Postprandial glucose variability in type 1 diabetes: The individual matters beyond the meal.

AIM: To explore intraindividual (between-meals) and interindividual (between-subjects) variability of postprandial glucose response (PGR) in type 1 diabetes (T1DM). METHODS: Data were taken from five cross-over trials in 61 subjects with T1DM on insulin pump wherein the effects of different dietary components or the intraindividual-variability of PGR to the same meal were evaluated by CGM. Predictors (type of meal or nutrient composition) of early (iAUC0-3h), late (iAUC3-6h), total (iAUC0-6h), and time-course of postprandial blood glucose changes (iAUC3-6hminus0-3h) were evaluated using two mixed-effect linear regression models considering the patient's identification number as random-effect. RESULTS: High-glycemic-index (HGI) and low-glycemic-index meals were the best positive and negative predictors of glucose iAUC0-3h, respectively. A Low-Fat-HGI meal significantly predicted iAUC3-6hminus0-3h (Estimate 3268; p = 0.017). Among nutrients, dietary fiber was the only significant negative predictor of iAUC0-3h (Estimate -550; p < 0.001) and iAUC0-6h (Estimate -742; p = 0.01) and positive predictor of iAUC3-6hminus0-3h (Estimate 336; p = 0.043). For all models, the random-effect patient was statistically significant (p < 0.001 by ANOVA). CONCLUSION: Beyond the meal characteristics (including glycemic index, fat and fiber content), individual traits significantly influence PGR. Specific interindividual factors should be further identified to properly predict glucose response to meals with different composition in individuals with T1DM.

The Easy Thing (ET) observational study: evaluation of adherence to Mediterranean diet and role of a program of nutritional intervention performed by North Naples 2 Local Health Unit.

OBJECTIVE: The present observational study has the aim to describe the nutritional habits and adherence to Mediterranean diet within a dietary intervention performed by North Naples 2 Local Health Unit in some areas of Campania region. PATIENTS AND METHODS: A semi-quantitative food frequency questionnaire which takes in consideration several kinds of food and the related daily or weekly portions has been administered to people evaluated in the study. An increased score reflects an increased adherence to Mediterranean diet. Patients have been grouped by age, body mass index, education, socio-economic level, income, and score reported to the administered survey. Nutritional intervention has also been evaluated as concerns weight reduction during time. RESULTS: Surveys were administered to 200 patients aged from 12 to 79 years from 21 November 2018 to 27 November 2019. Obese patients were 61.5% in this population. 67.7% of obese people participating to this study had primary/lower secondary school education. 61.5% of study population have been categorized as having a low or low-medium socio-economic level and 68% of them were obese. An intermediate adherence to Mediterranean Diet has been the most represented (76.5%), a significant difference has been found among the groups normal weight, overweight and obese for the variables age, education and income. Obese patients in the present study had metabolic diseases more frequently than normal-weight patients. CONCLUSIONS: A high rate of obese people requesting nutritional counseling showed intermediate/bad adherence to Mediterranean Diet, reflecting the diffuse change from Mediterranean Diet to Western habits in nutrition. The nutritional intervention was found to be effective, especially for overweight patients. These data underline the need for further larger epidemiological analysis and public health interventions.

Application of the Tikhonov tomography method for the gas electron multiplier (GEM) system on experimental advanced superconducting tokamak.

A novel GEM (Gas Electron Multiplier) system has been installed on experimental advanced superconducting tokamak (EAST) which is used for collecting the line integral of the soft X-ray radiation (SXR) through a pinhole-collimated Beryllium window. The sightline of the 2-D GEM system is tangential to the toroidal field. To obtain the local SXR emission, the Tikhonov algorithm is applied for the imaging of the poloidal cross section emission in the vacuum vessel. In the meanwhile, the L-curve method is used to find an optimized solution of the regularization parameters. The tomography reliability has been tested with a known emission function where the error is also discussed. The tomography method has been coded as a graphic user interface for the fast analysis of GEM experimental data. The typical tomography results have been shown for the EAST shot (#79282) in this paper.

