Polariton propagation in weak confinement quantum wells

Exciton-polariton propagation in a quantum well, under centre-of-mass quantization, is computed by a variational self-consistent microscopic theory. The Wannier exciton envelope functions basis set is given by the simple analytical model of ref. [1], based on pure states of the centre-of-mass wave vector, free from fitting parameters and "ad hoc" (the so called additional boundary conditions-ABCs) assumptions. In the present paper, the former analytical model is implemented in order to reproduce the centre-of-mass quantization in a large range of quantum well thicknesses (5a_B < L < inf.). The role of the dynamical transition layer at the well/barrier interfaces is discussed at variance of the classical Pekar's dead-layer and ABCs. The Wannier exciton eigenstates are computed, and compared with various theoretical models with different degrees of accuracy. Exciton-polariton transmission spectra in large quantum wells (L>> a_B) are computed and compared with experimental results of Schneider et al.\cite{Schneider} in high quality GaAs samples. The sound agreement between theory and experiment allows to unambiguously assign the exciton-polariton dips of the transmission spectrum to the pure states of the Wannier exciton center-of-mass quantization.Comment: 15 pages, 15 figures; will appear in Phys.Rev.

Consensus protocol for EEG and amplitude-integrated EEG assessment and monitoring in neonates

The aim of this work is to establish inclusive guidelines on electroencephalography (EEG) applicable to all neonatal intensive care units (NICUs). Guidelines on ideal EEG monitoring for neonates are available, but there are significant barriers to their implementation in many centres around the world. These include barriers due to limited resources regarding the availability of equipment and technical and interpretive round-the-clock personnel. On the other hand, despite its limitations, amplitude-integrated EEG (aEEG) (previously called Cerebral Function Monitor [CFM]) is a common alternative used in NICUs. The Italian Neonatal Seizure Collaborative Network (INNESCO), working with all national scientific societies interested in the field of neonatal clinical neurophysiology, performed a systematic literature review and promoted interdisciplinary discussions among experts (neonatologists, paediatric neurologists, neurophysiologists, technicians) between 2017 and 2020 with the aim of elaborating shared recommendations. A consensus statement on videoEEG (vEEG) and aEEG for the principal neonatal indications was established. The authors propose a flexible frame of recommendations based on the complementary use of vEEG and aEEG applicable to the various neonatal units with different levels of complexity according to local resources and specific patient features. Suggestions for promoting cooperation between neonatologists, paediatric neurologists, and neurophysiologists, organisational restructuring, and teleneurophysiology implementation are provided

Exact solution of the Schrodinger equation for Wannier excitons on a microsphere

The effective-mass Schrodinger equation for an electron and a hole, confined to the surface of a sphere and interacting via the Coulomb potential, is studied. The exact energies and wavefunctions of the optically allowed exciton states are presented. Wavefunctions are expanded as series of polynomials which satisfy an equation of the same order but with a smaller number of singularities

Exact solution of the Schrodinger equation for Wannier excitons on a microsphere

The effective-mass Schrodinger equation for an electron and a hole, confined to the surface of a sphere and interacting via the Coulomb potential, is studied. The exact energies and wavefunctions of the optically allowed exciton states are presented. Wavefunctions are expanded as series of polynomials which satisfy an equation of the same order but with a smaller number of singularities

Peripheral markers of the gamma-aminobutyric acid (GABA)ergic system in Angelman's syndrome

It has recently been demonstrated that patients with Angelman's syndrome who exhibited a deletion on cytogenetic tests show more severe clinical pictures with drug-resistant epilepsy than patients with Angelman's syndrome not carrying the deletion. To verify if this difference in clinical severity can be attributed to genes for the threey-aminobutyric acid (GABA)(A) receptor subunits (GABRB3, GABRA5, GABRG3) located in the deleted region, a possible modification of peripheral markers of the GABAergic system was investigated in 12 subjects with Angelman's syndrome and 20 age-matched subjects (8 with idiopathic epilepsy and 12 not affected by neurologic diseases). The results confirmed a more severe clinical picture, and epilepsy syndrome in particular, in Angelman's syndrome patients with deletions versus patients without deletions. In contrast, biochemical study (based on dosage of plasma levels of GABA and diazepam binding inhibitor, an endogenous ligand of GABA(A) and peripheral benzodiazepine receptors, showed contradictory results: patients with Angelman's syndrome showed significantly higher levels of GABA and diazepam binding inhibitor than patients without neurologic impairment but significantly lower levels than epileptic controls

Electroclinical presentation and genotype-phenotype relationships in patients with Unverricht-Lundborg disease carrying compound heterozygous CSTB point and indel mutations

