scholarly journals Towards Understanding Clustering Problems and Algorithms: An Instance Space Analysis

Algorithms ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 95
Author(s):  
Luiz Henrique dos Santos Fernandes ◽  
Ana Carolina Lorena ◽  
Kate Smith-Miles
Keyword(s):  
Clustering Algorithms ◽  
Space Analysis ◽  
Meta Learning ◽  
Instance Space ◽  
Meta Analyses ◽  
The Impact ◽  
First Time ◽  
The Relationship ◽  
Clustering Problems ◽  
Selection Of

Various criteria and algorithms can be used for clustering, leading to very distinct outcomes and potential biases towards datasets with certain structures. More generally, the selection of the most effective algorithm to be applied for a given dataset, based on its characteristics, is a problem that has been largely studied in the field of meta-learning. Recent advances in the form of a new methodology known as Instance Space Analysis provide an opportunity to extend such meta-analyses to gain greater visual insights of the relationship between datasets’ characteristics and the performance of different algorithms. The aim of this study is to perform an Instance Space Analysis for the first time for clustering problems and algorithms. As a result, we are able to analyze the impact of the choice of the test instances employed, and the strengths and weaknesses of some popular clustering algorithms, for datasets with different structures.

scholarly journals The Impact of Alkaloid-Producing Epichloë Endophyte on Forage Ryegrass Breeding: A New Zealand Perspective

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 158
Author(s):  
Colin Eady
Keyword(s):  
Seed Production ◽  
Health Issues ◽  
Abiotic Stressors ◽  
Livestock Health ◽  
The Right ◽  
The Impact ◽  
The Relationship ◽  
And Storage ◽  
Selection Of ◽  
Epichloë Endophyte

For 30 years, forage ryegrass breeding has known that the germplasm may contain a maternally inherited symbiotic Epichloë endophyte. These endophytes produce a suite of secondary alkaloid compounds, dependent upon strain. Many produce ergot and other alkaloids, which are associated with both insect deterrence and livestock health issues. The levels of alkaloids and other endophyte characteristics are influenced by strain, host germplasm, and environmental conditions. Some strains in the right host germplasm can confer an advantage over biotic and abiotic stressors, thus acting as a maternally inherited desirable ‘trait’. Through seed production, these mutualistic endophytes do not transmit into 100% of the crop seed and are less vigorous than the grass seed itself. This causes stability and longevity issues for seed production and storage should the ‘trait’ be desired in the germplasm. This makes understanding the precise nature of the relationship vitally important to the plant breeder. These Epichloë endophytes cannot be ‘bred’ in the conventional sense, as they are asexual. Instead, the breeder may modulate endophyte characteristics through selection of host germplasm, a sort of breeding by proxy. This article explores, from a forage seed company perspective, the issues that endophyte characteristics and breeding them by proxy have on ryegrass breeding, and outlines the methods used to assess the ‘trait’, and the application of these through the breeding, production, and deployment processes. Finally, this article investigates opportunities for enhancing the utilisation of alkaloid-producing endophytes within pastures, with a focus on balancing alkaloid levels to further enhance pest deterrence and improving livestock outcomes.

Render unto Caesar Just a Little Bit Longer: The Relationship between Constitutional Reforms and Executive Survival

2021 ◽  
pp. 1-22
Author(s):  
Tofigh Maboudi ◽  
Ghazal P. Nadi ◽  
Todd A. Eisenstadt
Keyword(s):  
Term Limits ◽  
Institutional Constraints ◽  
Third Wave ◽  
Political Leaders ◽  
Constitutional Order ◽  
The Third ◽  
Constitutional Reforms ◽  
The Impact ◽  
First Time ◽  
The Relationship

Abstract Since the third wave of democracy, term limits have become a popular fixture of most constitutions intended to constrain the executive. Yet, recent constitutional reforms around the world show that presidents seeking re-election sometimes overturn the entire constitutional order to extend their power. What is the impact of these constitutional manipulations on the longevity of the executive in office? Using survival analysis of all political leaders and national constitutions from 1875 to 2015, this article demonstrates, for the first time, that when ‘authoritarian-aspiring’ presidents remove constitutional term limits, they increase their stay in office by more than 40%. Our findings contrast with a widely held position in the comparative authoritarian literature suggesting that dictators survive longer under institutional constraints. On the contrary, we argue that by removing constitutional barriers, rulers consolidate more power at the expense of their most ambitious allies and can stay in power longer.

scholarly journals Comments on "Researcher bias: The use of machine learning in software defect prediction"

2015 ◽  
Author(s):  
Chakkrit Tantithamthavorn ◽  
Shane McIntosh ◽  
Ahmed E Hassan ◽  
Kenichi Matsumoto
Keyword(s):  
Prediction Model ◽  
Strong Association ◽  
Model Performance ◽  
Strong Relationship ◽  
Defect Prediction ◽  
Explanatory Variables ◽  
Software Defect ◽  
The Impact ◽  
The Relationship ◽  
Selection Of

