397 research outputs found

    Detecting ecological thresholds and tipping points in the natural capital assets of a protected coastal ecosystem.

    Get PDF
    Concern about abrupt and potentially irreversible ecosystem thresholds and tipping points is increasing, as they may have significant implications for natural capital and human wellbeing. Although well established in theory, there are few empirical studies that provide evidence for these phenomena in coastal and estuarine ecosystems, despite their high value for provision of ecosystem services. To determine the likelihood of such events, we tested two statistical methods; sequential T-test analysis (STARS) and generalised additive models (GAMs) in a harbour ecosystem. These methods were applied to time series data spanning up to 25 years coupled with analysis of the relationships between drivers and natural capital asset flows. Results of the STARS analysis identified nonlinear thresholds in three of the natural capital assets of Poole harbour; mudflat area, Manila clam stocks and wader/wildfowl numbers, as well as an increase in several drivers affecting the harbour. The most prominent threshold was recorded in the Manila clam fisheries of the harbour, with stocks in two locations of the harbour declining by 73–78% between 2006 and 2008. We suggest that the historic decline in the Manila clam stocks of the harbour were partly attributable to illegal fishing pressure although other factors such as disease and lease bed holders switching to other species were also likely to have contributed. More recently (2015-onwards) wild clam stocks of the harbour have increased thanks to improved management measures by local authorities. Generalised additive models also identified the contribution of macroalgal mats, sediment shoaling and river flows to historic changes in mudflat area, saltmarsh area and wader/wildfowl numbers. We conclude that information on thresholds and tipping points obtained using these approaches can potentially be of value in a management context, by focusing attention on the interactions and positive feedbacks between drivers that may cause abrupt change in coastal ecosystems

    Geographical origin of dabbling ducks wintering in Iberia: Sex differences and implications for pair formation

    Get PDF
    Los humedales ibéricos naturales y antropógenos del sur de Europa son bien conocidos por sustentar a un gran número de aves migratorias acuáticas del Palaearctico en cada invierno. Sin embargo, la información sobre el origen geográfico de los patos de humedal que pasan el invierno en estos espacios es escasa y se limita principalmente a datos de sonar. Aquí, hemos utilizado marcadores isotópicos para determinar el origen geográfico de machos y hembras de Pintails septentrional, Anas acuta y Anas crecca euroasiática en Extremadura, en el interior de la península Ibérica, sitio clave para invernar los patos de humedal. Además, hemos instalado seis etiquetas GPSGSM en Pintails septentrional para complementar los datos derivados del análisis de isótopos estables. La mayoría (> 70%) de los Pintails septentrional, dentro del primer año calendario, fueron asignados a regiones situadas por encima de los 55° N, volando 2600-5600 km desde sus regiones de procedencia a Extremadura. Los valores promedio de δ2Hf variaron significativamente entre macho y hembra de Pintails septentrional, sugiriendo que los sexos tienen diferentes orígenes geográficos. Los datos de los adultos etiquetados Pintails septentrional apoyan los datos isotópicos, un macho volando más de 5000 km de la costa de la mar Pechora (Rusia). La mayoría (> 70%) de los Teal euroasiáticos, dentro del primer año calendario, fueron asignados a la región situada entre 48° y 60° N y viajaron 1500-4500 km para llegar en Extremadura. Los machos y hembras de Cerceta euroasiáticos mostraron diferencias marginales en valores promedio de δ2Hf. En patos de humedal migratorios, el emparejamiento se produce normalmente en las zonas de invernada, y los patos en su primer invierno pueden reproducirse en la primavera siguiente. Para Pintails septentrional, la formación de parejas en Extremadura podría suceder entre individuos con diferentes orígenes geográficos, lo que podría contribuir a la variabilidad genética de su descendencia.Natural and anthropogenic Iberian wetlands in southern Europe are well known for supporting large numbers of migratory Palaearctic waterbirds each winter. However, information on the geographical origin of dabbling ducks overwintering in these wetlands is scarce and mostly limited to data from ringing recoveries. Here, we used intrinsic isotopic markers to determine the geographical origin of male and female Northern Pintails Anas acuta and Eurasian Teal Anas crecca in Extremadura, inland Iberia, a key site for overwintering dabbling ducks. Additionally, we fitted six Northern Pintails with GPSGSM tags to complement the data derived from stable isotope analysis. Most (> 70%) first calendar-year Northern Pintails were assigned to regions above 55°N, flying 2600–5600 km from their main natal regions to Extremadura. Mean values of δ2Hf varied significantly between male and female Northern Pintails, suggesting that the sexes had different geographical origins. Data from tagged adult Northern Pintails supported the isotopic data, one male flying more than 5000 km to the coast of the Pechora Sea (Russia). Most (> 70%) first calendar-year Eurasian Teal were assigned to the region between 48° and 60°N, travelling 1500–4500 km to arrive in Extremadura. Male and female Eurasian Teal showed marginal differences in mean values of δ2Hf. In migratory dabbling ducks, pairing typically occurs on the wintering grounds, and ducks in their first winter can breed the following spring. For Northern Pintails, pair formation in Extremadura could occur between individuals with different geographical origins, which could contribute to the genetic variability of their offspring.Trabajo patrocinado por: Junta de Extremadura. Proyecto PRI 09C128 Gobierno de Extremadura y Fondos FEDER. Ayuda GR10174 Confederación Hidrográfica del Guadiana (Ministerio de Medio Ambiente). Ayuda financierapeerReviewe

