Chemical and Dynamical Impacts of Stratospheric Sudden Warmings on Arctic Ozone Variability.

We use the Global Modeling Initiative (GMI) chemistry and transport model with Modern-Era Retrospective Analysis for Research and Applications (MERRA) meteorological fields to quantify heterogeneous chemical ozone loss in Arctic winters 2005-2015. Comparisons to Aura Microwave Limb Sounder N2O and O3 observations show the GMI simulation credibly represents the transport processes and net heterogeneous chemical loss necessary to simulate Arctic ozone. We find that the maximum seasonal ozone depletion varies linearly with the number of cold days and with wave driving (eddy heat flux) calculated from MERRA fields. We use this relationship and MERRA temperatures to estimate seasonal ozone loss from 1993-2004 when inorganic chlorine levels were in the same range as during the Aura period. Using these loss estimates and the observed March mean 63-90°N column O3, we quantify the sensitivity of the ozone dynamical resupply to wave driving, separating it from the sensitivity of ozone depletion to wave driving. The results show that about 2/3 of the deviation of the observed March Arctic O3 from an assumed climatological mean is due to variations in O3 resupply and 1/3 is due to depletion. Winters with a stratospheric sudden warming (SSW) before mid-February have about 1/3 the depletion of winters without one and export less depletion to the midlatitudes. However, a larger effect on the spring midlatitude ozone comes from dynamical differences between warm and cold Arctic winters, which can mask or add to the impact of exported depletion.

The global atmospheric environment for the next generation.

Air quality, ecosystem exposure to nitrogen deposition, and climate change are intimately coupled problems: we assess changes in the global atmospheric environment between 2000 and 2030 using 26 state-of-the-art global atmospheric chemistry models and three different emissions scenarios. The first (CLE) scenario reflects implementation of current air quality legislation around the world, while the second (MFR) represents a more optimistic case in which all currently feasible technologies are applied to achieve maximum emission reductions. We contrast these scenarios with the more pessimistic IPCC SRES A2 scenario. Ensemble simulations for the year 2000 are consistent among models and show a reasonable agreement with surface ozone, wet deposition, and NO2 satellite observations. Large parts of the world are currently exposed to high ozone concentrations and high deposition of nitrogen to ecosystems. By 2030, global surface ozone is calculated to increase globally by 1.5 +/- 1.2 ppb (CLE) and 4.3 +/- 2.2 ppb (A2), using the ensemble mean model results and associated +/-1 sigma standard deviations. Only the progressive MFR scenario will reduce ozone, by -2.3 +/- 1.1 ppb. Climate change is expected to modify surface ozone by -0.8 +/- 0.6 ppb, with larger decreases over sea than over land. Radiative forcing by ozone increases by 63 +/- 15 and 155 +/- 37 mW m(-2) for CLE and A2, respectively, and decreases by -45 +/- 15 mW m(-2) for MFR. We compute that at present 10.1% of the global natural terrestrial ecosystems are exposed to nitrogen deposition above a critical load of 1 g N m(-2) yr(-1). These percentages increase by 2030 to 15.8% (CLE), 10.5% (MFR), and 25% (A2). This study shows the importance of enforcing current worldwide air quality legislation and the major benefits of going further. Nonattainment of these air quality policy objectives, such as expressed by the SRES-A2 scenario, would further degrade the global atmospheric environment.

Inspirational recruitment and the Maryland Plan: overcoming the stigma of public psychiatry.

University-trained psychiatrists frequently avoid public-sector employment because they do not wish to be associated with stigmatized institutions. Inspirational recruitment--the elevation of poorly paid and unpleasant work to a noble cause--is one way of temporarily destigmatizing state psychiatry. The authors describe the impact of one such effort, the Maryland Plan, on recruitment of graduates of the University of Maryland psychiatric residency program into the state's psychiatric system. Significantly more graduates entered state psychiatry in the 15 years after the plan was implemented in 1978 (78 of 164 graduates, or 47.6 percent) than in the eight years before (seven of 57 graduates, or 12.3 percent). Data indicate that low salaries did not hurt recruitment, nor did doubling the stipends prevent the majority of recruits from leaving the public sector after a few years of service.

Chemical loss of ozone in the arctic polar vortex in the winter of 1991-1992.

In situ measurements of chlorine monoxide, bromine monoxide, and ozone are extrapolated globally, with the use of meteorological tracers, to infer the loss rates for ozone in the Arctic lower stratosphere during the Airborne Arctic Stratospheric Expedition II (AASE II) in the winter of 1991-1992. The analysis indicates removal of 15 to 20 percent of ambient ozone because of elevated concentrations of chlorine monoxide and bromine monoxide. Observations during AASE II define rates of removal of chlorine monoxide attributable to reaction with nitrogen dioxide (produced by photolysis of nitric acid) and to production of hydrochloric acid. Ozone loss ceased in March as concentrations of chlorine monoxide declined. Ozone losses could approach 50 percent if regeneration of nitrogen dioxide were inhibited by irreversible removal of nitrogen oxides (denitrification), as presently observed in the Antarctic, or without denitrification if inorganic chlorine concentrations were to double.

