503 research outputs found
Experiment Luxembourg
The earlier orbits and ephemerides for the Soviet satellites were not sufficiently
accurate to be very useful in making observations in Alaska. Extrapolations
from our own observations gave better predictions. This merely pointed out the fact
that rough observations of meridian transits at high latitudes will give better values
of the inclination of the orbit than precision observations at low latitudes. Hence,
it was decided to observe visually the meridian transits estimating the altitude by
noting the position with respect to the stars or using crude alidade measurements.
The times of the earlier observations were observed on a watch or clock and the clock
correction obtained from WWV. Later the times were determined with the aid of stop
watches, taking time intervals from WWV signals.
This rather meager program of optical observations of the Soviet satellites was
undertaken to give supplementary data for use of the radio observations, and particularly
to assist in the prediction of position of the satellite so that the 61-foot
radar of Stanford Research Institute could be set accurately enough to observe it
(the beam width at the half-power points is about 3°).
This report contains primarily the visual observations made at the Geophysical
Institute by various members of the staff, and a series of observations by Olaf
Halverson at Nome, Alaska. In addition there is a short discussion of the geometry
of the trajectory, the illumination of a circumpolar satellite, and a note on the
evaluation of Brouwer's moment factors.The research reported In this document has been sponsored by
the Geophysics Research Directorate of the Air Force Cambridge
Research Center* Air Research and Development Command, under
Contract AF 19(604)-3880.List of Figures -- Introduction -- Present knowledge of the electron densities and collision frequencies in the D region of the ionosphere. -- The theory of radio wave interaction. -- The outline of the planned experiment. -- Some comments about the planned experiment.
Some comments about gyrointeraction. -- Conclusion -- Acknowledgements -- ReferencesYe
Experiment Luxembourg, Scientific Report No. 3
Contract No. AF 19(604)-3860 --
GEOPHYSICS RESEARCH DIRECTORATE AIR FORCE CAMBRIDGE RESEARCH CENTER AIR RESEARCH AND DEVELOPMENT COMMAND UNITED STATES AIR FORCE; BEDFORD, MASSACHUSETTSLIST OF FIGURES -- ABSORPTION OF RADIO WAVES AND METEORIC IONIZATION -- METEORIC IONIZATION -- ABSORPTION AND SPORADIC METEORS -- ABSORPTION AND METEOR SHOWERS -- IONIZING EFFICIENCY OF METEORS -- CONCLUSIONS -- ACKNOWLEDGEMENTS -- REFERENCESYe
Dynamics of the peel front and the nature of acoustic emission during peeling of an adhesive tape
We investigate the peel front dynamics and acoustic emission of an adhesive
tape within the context of a recent model by including an additional
dissipative energy that mimics bursts of acoustic signals. We find that the
nature of the peeling front can vary from smooth to stuck-peeled configuration
depending on the values of dissipation coefficient, inertia of the roller, mass
of the tape. Interestingly, we find that the distribution of AE bursts shows a
power law statistics with two scaling regimes with increasing pull velocity as
observed in experiments. In this regimes, the stuck-peeled configuration is
similar to the `edge of peeling' reminiscent of a system driven to a critical
state.Comment: Accepted for publication in Phys. Rev. Let
Experiment Luxembourg, Scientific Report No. 4
Experiment Luxembourg was designed to measure the
electron density and electron collision-frequency as a
function of height in the D region over College, Alaska
using the technique of radio-wave interaction. A block
diagram, which includes all the equipment necessary for
the actual operation of the experiment, is described
and illustrated in detail. The major parts of the system
are: the disturbing transmitter operating on 17.5
Mc/s and using a 4x4 array of Yagi antennas, the wanted
transmitter operating on ~ 5 Mc/s and using a circular
polarization unit with 4 dipoles arranged in a quadrangle,
a similar circular polarization unit and antenna
for 5 Mc/s at the receiving site, and the delicate
receiving system which detects a cross-modulation of
1x10 -4 for a one volt input signal. Some values of
electron density and collision-frequency have been obtained
and will be discussed in following publications.Contract No. AF 19(604)-3880 -- GEOPHYSICS RESEARCH DIRECTORATE AIR FORCE CAMBRIDGE RESEARCH LABORATORIES AIR FORCE RESEARCH DIVISION (ARDC)
UNITED STATES AIR FORCE BEDFORD, MASSACHUSETTSLIST OP FIGURES -- ABSTRACT -- INTRODUCTION -- TRANSMITTING SITE : Timer
Wanted transmitter ; Circular polarization unit ; 5 Mc/s antenna ; Disturbing transmitter ; Duplexer ; 17.5 Mc/s receiver ; 17.5 Mc/s antenna -- RECEIVING SITE : 5 Mc/s antenna ; Circular polarization unit ; 5 Mc/s Super-pro receiver ; Wide band IF amplifier ; Pulse shaper and delay control ; Receiver gate and reference signal generator ; Signal gate ; Selective amplifier ; Phase sensitive detector ; E.A. recorder ; 17.5 Mc/s Collins receiver ; Scope unit ; Calibration -- Results -- AcknowledgementsYe
Recommended from our members
Induction of T-cell mitogenic unresponsiveness by recombinant human granulocyte colony-stimulating factor (rHuG-CSF)
Obturations en amalgame et modifications des lymphocytes T
Dental amalgam and nickel alloys have been considered quite safe. Previous authors reported the effect of dental amalgam and nickel alloys on human T-lymphocytes modifications after amalgam dental fillings, into dose-dependence of any modifications and into possible temporary.Eight patients were subjected to dental care with amalgam dental fillings. Drawings of blood were executed at start, fifteen days after late fillings and two months later.The results about modifications of T-lymphocytes were not univocal. We believe, at now, that temporary modifications of the immunity seem to be related to a cytotoxic mechanism.Les auteurs ont étudié les modifications systémiques des lymphocytes T (T3) et des sous-populations T4 et T8 après la pose d’obturations en amalgame. Les résultats ne sont pas univoques et leur interprétation n’est pas facile.On pense que l’amalgame dentaire pourrait provoquer une modification transitoire et temporaire des défenses immunitaires par un mécanisme de cytotoxicité