    Visible-light photoredox catalysis enables the biomimetic synthesis of nyingchinoids A, B, and D, and rasumatranin D

    Get PDF
    German editionThe total synthesis of nyingchinoids A and B has been achieved through successive rearrangements of a 1,2-dioxane intermediate that was assembled using a visible-light photoredox-catalysed aerobic [2+2+2] cycloaddition. Nyingchinoid D was synthesised with a competing [2+2] cycloaddition. Based on NMR data and biosynthetic speculation, we proposed a structure revision of the related natural product rasumatranin D, which was confirmed through total synthesis. Under photoredox conditions, we observed the conversion of a cyclobutane into a 1,2-dioxane through retro-[2+2] cycloaddition followed by aerobic [2+2+2] cycloaddition.Jacob D. Hart, Laura Burchill, Aaron J. Day, Christopher G. Newton, Christopher J. Sumby, David M. Huang, and Jonathan H. Georg

    Development and external validation study of a melanoma risk prediction model incorporating clinically assessed naevi and solar lentigines

    Get PDF
    Background: Melanoma risk prediction models could be useful for matching preventive interventions to patients’ risk. Objectives: To develop and validate a model for incident first‐primary cutaneous melanoma using clinically assessed risk factors. Methods: We used unconditional logistic regression with backward selection from the Australian Melanoma Family Study (461 cases and 329 controls) in which age, sex and city of recruitment were kept in each step, and we externally validated it using the Leeds Melanoma Case–Control Study (960 cases and 513 controls). Candidate predictors included clinically assessed whole‐body naevi and solar lentigines, and self‐assessed pigmentation phenotype, sun exposure, family history and history of keratinocyte cancer. We evaluated the predictive strength and discrimination of the model risk factors using odds per age‐ and sex‐adjusted SD (OPERA) and the area under curve (AUC), and calibration using the Hosmer–Lemeshow test. Results: The final model included the number of naevi ≥ 2 mm in diameter on the whole body, solar lentigines on the upper back (a six‐level scale), hair colour at age 18 years and personal history of keratinocyte cancer. Naevi was the strongest risk factor; the OPERA was 3·51 [95% confidence interval (CI) 2·71–4·54] in the Australian study and 2·56 (95% CI 2·23–2·95) in the Leeds study. The AUC was 0·79 (95% CI 0·76–0·83) in the Australian study and 0·73 (95% CI 0·70–0·75) in the Leeds study. The Hosmer–Lemeshow test P‐value was 0·30 in the Australian study and < 0·001 in the Leeds study. Conclusions: This model had good discrimination and could be used by clinicians to stratify patients by melanoma risk for the targeting of preventive interventions. What's already known about this topic? Melanoma risk prediction models may be useful in prevention by tailoring interventions to personalized risk levels. For reasons of feasibility, time and cost many melanoma prediction models use self‐assessed risk factors. However, individuals tend to underestimate their naevus numbers. What does this study add? We present a melanoma risk prediction model, which includes clinically‐assessed whole‐body naevi and solar lentigines, and self‐assessed risk factors including pigmentation phenotype and history of keratinocyte cancer. This model performs well on discrimination, the model's ability to distinguish between individuals with and without melanoma, and may assist clinicians to stratify patients by melanoma risk for targeted preventive interventions

