DIFFERENCES BETWEEN JUMPING AND SOMERSAULTING FROM A DIVING SPRINGBOARD: A SIMULATION STUDY

Maximum-height jumping and jumping for maximizing backward somersault rotations are simulated. The springboard is modeled by a rigid bar with point mass on the tip and a rotational spring on the other hinged end. The planar 4-segment human model is driven by torque actuators at the ankle, knee, and hip. Movement simulation begins from a balanced initial posture and stops at jump takeoff. The objective is to find joint torque activation patterns during board contact so that jump height or the number of backward rotations in flight (determined by takeoff kinematics) is maximized. Kinematic differences between jumps maximizing backward rotations and jumps maximizing height lie mainly in reduced knee angular velocity and consequently bent knees at takeoff. In addition, more significant hip f1exion torque/activation is found in jumps maximizing rotations than that in maximum-height jumps. With reasonable model assumption, this kind of information may be useful for athletic training

Validation of a laboratory method for evaluating dynamic properties of reconstructed equine racetrack surfaces.

BackgroundRacetrack surface is a risk factor for racehorse injuries and fatalities. Current research indicates that race surface mechanical properties may be influenced by material composition, moisture content, temperature, and maintenance. Race surface mechanical testing in a controlled laboratory setting would allow for objective evaluation of dynamic properties of surface and factors that affect surface behavior.ObjectiveTo develop a method for reconstruction of race surfaces in the laboratory and validate the method by comparison with racetrack measurements of dynamic surface properties.MethodsTrack-testing device (TTD) impact tests were conducted to simulate equine hoof impact on dirt and synthetic race surfaces; tests were performed both in situ (racetrack) and using laboratory reconstructions of harvested surface materials. Clegg Hammer in situ measurements were used to guide surface reconstruction in the laboratory. Dynamic surface properties were compared between in situ and laboratory settings. Relationships between racetrack TTD and Clegg Hammer measurements were analyzed using stepwise multiple linear regression.ResultsMost dynamic surface property setting differences (racetrack-laboratory) were small relative to surface material type differences (dirt-synthetic). Clegg Hammer measurements were more strongly correlated with TTD measurements on the synthetic surface than the dirt surface. On the dirt surface, Clegg Hammer decelerations were negatively correlated with TTD forces.ConclusionsLaboratory reconstruction of racetrack surfaces guided by Clegg Hammer measurements yielded TTD impact measurements similar to in situ values. The negative correlation between TTD and Clegg Hammer measurements confirms the importance of instrument mass when drawing conclusions from testing results. Lighter impact devices may be less appropriate for assessing dynamic surface properties compared to testing equipment designed to simulate hoof impact (TTD).Potential relevanceDynamic impact properties of race surfaces can be evaluated in a laboratory setting, allowing for further study of factors affecting surface behavior under controlled conditions

Junior Surface Warfare Officer retention

The purpose of this thesis is to identify factors that lead to resignation of Junior Surface Warfare Officers (SWO) and to develop an hedonic model of junior SWO turnover. The first source of data was a survey of active- duty, junior SWOs currently serving aboard ships. The second source of data was a survey of 0-3 SWOs who are currently drilling in the Naval Reserves. Results of the two surveys were compared to identify differing levels of satisfaction with the active-duty Navy. The reservists also compared their satisfaction between the active-duty Navy and their current civilian employment Civilian salary levels were obtained from the reservists and their spouses to determine the pay differential between the Navy and civilian jobs for former junior SWOs. A regression model found three factors to have significant power in explaining civilian pay: years since leaving active duty, employment status, and comparative work stress between civilian employment and the active-duty Navy. SWOs with full-time employment who experienced the greatest reductions in pay also experienced the greatest reduction in work Stress. Junior SWOs experienced, on average, a 20 percent pay cut after leaving active duty. Pay returned to its pre-departure level in 2 to three yearshttp://archive.org/details/juniorsurfacewar00dumoLieutenant, United States NavyApproved for public release; distribution is unlimited

