Filiations between the Electronic Spectra of C60 and Its Adduct Derivatives: A Rationalization

Considerable similarities are observed between the absorption spectra in the 200–800-nm region of C₆₀ and its n-adduct derivatives (n = 1 − 6), in spite of the fact that two π-electrons are lost for each adduct. The persistence in the adduct derivatives of the main energy and transition strength characteristics of the allowed and forbidden electronic transitions of C₆₀ is rationalized with a relatively simple model. The filial relation between these spectra is discussed on three levels of increasing physical refinement: (i) the electronic states and transitions resulting from a free-electron, spherical shell model of C₆₀; (ii) the effects of an icosahedral potential on such a model; and (iii) the effects of π-electron loss and symmetry lowering due to the addends. The results show that similar, and related, orbital transitions are involved in the absorption spectra in the 200–800-nm region of C₆₀ and its adduct derivatives, albeit mildly affected by changes in molecular symmetry and in the size of the π-conjugation region.     

Stratified newtonian flow calculations by the boundary element method

A boundary integral equation formulation is used to model the stratified flow of two Newtonian viscous liquids, in which the geometrical detail of the interface between the layers is not known in advance. The technique is tested by comparing predictions with the results of previous finite element solutions, and found to perform well. Finally, the method is used to examine the two-layer jet theory of Tanner (1980) as a means of simplifying the modelling of complex extrudate swell problems.     

Influence of dietary protein on reproductive performance of dairy cows

From 10 +/- 3.5 d after parturition to 149 +/- 3.5 d of lactation, 146 cows (109 Holstein and 37 Ayrshires) were fed either a 15 or 20% crude protein diet of 45% sorghum silage and 55% concentrate. Milk production was enhanced by the 20% protein diet, but percentage of milk fat and protein were unchanged. Average daily intake of DM was unaffected by diet. Actual decreases in body weight and condition were small, although cows on 15% protein lost more condition. Concentration of plasma urea nitrogen increased rapidly during the first 4 wk of the experiment with cows on the 20% protein diet maintaining a 10 mg/dl advantage after the 4th wk on experiment. Diet did not affect the postpartum interval to first normal corpus luteum and standing estrus. Cows were inseminated artificially between 55 and 145 d post-calving with one freeze batch of semen from one bull of each appropriate breed mainly by one inseminator. Overall, days open, services per conception, and percentage cows pregnant on experiment were 80, 1.40, and 85, respectively. Concentration of protein in the diet did not affect these reproductive traits. There was no conflict between the amount of dietary protein provided for lactation and reproduction in this experiment.     

Effects of second language study of phonemic discrimination and auditory event-related potentials in adults

This study was designed to investigate the effects of acquisition of a second language on auditory even-related brain potentials and discrimination of foreign language phonemes by 36 women (ages 18 to 47 years), and 25 men (ages 18 to 36 years) and of varying linguistic background, in response to synthetic versions of Japanese phonemes. Subjects were subsequently tested on discrimination between spoken Japanese phonemes. Analysis indicated that the men and women differed in phonological processing and in the way acquisition of the second language affected phonological processing.     

INVESTIGATION OF DOMINANT FREQUENCIES IN TRANSITION REYNOLDS NUMBER RANGE OF FLOW AROUND A CIRCULAR CYLINDER PARTⅡ: THEORETICAL DETERMINATION OF THE RELATIONSHIP BETWEEN VORTEX SHEDDING AND TRANSITION FREQUENCIES AT DIFFERENT REYNOLDS NUMBERS

An attempt has been made to explore whether the power relation can be obtained from theoretical considerations. The classical laminar and turbulent boundary layer concepts have been employed to determine appropriate values of the scaling lengths associated with vortex shedding and shear layer frequencies to predict the power law relationship with Reynolds number. The predicted results are in good agreement with experimental results. The findings will provide a greater insight into the overall phenomenon involved.     

Long term trends in the evolution of H(3) HA1 human influenza type A

We have studied the HA1 domain of 254 human influenza A(H3N2) virus genes for clues that might help identify characteristics of hemagglutinins (HAs) of circulating strains that are predictive of that strain's epidemic potential. Our preliminary findings include the following. (i) The most parsimonious tree found requires 1,260 substitutions of which 712 are silent and 548 are replacement substitutions. (ii) The HA1 portion of the HA gene is evolving at a rate of 5.7 nucleotide substitutions/year or 5.7 x 10(-3) substitutions/site per year. (iii) The replacement substitutions are distributed randomly across the three positions of the codon when allowance is made for the number of ways each codon can change the encoded amino acid. (iv) The replacement substitutions are not distributed randomly over the branches of the tree, there being 2.2 times more changes per tip branch than for non-tip branches. This result is independent of how the virus was amplified (egg grown or kidney cell grown) prior to sequencing or if sequencing was carried out directly on the original clinical specimen by PCR. (v) These excess changes on the tip branches are probably the result of a bias in the choice of strains to sequence and the detection of deleterious mutations that had not yet been removed by negative selection. (vi) There are six hypervariable codons accumulating replacement substitutions at an average rate that is 7.2 times that of the other varied codons. (vii) The number of variable codons in the trunk branches (the winners of the competitive race against the immune system) is 47 +/- 5, significantly fewer than in the twigs (90 +/- 7), which in turn is significantly fewer variable codons than in tip branches (175 +/- 8). (viii) A minimum of one of every 12 branches has nodes at opposite ends representing viruses that reside on different continents. This is, however, no more than would be expected if one were to randomly reassign the continent of origin of the isolates. (ix) Of 99 codons with at least four mutations, 31 have ratios of non-silent to silent changes with probabilities less than 0.05 of occurring by chance, and 14 of those have probabilities <0.005. These observations strongly support positive Darwinian selection. We suggest that the small number of variable positions along the successful trunk lineage, together with knowledge of the codons that have shown positive selection, may provide clues that permit an improved prediction of which strains will cause epidemics and therefore should be used for vaccine production.     

