Bulk gravitons from a cosmological brane

We investigate the emission of gravitons by a cosmological brane into an Anti de Sitter five-dimensional bulk spacetime. We focus on the distribution of gravitons in the bulk and the associated production of `dark radiation' in this process. In order to evaluate precisely the amount of dark radiation in the late low-energy regime, corresponding to standard cosmology, we study numerically the emission, propagation and bouncing off the brane of bulk gravitons.Comment: 27 pages, 5 figures, minor corrections. Final versio

Determination of total silicon and SiO2 particles using an ICP-MS based analytical platform for toxicokinetic studies of synthetic amorphous silica

Synthetic amorphous silica (SAS), manufactured in pyrogenic or precipitated form, is a nanomaterial with a widespread use as food additive (E 551). Oral exposure to SAS results from its use in food and dietary supplements, pharmaceuticals and toothpaste. Recent evidence suggests that oral exposure to SAS may pose health risks and highlights the need to address the toxic potential of SAS as affected by the physicochemical characteristics of the different forms of SAS. For this aim, investigating SAS toxicokinetics is of crucial importance and an analytical strategy for such an undertaking is presented. The minimization of silicon background in tissues, control of contamination (including silicon release from equipment), high-throughput sample treatment, elimination of spectral interferences affecting inductively coupled plasma mass spectrometry (ICP-MS) silicon detection, and development of analytical quality control tools are the cornerstones of this strategy. A validated method combining sample digestion with silicon determination by reaction cell ICP-MS is presented. Silica particles are converted to soluble silicon by microwave dissolution with mixtures of HNO3, H2 O2 and hydrofluoric acid (HF), whereas interference-free ICP-MS detection of total silicon is achieved by ion-molecule chemistry with limits of detection (LoDs) in the range 0.2–0.5 µg Si g−1 for most tissues. Deposition of particulate SiO2 in tissues is assessed by single particle ICP-MS

Cosmology of a brane radiating gravitons into the extra dimension

We study in a self-consistent way the impact of the emission of bulk gravitons on the (homogeneous) cosmology of a three-brane embedded in a five-dimensional spacetime. In the low energy regime, we recover the well known result that the bulk affects the Friedmann equation only via a radiation-like term \C/a^4, called dark or Weyl radiation. By contrast, in the high energy regime, we find that the Weyl parameter \C is no longer constant but instead grows very rapidly as \C\propto a^4. As a consequence, the value of \C today is not a free parameter as usually considered but is a fixed number, which, generically, depends only on the number of relativistic degrees of freedom at the high/low energy transition. Our estimated amount of Weyl radiation satisfies the present nucleosynthesis bounds.Comment: 12 page

Non-linear Analysis of Heart rate Variability Improves Differential Diagnosis Between Parkinson Diseases and Multiple System Atrophy

Aims: Parkinson's disease (PD) and multiple system atrophy (MSA) are neurodegenerative disorders characterized by motor "parkinsonian" symptoms and non-motor symptoms related to autonomic nervous system (ANS) dysfunction. The latter can be quantified with the analysis of Heart Rate Variability (HRVa) and of its complexity. In this study nonlinear (NL) HRV complexity parameters were calculated to assess their predictive accuracy as markers of “disease” useful for early differentiation between PD and MSA in parkinsonian syndromes of uncertain diagnosis. Study Design: Observational study. Place and Duration of Study: Clinical Physiology-Biomagnetism Center, Policlinico A. Gemelli, Rome Italy. Patients enrolled from January 2010 to October 2013. Methodology: 51 patients [25 with “certain” diagnosis of PD, 9 with a “highly probable” diagnosis of MSA and 17 with parkinsonian syndromes of uncertain neurological definition (6 with “undefined parkinsonism” and 11 with “suspected MSA”)] and 40 age-matched healthy control subjects were studied. Short-term NL HRVa was performed during daily activity and during REM/NREM sleep from 24 h ECG recordings. Discriminant analysis (DA) was used to identify which NL HRV parameters (or their combination) were efficient to differentiate between PD and MSA in cases of uncertain diagnosis. Results: Compared with healthy controls, most NL HRV parameters were significantly altered in patients (p<0.05), during both active and passive awakeness and during sleep. Most evident HRV abnormalities were found during active awakeness in MSA. DA of recurrence plot parameters provided the best predictive accuracy (76.5%) for the classification of parkinsonian patients with uncertain diagnosis. Conclusion: NL HRVa is efficient in differentiating MSA from PD and may improve earlier diagnosis in patients with parkinsonian symptoms of uncertain nature, useful to address second level diagnostic steps and to guide more individualized drug treatment

