Time scales in atmospheric chemistry: coupled perturbations to N2O, NOy, and O3

Nitrous oxide (N2O) is one of the top three greenhouse gases whose emissions may be brought under control through the Framework Convention on Climate Change. Current understanding of its global budget, including the balance of natural and anthropogenic sources, is largely based on the atmospheric losses calculated with chemical models. A representative one-dimensional model used here describes the photochemical coupling between N2O and stratospheric ozone (O3), which can easily be decomposed into its natural modes. The primary, longest lived mode describes most of the atmospheric perturbation due to anthropogenic N2O sources, and this pattern may be observable. The photolytic link between O3 and N2O is identified as the mechanism causing this mode to decay 10 to 15 percent more rapidly than the N2O mean atmospheric lifetime, affecting the inference of anthropogenic sources.     

In situ measurements of organics, meteoritic material, mercury, and other elements in aerosols at 5 to 19 kilometers

In situ measurements of the chemical composition of individual aerosol particles at altitudes between 5 and 19 kilometers reveal that upper tropospheric aerosols often contained more organic material than sulfate. Although stratospheric aerosols primarily consisted of sulfuric acid and water, many also contained meteoritic material. Just above the tropopause, small amounts of mercury were found in over half of the aerosol particles that were analyzed. Overall, there was tremendous variety in aerosol composition. One measure of this diversity is that at least 45 elements were detected in aerosol particles. These results have wide implications for the complexity of aerosol sources and chemistry. They also offer possibilities for understanding the transport of atmospheric aerosols.     

Gold nanoelectrodes of varied size: transition to molecule-like charging

A transition from metal-like double-layer capacitive charging to redox-like charging was observed in electrochemical ensemble Coulomb staircase experiments on solutions of gold nanoparticles of varied core size. The monodisperse gold nanoparticles are stabilized by short-chain alkanethiolate monolayers and have 8 to 38 kilodaltons core mass (1.1 to 1.9 nanometers in diameter). Larger cores display Coulomb staircase responses consistent with double-layer charging of metal-electrolyte interfaces, whereas smaller core nanoparticles exhibit redox chemical character, including a large central gap. The change in behavior is consistent with new near-infrared spectroscopic data showing an emerging gap between the highest occupied and lowest unoccupied orbitals of 0.4 to 0.9 electron volt.     

The Solar Acoustic Spectrum and Eigenmode Parameters

The Global Oscillation Network Group (GONG) project estimates the frequencies, amplitudes, and linewidths of more than 250,000 acoustic resonances of the sun from data sets lasting 36 days. The frequency resolution of a single data set is 0.321 microhertz. For frequencies averaged over the azimuthal order m, the median formal error is 0.044 microhertz, and the associated median fractional error is 1.6 x 10(-5). For a 3-year data set, the fractional error is expected to be 3 x 10(-6). The GONG m-averaged frequency measurements differ from other helioseismic data sets by 0.03 to 0.08 microhertz. The differences arise from a combination of systematic errors, random errors, and possible changes in solar structure.     

Primary production of the biosphere: integrating terrestrial and oceanic components

Integrating conceptually similar models of the growth of marine and terrestrial primary producers yielded an estimated global net primary production (NPP) of 104.9 petagrams of carbon per year, with roughly equal contributions from land and oceans. Approaches based on satellite indices of absorbed solar radiation indicate marked heterogeneity in NPP for both land and oceans, reflecting the influence of physical and ecological processes. The spatial and temporal distributions of ocean NPP are consistent with primary limitation by light, nutrients, and temperature. On land, water limitation imposes additional constraints. On land and ocean, progressive changes in NPP can result in altered carbon storage, although contrasts in mechanisms of carbon storage and rates of organic matter turnover result in a range of relations between carbon storage and changes in NPP.     

Macrozamia toxicosis in a dog

A case of Macrozamia riedlei seed poisoning is described in a young Dachshund. Vomiting and depression commenced within 6 h of ingestion; other signs that developed included severe hepatopathy, jaundice, abdominal pain that was unresponsive to analgesics, severe gastro-intestinal haemorrhage and thrombocytopenia as well as crystalluria and marrow dyserythropoiesis. The dog was euthanased 6 days after ingestion of the seeds.     

