Conceptual design of a GEM (gas electron multiplier) based gas Cherenkov detector for measurement of 17 MeV gamma rays from T(D, γ)5He in magnetic confinement fusion plasmas.

The only method for assessing the fusion power throughput of a deuterium-tritium (DT) reactor presently relies on determining the absolute number of 14 MeV neutrons produced in the DT plasma. An independent method, developed and investigated during the recent DT campaign at the Joint European Torus, is based on the absolute counting of 17 MeV gamma rays produced by the competing T(D, γ)5He reaction that features a very weak branching ratio (about 3-6 × 10-6) when compared to the main T(D, n)4He reaction. The state-of-the-art spectrometer used for gamma-ray measurements in magnetic confinement fusion plasmas is LaBr3(Ce) scintillator detectors, although they require significant neutron shielding to extract a relatively weak gamma-ray signal from a much more abundant neutron field. A better approach relies on a gamma-ray detector that is intrinsically insensitive to neutrons. We have advanced the design of a gamma-ray counter based on the Cherenkov effect for gamma-rays whose energy exceeds 11 MeV, optimized to work in the neutron-rich environment of a steady-state, magnetically confined fusion plasma device. The gamma-rays interact with an aluminum window and extract electrons that move into the radiator emitting photons via the Cherenkov effect. Since the Cherenkov light consists of few photons (25 on average) in the far UV band (100-200 nm), a pre-amplifier is required to transport the photons to the neutron-shielded location, which may be a few meters away, where the readout elements of the detector, either a silicon or standard photomultiplier tube, are placed. The present work focuses on the development of a scintillating GEM (Gas Electron Multiplier) based pre-amplifier that acts as a Cherenkov photon pre-amplifier and wavelength shifter. This paper presents the result of a set of Garfield++ simulations developed to find the optimal GEM working parameters. A photon gain of 100 is obtained by biasing a single GEM foil to 1 kV.

A high-resolution neutron spectroscopic camera for the SPARC tokamak based on the Jet European Torus deuterium-tritium experience.

Dedicated nuclear diagnostics have been designed, developed, and built within EUROFUSION enhancement programs in the last ten years for installation at the Joint European Torus and capable of operation in high power Deuterium-Tritium (DT) plasmas. The recent DT Experiment campaign, called DTE2, has been successfully carried out in the second half of 2021 and provides a unique opportunity to evaluate the performance of the new nuclear diagnostics and for an understanding of their behavior in the record high 14 MeV neutron yields (up to 4.7 × 1018 n/s) and total number of neutrons (up to 2 × 1019 n) achieved on a tokamak. In this work, we will focus on the 14 MeV high resolution neutron spectrometers based on artificial diamonds which, for the first time, have extensively been used to measure 14 MeV DT neutron spectra with unprecedented energy resolution (Full Width at Half Maximum of ≈1% at 14 MeV). The work will describe their long-term stability and operation over the DTE2 campaign as well as their performance as neutron spectrometers in terms of achieved energy resolution and high rate capability. This important experience will be used to outline the concept of a spectroscopic neutron camera for the SPARC tokamak. The proposed neutron camera will be the first one to feature the dual capability to measure (i) the 2.5 and 14 MeV neutron emissivity profile via the conventional neutron detectors based on liquid or plastics scintillators and (ii) the 14 MeV neutron spectral emission via the use of high-resolution diamond-based spectrometers. The new opportunities opened by the spectroscopic neutron camera to measure plasma parameters will be discussed.

Role of neutron attenuators for gamma-ray measurements in deuterium-tritium magnetic confinement plasmas.

The Joint European Torus (JET) is the only tokamak in the world able to operate in Deuterium-Tritium (DT) plasmas. A successful DT experimental campaign, the DTE2, has recently been carried out, providing unique opportunities for studying both physics and technological aspects. In particular, it allowed us to investigate and benchmark the solutions adopted to attenuate the significant 14 MeV neutron flux, needed to enable high-resolution gamma-ray spectroscopy measurements on a tokamak. While in inertial confinement experiments, gamma-rays and neutrons are discriminated through time-of-flight techniques; in magnetic confinement experiments, the neutron attenuators are a key element to allow gamma-ray measurements in order to reestablish the 1 × 105 to 1 background to signal ratio. In this paper, the role of the reference neutron attenuators at JET, based on LiH, has been analyzed and described.

