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103 results on '"Donkor, E."'

1. Data-driven discovery of statistically relevant information in quantum simulators

Author

Verdel, R., Vitale, V., Panda, R. K., Donkor, E. D., Rodriguez, A., Lannig, S., Deller, Y., Strobel, H., Oberthaler, M. K., and Dalmonte, M.

Subjects
Condensed Matter - Quantum Gases, Condensed Matter - Statistical Mechanics, Physics - Data Analysis, Statistics and Probability, Quantum Physics
Abstract

Quantum simulators offer powerful means to investigate strongly correlated quantum matter. However, interpreting measurement outcomes in such systems poses significant challenges. Here, we present a theoretical framework for information extraction in synthetic quantum matter, illustrated for the case of a quantum quench in a spinor Bose-Einstein condensate experiment. Employing non-parametric unsupervised learning tools that provide different measures of information content, we demonstrate a system-agnostic approach to identify dominant degrees of freedom. This enables us to rank operators according to their relevance, akin to effective field theory. To characterize the corresponding effective description, we then explore the intrinsic dimension of data sets as a measure of the complexity of the dynamics. This reveals a simplification of the data structure, which correlates with the emergence of time-dependent universal behavior in the studied system. Our assumption-free approach can be immediately applied in a variety of experimental platforms., Comment: Published version

Published
2023
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6. Genetic Diversity of Tiger Nuts (Cyperus esculentus L.) Grown in Ghana Based on Morpho-Descriptors and SSR Markers.

Author

Twumasi, P., Asare, P. A., Afutu, E., Amenorpe, G., Addy, S. N. T. T., Prempeh, R., and Donkor, E. F.

Subjects
YELLOW nutsedge, TIGERS, GENETIC variation, GENETIC distance, EUCLIDEAN distance, INFLORESCENCES
Abstract

Purpose: Limited information is available on the diversity of tiger nuts in Ghana for improvement. Therefore, evaluating the genetic diversity via the use of morphological descriptors and molecular markers (SSR) should generate substantial evidence to reveal the variability among and within the crop. Research Method: Forty-two (42) accessions of Cyperus esculentus Lativum were collected from major tiger nut cultivation areas (phytogeographic zones) in Ghana and evaluated using 11 morphodescriptors and 9 SSR markers to assess variability among and within the tiger nut accessions and underlined causes. Findings: Significant differences were observed among the accessions in terms of percentage inflorescence (p≤0.01), distance of the last tiller from the main plant (p≤0.05) and the number of tubers per stand (p≤0.05). Unweighted Pair Group Method with Arithmetic Mean (UPGMA) cluster analysis grouped the accessions into seven clusters including one large heterogenous cluster at 0.94 Euclidean distance, and genetic distance ranged from 0.8 to 1.00. The SSR profiling revealed 141 alleles across 41 of the accessions used for the molecular study with a mean PIC value of 0.78 ± 0.15 and mean observed heterozygosity of 0.12 ± 0.16 coupled with four heterotic UPGMA cluster groupings including one large heterogenous cluster at a similarity coefficient of 0.88. The high variability among the accessions for some of the traits, and the low genetic variability within the accessions in cluster groupings for both morphological and SSR evaluations suggested some level of admixture of genes over years of cultivation. Originality/ Value: The current study has identified some accessions for improvement. Also, it has contributed to knowing some SSR markers that would amplify tiger nuts for future molecular study for breeding enhancement. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Data-driven discovery of relevant information in quantum simulators

Author

Verdel, R., Vitale, V., Panda, R. K., Donkor, E. D., Rodriguez, A., Lannig, S., Deller, Y., Strobel, H., Oberthaler, M. K., and Dalmonte, M.

Subjects
Quantum Physics, Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Physics - Data Analysis, Statistics and Probability, FOS: Physical sciences, Condensed Matter - Quantum Gases, Quantum Physics (quant-ph), Condensed Matter - Statistical Mechanics, Data Analysis, Statistics and Probability (physics.data-an)
Abstract

Quantum simulators offer powerful means to investigate strongly correlated quantum matter. However, interpreting measurement outcomes in such systems poses significant challenges. Here, we present a theoretical framework for information extraction in synthetic quantum matter, illustrated for the case of a quantum quench in a spinor Bose-Einstein condensate experiment. Employing non-parametric unsupervised learning tools that provide different measures of information content, we demonstrate a system-agnostic approach to identify dominant degrees of freedom. This enables us to rank operators according to their relevance, akin to effective field theory. To characterize the corresponding effective description, we then explore the intrinsic dimension of data sets as a measure of the complexity of the dynamics. This reveals a simplification of the data structure, which correlates with the emergence of time-dependent universal behavior in the studied system. Our assumption-free approach can be immediately applied in a variety of experimental platforms., Comment: 5+5 pages, 3+5 figures

Published
2023
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9. International links between Streptococcus pneumoniae vaccine serotype 4 sequence type (ST) 801 in Northern European shipyard outbreaks of invasive pneumococcal disease

