547 research outputs found
Ultrafast spatio-temporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases
We present a combined theoretical and experimental study of spatio-temporal
propagation effects in terahertz (THz) generation in gases using two-color
ionizing laser pulses. The observed strong broadening of the THz spectra with
increasing gas pressure reveals the prominent role of spatio-temporal reshaping
and of a plasma-induced blue-shift of the pump pulses in the generation
process. Results obtained from (3+1)-dimensional simulations are in good
agreement with experimental findings and clarify the mechanisms responsible for
THz emission
Quantum-mechanical wavepacket transport in quantum cascade laser structures
We present a viewpoint of the transport process in quantum cascade laser
structures in which spatial transport of charge through the structure is a
property of coherent quantum-mechanical wavefunctions. In contrast, scattering
processes redistribute particles in energy and momentum but do not directly
cause spatial motion of charge.Comment: 6 pages, 5 figures included in tex, to appear in Physical Review
Full-gene haplotypes refine CYP2D6 metabolizer phenotype inferences
CYP2D6 is a critical pharmacogenetic target, and polymorphisms in the gene region are commonly used to infer enzyme activity score and predict resulting metabolizer phenotype: poor, intermediate, extensive/normal, or ultrarapid which can be useful in determining cause and/or manner of death in some autopsies. Current genotyping approaches are incapable of identifying novel and/or rare variants, so CYP2D6 star allele definitions are limited to polymorphisms known a priori. While useful for most predictions, recent studies using massively parallel sequencing data have identified additional polymorphisms in CYP2D6 that are predicted to alter enzyme function but are not considered in current star allele nomenclature. The 1000 Genomes Project data were used to produce full-gene haplotypes, describe their distribution in super-populations, and predict enzyme activity scores. Full-gene haplotypes generated lower activity scores than current approaches due to inclusion of additional damaging polymorphisms in the star allele. These findings are critical for clinical implementation of metabolizer phenotype prediction because a fraction of the population may be incorrectly considered normal metabolizers but actually may be poor or intermediate metabolizers.Peer reviewe
Clinical course and therapeutic approach to varicella zoster virus infection in children with rheumatic autoimmune diseases under immunosuppression.
To analyze the clinical presentation and complications of varicella zoster virus (VZV) infection in children with rheumatic diseases treated with immunosuppressive medication such as biological disease-modifying antirheumatic drugs (bDMARDs) and/or conventional disease-modifying antirheumatic drugs (cDMARDs), and to analyze the therapeutic approach to VZV infections with respect to the concomitant immunosuppressive treatment.
Retrospective multicenter study using the Swiss Pediatric Rheumatology registry. Children with rheumatic diseases followed in a Swiss center for pediatric rheumatology and treated with cDMARD and/or bDMARD with a clinical diagnosis of varicella or herpes zoster between January 2004 and December 2013 were included.
Twenty-two patients were identified, of whom 20 were treated for juvenile idiopathic arthritis, 1 for a polyglandular autoimmune syndrome type III, and 1 for uveitis. Of these 22 patients, 16 had varicella and 6 had herpes zoster. Median age at VZV disease was 7.6 years (range 2 to 17 years), with 6.3 years (range 2 to 17 years) for those with varicella and 11.6 years (range 5 to 16 years) for those with herpes zoster. The median interval between start of immunosuppression and VZV disease was 14.1 months (range 1 to 63 months). Two patients had received varicella vaccine (1 dose each) prior to start of immunosuppression. Concomitant immunosuppressive therapy was methotrexate (MTX) monotherapy (n = 9) or bDMARD monotherapy (n = 2), or a combination of bDMARD with prednisone, MTX or Leflunomide (n = 11). Four patients experienced VZV related complications: cellulitis in 1 patient treated with MTX, and cellulitis, sepsis and cerebellitis in 3 patients treated with biological agents and MTX combination therapy. Six children were admitted to hospital (range of duration: 4 to 9 days) and 12 were treated with valaciclovir or aciclovir.
