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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
Showing 1 - 200 of 265 Journals sorted alphabetically
AAS Open Research     Open Access   (Followers: 1)
Accountability in Research: Policies and Quality Assurance     Hybrid Journal   (Followers: 18)
Acta Materialia Transilvanica     Open Access  
Acta Nova     Open Access  
Acta Scientifica Malaysia     Open Access   (Followers: 1)
Acta Scientifica Naturalis     Open Access   (Followers: 4)
Adıyaman University Journal of Science     Open Access  
Advanced Science     Open Access   (Followers: 12)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 4)
Advanced Theory and Simulations     Hybrid Journal   (Followers: 4)
Advances in Research     Open Access  
Advances in Science and Technology     Full-text available via subscription   (Followers: 16)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 7)
Afrique Science : Revue Internationale des Sciences et Technologie     Open Access   (Followers: 1)
AFRREV STECH : An International Journal of Science and Technology     Open Access   (Followers: 3)
Alfarama Journal of Basic & Applied Sciences     Open Access  
American Academic & Scholarly Research Journal     Open Access   (Followers: 4)
American Journal of Applied Sciences     Open Access   (Followers: 21)
American Journal of Humanities and Social Sciences     Open Access   (Followers: 13)
ANALES de la Universidad Central del Ecuador     Open Access   (Followers: 1)
Anales del Instituto de la Patagonia     Open Access  
Applied Mathematics and Nonlinear Sciences     Open Access   (Followers: 1)
Apuntes de Ciencia & Sociedad     Open Access  
Arab Journal of Basic and Applied Sciences     Open Access  
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 1)
Archives Internationales d'Histoire des Sciences     Partially Free   (Followers: 5)
Archives of Current Research International     Open Access  
ARO. The Scientific Journal of Koya University     Open Access  
ARPHA Conference Abstracts     Open Access   (Followers: 1)
ARPHA Proceedings     Open Access  
ArtefaCToS : Revista de estudios sobre la ciencia y la tecnología     Open Access  
Asian Journal of Advanced Research and Reports     Open Access  
Asian Journal of Scientific Research     Open Access   (Followers: 2)
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 5)
Australian Field Ornithology     Full-text available via subscription   (Followers: 2)
Australian Journal of Social Issues     Hybrid Journal   (Followers: 6)
Avrasya Terim Dergisi     Open Access  
Bangladesh Journal of Scientific Research     Open Access  
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 1)
Berichte Zur Wissenschaftsgeschichte     Hybrid Journal   (Followers: 11)
BIBECHANA     Open Access  
Bilge International Journal of Science and Technology Research     Open Access  
Bioethics Research Notes     Full-text available via subscription   (Followers: 16)
BJHS Themes     Open Access  
Black Sea Journal of Engineering and Science     Open Access  
Borneo Journal of Resource Science and Technology     Open Access  
Bulletin de la Société Royale des Sciences de Liège     Open Access  
Bulletin of the National Research Centre     Open Access  
Butlletí de la Institució Catalana d'Història Natural     Open Access  
Chain Reaction     Full-text available via subscription  
Ciencia Amazónica (Iquitos)     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencia Ergo Sum     Open Access  
Ciência ET Praxis     Open Access  
Ciencia y Tecnología     Open Access  
Ciencias Holguin     Open Access   (Followers: 1)
CienciaUAT     Open Access  
Citizen Science : Theory and Practice     Open Access   (Followers: 2)
Communications Faculty of Sciences University of Ankara Series A2-A3 Physical Sciences and Engineering     Open Access  
Communications in Applied Sciences     Open Access  
Comunicata Scientiae     Open Access  
ConCiencia     Open Access  
Conference Papers in Science     Open Access  
Configurations     Full-text available via subscription   (Followers: 11)
COSMOS     Hybrid Journal   (Followers: 1)
Crea Ciencia Revista Científica     Open Access  
Cuadernos de Investigación UNED     Open Access  
Current Issues in Criminal Justice     Hybrid Journal   (Followers: 13)
Current Research in Geoscience     Open Access   (Followers: 5)
Dalat University Journal of Science     Open Access  
Data     Open Access   (Followers: 4)
Data Curation Profiles Directory     Open Access   (Followers: 8)
Dhaka University Journal of Science     Open Access  
Diálogos Interdisciplinares     Open Access  
Digithum     Open Access   (Followers: 2)
Discover Sustainability     Open Access   (Followers: 3)
Einstein (São Paulo)     Open Access  
Ekaia : EHUko Zientzia eta Teknologia aldizkaria     Open Access  
Elkawnie : Journal of Islamic Science and Technology     Open Access  
Emergent Scientist     Open Access  
Enhancing Learning in the Social Sciences     Open Access   (Followers: 7)
Enseñanza de las Ciencias : Revista de Investigación y Experiencias Didácticas     Open Access  
Entramado     Open Access  
Entre Ciencia e Ingeniería     Open Access  
Epiphany     Open Access   (Followers: 1)
Estação Científica (UNIFAP)     Open Access  
Ethiopian Journal of Education and Sciences     Open Access   (Followers: 5)
Ethiopian Journal of Science and Technology     Open Access  
Ethiopian Journal of Sciences and Sustainable Development     Open Access  
European Online Journal of Natural and Social Sciences     Open Access   (Followers: 4)
European Scientific Journal     Open Access   (Followers: 5)
Evidência - Ciência e Biotecnologia - Interdisciplinar     Open Access  
Exchanges : the Warwick Research Journal     Open Access   (Followers: 1)
Experimental Results     Open Access   (Followers: 1)
Facets     Open Access  
Fides et Ratio : Revista de Difusión Cultural y Científica     Open Access  
Fırat University Turkish Journal of Science & Technology     Open Access  
Fontanus     Open Access   (Followers: 1)
Forensic Science Policy & Management: An International Journal     Hybrid Journal   (Followers: 239)
Frontiers for Young Minds     Open Access  
Frontiers in Climate     Open Access   (Followers: 4)
Frontiers in Science     Open Access   (Followers: 1)
Fundamental Research     Open Access  
Futures & Foresight Science     Hybrid Journal   (Followers: 1)
