Escenarios socioeconómicos futuros para la agricultura y seguridad alimentaria y nutricional en Nicaragua al 2050

En este documento se presentan y analizan doce (12) escenarios socioeconómicos sobre el futuro de la agricultura y la seguridad alimentaria nutricional en el corredor seco de Nicaragua al año 2050. A través de estos escenarios se pretende apoyar la toma decisiones en el país para mejorar la resiliencia del sector frente al cambio climático, buscando promover su uso en la formulación de programas, políticas y proyectos. El abordaje metodológico para la creación de los escenarios presentados tuvo como pilar fundamental la identificación y análisis de los factores contextuales que se estima cambiarán e impactarán el sector agropecuario y la seguridad alimentaria en el corredor seco de Nicaragua hasta el año 2050. Esto se logró mediante un proceso sistemático y participativo a través de entrevistas semi estructuradas con informantes claves del país expertos en el nexo agricultura, SAN y el medio ambiente. De los 17 factores de cambio que se identificaron, se priorizaron los más relevantes e inciertos, cuales formaron la base para la construcción de doce escenarios que exploran el futuro de recursos hídricos, gobernanza y políticas públicas, inestabilidad política, conflictividad social y vulne- rabilidad, practicas productivas, inversión y financiamiento y degradación ambiental. La exploración de escenarios futuros permite conocer las incertidumbres que podrían impactar de manera negativa o positiva la efectividad de las inversiones que se pretenden hacer para fomentar la resiliencia de los productores de la zona del corredor seco de Nicaragua, frente la variabilidad y vulnerabilidad climática. El documento señala aspectos que son relevantes tanto como problemáticos para el futuro de la agricultura y la seguridad alimentaria de este territorio, como también posibles soluciones para aprovechar las oportunidades identificadas y prepararse para los retos que plantean los distintos escenarios considerados

Benthic trophic interactions in an Antarctic shallow water ecosystem affected by recent glacier retreat

The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (d13C and d15N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased connectedness and resource recycling

Study of adsorption process of iron colloid substances on activated carbon by ultrasound

The paper reports on the adsorption of iron colloid substances on activated carbon (PAC) Norit SA UF with using ultrasound. It is found that time of adsorption is equal to three hours. High-frequency electrical oscillation is 35 kHz. The adsorption capacity of activated carbon was determined and it is equal to about 0.25 mg iron colloid substances /mg PAC. The iron colloid substances size ranging from 30 to 360 nm was determined. The zeta potential of iron colloid substances which consists of iron (III) hydroxide, silicon compounds and natura organic substances is about (-38mV). The process of destruction iron colloid substances occurs with subsequent formation of a precipitate in the form of Fe(OH)[3] as a result of the removal of organic substances from the model solution

Review and prospects of the CASCADE data acquisition system at CERN

CASCADE, a multi-processor real-time data-acquisition system for HEP experiments developed at CERN by the ECP-DS group, has now been in operation for one year. The current implementation supports configurations based on VMEbus processors running OS-9 and on UNIX workstations interconnected via VICbus or Ethernet. The project is reviewed by describing the main characteristics of the package, the applications in which it has been used, and the results of this experience. The main improvements of 1994, which include a parameterized multi-level event builder, a remote monitoring option and a powerful run control facility, as well as ongoing developments and prospects for 1995, are presented

Consequences of local gauge symmetry in empirical tight-binding theory

A method for incorporating electromagnetic fields into empirical tight-binding theory is derived from the principle of local gauge symmetry. Gauge invariance is shown to be incompatible with empirical tight-binding theory unless a representation exists in which the coordinate operator is diagonal. The present approach takes this basis as fundamental and uses group theory to construct symmetrized linear combinations of discrete coordinate eigenkets. This produces orthogonal atomic-like "orbitals" that may be used as a tight-binding basis. The coordinate matrix in the latter basis includes intra-atomic matrix elements between different orbitals on the same atom. Lattice gauge theory is then used to define discrete electromagnetic fields and their interaction with electrons. Local gauge symmetry is shown to impose strong restrictions limiting the range of the Hamiltonian in the coordinate basis. The theory is applied to the semiconductors Ge and Si, for which it is shown that a basis of 15 orbitals per atom provides a satisfactory description of the valence bands and the lowest conduction bands. Calculations of the dielectric function demonstrate that this model yields an accurate joint density of states, but underestimates the oscillator strength by about 20% in comparison to a nonlocal empirical pseudopotential calculation.Comment: 23 pages, 7 figures, RevTeX4; submitted to Phys. Rev.

