Non-hierarchical Cluster Analysis Research Articles

Clustering and Tracking the Stability of Biological CVD Risk Factors in Adolescents: The Malaysian Health and Adolescents Longitudinal Research Team Study (MyHeARTs).

Background: Cardiovascular disease (CVD) risk factors tend to cluster and progress from adolescence to young adulthood. Reliable and meaningful clustering of CVD risk factors is essential to circumvent loss of information. Tracking adverse and high-risk profiles of adolescents is hoped to curb CVD progression later in life. The study aims to investigate the clustering of biological CVD risk factor among adolescents in Malaysia and the transitions between clusters over time.Method: The Malaysian Health and Adolescents Longitudinal Research Team study (MyHeARTs) examined school students aged 13 in 2012 and re-examined them in 2014 and 2016. In a two-stage stratified cluster sampling, 1,361 students were recruited, of which, 1,320 had complete data. In the follow-up, there were 881 and 637 students in 2014 and in 2016, respectively. Pearson's correlation coefficients were used to identify and remove highly correlated CVD risk factors. All risk factors were standardized into z-scores. The hierarchical and non-hierarchical (k-means) cluster analyses were used to classify students into high, medium and low risk clusters in each screening year. The tracking and stability of cluster transitions through cross-classification were enumerated with Pearson's inter-age correlations and percentages.Results: Three significant clusters of high, medium and low risk groups were derived from the clustering of eight biological CVD risk factors. The transitions between risk clusters from one screening year to the other were categorized as either stagnant, improved or adverse. The number of students who had adverse transitions increased from 15.5% (13–15 year) to 19.5% (15–17 year), 13.8 to 18.2% among the girls and 19.9 to 22.8% among the boys. For girls, the number of them who remained at high risk over the two transition periods were about the same (13.6 vs. 13.8%) whereas for boys, the percentage reduced from 14.6 to 12.3%.Conclusion: Over time, more than 12% of adolescents remained in the high risk cluster. There were sizable adverse transitions over time as more adolescents appear to be shifting toward an increased risk of having CVD. Collaborative and constant measures should be taken by parents, school, health promotion boards and policy makers to curb the multiplicative effect of clustering CVD risk factors among adolescents.

Cluster profiles of university students’ conceptions of learning according to gender, educational level, and academic disciplines

Describing university students’ profiles of conceptions of learning is an important pre-requisite in personalizing a learning process to increase its effectiveness. A person-oriented approach was assumed to identify meaningful profiles of university students’ conceptions referring to cognitive and socio-cultural, affective/motivational, and attributional/regulative components of learning. Profiles were also analyzed in relation to gender, educational level, and academic disciplines. University students (N = 243) completed a validated self-report instrument (LCQ: Learning Conceptions Questionnaire). A non-hierarchical cluster analysis (two-step method) yielded three profiles: “disengaged students”, “overwhelmed by emotions students”, and “helmsman students”. The profiles included strength and vulnerability aspects of university students’ disposition and motivation to learn. The study also revealed interactions between the profiles and gender, educational level, and academic disciplines. These findings are discussed in relation to the current literature, as well as to theoretical and practical implications.

Environmental impact and efficiency of use of resources of different mountain dairy farming systems

