Maize streak virus: An old and complex 'emerging' pathogen

Maize streak virus (MSV; Genus Mastrevirus, Family Geminiviridae) occurs throughout Africa, where it causes what is probably the most serious viral crop disease on the continent. It is obligately transmitted by as many as six leafhopper species in the Genus Cicadulina, but mainly by C. mbila Naudé and C. storeyi. In addition to maize, it can infect over 80 other species in the Family Poaceae. Whereas 11 strains of MSV are currently known, only the MSV-A strain is known to cause economically significant streak disease in maize. Severe maize streak disease (MSD) manifests as pronounced, continuous parallel chlorotic streaks on leaves, with severe stunting of the affected plant and, usuallly, a failure to produce complete cobs or seed. Natural resistance to MSV in maize, and/or maize infections caused by non-maize-adapted MSV strains, can result in narrow, interrupted streaks and no obvious yield losses. MSV epidemiology is primarily governed by environmental influences on its vector species, resulting in erratic epidemics every 3-10 years. Even in epidemic years, disease incidences can vary from a few infected plants per field, with little associated yield loss, to 100% infection rates and complete yield loss. Taxonomy: The only virus species known to cause MSD is MSV, the type member of the Genus Mastrevirus in the Family Geminiviridae. In addition to the MSV-A strain, which causes the most severe form of streak disease in maize, 10 other MSV strains (MSV-B to MSV-K) are known to infect barley, wheat, oats, rye, sugarcane, millet and many wild, mostly annual, grass species. Seven other mastrevirus species, many with host and geographical ranges partially overlapping those of MSV, appear to infect primarily perennial grasses. Physical properties: MSV and all related grass mastreviruses have single-component, circular, single-stranded DNA genomes of approximately 2700 bases, encapsidated in 22 × 38-nm geminate particles comprising two incomplete T = 1 icosahedra, with 22 pentameric capsomers composed of a single 32-kDa capsid protein. Particles are generally stable in buffers of pH 4-8. Disease symptoms: In infected maize plants, streak disease initially manifests as minute, pale, circular spots on the lowest exposed portion of the youngest leaves. The only leaves that develop symptoms are those formed after infection, with older leaves remaining healthy. As the disease progresses, newer leaves emerge containing streaks up to several millimetres in length along the leaf veins, with primary veins being less affected than secondary or tertiary veins. The streaks are often fused laterally, appearing as narrow, broken, chlorotic stripes, which may extend over the entire length of severely affected leaves. Lesion colour generally varies from white to yellow, with some virus strains causing red pigmentation on maize leaves and abnormal shoot and flower bunching in grasses. Reduced photosynthesis and increased respiration usually lead to a reduction in leaf length and plant height; thus, maize plants infected at an early stage become severely stunted, producing undersized, misshapen cobs or giving no yield at all. Yield loss in susceptible maize is directly related to the time of infection: Infected seedlings produce no yield or are killed, whereas plants infected at later times are proportionately less affected. Disease control: Disease avoidance can be practised by only planting maize during the early season when viral inoculum loads are lowest. Leafhopper vectors can also be controlled with insecticides such as carbofuran. However, the development and use of streak-resistant cultivars is probably the most effective and economically viable means of preventing streak epidemics. Naturally occurring tolerance to MSV (meaning that, although plants become systemically infected, they do not suffer serious yield losses) has been found, which has primarily been attributed to a single gene, msv-1. However, other MSV resistance genes also exist and improved resistance has been achieved by concentrating these within individual maiz genotypes. Whereas true MSV immunity (meaning that plants cannot be symptomatically infected by the virus) has been achieved in lines that include multiple small-effect resistance genes together with msv-1, it has proven difficult to transfer this immunity into commercial maize genotypes. An alternative resistance strategy using genetic engineering is currently being investigated in South Africa. Useful websites: 〈http://www.mcb.uct.ac.za/MSV/mastrevirus.htm〉; 〈http://www. danforthcenter.org/iltab/geminiviridae/geminiaccess/mastrevirus/Mastrevirus. htm〉. © 2009 Blackwell Publishing Ltd.

