Cylindrical Symmetry Discrimination of Magnetoelectric Optical Systematic Effects in a Pump-probe Atomic Parity Violation Experiment

A pump-probe atomic parity violation (APV) experiment performed in a longitudinal electric field, provides a signal breaking mirror symmetry while preserving the cylindrical symmetry of the set-up. The excited vapor acts on the probe beam as a linear dichroic amplifier, imprinting a very specific signature on the detected signal. Our differential polarimeter is oriented to yield a null result unless the excited atoms are endowed with a chirality of some kind. Ideally, only the APV (E-odd) and the calibration (E-even) signals contribute to a chiral atomic response, a situation highly favourable to the detection of a tiny effect. In the present work we give a thorough analysis of possible unwanted defects like stray transverse fields or misalignments which would spoil the ideal set-up and lead to chiral systematics. A possible way to suppress such effects is to perform global rotations of the experiment by incremental steps of 45 degrees, leaving both stray fields and misalignments unaltered. The conspiration of at least two defects is necessary to affect the E-odd polarimeter signal. The transverse nature of the defects manifests itself by an azimuthal cosine square modulation. The harmful systematics are those which survive the averaging over four successive configurations. They require the presence of a stray transverse electric field, which can be determined and eventually minimized by auxiliary measurements of the systematic effects, amplified by applying a known external magnetic field. Transverse stray magnetic fields must be compensated by a similar procedure. We also propose statistical correlation tests as diagnoses of the aforementioned systematic effects.Comment: Articl

In-Plane Loading of Brick Veneer over Wood Shear Walls

In the design of wood stud walls with brick veneer, current design building codes specify that the wood stud wall should resist all in-plane and out-of-plane loads (IBC 2009). For out-of-plane loads, this assumption is entirely justified as the brittle brick veneer will crack and lose its capacity to resist bending. For in-plane loads, the brick veneer is significantly stiffer than the wood shear wall, and the veneer is unlikely to crack before the wood shear wall reaches its allowable capacity. The assumption that the wood shear wall resists the entire load is based on the further assumption that the ties which connect the stud wall to the veneer will be sufficiently flexible to not transfer significant loads. Research has shown that this is not the case for typical US residential construction practices. The brick veneer can, in fact, resist significant in-plane loads

Pump-probe measurement of atomic parity violation in caesium with a precision of 2.6%

We present the atomic parity violation measurements made in Cs vapour using a pump-probe scheme. After pulsed excitation of the 6S-7S forbidden transition in the presence of a longitudinal electric field, a laser beam resonant with one of the 7S-6P transitions stimulates the 7S atom emission for a duration of 20 ns. The polarisation of the amplified probe beam is analysed. A seven-fold signature allows discrimination of the parity violating linear dichroism, and real-time calibration by a similar, known, parity conserving linear dichroism. The zero-field linear dichroism signal due to the magnetic dipole transition moment is observed for the first time, and used for in-situ determination of the electric field. The result, ImE1^{pv}= (-808+/- 21) 10^{-14} ea\_{0}, is in perfect agreement with the corresponding, more precise measurement obtained by the Boulder group. A transverse field configuration with large probe amplification could bring atomic parity violation measurements to the 0.1% accuracy level.Comment: "conference PAVI 06, Milos, Greece, May 2006

In-Plane Loading of Brick Veneer over Wood Shear Walls

In the design of wood stud walls with brick veneer, current design building codes specify that the wood stud wall should resist all in-plane and out-of-plane loads (IBC 2009). For out-of-plane loads, this assumption is entirely justified as the brittle brick veneer will crack and lose its capacity to resist bending. For in-plane loads, the brick veneer is significantly stiffer than the wood shear wall, and the veneer is unlikely to crack before the wood shear wall reaches its allowable capacity. The assumption that the wood shear wall resists the entire load is based on the further assumption that the ties which connect the stud wall to the veneer will be sufficiently flexible to not transfer significant loads. Research has shown that this is not the case for typical US residential construction practices. The brick veneer can, in fact, resist significant in-plane loads

