Cosmic signatures in earth's seismic tremor?

Even in absence of earthquakes, each site on earth experiences continuous elastic vibrations which are mostly traced to the non-linear interactions of sea waves. However, the fine structure of the spectrum at mHz frequencies shows hundreds of highly significant narrow bandwidth peaks, with a persistence and a coincidence with solar acoustic eigenmodes which are incompatible with any geophysical origin. The feasibility of a common cosmic origin is evaluated through an estimate of the gravitational wave cross-section of the earth, combined with its elastic response and with the stochastic amplification produced by the interference of the cosmic signal with tremor of oceanic origin. The measured spectral peaks appear compatible with a gravitational monochromatic illumination at strains $h \gtrsim 10^{-20}$. We analize in detail the band around 2.614 mHz, where the binary white dwarf J0651+2844 - which is the second strongest known gravitational stellar source - is expected to emit. Compatible spectral tremor peaks are found for both the earth and the sun, but their amplitude is 3 o.m. larger than independent estimates, so that a gravitational source attribution would call for a variety of unknown non-luminous sources with definite mass-distance ratios

Characterization of new solid state particle detectors and measurement of the central exclusive production of tt \u304 pairs at CMS

The CERN Large Hadron Collider (LHC) allows particle physics to explore unprecedented regimes and make a huge step forward in the understanding of fundamental interactions. The discovery of the Higgs boson by the ATLAS [1] and CMS [2] collaborations provided an excellent test of the standard model (SM) of particle physics. On the other hand, it is long known that the SM can only be an approximation at low energies of a more general theory, yet to be discovered: therefore, in addition to precision measurements within the SM, searches for signatures of new physics (NP) models beyond the SM represent a key goal of the physics programs of the LHC experiments. Searches are performed analysing a range of experimental signatures as wide as possible. So far, no evidence for deviations from the SM has been reported. The top quark, owing to its large mass, close to the electroweak (EWK) symmetry breaking scale, has long been seen as a window on NP. Several NP models indeed foresee a privileged role for the top quark sector. The LHC experiments have a huge program of measurements of top quark properties. At the LHC, in proton-proton collisions, the top quark is predominantly produced via quantum chromodynamics (QCD) diagrams that yield top quark-antiquark pairs, or via EWK diagrams in the so called \u201dsingle top\u201d production. Recently, at the CMS collaboration, the possibility arose to explore a new production mechanism of the top quark, the central exclusive production via gamma-gamma fusion. In fact, beam protons can often interact without disintegrating themselves, rather losing a small fraction of their energy and momentum, by exchanging photons, for example, and continuing their path: the lost 4-momentum can yield a variety of particles, referred to as the X system in the following, giving rise to events of the form pp \u2192 pXp; the X system can be top quark-antiquark pairs. CMS installed a new detector, the proton precision spectrometer (PPS), positioned at around 210m, along the beam line, on either side of the beam inter- action point: PPS allows to reconstruct those protons that interacted without disintegrating themselves. The measurement of the proton lost momentum, together with the reconstruction of the decay products of the X system by the central CMS detector, allows the study of events of the form pp \u2192 pttp. The cross section for this process has never been measured before. From a theoretical point of view, in the context of the standard model, the cross section is foreseen to be very small, generally below 1fb: calculations using the Monte Carlo generator FPMC [3] combined with MadGraph5 [4] yield a value of around 0.3fb. However NP scenarios can enhance it to values that can be tested with the data already collected by the LHC. In my PhD thesis, I participated in the ongoing efforts to measure the cross section of the pp \u2192 pttp process, selecting the so-called semi-leptonic channel, that is events where one of the two top quarks decays to a fully hadronic final state and the other to a final state containing a charged lepton-neutrino pair. While in the first run of its operation PPS comprised silicon-strip tracking detectors, a new silicon-pixel-based detector has been designed and built: during my PhD, I participated in all phases of the construction, commissioning and installation of the new pixel detectors. The system is made of several layers of sensitive material arranged in a mechanical structure, called \u201droman pot\u201d, that allows a positioning very close to the beam line: in fact, protons undergo only a tiny deviation after the interaction and, exploiting the LHC optics system, at 210mathrmm from the interaction point, they are still very close to the beam line. For these reasons, PPS silicon detectors operate under extreme conditions, in a very high radiation environment. Characterising and optimising the behaviour of the new detectors under various levels of radiation exposure played a role of paramount importance during the commissioning phase. The LHC is in operation since 2008. With the aging of some parts and the evolution of the operating conditions, the experiments have constantly updated and improved all systems along the years, taking advantage of the continuous advancements of the technologies for particle detectors. In 2020, the LHC and the experiments were in a shutdown phase for repairs and upgrades. In 2022, the operations will resume with a higher proton center-of-mass energy and with a larger luminosity. Very high luminosities yield extreme pile-up conditions, that is a large number of multiple interactions during the same beam bunch crossing, a phenomenon that can make event reconstruction problematic for the experiments. To cope with such extreme operating conditions, and at the same time maintain excellent performances, efforts have been devoted to design new generation timing detectors: in addition to spatial information, a precise tim- ing information in fact can help correctly assigning the reconstructed tracks to the interaction that produced them. In my PhD, I joined the TimeSpot collaboration, a team aimed at conceiving new solid-state timing detectors that implement novel configurations of p-n junctions to achieve unprecedented reso- lutions on the timing measurements

