Mappings of Ruled Surfaces in Simply Isotropic Space <Emphasis Type="Italic">I</Emphasis><Subscript>3</Subscript><Superscript>1</Superscript> that Preserve the Generators

In this paper we study some mappings of skew ruled surfaces in simply isotropic space which preserve the generators. We study isometries, conformal mappings and mappings which preserve the area. Furthermore, we study mappings of surfaces in I ₃ ¹ which preserve the asymptotic lines.Received December 18, 2001; in revised form July 12, 2002 Published online April 4, 2003     

Improved liquid chromatographic method with pulsed electrochemical detection for the analysis of gentamicin

The official method for the determination of the composition and related substances of gentamicin prescribed by the European Pharmacopoeia (Ph. Eur.) is liquid chromatography combined with pulsed electrochemical detection (LC-PED). However, this method utilizes a polymer stationary phase which shows rather low efficiency towards the separation of the main gentamicin components. Moreover, the mobile phase contains a lot of non volatile salts: sodium sulphate and sodium octanesulphonate. Following a comparative study, the most performant LC-PED method has been evaluated and validated using a reversed phase C18 column (C18, 250 x 4.6mm ID, 110 A, 5 microm) kept at 35 degrees C with a mobile phase containing volatile ion pairing agents: trifluoroacetic acetic acid (TFA) and pentafluoropropionic acid (PFPA). In addition to the selectivity of the main gentamicin components and its related substances, the method is repeatable, linear and proves to be robust. It is also applicable to a wider number of C18 columns.     

A new method for strategic decision-making in higher education

Central European Journal of Operations Research - Using the appropriate methodology for strategic decision-making in higher education is crucial to make effective decisions. In this paper, the...     

Enhancing Mathematics for Informatics and its correlation with student pass rates

In this article, changes in Mathematics for Informatics at the Faculty of Organisation and Informatics in the University of Zagreb are described, and correlated with students pass rates. Students at the Faculty work in an interdisciplinary field, studying Informatics within a business context. The main reason for introducing the changes in the curriculum and its delivery, reflecting internal pressures, was the very low student pass rate in Mathematics. The second reason, reflecting external pressure, was to address the requirements of the Bologna declaration in higher education in Croatia. The innovations were introduced in the following areas: content, methodology of teaching and learning, examination methods and support for students. The changes resulted in a significant increase in student pass rates and levels of student satisfaction.     

Decision-making on prioritization of projects in higher education institutions using the analytic network process approach

The prioritization of projects in higher education institutions is a complex decision-making problem. In this paper we deal with two scenarios within Higher Education Institutions. The first scenario is a need to prepare an action plan for activities that will result in the implementation of a portfolio of projects at the institutional level. The second scenario is making a decision on whether to start a new project application, and if so, which project to choose in a situation where project teams have several project ideas and limited resources. The purpose of the paper is to show how to include corporate strategy in the decision-making process and use the Analytic Network Process as a multiple criteria decision-making methodology which can be used in solving project selection problems.     

Prioritization of e-learning forms: a multicriteria methodology

Strategic planning of e-learning implementation includes decision making about the most suitable form of implementing e-learning on different levels in an institution. Decision making about e-learning implementation has been covered as consisting of four phases: (1) intelligence, (2) design, (3) choice and (4) implementation. During the Intelligence phase we have precisely identified our central decision problem and have conducted situation analysis. In the Design phase we have developed alternatives and established criteria and subcriteria. The questionnaire about the importance of the advantages and goals of e-learning implementation and about criteria and subcriteria significant for decision making was created. Essential for the survey was use of Croatian e-learning experts that are familiar with higher education (HE) environment. Further, we connected these findings with the results of the factor analysis which was performed on the survey. The results of the factor analysis have served as input in the multicriteria decision model (AHP) that we have developed in the Choice phase. In the implementation phase we have solved the problem of prioritisation of e-learning options with the help of multi-criteria modelling in the process of group decision making. In this article, firstly we will present and analyze the results of the survey. Secondly, the outputs of factor analysis will be stated and compared with the model used in the questionnaire. Finally, the structure of AHP model will be given and the results of the quantitative evaluation of the model will be presented.     

Minding isometries of ruled surfaces in pseudo-Galilean space

In this paper we study the Minding isometries of skew ruled surfaces in pseudo-Galilean space. The Minding isometries are isometries of ruled surfaces which are also generator-preserving. The obtained results can be easily transfered to the ruled surfaces in Galilean space.     

Determination of bromide, bromate and other anions with ion chromatography and an inductively coupled plasma mass spectrometer as element-specific detector

An implementation of the Dionex IonPac AS12A analytical column with an element-specific ICP-MS detection is described for the simultaneous determination of halogen and oxyhalogen anions, sulfate, phosphate, selenite, selenate and arsenate. The chromatographic separation was achieved in less than 4 min with an aqueous 11 mM (NH4)2CO3 (pH 11.2, adjusted with aqueous ammonia) as eluent. Special emphasis was given to optimize the ICP-MS detection conditions for the reliable detection (RSD<5%) of bromate and bromide at a bromine concentration level of 1.0 microg l(-1) with 50 microl sample injection volume. In order to achieve the highest detector response for bromine species an ultrasonic nebulizer equipped with a membrane desolvator had to be employed. The detection limits (S/N=3, sample injection volume 50 microl) obtained with the IC-ICP-MS after the optimization were 0.67 microg l(-1) for BrO3-, 0.47 microg l(-1) for Br-, 69 microg l(-1) for ClO2-, 4 microg l(-1) for Cl-, 47 microg l(-1) for ClO3-, 13 microg l(-1) for SO4(2-), 36 microg l(-1) for PO4(3-), 0.4 microg l(-1) for SeO3(2-), 0.3 microg l(-1) for SeO4(2-), and 0.4 microg l(-1) for AsO4(3-).     

Special curves on ruled surfaces in Galilean and pseudo-Galilean spaces

We develop the theory of ruled surfaces in the pseudo-Galilean space G ₃ ¹. Furthermore, we prove the Bonnet theorem and investigate the osculating quadrics for ruled surfaces in G ₃ ¹as well as in the Galilean space G ₃. This revised version was published online in June 2006 with corrections to the Cover Date.