A new dedicated signal processing system for gamma-ray spectrometers in high power deuterium-tritium plasma scenarios in tokamaks.

The most performant deuterium-tritium (DT) plasma discharges realized by the Joint European Torus (JET) tokamak in the recent DT campaign have produced neutron yields on the order of 1018 n/s. At such high neutron yields, gamma-ray spectroscopy measurements with scintillators are challenging as events from the neutron-induced background often dominate over the signal, leading to a significant fraction of pileup events and instability of the photodetector gain along with the consequent degradation of the reconstructed spectrum. Here, we describe the solutions adopted for the tangential lanthanum bromide spectrometer installed at JET. A data acquisition system with free streaming mode digitization capabilities for the entire duration of the discharge has been used to solve dead-time related issues and a data reconstruction code with pileup recovery and photodetector gain drift restoration has been implemented for off-line analysis of the data. This work focuses on the acquired data storage and parsing, with a detailed explanation of the pileup recovery and gain drift restoration algorithms.

Fusion product measurements by nuclear diagnostics in the Joint European Torus deuterium-tritium 2 campaign (invited).

A new deuterium-tritium experimental, DTE2, campaign has been conducted at the Joint European Torus (JET) between August 2021 and late December 2021. Motivated by significant enhancements in the past decade at JET, such as the ITER-like wall and enhanced auxiliary heating power, the campaign achieved a new fusion energy world record and performed a broad range of fundamental experiments to inform ITER physics scenarios and operations. New capabilities in the area of fusion product measurements by nuclear diagnostics were available as a result of a decade long enhancement program. These have been tested for the first time in DTE2 and a concise overview is provided here. Confined alpha particle measurements by gamma-ray spectroscopy were successfully demonstrated, albeit with limitations at neutron rates higher than some 1017 n/s. High resolution neutron spectroscopy measurements with the magnetic proton recoil instrument were complemented by novel data from a set of synthetic diamond detectors, which enabled studies of the supra-thermal contributions to the neutron emission. In the area of escaping fast ion diagnostics, a lost fast ion detector and a set of Faraday cups made it possible to determine information on the velocity space and poloidal distribution of the lost alpha particles for the first time. This extensive set of data provides unique information for fundamental physics studies and validation of the numerical models, which are key to inform the physics and scenarios of ITER.

A new tangential gamma-ray spectrometer for fast ion measurements in deuterium and deuterium-tritium plasmas of the Joint European Torus.

A new tangential gamma-ray spectrometer has been developed for fast ion measurements in deuterium and deuterium-tritium plasmas of the Joint European Torus (JET). The instrument is based on a LaBr3 crystal with a photo-multiplier tube and replaces a pre-existing bismuth germanate detector, providing enhanced energy resolution and a counting rate capability in the MHz range. The line of sight is equipped with a LiH attenuator, which reduces the background due to 14 MeV neutron interactions with the crystal by more than two orders of magnitude and enables the observation of gamma-ray emission from confined α particles in JET deuterium-tritium plasmas. Thanks to its tangential line of sight, the detector can distinguish co- and counter-passing ions. The performance of the instrument is demonstrated through the results of recent JET fast ion experiments in deuterium plasmas.

First spatially resolved measurements of the D-3He α-particle source with the upgraded JET gamma-ray camera.

The Joint European Torus (JET) gamma-ray camera has been recently upgraded with the installation of new gamma-ray detectors, based on LaBr3(Ce) scintillation crystals, which add spectroscopic capability to the existing system allowing measurements with good energy resolution (5% at 0.622 MeV), a dynamic range from hundreds of keV up to about 30 MeV, and high counting rate capabilities of MCps. First gamma-ray measurements during the C38 campaign of the JET have been successfully carried out, in particular, in D-3He plasmas from three-ion ion cyclotron resonance heating experiments, where the detection of 16.4 MeV γ-rays from D + 3He → γ + 5Li reactions with the gamma-ray camera upgrade allowed determining the spatial profile of alpha particles born in D + 3He fusion reactions.

