Electrostatic solitary waves in the presence of excess superthermal electrons: modulational instability and envelope soliton modes

The nonlinear dynamics of electrostatic solitary waves in the form of localized modulated wavepackets is investigated from first principles. Electron-acoustic (EA) excitations are considered in a two-electron plasma, via a fluid formulation. The plasma, assumed to be collisionless and uniform (unmagnetized), is composed of two types of electrons (inertial cold electrons and inertialess kappa-distributed superthermal electrons) and stationary ions. By making use of a multiscale perturbation technique, a nonlinear Schrodinger equation is derived for the modulated envelope, relying on which the occurrence of modulational instability (MI) is investigated in detail. Stationary profile localized EA excitations may exist, in the form of bright solitons (envelope pulses) or dark envelopes (voids). The presence of superthermal electrons modifies the conditions for MI to occur, as well as the associated threshold and growth rate. The concentration of superthermal electrons (i.e., the deviation from a Maxwellian electron distribution) may control or even suppress MI. Furthermore, superthermality affects the characteristics of solitary envelope structures, both qualitatively (supporting one or the other type, for different.) and quantitatively, changing their characteristics (width, amplitude). The stability of bright and dark-type nonlinear structures is confirmed by numerical simulations.

Selectivity control in hydrogenation reactions by nanoconfinement of polymetallic nanoparticles in mesoporous thin films

A one-pot sol-gel synthesis method has been developed for the incorporation of metal nanoparticles into mesoporous oxide thin films deposited on various plane substrates by spin-coating and on the inner surface of fused silica capillaries by dip-coating. The size, the metal loading and the stoichiometry of the metal nanoparticles could be precisely controlled by following this methodology. In the first step, polymer stabilized Pt50Sn50 and Pt90Sn10 nanoparticles were obtained by a solvent-reduction method. Then, the nanoparticles were added to a metal oxide precursor sol, which was destabilized by solvent evaporation. After calcination, the obtained materials were tested in the hydrogenation of citral in both batch and continuous modes. The highest selectivity of 30% towards the unsaturated alcohols was obtained over supported Pt90Sn10 nanoparticles with a preferential formation of the cis-isomer (nerol) due to a unique confinement of the bimetallic nanoparticles in the mesoporous framework. The selectivity towards the unsaturated alcohols was further improved to 56% over the PtRu5Sn nanoparticles supported by impregnation onto mesoporous silica films. (C) 2009 Elsevier B.V. All rights reserved.

DACA: architecture to implement dynamic access control mechanisms on business tier components

Access control is a software engineering challenge in database applications. Currently, there is no satisfactory solution to dynamically implement evolving fine-grained access control mechanisms (FGACM) on business tiers of relational database applications. To tackle this access control gap, we propose an architecture, herein referred to as Dynamic Access Control Architecture (DACA). DACA allows FGACM to be dynamically built and updated at runtime in accordance with the established fine-grained access control policies (FGACP). DACA explores and makes use of Call Level Interfaces (CLI) features to implement FGACM on business tiers. Among the features, we emphasize their performance and their multiple access modes to data residing on relational databases. The different access modes of CLI are wrapped by typed objects driven by FGACM, which are built and updated at runtime. Programmers prescind of traditional access modes of CLI and start using the ones dynamically implemented and updated. DACA comprises three main components: Policy Server (repository of metadata for FGACM), Dynamic Access Control Component (DACC) (business tier component responsible for implementing FGACM) and Policy Manager (broker between DACC and Policy Server). Unlike current approaches, DACA is not dependent on any particular access control model or on any access control policy, this way promoting its applicability to a wide range of different situations. In order to validate DACA, a solution based on Java, Java Database Connectivity (JDBC) and SQL Server was devised and implemented. Two evaluations were carried out. The first one evaluates DACA capability to implement and update FGACM dynamically, at runtime, and, the second one assesses DACA performance against a standard use of JDBC without any FGACM. The collected results show that DACA is an effective approach for implementing evolving FGACM on business tiers based on Call Level Interfaces, in this case JDBC.

