Empirical mode decomposition of long-term polar motion observation

We use the Empirical Mode Decomposition (EMD) method to study the decadal variations in polar motion and its long-term trend since year 1900. The existence of the so-called “Markowitz wobble”, a multidecadal fluctuation of the mean pole of rotation whose nature has long been debated since its discovery in 1960, is confirmed. In the EMD approach, the Markowitz wobble naturally arises as an empirical oscillatory term in polar motion, showing significant amplitude variations and a period of approximately 3 decades. The path of the time-averaged, non-cyclic component of polar motion matches the results of previous investigations based on classical spectral methods. However, our analysis also reveals previously unnoticed steep variations (change points) in the rate and the direction of secular polar motion

Anomalous secular sea-level acceleration in the Baltic Sea caused by isostatic adjustment

Observations from the global array of tide gauges show that global sealevel has been rising at an average rate of 1.5-2 mm/yr during the last ~150 years [Douglas 1991, Spada and Galassi 2012]. Although a global sea-level acceleration was initially ruled out [Douglas 1992], subsequent studies [Douglas 1997, Church and White 2006, Jevrejeva et al. 2008, Church and White 2011] have coherently proposed values of ~1 mm/year/century [Olivieri and Spada 2013]. More complex non-linear trends and abrupt sea-level variations have now also been recognized. Globally, these could manifest a regime shift between the late Holocene and the current rhythms of sea-level rise [Gehrels and Woodworth 2013], while locally they result from ocean circulation anomalies, steric effects and wind stress [Bromirski et al. 2011, Merrifield 2011]. Although isostatic readjustment affects the local rates of secular sea-level change [Milne and Mitrovica 1998, Peltier 2004], a possible impact on regional acceleration has been so far discounted [Douglas 1992, Jevrejeva et al. 2008, Woodworth et al. 2009] since the process evolves on a millennium time scale [Turcotte and Schubert 2002]. Here we report a previously unnoticed anomaly in the long-term sea-level acceleration of the Baltic Sea tide gauge records, and we explain it by the classical post-glacial rebound theory and numerical modeling of glacial isostasy. Contrary to previous assumptions, our findings demonstrate that isostatic compensation plays a role in the regional secular sea-level acceleration

Quantum dynamics of a high-finesse optical cavity coupled with a thin semi-transparent membrane

We study the quantum dynamics of the cavity optomechanical system formed by a Fabry-Perot cavity with a thin vibrating membrane at its center. We first derive the general multimode Hamiltonian describing the radiation pressure interaction between the cavity modes and the vibrational modes of the membrane. We then restrict the analysis to the standard case of a single cavity mode interacting with a single mechanical resonator and we determine to what extent optical absorption by the membrane hinder reaching a quantum regime for the cavity-membrane system. We show that membrane absorption does not pose serious limitations and that one can simultaneously achieve ground state cooling of a vibrational mode of the membrane and stationary optomechanical entanglement with state-of-the-art apparatuses.Comment: 14 pages, 7 figure

Quantum dynamics of a vibrational mode of a membrane within an optical cavity

Optomechanical systems are a promising candidate for the implementation of quantum interfaces for storing and redistributing quantum information. Here we focus on the case of a high-finesse optical cavity with a thin vibrating semitransparent membrane in the middle. We show that robust and stationary optomechanical entanglement could be achieved in the system, even in the presence of nonnegligible optical absorption in the membrane. We also present some preliminary experimental data showing radiation-pressure induced optical bistability.Comment: 6 pages, 2 figures. Work presented at the conference QCMC 2010 held on 19-23 July 2010 at the University of Queensland, Brisbane, Australi

GRBs and the thermalization process of electron-positron plasmas

We discuss the temporal evolution of the pair plasma created in Gamma-Ray Burst sources. A particular attention is paid to the relaxation of the plasma into thermal equilibrium. We also discuss the connection between the dynamics of expansion and the spatial geometry of the plasma. The role of the baryonic loading parameter is emphasized.Comment: 4 pages, 3 figures, in the Proceedings of the "Gamma Ray Bursts 2007" meeting, November 5-9, 2007, Santa Fe, New Mexico, US

The antiquity of hydrocephalus: the first full palaeo-neuropathological description

