Testing pre-main sequence models: the power of a Bayesian approach

Pre-main sequence (PMS) models provide invaluable tools for the study of star forming regions as they allow to assign masses and ages to young stars. Thus it is of primary importance to test the models against observations of PMS stars with dynamically determined mass. We developed a Bayesian method for testing the present generation of PMS models which allows for a quantitative comparison with observations, largely superseding the widely used isochrones and tracks qualitative superposition. Using the available PMS data we tested the newest PISA PMS models establishing their good agreement with the observations. The data cover a mass range from ~0.3 to ~3.1 Msun, temperatures from ~3x10^3 to ~1.2x10^4 K and luminosities from ~3x10^-2 to ~60 Lsun. Masses are correctly predicted within 20% of the observed values in most of the cases and for some of them the difference is as small as 5%. Nevertheless some discrepancies are also observed and critically discussed. By means of simulations, using typical observational errors, we evaluated the spread of log \tau_sim - log \tau_rec, i.e. simulated minus recovered ages distribution of the single objects. We also found that stars in binary systems simulated as coeval might be recovered as non coeval, due to observational errors. The actual fraction of fake non coevality is a complex function of the simulated ages, masses and mass ratios. We demonstrated that it is possible to recover the systems' ages with better precision than for single stars using the composite age-probability distribution, i.e. the product of the components' age distributions. Using this valuable tool we estimated the ages of the presently observed PMS binary systems.Comment: Accepted for publication in MNRAS. Fig.2 presented in low-resolution in this versio

Testing and modelling a semi-actively controlled steel frame structure equipped with MR dampers

In this paper, analysis of the shaking table tests performed on a four storey, large-scale, steel mock-up, equipped with a bracing system including magnetorheological (MR) dampers operating both in passive and semi-active (SA) ON–OFF mode, is presented. The adopted SA control algorithm is derived from an 'energy-based' instantaneous optimal control process. After having described the testing set-up and the control algorithm, a critical overview of the experimental results is reported. In particular, by using SA-controlled MR dampers, large response reductions, with respect to the corresponding passive (ON state) control configuration, may be obtained both in terms of relative displacements (drifts) and absolute accelerations. Moreover, it is experimentally confirmed that use of SA control, not only reduces the maximum values of the considered response quantities, but extends the improvements to the complete time-histories. This satisfactory performance is obtained, even if some particular (and undesired) types of behaviour, shown and explained in the paper, have been detected during the test campaign. In order to completely understand the dynamical behaviour of the controlled structure and to predict its response, a detailed analytical model of the controlled mock-up is proposed and validated. Copyright © 2004 John Wiley & Sons, Ltd

The phosphorylation of protein S6 modulates the interaction of the 40 S ribosomal subunit with the 5'-untranslated region of a dictyostelium pre-spore-specific mRNA and controls its stability.

AC914 mRNA, a pre-spore-specific mRNA that accumulates only in the post-aggregation stage of development, is transcribed constitutively as shown by nuclear run-off experiments and by fusing its promoter to the luciferase reporter gene. The same mRNA disappears quickly from disaggregated cells. If the 5'-untranslated region (5'UTR) of the constitutively expressed Actin 15 mRNA is substituted for the 5'UTR of AC914 mRNA, this can no longer be destabilized and accumulates both in growing and disaggregated cells. If the 5'UTR of AC914 mRNA is substituted for the 5'UTR of Actin 15 mRNA, the latter accumulates only in aggregated cells. Pactamycin, but not other inhibitors of protein synthesis, prevents AC914 mRNA from being destabilized in disaggregated cells, suggesting a role of 40 S subunits in the destabilization. This has been confirmed by using an in vitro system in which the in vivo stability of different mRNAs is reproduced. A protein kinase A-dependent phosphorylation of ribosomal protein S6 determines whether 40 S subunits are capable or not of destabilizing AC914 mRNA in the in vitro system

