The imprint of dark matter haloes on the size and velocity dispersion evolution of early-type galaxies

Early-type galaxies (ETGs) are observed to be more compact, on average, at $z \gtrsim 2$ than at $z\simeq 0$, at fixed stellar mass. Recent observational works suggest that such size evolution could reflect the similar evolution of the host dark matter halo density as a function of the time of galaxy quenching. We explore this hypothesis by studying the distribution of halo central velocity dispersion ($\sigma_0$) and half-mass radius ($r_{\rm h}$) as functions of halo mass $M$ and redshift $z$, in a cosmological $\Lambda$-CDM $N$-body simulation. In the range $0\lesssim z\lesssim 2.5$, we find $\sigma_0\propto M^{0.31-0.37}$ and $r_{\rm h}\propto M^{0.28-0.32}$, close to the values expected for homologous virialized systems. At fixed $M$ in the range $10^{11} M_\odot \lesssim M\lesssim 5.5 \times 10^{14} M_\odot$ we find $\sigma_0\propto(1+z)^{0.35}$ and $r_{\rm h}\propto(1+z)^{-0.7}$. We show that such evolution of the halo scaling laws is driven by individual haloes growing in mass following the evolutionary tracks $\sigma_0\propto M^{0.2}$ and $r_{\rm h}\propto M^{0.6}$, consistent with simple dissipationless merging models in which the encounter orbital energy is accounted for. We compare the $N$-body data with ETGs observed at $0\lesssim z\lesssim3$ by populating the haloes with a stellar component under simple but justified assumptions: the resulting galaxies evolve consistently with the observed ETGs up to $z \simeq 2$, but the model has difficulty reproducing the fast evolution observed at $z\gtrsim 2$. We conclude that a substantial fraction of the size evolution of ETGs can be ascribed to a systematic dependence on redshift of the dark matter haloes structural properties.Comment: 15 pages, 14 figures, 1 table. Matches the Accepted version from MNRA

SARS-CoV-2 infection serology: a useful tool to overcome lockdown?

The outbreak of 2019 novel coronavirus disease (Covid-19) caused by SARS-CoV-2 has spread rapidly, inducing a progressive growth in infected patients number. Social isolation (lockdown) has been assessed to prevent and control virus diffusion, leading to a worldwide financial and political crisis. Currently, SARS-CoV-2 RNA detection in nasopharyngeal swab takes place by real-time PCR (RT-qPCR). However, molecular tests can give some false-negative results. In this context, serological assays can be useful to detect IgG/IgM antibodies, to assess the degree of immunization, to trace the contacts, and to support the decision to re-admit people at work. A lot of serological diagnostic kits have been proposed on the market but validation studies have not been published for many of them. The aim of our work was to compare and to evaluate different assays analytical performances (two different immunochromatographic cards, an immunofluorescence chromatographic card, and a chemiluminescence-automated immunoassay) on 43 positive samples with RT-qPCR-confirmed SARS-CoV-2 infection and 40 negative control subjects. Our data display excellent IgG/IgM specificities for all the immunocromatographic card tests (100% IgG and 100% IgM) and for the chemiluminescence-automated assay (100% IgG and 94% IgM); IgG/IgM sensitivities are moderately lower for all methods, probably due to the assay viral antigen's nature and/or to the detection time of nasopharyngeal swab RT-qPCR, with respect to symptoms onset. Given that sensitivities (around 94% and 84% for IgG and IgM, respectively) implicate false-negative cases and given the lack of effective vaccines or treatments, the only currently available procedure to reduce SARS-CoV-2 transmission is to identify and isolate persons who are contagious. For this reason, we would like to submit a flowchart in which serological tests, integrated with nasopharyngeal swab RT-qPCR, are included to help social and work activities implementation after the pandemic acute phase and to overcome lockdown

Cytomegalovirus Glycoprotein B Genotype Distribution in Italian Transplant Patients.

Background: The cytomegalovirus (CMV) UL55 gene encodes for a glycoprotein implicated in virus pathogenesis. Based on UL55 polymorphism, CMV has been divided into 4 genotypes. Previous studies investigated the possible role of genotypes in the clinical outcome of infection in different categories of patients; however, few data are available, particularly in the transplant setting and Italian case records. Methods: Phylogenetic analysis through a maximum likelihood tree was used to evaluate the prevalence and distribution of CMV genotypes in whole blood specimens from 47 transplant patients and investigate the relation with demographic and clinical features. Results: Overall, 40.4% of patients were classified as single genotype (12.8% gB1, 23.4% gB2, 4.2% gB3); mixed genotypes were detected in 59.6%. Genotype 4 was detected only in mixed cases. In comparison to single genotypes, mixed genotypes were more frequently associated with a higher duration of DNA viremia and higher peak viral load. Conclusions: Mixed infections seem to be prevalent in Italian transplant patients; it is likely that mixed infections are more difficult to control by immunological response in comparison to single genotype infections. In this context, the genetic profile of infecting viruses and relation to clinical outcome should be investigated, also taking into account the CMV-specific cellular immune response

Methodology for assessment of public health emergency preparedness and response synergies between institutional authorities and communities