Gaudium Sciendi     Open Access  
Gazi University Journal of Science     Open Access  
Ghana Studies     Full-text available via subscription   (Followers: 15)
Global Journal of Pure and Applied Sciences     Full-text available via subscription  
Global Journal of Science Frontier Research     Open Access   (Followers: 1)
Globe, The     Full-text available via subscription   (Followers: 4)
HardwareX     Open Access  
Heidelberger Jahrbücher Online     Open Access  
Heliyon     Open Access  
Himalayan Journal of Science and Technology     Open Access  
History of Science and Technology     Open Access   (Followers: 5)
Hoosier Science Teacher     Open Access  
Impact     Open Access   (Followers: 1)
Indian Journal of History of Science     Hybrid Journal  
Indonesian Journal of Fundamental Sciences     Open Access  
Indonesian Journal of Science and Mathematics Education     Open Access   (Followers: 2)
Indonesian Journal of Science and Technology     Open Access  
Ingenieria y Ciencia     Open Access   (Followers: 1)
Innovare : Revista de ciencia y tecnología     Open Access  
Instruments     Open Access  
Integrated Research Advances     Open Access  
Interciencia     Open Access  
Interface Focus     Full-text available via subscription  
International Annals of Science     Open Access  
International Archives of Science and Technology     Open Access  
International Journal of Academic Research in Business, Arts & Science     Open Access  
International Journal of Advanced Multidisciplinary Research and Review     Open Access  
International Journal of Applied Science     Open Access  
International Journal of Basic and Applied Sciences     Open Access   (Followers: 1)
International Journal of Computational and Experimental Science and Engineering (IJCESEN)     Open Access  
International Journal of Culture and Modernity     Open Access   (Followers: 2)
International Journal of Engineering, Science and Technology     Open Access  
International Journal of Engineering, Technology and Natural Sciences     Open Access  
International Journal of Innovation and Applied Studies     Open Access   (Followers: 4)
International Journal of Innovative Research and Scientific Studies     Open Access   (Followers: 1)
International Journal of Network Science     Hybrid Journal   (Followers: 3)
International Journal of Recent Contributions from Engineering, Science & IT     Open Access  
International Journal of Research in Science     Open Access   (Followers: 1)
International Journal of Social Sciences and Management     Open Access   (Followers: 2)
International Journal of Technology Policy and Law     Hybrid Journal   (Followers: 8)
International Letters of Social and Humanistic Sciences     Open Access  
International Science and Technology Journal of Namibia     Open Access   (Followers: 1)
International Scientific and Vocational Studies Journal     Open Access  
InterSciencePlace     Open Access  
Investiga : TEC     Open Access  
Investigación Joven     Open Access  
Investigacion y Ciencia     Open Access   (Followers: 1)
Iranian Journal of Science and Technology, Transactions A : Science     Hybrid Journal  
iScience     Open Access   (Followers: 1)
Issues in Science & Technology     Free   (Followers: 8)
Ithaca : Viaggio nella Scienza     Open Access  
J : Multidisciplinary Scientific Journal     Open Access  
Jaunujų mokslininkų darbai     Open Access   (Followers: 1)
Journal de la Recherche Scientifique de l'Universite de Lome     Full-text available via subscription  
Journal of Advanced Research     Open Access   (Followers: 2)
Journal of Al-Qadisiyah for Pure Science     Open Access  
Journal of Alasmarya University     Open Access  
Journal of Analytical Science & Technology     Open Access   (Followers: 4)
Journal of Applied Science and Technology     Full-text available via subscription   (Followers: 1)
Journal of Applied Sciences and Environmental Management     Open Access   (Followers: 1)
Journal of Big History     Open Access   (Followers: 3)
Journal of Composites Science     Open Access   (Followers: 4)
Journal of Diversity Management     Open Access   (Followers: 4)
Journal of Indian Council of Philosophical Research     Hybrid Journal  
Journal of Institute of Science and Technology     Open Access  
Journal of Integrated Science and Technology     Open Access  
Journal of King Saud University - Science     Open Access  
Journal of Mathematical and Fundamental Sciences     Open Access  
Journal of Natural Sciences Research     Open Access   (Followers: 1)
Journal of Negative and No Positive Results     Open Access  
Journal of Responsible Technology     Open Access  
Journal of Science (JSc)     Open Access  
Journal of Science and Engineering     Open Access   (Followers: 1)
Journal of Science and Technology     Open Access   (Followers: 2)
Journal of Science and Technology     Open Access   (Followers: 1)
Journal of Science and Technology (Ghana)     Open Access   (Followers: 3)
Journal of Science and Technology Policy Management     Hybrid Journal   (Followers: 1)
Journal of Science Foundation     Open Access   (Followers: 1)
Journal of Science of the University of Kelaniya Sri Lanka     Open Access  
Journal of Scientific Research     Open Access  
Journal of Scientific Research and Reports     Open Access  
Journal of Scientometric Research     Open Access   (Followers: 21)
Journal of Shanghai Jiaotong University (Science)     Hybrid Journal  
Journal of Social Science Research     Open Access   (Followers: 2)
Journal of Taibah University for Science     Open Access  
Journal of the Asiatic Society of Bangladesh, Science     Open Access  
Journal of the Ghana Science Association     Full-text available via subscription   (Followers: 3)
Journal of the History of Ideas     Full-text available via subscription   (Followers: 149)
Journal of the Indian Institute of Science     Hybrid Journal   (Followers: 4)
Journal of the National Science Foundation of Sri Lanka     Open Access  
Journal of the Royal Society of New Zealand     Hybrid Journal   (Followers: 48)
Journal of the South Carolina Academy of Science     Open Access  
Journal of Unsolved Questions     Open Access  
Jurnal Ilmiah Ilmu Terapan Universitas Jambi : JIITUJ     Open Access  
Jurnal Matematika, Sains, Dan Teknologi     Open Access  
Jurnal MIPA     Open Access  

