Molecular-assisted selection for resistance to cassava mosaic disease in Manihot esculenta Crantz

The geminivirus complex known as cassava mosaic disease (CMD) is one of the most devastating viruses for cassava (Manihot esculenta Crantz). The aim of this study was to use molecular-assisted selection (MAS) to identify CMD-resistant accessions and ascertain promising crosses with elite Brazilian varieties. One thousand two hundred twenty-four accessions were genotyped using five molecular markers (NS169, NS158, SSRY028, SSRY040 and RME1) that were associated with resistance to CMD, along with 402 SNPs (single-nucleotide polymorphism). The promising crosses were identified using a discriminant analysis of main component (DAPC), and the matrix of genomic relationship was estimated with SNP markers. The CMD1 gene, previously described in M. glaziovii, was not found in M. esculenta. In contrast, the CMD2 gene was found in 5, 4 and 5 % of cassava accessions, with flanking markers NS169+RME1, NS158+RME1 and SSRY28+RME1, respectively. Only seven accessions presented all markers linked to the CMD resistance. The DAPC of the seven accessions along with 17 elite cassava varieties led to the formation of three divergent clusters. Potential sources of resistance to CMD were divided into two groups, while the elite varieties were distributed into three groups. The low estimates of the genomic relationship (ranging from -0.167 to 0.681 with an average of 0.076) contributed to the success in identifying contrasting genotypes. The use of MAS in countries where CMD is a quarantine disease constitutes a successful strategy not only for identifying the resistant accessions but also for determining the promising crosses

Towards an integrated set of surface meteorological observations for climate science and applications

Observations are the foundation for understanding the climate system. Yet, currently available land meteorological data are highly fractured into various global, regional and national holdings for different variables and timescales, from a variety of sources, and in a mixture of formats. Added to this, many data are still inaccessible for analysis and usage. To meet modern scientific and societal demands as well as emerging needs such as the provision of climate services, it is essential that we improve the management and curation of available land-based meteorological holdings. We need a comprehensive global set of data holdings, of known provenance, that is truly integrated both across Essential Climate Variables (ECVs) and across timescales to meet the broad range of stakeholder needs. These holdings must be easily discoverable, made available in accessible formats, and backed up by multi-tiered user support. The present paper provides a high level overview, based upon broad community input, of the steps that are required to bring about this integration. The significant challenge is to find a sustained means to realize this vision. This requires a long-term international program. The database that results will transform our collective ability to provide societally relevant research, analysis and predictions in many weather and climate related application areas across much of the globe

Hydroxide films on mica form charge-stabilized microphases that circumvent nucleation barriers

Crystal nucleation is facilitated by transient, nanoscale fluctuations that are extraordinarily difficult to observe. Here, we use high-speed atomic force microscopy to directly observe the growth of an aluminum hydroxide film from an aqueous solution and characterize the dynamically fluctuating nanostructures that precede its formation. Nanoscale cluster distributions and fluctuation dynamics show many similarities to the predictions of classical nucleation theory, but the cluster energy landscape deviates from classical expectations. Kinetic Monte Carlo simulations show that these deviations can arise from electrostatic interactions between the clusters and the underlying substrate, which drive microphase separation to create a nanostructured surface phase. This phase can evolve seamlessly from a low-coverage state of fluctuating clusters into a high-coverage nanostructured network, allowing the film to grow without having to overcome classical nucleation barriers

Comparison of disease patterns assessed by three independent surveys of cassava mosaic virus disease in Rwanda and Burundi

Cassava mosaic disease (CMD) seriously affects cassava yields in Africa. This study compared the spatial distribution of CMD using three independent surveys in Rwanda and Burundi. Geostatistical techniques were used to interpolate the point-based surveys and predict the spatial distributions of different measures of the disease. Correlative relationships were examined for 35 environmental and socio-economic spatial variables of which 31 were correlated to CMD intensity, with the highest correlation coefficients for latitude (-0·47), altitude (-0·36) and temperature (+0·36). The most significant explanatory variables were entered in separate linear regression models for each of the surveys. The models explained 54%, 44% and 22% of the variation in CMD. The residuals of the regression models were interpolated using kriging and added to the regression models to map CMD across both countries. Significant differences were calculated in some areas after correcting for interpolation error. An important explanation of the differences is interaction between the CMD pandemic and the dates of the three surveys. Large relative prediction errors obtained in the regression kriging procedure show the need to improve the survey design and decrease measurement error. Improved maps of crop diseases such as CMD could aid targeting of control interventions and thereby contribute to increasing crop yields. This study validated the unique character of each of the survey approaches adopted and underlines the importance of specific interpretation of results for CMD management. The study emphasizes the need for optimization of sampling designs and survey protocols to maximize the potential of regression krigin

Comparison of disease patterns assessed by three independent surveys of cassava mosaic virus disease in Rwanda and Burundi

