Instituto Venezolano De Investigaciones Research Articles

First ESR dating of quaternary sediments in Mérida Andes, Western Venezuela

The main objective of this study is to demonstrate that Electron Spin Resonance (ESR) dating of Quaternary sediments can be performed at Venezuelan Laboratory (Laboratorio de Física de la Materia Condensada – Instituto Venezolano de Investigaciones Científicas). The dating was carried out using quartz samples extracted from sedimentary Quaternary fill of three alluvial terraces (Qt12, Qt9 and Qt7) located along the Santo Domingo River (Mérida Andes, Western Venezuela), that have been previously studied and dated by Terrestrial Cosmogenic Isotope (10Be). The sedimentological characteristics of the Qt9 terrace fill indicate that the transport and sedimentation process of the sediments was under stable and high energy conditions. Our ESR dating suggest a maximum age of 85 ± 16 ka for this terrace, which is consistent with the 10Be ages previously published. In the case of the Qt12 and Qt7 terraces, field observations suggest a sediment transport process by debris flows, with rapid deposition. In this case, our ESR ages (228 ± 93 ka, 108 ± 33 ka, for Qt12 and Qt7, respectively) seem to be overestimated compared with the 10Be ages reported in previous studies. These results confirm that the sedimentary material to be used for dating through this technique must be deposited under stable conditions involving long-term sediment transport processes. This will allow the “optical bleaching” of paramagnetic centers to occur before the material is buried, as seems to have happened with the Qt9 terrace sample. The results discussed in this work support the existence of the technological and human resources necessary to carry out numerical dating of Quaternary sediments in Venezuela.

Architecture and operation of a neuronal circuit that modulates pain

The present article is a narrative review that describes the functional characteristics of the neurons that constitute a system whose task is to facilitate or diminish the defensive reflexes and the sensation of pain elicited by real or potential damage to one of our tissues. These neurons are located in the medulla oblongata and are known as on-cells and off-cells. They have anatomical and functional links with the nociceptive circuits of the spinal cord and the sensory nuclei of cranial nerves and control the nocifensive reflexes as well as the activation of the thalamic neurons that in turn activate the cortical neurons responsible for the sensation of pain. It was shown that the on-cells facilitate nociception when they are activated by excitatory neurotransmitters and that the off-cells inhibit nociception when their activity increases due to the attenuation of the GABAergic synapses that keep them inhibited. The results obtained additionally indicate that on-cells and off-cells are a substrate for the action of endogenous and exogenous substances capable of augmenting or diminishing pain, such as opioids, analgesics like aspirin and metamizol, opioid receptor antagonists like naloxone, cannabinoids, antagonists to synaptic neurotransmitters, etc. Many of the findings described herein were obtained by doctoral students, young researchers or visiting faculty members under the present author’s guidance in the Laboratorio de Neurofisiología of the Instituto Venezolano de Investigaciones Científicas (IVIC) or by the author during a one-year research stay as Visiting Full Professor in the University of California San Francisco.

The northernmost South American fossil record of Boa constrictor (Boidae, Boinae) from the Plio–Pleistocene of El Breal de Orocual (Venezuela)

