Magnetohydrodynamic stability analysis of the pedestals of ASDEX Upgrade plasmas

openThe high confinement mode (H-mode) dramatically improves the confinement properties of present tokamak plasmas and is therefore the scenario envisioned for future fusion reactors. The main characteristic of this scenario is the formation of a pedestal, a zone of steep temperature and density gradients, at the edge of the plasma, by means of a transport barrier. The height of the pedestal is limited by the onset of edge localised modes (ELMs), quasi-periodic explosive instabilities at the plasma edge which expel particles and energy on millisecond time-scales. While ELMs in present day machines pose no danger, when scaled to a fusion reactor device they are predicted to cause significant damage to the machine components. As such, the understanding and exploitation of alternative regimes with high confinement, but without ELMs, is of significant interest. The onset of an ELM can be described by magnetohydrodynamic (MHD) stability codes. The aim and project of the current thesis carried out at Max-Planck-Institut für Plasmaphysik (IPP) in Garching (Germany), involves the automation of a workflow which runs codes to test the pedestal MHD stability, such as MISHKA, starting from a standardised set of experimental information. In addition, the HELENA code is employed as a high resolution equilibrium solver through the calculation of the Grad-Shafranov equation for a toroidal axisymmetric plasma. Once the workflow is implemented, it is applied to a database of experimental data from the ASDEX Upgrade tokamak to study the properties of the pedestal through stability diagrams. It is particularly important to provide an estimate of the distance to the MHD stability boundary in the various ELM-free regimes to understand how robust these regimes are and the margin a given regime has before a large ELM is triggered. Various deuterium and helium plasma discharges are studied in this regard.The high confinement mode (H-mode) dramatically improves the confinement properties of present tokamak plasmas and is therefore the scenario envisioned for future fusion reactors. The main characteristic of this scenario is the formation of a pedestal, a zone of steep temperature and density gradients, at the edge of the plasma, by means of a transport barrier. The height of the pedestal is limited by the onset of edge localised modes (ELMs), quasi-periodic explosive instabilities at the plasma edge which expel particles and energy on millisecond time-scales. While ELMs in present day machines pose no danger, when scaled to a fusion reactor device they are predicted to cause significant damage to the machine components. As such, the understanding and exploitation of alternative regimes with high confinement, but without ELMs, is of significant interest. The onset of an ELM can be described by magnetohydrodynamic (MHD) stability codes. The aim and project of the current thesis carried out at Max-Planck-Institut für Plasmaphysik (IPP) in Garching (Germany), involves the automation of a workflow which runs codes to test the pedestal MHD stability, such as MISHKA, starting from a standardised set of experimental information. In addition, the HELENA code is employed as a high resolution equilibrium solver through the calculation of the Grad-Shafranov equation for a toroidal axisymmetric plasma. Once the workflow is implemented, it is applied to a database of experimental data from the ASDEX Upgrade tokamak to study the properties of the pedestal through stability diagrams. It is particularly important to provide an estimate of the distance to the MHD stability boundary in the various ELM-free regimes to understand how robust these regimes are and the margin a given regime has before a large ELM is triggered. Various deuterium and helium plasma discharges are studied in this regard

Caratterizzazione dei parametri operativi dello strumento NISP della missione Euclid

Nel presente lavoro di tesi si introducono gli elementi descrittivi della missione spaziale Euclid e la strumentazione di bordo, in particolare ci si sofferma sul ciclo di osservazione e sulla descrizione dello strumento NISP. Si procede con l'analisi di dati di un test effettuato il 9-10 febbraio 2020. Il test fa parte di una campagna di test svolta nei mesi di gennaio e febbraio per validare lo strumento NISP prima della sua integrazione sul satellite. L'obiettivo è verificare che lo strumento esegua la sequenza di operazioni nelle tempistiche definite, assicurando così la riuscita della survey ed una corretta funzionalità dello strumento.ope

