4,140 research outputs found
Chip breaking studies I : design and performance of ground chip breakers
"February 22, 1955."Balanced design will fit the chip breaker to the job, from American Machinist (April 26, 1954, pp. 117-124, Special Report: No. 360) -- How to select chip breakers I, II, III, from American Machinist (May 10, 1954, pp. 179, 181, 183, Reference Book Sheets) -- Chip breaking--a study of three-dimensional chip flow, from paper No. 53-5-9, presented at the ASME Spring Meeting, Columbus, Ohio (April 28-30, 1953) -- Economical chip breakers for machining steel, from Technical Aids for Small Business (May 1954, pp. 1-8)
Synchrotron brightness distribution of turbulent radio jets
Radio jets are considered as turbulent mixing regions and it is proposed that the essential small scale viscous dissipation in these jets is by emission of MHD waves and by their subsequent strong damping due, at least partly, to gyro-resonant acceleration of supra-thermal particles. A formula relating the synchrotron surface brightness of a radio jet to the turbulent power input is deduced from physical postulates, and is tested against the data for NGC315 and 3C31 (NGC383). The predicted brightness depends essentially on the collimation behavior of the jet, and, to a lesser extent, on the CH picture of a 'high' nozzle with accelerating flow. The conditions for forming a large scale jet at a high nozzle from a much smaller scale jet are discussed. The effect of entrainment on the prediction is discussed with the use of similarity solutions. Although entrainment is inevitably associated with the turbulent jet, it may or may not be a dominant factor depending on the ambient density profile
RXTE Hard X-ray Observation of A754: Constraining the Hottest Temperature Component and the Intracluster Magnetic Field
Abell 754, a cluster undergoing merging, was observed in hard X-rays with the
Rossi X-ray Timing Explorer (RXTE) in order to constrain its hottest
temperature component and search for evidence of nonthermal emission.
Simultaneous modeling of RXTE data and those taken with previous missions
yields an average intracluster temperature of keV in the 1-50 keV
energy band. A multi-temperature component model derived from numerical
simulations of the evolution of a cluster undergoing a merger produces similar
quality of fit, indicating that the emission measure from the very hot gas
component is sufficiently small that it renders the two models
indistinguishable. No significant nonthermal emission was detected. However,
our observations set an upper limit of
(90% confidence limit) to the nonthermal emission flux at 20 keV. Combining
this result with the radio synchrotron emission flux we find a lower limit of
0.2 G for the intracluster magnetic field. We discuss the implications of
our results for the theories of magnetic field amplifications in cluster
mergers.Comment: Accepted for Publication in the Astrophysical Journal, 22 pages, 5
figure
Expression and prognostic significance of Bcl-2 in ovarian tumours.
The expression of bcl-2 was studied in normal ovaries and in ovarian tumours by immunohistochemical analysis. Normal epithelium was strongly stained in all nine examined ovaries. In comparison, all tumour groups showed a substantially decreased tumour cell expression of the same order of magnitude. Thus, benign tumour cells were weakly stained in two and unstained in two samples, while the remaining eight showed strong expression. Of ten borderline samples, one was unstained and five had weakly and four strongly bcl-2 positive tumour cells. Finally, 24 of 50 malignant tumours showed strong staining, while weak or no expression in tumour cells was found in 16 and 10 samples respectively. The reduced staining deviated significantly from normal ovary for both borderline (P = 0.02) and malignant groups (P = 0.01). Tumour cell staining with the bcl-2 antibody was significantly reduced when tumour mass had to be left behind compared with those with no visible remaining tumour (P = 0.03 and 0.003 for weakly and strongly stained tumours respectively). The expression of bcl-2 in malignant tumour cells was inversely correlated with the expression of p53. Bcl-2 expression was correlated with survival with significantly reduced survival in weakly (P = 0.02) and unstained (P < 0.001) groups compared with those patients having strongly stained malignant tumour cells. This correlation between the presence of bcl-2 and survival was maintained in the subgroups of patients with advanced disease or with residual tumour bulk and was also the case in patients having p53-positive tumours. Our results indicate an inhibitory role of bcl-2 in development and progression of ovarian tumours
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