Spatially resolved Fe K spectroscopy of NGC 4945

We present the imaging and spectroscopic analysis of the combined Chandra ACIS-S observations of the Compton-thick Seyfert 2 galaxy NGC 4945. We performed a spatially-resolved spectroscopy of the circumnuclear environment of the source, picturing the innermost 200 parsecs around the highly absorbed nucleus. The additional 200 ks ACIS-S data with respect to the previous campaign allowed us to map with even greater detail the central structure of this source and to discover an enhanced iron emission in the innermost nuclear region, with respect to the associated Compton reflection continuum. We revealed that the Equivalent Width of the iron K$\alpha$ line is spatially variable (ranging from 0.5 to 3 keV), on scales of tens of parsecs, likely due to the ionization state and orientation effects of the reprocessing material, with respect to the central X-ray illuminating source. A clump of highly ionized Fe XXV He-$\alpha$ is also detected, 40 parsecs east to the nucleus. When observations taken years apart are considered, the central unresolved reflected emission is found to remain constant.Comment: 10 pages, 6 figures, 4 tables, accepted for publication in MNRA

The Clinical Relevance of Gastroesophageal Reflux Disease and Laryngopharyngeal Reflux in Clinical Practice

Gastric reflux may be considered a para-physiological event that may occur up to 50 times a day. It usually happens when gas (less commonly liquids) flow back from stomach into esophagus. However, when defense mechanisms leave, disease may progress. If the esophagus is the trigger, gastroesophageal reflux disease (GERD) emerges. The prevalence of GERD in the primary care setting seems to be even more evident when one considers that, in the United States, 4.6 million office encounters annually are primarily for GERD, whereas 9.1 million encounters include GERD in the top 3 diagnoses for the encounter. GERD constitutes also the most frequently first-listed gastrointestinal diagnosis in ambulatory care visits. In addition, the extraesophageal manifestations of reflux, including LPR, asthma, and chronic cough, have been estimated to cost $5438 per patient in direct medical expenses in the first year after presentation and$13,700 for 5 years. Presently, the newest alginate compounds renowned the interest in this attracting and stimulating area. In this regard, a new medical device (Marial®), unique still now possessing the indication for both GERD and LPR, has been recently launched in the Italian market, two large surveys were conducted in Italy: RELIEF, involving 86 otolaryngologists, and EMERGE, involving 56 gastroenterologists. The aims of these surveys were: (1) to define clinical characteristics, including previous treatment, of the patients referred to consultation; (2) to evaluate the reliability of RFS, GIS, and RSI questionnaires in real-world settings, such as specialist office; and (3) to investigate the patients’ perception of efficacy of the prescribed therapy, based on the best practice and considering also the new medical device Comparing the patients’ perception of treatment efficacy, reduction in RSI values for each single symptom before and after a 4 week-treatment with Marial® alone or with PPI in add-on in EMERGE and RELIEF patients are reported. Marial® alone treatment induced a statistically significant higher reduction in each single symptom in RELIEF patients than in EMERGE patients, with the exception of heartburn, chest pain, indigestion, or stomach acid coming up. Similar results were obtained evaluating the reduction in RSI values in patients treated with PPI in add-on that was able to determine a higher statistically significant decrease in RELIEF than in EMERGE patients in each single symptom, with the exception of heartburn, chest pain, indigestion, or stomach acid coming up

Adversarial Attacks Against Uncertainty Quantification

Machine-learning models can be fooled by adversarial examples, i.e., carefully-crafted input perturbations that force models to output wrong predictions. While uncertainty quantification has been recently proposed to detect adversarial inputs, under the assumption that such attacks exhibit a higher prediction uncertainty than pristine data, it has been shown that adaptive attacks specifically aimed at reducing also the uncertainty estimate can easily bypass this defense mechanism. In this work, we focus on a different adversarial scenario in which the attacker is still interested in manipulating the uncertainty estimate, but regardless of the correctness of the prediction; in particular, the goal is to undermine the use of machine-learning models when their outputs are consumed by a downstream module or by a human operator. Following such direction, we: \textit{(i)} design a threat model for attacks targeting uncertainty quantification; \textit{(ii)} devise different attack strategies on conceptually different UQ techniques spanning for both classification and semantic segmentation problems; \textit{(iii)} conduct a first complete and extensive analysis to compare the differences between some of the most employed UQ approaches under attack. Our extensive experimental analysis shows that our attacks are more effective in manipulating uncertainty quantification measures than attacks aimed to also induce misclassifications

