Single Linkage Cluster Research Articles

Micro-morphological study of three members of genus <i>Plectranthus</i> L. (Lamiaceae) in Nigeria

Micro-morphological studies of three members of the Genus Plectranthus L. (Lamiaceae) in Nigeria were conducted to investigate the anatomical characteristics of taxonomic importance. The following plant samples were collected from various locations in Southwestern Nigeria, namely Plectranthus aegyptiacus (Forssk.) C. Chr., Plectranthus esculentus N.E.Br. and Plectranthus monostachyus (P. Beauv.) B. J. Pollard. The anatomical study of the lamina epidermis, venation pattern and petiole were performed. The Single Linkage Cluster Analysis (SLCA) and one-way Analysis of Variance (ANOVA) with the Duncan Multiple Range Test (DMRT) were used to analyze the parameters, and photomicrographs were employed to document the observations. Foliar epidermal characteristics such as epidermal cell shape, anticlinal wall pattern, stomata types, trichome types and ergastic substances are essential in delimiting the species. The identification of numerous starch grains delimits P. monostachyus from the other species, a straight anticlinal wall pattern delimits P. esculentus, and the presence of abundant crystal sands delimits P. aegyptiacus. Quantitatively, stomata index (S.I.) and trichome length for both adaxial and abaxial surfaces were significantly different (P≤0.05) among the species. The venation pattern of the studied plant samples also revealed specific characteristics. Irregular vein spacing, eucamptodromous secondary vein category and polygonal areole shape delimit P. esculentus from the other species.

A genetically related cluster of Salmonella Typhimurium cases in humans associated with ruminant livestock and related food chains, United Kingdom, August 2021-December 2022.

Following an outbreak of Salmonella Typhimurium in Wales in July 2021 associated with sheep meat and offal, further genetically related cases were detected across the UK. Cases were UK residents with laboratory-confirmed Salmonella Typhimurium in the same 5-single-nucleotide polymorphism (SNP) single-linkage cluster with specimen date between 01/08/2021-2031/12/2022. We described cases using routine (UK) and enhanced (Wales only) surveillance data. Exposures in cases in Wales were compared with non-Typhimurium Salmonella case-controls. Environmental Health Practitioners and the Food Standards Agency investigated supply chains of food premises reported by ≥2 cases. Animal, carcass, and environmental samples taken for diagnostic or monitoring purposes for gastrointestinal pathogens were included in microbiological investigations. We identified 142 cases: 75% in England, 23% in Wales and 3% in Scotland. Median age was 32years, and 59% were male. Direct contact with sheep was associated with becoming a case (aOR: 14, 95%CI: 1.4-145) but reported by few (6/32 cases). No single food item, premises, or supplier linked all cases. Multi-agency collaboration enabled the identification of isolates in the same 5-SNP single-linkage cluster from a sheep carcass at an English abattoir and in ruminant, wildlife, poultry, and environmental samples, suggesting multiple vehicles and pathways of infection.

Phylogenetic analysis of Aciagrion Selys (Odonata: Coenagrionidae)

ABSTRACT Odonates are useful biological indicators of environmental health because of their pollution-free habitat requirements and amphibiotic life cycle. Due to habitat destruction by industrial development, there is a need to name these odonates and obtain their genetic data to be used in understanding their evolutionary history for biodiversity conservation. Aciagrion is a poorly known and taxonomically difficult genus of oriental damselflies. Species of this genus cannot be distinguished on the basis of morphological characters alone as they are morphologically similar to the damselflies of other genera (Ischnura and Amphiallagma) and may also be referred to as cryptic species. Here, therefore, molecular studies are carried out to distinguish the species of this genus. The phylogenetic relationships of five species of genus Aciagrion have been explored using molecular (based on concatenated sequences of mitochondrial genes- COI, ND1 and 16S rRNA genes) as well as external morphological characters. Single-linkage cluster analysis of morphological data sets did not explain the relationships appropriately among the species of this genus as outgroup species were also retrieved within ingroup species. Interspecific genetic divergence, conserved, variable, parsimony-informative sites, nucleotide base composition and transition/transversion bias based on concatenated gene sequences have been calculated for these species. It is found that a multigene concatenation approach interprets phylogeny more appropriately than the morphological data alone. Presently, a COI gene fragment sequence for one species (the endemic Aciagrion hisopa), 16S rRNA gene fragments for four species and ND1 gene fragments for five species have been submitted for the first time to GenBank, and phylogenetic relationships based on three genes have also been determined for the first time. Aciagrion migratum is a new record from India.

