Approach of white box mathematical modelling was used to develop dynamic mathematical model of glycerol cycle in baker's yeast Saccharomyces cerevisiae and by deterministic simulations explore an interaction between glycerol cycle and glycolysis. The key process in research was reaction of artificially expressed glycerol-2-dehydrogenase (Gld2) which catalyses glycerol transition into dihydroxyacetone and reduced nicotinamide adenine dinucleotide phosphate (NADPH). We put forward hypothesis that expression of Gld2 in S. cerevisiae could increase concentration of reduced cytosolic NADPH. Michaelis-Menten equation was used to describe a rate law of reactions of the model of glycerol cycle. Kinetic parameters Km (Michaelis - Menten constant) and Vmax (maximal velocity of reaction) were taken from BRENDA database and publications. To perform deterministic simulations of the model of glycerol cycle and glycolysis, an accomplished model of glycerol cycle was introduced into the mathematical model of glycolysis of Nielsen et al. (1998). Results suggested that Gld2 reaction could run even without glycolysis as long as glycerol and oxidized nicotinamide adenine dinucleotide phosphate (NADP+) was present in the system. Intracellular concentration of glycerol had a direct impact on formation and acumulation of dihydroxyacetone. Reduced nicotinamide adenine dinucleotide (NADH) concentration decreased significantly and rapidly when glycerol cycle was switched on suggesting that it could be a limiting factor of the system.

A lot of different EU directives and regulations set the targets to decrease greenhouse gas emissions, to increase the share of renewable energy, and to improve energy efficiency. Biofuel usage is directly linked to all of these problems. Since the first generation food-based biofuels should not receive public support after 2020, investigations of next generation biofuels are topical. Hydrotreated vegetable oil (HVO) is one of the most promising next generation biofuels in the near future. This article deals with the results of mathematical modelling to determine the main diesel engine operating parameters (power, torque and fuel consumption) running them on HVO and its blends with fossil diesel fuel. The modelling results of the car Opel Insignia 2.0 CDTi show that every 5% of HVO in fuel blend reduces maximum power and torque of around 0.38% while raising specific fuel consumption by volume of around 0.10%. Analyzing the most realistic scenario in the near future – 7% HVO and 93% fossil diesel blend, the predicted fuel consumption increase (0.14%) and power and torque decrease (0.54%) is inconsiderable for vehicle exploitation, and HVO seems to be a promising biofuel to replace biodiesel in fuel blends and to promote reaching the EU targets.

The paper discusses heat transfer and the step response of a low-power induction motor to no-load mode under fan cooled and naturally cooled conditions. In Latvia University of Agriculture (LUA) in the electric drive laboratory the experimental tests were performed on a 1.1 kW totally enclosed fan cooled three phase induction motor with a fan mounted on a shaft for fan cooled conditions and with a fan taken off for naturally cooled conditions. The transient temperatures are measured in nine points of the stator end windings and in two points of the stator frame using thermocouples. Temperature is measured by using K type thermocouples and Pico-Log TC – 08 data logger. The current and voltage are measured by using Simple Logger II L562 two channel data logger. Measurement data are processed and archived using data loggers Pico-Log Recorder, Simple Logger II and Data View software. The experimental test results show that ventilation plays an essential role in the heating process of small power induction motors. Mathematical and virtual models of induction motor windings heating are represented to simulate the heating process of induction motor under no-load mode and different cooling conditions.

The growing popularity of wooden panels renders this market segment increasingly competitive. The article describes a new type of fibre boards e.g. the furniture production, developed in cooperation with ATB (Leibniz-Institute for Agricultural Engineering Potsdam-Bornim) by using a new method of raw material preparation and specific production technologies of ATB. The main raw material is preserved hemp (Cannabis sativa) stalks. The samples are made of raw materials with different wet-preservation time and varying types of binder. For the first time there is used main raw material with short time wet-preservation. Samples that are 8 mm thick correspond to a medium-density fibreboard and that are 16mm thick correspond to a low-density fibreboard, fitting in its mechanical properties to standard BS EN622. On ATB’s experimental processing line 1,200x800x8 mm and 1,200x800x16 mm size board samples are produced and the tests are performed to determine such parameters as bending strength, thickness swelling and thermal conductivity according to EU standard methods.

The paper presents an approach for the analysis of rural areas’ socio-economic development. Rural regions include spheres of human activity: institutional, environmental, social, labour, industrial, economic, technological development spheres. Under the development of the rural regions, changes in the variables of different spheres of human activity in the region, increasing the potential for human development, is understood. Human Development Index measures the potential for human development measurement. The model of socio-economic development of the rural regions presented in the article is characterized by both endogenous and exogenous variables of the model. Model of socioeconomic development of the rural regions is presented in the form of six econometric equations, each of which is an ADL-model. Each ADL-model contains endogenous and exogenous variables. The article presents the structural form of a system of economical equations in each one equation there is more than one endogenous variable. It shows the transition from the structural form to the form of the system of economical equations, where each equation has only one endogenous variable. The system of equations was developed for the rural regions of Russia. Baseline data were obtained from the database of the State Statistics Committee of Russia. The article provides a solution to the system of equations. The solutions to the model can be used for developing strategic development of each separate rural region or a combination of all the rural regions.

