11,880 research outputs found
Combinatorial Penalties: Which structures are preserved by convex relaxations?
We consider the homogeneous and the non-homogeneous convex relaxations for
combinatorial penalty functions defined on support sets. Our study identifies
key differences in the tightness of the resulting relaxations through the
notion of the lower combinatorial envelope of a set-function along with new
necessary conditions for support identification. We then propose a general
adaptive estimator for convex monotone regularizers, and derive new sufficient
conditions for support recovery in the asymptotic setting
Maritime pine PpMYB8 directly co-regulates secondary cell wall architecture and the associated Phe-biosynthesis pathway
Plants rely on the biosynthesis of L-Phenylalanine as building block for the synthesis of
proteins but also as precursor for a tremendous range of plant-derived compounds
essential for its grown, development and defense. Polymerization of secondary cell wall
in trees involves the massive biosynthesis, among others, of the Phe-derived compound
lignin. Thus, these plants require an accurate metabolic coordination between Phe and
lignin biosynthesis to ensure its normal development. We have here identified that the
pine arogenate dehydratase, whose enzyme activity limits the biosynthesis of Phe in
plants, is transcriptionally regulated through direct interaction with PpMyb8. We have
also shown that this transcription factor is directly involve in secondary cell wall
biogenesis and cell death processes. Together these results indicate that a single
transcription factor coordinates lignin accumulation and the proper biosynthesis of its
essential precursor L-Phe.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
The Application of Building Modifications and their Effects on Energy Consumption in Buildings
A huge amount of energy is used for air-conditioning in residential buildings in hot climates. Passive design features such as shading and advanced glazing can help to reduce energy use and carbon emissions, and thus mitigate the impact on climate change. This paper aimed at demonstrating how the application of selected modification devices such as solar films and shading devices affects the energy consumption patterns and levels in a residential building. A model of a building was constructed with VE using “Model IT” module, which was then analysed in a variety of different ways. A Virtual Integrated Environmental Solutions (IES-VE) was used to assess the energy gain and consumption parameters such as solar gains, shading devices, solar cloud and chilli clouds in residential buildings in Tripoli, Libya. The findings indicate that the best way to control and reduce the energy gains pattern in a building is to introduce energy modification devices such as shading device, solar films, emissivity paints and roof slab absorbers among others. In specific terms, the best device would be the application of external solar film, follow by shading device and internal solar film. An application of emissivity paints and roof slab absorbers does not contribute significantly to the energy reduction in the building. The study concludes that the application of modification devices in buildings can reduces the heat gain significantly. This study underscores the need and importance of the applications of energy modification devices in buildings in order to reduce their energy gains in the context of tropical regions. Though the climatological characteristics of tropical regions are similar, the generalisation of the findings in this study requires caution since the findings are limited in geographical context. Future research should also explore the impact of urban forms, street layout and orientation on solar penetration and energy use in buildings. Keywords: Architecture, Buildings, Climate change, Energy consumption, Energy gains, Liby
Beyond the barrier: Female Genital Schistosomiasis as a potential risk factor for HIV-1 acquisition.
Female genital schistosomiasis (FGS) results from egg-deposition in the female reproductive tract primarily by the waterborne parasite Schistosoma (S.) haematobium, and less commonly by Schistosoma (S.) mansoni. FGS affects an estimated 20-56 million women worldwide, mostly in sub-Saharan Africa. There is cross-sectional evidence of increased HIV-1 prevalence in schistosomiasis-infected women, but a causal relationship between FGS and either HIV-1 acquisition or transmission has not been fully established. Beyond the pathognomonic breach in the cervicovaginal barrier caused by FGS, this narrative review explores potential mechanisms for a synergistic relationship between S. haematobium infection, FGS, and HIV-1 acquisition through vaginal inflammation and target cell recruitment
Metabolic channeling of phe for lignin biosynthesis in maritime pine
Phenylalanine (Phe) is the main precursor of phenylpropanoids biosynthesis in plants. This vast family of Phe-derived compounds can represent more than 30% of captured photosynthetic carbon, playing essential roles in plants such as cell wall components, defense molecules, pigments and flavors. In addition to its physiological importance, phenylpropanoids and particularly lignin, a component of wood, are targets in plant biotechnology.
The arogenate pathway has been proposed as the main pathway for Phe biosynthesis in plants (Maeda et al., 2010). The final step in Phe biosynthesis, catalyzed by the enzyme arogenate dehydratase (ADT), has been considered as a key regulatory point in Phe biosynthesis, due to its key branch position in the pathway, the multiple isoenzymes identified in plants and the existence of a feedback inhibition mechanism by Phe. So far, the regulatory mechanisms underlying ADT genes expression have been poorly characterized, although a strong regulation of the Phe metabolic flux should be expected depending on its alternative use for protein biosynthesis versus phenylpropanoid biosynthesis. This second fate involves a massive carbon flux compared to the first one.