Molecular Characterization of Fluted Pumpkin Landraces in South East Nigeria

The fluted pumpkin Telfairia occidentalis (Hook F.) is a very important vegetable, popularly cultivated in South Eastern Nigeria for its economic value and its role in nutrition. It exhibits a high degree of interspecies variability and as such enhances biodiversity. Twenty landraces of fluted pumpkin were collected from five States in southern Nigeria which include; Anambra, Ogun, Lagos, Ondo and Enugu State. The landraces were grown in the Botanical Garden of Lagos State University, Ojo during the rainy season of 2013 for phenotypic screening to determine genetic divergence. The experiment was laid out in randomized block design with three replications. Genetic characterization was conducted in the biotech lab of the national institute of medical research (NIMER). The genomic DNA was extracted from the samples and extracted DNA samples were amplified through the PCR techniques using four primers (RAPD – 01, OPR-02, OPC – 04 and SCAR-1 primer) to access diversity among the genotypes. The result reveals a huge genetic divergence among the genotypes studied. The genotypes were grouped into five clusters based on a 2.0(20%) level of similarity by single linkage cluster analysis, which agrees with morphological data, each containing fluted pumpkin genotypes sharing common properties and being similar to one another.

Multivariate analysis of phenotypic variation and inter-character association in eggplant (Solanum melongena L.) accessions

The agronomic and nutritional values of eggplant (Solanum melongena) can be increased by harnessing its genetic variability. In this work, we aimed to study the variation and inter-character association among eggplant genotypes, with the ultimate goal of identifying genotypes that are useful for breeding. The study was carried out at the Federal University of Agriculture, Abeokuta, Nigeria in 2013, using seven eggplant genotypes. Data were collected on seventeen agro-morphological characters and subjected to principal component analysis (PCA), single linkage cluster analysis (SLCA), correlation analysis, and Genotype × Yield-Trait-biplot (GYT-biplot) procedure. PCA revealed that plant, fruit and yield characters were relevant in discriminating the genotypes while SLCA classified the genotypes into four clusters. Correlation analyses revealed a strong, significant but negative correlation between fruit breadth and yield traits while the GYT-biplot procedure delineated the genotypes into three sectors. We suggest that reduced fruit breadth should be selected for in order to obtain improved yield in eggplant. Genotypes 10014-101a, 97068-091a, and 12078-092e should be further investigated because they are in distinct clusters and, they are the vertex genotypes in sectors 1, 2 and 3.

Vegetative morphological study of selected species of genera Kalanchoe Adans. and Bryophyllum Salisb. (subfamily Kalanchoideae) from South Western Nigeria

A qualitative and quantitative morphological study of the three species of Bryophyllum and two Kalanchoe species in the subfamily Kalanchoideae was carried out to find out characters that may be useful in the identification, classification and also to solve some taxonomic problems within the subfamily Kalanchoideae. Vegetative parts from the various species were collected and subjected to morphological studies. Both qualitative and quantitative characters were recorded. Quantitative data were subjected to the least significance difference test (LSD), single linkage cluster analysis (SLCA) and principal components analysis (PCA). Unifying and diagnostic characters that are of taxonomic importance were recorded. The unifying characters propose that two genera in the Subfamily Kalanchoideae should be merged into a genus Kalanchoe with sections or subgenera under it.

