Transient Astrophysical Pulses and Quantum Gravity

Searches for transient astrophysical pulses could open an exciting new window into the fundamental physics of quantum gravity. In particular, an evaporating primordial black hole in the presence of an extra dimension can produce a detectable transient pulse. Observations of such a phenomenon can in principle explore the electroweak energy scale, indicating that astrophysical probes of quantum gravity can successfully complement the exciting new physics expected to be discovered in the near future at the Large Hadron Collider.Comment: 7 pages, This essay received an honorable mention in the Gravity Research Foundation Essay Competition, 200

Highly conductive, ionic liquid-based polymer electrolytes

In this manuscript is reported a thermal and impedance spectroscopy investigation carried out on quaternary polymer electrolytes, to be addressed as separators for lithium solid polymer batteries, containing large amount of the N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide ionic liquid. The target is the development of Li+ conducting membranes with enhanced ion transport even below room temperature. Polyethylene oxide and polymethyl methacrylate were selected as the polymeric hosts. A fully dry, solvent-free procedure was followed for the preparation of the polymer electrolytes, which were seen to be self-consistent and handled even upon prolonged storage periods (more than 1 year). Appealing ionic conductivities were observed especially for the PEO electrolytes, i.e., 1.6 × 10-3and 1.5 × 10-4 S cm-1 were reached at 20 and -20°C, respectively, which are ones the best, if not the best ion conduction, never detected for polymer electrolytes

Time and time-frequency analysis of near-infrared signals for the assessment of ozone autohemotherapy long-term effects in multiple sclerosis

Ozone autohemotherapy is an emerging therapeutic technique that is gaining increasing importance in treating neurological disorders. A validated and standard methodology to assess the effect of such therapy on brain metabolism and circulation is however still lacking. We used a near-infrared spectroscopy system (NIRS) to monitor the cerebral oxygenation of 9 subjects: 4 remitting-relapsing multiple sclerosis (MS) sufferers and 5 controls. Subjects were tested before, during, and after ozone autohemotherapy. We monitored the concentration changes in the level of oxygenated and deoxygenated haemoglobin, and in the level of the Cytochrome-c-oxidase (CYT-c). From the time and time-frequency analysis of the NIRS signals we extracted 128 variables, which were used to characterize the metabolic brain pattern during the therapy. We showed that by using only 7 NIRS variables out of 128 it is possible to characterize the metabolic brain pattern of the two groups of subjects. The MS subjects showed a marked increase of the CYT-c activity and concentration about 40 minutes after the end of the autohemotherapy, possibly revealing a reduction of the chronic oxidative stress level typical of MS sufferers. From a technical point of view, this preliminary study showed that NIRS could be useful to show the effects of ozone autohemotherapy at cerebral level, in a long term monitoring. The clinical result of this study is the quantitative measurement of the CYT-c level changes in MS induced by ozone autohemotherap

CFD optimization of large water storages for efficient cooling of high power intermittent thermal loads

The design optimization of water basins for the refrigeration of intermittent high-power heat sources, by mean of CFD simulations, is presented. A case study of an experimental facility is considered, that foreseen two large water basins as thermal storage, with volume of 315 m3 and 500 m3 respectively, and an installed nominal cooling power around 25 MW for the cooling of an intermittent load, with peak power of around 65 MW. A strong horizontal stratification has been looked after in the preliminary design, which include a labyrinth of walls and weirs, and water inlet/outlet plugs positioned at the opposite side of the basins. The intensity and the role of this stratification have been explored using a CFD software, simulating both winter and summer sceneries. Some variants to the original design have been studied, in order to optimize the stratification of water temperatures. It is shown that a large water storage with an optimal design could help very much in reducing cooling power demand in case of intermittent thermal load. Keywords: Large water storage, Thermal stratification, CF

Online Learning with Ensembles

Supervised online learning with an ensemble of students randomized by the choice of initial conditions is analyzed. For the case of the perceptron learning rule, asymptotically the same improvement in the generalization error of the ensemble compared to the performance of a single student is found as in Gibbs learning. For more optimized learning rules, however, using an ensemble yields no improvement. This is explained by showing that for any learning rule $f$ a transform $\tilde{f}$ exists, such that a single student using $\tilde{f}$ has the same generalization behaviour as an ensemble of $f$-students.Comment: 8 pages, 1 figure. Submitted to J.Phys.

