520 research outputs found

    Diurnal and seasonal changes in stem radius increment and sap flow density indicate different responses of two co-existing oak species to environmental stress

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    Using continuous monitoring of stem radius combined with sap flow measurements we assessed the effects of environmental conditions on tree radial growth and water status of two co- existing oak species ( Quercus petraea and Quercus cerris ) at high resolution time in growing seasons of 2008 and 2009. The forest (95–100 yr) is situated in a xeric site in the transition zone between forested and forest-steppe regions in north -eastern Hungary, BĂŒkk mountains (47 o 90’N, 20 o 46’E, elevation 320–340 m a.s.l.). Weather conditio ns in the growing season of 2008 (total rainfall 354 mm, mean daily temperature 17.0 o C) was less extreme than in 2009 (total rainfall 299 mm, temperature 17.9 o C). Rainfall strongly determined the course of radi al growth increment in trees. Radial growth of trees was limited in 200 9 due to the drought in spring. The maximum radial increment of both species was achieved three weeks earlier (4 th week of June) than in 2008 (4 th week of July). We used dendrometer monitoring data for estimation of stem (tree) water deficit ( ∆ W) by measuring water-related changes in stem radiu s (Zweifel et al. 2005). The magnitude of tree water deficit variation ( ∆ W) was always smaller in Q. cerris than in Q. petraea. In contrast, Quercus cerris always exhibited larger daytime averages and maxima of sap flow density. In August of 2009 when drought became seve re there were larger increases in tree water deficit ( ∆ W) (50–55 %) in both species compared to July as it could be expected from the extent of decreases in sap flow density (24–28%). Our data suggested that due to the low SWC the transpiration was supported mainly from the inner w ater storage of trees during prolonged drought which resulted in high stem water deficit ( ∆ W)

    Radiation Tolerance Qualification Tests of the Final Source Interface Unit for the ALICE Experiment

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    The ALICE Detector Data Link (DDL) is a high-speed optical link designed to interface the readout electronics of ALICE sub-detectors to the DAQ computers. The Source Interface Unit (SIU) of the DDL will operate in radiation environment. Previous tests showed that a configuration loss of SRAM-based FPGA devices may happen and the frequency of undetected data errors in the FPGA user memory area is also not acceptable. Therefore, we redesigned the SIU card using another FPGA based on flash technology. In order to detect bit errors in the user memory we added parity check logic to the design. The new SIU has been extensively tested using neutron and proton irradiation to verify its radiation tolerance. In this paper we summarize the design changes, introduce the final design, and the results of the radiation tolerance measurements on the final card

    Endothelial cell activation is attenuated by everolimus via transcriptional and post-transcriptional regulatory mechanisms after drug-eluting coronary stenting.

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    We previously found higher level of endothelial cell (EC) activation in patients who suffered from in-stent restenosis after bare-metal stenting compared to subjects who underwent drug-eluting stenting (DES) showing no complications. Here we investigated the potential transcriptional and post-transcriptional regulatory mechanisms by which everolimus attenuated EC activation after DES. We studied the effect of everolimus on E-selectin (SELE) and VCAM1 mRNA levels when human coronary artery (HCAECs) and human umbilical vein ECs were challenged with recombinant TNF-alpha (100 ng/mL) for 1-24 hours in the presence or absence of everolimus using 0.5 muM concentration locally maintained by DES. EC activation was evaluated via the levels of IL-1beta and IL-6 mRNAs with miR-155 expression by RT-qPCR as well as the nuclear translocation of nuclear factor kappa beta (NF-kappaB) detected by fluorescence microscopy. To investigate the transcriptional regulation of E-selectin and VCAM-1, TNF-alpha-induced enhancer RNA (eRNA) expression at p65-bound enhancers in the neighboring genomic regions of SELE and VCAM1 genes, including SELE_-11Kb and VCAM1_-10Kb, were measured in HCAECs. Mature and precursor levels of E-selectin and VCAM-1 repressor miR-181b were quantified to analyze the post-transcriptional regulation of these genes in HCAECs. Circulating miR-181b was analyzed in plasma samples of stented subjects by stem-loop RT-qPCR. TNF-alpha highly elevated E-selectin and VCAM-1 expression at transcriptional level in ECs. Levels of mature, pre- and pri-miR-181b were repressed in ECs by TNF-alpha, while everolimus acted as a negative regulator of EC activation via inhibited translocation of NF-kappaB p65 subunit into cell nuclei, lowered eRNA expression at SELE and VCAM1 genes-associated enhancers and modulated expression of their post-transcriptional repressor miR-181b. Significant negative correlation was observed between plasma miR-181b and soluble E-selectin and VCAM-1 in patients. In conclusion, everolimus attenuates EC activation via reduced NF-kappaB p65 translocation causing decreased E-selectin and VCAM-1 expression at transcriptional and post-transcriptional level after DES

    Development and performance of Triple-GEM detectors for the upgrade of the muon system of the CMS experiment

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    The CMS Collaboration is evaluating GEM detectors for the upgrade of the muon system. This contribution will focus on the R&D performed on chambers design features and will discuss the performance of the upgraded detector

    Overview of large area triple-GEM detectors for the CMS forward muon upgrade

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    In order to cope with the harsh environment expected from the high luminosity LHC, the CMS forward muon system requires an upgrade. The two main challenges expected in this environment are an increase in the trigger rate and increased background radiation leading to a potential degradation of the particle ID performance. Additionally, upgrades to other subdetectors of CMS allow for extended coverage for particle tracking, and adding muon system coverage to this region will further enhance the performance of CMS

    A novel application of Fiber Bragg Grating (FBG) sensors in MPGD

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    We present a novel application of Fiber Bragg Grating (FBG) sensors in the construction and characterisation of Micro Pattern Gaseous Detector (MPGD), with particular attention to the realisation of the largest triple (Gas electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 m2 active area each, employing three GEM foils per chamber, to be installed in the forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM foils that are mechanically stretched in order to secure their flatness and the consequent uniform performance of the GE1/1 chamber across its whole active surface. So far FBGs have been used in high energy physics mainly as high precision positioning and re-positioning sensors and as low cost, easy to mount, low space consuming temperature sensors. FBGs are also commonly used for very precise strain measurements in material studies. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used to determine the optimal mechanical tension applied and to characterise the mechanical tension that should be applied to the foils. We discuss the results of the test done on a full-sized GE1/1 final prototype, the studies done to fully characterise the GEM material, how this information was used to define a standard assembly procedure and possible future developments.Comment: 4 pages, 4 figures, presented by Luigi Benussi at MPGD 2015 (Trieste, Italy). arXiv admin note: text overlap with arXiv:1512.0848
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