2,049 research outputs found

    Beam Dynamics Characterization of the IFMIF/EVEDA RFQ Input Beam

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    The high intensity accelerators are one of the world-wide leading edge research in the beam dynamics studies. The upgrades of the existing accelerator LINAC4, FERMILAB, FAIR and the new applications on the neutron technologies such as ESS, IFMIF, MUNES, both for science research, medical treatment and material testing require an increase knowledge in the high intensity beams treatment. One of the most difficult part to be treated and which represent the first obstacle in increasing the beam intensity in the accelerators, is the injector part: the large number of charge particles at low energy forms a strongly interacting system, subjected to the Coulombian interaction. The situation further complicates due to the presence of different species which produces a plasma-like behavior of the beam. On the behalf of the INFN-LNL team, I participated to the commissioning of the high intensity injector (source and low energy transfer line) of the IFMIF/EVEDA project. Via experiments and simulation model developments I contributed to the study of the beam behavior in this specific framework. In particular I upgrade the emittance measurement routine in order to manage correctly the artifacts; I develop and benchmark with measurements self-consistent simulation models of the LEBT and extraction transfer line, which includes the secondary electron from residual gas and from metal due to collisions; I design a modification of medium and high energy line in order to test the CW steady state of the longest radio frequency quadrupole in the world, an in-kind contribution of INFN. All the development routines and experience will give important contributions for the next high intensity facilities. The first chapter presents the motivation of the IFMIF project and the main characteristics required by the accelerator. The main challenges of such accelerator are also listed. The second chapter introduces the main concepts of the beam dynamics of space-charge which will be used in the thesis. The third chapter presents the IFMIF/EVEDA project, with a description of the main elements; particular focus is made onto the source, the low energy beam transfer line and on the radio frequency quadrupole. Scaling law derivation for the extracted beam with contaminants is shown. The commissioning phases are introduced, each with its specific challenges. The fourth chapter presents the modification of the emittance analysis routine which can manage the ghost infested signal of the IFMIF/EVEDA emittancemeter. The fifth and the sixth chapters contains the simulation models developed to estimate the space-charge beam behavior under neutralization regime: the model with constant neutralization and the one with the full secondary plasma evolution are presented and benchmarked with the measurements. In the fifth chapter the measurements refers to 60−55 mA proton beam at 50 keV, while for the sixth chapter the beam considered is composed of 140−135 mA deuteron beam at 100 keV. In these chapters, the variation of the radio frequency quadrupole beam input characteristics with respect to the electromagnetic plasma confinement of the low energy transfer line is studied. The original contribution in these simulations is given by the emitted secondary electron from metal, which as some effects on the space charge compensation process, on the emittance value. Deep study of the multispecies distributions and behavior was performed. The four chapter defines, for the experimental proton point considered, the solenoid variations where searching the maximum radio frequency quadrupole transmission. The output beam behavior of this one is studied in commissioning perspective. In thesixth chapter, after testing the radio frequency quadrupole transmission with the secondary plasma model (also said dynamic neutralization model) with a realistic beam distribution, the simulations of the extraction system are presented. The benchmark with the measurements are also performed. The seventh chapter presents the design of the modification of the medium and high energy transfer sections of the accelerator in order to allow the test of the CW of the radio frequency quadrupole, bypassing the superconductive cavities. Extensive simulations of the system robustness to the errors are explored. The last chapter reports the conclusions

    Status of the RFQ linac installation and conditioning of the Linear IFMIF Prototype Accelerator

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    Abstract The Radio Frequency Quadrupole (RFQ) linac and 1.6 MW RF power system of the Linear IFMIF Prototype Accelerator (LIPAc) facility in the International Fusion Energy Research Center (IFERC) in Rokkasho (Japan) has been installed and conditioned. During the assembly and tuning process, the RFQ cavity was protected with a temporary tent from the potential deterioration of performance caused by dust. The vacuum in the cavity was improved through the 100 °C baking process of the cavity. The high power test of the 175 MHz RF systems up to 200 kW in CW for each of the eight RF chains was performed for checking its stable output reproducibility in Japan, before connecting 9–3/16 inch coaxial transmission lines from the RF chains to the RF input couplers of the cavity. It was confirmed that the eight RF chains provided the balanced RF power to the single RFQ cavity in-phase using a feedback loop and a synchronization system. The peak power in the cavity achieved 150 kW in the pulsed mode, which corresponds approximately to the required electric field to accelerate proton beam. Such RF conditioning process is ongoing to achieve 600 kW approximately required for deuteron beam commissioning planned in 2018