The GEMpix detector as new soft X-rays diagnostic tool for laser produced plasmas.

Laser produced plasmas lend to several interesting applications. The study of X-ray emission from this kind of plasmas is important not only to characterize plasmas itself but also to study the application of these particular plasmas as intense X-ray sources. In particular several emission configurations can be obtained using different kinds of targets and tuning the characteristics of the laser pulse delivered to the target. Typically, laser pulse duration ranges between a few tens of femtoseconds and tens of nanoseconds, with energies from few mJ to tens of kJ. X-ray photon emissions last for times comparable to the laser pulses and during this time a great number of photons can be emitted. The following paper presents a measure of the soft-X-ray emission on the ECLIPSE laser facility realized with a new triple-GEM gas detector (GEMpix). It is a hybrid gas detector with a C-MOS front-end electronics based on Medipix chips. In the present work, different targets have been used in order to test X-rays of different energies. In this paper, in particular, we present results obtained for copper and iron targets. GEMpix is able to realize a 2D imaging of the X-ray emission from plasma with a signal proportional to the energy released in the gas of the detector active volume. Then through a preliminary single photon equalization realized at the NIXT lab (ENEA), also the number of photons reaching the area of the detector has been estimated.

Installation of soft X-ray array diagnostics and its application to tomography reconstruction using synthetic KSTAR X-ray images.

Four-array system of soft X-ray diagnostics was installed on KSTAR tokamak. Each array has 32 viewing chords of two photo-diode array detectors with spatial resolution of 2 cm. To estimate signals from the soft X-ray radiation power, typical ne, Te, and argon impurity line radiation profiles in KSTAR are chosen. The photo-diodes were absolutely calibrated as a function of the incident photon energy in 2-40 keV range with a portable X-ray tube. Two-dimensional Te image properties by multi-energy method were simulated and visualized with six combinations of beryllium filter sets within the dynamic range of signal ratio.

Soft x-ray tomography for real-time applications: present status at Tore Supra and possible future developments.

This paper is focused on the soft x-ray (SXR) tomography system setup at Tore Supra (DTOMOX) and the recent developments made to automatically get precise information about plasma features from inverted data. The first part describes the main aspects of the tomographic inversion optimization process. Several observations are made using this new tool and a set of shape factors is defined to help characterizing the emissivity field in a real-time perspective. The second part presents a detailed off-line analysis comparing the positions of the magnetic axis obtained from a magnetic equilibrium solver, and the maximum of the reconstructed emissivity field for ohmic and heated pulses. A systematic discrepancy of about 5 cm is found in both cases and it is shown that this discrepancy increases during sawtooth crashes. Finally, evidence of radially localized tungsten accumulation with an in-out asymmetry during a lower hybrid current drive pulse is provided to illustrate the DTOMOX capabilities for a precise observation of local phenomena.

Characterization of a 2D soft x-ray tomography camera with discrimination in energy bands.

A gas detector with a 2D pixel readout is proposed for a future soft x-ray (SXR) tomography with discrimination in energy bands separately per pixel. The detector has three gas electron multiplier foils for the electron amplification and it offers the advantage, compared with the single stage, to be less sensitive to neutrons and gammas. The energy resolution and the detection efficiency of the detector have been accurately studied in the laboratory with continuous SXR spectra produced by an electronic tube and line emissions produced by fluorescence (K, Fe, and Mo) in the range of 3-17 keV. The front-end electronics, working in photon counting mode with a selectable threshold for pulse discrimination, is optimized for high rates. The distribution of the pulse amplitude has been indirectly derived by means of scans of the threshold. Scans in detector gain have also been performed to assess the capability of selecting different energy ranges.

An original calibration technique for soft x-ray detectors and its use in the Tore Supra tomographic system.