Exploiting non-Markovianity for quantum control

Quantum technology, exploiting entanglement and the wave nature of matter, relies on the ability to accurately control quantum systems. Quantum control is often compromised by the interaction of the system with its environment since this causes loss of amplitude and phase. However, when the dynamics of the open quantum system is non-Markovian, amplitude and phase flow not only from the system into the environment but also back. Interaction with the environment is then not necessarily detrimental. We show that the back-flow of amplitude and phase can be exploited to carry out quantum control tasks that could not be realized if the system was isolated. The control is facilitated by a few strongly coupled, sufficiently isolated environmental modes. Our paradigmatic example considers a weakly anharmonic ladder with resonant amplitude control only, restricting realizable operations to SO(N). The coupling to the environment, when harnessed with optimization techniques, allows for full SU(N) controllability.

Autoritarismo subnacional: estrategias territoriales de control político en regímenes democráticos

Este documento explora las dinámicas de cambio y continuidad de los autoritarismos subnacionales (específicamente en las provincias) en los regímenes democráticos nacionales. Tomando contribuciones de teorías propias de la política territorial provee un marco para el análisis del contexto estratégico en el que élites autoritarias en el poder y sus oponentes locales y nacionales adelantan estrategias de control territorial y de oposición. El autoritarismo subnacional no debe ser entendido como un asunto local, sino como un resultado de dinámicas más amplias de gobernanza territorial nacional en regímenes democráticos. Los conflictos entre los autoritarismos y la oposición ocurren a través de múltiples ámbitos territoriales dentro del sistema político nacional. En regímenes democráticos nacionales las élites autoritarias adelantarán tres tipos de estrategias: la parroquialización del poder, la nacionalización de su influencia, y la monopolización de los vínculos institucionales entre lo nacional y lo subnacional. La democratización subnacional, cuando ocurra, resultará entonces de la intervención por parte de actores en espacios políticas nacionales. Para este fin se han hecho dos distinciones entre las “modalidades” de cambio político subnacional: las transiciones “lideradas por partidos políticos” y las transiciones “lideradas por el centro”.-----This document examines the dynamics established between change and continuity under sub-national authoritarianisms (more specifically in provinces) in national democratic regimes. Contributions taken from local theories on territorial politics constitute the framework for our analysis of the strategic context in the midst of which authoritarian elites in power, and their local and national opponents, put forward their territorial control and opposition strategies. Still, sub-national authoritarianism must not be considered a mere local issue, but rather the final result of wider national territorial governing dynamics within democratic regimes. That is, conflicts arising between different authoritarianisms and the opposition take place in myriad territorial arenas within an established national political system. In national democratic regimes, authoritarian elites will attempt three different types of strategies: establishing a parochial-style mode of exerting power, extending its influence nationwide, and monopolizing the extant institutional links between the national and sub-national spheres. Thus, the democratization of the sub-national realm, if and when it happens, will only take place via the intervention of actors and agents from national political arenas. In order to better understand this phenomenon, two main distinctions are made between two types or modes of sub-national political change: those transitions “led by political parties” and those “led by the center”.

Desarrollo de un estado de la cuestión acerca de las interacciones entre el control de gestión y el aprendizaje organizacional.

