54,721 research outputs found

    Fish and freshwater crayfish in streams in the Cape Naturaliste region and Wilyabrup Brook

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    Design concepts for low-cost composite turbofan engine frame

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    Design concepts for low cost, lightweight composite engine frames were applied to the design requirements for the frame of a commercial, high bypass engine. Four alternative composite frame design concepts identified which consisted of generic type components and subcomponents that could be adapted to use in different locations in the engine and the different engine sizes. A variety of materials and manufacturing methods were projected with a goal for the lowest number of parts at the lowest possible cost. After a preliminary evaluation of all four frame concepts, two designs were selected for an extended design and evaluation which narrowed the final selection down to one frame that was significantly lower in cost and slighty lighter than the other frame. An implementation plan for this lowest cost frame is projected for future development and includes prospects for reducing its weight with proposed unproven, innovative fabrication techniques

    The effect of movement variability on putting proficiency during the golf putting stroke

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    Movement variability has been considered important to execute an effective golf swing yet is comparatively unexplored regarding the golf putt. Movement variability could potentially be important considering the small margins of error between a successful and a missed putt. The aim of this study was to assess whether variability of body segment rotations influence putting performance (ball kinematic measures). Eight golfers (handicap range 0–10) performed a 3.2 m level putt wearing retro-reflective markers which were tracked using a three-dimensional motion analysis system sampling at 120 Hz. Ball roll kinematics were recorded using Quintic Ball Roll launch monitor. Movement (segment) variability was calculated based on a scalene ellipsoid volume concept and correlated with the coefficient of variation of ball kinematics. Statistical analysis showed no significant relationships between segment variability and putting proficiency. One significant relationship was identified between left forearm variability and horizontal launch angle, but this did not result in deficits in putting success. Results show that performance variability in the backswing and downswing is not related to putting proficiency or the majority of ball roll measures. Differing strategies may exist where certain golfers may have more fluid movement patterns thereby effectively utilising variability of movement. Therefore, golf instructors should consider movement variability when coaching the golf putt

    Spatial variation of iron abundance in the high speed solar wind, 1972 to 1976

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    The Fe/H ratios in the peaks of high speed streams (HSS) during the decline of Solar Cycle 20 and the following minimum (October 1972-December 1976) were analyzed. The response of the 50-200 keV ion channel of the APL/JHU energetic particle experiment (EPE) on IMP-7 and 8 to solar wind iron ions at high solar wind speeds and Fe measurements were compared with solar wind H and He parameters from the Los Alamos National Laboratory (LANL) instruments on the same spacecraft. In general, the Fe distribution parameters (bulk velocity, flow direction, temperature) are found to be similar to the LANL He parameters. Although the average Fe/H ratio in many steady HSS peaks agrees within observational uncertainties with the nominal coronal ratio of 4.7 x 10(-5), abundance variations of a factor of up to 6 are obtained across a given coronal-hole associated HSS. Over the period 1973-1976, a steady decrease in the average quiet-time Fe/H ratio by a factor of about 4 is measured on both IMP-7 and 8

    Reliability of an experimental method to analyse the impact point on a golf ball during putting

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    This study aimed to examine the reliability of an experimental method identifying the location of the impact point on a golf ball during putting. Forty trials were completed using a mechanical putting robot set to reproduce a putt of 3.2 m, with four different putter-ball combinations. After locating the centre of the dimple pattern (centroid) the following variables were tested; distance of the impact point from the centroid, angle of the impact point from the centroid and distance of the impact point from the centroid derived from the X, Y coordinates. Good to excellent reliability was demonstrated in all impact variables reflected in very strong relative (ICC = 0.98–1.00) and absolute reliability (SEM% = 0.9–4.3%). The highest SEM% observed was 7% for the angle of the impact point from the centroid. In conclusion, the experimental method was shown to be reliable at locating the centroid location of a golf ball, therefore allowing for the identification of the point of impact with the putter head and is suitable for use in subsequent studies

    Microborings in mid Cretaceous fish teeth

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    Fish teeth and other remains from the British Cretaceous contain abundant evidence for post-mortem colonization by endolithic organisms. The borings are here recognised as occurring in three morphotypes, including a flask-shaped form not previously recorded. There is strong evidence to suggest that each of these boring types shows a strong preference for a particular substrate histology. The damage and destruction of vertebrate remains by microborings is here considered to exert a major taphonomic control on microvertebrate assemblages. The relationships between the intensity of colonization of vertebrate material by endolithic organisms and palaeoenvironment have implications for using these bone microborings as palaeoenvironmental indicators

    Entropy "floor" and effervescent heating of intracluster gas

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    Recent X-ray observations of clusters of galaxies have shown that the entropy of the intracluster medium (ICM), even at radii as large as half the virial radius, is higher than that expected from gravitational processes alone. This is thought to be the result of nongravitational processes influencing the physical state of the ICM. In this paper, we investigate whether heating by a central AGN can explain the distribution of excess entropy as a function of radius. The AGN is assumed to inject buoyant bubbles into the ICM, which heat the ambient medium by doing pdV work as they rise and expand. Several authors have suggested that this "effervescent heating" mechanism could allow the central regions of clusters to avoid the ``cooling catastrophe''. Here we study the effect of effervescent heating at large radii. Our calculations show that such a heating mechanism is able to solve the entropy problem. The only free parameters of the model are the time-averaged luminosity and the AGN lifetime. The results are mainly sensitive to the total energy injected into the cluster. Our model predicts that the total energy injected by AGN should be roughly proportional to the cluster mass. The expected correlation is consistent with a linear relation between the mass of the central black hole(s) and the mass of the cluster, which is reminiscent of the Magorrian relation between the black hole and bulge mass.Comment: accepted for Ap

    Oncoming Social Change

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