Variational approach to gravitational theories with two independent connections

A new variational approach for general relativity and modified theories of gravity is presented. In addition to the metric tensor, two independent affine connections enter the action as dynamical variables. In the matter action the dependence upon one of the connections is left completely unspecified. When the variation is applied to the Einstein-Hilbert action the Einstein field equations are recovered. However when applied to $f(R)$ and Scalar-Tensor theories, it yields gravitational field equations which differ from their equivalents obtained with a metric or Palatini variation and reduce to the former ones only when no connections appear in the matter action.Comment: 11 pages, no figure

Inflationary Perturbations in Palatini Generalised Gravity

We examine the generation of primordial perturbations during an inflationary epoch in generalised theories of gravity when the equations of motion are derived using the Palatini variational principle. Both f(R) and Scalar-Tensor theories are considered and we compare our results with those obtained under the conventional metric formalism. Non-linear generalisations of the action lead to different theories under the two variational choices and we obtain distinct results for scalar and tensor spectral indices and their ratio. We find the following general result; inflation driven solely by f(R) modifications alone do not result in suitable curvature perturbations whilst Scalar-Tensor theories generate nearly scalar invariant curvature perturbations but no tensor modes.Comment: 9 page

Good and bad tetrads in f(T) gravity

We investigate the importance of choosing good tetrads for the study of the field equations of $f(T)$ gravity. It is well known that this theory is not invariant under local Lorentz transformations, and therefore the choice of tetrad plays a crucial role in such models. Different tetrads will lead to different field equations which in turn have different solutions. We suggest to speak of a good tetrad if it imposes no restrictions on the form of $f(T)$. Employing local rotations, we construct good tetrads in the context of homogeneity and isotropy, and spherical symmetry, where we show how to find Schwarzschild-de Sitter solutions in vacuum. Our principal approach should be applicable to other symmetries as well.Comment: 25 page

Extensive carrier testing and CF birth prevalence: evidence for a negative correlation

Aim of the study was to evaluate if extensive CF carrier testing may be connected with the progressive decrease of CF birth incidence recorded in North Eastern Italy. From 1993 to 2007 an average 52,000 newborns per year underwent Neonatal Screening (NS), and 198 newborns with CF were detected (1/3937). A time related contraction in birth prevalence was confirmed, with an average annual percent decrease of 0.15 per 10,000 neonates (Poisson regression analysis p 0.003). In the NS area two sections were identified: the Western Region (WR), where CF carrier testing is not offered to couples from the general population, and the Eastern Region (ER), where CF carrier testing is widely offered to couples from the general population. In ER from 1995 to 2007 such testing practice has been steadily expanding, with a total of 87,721 CF carrier tests performed, 3460 carriers identified, and 238 carrier couples detected (data collection in progress). The prevalence of CF decreased by time (p<0.001) but the rate of decrease was more enhanced in ER as suggested by the existence of a statistically significant (p = 0.014) interaction term between time and region in the Poisson regression model. The overall negative trend in North Eastern Italy is due to a contraction of CF births in its Eastern part. In ER a negative correlation was found between CF incidence and the number of carrier tests (p 0.012). Prenatal diagnosis data collection is in progress. These data support the hypothesis that carrier screening may modify the incidence of CF

Insight into the WNT system and its drug related response.

The WNT signalling pathway is a complex system for transferring information for DNA expression from the cell surface receptors to cytoplasm and then to the nucleus. It is based on several proteins that work together as agonists and antagonists in order to maintain homeostasys and to promote anabolic processes. The WNT system acts on all cellular lines involved in bone resorption and formation. WNT pathway can mainly be triggered by two different signalling cascades. The first is well known and is the so-called WNT-beta catenin system (or the canonical pathway), the second is known as the non canonical WNT pathway. WNT proteins form a superfamily of secreted glycoproteins. The association with surface receptors, called Frizzled, that are members of the G protein-coupled receptors superfamily and co receptors like low-density lipoprotein receptor-related proteins 5 and 6 (LRP5/6) complete the WNT system. LRP5/6 show high affinity for WNT antagonists that modulate the activity of this pathway: DKK1 and sclerostin (SCL), that play a crucial role in modulating the WNT system. The WNT-pathway and in particular its antagonists SCL and DKK1 seems to play a key role in the regulation of bone remodeling during treatment with bone active agents such as bisphosphonates, but not only. Their effects become relevant especially in the course of long-term treatments

