Algunos tópicos econométricos de interés: Series de tiempo, pronósticos, no linealidad

El propósito de este artículo es presentar una revisión conceptual, técnica y de apli- caciones de algunos tópicos de econometría, considerados de relevancia, por sus aportes al análisis, entendimiento e interpretación de problemas teórico-aplicadosde la economía, así como por el nivel de desarrollo alcanzado en los últimos años. Series de tiempo univariadas y multivariadas, pronósticos y no linealidad, son contextualizados y revisados

Management of nursery practices for efficient ectomycorrhizal fungi application in the production of Quercus ilex

The application of ectomycorrhizal (ECM) fungi on forest nursery production is regarded as part of good management practice. However, before employing large scale inoculations in a nursery the interaction between ECM symbionts, growth substrate and fertilisation input should be studied to select the most suitable nursery practices for promoting plant growth and ECM colonisation. In this study, seedlings of Quercus ilex were inoculated with Paxillus involutus, Hebeloma mesophaeum or Cenococcum geophilum and grown in three different substrates commonly used in forest nurseries: peat-based compost, forest soil or composted pine bark. The effect of various fertilisation regimes was also studied. The choice of substrate had a significant effect on plant growth and ECM colonisation. The most appropriate combination of substrate and ECM fungus for Q. ilex growth and nutrition was peat and H. mesophaeum. Plants grown on a peat-based compost and inoculated with H. mesophaeum had a significantly greater biomass and leaf phosphorus concentration without fertilisation. Composted pine bark was found not to be suitable for growth or for mycorrhization. If the appropriate growth substrate is selected, it is possible to replace the use of chemical fertilisers by inoculation with selected ECM fungi. This results in a significant increase in plant development, and thus ECM fungi can be recommended as a more environmental friendly biotechnological approach to plant management in the nursery.info:eu-repo/semantics/publishedVersio

Bioremediation on anthropogenic affected areas: Ectomycorrhizal and plant growth bacteria as promoters of pine establishment

The recovery of damaged areas due to inadequate farming policies and increased industrial sediment deposition, have contaminated not only soil and surrounding areas but also other natural resources. The potential use of disturbed sites for agriculture and forestry is jeopardised and their remediation is critical and expensive. The utilization of biotechnological tools, such as plant growth promoting bacteria (PGPB) and ectomycorrhizal fungi (ECM) could help remediation of such soils as they can be used as plant facilitators for land recovery. The aim of this study was to assess the potential of PGPB and ECM to enhance the growth of Pinus pinaster in antropogenic sediments and forest soil. Pine seedlings were inoculated with Suillus bovinus, Pisolithus tinctorius and Paxillus involutus, and co-inocualted with Bacillus spp. and Mesorhizobium spp. Plants were harvested after 6 month growth and parametric and nutritional data determined. Results show that P. involutus increased seedling growth(height) in industrial sediments soil, whereas in forest soil, plant performance was higher with S. bovinus. The effect of inoculation on the fungal communityin seedling roots and bacterial rhizosphere was also analysed by PCR-DGGE and differences arose between inoculated and uninoculated soil, indicating that PGPB and ECM may significantly influence the plant growth performance over a period of time. The study shows that PGPB and ECM fungi may be used as a biotechnology tool contributing to the successful plant establishment in disturbed environments

Biodegradation of 2-fluorophenol in a rotating biological contactor

N/

Voltage-driven quantum oscillations in graphene

We predict unusual (for non-relativistic quantum mechanics) electron states in graphene, which are localized within a finite-width potential barrier. The density of localized states in the sufficiently high and/or wide graphene barrier exhibits a number of singularities at certain values of the energy. Such singularities provide quantum oscillations of both the transport (e.g., conductivity) and thermodynamic properties of graphene - when increasing the barrier height and/or width, similarly to the well-known Shubnikov-de-Haas (SdH) oscillations of conductivity in pure metals. However, here the SdH-like oscillations are driven by an electric field instead of the usual magnetically-driven SdH-oscillations.Comment: 4 pages, 4 figure

Diverse Arbuscular Mycorrhizal Fungi (AMF) communities colonize plants inhabiting a constructed wetland for wastewater treatment

