Quantum reduced loop gravity effective Hamiltonians from a statistical regularization scheme

We introduce a new regularization scheme for Quantum Cosmology in Loop Quantum Gravity (LQG) using the tools of Quantum Reduced Loop Gravity (QRLG). It is obtained considering density matrices for superposition of graphs based on statistical countings of microstates compatible with macroscopic configurations. We call this procedure statistical regularization scheme. In particular, we show how the $\mu_0$ and $\bar{\mu}$ schemes introduced in Loop Quantum Cosmology (LQC) emerge with specific choices of density matrices. Within this new scheme we compute effective Hamiltonians suitable to describe quantum corrected Friedmann and Bianchi I universes and their leading orders coincide with the corresponding effective LQC Hamiltonians in the $\bar{\mu}$ scheme. We compute the next to the leading orders corrections and numerical investigation of the resulting dynamics shows evidence for the emergent-bouncing universe scenario to be a general property of the isotropic sector of QRLG.Comment: 22 pages, 4 figures. Two small typos fixed. Conclusions unchange

2-vertex Lorentzian Spin Foam Amplitudes for Dipole Transitions

We compute transition amplitudes between two spin networks with dipole graphs, using the Lorentzian EPRL model with up to two (non-simplicial) vertices. We find power-law decreasing amplitudes in the large spin limit, decreasing faster as the complexity of the foam increases. There are no oscillations nor asymptotic Regge actions at the order considered, nonetheless the amplitudes still induce non-trivial correlations. Spin correlations between the two dipoles appear only when one internal face is present in the foam. We compute them within a mini-superspace description, finding positive correlations, decreasing in value with the Immirzi parameter. The paper also provides an explicit guide to computing Lorentzian amplitudes using the factorisation property of SL(2,C) Clebsch-Gordan coefficients in terms of SU(2) ones. We discuss some of the difficulties of non-simplicial foams, and provide a specific criterion to partially limit the proliferation of diagrams. We systematically compare the results with the simplified EPRLs model, much faster to evaluate, to learn evidence on when it provides reliable approximations of the full amplitudes. Finally, we comment on implications of our results for the physics of non-simplicial spin foams and their resummation.Comment: 27 pages + appendix, many figures. v2: one more numerical result, plus minor amendment

Bianchi I effective dynamics in Quantum Reduced Loop Gravity

The effective quantum dynamics of Bianchi I spacetime is addressed within the statistical regularization scheme in Quantum Reduced Loop Gravity. The case of a minimally coupled massless scalar field is studied and compared with the effective $\bar{\mu}-$Loop Quantum Cosmology. The dynamics provided by the two approaches match in the semiclassical limit but differ significantly after the bounces. Analytical and numerical inspections show that energy density, expansion scalar and shear are bounded also in Quantum Reduced Loop Gravity and the classical singularity is resolved for generic initial conditions in all spatial directions.Comment: 19 pages, 23 figures, 1 tabl

Can quasicrystals survive in planetary collisions?

We investigated the compressional behavior of i-AlCuFe quasicrystal using diamond anvil cell under quasi-hydrostatic conditions by in situ angle-dispersive X-ray powder diffraction measurements (in both compression and decompression) up to 76 GPa at ambient temperature using neon as pressure medium. These data were compared with those collected up to 104 GPa using KCl as pressure medium available in literature. In general, both sets of data indicate that individual d-spacing shows a continuous decrease with pressure with no drastic changes associated to structural phase transformations or amorphization. The d/d0, where d0 is the d-spacing at ambient pressure, showed a general isotropic compression behavior. The zero-pressure bulk modulus and its pressure derivative were calculated fitting the volume data to both the Murnaghan- and Birch-Murnaghan equation of state models. Results from this study extend our knowledge on the stability of icosahedrite at very high pressure and reinforce the evidence that natural quasicrystals formed during a shock event in asteroidal collisions and survived for eons in the history of the Solar System. [Figure not available: see fulltext.

