Redshift-space limits of bound structures

An exponentially expanding Universe, possibly governed by a cosmological constant, forces gravitationally bound structures to become more and more isolated, eventually becoming causally disconnected from each other and forming so-called "island universes". This new scenario reformulates the question about which will be the largest structures that will remain gravitationally bound, together with requiring a systematic tool that can be used to recognize the limits and mass of these structures from observational data, namely redshift surveys of galaxies. Here we present a method, based on the spherical collapse model and N-body simulations, by which we can estimate the limits of bound structures as observed in redshift space. The method is based on a theoretical criterion presented in a previous paper that determines the mean density contrast that a spherical shell must have in order to be marginally bound to the massive structure within it. Understanding the kinematics of the system, we translated the real-space limiting conditions of this "critical" shell to redshift space, producing a projected velocity envelope that only depends on the density profile of the structure. From it we created a redshift-space version of the density contrast that we called "density estimator", which can be calibrated from N-body simulations for a reasonable projected velocity envelope template, and used to estimate the limits and mass of a structure only from its redshift-space coordinates.Comment: Contains 12 pages, 12 figures and 8 table

Cosmology and Cluster Halo Scaling Relations

We explore the effects of dark matter and dark energy on the dynamical scaling properties of galaxy clusters. We investigate the cluster Faber-Jackson (FJ), Kormendy and Fundamental Plane (FP) relations between the mass, radius and velocity dispersion of cluster size halos in cosmological $N$-body simulations. The simulations span a wide range of cosmological parameters, representing open, flat and closed Universes. Independently of the cosmology, we find that the simulated clusters are close to a perfect virial state and do indeed define a Fundamental Plane. The fitted parameters of the FJ, Kormendy and FP relationships do not show any significant dependence on $\Omega_m$ and/or $\Omega_{\Lambda}$. The one outstanding effect is the influence of $\Omega_{m}$ on the thickness of the Fundamental Plane. Following the time evolution of our models, we find slight changes of FJ and Kormendy parameters in high $\Omega_m$ universe, along with a slight decrease of FP fitting parameters. We also see an initial increase of the FP thickness followed by a convergence to a nearly constant value. The epoch of convergence is later for higher values of $\Omega_m$ while the thickness remains constant in the low $\Omega_m$ $\Lambda$-models. We also find a continuous increase of the FP thickness in the Standard CDM (SCDM) cosmology. There is no evidence that these differences are due to the different power spectrum slope at cluster scales. From the point of view of the FP, there is little difference between clusters that quietly accreted their mass and those that underwent massive mergers. The principal effect of strong mergers is to change significantly the ratio of the half-mass radius $r_{half}$ to the harmonic mean radius $r_h$.Comment: 24 pages, 17 figures, submitted to MNRA

The Limits of Bound Structures in the Accelerating Universe

According to the latest evidence, the Universe is entering an era of exponential expansion, where gravitationally bound structures will get disconnected from each other, forming isolated `island universes'. In this scenario, we present a theoretical criterion to determine the boundaries of gravitationally bound structures and a physically motivated definition of superclusters as the largest bound structures in the Universe. We use the spherical collapse model self-consistently to obtain an analytical condition for the mean density enclosed by the last bound shell of the structure (2.36 times the critical density in the present Universe, assumed to be flat, with 30 per cent matter and 70 per cent cosmological constant, in agreement with the previous, numerical result of Chiueh and He). $N$-body simulations extended to the future show that this criterion, applied at the present cosmological epoch, defines a sphere that encloses $\approx 99.7$ per cent of the particles that will remain bound to the structure at least until the scale parameter of the Universe is 100 times its present value. On the other hand, $(28\pm 13)$ per cent of the enclosed particles are in fact not bound, so the enclosed mass overestimates the bound mass, in contrast with the previous, less rigorous criterion of, e.~g., Busha and collaborators, which gave a more precise mass estimate. We also verify that the spherical collapse model estimate for the radial infall velocity of a shell enclosing a given mean density gives an accurate prediction for the velocity profile of infalling particles, down to very near the centre of the virialized core.Comment: 10 pages, 11 figure

Radio Emission in the Cosmic Web

We explore the possibility of detecting radio emission in the \emph{cosmic web} by analyzing shock waves in the MareNostrum cosmological simulation. This requires a careful calibration of shock finding algorithms in Smoothed-Particle Hydrodynamics simulations, which we present here. Moreover, we identify the elements of the cosmic web, namely voids, walls, filaments and clusters with the use of the SpineWeb technique, a procedure that classifies the structure in terms of its topology. Thus, we are able to study the Mach number distribution as a function of its environment. We find that the median Mach number, for clusters is $\mathcal{M}_{\mathrm{clusters}}\approx1.8$, for filaments is $\mathcal{M}_{\mathrm{filaments}}\approx 6.2$, for walls is $\mathcal{M}_{\mathrm{walls}}\approx 7.5$, and for voids is $\mathcal{M}_{\mathrm{voids}}\approx 18$. We then estimate the radio emission in the cosmic web using the formalism derived in Hoeft & Br\"{u}ggen (2007). We also find that in order to match our simulations with observational data (e.g., NVSS radio relic luminosity function), a fraction of energy dissipated at the shock of $\xi_{\mathrm{e}}=0.0005$ is needed, in contrast with the $\xi_{\mathrm{e}}=0.005$ proposed by Hoeft et al. (2008). We find that 41% of clusters with $M \ge 10^{14} M_{\odot}$ host diffuse radio emission in the form of radio relics. Moreover, we predict that the radio flux from filaments should be $S_{150 MHz}\sim 0.12$ $\mu$Jy at a frequency of 150 MHz.Comment: 19 pages, 17 figures, accepted for publication in MNRAS. Minor changes to tex fil

