36,168 research outputs found
Strong coupling of magnons in a YIG sphere to photons in a planar superconducting resonator in the quantum limit
We report measurements of a superconducting coplanar waveguide resonator
(CPWR) coupled to a sphere of yttrium-iron garnet. The non-uniform CPWR field
allows us to excite various magnon modes in the sphere. Mode frequencies and
relative coupling strengths are consistent with theory. Strong coupling is
observed to several modes even with, on average, less than one excitation
present in the CPWR. The time response to square pulses shows oscillations at
the mode splitting frequency. These results indicate the feasibility of
combining magnonic and planar superconducting quantum devices.Comment: 5 pages, 4 figure
Lewis Research Center spin rig and its use in vibration analysis of rotating systems
The Lewis Research Center spin rig was constructed to provide experimental evaluation of analysis methods developed under the NASA Engine Structural Dynamics Program. Rotors up to 51 cm (20 in.) in diameter can be spun to 16,000 rpm in vacuum by an air motor. Vibration forcing functions are provided by shakers that apply oscillatory axial forces or transverse moments to the shaft, by a natural whirling of the shaft, and by an air jet. Blade vibration is detected by strain gages and optical blade-tip motion sensors. A variety of analogy and digital processing equipment is used to display and analyze the signals. Results obtained from two rotors are discussed. A 56-blade compressor disk was used to check proper operation of the entire spin rig system. A special two-blade rotor was designed and used to hold flat and twisted plates at various setting and sweep angles. Accurate Southwell coefficients have been obtained for several modes of a flat plate oriented parallel to the plane of rotation
Monetary costs of agitation in older adults with Alzheimer's disease in the UK: prospective cohort study
While nearly half of all people with Alzheimer's disease (AD) have agitation symptoms every month, little is known about the costs of agitation in AD. We calculated the monetary costs associated with agitation in older adults with AD in the UK from a National Health Service and personal social services perspective
Observers and Measurements in Noncommutative Spacetimes
We propose a "Copenhagen interpretation" for spacetime noncommutativity. The
goal is to be able to predict results of simple experiments involving signal
propagation directly from commutation relations. A model predicting an energy
dependence of the speed of photons of the order E/E_Planck is discussed in
detail. Such effects can be detectable by the GLAST telescope, to be launched
in 2006.Comment: 10 pp; v2: equivalence of observers explicitely stated; v3: minor
changes, references and remarks added, burst spreading with energy emphasized
as a signature rather than nois
The Economic Costs of Child Maltreatment in UK
Child maltreatment is a major public health problem with significant consequences for individual victims and for society. In this paper we quantify for the first time the economic costs of fatal and non-fatal child maltreatment in the UK in relation to several short-, medium- and long-term outcomes ranging from physical and mental health problems, to labour market outcomes and welfare use. We combine novel regression analysis of rich data from the National Child Development Study and the English Longitudinal Study of Ageing with secondary evidence to produce an incidence-based estimate of the lifetime costs of child maltreatment from a societal perspective. The discounted average lifetime incidence cost of non-fatal child maltreatment by a primary caregiver is estimated at £89,390 (95% uncertainty interval £44,896 to £145,508); the largest contributors to this are costs from social care, short-term health and long-term labour market outcomes. The discounted lifetime cost per death from child maltreatment is estimated at £940,758, comprising health care and lost productivity costs. Our estimates provide the first comprehensive benchmark to quantify the costs of child maltreatment in the UK and the benefits of interventions aimed at reducing or preventing it
The economic costs of child maltreatment in the UK
Child maltreatment is a major public health problem with significant consequences for individual victims and for society. In this paper, we quantify for the first time the economic costs of fatal and nonfatal child maltreatment in the UK in relation to several short-, medium-, and long-term outcomes ranging from physical and mental health problems to labor market outcomes and welfare use. We combine novel regression analysis of rich data from the National Child Development Study and the English Longitudinal Study of Aging with secondary evidence to produce an incidence-based estimate of the lifetime costs of child maltreatment from a societal perspective. The discounted average lifetime incidence cost of nonfatal child maltreatment by a primary caregiver is estimated at £89,390 (95% uncertainty interval £44,896 to £145,508); the largest contributors to this are costs from social care, short-term health, and long-term labor market outcomes. The discounted lifetime cost per death from child maltreatment is estimated at £940,758, comprising health care and lost productivity costs. Our estimates provide the first comprehensive benchmark to quantify the costs of child maltreatment in the UK and the benefits of interventions aimed at reducing or preventing it
Spitzer/IRAC Observations of the Variability of Sgr A* and the Object G2 at 4.5 microns
We present the first detection from the Spitzer Space Telescope of 4.5 micron
variability from Sgr A*, the emitting source associated with the Milky Way's
central black hole. The >23 hour continuous light curve was obtained with the
IRAC instrument in 2013 December. The result characterizes the variability of
Sgr A* prior to the closest approach of the G2 object, a putative infalling gas
cloud that orbits close to Sgr A*. The high stellar density at the location of
Sgr A* produces a background of ~250 mJy at 4.5 microns in each pixel with a
large pixel-to-pixel gradient, but the light curve for the highly variable Sgr
A* source was successfully measured by modeling and removing the variations due
to pointing wobble. The observed flux densities range from the noise level of
~0.7 mJy rms in a 6.4-s measurement to ~10 mJy. Emission was seen above the
noise level ~34% of the time. The light curve characteristics, including the
flux density distribution and structure function, are consistent with those
previously derived at shorter infrared wavelengths. We see no evidence in the
light curve for activity attributable to the G2 interaction at the observing
epoch, ~100 days before the expected G2 periapsis passage. The IRAC light curve
is more than a factor of two longer than any previous infrared observation,
improving constraints on the timescale of the break in the power spectral
distribution of Sgr A* flux densities. The data favor the longer of the two
previously published values for the timescale.Comment: 13 pages, 10 figures, 2 tables, accepted for publication in the Ap
The time travel paradox
We define the time travel paradox in physical terms and prove its existence
by constructing an explicit example. We argue further that in theories -- such
as general relativity -- where the spacetime geometry is subject to nothing but
differential equations and initial data no paradoxes arise.Comment: Minor changes + an explanatory note concerning the lions with the
same world line
Spiral Defect Chaos in Large Aspect Ratio Rayleigh-Benard Convection
We report experiments on convection patterns in a cylindrical cell with a
large aspect ratio. The fluid had a Prandtl number of approximately 1. We
observed a chaotic pattern consisting of many rotating spirals and other
defects in the parameter range where theory predicts that steady straight rolls
should be stable. The correlation length of the pattern decreased rapidly with
increasing control parameter so that the size of a correlated area became much
smaller than the area of the cell. This suggests that the chaotic behavior is
intrinsic to large aspect ratio geometries.Comment: Preprint of experimental paper submitted to Phys. Rev. Lett. May 12
1993. Text is preceeded by many TeX macros. Figures 1 and 2 are rather lon
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