Thunderstorm asthma: a critical appraisal based on clinical practice

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Immunological treatments for occupational allergy.

Although avoidance of occupational triggers remains the primary step in the management of work-related allergies, immunological treatments (including biological agents and specific immunotherapy) can be regarded as potential therapeutic options for IgE-mediated diseases; for example, many studies with allergen-specific immunotherapy have been carried out on latex allergy, showing overall favorable results, at least with sublingual immunotherapy. On the other hand, only few case reports have suggested the efficacy of immunotherapy in baker's asthma as well as in laboratory animal-induced asthma. The new technologies, including component-resolved diagnosis and recombinant allergens, are expected to improve the quality and efficacy of specific immunotherapy in the future. Also the use of omalizumab may represent a suitable therapeutic choice in very selected cases of occupational allergy, as well as an approach to reduce side effects of venom immunotherapy in subjects with previous severe reactions to the treatment.

Occupational diseases due to allergic and toxic chemicals in health care workers: fitness for work.

The purpose of this review is to suggest job fitness criteria for health care workers exposed to sensitizing or chemical agents. These recommendations are derived from a comparison between previous documents on prevention and management of allergic and chemical risks in health care settings and updated evidence; the job fitness criteria and the main documents on these topics are summarized in tables. Glove allergy, in particular latex allergy, is still a significant problem but we should remember that a wide choice of alternative materials is now easily available; many different alternative health products are also currently available when an allergy to disinfectants or detergents is diagnosed. Hence the prevention of allergic diseases is mostly based on an appropriate choice and use of the gloves and health products according to the specific tasks and possible individual susceptibility; this meets the requirements of the "good health care organization", which translates into lower costs, if possible, as well as the best protection of worker's health. Concerning chemical risk, it should be remembered that during the last 20 years the improvements made in work environments have profoundly changed the mode and the levels of exposure to chemical substances and the current recommendations concerning the management of workers exposed to anesthetic gases, antineoplastic agents and sterilizers/disinfectants significantly differ from those of early 1990s. However, the past prudential guidelines are still valid for formaldehyde.

[Consensus Document. Update on latex exposure and use of gloves in Italian health care settings]. / Documento di Consenso. Aggiornamenti in tema di esposizione a latice e impiego di guanti in ambito sanitario.

This consensus document was prepared by an Italian working group including occupational health professionals involved for many years in the management of glove- and latex-related problems in health care settings. The aim of this document was to address the most significant technical, epidemiological, clinical, environmental and prevention problems related to the use of gloves and latex. The group's recommendations are based on scientific evidence and practical experience but they cannot be considered as final. These topics need to be periodically revised. The following points should be taken into account: glove quality seems to have improved considerably but the information on glove features provided by the manufacturers is often still inaccurate or incomplete; the regulations in force provide that the manufacturers perform tests to supply evidence for the quality of the products but they do not indicate which analytical method should be used and they do not require that the results be reported in the technical data sheets. Thus the manufacturers have only to declare that their products are "in accordance with the rules"; therefore, purchasers should require the manufacturing companies to supply detailed information and verify their reliability. Moreover, the rules should be adapted to higher quality standards; occupational physicians must be involved for the correct choice and purchase of protective gloves; the use of gloves (in particular latex gloves) and latex devices in health care settings should be based on specific criteria: procedures must be available stating which kind of gloves are suitable for specific tasks. When exposure to latex cannot be avoided it is necessary to choose products that have good biocompatibility (e.g., powder free-gloves with low allergen content); once and for all latex powdered gloves should no longer be commercially available! labels for latex devices (including gloves) should report the extractable latex allergen content. Limit values for extractable latex allergens should be established; the use of synthetic rubber gloves should be encouraged since some materials (e.g., neoprene and nitrile rubber) appear to have physical properties and protective efficacy similar to latex, plus good biocompatibility; more studies should be promoted to verify the protective efficacy of new synthetic materials; health care workers should be informed about the advisability and usefulness of using materials other than latex; health care services should not cause additional risks but rather highlight the advantages for workers and patients if the use of latex gloves and devices is minimized.

