672 research outputs found
Greenhouse Management for Better Vegetable Quality, Higher Nutrient Use Efficiency and Healthier Soil
Greenhouse cultivation provides an artificially controlled environment for the year-round production of vegetables, and has played an increasingly important role in agriculture production systems in recent decades. Recent works have shown that improving greenhouse conditions can promote the growth of vegetables and enhance the uptake of nutrients, leading to better vegetable quality. Meanwhile, greenhouse conditions not only directly influence soil nutrient cycling processes and properties, but also indirectly affect them by regulating vegetable root growth and plantâsoil interactions. This Special Issue features twelve original research articles that deal with the effects of novel greenhouse practices and strategies on the yield and quality of horticulture crops, as well as greenhouse soil properties. Among these publications, three studied the effects of fertilizers, including organic and macro- and micro-nutrient fertilizers, on the growth and nutrient uptake of vegetables. Two articles described the effects of water and nutrient supply using irrigation or hydroponic supplying systems on the yield and quality of vegetables. Four articles investigated the effects of environmental conditions (mainly light and temperature) on the growth and quality of vegetables. In terms of degenerated greenhouse soil, three articles showed how reductive soil disinfestation decreased soil salinity, improved soil quality, and inactivated soil-borne pathogens
Ozone depletion, greenhouse gases, and climate change
This symposium was organized to study the unusual convergence of a number of observations, both short and long term that defy an integrated explanation. Of particular importance are surface temperature observations and observations of upper atmospheric temperatures, which have declined significantly in parts of the stratosphere. There has also been a dramatic decline in ozone concentration over Antarctica that was not predicted. Significant changes in precipitation that seem to be latitude dependent have occurred. There has been a threefold increase in methane in the last 100 years; this is a problem because a source does not appear to exist for methane of the right isotopic composition to explain the increase. These and other meteorological global climate changes are examined in detail
Recent Developments in Aviation Law
Recent Developments in Aviation Law addresses developments in aviation law from January 2022 through December 2022. This submission focuses on certain cases in the area of aviation law that are expected to have a significant impact upon, and ramifications for, the industry going forward such as: (1) the Federal Aviation Act and Federal Aviation Regulations; (2) the Air Carrier Access Act; (3) the General Aviation Revitalization Act; (4) the Airline Deregulation Act; (5) the Montreal and Warsaw Conventions; (6) the Federal Tort Claims Act; and (7) the Death on the High Seas Act. Finally, this submission also discusses recent developments relating to the Federal Aviation Administrationâs regulations for unmanned aircraft, as well as the potential impact of recent developments in the application of the Feres Doctrine
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Optimization of volatile organic compound sensitivity of Vocus PTR-ToF-MS for quantifying disinfection byproducts
Recent advances in volatile organic compound (VOC) measurement techniques have led to the release of the Vocus 2R PTR-ToF, which offers real-time measurements of over 1500 compounds. The Vocus 2R PTR-ToF mass spectrometer offers world-leading sensitivity and mass resolution for the detection of VOCs in multiple ionization modes, but to maximize its capabilities it is important to adjust its operational parameters to reach the highest sensitivities for VOCs of interest. Here, a known mixture of 17 compounds was measured by the Vocus PTR-ToF at a constant flow rate as parameters of the Vocus, such as the reactor temperature, pressure, and voltage were ramped individually. Two ionization modes, HâOâș and NHââș, were used and sensitivities were optimized for each through evaluation of the ramping routine. As a case study to apply the optimized parameters, bleach and hydrogen peroxide were introduced to an environmental chamber via two methods: (a) spraying from a bottle onto a tabletop and (b) vaporizing into a mist using a humidifier within the chamber. The Vocus PTR-ToF detects compounds from many functional groups over a wide range of masses and its time resolution allows for differentiation of compounds emitted directly from the disinfectant spraying from byproducts resulting from indoor chemistry.Civil, Architectural, and Environmental Engineerin
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Is the NEM broken? Policy discontinuity and the 2017-2020 investment megacycle
The recent history of Australiaâs National Electricity Market (NEM) from 2012-2017 has been problematic with sudden coal plant closures, a tight domestic gas market and sharply rising electricity prices. The supply-side response that followed from 2017-2
Validation of the 40 Hz Auditory Steady State Response as a Pharmacodynamic Biomarker of Evoked Neural Synchrony
