18 results on '"University of Cape Verde"'
Search Results
2. Diversity and seasonal dynamics of airborne archaea
- Author
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Fröhlich-Nowoisky, J, Ruzene Nespoli, C., Pickersgrill, D.A., Galand, P.E., Müller-Germann, I., Nunes, T., Gomes Cardoso, J., Almeida, S.M., Pio, C., Andreae, M. O., Conrad, R., Pöschl, U., Després, V. R., Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), Laboratoire d'Ecogéochimie des environnements benthiques (LECOB), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Universidade de Aveiro, University of Cape Verde, Universidade de Lisboa = University of Lisbon (ULISBOA), Max Planck Institute for Terrestrial Microbiology, Johannes Gutenberg - Universität Mainz (JGU), and Universidade de Lisboa (ULISBOA)
- Subjects
lcsh:Geology ,lcsh:QH501-531 ,lcsh:QH540-549.5 ,lcsh:QE1-996.5 ,[SDE]Environmental Sciences ,lcsh:Life ,lcsh:Ecology - Abstract
Archaea are widespread and abundant in many terrestrial and aquatic environments, and are thus outside extreme environments, accounting for up to ~10% of the prokaryotes. Compared to bacteria and other microorganisms, however, very little is known about the abundance, diversity, and dispersal of archaea in the atmosphere. By means of DNA analysis and Sanger sequencing targeting the 16S rRNA (435 sequences) and amoA genes in samples of air particulate matter collected over 1 year at a continental sampling site in Germany, we obtained first insights into the seasonal dynamics of airborne archaea. The detected archaea were identified as Thaumarchaeota or Euryarchaeota, with soil Thaumarchaeota (group I.1b) being present in all samples. The normalized species richness of Thaumarchaeota correlated positively with relative humidity and negatively with temperature. This together with an increase in bare agricultural soil surfaces may explain the diversity peaks observed in fall and winter. The detected Euryarchaeota were mainly predicted methanogens with a low relative frequency of occurrence. A slight increase in their frequency during spring may be linked to fertilization processes in the surrounding agricultural fields. Comparison with samples from the Cape Verde islands (72 sequences) and from other coastal and continental sites indicates that the proportions of Euryarchaeota are enhanced in coastal air, which is consistent with their suggested abundance in marine surface waters. We conclude that air transport may play an important role in the dispersal of archaea, including assumed ammonia-oxidizing Thaumarchaeota and methanogens.
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- 2014
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3. Molecular characterization of Cryptosporidium spp. in symptomatic children from Cape Verde.
- Author
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Colito DA, Linaza AXP, García-Livia K, Baz-González E, Martin-Carrillo N, Lima HSDC, Dorta-Guerra R, and Foronda P
- Abstract
Cryptosporidiosis has been identified as one of the leading causes of diarrhea and diarrhea-associated deaths in young children in sub-Saharan Africa. In Cape Verde, available data on human infections caused by Cryptosporidium spp. are limited. The aim of the present study was to analyze the molecular epidemiology of Cryptosporidium spp. in Cape Verde. Stool samples were obtained from patients on the Santiago and Sal islands (Cape Verde), 10/105 (9.5% CI: 4.7; 16.8) from the Santiago Island and 4/85 (4.7% CI: 1.3; 11.6) from the Sal Island presented Cryptosporidium sp., and were analyzed by nested-PCR of the SSU rRNA gene and nested-PCR of the 60 kDa glycoprotein gene for subtyping. The analyses were performed by nested-PCR of the SSU rRNA gene 18Sribosomal RNA gene, and nested-PCR of the 60 kDa glycoprotein gene for subtyping. Two species, Cryptosporidium hominis and Cryptosporidium felis, were identified. In Santiago Island, only C. hominis was detected, while both species were found in Sal Island. The C. hominis IfA14G1R5 subtype was the only identified in children from Santiago and Sal. Although the consumption of non-bottled water is a risk factor for infection by Cryptosporidium spp. on Santiago Island, none of the factors analysed (age, gender, clinical symptoms, source of drinking water, presence of animals at home, attending kindergarten or school, and having a bathroom at home) were significantly related to the presence of Cryptosporidium spp. in Sal Island. Cryptosporidium hominis is the most commonly identified species associated with cryptosporidiosis in the studied population, indicating a predominance of anthroponotic transmission. This study provides the first data on C. hominis subtyping in Cape Verde and the first report of C. felis in humans from this region, demonstrating the possibility of zoonotic transmission. The obtained results highlight the need for further molecular and epidemiological studies of Cryptosporidium spp. infections in human and animals from Cape Verde, in order to investigate the transmission dynamics of cryptosporidiosis and develop effective control strategies to prevent the spread of the disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)
- Published
- 2024
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4. Sickle Cell Anemia Screening in Newborns and Analysis of Haplotypes in Patients from Santiago Island, Cape Verde.
