Placing emphasis on high level of responsibility, professionalism and tendency for improvement is expected from medical students. A continuous flow of information puts medical students in front of a choice between the already known and the new. It is therefore necessary to think flexibly and to be ready to verify information and admit mistakes – it is necessary to be able to think critically. While studying chemistry in Riga Stadiņš University, students have an opportunity to use critical thinking methods for certain purposes – investigation of laws of nature. Development of critical thinking therefore is an integral component rather than the goal of medical education. A complex education method with linked didactic methods was developed – the goals are development of critical thinking during practical work, development of study process organization skills, and critical analysis of information, situation modelling, self-assessment and self-dependence. In order for used didactic methods to work, levels of student qualification were taken in consideration and students were offered an opportunity to evaluate their work themselves. By adapting different forms of studying to each topic of theoretic course and practical work, it was possible to find the most effective as proven by student questionnaires. As research shows, the most effective didactic methods are: 1) special assignments where students have to verify given facts; 2) situations where students are directed towards intensified analysis of conditions of assignment; 3) mastering of science-based research principles which include promotion of theories, practical testing, result analysis, and conclusion drawing.

It is important to define which of the plant growth factors determines the yield level. During recent years in Latvia, in most cases it was moisture. Grain yield level mostly depends on meteorological conditions during the tillering stage. Plants do not utilize all water from precipitation. Rain water efficacy depends on soil granulometric composition and content of humus. Humus content could be considered as regulated factor. Important is also distribution of precipitation during the vegetation period as well as run-off of rain water which depends on micro-relief, soil tillage type, and direction in accordance with the slope gradient. It is very important for cereal growing in what conditions tillering is done, because during that time productive stems as well as ear sprouts are formed. The aim of this research was to determine the effect of soil moisture on the growth and development of winter wheat Triticum aestivum L. Field trials were carried out during 2005-2007 in Kurpnieki field at the Research and Study farm „Vecauce” of the Latvia University of Agriculture. A total of 47 points (distributed as a grid of 50×50 m) were selected for sampling in the winter wheat field. In both experimental years, the increasing soil moisture in spring had a significant positive effect on the flag leaf area, which, in its turn, increased also the level of grain yield. Partial correlation analysis showed that exclusion of organic matter content and altitude above the sea level as factors, changes soil moisture at different layers of the soil insignificantly.

Winter rape (Brassica napus L.) significance among field crops is unchangeable for last decade in Latvia. Rape plant development in autumn, plant wintering and plant yielding is partly influenced by plant density. The aim of our research, started in autumn 2007 in the Research and Study farm ''Vecauce'', was to investigate the influence of agro-ecological factors (sowing date, sowing rate and fungicide (as growth regulator in autumn) application) on two type (line and F1) winter rape varieties' plant density in autumn, in spring and at harvesting. Plant density in autumn, in spring and during harvesting was determined also by meteorological parameters as air temperature and precipitation. Oilseed rape field germination was observed from 84% sown on 1st of August in 2007 till 67% sown on 1st of August in 2008. A significant impact (p is less than 0.05) of the sowing rate was noted for plant winter hardiness (in points) for variety 'Californium' in both years: 2008 and 2009. Fungicide application effect on plant survival during winter was observed for treatments with greater plants density. A very little average plant number decrease per square m during summer growth period was noted for all treatments in both years - within 1 to 4% in some cases. The tendency was observed that final plant density at harvest if greater sowing rates had been used, was never high on average for 'Californium' from 75 plants per 1 square m (120 germinable seeds per square m) to 60 plants per 1 square m (100 germinable seeds per square m) in 2009. Correlations between plant density at harvest time and seed yield were found.

Precocity of fruit plants enables early obtaining of yield and income. But precocity can be influenced by drought. In some cases precocity is related to insufficient growth and insufficient yield in the succeeding years. The precocity of sour cherries was investigated in the trial established at the Latvia State Institute of Fruit Growing. Soil moisture treatments - woodchip mulch and drip irrigation as well as cultivars ‘Bulatnikovskaya’, ‘Desertnaya Morozovoi’, ‘Latvijas Zemais’, ‘Orlica’, ‘Shokoladnica’, ‘Tamaris’, and ‘Zentenes’ were used as trial factors. The flowering and yielding was observed in 2008 and 2009. Flowering, fruit set, fruit mass, and yield were characterized in order to evaluate precocity of cherries in different soil moisture treatment variants. The use of drip irrigation did not influence the yield of sour cherries, but the use of woodchip mulch decreased the yield in the third growing year. The cultivar ‘Tamaris’ was the most precocious, and the cultivar ‘Bulatnikovskaya’ was the most productive.

