Ejecución contractual en tiempos de pandemia

La covid-19 ha generado una profunda crisis de gran impacto sanitario, social y económico. Entre los ámbitos afectados por la pandemia y por las medidas adoptadas para combatirla se encuentra la contratación pública, ya que fueron miles los contratos afectados en su ejecución que repercutían en los usuarios, los contratistas y las administraciones públicas. En este trabajo se toma como punto de partida la posible consideración de la covid-19 como causa de fuerza mayor y, posteriormente, se analizan los aspectos esenciales del régimen especial establecido por el art. 34 del RDL 8/2020. Así, se reflexiona sobre su ámbito de aplicación, los contratos excluidos, los efectos en la ejecución de los contratos, el régimen de suspensión, los conceptos indemnizables y los requisitos del procedimiento para la indemnización de los daños y perjuicios sufridos por el contratista. Al mismo tiempo se destacan algunos problemas de la aplicación de esta norma especial, que deja en una posición peor a los contratistas, así como determinadas carencias de esta regulación y de su interpretación por la Abogacía del Estado. Covid-19 has generated a profound crisis with a major health, social and economic impact. Among the areas affected by the pandemic and the measures adopted to combat it is public procurement, as thousands of contracts were affected in their execution, with repercussions for users, contractors and public administrations. This paper takes as its starting point the possible consideration of covid-19 as a cause of force majeure and, subsequently, analyses the essential aspects of the special regime established by article 34 of RDL 8/2020. Thus, it reflects on its scope of application, the excluded contracts, the effects on the performance of contracts, the suspension regime, the compensable concepts and the requirements of the procedure for the compensation of damages suffered by the contractor. At the same time, some problems in the application of this special rule are highlighted, which leaves contractors in a worse position, as well as certain shortcomings of this regulation and its interpretation by the State Attorney’s Office

The effects of the use of organic solid wastes on the growth of citrus trees

Two types of organic solid wastes were selected to be applied in a citrus orchard: the sewage sludge (the most common on the settlements) and the manure (the most common on the agricultural fields). The sewage sludge is a residue originated from the wastewater treatment - the solid phase. Its application as an organic fertilizer may represent an alternative to the pollution effects in nature. In an orchard of orange-trees (Citrus sinensis [L.] Osbeck), the application of sludge was compared with the application of manure and with the control in order to observe the growth response of the trees. Biometric methods where used - number of leaves per tree, diameter of the trunk, leaf area, specific leaf areas and leaf chlorophyll content. In general, the citrus plants response to the application of sewage sludge and manure was positive for the plant growth, compared to the control. The application of the manure, and especially the sewage sludge (once this fertilizer / soil amendment is available in larger amounts) may be a profitable alternative application to the use of mineral fertilizers and to other soil amendments. Moreover, as the possible destinations of sewage sludge (sea, deposition in land fields, incineration) provoke environmental problems, its agricultural reuse is essential to avoid those problems, when correctly applied in relation to trace elements and to pathogenic parameters. The reuse of this solid waste may be a clean and a safe technique to preserve the environment contamination

Pasa assay for diagnosing insecticide resistance in the horn fly population in Rondonia.

Knockdown (kdr) resistance is caused by a reduction in the sensitivity of the insectnnervous system to pyrethroids. Kdr resistance in field populations of horn flies can severely limit pyrethroid usefulness in fly control programs. Early detection and characterization of kdr resistance are critical to the development of resistance management strategies. Studies at the Embrapa Rondonia experimental farm, Porto Velho, RO and at Knipling-Bushland U.S. Livestock Insects Research Laboratory, USDA/ARS, Kerrville, TX were conducted to verify the genotypes of the Embrapa Rondonia horn fly population. First, the population was assessed using cypermethrin-impregnated filter papers produced at the Embrapa Rondonia Animal Health Laboratory. Horn flies from an untreated cattle herd were caught with a sweep net and used for bioassays. Flies were exposed for two hours to filter papers treated with technical grade cypermethrin in acetone, using cypermethrin concentrations from 0.01 ?g to 3,200 ?g/cm2. Control flies were exposed to filter papers treated only with acetone. Three groups of ten flies were exposed at each concentration. All flies exposed to cypermethrin concentrations between 800-3,200 ?g/cm2 died. Genomic DNA was isolated from individual adult flies that survived bioassay concentrations of 200-400 ?g/cm2 and 30 flies tested by PASA (PCR amplification of specific alleles) assay for the presence of a specific nucleotide substitution in the sodium channel gene sequence that has been associated with kdr resistance in horn flies. PASA was performed using two parallel PCRs, with each PCR containing three sets of primers, and genomic DNA to detect pyrethroid resistance-associated nucleotide differences in individual flies. Two primers, FG 234 and FG 243, provided a positive control PCR product while the products of primer FG 138 with primer FG 130 (reaction 1) or with primer FG 134 (reaction 2) produced diagnostic products for genotyping the kdr allele. Reaction products were visualized after 4% agarose gel electrophoresis followed by UV illumination after staining with Syber Green. The kdr allele was not detected in flies from the Embrapa Rondonia population, which was considered a pyrethroid susceptible homozygous (SS) population. This result was expected for this horn fly population as there is no report of treatment with pyrethroids in the last six years

