The inheritance of resistance to bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians in three lettuce cultivars.

Lettuce yields can be reduced by the disease bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) and host resistance is the most feasible method to reduce disease losses. The cultivars La Brillante, Pavane and Little Gem express an incompatible host-pathogen interaction as a hypersensitive response (HR) to California strains of Xcv resulting in resistance. Little was known about the inheritance of resistance; however, resistance to other lettuce pathogens is often determined by resistance gene candidates (RGCs) encoding nucleotide-binding leucine-rich repeat (NB-LRR) proteins. Therefore, we determined the inheritance of BLS resistance in the cultivars La Brillante, Little Gem and Pavane and mapped it relative to RGCs. The reaction to Xcv was analyzed in nine F1, F2 and recombinant inbred line populations of lettuce from HR×compatible or HR×HR crosses. The HR in La Brillante, Pavane and Little Gem is conditioned by single dominant genes, which are either allelic or closely linked genes. The resistance gene in La Brillante was designated Xanthomonas resistance 1 (Xar1) and mapped to lettuce linkage group 2. Xar1 is present in a genomic region that contains numerous NB-LRR encoding RGCs and functional pathogen resistance loci in the RGC2 family. The Xar1 gene confers a high level of BLS resistance in the greenhouse and field that can be introgressed into commercial lettuce cultivars to reduce BLS losses using molecular markers

Expert Programmer versus Parallelizing Compiler: A Comparative Study of Two Approaches for Distributed Shared Memory

This article critically examines current parallel programming practice and optimizing compiler development. The general strategies employed by compiler and programmer to optimize a Fortran program are described, and then illustrated for a specific case by applying them to a well-known scientific program, TRED2, using the KSR-1 as the target architecture. Extensive measurement is applied to the resulting versions of the program, which are compared with a version produced by a commercial optimizing compiler, KAP. The compiler strategy significantly outperforms KAP and does not fall far short of the performance achieved by the programmer. Following the experimental section each approach is critiqued by the other. Perceived flaws, advantages, and common ground are outlined, with an eye to improving both schemes

Evaluating worksharing tasks on distributed environments

©2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Hybrid programming is a promising approach to exploit clusters of multicore systems. Our focus is on the combination of MPI and tasking. This hybrid approach combines the low-latency and high throughput of MPI with the flexibility of tasking models and their inherent ability to handle load imbalance. However, combining tasking with standard MPI implementations can be a challenge. The Task-Aware MPI library (TAMPI) eases the development of applications combining tasking with MPI. TAMPI enables developers to overlap computation and communication phases by relying on the tasking data-flow execution model. Using this approach, the original computation that was distributed in many different MPI ranks is grouped together in fewer MPI ranks, and split into several tasks per rank. Nevertheless, programmers must be careful with task granularity. Too fine-grained tasks introduce too much overhead, while too coarse-grained tasks lead to lack of parallelism. An adequate granularity may not always exist, especially in distributed environments where the same amount of work is distributed among many more cores. Worksharing tasks are a special kind of tasks, recently proposed, that internally leverage worksharing techniques. By doing so, a single worksharing task may run in several cores concurrently. Nonetheless, the task management costs remain the same than a regular task. In this work, we study the combination of worksharing tasks and TAMPI on distributed environments using two well known mini-apps: HPCCG and LULESH. Our results show significant improvements using worksharing tasks compared to regular tasks, and to other state-of-the-art alternatives such as OpenMP worksharing.This project is supported by the European Union’s Horizon 2020 Research and Innovation programme under grant agreement No.s 754304 (DEEP-EST) and 823767 (PRACE), the Ministry of Economy of Spain through the Severo Ochoa Center of Excellence Program (SEV-2015-0493), by the Spanish Ministry of Science and Innovation (contract PID2019-107255GB) and by the Generalitat de Catalunya (2017-SGR1481). The work has been performed under the Project HPCEUROPA3 (INFRAIA-2016-1-730897), with the support of the EC Research Innovation Action under the H2020 Programme; in particular, the author gratefully acknowledges the support of Dr Mark Bull (EPCC) and the computer resources and technical support provided by EPCC.Peer ReviewedPostprint (author's final draft

Nonadiabatic Dynamics between Valence, Nonvalence, and Continuum Electronic States in a Heteropolycyclic Aromatic Hydrocarbon