Background: This paper describes a participatory methodology that supports investigation of the synergistic collaboration between communities affected by infectious disease outbreak events and relevant official institutions. The core principle underlying the methodology is the recognition that synergistic relationships, characterised by mutual trust and respect, between affected communities and official institutions provide the most effective means of addressing outbreak situations. Methods: The methodological approach and lessons learned were derived from four qualitative case studies including (i) two tick-borne disease events (Crimean-Congo haemorrhagic fever in Spain, 2016, and tick-borne encephalitis in the Netherlands, 2016); and (ii) two outbreaks of acute gastroenteritis (norovirus in Iceland, 2017, and verocytotoxin-producing Escherichia coli [VTEC] in Ireland, 2018). An after-event qualitative case study approach was taken using mixed methods. The studies were conducted in collaboration with the respective national public health authorities in the affected countries by the European Centre for Disease Prevention and Control (ECDC). The analysis focused on the specific actions undertaken by the participating countries' public health and other authorities in relation to community engagement, as well as the view from the perspective of affected communities. Results: Lessons highlight the critical importance of collaborating with ECDC National Focal Points during preparation and planning and with anthropological experts. Field work for each case study was conducted over one working week, which although limiting the number of individuals and institutions involved, still allowed for rich data collection due to the close collaboration with local authorities. The methodology enabled efficient extraction of synergies between authorities and communities. Implementing the methodology required a reflexivity among fieldworkers that ackowledges that different versions of reality can co-exist in the social domain. The method allowed for potential generalisability across studies. Issues of extra attention included insider-outsider perspectives, politically sensitivity of findings, and how to deal with ethical and language issues. Conclusions: The overall objective of the assessment is to identify synergies between institutional decision-making bodies and community actors and networks before, during and after an outbreak response to a given public health emergency. The methodology is generic and could be applied to a range of public health emergencies, zoonotic or otherwise

MISSEL: a method to identify a large number of small species-specific genomic subsequences and its application to viruses classification

Continuous improvements in next generation sequencing technologies led to ever-increasing collections of genomic sequences, which have not been easily characterized by biologists, and whose analysis requires huge computational effort. The classification of species emerged as one of the main applications of DNA analysis and has been addressed with several approaches, e.g., multiple alignments-, phylogenetic trees-, statistical- and character-based methods

Phylogenesis and Clinical Aspects of Pandemic 2009 Influenza A (H1N1) Virus Infection

During the spring of 2009, a new influenza A (H1N1) virus of swine origin emerged and spread worldwide causing a pandemic influenza. Here, 329 naso-pharyngeal swabs collected from patients with flu-like symptoms were analyzed by real-time PCR for the presence of H1N1 2009 pandemic virus. Twenty-five samples collected from immunocompetent and immunodepressed patients contained the H1N1 pandemic virus. Phylogenetic analysis of the hemagglutinin and neuraminidase genes showed no obvious differences in terms of similarity and/or homology between the sequences identified in immunocompetent individuals and those obtained from immunocompromised patients. Pre-existing clinical conditions may influence the outcome of H1N1 disease

Accretion onto Intermediate Mass Black Holes Regulated by Radiative Feedback I. Parametric Study for Spherically Symmetric Accretion

We study the effect of radiative feedback on accretion onto intermediate mass black holes (IMBHs) using the hydrodynamical code ZEUS-MP with a radiative transfer algorithm. In this paper, the first of a series, we assume accretion from a uniformly dense gas with zero angular momentum and extremely low metallicity. Our 1D and 2D simulations explore how X-ray and UV radiation emitted near the black hole regulates the gas supply from large scales. Both 1D and 2D simulations show similar accretion rate and period between peaks in accretion, meaning that the hydro-instabilities that develop in 2D simulations do not affect the mean flow properties. We present a suite of simulations exploring accretion across a large parameter space, including different radiative efficiencies and radiation spectra, black hole masses, density and temperature, $T_\infty$, of the neighboring gas. In agreement with previous studies we find regular oscillatory behavior of the accretion rate, with duty cycle $\sim 6$, mean accretion rate 3% $(T_{\infty}/10^4 {\rm K})^{2.5}$ of the Bondi rate and peak accretion $\sim 10$ times the mean for $T_{\infty}$ ranging between 3000K and 15000K. We derive parametric formulas for the period between bursts, the mean accretion rate and the peak luminosity of the bursts and thus provide a formulation of how feedback regulated accretion operates. The temperature profile of the hot ionized gas is crucial in determining the accretion rate, while the period of the bursts is proportional to the mean size of the Str\"{o}mgren sphere and we find qualitatively different modes of accretion in the high vs. low density regimes. We also find that softer spectrum of radiation produces higher mean accretion rate.Comment: 16 pages, 12 figures, accepted for publication in Ap

Evaluation of S-RBD and high specificity ACE-2-binding antibodies on SARS-CoV-2 patients after six months from infection

The antibody response to SARS-CoV-2 has not yet fully defined, but the availability of sensitive and specific serological assays is crucial to observe the presence of specific antibodies against the human receptor binding domain (S-RBD) and high specificity ACE-2-binding antibodies or neutralizing antibodies (NT) in response to vaccines. Indeed, these peculiar antibodies should prevent viral interaction between RBD and AngiotensinConverting Enzyme 2 (ACE2) receptor, located on surface of host cells. In this study, 72 samples from 37 hospitalized COVID-19 patients and 35 not-hospitalized patients were analyzed longitudinally. The detection of SRBD and NT antibodies was carried out using CLIA tests. Hospitalized patients showed elevated serum levels of S-RBD (97.22%) and NT (77.78%) antibodies, differently, not-hospitalized, who were paucisymptomatic or asymptomatic patients, showed lower serum levels of SRBD (65.71%) and NT (38.14%) antibodies. The results suggest that the NT serum level is strongly related to disease severity (p < 0.001) and to the serum level of S-RBD antibodies (p < 0.0001)

Viral hepatitis, HIV, human herpes virus and Treponema pallidum infection in haemodialysis patients from Kosovo, 2005.

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