuitionism as a (failed) Kuhnian revolution in mathematics

In this paper it is argued, firstly, that Kuhnian revolutions in mathematics are logically possible, in the sense of not being inconsistent with the nature of mathematics; and, secondly, that Kuhnian revolutions are actually possible, in the sense that a Kuhnian paradigm for mathematics can be exhibited which would, if accepted by the mathematical community, produce a full Kuhnian revolution. These two arguments depend on first proving that a shift from a classical conception of mathematics to an intuitionist conception would be incommensurable, that is, that some classical statements, possessing meanings which cannot be preserved in the intuitionist language, would become unintelligible. The vague but intriguing thesis is then tentatively advanced that Kuhnian revolutions are even historically possible, in the sense that only what we might call ‘accidental’ historical factors may have prevented mathematics from undergoing just such a Kuhnian revolution in the early years of the twentieth century.

Kinematic analysis of Toxoplasma gondii motility.

Toxoplasma gondii tachyzoites execute a complex and little understood combination of rapid movements to reach and penetrate human or other animals cells. In the present study, computer-assisted simulation was used to quantitatively analyze the motility of these parasites in three-dimensional space with spatial and temporal resolutions in the micrometer and subsecond ranges. A digital model based on electron-micrographs of a serially sectioned tachyzoite was animated according to a videomicrographed sequence of a characteristic repetitive movement. Keyframe animation defined over 150 frames by a total of 36 kinematic parameters for specific motions, of both the whole model and particular domains, resulted in a real-time life-like simulation of the videorecorded tachyzoite movement. The kinematic values indicate that a full revolution of the model is composed of three half-turns accomplished in nearly 5 s with two phases: a relatively slow 180 degrees tilting with regard to the substratum plane, followed by fast (over 200 degrees/s) spinning almost simultaneous with pivoting around the posterior end, each clockwise and for about 180 degrees. Maximal flexing of the body, as well as bowing and retraction of its anterior end, occur at midway during the tilting phase. An estimated 70 degrees. clockwise torsion of the body seems to precede the spinning-pivoting phase. The results suggest the operation of two basic forces in the motility of T. gondii tachyzoites: (1) a clockwise torque that causes torsion, spinning, and pivoting; and (2) a longitudinal pull that contracts, bends and tilts the parasite. We discuss the possibility that both of these forces might result from the action of an actin-myosin system enveloping the twisted framework of microtubules characteristic of these organisms.

Spatio-temporal sub-harmonic cascade in a non-linear interferometer with a liquid-crystal light valve

A bounded spatio-temporal period-doubling sequence is shown to occur in the Ahkmanov et al. non-linear interferometer. This happens when the pattern is a rotating 2k-armed spiral. First, all arms are identical and the period is the time required for any arm to rotate by the angle 2 pi /2k. As the control parameter increases, the time trace at some location on the pattern displays period doubling as the arms develop progressively distinct spatial modulations. Period 2 behaviour occurs when the nearest patterns similar to arm 'i' are arms 'i+or-2', period 4 behaviour occurs when arm 'i' has arms 'i+or-4' as its nearest similar neighbours, and so on until period 2k when all arms are distinct and the pattern must complete a full revolution for the time series to repeat. Such a cascade is shown to be qualitatively modelled by a mapping.

Foucault pendulum ‘‘wall clock’’

Details are given for the construction of a 70-cm-long Foucault pendulum to be mounted on the wall, and for a simple modification that will make it display local clock time. The possibility of having a Foucault pendulum of such short length is the result of finding new or improved ways of reducing four perturbing effects that become more severe as the length is decreased. They relate to: precession due to ellipticity in the motion, the drive system for maintaining the amplitude, the means of limiting the growth of ellipticity, and the method of gripping the suspending wire at the top. With those improvements, successful Foucault operation was attained in pendulums as short as 15 cm, support to center of bob. Following that severe test, the length for the ‘‘wall clock’’ was set at a conservative 70 cm. At that length it is highly reliable, and accurate to within 2% when timed for the full revolution. Uniformity in rate when comparing different intervals of azimuth is of course less. A simple method of making the pendulum read local time is described. Two clocks, one in the author’s office and one at home, have been in continuous operation for more than ten years.

3D PDC Bit Model Predicts Higher Cutter Loads

Summary Historically, PDC bit modeling has incorporated the assumption that cutter forces are constant for a full revolution of the bit. This assumption places considerable limits on the model's ability to simulate drilling in nonhomogeneous rock and in cases where the bit whirls. Recent studies have shown that cutter damage caused by impact loading is a primary cause of PDC bit failure. These impacts may be caused by both bit whirl and drilling through nonhomogeneous rock. The 3D model presented provides the capability to evaluate cutter loading for both conditions. It shows that the cutter loads for common drilling situations may be as much as 10 times greater than those calculated with previously available 2D models.

