A Large Drop in Atmospheric 14C/12C and Reduced Melting in the Younger Dryas, Documented with 230Th Ages of Corals     

Edwards RL  Beck JW  Burr GS  Donahue DJ  Chappell JM  Bloom AL  Druffel ER  Taylor FW 《Science (New York, N.Y.)》1993,260(5110):962-968

Paired carbon-14 ((14)C) and thorium-230((230)Th) ages were determined on fossil corals from the Huon Peninsula, Papua New Guinea. The ages were used to calibrate part of the (14)C time scale and to estimate rates of sea-level rise during the last deglaciation. An abrupt offset between the (14)C and (230)Th ages suggests that the atmospheric (14)C/(12)C ratio dropped by 15 percent during the latter part of and after the Younger Dryas (YD). This prominent drop coincides with greatly reduced rates of sea-level rise. Reduction of melting because of cooler conditions during the YD may have caused an increase in the rate of ocean ventilation, which caused the atmospheric (14)C/(12)C ratio to fall. The record of sea-level rise also shows that globally averaged rates of melting were relatively high at the beginning of the YD. Thus, these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the Mississippi to the St. Lawrence River triggered the YD event.  相似文献   

NEAR's flyby of 253 mathilde: images of a C asteroid     

J Veverka  P Thomas  A Harch  B Clark  JF Bell  B Carcich  J Joseph  C Chapman  W Merline  M Robinson  M Malin  LA McFadden  S Murchie  SE Hawkins  R Farquhar  N Izenberg  A Cheng 《Science (New York, N.Y.)》1997,278(5346):2109-2114

On 27 June 1997, the Near Earth Asteroid Rendezvous (NEAR) spacecraft flew within 1212 kilometers of asteroid 253 Mathilde. Mathilde is an irregular, heavily cratered body measuring 66 kilometers by 48 kilometers by 46 kilometers. The asteroid's surface is dark (estimated albedo between 0.035 and 0.050) and similar in color to some CM carbonaceous chondrites. No albedo or color variations were detected. The volume derived from the images and the mass from Doppler tracking of the spacecraft yield a mean density of 1.3 +/- 0.2 grams per cubic centimeter, about half that of CM chondrites, indicating a porous interior structure.  相似文献   

Detection and Characterization of the Cumulene Carbenes H2C5 and H2C6     

MC McCarthy  MJ Travers  A Kovacs  W Chen  SE Novick  CA Gottlieb  P Thaddeus 《Science (New York, N.Y.)》1997,275(5299):518-520

Two cumulene carbenes, H2C5 and H2C6, were detected in a supersonic molecular beam by Fourier transform microwave spectroscopy. Their rotational and leading centrifugal distortion constants were determined with high accuracy, such that the entire radio spectrum can now be calculated. Like the known carbenes H2C3 and H2C4, both molecules have singlet electronic ground states and linear carbon-chain backbones. They can be produced in sufficiently high concentrations in the laboratory that their electronic spectra, expected to lie in the visible, should be readily detectable by laser spectroscopy. The microwave spectra of other, more exotic isomers may be detectable as well.  相似文献   

Diagnostic utility of cerebrospinal fluid analysis in dogs with suspected idiopathic epilepsy     

SE Gilbert  TJ Cardy  S Bertram  F Taylor‐Brown 《Australian veterinary journal》2021,99(1-2):1-5

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Retrospective analysis of 736 cases of canine gastric dilatation volvulus     

KK Song  SE Goldsmid  J Lee  DJ Simpson 《Australian veterinary journal》2020,98(6):232-238

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Long-term survival of four dogs with disseminated Aspergillus terreus infection treated with itraconazole     

SE KELLY  SE SHAW  WT CLARK 《Australian veterinary journal》1995,72(8):311-313

SUMMARY Four dogs with disseminated aspergillosis caused by Aspergillus terreus were treated with oral itraconazole for 190 to 1095 days. Infection was eliminated in 1 dog. Two dogs were treated for 1000 and 1095 days but were eventually euthanased 572 and 485 days after treatment was stopped. At necropsy both dogs had widespread aspergillosis. The fourth dog was euthanased for other reasons after 190 days of treatment when it was showing a good clinical response although there was radiographic evidence that the disease was progressing.  相似文献   

The anticoagulant pindone causes liver damage in the brushtail possum (Trichosurus vulpecula)     

SE JOLLY  CT EASON  C. FRAMPTON  RC GUMBRELL 《Australian veterinary journal》1994,71(7):220-220

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Duration of immunity in cats after vaccination or naturally acquired infection.     

