Mass dependence of vector meson photoproduction off protons and nuclei within the energy-dependent hot-spot model

We study the photoproduction of vector mesons off proton and off nuclear targets. We work within the colour dipole model in an approach that includes subnucleon degrees of freedom, so-called hot spots, whose positions in the impact-parameter plane change event-by-event. The key feature of our model is that the number of hot spots depends on the energy of the photon--target interaction. Predictions are presented for exclusive and dissociative production of $\rho^{0}$, $\mathrm{J/}\psi$, and $\Upsilon(1S)$ off protons, as well as for coherent and incoherent photoproduction of $\rho^{0}$ off nuclear targets, where Xe, Au, and Pb nuclei are considered. We find that the mass dependence of dissociative production off protons as a function of the energy of the interaction provides a further handle to search for saturation effects at HERA, the LHC and future colliders. We also find that the coherent photonuclear production of $\rho^{0}$ is sensitive to fluctuations in the subnucleon degrees of freedom at RHIC and LHC energies.Comment: 19 pages, 4 figures. Typo in legend of figs. 1 and 2 correcte

Sistematización de una experiencia. Quebrando esquemas y venciendo el miedo: Teatro espontáneo como una práctica de resistencia y legitimación social

Tesis (Magíster en Terapia Ocupacional)Esta tesis tiene como interés rescatar una experiencia concreta de Teatro Espontáneo (T.E.) con un grupo de personas con diagnósticos psiquiátricos severos que se encuentran en un contexto de rehabilitación en una institución de salud. Se propone mostrar la realidad de este grupo y su forma de expresarla, reflexionarla y abrir caminos de transformación social. Se hace énfasis en un enfoque crítico con un interés ético de transformación. Para estos propósitos se llevó a cabo una investigación cualitativa de tipo descriptiva, sostenida en una sistematización de la experiencia, esta experiencia tiene una duración de un año completo (2014) y da cuenta de un proceso vivido en un taller de T.E. en el cual se transita con el grupo por diversos momentos dando cuenta de un camino de desarrollo y conciencia grupal. Al realizar el análisis de la información se concluye que el T.E. facilita la expresión grupal, desde lo corporal, lo reflexivo y lo social. El grupo logra construir un espacio de visibilización social, quitándose el rotulo de “paciente psiquiátrico”. En este contexto el T.E. logra ser una herramienta de liberación de la locura reprimida por la psiquiatría y por los contextos políticos históricos actuales. También se identifica que las vivencias relatadas por el grupo, están determinadas transversalmente por la experiencia del estigma, de esta forma, el T.E. se transforma en una herramienta de resistencia permitiéndole al grupo salir al encuentro del medio externo mostrando su identidad. La investigación permite visibilizar a la Terapia Ocupacional desde un sentido ético y político, ya que abre caminos a la expresión de lo reprimido social y científicamente, también enriquecer su relación con otros saberes como el Teatro Espontaneo, para lograr ser un aporte concreto en procesos de conciencia y transformación grupal

Universal field equations for metric-affine theories of gravity

We show that almost all metric--affine theories of gravity yield Einstein equations with a non--null cosmological constant $\Lambda$. Under certain circumstances and for any dimension, it is also possible to incorporate a Weyl vector field $W_\mu$ and therefore the presence of an anisotropy. The viability of these field equations is discussed in view of recent astrophysical observations.Comment: 13 pages. This is a copy of the published paper. We are posting it here because of the increasing interest in f(R) theories of gravit

Herschel, Spitzer and Magellan infrared observations of the star-forming region RCW 121 (IRAS 17149−3916)