Serum Albumin Is Inversely Associated With Portal Vein Thrombosis in Cirrhosis

We analyzed whether serum albumin is independently associated with portal vein thrombosis (PVT) in liver cirrhosis (LC) and if a biologic plausibility exists. This study was divided into three parts. In part 1 (retrospective analysis), 753 consecutive patients with LC with ultrasound-detected PVT were retrospectively analyzed. In part 2, 112 patients with LC and 56 matched controls were entered in the cross-sectional study. In part 3, 5 patients with cirrhosis were entered in the in vivo study and 4 healthy subjects (HSs) were entered in the in vitro study to explore if albumin may affect platelet activation by modulating oxidative stress. In the 753 patients with LC, the prevalence of PVT was 16.7%; logistic analysis showed that only age (odds ratio [OR], 1.024; P = 0.012) and serum albumin (OR, -0.422; P = 0.0001) significantly predicted patients with PVT. Analyzing the 112 patients with LC and controls, soluble clusters of differentiation (CD)40-ligand (P = 0.0238), soluble Nox2-derived peptide (sNox2-dp; P < 0.0001), and urinary excretion of isoprostanes (P = 0.0078) were higher in patients with LC. In LC, albumin was correlated with sCD4OL (Spearman's rank correlation coefficient [r(s)], -0.33; P < 0.001), sNox2-dp (r(s), -0.57; P < 0.0001), and urinary excretion of isoprostanes (r(s), -0.48; P < 0.0001) levels. The in vivo study showed a progressive decrease in platelet aggregation, sNox2-dp, and urinary 8-iso prostaglandin F2 alpha-III formation 2 hours and 3 days after albumin infusion. Finally, platelet aggregation, sNox2-dp, and isoprostane formation significantly decreased in platelets from HSs incubated with scalar concentrations of albumin. Conclusion: Low serum albumin in LC is associated with PVT, suggesting that albumin could be a modulator of the hemostatic system through interference with mechanisms regulating platelet activation

Caratterizzazione dei parametri operativi dello strumento NISP della missione Euclid

Nel presente lavoro di tesi si introducono gli elementi descrittivi della missione spaziale Euclid e la strumentazione di bordo, in particolare ci si sofferma sul ciclo di osservazione e sulla descrizione dello strumento NISP. Si procede con l'analisi di dati di un test effettuato il 9-10 febbraio 2020. Il test fa parte di una campagna di test svolta nei mesi di gennaio e febbraio per validare lo strumento NISP prima della sua integrazione sul satellite. L'obiettivo è verificare che lo strumento esegua la sequenza di operazioni nelle tempistiche definite, assicurando così la riuscita della survey ed una corretta funzionalità dello strumento

Incidence and Recurrence of Portal Vein Thrombosis in Cirrhotic Patients

Cirrhosis has been long considered a risk factor for bleeding due to the co-existence of the so-called \u2018coagulopathy\u2019. More recently, however, compelling evidences have been provided on the occurrence of thrombotic events in the portal and systemic circulation.3\u20135 Portal vein thrombosis (PVT) is predominantly observed in patients with moderate to severe liver failure with a variable prevalence ranging from 0.6 to 25%. Only fewstudies have provided a longitudinal assessment of the PVT incidence and its sequelae, including recurrence and survival.9\u201314 Due to the variability of PVT incidence and the paucity of data regarding recurrence and survival,15\u201320 we prospectively analysed the incidence and the recurrence of PVT in the population of Portal vein thrombosis Relevance On Liver cirrhosis: ItalianVenous thromboticEventsRegistry (PROLIVER), a multi-centre study,8 which involved 43 enrolling centres in Italy (ClinicalTrials.gov Identifier: NCT01470547)

Emergency Department and Out-of-Hospital Emergency System (112-AREU 118) integrated response to Coronavirus Disease 2019 in a Northern Italy centre