Author

Gladstone, R.A., Siira, L., Brynildsrud, O.B., Vestrheim, D.F., Turner, P., Clarke, S.C., Srifuengfung, S., Ford, R., Lehmann, D., Egorova, E., Voropaeva, E., Haraldsson, G., Kristinsson, K.G., McGee, L., Breiman, R.F., Bentley, S.D., Sheppard, C.L., Fry, N.K., Corander, J., Toropainen, M., Steens, A., Akpaka, P.E., Ampofo, K., Antonio, M., Balaji, V., Beall, B.W., Belabbès, H., Benisty, R., Bigogo, G., Brooks, A.W., Carter, P.E., Cornick, J.E., Corso, A., Cristina de Cunto Brandileone, M., Cristine Grassi Almeida, S., Croucher, N.J., Dagan, R., Davydov, A., Diawara, I., Doiphode, S., du Plessis, M., Elmdaghri, N., Köseoglu Eser, Ö., Everett, D.B., Faccone, D., Gagetti, P., Givon-Lavi, N., Hasanuzzaman, M., Hawkins, P.A., Hryniewicz, W., Hulten, K.G., Ip, M., Kapusta, A., Kandasamy, R., Kastrin, T., Keenan, J., Klugman, K.P., Kwambana-Adams, B., Law, P.Y., Lees, J.A., Leung Ho, P., Li, Y., Lo, S.W., Ochoa Woodell, Theresa Jean, Madhi, S.A., Metcalf, B.J., Moïsi, J., Mucavele Fundação Manhiça, H., Ndlangisa, K.M., Nurse-Lucas, M., Nzenze, S.A., Obaro, S.K., Paragi, M., Pollard, A.J., Ravikumar, K.L., Sadowy, E., Saha, S.K., Sampane-Donkor, E., Devi Sekaran, S., Shakoor, S., Shrestha, S., Sigauque, B., Skoczynska, A., Soo ko, K., Tientcheu, P.-E., Titov, L., Urban, Y., Verani, J., van Tonder, A.J., von Gottberg, A., Wolter, N., The Global Pneumococcal Sequencing Consortium, and Consortium, The Global Pneumococcal Sequencing

Subjects
Northern Ireland, Serogroup, Polymorphism, Single Nucleotide, Pneumococcal Infections, Disease Outbreaks, Occupational Exposure, PPV23, Humans, Serotyping, Finland, Phylogeny, Ships, General Veterinary, General Immunology and Microbiology, Norway, Public Health, Environmental and Occupational Health, Outbreak, ST801, PCVs, Infectious Diseases, Streptococcus pneumoniae, Serotype 4, Whole genome sequencing, Molecular epidemiology, Molecular Medicine, Pneumococcal, Genome, Bacterial
Abstract

Background Pneumococcal disease outbreaks of vaccine preventable serotype 4 sequence type (ST)801 in shipyards have been reported in several countries. We aimed to use genomics to establish any international links between them. Methods Sequence data from ST801-related outbreak isolates from Norway (n = 17), Finland (n = 11) and Northern Ireland (n = 2) were combined with invasive pneumococcal disease surveillance from the respective countries, and ST801-related genomes from an international collection (n = 41 of > 40,000), totalling 106 genomes. Raw data were mapped and recombination excluded before phylogenetic dating. Results Outbreak isolates were relatively diverse, with up to 100 SNPs (single nucleotide polymorphisms) and a common ancestor estimated around the year 2000. However, 19 Norwegian and Finnish isolates were nearly indistinguishable (0–2 SNPs) with the common ancestor dated around 2017. Conclusion The total diversity of ST801 within the outbreaks could not be explained by recent transmission alone, suggesting that harsh environmental and associated living conditions reported in the shipyards may facilitate invasion of colonising pneumococci. However, near identical strains in the Norwegian and Finnish outbreaks does suggest that transmission between international shipyards also contributed to those outbreaks. This indicates the need for improved preventative measures in this working population including pneumococcal vaccination.

Published
2022

10. A mosaic tetracycline resistance gene tet(S/M) detected in an MDR pneumococcal CC230 lineage that underwent capsular switching in South Africa