M J Coyne  J H Burr  T D Yule  M J Harding  D B Tresnan  D McGavin 《The Veterinary record》2001,149(18):545-548

The necessity for cats to be vaccinated annually against common pathogens has been questioned because sarcomas have infrequently been reported at the injection site. However, with few exceptions, the duration of immunity induced by vaccination or infection is uncertain, and there may therefore be a risk associated with a decision not to revaccinate. This article reviews the information available about the duration of immunity induced by vaccination or infection in cats, and reveals many shortcomings that make blanket recommendations impossible. Each vaccine must be considered individually.  相似文献   

Gamma irradiation of potatoes: Effects on sugar content,chip color,germination, greening,and susceptibility to mold     

Sigmund Schwimmer  Horace K. Burr  W. O. Harrington  William J. Weston 《American Journal of Potato Research》1957,34(2):31-41

Russet Burbank potatoes that had been stored at 40°F. for 5 months after harvest were irradiated with 5,200 and 14,000 rad of Co⁶⁰ gamma rays. In general, irradiation caused an accumulation of sugars. At 40°F., the sucrose level rose to nearly 3 times that of the control in 16 days following irradiation. Fructose and glucose showed smaller increases and the latter did not accumulate significantly in the tubers given the higher dose of gamma rays. At 70°F., the levels of sucrose and glucose in the irradiated tubers rose above those in the controls, the difference reaching a maximum in 4 days and then declining. Irradiation had no effect on loss of fructose at this temperature. Color of potato chips processed from the irradiated potatoes was in general darker than that of chips from control tubers. The storage-time pattern of color change resembled that of the reducing rather than total sugar. Fourteen thousand rad did not prevent initiation of germination in the tubers but did destroy their sprout-growth apparatus. Although the lower dosage did not prevent initiation and subsequent growth, it prevented the formation of secondary tubers, which appeared on the sprouted control tubers. Furthermore, unlike the controls, the low-dosage potatoes developed branching hair sprouts with no tendency toward apical dominance during the early stages of sprouting. The rate of greening of gamma-irradiated and illuminated tubers was significantly less than that of unirradiated illuminated controls. Evidence is presented that irradiation may increase the susceptibility of potatoes to attack by molds under some conditions.  相似文献   

The effect of different combinations of lignocaine,ketoprofen, xylazine and tolazoline on the acute cortisol response to dehorning in calves     

KJ Stafford  DJ Mellor  SE Todd  RN Ward  CM McMeekan 《New Zealand veterinary journal》2013,61(5):219-226

AIMS: The aims of this study were (a) to evaluate the effect of xylazine and tolazoline, with and without lignocaine, on the cortisol response of calves following amputation dehorning and (b) to assess the effect of a non-steroidal anti-inflammatory drug (ketoprofen) and local anaesthesia on the cortisol response of calves to amputation dehorning.

METHODS: Plasma cortisol concentrations were measured in 100 dehorned or non-dehorned 3-month-old calves over an 8-h period following five different sedative/analgesic or control treatments. Sedative/analgesic treatments were: control (no anaesthesia); local anaesthesia and ketoprofen; local anaesthesia and xylazine; local anaesthesia, xylazine and tolazoline; and xylazine only. Within each sedative/analgesic treatment group, half the calves (n=10 per group) were amputation dehorned and half were not dehorned.

RESULTS: The change in plasma cortisol concentrations in calves dehorned after being given ketoprofen and local anaesthesia did not differ significantly from that of non-dehorned control calves for at least 8 h. In contrast, the cortisol response of dehorned calves not given analgesic drugs peaked 30 min after dehorning and lasted >4 h. Xylazine injected before dehorning significantly reduced but did not eliminate the peak of the cortisol response. When both xylazine and local anaesthesia were administered before dehorning the peak in the cortisol response was virtually eliminated. In the dehorned calves that received xylazine with or without local anaesthesia, cortisol concentration increased significantly 3 h after dehorning and did not return to baseline until at least 5 h later. When tolazoline was administered shortly after xylazine, it caused a marked cortisol response, higher than the response to any other treatment.

CONCLUSIONS: Combining ketoprofen and local anaesthesia minimised the cortisol response, and by inference the pain- induced distress, following amputation dehorning in calves. Xylazine reduced the initial cortisol response to dehorning but not as much as when local anaesthesia was also given. The increase in cortisol concentration from 3–8 h after dehorning in calves given xylazine alone or in combination with local anaesthesia suggests that calves experienced pain-induced distress during this time and that xylazine had no long-term analgesic effect. Tolazoline, used to reverse the sedative effects of xylazine, caused a marked cortisol response in calves via a mechanism which remains unclear.  相似文献