290 research outputs found

    Induced Crystallization of Polyelectrolyte-Surfactant Complexes at the Gas-Water Interface

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    Synchrotron-X-ray and surface tension studies of a strong polyelectrolyte (PE) in the semi-dilute regime (~ 0.1M monomer-charges) with varying surfactant concentrations show that minute surfactant concentrations induce the formation of a PE-surfactant complex at the gas/solution interface. X-ray reflectivity and grazing angle X-ray diffraction (GIXD) provide detailed information of the top most layer, where it is found that the surfactant forms a two-dimensional liquid-like monolayer, with a noticeable disruption of the structure of water at the interface. With the addition of salt (NaCl) columnar-crystals with distorted-hexagonal symmetry are formed.Comment: 4 pages, 5 eps figure

    Beyond convergence rates: Exact recovery with Tikhonov regularization with sparsity constraints

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    The Tikhonov regularization of linear ill-posed problems with an 1\ell^1 penalty is considered. We recall results for linear convergence rates and results on exact recovery of the support. Moreover, we derive conditions for exact support recovery which are especially applicable in the case of ill-posed problems, where other conditions, e.g. based on the so-called coherence or the restricted isometry property are usually not applicable. The obtained results also show that the regularized solutions do not only converge in the 1\ell^1-norm but also in the vector space 0\ell^0 (when considered as the strict inductive limit of the spaces Rn\R^n as nn tends to infinity). Additionally, the relations between different conditions for exact support recovery and linear convergence rates are investigated. With an imaging example from digital holography the applicability of the obtained results is illustrated, i.e. that one may check a priori if the experimental setup guarantees exact recovery with Tikhonov regularization with sparsity constraints

    A Guide to Localized Frames and Applications to Galerkin-like Representations of Operators

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    This chapter offers a detailed survey on intrinsically localized frames and the corresponding matrix representation of operators. We re-investigate the properties of localized frames and the associated Banach spaces in full detail. We investigate the representation of operators using localized frames in a Galerkin-type scheme. We show how the boundedness and the invertibility of matrices and operators are linked and give some sufficient and necessary conditions for the boundedness of operators between the associated Banach spaces.Comment: 32 page

    Technical report: Modeling nitrate leaching risk from specialty crop fields during on-farm managed floodwater recharge in the Kings Groundwater Basin and the potential for its management

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    This project has focused on better understanding the potential impact of On-Farm Flood Capture and Recharge (OFFCR) on groundwater quality pertaining to salts and nitrate and on assessing potential management opportunities. To achieve these goals, we used a combination of field and modeling studies. For the field study, soil cores were taken to a depth of 30 feet in replicate across fields with three different specialty crops identified as important to the San Joaquin Valley (tomatoes, almonds, vineyards) and with potential suitability for OFFCR. A prime goal of the field study was to provide data for parameterizing two models developed to assess nitrate, salt and water transport through the vadose zone, prior to percolating into the groundwater aquifer. However, the field study also resulted in key findings that show its value as a stand-alone study: 1) Nitrate concentrations are highest in the upper vadose zone and affected by texture. Those effects are not evident in the deeper vadose zone. 2) Vadose zone nitrate concentrations are affected by the crop grown. These results suggest an opportunity for lower legacy mass transport for grapes and higher legacy mass transport for both tomatoes and almonds. 3) Variability in individual farmers’ past and present fertilizer and water management practices contributes to different legacy salt and nitrate loads in the vadose zone. Data from the field study and other related and concurrent OFFCR field efforts were used during model development. The overall modeling approach was designed to model nitrate and salt transport for lands under OFFCR operation for different crop types, vadose zone characteristics and groundwater characteristics. The defined goals of this design and modeling approach were to: 1) model nitrate and salt movement through the vadose zone and into groundwater; 2) test the model against scenarios that consider different recharge rates, cultural practices, soil types, and depths to groundwater, assessing the timing and magnitude of loading through the vadose zone and the effects on underlying groundwater; and 3) recommend management practices to mitigate potential groundwater impacts. To achieve these goals, two models were integrated to simulate nitrate and salt transport through the vadose zone to groundwater under different scenarios: a 1D Hydrus model and an analytical groundwater model (AGM)

