821 research outputs found
Program test objectives milestone 3
The following conclusions have been developed relative to propulsion system technology adequacy for efficient development and operation of recoverable and expendable launch vehicles (RLV and ELV) and the benefits which the integrated propulsion technology demonstrator will provide for enhancing technology: (1) Technology improvements relative to propulsion system design and operation can reduce program cost. Many features or improvement needs to enhance operability, reduce cost, and improve payload are identified. (2) The Integrated Propulsion Technology Demonstrator (IPTD) Program provides a means of resolving the majority of issues associated with improvement needs. (3) The IPTD will evaluate complex integration of vehicle and facility functions in fluid management and propulsion control systems, and provides an environment for validating improved mechanical and electrical components. (4) The IPTD provides a mechanism for investigating operational issues focusing on reducing manpower and time to perform various functions at the launch site. These efforts include model development, collection of data to validate subject models, and ultimate development of complex time line models. (5) The IPTD provides an engine test bed for tri/bi-propellant engine development firings which is representative of the actual vehicle environment. (6) The IPTD provides for only a limited multiengine configuration integration environment for RLV. Multiengine efforts may be simulated for a number of subsystems and a number of subsystems are relatively independent of the multiengine influences
Lightweight, low compression aircraft diesel engine
The feasibility of converting a spark ignition aircraft engine to the diesel cycle was investigated. Procedures necessary for converting a single cylinder GTS10-520 are described as well as a single cylinder diesel engine test program. The modification of the engine for the hot port cooling concept is discussed. A digital computer graphics simulation of a twin engine aircraft incorporating the diesel engine and Hot Fort concept is presented showing some potential gains in aircraft performance. Sample results of the computer program used in the simulation are included
Tracking the global dispersal of a cosmopolitan insect pest, the peach potato aphid
<p>Abstract</p> <p>Background</p> <p>Global commerce and human transportation are responsible for the range expansion of various insect pests such as the plant sucking aphids. High resolution DNA markers provide the opportunity to examine the genetic structure of aphid populations, identify aphid genotypes and infer their evolutionary history and routes of expansion which is of value in developing management strategies. One of the most widespread aphid species is the peach-potato aphid <it>Myzus persicae</it>, which is considered as a serious pest on various crops in many parts of the world. The present study examined the genetic variation of this aphid at a world scale and then related this to distribution patterns. In particular, 197 aphid parthenogenetic lineages from around the world were analysed with six microsatellite loci.</p> <p>Results</p> <p>Bayesian clustering and admixture analysis split the aphid genotypes into three genetic clusters: European <it>M. persicae persicae</it>, New Zealand <it>M. persicae persicae </it>and Global <it>M. persicae nicotianae</it>. This partition was supported by <it>F</it><sub>ST </sub>and genetic distance analyses. The results showed two further points, a possible connection between genotypes found in the UK and New Zealand and globalization of <it>nicotianae </it>associated with colonisation of regions where tobacco is not cultivated. In addition, we report the presence of geographically widespread clones and for the first time the presence of a <it>nicotianae </it>genotype in the Old and New World. Lastly, heterozygote deficiency was detected in some sexual and asexual populations.</p> <p>Conclusion</p> <p>The study revealed important genetic variation among the aphid populations we examined and this was partitioned according to region and host-plant. Clonal selection and gene flow between sexual and asexual lineages are important factors shaping the genetic structure of the aphid populations. In addition, the results reflected the globalization of two subspecies of <it>M. persicae </it>with successful clones being spread at various scales throughout the world. A subspecies appears to result from direct selection on tobacco plants. This information highlights the ultimate ability of a polyphagous aphid species to generate and maintain ecologically successful gene combinations through clonal propagation and the role of human transportation and global commerce for expanding their range.</p
Deep brain stimulation can suppress pathological synchronisation in parkinsonian patients
Background Although deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a highly effective therapeutic intervention in severe Parkinson's disease, its mechanism of action remains unclear. One possibility is that DBS suppresses local pathologically synchronised oscillatory activity.Methods To explore this, the authors recorded from DBS electrodes implanted in the STN of 16 patients with Parkinson's disease during simultaneous stimulation (pulse width 60 mu s; frequency 130 Hz) of the same target using a specially designed amplifier. The authors analysed data from 25 sides.Results The authors found that DBS progressively suppressed peaks in local field potential activity at frequencies between 11 and 30 Hz as voltage was increased beyond a stimulation threshold of 1.5 V. Median peak power had fallen to 54% of baseline values by a stimulation intensity of 3.0 V.Conclusion The findings suggest that DBS can suppress pathological 11-30 Hz activity in the vicinity of stimulation in patients with Parkinson's disease. This suppression occurs at stimulation voltages that are clinically effective
An applied ecology of fear framework: linking theory to conservation practice
Research on the ecology of fear has highlighted the importance of perceived risk from predators and humans in shaping animal behavior and physiology, with potential demographic and ecosystem-wide consequences. Despite recent conceptual advances and potential management implications of the ecology of fear, theory and conservation practices have rarely been linked. Many challenges in animal conservation may be alleviated by actively harnessing or compensating for risk perception and risk avoidance behavior in wild animal populations. Integration of the ecology of fear into conservation and management practice can contribute to the recovery of threatened populations, human–wildlife conflict mitigation, invasive species management, maintenance of sustainable harvest and species reintroduction plans. Here, we present an applied framework that links conservation interventions to desired outcomes by manipulating ecology of fear dynamics. We discuss how to reduce or amplify fear in wild animals by manipulating habitat structure, sensory stimuli, animal experience (previous exposure to risk) and food safety trade-offs to achieve management objectives. Changing the optimal decision-making of individuals in managed populations can then further conservation goals by shaping the spatiotemporal distribution of animals, changing predation rates and altering risk effects that scale up to demographic consequences. We also outline future directions for applied research on fear ecology that will better inform conservation practices. Our framework can help scientists and practitioners anticipate and mitigate unintended consequences of management decisions, and highlight new levers for multi-species conservation strategies that promote human–wildlife coexistence