In the European Alps traditional, low-input dairy farming systems still coexist with modern high-input intensive systems. This study aimed at evaluating the effect of different Alpine farming systems on the environmental footprint, production efficiency (gross energy conversion ratio, ECR) and competition between feed and food (potentially human-edible gross energy conversion ratio, HeECR). Data originated from 37 dairy farms located in the Trento province (eastern Italian Alps), from which four dairy systems were derived by performing non-hierarchical cluster analysis based on farm facilities and management features (traditional, either with tie or loose stalls, and intensive, either with or without use of silages, systems). Environmental footprint was computed using a cradle-to-farm gate Life Cycle Assessment model. One kg fat- and protein-corrected Milk (FPCM) and 1 m2 of agricultural land were used as functional units. Global warming (GWP), acidification (AP) and eutrophication (EP) potentials, cumulative energy demand (CED) and land occupation (LO) were included as impact categories. System boundaries included herd and manure management, on-farm feedstuffs production and purchased feedstuffs and materials. Mean impact values per 1 kg FPCM were 1.0 ± 0.3 kg CO2-eq (GWP), 21.1 ± 4.3 g SO2-eq. (AP), 6.3 ± 1.2 g PO4-eq. (EP), 5.0 ± 2.0 MJ (CED), 1.4 ± 0.5 m2/y (LO), whereas per 1 m2 were 0.8 ± 0.3 kg CO2-eq (GWP), 16.3 ± 4.2 g SO2-eq. (AP), 4.9 ± 1.3 g PO4-eq. (EP), 3.8 ± 1.8 MJ (CED). Mean ECR was 5.17 ± 0.89 MJ/MJ, with 88% of gross energy provided by non-human edible feedstuffs. A large variability was found both between and within dairy systems, in terms of environmental footprint and production efficiency. Impact values were slightly greater per unit of product and lower per unit of area in traditional than in intensive farms, although generally without significant differences. Production efficiency of traditional farms was 17% lower in terms of ECR but 59% greater in terms of HeECR, due to a lower proportion of purchased concentrates in animal rations, with a positive contribution to food balance and diet self-sufficiency. These results indicate that the transition from traditional towards intensive systems improved only slightly the environmental footprint of dairy farming, but increased markedly its dependence on external concentrate feeds and the feed-food competition. In perspective, different aspects of mountain dairy systems, such as the conversion into food of human non edible feeds, the low impacts at the local scale, the ability to conserve grasslands under a land-sharing perspective, and in general the associated ecosystem services, should be considered when aiming to improve their environmental sustainability.

Teachers' Patterns of Management of Conflicts With Students: A Study in Five European Countries.

The present study proposed an application of the Rahim’ Model of Conflict Management, and aimed to explore the styles of handling interpersonal conflicts with students adopted by teachers from five European countries (Italy, Spain, Germany, Belgium, Austria), identifying specific patterns and evaluating potential differences according to teachers' Gender, Age, Working Seniority and Country of belonging. Overall, 589 secondary school teachers completed a questionnaire consisting of Socio-demographic characteristics and the Rahim Organizational Conflict Inventory-II (ROCI-II, Form B). Non-hierarchical k-means cluster analysis was employed to derive patterns of conflict management, identifying four patterns labelled as Multi-strategic and Engaged, Multi-strategic and Solution-Oriented, Control-Oriented and Avoidant, and Mediating. Significant differences between countries were found in the numbers of teachers grouped across the four patterns. Findings identified stable and meaningful patterns for evaluating teachers' styles of management of interpersonal conflicts with students and for promoting teachers’ effectiveness in conflict management in the European school context.

Clinical characteristics of participants enrolled in an early identification and healthcare management program for dementia based on cluster analysis and the effectiveness of associated support efforts.

Although early identification and management services for dementia have become more widespread, their efficacy and the clinical characteristics of service have yet to be fully evaluated. Therefore, the objective of this study is to clarify these issues. The subjects were 164 Japanese users of an early identification and management program for dementia, known as the Initial-phase Intensive Support Team (IPIST), between 2013 and 2015. Nonhierarchical cluster analysis was used to derive subgroups based on cognitive status and ability in activities of daily living (ADL) and behavioral and psychological symptoms of dementia (BPSD). One-way analysis of variance was performed to evaluate differences among the groups derived by the cluster analysis. A paired t test was used to assess how the clinical status of the groups changed between baseline and follow-up. Four groups were identified by cluster analysis, i.e. a mild group, a moderate group, a BPSD group with moderate cognitive impairment and severe BPSD, and a severe group with severe cognitive impairment and severe BPSD. Although there were no significant improvements in cognitive impairment or ADL in any group, significant improvements were found in BPSD in the BPSD and severe BPSD groups. Caregiver burden was significantly lessened in all groups. Clinical diagnosis and long-term care insurance service utilization rates were significantly improved overall. The users of IPIST were classified into four subgroups based on their clinical characteristics. The IPIST program could improve the quality of life of people with dementia and their caregivers.

