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  • 1995-1999  (11)
  • 1880-1889
  • 1999  (11)
  • 1
    Electronic Resource
    Electronic Resource
    TiNx films with metallic behavior at high N/Ti ratios for better solar control windows (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 630-632 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using cathodic arc deposition with 700 eV nitrogen ion assistance, metallic response in TiNx thin films to at least N/Ti=1.3 is found. Metallic behavior is usually limited to N/Ti ratios just above 1.1. Defects are almost exclusively Ti vacancies which further enhances optical changes. The resulting large shift in onset of Drude reflection to longer wavelengths enhances the view, daylighting, and environmental performance of a coated window relative to stoichiometric TiN films on glass. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124463
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  • 2
    Electronic Resource
    Electronic Resource
    Substrate effects on GaN photoconductive detector performance (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 25-27 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaN photoconductive detectors were fabricated on three substrates: sapphire, SiC, and GaN-on-sapphire substrates. The undoped GaN was deposited on each substrate by metalorganic vapor phase epitaxy. The structural properties, as measured by transmission electron microscopy, x-ray diffraction, and atomic force microscopy, of the layers grown on GaN-on-sapphire and SiC were superior to those of the layers grown on sapphire. A corresponding improvement in optical response and sharpness of optical response of the photoconductive detectors was observed with improved material quality. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124265
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  • 3
    Electronic Resource
    Electronic Resource
    The effects of fish on assemblages of amphibians in ponds: a field experiment (1999)
    Oxford, UK : Blackwell Science, Ltd
    Freshwater biology 41 (1999), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Bluegill sunfish (Lepomis macrochirus) dominate fish assemblages of small lakes and ponds throughout the eastern United States and may play a major role in structuring aquatic communities. We examined the impact of adult bluegill on amphibian density by stocking bluegill at a range of densities into partitions of an experimental pond in which amphibians were free to colonize.2. Adult bluegill had a major impact on the amphibian assemblage. By the end of the experiment, gray treefrog (Hyla versicolor) tadpoles were nine times less abundant, and red-spotted newt (Notophthalmus viridescens) adults were three times less abundant in the presence of adult bluegill than in their absence. In contrast, bullfrog (Rana catesbeiana) tadpoles tended to increase in the presence of adult bluegill. Adult bluegill also had a negative effect on the abundance of predaceous aquatic insects.3. There was no indication that interactions among amphibians were significant in determining the above patterns. We suggest that the strong impact of adult bluegill resulted from a combination of direct and indirect effects on amphibian larvae and predaceous aquatic insects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.1999.00445.x
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  • 4
    Electronic Resource
    Electronic Resource
    Ionic currents that contribute to a sexually dimorphic communication signal in weakly electric fish (1999)
    Springer
    Journal of comparative physiology 185 (1999), S. 379-387 
    Details
    ISSN: 1432-1351
    Keywords: Key words Electric fish ; Pacemaker ; Sexual dimorphism ; Ionic currents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Weakly electric fish produce a communication signal, the electric organ discharge, that is species specific, and in many species, sexually dimorphic. Because the neural circuit that controls the electric organ discharge is relatively simple, it is an excellent model in which to study both the biophysical mechanisms underlying a rhythmic behavior and the neuroendocrine control of a sexually dimorphic behavior. By studying the effects of ion channel blockers on neurons in the medullary pacemaker nucleus, I pharmacologically characterized three ionic currents that influence the pacemaker rhythm, and thus electric organ discharge frequency, in the gymnotiform fish, Apteronotus leptorhynchus. These currents included a tetrodotoxin-sensitive sodium current; a potassium current that was sensitive to 4-aminopyridine; and a calcium current that was sensitive to nickel and cadmium, but resistant to specific blockers of L-, N-, P-, and Q-type calcium currents. The pharmacological profiles of the ionic currents in the pacemaker nucleus are similar to those of ionic currents involved in pacemaking in other neuronal oscillators. Because these ionic currents dramatically influence pacemaker firing frequency, which is directly related to electric organ discharge frequency, these ionic currents are likely targets of steroid hormone action in producing sexual dimorphisms in electric organ discharge frequency. Additional studies are needed to determine how these ionic currents interact to generate the electric organ discharge rhythm and to investigate the possibility that sexual dimorphism in the electric organ discharge results from the actions of gonadal steroids on these ionic currents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050398
