Li\u27L Dan, The Drummer Boy A Civil War Story

Li\u27l Dan, The Drummer Boy: Interviews with Dr. Maya Angelou and Dr. Robin D. G. Kelley by Leah Wood Jewett Maya Angelou is a celebrated poet, writer, and educator. The author of I Know Why the Caged Bird Sings, she is a recipient of the Presidential Medal of Honor. She...

A behavioral cascade: Top-predator induced behavioral shifts in planktivorous fish and zooplankton

It is well known that the effects of direct (lethal) predator-prey interactions propagate through food webs (the trophic cascade). However, in the present study we show for the first time that, parallel to the trophic cascade, there exists a behavioral cascade in the sense that behavioral responses, induced by the nonlethal presence of a top predator, are transmitted down the food chain over more than one trophic link. By using a new method, horizontal echo sounding, in an enclosure study in a shallow lake in southern Sweden, we recorded the swimming activity and refuge use of young-of-the-year (0+) roach (Rutilus rutilus) in the presence and the absence of a caged predatory fish. By connecting the predator avoidance behavior of 0+ roach with that of zooplankton throughout summer, we show that species interactions are more dynamic than had been predicted earlier by food web theory. In our study, 0+ roach changed their behavior by becoming less active in early summer and by hiding in a refuge in late summer in the presence of a piscivore, and this caused Daphnia to spend more time feeding in the open water than when piscivores were absent. Thus, we conclude that, to explain patterns of habitat use in natural systems, it is of crucial importance that we recognize the existence of behavioral cascades

Life cycle assessment of city buses powered by electricity, hydrogenated vegetable oil or diesel

This study explores life cycle environmental impacts of city buses, depending on the: (1) degree of electrification; (2) electricity supply mix, for chargeable options; and (3) choice of diesel or hydrogenated vegetable oil (HVO), a biodiesel, for options with combustion engine. It is a case study, which uses industry data to investigate the impact on climate change, a key driver for electrification, and a wider set of impacts, for average operation in Sweden, the European Union and the United States of America. The results show that non-chargeable hybrid electric vehicles provide clear climate change mitigation potential compared to conventional buses, regardless of the available fuel being diesel or HVO. When fueling with HVO, plug-in hybrid and all-electric buses provide further benefits for grid intensities below 200 g CO₂ eq./kWh. For diesel, the all-electric option is preferable up to 750 g CO₂ eq./kWh. This is the case despite batteries and other electric powertrain parts causing an increase of CO₂ emissions from vehicle production. However, material processing to make common parts, i.e. chassis, frame and body, dominates the production load for all models. Consequently, city buses differ from passenger cars, where the battery packs play a larger role. In regard to other airborne pollutants, the all-electric bus has the best potential to reduce impacts overall, but the results depend on the amount of fossil fuels and combustion processes in the electricity production. For toxic emissions and resource use, the extraction of metals and fossil fuels calls for attention

Moving beyond traditional measures – lessons from evaluating collaborative initiatives at Lund University

Over the last decade, universities and other institutions of higher education (HEIs) worldwide have witnessed an evolution to their role relative to society – with increasing attention to external engagement and expectations on societal impact. This has fostered an upswing in activity as research and innovation funding bodies and universities alike explore new approaches to working with external engagement, and led to questions regarding how to evaluate the societal impact of these efforts. Although there are examples of national frameworks to evaluate research impact, the large majority of countries and HEIs around theworld are still experimenting with approaches to evidence and assess their pathway to societal impact. This paper aims to contribute to evolving practice in this field by presenting lessons from the evaluation of a new strategic instrument (thematic collaboration initiatives) at Lund University (LU), Sweden.The evaluation of the strategic instrument “thematic collaboration initiatives” encompassed both initiative/operational and LU leadership/strategic levels. The approach to the evaluation combined traditional measures and processes, together with new indicators and evaluation approaches. The evaluation hasresulted in a better understanding of the range of activities and outputs that one can expect from such collaborative initiatives – informing the selection of measures to include in evaluation efforts. The evaluation also provided new insights on how universities can work with and use evaluation to guide thefurther development of the university’s approach to fostering external engagement. Participatory processes and facilitated reflection were very beneficial to draw out multiple perspectives and possible implicationsfor future development of the instrument

The Application of Adaptive Linear and N on-Linear Filters to Fringe Order Identification in White-Light Interferometry Systems