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Cuadernos de Investigación UNED
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1659-4266 - ISSN (Online) 1659-4266
Published by Universidad Estatal a Distancia Homepage  [6 journals]
  • First pages 14(2)

    • Authors: UNED Research Journal
      Abstract: First pages 14(2) December 2022
      PubDate: 2022-11-30
      DOI: 10.22458/urj.v14i2.4524
      Issue No: Vol. 14, No. 2 (2022)
       
  • Foliar spray of seaweed extract and fertilizers on sweet pepper (Capsicum
           annuum)

    • Authors: Werner Salazar-Salazar, José Eladio Monge-Pérez, Michelle Loría-Coto
      Abstract: Introduction: Seaweed extracts have biostimulant activities that improve growth and yield in many crops, and can improve mineral absorption. Objective: to evaluate the effects of foliar spray of seaweed extract and fertilizers (treatments: seaweed extract (SE); fertilizers (FF); seaweed extract+fertilizers (SE+FF); and control-C) on the yield and quality of sweet pepper grown under greenhouse conditions. Methods: The crop was managed in a coconut fiber substrate and with fertigation. Evaluated variables were: number of fruits per plant, fruit weight (g), yield (ton/ha), percentage of total soluble solids (°Brix), chlorophyll content (atLEAF), leaf area (cm2), leaf dry weight (g), specific leaf weight (mg/cm2), plant height (cm), and stem diameter (mm). Treatments were applied from 14 days after transplant (ddt), and were carried out weekly until the end of the trial (154 ddt). Results: Treatments SE and SE+FF produced a higher number of commercial and total fruits per plant, as well as higher commercial and total yields when compared to treatments FF and C. The SE+FF treatment produced a greater fruit weight, compared to treatment C, both at a commercial and total level. No significant differences between treatments were observed for the following variables: leaf area, leaf dry weight, leaf specific weight, plant height and stem diameter. Conclusion: The use of the seaweed extract (SE) produced the highest total and commercial yield at the lowest cost, and thus its utilization is recommended under the trial conditions; on the other hand, the application of foliar fertilizers (FF) under the same conditions did not improve neither the yield of sweet peppers nor their quality.
      PubDate: 2022-11-04
      DOI: 10.22458/urj.v14i2.4299
      Issue No: Vol. 14, No. 2 (2022)
       
