Limits on the accuracy of isoelectronic gravity measurements at short separation due to patch potentials

In force sensing experiments intended to measure non-Newtonian gravitational signals electrostatic patch potentials can give rise to spurious forces, torques, and noise. Undesired patch-induced interactions can lead to systematic effects which limit accuracy, and noise can place lower limits on precision. In this paper we develop the theory for electrostatic patch effects on isoelectronic experiments, where their mean effect is nullified by design. We derive analytical expressions for the patch force and torque power spectrum to estimate the limitations introduced by patch-induced signals.Comment: 5 pages, 5 figure

Searching for galactic axions through magnetized media: QUAX status report

The current status of the QUAX R\&D program is presented. QUAX is a feasibility study for a detection of axion as dark matter based on the coupling to the electrons. The relevant signal is a magnetization change of a magnetic material placed inside a resonant microwave cavity and polarized with a static magnetic field.Comment: Contributed to the 13th Patras Workshop on Axions, WIMPs and WISPs, Thessaloniki, May 15 to 19, 201

Gas damping force noise on a macroscopic test body in an infinite gas reservoir

We present a simple analysis of the force noise associated with the mechanical damping of the motion of a test body surrounded by a large volume of rarefied gas. The calculation is performed considering the momentum imparted by inelastic collisions against the sides of a cubic test mass, and for other geometries for which the force noise could be an experimental limitation. In addition to arriving at an accurated estimate, by two alternative methods, we discuss the limits of the applicability of this analysis to realistic experimental configurations in which a test body is surrounded by residual gas inside an enclosure that is only slightly larger than the test body itself.Comment: 8 pages. updated with correct translational damping coefficient for cylinder on axis. added cylinder orthogonal to symmetry axis, force and torque. slightly edited throughou

Acceleration disturbances and requirements for ASTROD I

ASTRODynamical Space Test of Relativity using Optical Devices I (ASTROD I) mainly aims at testing relativistic gravity and measuring the solar-system parameters with high precision, by carrying out laser ranging between a spacecraft in a solar orbit and ground stations. In order to achieve these goals, the magnitude of the total acceleration disturbance of the proof mass has to be less than 10−13 m s−2 Hz−1/2 at 0.1 m Hz. In this paper, we give a preliminary overview of the sources and magnitude of acceleration disturbances that could arise in the ASTROD I proof mass. Based on the estimates of the acceleration disturbances and by assuming a simple controlloop model, we infer requirements for ASTROD I. Our estimates show that most of the requirements for ASTROD I can be relaxed in comparison with Laser Interferometer Space Antenna (LISA).Comment: 19 pages, two figures, accepted for publication by Class. Quantum Grav. (at press

Long range neutrino forces in the cosmic relic neutrino background

Neutrinos mediate long range forces among macroscopic bodies in vacuum. When the bodies are placed in the neutrino cosmic background, these forces are modified. Indeed, at distances long compared to the scale $T^{-1}$, the relic neutrinos completely screen off the 2-neutrino exchange force, whereas for small distances the interaction remains unaffected.Comment: 8 pages, 2 figure

An evidence-based treatment algorithm for colorectal polyp cancers:results from the Scottish Screen-detected Polyp Cancer Study (SSPoCS)

Objectives: Colorectal polyp cancers present clinicians with a treatment dilemma. Decisions regarding whether to offer segmental resection or endoscopic surveillance are often taken without reference to good quality evidence. The aim of this study was to develop a treatment algorithm for patients with screen-detected polyp cancers.Design: This national cohort study included all patients with a polyp cancer identified through the Scottish Bowel Screening Programme between 2000 and 2012. Multivariate regression analysis was used to assess the impact of clinical, endoscopic and pathological variables on the rate of adverse events (residual tumour in patients undergoing segmental resection or cancer-related death or disease recurrence in any patient). These data were used to develop a clinically relevant treatment algorithm.Results: 485 patients with polyp cancers were included. 186/485 (38%) underwent segmental resection and residual tumour was identified in 41/186 (22%). The only factor associated with an increased risk of residual tumour in the bowel wall was incomplete excision of the original polyp (OR 5.61, p=0.001), while only lymphovascular invasion was associated with an increased risk of lymph node metastases (OR 5.95, p=0.002). When patients undergoing segmental resection or endoscopic surveillance were considered together, the risk of adverse events was significantly higher in patients with incomplete excision (OR 10.23, p&lt;0.001) or lymphovascular invasion (OR 2.65, p=0.023).Conclusion: A policy of surveillance is adequate for the majority of patients with screen-detected colorectal polyp cancers. Consideration of segmental resection should be reserved for those with incomplete excision or evidence of lymphovascular invasion.</p