Onary-Alves, S.Y., Hsiou, A.S. & Rincón, A.D., July 2016. The northernmost South American fossil record of Boa constrictor (Boidae, Boinae) from the Plio–Pleistocene of El Breal de Orocual (Venezuela). Alcheringa 41, xxx–xxx. ISSN 0311-5518.Boa constrictor is an extant boid widely distributed through the neotropical region, from the north of Central America to central Argentina. The fossil record of the species includes examples from several localities across the Americas that extend beyond the current distribution of the species. Here we report the first Plio–Pleistocene fossils of Boa from Monagas state, Venezuela. The material comes from El Breal de Orocual (Maturín municipality), which is an inactive tar seep deposit emplaced within the Mesa Formation. The specimens consist of two isolated anterior trunk vertebrae, an articulated sequence of six mid-trunk vertebrae and two posterior trunk vertebrae. The vertebrae are attributed to B. constrictor based on the following features: robust and high vertebrae; thick zygosphene with a notched or concave anterior edge; presence of a paracotylar, subcentral and lateral foramina; marked parasagittal ridges; epizygapophyseal process evident on the dorsal surface of the postzygapophyseal articular facets and high blade-like neural spine. The presence of B. constrictor in northern of Venezuela indicates a palaeoenvironment probably like savanna crossed by rivers with riparian forests, and suggests the predominance of a mesothermal climate with a moderate rainfall.Silvio Y. Onary-Alves [silvioyuji@gmail.com], Programa de Pós-graduação em Biologia Comparada, Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo (USP), Av. Bandeirantes 3900, CEP 14040901, Ribeirão Preto, São Paulo, Brazil; Annie S. Hsiou [anniehsiou@ffclrp.usp.br], Laboratório de Paleontologia, Faculdade de Filosofia, Ciências e Letras, Departamento de Biologia, Universidade de São Paulo (USP), Av. Bandeirantes 3900, CEP 14040901, Ribeirão Preto, São Paulo, Brazil; Ascanio D. Rincón [paleosur1974@gmail.com], Laboratorio de Paleontología, Centro de Ecología, Instituto Venezolano de Investigaciones Científicas (IVIC), Carretera Panamericana Km 11, 1020-A Caracas, Venezuela.

