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The National Research Programme On Main Diseases Threatening The Life Expectancy and Life Quality of The Latvian Population: Scientific papers

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Détails du magazine
Format
Magazine
eISSN
2255-890X
Première publication
14 Sep 2008
Période de publication
6 fois par an
Langues
Anglais

Chercher

Volume 74 (2020): Edition 4 (August 2020)

Détails du magazine
Format
Magazine
eISSN
2255-890X
Première publication
14 Sep 2008
Période de publication
6 fois par an
Langues
Anglais

Chercher

10 Articles
Accès libre

Epidemiological, Clinical and Morphological Characteristics of Immunoglobulin a Nephropathy in Latvia

Publié en ligne: 22 Sep 2020
Pages: 227 - 231

Résumé

Abstract

Immunoglobulin A nephropathy (IgAN) is the most common chronic glomerulopathy with variable clinical manifestations. IgAN diagnostics became possible in Latvia in 2013. The study aim was to describe IgAN manifestations in the Latvian population by analysing epidemiological, clinical, histological data, and reveal factors that might determine the course of the disease. The retrospective, one-centre study included biopsy-proven IgAN patients over a five-year period in the Nephrology Centre at Pauls Stradiņš Clinical University Hospital. Data from inpatient and outpatient medical records were collected. The study included 69 patients with histologically confirmed IgAN (23% of all renal biopsies): 52% men with mean age of 37. More than a half of them had hypertension, changes in urinalysis and kidney structure, and GFR < ml/min before the biopsy. Pathology data stratified by MEST-C score were: M1 (93%), E1 (5%), S1 (81%), T1 and T2 (24%), C1 (18%). 20% started renal replacement therapy (RRT). Proteinuria, obesity, hyperuricemia, high total MEST-C score, and low serum C3 were associated with a worse prognosis. As a significant part of patients start RRT in the five-year period after the biopsy, the disease course is not benign. IgAN in the study population was diagnosed with clinical and histological signs of advanced disease.

Mots clés

  • glomerulonephritis
  • immunoglobulin A
  • kidney biopsy
  • nephrology
  • kidney disease
Accès libre

Relation Between Human Milk Sodium and Maternal Sodium Intake

Publié en ligne: 22 Sep 2020
Pages: 232 - 236

Résumé

Abstract

Sodium is an essential mineral, necessary for optimal development of an infant. However, its content in human milk is highly variable. The main factors influencing sodium content in human milk are the concentration of other osmoles (dominantly lactose) and time postpartum. It is still debatable if maternal sodium intake affects sodium content in human milk. Overall, Latvian inhabitants consume more sodium than recommended. Therefore, we aimed to analyse the relation between maternal sodium intake and human milk sodium content. In total, 64 human milk samples and food data from 64 participants were obtained. Sodium content was determined using inductively coupled plasma mass spectrometry. Food diary data was analysed using Finnish database Fineli. The results showed that median sodium content in human milk was 12.67 mg per 100 ml−1. Nevertheless, large inter-individual differences were observed (5.00–42.54 mg·100 ml−1). Sodium in-take among the participants was higher than the recommended 2000 mg per day (median intake — 2335.83 mg per day). Although a positive association was found between median maternal sodium intake and sodium content in human milk (ρ= 0.350, p = 0.010), a hierarchical multiple regression revealed that only infant’s age was a significant factor (p = 0.038), explaining 13% of the variability of sodium content in human milk. Sodium content in human milk is not influenced directly by maternal sodium intake, and other factors (such as lactose and potassium concentration in human milk not considered in the study) could potentially influence sodium content in human milk.

