Mitigation of the impact of stellar activity on observations of transiting planets

Il tema centrale della tesi è l'impatto dell'attività stellare sulle osservazioni dei pianeti in transito e sull'identificazione di una metodologia per correggere questi effetti. In particolare, viene approfondito l'effetto delle macchie stellari. La presenza di macchie sul disco stellare visibile può distorcere la curva della luce di transito primaria in modo dipendente dalla lunghezza d'onda, mimando la presenza di un'atmosfera planetaria. Per tener conto di questo effetto, la tesi presenta un metodo innovativo per stimare le proprietà delle macchie e la loro distribuzione dalle osservazioni fuori transito e correggere le curve di luce del transito planetario, evitando possibili degenerazioni tra la presenza delle atmosfera planetaria e delle macchie. Il metodo è sviluppato per la spettroscopia di transito a bassa risoluzione ed è testato su simulazioni realistiche di future osservazioni di transiti planetari con Ariel, una missione spaziale dedicata all'osservazione di circa 1000 esopianeti in transito il cui lancio è previsto nel 2029. Successivamente, il metodo viene applicato alle osservazioni reali di HST di un pianeta in transito. Il capitolo 1 della tesi presenta la letteratura relativa al fenomeno. Il capitolo 2 presenta un metodo per correggere l'effetto delle macchie non attraversate dal pianeta in transito, partendo da un modello base dell'attività stellare, dove la stella macchiata è simulata come una combinazione lineare di spettri stellari a diverse temperature e la stella ha un'emissione uniforme. Il metodo è testato su 3 sistemi transitanti che saranno osservati dalla missione Ariel. Nel capitolo 3 è introdotto un altro componente nel modello di attività stellare, rendendolo più realistico. Infatti, sono simulati nuovamente gli stessi target analizzati nel Capitolo 2 ma includendo l'effetto di oscuramento al bordo. In questo capitolo è discussa l'importanza di tener conto di questo effetto se si vuole ottenere una buona stima dei parametri delle macchie e una buona correzione dell'atmosfera del pianeta. Nel Capitolo 4 l'approccio presentato nei capitoli precedenti, e testato su simulazioni, è applicato a osservazioni di transiti planetari del pianeta LHS 1140 b con il Telescopio Spaziale Hubble. L'analisi porta a due possibili scenari: nel primo la stella è molto attiva e quasi il 65% della sua superficie è ricoperta da macchie (contro altri indicatori in letteratura che suggeriscono una stella tranquilla); nel secondo, la stella è silenziosa ma è circa 300 K più fredda rispetto al primo scenario. In entrambi i casi, la modulazione cromatica osservata derivata dalle curve di luce del transito planetario non è dovuta alla presenza di un'atmosfera planetaria. Nel Capitolo 5, vengono analizzate le curve di luce TESS della stella attiva V1298 Tau, modellando la stella con un modello a 4 macchie rotanti sulla superficie stellare. Tale studio permette non solo di ricavare la distribuzione delle macchie su V1298 Tau ma anche di correggere le curve di luce di transito dei 4 pianeti orbitanti intorno alla stella per effetto delle macchie non occultate. I risultati mostrano che l'effetto delle macchie può produrre differenti profondità di transito per i 4 pianeti in banda TESS e K2, giustificando così la discrepanza tra i raggi planetari nelle due bande riportata nella letteratura scientifica.This thesis focuses on the quantification of the impact of stellar activity on observations of transiting planets and on the identification of a methodology to correct these effects. In particular, the role of starspots, both un-occulted and occulted is considered. The presence of spots on the visible stellar disk may distort the primary transit light curve in a wavelength-dependent way, mimicking the presence of an atmosphere. To take into account this bias, the thesis presents an innovative method to estimate the spots properties and their distribution from the out-of-transit observations and, on this basis, correct the planetary transit light curves, avoiding possible degeneracy between the presence of the planetary atmosphere and of the spots. The method is developed for low-resolution transit spectroscopy and is tested on realistic simulations of future observations of planetary transits with Ariel, a space mission dedicated to the observation of about 1000 transiting exoplanets whose launch is expected in 2029. Then, the method is applied to real observations of HST of a transiting planet. The first chapter of the thesis presents the state of the art of efforts done so far to mitigate the effect of the spots in planetary observations (chapter 1). Chapter 2 presents a method for correcting the effect of spots not-crossed by the transiting planet, starting from a basic model of the stellar activity, where the spotted star is simulated as a linear combination of stellar spectra at different temperatures and the star has a uniform emission. The method is tested on 3 simulated targets of transiting systems that will be observed by the Ariel mission. In Chapter 3, I introduced another component in the stellar model, making it more realistic. In fact, I simulate again the same targets analyzed in Chapter 2 but including the limb darkening effect to the stellar model. In this chapter, I show the importance of taking into account this effect if a good estimate of the spots’ parameters and a good correction of the planet's atmosphere have to be obtained. In Chapter 4 the approach presented in the previous chapters, and tested on simulations, is applied to observations of planetary transits of the planet LHS 1140 b, acquired with the Hubble Space Telescope. The analysis leads to two possible scenarios: in the first one the star is very active and almost the 65% of its surface is covered by spots (against other indicators in the literature suggesting a quiet star); in the second one, the star is quiet but is about 300 K cooler than in the first scenario. In both cases, the observed chromatic modulation derived from the planetary transit light curves is not due to the presence of a planetary atmosphere. In Chapter 5, I analyze the TESS light curves of the active star V1298 Tau, by modeling the star with a model dominated by 4 spots, co-rotating with the stellar surface. Such a study allows not only to derive the distribution of spots on V1298 Tau but also to correct the transit light curves of the 4 planets orbiting around the star for the effect of non-occulted spots. The results show that the spots’ effect may produce different transit depths for the 4 planets in the TESS and the K2 band, thus justifying the discrepancy between the planetary radii in the two bands reported in the scientific literature

