Step-down tests

Several studies have looked at the effects of combined preparations that include ginseng. A preparation of Biota orientalis, Panax ginseng, and Schisandra chinensis (S-113 m) improved memory retention in a passive-avoidance task with senescence-accelerated mice (Nishiyama et al. 1996). This combination also reduced memory impairments induced by ethanol and scopolamine in the step-down test and electroconvulsive shock-induced memory impairment (Nishiyama et al. 1995). 

In this section we focus on hypothesis testing and discuss both individual and simultaneous tests for detecting nonzero effects. Of special interest are the step-down tests described in Section 5.2, as these offer improved power over single-step tests. 

DRUG % Motile Cells test Swim Rate Test % Step-up Test % Step-down test O2 Uptake in Dark... 

Equation (11) is model independent and provides the means for determining the unknown volume of the system. The question arises in practice whether t can be evaluated accurately from eq. (11). Small errors in the tracer mass balance, eq. (7), can lead to large errors in t and even larger errors in the estimation of the variance of the E curve (43). Due to the relationship of E(t) and F(t) the mean residence time can also be obtained directly from a step-up or a step-down test ... 

Determination from the step-down test is the most accurate (43). 

J) Source side resistance R (to control the p.f. as per the test requirements) High current step down transformer Test object (j Current shunt (2) R-C voltage dividers (12) Recording instruments ... 

Step through (ST) and step down (SD) tests were performed using 5-week-old male ddY mice according to the method employed in our laboratory [9]. They were used in the experiments after 1 week acclimation to the environment. 

A Hie latency which indicated the time mice entered the dark compartment in ST test. B Mice which did not enter the dark compartment within 300 s were termed successful mice. C The number of errors was the number of times of stepping down to the floor in SD test. D The number of mice which made no errors in SD test. p < 0.05. p < 0.01 vs. control group +p < 0.05 vs. ethanol group in Mann-Whitney s Utest. Mean + SEM. n=12. 

The laser flash method has been used by Foreman36 and by Agari et al60, the latter considering the effect of test conditions and sample size on accuracy. Papa et al61 developed a prototype apparatus that operated with step-down temperature perturbations and could be used with molten samples. 

A method of this form is called a stepdown test because it steps down from the most statistically significant to the least statistically significant. 

Alcohol extract from saffron has been also examined for learning and memory, in step through (ST) and step down (SD) tests, in normal and in leaming-and memory-impaired mice. The results showed that this extract ameliorates the impairment effects of ethanol on learning and memory processes and possesses a sedative effect [85-87]. In addition, recent experiments have shown that crocin and crocetin derivatives inhibit promotion of tumor in mice [88]. 

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