Monitoraggio della quantità di ultravioletto B solare sull’Italia meridionale.

Objective: aim of this study was been the evaluation of daily and monthly changes of solar short ultraviolet (UVB) in a central Mediterranean area (Naples city, 40.8623° North) from 1997-2002. Materials and methods: the measurements were automatically collected and expressed as physical units (mW/cm2) and biological units (Minimal Erythema Dose/hour = MED/h). The irradiance unit may be converted to UV Index (UVI) by the conversion factor: 1 [MED/h] = 2.3 on the UVI scale. These values were processed with a special software Solar Light IDL 2.0 that informed us about current UV dose, accumulated UV dose, current UVI, peak UVI, time until sunburn, expressed in mins. Moreover, we studied these parameters by means of a statistical data analyser software called SPSS version 10.0 to obtain information about average values in this last 5 years of measurements. Results: the results showed that: i) the sporadic peaks of maximal irradiance occurred in June; ii) the maximal value of the monthly mean irradiance was observed in June-July, while the minimal one in December-January; iii) the amount of solar UVB that reaches the ground and therefore our skin during the last 5 years has been unmodified. About 20-30% of total daily UVB is received during the interval of time between 60 mins both before and after midday in summer, with 75% between 9 am and 3 pm. In Naples during the summer, half an hour of midday sun exposure of the unacclimatized skin of Caucasian subjects is normally sufficient to result in a subsequent mild reddening of the skin. We report that in Naples the average UVB sunstroke is equal to about 2 MED/day in winter; 7 MED/day in spring and in autumn, 12 MED/day in summer. According to Diffey algorithm, in Naples annual MED is about 2600, and these values have been confirmed by our measurements (2676 MED in 1998, 2591 MED in 1999, 2724 MED in 2000, 2612 in 2001, 2634 in 2002). Conclusions: our results show that erythema could appear, in individuals with skin type II and III living in a touristic Mediterranean area, after about 30 mins of sun exposure, in July; ii) the sunburn risk is higher just during the months when skin hasn't yet acquired the natural defences to respond to the peak of UVB. This monitoring may give more information about photodermatitis, photocarcinogenesis and some preventative devices of exposure to sun rays

Maximal Temperature in Flux Compactifications

Thermal corrections have an important effect on moduli stabilization leading to the existence of a maximal temperature, beyond which the compact dimensions decompactify. In this note, we discuss generality of our earlier analysis and apply it to the case of flux compactifications. The maximal temperature is again found to be controlled by the supersymmetry breaking scale, T_{crit} \sim \sqrt{m_{3/2} M_P}.Comment: 10 pages, 10 figures. v2:comment and references adde

Baryogenesis vs. proton stability in theories with extra dimensions

We propose a new scenario of baryogenesis in the context of theories with large extra dimensions. The baryon number is almost conserved at zero temperature by means of a localization mechanism recently analyzed by Arkani-Hamed and Schmaltz: leptons and quarks are located at two slightly displaced positions in the extra space, and this naturally suppresses the interactions which ``convert'' the latter in the former. We show that this is expected to be no longer true when finite temperature effects are taken into account. The whole scenario is first presented in its generality, without referring to the bulk geometry or to the specific mechanism which may generate the baryon asymmetry. As an example, we then focus on a baryogenesis model reminiscent of GUT baryogenesis. The Sakharov out of equilibrium condition is satisfied by assuming nonthermal production of the bosons that induce baryon number violation.Comment: 10 pages, 1 figur