5,129 research outputs found

    The genetics of resistance to grapevine fanleaf virus in Vitis vinifera

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    Two wild Vitis vinifera accessions from the Middle East previously found to be resistant to grapevine fanleaf virus (GFV) were selfed and also crossed to a GFV-susceptible female cultivar. Five seedling populations of 60 plants each were established. A micrografting procedure was developed for screening the seedlings whereby single-node seedling stem segments were cleft-grafted go GFV-infected stocks in vitro. After 8 weeks, scion tissue was scored phenotypically and assayed by ELISA to measure virus titer. Resistance to GFV appears to segregate as a recessive trait controlled by at least two genes

    Acoustic characterization of crack damage evolution in sandstone deformed under conventional and true triaxial loading

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    We thank the Associate Editor, Michelle Cooke, and the reviewers, Ze'ev Reches and Yves GuĂ©guen, for useful comments which helped to improve the manuscript. We thank J.G. Van Munster for providing access to the true triaxial apparatus at KSEPL and for technical support during the experimental program. We thank R. Pricci for assistance with technical drawings of the apparatus. This work was partly funded by NERC award NE/N002938/1 and by a NERC Doctoral Studentship, which we gratefully acknowledge. Supporting data are included in a supporting information file; any additional data may be obtained from J.B. (e-mail: [email protected]).Peer reviewedPublisher PD

    Sources of resistance to grapevine fanleaf virus (GFV) in Vitis species

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    A diverse array of Vitis germplasm was screened to identify sources of resistance to grapevine fanleaf virus (GFV). The 173 accessions screened included Vitis species, cultivars, and interspecific hybrids. Since Vitis vinifera and GFV are thought to have a common origin in the Middle East, particular attention was paid to this species - 27 Middle Eastern vinifera accessions and 9 vinifera cultivars were surveyed. In addition, North American accessions of 24 Euvitis species and 2 Muscadinia species were tested, including cultivars of rotundifolia, as were accessions of 5 Asian species. The interspecific hybrids included 3 vinifera x rotundifolia (VR) hybrids known to be resistant to the feeding of Xiphinema index, the nematode vector of GFV. The vines to be tested were approach grafted to infected Cabernet Sauvignon vines and subsequently screened for the presence of the virus by ELISA. 3 GFV-resistant accessions were identified - a Middle Eastern vinifera, rotundifolia cv. Bountiful, and one of the VR hybrids. Several vinifera accessions (including some cultivars) previously reported to be GFV-resistant were susceptible in this study. These results suggest that two forms of GFV resistance, hast plant resistance and nonhost resistance, exist in Vitis germplasm

    Genetic transformation of Vitis vinifera L. cvs Thompson Seedless and Chardonnay with the pear PGIP and GFP encoding genes

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    Transgenic plants of Vitis vinifera L. cvs. Chardonnay and Thompson Seedless expressing the ÎČ-glucuronidase gene (GUS) and either the pear polygalacturonase inhibiting protein gene (PGIP) or the green fluorescent protein gene (GFP) were produced via somatic embryogenesis. Various media and culture conditions were tested in order to develop an efficient transformation method. Best results were obtained when embryogenic callus was initiated from anthers cultured on PIV medium and maintained in PT medium. Embryogenic lines of the rootstocks Saint George, 110 Richter and Freedom and from inflorescence primordia of Chardonnay and 110 Richter were also established using the same media. Inoculation with 109 cells·ml-1 Agrobacterium resulted in a higher number of selected calli than cultures inoculated with 107 or 108 cells·ml-1. Plants were regenerated in a modified WP medium from up to 46 % of the selected callus. Approximately 80 % of the lines expressed GUS and either PGIP or GFP but a low correlation was found between ÎČ-glucuronidase and polygalacturonase inhibiting protein activities.