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Freire A, Charola-Ramos L, González-Guerra E, Gonçalves J, Rocha V, Afreixo V, Martínez-Carretero E, and Raya JM
- Abstract
Sickle cell anemia (SCA) results from a mutation in the β -globin gene, leading to the production of mutant hemoglobin, known as hemoglobin S (HbS). Despite being a genetic disorder, the phenotype of SCA can be influenced by the level of fetal hemoglobin (HbF), which is associated with beta S-globin haplotypes. In this study, we conducted newborn screening (NBS) using samples collected from umbilical cord blood in two hospitals on Santiago Island, Cape Verde. In newborns, HbS was detected using high-performance liquid chromatography (HPLC) on dried blood spot, with confirmation through polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). In addition, we assessed the hematological and clinical characteristics of a second population group consisting of patients diagnosed with SCA. Haplotype determination was performed on both newborns with HbS and patients with SCA. Beta S-globin haplotypes were determined using PCR-RFLP. Hematological values were analyzed using standard methods. Out of 346 newborns, 21 (6%) were carriers of the sickle cell trait (HbAS) while none were identified as homozygous for sickle cell disease (HbSS). Among both groups of individuals, four haplotypes were identified: Senegal, Arabi-Indian, Bantu, and Benin. The Senegal haplotype was the most prevalent, possibly reflecting the ethnic origin of the mutations observed. Hematological values did not differ significantly among haplotypes. However, higher levels of HbF were associated with better hematological values. These findings suggest a positive impact of elevated HbF levels on reducing the severity of SCA. Finally, we demonstrated how the combination of technics, HPLC and molecular analysis, provided a consistent and reproducible results that can be used for NBS for SCA., Competing Interests: The authors declare that there are no conflicts of interest., (Copyright © 2024 Ariana Freire et al.)
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- 2024
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5. Influence of hot-smoking on the stability of fresh and frozen-thawed deep-skinned Atlantic mackerel fillets during cold storage.
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Fernandes CM, Sveinsdóttir HI, Tómasson T, Arason S, and Gudjónsdóttir M
- Abstract
Atlantic mackerel ( Scomber scombrus ) caught during the summer months in Icelandic waters after intensive feeding is rich in lipids and, thus, sensitive to lipid degradation. Recent studies have led to improved cooling and handling on board, ensuring high-quality raw material. However, studies on the development of high-quality products for human consumption are lacking. The study aimed to investigate the effects of hot-smoking on the physicochemical, microbial, and sensory quality of deep-skinned Atlantic mackerel fillets during chilled storage (1 ± 0.6°C). In addition, the quality of smoked mackerel from frozen-thawed fillets (9 months at -25 ± 1.8°C) was compared to that of fresh-smoked fillets to evaluate the possibility of the industry being able to provide smoked fillets throughout the year, despite the short fishing season. Brining and hot-smoking reduced total viable counts and inactivated Listeria monocytogenes . Hot-smoking positively affected the sensory attributes of the fillets and sensory quality was largely maintained for at least 21 days of chilled storage. Although slightly lower sensory and texture scores were obtained for frozen-thawed smoked fillets, they remained within acceptable limits throughout the period of cold storage. The shelf-life of smoked Atlantic mackerel deep-skinned fillets stored at 1°C is, therefore, assessed to be at least 21 days. Well-fed Atlantic mackerel is suitable for developing high-quality and stable smoked fillet products from both fresh and frozen-thawed raw materials., Competing Interests: The authors declare that they do not have any conflict of interest., (© 2024 The Authors. Food Science & Nutrition published by Wiley Periodicals LLC.)
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- 2024
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6. Epidemiological investigations of diarrhea in children in Praia city, Cape Verde.
