What factors influence the career decisions of young veterinarians?     

TJ HEATH 《Australian veterinary journal》1996,74(4):289-290

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The diagnosis and treatment of a thoracic abscess in an alpaca     

JE ADOLF  NL DYKES  S SEMEVOLOS  TJ DIVERS 《Australian veterinary journal》2001,79(10):675-679

A 6-month-old alpaca presented for lethargy, failure to thrive and leucocytosis. Diagnostic procedures, including thoracic ultrasound, radiographs and a computed tomography scan, were used to document a thoracic mass. Based on appearance and ultrasound-guided aspiration of purulent material, the mass was determined to be a large abscess. The abscess was treated with surgical drainage and long-term antibiotic therapy. The origin of this thoracic abscess was felt to be the caudal mediastinum, secondary to bacterial seeding of the caudal mediastinal lymph nodes. Although an aetiological agent was not definitively determined, the most likely was Actinomyces spp or Arcanobacterium pyogenes. The alpaca made a complete recovery following treatment.  相似文献   

Stratospheric Mean Ages and Transport Rates from Observations of Carbon Dioxide and Nitrous Oxide     

KA Boering  SC Wofsy  BC Daube  HR Schneider  M Loewenstein  JR Podolske  TJ Conway 《Science (New York, N.Y.)》1996,274(5291):1340-1343

Measurements of stratospheric carbon dioxide (CO2) and nitrous oxide (N2O) concentrations were analyzed to investigate stratospheric transport rates. Temporal variations in tropospheric CO2 were observed to propagate into the stratosphere, showing that tropospheric air enters the lower tropical stratosphere continuously, ascends, and is transported rapidly (in less than 1 month) to both hemispheres. The mean age A of stratospheric air determined from CO2 data is approximately 5 years in the mid-stratosphere. The mean age is mathematically equivalent to a conserved tracer analogous to exhaust from stratospheric aircraft. Comparison of values for A from models and observations indicates that current model simulations likely underestimate pollutant concentrations from proposed stratospheric aircraft by 25 to 100 percent.  相似文献   

Growth rates of phosphate nodules from the continental margin off peru     

Burnett WC  Beers MJ  Roe KK 《Science (New York, N.Y.)》1982,215(4540):1616-1618

Modern sea-floor phosphorite nodules sampled from off the coast of Peru are shown to grow at rates of millimeters per thousand years in spite of the fact that the measured accumulation rates of the underlying sediment are two to four orders of magnitude faster. Phosphate nodules grow downward into soft sediment, and the rates of phosphorus accumulation into nodules are approximately equal to the upward diffusive flux of dissolved phosphate inferred from pore water profiles. These results demonstrate that phosphorus in nodules originates from regeneration in sediments rather than as a result of direct precipitation from bottom waters.  相似文献   

Melting of (Mg,Fe)2SiO4 at the Core-Mantle Boundary of the Earth     

KG Holland  TJ Ahrens 《Science (New York, N.Y.)》1997,275(5306):1623-1625

The lower mantle of the Earth is believed to be largely composed of (Mg,Fe)O (magnesiowustite) and (Mg,Fe)SiO3 (perovskite). Radiative temperatures of single-crystal olivine [(Mg0.9,Fe0.1)2SiO4] decreased abruptly from 7040 +/- 315 to 4300 +/- 270 kelvin upon shock compression above 80 gigapascals. The data indicate that an upper bound to the solidus of the magnesiowustite and perovskite assemblage at 4300 +/- 270 kelvin is 130 +/- 3 gigapascals. These conditions correspond to those for partial melting at the base of the mantle, as has been suggested occurs within the ultralow-velocity zone beneath the central Pacific.  相似文献   

The Effects of Salinity on Reproductive Performance of Florida Red Tilapia   总被引：2，自引：0，他引：2  

Wade O.  Watanabe Kelly M.  Burnett  Bori L.  Olla  Robert I.  Wicklund 《Journal of the World Aquaculture Society》1989,20(4):223-229

The reproductive performance of yearling Florida red tilapia broodstock was studied in laboratory aquaria at salinities of 1 (freshwater), 9, 18, 27 and 36 ppt under controlled photoperiod (14 L:10 D) and temperature (28 C).
Spawning was observed at all salinities, although egg production per unit female weight at each spawn was significantly higher at 1 ppt than at higher salinities. An inhibitory effect of salinity on reproductive performance was evidenced by a trend toward lower fertilization, hatching, and survival of prejuveniles with increasing salinity. Fry production per unit female weight declined at salinities above 18 ppt. The results suggest that Florida red tilapia broodstock may be maintained under salinities as high as 18 ppt without impairing fry production, suggesting that hatchery production in brackishwater would be practical in areas where freshwater resources are limiting.  相似文献   

The Fermi Gamma-Ray Space Telescope discovers the pulsar in the young galactic supernova remnant CTA 1     

Abdo AA  Ackermann M  Atwood WB  Baldini L  Ballet J  Barbiellini G  Baring MG  Bastieri D  Baughman BM  Bechtol K  Bellazzini R  Berenji B  Blandford RD  Bloom ED  Bogaert G  Bonamente E  Borgland AW  Bregeon J  Brez A  Brigida M  Bruel P  Burnett TH  Caliandro GA  Cameron RA  Caraveo PA  Carlson P  Casandjian JM  Cecchi C  Charles E  Chekhtman A  Cheung CC  Chiang J  Ciprini S  Claus R  Cohen-Tanugi J  Cominsky LR  Conrad J  Cutini S  Davis DS  Dermer CD  de Angelis A  de Palma F  Digel SW  Dormody M  do Couto E Silva E  Drell PS 《Science (New York, N.Y.)》2008,322(5905):1218-1221

