37,162 research outputs found
Unethical aspects of homeopathic dentistry
In the last year there has been a great deal of public debate about homeopathy, the system of alternative medicine whose main principles are that like cures like and that potency increases relative to dilution. The House of Commons Select Committee on Science and Technology concluded in November 2009 that there is no evidence base for homeopathy, and agreed with some academic commentators that homeopathy should not be funded by the NHS. While homeopathic doctors and hospitals are quite commonplace, some might be surprised to learn that there are also many homeopathic dentists practising in the UK. This paper examines the statements made by several organisations on behalf of homeopathic dentistry and suggests that they are not entirely ethical and may be in breach of various professional guidelines
Determining the parameters in a social welfare function using stated preference data: an application to health
One way in which economists might determine how best to balance the competing objectives of efficiency and equity is to specify a social welfare function (SWF). This paper looks at how the stated preferences of a sample of the general public can be used to estimate the shape of the SWF in the domain of health benefits. The results suggest that it is possible to determine the parameters in a social welfare function from stated preference data, but show that people are sensitive to what inequalities exist and to the groups across which those inequalities exist
Exact and Asymptotic Weighted Logrank Tests for Interval Censored Data: The interval R Package
For right-censored data perhaps the most commonly used tests are weighted logrank tests, such as the logrank and Wilcoxon-type tests. In this paper we review several generalizations of those weighted logrank tests to interval-censored data and present an R package, interval, to implement many of them. The interval package depends on the perm package, also presented here, which performs exact and asymptotic linear permutation tests. The perm package performs many of the tests included in the already available coin package, and provides an independent validation of coin. We review analysis methods for interval-censored data, and we describe and show how to use the interval and perm packages.
The constrained modified KP hierarchy and the generalized Miura transformations
In this letter, we consider the second Hamiltonian structure of the
constrained modified KP hierarchy. After mapping the Lax operator to a pure
differential operator the second structure becomes the sum of the second and
the third Gelfand-Dickey brackets defined by this differential operator. We
simplify this Hamiltonian structure by factorizing the Lax operator into linear
terms.Comment: 8 pages, latex, no figure
Isochronal synchronization of delay-coupled systems
We consider small network models for mutually delay-coupled systems which
typically do not exhibit stable isochronally synchronized solutions. We show
that for certain coupling architectures which involve delayed self feedback to
the nodes, the oscillators become isochronally synchronized. Applications are
shown for both incoherent pump coupled lasers and spatio-temporal coupled fiber
ring lasers.Comment: 5 pages, accepted for publication in Physical Review
The H II Region/PDR Connection: Self-Consistent Calculations of Physical Conditions in Star-Forming Regions
We have performed a series of calculations designed to reproduce infrared
diagnostics used to determine physical conditions in star forming regions. We
self-consistently calculate the thermal and chemical structure of an H II
region and photodissociation region (PDR) that are in pressure equilibrium.
This differs from previous work, which used separate calculations for each gas
phase. Our calculations span a wide range of stellar temperatures, gas
densities, and ionization parameters. We describe improvements made to the
spectral synthesis code Cloudy that made these calculations possible. These
include the addition of a molecular network with ~1000 reactions involving 68
molecular species and improved treatment of the grain physics. Data from the
Spitzer First Look Survey, along with other archives, are used to derive
important physical characteristics of the H II region and PDR. These include
stellar temperatures, electron densities, ionization parameters, UV radiation
flux, and PDR density. Finally, we calculate the contribution of the H II
region to PDR emission line diagnostics, which allows for a more accurate
determination of physical conditions in the PDR.Comment: 60 pages, 35 figures, to be published in the Astrophysical Journal.
Version with full resolution is available at
http://www.pa.uky.edu/~nicholas/hii_pdr_high_res.pd
Laser Interferometer Gravitational-Wave Observatory beam tube component and module leak testing
Laser Interferometer Gravitational-Wave Observatory (LIGO) is a joint project of the California Institute of Technology and the Massachusetts Institute of Technology funded by the National Science Foundation. The project is designed to detect gravitational waves from astrophysical sources such as supernova and black holes. The LIGO project constructed observatories at two sites in the U.S. Each site includes two beam tubes (each 4 km long) joined to form an "L" shape. The beam tube is a 1.25 m diam 304 L stainless steel, ultrahigh vacuum tube that will operate at 1×10^–9 Torr or better. The beam tube was manufactured using a custom spiral weld tube mill from material processed to reduce the outgassing rate in order to minimize pumping costs. The integrity of the beam tube was assured by helium mass spectrometer leak testing each component of the beam tube system prior to installation. Each 2 km long, isolatable beam tube module was then leak tested after completion
(Super)twistors and (super)strings
The Lagrangian formulation of the D=4 bosonic string and superstring in terms
of the (super)twistors is considered. The (super)twistor form of the equations
of motion is derived and the kappa-symmetry transformation for the
supertwistors is given. It is shown that the covariant kappa-symmetry gauge
fixation results in the action quadratic in the (super)twistor variables.Comment: LaTeX, 17 page
The application of the scanning electron microscope to studies of current multiplication, avalanche breakdown and thermal runaway. Part 1 - General physical basis
Scanning electron microscope applications in study of current multiplication, avalanche breakdown, and thermal runaway - Physical basi
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