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Colito DA, Dorta-Guerra R, Da Costa Lima HS, Pina C, Gonçalves D, Valladares B, and Foronda P
- Abstract
Introduction: Diarrheal disease is a major cause of infant mortality and morbidity in Africa and results primarily from contaminated food and water sources, but its prevalence predictors in Cape Verde are not completely known. For this reason, this study aimed to identify the etiological agents of diarrhea in Cape Verdean children and assess its associated risk factors., Methods: A survey questionnaire was used, and a total of 105 stool samples from children with diarrhea aged 0-12 years at the Central Hospital of Praia (Santiago, Cape Verde) were analyzed. The analyses were carried out using Biofire FilmArray Gastrointestinal Panels. Possible risk factors for these pathogens were analyzed using logistic regression, chi-square tests, or Fisher's exact test., Results: Among the bacteria, enteroaggregative Escherichia coli (45.71%; 95% CI: 36.71-56.70), enteropathogenic E. coli (40%; 95% CI: 30.56-50.02), Shigella/enteroinvasive E. coli (29.52%; 95% CI: 21.02-39.22), E. coli enterotoxigenic (12.38%; 95% CI: 6.76-20.24), Campylobacter sp. (10.48%; 95% CI: 5.35-1.97), Vibrio sp. (4.76%; 95% CI: 1.56-10.76), Clostridioides difficile (3.81%; 95% CI: 1.05-9.47), Vibrio cholerae (2.86%; 0.59-8.12), Shiga-like toxin-producing E. coli (2.86%; 0.59-8.12) and Salmonella sp. (0.95%; 0.02-5.19) were identified; four viruses, Rotavirus A (28.57%; 95% CI: 20.18-38.21), Sapovirus I. II. IV and V (11.43%; 95% CI: 6.05-19.11), Norovirus GI.GII (6.67%; 95% CI: 2.72-13.25) and Adenovirus F 40.41 (6.67%; 95% CI: 2.72-13.25) were also observed. All the pathogens detected in this study were found in coinfections. Significant associations with risk factors were found; specifically, having a bathroom at home reduced the risk of Campylobacter sp., having animals at home increased the risk of Shigella /EIEC infection, and drinking bottled water reduced the risk of Sapovirus infection., Discussion: From the findings of this study, it can be concluded that, in Cape Verde, there is a high prevalence and diversity of pathogens among children. Our results could help to establish an adequate diagnosis and effective treatments for diarrheal disease., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Colito, Dorta-Guerra, Da Costa Lima, Pina, Gonçalves, Valladares and Foronda.)
- Published
- 2022
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7. Correlates of the Physical Activity Decline during Childhood.
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Pereira S, Reyes AC, Chaves R, Santos C, Vasconcelos O, Tani GO, Katzmarzyk PT, Baxter-Jones A, and Maia J
- Subjects
- Humans, Child, Male, Female, Child, Preschool, Body Mass Index, Exercise, Schools
- Abstract
Purpose: This study aimed to describe longitudinal trends in children's moderate-to-vigorous physical activity (MVPA) and to investigate associations with individual, familial, and school characteristics., Methods: A sample of 341 Portuguese children age 5-10 yr (173 girls) from six age cohorts was followed over 3 yr using a mixed-longitudinal design. Physical activity, body mass index (BMI), gross motor coordination, and musculoskeletal fitness were assessed annually. Information on socioeconomic status and school characteristics was collected and analyzed with mixed models., Results: MVPA shows a similar declining trend in both sexes, but on average, boys exceeded the World Health Organization recommendations of 60 min·d -1 . The best model showed that boys spend, on average, more time in MVPA than girls. Children with lower BMI are less prone to the decline in MVPA, whereas higher levels of musculoskeletal fitness were associated with lower declines in MVPA. Of all school characteristics, only playground dimension was related to MVPA decreasing trajectories., Conclusions: MVPA systematically declines from 5 to 10 yr of age in both boys and girls, but boys remained more active than girls across the age range. The best predictors of MVPA decline are sex, BMI, musculoskeletal fitness, and school playground dimension., (Copyright © 2022 by the American College of Sports Medicine.)
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- 2022
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8. Study for Recycling Water Treatment Membranes and Compnents towards a Circular Economy-Case of Macaronesia Area.
