Collapse of Primordial Clouds

We present here studies of collapse of purely baryonic Population III objects with masses ranging from $10M_\odot$ to $10^6M_\odot$. A spherical Lagrangian hydrodynamic code has been written to study the formation and evolution of the primordial clouds, from the beginning of the recombination era ($z_{rec} \sim 1500$) until the redshift when the collapse occurs. All the relevant processes are included in the calculations, as well as, the expansion of the Universe. As initial condition we take different values for the Hubble constant and for the baryonic density parameter (considering however a purely baryonic Universe), as well as different density perturbation spectra, in order to see their influence on the behavior of the Population III objects evolution. We find, for example, that the first mass that collapses is $8.5\times10^4M_\odot$ for $h=1$, $\Omega=0.1$ and $\delta_i={\delta\rho / \rho}=(M / M_o)^{-1/3}(1+z_{rec})^{-1}$ with the mass scale $M_o=10^{15}M_\odot$. For $M_o=4\times10^{17}M_\odot$ we obtain $4.4\times10^{4}M_\odot$ for the first mass that collapses. The cooling-heating and photon drag processes have a key role in the collapse of the clouds and in their thermal history. Our results show, for example, that when we disregard the Compton cooling-heating, the collapse of the objects with masses $>8.5\times10^4M_\odot$ occurs earlier. On the other hand, disregarding the photon drag process, the collapse occurs at a higher redshift.Comment: 10 pages, MN plain TeX macros v1.6 file, 9 PS figures. Also available at http://www.iagusp.usp.br/~oswaldo (click "OPTIONS" and then "ARTICLES"). MNRAS in pres

Collapse of Primordial Clouds II. The Role of Dark Matter

In this article we extend the study performed in our previous article on the collapse of primordial objects. We here analyze the behavior of the physical parameters for clouds ranging from $10^7M_\odot$ to $10^{15}M_\odot$. We studied the dynamical evolution of these clouds in two ways: purely baryonic clouds and clouds with non-baryonic dark matter included. We start the calculations at the beginning of the recombination era, following the evolution of the structure until the collapse (that we defined as the time when the density contrast of the baryonic matter is greater than $10^4$). We analyze the behavior of the several physical parameters of the clouds (as, e.g., the density contrast and the velocities of the baryonic matter and the dark matter) as a function of time and radial position in the cloud. In this study all physical processes that are relevant to the dynamical evolution of the primordial clouds, as for example photon-drag (due to the cosmic background radiation), hydrogen molecular production, besides the expansion of the Universe, are included in the calculations. In particular we find that the clouds, with dark matter, collapse at higher redshift when we compare the results with the purely baryonic models. As a general result we find that the distribution of the non-baryonic dark matter is more concentrated than the baryonic one. It is important to stress that we do not take into account the putative virialization of the non-baryonic dark matter, we just follow the time and spatial evolution of the cloud solving its hydrodynamical equations. We studied also the role of the cooling-heating processes in the purely baryonic clouds.Comment: 8 pages, MN plain TeX macros v1.6 file, 13 PS figures. Also available at http://www.iagusp.usp.br/~oswaldo (click "OPTIONS" and then "ARTICLES"). MNRAS in pres

Spatially-Correlated Microstructure and Superconductivity in Polycrystalline Boron-Doped Diamond

Scanning tunneling spectroscopies are performed below 100~mK on nano-crystalline boron-doped diamond films characterized by Transmission Electron Microscopy and transport measurements. We demonstrate a strong correlation between the local superconductivity strength and the granular structure of the films. The study of the spectral shape, amplitude and temperature dependence of the superconductivity gap enables us to differentiate intrinsically superconducting grains that follow the BCS model, from grains showing a different behavior involving the superconducting proximity effect

Travel of studies: cities of João Pessoa, Maceio, Natal and Recife: a look on the urban space and brazilian architectural production