Mots clés

  • lactation
  • breastfeeding
  • nutrition
  • minerals
Accès libre

Characteristics and Outcomes of Ankle Injuries in Winter and Summer Seasons

Publié en ligne: 22 Sep 2020
Pages: 237 - 243

Résumé

Abstract

The diagnostics and treatment of ankle trauma remain challenging as they enable the patients’ return to work and ability to perform daily activities. The aim of the study was to evaluate characteristics and outcomes of ankle injuries, focusing on the trauma mechanisms in winter and summer seasons. A retrospective study was conducted of 182 patients with ankle injuries, admitted to the Hospital of Traumatology and Orthopaedics in 2014, 2015, and 2016 from the months December to February, and from June to August. Patients with supination-external rotation (SER) type ankle injuries were included in the functional outcome evaluation. Our results suggested that most of the injuries were SER type, stage IV in both seasons, and that more than 2/3 of the SER type ankle injuries that needed surgery were in the winter season. In patients with tibiofibular syndesmosis (TFS) rupture the functional results were worse than in those without TFS rupture, but in winter and summer seasons they seemed to be without statistical difference.

Mots clés

  • seasonal ankle injuries
  • supination-external rotation
  • tibiofibular syndesmosis injuries
Accès libre

Effect of Population Size on Genome-Wide Association Study of Agronomic Traits in Soybean

Publié en ligne: 22 Sep 2020
Pages: 244 - 251

Résumé

Abstract

Soybean is increasingly becoming one of the main oilseeds crops in Kazakhstan, with a major growing area in the south-eastern part of the country. The comparative assessment of small-size (108) and medium-size (276 accessions) collections of soybean originated from five regions of the world was made in field trials in Almaty region (south-east of Kazakhstan). The full collection was genotyped using the Illumina iSelect 6K SNP (single nucleotide polymorphism) array that allowed observation of 4651 polymorphic SNPs. The genome-wide association study (GWAS) was conducted using the following six important agronomic traits: flowering time, seed maturation time, plant height, number of fertile nodes, number of seeds per node, and thousand seed weight. In total, GWAS using TASSEL package identified 56 stable QTNs (quantitative trait nucleotdies) for all the studied traits, including 42 QTNs detected using the medium-size collection. It was shown that the medium-size population, in comparison with the small-size population, was preferable for the detection of significant associations. A comparative analysis of the data with previously published results suggested that 36 of the stable 56 QTNs were presumably novel associations. The revealed QTNs can be used in the molecular breeding projects for soybean yield improvement.

Mots clés

  • Glycine max
  • yield components
  • Illuminia genotyping array
  • association mapping
Accès libre

Physiological Performance of a Coastal Marsh Plant Hydrocotyle vulgaris in Natural Conditions in Relation to Mineral Nutrition and Mycorrhizal Symbiosis

Publié en ligne: 22 Sep 2020
Pages: 252 - 262

Résumé

Abstract

Fluctuating soil salinity and competition for light are the main factors affecting plant distribution and performance in coastal salt marshes. The aim of the present study was to assess plant performance by means of non-destructive instrumental methods in a highly heterogeneous natural habitat. More specifically, environmental factors affecting growth and physiological performance of a clonal plant Hydrocotyle vulgaris L. were investigated. Changes in soil salinity, soil mineral characteristics, leaf nutrient concentrations, morphological parameters, chlorophyll fluorescence, and mycorrhizal symbiosis were analysed in different experimental plots of naturally growing H. vulgaris plants. The dynamic nature of interaction between sea water flooding-affected changes in soil salinity and competition-dependent changes in light availability led to micro-environmental heterogeneity differentially affecting physiological performance and growth of H. vulgaris in natural conditions. Plant growth was mostly affected by intensity of photosynthetically active radiation in the respective plots. Increased growth rate in shaded conditions specifically pointed to shade tolerance strategy of H. vulgaris. High heterogeneity of mineral nutrients between the plots was established. However, considerable plasticity of metabolism in respect to highly variable soil concentration of mineral nutrients together with effective mineral adaptation mechanisms ensured optimal supply of material for growth. Photochemistry of photosynthesis was only marginally affected by differences in microenvironmental conditions as shown by respective changes in chlorophyll a fluorescence parameters. Mycorrhizal symbiosis was stimulated by moderately increasing soil salinity and suppressed by relatively high salinity. When the effect of soil salinity was omitted, intensity of mycorrhizal symbiosis was positively associated with intensity of photo-synthetically active radiation. In general, a relatively high stable level of photosynthetic performance across a wide range of micro-environmental conditions indicates an adequate level of physiological adaptation of H. vulgaris to conditions of a coastal salt marsh. The present data clearly reflect complex interactions between environmental factors and plastic physiological responses of H. vulgaris.

