Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Approximation properties of Ibragimov-Gadjiev-Durrmeyer operators on Lp (R+)

100%

Ulusoy G. , Aral A.

2017

tom Vol. 50, nr 1

156--174

We deal with the approximation properties of a new class of positive linear Durrmeyer type operators which offer a reconstruction of integral type operators including well known Durrmeyer operators. This reconstruction allows us to investigate approximation properties of the Durrmeyer operators at the same time. It is first shown that these operators are a positive approximation process in Lp (R+). While we are showing this property of the operators we consider the Ditzian-Totik modulus of smoothness and corresponding K-functional. Then, weighted norm convergence, whose proof is based on Korovkin type theorem on Lp (R+), is given. At the end of the paper we show several examples of classical sequences that can be obtained from the Ibragimov-Gadjiev-Durrmeyer operators.

Investigation of the potential correlation between the cognitive status and the levels of brain fatty acids in young and aged C57BL/6 mice

80%

Jakubowska-Dogru E. , Yetimler B. , Ulusoy G. , Celik T.

nr S

The aim of the present study was to investigate the possible relationship between the levels of various brain fatty acids and learning indices in aged (22-23 months old) and young (2-3 months old) female C57BL/6 mice classified as “good” or “poor” learners basing on their performance in a spatial learning task: the Morris water-maze. The levels of several fatty acids including palmitic, stearic, oleic, linoleic, arachidonic (AA), and docosahexaenoic acid (DHA) were measured by gas chromatography in brain tissue samples from four different brain areas: hippocampus, cortex, striatum and hypothalamus. The results of behavioural tests confirmed a decline in learning skills with age. However, a great individual variation was revealed in learning scores between aged subjects indicating that biological aging is not always parallel to chronological aging. The relative levels of palmitic, stearic, oleic, linoleic, arachidonic, and DHA acids in the four examined brain structures were very similar. Interestingly, except hypothalamus, no significant relation has been found between the brain levels of DHA omega-3 acid and the animal’s age or cognitive status. This finding contributes to the current debate on the value of DHA supplementation as an effective protective treatment against aging and dementia. The only significant correlation between learning performance and the brain fatty acid levels was found for arachidonic acid in the young mice hippocampus, structure known to be critical for spatial learning and memory. AA level was significantly lower in young “good learners” as compared to both young “poor learners” and old “good learners” with young “good learners” showing significantly better performance than the two other groups. These results are discussed in the context of recent reports about elevated AA levels in Alzheimer’s dementia.