Author Keywords: Rabbit; thermoregulation; infra-red; higher critical temperature 相似文献
In despite of the fruitful approach of Darwin, most of the brain scientists do prefer to analyze either one type of brain or even only one structure to interpret the brain function. The single neuron doctrine developed by Sherrington also did not consider these various aspects. The avenue opened by Hans Berger which introduced the analysis of the brain oscillations was an important step towards understanding of the “whole brain”.
In this report we aim to describe narratively, technical, strategical and philosophical steps to bridge “Sherrington Neuron Doctrine” with the “Neurons-Brain Theory” of the whole brain by means of the method developed by Hans Berger. 相似文献
In this paper we consider opposite problems connected with string non-inclusion relations: find the shortest string included in no string of a given finite language and find the longest string including no string of a given finite language. The predicate “string is not included in string β” is interpreted either as “ is not a subsequence of β” or as “ is not a substring of β”. The main purpose is to determine the complexity status of the non-similarity problems. Using graph approaches, we present NP-hardness proofs for the first interpretation and polynomial-time algorithms for the second one. Special cases of the problems, and related issues are discussed. 相似文献
In yeast cells harvested from aerobic growth, Zn-protoporphyrin accumulation inhibits respiratory activity and produces some letality. In yeast cells harvested from anaerobic growth this accumulation produces both a strong inhibition of cytochrome biosynthesis and of respiratory adaptation, accompanied by an important letality.
Zn-protoporphyrin is accumulated into the mitochondrial fraction and causes a total inhibition of O2 consumption by isolated mitochondria. The “in vitro” addition of purified Zn-protoporphyrin to intact mitochondria induces a lost of respiratory control. 相似文献
In heavily preirradiated cells, the T1 burst size is extremely small and multiplicity reactivation is considerably less extensive than in unirradiated cells. Presumably the survival of singly infecting T1 in these cells reflects absence of any type of repair. The observed phage sensitivity and shape of the curve are compatible with the expectation for completely repairless conditions. The mechanism underlying the minor recovery is not known; theoretical considerations make a phage REC repair mechanism seem likely. 相似文献
In this study the genotoxic activity of catecholestrogens and 16-hydroxy estrone has been investigated by performing Salmonella strain TA98 and TA100 Ames tests, sister chromatide exchange assays (SCE) and micronucleus assays on human peripheral lymphocytes (CBMN and ARA/CBMN). We found a lack of positive results with micronucleus assays, except for 2-hydroxy estradiol (2-OHE2), which shows a peculiar “bell shaped” trend of micronucleus number versus concentrations. SCE assay suggests weak genotoxic activity of all tested catechol metabolites, except 4-hydroxy estrone (4-OHE1), which also showed negative results by ARA/CBMN.
In this open debate, our results support the hypothesis of a weak genotoxicity, not correlated with the carcinogenetic potential of estrogens. 相似文献
1. 1.|An experiment was carried out to examine the effects of various levels of infra-red (i.r.) radiation on rectal temperature (RT) and respiration rate (RR) in New Zealand While rabbits.
2. 2.|A 4 × 3 × 6 factorial design was employed in which the factors were: four intensities of i.r. radiant heating of 0.0, 1.9, 2.1 and 2.4 MJ/m2/h, three replicates and six rabbits.
3. 3.|rectal temperature differed (P < 0.05) between treatments and were highest at the “high” level of i.r. radiation (1°C higher than for controls). At the “medium” and “low” levels of i.r. heating RTs were respectively 0.3 and 0.2°C higher than in controls.
4. 4.|At different levels of radiation RR were different (P < 0.05), with the highest (422.7 ± 218.1 breaths/min) at 2.4 MJ/m2/h i.r. radiant heating. This RR was almost 2.5 times that in controls, while at the “low” and “medium” i.r. levels RR values were respectively 1.5 and 2 times those of controls.
1. 1.The forearm of 5 female subjects ws thermally stimulated by 2 sets of interposed servo-thermodes that respectively drove skin temperature at ±0.1°C.s−1 for 25 s and then held it constant. Mean skin temperature remained constant. The sequence was repeated at adapting temperatures between 22.5 and 37.5°C.
2. 2.Thermal sensations, continuously reported by the position of a dial, were warmer for heterogeneous thermal stimuli than for homogeneous stimuli when mean skin temperature was greater than 30°C and cooler when less than 27.5°C.
3. 3.This phenomenon is inconsistent with a single additive contribution of “warm” and “cold” information to thermal sensations.
Author Keywords: Man; thermal sensation; skin temperature 相似文献
The bisexuality of Salix myrsinifolia is basically expressed through the development of a number of different forms of catkin that are intermediate between those that are entirely male and those that are entirely female. Flowers on bisexual catkins are fully developed, as on monosexual ones, but the male segment usually develops prior to the female one. With the exception of one form, a clear partitioning between the male and female parts of the catkin remains. This partitioning of the genders mainly takes place transversely, but in one case longitudinally. It is thus usually possible to speak of the division of a bisexual catkin into male and female sectors.
