Secondary Star Formation in a Population III Object

We explore the possibility of subsequent star formation after a first star forms in a Pop III object, by focusing on the radiation hydrodynamic (RHD) feedback brought by ionizing photons as well as H2 dissociating photons. For the purpose, we perform three-dimensional RHD simulations, where the radiative transfer of ionizing photons and H2 dissociating photons from a first star is self-consistently coupled with hydrodynamics based on a smoothed particle hydrodynamics method. As a result, it is shown that density peaks above a threshold density can keep collapsing owing to the shielding of H2 dissociating radiation by an H2 shell formed ahead of a D-type ionization front. But, below the threshold density, an M-type ionization front accompanied by a shock propagates, and density peaks are radiation hydrodynamically evaporated by the shock. The threshold density is dependent on the distance from a source star, which is $\approx 10^2 cm^{-3}$ for the source distance of 30pc. Taking into consideration that the extent of a Pop III object is $\approx 100$pc and density peaks within it have the density of $10^{2-4}$cm$^{-3}$, it is concluded that the secondary star formation is allowed in the broad regions in a Pop III object.Comment: 4pages, 2 figures, submitted to Ap

Relation between quantum fluctuations and the performance enhancement of quantum annealing in a nonstoquastic Hamiltonian

We study the relation between quantum fluctuations and the significant enhancement of the performance of quantum annealing in a mean-field Hamiltonian. First-order quantum phase transitions were shown to be reduced to second order by antiferromagnetic transverse interactions in a mean-field-type many-body-interacting Ising spin system in a transverse field, which means an exponential speedup of quantum annealing by adiabatic quantum computation. We investigate if and how quantum effects manifest themselves around these first- and second-order phase transitions to understand if the antiferromagnetic transverse interactions appended to the conventional transverse-field Ising model induce notable quantum effects. By measuring the proximity of the semiclassical spin-coherent state to the true ground state as well as the magnitude of the concurrence representing entanglement, we conclude that significant quantum fluctuations exist around second-order transitions, whereas quantum effects are much less prominent at first-order transitions. Although the location of the transition point can be predicted by the classical picture, system properties near the transition need quantum-mechanical descriptions for a second-order transition but not necessarily for first order. It is also found that quantum fluctuations are large within the ferromagnetic phase after a second-order transition from the paramagnetic phase. These results suggest that the antiferromagnetic transverse interactions induce marked quantum effects, and this fact would be related to closely to the significant enhancement of the performance of quantum annealing.Comment: 9 pages, 8 figure

Extracting Information from Qubit-Environment Correlations

Most works on open quantum systems generally focus on the reduced physical system by tracing out the environment degrees of freedom. Here we show that the qubit distributions with the environment are essential for a thorough analysis, and demonstrate that the way that quantum correlations are distributed in a quantum register is constrained by the way in which each subsystem gets correlated with the environment. For a two-qubit system coupled to a common dissipative environment $\mathcal{E}$, we show how to optimise interqubit correlations and entanglement via a quantification of the qubit-environment information flow, in a process that, perhaps surprisingly, does not rely on the knowledge of the state of the environment. To illustrate our findings, we consider an optically-driven bipartite interacting qubit $AB$ system under the action of $\mathcal{E}$. By tailoring the light-matter interaction, a relationship between the qubits early stage disentanglement and the qubit-environment entanglement distribution is found. We also show that, under suitable initial conditions, the qubits energy asymmetry allows the identification of physical scenarios whereby qubit-qubit entanglement minima coincide with the extrema of the $A\mathcal{E}$ and $B\mathcal{E}$ entanglement oscillations.Comment: 4 figures, 9 page