Las organizaciones en la actualidad deben encontrar diferentes maneras de sobrevivir en un tiempo de rápida transformación. Uno de los mecanismos usados por las empresas para adaptarse a los cambios organizacionales son los sistemas de control de gestión, que a su vez permiten a las organizaciones hacer un seguimiento a sus procesos, para que la adaptabilidad sea efectiva. Otra variable importante para la adaptación es el aprendizaje organizacional siendo el proceso mediante el cual las organizaciones se adaptan a los cambios del entorno, tanto interno como externo de la compañía. Dado lo anterior, este proyecto se basa en la extracción de documentación soporte valido, que permita explorar las interacciones entre estos dos campos, los sistemas de control de gestión y el aprendizaje organizacional, además, analizar el impacto de estas interacciones en la perdurabilidad organizacional. ​

El surgimiento de las organizaciones estatales de control ambiental en el Ecuador (1930‐1960)

Este trabajo pretende documentar los cambios en la organización y las políticas estatales respecto al ambiente a mediados del siglo XX. Para ello nos hemos concentrado en la revisión de los informes ministeriales entre 1925 y 1960, que es la época en que nacen silenciosamente las organizaciones e instituciones ambientales antes de la eclosión pública de discursos y preocupaciones ecológicas entre los años 1960 y 1990. En efecto, en 1959 se creó el Parque Nacional Galápagos, con la decisiva influencia de científicos naturalistas del mundo. Puede considerarse ese año como el inicio de una nueva etapa que incluirá la aprobación de la Ley de Prevención de la Contaminación (1976), el nacimiento de Fundación Natura (1978), la creación de la mayor parte de las áreas protegidas del país (1979), y la Ley Forestal y de Vida Silvestre (1981). El moderno enfoque ambiental del Estado surgió en ese período inmediatamente posterior. Al situarnos en el período anterior a la plena formalización de las políticas públicas ambientales, buscamos mostrar distintas vertientes y corrientes que confluirán en el proceso de “institucionalización” de las preocupaciones por la protección ambiental en el Estado ecuatoriano hacia los años 1950. El interés que guía esta indagación preliminar es el de mostrar el proceso de formación de los mecanismos de “gobierno” del patrimonio natural del país, es decir, los medios e instrumentos que sirven para regular tanto el acceso como el uso de dicho patrimonio para fines humanos. Tanto en políticas públicas como en ciencias sociales, se detecta un creciente interés en la consideración de los sistemas de “gobernanza” del patrimonio ambiental aunque el término es todavía objeto de muchas controversias y se usa para indicar combinaciones variables de mecanismos de participación social, presencia empresarial y regulación estatal.4 Por nuestra parte, este artículo se concentra en la formación de las organizaciones estatales encargadas de llevar a cabo la vigilancia, el control y la regulación de acceso y uso al patrimonio ambiental del país. La hipótesis general de la que partimos es que a partir de las primeras décadas del siglo XX se han ido desarrollando paulatinamente mecanismos que progresivamente desplazan una parte del control de los medios de manejo del patrimonio ambiental del país desde una serie de actores privados y comunitarios hacia el Estado. Aunque la parte del control ambiental que se desplaza es pequeña, no es en modo alguno desdeñable.

Negative correlations between control performance and verbalizable knowledge: indicators for implicit learning in process control tasks?

Negative correlations between task performance in dynamic control tasks and verbalizable knowledge, as assessed by a post-task questionnaire, have been interpreted as dissociations that indicate two antagonistic modes of learning, one being “explicit”, the other “implicit”. This paper views the control tasks as finite-state automata and offers an alternative interpretation of these negative correlations. It is argued that “good controllers” observe fewer different state transitions and, consequently, can answer fewer post-task questions about system transitions than can “bad controllers”. Two experiments demonstrate the validity of the argument by showing the predicted negative relationship between control performance and the number of explored state transitions, and the predicted positive relationship between the number of explored state transitions and questionnaire scores. However, the experiments also elucidate important boundary conditions for the critical effects. We discuss the implications of these findings, and of other problems arising from the process control paradigm, for conclusions about implicit versus explicit learning processes.

