2,726 research outputs found
Current perspectives on forest recovery trends in Guanacaste, Costa Rica
Artículo. Instituto Tecnológico de Costa Rica. Escuela de Ingeniería Forestal, Ministerio del Ambiente, Energía y Minas. Sistema Nacional de Áreas de Conservación, 2019The main goal of this study was to evaluate whether the trends in the recovery of forest cover in Guanacaste continued during the past decade
and to evaluate if the socioeconomic drivers of recovery have been altered. Our analysis found that forest cover in Guanacaste province
increased marginally from 48.14% in 2005 to 50.74% in 2012. This implies that the forest recovery process during this period has continued
but with a much smaller pace, showing signs of stagnation. The province landscape has changed since the 1970s, when it was dominated
by livestock ranching and was the most deforested province with only 23.6% of forest cover. Today Guanacaste is a good example of an
economic development forest transition region, with a matrix of land use that is dominated by new forests in different successional stages, which
has resulted in great benefits to society given the ecosystem services that this landscape provides
Host-parasite relationships in root-knot disease of white mulberry
Severe infections of white mulberry feeder roots and heavy soil infestations by Meloidogyne arenaria race 2 were found in southern Spain. This is the first record of M. arenaria on white mulberry in Europe. Morphometric observations, analysis of the esterase electrophoretic pattern, and artificial inoculations of race differentials were used to characterize nematodes. Nematode-induced mature galls were spherical and usually contained one or more females, males, and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. Giant cell cytoplasm
was aggregated along a thickened cell wall. Vascular tissues within galls appeared disorganized. The relationship between the initial nematode population density (Pi) in a series from 0 to 1,024 eggs and juveniles/cm3 soil and growth of white mulberry seedlings was tested in the greenhouse. A Seinhorst model was fitted to plant height and top fresh weight. Tolerance limits of white mulberry to M. arenaria race 2 for plant height and top fresh weight were, respectively, 1.1 and 1.38 eggs and juveniles/cm3 soil. The minimum relative values for plant height and top fresh weight were 0 at Pi > 64 and Pi > 128 eggs and juveniles/cm3 soil, respectively. Maximum
nematode reproduction rate was 435-fold at the lowest Pi.
Additional keywords: histopathology, Morus alba, pathogenicity, threshold limitPeer reviewe
An approach to the natural and engineered nanoparticles analysis in the environment by inductively coupled plasma mass spectrometry
Different approaches to the most relevant and recent studies and applications of inductively coupled plasma mass spectrometry (ICP-MS) applied to the analysis of natural and engineered nanoparticles in the environment are described. Usually several separation methods like polyacrylamide gel electrophoresis (PAGE), field-flow fractionation (FFF) and size exclusion chromatography (SEC) are used prior to the mass spectrometric measurements. In many cases the use of these hyphenated techniques provides important methodologies to know the bioavailability, mobility and toxicity of elements in life and environmental sciences. Alternatively, the capabilities of the single particle detection by ICP-MS (SD-ICP-MS) for the selective identification, characterization and determination of engineered nanoparticles will be also discussed
Mexico’s Tradition and Culture Entering the Digital Age: The Mexican Cultural Heritage Repository Project
Mexico is a country with a vast and extraordinary cultural heritage, which is the result of
a rich history of cultural exchange, syncretism and transculturation. This rich culture has been
materialized through the consolidation of a long and prestigious museum tradition, which at
the same time is sadly characterized by an endemic lack of technological resources rather than
professional skills. As a result, we have found that Mexican museums produce very heterogeneous
forms of documentation, which are often not even managed using information technologies.
