Topological defects: A problem for cyclic universes?

We study the behaviour of cosmic string networks in contracting universes, and discuss some of their possible consequences. We note that there is a fundamental time asymmetry between defect network evolution for an expanding universe and a contracting universe. A string network with negligible loop production and small-scale structure will asymptotically behave during the collapse phase as a radiation fluid. In realistic networks these two effects are important, making this solution only approximate. We derive new scaling solutions describing this effect, and test them against high-resolution numerical simulations. A string network in a contracting universe, together with the gravitational radiation background it has generated, can significantly affect the dynamics of the universe both locally and globally. The network can be an important source of radiation, entropy and inhomogeneity. We discuss the possible implications of these findings for bouncing and cyclic cosmological models.Comment: 11 RevTeX 4 pages, 6 figures; version to appear in Phys. Rev.

Coupled oscillators as models of phantom and scalar field cosmologies

We study a toy model for phantom cosmology recently introduced in the literature and consisting of two oscillators, one of which carries negative kinetic energy. The results are compared with the exact phase space picture obtained for similar dynamical systems describing, respectively, a massive canonical scalar field conformally coupled to the spacetime curvature, and a conformally coupled massive phantom. Finally, the dynamical system describing exactly a minimally coupled phantom is studied and compared with the toy model.Comment: 18 pages, LaTeX, to appear in Physical Review

Categorizing Different Approaches to the Cosmological Constant Problem

We have found that proposals addressing the old cosmological constant problem come in various categories. The aim of this paper is to identify as many different, credible mechanisms as possible and to provide them with a code for future reference. We find that they all can be classified into five different schemes of which we indicate the advantages and drawbacks. Besides, we add a new approach based on a symmetry principle mapping real to imaginary spacetime.Comment: updated version, accepted for publicatio

J-PLUS: The javalambre photometric local universe survey

ABSTRACT: TheJavalambrePhotometric Local UniverseSurvey (J-PLUS )isanongoing 12-band photometricopticalsurvey, observingthousands of squaredegrees of theNorthernHemispherefromthededicated JAST/T80 telescope at the Observatorio Astrofísico de Javalambre (OAJ). The T80Cam is a camera with a field of view of 2 deg2 mountedon a telescopewith a diameter of 83 cm, and isequippedwith a uniquesystem of filtersspanningtheentireopticalrange (3500–10 000 Å). Thisfiltersystemis a combination of broad-, medium-, and narrow-band filters, optimallydesigned to extracttherest-framespectralfeatures (the 3700–4000 Å Balmer break region, Hδ, Ca H+K, the G band, and the Mg b and Ca triplets) that are key to characterizingstellartypes and delivering a low-resolutionphotospectrumforeach pixel of theobservedsky. With a typicaldepth of AB ∼21.25 mag per band, thisfilter set thusallowsforanunbiased and accuratecharacterization of thestellarpopulation in our Galaxy, itprovidesanunprecedented 2D photospectralinformationforall resolved galaxies in the local Universe, as well as accuratephoto-z estimates (at the δ z/(1 + z)∼0.005–0.03 precisionlevel) formoderatelybright (up to r ∼ 20 mag) extragalacticsources. Whilesomenarrow-band filters are designedforthestudy of particular emissionfeatures ([O II]/λ3727, Hα/λ6563) up to z < 0.017, theyalsoprovidewell-definedwindowsfortheanalysis of otheremissionlines at higherredshifts. As a result, J-PLUS has thepotential to contribute to a widerange of fields in Astrophysics, both in thenearbyUniverse (MilkyWaystructure, globular clusters, 2D IFU-likestudies, stellarpopulations of nearby and moderate-redshiftgalaxies, clusters of galaxies) and at highredshifts (emission-line galaxies at z ≈ 0.77, 2.2, and 4.4, quasi-stellarobjects, etc.). Withthispaper, wereleasethefirst∼1000 deg2 of J-PLUS data, containingabout 4.3 millionstars and 3.0 milliongalaxies at r <  21mag. With a goal of 8500 deg2 forthe total J-PLUS footprint, thesenumbers are expected to rise to about 35 millionstars and 24 milliongalaxiesbytheend of thesurvey.Funding for the J-PLUS Project has been provided by the Governments of Spain and Aragón through the Fondo de Inversiones de Teruel, the Spanish Ministry of Economy and Competitiveness (MINECO; under grants AYA2017-86274-P, AYA2016-77846-P, AYA2016-77237-C3-1-P, AYA2015-66211-C2-1-P, AYA2015-66211-C2-2, AYA2012-30789, AGAUR grant SGR-661/2017, and ICTS-2009-14), and European FEDER funding (FCDD10-4E-867, FCDD13-4E-2685

Neuropathology in cats experimentally infected with feline immunodeficiency virus: A morphological, immunocytochemical and morphometric study