NOS2A Gene Polymorphism in Susceptibility to Pulmonary Tuberculosis

Event Abstract Back to Event NOS2A Gene Polymorphism in Susceptibility to Pulmonary Tuberculosis Eloisa Lara Gonzalez1, Fernando A. Hernandez1 and Mercedes T. Fernandez Mestre1* 1 Instituto Venezolano de Investigaciones Cientificas, Centro de Medicina Experimental, Venezuela Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis, which primarily affects the lungs causing pulmonary tuberculosis. In the World Health Organization (WHO) Global Tuberculosis Report for 2014 there were 9.0 million new TB cases in 2013 and 1.5 million TB deaths (1.1 million among HIV-negative and 0.4 million among HIV-positive) of which 218,875 new cases and relapses occurred in the Americas. In Venezuela, according to the WHO, the incidence of new and relapse TB cases is among 20-49 per 100,000 inhabitants. The first interaction between Mycobacterium tuberculosis and the host occurs in pulmonary alveoli, where bacillus is phagocytosed by dendritic cells and macrophages. Nitric oxide (NO) plays a major role in the host-defense mechanism in response to infections and is implicated in bacteriostatic as well as bactericidal processes. NO is produced by three enzyme nitric oxide synthase (NOS) different: NOS1, NOS2 and NOS3. In the promoter region of the gene NOS2 has been identified polymorphisms that affect the binding of transcription factors affecting the concentrations of NO. Since that genetic polymorphism in the promoter of the NOS2 gene could modulate production of NO we investigated in this study the potential association between the NOS2G-954C polymorphism and the development of tuberculosis. Sixty nine patients with pulmonary TB and 94 apparently healthy individuals who have been exposed to Mycobacterium tuberculosis were genotyped for the NOS2G-954C polymorphism by PCR-RFLP. Our results showed not significant association between -954G/C NOS2A variant and susceptibility to either infection or the development of tuberculosis. Furthermore, we found no correlation between different genotypes -954G/C and the concentration of nitrite in plasma. However, we observed in the group of controls with tuberculin skin test positive (TST+) high concentrations of nitrite. In conclusion, the production of nitric oxide would control the Mycobacterium tuberculosis and the presence of other variants of NOS2A gene could determine its concentrations. Acknowledgements The authors are grateful to the persons that participated in this study. This study was supported by CRP - ICGEB Research Grant- CRP/VEN11-01 References Burgner, D. Rockett, K., Kwiatkowski, D. 1999. Nitric oxide and infectious diseases. Dis Childhood 81: 185-188. Kun, J. F., Mordmϋller, B., Perkins, D. J., May, J., Mercereau-Puijalon, O., Alpers, M., Weinberg, J. B., Kremsner, P. G. 2001. Nitric Oxide Synthase 2Lambaréné (G-954C), Increased Nitric Oxide Production, and Protection against Malaria. J. Infect. Dis. 184: 330-336. World Health Organization. Global Tuberculosis Report. 2014. Disponible en: http://www.who.int/tb/publications/global_report/en/ Yang, CH., Yuk, JM. y Jo, EK. 2009. The Role of Nitric Oxide in Mycobacterial Infections. Immun. Netwk. 9: 46-52. Keywords: Polymorphism, Genetic, Tuberculosis, Pulmonary, Nitric Oxide, Nitric Oxide Synthase, TST Conference: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología, Medellin, Colombia, 13 Oct - 16 Oct, 2015. Presentation Type: Poster Presentation Topic: Immunogenetics Citation: Lara Gonzalez E, Hernandez FA and Fernandez Mestre MT (2015). NOS2A Gene Polymorphism in Susceptibility to Pulmonary Tuberculosis. Front. Immunol. Conference Abstract: IMMUNOCOLOMBIA2015 - 11th Congress of the Latin American Association of Immunology - 10o. Congreso de la Asociación Colombiana de Alergia, Asma e Inmunología. doi: 10.3389/conf.fimmu.2015.05.00110 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 06 Apr 2015; Published Online: 14 Sep 2015. * Correspondence: Dr. Mercedes T Fernandez Mestre, Instituto Venezolano de Investigaciones Cientificas, Centro de Medicina Experimental, Caracas, Distrito Capital, 21827, Caracas 1020A, Venezuela, mfernandezmestre@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Eloisa Lara Gonzalez Fernando A Hernandez Mercedes T Fernandez Mestre Google Eloisa Lara Gonzalez Fernando A Hernandez Mercedes T Fernandez Mestre Google Scholar Eloisa Lara Gonzalez Fernando A Hernandez Mercedes T Fernandez Mestre PubMed Eloisa Lara Gonzalez Fernando A Hernandez Mercedes T Fernandez Mestre Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Special issue: III Congress of Theoretical and Computational Physical Chemistry, 2–4 of December of 2010, Altos de Pipe, Caracas, Venezuela

This special issue of the Journal of Computational Methods in Science and Engineering (JCMSE) consists of a selection of papers about the presentations in the III Congress of Theoretical Physical and Computational Chemistry III-CFQTC, held at Altos de Pipe, Caracas, in the Instituto Venezolano de Investigaciones Cientificas IVIC, from 02 to 04 December 2010. The articles were written by the most important Venezuelan scientists in areas of molecular modeling, theoretical chemistry, computational catalysis, bioinformatic and medicinal chemistry, calculations of reaction mechanisms and kinetics, prediction of molecular electric and magnetic properties and chemical process simulation in the industry, as stated in the II CFQTC held at Choroni, 2008. Invited researchers attended to the III-CFQTC with 8 plenary lectures of high scientific quality and more than 80 posters distributed in two sessions were also presented. The attendance was circa 100 participants from different universities and research institutes. Participants were invited to submit manuscripts of their presentation for a JCMSE special issue, from which 19 of them were accepted after a careful peer review process. We wish to thanks the speakers for their lucid and interesting conferences. Also, we greatly appreciate all the persons and institutions allowing III CFQTC to be held in Venezuela: IVIC, Intevep-PDVSA, Universidad Nacional de Colombia, Academia Venezolana de Ciencias Fisicas Matematicas y Naturales, Universidad Central de Venezuela (UCV), Universidad de Los Andes (LUZ), Universidad Simon Bolivar (USB) and also private enterprises as Fundacion Empresas Polar. They kindly contributed to the costs of travelling and lodging of some of the invited speakers. The offer of JCMSE to publish extended evaluated manuscripts has been also a very important support for the success of the III-CFQTC. Invited Speakers: Javier Fernandez Sanz, Departamento de Fisico-Quimica, Universidad de Sevilla, Espana.