Author

Lo, SW, Gladstone, RA, Van Tonder, AJ, Du Plessis, M, Cornick, JE, Hawkins, PA, Madhi, SA, Nzenze, SA, Kandasamy, R ; https://orcid.org/0000-0002-3111-5586, Ravikumar, KL, Elmdaghri, N, Kwambana-Adams, B, Almeida, SCG, Skoczynska, A, Egorova, E, Titov, L, Saha, SK, Paragi, M, Everett, DB, Antonio, M, Klugman, KP, Li, Y, Metcalf, BJ, Beall, B, McGee, L, Breiman, RF, Bentley, SD, Von Gottberg, A, Brooks, AW, Corso, A, Davydov, A, Maguire, A, Pollard, AJ, Kiran, A, Moiane, B, Sigauque, B, Aanensen, D, Lehmann, D, Faccone, D, Foster-Nyarko, E, Bojang, E, Voropaeva, E, Sampane-Donkor, E, Sadowy, E, Nagaraj, G, Bigogo, G, Mucavele, H, Belabbès, H, Diawara, I, Moïsi, J, Verani, J, Keenan, J, Nair Thulasee Bhai, JN, Ndlangisa, KM, Zerouali, K, De Gouveia, L, Alaerts, M, De Cunto Brandileone, MC, Ip, M, Hasanuzzaman, M, Ali, M, Croucher, N, Wolter, N, Givon-Lavi, N, Eser, ÖK, Ho, PL, Akpaka, PE, Turner, P, Gagetti, P, Tientcheu, PE, Carter, PE, Law, P, Benisty, R, Mostowy, R, Ford, R, Henderson, R, Malaker, R, Dagan, R, Shakoor, S, Doiphode, S, Sekaran, SD, Srifuengfung, S, Obaro, S, Clarke, SC, Kastrin, T, Ochoa, TJ, Hryniewicz, W, Balaji, V, Urban, Y, Lo, SW, Gladstone, RA, Van Tonder, AJ, Du Plessis, M, Cornick, JE, Hawkins, PA, Madhi, SA, Nzenze, SA, Kandasamy, R ; https://orcid.org/0000-0002-3111-5586, Ravikumar, KL, Elmdaghri, N, Kwambana-Adams, B, Almeida, SCG, Skoczynska, A, Egorova, E, Titov, L, Saha, SK, Paragi, M, Everett, DB, Antonio, M, Klugman, KP, Li, Y, Metcalf, BJ, Beall, B, McGee, L, Breiman, RF, Bentley, SD, Von Gottberg, A, Brooks, AW, Corso, A, Davydov, A, Maguire, A, Pollard, AJ, Kiran, A, Moiane, B, Sigauque, B, Aanensen, D, Lehmann, D, Faccone, D, Foster-Nyarko, E, Bojang, E, Voropaeva, E, Sampane-Donkor, E, Sadowy, E, Nagaraj, G, Bigogo, G, Mucavele, H, Belabbès, H, Diawara, I, Moïsi, J, Verani, J, Keenan, J, Nair Thulasee Bhai, JN, Ndlangisa, KM, Zerouali, K, De Gouveia, L, Alaerts, M, De Cunto Brandileone, MC, Ip, M, Hasanuzzaman, M, Ali, M, Croucher, N, Wolter, N, Givon-Lavi, N, Eser, ÖK, Ho, PL, Akpaka, PE, Turner, P, Gagetti, P, Tientcheu, PE, Carter, PE, Law, P, Benisty, R, Mostowy, R, Ford, R, Henderson, R, Malaker, R, Dagan, R, Shakoor, S, Doiphode, S, Sekaran, SD, Srifuengfung, S, Obaro, S, Clarke, SC, Kastrin, T, Ochoa, TJ, Hryniewicz, W, Balaji, V, and Urban, Y

Abstract

Objectives: We reported tet(S/M) in Streptococcus pneumoniae and investigated its temporal spread in relation to nationwide clinical interventions. Methods: We whole-genome sequenced 12 254 pneumococcal isolates from 29 countries on an Illumina HiSeq sequencer. Serotype, multilocus ST and antibiotic resistance were inferred from genomes. An SNP tree was built using Gubbins. Temporal spread was reconstructed using a birth-death model. Results: We identified tet(S/M) in 131 pneumococcal isolates and none carried other known tet genes. Tetracycline susceptibility testing results were available for 121 tet(S/M)-positive isolates and all were resistant. A majority (74%) of tet(S/M)-positive isolates were from South Africa and caused invasive diseases among young children (59% HIV positive, where HIV status was available). All but two tet(S/M)-positive isolates belonged to clonal complex (CC) 230. A global phylogeny of CC230 (n=389) revealed that tet(S/M)-positive isolates formed a sublineage predicted to exhibit resistance to penicillin, co-trimoxazole, erythromycin and tetracycline. The birth-death model detected an unrecognized outbreak of this sublineage in South Africa between 2000 and 2004 with expected secondary infections (effective reproductive number, R) of ∼2.5. R declined to ∼1.0 in 2005 and <1.0 in 2012. The declining epidemic could be related to improved access to ART in 2004 and introduction of pneumococcal conjugate vaccine (PCV) in 2009. Capsular switching from vaccine serotype 14 to non-vaccine serotype 23A was observed within the sublineage. Conclusions: The prevalence of tet(S/M) in pneumococci was low and its dissemination was due to an unrecognized outbreak of CC230 in South Africa. Capsular switching in this MDR sublineage highlighted its potential to continue to cause disease in the post-PCV13 era.

Published
2020

11. Visualizing variation within global pneumococcal sequence clusters (GPSCS) and country population snapshots to contextualize pneumococcal isolates

