6,547 research outputs found
Prospects for GPDs extraction with Double DVCS
Double deeply virtual Compton scattering (DDVCS) is the process where an
electron scatters off a nucleon and produces a lepton pair. The main advantage
of this process in contrast with deeply virtual and timelike Compton
scatterings (DVCS and TCS) is the possibility of directly measuring GPDs for
at leading order in (LO). We present a new calculation
of the DDVCS amplitude based on the methods developed by R. Kleiss and W. J.
Stirling in the 1980s. These techniques produce expressions for amplitudes that
are perfectly suited for implementation in numerical simulations. Via the
PARTONS software, the correctness of this new formulation has been tested by
comparing the DVCS and TCS limits of DDVCS with independent calculations of
DVCS and TCS.Comment: 5 pages, 4 figures, proceedings for the XXIX Cracow Epiphany
Conferenc
Phenomenology of double deeply virtual Compton scattering in the era of new experiments
We revisit the phenomenology of the deep exclusive electroproduction of a
lepton pair, i.e. double deeply virtual Compton scattering (DDVCS), in view of
new experiments planned in the near future. The importance of DDVCS in the
reconstruction of generalized parton distributions (GPDs) in their full
kinematic domain is emphasized. Using Kleiss-Stirling spinor techniques, we
provide the leading order complex amplitudes for both DDVCS and Bethe-Heithler
sub-processes. Such a formulation turns out to be convenient for practical
implementation in the PARTONS framework and EpIC Monte Carlo generator that we
use in simulation studies.Comment: 21 pages, 13 figure
Northern blotting analysis of microRNAs, their precursors and RNA interference triggers
<p>Abstract</p> <p>Background</p> <p>Numerous microRNAs (miRNAs) have heterogeneous ends resulting from imprecise cleavages by processing nucleases and from various non-templated nucleotide additions. The scale of miRNA end-heterogeneity is best shown by deep sequencing data revealing not only the major miRNA variants but also those that occur in only minute amounts and are unlikely to be of functional importance. All RNA interference (RNAi) technology reagents that are expressed and processed in cells are also exposed to the same machinery generating end-heterogeneity of the released short interfering RNAs (siRNAs) or miRNA mimetics.</p> <p>Results</p> <p>In this study we have analyzed endogenous and exogenous RNAs in the range of 20-70 nt by high-resolution northern blotting. We have validated the results obtained with northern blotting by comparing them with data derived from miRNA deep sequencing; therefore we have demonstrated the usefulness of the northern blotting technique in the investigation of miRNA biogenesis, as well as in the characterization of RNAi technology reagents.</p> <p>Conclusions</p> <p>The conventional northern blotting enhanced to high resolution may be a useful adjunct to other miRNA discovery, detection and characterization methods. It provides quantitative data on distribution of major length variants of abundant endogenous miRNAs, as well as on length heterogeneity of RNAi technology reagents expressed in cells.</p
Genetic basis for variation in wheat grain yield in response to varying nitrogen application
Nitrogen (N) is a major nutrient needed to attain optimal grain yield (GY) in all environments. Nitrogen fertilisers represent a significant production cost, in both monetary and environmental terms. Developing genotypes capable of taking up N early during development while limiting biomass production after establishment and showing high N-use efficiency (NUE) would be economically beneficial. Genetic variation in NUE has been shown previously. Here we describe the genetic characterisation of NUE and identify genetic loci underlying N response under different N fertiliser regimes in a bread wheat population of doubled-haploid lines derived from a cross between two Australian genotypes (RAC875 × Kukri) bred for a similar production environment. NUE field trials were carried out at four sites in South Australia and two in Western Australia across three seasons. There was genotype-by-environment- by-treatment interaction across the sites and also good transgressive segregation for yield under different N supply in the population. We detected some significant Quantitative Trait Loci (QTL) associated with NUE and N response at different rates of N application across the sites and years. It was also possible to identify lines showing positive N response based on the rankings of their Best Linear Unbiased Predictions (BLUPs) within a trial. Dissecting the complexity of the N effect on yield through QTL analysis is a key step towards elucidating the molecular and physiological basis of NUE in wheat.Saba Mahjourimajd, Julian Taylor, Beata Sznajder, Andy Timmins, Fahimeh Shahinnia, Zed Rengel, Hossein Khabaz-Saberi, Haydn Kuchel, Mamoru Okamoto, Peter Langridg
Between Apprehension and Support: Social Dialogue, Democracy, and Industrial Restructuring in Central and Eastern Europe