Primary energy consumption of heat pumps in high renewable share electricity mixes

The increase of power plants’ conversion efficiencies, together with the high share of renewable energy sources in the electricity production for some countries, pushes for the use of heat pumps for space heating when aiming at reducing the associated primary energy consumption. However, the effective reduction of primary energy consumption should be supported by careful evaluations, as a number of parameters influence the heat pumps performance, including outdoor temperature, supply temperature, heat load and electricity primary energy factor. The variability of such parameters increases the complexity of the analysis, and annual or monthly average calculations might lead to incomplete evaluations and thus to sub-optimal solutions. This paper performs a hourly simulation of the operation of an air-source heat pump for space heating, relying on the available heat demand data of real buildings currently connected to a district heating network. In addition, the paper proposes the calculation of the hourly primary energy factor of the electricity supplied by the power grid, as the variability of the generation sources plays a key role in the global analysis of the energy system’s conversion efficiency. The results show that in all the considered cases the heat pumps provide potential primary energy savings compared to natural gas boilers, thanks to the combined effect of their high coefficient of performance and the low electricity primary energy factor in the analyzed context. The primary energy consumption reduction obtained in each case is in the range 10–40%, with a median value close to 30%. Moreover, the comparison between average and high-resolution calculations of primary energy factors shows the possible underestimation of the potential primary energy savings when yearly or monthly data are adopted

Oxidative potential associated with urban aerosol deposited into the respiratory system and relevant elemental and ionic fraction contributions

Size-segregated aerosol measurements were carried out at an urban and at an industrial site. Soluble and insoluble fractions of elements and inorganic ions were determined. Oxidative potential (OP) was assessed on the soluble fraction of Particulate Matter (PM) by ascorbic acid (AA), dichlorofluorescein (DCFH) and dithiothreitol (DTT) assays. Size resolved elemental, ion and OP doses in the head (H), tracheobronchial (TB) and alveolar (Al) regions were estimated using the Multiple-Path Particle Dosimetry (MPPD) model. The total aerosol respiratory doses due to brake and soil resuspension emissions were higher at the urban than at the industrial site. On the contrary, the doses of anthropic combustion tracers were generally higher at the industrial site. In general, the insoluble fraction was more abundantly distributed in the coarse than in the fine mode and vice versa for the soluble fraction. Consequently, for the latter, the percent of the total respiratory dose deposited in TB and Al regions increased. Oxidative potential assay (OPAA) doses were distributed in the coarse region; therefore, their major contribution was in the H region. The contribution in the TB and Al regions increased for OPDTT and OPDCFH

Development and field evaluation of an online monitor for near-continuous measurement of iron, manganese, and chromium in coarse airborne particulate matter (PM)

A novel air sampling monitor was developed for near-continuous (i.e., 2-h time resolution) measurement of iron (Fe), manganese (Mn), and chromium (Cr) concentrations in ambient coarse particulate matter (PM) (i.e., PM10–2.5). The developed monitor consists of two modules: (1) the coarse PM collection module, utilizing two virtual impactors (VIs) connected to a modified BioSampler to collect ambient coarse PM into aqueous slurry samples; (2) the metal concentration measurement module, which quantifies the light absorption of colored complexes formed through the reactions between the soluble and solubilized target metals and pertinent analytical reagents in the collected slurries using a micro volume flow cell (MVFC) coupled with UV/VIS spectrophotometry. The developed monitor was deployed in the field for continuous ambient PM collection and measurements from January to April 2016 to evaluate its performance and reliability. Overall, the developed monitor could achieve accurate and reliable measurements of the trace metals Fe, Mn, and Cr over long sampling periods, based on the agreement between the metal concentrations measured via this online monitor and off-line parallel measurements obtained using filter samplers. Based on our results, it can be concluded that the developed monitor is a promising technology for near-continuous measurements of metal concentrations in ambient coarse PM. Moreover, this monitor can be readily configured to measure the speciation (i.e., water-soluble portion as well as specific oxidation states) of these metal species. These unique abilities are essential tools in investigations of sources and atmospheric processes influencing the concentrations of these redox-active metals in coarse PM. Copyright © 2016 American Association for Aerosol Research © 2016 American Association for Aerosol Research

CFD optimization of large water storages for efficient cooling of high power intermittent thermal loads

The design optimization of water basins for the refrigeration of intermittent high-power heat sources, by mean of CFD simulations, is presented. A case study of an experimental facility is considered, that foreseen two large water basins as thermal storage, with volume of 315m3 and 500m3 respectively, and an installed nominal cooling power around 25MW for the cooling of an intermittent load, with peak power of around 65MW. A strong horizontal stratification has been looked after in the preliminary design, which include a labyrinth of walls and weirs, and water inlet/outlet plugs positioned at the opposite side of the basins. The intensity and the role of this stratification have been explored using a CFD software, simulating both winter and summer sceneries. Some variants to the original design have been studied, in order to optimize the stratification of water temperatures. Itis shown that a large water storage with an optimal design could help very much in reducing cooling power demand in case of intermittent thermal load