Dissecting out the contribution of cognitive, social, and physical activities to environmental enrichment\u27s ability to protect Alzheimer\u27s mice against cognitive impairment

Retrospective studies suggest that lifestyle activities may provide protection against Alzheimer s Disease (AD). However, such studies can be inaccurate and prospective longitudinal studies investigating lifestyle protection against AD are both impractical and impossible to control for. Transgenic (Tg+) AD mice offer a model in a well controlled environment for testing the potential for environmental factors to impact AD development. In an initial study, Tg+ and non-transgenic (Tg-) mice were housed in either environmentally enriched (EE) or standard housing (SH) from 2-6 months of age, with a behavioral battery given during the last 5 weeks of housing. In the Morris maze, platform recognition, and radial arm water maze tasks, Tg+/EE mice were completely protected from cognitive impairment present in Tg+/SH mice and comparable to control Tg-/SH mice in cognitive performance. The current study utilized the same cognitive-based behavioral battery and multimetric statis statistical analysis to investigate the protective effects of complete environment enrichment (EE) versus several of its components (physical activity, social interactions) in AD transgenic mice. The AD transgenic mice utilized develop beta-amyloid (AB) deposition and cognitive impairment by 6-7 months of age. Similar to our initial study, results show that complete EE (physical, social, and cognitive activities) from 2 to 8 months of age completely protected AD transgenic mice from cognitive impairment in tasks representing different cognitive domains - working memory, reference learning, and search/recognition. In strong contrast, Tg+ mice reared in environments that included physical activity and social interaction, or only social interaction, were not protected from cognitive impairment in adulthood -- enhanced cognitive activity was required over and above that present in these other environments. Through use of discriminant function analysis, EE and/or NT mice were consistently discriminated from the poorer performing other housing groups. The cognitive benefits observed in EE-housed Tg+ mice occurred without significant changes in cortical AB levels, plasma cytokine levels, or plasma corticosterone levels, suggesting involvement of mechanisms independent of these endpoints. However, EE-housed Tg+ mice did have decreased dendritic length of neurons in the parietal cortex (but not hippocampus). Noteworthy is that plasma cytokine levels and hippocampal dendritic length consistently correlated with cognitive measures, suggesting their involvement in underlying mechanisms of cognitive performance. The present work provides the first evidence that complete EE (including enhanced cognitive activity) is needed to provide cognitive protection against AD in a Tg+ model of the disease, while the physical and social activity components of EE do not alone lead to protection. These results suggest that humans desiring to gain maximal environmental protection against AD should live a lifestyle high in cognitive, social, and physical activities together