Schizophrenia is a troubling and severe mental illness that is only incompletely treated by currently available drugs. New drug development is hindered by a scarcity of functionally relevant pharmacodynamic biomarkers that are translatable across preclinical and human subjects. Although psychosis is a major feature of schizophrenia, cognitive and negative symptoms determine the long-term functional outcomes for patients. Stimulus-evoked neural synchrony at gamma (~ 40 Hz) frequency plays an important role in the processing and integration of sensory information. Not surprisingly, schizophrenia patients show deficits in gamma oscillations. NMDA receptor (NMDAR) activation on fast-spiking parvalbumin-positive interneurons is deemed important for the generation of gamma oscillations. NMDA hypofunction has been proposed as an alternative hypothesis to the well-known dopamine dysregulation to explain the neurochemical abnormalities associated with schizophrenia. For this dissertation, we validated a preclinical model to pharmacologically probe NMDA-mediated gamma oscillations by further characterizing the auditory-steady state response (ASSR) in female Sprague Dawley rats. The ASSR is a measure of cortical neural synchrony evoked in response to periodic auditory stimuli. ASSR at 40 Hz is consistently disrupted in patients. First, we established the reliability of click train-evoked 40 Hz ASSR and tone-evoked gamma oscillations in 6 separate sessions, spread over a 3-week period. Then we established the sensitivity of these neural synchrony measures to acute NMDAR blockade using the high affinity NMDA channel blocker MK-801, using a repeated measures design. Next, we compared the reliability and sensitivity of the 40 Hz ASSR from two distinct recording sites. Results from this study showed that as compared to vertex, temporal recording showed a greater gamma synchrony. However, the temporal recording had poor test-retest reliability and lower sensitivity to MK-801-induced disruption. Lastly, we characterized the dose-response profiles of an NMDA co-agonist D-serine, an atypical (clozapine) and a typical (haloperidol) antipsychotic, on the 40 Hz ASSR. Results from these studies showed that only clozapine was effective in robustly augmenting 40 Hz ASSR. Furthermore, only clozapine pretreatment had partial protective effect against MK-801 induced ASSR disruption. Overall, this work establishes that vertex recorded 40 Hz ASSR is a reliable neural synchrony biomarker in female SD rats that is amenable for bidirectional pharmacodynamic modulation
Review of world experience and properties of materials for encapsulation of terrestrial photovoltaic arrays
Published and unpublished information relating to encapsulation systems and materials properties was collected by searching the literature and appropriate data bases (over 1,300 documents were selected and reviewed) and by personal contacts including site and company visits. A data tabulation summarizing world experience with terrestrial photovoltaic arrays (50 installations) is presented in the report. Based on criteria of properties, processability, availability, and cost, candidate materials were identified which have potential for use in encapsulation systems for arrays with a lifetime of over 20 years high reliability, an efficiency greater than 10 percent, a total price less than $500/kW, and a production capacity of 500,000 kW/yr. The recommended materials (all commercially available) include, depending upon the device design, various borosilicate and soda-lime glasses and numerous polymerics suitable for specific encapsulation system functions
Immigration Detainers, Local Discretion, and State Law\u27s Historical Constraints
This thesis is an effort to investigate the operation and the performanceof modular multilevel converters (M2Cs). Proven to be the most promisingtopology in high-voltage high-power applications, it is necessary to put aneffort in understanding the physical laws that govern the internal dynamicsof such converters, in order to design appropriate control methods. AlthoughM2Cs belong to the well-studied family of voltage-source converters (VSCs),and claim a modular structure, their control is significantly more complicatedcompared to two- or three-level VSCs, due to the fact that a much highernumber of switches and capacitors are needed in such a topology. This thesishighlights the important parameters that should be considered when designingthe control for an M2C, through analyzing its internal dynamics, and alsosuggests ways to control such converters ensuring stable operation withoutcompromising the performance of the converter.Special focus is given on ac motor-drive applications as they are very demandingand challenging for the converter performance. Interactions betweenthe internal dynamics and the dynamics of the driven motor are experimentallyinvestigated. The problem of operating the converter when connectedto a motor standing still is visited, even under the condition that a greatamount of torque and current are requested, in order to provide an idea forthe converter requirements under such conditions. Finally, an optimization ofthe converter operation is suggested in order to avoid overrating the convertercomponents in