    The analgesic effect of electroencephalographic neurofeedback for people with chronic pain: protocol for a systematic review and meta-analysis

    Get PDF
    Background: Chronic pain is a global health problem, affecting around 1 in 5 individuals in the general population. The understanding of the key role of functional brain alterations in the generation of chronic pain has led researchers to focus on pain treatments that target brain activity. Electroencephalographic neurofeedback attempts to modulate the power of maladaptive electroencephalography frequency powers to decrease chronic pain. Although several studies have provided promising evidence, the effect of electroencephalographic neurofeedback on chronic pain is uncertain. Objective: This systematic review aims to synthesize the evidence from randomized controlled trials to evaluate the analgesic effect of electroencephalographic neurofeedback. In addition, we will synthesize the findings of nonrandomized studies in a narrative review. Methods: We will apply the search strategy in 5 electronic databases (Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PsycInfo, and CINAHL) for published studies and in clinical trial registries for completed unpublished studies. We will include studies that used electroencephalographic neurofeedback as an intervention for people with chronic pain. Risk-of-bias tools will be used to assess methodological quality of the included studies. We will include randomized controlled trials if they have compared electroencephalographic neurofeedback with any other intervention or placebo control. The data from randomized controlled trials will be aggregated to perform a meta-analysis for quantitative synthesis. The primary outcome measure is pain intensity assessed by self-report scales. Secondary outcome measures include depressive symptoms, anxiety symptoms, and sleep quality measured by self-reported questionnaires. We will investigate the studies for additional outcomes addressing adverse effects and resting-state electroencephalography analysis. Additionally, all types of nonrandomized studies will be included for a narrative synthesis. The intended and unintended effects of nonrandomized studies will be extracted and summarized in a descriptive table. Results: Ethics approval is not required for a systematic review, as there will be no patient involvement. The search for this systematic review commenced in July 2020, and we expect to publish the findings in early 2021. Conclusions: This systematic review will provide recommendations for researchers and health professionals, as well as people with chronic pain, about the evidence for the analgesic effect of electroencephalographic neurofeedback. Trial Registration: International Prospective Register of Systematic Reviews (PROSPERO) CRD42020177608; https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=177608 International Registered Report Identifier (IRRID): PRR1-10.2196/2282

    Polarisation of equine pregnancy outcome associated with a maternal MHC class I allele: preliminary evidence

    Get PDF
    Identification of risk factors which are associated with severe clinical signs can assist in the management of disease outbreaks and indicate future research areas. Pregnancy loss during late gestation in the mare compromises welfare, reduces fecundity and has financial implications for horse owners. This retrospective study focussed on the identification of risk factors associated with pregnancy loss among 46 Thoroughbred mares on a single British stud farm, with some but not all losses involving equid herpesvirus-1 (EHV-1) infection. In a sub-group of 30 mares, association between pregnancy loss and the presence of five common Thoroughbred horse haplotypes of the equine Major Histocompatibility Complex (MHC) was assessed. This involved development of sequence specific, reverse transcriptase polymerase chain reactions and in several mares, measurement of cytotoxic T lymphocyte activity. Of the 46 mares, 10 suffered late gestation pregnancy loss or neonatal foal death, five of which were EHV-1 positive. Maternal factors including age, parity, number of EHV-1 specific vaccinations and the number of days between final vaccination and foaling or abortion were not significantly associated with pregnancy loss. In contrast, a statistically significant association between the presence of the MHC class I B2 allele and pregnancy loss was identified, regardless of the fetus / foal’s EHV-1 status (p=0.002). In conclusion, this study demonstrated a significantly positive association between pregnancy loss in Thoroughbred mares and a specific MHC class I allele in the mother. This association requires independent validation and further investigation of the mechanism by which the mare’s genetic background contributes to pregnancy outcome

