The rate of mass loss and variations in the wind from the Be star delta Centauri

Copernicus ultraviolet scans of the Be star delta Centauri obtained in 1976 and 1979, show a significant variation in the Si III lambda 1206 profile, The strong asymmetry that was present in 1976 had disappeared by 1979. The Si IV lambda 1400 doublet was also asymmetric in 1976, but was not observed in 1979. A quantitative fit of the line shapes to theoretical wind profiles shows that the mass-loss rate in 1976 was 2 x 10 to the minus 8th power/yr, and that the rate of mass loss in Si III was at least one order of magnitude less in 1979. It is not possible to determine whether the variation represented an overall change in the lass-loss rate, or whether it was due to a change in the ionization balance. The profile fitting procedure resulted in the adoption of assumed underlying photospheric Si III and Si IV profiles, and the equivalent widths measured from these profiles are most consistent with T sub eff between 30,000 and 35,000 K, somewhat hotter than implied by the spectral classification normally assigned to this star. The ultraviolet photospheric line widths, coupled wit published theoretical analyses of rotational gravitational darkening, imply an intrinsic equatorial velocity of about 310 km/sec and an angle of inclination of the rotational axis to the line of sight of i is less than or equal to 44 deg

Admission Diagnosis of Cerebral Malaria in Adults in an Endemic Area of Tanzania:Implications and Clinical Description

Cerebralmalariais commonly diagnosed in adults in endemic areas in Africa, both in hospitals and in the community. This presents a paradox inconsistent with the epidemiological understanding that the development of immunity during childhood confers protection against severe disease in adult life. To establish the contribution of Plasmodium falciparum infection in adults admitted with neurological dysfunction in an endemic area, to assess the implications of an admission clinical diagnosis of ‘cerebral malaria’ on the treatment and clinical outcome, and to describe the clinical features of patients with malaria parasitaemia. Prospective observational study. We studied adult patients admitted with neurological dysfunction to Muhimbili National Hospital, Dar-es-Salaam, Tanzania from October 2000 to July 2001. A full blood count was done and serum creatinine, blood glucose and P. falciparum parasite load were measured. Of 199 patients (median age 34.5 years), 38% were diagnosed as ‘cerebral malaria’ on admission, but only 7.5% had detectable parasitaemia, giving a positive predictive value of 13.3%. Only 1% fulfilled the WHO criteria for cerebral malaria. The prevalence of parasitaemia (7.5%) was less than that observed in a group of asymptomatic controls (9.3%), but distribution of parasite densities was higher in the patients. Mortality was higher in patients with no parasitaemia (22.3%) than in those with parasitaemia (13%). Cerebral malaria was grossly overdiagnosed, resulting in unnecessary treatment and insufficient investigation of other possible diagnoses, which could lead to higher mortality. Extension of this misperception to the assessment of cause of death in community surveys may lead to an overestimation of the impact of malaria in adults.\u

Charge-transfer Cross Sections For Negative Ions On Atomic And Molecular Targets

Charge-transfer cross sections for H- on O, O2, and NO2; O- on H, O, H2, O2, and NO2; and C- on H and O have been measured over an energy range of 0.5 to 4 keV using a modulated crossed-beam apparatus. The experimental cross sections are compared with theories of resonant and non-resonant charge transfer based on a two-state approximation. For the reactions H-+O O-+H, the cross sections are found to be consistent with detailed balancing. The effect of electron detachment on charge-transfer cross sections is discussed. © 1969 The American Physical Society

Observations of rotationally resolved C3 in translucent sight lines

The rotationally resolved spectrum of the A ^1Pi_u <- X ^1Sigma^+_g 000-000 transition of C3, centered at 4051.6A, has been observed along 10 translucent lines of sight. To interpret these spectra, a new method for the determination of column densities and analysis of excitation profiles involving the simulation and fitting of observed spectra has been developed. The populations of lower rotational levels (J<14) in C3 are best fit by thermal distributions that are consistent with the kinetic temperatures determined from the excitation profile of C2. Just as in the case of C2, higher rotational levels (J>14) of C3 show increased nonthermal population distributions in clouds which have been determined to have total gas densities below ~500 cm-3.Comment: 12 pages, 4 figures, accepted for publication in The Astrophysical Journa

Search for antiproton decay at the Fermilab Antiproton Accumulator

A search for antiproton decay has been made at the Fermilab Antiproton Accumulator. Limits are placed on thirteen antiproton decay modes. The results include the first explicit experimental limits on the muonic decay modes of the antiproton, and the first limits on the decay modes e- gamma gamma, and e- omega. The most stringent limit is for the decay mode pbar-> e- gamma. At 90% C.L. we find that tau/B(pbar-> e- gamma) > 7 x 10^5 yr. The most stringent limit for decay modes with a muon in the final state is for the decay pbar-> mu- gamma. At 90% C.L. we find that tau/B(pbar-> mu- gamma) > 5 x 10^4 yr.Comment: 20 pages, 8 figures. Submitted to Phys. Rev. D. Final results on 13 channels (was 15) are presente

CO and C_2 Absorption Toward W40 IRS 1a

The H II region W40 harbors a small group of young, hot stars behind roughly 9 magnitudes of visual extinction. We have detected gaseous carbon monoxide (CO) and diatomic carbon (C_2) in absorption toward the star W40 IRS 1a. The 2-0 R0, R1, and R2 lines of 12CO at 2.3 micron were measured using the CSHELL on the NASA IR Telescope Facility (with upper limits placed on R3, R4, and R5) yielding an N_CO of (1.1 +/- 0.2) x 10^18 cm^-2. Excitation analysis indicates T_kin > 7 K. The Phillips system of C_2 transitions near 8775 Ang. was measured using the Kitt Peak 4-m telescope and echelle spectrometer. Radiative pumping models indicate a total C_2 column density of (7.0 +/- 0.4) x 10^14 cm^-2, two excitation temperatures (39 and 126 K), and a total gas density of n ~ 250 cm^-3. The CO ice band at 4.7 micron was not detected, placing an upper limit on the CO depletion of delta < 1 %. We postulate that the sightline has multiple translucent components and is associated with the W40 molecular cloud. Our data for W40 IRS 1a, coupled with other sightlines, shows that the ratio of CO/C_2 increases from diffuse through translucent environs. Finally, we show that the hydrogen to dust ratio seems to remain constant from diffuse to dense environments, while the CO to dust ratio apparently does not.Comment: To appear in The Astrophysical Journal 17 pages total, 5 figures Also available at http://casa.colorado.edu/~shuping/research/w40/w40.htm