New constraints on primordial gravitational waves from Planck 2015

We show that the new precise measurements of Cosmic Microwave Background (CMB) temperature and polarization anisotropies made by the Planck satellite significantly improves previous constraints on the cosmic gravitational waves background (CGWB) at frequencies $f>10^{-15}$ Hz. On scales smaller than the horizon at the time of decoupling, primordial gravitational waves contribute to the total radiation content of the Universe. Considering adiabatic perturbations, CGWB affects temperature and polarization CMB power spectra and matter power spectrum in a manner identical to relativistic particles. Considering the latest Planck results we constrain the CGWB energy density to $\Omega_{\rm gw} h^2 <1.7\times 10^{-6}$ at 95\% CL. Combining CMB power spectra with lensing, BAO and primordial Deuterium abundance observations, we obtain $\Omega_{\rm gw} h^2 <1.2\times 10^{-6}$ at 95\% CL, improving previous Planck bounds by a factor 3 and the recent direct upper limit from the LIGO and VIRGO experiments a factor 2. A combined analysis of future satellite missions as COrE and EUCLID could improve current bound by more than an order of magnitude.Comment: 9 pages, 1 figure, matching the version published on PL

Cosmological constraints on the neutron lifetime

We derive new constraints on the neutron lifetime based on the recent Planck 2015 observations of temperature and polarization anisotropies of the CMB. Under the assumption of standard Big Bang Nucleosynthesis, we show that Planck data constrains the neutron lifetime to $\tau_n=(907 \pm 69) \, [\text{s}]$ at $68 \%$ c.l.. Moreover, by including the direct measurements of primordial Helium abundance of Aver et al. (2015) and Izotov et al. (2014), we show that cosmological data provide the stringent constraints $\tau_n=(875 \pm 19) \, [\text{s}]$ and $\tau_n=(921 \pm 11) \, [\text{s}]$ respectively. The latter appears to be in tension with neutron lifetime value quoted by the Particle Data Group ($\tau_n=(880.3 \pm 1.1) \, [\text{s}]$). Future CMB surveys as COrE+, in combination with a weak lensing survey as EUCLID, could constrain the neutron lifetime up to a $\sim 6 \, [\text{s}]$ precision.Comment: 13 pages, 3 figures. Matching JCAP accepted versio

Breaking Be: a sterile neutrino solution to the cosmological lithium problem

The possibility that the so-called "lithium problem", i.e. the disagreement between the theoretical abundance predicted for primordial $^7$Li assuming standard nucleosynthesis and the value inferred from astrophysical measurements, can be solved through a non-thermal BBN mechanism has been investigated by several authors. In particular, it has been shown that the decay of a MeV-mass particle, like, e.g., a sterile neutrino, decaying after BBN not only solves the lithium problem, but also satisfies cosmological and laboratory bounds, making such a scenario worth to be investigated in further detail. In this paper, we constrain the parameters of the model with the combination of current data, including Planck 2015 measurements of temperature and polarization anisotropies of the CMB, FIRAS limits on spectral distortions, astrophysical measurements of primordial abundances and laboratory constraints. We find that a sterile neutrino with mass $M_S=4.35_{-0.17}^{+0.13}\,MeV$ (at $95\%$ c.l.), a decay time $\tau_S=1.8_{-1.3}^{+2.5}\cdot 10^5\,s$ (at $95\%$ c.l.) and an initial density $\bar{n}_S/\bar{n}_{cmb}=1.7_{-0.6}^{+3.5}\cdot 10^{-4}$ (at $95\%$ c.l.) in units of the number density of CMB photons, perfectly accounts for the difference between predicted and observed $^7$Li primordial abundance. This model also predicts an increase of the effective number of relativistic degrees of freedom at the time of CMB decoupling $\Delta N_{eff}^{cmb}\equiv N_{eff}^{cmb}-3.046=0.34_{-0.14}^{+0.16}$ at $95\%$ c.l.. The required abundance of sterile neutrinos is incompatible with the standard thermal history of the Universe, but could be realized in a low reheating temperature scenario. We provide forecasts for future experiments finding that the combination of measurements from the COrE+ and PIXIE missions will allow to significantly reduce the permitted region for the sterile lifetime and density.Comment: 28 pages, 13 figures, 4 tables, matching the published versio

Constraints on the early and late integrated Sachs-Wolfe effects from the Planck 2015 cosmic microwave background anisotropies in the angular power spectra

The Integrated Sachs-Wolfe (ISW) effect predicts additional anisotropies in the Cosmic MicrowaveBackground due to time variation of the gravitational potential when the expansion of the universeis not matter dominated. The ISW effect is therefore expected in the early universe, due to thepresence of relativistic particles at recombination, and in the late universe, when dark energy startsto dominate the expansion. Deviations from the standard picture can be parameterized byAeISWandAlISW, which rescale the overall amplitude of the early and late ISW effects. Analyzing themost recent CMB temperature spectra from the Planck 2015 release, we detect the presence of theearly ISW at high significance withAeISW= 1.06±0.04 at 68% CL and an upper limit for thelate ISW ofAlISW<1.1 at 95% CL. The inclusion of the recent polarization data from the Planckexperiment erases such 1.5σhint forAeISW6= 1. When considering the recent detections of the lateISW coming from correlations between CMB temperature anisotropies and weak lensing, a value ofAlISW= 0.85±0.21 is predicted at 68% CL, showing a 4σevidence. We discuss the stability of ourresult in the case of an extra relativistic energy component parametrized by the effective neutrinonumberNeffand of a CMB lensing amplitudeA

Blue Gravity Waves from BICEP2 ?

