Spectral caustics in laser assisted Breit-Wheeler process

Electron-positron pair production by the Breit-Wheeler process embedded in a strong laser pulse is analyzed. The transverse momentum spectrum displays prominent peaks which are interpreted as caustics, the positions of which are accessible by the stationary phases. Examples are given for the superposition of an XFEL beam with an optical high-intensity laser beam. Such a configuration is available, e.g., at LCLS at present and at European XFEL in near future. It requires a counter propagating probe photon beam with high energy which can be generated by synchronized inverse Compton backscattering

Pair production by Schwinger and Breit-Wheeler processes in bi-frequent fields

Counter-propagating and suitably polarized light (laser) beams can provide conditions for pair production. Here, we consider in more detail the following two situations: (i) In the homogeneity regions of anti-nodes of linearly polarized ultra-high intensity laser beams, the Schwinger process is dynamically assisted by a second high-frequency field, e.g. by a XFEL beam. (ii) A high-energy probe photon beam colliding with a superposition of co-propagating intense laser and XFEL beams gives rise to the laser assisted Breit-Wheeler process. Prospects of such bi-frequent field constellations with respect to the feasibility of conversion of light into matter are discussed

Widespread occurrence of 5-methylcytosine in human coding and non-coding RNA

The modified base 5-methylcytosine (m5C) is well studied in DNA, but investigations of its prevalence in cellular RNA have been largely confined to tRNA and rRNA. In animals, the two m5C methyltransferases NSUN2 and TRDMT1 are known to modify specific tRNAs and have roles in the control of cell growth and differentiation. To map modified cytosine sites across a human transcriptome, we coupled bisulfite conversion of cellular RNA with next-generation sequencing. We confirmed 21 of the 28 previously known m5C sites in human tRNAs and identified 234 novel tRNA candidate sites, mostly in anticipated structural positions. Surprisingly, we discovered 10 275 sites in mRNAs and other non-coding RNAs. We observed that distribution of modified cytosines between RNA types was not random; within mRNAs they were enriched in the untranslated regions and near Argonaute binding regions. We also identified five new sites modified by NSUN2, broadening its known substrate range to another tRNA, the RPPH1 subunit of RNase P and two mRNAs. Our data demonstrates the widespread presence of modified cytosines throughout coding and non-coding sequences in a transcriptome, suggesting a broader role of this modification in the post-transcriptional control of cellular RNA function

The estrogen and c-Myc target gene HSPC111 is over-expressed in breast cancer and associated with poor patient outcome

Introduction: Estrogens play a pivotal role in the initiation and progression of breast cancer. The genes that mediate these processes are not fully defined, but potentially include the known mammary oncogene MYC. Characterization of estrogen-target genes may help to elucidate further the mechanisms of estrogen-induced mitogenesis and endocrine resistance.Methods: We used a transcript profiling approach to identify targets of estrogen and c-Myc in breast cancer cells. One previously uncharacterized gene, namely HBV pre-S2 trans-regulated protein 3 (HSPC111), was acutely upregulated after estrogen treatment or inducible expression of c-Myc, and was selected for further functional analysis using over-expression and knock-down strategies. HSPC111 expression was also analyzed in relation to MYC expression and outcome in primary breast carcinomas and published gene expression datasets.Results: Pretreatment of cells with c-Myc small interfering RNA abrogated estrogen induction of HSPC111, identifying HSPC111 as a potential c-Myc target gene. This was confirmed by the demonstration of two functional E-box motifs upstream of the transcription start site. HSPC111 mRNA and protein were over-expressed in breast cancer cell lines and primary breast carcinomas, and this was positively correlated with MYC mRNA levels. HSPC111 is present in a large, RNA-dependent nucleolar complex, suggesting a possible role in ribosomal biosynthesis. Neither over-expression or small interfering RNA knock-down of HSPC111 affected cell proliferation rates or sensitivity to estrogen/antiestrogen treatment. However, high expression of HSPC111 mRNA was associated with adverse patient outcome in published gene expression datasets.Conclusion: These data identify HSPC111 as an estrogen and c-Myc target gene that is over-expressed in breast cancer and is associated with an adverse patient outcome