    Identity and parentage of two alpine grape cultivars from Switzerland (Vitis vinifera L. Lafnetscha and Himbertscha)

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    Four closely related white grape cultivars from the Western Alps (Switzerland) - Humagne Blanc, Completer, Lafnetscha and Himbertscha - and three putative relatives or synonyms - Gouais Blanc, Plantscher and Bordeaux Blanc - were analyzed with up to 50 microsatellite markers. Humagne Blanc and Completer are ancient cultivars from the Haut-Valais and GraubĂŒnden regions, respectively. Lafnetscha and Himbertscha are lesser-known cultivars scarcely cultivated in Haut-Valais. Lafnetscha is frequently considered as synonym of Completer. Himbertscha might be related to Gouais Blanc, one of the parents of Chardonnay, Gamay, etc. Plantscher, a putative synonym of Lafnetscha, is scarcely cultivated in Haut-Valais (Switzerland) and Bordeaux Blanc (or Gros Bourgogne) is a cultivar of unknown origin (despite its names) cultivated in Switzerland. Our results allowed us to determine the true-to-type Lafnetscha and confirmed that Lafnetscha is not a synonym of Completer. Plantscher is not a synonym of Lafnetscha but a synonym of Bordeaux Blanc (or Gros Bourgogne) and is a likely parent or progeny of the Hungarian Furmint. Himbertscha is not related to Gouais Blanc and shares at least one allele at each locus with Humagne Blanc, providing strong evidence of a parent/progeny relationship. Given that Humagne Blanc is an older cultivar, we propose that it is the parent of Himbertscha. Alleles at 49 out of 50 microsatellite loci are consistent with Lafnetscha being the progeny of Completer and Humagne Blanc. The exception is a 10-base pair discrepancy at one locus (VVMD 36), most likely due to the occurrence of a null allele, since this parentage is supported at other markers by very high likelihood ratios. With Lafnetscha = Completer x Humagne Blanc, we present the second grape cultivar parentage showing a multiple repeat discrepancy at one locus. This study emphasizes that one multiple repeat unit discrepancy is not sufficient to reject a parentage, and that the greater is the number of loci, the greater are the chances to encounter null alleles or clonal mutations

    Reducing the number and impact of outbreaks of nosocomial viral gastroenteritis: Time-series analysis of a multidimensional quality improvement initiative

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    Background Nosocomial norovirus infections and their control measures disrupt patient care, increase staff workload and raise healthcare costs. Objective To determine the impact on outbreaks of nosocomial viral gastroenteritis, staff and patients affected, and bed closures of a multidimensional quality improvement (QI) initiative focused on education; improved patient surveillance; early automated recognition and notification of infection of index patients; and proactive care and control measures. Methods In a pragmatic, retrospective, observational study, we compared numbers of suspected/confirmed norovirus outbreaks at Portsmouth Hospitals National Health Service Trust (PHT) with regional and national data, before and after a multidimensional QI initiative. We also compared mean daily bed closures due to norovirus-like symptoms. At PHT only we recorded patient and staff numbers with norovirus-like symptoms, and days of disruption due to outbreaks. Results Annual outbreak numbers fell between 2009-2010 and 2010-2014 by 91% at PHT compared with 15% and 28% for Wessex and England, respectively. After April 2010, recorded outbreaks were 8 (PHT), 383 (Wessex) and 5063 (England). For the winter periods from 2010/ 2011 to 2013/2014, total bed closures due to norovirus were 38 (PHT; mean 0.5 per week), 3565 (Wessex hospitals; mean 48.8 per hospital per week) and 2730 (England; mean 37.4 per hospital per week). At PHT, patients affected by norovirus-like symptoms fell by 92%, affected staff by 81% and days of disruption by 88%. Conclusions A multiyear QI programme, including use of real-time electronic identification of patients with norovirus-like symptoms, and an early robust response to suspected infection, resulted in virtual elimination of outbreaks. The ability to identify index cases of infection early facilitates prompt action to prevent ongoing transmission and appears to be a crucial intervention

    Use of strategies to improve retention in primary care randomised trials: a qualitative study with in-depth interviews

