Surface impregnation of wood : II. gaseous impregnation of wood : III. investigations on submarine decking : IV. investigation of marine adhesives.

This thesis presents results on methods used to produce a hard surfaced wood product. The methods involve the parting of the wood fibers on the surface by a special serrating tool, followed by surface impregnation and final curing. The serrations on the wood surface produce an artificial grain upon curing. A preliminary investigation was made to improve the rot-resistance of wood by gaseous treatment. Results of such treatments show some limited success with formaldehyde on yellow poplar and warrant further study. An investigation was made to find a substitute for teak wood used on submarine decking. A number of combinations of woods and impregnating agents were prepared and tested under simulated ocean conditions. The results of those tests indicate that a maple-mahogany laminate, when treated with the proper agent, will compare favorably with teak. The optimum curing conditions of several phenolic resin adhesives are presented as determined by an acetone extracting procedure. The results are presented for an attempt to replace the acetone extraction procedure by an x-ray diffraction method. X-ray diffraction patterns are presented of wood, -cellulose, and a phenolic adhesive. The viscosity characteristics of mixed Cascophen LT-67 phenolic adhesive are given. These viscosity correlations are based on the flow of material through an orifice

Pseudoresonance mechanism of all-optical frequency standard operation

We propose a novel approach to all-optical frequency standard design, based on a counterintuitive combination of the coherent population trapping effect and signal discrimination at the maximum of absorption for the probe radiation. The short-term stability of such a standard can achieve the level of 10^-14/(\tau)^1/2. The physics beyond this approach is dark resonance splitting caused by interaction of the nuclear magnetic moment with the external magnetic field.Comment: revtex4, references adde

High-contrast dark resonance on the D2 - line of 87Rb in a vapor cell with different directions of the pump - probe waves

We propose a novel method enabling to create a high-contrast dark resonance in the 87Rb vapor D2-line. The method is based on an optical pumping of atoms into the working states by a two-frequency, linearly-polarized laser radiation propagating perpendicularly to the probe field. This new scheme is compared to the traditional scheme involving the circularly-polarized probe beam only, and significant improvement of the dark resonance parameters is found. Qualitative considerations are confirmed by numerical calculations.Comment: 7 pages, 4 figure

Optical Clocks in Space

The performance of optical clocks has strongly progressed in recent years, and accuracies and instabilities of 1 part in 10^18 are expected in the near future. The operation of optical clocks in space provides new scientific and technological opportunities. In particular, an earth-orbiting satellite containing an ensemble of optical clocks would allow a precision measurement of the gravitational redshift, navigation with improved precision, mapping of the earth's gravitational potential by relativistic geodesy, and comparisons between ground clocks.Comment: Proc. III International Conference on Particle and Fundamental Physics in Space (SpacePart06), Beijing 19 - 21 April 2006, to appear in Nucl. Phys.

Distinctive physiological muscle synergy patterns define the Box and Block Task execution as revealed by electromyographic features

Stroke survivors experience muscular pattern alterations of the upper limb that decrease their ability to perform daily-living activities. The Box and Block test (BBT) is widely used to assess the unilateral manual dexterity. Although BBT provides insights into functional performance, it returns limited information about the mechanisms contributing to the impaired movement. This study aims at exploring the BBT by means of muscle synergies analysis during the execution of BBT in a sample of 12 healthy participants with their dominant and non-dominant upper limb. Results revealed that: (i) the BBT can be described by 1 or 2 synergies; the number of synergies (ii) does not differ between dominant and non-dominant sides and (iii) varies considering each phase of the task; (iv) the transfer phase requires more synergies. Clinical Relevance— This preliminary study characterizes muscular synergies during the BBT task in order to establish normative patterns that could assist in understanding the neuromuscular demands and support future evaluations of stroke deficit

Employment and Compliance with Pandemic Influenza Mitigation Recommendations

Noncompliance may result from job insecurity and financial problems associated with missing work

New miniaturized microwave cavity for Rubidium atomic clocks

Nowadays there is an increasing need for radically miniaturized and low-power atomic frequency standards, for use in mobile and battery-powered applications. For the miniaturization of double-resonance (DR) Rubidium (Rb-87) atomic clocks, the size reduction of the microwave cavity or resonator (MWR) to well below the wavelength of the atomic transition (6.835 GHz for Rb-87) has been a long-standing issue. Here we present a newly developed miniaturized MWR, the mu-LGR, consisting of a loop-gap resonator based cavity with very compact dimensions (volume < 0.9 cm(3)). The mu-LGR meets the requirements of the atomic clock application and its assembly can be performed using repeatable and low-cost techniques. The concept of the proposed device was validated through simulations and prototypes were successfully manufactured and tested. High-quality DR spectra and first clock stabilities were demonstrated experimentally, proving that the mu-LGR is suitable for integration in a miniaturized atomic clock