Diamond-Based Thin Film Bulk Acoustic Wave Resonator for Biomedical Applications

Nowadays it is in constant growing the development of thin film bulk acoustic resonators. If the piezoelectric material is going to be implanted in the human body, an important requirement is the biocompatibility of the implant. In this regard, Aluminum Nitride (AlN) has emerged as an attractive alternative for use in biomedical MicroElectroMechanical Systems. Ultrananocrystalline Diamond (UNCD) is a promising material to be used in biomedical applications, due to its extraordinary mulifunctionality; it is exceptional for implantable medical devices requiring stringent biological performance. Since both UNCD and AlN films can be processed via photolithography processes used in microfabrication, the integration of UNCD and AlN films provides the bases for developing a new generation of biocompatible Bio-MEMS/NEMS. Research and development was conducted to produce implantable MEMS devices: Pt/piezoelectric AlN/Pt layer heterostructure was grown and patterned on the UNCD membrane with a Ti adhesion layer. By applying voltages between the top and bottom Pt electrodes layers the piezoelectric AlN layer is energized. The feasibility of the fabrication of biocompatible AlN/diamond-based FBAR structure has been demonstrated.Fil: Zalazar, Martin. Universidad Nacional de Entre Rios. Facultad de Ingenieria. Departamento de Bioingenieria; ArgentinaFil: Guarnieri, Fabio Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico. Centro de Investigación de Métodos Computacionales; Argentina. Universidad Nacional de Entre Rios. Facultad de Ingenieria. Departamento de Bioingenieria; Argentin

Leishmania isoenzyme polymorphisms in Ecuador: Relationships with geographic distribution and clinical presentation

Background: Determinants of the clinical presentation of the leishmaniases are poorly understood but Leishmania species and strain differences are important. To examine the relationship between clinical presentation, species and isoenzyme polymorphisms, 56 Leishmania isolates from distinct presentations of American tegumentary leishmaniasis (ATL) from Ecuador were analyzed. Methods: Isolates were characterized by multilocus enzyme electrophoresis for polymorphisms of 11 isoenzymes. Patients were infected in four different ecologic regions: highland and lowland jungle of the Pacific coast, Amazonian lowlands and Andean highlands. Results: Six Leishmania species constituting 21 zymodemes were identified: L. (Viannia) panamensis (21 isolates, 7 zymodemes), L. (V.) guyanensis (7 isolates, 4 zymodemes), L. (V.) braziliensis (5 isolates, 3 zymodemes), L. (Leishmania) mexicana (11 isolates, 4 zymodemes), L. (L.) amazonensis (10 isolates, 2 zymodemes) and L. (L.) major (2 isolates, 1 zymodeme). L. panamensis was the species most frequently identified in the Pacific region and was associated with several clinical variants of cutaneous disease (CL); eight cases of leishmaniasis recidiva cutis (LRC) found in the Pacific highlands were associated with 3 zymodemes of this species. Mucocutaneous leishmaniasis found only in the Amazonian focus was associated with 3 zymodemes of L. braziliensis. The papular variant of CL, Uta, found in the Andean highlands was related predominantly with a single zymodeme of L. mexicana. Conclusion: Our data show a high degree of phenotypic variation within species, and some evidence for associations between specific variants of ATL (i.e. Uta and LRC) and specific Leishmania zymodemes. This study further defines the geographic distribution of Leishmania species and clinical variants of ATL in Ecuador

Treatment of Hydrothermal-Liquefaction Wastewater with Crossflow UF for Oil and Particle Removal

This study aims to evaluate the application of ceramic ultrafiltration membranes in the crossflow mode for the separation of particles and oil in water emulsions (free oil droplets and micelles) from hydrothermal-liquefaction wastewater (HTL-WW) from the hydrothermal liquefaction of municipal sewage sludge. The experiments were carried out using one-channel TiO$_{2}$ membranes with pore sizes of 30, 10 and 5 nm. The results showed that the highest stable permeability could be achieved with a membrane-pore size of 10 nm, which experienced less fouling, especially through pore blockage, in comparison to the two other pore sizes. Instead of observing an increase in the permeability, the application of a higher feed temperature as well as backwash cycles led to a clear increase in irreversible fouling due to the presence of surfactants in the HTL-WW. Among several physical and chemical cleaning methods, alkaline cleaning at pH 12 proved to be the most efficient in removing fouling and maintaining stable performance on a long-term basis. Ceramic-membrane ultrafiltration can be considered as an adequate first-stage treatment of real HTL wastewater

On the onset of breathing mode in Hall thrusters and the role of electron mobility fluctuations

Breathing mode is an ionization instability which is observed ubiquitously in the operation of Hall thrusters. It is recognized as a relatively low frequency (10-30 kHz) longitudinal oscillation of the discharge current and the plasma parameters. Although breathing instability is widely studied in the literature, the conditions for its origin are not fully understood. In this work we investigate the mechanisms responsible for the origin of the breathing mode in Hall thrusters by using a numerical model, allowing us to highlight the importance of electron mobility fluctuations for the onset and self-sustenance of the instability. Our one-dimensional, fully fluid model of the thruster channel is calibrated against the measured discharge current signal for a 5 kW-class Hall thruster operating in a condition where breathing mode is fully developed. The corresponding steady, unstable configuration (base state) is numerically computed by applying the Selective Frequency Damping (SFD) method. Then, a series of numerical tests is performed to show the existence of a feedback loop involving fluctuations around the base state of the neutral density, electron mobility, and electric field. We show that oscillations of the electron mobility are mainly caused by variations of the neutral density and are in phase with them; this, in turn, induces oscillations of the electric field, which are in phase opposition. The electric field acts simultaneously on the electron temperature and on the ion dynamics, promoting the depletion and replenishment of neutrals in the chamber