Hydrogen radicals, nitrogen radicals, and the production of O3 in the upper troposphere

The concentrations of the hydrogen radicals OH and HO2 in the middle and upper troposphere were measured simultaneously with those of NO, O3, CO, H2O, CH4, non-methane hydrocarbons, and with the ultraviolet and visible radiation field. The data allow a direct examination of the processes that produce O3 in this region of the atmosphere. Comparison of the measured concentrations of OH and HO2 with calculations based on their production from water vapor, ozone, and methane demonstrate that these sources are insufficient to explain the observed radical concentrations in the upper troposphere. The photolysis of carbonyl and peroxide compounds transported to this region from the lower troposphere may provide the source of HOx required to sustain the measured abundances of these radical species. The mechanism by which NO affects the production of O3 is also illustrated by the measurements. In the upper tropospheric air masses sampled, the production rate for ozone (determined from the measured concentrations of HO2 and NO) is calculated to be about 1 part per billion by volume each day. This production rate is faster than previously thought and implies that anthropogenic activities that add NO to the upper troposphere, such as biomass burning and aviation, will lead to production of more O3 than expected.     

Abrupt climate events 500,000 to 340,000 years ago: evidence from subpolar north atlantic sediments

Subpolar North Atlantic proxy records document millennial-scale climate variations 500,000 to 340,000 years ago. The cycles have an approximately constant pacing that is similar to that documented for the last glacial cycle. These findings suggest that such climate variations are inherent to the late Pleistocene, regardless of glacial state. Sea surface temperature during the warm peak of Marine Isotope Stage 11 (MIS 11) varied by 0.5 degrees to 1 degrees C, less than the 4 degrees to 4.5 degrees C estimated during times of ice growth and the 3 degrees C estimated for glacial maxima. Coherent deep ocean circulation changes were associated with glacial oscillations in sea surface temperature.     

Shipboard geophysical indications of asymmetry and melt production beneath the east pacific rise near the MELT experiment

Near the Mantle Electromagnetic and Tomography (MELT) Experiment, seamounts form and off-axis lava flows occur in a zone that extends farther to the west of the East Pacific Rise than to the east, indicating a broad, asymmetric region of melt production. More seamounts, slower subsidence, and less dense mantle on the western flank suggest transport of hotter mantle toward the axis from the west. Variations in axial ridge shape, axial magma chamber continuity, off-axis volcanism, and apparent mantle density indicate that upwelling is probably faster and more melt is produced beneath 17 degrees15'S than beneath 15 degrees55'S. Recent volcanism occurs above mantle with the lowest seismic velocities.     

Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission

The magnetometer and electron reflectometer investigation (MAG/ER) on the Mars Global Surveyor spacecraft has obtained magnetic field and plasma observations throughout the near-Mars environment, from beyond the influence of Mars to just above the surface (at an altitude of approximately 100 kilometers). The solar wind interaction with Mars is in many ways similar to that at Venus and at an active comet, that is, primarily an ionospheric-atmospheric interaction. No significant planetary magnetic field of global scale has been detected to date (<2 x 10(21) Gauss-cubic centimeter), but here the discovery of multiple magnetic anomalies of small spatial scale in the crust of Mars is reported.     

Growth response and fatty acid composition of juvenile red claw crayfish (Cherax quadricarinatus) fed different sources of dietary lipid

A study was conducted to determine the effects of different sources of dietary lipid that differ in fatty acid (FA) composition on growth, feed conversion ratio (FCR), survival, and whole‐body proximate and FA composition of juvenile red claw. Juvenile red claw (0.55 ± 0.02 g) were reared over a 12‐week period. Five practical diets were supplemented with 70 g kg^?1 oil (by weight) from either linseed oil (LO), canola oil (CAO), corn oil (CO), beef tallow (BT) or menhaden oil (MO) and formulated to contain 400 g kg^?1 crude protein. Red claw were fed three times daily (800, 1200 and 1600) to controlled excess. At the conclusion of the experimental period, there were no significant differences (P > 0.05) found in percentage survival and FCR among dietary treatments and values averaged 85.4% and 3.4, respectively. However, final mean weight and specific growth rate of red claw fed Diet 1 (LO) was significantly higher (16.44 g and 3.95% day^?1, respectively) compared with that of red claw fed Diet 4 (BT; 12.24 g and 3.43% day^?1, respectively), but not different from red claw fed the other three diets. Likewise, red claw fed Diets 1 (LO) and 2 (CAO) had significantly higher percentage weight gain (2990 and 2880%, respectively) compared with the BT diet (2124%), but not different from red claw fed Diets 3 (CO) and 5 (MO). Whole‐body fat and ash composition was significantly affected (P < 0.05) by source of added lipid, but no differences were found in whole‐body moisture and protein. Moreover, whole‐body FA composition showed differences among the varying oil sources and primarily reflected the FA in the diets. Results of the present study indicate that plant oils LO, CAO and CO rich in linolenic acid (18:3n‐3), linoleic acid (18:2n‐6) and oleic acid (18:1n‐9) perform as well as MO containing high levels of n‐3 highly unsaturated fatty acids eicosapentanoic acid (20:5n‐3) and docosahexaenoic acid (22:6n‐3) for juvenile red claw crayfish grown indoors lacking natural food items. Further, red claw fed a diet containing BT, which has a high percentage of saturated FA, performed poorly compared with LO and CO in regards to weight gain. It appears that juvenile red claw can be fed diets containing less expensive plant‐based oils with high levels of 18‐carbon unsaturated fatty acids. This could reduce diet costs for producers and allow for profitability.     

