Klaipėdos universitetas

Disc brooches of Dollkeim-Kovrovo culture attributed to the Early Roman Period are characterised by the complicated archaeological context. Distant analogies in Roman disc brooches, the different morphology and technique leave open the question of their origin. This article proposes an analysis based on the verification of archival data, publications and surviving archaeological items from the collection of the former Prussia-Museum.

This paper proposes methodology for companies’ assessment. There is suggesting assessing the company’s prospect, not only according to share price, forecasts of the analysts, but also on the basis of position of each company in two-dimensional space in respect of the other companies. Seeking to describe the share prices of a company during the year, the parameters of skew t distribution are calculated. Then they are used in the inputs of random forest algorithm. Proximity matrices are stored during classification, and they are displayed in two-dimensional space. Thus, two clusters are obtained: one of the companies with upgrade trend, another one – with downgrade trend. This method may be useful those investors who are important to choose the most promising companies of all industry without wasting a lot of time.

The Lithuanian coast of the south eastern part of the Baltic Sea represents a generic type of more or less straight, high-energy (in the Baltic Sea conditions), actively developing coasts that contain a relatively large amount of finer, mobile sediments, are open to predominating wind directions and are exposed to wave activity for a wide range of wave approach directions. The combination of the angular distribution of winds and the geometry of the coast are such that the wave-induced long-shore sediment transport is, in average, to the north over the entire Curonian spit and the mainland coast of Lithuania. Analysis of the field data performed by the G. Žilinskas (2008) from 1976-2007 revealed that the length of accumulative sections has been considerably reduced. Accordingly, the length of the gradually eroding sectors has increased in the end of the 20th century. In this study were analised potential variations in the long-shore sediment transport rate due changes of the wind wave directions.

Physical and chemical parameters were measured in a mostly freshwater estuarine lagoon in the SE Baltic. Present paper demonstrates an attempt to trace the sources and analyse the seasonal and spatial patterns of distribution of POC, DIC and DOC in the Curonian lagoon mostly by the isotopic content in different forms of carbon. Samples were collected in 2012-2014 in 9 stations in the Curonian lagoon including riverine and marine input/output stations. Riverine inputs and summarizing outflow to the Baltic sea locations (Nemunas river delta and Klaipeda channel stations were sampled monthly, while POC, DIC and DOC samples in other stations were collected on a seasonal basis. The observed results allow easily differentiate between estuarine and riverine POM samples, while the differences in DOC δ13C content between sampling stations were found to be not statistically reliable. The high biological productivity of the Nemunas river along with the minor contribution of the Baltic Sea inflows to the overall hydrodynamics of the lagoon explain similarity of content between riverine and estuarine material in the spring and autumn. However, the δ13C content of DIC and DOC could serve as indicator of external inputs only in connection with seasonal water residence variations.

This paper proposes an algorithm for construction of C2 surface. The input is a 3D quadrangular surface which doesn't have adjacent extraordinary points. The difference between this algorithm and the regular C2 forming algorithms is a possibility to choose the natural number of points of the output grid. For example using the Catmull-Clark algorithm the same possibility corresponds exponential natural numbers where the basis is 2. The changing infinite Bezier surfaces generation process to finite calculation of necessary points leads the ability to get more results. The C2 surface generation algorithm was realized and the quality results of output surfaces were performed using reflection lines.

Lack of ICT specialists is a big problem in Lithuania for many years. Even ICT specialists are prepared both by universities and colleges, need of those specialists is increasing every year. Students’ enrolment to the ICT related study programmes is increasing a little every year, but only around 51% of them complete their studies. There are very different reasons of students drop-out: health problems, characteristics of personality (lack of responsibility, self-doubts, etc.), socio-economic factors, organisation of study process (Barkauskaitė & Gudžinskienė 2006). In this article a different approach is used to academic arrears – using statistical calculations, academic arrears of students of Vilnius University, Faculty of Mathematics and Informatics from 1991 till 2012 are analysed. At the end of the article, justification of a theoretical model is presented, using which students’ drop-out peculiarities in different study programmes can be observed.

The essential part of amperometric biosensor is an enzyme. It should be selective, i.e., react only with certain substrate. The selectivity of enzyme reduces the set of possible to use enzymes. This paper demonstrates that non selective enzymes (reacting with two substrates) can be used to determine concentrations of two substrates. For this purpose the steady-state current of two double biosensors was measured. The currents were used as input for an artificial neural network to determine concentrations of the substrates. The proposed approach was approved as the relative error of determined concentrations was relatively small. Paper analyses the influence of biosensor parameters to error values. The recommendations to error values minimisation were obtained.

In this study, an NPZD model and a trophic network model that contains organism groups on the higher trophic levels were developed and linked using the “bottom-up control” approach. Such a linkage of models provides the possibility to use the advantages of both models; reproducing of the erratic behaviour of nutrients and plankton as realistic as possible, while still taking the more complex organisms in the trophic network, which respond to external forcing in a larger time scale. The models developed in this study were applied to the Curonian Lagoon that is an important estuarine ecosystem for Lithuania. The tests and simulations have proven that the results of the NPZD model were accurate enough for representing the nutrient and phytoplankton dynamics in the Curonian Lagoon as well as spatial differences which are of ecological interest. Linkage with trophic network model demonstrated NPZD model results to be consistent with the Curonian Lagoons ecosystem. The modelling results showed that primary production is relatively high in the Curonian Lagoon and is unlikely to be controlled by the organisms that are on the higher trophic levels of the food web. Analysis of the NPZD model scenarios with different nutrients inputs revealed that phosphorus is the main limiting nutrient for primary production in the Curonian Lagoon. However, different combinations of nitrogen and phosphorus inputs control the relative abundance of different phytoplankton groups. Investigation of reaction of ecosystem to water temperature increase showed that the temperature increase finally leads to decrease of available phytoplankton to upper levels of the food web.

This work put forwards an optimal BCI (Brain Computer Interface) speller design based on Steady State Visual Evoked Potentials (SSVEP) and Artificial Neural Network (ANN) in order to help the people with severe motor impairments. This work is carried out to enhance the accuracy and communication rate of BCI system. To optimize the BCI system, the work has been divided into two steps: First, designing of an encoding technique to choose characters from the speller interface and the second is the development and implementation of feature extraction algorithm to acquire optimal features, which is used to train the BCI system for classification using neural network. Optimization of speller interface is focused on representation of character matrix and its designing parameters. Then again, a lot of deliberations made in order to optimize selection of features and user’s time window. Optimized system works nearly the same with the new user and gives character per minute (CPM) of 13 ± 2 with an average accuracy of 94.5% by choosing first two harmonics of power spectral density as the feature vectors and using the 2 second time window for each selection. Optimized BCI performs better with experienced users with an average accuracy of 95.1%. Such a good accuracy has not been reported before in account of fair enough CPM.