1,845 research outputs found
A Temporal Analysis of the Euphausiid Assemblage in the Gulf of Mexico after the Deepwater Horizon Oil Spill, with Notes on Seasonal Reproduction
This thesis presents the results of the first multi-year study on the euphausiid assemblage in the vicinity of the Deepwater Horizon oil spill (DWHOS), covering depths down to 1000 m. There are no data on the euphausiid assemblage from this region prior to the oil spill; therefore, the data in this study were analyzed with respect to year (samples collected in 2011 vs. those collected between 2015 – 2016), and season (May vs. August) to determine if any trends were present. These results presented here show a statistically significant decrease in both abundance and biomass between 2011 and 2015 – 2016, indicating that the assemblage has been declining since 2011, along with a continued decline from May 2016 to May 2017. Seasonal effects were also present, as abundance and biomass were statistically higher in May than in August in both 2011 and 2016. In addition, the percentage of gravid females of the grouped species, Nematoscelis atlantica/microps, was also higher in May for both years, but only statistically significant in 2016. This seasonal variability may possibly be linked to food availability as a result of seasonal phytoplankton blooms. The information presented here will act as a reference point for future studies in the Gulf of Mexico (GOM), to aid in understanding how the euphausiid assemblage responds to anthropogenic events
Non \ue8 pi\uf9 quella di una volta. La mafia e le attivit\ue0 estorsive in Sicilia
Il volume presenta i risultati di una ricerca volta alla descrizione dei fenomeni estorsivi e della loro intensit\ue0 in Sicilia, raccontando, sulla base di appositi parametri oggettivi e di valutazioni soggettive degli esponenti del mondo delle associazioni e delle forze dell\u2019ordine, le aree pi\uf9 esposte, quelle meno esposte, quelle dove i fenomeni hanno una rilevanza residuale, in una fase in cui i sodalizi mafiosi sono sempre pi\uf9 pressati dall\u2019azione di contrasto. Per raggiungere questo obiettivo ci si \ue8 avvalsi di strumenti qualitativi e dati quantitativi, approfondendo l\u2019analisi delle trasformazioni delle condotte estorsive durante la crisi, concentrandosi in modo specifico su casi emersi nell\u2019ambito di recenti inchieste giudiziarie. Il libro ricostruisce anche la prospettiva e le difficolt\ue0 di alcuni imprenditori siciliani che, dopo aver pagato il pizzo, hanno scelto di denunciare i propri estorsori e di collaborare con le istituzioni
Le scienze sociali e la Terza missione delle università
Alcune riflessioni sull'impatto delle scienze sociali sulla Terza Missione delle Universit
A weakly compressible hybridizable discontinuous Galerkin formulation for fluid-structure interaction problems
A scheme for the solution of fluid-structure interaction (FSI) problems with
weakly compressible flows is proposed in this work. A novel hybridizable
discontinuous Galerkin (HDG) method is derived for the discretization of the
fluid equations, while the standard continuous Galerkin (CG) approach is
adopted for the structural problem. The chosen HDG solver combines robustness
of discontinuous Galerkin (DG) approaches in advection-dominated flows with
higher order accuracy and efficient implementations. Two coupling strategies
are examined in this contribution, namely a partitioned Dirichlet-Neumann
scheme in the context of hybrid HDG-CG discretizations and a monolithic
approach based on Nitsche's method, exploiting the definition of the numerical
flux and the trace of the solution to impose the coupling conditions. Numerical
experiments show optimal convergence of the HDG and CG primal and mixed
variables and superconvergence of the postprocessed fluid velocity. The
robustness and the efficiency of the proposed weakly compressible formulation,
in comparison to a fully incompressible one, are also highlighted on a
selection of two and three dimensional FSI benchmark problems.Comment: 49 pages, 20 figures, 2 table
Citizenship as an active subject for recovery of the heritage of social housing in Modern Movement at Valencian Community, Spain
[EN] Given the complexity of the heritage project and current urban regeneration processes, citizen participation, as central point for good governance and sustainability, is of vital importance. Contributing to the knowledge of architecture of social housing in the Modern Movement requires an approach to social reality of its residents, identifying and recognizing the living heritage values from social perception and practice. That is why accession of residents as active subjects in this process is essential, but also for subsequent elaboration of strategies for revitalization, updating and sustainable recovery, environmental and social, which will not affect the preservation of existing values in this historical-cultural heritage of our cities. Likewise, participatory processes in this field of work have, at the same time, a pedagogical task, in the way of publicizing values of modern heritage in order to achieve