2,724 research outputs found
Charm and beauty quark masses in the MMHT2014 global PDF analysis
We investigate the variation in the MMHT2014 PDFs when we allow the heavy-quark masses mcmc and mbmb to vary away from their default values. We make PDF sets available in steps of Δmc=0.05 GeVΔmc=0.05 GeV and Δmb=0.25 GeVΔmb=0.25 GeV , and present the variation in the PDFs and in the predictions. We examine the comparison to the HERA data on charm and beauty structure functions and note that in each case the heavy-quark data, and the inclusive data, have a slight preference for lower masses than our default values. We provide PDF sets with three and four active quark flavours, as well as the standard value of five flavours. We use the pole mass definition of the quark masses, as in the default MMHT2014 analysis, but briefly comment on the MS¯¯¯¯¯¯¯MS¯ definition
Ad Lucem: QED parton distribution functions in the MMHT framework
We present the MMHT2015qed PDF set, resulting from the inclusion of QED corrections to the existing set of MMHT Parton Distribution Functions (PDFs), and which contain the photon PDF of the proton. Adopting an input distribution from the LUXqed formulation, we discuss our methods of including QED effects for the full, coupled DGLAP evolution of all partons with QED at O(α) , O(ααS) , O(α2) . While we find consistency for the photon PDF of the proton with other recent sets, building on this we also present a set of QED corrected neutron PDFs and provide the photon PDF separated into its elastic and inelastic contributions. The effect of QED corrections on the other partons and the fit quality is investigated, and the sources of uncertainty for the photon are outlined. Finally we explore the phenomenological implications of this set, giving the partonic luminosities for both the elastic and inelastic contributions to the photon and the effect of our photon PDF on fits to high mass Drell–Yan production, including the photon-initiated channel
MMHT PDFs: Updates and Outlook
We present the latest results of studies within the MMHT PDF framework. We discuss the impact of the most recent ATLAS 7 TeV jet data, demonstrating that while a good fit can be achieved for individual jet rapidity bins, it is not possible to achieve a good description of the data when all bins are fitted. We examine the role that the experimental correlated systematic uncertainties play in this, and demonstrate that by simply decorrelating no more than two sources of error between rapidity bins, a remarkably improved description of the data can be achieved. We then study the impact of NNLO corrections, showing that a mild decrease in the fit quality is produced. We also present the results of including new LHC W, Z, W + c and tt¯ data on the MMHT14 PDF set, showing that a marked decrease in the s + ¯s uncertainty is in particular achieved. Finally, some discussion of the latest work towards the inclusion of the photon PDF within the MMHT framework is presented
Estimation of Buttiker-Landauer traversal time based on the visibility of transmission current
We present a proposal for the estimation of B\"uttiker-Landauer traversal
time based on the visibility of transmission current. We analyze the tunneling
phenomena with a time-dependent potential and obtain the time-dependent
transmission current. We found that the visibility is directly connected to the
traversal time. Furthermore, this result is valid not only for rectangular
potential barrier but also for general form of potential to which the WKB
approximation is applicable . We compared these results with the numerical
values obtained from the simulation of Nelson's quantum mechanics. Both of them
fit together and it shows our method is very effective to measure
experimentally the traversal time.Comment: 12 pages, REVTeX, including 7 eps figure
Preeclampsia is associated with compromized maternal synthesis of long chain polyunsaturated fatty acids leading to offspring deficiency
Obesity and excessive lipolysis are implicated in preeclampsia (PE). Intrauterine growth restriction is associated with low maternal body mass index and decreased lipolysis. Our aim was to assess how maternal and offspring fatty acid metabolism is altered in mothers in the third trimester of pregnancy with PE (n=62) or intrauterine growth restriction (n=23) compared with healthy pregnancies (n=164). Markers of lipid metabolism and erythrocyte fatty acid concentrations were measured. Maternal adipose tissue fatty acid composition and mRNA expression of adipose tissue fatty acid–metabolizing enzymes and placental fatty acid transporters were compared. Mothers with PE had higher plasma triglyceride (21%, P<0.001) and nonesterified fatty