In foreign studies Latvia is positioned as a ‘depressive’ region in the year 2030, which will have an insufficient population of young people. Thus, Latvia as a country with a business-friendly environment will not be able to be competitive relative to other European countries and the flow of investment will be at risk, as well as passed on other, more competitive and better developed regions in demographic terms (Grinevica et al ., 2016). It is one of the main reasons to deal with the youth unemployment problem and to realize the actuality and consequences. Also, one of the EU’s priorities of development is to reduce youth unemployment. National labour force surveys (Hoffman, 2011) show that since 2008 the youth unemployment rate has risen in all the EU countries (Hjūza & Borbējs-Pece, 2012). The current economic instability in the context of youth’s prospects and opportunities in the labour market is uncertain (Balan, 2014). Youth unemployment has also a negative effect on economic growth and productivity. The aim of the paper is to identify the importance of unemployed youths and draw the society’s attention to the consequences. The paper presents a brief analysis of importance of unemployment costs as well as the calculation of an economic loss from youth unemployment in Latvia. The result was calculated using Okun’s Law concept.

The plants emit different types of volatile organic compounds (Bio VOC’s) and can improve air quality: they effectively remove organic pollutions and reduce the number of microorganisms in the air by releasing phytoncides. The lack of negative ions in the air can cause deterioration of the health of humans breathing it. At the same time, an air saturated with negative ions can improve the state of health and provide a comfortable environment. In this article, the influence of the plants (Cupressus macrocarpa) on the number of ions is proved, based on a series of experiments performed with applying high-voltage pulses (air ionizer). This work is devoted to the elaboration of the mathematical relationship between the air ions concentration and the factors influencing it. For this purpose an experimental stand was made, consisting of two equal compartments: one contained the plants while another one was used as a control without plants. It was concluded that the plants, in general, are able to stabilize the ion concentration and to reduce its fluctuations. The plants help to increase the concentration of negative ions and to decrease the concentration of positive ones.

Agriculture not only supplies food and fibre to the society, but also provides other services, which are not revealed in the market prices. The role of agricultural activities is essential in forming and improving the landscape, in particular, for Lithuanian case study. Therefore, the paper focuses on development of the framework for estimation of consumers’ willingness to pay for agricultural landscape improvements. The objectives of this paper are to present construction of the estimation framework for eliciting willingness to pay (WTP) for non- market agricultural landscape goods through choice experiments (CE) in Lithuania; then, to show the results of framework pre-test, and identify applicability of the framework designed. CE is a survey-based method implying creation of repetitive choice situations about alternatives of agri-environmental schemes for revealing how inhabitants of Lithuania value public goods from agricultural landscape (scenic views, variety of flora and fauna species, recreational infrastructure and services, the objects of cultural heritage), enabling to estimate Lithuanian residents’ WTP and the demand for improvements of agricultural landscape. The results of the pilot survey have shown that the questionnaire was comprehensible and interesting to the respondents, revealing that the valuation of agricultural landscape is in demand by the society. The results of modelling, applying conditional logit, have shown a good model fit, allowing the usage of the estimation framework for the main survey and an estimation of consumers’ willingness to pay for public goods/improvements from agricultural landscape.

Non-bank crediting has become popular in Latvia as well as in other European countries due to various economic and social factors. Since the banks in recent years have introduced much stricter lending conditions, non-bank crediting sector has experienced a significant increase not only in Latvia but also in other European and world countries. Non-bank crediting market actively began to develop through a wide promotion of consumer credits in the major mass media; thus, creating human interest in the availability of fast and easy processable credits. Non-bank credit companies without customer deposits have transformed the present credit market, since a number of new players entered the market testing new business and crediting models and providing solutions to credit-challenged customers. The research aim is to study the non-bank consumer crediting trends in Latvia and it employs a monographic descriptive method as well as the methods of analysis and synthesis and graphics. The research results demonstrate that the popularity of non-bank credits is still growing among consumers, since the total amounts of non-bank credits disbursed for the first time have increased by EUR 116.61 million or 33.18% for the period 2012-2015 with distance credits being the most demanded credit type accounting for approximately 40% of all non-bank credits. Non-bank credit market is saturated and there is a fierce competition between non-bank crediting companies in terms of interest rates, crediting conditions and other factors.

Experience saved in the construction industry shows that the timber portal frames with semi-rigid connections at knee joint exhibit permanently increase displacements at the knee and apex point. Normally, timber portal frame with semi-rigid knee joint connection is made with mechanical fasteners located in double circles and cannot be designed without relevant rotation at connection during structures’ exploitation time. The only way to increase connection rigidity is to rise distance from fasteners location at connection, but at the same time, the tension and shear stress become significant at the external section of members. The previous experience is obtained by a model testing showing that deformations at semi-rigid connections are non-linear. These were tests under short-term load and did not disclose creep effects, which can be significant. This study is aimed at the examination of increasing deformations with time under constant static load (creep effects) in semi-rigid dowelled connection. Experimental test models were made and set under long-term load in controlled environmental conditions (heated laboratory room). Results show a significant creep influence to decrease connection stiffness. Corresponding numerical test of orthotropic 3d model by Dlubal RFEM software tools was performed analysing the value of expected deformations. Results of the numerical test showed that friction between timber elements and extra nuts on bolts can increase connection stiffness. Research results in this stage show that the creep can affect connection stiffness more than expected. Also, experimental test results showed lower deformation values comparing with the ones obtained by the numerical test.