System concept and process layout for a micro-CHP unit based on low temperature SOFC

Anode Supported Cells (ASC) are considered as a promising SOFC technology for achieving higher power densities at significantly reduced operating temperatures. Thereby it is commonly expected to enhance both the profitability and durability of fuel cell systems in real world applications. In the collaborative project LOTUS a micro-CHP system prototype will be developed and tested based on a novel ASC technology with an operating temperature of 650°C. The consortium gathered to work in this project incorporates a number of leading European SOFC-developers, system integrators and research institutes, namely the companies of HyGear Fuel Cell Systems (NL), SOFCPower (IT) and Domel (SLO) as well as the Fraunhofer IKTS (D), the EC Joint Research Centre (NL) and the University of Perugia (IT). Th e project is funded under EU 7th Framework Programme by the Fuel Cell and Hydrogen Joint Undertaking (FCH-JU), grant agreement No. 256694. In the first project phase the principle system design was developed strictly following a topdown approach based on a system requirements definition, a model based evaluation of applicable system concepts and a final process definition based on layout calculations and parameter studies. The Fraunhofer IKTS was leader of the work package system design and modeling. In the second phase of the project all required components and submodules are developed with respect to the given process design parameters. The core SOFC stack module with an operating temperature of 650°C will be provided by SOFCPower incorporating enhanced ASCs that are newly developed with support of the University of Perugia. A compact fuel processing module will be developed by HyGear based on air enhanced steam reforming and also enabling for a controllable proportional stack-internal reforming. The advanced fuel processing concept leads to a higher electrical efficiency and a variable power to heat ratio of the system, which is adjustable independently from the electric power output level. A novel exhaust suction fan with a significantly reduced power demand during all operational stages will be provided by Domel for system integration. Finally, in the third phase of the project, the setup and commissioning of the system prototype will be carried out, supported by a model based control logic development and failure mode analysis. The testing procedures, data analysis an d performance evaluation will be monitored by the EC Joint Research Centre

Methods to analyze microRNA-mediated control of mRNA translation

MicroRNAs (miRs) are an important class of gene regulators that affect a wide range of biological processes. Despite the early recognition of miRs as translational regulators and intense interest in studying this phenomenon, it has so far not been possible to derive a consensus model for the underlying molecular mechanism(s). The potential of miRs to act in a combinatorial manner and to also promote mRNA decay creates conceptual and technical challenges in their study. Here, we discuss critical parameters in design and analysis of experiments used to study miR function including creation of synthetic miR and mRNA partners for assay of translational inhibition using luciferase reporters; measurement of mRNA stability after miR action; defining poly(A) tail length in miR target mRNA; determining the distribution of miRs and their target mRNAs in polysome profiles; and visualization of P-body components. We describe protocols for each of these procedures

The Marburg Collection: A Golden Gate DNA Assembly Framework for Synthetic Biology Applications in Vibrio natriegens

Vibrio natriegens is known as the world's fastest growing organism with a doubling time of less than 10 min. This incredible growth speed empowers V. natriegens as a chassis for synthetic and molecular biology, potentially replacing E. coli in many applications. While first genetic parts have been built and tested for V. natriegens, a comprehensive toolkit containing well-characterized and standardized parts did not exist. To close this gap, we created the Marburg Collection-a highly flexible Golden Gate cloning toolbox optimized for the emerging chassis organism V. natriegens, containing 191 genetic parts. The Marburg Collection overcomes the paradigm of plasmid construction-integrating inserts into a backbone-by enabling the de novo assembly of plasmids from basic genetic parts. This allows users to select the plasmid replication origin and resistance part independently, which is highly advantageous when limited knowledge about the behavior of those parts in the target organism is available. Additional design highlights of the Marburg Collection are novel connector parts, which facilitate modular circuit assembly and, optionally, the inversion of individual transcription units to reduce transcriptional crosstalk in multigene constructs. To quantitatively characterize the genetic parts contained in the Marburg Collection in V. natriegens, we developed a reliable microplate reader measurement workflow for reporter experiments and overcame organism-specific challenges. We think the Marburg Collection with its thoroughly characterized parts will provide a valuable resource for the growing V. natriegens community

Industrial concentration and a Keynesian theory of distribution

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