How to prevent immunological reactions in leprosy patients and interrupt transmission of Mycobacterium leprae to healthy subjects: two hypotheses.

The basis of World Health Organization strategy for leprosy elimination is that the only source and reservoir for infection are patients with the disease. It was assumed that multi drug therapy (MDT) would reduce transmission of Mycobacterium leprae, but there is no convincing evidence for this. Furthermore, even if MDT has been proved to be extremely effective against the infectious disease, a noticeable proportion of leprosy patients can suffer from immunologic hypersensitivity reactions which are now the most significant issue in the managements of the disease. In endemic areas it was found that: M. leprae survives outside human body; healthy individuals harbor M. leprae bacilli in nasal cavity and shed micro-organisms in environment; there is widespread subclinical transmission of M. leprae with transient infection of the nose resulting in the development of a mucosal immune response. This disparate clinical, epidemiologic, and microbiologic evidence leads to the first hypothesis: that antigenic load in local tissues, sufficient to trigger the immune response, comes from external supply of M. leprae organisms. The hypothiocyanite anion (OSCN-) is generated in vivo by the reaction of thiocyanate with hydrogen peroxide catalyzed by lactoperoxidase. OSCN- is an antimicrobial oxidizing agent that prevents growth of bacteria, fungi, and viruses. OSNC- exists in lower airway secretions and lung has never been reported to be affected by leprosy. There is a sufficient concentration of OSCN- in the saliva, and accordingly mouth is rarely affected by leprosy. By contrast, the concentration of this compound is low or nil in nasal and lacrimal secretions and leprosy very often affects nose and eyes. The second hypothesis is that OSCN- may also protect from leprosy. Recently a method of OSCN- production, not involving enzymatic steps or use of toxic heavy-metal salts, has been patented. Studies on the susceptibility of M. leprae to hypothiocyanite could be carried out and, in case of positive results, the substance might be used in order to sterilize the nasal cavity of healthy carriers and prevent transmission of M. leprae to healthy subjects and to leprosy patients in whom it may trigger an immune response.

[Natural latex allergy. Patient management: from clinic to prevention. A review]. / Allergia a latice naturale. Gestione del paziente: dalla clinica alla prevenzione. Rassegna critica.

The widespread use of latex devices has been followed, in the last 25 years, by an increase in IgE mediated sensitization. The clinical manifestations of latex allergy affect the skin (urticaria and angioneurotic oedema), the lower and the upper respiratory tracts (rhinoconjunctivitis, asthma and glottis oedema), and the cardiovascular system (anaphylaxis). There is also an anaphylactic risk during surgery and invasive diagnostic procedures. Vegetable food cross-reacts with latex so that more than half of the patients show specific IgE against some food. Further than traditional groups at risk, as health care workers, other work categories have to be protected, because of the inappropriate use of latex gloves (food or drug industry workers, mechanics, panel beaters and so on). Recently the latex most important allergenic fractions have been characterized and recombinant allergens are now available. The recombinant allergens allow a better standardization of the extracts for diagnostic use, the production of safer extracts for immunotherapy as well as a more accurate evaluation of food cross-reactions. The recombinant allergens will allow a more accurate dosage of latex concentrations in air and in objects and, in future, to establish threshold limit values. The main aims of prevention are the replacement of latex with alternative elastomers, the reduction of work and extra work exposure and an efficient health survey in working environment. The use of latex gloves and devices among general population has to be discouraged. Specific immunotherapy has to be considered a second choice and restricted to highly qualified workers in order to realize a rehabilitation to their previous jobs. The actually obtained protection must be verified.

[Latex allergy. Preventive measures in health care workers: a comparison of Italian experiences]. / Allergia a latice. Approcci preventivi nelle Aziende Sanitarie: esperienze italiane a confronto. Risultati preliminari di un'indagine trasversale.