Pathology of experimentally-induced, acute toxoplasmosis in macropods

SUMMARY Thirteen Tammar wallabies (Macropus eugenii) were dosed orally with 500, 1000 or 10 000 oocysts of Toxoplasma gondii, as part of a vaccination trial. Eleven animals died of acute toxoplasmosis 9 to 15 days after challenge. The lesions were similar in all animals, consisting of foci of necrosis and inflammation in the intestines, lymphoid tissue, adrenal cortex, heart, skeletal muscle and brain, and severe generalised pulmonary congestion and oedema. Free and intracellular tachyzoites of Toxoplasma were associated with the lesions. The remaining 2 animals had shown no signs of disease when euthanased four months after challenge. Small, focal, non-suppurative inflammatory lesions were seen in brain, heart and skeletal muscle of these animals and chronic Toxoplasma infection was confirmed by mouse inoculation.     

Single-dose pharmacokinetics of cefazolin in bovine synovial fluid after intravenous regional injection

Gagnon, H., Ferguson, J.G., Papich, M.G., Bailey, J.V. Single-dose pharmacokinetics of cefazolin in bovine synovial fluid after intravenous regional injection. J. vet. Pharmacol. Therap. 17, 31–37.
The pharmacokinetic properties of cefazolin in the synovial fluid of the tibiotarsal joint were determined in 10 healthy mature cattle after intravenous regional injection of 2 50 mg cefazolin. A pneumatic tourniquet was positioned proximal to the tibiotarsal joint and the intravenous injection was performed distal to the tourniquet. Synovial fluid concentrations of cefazolin increased in the first 30 mm and fluctuated between 54.7 ± 11.0 g/ml (mean ± SEM) and 73.2 ± 13.2 g/ml in the following 90 min while the tourniquet remained inflated. After tourniquet removal, synovial fluid concentration-time curves followed first-order one-compartment model decay in most of the animals with an elimination half-life of 0.82 h (harmonic mean). Therapeutic concentrations of cefazolin in the synovial fluid of normal joints were reached and this injection technique could be used as an alternative to systemic administration of antibiotics to provide adequate concentrations in a localized area.     

Estimating the mass of asteroid 253 mathilde from tracking data during the NEAR flyby

The terminal navigation of the Near Earth Asteroid Rendezvous (NEAR) spacecraft during its close flyby of asteroid 253 Mathilde involved coordinated efforts to determine the heliocentric orbits of the spacecraft and Mathilde and then to determine the relative trajectory of the spacecraft with respect to Mathilde. The gravitational perturbation of Mathilde on the passing spacecraft was apparent in the spacecraft tracking data. As a result of the accurate targeting achieved, these data could be used to determine Mathilde's mass as 1.033 (+/- 0.044) x 10(20) grams. Coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a low bulk density for Mathilde of 1.3 grams per cubic centimeter.     

Tracing the origins of White Tip disease of Cirsium arvense and its causal agent,Phoma macrostoma

Cirsium arvense (Asteraceae) is known as creeping thistle in its native range in the UK and Canada thistle in its invasive North American range. Recently, the fungus Phoma macrostoma was registered in Canada as a bioherbicide in turfgrass, where it causes severe chlorosis (White Tip disease) and death of C. arvense and other broadleaved weeds. It was hypothesised that the disease originated in the UK on its thistle host and, therefore, that fungal isolates from both countries should be biologically and genetically similar. Twenty‐six strains in the genus Phoma– isolated during surveys in the UK – were compared morphologically with the type culture of P. macrostoma, tested for bioherbicidal activity using the inoculum mat bioassay and genetically screened with bioherbicide‐specific primers. White tip disease was found to be restricted to the eastern and southern counties of England. Phoma macrostoma was isolated consistently from diseased bleached tissues. Bioherbicidal isolates of P. macrostoma occupy a unique clade, which is phylogenetically distinct but morphologically indistinguishable from the type culture. Most isolates from the UK had the same bioherbicidal activity and similar genetic make‐up as strain SRC 94‐44B, the active ingredient in the registered Canadian product. The origin of all bioherbicidal strains found to date has a clear presence in both Canada and the UK, with strong genetic similarities, supporting the view of a common ancestry. Thus, on the evidence presented, the ‘white tip’ clade of P. macrostoma evolved in southern England. Therefore, the bioherbicide based on strain SRC 94‐44B should also be eligible for registration in the UK, based on the pest risk assessment data already available.