Modeling and simulation of a Stewart platform type parallel structure robot

The kinematics and dynamics of a Stewart Platform type parallel structure robot (NASA's Dynamic Docking Test System) were modeled using the method of kinematic influence coefficients (KIC) and isomorphic transformations of system dependence from one set of generalized coordinates to another. By specifying the end-effector (platform) time trajectory, the required generalized input forces which would theoretically yield the desired motion were determined. It was found that the relationship between the platform motion and the actuators motion was nonlinear. In addition, the contribution to the total generalized forces, required at the actuators, from the acceleration related terms were found to be more significant than the velocity related terms. Hence, the curve representing the total required actuator force generally resembled the curve for the acceleration related force. Another observation revealed that the acceleration related effective inertia matrix I sub dd had the tendency to decouple, with the elements on the main diagonal of I sub dd being larger than the off-diagonal elements, while the velocity related inertia power array P sub ddd did not show such tendency. This tendency results in the acceleration related force curve of a given actuator resembling the acceleration profile of that particular actuator. Furthermore, it was indicated that the effective inertia matrix for the legs is more decoupled than that for the platform. These observations provide essential information for further research to develop an effective control strategy for real-time control of the Dynamic Docking Test System

Expanding the therapeutic repertoire of epidermal growth factor receptor blockade: radiosensitization

Expression of epidermal growth factor receptor (EGFR) has been associated with radioresistance in cancer. Moreover, tumour cell recovery after irradiation paradoxically occurs, in part, as a result of activation of EGFR signalling by such treatment. A recent article by Huang, Li, Armstrong and Harari provides strong rationale for considering the anti-EGFR agent ZD1839 ('Iressa') as a radiosensitizing strategy. With the use of several in vitro and xenograft models of human squamous cell head and neck carcinoma, ZD1939 was shown to markedly improve radiotherapeutic response, with superior tumour inhibition and delayed tumour regrowth. Mechanisms underlying this effect included anti-proliferative and pro-apoptotic activity, with significant perturbation of tumour angiogenesis

Designing the Future of Amateur Astronomy: 3D Printed Telescopes

This research delves into the symbiotic relationship between engineering and astronomy through the reengineering of telescopes, emphasizing user-friendly design and cost-effectiveness. Focused on a 8-inch primary mirror and a 1.75-inch secondary mirror, our objective is to streamline the telescope\u27s functionality for the benefit of engineering and astronomy students. Employing a systematic engineering design process, we are currently designing the telescope to be 3D printed with PLA filament, eventually culminating in a collapsible telescope structure. It will be supported by aluminum extrusion and secured with hexagonal endcaps. This design ensures easy handling and facilitates cost-effective production, with spare parts readily reproducible. The outcome integrates principles from astronomy, physics, and engineering, serving as an innovative educational tool and creates more accessibility for students outside of the field who are financially disadvantaged. By combining accessibility, performance, and affordability, our telescope design aims to enhance the interdisciplinary collaboration between these fields while providing an exemplary model for cost-effective engineering projects for students outside of the university

Strategic Habitat Conservation for Declining Grassland Wildlife Populations in the Oaks and Prairies Joint Venture

Degradation and conversion of functioning grassland ecosystems in North America has driven significant declines in grassland wildlife populations across multiple taxa. In an effort to address declines in the grasslands of Oklahoma and Texas, a number of governmental agencies and Non-Governmental Organizations have partnered to form the Oaks and Prairies Joint Venture (OPJV) to more strategically and collaboratively deliver conservation actions in this region. With northern bobwhite (Colinus virginianus) as the flagship species, OPJV has worked to implement a fully integrated Strategic Habitat Conservation framework that works at multiple scales to conduct biological planning, landscape conservation design, habitat tracking and population monitoring in support of conservation efforts aimed at restoring not just northern bobwhite, but a variety of bird and pollinator species that depend on healthy grasslands. The signature conservation delivery program of this effort was the Grassland Restoration Incentive Program (GRIP) which has improved habitat for grassland wildlife on over 24,300 hectares of working lands in focus areas throughout the OPJV geography since it was created in 2013. The Grassland Restoration Incentive Program was accompanied by a full complement of conservation delivery programs that support prescribed burning associations and other landowner cooperatives, utilize market-based conservation delivery strategies, and implement strategic outreach and communications. The conservation efforts were supported by over 4,500 point counts annually in National Bobwhite Conservation Initiative Coordination Implementation Program focal areas as well as 7 focal regions, each comprising clusters of 2-8 counties. Combining the efforts of multiple partners ties the range-wide population and habitat objectives with on-the-ground conservation actions for quail, other grassland birds, butterflies, and grassland pollinators

IT Investment Strategy And IT Infrastructure Services

Organizations invest in information technology infrastructure for a variety of reasons.  One dimension describing the investment strategy is the intention of achieving cost savings versus the intention to remain flexible and responsive to the marketplace.  Of interest is the relationship between this cost-flexibility dimension and the extent to which services are provided as part of the firmwide infrastructure.  A survey of CIOs reveals that organizations emphasizing cost tend to have less investment in firmwide infrastructure across a breadth of service types than those promoting flexibility.  This implies that organizations pursuing a flexible strategy will provide a broader base of services that are common to all groups within the organization.  Firms using a cost-based strategy tend to provide less infrastructure leaving many of the services incomplete or up to individual business units within the organization

Companion animals and child/adolescent development: a systematic review of the evidence

Childhood and adolescence are important developmental phases which influence health and well-being across the life span. Social relationships are fundamental to child and adolescent development; yet studies have been limited to children’s relationships with other humans. This paper provides an evidence review for the potential associations between pet ownership and emotional; behavioural; cognitive; educational and social developmental outcomes. As the field is in the early stages; a broad set of inclusion criteria was applied. A systematic search of databases and grey literature sources found twenty-two studies meeting selection criteria. The review found evidence for an association between pet ownership and a wide range of emotional health benefits from childhood pet ownership; particularly for self-esteem and loneliness. The findings regarding childhood anxiety and depression were inconclusive. Studies also showed evidence of an association between pet ownership and educational and cognitive benefits; for example, in perspective-taking abilities and intellectual development. Evidence on behavioural development was unclear due to a lack of high quality research. Studies on pet ownership and social development provided evidence for an association with increased social competence; social networks; social interaction and social play behaviour. Overall, pet ownership and the significance of children’s bonds with companion animals have been underexplored; there is a shortage of high quality and longitudinal studies in all outcomes. Prospective studies that control for a wide range of confounders are required

The friction reducing effect of square-shaped surface textures under lubricated line-contacts - an experimental study

Surface texturing has been shown to be an effective modification approach for improving tribological performance. This study examined the friction reduction effect generated by square dimples of different sizes and geometries. Dimples were fabricated on the surface of ASP2023 steel plates using femtosecond laser-assisted surface texturing techniques, and reciprocating sliding line contact tests were carried out on a Plint TE77 tribometer using a smooth 52100 bearing steel roller and textured ASP2023 steel plates. The tribological characterization of the friction properties indicated that the textured samples had significantly lowered the friction coefficient in both boundary (15% improvement) and mixed lubrication regimes (13% improvement). Moreover, the high data sampling rate results indicated that the dimples work as lubricant reservoirs in the boundary lubrication regim