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Median Size (median + size)

Distribution by Scientific Domains

Life Sciences	40%

Selected Abstracts

SOME PROBLEMS WITH ASSESSING COPE'S RULE

EVOLUTION, Issue 8 2008
Andrew R. Solow
Cope's Rule states that the size of species tends to increase along an evolutionary lineage. A basic statistical framework is elucidated for testing Cope's Rule and some surprising complications are pointed out. If Cope's Rule is formulated in terms of mean size, then it is not invariant to the way in which size is measured. If Cope's Rule is formulated in terms of median size, then it is not invariant to the degree of separation between ancestral and descendant species. Some practical problems in assessing Cope's Rule are also described. These results have implications for the empirical assessment of Cope's Rule. [source]

Release of cell contents and comminution of particles of perennial ryegrass herbage during ingestion by dairy cows fed indoors or grazing

GRASS & FORAGE SCIENCE, Issue 3 2006
A. Boudon
Abstract The effect of feeding indoors fresh perennial ryegrass vs. grazing on ingestive behaviour, release of cell contents and comminution of particles during ingestion, as well as on gas production of ingested boli fermented in vitro, was studied. Indoor feeding and grazing were compared using four dairy cows according to a triple reversal design with six periods. Chemical and morphological composition of the ingested herbage was similar for both indoor feeding and grazing treatments. The intake rate was markedly higher indoors compared with grazing [52·1 vs. 22·9 g dry matter (DM) min,1] with heavier boli and less saliva added per gram of DM intake. The proportions of intracellular nitrogen and chlorophyll released during mastication after ingestion of herbage fed indoors were lower, and the median size of the particles in the boli was larger (5·97 vs. 4·44 mm) compared with grazing. As a result, the rate of gas production in vitro was also lower for herbage fed indoors compared with grazing (0·423 vs. 0·469 mL min,1 g,1 incubated DM). Indoor feeding or grazing may have limited consequences in vivo on the kinetics of availability of nutrients for micro-organisms in the rumen, because the consequences of the more extensive physical damage suffered by herbage ingested at grazing could be compensated by a lower intake rate. [source]

Lip cancer in Northern Finland: changing incidence and clinical characteristics

JOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 7 2000
Olli-Pekka Alho
Abstract: A population-based survey was conducted in 35 municipalities in Northern Finland to assess the incidence of lip cancer as well as the patient and tumour characteristics in cases diagnosed between 1983 and 1997. A total of 96 new patients emerged. The age-standardised incidence (per 100,000 years) of lip cancer in men decreased from 4.8 in 1983,1987 to 1.4 in 1993,1997. The incidences in women were 0.30 to 0.36, respectively. The median age of the patients increased from 66 to 73 years through the years. Overall, 90% of the patients had at least one of the known risk factors, namely rural domicile, outdoor occupation or smoking. The median duration of symptoms also remained the same, as did the median size and location of the tumour at diagnosis. In contrast, spread to regional lymph nodes became rare during the period. [source]

A New Apparatus for Particle Impact Tests

PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 4 2003
Yevgeny Petukhov
Abstract Breakage and chipping of particles due to collision with a hard surface is a common occurrence in many conveying and handling systems, such as pneumatic conveying and jet-mills. Studies of the breakage mechanism of particles due to impact and the effect of impact velocity and the number of impacts have been investigated in depth both experimentally and theoretically. In this paper, a new concept and apparatus are introduced for conducting particle impact tests. In most of the published test rigs, particles were accelerated towards a target. In our apparatus, the target moves and hits the particles. Using this concept, the machine can operate in a vacuum, which will reduce errors caused by air streams and turbulence. The performance of the new apparatus is analyzed and the breakage phenomenon is discussed, to some extent, for two materials. The results are presented in terms of the increase in the weight percentage of the feed broken and the decrease in the weight median size as the impact velocity or number of impacts increases. [source]

Stream Restoration in the Upper Midwest, U.S.A.

RESTORATION ECOLOGY, Issue 4 2006
Gretchen G. Alexander
Abstract Restoration activities intended to improve the condition of streams and rivers are widespread throughout the Upper Midwest, U.S.A. As with other regions, however, little information exists regarding types of activities and their effectiveness. We developed a database of 1,345 stream restoration projects implemented from the years 1970 to 2004 for the states of Michigan, Ohio, and Wisconsin in order to analyze regional trends in goals, presence of monitoring, spatial distribution, size, and cost of river restoration projects. We found that data on individual projects were fragmented across multiple federal, state, and county agencies, as well as nonprofit groups and consulting firms. The most common restoration goals reported for this region were in-stream habitat improvement, bank stabilization, water-quality management, and dam removal. The former two were most common in Michigan and Wisconsin, where salmonid fisheries enhancement appeared to be an important concern, whereas water-quality management was most frequent in Ohio. The most common restoration activities were the use of sand traps and riprap, and other common activities were related to the improvement of fish habitat. The median cost was $12,957 for projects with cost data, and total expenditures since 1990 were estimated at $444 million. Over time, the cost of individual projects has increased, whereas the median size has decreased, suggesting that restoration resources are being spent on smaller, more localized, and more expensive projects. Only 11% of data records indicated that monitoring was performed, and more expensive projects were more likely to be monitored. Standardization of monitoring and record keeping and dissemination of findings are urgently needed to ensure that dollars are well spent and restoration effectiveness is maximized. [source]