1,190 research outputs found
A Sobolev Poincar\'e type inequality for integral varifolds
In this work a local inequality is provided which bounds the distance of an
integral varifold from a multivalued plane (height) by its tilt and mean
curvature. The bounds obtained for the exponents of the Lebesgue spaces
involved are shown to be sharp.Comment: v1: 27 pages, no figures; v2: replaced citations of the author's
dissertation by proofs, material of sections 1 and 3 reorganised, slightly
more general results in section 2, some remarks, some discussion and some
references added, 40 pages, no figure
Effectiveness of flufenacet in controlling resistant black-grass (Alopecurus myosuroides Huds.) – comparison of glasshouse and field trial results
In the last years in practice, soil acting herbicides have become the backbone for the control of heavy infestations of grass weed populations. The known unsteady efficacy of HRAC group K1, K3 and N herbicides is controversially discussed and became linked with the development of herbicide resistance. In general, the testing of soil-acting compounds even under controlled glasshouse conditions as well as the confirmation of possible resistance is difficult and needs specific methods and a careful result interpretation. The reliability of test methods is therefore of extreme importance. The reference testing procedure such as plant density, irrigation and temperature conditions have been shown to influence the activity of the soil applied herbicides and to result in extreme differences in the efficacy levels in general, but also in differences between resistant and susceptible biotypes.In our trials, the seed density could be ranked as the most sensitive factor. Of the tested products, Cadou SC was the most consistent herbicide followed by Boxer and Stomp Aqua. Possible reduced efficacy effects in glasshouse trials could not be verified by field trial results. The evaluation of field trials from Northern Germany did not show a significant decrease in sensitivity of black-grass (Alopecurus myosuroides Huds.) to flufenacet or flufenact plus diflufenican. It could be shown that seasonal variation in soil moisture, amount of rainfall, temperature conditions and application timing all influenced the efficacy level in the field the most. Keywords: Enhanced metabolic resistance, herbicide resistance, pendimethalin, prosulfocarb, soil herbicides, test methodologyWirksamkeit von Flufenacet in der Bekämpfung von resistentem Ackerfuchsschwanz (Alopecurus myosuroides Huds.) – Vergleich von Ergebnissen aus Gewächshaus- und FeldversuchenIn den letzten Jahren ist die Anwendung von Bodenherbiziden zu einem zentralen Baustein für die Bekämpfung von hohen Ungrasdichten in der landwirtschaftlichen Praxis geworden. Die schwankende Wirkungssicherheit der Bodenherbizide der HRAC Gruppen K1, K3 und N unter praktischen Feldbedingungen wird teilweise konträr diskutiert und oft mit einer möglichen Resistenzentwicklung in Zusammenhang gebracht. Die allgemeine Untersuchung der Wirksamkeit von Bodenherbiziden unter kontrollierten Gewächshausbedingungen ist schwierig und bedarf einer wirkstoffspezifischen Methodenanpassung und einer entsprechenden überlegten Ergebnisauswertung. Die Vertrauenswürdigkeit der Testmethode ist deshalb von besonderer Bedeutung. Die Vielzahl der Methodenparameter, wie unter anderem Pflanzendichte, Bewässerung und Temperaturbedingungen, beeinflussen die Wirksamkeit der Bodenherbizide und können zu hohen Wirkungsunterschieden im Allgemeinen, aber auch zu Unterschieden zwischen verschiedenen Populationen führen.In der Überprüfung der Methodenparameter stellte sich vor allem die Pflanzendichte als einflussreicher Faktor für die Wirkungsstärke der Bodenherbizide heraus. In der Reihenfolge der getesteten Produkte war Cadou SC das wirkungsstärkste und konsistenteste Produkt, gefolgt von Boxer und Stomp Aqua. Wirkungsunterschiede in den Gewächshausuntersuchungen konnten im Allgemeinen mit den Feldergebnissen nicht bestätigt werden. Eine Auswertung von Feldversuchen aus Resistenzgebieten in Norddeutschland zeigte in den letzten Jahren keine signifikante Abnahme der Wirksamkeit von Flufenacet oder Flufenacet plus Diflufenican in der Bekämpfungsleistung von Ackerfuchsschwanz (Alopecurus myosuroides Huds.). Jahreszeitliche Einflussfaktoren wie Bodenfeuchtigkeit, Niederschlagsereignisse, Temperaturbedingungen und das Wachstumsstadium der Ungräser zum Zeitpunkt der Applikation zeigten einen eindeutigen Einfluss auf die Wirksamkeit der Bodenherbizide. Stichwörter: Bodenherbizide, Herbizidresistenz, Metabolische Resistenz, Pendimethalin, Prosulfocarb, Untersuchungsmethode
Evaluating the impact of U.S. Historical Climatology Network homogenization using the U.S. Climate Reference Network