Primary signet ring cell adenocarcinoma of the uterine cervix — A rare neoplasm that raises the question of metastasis to the cervix

AbstractPrimary signet ring cell adenocarcinoma is extremely rare. Signet ring cell carcinoma is more commonly primary in the stomach or breast, and the more likely metastatic disease to the cervix needs to be ruled out. We present a case of primary signet ring cell carcinoma of the cervix and review the literature

L’ESPERIENZA DELLA SICILIA QUALE REGIONE CAPOFILA NELLA INTRODUZIONE DELLA VACCINAZIONE UNIVERSALE CONTRO I ROTAVIRUS

La gastroenterite da rotavirus (GARV) rappresenta uno dei principali bisogni assistenziali durante l’età pediatrica. Purtroppo, in Italia, in assenza di notifica obbligatoria e di specifici sistemi di sorveglianza, le uniche valutazioni epidemiologiche disponibili sulle GARV sono rese possibili dall’analisi delle ospedalizzazioni. Il presente lavoro ha avuto l’obiettivo di valutare le ospedalizzazioni per GARV e per intussuscezione, avvenute in Sicilia in soggetti di età compresa tra 0 e 60 mesi, negli anni 2003-2012 (periodo prevaccinale) e 2013 (anno di introduzione della vaccinazione antirotavirus). Nel periodo in esame si sono osservate 9.886 ospedalizzazioni per GARV con una media annua di 899 casi. La maggior parte dei ricoveri (62,3%) è stata registrata nella fascia di età compresa tra 0 e 2 anni con una progressiva riduzione negli anni di vita successivi. Durante il 2013 si è osservata una copertura vaccinale regionale attestatasi tra il 30 ed il 40% per la prima dose ed il 25-35% per la seconda dose. Nello stesso anno si è assistito ad una riduzione dei casi di GARV di circa il 38,9% nei soggetti di età 0-5 anni (931 casi/anno nel 2003-2012 vs. 569 nel 2013) e superiore al 50% nella fascia di età 0-11 mesi (277 casi/anno nel 2003-2012 vs. 137 nel 2013). Diversamente, nel 2013 il numero di ospedalizzazioni per intussuscezione in soggetti di età compresa tra 0 ed 11 mesi si è mantenuta in linea con quanto osservato in epoca prevaccinale (15 casi nel 2013 vs. 15,4 casi/anno osservati in media tra 2003 e 2012). I dati presentati evidenziano l’importante peso assistenziale che le GARV hanno annualmente in Sicilia e supportano l’efficacia della vaccinazione nella riduzione significativa dei casi di ospedalizzazione per GARV in assenza di incrementi di rischio di intussuscezione

Paraneoplastic SIADH and Dermatomyositis in Cervical Cancer: A Case Report and Literature Review

We present the first known case of a patient with cervical squamous cell carcinoma complicated by paraneoplastic syndromes of both dermatomyositis and inappropriate secretion of antidiuretic hormone (SIADH). The patient in this case presented with generalized body pain and vaginal bleeding. Her cervical cancer was diagnosed as stage IIB by physical exam, imaging, and cervical biopsy, her dermatomyositis was confirmed by muscle and skin biopsy, and her SIADH was diagnosed based on laboratory findings