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  • 5
    Electronic Resource
    Electronic Resource
    Cell cycle of symbiotic dinoflagellates: variation in G1 phase-duration with anemone nutritional status and macronutrient supply in the Aiptasia pulchella–Symbiodinium pulchrorum symbiosis (1999)
    Springer
    Marine biology 134 (1999), S. 405-418 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The metabolite exchange in alga–invertebrate symbioses has been the subject of extensive research. A central question is how the biomass of the algal endosymbionts is maintained within defined limits under a given set of environmental conditions despite their tremendous growth potential. Whether algal growth is actively regulated by the animal cells is still an open question. We experimentally evaluated the effect of inorganic nutrient supply and host-animal nutritional status on the biomass composition, growth and cell-cycle kinetics of the endosymbiotic dinoflagellate Symbiodinium pulchrorum (Trench) in the sea anemone Aiptasia pulchella. Dinoflagellates in anemones starved for 14 d exhibited lower growth rates, chlorophyll content and higher C:N ratios than in anemones fed Artemia sp. (San Francisco brand #65034) nauplii every 2 d, indicating N-limitation of the algae during starvation of the host animal. Manipulation of the dissolved inorganic nutrient supply through ammonium and phosphate additions induced a rapid recovery (half time, t ½∼ 2 d) in the C:N ratio of the dinoflagellate cells to levels characteristic of N-sufficient cells. The mitotic index and population growth rate of the dinoflagellate symbionts subjected to this enrichment did not recover to the levels exhibited in fed associations. Flow cytometric analysis of dinoflagellate cell size and DNA content revealed that the duration of the G1 phase (first peak of DNA content: 70 to 100 relative fluorescence units, rfu) of their cell cycle lengthened dramatically in the symbiotic state, and that the majority of algal biomass increase occurred during this phase. Covariate analysis of dinoflagellate cell size and DNA-content distributions indicated that the symbiotic state is associated with a nutrient-independent constraint on cell progression from G1 through the S phase (intermediate DNA content: 101 to 139 rfu). This analysis suggests that the host-cell environment may set the upper limit on the rate of dinoflagellate cell-cycle progression and thereby coordinate the relative growth rates of the autotrophic and heterotrophic partners in this symbiotic association.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050557
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  • 6
    Electronic Resource
    Electronic Resource
    On `globbicity' of low-resolution protein structures (1999)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 230-237 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Using Harker's [Harker (1953). Acta Cryst. 6, 731–736] idea of spherically averaged polyatomic groups or `globs' as the units of structure suitable for analyzing low-resolution diffraction data from protein crystals, `globbic' scattering factors have been calculated for main-chain peptide units and amino-acid side-chain groups to 3 Å resolution via Debye's [Debye (1915). Ann. Phys. (Leipzig), 46, 809–823] scattering formula. It is shown that the scattering factors are insensitive to intra-globbic conformational variation and can be approximated fairly well by a single-Gaussian formula, i.e. fg(s) = Zg exp(−1.7Zgs2), where s = (sinθ)/λ and Zg is the total electron count for the atoms of the glob. Phase errors due to the globbic approximation and their effect on electron-density maps at 3.5 Å resolution have been assessed via calculations for the crambin structure; this analysis indicates that the globbic scattering factors will be useful in efforts to develop procedures for direct-methods phasing of diffraction data to ∼3.5 Å resolution from protein crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444998008208
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  • 7
    Electronic Resource
    Electronic Resource
    Difference structure-factor normalization for heavy-atom or anomalous-scattering substructure determinations (1999)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 32 (1999), S. 664-670 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Procedures are described for normalizing structure-factor difference magnitudes, |Δ|F||SIR = ||FDer| − |FNat|| ≤ |FHeavy| or |Δ|F||SAS = ||F+h| − |F−h|| ≤ 2|F′′|, to prepare data for probabilistic direct methods phasing to determine heavy-atom or anomalous-scattering substructures in SIR (single-derivative isomorphous replacement) or SAS (single-wavelength anomalous scattering) cases. Applications of the procedures in several recent determinations of multi-selenium substructures in selenomethionyl proteins via SnB direct-methods phasing are briefly summarized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889899003416
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  • 8
    Electronic Resource
    Electronic Resource
    Use of simultaneous IR temperature measurements and DPIV to investigate thermal plumes in a thick layer cooled from above (1999)
