Symmetron Cosmology

The symmetron is a scalar field associated with the dark sector whose coupling to matter depends on the ambient matter density. The symmetron is decoupled and screened in regions of high density, thereby satisfying local constraints from tests of gravity, but couples with gravitational strength in regions of low density, such as the cosmos. In this paper we derive the cosmological expansion history in the presence of a symmetron field, tracking the evolution through the inflationary, radiation- and matter-dominated epochs, using a combination of analytical approximations and numerical integration. For a broad range of initial conditions at the onset of inflation, the scalar field reaches its symmetry-breaking vacuum by the present epoch, as assumed in the local analysis of spherically-symmetric solutions and tests of gravity. For the simplest form of the potential, the energy scale is too small for the symmetron to act as dark energy, hence we must add a cosmological constant to drive late-time cosmic acceleration. We briefly discuss a class of generalized, non-renormalizable potentials that can have a greater impact on the late-time cosmology, though cosmic acceleration requires a delicate tuning of parameters in this case.Comment: 42 page

Social capital: A vital ingredient for retaining foreign language teachers

Introduction A major source of concern across a number of English-speaking countries is the loss of language teachers from the profession. In a global era where the ability to engage across languages and cultures is seen as vital for international engagement, this poses a significant problem as teacher shortages continue to challenge the efficacy of language education programs. And yet, there are very few large-scale studies which investigate the career attrition of foreign language teachers. The Australian mixed methods study reported here investigated the relationship between social capital and the career retention of 227 foreign language teachers. Results The findings expand our understanding of language teacher attrition, by showing that teachers who felt professionally valued and who had strong relationships with their colleagues and administrative leaders were less likely to leave language teaching. It was also found that social bonds with other foreign language teachers were an important form of social capital proactively sought by many language teachers, to help them overcome their professional isolation and thus maintain their professional standards. However, these strong social bonds were found to play a role in promoting language teacher attrition, as they provide teachers with a ladder to other career opportunities. Conclusions This study concludes that some language teachers are lacking in social capital, and that this lack of social capital is a key driver in career attrition. Therefore, there is a need to develop policies, and engage in practices, which facilitate and encourage the further development of language teachers' social capital. The conclusion of this paper explores ways to move forward to improve the retention of language teachers

Language teacher supply: A content analysis of newspaper coverage across the 'Anglobubble'

In the monolingual English-speaking world referred to as the ‘Anglobubble’, governments are finally recognising the advantages of a citizenry able to engage in and between multiple languages and cultures. As a result, increased efforts are being made to introduce and expand educational programs to teach languages. Thus, now more than ever, an appropriate language teacher supply is needed to support the internationalisation process of citizens. However, a language teacher supply crisis is emerging. The content analysis study reported here, explored how the issue of language teacher supply was portrayed in print-based newspaper media from six English-speaking countries between 2010 and 2015. The findings indicate that there is an ongoing crisis with the supply of language teachers in Australia, Canada, New Zealand, the United Kingdom and the United States. Further, in areas where language education is being propelled by top-down political agendas, sustainable progress is limited. Attention is focused on a small number of ‘popular’ languages, with indigenous languages all but forgotten. In contrast, in areas where grass-roots community movements are present, actions are being undertaken to find genuine and sustainable solutions. This is also bringing a more positive media discourse, and, as such, increased social awareness of and value for language education

Progressive Probabilistic Hough Transform for line detection

We present a novel Hough Transform algorithm referred to as Progressive Probabilistic Hough Transform (PPHT). Unlike the Probabilistic HT where Standard HT is performed on a pre-selected fraction of input points, PPHT minimises the amount of computation needed to detect lines by exploiting the difference an the fraction of votes needed to detect reliably lines with different numbers of supporting points. The fraction of points used for voting need not be specified ad hoc or using a priori knowledge, as in the probabilistic HT; it is a function of the inherent complexity of the input data. The algorithm is ideally suited for real-time applications with a fixed amount of available processing time, since voting and line detection is interleaved. The most salient features are likely to be detected first. Experiments show that in many circumstances PPHT has advantages over the Standard HT

Transcripcional, functional and virulence analysis of a Pseudomonas Savastanoi pv. savastanoi genomic region shared with other pathogens of woody hosts

Comunicación al XVI congreso de la Sociedad Internacional de Interacciones moleculares Planta-PatógenoThe genome of the olive tree pathogen Pseudomonas savastanoi pv. savastanoi (Psv) NCPPB3335 (58.1% G+C) encodes a region of about 15 kb, named VR8 (60.4% G+C), which is absent in all sequenced Pseudomonas syringae strains infecting herbaceous plants, but shared with P. syringae pathovars infecting woody hosts. RT-PCR analysis of the VR8 genes revealed the existence of 4 possible operons, of which the antABC and catBCA operons are involved in the degradation of anthranilate and catechol, respectively. The antABC cluster is homologous to the anthranilate degradation genes found on plasmid pCAR1 of Pseudomonas resinovorans. The other two operons, here called AER-1901/2/3 and AER-1904/5, also show homology to genes related with the degradation of aromatic compounds. RT-qPCR and ß-galactosidase assays of a LacZ fusions showed that both anthranilate and 6-chloro-antrhanilate induce the antABC operon. In addition, anthranilate also induces the catB gene. To analyse the role in virulence of the VR8, we constructed several knockout mutants of this region. The volume of the knots induced in non lignified olive plants by Psv mutants affected in the antABC or catBCA operons resulted to be similar to those induced by the wild-type strain. However, the severity of the symptoms generated by the antABC mutant in lignified olive plants was significantly lower than that induced by the wildtype strain, suggesting a possible role of this operon in the degradation of lignin-derived compounds. At present, we are analysing the role in virulence of the other three operons and of the AER-1900 gene (a putative aerotaxis receptor).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Los Eucaliptos en las tierras altas de Angola, su papel social durante el conflicto armado y en el desarrollo de las comunidades rurales y urbanas

