Long-Distance animal migrations in the oceanic environment: Orientation and navigation correlates

A large variety of marine animals migrate in the oceanic environment, sometimes aiming at specific targets such as oceanic islands or offshore productive areas. Thanks to recent technological developments, various techniques are available to track marine migrants, even when they move in remote or inhospitable areas. The paper reviews the main findings obtained by tracking marine animals during migratory travels extending over large distances, with a special attention to the orientation and navigation aspects of these phenomena. Long-distance movements have now been recorded in many marine vertebrates, revealing astonishing performances such as individual fidelity to specific sites and basin-wide movements directed towards these locations. Seabirds cover the longest distances, sometimes undertaking interhemispheric flights, but transoceanic migrations are also the rule in pelagic fish, turtles, pinnipeds, and whales. Some features of these journeys call for the involvement of efficient orientation and navigational abilities, but little evidence is available in this respect. Oceanic migrants most likely rely on biological compasses to maintain a direction in the open sea, and displacement experiments have provided evidence for an ability of seabirds and turtles to rely on position-fixing mechanisms, possibly involving magnetic and/or olfactory cues, although simpler navigational systems are not to be excluded

STATUS DELLA VITAMINA D NELLA MALATTIA RENALE CRONICA ED EFFETTO DELLA SUPPLEMENTAZIONE CON COLECALCIFEROLO

Questo studio investiga i fattori legati all' ipovitaminosi D, in una popolazione di 405 pazienti con CKD dagli stadi 2 a 4, che vivono in Italia e che sono seguiti presso La Nefrologia della AOUP . Nello studio viene anche valutato un sottogruppo di 100 pazienti con ipovitaminosi D, che hanno ricevuto un trattamento per 12 mesi con colecalciferolo alla dose 10000 unità una volta alla settimana La carenza di vitamina D, ovvero valori al di sotto dei 20 ng/ml, sono stati ritrovati in 269 pazienti (66,4 %), mentre uno stato di insufficienza di vitamina D, ovvero valori tra 21 e 30 ng/ml (oggi viene considerato 30ng/ml il valore necessario di vitamina D per parlare di quantità sufficiente ), è stato ritrovato in 67 pazienti (16,5%). In pazienti diabetici il deficit della 25(OH)vitD raggiungeva l' 80% dei casi. Nei pazienti con età superiore ai 65 anni il deficit raggiungeva l' 89 % dei soggetti. I livelli di 25(OH)vitD erano negativamente correlati a età, PTH, proteinuria, Charlson index; al contrario, una relazione positiva era emersa con i valori di emoglobina. L’ analisi di regressione multipla mostrava che l' età e il PTH sono indipendentemente associati con i livelli di vitamina D, mentre non compariva una relazione tra i livelli della 25(OH)vitD e la funzione renale. I livelli sierici della 25(OH)vitD non differivano tra soggetti con dieta libera e soggetti che facevano una dieta a basso contenuto di fosfati e proteine. Dodici mesi di terapia con 10000 unità di colecalciferolo una volta alla settimana aumentavano i valori di idrossivitamina D e abbassavano i livelli sierici di PTH. In sintesi, lo stato di carenza e insufficienza di vitamina D è presente nella maggior parte dei soggetti (83%) con CKD in Italia; i livelli della 25 (OH)vitD sono maggiormente legati ai livelli sierici di PTH e all' età avanzata piuttosto che ad altri fattori. L' assunzione orale di colecalciferolo migliora i livelli della 25 (OH)vitD e riduce i livelli sierici di PTH, quindi dovrebbe sempre essere raccomandata nei pazienti con CKD e ipovitaminosi D, o quando non fosse disponibile il dosaggio della 25(OH)vit

Studio di riempimenti per la rimozione di CO2 da fumi di combustione

Sono state effettuate prove sperimentali atte al calcolo del coefficiente di scambio di materia lato liquido attraverso un processo di desorbimento di CO2 da acqua in aria. Liquid film mass transfer coefficient has been investigated with desorbption of CO2 from water to air

An analytical model for the resonance frequency of square perforated Lamé-mode resonators

In this work, simple analytical models based on the concept of an equivalent material are used to describe the mechanical behavior of resonators perforated by a regular array of square holes, a common occurrence in several MEMS devices and sensors. This description is applied to the determination of the resonance frequency of Lamé-mode square resonators, which are frequently pursued as high-Q MEMS resonators. The models predictions are compared with FEM simulations and experimental data both from the literature and from measurements obtained by the authors on thick SOI MEMS resonators. The models predictions are in good accordance both with FEM results and with experimental data

A Transmission Line Model for the Calculation of Phononic Band Gaps in Perforated Mems Structures

AbstractIn this paper an acoustic transmission line model for the calculation of phononic band gaps is presented. We study the propagation of longitudinal waves in thin, rectangular perforated rods. We show that the 1D nature of the rod vibrations allows the modeling of the system by a series of acoustic transmission lines with different characteristic impedance, where the perforated section is modeled as an equivalent filled material with Young's modulus and mass density depending from the size of the holes. Once this model is defined, the derivation of the transmission matrix and transmission coefficient (in matching conditions) of the entire rod is straightforward by using the classical transmission line theory. Finally, the phononic band gap predicted by this model is verified by means of an ANSYS harmonic analysis

Movement patterns of marine turtles in the Mediterranean Sea: a review

Understanding the at-sea spatial behaviour of sea turtles is a priority for their conservation. In the present paper, the current information on the distribution and movement patterns of the two species breeding in the Mediterranean, the loggerhead and the green turtle, is reviewed, focusing mainly on the 195 published routes of satellite-tracked turtles. A satisfactory level of knowledge about adults’ migrations and other movements is reached only for loggerheads breeding at Zakynthos Island, Greece, and for green and loggerhead females nesting in Cyprus, while studies at foraging grounds are limited to loggerheads in the western and central parts of the basin. Adult males and females mostly show quite uniform post-breeding migratory patterns, typically moving towards individually specific neritic foraging grounds. A much higher variability is shown by loggerhead juveniles, which is probably associated with differences in their spatial behaviour while in oceanic or neritic waters. Evidence of seasonal migrations driven by lower temperatures in winter is available only for adult and juvenile loggerheads frequenting the two northernmost parts of the basin, i.e. the Ligurian and the northern Adriatic Sea. Current knowledge gaps and priorities for further research in the Mediterranean are discussed