645 research outputs found
Exploratory QTL analyses of some pepper physiological traits in two environments
behind phenotypic differences and led to selection of genotypes having favourable traits. Continuous monitoring of environmental conditions has also become an accessible option. Rather than single trait evaluation, we would prefer smarter approaches capable of evaluating multiple, often correlated and time dependent traits simultaneously as a function of genes (QTLs) and environmental inputs, where we would The use of molecular breeding techniques has increased insight into the genetics like to include intermediate genomic information as well. In this paper, an exploratory QTL analysis over two environments was undertaken using available genetic and phenotypic data from segregating recombinant inbred lines (RIL) of pepper (Capsicum annuum). We focused on vegetative traits, e.g. stem length, speed of stem development, number of internodes etc. We seek to improve the estimation of allelic values of these traits under the two environments and determine possible QTL x E interaction. Almost identical QTLs are detected for each trait under the two environments but with varying LOD scores. No clear evidence was found for presence of QTL by environment interactions, despite differences in phenotypes and in magnitude of QTLs expression. Within the EU project SPICY (Voorrips et al., 2010 this issue), a larger number of environments will be studied and more advanced statistical analysis tools will be considered. The correlation between the traits will also be modelled. The identification of markers for the important QTL (Nicolaï et al., 2010 this issue) will improve the speed and accuracy of genomic prediction of these complex phenotype
Probing pre-formed alpha particles in the ground state of nuclei
In this Letter, we report on alpha particle emission through the nuclear
break-up in the reaction 40Ca on a 40Ca target at 50A MeV. It is observed that,
similarly to nucleons, alpha particles can be emitted to the continuum with
very specific angular distribution during the reaction. The alpha particle
properties can be understood as resulting from an alpha cluster in the daughter
nucleus that is perturbed by the short range nuclear attraction of the
collision partner and emitted. A time-dependent theory that describe the alpha
particle wave-function evolution is able to reproduce qualitatively the
observed angular distribution. This mechanism offers new possibilities to study
alpha particle properties in the nuclear medium.Comment: 4 pages, 3 figure
Comparison of two strategies for the start-up of a biological reactor for the treatment of hypersaline effluents from a table olive packaging industry
Biological treatment of hypersaline effluents with high organic matter concentrations is difficult to carry out and it can require a long start-up phase. This is the case of the treatment of fermentation brines from the table olive packaging (FTOP) industries. These effluents are characterized by conductivity values around 90 mS/cm, COD around 15,000 mg/L and total phenols concentration around 1000 mg/L. In this work, FTOP has been treated in two sequencing batch reactors (SBRs) operated in parallel. In each SBR a different start-up strategy has been carried out. In the SBR-2, biomass was previously acclimated to high salinity using simulated wastewater without phenolic compounds, meanwhile in the SBR-1, FTOP was added from the beginning of the start-up. Results indicated more operational problems in the SBR-2 consisting in a higher deflocculation that drove to high turbidity values in the effluent. Besides, at the end of the start-up, the SBR-1 reached higher COD removal efficiencies than SBR-2 (88% and 73%, respectively). In both reactors, an increase in gamma-Proteobacteria in the microbial population was observed for increasing conductivities. In addition, phenols were completely removed in both reactors at the end of the start-up, what implied very low toxicity values in the effluent.The authors of this work thank the financial support of CDTI (Centre for Industrial Technological Development) depending on the Spanish Ministry of Science and Innovation.Ferrer-Polonio, E.; Mendoza Roca, JA.; Iborra Clar, A.; Alonso Molina, JL.; Pastor Alcañiz, L. (2015). Comparison of two strategies for the start-up of a biological reactor for the treatment of hypersaline effluents from a table olive packaging industry. Chemical Engineering Journal. 273:595-602. doi:10.1016/j.cej.2015.03.062S59560227
The Magnus expansion and some of its applications
Approximate resolution of linear systems of differential equations with
varying coefficients is a recurrent problem shared by a number of scientific
and engineering areas, ranging from Quantum Mechanics to Control Theory. When
formulated in operator or matrix form, the Magnus expansion furnishes an
elegant setting to built up approximate exponential representations of the
solution of the system. It provides a power series expansion for the
corresponding exponent and is sometimes referred to as Time-Dependent
Exponential Perturbation Theory. Every Magnus approximant corresponds in
Perturbation Theory to a partial re-summation of infinite terms with the
important additional property of preserving at any order certain symmetries of
the exact solution. The goal of this review is threefold. First, to collect a
number of developments scattered through half a century of scientific
literature on Magnus expansion. They concern the methods for the generation of
terms in the expansion, estimates of the radius of convergence of the series,
generalizations and related non-perturbative expansions. Second, to provide a
bridge with its implementation as generator of especial purpose numerical
integration methods, a field of intense activity during the last decade. Third,
to illustrate with examples the kind of results one can expect from Magnus
expansion in comparison with those from both perturbative schemes and standard
numerical integrators. We buttress this issue with a revision of the wide range
of physical applications found by Magnus expansion in the literature.Comment: Report on the Magnus expansion for differential equations and its
applications to several physical problem
The Dependence of the Superconducting Transition Temperature of Organic Molecular Crystals on Intrinsically Non-Magnetic Disorder: a Signature of either Unconventional Superconductivity or Novel Local Magnetic Moment Formation
We give a theoretical analysis of published experimental studies of the
effects of impurities and disorder on the superconducting transition
temperature, T_c, of the organic molecular crystals kappa-ET_2X and beta-ET_2X
(where ET is bis(ethylenedithio)tetrathiafulvalene and X is an anion eg I_3).
