894 research outputs found

    Effects of thermotherapy and virus status on yield, annual growth and grape composition of Sultana

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    A high yielding Sultana clone, H5, infected with yellow speckle and leafroll diseases was compared over 5 harvests with 6 heat-treated H5 clones, 3 of which still contained both diseases and 3 from which leafroll had been eliminated, and also with a Thompson Seedless clone (FV B6Vl HT91) from California. There were no differences between .the untreated H5 clone and the Thompson Seedless clone which was infected with only yeilow speckle for any of the measured variables in any season.The mean yield of heat-treated H5 clones was reduced by 6 % in those which still contained both diseases and was not affected in those from which leafroll had been eliminated. The yield reduction was related to fewer inflorescences.The mean weight of annual shoot growth, berry weight, calculated bunch. weight, sugar concentration and pH and titratable acidity of juice, did not differ between the 4 groups.Long periods of heat treatment (196-938 d) produced no clones with yields or annual shoot growth superior to the untreated source clone.Except for expression of leaf symptoms associated with leafroll, all 6 heat-treated H5 clones showed no obvious morphological differences from their original source clone, nor did the heat-treated Thompson Seedless clone.Der Einßuß von Thermotherapie und Virusbefall auf Traubenertrag, Holzproduktion und Traubenqualität der Rebsorte SultanaZusammenfassung. - Der an Yellow speckle und Leafroll erkrankte ertragsstarke Sultana-Klon H5 wurde 5 Ernteperioden lang mit 6 wärmebehandelten H5-Klonen - 3 davon noch mit beiden Krankheiten, 3 nur noch mit Yellow speckle behaftet - sowie mit einem Thompson-Seedless-Klon (FV B6Vl HT91) aus Kalifornien verglichen.Zwischen dem unbehandelten H5-Klon und dem Thompson-Seedless-Klon, der nur an Yellow speckle erkrankt war, wurden in keinem Jahr irgendwelche Unterschiede der erfaßten Meßgrößen festgestellt.Der mittlere Traubenertrag der wärmebehandelten H5-Klone war bei den doppelt erkrankten Reben um 6 % verringert und bei den Leafroll-freien Reben nicht beeinflußt. Der Ertragsrückgang war mit einer geringeren Anzahl von Infloreszenzen verbunden.Die 4 Versuchsgruppen zeigten keine Unterschiede bei jährlichem Holzzuwachs, Beerengewicht und kalkuliertem Traubengewicht sowie Zuckerkonzentration, pH und titrierbarer Säure des Beerensaftes.Lange Perioden der Wärmebehandlung (196-338 d) ergaben keine Klone, die in ihrem Traubenertrag oder der Holzproduktion dem unbehandelten Ausgangsklon überlegen gewesen wären.Abgesehen von den Leafroll-Symptomen der Blätter zeigten alle 6 wärmebehandelten H5-Klone keine erkennbaren morphologischen Abweichungen von ihrem Ausgangsklon; Entsprechendes gilt für den wärmebehandelten Thompson-Seedless-Klon

    Prevalence of Advanced, Precancerous Colorectal Neoplasms in Black and White Populations: A Systematic Review and Meta-analysis

