Identification of Multiple Hard X-Ray Sources in Solar Flares: A Bayesian Analysis of the 2002 February 20 Event

The hard X-ray emission in a solar flare is typically characterized by a number of discrete sources, each with its own spectral, temporal, and spatial variability. Establishing the relationship among these sources is critical to determining the role of each in the energy release and transport processes that occur within the flare. In this paper we present a novel method to identify and characterize each source of hard X-ray emission. The\uf0a0method permits a quantitative determination of the most likely number of subsources present, and of the relative probabilities that the hard X-ray emission in a given subregion of the flare is represented by a complicated multiple source structure or by a simpler single source. We apply the method to a well-studied flare on 2002 February 20 in order to assess competing claims as to the number of chromospheric footpoint sources present, and hence to the complexity of the underlying magnetic geometry/topology. Contrary to previous claims of the need for multiple sources to account for the chromospheric hard X-ray emission at different locations and times, we find that a simple two-footpoint-plus-coronal-source model is the most probable explanation for the data. We also find that one of the footpoint sources moves quite rapidly throughout the event, a factor that presumably complicated previous analyses. The inferred velocity of the footpoint corresponds to a very high induced electric field, compatible with the fields in thin reconnecting current sheets

Stelle di mezzo secolo: divismo e rappresentazione della sessualità nel cinema italiano (1948-1978)

Special issue on Italian stardom and sexuality

Monitoring COVID-19 transmission risks by quantitative real-time PCR tracing of droplets in hospital and living environments

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) environmental contamination occurs through droplets and biological fluids released in the surroundings from patients or asymptomatic carriers. Surfaces and objects contaminated by saliva or nose secretions represent a risk for indirect transmission of coronavirus disease 2019 (COVID-19). We assayed surfaces from hospital and living spaces to identify the presence of viral RNA and the spread of fomites in the environment. Anthropic contamination by droplets and biological fluids was monitored by detecting the microbiota signature using multiplex quantitative real-time PCR (qPCR) on selected species and massive sequencing on 16S amplicons. A total of 92 samples (flocked swabs) were collected from critical areas during the pandemic, including indoor (three hospitals and three public buildings) and outdoor surfaces exposed to anthropic contamination (handles and handrails, playgrounds). Traces of biological fluids were frequently detected in spaces open to the public and on objects that are touched with the hands (.80%). However, viral RNA was not detected in hospital wards or other indoor and outdoor surfaces either in the air system of a COVID hospital but only in the surroundings of an infected patient, in consistent association with droplet traces and fomites. Handled objects accumulated the highest level of multiple contaminations by saliva, nose secretions, and fecal traces, further supporting the priority role of handwashing in prevention. In conclusion, anthropic contamination by droplets and biological fluids is widespread in spaces open to the public and can be traced by qPCR. Monitoring fomites can support evaluation of indirect transmission risks for coronavirus or other flu-like viruses in the environment

Identificazione molecolare di mutazioni conferenti resistenza a rifampicina ed isoniazide in M. tuberculosis in campioni clinici diretti mediante Genotype MTBDR (Hain Lifescience)

The widespread of multi-drug resistant (MDR) Mycobacterium tuberculosis, resistant at least to rifampin (RIF) and isoniazid (INH), represents serious threats to the control of tuberculosis (TB) and increases the public health challenge worldwide. Surveillance program and rapid identification of drug-resistance strains are key-elements for an early and appropriate TB management. The aim is to evaluate the Genotype MTBDR (Hain Lifescience, Nehren, Germany), a reverse hybridization-based assay, as a rapid tool to identify mutations in the rpoB and katG genes associated to RIF-/INH-resistance directly in clinical specimens.We also evaluate the performance of a paper based device (Genocard – Hain Lifescience, Nehren, Germany) to collect and transport inactivated biological material. The test was evaluated retrospectively on 68 respiratory samples with positive cultures for M. tuberculosis. Considering the smear-positive samples only, the Genotype MTBDR gave interpretable results in 56 out of 57 samples (98.2%). The main limitations of the Genotype MTBDR are the difficulties in the amplification from smear-negative samples and the low sensitivity for the INH-resistance. The inclusion of probes targeting other regions involved in INH-resistance will increase the sensitivity of the test. The GenoCard, with its easy- and rapid-to use features, represents a functional tool for the sample collection with cost-effective and bio-safety benefits.The possibility to use the GenoCard directly in amplification reactions facilitates the gathering of data by molecular approaches

Use of Genotype MTBDR Assay for Molecular Detection of Rifampin and Isoniazid Resistance in Mycobacterium tuberculosis Clinical Strains Isolated in Italy

Mycobacterium tuberculosis is one of the leading causes of death worldwide, and multidrug-resistant tuberculosis (MDR-TB) is associated with a high case fatality rate. Rapid identification of resistant strains is crucial for the early administration of appropriate therapy, for prevention of development of further resistance, and to curtail the spread of MDR strains. The Genotype MTBDR (Hain Lifescience, Nehren, Germany) is a reverse hybridization line probe assay designed for the rapid detection of rpoB and katG gene mutations in clinical isolates. The ability of this technique to correctly identify resistant and MDR-TB strains was tested on 206 isolates from the Italian drug resistance surveillance system. This panel included the majority of MDR strains isolated in Italy in the past 3 years. The results of the test were compared to conventional drug susceptibility test performed on isolated strains and verified by sequencing the regions of interest of the bacterial genome. The rate of concordance between the results of the MTBDR and those obtained with “in vitro” sensitivity was 91.5% (130 of 142) for rifampin and 67.1% (116 of 173) for isoniazid. We also applied this test directly to a panel of 36 clinical specimens collected from patients with active TB. The MTBDR correctly identified the two cases of MDR-TB included in the panel. These results show that the MTBDR test is useful in the detection and management of tuberculosis when MDR disease is suspected