Mots clés

  • chlorophyll
  • chlorophyll a fluorescence
  • growth
  • natural conditions
  • photosynthetic performance
  • salinity
Accès libre

Optimisation of Lactose Hydrolysis by Combining Solids and ß-Galactosidase Concentrations in Whey Permeates

Publié en ligne: 22 Sep 2020
Pages: 263 - 269

Résumé

Abstract

A detailed study of lactose hydrolysis was conducted using 50, 250 and 500 units of ß-galactosidase (Kluyveromyces lactis and Bacillus licheniformis origin) in acid and sweet whey permeates at different solid concentrations 20%, 30% and 40% (w·v−1). The amount of lactose, glucose and galactose was measured by HPLC – RID. Hydrolysis was carried out at optimal enzyme temperature 42.5 °C for 4 h. Medium pH before hydrolysis was adjusted using 10% KOH. The experimental results were compared taking into account the sugar profiles and experimental conditions. The highest lactose hydrolysis occurred at solid concentration 20% (w·v−1) and at enzyme amounts of 250 and 500 units for both permeates. Using 50 units of enzymes, in many cases the amounts of glucose and galactose were more or less equal in range of 6.5–43 g·l−1 and the hydrolysis percentage was quite low in the range of 2.7–62%. Comparing both whey permeates, a higher hydrolysis percentage (99%) was obtained using acid whey and 500 enzyme units.

Mots clés

  • glucose-galactose syrup
  • enzymatic hydrolysis
  • commercial lactase
Accès libre

Performance and Stability of Agronomic and Grain Quality Traits of Latvian Spring Barley Varieties

Publié en ligne: 22 Sep 2020
Pages: 270 - 279

Résumé

Abstract

This study aimed to evaluate the performance and stability of agronomic and grain quality traits of 11 spring barley varieties from the Latvian breeding programme grown in two locations for four years. The study was carried out on 11 Latvian spring barley varieties: nine covered varieties ‘Abava’, ‘Ansis’, ‘Austris’, ‘Didzis’, ‘Gāte’, ‘Idumeja’, ‘Jumara’, ‘Kristaps’, and ‘Saule PR’ and two hull-less varieties ‘Irbe’ and ‘Kornelija’. Plants of the varieties were grown in field trials of the Institute of Agricultural Resources and Economics, at two sites (Priekuïi and Stende) during 2014–2017. Varieties ‘Didzis’, ‘Jumara’, and ‘Ansis’ yielded significantly above the grand mean in eight environments (5.70 t·ha−1; LSD = 0.476 t·ha−1). ‘Didzis’ showed relatively high dynamic yield stability and broad adaptability to all environments (bi = 0.90; b = 1; s2d = 0.07). Grain yield for varieties ‘Jumara’ and ‘Ansis’ showed specific adaptability to unfavourable environments (bi = 0.48 and 0.55, respectively; bi < 1). Some covered spring barley varieties were considered to be the best in eight environments with stable and high 1000 grain weight (‘Austris’, ‘Idumeja’), test weight (‘Gāte’, ‘Jumara’, ‘Austris’), lodging resistance (‘Austris’, ‘Jumara’, ‘Didzis’), resistance to Pyrenophora teres (‘Didzis’, ‘Saule PR’) and Blumeria graminis (‘Saule PR’, ‘Didzis’). Both hull-less barley varieties ‘Irbe’ and ‘Kornelija’ were distinguished for high crude protein and ß-glucan content.

Mots clés

  • Hordeum vulgare
  • grain yield
  • Blumeria graminis
  • ß-glucans
  • G x E interaction
Accès libre

Attitudes of the General Public and Hunters Towards Wolves in Latvia; Its Predictors and Changes Over Time

Publié en ligne: 22 Sep 2020
Pages: 280 - 286

Résumé

Abstract

A survey was carried out to determine the attitudes of the general public and of hunters towards wolves (Canis lupus) in Latvia. Today wildlife conservation depends on effective management practices; however, these are often influenced by public opinions and attitudes. Our aim was to understand the causes behind these attitudes and to compare our results with previous research done in Latvia. Questionnaires were distributed through schools and hunter organisations. The attitudes of both the general public and hunters were mostly neutral or positive. Older people and women were generally less positive. Respondents with less positive attitudes were more likely to say that wolf numbers in the country should be decreased. Significant associations between attitudes, beliefs of wolves causing damage and financial losses and what should be done with wolf numbers in Latvia were found. Three attitude predictors were established.

