On the importance of testing gravity at distances less than 1cm

If the mechanism responsible for the smallness of the vacuum energy is consistent with local quantum field theory, general arguments suggest the existence of at least one unobserved scalar particle with Compton wavelength bounded from below by one tenth of a millimeter. We show that this bound is saturated if vacuum energy is a substantial component of the energy density of the universe. Therefore, the success of cosmological models with a significant vacuum energy component suggests the existence of new macroscopic forces with range in the sub-millimeter region. There are virtually no experimental constraints on the existence of quanta with this range of interaction.Comment: 9 pages TeX, 2 eps figures, uses mtexsis.tex and epsf.tex. Entry in 1996 Gravity Research Foundation essay competition. To be published in the Journal of General Relativity and Gravitatio

A Search for Scalar Chameleons with ADMX

Scalar fields with a "chameleon" property, in which the effective particle mass is a function of its local environment, are common to many theories beyond the standard model and could be responsible for dark energy. If these fields couple weakly to the photon, they could be detectable through the "afterglow" effect of photon-chameleon-photon transitions. The ADMX experiment was used in the first chameleon search with a microwave cavity to set a new limit on scalar chameleon-photon coupling excluding values between 2*10^9 and 5*10^14 for effective chameleon masses between 1.9510 and 1.9525 micro-eV.Comment: 4 pages, 3 figure

A SQUID-based microwave cavity search for dark-matter axions

Axions in the micro eV mass range are a plausible cold dark matter candidate and may be detected by their conversion into microwave photons in a resonant cavity immersed in a static magnetic field. The first result from such an axion search using a superconducting first-stage amplifier (SQUID) is reported. The SQUID amplifier, replacing a conventional GaAs field-effect transistor amplifier, successfully reached axion-photon coupling sensitivity in the band set by present axion models and sets the stage for a definitive axion search utilizing near quantum-limited SQUID amplifiers.Comment: 4 pages, 5 figures, submitted to PR

The Normal Structure of Regional Feline Gastric Mucosae: Scanning Electron Microscopic Study

Regions of cat\u27s stomach can be identified by looking at the surface epithelial cells by scanning electron microscopy (SEM). The luminal surface of cells of the cardiac region were elongated, of the fundus rounded, of the corpus polygonal shaped, and of the pyloric region diamond shaped. The quantity and distribution of microvilli covering the epithelial cells varies, being abundant and evenly distributed in the cardiac region and gradually decreasing in number toward the gastro-duodenal junction, where they were confined to cell perimeters. The colliculi varied in shape and distribution from few in the fundus and corpus to numerous in the pyloric region. Large numbers of gastric pits were present in the corpus. They diminish toward both the cardia and gastro-duodenal junction. The cardiac and pyloric glands were coiled. The gastric glands (glandula gastrica propria) were straight tubules in the fundus and coiled in the corpus. All luminal surfaces of glandular epithelial cells were covered with microvilli, but the regional distribution of microvilli on the cell was variable. Parietal, mucous neck, and chief (zymogen) cells were identified by their cytoplasmic structure. Parietal cells had long apical microvilli, mucous neck cells contained large numbers of globular mucous granules, and chief cells were vacuolated. A few G cells (Endocrinocytus gastrointestinalis) were seen in the cardiac region, large numbers in the pyloric region, and not found in fundus or corpus

