Forward Edge Research Articles

A Biomechanical Analysis of Successful and Unsuccessful Quadruple Salchow Figure Skating Jumps

Introduction: The majority of research on figure skating jumps has been done on the triple Axel, which is the most difficult triple jump (Aleshinsky, 1988; King, 1999). However, male skaters today must be able to perform a ‘quad' to be competitive. One of the ‘quads' being performed is the quad Salchow. This is an edge jump, like the Axel, but performed from a back edge instead of a forward edge. Research on double and triple Axels suggests that rotation, and not height, is one of the most critical variables as compared to a double or single Axel (Aleshinsky, 1988; Albert and Miller, 1996). The purpose of this study was to investigate the characteristics of successful and unsuccessful quadruple Salchow jumps to determined the critical parameters for success. Methods: Data were collected during the 2000 State Farm Figure Skating Championships. Four video cameras (120 fps) were used with a pan and tilt camera system (Peak Performance Technologies, Inc.) to record the quadruple jumps performed at Nationals. Two cameras each were placed on both sides of the rink and were gen-locked. A calibration was done using survey poles placed on the ice surface. Data were manually digitized and then filtered using a low pass filter (6 Hz cutoff). Three dimensional coordinates were calculated using the Peak Motus pan and tilt procedure. These data were analyzed using software written in LabView (National Instruments, Inc.). Only one skater performed quadruple Salchows, from which two successful jumps and two unsuccessful jumps (the skater fell) were analyzed and compared descriptively. Results: In both successful and unsuccessful quad Salchows, the skater completed on average 3.3 revolutions in the air. The successful jumps were 57 degrees further around (preRot) at take-off as compared to the unsuccessful jumps. At landing they were 68 degrees closer to completing the last revolution (LandRot). The skater's moments of inertia about a longitudinal axis through the trunk were 16% smaller at take-off, but his average angular velocities in flight were similar. Approach velocity (Hvapp) was 11% faster for successful jumps, though both vertical velocity at take-off (Vvto), and flight times (T) were similar (Table).Table: Select Characteristics for Quad Salchows (see text for details). PreRot = degrees pre-roated at take-off. Land Rot = degrees short at landing.Discussion: The main differences in the jumps were the greater pre-rotation at take-off (and thus being able to land more fully rotated) and a faster approach speed in the successful jumps. Completing almost 20% more of the final revolution allowed the skater to be properly aligned at landing and to carry speed out of the jump. Having to finish a large proportion (43%) of last rotation on the ice, as was done in the unsuccessful jumps, is hard to control and can result in a fall. In triple Axels, however, better jumps are characterized by more height and less pre-rotation (King, 1997), suggesting a different emphasis for successful quads than for a well completed triple Axel. Acknowledgements: Supported by the United States Olympic Committee and the United States Figure Skating Association.

ITAL]Chandra[/ITAL] Observation of a 300 Kiloparsec Hydrodynamic Instability in the Intergalactic Medium of the Merging Cluster of Galaxies A3667

We present results from the combination of two Chandra pointings of the central region of the cluster of galaxies A3667. From the data analysis of the first pointing, Vikhlinin, Markevitch, and Murray reported the discovery of a prominent cold front that is interpreted as the boundary of a cool gas cloud moving through the hotter ambient gas. They discussed the role of the magnetic fields in maintaining the apparent dynamical stability of the cold front over a wide sector at the forward edge of the moving cloud and in suppressing transport processes across the front. In this Letter, we identify two new features in the X-ray image of A3667: (1) a 300 kpc arclike filamentary X-ray excess extending from the cold gas cloud border into the hotter ambient gas and (2) a similar arclike filamentary X-ray depression that develops inside the gas cloud. Both features are located beyond the sector identified by the cold front and are oriented in a direction perpendicular to the direction of motion. The temperature map suggests that the temperature of the filamentary excess is consistent with that inside the gas cloud, while the temperature of the depression is consistent with that of the ambient gas. We suggest that the observed features represent the first evidence for the development of a large-scale hydrodynamic instability in the cluster atmosphere resulting from a major merger. This result confirms previous claims for the presence of a moving cold gas cloud in the hotter ambient gas. Moreover, it shows that, although the gas mixing is suppressed at the leading edge of the subcluster as a result its magnetic structure, strong turbulent mixing occurs at larger angles toward the direction of motion. We show that this mixing process may favor the deposition of a nonnegligible quantity of thermal energy right in the cluster center, affecting the development of the central cooling flow.

