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  • GEOPHYSICS  (4,821)
  • Life and Medical Sciences  (2,151)
  • 1
    Electronic Resource
    Electronic Resource
    Microscopy in solid state science (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 24 (1993), S. 299-315 
    Details
    ISSN: 1059-910X
    Keywords: STEM ; PEELS ; HAADFI ; Nanolithography ; Super-resolution ; STM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The Microstructural Physics group at the Cavendish Laboratory is actively involved in a considerable number of research projects which cover a broad range of materials science. In this paper, we describe briefly several such projects, with particular emphasis given to the application of parallel-detection electron energy loss spectroscopy (PEELS) on a scanning transmission electron microscope (STEM) to the analysis of materials such as stainless steels, catalysts, and high temperature superconductors. In addition, we describe a number of related projects that are currently being carried out in the group, particularly those which utilise and develop novel STEM imaging and analytical techniques. © 1993 Wiley-Liss, Inc.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070240404
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  • 2
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    Age of the Mulcahy Lake intrusion, northwest Ontario, and implications for the evolution of greenstone-granite terrains (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: An investigation of zircon data from the Mulcahy Lake gabbro, a 63 sq km layered mafic intrusion in the Wabigoon subprovince of Ontario, which show that the gabbro crystallized at 2733.2 +1.0, -0.9 Ma, is considered. It is shown that the gabbro intrudes tholeiites of the Crow Lake-Savant Lake greenstone belt. Whole rock samples and mineral separates from the Mulcahy Lake intrusion are dated by Rb-Sr, Sm-Nd, and Ar-30-Ar-40 techniques. Disturbances in the system are revealed by the Rb-Sr data and an initial Sr ratio of 0.7007 for an age of 2733 Ma is indicated by samples with low Rb/Sr ratios. The age determined for the Sm-Nd data is 2744 + or 55 Ma with an epsilon Nd value of +2.6 + or - 1.2 which indicates a source region depleted in a light rare earth element. Primary hornblende is analyzed for Ar-40/Ar-39 and an age of 2703 + or - 20 is obtained. Some implications for the development of greenstone-granite belts are discussed.
    Keywords: GEOPHYSICS
    Type: Earth and Planetary Science Letters (ISSN 0012-821X); 73; 2-3,
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Landau damping of auroral hiss (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Auroral hiss is observed to propagate over distances comparable to an Earth radius from its source in the auroral oval. The role of Landau damping is investigated for upward propagating auroral hiss. By using a ray tracing code and a simplified model of the distribution function, the effect of Landau damping is calculated for auroral hiss propagation through the environment around the auroral oval. Landau damping is found to be the likely mechanism for explaining some of the one-sided auroral hiss funnels observed by Dynamics Explorer 1. It is also found that Landau damping puts a lower limit on the wavelength of auroral hiss. Poleward of the auroral oval, Landau damping is found in a typical case to limit omega/k(sub parallel) to values of 3.4 x 10(exp 4) km/s or greater, corresponding to resonance energies of 3.2 keV or greater and wavelengths of 2 km or greater. For equatorward propagation, omega/k(sub parallel) is limited to values greater than 6.8 x 10(exp 4) km/s, corresponding to resonance energies greater than 13 keV and wavelengths greater than 3 km. Independent estimates based on measured ratios of the magnetic to electric field intensity also show that omega/k(sub parallel) corresponds to resonance energies greater than 1 keV and wavelengths greater than 1 km. These results lead to the difficulty that upgoing electron beams sufficiently energetic to directly generate auroral hiss of the inferred wavelength are not usually observed. A partial transmission mechanism utilizing density discontinuities oblique to the magnetic field is proposed for converting auroral hiss to wavelengths long enough to avoid damping of the wave over long distances. Numerous reflections of the wave in an upwardly flared density cavity could convert waves to significantly increased wavelengths and resonance velocities.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A2; p. 2471-2488
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
    Electronic Resource
    Electronic Resource
    Comparative kinetics of short and long sperm in sperm dimorphic Drosophila species (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 269-274 
    Details
    ISSN: 0886-1544
    Keywords: minor and major waves ; beat frequeney ; wave propagation velocity ; coiling diameter ; storage effect ; differential behaviour ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: All species of the Drosophila obscura group exhibit within-ejaculate sperm length dimorphism. The present work is a contribution to the understanding of sperm competition through a comparative study of sperm kinetic parameters in four of these species. Videomicrographic observations at 200 frames per second of sperm from males and females, out of the storage organ, prior or after storage were made. Drosophila sperm display both major and minor waves. The former is analysed by measuring coiling diameter (μm) and the latter by recording both beat frequency (s-1) and wave propagation velocity (μm·s-1). Results show that the ‘behaviour’ of short and long spermatozoa noticeably differ: short sperm kinetics remains unaltered after storage while both major and minor waves of long spermatozoa are markedly modified. Thus, evidence is provided here of a sort of “differential activation” which is assumed to result in different survival abilities of short and long sperm within the storage organ of females.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970190405