Massive black hole binaries in LISA: multimessenger prospects and electromagnetic counterparts

In the next decade, the Laser Interferometer Space Antenna (LISA) will detect the coalescence of massive black hole binaries (MBHBs) in the range $[10^4, 10^8] \, \rm M_{\odot}$, up to $z\sim10$. Their gravitational wave (GW) signal is expected to be accompanied by an electromagnetic counterpart (EMcp), generated by the gas accreting on the binary or on the remnant BH. In this work, we present the number and characteristics (such as redshift and mass distribution, apparent magnitudes or fluxes) of EMcps detectable jointly by LISA and some representative EM telescopes. We combine state-of-the-art astrophysical models for the galaxies formation and evolution to build the MBHBs catalogues, with Bayesian tools to estimate the binary sky position uncertainty from the GW signal. Exploiting additional information from the astrophysical models, such as the amount of accreted gas and the BH spins, we evaluate the expected EM emission in the soft X-ray, optical and radio bands. Overall, we predict between 7 and 21 EMcps in 4 yrs of joint observations by LISA and the considered EM facilities, depending on the astrophysical model. We also explore the impact of the hydrogen and dust obscuration of the optical and X-ray emissions, as well as of the collimation of the radio emission: these effects reduce the number to EMcps to 2 or 3, depending on the astrophysical model, again in 4 yrs of observations. Most of the EMcps are characterised by faint EM emission, challenging the observational capabilities of future telescopes. Finally, we also find that systems with multi-modal sky position posterior distributions represent only a minority of cases and do not affect significantly the number of EMcps.Comment: 28 pages, 18 figures. Submitted to PR

Análise da prevalência e fatores associados à incontinência urinária entre idosos do Município de São Paulo, Brasil: Estudo SABE (Saúde, Bem-Estar e Envelhecimento)

To investigate the prevalence of urinary incontinence among elderly people living in São Paulo, Brazil and their associated risk factors. The Pan-American Health Organization and World Health Organization coordinated a multicenter study named Health, Wellbeing and Aging (SABE Study) in elderly people (over 60 years old) living in seven countries in Latin America and the Caribbean. In Brazil, the study was carried out in São Paulo in the year 2000. The total Brazilian sample included 2,143 people. The prevalence of self reported urinary incontinence was 11.8% among men and 26.2% for women. It was verified that among those reporting urinary incontinence, 37% also reported stroke and 34% depression. It was found that the greater the dependence that the elderly people presented, the greater the prevalence of urinary incontinence. The associated factors found were depression (odds ratio = 2.49), female (2.42), advanced age (2.35), important functional limitation (2.01). Urinary incontinence is a highly prevalent symptom among the elderly population of the municipality of São Paulo, especially among women. The adoption of preventive measures can reduce the negative effects of urinary incontinence.Investigar a prevalência de incontinência urinária entre idosos de São Paulo, Brasil, e fatores associados e de risco. A Organização Pan-Americana da Saúde e a Organização Mundial da Saúde coordenaram estudo multicêntrico denominado Saúde, Bem-Estar e Envelhecimento (Estudo SABE) em pessoas idosas (60 anos ou mais) que vivem em sete países da América Latina e Caribe. No Brasil, o estudo populacional foi realizado no Município de São Paulo no ano 2000. A amostra total brasileira foi de 2.143 pessoas. A prevalência da incontinência urinária auto-referida foi de 11,8% entre homens e 26,2% entre mulheres. Verificou-se que entre aqueles que relataram incontinência urinária, 37% também relataram acidente vascular cerebral e 34%, depressão. Observou-se que quanto maior a dependência do idoso, maior era a prevalência de incontinência urinária. Os fatores associados encontrados foram depressão (OR = 2,49), sexo feminino (2,42), idade avançada (2,35), limitação funcional (2,01). Incontinência urinária é um sintoma altamente prevalente entre a população idosa do Município de São Paulo, especialmente entre as mulheres. A adoção de medidas preventivas pode reduzir os efeitos negativos da incontinência urinária

