A note on the π-complemented algebras

π-complemented algebras are defined as those (not necessarily associative or unital) algebras such that each annihilator ideal is complemented by other annihilator ideal. Let BA denote the set of all idempotents of the extended centroid of a semiprime algebra A. We prove that if there is a maximal ideal P of BA such that PA ⊆ A then A and PA are two π-complemented algebras. As a consequence, we give a characterization of the π-complementation of the unitisation, and the multiplication ideal, of a semiprime algebra

On-chip terahertz characterisation of liquids

Spectroscopy at terahertz frequencies can be used in a wide range of applications including radio-astronomy, pharmaceutical manufacturing control, and the study of processes in molecular biology. Biomolecular samples should preferably be studied in their native environment, water, however, water poses extreme attenuation for THz-frequency waves, deteriorating or even impeding analysis using these waves. The most common THz spectroscopy method, time-domain spectroscopy, can measure water samples using free-space measurements, lacks sensitivity when trying to measure on a chip environment. To exploit the advantages that chip measurements offer, such as integration and cost, this thesis works on developing on-chip THz spectroscopy of aqueous samples using a frequency-domain approach, with vector network analysers. Vector network analysers exhibit a higher dynamic range than time-domain spectroscopy systems, making them a promising alternative for sensitive THz measurements. For maximising the sensitivity of the measurements, the losses must be minimised. One important source of losses at THz frequencies are conductor and radiation loss. In this thesis, two planar waveguides were designed, coplanar waveguide and planar Goubau line, minimising their losses at THz frequencies by avoiding the coupling to other parasitic modes, obtaining attenuation constants as low as 0.85 Np/mm for coplanar waveguide and 0.33 Np/mm for planar Goubau line. Additionally, planar Goubau line calibration structures were developed for setting the measurement plane along this planar waveguide. Finally, coplanar waveguides were integrated with microfluidic channels to perform spectroscopy measurements of water samples, showing good performances as THz sensors of high-loss liquids.This thesis is a first step towards a sensitive and miniaturised system for measuring the electrical properties of high-loss liquids, which could shed light on the fundamental biomolecular processes in the picosecond time-scale

Acercamiento a la producción más limpia como estrategia de gestión ambiental

In this paper a reflection on Cleaner Production as environmental management strategy and the advantages of it over the traditional approach of treatment at the end of the pro-cess. These advantages are mainly related to preventing pollu-tion rather than treat it to avoid its effect preventive approach. Some results of the implementation of this strategy in Cuba are relate

Planar-Goubau-line components for terahertz applications

Terahertz-wave technology has a broad range of applications, including radio astronomy, telecommunications, security, medical applications, pharmaceutical quality control, and biological sensing. However, the sources, detectors, and components are less efficient at this frequency band due to parasitic effects and increased total losses, which hinder the performance of terahertz systems. A common platform for terahertz systems is planar technology, which offers good integration, ease of fabrication, and low cost. However, it also suffers from high losses, which must be minimised to keep the system\u27s performance. A pivotal choice to reduce losses is using power-efficient waveguides, and single-conductor waveguides have shown promisingly high power efficiencies compared to multi-conductor planar waveguides. The planar Goubau line (PGL) is a planar single-conductor waveguide consisting of a metal strip on top of a dielectric substrate which propagates a quasi-transverse magnetic surface wave, similarly to Sommerfeld\u27s wire and the Goubau line, a conducting wire coated with a dielectric layer. Some limitations of the PGL, which complicate the design of components, are the lack of a ground plane and the weak dependence of impedance with the metal strip width of the line.This thesis presents the development of PGL technology and components for terahertz frequencies. It developed design strategies to maximise the power efficiency, using electrically-thin substrates, which drastically drop radiation losses compared to thick substrates. The first PGL calibration standards were developed, which de-embeds the transition needed to excite the propagation mode and sets the calibration plane along the line, allowing the direct characterisation of PGL components. This work also presents several PGL components with a straightforward design procedure, including a stopband filter based on capacitively-coupled λ/2 resonators, an impedance-matched load based on an exponentially-tapered corrugated line, and a power divider based on capacitive-gap coupled lines to a standing wave in the input port. Finally, the PGL was integrated with a microfluidic channel to measure changes in the complex refractive index of a high-loss aqueous sample (water/isopropyl alcohol) as the first step toward a biological sensor

Hydrodynamic changes in Guadalquivir estuary (Spain) due to a hypothetical tidal marsh restoration project