Mots clés

  • attitude predictors
  • Canis lupus
  • conservation
  • management
Accès libre

Stress-Deformed State of a Packing Ring with Eccentric Holes

Publié en ligne: 22 Sep 2020
Pages: 287 - 292

Résumé

Abstract

Currently, various variants of physical and geometrical non-linear calculation of anisotropic bodies have been developed. In spite of the large and increasing number of studies on the theory of shells there are still many unsufficiently developed problems important both in scientific and applied fields, for example, development of practically convenient methods for calculating of anisotropic sealing composite materials weakened by eccentric holes under the influence of local loadings. Stress-deformed state of a packing ring with eccentric holes of sealing materials was studied. In composite materials, the Hookes equation was used for this purpose. Also, using Lurie’s symbolic method, the concrete solution of the sealing problem with eccentric holes was obtained.

Mots clés

  • eccentricity
  • packing ring
  • stress
  • deformation
  • method of initial function
  • stress tensor components
  • Lurie’s method
  • dimensionless geometric parameter
Accès libre

Convective Instability of a Steady Flow in an Annulus Caused by Internal Heat Generation

Publié en ligne: 22 Sep 2020
Pages: 293 - 298

Résumé

Abstract

Linear stability of convective motion in a tall vertical annulus was analysed in the paper. The base flow was generated by a non-uniform distribution of heat sources in the radial direction. The base flow velocity and temperature were obtained analytically solving the system of Navier-Stokes equations under the Boussinesq approximation. The linear stability problem was solved for axi-symmetric and asymmetric perturbations by a collocation method based on the Chebyshev polynomials. Numerical results showed that there were three destabilising factors: (1) increase of the gap between the cylinders, (2) increase of the density of internal heat sources towards to the outer boundary of the annulus and (3) increase of the Prandtl number.

Mots clés

  • linear stability
  • Boussinesq approximation
  • collocation method
10 Articles
Accès libre

Epidemiological, Clinical and Morphological Characteristics of Immunoglobulin a Nephropathy in Latvia

Publié en ligne: 22 Sep 2020
Pages: 227 - 231

Résumé

Abstract

Immunoglobulin A nephropathy (IgAN) is the most common chronic glomerulopathy with variable clinical manifestations. IgAN diagnostics became possible in Latvia in 2013. The study aim was to describe IgAN manifestations in the Latvian population by analysing epidemiological, clinical, histological data, and reveal factors that might determine the course of the disease. The retrospective, one-centre study included biopsy-proven IgAN patients over a five-year period in the Nephrology Centre at Pauls Stradiņš Clinical University Hospital. Data from inpatient and outpatient medical records were collected. The study included 69 patients with histologically confirmed IgAN (23% of all renal biopsies): 52% men with mean age of 37. More than a half of them had hypertension, changes in urinalysis and kidney structure, and GFR < ml/min before the biopsy. Pathology data stratified by MEST-C score were: M1 (93%), E1 (5%), S1 (81%), T1 and T2 (24%), C1 (18%). 20% started renal replacement therapy (RRT). Proteinuria, obesity, hyperuricemia, high total MEST-C score, and low serum C3 were associated with a worse prognosis. As a significant part of patients start RRT in the five-year period after the biopsy, the disease course is not benign. IgAN in the study population was diagnosed with clinical and histological signs of advanced disease.

