Search

Background and study purpose: to describe the comorbidity of celiac disease among a large cohort of multiple sclerosis patients in Tuscany. Methods: the association of celiac disease among multiple sclerosis adult patients (n=2050) was retrospectively evaluated. Results: 13 patients were diagnosed with celiac disease, the female:male ratio was 3.3:1 and the median age at diagnosis was 34.2 years (SD 13). Seventy-seven per cent of subjects complained about gastrointestinal symptoms. IgA anti- transglutaminase was positive in 85 % of cases and there was 70 % of villous atrophy. Conclusions: the frequency of celiac disease among multiple sclerosis patients examined was lower than in the general population, 0.6 % vs 1 %)(p = 0.65).

Dysfunctions of the upper limbs occur in the 66% of multiple sclerosis (MS) patients. To date, no data, about the persistence of the effects of a rehabilitation treatment and no prognostic markers of functional improvement, have been established.The aim of this study was to define clinical data supporting the efficacy of a rehabilitation treatment in MS patients with upper limb impairment and to find prognostic factors for functional improvement.Pre-post comparison prospective study.Two tertiary Italian MS centres: Rome and Siena.Twenty-five consecutive MS patients were tested for eligibility.We multidimensionally evaluated 25 consecutive patients with MS-related upper limbs impairment through clinical objective, patient-oriented and neurophysiological measures pre and post a16-week rehabilitation treatment on upper limb sensorimotor function.We found a significant improvement in the Nine Hole Peg Test (9-HPT) at either sides, both at an immediate post-training visit (T1) (left: P=0.018, right: P=0.004) and at a 12-week postintervention assessment visit (T2) (left: P=0.033, right: P=0.022). We also found a positive correlation between the 12-week post-training changes in the 9-HPT and the N14-P20 interpeak of the somatosensory evoked potentials, (rho=0.374, P=0.008).Our study demonstrates that a rehabilitation treatment can lead to an improvement of the upper limb motor performance in MS patients which continues to persist even after 3 months of treatment-discontinuation suggesting a possible role of rehabilitation in neuroplasticity changes. Moreover, we found, in the latency of the N14-P20 interpeak, a possible prognostic marker for the effects of a upper limb rehabilitation treatment in MS patients.The N14-P20 interpeak could be used as a prognostic marker of the effects of rehabilitation of the upper limb.

Optical resonators are well-established tools commonly used in spectroscopy, they have widespread applications over the whole electromagnetic spectrum, while record-level optical finesses were achieved in the visible/near-IR. In this context, the THz portion of the electromagnetic spectrum is still lacking of such tools. One reason is certainly that, for many years, the THz range has been an underexploited region. However, recent advances in generation and detection of THz radiation, as well as the advent of novel THz-emitting laser sources, such as quantum cascade lasers (QCLs), and the constantly evolving technology of new materials, are now making THz light emerge as a new promising frontier for interdisciplinary research areas. However, among the number of different applications of THz radiation, a central role is played by molecular spectroscopy. In order to further increase the sensitivity of a spectroscopic system, high-finesse cavity resonators represent an attractive tool as they give access to much longer interaction lengths between light and absorbing medium, and could also provide a narrow reference for a QCL, allowing a reduction of its free-running linewidth.We report on two different resonant cavities designs, injected by a continuous-wave quantum cascade laser emitting at 2.55 THz [1]. The two cavities are a V-shaped and a ring shaped resonator, the input/output couplers of both cavities are wire grid polarizers, acting as highly reflective mirrors, and each cavity is equipped with a shifting mirror, in order to tune the cavity length. The achieved ring-cavity finesse is about 63, corresponding to a Q-factor of 2.6×10-5. Due to its geometrical configuration, the V-shaped resonator produces an optical feedback to the QCL, when in resonance. This optical feedback (OF) prevents an accurate finesse measurements, as it broadens the resonance peak profiles. In order to better understand this effect, we injected both the resonators at the same times; the V-shaped cavity is swept across its resonances, while the ring cavity is kept in a position corresponding to the center of a resonance side. In this conditions, any shift of the laser frequency induced by OF will result in a variation of the signal transmitted by the ring cavity. Experimental data have confirmed this effect, that in the future can be exploited for optically locking the QCL frequency to the V-shaped cavity resonance.

We present the latest results on high-resolution QCL-based THz spectroscopy: the possibility to perform saturated absorption or cavity-enhanced spectroscopy on THz molecular transitions, strengthened by the realization of a new generation THz FCS. © OSA 2015.