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    Background & Aims Colorectal cancer (CRC) incidence and mortality are higher in black vs white populations. The reasons for these disparities are not clear, yet some guidelines recommend screening black persons for CRC starting at ages 40–45 years. We performed a systematic review and meta-analysis to compare the prevalence of advanced adenomas (AAs) and advanced, precancerous colorectal neoplasms (ACNs) between asymptomatic black and white screen-eligible adults. Methods We searched Ovid MEDLINE, PubMed, Embase, and the Cochrane Library to identify articles (published from 1946 through June 2017) that reported prevalence values of AA or ACN in average-risk black and white individuals undergoing screening colonoscopy. Two authors independently assessed study quality and risk for bias using a modified validated quality assessment instrument. Following the PRISMA guidelines, 2 authors independently abstracted descriptive and quantitative data from each study. We performed a random effects meta-analysis to determine risk differences and odds ratios (ORs). Results From 1653 articles, we identified 9 studies for analysis, comprising 302,128 individuals. Six of the 9 studies were of high methodological quality, had a low risk for bias, and were included in the meta-analysis. In these 9 studies, the overall prevalence values for AA and ACN did not differ significantly between back (6.57%) and white screened individuals (6.20%; OR, 1.03; 95% CI, 0.81–1.30). Among a subgroup of 5 studies, the prevalence of proximal AA and ACN was significantly higher in black (3.30%) than in white screened individuals (2.42%; OR, 1.20; 95% CI, 1.12–1.30). Excluding the largest study did not affect overall prevalence (OR, 0.99; CI, 0.73–1.34) but eliminated the difference in prevalence of proximal AA or ACN (OR, 1.48; 95% CI, 0.87–2.52). Conclusions In a meta-analysis, we found the overall prevalence of AA and ACN did not differ significantly between average-risk black and white persons, indicating that the age at which to begin CRC screening need not differ based on race

    Global assessment of nitrogen deposition effects on terrestrial plant diversity : a synthesis

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    Atmospheric nitrogen (N) deposition is it recognized threat to plant diversity ill temperate and northern parts of Europe and North America. This paper assesses evidence from field experiments for N deposition effects and thresholds for terrestrial plant diversity protection across a latitudinal range of main categories of ecosystems. from arctic and boreal systems to tropical forests. Current thinking on the mechanisms of N deposition effects on plant diversity, the global distribution of G200 ecoregions, and current and future (2030) estimates of atmospheric N-deposition rates are then used to identify the risks to plant diversity in all major ecosystem types now and in the future. This synthesis paper clearly shows that N accumulation is the main driver of changes to species composition across the whole range of different ecosystem types by driving the competitive interactions that lead to composition change and/or making conditions unfavorable for some species. Other effects such its direct toxicity of nitrogen gases and aerosols long-term negative effects of increased ammonium and ammonia availability, soil-mediated effects of acidification, and secondary stress and disturbance are more ecosystem, and site-specific and often play a supporting role. N deposition effects in mediterranean ecosystems have now been identified, leading to a first estimate of an effect threshold. Importantly, ecosystems thought of as not N limited, such as tropical and subtropical systems, may be more vulnerable in the regeneration phase. in situations where heterogeneity in N availability is reduced by atmospheric N deposition, on sandy soils, or in montane areas. Critical loads are effect thresholds for N deposition. and the critical load concept has helped European governments make progress toward reducing N loads on sensitive ecosystems. More needs to be done in Europe and North America. especially for the more sensitive ecosystem types. including several ecosystems of high conservation importance. The results of this assessment Show that the Vulnerable regions outside Europe and North America which have not received enough attention are ecoregions in eastern and Southern Asia (China, India), an important part of the mediterranean ecoregion (California, southern Europe). and in the coming decades several subtropical and tropical parts of Latin America and Africa. Reductions in plant diversity by increased atmospheric N deposition may be more widespread than first thought, and more targeted Studies are required in low background areas, especially in the G200 ecoregions

    Variants within TSC2 exons 25 and 31 are very unlikely to cause clinically diagnosable tuberous sclerosis

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    Inactivating mutations in TSC1 and TSC2 cause tuberous sclerosis complex (TSC). The 2012 international consensus meeting on TSC diagnosis and management agreed that the identification of a pathogenic TSC1 or TSC2 variant establishes a diagnosis of TSC, even in the absence of clinical signs. However, exons 25 and 31 of TSC2 are subject to alternative splicing. No variants causing clinically diagnosed TSC have been reported in these exons raising the possibility that such variants would not cause TSC. We present truncating and in-frame variants in exons 25 and 31 in three individuals unlikely to fulfil TSC diagnostic criteria and examine the importance of these exons in TSC using different approaches. Amino acid conservation analysis suggests significantly less conservation in these exons compared to the majority of TSC2 exons, and TSC2 expression data demonstrates that the majority of TSC2 transcripts lack exons 25 and/or 31 in many human adult tissues. In vitro assay of both exons shows that neither exon is essential for TSC complex function. Our evidence suggests that variants in TSC2 exons 25 or 31 are very unlikely to cause classical TSC, although a role for these exons in tissue/stage specific development cannot be excluded