This paper describes in detail the recent progresses which have been made in Tore Supra for developing a new technique of calibration of the soft x-ray (SXR) detectors in the range 1-30 keV. The diode response as a function of the flux of photons resulted accurately linear over almost three orders of magnitude. Apart from a limited number of deficient detectors, promptly replaced with new ones, the spread of the diode responses (84 detectors) is about 20% total of the average value. It allowed the derivation of the calibration factor for each detector of the tomography system. The effect of the environmental temperature, in the range 15 degrees-40 degrees, has also been studied, revealing that up to 35 degrees the linearity of diode response and these calibration factors remain constant. It demonstrates the capability of discriminating slight and localized changes in the two dimensional spatial distribution of the SXR intensity.

Characterization of detection efficiency as function of energy for soft x-ray detectors.

A new technique has been especially developed for determining the detection efficiency of the silicon surface barrier diodes used for tomography reconstructions at Tore Supra, as function of the energy of the x-ray photons, in the range of 4-25 keV. The response of these diodes has been studied for different bias voltages (0-120 V), with a portable x-ray electronic tube and a cooled Si-p-i-n diode, working in photon counting mode, for the absolute calibration.

Observations of the vacuum ultraviolet and x-ray brightness profiles of Fe, Ni, and Ge in magnetically confined fusion plasmas.

The spatial brightness profiles of emission lines for the K-like through He-like ionization states of Fe, Ge, and Ni have been measured during a set of experiments in which Fe and Ge were introduced into FTU tokamak plasmas by using the laser blowoff technique. Nickel was an intrinsic impurity observed during these experiments that was sputtered from the inconel limiter. The brightness profiles were measured by spatially scanable, photometrically calibrated vaccum ultraviolet and x-ray spectrometers that covered the 1 to 1700 A region. Simulations of these profiles and the time evolution of the laser blowoffs were performed with the MIST transport code using several sets of atomic physics compilations [ADPAK (originally in MIST), Arnaud and Raymond (AR92), Arnaud and Rothenflug (AR85), Mazzotta et al., and Mattioli (an extension to Mazzotta)]. The goal was to determine which set of available rates could best simulate the measured spatial brightness profiles and the charge state balance in the plasma. The Mazzotta et al. (for Fe and Ni), the Mattioli (for Ge), and the AR92 (for Fe only) rates adequately simulated the He-, Li-, Be-, Na-, Mg-like ionization states. The F- to B-like charge states could not be simulated by these compilations unless the relevant dielectronic rates were multiplied by a factor of 2. The ADPAK rates could not adequately predict any of the charge states of Fe, Ge, or Ni.

Temperature and impurity transport studies of heated tokamak plasmas by means of a collisional-radiative model of x-ray emission from Mo30+ to Mo39+

This work presents and interprets, by means of detailed atomic calculations, observations of L-shell (n = 3-->n = 2) transitions in highly ionized molybdenum, the main intrinsic heavy impurity in the Frascati tokamak upgrade plasmas. These hot plasmas were obtained by additional electron cyclotron resonance heating (ECRH), at the frequency of 140 Ghz, during the current ramp-up phase of the discharge. Injecting 400 kW on axis and 800 kW slightly off axis, the peak central electron temperature reached 8.0 and 7.0 keV, respectively, for a time much longer than the ionization equilibrium time of the molybdenum ions. X-ray emissions from rarely observed high charge states, Mo30+ to Mo39+, have been studied with moderate spectral resolution (lambda/delta lambda approximately 150) and a time resolution of 5 ms. A sophisticated collisional-radiative model for the study of molybdenum ions in plasmas with electron temperature in the range 4-20 keV is presented. The sensitivity of the x-ray emission to the temperature and to impurity transport processes is discussed. This model has been then used to investigate two different plasma scenarios. In the first regime the ECRH heating occurs on axis during the current ramp up phase, when the magnetic shear is evolving from negative to zero up to the half radius. The spectrum is well reproduced with the molybdenum ions in coronal equilibrium and with a central impurity peaking. In the second regime, at the beginning of the current flat top when magnetic shear is monotonic and sawtoothing activity is appearing, the lowest charge states (Mo33+ to Mo30+), populated off axis, are affected by anomalous transport and the total molybdenum profile is found to be flat up to the half radius. We conclude with the presentation of "synthetic spectra" computed for even higher temperature plasmas that are expected in future experiments with higher ECRH power input.