6,860 research outputs found
General Semiparametric Shared Frailty Model Estimation and Simulation with frailtySurv
The R package frailtySurv for simulating and fitting semi-parametric shared
frailty models is introduced. Package frailtySurv implements semi-parametric
consistent estimators for a variety of frailty distributions, including gamma,
log-normal, inverse Gaussian and power variance function, and provides
consistent estimators of the standard errors of the parameters' estimators. The
parameters' estimators are asymptotically normally distributed, and therefore
statistical inference based on the results of this package, such as hypothesis
testing and confidence intervals, can be performed using the normal
distribution. Extensive simulations demonstrate the flexibility and correct
implementation of the estimator. Two case studies performed with publicly
available datasets demonstrate applicability of the package. In the Diabetic
Retinopathy Study, the onset of blindness is clustered by patient, and in a
large hard drive failure dataset, failure times are thought to be clustered by
the hard drive manufacturer and model
A quantitative investigation of the effect of a close-fitting superconducting shield on the coil-factor of a solenoid
Superconducting shields are commonly used to suppress external magnetic
interference. We show, that an error of almost an order of magnitude can occur
in the coil-factor in realistic configurations of the solenoid and the shield.
The reason is that the coil-factor is determined by not only the geometry of
the solenoid, but also the nearby magnetic environment. This has important
consequences for many cryogenic experiments involving magnetic fields such as
the determination of the parameters of Josephson junctions, as well as other
superconducting devices. It is proposed to solve the problem by inserting a
thin sheet of high-permeability material, and the result numerically tested.Comment: 3 pages, 4 figures, submitted to AP
Delivery, Beam and Range Monitoring in Particle Therapy in a Highly Innovative Integrated Design
There\u27s No End to My Love For You
Photo of couple holding one anotherhttps://scholarsjunction.msstate.edu/cht-sheet-music/3239/thumbnail.jp
I\u27ll Sit Right On The Moon : And Keep My Eyes On You
https://digitalcommons.library.umaine.edu/mmb-vp/3593/thumbnail.jp
Spontaneous Fluxoid Formation in Superconducting Loops
We report on the first experimental verification of the Zurek-Kibble scenario
in an isolated superconducting ring over a wide parameter range. The
probability of creating a single flux quantum spontaneously during the fast
normal-superconducting phase transition of a wide Nb loop clearly follows an
allometric dependence on the quenching time , as one would expect if
the transition took place as fast as causality permits. However, the observed
Zurek-Kibble scaling exponent is two times larger than
anticipated for large loops. Assuming Gaussian winding number densities we show
that this doubling is well-founded for small annuli.Comment: 10 pages, 2 figures, submitted to Phys. Rev. Lett
A Novel Hybrid Microdosimeter for Radiation Field Characterization Based on the Tissue Equivalent Proportional Counter Detector and Low Gain Avalanche Detectors Tracker: A Feasibility Study
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