Low-pT Collective Flow Induces High-pT Jet Quenching

Data on low-pT hadronic spectra are widely regarded as evidence of a hydrodynamic expansion in nucleus-nucleus collisions. In this interpretation, different hadron species emerge from a common medium that has built up a strong collective velocity field. Here, we show that the existence of a collective flow field implies characteristic modifications of high-pT parton fragmentation. We generalize the formalism of parton energy loss to the case of flow-induced, oriented momentum transfer. We also discuss how to embed this calculation in hydrodynamic simulations. Flow effects are found to result generically in characteristic asymmetries in the eta-phi-plane of jet energy distributions and of multiplicity distributions associated to high-pT trigger particles. But collective flow also contributes to the medium-induced suppression of single inclusive high-pT hadron spectra. In particular, we find that low-pT elliptic flow can induce a sizeable additional contribution to the high-pT azimuthal asymmetry by selective elimination of those hard partons which propagate with significant inclination against the flow field. This reduces at least partially the recently observed problem that models of parton energy loss tend to underpredict the large azimuthal asymmetry v2 of high-pT hadronic spectra in semi-peripheral Au+Au collisions.Comment: 26 pages LaTeX, 11 eps-figure

Defining New Parameters for Green Engineering Design of Treatment Reactors

This study proposes a green way to design Plug Flow Reactors (PFR) that use biodegradable polymer solutions, capable of contaminant retaining, for industrial wastewater treatment. Usually, to the design of a reactor, the reaction rate is determined by tests on a Continuous Stirred-Tank (CST), these generate toxic effluents and also increase the cost of the design. In this work, empirical expressions (called “slip functions”), in terms of the average concentration of the contaminant, were developed through the study of the transport behaviour of CrVI into solutions of xanthan gum. “In situ” XRμF was selected as a no-invasive micro-technique to determine local concentrations. Slip functions were used with laboratory experiments planned in similar conditions using Plug Flow Reactors, to obtain useful dimensionless parameters for the industrial design

Determinación espectroquímica de impurezas en plata

Con el fin de verificar el grado de pureza de la plata empleada principalmente para la fabricación de fusibles, se ha aplicado el análisis espectroquímico por su gran sensibilidad y rapidez. Debido a la gran variedad en el diámetro de los alambres y ante la imposibilidad de disponer de los patrones standard para cada medida, fue necesario disolver la muestra y realizar el análisis sobre las sales (nitratos). Las muestras standard se prepararon por el mismo procedimiento, empleando sustancias de pureza espectroscópica (Johnson Matthey). Esta técnica de análisis nos permite determinar once elementos (Cu, Cd, Pb, Ni, Sn, Al, Zn, Pt, Pd, Ir, Au). Se utilizo un espectrógrafo Z-3 (Jobin-Yvon), fuente de excitación G.M.60 (de Durr) y densitómetro 21-051 (Jarrell-Ash).Because of its great sensitivity and time-saving characteristics spectrochemical analysis has "been applied to the purity control of silver to he used mainly in fuse manufacture. As wires differ widely in their diameters and it is almost impossible to obtain standards por each size, it was necessary to disolve the sample and analize the resulting salts (nitrates). Standard samples were prepared making use of the procedure on spectroscopically pure materials (Johnson Matthey). This analytical technique allows the determination of eleven elements, i.e. Cu, Cd, Pb, Ni, Sn, Al, Zn, Pt, Pd, Ir, Au. Instrumentation used includes Jobin-Yvon Z-3 spectrograph, Durr G.M.60 excitation source and Jarrell-Ash,model 21-051 densitometer

Effective-action model for dynamical scalarization beyond the adiabatic approximation

In certain scalar-field extensions to general relativity, scalar charges can develop on compact objects in an inspiraling binary -- an effect known as dynamical scalarization. This effect can be modeled using effective-field-theory methods applied to the binary within the post-Newtonian approximation. Past analytic investigations focused on the adiabatic (or quasi-stationary) case for quasi-circular orbits. In this work, we explore the full dynamical evolution around the phase transition to the scalarized regime. This allows for generic (eccentric) orbits and to quantify nonadiabatic (e.g., oscillatory) behavior during the phase transition. We also find that even in the circular-orbit case, the onset of scalarization can only be predicted reliably when taking the full dynamics into account, i.e., the adiabatic approximation is not appropriate. Our results pave the way for accurate post-Newtonian predictions for dynamical scalarization effects in gravitational waves from compact binaries.Comment: 15 pages, 11 figures. v2: matches published versio

