Superconducting helically wound magnet for the free-electron laser

Theoretical and experimental studies conducted by the Stanford Free Electron Laser group have resulted in the first operation of a free-electron laser amplifier and free-electron laser oscillator. Two superconducting helically wound periodic magnetics have been constructed for use with the laser. In this paper we present a discussion of design considerations and test results for the two magnets. The tests included measurement of the magnitude and the variation of the transverse magnetic field with radius in the bore of the magnets, the critical current, and the intensity, angular distribution, and spectrum of the spontaneous radiation emitted by electrons moving through the field.     

On "Psychology and mental retardation" position statement.

Comments on a statement that appeared in the March 1970 American Psychologist article entitled "Psychology and Mental Retardation" (Anonymous; see record 1970-15620-001). Part of the present commentary reads as follows: "I am not in agreement with the statement that educational psychological personnel are likely to provide the "most productive approaches" in dealing with the problems of mental retardation. This position simply places educational psychology in the same untenable bind that other disciplines, including medicine, psychiatry, education, and sociology, have achieved in the past when they claimed exclusive domain to serving the mentally retarded. Educational psychology should be devoting its efforts to working together with other disciplines rather than to making exaggerated claims of its superiority." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mixed finite element method for axisymmetric shells

A mixed variational formulation is used as basis for developing a mixed finite element method for axisymmetric shell. The independent unknowns of the method are the axial and radial displacement components, the rotation of the normal to the middle surface and the meridional bending stress couple. The basic element is a frustrum of curved meridian. General advantages of the mixed method are presented, one of which is the possibility of using piece-wise linear functions of the meridional arclength to represent the basic unknowns. Test results are presented for plate bending, transverse shear deformation, membrane behaviour, edge-zone bending, bending near the junction of two shells, convergence of the method and accuracy of middle surface curvature interpolation. Shell geometries considered are cylindrical, conical, spherical and ellipsoidal. Good results are obtained which should increase interest in the relatively less known and less tested mixed method as compared to the stiffness method.     

Effect of weightlifting upon left ventricular function and markers of cardiomyocyte damage

The purpose of this study was to assess left ventricular (LV) function and biochemical markers of myocyte after prolonged weightlifting activity. Seventeen male subjects (age range 20-34 years) performed a 90-min bout of weightlifting exercise consisting of three sets of 8-10 repetitions at 70% one-repetition maximum. Body mass, heart rate, systolic blood pressure (SBP) and echocardiographically determined indices of LV loading (LV internal diameter during diastole, LV meridonial wall stress), systolic function (stroke volume (SV), ejection fraction (EF), end-systolic pressure volume relationship; SBP/ESV) and diastolic filling (ratio of early to late; E:A) were obtained pre-exercise, immediately after and 24 h post-exercise. A 5-ml venous blood sample was obtained for the assessment of cardiac troponin T (cTnT) via third generation electrochemiluminescence assay. Data were assessed via one-way ANOVA and Pearson's correlation. Although SV declined (80.9 +/- 18.3 vs. 66.9 +/- 17.2, p < 0.05) there was no alteration in LV contractility (EF 62 +/- 6 vs. 59 +/- 7; SBP/ESV 3.51 +/- 1.4 vs. 3.51 +/- 1.4, p > 0.05). The E:A ratio was significantly decreased following exercise (1.78 +/- 0.41 vs. 1.33 +/- 0.37, p < 0.05). This decrease was not fully explained by loading conditions (r2 = 0.05 to 0.24). All values returned to baseline 24 h post-exercise. No cTnT was reported in any of the blood samples. In conclusion, there was no significant evidence of any LV contractile depression and no cTnT was observed post exercise. The small reduction in diastolic filling could not be explained by changes in haemodynamic loading or the post-exercise elevation in heart rate.     