Human Dignity and Human Rights: Thoughts on the Principles of Human-Centered Design

As I walked on the shore of Cape Town to the opening ceremonies of a conference on design in South Africa, I saw through the rain and mist a small sliver of land in the bay. Naively, I asked my host if it was part of the peninsula that extends south of the city or an island. With what, in retrospect, must have been great patience, she quietly explained that it was not “an” island, it was “the” island. I was embarrassed, but I knew immediately what she meant. I spent the rest of the evening thinking about the political prisoners who were held on Robben Island, human rights, and the irony of a conference within sight of Table Bay that seeks to explore the reshaping of South Africa by design. I was helped in these thoughts by the address of the Minister of Education, Dr. Kadir Asmal, who opened the conference by exploring the meaning of design, the need and opportunities for design in South Africa, and, most importantly, the grounding of design in the cultural values and political principles expressed in the new South African Constitution. I have never heard a high government official anywhere in the world speak so insightfully about the new design that is emerging around us as we near the beginning of a new century. Perhaps everyone in the audience was surprised by how quickly and accurately he captured the core of our discipline and turned it back to us for action. Many of his ideas were at the forward edge of our field, and some were further ahead than we are prepared to admit. For example, I believe we all recognized his significant transformation of the old design theme of “form and function” into the new design theme of “form and content.” This is one of the distinguishing marks of new design thinking: not a rejection of function, but a recognition that unless designers grasp the significant content of the products they create, their work will come to little consequence or may even lead to harm in our complex world. I was particularly surprised, however, by Dr. Asmal’s account of the creation—and here he deliberately and significantly used the word “design”—of the South African Constitution. He explained that after deliberation the drafters decided not to model the document on the familiar example of the United States Constitution, with an appended Bill of Rights, but rather to give central importance from the beginning to the concept of human

Formation of electron beams by the interaction of a whistler wave packet with radiation belt electrons

The purpose of this paper is to discuss the properties of electron beams formed by cyclotron interactions between radiation belt electrons and a quasi-monochromatic whistler wave packet from a ground-based VLF transmitter. The beams are formed due to trapping of the electrons at the forward edge of the wave packet, their acceleration inside the wave packet, the escape of the accelerated electrons from the moving backward edge of the wave packet, and their following free motion in an inhomogeneous magnetic field. A combination of these processes provides the main features of the spatial-temporal evolution of the beams which are investigated both analytically and numerically. It is shown that one or two beams can appear at one point at the same time, and that the density of the beams increases during their expansion. Motion of the pumping wave packet in the inhomogeneous magnetic field provides the variations of the initial velocity and position of the beam injection which change the spatial and temporal gradients of the parallel velocity of the beam, in contrast with the case of the pure adiabatic motion of an individual electron. Such a behaviour can be significant for the generation of secondary emissions. Numerical calculations demonstrate a wide variety of the spatio–temporal patterns of the beam parallel velocity depending on the plasma and wave packet parameters. It is shown that the most significant parameters which determine the beam characteristics are the wave packet length about the equator, its group velocity, and the initial energy and pitch angle of the electrons.