National Red Lists: the largest global market for IUCN Red List Categories and Criteria

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 6:193-198 (2008) - DOI: https://doi.org/10.3354/esr00129 National Red Lists: the largest global market for IUCN Red List Categories and Criteria Jon Paul Rodríguez1,2,* 1Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Apdo. 20632, Caracas 1020-A,Venezuela 2Provita, Apdo. 47552, Caracas 1041-A, Venezuela *Email: jonpaul@ivic.ve ABSTRACT: The 2 major challenges currently confronting the International Union for Conservation of Nature (IUCN) with regard to the ‘red listing’ process are the taxonomic, and the geographic growth of the data base. Taxonomic growth refers to the objective of gradually assessing the risk of extinction of all the world’s species and periodically repeating such assessments. Geographic growth refers to the increasing number of people around the world interested in performing extinction risk assessments for various groups of organisms in their region or country. The taxonomic challenge, although a large and demanding task, can be addressed by expanding and strengthening the networks of experts organized within the IUCN Species Survival Commission (SSC), which represents a significant scaling-up of a well-developed, known model. However, no current structure within the IUCN has the mandate to address the geographic challenge; this requires the creation of new structures or mechanisms. At least 5 key activities must be implemented to effectively integrate the diffuse network of national assessors into the global red listing process: (1) large-scale publicizing of the Guidelines for Application of IUCN Red List Criteria at Regional Levels, and encouraging the work of national assessors; (2) establishing the IUCN Species Programme as the primary trainer and certifier of multipliers; (3) delegating the majority of training to national institutions; (4) creating a virtual data clearing house for national red lists, seamlessly linked to the global list; and (5) consolidating the IUCN Species Programme as the primary endorser of national red list assessments. Hundreds of regional and national red lists will probably be produced in the next decade using the IUCN Red List Categories and Criteria, particularly because they are now recognized by international agreements such as the 2010 biodiversity target of the Convention on Biological Diversity and the United Nation’s General Assembly Millennium Development Goals. By catalyzing this process, the IUCN would expand the information on the world’s threatened species, while strengthening local scientific capacity for generating and using these data to support conservation action. KEY WORDS: Assessment of extinction risk · Conservation priorities · IUCN Red List · National red lists · Threatened species Full text in pdf format PreviousCite this article as: Rodríguez JP (2008) National Red Lists: the largest global market for IUCN Red List Categories and Criteria. Endang Species Res 6:193-198. https://doi.org/10.3354/esr00129 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 6, No. 2. Online publication date: December 30, 2008 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2008 Inter-Research.

First Report of Tomato yellow leaf curl virus in Venezuela.

