Inflation, Renormalization, and CMB Anisotropies

In single-field, slow-roll inflationary models, scalar and tensorial (Gaussian) perturbations are both characterized by a zero mean and a non-zero variance. In position space, the corresponding variance of those fields diverges in the ultraviolet. The requirement of a finite variance in position space forces its regularization via quantum field renormalization in an expanding universe. This has an important impact on the predicted scalar and tensorial power spectra for wavelengths that today are at observable scales. In particular, we find a non-trivial change in the consistency condition that relates the tensor-to-scalar ratio "r" to the spectral indices. For instance, an exact scale-invariant tensorial power spectrum, n_t=0, is now compatible with a non-zero ratio r= 0.12 +/- 0.06, which is forbidden by the standard prediction (r=-8n_t). Forthcoming observations of the influence of relic gravitational waves on the CMB will offer a non-trivial test of the new predictions.Comment: 4 pages, jpconf.cls, to appear in the Proceedings of Spanish Relativity Meeting 2009 (ERE 09), Bilbao (Spain

Evaluation of CBS 600 carburized steel as a gear material

Gear endurance tests were conducted with one lot of consumable-electrode vacuum-melted (CVM) AISI 9310 gears and one lot of air-melt CBS 600 gears. The gears were 8 pitch with a pitch diameter of 8.89 centimeters (3.5 in.). Bench-type rolling-element fatigue tests were also conducted with one lot of CVM AISI 9310, three lots of CVM CBS 600, and one of air-melt CBS 600 material. The rolling-element bars were 0.952 centimeter (0.375 in.) in diameter. The CBS 600 material exhibited pitting fatigue lives in both rolling-element specimens and gears at least equivalent to that of CVM AISI 9310. Tooth fracture failure occurred with the CBS 600 gears after overrunning a fatigue spall, but it did not occur with the CVM AISI 9310 gears. Tooth fracture in the CBS 600 was attributed to excessive carbon content in the case, excessive case depth, and a higher than normal core hardness

Astrometric jitter of the sun as a star

The daily variation of the solar photocenter over some 11 years is derived from the Mount Wilson data reprocessed by Ulrich et al. 2010 to closely match the surface distribution of solar irradiance. The standard deviations of astrometric jitter are 0.52 $\mu$AU and 0.39 $\mu$AU in the equatorial and the axial dimensions, respectively. The overall dispersion is strongly correlated with the solar cycle, reaching $0.91 \mu$AU at the maximum activity in 2000. The largest short-term deviations from the running average (up to 2.6 $\mu$AU) occur when a group of large spots happen to lie on one side with respect to the center of the disk. The amplitude spectrum of the photocenter variations never exceeds 0.033 $\mu$AU for the range of periods 0.6--1.4 yr, corresponding to the orbital periods of planets in the habitable zone. Astrometric detection of Earth-like planets around stars as quiet as the Sun is not affected by star spot noise, but the prospects for more active stars may be limited to giant planets.Comment: Accepted in Ap

Baryon asymmetry from hypermagnetic helicity in dilaton hypercharge electromagnetism

The generation of the baryon asymmetry of the Universe (BAU) from the hypermagnetic helicity, the physical interpretation of which is given in terms of hypermagnetic knots, is studied in inflationary cosmology, taking into account the breaking of the conformal invariance of hypercharge electromagnetic fields through both a coupling with the dilaton and that with a pseudoscalar field. It is shown that if the electroweak phase transition (EWPT) is strongly first order and the present amplitude of the generated magnetic fields on the horizon scale is sufficiently large, a baryon asymmetry with a sufficient magnitude to account for the observed baryon to entropy ratio can be generated.Comment: 16 pages, 2 figures, a reference added, typos correcte

Response of an atomic Bose-Einstein condensate to a rotating elliptical trap

We investigate numerically the response of an atomic Bose-Einstein condensate to a weakly-elliptical rotating trap over a large range of rotation frequencies. We analyse the quadrupolar shape oscillation excited by rotation, and discriminate between its stable and unstable regimes. In the latter case, where a vortex lattice forms, we compare with experimental observations and find good agreement. By examining the role of thermal atoms in the process, we infer that the process is temperature-independent, and show how terminating the rotation gives control over the number of vortices in the lattice. We also study the case of critical rotation at the trap frequency, and observe large centre-of-mass oscillations of the condensate.Comment: 14 pages, 8 figure

Solutions to security concerns about the radioactive legacy of the cold war that remains in urban areas

Until now, assessment of the Global Nuclear Legacy has mostly focused on nuclear weapon production sites, as they contain the absolute majority of volume and activity of accumulated radioactive waste. These wastes have received detailed examination after the end of the Cold War. The production sites were generally built in unpopulated areas due to secrecy requirements and most of them remain in lightly populated areas. However, some of these sites are now in urban environments due to the growth in population and the industry attracted by such facilities. Much of the Nuclear Legacy in what are now urban environments and densely populated areas was created by nuclear research, testing and educational centers between the 1940s- 1970s. Initially located in the suburbs of cities, they became a part of downtown as a result of growing urbanization. This legacy is less than 1% of the total amount of the nuclear legacy in countries with nuclear power plants. However, other factors, such as urban population density and proximity to operational or obsolete nuclear facilities, increase the importance of this legacy and even give priority in social considerations. Such nuclear facilities are not only a source of radioactive wastes that are often stored under inadequate conditions at the facility site, but also create dangerous targets as they have little or no protection against airplane crashes or missiles. This legacy has only recently received the attention of environmental and anti-terrorist specialists and the local population. Obviously, there is not only a need to prevent direct impact on the population living in the vicinity of the waste disposal site and spent nuclear fuel storage, but also a need for rehabilitation and utilization of this valuable land for governmental and commercial purposes. The countries sharing similar problems of a nuclear legacy in an urban environment could benefit from sharing their experience and cooperating in this field. As a step in this direction, the International Institute for Applied System Analysis (Laxenburg, Austria) convened an International Workshop on problems and experience gained at rehabilitation of radioactively contaminated sites in urban environments before and after natural or man initiated mishaps. The Workshop focused on how to remediate, how to ameliorate the consequences of security failures and in particular the problem of population growth around sensitive facilities. The purpose of the workshop is to look at security problems that have occurred in mega-cities. The workshop took place on the campus of Vanderbilt University during November 14-17, 2004

Toxicity of pyrolysis gases from wood

The toxicity of the pyrolysis gases from nine wood samples was investigated. The samples of hardwoods were aspen poplar, beech, yellow birch, and red oak. The samples of softwoods were western red cedar, Douglas fir, western hemlock, eastern white pine, and southern yellow pine. There was no significant difference between the wood samples under rising temperature conditions, which are intended to simulate a developing fire, or under fixed temperature conditions, which are intended to simulate a fully developed fire. This test method is used to determine whether a material is significantly more toxic than wood under the preflashover conditions of a developing fire