Tidal marsh restoration will be an important management issue in Guadalquivir Estuary in the near future. The Guadalquivir Estuary has been anthropologically modified several times, the river is bounded by embankments to protect rice and cotton plantations from tidal inundation, the meanders have been transformed into straight sections, about 80 % of the original marsh surface has been lost and approximately one-fourth of the total surface of the estuary is now part of two protected areas, one of them is a UNESCO, MAB Biosphere Reserve. A hypothetical restoration of tidal marshes will benefits different species and functions based on location, elevation, adjacent habitats, degree of hydrodynamic connectivity and would reduce the present high levels of turbidity. The restoration projects should be accompanied by studies for a better understanding of the environmental changes expected. A Large-scale construction of tidal marsh will change tidal dynamics, modify the tidal inundation regime and the freshwater flow over the surrounding areas. A hydrodynamic model has been developed to study changes in the tidal propagation and the flow regime due to a hypothetical marsh restoration. The model has been calibrated and the output has been validated with in situ water elevation and good agreement between modelled and real measurements have been obtained. A sensitivity test changing the size, locations from the estuary mouth and depth has been carried out to highlights impacts over the tidal propagation, flow regime, salinity intrusion and the tidal inundation regime. Our preliminary results show that the tidal elevation and the current speed will be considerably affected in the estuary. The model open the possibility to study interactions among the tidal marsh restoration project, Seville port operations, fisheries and agricultural activities. The numerical model will be a powerful tool in restoration projects in a complex socio-ecological system.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Autoridad Portuaria de Sevill

The temperature gradient of cereals as an optimization parameter of the milling process in hammermills

The wear degree of knives in hammermills strongly influences electricity consumption, productivity, and total operating costs. Currently, the timely replacement of the knives set is decided based on visual inspections, a feedstock load or a lifespan defined, the electric demand of the mill as compared to the limit of the motor driving it, or the vibrations of the hammermill. These approaches present different shortcomings. This study proposes the temperature gradient of the feedstock during the milling process as an indicator to monitor the wear degree of knives. The temperature gradient was implemented in a hammermill milling maize to compare two operating modes. In the conventional operating mode, the knives set mills with one edge during its lifespan, replacing the set once the electricity demand approaches the limit capacity of the electric motor driving the mill, or until the vibrations increase over safety limits. Moreover, in the proposed operating mode the temperature gradient is used to define the timely replacement/rotation of the knives edge. In this case, the four edges of the knives are used. The electricity consumption, productivity, and temperature gradient of the process were measured during the milling of ten maize loads of 2500 tons each. These data were used to characterize the performance of the hammermill, and the influence of the temperature gradient on its operational performance. As a result, a temperature gradient of 6.5 °C was defined as the optimal value to change the rotational direction or replacing the knives set in the hammermill assessed. As compared to the traditional operation approach, the use of the temperature gradient resulted in a reduction of the electricity consumption of 32%, and the greenhouse gas emissions by 37%, while reducing the total costs by 33%, and increasing productivity by 20%. Therefore, this approach stands as a significant opportunity to upgrade the operation of hammermills

Colonization dynamics of arbuscular mycorrhizal fungi (AMF) in Ilex paraguariensis crops: Seasonality and influence of management practices

The yerba mate (Ilex paraguariensis St. Hill.) is a native species from subtropical regions of Argentina, Brazil, Paraguay and Uruguay. Arbuscular mycorrhizal fungi (AMF) are symbiotically associated with 82% of the vegetable species including crops of economic importance. The aim of the present study was to determine the association of yerba mate with AMF growing in natural and crop conditions, and to evaluate the influence of tillage practices and seasonality on root colonization. We selected five situations ranging from old systems to recent implementations with different agricultural managements and intensity of tillage, as reference native trees were analyzed. Root samples of yerba mate were extracted in winter and summer during the years 2013–2014. The percentage of root colonization was determined. Significantly higher values of colonization were found in native trees. Regarding seasonality, significantly higher values on the total mycorrhizal colonization were observed in winter. Organic matter and nitrogen were the soil factors that showed significant correlation with the percentage of colonization. This work confirms the association of I. paraguariensis with AMF, showing that yerba mate is a host species under both crop and natural conditions. Even though crop management of yerba mate is compatible with the symbiosis, it affects the colonization negatively.Fil: Velázquez, María Silvana. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Juan Carlos, Fabisik. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Abarca, Camila Lucía. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Allegrucci, Natalia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cabello, Marta Noemí. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentin

Model Based Development of Quality-Aware Software Services

Modelling languages and development frameworks give support for functional and structural description of software architectures. But quality-aware applications require languages which allow expressing QoS as a first-class concept during architecture design and service composition, and to extend existing tools and infrastructures adding support for modelling, evaluating, managing and monitoring QoS aspects. In addition to its functional behaviour and internal structure, the developer of each service must consider the fulfilment of its quality requirements. If the service is flexible, the output quality depends both on input quality and available resources (e.g., amounts of CPU execution time and memory). From the software engineering point of view, modelling of quality-aware requirements and architectures require modelling support for the description of quality concepts, support for the analysis of quality properties (e.g. model checking and consistencies of quality constraints, assembly of quality), tool support for the transition from quality requirements to quality-aware architectures, and from quality-aware architecture to service run-time infrastructures. Quality management in run-time service infrastructures must give support for handling quality concepts dynamically. QoS-aware modeling frameworks and QoS-aware runtime management infrastructures require a common evolution to get their integration