We investigated the fate of the drug ivermectin in the soil. We found that ivermectin was transformed solely by photos, leading to the formation of two ivermectin isomers. We indeed failed to detect any biotransformation reaction of the chemical either in the soil or in fungal liquid cultures. According to its limited water solubility, the bioavailability of ivermectin was very low in the soil solution. Here, we show that ivermectin, transferred to the soil from faeces of drug-treated cattle, could be stored for long periods in the soil. 相似文献
Summary Deer mice (Peromyscus maniculatus), kept in individual cages under constant dim-light conditions, displayed steady free-running rhythms of activity, the period of which varied between individuals.When two previously isolated mice with different rhythms were placed in a common enclosure, under the same constant light conditions, they soon displayed a mutual synchronization of their activity rhythms. When separated again, the mice lost mutual synchronization (Figs. 1 and 2)The process by which mutual synchronization was attained in the common enclosure is typical of entrainment by an external synchronizer (Zeitgeber). Our results suggest that the activity rhythm of the dominant mouse entrains the activity rhythm of the subordinate, and is thus a social Zeitgeber. 相似文献
The evolution of multiple sexual traits remains controversial and poorly understood in evolutionary biology. In many bird species, males exhibit complex courtships involving feather ornaments and behavioral display. Multiple traits may convey information on the genetic and phenotypic quality of males. In particular, fixed characters, such as feather ornaments (produced once a year during the annual molt in many bird species) might convey information about past male condition (at the time of trait development); whereas flexible traits such as behavioral displays should be sensitive to present condition. Here we show that both flexible behavioral displays and fixed feather ornaments of peacocks, used by females to choose a mate, honestly reflect health status. Correlative data showed that peacocks with high display rate (the number of behavioral displays per hour) and a large number of tail eyespots had low levels of circulating heterophils, suggesting better health status. Experimental activation of the immune system, through LPS injection, significantly reduced display rate compared to a control group. However, the sensitivity of a male display rate to the immune challenge was dependent on the number of tail eyespots: males with higher number of tail eyespots were better able to cope with the experimental immune challenge, and maintained their display rate at levels closer to the levels performed before the immune activation. These results are consistent with the idea that multiple signaling might enhance information reliability. 相似文献
In-situ bioremediation is a process by which contaminants in subsurface environments are biologically eliminated or mineralized; however, it is often difficult to implement. Microbes sparsely distributed in deep soils are incapable of degrading a chemical rapidly; furthermore, fine-pore structures of soils tend to retard the penetration and propagation of these microbes and hinder oxygen transfer. The latter is particularly detrimental to the aerobic growth of microbes, which is often essential for bioremediation. Measures intended to promote bioremediation, such as the addition of surfactants for enhancing dissolution and the application of genetically engineered microbes for accelerating the biodegradation of contaminants, are almost impossible to adopt. This is attributable to the fact that various facets of the bioremediation process (e.g., the distribution of dissolved contaminants, nutrients, and oxygen, and the concentration of microbes) cannot be readily manipulated. This article proposes a novel technology, namely, bio-wall. This technology resorts to an in-situ constructed medium with porosity and organic content greater than those of the original soil for promoting the adsorption and retention of microbes and the biodegradation of contaminants. Moreover, oxygen and nutrients are supplied to the bio-wall to facilitate microbialgrowth. The results of conceptual design study and simulation have revealed that the technology is indeed feasible and, under certain environmental conditions, cost-effective. Particularly noteworthy is the fact that bio-wall can prevent contaminant migration through the enhancement of the biodegradation rate and reduction of the plume-distance, both by several orders of magnitude. 相似文献
Background: discussions with occupational physicians and a postal survey identified the shortcomings of previous programs, mainly found in the fields of occupational hygiene, ergonomics, environmental health and management.Objectives of the new program: basic knowledge (see content), the development of problem solving skills, scientific and social attitudes.Content: first year: occupational health practice, occupational hygiene, epidemiology, work physiology, toxicokinetics and dynamics and in service training (4 weeks). Second year: occupational pathology, environmental health, ergonomics, social legislation, safety, management and in service training (4 weeks). The total study load is estimated at about 1600 hours per year.Methods: interactivity is stimulated by the introduction of interdisciplinary seminars, project work in groups and Socratic dialogue. The objectives, contents and teaching and student-evaluation methods of the separate items were defined before selecting teachers.Finality of the program: a masters title sufficient to practice occupational medicine in Belgium. A subsequent postacademic training of 2 years, while at work, will be required for the title of specialist in occupational medicine, valid at European Union (EU) level. It will include preparing and publically defending a thesis.Statement: The collaboration of ex-students working in the field is essential in the development and quality assessment of adequate teaching programs. 相似文献
This is the second of three articles prepared to explain the Teller County growth management process. As part of an ongoing
growth management process in Teller County, Colorado, opportunities and constraints for development and conservation were
identified. The scenic mountain county faces a number of issues because of growth. The recognition of those issues has resulted
in the goal to direct future growth to the most appropriate and cost-effective places. To determine those places that are
best for new development, thorough ecological inventories were conducted for the entire county as well as for the City of
Woodland Park area. From these inventories, environmentally sensitive areas were identified. The environmentally sensitive
areas were considered constraints in conducting suitability analyses for a variety of potential land uses. The suitability
analyses resulted in the identification of opportunities for future growth in Teller County generally as well as the more
specific Woodland Park planning area. This article, like the other two, is part of a reflective analysis by the planners who
were involved.
Paper 2 in a series 3. 相似文献
Objective: We compared the differences in the braking response to vehicle collision between an active human emergency braking (control condition) and cruise control (CC) or adaptive cruise control (ACC).
Methods: In 11 male subjects, age 22 to 67 years, we measured the active emergency braking response during manual driving using the accelerator pedal (control condition) or in condition mimicking CC or ACC. In both conditions, we measured the brake reaction time (BRT), delay to produce the peak braking force (PBD), total emergency braking response (BRT + PBD), and peak braking force (PBF). Electromyograms of leg and thigh muscles were recorded during braking. The tonic vibratory response (TVR), Hoffman reflex (HR), and M-waves were recorded in leg muscles to explore the change in sensorimotor control.
Results: No difference in PBF, TVR amplitude, HR latency, and Hmax/Mmax ratio were found between the control and CC/ACC conditions. On the other hand, BRT and PBD were significantly lengthened in the CC/ACC condition (240 ± 13 ms and 704 ± 70 ms, respectively) compared to control (183 ± 7 ms and 568 ± 36 ms, respectively). BRT increased with the age of participants and the driving experience shortened PBD and increased PBF.
Conclusions: In male subjects, driving in a CC/ACC condition significantly delays the active emergency braking response to vehicle collision. This could result from higher amplitude of leg motion in the CC/ACC condition and/or by the age-related changes in motor control. Car and truck drivers must take account of the significant increase in the braking distance in a CC/ACC condition. 相似文献