Conventional optical interferometry systems driven by highly coherent light sources have a very short unambiguous operating range, a direct consequence of the flatness of the interference fringes visibility profile at the output of the system. The range can be extended by using a white-light interferometer (WU), which is driven by a low-coherence source and produces a Gaussian visibility profile with a unique maximum in correspondence of the central fringe. Due to system and/or measurement noise, however, the position of the maximum (from which an accurate measurement of the measurand - displacement, temperature, pressure, flow, etc. - can be derived) is not easily detectable, and can lead to large measurement errors. This is especially true in a multiplexing scheme, where the source power is distributed evenly among various sensors, with a corresponding drop in the overall signal-to-noise ratio. The inclusion of a signal processing scheme at the receiver end is thus a necessity. As the fringe pattern at the output of a WLI system is basically a noisy sine wave amplitude modulated by a Gaussian envelope, it can be classified as a non-stationary, narrow-band, linear but non-Gaussian signa\. So far, no attempt has been made to apply digital filtering techniques, as understood in the signal processing community, to the output signal of a WLI system. This thesis constitutes a first step in that direction. Since the only measurable information given by the system is contained in the output signal, the system is modelled as a "black box" driven by the system and measurement noise processes and containing an unknown set of parameters. Standard least squares techniques can then be applied to estimate the parameters of the model, as is usually done in the field of system identification when only noisy output measurements are available. It is shown that identification of the model parameters is equivalent to finding a set of coefficients for an inverse filter which takes the WU signal at its input and delivers the unknown noise process at the output. The non-stationarity of the signal is accounted for by allowing for time variations of the model parameters; this justifies the use of adaptive filters with time-varying coefficients. A new central fringe identification scheme is proposed, based on a modification of the standard least mean square (LMS) adaptive filtering algorithm in combination with amplitude thresholding of the fringe pattern. The new scheme is shown to offer considerable improvement in the identification rate when tested against current schemes over comparable operating ranges, while retaining the computational simplicity and operational speed of the standard LMS. Its performance is also shown to be largely independent of the step-size parameter controlling the rate of convergence and tracking in the standard LMS, which is known to be the main obstacle for a successful application of the algorithm in a practical setting. The non-Gaussianity of the signal is explored and an attempt is made to apply higher-order statistics (HOS) algorithms to central fringe identification. The effectiveness of Gaussianity tests on pilot Gaussian data is seen to depend not only on the number and length of records available but, perhaps more importantly, on the bandwidth of the process. Violation of the stationarity assumption is shown to lead to mis-classification of a seemingly non-Gaussian signal into a Gaussian one, as the visibility profile may alter the distribution of the underlying sinusoid making it appear Gaussian, even when beam diffraction and wavefront aberrations combine to produce a nonGaussian profile. HOS-based adaptive algorithms may still be of some benefit, however, if processing is confined to that region of the fringe pattern where sufficient non-Gaussianity is allowed to develop. Non-linear adaptive filters based on the Volterra theories are finally applied to compensate for possible non-linearities introduced by mismatches in optical components, chromatic aberrations, and analogue-to-digital converters. It is shown that although a Volterra filter is able to reproduce the low-amplitude distortions of the fringe pattern better than a linear filter does, the identification rate does not improve. Reasons are given for such behaviour

Tematiska samverkansinitiativ vid Lunds universitet - Resultat och reflektioner

Rapport som sammanfattar utvärderingen av den första generationen av tematiska samverkansinitiativ vid Lunds universitet 2017-2019

Effects of enrichment on simple aquatic food webs

Simple models, based on Lotka-Volterra types of interactions between predator and prey, predict that enrichment will have a destabilizing effect on populations and that equilibrium population densities will change at the top trophic level and every second level below. We experimentally tested these predictions in three aquatic food web configurations subjected to either high or low nutrient additions. The results were structured by viewing the systems as either food chains or webs and showed that trophic level biomass increased with enrichment, which contradicts food chain theory. However, within each trophic level, food web configuration affected the extent to which different functional groups responded to enrichment. By dividing trophic levels into functional groups, based on vulnerability to consumption, we were able to identify significant effects that were obscured when systems were viewed as food chains. The results support the prediction that invulnerable prey may stabilize trophic-level dynamics by replacing other, more vulnerable prey. Furthermore, the vulnerable prey, such as Daphnia and edible algae, responded as predicted by the paradox of enrichment hypothesis; that is, variability in population density increased with enrichment. Hence, by describing ecosystems as a matrix of food web interactions, and by recognizing the interplay between interspecific competition and predation, a more complete description of the ecosystem function was obtained compared to when species were placed into distinct trophic levels

Planktivory in non-indigenous fish and implications for trophic interactions in a Mediterranean shallow lake

Similar to other Mediterranean lakes, Lake Vela displays a marked dominance of alien species, but the impact of such an assemblage on the lower trophic levels of shallow eutrophic lakes has been overlooked. In this study, zooplanktivory in the omnivorous fish assemblage of Lake Vela was examined from April to October 2003 (and also in January 2004). During this period, ichthyocenosis was characterized by abundance of juvenile fish, which strongly depended on zooplankton. Adult mosquitofish (Gambusia holbrooki) and pumpkinseed (Lepomis gibbosus) foraged on the same zooplanktonic prey than juveniles, although planktivory was less important in larger fish. Using multivariate analysis, it was possible to attribute most of the variability in planktivory to resource availability, as both fish foraged on the most abundant prey in each month. Albeit this opportunistic behaviour, mosquitofish was found to be positively selective towards small-sized littoral cladocerans, while pumpkinseed displayed positive selection towards Alona and Daphnia. In the absence of more efficient planktivores, pumpkinseed is now the main planktivore in Lake Vela and the main predator of Daphnia. However, due to low densities of Daphnia during most of the study period, Daphnia was virtually absent from the diet of pumpkinseed from June to October, a period during which this benthi–planktivore foraged chiefly on less-rewarding planktonic prey (small-sized cladocerans and cyclopoid copepods). Mosquitofish was an important planktivore in littoral and structured habitats. Flexible foraging behaviour partly explains the success of these two species in Lake Vela.Acknowledgements are due to José Vingada (University of Minho, Portugal) for supplying the fishing gear apparatuses and for providing help during fieldwork. We are also thankful to Francisca F. Gouveia for her laborious collaboration in the measurement and dissection of the fish. Bruno B. Castro was supported by a PhD grant (ref.SFRH/BD/6417/2001) from Fundação para a Ciência e a Tecnologia (Portugal). Bruno B. Castro is presently hired under the programme Ciência 2008 (FCT, Portugal), co-funded by the Human Potential Operational Programme (National Strategic Reference Framework 2007–2013) and European Social Fund (EU). We also thank two anonymous referees for their contribution in the improvement of the manuscript.publishe