Identification of structure by the common-sense approach

Mistakes are often made and perpetuated in the three-dimensional interpretation of single sections. Such errors can be avoided and corrected if the observer considers carefully what kind of three-dimensional shape has the greatest probability of yielding profiles such as are seen in the microscope; and if he does not take certain published or verbal statements at their face value.     

Determination of spatial distribution in two-phase flow using scattered gamma radiation

A procedure has been developed and tested for measurement of the phase distribution along a chord of the flow channel in steady state two-phase flow. The method involves measurement of the zeroth and first moments of the energy spectra of Compton scattered radiation. This information allows determination of the mean position and thickness of each condensed phase region along the interrogated chord in the flow channel. Preparation of empirical calibration curves employing perspex disks, rods or tubes is explained. An iterative procedure for correcting the calibration curves for self-absorption is developed. The procedure has enabled determination of the position and thickness to within a few percent in simulated steady state tests.     

Safety implications of stochastic analysis of nuclear reactor transients

A ‘neutron-temperature random process’ is formulated by means of a probability generating function technique. The model accounts for the effect of the negative temperature feedback by treating the temperature as a continuous random variable, thereby making possible the computation of the expected values of the temperature, neutron and cumulative fission densities as well as their standard deviations. The special relationship of the stochastic behavior of the nuclear reactor to safety considerations is discussed. Typical numerical results are presented related to startup accidents and Anticipated Transient Without Scram (ATWS) in thermal reactors.     

Chlamydia trachomatis during genital tract infection and in imminent abortion

Chlamydia trachomatis (Ch.t.) is suspected to be a dominant factor in the etiology of genito-urinary tract infectious diseases. The aim of the authors work was the evaluation of the Ch. t. presence in the cervix of women with adnexitis or with the imminent abortion. 300 women were investigated for the Ch.t. detection. The smear taken from the cervical canal was evaluated with 3 methods: direct immunofluorescence assay. Chlamydiazine test and culture. Ch.t. infection was detected in 27% of examined patients. The positive results was observed the more frequently in the patients showing the clinical symptoms of infection (42%) and in the pregnant women with imminent abortion symptoms (26%). The obtained results seem to confirm the pathogenic role of Ch.t. in the genital tract infectious diseases. Authors are postulating them the necessity of the prophylactic Ch.t. detection in the pregnant women.     

Nutritional Requirements and Diet Choices of the Pygmy Rabbit (Brachylagus idahoensis): A Sagebrush Specialist

Sagebrush (Artemisia tridentata) comprises up to 99% of the winter and 50% of the summer diets of pygmy rabbits (Brachylagus idahoensis). Few animals specialize on such plants as sagebrush, which contain high levels of plant chemicals that can be toxic. We investigated the nutritional requirements of pygmy rabbits and their ability and propensity to consume sagebrush alone and as part of a mixed diet. We compared diet choices of pygmy rabbits with that of a generalist forager, the eastern cottontail (Sylvilagus floridanus). Pygmy rabbits had a moderately low nitrogen requirement (306.5 mg N/kg^0.75/d), but a relatively high energy requirement, needing 750.8 kJ digestible energy/kg^0.75/d to maintain their body mass while residing in small cages. They digested fiber in pelleted diets similarly to other small hindgut fermenters, but both cottontails and pygmy rabbits digested the fiber in sagebrush better than expected based on its indigestible acid detergent lignin content. Pygmy rabbits consumed more sagebrush than cottontails, regardless of the amount and nutritional quality of supplemental pellets provided. When consuming sagebrush alone, they ate barely enough to meet their energy requirements, whereas cottontails ate only enough sagebrush to meet 67% of theirs. Both rabbit species ate more sagebrush as the quality and quantity of supplemental pellets declined, and more greenhouse-grown sagebrush than sagebrush grown outside. Urine was more acidic when consuming sagebrush than when consuming pellets, indicating detoxification by the liver. Pygmy rabbits do not require sagebrush to survive, but seem to tolerate terpenes and other plant chemicals in sagebrush better than cottontails do.