Predictability of Volcano Eruption: lessons from a basaltic effusive volcano

Volcano eruption forecast remains a challenging and controversial problem despite the fact that data from volcano monitoring significantly increased in quantity and quality during the last decades.This study uses pattern recognition techniques to quantify the predictability of the 15 Piton de la Fournaise (PdlF) eruptions in the 1988-2001 period using increase of the daily seismicity rate as a precursor. Lead time of this prediction is a few days to weeks. Using the daily seismicity rate, we formulate a simple prediction rule, use it for retrospective prediction of the 15 eruptions,and test the prediction quality with error diagrams. The best prediction performance corresponds to averaging the daily seismicity rate over 5 days and issuing a prediction alarm for 5 days. 65% of the eruptions are predicted for an alarm duration less than 20% of the time considered. Even though this result is concomitant of a large number of false alarms, it is obtained with a crude counting of daily events that are available from most volcano observatoriesComment: 4 pages, 4 figure

Temperature dependence of the response of ultra fast silicon detectors

The Ultra Fast Silicon Detectors (UFSD) are a novel concept of silicon detectors based on the Low Gain Avalanche Diode (LGAD) technology, which are able to obtain time resolution of the order of a few tens of picoseconds. First prototypes with different geometries (pads/pixels/strips), thickness (300 and 50μm), and gain (between 5 and 20) have been recently designed and manufactured by CNM (Centro Nacional de Microelectrónica, Barcelona) and FBK (Fondazione Bruno Kessler, Trento). Several measurements on these devices have been performed in the laboratory and in beam test and dependence of the gain on the temperature has been observed. Some of the first measurements will be shown (leakage current, breakdown voltage, gain, and time resolution on the 300μm from FBK and gain on the 50μm-thick sensor from CNM) and a comparison with the theoretically predicted trend will be discussed

The Different Response of Apparently Identical Structures: a Far-Field Lesson from the Mirandola 20th May 2012 Earthquake

Abstract Twin structures, that is structures very similar in terms of geometry, materials, mass distribution etc., founded on the same soil and set at very close distance, are rationally expected to have an identical response to earthquakes. When this does not occur, a role is usually played by factors like the interaction with the surrounding structures or by other anomalies hidden behind the apparent similarity. We present the case of two apparently twin towers that showed a very different response to the 2012 Mirandola (Italy) earthquake ground shaking: one remained perfectly intact while the other had a wide set of fractures on secondary walls. This resulted to be the effect of several contributing factors: the stiffness of the two structures, experimentally measured, provided unexpected differences. This reflected into different modal frequencies for the two towers, with the first and second modes of the damaged tower coincident or very close to the soil resonance. The final result was a coupled soil-structure resonance, implying a much higher displacement of one tower compared to the other, under the same input motion. In Italy, insurance against earthquake damage will probably become compulsory in the near future. This case suggests that the specific soil-structure and structure-structure interaction will have to be carefully evaluated since they can critically affect even apparently identical structures

