233 research outputs found

    Light-controlled reversible modulation of frontier molecular orbital energy levels in trifluoromethylated diarylethenes

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    Among bistable photochromic molecules, diarylethenes (DAEs) possess the distinct feature that upon photoisomerization they undergo a large modulation of their pelectronic system, accompanied by a marked shift of the HOMO/LUMO energies and hence oxidation/reduction potentials. The electronic modulation can be utilized to remote-control charge-as well as energy-transfer processes and it can be transduced to functional entities adjacent to the DAE core, thereby regulating their properties. In order to exploit such photoswitchable systems it is important to precisely adjust the absolute position of their HOMO and LUMO levels and to maximize the extent of the photoinduced shifts of these energy levels. Here, we present a comprehensive study detailing how variation of the substitution pattern of DAE compounds, in particular using strongly electron-accepting and chemically stable trifluoromethyl groups either in the periphery or at the reactive carbon atoms, allows for the precise tuning of frontier molecular orbital levels over a broad energy range and the generation of photoinduced shifts of more than 1 eV. Furthermore, the effect of different DAE architectures on the transduction of these shifts to an adjacent functional group is discussed. Whereas substitution in the periphery of the DAE motif has only minor implications on the photochemistry, trifluoromethylation at the reactive carbon atoms strongly disturbs the isomerization efficiency. However, this can be overcome by using a nonsymmetrical substitution pattern or by combination with donor groups, rendering the resulting photoswitches attractive candidates for the construction of remote-controlled functional systems

    Consorciação de cana-de-açúcar e canola em clima tropical.

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    Resumo: A consorciação de culturas agrícolas apresenta potencialidade frente ao cenário futuro de escassez de terras agricultáveis e aumento da demanda mundial por alimentos. O desempenho da consorciação de cana-de-açúcar e canola foi avaliado durante três anos em Piracicaba (SP). O experimento foi delineado em blocos casualizados com 4 repetições e 5 tratamentos: cana-de-açúcar + canola Hyola 61; cana-de-açúcar + canola Hyola 401 ou Hyola 571; cana-de-açúcar em monocultivo; canola Hyola 61 monocultivo; canola Hyola 401 ou Hyola 571 monocultivo. A cana-de-açúcar em consórcio com a canola apresentou resultado similar ao seu monocultivo, com produtividade de colmos de 51,0 a 117,0 ton ha-1. A canola consorciada com cana-de-açúcar também apresentou produtividade de grãos similar ao seu monocultivo, de 1.026 a 1.567 kg ha-1. O sistema consorciado resultou em eficiência de uso da terra de 1,74 a 1,87 vezes superior ao monocultivo

    Planar millimeter wave radar frontend for automotive applications

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    A fully integrated planar sensor for 77 GHz automotive applications is presented. The frontend consists of a transceiver multichip module and an electronically steerable microstrip patch array. The antenna feed network is based on a modified Rotman-lens and connected to the array in a multilayer approach offering higher integration. Furthermore, the frontend comprises a phase lock loop to allow proper frequency-modulated continuous wave (FMCW) radar operation. The latest experimental results verify the functionality of this advanced frontend design featuring automatic cruise control, precrash sensing and cut-in detection. These promising radar measurements give reason to a detailed theoretical investigation of system performance. Employing commercially available MMIC various circuit topologies are compared based on signal-tonoise considerations. Different scenarios for both sequential and parallel lobing hint to more advanced sensor designs and better performance. These improvements strongly depend on the availability of suitable MMIC and reliable packaging technologies. Within our present approach possible future MMIC developments are already considered and, thus, can be easily adapted by the flexible frontend design. Es wird ein integrierter planarer Sensor für 77 GHz Radaranwendungen vorgestellt. Das Frontend besteht aus einem Sende- und Empfangs-Multi-Chip-Modul und einer elektronisch schwenkbaren Antenne. Das Speisenetzwerk der Antenne basiert auf einer modifizierten Rotman- Linse. Für eine kompakte Bauweise sind Antenne und Speisenetzwerk mehrlagig integriert. Weiterhin umfasst das Frontend eine Phasenregelschleife für eine präzise Steuerung des frequenzmodulierten Dauerstrichradars. Die aktuellen Messergebnisse bestätigen die Funktionalit¨at dieses neuartigen Frontend-Designs, das automatische Geschwindigkeitsregelung, Kollisionswarnung sowie Nahbereichsüberwachung ermöglicht. Die Qualität der Messergebnisse hat weiterführende theoretische Untersuchungen über die potenzielle Systemleistungsfähigkeit motiviert. Unter Berücksichtigung von kommerziell erhältlichenMMICs werden verschiedene Schaltungstopologien auf der Grundlage des Signal-Rausch-Verhältnisses verglichen. Sowohl für sequenzielle als auch für parallele Ansteuerung der Antennenkeulen wird eine deutliche Leistungssteigerung ermittelt. Diese Verbesserungen hängen maßgeblich von der Verfügbarkeit geeigneter MMICs und einer zuverlässigen Aufbau- und Verbindungstechnik ab. Das vorliegende Frontend-Konzept kann auf Grund seiner Flexibilität leicht an derlei zukünftige Entwicklungen angepasst werden

    Impact of ENSO-related rainfall variability on soybean yield in the state of Rio Grande do Sul, Brazil.