Effects of local flow on the heat transfer characteristics of a cowled, finned system

Experimental studies of the local flow and heat transfer characteristics within the finned region of a cowled, annularly finned cylinder are presented. The temperature and local heat fluxes across fin surfaces were measured using thermocouples and Micro-foil™ heat flux sensors. Areas of maximum heat transfer coefficients greater than 60 W/m2K were observed in the forward fin tip and base regions. A local minimum of 12 W/m2K was found in the mid-fin regions behind the finned cylinder. The local flow characteristics with in the finned region were measured using laser Doppler anemometry at an inlet Reynolds number of 4 × 105. Areas of high turbulence intensity and shifting high-velocity zones were found. Correlation between the heat transfer and flow characteristics confirm the existence of boundary layer development, forward edge separation, and root and tip vortices. The application of the cowl system on a finned cylinder leads to a heat transfer enhancement of greater than 29 per cent. Localized fluctuations of the heat flux on the fin surface are also discussed.

Role of decapentaplegic in initiation and progression of the morphogenetic furrow in the developing Drosophila retina.

Morphogenesis in the Drosophila retina initiates at the posterior margin of the eye imaginal disc by an unknown mechanism. Upon initiation, a wave of differentiation, its forward edge marked by the morphogenetic furrow (MF), proceeds anteriorly across the disc. Progression of the MF is driven by hedgehog (hh), expressed by differentiating photoreceptor cells. The TGF-beta homolog encoded by decapentaplegic (dpp) is expressed at the disc's posterior margin prior to initiation and in the furrow, under the control of hh, during MF progression. While dpp has been implicated in eye disc growth and morphogenesis, its precise role in retinal differentiation has not been determined. To address the role of dpp in initiation and progression of retinal differentiation we analyzed the consequences of reduced and increased dpp function during eye development. We find that dpp is not only required for normal MF initiation, but is sufficient to induce ectopic initiation of differentiation. Inappropriate initiation is normally inhibited by wingless (wg). Loss of dpp function is accompanied by expansion of wg expression, while increased dpp function leads to loss of wg transcription. In addition, dpp is required to maintain, and sufficient to induce, its own expression along the disc's margins. We postulate that dpp autoregulation and dpp-mediated inhibition of wg expression are required for the coordinated regulation of furrow initiation and progression. Finally, we show that in the later stages of retinal differentiation, reduction of dpp function leads to an arrest in MF progression.

Power handling of magnetostatic wave resonators

In this paper, an experiment is presented to study a possible power handling enhancement of magnetostatic forward volume wave straight edge resonators. Theoretically, the power range for a linear response of the resonator is expected to be increased by inclining the sample with respect to the dc magnetic bias field direction, and a critical angle can be predicted for suppressing non-linear effects. Actually, it is demonstrated that a compromise has to be reached between the increase in the power handling and the observed decrease in the resonator quality factor.

Thermostability of obliquely magnetized magnetostatic wave straight edge resonators

The frequency shift due to temperature variation in the microwave response of a magnetostatic forward volume wave YIG straight edge resonator in a band-stop configuration filter has been measured. In particular, the effect of the angular variation /spl theta//sub e/ of the dc magnetic bias field H/sub e/ with respect to the film plane on the temperature frequency shift has been experimentally tested, and it has been demonstrated that thermostability improvement can be obtained as a function of /spl theta//sub e/. Moreover, a good agreement between theoretical expectations and experimental findings has been obtained.

Um caso de albinismo em tachã (Chauna Torquata, Oken) (Aves, Anseniformes) ocorrido na estação ecológica do Taím, Rio Grande do Sul, Brasil

It is described herein a case study of albinism in Chauna torquata Oken, 1816 (Southern screamer) occurred at the Ecological Station of Taim, Rio Grande do Sul. Brazil. Screamers are birds of marshes, wet grasslands and forest lagoons. The bill is short and curved, the head is small and slender and the neek rather short. The strong wings are armed with two large, sharp spurs on their forward edge. The feet and legs are fleshy, the lower half of the tibia is bare, and the three long front toes show just a trace of webbing between them, They are often seen walking in pairs on the floating masses of vegetation or in large groups for feeding. The albino specimen described herein was observed feeding in the midst of a group of almost fifty birds. Their plumage was white but their legs and bill were normally red pigmented, and also presented a light grey ring on its neek. It did not represent a case of total albinism, in which pigment should be totally absent.

