A physiologically based approach to the study of bisphenol A and other estrogenic chemicals on the size of reproductive organs, daily sperm production, and behavior

Two chemicals previously shown to have estrogenic activity, bisphenol A and octylphenol, were examined for their effects on accessory reproductive organs and daily sperm production in male offspring of mice fed these chemicals during pregnancy. These chemicals are used in the manufacture of plastics and other products, and have been detected in food and water consumed by animals and people. From gestation day 11-17 female mice were fed an average concentration (dissolved in oil) of bisphenol A or octylphenol of 2 ng/g body weight (2 ppb) and 20 ng/g (20 ppb). The 2 ppb dose of bisphenol A is lower than the amount reported to be swallowed during the first hour after application of a plastic dental sealant (up to 931 micrograms; 13.3 ppb in a 70 kg adult). We found that the 2 ng/g dose of bisphenol A permanently increased the size of the preputial glands, but reduced the size of the epididymides; these organs develop from different embryonic tissues. At 20 ng/g, bisphenol A significantly decreased efficiency of sperm production (daily sperm production per g testis) by 20% relative to control males. The only significant effect of octylphenol was a reduction in daily sperm production and efficiency of sperm production at the 2 ng/g dose. A new approach to studying physiologically relevant doses of environmental endocrine disruptors is discussed, particularly with regard to the development of the reproductive organs, the brain, and behavior.     

Heat transfer between particle beds and submerged surfaces

Theoretical modelling of heat transfer to particle beds comprises two sequential steps: transfer from the heating surface to contacting particles followed by transfer to the interior of the bed. Two different limiting case can be formulated for the second step: unmixed and homogeneously mixed bed. In the case, heat is transferred gradually via a repeated sequence of heat transfer in the gap between adjacent particles and conduction in the particulate material. In the second case, heat is transferred to the interior of the bed by mixing of particles which have previously attained the temperature of the heating surface. On the other hand, the mixing motion maintains a homogeneous lower temperature throughout the bed. Theory predicts a significant and easily measurable difference in the behaviour of heat transfer coefficients for the two regimes at long contact times t: unmixed beds ∝ $$ \sqrt t $$ and homogeneously mixed beds ∝ 1/t. For short times t, both regimes show the same behaviour, namely of t. From a theoretical standpoint, it makes sense to differentiate further between the behaviour patterns of unmixed beds: at long times t, instantaneous heat transfer coefficients are independent of heat transfer form the heating surface to adjacent particles. Comparison with experimental result from literature shows that the derived models, which are consistent, are suitable for describing the heat transfer from submerged surfaces to unmixed and mixed beds of particles.     

Analysis of nonorthogonal designs: The 2k factorial experiment.

Asimple unweighted means ANOVA of a 2k factorial experiment with unequal and disproportionate cell frequencies resulted in the same sums of squares and F tests as the more complex Method 1 analysis recommended by J. E. Overall et al (see record 1975-20136-001). (6 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of the temperature dependence of the fracture stress of sharp notched bending specimens of a structural steel with respect to intermediate transitions

The flow and fracture stresses, σ_y^g and σ_f^g (δ = crack tip displacement), of sharply notched bending specimens of a structural steel U St 37-1 are measured in the temperature range from full scale to small scale yielding. The best adaption of the experimental results for σ_f^g is obtained by a curve which exhibits an intermediate transition, i.e. which follows in a temperature range between an upper, T_tM¹ and a lower, T_tl¹, transition temperature to the curve σ_y^g(T) for the flow stress with a constant δ = δ₁. This transition corresponds to that of the slip to the twin nucleated fracture. Two analyses [3,5] according to the local fracture stress, σ_f^*, concept show that the amount and the temperature dependence of σ_f^* are somewhat different for both methods, but that both exhibit an increase of σ_f^* in the transition range. It is concluded that each transition in the nucleation mode of the fracture is connected with such a transition in the fracture stress. It may, however, become indistinct or even be covered by the scatter of the experimental points.     

Nuclear susceptibility of liquid He3—I

An accurate study of the nuclear molar susceptibility of liquid He ³ has been made. Particularly emphasized was the comparison of in the liquid with that in solid He ³ . The experimental results of this work define a three-dimensional surface T/C versus temperatureT and molar volumeV between 0.35 and 2.2° K and between 26 and 37 cm ³ /mole. HereC is the molar Curie constant of solid He ³ , assumed to beN _A µ ² /k _B T, where is the nuclear magnetic moment and N _A Avogadro's number. The measurements were accomplished using a carefully designed pulsed NMR set, and sample-and-hold circuitry with a digital voltmeter for readout. Most of the measurements were made at fixed temperature relative to a sample of bcc solid He ³ , usually at a density of 22.50 cm ³ /mole. These data were complemented by measurement of versusT at fixed pressure. Except at the highest temperatures, the scatter in the values was about 0.3%, and the results are estimated to be accurate within ±0.5%. At sufficiently high temperatures, the susceptibility is found to tend asymptotically towards Curie's law by comparison with solid He ³ . The deviation from Curie's law, to temperatures near 0.5° K, could be empirically written as (1–T/C)=bT ^d whereb andd are density-dependent parameters. Comparison with theories and previous measurements of the nuclear susceptibility are made. Below 1° K, the present results are about midway between those of Beal and Hatton ⁹ and those of Thomson, Meyer, and Adams. ⁸ Research supported by a grant from the National Science Foundation and from the AROD. The results have been presented as an Abstract inBull. Am. Phys. Soc. 14, 601 (1969), submitted in partial fulfillment for the Ph.D. in physics by J. R. Thompson, May 1969.     

Grid-Computing

Grid-Computing, ein Mitte der 90er-Jahre eingeführter Begriff [1,2], bezeichnet eine Architektur für verteilte Systeme, die auf dem World Wide Web aufbaut und die Web-Vision erweitert. Mit dem Grid-Computing werden die Ressourcen einer Gemeinschaft, einer so genannten virtuellen Organisation, integriert. Die Hoffnung ist, dass hierdurch rechen- und/oder datenintensiven Aufgaben, die eine einzelne Organisation nicht lösen kann, handhabbar werden. Ein Grid bezeichnet eine nach dem Grid-Computing-Ansatz aufgebaute Rechner-, Netzwerk- und Software-Infrastruktur zur Teilung von Ressourcen mit dem Ziel, die Aufgaben einer virtuellen Organisation zu erledigen.