  • The Amazon sailfin catfish Pterygoplichthys disjunctivus x pardalis
           (Siluriformes: Loricariidae) in Panamá

    • Authors: Rigoberto González Gutiérrez
      Abstract: Introduction: Despite having a rich and diverse native freshwater fish fauna, exotic species have been introduced to Panama since the 20th century. Objective: To report its presence in the fresh waters of Panama of a newly recorded exotic fish. Methods: Specimens were caught with gillnet in Gatun lake, on September 30, 2017. Results: Three specimens with average standard length and weight of 233mm and 307g, respectively, were identified as Pterygoplichthys disjunctivus x pardalis. This armored catfish, native to the Amazon basin, is breeding in Gatun and may threaten local species. Conclusion: The exotic fish Pterygoplichthys disjunctivus x pardalis has a reproductive population in Gatun Lake, Panama.
      PubDate: 2022-11-04
      DOI: 10.22458/urj.v14i2.4352
      Issue No: Vol. 14, No. 2 (2022)
       
  • Effects of a natural preservative from sugarcane, and sodium lactate, on
           characteristics and acceptance of pressed ham

    • Authors: Valeria Brenes Rodríguez, Alejandro Chacón-Villalobos, Yorleny Araya-Quesada
      Abstract: ABSTRACT. Introduction: The reformulation of processed meat products is an important strategy in international plans to reduce sodium consumption. Objective: To compare the preserving action of sodium lactate with that of Proteria™ CV, based on sugarcane. Methods: We tested the preservtives during the refrigerated storage of pressed ham, in four combinations: sodium lactate, Proteria™ CV, a 50% - 50% mix of both, and no preservative as control. We evaluated total aerobic mesophilic microorganisms count, lactic acid bacteria count, pH, syneresis, texture, color and oxidative rancidity; as well as a discriminative sensory evaluation and a liking test with 100 consumers. Results: There were no differences in physical, chemical, and microbiological parameters. Consumers, however, reported a sensory difference. 67% of panelists liked all samples but prefered Proteria™ CV; 21% showed no preference but disliked the mixture; and 12% preferred the mixture. Conclusion: Proteria™ CV achieves a 30% reduction in sodium, and is accepted by consumers without generating significant quality changes.
      PubDate: 2022-11-02
      DOI: 10.22458/urj.v14i2.4200
      Issue No: Vol. 14, No. 2 (2022)
       
  • Potato residues as an aid to aluminum sulfate in water clarification

    • Authors: Lizbeth Ynofuente Quispe, Magali Flores Condori, Juan Eduardo Vigo Rivera
      Abstract: Introduction: Aluminum sulfate, or iron salts, are used as coagulantsto eliminate suspended particles that produce turbidity in water for human consumption, but the process can be improved with other componets. Objective: To evaluate the use of potato peels as an aid to aluminum sulfate in water clarification. Methodology: We worked with a simulated sample of 40 UNT at 16°C with a pH of 7,16, and the CEPIS method to determine the optimal dose (7 treatments x 9 dosages factorial arrangement). Results: Aluminum sulfate + red potato peel, at 30mg/L produced the lowest turbidity (0,85 UNT at a pH of 6,99, with a removal efficiency of 98%. Aluminum sulfate + black imilla husk (35mg/L) produced a turbidity of 0,90 UNT, pH 6,96, 98% efficiency. Conclusion: Imilla and red potato are useful as a coagulation aid for aluminum sulfate.
      PubDate: 2022-10-24
      DOI: 10.22458/urj.v14i2.4282
      Issue No: Vol. 14, No. 2 (2022)
       
  • New records of Branchiostoma californiense (Amphioxiformes:
           Branchiostomatidae) in El Salvador, Central America