Computational modes and grid imprinting on five quasi-uniform spherical C-grids

Currently, most operational forecasting models use latitude-longitude grids, whose convergence of meridians towards the poles limits parallel scaling. Quasi-uniform grids might avoid this limitation. Thuburn et al, JCP, 2009 and Ringler et al, JCP, 2010 have developed a method for arbitrarily-structured, orthogonal C-grids (TRiSK), which has many of the desirable properties of the C-grid on latitude-longitude grids but which works on a variety of quasi-uniform grids. Here, five quasi-uniform, orthogonal grids of the sphere are investigated using TRiSK to solve the shallow-water equations. We demonstrate some of the advantages and disadvantages of the hexagonal and triangular icosahedra, a Voronoi-ised cubed sphere, a Voronoi-ised skipped latitude-longitude grid and a grid of kites in comparison to a full latitude-longitude grid. We will show that the hexagonal-icosahedron gives the most accurate results (for least computational cost). All of the grids suffer from spurious computational modes; this is especially true of the kite grid, despite it having exactly twice as many velocity degrees of freedom as height degrees of freedom. However, the computational modes are easiest to control on the hexagonal icosahedron since they consist of vorticity oscillations on the dual grid which can be controlled using a diffusive advection scheme for potential vorticity.

The Aqua-Planet Experiment (APE): CONTROL SST Simulation

Climate simulations by 16 atmospheric general circulation models (AGCMs) are compared on an aqua-planet, a water-covered Earth with prescribed sea surface temperature varying only in latitude. The idealised configuration is designed to expose differences in the circulation simulated by different models. Basic features of the aqua-planet climate are characterised by comparison with Earth. The models display a wide range of behaviour. The balanced component of the tropospheric mean flow, and mid-latitude eddy covariances subject to budget constraints, vary relatively little among the models. In contrast, differences in damping in the dynamical core strongly influence transient eddy amplitudes. Historical uncertainty in modelled lower stratospheric temperatures persists in APE. Aspects of the circulation generated more directly by interactions between the resolved fluid dynamics and parameterized moist processes vary greatly. The tropical Hadley circulation forms either a single or double inter-tropical convergence zone (ITCZ) at the equator, with large variations in mean precipitation. The equatorial wave spectrum shows a wide range of precipitation intensity and propagation characteristics. Kelvin mode-like eastward propagation with remarkably constant phase speed dominates in most models. Westward propagation, less dispersive than the equatorial Rossby modes, dominates in a few models or occurs within an eastward propagating envelope in others. The mean structure of the ITCZ is related to precipitation variability, consistent with previous studies. The aqua-planet global energy balance is unknown but the models produce a surprisingly large range of top of atmosphere global net flux, dominated by differences in shortwave reflection by clouds. A number of newly developed models, not optimised for Earth climate, contribute to this. Possible reasons for differences in the optimised models are discussed. The aqua-planet configuration is intended as one component of an experimental hierarchy used to evaluate AGCMs. This comparison does suggest that the range of model behaviour could be better understood and reduced in conjunction with Earth climate simulations. Controlled experimentation is required to explore individual model behaviour and investigate convergence of the aqua-planet climate with increasing resolution.

Impact of global warming on the interannual and interdecadal climate modes in a coupled GCM

