3,222 research outputs found
Scaling-up climate services with users in Latin America
Latin America farmers are highly vulnerable to climate variability, with crop losses observed throughout the region on a virtually annual basis. For instance, as indicated by the United Nations’ Food and Agriculture Organization (FAO) and World Food Program (WFP), the 2014–2017 drought conditions in Central America affected over 3.5 million people in Guatemala, Honduras and El Salvador. At the same time, local stakeholders and farmers generally have limited access to existing climate and forecast information, do not have sufficient capacities to understand the climate information and/or mechanisms to relate this information to the impact that climate variations can generate at a local level. This precludes the translation of information into actionable knowledge, and therefore into action.
In this study, we describe a process through which scientists and strategic partners have co-developed, tested and scaled out an approach to assess, co-produce, translate and transfer climate information to enable agricultural decision making –the Local Technical Agroclimatic Committees (LTAC). LTACs allow open and clear dialogues about climate variations at multiple timescales, how these can affect crops, and the design of measures to reduce crop loss, particularly providing agronomic recommendations to farmers. We systematically describe the process of evidence generation, creation, partner engagement, scaling up, and monitoring of the approach throughout Latin America.
Currently, 35 LTACs exist in 9 Latin American countries, engaging more than 250 public and private institutions, increasing the resilience and food security of an estimated 330,000 farmers, and potentially transforming how Latin American farmers manage climate risk. The study illustrates changes in institutional and farmers' capacities to co-produce, translate and use climate information and explores how better climate and crop prediction models can effectively underpin this process. We show how strategic alliances with farmer organizations, national public, and private and regional climate outlook forums help deliver improved and accurate climate information to users. Finally, we document how LTACs and their integration with other local-scale processes have led to changes in farmers’ management practices to take better advantage of good climatic conditions or avoid losses
Cosecha de Alcances: Valoración de las transformaciones producidas por las Mesas Técnicas Agroclimáticas (MTA) en Latinoamérica
Durante el 2019 se realizó un proceso de análisis de las transformaciones que han generado las Mesas Técnicas Agroclimáticas (MTA), en los territorios en que han sido establecidas durante los últimos 6 años. El estudio se enfoca en los cambios observables de comunidades, organizaciones o instituciones que han modificado sus acciones, relaciones, políticas y prácticas en cuatro países de Latinoamérica. Cinco áreas de transformación han sido identificadas i) mayor confianza en la calidad de información climática y agroclimática en el nivel local; ii) información agroclimática más conocida, comprensible y conectada; iii) democratización de conocimiento climático; iv) transformaciones en las prácticas agrícolas, y v) incidencia política y transformación institucional. Se verifican más de 140 alcances o cambios sobre dichas áreas.
Se evidencia que las MTA analizadas han promovido un mayor acercamiento de las Instituciones Meteorológicas Nacionales a las necesidades de los territorios, lo que, a su vez, ha propiciado la creación de comunidades de práctica locales sobre la aplicación de conocimientos de clima en la toma de decisiones. En efecto, se tiene evidencia que los agricultores adaptan sus prácticas productivas tomando decisiones basadas en información de variabilidad climática local, reduciendo pérdidas y aumentando rentabilidad. Se demuestra, además, que el desarrollo de alianzas inter-institucionales derivadas de las MTA en los países, ayudan a la construcción y fortalecimiento de políticas públicas locales y nacionales para la adaptación al cambio y la variabilidad climática en la agricultura. Finalmente, se identifican diversas oportunidades y desafíos relacionados con liderazgo y la sostenibilidad del proceso de establecimiento de las MTA en Latinoamérica.During 2019 a process of analysis of the effects or transformations that the Local Agro climatic Technical Committees (MTA) have been carried out, in the territories in which they have been established during the last 5 years. The study focuses on the observable changes of individuals, communities, organizations or institutions that have modified their actions, relationships, policies and practices in five Latin American countries. Five areas of transformation have been identified as outcomes of the MTAs, among which are analyzed: i) greater confidence in the quality of climate and agro climatic information at the local level; ii) best-known, understandable and connected agro climatic information; iii) democratization of climate knowledge; iv) transformations in agricultural practices, and v) political influence and institutional transformation. More than 140 scopes or changes over these areas are verified.