Internal conversion between valence-localized and dipole-bound states is thought to be a ubiquitous process in polar molecular anions, yet there is limited direct evidence. Here, photodetachment action spectroscopy and time-resolved photoelectron imaging with a heteropolycyclic aromatic hydrocarbon (hetero-PAH) anion, deprotonated 1-pyrenol, is used to demonstrate a subpicosecond (τ1 = 160 ± 20 fs) valence to dipole-bound state internal conversion following excitation of the origin transition of the first valence-localized excited state. The internal conversion dynamics are evident in the photoelectron spectra and in the photoelectron angular distributions (β2 values) as the electronic character of the excited state population changes from valence to nonvalence. The dipole-bound state subsequently decays through mode-specific vibrational autodetachment with a lifetime τ2 = 11 ± 2 ps. These internal conversion and autodetachment dynamics are likely common in molecular anions but difficult to fingerprint due to the transient existence of the dipole-bound state. Potential implications of the present excited state dynamics for interstellar hetero-PAH anion formation are discussed

Photodetachment and photoreactions of substituted naphthalene anions in a tandem ion mobility spectrometer

Substituted naphthalene anions (deprotonated 2-naphthol and 6-hydroxy-2-naphthoic acid) are spectroscopically probed in a tandem drift tube ion mobility spectrometer (IMS). Target anions are selected according to their drift speed through nitrogen buffer gas in the first IMS stage before being exposed to a pulse of tunable light that induces either photodissociation or electron photodetachment, which is conveniently monitored by scavenging the detached electrons with trace SF6 in the buffer gas. The photodetachment action spectrum of the 2-naphtholate anion exhibits a band system spanning 380-460 nm with a prominent series of peaks spaced by 440 cm-1, commencing at 458.5 nm, and a set of weaker peaks near the electron detachment threshold corresponding to transitions to dipole-bound states. The two deprotomers of 6-hydroxy-2-naphthoic acid are separated and spectroscopically probed independently. The molecular anion formed from deprotonation of the hydroxy group gives rise to a photodetachment action spectrum similar to that of the 2-naphtholate anion with an onset at 470 nm and a maximum at 420 nm. Near the threshold, the photoreaction with SF6 is observed with displacement of an OH group by an F atom. In contrast, the anion formed from deprotonation of the carboxylic acid group gives rise to a photodissociation action spectrum, recorded on the CO2 loss channel, lying at much shorter wavelengths with an onset at 360 nm and maximum photoresponse at 325 nm

How important is the land use mix measure in understanding walking behaviour? Results from the RESIDE study

<p>Abstract</p> <p>Background</p> <p>Understanding the relationship between urban design and physical activity is a high priority. Different representations of land use diversity may impact the association between neighbourhood design and specific walking behaviours. This study examined different entropy based computations of land use mix (LUM) used in the development of walkability indices (WIs) and their association with walking behaviour.</p> <p>Methods</p> <p>Participants in the RESIDential Environments project (RESIDE) self-reported mins/week of recreational, transport and total walking using the Neighbourhood Physical Activity Questionnaire (n = 1798). Land use categories were incrementally added to test five different LUM models to identify the strongest associations with recreational, transport and total walking. Logistic regression was used to analyse associations between WIs and walking behaviour using three cut points: any (> 0 mins), ≥ 60 mins and ≥ 150 mins walking/week.</p> <p>Results</p> <p>Participants in high (vs. low) walkable neighbourhoods reported up to almost twice the amount of walking, irrespective of the LUM measure used. However, different computations of LUM were found to be relevant for different types and amounts of walking (i.e., > 0, ≥ 60 or ≥ 150 mins/week). Transport walking (≥ 60 mins/week) had the strongest and most significant association (OR = 2.24; 95% CI:1.58-3.18) with the WI when the LUM included 'residential', 'retail', 'office', 'health, welfare and community', <it>and </it>'entertainment, culture and recreation'. However, any (> 0 mins/week) recreational walking was more strongly associated with the WI (OR = 1.36; 95% CI:1.04-1.78) when land use categories included 'public open space', 'sporting infrastructure' and 'primary and rural' land uses. The observed associations were generally stronger for ≥ 60 mins/week compared with > 0 mins/week of transport walking and total walking but this relationship was not seen for recreational walking.</p> <p>Conclusions</p> <p>Varying the combination of land uses in the LUM calculation of WIs affects the strength of relationships with different types (and amounts) of walking. Future research should examine the relationship between walkability and specific types and different amounts of walking. Our results provide an important first step towards developing a context-specific WI that is associated with recreational walking. Inherent problems with administrative data and the use of entropy formulas for the calculation of LUM highlight the need to explore alternative or complimentary measures of the environment.</p