acid (50%, P<0.001) concentrations than controls. Concentrations of major n−6 and n−3 long-chain polyunsaturated fatty acids in erythrocytes were 23% to 60% lower (all P<0.005) in PE and intrauterine growth restriction mothers and offspring compared with controls. Subcutaneous adipose tissue Δ−5 and Δ−6 desaturase and very long-chain fatty acid elongase mRNA expression was lower in PE than controls (respectively, mean [SD] control 3.38 [2.96] versus PE 1.83 [1.91], P=0.030; 3.33 [2.25] versus 1.03 [0.96], P<0.001; 0.40 [0.81] versus 0.00 [0.00], P=0.038 expression relative to control gene [square root]). Low maternal and fetal long-chain polyunsaturated fatty acid concentrations in PE may be the result of decreased maternal synthesis
Spectroscopic Investigation of the Activation of a Chromium-Pyrrolyl Ethene Trimerization Catalyst
1-Hexene
is an important α-olefin for polyethylene production
and is produced from ethene. Recent developments in the α-olefin
industry have led to the successful commercialization of ethene trimerization
catalysts. An important industrially applied ethene trimerization
system uses a mixture of chromium 2-ethylhexanoate, AlEt3, AlEt2Cl, and 2,5-dimethylpyrrole (DMP). Here, we have
studied the activation of this system using catalytic and spectroscopic
experiments (XAS, EPR, and UV–vis) under conditions employed
in industry. First, chromium 2-ethylhexanoate was prepared and characterized
to be [Cr3OÂ(RCO2)6(H2O)3]ÂCl. Next, the activation of chromium 2-ethylhexanoate with
AlEt3, AlEt2Cl, and DMP was studied, showing
immediate reduction (<5 ms) of the trinuclear CrÂ(III) carboxylate
and formation of a neutral polynuclear CrÂ(II) carboxylate complex.
Over time, this CrÂ(II) carboxylate complex is partially converted
into a chloro-bridged dinuclear CrÂ(II) pyrrolyl complex. In cyclohexane,
small quantities of an unknown CrÂ(I) complex (∼1% after 1 h)
are observed, while in toluene, the quantity of CrÂ(I) is much higher
(∼23% after 1 h). This is due to the formation of cationic
bisÂ(tolyl)ÂCrÂ(I) complexes, which likely leads to the observed inferior
performance using toluene as the reaction solvent. Catalytic studies
allow us to exclude some of the observed CrÂ(I) and CrÂ(II) complexes
as the active species in this catalytic system. Using this combination
of techniques, we have been able to structurally characterize complexes
of this selective Cr-catalyzed trimerization system under conditions
which are employed in industry
Energy prices in Europe. Evidence of persistence across markets
This paper deals with the behavior of energy price changes and how their shocks exert an impact on suppliers and
consumers in different markets. For this purpose, a fractional integration model is used to evaluate the persistence and mean reversion in prices across the major European markets (Germany, France, Italy, UK, Spain). We
compare the results with other major players as the US and Japan, to understand, first, if the European behavior
is different, and second, if geopolitical shocks that are affecting this market are expected to be permanent.
Empirical results show evidence of mean reversion properties in European prices, though some minor differences
arise from market to market that apparently, are not associated with the energy generation strategies followed by
each country. Thus, it will likely be expected following the current energy shocks the series will recover due to
natural market forces, without the need for additional policies
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Status Review of Wildlife Mitigation at 14 of 27 Major Hydroelectric Projects in Idaho, 1983-1984 Final Report.
The Pacific Northwest Electric Power Planning and Conservation Act and wildlife and their habitats in the Columbia River Basin and to compliance with the Program, the wildlife mitigation status reports coordination with resource agencies and Indian Tribes. developed the Columbia River Basin Fish and Wildlife Program development, operation, and maintenance of hydroelectric projects on existing agreements; and past, current, and proposed wildlife factual review and documentation of existing information on wildlife meet the requirements of Measure 1004(b)(l) of the Program. The mitigation, enhancement, and protection activities were considered. In mitigate for the losses to those resources resulting from the purpose of these wildlife mitigation status reports is to provide a resources at some of the Columbia River Basin hydroelectric projects the river and its tributaries. To accomplish this goal, the Council were written with the cooperation of project operators, and in within Idaho
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