MeV-scale seesaw and leptogenesis

We study the type-I seesaw model with three right-handed neutrinos and Majorana masses below the pion mass. In this mass range, the model parameter space is not only strongly constrained by the requirement to explain the light neutrino masses, but also by experimental searches and cosmological considerations. In the existing literature, three disjoint regions of potentially viable parameter space have been identified. In one of them, all heavy neutrinos decay shortly before big bang nucleosynthesis. In the other two regions, one of the heavy neutrinos either decays between BBN and the CMB decoupling or is quasi-stable. We show that previously unaccounted constraints from photodisintegration of nuclei practically rule out all relevant decays that happen between BBN and the CMB decoupling. Quite remarkably, if all heavy neutrinos decay before BBN, the baryon asymmetry of the universe can be quite generically explained by low-scale leptogenesis, i.e. without further tuning in addition to what is needed to avoid experimental and cosmological constraints. This motivates searches for heavy neutrinos in pion decay experiments

OUTCOME OF A PILOT COURSE IN SCIENCE COMMUNICATION HIGHLIGHTS THE RELEVANCE OF STUDENT MOTIVATION

The authors devised a lecture series about the common principles making the core of Science Communication, irrespective of specialist disciplines. The aim of the initiative was to engage STEM students, curious about communication of science, into a mostly practical activity, evaluating their degree of satisfaction and the sustainability of the course schedule during the running semester. The course content was originally designed and advertised as an interactive living learning experience. It was then adapted last minute to remote teaching because of the Covid-19 semester, with a significant impact on both the actual interactions and the students’ satisfaction, with respect to expectations. Nonetheless, a follow-up analysis shows that 90% of students declared to have realized, in full or in part, their expected achievements. A high degree of global satisfaction (3.7/5) was acknowledged, despite 77% of students declared a Perceived Study Effort greater than expected. Final grades correlate positively with students Motivation, whereas they are not correlated with any specific Degree Course

New long-lived particle searches in heavy-ion collisions at the LHC

We show that heavy-ion collisions at the LHC provide a promising environment to search for signatures with displaced vertices in well-motivated new physics scenarios. Compared to proton collisions, they offer several advantages: (i) the number of parton level interactions per collision is larger, (ii) there is no pileup, (iii) the lower instantaneous luminosity compared to proton collisions allows one to operate the LHC experiments with very loose triggers, and (iv) there are new production mechanisms that are absent in proton collisions We focus on the third point and show that the modification of the triggers alone can increase the number of observable events by orders of magnitude if the long-lived particles are predominantly produced with low transverse momentum. Our results show that collisions of ions lighter than lead are well motivated from the viewpoint of searches for new physics. We illustrate this for the example of heavy neutrinos in the Neutrino Minimal Standard Model

Repurposing the KCa3.1 inhibitor senicapoc for Alzheimer's disease.

ObjectiveMicroglia play a pivotal role in the initiation and progression of Alzheimer's disease (AD). We here tested the therapeutic hypothesis that the Ca2+-activated potassium channel KCa3.1 constitutes a potential target for treating AD by reducing neuroinflammation.MethodsTo determine if KCa3.1 is relevant to AD, we tested if treating cultured microglia or hippocampal slices with Aβ oligomer (AβO) activated KCa3.1 in microglia, and if microglial KCa3.1 was upregulated in 5xFAD mice and in human AD brains. The expression/activity of KCa3.1 was examined by qPCR, Western blotting, immunohistochemistry, and whole-cell patch-clamp. To investigate the role of KCa3.1 in AD pathology, we resynthesized senicapoc, a clinically tested KCa3.1 blocker, and determined its pharmacokinetic properties and its effect on microglial activation, Aβ deposition and hippocampal long-term potentiation (hLTP) in 5xFAD mice.ResultsWe found markedly enhanced microglial KCa3.1 expression/activity in brains of both 5xFAD mice and AD patients. In hippocampal slices, microglial KCa3.1 expression/activity was increased by AβO treatment, and its inhibition diminished the proinflammatory and hLTP-impairing activities of AβO. Senicapoc exhibited excellent brain penetrance and oral availability, and in 5xFAD mice, reduced neuroinflammation, decreased cerebral amyloid load, and enhanced hippocampal neuronal plasticity.InterpretationOur results prompt us to propose repurposing senicapoc for AD clinical trials, as senicapoc has excellent pharmacological properties and was safe and well-tolerated in a prior phase-3 clinical trial for sickle cell anemia. Such repurposing has the potential to expedite the urgently needed new drug discovery for AD

Crustal structure and Moho depth profile crossing the central Apennines (Italy) along the N42 degree parallel.