Outbreak of sexually transmitted, extensively drug-resistant Shigella sonnei in the UK, 2021–22: a descriptive epidemiological study

Shigellosis, traditionally a foodborne and waterborne infection, causes substantial morbidity globally. It is now a leading cause of sexually transmitted gastroenteritis among gay, bisexual, and other men who have sex with men (MSM). We describe an ongoing outbreak of extensively drug-resistant (XDR) Shigella sonnei in the UK. Routine laboratory surveillance (Second Generation Surveillance System, Gastrointestinal Data Warehouse) identified an exceedance of S sonnei clade 5 in England, first detected in September, 2021. Cases within this clade were subsequently reported from Scotland, Wales, and Northern Ireland. Confirmed cases in this outbreak were defined as individuals diagnosed with S sonnei clade 5 in the UK, with a specimen date between Sept 1, 2021, and Feb 9, 2022, who were genomically confirmed as part of a ten-single nucleotide polymorphism (SNP) linkage cluster. We used whole-genome sequencing with SNP typing to identify genomic clusters and antimicrobial-resistance determinants, analysing cases across the UK. We collected demographic, epidemiological, and clinical data from people infected with S sonnei clade 5 in England using questionnaires (standard and bespoke outbreak questionnaires). We used descriptive summary statistics to characterise cases. 72 cases (70 [97%] male, median age 34 years [IQR 27-39]) belonging to the ten-SNP single linkage cluster of S sonnei clade 5 were identified between Sept 4, 2021, and Feb 9, 2022. Isolates were predominantly XDR, with 66 (92%) of 72 harbouring bla_CTX-M-27, a plasmid-mediated gene for production of extended-spectrum β-lactamases (ESBLs). Of 33 cases with clinical data, 19 (58%) received antibiotics and eight (24%) were hospitalised. 21 (78%) of 27 cases with completed bespoke outbreak questionnaires were HIV-negative MSM taking HIV pre-exposure prophylaxis (PrEP) who reported sexual contacts in the UK and Europe within the incubation period. We highlight the rapid dissemination of XDR ESBL-producing S sonnei in sexual networks of MSM. We recommend strengthening shigella testing where clinically indicated, antimicrobial-resistance surveillance, and integrated health promotion messaging among all MSM, including PrEP users, to reduce the burden of shigellosis. National Institute for Health Research Health Protection Research Unit in Gastrointestinal Infections at the University of Liverpool in partnership with the UK Health Security Agency.

Performance and character contributions to variability in okra (Abelmoschus esculentus L. Moench) genotypes

Abstract Okra is an important vegetable crop, but its optimal production is constrained by a myriad of problems including pests, poor agronomic practices, and improper varietal identification among others. A study was carried out to determine the field performance and contribution of agronomic characters to overall variation in eighteen okra genotypes over two locations, Teaching and Research Farms of the Federal University of Agriculture, Abeokuta, Nigeria and Rehoboth Farms Limited, Moniya, Ibadan, Nigeria. The experiments were laid down in a randomized complete block design with three replicates and data were collected on number of days to emergence, number of days to 50% flowering, number of branches per plant, pod length, pod width, number of pods per plant, plant height, pod weight, number of seeds per pod, number of ridges per pod, 100 seed weight, seed, and pod yield. The data were subjected to analysis of variance, heritability in the broad sense, principal component analysis as well as the single linkage cluster analysis. Results revealed significant (p <0.05) variation in the genotypes and high heritability estimates for most of the characters. Number of branches per plant, plant height, number of pods per plant accounted for the highest contributor to variations in the accessions while clustering analysis revealed genotypes; NGB00303, NGB00342 and NGB00346 were distant from all genotypes making them useful materials for hybridization studies.

Genetic Diversity Assessment in Dolichos Bean (Lablab purpureus L.) Based on Principal Component Analysis and Single Linkage Cluster Analysis

Background: Dolichos bean occupies a unique position among the legume vegetables of Indian origin for its high nutritive value and wider climatic adaptability. Despite its wide genetic diversity, no much effort has been undertaken towards genetic improvement of this vegetable crop. Knowledge on genetic variability is an essential pre-requisite as hybrid between two diverse parental lines generates broad spectrum of variability in segregating population. The current study aims to assess the genetic diversity in dolichos genotypes to make an effective selection for yield improvement.Methods: Twenty genotypes collected from different regions were evaluated during year 2016-17 and 2017-18. Data on twelve quantitative traits was analysed using principal component analysis and single linkage cluster analysis for estimation of genetic diversity.Result: Principal component analysis revealed that first five principal components possessed Eigen value greater than 1, cumulatively contributed greater than 82.53% of total variability. The characters positively contributing towards PC-I to PC-V may be considered for dolichos improvement programme as they are major traits involved in genetic variation of pod yield. All genotypes were grouped into three clusters showing non parallelism between geographic and genetic diversity. Cluster-I was best for earliness and number of cluster/plant. Cluster-II for vine length, per cent fruit set, pod length, pod width, pod weight and number of seed /pod, cluster III for number of pods/cluster and pod yield /plant. Selection of parent genotypes from divergent cluster and component having more than one positive trait of interest for hybridization is likely to give better progenies for development of high yielding varieties in Dolichos bean.