    • Authors: José Enrique Barraza, Verónica Esperanza Melara Pérez
      Abstract: Introduction: Cephalochordates are benthic organisms that represent an important link in the evolution of chordates. Coastal human communities use them as food in some Asian countries. Objective: To register the presence of B. californiense in El Salvador. Methods: We collected specimens during different benthic surveys at Jiquilisco and La Union Bays in April 2018 and November 2019, with a Petite Ponar grab and core in subtidal as well as intertidal sediments, respectively. Results: Ten specimens were collected from sandy-muddy sediments at Jiquilisco and La Union bays. Conclusion: B. californiense inhabits estuarine areas in El Salvador.
      PubDate: 2022-10-24
      DOI: 10.22458/urj.v14i2.4302
      Issue No: Vol. 14, No. 2 (2022)
       
  • Paranormal beliefs in young Salvadoran adults: sociodemographic links,
           socialization agents and perception of anomie

    • Authors: Carlos Iván Orellana
      Abstract: “Paranormal beliefs in young Salvadoran adults: sociodemographic links, socialization agents and perception of anomie” Introduction: Paranormal beliefs are beliefs that are not scientifically accepted. These beliefs, that may constitute tools for personal control and uncertainty reduction, do not seem to have been studied in Central America. Objective: To explore paranormal beliefs in a sample of Salvadoran adults. Methods: 510 participants filled out a survey that included different measurement scales: Paranormal Beliefs, Perception of Anomie, Fear of Crime and Socialization Agents. The Paranormal Belief Scale is made up of three factors: witchcraft, psi-superstition and strange life forms. Results: The most accepted belief was witchcraft. Women, evangelical Christians, and individuals from low-income families, were more accepting of paranormal beliefs, and these correlate with the perception of anomie and fear of crime. Conclusion: Paranormal beliefs in this sample vary individually, reflect social conditions, and are linked to perceptions of threat and uncertainty.
      PubDate: 2022-10-11
      DOI: 10.22458/urj.v14i2.4245
      Issue No: Vol. 14, No. 2 (2022)
       
  • Chemistry of essential oils of the shrub Lippia alba (Verbenaceae) from
           Mexico and Costa Rica

    • Authors: Carlos Chaverri, Feliza Ramón-Farías, José F. Cicció
      Abstract: ABSTRACT: Introduction: Lippia is a Verbenaceous genus of flowering plants, which has about 200 species, distributed throughout the southern USA, Mexico, and Central America to South America. Objective: To study and compare the chemical compositions of the essential oils of L. alba growing in Mexico and Costa Rica. Methods: The essential oils were obtained by hydrodistillation in a Clevenger-type apparatus. The chemical composition of the oils was analyzed by capillary GC-FID and GC-MS using the retention indices on a DB-5 type capillary column in addition to mass spectral fragmentation patterns. Results: A total of 65 compounds were identified in the essential oil samples from both countries, accounting for 96,5-98,1% of the total amount of the oils. The main constituents of the Mexican sample were 1,8-cineole (22,3%), myrcenone (11,2%), myrcene (10,9%), (E)-ocimenone (10,7%), (Z)-ocimenone (7,5%), and sabinene (6,8%), while for essential oil from Costa Rica the major compounds were myrcenone (30,4%), 1,8-cineole (21,4%), myrcene (11,0%), hedycaryol (4,4%), and sabinene (4,3%). Samples from both countries can be classified as belonging to chemotype “tagetenone”. Lippia alba (strong form) from Costa Rica produces essential oil that differs from all other essential oils of L. alba studied to date because it contained the sesquiterpenoids hedycaryol and the isomeric alcohols α-eudesmol, β-eudesmol, and γ-eudesmol. Conclusion: L. alba (strong form) from Costa Rica can be classified as a new subtype of the chemotype “tagetenone” (chemotype II).
      PubDate: 2022-10-07
      DOI: 10.22458/urj.v14i2.4005
      Issue No: Vol. 14, No. 2 (2022)
       
  • Richness, relative abundance and activity of medium and large mammals of a
           reserve under restoration in Costa Rica

