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We propose a new approach to portfolio optimization that utilizes a unique combination of synthetic data generation and a CVaR-constraint. We formulate the portfolio optimization problem as an asset allocation problem in which each asset class is accessed through a passive (index) fund. The asset-class weights are determined by solving an optimization problem which includes a CVaR-constraint. The optimization is carried out by means of a Modified CTGAN algorithm which incorporates features (contextual information) and is used to generate synthetic return scenarios, which, in turn, are fed into the optimization engine. For contextual information, we rely on several points along the U.S. Treasury yield curve. The merits of this approach are demonstrated with an example based on 10 asset classes (covering stocks, bonds, and commodities) over a fourteen-and-half-year period (January 2008–June 2022). We also show that the synthetic generation process is able to capture well the key characteristics of the original data, and the optimization scheme results in portfolios that exhibit satisfactory out-of-sample performance. We also show that this approach outperforms the conventional equal-weights (1/N) asset allocation strategy and other optimization formulations based on historical data only. [ABSTRACT FROM AUTHOR]

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This article assesses the use of under-vine living mulches in Mediterranean vineyards characterized by limited water resources, one of the reasons why this agronomic practice is currently unusual in these environments. The aim of the study was to test whether the use of this alternative method in Mediterranean vineyards could suppress noxious weeds without hindering optimal vineyard development. For this purpose, four native species were selected as living mulches: Festuca ovina, Pilosella officinarum, Plantago coronopus, and Plantago lanceolata. The variables measured during three years in two different experimental farms were: (a) living mulch cover, as a possible predictor of weed suppression success; (b) weed density and weed biomass, with special attention to noxious weed species; and (c) pruning weights, measured in the last year to analyze the cumulative effect of the treatments on the grapevine vegetative growth. Our results revealed that living mulches with high cover rates (average over 70%) also showed weed suppression of up to 95%, significantly controlling the occurrence of noxious weeds such as Erigeron canadensis. No significant effect of the different treatments on vine vegetative growth was found, although further studies would be necessary. Based on these findings, it can be concluded that under-vine living mulches could be an efficient and environmentally friendly method for weed control in Mediterranean vineyards where irrigation is available. [ABSTRACT FROM AUTHOR]

The perennial and stoloniferous weed, Cynodon dactylon (L.) Pers. (bermudagrass), is a serious problem in vineyards. The spectral similarity between bermudagrass and grapevines makes discrimination of the two species, based solely on spectral information from multi-band imaging sensor, unfeasible. However, that challenge can be overcome by use of object-based image analysis (OBIA) and ultra-high spatial resolution Unmanned Aerial Vehicle (UAV) images. This research aimed to automatically, accurately, and rapidly map bermudagrass and design maps for its management. Aerial images of two vineyards were captured using two multispectral cameras (RGB and RGNIR) attached to a UAV. First, spectral analysis was performed to select the optimum vegetation index (VI) for bermudagrass discrimination from bare soil. Then, the VI-based OBIA algorithm developed for each camera automatically mapped the grapevines, bermudagrass, and bare soil (accuracies greater than 97.7%). Finally, site-specific management maps were generated. Combining UAV imagery and a robust OBIA algorithm allowed the automatic mapping of bermudagrass. Analysis of the classified area made it possible to quantify grapevine growth and revealed expansion of bermudagrass infested areas. The generated bermudagrass maps could help farmers improve weed control through a well-programmed strategy. Therefore, the developed OBIA algorithm offers valuable geo-spatial information for designing site-specific bermudagrass management strategies leading farmers to potentially reduce herbicide use as well as optimize fuel, field operating time, and costs. [ABSTRACT FROM AUTHOR]

