263 research outputs found

    Indigenous peoples' control over contemporary challenges of traditional subsistence socio-ecological systems sustainability: The case from the taiga zone of Siberia

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    Traditional subsistence socio-ecological systems (TSSESs) based on hunting, gathering and fishing are widely spread all-over the taiga zone of Siberia. Nowadays, they are strongly impacted by several drivers of change, coming from human activities and climate changes with cascading both positive and negative effects on all components of ecosystem functions and services. The effects may influence quality of life of indigenous people and human capacities. Key multi-scale issues and possible ways of their solution are identified in TSSESs of Evenkia municipal district of the Krasnoyarsk region based on scientific research and traditional local knowledge and perceptions integration. Among key issues the degradation of ecosystems heavily impacting local subsistence resources availability (fish and meat for food as well as wild animals’ skins for sale) is the most urgent for the indigenous people living on land. Several negative driving forces both socio-economic and natural such as widespread poaching, forest land auctions and increasing annual rent obligations for hunting grounds to the indigenous peoples, imposing limits (quarters) without taking into account real subsistence need of indigenous communities, non-compensated impact of spreading infrastructure and logging on taiga forest ecosystems and hunting grounds, as well as climate changes, are impacting quality of life and human capacities of indigenous people. This analysis of key issues and driving forces leading to them gives us opportunity to propose several ways of such issues solution. The improvement of control and management of TSSESs sustainability with active participation of indigenous people is the principle way for achieving TSSESs resilience and sustainability

    Features of Luminescent Properties of Alginate Aerogels with Rare Earth Elements as Photoactive Cross-Linking Agents

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    Luminescent aerogels based on sodium alginate cross-linked with ions of rare earth elements (Eu3+, Tb3+, Sm3+) and containing phenanthroline, thenoyltrifluoroacetone, dibenzoylmethane, and acetylacetone as ligands introduced into the matrix during the impregnation of alginate aerogels (AEG), were obtained for the first time in a supercritical carbon dioxide medium. The impregnation method used made it possible to introduce organically soluble sensitizing ligands into polysaccharide matrices over the entire thickness of the sample while maintaining the porous structure of the aerogel. It is shown that the pore size and their specific area are 150 nm and 270 m2/g, respectively. Moreover, metal ions with content of about 23 wt.%, acting as cross-linking agents, are uniformly distributed over the thickness of the sample. In addition, the effect of sensitizing ligands on the luminescence intensity of cross-linked aerogel matrices is considered. The interaction in the resulting metal/ligand systems is unique for each pair, which is confirmed by the detection of broad bands with individual positions in the luminescence excitation spectra of photoactive aerogels

    Photocurable Methacrylate Derivatives of Polylactide: A Two-Stage Synthesis in Supercritical Carbon Dioxide and 3D Laser Structuring

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    A two-stage polylactide modification was performed in the supercritical carbon dioxide medium using the urethane formation reaction. The modification resulted in the synthesis of polymerizable methacrylate derivatives of polylactide for application in the spatial 3D structuring by laser stereolithography. The use of the supercritical carbon dioxide medium allowed us to obtain for the first time polymerizable oligomer-polymer systems in the form of dry powders convenient for further application in the preparation of polymer compositions for photocuring. The photocuring of the modified polymers was performed by laser stereolithography and two-photon crosslinking. Using nanoindentation, we found that Young’s modulus of the cured compositions corresponded to the standard characteristics of implants applied in regenerative medicine. As shown by thermogravimetric analysis, the degree of crosslinking and, hence, the local stiffness of scaffolds were determined by the amount of the crosslinking agent and the photocuring regime. No cytotoxicity was observed for the structures

    Measurement of Ds + production and nuclear modification factor in Pb-Pb collisions at √sNN = 2.76 TeV

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    The production of prompt D s + mesons was measured for the first time in collisions of heavy nuclei with the ALICE detector at the LHC. The analysis was performed on a data sample of Pb-Pb collisions at a centre-of-mass energy per nucleon pair, sNN−−−√ , of 2.76 TeV in two different centrality classes, namely 0–10% and 20–50%. D s + mesons and their antiparticles were reconstructed at mid-rapidity from their hadronic decay channel D s +  → ϕπ +, with ϕ → K−K+, in the transverse momentum intervals 4 < p T < 12GeV/c and 6 < p T < 12 GeV/c for the 0–10% and 20–50% centrality classes, respectively. The nuclear modification factor R AA was computed by comparing the p T-differential production yields in Pb-Pb collisions to those in proton-proton (pp) collisions at the same energy. This pp reference was obtained using the cross section measured at s√=7 TeV and scaled to s√=2.76 TeV. The R AA of D s + mesons was compared to that of non-strange D mesons in the 10% most central Pb-Pb collisions. At high p T (8 < p T < 12 GeV/c) a suppression of the D s + -meson yield by a factor of about three, compatible within uncertainties with that of non-strange D mesons, is observed. At lower p T (4 < p T < 8 GeV/c) the values of the D s + -meson R AA are larger than those of non-strange D mesons, although compatible within uncertainties. The production ratios D s + /D0 and D s + /D+ were also measured in Pb-Pb collisions and compared to their values in proton-proton collisions

    Pseudorapidity densities of charged particles with transverse momentum thresholds in pp collisions at √ s = 5.02 and 13 TeV

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    The pseudorapidity density of charged particles with minimum transverse momentum (pT) thresholds of 0.15, 0.5, 1, and 2 GeV/c is measured in pp collisions at the center of mass energies of √s=5.02 and 13 TeV with the ALICE detector. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity (η) within 0.8pT larger than the corresponding threshold. In addition, measurements without pT-thresholds are performed for inelastic and nonsingle-diffractive events as well as for inelastic events with at least one charged particle having |η|2GeV/c), highlighting the importance of such measurements for tuning event generators. The new measurements agree within uncertainties with results from the ATLAS and CMS experiments obtained at √s=13TeV.