A review of networked microgrid protection: Architectures, challenges, solutions, and future trends

The design and selection of advanced protection schemes have become essential for the reliable and secure operation of networked microgrids. Various protection schemes that allow the correct operation of microgrids have been proposed for individual systems in different topologies and connections. Nevertheless, the protection schemes for networked microgrids are still in development, and further research is required to design and operate advanced protection in interconnected systems. The interconnection of these microgrids in different nodes with various interconnection technologies increases the fault occurrence and complicates the protection operation. This paper aims to point out the challenges in developing protection for networked microgrids, potential solutions, and research areas that need to be addressed for their development. First, this article presents a systematic analysis of the different microgrid clusters proposed since 2016, including several architectures of networked microgrids, operation modes, components, and utilization of renewable sources, which have not been widely explored in previous review papers. Second, the paper presents a discussion on the protection systems currently available for microgrid clusters, current challenges, and solutions that have been proposed for these systems. Finally, it discusses the trend of protection schemes in networked microgrids and presents some conclusions related to implementation

Therapeutical interest of statins in the treatment of atherosclerosis

Los inhibidores de la HMG-Co A reductasa o estatinas, son fármacos muy utilizados en el tratamiento de la hipercolesterolemia, ya que consiguen disminuir la concentración plamática de lipoproteína de baja densidad (LDL) regulando la síntesis endógena de colesterol y por tanto, de receptores para LDL. Recientemente se ha comprobado como el tratamiento prolongado con estos fármacos disminuyen la mortalidad y morbilidad cardiovascular. Este fenómeno puede explicarse por los efectos beneficiosos directos de las estatinas en el desarrollo de la placa de ateroma. Las estatinas disminuyen la proliferación y migración de células de musculatura lisa vascular e inducen apoptosis de estas células. También previenen la oxidación de LDL y la formación de células espumosas, reducen la respuesta inflamatoria asociada a la aterosclerosis, normalizan los fenómenos de coagulación y fibrinolisis y por último mejoran significativamente la función endotelial. Todas estas propiedades parecen estar mediadas compuestos isoprenoides intermediarios de la ruta metabólica de la HMG-Co A reductasa, y son independientes de la concentración de colesterol en el medio. Por tanto, las estatinas también podrían ser utilizadas en enfermedades asociadas a disfunción endotelial independientemente de las cifras analíticas de LDL, tal y como sucede en la hipertensión.HMG-Co A reductase inhibitors or statins, are widely used drugs in the treatment of hypercholesterolemia. They lower plasmatic concentration of low density lipoprotein (LDL) by regulating cholesterol synthesis and consequently synthesis of LDL receptors. Chronic treatment with these drugs has recently shown to be able to reduce cardiovascular-related morbidity and mortality. This fact could be explained by a direct benefic effect of statins in development of atherosclerotic plaque. Statins reduce vascular smooth muscle cell proliferation and migration , as well as they induce apoptosis of these cells. They also prevent LDL oxidation and foam cell formation, reducing inflammatory response associated to atherosclerosis, normalising coagulation and fibronolysis and improving endothelial function. All these properties seem to be mediated by intermediary isoprenoid compounds from HMG-Co A reductase metabolic pathway and do not depend of cholesterol concentration in the medium. Thus, statins could also be used in the treatment of some diseases associated to endothelial disfunction, independently of analytical LDL values, like hypertension