20 research outputs found
Resonant scattering on impurities in the Quantum Hall Effect
We develop a new approach to carrier transport between the edge states via
resonant scattering on impurities, which is applicable both for short and long
range impurities. A detailed analysis of resonant scattering on a single
impurity is performed. The results are used for study of the inter-edge
transport by multiple resonant hopping via different impurities' sites. It is
shown that the total conductance can be found from an effective Schroedinger
equation with constant diagonal matrix elements in the Hamiltonian, where the
complex non-diagonal matrix elements are the amplitudes of a carrier hopping
between different impurities. It is explicitly demonstrated how the complex
phase leads to Aharonov-Bohm oscillations in the total conductance. Neglecting
the contribution of self-crossing resonant-percolation trajectories, one finds
that the inter-edge carrier transport is similar to propagation in
one-dimensional system with off-diagonal disorder. We demonstrated that each
Landau band has an extended state , while all other states are
localized. The localization length behaves as .Comment: RevTex 41 pages; 3 Postscript figure on request; Final version
accepted for publication in Phys. Rev. B. A new section added contained a
comparison with other method
Inhibiting decoherence via ancilla processes
General conditions are derived for preventing the decoherence of a single
two-state quantum system (qubit) in a thermal bath. The employed auxiliary
systems required for this purpose are merely assumed to be weak for the general
condition while various examples such as extra qubits and extra classical
fields are studied for applications in quantum information processing. The
general condition is confirmed with well known approaches towards inhibiting
decoherence. A novel approach for decoherence-free quantum memories and quantum
operations is presented by placing the qubit into the center of a sphere with
extra qubits on its surface.Comment: pages 8, Revtex
Importance of mRNA secondary structural elements for the expression of influenza virus genes.
Development of novel vaccines and therapeutics often requires efficient expression of recombinant viral proteins. Here we show that mutations in essential functional regions of conserved influenza proteins NP and NS1, lead to reduced expression of these genes in vitro. According to in silico analysis, these mRNA regions possess distinct secondary structures sensitive to mutations. We identified a novel structural feature within a region in NS1 mRNA that encodes amino acids essential for NS1 function. Mutations altering this mRNA element lead to significantly reduced protein expression. Conversely, expression was not affected by mutations resulting in amino acid substitutions, when they were designed to preserve this secondary RNA structural element. Furthermore, altering this structure significantly reduced RNA transcription without affecting mRNA stability. Therefore, distinct internal secondary structures of viral mRNA may be important for viral gene expression. If such elements encode amino acids essential for the protein function, then early selection against mutations in this region will be beneficial for the virus. This might point at yet another mechanism of viral evolution, especially for RNA viruses. Finally, introducing mutations into viral genes while preserving their secondary RNA structure, suggests a new method for the generation of efficiently expressed recombinants of viral proteins
Influence of heart rate increase on uncorrected pre-ejection period/left ventricular ejection time (PEP/LVET) ratio in normal individuals.
Effects of propranolol on left ventricular wall movement in patients with ischaemic heart disease.
Systolic time intervals: a review of the method in the non-invasive investigation of cardiac function in health, disease and clinical pharmacology.
To Judge a Book by its Cover: Religio-Cultural Myth on the Cover of Iranian War Literature
Pregnancies conceived using assisted reproductive technologies (ART) have low levels of pregnancy-associated plasma protein-A (PAPP-A) leading to a high rate of false-positive results in first trimester screening for Down syndrome
Cardiovascular disease and inflammation
Polycystic ovary syndrome (PCOS) is not only a reproductive disorder, but also a complex, multifaceted, endocrine disease with several associated health complications. In fact, multiple lines suggest an increased cardiovascular risk and cardiovascular disease characterized by an impairment of cardiac structure and function, endothelial dysfunction, lipid abnormalities, and low-grade chronic inflammation. The increased prevalence of low-grade chronic inflammation in women with PCOS represents an emerging novel mechanism for cardiovascular disease in these women. All these features are likely linked to the insulin-resistance often present in women with PCOS. Cardiovascular disease and inflammation represent important long-term sequelae of PCOS that warrant further in-depth investigation
Extensive identification of genes involved in congenital and structural heart disorders and cardiomyopathy.
Clinical presentation of congenital heart disease is heterogeneous,
making identification of the disease-causing genes and their genetic
pathways and mechanisms of action challenging. By using in vivo
electrocardiography, transthoracic echocardiography and microcomputed
tomography imaging to screen 3,894 single-gene-null mouse lines for
structural and functional cardiac abnormalities, here we identify 705
lines with cardiac arrhythmia, myocardial hypertrophy and/or ventricular
dilation. Among these 705 genes, 486 have not been previously
associated with cardiac dysfunction in humans, and some of them
represent variants of unknown relevance (VUR). Mice with mutations in Casz1, Dnajc18, Pde4dip, Rnf38 or Tmem161b
genes show developmental cardiac structural abnormalities, with their
human orthologs being categorized as VUR. Using UK Biobank data, we
validate the importance of the DNAJC18 gene for cardiac
homeostasis by showing that its loss of function is associated with
altered left ventricular systolic function. Our results identify
hundreds of previously unappreciated genes with potential function in
congenital heart disease and suggest causal function of five VUR in
congenital heart disease