RESIDENTS' PERCEPTION TOWARDS TOURISM IN AN INDUSTRIAL BRAZILIAN CITY: A CLUSTER ANALYSIS

Joinville is the biggest city of Santa Catarina State (Brazil) and its main economic activity is industry. The service sector is expanding rapidly and tourism has been gaining momentum, especially regarding business and events. Although tourism is also an important economic activity, there were no studies about residents’ perception regarding it in Joinville (SC – Brazil) until now, hence the purpose of this study. We conducted 498 surveys with residents from every neighborhood in the city. The questionnaire had 20 questions. The data were tabulated, then we performed a non-hierarchical cluster analysis. We identified four clusters: Moderate Optimists, Optimists, Sceptics and Enthusiasts, the latter being the most representative. It was concluded that Joinville residents perceive tourism positively. On the other hand, tourism needs to be planned and needs a more effective promotion. This way, residents can have a better understanding of its economic, sociocultural and environmental benefits.

Data science in neurodegenerative disease: its capabilities, limitations, and perspectives.

Purpose of reviewWith the advancement of computational approaches and abundance of biomedical data, a broad range of neurodegenerative disease models have been developed. In this review, we argue that computational models can be both relevant and useful in neurodegenerative disease research and although the current established models have limitations in clinical practice, artificial intelligence has the potential to overcome deficiencies encountered by these models, which in turn can improve our understanding of disease.Recent findingsIn recent years, diverse computational approaches have been used to shed light on different aspects of neurodegenerative disease models. For example, linear and nonlinear mixed models, self-modeling regression, differential equation models, and event-based models have been applied to provide a better understanding of disease progression patterns and biomarker trajectories. Additionally, the Cox-regression technique, Bayesian network models, and deep-learning-based approaches have been used to predict the probability of future incidence of disease, whereas nonnegative matrix factorization, nonhierarchical cluster analysis, hierarchical agglomerative clustering, and deep-learning-based approaches have been employed to stratify patients based on their disease subtypes. Furthermore, the interpretation of neurodegenerative disease data is possible through knowledge-based models which use prior knowledge to complement data-driven analyses. These knowledge-based models can include pathway-centric approaches to establish pathways perturbed in a given condition, as well as disease-specific knowledge maps, which elucidate the mechanisms involved in a given disease. Collectively, these established models have revealed high granular details and insights into neurodegenerative disease models.SummaryIn conjunction with increasingly advanced computational approaches, a wide spectrum of neurodegenerative disease models, which can be broadly categorized into data-driven and knowledge-driven, have been developed. We review the state of the art data and knowledge-driven models and discuss the necessary steps which are vital to bring them into clinical application.

Application of Cluster Analysis in Building Retirement Wealth Adequacy Profile: A Case Study in Malaysia

This study aims to examine retirement wealth adequacy based on the underlying structure of households’ attributes from Household Expenses and Income Survey 2014 (HEIS14) data. In specific, the two-step cluster analysis is carried out to build the profiles that will be used to compute retirement wealth adequacy. In general, the data that contains both numerical and categorical variables do not suit well for pure hierarchical and non-hierarchical cluster analysis. To counter this issue, the twostep cluster analysis employs log-likelihood function to measure the distance between two clusters, where the numerical variables are assumed to follow a normal distribution, meanwhile categorical variables are assumed to follow the multinomial distribution. We have used Schwarz’s Bayesian Criterion (BIC) and Akaike’s Information Criterion (AIC) to determine the number of clusters to be formed. In addition, we employed a Silhouette measure of cohesion and separation to examine the overall goodness-of-fit. The analysis successfully generated a solution of three clusters. The first cluster represents households with the majority of SPM holders, receiving an average gross monthly salary of RM 5058.73 and working in the private sector. The second cluster represents households with the majority of diploma holder/professional certificate, receiving an average gross monthly salary of RM 10154.06 and most of them (92%) working in the private sector. The third cluster represents households who work in the public sector with an average gross monthly salary of RM 7185.74. From the microsimulation process, the results show that 51% of households in Cluster 1 have adequate retirement wealth, while only 13% of households in Cluster 3 have adequate retirement wealth.