BACKGROUND: We have performed a transversal study in different Italian Regions to underline the problem related to natural latex allergy. OBJECTIVES: The aim of the study was to determine the glove use on the basis of the materials gloves were made of, to identify the departments and the qualifications mainly interested in the latex allergy problem, to check the required features for gloves and other rubber devices at the moment of the purchase, as well as the presence of guidelines, of training and information activities for health care workers and procedures for sensitized patients. METHODS: We sent a questionnaire to the local public Health Authorities (HA) in different Italian Regions. RESULTS: Number and regional distribution of the answers received back did not have statistical significance. Anyway, from the elaboration of the data it has been possible to obtain some interesting observations on both a theoretical and an operational level. The results showed: a) the level of interest and attention to the latex allergy problem has increased a lot recently; b) there is a high use of latex gloves (>50% of HA), in particular in surgical and intensive care departments; c) there are differences on an operational level between HA, also between HA that are in the same Italian Region. It resulted a widespread delay in the replacement of latex devices (e.g. urinary and intravenous catheters) with devices made of alternative materials. However, we found a growing attention towards the procedures related to the purchase of gloves, towards the adoption of guidelines about the use of gloves and towards the training and the information of health care workers. CONCLUSIONS: From this study it has emerged clear the need of Italian HA to focus on the prevention of latex allergy, goal already obtained in a few, almost isolated, realities.

[Follow-up of latex-induced occupational asthma]. / Follow up dell'asma professionale da latice.

We studied 29 subjects with latex-induced occupational asthma in a follow-up of 5 +/- 3 years. Initial and follow-up visits included a questionnaire and measurement of lung volumes, bronchial responsiveness to methacholine (PD20FEV1), and latex-specific serum IgE levels. At follow-up, 17 subjects were no longer exposed to latex, whereas 12 subjects had reduced exposure. Asthma and rhinitis symptoms, use of steroids and bronchial hyperresponsiveness improved significantly at follow-up, whereas mean FEV1% and FVC% decreased (p < 0.05). Multiple regression analysis showed that the main determinant of FEV1 and PD20FEV1 at follow up were the values of these variables at diagnosis. Complete recovery of occupational asthma was observed in 7 subjects (24%), all in the non-exposed group. Latex-specific IgE did not exhibit significant changes. In conclusion latex-induced occupational asthma improves after a follow-up of 5 +/- 3 years, but a complete recovery occurs in a minority of subjects and is associated with cessation of exposure. Lung function measurements at follow up depend from their impairment at the time of diagnosis.

An epidemiological survey on the allergological importance of some emerging pollens in Italy.

Epidemiological studies on the pollens responsible for allergic diseases throughout Italy are lacking. Routine diagnostic panels consist prevalently of grass, Parietaria, weeds, birch, olive and mugwort. Considering the great variety of Italian geographical areas and the observation of the growing allergological importance of new botanical species (e.g., ambrosia), a survey on pollen species considered "minor" was necessary. A panel of "emerging" pollens (birch, hazelnut, alder, hornbeam, cypress, ragweed) and a routine panel were used to skin prick test 2,934 consecutive outpatients with respiratory pathology of suspected allergic origin, in 21 centers across Italy. A specific questionnaire was compiled. It was found that 20.1% of patients did not react to allergens tested, 28.2% were positive for at least one emerging pollen and 51.7% did not react to emerging pollens but tested positive for at least one allergen from the routine panel. The prevalence of single pollen species was related to geographical areas. Ragweed pollen was shown to provoke asthma much more frequently than other pollens. Hitherto scarcely considered pollens play a considerable role in causing allergic diseases in Italy. In the great majority of patients, positivity for these pollens was associated with positivity to the better recognized group of pollen allergens, although in some cases they were the primary pathogenic agent. We suggest that these more recently considered allergens be included in routine diagnostic panels.

Clinical study on Alternaria spores sensitization.

BACKGROUND: sensitization to fungi spores is often associated with sensitization to other allergens and so it is difficult to estabilish the exact cause of illness. OBJECTIVE: the aim of the study was to evaluate a group of patients monosensitized to Alternaria and to establish the prevalence, periodicity and clinical profile of this kind of sensitization. METHODS: 37 subjects who were monosensitized to Alternaria (prick-test positive), according to a previous epidemiological study were evaluated. Clinical symptoms and the period of their occurrence were taken into consideration as well as immunological parameters (RAST). RESULTS: 20 patients (over 50%) included in the study proved to be affected by asthma associated with other allergic symptoms and 22 patients (60%) presented perennial symptoms. The RAST carried out on 34 monosensitized subjects proved positive in 11 and negative in 23. CONCLUSIONS: Alternaria sensitization is characterized by a perennial periodicity with severe respiratory symptoms (asthma) which occur primarily in children. Prick test is preferable to and more reliable than RAST as a diagnostic test.

