Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 6
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

Telomeres are repetitive sequence structures at the ends of chromosomes. They consist of the double stranded DNA repeats followed by the short single stranded DNA. In humans and other verterbrates the telomeric sequence is composed of tandem of TTAGGG repeats. With each cells division telomeres shorten by up to 200 base pairs. Telomerase is an enzyme responsible for continuous cell growth and is repressed in most somatic cells, except proliferating progenitor cells, but in more than 85% of cancer cells telomerase expression is observed. Tumour cells with metastatic potential may demonstrate a high telomerase activity, allowing cells to escape from the inhibition of cell proliferation due to shortened telomeres. Determination of telomerase expres- sion was performed with the use of PCR ELISA in samples isolated from bovine leukaemia virus (BLV) infected cows. Telomerase activity was found in almost all investigated samples. The relative telomerase activity (RTA) was higher in infected cows than in healthy animals and the differences were statistically significant (α=0.05). In blood lymphocytes of BLV-infected cows the mean values of telomerase expression determined in real-time PCR were 3534.12 copies, in the healthy group there were 1010.10 copies and these differences were also statistically significant. For telomere length evaluation the Telomere PNA/FITC FISH and Telomere PNA/FITC FISH for flow cytometry were used. The mean fluorescence intensity of telomere sequences calculated on the surface of interphase nuclei of leukaemic blood lymphocytes was lower than that in the control animals and the difference was statistically significant. The mean length of telomeres in BLV- infected and healthy cows was 31.63 ± 12.62 and 38.4 ± 4.03, (p=0.112), respectively.

Go to article

Authors and Affiliations

M. Szczotka
J. Kocki
E. Iwan
A. Pluta
Download PDF Download RIS Download Bibtex

Abstract

On the basis of 35 one-hour series of the measurement of the wind velocity, read out every two minutes, the wind structure at the Arctowski Station, situated on Admiralty Bay, King George Island, was analysed. Very strong turbulence was found with air flow directions from over the area of the Island (S, SW. W and NW) and laminarity with directions from SE, E, NE and partly N, i.e. when the air flows from Admiralty Bay or from over the open waters of Bransfield Strait. The qustiness coefficient, the relationship between the maximum and mean velocities and the intensity of turbulence were determined for the two flow types. Two extremely different cases, in terms of flow character, were considered, by determining for them the distributions of instantaneous velocities and those of oscillations.

Go to article

Authors and Affiliations

Dominik Kowalski
Download PDF Download RIS Download Bibtex

Abstract

In this paper a system of a grid side and a generator side converters, both working with a common capacitor, is presented. The 6-phase asymmetric inset-type SMPMSM generator is used. A large pole pair number of this generator enables a gearless wind turbine operation. The fundamental and 3rd harmonic cooperation is used to increase the generator performance. This is accomplished by means of the 3rd harmonic current injection. For that reason the generator side converter must have a neutral connection.

Go to article

Authors and Affiliations

Marek Gołębiowski
Lesław Gołębiowski
Damian Mazur
Matthias Humer
Download PDF Download RIS Download Bibtex

Abstract

We współczesnych dyskusjach na temat racjonalności nauki spór dotyczy m.in. odpowiedzi na pytanie, czy istnieją uniwersalne reguły akceptacji, odrzucania lub wyboru koncepcji teoretycznych, zasługujące na miano racjonalnych. Pluralizm i relatywizm kryteriów racjonalności ma zdecydowanie więcej zwolenników. Odrzuca lub w znacznym stopniu kwestionuje klasyczne pojęcie racjonalności nauki jako poznania w pełni obiektywnego, prawdy jako jego celu oraz autonomicznego podmiotu jako jego twórcy. Czy Kant uznałby podnoszone w nieklasycznym ideale relatywność i wielość celów nauki i kryteriów racjonalności? Charakteryzując rolę podmiotu i zasad rozumu w systemie Kanta, formułuję tezę, że filozof ten broniłby potrzeby połączenia różnych, nawet początkowo niewspółmiernych teorii i aspektów doświadczenia w spójną całość, traktując to jako wymóg racjonalności nauki, i szerzej, racjonalności człowieka, jako istoty rozumnej i autonomicznej, twórcy zasad wyznaczających ludzkie poznanie i działanie.

Go to article

Authors and Affiliations

Marek Maciejczak
Download PDF Download RIS Download Bibtex

Abstract

Selected results of investigations concerning a shallow water part of the coastal zone, covering the surf zone and the swash zone, are presented. The above research has been carried out by means of field measurements, as well as data-driven and theoretical modelling. The investigations have led to development of a mathematical model of wave transformation and run-up on the shore in the Lagrangian system, as well as identification of infragravity waves (edge waves) in the multi-bar morphological beach system and their linkage with rhythmic shoreline forms (cusps). Some empirical relationships have been obtained for the description of number of bars in a bar system and dissipation of wave energy over such morphological structure. The experimental findings are based on field studies carried out at the IBW PAN Coastal Research Station (CRS) in Lubiatowo.

Go to article

Authors and Affiliations

J. Kapiński
R. Ostrowski
Z. Pruszak
G. Różyński

This page uses 'cookies'. Learn more