Effect of work on body language of ranch horses in Brazil.

The horses’ responses to exercise are commonly monitored using physiological variables, nonetheless physical and mental states can also be expressed through body language. The aims of this study were: (i) to identify how facial expressions and other behavioural variables change in ranch horses after a routine workday, and (ii) to investigate if these changes can be used as indicators of physical tiredness by relating them to known variables of physical fitness and workload. Fourteen crossbred ranch horses were assessed pre- and post-workday on two farms, recording the body language, physiological and workload variables. Statistical analysis consisted of four stages: (i) comparisons between the sampling times (pre- vs post-workday) using linear mixed-effects models with repeated measures and a paired Wilcoxon test; (ii) selection of the most powerful variables by applying Kaiser-Meyer-Olkin test and principal components analyses (PCA); (iii) evaluations of the relationships within these selected variables utilizing PCA and Spearman rank coefficients; and (iv) identifying a critical level of the most robust behavioural indicators using a non-hierarchical cluster analysis. Results showed that after a workday the horses increased the frequency/duration of body language indicative of resting. They also decreased the frequency/duration of body language indicative of attention and movements to avoid flies. However, some of these behaviours are also shown when horses are in pain, leading us to suggest that some ranch horses were probably experiencing a combination of of tiredness and slight soreness. Of particular interest, because of the ease with which it can be assessed on the farm and generalized to other situations, we suggest that the frequency of shifting weight between the forelegs has potential to be used as an indicator of physical tiredness in horses. The results can also be used in the development of tools to improve the welfare of ranch horses as well as horses used in other activities, although more research is needed to validate this assumption.

An Exploratory Study of Financial Performance in CEE Countries

Our research investigates the performance of companies from Central and Eastern European (CEE) countries in the period after the Global Financial Crisis of 2007-2009 with the aim of identifying the driving factors behind accounting- and market-based performance. We include in the analysis companies from various industries in CEE countries that are European Union members and we study their performance between 2008-2016 over the following areas of performance: liquidity, solvency and indebtedness, operational profitability, global performance (through Return on assets and Return on equity), returns available to shareholders and market-based performance (through price/book value and Tobin Q ratio). Employing the hierarchical and non-hierarchical k-means cluster analysis companies are segmented into various homogeneous groups using various financial performance indicators as variables, Euclidian distances and the Ward amalgamation method. Furthermore, the resulting clusters have been grouped according to the country of origin and industry. Our findings show that specific groups of companies in these countries share common attributes, as evidenced by their performance indicators, which do not seem to be entirely based on their countries of origin and industry. Moreover, our exploration of CEE companies’ performance dynamics after 2008 evidences the increased competition in all industries particularly after 2009, as well as businesses’ need to adjust their activities after the losses incurred during the crisis period, but these phenomena is present with different intensities depending on country of origin and industry. At the same, we note the enhancement of global performance through improvements in the operational performance instead of financial leverage and indebtedness, which is a sound business approach by CEE companies.
 Keywords: financial performance, Central and Eastern Europe (CEE), statistical cluster analysis, return to investors