Author

Gladstone, RA, Lo, SW, Goater, R, Yeats, C, Taylor, B, Hadfield, J, Lees, JA, Croucher, NJ, van Tonder, AJ, Bentley, LJ, Quah, FX, Blaschke, AJ, Pershing, NL, Byington, CL, Balaji, V, Hryniewicz, W, Sigauque, B, Ravikumar, KL, Almeida, SCG, Ochoa, TJ, Ho, PL, Plessis, MD, Ndlangisa, KM, Cornick, JE, Kwambana-Adams, B, Benisty, R, Nzenze, SA, Madhi, SA, Hawkins, PA, Pollard, AJ, Everett, DB, Antonio, M, Dagan, R, Klugman, KP, von Gottberg, A, Metcalf, BJ, Li, Y, Beall, BW, McGee, L, Breiman, RF, Aanensen, DM, Bentley, SD, Akpaka, PE, Ampofo, K, Belabbès, H, Bigogo, G, Brooks, AW, Carter, PE, Clarke, SC, Corso, A, de Cunto Brandileone, MC, Davydov, A, Diawara, I, Doiphode, S, Egorova, E, Elmdaghri, N, Eser, ÖK, Faccone, D, Ford, R, Gagetti, P, Givon-Lavi, N, Hasanuzzaman, M, Hulten, KG, Ip, M, Kapusta, A, Kandasamy, R ; https://orcid.org/0000-0002-3111-5586, Kastrin, T, Keenan, J, Law, PY, Lehmann, D, Moïsi, J, Mucavele, H, Nurse-Lucas, M, Obaro, SK, Paragi, M, Sadowy, E, Saha, SK, Sampane-Donkor, E, Sekaran, SD, Shakoor, S, Shrestha, S, Skoczynska, A, Ko, S, Srifuengfung, S, Tientcheu, PE, Titov, L, Turner, P, Urban, Y, Verani, J, Voropaeva, E, Wolter, N, Gladstone, RA, Lo, SW, Goater, R, Yeats, C, Taylor, B, Hadfield, J, Lees, JA, Croucher, NJ, van Tonder, AJ, Bentley, LJ, Quah, FX, Blaschke, AJ, Pershing, NL, Byington, CL, Balaji, V, Hryniewicz, W, Sigauque, B, Ravikumar, KL, Almeida, SCG, Ochoa, TJ, Ho, PL, Plessis, MD, Ndlangisa, KM, Cornick, JE, Kwambana-Adams, B, Benisty, R, Nzenze, SA, Madhi, SA, Hawkins, PA, Pollard, AJ, Everett, DB, Antonio, M, Dagan, R, Klugman, KP, von Gottberg, A, Metcalf, BJ, Li, Y, Beall, BW, McGee, L, Breiman, RF, Aanensen, DM, Bentley, SD, Akpaka, PE, Ampofo, K, Belabbès, H, Bigogo, G, Brooks, AW, Carter, PE, Clarke, SC, Corso, A, de Cunto Brandileone, MC, Davydov, A, Diawara, I, Doiphode, S, Egorova, E, Elmdaghri, N, Eser, ÖK, Faccone, D, Ford, R, Gagetti, P, Givon-Lavi, N, Hasanuzzaman, M, Hulten, KG, Ip, M, Kapusta, A, Kandasamy, R ; https://orcid.org/0000-0002-3111-5586, Kastrin, T, Keenan, J, Law, PY, Lehmann, D, Moïsi, J, Mucavele, H, Nurse-Lucas, M, Obaro, SK, Paragi, M, Sadowy, E, Saha, SK, Sampane-Donkor, E, Sekaran, SD, Shakoor, S, Shrestha, S, Skoczynska, A, Ko, S, Srifuengfung, S, Tientcheu, PE, Titov, L, Turner, P, Urban, Y, Verani, J, Voropaeva, E, and Wolter, N

Abstract

Knowledge of pneumococcal lineages, their geographic distribution and antibiotic resistance patterns, can give insights into global pneumococcal disease. We provide interactive bioinformatic outputs to explore such topics, aiming to increase dissemi-nation of genomic insights to the wider community, without the need for specialist training. We prepared 12 country-specific phylogenetic snapshots, and international phylogenetic snapshots of 73 common Global Pneumococcal Sequence Clusters (GPSCs) previously defined using PopPUNK, and present them in Microreact. Gene presence and absence defined using Roary, and recombination profiles derived from Gubbins are presented in Phandango for each GPSC. Temporal phylogenetic signal was assessed for each GPSC using BactDating. We provide examples of how such resources can be used. In our example use of a country-specific phylogenetic snapshot we determined that serotype 14 was observed in nine unrelated genetic backgrounds in South Africa. The international phylogenetic snapshot of GPSC9, in which most serotype 14 isolates from South Africa were observed, highlights that there were three independent sub-clusters represented by South African serotype 14 isolates. We estimated from the GPSC9-dated tree that the sub-clusters were each established in South Africa during the 1980s. We show how recombination plots allowed the identification of a 20 kb recombination spanning the capsular polysaccharide locus within GPSC97. This was consistent with a switch from serotype 6A to 19A estimated to have occured in the 1990s from the GPSC97-dated tree. Plots of gene presence/absence of resistance genes (tet, erm, cat) across the GPSC23 phylogeny were consistent with acquisition of a composite transposon. We estimated from the GPSC23-dated tree that the acquisition occurred between 1953 and 1975. Finally, we demonstrate the assignment of GPSC31 to 17 externally generated pneumococcal serotype 1 assemblies from Utah via Pathogenwatch. Most of

Published
2020

12. Pneumococcal lineages associated with serotype replacement and antibiotic resistance in childhood invasive pneumococcal disease in the post-PCV13 era: an international whole-genome sequencing study