Observation of the thermal Casimir force

Quantum theory predicts the existence of the Casimir force between macroscopic bodies, due to the zero-point energy of electromagnetic field modes around them. This quantum fluctuation-induced force has been experimentally observed for metallic and semiconducting bodies, although the measurements to date have been unable to clearly settle the question of the correct low-frequency form of the dielectric constant dispersion (the Drude model or the plasma model) to be used for calculating the Casimir forces. At finite temperature a thermal Casimir force, due to thermal, rather than quantum, fluctuations of the electromagnetic field, has been theoretically predicted long ago. Here we report the experimental observation of the thermal Casimir force between two gold plates. We measured the attractive force between a flat and a spherical plate for separations between 0.7 $\mu$m and 7 $\mu$m. An electrostatic force caused by potential patches on the plates' surfaces is included in the analysis. The experimental results are in excellent agreement (reduced $\chi^2$ of 1.04) with the Casimir force calculated using the Drude model, including the T=300 K thermal force, which dominates over the quantum fluctuation-induced force at separations greater than 3 $\mu$m. The plasma model result is excluded in the measured separation range.Comment: 6 page

Efficiency of Pointing Dogs in Locating Northern Bobwhite Coveys

We studied the efficiency of pointing dogs in locating coveys of northern bobwhites (Colinus virginianus) using radiotelemetry from 1992-1997 on 2 private hunting plantations in southwest Georgia. During these 5 hunting seasons, 169 hunts generated data on 838 encounters with 254 separate radio-marked coveys. Pointing dogs located 53% of the available coveys, 25% of which were never seen by the hunters due to evasive behavior by the birds. An additional 12% of encountered coveys were seen by the hunters even though they were never located by the dogs. This resulted in the hunters seeing a total of just over half (53%) and shooting into approximately one-third (32%) of the total radio-marked coveys they encountered. An evaluation of false pointing was conducted by examining cases when dogs pointed radio-marked coveys that were never seen by the hunters. Most (58%) of these unproductive points were caused by coveys running away from pointing dogs, but were also attributed to wild flushes (28%) and pointed coveys that held tight and refused to flush (14%). The percentage of radio-marked coveys seen by hunters was highly variable from day-to-day (x = 53%, range = 0-100%), but fairly consistent between years (x = 53%, range = 40-63% ). Information obtained using pointing dogs appears to be more practical for measuring population trends than it is as a census technique

Survival of Northern Bobwhites on Areas With and Without Liberated Bobwhites

Increases in pen-raised quail releases are often implicated in the precipitous region-wide decline of wild northern bobwhites (Colinus virginianus). Therefore, we compared survival rates of wild radio-tagged northern bobwhites on a study area that received an influx of liberated pen-raised bobwhites from a neighboring property to those of wild bobwhites on a control area during 3 years in southwest Georgia. A total of 302 radio-tagged wild bobwhites were monitored on the wild-release (113) and wild-only areas (189) for a 22 week period from fall to spring each year during November 1993-April 1996. Fall-spring survival of wild bobwhites on the wild-only area (S = 0.43) was greater (P = 0.005) than that of wild bobwhites on the wild-release area (S = 0.18) for the 3 years combined. Losses to avian predation accounted for 38% and 58% of the fall population, respectively. Increased avian predation on the wildrelease area may have been attributed to avian predators attracted to the area