    • Authors: Pablo Marín Pacheco , Alison Vega Cambronero, Lucía I. López, José Manuel Mora
      Abstract: ABSTRACT. “Richness, relative abundance and activity of medium and large mammals of a reserve under restoration in Costa Rica”. Introduction: Private protected areas are a valuable complement to national systems of protected areas. The Sierra Zapote Reserve in Abangares, Costa Rica, established in 2000, protects 70 ha of advanced secondary forest, regenerating secondary forest and primary riparian forest. It is expected to favor faunal communities, like medium and large mammals, which are among the species most threatened by habitat loss and fragmentation; nevertheless; there is a lack of recent faunal assessments at Sierra Zapote. Objective: To assess the richness, relative abundance and activity patterns of these mammals in the reserve. Methods: From May 2020 to July 2021, we kept five camera-traps at strategic sites and programmed them to be active 24 hours a day (0,3 seconds between shots). We checked the cameras every one or two months and also extracted temperature and moon phase data. Results: We obtained 758 independent records of mammals with a 2 135-day photo-trapping effort. The most abundant species were Nasua narica (relative abundance index RAI = 14,6, N= 312) and Didelphis marsupialis (RAI = 6,1, N= 130). The least abundant were Herpailurus yagouaroundi and Procyon lotor (RAI = 0,05, N= 1). Most species are nocturnal and only the peccary (Pecari tajacu), the coati (Nasua narica) and the agouti (Dasyprocta punctata) have mostly diurnal activity. The puma (Puma concolor) occurs at the reserve. Conclusion: The activity patterns were as expected; for the reserve size, a richness of 19 species is comparatively high. The presence of the puma, an indicator of good ecosystem health, hints at the importance of the reserve’s restoration process.
      PubDate: 2022-10-07
      DOI: 10.22458/urj.v14i2.4210
      Issue No: Vol. 14, No. 2 (2022)
       
  • Essential oils, phenology and biotic interactions of the invasive plant
           Crassocephalum crepidioides (Asteraceae) in Costa Rica

    • Authors: Carlos Chaverri, Carlos O. Morales, José F. Cicció
      Abstract: ABSTRACT. “Essential oils, phenology and biotic interactions of the invasive plant Crassocephalum crepidioides (Asteraceae) in Costa Rica”. Introduction: Crassocephalum crepidioides (Asteraceae) is an herbaceous species with outstanding ethnobotanical uses in Africa and elsewhere, that has extended invasively in several tropical and subtropical regions around the world. Objective: To identify the chemical composition of the essential oils of C. crepidioides, to observe and measure phenological parameters (growth and development), and to record signs of the interaction of plants with other biotic agents throughout the life cycle in the Central Valley of Costa Rica. Methods: The essential oils were obtained via hydrodistillation in a Clevenger-type apparatus. The chemical composition of the oils was done by capillary gas chromatography (GC/FID and GC/MS). The biological field study was a descriptive account of phenological patterns observed during a year in 45 plants from three places, including vegetative and reproductive phases. Results: The essential oils consisted mainly of terpenoids (91,0 to 98,6%). A total of 231 different compounds were identified in the analyzed samples, corresponding to 94,9-99,3% of the total amount of the oils. The major compounds from the leaf oil were myrcene (67,5%) and β-phellandrene (11,6%), while the stem oil mainly contained myrcene (42,2%) and α-copaene (16,5%). The major constituents of flower oil were myrcene (71,8%) and β-phellandrene (17,2%). In the root oil, (E)-β-farnesene (29,5-46,0%), (Z)-β-farnesene (13,0-15,7%) and (E)-caryophyllene (6,0-6,1%) predominated. The mean height of plants was considerably superior in open and sunny places compared to values in partially shaded habitats. In one of the places, 36% of plants died before completing the life cycle for the most part, due to herbivory that was present in more than 80% of all plants and damaged 100% of their shoot organs (stems, leaves, lateral buds, flower buds, and flowers). November and December were the months with maximal flower anthesis and fruit ripening. Conclusions: This species is recognized as annual, but 2/3 of plants completed their life cycle in 4 to 6 months, and due to herbivory and other environmental factors its propagation shows a considerable reduction.
      PubDate: 2022-10-06
      DOI: 10.22458/urj.v14i2.4079
      Issue No: Vol. 14, No. 2 (2022)
       
  • Length-weight relationships and microhabitat effect on relative health
           condition of mangrove fishes from Chiapas, Mexico

