186 research outputs found

    Vertical distribution of the macrofauna in polluted sediments from the harbour of Ceuta

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    Vertical distribution of the macrofauna and its relationship with physico-chemical parameters were studied in polluted sediments from the harbour of Ceuta. The samples were collected with cores (10 cm ˟ 17 cm ˟ 35 cm) by scuba divers. The following depths in the sediment column were included in the study: 0-2 cm, 2- 5 cm, 5-10 cm and more than 10 cm. The crustaceans Pariambus typicus Kröyer, 1844; Apseudes latreilli Milne-Edwards, 1820; Corophium runcicorne Della Valle, 1893; C. sextonae Crawford, 1937; the mollusc Parvicardium exiguum (Gmelin, 1791), and the polychaetes Pseudomalacoceros tridentata (Southern, 1914) and Exogone verrugera Cleparede, 1868 were found in the first 2 cm of the sediment, whereas the mollusc Loripes lacteus (L., 1758) and the polychaetes Platynereis dumerilii Audouin & Milne Edwards; 1833; Cirratulus cirratus (Muller; 1776) and Cirriformia tentaculata (Montagu; 1808) were dominant in deeper strata; and size increased with depth. A multivariate analysis showed that the percentage of silt and clays; the total organic matter; and especially; the maltenes/asphaltenes ratio; were the main factors affecting species' vertical distribution.Se ha estudiado la distribución vertical de la macrofauna y su relación con las variables fisicoquímicas de los sedimentos contaminados del puerto de Ceuta. La obtención de las muestras se llevó a cabo mediante buceo con escafandra autónoma y empleando instrumentos de muestreo tipo core (10 cm ˟ 17 cm ˟ 35 cm), diferenciándose las siguientes profundidades en la columna de sedimento: 0-2 cm, 2-5 cm, 5-10 cm y más de 10 cm. Los crustáceos Pariambus typicus Kröyer, 1844; Apseudes latreilli Milne-Edwards, 1820; Corophium runcicorne Della Valle, 1893; C. sextonae Crawford, 1937; el molusco Parvicardium exiguum (Gmelin, 1791) y los poliquetos Pseudomalacoceros tridentata (Southern, 1914) y Exogone verrugera Cleparede, 1868 se localizaron en los dos primeros centímetros de sedimento, mientras que el molusco Loripes lacteus (L., 1758) y los poliquetos Platynereis dumerilii Audouin y Milne-Edwards, 1833; Cirratulus cirratus (Muller, 1776) y Cirriformia tentaculata (Montagu, 1808) dominaron en los niveles más profundos, observándose el incremento en el tamaño de los individuos con el aumento de la profundidad. Los análisis multivariantes reflejaron que el porcentaje de pelitas, la materia orgánica total y, especialmente, la relación lípidos malténicos/lípidos asfalténicos, fueron los principales factores condicionantes de la distribución vertical de las especies en el sedimento.Instituto Español de Oceanografí

    Re-use of construction and demolition residues and industrial wastes for the elaboration or recycled eco-efficient concretes

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    [EN] Production of residues from industries and construction and demolition sectors has increased during last years. The total amount of debris produced according to different estimations reaches values close to 42 million tonnes yr –1 . Much of this waste has been thrown to landfill, without considering its potential for reuse, recycling or valuation. The aim of this research is to describe some of the physical and mechanical properties of different laboratory-mixed concretes, using various proportions of additional materials recovered from industrial waste and demolition rubble. The added materials are included either as admixtures (forestry residues, cork dust, steel fibre) or in partial substitution of natural aggregates (wire from electrical residues, tyre rubber, white ceramic, sanitary porcelain or shale). The laboratory tests have followed the standard EN protocols. Assay results were variable according to the nature of the material added to the mix: organic materials and shale, despite the steel fibre reinforcement, reduce the compression strength, but are suitable for the manufacture of lightweight concrete for agricultural pavements, with certain flexion resistance and a relatively good behaviour to impact. The substitution of natural aggregates with ceramic and porcelain wastes produces a significant increase in compression resistance, making them suitable for the manufacture of concrete with characteristic resistances above 40 MPa, which can be used both for structures or other agricultural elements: separators, feeders, slat floors. As a conclusion can be stated the possibility of reuse these wastes for the production of structural or non-structural concrete, with different applications in agricultural engineerin

    Déjà vu: a reappraisal of the taphonomy of quarry VM4 of the Early Pleistocene site of Venta Micena (Baza Basin, SE Spain)