Impact of Gulf Stream SST biases on the global atmospheric circulation

The UK Met Office Unified Model in the Global Coupled 2 (GC2) configuration has a warm bias of up to almost 7K in the Gulf Stream SSTs in the winter season, which is associated with surface heat flux biases and potentially related to biases in the atmospheric circulation. The role of this SST bias is examined with a focus on the tropospheric response by performing three sensitivity experiments. The SST biases are imposed on the atmosphere-only configuration of the model over a small and medium section of the Gulf Stream, and also the wider North Atlantic. Here we show that the dynamical response to this anomalous Gulf Stream heating (and associated shifting and changing SST gradients) is to enhance vertical motion in the transient eddies over the Gulf Stream, rather than balance the heating with a linear dynamical meridional wind or meridional eddy heat transport. Together with the imposed Gulf Stream heating bias, the response affects the troposphere not only locally but also in remote regions of the Northern Hemisphere via a planetary Rossby wave response. The sensitivity experiments partially reproduce some of the differences in the coupled configuration of the model relative to the atmosphere-only configuration and to the ERA-Interim reanalysis. These biases may have implications for the ability of the model to respond correctly to variability or changes in the Gulf Stream. Better global prediction therefore requires particular focus on reducing any large western boundary current SST biases in these regions of high ocean-atmosphere interaction

Stress, burnout, depression and work-satisfaction amongst UK anaesthetic trainees; a quantitative analysis of the Satisfaction and Wellbeing in Anaesthetic Training study

There is growing evidence that anaesthetic trainees experience, and may be particularly susceptible to, high levels of work stress, burnout and depression. This is a concern for the safety and wellbeing of these doctors and the patients they treat. To date, there has been no in-depth evaluation of these issues amongst UK anaesthetic trainees examining which groups may be most affected and the professional and personal factors which are associated. We conducted an anonymous electronic survey to determine the prevalence of perceived stress, risk of burnout and depression, and work-satisfaction among anaesthetic trainees within South West England and Wales and explored in detail the influence of key demographic, lifestyle and anaesthetic training variables. We identified a denominator of 619 eligible participants and received 397 responses; a response rate of 64%. We observed a high prevalence of perceived stress (37% [95% CI 32 – 42]), burnout risk (25% [21-29]) and depression risk (18% [15-23]) and found that these issues frequently co-exist. Having no children, >3 days of sickness absence in the previous year, 7.5hrs/week of additional non-clinical work were independently predictive of negative psychological outcomes. Although female gender was associated with higher stress, burnout risk was more likely in male respondents. This information could help in the identification of at-risk groups, as well as informing ways to support these groups and influence resource and intervention design. Targeted interventions, such as modification of exercise behaviour and methods of reducing stressors relating to non-clinical workloads, warrant further research

Acoustically driven storage of light in a quantum well

The strong piezoelectric fields accompanying a surface acoustic wave on a semiconductor quantum well structure are employed to dissociate optically generated excitons and efficiently trap the created electron hole pairs in the moving lateral potential superlattice of the sound wave. The resulting spatial separation of the photogenerated ambipolar charges leads to an increase of the radiative lifetime by orders of magnitude as compared to the unperturbed excitons. External and deliberate screening of the lateral piezoelectric fields triggers radiative recombination after very long storage times at a remote location on the sample.Comment: 4 PostScript figures included, Physical Review Letters, in pres

Constraints on Light Pseudoscalars Implied by Tests of the Gravitational Inverse-Square Law

The exchange of light pseudoscalars between fermions leads to a spin-independent potential in order g^4, where g is the Yukawa pseudoscalar-fermion coupling constant. This potential gives rise to detectable violations of both the weak equivalence principle (WEP) and the gravitational inverse-square law (ISL), even if g is quite small. We show that when previously derived WEP constraints are combined with those arisingfrom ISL tests, a direct experimental limit on the Yukawa coupling of light pseudoscalars to neutrons can be inferred for the first time (g_n^2/4pi < 1.6 \times 10^-7), along with a new (and significantly improved) limit on the coupling of light pseudoscalars to protons.Comment: 12 pages, Revtex, with 1 Postscript figure (submitted to Physical Review Letters

Move of a large but delicate apparatus on a trailer with air-ride suspension

When valuable delicate goods are shipped by truck, attention must be paid to vibrations that may cause damage. We present a case study of moving an extremely delicate 6230-kg superconducting magnet, immersed in liquid nitrogen, from Livermore, CA to Seattle, WA showing the steps of fatigue analysis of the load, a test move, and acceleration monitoring of the final move to ensure a successful damage-free transport