Why is Probabilistic Seismic Hazard Analysis (PSHA) still used

Abstract Even though it has never been validated by objective testing, Probabilistic Seismic Hazard Analysis (PSHA) has been widely used for almost 50 years by governments and industry in applications with lives and property hanging in the balance, such as deciding safety criteria for nuclear power plants, making official national hazard maps, developing building code requirements, and determining earthquake insurance rates. PSHA rests on assumptions now known to conflict with earthquake physics; many damaging earthquakes, including the 1988 Spitak, Armenia, event and the 2011 Tohoku, Japan, event, have occurred in regions relatively rated low-risk by PSHA hazard maps. No extant method, including PSHA, produces reliable estimates of seismic hazard. Earthquake hazard mitigation should be recognized to be inherently political, involving a tradeoff between uncertain costs and uncertain risks. Earthquake scientists, engineers, and risk managers can make important contributions to the hard problem of allocating limited resources wisely, but government officials and stakeholders must take responsibility for the risks of accidents due to natural events that exceed the adopted safety criteria

Older people and smartwatches, initial experiences

Las tecnologías wearables, como los smartwatches (relojes inteligentes), se han visto como una oportunidad para resolver problemas, a menudo relacionados con las personas mayores (55+), tales como manejo de emergencias, falta de actividad física, y soledad. Sin embargo poco se sabe sobre en qué medida tales personas apropiarían estos dispositivos. Dotamos a 11 personas mayores con relojes inteligentes y seguimos sus primeras experiencia principalmente con dos entrevistas. De acuerdo con los resultados, las experiencias previas con otras tecnologías de la información y la comunicación, y las actitudes positivas hacia la tecnología fueron fundamentales para una primera apropiación de la nueva tecnología, y para superar los primeros problemas. Además el uso estuvo muy relacionado con las expectativas y los hábitos personales. Los participantes usaron los relojes en forma similar a la descrita en estudios previos con adultos (18-64), que incluye el manejo de notificaciones y los sistemas para seguimiento deportivo. El reloj proveía a la mayoría de los participantes un status social (asociado a ser guay, snob o joven), y creaba oportunidades o preocupaciones sobre el estilo personal.Abstract While wearable technologies, such as smartwatches, are seen as an opportunity to solve some problems often related to older people (65+), e.g. emergencies, physical activity, or isolation, little is known about how older people would domesticate such new technologies. In this study we provided eleven older individuals with smartwatches and tracked their expectations and initial experiences using two interviews. According to our preliminary findings, previous experience with ICTs along with optimistic attitudes toward technology were key to initial domestication of the new technology and overcoming initial problems. Moreover, use was closely related to expectations and personal habits. Participants in this study used smartwatches in similar ways to to those described in previous studies with adults (18–64), including managing notifications and sports’ tracking. Additionally, users reported that the smartwatch provided a boost in social status (associated with attributes such as cool, snobbish, young) and created some fashion opportunities and/or concerns

Association of the HLA-A2, Cw2, B27, S31, DR2 haplotype with Ankylosing Spondylitis. A possible role of non-B27 factors in the disease

With the aim of searching for HLA haplotypes and non-B27 allele frequency variations in Sardinian AS patients, HLA-A, B, Cw, DR, DQ and Bf, C4A and C4B typing and haplotype assignment was carried out in the families of 25 AS patients and in 44 healthy individuals, all B27 heterozygotes. In the AS patients a significant increase of the A2, Cw2, B27, DR2, DQ1 haplotype was found. This depends only partially on the linkage disequilibrium existing in the Sardinian population between B27 and the other alleles of this haplotype, and rather seems to be due to a primary association of Cw2 and DR2 alleles with AS. Preliminary data seem to show that this haplotype bears the S3l complotype and the ORB1 * 1601 allele both in the AS patients and in the healthy controls. The pathogenetic implications of these findings are discussed