Las tierras altas de Angola han tenido un complicado desarrollo histórico desde que fueron colonizadas a inicios del siglo XX. Este proceso histórico también ha afectado a los bosques naturales y las plantaciones de eucaliptos que se crearon durante los años 60 y 70. El uso de estas plantaciones, inicialmente planificadas como suministro de combustible y materias primas para la industria colonial, se vio truncado con la independencia y los posteriores avatares políticomilitares. En la nueva situación de inseguridad en el medio rural, se convirtieron en la principal fuente de combustible para la creciente población urbana que huía del campo. Actualmente, los polígonos forestales sobrevivientes pueden ser utilizados en la rehabilitación de esta zona del país. El objetivo de este trabajo de investigación es conocer el proceso histórico de uso y gestión de estas plantaciones su papel social en este proceso y la situación en la que se encuentran actualmente._________________________________The Angolan highlands were involved in a complicated historical process since the beginning of colonization in the early 1900´s. The process also affected the natural forest and eucalyptus plantations that were implanted in the sixties and seventies. Its primary planning uses were for fuel wood and timber supply to the colonial industries. The forest uses changed with the independence and the later war conflicts. The insecurity in the rural areas caused a strong rural peasant migration to the more secure cities. Forest plantation close to cities became the main fuel wood supply for the growing urban population. Currently, some forest plantations remain in the less accessible areas and can be use for the rehabilitation of the region. The main objective of the research was to increase the knowledge concern the eucalyptus forests uses and management during the historical process, its social importance during the war time and the state of the forests in present days

Wearable face recognition aid

The feasibility of realising a low cost wearable face recognition aid based on a robust correlation algorithm is investigated. The aim of the study is to determine the limiting spatial and grey level resolution of the probe and gallery images that would support successful prompting of the identity of input face images. Low spatial and grey level resolution images are obtained from good quality image data algorithmically. The tests carried out on the XM2VTS database demonstrate that robust correlation is very resilient to degradations of spatial and grey level image resolution. Correct prompts have been generated in 98% cases even for severely degraded images

Advanced Synchronization Control for Inverters Parallel Operation in Microgrids Using Coupled Hopf Oscillators

A simple high-performance decentralized controller based on Hopf oscillator is proposed for three-phase parallel voltage source inverter (VSI) in islanded Microgrid. In aß frame, the oscillators equations corresponding output current and com-mon bus voltage as feedbacks are designed according to coupled oscillator synchronization properties. The enough common bus information is considered to realize external synchronization, and the current feedback is to achieve internal synchronization between VSIs. Then, the controller employs Hopf evolution dynamics to integrate their both. Therefore, a larger phase error can be eliminated when additional inverter connects, and the pre-synchronization item is proposed to be close to synchronize with the operational inverters. In addition, an integrated small-signal states pace based on averaged model for two parallel VSIs is developed, and the root locus shows the large stability margin and low sensitivity of parameters. Simulation and experiment results verifi ed the effectiveness of the proposed method in aspects of the fast dynamics response and precise current sharing performance.Peer ReviewedPostprint (published version

A Fast Power Calculation Algorithm for Three-Phase Droop-Controlled-Inverters Using Combined SOGI Filters and Considering Nonlinear Loads

The power calculation is an indispensable element in droop-controlled inverters because the bandwidth of the measured power has a direct impact on the controller performance. This paper proposes a fast and accurate power calculation algorithm based on the combined Second Order Generalized Integrator (SOGI) filters in stationary coordinates for a three-phase system, which takes into consideration the use of nonlinear loads. The power calculation scheme is formed by the two-stage SOGI filters that are employed for obtaining the active and reactive powers required to perform a droop-based inverter operation, respectively. From the two-stage structure, the first SOGI is used as a band-pass filter (BPF) for filtering harmonics and obtaining the fundamental current of the nonlinear load; The second SOGI is used as a low-pass filter (LPF) for extracting the DC-component, which corresponds with the average power. A small-signal model of a two droop-controlled inverters system is built to obtain the dynamical response and stability margin of the system. And compared it with the dynamical behaviour of a standard droop-control method. Next, the proposed power calculation system is designed in order to achieve the same ripple amplitude voltage as that obtained with the standard droop-control method by adjusting the bandwidth gains. Through simulation and hardware in the loop (HIL) validation, the proposed approach presents a faster and more accurate performance when sharing nonlinear loads, and also drives the inverters’ output voltage with lower distortion.Peer ReviewedPostprint (published version