Alterations in the developmental properties of stroma during the development of the urogenital ridge into ductus deferens and uterus in embryonic and neonatal mice

The ability of mesenchyme from the urogenital ridge to participate in the development of male and female urogenital organs was studied by preparing homo- and heterotypic recombinants of epithelium and stroma from ductus deferens and uterus of neonatal mice. The recombinants as well as intact 14-day old embryonic urogenital ridges (URG) were grown for two to eight weeks in adult male and female hosts. The development of ductus deferens and seminal vesicle from female UGR's grafted into male hosts and uterus from male UGR's grafted into female hosts demonstrate that the mesenchyme of embryonic UGR's is capable of participating in the development of either male or female urogenital structures. During normal development of the female urogenital tract, the bisexual morphogenetic potentiality of UGR mesenchyme persists postnatally as demonstrated by the ability of uterine stroma to support normal differentiation of epithelium of ductus deferens in male hosts. Conversely, during the normal development of the male urogenital tract, the morphogenetic potentiality of mesenchyme of the urogenital ridge is restricted as stroma from the ductus deferens appears incapable of participating in uterine morphogenesis in male or female hosts. These differences in the developmental properties of UGR stroma may be attributed to differences in hormonal conditions in male and female fetuses.     

Lack of effect of hypocalcemia on renal phosphate handling

A possible effect of decreased plasma ionized calcium concentration on renal phosphate handling was investigated in dogs with control of parathyroid hormone. Intrarenal artery infusion of either EDTA or sodium citrate decreased ionized calcium concentration 25 per cent in renal vein blood but had no significant effect on fractional phosphate excretion. Similarly, intravenous infusion of chelators had no significant effect on fractional phosphate excretion. It is concluded that acute decreases in ionized calcium have no significant effect on the renal handling of phosphate.     

A study of solvent effects on the phosphorescence properties of flavins

A combination of zero field triplet state techniques are used to study the excited electronic states of a series of flavin and flavin related molecules both in single crystals and glass matrices. Particular attention is given to the effects of solvent interaction on the triplet state properties of the flavin molecules. The total phosphorescence decay rate constants at 1.4 degrees K are reported for the flavin molecules in polar and nonpolar solvents. The rate constants are then correlated to the degree of solvent interaction. Results indicate possible complex formation between the isoalloxazine and adenine groups in FAD. Finally, the results and possible interpretation on the study of a flavoenzyme, L-amino acid oxidase are presented.     

Quantification of Obstructions in Vessels by Nuclear Magnetic Resonance (NMR)

The sequence of radiofrequency and magnetic field gradients used to form an NMR image produces changes in the signals emitted by moving blood when compared to the signals from stationary blood. These changes can be used to measure the open area of vessels. In addition, specific relaxation time signatures of lesions may help in identifying the nature of the obstructions.     

Modeling Strategy for Back-to-Back Three-Level Converters Applied to High-Power Wind Turbines

Three-level converters are becoming a realistic alternative to the conventional converters in high-power wind-energy applications. In this paper, a complete analytical strategy to model a back-to-back three-level converter is described. This tool permits us to adapt the control strategy to the specific application. Moreover, the model of different loads can be incorporated to the overall model. Both control strategy and load models are included in the complete system model. The proposed model pays special attention to the unbalance in the capacitors' voltage of three-level converters, including the dynamics of the capacitors' voltage. In order to validate the model and the control strategy proposed in this paper, a 3-MW three-level back-to-back power converter used as a power conditioning system of a variable speed wind turbine has been simulated. Finally, the described strategy has been implemented in a 50-kVA scalable prototype as well, providing a satisfactory performance     

Emotional arousal, eating patterns, and body image as differential factors associated with varying success in maintaining a weight loss.

Compared 19 female and 3 male overweight Ss who had maintained a weight loss for a 1-yr period by means of questionnaires, interviews, and tests with 30 females and 4 males who had regained the weight they had lost and 28 female and 11 male normal controls. The regainers indicated eating in response to a variety of states of emotional arousal. The maintainers reported that eating was more specific to loneliness and boredom; results from the control group showed that food consumption was primarily in response to hunger. The regainers rated the concept of eating in a more positive and active direction than did the maintainer group. The regainers' greater difficulty in maintaining a weight loss may be related to a large number of emotional states that are discriminative stimuli for food intake. (30 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Free radicals in coal and coal conversions. 9. Statistical correlative models of the effect of process variables on hydroliquefaction products

Previous papers in this series have reported the degree of coal conversion in autoclave and e.s.r. cavity liquefaction experiments and free radical measurements from the e.s.r. liquefaction experiments. Here a correlative model for the liquefaction products is discussed in terms of temperature,solvent reactor type, pressure and other process variables, similar in form to that used for the free-radical concentration measurements in an earlier paper in this series. Solvent-time interactions were found to be the most significant term in modelling the yields. Based on the strong similarity in the functional form of the radical and product yield models, a model of conversion and the various yields as a fraction of radical concentration and other process variables was constructed. Free-radical concentration and its interaction with solvent were found to be very significant.     

Color, iridescence, and thermoregulation in Lepidoptera

This paper examines evidence for the hypothesized connection between solar thermal properties of butterfly and moth (Lepidoptera) wings, iridescence/structural color, and thermoregulation. Specimens of 64 species of Lepidoptera were measured spectrophotometrically, their solar absorptances calculated, and their habitat temperatures determined. No correlation was found between habitat temperature and the solar absorptance of the wings. It was found, however, that the iridescent specimens exhibited, on average, substantially higher solar absorptance than noniridescent ones.     

Multi-level effects of sulphur-iron interactions in freshwater wetlands in The Netherlands

Although sulphur deposition rates in Europe have considerably decreased over the last decades, sulphate concentrations in freshwater wetlands are still high, as a result of drainage, nitrate pollution, and increased sulphur loads in rivers. High sulphur fluxes may cause sulphide toxicity and eutrophication, and strongly interfere with the biogeochemical cycling of iron and phosphorus. In the present study the ecotoxicological interactions between sulphur, phosphate, iron, and trace metals in freshwater wetlands are reviewed.