Abstract The regulation of gene expression through the cell wall integrity (CWI) pathway in yeast is mainly coordinated by the MAPK Slt2 and the transcription factor Rlm1. In this work, we elucidate a new role for Slt2 as a part of the transcriptional activation machinery that regulates CWI gene expression in response to cell wall stress. We show that Slt2 is recruited to promoters and coding regions of CWI Rlm1-dependent genes in response to stress. This phenomenon is dependent both on the activation of the MAPK and its kinase activity. Slt2 binding is also dependent on Rlm1 and SWI/SNF and SAGA complexes. During the initial steps of transcription, the catalytic activity of Slt2 on Rlm1 is critical for the binding of the activator to promoters in response to stress. In addition, Slt2 itself acts as a transactivator, as it is able to induce the transcription of CWI responsive genes when it is bound to promoters through the Rlm1 binding domain independently of its catalytic activity. Slt2 interacts with RNA Pol II in a Rlm1-dependent manner to provide further support to a role of this MAPK as an integral component of the transcriptional complexes under cell wall stress. Selective recruitment and progression of the complex Slt2-RNA Pol II from the promoters to the coding regions of Rlm1-dependent genes does not rely on Paf1, suggesting a different mechanism from that which is exerted by Slt2 on the Swi4/Swi6 (SBF)-regulated genes. Highlights • Slt2 is part of the transcriptional activation machinery. • Slt2 binds to CWI-responsive genes in a Rlm1, Snf2 and Gcn5-dependent manner. • Slt2 mediates catalytic and non-catalytic mechanisms to activate transcription. • Slt2 mediates the recruitment of the RNA Pol II to Rlm1-dependent genes. • Slt2-RNA Pol II progression along Rlm1-dependent genes does not rely on Paf1. [ABSTRACT FROM AUTHOR]

Addressing the spatial and temporal variability of crops for agricultural management requires intensive and periodical information gathering from the crop fields. Unmanned Aerial Vehicle (UAV) photogrammetry is a quick and affordable method for information collecting; it provides spectral and spatial information when required with the added value of Digital Surface Models (DSMs) that reconstruct the crop structure in 3D using 'structure from motion' techniques. In the full process from UAV flights to image analysis, DSM generation is one bottle-neck due to its high processing time. Despite its importance, the optimization of the required forward overlap for saving time in DSM generation has not yet been studied. UAV images were acquired at 50 and 100 m flight altitudes over two olive orchards with the aim of generating DSMs representing the tree crowns. Several DSMs created with different forward laps (in intervals of 5-6% from 58 to 97%) were evaluated in order to determine the optimal generation time according to the accuracy of tree crown measurements computed from each DSM. Based on our results, flying at 100 m altitude and with a 95% forward lap reported the best configuration. From the analysis derived from this configuration, tree volume was estimated with 95% accuracy. In addition, computing time was 85% lower in comparison to the maximum overlap studied (97%). It allowed computing the 3D features of 600 trees in a 3-ha parcel in a highly accurate and quick (a few hours after the UAV flights) manner by using a standard computer. [ABSTRACT FROM AUTHOR]

Activation of the yeast cell wall integrity (CWI) pathway induces an adaptive transcriptional programme that is largely dependent on the transcription factor Rlm1 and the mitogen-activated protein kinase (MAPK) Slt2. Upon cell wall stress, the transcription factor Rlm1 is recruited to the promoters of RLM1 and SLT2, and exerts positivefeedback mechanisms on the expression of both genes. Activation of the MAPK Slt2 by cell wall stress is not impaired in strains with individual blockade of any of the two feedback pathways. Abrogation of the autoregulatory feedback mechanism on RLM1 severely affects the transcriptional response elicited by activation of the CWI pathway. In contrast, a positive trans-acting feedback mechanism exerted by Rlm1 on SLT2 also regulates CWI output responses but to a lesser extent. Therefore, a complete CWI transcriptional response requires not only phosphorylation of Rlm1 by Slt2 but also concurrent SLT2- and RLM1-mediated positive-feedback mechanisms; sustained patterns of gene expression are mainly achieved by positive autoregulatory circuits based on the transcriptional activation of Rlm1. [ABSTRACT FROM AUTHOR]