Since December 2019, the world has been facing the life-threatening disease, named Coronavirus disease-19 (COVID-19), recognized as a pandemic by the World Health Organization. The response of the Emergency Medicine network, integrating "out-of-hospital" and "hospital" activation, is crucial whenever the health system has to face a medical emergency, being caused by natural or human-derived disasters as well as by a rapidly spreading epidemic outbreak. We here report the Pavia Emergency Medicine network response to the COVID-19 outbreak. The "out-of-hospital" response was analysed in terms of calls, rescues and missions, whereas the "hospital" response was detailed as number of admitted patients and subsequent hospitalisation or discharge. The data in the first 5 weeks of the Covid-19 outbreak (February 21-March 26, 2020) were compared with a reference time window referring to the previous 5 weeks (January 17-February 20, 2020) and with the corresponding historical average data from the previous 5 years (February 21-March 26). Since February 21, 2020, a sudden and sustained increase in the calls to the AREU 112 system was noted (+\u2009440%). After 5 weeks, the number of calls and missions was still higher as compared to both the reference pre-Covid-19 period (+\u200948% and\u2009+\u200910%, respectively) and the historical control (+\u200953% and\u2009+\u200922%, respectively). Owing to the overflow from the neighbouring hospitals, which rapidly became overwhelmed and had to temporarily close patient access, the population served by the Pavia system more than doubled (from 547.251 to 1.135.977 inhabitants,\u2009+\u2009108%). To minimize the possibility of intra-hospital spreading of the infection, a separate "Emergency Department-Infective Disease" was created, which evaluated 1241 patients with suspected infection (38% of total ED admissions). Out of these 1241 patients, 58.0% (n\u2009=\u2009720) were admitted in general wards (n\u2009=\u2009629) or intensive care unit (n\u2009=\u200991). To allow this massive number of admissions, the hospital reshaped many general ward Units, which became Covid-19 Units (up to 270 beds) and increased the intensive care unit beds from 32 to 60. In the setting of a long-standing continuing emergency like the present Covid-19 outbreak, the integration, interaction and team work of the "out-of-hospital" and "in-hospital" systems have a pivotal role. The present study reports how the rapid and coordinated reorganization of both might help in facing such a disaster. AREU-112 and the Emergency Department should be ready to finely tune their usual cooperation to respond to a sudden and overwhelming increase in the healthcare needs brought about by a pandemia like the current one. This lesson should shape and reinforce the future

Platelet Count Does Not Predict Bleeding in Cirrhotic Patients: Results from the PRO-LIVER Study.

OBJECTIVES: Thrombocytopenia is a hallmark for patients with cirrhosis and it is perceived as a risk factor for bleeding events. However, the relationship between platelet count and bleeding is still unclear. METHODS: We investigated the relationship between platelet count and major or clinical relevant nonmajor bleedings during a follow-up of ∼4 years. RESULTS: A total of 280 cirrhotic patients with different degrees of liver disease (67% males; age 64±37 years; 47% Child-Pugh B and C) were followed up for a median of 1,129 (interquartile range: 800-1,498) days yielding 953.12 patient-year of observation. The annual rate of any significant bleeding was 5.45%/year (3.57%/year and 1.89%/year for major and minor bleeding, respectively). Fifty-two (18.6%) patients experienced a major (n=34) or minor (n=18) bleeding event, predominantly from gastrointestinal origin. Platelet counts progressively decreased with the worsening of liver disease and were similar in patients with or without major or minor bleeding: a platelet count ≤50 × 103/μl was detected in 3 (6%) patients with and in 20 (9%) patients without any bleeding event. Conversely, prothrombin time-international normalized ratio was slightly higher in patients with overall or major bleeding. On Cox proportional hazard analysis, only a previous gastrointestinal bleeding (hazard ratio (HR): 1.96; 95% confidence interval: 1.11-3.47; P=0.020) and encephalopathy (HR: 2.05; 95% confidence interval: 1.16-3.62; P=0.013) independently predicted overall bleeding events. CONCLUSIONS: Platelet count does not predict unprovoked major or minor bleeding in cirrhotic patients