- Author
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Tavares T, Leon F, Vaswani J, Peñate B, and Ramos-Martín A
- Abstract
Desalination is an opportunity to get fresh water for irrigation and for drinking. Reverse Osmosis (RO) for sea water desalination is a solution for the high demand for water in Atlantic islands. The most efficient process to get desalinated water is RO; however, it is necessary to study what to do with the RO membranes used at the end of their life. This paper confirms the possibility to recycle them. The main categories of recycling by thermal processing commonly used in the industry include incineration and pyrolysis to produce energy, gas and fuel. These processes can be applied to mixed plastic waste, such as the combination of materials used in the manufacture of RO membranes. Recycling RO elements from desalination plants is shown to be an opportunity and pioneering initiatives are already underway in Europe. Energy recovery, via incineration, is feasible nowadays and it is a possibility to recycle RO membranes. On the other hand, the recycling of RO elements, via the pyrolytic industry, for fuel production could be centralized in a new industry already planned in the Macaronesia area and all obsolete osmosis membranes could be sent there for recycling. Recycling RO membranes is a very important opportunity for the environment and economy of the zone. This is a new business in water treatments with membranes, very interesting for decreasing the residues and the carbon footprint. The importance of this work is applied to sea water membranes, brackish water ones, and also wastewater tertiaries RO elements at the end of their life.
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- 2022
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9. The Covid-19 pandemic reinforces the need for sustainable health planning.
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Garcia AC, Beja A, Cupertino de Barros FP, Delgado AP, and Ferrinho P
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- Health Planning, Humans, SARS-CoV-2, Sustainable Development, United States, COVID-19, Pandemics prevention & control
- Abstract
The 2030 Agenda for Sustainable Development highlighted the growing attention to the adequacy of health planning models to sustainable development. A re-reading of the results of a round table debate on "sustainable planning", which took place at the 5th National Congress of Tropical Medicine (Portugal, 2019) under a participant observation strategy, framed by the findings of a "synthesis of better evidence" literature review and cross-referenced with the reflections of different authors and experts about the momentum created by the COVID-19 pandemic, underlined the challenges to sustainable health planning that have emerged and are projected beyond the current pandemic context. Variable perceptions of the term "sustainable health development", leading to the potential loss of their relevance in guiding the elaboration of policies and strategic plans, and the potential higher effectiveness of the participatory approaches of health planning in achieving sustainable health were highlighted in the debate and literature, in general and in public health emergency contexts. Those results gained new relevance during the current COVID-19 pandemic, bringing back to the forefront a reflection of the inadequate planning framework that has usually been used to understand and respond to global health challenges, despite the already existing experience, evidence and support instruments., (© 2021 John Wiley & Sons Ltd.)
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- 2022
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10. Premature mortality attributable to COVID-19: potential years of life lost in 17 countries around the world, January-August 2020.
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Ugarte MP, Achilleos S, Quattrocchi A, Gabel J, Kolokotroni O, Constantinou C, Nicolaou N, Rodriguez-Llanes JM, Huang Q, Verstiuk O, Pidmurniak N, Tao JW, Burström B, Klepac P, Erzen I, Chong M, Barron M, Hagen TP, Kalmatayeva Z, Davletov K, Zucker I, Kaufman Z, Kereselidze M, Kandelaki L, Le Meur N, Goldsmith L, Critchley JA, Pinilla MA, Jaramillo GI, Teixeira D, Goméz LF, Lobato J, Araújo C, Cuthbertson J, Bennett CM, Polemitis A, Charalambous A, and Demetriou CA
- Subjects
- Aged, Brazil, Female, Humans, Life Expectancy, Male, Mortality, Mortality, Premature, Pandemics, SARS-CoV-2, United States, COVID-19
- Abstract
Background: Understanding the impact of the burden of COVID-19 is key to successfully navigating the COVID-19 pandemic. As part of a larger investigation on COVID-19 mortality impact, this study aims to estimate the Potential Years of Life Lost (PYLL) in 17 countries and territories across the world (Australia, Brazil, Cape Verde, Colombia, Cyprus, France, Georgia, Israel, Kazakhstan, Peru, Norway, England & Wales, Scotland, Slovenia, Sweden, Ukraine, and the United States [USA])., Methods: Age- and sex-specific COVID-19 death numbers from primary national sources were collected by an international research consortium. The study period was established based on the availability of data from the inception of the pandemic to the end of August 2020. The PYLL for each country were computed using 80 years as the maximum life expectancy., Results: As of August 2020, 442,677 (range: 18-185,083) deaths attributed to COVID-19 were recorded in 17 countries which translated to 4,210,654 (range: 112-1,554,225) PYLL. The average PYLL per death was 8.7 years, with substantial variation ranging from 2.7 years in Australia to 19.3 PYLL in Ukraine. North and South American countries as well as England & Wales, Scotland and Sweden experienced the highest PYLL per 100,000 population; whereas Australia, Slovenia and Georgia experienced the lowest. Overall, males experienced higher PYLL rate and higher PYLL per death than females. In most countries, most of the PYLL were observed for people aged over 60 or 65 years, irrespective of sex. Yet, Brazil, Cape Verde, Colombia, Israel, Peru, Scotland, Ukraine, and the USA concentrated most PYLL in younger age groups., Conclusions: Our results highlight the role of PYLL as a tool to understand the impact of COVID-19 on demographic groups within and across countries, guiding preventive measures to protect these groups under the ongoing pandemic. Continuous monitoring of PYLL is therefore needed to better understand the burden of COVID-19 in terms of premature mortality., (© 2022. The Author(s).)