Author

Lo, SW, Gladstone, RA, van Tonder, AJ, Lees, JA, du Plessis, M, Benisty, R, Givon-Lavi, N, Hawkins, PA, Cornick, JE, Kwambana-Adams, B, Law, PY, Ho, PL, Antonio, M, Everett, DB, Dagan, R, von Gottberg, A, Klugman, KP, McGee, L, Breiman, RF, Bentley, SD, Brooks, AW, Corso, A, Davydov, A, Maguire, A, Pollard, A, Kiran, A, Skoczynska, A, Moiane, B, Beall, B, Sigauque, B, Aanensen, D, Lehmann, D, Faccone, D, Foster-Nyarko, E, Bojang, E, Egorova, E, Voropaeva, E, Sampane-Donkor, E, Sadowy, E, Bigogo, G, Mucavele, H, Belabbès, H, Diawara, I, Moïsi, J, Verani, J, Keenan, J, Nair Thulasee Bhai, JN, Ndlangisa, KM, Zerouali, K, Ravikumar, KL, Titov, L, De Gouveia, L, Alaerts, M, Ip, M, de Cunto Brandileone, MC, Hasanuzzaman, M, Paragi, M, Nurse-Lucas, M, Ali, M, Elmdaghri, N, Croucher, N, Wolter, N, Porat, N, Köseoglu Eser, Ö, Akpaka, PE, Turner, P, Gagetti, P, Tientcheu, PE, Carter, PE, Mostowy, R, Kandasamy, R ; https://orcid.org/0000-0002-3111-5586, Ford, R, Henderson, R, Malaker, R, Shakoor, S, Grassi Almeida, SC, Saha, SK, Doiphode, S, Madhi, SA, Devi Sekaran, S, Srifuengfung, S, Obaro, S, Clarke, SC, Nzenze, SA, Kastrin, T, Ochoa, TJ, Balaji, V, Hryniewicz, W, Urban, Y, Lo, SW, Gladstone, RA, van Tonder, AJ, Lees, JA, du Plessis, M, Benisty, R, Givon-Lavi, N, Hawkins, PA, Cornick, JE, Kwambana-Adams, B, Law, PY, Ho, PL, Antonio, M, Everett, DB, Dagan, R, von Gottberg, A, Klugman, KP, McGee, L, Breiman, RF, Bentley, SD, Brooks, AW, Corso, A, Davydov, A, Maguire, A, Pollard, A, Kiran, A, Skoczynska, A, Moiane, B, Beall, B, Sigauque, B, Aanensen, D, Lehmann, D, Faccone, D, Foster-Nyarko, E, Bojang, E, Egorova, E, Voropaeva, E, Sampane-Donkor, E, Sadowy, E, Bigogo, G, Mucavele, H, Belabbès, H, Diawara, I, Moïsi, J, Verani, J, Keenan, J, Nair Thulasee Bhai, JN, Ndlangisa, KM, Zerouali, K, Ravikumar, KL, Titov, L, De Gouveia, L, Alaerts, M, Ip, M, de Cunto Brandileone, MC, Hasanuzzaman, M, Paragi, M, Nurse-Lucas, M, Ali, M, Elmdaghri, N, Croucher, N, Wolter, N, Porat, N, Köseoglu Eser, Ö, Akpaka, PE, Turner, P, Gagetti, P, Tientcheu, PE, Carter, PE, Mostowy, R, Kandasamy, R ; https://orcid.org/0000-0002-3111-5586, Ford, R, Henderson, R, Malaker, R, Shakoor, S, Grassi Almeida, SC, Saha, SK, Doiphode, S, Madhi, SA, Devi Sekaran, S, Srifuengfung, S, Obaro, S, Clarke, SC, Nzenze, SA, Kastrin, T, Ochoa, TJ, Balaji, V, Hryniewicz, W, and Urban, Y

Abstract

Background: Invasive pneumococcal disease remains an important health priority owing to increasing disease incidence caused by pneumococci expressing non-vaccine serotypes. We previously defined 621 Global Pneumococcal Sequence Clusters (GPSCs) by analysing 20 027 pneumococcal isolates collected worldwide and from previously published genomic data. In this study, we aimed to investigate the pneumococcal lineages behind the predominant serotypes, the mechanism of serotype replacement in disease, as well as the major pneumococcal lineages contributing to invasive pneumococcal disease in the post-vaccine era and their antibiotic resistant traits. Methods: We whole-genome sequenced 3233 invasive pneumococcal disease isolates from laboratory-based surveillance programmes in Hong Kong (n=78), Israel (n=701), Malawi (n=226), South Africa (n=1351), The Gambia (n=203), and the USA (n=674). The genomes represented pneumococci from before and after pneumococcal conjugate vaccine (PCV) introductions and were from children younger than 3 years. We identified predominant serotypes by prevalence and their major contributing lineages in each country, and assessed any serotype replacement by comparing the incidence rate between the pre-PCV and PCV periods for Israel, South Africa, and the USA. We defined the status of a lineage as vaccine-type GPSC (≥50% 13-valent PCV [PCV13] serotypes) or non-vaccine-type GPSC (>50% non-PCV13 serotypes) on the basis of its initial serotype composition detected in the earliest vaccine period to measure their individual contribution toward serotype replacement in each country. Major pneumococcal lineages in the PCV period were identified by pooled incidence rate using a random effects model. Findings: The five most prevalent serotypes in the PCV13 period varied between countries, with only serotypes 5, 12F, 15B/C, 19A, 33F, and 35B/D common to two or more countries. The five most prevalent serotypes in the PCV13 period varied between countries, with

Published
2019

13. Welfare estimates of food safety and quality policy changes in Southern Ghana

Author

Owusu-Sekyere, E., Owusu, V., Donkor, E., and Jordaan, H.

