404 research outputs found

    Latitudinal variation in arrival and breeding phenology of the pied flycatcher Ficedula hypoleuca using large-scale citizen science data

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    Funding – TAM thanks partial support by CEAUL (funded by FCT – Fundação para a CiĂȘncia e a Tecnologia, Portugal, through the project UID/MAT/00006/2019).Many species have advanced the timing of annual reproductive cycles in response to climatic warming, sometimes leading to asynchrony between trophic levels, with negative population consequences. Long-distance migratory birds, reliant on short seasonal food pulses for breeding, are considered particularly susceptible to such disjunction because late arrival may preclude optimal timing of egg-laying. It is unknown whether the relative timing of arrival and egg-laying is sufficiently plastic, in time and space, to enable an adaptive response when arrival times change relative to local food resources. We used citizen science data, describing pied flycatcher Ficedula hypoleuca arrival and egg-laying dates, to explore temporal (2013–2016) and spatial (across Great Britain) variation in the phenology of arrival, laying and their difference. To assess the long-term trend in arrival and laying at a single location, we used data from a long-term field study. The arrival-laying interval was consistently shorter in the north, driven by the contrast between spatial variation in arrival date and spatial invariance in laying date. To understand whether a short arrival-laying interval may have consequences for productivity, we assessed the association between this interval and clutch size. We found no statistically significant correlation between these two variables. To examine long-term changes in arrival and laying dates, we focussed on a single location in southwestern England. Both dates of first male arrival and first egg laid in a season advanced since 1986, with no evidence of interval shortening. Together, our results demonstrate spatial and annual variation in the arrival-laying interval, with no detected effect on fecundity. Thus, the interval from arrival to laying is likely dictated by spatially and temporally varying local conditions, suggesting these migrant birds may have the ability to adapt this interval to align with local conditions and mitigate potential mismatch impacts.PostprintPeer reviewe

    A break in the clouds: connecting community experiences in Mosser, Cumbria

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    This photo essay accompanies a short film, A Break in the Clouds, which explores everyday life in Mosser, a small former township on the north-west edge of the Lake District. Prompted by the historical diaries of two eighteenth-century Quaker farmers from the same area, connections were drawn between the experiences of the current farmers and those in the past. The text discusses those connections, the making of the film, and how our approach was designed to democratise the research process. The images, selected by the photographer, reflect on the key themes or ‘spaces’ that emerged during the research: home/work, land/family, landscape/weather

    Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering

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    We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely-polarized 3 GeV electrons from unpolarized protons at Q^2 = 0.15, 0.25 (GeV/c)^2. The results are inconsistent with calculations solely using the elastic nucleon intermediate state, and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A_n provides a direct probe of the imaginary component of the 2-gamma exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.Comment: 5 pages, 3 figures, submitted to Physical Review Letters; shortened to meet PRL length limit, clarified some text after referee's comment

    Strange Quark Contributions to Parity-Violating Asymmetries in the Forward G0 Electron-Proton Scattering Experiment

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    We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12 < Q^2 < 1.0 GeV^2. These asymmetries, arising from interference of the electromagnetic and neutral weak interactions, are sensitive to strange quark contributions to the currents of the proton. The measurements were made at JLab using a toroidal spectrometer to detect the recoiling protons from a liquid hydrogen target. The results indicate non-zero, Q^2 dependent, strange quark contributions and provide new information beyond that obtained in previous experiments.Comment: 5 pages, 2 figure

    A High Statistics Search for Ultra-High Energy Gamma-Ray Emission from Cygnus X-3 and Hercules X-1

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    We have carried out a high statistics (2 Billion events) search for ultra-high energy gamma-ray emission from the X-ray binary sources Cygnus X-3 and Hercules X-1. Using data taken with the CASA-MIA detector over a five year period (1990-1995), we find no evidence for steady emission from either source at energies above 115 TeV. The derived upper limits on such emission are more than two orders of magnitude lower than earlier claimed detections. We also find no evidence for neutral particle or gamma-ray emission from either source on time scales of one day and 0.5 hr. For Cygnus X-3, there is no evidence for emission correlated with the 4.8 hr X-ray periodicity or with the occurrence of large radio flares. Unless one postulates that these sources were very active earlier and are now dormant, the limits presented here put into question the earlier results, and highlight the difficulties that possible future experiments will have in detecting gamma-ray signals at ultra-high energies.Comment: 26 LaTeX pages, 16 PostScript figures, uses psfig.sty to be published in Physical Review

