The function of adult neurogenesis in the dentate gyrus is not yet completely understood, though many competing theories have attempted to explain the function of these newly -generated neurons. Most theories give adult neurogenesis a role in aiding known hippocampal/dentate gyrus functions. Other theories offer a novel role for these new cells based on their unique physiological qualities, such as their low excitability threshold. Many behavioral tests have been used to test these theories, but results have been inconsistent and often contradictory. Substantial variability in tests and protocols may be at least partially responsible for the mixed results. On the other hand, conflicting results arising from the same tests can serve as aids in elucidating the function of adult neurogenesis. Here, we offer a hypothesis that considers the cognitive nature of tasks commonly used to assess the function of adult neurogenesis, and introduce a dichotomy between tasks focused on discrimination vs. generalization. We view these two aspects as opposite ends of the continuous spectrum onto which traditional tests can be mapped. We propose that high neurogenesis favors behavioral discrimination while low adult neurogenesis favors behavioral generalization of a knowledge or rule. Since many tasks require both, the effects of neurogenesis could be cancelled out in many cases. Although speculative, we hope that our view presents an interesting and testable hypothesis of the effect of adult neurogenesis in traditional behavioral tasks. We conclude that new, carefully designed behavioral tests may be necessary to reach a final consensus on the role of adult neurogenesis in behavior., A. Pistikova, H. Brozka, A. Stuchlik., and Obsahuje bibliografii
Purification of quartz using an environment-friendly method is important in the contaminants removal. This paper presents advanced method based on calcination pretreatment combined with ultrasound-assisted leaching, for removing iron impurities from industrial quartz. The solvent used is a mixture comprised by diluted hydrochloric acid and oxalic acid. The effects of experimental parameters were investigated and the purification mechanism was discussed using particle size analyzer, scanning electron microscope and polarized light microscope. SiO2 content of concentrate could be increased from 99.6828% to 99.9047%, which achieved 3N level high purity quartz, and Fe2O3 content reduced from 0.0857% to 0.0223%, under the optimal conditions, i.e., calcination temperature of 900 °C, holding time of 2 h, oxalic acid concentration of 10 g/L, hydrochloric acid concentration of 5%, liquid solid ratio of 5, leaching temperature of 60 °C, ultrasound power of 400 W and treatment time of 30 min. Compared to conventional method, the proposed method significantly accelerates the leaching process and increases the iron removal rate. At the same time, the method also can remove gas-liquid inclusions. and Yang Changqiao, Li Suqin, Bai Jiaxing, Han Shuaishuai.
The article deals with the use of different types of connectors in the adversative complex phrases in Old Church Slavonic and their Greek parallels. The most common and most frequent conjuntions are a, nž, and to a certain extent obače, whereas the particle že is mostly defined as adversative by the semantics of the clauses. In some manuscripts from the 18th and 19th centuries appart from the use of no and a, examples of adversative sentences with the conjuctions ami and tuku are frequent, which are common also in Standard Macedonian (but ami mostly in dialects). The conjuction tuku has developed from the adverb tolku and the conjunction ami is taken from the Greek vernacular ami. The use of conjunctions from other languages - ami from Greek and ama from Turkish which had a significant influence on the spoken (Slavic) language in Macedonia vis-à-vis the language used in the Old Church Slavonic manuscripts shows that it was common to accept a foreign language construction. However, it should be mentioned that both conjunctions in Standard Macedonian are used as a kind of stylistic specifity, usually in colloquial style. The development and use of new conjunctions could also be explained by the phonemic characteristic of the conjuntion nž, to lose the nasal and thus to become not expressive enough as adversative.