Future Evolution of Bound Superclusters in an Accelerating Universe

The evolution of marginally bound supercluster-like objects in an accelerating LambdaCDM Universe is followed, by means of cosmological simulations, from the present time to an expansion factor a = 100. The objects are identified on the basis of the binding density criterion introduced by Dunner et al. (2006). superclusters are identified with the ones whose mass M > 10^15 M_sun/h, the most massive one with M ~ 8x10^15 M_sun/h, comparable to the Shapley supercluster. The spatial distribution of the superclusters remains essentially the same after the present epoch, reflecting the halting growth of the Cosmic Web as Lambda gets to dominate the expansion of the Universe. The same trend can be seen in the stagnation of the development of the mass function of virialized haloes and bound objects. The situation is considerably different when looking at the internal evolution, quantified in terms of their shape, compactness and density profile, and substructure in terms of their multiplicity function. We find a continuing evolution from a wide range of triaxial shapes at a = 1 to almost perfect spherical shapes at a = 100. We also find a systematic trend towards a higher concentration. Meanwhile, we see their substructure gradually disappearing, as the surrounding subclumps fall in and merge to form one coherent, virialized system.Comment: 27 pages, 17 figures, accepted for publication in MNRAS, revised version after referee repor

A National Multi-Institutional Analysis of Predictors of Surgical Site Complications and Unplanned Reoperation after Paramedian Forehead Flap Reconstruction

Background: Although postoperative complications of paramedian forehead flap (PMFF) are generally low, surgical site complications and unplanned reoperation can still occur. Recent literature suggests infection to be the most common complication following PMFF reconstruction. This study sought to determine the patient and preoperative factors associated with surgical site complications and unplanned reoperations at a national level. Methods: Patients who underwent PMFF reconstruction from the ACS-NSQIP 2007 - 2019 database were analyzed to determine composite surgical site morbidity and unplanned return to the operating room. Patient and operative factors were also analyzed to assess independent risk factors for surgical site morbidity and unplanned reoperation in the first 30 postoperative days. Results: A total of 1,592 PMFF were analyzed between 2007 and 2019. Of these, 2.7% (43/1592) developed a composite surgical site complication in the first 30 postoperative days. Risk factors for composite surgical site complication included \u3e10% weight loss in the previous 6 months ( Conclusion: Significant weight loss, disseminated cancer, prolonged operation time, low preoperative albumin, and hematocrit are associated with higher PMFF composite surgical site complications. Higher ASA and class 4 wound status are associated with an increased risk of unplanned reoperation

Cystic echinococcosis in dogs and children in the province of Río Negro, Argentina

Fil: Larrieu, Edmundo. Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina; Facultad de Ciencias Veterinarias, Universidad Nacional de Río Negro; Argentina.  Fil: Seleiman, Marcos. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Herrero, Eduardo. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Mujica, Guillermo. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Labanchi, Jose Luis. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Araya, Daniel. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Grizmado, Claudia. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Sepulveda, Luis. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Calabro, Arnoldo. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Talmon, Gabriel. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Crowley, Pablo. Ministerio de Salud, Provincia de Río Negro, Viedma, Argentina; Facultad de Ciencias Veterinarias, Universidad Nacional de Río Negro; Argentina.Fil: Albarracin, Silvina. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Arezo, Marcos. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Parasitología; Argentina.Fil: Volpe, Marcela. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Avila, A. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Perez, Alicia. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Uchiumi, Leonardo. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Salvitti, Juan Carlos. Ministerio de Salud, Provincia de Río Negro; Argentina.Fil: Santillan, Graciela. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Parasitología; Argentina.Cystic echinococcosis (CE) is an endemic disease in the province of Río Negro, Argentina. The control program against CE has developed monitoring surveillance systems. Currently, the coproELISA/Western blot (WB) test is used to determine transmission in livestock farms (epidemiological units or EU) from collected dry field-dispersed dog feces. The objective was to evaluate the prevalence of CE on livestock farms and its relationship with CE cases in children aged 0-14 years. Canine fecal samples were obtained from randomly selected livestock farms and processed by the coproELISA/WB test. Furthermore, new cases in children in the same age group mentioned above were identified. In 278 EU, 571 samples of canine feces were obtained. There were 37 positive samples for coproELISA/WB (6.5%) and the presence of transmission was demonstrated in 37 EU (13.3%). There were no significant differences (p=0.9) with the survey conducted in the period 2003-2004 while there were significant differences (p=0.02) with the EU survey of native populations conducted in 2009-2010. With respect to animal density in the work area, the EU yielding negative results had an average of 2 dogs (SD 2.1) per EU while in the EU having positive results the average was 3 dogs (SD 4.2), showing statistically significant differences (p=0.02). In children under 15 years of age, 12 cases were diagnosed. This study has identified, on average, that the cases of hydatid disease are closer in the positive fields than in the negative fields (p=0.00307).The coproELISA/WB test allowed to identify the dispersion of CE on livestock farms and its relationship with the occurrence of cases in children in 2009-2010