911 research outputs found
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Investigating postharvest chilling injury in tomato (Solanum lycopersicum L.) fruit using magnetic resonance imaging and 5-azacytidine, a hypomethylation agent
Tomato, like most species from tropical and subtropical regions, exhibits postharvest chilling injury (PCI) when stored at low temperatures. Because of its economic importance and the functional genomics tools available, we used tomato to investigate aspects of fruit PCI development. We asked two questions: First, are there spatial-temporal differences in the development of PCI that can be detected by magnetic resonance imaging (MRI)? Here, the aim was to use a non-invasive method to study PCI progression in vivo. At mature green and breaker, the pericarp, locular tissue and columella produced distinct D-values while in contrast, there was no such differentiation in riper fruit. Although the pericarp is where most PCI symptoms are visible, this tissue showed less dynamism upon cold exposure, compared to the inner tissues as detected by MRI. This suggests the occurrence of distinct, independently modulated mechanisms contributing to the development of PCI-symptomatology. Collectively our data showed that the MRI could detect fruit ripening, its attenuation by cold, and fruit tissue-specific responses to chilling stress. The second question we asked was if epigenetic modification of the tomato genome or transcriptome influences PCI response. We examined PCI severity in fruit injected with a demethylating agent, 5- azacytidine (AZA). Two tomato genotypes exposed to varying severities of cold-stress were studied. Results suggested that AZA was able to moderate PCI in 'Micro-Tom' after 3 weeks at 2.5°C, while different patterns were observed in 'Sun Cherry' across various cold treatments. The effects of AZA on PCI were complex, multilayered and highly context-dependent
The golden hello and political transitions
© 2017. We analyze the influence of IMF and World Bank programs on political regime transitions. We develop an extended version of Acemoglu and Robinson's [American Economic Review 91, 2001] model of political transitions to show how the anticipation of new loans from international financial institutions can trigger political transitions which would not otherwise have taken place. We test this unexplored implication of the theory empirically. We find that the anticipation of receiving new loan programs immediately af ter a political regime transition increases the probability of a transition from autocracy to democracy and reduces the probability of democratic survival
Hierarchical Planning Methodology for a Supply Chain Management
Hierarchical production planning is a widely utilized methodology for real world capacitated production planning systems with the aim of establishing different decision–making levels of the planning issues on the time horizon considered. This paper presents a hierarchical approach proposed to a company that produces reusable shopping bags in Chile and Perú, to determine the optimal allocation of resources at the tactical level as well as over the most immediate planning horizon to meet customer demands for the next weeks. Starting from an aggregated production planning model, the aggregated decisions are disaggregated into refined decisions in two levels, using a couple of optimization models that impose appropriate constraints to keep coherence of the plan on the production system. The main features of the hierarchical solution approach are presented
Recommended from our members
The Golden Hello and Political Transitions
We analyze the influence of IMF and World Bank programs on political regime transitions. We develop an extended version of Acemoglu and Robinson's [American Economic Review 91, 2001] model of political transitions to show how the anticipation of new loans from international financial institutions can trigger political transitions which would not otherwise have taken place. We test this unexplored implication of the theory empirically. We find in a world sample from 1970 to 2002 that the anticipation of receiving new programs immediately after a political regime transition increases the probability of a transition from autocracy to democracy and reduces the probability of democratic survival
The Higgs boson in the MSSM in light of the LHC
We investigate the expectations for the light Higgs signal in the MSSM in
different search channels at the LHC. After taking into account dark matter and
flavor constraints in the MSSM with eleven free parameters, we show that the
light Higgs signal in the channel is expected to be at most at
the level of the SM Higgs, while the from W fusion
and/or the can be enhanced. For the main discovery
mode, we show that a strong suppression of the signal occurs in two different
cases: low or large invisible width. A more modest suppression is
associated with the effect of light supersymmetric particles. Looking for such
modification of the Higgs properties and searching for supersymmetric partners
and pseudoscalar Higgs offer two complementary probes of supersymmetry.Comment: 19 pages, 8 figure
Ancient mitochondrial pseudogenes reveal hybridization between distant lineages in the evolution of the Rupicapra genus