Missing physics in stick-slip dynamics of a model for peeling of an adhesive tape
It is now known that the equations of motion for the contact point during
peeling of an adhesive tape mounted on a roll introduced earlier are singular
and do not support dynamical jumps across the two stable branches of the peel
force function. By including the kinetic energy of the tape in the Lagrangian,
we derive equations of motion that support stick-slip jumps as a natural
consequence of the inherent dynamics. In the low mass limit, these equations
reproduce solutions obtained using a differential-algebraic algorithm
introduced for the earlier equations. Our analysis also shows that mass of the
ribbon has a strong influence on the nature of the dynamics.Comment: Accepted for publication in Phys. Rev. E (Rapid Communication
Quarterly Progress Reports Nos. 1-5, 7, 8
This report, prepared during May 1958, summarizes the analysis of over twelve months of amplitude and angular scintillation data obtained using phase-switch interferometers at 223 Mc and 456 Mc on the Cygnus and
Cassiopeia radio sources. The main parameters of the equipment used are
first discussed. The method of scaling the records, involving the arbitrary
division of the records into four (456 Mc) or six (223 Mc) levels of activity
is then described. The probability distributions of the amplitude variations,
as derived using a phase-sweep interferometer, are given for the main levels
of scintillation activity at 223 Mc. Values of mean fractional deviation of
power, -A.P. } for the main levels of activity at 223 Mc are also given.
Preliminary probability distributions of angular deviation, and values of
mean angular deviation, are also given for the different levels of activity
at 223 Mc. The solar-time dependence and sidereal-time (elevation angle)
dependence of the scintillation activity are presented arid c6mpared with
similar data from temperate latitudes. The report concludes with a section
in which a recent theory of radio star scintillations^ is modified to
include the effect of an elongation of the irregularities along the earth's
magnetic lines of force.Air Force Contract No. AF 30(635)-2837
Project No. 5535 - Task 45774
Rome Air Development Center, Griffiss Air Force Base
Rome, New YorkTABLE OF CONTENTS -- ABSTRACT -- [SECTION I] The Phase-Switch Interferometers : Main Parameters of the Equipment ; Method of Operation -- [SECTION II] Analysis of Phase-Switch Interferometer Records : Scaling of Records ; Probability of Occurrence of Different Indexes of Scintillation Activity ; Preparation of Monthly Diurnal Curve of the Mean Value A? at 223 Mc. ; Preparation of Mean Solar Time and Sidereal Time Variation of Mean -AP. at 223 Mc. ; Solar Time Dependence of the Mean Values of -4£ at 223 Mc. ; Sidereal Time Dependence of 223 Me Scintillation Activity -- Analysis of Angular Scintillation Information -- [SECTION III] Discussion of Results [SECTION IV] Adaptation to an Anisotropic Ionosphere of
Booker's Formulae for Radio Star Scintillations -- [SECTION V] Proposed Program of Further Research [SUMMARY] [REFERENCES]Ye
Power Laws, Precursors and Predictability During Failure
We investigate the dynamics of a modified Burridge-Knopoff model by
introducing a dissipative term to mimic the bursts of acoustic emission (AE)
from rock samples. The model explains many features of the statistics of AE
signals observed in experiments such as the crossover in the exponent value
from relatively small amplitude AE signals to larger regime, and their
dependence on the pulling speed. Significantly, we find that the cumulative
energy dissipated identified with acoustic emission can be used to predict a
major slip event. We also find a data collapse of the acoustic activity for
several major slip events describable by a universal stretched exponential with
corrections in terms of time-to-failure.Comment: 7 pages, 6 figures, Final version with minor change
Early Biomarkers and Intervention Programs for the Infant Exposed to Prenatal Stress
Functional development of affective and reward circuits, cognition and
response inhibition later in life exhibits vulnerability periods during
gestation and early childhood. Extensive evidence supports the model that
exposure to stressors in the gestational period and early postnatal life
increases an individual's susceptibility to future impairments of functional
development. Recent versions of this model integrate epigenetic mechanisms of
the developmental response. Their understanding will guide the future treatment
of the associated neuropsychiatric disorders. A combination of non-invasively
obtainable physiological signals and epigenetic biomarkers related to the
principal systems of the stress response, the Hypothalamic-Pituitary axis (HPA)
and the Autonomic Nervous System (ANS), are emerging as the key predictors of
neurodevelopmental outcomes. Such electrophysiological and epigenetic
biomarkers can prove to timely identify children benefiting most from early
intervention programs. Such programs should ameliorate future disorders in
otherwise apparently healthy children. The recently developed Early
Family-Centered Intervention Programs aim to influence the care and stimuli
provided daily by the family and improving parent/child attachment, a key
element for healthy socio-emotional adult life. Although frequently
underestimated, such biomarker-guided early intervention strategy represents a
crucial first step in the prevention of future neuropsychiatric problems and in
reducing their personal and societal impact.Comment: 18 pages-Revie
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