Neuropathological changes have been described associated with feline immunodeficiency virus (FIV) infection. The objective of our study was to characterize the lesions found in the brain and spinal cord of experimentally FIV-infected cats and to quantify, by morphometric analysis, the intensity of gliosis found in these subjects at different time post infection (pi). The brains and spinal cords appeared grossly normal. Gray matter of cortical and subcortical structures showed a moderate to pronounced gliosis particularly in all cerebral cortex and hippocampus. Morphometric analysis demonstrated that GFAP immunoreactivity was markedly higher in infected animals. Gliosis was present 15 days pi and did not appear to progress during the infection, whereas neuronal changes when present were observed only in long-term infected animals (15-23 months pi). In a large proportion of infected cats a diffuse gliosis of white matter and vacuolar myelinopathy was also present. Despite some discrepancies observed between neuropathological changes in FIV-infected animals and HIV-infected individuals, the presence in the cerebral cortex of cats with FIV infection of alterations similar to those observed in AIDS patients demonstrates that FIV is an interesting animal model particularly that may be useful for clarifying the pathogenesis of neuropathological changes associated with HIV infection

Increased IgG1, IFN-gamma, TNF-alpha and IL-6 responses to Mycobacterium tuberculosis antigens in patients with Tuberculosis are lower after chemotherapy

Detection of specific antibodies may represent an additional tool in diagnosis of tuberculosis (TB). Herein, levels of serum IgG antibodies against early secreted antigenic target (ESAT-6), culture filtrate antigen-10 (CFP-10) and 16kDa Mycobacterium tuberculosis antigens were measured in 33 active pulmonary TB patients (0M-TB), in 47 patients after 1-3 months of treatment (3M-TB) and in 22 patients who had completed 6 months of chemotherapy (6M-TB). The control group consisted of 38 BCG-vaccinated healthy controls (HC). In addition, IFN-gamma, tumor necrosis factor (TNF)-alpha, IL-6, IL-2, IL-4 and IL-10 production in PBMC cultures from 20 patients were measured following stimulation with the M. tuberculosis-specific fusion protein ESAT-6/CFP-10. Elevated levels of IgG against ESAT-6, CFP-10 and 16kDa antigens were detected in 0M-TB and 3M-TB patients in comparison to the HC and 6M-TB groups. Receiver operating characteristic analysis indicated sensitivity of 85, 94 and 61% and specificity of 89, 87 and 89% for serum IgG against ESAT-6, CFP-10 and 16kDa, respectively. A predominant IgG1 response to ESAT-6 and CFP-10 was observed in 0M-TB patients, together with ESAT-6/CFP-10-specific IFN-gamma, TNF-alpha and IL-6 that were produced at lower levels in the 6M-TB group. These data indicate that a T(h)1 phenotype against early phase Mtb antigens appears to be dominant in the peripheral blood of patients with active pulmonary TB that is reduced after chemotherapy. Taken together, ESAT-6/CFP-10 cytokine tests together with detecting IgG antibodies specific to ESAT-6 and CFP-10 may be the useful TB disease biomarkers in monitoring treatment success.Immunogenetics and cellular immunology of bacterial infectious disease

Increased IgG1, IFN-gamma, TNF-alpha and IL-6 responses to Mycobacterium tuberculosis antigens in patients with Tuberculosis are lower after chemotherapy

Detection of specific antibodies may represent an additional tool in diagnosis of tuberculosis (TB). Herein, levels of serum IgG antibodies against early secreted antigenic target (ESAT-6), culture filtrate antigen-10 (CFP-10) and 16kDa Mycobacterium tuberculosis antigens were measured in 33 active pulmonary TB patients (0M-TB), in 47 patients after 1-3 months of treatment (3M-TB) and in 22 patients who had completed 6 months of chemotherapy (6M-TB). The control group consisted of 38 BCG-vaccinated healthy controls (HC). In addition, IFN-gamma, tumor necrosis factor (TNF)-alpha, IL-6, IL-2, IL-4 and IL-10 production in PBMC cultures from 20 patients were measured following stimulation with the M. tuberculosis-specific fusion protein ESAT-6/CFP-10. Elevated levels of IgG against ESAT-6, CFP-10 and 16kDa antigens were detected in 0M-TB and 3M-TB patients in comparison to the HC and 6M-TB groups. Receiver operating characteristic analysis indicated sensitivity of 85, 94 and 61% and specificity of 89, 87 and 89% for serum IgG against ESAT-6, CFP-10 and 16kDa, respectively. A predominant IgG1 response to ESAT-6 and CFP-10 was observed in 0M-TB patients, together with ESAT-6/CFP-10-specific IFN-gamma, TNF-alpha and IL-6 that were produced at lower levels in the 6M-TB group. These data indicate that a T(h)1 phenotype against early phase Mtb antigens appears to be dominant in the peripheral blood of patients with active pulmonary TB that is reduced after chemotherapy. Taken together, ESAT-6/CFP-10 cytokine tests together with detecting IgG antibodies specific to ESAT-6 and CFP-10 may be the useful TB disease biomarkers in monitoring treatment success