Glassforming Liquids, Amorphous and Semicrystalline Polymers: Exploring their Energy Landscape and Dynamical Heterogeneity by Multi-frequency High-Field EPR

We review past and recent work carried out on viscous liquids, amorphous and semicrystalline polymers by multifrequency high-field electron paramagnetic resonance (HF-EPR) facility in Pisa. The emphasis is on the enhanced ability to provide fine details of the reorientation process of the paramagnetic guest, the spin probe, revealing features driving the dynamics of the host system, including the energy-barrier distribution of glassy polymers, the dynamical heterogeneity of semicrystalline polymers, and the dynamical changes occurring at the critical temperature predicted by the ideal mode-coupling theory

Usefulness of a simple sleep-deprived EEG protocol for epilepsy diagnosis in de novo subjects.

OBJECTIVE: In case series concerning the role of EEG after sleep deprivation (SD-EEG) in epilepsy, patients' features and protocols vary dramatically from one report to another. In this study, we assessed the usefulness of a simple SD-EEG method in well characterized patients. METHODS: Among the 963 adult subjects submitted to SD-EEG at our Center, in the period 2003-2010, we retrospectively selected for analysis only those: (1) evaluated for suspected epileptic seizures; (2) with a normal/non-specific baseline EEG; (3) still drug-free at the time of SD-EEG; (4) with an MRI analysis; (5) with at least 1year follow-up. SD-EEG consisted in SD from 2:00 AM and laboratory EEG from 8:00 AM to 10:30 AM. We analyzed epileptic interictal abnormalities (IIAs) and their correlations with patients' features. RESULTS: Epilepsy was confirmed in 131 patients. SD-EEG showed IIAs in 41.2% of all patients with epilepsy, and a 91.1% specificity for epilepsy diagnosis; IIAs types observed during SD-EEG are different in generalized versus focal epilepsies; for focal epilepsies, the IIAs yield in SD-EEG is higher than in second routine EEG. CONCLUSIONS: This simple SD-EEG protocol is very useful in de novo patients with suspected seizures. SIGNIFICANCE: This study sheds new light on the role of SD-EEG in specific epilepsy populations

Prolonged epileptic discharges predict seizure recurrence in JME: Insights from prolonged ambulatory EEG

Objective: Markers of seizure recurrence are needed to personalize antiseizure medication (ASM) therapy. In the clinical practice, EEG features are considered to be related to the risk of seizure recurrence for genetic generalized epilepsies (GGE). However, to our knowledge, there are no studies analyzing systematically specific EEG features as indices of ASM efficacy in GGE. In this study, we aimed at identifying EEG indicators of ASM responsiveness in Juvenile Myoclonic Epilepsy (JME), which, among GGE, is characterized by specific electroclinical features. Methods: We compared the features of prolonged ambulatory EEG (paEEG, 22 h of recording) of JME patients experiencing seizure recurrence within a year (“cases”) after EEG recording, with those of patients with sustained seizure freedom for at least 1 year after EEG (“controls”). We included only EEG recordings of patients who had maintained the same ASM regimen (dosage and type) throughout the whole time period from the EEG recording up to the outcome events (which was seizure recurrence for the “cases”, or 1-year seizure freedom for “controls”). As predictors, we evaluated the total number, frequency, mean and maximum duration of epileptiform discharges (EDs) and spike density (i.e. total EDs duration/artifact-free EEG duration) recorded during the paEEG. The same indexes were assessed also in standard EEG (stEEG), including activation methods. Results: Both the maximum length and the mean duration of EDs recorded during paEEG significantly differed between cases and controls; when combined in a binary logistic regression model, the maximum length of EDs emerged as the only valid predictor. A cut-off of EDs duration of 2.68 seconds discriminated between cases and controls with a 100% specificity and a 93% sensitivity. The same indexes collected during stEEG lacked both specificity and sensitivity. Significance: The occurrence of prolonged EDs in EEG recording might represent an indicator of antiepileptic drug failure in JME patients

Unravelling main- and side-chain motions in polymers with NMR spectroscopy and relaxometry: The case of polyvinyl butyral

Polyvinyl butyral (PVB) is an amorphous polymer employed in many technological applications. In order to highlight the relationships between macroscopic properties and dynamics at a microscopic level, motions of the main-chain and of the propyl side-chains were investigated between Tg − 288◦ C and Tg + 55◦ C, with Tg indicating the glass transition temperature. To this aim, a combination of solid state Nuclear Magnetic Resonance (NMR) methods was applied to two purposely synthesized PVB isotopomers: one fully protonated and the other perdeuterated on the side-chains.1 H time domain NMR and1 H field cycling NMR relaxometry experiments, performed across and above Tg, revealed that the dynamics of the main-chain corresponds to the α-relaxation associated to the glass transition, which was previously characterized by dielectric spectroscopy. A faster secondary relaxation was observed for the first time and ascribed to side-chains. The geometry and rate of motions of the different groups in the side-chains were characterized below Tg by2 H NMR spectroscopy

Controversial issues on EEG after sleep deprivation for the diagnosis of epilepsy