Mots clés

  • glomerulonephritis
  • immunoglobulin A
  • kidney biopsy
  • nephrology
  • kidney disease
Accès libre

Relation Between Human Milk Sodium and Maternal Sodium Intake

Publié en ligne: 22 Sep 2020
Pages: 232 - 236

Résumé

Abstract

Sodium is an essential mineral, necessary for optimal development of an infant. However, its content in human milk is highly variable. The main factors influencing sodium content in human milk are the concentration of other osmoles (dominantly lactose) and time postpartum. It is still debatable if maternal sodium intake affects sodium content in human milk. Overall, Latvian inhabitants consume more sodium than recommended. Therefore, we aimed to analyse the relation between maternal sodium intake and human milk sodium content. In total, 64 human milk samples and food data from 64 participants were obtained. Sodium content was determined using inductively coupled plasma mass spectrometry. Food diary data was analysed using Finnish database Fineli. The results showed that median sodium content in human milk was 12.67 mg per 100 ml−1. Nevertheless, large inter-individual differences were observed (5.00–42.54 mg·100 ml−1). Sodium in-take among the participants was higher than the recommended 2000 mg per day (median intake — 2335.83 mg per day). Although a positive association was found between median maternal sodium intake and sodium content in human milk (ρ= 0.350, p = 0.010), a hierarchical multiple regression revealed that only infant’s age was a significant factor (p = 0.038), explaining 13% of the variability of sodium content in human milk. Sodium content in human milk is not influenced directly by maternal sodium intake, and other factors (such as lactose and potassium concentration in human milk not considered in the study) could potentially influence sodium content in human milk.

Mots clés

  • lactation
  • breastfeeding
  • nutrition
  • minerals
Accès libre

Characteristics and Outcomes of Ankle Injuries in Winter and Summer Seasons

Publié en ligne: 22 Sep 2020
Pages: 237 - 243

Résumé

Abstract

The diagnostics and treatment of ankle trauma remain challenging as they enable the patients’ return to work and ability to perform daily activities. The aim of the study was to evaluate characteristics and outcomes of ankle injuries, focusing on the trauma mechanisms in winter and summer seasons. A retrospective study was conducted of 182 patients with ankle injuries, admitted to the Hospital of Traumatology and Orthopaedics in 2014, 2015, and 2016 from the months December to February, and from June to August. Patients with supination-external rotation (SER) type ankle injuries were included in the functional outcome evaluation. Our results suggested that most of the injuries were SER type, stage IV in both seasons, and that more than 2/3 of the SER type ankle injuries that needed surgery were in the winter season. In patients with tibiofibular syndesmosis (TFS) rupture the functional results were worse than in those without TFS rupture, but in winter and summer seasons they seemed to be without statistical difference.

Mots clés

  • seasonal ankle injuries
  • supination-external rotation
  • tibiofibular syndesmosis injuries
Accès libre

Effect of Population Size on Genome-Wide Association Study of Agronomic Traits in Soybean

Publié en ligne: 22 Sep 2020
Pages: 244 - 251

Résumé

Abstract

Soybean is increasingly becoming one of the main oilseeds crops in Kazakhstan, with a major growing area in the south-eastern part of the country. The comparative assessment of small-size (108) and medium-size (276 accessions) collections of soybean originated from five regions of the world was made in field trials in Almaty region (south-east of Kazakhstan). The full collection was genotyped using the Illumina iSelect 6K SNP (single nucleotide polymorphism) array that allowed observation of 4651 polymorphic SNPs. The genome-wide association study (GWAS) was conducted using the following six important agronomic traits: flowering time, seed maturation time, plant height, number of fertile nodes, number of seeds per node, and thousand seed weight. In total, GWAS using TASSEL package identified 56 stable QTNs (quantitative trait nucleotdies) for all the studied traits, including 42 QTNs detected using the medium-size collection. It was shown that the medium-size population, in comparison with the small-size population, was preferable for the detection of significant associations. A comparative analysis of the data with previously published results suggested that 36 of the stable 56 QTNs were presumably novel associations. The revealed QTNs can be used in the molecular breeding projects for soybean yield improvement.