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    Objective To explore the strategies used to improve retention in primary care randomised trials.<p></p> Design Qualitative in-depth interviews and thematic analysis.<p></p> Participants 29 UK primary care chief and principal investigators, trial managers and research nurses.<p></p> Methods In-depth face-to-face interviews.<p></p> Results Primary care researchers use incentive and communication strategies to improve retention in trials, but were unsure of their effect. Small monetary incentives were used to increase response to postal questionnaires. Non-monetary incentives were used although there was scepticism about the impact of these on retention. Nurses routinely used telephone communication to encourage participants to return for trial follow-up. Trial managers used first class post, shorter questionnaires and improved questionnaire designs with the aim of improving questionnaire response. Interviewees thought an open trial design could lead to biased results and were negative about using behavioural strategies to improve retention. There was consensus among the interviewees that effective communication and rapport with participants, participant altruism, respect for participant's time, flexibility of trial personnel and appointment schedules and trial information improve retention. Interviewees noted particular challenges with retention in mental health trials and those involving teenagers.<p></p> Conclusions The findings of this qualitative study have allowed us to reflect on research practice around retention and highlight a gap between such practice and current evidence. Interviewees describe acting from experience without evidence from the literature, which supports the use of small monetary incentives to improve the questionnaire response. No such evidence exists for non-monetary incentives or first class post, use of which may need reconsideration. An exploration of barriers and facilitators to retention in other research contexts may be justified.<p></p&gt

    Relating seismic velocities, thermal cracking and permeability in Mt. Etna and Iceland basalts

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    We report simultaneous laboratory measurements of seismic velocities and fluid permeability on lava flow basalt from Etna (Italy) and columnar basalt from Seljadur (Iceland). Measurements were made in a servo-controlled steady-state-flow permeameter at effective pressures from 5–80 MPa, during both increasing and decreasing pressure cycles. Selected samples were thermally stressed at temperatures up to 900 °C to induce thermal crack damage. Acoustic emission output was recorded throughout each thermal stressing experiment. At low pressure (0–10 MPa), the P-wave velocity of the columnar Seljadur basalt was 5.4 km/s, while for the Etnean lava flow basalt it was only 3.0–3.5 km/s. On increasing the pressure to 80 MPa, the velocity of Etnean basalt increased by 45%–60%, whereas that of Seljadur basalt increased by less than 2%. Furthermore, the velocity of Seljadur basalt thermally stressed to 900 °C fell by about 2.0 km/s, whereas the decrease for Etnean basalt was negligible. A similar pattern was observed in the permeability data. Permeability of Etnean basalt fell from about 7.5×10−16 m2 to about 1.5×10−16 m2 over the pressure range 5–80 MPa, while that for Seljadur basalt varied little from its initial low value of 9×10−21 m2. Again, thermal stressing significantly increased the permeability of Seljadur basalt, whilst having a negligible effect on the Etnean basalt. These results clearly indicate that the Etnean basalt contains a much higher level of crack damage than the Seljadur basalt, and hence can explain the low velocities (3–4 km/s) generally inferred from seismic tomography for the Mt. Etna volcanic edifice

    Development of Upset Recovery and Basic Aerobatic Courses for Collegiate Flight Training Programs

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    Upset recovery and aerobatics are two topics in general aviation that are often overlooked by commercial pilots in training. This can be due to several different constraints, such as not having the time or resources to receive optional flight instruction, or the workload involved with locating a reputable school and qualified flight instructor. In addition, upset recovery and aerobatics training is not required to become a commercially rated pilot and start a career in the aviation industry. However, both topics, especially upset recovery, can increase a pilot’s awareness of the limitations of their own aircraft and increase their confidence when faced with a loss–of-control situation. Implementing upset recovery and aerobatics into a collegiate flight training curriculum would mitigate some of the constraints that a pilot faces when making the decision to pursue this training. This paper begins by analyzing the limited upset recovery training that a student pilot receives during their primary flight training and how this relates to the frequency and types of aircraft accidents caused by a loss of control. Next, a sample collegiate flight training curriculum will be reviewed to identify subject areas that are expanded upon in upset recovery and aerobatic training. The presentation will discuss how areas identified in this curriculum could be used to develop abbreviated syllabi for collegiate upset recovery and aerobatic courses that could be grounded in academics and serve as an advantageous addition to the primary training a college student receives in their collegiate flight training program
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