519 research outputs found

    New speleothem data from Molinos and Ejulve caves reveal Holocene hydrological variability in northeast Iberia

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    New speleothem records from northeastern Iberian caves provide data to explore the climatic patterns during the Holocene. We present delta C-13 and Mg/Ca from three speleothems from two different caves located in the Iberian Range allowing replication of the climatic signal for several millennia. Through the integration of those stalagmites covering since the Holocene onset to 2 ka, the early Holocene (11.7-8.5 ka) appears as the wettest interval. A marked change towards aridity is observed during the middle Holocene (8.5-4.8 ka) and an increase of humidity afterwards (4.8-2 ka). This three-part pattern, contrasting with other Iberian sequences, seems to be associated with the different role that seasonality has played in the response of different proxies (or records) to changes in water availability. Interpreting our speleothem records as changes in winter-spring precipitation along the Holocene allows reconciling previous data on hydrological variability from the western Mediterranean borderlands

    Cyprus' image—a sun and sea destination—as a detrimental factor to seasonal fluctuations. Exploration into motivational factors for holidaying in Cyprus

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    Cyprus is established as a summer destination. To aid the destination in developing its winter season as well, this research uses a qualitative inductive approach to explore the tourists’ current image of the island and their motivations of visiting it. The research indicates that the current image, which essentially portrays Cyprus as a sun-and-sea destination is thought to dissuade tourists from perceiving the island as a year-round destination. Nonetheless, increasing the pull factors of the destination through the development of unique special interest products can help in extending the tourism season as well as broaden its narrow image

    Comparison between the 5-day cosynch and 7-day estradiol-based protocols for synchronization of ovulation and timed artificial insemination in suckled BOS taurus BEEF cows

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    The objective was to compare pregnancy per AI and follicular dynamic in suckled Bos taurus beef cows treated with either a 7-day progesterone + estradiol-based protocol or a 5-day progesterone CoSynch protocol for timed artificial insemination (TAI) during four breeding seasons. We hypothesized that estrous cycle status, days postpartum (DPP), fat depth and plasma progesterone concentration differentially modify the effect of treatments. Every year, 9 days before initiation of each breeding season, cows were randomly assigned to one of two groups. Cows in the 7-d P + E group (n = 428) received a progesterone intravaginal device (DIB) and estradiol benzoate on Day −9. On Day −2 the device was removed, and cows received cloprostenol and estradiol cypionate. Forty-eight hours later (Day 0) cows received TAI. Cows in the 5-d P + CoS group (n = 428) received a DIB, and GnRH on Day −8. On Day −3, the device was removed, and cows received cloprostenol. A second dose of cloprostenol was given on Day −2. Cows received GnRH and TAI 72 h after device removal (Day 0). On Day −9, estrous cycle status was determined. In a subset of cows (n = 79) the size of the dominant follicle was determined between Days −2 and 0. In another subset of cows (n = 340), DPP, fat depth (mm) and plasma progesterone concentration (ng/mL) were evaluated on Day −9. Pregnancy per AI was determined 30 d after TAI. Pregnancy per AI was greater for cows in the 5-d P + CoS group than for cows in the 7-d P + E group (50.9% vs. 41.3%, P = 0.01) and was also greater in cyclic than in anestrus cows (54.3% vs. 33.2%, P < 0.0001). There was also a significant effect of breeding season (P = 0.0002) and sire (P = 0.03), and an interaction between treatment group and breeding season (P = 0.03). The dominant follicle was larger (P < 0.0001) in cows in the 5-d P + CoS group than the 7-d P + E group (10.7 ± 0.29 mm vs. 9.0 ± 0.28 mm). Pregnancy per AI was greater in cows with ≥55 DPP (47.0% vs. 29.6%, P = 0.001), fat depth ≥0.50 mm (44.7% vs. 29.7%), and with plasma progesterone concentration ≥1 ng/mL (47.2% vs. 28.7%, P = 0.01). In cows with plasma progesterone ≥1 ng/mL on Day −9, pregnancy per AI was greater in the 5-d P + CoS group (60.5%) than in the 7-d P + E group (34.9%), but there was no difference between treatment groups in cows with plasma progesterone < 1 ng/mL (P = 0.07). In conclusion, the 5-d P + CoS protocol resulted in greater size of the dominant follicle and pregnancy per AI in suckled Bos taurus beef cows subjected to TAI.Fil: Bilbao, María Guillermina. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; ArgentinaFil: Zapata, Luis Oscar. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Romero Harry, H.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis. Estación Experimental Agropecuaria Anguil; ArgentinaFil: Perez Wallace, S.. Zoetis SRL; ArgentinaFil: Farcey, Maria Florencia. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; ArgentinaFil: Gelid, Lucas Fernando. Instituto Nacional de Tecnología Agropecuaria. Centro Regional La Pampa-San Luis. Estación Experimental Agropecuaria Anguil; ArgentinaFil: Palomares, R. A.. University of Georgia. College of Veterinary Medicine; Estados UnidosFil: Ferrer, M. S.. University of Georgia. College of Veterinary Medicine; Estados UnidosFil: Bartolome, Julian. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias; Argentin

    Measurement of the beam-helicity asymmetry II^{\odot} in the photoproduction of π0π±\pi^0\pi^{\pm}-pairs off protons and off neutrons

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    Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of mixed-charge pion pairs in the reactions γpnπ0π+\boldsymbol{\gamma}p\rightarrow n\pi^0\pi^+ off free protons and γd(p)pπ0π\boldsymbol{\gamma}d\rightarrow (p)p\pi^0\pi^- and γd(n)nπ0π+\boldsymbol{\gamma}d\rightarrow (n)n\pi^0\pi^+ off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow-Mainz magnetic spectrometer. The charged pions, recoil protons, recoil neutrons, and decay photons from π0\pi^0 mesons were detected in the 4π\pi electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. Using a complete kinematic reconstruction of the final state, excellent agreement was found between the results for free and quasi-free protons, suggesting that the quasi-free neutron results are also a close approximation of the free-neutron asymmetries. A comparison of the results to the predictions of the Two-Pion-MAID reaction model shows that the reaction mechanisms are still not well understood, in particular at low incident photon energies in the second nucleon-resonance region.Comment: accepted for publication in Eur. phys. J.