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    Venta Micena, an Early Pleistocene site of the Baza Basin (SE Spain), preserves a rich and diverse assemblage of large mammals. VM3, the main excavation quarry of the site, has been interpreted as a den of the giant hyaena Pachycrocuta brevirostris in the plain that surrounded the Baza palaeolake. Taphonomic analysis of VM3 has shown that the hyaenas scavenged the prey previously hunted by the hypercarnivores, transported their remains to the communal den, and consumed the skeletal parts according to their marrow contents and mineral density. In a recent paper (Luzón et al. in Sci Rep 11:13977, https://doi.org/10.1038/s41598-021-93261-1, 2021), a small sample of remains unearthed from VM4, an excavation quarry ~ 350 m distant from VM3, is analysed. The authors indicate several differences in the taphonomic features of this assemblage with VM3, and even suggest that a different carnivore could have been the agent involved in the bone accumulation process. Here, we make a comparative analysis of both quarries and analyse more skeletal remains from VM4. Our results indicate that the assemblages are broadly similar in composition, except for slight differences in the frequency of megaherbivores, carnivores and equids according to NISP values (but not to MNI counts), the degree of bone weathering, and the intensity of bone processing by the hyaenas. Given that VM4 and VM3 were not coeval denning areas of P. brevirostris, these differences suggest that during the years when the skeletal remains were accumulated by the hyaenas at VM3, the rise of the water table of the Baza palaeolake that capped with limestone the bones was delayed compared to VM4, which resulted in their more in-depth consumption by the hyaenas

    Insights on the Early Pleistocene Hominin Population of the Guadix-Baza Depression (SE Spain) and a Review on the Ecology of the First Peopling of Europe

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    The chronology and environmental context of the first hominin dispersal in Europe have been subject to debate and controversy. The oldest settlements in Eurasia (e.g., Dmanisi, ∼1.8 Ma) suggest a scenario in which the Caucasus and southern Asia were occupied ∼0.4 Ma before the first peopling of Europe. Barranco León (BL) and Fuente Nueva 3 (FN3), two Early Pleistocene archeological localities dated to ∼1.4 Ma in Orce (Guadix-Baza Depression, SE Spain), provide the oldest evidence of hominin presence in Western Europe. At these sites, huge assemblages of large mammals with evidence of butchery and marrow processing have been unearthed associated to abundant Oldowan tools and a deciduous tooth of Homo sp. in the case of BL. Here, we: (i) review the Early Pleistocene archeological sites of Europe; (ii) discuss on the subsistence strategies of these hominins, including new estimates of resource abundance for the populations of Atapuerca and Orce; (iii) use cartographic data of the sedimentary deposits for reconstructing the landscape habitable in Guadix-Baza; and (iv) calculate the size of the hominin population using an estimate of population density based on resource abundance. Our results indicate that Guadix-Baza could be home for a small hominin population of 350–280 individuals. This basin is surrounded by the highest mountainous reliefs of the Alpine-Betic orogen and shows a limited number of connecting corridors with the surrounding areas, which could have limited gene flow with other hominin populations. Isolation would eventually lead to bottlenecks, genetic drift and inbreeding depression, conditions documented in the wild dog population of the basin, which probably compromised the viability of the hominin population in the medium to long term. This explains the discontinuous nature of the archeological record in Guadix-Baza, a situation that can also be extrapolated to the scarcity of hominin settlements for these ancient chronologies in Europe

    Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV

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    We present final searches of the anomalous gammaWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wgamma, WW, and WZ production with leptonic final states. The analyzed data correspond to up to 8.6/fb of integrated luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96 TeV. We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2 TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154, -0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization, and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL

    Measurement of the photon+b+b-jet production differential cross section in ppˉp\bar{p} collisions at \sqrt{s}=1.96~\TeV

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    We present measurements of the differential cross section dsigma/dpT_gamma for the inclusive production of a photon in association with a b-quark jet for photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is the photon transverse momentum. The b-quark jets are required to have pT>15 GeV and rapidity |y_jet| < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the Fermilab Tevatron ppˉp\bar{p} Collider at sqrt(s)=1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the Sherpa and Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.

    Search for pair production of the scalar top quark in muon+tau final states

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    We present a search for the pair production of scalar top quarks (t~1\tilde{t}_{1}), the lightest supersymmetric partners of the top quarks, in ppˉp\bar{p} collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of {7.3 fb1fb^{-1}} collected with the \dzero experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a bb quark, a charged lepton, and a scalar neutrino (ν~\tilde{\nu}). We investigate final states arising from t~1t~1ˉbbˉμτν~ν~\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\mu\tau \tilde{\nu} \tilde{\nu} and t~1t~1ˉbbˉττν~ν~\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\tau\tau \tilde{\nu} \tilde{\nu}. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the (mt~1m_{\tilde{t}_{1}},mν~m_{\tilde{\nu}}) plane.Comment: Submitted to Phys. Lett.

    Search for Higgs bosons of the minimal supersymmetric standard model in p-pbar collisions at sqrt(s)=1.96 TeV

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    We report results from searches for neutral Higgs bosons produced in p-pbar collisions recorded by the Dzero experiment at the Fermilab Tevatron Collider. We study the production of inclusive neutral Higgs boson in the tautau final state and in association with a b quark in the btautau and bbb final states. These results are combined to improve the sensitivity to the production of neutral Higgs bosons in the context of the minimal supersymmetric standard model (MSSM). The data are found to be consistent with expectation from background processes. Upper limits on MSSM Higgs boson production are set for Higgs boson masses ranging from 90 to 300 GeV. We exclude tanBeta>20-30 for Higgs boson masses below 180 GeV. These are the most stringent constraints on MSSM Higgs boson production in p-pbar collisions.Comment: Submitted to Phys. Lett.
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