Hemiparasitic plant impacts animal and plant communities across four trophic levels

1.Understanding the impact of species on community structure is a fundamental question in ecology. There is a growing body of evidence that suggests that both sub-dominant species and parasites can have a disproportionately large impact. 2.Here we report the impacts of an organism that is both subdominant and parasitic, the hemiparasite Rhinanthus minor. Whilst the impact of parasitic angiosperms on their hosts and, to a lesser degree, co-existing plant species, have been well characterized, much less is known about their impacts on higher trophic levels. 3.We experimentally manipulated field densities of the hemiparasite Rhinanthus minor in a species rich grassland, comparing the plant and invertebrate communities in plots where it was removed, at natural densities or at enhanced densities. 4.Plots with natural and enhanced densities of R. minor had lower plant biomass than plots without the hemiparasite, but enhanced densities almost doubled the abundance of invertebrates within the plots across all trophic levels, with effects evident in herbivores, predators and detritivores. 5.The hemiparasite R. minor, despite being a sub-dominant and transient component within plant communities that it inhabits, has profound effects on four different trophic levels. These effects persist beyond the life of the hemiparasite, emphasizing its role as a keystone species in grassland communitie

The influence of stratigraphy and facies distribution on reservoir quality and production performance in the Triassic Skagerrak Formation of the UK and Norwegian Central North Sea

Acknowledgements The Triassic Phase 2 Consortium members; BP, Total, JX Nippon & Cairn Energy are gratefully acknowledged for their support of this work. All reviewers are thanked for their comments and additions which undoubtedly improved the manuscript. Funding The work behind this paper was funded by a grant from the Triassic JIP Phase 2 award to AH.Peer reviewedPostprin

The Application of Network Analysis to the Study of Trial Courts

In the late 1960s, scholars began studying trial courts as organizations. Since the last large wave of these studies in the 1990s, there have been reforms that purport to alter state court institutions. The literature on trial courts has not yet addressed how reforms, like specialized courts, alter trial courts as organizations. Studies of trial courts could also profit from the application of other methods for analyzing organizations. This article explores the use of network analysis to examine the organizational linkages and structure of trial courts. After reviewing the literature on trial courts and recent court reforms, we make a case for the utility of this methodological approach. Recent computer applications of network analysis can visually map the linkages between trial court actors and the organizations that work with them. As a demonstration, we provide some of the results of our study of a state trial court located in a medium-size U.S. city. We conclude by arguing that network analysis as a technique can help scholars test past assumptions about the organization of courts and explore new linkages that are proposed by the adoption of court reforms

The Application of Network Analysis to the Study of Trial Courts

In the late 1960s, scholars began studying trial courts as organizations. Since the last large wave of these studies in the 1990s, there have been reforms that purport to alter state court institutions. The literature on trial courts has not yet addressed how reforms, like specialized courts, alter trial courts as organizations. Studies of trial courts could also profit from the application of other methods for analyzing organizations. This article explores the use of network analysis to examine the organizational linkages and structure of trial courts. After reviewing the literature on trial courts and recent court reforms, we make a case for the utility of this methodological approach. Recent computer applications of network analysis can visually map the linkages between trial court actors and the organizations that work with them. As a demonstration, we provide some of the results of our study of a state trial court located in a medium-size U.S. city. We conclude by arguing that network analysis as a technique can help scholars test past assumptions about the organization of courts and explore new linkages that are proposed by the adoption of court reforms

Model predictive control system design and implementation for spacecraft rendezvous

This paper presents the design and implementation of a model predictive control (MPC) system to guide and control a chasing spacecraft during rendezvous with a passive target spacecraft in an elliptical or circular orbit, from the point of target detection all the way to capture. To achieve an efficient system design, the rendezvous manoeuvre has been partitioned into three main phases based on the range of operation, plus a collision-avoidance manoeuvre to be used in event of a fault. Each has its own associated MPC controller. Linear time-varying models are used to enable trajectory predictions in elliptical orbits, whilst a variable prediction horizon is used to achieve finite-time completion of manoeuvres, and a 1-norm cost on velocity change minimises propellant consumption. Constraints are imposed to ensure that trajectories do not collide with the target. A key feature of the design is the implementation of non-convex constraints as switched convex constraints, enabling the use of convex linear and quadratic programming. The system is implemented using commercial-off-the-shelf tools with deployment using automatic code generation in mind, and validated by closed-loop simulation. A significant reduction in total propellant consumption in comparison with a baseline benchmark solution is observed