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    Abstract: Rio Grande do Sul (RS) presents a known year-on-year unevenness for soybean production, mainly due to water availability. This study aimed to assess the climate effects, with special focus on rainfall during 25 soybean-growing seasons. Eleven sites were clustered according to soybean yield. The effect of El Niño Southern Oscillation (ENSO) was considered in association with soil water balance. Neutral ENSO phases occurred in 32% of the years, while El Niño and La Ninã in 36% and 32%, respectively. No season presented difference of rainfall among Clusters under Neutral conditions. The limit of 800 mm rainfall for significant yield increments were only achieved in El Niño seasons. The combined effect of rainfall and soil type on soybean yield, represented by the actual soybean yields-water deficit relationship, led to a water cost from -3.7 to -15.2 kg mm-1 ha-1

    Detection of regulator genes and eQTLs in gene networks

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    Genetic differences between individuals associated to quantitative phenotypic traits, including disease states, are usually found in non-coding genomic regions. These genetic variants are often also associated to differences in expression levels of nearby genes (they are "expression quantitative trait loci" or eQTLs for short) and presumably play a gene regulatory role, affecting the status of molecular networks of interacting genes, proteins and metabolites. Computational systems biology approaches to reconstruct causal gene networks from large-scale omics data have therefore become essential to understand the structure of networks controlled by eQTLs together with other regulatory genes, and to generate detailed hypotheses about the molecular mechanisms that lead from genotype to phenotype. Here we review the main analytical methods and softwares to identify eQTLs and their associated genes, to reconstruct co-expression networks and modules, to reconstruct causal Bayesian gene and module networks, and to validate predicted networks in silico.Comment: minor revision with typos corrected; review article; 24 pages, 2 figure

    A perspective on multinational enterprise’s national identity dilemma

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    This conceptual paper identifies gaps and contributes to the literature on ‘identity’ dilemmas faced by multinational enterprises operating in a globalised world. Various characteristics and business strategies of multinational enterprises are delineated and analysed through the lens of social identity theory and international business concepts such as market and institutional logic. Our analysis, based on multiple cases, and derived from a variety of industries and countries, associates the identity dilemma to informed business strategy. Our findings suggest that while multinational enterprises face identity dilemmas that they sometimes use to their advantage, it also poses several challenges. Through our conceptualisation, we derive five distinct propositions to shape future research directions

    Promoter-anchored chromatin interactions predicted from genetic analysis of epigenomic data

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    Promoter-anchored chromatin interactions (PAIs) play a pivotal role in transcriptional regulation. Current high-throughput technologies for detecting PAIs, such as promoter capture Hi-C, are not scalable to large cohorts. Here, we present an analytical approach that uses summary-level data from cohort-based DNA methylation (DNAm) quantitative trait locus (mQTL) studies to predict PAIs. Using mQTL data from human peripheral blood ([Formula: see text]), we predict 34,797 PAIs which show strong overlap with the chromatin contacts identified by previous experimental assays. The promoter-interacting DNAm sites are enriched in enhancers or near expression QTLs. Genes whose promoters are involved in PAIs are more actively expressed, and gene pairs with promoter-promoter interactions are enriched for co-expression. Integration of the predicted PAIs with GWAS data highlight interactions among 601 DNAm sites associated with 15 complex traits. This study demonstrates the use of mQTL data to predict PAIs and provides insights into the role of PAIs in complex trait variation

    Foreign direct investment and institutional reform : evidence and an application to Portugal

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    We examine the role of geographic, economic, and institutional factors in attracting Foreign Direct Investment (FDI) in Europe, using a cross-section of inward bilateral investments. We estimate and assess the expected benefits, the required reform efforts, and the efficiency of reform options corresponding to a con- vergence of Portuguese institutions to EU standards. We conclude that improving home institutions is likely to have a quantitatively very significant role in attracting FDI. Geographical and market size factors also play a role. Reforms promoting the independence of financial institutions and a leaner bureaucracy, lowering political risk and corruption, and improving the investment code may significantly affect the amount of bilateral inward FDI that is targeted to Portugal.info:eu-repo/semantics/publishedVersio

    Integrative analysis of omics summary data reveals putative mechanisms underlying complex traits

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    The identification of genes and regulatory elements underlying the associations discovered by GWAS is essential to understanding the aetiology of complex traits (including diseases). Here, we demonstrate an analytical paradigm of prioritizing genes and regulatory elements at GWAS loci for follow-up functional studies. We perform an integrative analysis that uses summary-level SNP data from multi-omics studies to detect DNA methylation (DNAm) sites associated with gene expression and phenotype through shared genetic effects (i.e., pleiotropy). We identify pleiotropic associations between 7858 DNAm sites and 2733 genes. These DNAm sites are enriched in enhancers and promoters, and >40% of them are mapped to distal genes. Further pleiotropic association analyses, which link both the methylome and transcriptome to 12 complex traits, identify 149 DNAm sites and 66 genes, indicating a plausible mechanism whereby the effect of a genetic variant on phenotype is mediated by genetic regulation of transcription through DNAm
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