► Land equivalent ratios were assessed for maize or sunflower intercropped with soybean. ► Sunflower or maize yield response to plant density influenced yield of the intercrop. ► Yield of sunflower ...and maize was reduced from sole to intercrop at each plant density. ► Yield reductions were associated with lower intra-row spacing in the intercrops.
Maize–soybean and sunflower–soybean intercrops have the potential for increasing yield per unit land area and time in fully mechanized farming systems. The objectives of this work were to measure the land equivalent ratio index of maize and sunflower intercropped to soybean, to assess the effects of plant density of its components, and to gain insight into ecophysiological processes affecting their yield determination. Maize–soybean and sunflower–soybean intercrops and their respective sole crops were grown at Balcarce, Argentina during two growing seasons. Treatments included a wide range of plant densities for sole and intercropped sunflower (2–9 plants
m
−2) and maize (4–12 plants
m
−2). Plants were harvested to determine shoot dry matter and grain yield per plot and at the individual plant level. Land equivalent ratio index (LER) increased 11% (mean of the two years) when plant density of sunflower was reduced from 6 to 3 plants
m
−2; and LER increased 5% (year 1) or it was maintained (year 2) when maize plant density was reduced from 8 to 4 plants
m
−2. Yield response to plant density of sunflower and maize influenced LER. The response to plant density of intercropped sunflower and maize grain yield followed the same pattern than that in a sole crop, and grain yield of intercropped sunflower or maize were lower than those for the sole crops at each plant density except at the lowest sunflower plant density. Yield reductions from sole crop to intercrop at each plant density averaged 20% and were associated (i) with lower intra-row spacing in the intercrop and (ii) with a lower shoot production rather than to a change in the dry matter partitioning to reproductive structures; in addition, detrimental effects of soybean over maize or sunflower yield were undetectable.
Reduced row spacing has shown to increase maize (Zea mays L.) yield; however there are conflicting results on whether narrow rows increases maize crop evapotranspiration and/or water use efficiency. ...This work analyzes the response of maize yield, crop evapotranspiration (ET) and water use efficiency to reduced row spacing under different water and N regimes. Maize crops were grown at Balcarce, Argentina, during two seasons. Treatments included two water regimes (rain-fed and irrigated), two rows spacing (35 and 70 cm) and two rates of N (i.e., 180 kg N ha-1 or nonfertilized). Soil water content was measured through the growing seasons using a neutron probe, grain yield and shoot dry matter were determined at physiological maturity. Grain yield response to narrow rows ranged from 0 to 23%; it was higher for water limited (i.e., rain-fed crops) and/or N deficient crops (i.e., nonfertilized crops) and lower for crops with high N fertilization and irrigation. Narrow rows consistently increased (8%) crop ET during the initial stages of crop growth; and N fertilization did not influence ET response to reduced row spacing during this period. Initial differences in ET between row spacing treatments were diluted as the season progressed, and seasonal crop ET was not influenced by row spacing. Reduced row spacing increased water use efficiency for grain production up to 17%; increments were larger in N deficient crops and/or with water limitations but were negligible in N fertilized and irrigated crops.
This study quantified sunflower (Helianthus annuus L.) water use efficiency for seed (WUEg) and for oil yield (WUEo) and their components (i.e., evapotranspiration ET, seed and oil yields) in ...response to plant density increments and studied, in particular, the underlying processes relevant to the responses of crop ET to plant density (i.e. water uptake pattern, intercepted photosynthetically active radiation iPAR, and soil water depletion profile). Sunflower was grown at 3, 6, and 9 plants m−2 in Season 1 and at 2, 3 and 6 plants m−2 in Season 2. Measurements included (i) soil water content and iPAR during the whole growing season, and (ii) seed and oil yield at physiological maturity. Crop ET was estimated by means of a water balance, and it was analyzed during three different periods (i.e. vegetative, critical period for seed set, and seed filling period). Increasing sunflower plant density from 2 to 9 plants m−2 did not modify seasonal ET, but it changed the water uptake pattern through the season; it increased ET during the vegetative period by depleting more water from deep soil layers (i.e., 41–140 cm), but it reduced ET during the seed‐filling period. Increments in plant density increased seed and oil yield in accordance with significant iPAR increments, whereas harvest index remained stable. Sunflower WUEg ranged from 4.8 to 9.4 kg ha−1 mm−1, WUEo ranged from 1.8 to 4.5 kg oil ha−1 mm−1 across plant densities, and they were positively and closely associated with seasonal iPAR.
Slowing the progression of Alzheimer disease (AD) might be the greatest unmet medical need of our time. Although one AD therapeutic has received a controversial accelerated approval from the FDA, ...more effective and accessible therapies are urgently needed. Consensus is growing that for meaningful disease modification in AD, therapeutic intervention must be initiated at very early (preclinical or prodromal) stages of the disease. Although the methods for such early-stage clinical trials have been developed, identification and recruitment of the required asymptomatic or minimally symptomatic study participants takes many years and requires substantial funds. As an example, in the Anti-Amyloid Treatment in Asymptomatic Alzheimer's Disease Trial (the first phase III trial to be performed in preclinical AD), 3.5 years and more than 5,900 screens were required to recruit and randomize 1,169 participants. A new clinical trials infrastructure is required to increase the efficiency of recruitment and accelerate therapeutic progress. Collaborations in North America, Europe and Asia are now addressing this need by establishing trial-ready cohorts of individuals with preclinical and prodromal AD. These collaborations are employing innovative methods to engage the target population, assess risk of brain amyloid accumulation, select participants for biomarker studies and determine eligibility for trials. In the future, these programmes could provide effective tools for pursuing the primary prevention of AD. Here, we review the lessons learned from the AD trial-ready cohorts that have been established to date, with the aim of informing ongoing and future efforts towards efficient, cost-effective trial recruitment.