Diffuse soil CO2 degassing from Linosa island

Herein, we present and discuss the result of 148 measurements of soil CO2 flux performed for the first time in Linosa island (Sicily Channel, Italy), a Plio-Pleistocene volcanic complex no longer active but still of interest owing to its location within a seismically active portion of the Sicily Channel rift system. The main purpose of this survey was to assess the occurrence of CO2 soil degassing, and compare flux estimations from this island with data of soil degassing from worldwide active volcanic as well as non-volcanic areas. To this aim soil CO2 fluxes were measured over a surface of about 4.2 km2 covering ~80% of the island. The soil CO2 degassing was observed to be mainly concentrated in the eastern part of the island likely due to volcano-tectonic lineaments, the presence of which is in good agreement with the known predominant regional faults system. Then, the collected data were interpreted using sequential Gaussian simulation that allowed estimating the total CO2 emissions of the island. Results show low levels of CO2 emissions from the soil of the island (~55 ton d-1) compared with CO2 emissions of currently active volcanic areas, such as Miyakejima (Japan) and Vulcano (Italy). Results from this study suggest that soil degassing in Linosa is mainly fed by superficial organic activity with a moderate contribution of a deep CO2 likely driven by NWSE trending active tectonic structures in the eastern part of the island

First measurements of the Fe oxidation state of spinel inclusions inolivine single crystals from Vulture (Italy) with the in situ synchrotronmicro-Mossbauer technique

The redox state of the Earth's upper mantle (i.e., oxygen fugacity, f(O2)) is a key variable that influences numerous processes occurring at depth like the mobility of volatile species, partial melting, and metasomatism. It is linked to the oxidation state of peridotite rocks, which is normally determined through the available oxythermobarometers after measuring the chemical composition of equilibrated rock-forming minerals and the Fe3+ in redox-sensitive minerals like spinel or garnet. To date, accurate measurements of Fe3+ / Sigma Fe in peridotites have been limited to those peridotites (e.g., harzburgites and lherzolites) for which an oxythermobarometer exists and where spinel (or garnet) crystals can be easily separated and measured by conventional Fe-57 Mossbauer spectroscopy. Wehrlitic rocks have been generally formed by the interaction of a lherzolite with carbonatitic melts and, therefore, have recorded the passage of (metasomatic) fluids at mantle conditions. However, no oxythermobarometer exists to determine their equilibrium f(O2).The aim of this study was to retrieve the f(O2) of the mantle beneath Mt. Vulture volcano (Italy) through the study of a wehrlitic lapillus emitted during the last eruption (similar to 140 kyr ago) that contain olivines with multiple tiny spinel inclusions with sizes < 40 mu m. To our knowledge, the Fe oxidation state of these inclusions has been never determined with the Mossbauer technique due to their small sizes.Here, we present measurements of the Fe3+ / Sigma Fe using in situ synchrotron Mossbauer spectroscopy coupled with chemical and spectroscopic analysis of both host olivine and spinel inclusions.The results show Fe3+ / Sigma Fe ratios of 0.03-0.05 for olivine and 0.40-0.45 for the included spinels, the latter of which appear higher than those reported in literature for mantle spinel harzburgites and lherzolites. Given the evidence of the mantle origin of the trapped spinels, we propose that the high f(O2) (between 0.81 and 1.00 log above the fayalite-magnetite-quartz buffer; FMQ) likely results from the interaction between the pristine spinel lherzolite and a CO2-rich metasomatic agent prior to the spinel entrapment in olivines at mantle depths

Fast Damping in Beam Envelope Oscillation Amplitudes of mismatched high intensity beams

Abstract Recently, a very fast damping of beam envelope oscillation amplitudes has been observed in simulations of high intensity beams transportation through periodic FODO cells, in mismatched conditions In this presentation, further simulations, which seem confirm that the fast damping is due to the Landau damping effect, will be shown and discussed with more details

The comparative effectiveness of initiating fluticasone/salmeterol combination therapy via pMDI versus DPI in reducing exacerbations and treatment escalation in COPD: a UK database study