Diversity in Phenotypic Traits and Mineral Elements of Okra (Abelmoschus esculentus L. Moench) Genotypes

African indigenous vegetables need to be improved for yield and nutrient enhancement. This can initially be done through germplasm characterization to know the pattern of genetic diversity for germplasm collection, conservation, and plant breeding programme. This research work was carried out to elucidate the diversity present in forty genotypes of okra in Nigeria as regards their qualitative and quantitative traits together with their mineral elements using cluster analysis and principal component analysis so as to help breeders in crop improvement programmes to select appropriate parents to produce new and better varieties. The experiment was carried out at the Teaching and Research Farm of the Department of Crop, Soil and Pest Management, Federal University of Technology, Akure, during the rainy season in 2019. Principal component analysis and cluster analysis were employed to study the diversity present in the okra genotypes. There was great diversity among the forty genotypes of okra studied with respect to qualitative traits. There were highly significant differences P < 0.01 for all the quantitative characters, which indicated the presence of a great amount of diversity in all the characters studied. Single-linkage cluster analysis shows that, at 100% level of similarity, all the genotypes were distinct from one another. Results of the principal component analysis showed that 76.30% of the total variability among the okra genotypes evaluated in this study was accounted for the first five principal components. This study suggests that there is great diversity among the genotypes studied, which could be used by breeders for okra improvement.

Phylogenetic structure of Shiga toxin-producing Escherichia coli O157:H7 from sub-lineage to SNPs.

Sequence similarity of pathogen genomes can infer the relatedness between isolates as the fewer genetic differences identified between pairs of isolates, the less time since divergence from a common ancestor. Clustering based on hierarchical single linkage clustering of pairwise SNP distances has been employed to detect and investigate outbreaks. Here, we evaluated the evidence-base for the interpretation of phylogenetic clusters of Shiga toxin-producing Escherichia coli (STEC) O157:H7. Whole genome sequences of 1193 isolates of STEC O157:H7 submitted to Public Health England between July 2015 and December 2016 were mapped to the Sakai reference strain. Hierarchical single linkage clustering was performed on the pairwise SNP difference between all isolates at descending distance thresholds. Cases with known epidemiological links fell within 5-SNP single linkage clusters. Five-SNP single linkage community clusters where an epidemiological link was not identified were more likely to be temporally and/or geographically related than sporadic cases. Ten-SNP single linkage clusters occurred infrequently and were challenging to investigate as cases were few, and temporally and/or geographically dispersed. A single linkage cluster threshold of 5-SNPs has utility for the detection of outbreaks linked to both persistent and point sources. Deeper phylogenetic analysis revealed that the distinction between domestic UK and imported isolates could be inferred at the sub-lineage level. Cases associated with domestically acquired infection that fall within clusters that are predominantly travel associated are likely to be caused by contaminated imported food.

Variability analysis of some genotypes in Nigeria tea (Camellia sinensis) germplasm

