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Unveiling the startup characteristics of pump as turbine using computational and experimental techniques
Get PDFOver time, the interest in using pumps as turbines (PATs) instead of conventional turbines has increased. The nature and operation challenges of hydraulic resources necessitate frequent starts and stops, resulting in severe fluctuations caused by fluid flow that led to machine deterioration. Gaining more insight into how the flow develops during transients allows for safe operating conditions, effective production planning, and estimating the cost variation due to operational changes. Currently, there are limited studies on the properties of pumps that function as turbines (PATs) at startup. This work analyzes the PAT's transient behavior over time while the system is starting up. A test rig was constructed for the centrifugal PAT to reveal its transient characteristics during the start-up process. In addition to the experiments, flow-dynamic simulations were run using ANSYSFluent. The rotating part's angular velocity was validated against experimental data. Transient characteristics such as the flow rate, head, torque, and tangential force of the PAT, etc., as well as the internal flow during the start-up, were analyzed. During the start-up transient phase, the transient characteristic parameters such as pump rotational speed, head, and flow rate change significantly. As the rotating speed approaches the rated speed, there is an increase in the transient impact head to a peak that is 2.04 times that of the rated head. The numerical simulation's outcomes and the experimental data were in excellent agreement
Testing the contribution of vertebrate predators and leaf traits to mainland-island differences in insect herbivory on oaks
Get PDFEcological theory predicts that herbivory should be weaker on islands than on mainland based on the assumption that islands have lower herbivore abundance and diversity. However, empirical tests of this prediction are rare, especially for insect herbivores, and those few tests often fail to address the mechanisms behind island-mainland divergence in herbivory. In particular, past studies have not addressed the relative contribution of top-down (i.e. predator-driven) and bottom-up (i.e. plant-driven) factors to these dynamics. To address this, we experimentally excluded insectivorous vertebrate predators (e.g. birds, bats) and measured leaf traits associated with herbivory in 52 populations of 12 oak (Quercus) species in three island-mainland sites: The Channel Islands of California vs. mainland California, Balearic Islands vs. mainland Spain, and the island Bornholm vs. mainland Sweden (N = 204 trees). In each site, at the end of the growing season, we measured leaf damage by insect herbivores on control vs. predator-excluded branches and measured leaf traits, namely: phenolic compounds, specific leaf area, and nitrogen and phosphorous content. In addition, we obtained climatic and soil data for island and mainland populations using global databases. Specifically, we tested for island-mainland differences in herbivory, and whether differences in vertebrate predator effects or leaf traits between islands and mainland contributed to explaining the observed herbivory patterns. Supporting predictions, herbivory was lower on islands than on mainland, but only in the case of Mediterranean sites (California and Spain). We found no evidence for vertebrate predator effects on herbivory on either islands or mainland in any study site. In addition, while insularity affected leaf traits in some of the study sites (Sweden-Bornholm and California), these effects were seemingly unrelated to differences in herbivory. Synthesis. Our results suggest that vertebrate predation and the studied leaf traits did not contribute to island-mainland variation patterns in herbivory, calling for more nuanced and comprehensive investigations of predator and plant trait effects, including measurements of other plant traits and assessments of predation by different groups of natural enemies.La teor & iacute;a ecol & oacute;gica predice que la herbivor & iacute;a ha de ser m & aacute;s d & eacute;bil en las islas que en el continente, ya que las islas tienen una menor abundancia y diversidad de herb & iacute;voros. Sin embargo, todav & iacute;a no contamos con suficiente evidencia emp & iacute;rica que apoye estas predicciones, especialmente en lo que se refiere a la herbivor & iacute;a por insectos, y los pocos estudios que existen a menudo no abordan los mecanismos que generan estos patrones de divergencia entre islas y continente en los niveles de herbivor & iacute;a. En particular, las investigaciones previas no han examinado la contribuci & oacute;n relativa de las fuerzas top-down (es decir, efectos mediados por los depredadores) y bottom-up (es decir, efectos mediados por los rasgos funcionales de las plantas) en estas din & aacute;micas. En este trabajo, excluimos experimentalmente a depredadores insect & iacute;voros vertebrados (p. ej., aves, murci & eacute;lagos) y medimos rasgos foliares asociados con la herbivor & iacute;a en 52 poblaciones de 12 especies de robles (Quercus) en tres sitios insulares y continentales: las Islas del Canal de California vs. California continental, las Islas Baleares vs. Espa & ntilde;a continental, y la isla de Bornholm vs. Suecia continental (N = 204 & aacute;rboles). En cada sitio, al final de la & eacute;poca de crecimiento, medimos el da & ntilde;o foliar causado por insectos herb & iacute;voros en ramas control vs. ramas con exclusi & oacute;n de depredadores, y medimos diferentes rasgos