澳大利亚森林大火对我国森林防火工作的启示     

武警森林指挥部 《森林防火》2009,(2):56-58

通过对澳大利亚维多利亚州森林大火相关情况的分析,结合我国森林防火特点,从国家和武警森林部队两个层面提出了加强森林防火工作的对策和措施.  相似文献   

Recurrence rates and clinical outcome for dogs with grade II mast cell tumours with a low AgNOR count and Ki67 index treated with surgery alone          下载免费PDF全文

J. Smith  M. Kiupel  J. Farrelly  R. Cohen  G. Olmsted  J. Kirpensteijn  B. Brocks  G. Post 《Veterinary and comparative oncology》2017,15(1):36-45

Grade II mast cell tumours (MCT) are tumours with variable biologic behaviour. Multiple factors have been associated with outcome, including proliferation markers. The purpose of this study was to determine if extent of surgical excision affects recurrence rate in dogs with grade II MCT with low proliferation activity, determined by Ki67 and argyrophilic nucleolar organising regions (AgNOR). Eighty‐six dogs with cutaneous MCT were evaluated. All dogs had surgical excision of their MCT with a low Ki67 index and combined AgNORxKi67 (Ag67) values. Twenty‐three (27%) dogs developed local or distant recurrence during the median follow‐up time. Of these dogs, six (7%) had local recurrence, one had complete and five had incomplete histologic margins. This difference in recurrence rates between dogs with complete and incomplete histologic margins was not significant. On the basis of this study, ancillary therapy may not be necessary for patients with incompletely excised grade II MCT with low proliferation activity.  相似文献   

The role of discharge variation in scaling of drainage area and food chain length in rivers     

Sabo JL  Finlay JC  Kennedy T  Post DM 《Science (New York, N.Y.)》2010,330(6006):965-967

Food chain length (FCL) is a fundamental component of food web structure. Studies in a variety of ecosystems suggest that FCL is determined by energy supply, environmental stability, and/or ecosystem size, but the nature of the relationship between environmental stability and FCL, and the mechanism linking ecosystem size to FCL, remain unclear. Here we show that FCL increases with drainage area and decreases with hydrologic variability and intermittency across 36 North American rivers. Our analysis further suggests that hydrologic variability is the mechanism underlying the correlation between ecosystem size and FCL in rivers. Ecosystem size lengthens river food chains by integrating and attenuating discharge variation through stream networks, thereby enhancing environmental stability in larger river systems.  相似文献   

Evaluation of a multidrug chemotherapy protocol with mitoxantrone based maintenance (CHOP-MA) for the treatment of canine lymphoma     

A. T. Daters  G. E. Mauldin  G. N. Mauldin  E. M. Brodsky  G. S. Post 《Veterinary and comparative oncology》2010,8(1):11-22

The purpose of this study was to evaluate the efficacy of adding mitoxantrone to a cyclophosphamide, doxorubicin, vincristine, l -asparaginase and prednisone containing protocol. Sixty-five dogs with multicentric lymphoma were evaluated for overall remission and survival times. Remission and survival time versus stage, substage, pretreatment hypercalcaemia and pretreatment steroid administration were also evaluated. Overall median remission for dogs with multicentric lymphoma was 302 days and overall median survival was 622 days. Of the dogs with multicentric lymphoma, 23 (35%) received all scheduled mitoxantrone doses. Only median survival versus substage was found to be significant (substage a median survival was 679 days and substage b median survival was 302 days, P = 0.025). Increasing the total combined dose of doxorubicin and mitoxantrone may improve remission times when compared with historical controls, and further studies are needed to determine how best to utilize mitoxantrone in multidrug chemotherapy protocols for canine multicentric lymphoma.  相似文献   

Interactions between herbivory and warming in aboveground biomass production of arctic vegetation     

Christian Pedersen  Eric Post 《BMC ecology》2008,8(1):1-12

Background

In the androdioecious nematode Caenorhabditis elegans virtually all progeny produced by hermaphrodite self-fertilization is hermaphrodite while 50% of the progeny that results from cross-fertilization by a male is male. In the standard laboratory wild type strain N2 males disappear rapidly from populations. This is not the case in some other wild type isolates of C. elegans, among them the Hawaiian strain CB4856.