Mots clés

  • Glycine max
  • yield components
  • Illuminia genotyping array
  • association mapping
Accès libre

Physiological Performance of a Coastal Marsh Plant Hydrocotyle vulgaris in Natural Conditions in Relation to Mineral Nutrition and Mycorrhizal Symbiosis

Publié en ligne: 22 Sep 2020
Pages: 252 - 262

Résumé

Abstract

Fluctuating soil salinity and competition for light are the main factors affecting plant distribution and performance in coastal salt marshes. The aim of the present study was to assess plant performance by means of non-destructive instrumental methods in a highly heterogeneous natural habitat. More specifically, environmental factors affecting growth and physiological performance of a clonal plant Hydrocotyle vulgaris L. were investigated. Changes in soil salinity, soil mineral characteristics, leaf nutrient concentrations, morphological parameters, chlorophyll fluorescence, and mycorrhizal symbiosis were analysed in different experimental plots of naturally growing H. vulgaris plants. The dynamic nature of interaction between sea water flooding-affected changes in soil salinity and competition-dependent changes in light availability led to micro-environmental heterogeneity differentially affecting physiological performance and growth of H. vulgaris in natural conditions. Plant growth was mostly affected by intensity of photosynthetically active radiation in the respective plots. Increased growth rate in shaded conditions specifically pointed to shade tolerance strategy of H. vulgaris. High heterogeneity of mineral nutrients between the plots was established. However, considerable plasticity of metabolism in respect to highly variable soil concentration of mineral nutrients together with effective mineral adaptation mechanisms ensured optimal supply of material for growth. Photochemistry of photosynthesis was only marginally affected by differences in microenvironmental conditions as shown by respective changes in chlorophyll a fluorescence parameters. Mycorrhizal symbiosis was stimulated by moderately increasing soil salinity and suppressed by relatively high salinity. When the effect of soil salinity was omitted, intensity of mycorrhizal symbiosis was positively associated with intensity of photo-synthetically active radiation. In general, a relatively high stable level of photosynthetic performance across a wide range of micro-environmental conditions indicates an adequate level of physiological adaptation of H. vulgaris to conditions of a coastal salt marsh. The present data clearly reflect complex interactions between environmental factors and plastic physiological responses of H. vulgaris.

Mots clés

  • chlorophyll
  • chlorophyll a fluorescence
  • growth
  • natural conditions
  • photosynthetic performance
  • salinity
Accès libre

Optimisation of Lactose Hydrolysis by Combining Solids and ß-Galactosidase Concentrations in Whey Permeates

Publié en ligne: 22 Sep 2020
Pages: 263 - 269

Résumé

Abstract

A detailed study of lactose hydrolysis was conducted using 50, 250 and 500 units of ß-galactosidase (Kluyveromyces lactis and Bacillus licheniformis origin) in acid and sweet whey permeates at different solid concentrations 20%, 30% and 40% (w·v−1). The amount of lactose, glucose and galactose was measured by HPLC – RID. Hydrolysis was carried out at optimal enzyme temperature 42.5 °C for 4 h. Medium pH before hydrolysis was adjusted using 10% KOH. The experimental results were compared taking into account the sugar profiles and experimental conditions. The highest lactose hydrolysis occurred at solid concentration 20% (w·v−1) and at enzyme amounts of 250 and 500 units for both permeates. Using 50 units of enzymes, in many cases the amounts of glucose and galactose were more or less equal in range of 6.5–43 g·l−1 and the hydrolysis percentage was quite low in the range of 2.7–62%. Comparing both whey permeates, a higher hydrolysis percentage (99%) was obtained using acid whey and 500 enzyme units.

Mots clés

  • glucose-galactose syrup
  • enzymatic hydrolysis
  • commercial lactase
Accès libre

Performance and Stability of Agronomic and Grain Quality Traits of Latvian Spring Barley Varieties