Numerous inhomogeneities including station moves, instrument changes, and time of observation changes in the U.S. Historical Climatological Network (USHCN) complicate the assessment of long-term temperature trends. Detection and correction of inhomogeneities in raw temperature records have been undertaken by NOAA and other groups using automated pairwise neighbor comparison approaches, but these have proven controversial due to the large trend impact of homogenization in the United States. The new U.S. Climate Reference Network (USCRN) provides a homogenous set of surface temperature observations that can serve as an effective empirical test of adjustments to raw USHCN stations. By comparing nearby pairs of USHCN and USCRN stations, we find that adjustments make both trends and monthly anomalies from USHCN stations much more similar to those of neighboring USCRN stations for the period from 2004 to 2015 when the networks overlap. These results improve our confidence in the reliability of homogenized surface temperature records
Herbizidresistenz von Flughaferherkünften aus Rheinland-Pfalz
2011 wurden in Rheinland-Pfalz zwei und 2012 acht Flughafer-Samenproben (Avena fatua) von Flächen mit unzureichender Herbizidwirkung gesammelt. In zwei aufeinander folgenden Biotests wurden sie auf Herbizidresistenz getestet. Durch Behandlung mit Gibberellinsäure konnte die Entwicklung der Pflanzen vereinheitlicht werden. Geprüft wurden verschiedene ACCase-Hemmer (Ralon Super, Topik 100, Axial 50, Traxos, Focus Ultra) und ein ALS-Inhibitor (Husar OD). Bei drei der 10 Herkünfte waren Kreuzresistenzen gegen ACCase-Inhibitoren nachweisbar. Focus Ultra (Cycloxydim) war nicht betroffen. In zwei Herkünften war die gesamte Population betroffen, während sich Resistenzen bei der dritten Herkunft nur bei einzelnen Pflanzen zeigten. Die genetische Untersuchung ergab bei zwei Herkünften (2011) eine I1781L Target-Site-Mutation. Eine Population (2012) zeigte darüber hinaus die weiteren Target-Site-Mutationen W1999C, I2041V und C2088N. Die Minderwirkungen des ALS-Inhibitors bedürfen weiterer Untersuchungen mit abgestufter Aufwandmenge.Stichwörter: ACCase, ALS, Avena fatua, Biotest, Target-SiteHerbicide resistance of Wild Oat (Avena fatua) populations from Rhineland-PalatinateAbstractIn Rhineland-Palatinate two seed samples of Wild Oat (Avena fatua) were collected in 2011 and eight samples followed in 2012. They derived from fields with inadequate herbicide performance. In order to harmonise plant development, seeds were treated with gibberellic acid. Herbicide resistance was tested by means of two successive biotests using different ACCase-inhibitors (Ralon Super, Topik 100, Axial 50, Traxos, Focus Ultra) and one ALS-inhibitor (Husar OD). Three samples showed cross-resistance against ACCase-inhibitors, with the exception of Focus Ultra (Cycloxydim). Within two populations resistance was well established. Only single plants expressed resistance in a third sample. Genetic analysis found an I1781L target-site-mutation in two samples. One population showed additional mutations: W1999C, I2041V and C2088N. Further investigations, including different application rates, are necessary to explain the poor performance of the ALS-inhibitor.Keywords: ACCase, ALS, Avena fatua, biotest, target sit
Plasma amyloid concentration in Alzheimer's disease: performance of a high-throughput amyloid assay in distinguishing Alzheimer's disease cases from controls
BACKGROUND: Collection of cerebrospinal fluid (CSF) for measurement of amyloid-β (Aβ) species is a gold standard in Alzheimer's disease (AD) diagnosis, but has risks. Thus, establishing a low-risk blood Aβ test with high AD sensitivity and specificity is of outmost interest. OBJECTIVE: We evaluated the ability of a commercially available plasma Aβ assay to distinguish AD patients from biomarker-healthy controls. METHOD: In a case-control design, we examined plasma samples from 44 AD patients (A + N+) and 49 controls (A-N-) from a memory clinic. AD was diagnosed using a combination of neuropsychological examination, CSF biomarker analysis and brain imaging. Total Aβ40 and total Aβ42 in plasma were measured through enzyme-linked immunosorbent assay (ELISA) technology using ABtest40 and ABtest42 test kits (Araclon Biotech Ltd.). Receiver operating characteristic (ROC) analyses with outcome AD were performed, and sensitivity and specificity were calculated. RESULTS: Plasma Aβ42/40 was weakly positively correlated with CSF Aβ42/40 (Spearman's rho 0.22; p = 0.037). Plasma Aβ42/40 alone was not able to statistically significantly distinguish between AD patients and controls (AUC 0.58; 95% CI 0.46, 0.70). At a cut-point of 0.076 maximizing sensitivity and specificity, plasma Aβ42/40 had a sensitivity of 61.2% and a specificity of 63.6%. CONCLUSION: In this sample, the high-throughput blood Aβ assay was not able to distinguish well between AD patients and controls. Whether or not the assay may be useful in large-scale epidemiological settings remains to be seen
