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  • Other Sources  (13)
  • 1995-1999  (7)
  • 1985-1989  (6)
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  • 1
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    Observations of blazars with ASCA (1996)
    In:  CASI
    Details
    Publication Date: 2004-12-03
    Description: The Advanced Satellite for Cosmology and Astrophysics (ASCA) observations of 3C 279, Mkn 421, PKS 2155-304, BL Lac 0716+714 and OJ 287 blazars are presented. Blazars are a class of active galactic nuclei characterized by high variability, high polarization, flat radio spectrum and featureless spectrum. The X-ray spectra and flux variations of blazars are discussed. The inverse correlation between X-ray flux and index, soft lag, the convex curvature of the spectrum, flat gamma-ray and/or X-ray spectra, fast variability and featureless spectrum are common characteristics of blazars.
    Keywords: Astronomy
    Type: ; 413-416
    Format: text
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  • 2
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    Gas exchange and CO2 flux in the tropical Atlantic Ocean determined from Rn-222 and pCO2 measurements (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The piston velocity for the tropical Atlantic Ocean has been determined from 29 radon profiles measured during the TTO Tropical Atlantic Study. By combining these data with the pCO2 data measured in the surface water and air samples, the net flux of CO2 across the sea-air interface has been calculated for the tropical Atlantic. The dependence of the piston velocity on wind speed is discussed, and possible causes for the high sea-to-air CO2 flux observed in the equatorial zone are examined.
    Keywords: OCEANOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 7005-702
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  • 3
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    Proportional drift tubes for large area muon detectors (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A proportional drift chamber which consists of eight rectangular drift tubes with cross section of 10 cm x 5 cm, a sense wire of 100 micron phi gold-plated tungsten wire and the length of 6 m, was tested using cosmic ray muons. Spatial resolution (rms) is between 0.5 and 1 mm over drift space of 50 mm, depending on incident angle and distance from sense wire.
    Keywords: SPACE RADIATION
    Type: HE-5.2-11 , 19th Intern. Cosmic Ray Conf - Vol. 8; p 65-68; NASA-CP-2376-VOL-8
    Format: application/pdf
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  • 4
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    High-energy multiple muons and heavy primary cosmic-rays (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Three-dimensional simulations were carried out on high-energy multiple muons. On the lateral spread, the comparison with the deep underground observations indicates that the primary cosmic rays include heavy nuclei of high content. A method to determine the average mass number of primary particles in the energy around 10 to the 15th power eV is suggested.
    Keywords: SPACE RADIATION
    Type: OG-5.2-9 , 19th Intern. Cosmic Ray Conf - Vol. 2; p 222-225; NASA-CP-2376-VOL-2
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  • 5
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    Far-infrared line intensities of H2O and CO from warm molecular clouds (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Takahashi et al. (1983) have studied the role of H2O in the overall energetics of warm molecular clouds with large optical depths. It was found that in molecular clouds associated with nearby or embedded luminosity sources, the dust is likely to be warmer than the molecular gas. Thus, the warm dust represents the primary source of heat for the gas. In some cases, H2O was found to cool the gas. Takahashi et al. (1983) have presented the formalism for treating H2O in an optically thick molecular cloud with embedded sources of luminosity. The total H2O heating and cooling rates were also calculated. In the present investigation, the emergent intensities of far-infrared lines of H2O and excited, rotational CO transitions from relatively warm molecular clouds based on the large-velocity gradient model of the previous study are calculated. It is found that the dominant submillimeter CO transitions are related to emission, while the H2O transitions can be either absorption or emission lines.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 292; 192-199
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  • 6
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    Comments on the measurements of multiple muon phenomena (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The extensive air showers in the energy around 10 to the 15th power eV include those initiated by astrophysical primary gamma-rays. The observations need a precise measurement on the directions of primary particles. It is one of the methods to measure the directions of high-energy muons in air showers. The accuracy in measuring the direction, by calculating the cosmic-ray phenomena in the atmosphere at very high energy was investgated. The results calculated by Monte Carlo method suggest that one may determine the direction of primary cosmic-rays within errors of 10/3 rad in observing muons of above 100 GeV at sea level.
    Keywords: SPACE RADIATION
    Type: HE-5.2-13 , 19th Intern. Cosmic Ray Conf - Vol. 8; p 73-76; NASA-CP-2376-VOL-8
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  • 7
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    The G1 restriction point as critical regulator of neocortical neuronogenesis (1999)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Neuronogenesis in the pseudostratified ventricular epithelium is the initial process in a succession of histogenetic events which give rise to the laminate neocortex. Here we review experimental findings in mouse which support the thesis that the restriction point of the G1 phase of the cell cycle is the critical point of regulation of the overall neuronogenetic process. The neuronogenetic interval in mouse spans 6 days. In the course of these 6 days the founder population and its progeny execute 11 cell cycles. With each successive cycle there is an increase in the fraction of postmitotic cells which leaves the cycle (the Q fraction) and also an increase in the length of the cell cycle due to an increase in the length of the G1 phase of the cycle. Q corresponds to the probability that postmitotic cells will exit the cycle at the restriction point of the G1 phase of the cell cycle. Q increases non-linearly, but the rate of change of Q with cycle (i.e., the first derivative) over the course of the neuronogenetic interval is a constant, k, which appears to be set principally by cell internal mechanisms which are species specific. Q also seems to be modulated, but at low amplitude, by a balance of mitogenic and antimitogenic influences acting from without the cell. We suggest that intracellular signal transduction systems control a general advance of Q during development and thereby determine the general developmental plan (i.e., cell number and laminar composition) of the neocortex and that external mitogens and anti-mitogens modulate this advance regionally and temporally and thereby produce regional modifications of the general plan.