Background: The fungal cell wall forms a compact network whose integrity is essential for cell morphology and viability. Thus, fungal cells have evolved mechanisms to elicit adequate adaptive responses when cell wall integrity (CWI) is compromised. Functional genomic approaches provide a unique opportunity to globally characterize these adaptive mechanisms. To provide a global perspective on these CWI regulatory mechanisms, we developed chemical-genomic profiling of haploid mutant budding yeast cells to systematically identify in parallel those genes required to cope with stresses interfering the cell wall by different modes of action: β-1,3 glucanase and chitinase activities (zymolyase), inhibition of β-1,3 glucan synthase (caspofungin) and binding to chitin (Congo red). Results: Measurement of the relative fitness of the whole collection of 4786 haploid budding yeast knock-out mutants identified 222 mutants hypersensitive to caspofungin, 154 mutants hypersensitive to zymolyase, and 446 mutants hypersensitive to Congo red. Functional profiling uncovered both common and specific requirements to cope with different cell wall damages. We identified a cluster of 43 genes highly important for the integrity of the cell wall as the common "signature of cell wall maintenance (CWM)". This cluster was enriched in genes related to vesicular trafficking and transport, cell wall remodeling and morphogenesis, transcription and chromatin remodeling, signal transduction and RNA metabolism. Although the CWI pathway is the main MAPK pathway regulating cell wall integrity, the collaboration with other signal transduction pathways like the HOG pathway and the invasive growth pathway is also required to cope with the cell wall damage depending on the nature of the stress. Finally, 25 mutant strains showed enhanced caspofungin resistance, including 13 that had not been previously identified. Only three of them, wsc1Δ, elo2Δ and elo3Δ, showed a significant decrease in β-1,3-glucan synthase activity. Conclusions: This work provides a global perspective about the mechanisms involved in cell wall stress adaptive responses and the cellular functions required for cell wall integrity. The results may be useful to uncover new potential antifungal targets and develop efficient antifungal strategies by combination of two drugs, one targeting the cell wall and the other interfering with the adaptive mechanisms. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) combined with different spectral range sensors are an emerging technology for providing early weed maps for optimizing herbicide applications. Considering that weeds, at very early phenological stages, are similar spectrally and in appearance, three major components are relevant: spatial resolution, type of sensor and classification algorithm. Resampling is a technique to create a new version of an image with a different width and/or height in pixels, and it has been used in satellite imagery with different spatial and temporal resolutions. In this paper, the efficiency of resampled-images (RS-images) created from real UAV-images (UAV-images; the UAVs were equipped with two types of sensors, i.e., visible and visible plus near-infrared spectra) captured at different altitudes is examined to test the quality of the RS-image output. The performance of the object-based-image-analysis (OBIA) implemented for the early weed mapping using different weed thresholds was also evaluated. Our results showed that resampling accurately extracted the spectral values from high spatial resolution UAV-images at an altitude of 30 m and the RS-image data at altitudes of 60 and 100 m, was able to provide accurate weed cover and herbicide application maps compared with UAV-images from real flights. [ABSTRACT FROM AUTHOR]

A procedure named CROPCLASS was developed to semi-automate census parcel crop assessment in any agricultural area using multitemporal remote images. For each area, CROPCLASS consists of a) a definition of census parcels through vector files in all of the images; b) the extraction of spectral bands (SB) and key vegetation index (VI) average values for each parcel and image; c) the conformation of a matrix data (MD) of the extracted information; d) the classification of MD decision trees (DT) and Structured Query Language (SQL) crop predictive model definition also based on preliminary land-use ground-truth work in a reduced number of parcels; and e) the implementation of predictive models to classify unidentified parcels land uses. The software named CROPCLASS-2.0 was developed to semi-automatically perform the described procedure in an economically feasible manner. The CROPCLASS methodology was validated using seven GeoEye-1 satellite images that were taken over the LaVentilla area (Southern Spain) from April to October 2010 at 3- to 4-week intervals. The studied region was visited every 3 weeks, identifying 12 crops and others land uses in 311 parcels. The DT training models for each cropping system were assessed at a 95% to 100% overall accuracy (OA) for each crop within its corresponding cropping systems. The DT training models that were used to directly identify the individual crops were assessed with 80.7% OA, with a user accuracy of approximately 80% or higher for most crops. Generally, the DT model accuracy was similar using the seven images that were taken at approximately one-month intervals or a set of three images that were taken during early spring, summer and autumn, or set of two images that were taken at about 2 to 3 months interval. The classification of the unidentified parcels for the individual crops was achieved with an OA of 79.5%. [ABSTRACT FROM AUTHOR]

Living cells exposed to stressful environmental situations can elicit cellular responses that guarantee maximal cell survival. Most of these responses are mediated by mitogen-activated protein kinase (MAPK) cascades, which are highly conserved from yeast to humans. Cell wall damage conditions in the yeast Saccharomyces cerevisiae elicit rescue mechanisms mainly associated with reprogramming specific transcriptional responses via the cell wall integrity (CWI) pathway. Regulation of gene expression by this pathway is coordinated by the MAPK Slt2/Mpk1, mainly via Rlm1 and, to a lesser extent, through SBF (Swi4/Swi6) transcription factors. In this review, we summarize the molecular mechanisms controlling gene expression upon cell wall stress and the role of chromatin structure in these processes. Some of these mechanisms are also discussed in the context of other stresses governed by different yeast MAPK pathways. Slt2 regulates both transcriptional initiation and elongation by interacting with chromatin at the promoter and coding regions of CWI-responsive genes but using different mechanisms for Rlm1- and SBF-dependent genes. Since MAPK pathways are very well conserved in eukaryotic cells and are essential for controlling cellular physiology, improving our knowledge regarding how they regulate gene expression could impact the future identification of novel targets for therapeutic intervention. [ABSTRACT FROM AUTHOR]