In all three populations studied in detail, marked shrubs, on which bisexuality had been noted at the beginning, retained this trait throughout the 9-year observation period. However, there were changes in both the expression of bisexuality, i.e. the frequency of bisexual and monosexual catkins, and in the frequency of different patterns of bisexual catkin. Only bisexual individuals with a clear prevalence of female features retained their character. In the two larger populations studied, many originally monosexual individuals became bisexual during the study period.
In the south-western part of the range of S. myrsinifolia in NE-Poland all local populations were characterized by the presence of bisexual individuals and are thus polygamous. There was a close association between the presence of S. myrsinifolia and the degree of ruderalization of habitats. The degree of polygamy in a population was also significantly correlated with ruderalization. It is concluded that androgyny and polygamy may be favoured not only by changes in environmental conditions, but also by the particular pressures to which individuals and populations of a species may be subject at the edge of its geographical range. 相似文献
1. 1. We propose a hierarchical model as a hypothesis to evaluate comfort in lighting environments.
2. 2. The model consists of physical quantities such as stimuli, and visual sensations as the first response, and then overall evaluation.
3. 3. A pilot experiment in a side-lit classroom usng 147 subjects was made to examine this model.
4. 4. It was found that in the side-lit classroom the most effective answers for discrimination between “acceptable” and “not acceptable” were “the surface of desk was not considered dark” and “not to experience any reflectance of lighting on the sheet of paper on which they wrote”.
5. 5. Moreover all of the effective items relate to the task area, namely desk and blackboard, and this meant that subjects gave priority to workability in the classroom.
Author Keywords: Daylighting; luminous environment; subjective experiment; class-room 相似文献
In order to detect trans-generational genomic instability, a total of 4806 metaphases from foetal tissues from the foetal offspring of X-irradiated female rats (5 Gy, acute dose) were analysed. The study's results showed that there is radiation-induced genomic instability: the number of aberrant metaphases and the breaks per total metaphases studied increased and were found to be statistically significant (p ≤ 0.05), with regard to the control group.
In order to identify how this trans-generational, radiation-induced chromosomal instability could influence the chromosomal behaviour of the offspring of irradiated rat females in front of a chemical agent (aphidicolin), a total of 2481 metaphases were studied. The observed results showed that there is an enhancement of the action of the chemical agent: chromosomal breaks per aberrant metaphases show significant differences (p ≤ 0.05) in the X-ray- and aphidicolin-treated group as regards the aphidicolin-treated group.
In conclusion, our findings indicate that there is trans-generational, radiation-induced chromosomal instability in the foetal cells from X-ray-treated female rats and that this RIGI enhances the chromosomal damage caused by the chemical agent aphidicolin. 相似文献
We suggest that the high variance observed is due neither to a constant attribute of the species like the photosynthetic CO2-carboxylase (in water plants with very high discrimination of the 13CO2 probably Rubisco) nor to the constant structural peculiarities of these species. Rather, it is likely due to the ‘diffusional resistance’ for the CO2-flux from the turbulent and/or fast flowing water, causing a very variable boundary layer on the plant surface. 相似文献
- 1. 1. Features of life history strategies of Antarctic terrestrial invertebrates are reviewed and compared with the predictions of two widely-used general life history models.
- 2. 2. Many features observed are consistent with the predictions of “adversity-” or “stress-selected” life histories, although “ruderal” characteristics are also observed.
- 3. 3. Many features are plesiotypic for the taxonomic groups concerned, suggesting a lack of evolved adaptations within the Antarctic biota.
- 4. 4. A large degree of flexibility is found in the life histories; this flexibility itself may allow passage of environmentally-imposed selective filters limiting colonisation and development in isolated and extreme terrestrial habitats.
- 5. 5. In general, Antarctic terrestrial invertebrates may be regarded as pre-adapted for survival of the various stresses imposed by their extreme environment.
The technique has been employed in the evaluation of mixed enzyme induction using phenobarbitone and β-naphthoflavone (benzoflavone). as a safe substitute for Aroclor-1254. The post-mitochondrial preparations from rats induced with the combined inducers had a similar “metabolic competence” to those derived from Aroclor induced animals. Such a combination would therefore provide a useful alternative to Aroclor-1254 for routine screening.
It was found that the level of “S9” present in the metabolic system greatly affected the quantitative mutagenic response. This varied considerably from chemical to chemical and underlined the need for such preliminary investigations in routine screening. 相似文献
Results (1) the relationship between circulating vitamin D3 and 25(OH)D in both groups was not linear, but appeared saturable and controlled; (2) optimal nutritional vitamin D status appeared to occur when molar ratios of circulating vitamin D3 and 25(OH)D exceeded 0.3; at this point, the Vmax of the 25-hydroxylase appeared to be achieved. This was achieved when circulating 25(OH)D exceeded 100 nmol.
We hypothesize that as humans live today, the 25-hydroxylase operates well below its Vmax because of chronic substrate deficiency, namely vitamin D3. When humans are sun (or dietary) replete, the vitamin D endocrine system will function in a fashion as do these other steroid synthetic pathways, not limited by substrate. Thus, the relationship between circulating vitamin D and 25(OH)D may represent what “normal” vitamin D status should be. 相似文献