    Measurement of beauty production via non-prompt D0{\rm D}^{0} mesons in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 5.02 TeV

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    The production of non-prompt D0{\rm D}^{0} mesons from beauty-hadron decays was measured at midrapidity (y5 GeV/c\left| y \right| 5~\mathrm{GeV}/c in the 0100-10% central Pb-Pb collisions. The data are described by models that include both collisional and radiative processes in the calculation of beauty-quark energy loss in the quark-gluon plasma, and quark recombination in addition to fragmentation as a hadronization mechanism. The ratio of the non-prompt to prompt D0{\rm D}^{0}-meson RAAR_{\rm AA} is larger than unity for pT>4 GeV/cp_{\rm T} > 4~\mathrm{GeV}/c in the 0100-10% central Pb-Pb collisions, as predicted by models in which beauty quarks lose less energy than charm quarks in the quark-gluon plasma because of their larger mass

    First measurement of the absorption of 3He^{3}\overline{\rm He} nuclei in matter and impact on their propagation in the galaxy

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    Antimatter particles such as positrons and antiprotons abound in the cosmos. Much less common are light antinuclei, composed of antiprotons and antineutrons, which can be produced in our galaxy via high-energy cosmic-ray collisions with the interstellar medium or could also originate from the annihilation of the still undiscovered dark-matter particles. On Earth, the only way to produce and study antinuclei with high precision is to create them at high-energy particle accelerators like the Large Hadron Collider (LHC). Though the properties of elementary antiparticles have been studied in detail, knowledge of the interaction of light antinuclei with matter is rather limited. This work focuses on the determination of the disappearance probability of \ahe when it encounters matter particles and annihilates or disintegrates. The material of the ALICE detector at the LHC serves as a target to extract the inelastic cross section for \ahe in the momentum range of 1.17p<101.17 \leq p < 10 GeV/cc. This inelastic cross section is measured for the first time and is used as an essential input to calculations of the transparency of our galaxy to the propagation of 3He^{3}\overline{\rm He} stemming from dark-matter decays and cosmic-ray interactions within the interstellar medium. A transparency of about 50% is estimated using the GALPROP program for a specific dark-matter profile and a standard set of propagation parameters. For cosmic-ray sources, the obtained transparency with the same propagation scheme varies with increasing 3He^{3}\overline{\rm He} momentum from 25% to 90%. The absolute uncertainties associated to the 3He^{3}\overline{\rm He} inelastic cross section measurements are of the order of 10%-15%. The reported results indicate that 3He^{3}\overline{\rm He} nuclei can travel long distances in the galaxy, and can be used to study cosmic-ray interactions and dark-matter decays

    Study of the p-p-K+^+ and p-p-K^- dynamics using the femtoscopy technique

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    International audienceThe interactions of kaons (K) and antikaons (K\mathrm{\overline{K}}) with few nucleons (N) were studied so far using kaonic atom data and measurements of kaon production and interaction yields in nuclei. Some details of the three-body KNN and K\mathrm{\overline{K}}NN dynamics are still not well understood, mainly due to the overlap with multi-nucleon interactions in nuclei. An alternative method to probe the dynamics of three-body systems with kaons is to study the final state interaction within triplet of particles emitted in pp collisions at the Large Hadron Collider, which are free from effects due to the presence of bound nucleons. This Letter reports the first femtoscopic study of p-p-K+^+ and p-p-K^- correlations measured in high-multiplicity pp collisions at s\sqrt{s} = 13 TeV by the ALICE Collaboration. The analysis shows that the measured p-p-K+^+ and p-p-K^- correlation functions can be interpreted in terms of pairwise interactions in the triplets, indicating that the dynamics of such systems is dominated by the two-body interactions without significant contributions from three-body effects or bound states

    Studying strangeness and baryon production mechanisms through angular correlations between charged Ξ\Xi baryons and identified hadrons in pp collisions at s\sqrt{s} = 13 TeV

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    International audienceThe angular correlations between charged Ξ\Xi baryons and associated identified hadrons (pions, kaons, protons, Λ\Lambda baryons, and Ξ\Xi baryons) are measured in pp collisions at s=13\sqrt{s} = 13 TeV with the ALICE detector to give insight into the particle production mechanisms and balancing of quantum numbers on the microscopic level. In particular, the distribution of strangeness is investigated in the correlations between the doubly-strange Ξ\Xi baryon and mesons and baryons that contain a single strange quark, K and Λ\Lambda. As a reference, the results are compared to Ξπ\Xi\pi and Ξp\Xi\mathrm{p} correlations, where the associated mesons and baryons do not contain a strange valence quark. These measurements are expected to be sensitive to whether strangeness is produced through string breaking or in a thermal production scenario. Furthermore, the multiplicity dependence of the correlation functions is measured to look for the turn-on of additional particle production mechanisms with event activity. The results are compared to predictions from the string-breaking model PYTHIA 8, including tunes with baryon junctions and rope hadronisation enabled, the cluster hadronisation model HERWIG 7, and the core-corona model EPOS-LHC. While some aspects of the experimental data are described quantitatively or qualitatively by the Monte Carlo models, no one model can match all features of the data. These results provide stringent constraints on the strangeness and baryon number production mechanisms in pp collisions
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