The clinical course of varicella and herpes zoster in children under immunosuppression is variable, with 4 (18 %) of 22 children showing a complicated course. Thorough assessment of VZV disease and vaccination history and correct VZV vaccination according to national guidelines at diagnosis of a rheumatic autoimmune disease is essential to minimize VZV complications during a later immunosuppressive treatment
UWB through-the-Wall Propagation
The propagation of ultrawideband (UWB) signals in indoor environments is an important issue with significant impacts on the future direction and scope of UWB technology. The propagation of UWB signals is governed, among other things, by the properties of materials in the propagation medium. The information on electromagnetic properties of construction materials in the UWB frequency range would provide valuable insights into the appreciation of the capabilities and limitations of UWB technology. Although electromagnetic properties of certain construction materials over relatively narrow bandwidths in GHz frequency ranges are available, ultrawideband characterisation of most typical construction materials for UWB communication purposes has not been reported. In narrowband wireless communications, only the magnitude of insertion loss has been the quantity of interest. But for UWB signals, in addition to the magnitude, the phase information is an equally important factor that needs to be accounted for. In fact, UWB signals not only suffer attenuation when propagating through walls, but also suffer distortion due to the dispersive properties of the walls. This research examines propagation through typical construction materials and their ultrawideband characterisation. Ten commonly used construction materials are chosen for this investigation. Results for the dielectric constant and loss tangent of the materials over the UWB frequency range are presented. Accuracy of the measured results is discussed and distortions of UWB signals due to the dispersive properties of wall materials are addressed
Аналіз деформування матеріалу з множинними тріщинами термомеханічної втоми як розломно-блокового середовища
Recent advances in cancer biology have emerged important roles for microRNAs (miRNAs) in regulating tumor responses. However, their function in mediating intercellular communication within the tumor microenvironment is thus far poorly explored. Here, we found miR-206 to be abrogated in human pancreatic ductal adenocarcinoma (PDAC) specimens and cell lines. We show that miR-206 directly targets the oncogenes KRAS and annexin a2 (ANXA2), thereby acting as tumor suppressor in PDAC cells by blocking cell cycle progression, cell proliferation, migration and invasion. Importantly, we identified miR-206 as a negative regulator of oncogenic KRAS-induced nuclear factor-kappa B transcriptional activity, resulting in a concomitant reduction of the expression and secretion of pro-angiogenic and pro-inflammatory factors including the cytokine interleukin-8, the chemokines (C-X-C motif) ligand 1 and (C-C motif) ligand 2, and the granulocyte macrophage colony-stimulating factor. We further show that miR-206 abrogates the expression and secretion of the potent pro-lymphangiogenic factor vascular endothelial growth factor C in pancreatic cancer cells through an NF-kappa B-independent mechanism. By using in vitro and in vivo approaches, we reveal that re-expression of miR-206 in PDAC cells is sufficient to inhibit tumor blood and lymphatic vessel formation, thus leading to a significant delay of tumor growth and progression. Taken together, our study sheds light onto the role of miR-206 as a pleiotropic modulator of different hallmarks of cancer, and as such raising the intriguing possibility that miR-206 may be an attractive candidate for miRNA-based anticancer therapies.Funding Agencies|German Federal Ministry of Education and Research (NGFN grant) [01GS0816]; Deutsche Forschungsgemeinschaft (DIP project) [WI3499/1-1]</p
Path-loss and time dispersion parameters for indoor UWB propagation
The propagation of ultra wideband (UWB) signals in indoor environments is an important issue with significant impacts on the future direction and scope of the UWB technology and its applications. The objective of this work is to obtain a better assessment of the potentials of UWB indoor communications by characterizing the UWB indoor communication channels. Channel characterization refers to extracting the channel parameters from measured data. An indoor UWB measurement campaign is undertaken. Time-domain indoor propagation measurements using pulses with less than 100 ps width are carried out. Typical indoor scenarios, including line-of-sight (LOS), non-line-of-sight (NLOS), room-to-room, within-the-room, and hallways, are considered. Results for indoor propagation measurements are presented for local power delay profiles (local PDP) and small-scale averaged power delay profiles (SSA-PDP). Site-specific trends and general observations are discussed. The results for path-loss exponent and time dispersion parameters are presented
Amyloid-like aggregates sequester numerous metastable proteins with essential cellular functions
Protein aggregation is linked with neurodegeneration and numerous other diseases by mechanisms that are not well understood. Here, we have analyzed the gain-of-function toxicity of artificial β sheet proteins that were designed to form amyloid-like fibrils. Using quantitative proteomics, we found that the toxicity of these proteins in human cells correlates with the capacity of their aggregates to promote aberrant protein interactions and to deregulate the cytosolic stress response. The endogenous proteins that are sequestered by the aggregates share distinct physicochemical properties: They are relatively large in size and significantly enriched in predicted unstructured regions, features that are strongly linked with multifunctionality. Many of the interacting proteins occupy essential hub positions in cellular protein networks, with key roles in chromatin organization, transcription, translation, maintenance of cell architecture and protein quality control. We suggest that amyloidogenic aggregation targets a metastable subproteome, thereby causing multifactorial toxicity and, eventually, the collapse of essential cellular functions. PaperFlick: © 2011 Elsevier Inc
- …