1,450 research outputs found

    Checklist of free-living nematode species in the transitional environment of Lake Varano (Southern Italy)

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    Llista patró d’espècies de nematodes de vida lliure a l’ambient de transició del llac Varano (sud d’Itàlia)Aquest estudi documenta per primera vegada la composició taxonòmica de la comunitat de nematodes i el nombre d’espècies de nematodes de vida lliure presents al llac Varano, al sud de la mar Adriàtica (Itàlia). La comunitat de nematodes estava composta principalment per espècies típiques dels sediments fins predominants en ambients de transició (TE). En conjunt, es va registrar un nombre elevat d’espècies de nematodes (56) pertanyents a 36 gèneres de 17 famílies. Aquests valors són comparables en gran mesura amb els registrats en altres TE italians, però inferiors als registrats en altres sistemes d’aigües salabroses europeus, probablement en relació amb el baix nivell de salinitat del llac Varano. Es van identificar quaranta taxons a nivell d’espècie, la qual cosa incrementa el nombre d’espècies conegudes de nematodes marins a les costes italianes de 443 a 463, a la conca de l’Adriàtica de 310 a 313 i al sud de la mar Adriàtica de 37 a 77. Atesa la importància d’aquest fílum per a la valoració de la qualitat ecològica i la gran vulnerabilitat dels ecosistemes de la mar Adriàtica, s’hauria de planificar la intensificació de les accions de mostreig, especialment a la part centre-meridional de la conca. Un pla així proporcionaria nous coneixements de la biogeografia d’un dels components més importants del bentos i podria aportar nova informació sobre els efectes de l’escalfament climàtic a la mar Adriàtica.This study documents for the first time the taxonomic composition of the nematode community and the number of free–living nematode species in Lake Varano, Southern Adriatic Sea, Italy. The nematode community was mainly composed of species typical of fine sediments that usually prevail in transitional environments (TEs). An overall high number of nematode species was recorded (55), belonging to 36 genera in 17 families. These values are highly comparable to those reported for other Italian TEs, but appear lower than those recorded in other European brackish–water systems, probably in relation to the low salinity range of Lake Varano. Forty taxa were identified up to species level, thus increasing the number of the nematode marine species known for the Italian coasts from 443 to 463, for the Adriatic basin from 310 to 313, and for the Southern Adriatic sector from 37 to 77. Considering the importance of this phylum in the assessment of ecological quality and the great vulnerability of the Adriatic Sea ecosystems, an intensification of sampling efforts should be planned, especially in the Central–Southern part of the basin. Such a plan would provide new insights into the biogeography of one of the most important components of the benthic domain and potentially yield new information about the climate warming effects on the Adriatic Sea.Lista patrón de especies de nematodos de vida libre en el ambiente de transición del lago Varano (sur de Italia)Este estudio documenta por primera vez la composición taxonómica de la comunidad de nematodos y el número de especies de nematodos de vida libre presentes en el lago Varano, al sur del mar Adriático (Italia). La comunidad de nematodos estaba compuesta principalmente por especies típicas de los sedimentos finos predominantes en ambientes de transición (TE). En conjunto, se registró un elevado número de especies de nematodos (55) pertenecientes a 36 géneros de 17 familias. Estos valores son comparables en gran medida a los registrados en otros TE italianos, pero inferiores a los registrados en otros sistemas de aguas salobres europeos, probablemente en relación con el bajo nivel de salinidad del lago Varano. Se identificaron cuarenta taxones a nivel de especie, lo que incrementa el número de especies conocidas de nematodos marinos en las costas italianas de 443 a 463, en la cuenca del Adriático de 310 a 313 y en el sur del mar Adriático de 37 a 77. Considerando la importancia de este fílum para la valoración de la calidad ecológica y la gran vulnerabilidad de los ecosistemas del mar Adriático, debería planificarse la intensificación de las acciones de muestreo, especialmente en la parte centro-meridional de la cuenca. Un plan de este tipo proporcionaría nuevos conocimientos de la biogeografía de uno de los componentes más importantes del bentos y podría aportar nueva información acerca de los efectos del calentamiento climático en el mar Adriático