© The Author(s), 2017. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gene 628 (2017): 63-71, doi:10.1016/j.gene.2017.07.035.Mitochondrial pseudogenes (numts) inserted in the nuclear genome are frequently
found in population studies. Its presence is commonly connected with problems and
errors when they are confounded with true mitochondrial sequences. In the opposite
side, numts can provide valuable phylogenetic information when they are copies of
ancient mitochondrial lineages. We show that Rupicapra individuals of different
geographic origin from the Cantabrian Mountains to the Apennines and the Caucasus
share a nuclear COI fragment. The numt copies are monophyletic, and their pattern of
differentiation shows two outstanding features: a long evolution as differentiated true
mitochondrial lineage, and a recent integration and spread through the chamois
populations. The COI pseudogene is much older than the present day mitochondrial
clades of Rupicapra and occupies a basal position within the Rupicapra-Ammotragus-
Arabitragus node. Joint analysis of this numt and a cytb pseudogene with a similar
pattern of evolution places the source mitochondrial lineage as a sister branch that
separated from the Ammotragus-Arabitragus lineage 6 million years ago (Mya). The
occurrence of this sequence in the nucleus of chamois suggests hybridization between
highly divergent lineages. The integration event seems to be very recent, more recent
than the split of the present day mtDNA lineages of Rupicapra (1.9 Mya). This
observation invites to think of the spread across the genus by horizontal transfer
through recent male-biased dispersal.This work was funded by Ministerio de Economía y Competitividad. Spain. (Grant
number CGL2011-25117).2018-07-1
Probing neutralino dark matter in the MSSM & the NMSSM with directional detection
We investigate the capability of directional detectors to probe neutralino
dark matter in the Minimal Supersymmetric Standard Model and the
Next-to-Minimal Supersymmetric Standard Model with parameters defined at the
weak scale. We show that directional detectors such as the future MIMAC
detector will probe spin dependent dark matter scattering on nucleons that are
beyond the reach of current spin independent detectors. The complementarity
between indirect searches, in particular using gamma rays from dwarf spheroidal
galaxies, spin dependent and spin independent direct search techniques is
emphasized. We comment on the impact of the negative results on squark searches
at the LHC. Finally, we investigate how the fundamental parameters of the
models can be constrained in the event of a dark matter signal.Comment: 21 pages, 16 figure
Anatomy of flower and fruit of Vassobia breviflora (Solanaceae) in the south of the southern Yungas (Argentina)
Solanaceae es una familia con aproximadamente 2400 especies de distribución cosmopolita. Vassobia breviflora es la única especie del género presente en Argentina. El objetivo de este trabajo fue revisar y caracterizar la anatomía de la flor y fruto de V. breviflora a partir de muestras recolectadas en poblaciones de las Yungas del noroeste argentino. Se aplicaron técnicas anatómicas convencionales. Los resultados mostraron que la mayoría de las estructuras de la flor, el fruto y la semilla no difirieron de lo previamente reportado respecto de la organización estructural descripta para otras especies de Solanaceae. No obstante, por primera vez, describimos el androceo, el fruto, la semilla, pedicelo floral y frutal, cinco tipos de tricomas y cinco tipos de estomas en el perianto. Encontramos diferencias en la forma del tejido de transmisión y del tipo de óvulo respecto de lo previamente descripto. Además, localizamos el parénquima y las células epidérmicas secretoras del nectario. En el contexto de la familia Solanaceae, discutimos la función y valor diagnóstico de las estructuras descriptas.Solanaceae is a family with nearly 2400 species of cosmopolitan distribution. Vassobia breviflora is the only species of the genus present in Argentina. The goal of this work was to review and characterize the anatomy of the flower and fruit of V. breviflora from samples collected in populations of Yungas in the argentine Northwest. Conventional anatomical techniques were applied. The results showed that most flower, fruit and seed structures did not differ from those previously reported regarding the structural organization described for other species of the Solanaceae family. However, for the first time, we described the androecium, fruit, seed, floral and fruit pedicels, five types of tricomes and five types of stomata in the perianth. We found some differences in the shape of the transmission tissue and in the type of ovule with respect to that previously reported. Also, we located the parenchyma and the epidermic secretory cells of the nectary. In the context of the family Solanaceae, we discussed the function and diagnostic value of the described structures.Fil: Bernacki, F. G.. Fundación Miguel Lillo; ArgentinaFil: Albornoz, P. L.. Fundación Miguel Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Valoy, M.. Fundación Miguel Lillo; ArgentinaFil: Ordano, Mariano Andrés. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
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