37,299 research outputs found
ERTS-1 observations of sea surface circulation and sediment transport, Cook Inlet, Alaska
Cook Inlet is a large tide-dominated estuary in southern Alaska. Highly turbid streams enter the upper inlet, providing an excellent tracer for circulation in the lower inlet. MSS 4 and 5 images both can be used in this area to plot sediment and pollutant trajectories, areas of (probable) commercial fish concentration, and the entire circulation regime
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Effective Temperature Of Uranus
NASA NGR 09-015-047, NGR 22-007-270, NGR 44-012-152Astronom
Do Childhood Vaccines Have Non-Specific Effects on Mortality
A recent article by Kristensen et al. suggested that measles vaccine and bacille CalmetteâGuĂ©rin (BCG) vaccine might\ud
reduce mortality beyond what is expected simply from protection against measles and tuberculosis. Previous reviews of the potential effects of childhood vaccines on mortality have not considered methodological features of reviewed studies. Methodological considerations play an especially important role in observational assessments, in which selection factors for vaccination may be difficult to ascertain. We reviewed 782 English language articles on vaccines and childhood mortality and found only a few whose design met the criteria for methodological rigor. The data reviewed suggest that measles vaccine delivers its promised reduction in mortality, but there is insufficient evidence to suggest a mortality benefit above that caused by its effect on measles disease and its sequelae. Our review of the available data in the literature reinforces how difficult answering these considerations has been and how important study design will be in determining the effect of specific vaccines on all-cause mortality.\u
Angular Power Spectrum of the Microwave Background Anisotropy seen by the COBE Differential Microwave Radiometer
The angular power spectrum estimator developed by Peebles (1973) and Hauser &
Peebles (1973) has been modified and applied to the 2 year maps produced by the
COBE DMR. The power spectrum of the real sky has been compared to the power
spectra of a large number of simulated random skies produced with noise equal
to the observed noise and primordial density fluctuation power spectra of power
law form, with . Within the limited range of spatial scales
covered by the COBE DMR, corresponding to spherical harmonic indices 3 \leq
\ell \lsim 30, the best fitting value of the spectral index is with the Harrison-Zeldovich value approximately
0.5 below the best fit. For 3 \leq \ell \lsim 19, the best fit is . Comparing the COBE DMR at small to
the at from degree scale anisotropy experiments
gives a smaller range of acceptable spectral indices which includes .Comment: 22 pages of LaTex using aaspp.sty and epsf.sty with appended
Postscript figures, COBE Preprint 94-0
ISOCAM spectro-imaging of the H2 rotational lines in the supernova remnant IC443
We report spectro-imaging observations of the bright western ridge of the
supernova remnant IC 443 obtained with the ISOCAM circular variable filter
(CVF) on board the Infrared Space Observatory (ISO). This ridge corresponds to
a location where the interaction between the blast wave of the supernova and
ambient molecular gas is amongst the strongest. The CVF data show that the 5 to
14 micron spectrum is dominated by the pure rotational lines of molecular
hydrogen (v = 0--0, S(2) to S(8) transitions). At all positions along the
ridge, the H2 rotational lines are very strong with typical line fluxes of
10^{-4} to 10^{-3} erg/sec/cm2/sr. We compare the data to a new time-dependent
shock model; the rotational line fluxes in IC 443 are reproduced within factors
of 2 for evolutionary times between 1,000 and 2,000 years with a shock velocity
of 30 km/sec and a pre-shock density of 10^4 /cm3.Comment: To appear in Astronomy and Astrophysic
Form Factors from a Relativistic Dynamical Model of Pion Electroproduction
We obtain the electromagnetic form factors of the transition
by analyzing recent pion-electroproduction data using a fully relativistic
dynamical model. Special care is taken to satisfy Ward-Takahashi identities for
the Born term in the presence of form factors thereby allowing the use of
realistic electromagnetic form factors of the nucleon and pion. We parametrize
the dependence of the {\it bare} form factors by a
three-parameter form which is consistent with the asymptotic behavior inferred
from QCD. The parameters of the bare form factors are the
only free parameters of the model and are fitted to the differential
cross-section and multipole-analysis data up to (GeV/c) in the
-resonance region. This analysis emphasizes the significance of
the pion-cloud effects in the extraction of the resonance parameters.Comment: 9 pages, 5 figures, several small corrections, to be published in
Phys. Rev.
A balloon-borne 1 meter telescope for far-infrared astronomy
The flight of a balloon-borne one-meter telescope for infrared astronomy in the wavelength interval of 40 to 240 microns is discussed. The gyro-stabilized telescope mapped the intensity of the far infrared radiation from NGC 7538, Mars, the Orion Nebula, and W3 with a resolution of one minute and from selected regions of these sources with a resolution of 30 seconds. The infrared detection is described and its capabilities are analyzed. The instrumentation, orientation system, and modes of observation of the telescope are defined
Search For Unresolved Sources In The COBE-DMR Two-Year Sky Maps
We have searched the temperature maps from the COBE Differential Microwave
Radiometers (DMR) first two years of data for evidence of unresolved sources.
The high-latitude sky (|b| > 30\deg) contains no sources brighter than 192 uK
thermodynamic temperature (322 Jy at 53 GHz). The cumulative count of sources
brighter than threshold T, N(> T), is consistent with a superposition of
instrument noise plus a scale-invariant spectrum of cosmic temperature
fluctuations normalized to Qrms-PS = 17 uK. We examine the temperature maps
toward nearby clusters and find no evidence for any Sunyaev-Zel'dovich effect,
\Delta y < 7.3 x 10^{-6} (95% CL) averaged over the DMR beam. We examine the
temperature maps near the brightest expected radio sources and detect no
evidence of significant emission. The lack of bright unresolved sources in the
DMR maps, taken with anisotropy measurements on smaller angular scales, places
a weak constraint on the integral number density of any unresolved
Planck-spectrum sources brighter than flux density S, n(> S) < 2 x 10^4 (S/1
Jy)^{-2} sr^{-1}.Comment: 16 pages including 2 figures, uuencoded PostScript, COBE preprint
94-0
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