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- 2022
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11. Intestinal parasites among children with diarrhoea from Santiago (Cape Verde).
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Colito DA, Dorta-Guerra R, Da Costa Lima HS, Pina C, Gonsalvez D, Valladares B, and Foronda P
- Subjects
- Humans, Child, Preschool, Male, Infant, Child, Female, Feces parasitology, Feces microbiology, Prevalence, Diarrhea etiology, Intestinal Diseases, Parasitic complications, Intestinal Diseases, Parasitic epidemiology
- Abstract
Competing Interests: Competing interests: None declared.
- Published
- 2021
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12. Gender and Environment in the Interior of Santiago Island/Cape Verde: Sand Harvesting From Women Heads of Families.
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Vieira MS and Rocha EV
- Abstract
Cape Verde is an island country and Sahelian, where the climatic conditions cause a rainfall deficit originating dry periods causing a fragile agricultural development. The rural world is facing various problems such as lack of land for cultivation, lack of water and soil erosion. The " apanha de areia " (sand haversting) refers to the extraction of sand and gravel from the sea and rocks. Although it is considered as an environmental crime, the activity is carried for generations and supplies the civil construction business of the country. This study analyze this activity from the perspective of women from the interior of Santiago, in the locality of Charco, in the municipality of Santa Catarina. The research was carried out based on an ethnography of long duration, with spaced field visits, since January 2009 and the monitoring of environmental and gender policies in Cape Verde. As results, we highlight women's agency in the face of a context of growing social inequalities., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Vieira and Rocha.)
- Published
- 2021
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13. Comparison of Commercial ELISA Kits to Confirm the Absence of Transmission in Malaria Elimination Settings.
- Author
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van den Hoogen LL, Bareng P, Alves J, Reyes R, Macalinao M, Rodrigues JM, Fernandes JM, Goméz LF, Hall T, Singh SK, Fornace K, Luchavez J, Kitchen A, Chiodini P, Espino F, Tetteh KKA, Stresman G, Sepúlveda N, and Drakeley C
- Subjects
- Cabo Verde, Enzyme-Linked Immunosorbent Assay, Gambia, Humans, Philippines, Sensitivity and Specificity, Malaria diagnosis
- Abstract
Background: Antimalarial antibody measurements are useful because they reflect historical and recent exposure to malaria. As such, they may provide additional information to assess ongoing transmission in low endemic or pre-elimination settings where cases are rare. In addition, the absence of antibody responses in certain individuals can indicate the cessation of transmission. Commercial malaria enzyme-linked immunosorbent assays (ELISA) detect antimalarial antibodies and are commonly used to screen blood donations for possible malaria infection. However, there is no standardized test to detect antimalarial antibodies for epidemiological use. Here we compared five commercially available ELISA kits (Trinity Biotech, newbio, DiaPro, Cellabs, and NovaTec) in search of a standardized tool for supporting claims of absence of malaria transmission. For comparison, a research-based (RB) ELISA protocol was performed alongside the commercial kits. Results: The commercial kits were first compared using serum samples from known malaria-unexposed individuals ( n = 223) and Toxoplasma -infected individuals ( n = 191) to assess specificity and cross-reactivity against non-malaria infections. In addition, 134 samples from ≥10-year-olds collected in a hyperendemic region in the Gambia in the early 1990s were used to assess sensitivity. Three out of five kits showed high sensitivity (90-92%), high specificity (98-99%), low cross-reactivity (0-3%) and were considered user-friendly (Trinity Biotech, newbio and NovaTec). Two of these kits (Trinity Biotech and NovaTec) were taken forward for epidemiological evaluation and results were compared to those using the RB-ELISA. Samples from two pre-elimination settings (Praia, Cape Verde; n = 1,396, and Bataan, the