Tomato yellow leaf curl virus (TYLCV), a member of the family Geminiviridae, is a serious production constraint to tomato worldwide. In the new world, the virus had been identified as the causal agent of tomato yellow leaf curl disease in the Caribbean countries of the Dominican Republic, Cuba, and Guadeloupe and also in Florida and the Yucatan Peninsula (1). Molecular data from these TYLCV isolates identified the virus as the TYLCV prototype from Israel. During April 2004, tomato plants showing symptoms such as chlorotic leaf edges, upward leaf cupping, leaf mottling, and reduced leaf size indicative of TYLCV were observed in commercial fields in Zulia state, Venezuela. Whiteflies (Bemisia tabaci Gennadius) were present in the field and appeared to be associated with the disease. Leaf samples from nine symptomatic plants were collected and brought to the lab at Instituto Venezolano de Investigaciones Científicas (IVIC) for further analyses. Geminivirus infection of samples was confirmed by PCR amplification with the degenerate primer pair PAL1v1978 and PAR1c494 (2). TYLCV coat protein gene-specific primers KL04-06_TYLCV CP F and KL04-07_TYLCV CP R (3) were used to confirm the diagnosis. These primers amplified the expected 842-bp PCR product from the nine symptomatic samples. One of the resulting amplicons was cloned into the pCR-TOPO vector (Invitrogen, Carlsbad, CA) and sequenced (GenBank Accession No. DQ302033). Sequence comparison with those available in the NCBI database indicated that the sequenced portion of the genome shared 99% nucleotide identity with the TYLCV mild strain from Portugal (GenBank Accession No. AF105975) and 98% nucleotide identity with the TYLCV mild strain from Spain (GenBank Accession No. AF071228), TYLCV Israel isolate (GenBank Accession No. AM234066), and TYLCV Mexico isolate (GenBank Accession No. DQ631892). To our knowledge, this is the first report of TYLCV infecting tomato crops in South America. Further studies are needed to clarify how TYLCV has been introduced into Venezuela.

Crosstalk between Murine Liver Sinusoidal Endothelial Cells (LSEC) and Hematopoietic Stem Cells during In Vitro Hematopoiesis.

Crosstalk between murine liver sinusoidal endothelial cells (LSEC) and hematopoietic stem cells during in vitro hematopoiesis. G. Luna, J. E. Cardier. Laboratorio de Patologia Celular y Molecular, Centro de Medicina Experimental, Instituto Venezolano de Investigaciones Científicas (IVIC). Apartado 21827, Caracas, VenezuelaWe have showed that at the liver there is a specific hematopoietic microenvironment, constituted by the liver sinusoid endothelial cells (LSEC), which are capable to support, in vitro and in vivo, not only the proliferation but also the differentiation and survival of hematopoietic stem cells (HSC). The ability of LSEC to support hematopoiesis could be related to specific hematopoietic molecules expressed by these cells. In this study, we investigate the expression of some cell adhesion molecules (VCAM-1, ICAM-1, and the integrin a4b1 ), and early acting hematopoietic cytokines (IL-6 and GM-CSF), on LSEC cocultured with HSC. The expression of VCAM-1, ICAM-1, α4β1, IL6 and GM-SCF was increased on LSEC cocultured with HSC. In contrast, a significant decrease in the expression of IL-6 and GM-CSF in the HSC derived from the same cocultures was observed. The blockade of VCAM-1 on LSEC reduced significantly the adhesion of HSC to LSEC monolayers, suggesting that this molecule is involved in the binding of HSC to LSEC microenvironments. There were not changes in the expression of the molecules evaluated when the LSEC and HSC were co-cultured in non-contact conditions, suggesting that soluble factors do not participate in regulating the expression of these molecules. Our data shows that during in vitro hematopoiesis, LSEC are activated to express molecules associated with the hematopoiesis process. LSEC activation is regulated by the contact between these cells and HSC. By expressing critical hematopoietic microenvironment molecules, LSEC may regulate the proliferation and differentiation of HSC, during liver extramedullary hematopoiesis.

