509 research outputs found

    Discriminative Auditory Fear Learning Requires Both Tuned and Nontuned Auditory Pathways to the Amygdala

    Get PDF
    The auditory system has two parallel streams in the brain that have been implicated in auditory fear learning. The lemniscal stream has selective neurons that are tonotopically organized and is thought to be important for sound discrimination. The nonlemniscal stream has less selective neurons, which are not tonotopically organized, and is thought to be important for multimodal processing and for several forms of learning. Therefore, it has been hypothesized that the lemniscal, but not the nonlemniscal, pathway supports discriminative fear to auditory cues. To test this hypothesis we assessed the effect of electrolytic lesions to the ventral, or medial, division of the medial geniculate nucleus (MGv or MGm, which correspond, respectively, to the lemniscal and the nonlemniscal auditory pathway to amygdala) on the acquisition, expression and extinction of fear responses in discriminative auditory fear conditioning, where one tone is followed by shock (conditioned stimulus, CS(+)), and another is not (CS(-)). Here we show that with single-trial conditioning control, MGv- and MGm-lesioned male rats acquire nondiscriminative fear of both the CS(+) and the CS(-). However, after multiple-trial conditioning, control rats discriminate between the CS(+) and CS(-), whereas MGv- and MGm-lesioned do not. Furthermore, post-training lesions of MGm, but not MGv, lead to impaired expression of discriminative fear. Finally, MGm-lesioned rats display high levels of freezing to both the CS(+) and CS(-) even after an extinction session to the CS(+). In summary, our findings suggest that the lemniscal pathway is important for discriminative learning, whereas the nonlemniscal is important for negatively regulating fear responses

    Experimental Investigation Of Disruptive Burning Phenomena On Nanofuel Droplets

    Get PDF
    The transport sector plays a crucial aspect in society and economic evolution. However, improper energy management has negatively impacted health and the environment. Thus, the use of sustainable and green fuels in the aeronautical industry has been implemented due to environmental concerns and the depletion of fossil fuels. The introduction of biofuels, a renewable energy source in the transportation sector, has shown advantages in terms of pollutant reduction. Recently, the addition of nanoparticles in the combustion of biofuel has been studied with the purpose of enhancing its combustion characteristics. Consequently, the present work evaluates nanofuel single droplet in a falling droplet method. In this way, the fiber suspension effect was neglected, and droplets in a size of 250 μm were evaluated. To this end, a comparison between pure biofuel and a nanofuel at two furnace temperatures (T = 800 ºC and T = 1000 ºC) was performed. The results reveal that disruptive burning phenomena occur when aluminum nanoparticles are added to the biofuel. Consequently, a micro-explosion determines the end of the droplet lifetime, mainly affected by the furnace temperature.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

    Sepsis: the need for tolerance not complacency

    Get PDF
    Sepsis is a life-threatening condition that arises as a systemic inflammatory response syndrome to an infection. Its uncontrolled progression can in frequent cases lead to multiple organ failure, which is still associated with high mortality rates. Modern antibiotics made clear that the infection is only an initiating, and not always necessary, event of this syndrome as many patients with sepsis die despite effective eradication of the inciting pathogen. This observation critically contributed to a paradigm shift that focused the pathogenesis of sepsis on the host and not on the pathogen. However, therapeutic strategies based on the inhibition of proinflammatory critical mediators of sepsis or immunostimulation have so far failed to improve sepsis outcome and, therefore, this condition urgently needs transformative therapeutic ideas and strategies. Here we argue that the induction of tolerance, a defence strategy that minimises the impact of an infection on organ function without directly affecting the pathogen burden, is perhaps the missing but essential element to add to the current components of sepsis care and treatment.IGC Integrative Biology and Biomedicine (IBB) PhD Program, FCT, European Research Council (ERC-2014-CoG 647888-iPROTECTION)

    Reação de cultivares de pimentas e pimentões à mancha bacteriana.