We present results from a teleseismic receiver-function study of the crustal structure in the central Apennines (Italy). Data from fifteen stations deployed in a linear transect running along the N42 degree parallel were used for the analysis. A total number of 364 receiver functions were analyzed. The crustal structure has been investigated using the neighborhood algorithm inversion scheme proposed by Sambridge [1999a], obtaining crustal thicknesses, bulk crustal VP/VS ratio and velocity-depth models. In each inversion, the degree of constraint of the different parameters has been appraised by the Bayesian inference algorithm by Sambridge [1999b]. The study region is characterized by crustal complexities and intense tectonic activity (recent volcanism, orogenesis, active extensional processes), and these complexities are reflected in the receiver functions. However, the relatively close spacing among the seismometers (about 20 km) helped us in the reconstruction of the crustal structure and Moho geometry along the transect. Crossing the Apennines from west to east, the Moho depth varies by more than 20 km, going from a relatively shallow depth (around 20 km) on the Tyrrhenian side, deepening down to about 45 km depth beneath the external front of the Apenninic orogen, and rising up again to about 30 km depth in correspondence of the Adriatic foreland. Despite the strong variability of the crustal thickness, the average crustal VS values show little variation along the transect, fluctuating around 3 km/s. The average VP values obtained from the VS and VP /VS are generally lower than 6 km/s

Loop level constraints on Seesaw neutrino mixing

Journal of High Energy Physics 2015.10 (2015): 130 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)We perform a detailed study of the importance of loop corrections when deriving bounds on heavy-active neutrino mixing in the context of general Seesaw mechanisms with extra heavy right-handed neutrinos. We find that, for low-scale Seesaws with an approximate B − L symmetry characterized by electroweak scale Majorana masses and large Yukawas, loop corrections could indeed become relevant in a small part of the parameter space. Previous results in the literature showed that a partial cancellation between these important loop corrections and the tree level contributions could relax some constraints and lead to qualitatively different results upon their inclusion. However, we find that this cancellation can only take place in presence of large violations of the B −L symmetry, that lead to acceptably large contributions to the light neutrino masses at loop level. Thus, when we restrict our analysis of the key observables to an approximate B − L symmetry so as to recover the correct values for neutrino masses, we always find loop corrections to be negligible in the regions of the parameter space preferred by dataWe are happy to acknowledge very illuminating discussions with Mattias Blennow, Belen Gavela, Stefano Rigolin and Alfredo Urbano. We also acknowledge financial support by the European Union through the ITN INVISIBLES (PITN-GA-2011-289442). EFM and JHG also acknowledge support from the EU through the FP7 Marie Curie Actions CIG NeuProbes (PCIG11-GA-2012-321582) and the Spanish MINECO through the “Ramon y Cajal” programme (RYC2011-07710), the project FPA2009-09017 and through the Centro de excelencia Severo Ochoa Program under grant SEV-2012-0249. This work was finalized during the stay of EFM at the Aspen Center for Physics, which is supported by the National Science Foundation grant PHY-1066293. This stay was also supported by a grant from the Simons Foundation. ML thanks the IFT UAM/CSIC for the kind hospitality during the early stages of this work. JLP also acknowledges support from the INFN program on Theoretical Astroparticle Physics (TASP) and the grant 2012CPPYP7 (Theoretical Astroparticle Physics) under the program PRIN 2012 funded by the Italian Ministry of Education, University and Research (MIUR

Thermal effects in freeze-in neutrino dark matter production

We present a detailed study of the production of dark matter in the form of a sterile neutrino via freeze-in from decays of heavy right-handed neutrinos. Our treatment accounts for thermal effects in the effective couplings, generated via neutrino mixing, of the new heavy neutrinos with the Standard Model gauge and Higgs bosons and can be applied to several low-energy fermion seesaw scenarios featuring heavy neutrinos in thermal equilibrium with the primordial plasma. We find that the production of dark matter is not as suppressed as to what is found when considering only Standard Model gauge interactions. Our study shows that the freeze-in dark matter production could be efficient

Evaluation of virucidal activity of fabrics using feline coronavirus

Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2) is an enveloped RNA virus responsible for the 2019 coronavirus disease (COVID-19) that represents a global health threat, causing an ongoing pandemic in many countries and territories. WHO recommendations emphasize the importance of all personal protective equipment (PPE) that can interrupt COVID-19 transmission. The textile industry and scientists are developing hygienic fabrics by the addition of or treatment with various antimicrobial and antiviral compounds. Methods for determining the antiviral activity of fabrics are reported in the International Standards Organization (ISO) 18184 (2019) guidelines. Three different fabric samples treated with silver derivate, copper derivative and a not treated cotton fabric used as control were examined and put in contact with a suspension of feline coronavirus (FCoV). After 2 h of incubation a significant decrease of viral titer, as high as 3.25 log10 Tissue Culture Infectious Dose (TCID)50/50 μl, in feline cells was observed in treated fabrics, with respect to not treated fabrics. In this study, we optimized laboratory methods to evaluate the virucidal activity of silver- and copper treated cotton- based fabrics against coronavirus, using FCoV suitable as a surrogate of SARS-CoV-2 but safe for laboratory technicians

Heterogeneities along the 2009 L’Aquila normal fault inferred by the b-value distribution

In this study we map the distribution of the b-value of the Gutenberg-Richter law—as well as complementary seismicity parameters—along the fault responsible for the 2009 MW 6.1 L'Aquila earthquake. We perform the calculations for two independent aftershock sub-catalogs, before and after a stable magnitude of completeness is reached. We find a substantial spatial variability of the b-values, which range from 0.6 to 1.3 over the fault plane. The comparison between the spatial distribution of the b-values and the main-shock slip pattern shows that the largest slip occurs in normal-to-high b-values portion of the fault plane, while low b-value is observed close to the main-shock nucleation. No substantial differences are found in the b-value computed before and after the main-shock struck in the small region of the fault plane populated by foreshocks