Certification of a class of industrial predictive controllers without terminal conditions

Three decades have passed encompassing a flurry of research and commercial activities in model predictive control (MPC). However, the massive strides made by the academic community in guaranteeing stability through a state- space framework have not always been directly applicable in an industrial setting. This paper is concerned with a priori and/or a posteriori certification of persistent feasibility, boundedness of industrial MPC controllers (i) based on input-output formu- lation (ii) using shorter control than prediction horizon (iii) and without terminal conditions.This work has been supported by FDOC, UGent

Photogrammetry and ballistic analysis of a high-flying projectile in the STS-124 space shuttle launch

A method combining photogrammetry with ballistic analysis is demonstrated to identify flying debris in a rocket launch environment. Debris traveling near the STS-124 Space Shuttle was captured on cameras viewing the launch pad within the first few seconds after launch. One particular piece of debris caught the attention of investigators studying the release of flame trench fire bricks because its high trajectory could indicate a flight risk to the Space Shuttle. Digitized images from two pad perimeter high-speed 16-mm film cameras were processed using photogrammetry software based on a multi-parameter optimization technique. Reference points in the image were found from 3D CAD models of the launch pad and from surveyed points on the pad. The three-dimensional reference points were matched to the equivalent two-dimensional camera projections by optimizing the camera model parameters using a gradient search optimization technique. Using this method of solving the triangulation problem, the xyz position of the object's path relative to the reference point coordinate system was found for every set of synchronized images. This trajectory was then compared to a predicted trajectory while performing regression analysis on the ballistic coefficient and other parameters. This identified, with a high degree of confidence, the object's material density and thus its probable origin within the launch pad environment. Future extensions of this methodology may make it possible to diagnose the underlying causes of debris-releasing events in near-real time, thus improving flight safety.Comment: 26 pages, 11 figures, 3 table

Autocalibration with the Minimum Number of Cameras with Known Pixel Shape

In 3D reconstruction, the recovery of the calibration parameters of the cameras is paramount since it provides metric information about the observed scene, e.g., measures of angles and ratios of distances. Autocalibration enables the estimation of the camera parameters without using a calibration device, but by enforcing simple constraints on the camera parameters. In the absence of information about the internal camera parameters such as the focal length and the principal point, the knowledge of the camera pixel shape is usually the only available constraint. Given a projective reconstruction of a rigid scene, we address the problem of the autocalibration of a minimal set of cameras with known pixel shape and otherwise arbitrarily varying intrinsic and extrinsic parameters. We propose an algorithm that only requires 5 cameras (the theoretical minimum), thus halving the number of cameras required by previous algorithms based on the same constraint. To this purpose, we introduce as our basic geometric tool the six-line conic variety (SLCV), consisting in the set of planes intersecting six given lines of 3D space in points of a conic. We show that the set of solutions of the Euclidean upgrading problem for three cameras with known pixel shape can be parameterized in a computationally efficient way. This parameterization is then used to solve autocalibration from five or more cameras, reducing the three-dimensional search space to a two-dimensional one. We provide experiments with real images showing the good performance of the technique.Comment: 19 pages, 14 figures, 7 tables, J. Math. Imaging Vi

Proceedings of the 16th Annual Meeting of the Society for Pediatric Dermatology

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75156/1/j.1525-1470.1992.tb00329.x.pd

Some Bionomics of Alphelinus Semiflavus (Howard) : Chalcid Parasite of Aphids

Author Institution: Bureau of Plant Industry, Pennsylvania Department of Agricultur