The multigene GAS family of Saccharomyces cerevisiae is constituted by five genes encoding GPI-anchored proteins required for cell wall or spore wall assembly. GAS1 and GAS5 are expressed in vegetative growth and repressed during sporulation, whereas GAS2 and GAS4 exhibit the opposite expression pattern. This study focuses on GAS3, a still poorly characterized member of the family. To date, attempts to reveal the glucan elongase activity typical of Gas proteins have been unsuccessful, suggesting that Gas3p is the only inactive member of the family. Here, we compared the mRNA levels of GAS1, GAS3 and GAS5 and demonstrate that GAS3 is the weakest-expressed paralogue in vegetative growth. Moreover, GAS3 mRNA increased during sporulation, showing a bimodal profile typical of the early-middle meiotic genes. GAS3 product was identified as a low-abundance, polydisperse mannoprotein. Loss of Gas3p did not affect growth and sporulation. The overexpression of GAS3, driven by the GAS1 promoter, slightly reduced growth rate in a wild-type strain and led to hyperaccumulation of Gas3p in the membranes and in the cell wall. To determine whether GAS3 could replace GAS1 function in vivo, GAS3 was also overexpressed in a gas1Δ mutant. Increased amounts of Gas3p were not only unable to complement the defects of the gas1Δ cells but exacerbated them. A mutated Gas3p-E283Q, where one of the catalytic glutamate residues essential for GH72 enzyme activity was replaced by glutamine, was also noxious to gas1Δ cells, indicating that the increased expression of Gas3p, rather than a potential activity, is deleterious for gas1Δ cells. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The cell wall is the first interface between a fungus and its extracellular environment. Glycosyltransferases involved in the formation and dynamic remodelling of the polysaccharide network of the cell wall have recently been identified. The best characterized ones belong to the Gas family, which elongates β(1,3)-glucans, and to the Crh family, which are involved in the cross-linking of chitin to β(1,6)-glucan. All these proteins carry a glycosylphosphatidylinositol (GPI) anchor. In this work, we show that recombinant soluble forms of Gas1-5 and Crh1p from Saccharomyces cerevisiae and their orthologous proteins Gel1-Gel2 and Crf1 from Aspergillus fumigatus are specifically recognized by antibodies present in the sera of patients with Aspergillus or Candida infections. Quantification of the antibody titres against recombinant Gas/Gel and Crh/Crf proteins separated aspergilloma and candidiasis patients from non-infected individuals. Cross-reactivity was seen between the antibody response of patients with aspergillosis and candidiasis towards the Gas/Gel and Crh/Crf proteins. These results suggest that GPI-anchored cross-linking enzymes are relevant immunologically reactive constituents of the cell wall that may play a role during human fungal infections. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the spatial persistence of wild oat patches in four wheat fields over time to determine the economic feasibility of using late-season wild oat maps for early site-specific weed management (SSWM) next season. The spatial persistence of wild oat patches was analyzed by three tests: land use change detection between years, spatial autocorrelation, and analysis of spreading distance. The temporal trend of wild oat patch distribution showed a clear persistence and a generalized increase in the infested area, with a noticeable level of weed aggregation and a tendency in the new weed patches to emerge close to older ones. To economically evaluate the SSWM, five simulations in four agronomic scenarios, varying wheat yields and losses due to wild oat, were conducted. When yield losses due to wild oat were minimal and for any of the expected wheat yields, some SSWM simulations were more economically profitable than the overall application in most of the fields. Nevertheless, when the yield losses due to wild oat were maximal, all SSWM simulations were less profitable than overall treatment in all the analyzed fields. Although the economic profit variations achieved with SSWM treatments were modest, any of the site-specific treatments tested are preferred to herbicide broadcast over the entire field, in order to reduce herbicide and environmental pollution. [ABSTRACT FROM AUTHOR]

