2,117 research outputs found
Synanthropic-dominated biomass in an insular landbird assemblage
The effect of anthropization on sedentary landbirds occurring in late summer on a small Mediterranean island (San Pietro, SW Sardinia) has been studied comparing abundance and biomass among different ecological guilds. The two specialized insular guilds (Mediterranean warblers and rocky cliff species) represent about half of the total individual abundance (47%) but only 16% in terms of biomass. Although almost all the surface of the island is covered by Mediterranean scrub (maquis), Mediterranean warblers were not as dominant as the guild of strictly synanthropic species. This latter guild was the most represented in frequency both for abundance and biomass. I hypothesize that (i) here the anthropization could be considered a locally relevant process disrupting the resource flow and lowering the trophic level and (ii) the dominance of synanthropic birds in terms of biomass could be a general phenomenon extended to a large set of Mediterranean islands. The three most abundant synanthropic species, linked to highly disturbed habitats, showed a larger body mass when compared to specialized species as Mediterranean warblers: when applying the Abundance/Biomass Comparison (ABC), an early cumulating biomass curve was observed, partially overlapping with abundance curve. This pattern did not match with the classic predictions for the ABC model (i.e., species with higher biomass are typical of undisturbed assemblage) and could be wrongly interpreted. Therefore, I suggest that the ABC assumptions are not universal but limited only to assemblages where high body mass species coincide to species of a higher trophic level
Toward a new generation of effective problem solvers and project-oriented applied ecologists
Abstract. In an era of environmental crises, conservation and management strategies
need a new generation of applied ecologists. Here, we stimulate the
next-generation applied ecologists to acquire a pragmatic mentality of
problems solvers in real contexts, using the wide arsenal of concepts,
approaches and techniques available in the project management (PM) arena using a
road map based on the main steps of conservation project cycle. The
acquisition of the conceptual and operational framework of PM can allow the
next-generation applied ecologists to take on a more important role in
nature conservation strategies: from data samplers, analyzers and
interpreters to suppliers of solutions and decisions driving changes in
species' targets inhabiting real contexts. Since the high number of applied
ecologists, this change in approach (from analytical to operational) could
make the difference in conservation science. We also provided, as a
conceptual framework, a set of suggestions and approaches useful to
facilitate this change
Probing the formation history of the nuclear star cluster at the Galactic Centre with millisecond pulsars
The origin of the Nuclear Star Cluster in the centre of our Galaxy is still
unknown. One possibility is that it formed after the disruption of stellar
clusters that spiralled into the Galactic Centre due to dynamical friction. We
trace the formation of the Nuclear Star Cluster around the central black hole,
using state-of-the-art N-body simulations, and follow the dynamics of the
neutron stars born in the clusters. We then estimate the number of Millisecond
Pulsars (MSPs) that are released in the Nuclear Star Cluster, during its
formation. The assembly and tidal dismemberment of globular clusters lead to a
population of MSPs distributed over a radius of about 20 pc, with a peak near 3
pc. No clustering is found on the sub-parsec scale. We simulate the
detectability of this population with future radio telescopes like the MeerKAT
radio telescope and SKA1, and find that about of order ten MSPs can be observed
over this large volume, with a paucity of MSPs within the central parsec. This
helps discriminating this scenario from the in-situ formation model for the
Nuclear Star Cluster that would predict an over abundance of MSPs closer to the
black hole. We then discuss the potential contribution of our MSP population to
the gamma-ray excess at the Galactic Centre.Comment: 11 pages, 8 figures, accepted for publication in MNRA
ITCZ shift and extratropical teleconnections drive ENSO response to volcanic eruptions
The mechanisms through which volcanic eruptions affect the El Niño-Southern Oscillation (ENSO) state are still controversial. Previous studies have invoked direct radiative forcing, an ocean dynamical thermostat (ODT) mechanism, and shifts of the Intertropical Convergence Zone (ITCZ), among others, to explain the ENSO response to tropical eruptions. Here, these mechanisms are tested using ensemble simulations with an Earth system model in which volcanic aerosols from a Tambora-like eruption are confined either in the Northern or the Southern Hemisphere. We show that the primary drivers of the ENSO response are the shifts of the ITCZ together with extratropical circulation changes, which affect the tropics; the ODT mechanism does not operate in our simulations. Our study highlights the importance of initial conditions in the ENSO response to tropical volcanic eruptions and provides explanations for the predominance of posteruption El Niño events and for the occasional posteruption La Niña in observations and reconstructions
Accuracy of MRI skeletal age estimation for subjects 12–19. Potential use for subjects of unknown age
In forensic practice, there is a growing need for accurate methods of age estimation, especially in the cases of young individuals of unknown age. Age can be estimated through somatic features that are universally considered associated with chronological age. Unfortunately, these features do not always coincide with the real chronological age: for these reasons that age determination is often very difficult. Our aim is to evaluate accuracy of skeletal age estimation using Tomei's MRI method in subjects between 12 and 19 years old for forensic purposes.
Two investigators analyzed MRI images of the left hand and wrist of 77 male and 74 female caucasian subjects, without chronic diseases or developmental disorders, whose age ranged from 12 to 19 years. Skeletal maturation was determined by two operators, who analyzed all MRI images separately, in blinded fashion to the chronological age. Inter-rater agreement was measured with Pearson (R (2)) coefficient. One of the examiners repeated the evaluation after 6 months, and intraobserver variation was analyzed. Bland-Altman plots were used to determine mean differences between skeletal and chronological age.
Inter-rater agreement Pearson coefficient showed a good linear correlation, respectively, 0.98 and 0.97 in males and females. Bland-Altman analysis demonstrated that the differences between chronological and skeletal age are not significant. Spearman's correlation coefficient showed good correlation between skeletal and chronological age both in females (R (2) = 0.96) and in males (R (2) = 0.94).
Our results show that MRI skeletal age is a reproducible method and has good correlation with chronological age
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