Constructed wetlands (CWs) are biological wastewater treatment systems that comprise several components where plants and associated organisms play an important role in water depuration. Microbial studies emphasize bacterial dynamics, whereas studies of arbuscular mycorrhizal fungi (AMF) are scarce and the functional role of AMF in aquatic and wetland plants is poorly understood. The aim of this study was to analyze the AMF communities colonizing the roots of Canna indica, Canna flaccida, and Watsonia borbonica inhabiting a CW treating wastewater of a tourism unit. The dynamics of the AMF communities were evaluated by Denaturing Gradient Gel Electrophoresis (DGGE) of 18S rRNA gene amplification products along cold (C) and hot (H) seasons for three consecutive years. DGGE profiles allowed the estimation of AMF species richness (S), and Shannon-Wienner (H) and Pielou (J) indexes, for the different plant species, showing differences between species and along the years. Excised bands from DGGE were analyzed and identified through sequencing for arbuscular mycorrhiza, revealing the presence of AMF strains closely related to Glomus sp., Rhizophagus sp. and Acaulospora sp. genera. Concomitant water quality analyses showed that the system was effective in organic and nutrient removal during the sampling period. Findings from this study suggest that AMF diversity found in the CW is influenced by the water constituents, season, and plant species.info:eu-repo/semantics/publishedVersio

MDMA intoxication in a potential organ donor with cardiac arrest

Amphetamine and its derivatives’ consumption is still an important public health issue, namely in terms of compounds variability and disposition to consumers. However, some of them, like MDMA, still live in the illicit market, with continuous success. Nevertheless, there is always new information and data on MDMA intoxication, both in vivo and in post-mortem context. The authors report an intoxication case with MDMA, in an 18 years old male, considered a potential organ donor after a cardiac arrest. Whole blood samples were collected in vivo, at the Emergency Room (ER), and post-mortem, at the National Institute of Legal Medicine and Forensic Sciences. After a general screening procedure, samples were extracted by SPE (OASIS® MCX), followed by GC-MS analysis. The whole blood post-mortem sample was positive for lidocaine (< 500 ng/mL), compatible with the ER intervention, and positive for MDMA (2278 ng/mL) and MDA (49 ng/mL), while whole blood samples collected in vivo (during the maintenance of the individual under advanced life support), were positive for MDMA (504 ng/mL to 1918 ng/mL) and MDA (20 ng/mL to 89 ng/mL). Samples were negative for other substances, namely ethanol, other drugs of abuse and medicines.Results interpretation is pivotal to understand the behaviour of the substance. Thus, in this case, MDMA post-mortem behaviour should be carefully evaluated, considering as possible influencers, in the specific context of the case, the time lapse between death verification, maintenance of the advanced life support and body manipulation for organ collection purposes. Also referred and discussed is the ante-mortem/post-mortem ratio of MDMA obtained values, compared with literature references. There is no doubt that death was due to MDMA intoxication, but information from the analysis performed on the in vivo samples suggests that this type of sample should also be considered, in a complementary role, whenever possible.info:eu-repo/semantics/submittedVersio

Spatial-temporal changes in removal of fecal indicators and diversity of bacterial communities in a constructed wetland with ornamental plants

The present study was undertaken in a constructed wetland (CW), setup in a tourism house, for domestic wastewater treatment. The influence of season variations on the abundance of fecal indicator organisms (total coliforms and Escherichia coli) in the wastewater and in the substrate and the roots of plants inhabiting the inlet and outlet zones of the CW was evaluated along three consecutive years. The structure and diversity of bacterial communities associated to the CW’s substrate of inlet and outlet zones was also analyzed overtime. Wastewater was characterized for physicochemical and microbiological parameters and the bacterial communities colonizing the substrate surface, were analyzed by Denaturing Gradient Gel Electrophoresis (DGGE). The CW was effective in removing COD, BOD5, TSS, PO43−, NH4+, NO3−, and NO2− . It was also effective in removing fecal indicators, with a generalized decrease of total coliforms and E. coli in the substrate and in the wastewater from inlet to outlet of up to 2–3 log. The structure and composition of bacterial communities associated with the substrate was mainly influenced by the year rather than by the season or the CW zone.info:eu-repo/semantics/publishedVersio