Clinical study on Alternaria spores sensitization

Background: sensitization to fungi spores is often associated with sensitization to other allergens and so it is difficult to estabilish the exact cause of illness. Objective: the aim of the study was to evaluate a group of patients monosensitized to Alternaria and to establish the prevalence, periodicity and clinical profile of this kind of sensitization. Methods: 37 subjects who were monosensitized to Alternaria (prick-test positive), according to a previous epidemiological study were evaluated. Clinical symptoms and the period of their occurrence were taken into consideration as well as immunological parameters (RAST). Results: 20 patients (over 50%) included in the study proved to be affected by asthma associated with other allergic symptoms and 22 patients (60%) presented perennial symptoms. The RAST carried out on 34 monosensitized subjects proved positive in 11 and negative in 23. Conclusions: Alternaria sensitization is characterized by a perennial periodicity with severe respiratory symptoms (asthma) which occur primarily in children. Prick test is preferable to and more reliable than RAST as a diagnostic test (AU)

Introducción: la sensibilización a esporas de hongos se asocia frecuentemente con la sensibilización a otros alergenos, con lo que es difícil establecer la causa exacta de la enfermedad. Objetivo: la finalidad del estudio fue evaluar a grupos de pacientes monosensibilizados a Alternaria y establecer la prevalencia, periodicidad y perfil clínico de esta clase de sensibilización. Métodos: se estudiaron 37 pacientes monosensibilizados a Alternaria (prick test positivo) seleccionados en un estudio epidemiológico previo. También se consideraron los síntomas clínicos y su frecuencia, así como algunos parámetros inmunológicos (RAST). Resultado: 20 pacientes (por encima del 50 por ciento) padecían asma asociada con otros síntomas alérgicos y 22 pacientes (60 por ciento) presentaban síntomas perennes. El RAST llevado a cabo en 34 pacientes monosensibilizados, fue positivo en 11 y negativo en 23. Conclusiones: la sensibilización a Alternaria se caracterizó por ser perenne, cursar con síntomas respiratorios graves (asma) y tener lugar principalmente en niños. Es preferible y más fiable como test diagnóstico el test cutáneo que el RAST. (AU)

Effect of natural grass pollen exposure on exhaled nitric oxide in asthmatic children.

Exhaled nitiric oxide (NO) is increased in exhaled breath of asthmatic patients. The aim of this study was to investigate the longitudinal changes of exhaled NO outside and during the pollen season in pollen-allergic asthmatic children. Twenty-one children (age 6 to 16 yr), with a seasonal allergic asthma sensitive to grass pollen, underwent measurements of exhaled NO and pulmonary function before (March), during (May), and after (November) the pollen season. Exhaled NO was measured by a tidal breathing method with a chemiluminescence analyzer and NO steady-state levels were recorded. The timing of the measurements during the pollen season was based on the atmospheric pollen count. Exhaled NO values of asthmatic children were compared with those of 21 sex- and age-matched healthy children. Pulmonary function and symptoms of asthma were also evaluated at each visit. The mean value of exhaled NO before the grass season was 12.7 +/- 5.1 ppb (mean +/- SD), significantly higher when compared with controls (7.8 +/- 2.7 ppb, p < 0.001). In the pollen season there was a significant (p < 0.001) twofold increase in exhaled NO (21.4 +/- 7.6 ppb) that, after the season, returned to values similar (12.8 +/- 5.8 ppb, p = NS) to those found before the season. There were no significant changes in FEV1 before and during the season (98.6% predicted versus 101% predicted, p = NS). We conclude that natural allergen exposure is related to an increase of exhaled NO in asthmatic grass pollen-allergic children even in absence of significant changes in airways function. We speculate that measurement of exhaled NO could be a sensitive noninvasive marker of asthma disease activity.