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The aerodynamic drag of three different time-trial cycling helmets was analyzed numerically for two different cyclist head positions. Computational Fluid Dynamics (CFD) methods were used to investigate the detailed airflow patterns around the cyclist for a constant velocity of 15 m/s without wind. The CFD simulations have focused on the aerodynamic drag effects in terms of wall shear stress maps and pressure coefficient distributions on the cyclist/helmet system. For a given head position, the helmet shape, by itself, obtained a weak effect on a cyclist's aerodynamic performance (<1.5%). However, by varying head position, a cyclist significantly influences aerodynamic performance; the maximum difference between both positions being about 6.4%. CFD results have also shown that both helmet shape and head position significantly influence drag forces, pressure and wall shear stress distributions on the whole cyclist's body due to the change in the near-wake behavior and in location of corresponding separation and attachment areas around the cyclist.

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The purpose of this study is to develop a numerical methodology based on real data from wind tunnel experiments to investigate the effect of the ski jumper's posture and speed on aerodynamic forces in a wide range of angles of attack. To improve our knowledge of the aerodynamic behavior of the ski jumper and his equipment during the early flight phase of the ski jump, we applied CFD methodology to evaluate the influence of angle of attack (α=14°, 21.5°, 29°, 36.5° and 44°) and speed (u=23, 26 and 29m/s) on aerodynamic forces in the situation of stable attitude of the ski jumper's body and skis. The standard k-ω turbulence model was used to investigate both the influence of the ski jumper's posture and speed on aerodynamic performance during the early flight phase. Numerical results show that the ski jumper's speed has very little impact on the lift and drag coefficients. Conversely, the lift and drag forces acting on the ski jumper's body during the early flight phase of the jump are strongly influenced by the variations of the angle of attack. The present results suggest that the greater the ski jumper's angle of inclination, with respect to the relative flow, the greater the pressure difference between the lower and upper parts of the skier. Further studies will focus on the dependency of the parameters with both the angle of attack α and the body-ski angle ß as control variables. It will be possible to test and optimize different ski jumping styles in different ski jumping hills and investigate different environmental conditions such as temperature, altitude or crosswinds.

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The effect of tetanus toxin on neuropeptide hormone release from isolated nerve endings of the neural lobe of rat pituitaries (neurosecretosomes) was measured in a perfusion system. Tetanus toxin inhibited depolarization-evoked release of oxytocin and vasopressin in a time- and dose-dependent manner. At 1 microgram/ml, tetanus toxin blocked stimulated release by 85%. Tetanus toxin that was preincubated with a neutralizing monoclonal antibody or heated to 100 degrees C had no effect on hormone release. The ionophores A23187 and ionomycin were potent stimulators of hormone release in control nerve endings, but were not able to overcome the effect of tetanus toxin in intoxicated nerve endings. 8-Bromo-cyclic GMP, which has been reported to reverse the action of tetanus toxin in PC12 cells, had no effect on the action of tetanus toxin in neurosecretosomes. Neurosecretosomes are the first system in which tetanus toxin has been shown to block release from peptidergic nerve terminals. They appear to be a valuable in vitro system for studying the biochemical mechanism of tetanus toxin action.

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The effect of neonatal deafferentation of the rat superior cervical ganglion (SCG) on the expression of two synaptic vesicle proteins was studied to assess the role of transsynaptic influences in the regulation of these neural antigens in the SCG. The two proteins studied were a 65 kilodalton integral membrane protein of synaptic vesicles (SV), and synapsin-1 (S-1), a synaptic vesicle phosphoprotein. Antigen levels were quantified by radioimmunoassay using antibodies directed against the proteins. Distribution of SV in control, deafferented and reinnervated ganglia from 30-day-old rats was visualized by immunohistochemical labeling. Levels of both antigens were reduced following deafferentation of the SCG on postnatal days 1-3. The reduction in S-1 levels at 30 days was less than that observed for SV. The amount of S-1 remaining in deafferented ganglia was consistent with estimates of the postsynaptic pool in the SCG reported previously. SV levels, in contrast, were reduced to 24% of control levels, suggesting that SV synthesis in principal ganglionic neurons might be affected. The time course of postnatal development of S-1 in the SCG differed from previous studies of SV expression, with significant increases occurring after the second week after birth. The differences in response to deafferentation may reflect functional differences of the two vesicle-associated proteins. These studies demonstrate that transsynaptic regulation of antigens other than those directly associated with neurotransmitters occurs in the SCG.