Results

We determined the kinetics of the loss of males over time for multiple population sizes and wild isolates and found significant differences. We performed systematic inter- and intra-strain crosses with N2 and CB4856 and show that the males and the hermaphrodites contribute to the difference in male maintenance between these two strains. In particular, CB4856 males obtained a higher number of successful copulations than N2 males and sired correspondingly more cross-progeny. On the other hand, N2 hermaphrodites produced a higher number of self-progeny, both when singly mated and when not mated.

Conclusion

These two differences have the potential to explain the observed variation in male persistence, since they should lead to a predominance of self-progeny (and thus hermaphrodites) in N2 and, at the same time, a high proportion of cross-progeny (and thus the presence of males as well as hermaphrodites) in CB4856.  相似文献   

Gradient analysis of an eastern sand savanna's woody vegetation,and its long-term responses to restored fire processes     

Alan Haney  Marlin Bowles  Steven Apfelbaum  Emily Lain  Tom Post 《Forest Ecology and Management》2008

Little information is available comparing historic and modern sand savannas, and how remnants respond to restored fire. We compared short- and long-term effects of restored fire on the Tefft Savanna, a 197 ha eastern sand savanna in northwest Indiana that had undergone three decades of fire protection. U.S. Public Land Survey data from Tefft in 1833 indicate black and white oak barrens, and pin oak savanna, with trees averaging 50 stems/ha and 4 m²/ha basal area. We used ordination and a digital elevation model to assess topographic distribution of tree species in 1986. In 1986, we also compared initial effects of high- and low-intensity dormant season fire on woody vegetation among nine blocks containing black oak, white oak, and pin oak stands. Twenty years later, we compared the same blocks, all of which had been burned three times per decade with low-intensity fires. In 1986, black oak, white oak and pin oak occurred across a gradient of decreasing elevation and slope. At that time, unburned black oak and white oak stands averaged >400 stems/ha and about 10 m²/ha basal area, and their smaller size classes contained non-oak woody vegetation that apparently had invaded with fire exclusion. After initial burns, black oak and white oak stands receiving high-intensity fire averaged <200 stems/ha and had significantly lower oak canopy cover and basal area than unburned stands. Stands receiving low-intensity fire had intermediate oak canopy cover, with basal area similar to unburned stands. Pin oak stands were more fire-resistant, apparently because spring flooding often reduced fire effects. Density, cover and basal area of non-oak tree species were much lower than oaks, and were not reduced by initial burning. Repeated low-intensity burning over 20 years tended to maintain structure caused by initial fires. However, it reduced lower size class stem densities, promoted post-fire sprouting into the shrub layer, and allowed oak basal area to increase in larger size classes. Time since fire regulated shrub layer structure on a 4-year cycle. Density and cover of trees and shrubs returned to pre-burn conditions by the second and fourth growing seasons after fire, respectively, with non-oak tree species exceeding pre-burn cover and density by the fourth season. These results suggest that high-intensity fire is more important than repeated low-intensity burning in structuring and restoring eastern sand savanna, and that non-oak tree species, once established, may be resistant to low-intensity fire.  相似文献   

Black soil blindness: A new mycotoxicosis of cattle grazing Corallocytostroma-infected Mitchell grass (Astrebla spp)     

TF JUBB  DC MAIN†  AA MITCHELL†  RG SHIVAS†  KW DE  WITTE‡ 《Australian veterinary journal》1996,73(2):49-51

A new, fatal mycotoxicosis of cattle has been recognised in north-western Australia. A feeding trial confirmed the toxicity of a previously unknown species of Corallocytostroma that grows on Mitchell grass (Astrebla spp). The disease has been colloquially named ‘black soil blindness’ because its most prominent features are its confinement to pastures on black soil, and blindness and death of affected animals. Over 500 cattle have died and considerable subclinical disease is present. Above average wet season rainfall and extended growing seasons may explain the emergence of the fungus. The disease is important because cattle production in large areas of Australia utilise Mitchell grass pastures.  相似文献   

Nonhematopoietic hepatic neoplasms in cats: 21 cases (1983-1988).     