Cultivars of northern highbush blueberries (Vaccinium corymbosum L.) are the most suitable for areas with long, cold winter, because they require the greatest number of winter chilling hours. The blueberries are excellent sources of phytochemicals that are believed to have a significant biological activity. The experiment was done at the Institute of Agrobiotechnology, Latvia University of Agriculture, Jelgava, in the year 2009. The aim of the experiment was to evaluate phenological development of 9 highbush blueberry cultivars, their yield, fruit weight and biochemical composition: total anthocyanins, total phenols, ascorbic acid, titratable acids, and soluble solids. The obtained data showed correlation between duration of flowering and fruit ripening; between harvest and end of vegetation period of the highbush blueberry. The phenological development was dependent not only on cultivars, but also on the effective air temperature (above + 5 deg C). The research results allow assessing the phenology development of blueberry cultivars and predicting the fruit ripening time in conditions of Latvia. The most productive cultivars were 'Patriot' and 'Northland' The biggest single berry weight presented the cultivars 'Chippewa' and 'Bluejay'. The cultivar 'Jersey' had the highest content of titrable acid, anthocyanins, and ascorbic acid. The highest phenol content was detected in highbush blueberry cultivars 'Spartan' and 'Bluecrop'.

Pollution of atmosphere and decrease of fossil fuels stimulates people to search for an alternative energy sources for production of energy, both electrical and heat. In Latvia it is possible to use almost all alternative energy sources for production of energy, including solar energy that becomes more relevant year by year. Solar radiation in direct way makes no hazardous, but, as the intensity of solar radiation in geographical location of Latvia is comparatively low, the utilization of it demands relatively expensive equipment. Production of energy from other sources of energy also demands certain investments as well as the purchase of fuel, maintenance of equipment and presence of different manipulators. In practice several types of solar collector constructions with efficiency from 30 up to 75% exist and expenses vary in the wide range. The average number of sunshine hours in Latvia is about 1800 hours yearly. Nevertheless solar collectors for water heating in Latvia are used. Mostly flat-plate collectors are used whose efficiency often is not sufficient and water has to be additionally warmed-up. The aim of our investigation is to study operation of evacuated tube collector in conditions characteristic to Latvia. It is stated that it is feasible to use evacuated tube collector for water heating in Latvia, especially from March till October. During winter period solar collector can be used as additional energy source for water heating.

This paper presents results of pressure oscillation investigation in hydraulic hitch-system of a tractor Claas Ares ATX 557 during the motion during artificial roughness road test. During experiments oscillation at different driving speed, tyre pressure and hitch-system oscillation damping (turned on/off) were investigated. Tractor hydraulic hitch-system was equipped with a pressure sensor Wika Transmitter ECO-1 and data processing software PicoLog. Results of experiments present maximum pressure peak of 210 bar in the tractor hydraulic system when hydraulic hitch-system oscillation damping system at driving speed 8 km·hE-1 is not used and system pressure peak reduces to value of 180 bar if the hydraulic hitch-system oscillation damping is used.

Dairy ecosystems have been developing in thousands of years giving us wonderful collection of different types of cheese varieties. On the other hand, modern technology provokes the loss of variability (Adamberg et al., 2007). The only way to keep biological processes under control is to study physiology of microorganisms, and relationships between them systematically, especially non-starter lactic acid bacteria (NSLAB). The number of non-starter lactic acid bacteria increases during cheese ripening and may constitute a dominant population in the mature cheese. The NSLAB diversity, their metabolism and interactions with starter bacteria have an effect on the ripening process of the cheese. The aim of the present study was to investigate the diversity of Lactobacillus spp. during ripening of Krievijas cheese. The diversity of different profiles varied among the cheese samples matured at different temperatures, and the results indicated a correlation between NSLAB species and aroma development (Miķelsone et al., 2009). A higher metabolism of Lactobacillus curvatus at 12 deg C leads to faster depletion of nutrients and approaching the last two phases of microorganism growth curve. However, in each of the cheeses, the microflora had a tendency to be dominated by one Lactobacillus profile at the end of maturation.

This study was undertaken to assess the potential for sweet potato silage making business by estimating sweet potato vines and root wastage and assessing the economic feasibility of investing in sweet potato silage. Information was collected through key informant interviews, secondary data review, sweet potato root peeling and weighing, focus group discussions with pig and sweet potato producers covering a sample of 180 farmers. Semi-structured interviews with 240 respondents (120 sweet potato farmers, 60 pig farmers and 60 sweet potato traders) were also conducted. The results showed that sweet potato production is seasonal with substantial wastage of sweet potato components existing across the various nodes of the sweet potato value chain. The study concludes that there is an opportunity for investment in sweet potato silage business that has the potential to reduce wastage of sweet potato and bridge the feed scarcity gap faced by pig farmers.