Energetic young pulsars and expanding blast waves [supernova remnants (SNRs)] are the most visible remains after massive stars, ending their lives, explode in core-collapse supernovae. The Fermi Gamma-Ray Space Telescope has unveiled a radio quiet pulsar located near the center of the compact synchrotron nebula inside the supernova remnant CTA 1. The pulsar, discovered through its gamma-ray pulsations, has a period of 316.86 milliseconds and a period derivative of 3.614 x 10(-13) seconds per second. Its characteristic age of 10(4) years is comparable to that estimated for the SNR. We speculate that most unidentified Galactic gamma-ray sources associated with star-forming regions and SNRs are such young pulsars.  相似文献   

Components of electroencephalographic responses to slaughter in halothane-anaesthetised calves: Effects of cutting neck tissues compared with major blood vessels     

TJ Gibson  CB Johnson  JC Murrell  JP Chambers  KJ Stafford  DJ Mellor 《New Zealand veterinary journal》2013,61(2):84-89

AIM: To identify whether cutting neck tissues or cutting major blood vessels initiates the mechanisms responsible for electroencephalographic (EEG) responses to slaughter by ventral-neck incision without prior stunning in halothane-anaesthetised calves.

METHODS: Calves were assigned to two groups, viz transection of neck tissues with intact blood circulation through the brain (n=10), or transection of the major blood vessels of the neck but not most other neck tissues (n=7). They were minimally anaesthetised with halothane, using an established anaesthesia protocol. The animals in the neck-tissue transection group had their carotid arteries and jugular veins exposed and cannulated proximal and distal to the proposed site of subsequent ventral-neck incision; this diverted blood fl ow through these vessels so that cerebral perfusion and drainage were preserved. In animals in the blood-vessel transection group, the carotid arteries and jugular veins were exposed bilaterally by surgical dissection. They were then transected without further damage to the remaining structures of the neck. Changes in the median frequency (F50), 95% spectral edge frequency (F95), total power of the EEG (Ptot), and arterial blood pressure were compared within each group before and after neck-tissue or blood-vessel transection, and between groups following treatments.

RESULTS: Neck-tissue transection resulted in little overall change in the F50, an increase in the F95, and an initial increase in Ptot followed by a transient decrease and eventual return to pre-treatment values. There was between-animal variation in these EEG parameters. Transection of the major blood vessels of the neck resulted in a decrease in F50 in most animals; changes in F95 were highly variable, and there was a decrease in Ptot.

CONCLUSIONS: The EEG responses seen following necktissue and blood-vessel transection were qualitatively distinct, and suggested that cutting neck tissues caused greater noxious sensory input than transection of only the major blood vessels of the neck. These observations support the conclusion that the EEG responses seen after ventral-neck incision in intact animals are primarily due to noxious stimulation as a result of incision of ventral-neck tissues and not mainly as a result of loss of blood flow through the brain.  相似文献   

Blood metabolites and body temperature of single calves between 1 and 4 days of age in a dairy herd in New Zealand     

TJ Diesch  KJ Stafford  RN Ward 《New Zealand veterinary journal》2013,61(5):256-260

AIM: Using specified indices, to determine the nutritional and thermal status of calves between 1 and 4 days of age.

METHODS: After birth, calves (n=106) were collected daily, according to farm practice. Over the following 4 days a jugular blood sample and rectal temperature were taken twice daily before feeding. Plasma concentrations of glucose, beta-hydroxybutyrate and urea, and gamma-glutamyl transferase (GGT) activities were determined. The significance of differences in plasma composition and rectal temperature between calves whose birth had been assisted or unassisted, and between calves with low and high plasma GGT activities 24 h after birth, was determined using repeated measures analysis of varianc

RESULTS: There were no marked differences in plasma metabolite levels or body temperature of assisted and unassisted calves. Calves that had high plasma GGT activities 24 h after birth had higher plasma glucose concentrations over the 4 days than calves that had low plasma GGT activities (p<0.001). Overall, compared to published data on poorly-fed and hypothermic calves, calves in this study were normoglycaemic, their plasma beta-hydroxybutyrate and urea concentrations were low and their rectal temperatures were normal, indicating that they were well fed and did not become hypothermic.

CONCLUSIONS: The nutritional and thermal status of at least 90% of the calves was compatible with good health and survival during the first 4 days after birth.  相似文献   

Seminoma in a southern black rhinoceros (Diceros bicornis minor): diagnosis, surgical management and effect on fertility     

TJ Portas  TB Hildebrandt  BR Bryant  F Göritz  R Hermes 《Australian veterinary journal》2010,88(1-2):57-60

A testicular mass was identified by ultrasonography performed during a routine reproductive evaluation of an adult male southern black rhinoceros ( Diceros bicornis minor ). Histological examination of a testicular biopsy supported a presumptive diagnosis of testicular neoplasia. Hemi-castration was performed to excise the affected testis and a pathological diagnosis of a seminoma was made. Assessment of semen suggested reduced fertility as a consequence of the neoplastic process, but hemi-castration prevented further growth and metastasis of the tumour and ensured the animal's breeding potential. This is the second documented case of a seminoma in a rhinoceros species and the first case in a black rhinoceros.  相似文献