We present new constraints on the spectral index n_T of tensor fluctuations from the recent data obtained by the BICEP2 experiment. We found that the BICEP2 data alone slightly prefers a positive, "blue", spectral index with n_T=1.36\pm0.83 at 68 % c.l.. However, when a TT prior on the tensor amplitude coming from temperature anisotropy measurements is assumed we get n_T=1.67\pm0.53 at 68 % c.l., ruling out a scale invariant $n_T=0$ spectrum at more than three standard deviations. These results are at odds with current bounds on the tensor spectral index coming from pulsar timing, Big Bang Nucleosynthesis, and direct measurements from the LIGO experiment. Considering only the possibility of a "red", n_T<0 spectral index we obtain the lower limit n_T > -0.76 at 68 % c.l. (n_T>-0.09 when a TT prior is included).Comment: 3 Pages, 4 Figure

Determining the dynamics of influenza transmission by age

Background: It is widely accepted that influenza transmission dynamics vary by age; however methods to quantify the reproductive number by age group are limited. We introduce a simple method to estimate the reproductive number by modifying the method originally proposed by Wallinga and Teunis and using existing information on contact patterns between age groups. We additionally perform a sensitivity analysis to determine the potential impact of differential healthcare seeking patterns by age. We illustrate this method using data from the 2009 H1N1 Influenza pandemic in Gauteng Province, South Africa. Results: Our results are consistent with others in showing decreased transmission with age. We show that results can change markedly when we make the account for differential healthcare seeking behaviors by age. Conclusions: We show substantial heterogeneity in transmission by age group during the Influenza A H1N1 pandemic in South Africa. This information can greatly assist in targeting interventions and implementing social distancing measures

Estimating the reproductive number in the presence of spatial heterogeneity of transmission patterns

Background: Estimates of parameters for disease transmission in large-scale infectious disease outbreaks are often obtained to represent large groups of people, providing an average over a potentially very diverse area. For control measures to be more effective, a measure of the heterogeneity of the parameters is desirable. Methods: We propose a novel extension of a network-based approach to estimating the reproductive number. With this we can incorporate spatial and/or demographic information through a similarity matrix. We apply this to the 2009 Influenza pandemic in South Africa to understand the spatial variability across provinces. We explore the use of five similarity matrices to illustrate their impact on the subsequent epidemic parameter estimates. Results: When treating South Africa as a single entity with homogeneous transmission characteristics across the country, the basic reproductive number, R0, (and imputation range) is 1.33 (1.31, 1.36). When fitting a new model for each province with no inter-province connections this estimate varies little (1.23-1.37). Using the proposed method with any of the four similarity measures yields an overall R0 that varies little across the four new models (1.33 to 1.34). However, when allowed to vary across provinces, the estimated R0 is greater than one consistently in only two of the nine provinces, the most densely populated provinces of Gauteng and Western Cape. Conclusions: Our results suggest that the spatial heterogeneity of influenza transmission was compelling in South Africa during the 2009 pandemic. This variability makes a qualitative difference in our understanding of the epidemic. While the cause of this fluctuation might be partially due to reporting differences, there is substantial evidence to warrant further investigation

Angiostrongylus vasorum: Epidemiological, clinical and histopathological insights

Background: Canine angiostrongylosis is a nematode infection in domestic dogs and wild carnivores. The present report focuses on epidemiological, clinical and histopathological findings in a case of fatal disseminated angiostrongylosis in a dog living in southern Italy and provides data on the extent of the spread of Angiostrongylus vasorum in the same area.Case presentation: A 4-year-old female English Setter from the Campania region of southern Italy was referred with a 2-week history of cough and severe respiratory distress that did not respond to antimicrobial therapy. Based on clinical, radiological, echographical and cytological findings (including the presence of larvae), a suspect diagnosis of lungworm infection was performed. After few days the dog died due to progressive clinical aggravation. Complete postmortem examination was conducted within 24 hours from death and samples from lungs, heart, liver, kidney, spleen, stomach and small intestine were fixed in 10% buffered formalin. Grossly, several hemorrhagic foci were observed mostly in the lungs, liver, kidney. Microscopically, the lungs contained numerous, multifocal to coalescing granulomas composed of epitheliod macrophages, multinucleated giant cells and some neutrophils, frequently associated with parasite eggs and larvae. The lungs contained many firm nodules, many adult nematodes approximately 1.5 to 2 cm in length were observed in cut sections and identified as A. vasorum. A subsequent parasitological survey performed with FLOTAC on stray dogs living in the same area showed the presence of A. vasorum larvae in 17 of 1639 stray dogs examined (1.04%).Conclusion: This survey provides new data on distribution of A. vasorum and underlines that canine angiostrongylosis should be considered as differential diagnosis in dogs