Motion Analysis of a Back Handspring

Purpose: The purpose of this study was to analyze the joint angles and segmental motion of gymnasts during a back handspring in a tumbling series. The difference in lower extremity motion of the individual gymnasts with different levels of experience was compared. Subjects: 13 gymnasts were recruited by gymnastics coaches at Red River Valley Gymnastics. Only subjects with qualifications of being competitive in USA Gymnastics program, varying in levels 5-10, were included. Subjects were required to be able to perform a tumbling series consisting of a round off, a back handspring, and a back tuck-salto on a floor exercise mat independently and in a safe manner. Instrumentation: An eight camera, Vicon Motion System was used for the motion capture and the Vicon Workstation and Polygon 3.0 software was used for analysis and the generation of the reports. Procedure: Prior to beginning the trials, each subject completed a warm-up, followed by a stretching routine. Thirty five reflective markers were placed on the specific bony prominences required by the computer modeling program. Each subject performed up to five trials of the tumbling series with up to a five minute rest period between each trial. Data Analysis: A side view picture was obtained of the initial contact and the second contact of the lower extremities on the floor from the best trial of each subject. The pictures were analyzed qualitatively for the anterior and posterior relationship of the hip, knee, and ankle joint to one other, and to the different levels of the gymnasts. Results and Discussion: In general the higher the level of the gymnast, the more ideal the relationship between the lower extremity segments. The more ideal relationship offered the gymnast better control and ability to obtain the desired motion to progress into the next skill being performed. The middle and lower level athlete\u27s segmental relationships were such that there was not as much control which probably leads to unnecessary body motions, increasing muscle activity, and thus decreasing desired motion to progress into the next skill being performed. In general, the higher level gymnast\u27s body position was closer to the ideal for receiving a higher score by gymnastics judges and the middle and lower level gymnasts had body positions that would normally relate to a lower score. Conclusion and Clinical Implication: It was shown that the upper level gymnasts tended to have hip, knee and ankle positions, relative to each other, that were closest to ideal as compared to the middle and lower level gymnasts. It was also shown that motion analysis can be effective in developing a teaching tool for coaches to promote ideal technique

HST/STIS Ultraviolet Imaging of Polar Aurora on Ganymede

We report new observations of the spectrum of Ganymede in the spectral range 1160 - 1720 A made with the Space Telescope Imaging Spectrograph (STIS) on HST on 1998 October 30. The observations were undertaken to locate the regions of the atomic oxygen emissions at 1304 and 1356 A, previously observed with the GHRS on HST, that Hall et al. (1998) claimed indicated the presence of polar aurorae on Ganymede. The use of the 2" wide STIS slit, slightly wider than the disk diameter of Ganymede, produced objective spectra with images of the two oxygen emissions clearly separated. The OI emissions appear in both hemispheres, at latitudes above 40 degrees, in accordance with recent Galileo magnetometer data that indicate the presence of an intrinsic magnetic field such that Jovian magnetic field lines are linked to the surface of Ganymede only at high latitudes. Both the brightness and relative north-south intensity of the emissions varied considerably over the four contiguous orbits (5.5 hours) of observation, presumably due to the changing Jovian plasma environment at Ganymede. However, the observed longitudinal non-uniformity in the emission brightness at high latitudes, particularly in the southern hemisphere, and the lack of pronounced limb brightening near the poles are difficult to understand with current models. In addition to observed solar HI Lyman-alpha reflected from the disk, extended Lyman-alpha emission resonantly scattered from a hydrogen exosphere is detected out to beyond two Ganymede radii from the limb, and its brightness is consistent with the Galileo UVS measurements of Barth et al. (1997).Comment: 7 pages, 4 figures, accepted for publication in ApJ, June 1, 200

Lyman‐α imaging of the SO 2 distribution on Io

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94916/1/grl12620.pd

Brain iron accumulation in unexplained fetal and infant death victims with smoker mothers-The possible involvement of maternal methemoglobinemia

<p>Abstract</p> <p>Background</p> <p>Iron is involved in important vital functions as an essential component of the oxygen-transporting heme mechanism. In this study we aimed to evaluate whether oxidative metabolites from maternal cigarette smoke could affect iron homeostasis in the brain of victims of sudden unexplained fetal and infant death, maybe through the induction of maternal hemoglobin damage, such as in case of methemoglobinemia.</p> <p>Methods</p> <p>Histochemical investigations by Prussian blue reaction were made on brain nonheme ferric iron deposits, gaining detailed data on their localization in the brainstem and cerebellum of victims of sudden death and controls. The Gless and Marsland's modification of Bielschowsky's was used to identify neuronal cell bodies and neurofilaments.</p> <p>Results</p> <p>Our approach highlighted accumulations of blue granulations, indicative of iron positive reactions, in the brainstem and cerebellum of 33% of victims of sudden death and in none of the control group. The modified Bielschowsky's method confirmed that the cells with iron accumulations were neuronal cells.</p> <p>Conclusions</p> <p>We propose that the free iron deposition in the brain of sudden fetal and infant death victims could be a catabolic product of maternal methemoglobinemia, a biomarker of oxidative stress likely due to nicotine absorption.</p

Will the Public's Health Fall Victim to the Home Foreclosure Epidemic?

Gary Bennett and colleagues discuss the ways in which the dramatic rise in home foreclosures, particularly in the US, may have health consequences

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Establishing ecological reference conditions and tracking post-application effectiveness of lanthanum-saturated bentonite clay (Phoslock®) for reducing phosphorus in aquatic systems: an applied paleolimnological approach

nnovative management strategies for nutrient enrichment of freshwater are important in the face of this increasing global problem, however many strategies are not assessed over long enough time periods to establish effectiveness. Paleolimnological techniques using diatoms as biological indicators were utilized to establish ecological reference conditions, environmental variation, and the effectiveness of lanthanum-saturated bentonite clay (brand name: Phoslock®) applied to reduce water column phosphorus (P) concentrations in four waterbodies in Ontario, Canada, and eastern Australia. In sediment cores from the two Canadian sites, there were short-lived changes to diatom assemblages, relative to inferred background conditions, and a temporary reduction in both measured and diatom-inferred total phosphorus (TP) before returning to pre-application conditions (particularly in the urban stormwater management pond which has a high flushing rate and responds rapidly to precipitation and surface run-off). The two Australian sites (a sewage treatment pond and a shallow recreational lake), recorded no reduction in diatom-inferred TP. Based on our pre-application environmental reconstruction, changes to the diatom assemblages and diatom-inferred TP appeared to be driven by larger, climatic factors. While laboratory tests involving this product showed sharp reductions in water column TP, management strategies require detailed information on pre-application environmental conditions and variations in order to accurately assess the effectiveness of new technologies for lake management