218 research outputs found

    Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar

    Get PDF
    Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tetheredballoon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2-3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds

    Energy calibration of the NEXT-White detector with 1% resolution near Q ββ of 136Xe

    Get PDF
    Excellent energy resolution is one of the primary advantages of electroluminescent high-pressure xenon TPCs. These detectors are promising tools in searching for rare physics events, such as neutrinoless double-beta decay (ββ0ν), which require precise energy measurements. Using the NEXT-White detector, developed by the NEXT (Neutrino Experiment with a Xenon TPC) collaboration, we show for the first time that an energy resolution of 1% FWHM can be achieved at 2.6 MeV, establishing the present technology as the one with the best energy resolution of all xenon detectors for ββ0ν searches. [Figure not available: see fulltext.

    Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield

    Get PDF
    High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and double beta decay detection. The discrimination of the rare event through the topological signature of primary ionisation trails is a major asset for this type of TPC when compared to single liquid or double-phase TPCs, limited mainly by the high electron diffusion in pure xenon. Helium admixtures with xenon can be an attractive solution to reduce the electron diffu- sion significantly, improving the discrimination efficiency of these optical TPCs. We have measured the electroluminescence (EL) yield of Xe–He mixtures, in the range of 0 to 30% He and demonstrated the small impact on the EL yield of the addition of helium to pure xenon. For a typical reduced electric field of 2.5 kV/cm/bar in the EL region, the EL yield is lowered by ∼ 2%, 3%, 6% and 10% for 10%, 15%, 20% and 30% of helium concentration, respectively. This decrease is less than what has been obtained from the most recent simulation framework in the literature. The impact of the addition of helium on EL statistical fluctuations is negligible, within the experimental uncertainties. The present results are an important benchmark for the simulation tools to be applied to future optical TPCs based on Xe-He mixtures. [Figure not available: see fulltext.]

    Near-intrinsic energy resolution for 30-662 keV gamma rays in a high pressure xenon electroluminescent TPC

    Get PDF
    We present the design, data and results from the NEXT prototype for Double Beta and Dark Matter (NEXT-DBDM) detector, a high-pressure gaseous natural xenon electroluminescent time projection chamber (TPC) that was built at the Lawrence Berkeley National Laboratory. It is a prototype of the planned NEXT-100 136Xe neutrino-less double beta decay (0νββ) experiment with the main objectives of demonstrating near-intrinsic energy resolution at energies up to 662 keV and of optimizing the NEXT-100 detector design and operating parameters. Energy resolutions of ∼1% FWHM for 662 keV gamma rays were obtained at 10 and 15 atm and ∼5% FWHM for 30 keV fluorescence xenon X-rays. These results demonstrate that 0.5% FWHM resolutions for the 2,459 keV hypothetical neutrino-less double beta decay peak are realizable. This energy resolution is a factor 7 to 20 better than that of the current leading 0νββ experiments using liquid xenon and thus represents a significant advancement. We present also first results from a track imaging system consisting of 64 silicon photo-multipliers recently installed in NEXT-DBDM that, along with the excellent energy resolution, demonstrates the key functionalities required for the NEXT-100 0νββ search

    Benefits of Entomophile Pollination in Crops of Brassica napus and Aspects of Plant Floral Biology

    Get PDF
    Rapeseed (Brassica napus L. var. oleifera) is an oleaginous species of the Brassicaceae family, being the third most produced oleaginous in the world. Rapeseed can produce fruits and seeds from both self-pollination and cross-pollination. However, cross-pollination rate is approximately 30% and may suffer variations due to the abundance and diversity of pollinator insects, cultivar and meteorological conditions. Different researchers have reported that pollination by insects, especially Apis mellifera honeybee, on rapeseed flowers provides an increase in productivity, improving yield and contributing to the uniformity and initial pod establishment. It is estimated that the economic value of A. mellifera honeybees for rapeseed cultivation in Brazil is US$ 8.2 million. The objective of this chapter is gathering data for a compilation of information regarding rapeseed culture and the importance of A. mellifera in Brassica napus pollination

    Estrategias de descontaminación de envases vacíos del herbicida glifosato en Entre Ríos

    Get PDF
    El glifosato es el herbicida con mayor volumen comercializado en Argentina, lo que genera gran cantidad de envases, con diferente grado de descontaminación. La empresa Spraytec posicionó la lanza Dualtec® (LSD) como método alternativo al triple lavado manual (TLM). Con la finalidad de conocer el grado de adopción de las prácticas de descontaminación de los envases vacíos de fitosanitarios y detectar residuos de glifosato en el agua de lavado mediante técnicas analíticas, se realizaron encuestas a productores agrícolas y a empresas expendedoras de fitosanitarios de Entre Ríos, bioensayos con semillas de lechuga y ensayos de efectividad de prácticas de lavado a través del Test ELISA. La mayoría de los productores agrícolas y operarios de pulverizadoras conoce el triple lavado. El grado de adopción de este último es variable, y se relaciona con el Departamento encuestado. El mayor porcentaje de productores y de empresas almacena los envases vacíos en sitios específicos. La lechuga fue altamente sensible a los cambios en las concentraciones de glifosato. La técnica ELISA permitió discriminar la efectividad de los procedimientos para el lavado de envases vacíos del herbicida. La LSD fue igualmente efectiva que el TLM, lo que constituye el primer antecedente relacionado a este sistema

    Estrategias de descontaminación de envases vacíos del herbicida glifosato en Entre Ríos

    Get PDF
    El glifosato es el herbicida con mayor volumen comercializado en Argentina, lo que genera gran cantidad de envases, con diferente grado de descontaminación. La empresa Spraytec posicionó la lanza Dualtec® (LSD) como método alternativo al triple lavado manual (TLM). Con la finalidad de conocer el grado de adopción de las prácticas de descontaminación de los envases vacíos de fitosanitarios y detectar residuos de glifosato en el agua de lavado mediante técnicas analíticas, se realizaron encuestas a productores agrícolas y a empresas expendedoras de fitosanitarios de Entre Ríos, bioensayos con semillas de lechuga y ensayos de efectividad de prácticas de lavado a través del Test ELISA. La mayoría de los productores agrícolas y operarios de pulverizadoras conoce el triple lavado. El grado de adopción de este último es variable, y se relaciona con el Departamento encuestado. El mayor porcentaje de productores y de empresas almacena los envases vacíos en sitios específicos. La lechuga fue altamente sensible a los cambios en las concentraciones de glifosato. La técnica ELISA permitió discriminar la efectividad de los procedimientos para el lavado de envases vacíos del herbicida. La LSD fue igualmente efectiva que el TLM, lo que constituye el primer antecedente relacionado a este sistema

    Atezolizumab Plus Bevacizumab as First-line Treatment for Patients with Metastatic Nonsquamous Non-Small Cell Lung Cancer with High Tumor Mutation Burden : A Nonrandomized Controlled Trial

    Get PDF
    Antiangiogenic drug combinations with anti-programmed cell death 1 protein and anti-programmed cell death 1 ligand 1 (PD-L1) agents are a novel treatment option for lung cancer. However, survival remains limited, and the activity of these combinations for tumors with high tumor mutation burden (TMB) is unknown. To assess the clinical benefits and safety of atezolizumab plus bevacizumab for patients with high-TMB advanced nonsquamous non-small cell lung cancer (NSCLC). This multicenter, single-arm, open-label, phase 2 nonrandomized controlled trial (Atezolizumab Plus Bevacizumab in First-Line NSCLC Patients [TELMA]) included treatment-naive patients aged 18 years or older with confirmed stage IIIB-IV nonsquamous NSCLC with TMB of 10 or more mutations/megabase and no EGFR, ALK, STK11, MDM2, or ROS1 alterations. From May 2019 through January 2021, patients were assessed at 13 sites in Spain, with follow-up until February 28, 2022. Participants were given atezolizumab, 1200 mg, plus bevacizumab, 15 mg/kg, on day 1 of each 21-day cycle. Treatment was continued until documented disease progression, unacceptable toxic effects, patient withdrawal, investigator decision, or death. Main Outcomes and Measures: The primary end point was 12-month progression-free survival (PFS) rate (according to Response Evaluation Criteria in Solid Tumours, version 1.1 criteria); PFS was defined as the time from enrollment to disease progression or death. Adverse events were monitored according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. A total of 307 patients were assessed for trial eligibility, of whom 266 were ineligible for enrollment. Of the 41 patients enrolled, 3 did not fulfill all inclusion criteria and were excluded. The remaining 38 patients (28 [73.7%] male; mean [SD] age, 63.7 [8.3] years) constituted the per-protocol population. The 12-month PFS rate was 51.3% (95% CI, 34.2%-66.0%), which met the primary end point. The 12-month overall survival (OS) rate was 72.0% (95% CI, 54.1%-83.9%). The median PFS was 13.0 months (95% CI, 7.9-18.0 months), and the median OS was not reached. Of the 38 patients, 16 (42.1%) achieved an objective response and 30 (78.9%) achieved disease control. The median time to response was 2.8 months (IQR, 2.8-3.58 months), with a median duration of response of 11.7 months (range, 3.57-22.4 months; the response was ongoing at cutoff). Of 16 responses, 8 (50.0%) were ongoing. Most adverse events were grade 1 or 2. For atezolizumab, the most common adverse events were fatigue (6 [15.8%]) and pruritus (6 [15.8%]). For bevacizumab, they were hypertension (10 [26.3%]) and proteinuria (4 [10.5%]). Drug discontinuation occurred in 2 patients receiving atezolizumab (5.3%) and 3 patients receiving bevacizumab (7.9%). PD-L1 levels were not associated with response, PFS, or OS. These findings suggest that atezolizumab with bevacizumab is a potential treatment for high-TMB nonsquamous NSCLC. ClinicalTrials.gov Identifier: NCT03836066

    Impacto de sulfentrazona, isoxaflutol e oxyfluorfem sobre a microbiota de dois solos florestais

    Get PDF
    Questões referentes à aplicação de herbicidas em pré-emergência das plantas daninhas na cultura do eucalipto merecem destaque devido ao impacto dessa prática no ambiente, principalmente sobre a atividade microbiana do solo e micro-organismos benéficos, como os fungos micorrízicos e os solubilizadores de fosfatos. Objetivou-se estudar o impacto da aplicação dos herbicidas sulfentrazona, isoxaflutol e oxyfluorfem sobre a colonização micorrízica, biomassa e atividade microbiana de dois solos florestais cultivados com eucalipto. O ensaio foi conduzido em casa de vegetação utilizando um solo argiloso e um solo francoarenoso distribuídos em vasos de 12 dm³. O esquema fatorial utilizado foi 4 x 3, sendo três herbicidas (sulfentrazona, isoxaflutol e oxyfluorfem) mais a testemunha e três avaliações (5, 20 e 70 dias após a aplicação - DAA), no delineamento inteiramente casualizado com quatro repetições. Após a aplicação dos herbicidas na dose recomendada para a cultura transplantaram-se as mudas do híbrido de Eucalyptus grandis x E. urophylla. Avaliaram-se a biomassa microbiana, a taxa respiratória do solo, o quociente metabólico e o potencial de solubilização de fosfato inorgânico aos 5, 20 e 70 DAA. Aos 70 DAA verificou-se a colonização micorrízica e a viabilidade de esporos. Os herbicidas sulfentrazona, isoxaflutol e oxyfluorfem, bem como o tempo decorrido da aplicação afetaram os indicadores microbiológicos de maneira diferenciada. No solo franco-arenoso, o sulfentrazona foi mais prejudicial à biomassa microbiana, à colonização micorrízica e aos micro-organismos solubilizadores de fosfato inorgânico. No solo argiloso, no entanto, a aplicação dos três herbicidas não afetou a biomassa microbiana, mas reduziu a colonização radicular do eucalipto por fungos micorrízicos arbusculares e o potencial de solubilização de fosfato inorgânico. O herbicida sulfentrazona se destacou por provocar aumento do número de esporos não viáveis de fungos micorrízicos arbusculares nesse solo
    corecore