    Matched Filter Stochastic Background Characterization for Hyperspectral Target Detection

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    Algorithms exploiting hyperspectral imagery for target detection have continually evolved to provide improved detection results. Adaptive matched filters can be used to locate spectral targets by modeling scene background as either structured (geometric) with a set of endmembers (basis vectors) or as unstructured (stochastic) with a covariance or correlation matrix. These matrices are often calculated using all available pixels in a data set. In unstructured background research, various techniques for improving upon scene-wide methods have been developed, each involving either the removal of target signatures from the background model or the segmentation of image data into spatial or spectral subsets. Each of these methods increase the detection signal-to-background ratio (SBR) and the multivariate normality (MVN) of the data from which background statistics are calculated, thus increasing separation between target and non-target species in the detection statistic and ultimately improving thresholded target detection results. Such techniques for improved background characterization are widely practiced but not well documented or compared. This paper provides a review and comparison of methods in target exclusion, spatial subsetting and spectral pre-clustering, and introduces a new technique which combines these methods. The analysis provides insight into the merit of employing unstructured background characterization techniques, as well as limitations for their practical application

    Gel transitions in colloidal suspensions

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    The idealized mode coupling theory (MCT) is applied to colloidal systems interacting via short-range attractive interactions of Yukawa form. At low temperatures MCT predicts a slowing down of the local dynamics and ergodicity breaking transitions. The nonergodicity transitions share many features with the colloidal gel transition, and are proposed to be the source of gelation in colloidal systems. Previous calculations of the phase diagram are complemented with additional data for shorter ranges of the attractive interaction, showing that the path of the nonergodicity transition line is then unimpeded by the gas-liquid critical curve at low temperatures. Particular attention is given to the critical nonergodicity parameters, motivated by recent experimental measurements. An asymptotic model is developed, valid for dilute systems of spheres interacting via strong short-range attractions, and is shown to capture all aspects of the low temperature MCT nonergodicity transitions.Comment: 12 pages, LaTeX, 5 eps figures, uses ioplppt.sty, to appear in J. Phys.: Condens. Matte

    Categorizing Health Outcomes and Efficacy of mHealth Apps for Persons With Cognitive Impairment: A Systematic Review

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    Background Use of mobile health (mHealth) apps is growing at an exponential rate in the United States and around the world. Mild cognitive impairment (MCI), Alzheimer disease, and related dementias are a global health problem. Numerous mHealth interventions exist for this population, yet the effect of these interventions on health has not been systematically described. Objective The aim of this study is to catalog the types of health outcomes used to measure effectiveness of mHealth interventions and assess which mHealth interventions have been shown to improve the health of persons with MCI, Alzheimer disease, and dementia. Methods We searched 13 databases, including Ovid MEDLINE, PubMed, EMBASE, the full Cochrane Library, CINAHL, PsycINFO, Ei Compendex, IEEE Xplore, Applied Science & Technology Source, Scopus, Web of Science, ClinicalTrials.gov, and Google Scholar from inception through May 2017 for mHealth studies involving persons with cognitive impairment that were evaluated using at least one quantitative health outcome. Proceedings of the Annual ACM Conferences on Human Factors in Computing Systems, the ACM User Interface Software and Technology Symposium, and the IEEE International Symposium on Wearable Computers were searched in the ACM Digital Library from 2012 to 2016. A hand search of JMIR Publications journals was also completed in July 2017. Results After removal of duplicates, our initial search returned 3955 records. Of these articles, 24 met final inclusion criteria as studies involving mHealth interventions that measured at least one quantitative health outcome for persons with MCI, Alzheimer disease, and dementia. Common quantitative health outcomes included cognition, function, mood, and quality of life. We found that 21.2% (101/476) of the fully reviewed articles were excluded because of a lack of health outcomes. The health outcomes selected were observed to be inconsistent between studies. For those studies with quantitative health outcomes, more than half (58%) reported postintervention improvements in outcomes. Conclusions Results showed that many mHealth app interventions targeting those with cognitive impairment lack quantitative health outcomes as a part of their evaluation process and that there is a lack of consensus as to which outcomes to use. The majority of mHealth app interventions that incorporated health outcomes into their evaluation noted improvements in the health of persons with MCI, Alzheimer disease, and dementia. However, these studies were of low quality, leading to a grade C level of evidence. Clarification of the benefits of mHealth interventions for people with cognitive impairment requires more randomized controlled trials, larger numbers of participants, and trial designs that minimize bias. Trial Registration PROSPERO Registration: PROSPERO 2016:CRD42016033846; http://www.crd.york.ac.uk/PROSPERO/ display_record.asp?ID=CRD42016033846 (Archived by WebCite at http://www.webcitation.org/6sjjwnv1M