Subjects
Food Consumption/Nutrition/Food Safety
Abstract

The present paper has examined the welfare implications of safety and quality policy changes among beef consumers in Southern Ghana. The empirical results revealed profound heterogeneity in preferences for food safety and quality attributes at individual and segment levels. Four distinct consumer segments were revealed using a latent class model. We show that besides traditional socioeconomic factors; trust, competence and confidence in actors along food safety chain significantly impact on preferences for different food safety and quality policy attributes. Compensating surplus estimates reveal that welfare improvement arising from food safety and quality policy changes varies from one class to another. The findings show evidence of imperative segmental equity issues in food safety and quality policies. The welfare estimates indicate that evaluating willingness to pay values alone is not enough. The paper suggests that future research and policy decisions on food safety and quality changes take into account the segment of consumers whose welfare can potentially be improved or reduced due to the policy changes. Insights from this study are expected to assist policymakers in developing countries, especially in Africa to understand the welfare implications and effective food safety and quality measures Acknowledgement

Published
2018
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14. EVALUATION OF TIGERNUT ACCESSIONS IN GHANA FOR PROXIMATE AND MINERAL COMPOSITION.

Author

DONKOR, E. F., NYADANU, D., and DAPAAH, H. K.

Subjects
*YELLOW nutsedge, *MINERALS, *GROWING season, *CARBOHYDRATES
Abstract

Tigernut (Cyperus esculentus L.) is a nutritious, yet underutilised crop in Ghana. The objective of this study was to characterise Ghanaian tigernut accessions for proximate and mineral composition, as a guide for breeders for varietal development. Field and laboratory studies were conducted on 24 tigernut accessions from major growing areas of Ghana. The accessions were cultivated during the minor the growing season (September - November), at the Multipurpose Nursery of the University of Education, Winneba, Asante Mampong in Ghana. The nuts were analysed for proximate (carbohydrate, energy, moisture, ether extract, crude fiber, crude protein and ash) and mineral (potassium, phosphorus and calcium) composition. There were significant (P<0.05) differences among accessions for all traits studied. Accessions were clustered in a dendrogram by colour and geographical origin and PC1 and PC2 explained more than 80% of the total variations among the accessions, with carbohydrate and energy being the major contributors to the total variation. Accessions DY, BKB, KAB, TPY, CCY, WY2 and WY1, which recorded high levels of proximate and mineral compositions, may be considered for breeding programmes to provide high nutrient varieties of tigernut in Ghana. [ABSTRACT FROM AUTHOR]

Published
2021
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16. Assessing the determinants of adoption of improved cassava varieties among farmers in the Ashanti Region of Ghana

Author

Donkor, E and Owusu, V

Abstract

The study examined the adoption of improved cassava varieties among 350 cassava farmers in the Sekyere South District of Ashanti Region of Ghana. The improved cassava varieties introduced into the district were ‘Bankye Hemaa’, ‘Bankye Esam’ and ‘Bankye Afisiafi’. Among the respondents, 15 per cent have adopted at least one of the improved cassava varieties and 85 per cent were non adopters. The determinants of adoption and number of improved cassava varieties adopted by the farmers were analysed with the Probit and Tobit model. The results of the Probit model showed that extension services, access to credit, education, marital status, farmer based organization, and household size have significant positive effect on the probability of farmers to adopt improved cassava varieties. The Tobit estimates indicated that farmer based organization, household size, farm size, and extension contact positively influence the number of improved cassava varieties that farmers adopt. Age had negative influence on number of improved cassava varieties adopted. The study showed that in order to enhance adoption of improved cassava varieties, extension services should be intensified, farmers should form or join groups; farmers should also register with the credit union in the district to have access to credit. Policy makers and crop breeders should come out with varieties that best suit farmers’ objectives.

Published
2015

17. The perception and preference of consumers for local poultry meat in the Kumasi metropolis of Ghana

Author

Atuahene, C C, Atuahene, A J, Adjei, M B, and Donkor, E

Abstract

The study examined the preference for and perception of consumers concerning the locally produced poultry meat in the Kumasi metropolis in the Ashanti Region of Ghana. Fifty consumers were randomly selected. The results demonstrated that most consumers preferred the local poultry meat to the imported meat. The logit estimates indicated that factors such as age, gender, cold store, cut parts, and healthiness significantly influence consumers’ preference for the locally produced poultry meat. Age, gender and healthiness positively influence consumer’s preference, while cold store and cut parts negatively associated with consumer preference for local poultry meat. On the perception, 68 per cent of the consumers strongly agreed that local poultry meat is tough, while 58 per cent alleged that imported poultry meat is rather tough. In terms of affordability, 46 per cent of the consumers disagreed that local poultry meat is affordable, while 52 per cent strongly objected to the idea that imported poultry meat is relatively cheaper. In terms of availability, 54 per cent of the consumers admitted that local poultry meat is not readily available, while 58 per cent indicated that imported poultry meat is readily available and can be obtained at anytime. Sixty per cent of the respondents were of the opinion that local poultry meat taste better, while 46 per cent of the respondents indicated that imported poultry meat do not taste better. This was probably due to long period of refrigeration, which reduced its freshness and taste and made it less healthy for consumption. It is suggested that the government should subsidize the cost of inputs for the local poultry industry, since the results indicated that high cost was the major factor that influenced consumers’ purchasing decision.

Published
2014

19. Coping Strategies of Women Seeking Infertility Treatment in Southern Ghana

Author

Donkor, E. S. and Jane Sandall

Subjects
Coping strategies, Infertility treatment, Southern Ghana
Abstract

Infertility is a health problem faced by an estimated 15% of women of childbearing age in Ghana. This study explores the coping strategies adopted by 615 women seeking infertility treatment in southern Ghana. Both closed and open-ended questions were used through a survey conducted using face-to-face interviews in three languages at three health sites – a hospital, a health centre and a private clinic. The findings suggest that the majority of the women preferred to keep issues of their fertility problems to themselves. The reason could be due to the associated stigma of infertility. Further, the majority of the women coped through drawing on their Christian faith. Others also coped through the support they received from their husbands, their occupation by way of achieving economic independence, and some avoided situations that reminded them of their infertility problem. The findings should have implications for health personnel as some strategies infertile women use may do more harm than good (Afr J Reprod Health 2009; 13[4]:81-93).