Thirty four tea clones were sourced from Cocoa Research Institute of Nigeria tea germplasm and raised through stem cuttings for 10 months in the nursery. The experiment was laid out in a randomized complete block design (RCBD) with 3 replications in 2016. Agronomic and yield data were collected and subjected to analysis of variance. Single linkage cluster analysis (SLCA), principal component analysis (PCA) and FATCLUS analysis were employed to analyse the data. ANOVA showed considerable significant variation p<0.05 among the 34 tea genotypes. The PCA showed that Plant Height (PH) 0.39, Number of Leaves (NL) 0.38, Number of Branches (NB) 0.37, Harvestable Points (HP) 0.31, Stem Diameter 0.39 and Leaf Breadth 0.30 accounted for most of the variations observed. Axes 1, 2 and 3 of the PCA accounted for 37.23%, 15.48% and 10.75% variability respectively with cumulative value of 63.47%. The genotypes were clustered into 7 groups by FASTCLUS Analysis. The dendrogram showed that the first cluster was observed between NGC29 and NGC 47 at 0.08 level of similarity. At 0.50 level of similarity the dendrogram revealed 5 distinct groups. Therefore, variation exists among the tea germplasm in Nigeria thereby suggests further presenting opportunities for further varietal development.

Development and evaluation of an outbreak surveillance system integrating whole genome sequencing data for non-typhoidal Salmonella in London and South East of England, 2016-17.

An outbreak surveillance system for Salmonella integrating whole genome sequencing (WGS) and epidemiological data was developed in South East and London in 2016-17 to assess local WGS clusters for triage and investigation. Cases genetically linked within a 5 single-nucleotide polymorphism (SNP) single linkage cluster were assessed using a set of locally agreed thresholds based on time, person and place, for reporting to local health protection teams (HPTs). Between September 2016 and September 2017, 230 unique 5-SNP clusters (442 weekly reports) of non-typhoidal Salmonella 5-SNP WGS clusters were identified, of which 208 unique 5-SNP clusters (316 weekly reports) were not reported to the HPTs. In the remaining 22 unique clusters (126 weekly clusters) reported to HPTs, nine were known active outbreak investigations, seven were below locally agreed thresholds and six exceeded local thresholds. A common source or vehicle was identified in four of six clusters that exceeded locally agreed thresholds. This work demonstrates that a threshold-based surveillance system, taking into account time, place and genetic relatedness, is feasible and effective in directing the use of local public health resources for risk assessment and investigation of non-typhoidal Salmonella clusters.

Listeria monocytogenes in Cooked Chicken: Detection of an Outbreak in the United Kingdom (2016 to 2017) and Analysis of L. monocytogenes from Unrelated Monitoring of Foods (2013 to 2017)

In England and Wales, Public Health England applies whole genome sequencing to cultures of Listeria monocytogenes recovered from human cases of listeriosis, foods, and food production environments. Following the routine inspection of a small retailer in February and March 2016, two unopened packs of cooked chicken produced by the same manufacturer were found to be contaminated with L. monocytogenes at levels of 340 and 20 CFU/g. A public recall of this product was issued in March 2016. Early in 2017, a less than five single-nucleotide polymorphism single-linkage cluster was detected between the L. monocytogenes isolates from the two cooked chicken products and cultures from five cases of human listeriosis in England and Scotland with onsets of illness between March 2016 and February 2017. Epidemiological data provided further supportive evidence that this cluster was an outbreak linked to a manufacturer of cooked chicken whose products were supplied to the small retailer that initiated the outbreak investigation. Unrelated to this outbreak, 34 L. monocytogenes isolates recovered from routine food monitoring of 2,007 samples of cooked chicken during 2013 to 2017 were analyzed by whole genome sequencing. Previously undetected fewer than five single-nucleotide polymorphism single-linkage clusters were identified between cultures from cooked chicken and with those from two clusters and two sporadic cases of human listeriosis that were consistent with foodborne transmission. This analysis identified linkage of L. monocytogenes clusters within specific food chains more readily than traditional manual tracing. Linking of data associated with L. monocytogenes cultures from cases of listeriosis with those from unrelated food testing is a unique source of information for communicable disease risk assessment, epidemiological studies, and disease prevention and control. This report provides further evidence that should act as a reminder of the association between cooked chicken consumption and human listeriosis.