The effect of diet, exercise and 7,12-dimethylbenz(a)anthracene on food intake, body composition and carcass energy levels in virgin female BALB/c mice.

This study investigated the effect of diet, exercise and , 7,12-dimethylbenz(a)anthracene (DMBA), a mammary-tumor carcinogen, on food intake, energy consumption, body weight and body composition in virgin female BALB/c mice. Interactions were examined among three diet conditions (standard AIN-76A, restricted AIN-76A and high fat AIN-76A diet), two exercise conditions (with and without treadmill exercise) and two treatment conditions (carcinogen or corn oil sham). Mice were randomized to one of 12 groups at 6 wk of age; beginning at 8 wk of age, all mice received either 7,12-dimethylbenz(a)anthracene (1 mg/0.2 mL corn oil) or 0.2 mL of corn oil via gastric tube once each week for six consecutive weeks. Exercise in a rotating-drum treadmill was initiated at 10 wk of age and was increased to a final rate of 6 m/min for 60 min, 5 d/wk. Mice were killed at 24 wk of age, confirmed to be tumor-free and analyzed for protein and fat content, from which body energy was calculated. Energy consumption was highest in the standard diet-fed groups followed by the high fat diet-fed groups and the restricted diet-fed groups. The groups fed the standard diet and restricted diet had similar body weight and carcass energy. Exercise or DMBA treatment generally reduced food consumption, energy intake, body weight and carcass energy. In summary, diet, exercise and DMBA all had pronounced effects on energy consumption, which in turn affected body composition. These treatments may influence expression of breast cancer via their effects on body composition.

Reduced energy intake and moderate exercise reduce mammary tumor incidence in virgin female BALB/c mice treated with 7,12-dimethylbenz(a)anthracene.

This study evaluated the concurrent effects of diet (standard AIN-76A, restricted AIN-76A and high-fat diet) and moderate rotating-drum treadmill exercise on the incidence of 7,12-dimethylbenz(a)anthracene-induced mammary carcinomas in virgin female BALB/cMed mice free of murine mammary tumor virus. Exercise significantly reduced food consumption in the groups fed the standard diet and high fat diet. Although food consumption varied widely, final body weight was similar in all groups. Exercise had no effect on mammary tumor incidence in the standard diet-fed groups (without exercise, 47%; with exercise, 45%); however, exercise reduced mammary tumor incidence in the other groups as follows: restricted diet/no exercise, 28%; restricted diet/with exercise, 13%; high fat diet/no exercise, 31%; high fat diet/with exercise, 19%. Restricting food intake reduced mammary tumor incidence, but had no effect on body weight. Although energy intake was related to mammary tumor incidence, neither body weight nor dietary fat predicted tumor incidence.

Performance of lactating dairy cows fed tall fescue forage.

Two trials were conducted during consecutive summers to compare performance of lactating cows fed four varieties of tall fescue soilage. The first trial was conducted in 1983 and the second in 1984 using 25 midlactation Holsteins. Treatments included endophyte-free Kenhy; 8.1% endophyte-infected Johnstone (a prevarietal release); endophyte-free Kentucky 31; 63% endophyte-infected Kentucky 31; and orchardgrass or alfalfa as controls. In 1983, concentrate was fed twice each day at the rate of 4.1 kg per feeding, and in 1984, 4.5 kg were fed twice daily for first 4 wk and 4.1 kg per feeding thereafter. Intake of Kenhy was higher than all other tall fescue treatments when data for both trials were combined. Means of the high endophyte Kentucky 31 group were lower than all other treatments during both trials for milk yield, dry matter intake, body weight change, and serum prolactin in 1984 while higher for rectal temperature. Improved intake and performance of the cows consuming Kenhy compared with those consuming endophyte-free Kentucky 31 indicated the improved forage quality of this variety. Decreased performance of dairy cows consuming endophyte-infected tall fescue, even at a relatively low infection, was evident.

Effect of meptazinol on neuromuscular transmission in the isolated rat phrenic nerve-diaphragm preparation.

Meptazinol has been shown to have significant effects on neuromuscular transmission in the isolated rat phrenic nerve-diaphragm preparation. The response of the preparation to indirect electrical stimulation was increased in a concentration-dependent manner by meptazinol hydrochloride 2-32 micrograms ml-1. Meptazinol 0.5-2 micrograms ml-1 antagonized the effects the tubocurarine on this preparation, and in concentrations of 1 microgram ml-1 and greater, potentiated suxamethonium. These effects were similar to those obtained with neostigmine and it was demonstrated that meptazinol had significant anti-cholinesterase activity in the concentrations used. Inhibition of cholinesterase with ecothiopate revealed a neuromuscular blocking activity of meptazinol in concentrations as low as 0.25 micrograms ml-1.