TiltZoom : tilt-based zooming control for easy one-handed mobile interactions

In this paper, we present TiltZoom, a collection of tilt-based interaction techniques designed for easy one-handed zooming on mobile devices. TiltZoom represents novel gestural interaction techniques, implemented using rate-of-rotation readings from a gyroscope, a sensor commonly embedded on current generation smart phones. We designed and experimented three variants of TiltZoom - Tilt Level, Tilt and Hold and Flip Gesture. The design decisions for all three variants are discussed in this paper and their performance, as well as subjective user experience are evaluated and compared against conventional touch-based zooming techniques. TiltZoom appears to be a worthy addition to current established collection of gesture-based mobile interaction techniques for zooming controls, especially when user has only one hand available when moving about.

Assessing food insecurity : current underestimations in Australia, alternative measures and reflections on their use

Food insecurity is the limited access to, or availability of, nutritious, culturally-appropriate and safe foods, or the inability to access these foods by socially acceptable means. In Australia, the monitoring of food insecurity is limited to the use of a single item, included in the three-yearly National Health Survey (NHS). The current research comprised a) a review of the literature and available tools to measure food security, b) piloting and adaptation of the more comprehensive 16-item United States Department of Agriculture (USDA) Food Security Survey Module (FSSM), and c) a cross-sectional study comparing this more comprehensive tool, and it’s 10- and 6- item short forms, with the current single-item used in the NHS, among a sample of households in disadvantaged urban-areas of Brisbane, Australia. Findings have shown that internationally the 16-item USDA-FSSM is the most widely used tool for the measurement of food insecurity. Furthermore, of the validated tools that exist to measure food insecurity, sensitivity and reliability decline as the number of questions in a tool decreases. Among an Australian sample, the current single-measure utilised in the NHS yielded a significantly lower prevalence for food insecurity compared to the 16-item USDA-FSSM and it’s two shorter forms respectively (four and two percentage points lower respectively). These findings suggest that the current prevalence of food insecurity (estimated at 6% in the most recent NHS) may have been underestimated, and have important implications for the development of an effective means of monitoring food security within the context of a developed country.

Why do policy decision-makers opt for command and control environmental regulation? An economic analysis with special reference to Sri Lanka

This chapter examines why policy decision-makers opt for command and control environmental regulation despite the availability of a plethora of market-based instruments which are more efficient and cost-effective. Interestingly, Sri Lanka has adopted a wholly command and control system, during both the pre and post liberalisation economic policies. This chapter first examines the merits and demerits of command and control and market-based approaches and then looks at Sri Lanka’s extensive environmental regulatory framework. The chapter then examines the likely reasons as to why the country has gone down the path of inflexible regulatory measures and has become entrenched in them. The various hypotheses are discussed and empirical evidence is provided. The chapter also discusses the consequences of an environmentally slack economy and policy implications stemming from adopting a wholly regulatory approach. The chapter concludes with a discussion of the main results.

Politicians as experts, electoral control, and fiscal restraints

We establish an argument for fiscal restraints which is based on the idea that politicians are experts in the meaning of the credence good literature. A budget maximizing politician is better informed than the electorate about the necessary spending to ensure the states ability to provide services for the economy. Voters, being able to observe the budget but not the necessary level of spending, attenuate the government’s spending level via electoral control. A fiscal restraint limits the maximum spending a government will choose if the level of spending ensuring the politicians reelection is not sufficient to ensure the state’s ability to provide services to the economy. We determine when such a fiscal restraint improves voter welfare and discuss the role of the opposition in situations where very high levels of spending are required.

An intelligent network control system for plug-in electric vehicles and the associate communication mechanism

The development of an intelligent plug-in electric vehicle (PEV) network is an important research topic in the smart grid environment. An intelligent PEV network enables a flexible control of PEV charging and discharging activities and hence PEVs can be utilized as ancillary service providers in the power system concerned. Given this background, an intelligent PEV network architecture is first developed, and followed by detailed designs of its application layers, including the charging and discharging controlling system, mobility and roaming management, as well as communication mechanisms associated. The presented architecture leverages the philosophy in mobile communication network buildup

