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Author  |
Alvarez, J.; Fadic, R. |
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Title |
Assembly and disassembly of axonal microtubules of the toad Xenopus laevis under the effect of temperature |
Type |
Journal Article |
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Year |
1992 |
Publication |
The Journal of Experimental Zoology |
Abbreviated Journal |
J Exp Zool |
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Volume |
264 |
Issue |
3 |
Pages |
261-266 |
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Keywords |
Animals; Axons/*physiology; Cytoplasm/metabolism; Kinetics; Microtubules/*physiology; Seasons; *Temperature; Tubulin/metabolism; Xenopus laevis |
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Abstract |
In toads Xenopus laevis living at 11 degrees (winter), the microtubular density of 4-microns myelinated axons of lumbosacral nerves was assessed with the electron microscope. In controls, the density was 11.2 microtubules/microns2. In nerves incubated at 0 degrees, microtubules decreased following a simple exponential curve with a half time of 4.7 min (k = 0.149 min-1); residual microtubules were 4.5%. After rewarming, the full complement of microtubules reappeared within 60 min. In steady state, the microtubular density exhibited a linear relationship with temperature (range: 0-22 degrees; slope 0.94 microtubules/microns 2 per degree; r, 0.96). After heating the nerve by 11 degrees above the physiological temperature, microtubules increased by 83%, whereby the pool of unpolymerized tubulin was at least 2.7 mg/ml of axoplasm. A seasonal variation of the microtubular density was observed which accorded with the environmental temperature. The macroscopic kinetics of microtubule disassembly in the axoplasm is similar to that reported for purified tubulin but that of assembly is slower. Microtubules of peripheral axons of Xenopus are cold-labile and vary during the annual cycle. |
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Call Number |
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Serial |
1174 |
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Author |
Aro, H.M.; Palosaari, U.K. |
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Title |
Parental divorce, adolescence, and transition to young adulthood: a follow-up study |
Type |
Journal Article |
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Year |
1992 |
Publication |
The American Journal of Orthopsychiatry |
Abbreviated Journal |
Am J Orthopsychiatry |
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Volume |
62 |
Issue |
3 |
Pages |
421-429 |
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Keywords |
Achievement; Adaptation, Psychological; Adolescent; *Adolescent Psychology; Adult; Cohort Studies; Depression/psychology; Divorce/*psychology; Female; Follow-Up Studies; Humans; Interpersonal Relations; Male; *Personality Development; Self Concept; Social Adjustment; Somatoform Disorders/psychology |
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Abstract |
In a long-term study of the effects of divorce, children in a Finnish town who had completed questionnaires in school at age 16 were followed up with postal questionnaires at age 22. Depression in young adulthood was found to be slightly more common among children from divorced families. In addition, the life trajectories of children in divorced families revealed more stressful paths and more distress in both adolescence and young adulthood. |
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Call Number |
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Serial |
279 |
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Author |
Bazela, W.; Leciejewicz, J.; Maletka, K.; Szytula, A. |
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Title |
Magnetic structure of TbAgSn and HoAgSn |
Type |
Journal Article |
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Year |
1992 |
Publication |
Journal of Magnetism and Magnetic Materials |
Abbreviated Journal |
Journal of Magnetism and Magnetic Materials |
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Volume |
117 |
Issue |
1-2 |
Pages |
L1-L4 |
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Keywords |
Polycrystalline; Neutron diffraction; Antiferromagnetically |
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Abstract |
Polycrystalline TbAgSn and HoAgSn have been studied by neutron diffraction. The data obtained at 300 K do not discriminate between the possibilities of the crystal structure being described as (i) the space group P63/mmc (CeIn2 type) with Ag and Sn atoms distributed at random or (ii) by P63mc (GaGeLi type) with an ordered distribution of Ag and Sn. Both compounds order antiferromagnetically: TbAgSn below 33 K and HoAgSn below 15 K with magnetic moments at 4 K of 8.5(1) and 8.8(1) K, respectively. The moments are aligned along the hexagonal axis of the magnetic cell with the dimensions: am = ac, b = ac√3, cm = cc, where ac and cc are the parameters of the crystallographic unit cell. |
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Call Number |
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Serial |
1421 |
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Author |
Bloom, N.S. |
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Title |
On the Chemical Form of Mercury in Edible Fish and Marine Invertebrate Tissue |
