Time filter

Source Type

Bialystok, Poland

Morzycki J.W.,University of Bialystok
Steroids | Year: 2011

Over the past decade, ruthenium-mediated metathesis transformations, including cross-metathesis, ring-closing metathesis, enyne metathesis, ring-opening metathesis polymerization, and also tandem processes, belong to the most intensively studied reactions. Many applications of olefin metathesis in the synthesis of natural products have been recently described. Also in the field of steroid chemistry new methods of total synthesis and hemisynthesis based on metathesis reactions have been elaborated. Various biologically active compounds, e.g. vitamin D and hormone analogues, steroid dimers and macrocycles, etc. have been prepared using a variety of olefin-metathesis protocols. © 2011 Elsevier Inc. All rights reserved. Source

A concentration-dependent increase in activity of antioxidant enzymes (catalase, ascorbate peroxidase, glutathione reductase, ssuperoxide dismutase) and the level of total ascorbate and reduced glutathione have been observed in the green alga Chlorella vulgaris following heavy metals exposure. It was arranged in the following order: copper > lead > cadmium. It was also found that brassinolide activated enzymatic and non-enzymatic system in C. vulgaris cultures treated with heavy metals. Brassinolide plays an important role in plant responding to heavy metals' stress. It has an anti-stress effect on C. vulgaris contaminated by heavy metals. © 2009 Elsevier B.V. All rights reserved. Source

Kaczorek T.,University of Bialystok
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011

A new class of positive linear systems consisting of n subsystems with different fractional orders is introduced. Solution to the set of matrix linear differential equations with different fractional orders is derived. Necessary and sufficient conditions for the positivity of the fractional systems are established. It is shown that the linear electrical circuits composed of resistors, supercondensators, coils, and voltage (current) sources are positive systems with different fractional orders. © 2006 IEEE. Source

Bartosiewicz Z.,University of Bialystok
Mathematics of Control, Signals, and Systems | Year: 2013

Positive linear systems on arbitrary time scales are studied. The theory developed in the paper unifies and extends concepts and results known for continuous-time and discrete-time systems. A necessary and sufficient condition for a linear system on a time scale to be positive is presented. Properties of positive reachable sets are investigated and characterizations of various controllability properties are presented. A modified Gram matrix of the system is used to state necessary and sufficient condition of positive reachability of a positive system on an arbitrary time scale. © 2013 The Author(s). Source

Honko P.,University of Bialystok
Information Sciences | Year: 2013

We propose a novel framework for association discovery from relational data. The framework is a specialized version of the general framework intended for mining relational data and is defined in granular computing theory. In the framework proposed in this paper we define a method for deriving information granules from relational data. Such granules are the basis for association discovery. Our framework, unlike others, unifies not only the way the data and patterns to be derived are expressed and specified, but also partially the process of discovering patterns from the data. Namely, the patterns can be directly obtained from the information granules or constructed based on them. Moreover, the information granule-based relational data representation, defined in the framework, can be treated as the search space for association discovery. Thanks to this the size of the search space may significantly be limited. Furthermore, we apply in our approach the granular computing idea of switching between different levels of granularity of the universe. Thanks to this relational data representation can easily be replaced by another one and thereby adjusted to a given data mining task, e.g., association discovery. The results of preliminary experiments show that granular representation of relational data can be powerful enough to generate essential patterns. © 2013 Elsevier B.V. All rights reserved. Source

Discover hidden collaborations