    IMPACTO DA OFERTA DE POLEIROS SOBRE O BEM-ESTAR DE FRANGOS DE CORTE

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    Industrial broiler production presents important challenges to the welfare of the birds. The objective of this work was to increase broiler welfare through the inclusion of perches and the evaluation of their impact on the welfare of the animals. Three hundred and sixty male birds were raised from day 1to 42 in two treatments, with six boxes per treatment and 30 birds per box, being T1 – boxes with no perch and T2 – boxes with three perches each. Behavioural observations were organized as instantaneous scan sampling. Forty dayold birds were subjected to physical clinical exam to register chest feather condition and leg health. Rationconsumption, weight gain, slaughter weight and feed conversion were monitored. The frequency of perching events was higher as birds grew older, being 0.3%, 2.6% e 5.1% for the fourth, fifth and sixth weeks, respectively. During the last two weeks of life, frequency of floor pecking events was higher and of agonistic interactions was lower for broilers maintained with perches (P0.05). In the experimental conditions, we conclude that the presence of perches results in improvements of the Behavioural Freedom for the last third of the bird’s life. More research is needed regardingthe perch effects on broiler’s Sanitary Freedom. Results suggest improvement of broiler welfare due to the presence of perches.A produção industrial de frangos de corte desafia de maneira importante o bem-estar das aves. O objetivo deste foi melhorar o grau de bem-estar de frangos de corte, através do fornecimento de poleiros e da avaliação de seu impacto no bem-estar dos animais. Foram utilizados 360 frangos de corte, machos, criadosde 1 a 42 dias de idade, em dois tratamentos com seis repetições de 30 aves cada, sendo T1 sem poleiros e T2 com três poleiros por box. Foram realizadas observações das atividades comportamentais por registro instantâneo do tipo varredura. Exames físicos para condição das penas do peito e distúrbios naspernas foram realizados aos 40 dias de idade. Foram avaliados: consumo de ração, ganho de peso, peso ao abate e conversão alimentar. Foi observada freqüência de empoleiramento crescente com a idade das aves, de 0,3%, 2,6% e 5,1% na quarta, quinta e sexta semanas de idade, respectivamente. Durante as duas últimas semanas de vida, as ocorrências de ciscar foram mais freqüentes e os eventos de comportamento agonista foram menos freqüentes no tratamento com poleiros (P0,05). Conclui-se que, nas condições deste experimento, a oferta de poleiros resulta em melhoria da Liberdade Comportamental no terço final de vida das aves. O efeito dos poleiros sobre a Liberdade Sanitária deve serestudado mais detalhadamente. Os resultados sugeremmelhoria do grau de bem-estar de frangos de corte devido à oferta de poleiros

    Managed Aquifer Recharge as a Tool to Enhance Sustainable Groundwater Management in California

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    A growing population and an increased demand for water resources have resulted in a global trend of groundwater depletion. Arid and semi-arid climates are particularly susceptible, often relying on groundwater to support large population centers or irrigated agriculture in the absence of sufficient surface water resources. In an effort to increase the security of groundwater resources, managed aquifer recharge (MAR) programs have been developed and implemented globally. MAR is the approach of intentionally harvesting and infiltrating water to recharge depleted aquifer storage. California is a prime example of this growing problem, with three cities that have over a million residents and an agricultural industry that was valued at 47 billion dollars in 2015. The present-day groundwater overdraft of over 100 km3 (since 1962) indicates a clear disparity between surface water supply and water demand within the state. In the face of groundwater overdraft and the anticipated effects of climate change, many new MAR projects are being constructed or investigated throughout California, adding to those that have existed for decades. Some common MAR types utilized in California include injection wells, infiltration basins (also known as spreading basins, percolation basins, or recharge basins), and low-impact development. An emerging MAR type that is actively being investigated is the winter flooding of agricultural fields using existing irrigation infrastructure and excess surface water resources, known as agricultural MAR. California therefore provides an excellent case study to look at the historical use and performance of MAR, ongoing and emerging challenges, novel MAR applications, and the potential for expansion of MAR. Effective MAR projects are an essential tool for increasing groundwater security, both in California and on a global scale. This chapter aims to provide an overview of the most common MAR types and applications within the State of California and neighboring semi-arid regions

    The Effective Fragment Molecular Orbital Method for Fragments Connected by Covalent Bonds

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    We extend the effective fragment molecular orbital method (EFMO) into treating fragments connected by covalent bonds. The accuracy of EFMO is compared to FMO and conventional ab initio electronic structure methods for polypeptides including proteins. Errors in energy for RHF and MP2 are within 2 kcal/mol for neutral polypeptides and 6 kcal/mol for charged polypeptides similar to FMO but obtained two to five times faster. For proteins, the errors are also within a few kcal/mol of the FMO results. We developed both the RHF and MP2 gradient for EFMO. Compared to ab initio, the EFMO optimized structures had an RMSD of 0.40 and 0.44 {\AA} for RHF and MP2, respectively.Comment: Revised manuscrip

    Head of State of Exception

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    During the escalation of the “German Autumn” in 1977 the Federal German government resorted to a specific form of crisis management that had been described as an undeclared state of exception. It was Federal chancellor Helmut Schmidt in the first place who oversaw the anti-terrorist measures in the situation room where the executive branch ruled for six weeks beyond any parliamentary control. This article examines the role that Helmut Schmidt had played for the creation of a “subjective state of exception” (Julius Hatschek) and how this could be seen as stemming from Schmidt’s earlier experiences and handling of crisis situations dating back to the 1960s. In this regard it has to be asked with Giorgio Agamben, if in the West German case, the state of exception had become the rule

    Advanced Preparation Makes Research in Emergencies and Isolation Care Possible: The Case of Novel Coronavirus Disease (COVID-19)

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    The optimal time to initiate research on emergencies is before they occur. However, timely initiation of high-quality research may launch during an emergency under the right conditions. These include an appropriate context, clarity in scientific aims, preexisting resources, strong operational and research structures that are facile, and good governance. Here, Nebraskan rapid research efforts early during the 2020 coronavirus disease pandemic, while participating in the first use of U.S. federal quarantine in 50 years, are described from these aspects, as the global experience with this severe emerging infection grew apace. The experience has lessons in purpose, structure, function, and performance of research in any emergency, when facing any threat
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