Húsfogyasztási szokások egy naplóíró kutatás tapasztalatai alapján

THE AIMS OF THE PAPER Meat is an important source of nutrient for Hungarian since considering food consumption meat is the fourth most important one. The aim of this study is to explore of eating habits and the role of meat in everyday life and to segment consumers based on meat consumption and snacking and to profile them based on socio-demographics. METHODOLOGY Ton answer the research questions the method of diary was used. Participant had to note their eating habits, what they ate, when and where and whether they snacked between meal times or not. The empirical research was conducted in April 2017 in the most developed regions of Hungary (Western Transdanubia: 66.7%, Central Transdanubia and Central Hungary: 33.3%). Altogether the data of 171 (66.7% females and 35.1% males) consumers were collected. To interpret the results uni- and multivariate statistical analysis was used. The connection between consumption and socio-demographics was analysed with the method of ANOVA. To segment consumers the methods of hierarchical (Ward’s method) and non-hierarchical cluster analyses (K-mean) were used. To profile each segment the multinominal logistic regression was conducted. MOST IMPORTANT RESULTS Lunch and dinner are the most important eating occasions among participants. Only a few people follow a healthy diet and eat five times a day. Meat is an important nutrition in every-day eating however females eat less than males. Snacking is also typical for Hungarian especially for those who have lower level of education. Cluster analysis was conducted based on the frequency of eating, meat consumption and snacking. Four consumer groups were identified: restrained meat eaters, conscious eaters, snack lovers and meat lovers. Restrained meat eaters are mainly females. Conscious eaters live in villages or towns like snack lovers who typically have lower level of education. RECOMMENDATIONS These results are useful for food especially meat industry to define their marketing program and product policy targeted at special audience. Acknowledgement: This work was supported by Szechenyi Istvan University and the Hungarian Government and the European Union within the European Structural and Investment Funds. This study was written as a part of a project entitled EFOP-3.6.1-16-2016-00017, “Internationalization, initiatives to establish a new source of researchers and graduates, and development of knowledge and technological transfer as instruments of intelligent specializations at Szechenyi University”.

Genetic divergence for qualitative traits of fruit yield and its components in custard apple (Annona squamosa L.). Indigenous accessions from northern Bastar of Chhattisgarh

The field experiment was conducted at Research cum Instructional Farm, College of Agriculture and Research Station, Singarbhat, Kanker, Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.) during Kharif 2013-14. The experiment was laid out in Randomized Block Complete Design with four replication, in-situ sixty genotypes of about 10 year age were selected for investigation, which were found as wild seedling plants on forest land and rice bunds in Kanker District-(C.G.). The treatments comprised of sixty genotypes for with different qualitative character viz total soluble solid, total sugar, reducing sugar, non-reducing sugar, titration acetic acid, keeping days, pulp ratio, pulp seed ratio, peel percentage and fruit yield per plant. The D2 analysis classifies the genotypes into relatively homogeneous groups in such a way that within cluster diversity is minimized and between clusters diversity is maximized. The respective genotypes from diverse clusters can be utilized in breeding programme. Cluster analysis for qualitative traits showed that all genotypes were grouped into 8 clusters using non-hierarchical Euclidean cluster analysis (Table 4.15 and Fig. 4.5). For qualitative parameter, maximum number of genotypes were grouped into cluster VIII (14) followed by cluster III (12). Intra and Inter-Cluster distances among 8 clusters for qualitative traits in custard apple are presented in Table 4.16. The highest intra-cluster distance was recorded for cluster VI (48.65) followed by cluster II (46.79) and the smallest intra cluster distance was recorded in cluster III (0.00) followed by cluster V (8.15) for qualitative traits. Custard apple is a predominantly cross-pollinated (protogyny) crop and no information is available suggesting a change in its breeding behavior under varied environmental conditions. Discrimination of desirable parents for a successful hybridization programme is a difficult task for a plant breeder. Generally, geographical diversity has been considered as a measure of genetic diversity. However, this is an inferential criterion and it may not be so effective in quantifying or differentiating among populations.