The global structure of the annual and semiannual sea surface height variability from Geosat altimeter data

The global structure of the annual and semiannual sea surface height variability is constructed from the first 2 years of the Geosat Exact Repeat Mission (ERM) altimeter data. The GEM‐T2 orbits available for the first 2 years of the ERM have an accuracy of 40 cm RMS. Residual orbit error is modeled as one cycle per orbital revolution and is removed from collinear differences of arcs made of data from one full orbital revolution of the satellite. The error in the Schwiderski M2 tidal model must be estimated due to the fact that the tidal variability aliases to 1.15 cycles per year (cpy), and this frequency is not separable from 1 cpy with the 2 years of data. An estimate of the M2 tidal error is made based on the particular temporal and spatial aliasing of the tide. With this error removed, a least squares fit of sine and cosine waves with annual and semiannual frequencies is made to the time series at every point along the ground track of the satellite. This produces sine and cosine coefficients at the ground track points which are interpolated to a regularly spaced ½° grid over the globe. From the sine and cosine maps, amplitude and phase may be obtained. Interpolation of the sine and cosine coefficients using different spatial scales is done to better observe the large‐scale phase changes and to remove small‐scale noise. Results show the phase relationships between major current systems, large‐scale variations near the equator in the Intertropical Convergence Zone (ITCZ), a 180° phase difference between the northern and southern hemispheres for the annual variability, large‐scale westward propagating waves, and other large‐scale gyre features.

Splitting of Periodic Comets

Among the comets that were observed to break in two or more fragments, only a few of them are periodic. So far the dynamic study of the relative motion of a secondary nucleus with respect to the primary has supposed that a cometary fragment is subject to a small and continuousradialnongravitational force after separation at rest. This force acts against the solar attraction and varies according to an inverse square law. A small impulse at break up may also be invoked in some case. A different approach is followed in this paper when dealing with a fragment of a periodic comet: after separation the motion of a secondary nucleus is characterized by nongravitational forces which vary according to the sameg(r) law currently used for the primary.Results of the study of comets P/Biela and P/du Toit-Hartley show that the motion of their fragments after separation is characterized by nongravitational parameters which are larger than those of the parent bodies. Both fragments lasted for about 2 full revolutions and three returns.

Twenty Years of Speckle Interferometry

The purpose of my talk is to briefly review the results of two decades of astrometric research using the technique of speckle interferometry. Although speckle, invented by Labeyrie in 1970 (Gezari et al. 1972), is the most well–known and widely–used interferometric technique in the visible and near infra-red, it neither the only technique in use, nor was it the first. Karl Schwarzschild made the first interferometric measurements of binary stars in 1895, using the then–new technique of Michelson interferometry and following a suggestion by Michelson himself that his technique was amenable to binary star astrometry. From 1919 to 1921, Anderson (1920) and Merrill (1922) made a series of measurements of Capella and other bright stars, using a Michelson interferometer of 20-foot baseline, mounted on the Mount Wilson 100-inch. These early measurements have definitely stood the test of time. Figure 1 shows a recently calculated orbit of Capella (Bagnuolo & Hartkopf 1989), using data spanning some 250 full revolutions. Anderson and Merrill’s measurements agree beautifully with observations made 7 decades later. As a result, Capella has probably the most accurately known orbit of any visual binary. Orbital elements calculated in 1981 (McAlister 1981) and again 10 years later differ in period by about 14 seconds, or less than 2 parts per million!

Optimal design parameters of the bicycle-rider system for maximal muscle power output

The purpose of this study was to find the optimal values of design parameters for a bicycle-rider system (crank length, pelvic inclination, seat height, and rate of crank rotation) which maximize the power output from muscles of the human lower limb during bicycling. The human lower limb was modelled as a planar system of five rigid bodies connected by four smooth pin joints and driven by seven functional muscle groups. The muscles were assumed to behave according to an adapted form of Hill's equation. The dependence of the average power on the design parameters was examined. The instantaneous power of each muscle group was studied and simultaneous activity of two seemingly antagonistic muscle groups was analyzed. Average peak power for one full pedal revolution was found to be around 1100 W. The upper body position corresponding to this peak power output was slightly reclined, and the pedalling rate was 155 rpm for a nominal crank length of 170 mm.