Published
2010

20. Dual compressible hybrid quantum secret sharing schemes based on extended unitary operations

Author

Frey, M R, Myers, J M, Donkor, E, Pirich, A R, Brandt, H E, Lomonaco Jr, S J, Lai, Hong, Orgun, Mehmet, Xue, Liyin, Xiao, Jinghua, Pieprzyk, Josef, Frey, M R, Myers, J M, Donkor, E, Pirich, A R, Brandt, H E, Lomonaco Jr, S J, Lai, Hong, Orgun, Mehmet, Xue, Liyin, Xiao, Jinghua, and Pieprzyk, Josef

Abstract

A crucial issue with hybrid quantum secret sharing schemes is the amount of data that is allocated to the participants. The smaller the amount of allocated data, the better the performance of a scheme. Moreover, quantum data is very hard and expensive to deal with, therefore, it is desirable to use as little quantum data as possible. To achieve this goal, we first construct extended unitary operations by the tensor product of n, n ≥ 2, basic unitary operations, and then by using those extended operations, we design two quantum secret sharing schemes. The resulting dual compressible hybrid quantum secret sharing schemes, in which classical data play a complementary role to quantum data, range from threshold to access structure. Compared with the existing hybrid quantum secret sharing schemes, our proposed schemes not only reduce the number of quantum participants, but also the number of particles and the size of classical shares. To be exact, the number of particles that are used to carry quantum data is reduced to 1 while the size of classical secret shares also is also reduced to l−2 m−1 based on ((m+1, n′)) threshold and to l−2 r2 (where r2 is the number of maximal unqualified sets) based on adversary structure. Consequently, our proposed schemes can greatly reduce the cost and difficulty of generating and storing EPR pairs and lower the risk of transmitting encoded particles.

Published
2014

22. Reply to 'Comments on 'An Analytical Two-dimensional Perturbation Method To Model Submicron GaAs MESFET's'.'

Author

Donkor, E. and Jain, F.C.

Subjects
Perturbation (Quantum dynamics) -- Research, Metal oxide semiconductor field effect transistors -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

This paper replies to the suggestions, corrections and comments of Kukreja and Gupta, reported in this issue, on our paper. Their main observation concerns a) constants A(sub n), B(sub n) and C(sub n); in that they obtained different expressions from what we reported, b) the dimensionality and range of applicability of the current-voltage relation, c) details about parameters m(sub 0), and m(sub 1).

Published
1993

27. All Fiber-Based Optical Transmitters and Switching Technologies

Author

CONNECTICUT UNIV STORRS, Cheo, P. K., Donkor, E., CONNECTICUT UNIV STORRS, Cheo, P. K., and Donkor, E.

Abstract

A coupled-cavity mode-locked fiber laser using three Bragg grating in tandem has been demonstrated. The matching of cavity lengths of the two coupled cavities is not critical and the difference in length can be as large as 2 mm still achieving mode-looking. The pulse width of these mode-locked lasers is, longer than the transform-limited value Er-doped fiber lasers are very unstable an usually exhibit self-pulsing behavior. Using a high-gain Er-doped fiber, the instability caused by resonant pump perturbation can be suppressed. One method to suppress the self-pulsing problem is to increase the emission to absorption ratio. Another method is to introduce Ytterbium ions (Yb) into Er-doped fiber. Samples of non-linear CdSSe-doped fibers have been fabricated for single mode operation in the wavelength region between 980nm-1550nm. Linear absorption coefficiently was found to be 0.14 dB/cm at 1550nm. The nonresonant non-linear refractive index was found to be 1.8x10(exp-17)m2/W, 400 times greater than silica fiber.

Published
1997

29. PSYCHOSOCIAL AND PHYSICAL EXPERIENCES OF HAEMODIALYSIS PATIENTS IN GHANA.

Author

Achempim-Ansong, G. and Donkor, E. S.

Subjects
TREATMENT of chronic kidney failure, ACADEMIC medical centers, ANGER, ANXIETY, CONTENT analysis, COUNSELING, MENTAL depression, FEAR, HEALTH services accessibility, HEMODIALYSIS, INTERVIEWING, RESEARCH methodology, RESEARCH, HUMAN sexuality, SLEEP, SOCIAL isolation, QUALITATIVE research, HEMODIALYSIS patients, JUDGMENT sampling, SOCIOECONOMIC factors, MEDICAL coding, ECONOMICS, PSYCHOLOGY
Abstract