Neuromanagement y neuroliderazgo : Cómo se aplican los avances de las neurociencias a la conducción y gestión de organizaciones

En la época en que nos toca vivir, la constatación científica de que existe una base neurobiológica tanto en el intelecto como en las emociones, los sentimientos y el comportamiento social ha provocado una verdadera revolución. Por ello estamos transitando desde el management al neuromanagement, desde el liderazgo al neuroliderazgo, desde la economía a la neuroeconomía, desde el marketing al neuromarketing.Facultad de Ciencias Económica

Burdigalian deposits of the Santa Cruz Formation in the Sierra Baguales, Austral (Magallanes) Basin: Age, depositional environment and vertebrate fossils

Indexación: Web of Science; Scielo.ABSTRACT. A succession of marine and continental strata on the southern flank of Cerro Cono in the Sierra Baguales, northeast of Torres del Paine, can be correlated with stratigraphic units exposed along the southern border of the Lago Argentino region in Santa Cruz Province, Argentina. These include the Estancia 25 de Mayo Formation and the basal part of the Santa Cruz Formation. The lithological correlation is also confirmed by detrital zircon ages (maximum age of 18.23±0.26 Ma) and a rich assemblage of terrestrial vertebrate fossils, biostratigraphically equivalent to a postColhuehuapian, pre-Santacrucian South American Land Mammal Age (SALMA) fauna, suggesting a range of 19 to 17.8 Ma. Similar ages have been obtained from the basal part of the Santa Cruz Formation at Estancia Quién Sabe in southwestern Argentina, supporting the assumption of a regional continuity between these deposits. A measured lithostratigraphic column is presented and the depositional environment is interpreted as a coastal plain with small, meandering rivers and ephemeral floodplain lakes. The sedimentation coincides with intensified uplift of the Patagonian Andes during the ‘Quechua Phase’ of Andean tectonism, which is reflected by a change in paleocurrent directions from northwest to east-northeast. Keywords: Burdigalian, Santa Cruz Formation, Santacrucian SALMA, ‘Notohippidian’ fauna, Meandering rivers.RESUMEN. Una sucesión de estratos marinos y continentales en el flanco meridional del cerro Cono, en la sierra Baguales, al noreste de Torres del Paine, se correlaciona con estratos al sur de la región de lago Argentino en la Provincia de Santa Cruz, República Argentina. Estas unidades incluyen la Formación Estancia 25 de Mayo y la parte basal de la Formación Santa Cruz. La correlación litológica es, además, confirmada por datación de circones detríticos (edad máxima de 18,23±0,26 Ma) y un variado ensamble de vertebrados fósiles terrestres de edad post-Colhuehuapense a pre-Santacrucense en la escala de Edades Mamífero Sudamericanas (EMAS), con un rango temporal de entre 19 a 17,8 Ma. Edades similares han sido reportadas para la parte basal de la Formación Santa Cruz, en estancia Quién Sabe, en el suroeste de Argentina, ratificando la continuidad regional entre estos depósitos. Se presenta una columna estratigráfica y se interpreta el ambiente de depositación como una llanura costera con pequeños ríos sinuosos y lagos efímeros. La edad de sedimentación coincide con el solevantamiento de los Andes Patagónicos durante la 'Fase Quechua', lo que se ve reflejado por un cambio en la dirección de las paleocorrientes desde el noroeste hacia el este-noreste.http://ref.scielo.org/csxwd

Conformal diagrams for the gravitational collapse of a spherical dust cloud

We present an algorithm for the construction of conformal coordinates in the interior of a spherically symmetric, collapsing matter cloud in general relativity. This algorithm is based on the numerical integration of the radial null geodesics and a local analysis of their behavior close to the singularity. As an application, we consider a collapsing spherical dust cloud, generate the corresponding conformal diagram and analyze the structure of the resulting singularity. A new bound on the initial data which guarantees that the singularity is visible from future null infinity is also obtained.Comment: added a new subsection with a phase space analysis, 23 pages, 8 figure

Structure, Ionization and Fragmentation of Neutral and Positively Charged Hydrogenated Carbon Clusters: CnHq+ m (n = 1 - 5, m = 1 - 4, Q = 0 - 3)

The CnHq+m family was studied at the DFT-B3LYP//CCSD(T) level of theory. Dissosiation energies, ionization potentials, geometries and frequencies were obtained. Different trends for these properteis have been observed and analyzed. The fragmentation behaviour has been studied within a combinatorial point of vie