Applications of miospore quantitative stratigraphy and cyclostratigraphy in the Neocomian - Cenomanian sediments in the Western Desert, Egypt: A step in the way to biochronostratigraphy

The Lower Cretaceous section in the Western Desert witnesses regular petroleum exploration activities and contains active petroleum systems. The main tool for biostratigraphic classification of these important strata is the palynology based biozonation. The classical biozonation methods that rely on the ranges between only selected zonal palynomorphs markers or bioevents cause many problems in the correlation of the stratigraphic units. These problems slowed the development of a unified scheme and constructions of a time scale. In this study, another approach is introduced for the first time to overcome these problems. This approach depends on analytical stratigraphy that is based on a number of quantitative methods in the framework of the geo-mathematics. These quantitative methods include statistical constrained single linkage cluster analysis, graphic correlation, constrained optimization, ranking and scaling and unitary associations. These methods take into account all of the identified taxa bioevents or their co-existences. Each of these methods produces a biozonation that predict the real distribution of the palynomorphs in time and space in a different approach. In addition, these methods rank and scale the taxa bioevents in a way that can be calibrated to a time scale. The resulted biozonations are comparable through the methods. The study is based on the miospore records of 15 wells that are closely spaced to become the center for future correlations. This is an important step toward the biochronology that add the time dimension to the biostratigraphic analysis. In addition, the present study introduces for the first time the astronomical time calibration in Bassel-1 well based on the principles of cyclostratigraphy including time series analysis and age model tuning. The G-ray log of this well is tuned to 405 kyr eccentricity cycle to produce an age model that anchored on the OAEs. The age model can be developed by additional calibration and tuned to a higher resolution and used in other applications.

Morphological and molecular studies of three species of Boerhavia L. from Ile-Ife, Nigeria

A wide range of plasticity and polymorphism have been documented in the genus Boerhavia. More so, the possible presence of natural hybrids among the species of the genus has made species identification more difficult. This study employed morphological characters, pollen parameters as well as Random Amplified Polymorphic DNA (RAPD) to identify and elucidate the phylogenetic relationship that exists among the three species of Boerhavia distributed in Ile-Ife, Nigeria. Qualitative and quantitative morphological characters were observed and measured respectively. The acetolysis of the pollen grains was carried out according to Erdtman method. Fresh and young leaves of the Boerhavia species studied were collected for genomic DNA extraction using modified Dellarpota procedure. The quality and concentration of DNA was assessed by gel electrophoresis on 2% agarose with known concentrations of undigested lambda DNA. Subsequently, the DNA quantification was done according to standard measurement. The Principal Components Analysis of the morphological traits and the pollen grain studies indicated that the three Boerhavia species studied have a very high level of relationship. However, the Single Linkage Cluster Analysis of the morphological data and the unweighted pair group method with arithmetic mean (UPGMA) cluster analysis of RAPD data revealed that B. erecta is distantly related to B. coccinea and B. diffusa. Despite the fact that the three Boerhavia species studied possess high level of similarity, they can still be distinguished from each other. In conclusion, B. coccinea and B. diffusa are more closely related to each other than B. erecta.
 Key words: RAPD marker, Pollen grains, Phylogenetic relationship, Polymorphism

Assessment of Genetic Divergence in Long Day Onion (Allium cepa L.) through Principal Component and Single Linkage Cluster Analysis

To assess the nature and magnitude of genetic diversity in long day onion germplasm by using the principal component analysis and single linkage cluster analysis an experiment was carried out with 34 onion genotypes. High coefficient of variation with wide range in traits indicated an appreciable variability in germplasm. Genotypes were classified into seven principal components having Eigen value > 1, cumulatively accounted for 83.87% of total variability. Principal Component - I contributed for 24.73% of total variation for followed by principal component-II (15.27%). PC-I had high positive loading for bulb weight (0.401), marketable yield (0.338), total bulb yield (0.401) and PC-II had high positive loading for plant height (0.412), PC-III for high T.S.S. (0.276) PC -IV for A grade bulbs (0.436), PC-V for polar diameter of bulbs (0.514), PC-IV negatively loaded with purple blotch (-0.461) and PC-VII for narrow neck thickness (-0 .515). Plotting PC-I aganist PC-II differenciated CITH-O-13, CITH-O-4, CITH-O-22, CITH-O-19, CITH-O-9, CITH-O-6 and CITH-O2 as most divergent genotype.On the basis of single linkage cluster means cluster-I was most importent for average bulb weight, minimum bolters, high marketble bulb percentage high marketable and total bulb yield whereas cluster -II was important for maximum nuber of leaves/plant and minimum neck thicknes. Highest inter-cluster distance was observed between cluter II and Cluster-I(873.5% ).Most divergent genotypes with high inter cluter distance could be the most appropriate parents for crop impovement in onion.