Type |
Journal Article |
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Year |
1992 |
Publication |
Canadian Journal of Fisheries and Aquatic Sciences |
Abbreviated Journal |
Can. J. Fish. Aquat. Sci. |
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Volume |
49 |
Issue |
5 |
Pages |
1010-1017 |
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Keywords |
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Abstract |
Total mercury, monomethylmercury (CH3Hg), and dimethylmercury ((CH3)2Hg) in edible muscle were examined in 229 samples, representing seven freshwater and eight saltwater fish species and several species of marine invertebrates using ultraclean techniques. Total mercury was determined by hot HNO3/H2SO4/BrClldigestion, SnCl2 reduction, purging onto gold, and analysis by cold vapor atomic fluorescence spectrometry (CVAFS). Methylmercury was determined by KOH/methanol digestion using aqueous phase ethylation, cryogenic gas chromatography, and CVAFS detection. Total mercury and CH3Hg concentrations varied from 0.011 to 2.78 μg∙g−1 (wet weight basis, as Hg) for all samples, while no sample contained detectable (CH3)2Hg (<0.001 μg∙g−1 as Hg). The observed proportion of total mercury (as CH3Hg) ranged from 69 to 132%, with a relative standard deviation for quintuplicate analysis of about 10%; nearly all of this variability can be explained by the analytical variability of total mercury and CH3Hg. Poorly homogenized samples showed greater variability, primarily because total mercury and CH3Hg were measured on separate aliquots, which vary in mercury concentration, not speciation. I conclude that for all species studied, virtually ail (>95%) of the mercury present is as CH3Hg and that past reports of substantially lower CH3Hg fractions may have been biased by analytical and homogeneity variability.
Subject Headings: Mercury; Edible fish; Marine invertebrate tissue |
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Call Number |
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Serial |
2276 |
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Author |
Bluestone, M |
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Title |
Pitfalls of Genetic Testing |
Type |
Journal Article |
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Year |
1992 |
Publication |
Nature Biotechnology |
Abbreviated Journal |
Nat Biotechnol |
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Volume |
10 |
Issue |
11 |
Pages |
1394-1398 |
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Keywords |
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Abstract |
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Call Number |
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Serial |
740 |
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Author |
Canfield, P.C.; Fisk, Z. |
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Title |
Growth of single crystals from metallic fluxes |
Type |
Journal Article |
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Year |
1992 |
Publication |
Philosophical Magazine B |
Abbreviated Journal |
Philosophical Magazine B |
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Volume |
65 |
Issue |
6 |
Pages |
1117-1123 |
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Keywords |
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Abstract |
Our experience with the growth of a wide variety of intermetallic compounds from molten fluxes is reviewed. Common problems associated with this method of sample growth are discussed, as are problems and advantages of particular fluxes.
Subject Headings: Intermetallic compounds; Molten fluxes; Metallic fluxes |
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Call Number |
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Serial |
2215 |
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Author |
Cohen, M.L. |
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Title |
Epidemiology of drug resistance: implications for a post-antimicrobial era |
Type |
Journal Article |
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Year |
1992 |
Publication |
Science (New York, N.Y.) |
Abbreviated Journal |
Science |
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Volume |
257 |
Issue |
5073 |
Pages |
1050-1055 |
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Keywords |
Bacterial Infections/*drug therapy/epidemiology/prevention & control/transmission; Cross Infection; *Drug Resistance, Microbial; Humans; Risk Factors |
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Abstract |
In the last several years, the frequency and spectrum of antimicrobial-resistant infections have increased in both the hospital and the community. Certain infections that are essentially untreatable have begun to occur as epidemics both in the developing world and in institutional settings in the United States. The increasing frequency of drug resistance has been attributed to combinations of microbial characteristics, selective pressures of antimicrobial use, and societal and technologic changes that enhance the transmission of drug-resistant organisms. Antimicrobial resistance is resulting in increased morbidity, mortality, and health-care costs. Prevention and control of these infections will require new antimicrobial agents, prudent use of existing agents, new vaccines, and enhanced public health efforts to reduce transmission. |
