Control geomorfológico en el desarrollo de los suelos en la subcuenca hidrográfica Linga, Arequipa

La zona de estudio pertenece a la subcuenca Linga, en el Distrito de Cocachacra, Departamento de Arequipa (Figura 1). En esta zona aflora una gran variedad de rocas sedimentarias, metamórficas, volcánicas e intrusivas que abarcan un amplio rango de edad que van desde el Proterozoico hasta el Cuaternario, además existen unidades de relieve tales como montañas, colinas, lomas, llanuras y vallecitos, y zonas climáticas de desierto superárido con sus respectivos microclimas. Este trabajo tiene como objetivo realizar un análisis del desarrollo del suelo en las superunidades Linga y Punta Coles con la finalidad de comprender la relación existente entre el grado de desarrollo del suelo, el relieve del terreno y el microclima en el cual se dan lugar los procesos pedogéneticos. Este estudio se encuentra enmarcado dentro de las labores realizadas dentro de la cuenca hidrográfica del Río Tambo por el Proyecto de la Carta Nacional de Suelos de la Dirección de Geología Regional, INGEMMET. Los estudios de pedogénesis muestran que el material parental, relieve, clima, organismos y tiempo, son los factores relevantes en el desarrollo de un suelo. En este trabajo, se ha evaluado el grado de desarrollo de los suelos en función de la variación del relieve y microclima en unidades intrusivas del Cretácico superior - Paleoceno y Jurásico inferior a medio (Superunidad Linga y PuntaColes). Se establecieron 2 catenas, 4 pedones en la superunidad Linga y 3 pedones en la superunidad Punta Coles. Los pedones de ambas catenas corresponden a depósitos residuales, con grado de desarrollo desde muy superficiales a superficiales. Las observaciones sugieren que existe un claro contraste entre los suelos generados en zonas de montañas, colinas y lomas, correspondiendo a un dominio del factor relieve y en menor medida al microclima

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

Geología del pisco, valle de Ica

El trabajo presenta las características del terruño del pisco del valle de Ica, con énfasis en el medio físico; se rescata y valora la existencia de una combinación exacta entre geología, clima, relieve y suelos, que dan lugar a un terreno propicio y perfecto para el nacimiento del pisco. La publicación invita a ver la geología desde otra perspectiva, nos sumerge a conocer los atributos naturales necesarios para producir el pisco, los cuales obedecen a la evolución geológica de millones de años, donde los procesos geológicos internos y externos han logrado modelar el valle y han condicionado el clima e hidrografía; el desarrollo de los suelos es la cuna de la esencia de uvas que le dan al pisco el sabor y el aroma propios de este valle. Asimismo, se evalúan las características y sus implicancias entre geología, relieve, suelo, mineralogía y química, que en conjunto le otorgan especificidad y tipificación de calidad y sabor al pisco del valle de Ica

Elliptic flow of electrons from heavy-flavour hadron decays at mid-rapidity in Pb–Pb collisions at √sNN = 2.76 TeV

The elliptic flow of electrons from heavy-flavour hadron decays at mid-rapidity (|y| < 0.7) is measured in Pb-Pb collisions at sNN−−−√=2.76 TeV with ALICE at the LHC. The particle azimuthal distribution with respect to the reaction plane can be parametrized with a Fourier expansion, where the second coefficient (v2) represents the elliptic flow. The v2 coefficient of inclusive electrons is measured in three centrality classes (0-10%, 10-20% and 20-40%) with the event plane and the scalar product methods in the transverse momentum (pT) intervals 0.5-13 GeV/c and 0.5-8 GeV/c, respectively. After subtracting the background, mainly from photon conversions and Dalitz decays of neutral mesons, a positive v2 of electrons from heavy-flavour hadron decays is observed in all centrality classes, with a maximum significance of 5.9σ in the interval 2< pT < 2.5 GeV/c in semi-central collisions (20-40%). The value of v2 decreases towards more central collisions at low and intermediate pT (0.5 < pT < 3 GeV/c). The v2 of electrons from heavy-flavour hadron decays at mid-rapidity is found to be similar to the one of muons from heavy-flavour hadron decays at forward rapidity (2.5 < y < 4). The results are described within uncertainties by model calculations including substantial elastic interactions of heavy quarks with an expanding strongly-interacting medium

Correlated event-by-event fluctuations of flow harmonics in Pb–Pb collisions at √sNN = 2.76 TeV

We report the measurements of correlations between event-by-event fluctuations of amplitudes of anisotropic flow harmonics in nucleus-nucleus collisions, obtained for the first time using a new analysis method based on multiparticle cumulants in mixed harmonics. This novel method is robust against systematic biases originating from non-flow effects and by construction any dependence on symmetry planes is eliminated. We demonstrate that correlations of flow harmonics exhibit a better sensitivity to medium properties than the individual flow harmonics. The new measurements are performed in Pb-Pb collisions at the centre-of-mass energy per nucleon pair of sNN−−−√=2.76 TeV by the ALICE experiment at the Large Hadron Collider (LHC). The centrality dependence of correlation between event-by-event fluctuations of the elliptic, v2, and quadrangular, v4, flow harmonics, as well as of anti-correlation between v2 and triangular, v3, flow harmonics are presented. The results cover two different regimes of the initial state configurations: geometry-dominated (in mid-central collisions) and fluctuation-dominated (in the most central collisions). Comparisons are made to predictions from MC-Glauber, viscous hydrodynamics, AMPT and HIJING models. Together with the existing measurements of individual flow harmonics the presented results provide further constraints on initial conditions and the transport properties of the system produced in heavy-ion collisions

