81,634 research outputs found
Quantifying Absorption in the Transactional Interpretation
The Transactional Interpretation offers a solution to the measurement problem
by identifying specific physical conditions precipitating the non-unitary
`measurement transition' of von Neumann. Specifically, the transition occurs as
a result of absorber response (a process lacking in the standard approach to
the theory). The purpose of this Letter is to make clear that, despite recent
claims to the contrary, the concepts of `absorber' and `absorber response,' as
well as the process of absorption, are physically and quantitatively
well-defined in the transactional picture. In addition, the Born Rule is
explicitly derived for radiative processes.Comment: Final version, accepted in International Journal of Quantum
Foundation
A Deep Survey of HI-Selected Galaxies: The Sample and the Data
In a 21 cm neutral hydrogen survey of approximately 55 sq deg out to a
redshift of cz=8340 km/s, we have identified 75 extragalactic HI sources. These
objects comprise a well-defined sample of extragalactic sources chosen by means
that are independent of optical surface brightness selection effects. In this
paper we describe the Arecibo survey procedures and HI data, follow-up VLA HI
observations made of several unusual sources, and Kitt Peak B-, R-, and I-band
photometry for nearly all of the galaxies. We have also gathered information
for some of the optically detected galaxies within the same search volume. We
examine how samples generated by different types of search techniques overlap
with selection by HI flux. Only the least massive HI object, which is among the
lowest mass HI sources previously found, does not have a clear optical
counterpart, but a nearby bright star may hide low surface brightness emission.
However the newly-detected systems do have unusual optical properties. Most of
the 40 galaxies that were not previously identified in magnitude-limited
catalogs appear to be gas-dominated systems, and several of these systems have
HI mass-to-light ratios among the largest values ever previously found. These
gas-dominated objects also tend to have very blue colors, low surface
brightnesses, and no central bulges, which correlate strongly with their
relative star-to-gas content.Comment: 48 pages, 10 figures, Figure 3 included as 3 separate JPG images. To
appear in Ap J Supplement
Robust option replication for a Black-Scholes model extended with nondeterministic trends
Statistical analysis on various stocks reveals long range dependence behavior of the stock prices that is not consistent with the classical Black and Scholes model. This memory or nondeterministic trend behavior is often seen as a reflection of market sentiments and causes that the historical volatility estimator becomes unreliable in practice. We propose an extension of the Black and Scholes model by adding a term to the original Wiener term involving a smoother process which accounts for these effects. The problem of arbitrage will be discussed. Using a generalized stochastic integration theory [8], we show that it is possible to construct a self financing replicating portfolio for a European option without any further knowledge of the extension and that, as a consequence, the classical concept of volatility needs to be re-interpreted.
AMS subject classifications: 60H05, 60H10, 90A09
High fat diet causes rebound weight gain
Acknowledgements This work was funded by a grant from Action Medical Research (SP4581). We are grateful to the animal house staff for looking after the animals.Peer reviewedPublisher PD
The Higgs Boson Mass from Precision Electroweak Data
We present a new global fit to precision electroweak data, including new low-
and high-energy data and analyzing the radiative corrections arising from the
minimal symmetry breaking sectors of the Standard Model (SM) and its
supersymmetric extension (MSSM). It is shown that present data favor a Higgs
mass of O(M_Z): M_H = 76+152-50 GeV. We confront our analysis with
(meta)stability and perturbative bounds on the SM Higgs mass, and the
theoretical upper bound on the MSSM Higgs mass. Present data do not
discriminate significantly between the SM and MSSM Higgs mass ranges. We
comment in passing on the sensitivity of the Higgs mass determination to the
values of alpha(M_Z) and alpha_s(M_Z).Comment: 10 pages, latex, 8 figures as uu-encoded postscript fil
Microwave cavity light shining through a wall optimization and experiment
It has been proposed that microwave cavities can be used in a photon
regeneration experiment to search for hidden sector photons. Using two isolated
cavities, the presence of hidden sector photons could be inferred from a 'light
shining through a wall' phenomenon. The sensitivity of the experiment has
strong a dependence on the geometric construction and electromagnetic mode
properties of the two cavities. In this paper we perform an in depth
investigation to determine the optimal setup for such an experiment. We also
describe the results of our first microwave cavity experiment to search for
hidden sector photons. The experiment consisted of two cylindrical copper
cavities stacked axially inside a single vacuum chamber. At a hidden sector
photon mass of 37.78 micro eV we place an upper limit on the kinetic mixing
parameter chi = 2.9 * 10^(-5). Whilst this result lies within already
established limits our experiment validates the microwave cavity `light shining
through a wall' concept. We also show that the experiment has great scope for
improvement, potentially able to reduce the current upper limit on the mixing
parameter chi by several orders of magnitude.Comment: To be published in PR
Durability and damage tolerance of Large Composite Primary Aircraft Structure (LCPAS)
Analysis and testing addressing the key technology areas of durability and damage tolerance were completed for wing surface panels. The wing of a fuel-efficient, 200-passenger commercial transport airplane for 1990 delivery was sized using graphite-epoxy materials. Coupons of various layups used in the wing sizing were tested in tension, compression, and spectrum fatigue with typical fastener penetrations. The compression strength after barely visible impact damage was determined from coupon and structural element tests. One current material system and one toughened system were evaluated by coupon testing. The results of the coupon and element tests were used to design three distinctly different compression panels meeting the strength, stiffness, and damage-tolerance requirements of the upper wing panels. These three concepts were tested with various amounts of damage ranging from barely visible impact to through-penetration. The results of this program provide the key technology data required to assess the durability and damage-tolerance capability or advanced composites for use in commercial aircraft wing panel structure
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