Ponencia presentada a Session 8: Dimensiones psicosociales de la arquitectura y el urbanismo / Psycological dimensions of architecture and planningThis article aims to present the methodology and the final results of the elective course “Travel of Studies” which belongs to the new pedagogical project from the Architecture and Urbanism course at the University Federal of Pernambuco. It was offered for the first time in 2013.The discipline was organized to occur in four long weekends through visits of four capitals of the Northeast of Brazil: Recife, João Pessoa, Natal and Maceió. The purpose was to allow the students to apprehend the cities through four axis: intervention in historical center (axis 1), production of urban space (axis 2), production of coastline space (axis 3) and contemporary architecture (axis 4). After the four visits were complete, we prepared a poster with the comparison of the cities based on the identification of the similarities and differences of each axis we have studied

The Caregiver Support Ratio in Europe: Estimating the Future of Potentially (Un)Available Caregivers

The caregiver support ratio (CSR) is defined as the number of potential caregivers aged 45–64 years, the most common caregiving age range, for each person aged 80+, the subgroup of older adults most at risk of needing long-term services and support. This study uses data from the CENSUS HUB database and from the UN database to calculate the current (last year available: 2011) and projected (2020, 2030, 2040 and 2050) CSR for a group of European countries. Mediterranean countries, France, Belgium, and Sweden presented the lowest CSR (5:1) in 2011. The countries with the highest CSR were Slovakia (9:1) and Ireland, Poland, Cyprus, and Malta (8:1). The estimated CSR is expected to progressively decline from 6:1 (2011) to 2:1 (2050) for all countries. Although differences in the CSR exist between countries, the number of people aged 45–64 who are available to care for each person aged 80+ will decrease uniformly in the coming decades. Cross-national challenges for gerontological social policies and healthcare provision are expected due to the increasing demand for long-term care among the oldest population.This work was partially supported by National Funds through Fundação para a Ciência e a Tecnologia (FCT) within the CINTESIS R&D Unit (reference UIDB/4255/2020). Some information from this study was presented at the 2019 Annual Meeting of the Gerontological Society of America

The conservation of energy-momentum and the mass for the graviton

In this work we give special attention to the bimetric theory of gravitation with massive gravitons proposed by Visser in 1998. In his theory, a prior background metric is necessary to take in account the massive term. Although in the great part of the astrophysical studies the Minkowski metric is the best choice to the background metric, it is not possible to consider this metric in cosmology. In order to keep the Minkowski metric as background in this case, we suggest an interpretation of the energy-momentum conservation in Visser's theory, which is in accordance with the equivalence principle and recovers naturally the special relativity in the absence of gravitational sources. Although we do not present a general proof of our hypothesis we show its validity in the simple case of a plane and dust-dominated universe, in which the `massive term' appears like an extra contribution for the energy density.Comment: 9 pages, accepted for publishing in GR

Generalized Involution Models for Wreath Products

We prove that if a finite group $H$ has a generalized involution model, as defined by Bump and Ginzburg, then the wreath product $H \wr S_n$ also has a generalized involution model. This extends the work of Baddeley concerning involution models for wreath products. As an application, we construct a Gelfand model for wreath products of the form $A \wr S_n$ with $A$ abelian, and give an alternate proof of a recent result due to Adin, Postnikov, and Roichman describing a particularly elegant Gelfand model for the wreath product \ZZ_r \wr S_n. We conclude by discussing some notable properties of this representation and its decomposition into irreducible constituents, proving a conjecture of Adin, Roichman, and Postnikov's.Comment: 29 page

Can black hole MACHO binaries be detected by the Brazilian spherical antenna?

Different studies show that dark matter of non-baryonic origin might exist. There have been experimental evidences that at least one form of dark matter has been detected through microlensing effects. This form of dark matter is named MACHOs (Massive Astrophysical Compact Halo Objects). The MACHO collaboration estimated that the masses of these objects are to be in the range 0.15-0.95 solar masses, where the most probable mass is of 0.5 solar masses. Some authors argue that MACHOs could be black holes, and that they could form binary systems, BHMACHO binaries. As is well known binary systems are sources of gravitational waves. The Brazilian spherical antenna will operate in the frequency band of 3.0-3.4 kHz, sensitive to binaries of a pair of 0.5 solar mass black holes just before coalescing. In the present work we study the detectability of these putative BHMACHO binaries by the Brazilian spherical antenna Mario Schenberg.Comment: 7 pages, 2 figure