On the Abundance of Holmium in the Sun

The abundance of holmium (Z = 67) in the Sun remains uncertain. The photospheric abundance, based on lines of Ho II, has been reported as +0.26 +/- 0.16 (on the usual scale where log(H) = 12.00), while the meteoretic value is +0.51 +/- 0.02. Cowan code calculations have been undertaken to improve the partition function for this ion by including important contributions from unobserved levels arising from the (4f^{11}6p + 4f^{10}(5d + 6s)^{2}) group. Based on 6994 computed energy levels, the partition function for Ho II is 67.41 for a temperature of 6000 K. This is approximately 1.5 times larger than the value derived from the 49 published levels. The new partition function alone leads to an increase in the solar abundance of Ho to log(Ho) = +0.43. This is within 0.08 dex of the meteoretic abundance. Support for this result has been obtained through LTE spectrum synthesis calculations of a previously unidentified weak line at 3416.38 A in the solar spectrum. Attributing the feature to Ho II, the observations may be fitted with log(Ho) = +0.53. This calculation assumes log(gf) = 0.25 and is uncertain by at least 0.1 dex.Comment: 16 pages, 4 figures, accepted for publication in Solar Physic

Comparison of SSM/I measurements to numerically-simulated cloud and precipitation during ERICA

These investigations focused essentially on the macroscale organization of cloud and precipitation which occurred during the 4th Intensive Observing Period (IOP-4) of the Experiment for Rapidly Intensifying Cyclones over the Atlantic (ERICA). This experiment, held off the East Coast of the United States and Canada during the winter of 1989, documented several episodes of rapid cyclonic storm development. Also playing a major role as validation and ground truth in these studies are Special Sensor Microwave Imager (SSM/I) retrievals of precipitable water, total liquid water and ice, generated by other Marshall Space Flight Center (MSFC) supported investigations. Model simulations produced to date suggest that, while the large-scale atmospheric dynamics was an essential driving mechanism, the role of condensation was crucial in facilitating the exceptionally rapid spinup of the cyclone and the low surface pressure. A model simulation of the precipitation rate at the time of most rapid storm intensification is shown in the accompanying figure. Heavier precipitation rates in the crescent shaped region are associated with deep convection along the leading edge of a dry intrusion behind the surface low. The majority of precipitation in the stratiform region to the northeast involved the production of ice with deposition from vapor to ice being the dominant process of growth. Some small amount of mixed phase cloudiness was present. Model condensate distributions matched well with SSM/I observations. The accompanying SSM/I imagery which delineates areas of large (greater than several hundred micron effective radius) precipitating ice over the ocean suggests that the model has done well in capturing the essential mechanisms responsible for the horizontal distribution of precipitation

EFFECT OF SPLENECTOMY ON THE SUSCEPTIBILITY OF MICE INOCULATED WITH DIPLOCOCCUS PNEUMONIAE

An experimental model is described which demonstrated increased susceptibility of mice to infection with D. pneumoniae following splenectomy. It was necessary to use small numbers of a particular strain of pneumococcus (D. pneumoniae type 6), intravenous infection and a particular strain of mouse (pathogen-free NCS strain). The increase in susceptibility persisted for at least 4 months after splenectomy. With modifications in experimental design such as use of large numbers of organisms, a different strain of pneumococcus, the intraperitoneal route of infection or a different mouse strain no increase or a much less impressive increase in susceptibility was demonstrated. Following intravenous injection of small numbers of D. pneumoniae Type 6 bacteremia tended to persist in all NCS mice. Multiplication of pneumococci subsequently occurred in a higher proportion of mice with splenectomy and at a more rapid rate than in control animals. Mice with splenectomy usually had more D. pneumoniae per ml of blood than per gram of any tissue. This suggested that in these mice multiplication of microorganisms occurs primarily in blood. In control mice higher concentrations of bacteria were present in spleen than in blood, and higher concentrations were found in blood than in other tissues. These results suggested that in normal mice infected intravenously with small numbers of D. pneumoniae Type 6, the spleen protects by removing and killing small but critical numbers of D. pneumoniae which are circulating in the blood. No evidence was found to suggest that the altered susceptibility is mediated by an effect of splenectomy on numbers of circulating leukocytes or on the antibacterial activity of mouse blood

A Note on Venture Capital Networks: Promise and Performance

Since 1984 Informal Venture Networks (VCNs) have been formed and are currently operating in several states and Canada. However, little has been written in regard to the performance of these networks. This article presents the results of preliminary research concerning their performance. Our research reveals several factors that are presently limiting the VCNs’ success and will continue to do so until diey are changed. The limited success of the VCNs to date is primarily the result of a lack of funding. Because of small operating budgets, most VCNs have only minimal amounts available for marketing and promotion. Until the VCNs are adequately funded, their high promise will not be matched by performance

Preliminary Development of Electrodes for an Electric-Arc Wind Tunnel

Two electrode configurations were tested in an electric-arc wind tunnel at the NASA Lewis Research Center. The results indicated approximately the same heat-loss rate per unit of arc power input for each of the configurations. Measured heat-loss rates were on the order of 40 percent of the arc power input. Nearly all this loss occurred at the anode. The power input and arc current limitations of the electrodes appear to be the critical design factors. Up to now, the maximum power to the stream has been 115 kilowatts with a cooled tungsten cathode and a cooled cylindrical anode incorporating a magnetic field. The maximum power input to this anode could not be established with the cooled tungsten cathode because cathode failures occurred at a gross power level of approximately 175 kilowatts. It was necessary to use a graphite cathode to seek the limitation of the anode. The results indicated that the anode limitation was primarily a function of arc current rather than power input. The anode was successfully operated at a power of 340 kilowatts at 1730 amperes; however, the anode failed with a power input of 324 kilowatts and a current of 2140 amperes. The magnetic flux density at the time of failure was 0.32 weber per square meter, or 3200 gauss. The graphite cathode was used only to establish the anode limitation; further investigation of graphite cathodes was discontinued because of the large amount of stream contamination associated with this type of electrode

Mandibular Fractures as Related to the Site of Trauma and the State of Dentition

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66573/2/10.1177_00220345610400062001.pd