Shepperd et al. (2014) find that the reported performance of a defect prediction model shares a strong relationship with the group of researchers who construct the models. In this paper, we perform an alternative investigation of Shepperd et al. (2014)’s data. We observe that (a) researcher group shares a strong association with the dataset and metric families that are used to build a model; (b) the strong association among the explanatory variables introduces a large amount of interference when interpreting the impact of the researcher group on model performance; and (c) after mitigating the interference, we find that the researcher group has a smaller impact than the metric family. These observations lead us to conclude that the relationship between the researcher group and the performance of a defect prediction model may have more to do with the tendency of researchers to reuse experimental components (e.g., datasets and metrics). We recommend that researchers experiment with a broader selection of datasets and metrics to combat potential bias in their results.

scholarly journals The Design, Content and Delivery of Relationship and Sexuality Education Programmes for People with Intellectual Disabilities: A Systematic Review of the International Evidence

2020 ◽  
Vol 17 (20) ◽  
pp. 7568
Author(s):  
Michael Brown ◽  
Edward McCann ◽  
Maria Truesdale ◽  
Mark Linden ◽  
Lynne Marsh
Keyword(s):  
Intellectual Disabilities ◽  
Sexuality Education ◽  
Inclusion Criteria ◽  
Quality Appraisal ◽  
Programme Development ◽  
People With Intellectual Disabilities ◽  
Adults With Intellectual Disabilities ◽  
Meta Analyses ◽  
The Impact ◽  
The Relationship

There is growing empirical evidence regarding the relationship and sexuality experiences and needs of children, young people and adults with intellectual disabilities. A total of twelve papers met the inclusion criteria regarding relationship and sexuality education (RSE) programmes specific to the needs of this population. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed and quality appraisal undertaken. The four themes identified were principles informing RSE programme development, design and content of RSE programmes, delivery of RSE programmes and evaluation of RSE programmes. The discussion presents areas that need to be addressed to ensure that people with intellectual disabilities, their families, carers and professionals are fully involved in the design and delivery of RSE programmes. Further research is required to identify the impact of the programmes and the sustained outcomes achieved. Recommendations are made regarding the activities required to enable the development of evidence-based and person-centred approaches to relationship and sexuality programmes.

Evolution of Drosophila insecticide resistance

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 1-7 ◽  
Author(s):  
R. A. Morton
Keyword(s):  
Insecticide Resistance ◽  
Quantitative Traits ◽  
Molecular Genetic ◽  
Resistance Evolution ◽  
Target Molecules ◽  
Genetic Techniques ◽  
The Cost ◽  
The Impact ◽  
The Relationship ◽  
Selection Of

The impact of insecticide resistance is well documented. It includes the toxic effects of pesticides on the environment and the cost of the increased amounts of insecticides required to effectively control resistant insects. Resistance evolves by the selection of genes that confer tolerance to insecticides. Several resistance genes have been identified and cloned in Drosophila, including genes for mutant target molecules and genes that increase insecticide degradation. Drosophila is a useful system to understand the evolution of quantitative traits in general as well as the population genetics of insecticide resistance. Through it, we may hope to understand the relationship between discrete genetic change and continuously varying characters. In addition, molecular genetic techniques developed using Drosophila can eventually be transferred to other insects in order to help control pest populations.Key words: insecticide resistance, evolution of tolerance, selection of resistant genes, molecular genetics, Drosophila.

scholarly journals The Grain Market between the Reigns of Alexey Mikhailovich and Catherine the Great: Was there a ‘Price Revolution’?

2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Arthur Mustafin
Keyword(s):  
Eighteenth Century ◽  
Supply And Demand ◽  
Wide Range ◽  
Grain Market ◽  
The Impact ◽  
First Time ◽  
The Relationship ◽  
Regions Of Russia ◽  
Grain Prices

The author of this article attempts to reveal and systematise archival data on grain prices in Russia between the 1650s and 1700s and analyse their dynamics by comparing them with data for the eighteenth century. The study is based on a wide range of archival sources from the funds of the RSAAA (RGADA), CSA of Moscow (TsGA of Moscow), DM NLR (OR RNB), and SFI CANNR (GKU TsANO). The data from these sources make it possible to construct time series describing rye and oat price dynamics in the northern and central non-black earth regions of Russia. The author substantiates the homogeneity and reliability of the data received and determines the real prices. The resulting numbers make the author doubt the “price revolution” in eighteenth-century Russia. Throughout the eighteenth century, the average real prices remained below the level of the 1660s and 1670s. Only in the 1790s did prices briefly exceed this level. Overall, the Russian grain market was characterised by long-term price fluctuations. The author aims to explain this dynamic by analysing supply and demand in the grain market. More particularly, for the first time in the historiography, the author examines the connection between Russian grain prices and yield in the second half of the seventeenth and eighteenth centuries. It is established that in most cases, the relationship between these indicators was direct: as grain yield increased, prices did too. The article explains this seeming paradox. The data published by the author help not only to estimate the impact of various factors on grain prices during the period in question, but also solve practical tasks regarding various price indicators in grain equivalents.

scholarly journals The relationship between diet, energy balance and fertility in men