Furthermore, most museums deploy ad hoc solutions that directly limit the usefulness and value of
the documentation process itself. In response, the recently founded Mexican Ministry of Culture is
undertaking the development of the Mexican cultural heritage data model (Modelo de Datos México),
which is aimed at contributing to the cultural heritage domain of our country through the correct
characterization and documentation of its cultural objects. It is the first documented experience
in Mexico of a large-scale data model inspired by CIDOC-CRM, which is complemented by a set
of terminological tools that attempt to capture the singularities and idiosyncrasies of the Mexican
cultural sector. In the present paper, we will describe the motivations and decisions made so far to
optimize the data model to the Mexican reality and the development of the project that will define a
set of local terminologies built on the expertise of linguists, information architects, developers and
especially, museum professionals.This research was funded by the Secretaría de Cultura of Mexico
Physical activity, fitness and adiposity: immigrants versus spanish scholars
El objetivo fue analizar las asociaciones entre los niveles de condición física, patrones de actividad física y adiposidad del alumnado nativo e inmigrante. Se estudiaron 612 niños (8-10 años) de colegios públicos, valorándose mediante pruebas antropométricas, condición física y cuestionario de hábitos de actividad física. Se observó que el alumnado que realizaba mayor actividad física presentaba menor índice de masa corporal y mayor condición física. El alumnado inmigrante presentó menor adiposidad y mayor participación en actividades deportivas. No encontramos diferencias en condición física, salvo en chicas inmigrantes, con mayor fuerza del tren inferior. En conclusión, los inmigrantes del presente estudio parecen poseer un perfil más saludable de condición física, actividad física y adiposidad que los nativos.The objective was to analyse the associations of physical fitness and patterns of physical activity with adiposity in native and foreign. This study was performed with 612 school students (8-10 years). Anthropometric measurements, physical fitness and activity patterns were studied. The results showed that students who practiced more physical activity had lower body mass index and higher levels of fitness. Immigrants had lower adiposity and higher participation in sport activities than native students. No differences between native and foreing students in levels were found, except for immigrant girls, who showed greater lower body strengh than the natives ones. In conclusion, immigrants from this study appear to have a healthier fitness, physical activity and adiposity than natives.Este estudio ha sido financiando por la de la Dirección General de Participación e Innovación Educativa, por la que se aprueban proyectos de investigación e innovación educativa y de elaboración de materiales curriculares de de la Consejería de Educación de Andalucía. RESOLUCIÓN de 14 de julio de 2010 (PIV-038/10), y con una beca del Ministerio de Ciencia e Investigación (JCI-2010-07055)
Evaluation of hydrodynamic chromatography coupled to inductively coupled plasma mass spectrometry for speciation of dissolved and nanoparticulate gold and silver
In this study, hydrodynamic chromatography coupled to inductively coupled plasma mass spectrometry has been evaluated for the simultaneous determination of dissolved and nanoparticulate species of gold and silver. Optimization of mobile phase was carried out with special attention to the column recovery of the different species and the resolution between them. Addition of 0.05 mM penicillamine to the mobile phase allowed the quantitative recovery of ionic gold and gold nanoparticles up to 50 nm, whereas 1 mM penicillamine was necessary for quantitative recovery of ionic silver and silver nanoparticles up to 40 nm. The resolution achieved between ionic gold and 10-nm gold nanoparticles was 0.7, whereas it ranged between 0.31 and 0.93 for ionic silver and 10-nm silver nanoparticles, depending on the composition of mobile phase. Best-case mass concentration detection limits for gold and silver species were 0.05 and 0.75 µg L-1, respectively. The developed methods allowed the simultaneous detection of nanoparticulate and dissolved species of gold and silver in less than 10 min. Size determination and quantification of gold and silver species were carried out in different dietary supplements, showing good agreement with the results obtained by electron microscopy and total and ultrafiltrable contents, respectively. Due to the attainable resolution, the quality of the quantitative results is affected by the relative abundance of nanoparticulate and dissolved species of the element and the size of the nanoparticles if present. Graphical abstract: [Figure not available: see fulltext.
First report of Meloidogyne arenaria parasitizing lettuce in southern Spain
During the 2005-2006 autumn to winter lettuce-growing (Lactuca sativa cv. Iceberg) season, severely stunted and yellowing lettuce plants with disease incidence ranging from 80 to 100% were observed in four commercial, fall-sown fields at Almodóvar del Río (Córdoba Province) in southern Spain. Early symptoms consisted of severely reduced growth of the plants that continued with extensive leaf yellowing and the absence of tight-head formation. Attacks by the disease were estimated to cause near complete loss of the crop yields since the lettuce head produced in affected fields were unmarketable. Observations of affected lettuce plants revealed high parasitism of the root system by a root-knot nematode (Meloidogyne sp.) in the main and feeder roots as well as heavy soil infestations by the nematode. The nematode was identified by the female perineal pattern, esterases phenotype, and a sequence-characterized amplified region polymerase chain reaction (SCAR-PCR) technique. Measurements and morphological observations of 20 second-stage juveniles (J2s) (body length = 463 ± 28 μm, dorsal gland orifice from stylet base = 2.8 ± 0.6 μm, stylet length = 10.4 ± 0.5 μm, tail length = 54.4 ± 0.6 μm; hyaline tail terminus = 9.4 ± 0.6 μm) and 10 adult females (stylet length = 14.5 ± 0.7 μm, dorsal gland orifice from stylet base = 4.7 ± 0.5 μm, and perineal pattern with low and rounded dorsal arch with coarse striae) conformed to the description of Meloidogyne arenaria. On the basis of the characteristics of the perineal pattern, the 2-band esterase phenotype, and the 420-bp SCAR fragment, the causal agent was identified as the peanut root-knot nematode M. arenaria. Nematodes were extracted from soil and root samples by standard procedures and their populations quantified. M. arenaria was detected in nearly all soil and root samples assessed, with nematode population densities ranging from 206 to 1,072 eggs and J2s per 5 g of fresh roots. Different Meloidogyne spp. have been reported parasitizing lettuce roots, especially M. hapla in northern areas (2); however, to our knowledge this is the first time that M. arenaria is reported parasitizing lettuce roots in Spain and elsewhere.Peer reviewe
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