EEG after sleep deprivation (SD-EEG) is widely used in many epilepsy centers as an important tool in the epilepsy diagnosis process. However, after more than 40 years of use, there are a number of issues which still need to be clarified concerning its features and role. In particular, the many scientific papers addressing its role in epilepsy diagnosis often differ remarkably from each other in terms of the type of patients assessed, their description and study design. Furthermore, also the length and the type of EEG performed after SD, as well as the length of SD itself, vary dramatically from one study to another. In this paper we shortly underscore the abovementioned differences among the different reports, as well as some interpretations of the findings obtained in the different studies. This analysis emphasizes, if needed, how SD-EEG still represents a crucial step in epilepsy diagnosis, and how additional, controlled studies might further shape its precise diagnostic/prognostic role

Daytime sleepiness in de novo untreated patients with epilepsy.

The aims of our study were to evaluate excessive daytime sleepiness in a group of de novo untreated people with epilepsy using a comprehensive and standardized approach, including subjective evaluation and neurophysiological and performance tests, and to compare these results with those obtained in a control group. Forty-seven patients with epilepsy (17 affected by primary generalized epilepsy and 30 by partial epilepsy), with a new epilepsy diagnosis and never treated, and 44 controls underwent Multiple Sleep Latency Test (preceded by nocturnal polysomnography), simple/complex visual reaction times, and Epworth Sleepiness Scale evaluation. Newly diagnosed and drug-free patients with epilepsy did not differ from controls in any of the tests performed to evaluate daytime sleepiness. In clinical practice, daytime sleepiness is a well-known and frequent complaint of patients with epilepsy, but different mechanisms and causes, such as associated psychiatric or sleep disorders, nocturnal seizures, sleep fragmentation, and antiepileptic drugs, must be taken into account. Excessive daytime sleepiness should not be considered an unavoidable consequence of epilepsy. Thus, a complete diagnostic work-up in patients with epilepsy and sleepiness should be undertaken whenever possible

Attributing scientific and technical progress: the case of holography

Holography, the three-dimensional imaging technology, was portrayed widely as a paradigm of progress during its decade of explosive expansion 1964–73, and during its subsequent consolidation for commercial and artistic uses up to the mid 1980s. An unusually seductive and prolific subject, holography successively spawned scientific insights, putative applications and new constituencies of practitioners and consumers. Waves of forecasts, associated with different sponsors and user communities, cast holography as a field on the verge of success—but with the dimensions of success repeatedly refashioned. This retargeting of the subject represented a degree of cynical marketeering, but was underpinned by implicit confidence in philosophical positivism and faith in technological progressivism. Each of its communities defined success in terms of expansion, and anticipated continual progressive increase. This paper discusses the contrasting definitions of progress in holography, and how they were fashioned in changing contexts. Focusing equally on reputed ‘failures’ of some aspects of the subject, it explores the varied attributes by which success and failure were linked with progress by different technical communities. This important case illuminates the peculiar post-World War II environment that melded the military, commercial and popular engagement with scientific and technological subjects, and the competing criteria by which they assessed the products of science

Sustained seizure freedom with adjunctive brivaracetam in patients with focal onset seizures

The maintenance of seizure control over time is a clinical priority in patients with epilepsy. The aim of this study was to assess the sustained seizure frequency reduction with adjunctive brivaracetam (BRV) in real-world practice. Patients with focal epilepsy prescribed add-on BRV were identified. Study outcomes included sustained seizure freedom and sustained seizure response, defined as a 100% and a ≥50% reduction in baseline seizure frequency that continued without interruption and without BRV withdrawal through the 12-month follow-up. Nine hundred ninety-four patients with a median age of 45 (interquartile range = 32–56) years were included. During the 1-year study period, sustained seizure freedom was achieved by 142 (14.3%) patients, of whom 72 (50.7%) were seizure-free from Day 1 of BRV treatment. Sustained seizure freedom was maintained for ≥6, ≥9, and 12 months by 14.3%, 11.9%, and 7.2% of patients from the study cohort. Sustained seizure response was reached by 383 (38.5%) patients; 236 of 383 (61.6%) achieved sustained ≥50% reduction in seizure frequency by Day 1, 94 of 383 (24.5%) by Month 4, and 53 of 383 (13.8%) by Month 7 up to Month 12. Adjunctive BRV was associated with sustained seizure frequency reduction from the first day of treatment in a subset of patients with uncontrolled focal epilepsy

Phenyl ring dynamics in a liquid crystal polymer through H-2 NMR spectroscopy

The dynamics of a side chain liquid crystal copolymer at two dierent compositions has been investigated in its smectic A and C phases. J1x0 and J22x0 spectral densities have been determined for aromatic deuterium nuclei in the side chains and their interpretation has been carried out by means of several available motional models. The dy- namic process mainly contributing to relaxation has been found to be the rotation of the phenyl ring about its para-axis, that is best described by a small step rotational diusion model, where the diusion constant has an Arrhenius tem- perature dependence and a Gaussian distribution of the activation energies is present, indicating a remarkable degree of dynamic heterogeneity of this system