Testing the Least Action Principle in an Omega_0=1 Universe

The least action principle (LAP) is a dynamically rigorous method for deriving the history of galaxy orbits. In particular it is an Omega_0 test, predicting current epoch galaxy velocities as a function of position and of the cosmological background. It is most usefully applied to in--falling structures, such as the local group, where its application indicates that the preferred cosmological model is Omega_0 = 0.1 and h=0.75 (h is the Hubble parameter in units of 100 Km s^-1 Mpc^-1). The method assumes that all the mass acts as if it were distributed as the visible galaxies. We test the reliability of the LAP to Local Group-like systems extracted from Omega_0=1 N--body simulations. While the orbits of the galaxies are qualitatively well reconstructed, the LAP systematically underestimates the mass of the system. This failure is attributed to the presence of extended halos weakly clustered around visible galaxies which prevent a large fraction of the group mass from being detected by the LAP technique. We conclude that the LAP method cannot rule out an Omega_0=1 value on the Local Group scale. Better constraints on Omega_0 may be obtained by applying this technique to in--falling systems, such as clusters, containing objects with separations large compared to galaxy sizes.Comment: accepted by APJ, uuencoded-compressed-tarred PostScript file including figures. SISSA Ref. 56/94/

Anisotropy probe of galactic and extra-galactic Dark Matter annihilations

We study the flux and the angular power spectrum of gamma-rays produced by Dark Matter (DM) annihilations in the Milky Way (MW) and in extra-galactic halos. The annihilation signal receives contributions from: a) the smooth MW halo, b) resolved and unresolved substructures in the MW, c) external DM halos at all redshifts, including d) their substructures. Adopting a self-consistent description of local and extra-galactic substructures, we show that the annihilation flux from substructures in the MW dominates over all the other components for angles larger than O(1) degrees from the Galactic Center, unless an extreme prescription is adopted for the substructures concentration. We also compute the angular power spectrum of gamma-ray anisotropies and find that, for an optimistic choice of the particle physics parameters, an interesting signature of DM annihilations could soon be discovered by the Fermi LAT satellite at low multipoles, l<100, where the dominant contribution comes from MW substructures with mass M>10^4 solar masses. For the substructures models we have adopted, we find that the contribution of extra-galactic annihilations is instead negligible at all scales.Comment: 14 pages, 7 figure

Euclid preparation: XV. Forecasting cosmological constraints for the EuclidEuclid and CMB joint analysis

The combination and cross-correlation of the upcoming Euclid data with cosmic microwave background (CMB) measurements is a source of great expectation since it will provide the largest lever arm of epochs, ranging from recombination to structure formation across the entire past light cone. In this work, we present forecasts for the joint analysis of Euclid and CMB data on the cosmological parameters of the standard cosmological model and some of its extensions. This work expands and complements the recently published forecasts based on Euclid-specific probes, namely galaxy clustering, weak lensing, and their cross-correlation. With some assumptions on the specifications of current and future CMB experiments, the predicted constraints are obtained from both a standard Fisher formalism and a posterior-fitting approach based on actual CMB data. Compared to a Euclid-only analysis, the addition of CMB data leads to a substantial impact on constraints for all cosmological parameters of the standard Λ-cold-dark-matter model, with improvements reaching up to a factor of ten. For the parameters of extended models, which include a redshift-dependent dark energy equation of state, non-zero curvature, and a phenomenological modification of gravity, improvements can be of the order of two to three, reaching higher than ten in some cases. The results highlight the crucial importance for cosmological constraints of the combination and cross-correlation of Euclid probes with CMB data

