588 research outputs found
Monte Carlo study of coaxially gated CNTFETs: capacitive effects and dynamic performance
Carbon Nanotube (CNT) appears as a promising candidate to shrink field-effect
transistors (FET) to the nanometer scale. Extensive experimental works have
been performed recently to develop the appropriate technology and to explore DC
characteristics of carbon nanotube field effect transistor (CNTFET). In this
work, we present results of Monte Carlo simulation of a coaxially gated CNTFET
including electron-phonon scattering. Our purpose is to present the intrinsic
transport properties of such material through the evaluation of electron
mean-free-path. To highlight the potential of high performance level of CNTFET,
we then perform a study of DC characteristics and of the impact of capacitive
effects. Finally, we compare the performance of CNTFET with that of Si nanowire
MOSFET.Comment: 15 pages, 14 figures, final version to be published in C. R. Acad.
Sci. Pari
A grid of polarization models for Rayleigh scattering planetary atmospheres
We investigate the intensity and polarization of reflected light from
planetary atmospheres. We present a large grid of Monte Carlo simulations for
planets with Rayleigh scattering atmospheres. We discuss the disk-integrated
polarization for phase angles typical of extrasolar planet observations and for
the limb polarization effect observable for solar system objects near
opposition. The main parameters investigated are single scattering albedo,
optical depth of the scattering layer, and albedo of an underlying Lambert
surface for a homogeneous Rayleigh scattering atmosphere. We also investigate
atmospheres with isotropic scattering and forward scattering aerosol particles,
as well as models with two scattering layers.
The model grid provides a tool for extracting quantitative results from
polarimetric measurements of planetary atmospheres from solar system planets
and extrasolar planets, in particular on the scattering properties and
stratification of particles in the highest atmosphere layers.
Spectropolarimetry of solar system planets offers complementary information to
spectroscopy and polarization flux colors can be used for a first
characterization of exoplanet atmospheres. From limb polarization measurements,
one can set constraints on the polarization at large phase angles.Comment: 19 pages, 21 figures. Minor changes. Published in Astronomy and
Astrophysic
Current management of primary mitochondrial disorders in EU countries: the European Reference Networks survey
Background and purpose: Primary mitochondrial diseases (PMDs) are rare diseases for which diagnosis is challenging, and management and training programs are not well defined in Europe. To capture and assess care needs, five different European Reference Networks have conducted an exploratory survey. Methods: The survey covering multiple topics relating to PMDs was sent to all ERNs healthcare providers (HCPs) in Europe. Results: We have collected answers from 220 members based in 24/27 European member states and seven non-European member states. Even though most of the responders are aware of neurogenetic diseases, difficulties arise in the ability to deliver comprehensive genetic testing. While single gene analysis is widely available in Europe, whole exome and genome sequencing are not easily accessible, with considerable variation between countries and average waiting time for results frequently above 6Â months. Only 12.7% of responders were happy with the ICD-10 codes for classifying patients with PMDs discharged from the hospital, and more than 70% of them consider that PMDs deserve specific ICD codes to improve clinical management, including tailored healthcare, and for reimbursement reasons. Finally, 90% of responders declared that there is a need for further education and training in these diseases. Conclusions: This survey provides information on the current difficulties in the care of PMDs in Europe. We believe that the results of this survey are important to help rare disease stakeholders in European countries identify key care and research priorities
Prenatal diagnosis of focal dermal hypoplasia: Report of three fetuses and review of the literature
Focal dermal hypoplasia (FDH) is a rare syndrome characterized by pleiotropic features knowing to involve mostly skin and limbs. Although FDH has been described in children and adults, the cardinal signs of the fetal phenotype are not straightforward impacting the quality of the prenatal diagnosis. We describe in depth the ultrasound, radiological, macroscopical, and histological phenotype of three female fetuses with a severe form of FDH, propose a review of the literature and an attempt to delineate minimal and cardinal signs for FDH diagnosis. This report confirms the variability of FDH phenotype, highlights unreported FDH features, and allows delineating evocative clinical associations for prenatal diagnosis, namely intrauterine growth retardation, limbs malformations, anterior wall/diaphragm defects, and eye anomalies. © 2016 Wiley Periodicals, Inc
Dermatologic findings in 16 patients with Cockayne syndrome and cerebro-oculo-facial-skeletal syndrome