Observing GW190521-like binary black holes and their environment with LISA

Binaries of relatively massive black holes like GW190521 have been proposed to form in dense gas environments, such as the disks of Active Galactic Nuclei (AGNs), and they might be associated with transient electromagnetic counterparts. The interactions of this putative environment with the binary could leave a significant imprint at the low gravitational wave frequencies observable with the Laser Interferometer Space Antenna (LISA). We show that LISA will be able to detect up to ten GW190521-like black hole binaries, with sky position errors $\lesssim1$ deg$^2$. Moreover, it will measure directly various effects due to the orbital motion around the supermassive black hole at the center of the AGN, especially the Doppler modulation and the Shapiro time delay. Thanks to a careful treatment of their frequency domain signal, we were able to perform the full parameter estimation of Doppler and Shapiro-modulated binaries as seen by LISA. We find that the Doppler and Shapiro effects will allow for measuring the AGN parameters (radius and inclination of the orbit around the AGN, central black hole mass) with up to percent-level precision. Properly modeling these low-frequency environmental effects is crucial to determine the binary formation history, as well as to avoid biases in the reconstruction of the source parameters and in tests of general relativity with gravitational waves. <br

Constraining the evolution of Newton's constant with slow inspirals observed from spaceborne gravitational-wave detectors

Spaceborne gravitational-wave (GW) detectors observing at milli-Hz and deci-Hz frequencies are expected to detect large numbers of quasi-monochromatic signals. The first and second time-derivative of the GW frequency ($\dot f_0$ and $\ddot f_0$) can be measured for the most favourable sources and used to look for negative post-Newtonian corrections, which can be induced by the source's environment or modifications of general relativity. We present an analytical, Fisher-matrix-based approach to estimate how precisely such corrections can be constrained. We use this method to estimate the bounds attainable on the time evolution of the gravitational constant $G(t)$ with different classes of quasi-monochromatic sources observable with LISA and DECIGO, two representative spaceborne detectors for milli-Hz and deci-Hz GW frequencies. We find that the most constraining source among a simulated population of LISA galactic binaries could yield $\dot G/G_0 \lesssim 10^{-6}\text{yr}^{-1}$, while the best currently known verification binary will reach $\dot G/G_0 \lesssim 10^{-4}\text{yr}^{-1}$. We also perform Monte-Carlo simulations using quasi-monochromatic waveforms to check the validity of our Fisher-matrix approach, as well as inspiralling waveforms to analyse binaries that do not satisfy the quasi-monochromatic assumption. We find that our analytical Fisher matrix produces good order-of-magnitude constraints even for sources well beyond its regime of validity. Monte-Carlo investigations also show that chirping stellar-mass compact binaries detected by DECIGO-like detectors at cosmological distances of tens of Mpc can yield constraints as tight as $\dot G/G_0 \lesssim 10^{-11}\text{yr}^{-1}$.Comment: 10 pages, 3 figure

Phase resetting of the mammalian circadian clock by DNA damage

SummaryTo anticipate the momentum of the day, most organisms have developed an internal clock that drives circadian rhythms in metabolism, physiology, and behavior [1]. Recent studies indicate that cell-cycle progression and DNA-damage-response pathways are under circadian control [2–4]. Because circadian output processes can feed back into the clock, we investigated whether DNA damage affects the mammalian circadian clock. By using Rat-1 fibroblasts expressing an mPer2 promoter-driven luciferase reporter, we show that ionizing radiation exclusively phase advances circadian rhythms in a dose- and time-dependent manner. Notably, this in vitro finding translates to the living animal, because ionizing radiation also phase advanced behavioral rhythms in mice. The underlying mechanism involves ATM-mediated damage signaling as radiation-induced phase shifting was suppressed in fibroblasts from cancer-predisposed ataxia telangiectasia and Nijmegen breakage syndrome patients. Ionizing radiation-induced phase shifting depends on neither upregulation or downregulation of clock gene expression nor on de novo protein synthesis and, thus, differs mechanistically from dexamethasone- and forskolin-provoked clock resetting [5]. Interestingly, ultraviolet light and tert-butyl hydroperoxide also elicited a phase-advancing effect. Taken together, our data provide evidence that the mammalian circadian clock, like that of the lower eukaryote Neurospora [6], responds to DNA damage and suggest that clock resetting is a universal property of DNA damage