    • Authors: Salvador Santamaria-Damián, Cristian Tovilla-Hernández, Emilio I. RomeroBerny, Wilfredo A. Matamoros
      Abstract: Introduction: The specialized root systems of mangroves provide protection and food resources for young and small fish, and it is known that they are reflected on some health condition and growth characteristics of the fish, but much remains to be learned about this subject in the tropics. Objective: To estimate length-weight relationships for ten bony fish species in two tropical mangroves and to compare the allometry and health condition for three species shared among those mangroves. Methods: Between May and November 2019, we collected 1 500 fish specimens from the roots of two mangroves in Chiapas, Mexico (1 322 fishes in stilt-roots and 188 in pneumatophores). We estimated Length-Weight relations with W=aSLb, and the regression parameters (a and b) were calculated by least-squares; as well as univariate analyses to compare standard length, regression slopes, and relative condition among individuals of Poecilia nelsoni, Poeciliopsis fasciata and Dormitator latifrons. Results: The standard length for all species ranged between 0,7 and 21,5 cm and weight between 0,01 and 209,34 g; the regression b-values varied from 2,844 for P. fasciata and 3,847 for Poeciliopsis pleurospilus. TDetermination coefficients were >0,9 for eight species in stilt-roots and for three species in pneumatophores. Specimens of three species collected in both microhabitats were smaller in pneumatophores than in stilt-roots and also differed in b-values; however, the relative health condition was higher only in P. fasciata. Conclusion: The intrinsic conditions of stilt-roots and pneumatophores influence the average size and allometry of fishes at this site. The relative condition does not vary between microhabitats for most species, but may reflect development strategies associated with the environment.
      PubDate: 2022-09-06
      DOI: 10.22458/urj.v14i2.3960
      Issue No: Vol. 14, No. 2 (2022)
       
  • Bioacoustics characterization and habitat use of glass frogs in El
           Salvador

    • Authors: Francisco Samuel Álvarez Calderón, Vladlen Henríquez, Xochilt Pocasangre-Orellana, José Guadalupe Argueta Rivera, Erwin Arquímides Chica Argueta
      Abstract: Introduction: Glass frogs occur from Mexico to South America, and, their taxonomy and distribution are currently debated. In El Salvador, the only species is thought to be Hyalinobatrachium fleischmanni, but it may instead be Hyalinobatrachium viridissimum. In any case, the species is scarcely recorded and understudied. Objective: To estimate the species distribution in the Río Lempa basin, and to compare its call with available records. Methods: We used local volunteers to sample 53 sites in Cabañas and Morazán, El Salvador, during the rainy season (September to November); these were visited once in 2019 and once in 2020. Volunteers counted individuals along transects from 6 to 8 pm and recorded some calls with cell phones. Results: We counted 361 individuals, added 53 new localities (mainly deciduous broad-leaved forest and agricultural systems). Abundance was more related with elevation and forest cover, than with river characteristics. Our evaluation of 32 calls found differences in the peak frequency between these glass frog populations and those of H. fleischmanni and H. viridissimum comb. nov. Conclusion: Salvadorian glass frogs are more widespread than previously recorded, their distribution is more related with elevation and forest than with rivers types, and their taxonomic status remains unsolved.
      PubDate: 2022-09-06
      DOI: 10.22458/urj.v14i2.4008
      Issue No: Vol. 14, No. 2 (2022)
       
  • Avian diversity of a mixed ecosystem matrix altered by cattle raising and
           aquaculture in a coastal zone of Cañas, Costa Rica

    • Authors: Esmeralda Arévalo Huezo, Silvio Boyat, Hilary Calderón Marín, Valeria Castillo Gamboa , Dayana Pérez Zúñiga, Steve Stephens Cárdenas
      Abstract: Introduction: Fragmentation due to the change in land use because of anthropogenic pressures has caused loss of habitats for many bird species, causing from population mobilizations to local extinctions. Níspero in Cañas, is a coastal community in Costa Rica, which presents a mixed landscape, made up of mangrove patches and tropical dry forest, highly vulnerable due to aquaculture, industrialization, and the increase in the cattle frontier. One of the proposed strategies for the conservation of these ecosystems is the sustainable use of natural resources. However, there is still profound lack of knowledge about the bird communities present in these heterogeneous ecological matrices Objective: to characterize the diversity of birdlife in a fragmented landscape. Methods: From July 2018 to January 2019, bird counts were carried out. The sampling sites were classified into four categories: mangrove, pasture, shrimp farms and deciduous forest. General alpha richness, abundance, and diversity were determined for each site. Results: A total 1109 individuals distributed in 42 families, 97 genera and 125 species were registered. The most representative families were Ardeidae and Tyrannidae. Shrimp farms had the highest richness indexes, followed by mangrove and pasture areas. In terms of diversity, no significant differences were found. Conclusion: This first approach demonstrates the importance of efforts to integrate disturbed landscapes into conservation programs, given that they present new ecological configurations that can be exploited by various bird species.
      PubDate: 2022-09-06
      DOI: 10.22458/urj.v14i2.3968
      Issue No: Vol. 14, No. 2 (2022)
       
  • Identification keys for the fish of continental and insular waters of
           Costa Rica. Part II: Cichliformes, Cichlidae (Mojarras, Guapotes, Tilapias
           and allies)