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Several short-chain alkynoic and aikenoic acids and esters were screened for inhibition of gas production by Clostridium botulinum in cans of comminuted, nitrite-free, temperature-abused bacon. The most active compounds were propiolic (2-propynoic) acid, methyl and ethyl propiolate, 2-propenoic acid, methyl and ethyl propenoate, and mono- and dimethyl and ethyl fumarate. Maleic acid, methylmaleic acid, ethyl maleate, 2-methyl propenoic acid, trans-2-methyl crotonic acid, 3-methyl-2-butenoic acid, 3-methylallyl alcohol, vinyl crotonate, methylmalonic acid, dimethyl glutarate, 2,4-hexadien-1-ol, cis-3-hexenoic acid, 4-pentenoic acid, trans-2-pentenoic acid and ethylidene acetic acid were less active. A more comprehensive study on the inhibition of toxin formation by C. botulinum in comminuted nitrite-free bacon was done by comparing equimolar quantities of some of these compounds with NaNO2 at 120 µg/g and sorbic acid at 9 and 18 mM (0.10 and 0.20%). These studies showed that propiolic acid was more effective than either nitrite or sorbic acid. Compounds in this study less active than nitrite or sorbic acid were 3-methylallyl alcohol, 2,4-hexadien-1-ol, dimethyl glutarate and methylmaleic acid.

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The effect of neonatal deafferentation on the expression of a neuronal cell surface heparan sulfate proteoglycan (HeS-PG) was investigated in the developing rat superior cervical ganglion. Two monoclonal antibodies, one directed against the core protein of HeS-PG, and one to a determinant associated with a heparan sulfate side-chain, were used to monitor postnatal increases of HeS-PG by radioimmunoassay. Following neonatal deafferentation by section of the cervical sympathetic trunk, total protein per ganglion was slightly reduced at survival times of 7, 14, and 30 days. Expression of the core protein determinant on HeS-PG was not altered in deafferented ganglia. In contrast, levels of side-chain determinant were significantly reduced at 14 and 30 days. These results suggest that processing of HeS-PG side-chains by principal ganglionic neurons is partially regulated by transsynaptic influences during development. Transsynaptic regulation of neuronal development may be a more general process than was believed previously, with effects not limited to molecules associated with synaptic development.

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The effectiveness of combinations of sorbic acid and other acids (hydrochloric, phosphoric, acetic, citric, lactic and succinic) on Clostridium botulinum inhibition in comminuted ham and nitrite-free bacon was studied. These acids, when added to ham to give similar pH's, did not significantly inhibit the organism, but when acetic or citric acid was added with sorbic acid, inhibition was greater than with sorbic acid alone. The acids were less effective in inhibiting C. botulinum when added to sorbic acid-containing bacon. A study of the effectiveness of three levels of potassium sorbate (0.10, 0.26 or 0.52%) or sorbic acid (0.08, 0.20 or 0.40%) and two levels of phosphoric acid (0.04 or 0.08%) in comminuted ham showed that the highest levels of sorbate or sorbic acid were sufficient to inhibit toxin production when incubated at 30°C for 180 d. The same degree of C. botulinum inhibition was afforded by 0.26% sorbate with 0.08% H3PO4 or by 0.20% sorbic acid with 0.04% H3PO4. These differences were probably due to the higher pH obtained with sorbate.

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Saturated aliphatic acids (C1 to C20) and n-alkyl formate, acetate, propionate and butyrate esters (C1 to C20) were evaluated to determine the minimum inhibitory concentrations (MIC) necessary to inhibit the growth of Clostridium botulinum 62A in a bacteriological medium. The C1 to C7 and C16 to C20 acids and esters were relatively inactive (MIC > 200 µg/ml). The C8 to C15 acids exhibited some antibotulinal acitivity (MIC = 100 µg/ml), whereas C8 to C15 esters were substantially more inhibitory. The n-alkyl formates, acetates and propionates having C13 to C14 groups gave the highest inhibition, with MIC's of 3.1, 6.3 and 6.3 µg/ml, respectively. The maximum inhibition for the butyrates (MIC = 12.4 µg/ml) was associated with C11 to C12 alkyl groups. A mathematical relationship between activity and alkyl group chain length was derived.

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A procedure was developed and used to obtain the optimal shape of corrected aspheric geodesic lenses for F-numbers ranging from 3 to 15. This optimization procedure allows the (constant) refractive index, lens radius, and focal length to be used as independent design parameters. Results of the increase in size of the first diffraction spot and shift in the focal plane caused by perturbations in a lens's shape have been included for several lenses with F-numbers between 3 and 10.

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