Gestão de fertilizantes de libertação gradual de nutrientes em relvados municipais

Os fertilizantes de libertação lenta podem ajudar a reduzir as perdas de azoto (N) para o meio ambiente, disponibilizando os nutrientes à medida da necessidade das plantas. Neste trabalho apresentam-se resultados da utilização de fertilizantes de libertação gradual de nutrientes em relvados da Câmara Municipal de Valpaços. Foram implementados os tratamentos: Floranid permanent 16:7:15 (adubo de libertação lenta, IBDU/Isodur); Basacote plus 9M 16:8:12 (adubo de libertação controlada, copolímero etlileno acrílico); Nitroteck 20:8:10 (fertilizante estabilizado, DCD como inibidor da nitrificação + revestimento de politerpeno); Nitrolusal (20,5% N); e uma modalidade testemunha sem N. Os fertilizantes foram aplicados à razão de 120 kg N ha-1 em 11 de Março de 2007. O nitrolusal foi fracionado em duas aplicações. Determinou-se a produção de biomassa, em cortes sequênciais de março a setembro, a dinâmica do N, recorrendo a membranas de troca aniónica enterradas no solo, e a dinâmica da vegetação através de levantamentos florísticos. Foram calculados índices de eficiência económica do uso dos fertilizantes. A produção de matéria seca foi significativamente diferente entre tratamentos. Basacote produziu mais que testemunha e menos que Floranid, Nitroteck e Nitrolusal. Basacote retardou a libertação de N relativamente aos outros fertilizantes. Os índices de eficiência económica foram favoráveis a Nitroteck e desfavoráveis a Basacote, devido à grande diferença nos preços

Nitrogen-use efficiency and economic efficiency of slow-release N fertilisers applied to irrigated turfs in a Mediterranean environment

The effect of three fertilisers that delay the bioavailability of nitrogen (N) in the soil was compared with ammonium nitrate and a zero N control in two irrigated turfs in NE Portugal. The fertilisers used were: Floranid permanent 16-7-15 (slow-release, IBDU/Isodur fertiliser); Basacote plus 9M 16-8-12 (controlled-release fertiliser, copolymer ethylene acrylic); Nitroteck 20-8-10 (stabilized fertiliser, dicyandiamide as nitrification inhibitor + coating with polyterpene) and Nitrolusal (ammonium nitrate, 20.5% N), applied all at a rate of 120 kg N ha-1. Nitrolusal was split into two fractions of 60 kg N ha-1. Phosphorus (P) and potassium (K) rates were balanced among treatments by using superphosphate (18% P2O5) and potassium chloride (60% K2O). The turf dry matter (DM) yield and N concentration in dry material were determined from several cuts of biomass throughout the growing season. Based on DM yield, N concentration in dry material and fertilisation costs, indices of N use efficiency and economic efficiency were estimated. Soil nitrate levels were monitored by using anion exchange membranes inserted directly into the soil. Basacote gave significantly lower DM yields than the other fertilised treatments. The apparent N recovery of Basacote was also the lowest. The results showed that Basacote released less N than that required for an adequate plant growth in the beginning of the growing season, hampered the flush of spring growth. Furthermore, the release period of this Basacote formulation, in the environmental conditions of these experiments, seemed to be longer than the length of the growing season. Nitroteck and Floranid yielded similar or even higher DM and apparent N recovery values than did Nitrolusal. The indices of economic efficiency ordered the fertilisers as Nitroteck > Nitrolusal > Floranid > Basacote or Nitrolusal > Nitroteck > Floranid > Basacote, if the costs of P and K fertilisers used to balance the P and K rates in the experimental design were, respectively, taken or not taken into account

Relaxation- and Decoherence-free subspaces in networks of weakly and strongly coupled resonators

We consider a network of interacting resonators and analyze the physical ingredients that enable the emergence of relaxation-free and decoherence-free subspaces. We investigate two different situations: i) when the whole network interacts with a common reservoir and ii) when each resonator, strongly coupled to each other, interacts with its own reservoir. Our main result is that both subspaces are generated when all the resonators couple with the same group of reservoir modes, thus building up a correlation (among these modes), which has the potential to shield particular network states against relaxation and/or decoherence.Comment: 5 page

Long-term effects of chronic cocaine exposure throughout adolescence on anxiety and stress responsivity in a wistar rat model

Adolescents display increased vulnerability to engage in drug experimentation. This is often considered a risk factor for later drug abuse. In this scenario, the permanent effects of cocaine exposure during adolescence on anxiety levels and stress responsivity, which may result in behavioral phenotypes prone to addiction, are now starting to be unveiled. Thus, the purpose of the present study was to evaluate the long-lasting effects of chronic cocaine administration during adolescence, on anxiety-like behavior and on stress response. Adolescent male Wistar rats were daily administered 45-mg cocaine/kg of body weight in three equal intraperitoneal doses with 1-h interval, from postnatal day (PND) 35 to 50. The effects of cocaine administration on anxiety levels, assessed in the Elevated Plus Maze (EPM), and on social stress response, assessed in the resident-intruder paradigm (R/I), were evaluated 10 days after withdrawal, when rats were reaching the adulthood. The underlying dopaminergic activity, and the corticosterone and testosterone levels were determined. Our results showed that cocaine induced long-lasting alterations in the hypothalamus-pituitary-adrenals (HPA) axis function and in testosterone levels. Such alterations resulted in significant and enduring changes in behavioral responses to environmental challenges, such as the EPM and R/I, including the evaluation of potential threats that may lead to high-risk behavior and low-benefit choices. This was further supported by an altered dopaminergic function in the amygdala and hippocampus. The present findings provide new insights into how the use of cocaine during adolescent development may modulate emotional behavior later in life. Compromised ability to recognize and deal with potential threats is an important risk factor to perpetuate compulsive drug seeking and relapse susceptibility.info:eu-repo/semantics/publishedVersio