The Abrikosov-Gorkov (AG) formula describes the suppression of T_c both by
magnetic impurities in singlet superconductors, including s-wave
superconductors and by non-magnetic impurities in a non-s-wave superconductor.
We show that various sources of disorder lead to the suppression of T_c as
described by the AG formula. This is confirmed by the excellent fit to the
data, the fact that these materials are in the clean limit and the excellent
agreement between the value of the interlayer hopping integral, t_perp,
calculated from this fit and the value of t_perp found from angular-dependant
magnetoresistance and quantum oscillation experiments. If the disorder is, as
seems most likely, non-magnetic then the pairing state cannot be s-wave. We
show that the cooling rate dependence of the magnetisation is inconsistent with
paramagnetic impurities. Triplet pairing is ruled out by several experiments.
If the disorder is non-magnetic then this implies that l>=2, in which case
Occam's razor suggests that d-wave pairing is realised. Given the proximity of
these materials to an antiferromagnetic Mott transition, it is possible that
the disorder leads to the formation of local magnetic moments via some novel
mechanism. Thus we conclude that either kappa-ET_2X and beta-ET_2X are d-wave
superconductors or else they display a novel mechanism for the formation of
localised moments. We suggest systematic experiments to differentiate between
these scenarios.Comment: 18 pages, 5 figure
Spectroscopy of the unbound nucleus 18Na
Expérience GANIL, SPIRALInternational audienceThe unbound nucleus 18Na, the intermediate nucleus in the two-proton radioactivity of 19Mg, is studied through the resonant elastic scattering 17Ne(p,17Ne)p. The spectroscopic information obtained in this experiment is discussed and put in perspective with previous measurements and the structure of the mirror nucleus 18N
A Pearson-Dirichlet random walk
A constrained diffusive random walk of n steps and a random flight in Rd,
which can be expressed in the same terms, were investigated independently in
recent papers. The n steps of the walk are identically and independently
distributed random vectors of exponential length and uniform orientation.
Conditioned on the sum of their lengths being equal to a given value l,
closed-form expressions for the distribution of the endpoint of the walk were
obtained altogether for any n for d=1, 2, 4 . Uniform distributions of the
endpoint inside a ball of radius l were evidenced for a walk of three steps in
2D and of two steps in 4D. The previous walk is generalized by considering step
lengths which are distributed over the unit (n-1) simplex according to a
Dirichlet distribution whose parameters are all equal to q, a given positive
value. The walk and the flight above correspond to q=1. For any d >= 3, there
exist, for integer and half-integer values of q, two families of
Pearson-Dirichlet walks which share a common property. For any n, the d
components of the endpoint are jointly distributed as are the d components of a
vector uniformly distributed over the surface of a hypersphere of radius l in a
space Rk whose dimension k is an affine function of n for a given d. Five
additional walks, with a uniform distribution of the endpoint in the inside of
a ball, are found from known finite integrals of products of powers and Bessel
functions of the first kind. They include four different walks in R3 and two
walks in R4. Pearson-Liouville random walks, obtained by distributing the total
lengths of the previous Pearson-Dirichlet walks, are finally discussed.Comment: 33 pages 1 figure, the paper includes the content of a recently
submitted work together with additional results and an extended section on
Pearson-Liouville random walk
Hadron Energy Reconstruction for the ATLAS Calorimetry in the Framework of the Non-parametrical Method
This paper discusses hadron energy reconstruction for the ATLAS barrel
prototype combined calorimeter (consisting of a lead-liquid argon
electromagnetic part and an iron-scintillator hadronic part) in the framework
of the non-parametrical method. The non-parametrical method utilizes only the
known ratios and the electron calibration constants and does not require
the determination of any parameters by a minimization technique. Thus, this
technique lends itself to an easy use in a first level trigger. The
reconstructed mean values of the hadron energies are within of the
true values and the fractional energy resolution is . The value of the ratio
obtained for the electromagnetic compartment of the combined calorimeter is
and agrees with the prediction that for this
electromagnetic calorimeter. Results of a study of the longitudinal hadronic
shower development are also presented. The data have been taken in the H8 beam
line of the CERN SPS using pions of energies from 10 to 300 GeV.Comment: 33 pages, 13 figures, Will be published in NIM
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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