    The G0 Experiment: Apparatus for Parity-Violating Electron Scattering Measurements at Forward and Backward Angles

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    In the G0 experiment, performed at Jefferson Lab, the parity-violating elastic scattering of electrons from protons and quasi-elastic scattering from deuterons is measured in order to determine the neutral weak currents of the nucleon. Asymmetries as small as 1 part per million in the scattering of a polarized electron beam are determined using a dedicated apparatus. It consists of specialized beam-monitoring and control systems, a cryogenic hydrogen (or deuterium) target, and a superconducting, toroidal magnetic spectrometer equipped with plastic scintillation and aerogel Cerenkov detectors, as well as fast readout electronics for the measurement of individual events. The overall design and performance of this experimental system is discussed.Comment: Submitted to Nuclear Instruments and Method

    Analysis of LIGO data for gravitational waves from binary neutron stars

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    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),with90coalescencerateofbinarysystemsinwhicheachcomponenthasamassintherange1−−3 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

    Seed dormancy and germination in Dodonaea viscosa (Sapindaceae) from south-western Saudi Arabia

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    Dodonaea viscosa (Sapindaceae) is widespread in the mountainous highlands of the southwestern part of the Kingdom of Saudi Arabia, where it is a medicinally important species for the people of Saudi Arabia. Seeds of this species were collected from Mount Atharb in the Al-Baha region, at an altitude of 2100 m. The aims of this study were to determine if the seeds of D. viscosa have physical dormancy (i.e. a water-impermeable seed coat) and, if so, what treatments would break dormancy, and what conditions promote germination after dormancy has been broken. The dormancy-breaking treatments included: soaking of seeds in concentrated sulfuric acid (H2SO4) for 10 minutes, immersion in boiling water for 10 minutes and exposure to 50 °C for 1 minute. After seeds had been pre-treated with H2SO4, to break dormancy, they were incubated at constant temperatures from 5 to 35°C, under 12-h photoperiods or in continuous darkness, and germination recorded. Salinity tolerance was investigated by incubating acid-scarified seeds in 0, 100, 200 and 300 mM NaCl in the light at 25°C. Untreated seeds had low final germination (30%). Seeds that had been acid-scarified, immersed in boiling water or exposed to 50 °C all achieved 91% subsequently when incubated at 25°C. Thus, seeds of this species in Saudi Arabia have physical dormancy, which can be broken by all three treatments designed to increase the permeability of the testa. After pre-treatment, there was a broad optimum constant temperature for germination that ranged between 5-25°C but germination was inhibited by higher temperatures (30 and 35°C). Light had little effect on this germination response. Scarified seeds were also sensitive to salinity, with the highest germination in distilled water and complete inhibition in 400 mM NaCl. Seeds that failed to germinate in saline treatments were mostly able to germinate on transfer to distilled water, suggesting osmotic inhibition

    Cell membrane damage induced by phenolic acids on wine lactic acid bacteria

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    The aim of this work was to investigate the effect of phenolic acids on cell membrane permeability of lactic acid bacteria from wine. Several phenolic acids were tested for their effects on the cell membrane of Oenococcus oeni and Lactobacillus hilgardii by measuring potassium and phosphate efflux, proton influx and by assessing culture viability employing a fluorescence technique based on membrane integrity. The experimental results indicate that hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids) induce greater ion leakages and higher proton influx than hydroxybenzoic acids (p-hydroxibenzoic, protocatechuic, gallic, vanillic, and syringic acids). Among the hydroxycinnamic acids, p-coumaric acid showed the strongest effect. Moreover, the exposure of cells to phenolic acids caused a significant decrease in cell culture viability, as measured by the fluorescence assay, in both tested strains. The results agree with previous results obtained in growth experiments with the same strains. Generally, phenolic acids increased the cell membrane permeability in lactic acid bacteria from wine. The different effects of phenolic acids on membrane permeability could be related to differences in their structure and lipophilic character
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