    • Authors: Arturo Angulo, Jorge San Gil-León
      Abstract: Introduction: Cichlids (Cichlidae, Cichliformes) constitute one of the most diverse families of freshwater fishes on the planet. In Costa Rica about 10% of the total known species belong to this group. Objective: Provide, to those interested (i.e., students, academics, researchers, hobbysts and others), updated information (in a friendly language) that updates the composition, classification and nomenclature, as well as allowing the correct identification, of all species of the Cichlidae occurring in the continental waters of Costa Rica. Methods: A list of species was made considering bibliographic records and information obtained through field work. From this list, an dichotomous key was elaborated, including complementary information on distribution, based mainly on external anatomical characters and coloration patterns. The information used for the elaboration of the key came from three main sources: scientific literature, review of museum specimens and fieldwork. Results: A total of 14 genera and 28 species were listed and analyzed. The resulting key is composed of 27 steps allowing the identification of all species of Cichlidae of Costa Rica. This paper also includes a photographic catalog and updated data on the nomenclature of the species listed. Conclusion: With this contribution, the state of knowledge about the taxonomy, nomenclature, regional and local distribution of the Cichlidae of Costa Rica is updated. The key allows the correct identification of all species of the family and will serve as the basis for future local and regional studies.
      PubDate: 2022-09-06
      DOI: 10.22458/urj.v14i2.4029
      Issue No: Vol. 14, No. 2 (2022)
       
  • Temperature and fruit selection favor seed germinations of the tropical
           tree Myroxylon balsamum (Fabaceae)

    • Authors: Diego Aguilar Sandí, Elmer G. García
      Abstract: Introduction: Myroxylon balsamum is a tree species native to the Neotropics; and its populations may be declining due to logging and habitat loss. Objective: To evaluate the germinative response of seeds under three temperature conditions, and in fruits selected by seed-chamber thickness. Methods: The fruits were collected in the Central Valley of Costa Rica between November 2019 and June 2020. The germinative response was evaluated at 20ºC, 20/30ºC and 30ºC. The thickness of the seed-chambers was measured and dissected. The fruits were classified as filled (thickness ≥ 0,7cm) and as vain (thickness < 0,7cm). Seed germination within fruits was evaluated at 20ºC, 20/30ºC and 30ºC. Results: As the temperature increased, the time for 50% of the seeds to germinate decreased, and the number of seeds germinated per day, increased. However, there was contamination by pathogens, which caused seed death. Filled fruits germinated well at the three temperatures (92% at 20/30ºC; 86% at 30ºC), while in the vain fruits there was germination only at 20/30ºC (4%) and pathogen contamination could be controlled. Conclusion: The germination for this tree is favored at 20/30ºC and at 30ºC, as long as seeds remain inside fruits with subglobose seed-chambers (thickness ≥ 07cm).
      PubDate: 2022-09-06
      DOI: 10.22458/urj.v14i2.4091
      Issue No: Vol. 14, No. 2 (2022)
       
  • Risk assessment for arsenic, in low concentrations, for agricultural
           workers in Cartago, Costa Rica

    • Authors: Eric Morales Mora, Kenia Barrantes Jiménez, Wilson Beita Sandí, Luz Chacón Jiménez
      Abstract: Introduction: Arsenic, an element that can be harmful to human health, is abundant in the environment. It was among the first substances recognized as carcinogenic, and its presence in water is common in Latin America. Its levels in water sources are relevant for decision-making and sanitary control. This study is the first in Latin America with a mathematical model of the risk and burden of disease. Objective: To evaluate the exposure to low levels of arsenic in agricultural workers in a Costa Rican basin with this new technique. Methods: We sampled arsenic in three points along the Purires River, Cartago, between September 2011 and August 2012. We used “censored value” estimates; risk assessment with quadratic exponential models and Monte Carlo simulations to determine the risk of cancer, for agricultural workers, by type and route of exposure during irrigation. Results: Concentrations did not differ by site, but were higher in the dry season. The risk level and burden of disease were not acceptable. Disease burden is a more rigorous indicator than the individual calculation of probability of occurrence. Our estimated risk level is low compared to other studies outside the region, but not comparable to previous work in Latin America, which used a different method. Conclusion: A decade ago, in the Purires basin, arsenic concentrations were higher in the dry season and the risk level and burden of disease were not acceptable.
      PubDate: 2022-09-06
      DOI: 10.22458/urj.v14i2.4070
      Issue No: Vol. 14, No. 2 (2022)
       
 
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