Excitonic Effects in Quantum Wires

We review the effects of Coulomb correlation on the linear and non-linear optical properties of semiconductor quantum wires, with emphasis on recent results for the bound excitonic states. Our theoretical approach is based on generalized semiconductor Bloch equations, and allows full three-dimensional multisubband description of electron-hole correlation for arbitrary confinement profiles. In particular, we consider V- and T-shaped structures for which significant experimental advances were obtained recently. Above band gap, a very general result obtained by this approach is that electron-hole Coulomb correlation removes the inverse-square-root single-particle singularity in the optical spectra at band edge, in agreement with previous reports from purely one-dimensional models. Strong correlation effects on transitions in the continuum are found to persist also at high densities of photoexcited carriers. Below bandgap, we find that the same potential- (Coulomb) to kinetic-energy ratio holds for quite different wire cross sections and compositions. As a consequence, we identify a shape- and barrier-independent parameter that governs a universal scaling law for exciton binding energy with size. Previous indications that the shape of the wire cross-section may have important effects on exciton binding are discussed in the light of the present results.Comment: Proc. OECS-5 Conference, G\"ottingen, 1997 (To appear in Phys. Stat. Sol. (b)

Lymphectomy in the treatment of thyroid cancer in adults and children.

Thyroid carcinoma is thè most frequent endocrine malignancy in Italy and differs in naturai history according to histological type and age of patients. Lymph node metastases are more frequently seen in young patients with papillary carcinoma. However, many clinical series suggested that although thè incidence of lymph node invasion in high-risk patients (over-50s) is slightiy lower than in low-risk patients, thè locai recurrence rate is higher than in thè former. From thè results of our experience, confirmed by other authors, we retain total thyroidectomy with lymphectomy of thè centrai compartment as thè procedure of choice in thè treatment of well-differentiated thyroid carcinoma in thè under-50s. In thè over-50s, functional bilateral lymphectomy improves survival and should be considered mandatory, just as for medullary carcinoma. On thè contrary, thè prognosis of anaplastic carcinoma is not improved by lymphectomy

The biofragmentable anastomosis ring in elective colon resections.

Methods. Sixty-eight patients underwent elective colon resection and ìntraperitoneal anastomosis wìth thè biofragmentable anastomosis ring (BAR). Results. Anastomotic dehiscence occurred in 3 patients (4.4%). Two of them had an end-to-end ileocolostomy using a 31 mm BAR. The anastomosis failure was due to ischaemic lesion of thè small bowel dose to thè ileocolostomy, probably caused by a mismatch between thè size of small bowel and that of thè BAR. Another patient experienced anastomosis dehiscence probably due to a faecal impaction into thè BAR. Forty-eight patients (70.5%) experienced troublesome constipation and evacuated after thè sixth postoperative day. A bowel obstruction proximal to thè BAR was documented in 4 cases who have been treated conservatively. Condmions. The low rate of major complications justify thè use of thè BAR in elective colon surgery, but thè surgeon must be aware of tedious postoperative obstructive episodes frequently encountered in this series

Connes distance by examples: Homothetic spectral metric spaces

We study metric properties stemming from the Connes spectral distance on three types of non compact noncommutative spaces which have received attention recently from various viewpoints in the physics literature. These are the noncommutative Moyal plane, a family of harmonic Moyal spectral triples for which the Dirac operator squares to the harmonic oscillator Hamiltonian and a family of spectral triples with Dirac operator related to the Landau operator. We show that these triples are homothetic spectral metric spaces, having an infinite number of distinct pathwise connected components. The homothetic factors linking the distances are related to determinants of effective Clifford metrics. We obtain as a by product new examples of explicit spectral distance formulas. The results are discussed.Comment: 23 pages. Misprints corrected, references updated, one remark added at the end of the section 3. To appear in Review in Mathematical Physic

Anterior Segment-Optical Coherence Tomography features in Blau syndrome.

Blau syndrome (BS) is a rare granulomatous auto-inflammatory disease, characterized by the classic clinical triad of joints, skin and ocular involvements. Ocular manifestation usually consists in a bilateral insidious chronic anterior uveitis with a potential evolution to panuveitis. We describe the case of two siblings, an 8-years old female and a 5-years old male, with a diagnosis of BS, evaluated by Anterior Segment-Optical Coherence Tomography (AS-OCT). In the female patient, slit-lamp examination revealed bilateral anterior granulomatous uveitis and inflammatory sequelae. AS-OCT revealed high intensity reflective layers in the anterior cornea, hyperreflective dots both in the aqueous humor and in the posterior corneal surface. In the male, no signs of inflammation were detected both on slit-lamp examination and AS-OCT scans. AS-OCT is a valuable, non-invasive tool that could improve the diagnosis of ocular involvement, better characterize and follow-up corneal alterations and anterior segment features in pediatric patients with BS