Diagnostic ultrasound in veterinary practice: How safe is it?

This paper provides information on the safety of ultrasonic diagnostic procedures as currently used in veterinary practice. The known mechanisms of action are described and selected literature on biological effects of ultrasound is reviewed. Current international consensus is presented on the safety of medical ultrasound with respect to thermal effects. To date, there is no independently verified clinical evidence that the level of exposure delivered to the tissues during scanned grey-scale (‘B-mode’) imaging has any adverse effects. Lung haemorrhage has been observed in animal experiments using diagnostic exposures, but the effects have not been reported in the foetus. Equipment that uses pulsed Doppler transmits higher acoustic outputs in a stationary beam, and can produce temperature increases that may have significant biological consequences. When considering sonographic and pulsed Doppler examinations of the prenatal animal, the safety margins are small and the operator should be aware of the acoustic output of the equipment, the exposure time, and the sensitivity of target tissues.     

Use of clomipramine in the treatment of anxiety-related and obsessive-compulsive disorders in cats

Objective To evaluate the efficacy and tolerance of a treatment protocol for anxiety-related and obsessive-compulsive disorders in cats.
Design A study was undertaken to assess the clinical response in cats diagnosed with anxiety-related or obsessive-compulsive disorders to a treatment regimen that included clomipramine and behaviour modification.
Procedure The study group of 11 cats was acquired through referral. A detailed behavioural and clinical history was obtained. Presenting signs were urine spraying in seven cases, overgrooming in three and excessive vocalisation in one. Clomipramine was administered orally once daily. The mean starting dose was 0.4 mg/kg. If necessary, the dose was adjusted according to the clinical response of each cat. A behaviour modification program was designed and the owner instructed on its implementation. Cats were to continue on medication for at least 1 month after clinical signs disappeared, then medication withdrawal was to be attempted by decreasing the clomipramine dose progressively at weekly intervals while the behaviour modification program continued.
Results In all cases the presenting clinical sign was largely improved or disappeared. One cat was removed from the study by the owner. Four cats became lethargic at higher doses, but this resolved when the clomipramine dose was reduced. The average maintenance dosage was 0.3 mg/kg once daily. Clomipramine withdrawal was attempted in two cases: the behaviour returned in one case and the medication was reinstated at 0.3 mg/kg twice daily.
Conclusion Clomipramine was effective in controlling the signs of anxiety-related and obsessive-compulsive disorders in 10 of 10 assessable cases when used in combination with behaviour modification. Clomipramine was well tolerated.     

Treatment and control by vaccination of erysipelas in farmed emus (Dromaius novo-hollandiae)

Objective To study erysipelas in farmed emus and the treatment and control of the disease by vaccination.
Design A retrospective study of field outbreaks in emus and challenge experiments in mice using field and vaccine strains of the organism.
Procedure Outbreaks of the disease were described. Field strains of the organism were identified and tested by challenge experiments in mice against commercial vaccine strains.
Results Erysipelas was characterised by sudden death in yearling emus. Deaths mainly occurred during the cold wet months. Mortalities of 6 to 10% were seen within the first 7 to 10 days of an outbreak. Clinical signs were uncommon but some birds exhibited lethargy and greenish diarrhoea. Necropsy findings included marked petechial haemorrhages on the serosal surface of the large intestine in particular, pericardial effusion and congestion and mottling of the liver. Treatment consisted of individual or mass medication with procaine penicillin, reduction of stress factors such as overcrowding, and spelling and rotation of paddocks. Isolates from two field outbreaks were identified as strain 21. Complete protection was provided by a commercial strain 2b vaccine against challenge by strain 21 field isolates in mice. Annual vaccination of birds at 4 weeks and again at 8 weeks of age appeared to control further outbreaks on farms where the disease had previously occurred and vaccination appeared to protect for at least 12 months.
Conclusion Treatment of birds with antibiotics may be feasible in the face of an outbreak. However, annual vaccination of birds with an appropriate vaccine is recommended.