Classical and quantum radiation from a moving charge in an expanding universe

We investigate photon emission from a moving particle in an expanding universe. This process is analogous to the radiation from an accelerated charge in the classical electromagnetic theory. Using the framework of quantum field theory in curved spacetime, we demonstrate that the Wentzel-Kramers-Brillouin (WKB) approximation leads to the Larmor formula for the rate of the radiation energy from a moving charge in an expanding universe. Using exactly solvable models in a radiation-dominated universe and in a Milne universe, we examine the validity of the WKB formula. It is shown that the quantum effect suppresses the radiation energy in comparison with the WKB formula.Comment: 16 pages, JCAP in pres

MicroRNA-155 expression is independently predictive of outcome in chordoma.

BackgroundChordoma pathogenesis remains poorly understood. In this study, we aimed to evaluate the relationships between microRNA-155 (miR-155) expression and the clinicopathological features of chordoma patients, and to evaluate the functional role of miR-155 in chordoma.MethodsThe miRNA expression profiles were analyzed using miRNA microarray assays. Regulatory activity of miR-155 was assessed using bioinformatic tools. miR-155 expression levels were validated by reverse transcription-polymerase chain reaction. The relationships between miR-155 expression and the clinicopathological features of chordoma patients were analyzed. Proliferative, migratory and invasive activities were assessed by MTT, wound healing, and Matrigel invasion assays, respectively.ResultsThe miRNA microarray assay revealed miR-155 to be highly expressed and biologically active in chordoma. miR-155 expression in chordoma tissues was significantly elevated, and this expression correlated significantly with disease stage (p = 0.036) and the presence of metastasis (p = 0.035). miR-155 expression also correlated significantly with poor outcomes for chordoma patients (hazard ratio, 5.32; p = 0.045). Inhibition of miR-155 expression suppressed proliferation, and the migratory and invasive activities of chordoma cells.ConclusionsWe have shown miR-155 expression to independently affect prognosis in chordoma. These results collectively indicate that miR-155 expression may serve not only as a prognostic marker, but also as a potential therapeutic target in chordoma

Center of Excellence in Research Reporting in Neurosurgery - Diagnostic Ontology

Motivation: Evidence-based medicine (EBM), in the field of neurosurgery, relies on diagnostic studies since Randomized Controlled Trials (RCTs) are uncommon. However, diagnostic study reporting is less standardized which increases the difficulty in reliably aggregating results. Although there have been several initiatives to standardize reporting, they have shown to be sub-optimal. Additionally, there is no central repository for storing and retrieving related articles. Results: In our approach we formulate a computational diagnostic ontology containing 91 elements, including classes and sub-classes, which are required to conduct Systematic Reviews - Meta Analysis (SR-MA) for diagnostic studies, which will assist in standardized reporting of diagnostic articles. SR-MA are studies that aggregate several studies to come to one conclusion for a particular research question. We also report high percentage of agreement among five observers as a result of the interobserver agreement test that we conducted among them to annotate 13 articles using the diagnostic ontology. Moreover, we extend our existing repository CERR-N to include diagnostic studies. Availability: The ontology is available for download as an.owl file at: http://bioportal.bioontology.org/ontologies/3013

MicroRNA-155 expression is independently predictive of outcome in chordoma.

BackgroundChordoma pathogenesis remains poorly understood. In this study, we aimed to evaluate the relationships between microRNA-155 (miR-155) expression and the clinicopathological features of chordoma patients, and to evaluate the functional role of miR-155 in chordoma.MethodsThe miRNA expression profiles were analyzed using miRNA microarray assays. Regulatory activity of miR-155 was assessed using bioinformatic tools. miR-155 expression levels were validated by reverse transcription-polymerase chain reaction. The relationships between miR-155 expression and the clinicopathological features of chordoma patients were analyzed. Proliferative, migratory and invasive activities were assessed by MTT, wound healing, and Matrigel invasion assays, respectively.ResultsThe miRNA microarray assay revealed miR-155 to be highly expressed and biologically active in chordoma. miR-155 expression in chordoma tissues was significantly elevated, and this expression correlated significantly with disease stage (p = 0.036) and the presence of metastasis (p = 0.035). miR-155 expression also correlated significantly with poor outcomes for chordoma patients (hazard ratio, 5.32; p = 0.045). Inhibition of miR-155 expression suppressed proliferation, and the migratory and invasive activities of chordoma cells.ConclusionsWe have shown miR-155 expression to independently affect prognosis in chordoma. These results collectively indicate that miR-155 expression may serve not only as a prognostic marker, but also as a potential therapeutic target in chordoma

Aberrant DNA methylations in chondrosarcoma

Chondrosarcoma (CS) is the second most common primary malignant bone tumor. Unlike other bone tumors, CS is highly resistant to conventional chemotherapy and radiotherapy, thus resulting in poor patient outcomes. There is an urgent need to establish alternative therapies for CS. However, the etiology and pathogenesis of CS still remain elusive. Recently, DNA methylation-associated epigenetic changes have been found to play a pivotal role in the initiation and development of human cancers, including CS, by regulating target gene expression in different cellular pathways. Elucidating the mechanisms of DNA methylation alteration may provide biomarkers for diagnosis and prognosis, as well as novel treatment options for CS. We have conducted a critical review to summarize the evidence regarding aberrant DNA methylation patterns as diagnostic biomarkers, predictors of progression and potential treatment strategies in CS

Background impurities and a delta-doped QW. Part I: Center doping

The influence of shallow background donor impurities on the energy characteristics of the SiGe/Si/SiGe quantum well structure with centered delta-doping is studied numerically. The description of the self-consistent method includes the calculation of the donors impurity binding energy in the delta-layer. The delta-layer impurity binding energy as well as the energy differences between the first quantized electron subbands in the well demonstrate a significant dependence on the characteristics of the background doping. Therefore, the background doping cannot be neglected when studying phenomena like intersubband optical transitions. © 2019 IOP Publishing Ltd