Competencies: a cure for pre-med curriculum     

Anderson WA  Amasino RM  Ares M  Banerjee U  Bartel B  Corces VG  Drennan CL  Elgin SC  Epstein IR  Fanning E  Guillette LJ  Handelsman J  Hatfull GF  Hoy RR  Kelley D  Leinwand LA  Losick R  Lu Y  Lynn DG  Neuhauser C  O'Dowd DK  Olivera T  Pevzner P  Richards-Kortum RR  Rine J  Sah RL  Strobel SA  Walker GC  Walt DR  Warner IM  Wessler S  Willard HF  Zare RN 《Science (New York, N.Y.)》2011,334(6057):760-761

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Contrasting Observation and Transect-Based Models of Cattle Distribution on Lincoln National Forest,New Mexico     

Heather Halbritter  Louis C. Bender 《Strength and Conditioning Journal》2011,64(5):514-520

Perceptions of cattle distribution and resource conflicts are often based upon qualitative observations of cattle by managers or the general public. Such information on cattle presence and inferred habitat preferences may not reflect true habitat correlates of cattle because observations do not include any sampling design. We documented cattle presence and used presence data to model distribution of cattle with respect to landscape features on the Lincoln National Forest (LNF) of south-central New Mexico, an area of conflict with regard to cattle herbivory. We recorded cattle presence both from visual observations of cattle while conducting other research activities and from randomized pellet-group transects during the spring–autumn period when cattle grazed the high-elevation habitats. Distribution of cattle differed for several habitat variables between datasets, although distribution models from both datasets indicated that elevation, slope, distance to water and roads, and vegetation cover type most influenced cattle presence. Cattle presence was associated with a variety of cover types, and cattle were generally within 500 m of water and on slopes of < 15–20%. Observation-based models showed positive associations with open cover types, including the strongest positive association with montane meadows, the area of conflict in LNF. In contrast, transect-based models showed positive associations with more cover types (11) than did observation-based (6). Observation-based models also showed higher association with areas closer to roads. Inferred habitat preferences based on casual observations of cattle may not accurately reflect true distribution or use, as transect-based models predicted much broader distribution throughout LNF and higher overall probabilities of cattle presence. Because cattle distribution included many other vegetation cover types in addition to montane meadows, management to enhance positive correlates of cattle distribution on LNF may be useful to alter cattle distribution away from areas of perceived conflict.  相似文献   

Lamellodiscus (Monogenea: Diplectanidae) parasites of Dentex macrophthalmus (Teleostei: Sparidae) from the North Atlantic coast of Africa, with a redescription of L. dentexi Aljoshkina, 1984, and description of three new species     

Diamanka A  Neifar L  Pariselle A  Euzet L 《Folia parasitologica》2011,58(1):17-26

Lamellodiscus dentexi Aljoshkina, 1984, a gill parasite of Dentex macrophthalmus (Bloch), is redescribed based on new material from the northwest coast of Africa (Senegal and Morocco). Three new species of Lamellodiscus Johnston et Tiegs, 1922 from D. macrophthalmus are described, Lamellodiscus toguebayei sp. n., L. vicinus sp. n., and L. triacies sp. n., all belonging to the "ignoratus" group. They can be distinguished from all other species of this group by the size and shape of male copulatory organ and sclerotised parts of the haptor. Considering the peculiar morphology of the male copulatory organ (long and thin tube) we propose to put together L. dentexi, L. virgula Euzet et Oliver, 1967 and L. obeliae Oliver, 1973 to form the "elongatus" type within the "elegans" group.  相似文献   

Predicted and observed finger diameters in field soils     

Coen J. Ritsema  Tammo S. Steenhuis  J. -Yves Parlange  Louis W. Dekker 《Geoderma》1996,70(2-4):185-196

Wetting front instability resulting in fingered flow has been found in both wettable and nonwettable soils. Understanding how and when this phenomenon occurs under field conditions is greatly limited. Laboratory research has resulted in a number of expressions for finger diameter. In this paper we test the applicability of one of these equations for three different soils in the Netherlands where detailed soil sampling of moisture content was done earlier. In addition, information needed for finger prediction, such as the main wetting and drying loops of the soil moisture characteristic curves and the unsaturated and saturated soil conductivities, were measured in the laboratory. Results show that predicted finger diameters for the two sandy soils agreed well with the observed moisture patterns, while for the loess soil the wetting front was flat as predicted. The finger diameters in dry soil were based on the main wetting loop and in the wet soils were dependent on the main drying loop.  相似文献   

Stepwise thermal analysis technique for estimating mercury phases in soils and sediments     

Louis M. Azzaria  Alijan Aftabi 《Water, air, and soil pollution》1991,56(1):203-217

