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51.
This paper examines whether the relationships between a number of characteristic limnological variables (suspended particulate matter, turbidity, Secchi depth, light attenuation, and chlorophyll a) determined for temperate lakes are consistent with the relationships found in Mediterranean lakes such as Lake Kinneret. We found that the use of published relationships between lake variables may lead to erroneous results when applied indiscriminately to other lake types.  相似文献   
52.
Borisover M  Laor Y  Bukhanovsky N  Saadi I 《Chemosphere》2006,65(11):1925-1934
Using fluorescence intensity measurements, pyrene interactions with different types of effluent dissolved organic matter (EDOM) originated from treated municipal wastewater are examined. Multiple observations show that fluorescence intensity of pyrene–EDOM solutions is non-linearly related to pyrene concentration, with distinct concave-up dependence. Testing the effect of pyrene concentration on fluorescence intensity of pyrene–EDOM solutions provides a tool to examine whether binding of an organic compound to EDOM follows linear or non-linear isotherm. Possible coupling between static and dynamic quenching effects was addressed while analyzing fluorescence data. Limited number of EDOM binding sites results in a non-linear binding isotherm such that the concept of pyrene “partitioning” between aqueous phase and “bulky” EDOM organic phase is hardly relevant. Maximal EDOM capacity for pyrene binding is estimated approximately as 0.1% w w−1. Examination of the differences between the total fluorescence intensity of pyrene–EDOM solution and the fluorescence intensities of separated constituents (pyrene and EDOM) was used to illustrate the accumulation of pyrene–EDOM complexes and saturation of some EDOM binding sites. Strong interactions between pyrene and EDOM binding sites may result in pyrene distribution coefficients differing at least by a factor 3.5–7 at varying pyrene concentrations.  相似文献   
53.
More than 10 years after a chromosomal anomaly screening programme was set up in France for pregnant women of advanced age, amniocentesis is still a controversial issue. The reasons why eligible women did not utilize the test and whether or not the existence of social welfare coverage determined women's access to prenatal diagnosis were studied. A group of 291 women aged ⩾35 years who recently gave birth to normal liveborns was interviewed by telephone. Among those aged 38 years and over, who automatically qualified for social security coverage, 75 per cent had undergone amniocentesis as opposed to 23 per cent in the 35 to 37-year-old non-covered age group who did not qualify for social security coverage. In both groups, access to amniocentesis was found to depend on the physicians', women's and male partners' attitudes towards prenatal diagnosis and abortion. Among the younger group, the uptake depended mainly on socio-economic factors. Institutional policies should ensure greater equality of access while allowing for individual preferences.  相似文献   
54.
Summary Seothyra henscheli (Eresidae) is a burrowing spider that lives in the dune sea of the southern Namib Desert, Namibia. Prey capture by these spiders involves a foray from a cool subterranean retreat to the undersurface of a capture web that can be lethally hot. Striking, disentangling and retrieving prey from the capture web typically involves several short trips to the capture web, alternating with retreats to the cool burrow. It has been suggested that this behavior limits the increase of body temperature a spider must experience while working at the hot capture web. We used biophysical models in conjunction with direct observations of prey-capture behavior and distributions of sand temperature to estimate body temperatures experienced by S. henscheli during prey capture. In the circumstances we observed, only the relatively long post-strike retreat from the capture web is important in keeping spiders' body temperatures from exceeding their lethal limits. After the post-strike retreat, shuttling appreciably limits the increase in body temperature of small individuals, but may have little effect on body temperature increase in larger spiders. Correspondence to: J.S. Turner at the present address  相似文献   
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