IMPORTANCE: Cockayne syndrome (CS) and cerebro-oculo-facial-skeletal (COFS) syndrome are autosomal recessive diseases that belong to the family of nucleotide excision repair disorders. Our aim was to describe the cutaneous phenotype of patients with these rare diseases. OBSERVATIONS: A systematic dermatologic examination of 16 patients included in a European study of CS was performed. The patients were aged 1 to 28 years. Six patients (38%) had mutations in the Cockayne syndrome A (CSA) gene, and the remaining had Cockayne syndrome B (CSB) gene mutations. Fourteen patients were classified clinically as having CS and 2 as having COFS syndrome. Photosensitivity was present in 75% of the patients and was characterized by sunburn after brief sun exposure. Six patients developed symptoms after short sun exposure through a windshield. Six patients had pigmented macules on sun-exposed skin, but none developed a skin neoplasm. Twelve patients (75%) displayed cyanotic acral edema of the extremities. Eight patients had nail dystrophies and 7 had hair anomalies. CONCLUSIONS AND RELEVANCE: The dermatologic findings of 16 cases of CS and COFS syndrome highlight the high prevalence of photosensitivity and hair and nail disorders. Cyanotic acral edema was present in 75% of our patients, a finding not previously reported in CS
European Reference Networks: challenges and opportunities
European Reference Networks (ERNs) were founded on the principle that many rare disease (RD) issues are pan-European and any single Member State cannot solve them alone. In 2021, ERNs are already in the deployment stage; however, their day-to-day functioning and realization of their potential are still severely hampered by many challenges, including issues in governance and regulation, lack of legal status, insufficient and unsustainable funding, lack of ERN integration into national systems, endangered collaboration with UK RD experts due to Brexit, insufficient exploitation of ERN potential in RD research, underappreciation of highly qualified human resources, problems with the involvement of patient representatives, and still unclear place of ERNs in the overall European RD and digital ecosystem. Bold and innovative solutions that must be taken to solve these challenges inevitably involve pan-European collaboration across several sectors and among multistakeholder RD communities and in many cases crucially rely on the constructive dialogue and coherent, united decisions of national and European authorities that are based on common EU values. Importantly, unresolved challenges may have a strong impact on the further sustainability of ERNs and their ability to realize full potential in addressing huge unmet needs of RD patients and their families.Diabetes mellitus: pathophysiological changes and therap
FOXE3 mutations: genotype-phenotype correlations
Microphthalmia and anophthalmia (MA) are severe developmental eye anomalies, many of
which are likely to have an underlying genetic cause. More than 30 genes have been described, each of which is responsible for a small percentage of these anomalies. Amongst these, is the FOXE3 gene, which was initially described in individuals with dominantly inherited anterior segment dysgenesis and, subsequently, associated with recessively inherited primary aphakia, sclerocornea and microphthalmia. In this work, we describe 8 individuals presenting with a MA phenotype. Among them, 7 are carrying biallelic recessive FOXE3 mutations and 2 of these have novel mutations: p.(Ala78Thr) and p.(Arg104Cys). The last of our patients is carrying in the heterozygous state the recessive p.(Arg90Leu) mutation in the FOXE3 gene. To further understand FOXE3 involvement in this wide spectrum of ocular anomalies with two different patterns of inheritance, we reviewed all individuals with ocular abnormalities described in the literature for which a FOXE3 mutation was identified. This review demonstrates that correlations exist between the mutation type, mode of inheritance and the phenotype severity. Furthermore, understanding the genetic basis of these conditions will contribute to overall understanding of eye development, improve the quality of care, genetic counseling and, in future, gene based therapies
Expanding phenotype of hereditary fibrosing poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis caused by FAM111B mutations: Report of an additional family raising the question of cancer predisposition and a short review of early-onset poikiloderma.
journal article2017 Mar2017 03 19importedHereditary fibrosing poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis (POIKTMP [MIM#615704]) is an extremely rare syndromic form of autosomal dominant poikiloderma. This genetic disorder was first identified in a South African family in 2006.1 To date, 3 families and 9 independent sporadic cases have been reported.2-4 Here we report an additional family of POIKTMP and expand the clinical spectrum. We describe, for the first time to our knowledge, a pancreatic cancer in the clinical course in 1 patient
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