    K+ΛK^+\Lambda and K+Σ0K^+\Sigma^0 photoproduction with fine center-of-mass energy resolution

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    Measurements of γpK+Λ\gamma p \rightarrow K^{+} \Lambda and γpK+Σ0\gamma p \rightarrow K^{+} \Sigma^0 cross-sections have been obtained with the photon tagging facility and the Crystal Ball calorimeter at MAMI-C. The measurement uses a novel K+K^+ meson identification technique in which the weak decay products are characterized using the energy and timing characteristics of the energy deposit in the calorimeter, a method that has the potential to be applied at many other facilities. The fine center-of-mass energy (WW) resolution and statistical accuracy of the new data results in a significant impact on partial wave analyses aiming to better establish the excitation spectrum of the nucleon. The new analyses disfavor a strong role for quark-diquark dynamics in the nucleon.Comment: 7 pages, 8 figure

    Measurements of double-polarized compton scattering asymmetries and extraction of the proton spin polarizabilities

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    The spin polarizabilities of the nucleon describe how the spin of the nucleon responds to an incident polarized photon. The most model-independent way to extract the nucleon spin polarizabilities is through polarized Compton scattering. Double-polarized Compton scattering asymmetries on the proton were measured in the Δ(1232) region using circularly polarized incident photons and a transversely polarized proton target at the Mainz Microtron. Fits to asymmetry data were performed using a dispersion model calculation and a baryon chiral perturbation theory calculation, and a separation of all four proton spin polarizabilities in the multipole basis was achieved. The analysis based on a dispersion model calculation yields γE1E1=−3.5±1.2, γM1M1=3.16±0.85, γE1M2=−0.7±1.2, and γM1E2=1.99±0.29, in units of 10−4  fm4

    Photoproduction of π0\pi^0-pairs off protons and off neutrons

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    Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of π0π0\pi^0\pi^0 pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557~MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400~MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15\%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final state invariant masses up to \approx1550~MeV), where both reactions are dominated by the N(1520)3/2Δ(1232)3/2+πN(1520)3/2^-\rightarrow \Delta(1232)3/2^+\pi decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an NNσN^{\star}\rightarrow N\sigma decay for the proton, while the reaction is dominated by a sequential decay via a Δπ\Delta\pi intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled channel analysis.Comment: accepted for publication in Eur. Phys. J.

    The isospin structure of photoproduction of pi-eta pairs from the nucleon in the threshold region

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    Photoproduction of πη\pi\eta-pairs from nucleons has been investigated from threshold up to incident photon energies of \approx~1.4~GeV. The quasi-free reactions γppπ0η\gamma p\rightarrow p\pi^0\eta, γnnπ0η\gamma n\rightarrow n\pi^0\eta, γpnπ+η\gamma p\rightarrow n\pi^+\eta, and γnpπη\gamma n\rightarrow p\pi^-\eta were for the first time measured from nucleons bound in the deuteron. The corresponding reactions from a free-proton target were also studied to investigate final-state interaction effects (for neutral pions the free-proton results could be compared to previous measurements; the γpnπ+η\gamma p\rightarrow n\pi^+\eta reaction was measured for the first time). For the π0η\pi^0\eta final state coherent production via the γddπ0η\gamma d\rightarrow d\pi^0\eta reaction was also investigated. The experiments were performed at the tagged photon beam of the Mainz MAMI accelerator using an almost 4π4\pi coverage electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. The total cross sections for the four different final states obey the relation σ(pπ0η)\sigma(p\pi^0\eta) \approx σ(nπ0η)\sigma(n\pi^0\eta) \approx 2σ(pπη)2\sigma(p\pi^-\eta) \approx 2σ(nπ+η)2\sigma(n\pi^+\eta) as expected for a dominant contribution from a ΔηΔ(1232)πηN\Delta^{\star}\rightarrow\eta\Delta(1232)\rightarrow\pi\eta N reaction chain, which is also supported by the shapes of the invariant-mass distributions of nucleon-meson and π\pi-η\eta pairs. The experimental results are compared to the predictions from an isobar reaction model.Comment: accepted for publication in Phys. Lett.

    Photoproduction of pi0-mesons off neutrons in the nucleon resonance region

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    Precise angular distributions have been measured for the first time for the photoproduction of π0\pi^{0}-mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasi-free protons bound in the deuteron to the results for free protons and then applied as a correction to the quasi-free neutron data. The experiment was performed at the tagged photon facility of the Mainz Microtron MAMI with the Crystal Ball and TAPS detector setup for incident photon energies between 0.450.45~GeV and 1.41.4~GeV. The results are compared to the predictions from reaction models and partial-wave analyses based on data from other isospin channels. The model predictions show large discrepancies among each other and the present data will provide much tighter constraints. This is demonstrated by the results of a new analysis in the framework of the Bonn-Gatchina coupled-channel analysis which included the present data.Comment: accepted for publication in Phys; Rev. Let

    Photoproduction of π0-pairs off protons and off neutrons

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    Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of π0π0 pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final-state invariant masses up to ≈1550 MeV), where both reactions are dominated by the N(1520)3/2−→Δ(1232)3/2+π decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an N⋆→Nσ decay for the proton, while the reaction is dominated by a sequential decay via a Δπ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis
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