Platelet count does not predict bleeding in cirrhotic patients: Results from the PRO-LIVER Study

OBJECTIVES: Thrombocytopenia is a hallmark for patients with cirrhosis and it is perceived as a risk factor for bleeding events. However, the relationship between platelet count and bleeding is still unclear. METHODS: We investigated the relationship between platelet count and major or clinical relevant nonmajor bleedings during a follow-up of \ue2\u88\ubc4 years. RESULTS: A total of 280 cirrhotic patients with different degrees of liver disease (67% males; age 64\uc2\ub137 years; 47% Child\ue2\u80\u93Pugh B and C) were followed up for a median of 1,129 (interquartile range: 800\ue2\u80\u931,498) days yielding 953.12 patient-year of observation. The annual rate of any significant bleeding was 5.45%/year (3.57%/year and 1.89%/year for major and minor bleeding, respectively). Fifty-two (18.6%) patients experienced a major (n=34) or minor (n=18) bleeding event, predominantly from gastrointestinal origin. Platelet counts progressively decreased with the worsening of liver disease and were similar in patients with or without major or minor bleeding: a platelet count \ue2\u89\ua450\uc3\u97103/\uce\ubcl was detected in 3 (6%) patients with and in 20 (9%) patients without any bleeding event. Conversely, prothrombin time-international normalized ratio was slightly higher in patients with overall or major bleeding. On Cox proportional hazard analysis, only a previous gastrointestinal bleeding (hazard ratio (HR): 1.96; 95% confidence interval: 1.11\ue2\u80\u933.47; P=0.020) and encephalopathy (HR: 2.05; 95% confidence interval: 1.16\ue2\u80\u933.62; P=0.013) independently predicted overall bleeding events. CONCLUSIONS: Platelet count does not predict unprovoked major or minor bleeding in cirrhotic patients

Frequency of Left Ventricular Hypertrophy in Non-Valvular Atrial Fibrillation

Left ventricular hypertrophy (LVH) is significantly related to adverse clinical outcomes in patients at high risk of cardiovascular events. In patients with atrial fibrillation (AF), data on LVH, that is, prevalence and determinants, are inconsistent mainly because of different definitions and heterogeneity of study populations. We determined echocardiographic-based LVH prevalence and clinical factors independently associated with its development in a prospective cohort of patients with non-valvular (NV) AF. From the "Atrial Fibrillation Registry for Ankle-brachial Index Prevalence Assessment: Collaborative Italian Study" (ARAPACIS) population, 1,184 patients with NVAF (mean age 72 \ub1 11 years; 56% men) with complete data to define LVH were selected. ARAPACIS is a multicenter, observational, prospective, longitudinal on-going study designed to estimate prevalence of peripheral artery disease in patients with NVAF. We found a high prevalence of LVH (52%) in patients with NVAF. Compared to those without LVH, patients with AF with LVH were older and had a higher prevalence of hypertension, diabetes, and previous myocardial infarction (MI). A higher prevalence of ankle-brachial index 640.90 was seen in patients with LVH (22 vs 17%, p = 0.0392). Patients with LVH were at significantly higher thromboembolic risk, with CHA2DS2-VASc 652 seen in 93% of LVH and in 73% of patients without LVH (p <0.05). Women with LVH had a higher prevalence of concentric hypertrophy than men (46% vs 29%, p = 0.0003). Logistic regression analysis demonstrated that female gender (odds ratio [OR] 2.80, p <0.0001), age (OR 1.03 per year, p <0.001), hypertension (OR 2.30, p <0.001), diabetes (OR 1.62, p = 0.004), and previous MI (OR 1.96, p = 0.001) were independently associated with LVH. In conclusion, patients with NVAF have a high prevalence of LVH, which is related to female gender, older age, hypertension, and previous MI. These patients are at high thromboembolic risk and deserve a holistic approach to cardiovascular prevention