    Hydraulic resistance to overland flow on surfaces with partially submerged vegetation

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96239/1/wrcr13661.pd

    Morphodynamics of a width-variable gravel bed stream: new insights on pool-riffle formation from physical experiments

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    Field observations, experiments, and numerical simulations suggest that pool-riffles along gravel bed mountain streams develop due to downstream variations of channel width. Where channels narrow, pools are observed, and at locations of widening, riffles occur. Based on previous work, we hypothesize that the bed profile is coupled to downstream width variations through momentum fluxes imparted to the channel surface, which scale with downstream changes of flow velocity. We address this hypothesis with flume experiments understood through scaling theory. Our experiments produce pool-riffle like structures across average Shields stresses t* that are a factor 1.5–2 above the threshold mobility condition of the experimental grain size distribution. Local topographic responses are coupled to channel width changes, which drive flows to accelerate or decelerate on average, for narrowing and widening, respectively. We develop theory which explains the topography-width-velocity coupling as a ratio of two reinforcing timescales. The first timescale captures the time necessary to do work to the channel bed. The second timescale characterizes the relative time magnitude of momentum transfer from the flowing fluid to the channel bed surface. Riffle-like structures develop where the work and momentum timescales are relatively large, and pools form where the two timescales are relatively small. We show that this result helps to explain local channel bed slopes along pool-riffles for five data sets representing experimental, numerical, and natural cases, which span 2 orders of magnitude of reach-averaged slope. Additional model testing is warranted.Peer ReviewedPostprint (published version

    Interweaving PFASST and Parallel Multigrid

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    The parallel full approximation scheme in space and time (PFASST) introduced by Emmett and Minion in 2012 is an iterative strategy for the temporal parallelization of ODEs and discretized PDEs. As the name suggests, PFASST is similar in spirit to a space-time full approximation scheme multigrid method performed over multiple time steps in parallel. However, since the original focus of PFASST was on the performance of the method in terms of time parallelism, the solution of any spatial system arising from the use of implicit or semi-implicit temporal methods within PFASST have simply been assumed to be solved to some desired accuracy completely at each substep and each iteration by some unspecified procedure. It hence is natural to investigate how iterative solvers in the spatial dimensions can be interwoven with the PFASST iterations and whether this strategy leads to a more efficient overall approach. This paper presents an initial investigation on the relative performance of different strategies for coupling PFASST iterations with multigrid methods for the implicit treatment of diffusion terms in PDEs. In particular, we compare full accuracy multigrid solves at each substep with a small fixed number of multigrid V-cycles. This reduces the cost of each PFASST iteration at the possible expense of a corresponding increase in the number of PFASST iterations needed for convergence. Parallel efficiency of the resulting methods is explored through numerical examples
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