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1.
When fibrin polymerizes in a strong magnetic field, it can be highly oriented. The structural diffraction study of the oriented polymer becomes thus possible. The magnetic birefringence can also be used to study the development of the polymer Fibrinogen in solution is weakly oriented in high magnetic fields. In this work we present complementary results and discussion. The validity of the comparison of the orientation parameters of fibrinogen and fibrin with those of other orientable known biological structures is discussed. The orientation of fibrin formed from fibrin monomer solution is compared to that of fibrin formed by the action of thrombin on fibrinogen. The conditions to obtain highly oriented fibrin gels suitable for three dimensional structure studies are also briefly discussed. 相似文献
2.
The Murray River's 'Sea to Hume Dam' fish passage program: Progress to date and lessons learned 总被引:2,自引:0,他引:2
Since its commencement in 2001, a program to facilitate fish passage on a major stretch of Australia's longest river has installed eight structures, testing and modifying their design as they go. What are the results so far and what are the implications for future directions? 相似文献
3.
Three different fluorochrome and specific counterstain combination (DAPI/AMD, DA/DAPI and CMA/DA) treatments were applied to the chromosomes of four Microtidae (Rodentia) species. The results complete the data obtained in our previous paper (Burgos, M., Jiménez, R., & Dìaz de la Guardia, R., Genome 30:540–546, 1988) and prove that the changes in the constitutive heterochromatin in the evolution of the karyotypes of these species are not only due to gain or loss of heterochromatin, but are qualitative with respect to their nucleotide composition, repeated base pair organization or DNA-protein complex modification. These variations lead to the differential response to the fluorescence dye combinations used. 相似文献
4.
This paper studies a Non-convex State-dependent Linear Quadratic Regulator (NSLQR) problem, in which the control penalty weighting matrix in the performance index is state-dependent. A necessary and sufficient condition for the optimal solution is established with a rigorous proof by Euler-Lagrange Equation. It is found that the optimal solution of the NSLQR problem can be obtained by solving a Pseudo-Differential-Riccati-Equation (PDRE) simultaneously with the closed-loop system equation. A Comparison Theorem for the PDRE is given to facilitate solution methods for the PDRE. A linear time-variant system is employed as an example in simulation to verify the proposed optimal solution. As a non-trivial application, a goal pursuit process in psychology is modeled as a NSLQR problem and two typical goal pursuit behaviors found in human and animals are reproduced using different control weighting . It is found that these two behaviors save control energy and cause less stress over Conventional Control Behavior typified by the LQR control with a constant control weighting , in situations where only the goal discrepancy at the terminal time is of concern, such as in Marathon races and target hitting missions. 相似文献
5.
Heavy metal residues in birds of Lake Nakuru, Kenya 总被引:1,自引:0,他引:1
Jim K. Kairu 《African Journal of Ecology》1996,34(4):397-400
6.
Nine-banded armadillosDasypus novemcinctus Linnaeus, 1758 are interesting in part because (a) they give birth to litters of genetically identical quadruplets, and (b) the species’ range has expanded rapidly throughout the southern United States during the last 150 years, suggesting substantial dispersal of individuals. Using data from 7 field seasons between 1992 and 1999, we examined the extent of juvenile recruitment and retention of adults in a population of armadillos from northern Florida. There were no sex differences in the likelihood of recruitment or most attributes of male and female recruits at any age. In the few cases where more than one littermate was recruited into the population, siblings were significantly more widely dispersed as adults than they were as juveniles, thus limiting opportunities for interaction among clonal siblings. There was some evidence that recruits ranged more widely than other individuals, suggesting recruits may have been searching for suitable sites to establish themselves. Recruits were heavier than non-recruits as both juveniles and yearlings, which may have aided in establishing a home range, but recruits were lighter than other animals as adults. Overall, slightly less than 50% of armadillos first captured as adults were never seen in a subsequent year, suggesting these individuals may have been transients. However, some adults remained in the population for multiple years, moving very little from the area where they were first sighted. As with recruits, there were no sex differences in the likelihood of adults being retained in the population nor in the attributes of retained males and females. Retained animals exhibited more extensive anatomical damage and moved farther between successive sightings within years than did non-residents. Adults were more likely to be retained in the population than juveniles were to be recruited, and retained adults were older, heavier, and exhibited more extensive anatomical damage than did recruits. Our data seem to indicate a population characterized by limited recruitment of juveniles (particularly of clonemates) and an adult population exhibiting considerable turnover from year to year, but with a core of individuals who are long-term residents. 相似文献
7.
Jim Orford 《BMJ (Clinical research ed.)》1988,296(6624):729-730
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Physical and biological parameters that determine the fate of p-chlorophenol in laboratory test systems.
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Shake-flask and microcosm studies were conducted to determine the fate of para-chlorophenol (p-CP) in water and sediment systems and the role of sediment and nonsediment surfaces in the biodegradation process. Biodegradation of p-CP in estuarine water samples in shake flasks was slow over incubation periods of 300 h. The addition of detrital sediment resulted in immediate and rapid degradation evidenced by the production of 14CO2 from [14C]p-CP. The addition of sterile sediment, glass beads, or sand resulted in approximately four to six times more CO2 evolution than observed in the water alone. Densities of p-CP-degrading bacteria associated with the detrital sediment were 100 times greater than those enumerated in water. Bacteria in the water and associated with the sediment after preexposure of both water and sediment of p-CP demonstrated enhanced biodegradation. In some microcosms, p-CP was degraded completely in the top 1.0 cm of intact sediment beds. Sediment reworking activities by benthic invertebrates from one site were sufficient to mix p-CP deep into the sediment bed faster than biodegradation or molecular diffusion. p-CP was persistent at lower depths of the sediment, possibly a result of reduced oxygen conditions preventing aerobic biodegradation. 相似文献