The Stellar IMF in Very Metal-Deficient Gas

In the context of the star formation through the fragmentation of an extremely metal-deficient protogalactic cloud, the gravitational collapse of filamentary gas clouds is explored with H$_2$ and HD chemistry. It is found by 1D hydrodynamical simulations that the cloud evolution is prescribed mainly by the initial density ($n_0$) and H$_2$ abundance ($x_{\rm H_2,0}$). In particular, it turns out that the evolution of low-density filaments ($n_0 \lesssim 10^5$ cm$^{-3}$) bifurcates at a critical H$_2$ abundance of $x_{\rm H_2,cr}\simeq 3\times 10^{-3}$, beyond which HD cooling overwhelms H$_2$ cooling. The numerical results indicate that the stellar IMF is likely to be double-peaked and deficient in sub-solar mass stars, where the high mass peak of the IMF is around $10M_\odot$ or $10^2M_\odot$, dependently on the initial density and H$_2$ abundance. If the gas in protogalactic clouds is photoionized by UV radiation or shock-heated, the H$_2$ abundance could exceed $x_{\rm H_2,cr}\simeq 3\times 10^{-3}$ by H$^-$ reactions. Then, the high mass peak would be $O(10) M_\odot$.Comment: 4 pages, 1 figure, proceedings of New Quests in Stellar Astrophysics: The link between Stars and Cosmology (eds. M. Chavez, A. Bressan, A. Buzzoni & D. Mayya, to be published by the Kluwer Academic Publishers

New results for hadronic collisions in the framework of the Parton-Based Gribov-Regge Theory

We recently proposed a new approach to high energy nuclear scattering, which treats hadronic collisions in a sophisticated way. Demanding theoretical consistency as a minimal requirement for a realistic model, we provide a solution for the energy conservation, screening problems and identical elementary interactions, the so-called "Parton-Based Gribov-Regge Theory" including enhanced diagrams. We can now present some of our results for SPS and RHIC energies.Comment: 4 pages, 3 figures, To appear in the proceedings of Quark Matter 2002 (QM 2002), Nantes, France, 18-24 Jul 200

Emergence of maximal hidden quantum correlations and its trade-off with the filtering probability in dissipative two-qubit systems

We investigate the behaviour of quantum CHSH-nonlocality, $\rm F_3$-steering, and usefulness for teleportation in an interacting two-qubit dissipative system. We show regimes where these three quantum correlations can be extracted by means of local filtering operations, despite them not being displayed in the bare natural time evolution. Moreover, we show the existence of local hidden state (LHS) and local hidden variable (LHV) models for some states during the dynamics and thus, showing that apparently-useless physical systems could still exhibit quantum correlations, which are hidden from us, but that can still be revealed by means of local filtering operations and therefore, displaying the phenomenon of \emph{hidden} quantum correlations. We furthermore show that there actually exists a trade-off between the amount of quantum correlations which can be extracted and the filtering probability with which such protocol can be implemented. From a theoretical point of view, the existence of such trade-off imposes a fundamental limit to the extraction of quantum correlations by local filtering operations. From a practical point of view on the other hand, the results here presented determine the amount of resources that should be invested in order to extract such maximal hidden quantum correlations.Comment: 15 pages; 5 Figures; Discussion on the trade-off between hidden correlations and their probability of occurrence has been included and improve

Drug delivery applications of three-dimensional printed (3DP) mesoporous scaffolds

Mesoporous materials are structures characterized by a well-ordered large pore system with uniform porous dimensions ranging between 2 and 50 nm. Typical samples are zeolite, carbon molecular sieves, porous metal oxides, organic and inorganic porous hybrid and pillared materials, silica clathrate and clathrate hydrates compounds. Improvement in biochemistry and materials science led to the design and implementation of different types of porous materials ranging from rigid to soft two-dimensional (2D) and three-dimensional (3D) skeletons. The present review focuses on the use of three-dimensional printed (3DP) mesoporous scaffolds suitable for a wide range of drug delivery applications, due to their intrinsic high surface area and high pore volume. In the first part, the importance of the porosity of materials employed for drug delivery application was discussed focusing on mesoporous materials. At the end of the introduction, hard and soft templating synthesis for the realization of ordered 2D/3D mesostructured porous materials were described. In the second part, 3DP fabrication techniques, including fused deposition modelling, material jetting as inkjet printing, electron beam melting, selective laser sintering, stereolithography and digital light processing, electrospinning, and two-photon polymerization were described. In the last section, through recent bibliographic research, a wide number of 3D printed mesoporous materials, for in vitro and in vivo drug delivery applications, most of which relate to bone cells and tissues, were presented and summarized in a table in which all the technical and bibliographical details were reported. This review highlights, to a very cross-sectional audience, how the interdisciplinarity of certain branches of knowledge, as those of materials science and nano-microfabrication are, represent a growing valuable aid in the advanced forum for the science and technology of pharmaceutics and biopharmaceutics