The global development project contested: the local politics of the PRSP process in Malawi
Development, in an age of globalizations, has indeed become a global project. However, this project remains contested and contestable. While much attention has been given to this contestation at a macro-policy level, the dynamics of such contestations on the ground remain less studied. Noting that development projects, policies and programs are themselves products of power relations and social struggles, this paper focuses on the dynamics of these relations and struggles in relation to the dissemination of the global development project in Malawi. Drawing from the experiences and fractious journey from 2000 to 2006 of the broad-based civil society network involved in Malawi’s ongoing PRSP process, the paper shows how local actors draw creatively on globalized discourses of participation and representation to contest and confound the objectives of the elites, thereby complicating the channels through which the global development project is promulgated
Infrequent Detection of KI, WU and MC Polyomaviruses in Immunosuppressed Individuals with or without Progressive Multifocal Leukoencephalopathy
Conflicting prevalence of newly identified KI(KIPyV), WU(WUPyV) and Merkel Cell Carcinoma(MCPyV) polyomaviruses have been reported in progressive multifocal leukoencephalopathy(PML) patient samples, ranging from 0 to 14.3%. We analyzed the prevalence of these polyomaviruses in cerebrospinal fluid(CSF), peripheral blood mononuclear cells(PBMC), and bone marrow samples from PML patients, immunosuppressed individuals with or without HIV, and multiple sclerosis(MS) patients. Distinct PCR tests for KIPyV, WUPyV and MCPyV DNA performed in two independent laboratories detected low levels of MCPyV DNA only in 1/269 samples. The infrequent detections of these viruses in multiple samples from immunosuppressed individuals including those with PML suggest that their reactivation mechanisms may be different from that of JC polyomavirus (JCPyV) and that they do not play a role in the pathogenesis of PML
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Public service markets: their economics, institutional oversight and regulation
Public services in the UK have been transformed over the past 25 years with the introduction of market oriented solutions into their provision. This has been characterised by a shift away from state provision to independent providers, and by the introduction of competition and choice. This shift was partly ideologically motivated and partly driven by budget cutting considerations following the financial crisis. As such it has been lacking a comprehensive economic justification or method of analysis. It is now commonly accepted that the language of economic markets is essential to frame arguments about how effectively public services are achieving their intended outcomes.
Using market language and concepts may not always be comfortable for those from a traditional policy-making background. It can nevertheless be very useful when designing investigations into the effectiveness and value for money in the mechanisms of delivery of such services, whenever these services entail a degree of user choice as is currently the case in large parts of health, social care and education (referred to as competition in the market). Our paper wants to provide a conceptual basis on the way of thinking in these terms. We provide a description of the current state and then comment on the desirability of this quasi market approach. Uniquely in the literature, we analyse the expected and desired developments by distinguishing between choice and compulsory merit goods.
In choice merit goods markets many users are unable to choose effectively because of the existence of a number of demand side or supply side market failures. Moreover, conflicts may exist between how service users actually make choices, and policy objectives such as universality or equity which may not be achieved simply by ‘leaving it to the market’.
The users of compulsory merit goods are typically a minority and unable to internalise the full social benefits of their actions; hence it may be welfare-enhancing for society to coerce them ‘consume’ these services. As choice cannot be an objective, the commissioning (competition for the market) or direct provision by the state of such goods may meet public policy objectives more effectively than the market mechanism alone.
Building on these foundations the paper discusses when public service markets are likely to be an effective method of achieving public policy objectives, and when they may not be. Our paper analyses the implications for the institutional and legal framework, funding oversight and regulation of public service markets as a result of their transformation into quasi-markets. The paper concludes with some suggestions for those charged with overseeing public service markets in practice based on this analysis
Newly described human polyomaviruses Merkel Cell, KI and WU are present in urban sewage and may represent potential environmental contaminants
Recently, three new polyomaviruses (KI, WU and Merkel cell polyomavirus) have been reported to infect humans. It has also been suggested that lymphotropic polyomavirus, a virus of simian origin, infects humans. KI and WU polyomaviruses have been detected mainly in specimens from the respiratory tract while Merkel cell polyomavirus has been described in a very high percentage of Merkel cell carcinomas. The distribution, excretion level and transmission routes of these viruses remain unknown
Is there an app for that? A case study of the potentials and limitations of the participatory turn and networked publics for classical music audience engagement
The participatory turn, fuelled by discourses and rhetoric regarding social media, and in the
aftermath of the dot.com crash of the early 2000s, enrols to some extent an idea of being
able to deploy networks to achieve institutional aims. The arts and cultural sector in the UK,
in the face of funding cuts, has been keen to engage with such ideas in order to demonstrate
value for money; by improving the efficiency of their operations, improving their respective
audience experience and ultimately increasing audience size and engagement. Drawing on a
case study compiled via a collaborative research project with a UK-based symphony
orchestra (UKSO) we interrogate the potentials of social media engagement for audience
development work through participatory media and networked publics. We argue that the
literature related to mobile phones and applications (‘apps’) has focused primarily on
marketing for engagement where institutional contexts are concerned. In contrast, our
analysis elucidates the broader potentials and limitations of social-media-enabled apps for
audience development and engagement beyond a marketing paradigm. In the case of UKSO,
it appears that the technologically deterministic discourses often associated with institutional
enrolment of participatory media and networked publics may not necessarily apply due to
classical music culture. More generally, this work raises the contradictory nature of
networked publics and argues for increased critical engagement with the concept
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