    Keywords: Life Sciences (General)
    Type: Neurochemical research (ISSN 0364-3190); 24; 4; 497-506
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  • 8
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    Sequence of neuron origin and neocortical laminar fate: relation to cell cycle of origin in the developing murine cerebral wall (1999)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Neurons destined for each region of the neocortex are known to arise approximately in an "inside-to-outside" sequence from a pseudostratified ventricular epithelium (PVE). This sequence is initiated rostrolaterally and propagates caudomedially. Moreover, independently of location in the PVE, the neuronogenetic sequence in mouse is divisible into 11 cell cycles that occur over a 6 d period. Here we use a novel "birth hour" method that identifies small cohorts of neurons born during a single 2 hr period, i.e., 10-20% of a single cell cycle, which corresponds to approximately 1.5% of the 6 d neuronogenetic period. This method shows that neurons arising with the same cycle of the 11 cycle sequence in mouse have common laminar fates even if they arise from widely separated positions on the PVE (neurons of fields 1 and 40) and therefore arise at different embryonic times. Even at this high level of temporal resolution, simultaneously arising cells occupy more than one cortical layer, and there is substantial overlap in the distributions of cells arising with successive cycles. We demonstrate additionally that the laminar representation of cells arising with a given cycle is little if at all modified over the early postnatal interval of histogenetic cell death. We infer from these findings that cell cycle is a neuronogenetic counting mechanism and that this counting mechanism is integral to subsequent processes that determine cortical laminar fate.
    Keywords: Life Sciences (General)
    Type: The Journal of neuroscience : the official journal of the Society for Neuroscience (ISSN 0270-6474); 19; 23; 10357-71
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  • 9
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    A gradient in the duration of the G1 phase in the murine neocortical proliferative epithelium (1997)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Neuronogenesis in the neocortical pseudostratified ventricular epithelium (PVE) is initiated rostrolaterally and progresses caudo-medially as development progresses. Here we have measured the cytokinetic parameters and the fractional neuronal output parameter, Q, of laterally located early-maturing regions over the principal embryonic days (E12-E15) of neocortical neuronogenesis in the mouse. These measures are compared with ones previously made of a medial, late-maturing portion of the PVE. Laterally, as medially, the duration of the neuronogenetic interval is 6 days and comprises 11 integer cell cycles. Also, in both lateral and medial areas the length of G1 phase (TG1) increases nearly 4-fold and is the only cell cycle parameter to change. Q progresses essentially identically laterally and medially with respect to the succession of integer cell cycles. Most importantly, from E12 to E13 there is a steeply declining lateral to medial gradient in TG1. The gradient is due both to the lateral to medial graded stage of neuronogenesis and to the stepwise increase in TG1 with each integer cycle during the neuronogenetic interval. To our knowledge this gradient in TG1 of the cerebral PVE is the first cell biological gradient to be demonstrated experimentally in such an extensive proliferative epithelial sheet. We suggest that this gradient in TG1 is the cellular mechanism for positionally encoding a protomap of the neocortex within the PVE.
    Keywords: Life Sciences (General)
    Type: Cerebral cortex (New York, N.Y. : 1991) (ISSN 1047-3211); 7; 7; 678-89
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  • 10
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    Cyclin E-p27 opposition and regulation of the G1 phase of the cell cycle in the murine neocortical PVE: a quantitative analysis of mRNA in situ hybridization (1999)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We have analyzed the expression patterns of mRNAs of five cell cycle related proteins in the ventricular zone of the neocortical cerebral wall over the course of the neuronogenetic interval in the mouse. One set of mRNAs (cyclin E and p21) are initially expressed at high levels but expression then falls to a low asymptote. A second set (p27, cyclin B and cdk2) are initially expressed at low levels but ascend to peak levels only to decline again. These patterns divide the overall neuronogenetic interval into three phases. In phase 1 cyclin E and p21 levels of mRNA expression are high, while those of mRNAs of p27, cdk2 and cyclin B are low. In this phase the fraction of cells leaving the cycle after each mitosis, Q, is low and the duration of the G1 phase, TG1, is short. In phase 2 levels of expression of cyclin E and p21 fall to asymptote while levels of expression of mRNA of the other three proteins reach their peaks. Q increases to approach 0.5 and TG1 increases even more rapidly to approach its maximum length. In phase 3 levels of expression of cyclin E and p21 mRNAs remain low and those of the mRNAs of the other three proteins fall. TG1 becomes maximum and Q rapidly increases to 1.0. The character of these phases can be understood in part as consequences of the reciprocal regulatory influence of p27 and cyclin E and of the rate limiting functions of p27 at the restriction point and of cyclin E at the G1 to S transition.
    Keywords: Life Sciences (General)
    Type: Cerebral cortex (New York, N.Y. : 1991) (ISSN 1047-3211); 9; 8; 824-32
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