In this study, we investigated the impact of global warming on the variabilities of large-scale interannual and interdecadal climate modes and teleconnection patterns with two long-term integrations of the coupled general circulation model of ECHAM4/OPYC3 at the Max-Planck-Institute for Meteorology, Hamburg. One is the control (CTRL) run with fixed present-day concentrations of greenhouse gases. The other experiment is a simulation of transient greenhouse warming, named GHG run. In the GHG run the averaged geopotential height at 500 hPa is increased significantly, and a negative phase of the Pacific/North American (PNA) teleconnection-like distribution pattern is intensified. The standard deviation over the tropics (high latitudes) is enhanced (reduced) on the interdecadal time scales and reduced (enhanced) on the interannual time scales in the GHG run. Except for an interdecadal mode related to the Southern Oscillation (SO) in the GHG run, the spatial variation patterns are similar for different (interannual + interdecadal, interannual, and interdecadal) time scales in the GHG and CTRL runs. Spatial distributions of the teleconnection patterns on the interannual and interdecadal time scales in the GHG run are also similar to those in the CTRL run. But some teleconnection patterns show linear trends and changes of variances and frequencies in the GHG run. Apart from the positive linear trend of the SO, the interdecadal modulation to the El Niño/SO cycle is enhanced during the GHG 2040 ∼ 2099. This is the result of an enhancement of the Walker circulation during that period. La Niña events intensify and El Niño events relatively weaken during the GHG 2070 ∼ 2090. It is interesting to note that with increasing greenhouse gas concentrations the relation between the SO and the PNA pattern is reversed significantly from a negative to a positive correlation on the interdecadal time scales and weakened on the interannual time scales. This suggests that the increase of the greenhouse gas concentrations will trigger the nonstationary correlation between the SO and the PNA pattern both on the interdecadal and interannual time scales.

'You show me yours, I'll show you mine': the negotiation of shifts from textual to visual modes in computer-mediated interaction among gay men

This article explores the way users of an online gay chat room negotiate the exchange of photographs and the conduct of video conferencing sessions and how this negotiation changes the way participants manage their interactions and claim and impute social identities. Different modes of communication provide users with different resources for the control of information, affecting not just what users are able to reveal, but also what they are able to conceal. Thus, the shift from a purely textual mode for interacting to one involving visual images fundamentally changes the kinds of identities and relationships available to users. At the same time, the strategies users employ to negotiate these shifts of mode can alter the resources available in different modes. The kinds of social actions made possible through different modes, it is argued, are not just a matter of the modes themselves but also of how modes are introduced into the ongoing flow of interaction.

Abrupt transitions in the NAO control of explosive North Atlantic cyclone development

Explosive cyclones are intense extra-tropical low pressure systems featuring large deepening rates. In the Euro-Atlantic sector, they are a major source of life-threatening weather impacts due to their associated strong wind gusts, heavy precipitation and storm surges. The wintertime variability of the North Atlantic cyclonic activity is primarily modulated by the North Atlantic Oscillation (NAO). In this study, we investigate the interannual and multi-decadal variability of explosive North Atlantic cyclones using track density data from two reanalysis datasets (NCEP and ERA-40) and a control simulation of an atmosphere/ocean coupled General Circulation Model (GCM—ECHAM5/MPIOM1). The leading interannual and multi-decadal modes of variability of explosive cyclone track density are characterized by a strengthening/weakening pattern between Newfoundland and Iceland, which is mainly modulated by the NAO at both timescales. However, the NAO control of interannual cyclone variability is not stationary in time and abruptly fluctuates during periods of 20–25 years long both in NCEP and ECHAM5/MPIOM1. These transitions are accompanied by structural changes in the leading mode of explosive cyclone variability, and by decreased/enhanced baroclinicity over the sub-polar/sub-tropical North Atlantic. The influence of the ocean is apparently important for both the occurrence and persistence of such anomalous periods. In the GCM, the Atlantic Meridional Overturning Circulation appears to influence the large-scale baroclinicity and explosive cyclone development over the North Atlantic. These results permit a better understanding of explosive cyclogenesis variability at different climatic timescales and might help to improve predictions of these hazardous events.

Transport control in fusion plasmas by changing electric and magnetic field spatial profiles

For magnetically confined plasmas in tokamaks, we have numerically investigated how Lagrangian chaos at the plasma edge affects the plasma confinement. Initially, we have considered the chaotic motion of particles in an equilibrium electric field with a monotonic radial profile perturbed by drift waves. We have showed that an effective transport barrier may be created at the plasma edge by modifying the electric field radial profile. In the second place, we have obtained escape patterns and magnetic footprints of chaotic magnetic field lines in the region near a tokamak wall with resonant modes due to the action of an ergodic magnetic limiter. For monotonic plasma current density profiles we have obtained distributions of field line connections to the wall and line escape channels with the same spatial pattern as the magnetic footprints on the tokamak walls. (c) 2008 Elsevier B.V. All rights reserved.

Intersection of autonomy and social control : negotiating teenage motherhood

Contrary to popular belief, teenage mothers are a declining proportion of birthing women; however they receive much negative public attention. Of particular public concern is the high cost of supporting teenage mothers, in terms of financial, health and welfare resources. Historically, the typical founding mother of white Australia was single, but post-war changes in the family structure incorporated the expectation that children be born into two-parent households with the male as the breadwinner. Policy changes in the seventies saw the introduction of the Sole Parents Pension which meant that many birthing teenage women could choose to keep their infants rather than have a clandestine adoption or an enforced marriage. The parenting practices of teenage mothers have been criticised for being less than optimal, and mother and child are reported as being disadvantaged cognitively, psychosocially, and educationally. One widespread nursing service which provides support for new mothers in Victoria is the Maternal and Child Health Service; however, teenage mothers appear reluctant to use such services. Why this should be so became an important question for this research, since little is known about the parenting practices of teenage mothers. This study therefore sought to explore mothering from the perspective of five sole supporting teenage mothers each of whom had a child over six months of age. The research methodology took an interpretive ethnographic approach and was guided by feminist principles. The data were collected through repeated interviewing, participant observation, informal discussions with key informants, field notes and journalling. Data analysis was aided by the use of the software, program NUD-IST. It was found that the young women in this study each chose to give birth with full realisation that their existence was dependent on the Welfare State. Unanticipated, however, were the many structural barriers which made their lives cataclysmic, but these reinforced their determination to prove themselves worthy and capable mothers. The young women negotiated motherhood through a range of social supports and through maternal practice. Unquestionably, their social dependency on the welfare system forced them into marginal citizen status. Moreover, absolute and intrinsic poverty levels were experienced, brought about by inadequate welfare payments. Formal support agencies, such as the Maternal and Child Health nurses were rarely approached to provide childrearing support beyond the initial months following birthing, since the teenagers' basic needs such as shelter, food and clothing took precedence over their parenting needs. Additionally, some nurses were perceived to hold judgmental attitudes towards teenage mothers. It was far easier to forestall confrontation with nurses and the other 'older' women clientele by avoiding them. Thus XI they turned to charitable agencies who provided a safety net in the form of emergency supplies of money, food, or equipment. Informal networks of friends provided alternative modes of support when family help failed to materialise. The children, however, provided the young women with an opportunity to transform their lives by breaking free of the past, and by creating a new, mature existence for themselves. Despite being abandoned by family, friends, lovers and society, in the privacy and isolation of their own homes, they attempted to provide a more nurturing environment for their children than they themselves had received. Each bestowed unconditional maternal love on the child and were rewarded through the pleasures of watching their children grow and develop into worthwhile individuals. The children became the focus of their attention and their reason for living. In the course of their welfare dependency, the young women became public property, targets of surveillance, and were subjected to stigmatising and condescending public attitudes wherever they went. In this way, it was evident that they were an oppressed group, but each found ways of resisting. Rather than focussing on their oppressive or disabling lives, or dwelling on their disadvantaged status, the young women sought their identities as mature women through motherhood and by demonstrating that they could do this important job well. Through motherhood their lives had meaning and a sense of purpose. The thesis concludes that motherhood in the teenage years is difficult. However, if appropriate supports are made available, teenage mothers need be no different from non-teenage mothers. But with state resources shrinking, and their own resources limited, teenage mothers are disadvantaged. In some ways, this study showed that all levels of support were inadequate, although those provided through the charitable organizations were seen to be the most appropriate. This reflects the current policy of economic rationalism adopted by most Western liberal democracies in the 1980s and 1990s and no less by the former Keating Labor Government in Australia.