    Assessment of the ecological quality (EcoQ) of the Venice lagoon usingthe structure and biodiversity of the meiofaunal assemblages

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    partially_open3noTransitional Environments (TEs) have been deeply modified to meet human requirements, and for thisreason are currently ranked among the most endangered aquatic ecosystems. The Adriatic basin hosts alarge number of TEs of which the Lagoon of Venice is the largest one, but information on its meiofauna arevery dated or focused to localized areas. The present study is the first to document the spatial distributionof meiofauna in the whole Venice lagoon. Furthermore, the health status of the TE of Venice has beenassessed by means of several faunal parameters (richness, diversity indices, structure of the entire meio-faunal assemblage and only rare taxa). All the univariate meiofaunal parameters (i.e. richness, diversityindices, Ne:Co ratio) were consistent in highlighting the worst ecological quality of the Porto Margheradistrict. Instead, the structure of the entire meiofaunal assemblage as well as that of rare taxa seemed todetect variations not directly related to pollution and likely due to the different hydrodynamic conditionsof Lido and Malamocco inlets. On the basis of our results, we have also critically discussed the usefulnessof the various faunal parameters in the monitoring assessment of the TEs.openSemprucci, Federica; Balsamo, Maria; Sandulli, RobertoSemprucci, Federica; Balsamo, Maria; Sandulli, Robert

    Hybrid Storage System Control Strategy for All-Electric Powered Ships

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    Abstract In marine applications all-electric propulsion systems are employed on surface ships that are subjected to particular constraints, generally due to environmental restrictions. The technological advancement of electrochemical batteries, which are today characterized by higher capacity and efficiency, has widened their fields of application, although these storage systems require an accurate design to limit their initial and maintenance costs. In order to reduce battery charge and discharge peak currents, supercapacitor modules are generally adopted with the aim to extend batteries expected life. The proper management of energy fluxes within the hybrid architecture, and in particular among batteries, capacitors and loads requires a specific control, called EMS – Energy Management Strategy. In this paper, a novel EMS, based on constrained minimization problem, is proposed and verified with reference to a case study of a waterbus operating in restricted waterways on different routes. The procedure is based on a preliminary solution of an off-line optimization with respect to a known mission profile. Hence, a real-time control strategy is properly evaluated, in order to guarantee robustness against the unavoidable uncertainties, which occur during the operating conditions. In the last part of the paper, a numerical application is presented with the purpose to emphasize the feasibility of the proposal

    Marine dual-fuel engines power smart management by hybrid turbocharging systems

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    The performance of a marine dual-fuel engine, equipped with an innovative hybrid turbocharger producing electric power to satisfy part of the ship’s electric load, is presented by a simulation comparison with the traditional turbocharging technology. The two distinct fuel types, combined with the hybrid turbocharger, involve a substantial change in the engine control modes, resulting in more flexible and efficient power management. Therefore, the investigation requires a numerical analysis depending on the engine load variation, in both fuelling modes, to highlight different behaviours. In detail, a dual-fuel engine simulation model is validated for a particular application in order to perform a complete comparison, reported in tabular and graphical form, between the two examined turbocharging solutions. The simulation analysis is presented in terms of the engine working data and overall energy conversion efficiency

    The Ampullae of the Inner Ear in the Lizard Podarcis S. Sicula. Ultrastructural Aspects

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    The inner ear ampullae of the lizard Podarcis s. sicula were studied to determine better the ultrastructure of ampullar epithelial cells. Our study confirmed that the ampullae of the membranous labyrinth of this lizard are similar to those of other vertebrates in their ultrastructural aspect. Moreover, our observations revealed a special type of dark cells, restricted to a small area of the crista. They appeared similar to type II sensory cells and showed a dark, finely granular cytoplasm, containing numerous mitochondria and ribosomes, extensive Golgi apparatus and abundant glycogen. The morphology of these cells suggests that they may be special sensory cells, or different stages of sensory cells, probably implied in the crista cell turn-over described for some vertebrate groups