its recognition and appreciation by society. This paper presents the approach from field of citizen participation and potential participatory methodologies that guide the research work, specifically, within the framework of the Momovivso research project, focused on possibilities of recovery and conservation of social housing of the Modern Movement in the Valencian Community, Spain.This work is carried out within the Momovivso Research Project, funded by the Programme for the promotion of scientific research, technological development and innovation in the Valencian Community (AICO/2021), File AICO/2021/253.Sosa Espinosa, A.; La Spina, V.; Navarro Camallonga, P.; Songel González, J. (2023). Citizenship as an active subject for recovery of the heritage of social housing in Modern Movement at Valencian Community, Spain. Editorial Universitat Politècnica de València. 536-544. https://doi.org/10.4995/VIBRArch2022.2022.1518753654
The role of syn-eruptive vesiculation on explosive basaltic activity at Mt. Etna, Italy
We investigated the dynamics of explosive activity at Mt. Etna between 31 August and 15 December 2006 by combining vesicle studies in the erupted products with measurements of the gas composition at the active, summit crater. The analysed scoria clasts present large, connected vesicles with complex shapes and smaller, isolated, spherical vesicles, the content of which increases in scoriae from the most explosive events. Gas geochemistry reports CO2/SO2 and SO2/HCl ratios supporting a deep-derived gas phase for fire-fountain activity. By integrating results from scoria vesiculation and gas analysis we find that the highest energy episodes of Mt. Etna activity in 2006 were driven by a previously accumulated CO2-rich gas phase but we highlight the lesser role of syn-eruptive vesicle nucleation driven by water exsolution during ascent. We conclude that syn-eruptive vesiculation is a common process in Etnean magmas that may promote a deeper conduit magma fragmentation and increase ash formation
Detection of microplastic contamination in comercial insect meals.
Background: Escalating global plastic production, expected to reach 34,000 million tons
by 2050, poses a significant threat to human and environmental well-being, particularly in aquatic
ecosystems. Microplastics (MP) and nanoplastics (NP), which originate from the degradation of plastics, are of concern due to their potential bioaccumulation and uptake of pollutants. This study addresses identification methods and focuses on insect meal, a raw material for aquaculture feed.
Methods: By using different techniques, the study was able to detect MP and NP in insect meal
samples. Chemical digestion with KOH at 60 ◦C efficiently removed organic matter without affecting the synthetic polymer polyethylene (PE). Filtration, confocal Raman microscopy, SEM, and TEM
were used for comprehensive analysis, and integrity tests on PE films were performed using Ramanand FTIR spectroscopy. The results showed the presence of PE microplastic particles in the insect meal, which was confirmed by correlative Raman and SEM mapping on a positively charged surface.
In addition, the increased resolution of the Raman microscope identified submicrometric PE NP (800 nm). Transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX) confirmed plastic-like structures in the insect meal, highlighting the presence of PE plastics characterized by irregular shapes and some agglomeration. The higher carbon concentration in the EDX analysis supported the plastic nature, which was also confirmed by Raman spectroscopy.
Conclusions: The study provides a robust method for the detection of MP and NP in insect meal and provides valuable insight into the possible presence of plastics in insect-based aquafeeds. The combination of different analytical methods increases the reliability of the results and sets the for future investigations that could focus on the quantification of NP and the assessment of their potential environmental impact
New insights into volcanic processes at Stromboli from Cerberus, a remote-controlled open-path FTIR scanner system
The ordinary, low intensity, activity of Stromboli volcano is sporadically interrupted by more energetic events termed, depending on their intensity, “major explosions” and “paroxysms”. These short-lived energetic episodes represent a potential risk to visitors to the highly accessible summit of Stromboli. Observations made at Stromboli over the last decade have shown that the composition of gas emitted from the summit craters may change prior to such explosions, allowing the possibility that such changes may be used to forecast these potentially dangerous events.
In 2008 we installed a novel, remote-controlled, open-path FTIR scanning system called Cerberus at the summit of Stromboli, with the objective of measuring gas compositions from individual vents within the summit crater terrace of the volcano with high temporal resolution and for extended periods. In this work we report the first results from the Cerberus system, collected in August-September 2009, November 2009 and May-June 2010.