Optimising COBIT 5 for IT governance : examples from the public sector

Control Objectives for Information and related Technology (COBIT) has grown to be one of the most significant IT Governance (ITG) frameworks available and also the best suited for audit, as it provides comprehensive guidance around IT processes and related business goals. However, given the constraints of both time and resources within which the Australian public sector is forced to operate, implementing an audit framework the size of COBIT in its entirety is often considered too large a task. As an alternative to full implementation it is not uncommon for the public sector to “cherry pick” controls from the framework in an effort to reduce its size. This paper reports on research undertaken to evaluate the potential to use an optimised sub-set of COBIT 5 for ITG audit in Australian public sector organisations. A survey methodology was employed to determine the control-objectives considered to be the most important to a selection of public sector organisations. Twelve control-objectives were identified as being most important to Queensland public sector organisations. As ten of these were also identified by previous studies, it appears possible to derive an optimised sub-set from COBIT 5 that would be both enduring and relevant across geographical and organisational contexts.

Budget-aware role based access control

The suitability of Role Based Access Control (RBAC) is being challenged in dynamic environments like healthcare. In an RBAC system, a user's legitimate access may be denied if their need has not been anticipated by the security administrator at the time of policy specification. Alternatively, even when the policy is correctly specified an authorised user may accidentally or intentionally misuse the granted permission. The heart of the challenge is the intrinsic unpredictability of users' operational needs as well as their incentives to misuse permissions. In this paper we propose a novel Budget-aware Role Based Access Control (B-RBAC) model that extends RBAC with the explicit notion of budget and cost, where users are assigned a limited budget through which they pay for the cost of permissions they need. We propose a model where the value of resources are explicitly defined and an RBAC policy is used as a reference point to discriminate the price of access permissions, as opposed to representing hard and fast rules for making access decisions. This approach has several desirable properties. It enables users to acquire unassigned permissions if they deem them necessary. However, users misuse capability is always bounded by their allocated budget and is further adjustable through the discrimination of permission prices. Finally, it provides a uniform mechanism for the detection and prevention of misuses.

Bone tissue engineering

Currently, well-established clinical therapeutic approaches for bone reconstruction are restricted to the transplantation of autografts and allografts, and the implantation of metal devices or ceramic-based implants to assist bone regeneration. These standard techniques face significant disadvantages. As a result, research has focused on the development of alternative therapeutic concepts aiming to design and engineer unparalleled structural and functional bone grafts. Substantial academic and commercial interest has been sparked in bone engineering methods to stimulate, control and eventually replicate key events of bone regeneration ex vivo. Over the years, this interest has further increased and bone tissue engineering has now become a well-recognized research discipline in the area of regenerative medicine. The following chapter gives an overview of bone tissue engineering principles. It focuses on research related to the combination of scaffolds with multipotent precursor cells, such as bone marrow-derived mesenchymal stem cells or human umbilical cord perivascular cells, and the clinical applications of these tissue engineered bone constructs.

Collective dynamics and control of a 3-D small-world network with time delays

The paper presents a detailed analysis on the collective dynamics and delayed state feedback control of a three-dimensional delayed small-world network. The trivial equilibrium of the model is first investigated, showing that the uncontrolled model exhibits complicated unbounded behavior. Then three control strategies, namely a position feedback control, a velocity feedback control, and a hybrid control combined velocity with acceleration feedback, are then introduced to stabilize this unstable system. It is shown in these three control schemes that only the hybrid control can easily stabilize the 3-D network system. And with properly chosen delay and gain in the delayed feedback path, the hybrid controlled model may have stable equilibrium, or periodic solutions resulting from the Hopf bifurcation, or complex stranger attractor from the period-doubling bifurcation. Moreover, the direction of Hopf bifurcation and stability of the bifurcation periodic solutions are analyzed. The results are further extended to any "d" dimensional network. It shows that to stabilize a "d" dimensional delayed small-world network, at least a "d – 1" order completed differential feedback is needed. This work provides a constructive suggestion for the high dimensional delayed systems.

Protein monoubiquitination and polyubiquitination generate structural diversity to control distinct biological processes

Ubiquitination involves the attachment of ubiquitin (Ub) to lysine residues on substrate proteins or itself, which can result in protein monoubiquitination or polyubiquitination. Polyubiquitination through different lysines (seven) or the N-terminus of Ub can generate different protein-Ub structures. These include monoubiquitinated proteins, polyubiqutinated proteins with homotypic chains through a particular lysine on Ub or mixed polyubiquitin chains generated by polymerization through different Ub lysines. The ability of the ubiquitination pathway to generate different protein-Ub structures provides versatility of this pathway to target proteins to different fates. Protein ubiquitination is catalyzed by Ub-conjugating and Ub-ligase enzymes, with different combinations of these enzymes specifying the type of Ub modification on protein substrates. How Ub-conjugating and Ub-ligase enzymes generate this structural diversity is not clearly understood. In the current review, we discuss mechanisms utilized by the Ub-conjugating and Ub-ligase enzymes to generate structural diversity during protein ubiquitination, with a focus on recent mechanistic insights into protein monoubiquitination and polyubiquitination.

