120,005 research outputs found
COMPARISON OF PUTTING KINEMATICS WHEN USING A TRADITIONAL BLADE PUTTER AND A PUTTER PROTOTYPE
Get PDFINTRODUCTION This study examined the effectiveness of a golf putter prototype and a traditional blade putter on the joint action necessary to complete a medium distance putt. A kinematic analysis of the upper body joints and torso actions was performed to determine if the putting technique utilized with the experimental style putter could reduce the joint action variability needed for the execution of a putt. METHODS Video graphic records were taken from a frontal and a 45 degree side view of 6 experienced golfers performing putts with a conventional and an experimental putter. This blade redesign resulted in the golfers supporting the golf club shaft along the anterior surface of their arm while crouched and facing the cup. This repositioning permitted the sighting of the cup with a frontal view rather than the traditional tilted side view. The subjects were permitted practice trials until they felt comfortable using each putter. Three putts with each putter from the same distance and position from the cup were performed oudoors at a golf club in California and videotaped at the rate of 60 fields per second. A 3-D reference cube using 11 fiducial points was placed in the field of view of both cameras simultaneously in order to convert the video images to real life scale. The third trial using each putter was selected for kinematic analysis and the camera view from each videotape was digitized using an Ariel MAS performance analysis system. Twenty-three data points were digitized and the 2 camera views were synchronized by identifying the ball contact frame and transformed using DLT and coordinates were smoothed using quentic spline with an error value of 2. The 3-D ROMs of the shoulder, elbow, wrist and torso and putting stroke displacement were calculated for the 3rd trial using each putter. RESULTS Related t-tests were performed on the ROM data and putting stroke displacements for the two styles of putter. The traditional putting techniques exhibited 15.4 deg of flexion at the shoulder, 6.8 and 8.0 deg ROMs at the elbow and wrist joints. The new putter design afforded 9.9, 3.5, and 4.4 deg ROMs (flexionlextension) in the shoulder, elbow, and wrist. The traditional putter utilized a total of 30.1 deg ROM in the upper body while the experimental putter exhibited a significant (p =. 10) different total ROM of 17.8 deg. The traditional putter needed. 4.4 deg. Of spinal rotation while a significantly smaller (p =. 033) amount of torso rotation 2.9 deg was needed when putting with the new putter. A putting stroke displacement of 14.7 cm and 11.0 cm was found for the traditional and expdmental putter (p =. 022). CONCLUSIONS The new putter design utilized 59% of the putting motion required by a traditional putting technique. This smaller ROM required to complete the forwardhackward movement would indicate that the new putter design produced a more efficient putting stroke to push the ball while reducing the joint ROM variability and likelihood for erro
The twelfth-century Arthur
No full textKing Arthur came into his own in the twelfth century. Around 1135 he acquired a biographer, Geoffrey of Monmouth, and a few decades later a champion poet, Chrétien de Troyes, the pioneer of Arthurian romance. The fame of both these writers, in their own lifetime and beyond, amply justifies their status as the fathers of Arthurian literature. Its mother was an oral tradition about which we know much less. Not many fossils survive, but those that do are so varied and widespread as to leave us in no doubt about the vigour of the popular tradition on which Geoffrey and Chrétien grafted their invention.</p
Sterile neutrino models and nonminimal cosmologies
Get PDFCosmological measurements are affected by the energy density of massive neutrinos. We extend here a recent analysis of current cosmological data to nonminimal cosmologies. Several possible scenarios are examined: a constant w≠−1 dark energy equation of state, a nonflat universe, a time-varying dark energy component and coupled dark matter-dark energy universes or modified gravity scenarios. When considering cosmological data only, (3+2) massive neutrino models with ∼0.5 eV sterile species are allowed at 95% confidence level. This scenario has been shown to reconcile reactor, LSND and MiniBooNE positive signals with null results from other searches. Big bang nucleosynthesis bounds could compromise the viability of (3+2) models if the two sterile species are fully thermalized states at decoupling
Histoire universelle depuis le commencement du monde ... traduite de l´anglois d´une société de gens de lettres; tome quatrieme, contenant l´histoire de Persa ... des Scyther ...; et l´histoire fabulense & héroique des Royaumes de Sicyone...& de quelques autres Royaumes moins confidérable; avec l´histoire d´Athens & celle des lacedomoniens du monde jusqu´a present.
No full textSing.: *4, A-4R4, 4S2Port. a dos tintas con grab. calc.: "C. de Putter fecit 1742"Apostillas marginalesEn cab. de *2, esc. calcLas h. de grab. calc. son mapas relativos al textosLas h. de map. grab. calc. pleg. entre p. 102-103, 172-173 y 258-25
Constraints on massive sterile neutrino species from current and future cosmological data
Get PDFSterile massive neutrinos are a natural extension of the standard model of elementary particles. The energy density of the extra sterile massive states affects cosmological measurements in an analogous way to that of active neutrino species. We perform here an analysis of current cosmological data and derive bounds on the masses of the active and the sterile neutrino states, as well as on the number of sterile states. The so-called (3 + 2) models, with three sub-eV active massive neutrinos plus two sub-eV massive sterile species, is well within the 95% CL allowed regions when considering cosmological data only. If the two extra sterile states have thermal abundances at decoupling, big bang nucleosynthesis bounds compromise the viability of (3 + 2) models. Forecasts from future cosmological data on the active and sterile neutrino parameters are also presented. Independent measurements of the neutrino mass from tritium beta-decay experiments and of the Hubble constant could shed light on sub-eV massive sterile neutrino scenarios
Numerical analysis of a 3-D printed porous trailing edge for broadband noise reduction
Get PDFLattice Boltzmann simulations were carried out to investigate the noise mitigation mechanisms of a 3-D printed porous trailing-edge insert, elucidating the link between noise reduction and material permeability. The porous insert is based on a unit cell resembling a lattice of diamond atoms. It replaces the last 20 % chord of a NACA 0018 at zero angle-of-attack. A partially blocked insert is considered by adding a solid partition between 84 % and 96 % of the aerofoil chord. The regular porous insert achieves a substantial noise reduction at low frequencies, although a slight noise increase is found at high frequencies. The partially blocked porous insert exhibits a lower noise reduction level, but the noise emission at mid-to-high frequency is slightly affected. The segment of the porous insert near the tip plays a dominant role in promoting noise mitigation, whereas the solid-porous junction contributes, in addition to the rough surface, towards the high-frequency excess noise. The current study demonstrates the existence of an entrance length associated with the porous material geometry, which is linked to the pressure release process that is responsible for promoting noise mitigation. This process is characterised by the aerodynamic interaction between pressure fluctuations across the porous medium, which is found at locations where the porous insert thickness is less than twice the entrance length. Present results also suggest that the noise attenuation level is related to both the chordwise extent of the porous insert and the streamwise turbulent length scale. The porous inserts also cause a slight drag increase compared to their solid counterpart. Wind Energ
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
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