Slices of the unitary spread

We prove that slices of the unitary spread of Q(+)(7, q), q equivalent to 2 (mod 3), can be partitioned into five disjoint classes. Slices belonging to different classes are non-equivalent under the action of the subgroup of P Gamma O+(8, q) fixing the unitary spread. When q is even, there is a connection between spreads of Q(+)(7, q) and symplectic 2-spreads of PG(5, q) (see Dillon, Ph.D. thesis, 1974 and Dye, Ann. Mat. Pura Appl. (4) 114, 173-194, 1977). As a consequence of the above result we determine all the possible non-equivalent symplectic 2-spreads arising from the unitary spread of Q(+)(7, q), q = 2(2h+1). Some of these already appeared in Kantor, SIAM J. Algebr. Discrete Methods 3(2), 151-165, 1982. When q = 3(h), we classify, up to the action of the stabilizer in P Gamma O(7, q) of the unitary spread of Q(6, q), those among its slices producing spreads of the elliptic quadric Q(-)(5, q)

Groups and clusters of galaxies in the XXL survey

This thesis presents one of the first census of the properties of galaxies in X-ray selected groups and clusters at intermediate redshift, with the aim of assessing the role of envi- ronment on the galaxy stellar mass assembly, star formation activity and observed stellar population properties. My project is framed in the XXL Survey (Pierre et al. 2016), the largest XMM-Newton programme approved to date, covering two extragalactic regions in the sky of 25 deg2 each one. Extended X-ray sources identified as groups and clusters are spectroscopically confirmed and their main properties are characterised either via direct measurements or by means of scaling relations. Among them, inferred X-ray luminosities and temperatures, virial masses and radii are of fundamental importance for the development of this thesis. The great advantage of XXL is that the XXL-North field (XXL-N) is fully covered by photometric and spectroscopic observations coming from the most recent extragalactic surveys of galaxies. The availability of such a treasure trove of information motivates the development of my research on galaxy populations at 0.1≤z≤0.6 in XXL-N, exploring the most diverse environments ranging from the field, to groups, clusters and superclusters. The first task of my work consists in the creation of a homogeneous spectrophotometric sample of galaxies, released in Guglielmo et al. (2017), suitable for scientific purposes. The catalogue contains spectroscopic redshifts, membership information on groups and clus- ters, spectroscopic completeness weights as a function of position in the sky and observed magnitude, stellar masses and absolute magnitudes computed by means of a spectral en- ergy distribution (SED) technique. The catalogue is fundamental for all XXL studies that aims at relating optical properties derived from galaxies with X-ray information and is widely used in the whole XXL collaboration. The released spectrophotometric catalogue enables the first scientific achievement of this thesis regarding the study of the galaxy stellar mass function (GSMF). The goal of this analysis is to unveil whether the mass assembly of galaxies depends on global environment, i.e. field vs groups and clusters and, among groups and clusters, on X-ray luminosity, used as a proxy for the halo mass. I performed the analysis in four redshift bins in the range 0.1≤z≤0.6, finding overall that environment does not affect the GSMF, at least in the mass range probed. The result is further confirmed by the invariance of the mean mass of member galaxies on X-ray luminosity. I also looked into the evolution of the mass assembly from z=0.6 down to z=0.1, finding that the high mass end is already in place at the oldest epoch and does not evolve and detecting an increase in the low-mass galaxy population in the same redshift range. This study is one of the first systematic studies on the GSMF conducted for X-ray extended sources ranging from the group to the cluster environment, and is published in the second part of Guglielmo et al. (2017). Having assessed the independence of the mass distributions on the global environment, I proceed investigating whether and to what extent the environment affects the star formation activity and the observed properties of the galaxy stellar populations. I started this analysis from the richest supercluster identified in XXL-N, XLSSsC N01, located at redshift z∼0.3 and composed of 14 groups and clusters. This work has been submitted in Guglielmo et al. (2018a). With focus on the region surrounding XLSSsC N01, I divided galaxies in different environments, ranging from the virial regions of groups and clusters to the field, using a combination of global and local environment parametri- sations. The main results of this study are that, in the supercluster environment, while the star forming fractions and quenching efficiency strongly depend on environment, the SFR-mass relation does not. The star forming fraction progressively declines from the field to filaments to the virialised regions of groups and clusters, with an interesting en- hancement in the outer regions of the X-ray structures. Moreover, while the average luminosity weighted (LW)-age-mass relation is independent of the environment, a clear signature for recent star formation quenching is found in the stellar ages of passive galaxies in the virialised regions of X-ray structures. Finally, I extend the analysis of this peculiar supercluster to the whole XXL-N field. This work will be enclosed in two articles in preparation (Guglielmo et al. 2018 b,c in prep.). Thanks to the higher statistics of the entire sample, I investigated the properties of galaxies and their evolution at 0.1≤z≤0.5 in different environments, with the goal of characterising the changing in the stellar population properties and the build up of the passive population via environmental quenching. Besides distinguishing among galaxies in the field, and in groups and clusters (virial regions and outskirts), I also focused on galaxies located in structures of different X-ray luminosity and in galaxies located within superclusters. Simultaneously, I also investigated the properties of galaxies located at different projected local densities (LD). In particular, I characterised the fraction of star forming/blue galaxies and of the SFR- mass relation, as a function of both global and local environment. The fraction of star forming and blue galaxies is strictly related to the environment, having the lowest value in the virial regions of groups and clusters, and the highest in the field. In outer members, the same fraction is similar to that in the field at z≥0.2, and assumes intermediate values with respect to virial members and the field at 0.1≤z<0.2. The SFR-mass relation is also environment dependent, and in particular the number of virial member galaxies having reduced SFR (galaxies in transition) nearly doubles that of field galaxies. Again, outer members show intermediate properties: the fraction of galaxies in transition is similar to the virial population at z>0.3, when it is found to be associated to the supercluster environment, and then reduces to values typical of field galaxies at 0.1≤z<0.3. The star forming and blue fractions also decrease with increasing LD at all redshifts. On the contrary, the fraction of galaxies in transition does not vary in the same LD range. These significant differences emerging among the global and local environments are intrinsically related to the different physical meaning of the two parametrisations, thus to the different physical mechanisms acting on galaxies when bound in the potential well of a dark matter halo (according to the global definition) or when exposed to interactions with other galaxies in over dense and highly populated regions (according to the local definition). During the first stages of my PhD, I also completed the analysis of my master thesis, and I report the full text of the published paper in the Appendix of the thesis (Guglielmo et al. 2015). The results are closely related to the scientific questions tackled in my PhD project, addressed through a complementary approach that reconstructed the star formation history of low- redshift galaxies in clusters and in the field to study the dependence on global environment, stellar mass and observed morphology

