Effects of different footwear on landing forces from a grand jeté in trained dancers

The Grand Jete movement is a popular leap elevation movement used in ballet, modern, contemporary and jazz dance. The move involves taking off from one foot and landing on the other foot reaching the highest point possible in the air and lifting legs to a split position. Dancers may perform many grand jetes in a single routine. The aim of this study was to investigate whether footwear used by dancers can reduce the vertical impact forces caused by landing from high leaps. The study was approved by the university’s ethics committee and informed consent was given by ten highly-trained dancers (age mean 23.1, s=1.6 years; height 1.64, s=.08 m; mass 57.7, s=5.2 kg). The participants all performed a grand jete in three different footwear conditions: bare feet, jazz shoes and dance trainers with shock absorbing properties. Landing forces were recorded using a Kistler force plate sampling at 1000 Hz. Peak impact force was determined as the maximum vertical force occurring during the first 0.07 s of contact. Statistical analysis consisted of repeated measures ANOVA. Maximumforce during the landing phase decreased from 4.00 BW (s=0.72) in the barefoot condition to 3.95 BW (s=0.69) in the jazz shoes condition and 3.58 BW (s=0.68) in the trainers condition (F2,9=2.5, P=0.108, Z2=0.22, power=0.44).Higher impact peak and loading rate values were found in the barefoot condition compared to the shodconditions, with the trainers showing the lowest values. However, there were no significant differences between the footwear conditions for impact peak force(F2,9=0.50, P¼0.616, Z2=0.05, power=0.12),time-to-peak impact force (F2,9=0.44 , P=0.653, Z2=0.05, power=0.11), or loading rate to the poin of maximum vertical force (F2,9=0.53, P=0.597, Z2=0.06, power=0.12). The results showed lower maximum landing forces, impact peak force and loading rates in the dance trainers compared to the barefoot and jazz shoes conditions. Although the values were not significantly different, the small difference between footwear conditions may prove important with the onset of fatigue during a routine. Dancers should train to develop safe landing techniques when performing barefooted

The Unicellular State as a Point Source in a Quantum Biological System.

A point source is the central and most important point or place for any group of cohering phenomena. Evolutionary development presumes that biological processes are sequentially linked, but neither directed from, nor centralized within, any specific biologic structure or stage. However, such an epigenomic entity exists and its transforming effects can be understood through the obligatory recapitulation of all eukaryotic lifeforms through a zygotic unicellular phase. This requisite biological conjunction can now be properly assessed as the focal point of reconciliation between biology and quantum phenomena, illustrated by deconvoluting complex physiologic traits back to their unicellular origins

A systematic approach to cancer: evolution beyond selection.

Cancer is typically scrutinized as a pathological process characterized by chromosomal aberrations and clonal expansion subject to stochastic Darwinian selection within adaptive cellular ecosystems. Cognition based evolution is suggested as an alternative approach to cancer development and progression in which neoplastic cells of differing karyotypes and cellular lineages are assessed as self-referential agencies with purposive participation within tissue microenvironments. As distinct self-aware entities, neoplastic cells occupy unique participant/observer status within tissue ecologies. In consequence, neoplastic proliferation by clonal lineages is enhanced by the advantaged utilization of ecological resources through flexible re-connection with progenitor evolutionary stages

Guidance, flight mechanics and trajectory optimization. Volume 2 - Observation theory and sensors

Observation theory and sensors applicable to navigation of boost and space vehicle

Nuclear fusion induced by X-rays in a crystal

The nuclei that constitute a crystalline lattice, oscillate relative to each other with a very low energy that is not sufficient to penetrate through the Coulomb barriers separating them. An additional energy, which is needed to tunnel through the barrier and fuse, can be supplied by external electromagnetic waves (X-rays or the synchrotron radiation). Exposing to the X-rays the solid compound LiD (lithium-deuteride) for the duration of 111 hours, we have detected 88 events of the nuclear fusion d+Li6 ---> Be8*. Our theoretical estimate agrees with what we observed. One of possible applications of the phenomenon we found, could be the measurements of the rates of various nuclear reactions (not necessarily fusion) at extremely low energies inaccessible in accelerator experiments.Comment: 27 pages, 12 figures; submitted to Phys. Rev. C on 28 October 201

Oxygen production on Mars and the Moon

Significant progress was made in the area of in-situ oxygen production in the last year. In order to reduce sealing problems due to thermal expansion mismatch in the disk configuration, several all-Zirconia cells were constructed and are being tested. Two of these cells were run successfully for extended periods of time. One was run for over 200 hours and the other for over 800 hours. These extended runs, along with gas sample analysis, showed that the oxygen being produced is definitely from CO2 and not from air leaks or from the disk material. A new tube system is being constructed that is more rugged, portable, durable, and energy efficient. The important operating parameters of this system will be better controlled compared to previous systems. An electrochemical compressor will also be constructed with a similar configuration. The electrochemical compressor will use less energy since the feed stock is already heated in the separation unit. In addition, it does not have moving parts

Ion beam sputter etching and deposition of fluoropolymers

Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanism and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE