96 research outputs found

    A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

    Get PDF
    Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact

    Phase II study of S-1, a novel oral fluorouracil, in advanced non-small-cell lung cancer

    Get PDF
    The purpose of this study was to evaluate the efficacy and safety of a novel oral anticancer fluoropyrimidine derivative, S-1, in patients receiving initial chemotherapy for unresectable, advanced non-small-cell lung cancer (NSCLC). Between June 1996 and July 1998, 62 patients with NSCLC who had not received previous chemotherapy for advanced disease were enrolled in this study. 59 patients (22 stage IIIB and 37 stage IV) were eligible for the evaluation of efficacy and safety. S-1 was administered orally, twice daily, after meals. 3 dosages of S-1 were prescribed according to body surface area (BSA) so that they would be approximately equivalent to 80 mg m−2day−1: BSA < 1.25 m2, 40 mg b.i.d.; BSA≥1.25 but <1.5 m2; 50 mg b.i.d., and BSA≥1.5 m2: 60 mg b.i.d. One cycle consisted of consecutive administration of S-1 for 28 days followed by a 2-week rest period, and cycles were repeated up to 4 times. The partial response (PR) rate of the eligible patients was 22.0% (13/59); (95% confidence interval: 12.3–34.7%). A PR was observed in 22.7% (5/22) of the stage IIIB patients and 21.6% (8/37) of the stage IV patients. The median response duration was 3.4 months (1.1–13.7 months or longer). Grade 4 neutropenia was observed in one of the 59 patients (1.7%). The grade 3 or 4 toxicities consisted of decreased haemoglobin level in 1.7% of patients (1/59), neutropenia in 6.8% (4/59), thrombocytopenia in 1.7% (1/59), anorexia in 10.2% (6/59), diarrhoea in 8.5% (5/59), stomatitis in 1.7% (1/59), and malaise in 6.8% (4/59), and their incidences were relatively low. There were no irreversible, severe or unexpected toxicities. The median survival time (MST) of all patients was 10.2 months (95% confidence interval: 7.7–14.5 months), and the one-year survival rate was 41.1%. The MST of the stage IIIB patients was 7.9 months, and that of the stage IV patients was 11.1 months. The one-year survival rates of the stage IIIB and IV patients were 30.7% and 47.4%, respectively. S-1 was considered to be an active single agent against NSCLC. Further study of S-1 with other active agents is warranted. © 2001 Cancer Research Campaignhttp://www.bjcancer.co

    The rapid atmospheric monitoring system of the Pierre Auger Observatory

    Get PDF
    The Pierre Auger Observatory is a facility built to detect air showers produced by cosmic rays above 10(17) eV. During clear nights with a low illuminated moon fraction, the UV fluorescence light produced by air showers is recorded by optical telescopes at the Observatory. To correct the observations for variations in atmospheric conditions, atmospheric monitoring is performed at regular intervals ranging from several minutes (for cloud identification) to several hours (for aerosol conditions) to several days (for vertical profiles of temperature, pressure, and humidity). In 2009, the monitoring program was upgraded to allow for additional targeted measurements of atmospheric conditions shortly after the detection of air showers of special interest, e. g., showers produced by very high-energy cosmic rays or showers with atypical longitudinal profiles. The former events are of particular importance for the determination of the energy scale of the Observatory, and the latter are characteristic of unusual air shower physics or exotic primary particle types. The purpose of targeted (or 'rapid') monitoring is to improve the resolution of the atmospheric measurements for such events. In this paper, we report on the implementation of the rapid monitoring program and its current status. The rapid monitoring data have been analyzed and applied to the reconstruction of air showers of high interest, and indicate that the air fluorescence measurements affected by clouds and aerosols are effectively corrected using measurements from the regular atmospheric monitoring program. We find that the rapid monitoring program has potential for supporting dedicated physics analyses beyond the standard event reconstruction

    QCD and strongly coupled gauge theories : challenges and perspectives

    Get PDF
    We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe

    The Rapid Atmospheric Monitoring System of the Pierre Auger Observatory

    Get PDF
    The Pierre Auger Observatory is a facility built to detect air showers produced by cosmic rays above 10^17 eV. During clear nights with a low illuminated moon fraction, the UV fluorescence light produced by air showers is recorded by optical telescopes at the Observatory. To correct the observations for variations in atmospheric conditions, atmospheric monitoring is performed at regular intervals ranging from several minutes (for cloud identification) to several hours (for aerosol conditions) to several days (for vertical profiles of temperature, pressure, and humidity). In 2009, the monitoring program was upgraded to allow for additional targeted measurements of atmospheric conditions shortly after the detection of air showers of special interest, e.g., showers produced by very high-energy cosmic rays or showers with atypical longitudinal profiles. The former events are of particular importance for the determination of the energy scale of the Observatory, and the latter are characteristic of unusual air shower physics or exotic primary particle types. The purpose of targeted (or "rapid") monitoring is to improve the resolution of the atmospheric measurements for such events. In this paper, we report on the implementation of the rapid monitoring program and its current status. The rapid monitoring data have been analyzed and applied to the reconstruction of air showers of high interest, and indicate that the air fluorescence measurements affected by clouds and aerosols are effectively corrected using measurements from the regular atmospheric monitoring program. We find that the rapid monitoring program has potential for supporting dedicated physics analyses beyond the standard event reconstruction

    Multi-messenger observations of a binary neutron star merger

    Get PDF
    On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
    corecore