Multitrophic interactions in a potato-aphid system

In interactions between plants, insect herbivores and natural enemies, resistant plant varieties and soil abiotic/biotic factors can affect natural enemies through changes in the plant or host insect. Interactions can be negative, neutral or positive in relation to herbivore populations. The majority of studies have used above-ground plant–insect–parasitoid systems and relatively few studies have included below-ground effects on above-ground tritrophic interactions. The aim of the present project was to understand how soil-based stress factors (nutrient availability and root pathogens) influence multitrophic interactions in a potato-aphid (Myzus persicae)-parasitoid (Aphidius colemani) system. Specific objectives were: to assess aphid performance on different potato cultivars under laboratory and field conditions; use aphid resistant and susceptible cultivars to assess the effects of soil nutrition and a plant pathogen (root-knot nematode) on aphid performance; conduct multifactorial ditrophic (aphid performance) and tritrophic (parasitism success) experiments with selected combinations of soil treatments; use olfactometry to determine whether plant volatiles are involved where significant tritrophic interactions occur between treatments. Potato cv. Anya, a cv derived from Desiree and Pink Fir Apple, was found to be consistently resistant to M. persicae compared with the three other cultivars tested (Desiree, Santé and Pink Fir Apple) in both laboratory experiments (UK) and field trials (Pakistan and UK). For Anya (resistant) and Desiree and Pink Fir Apple (susceptible), high levels of soil nutrients enhanced aphid performance, their parasitism by A. colemani, and adult parasitoid emergence. Root-knot nematodes had a negative effect on aphid performance at both low and high soil nutrition but had a positive effect on parasitism at low soil nutrition. Olfactometry showed Desiree to be more attractive to M. persicae compared with Anya. The work is discussed in relation to the development of pest management strategies for the control of M. persicae on potato

Static Enforcement of Role-Based Access Control

We propose a new static approach to Role-Based Access Control (RBAC) policy enforcement. The static approach we advocate includes a new design methodology, for applications involving RBAC, which integrates the security requirements into the system's architecture. We apply this new approach to policies restricting calls to methods in Java applications. We present a language to express RBAC policies on calls to methods in Java, a set of design patterns which Java programs must adhere to for the policy to be enforced statically, and a description of the checks made by our static verifier for static enforcement.Comment: In Proceedings WWV 2014, arXiv:1409.229

Bureaucracy and Pro-poor Change

This paper takes a political economy perspective in analysing the nature and causes on the decline in bureaucratic conduct. Section 1 lays out the details of this structure. Based on a logical model which places the bureaucracy within the larger context of the objective function of the state, the nature of the political process, the degree of centralisation and fragmentation of the bureaucratic structure and processes for monitoring and accountability of the bureaucracy, this model provides the basis for subsequent analysis. Section 2 provides a historical overview with regard to changes in the bureaucratic and political structure and the impact it had on the above mentioned balance between bureaucratic conduct and political compulsions. Section 3 then analyses the consequences on service delivery that this systematic weakening of the bureaucratic structure has had. Section 4 then critically assesses some of the recent attempts at bureaucratic reform in the light of the framework developed in Section 1. The conclusion then summarises the paper and draws implications for pro-poor change of the structure and conduct of the bureaucratic structure in PakistanPoverty, Poor, Bureaucracy

Bureaucracy and Pro-poor Change

Based on the premise that a functioning state is a necessary pre-requisite for pro-poor change, it is critical to investigate the role of the bureaucracy as a key catalyst in this process. Weber (1968) ascribes bureaucracies to be anchors of the modern nation state as their conduct is based on rational-legal norms. Bureaucracies, according to this ideal type, temper the populist urges of politicians who wish to execute policy unencumbered by rules and procedures. State success or failure in many cases, therefore, can be gauged by the degree to which this tensionbetween the rules based bureaucratic form of administration and populist politicsis resolved. Prognosis on pro-poor change in the light of the present and anticipated balance between bureaucratic procedures and political compulsions is thus an important area of inquiry. There is consensus that the disconnect between policy formulation and execution in Pakistan has widened considerably in the last three decades or so. And this is in spite of the fact of the generally acclaimed view that Pakistan inherited a well functioning and competent bureaucracy from the British Raj [Braibanti (1966)]. While part of the blame for this disconnect can be ascribed to incoherence in policy formulation on the part of the political leadershipboth civil and militarybut bureaucratic malfeasance, incompetence and corruption have been critical factors in the level of governance declining over time. This paper takes a political economy perspective in analysing the nature and causes on the decline in bureaucratic conduct. Section 1 lays out the details of this structure. Based on a logical model which places the bureaucracy within the larger context of the objective function of the state, the nature of the political process, the degree of centralisation and fragmentation of the bureaucratic structure and processes for monitoring and accountability of the bureaucracy, this model provides the basis for subsequent analysis. Section 2 provides a historical overview with regard to changes in the bureaucratic and political structure and the impact it had on the above mentioned balance between bureaucratic conduct and political compulsions. Section 3 then analyses the consequences on service delivery that this systematic weakening of the bureaucratic structure has had. Section 4 then critically assesses some of the recent attempts at bureaucratic reform in the light of the framework developed in Section 1. The conclusion then summarises the paper and draws implications for pro-poor change of the structure and conduct of the bureaucratic structure in Pakistan.bureaucracy, pro-poor change, consequences on service

Directional Sensitivity of Gaze-Collinearity Features in Liveness Detection

To increase the trust in using face recognition systems, these need to be capable of differentiating between face images captured from a real person and those captured from photos or similar artifacts presented at the sensor. Methods have been published for face liveness detection by measuring the gaze of a user while the user tracks an object on the screen, which appears at pre-defined, places randomly. In this paper we explore the sensitivity of such a system to different stimulus alignments. The aim is to establish whether there is such sensitivity and if so to explore how this may be exploited for improving the design of the stimulus. The results suggest that collecting feature points along the horizontal direction is more effective than the vertical direction for liveness detection

Biometric Liveness Detection Using Gaze Information

This thesis is concerned with liveness detection for biometric systems and in particular for face recognition systems. Biometric systems are well studied and have the potential to provide satisfactory solutions for a variety of applications. However, presentation attacks (spoofng), where an attempt is made at subverting them system by making a deliberate presentation at the sensor is a serious challenge to their use in unattended applications. Liveness detection techniques can help with protecting biometric systems from attacks made through the presentation of artefacts and recordings at the sensor. In this work novel techniques for liveness detection are presented using gaze information. The notion of natural gaze stability is introduced and used to develop a number of novel features that rely on directing the gaze of the user and establishing its behaviour. These features are then used to develop systems for detecting spoofng attempts. The attack scenarios considered in this work include the use of hand held photos and photo masks as well as video reply to subvert the system. The proposed features and systems based on them were evaluated extensively using data captured from genuine and fake attempts. The results of the evaluations indicate that gaze-based features can be used to discriminate between genuine and imposter. Combining features through feature selection and score fusion substantially improved the performance of the proposed features