The use of remote imagery captured by unmanned aerial vehicles (UAV) has tremendous potential for designing detailed site-specific weed control treatments in early post-emergence, which have not possible previously with conventional airborne or satellite images. A robust and entirely automatic object-based image analysis (OBIA) procedure was developed on a series of UAV images using a six-band multispectral camera (visible and near-infrared range) with the ultimate objective of generating a weed map in an experimental maize field in Spain. The OBIA procedure combines several contextual, hierarchical and object-based features and consists of three consecutive phases: 1) classification of crop rows by application of a dynamic and auto-adaptive classification approach, 2) discrimination of crops and weeds on the basis of their relative positions with reference to the crop rows, and 3) generation of a weed infestation map in a grid structure. The estimation of weed coverage from the image analysis yielded satisfactory results. The relationship of estimated versus observed weed densities had a coefficient of determination of r2=0.89 and a root mean square error of 0.02. A map of three categories of weed coverage was produced with 86% of overall accuracy. In the experimental field, the area free of weeds was 23%, and the area with low weed coverage (<5% weeds) was 47%, which indicated a high potential for reducing herbicide application or other weed operations. The OBIA procedure computes multiple data and statistics derived from the classification outputs, which permits calculation of herbicide requirements and estimation of the overall cost of weed management operations in advance. [ABSTRACT FROM AUTHOR]

The regulation of gene expression through the cell wall integrity (CWI) pathway in yeast is mainly coordinated by the MAPK Slt2 and the transcription factor Rlm1. In this work, we elucidate a new role for Slt2 as a part of the transcriptional activation machinery that regulates CWI gene expression in response to cell wall stress. We show that Slt2 is recruited to promoters and coding regions of CWI Rlm1-dependent genes in response to stress. This phenomenon is dependent both on the activation of the MAPK and its kinase activity. Slt2 binding is also dependent on Rlm1 and SWI/SNF and SAGA complexes. During the initial steps of transcription, the catalytic activity of Slt2 on Rlm1 is critical for the binding of the activator to promoters in response to stress. In addition, Slt2 itself acts as a transactivator, as it is able to induce the transcription of CWI responsive genes when it is bound to promoters through the Rlm1 binding domain independently of its catalytic activity. Slt2 interacts with RNA Pol II in a Rlm1-dependent manner to provide further support to a role of this MAPK as an integral component of the transcriptional complexes under cell wall stress. Selective recruitment and progression of the complex Slt2-RNA Pol II from the promoters to the coding regions of Rlm1-dependent genes does not rely on Paf1, suggesting a different mechanism from that which is exerted by Slt2 on the Swi4/Swi6 (SBF)-regulated genes., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In budding yeast, chitin is found in three locations: at the primary septum, largely in free form, at the mother-bud neck, partially linked to beta(1-3)glucan, and in the lateral wall, attached in part to beta(1-6)glucan. By using a recently developed strategy for the study of cell wall cross-links, we have found that chitin linked to beta(1-6)glucan is diminished in mutants of the CRH1 or the CRH2/UTR2 gene and completely absent in a double mutant. This indicates that Crh1p and Crh2p, homologues of glycosyltransferases, ferry chitin chains from chitin synthase III to beta(1-6)glucan. Deletion of CRH1 and/or CRH2 aggravated the defects of fks1Delta and gas1Delta mutants, which are impaired in cell wall synthesis. A temperature shift from 30 degrees C to 38 degrees C increased the proportion of chitin attached to beta(1-6)glucan. The expression of CRH1, but not that of CRH2, was also higher at 38 degrees C in a manner dependent on the cell integrity pathway. Furthermore, the localization of both Crh1p and Crh2p at the cell cortex, the area where the chitin-beta(1-6)glucan complex is found, was greatly enhanced at 38 degrees C. Crh1p and Crh2p are the first proteins directly implicated in the formation of cross-links between cell wall components in fungi.

The GAS multigene family of Saccharomyces cerevisiae is composed of five paralogs (GAS1 to GAS5). GAS1 is the only one of these genes that has been characterized to date. It encodes a glycosylphosphatidylinositol-anchored protein functioning as a beta(1,3)-glucan elongase and required for proper cell wall assembly during vegetative growth. In this study, we characterize the roles of the GAS2 and GAS4 genes. These genes are expressed exclusively during sporulation. Their mRNA levels showed a peak at 7 h from induction of sporulation and then decreased. Gas2 and Gas4 proteins were detected and reached maximum levels between 8 and 10 h from induction of sporulation, a time roughly coincident with spore wall assembly. The double null gas2 gas4 diploid mutant showed a severe reduction in the efficiency of sporulation, an increased permeability of the spores to exogenous substances, and production of inviable spores, whereas the single gas2 and gas4 null diploids were similar to the parental strain. An analysis of spore ultrastructure indicated that the loss of Gas2 and Gas4 proteins affected the proper attachment of the glucan to the chitosan layer, probably as a consequence of the lack of coherence of the glucan layer. The ectopic expression of GAS2 and GAS4 genes in a gas1 null mutant revealed that these proteins are redundant versions of Gas1p specialized to function in a compartment at a pH value close to neutral.