Size quantization effects in thin film Casimir interaction

We investigate the role of size quantization in the vacuum force between metallic films of nanometric thickness. The force is calculated by the Lifshitz formula with the film dielectric tensor derived from the one-electron energies and wavefunctions under the assumption of a constant potential inside the film and a uniform distribution of the positive ion charge. The results show that quantization effects tend to reduce the force with respect to the continuum plasma model. The reduction is more significant at low electron densities and for film size of the order of few nanometers and persists for separation distances up to 10 nm. Comparison with previous work indicates that the softening of the boundary potential is important in determining the amount of the reduction. The calculations are extended to treat Drude intraband absorption. It is shown that the inclusion of relaxation time enhances the size quantization effects in the force calculations

Loss of heterozygosity on chromosome 16p13.3 in hamartomas from tuberous sclerosis patients

Tuberous sclerosis (TSC) is an autosomal dominant condition with characteristic skin lesions, mental handicap, seizures and the development of hamartomas in the brain, heart, kidneys and other organs. Linkage studies have shown locus heterogeneity with a TSC gene mapped to chromosome 9q34 and a second, recently identified on 16p13.3. We have analysed DNA markers in eight hamartomas and one tumour from TSC patients and found allele loss on 16p13.3 in three angiomyolipomas, one cardiac rhabdomyoma, one cortical tuber and one giant cell astrocytoma. We suggest that the TSC gene on 16p13.3 functions like a tumour suppressor gene, in accordance with Knudsen's hypothesis

Fatal glioblastoma multiforme in a patient with neurofibromatosis type I: the dilemma of systematic medical follow-up.

INTRODUCTION: Neurofibromatosis type I (NF1) is one of the most prevalent genetic diseases of the nervous system. Although the majority of NF1 patients are only mildly affected, the risk of developing malignancies is significantly increased in this population. CASE REPORT: Here, we present a 9-year-old girl with clinical stigmata of NF1 and a rapidly evolving glioblastoma multiforme. Molecular genetic analysis uncovered a novel missense mutation in Exon 32 of the NF1 gene [c.6032C>A(p.Ala2011Glu)]. DISCUSSION: The girl's death 3 days after diagnosis of the brain tumor exemplifies that NF1 still is a life-threatening disease despite its generally benign course in most patients. However, it remains questionable if a fatal course as reported here can be prevented by routine MRI screening

Electron localization in (7x7) reconstructed and hydrogen- covered Si(111) surfaces as seen by NMR on adsorbed Li

The observation of "Korringa-like" nuclear-spin-lattice relaxation of Li-8 probe atoms, adsorbed at extremely low coverages on the Si(111)-(7x7) surface (10(-4) ML and below) points to the existence of a correlated two-dimensional electron gas. The observed high relaxation rates as compared to adsorption of Li-8 on metals are in accordance with an enhanced electron localization in the adatom dangling bonds. For Li-8 adsorbed on semiconducting hydrogen covered Si(111) surfaces (now at coverages around 10(-3) ML) "Korringa-like" spin- lattice relaxation is also observed, quite surprisingly. Independent of the preparation of the hydrogen coverage, i.e., in vacuum or wet chemically terminated, the relaxation rates are moreover all of the same size. This points to a narrow band at the Fermi energy generated by the adsorbed Li itself. Quantitative ab initio all-electron density-functional calculations for Li coverage as low as 0.04 on the perfectly hydrogen-terminated Si(111) surface together with a qualitative reasoning following Mott's arguments on semiconductor-metal transitions support this view

Am J Med Genet A

We report on a 25-year-old woman with pronounced generalized lipodystrophy and a progeroid aspect since birth, who also had Marfan syndrome (MFS; fulfilling the Ghent criteria) with mild skeletal features, dilated aortic bulb, dural ectasia, bilateral subluxation of the lens, and severe myopia in addition to the severe generalized lipodystrophy. She lacked insulin resistance, hypertriglyceridemia, hepatic steatosis, and diabetes. Mutation analysis in the gene encoding fibrillin 1 (FBN1) revealed a novel de novo heterozygous deletion, c.8155_8156del2 in exon 64. The severe generalized lipodystrophy in this patient with progeroid features has not previously been described in other patients with MFS and FBN1 mutations. We did not find a mutation in genes known to be associated with congenital lipodystrophy (APGAT2, BSCL2, CAV1, PTRF-CAVIN, PPARG, LMNB2) or with Hutchinson-Gilford progeria (ZMPSTE24, LMNA/C). Other progeria syndromes were considered unlikely because premature greying, hypogonadism, and scleroderma-like skin disease were not present. Our patient shows striking similarity to two patients who have been published in this journal by O'Neill et al. [O'Neill et al. (2007); Am J Med Genet Part A 143A:1421-1430] with the diagnosis of neonatal progeroid syndrome (NPS). This condition also known as Wiedemann-Rautenstrauch syndrome is a rare disorder characterized by accelerated aging and lipodystrophy from birth, poor postnatal weight gain, and characteristic facial features. The course is usually progressive with early lethality. However this entity seems heterogeneous. We suggest that our patient and the two similar cases described before represent a new entity, a subgroup of MFS with overlapping features to NPS syndrome