An X-Ray Method of Determining Rates of Diffusion in the Solid State

Gold and copper were simultaneously deposited in vacuum by vaporization on a plate of glass, the copper being deposited at a uniform rate while the gold was deposited in one hundred stratified layers in the copper by alternately raising and lowering the temperature of the molybdenum vaporizing trough containing the boiling gold. The translucent deposit so formed had a total thickness of about 10,000A and hence an average interplanar distance of 100A. In an especially constructed constructed x-ray spectrograph selective diffraction of Mo K radiation from these stratified films was observed corresponding to the artificially imposed periodicity of the stratification and the intensity of this diffracted image relative to the direct beam was found to fall off with time so as to indicate a "half-life" for the stratified structure of about two days. This suggests a general method for the study of average rates of diffusion and the determination of diffusion coefficients of solids in solids by utilizing the decay of such stratified films. Simple theoretical considerations should, through the action of diffusion alone, rapidly and automatically lose the higher Fourier harmonics of its periodic density distribution function and retain the fundamental in such a way as to render the determination of the diffusion coefficient quite accurate. The observed behavior of the diffracted maxima seem to support these expectations as does also the absence of any intensity in higher orders than the first. This purification by diffusion probably takes place principally during the depositing process itself while the temperatures are still quite high. Formulae are derived relating the observed rate of decay of the diffracted intensity, the artificial "grating coefficient" of the strata, and the diffusion coefficient. The method seems especially promising for substances and temperatures where diffusion is so slow as to be otherwise quite unobservable because the diffusion time varies as the square of the distance over which atoms must migrate and in this method these distances are so many orders of magnitude smaller than in any other

Oncologic And Orthopedic Rehabilitation For A Pancreatic Cancer Survivor Following Total Knee Arthroplasty Revision: A Case Report

An estimated 80% of cancer survivors undergoing chemotherapy or radiation to manage their cancer will experience cancer-related fatigue (CRF). The majority of cancer survivors are elderly – a population frequently affected by osteoarthritis (OA). Physical activity is the most recommended and evidence-based non-pharmacologic intervention for CRF. Strong evidence exists for lower-extremity resistance and functional exercise following Total Knee Arthroplasty (TKA). Evidence suggests utilization of targeted exercise prior to extensive abdominal surgery, such as a pancreaticoduodenectomy, improves post-operative functional outcomes. The purpose of this case report is to describe physical therapy management for total knee arthroplasty revision and Whipple procedure prehabilitation for a pancreatic cancer survivor on concurrent chemotherapy treatment with cancer-related fatigue.https://dune.une.edu/pt_studcrposter/1170/thumbnail.jp

The Thirty Kilowatt Continuous Input X‐Ray Equipment and High Constant Voltage Generating Plant of the Watters Memorial Research Laboratory at the California Institute of Technology

This report describes in detail with photographs and cross‐sectional views an x-ray tube with a gyrating water‐cooled target which the authors have operated continuously for periods of hours at 287,000 volts and 105 milliamperes. The theoretical predictions of DuMond, Watson and Hicks as to the ratio of safe load in moving and fixed targets seems to be roughly fulfilled by these results. The computed power output in the form of x-rays alone is some 3/4 kilowatt. The report further describes in detail the power supply equipment consisting of a synchronous motor driven 40 kw motor generator set giving 150 cycle current both half-waves of which, after transformation to high voltage, are rectified by two thermionic valves (filament emission 2 amperes maximum) of our own design and construction here fully described. The powerful electrical filter system to reduce the ripple to a low value and some technical problems arising from the large power rating of the equipment as well as the facilities now almost completed for stabilizing and measuring precisely the high voltage supplied to the x‐ray tube are discussed. At the outset a brief indication of the program of research work projected for this set is given

Decays of Ta182 and Ta183

The beta - decays of Ta182 and Ta183 into excited states of W182 and W183 have been studied using a curved crystal gamma-ray diffraction spectrometer and a homogeneous field, ring focusing beta-ray spectrometer. In each case de-excitation of the daughter nucleus gives rise to complex gamma-ray and conversion electron spectra. Energies and relative intensities of gamma rays and conversion lines arising from 27 transitions in W182 and 29 transitions in W183 are presented. Internal conversion coefficients and multipolarities have been deduced for most of the transitions and together with the gamma-ray energies form the basis of decay schemes proposed for both W182 and W183. The two decays are reported together because of the close experimental relationship which existed between them as a consequence of the method used for their production, namely, simultaneous production of Ta182 by single neutron capture and Ta183 by double neutron capture from stable Ta181. A corollary result is the value 1.3 x 10^4 barns for the thermal neutron cross section of Ta182. An interpretation of these results on W182 in terms of collective rotational motion has been given by A. Bohr and collaborators [Kgl. Danske Videnscab. Selskab, Mat.-fys. Medd. 29, No. 9 (1955)]

Measurement of High-Energy Gamma-Rays with a Photographic Bent Crystal Spectrograph

It has been shown by one of the authors and his coworkers that it is possible to determine accurately the wavelengths of gamma rays with quantum energies up to 1.3 Mev by direct crystal diffraction methods using the Mark I 2-meter bent crystal spectrograph at the California Institute of Technology. They were able to record and to measure with a precision of one part in 10^3 the two gamma rays at 1.17 and 1.33 Mev which are emitted by a Co^(60) source

An Examination of NBA MVP Voting Behavior: Does Race Matter?

The selection process of the most valuable player (MVP) in the National Basketball Association (NBA) was recently questioned as to whether African-American players were treated unfairly based on their race. Using NBA voting data from the 1995-2005 seasons, we develop two empirical models in order to examine the role that a player’s race plays in the determination of this award. Our estimates imply that after controlling for player, team, and market characteristics, there is no statistically significant effect of race on the likelihood that a player will appear on an MVP ballot or on the number of votes he will receive

Precision wave-length measurements of the 1.1- and 1.3-Mev lines of CO60 with the two-meter focusing curved-crystal spectrometer

Recent improvements in the two-meter focusing curved-crystal gamma-ray spectrometer are described which have extended its quantum energy range well above 1 Mev and have also yielded much better luminosity and resolving power than were obtained initially. The improved components are (1) the crystal holder whose aperture and resolving power have been nearly doubled and (2) the collimator the new model of which can now discriminate between the reflected and transmitted beams when these differ in direction by only 8 minutes of arc, a threefold improvement over our first model. Our plans for further possible improvements and the factors governing these are also discussed. Wavelengths of two gamma-rays emitted following β-decay of Co60 have been measured with this new equipment using a source of about 50 mc strength and found to have values of (9.308±0.005)×10-11 cm and (10.580±0.005)×10-11 cm corresponding to quantum energies of 1.3316±0.0010 Mev and 1.1715±0.0010 Mev, respectively. The lines appear to have equal intensities. The integrated reflection coefficient of the (310) planes of the curved-quartz crystal still appears to follow a λ2-dependence on wave-length down to 9 x.u. the shortest so far observed