Characterizing historical and modern fire regimes in Michigan (USA): A landscape ecosystem approach   总被引：4，自引：0，他引：4  

Cleland  David T.  Crow  Thomas R.  Saunders  Sari C.  Dickmann  Donald I.  Maclean  Ann L.  Jordan  James K.  Watson  Richard L.  Sloan  Alyssa M.  Brosofske  Kimberley D. 《Landscape Ecology》2004,19(3):311-325

We studied the relationships of landscape ecosystems to historical and contemporary fire regimes across 4.3 million hectares in northern lower Michigan (USA). Changes in fire regimes were documented by comparing historical fire rotations in different landscape ecosystems to those occurring between 1985 and 2000. Previously published data and a synthesis of the literature were used to identify six forest-replacement fire regime categories with fire rotations ranging from very short (<100 years) to very long (>1,000 years). We derived spatially-explicit estimates of the susceptibility of landscape ecosystems to fire disturbance using Landtype Association maps as initial units of investigation. Each Landtype Association polygon was assigned to a fire regime category based on associations of ecological factors known to influence fire regimes. Spatial statistics were used to interpolate fire points recorded by the General Land Office. Historical fire rotations were determined by calculating the area burned for each category of fire regime and dividing this area by fifteen (years) to estimate area burned per annum. Modern fire rotations were estimated using data on fire location and size obtained from federal and state agencies. Landtype Associations networked into fire regime categories exhibited differences in both historical and modern fire rotations. Historical rotations varied by 23-fold across all fire rotation categories, and modern forest fire rotations by 13-fold. Modern fire rotations were an order of magnitude longer than historical rotations. The magnitude of these changes has important implications for forest health and understanding of ecological processes in most of the fire rotation categories that we identified.This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献   

THE THIRTEENTH NEW ENGLAND INTERCOLLEGIATE GEOLOGICAL EXCURSION     

Cleland HF 《Science (New York, N.Y.)》1915,42(1088):634-635

  相似文献   

THE INTERCOLLEGIATE GEOLOGICAL EXCURSION     

Cleland HF 《Science (New York, N.Y.)》1907,26(671):643

  相似文献   

Auxin and wall extensibility: reversibility of auxin-induced wall-loosening process   总被引：3，自引：0，他引：3  

R Cleland 《Science (New York, N.Y.)》1968,160(824):192-194

The reversible nature of the auxin-mediated loosening of the cell wall is shown by the ability of respiratory inhibitors to cause the loss of the auxin-induced increase in wall extensibility without affecting the basal extensibility of the wall. This reversibility makes it unlikely that wall loosening is mediated by enzymes, such as cellulase and beta-glucanase, which degrade polysaccharides, since their action is essentially irreversible.  相似文献   

Effects of storage conditions in vitro on the assay of chick liver glycogen.     

M E Cleland  D W Bannister 《British poultry science》1979,20(3):307-310

1. The reproducibility of an enzymic method for assaying chick liver glycogen was found to be +/- 1.6%. 2. Storage of liver at either -21 or -70 degrees C for up to 4 weeks, after freezing in liquid nitrogen, had no significant effect on glycogen concentration. However, the concentration of free glucose increased by about 50% during this time. 3. Storage of liver in ice-cold saline for up to 3 h proved unsatisfactory because of a significant loss of glycogen. 4. There was no significant difference in immediate glycogen concentration in liver tissue that was freeze-clamped, frozen in liquid nitrogen or collected into ice-cold saline. The free glucose concentration was higher, when estimated immediately after, with the latter two methods of collection of liver tissue.  相似文献   

An investigation of 11 outbreaks of foot-and-mouth disease in villages in northern Thailand     

P. C. Cleland  P. Chamnanpood  F. C. Baldock  L. J. Gleeson   《Preventive veterinary medicine》1995,22(4):293-302

The results of investigations of 11 outbreaks of foot-and-mouth disease in villages in northern Thailand are described. The causative virus was Asia in one in seven outbreaks, Type O in two outbreaks and unknown in two outbreaks. The most probable sources of the outbreaks were co-mingling of cattle and/or buffalo with livestock from an infected neighbouring village (four) and recent introductions of infected cattle from a public livestock market (two) while the probable source could not be determined in five outbreaks. Attack rates in cattle and buffalo ranged from 0.28% to 50.9% but no pigs became sick during any of the outbreaks. Most outbreaks lasted 4 weeks or less. Adult cattle and buffalo were at higher risk of becoming a case when compared with work cattle. Beef cattle were at higher risk than buffalo and adult cattle and buffalo were at higher risk than calves less than 1 year of age. There was significant clustering of cases within households. Serological investigations indicated that many unaffected animals were probably not exposed to virus during the outbreaks. We concluded that close contact between animals was the main method of spread and that differences in attack rates between animal classes reflected differences in animal management. We further concluded that simple quarantine of early cases during outbreaks is likely to be effective in reducing spread within and between villages.  相似文献   