Lick Northern Proper Motion Program. III. Lick NPM2 Catalog

The Lick Northern Proper Motion (NPM) program, a two-epoch (1947-1988) photographic survey of the northern two-thirds of the sky (Dec. > -23 deg), has measured absolute proper motions, on an inertial system defined by distant galaxies, for 380,000 stars from 8 <B < 18. The 1993 NPM1 Catalog contains 148,940 stars in 899 fields outside the Milky Way's zone of avoidance. The 2003 NPM2 Catalog contains 232,062 stars in the remaining 347 NPM fields near the plane of the Milky Way. This paper describes the NPM2 star selection, plate measurements, astrometric and photometric data reductions, and catalog compilation. The NPM2 Catalog contains 120,000 faint (B > 14) anonymous stars for astrometry and galactic studies, 92,000 bright (B < 14) positional reference stars, and 35,000 special stars chosen for astrophysical interest. The NPM2 proper motions are on the ICRS system, via Tycho-2 stars, to an accuracy of 0.5 mas/yr in each field. RMS proper motion precision is 6 mas/yr. Positional errors average 80 mas at the mean plate epoch 1968, and 200 mas at the NPM2 catalog epoch 2000. NPM2 photographic photometry errors average 0.18 mag in B, and 0.20 mag in B-V. The NPM2 Catalog and the updated (to J2000) NPM1 Catalog are available at the CDS Strasbourg data center and on the NPM WWW site (http://www.ucolick.org/~npm). The NPM2 Catalog completes the Lick Northern Proper Motion program after a half-century of work by three generations of Lick Observatory astronomers. The NPM Catalogs will serve as a database for research in galactic structure, stellar kinematics, and astrometry.Comment: 44 pages, 6 figures, accepted for publication in September 2004 Astronomical Journa

Kinematic Control of the Inertiality of the System of Tycho-2 and UCAC2 Stellar Proper Motions

Based on the Ogorodnikov-Milne model, we analyze the proper motions of Tycho-2 and UCAC2 stars. We have established that the model component that describes the rotation of all stars under consideration around the Galactic y axis differs significantly from zero at various magnitudes. We interpret this rotation found using the most distant stars as a residual rotation of the ICRS/Tycho-2 system relative to the inertial reference frame. For the most distant ($d\approx900$ pc) Tycho-2 and UCAC2 stars, the mean rotation around the Galactic y axis has been found to be $M_{13}=-0.37\pm0.04$ mas yr$^{-1}$. The proper motions of UCAC2 stars with magnitudes in the range $12-15^m$ are shown to be distorted appreciably by the magnitude equation in $\mu_\alpha\cos\delta$, which has the strongest effect for northern-sky stars with a coefficient of $-0.60\pm0.05$ mas yr$^{-1}$ mag$^{-1}$. We have detected no significant effect of the magnitude equation in the proper motions of UCAC2 stars brighter than $\approx11^m$.Comment: 15 pages, 6 figure

State-of-the-art in product service-systems

A Product Service-System (PSS) is an integrated combination of products and services. This western concept embraces a service-led competitive strategy, environmental sustainability, and the basis to differentiate from competitors who simply offer lower priced products. This paper aims to report the state-of-the-art of PSS research by presenting a clinical review of literature currently available on this topic. The literature is classified and the major outcomes of each study are addressed and analysed. On this basis, this paper defines the PSS concept, reports on its origin and features, gives examples of applications along with potential benefits and barriers to adoption, summarises available tools and methodologies, and identifies future research challenges

Differential atrial performance at rest and exercise in athletes: Potential trigger for developing atrial dysfunction?

International audienc

Correction: Validation of a Laboratory Method for Evaluating Dynamic Properties of Reconstructed Equine Racetrack Surfaces.

[This corrects the article DOI: 10.1371/journal.pone.0050534.]

Long-term cardiac assessment in a sample of adolescent-onset anorexia nervosa

Background: High mortality rates have been reported in patients with anorexia nervosa, mainly due to cardiovascular alterations. The purpose of the present study was to assess cardiac structural and functional abnormalities some 20 years after initial treatment in a sample of adolescent-onset anorexia nervosa (A-AN) and to compare them with matched healthy controls (HC). Methods: A sample of 29 women diagnosed and treated for AN during adolescence (A-AN) were assessed more than 20 years later. A complete cardiac evaluation was carried out including an electrocardiogram (ECG) and a standard 2D echocardiography. Thirty matched HC were also assessed. Results: In the A-AN group, four subjects had a body mass index lower than 18.5 and met full DSM 5 criteria for AN at follow-up (Low-Weight group). They were compared with the rest of the sample (n = 25) who had normalized their weight (Normal-Weight group), though some still showed some eating disorder symptoms. Both groups were compared with the HC group. Subjects in the Low-Weight group presented statistically significant decreases in the left ventricular end-diastolic and left atrium dimensions and left ventricular mass in comparison with the Normal-Weight group and the HC. No other differences in cardiac parameters were found between groups. Conclusions: Echocardiographic and ECG parameters of adults who had presented A-AN twenty years earlier and currently maintained normal weight were similar to those of HC who had never been treated or diagnosed with AN. Adult subjects with A-AN who still had low weight in the long term present certain cardiac abnormalities similar to those seen in short-lasting disease. More studies are needed to confirm these results in a larger sample