Power Converters for Accelerators

Particle accelerators use a great variety of power converters for energizing their sub-systems; while the total number of power converters usually depends on the size of the accelerator or combination of accelerators (including the experimental setup), the characteristics of power converters depend on their loads and on the particle physics requirements: this paper aims to provide an overview of the magnet power converters in use in several facilities worldwide.Comment: 30 pages, contribution to the 2014 CAS - CERN Accelerator School: Power Converters, Baden, Switzerland, 7-14 May 201

Rectifiers

In particle accelerators, rectifiers are used to convert the AC voltage into DC or low-frequency AC to supply loads like magnets or klystrons. Some loads require high currents, others high voltages, and others both high current and high voltage. This presentation deals with the particular class of line commutated rectifiers (the switching techniques are treated elsewhere). The basic principles of rectification are presented. The effects of real world parameters are then taken into consideration. Some aspects related to the filtering of the harmonics both on the DC side and on the AC side are presented. Some protection issues associated with the use of thyristors and diodes are also treated. An example of power converter design, referring to a currently operating magnet power supply, is included. An extended bibliography (including some internet links) ends this presentation

Extreme Energy Cosmic Rays (EECR) Observation Capabilities of an "Airwatch from Space'' Mission

The longitudinal development and other characteristics of the EECR induced atmospheric showers can be studied from space by detecting the fluorescence light induced in the atmospheric nitrogen. According to the Airwatch concept a single fast detector can be used for measuring both intensity and time development of the streak of fluorescence light produced by the atmospheric shower induced by an EECR. In the present communication the detection capabilities for the EECR observation from space are discussed.Comment: 3 pages (LaTeX). To appear in the Proceedings of TAUP'9

Is fluorescein-guided technique able to help in resection of high-grade gliomas?

OBJECT: Fluorescein, a dye that is widely used as a fluorescent tracer, accumulates in cerebral areas where the blood-brain barrier is damaged. This quality makes it an ideal dye for the intraoperative visualization of high-grade gliomas (HGGs). The authors report their experience with a new fluorescein-guided technique for the resection of HGGs using a dedicated filter on the surgical microscope. METHODS: The authors initiated a prospective Phase II trial (FLUOGLIO) in September 2011 with the objective of evaluating the safety of fluorescein-guided surgery for HGGs and obtaining preliminary evidence regarding its efficacy for this purpose. To be eligible for participation in the study, a patient had to have suspected HGG amenable to complete resection of the contrast-enhancing area. The present report is based on the analysis of the short- and long-term results in 20 consecutive patients with HGGs (age range 45-74 years), enrolled in the study since September 2011. In all cases fluorescein (5-10 mg/kg) was injected intravenously after intubation. Tumor resection was performed with microsurgical technique and fluorescence visualization by means of BLUE 400 or YELLOW 560 filters on a Pentero microscope. RESULTS: The median preoperative tumor volume was 30.3 cm(3) (range 2.4-87.8 cm(3)). There were no adverse reactions related to fluorescein administration. Complete removal of contrast-enhanced tumor was achieved in 80% of the patients. The median duration of follow-up was 10 months. The 6-months progression-free survival rate was 71.4% and the median survival was 11 months. CONCLUSIONS: Analysis of these 20 cases suggested that fluorescein-guided technique with a dedicated filter on the surgical microscope is safe and allows a high rate of complete resection of contrast-enhanced tumor as determined on early postoperative MRI. Clinical trial registration no.: 2011-002527-18 (EudraCT)

Therapeutic immunization with HIV-1 Tat reduces immune activation and loss of regulatory T-cells and improves immune function in subjects on HAART.

Although HAART suppresses HIV replication, it is often unable to restore immune homeostasis. Consequently, non-AIDS-defining diseases are increasingly seen in treated individuals. This is attributed to persistent virus expression in reservoirs and to cell activation. Of note, in CD4(+) T cells and monocyte-macrophages of virologically-suppressed individuals, there is continued expression of multi-spliced transcripts encoding HIV regulatory proteins. Among them, Tat is essential for virus gene expression and replication, either in primary infection or for virus reactivation during HAART, when Tat is expressed, released extracellularly and exerts, on both the virus and the immune system, effects that contribute to disease maintenance. Here we report results of an ad hoc exploratory interim analysis (up to 48 weeks) on 87 virologically-suppressed HAART-treated individuals enrolled in a phase II randomized open-label multicentric clinical trial of therapeutic immunization with Tat (ISS T-002). Eighty-eight virologically-suppressed HAART-treated individuals, enrolled in a parallel prospective observational study at the same sites (ISS OBS T-002), served for intergroup comparison. Immunization with Tat was safe, induced durable immune responses, and modified the pattern of CD4(+) and CD8(+) cellular activation (CD38 and HLA-DR) together with reduction of biochemical activation markers and persistent increases of regulatory T cells. This was accompanied by a progressive increment of CD4(+) T cells and B cells with reduction of CD8(+) T cells and NK cells, which were independent from the type of antiretroviral regimen. Increase in central and effector memory and reduction in terminally-differentiated effector memory CD4(+) and CD8(+) T cells were accompanied by increases of CD4(+) and CD8(+) T cell responses against Env and recall antigens. Of note, more immune-compromised individuals experienced greater therapeutic effects. In contrast, these changes were opposite, absent or partial in the OBS population. These findings support the use of Tat immunization to intensify HAART efficacy and to restore immune homeostasis. TRIAL REGISTRATION: ClinicalTrials.gov NCT00751595

The Italian arm of the PREPARE study: an international project to evaluate and license a maternal vaccine against group B streptococcus.

BACKGROUND: Group B streptococcus (GBS) is a leading cause of sepsis, pneumonia and meningitis in infants, with long term neurodevelopmental sequelae. GBS may be associated with poor pregnancy outcomes, including spontaneous abortion, stillbirth and preterm birth. Intrapartum antibiotic prophylaxis (IAP) is currently the only way to prevent early-onset disease (presenting at 0 to 6 days of life), although it has no impact on the disease presenting over 6 days of life and its implementation is challenging in resource poor countries. A maternal vaccine against GBS could reduce all GBS manifestations as well as improve pregnancy outcomes, even in low-income countries. MAIN BODY: The term "PREPARE" designates an international project aimed at developing a maternal vaccination platform to test vaccines against neonatal GBS infections by maternal immunization. It is a non-profit, multi-center, interventional and experimental study (promoted by the St George University of London. [UK]) with the aim of developing a maternal vaccination platform, determining pregnancy outcomes, and defining the extent of GBS infections in children and mothers in Africa. PREPARE also aims to estimate the protective serocorrelates against the main GBS serotypes that cause diseases in Europe and Africa and to conduct two trials on candidate GBS vaccines. PREPARE consists of 6 work packages. In four European countries (Italy, UK, Netherlands, France) the recruitment of cases and controls will start in 2020 and will end in 2022. The Italian PREPARE network includes 41 centers. The Italian network aims to collect: GBS isolates from infants with invasive disease, maternal and neonatal sera (cases); cord sera and GBS strains from colonized mothers whose infants do not develop GBS infection (controls). SHORT CONCLUSION: PREPARE will contribute information on protective serocorrelates against the main GBS serotypes that cause diseases in Europe and Africa. The vaccine that will be tested by the PREPARE study could be an effective strategy to prevent GBS disease