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Call Number |
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Serial |
1129 |
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Author |
Dresser, T.H.; Rivera, E.R.; Hoffmann, F.J.; Finch, R.A. |
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Title |
Teratogenic assessment of four solvents using the frog embryo teratogenesis assay--xenopus (FETAX) |
Type |
Journal Article |
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Year |
1992 |
Publication |
Journal of Applied Toxicology |
Abbreviated Journal |
J. Appl. Toxicol. |
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Volume |
12 |
Issue |
1 |
Pages |
49-56 |
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Keywords |
Xenopus; FETAX; teratogenicity; solvents; ethanol; dimethyl sulfoxide; formamide; glycerol formal |
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Abstract |
The Frog Embryo Teratogenesis Assay—Xenopus (FETAX) was used to assess the teratogenic potential of four solvents. Embryos of the South African clawed frog, Xenopus laevis, were exposed for 96 h to ethanol, dimethyl sulfoxide (DMSO), formamide or glycerol formal. Exposure groups were maintained using a static renewal system in which the exposure media were changed at 24-h intervals. Survival was monitored at 24-h intervals. Length, as an indicator of growth effects, and developmental malformations were determined at the end of the assay (96 h). Using this information, the 96-h LC50, the 96-h EC50 (Malformation), and the no observable effect levels (NOELs) for mortality, malformation and length were determined for each solvent. The teratogenic index [TI = 96-h LC50/96-h EC50 (Malformation)] also was calculated for each of the solvents. DMSO apeared to be the least toxic or teratogenic solvent examined, with a pooled LC50 of 1.92%, a pooled EC50 (Malformation) of 1.57% and TI values of 1.20 and 1.24 in replicate trials. Formamide appeared to be the most toxic solvent, with a pooled LC50 of 1.04%. Data trends suggested that ethanol was the most teratogenic solvent tested, with a pooled EC50 (Malformation) of 1.04% and TI values of 1.42 and 1.50. The results obtained in the present work for ethanol and DMSO were compared to previously published FETAX results for these two solvents. The present results are in close agreement with these results from other laboratories, thus providing further evidence supporting the interlaboratory reproducibility of FETAX results. |
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Call Number |
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Serial |
1473 |
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Author |
Fletterick, R.J. |
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Title |
Introduction to protein structure, by Carl Branden and John Tooze. New York: Garland Publishing Company, 302 pages, $27.95 (paper), 1991 |
Type |
Journal Article |
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Year |
1992 |
Publication |
Proteins: Structure, Function, and Genetics |
Abbreviated Journal |
Proteins |
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Volume |
12 |
Issue |
2 |
Pages |
200-200 |
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Keywords |
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Abstract |
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Call Number |
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Serial |
829 |
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Author |
Ford, J. |
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Title |
The Fermi-Pasta-Ulam problem: Paradox turns discovery |
Type |
Journal Article |
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Year |
1992 |
Publication |
Physics Reports |
Abbreviated Journal |
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Volume |
213 |
Issue |
5 |
Pages |
271-310 |
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Keywords |
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Abstract |
This pedagogical review is written as a personal retrospective which seeks to place the celebrated Fermi, Pasta, and Ulam paradox into historical perspective. After stating the Fermi-Pasta-Ulam results, we treat the questions it raises as a pedagogical “skeleton” upon which to drape (and motivate) the evolving story of nonlinear dynamics/chaos. This review is thus but another retelling of that story by one intimately involved in its unfolding. This is done without apology for two reasons. First, if my colleagues have taught me anything, it is that an audience of experts will seldom pay greater attention than when, with some modicum of grace and polish, they are told things they know perfectly well already. Second, if generations of students have taught me anything, it is that few things fascinate them more than a scientific mystery-- and the Fermi-Pasta-Ulam paradox is a cracker-jack mystery. And so readers, especially graduate students curious about nonlinear dynamics/chaos, are now invited to sit back, loosen their belts (and minds), and prepare for fact that sometimes reads like fantasy.
Subject Headings: Fermi-Pasta-Ulam problem; Discovery; Paradox
Keywords: The Fermi-Pasta-Ulam problem: Paradox turns discovery |
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Call Number |
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Serial |
2555 |
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