Recent advances in drug discovery for diabetic kidney disease
Introduction: Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease (ESRD), and 40% of patients with diabetes develop DKD. Although some pathophysiological mechanisms and drug targets of DKD have been described, the effectiveness or clinical usefulness of such treatment has not been well validated. Therefore, searching for new targets and potential therapeutic candidates has become an emerging research area. Areas covered: The pathophysiological mechanisms, new drug targets and potential therapeutic compounds for DKD are addressed in this review. Expert opinion: Although preclinical and clinical evidence has shown some positive results for controlling DKD progression, treatment regimens have not been well developed to reduce the mortality in patients with DKD globally. Therefore, the discovery of new therapeutic targets and effective target-based drugs to achieve better and safe treatment are urgently required. Preclinical screening and clinical trials for such drugs are needed
Living with a diagnosis of behavioural-variant frontotemporal dementia: The person’s experience.
YesResearch investigating behavioural-variant frontotemporal dementia has concentrated on identifying and quantifying people’s difficulties; yet few studies have considered how people with behavioural-variant frontotemporal dementia make sense of their difficulties. Five participants were interviewed and interpretive phenomenological analysis used to analyse the data. Two superordinate themes emerged: ‘Bewilderment’ and ‘Relationships with others’. ‘Bewilderment’ reflected the feelings of the participants from the start of their dementia, and was divided into two main themes (1) ‘Awareness of change: What’s the problem? and (2) Threats to self: This is not me. The superordinate theme, ‘Relationships with others’, reflected difficulties with social relationships and comprised two main themes (1) ‘Family and friends: Things haven’t changed… but do I say anything wrong?’ and (2) Coping with threats to self: Blame others or just avoid them. The themes were discussed in relation to literature evaluating the difficulties associated with behavioural-variant frontotemporal dementia together with implications for clinical practice
Flood realities, perceptions, and the depth of divisions on climate
Research has led to broad agreement among scientists that anthropogenic climate change is happening now and likely to worsen. In contrast to scientific agreement, US public views remain deeply divided, largely along ideological lines. Science communication has been neutralised in some arenas by intense counter-messaging, but as adverse climate impacts become manifest they might intervene more persuasively in local perceptions. We look for evidence of this occurring with regard to realities and perceptions of flooding in the northeastern US state of New Hampshire. Although precipitation and flood damage have increased, with ample news coverage, most residents do not see a trend. Nor do perceptions about past and future local flooding correlate with regional impacts or vulnerability. Instead, such perceptions follow ideological patterns resembling those of global climate change. That information about the physical world can be substantially filtered by ideology is a common finding from sociological environment/society research
Magnetoresistance of a two-dimensional electron gas with spatially periodic lateral modulations: Exact consequences of Boltzmann's equation
On the basis of Boltzmann's equation, and including anisotropic scattering in
the collision operator, we investigate the effect of one-dimensional
superlattices on two-dimensional electron systems. In addition to superlattices
defined by static electric and magnetic fields, we consider mobility
superlattices describing a spatially modulated density of scattering centers.
We prove that magnetic and electric superlattices in -direction affect only
the resistivity component if the mobility is homogeneous, whereas a
mobility lattice in -direction in the absence of electric and magnetic
modulations affects only . Solving Boltzmann's equation numerically,
we calculate the positive magnetoresistance in weak magnetic fields and the
Weiss oscillations in stronger fields within a unified approach.Comment: submitted to PR
Hemispheric and large-scale land surface air temperature variations: An extensive revision and an update to 2010
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