This article explores the attitudes of trade union organizations to restructuring and privatization of their enterprises to strategic foreign investors in Central and Eastern Europe\u27s biggest steel producers: Poland, Czech Republic, Romania, and Slovakia. Contrary to advocates of insulating technocratic decision-makers from social partners, this article argues that higher quality of democracy and concomitant social dialogue carried out at the level of the sector with union organizations that are autonomous of the government in power (as was the case in the Czech Republic and Poland), are associated with greater restructuring and with support for privatization to strategic foreign investors. In these circumstances, the unions actually pressure reluctant governments to accelerate the privatization process. By contrast, politically motivated capture of individual enterprise-level unions and splitting them from sectoral-level organizations, as occurred in countries with lower quality of democracy (Romania and Slovakia), weakens the autonomous sectoral-level organizations, which are generally supportive of restructuring. Conversely, captured unions remain far more resistant to reform than their counterparts belonging to autonomous sectoral organizations. Thus, higher quality of democracy and concomitant vibrant social dialogue safeguard industrial restructuring
Wp-2 basic investigation of transition effect
An important goal of the TFAST project was to study the effect of the location of transition in relation to the shock wave on the separation size, shock structure and unsteadiness of the interaction area. Boundary layer tripping (by wire or roughness) and flow control devices (Vortex Generators and cold plasma) were used for boundary layer transition induction. As flow control devices were used here in the laminar boundary layer for the first time, their effectiveness in transition induction was an important outcome. It was intended to determine in what way the application of these techniques induces transition. These methods should have a significantly different effect on boundary layer receptivity, i.e. the transition location. Apart from an improved understanding of operation control methods, the main objective was to localize the transition as far downstream as possible while ensuring a turbulent character of interaction. The final objective, involving all the partners, was to build a physical model of transition control devices. Establishing of such model would simplify the numerical approach to flow cases using such devices. This undertaking has strong support from the industry, which wants to include these control devices in the design process. Unfortunately only one method of streamwise vortices was developed and investigated in the presented study
Measurement of the Boson Mass
A measurement of the mass of the boson is presented based on a sample of
5982 decays observed in collisions at
= 1.8~TeV with the D\O\ detector during the 1992--1993 run. From a
fit to the transverse mass spectrum, combined with measurements of the
boson mass, the boson mass is measured to be .Comment: 12 pages, LaTex, style Revtex, including 3 postscript figures
(submitted to PRL
Search for Top Squark Pair Production in the Dielectron Channel
This report describes the first search for top squark pair production in the
channel stop_1 stopbar_1 -> b bbar chargino_1 chargino_1 -> ee+jets+MEt using
74.9 +- 8.9 pb^-1 of data collected using the D0 detector. A 95% confidence
level upper limit on sigma*B is presented. The limit is above the theoretical
expectation for sigma*B for this process, but does show the sensitivity of the
current D0 data set to a particular topology for new physics.Comment: Five pages, including three figures, submitted to PRD Brief Report
Search for Production via Trilepton Final States in collisions at TeV
We have searched for associated production of the lightest chargino,
, and next-to-lightest neutralino, , of the
Minimal Supersymmetric Standard Model in collisions at
\mbox{ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron
collider. Data corresponding to an integrated luminosity of 12.5 \ipb
were examined for events containing three isolated leptons. No evidence for
pair production was found. Limits on
BrBr are
presented.Comment: 17 pages (13 + 1 page table + 3 pages figures). 3 PostScript figures
will follow in a UUEncoded, gzip'd, tar file. Text in LaTex format. Submitted
to Physical Review Letters. Replace comments - Had to resumbmit version with
EPSF directive
Search for a Fourth Generation Charge -1/3 Quark via Flavor Changing Neutral Current Decay
We report on a search for pair production of a fourth generation charge -1/3
quark (b') in pbar p collisions at sqrt(s) = 1.8 TeV at the Fermilab Tevatron
using an integrated luminosity of 93 pb^-1. Both quarks are assumed to decay
via flavor changing neutral currents (FCNC). The search uses the signatures
gamma + 3 jets + mu-tag and 2 gamma + 2 jets. We see no significant excess of
events over the expected background. We place an upper limit on the production
cross section times branching fraction that is well below theoretical
expectations for a b' quark decaying exclusively via FCNC for b' quark masses
up to m(Z) + m(b).Comment: Eleven pages, two postscript figures, submitted to Physical Review
Letter
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