The star formation history of galaxies: the role of galaxy mass, morphology and environment

We analyze the star formation history (SFH) of galaxies as a function of present-day environment, galaxy stellar mass and morphology. The SFH is derived by means of a non-parametric spectrophotometric model applied to individual galaxies at z ~ 0.04- 0.1 in the WINGS clusters and the PM2GC field. The field reconstructed evolution of the star formation rate density (SFRD) follows the values observed at each redshift (Madau & Dickinson 2014), except at z > 2 where our estimate is ~ 1.7x higher than the high-z observed value. The slope of the SFRD decline with time gets progressively steeper going from low mass to high mass haloes. The decrease of the SFRD since z = 2 is due to 1) quenching - 50% of the SFRD in the field and 75% in clusters at z > 2 originated in galaxies that are passive today - and 2) the fact that the average SFR of today's star-forming galaxies has decreased with time. We quantify the contribution to the SFRD(z) of galaxies of today's different masses and morphologies. The current morphology correlates with the current star formation activity but is irrelevant for the past stellar history. The average SFH depends on galaxy mass, but galaxies of a given mass have different histories depending on their environment. We conclude that the variation of the SFRD(z) with environment is not driven by different distributions of galaxy masses and morphologies in clusters and field, and must be due to an accelerated formation in high mass haloes compared to low mass ones even for galaxies that will end up having the same galaxy mass today.Comment: 16 pages, 10 figures. Published on MNRA

Druggable monogenic immune defects hidden in diverse medical specialties: Focus on overlap syndromes

In the last two decades two new paradigms changed our way of perceiving primary immunodeficiencies: An increasing number of immune defects are more associated with inflammatory or autoimmune features rather than with infections. Some primary immune defects are due to hyperactive pathways that can be targeted by specific inhibitors, providing innovative precision treatments that can change the natural history of diseases. In this article we review some of these "druggable" inborn errors of immunity and describe how they can be suspected and diagnosed in diverse pediatric and adult medicine specialties. Since the availability of precision treatments can dramatically impact the course of these diseases, preventing the development of organ damage, it is crucial to widen the awareness of these conditions and to provide practical hints for a prompt detection and cure

World Caf\ue9 at Summer School of WHO Collaborating Centre for Epidemiology and Community Dentistry