Cassava mosaic disease (CMD) seriously affects cassava yields in Africa. This study compared the spatial distribution of CMD using three independent surveys in Rwanda and Burundi. Geostatistical techniques were used to interpolate the pointbased surveys and predict the spatial distributions of different measures of the disease. Correlative relationships were examined for 35 environmental and socio-economic spatial variables of which 31 were correlated to CMD intensity, with the highest correlation coefficients for latitude ()0Æ47), altitude ()0Æ36) and temperature (+0Æ36). The most significant explanatory variables were entered in separate linear regression models for each of the surveys. The models explained 54%, 44% and 22% of the variation in CMD. The residuals of the regression models were interpolated using kriging and added to the regression models to map CMD across both countries. Significant differences were calculated in some areas after correcting for interpolation error. An important explanation of the differences is interaction between the CMD pandemic and the dates of the three surveys. Large relative prediction errors obtained in the regression kriging procedure show the need to improve the survey design and decrease measurement error. Improved maps of crop diseases such as CMD could aid targeting of control interventions and thereby contribute to increasing crop yields. This study validated the unique character of each of the survey approaches adopted and underlines the importance of specific interpretation of results for CMD management. The study emphasizes the need for optimization of sampling designs and survey protocols to maximize the potential of regression kriging

Regional fluid flow and gold mineralization in the Dalradian of the Sperrin Mountains, northern Ireland

Gold vein mineralization occurs in the metamorphosed and deformed Dalradian (Neoproterozoic) rocks of the Sperrin Mountains, Northern Ireland. Two structures exerted a control on the location of the mineralization; the north-south Omagh lineament and the west-northwest-east-southeast Curraghinalt lateral ramp in the footwall of the northeast-southwest Omagh thrust. These are Caledonian structures resulting from the thrusting of Dalradian rocks over a possibly still active Ordovician arc. Cathodoluminescence microscopy distinguishes four phases of vein quartz in the Curraghinalt gold prospect. Fluid inclusion studies and stable isotope geochemistry have defined the probable fluids responsible for the precipitation of each quartz phase and associated sulfide and precious metal mineralization. The initial phase (QI) appears to have been associated with the main Caledonian metamorphic event (ca. 470 Ma) and is nonauriferous. The second phase (Q2) forms an extensive cement to brecciated early quartz and is believed to have involved a fluid (similar to 15 wt % CO2 10 wt % NaCl + KCl equiv) with a significant magmatic component of 470 to 400 Ma, which underwent phase separation and dilution with a cooler formation water. This process resulted in precipitation of the main phase of gold mineralization characterized by an assemblage of electrum, pyrite, arsenopyrite, chalcopyrite, tennantite-tetrahedrite, and Various tellurides. Similar fluids are observed on a regional scale, concentrated within the hanging wall of the Omagh thrust, indicating an extensive fluid-flow event. The relative abundance of gold at the Curraghinalt and Cavanacaw prospects is thought to be due to higher fluid fluxes in favorable zones of dilation and closer proximity to the fluid source. The deposit was subsequently reactivated with the precipitation of later quartz (Q3-Q4) from a formation water believed to be resident in the Dalradian metasediments, which mixed with a low-temperature, high- salinity basinal brine, probably during Carboniferous basin inversion. Brine flow resulted in the remobilization of earlier electrum, reducing its fineness, and also introduced base metal sulfides, carbonates, and barite. Again, brine flow is localized by the Omagh thrust, indicating the long-lived role of this structure in controlling regional fluid migration

5G-XHaul: A Novel Wireless-Optical SDN Transport Network to Support Joint 5G Backhaul and Fronthaul Services

The increased carrier bandwidth and the number of antenna elements expected in 5G networks require a redesign of the traditional IP-based backhaul and CPRI-based fronthaul interfaces used in 4G networks. We envision future mobile networks to encompass these legacy interfaces together with novel 5G RAN functional splits. In this scenario, a consistent transport network architecture able to jointly support backhaul and 4G/5G fronthaul interfaces is of paramount importance. In this article we present 5G-XHaul, a novel transport network architecture featuring wireless and optical technologies and a multi-technology software defined control plane, which is able to jointly support backhaul and fronthaul services. We have deployed and validated the 5G-XHaul architecture in a city-wide testbed in Bristol. © 2019 IEEE

5G-XHaul: A Novel Wireless-Optical SDN Transport Network to Support Joint 5G Backhaul and Fronthaul Services

The increased carrier bandwidth and the number of antenna elements expected in 5G networks require a redesign of the traditional IP-based backhaul and CPRI-based fronthaul interfaces used in 4G networks. We envision future mobile networks to encompass these legacy interfaces together with novel 5G RAN functional splits. In this scenario, a consistent transport network architecture able to jointly support backhaul and 4G/5G fronthaul interfaces is of paramount importance. In this article we present 5G-XHaul, a novel transport network architecture featuring wireless and optical technologies and a multi-technology software defined control plane, which is able to jointly support backhaul and fronthaul services. We have deployed and validated the 5G-XHaul architecture in a city-wide testbed in Bristol. © 2019 IEEE