An RF excited plasma cathode electron beam gun design

A plasma cathode electron beam (EB) gun is presented in this work. A radio frequency (RF) excited plasma at 84 MHz was used as the electron source to produce a beam power of up to 3.2 kW at -60 kV accelerating voltage. The pressure in the plasma chamber is approximately 1 mbar. The electrons are extracted from the plasma chamber to the vacuum chamber (at 10-5 mbar) through a diaphragm with a 0.5 mm diameter nozzle. Advantages over thermionic cathode guns were demonstrated empirically. Maintenance costs are reduced, as the cathode does not wear out as quickly during use. RF modulation can be used for controlling the beam power and thus there is no requirement for a grid cup electrode. Rapid (sub 1 microsecond) beam pulsing is achievable. Optical emission spectroscopy has been used to study the plasma parameters that affect the level of beam current

Characterisation of an RF excited argon plasma cathode electron beam gun

This work describes the experimental set up used for carrying out spectroscopic measurements in a plasma cathode electron beam (EB) gun. Advantages of plasma cathode guns over thermionic guns are described. The factors affecting electron beam power such as plasma pressure, excitation power and plasma chamber geometry are discussed. The maximum beam current extracted was 53 mA from a 0.5 mm diameter aperture in the plasma chamber. In this work, the electron source is an argon plasma excited at 84 MHz. The pressure in the plasma chamber was measured to be within 0.9 to 1.2 mbar and was controlled by varying gas flow rates. The vacuum chamber was at a pressure of 10^-5 mbar.TWI and Brunel University

Biological Fixation of N2 in Mono and Polyspecific Legume Pasture in the Humid Mediterranean Zone of Chile

del Pozo, A (del Pozo, Alejandro). Univ Talca, Fac Ciencias Agr, Talca, ChileDespite annual legume pasture are of great importance for dryland agricultural systems in Mediterranean environments, there are few studies of N-2 biological fixation (NBF) reported in Chile. In this study the NBF of four annual legume species: subterranean clover (Trifolium subterraneum L.), yellow serradella (Ornithopus compressus L.), arrow-leaf clover (T. vesiculosum L.), and crimson clover (T. incarnatum L.) (Experiment 1), as well as seven mixtures of these species (Experiment 2) were assessed. The NBF was measured by the N-15 natural abundance technique. The objective was to determine NBF in the legume species and in distinct mixtures used. The study was carried out in an Andisol of the Andean Precordillera located in the humid Mediterranean zone of Chile. Pasture was evaluated for biomass; and total N and natural abundance of N-15 were analyzed in plant material samples. In Experiment 1 (monospecific legume species pasture), N derived from fixation ranged between 43 and 147 kg N ha(-1) and where T. vesiculosum and T. subterraneum presented statistical differences (P <= 0.05) in connection with the other species. In the legume mixtures (Experiment 2), N derived by fixation varied between 97 and 214 kg N ha(-1) where the 50-50 mixtures (T. subterraneum and O. compressus, or T. subterraneum and T. vesiculosum, respectively) had the highest N fixation. Fixed N ranged between 12 and 25 kg N t(-1) DM, showing significant differences among mono and polyspecific legume species

The Effect of Nitrogen Fertilisation on the Morphological Development and Growth Rate of Star Grass (\u3cem\u3eCynodon nlemfuensis\u3c/em\u3e)

Nitrogen is one of the main inputs used in forage production systems to increase productivity. However, in Cuba, the availability of fertiliser N is limited and therefore if applied, needs to be used with high efficiency. Previous studies (Johnson, 2001, Del Pozo, 2003) investigated the effects of N on growth, carbohydrate and protein content but did not consider morphological changes in Cynodon nlemfuensis. A study was therefore undertaken investigating how N application influences morphological development of the plant and how these changes might affect the efficiency of use of applied N

Topological Measure Locating the Effective Crossover between Segregation and Integration in a Modular Network

We introduce an easily computable topological measure which locates the effective crossover between segregation and integration in a modular network. Segregation corresponds to the degree of network modularity, while integration is expressed in terms of the algebraic connectivity of an associated hyper-graph. The rigorous treatment of the simplified case of cliques of equal size that are gradually rewired until they become completely merged, allows us to show that this topological crossover can be made to coincide with a dynamical crossover from cluster to global synchronization of a system of coupled phase oscillators. The dynamical crossover is signaled by a peak in the product of the measures of intra-cluster and global synchronization, which we propose as a dynamical measure of complexity. This quantity is much easier to compute than the entropy (of the average frequencies of the oscillators), and displays a behavior which closely mimics that of the dynamical complexity index based on the latter. The proposed toplogical measure simultaneously provides information on the dynamical behavior, sheds light on the interplay between modularity vs total integration and shows how this affects the capability of the network to perform both local and distributed dynamical tasks

