6,649 research outputs found

    Interaction and observation: categorical semantics of reactive systems trough dialgebras

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    We use dialgebras, generalising both algebras and coalgebras, as a complement of the standard coalgebraic framework, aimed at describing the semantics of an interactive system by the means of reaction rules. In this model, interaction is built-in, and semantic equivalence arises from it, instead of being determined by a (possibly difficult) understanding of the side effects of a component in isolation. Behavioural equivalence in dialgebras is determined by how a given process interacts with the others, and the obtained observations. We develop a technique to inter-define categories of dialgebras of different functors, that in particular permits us to compare a standard coalgebraic semantics and its dialgebraic counterpart. We exemplify the framework using the CCS and the pi-calculus. Remarkably, the dialgebra giving semantics to the pi-calculus does not require the use of presheaf categories

    Innovating access to the nurse-led hepatitis C clinic using co-production

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    Background Many reasons for missed appointments are given by people who inject drugs and it is suggested that one solution cannot solve this complex issue (Poll et al., 2017). Increasingly, nurses and other health professionals are expected to actively involve patients and service users in developing innovative, effective and accessible services. This project used co-production as the approach to address this challenge. Aims This paper describes how a co-production method was used to develop accessible nurse-led hepatitis C virus services for people who inject drugs. Methods Using research evidence from a study conducted by the lead author as a starting point, a series of co-production workshops were run using creative co-design methods to identify the barriers to engagement with clinics. Potential solutions were then co-produced. Results The solutions included myth-busting posters, peer-support, a mobile clinic van and the offer of incentives and enablers (travel costs or a reward for attendance). Conclusions The service-development project illustrates how, with the right methods, it is possible to successfully engage with hard-to-access groups to co-produce innovative solutions for an important clinical challenge

    Rassenonderzoek witte asperge seizoen 2001-2002

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    In 2000 zijn twee nieuwe rassenproeven witte asperge aangelegd in Meterik, Nederland (PPO) en in Geel, België (PDLT). Er zijn 10 dezelfde rassen aangeplant op beide plaatsen. De rassen zijn gezaaid bij plantenkwekerij de Kemp in Meterik in 1999. Het sortiment bestaat uit de Hollandse rassen Backlim, Gijnlim, Thielim, Grolim afkomstig van Asparagus BV te Horst en de Duitse rassen Eposs, Ramada, Ramos, Ravel , Rally (96013) en Rapsody (96071) afkomstig van SWD Saatsucht. De Nederlandse rassen worden verkocht door Nunhem en de Duitse door Royal Sluis

    Acclimation to a dynamic irradiance regime changes excessive irradiance sensitivity of Emiliania huxleyi and Thalassiosira weissflogii

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    Effects of fluctuating irradiance regimes on excessive photosynthetically active radiation (PAR) and ultraviolet (UV) radiation sensitivity were assessed for Emiliania huxleyi (Lohman) and Thalassiosira weissflogii (Grunow) Fryxell and Hasle. Cultures acclimated to low irradiance were subjected to two irradiance regimes of equal daily dose: dynamic irradiance simulating vertical mixing within the water column and constant irradiance. For each regime two irradiance levels were studied. Growth was monitored for 3 d, after which pigment composition was determined. Next, excessive PAR and UV sensitivity was measured by studying viability loss during 4-h exposure to simulated surface irradiance (SSI). Furthermore, the effects of inhibition of D1 reaction center protein turnover were investigated by incubating samples with lincomycin prior to exposure. Dynamic irradiance reduced growth rates of both species as compared to constant irradiance. Pools of light-harvesting pigments increased in dynamic irradiance, whereas the protective pigment pools decreased compared to constant irradiance. Excessive irradiance sensitivity was enhanced in cells grown in fluctuating irradiance. Furthermore, viability loss was most pronounced in UV treatments combined with lincomycin. E. huxleyi was more sensitive to excessive irradiance than T. weissflogii, which coincided with a lower ratio between protective and light-harvesting pigments in the former species. Irradiance modulation by deep vertical mixing influences growth, pigment composition, and excessive PAR and UV sensitivity within days

    An overview of the implementation of Economic Value Added (EVAℱ) performance measures in South Africa