Rupert Jones,1 Jessica Martin,2 Vicky Thomas,3 Derek Skinner,4 Jonathan Marshall,5 Martina Stagno d’Alcontres,2 David Price2,6 1Clinical Trials and Health Research, Institute of Translational and Stratified Medicine, Plymouth University Peninsula School of Medicine and Dentistry, Plymouth, UK; 2Observational and Pragmatic Research Institute, Singapore; 3Cambridge Research Support, Cambridge, UK; 4Optimum Patient Care, Cambridge, UK; 5Mundipharma International Limited, Cambridge, UK; 6Centre for Academic Primary Care, University of Aberdeen, Aberdeen, UK Abstract: Chronic obstructive pulmonary disease (COPD), a complex progressive disease, is currently the third leading cause of death worldwide. One recommended treatment option is fixed-dose combination therapy of an inhaled corticosteroid (ICS)/long-acting β-agonist. Clinical trials suggest pressurized metered-dose inhalers (pMDIs) and dry powder inhalers (DPIs) show similar efficacy and safety profiles in COPD. Real-world observational studies have shown that combination therapy has significantly greater odds of achieving asthma control when delivered via pMDIs. Our aim was to compare effectiveness, in terms of moderate/severe COPD exacerbations and long-acting muscarinic antagonist (LAMA) prescriptions, for COPD patients initiating fluticasone propionate (FP)/salmeterol xinafoate (SAL) via pMDI versus DPI at two doses of FP (500 and 1,000 µg/d) using a real-life, historical matched cohort study. COPD patients with ≥2 years continuous practice data, ≥2 prescriptions for FP/SAL via pMDI/DPI, and no prescription for ICS were selected from the Optimum Patient Care Research Database. Patients were matched 1:1. Rate of moderate/severe COPD exacerbations and odds of LAMA prescription were analyzed using conditional Poisson and logistic regression, respectively. Of 472 patients on 500 µg/d, we observed fewer moderate/severe exacerbations in patients using pMDI (99 [42%]) versus DPI (115 [49%]) (adjusted rate ratio: 0.71; 95% confidence interval: 0.54, 0.93), an important result since the pMDI is not licensed for COPD in the UK, USA, or China. At 1,000 µg/d, we observed lower LAMA prescription for pMDI (adjusted odds ratio: 0.71; 95% confidence interval: 0.55, 0.91), but no difference in exacerbation rates, potentially due to higher dose of ICS overcoming low lung delivery from the DPI. Keywords: COPD, inhaler type, exacerbations, pneumonia, diabetes, dose-response, inhaled steroid/LABA combination&nbsp

First measurements of the Fe oxidation state of spinel inclusions in olivine single crystals from Vulture (Italy) with the in situ synchrotron micro-Mössbauer technique

The redox state of the Earth's upper mantle (i.e., oxygen fugacity, fO2) is a key variable that influences numerous processes occurring at depth like the mobility of volatile species, partial melting, and metasomatism. It is linked to the oxidation state of peridotite rocks, which is normally determined through the available oxythermobarometers after measuring the chemical composition of equilibrated rock-forming minerals and the Fe3+ in redox-sensitive minerals like spinel or garnet. To date, accurate measurements of Fe3+ / ∑Fe in peridotites have been limited to those peridotites (e.g., harzburgites and lherzolites) for which an oxythermobarometer exists and where spinel (or garnet) crystals can be easily separated and measured by conventional 57Fe Mössbauer spectroscopy. Wehrlitic rocks have been generally formed by the interaction of a lherzolite with carbonatitic melts and, therefore, have recorded the passage of (metasomatic) fluids at mantle conditions. However, no oxythermobarometer exists to determine their equilibrium fO2. The aim of this study was to retrieve the fO2 of the mantle beneath Mt. Vulture volcano (Italy) through the study of a wehrlitic lapillus emitted during the last eruption (∼ 140 kyr ago) that contain olivines with multiple tiny spinel inclusions with sizes &lt; 40 µm. To our knowledge, the Fe oxidation state of these inclusions has been never determined with the Mössbauer technique due to their small sizes. Here, we present measurements of the Fe3+ / ∑Fe using in situ synchrotron Mössbauer spectroscopy coupled with chemical and spectroscopic analysis of both host olivine and spinel inclusions. The results show Fe3+ / ∑Fe ratios of 0.03–0.05 for olivine and 0.40–0.45 for the included spinels, the latter of which appear higher than those reported in literature for mantle spinel harzburgites and lherzolites. Given the evidence of the mantle origin of the trapped spinels, we propose that the high fO2 (between 0.81 and 1.00 log above the fayalite–magnetite–quartz buffer; FMQ) likely results from the interaction between the pristine spinel lherzolite and a CO2-rich metasomatic agent prior to the spinel entrapment in olivines at mantle depths.</p