Hard X-Ray Images Created by a Series of Harmonically Related Modulation Collinators

A series of images of hard (30 - 300keV) X-ray sources have been created by use of a multi-pitch rotating modulation collimator (RMC) and a striped NaI(Tl)/CsI(Tl) scintillator detector arrangement. The performance of the system with respect to a series of point and extended objects has been analysed. The implications with respect to space instrumentation are discussed.     

Application of a hybrid computational fluid dynamics and physiologically based inhalation model for interspecies dosimetry extrapolation of acidic vapors in the upper airways

This study provides a scientific basis for interspecies extrapolation of nasal olfactory irritants from rodents to humans. By using a series of short-term in vivo studies, in vitro studies with nasal explants, and computer modeling, regional nasal tissue dose estimates were made and comparisons of tissue doses between species were conducted. To make these comparisons, this study assumes that human and rodent olfactory epithelium have similar susceptibility to the cytotoxic effects of organic acids based on similar histological structure and common mode of action considerations. Interspecies differences in susceptibility to the toxic effects of acidic vapors are therefore assumed to be driven primarily by differences in nasal tissue concentrations that result from regional differences in nasal air flow patterns relative to the species-specific distribution of olfactory epithelium in the nasal cavity. The acute, subchronic, and in vitro studies have demonstrated that the nasal olfactory epithelium is the most sensitive tissue to the effects of inhalation exposure to organic acids and that the sustentacular cells are the most sensitive cell type of this epithelium. A hybrid computational fluid dynamics (CFD) and physiologically based pharmacokinetic (PBPK) dosimetry model was constructed to estimate the regional tissue dose of organic acids in the rodent and human nasal cavity. The CFD-PBPK model simulations indicate that the olfactory epithelium of the human nasal cavity is exposed to two- to threefold lower tissue concentrations of a representative inhaled organic acid vapor, acrylic acid, than the olfactory epithelium of the rodent nasal cavity when the exposure conditions are the same. The magnitude of this difference varies somewhat with the specific exposure scenario that is simulated. The increased olfactory tissue dose in rats relative to humans may be attributed to the large rodent olfactory surface area (greater than 50% of the nasal cavity) and its highly susceptible location (particularly, a projection of olfactory epithelium extending anteriorly in the dorsal meatus region). In contrast, human olfactory epithelium occupies a much smaller surface area (less than 5% of the nasal cavity), and it is in a much less accessible dorsal posterior location. In addition, CFD simulations indicate that human olfactory epithelium is poorly ventilated relative to rodent olfactory epithelium. These studies suggest that the human olfactory epithelium is protected from irritating acidic vapors significantly better than rat olfactory epithelium due to substantive differences in nasal anatomy and nasal air flow. Furthermore, the general structure of the hybrid CFD-PBPK model used for this study appears to be useful for target tissue dosimetry and interspecies dose comparisons for a wide range of inhaled vapors.     

Distal 10q trisomy syndrome with unusual cardiac and pulmonary abnormalities

AIM: To evaluate the use of local transdermic anesthetics in fine needle aspiration biopsy (FNAB) in breast lesions. METHODS: Prospective randomized study of 119 patients having breast lesions, all being indicated for FNAB. The patients were divided into three groups: 40 patients entered in the active group (lidocaine + prilocaine); 40 patients underwent the placebo group (aqueous extract of Triticum vulgaris); and a control group of 39 women in whom FNAB was performed without the administration of any substance. Both the anesthetic and placebo were administered an hour before FNAB. Pain was quantified through a visual analogic scale of pain. The type of pain was also classified in terms of occurrence: only during the puncture, only during the movements and both. RESULTS: The visual linear analogic scale of pain showed an average of 3.3 in the active group, 3.5 in the placebo and 4.0 in the control group (NS). Analysis of the type of pain which was referred by the patient showed that 15% of the patients in the active group, 12.5% of those in the placebo group and 5.1% in the control group did not refer to any sensation of pain. Pain, when felt, was similar in all three groups (p < 0.4). CONCLUSIONS: Both the quantification and the type of pain referred to were similar in all three groups. However, there was a tendency of the patient to refer to less pain when the active substance or the placebo were used, when results were compared to the control group.