High Angular Resolution Stellar Imaging with Occultations from the Cassini Spacecraft II: Kronocyclic Tomography

We present an advance in the use of Cassini observations of stellar occultations by the rings of Saturn for stellar studies. Stewart et al. (2013) demonstrated the potential use of such observations for measuring stellar angular diameters. Here, we use these same observations, and tomographic imaging reconstruction techniques, to produce two dimensional images of complex stellar systems. We detail the determination of the basic observational reference frame. A technique for recovering model-independent brightness profiles for data from each occulting edge is discussed, along with the tomographic combination of these profiles to build an image of the source star. Finally we demonstrate the technique with recovered images of the {\alpha} Centauri binary system and the circumstellar environment of the evolved late-type giant star, Mira.Comment: 8 pages, 8 figures, Accepted by MNRA

Do Higher Cigarette Prices Encourage Youth to Use Marijuana?

Every major national tobacco legislation proposed in the past two years has called for significant increases in the price of cigarettes as a way to discourage youths from smoking. One argument used to oppose these bills is that increases in the price of cigarettes would cause youths to substitute marijuana for cigarettes. Although it has long been believed that cigarettes are a gateway drug,' no economic research has been done to determine whether cigarettes and marijuana are economic complements or substitutes. This paper begins to fill the void in the current research by examining the contemporaneous relationship between the demands for cigarettes and marijuana among a nationally representative sample of 8th, 10th and 12th graders from the 1992-1994 Monitoring the Future Project. Two part models are used to estimate reduced form demand equations. Examination of the cross-price effects clearly shows that higher cigarette prices will not increase marijuana use among youths. In addition to reducing youth smoking, we find that higher cigarette prices significantly reduce the average level of marijuana used by current users. Cigarette prices also have a negative effect on the probability of using marijuana findings are not significant at conventional levels.

Zebrafish Cytosolic Carboxypeptidases 1 and 5 Are Essential for Embryonic Development

The cytosolic carboxypeptidases (CCPs) are a subfamily of metalloenzymes within the larger M14 family of carboxypeptidases that have been implicated in the post-translational modification of tubulin. It has been suggested that at least four of the six mammalian CCPs function as tubulin deglutamylases. However, it is not yet clear whether these enzymes play redundant or unique roles within the cell. To address this question, genes encoding CCPs were identified in the zebrafish genome. Analysis by quantitative polymerase chain reaction indicated that CCP1, CCP2, CCP5, and CCP6 mRNAs were detectable between 2 h and 8 days postfertilization with highest levels 5–8 days postfertilization. CCP1, CCP2, and CCP5 mRNAs were predominantly expressed in tissues such as the brain, olfactory placodes, and pronephric ducts. Morpholino oligonucleotide-mediated knockdown of CCP1 and CCP5 mRNA resulted in a common phenotype including ventral body curvature and hydrocephalus. Confocal microscopy of morphant zebrafish revealed olfactory placodes with defective morphology as well as pronephric ducts with increased polyglutamylation. These data suggest that CCP1 and CCP5 play important roles in developmental processes, particularly the development and functioning of cilia. The robust and similar defects upon knockdown suggest that each CCP may have a function in microtubule modification and ciliary function and that other CCPs are not able to compensate for the loss of one

Racemases and epimerases operating through a 1,1-proton transfer mechanism:Reactivity, mechanism and inhibition

Racemases and epimerases catalyse changes in the stereochemical configurations of chiral centres and are of interest as model enzymes and as biotechnological tools. They also occupy pivotal positions within metabolic pathways and, hence, many of them are important drug targets. This review summarises the catalytic mechanisms of PLP-dependent, enolase family and cofactor-independent racemases and epimerases operating by a deprotonation/reprotonation (1,1-proton transfer) mechanism and methods for measuring their catalytic activity. Strategies for inhibiting these enzymes are reviewed, as are specific examples of inhibitors. Rational design of inhibitors based on substrates has been extensively explored but there is considerable scope for development of transition-state mimics and covalent inhibitors and for the identification of inhibitors by high-throughput, fragment and virtual screening approaches. The increasing availability of enzyme structures obtained using X-ray crystallography will facilitate development of inhibitors by rational design and fragment screening, whilst protein models will facilitate development of transition-state mimics

Pseudogout Associated Hip Pain in a Patient with HIV Infection

HIV infection is a global pandemic, currently affecting approximately 77,000 people in the UK and 33 million people around the world. The infection has widespread effects on the body and can involve the musculoskeletal system. It is therefore important that orthopaedic surgeons are aware of the condition and its sequelae. We present the case of a 46-year-old man with a 10-year history of HIV who presented with acute hip pain, difficulty weight-bearing, and constitutional symptoms. Following radiological, microbiological, and serological tests a diagnosis of pseudogout was established following microscopic analysis of the hip joint aspirate. The patient's symptoms resolved completely following the joint aspiration and NSAID therapy. Studies have shown a relationship between HIV infection and gout. The virus has also been linked to osteonecrosis, osteopenia, bone and joint tuberculosis, and septic arthritis from rare pathogens. However, it is difficult to fully ascertain whether these conditions are related to the HIV infection itself or the HAART (highly active antiretroviral therapy). There are no previously reported cases of HIV-infected patients with pseudogout. The case is discussed with reference to the literature

Environmental Quality Management in a Region with External Development Pressures

The objective of this study was to examine the problems of managing residuals and environmental quality in a region facing potentially rapid growth as a consequence of externally made development decisions. The research adapted and applied the residuals environmental management concept which recognizes the need for an integration of physical methods, implementation incentives and institutional arrangements in controlling air, water and solid residuals. The area selected for study, the Uintah Basin in Southeastern utah, has the potential for extensive energy resource and mineral development and could experience a large population influx and accelerated economic growth as a result. in the face of a wide range of possible resource developments, the study used an alternative futures approach, in which combinations of exogenous events leading to different types and levels of economic activities and employment inpacts were identified. Economic and land use simulation models were applied to project the effects of the futures on the basin. Materials balances were then drawn up for major polluting activities to determine the residuals that would be produced and discharged to the environment if there were not controls. An environmental impact and management model, structured as al inear programming model, was used to evaluate environmental management strategies. The model incorporated various production processes and residuals treatment methods. Air and water quality simulation models were applied to assess environmental impacts and generate model constraints. Several dimesnsions of environmental management strategies were analyzed including alternative production processes, waste treatment methods, and various implementation incentives such as effluent charges, effluent standards and effects of legal restructions. This report was submitted in fulfillment of Contract No. R-803203 by the Utah Water Research Laboratory, Utah State University under the sponsorship of the U.S. Environmental Protection Agency. This report covers the period July 22, 1974 to january 31, 1977, and was completed as of February 21, 1977