The Pathology Museum of the University of Florence houses a rich collection of anatomical specimens and over a hundred waxworks portraying pathological conditions occurring in the nineteenth century, when the museum was established. Clinical and autopsy findings of these cases can still be retrieved from the original museum catalogue, offering a rare opportunity for retrospective palaeo-pathological diagnostics. We present a historical case of severe hydrocephalus backed by modern-day anthropological, radiological and molecular analyses conducted on the skeleton of an 18-month-old male infant deceased in 1831. Luigi Calamai (1796-1851), a wax craftsman of La Specola workshop in Florence, was commissioned to create a life-sized wax model of the child's head, neck and upper thorax. This artwork allows us to appreciate the cranial and facial alterations determined by 30 lb of cerebrospinal fluid (CSF) accumulated within the cerebral ventricular system. Based on the autopsy report, gross malformations of the neural tube, tumours and haemorrhage could be excluded. A molecular approach proved helpful in confirming sex. We present this case as the so-far most compelling case of hydrocephalus in palaeo-pathological research

Effect of beet pulp on growing performance, digestibility, N balance, and ammonia emission in the heavy pig

A relevant aspect of pig farm units concerning the environmental impact is the ammonia emission from slurries, which is detrimental for animal (and sometimes also for human) welfare. This emission is co-responsible for acid rains, for the increase of bad smells and is detrimental for the respiratory apparatus (Portejoie et al., 2002)

Dispersion analysis of the nucleon form factors including meson continua

Dispersion relations provide a powerful tool to analyse the electromagnetic form factors of the nucleon for all momentum transfers. Constraints from meson-nucleon scattering data, unitarity, and perturbative QCD can be included in a straightforward way. In particular, we include the 2pi, rho-pi, and KKbar continua as independent input in our analysis and provide an error band for our results. Moreover, we discuss two different methods to include the asymptotic constraints from perturbative QCD. We simultaneously analyze the world data for all four form factors in both the space-like and time-like regions and generally find good agreement with the data. We also extract the nucleon radii and the omega-NN coupling constants. For the radii, we generally find good agreement with other determinations with the exception of the electric charge radius of the proton which comes out smaller. The omega-NN vector coupling constant is determined relatively well by the fits, but for the tensor coupling constant even the sign can not be determined.Comment: 24 pages, 9 figure

Growth and slaughter performance, nitrogen balance and ammonia emission from slurry in pigs fed high fibre diets

The aim of the work was to determine digestibility, nitrogen balance and ammonia emission from excreta, in the typical Italian heavy pig during the last phase of growth, when fed diets with a high fibre content. In comparison with a traditional control diet (C), two diets with 12 and 24% wheat bran (WB12 and WB24) and two other diets with 12 and 24% dried beet pulp (BP12 and BP24) were tested. Totally 76 Landrace x Large White fattening barrows, from 45 to 170 kg live weight distributed in 16 pens, were utilized in the trial. Thirty pigs were allocated to 6 metabolic cages in 5 consecutive periods in order to have 6 observations per treatment. For diets C, WB12 and WB24 daily weight gain (DWG), feed conversion ratio (FCR) and slaughtering performances were also registered, on 20 pigs per dietary treatment. Growing and slaughter performances were similar for pigs fed C and WB12 diets, whilst diet WB24 determined a significant (P<0.05) decrease in performances (growth and feed conversion) in the first period of fattening and a lower dressing percentage at slaughter (85.5, 84.4 and 82.5% for C, WB12 and WB24, respectively). Comparing the diets with the same level of inclusion of the fibrous feeds, WB diets had a lower OM and energy digestibility, while BP diets registered a lower protein but a higher fibre digestibility. Consistently with other experiments, BP diets determined an increase of faecal and a reduction of urinary N, as a percentage of the intake N, as well as a decrease of ammonia emission from the slurries (- 16.6 and -25.3% for BP12 and BP24, in comparison with C diet). For the WB diets the reduction of urinary N and the increase in faecal N were less marked and a reduction of ammonia emissions was not registered

Switchable Genetic Oscillator Operating in Quasi-Stable Mode

Ring topologies of repressing genes have qualitatively different long-term dynamics if the number of genes is odd (they oscillate) or even (they exhibit bistability). However, these attractors may not fully explain the observed behavior in transient and stochastic environments such as the cell. We show here that even repressilators possess quasi-stable, travelling-wave periodic solutions that are reachable, long-lived and robust to parameter changes. These solutions underlie the sustained oscillations observed in even rings in the stochastic regime, even if these circuits are expected to behave as switches. The existence of such solutions can also be exploited for control purposes: operation of the system around the quasi-stable orbit allows us to turn on and off the oscillations reliably and on demand. We illustrate these ideas with a simple protocol based on optical interference that can induce oscillations robustly both in the stochastic and deterministic regimes.Comment: 24 pages, 5 main figure