certain operation areas that this is possible.All analytical investigations presented in this thesis are confirmed by experimentalresults on a laboratory prototype converter, which was developedfor the purposes of this project. Experimental verification proves the validityof the theoretical investigations, as well as the correct performance of thecontrol methods developed during this project on a real, physical converter,hoping that the results of this thesis will be useful for large-scale implementations,in the mega- or even giga-watt power range.Denna avhandling Ă€r ett försök att undersöka drift och egenskaper avmodulĂ€ra multinivĂ„omvandlare (M2C:er). Eftersom denna topologi anses varaden mest lovande inom högspĂ€nings-högeffekt-tillĂ€mpningar Ă€r, och somett underlag för att kunna formulera lĂ€mpliga styrmetoder, Ă€r det nödvĂ€ndigtatt lĂ€gga kraft i att försöka förstĂ„de fysikaliska lagar som styr den inredynamiken i sĂ„dana omvandlare. Ăven om M2C:erna tillhör den vĂ€lstuderadefamiljen av spĂ€nningsstyva omvandlare (VSC:er), och har en modulĂ€rstruktur, Ă€r deras reglering avsevĂ€rt mer komplicerad jĂ€mfört med tvĂ„- ellertre-nivĂ„omvandlare, eftersom ett mycket större antal switchar och kondensatorerĂ€r nödvĂ€ndiga i en sĂ„dan topologi. Denna avhandling sĂ€tter fingretpĂ„ de parametrar som mĂ„ste beaktas nĂ€r man konstruerar regleringen för enM2C, genom att analysera den interna dynamiken, samt att föreslĂ„ sĂ€tt attstyra sĂ„dana omvandlare sĂ„att stabil drift kan sĂ€kerstĂ€llas utan att negativtpĂ„verka prestanda.Ett speciellt fokus lĂ€ggs pĂ„ vĂ€xelströmsmotordrifter eftersom de Ă€r sĂ€rskiltutmanande vad gĂ€ller prestanda. VĂ€xelverkan mellan den interna dynamikenoch motorns dynamik undersöks experimentellt. Problemet att driva motornvid stillestĂ„nd behandlas Ă€ven i fallet med hög ström och högt moment för atterhĂ„lla kunskap om kraven pĂ„omvandlaren i sĂ„dana fall. Slutligen föreslĂ„s enoptimering av omvandlarens drifttillstĂ„nd för att undvika överdimensioneringav omvandlarens komponenter i de fall detta Ă€r möjligt.Alla analytiska undersökningar som lĂ€ggs fram i denna avhandling Ă€r bekrĂ€ftadegenom experimentella resultat frĂ„n en laboratorieomvandlare, somutvecklats inom ramen för detta arbete. Den experimentella verifieringen bevisargiltigheten av alla teoretiska undersökningar. Den visar ocksĂ„ pĂ„ demycket goda prestanda som de utvecklade styrmetoderna har vid drift aven verklig fysisk omvandlare. Förhoppningen Ă€r att resultaten frĂ„n detta arbetekan komma till anvĂ€nding i storskaliga implementerinar i mega- ellergiga-wattklassen.QC 20141201</p
Measurements and simulation of speciated PM2.5 in south-west Europe
Chemically speciated concentrations of PM2.5 (sulphate, ammonium, nitrate, elemental and organic carbon) were simulated in south-west Europe using the three-dimensional air quality model CAMx driven by the MM5 meteorological model. The inner domain covered the south-west region of Spain with a high spatial (2 km Ă 2 km) and temporal resolution (1 h). The simulation results were evaluated against experimental data obtained in four intensive field campaigns performed in 2008 and 2009 at urban and rural sites. PM2.5 measurements of secondary inorganic compounds and carbonaceous aerosol plus a suite of major and trace elements were determined. High time resolution (10 min) measurements of Black Carbon (BC) were also conducted. The model captured the variability in the ammonium concentrations in both summer and winter periods, although it tended to underestimate the magnitude of concentrations, while for sulphate the performance was better during the summer periods. Particulate ammonium nitrate was only simulated in significant concentrations in the wintertime campaign. This was found to be consistent with the measured composition of PM2.5 where most of nitrate (79â94%) and a significant fraction of sulphate (24â37%) were estimated to be present as non-ammonium salts. These non-ammonium nitrate salts were attributed to the formation of NaNO3. The model PM2.5 primary elemental carbon simulations, evaluated with hourly resolution, captured the diurnal and seasonal variability of PM2.5 BC concentrations at the urban site while poorer performance was observed at the rural site. A large underestimation was observed for simulated PM2.5 organic carbon concentrations during all campaigns. Scenarios of pollution events linked to emissions from south-west Spain, shipping and contributions from more distant emission sources such as Portugal were identified. These results highlight how the distinct features of PM2.5 composition in southern Europe regions, such as the large contribution of non-ammonium salts, need to be taken into account both in model evaluation and in future implementation of aerosol modelling systems.The authors gratefully acknowledge funding from the Department
of Innovation, Science and Enterprise of the Government of
Andalusia through the research projects AER-REG (P07-RNM-
03125) and SIMAND (P07-RNM-02729) and from the Department
of Environment, Andalusian Regional Government (project: 199/
2011/C/00). In addition, we thank the Spanish Ministry of Economy
and Competitiveness for funding through the project POLLINDUST
(CGL2011-26259)
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