Objectives of the study: This study is a qualitative evaluation of a teaching method. The 2015 Summer School organized by the WHO Collaborating Centre for Epidemiology and Community Dentistry of Milan took place in Sardinia. The educational objectives of the first day included: make an informal conversation with other members of the summer school; create an interesting exchange of ideas and experiences also between new, \u201chabitue\u301\u201d and beginners with senior professionals of this event; make a group for the works in the next days. Considering the different professional roles, age and context of origin, the purpose of the Pedagogists was to create a positive, relaxed but intimate atmosphere using the pleasure of \u201cinformal\u201d conversation, through a creative and practical method: The World Cafe\u300. Materials &amp; methods: The Pedagogists\u2019 first task focused on: caring of the location and the physical setup of the table, creating relevant questions to the concerns of the group, establishing the rules, managing the process to encourage participants to have a non- formal learning experience consequently improving thinking, speaking and listening skills. Finally the participants answered self-administered questionnaire to write about their emotions and cognitive processes that went out during the World Cafe\u300. Results: The analysis of the questionnaires was carried out with Interpretative Phenomenological Analysis (IPA), The interpretative steps identified two emerging themes: \u201cdifferent vs peer\u201d and \u201cdiscovering vs practicing\u201d. Conclusions: The World Cafe\u301 experience improves learning by connection; thinking and learning become dynamic processes instead of learning outcomes

Modulation of Mechanosensitive Potassium Channels by a Membrane-targeted Nongenetic Photoswitch

Mechanosensitive ion channels are present in the plasma membranes of all cells. They play a fundamental role in converting mechanical stimuli into biochemical signals and are involved in several physiological processes such as touch sensation, hearing, and blood pressure regulation. This protein family includes TWIK-related arachidonic acid-stimulated K+ channel (TRAAK), which is specifically implicated in the maintenance of the resting membrane potential and in the regulation of a variety of important neurobiological functions. Dysregulation of these channels has been linked to various diseases, including blindness, epilepsy, cardiac arrhythmia, and chronic pain. For these reasons, mechanosensitive channels are targets for the treatment of several diseases. Here, we propose a new approach to investigate TRAAK ion channel modulation that is based on nongenetic photostimulation. We employed an amphiphilic azobenzene, named Ziapin2. In the dark, Ziapin2 preferentially dwells in the plasma membrane, causing a thinning of the membrane. Upon light irradiation, an isomerization occurs, breaking the dimers and inducing membrane relaxation. To study the effect of Ziapin2 on the mechanosensitive channels, we expressed human TRAAK (hTRAAK) channels in HEK293T cells. We observed that Ziapin2 insertion in the membrane is able per se to recruit hTRAAK, permitting the exit of K+ ions outside the cells with a consequent hyperpolarization of the cell membrane. During light stimulation, membrane relaxation induces hTRAAK closure, generating a consistent and compensatory depolarization. These results add information to the Ziapin2 mechanism and suggest that membrane deformation can be a tool for the nonselective modulation of mechanosensitive channels

Health Literacy, Socioeconomic Status and Vaccination Uptake: A Study on Influenza Vaccination in a Population-Based Sample

Background: Health Literacy (HL) has been recently hypothesized to affect the relationship between socio-economic status (SES) and health conditions. However, to date no study has yet assessed the potential contribution of HL in the pathway through which SES affects influenza vaccination status. We aim to examine the relationships among HL, SES factors, and influenza vaccination uptake in Tuscan (Italy) residents belonging to different high-risk groups (HRGs) for influenza. Methods: The study was performed within the Tuscan population sample selected in the Italian Behavioral Risk Factor Surveillance System in 2017–2018. HL was assessed using the Italian version of the 6-items European Health Literacy Survey Questionnaire (HLS-EU-Q6). Mediation analyses were conducted using SES variables as independent variables, influenza vaccination status as dependent variable and HL as mediator variable. Results: A total of 3278 people belonged to HRGs for influenza. In the whole sample, 19.4% of the participants were vaccinated against influenza. Participants who were not employed or had a poor financial status were more likely to be vaccinated against influenza (OR 1.56, 95%CI 1.26–1.94, p < 0.001, and OR 1.21, 95%CI 1.00–1.48, p = 0.047 respectively). HL did not mediate the relationship of any of the independent variables with influenza vaccination status. Conclusions: Some SES determinants resulted to influence influenza vaccination uptake, while HL did not affect the likelihood of influenza vaccination uptake among HRGs. Universal health care systems, as in the case of Italy, offering influenza vaccination free of charge to HRGs help in reducing inequalities and mitigating HL demands