UHV rotary manipulator with arcsecond resolution for x-ray standing-wave experiments

A UHV-compatible rotary manipulator with arcsecond resolution has been constructed for use in x-ray standing-wave experiments. The manipulator is computer controlled and features two separate stepping motor drives, a ‘‘coarse’’ drive which allows sample rotations in increments of 7 arcsec with full revolution range, and a ‘‘fine’’ drive with a range of 1° and angular increments of 0.9 arcsec. The performance of the manipulator was tested under UHV conditions by recording rocking curves from a Ge(111) two-crystal monochromator in a nondispersive configuration, using Cu Kα radiation from a sealed x-ray tube. Repeated measurements taken over periods of several hours reveal excellent repeatability and precision.

Optimization of planar and spherical function generators as minimum-defect linkages

In this paper, minimum-defect linkages are defined as linkages having a fully rotatable input and a maximum transmission quality. The transmission quality, introduced elsewhere, is defined as the integral, over a full revolution of the input link, of the square of the sine of the transmission angle. The complement of this quantity is defined here as the transmission defect. It is shown here that it can be expressed as a positive-definite quadratic form, which readily leads to a nonlinear least-square formulation of the associated linkage-optimization problem. Moreover, this quadratic form is shown to equal the square of the mean value plus the variance of the cosine of the transmission angle. This leads to the study of a particular class of linkages for which the mean value of the cosine of the transmission angle vanishes. Linkages pertaining to this class are defined as zero-mean linkages. Theorems concerning the mobility of zero-mean linkages are stated and proven. Moreover, guidelines for the design of this class of linkages are given. Transmission-defect minimization is then applied to the design of quick-return planar and spherical mechanisms.

The Military in African Politics. Edited by John W. Harbeson. New York: Praeger, 1987. 208p. $35.95.

Military Rulers in African Politics The Military in the Politics of Succession: Algeria Populist Military Regimes in West Africa Principles and Practices in Nigerian Military Government Ethnicity and the Role of the Military in the People's Republic of Benin Military Rule in the People's Republic of Congo One Full Revolution: The Politics of the Sudanese Military Military Rule and the Quest for a Post-Imperial Ethiopia Bibliography Index

Rotational stimulation disrupts spatial learning in fornix-lesioned rats.

Normal and fornix-lesioned rats were trained to find water in a version of a spatial discrimination task involving the use of a cross maze modified for interspersing rotational stimulation before the start of each trial. The central (cross) portion of the maze rested on a turntable and consisted of a covered start box opening into the intersection of the cross, allowing choice among three covered alleys, each of which led through a black curtain onto a stationary goal arm. The animal could be started in one of three positions (0 degree, 90 degrees, 270 degrees) in relation to the rewarded goal arm. Room cues were not available until after the animal made the choice in the covered tunnel area. A 20-day testing period in which one to ten full revolutions were interspersed before the start of each trial revealed marked differences between normal and fornix-lesioned animals. The overall performance of normal animals improved from 40% correct choices to 85% correct during the testing period. Fornix-lesioned rats showed no significant improvement during the same period. Performance on probe trials in which room cues were made available to the animals during interspersed rotations improved rapidly and was not significantly different between the two groups. The results suggest that adaptation to vestibular system stimulation was required to solve the covered tunnel task in normal rats and that such processes were disrupted in fornix-lesioned rats.

Direct infrared observations of the very low mass object Gliese 623B

A low-mass, probably stellar, companion to the nearby star Gliese 623 has been detected interferometrically at 1.25, 1.65, and 2.2 microns, and its motion has been monitored over more than one full revolution cycle. Detection of this companion confirms a low-amplitude perturbation of the photocenter indicated previously by extensive astrometric observations. The interferometry, together with available astrometric and radial velocity measurements, yields improved orbital elements and the first photometric measurements and mass determinations of the component stars. The indicated luminosity and mass of G1 623B appear inconsistent with stellar models which predict a rapid decline of luminosity with decreasing mass for stars of age 2 Gyr and greater. 21 references.

Comparison of various grazing incidence spectrometer designs based on conical diffraction

A spectrometer design covering the complete beam collected by a telescope system of full revolution was compared with designs covering only a sector of 25% out of the same telescope. We found that the effective area of one sector is practically equal to that of the full beam system. This is due to the difference in polarization effects and to the smaller average value for the grazing angle of the sector systems. We also compared the throughput of a specified full beam system found by our calculations with the throughput published by other authors for the same system. Deviations have been observed ranging from a factor of 0.5 to a factor of 10.