11,935 research outputs found
An Investigation of Whistlers and Chorus at High Latitudes
The whistlers and chorus received at College, Alaska during the period
from December 1955 through March 1958 are studied particularly with respect
to temporal variations.
The diurnal curves for whistler activity show maxima after midnight
local time while the seasonal variation peaks during the winter. It appears
that these variations in whistler activity are in part explainable in
terms of very low frequency propagation conditions.
The diurnal variation of chorus shows a maximum at about 1400 hours
local time. By the use of data from lower latitude stations a dependence
of this time of diurnal maximum on the geomagnetic latitude of the station
is shown.
The coefficients of correlation for chorus activity versus magnetic
activity were determined on a monthly basis. A seasonal variation in these
correlations is indicated which appears to be unique for the geomagnetic
latitude of College.
A preliminary statistical study of one of the more easily measured
characteristics of chorus is discussed. The characteristic chosen is the
mid-frequency in an element of chorus. A diurnal variation in this parameter
is indicated.The research reported in this document has been sponsored by
the Electronic Research Directorate of the Air Force Cambridge
Research Center, Air Research and Development Command, Air Force Research Contract No. AF 19(604)-1859Figures -- Abstract -- Introduction -- Instrumentation -- Observations -- Analysis - Whistlers -- Analysis - Chorus -- Discussion -- Acknowledgement -- ReferencesYe
Studies for space experiment development Final report
Development and selection of experiments to be performed during space mission
A Construction of Killing Spinors on S^n
We derive simple general expressions for the explicit Killing spinors on the
n-sphere, for arbitrary n. Using these results we also construct the Killing
spinors on various AdS x Sphere supergravity backgrounds, including AdS_5 x
S^5$, AdS_4 x S^7 and AdS_7 x S^4. In addition, we extend previous results to
obtain the Killing spinors on the hyperbolic spaces H^n.Comment: 11 pages, LaTe
The 70 S monosome accumulation and in vitro initiation complex formation by Escherichia coli ribosomes at 5 C
The inhibition of translation which is observed after shifting Escherichia coli to low temperature was investigated. 70 S ribosomes were isolated from E. coli 8 hours after a shift to 5 C synthesized protein in the absence of added mRNA (i.e., endogenous protein synthesis by 70 S monosomes) at a rate which was three times greater than the rate of endogenous protein synthesis by 70 S ribosomes which were isolated at the time of the shift to 5 C. Calculations based on the rates of endogenous protein synthesis and polyphenylalanine synthesis indicate that 70 S monosomes comprise only 0.1% of the total E. coli 70 S ribosome population after 8 hours at 5 c. Experiments designed to test initiation complex formation on ApUpG or formaldehyde treated MS-2 viral RNA demonstrated that, although the rate of formation of 30 S initiation complexes was not inhibited, the rate of formation of active 70 S initiation complexes, able to react with puromycin, was inhibited to a great extent at 5 C. A model depicting the effects of low temperature on the E. coli translation system is proposed
Yang-Mills-Chern-Simons Supergravity
N=(1,0) supergravity in six dimensions admits AdS_3\times S^3 as a vacuum
solution. We extend our recent results presented in hep-th/0212323, by
obtaining the complete N=4 Yang-Mills-Chern-Simons supergravity in D=3, up to
quartic fermion terms, by S^3 group manifold reduction of the six dimensional
theory. The SU(2) gauge fields have Yang-Mills kinetic terms as well as
topological Chern-Simons mass terms. There is in addition a triplet of matter
vectors. After diagonalisation, these fields describe two triplets of
topologically-massive vector fields of opposite helicities. The model also
contains six scalars, described by a GL(3,R)/SO(3) sigma model. It provides the
first example of a three-dimensional gauged supergravity that can obtained by a
consistent reduction of string-theory or M-theory and that admits AdS_3 as a
vacuum solution. There are unusual features in the reduction from
six-dimensional supergravity, owing to the self-duality condition on the 3-form
field. The structure of the full equations of motion in N=(1,0) supergravity in
D=6 is also elucidated, and the role of the self-dual field strength as torsion
is exhibited.Comment: Latex, 22 pages, hep-th number correcte
General Kerr-NUT-AdS Metrics in All Dimensions
The Kerr-AdS metric in dimension D has cohomogeneity [D/2]; the metric
components depend on the radial coordinate r and [D/2] latitude variables \mu_i
that are subject to the constraint \sum_i \mu_i^2=1. We find a coordinate
reparameterisation in which the \mu_i variables are replaced by [D/2]-1
unconstrained coordinates y_\alpha, and having the remarkable property that the
Kerr-AdS metric becomes diagonal in the coordinate differentials dy_\alpha. The
coordinates r and y_\alpha now appear in a very symmetrical way in the metric,
leading to an immediate generalisation in which we can introduce [D/2]-1 NUT
parameters. We find that (D-5)/2 are non-trivial in odd dimensions, whilst
(D-2)/2 are non-trivial in even dimensions. This gives the most general
Kerr-NUT-AdS metric in dimensions. We find that in all dimensions D\ge4
there exist discrete symmetries that involve inverting a rotation parameter
through the AdS radius. These symmetries imply that Kerr-NUT-AdS metrics with
over-rotating parameters are equivalent to under-rotating metrics. We also
consider the BPS limit of the Kerr-NUT-AdS metrics, and thereby obtain, in odd
dimensions and after Euclideanisation, new families of Einstein-Sasaki metrics.Comment: Latex, 24 pages, minor typos correcte
An ingestible temperature-transmitter
Pill-sized transmitter measures deep body temperature in studies of circadian rhythm and indicates general health. Ingestible device is a compromise between accuracy, circuit complexity, size and transmission range
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