    Commissioning Plan of the IFMIF-DONES Accelerator

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    IFMIF-DONES (International Fusion Materials Irradiation Facility- DEMO-Oriented Neutron Early Source) - a powerful neutron irradiation facility for studies and certification of materials to be used in fusion reactors - is planned as part of the European roadmap to fusion electricity. Its main goal will be to characterize and to qualify materials under irradiation in a neutron field similar to the one faced in a fusion reactor. The intense neutron source is produced by impinging deuterons, from high-power linear deuteron accelerator, on a liquid lithium curtain. The facility has accomplished the preliminary design phase and is currently in its detailed design phase. At the present stage, it is important to have a clear understanding of how the commissioning of the facility will be performed, especially the commissioning of a 5 MW CW deuteron beam, together with the lithium curtain and the beam optimization for the neutron irradiation. In this contribution, the present plans for the hardware and beam commissioning of the accelerator will be given, focusing on the most critical aspects of the tiered approach and on the integration of the procedure with the lithium and tests systems

    Effect of Lactoferrin on Clinical Outcomes of Hospitalized Patients with COVID-19: The LAC Randomized Clinical Trial

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    : As lactoferrin is a nutritional supplement with proven antiviral and immunomodulatory abilities, it may be used to improve the clinical course of COVID-19. The clinical efficacy and safety of bovine lactoferrin were evaluated in the LAC randomized double-blind placebo-controlled trial. A total of 218 hospitalized adult patients with moderate-to-severe COVID-19 were randomized to receive 800 mg/die oral bovine lactoferrin (n = 113) or placebo (n = 105), both given in combination with standard COVID-19 therapy. No differences in lactoferrin vs. placebo were observed in the primary outcomes: the proportion of death or intensive care unit admission (risk ratio of 1.06 (95% CI 0.63-1.79)) or proportion of discharge or National Early Warning Score 2 (NEWS2) ≤ 2 within 14 days from enrollment (RR of 0.85 (95% CI 0.70-1.04)). Lactoferrin showed an excellent safety and tolerability profile. Even though bovine lactoferrin is safe and tolerable, our results do not support its use in hospitalized patients with moderate-to-severe COVID-19

    Fatality rate and predictors of mortality in an Italian cohort of hospitalized COVID-19 patients

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    Clinical features and natural history of coronavirus disease 2019 (COVID-19) differ widely among different countries and during different phases of the pandemia. Here, we aimed to evaluate the case fatality rate (CFR) and to identify predictors of mortality in a cohort of COVID-19 patients admitted to three hospitals of Northern Italy between March 1 and April 28, 2020. All these patients had a confirmed diagnosis of SARS-CoV-2 infection by molecular methods. During the study period 504/1697 patients died; thus, overall CFR was 29.7%. We looked for predictors of mortality in a subgroup of 486 patients (239 males, 59%; median age 71 years) for whom sufficient clinical data were available at data cut-off. Among the demographic and clinical variables considered, age, a diagnosis of cancer, obesity and current smoking independently predicted mortality. When laboratory data were added to the model in a further subgroup of patients, age, the diagnosis of cancer, and the baseline PaO2/FiO2 ratio were identified as independent predictors of mortality. In conclusion, the CFR of hospitalized patients in Northern Italy during the ascending phase of the COVID-19 pandemic approached 30%. The identification of mortality predictors might contribute to better stratification of individual patient risk

    Beta-Blocker Use in Older Hospitalized Patients Affected by Heart Failure and Chronic Obstructive Pulmonary Disease: An Italian Survey From the REPOSI Register