There is evidence that the MTAs have promoted a closer approach of the national meteorological institutions to the need of the territories farmers, which in turn has led to the creation of local communities of practice on the application of climate knowledge in decision making agricultural. Indeed, evidence shows that farmers adapt their productive practices by making decisions based on information on local climate variability, reducing losses and increasing profitability. It is also demonstrated that the development of inter-institutional alliances derived from MTAs in the countries, helps to build and strengthen local and national public policies for adaptation to climate change and variability in agriculture. Finally, various opportunities and challenges related to leadership and the sustainability of the MTA establishment process in Latin America are identified
Bounds on charged higgs boson in the 2HDM type III from Tevatron
We consider the Two Higgs Doublet Model (2HDM) of type III which leads to
Flavour Changing Neutral Currents (FCNC) at tree level. In the framework of
this model we can use an appropriate form of the Yukawa Lagrangian that makes
the type II model limit of the general type III couplings apparent. This way is
useful in order to compare with the experimental data which is model dependent.
The analytical expressions of the partial width are
derived and we compare with the data available at this energy range. We examine
the limits on the new parameters from the validness of
perturbation theory.Comment: 14 pages, 4 figures, Universidad Nacional de Colombia. typos
correcte
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Los Alamos National Laboratory`s Mobile Real Time Radiography System
A 450-KeV Mobile Real Time Radiography (RTR) System was delivered to Los Alamos National Laboratory (LANL) in January 1996. It was purchased to inspect containers of radioactive waste produced at (LANL). Since its delivery it has been used to radiograph greater than 600 drums of radioactive waste at various LANL sites. It has the capability of inspecting waste containers of various sizes. It has three independent X-Ray acquisition formats. The primary system used is a 12 in. image intensifier, the second is a 36 in. linear diode array (LDA) and the last is an open system. It is fully self contained with on board generator, HVAC and a fire suppression system. It is on a 53 ft long X 8 ft. wide X 14 ft. high trailer that can be moved over any highway requiring only a easily obtainable overweight permit because it weighs approximately 38 tons. It was built to conform to industry standards for a cabinet system which does not require an exclusion zone. The fact that this unit is mobile has allowed us to operate where the waste is stored, rather than having to move the waste to a fixed facility
Novel use of plga microspheres to create an animal model of glaucoma with progressive neuroretinal degeneration
Progressive degeneration of neuroretinal tissue with maintained elevated intraocular pressure (IOP) to simulate chronic glaucoma was produced by intracameral injections of poly (lactic-co-glycolic) acid (PLGA) microspheres (Ms) in rat eyes. The right eye of 39 rats received different sizes of PLGA-Ms (2 µL suspension; 10% w/v): 14 with 38–20 µm Ms (Ms38/20 model) and 25 with 20–10 µm particles (Ms20/10 model). This novel glaucoma animal model was compared to the episcleral vein sclerosis (EPI) model (25 eyes). Injections were performed at baseline, two, four and six weeks. Clinical signs, IOP, retina and optic nerve thicknesses (using in vivo optical coherence tomography; OCT), and histological studies were performed. An IOP increment was observed in all three groups, however, the values obtained from the PLGA-Ms injection resulted lower with a better preservation of the ocular surface. In fact, the injection of Ms20/10 created a gentler, more progressive, and more sustained increase in IOP. This IOP alteration was correlated with a significant decrease in most OCT parameters and in histological ganglion-cell count for the three conditions throughout the eight-week follow-up. In all cases, progressive degeneration of the retina, retinal ganglion cells and optic nerve, simulating chronic glaucoma, was detected by OCT and corroborated by histological study. Results showed an alternative glaucoma model to the well-known episcleral vein model, which was simpler to perform, more reproducible and easier to monitor in vivo
Influence of chronic ocular hypertension on emmetropia: Refractive, structural and functional study in two rat models
Chronic ocular hypertension (OHT) influences on refraction in youth and causes glaucoma in adulthood. However, the origin of the responsible mechanism is unclear. This study analyzes the effect of mild-moderate chronic OHT on refraction and neuroretina (structure and function) in young-adult Long-Evans rats using optical coherence tomography and electroretinography over 24 weeks. Data from 260 eyes were retrospectively analyzed in two cohorts: an ocular normotension (ONT) cohort (20 mmHg), in which OHT was induced either by sclerosing the episcleral veins (ES group) or by injecting microspheres into the anterior chamber. A trend toward emmetropia was found in both cohorts over time, though it was more pronounced in the OHT cohort (p < 0.001), especially in the ES group (p = 0.001) and males. IOP and refraction were negatively correlated at week 24 (p = 0.010). The OHT cohort showed early thickening in outer retinal sectors (p < 0.050) and the retinal nerve fiber layer, which later thinned. Electroretinography demonstrated early supranormal amplitudes and faster latencies that later declined. Chronic OHT accelerates emmetropia in Long–Evans rat eyes towards slowly progressive myopia, with an initial increase in structure and function that reversed over time. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