Demonstration of an optical polarization magnifier with low birefringence

In any polarimetric measurement technique, enhancing the laser polarization change of a laser beam before it reaches the analyzer can help in improving the sensitivity. This can be performed using an optical component having a large linear dichroism, the enhancement factor being equal to the square root of the ratio of the two transmission factors. A pile of parallel plates at Brewster incidence looks appropriate for realizing such a polarization magnifier. In this paper, we address the problem raised by the interference in the plates and between the plates, which affects the measurement by giving rise to birefringence. We demonstrate that wedged plates provide a convenient and efficient way to avoid this interference. We have implemented and characterized devices with 4 and 6 wedged plates at Brewster incidence which have led to a decisive improvement of the signal to noise ratio in our ongoing Parity Violation measurement.Comment: 08 october 200

Evaluation of the ASK (Asking Saves Kids) Campaign in Two Midwestern Cities

We implemented a year-long community-based campaign to encourage parents to ask about firearms in homes that their children visit, in a small Midwestern city. Along with community residents and local leaders, we disseminated campaign messages through multiple communication channels. To assess message recall, attitudes, and whether parents asked about firearms, we conducted pre- and posttest surveys with randomly sampled adults in the intervention city and in a neighboring city. The posttest survey showed that parents in the intervention city were concerned about the danger of firearms when their child visits a friend's home, suggesting that the campaign influenced their attitudes

Can a microscopic stochastic model explain the emergence of pain cycles in patients?

A stochastic model is here introduced to investigate the molecular mechanisms which trigger the perception of pain. The action of analgesic drug compounds is discussed in a dynamical context, where the competition with inactive species is explicitly accounted for. Finite size effects inevitably perturb the mean-field dynamics: Oscillations in the amount of bound receptors spontaneously manifest, driven by the noise which is intrinsic to the system under scrutiny. These effects are investigated both numerically, via stochastic simulations and analytically, through a large-size expansion. The claim that our findings could provide a consistent interpretative framework to explain the emergence of cyclic behaviors in response to analgesic treatments, is substantiated.Comment: J. Stat. Mech. (Proceedings UPON2008

Editorial : environmental governance of urban and regional development – scales and sectors, conflict and cooperation

Recent years have continued to see a concern for the detrimental environmental impacts of human economic activities particularly in the form of enhanced global warming, sea level rise, land degradation and deforestation. Although it can be argued that economic development and growth remain the priority for governments at a variety of spatial scales or levels, these same governments also express a desire through a growing number of policy initiatives to make such development more sustainable and environmentally-friendly. A growing interest amongst policy makers has been in identifying the ways in which environmental protection measures can be made complementary to economic development aims. Rather than seeing the environment and the economy in opposition, there has been a focus on the growth potential from developing a green or low-carbon economy (OECD, 2011). At the urban and regional scale governments have increasingly begun to try and position themselves as destinations for new forms of green economy investments as a source of a new round of capital accumulation (GIBBS and O’NEILL, 2014). In total then, questions around the environment, climate change and sustainability look set to grow in importance for decision makers in cities and regions

An Alkali-Vapor Cell with Metal Coated Windows for Efficient Application of an Electric Field

We describe the implementation of a cylindrical T-shaped alkali-vapor cell for laser spectroscopy in the presence of a longitudinal electric field. The two windows are used as two electrodes of the high-voltage assembly, which is made possible by a metallic coating which entirely covers the inner and outer sides of the windows except for a central area to let the laser beams in and out of the cell. This allows very efficient application of the electric field, up to 2 kV/cm in a rather dense superheated vapor, even when significant photoemission takes place at the windows during pulsed laser irradiation. The body of the cell is made of sapphire or alumina ceramic to prevent large currents resulting from surface conduction observed in cesiated glass cells. The technique used to attach the monocrystalline sapphire windows to the cell body causes minimal stress birefringence in the windows. In addition, reflection losses at the windows can be made very small. The vapor cell operates with no buffer gas and has no magnetic part. The use of this kind of cell has resulted in an improvement of the signal-to-noise ratio in the measurement of Parity Violation in cesium vapor underway at ENS, Paris. The technique can be applied to other situations where a brazed assembly would give rise to unacceptably large birefringence in the windows