    Relativistic Calculation of the Meson Spectrum: a Fully Covariant Treatment Versus Standard Treatments

    Full text link
    A large number of treatments of the meson spectrum have been tried that consider mesons as quark - anti quark bound states. Recently, we used relativistic quantum "constraint" mechanics to introduce a fully covariant treatment defined by two coupled Dirac equations. For field-theoretic interactions, this procedure functions as a "quantum mechanical transform of Bethe-Salpeter equation". Here, we test its spectral fits against those provided by an assortment of models: Wisconsin model, Iowa State model, Brayshaw model, and the popular semi-relativistic treatment of Godfrey and Isgur. We find that the fit provided by the two-body Dirac model for the entire meson spectrum competes with the best fits to partial spectra provided by the others and does so with the smallest number of interaction functions without additional cutoff parameters necessary to make other approaches numerically tractable. We discuss the distinguishing features of our model that may account for the relative overall success of its fits. Note especially that in our approach for QCD, the resulting pion mass and associated Goldstone behavior depend sensitively on the preservation of relativistic couplings that are crucial for its success when solved nonperturbatively for the analogous two-body bound-states of QED.Comment: 75 pages, 6 figures, revised content

    Analysis of LIGO data for gravitational waves from binary neutron stars

    Get PDF
    We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of R<\mathcal{R}<1.7 \times 10^{2}peryearperMilkyWayEquivalentGalaxy(MWEG),with90coalescencerateofbinarysystemsinwhicheachcomponenthasamassintherange13 per year per Milky Way Equivalent Galaxy (MWEG), with 90% confidence, on the coalescence rate of binary systems in which each component has a mass in the range 1--3 M_\odot$.Comment: 17 pages, 9 figure

    Low Q^2 Jet Production at HERA and Virtual Photon Structure

    Get PDF
    The transition between photoproduction and deep-inelastic scattering is investigated in jet production at the HERA ep collider, using data collected by the H1 experiment. Measurements of the differential inclusive jet cross-sections dsigep/dEt* and dsigmep/deta*, where Et* and eta* are the transverse energy and the pseudorapidity of the jets in the virtual photon-proton centre of mass frame, are presented for 0 < Q2 < 49 GeV2 and 0.3 < y < 0.6. The interpretation of the results in terms of the structure of the virtual photon is discussed. The data are best described by QCD calculations which include a partonic structure of the virtual photon that evolves with Q2.Comment: 20 pages, 5 Figure

    Hadron Production in Diffractive Deep-Inelastic Scattering

    Get PDF
    Characteristics of hadron production in diffractive deep-inelastic positron-proton scattering are studied using data collected in 1994 by the H1 experiment at HERA. The following distributions are measured in the centre-of-mass frame of the photon dissociation system: the hadronic energy flow, the Feynman-x (x_F) variable for charged particles, the squared transverse momentum of charged particles (p_T^{*2}), and the mean p_T^{*2} as a function of x_F. These distributions are compared with results in the gamma^* p centre-of-mass frame from inclusive deep-inelastic scattering in the fixed-target experiment EMC, and also with the predictions of several Monte Carlo calculations. The data are consistent with a picture in which the partonic structure of the diffractive exchange is dominated at low Q^2 by hard gluons.Comment: 16 pages, 6 figures, submitted to Phys. Lett.
    corecore