Factores multiplicadores del río Tunjuelo

(Eng) The most important sources of pollution in urban rivers are the sewage system discharges, disturbing the quality and behavior patterns of water resources. The Tunjuelo River is one of the most polluted and important stream from Bogota city, receiving numerous wastewater discharges. Therefore, its sanitation has become one of the main objectives of the environmental authority. However, in order to take action is necessary to understand the water quality behavior specifically loads patterns. This article shows the results of the load multiplier factors for total suspended solids (TSS) and biochemical oxygen demand (BOD), these factors were calculated to understand the behavior of wastewater discharges and at different points on the river. Finally, each discharge has its own characteristics that affect differently the behavior of the river downstream, resulting in a distortion in the flow pattern in most of the sampled points.(Spa) Las fuentes puntuales de contaminación más importantes en los ríos urbanos son las descargas directas del sistema de alcantarillado, además estas afectan la calidad y el patrón de comportamiento de las fuentes hídricas. El río Tunjuelo es una de las corrientes de agua más importante y contaminada de la ciudad de Bogotá, pues recibe una gran cantidad de vertimientos. Por lo anterior su saneamiento se ha convertido en uno de los principales objetivos de la autoridad ambiental, sin embargo, para poder tomar acciones es necesario entender su comportamiento. En el presente artículo se muestran los resultados de los factores multiplicadores de carga para sólidos suspendidos totales (SST) y demanda bioquímica de oxígeno (DBO), puesto que estos son el instrumento económico para el cálculo de la tasa retributiva en Colombia, los cuales fueron calculados para entender el comportamiento de las descargas de aguas residuales y el de diferentes puntos sobre el río. Finalmente, se puede observar que cada descarga tiene características propias que afectan de diferente manera el comportamiento del río aguas abajo, generando como resultado una distorsión en el patrón de flujo de los factores multiplicadores en la mayoría de puntos muestreados

Radiation Hydrodynamical Instabilities in Cosmological and Galactic Ionization Fronts

Ionization fronts, the sharp radiation fronts behind which H/He ionizing photons from massive stars and galaxies propagate through space, were ubiquitous in the universe from its earliest times. The cosmic dark ages ended with the formation of the first primeval stars and galaxies a few hundred Myr after the Big Bang. Numerical simulations suggest that stars in this era were very massive, 25 - 500 solar masses, with H II regions of up to 30,000 light-years in diameter. We present three-dimensional radiation hydrodynamical calculations that reveal that the I-fronts of the first stars and galaxies were prone to violent instabilities, enhancing the escape of UV photons into the early intergalactic medium (IGM) and forming clumpy media in which supernovae later exploded. The enrichment of such clumps with metals by the first supernovae may have led to the prompt formation of a second generation of low-mass stars, profoundly transforming the nature of the first protogalaxies. Cosmological radiation hydrodynamics is unique because ionizing photons coupled strongly to both gas flows and primordial chemistry at early epochs, introducing a hierarchy of disparate characteristic timescales whose relative magnitudes can vary greatly throughout a given calculation. We describe the adaptive multistep integration scheme we have developed for the self-consistent transport of both cosmological and galactic ionization fronts.Comment: 6 pages, 4 figures, accepted for proceedings of HEDLA2010, Caltech, March 15 - 18, 201