Errata

The Journal of PhysiologyVolume 564, Issue 3 p. 953-953 Free Access Errata This article corrects the following: Two developmental switches in GABAergic signalling: the K+–Cl− cotransporter KCC2 and carbonic anhydrase CAVII Claudio Rivera, Juha Voipio, Kai Kaila, Volume 562Issue 1The Journal of Physiology pages: 27-36 First Published online: December 22, 2004 Calcium transients in developing mouse skeletal muscle fibres Joana Capote, Pura Bolaños, Ralph Peter Schuhmeier, Werner Melzer, Carlo Caputo, Volume 564Issue 2The Journal of Physiology pages: 451-464 First Published online: April 6, 2005 Excitatory purinergic neurotransmission in smooth muscle of guniea-pig taenia caeci Yong Zhang, William G. Paterson, Volume 563Issue 3The Journal of Physiology pages: 855-865 First Published online: March 8, 2005 First published: 21 April 2005 https://doi.org/10.1113/jphysiol.2005.564001Citations: 1AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat The authors of Rivera et al. (2005) would like to publish the following clarification: in our review, we emphasized the fact that using Cs+ as an internal cation in whole-cell recordings results in a profound dysfunction of the neuronal K+–Cl− cotransporter, KCC2. This is because Cs+ is a very poor substrate of this ion transporter, with a maximum transport rate (Vmax) for Cs+ that is < 20% of the value for K+ (Williams & Payne, 2004). On page 29, we stated that ‘Unfortunately, the kinetic data in the only published model of neuronal K+–Cl− cotransport in neurones (Staley & Proctor, 1999) were obtained using Cs+ in whole-cell experiments – and hence, in the absence of functional KCC2!’ Since the publication of our review, it has been brought to our attention that both K+ and Cs+ were used by the authors, with essentially similar results. This is true and, if anything, it strengthens our concerns about the validity of the above modelling study which yielded a value of Vmax for Cs+ that is higher than for K+ (about 7 mmol l−1 s−1 for Cs+ and about 5–6 mmol l−1 s−1 for K+). The authors of Zhang & Paterson, (2005) would like to correct an error on page 858. In line 7 of the first paragraph, a value of 361 ± 83 ms is given for the control. This value should have read 661 ± 83 ms. In addition, in the title ‘guniea-pig’ should be ‘guinea-pig’. The authors of Capote et al. (2005) would like to correct the affiliation of Carlo Caputo; the affiliation should be the Instituto Venezolano de Investigaciones Cientificas IVIC. References Capote J, Bolanos P, Schuhmeier RP, Melzer W & Caputo C (2005). Calcium transients in developing mouse skeletal muscle fibres. J Physiol 564, 451– 464. Rivera C, Voipio J & Kaila K (2005). Two developmental switches in GABAergic signalling: the K+–Cl− cotransporter KCC2 and carbonic anhydrase CAVII. J Physiol 562, 27– 36.DOI: 10.1113/jphysiol.2004.077495 Staley KJ & Proctor WR (1999). Modulation of mammalian dendritic GABAA receptor function by the kinetics of Cl− and HCO3− transport. J Physiol 519, 693– 712.DOI: 10.1111/j.1469-7793.1999.0693n.x Williams JR & Payne JA (2004). Cation transport by the neuronal K+–Cl− cotransporter KCC2: thermodynamics and kinetics of alternate transport modes. Am J Physiol Cell Physiol 287, C919– C931. Zhang Y & Paterson W (2005). Excitatory purinergic neurotransmission in smooth muscle of guniea-pig taenia caeci. J Physiol 563, 855– 865.DOI: 10.1113/jphysiol.2004.077636 Citing Literature Volume564, Issue3May 2005Pages 953-953 ReferencesRelatedInformation

A Catalogue of the Type Material in the IVIC Reference Collection of Decapoda, Venezuela

A catalogue of the type specimens deposited in the reference collection of decapod crustaceans built up by the late Gilberto Rodríguez and collaborators, from 1960 to 2004, at the Instituto Venezolano de Investigaciones Científicas (IVIC), Venezuela, is presented. It contains the field data and taxonomic information for 32 holotypes and 25 paratypes of 42 species and subspecies belonging to three families (2 Palaemonidae, 3 Trichodactylidae, and 37 Pseudothelphusidae).