Studying the Warm Hot Intergalactic Medium in emission: a reprise

The Warm-Hot Intergalactic Medium (WHIM) is believed to host a significant fraction of the ``missing baryons'' in the nearby Universe. Its signature has been detected in the X-ray absorption spectra of distant quasars. However, its detection in emission, that would allow us to study the WHIM in a systematic way, is still lacking. Motivated by the possibility to perform these studies with next generation integral field spectrometers, and thanks to the availability of a large suite of state-of-the-art hydrodynamic simulations -- the CAMELS suite -- we study here in detail the emission properties of the WHIM and the possibility to infer its physical properties with upcoming X-ray missions like Athena. We focused on the two most prominent WHIM emission lines, the OVII triplet and the OVIII singlet, and build line surface brightness maps in a lightcone, mimicking a data cube generated through integral field spectroscopy. We confirm that detectable WHIM emission, even with next generation instruments, is largely associated to galaxy-size dark matter halos and that the WHIM properties evolve little from $z\simeq0.5$ to now. Some characteristics of the WHIM, like the line number counts as a function of their brightness, depend on the specific hydrodynamic simulation used, while others, like the WHIM clustering properties, are robust to this aspect. The large number of simulations available in the CAMELS datasets allows us to assess the sensitivity of the WHIM properties to the background cosmology and to the energy feedback mechanisms regulated by AGN and stellar activity. [ABRIDGED]Comment: 23 pages, 17 figures, 3 table

A prototype of fine granularity lead-scintillating fiber calorimeter with imaging read out

The construction and tests performed on a smal prototype of lead-scintillating fiber calorimeter instrumented with multianode photomultipliers are reported. The prototype is 15 cm wide, 15 radiation lenghts deep and is made of 200 layers of 50 cm long fibers. One side of the calorimeter has been instrumented with an array of 3 × 5 multianode R8900-M16 Hamamatsu photomultipliers, each segmented with a matrix of 4 × 4 anodes. The read-out granularity is 240 pixels 11 × 11 mm 2 reading about 64 fibers each. They are interfaced to the 6 × 6 mm 2 pixelled photocade with truncated pyramid light guides made of BC-800 plastic, UV transparent. Moreover each photomultiplier provides also the OR information of the last 12 dynodes. This information can be useful for trigger purposes. The response of the individual anodes, their relative gain and cross-talk has been measured with a 404 nm picosecond laser illuminating only a few fibers on the opposite side of the read-out. We also present first results of the calorimeter response to cosmic rays and electron beam data collected at BTF facility in Frascati

Choroidal Imaging Using Spectral-Domain Optical Coherence Tomography

Author Manuscript received 2012 June 22.Background: A structurally and functionally normal choroidal vasculature is essential for retinal function. Therefore, a precise clinical understanding of choroidal morphology should be important for understanding many retinal and choroidal diseases. Methods: PUBMED ( http://www.ncbi.nlm.nih.gov/site...) was used for most of the literature search for this article. The criterion for inclusion of an article in the references for this review was that it included materials about both the clinical and the basic properties of choroidal imaging using spectral-domain optical coherence tomography. Results: Recent reports show successful examination and accurate measurement of choroidal thickness in normal and pathologic states using spectral-domain optical coherence tomography systems. This review focuses on the principles of the new technology that make choroidal imaging using optical coherence tomography possible and on the changes that subsequently have been documented to occur in the choroid in various diseases. Additionally, it outlines future directions in choroidal imaging. Conclusion: Optical coherence tomography is now proven to be an effective noninvasive tool to evaluate the choroid and to detect choroidal changes in pathologic states. Additionally, choroidal evaluation using optical coherence tomography can be used as a parameter for diagnosis and follow-up.Research to Prevent Blindness, Inc. (United States) (Unrestricted Grant)National Institutes of Health (U.S.) (Contract RO1-EY11289-25)National Institutes of Health (U.S.) (Contract R01-EY13178-10)National Institutes of Health (U.S.) (Contract R01-EY013516-07)National Institutes of Health (U.S.) (Contract R01-EY019029-02)United States. Air Force Office of Scientific Research (Grant FA9550-10-1-0551)United States. Air Force Office of Scientific Research (FA9550-10-1-0063