Single stars in the Hyades open cluster. Fiducial sequence for testing stellar and atmospheric models

Age and mass determinations for isolated stellar objects remain model-dependent. While stellar interior and atmospheric theoretical models are rapidly evolving, we need a powerful tool to test them. Open clusters are good candidates for this role. We complement previous studies on the Hyades multiplicity by Lucky Imaging observations with the AstraLux Norte camera. This allows us to exclude possible binary and multiple systems with companions outside 2--7 AU separation and to create a "single-star sequence" for the Hyades. The sequence encompasses 250 main-sequence stars ranging from A5V to M6V. Using the "Tool for Astrophysical Data Analysis" (TA-DA), we create various theoretical isochrones applying different combinations of interior and atmospheric models. We compare the isochrones with the observed Hyades single-star sequence on J vs. J - K_s, J vs. J - H and K_s vs. H - K_s color-magnitude diagrams. As a reference we also compute absolute fluxes and magnitudes for all stars from X-ray to mid-infrared based on photometric measurements available in the literature(ROSAT X-ray, GALEX UV, APASS gri, 2MASS JHK_s, and WISE W1 to W).We find that combinations of both PISA and DARTMOUTH stellar interior models with BT-Settl 2010 atmospheric models describe the observed sequence well. The full sequence covers the mass range 0.13 to 2.3 Msun, and effective temperatures between 3060 K and 8200 K. Within the measurement uncertainties, the current generation of models agree well with the single-star sequence. The primary limitations are the uncertainties in the measurement of the distance to individual Hyades members, and uncertainties in the photometry. Additionally, a small (~0.05 mag) systematic offset can be noted on J vs. J - K and K vs. H - K diagrams - the observed sequence is shifted to redder colors from the theoretical predictions.Comment: 6 pages, 2 figures, 1 table. The extended version of the table will be available online soon. Accepted for publication in Astronomy & Astrophysic

Green Systems Integrated to the Building Envelope: Strategies and Technical Solution for the Italian Case

Green roofs and green and living walls are increasingly seen in cities, because they are an important strategy that addresses some key urban environmental issues and allows the achievement of different benefits. Among these, the most relevant ones are reduction of the \u201cUrban Heat Island\u201d effect, of rainfall contributions to the sewer system, of environmental impact and energy saving, and retention of harmful substance. The study aims to analyze different systems of greenery systems integrated (GSI), green roofs (GR), and green and living walls (GW-LW), as a possible retrofit technique of the envelope of heritage buildings and especially their applications in the context of historic cities in Italy, pointing out positive and negative aspects. Particularly, it pays attention to the green retrofitting of buildings and to the technical problems related to the installation of systems, since at the moment there are already several studies that show the environmental and microclimatic benefits of the integration of vegetation in architecture. This study tries to highlight the series of design procedures necessary both in the preliminary phase and then in the executive phase to relate the GSI to the existing building envelopes. The GR, from the results of the simulations conducted, demonstrate a greater simplicity in their construction, with improvements also from the point of view of the working loads on the existing structures, since the interventions are performed more easily than those on the facade. The study highlights the architectural needs that are not always considered such as the increase in the thickness of the roof and the related need to raise its edges, changing the perspective of the building. On the other hand, the GW and the LW show some complexity in their construction because they must deal with facades often rich in decorative elements and where openings aect the assemblage and connection works such as the tinsmiths of the intrados of the openings. It must be taken into consideration the necessity of having to drill masonry, often inhomogeneous, to connect fixings and the problems of stability this entails must be carefully analyzed