Here we report our current research activities in the transcriptional regulation of ADT genes by MYB transcription factors in Pinus pinaster. The conifers channels massive amounts of photosynthetic carbon for phenylpropanoid biosynthesis during wood formation. We have identified the complete ADT gene family in maritime pine (El-Azaz et al., 2016) and a set of ADT isoforms specifically related with the lignification process. The potential control of transcription factors previously reported as key regulators in pine wood formation (Craven-Bartle et al., 2013) will be presented.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Highly transparent low capacitance plasma enhanced atomic layer deposition Al2O3-HfO2 tunnel junction engineering
Abstract : The development of metallic single electron transistor (SET) depends on the downscaling and the electrical properties of its tunnel junctions. These tunnel junctions should insure high tunnel current levels, low thermionic current, and low capacitance. The authors use atomic layer deposition to fabricate Al2O3 and HfO2 thin layers. Tunnel barrier engineering allows the achievement of low capacitance Al2O3 and HfO2 tunnel junctions using optimized annealing and plasma exposure conditions. Different stacks were designed and fabricated to increase the transparency of the tunnel junction while minimizing thermionic current. This tunnel junction is meant to be integrated in SET to enhance its electrical properties (e.g., operating temperature, ION/IOFF ratio)
Granulopoiesis inhibition in acute inflammation: comparative studies in healthy and leukaemic mice
It was demonstrated previously that mice undergoing an inflammatory reaction induced by subcutaneous (SC) implantation of copper rods, produce humoral factors that initially enhance, but subsequently inhibit, diffusion chamber (DC) granulopoiesis. This provided evidence that granulopoiesis is under the control of both humoral stimulators and inhibitors. In order to test the granulopoietic regulatory mechanism in leukaemic mice, we investigated the regulatory role of granulopoietic humoral inhibitors during in vivo granulopoiesis. We noticed that mice suffering from acute myeloid leukaemia (AML) are unable to augment the production of these humoral inhibitory factors when acute inflammation is induced, since no change in DC cell content was observed with or without prior inflammation. Moreover, unlike healthy mice, the serum of leukaemic mice withdrawn during the inhibition phase of acute inflammation did not show any inhibitory activity toward granulocyte—monocyte (GM) colony growth in vitro. Our results also show that increased levels of normal humoral inhibitors do not influence the proliferation and/or differentiation of leukaemic cells implanted in diffusion chamber cultures
Immunoglobulin-A and the pathogenesis of schistosomal glomerulopathy
Immunoglobin-A and the pathogenesis of schistosomal glomerulopathy. Several observations suggest that the evolution of schistosomal glomerulopathy into clinically overt and progressive disease may involve pathogenetic mechanisms other than simple glomerular deposition of parasitic antigens. In a previous study, IgA was suggested tobe a mediator of late glomerular lesions in this disease. This issue is further addressed in this work. The study includes 32 patients with hepatosplenic schistosomiasis, of whom 16 had overt glomerular involvement, along with four control groups: (a) 15 healthy volunteers; (b) 15 patients with simple intestinal mansoniasis; (c) 17 patients with non-schistosomal chronic liver disease; and (d) 21 subjects with primary nephrotic syndrome not associated with schistosomiasis. Routine assessment was done for all subjects including confirmatory tests for schistosomal infection, liver and renal function tests, hepatitis viral markers and abdominal ultrasonography. The total serum concentrations of IgG, IgM, IgA were measured, as well astheir respective circulating immune complexes, rheumatoid factors, anti-gliadin- and anti-DNA-antibodies. Liver and renal biopsies were obtained from the relevant groups and studied by light microscopy. Renal biopsies were also examined by immunofluorescence. Patients with simple intestinal schistosomiasis had a significant increase in IgM antigliadin antibodies. Those complicated with hepatosplenic involvement also had a significant increase in the mean IgG anti-gliadin antibodies, IgG rheumatoid factor and IgM anti-DNA activity. Cases further complicated by overt glomerular disease showed a distinct IgA predominance, mainly expressed in the serum anti-gliadin antibody pool and anti-DNA activity. This profile was essentially similar to that observed in control cirrhotics. There was a significant increase in the frequency of IgA glomerular deposits in renal biopsies obtained from patients with overt schistosomal glomerulopathy, in contrast to control nephrotics. The deposits were mainly mesangial, but were also encountered in subendothelial, subepithelial and peritubular locations. Their frequency was significantly higher with more advanced lesions as seen by light microscopy. The relevance of these data is discussed, leading to the following conclusions: (a) serum IgA-anti-gliadin and -anti-DNA antibodies, and glomerular IgA deposits are markers of significant renal involvement in patients with hepatosplenic schistosomiasis, (b) IgA may be involved in the pathogenesis of advanced glomerular pathology when superimposed on parasite-induced lesions, (c) There is a significant increase in serum auto-reactivity in hepatosplenic schistosomiasis, which may also have pathogentic implications, (d) Increased production by the inflammatory bowel lesions, impaired clearance by the fibrotic livers and probable switching of immunoglobulin synthesis are suggested to explain the observed IgA predominance in those who develop renal complications
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