Utilities Substations in Smart District Heating Networks

Abstract In the last decades the concept of distributed generation – i.e. the installation of (electrical and/or thermal) energy production systems at the final users – was born and found gradually increasing diffusion. For what concerns the electrical production, the distributed generation systems are directly connected to the National Electricity Transmission Grid, allowing a bidirectional energy flux at the utilities and giving rise to the so-called smart grid. In this scenario and considering that, even thanks to the direction taken by European regulations, in the European territory there is already a large number of thermal power generation's distributed systems (e.g. solar thermal panels), in the near future the concept of smart grid could be extended to the heat sector, especially in relation to District Heating Networks (DHNs). As a consequence, with the aim of analyzing the penetration of this type of networks, several possible layouts for the exchange utilities' substation have been developed and will be presented in this study. Such layouts allow to optimize thermal exchange, as a function of network design temperatures (for both the supply and the return), of utilities' thermal power requirement and depending on the characteristics of the production system

Analysis of Normal Peripapillary Choroidal Thickness via Spectral Domain Optical Coherence Tomography

Purpose To analyze the normal peripapillary choroidal thickness utilizing a commercial spectral domain optical coherence tomography (OCT) device and determine the intergrader reproducibility of this method. Design Retrospective, noncomparative, noninterventional case series. Participants Thirty-six eyes of 36 normal patients seen at the New England Eye Center between April and September 2010. Methods All patients underwent high-definition scanning with the Cirrus HD-OCT. Two raster scans were obtained per eye, a horizontal and a vertical scan, both of which were centered at the optic nerve. Two independent graders individually measured the choroidal thickness. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid–scleral junction at 500-μm intervals away from the optic nerve in the superior, inferior, nasal, and temporal quadrants. Statistical analysis was conducted to compare mean choroidal thicknesses. Intergrader reproducibility was assessed by intraclass correlation coefficient and Pearson's correlation coefficient. Average choroidal thickness in each quadrant was compared with retinal nerve fiber layer (RNFL) thickness in their respective quadrants. Main Outcome Measures Peripapillary choroidal thickness, intraclass coefficient, and Pearson's correlation coefficient. Results The peripapillary choroid in the inferior quadrant was significantly thinner compared with all other quadrants (P<0.001). None of the other quadrants were significantly different from each other in terms of thickness. The inferior peripapillary choroid was significantly thinner compared with all other quadrants at all distances measured away from the optic nerve (P<0.001). Generally, the peripapillary choroid increases in thickness the farther it was away from the optic nerve and eventually approaching a plateau. The intraclass correlation coefficient ranged from 0.62 to 0.93 and Pearson's correlation coefficient ranged from 0.74 to 0.95 (P<0.001). Neither RNFL thickness nor average age was significantly correlated with average choroidal thickness. Conclusions Manual segmentation of the peripapillary choroidal thickness is reproducible between graders, suggesting that this method is accurate. The inferior peripapillary choroid was significantly thinner than all other quadrants (P<0.001).Research to Prevent Blindness, Inc. (United States)National Institutes of Health (U.S.) (RO1-EY11289-24)National Institutes of Health (U.S.) (R01-EY13178-10)National Institutes of Health (U.S.) (R01-EY013516-07)United States. Air Force Office of Scientific Research (FA9550-07-1-0101)United States. Air Force Office of Scientific Research (FA9550-07-1-0014

Comparison of the ENEAR Peculiar Velocities with the PSCz Gravity Field

We present a comparison between the peculiar velocity field measured from the ENEAR all-sky Dn−σ catalogue and that derived from the galaxy distribution of the IRAS Point Source Catalog Redshift Survey (PSCz). The analysis is based on a modal expansion of these data in redshift space by means of spherical harmonics and Bessel functions. The effective smoothing scale of the expansion is almost linear with redshift reaching 1500kms−1 at 3000kms−1. The general flow patterns in the filtered ENEAR and PSCz velocity fields agree well within 6000kms−1, assuming a linear biasing relation between the mass and the PSCz galaxies. The comparison allows us to determine the parameter β = Ω0.6 / b, where Ω is the cosmological density parameter and b is the linear biasing factor. A likelihood analysis of the ENEAR and PSCz modes yields β = 0.5 ± 0.1, in good agreement with values obtained from Tully-Fisher surveys