    Get PDF
    O objetivo deste trabalho foi avaliar, em casa de vegetação, a resistencia de sete cultivares (BRS Garça, BRS Sarakura, BRS Mari, BRS Ema, BRS Seriema, BRS Moema, BRS Brazilândia) à mancha bacteriana, causada por Zanthomonas euvesicatoria.Resumo 642-

    The influence of aluminium particles in a Hydroprocessed Vegetable Oil combustion

    Get PDF
    The present work experimentally investigates single droplet combustion to understand the effect of aluminum particles when added to a biofuel. Experiments are carried out in a drop tube furnace to evaluate the influence of size and concentration of the aluminum particles. Two different sizes (40 nm and 5 μm) and two concentrations (0.5 and 1.0 wt.%) are studied at 1000 °C. The addition of aluminum particles improves biofuel combustion. Decreasing the particle size and increasing the particle concentration leads to a significant enhancement in the burning rate compared to the pure HVO. Micro-explosions are detected at the end of droplet lifetime when particles are added to biofuel.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

    Analysis of the Topics of Research of Brazilian Researchers Acting in the Areas of Engineering

    Get PDF
    The production and publication of scientific works have increased significantly in the last years, being the Internet the main factor of access and diffusion of these. In view of this, researchers from several areas of knowledge have carried out several studies on scientific production data in order to analyze phenomena and trends about science. The understanding of how research has evolved can, for example, serve as a basis for building scientific policies for further advances in science and stimulating research groups to become more productive. In this context, the objective of this work is to analyze the main research topics investigated along the trajectory of the Brazilian science of researchers working in the areas of engineering, in order to map scientific knowledge and identify topics in highlights. To this end, studies are carried out on the frequency and relationship of the keywords of the set of scientific articles registered in the existing curricula in the Lattes Platform of each one of the selected researchers, counting with the aid of bibliometric analysis features

    Different meanings for cummingtonite-hornblende association in plutonic rocks (Iberian Massif, Portugal)

    Get PDF
    Cummingtonite-grunerite series is frequently related with metamorphism or volcanic environments but rarely described as belonging to a plutonic assemblage [1]. Recently, in Iberian Massif (Portugal), there have been several references [2,3,4,5] of this Fe-Mg amphibole intimately associated with Ca amphiboles (mainly hornblende) on plutonic rocks. Different textural relations between two amphibole types have been argued to for a primary (igneous) or subsolidus metamorphic origin for Fe-Mg amphibole. Cummingtonite-grunerite (Cum, hereafter all abbreviation from [6]) from gabbros and diorites Carrascal Massif (Central Iberian Zone) occurs as tiny exsolution lamellae within a dominant hornblende (Hbl) crystal. Their textural occurrence agrees with the subsolidus growth of the Fe-Mg amphibole reflecting the equation Hbl+ Qtz= Cum + An + H2O [7]. Nevertheless, on Hospitais tonalite (Ossa-Morena Zone) Cum occur as euhedral to subhedral cores usually mantled by Hbl. Although seldom described in literature, Cum on Hospitais tonalite was interpreted as an igneous crystallizing early phase. As a consequence of the high water content of calc-alkaline magmas, the Fe-Mg amphibole should reflect the equation Opx+H2O = Cum+Mag+SiO2+H2 [8]. The similarity between Mg # on Cum and Hbl from tonalitic rocks suggests an equilibrium crystallizing assemblage as pointed by Wones and Gilbert [9] for a hypabyssal igneous suite. Considering that the Cum spectrum analyses from both occurrences exhibited a clear overlap; Carrascal gabbro-dorites (Mg#: 0.49-0.64; Al2O3: 0.7-2.37%; TiO2: 0.01-0.37%) and Hospitais tonalite (Mg#: 0.43-0.53; Al2O3: 1.22-2.44 %; TiO2; 0.05-0.27%), textural relations should be the main (only?) tool to decipher between igneous vs metamorphic growth. More detailed petrographic studies on plutonic rocks from Iberian Massif are needed to ascertain the petrogenetic significance of the association Cum-Hbl

    The Impact of High Particles Concentration in a Biofuel Droplet Combustion

    Get PDF
    Aviation is one of the largest transportation sectors and is operated on fossil fuels, being responsible for about 2% of global CO2 emissions. In order to reduce the environmental impact, biofuels emerged as a promising solution. Additionally, a possible approach to improve the performance of biofuels is to add nanoparticles, leading to the concept of nanofuel. The present work evaluates the nanofuel droplet combustion of a biofuel containing high aluminum particle concentrations. To enhance the nanofuel stability, a preliminary study focusing on the addition of a surfactant was mandatory. Particle size of 40 nm and three particle concentrations from 1.0 to 4.0 wt.% were considered. The results show that the oleic acid effectively improves the stability, and no visible oxidation of the nanoparticles was reported. Regarding the single droplet combustion, the observations show that the addition of nanoparticles promotes micro-explosions, contrary to the combustion of pure biofuel, and increases the overall droplet burning rate.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio
    corecore