Quantitative estimation of nerve fiber engagement by vagus nerve stimulation using physiological markers

Background Cervical vagus nerve stimulation (VNS) is a rapidly emerging bioelectronic treatment for brain, metabolic, cardiovascular and immune disorders. Its desired and off-target effects are mediated by different nerve fiber populations and knowledge of their engagement could guide calibration and monitoring of VNS therapies. Objective /Hypothesis: Stimulus-evoked compound action potentials (eCAPs) directly provide fiber engagement information but are currently not feasible in humans. A method to estimate fiber engagement through common, noninvasive physiological readouts could be used instead of eCAP measurements. Methods In anesthetized rats, we recorded eCAPs while registering acute physiological response markers to VNS: cervical electromyography (EMG), changes in heart rate (ΔHR) and breathing interval (ΔBI). Quantitative models were established to capture the relationship between A-, B- and C-fiber type activation and those markers, and to quantitatively estimate fiber activation from physiological markers and stimulation parameters. Results In bivariate analyses, we found that EMG correlates with A-fiber, ΔHR with B-fiber and ΔBI with C-fiber activation, in agreement with known physiological functions of the vagus. We compiled multivariate models for quantitative estimation of fiber engagement from these markers and stimulation parameters. Finally, we compiled frequency gain models that allow estimation of fiber engagement at a wide range of VNS frequencies. Our models, after calibration in humans, could provide noninvasive estimation of fiber engagement in current and future therapeutic applications of VNS

Determinants of European parents' decision on the vaccination of their children against measles, mumps and rubella: A systematic review and meta-analysis

Low measles, mumps and rubella (MMR) immunization levels in European children highlight the importance of identifying determinants of parental vaccine uptake to implement policies for increasing vaccine compliance. The aim of this paper is to identify the main factors associated with partial and full MMR vaccination uptake in European parents, and combine the different studies to obtain overall quantitative measures. This activity is included within the ESCULAPIO project, funded by the Italian Ministry of Health. ORs and CIs were extracted, sources of heterogeneity explored and publication bias assessed. Forty-five papers were retrieved for the qualitative study, 26 of which were included in the meta-analysis. The following factors were associated with lower MMR vaccine uptake: misleading knowledge, beliefs and perceptions on vaccines (OR 0.57, CI 0.37-0.87); negative attitudes and behaviors toward vaccination (OR 0.71, CI 0.52-0.98); demographic characteristics, such as different ethnicity in Southern populations (OR 0.44, CI 0.31-0.61), higher child's age (OR 0.80, CI 0.76-0.85); low socio-economic status (OR 0.64, CI 0.51-0.80), especially low income (OR 0.39, CI 0.25-0.60) and education (OR 0.64, CI 0.48-0.84), high number of children (OR 0.54, CI 0.42-0.69), irregular marital status (OR 0.80, CI 0.66-0.96). The factors explaining heterogeneity were country location, administration modality, collection setting and responses reported on MMR alone or in combination. Findings from this study suggest policy makers to focus communication strategies on providing better knowledge, correct beliefs and perceptions on vaccines, and improving attitudes and behaviors in parents; and to target policies to people of ethnic minority from Southern Europe, low educated and deprived, with higher number of children and non-married marital status

Correcting Exoplanet Transmission Spectra for Stellar Activity with an Optimised Retrieval Framework