Publié en ligne: 22 Sep 2020
Pages: 270 - 279

Résumé

Abstract

This study aimed to evaluate the performance and stability of agronomic and grain quality traits of 11 spring barley varieties from the Latvian breeding programme grown in two locations for four years. The study was carried out on 11 Latvian spring barley varieties: nine covered varieties ‘Abava’, ‘Ansis’, ‘Austris’, ‘Didzis’, ‘Gāte’, ‘Idumeja’, ‘Jumara’, ‘Kristaps’, and ‘Saule PR’ and two hull-less varieties ‘Irbe’ and ‘Kornelija’. Plants of the varieties were grown in field trials of the Institute of Agricultural Resources and Economics, at two sites (Priekuïi and Stende) during 2014–2017. Varieties ‘Didzis’, ‘Jumara’, and ‘Ansis’ yielded significantly above the grand mean in eight environments (5.70 t·ha−1; LSD = 0.476 t·ha−1). ‘Didzis’ showed relatively high dynamic yield stability and broad adaptability to all environments (bi = 0.90; b = 1; s2d = 0.07). Grain yield for varieties ‘Jumara’ and ‘Ansis’ showed specific adaptability to unfavourable environments (bi = 0.48 and 0.55, respectively; bi < 1). Some covered spring barley varieties were considered to be the best in eight environments with stable and high 1000 grain weight (‘Austris’, ‘Idumeja’), test weight (‘Gāte’, ‘Jumara’, ‘Austris’), lodging resistance (‘Austris’, ‘Jumara’, ‘Didzis’), resistance to Pyrenophora teres (‘Didzis’, ‘Saule PR’) and Blumeria graminis (‘Saule PR’, ‘Didzis’). Both hull-less barley varieties ‘Irbe’ and ‘Kornelija’ were distinguished for high crude protein and ß-glucan content.

Mots clés

  • Hordeum vulgare
  • grain yield
  • Blumeria graminis
  • ß-glucans
  • G x E interaction
Accès libre

Attitudes of the General Public and Hunters Towards Wolves in Latvia; Its Predictors and Changes Over Time

Publié en ligne: 22 Sep 2020
Pages: 280 - 286

Résumé

Abstract

A survey was carried out to determine the attitudes of the general public and of hunters towards wolves (Canis lupus) in Latvia. Today wildlife conservation depends on effective management practices; however, these are often influenced by public opinions and attitudes. Our aim was to understand the causes behind these attitudes and to compare our results with previous research done in Latvia. Questionnaires were distributed through schools and hunter organisations. The attitudes of both the general public and hunters were mostly neutral or positive. Older people and women were generally less positive. Respondents with less positive attitudes were more likely to say that wolf numbers in the country should be decreased. Significant associations between attitudes, beliefs of wolves causing damage and financial losses and what should be done with wolf numbers in Latvia were found. Three attitude predictors were established.

Mots clés

  • attitude predictors
  • Canis lupus
  • conservation
  • management
Accès libre

Stress-Deformed State of a Packing Ring with Eccentric Holes

Publié en ligne: 22 Sep 2020
Pages: 287 - 292

Résumé

Abstract

Currently, various variants of physical and geometrical non-linear calculation of anisotropic bodies have been developed. In spite of the large and increasing number of studies on the theory of shells there are still many unsufficiently developed problems important both in scientific and applied fields, for example, development of practically convenient methods for calculating of anisotropic sealing composite materials weakened by eccentric holes under the influence of local loadings. Stress-deformed state of a packing ring with eccentric holes of sealing materials was studied. In composite materials, the Hookes equation was used for this purpose. Also, using Lurie’s symbolic method, the concrete solution of the sealing problem with eccentric holes was obtained.

Mots clés

  • eccentricity
  • packing ring
  • stress
  • deformation
  • method of initial function
  • stress tensor components
  • Lurie’s method
  • dimensionless geometric parameter
Accès libre

Convective Instability of a Steady Flow in an Annulus Caused by Internal Heat Generation

Publié en ligne: 22 Sep 2020
Pages: 293 - 298

Résumé

Abstract

Linear stability of convective motion in a tall vertical annulus was analysed in the paper. The base flow was generated by a non-uniform distribution of heat sources in the radial direction. The base flow velocity and temperature were obtained analytically solving the system of Navier-Stokes equations under the Boussinesq approximation. The linear stability problem was solved for axi-symmetric and asymmetric perturbations by a collocation method based on the Chebyshev polynomials. Numerical results showed that there were three destabilising factors: (1) increase of the gap between the cylinders, (2) increase of the density of internal heat sources towards to the outer boundary of the annulus and (3) increase of the Prandtl number.

Mots clés

  • linear stability
  • Boussinesq approximation
  • collocation method

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