WIYN Imaging of the Globular Cluster Systems of the Spiral Galaxies NGC891 and NGC4013
We present results from a WIYN 3.5m telescope imaging study of the globular
cluster (GC) systems of the edge-on spiral galaxies NGC891 and NGC4013. We used
the 10' x 10' Minimosaic Imager to observe the galaxies in BVR filters to
projected radii of ~20 kpc from the galaxy centers. We combined the WIYN data
with archival and published data from WFPC2 and ACS on the Hubble Space
Telescope to assess the contamination level of the WIYN GC candidate sample and
to follow the GC systems further in toward the galaxies' centers. We
constructed radial distributions for the GC systems using both the WIYN and HST
data. The GC systems of NGC891 and NGC4013 extend to 9+/-3 kpc and 14+/-5 kpc,
respectively, before falling off to undetectable levels in our images. We use
the radial distributions to calculate global values for the total number (N_GC)
and specific frequencies (S_N and T) of GCs. NGC4013 has N_GC = 140+/-20, S_N =
1.0+/-0.2 and T = 1.9+/-0.5; our N_GC value is ~40% smaller than a previous
determination from the literature. The HST data were especially useful for
NGC891, because the GC system is concentrated toward the plane of the galaxy
and was only weakly detected in our WIYN images. Although NGC891 is thought to
resemble the Milky Way in its overall properties, it has only half as many GCs,
with N_GC = 70+/-20, S_N = 0.3+/-0.1 and T = 0.6+/-0.3. We also calculate the
galaxy-mass-normalized number of blue (metal-poor) GCs in NGC891 and NGC4013
and find that they fall along a general trend of increasing specific frequency
of blue GCs with increasing galaxy mass. Given currently available resources,
the optimal method for studying the global properties of extragalactic GC
systems is to combine HST data with wide-field, ground-based imaging with good
resolution. The results here demonstrate the advantage gained by using both
methods when possible.Comment: 43 pages, 11 figures 6 tables; accepted to The Astronomical Journal.
Online AJ version at http://iopscience.iop.org/1538-3881/140/2/430
Chronic glaucoma using biodegradable microspheres to induce intraocular pressure elevation. Six-month follow-up
Background: To compare two prolonged animal models of glaucoma over 24 weeks of follow-up. A novel pre-trabecular model of chronic glaucoma was achieved by injection of biodegradable poly lactic-co-glycolic acid (PLGA) microspheres (10–20 µm) (Ms20/10) into the ocular anterior chamber to progressively increase ocular hypertension (OHT). Methods: Rat right eyes were injected to induce OHT: 50% received a suspension of Ms20/10 in the anterior chamber at 0, 2, 4, 8, 12, 16 and 20 weeks, and the other 50% received a sclerosing episcleral vein injection biweekly (EPIm). Ophthalmological clinical signs, intraocular pressure (IOP), neuroretinal functionality measured by electroretinography (ERG), and structural analysis of the retina, retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) protocols using optical coherence tomography (OCT) and histological exams were performed. Results: Both models showed progressive neuroretinal degeneration (p < 0.05), and contralateral eye affectation. The Ms20/10 model showed a more progressive increase in IOP and better preservation of ocular surface. Although no statistical differences were found between models, the EPIm showed a tendency to produce thicker retinal and thinner GCL thicknesses, slower latency and smaller amplitude as measured using ERG, and more aggressive disturbances in retinal histology. In both models, while the GCL showed the greatest percentage loss of thickness, the RNFL showed the greatest and earliest rate of thickness loss. Conclusions: The intracameral model with biodegradable microspheres resulted more like the conditions observed in humans. It was obtained by a less-aggressive mechanism, which allows for adequate study of the pathology over longer periods. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Thermal, dielectrical and mechanical response of α and β-poly(vinilydene fluoride)/Co-MgO nanocomposites
Nanocomposites of the self-forming core-shell Co-MgO nanoparticles, which were of approximately 100 nm in diameter, and poly(vinylidene fluoride) (PVDF) polymer have been prepared. When the polymer is crystallized in the α-phase, the introduction of the nanoparticles leads to nucleation of the γ-phase of PVDF, increasing also the melting temperature of the polymer. With the introduction of the Co-MgO particles, the dielectric constant of the material slightly increases and the storage modulus decreases with respect to the values obtained for the pure polymer
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