Students’ beliefs about willingness to access complementary and alternative therapies (CAT) training for future integration into psychology practice.

It is suggested that all psychologists gain basic training in the types of complementary and alternative therapies (CAT) their clients may be using. As psychology students are the next cohort of health professionals who will inform future initiatives in the field, it is important to first understand the factors which influence their decisions about CAT integration. Drawing on the Theory of Planned Behavior, we investigated the beliefs that differentiate between psychology students who are high or low on willingness to access training in CAT for future practice use. Psychology students (N = 106) completed a questionnaire assessing the likelihood of both positive and negative consequences of accessing training and utilizing CAT within a psychological practice, important others approval, and barriers preventing them from this integration behavior. Those students high compared to low on willingness more likely to endorse positive outcomes (e.g., offering a more holistic approach to therapy) of accessing CAT training for future practice use and to believe that important others (e.g., clients) would support this behavior. We identified important beliefs of student psychologists related to decisions about undertaking CAT training for future professional use and can inform educators and policy-makers about CAT training and integration in psychology practice.

The impact of anxiety on processing efficiency : implications for the attentional control theory

The Attentional Control Theory (ACT) proposes that high-anxious individuals maintain performance effectiveness (accuracy) at the expense of processing efficiency (response time), in particular, the two central executive functions of inhibition and shifting. In contrast, research has generally failed to consider the third executive function which relates to the function of updating. In the current study, seventy-five participants completed the Parametric Go/No-Go and n-back tasks, as well as the State-Trait Anxiety Inventory in order to explore the effects of anxiety on attention. Results indicated that anxiety lead to decay in processing efficiency, but not in performance effectiveness, across all three Central Executive functions (inhibition, set-shifting and updating). Interestingly, participants with high levels of trait anxiety also exhibited impaired performance effectiveness on the n-back task designed to measure the updating function. Findings are discussed in relation to developing a new model of ACT that also includes the role of preattentive processes and dual-task coordination when exploring the effects of anxiety on task performance.

Narratives of the 'everyday' in Rio de Janeiro's favelas : community photographers' attempts at generating alternative news values [Narrativas do cotidiano nas favelas do Rio de Janeiro: tentativas de construção de valores-notícia alternativos pelos fotógrafos populares]

Abstract This paper presents the partial results of an ongoing research project which investigates ethnographically community (photo)journalism media initiatives, in Rio de Janeiro, Brazil. The Viva Rio and Observatorio de Favelas (NGOs) run projects that provide favela residents with skills to take, edit and print their own (photo) journalism contents that enables community-based framing and documentation of favela live, personalities and issues. Three months of fieldwork related to these projects in Rio's favelas generated remarkable theoretical issues that represent the community photographers' attempt to establish counter news values by shifting the focus from poverty, shortages, violence and criminality to images of the ordinary life which included the myriad events that occurs in the day of the favelas. Resumo Este artigo apresenta os resultados parciais de uma pesquisa em andamento que, a partir do método etnográfico, investiga os projetos de comunicação comunitária, jornalismo e fotojornalismo, no Rio de Janeiro, Brasil. As organizações não-governamentais (ONGs) Viva Rio e Observatório de Favela apoiam projetos que objetivam tornar moradores de favelas capazes de produzir, editar e publicar as suas próprias narrativas sobre personagens e questões do cotidiano de suas comunidades. O trabalho de campo sobre estes projetos, realizado durante três meses nas favelas do Rio de Janeiro, forneceu questões teóricas relevantes que representam o esforço dos fotógrafos populares para estabelecer contra valores-notícia transferindo o foco da pobreza, escassez, violência e criminalidade para imagens do cotidiano que inclui uma miríade de eventos que acontecem no dia-a-dia das favelas.