foliares, en particular, la concentraci & oacute;n de compuestos fen & oacute;licos, el & aacute;rea foliar espec & iacute;fica y el contenido de nitr & oacute;geno y f & oacute;sforo. Adem & aacute;s, obtuvimos datos clim & aacute;ticos y de suelo de las poblaciones insulares y continentales utilizando bases de datos globales. Espec & iacute;ficamente, evaluamos los efectos de la insularidad sobre la herbivor & iacute;a y si exist & iacute;an patrones contrastados de los efectos de depredaci & oacute;n y expresi & oacute;n de rasgos foliares entre islas y continentes que contribuyesen a explicar los patrones observados en la herbivor & iacute;a. De acuerdo con la teor & iacute;a ecol & oacute;gica, la herbivor & iacute;a fue menor en las islas en comparaci & oacute;n con el continente, pero solo en el caso de los sitios mediterr & aacute;neos (California y Espa & ntilde;a). No encontramos evidencia de efectos de los depredadores sobre la herbivor & iacute;a en ninguno de los sitios de estudio, ya sea en las islas o en el continente. Adem & aacute;s, aunque la insularidad afect & oacute; a la expresi & oacute;n de rasgos foliares en algunos de los sitios de estudio (Suecia-Bornholm y California), estos efectos no estuvieron aparentemente relacionados con las diferencias observadas en la herbivor & iacute;a. S & iacute;ntesis. Nuestros resultados sugieren que la depredaci & oacute;n por vertebrados y los rasgos foliares estudiados no contribuyeron a los patrones de variaci & oacute;n entre islas y continente observados en los niveles de herbivor & iacute;a, lo que plantea la necesidad de investigaciones m & aacute;s exhaustivas que incluyan la evaluaci & oacute;n de otros rasgos funcionales y evaluaciones de la depredaci & oacute;n por otros grupos de enemigos naturales de los herb & iacute;voros
Effect of Plant Identity in Wheat Mixtures on English Grain Aphid (Sitobion avenae) Control
Get PDFField experiments have demonstrated that wheat mixtures differ in their ability to regulate aphid populations. To further investigate the effectiveness of wheat mixtures (Triticum aestivum and Triticum turgidum) in controlling aphids, we conducted both laboratory and greenhouse experiments. Specifically, we assessed the associational resistance of two wheat mixtures (Florence-Aurora with Forment, Florence-Aurora with Montcada), and their respective monocultures, in different stages of the aphid host selection process. We analysed aphid acceptance rate, population growth, and load under different wheat treatments. Additionally, we characterised wheat aboveground biomass and nitrogen content as important functional traits for aphid resistant. Aphid acceptance decreased in plants of cv. Forment when exposed to volatiles from undamaged Florence-Aurora plants, whereas the other tested combinations tested had no effect. Aphids performed differently in the two mixtures: Florence-Aurora mixed with Forment significantly reduced aphid population growth and load compared to the monocultures, whereas the combination of Florence-Aurora with Montcada wheat had no effect on aphid performance. The plant-plant interactions also modified the analysed traits. Nitrogen content of Florence-Aurora wheat plants was reduced when mixed with Forment wheat, which may explain the lower aphid load observed in plants of cv. Florence-Aurora when mixed with plants of cv. Forment. However, mixing wheats with similar aboveground biomass resulted in an increase in the average biomass of plants of both cultivars which could have led to a higher aphid population. The data supports the idea of right neighbour, as the benefits of wheat mixtures for aphid control were determined by the identity of the combined plants (or species). Finally, our results suggest that associating wheats with different traits may promote facilitative interactions, which in turn enhances associational resistance, whereas the combination of wheats with similar traits may result in competitive interactions that may hinder aphid control benefits
Herding cats: integrative leadership strategies in inter- and transdisciplinary research programs
Get PDFThis paper focuses on the critical role of integrative leadership in inter- and transdisciplinary (ITD) research programs. ITD programs have become one of academia's responses to address contemporary sustainability challenges. Fulfilling the promise of such programs is extraordinarily challenging for all involved participants, but especially for program leaders who have to ensure that the perspectives of the involved program participants become truly integrated and that final and useful synthesis outputs are created. We present six core leadership challenges and respective strategies to address them to advance integration within ITD programs. These challenges include (1) mastering complexity and ambiguity, (2) advancing decision-making with lateral leadership, (3) ensuring responsibility and accountability, (4) setting program boundaries, (5) selecting suitable projects, and (6) dealing with misconceptions. We derived these challenges and respective strategies from both leading and studying in-depth three ITD programs focusing on sustainability issues in Switzerland. With this paper, we intend to promote awareness about the range of leadership challenges in ITD programs and provide actionable knowledge, which can support in particular fellow and future leaders, but also funders and heads of research institutions in their efforts to realize the integrative potential of such programs.Graphical abstractImage 1: (c) Eawag: Lisa Deutsch & Sabine Hoffmann; St & uuml;ckelberger Cartoons: Christof St & uuml;ckelberger, CC BY-NC-ND 4.