Barley yield formation under abiotic stress depends on the interplay between flowering time genes and environmental cues

Abstract Since the dawn of agriculture, crop yield has always been impaired through abiotic stresses. In a field trial across five locations worldwide, we tested three abiotic stresses, nitrogen deficiency, drought and salinity, using HEB-YIELD, a selected subset of the wild barley nested association mapping population HEB-25. We show that barley flowering time genes Ppd-H1, Sdw1, Vrn-H1 and Vrn-H3 exert pleiotropic effects on plant development and grain yield. Under field conditions, these effects are strongly influenced by environmental cues like day length and temperature. For example, in Al-Karak, Jordan, the day length-sensitive wild barley allele of Ppd-H1 was associated with an increase of grain yield by up to 30% compared to the insensitive elite barley allele. The observed yield increase is accompanied by pleiotropic effects of Ppd-H1 resulting in shorter life cycle, extended grain filling period and increased grain size. Our study indicates that the adequate timing of plant development is crucial to maximize yield formation under harsh environmental conditions. We provide evidence that wild barley alleles, introgressed into elite barley cultivars, can be utilized to support grain yield formation. The presented knowledge may be transferred to related crop species like wheat and rice securing the rising global food demand for cereals

Pockmarks in the Witch Ground Basin, central north sea

Marine sediments host large amounts of methane (CH4), which is a potent greenhouse gas. Quantitative estimates for methane release from marine sediments are scarce, and a poorly constrained temporal variability leads to large uncertainties in methane emission scenarios. Here, we use 2‐D and 3‐D seismic reflection, multibeam bathymetric, geochemical, and sedimentological data to (I) map and describe pockmarks in the Witch Ground Basin (central North Sea), (II) characterize associated sedimentological and fluid migration structures, and (III) analyze the related methane release. More than 1,500 pockmarks of two distinct morphological classes spread over an area of 225 km2. The two classes form independently from another and are corresponding to at least two different sources of fluids. Class 1 pockmarks are large in size (>6 m deep, >250 m long, and >75 m wide), show active venting, and are located above vertical fluid conduits that hydraulically connect the seafloor with deep methane sources. Class 2 pockmarks, which comprise 99.5% of all pockmarks, are smaller (0.9–3.1 m deep, 26–140 m long, and 14–57 m wide) and are limited to the soft, fine‐grained sediments of the Witch Ground Formation and possibly sourced by compaction‐related dewatering. Buried pockmarks within the Witch Ground Formation document distinct phases of pockmark formation, likely triggered by external forces related to environmental changes after deglaciation. Thus, greenhouse gas emissions from pockmark fields cannot be based on pockmark numbers and present‐day fluxes but require an analysis of the pockmark forming processes through geological time

Fault interactions and reactivation within a normal-fault network at Milne Point, Alaska

A normal-fault network from Milne Point, Alaska, is investigated focusing on characterizing geometry, displacement, strain, and different fault interactions. The network, constrained from three-dimensional seismic reflection data, comprises two generations of faults: Cenozoic north-northeast–trending faults and Jurassic west-northwest–trending faults, which highly compartmentalize Upper Triassic to Lower Cretaceous reservoirs. The west-northwest–trending faults are influenced by a similarly oriented underlying structural grain. This influence is characterized by increases in throw on several faults, strain localization, reorientation of faults and an increase in linkage maturity.Reconstructing fault plane geometries and mapping spatial variations in throw identified key characteristic features in their interactions and reactivation of pre-existing structures. Faults are divided into isolated, abutting, and splaying faults. Isolated faults exhibit a range of displacement profiles depending on the degree of restriction at fault tips. Fault splays accommodate step-like decreases in throw along larger main faults with a throw maximum at the intersection with the main fault. Throw profiles of abutting faults are divided into two groups: early stage abutting faults with throw minima at both the isolated and abutting tips, and developed abutting faults with throw maxima near the abutting tip.Developed abutting faults accumulate throw after initial abutment, locally reactivating and transferring throw onto the pre-existing fault. Two abutting faults can link kinematically by reactivating a segment of the pre-existing fault forming a trailing fault. The motion sense of the trailing fault can be synthetic or antithetic to the reactivated pre-existing fault, producing increases or decreases in the throw of the pre-existing fault, respectivel