Challenge-Oriented Behavior Types: A New Explanation

The purpose of this study is to broaden theoretical meaning of challenge and attain a place for its practical use in schools. Based on the purpose, a theoretical construct was developed to explain four types of challenge-oriented behavior: (a) creators, (b) choosers, (c) maintainers and (d) avoiders. 634 fifth-, sixth- and seventh-grade students in Istanbul, Turkey, participated in the study. The Challenge-Oriented Behavior Scale and the Challenge-Performance Test were the main instruments. The Challenge-Oriented Behavior Scale scores were subjected to non-hierarchical cluster analyses, which revealed four profiles. To gain ecological validity of the current understanding, an alternative method, reverse-action strategy was developed. The aim was to explain how actual student performance is defined by self-perceived challenge-orientation type. To this respect, the Challenge-Performance Test scores and other factors were examined using path analysis. The findings suggest that demonstrated performance in pursuing challenges arise from past experience, academic achievement, self-perceived challenge-orientation type and age.

An investigation on conceptual understanding about cosmology

AbstractIn this study, we identify patterns among students beliefs and ideas in cosmology, in order to frame meaningful and more effective teaching activities in this amazing content area. We involve a convenience sample of 432 high school students. We analyze students’ responses to an open-ended questionnaire with a non-hierarchical cluster analysis using the k-means algorithm.

The direction of urban development and policy implications for response to climate change – the case of Gwangju Metropolitan City, Republic of Korea

ABSTRACTThis study investigates the case of Gwangju Metropolitan City, which has been developing preemptive policies to cope with the impact of climate change. It is necessary and important to examine empirical data on how Gwangju Metropolitan City has promoted its preemptive response to climate change. The concept of climate change, the status of climate change, and the energy consumption of each sector were first identified, and trends and prospects of changes in traffic conditions, and the status of parks and green spaces were examined using indicators from a 10 year period (2002–2011). Relevant variables were selected from the climate carbon map constituents presented in the ‘2030 Gwangju Metropolitan City Master Plan’ report, and key urban indicators and low-carbon indicators presented in ‘A Study on the Construction of Climate Carbon Map in Gwangju’. Cluster analysis using the factor scores of the factors extracted through these variables, followed by principal component analysis and k­medians nonhierarchical cluster analysis, were carried out using STATA 11.1. Thereafter, SWOT analysis was performed to classify the environmental factors (strengths and weaknesses) and external environmental factors (opportunities and threats) into categories based on the variables extracted from Gwangju Metropolitan City’s response to climate change. The purpose of this study is therefore to classify the above-mentioned trends in urban development responses to climate change into factorization types classified by principal component analysis, and to analyse the results of SWOT analysis and factors that can mitigate the urban heat island phenomenon based on the derived factors and the development of public transit-oriented urban development (TOD). This study serves not only as basic research data in presenting urban development strategies for future climate change, but also suggests policy implications.

CLASIFICACIÓN DE ESTUDIANTES DE ENFERMERÍA MEXICANOS ACORDE CON UN INDICADOR DE ESTILO DE VIDA SALUDABLE

Objective: To describe groups of Nursing students according to a healthy lifestyle index. Material and method: Exploratory and quantitative study, conducted at the Universidad Autonoma del Estado de Mexico (UAEM). The sample consisted of 865 Nursing students. A non-hierarchical cluster analysis was made using k-means with a partition in three groups, which represent the lifestyle index. Results: Three clusters representing the student’s lifestyle index were distinguished: poor healthy lifestyle (n=392), healthy lifestyle (n=402) and veryhealthy lifestyle (n=71). Stress, smoking and drinking, are the most common risk behaviours among students. Conclusion: A large number of Nursing students were grouped in the poor healthy lifestyle cluster. Therefore, it is necessary to promote healthy lifestyles in university settings.