Association of sferics with a dry intrusion in Meteosat imagery

AbstractA sequence of infrared and water vapour images from Meteosat are used in this short article to display some of the features associated with the development of a North Atlantic cyclone. Lightning reports are shown in conjunction with the imagery to reveal a connection between the formation of thunderstorms and a region of dry air seen in the water vapour pictures. These thunderstorms break out on the leading edge of this dry air near the low centre and along the forward edge of the associated trailing cold front.

Multimedia: gateway to the next millennium

Part 1 Multimedia defined - market sectors, dimensions and directions, Robert Aston and Stan Klein: defining multimedia market sectors, end users, revenues industry turf wars interactive TV - more than entertainment conclusion. Part 2 Multimedia and the phone companies, Roger Fetterman the cable industry versus the telecos multimedia and interactive television industry trends and the consumer. Part 3 Reinventing Hollywood - creative approaches to new media production, Joyce Schwartz: background overview of activities and trends current Hollywood multimedia activities television network/syndication endeavours Interactive Network, Inc. independent producers/developers summary of trends. Part 4 Broadcasting and multimedia - operations, applications, operations, Robert Yadon: broadcast multimedia opportunities/applications NBC desktop news CD-based interactive projects internal station operations LANs, stored graphics and ISDN. Part 5 Intellectual property and multimedia - legal issues in the new media world, Mark Radcliffe: overview of copyright issues ownership compilations hypothetical multimedia work film clips and videos music conclusions. Part 6 Virtual reality - the forward edge of multimedia, Dr Frank Biocca and Kenneth Meyer: VR - not just a medium - a destination industry programmer and consumer activity state-of-the-art - developments to 2000 and beyond 3D viewing - head-mounted visual displays coordinating the physical and virtual worlds - input devices. Part 7 Multimedia and future media - 2000 and beyond, David Rosen: multimedia's Achilles heel product marketing and retailing long term directions the coarse for television new media for a new millennium.

Effect of ground and ceiling planes on shape of energized wakes

Energized wakes expelled by devices like thrust augmentors, propellers and rotors are studied theoretically in order to explore how their shape changes as they interact with ground and ceiling planes. It is found that when the airstream is stationary and the vehicle in hover, the presence of a ceiling plane causes an energized wake to constrict even more than when in an unbounded medium. The presence of a ground plane is found to cause the wake to constrict less than in free space. The computations also show that the vortex sheets first move inward before moving downward. Along their trajectory, the vortex sheets that separate the energized fluid from the ambient fluid have a nearly constant strength and velocity which indicates that the velocity just inside the wake is approximately constant. When a velocity is given to the wind tunnel airstream, the forward edge of the wake first rises and then descends so that it spends more time in the vicinity of the actuator disk. Implications of these results on measurements obtained in wind tunnels are discussed.

Motor case-to-insulation unbond repair accept/reject criterion

As the 1986 failure of a Titan 34D launch vehicle was linked directly to an insulation unbond of a solid rocket motor, a comprehensive nondestructive evaluation of bondline integrity was implemented by the motor manufacturer. Unbonds at the insulation-case interface were discovered in several production units of the Titan 34D solid rocker motors along the forward edge of the motor segment. These unbonds were repaired by machining a J-shaped groove in the insulation edge area. In order to assure its flightworthiness, the J-repairs were subjected to acceptance proof tests. Detailed finite element stress analyses were conducted to develop an accept/ reject criterion for use in J-repair proof tests. The proof-test criterion, established in terms of required prooftest loads and test-tool displacements, accounts for the effects of temperature, time-to-load, and J-repair size. The analyses indicate that J-repairs up to 0.25 in. deep can be accepted by the insulation bondline proof test. For a larger repair, however, an additional proof test is required after the J-repair is filled with filler material.

