1,386 research outputs found
Conceptual mechanization studies for a horizon definition spacecraft attitude control subsystem, phase A, part II, 10 October 1966 - 29 May 1967
Attitude control subsystem for spin stabilized spacecraft for mapping earths infrared horizon radiance profiles in 15 micron carbon dioxide absorption ban
Pharmacology of DB844, an orally active aza analogue of pafuramidine, in a monkey model of second stage human African trypanosomiasis
Novel drugs to treat human African trypanosomiasis (HAT) are still urgently needed despite the recent addition of nifurtimox-eflornithine combination therapy (NECT) to WHO Model Lists of Essential Medicines against second stage HAT, where parasites have invaded the central nervous system (CNS). The pharmacology of a potential orally available lead compound, N-methoxy-6-{5-[4-(N-methoxyamidino) phenyl]-furan-2-yl}-nicotinamidine (DB844), was evaluated in a vervet monkey model of second stage HAT, following promising results in mice. DB844 was administered orally to vervet monkeys, beginning 28 days post infection (DPI) with Trypanosoma brucei rhodesiense KETRI 2537. DB844 was absorbed and converted to the active metabolite 6-[5-(4-phenylamidinophenyl)-furanyl-2-yl]-nicotinamide (DB820), exhibiting plasma C(max) values of 430 and 190 nM for DB844 and DB820, respectively, after the 14th dose at 6 mg/kg qd. A 100-fold reduction in blood trypanosome counts was observed within 24 h of the third dose and, at the end of treatment evaluation performed four days post the last drug dose, trypanosomes were not detected in the blood or cerebrospinal fluid of any monkey. However, some animals relapsed during the 300 days of post treatment monitoring, resulting in a cure rate of 3/8 (37.5%) and 3/7 (42.9%) for the 5 mg/kg×10 days and the 6 mg/kg×14 days dose regimens respectively. These DB844 efficacy data were an improvement compared with pentamidine and pafuramidine both of which were previously shown to be non-curative in this model of CNS stage HAT. These data show that synthesis of novel diamidines with improved activity against CNS-stage HAT was possible
Discrete Cylindrical Vector Beam Generation from an Array of Optical Fibers
A novel method is presented for the beam shaping of far field intensity
distributions of coherently combined fiber arrays. The fibers are arranged
uniformly on the perimeter of a circle, and the linearly polarized beams of
equal shape are superimposed such that the far field pattern represents an
effective radially polarized vector beam, or discrete cylindrical vector (DCV)
beam. The DCV beam is produced by three or more beams that each individually
have a varying polarization vector. The beams are appropriately distributed in
the near field such that the far field intensity distribution has a central
null. This result is in contrast to the situation of parallel linearly
polarized beams, where the intensity peaks on axis
Integrated engineering environments for large complex products
An introduction is given to the Engineering Design Centre at the University of Newcastle upon Tyne, along with a brief explanation of the main focus towards large made-to-order products. Three key areas of research at the Centre, which have evolved as a result of collaboration with industrial partners from various sectors of industry, are identified as (1) decision support and optimisation, (2) design for lifecycle, and (3) design integration and co-ordination. A summary of the unique features of large made-to-order products is then presented, which includes the need for integration and co-ordination technologies. Thus, an overview of the existing integration and co-ordination technologies is presented followed by a brief explanation of research in these areas at the Engineering Design Centre. A more detailed description is then presented regarding the co-ordination aspect of research being conducted at the Engineering Design Centre, in collaboration with the CAD Centre at the University of Strathclyde. Concurrent Engineering is acknowledged as a strategy for improving the design process, however design coordination is viewed as a principal requirement for its successful implementation. That is, design co-ordination is proposed as being the key to a mechanism that is able to maximise and realise any potential opportunity of concurrency. Thus, an agentoriented approach to co-ordination is presented, which incorporates various types of agents responsible for managing their respective activities. The co-ordinated approach, which is implemented within the Design Co-ordination System, includes features such as resource management and monitoring, dynamic scheduling, activity direction, task enactment, and information management. An application of the Design Co-ordination System, in conjunction with a robust concept exploration tool, shows that the computational design analysis involved in evaluating many design concepts can be performed more efficiently through a co-ordinated approach
Generation of a wave packet tailored to efficient free space excitation of a single atom
We demonstrate the generation of an optical dipole wave suitable for the
process of efficiently coupling single quanta of light and matter in free
space. We employ a parabolic mirror for the conversion of a transverse beam
mode to a focused dipole wave and show the required spatial and temporal
shaping of the mode incident onto the mirror. The results include a proof of
principle correction of the parabolic mirror's aberrations. For the application
of exciting an atom with a single photon pulse we demonstrate the creation of a
suitable temporal pulse envelope. We infer coupling strengths of 89% and
success probabilities of up to 87% for the application of exciting a single
atom for the current experimental parameters.Comment: to be published in Europ. Phys. J.