G Post  A K Patnaik 《Journal of the American Veterinary Medical Association》1992,201(7):1080-1082

Nonhematopoietic hepatic neoplasms (n = 25) were diagnosed in 21 cats during a 5.5-year period. Thirteen of the neoplasms were benign bile duct adenomas and 12 were malignant, 6 of which were bile duct adenocarcinomas. All cats were greater than or equal to 10 years old, and 14 were male. Main clinical signs were anorexia and lethargy, and 15 of 21 cats had hepatomegaly. All 21 cats were feline leukemia virus-test negative. Although there was a trend toward high activities of serum alanine transaminase and aspartate transaminase, neither clinical signs nor enzyme activity were specific for diagnosis of hepatic neoplasia in the cats of this study.  相似文献   

Improving performance of finishing pigs with added valine,isoleucine, and tryptophan: validating a meta-analysis model     

Hayden R Kerkaert  Henrique S Cemin  Jason C Woodworth  Joel M DeRouchey  Steve S Dritz  Mike D Tokach  Robert D Goodband  Keith D Haydon  Chad W Hastad  Zach B Post 《Journal of animal science》2021,99(1)

Based on results of a recent meta-analysis, we hypothesized that increased dietary Val, Ile, or Trp could correct possible amino acid interactions because of excess Leu in diets containing high levels of corn protein, namely dried distiller’s grains with solubles (DDGS). A total of 1,200 pigs (PIC TR4 × (Fast LW × PIC L02); initially 33.6 ± 0.6 kg) were used in a 103-d study. The 6 dietary treatments were corn–soybean meal (SBM)-DDGS-based as follows: (1) high SBM and low level of l-Lys HCl (HSBM), (2) high l-Lys HCl and moderate Ile, Val, Trp (AA above NRC 2012 estimates; NC), (3) moderate l-Lys HCl and high Ile, Val, and Trp (PC), and PC with either increased (4) L-Val (PC+Val), (5) L-Ile (PC+Ile), or (6) L-Trp (PC+Trp). Pigs fed the NC diet were predicted to have the poorest average daily gain (ADG), the PC diet to be intermediate, and pigs fed the HSBM, PC+Val, PC+Ile, and PC+Trp have the same and highest predicted ADG. In the grower period (34 to 90 kg), ADG was greater (Ρ < 0.05) for the pigs fed HSBM and PC+Val diets than the NC with pigs fed other diets intermediate. Pigs fed HSBM were more (Ρ < 0.05) efficient (G:F) than the NC and PC with pigs fed other diets intermediate. In the finisher period (90 to 136 kg), ADG was greater (Ρ < 0.05) for pigs fed PC+Ile than that of the NC with pigs fed other diets intermediate. Pigs fed PC+Val had greater (Ρ < 0.05) average daily feed intake (ADFI) than the NC with pigs fed other diets intermediate. However, PC+Ile pigs were more (Ρ < 0.05) efficient than PC+Val with pigs fed other diets intermediate. Overall, ADG was greater (Ρ < 0.05) for pigs fed HSBM, PC+Val, and PC+Ile diets than the NC with pigs fed other diets intermediate. Pigs fed the PC+Val diet had greater (Ρ < 0.05) ADFI than the NC with pigs fed other diets intermediate. No differences were detected between treatments for overall G:F or other carcass characteristics. In conclusion, increasing Val or Ile in high l-Lys-HCl-DDGS-based diets improved growth performance compared with pigs fed diets containing high levels of l-Lys HCl without added Val and Ile. These results present evidence that the recently developed meta-analysis can predict the relative differences in overall ADG for pigs fed the NC, PC, PC+Val, and PC+Ile diets; however, the predicted G:F was less accurate. The data demonstrate that the negative effects of high Leu concentrations in corn-DDGS-based diets can be reversed by increasing the ratios of Val and Ile relative to Lys.  相似文献   

OPTIMIZATION DESIGN OF ADVANCED CORRECTION OF THE CONTROL SYSTEM BY A PASSIVE NETWORK     

Yang Gesheng Post Box  Baojishi  Shanxi Province 《保鲜与加工》1992,(2)

Optimization design of correction of the control systemby a passive network is studied in this paper.The design method guan-rantees collocation of a closed loop pole in a desired position,but alsominimizes the gain of the system amplifier,thus making the technicalrealization of the system easier.The design method is proved in thepaper.  相似文献