End blown flute with standard keying

An end-blown flute comprising a hollow tube open at both ends with an embouchure at the upper end of the tube to provide an end-blown free air-reed. The tube has at least 13 tone holes through the side wall thereof, the holes being particularly spaced from the bottom of the tube so that keys can be mounted in the tube in the same pattern as on a standard transverse flute and so that the end blown flute can be played with the same fingering system used with a standard transverse flute. The embouchure has a U-shaped opening which opening which opens into the upper end of the flute and also exposes the upper forward edge of the flute tube, making it easier for the player to get into the third register.

Sedimentary Fracturing around Rapidly Moving Salt Sheets

High-speed motion through sediments of salt sheets at various rates (10-20 km/Ma), depths, and salt sheet thicknesses are presented in this study. Mohr's criterion for failure is used to examine the domains of primary and secondary fracturing surrounding the mobile salt sheets. Sediment structures are also examined. Three sets of numerical examples of initiation of fracturing and/or faulting in formations around a rapidly moving salt sheet are illustrated. It is shown that (1) the higher the rate of salt motion, the larger the range of fracturing; and (2) the domain of fracturing around the sale body depends on the salt size and sediment properties as well as on the salt speed. Generally, the fracturing domain extends to as far as 2-4 km in the vertical and to about 3-5 km in the lateral direction around the forward edge' of the salt sheet.

Generation and propagation of African squall lines

AbstractA study of squall lines affecting Minna, Nigeria during 1974–1976 emphasizes two particular aspects of their dynamics: that a strong jet around 650 mb is essential for their development, and that the forward edge of the squall line moves slightly faster than the maximum jet speed. A linear model of the squall line as a superposition of normal modes of an unstably stratified sheared flow sheds light on these observations. If the flow profile has a mid‐level maximum, constructive interference of normal modes gives rise to an expanding circle of convection with an arc front moving slightly faster than the maximum mean flow speed, followed by individual cells. If, however, shear is unidirectional, there is no arc front, and a line of cells is formed moving at the middle level mean flow speed. These two cases are suggested as models for tropical and mid‐latitude squall lines respectively, while a further case provides a possible model for storm‐splitting.

Generation and propagation of African squall lines

A study of squall lines affecting Minna, Nigeria during 1974–1976 emphasizes two particular aspects of their dynamics: that a strong jet around 650 mb is essential for their development, and that the forward edge of the squall line moves slightly faster than the maximum jet speed. A linear model of the squall line as a superposition of normal modes of an unstably stratified sheared flow sheds light on these observations. If the flow profile has a mid-level maximum, constructive interference of normal modes gives rise to an expanding circle of convection with an arc front moving slightly faster than the maximum mean flow speed, followed by individual cells. If, however, shear is unidirectional, there is no arc front, and a line of cells is formed moving at the middle level mean flow speed. These two cases are suggested as models for tropical and mid-latitude squall lines respectively, while a further case provides a possible model for storm-splitting.

Record cueing apparatus for turntable tone arm

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Dynamic Measurements of the Current Distribution in the Foot of an ARC Propagating Along the Surface of an Electrotype

Measurements of the arc current distribution obtained for pertinent flashover conditions are reported. A new experimental technique for measuring the distribution of the current in the foot of the arc as it progresses at the surface of an electrolyte is described. Results indicate a sharp current density gradient at the forward edge of the arc foot and a low gradient in a region extending a few centimeters behind. These results are compatible with conformal mapping of the current streamlines, provided that account be taken of a current in the electrolyte which flows parallel to the arc current. This parallel current was measured, in the electrolyte throughout the entire length of the arc during flashover. A propagation model is also proposed which stresses the importance of this asymmetrical shape of the current distribution in the continuous regeneration of the arc channel in the forward direction. An average current density of ~2 A/cm2 was measured, although a peak current density of ~30A/cm2 was measured in the arc core. These results and the formulation of the proposed model are compared with those reported in the literature.

Phonograph cartridge replaceable stylus assembly

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