MASS PROPAGATION OF ECHINACEA ANGUSTIFOLIA: A PROTOCOL REFINEMENT USING SHOOT ENCAPSULATION AND TEMPORARY IMMERSION LIQUID SYSTEM

ISHS XXVI International Horticultural Congress: The Future for Medicinal and Aromatic Plants MASS PROPAGATION OF ECHINACEA ANGUSTIFOLIA: A PROTOCOL REFINEMENT USING SHOOT ENCAPSULATION AND TEMPORARY IMMERSION LIQUID SYSTEM

Short- and long-term monitoring of radon, thoron and carbon dioxide in soil-gas at Altos de pipe, Venezuela

We have measured radon and thoron activities in soil-gases since July 9, 1997 Cariaco earthquake (Mw=6.9) until the end of 2000. Carbon dioxide concentrations were also monitored between 1998–2000. The soil-gas was collected between 50–55 cm depths at two sampling points at Altos de pipe (Instituto Venezolano de Investigaciones Cientificas-IVIC) near Caracas, Venezuela. The radon and thoron measurements were performed daily employing radiation monitors with scintillation cells and the carbon dioxide was monitored with portable gas analyzers. Average weekly and monthly values were calculated and plotted for this three-four year period. In general, both the radon and carbon dioxide values showed sinusoidal trends due to seasonal changes. During the dry season the radon and carbon dioxide values decreased, while the radon activity was relative constant (flat) during the rainy season at one of the sampling points. Only two monthly radon values were seen to be anomalous in the graphs in respect to seven anomalous periods for the average weekly values. No anomalous periods were clearly seen for carbon dioxide. Finally, it was difficult to try to relate these radon anomalous periods with specific earthquakes due to the large number of minor earthquakes during these years, but it seem that the minor earthquake (Mb=5.9) of October 4, 2000 could be associated with the radon anomalous period in September, when there were no other minor earthquakes (Mb≥4.0).

Preface

Journal of Physical Organic ChemistryVolume 15, Issue 12 p. 789-789 Preface Preface† Gabriel Chuchani, Gabriel Chuchani Instituto Venezolano de Investigaciones Científicas Caracas, VenezuelaSearch for more papers by this authorEduardo Humeres, Eduardo Humeres Universidade Federal de Santa Catarina Florianópolis, SC, BrazilSearch for more papers by this author Gabriel Chuchani, Gabriel Chuchani Instituto Venezolano de Investigaciones Científicas Caracas, VenezuelaSearch for more papers by this authorEduardo Humeres, Eduardo Humeres Universidade Federal de Santa Catarina Florianópolis, SC, BrazilSearch for more papers by this author First published: 21 November 2002 https://doi.org/10.1002/poc.580 † Presented in part at the Sixth Latin American Conference on Physical Organic Chemistry (CLAFQO-6), held at Isla Margarita, Venezuela, during December 2001. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume15, Issue12Special Issue: CLAFQO Special IssueDecember 2002Pages 789-789 RelatedInformation

Overview of some biomedical research projects in tropical medicine conducted at the Instituto Venezolano de Investigaciones Cientificas.

The Instituto Venezolano de Investigaciones Cientificas (IVIC) is a government-funded multidisciplinary academic institution dedicated to research, development and technology in many areas of knowledge. Biomedical projects and publications comprise about 40% of the total at IVIC. In this article, we present an overview of some selected research and development projects conducted at IVIC which we believe contain new and important aspects related to malaria, ancylostomiasis, dengue fever, leishmaniasis and tuberculosis. Other projects considered of interest in the general area of tropical medicine are briefly described. This article was prepared as a small contribution to honor and commemorate the centenary of the Instituto Oswaldo Cruz.

Self-excited soliton motion.