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    Beta (β)-blockers (BB) are useful in reducing morbidity and mortality in patients with heart failure (HF) and concomitant chronic obstructive pulmonary disease (COPD). Nevertheless, the use of BBs could induce bronchoconstriction due to β2-blockade. For this reason, both the ESC and GOLD guidelines strongly suggest the use of selective β1-BB in patients with HF and COPD. However, low adherence to guidelines was observed in multiple clinical settings. The aim of the study was to investigate the BBs use in older patients affected by HF and COPD, recorded in the REPOSI register. Of 942 patients affected by HF, 47.1% were treated with BBs. The use of BBs was significantly lower in patients with HF and COPD than in patients affected by HF alone, both at admission and at discharge (admission, 36.9% vs. 51.3%; discharge, 38.0% vs. 51.7%). In addition, no further BB users were found at discharge. The probability to being treated with a BB was significantly lower in patients with HF also affected by COPD (adj. OR, 95% CI: 0.50, 0.37-0.67), while the diagnosis of COPD was not associated with the choice of selective β1-BB (adj. OR, 95% CI: 1.33, 0.76-2.34). Despite clear recommendations by clinical guidelines, a significant underuse of BBs was also observed after hospital discharge. In COPD affected patients, physicians unreasonably reject BBs use, rather than choosing a β1-BB. The expected improvement of the BB prescriptions after hospitalization was not observed. A multidisciplinary approach among hospital physicians, general practitioners, and pharmacologists should be carried out for better drug management and adherence to guideline recommendations

    Clinical features and outcomes of elderly hospitalised patients with chronic obstructive pulmonary disease, heart failure or both

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    Background and objective: Chronic obstructive pulmonary disease (COPD) and heart failure (HF) mutually increase the risk of being present in the same patient, especially if older. Whether or not this coexistence may be associated with a worse prognosis is debated. Therefore, employing data derived from the REPOSI register, we evaluated the clinical features and outcomes in a population of elderly patients admitted to internal medicine wards and having COPD, HF or COPD + HF. Methods: We measured socio-demographic and anthropometric characteristics, severity and prevalence of comorbidities, clinical and laboratory features during hospitalization, mood disorders, functional independence, drug prescriptions and discharge destination. The primary study outcome was the risk of death. Results: We considered 2,343 elderly hospitalized patients (median age 81 years), of whom 1,154 (49%) had COPD, 813 (35%) HF, and 376 (16%) COPD + HF. Patients with COPD + HF had different characteristics than those with COPD or HF, such as a higher prevalence of previous hospitalizations, comorbidities (especially chronic kidney disease), higher respiratory rate at admission and number of prescribed drugs. Patients with COPD + HF (hazard ratio HR 1.74, 95% confidence intervals CI 1.16-2.61) and patients with dementia (HR 1.75, 95% CI 1.06-2.90) had a higher risk of death at one year. The Kaplan-Meier curves showed a higher mortality risk in the group of patients with COPD + HF for all causes (p = 0.010), respiratory causes (p = 0.006), cardiovascular causes (p = 0.046) and respiratory plus cardiovascular causes (p = 0.009). Conclusion: In this real-life cohort of hospitalized elderly patients, the coexistence of COPD and HF significantly worsened prognosis at one year. This finding may help to better define the care needs of this population

    Antidiabetic Drug Prescription Pattern in Hospitalized Older Patients with Diabetes

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    Objective: To describe the prescription pattern of antidiabetic and cardiovascular drugs in a cohort of hospitalized older patients with diabetes. Methods: Patients with diabetes aged 65 years or older hospitalized in internal medicine and/or geriatric wards throughout Italy and enrolled in the REPOSI (REgistro POliterapuie SIMI—Società Italiana di Medicina Interna) registry from 2010 to 2019 and discharged alive were included. Results: Among 1703 patients with diabetes, 1433 (84.2%) were on treatment with at least one antidiabetic drug at hospital admission, mainly prescribed as monotherapy with insulin (28.3%) or metformin (19.2%). The proportion of treated patients decreased at discharge (N = 1309, 76.9%), with a significant reduction over time. Among those prescribed, the proportion of those with insulin alone increased over time (p = 0.0066), while the proportion of those prescribed sulfonylureas decreased (p < 0.0001). Among patients receiving antidiabetic therapy at discharge, 1063 (81.2%) were also prescribed cardiovascular drugs, mainly with an antihypertensive drug alone or in combination (N = 777, 73.1%). Conclusion: The management of older patients with diabetes in a hospital setting is often sub-optimal, as shown by the increasing trend in insulin at discharge, even if an overall improvement has been highlighted by the prevalent decrease in sulfonylureas prescription
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