The chromatic contamination that arises from photospheric heterogeneities e.g. spots and faculae on the host star presents a significant noise source for exoplanet transmission spectra. If this contamination is not corrected for, it can introduce substantial bias in our analysis of the planetary atmosphere. We utilise two stellar models of differing complexity, StARPA and ASteRA, to explore the biases introduced by stellar contamination in retrieval under differing degrees of stellar activity. We use the retrieval framework TauREx3 and a grid of 27 synthetic, spot-contaminated transmission spectra to investigate potential biases and to determine how complex our stellar models must be in order to accurately extract the planetary parameters from transmission spectra. The input observation is generated using the more complex model (StARPA), in which the spot latitude is an additional, fixable parameter. This observation is then fed into a combined stellar-planetary retrieval which contains a simplified stellar model (ASteRA). Our results confirm that the inclusion of stellar activity parameters in retrieval minimises bias under all activity regimes considered. ASteRA performs very well under low to moderate activity conditions, retrieving the planetary parameters with a high degree of accuracy. For the most active cases, characterised by larger, higher temperature contrast spots, some minor residual bias remains due to ASteRA neglecting the interplay between the spot and the limb darkening effect. As a result of this, we find larger errors in retrieved planetary parameters for central spots (0 degrees) and those found close to the limb (60 degrees) than those at intermediate latitudes (30 degrees).Comment: 34 pages, 20 figures, accepted for publication in Ap

Epidemiology and clonality of carbapenem-resistant Acinetobacter baumannii from an intensive care unit in Palermo, Italy.

BACKGROUND: Multidrug-resistant Acinetobacter baumannii, initially considered as having a poor clinical relevance, is frequently isolated from infection cases in intensive care units. We describe the epidemiology of carbapenem resistant A. baumannii (CRAB) in a general ICU in Palermo, Italy, from October 2010 to March 2011. FINDINGS: 58 of 61 isolates exhibited MICs for meropenem or imipenem ≥16 mg/L. Forty-nine carried blaOXA-23 and two blaOXA-58 genes.Five subtype clusters were detected by rep-PCR. Clusters D and E included 10 isolates that tested negative for the carbapenem resistance genes. MLST attributed all isolates, but two, with sequence type (ST)2, whereas the two remaining isolates with ST78.The respiratory tract was the most common site of infection (26 out of 36 cases. 72.2%). A high infection related mortality rate was observed (18 out of 35 patients, 51.4%). Nineteen patients tested positive for other multidrug resistant organisms in addition to CRAB. In eight cases isolates belonging to distinct subtype clusters and/or with distinct carbapenemase profiles were identified. CONCLUSIONS: Carbapenem resistance was prominently driven by the dissemination of CRAB isolates belonging to ST2, carrying the carbapenemase gene blaOXA-23. The colonization/infection of some patients by multiple strains is suggestive of an endemic circulation of CRAB

Quantitative estimation of nerve fiber engagement by vagus nerve stimulation using physiological markers

© 2020 The Author(s) Background: Cervical vagus nerve stimulation (VNS) is an emerging bioelectronic treatment for brain, metabolic, cardiovascular and immune disorders. Its desired and off-target effects are mediated by different nerve fiber populations and knowledge of their engagement could guide calibration and monitoring of VNS therapies. Objective: Stimulus-evoked compound action potentials (eCAPs) directly provide fiber engagement information but are currently not feasible in humans. A method to estimate fiber engagement through common, noninvasive physiological readouts could be used in place of eCAP measurements. Methods: In anesthetized rats, we recorded eCAPs while registering acute physiological response markers to VNS: cervical electromyography (EMG), changes in heart rate (ΔHR) and breathing interval (ΔBI). Quantitative models were established to capture the relationship between A-, B- and C-fiber type activation and those markers, and to quantitatively estimate fiber activation from physiological markers and stimulation parameters. Results: In bivariate analyses, we found that EMG correlates with A-fiber, ΔHR with B-fiber and ΔBI with C-fiber activation, in agreement with known physiological functions of the vagus. We compiled multivariate models for quantitative estimation of fiber engagement from these markers and stimulation parameters. Finally, we compiled frequency gain models that allow estimation of fiber engagement at a wide range of VNS frequencies. Our models, after calibration in humans, could provide noninvasive estimation of fiber engagement in current and future therapeutic applications of VNS