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  • 5
    Electronic Resource
    Electronic Resource
    Dibutyryl cyclic adenosine monophosphate differentially regulates cell proliferation in low and high alkaline phosphatase SaOS-2 human osteosarcoma cells: Evidence for mediation by the insulin-like growth factor-II system (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 156 (1993), S. 462-468 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the present study, we have sought to determine whether a given signal transduction pathway can have diverse effects on subpopulations of cells of a lineage depending upon the stage of differentiation. To test this hypothesis, we selected the cyclic adenosine monophosphate (cAMP) signal transduction pathway because of its recognized importance in mediating the actions of many hormones, e.g., parathyroid hormone which acts on the bone-forming cells, the osteoblasts. Subpopulations of human osteosarcoma SaOS-2 cells with low (LSaOS) and high (HSaOS) alkaline phosphatase (ALP) content were chosen as model systems for preosteoblasts (pre-OB) and osteoblasts (OB), respectively. Dibutyryl cyclic AMP (DBcAMP) treatment of serum free cultures produced a differential effect on the proliferation of LSaOS cells (40 ± 5% of control at 1 mM DBcAMP, P 〈 0.001) compared with HSaOS cells (no statistically significant effect). The finding supports the hypothesis. Next, we sought evidence for mediation, at least in part, by the insulin-like growth factor (IGF)-II regulatory system. We report that the basal expression of IGF-II, IGF binding protein (IGFBP)-3, and IGFBP-4 was higher in LSaOS cells than in HSaOS cells with the opposite true for type I IGF receptor. DBcAMP treatment of LSaOS cells decreased IGF-II and IGFBP-3 but increased IGFBP-4 and type I IGF receptor; no effect was observed for the type II IGF receptors. DBcAMP treatment of HSaOS cells had no detectable effect on IGF-II; IGFBP-3, or type I and type II IGF receptor expression; only IGFBP-4 expression increased with DBcAMP. These observations suggest that the differential regulation of cell proliferation by the cAMP signal transduction pathway may be mediated, at least in part, by the IGF-II regulatory system. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041560305
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  • 6
    Electronic Resource
    Electronic Resource
    Heparin inhibition of autonomous growth implicates amphiregulin as an autocrine growth factor for normal human mammary epithelial cells (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 153 (1992), S. 103-111 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Normal human mammary epithelial cells (HMECs) proliferate in a serum-free defined growth medium in the absence of epidermal growth factor (Li and Shipley, 1991). Amphiregulin (AR) is a heparin-regulated, EGF-like growth factor. Our observation that one strain of HMECs produce AR mRNA (Cook et al., 1991a) stimulated us to determine whether AR expression was a common phenomenon in HMECs and whether AR could act as an autocrin growth factor to support the EGF-independent growth of these cells. In this study, we detected high levels of AR expression in four separate HMEC strains while one immortal mammary cell line (HBL-100) and six mammary tumor-derived cell lines had low to undetectable levels of AR. The EGF-indendent growth of HMECs was blocked by the addition of heparin or a monoclonal anti-RGF receptors antibody to the culture medium, implication AR as an autocrine growth mediator. This hypothesis is further supported by the fact that medium conditioned by HMECs contains secreted AR protein. A mammary tumor-derived cell line, Hs578T, which proliferates in an EGF-independent manner, does not express detectable levels of AR and is not growth inhibited by heparin. Examination of the same cell types for expression of transforming growth factor type-alpha (TGF-α) mRNA revealed coordinate expression of AR and TGF-α in these cells. These data suggest that both AR and TGF-α mRNA are produced in much greater abundance by normal HMECs than in tumor-derived cells in culture, and that AR is an important autostimulatory factor for the growth of normal HMECs. © 1992 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041530114
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  • 7
    Electronic Resource
    Electronic Resource
    Inhibition of the metabolism of ram spermatozoa by derivatives of α-chlorohydrin (1981)
    New York, NY : Wiley-Blackwell
    Gamete Research 4 (1981), S. 203-217 
    Details
    ISSN: 0148-7280
    Keywords: α-chlorohydrin ; antifertility agent ; ram ; sperm metabolism ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effects of the male antifertility agent, α-chlorohydrin, six of its derivatives, and glycidol were studied on the metabolism of washed ram spermatozoa in vitro with fructose as substrate. The α-chlorohydrin derivatives were the amino, the phosphorylated, and four glycol-bridge (ketal) compounds. All compounds except glycidol, in a concentration between 0.1 and 100 mM, reduced the aerobic glycolsis and/or oxidation of fructose. However, there was not a high correlation between the ability of these compounds to inhibit the metabolism of ram spermatozoa in vitro and their antifertility activity when administered to male rats. Other factors are clearly involved in their antifertility activity, eg, the concentration of the compounds in the epididymis and their conversion of either more or less spermicidal compounds in the body.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120040305