2020 ◽  
Vol 90 (5-6) ◽  
pp. 514-526 ◽  
Author(s):  
Edyta Suliga ◽  
Stanisław Głuszek
Keyword(s):  
Energy Balance ◽  
Male Fertility ◽  
Sperm Count ◽  
Direct Analysis ◽  
Reproductive Hormones ◽  
Semen Parameters ◽  
The Right ◽  
Meta Analyses ◽  
The Impact ◽  
The Relationship

Abstract. Research conducted in recent years provides more and more evidence that diet can have a significant impact on male fertility. The aim of the study was to analyze the relationship between diet, energy balance and fertility in men. A comprehensive literature search of published studies in various languages, was carried out in electronic databases. The direct analysis included 96 works published between 2008 and 2018, including 12 randomized controlled trials and 23 systematic reviews and meta-analyses. A strong adherence to a healthy dietary pattern is positively correlated with total sperm count, progressive motility and total motile sperm count (all p < 0.05). However, attention is drawn to the fact that foods that are considered “healthy” can sometimes contain a significant amount of pollution, which negatively affect the semen parameters. An adequate intake of antioxidants or their supplementation have been quite effective in the prevention and treatment of male infertility. The improvement of pregnancy rate after antioxidant therapy ranged in various studies from 11% to 41%. An important problem, however, may be choosing the right dose of the supplement or finding an appropriate combination of antioxidants that may be more effective than any single antioxidant. The normalization of men’s body weight is beneficial for the quality of sperm and the concentration of male reproductive hormones. Further, long-term studies require the assessment of the impact of drastic weight loss after bariatric surgery on male fertility.

scholarly journals Η συμβολή των μεταναστών στην ελληνική οικονομία: Mετά-ανάλυση των εμπειρικών ευρημάτων

2016 ◽  
Vol 8 (2) ◽  
Author(s):  
Θεόδωρος Μητράκος
Keyword(s):  
Survey Design ◽  
Effect Sizes ◽  
Empirical Literature ◽  
Probit Models ◽  
Comparable Effect ◽  
Study Characteristics ◽  
Greek Economy ◽  
Meta Analyses ◽  
The Impact ◽  
The Relationship

This study synthesizes the findings of the empirical literature available by means of meta-analyses of the impact of immigration on the Greek economy in order to detect whether consensus conclusions are emerging and whether differences in results across studies can be explained. For this purpose, the study recodes the contribution of migrants to the Greek economy and the labour market resulting from the available studies as benefiting or harming the Greek economy and native born, and estimates alternative probit and order probit models to assess the relationship between this observed impact and key study characteristics such as methodology, period of investigation, survey design, publication year etc. Even if the sample of studies available to generate comparable effect sizes remains severely limited by the heterogeneity in different approaches, the study shows that the contribution of immigrants in terms of economic growth, wages and employment is clearly positive, although rather relatively small.

scholarly journals Peculiarities of selecting woody plants for anatomy analysis in various environments

2021 ◽  
Vol 946 (1) ◽  
pp. 012048
Author(s):  
I I Vlasova ◽  
A V Kopanina
Keyword(s):  
Woody Plants ◽  
Woody Plant ◽  
Sampling Area ◽  
Geological Processes ◽  
Plant Samples ◽  
Bark Tissue ◽  
Wood Analysis ◽  
The Impact ◽  
First Time ◽  
Selection Of

Abstract Methods for studying woody plants anatomy are now very diverse. We modified the guidelines for bark studies developed for wood analysis at all stages of preparing the woody plant samples for microscope study. For the first time, we used separation to separate hard and soft fractions of the bark tissue. Correct approach to selection of plant samples and further laboratory manipulations ensures validity of the results of our study. We select the size of the sampling area depending on the type of vegetation. In every habitat, we also include transects along the gradient of height above sea level or the impact from the source of natural stress. The results of our research will help study landscape changes during exogenous geological processes and phenomena using biological indication of geosystems.

scholarly journals Trade unions and the economic performance of brazilian establishments

2008 ◽  
Vol 38 (1) ◽  
pp. 55-72 ◽  
Author(s):  
Naércio Aquino Menezes-Filho ◽  
José Paulo Chahad ◽  
Hélio Zylberstajn ◽  
Elaine Toldo Pazello
Keyword(s):  
Economic Performance ◽  
Performance Indicators ◽  
Trade Unions ◽  
Manufacturing Sector ◽  
Profit Sharing ◽  
Pooled Data ◽  
Low Levels ◽  
The Impact ◽  
First Time ◽  
The Relationship

This paper examines, for the first time in the literature, the impact of trade unions on various performance indicators of Brazilian establishments. A unionism retrospective survey was carried out among 1,000 establishments in the manufacturing sector and its results were matched to performance indicators available from the Brazilian Industrial Surveys between 1990 and 2000. The results using the pooled data indicate that the relationship between unionism and some performance indicators, such as average wages, employment and productivity is non-linear (concave), so that a rise in unionism from low levels is associated with higher performance, but at a decreasing rate. Unions also reduce profitability. Establishments that introduced profit-sharing schemes increased their productivity and profitability overall and paid higher wages in more unionized plants.

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