Coherence in macroscopic high harmonic generation for spatial focal phase distributions of monochromatic and broadband Gaussian laser pulses.

Efficient application of ultrafast laser sources from high harmonic generation requires an understanding of how the spectrum can be controlled - the extent of the highest harmonics and the strength and cleanness of the harmonic lines. We study one important aspect in the coherent build-up of macroscopic high-order harmonic generation, namely the impact of different phase distributions in the focal area on the features of the generated radiation. Specifically, we compare the high harmonic signals for the commonly-used Gouy distribution of a monochromatic beam with those for the phase distribution of a short broadband Gaussian pulse. To this end, we apply a theoretical model in which the microscopic yields are obtained via interpolation of results of the time-dependent Schrödinger equation, which are then used in an individual-emitter approach to determine the macroscopic signals. Regions of poor and good coherent build-up as a function of the position of the gas jet are identified using measures for the strength of the harmonic lines and for the impact of off-harmonic radiation. While the largest extent of the spectra as well as the strongest contribution of off-harmonic radiation is found for positioning the gas jet after the focus for both distributions, the relative strength of the harmonics is overall weaker for the short Gaussian pulse distribution and the spectra differ for a gas jet positioned at the focus. These differences are mainly caused by the additional dependence of the focal phase in the transverse direction for the short Gaussian pulse distribution.

Characterization of vacuum and deep ultraviolet pulses via two-photon autocorrelation signals.

Characterization of ultrashort vacuum and deep ultraviolet pulses is important in view of applications of those pulses for spectroscopic and dynamical imaging of atoms, molecules, and materials. We present an extension of the autocorrelation technique, applied for measurement of the pulse duration via a single Gaussian function. Analytic solutions for two-photon ionization of atoms by Gaussian pulses are used along with an expansion of the pulse to be characterized using multiple Gaussians at multi-color central frequencies. This approach allows one to use two-photon autocorrelation signals to characterize isolated ultrashort pulses and pulse trains, i.e., the time-dependent amplitude and phase variation of the electric field. The potential of the method is demonstrated using vacuum and deep ultraviolet pulses and pulse trains obtained from numerical simulations of macroscopic high harmonic spectra.

National athletic trainers' association position statement: fluid replacement for athletes.

OBJECTIVE: To present recommendations to optimize the fluid-replacement practices of athletes. BACKGROUND: Dehydration can compromise athletic performance and increase the risk of exertional heat injury. Athletes do not voluntarily drink sufficient water to prevent dehydration during physical activity. Drinking behavior can be modified by education, increasing accessibility, and optimizing palatability. However, excessive overdrinking should be avoided because it can also compromise physical performance and health. We provide practical recommendations regarding fluid replacement for athletes. RECOMMENDATIONS: Educate athletes regarding the risks of dehydration and overhydration on health and physical performance. Work with individual athletes to develop fluid-replacement practices that optimize hydration status before, during, and after competition.

Supragingival root surface removal during maintenance procedures utilizing an air-powder abrasive system or hand scaling. An in vitro study.

The purpose of this study was to determine the amount of root surface removal in vitro using an air-powder abrasive system or sharp curet on root surfaces simulating the cumulative effects of an every 3-month periodontal maintenance regimen over a 3-year period and to compare the amount of time spent in the utilization of each instrument. Fifty extracted teeth with fully formed roots were cleaned and mounted in one of 10 different artificial alveolar arches. Each arch contained one central incisor, one lateral incisor, one canine, one first and one second premolar. The buccal and mesial tooth root diameters were measured initially and after each treatment with a digital point micrometer. All teeth were stained with coffee and repositioned in their artificial alveolae and treated by the air-powder abrasive system or curet until all visible stain was removed. Time required for removal of stain in both treatment groups was recorded. Both groups were restained, retreated, and retimed 12 times to reproduce a 3-month maintenance interval for 3 years. The average root structure removed by the air-powder abrasive system following each treatment was 10.68 micron while the curet removed an average of 27.09 micron. Stain was removed 3.15 times faster by the air-powder abrasive system than with a curet.

Serum and salivary IgG and IgA response to initial preparation therapy.

The purpose of this study was to determine and compare IgG and IgA concentration in both serum and unstimulated whole saliva obtained prior to any therapy and following initial preparation therapy (IPT) in 15 healthy adult dentulous patients, five each of periodontal disease Classes I, II and III. During the first visit before therapy, 10 ml of whole blood and 5 ml of saliva were obtained. Serum protein electrophoresis was conducted to rule out immunoglobulinopathies. Radial cell immunodiffusion endpoint technique was employed on serum and saliva to determine IgG and IgA in mg/dl. Following IPT, achievement of plaque control and 3 weeks after any dental instrumentation, 10 ml of blood and 5 ml of saliva were obtained from each patient and IgG and IgA in mg/dl were determined. The following are trends that were observed: greater decrease in IgG and IgA in serum and saliva following IPT in Class I periodontal patients than in other classes; saliva was a better indicator of local humoral response than serum for this group of patients; the less severe the periodontal involvement, more consistent was the reduction in IgG and IgA following IPT, especially for saliva; IPT elicited a decreased IgG and IgA concentration when local antigenic stimuli were reduced by both patient and dentist.

Breast mycobacterial infection in a haemodialysis patient.

Mycobacterial infection is relatively common among patients maintained on haemodialysis and may present in uncommon locations and acquire an unusual course. We present a patient in whom a breast mass was found to be caused by primary mycobacterial infection. This is to our knowledge the first report on breast mycobacterial infection in a haemodialysis patient.

Society without labor: Some psychological issues in the cybernated society.

Social and psychological issues that may arise for those who will be working in a future cybernated society are discussed. An analysis of the psychological concomitants of the changes cybernation will effect in man's relationship with this work is attempted. Social sexual concomitants of shifting large sections of present day workers into human service occupations which are generally considered feminine are also considered. What is needed is a grand strategy of social change, a national plan involving every aspect of society which will take advantage of cybernation to construct a society without labor but which at the same time does not threaten present day laborers with exclusion from society.