Assessment of Genetic Divergence in Long Day Onion (Allium cepa L.) through Principal Component and Single Linkage Cluster Analysis

To assess the nature and magnitude of genetic diversity in long day onion germplasm by using the principal component analysis and single linkage cluster analysis an experiment was carried out with 34 onion genotypes. High coefficient of variation with wide range in traits indicated an appreciable variability in germplasm. Genotypes were classified into seven principal components having Eigen value > 1, cumulatively accounted for 83.87% of total variability. Principal Component - I contributed for 24.73% of total variation for followed by principal component-II (15.27%). PC-I had high positive loading for bulb weight (0.401), marketable yield (0.338), total bulb yield (0.401) and PC-II had high positive loading for plant height (0.412), PC-III for high T.S.S. (0.276) PC -IV for A grade bulbs (0.436), PC-V for polar diameter of bulbs (0.514), PC-IV negatively loaded with purple blotch (-0.461) and PC-VII for narrow neck thickness (-0 .515). Plotting PC-I aganist PC-II differenciated CITH-O-13, CITH-O-4, CITH-O-22, CITH-O-19, CITH-O-9, CITH-O-6 and CITH-O2 as most divergent genotype.On the basis of single linkage cluster means cluster-I was most importent for average bulb weight, minimum bolters, high marketble bulb percentage high marketable and total bulb yield whereas cluster -II was important for maximum nuber of leaves/plant and minimum neck thicknes. Highest inter-cluster distance was observed between cluter II and Cluster-I(873.5% ).Most divergent genotypes with high inter cluter distance could be the most appropriate parents for crop impovement in onion.

The orbital clusters among the near-Earth asteroids

ABSTRACT Fifteen orbital clusters (associations) were identified among ${\sim }20\, 000$ near-Earth asteroids (NEAs). All associations were found with a high statistical reliability using a single linkage cluster analysis algorithm and three orbital similarity functions. The identified groups constitute a small fraction (4.74 per cent) of the entire sample. Notwithstanding, they may be hazardous to Earth and its inhabitants. As with meteoroid streams, every year Earth comes very close to the orbits of each association. In two cases (2008TC3 and 2017FU102), the distance between the asteroid’s orbit and Earth’s orbit was shorter than Earth’s radius. Among the members of the identified associations, we found 331 objects larger than the Chelyabinsk asteroid and all of them approach Earth’s orbit at a distance smaller than 0.05 au. Two of the identified groups, (4179) Toutatis and (251430) Itokawa, support the hypothesis regarding the catastrophic origins of the asteroids Toutatis and Itokawa through violent collisions. This study does not focus on the origin of the NEA associations, but rather focuses on tracing the associations. Regardless of their origin, the identified groups pose a serious threat to Earth. Hence, to facilitate their monitoring of we calculated coordinates of the theoretical radiants and the calendar dates of their potential activity.

General Trend of a Negative Li Effective Charge in Ionic Liquid Electrolytes.

We show that strong cation-anion interactions in a wide range of lithium-salt/ionic liquid mixtures result in a negative lithium transference number, using molecular dynamics simulations and rigorous concentrated solution theory. This behavior fundamentally deviates from that obtained using self-diffusion coefficient analysis and explains well recent experimental electrophoretic nuclear magnetic resonance measurements, which account for ion correlations. We extend these findings to several ionic liquid compositions. We investigate the degree of spatial ionic coordination employing single-linkage cluster analysis, unveiling asymmetrical anion-cation clusters. We formulate a way to compute the effective lithium charge and show that lithium-containing clusters carry a negative charge over a remarkably wide range of compositions and concentrations. This finding has significant implications for the overall performance of battery cells based on ionic liquid electrolytes. It also provides a rigorous prediction recipe and design protocol for optimizing transport properties in next-generation highly correlated electrolytes.