Correlation Effects on Transport Through Few-Electrons Systems

We study lateral tunneling through a quantum box including electron-electron interactions in the presence of a magnetic field which breaks single particle degeneracies. The conductance at zero temperature as a function of the Fermi energy in the leads consists of a set of peaks related to changing by one the electron occupancy in the box. We find that the position and heights of the peaks are controlled by many-body effects. We compute the conductance up to 8 electrons for several cases where correlation effects dominate. In the range of intermediate fields spin selection rules quench some peaks. At low and high fields the behavior of the conductance as a function of the number of electrons is very different due to big changes in the many-body ground state wavefunctions.Comment: 9 pages, 2 postscript figures, Latex 3.1

Expanding the phenotypic spectrum of lupus erythematosus in Aicardi-Goutie`res syndrome

Objective. Aicardi-Goutie`res syndrome (AGS) isan early-onset encephalopathy resembling congenitalviral infection that is characterized by basal gangliacalcifications, loss of white matter, cerebrospinal fluid(CSF) lymphocytosis, and elevated interferon- levels inthe CSF. Studies have shown that AGS is an autosomalrecessivedisease linked to mutations in 5 genes, encodingthe 3 -repair DNA exonuclease 1 (TREX1), the 3subunits of ribonuclease H2 (RNASEH2A–C), and sterilealpha motif domain and HD domain–containingprotein 1 (SAMHD1). In this study we further characterizedthe phenotypic spectrum of this disease.Methods. Clinical and laboratory data were obtainedfrom 26 patients fulfilling the clinical diagnosticcriteria for AGS. Genomic DNA was screened for mutationsin all 5 AGS genes by direct sequencing, and serawere analyzed for autoantibodies.Results. In 20 patients with AGS, 20 mutations,12 of which were novel, were identified in all 5 AGSgenes. Clinical and laboratory investigations revealed ahigh prevalence of features (some not previously describedin patients with AGS) that are commonly seen inpatients with systemic lupus erythematosus (SLE), suchas thrombocytopenia, leukocytopenia, antinuclear antibodies,erythematous lesions, oral ulcers, and arthritis,which were observed in 12 (60%) of 20 patients withAGS. Moreover, the coexistence of AGS and SLE, wasfor the first time, demonstrated in 2 patients withmolecularly proven AGS.Conclusion. These findings expand the phenotypicspectrum of lupus erythematosus in AGS andprovide further insight into its disease mechanisms by showing that activation of the innate immune system asa result of inherited defects in nucleic acid metabolismcould lead to systemic autoimmunity

Oesophageal atresia: prevalence, prenatal diagnosis and associated anomalies in 23 European regions

Objective To describe prevalence, prenatal diagnosis and epidemiological data on oesophageal atresia from 23 well-defined European regions and compare the prevalence between these regions. Design Population-based study using data from a large European database for surveillance of congenital anomalies (EUROCAT) for two decades (1987-2006). Settings Twenty-three participating registries based on multiple sources of information including information about live births, fetal deaths with gestational age &#8805;20 weeks and terminations of pregnancy. Patients 1222 cases of oesophageal atresia in a population of 5 019 804 births. Results The overall prevalence was 2.43 cases per 10 000 births (95% CI 2.30 to 2.57). There were regional differences in prevalence ranging from 1.27 to 4.55. Prenatal detection rates varied by registry from >50% of cases to <10% of cases. A total of 546 cases (44.7%) had an isolated oesophageal anomaly, 386 (31.6%) were multiple malformed and 290 (23.7%) had an association or a syndrome. There were 1084 live born cases (88.7%), 43 cases were fetal deaths and 95 cases were terminations of pregnancy. One-week survival for live births was 86.9% and 99.2% if the gestational age was &#8805;38 weeks and isolated oesophageal atresia was present. Males accounted for 57.3% of all cases and 38.5% of live born cases were born with gestational age <37 weeks. Conclusion There were regional differences in prevalence of oesophageal atresia in Europe. Half of all cases had associated anomalies. Prenatal detection rate increased from 26% to 36.5% over the two decades. Survival in infants with isolated oesophageal atresia born at term is hig

Split-spectrum amplitude-decorrelation angiography with optical coherence tomography

Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction. To overcome this limitation, we developed split-spectrum amplitude-decorrelation angiography (SSADA) to improve the signal-to-noise ratio (SNR) of flow detection. The full OCT spectrum was split into several narrower bands. Inter-B-scan decorrelation was computed using the spectral bands separately and then averaged. The SSADA algorithm was tested on in vivo images of the human macula and optic nerve head. It significantly improved both SNR for flow detection and connectivity of microvascular network when compared to other amplitude-decorrelation algorithms.National Institutes of Health (U.S.) (Grant R01 EY013516)National Institutes of Health (U.S.) (Grant R01-EY11289-26)United States. Air Force Office of Scientific Research (FA9550-10-1-0551

Properties of Graphene: A Theoretical Perspective

In this review, we provide an in-depth description of the physics of monolayer and bilayer graphene from a theorist's perspective. We discuss the physical properties of graphene in an external magnetic field, reflecting the chiral nature of the quasiparticles near the Dirac point with a Landau level at zero energy. We address the unique integer quantum Hall effects, the role of electron correlations, and the recent observation of the fractional quantum Hall effect in the monolayer graphene. The quantum Hall effect in bilayer graphene is fundamentally different from that of a monolayer, reflecting the unique band structure of this system. The theory of transport in the absence of an external magnetic field is discussed in detail, along with the role of disorder studied in various theoretical models. We highlight the differences and similarities between monolayer and bilayer graphene, and focus on thermodynamic properties such as the compressibility, the plasmon spectra, the weak localization correction, quantum Hall effect, and optical properties. Confinement of electrons in graphene is nontrivial due to Klein tunneling. We review various theoretical and experimental studies of quantum confined structures made from graphene. The band structure of graphene nanoribbons and the role of the sublattice symmetry, edge geometry and the size of the nanoribbon on the electronic and magnetic properties are very active areas of research, and a detailed review of these topics is presented. Also, the effects of substrate interactions, adsorbed atoms, lattice defects and doping on the band structure of finite-sized graphene systems are discussed. We also include a brief description of graphane -- gapped material obtained from graphene by attaching hydrogen atoms to each carbon atom in the lattice.Comment: 189 pages. submitted in Advances in Physic

Communications Biophysics

Contains reports on four research projects.National Institutes of Health (Grant 5 P01 NS13126-02)National Institutes of Health (Grant 5 K04 NS00113-03)National Institutes of Health (Grant 2 ROI NS11153-02A1)National Science Foundation (Grant BNS77-16861)National Institutes of Health (Grant 5 RO1 NS10916-03)National Institutes of Health (Fellowship 1 F32 NS05327)National Institutes of Health (Grant 5 ROI NS12846-02)National Institutes of Health (Fellowship 1 F32 NS05266)Edith E. Sturgis FoundationNational Institutes of Health (Grant 1 R01 NS11680-01)National Institutes of Health (Grant 2 RO1 NS11080-04)National Institutes of Health (Grant 5 T32 GIM107301-03)National Institutes of Health (Grant 5 TOI GM01555-10

Communications Biophysics

Contains reports on nine research projects split into four sections.National Institutes of Health (Grant 5 PO1 NS13126)National Institutes of Health (Grant 5 KO4 NS00113)National Institutes of Health (Training Grant 5 T32 NS07047)National Institutes of Health (Training Grant 1 T32 NS07099)National Science Foundation (Grant BNS77-16861)National Institutes of Health (Grant 5 ROI NS10916)National Institutes of Health (Grant 5 RO1 NS12846)National Science Foundation (Grant BNS77-21751)National Institutes of Health (Grant 1 RO1 NS14092)Edith E. Sturgis FoundationHealth Sciences FundNational Institutes of Health (Grant 2 R01 NS11680)National Institutes of Health (Fellowship 5 F32 NS05327)National Institutes of Health (Grant 2 ROI NS11080)National Institutes of Health (Training Grant 5 T32 GM07301

Communications Biophysics

Contains reports on nine research projects split into four sections.National Institutes of Health (Grant 5 P01 NS13126)National Institutes of Health (Grant 5 K04 NS00113)National Institutes of Health (Training Grant 5 T32 NS07047)National Institutes of Health (Grant 5 ROl NS11153-03)National Institutes of Health (Fellowship 1 T32 NS07099-01)National Science Foundation (Grant BNS77-16861)National Institutes of Health (Grant 5 ROl NS10916)National Institutes of Health (Grant 5 ROl NS12846)National Science Foundation (Grant BNS77-21751)National Institutes of Health (Grant 1 RO1 NS14092)Health Sciences FundNational Institutes of Health (Grant 2 R01 NS11680)National Institutes of Health (Grant 2 RO1 NS11080)National Institutes of Health (Training Grant 5 T32 GM07301