105 research outputs found
Evolutionary and demographic processes in the invasive weed Microstegium vimineum
No full textMicrostegium vimineum (Trin.) A. Camus (stiltgrass) is considered among the most invasive plants in the eastern United States. There has been considerable study of this species’ ecology and management though far less attention has been paid to its molecular ecology and the evolutionary processes which may influence its invasion success. Here, I describe a newly developed molecular marker system (microsatellite) which I used to examine M. vimineum’s genetic population structure and diversity in both its native and introduced ranges. I found clear signals that M. vimineum’s mating system is the most important determinant of the species’ population structure and variability. The invasive range had lower genetic diversity overall, probably due to founder effects. Also, population and regional genetic differentiation appeared to be ‘in process’ in the invasive range. Furthermore, M. vimineum’s mixed cleistogamous/chasmogamous mating system allowed for the near fixation of microsatellite genotypes in a given population by high rates of selfing, while still permitting the persistence of allelic diversity and generation of new genotypes at low frequency via occasional outcrossing. Thus, this mating system may confer adaptive advantage to the species as it settles upon fit genotypes in a given area while retaining evolutionary potential for range expansion into new habitats. I also attempted to discern adaptively significant phenotypes in M. vimineum through the measurement of phenological variation of plants originating from across the species’ invasive range under manipulated light treatments. Flowering time and biomass were both strongly correlated with the latitude of population origin such that populations collected from more northern latitudes flowered significantly earlier at lower biomass than populations from southern locations. This pattern suggests rapid adaptive evolution of phenology over a period of less than one hundred years, and such changes have likely promoted the northward range expansion of this species. Interestingly, barriers to gene flow, including bottlenecks and inbreeding, have apparently not forestalled adaptive processes for this plant. Based on literature review and these new data, I hypothesize that adaptive evolution of phenological traits may be widespread in many invasive plant species and an essential process during range expansion.Ph. D.Includes bibliographical referencesIncludes vitaby Ari E. Nov
The United States Botanic Garden in Washington, DC
No full textThe United States Botanic Garden (USBG) was initially established in 1820, though a tumultuous beginning did not allow it to become a permanent institution until 1850. Nevertheless, it is one of the oldest botanic gardens in North America and one of the most visited. This article provides a brief history of the USBG and an overview of its operations and collections. With its centrallocation in a major US metropolitan region and free entry to visitors, the USBG has a strong focus on visitor services, experience and education. Approaching its 200th year, the Garden is well poised to play a leading role in exciting the American public about the importance of plants to humankind
Lou Novy para (1743) de Jean-Baptiste Coye : une pièce française ou une pièce provençale ?
No full textInternational audienceWritten by the Arlesian Jean-Baptiste Coye (1711-1771) and published in 1743, the play Lou Novy para is a comedy of the kind found in French and Occitan : a young girl refuses to marry the husband her father has chosen for her, she prefers her lover. she prefers her lover. He convinces her to run away together, but the ship they are embarking on is caught in a storm on the Rhône. Faced with the two surviving lovers and at the urging of his brother, the intractable father finally gives in and the marriage is decided. The subject and its treatment are in line with contemporary French theatre practice, which the author seems to know well. There are many references to the French framework and the language contains a considerable number of francisms. This proximity to French aesthetic and linguistic models can be explained by Coye's literary ambition to place Provençal on the same level as French-language theatre.Écrite par l’Arlésien Jean-Baptiste Coye (1711-1771) et publiée en 1743, la pièce Lou Novy para se présente sous la forme d’une comédie comme on en trouve en français et en occitan : une jeune fille refuse d’épouser le mari que son père a choisi pour elle, elle préfère son amoureux. Celui-ci la convainc de fuir avec lui mais le navire sur lequel ils s’embarquent est victime d’une tempête sur le Rhône. Face aux deux amoureux rescapés et sur les instances de son frère, le père intraitable finit par céder et le mariage est décidé. Le sujet et son traitement sont conformes aux pratiques du théâtre français contemporain que l’auteur semble bien connaître. Les références au cadre français sont nombreuses et la langue recèle un nombre considérable de francismes. Cette proximité avec les modèles esthétiques et linguistiques français s’explique par l’ambition littéraire de Coye qui voit là un moyen de situer le provençal au même niveau que la création théâtrale de langue française
E-Hub - Solar Powered Electric Vehicle Charging Station: Electrical system design, Optimisation and Testing
No full textThe development in technology and increased public interest has attributed to an unprecedented growth of E-mobility in recent years. Electric vehicles (EVs) even though viewed as emission free and environmental friendly can still contribute towards indirect emissions if charged by using traditional fossil fuels. The integration of renewable energy sources is hence paramount to approach a completely carbon free future of E-mobility integration in the transportation sector. This thesis project aims at designing and implementing a photovoltaic (PV) based charging station for a fleet of ten EVs in the TU Delft campus. The complete solar powered charging station for EVs is hence called as E-Hub, which aims to facilitate the development of e-mobility in the TU Delft campus by providing charging facilities that can be scaled up along with a competitive business model. At first, the driving pattern of EV owners in the Netherlands is analysed to categorize employees and visitors. The driving pattern is used to estimate the load profile and the yearly charging demand for the EV fleet in the TU Delft campus. Calendar effects such as holidays and vacations are taken into account to accurately predict the charging demand. A thorough PV system design is carried out to meet the estimated charging demand, followed by a practical and economic feasibility study. The components required for the E-hub are listed along with an estimation of the initial investment. Later an optimisation model is used to develop power management algorithms for optimum economical performance based on the designed technical framework. Nine charging strategies are considered for both summer and winter conditions. The performance of each strategy is analysed under the estimated load profile and designed PV system. The model is also extended to explore the integration of battery systems and its effect on the technical and economical performance of the E-Hub. This battery system can hence function as a virtual power plant to supply power back to the grid in times of peak load and facilitate in stabilization of the grid. A proof of concept is then built to test the developed power management algorithms in the Electrical Sustainable Power Lab (EWI, TU Delft). The Eneco SolarEdge and Tesla Powerwall (ESTP) set-up is used to study the power flow and a system is designed to dynamically control and monitor the ESTP set-up. It was concluded that such a system is technically and economically feasible and can be implemented in the university to provide an environmentally friendly charging infrastructure to electrical vehicles.E-HubElectrical Engineering | Sustainable Energy Technolog
Influence of big data competencies and self-efficacy on detection of financial statement fraud on internal auditors in Indonesia / Novy Silvia Dewi ... [et al.]
No full textDetection of financial statement fraud is important in maintaining the integrity and reliability of a company’s financial information. Internal auditors have the responsibility to detect fraud in the company’s financial statements. This study aimed to test whether the existence of big data competencies can help internal auditors in the detection of financial statement fraud. This study also examined whether psychological factors such as self-efficacy can affect internal auditors in the detection of financial statement fraud. The research method used was the quantitative method. The research focused on internal auditors who employed in Indonesian companies. Data collection used questionnaire with 230 samples and analyzed using regression analysis using SmartPLS software. The results showed that big data competencies had a positive and significant effect on self-efficacy. The ability to analyze big data competencies is crucial role in detecting financial statement fraud, and individuals’ confidence in their skills also had a positive impact on fraud detection. Additionally, selfefficacy served as a significant mediator between big data competencies and the detection of financial statement fraud. This research has significant implications for practitioners and organizations in Indonesia in the context of developing strategies to improve the ability of internal auditors to detect fraudulent financial reports
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