Measurement of transverse energy at midrapidity in Pb–Pb collisions at √sNN = 2.76 TeV

We report the transverse energy (ET) measured with ALICE at midrapidity in Pb-Pb collisions at sNN−−−√ = 2.76 TeV as a function of centrality. The transverse energy was measured using identified single particle tracks. The measurement was cross checked using the electromagnetic calorimeters and the transverse momentum distributions of identified particles previously reported by ALICE. The results are compared to theoretical models as well as to results from other experiments. The mean ET per unit pseudorapidity (η), ⟨dET/dη⟩, in 0-5% central collisions is 1737 ± 6(stat.) ± 97(sys.) GeV. We find a similar centrality dependence of the shape of ⟨dET/dη⟩ as a function of the number of participating nucleons to that seen at lower energies. The growth in ⟨dET/dη⟩ at the LHC sNN−−−√ exceeds extrapolations of low energy data. We observe a nearly linear scaling of ⟨dET/dη⟩ with the number of quark participants. With the canonical assumption of a 1 fm/c formation time, we estimate that the energy density in 0-5% central Pb-Pb collisions at sNN−−−√ = 2.76 TeV is 12.3 ± 1.0 GeV/fm3\xspace and that the energy density at the most central 80 fm2 of the collision is at least 21.5 ± 1.7 GeV/fm3. This is roughly 2.3 times that observed in 0-5% central Au-Au collisions at sNN−−−√ = 200 GeV

Centrality dependence of the charged-particle multiplicity density at midrapidity in Pb–Pb collisions at √sNN = 5.02 TeV

The pseudorapidity density of charged particles (dNch/dη) at mid-rapidity in Pb-Pb collisions has been measured at a center-of-mass energy per nucleon pair of sNN−−−√ = 5.02 TeV. It increases with centrality and reaches a value of 1943±54 in |η|<0.5 for the 5% most central collisions. A rise in dNch/dη as a function of sNN−−−√ for the most central collisions is observed, steeper than that observed in proton-proton collisions and following the trend established by measurements at lower energy. The centrality dependence of dNch/dη as a function of the average number of participant nucleons, ⟨Npart⟩, calculated in a Glauber model, is compared with the previous measurement at lower energy. A constant factor of about 1.2 describes the increase in 2⟨Npart⟩⟨dNch/dη⟩ from sNN−−−√ = 2.76 TeV to sNN−−−√ = 5.02 TeV for all centrality intervals, within the measured range of 0-80% centrality. The results are also compared to models based on different mechanisms for particle production in nuclear collisions

Charge-dependent flow and the search for the Chiral Magnetic Wave in Pb–Pb collisions at √sNN = 2.76 TeV

We report on measurements of a charge-dependent flow using a novel three-particle correlator with ALICE in Pb-Pb collisions at the LHC, and discuss the implications for observation of local parity violation and the Chiral Magnetic Wave (CMW) in heavy-ion collisions. Charge-dependent flow is reported for different collision centralities as a function of the event charge asymmetry. While our results are in qualitative agreement with expectations based on the CMW, the nonzero signal observed in higher harmonics correlations indicates a possible significant background contribution. We also present results on a differential correlator, where the flow of positive and negative charges is reported as a function of the mean charge of the particles and their pseudorapidity separation. We argue that this differential correlator is better suited to distinguish the differences in positive and negative charges expected due to the CMW and the background effects, such as local charge conservation coupled with strong radial and anisotropic flow

Centrality dependence of charged jet production in p–Pb collisions at √sNN = 5.02 TeV

Measurements of charged jet production as a function of centrality are presented for p-Pb collisions recorded at sNN−−−√=5.02 TeV with the ALICE detector. Centrality classes are determined via the energy deposit in neutron calorimeters at zero degree, close to the beam direction, to minimise dynamical biases of the selection. The corresponding number of participants or binary nucleon-nucleon collisions is determined based on the particle production in the Pb-going rapidity region. Jets have been reconstructed in the central rapidity region from charged particles with the anti-kT algorithm for resolution parameters R=0.2 and R=0.4 in the transverse momentum range 20 to 120 GeV/c. The reconstructed jet momentum and yields have been corrected for detector effects and underlying-event background. In the five centrality bins considered, the charged jet production in p-Pb collisions is consistent with the production expected from binary scaling from pp collisions. The ratio of jet yields reconstructed with the two different resolution parameters is also independent of the centrality selection, demonstrating the absence of major modifications of the radial jet structure in the reported centrality classes

Pseudorapidity dependence of the anisotropic flow of charged particles in Pb–Pb collisions at √sNN = 2.76 TeV

We present measurements of the elliptic (v2), triangular (v3) and quadrangular (v4) anisotropic azimuthal flow over a wide range of pseudorapidities (−3.5<η<5). The measurements are performed with Pb-Pb collisions at sNN−−−√=2.76 TeV using the ALICE detector at the Large Hadron Collider (LHC). The flow harmonics are obtained using two- and four-particle correlations from nine different centrality intervals covering central to peripheral collisions. We find that the shape of vn(η) is largely independent of centrality for the flow harmonics n=2−4, however the higher harmonics fall off more steeply with increasing |η|. We assess the validity of extended longitudinal scaling of v2 by comparing to lower energy measurements, and find that the higher harmonic flow coefficients are proportional to the charged particle densities at larger pseudorapidities. Finally, we compare our measurements to both hydrodynamical and transport models, and find they both have challenges when it comes to describing our data