A synthetic approach for assessing the interplay of form and function in the crocodyliform snout

Abstract Existing classifications of snout shape within Crocodylia are supported by functional studies, but ecological surveys often reveal a higher than expected diversity of prey items within putatively specialist groups, and research into bite force and predation behaviour does not always reveal significant differences between snout shape groups. The addition of more distantly related crocodyliforms complicates the ecomorphological signal, because these groups often occupy a larger area of morphospace than the crown group alone. Here, we present an expanded classification of snout shapes and diets across Crocodyliformes, bringing together geometric morphometrics, non-hierarchical cluster analyses, phylogenetic analyses, ancestral state reconstructions, ecological surveys of diet, and feeding traces from the fossil record to build and test predictive models for linking snout shape and function across the clade. When applied to living members of the group, these new classifications partition out based on differences in predator body mass and maximal prey size. When applied to fossils, these classifications predict potential prey items and identify possible examples of scavenging. In a phylogenetic context, these ecomorphs reveal differences in dietary strategies and diversity within major crocodyliform clades. Taken together, these patterns suggest that crocodyliform diversity, in terms of both morphology and diet, has been underestimated.

Overcoming the unitary exploration of binge-watching: A cluster analytical approach.

Background and aimsBinge-watching (i.e., watching multiple episodes of a TV series in one session) has recently become standard practice among TV series viewers; this expansion generates concerns regarding the potential negative outcomes associated with this habit. However, the investigation of its psychological correlates remains fragmentary, with few initial studies a priori conceptualizing this behavior as a new addictive disorder. This study explored these psychological correlates using cluster analysis of binge-watching behavior based on three key psychological factors: motivations, impulsivity, and emotional reactivity.MethodsAn online survey was completed by 4,039 TV series viewers. Data were analyzed using hierarchical and non-hierarchical cluster analyses, the validity of the clusters being finally determined through mutual comparisons with a selection of external correlates.ResultsFour clusters were identified: recreational TV series viewers (presenting low involvement in binge-watching), regulated binge-watchers (moderately involved), avid binge-watchers (presenting elevated but non-problematic involvement), and unregulated binge-watchers (presenting potentially problematic involvement associated with negative outcomes).Discussion and conclusionsThis study underlines the heterogeneous and multidetermined nature of binge-watching. Our findings suggest that high engagement in binge-watching is distinct from problematic binge-watching, thus reinforcing the notion that conceptualizing binge-watching as an addictive disorder is of low relevance and might actually lead to the overpathologization of this highly popular leisure activity.

Biogenic amines profile in red wines regarding aging and storage conditions

The determination and quantification of eight biogenic amines in red wines without sample clean-up has been carried out by an ultra-high performance chromatographic method with fluorescent detection based on the o-phthaldialdehyde derivatization reaction. In these conditions, several monovarietal ‘Tempranillo’ wines (young, oak and aged ones) have been analyzed and the total concentrations of biogenic amines ranged between 22.2 and 73.4 mg L−1, which is in concordance with other Spanish red wines. No significant differences of total biogenic amines content between young and oak wines have been observed, but total biogenic amines content in aged wine is significant different. A study of the influence of the storage conditions through time has been carried out with three types of wine (young, oak and aged wine). Principal Components Analysis (without and with Varimax rotation) and hierarchical and non-hierarchical cluster analysis grouped the samples by wine aging. On the other hand, Discriminant Analysis allowed to classify the observations of each wine by storage time and conditions (storage temperature and bottle closing).

The application of geometric models for the study of hydrological regime of protected shallows in reservoirs

This study considers the possibility of using geometric models in the study of individual elements of hydrological regime in different types of protected shallows in the Upper Volga reservoirs. Three types of models were chosen and verified. The formulas for calculating the bathygraphic curves of geometric figures approximating the beds of protected shallows are determined. Classes with different morphometric characteristics are identified using non-hierarchical cluster analysis for each type of shallows. Model calculations of areas and volumes of shallows are carried out depending on seasonal changes in water level, as well as estimates of thermal content, average monthly water balance and water exchange in the shallows.