Philippines; n = 1,824) were tested. Serological results from both the Trinity Biotech kit and the RB-ELISA concurred with recent passively detected case counts in both settings. Results from the Trinity Biotech kit reflected a significant decrease in the number of reported cases in Bataan in the 1990s better than the RB-ELISA. Results from the NovaTec kit did not reflect transmission patterns in either setting. Conclusion: The Trinity Biotech commercial ELISA kit was considered reliable for epidemiological use and accurately described transmission patterns in two (previously) malaria endemic settings. The use of this simple and standardized serological tool may aid national control and elimination programs by confirming that regions are free from malaria., (Copyright © 2020 van den Hoogen, Bareng, Alves, Reyes, Macalinao, Rodrigues, Fernandes, Goméz, Hall, Singh, Fornace, Luchavez, Kitchen, Chiodini, Espino, Tetteh, Stresman, Sepúlveda and Drakeley.)
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- 2020
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14. Durability and Time-Dependent Properties of Low-Cement Concrete.
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Robalo K, Soldado E, Costa H, Carvalho L, do Carmo R, and Júlio E
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The sustainability concerns of concrete construction are focused both on the materials' eco-efficiency and on the structures' durability. The present work focuses on the characterization of low cement concrete (LCC), regarding time-dependent and durability properties. LCC studies which explore the influence of the formulation parameters, such as the W/C (water/cement ratio), W/Ceq, (which represents the mass ratio between water and equivalent cement), W/B (water/binder) ratio, and the reference curves, on the aforementioned properties are limited. Thus, several LCC mixtures were formulated considering two dosages of binder powder, 350 and 250 kg/m
3 , the former with very plastic consistency and the latter with dry consistency, which were combined with a large spectrum of cement replacement rates (up to 70%), through adding fly ash and limestone filler, and with different compactness levels. The main objectives were to study the influence of the formulation parameters on the properties: shrinkage and creep, accelerated carbonation and water absorption, by capillarity, and by immersion. The lifetime of structures produced with the studied LCC was estimated, considering the durability performance, regarding the carbonation effect on the possible corrosion of the steel reinforcement. LCC mixtures with reduced cement dosage and high compactness, despite the high W/C ratios, have low shrinkage and those with higher strength have reduced creep, however depending on W/Ceq ratio. Those mixtures can be formulated and produced presenting good performance regarding carbonation resistance and, consequently, a long lifetime, which is mandatory for a sustainable construction. LCC with 175 kg/m3 of cement dosage is an example with higher lifetime than current concrete with 250 kg/m3 of cement; depending on the XC exposure classes (corrosion induced by carbonation), the amount of cement can be reduced between 37.5% and 42%, since the LCC with 175 kg/m3 of cement allows reducing the concrete cover below the minimum recommended, ensuring simultaneously the required lifetime for current and special structures.- Published
- 2020
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15. First Report of the Lesion Nematodes: Pratylenchus Brachyurus and Pratylenchus Delattrei on Tomato ( Solanum Lycopersicum L.) Plants in Cape Verde.
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Flis Ł, Dobosz R, Rybarczyk-Mydłowska K, Wasilewska-Nascimento B, Kubicz M, and Winiszewska G
- Abstract
Roots of Solanum lycopersicum L. were collected in growing season of year 2015, on the island of Santiago in Cape Verde. Morphological, morphometric and molecular (18S rDNA and 28S rDNA) studies revealed the presence of Pratylenchus brachyurus and P. delattrei in root systems and root zones of tomato plants. To our knowledge, this is the first record of the occurrence of these nematode species in Cape Verde., (© 2018 Ł. Flis, R. Dobosz, K. Rybarczyk-Mydłowska, B. Wasilewska-Nascimento, M. Kubicz, G. Winiszewska, published by Sciendo.)