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  • 8
    Electronic Resource
    Electronic Resource
    A simple model for calculating residential 60-Hz magnetic fields (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 11 (1990), S. 283-296 
    Details
    ISSN: 0197-8462
    Keywords: grounding currents ; ELF ; exposure assessment ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A model is presented that permits the calculation of densities of 60-Hz magnetic fields throughout a residence from only a few measurements. We assume that residential magnetic fields are produced by sources external to the house and by the residential grounding circuit. The field from external sources is measured with a single probe. The field produced by the grounding circuit is calculated from the current flowing in the circuit and its geometry. The two fields are combined to give a prediction of the total field at any point in the house. A data-acquisition system was built to record the magnitude and phase of the grounding current and the field from external sources. The model's predictions were compared with measurements of the total magnetic field at a single location in 23 houses; a correlation coefficient of .87 was obtained, indicating that the model has good predictive capability. A more detailed study that was carried out in one house permitted comparisons of measurements with the model's predictions at locations throughout the house. Again, quite reasonable agreement was found. We also investigated the temporal variability of field readings in this house. Daily magnetic field averages were found to be considerably more stable than hourly averages. Finally, we demonstrate the use of the model in creating a profile of the magnetic fields in a home.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250110405
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  • 9
    Electronic Resource
    Electronic Resource
    Plant tubulin genes: Structure and differential expression during development (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 8 (1987), S. 435-460 
    Details
    ISSN: 0192-253X
    Keywords: tubulin genes ; microtubules ; Arabidopsis thaliana ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Microtubules are important components of the cytoskeleton of plant cells and play key roles in plant growth and morphogenesis. Recent molecular studies have begun to elucidate the structure and expression of plant genes coding for the major components of microtubules, α- and β-tubulin. Tubulin amino acid sequences deduced from the DNA sequences of eight higher plant tubulin genes are 79-87% homologous with constitutively expressed mammalian tubulins. The genome of the model plant system Arabidopsis thaliana contains four dispersed α-tubulin sequences and at least seven β-tubulin sequences, only two of which appear to be linked. Of the five A. thaliana genes whose expression has been analyzed, the transcripts of one α-tubulin and one β-tubulin gene are constitutively expressed in roots, leaves, and flowers. A second α-tubulin gene is expressed predominately in flowers; the transcripts of the second and third β-tubulin genes are found predominately in leaves or in roots, respectively.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020080511
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  • 10
    Electronic Resource
    Electronic Resource
    Pulsed magnetic field from video display terminals enhances teratogenic effects of cytosine arabinoside in mice (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 16 (1995), S. 70-74 
    Details
    ISSN: 0197-8462
    Keywords: video display terminals ; embryogenesis ; teratology ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Eighty-nine Swiss Webster mice were randomly divided into four groups: a control group, a pulsed magnetic field (PMF) group, a cytosine arabinoside (ara-C, a teratogen) group, and, a combined PMF + ara-C group. Mice in the PMF and PMF + ara-C groups were irradiated with a PMF (a sawtooth waveform with 52 μs rise time, 12 μs decay time, and 15.6 kHz frequency) at a peak magnetic flux density of 40 μT for 4 hours daily on days 6-17 of gestation. The mice in the ara-C and the PMF + ara-C groups were injected intraperitoneally on day 9 of gestation with 10 mg/kg of ara-C. The incidence of resorption and dead fetuses was not affected by PMF but was increased by ara-C injection. The malformation incidence of cleft palate (CP) and/or cleft lip (CL) was significantly higher in all three of the treated groups than in the control group (P 〈 0.05). If, however, statistical analyses had been done on litters rather than on individual fetuses, they would show that the incidence of CP and/or CL in the PMF group is not significantly greater than that in the control group. A significantly higher incidence of CP and/or CL was found in the PMF + ara-C group (49%) than the ara-C alone group (26.1%). These data suggest that PMF might enhance the development of ara-C-induced CP and/or CL. The incidence of minor variations in skeletal development, including reduction of skeletal calcification and loss of skeleton, was not statistically significant in the PMF group. However, it was higher in the two ara-C-treated groups, and there was no significant difference between the ara-C alone group and the ara-C + PMF group. From these results it is concluded that the very weak embryotoxic effects of PMF exposure may be revealed and enhanced in combination with a teratogenic agent. © 1995 Wiley-Liss, Inc.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250160113
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