    Springer
    Experiments in fluids 27 (1999), S. 70-78 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Simultaneous measurements of surface temperature and the underlying velocity field are presented for a thick horizontal layer evaporatively cooled from above. Previous studies have focused on either the temperature field at the cooled surface or, in a small number of cases, on point velocity measurements in the flow. The current investigation is, to the knowledge of the authors, the first to simultaneously and non-intrusively document both the surface temperature and underlying velocity field in this type of flow. An infrared (IR) sensing array was used to capture the instantaneous free surface temperature field while two-dimensional velocity measurements in planes either perpendicular or parallel to the free surface were acquired using digital particle image velocimetry (DPIV). Data from two cases are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050330
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  • 9
    Electronic Resource
    Electronic Resource
    Prostaglandins Protect Human Intestinal Cells Against Ethanol Injury by Stabilizing Microtubules (Role of Protein Kinase C and Enhanced Calcium Efflux) (1999)
    Springer
    Digestive diseases and sciences 44 (1999), S. 697-707 
    Details
    ISSN: 1573-2568
    Keywords: CYTOPROTECTION ; DIMETHYL-PROSTAGLANDIN E2 ; PROTEIN KINASE C ; CALCIUM EFFLUX ; MICROTUBULES ; Caco-2 CELLS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prostaglandins (PG) protect gastrointestinalcells against damage induced by ethanol (EtOH) and othernoxious agents, a process termed cytoprotection. Thepresent study investigated the relationships between microtubule (MT) stability, protein kinase C(PKC) activation, and calcium efflux as a possiblemechanism of PG's protective action using a humancolonic cell line (Caco-2) exposed to known damagingconcentrations of EtOH (7.5% and 10% ). Preincubation ofCaco-2 cells with 16,16-dimethyl-PGE2 (PG,2.6 μM) significantly increased PKC activity in thesecells. Pretreatment of Caco-2 cells with 50 μM OAG (asynthetic diacylglycerol and PKC activator) or 30 nM TPA(a direct PKC activator) prior to exposure to 7.5% or10% EtOH for 5 min significantly reduced cell injury, asdetermined by trypan blue exclusion, and increased MT stability, as confirmed by confocalmicroscopy. Pretreatment of Caco-2 cells with 4alpha-PDD (an inactive phorbol ester, 20 nM) failed toprevent cell injury and disruption of the MTcytoskeleton. Preincubation with staurosporine (a PKC inhibitor, 3 nM)abolished the protective effects of PG in cells exposedto 7.5% and 10% EtOH. Incubation of Caco-2 cells withA23187 (a Ca2+ ionophore), similar to 10%EtOH, caused a significant reduction in cell viability andMT stability. Preincubation with A23187 in combinationwith PG or OAG prior to subsequent exposure to EtOHsignificantly abolished the protective effects of PG or OAG pretreatment. Finally, pretreatmentwith OAG, TPA, or PG resulted in significant increasesin calcium-45 efflux, which correlated with increasedstability of the MT cytoskeleton. These data suggest that PG possesses direct protective effectsagainst EtOH injury in Caco-2 cells and may act bystabilizing MT through the PKC signal transductionpathway and/or stimulation of calcium efflux from thecells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026649422607
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  • 10
    Electronic Resource
    Electronic Resource
    Contribution of nitric oxide to exercise-induced hypotension in human sympathetic denervation (1999)
    Springer
    Clinical autonomic research 9 (1999), S. 263-269 
    Details
    ISSN: 1619-1560
    Keywords: nitric oxide ; exercise ; sympathetic denervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The cardiovascular, catecholamine, and nitrate/nitrite (NOx) responses to bicycle exercise were measured in 14 normal subjects (controls) and two groups with sympathetic denervation; 14 with peripheral autonomic failure (pure autonomic failure [PAF]); and 13 with central autonomic failure (multiple system atrophy [MSA]). With exercise, blood pressure increased in control subjects by 40±7/24±5 mm Hg (p〈0.001) and fell in PAF by 24±8/24±5 mm Hg (p〈0.02 and p〈0.007) and MSA by 31±7/11±3 mm Hg (p〈0.005 and p〈0.04). With exercise, the increase in heart rate was greater in control subjects (60±3 to 111±4/min; p〈0.0001) than in PAF (69±3 to 86±4/min; p〈0.0001) and MSA (70±4 to 90±4; p〈0.001). Resting plasma noradrenaline levels were similar in controls (291±51 pg ml−1) and MSA (257±49 pg ml−1), but lower in PAF (82±14 pg ml−1). With exercise, plasma noradrenaline increased in controls but was unchanged in PAF and MSA. Resting NOx was similar in controls (50±5 nmol/L; range, 23.3–87.6 nmol/L) and PAF patients (59±8 nmol/l; range, 19.3–116.4 nmol/L), but was higher in MSA patients (87±14 nmol/L; p〈0.025, range 15.4–157.2 nmol/L). With exercise, NOx was unchanged in control subjects and increased by 10% and 17% in PAF and MSA, respectively; these changes were not statistically significant. This study suggests that circulating changes in NOx levels do not exert a major role in exercise-induced hypotension in subjects with sympathetic denervation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319456
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