Traces of H4 phases in soils, sediments and mineral standards were determined by thermal analysis at successively higher temperature steps. Mercury was liberated at each step, concentrated on Au, then determined by flameless atomic absorption. Some Hq determinations were made by liberating the element by continuous heating at the rate of 20 and 100°C min^?1. Soil samples were collected from the vicinity of a Hg mine, a Cu deposit and fault zones. Sediment samples were collected near a H9 roasting plant, a chlor-alkali plant and a Cu smelter. The results show that, for all the samples, most of the Hg is liberated during the 200°C temperature step. Some samples show thermal release characteristics similar to those of a. cinnabar-quartz mixture. Other samples show characteristics possibly related to sorbed elemental Hg. The results show that stepwise compared to continuous heating gives more resolution and thus may prove to be easier in estimating traces of Hg phases in soils and sediments.  相似文献   

Volatile emissions of navel oranges as predictors of freeze damage     

Obenland DM  Aung LH  Bridges DL  Mackey BE 《Journal of agricultural and food chemistry》2003,51(11):3367-3371

Volatile emissions of navel orange (Citrus sinensis L. Osbeck cv. Washington) fruit were evaluated as a means for predicting and gauging freeze damage. The fruits were subjected to -5 or -7 degrees C treatments in a laboratory freezer for various time periods of 2-9.5 h and stored at 23 degrees C for 1, 2, or 7 days, after which time the emission of volatiles from the fruit was measured. Following the final day of volatile measurements the fruits were stored at 5 degrees C for an additional 2-3 weeks and then evaluated for fruit quality characteristics. Peel injury in the form of brown lesions, drying of the juice vesicles, a decline in acidity, and a loss of flavor were observed to occur as a result of freezing. Corresponding to the loss in fruit quality were large increases in the emissions of ethanol, ethyl butanoate, methyl hexanoate, and ethyl octanoate. With the exception of methyl hexanoate, for which volatile emissions decreased during storage for 7 days at 23 degrees C, all of the other volatiles were relatively unchanged in amount by storage. Treatment at -7 degrees C caused greater injury, quality loss, and more volatile emanation than did freezing at -5 degrees C. The measurement of volatile emissions appears to be a useful approach to identify freeze-damaged navel oranges.  相似文献   

Application of para-nitrophenol (pNP) enzyme assays in degraded tropical soils     

Louis V. Verchot  Teresa Borelli 《Soil biology & biochemistry》2005,37(4):625-633

Enzyme activities have been used as indicators of soil quality and changes in biogeochemical function due to management or perturbations. The objective of this study was to answer a number of methodological questions regarding sampling schemes, sample handling recommendations, and assay procedures to facilitate the use of enzyme assays in the tropical highlands of East Africa. We used para-nitrophenol (pNP) based substrates for five enzymes: β-glucosidase, cellobiohydrolase, chitinase, acid phosphatase, and alkaline phosphatase. In the first experiment, we examined sampling procedures and compared the results of determining enzyme activities on a plot using composite or discrete samples. Composite samples usually had higher activities than the means of individual cores (P<0.05), but relative ranking of sites was the same if analyses were based on composite or discrete samples. In the second experiment, we examined the effects of storage time and conditions on enzyme activity. Enzyme activity degraded rapidly in frozen samples, but was better maintained in samples stored at 4 °C. Phosphatase and cellobiohydrolase activity declined after 14 days of storage, while the activity of the other enzymes remained close to the values of fresh samples for 28 or more days. In the third experiment, we examined the effect of the addition of an antiseptic, toluene, to prevent bacterial growth during the assay. We found no consistent toluene effect (P>0.4), probably because the assays were of short duration and microbial growth was minimized. Finally, we looked at the incubation time necessary to produce reliable results. Phosphatases, with relatively high activities could reliably be determined in 2 h incubations, but the other enzymes had much lower activities and required longer incubation times for reliable determination. For the enzymes we looked at, 4 h was a good standard time for determining the activity of even the lowest activity enzymes. The results of this study provide practical guidelines for applying these enzyme assays in the degraded tropical soils.  相似文献   

Supplementation of Commercial Feeds with Beef Liver for Indoor Nursery Culture of Freshwater Prawns Macrobrachiurn rosenbergii     

Rosa E.  Molina-Vozzo  John M.  Heinen Louis R.  D'Abramo 《Journal of the World Aquaculture Society》1995,26(1):103-106

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Species diversity: Concept,measurement, and response to clearcutting and site-preparation     

Benee F. Swindel  Louis F. Conde  Joel E. Smith 《Forest Ecology and Management》1984,8(1):11-22

A review of aspects of diversity recently introduced in the statistical literature by Patil and Tallie is given: species diversity as an average property of a community is defined; the property averaged is identified as species rarity; and relations between common indices of diversity and associated measures of rarity are illuminated. This paper also computes common indices of diversity from substantial empirical data collected before clearcutting and site-preparation under two management regimes and for 3 years following planting of slash pine (Pinus elliottii) to illustrate that the initial response to these forest operations is increased species diversity, i.e., increased species rarity. This response may be expected whenever clearcutting and site preparation reduces but does not eliminate previously abundant, late-successional species and permits the reappearance of early-successional species, including forbs and grasses.  相似文献   

Libri novi     

Louis Genevois 《Plant foods for human nutrition (Dordrecht, Netherlands)》1970,19(4):385-386

Ohne Zusammenfassung  相似文献