Control Law Design for Perching an Agile MAV with Articulated Wings
This paper explores the use of variable wing dihedral and variable wing twist (in conjunction
with a conventional horizontal elevator) to control an aircraft performing a perching
maneuver. A choice of controller architecture wherein the dihedral is employed in the
forward path and the elevator and twist are employed in the feedback path, is considered.
The aircraft is modeled as a multivariable linear time-varying system. A specific perching
trajectory is considered; and the open-loop aircraft is longitudinally unstable for a segment
of this perching trajectory and lateral-directionally unstable for the entire perching trajectory.
A multivariable time-varying controller is designed to efficiently stabilize the aircraft
as well as reject longitudinal-lateral-directional wind disturbances, while closely tracking
the reference perching trajectory
Efficacy of DB289 in Thai Patients with Plasmodium vivax or Acute, Uncomplicated Plasmodium falciparum Infections
BackgroundDB289 is the orally active prodrug of the diamidine DB75, which was developed for the treatment of human African trypanosomiasis MethodsWe tested the safety and efficacy of DB289 for the treatment of Plasmodium vivax and acute, uncomplicated P. falciparum infections in an open-label pilot study at the Hospital for Tropical Diseases in Bangkok. Nine patients with P. vivax infections and 23 patients with P. falciparum infections were admitted and treated with 100 mg of DB289 given orally twice a day for 5 days and were followed for 28 days. Patients with P. vivax infections were also treated with primaquine on days 10-23 ResultsAll patients cleared parasites by day 7, with a mean±SD clearance time of 43±41 h. One patient with a P. vivax infection had a recurrence of parasitemia on day 9. Of the 23 patients with P. falciparum infections, 3 had recurrences of parasitemia caused by P. vivax and 2 had recurrences of parasitemia caused by P. falciparum. In only 1 of 2 recurrences of parasitemia caused by P. falciparum were the parasites genotypically distinct from the infecting parasites the patient had at enrollment, which means there was a 96% cure rate ConclusionsDB289 is a promising new antimalarial compound that could become an important component of new antimalarial combination
Identifying Levels of Engagement in Local Food Systems by Generation in the State of Georgia, U.S.A.
Local food systems are an emerging way for communities to build vibrant economies, improve health outcomes, and limit their environmental impact. Studies have shown local food engagement differs significantly between generations; however, what remains unclear is how generations’ perceptions and engagement compare to each other so the agricultural community can most effectively communicate about local food systems. Leveraging audience segmentation theory from social marketing, this study sought to address how the five living generations in the United States – Generation Z, Millennials, Generation X, Baby Boomers, and The Silent Generation – perceived and engaged with local food systems. To address this question, a non-probability opt-in sampling of 863 adults in the state of Georgia was used. Each participant was asked four questions pertaining to different aspects of local food systems – the purchase of local foods from grocery stores, use of local food markets, participation in local food events, and level of engagement with local food related media. Millennials and Generation X’ers expressed significantly higher levels of engagement with local food systems when compared to Baby Boomers and The Silent Generation, this was not observed between Generation Z and any other group. While Millennials and X’ers engaged at higher levels, significant opportunities remain for engagement through generation-specific media to turn the universal tepid interest in local food systems into action. Future research should seek to identify the relationship between generational media preferences and how effective they are at transforming interest in local food systems into action
An Appreciative Approach to Assessing Extension Professionals’ Perceptions of Evaluation
Generating timely, honest, and useful feedback is the cornerstone of all extension program evaluation. However, historical evaluation practices, especially in the international agricultural extension context, have relied on models that emphasize external criticism. One model of evaluation that has the potential to shift the focus toward a more collaborative model of evaluation is that of appreciative evaluation. Appreciative evaluation strives towards building on existing strengths rather than criticizing weaknesses with an emphasis on identifying what an organization does well. This research note reviews the results of a recent survey given to a group of extension professionals within a large land-grant institution to examine how extension professionals view the role of evaluation within their programming from an appreciative perspective. Respondents (n = 204) expressed great professional satisfaction in their work delivering programs and a sense of self-worth stemming from the impact they have in their respective communities. Evaluation tools and techniques were enabling forces as they allowed respondents to gather timely data and make adjustments to programs in ways that were reflective of community needs. When asked to identify any structural components of the extension system that improve evaluation practices and procedures, respondents emphasized the importance of both formal and non-formal training opportunities, the development of modular evaluation tools, and collaboration both within extension and their respective community(ies). The results indicated appreciative inquiry methods have the potential to provide valuable feedback about existing programming
Easing into the Academy: Using Technology to Foster Cross-Institutional Critical Friendships
This article addresses the ways in which early career teacher educators can support each other as they enter the academic community. By utilizing technology as an instrument to engage in a cross-country critical friendship, the authors were able to engage in a dialogue that grew out of mutual interests and concerns. Through critical reflection, they were able to address the question: How can we, two early-career teacher educators, push ourselves and one another to more critically examine our teaching practices? In doing so, each “new educator” grew more confident in claiming one\u27s voice as a sustainable critical friendship emerged
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