We present new deep near-infrared broad- and narrow-band imaging and low-resolution spec-troscopy of the star formation region RCW 121 (IRAS 17149−3916) which we analyse incombination withHerschel(70, 160, 250, 350 and 500μm) andSpitzer(3.6, 4.5, 5.8 and 8μm)images. The near-infrared photometry reveals the presence of a stellar cluster of approximatesize of 92 arcsec which is composed of at least 264 members, approximately 25 per cent ofthese showing excess emission atλ>2.0μm, indicative of circumstellar discs. Isochronescorresponding to ages 0.5–1.0 Myr andAV=7.8 fit well the position of a large fraction of likelycluster members in theKsversusH−Ksdiagram. We find three massive star-forming coreslocated in the boundaries of an expanding HIIregion ionized by a central O-type star. Fromtheir far-infrared spectral energy distributions (SEDs) we derive masses and temperatures ofthe dense cores. When these young stellar objects (YSOs) have warm emission components,the 1.2–500μm SEDs are fitted with Robitaille et al.’s star–disc-envelope model to obtain theirphysical parameters. The masses of the three YSOs are between 8 and 10 M . The youngestsite (core I) is undetected atλ<100μm and is at the earliest evolutionary stage that cancurrently be detected. The other two cores (II and III) contain YSOs of similar masses andhave near-infrared counterparts, which imply a more advanced evolutionary stage. The YSOat core II has been found to have associated a jet, with strong H2line emission, co-existingwith an H2O maser source. RCW 121 is another example of multiple star formation beingtriggered by the expansion of a single HIIregion.Fil: Tapia, M.. Universidad Nacional Autónoma de México; MéxicoFil: Persi, P.. Istituto Astrofisica e Planetologia Spaziale. Roma; ItaliaFil: Roth, Markus Albert. Las Campanas Observatory. La Serena; ChileFil: Elia, D.. Istituto Astrofisica e Planetologia Spaziale. Roma; ItaliaFil: Molinari, S.. Istituto Astrofisica e Planetologia Spaziale. Roma; ItaliaFil: Saldaño, Hugo Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Gomez, Mercedes Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentin

Separable Measurement Estimation of Density Matrices and its Fidelity Gap with Collective Protocols

We show that there exists a gap between the performance of separable and collective measurements in qubit mixed-state estimation that persists in the large sample limit. We characterize such gap in terms of the corresponding bounds on the mean fidelity. We present an adaptive protocol that attains the separable-measurement bound. This (optimal separable) protocol uses von Neumann measurements and can be easily implemented with current technology.Comment: version published in PR

Phosphene-guided transcranial magnetic stimulation of occipital but not parietal cortex suppresses stimulus visibility.

Transcranial magnetic stimulation (TMS) applied over the occipital lobe approximately 100 ms after the onset of a stimulus decreases its visibility if it appears in the location of the phosphene. Because phosphenes can also be elicited by stimulation of the parietal regions, we asked if the same procedure that is used to reduce visibility of stimuli with occipital TMS will lead to decreased stimulus visibility when TMS is applied to parietal regions. TMS was randomly applied at 0-130 ms after the onset of the stimulus in steps of 10 ms in occipital and parietal regions. Participants responded to the orientation of the line stimulus and rated its visibility. We replicate previous reports of phosphenes from both occipital and parietal TMS. As previously reported, we also observed visual suppression around the classical 100 ms window both in the objective line orientation and subjective visibility responses with occipital TMS. Parietal stimulation, on the other hand, did not consistently reduce stimulus visibility in any time window. http://dx.doi.org/10.1007/s00221-014-3923-z

Optimal full estimation of qubit mixed states

We obtain the optimal scheme for estimating unknown qubit mixed states when an arbitrary number N of identically prepared copies is available. We discuss the case of states in the whole Bloch sphere as well as the restricted situation where these states are known to lie on the equatorial plane. For the former case we obtain that the optimal measurement does not depend on the prior probability distribution provided it is isotropic. Although the equatorial-plane case does not have this property for arbitrary N, we give a prior-independent scheme which becomes optimal in the asymptotic limit of large N. We compute the maximum mean fidelity in this asymptotic regime for the two cases. We show that within the pointwise estimation approach these limits can be obtained in a rather easy and rapid way. This derivation is based on heuristic arguments that are made rigorous by using van Trees inequalities. The interrelation between the estimation of the purity and the direction of the state is also discussed. In the general case we show that they correspond to independent estimations whereas for the equatorial-plane states this is only true asymptotically.Comment: 19 pages, no figure