    Validation of an Emission Model for a Marine Diesel Engine with Data from Sea Operations

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    In this study, a model is developed to simulate the dynamics of an internal combustion engine, and it is calibrated and validated against reliable experimental data, making it a tool that can effectively be adopted to conduct emission predictions. In this work, the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine, a four-stroke engine used in the maritime field. Results from the bench tests are used for the calibration of the model. Finally, the calibration of the model and its validation with full-scale data measured at sea are presented. The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions, which are compared with similar results obtained with emission factors. The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7% on power, torque, and consumption. The model provides encouraging results, suggesting further applications, such as in the study on transient conditions, coupling of the engine model with the ship model for a complete simulation of the operating conditions, and optimization studies on consumption and emissions. The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work

    Particle size distributions by laser diffraction: sensitivity of granular matter strength to analytical operating procedures

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    We tested laser diffraction particle size analysis in poorly coherent carbonate platform cataclastic breccias and unfaulted quartz-rich eolian sands, representing low- and high-strength granular materials, respectively. We used two different instruments with different sample dispersion and pumping systems and several wet analytical procedures that included different pump speeds, measurement precision tests with and without sample ultrasonication, and different dispersant liquids. Results of our work indicate that high strength material is not strongly affected by analytical operating procedures, whereas low strength materials are very sensitive to the pump speed, ultrasonication intensity, and measurement run time. To reduce such a data variability, we propose a workflow of analytical tests preliminary to the set up of the most appropriate SOP

    Recurrent PET FDG Uptake after Sequential Chemotherapy and Radiation Therapy for DLBCL of the Tibia: A Case Report and Review of the Literature

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    The aim of this paper is to report on the challenges associated with identifying disease recurrence following combined modality therapy (CMT) for primary lymphoma of the tibia in which an intramedullary nail has been placed. A patient with primary bone lymphoma (PBL) was treated with CMT (chemotherapy and radiation therapy). After a complete response, he has been followed for eighteen months by physical exam and radiographic imaging. Despite persistent increased tracer accumulation at the original site, he has no proven recurrence. Literature review showed a small number of retrospective, single institution reviews detailing clinical experience and expected outcome in patients treated with PBL limited to one bony site of disease. PBL presents a treatment challenge, particularly when a weight-bearing long bone is diffusely involved and followup is complicated after placement of stabilizing hardware. Close coordination of the oncology team and diagnostic radiology is required to ensure optimal outcome

    New Data on Reproductive System and Spermatozoa Confirm Macrodasys as a Model in Comparative Reproductive Analysis in Macrodasyida (Gastrotricha)

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    Gastrotricha Macrodasyida, aquatic worms, are primarily hermaphrodites with internal cross-fertilization and indirect sperm transfer. Insightful information on this matter dates to 1978 and derives from an illuminating work focused on two Macrodasys species. The role as a “model” of this taxon clashes, however, with the relative paucity of data concerning the ultrastructure of the accessory organs involved in the sperm transfer. Therefore, we have undertaken a new study on three additional species of Macrodasys focusing on the frontal and caudal organs and also on the spermatozoa. Our observations confirmed the structural plan of the reproductive system reported for the genus, but found some differences concerning the accessory reproductive organs. Most importantly, we found spermatozoa inside the caudal organ of several single specimens, suggestive of a more plausible hypothesis about sperm transfer modality in Macrodasys. In the spermatozoa, the position of the mitochondrion outside rather than inside the nucleus has been confirmed as a major difference between the spermatozoa of Macrodasys species and those of the other Macrodasyida. We suggest that the peculiar structure of the mature spermatozoon of Macrodasys could derive from an incomplete process of spermatogenesis and hence it would be useful to infer phylogenetic alliances
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