Quantum cascade lasers monolithically integrated on germanium.

Silicon (Si) photonics can have a major impact on the development of mid-IR photonics by leveraging on the reliable and high-volume fabrication technologies already developed for microelectronic integrated circuits. Germanium (Ge), already used in Si photonics, is a prime candidate to extend the operating wavelength of Group IV-based photonic integrated circuits beyond 8 µm, and potentially up to 15 µm. High performance quantum cascade lasers (QCLs) and interband cascade lasers grown on Si have been demonstrated, whereas no QCLs monolithically integrated on Ge have been reported yet. In this work, we present InAs-based QCLs directly grown on Ge by molecular beam epitaxy. The lasers emitting near 14 µm exhibited threshold current densities as low as 0.8-0.85 kA/cm2 at room temperature.

[Prevalence of vitamin D deficiency in children aged 5-10 years in western Brittany]. / Prévalence du déficit en vitamine D chez les enfants âgés de 5 à 10ans en Bretagne Occidentale.

UNLABELLED: French guidelines do not recommend systematic supplementation of vitamin D in children aged 5-10 years old owing to the lack of data on vitamin D status in this age group. Our objective was to assess the prevalence of vitamin D deficiency in these children. METHODOLOGY: Single-center, prospective, epidemiological study including 358 children aged 0-15 years. The endpoint was the concentration of vitamin D. RESULTS: In all, 316 children were divided into four groups according to age: 0-18 months (n=113); 18 months to 5 years (n=103); 5-10 years (n=62); and 10-15 years (n=38). The median concentration of vitamin D decreased with age (P<0.001): 90.2 nmol/L in the group aged 0-18 months; 56.7 nmol/L in the group aged 18 months to 5 years; 49.05 nmol/L in the group aged 5-10 years; and 42.45 nmol/L in the group aged 10-15 years. This corresponds to an increase in the prevalence of vitamin D deficiency in children aged 5-10 years (51.6% vs. 8.8% in the group aged 0-18 months, P<0.001). For children aged 5-10 years, the prevalence of deficiency was greater in the non-supplementation group (75%) compared with the supplementation group (13%; P<0.001). CONCLUSION: This study demonstrates the high prevalence of vitamin D deficiency in children aged 5-10 years and the relationship between supplementation and vitamin D status. It provides an argument in favor of supplementation in children aged 5-10 years in this region and a reconsideration of the French recommendations.

High temperature operation of far infrared (λ ≈20 µm) InAs/AlSb quantum cascade lasers with dielectric waveguide.

We demonstrate the high temperature operation, up to 80°C, of quantum cascade lasers emitting at a wavelength of 20 µm. The lasers are based on the InAs/AlSb materials and take benefit of a low loss plasmon-enhanced dielectric waveguide. The waveguide consists of doped InAs cladding layers and low-doped InAs spacers. For 2.9-mm-long devices, the threshold current density is 4.3 kA/cm2 and the measured peak output power is 7 mW at room temperature. The cavity length dependence of the threshold currents also indicates that very large optical gain is achieved and effectively overcome the strong free carrier absorption.

Characterization and prevalence of severe primary IGF1 deficiency in a large cohort of French children with short stature.

OBJECTIVE: The prevalence of severe primary IGF1 deficiency (IGFD) is unclear. IGFD must be identified promptly as treatment with recombinant human IGF1 (rhIGF1) is now available. Our objective was to characterize and assess the prevalence of severe primary IGFD in a large cohort of patients evaluated for short stature at a pediatric endocrinology unit in France. DESIGN: Observational study in a prospective cohort. METHODS: Consecutive patients referred to our unit between 2004 and 2009 for suspected slow statural growth were included. Patients were classified into eight etiological categories. IGFD was defined by height ≤-3 SDS, serum IGF1 levels <2.5th percentile, GH sufficiency, and absence of causes of secondary IGFD. RESULTS: Out of 2546 patients included, 337 (13.5%) were born small for gestational age and 424 (16.9%) had idiopathic short stature. In these two categories, we identified 30 patients who met our criterion for IGFD (30/2546, 1.2%). In these 30 patients, we assessed the response to IGF1 generation test, time course of IGF1 levels, and efficiency of GH replacement therapy. The results indicated that only four of the 30 children were definite or possible candidates for rhIGF1 replacement therapy. CONCLUSION: The prevalence of severe primary IGFD defined using the standard criterion for rhIGF1 treatment was 1.2%, and only 0.2% of patients were eligible for rhIGF1 therapy.

Unexpected high frequency of skeletal dysplasia in idiopathic short stature and small for gestational age patients.

OBJECTIVE: To assess the prevalence of skeletal dysplasias (SDs) in patients with idiopathic short stature (ISS) or small for gestational age (SGA) status. SETTING: Rare Endocrine/Growth Diseases Center in Paris, France. DESIGN: A prospective study on consecutive patients with ISS and SGA enrolled from 2004 to 2009. METHOD: We used a standardized workup to classify patients into well-established diagnostic categories. Of 713 patients with ISS (n=417) or SGA status (n=296), 50.9% underwent a skeletal survey. We chose patients labeled normal or with a prepubertal slowdown of growth as a comparison group. RESULTS: Diagnoses were ISS (16.9%), SGA (13.5%), normal growth (24.5%), transient growth rate slowing (17.3%), endocrine dysfunction (12%), genetic syndrome (8.9%), chronic disease (5.1%), and known SD (1.8%). SD was found in 20.9% of SGA and 21.8% ISS patients and in only 13.2% in our comparison group. SD prevalence was significantly higher in the ISS group than in the comparison group, especially (50%) for patients having at least one parent whose height was <-2 SDS. Dyschondrosteosis and hypochondroplasia were the most frequently identified SD, and genetic anomaly was found in 61.5 and 30% respectively. Subtle SD was found equally in the three groups and require long-term growth follow-up to evaluate the impact on final height. CONCLUSION: SD may explain more than 20% of cases of growth retardation ascribed to ISS or SGA, and this proportion is higher when parental height is <-2 SDS. A skeletal survey should be obtained in patients with delayed growth in a context of ISS or SGA.

[Centralized preparation in the pharmacy of dilute solutions of ganciclovir: (Cymevan): work load change and economic potential]. / Préparation centralisée en pharmacie des solutions diluées de ganciclovir (Cymévan): prévision de la charge de travail et de l'économie potentielle.

The production of ganciclovir doses by a hospital pharmacy having the necessary facilities to reconstitute anticancer drugs would be of the utmost relevance regarding both protection of the nursing staff and therapeutic safety. As this activity is also economically worthwhile a large number of our colleagues would like to implement it. The aim of this work has was to take advantage of a 40 weeks production of ganciclovir dose by the pharmacy at Rangueil hospital in Toulouse so as to answer some of the questions raised by such a project. The savings achieved by the team at Brabois hospital in Vandoeuvre les Nancy could therefore be validated. They are expressed in fraction of flask per dose produced (0,265). Applied to the number of doses that we delivered over a 40 week period, this coefficient enabled us to estimate from the only datum which is initially available to us, namely the number of flasks used, the extra work load and the savings that could be made: given steady activity, the number of doses the pharmacy will have to prepare is equal to the number of flasks multiplied by 1.418 and, provided one opts for a production process mostly in batches, the savings will be equivalent to 37.5% of the flasks.