Centro de Fi ´sica, Instituto Venezolano de Investigaciones Cientificas, Apartado 21827, Caracas 1020 A, Venezuela~Received 14 December 1994; revised manuscript received 13 February 1996!We present an extensive analytical and numerical study of the dynamics of kink solitons in Klein-Gordonsystems with nonlinear damping. Particularly, the nonlinear damping could model the interaction of the soli-tons with an active medium. We analyze the existence and stability conditions of stationary states for thesoliton. We present a different kind of bifurcation: a structure-breaking bifurcation. After this bifurcation thesoliton enters a highly nonstationary state ~solitonic explosion!. We show the existence of self-sustainedoscillations of solitons ~solitonic limit cycles!. Finally, we present chaotic motion of solitons similar to theDuffing–Van der Pol type.@S1063-651X~96!05707-8#PACS number~s!: 05.45.1b, 52.35.Sb, 52.35.Mw, 02.30.JrI. INTRODUCTION

The preliminary results of the measurements of environmental levels of 40K and 137Cs in Venezuela

The study of the beta-particle radioactivity in air and 90Sr in rainwater collected at Instituto Venezolano de Investigaciones Cientificas, IVIC, that began in 1959 in conjunction with the U.S. Atomic Energy Commission was discontinued in 1963. But after the Chernobyl nuclear power plant accident in the USSR, work on the radioactive contamination in Venezuela has been renewed. Initially the measurement of 134Cs and 137Cs in imported foodstuffs, such as milk powders and meats were undertaken, and these have now been extended to measurements of environmental levels of 40K and 137Cs in soils, sea sediments and foodstuffs. The data present herein are the only readily available data on radioactive contamination in the environment in Venezuela since 1963. The measurements were performed with a simple Nal(Tl) detector and two single channel analyzers as well as with a 25% efficient hyper-pure germanium semiconductor coupled to a multichannel analyzer system. Finally, these results can be used as baseline values (environmental background) in case of a nuclear accident in the region, as well as to screen imported foodstuff which is suspected to be contaminated.

Non-DR3/DR4 haplotypes in IDDM patients of mixed ethnic origin: [formula omitted], B Esparza, A Calvo, P Gunczler, R Lanes, E Garcia Z Stoikow, O Blabás. Instituto Venezolano de Investigaciones Científicas & Hospital de Clínicas Caracas, CARACAS VENEZUELA

Non-DR3/DR4 haplotypes in IDDM patients of mixed ethnic origin: [formula omitted], B Esparza, A Calvo, P Gunczler, R Lanes, E Garcia Z Stoikow, O Blabás. Instituto Venezolano de Investigaciones Científicas & Hospital de Clínicas Caracas, CARACAS VENEZUELA

IVIC syndrome: report of a second family.

The IVIC syndrome derives its name from the Instituto Venezolano de Investigaciones Cientìficas, where it was described by Arias et al. [Am J Med Genet 6:25-59, 1980]. We report on several individuals in a family with the IVIC syndrome, the second described in the literature. In this family there are 3 affected individuals in 2 generations. This observation shows that the IVIC syndrome is not a private syndrome, and confirms that it is due to an autosomal dominant mutation.

Identification of maize mosaic virus by immunoelectron microscopy

Maize mosaic virus (MMV) causes a severe disease of Zea mays in many tropical and subtropical regions of the world, including the southern U.S. (1-3). Fig. 1 shows internal cross striations of helical nucleoprotein and bounding membrane with surface projections typical of many plant rhabdovirus particles including MMV (3). Immunoelectron microscopy (IEM) was investigated as a method for identifying MMV. Antiserum to MMV was supplied by Ramon Lastra (Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela).

The effect of energy conservation surface overlap breakdown on the low‐temperature ultrasonic attenuation in dielectrics

physica status solidi (b)Volume 133, Issue 2 p. K81-K85 Short Note The effect of energy conservation surface overlap breakdown on the low-temperature ultrasonic attenuation in dielectrics R. Nava, R. Nava Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Física, Caracas Search for more papers by this author R. Nava, R. Nava Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Física, Caracas Search for more papers by this author First published: 1 February 1986 https://doi.org/10.1002/pssb.2221330242Citations: 1 Apartado 1827, Caracas 1010A, Venezuela. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume133, Issue21 February 1986Pages K81-K85 RelatedInformation