118,266 research outputs found
Intertidal mussels as ecosystem engineers: their associated invertebrate biodiversity under contrasting wave exposures
No full textMussels often act as ecosystem engineers in rocky intertidal habitats, favoring the occurrence of many small invertebrates by increasing habitat complexity and improving local environmental conditions. This study tests the hypothesis that invertebrate assemblages from intertidal mussel beds differ between wave-sheltered and wave-exposed habitats. To this aim, we surveyed exposed and sheltered sites spanning 350 km of coastline in Nova Scotia, Canada. We identified all invertebrates and measured their abundance in replicate quadrats that were fully covered by mussels. In total, we found 50 invertebrate taxa living in these mussel beds. Multivariate analyses revealed that the composition of invertebrate assemblages differed significantly between both habitat types. Exposed habitats supported a greater species richness, and the species that mainly explained the compositional difference between both environments were more abundant in exposed ones. Assemblages were taxonomically dominated by arthropods, annelids, and molluscs and numerically dominated by tubificid oligochaetes regardless of exposure. Our results suggest that exposed habitats may favor the occurrence of filter-feeders, such as barnacles, and sheltered habitats the occurrence of predators, such as small crabs and sea stars, in intertidal mussel beds from the NW Atlantic coast.Fil: Arribas, Lorena Pilar. Saint Francis Xavier University; Canadá. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Donnarumma, Luigia. Saint Francis Xavier University; Canadá. Seconda Universita Degli Studi Di Napoli; ItaliaFil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Scrosati, Ricardo Augusto. Saint Francis Xavier University; Canad
Il fenomeno della dismissione dell'edilizia industriale e le potenzialità di recupero e riconversione funzionale
No full textIdentification of Listeria monocytogenes by colony hybridization test using the virulence-associated hly and inlA genes as probes.
No full textWe developed a method of identification of Listeria monocytogenes based on colony hybridization with nonradioactively labeled DNA probes, represented by the hly and inlA virulence-associated genes. The procedure described in this paper results simple, rapid, specific and reproducible. Since it can be performed in a short time, the above technique can be applied to detect L. monocytogenes from different source and constitutes a noteworthy and alternative tool to identify this gram-positive pathogenic bacterium
Active antiskid system for handling improvement in motorbikes controlled by fuzzy logic
No full textActive antiskid systems for high performance motorbikes are difficult to implement due to the necessity to combine performance, equilibrium, handling and safety. In order to design and optimize a fuzzy controlled antiskid system for motorbikes a fuzzy model of the pilot was applied to a lumped-mass model of the motorcycle (two different models have been considered). The fuzzy pilot acts on the steering angle to control trajectory, yaw angle, yaw velocity and roll angle. Throttle position vs. time curve, gear and an adherence model between tire and road are given as input. The fuzzy pilot is implemented with Matlab/Simulink, and simply tries to keep equilibrium. Only measurable inputs were given as input variables of the antiskid fuzzy controller. The output is the percent reduction in throttle position. The motorcycle-fuzzy-pilot model proved to be quite accurate. Motorcycle maximum velocity resulted higher than the real one due to the simplifying hypothesis. In curves the fuzzy pilot is less efficient than the real pilot. In fact there was a low frequency oscillation around the optimum steering angle. This fuzzy controlled antiskid proved to work quite well since equilibrium is attained also in critical situations where the motorcycle-fuzzy-pilot model alone fails to keep equilibrium
Fuzzy control system for recovering direction after spinning
No full textThe progressive increase of tire-size has concurred to a sensitive improvement of the adherence with consequent increase of car safety. However, the wide tires have problems to expel the water in excess in heavy rain condition. For this reason the phenomenon of the aquaplaning is increasingly felt and is the cause of several automotive accidents. It is not a case that nearly all tire manufacturers supply "rain" tires and adherence in wet conditions is highly advertised. A typical accident happens when aquaplaning occurs in motorway at high speed. One or more tires lose adherence and the car begins to spin. If the pilot is not able to regain the initial direction, the car may hit the guardrail or another car. In this case the modern control systems like the ESP (Electronic Stability Program) and the ASR (Anti Skid Regelung) do not have time or are not able to manage a pre-spin or spin situation at elevated slip-angles. In this paper, a fuzzy control system able to deal with these conditions is introduced. The car has been simulated with a 9 DOF lumped-mass model that does not take into account suspensions and it considers a rigid car on smooth asphalt. The model of adhesion of the tire, instead, takes into account the effect of transverse forces on the longitudinal adherence. An expert pilot controls a high-speed spin with difficulty also. In this paper, a fuzzy control system that is able to control the brake torque on each single tire has been considered. The fuzzy control system works quite well and the car does not even enter in a true spin if enough adherence is present or if the slippery zone on asphalt is limited
FUZZY LOGIC CONTROLLING MOTORBIKES ANTISKID
No full textActive antiskid systems for high performance motorbikes are difficult to implement due to the necessity to combine performance, equilibrium, handling and safety. In order to design and optimize a fuzzy controlled antiskid system for motorbikes, a fuzzy model of the pilot was applied to a lumped-mass model of the motorcycle (two different models have been considered). The fuzzy model acts on the steering angle to control trajectory, yaw angle, yaw velocity and roll angle
Analisi storico-architettonica e riuso sostenibile dei conventi cappuccini dell’antica Provincia Religiosa di Basilicata-Salerno
No full textQuantitative dominances of taxa structuring the macrozoobenthic communities living in different coastal habitats.
No full textThe aim of this study was to quantify the dominance of macrozoobenthic taxa structuring the benthic assemblages associated to 6 coastal habitats, which occur from the mesolittoral to the circalittoral zone of the Campania coast. Crustaceans, polychaetes and molluscs were the main taxonomic groups structuring all the benthic assemblages, representing an average of 89.20% of the total taxa. However, each habitat showed the dominance of only one peculiar taxon
Invasion of cultured human cells by Streptococcus pyogenes.
No full textThe invasive capacity of streptococcal strains belonging to groups A and B was evaluated by infecting human epithelial and endothelial cells and monitoring the number of viable intracellular bacteria at different times postinfection. All strains tested entered eukaryotic cells (HeLa, HEp2 and HUVE), with Streptococcus pyogenes exhibiting a higher invasion efficiency than group B streptococci (GBS). No intracellular multiplication was observed, and GBS remained viable 24 h postinfection, whereas S. pyogenes were gradually killed. We found that cytochalasin D almost completely inhibited internalization of all bacterial strains, whereas colchicine had no effect, indicating that host microfilaments play a major role in bacterial internalization. Moreover, the use of the lysosomotropic agent ammonium chloride enabled us to demonstrate that a pH increase in the intracellular vesicles did not affect streptococcal entry. These results were documented by electron microscopic observations which revealed the different steps in the invasion pathway, including a fusion event between phagosomes containing S. pyogenes and lysosomes
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