- Published
- 2018
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16. Metastability for discontinuous dynamical systems under Lévy noise: Case study on Amazonian Vegetation.
- Author
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Serdukova L, Zheng Y, Duan J, and Kurths J
- Subjects
- Biostatistics, Models, Theoretical, Rainforest, Tropical Climate, Environmental Exposure, Plant Dispersal, Population Dynamics, Trees growth & development
- Abstract
For the tipping elements in the Earth's climate system, the most important issue to address is how stable is the desirable state against random perturbations. Extreme biotic and climatic events pose severe hazards to tropical rainforests. Their local effects are extremely stochastic and difficult to measure. Moreover, the direction and intensity of the response of forest trees to such perturbations are unknown, especially given the lack of efficient dynamical vegetation models to evaluate forest tree cover changes over time. In this study, we consider randomness in the mathematical modelling of forest trees by incorporating uncertainty through a stochastic differential equation. According to field-based evidence, the interactions between fires and droughts are a more direct mechanism that may describe sudden forest degradation in the south-eastern Amazon. In modeling the Amazonian vegetation system, we include symmetric α-stable Lévy perturbations. We report results of stability analysis of the metastable fertile forest state. We conclude that even a very slight threat to the forest state stability represents L´evy noise with large jumps of low intensity, that can be interpreted as a fire occurring in a non-drought year. During years of severe drought, high-intensity fires significantly accelerate the transition between a forest and savanna state.
- Published
- 2017
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17. Transitions in a genetic transcriptional regulatory system under Lévy motion.
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Zheng Y, Serdukova L, Duan J, and Kurths J
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- Feedback, Models, Genetic, Noise, Probability, Stochastic Processes, Time Factors, Gene Expression Regulation, Motion, Transcription, Genetic
- Abstract
Based on a stochastic differential equation model for a single genetic regulatory system, we examine the dynamical effects of noisy fluctuations, arising in the synthesis reaction, on the evolution of the transcription factor activator in terms of its concentration. The fluctuations are modeled by Brownian motion and α-stable Lévy motion. Two deterministic quantities, the mean first exit time (MFET) and the first escape probability (FEP), are used to analyse the transitions from the low to high concentration states. A shorter MFET or higher FEP in the low concentration region facilitates such a transition. We have observed that higher noise intensities and larger jumps of the Lévy motion shortens the MFET and thus benefits transitions. The Lévy motion activates a transition from the low concentration region to the non-adjacent high concentration region, while Brownian motion can not induce this phenomenon. There are optimal proportions of Gaussian and non-Gaussian noises, which maximise the quantities MFET and FEP for each concentration, when the total sum of noise intensities are kept constant. Because a weaker stability indicates a higher transition probability, a new geometric concept is introduced to quantify the basin stability of the low concentration region, characterised by the escaping behaviour.
- Published
- 2016
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18. Stochastic basins of attraction for metastable states.
- Author
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Serdukova L, Zheng Y, Duan J, and Kurths J
- Abstract
Basin of attraction of a stable equilibrium point is an effective concept for stability analysis in deterministic systems; however, it does not contain information on the external perturbations that may affect it. Here we introduce the concept of stochastic basin of attraction (SBA) by incorporating a suitable probabilistic notion of basin. We define criteria for the size of the SBA based on the escape probability, which is one of the deterministic quantities that carry dynamical information and can be used to quantify dynamical behavior of the corresponding stochastic basin of attraction. SBA is an efficient tool to describe the metastable phenomena complementing the known exit time, escape probability, or relaxation time. Moreover, the geometric structure of SBA gives additional insight into the system's dynamical behavior, which is important for theoretical and practical reasons. This concept can be used not only in models with small noise intensity but also with noise whose amplitude is proportional or in general is a function of an order parameter. As an application of our main results, we analyze a three potential well system perturbed by two types of noise: Brownian motion and non-Gaussian α-stable Lévy motion. Our main conclusions are that the thermal fluctuations stabilize the metastable system with an asymmetric three-well potential but have the opposite effect for a symmetric one. For Lévy noise with larger jumps and lower jump frequencies ( α=0.5) metastability is enhanced for both symmetric and asymmetric potentials.
- Published
- 2016
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