We find significant, fairly consistent, intra-crater variability for CO2/SO2 and H2O/CO2 ratios, and relatively homogeneous SO2/HCl ratios. In general, the southwest crater is richest in CO2, and the northeast crater poorest, while the central crater is richest in H2O. It thus appears that during the measurement period the southwest crater had a somewhat more direct connection to a primary, deep degassing system; whilst the central and northeast craters reflect a slightly more secondary degassing nature, with a supplementary, shallow H2O source for the central crater, probably related to puffing activity. Such water-rich emissions from the central crater can account for the lower crystal content of its eruption products, and emphasise the role of continual magma supply to the shallowest levels of Stromboli's plumbing system.
Our observations of heterogeneous crater gas emissions and high H2O/CO2 ratios do not agree with models of CO2-flushing, and we show that simple depressurisation during magma ascent to the surface is a more likely model for H2O loss at Stromboli. We highlight that alternative explanations other than CO2 flushing are required to explain distributions of H2O and CO2 amounts dissolved in melt inclusions.
We detected fairly systematic increases in CO2/SO2 ratio some weeks prior to major explosions, and some evidence of a decrease in this ratio in the days immediately preceding the explosions, with periods of low, stable CO2/SO2 ratios between explosions otherwise. Our measurements, therefore, confirm the medium term (~ weeks) precursory increases previously observed with MultiGas instruments, and, in addition, reveal new, short-term precursory decreases in CO2/SO2 ratios. immediately prior to the major explosions. Such patterns, if shown to be systematic, may be of great utility for hazard management at Stromboli's summit.
Our results suggest that intra-crater CO2/SO2 variability may produce short-term peaks and troughs in CO2/SO2 time series measured with in-situ MultiGas instruments, due simply to variations in wind direction
The role of syn-eruptive vesiculation on explosive basaltic activity at Mt. Etna, Italy
We investigated the dynamics of explosive activity at Mt. Etna between 31 August and 14 December 2006 by combining vesicle studies in the erupted products with measurements of the gas composition at the active, summit crater. The analysed scoria clasts present large, connected vesicles with complex shapes and smaller, isolated, spherical vesicles, the content of which increases in scoriae from the most explosive events. Gas geochemistry reports CO2/SO2 and SO2/HCl ratios supporting a deep-derived gas phase for fire-fountain activity. By integrating results from scoria vesiculation and gas analysis we find that the highest energy episodes of Mt. Etna activity in 2006 were driven by a previously accumulated CO2-rich gas phase but we highlight the lesser role of syn-eruptive vesicle nucleation driven by water exsolution during ascent. We conclude that syn-eruptive vesiculation is a common process in Etnean magmas that may promote a deeper conduit magma fragmentation and increase ash formatio
Multiparametric study of the February-April 2013 paroxysmal phase of Mt. Etna New South-East crater
Between January 2011 and April 2013, Mt. Etna's eruptive activity consisted of episodic intracrater strombolian explosions and paroxysms from Bocca Nuova, Voragine, and the New South-East (NSEC) summit craters, respectively. Eruptions from NSEC consisted of initial increasing strombolian activity and lava flow output, passing to short-lasting lava fountaining. In this study we present seismic, infrasound, radiometric, plume SO2 and HCl fluxes and geodetic data collected by the INGV monitoring system between May 2012 and April 2013. The multiparametric approach enabled characterization of NSEC eruptive activity at both daily and monthly time scales and tracking of magma movement within Mt. Etna's plumbing system. While seismic, infrasound and radiometric signals give insight on the energy and features of the 13 paroxysms fed by NSEC, SO2 and halogen fluxes shed light on the likely mechanisms triggering the eruptive phenomena. GPS data provided clear evidence of pressurization of Mt. Etna's plumbing system from May 2012 to middle February 2013 and depressurization during the February-April 2013 eruptive activity. Taking into account geochemical data, we propose that the paroxysms' sequence represented the climax of a waxing-waning phase of degassing that had started as early as December 2012, and eventually ended in April 2013. Integration of the multidisciplinary observations suggests that the February-April 2013 eruptive activity reflects a phase of release of a volatile-rich batch of magma that had been stored in the shallow volcano plumbing system at least 4 months before, and with the majority of gas released between February and March 2013
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