Optical feedback and injection locking are two well established techniques allowing for the control of mid infrared quantum cascade lasers (QCLs) emission. The first one, with the laser mounted in an external cavity configuration [1], enables wide tunability of the source. On the other hand, the second one, implemented using a metrological-grade radiation as master [2], enables the transfer of the phase stability of the master oscillator to the QCL radiation. Recently, comb operation in QCLs has been demonstrated [3]. Although a phase relation between the modes has been demonstrated, the comb emission has to be stabilized to be used for high-resolution spectroscopy applications. Optical techniques seem to be good candidates to this task. This aspect will be discussed in detail

High precision THz molecular spectroscopy promises amazing scientific and technological applications, provided that sources with suitable high power, wide tunability and narrow linewidth, such THz Quantum Cascade Lasers [1] are available. In this context, the first application of a QCL phase-locked to a free-standing THz Frequency Comb Synthesizer (FCS) [2] was recently demonstrated, achieving a state of-the-art accuracy of 4×109 in the determination of the absolute frequency of a THz transition [3]. In this experimental report the overall accuracy was limited by the resolution of the Doppler-broadened direct-absorption spectroscopy adopted therein. As a consequence, the the development of high-resolution THz spectroscopic techniques, such as saturatedabsorption spectroscopy (SAS), is a mandatory condition for further accuracy improvements. We therefore report on the evidence of saturation effects in a rotational transition of CH3OH around 2.55 THz, induced by a freerunning continuous-wave QCL [4], confirming the feasibility of QCL-based subDoppler spectroscopy, once provided that the QCL emission linewidth is comparable with, or narrower than the Lamb-dip width. The QCL emission is used for direct-absorption spectroscopy experiments, allowing to study the dependence of the absorption coefficient on gas pressure and laser intensity. A saturation intensity of 25 W/mm2, for a gas pressure of 17 bar, is measured.

A non-conventional cavity ring-down spectroscopic technique is described. When the light intensity is well above the saturation level for the molecular species inside a high-finesse cavity, each single cavity ring-down event simultaneously measures both the background losses from the cavity mirrors and the linear absorption from the gas. Such a differential scheme acting on very short time scales (a few tens of microseconds) can improve the sensitivity of conventional cavity ring-down by more than one order of magnitude, while achieving sub-Doppler resolution, if needed. Applications to optical detection of very rare molecular species like radiocarbon dioxide and resolved molecular hyperfine structure in 17O12C16O are presented.

collection of articles based on oral presentation at the EUMETRISPEC workshop held at Wolfenbüttel castle and PTB Praunschweig, Nov. 15-16, 2012, PTB-Bericht Chemische Physik CP-8. ISSN 1614-953X. ISBN 978-3-95606-034-2., This PTB report comprises all oral presentations and posters presented at the Nov. 2012 workshop on "Spectral reference line data for atmospheric monitoring" held at Wolfenbüttel castle and PTB Braunschweig. The workshop was organized by the EUMETRISPEC project which is part of the European Metrology Research Programme (EMRP). The main aim was to present and discuss the stakeholders' views and needs. The stakeholders are from metrological organisations as well as from ground- and satellite-based monitoring networks and from quantum chemical modelling groups - in total 49 scientists representing 31 institutions from 12 nations. During the workshop, nine invited 45min-talks were given, covering spectroscopic and metrological key topics, accompanied by six additional presentations on EUMETRISPEC and the EMRP. The PTB report includes the authorized powerpoint presentations, as well as all 21 posters from 91 authors presented during the workshop.

Using data from the PRIAMO study, we investigated non-motor symptoms (NMS) versus frontal lobe dysfunction in patients with idiopathic Parkinson disease (PD); 808 patients with PD and 118 with atypical parkinsonisms (AP) were consecutively enrolled at 55 Centers in Italy. Twelve categories of NMS were investigated. Cognitive impairment was defined as a Mini-Mental Status Evaluation score ≤ 23.8 and frontal lobe dysfunction as a Frontal Assessment Battery (FAB) score ≤ 3.48. Multivariable logistic regression was used to identify predictor of frontal lobe dysfunction in 524 PD patients, and a generalized linear model was used for each of the six FAB items. Not only the total FAB scores but also the single FAB items were lower in AP versus PD (p ≤ 0.005). Age (OR = 1.05), cognitive impairment (OR = 9.54), lack of cardiovascular symptoms (OR = 3.25), attention or memory problems (OR = 0.59) and treatment with L: -DOPA (OR = 5.58) were predictors of frontal lobe dysfunction. MMSE was negatively associated with all FAB items (β ≤ -0.16) and age with all FAB items but prehension behavior (β ≤ -0.01). Previous use of L: -DOPA was negatively associated with verbal fluency (β = -0.32) possibly acting as surrogate marker of disease duration. Cognitive impairment is a predictor of frontal lobe dysfunction. Among NMS, lack of attention or memory problems were negatively associated with frontal impairment. Further studies are nonetheless needed to better identify the predictors of frontal impairment in PD patients.

A frequency-comb-referenced difference-frequency-generated cw mid-IR source is combined with the saturated-absorption cavity ring-down spectroscopic technique to achieve optical detection of radiocarbon dioxide in natural and enriched abundance.