Genomics knowledge and attitudes among European public health professionals. Results of a cross-sectional survey

Background The international public health (PH) community is debating the opportunity to incorporate genomic technologies into PH practice. A survey was conducted to assess attitudes of the European Public Health Association (EUPHA) members towards their role in the implementation of public health genomics (PHG), and their knowledge and attitudes towards genetic testing and the delivery of genetic services. Methods EUPHA members were invited via monthly newsletter and e-mail to take part in an online survey from February 2017 to January 2018. A descriptive analysis of knowledge and attitudes was conducted, along with a univariate and multivariate analysis of their determinants. Results Five hundred and two people completed the questionnaire, 17.9% were involved in PHG activities. Only 28.9% correctly identified all medical conditions for which there is (or not) evidence for implementing genetic testing; over 60% thought that investing in genomics may divert economic resources from social and environmental determinants of health. The majority agreed that PH professionals may play different roles in incorporating genomics into their activities. Better knowledge was associated with positive attitudes towards the use of genetic testing and the delivery of genetic services in PH (OR = 1.48; 95% CI 1.01–2.18). Conclusions Our study revealed quite positive attitudes, but also a need to increase awareness on genomics among European PH professionals. Those directly involved in PHG activities tend to have a more positive attitude and better knowledge; however, gaps are also evident in this group, suggesting the need to harmonize practice and encourage greater exchange of knowledge among professionals

Effect of lifestyle changes on erectile dysfunction in obese men: a randomized controlled trial

Context: Healthy lifestyle factors are associated with maintenance of erectile function in men. Objective: To determine the effect of weight loss and increased physical activity on erectile and endothelial functions in obese men. Design, Setting, and Patients: Randomized, single-blind trial of 110 obese men (body mass index ≥30) aged 35 to 55 years, without diabetes, hypertension, or hyperlipidemia, who had erectile dysfunction that was determined by having a score of 21 or less on the International Index of Erectile Function (IIEF). The study was conducted from October 2000 to October 2003 at a university hospital in Italy. Interventions: The 55 men randomly assigned to the intervention group received detailed advice about how to achieve a loss of 10% or more in their total body weight by reducing caloric intake and increasing their level of physical activity. Men in the control group (n=55) were given general information about healthy food choices and exercise. Main Outcomes Measures: Erectile function score, levels of cholesterol and tryglycerides, circulating levels of interleukin 6, interleukin 8, and C-reactive protein, and endothelial function as assessed by vascular responses to L-arginine. Results: After 2 years, body mass index decreased more in the intervention group (from a mean [SD] of 36.9 [2.5] to 31.2 [2.1]) than in the control group (from 36.4 [2.3] to 35.7 [2.5]) (P<.001), as did serum concentrations of interleukin 6 (P=.03), and C-reactive protein (P=.02). The mean (SD) level of physical activity increased more in the intervention group (from 48 [10] to 195 [36] min/wk; P<.001) than in the control group (from 51 [9] to 84 [28] min/wk; P<.001). The mean (SD) IIEF score improved in the intervention group (from 13.9 [4.0] to 17 [5]; P<.001), but remained stable in the control group (from 13.5 [4.0] to 13.6 [4.1]; P=.89). Seventeen men in the intervention group and 3 in the control group (P=.001) reported an IIEF score of 22 or higher. In multivariate analyses, changes in body mass index (P=.02), physical activity (P=.02), and C-reactive protein (P=.03) were independently associated with changes in IIEF score. Conclusion: Lifestyle changes are associated with improvement in sexual function in about one third of obese men with erectile dysfunction at baseline

An equivariant pullback structure of trimmable graph C^*-algebras

To unravel the structure of fundamental examples studied in noncommutative topology, we prove that the graph C*-algebra C*(E) of a trimmable graph E is U(1)-equivariantly iso-morphic to a pullback C *-algebra of a subgraph C *-algebra C*(E'') and the C *-algebra of func-tions on a circle tensored with another subgraph C*-algebra C*(E'). This allows us to approach the structure and K-theory of the fixed-point subalgebra C*(E)U .1/ through the (typically simpler) C *-algebras C*(E'), C*(E'') and C*(E'')U.1/. As examples of trimmable graphs, we consider one-loop extensions of the standard graphs encoding respectively the Cuntz algebra O2 and the Toeplitz algebra T . Then we analyze equivariant pullback structures of trimmable graphs yielding the C*-algebras of the Vaksman-Soibelman quantum sphere S2n+1 q and the quantum lens space L3 q(l;1, l), respectively.Analysis and Stochastic