Colaboración Universidad/Administración: Sesión PBL (Practic Based Learning) para la notificación de preparados cosméticos y dermofarmacéuticos al CPNP (Cosmetic Products Notification Portal) para estudiantes del máster de Demofarmácia y Cosmetología (título propio de la universidad de Barcelona)

Podeu consultar la Vuitena trobada de professorat de Ciències de la Salut completa a: http://hdl.handle.net/2445/66524La notificación de toda nueva formulación cosmética al CPNP es obligatoria para poder proceder a su producción y posterior comercialización a nivel europeo. Dicha notificación es informática e implica cumplimentar una información completa acerca de ingredientes, formulación, aspectos legales, etc. en base a las especificaciones legales fijads por el Reglamento Europeo de productos cosméticos (CE1223/2009, DOUE nº342, de 22/12). El acceso a dicho portal implica el registro de la empresa productora del cosmético. Por ello y afin de que los estudiantes de tercer ciclo puedan practicar simulaciones de comunicación al CPNP, guiadas y comentadas por parte de tutores expertos, cuestión que les resultará de gran utilidad en el dia a dia de la actividad profesional para la que se están formando, se propuso al Area Funcional de Sanidad de la Subdelegación del Gobierno en Cataluña, la consecución de un acceso como empresa de elaboración de cosméticos simulada, a nombre de Facultad de Farmacia de la Universidad de Barcelona para el acceso a dicho aplicativo. Ello ha permitido la realización de una sesión práctica en la que se siguen paso a paso las diferentes etapas de la notificación para un ejemplo propuesto por el profesor, y ha permitido la práctica individualizada por parte de los 18 alumnos de la actual promoción del Máster de diferentes casos reales, lo que sirve de “reválida” de los conocimientos adquiridos en las diferentes áreas formativas, cuyo fin es el de capacitar a dichos estudiantes para poder realizar la totalidad de las etapas de I+D de un cosmético, que obviamente concluyen con la comunicación del mismo al CPNP. Este es asimismo el objetivo que se les plantea para la realización y valoración de sus correspondientes proyectos finales

Death, dying and informatics: misrepresenting religion on MedLine

BACKGROUND: The globalization of medical science carries for doctors worldwide a correlative duty to deepen their understanding of patients' cultural contexts and religious backgrounds, in order to satisfy each as a unique individual. To become better informed, practitioners may turn to MedLine, but it is unclear whether the information found there is an accurate representation of culture and religion. To test MedLine's representation of this field, we chose the topic of death and dying in the three major monotheistic religions. METHODS: We searched MedLine using PubMed in order to retrieve and thematically analyze full-length scholarly journal papers or case reports dealing with religious traditions and end-of-life care. Our search consisted of a string of words that included the most common denominations of the three religions, the standard heading terms used by the National Reference Center for Bioethics Literature (NRCBL), and the Medical Subject Headings (MeSH) used by the National Library of Medicine. Eligible articles were limited to English-language papers with an abstract. RESULTS: We found that while a bibliographic search in MedLine on this topic produced instant results and some valuable literature, the aggregate reflected a selection bias. American writers were over-represented given the global prevalence of these religious traditions. Denominationally affiliated authors predominated in representing the Christian traditions. The Islamic tradition was under-represented. CONCLUSION: MedLine's capability to identify the most current, reliable and accurate information about purely scientific topics should not be assumed to be the same case when considering the interface of religion, culture and end-of-life care

Investigation of RF and DC plasma electron sources for material processing applications

This work presents the design, development and experimental results obtained from an RF plasma cathode Electron Beam (EB) gun for material processing applications. EB currents of up to 38 mA at –60 kV were extracted and correlated to Optical Emission Spectroscopy (OES) measurements. OES measurements and Argon II ratios were used to compare hollow and flat electrode designs as well as to examine changes in other key plasma parameters (i.e. plasma pressure and excitation power). The spectroscopic measurements and Argon II ratios indicated a higher ionization rate for the hollow electrode geometries and plasma parameters that generated larger EB currents (i.e. higher excitation power and lower pressure). The RF plasma cathode gun was compared to a DC plasma cathode gun. The DC plasma cathode produced larger currents than the RF plasma chamber. This result agreed with the OES measurements, which showed a higher ionisation in the DC plasma