No abstract

The MACHO project carries out regular photometric monitoring of millions of stars in the Magellanic Clouds and Galactic Bulge, to search for very rare gravitational microlensing events due to compact objects in the galactic halo and disk. A preliminary analysis of one eld in the Galactic Bulge, containing 430; 000 stars observed for 190 days, reveals four stars which show clear evidence for brightenings which are time-symmetric, achromatic in our two passbands, and have shapes consistent with gravitational microlensing. This is signi cantly higher than the 1 event expected from microlensing by known stars in the disk. If all four events are due to microlensing, a 95% con dence lower limit on the optical depth towards our bulge eld is 1:3 10 6 , and a \best t" value is 1:6 10 6 = ,where is the detection e ciency of the experiment, and < 0:4. If the true optical depth is close to the \best t" value, possible explanations include a \maximal" disk which accounts for most of the galactic circular velocity at the solar radius, a halo which is centrally concentrated, or bulge-bulge microlensing.

Metronidazole is a synthetic antibacterial and antiprotozoan agent. Crystallization occurs in aqueous metronidazole benzoate suspensions caused by an anhydrate to monohydrate conversion. This study aimed to develop an aqueous metronidazole benzoate suspension that does not exhibit this hydration and the accompanying crystal growth. Four suspending agent systems were evaluated. Xanthan gum and Avicel RC-591 (a combination of microcrystalline cellulose and carboxymethylcellulose sodium) were found to be the suspending agents that resulted in optimal formulation properties. Monohydrate formation did not occur in product containing Avicel RC-591, indicating that suspending agents may exert a positive effect on metronidazole benzoate suspension stability.

We consider simultaneous optical data obtained during the recent X-ray turn-off of CAL 83. Combining the optical behaviour with the observed X-ray decay time, we show that a model of cessation of steady nuclear burning is viable if the white dwarf is massive. Our model provides a natural explanation for the subsequent return of the supersoft X-ray emission.

We have obtained radial velocities of three K giants and one faint carbon star in LGS 3, a dwarf companion of M31, based on 12 individual spectra obtained with the HIRES spectrograph on the Keck I telescope. The mean precision of these measurements is 3.8 km s~1. The mean systemic velocity of LGS 3 is [282.2 ^3.5 km s~1. Monte Carlo simulations that take into account the individual velocity uncertainties and the maximum observed velocity di †erence reveal that the central velocity dispersion of LGS 3 is in the range 2.6È30.5 km s~1, with 95% conÐdence ; the most likely value for the central dispersion is km s~1. These results agree with the kinematics of H I gas in LGS 3. This contrasts with the 7.9~2.9 `5.3 tendency for the gas and stars in other low-luminosity Local Group dwarfs to exhibit distinct spatial and kinematic properties. Taking into account the relative youth of LGS 3, we conclude that the "" asymptotic ÏÏ M/L ratioÈthe value the galaxy would exhibit if it were composed only of ancient starsÈis M/L V,LGS3º 11 (at a 97.5% conÐdence level), with a most probable value of These values are consistent with the 95 ~56 `175. ratios observed in other well-studied early-type dwarfs of the Local Group. We have also estimated M/L V the mass of LGS 3 using modiÐed Newtonian dynamics. These data represent the Ðrst moderately high precision optical spectra of giants in a dwarf system beyond the Galactic halo. We suggest future studies that are now feasible to study the dynamics of dwarf galaxies throughout the Local Group and beyond. INTRODUCTIONÈÈÈÈÈÈÈÈÈÈÈÈÈÈÈ 1 Based on observations obtained at the W. M. Keck Observatory, which is jointly operated by the California Institute of Technology and the University of California.