Search results for " migration."
showing 10 items of 718 documents
Reply to Douka et al: Critical evaluation of the Ksâr 'Akil chronologies
2015
Our paper (1) proposes a new chronology for Ksâr 'Akil based on 16 accelerator mass spectrometry (AMS) determinations on shells. To minimize the possibility of dating diagenetically compromised samples, we conducted amino acid racemization analyses on the intracrystalline proteins, oxygen isotope analysis, and geochemical characterization of all dated shells. Our calibrated radiocarbon ages fit well with existing Levantine chronologies, but are up to 4,000 y older than Douka et al.’s (2). Our paper explores several possibilities for this difference, whereas Douka et al. (3) provide alternative explanations. They accept our radiocarbon ages as correct but question our sample selection and Ba…
The generation of oligodendroglial cells is preserved in the rostral migratory stream during aging
2013
The subventricular zone (SVZ) is the largest source of newly generated cells in the adult mammalian brain. SVZ-derived neuroblasts migrate via the rostral migratory stream (RMS) to the olfactory bulb (OB), where they differentiate into mature neurons. Additionally, a small proportion of SVZ-derived cells contribute to the generation of myelinating oligodendrocytes. The production of new cells in the SVZ decreases during aging, affecting the incorporation of new neurons into the OB. However, the age-related changes that occur across the RMS are not fully understood. In this study we evaluate how aging affects the cellular organization of migrating neuroblast chains, the proliferation, and th…
REVISIONE PRELIMINARE DELLA BIODIVERSITÀ ENTOMOLOGICA DELL’ISOLA DI LAMPEDUSA (SICILIA - ITALIA) PRELIMINARY REVISION OF ENTOMOLOGICAL BIODIVERSITY I…
2013
Lampedusa è un'isola appartenente all'arcipelago delle Pelagie, che è particolarmente interessante per l'aspetto faunistico, in quanto crocevia tra la fauna Europea e Africana. Gli insetti, per la loro abbondanza e diversità in natura, rappresentano una classe nel regno animale particolarmente utile per studiare la biodiversità e i fenomeni di migrazione o emigrazione delle specie, e per valutare inoltre eventuali cambiamenti climatici. Allo stato attuale i dati sull'entomofauna non sono organici e sono riportati in modo spesso frammentario, e la check-list più completa disponibile è datata 1995, quasi venti anni fa. Lo scopo di questo lavoro è stato quello di impiegare nuove tecniche di ri…
Limited potential for bird migration to disperse plants to cooler latitudes
2021
Climate change is forcing the redistribution of life on Earth at an unprecedented velocity1,2. Migratory birds are thought to help plants to track climate change through long-distance seed dispersal3,4. However, seeds may be consistently dispersed towards cooler or warmer latitudes depending on whether the fruiting period of a plant species coincides with northward or southward migrations. Here we assess the potential of plant communities to keep pace with climate change through long-distance seed dispersal by migratory birds. To do so, we combine phenological and migration information with data on 949 seed-dispersal interactions between 46 bird and 81 plant species from 13 woodland communi…
Diel feeding habits of juveniles of Mullus surmuletus (Linneo, 1758) in the lagoon of the Stagnone di Marsala (Western Sicily, Italy)
1999
Diet composition, feeding rhythm, gastric evacuation rate and daily ration were investigated in juvenile Mulhis surmuletus (Linneo, 1758). Fish were collected in the lagoon of the Stagnone di Marsala in western Sicily, in July 1995, during a 24 h sampling period. Copepoda, Polychaeta, Amphipoda and Tanaidacea were shown to be the most frequent prey items. The feeding index values showed two different daily feeding times. A unimodal trend in the daily rhythm of food consumption was derived, with a peak in feeding between 1200 and 2000 h. Gastric evacuation in juvenile M. surmuletus is best described by an exponential model, with a gastric evacuation rate R = 0.66 g h-1 (r = 0.88) (T = 24.45 …
Effect of salinity and temperature on feeding physiology and scope for growth of an invasive species (Brachidontes pharaonis - MOLLUSCA: BIVALVIA) wi…
2008
Abstract The Indo-Pacific mytilid Brachidontes pharaonis (Bivalvia, Fischer 1870) offers an excellent model for the study of “Lessepsian migration” and the successive colonization at new Mediterranean locations. This species in out competing indigenous bivalves is particularly well adapted to Mediterranean conditions and this is likely due to biological characteristics and physio-ecological plasticity. In the present paper, we report on clearance rate (CR), respiration rate (RR) and Scope for Growth (SFG) of B. pharaonis collected from a Western Sicilian pond (Southern Tyrrhenian, MED). Physiological variables were determined in response to a range of temperatures from 11 ° to 20 °C and a b…
Year-round variation in the isotopic niche of Scopoli's shearwater (Calonectris diomedea) breeding in contrasting sea regions of the Mediterranean Sea
2022
Top marine predators are key components of marine food webs. Among them, long-distance migratory seabirds, which travel across different marine ecosystems over the year, may experience important year-round changes in terms of oceanographic conditions and availability of trophic resources. We tested whether this was the case in the Scopoli’s shearwater (Calonectris diomedea), a trans-equatorial migrant and top predator, by sampling birds breeding in three environmentally different regions of the Mediterranean Sea. The analysis of positional data and stable isotopes (δ13 C and δ15N) of target feathers revealed that birds from the three regions were spatially segregated during the breeding per…
HUMAN PEOPLING OF SICILY DURING QUATERNARY
2015
ABSTRACT The early human peopling of Sicily and Western Mediterranean shores is one of the debated topic in the archaeological and anthropological literature over the twentieth century. This discussion involves not only the specific issue of the peopling of the continental island, but fundamentally the reconstruction of human migration routes and dispersals across the Mediterranean area during Early and Middle Pleistocene. Even if the common route of faunal and human movement is considered from North, and relative to the Messina strait crossing, several authors, on the base of archaeological evidences, hypothesized an early peopling and an African provenance through the Sicilian Channel. Th…
WIN modulates osteosarcoma MG63 cell migration by inhibiting MMPs activity and adjusting intra- and extra-cellular SPARC differential expression
2014
Invasion of cancer cells into surrounding tissue is an initial step in tumor metastasis. This event, which requires migration of cancer cells and attachment to extracellular matrix (ECM), is regulated by elements of the local microenvironment, including ECM architecture. After having demonstrated the ability of the synthetic cannabinoid WIN55,512 to induce osteosarcoma MG63 cell death (1), we studied the effects of WIN on MG63 cell migration. Wound healing assay was performed to measure the ability of cells to migrate and fill the gap obtained by physical disruption of cell monolayer (2). We observed a significant delay in wound closure in 5 M WIN treated cells compared to untreated cells …
Teoria e pratica nel progetto di architettura. Quali contenuti?
2016
Il progetto di architettura, attraverso la sua opera di modificazione, intende definire tutte quelle relazioni fondamentali che si instaurano tra natura e artificio, tra luogo e individuo. La realtà contemporanea è costituita sempre più da città, frutto di pezzi diversi, che non sempre dialogano fra loro, e che si ritrovano a fare i conti non soltanto attraverso le connessioni fra i diversi frammenti di architettura, ma anche e soprattutto con i nuovi aspetti sociali che scaturiscono dai numerosi fenomeni migratori. Lo scritto intende, infatti, attraverso le ricerche didattiche svolte all'interno del Dipartimento di Architettura sul tema della multiculturalità, indagare il fenomeno migrator…