The chronicity of end-stage renal disease and the uncertainties surrounding the course of the disease and its treatment necessitate ongoing psychosocial assessment of these patients. This study explored the psychosocial and physical experiences of haemodialysis patients. A qualitative study was conducted in one medical unit of a teaching hospital in Accra, Ghana. A sample of 10 female and male end-stage renal disease patients, undergoing haemodialysis, were recruited. Interviews were audio taped. Data were transcribed verbatim and were analysed through content analysis, coding and categorisation. From the experiences narrated by the participants, four main themes emerged, which were divided into sub-themes. These included: psychological experiences (anxiety, depression, anger, worrying, and fear of death); social experiences (intentional isolation, inability to attend social functions, and effect of dialysis on marriage); economic encounters (difficulty in financing the treatment, loss of income, lowered productivity); and physical experiences (problems with sleeping, with fluid and diet restrictions, and with accessing the treatment site). Based on these findings, it is recommended that counselling ceotres should be attached to dialysis units in order to counsel patients and their families before haemodialysis commences. Future studies should capture how haemodialysis patients cope with their psychosocial experiences. [ABSTRACT FROM AUTHOR]

Published
2012

30. KNOWLEDGE, PRACTICES AND CHALLENGES OF INTERMITTENT MALARIA PREVENTIVE (IPT) TREATMENT DURING PREGNANCY IN GHANA.

Author

Donkor, E. S. and Asiedua, E.

Subjects
MALARIA prevention, ANTIMALARIALS, SULFANILAMIDES, RESEARCH methodology, QUANTITATIVE research, CROSS-sectional method, MALARIA in pregnancy, HEALTH literacy, PREGNANCY, THERAPEUTICS
Abstract

Malaria contributes significantly to maternal morbidity and mortality rates in Ghana. The aim of the study was to investigate the knowledge, practices and challenges encountered in the implementation of sulphadoxine-pyrimethamine (SP) as a measure to prevent malaria occurrences among pregnant women. A quantitative, descriptive, cross-sectional study was conducted. Convenience and purposive sampling techniques were utilised to select 88 women attending antenatal/postnatal clinics and 22 midwives working in these clinics in New Juabeng district in the Eastern Region of Ghana. Questionnaires were used to collect data and analysis was performed using the SPSS program. The findings indicated that the majority of women and midwives knew how malaria is acquired. Most women (92%) knew about SP. The majority learnt about it at the antenatal clinic and some through radio and television programmes. While most women took SP under directly observed therapy, a few were allowed to take their drugs home. Midwives identified challenges such as women's failure to complete the SP regimen; some women receiving the first dose during advanced stages of their pregnancies whilst others received the first dose and never returned for subsequent doses. The findings indicate that nurses' and midwives' education on malaria prevention during pregnancy should be enhanced. [ABSTRACT FROM AUTHOR]

Published
2011

31. Experimental multiuser quantum key distribution network using a wavelength-addressed bus architecture.

Author

Kumavor, P.D., Beal, A.C., Donkor, E., and Wang, B.C.

Abstract

A six-user quantum key distribution network implemented on a bus topology is experimentally demonstrated. The network employs the BB84 protocol to transmit cryptographic keys encoded unto the phase states of highly attenuated laser light to distances of up to 31 km in a standard telecommunication-grade fiber. Each user on the network is assigned a unique wavelength for communication with the network server at a time. The measured quantum bit error rate and sifted key rate compare favorably with theoretical results [ABSTRACT FROM PUBLISHER]

Published
2006
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32. All-optical Lyot-filter-assisted flip-flop operation using a semiconductor optical amplifier.

Author

Kumavor, P.D., Donkor, E., and Wang, B.C.

Abstract

All-optical flip-flop operation using external optical control is demonstrated in a single semiconductor optical amplifier (SOA)-based fiber ring laser with an intracavity Lyot filter. Its operation is based on the principle of cross-gain saturation in the SOA. A unique feature of this flip-flop is its ability to be set and reset at multiple wavelength pairs of an auxiliary continuous wave control light that is injected into the fiber ring cavity; this, together with the wide wavelength tunability of the Lyot filter makes the flip-flop potentially useful in wavelength-division multiplexing applications. Bistable output at 1571 nm with a contrast ratio of 20 dB between the two output power states of the flip-flop using -3 dBm power of the external optical control is demonstrated [ABSTRACT FROM PUBLISHER]

Published
2006
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34. Comparison of four multi-user quantum key distribution schemes over passive optical networks.

Author

Kumavor, P.D., Beal, A.C., Yelin, S., Donkor, E., and Wang, B.C.

Abstract

The performance of four passive optical network topologies in implementing multi-user quantum key distribution is compared. The networks considered are the passive-star network, the optical-ring network based on the Sagnac interferometer, the wavelength-routed network, and the wavelength-addressed bus network. An analysis of the quantum bit-error rate and sifted key rate for each of these topologies is used to determine their suitability for providing service to networks of various sizes. [ABSTRACT FROM PUBLISHER]

Published
2005
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37. Demonstration of a Self-Synchronized Polyphase Sampling and Demultiplexing Scheme for Radio-Frequency Analog Signals.

Author

Villa, C., Kumavor, P., and Donkor, E.

Abstract

A novel self-synchronizing optoelectronics polyphase scheme for sampling and demultiplexing radio-frequency (RF) signals is demonstrated. One unique feature of this approach is that the optically sampled RF signal always remains in the electrical domain and thus eliminates the need for electrical-to-optical and back to electrical conversions. Furthermore, the simplicity and ease of construction of the scheme readily allows it to be scaled to obtain high sampling rates. As a proof of concept, a 100-MHz RF electrical signal sampled at the rate of 1.28 GS/s and then demultiplexed into four 320-MHz signals was experimentally demonstrated. [ABSTRACT FROM PUBLISHER]

Published
2008
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