1,294 research outputs found

    Application of Raman diagnostics to combustion

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    The use of laser Raman diagnostic techniques to measure the specie concentrations and their temperatures in combustion flow fields is discussed. The system designed to measure the specie concentrations, which included a ruby laser and a photodiode to trip the laser at the maximum light and heat output of the combustion process, is described and problems encountered in developing the system are reported. Photographs of the combustion process are presented and analyzed detailing the evolution of the combustion in terms of the photodiode and the lack of a noticeable Raman-Stokes signal. The absence of the Raman-Stokes signal is discussed

    The Heavy Photon Search test detector

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    The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment\u27s technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e(+)e(-) invariant mass spectrum above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW0(4) crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top bottom. This arrangement provides sensitivity to low mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e(+)e(-) pairs requires the first layer of silicon sensors be placed only 10 cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. Accordingly, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab. (C) 2014 The Authors. Published by Elsevier B.V

    Use of immediate-early gene expression to map relationships between limbic structures supporting memory

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    This thesis explores the influence of brain regions within the "extended hippocampal memory system" on the activity of the retrosplenial cortex in the rat. One of the first goals was to use lesion studies to improve the understanding of the vulnerability of the retrosplenial cortex, especially in the context of diencephalic and temporal lobe amnesia. The second was to assess what are the brain areas within the temporal lobe involved in object recognition and how they interact. These two objectives were made possible by visualising immediate-early gene expression. By combining this technique with lesions, distal effects of different lesions (hippocampus, mammillothalamic tract and fornix) on the activity of the retrosplenial cortex were measured. For object recognition, the immediate-early gene imaging enabled the assessment of normal brain activity in rats associated with behavioural discrimination of novelty. The lesion studies provide information about the specific and common vulnerability of the retrosplenial cortex, as all three distal lesions resulted in a decrease of immediate-early gene activity in the retrosplenial cortex. In addition, these findings unify diencephalic amnesia with temporal amnesia, and emphasize the need to study networks or systems instead of individual structure. The immediate-early gene/object recognition experiment implicated the caudal part of the perirhinal cortex (and Te2) and of the hippocampus in object recognition, and highlighted the importance of mapping brain region relationships within a connected system. Taken together, these experiments provide clear support for the concept of an extended hippocampal memory system, but also show how this system may interact with other structures involved in different forms of memory. The findings underlie the potential afforded by use of immediate-early gene expression techniques in animal studies.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    [Ag(PcL)]-Catalysed Domino Approach to 6-Substituted Benzoxazino Isoquinolines

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    In this paper, we describe a new silver catalysed domino approach to 6-substituted benzoxazino isoquinolines starting from 2-alkynylbenzaldehydes and 1-substituted-(2-aminophenyl)methanols. The strategy is characterized by good reaction yields, and can be performed at room temperature as well as under heating (conventional or dielectric) in different reaction times. Best results have been obtained by using silver complexes of macrocyclic pyridine-containing ligands (PcL) as catalysts. The stereoselectivity of the transformation has been investigated by using chiral reaction partners and chiral catalyst, but unfortunately, modest stereoselectivities has been achieved. On the other hand, this approach represents an alternative synthetic strategy for the preparation of 6-substituted benzoxazino isoquinolines, which are the key scaffold of some compounds endowed of biological activity

    New label-free methods for protein relative quantification applied to the investigation of an animal model of Huntington Disease

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    Spectral Counts approaches (SpCs) are largely employed for the comparison of protein expression profiles in label-free (LF) differential proteomics applications. Similarly, to other comparative methods, also SpCs based approaches require a normalization procedure before Fold Changes (FC) calculation. Here, we propose new Complexity Based Normalization (CBN) methods that introduced a variable adjustment factor (f), related to the complexity of the sample, both in terms of total number of identified proteins (CBN(P)) and as total number of spectral counts (CBN(S)). Both these new methods were compared with the Normalized Spectral Abundance Factor (NSAF) and the Spectral Counts log Ratio (Rsc), by using standard protein mixtures. Finally, to test the robustness and the effectiveness of the CBNs methods, they were employed for the comparative analysis of cortical protein extract from zQ175 mouse brains, model of Huntington Disease (HD), and control animals (raw data available via ProteomeXchange with identifier PXD017471). LF data were also validated by western blot and MRM based experiments. On standard mixtures, both CBN methods showed an excellent behavior in terms of reproducibility and coefficients of variation (CVs) in comparison to the other SpCs approaches. Overall, the CBN(P) method was demonstrated to be the most reliable and sensitive in detecting small differences in protein amounts when applied to biological samples
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