Nonsurgical periodontal therapy     

Cleland WP 《Clinical Techniques in Small Animal Practice》2000,15(4):221-225

The primary etiology of periodontal disease is bacterial infection. Bacteria exist as a biofilm (plaque) on the tooth and soft-tissue surfaces of the mouth. Biofilm is extremely resistant to antimicrobial activity. To effectively treat periodontal disease, the bacterial load must be reduced to allow healing of the inflamed tissues. Reduction of the bacterial load can be accomplished by surgical methods, nonsurgical methods, or a combination of the two. This article focuses on the nonsurgical treatment of periodontal disease. A thorough oral examination, which includes visual inspection and the use of a periodontal probe, is needed to determine the best therapy. Supragingival cleaning with power and hand scalers is the first step in the therapy process. The next step, subgingival scaling, is necessary to remove bacteria that are in direct contact with the periodontium. Effective subgingival plaque removal is time intensive and requires motivation, manual dexterity, and meticulous technique. Most veterinarians and veterinary technicians lack the training, instruments, and time to remove subgingival plaque effectively. To improve therapeutic results, adjunctive therapy in the form of oral systemic antibiotics or a locally applied doxycycline-containing polymer may be used. The success of periodontal therapy also is dependent on dental home care that takes place after professional treatment. The veterinarian and staff must be willing to educate and reinforce the dental home care efforts of the pet owner.  相似文献   

Village level risk factors for foot-and-mouth disease in Northern Thailand   总被引：1，自引：0，他引：1  

Paul C. Cleland  F. Chris Baldock  Pornchai Chamnanpood  Laurence J. Gleeson 《Preventive veterinary medicine》1996,26(3-4):253-261

A study was undertaken in northern Thailand to identify factors which put some villages at higher risk of foot-and-mouth disease (FMD) outbreaks than others. The number of FMD outbreaks experienced in the previous 5 years and data on 145 putative risk factors were obtained by interview from 60 villages during 1991–1992. Univariable analyses identified 27 factors for further investigation using logistic regression. When villages were classified into three FMD frequency groups of zero to one, two to three or four or more outbreaks in the last 5 years, the important factors explaining the differences in risk were the total number of cattle and buffaloes purchased in the previous year, the number of neighbouring villages which shared a common water source and whether agriculture was the most important source of cash income for the village. These factors were also the most important variables in explaining the difference in risk when comparing villages with zero or one outbreak with those having four or more. We concluded that the greatest impact on reducing spread of FMD among villages would be obtained through the development of strategies to reduce the likelihood of introduction through livestock purchases and for villagers to take greater care when livestock are grazed with those from neighbouring villages and when sharing common water supplies.  相似文献   

Coherent state evolution in a superconducting qubit from partial-collapse measurement     

Katz N  Ansmann M  Bialczak RC  Lucero E  McDermott R  Neeley M  Steffen M  Weig EM  Cleland AN  Martinis JM  Korotkov AN 《Science (New York, N.Y.)》2006,312(5779):1498-1500

Measurement is one of the fundamental building blocks of quantum-information processing systems. Partial measurement, where full wavefunction collapse is not the only outcome, provides a detailed test of the measurement process. We introduce quantum-state tomography in a superconducting qubit that exhibits high-fidelity single-shot measurement. For the two probabilistic outcomes of partial measurement, we find either a full collapse or a coherent yet nonunitary evolution of the state. This latter behavior explicitly confirms modern quantum-measurement theory and may prove important for error-correction algorithms in quantum computation.  相似文献   

A SUGGESTION FOR MAKING OUR SCIENTIFIC PUBLICATIONS MORE USEFUL AND OUR POST-OFFICES A CENTER OF INFORMATION     

Cleland HF 《Science (New York, N.Y.)》1921,53(1365):180-182

  相似文献