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    Although Economic Value Added (EVA™) might improve themeasurement of organisations’ performance, it seems not to be usedwidely in South Africa. The need to measure financial performanceand the different metrics that can be used should be investigatedto establish the best measure for each sector. The purpose of thereported study was to determine the extent to which EVA™ is usedby South African organisations. Furthermore, this investigationfocused on methods used by these organisations to calculate EVA™and aimed to determine the South African business sectors in whichit is most likely to be implemented. A focus group discussion wasconducted with financial experts, which included consultants,analysts and statisticians, to discuss EVA™ and challenges relating toits implementation. It was established that South African companieswill benefit from using EVA™ in conjunction with other metrics.Management needs to understand its own organisation to be able toimplement the most appropriate performance metric applicable tothe organisation. It is recommended that companies do a thoroughinternal analysis of their organisations to assist them in making aninformed decision regarding the appropriate performance metric,which includes EVA™

    Taxon‐specific dark survival of diatoms and flagellates affects Arctic phytoplankton composition during the polar night and early spring

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    Effects of prolonged darkness on Arctic phytoplankton composition were investigated with lab experiments and a pigment time series in Kongsfjorden, Spitsbergen (78°55â€ČN). Chlorophyll a (Chl a), pigment composition, particulate organic carbon, cell numbers, and photosynthetic characteristics were studied in Arctic diatoms (Thalassiosira antarctica, Thalassiosira nordenskioeldii) and flagellates (Rhodomonas sp., Micromonas sp.) during 8 weeks of darkness and subsequent recovery in irradiance. Loss of photosynthetic functionality after 2 weeks of darkness was reversible in all species when returned to irradiance. Diatoms were more resistant to prolonged darkness (> 2 weeks) compared to the flagellates, with lower decline rates of Chl a and maximum quantum yield of PSII. T. nordenskioeldii showed rapid growth during recovery throughout 8 weeks of dark incubation, whereas recovery of flagellates diminished within 4 weeks. Ratios of taxonomic marker pigments relative to Chl a of all species showed limited variation during 8 weeks of dark incubation. The experimentally observed enhanced dark survival of diatoms was in agreement with pigment observations during four polar nights (2013–2017) in Kongsfjorden, which showed increased relative diatom abundance during declining biomass (down to 0.02 mg Chl a m−3). Therefore, a period of prolonged darkness gives Arctic diatoms a head start during the early stages of the spring bloom. The taxon‐specific survival traits can influence the geographical distribution of diatoms and flagellates within the polar oceans and their phenology. Furthermore, the persistence of Chl a of nonviable phytoplankton during darkness might influence biomass estimates during the polar night

    Forest investigations by polarimetric AIRSAR data in the Harz mountains

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    The Harz Mountains in the North of Germany have been a study site for several remote sensing investigations since 1985, as the mountainous area is one of the forest regions in Germany heavily affected by forest decline, especially in the high altitudes above 800 m. In a research program at the University of Berlin, methods are developed for improving remote sensing assessment of forest structure and forest state by additional GIS information, using several datasets for establishing a forest information system. The Harz has been defined as a test site for the SIR-C/X-SAR mission which is going to deliver multifrequency and multipolarizational SAR data from orbit. In a pilot project let by DLR-DFD, these data are to be investigated for forestry and ecology purposes. In preparing a flight campaign to the SIR-C / X-SAR mission, 'MAC EUROPE 1991', performed by NASA/JPL, an area of about 12 km in the Northern Harz was covered with multipolarizational AIRSAR data in the C-, L- and P-band, including the Brocken, the highest mountain of the Harz, with an altitude of 1142 m. The multiparameter AIRSAR data are investigated for their information content on the forest state, regarding the following questions: (1) information on forest stand parameters like forest types, age classes and crown density, especially for the separation of deciduous and coniferous forest; (2) information on the storm damages (since 1972) and the status of regeneration; (3) information on the status of forest destruction because of forest decline; and (4) influence of topography, local incidence angle and soil moisture on the SAR data. Within the project various methods and tools have been developed for the investigation of multipolarimetric radar backscatter responses and for discrimination purposes, in order to use the multipolarization information of the compressed Stokes matrix delivered by JPL
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