Purpose: Unverricht-Lundborg disease (EPM1A) is frequently due to an unstable expansion of a dodecamer repeat in the CSTB gene, whereas other types of mutations are rare. EPM1A due to homozygous expansion has a rather stereotyped presentation with prominent action myoclonus. We describe eight patients with five different compound heterozygous CSTB point or indel mutations in order to highlight their particular phenotypical presentations and evaluate their genotype-phenotype relationships. Methods: We screened CSTB mutations by means of Southern blotting and the sequencing of the genomic DNA of each proband. CSTB messenger RNA (mRNA) aberrations were characterized by sequencing the complementary DNA (cDNA) of lymphoblastoid cells, and assessing the protein concentrations in the lymphoblasts. The patient evaluations included the use of a simplified myoclonus severity rating scale, multiple neurophysiologic tests, and electroencephalography (EEG)-polygraphic recordings. To highlight the particular clinical features and disease time-course in compound heterozygous patients, we compared some of their characteristics with those observed in a series of 40 patients carrying the common homozygous expansion mutation observed at the C. Besta Foundation, Milan, Italy. Key Findings: The eight compound heterozygous patients belong to six EPM1A families (out of 52; 11.5%) diagnosed at the Laboratory of Genetics of the Galliera Hospitals in Genoa, Italy. They segregated five different heterozygous point or indel mutations in association with the common dodecamer expansion. Four patients from three families had previously reported CSTB mutations (c.67-1G&gt;C and c.168+1-18del); one had a novel nonsense mutation at the first exon (c.133C&gt;T) leading to a premature stop codon predicting a short peptide; the other three patients from two families had a complex novel indel mutation involving the donor splice site of intron 2 (c.168+2-169+21delinsAA) and leading to an aberrant transcript with a partially retained intron. The protein dose (cystatin B/\u3b2-actin) in our heterozygous patients was 0.24 \ub1 0.02, which is not different from that assessed in patients bearing the homozygous dodecamer expansion. The compound heterozygous patients had a significantly earlier disease onset (7.4 \ub1 1.7 years) than the homozygous patients, and their disease presentations included frequent myoclonic seizures and absences, often occurring in clusters throughout the course of the disease. The seizures were resistant to the pharmacologic treatments that usually lead to complete seizure control in homozygous patients. EEG-polygraphy allowed repeated seizures to be recorded. Action myoclonus progressively worsened and all of the heterozygous patients older than 30 years were in wheelchairs. Most of the patients showed moderate to severe cognitive impairment, and six had psychiatric symptoms. Significance: EPM1A due to compound heterozygous CSTB mutations presents with variable but often markedly severe and particular phenotypes. Most of our patients presented with the electroclinical features of severe epilepsy, which is unexpected in homozygous patients, and showed frequent seizures resistant to pharmacologic treatment. The presence of variable phenotypes (even in siblings) suggests interactions with other genetic factors influencing the final disease presentation. \ua9 2012 International League Against Epilepsy

A pilot trial of levetiracetam in eyelid myoclonia with absences (Jeavons syndrome).

Objective: Eyelid myoclonia with absences (EMA) or Jeavons syndrome characterized by eyelid myoclonia (EM) (with or without absences), eye closure-induced EEG paroxysms, and photosensitivity. We conducted an open-label trial of levetiracetam in EMA. Patients and Methods: Patients were recruited in different Italian Epilepsy Centres. Levetiracetam was administrated at starting dose of 10 mg/kg/day up to 50-60 mg/kg/day in two doses. Treatment period included a 5-6 week up-titration phase and a 12-week evaluation phase. The number of days with EM (i.e., days with seizures, DwS) and number of generalized tonic-clonic seizures (GTCS) were evaluated. Analysis of intent-to-treat population was performed using Fisher's and Wilcoxon tests. Results: Thirty-five patients (23 F) with a mean age of 19 +/- 6 years were recruited. Twenty-seven had previously undergone one to five adequate trials of antiepileptic drugs. The median number of DwS/month was 12 +/- 8.2. Twenty-one patients experienced GTCS (median number/month: 1 +/- 0.2). Thirty-four subjects completed the trial. Levetiracetam was well tolerated (mean dose: 1985 mg/day). Responders were 28/35 (80%) patients, nine taking levetiracetam as monotherapy. Six patients were seizure-free, 15 had >= 75% and seven > 50% seizure reduction. GTCS remitted in 14 out of 21 (66.6%) patients. The number/month of DwS (median: 12 vs 5; p = 0.0001) and of GTCS (median: 1 vs 0; p = 0.0001) decreased compared to baseline period. Disappearance or clear reduction in paroxysmal abnormalities at eye closure occurred in 20 of the responders and photoparoxysmal response in 19. Mean follow-up was 23.9 +/- 18.5 months. Conclusion: Levetiracetam is effective and well tolerated in EMA. Placebo-controlled studies should confirm these findings

Seizures and EEG patterns in Pallister-Killian syndrome: 13 New Italian patients.

Background and objectives: PallistereKillian syndrome (PKS) is a rare genetic disorder caused by a tissue-limited mosaic supernumerary isochromosome 12p. Typical facial dysmorphisms, pigmentary abnormalities, and some major malformations are frequently present. Neurological manifestations include mental retardation, hypotonia, and seizures. Epilepsy incidence ranged from 39 to 59% in a previously reported series. No specific clinical and EEG phenotype has ever been reported to describe seizure features, electroclinical patterns, and response to therapy in PKS. Methods: This was a multicentre study conducted on 13 Italian children with PKS, as diagnosed by clinical phenotype and confirmed in cultured fibroblasts. All patients underwent several polygraphic video-EEG recordings and brain magnetic resonance imaging. Results and conclusions: All the patients presented with epilepsy and seizures that started at a mean age of 19 months. In six cases, epilepsy started with epileptic spasms (ES) combined with focal seizures in another case. In four cases, seizures were focal, and this was followed by ES in two patients. In only two cases, epilepsy started with myoclonic seizures, and spasms were never observed. The study provides further evidence that epilepsy is a part of the phenotype of PKS, although a specific clinical and EEG pattern could not be identified. Our cases show how ES with late- or first-year onset is the most common type of seizure. Despite a variable prognosis in terms of response to therapy, a significant proportion of patients achieved good seizure control