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261.
In order to determine the effect of drag reducing polymers on the occurrence of atherosclerosis, the Guinea pigs were used as the experimental animals. The inhibitory effect of a drag reducing polymer (polyacrylamide) on atherosclerosis in the aortas of Guinea pigs on a high cholesterol diet (2%) was investigated over a period of 6 months. The aortas, livers, kidneys and lungs of the animals, which were separated into four experimental groups (control, polymer, cholesterol and cholesterol + polymer) were also investigated both macroscopically and light microscopically. The selected physiological parameters such as, plasma cholesterol levels, plasma hemoglobin, hematocrit and total lipid values were determined at regular intervals for each group. The results indicate that the atherosclerosis in aorta of the animals receiving the polymer injection is suppressed significantly and the drag reducing water soluble polymers may be effectively applied against atherosclerosis. 相似文献
262.
263.
Two methods of measuring the electrical conductivity of the dried collodion membrane in contact with an electrolyte solution are described and the results of such measurements with different electrolytes in different ranges of concentration recorded. Some of the difficulties encountered in making these measurements are outlined. Of special interest was the fact that each membrane with each electrolyte showed a maximum level of resistance at a certain point in the dilution scale, a level which was not surpassed by further dilution. It is believed that this level was fixed by the collodion itself rather than by the contiguous electrolyte solution. Its existence limited the results available for reasonable interpretation. In relatively concentrated solutions the conductivity was shown to be approximately proportional to the concentration. With different electrolytes in the same concentration it was shown that the conductivities varied much more than in simple solutions without a membrane and that they fell in the order HCl > KCl > NaCl > LiCl. A method was described whereby the electrolyte content of a membrane in contact with different chloride solutions could be determined. It was shown that a membrane saturated with either 0.5 N HCl or 0.5 N KCl had practically the same total electrolyte content whereas the same membrane in contact with 0.5 N LiCl contained only half the quantity. These results were used in interpreting the conductivity data, the evidence presented strongly suggesting that two factors are operative in causing the widely divergent conductivities recorded with different electrolytes. The first factor depended on the quantity of electrolyte which can enter the membrane pores, a quantity dependent on the size of the pores and the volume of the larger of the two hydrated ions of the electrolyte. This factor was the chief one in determining the difference in conductivity between KCl and LiCl. The second factor was concerned with differences in the mobility of the various cations within the membrane brought about by friction between the moving ions and the pore walls. With KCl and HCl the quantity of electrolytes entering the membrane was in each case the same, being determined by the size of the larger Cl- ion. The widely different conductivity values were explained as due to the changes in the mobility of the two cations within the membrane pores. 相似文献
264.
265.
The structural characteristics, unique features, various organ measurements of males and females of the Sperchon (Scutosperchon) akdagensis sp. n. water mite from Turkey are described. In addition, morphological characteristics of the new species are compared with
related species. 相似文献
266.
Sibel Özbudun Demirer 《Dialectical Anthropology》2011,35(1):111-129
Although the presence of anthropology is strongly felt during the first decades of the Turkish republican history, namely
the period between 1923 and 1940, it is striking to see that the discipline was conceived more as a nation-building device
than a scientific endeavour. This article traces the formation of Turkish anthropology from the late Ottoman period to the
consolidation of the Republican regime, emphasizing the interesting oscillations between physical and social/cultural anthropologies,
which are alternately brought to fore according to the requirements the political agenda. 相似文献
267.
Chloroform concentrations were observed and input and output fluxes estimated over a 2-yr period in a small coniferous catchment
(0.22 km2) in southeast Sweden. Water discharge was measured daily, and runoff water was sampled bi-weekly for chloroform analysis.
An approximate chloroform budget was calculated, which indicated that the annual output of 6 μg m−2 yr−1 was approximately six times higher than the input, inferring an internal source of chloroform in the catchment. To the best
of our knowledge, neither flux estimates nor mass balances have previously been made for chloroform on a catchment scale,
nor have data regarding natural runoff variation with time been gathered. Concentrations of chloroform in runoff were found
to be generally high during wet periods, such as spring, but also peaked during summer rain events. The observed pattern suggests
that chloroform is formed in surface soil layers and transported to the outlet under high-flow conditions and during dry-period
rain events; it is lost through degradation or evaporation during drier periods due to longer soil water residence times.
The data suggest that the variation among replicates increases with concentration; this emphasizes the need to know what the
degree of on-site variation is, so one can collect a sufficient number of replicates to permit detection of spatial or temporal
changes. 相似文献
268.
Background
Ion transport proteins generate small electric fields that can induce directional cell motility; however, little is known about their mechanisms that lead to directedness. We investigated Na, K-ATPase (NaKA) and Na+/H+ exchanger isoforms (NHE1 and 3) in SaOS-2 and Calvarial osteoblasts, which present anode- and cathode- directed motility, during electrotaxis. 相似文献269.
We address the issue of analyzing electroencephalogram (EEG) from seizure patients in order to test, model and determine the
statistical properties that distinguish between EEG states (interictal, pre-ictal, ictal) by introducing a new class of time
series analysis methods. In the present study: firstly, we employ statistical methods to determine the non-stationary behavior
of focal interictal epileptiform series within very short time intervals; secondly, for such intervals that are deemed non-stationary
we suggest the concept of Autoregressive Integrated Moving Average (ARIMA) process modelling, well known in time series analysis.
We finally address the queries of causal relationships between epileptic states and between brain areas during epileptiform
activity. We estimate the interaction between different EEG series (channels) in short time intervals by performing Granger-causality
analysis and also estimate such interaction in long time intervals by employing Cointegration analysis, both analysis methods
are well-known in econometrics. Here we find: first, that the causal relationship between neuronal assemblies can be identified
according to the duration and the direction of their possible mutual influences; second, that although the estimated bidirectional
causality in short time intervals yields that the neuronal ensembles positively affect each other, in long time intervals
neither of them is affected (increasing amplitudes) from this relationship. Moreover, Cointegration analysis of the EEG series
enables us to identify whether there is a causal link from the interictal state to ictal state. 相似文献
270.
Hasan Meydan Mehmet A Yildiz Fulya Özdil Yasemin Gedik Ceyhan Özbeyaz 《Acta veterinaria Scandinavica》2009,51(1):5