In this paper the first study of the upward going events detected by the telescopes of the Extreme Energy Event (EEE) project is reported. The EEE project consists of a detector array of Multigap ...Resistive Plate Chambers located at selected sites on the Italian territory. During autumn 2014 the first coordinated data taking period took place and around one billion candidate tracks were collected. Among them, of particular interest is the sample of particles which cross the telescopes from below. The results obtained demonstrate that the EEE telescopes can distinguish the electrons produced as decay products of cosmic muons stopped in the ground, or in the last chamber of the telescopes themselves, confirming the excellent performance of the system for the investigation of intriguing cosmic phenomena.
We report about the development status of large area gaseous single photon detectors based on a novel hybrid concept for RICH applications.
The hybrid concept combines Thick Gaseous Electron ...Multipliers (THGEMs) coupled to CsI, working as a photon sensitive pre-amplification stage, and Micromegas, as a multiplication stage. The most recent achievements within the research and development programme consist in the assembly and study of 300×300mm2 hybrid photon detectors, the optimization of front-end electronics, and engineering towards large area detectors. Hybrid detectors with an active area of 300×300mm2 have been successfully operated in laboratory conditions and at a CERN PS T10 test beam, achieving effective gains in the order of 105 and good time resolution (σ=7ns); APV25 front-end chips have been coupled to the detector resulting in noise levels lower than 1000 electrons; the production and characterization of 300×600mm2 THGEMs is ongoing.
A set of hybrid detectors with 600×600mm2 active area is envisaged to upgrade COMPASS RICH-1 at CERN in 2016.
•The hybrid detector is a novel concept for large area gaseous photon detectors.•The hybrid concept combines Thick Gaseous Electron Multipliers and Micromegas.•The COMPASS RICH-1 upgrade will adopt hybrid detectors to replace the existing MWPCs
We are developing large size THick GEM (THGEM)-based detectors of single photons, mainly meant for Cherenkov imaging applications. The R&D programme includes the complete characterisation of the ...THGEM electron multipliers, the study of the aspects related to the detection of single photons and the engineering towards large size detector prototypes. Our most recent achievements include dedicated studies concerning the ion backflow to the photocathode; relevant progress in the engineering aspects, in particularly related to the production of large-size THGEMs, where the strict correlation between the local gain-value and the local thickness-value has been demonstrated and a 300300 mm super(2) active area detector has been successfully operated at the CERN PS T10 test beam; the introduction of a new hybrid detector architecture, offering promising performance, which is formed by a THGEM layer which acts both as photocathode and pre-amplification device, followed by a MICROMEGAS (MM) multiplication stage. We report about the general status of the R&D programme and, in detail, about the recent progress.
THGEM-based photon detectors for the upgrade of COMPASS RICH-1 Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
Odprti dostop
New Cherenkov photon detectors are being developed for the upgrade of COMPASS RICH-1. The detectors are based on THGEMs, arranged in a three layer architecture, with a CsI film on the first layer ...acting as a reflective photocathode. The response of THGEMs with various geometries under different conditions has been studied and photon detector prototypes have been built, tested in laboratory and operated during test beam runs providing a typical gain of 105 and a time resolution of better than 10ns. A photon detector prototype with 300×300mm2 active area, operated at the CERN PS T10 test beam in November 2012, has confirmed the validity of this novel technology and has allowed further studies of the detector response.
•The COMPASS THGEM R&D team has performed systematic studies and parameter optimization for THGEMs to be used in RICH applications.•A triple-THGEM photon detector with 300×300mm2 active area has been successfully tested at the CERN PS T10 test-beam.•A photon detector prototype based on coupling THGEM and Micromegas has provided encouraging results in laboratory tests.•For the upgrade of COMPASS RICH-1 a set of THGEM-based photon detectors will be produced.
THGEM based photon detector for Cherenkov imaging applications Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
We are developing a single photon detector for Cherenkov imaging counters. This detector is based on the use of THGEM electron multipliers in a multilayer design. The major goals of our project are ...ion feedback suppression down to a few per cent, large gain, fast response, insensitivity to magnetic fields, and a large detector size.
We report about the project status and perspectives. In particular, we present a systematic study of the THGEM response as a function of geometrical parameters, production techniques and the gas mixture composition. The first figures obtained from measuring the response of a CsI coated THGEM to single photons are presented.
The EEE (Extreme Energy Events) Project is an experiment for the detection of cosmic ray muons by means of a sparse array of telescopes, each made of three Multigap Resistive Plate Chambers (MRPC), ...distributed over all the Italian territory and at CERN. The main scientific goals of the Project are the investigation of the properties of the local muon flux, the detection of Extensive Air Showers (EAS) and the search for long-distance correlations between far telescopes. The Project is also characterized by a strong educational and outreach aspect since the telescopes are managed by teams of students and teachers who had previously constructed them at CERN. In this paper an overall description of the experiment is given, including the design, construction and performance of the telescopes. The operation of the whole array, which currently consists of more than 50 telescopes, is also presented by showing the most recent physics results.
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