Knowledge, attitude, and practice (KAP) analysis of agricultural biologicals among smallholder farmers across three counties in Kenya
Get PDFAgricultural biologicals (agrobiologicals) can be sustainable options to manage plant pests and diseases and enhance growth. This can reduce reliance on synthetic inputs, which often come from non-renewable sources and pose risks to the environment and farmers. However, the use of agrobiologicals in Sub-Saharan Africa (SSA) is low. To understand factors leading to low adoption of Agrobiologicals in Kenya, we performed a Knowledge, Attitude and Practice (KAP) analysis among smallholder farmers in three counties in Kenya regarding agrobiologicals. 275 farmers were interviewed in Kajiado, Kiambu and Machakos counties. The farmers' knowledge on agrobiologicals was low and varied across the counties; 18-47 % of respondents were deemed knowledgeable. The main source of knowledge was neighbours (32-57 % depending on the county). Regarding the information flow, agro-dealers were the main source of information for agricultural inputs in general. More than 70 % of the farmers were not trained in employing agrobiologicals, and 70 % of the farmers stated that agrobiologicals are not effective. Still, between 46 % (Kajiado) and 18 % (Machakos) used agrobiologicals in their farming practices. The number of years in farming positively correlated with knowledge of agrobiologicals, but not attitude and practice. Possibly, the low knowledge regarding agrobiologicals influenced attitude and practice; however perceived sufficient knowledge of agrobiologicals did not translate into an increased use, indicating that knowledge alone is not sufficient to ensure use among smallholder farmers. These findings call for new strategies to promote agrobiologicals to smallholder farmers in SSA
Ecological and evolutionary consequences of ecosystem warming in fish
Get PDFClimate warming forces ectothermic organisms to shift their spatial or temporal distribution, acclimatize or adapt to new thermal conditions to survive. Fish, as key ectotherms with significant ecological roles and socio-economic values, have been widely studied in this context. However, whether warming induces evolution in wild fish populations over time, and if so, how such evolutionary effects can impact the community and ecosystem more broadly remain largely unknown.In this thesis, I investigated the effects of ecosystem-warming on fish by comparing traits and genomes of Eurasian perch from an artificially heated area with those from a neighbouring unheated area over four decades. Long-term trait data analyses showed that perch mature earlier and at smaller body sizes with increased reproductive investment in the first generations exposed to warming. After four to eight generations of warming, size at maturation varied more, indicating an evolutionary component in maturation-related trait responses to warming. Utilising a customised DNA extraction protocol, I obtained high-quality whole genome sequencing data for perch from historical archival bones as well as contemporary muscle samples. Selection signatures in single nucleotide variants were revealed between perch from the heated and unheated area over time, suggesting natural selection due to warming. Lastly, I conducted a mesocosm experiment, exposing a pelagic food web module to a temperature gradient using perch larvae from both the heated and unheated areas. Fish from the heated area may have adapted to warming in feeding-related traits, as indicated by differences in their zooplankton prey community composition compared to fish from the unheated area.Overall, the thesis demonstrates that warming can impose evolutionary and ecological consequences on fish in the wild, and underscores how such consequences can propagate through species interactions and influence other components in the ecosystem. This thesis emphasises the importance of synthesising research on ecology and evolution to better understand how ectotherms respond to rising temperatures and the biological processes involved, especially in the face of intensifying climate warming challenges
Evolved and Plastic Gene Expression in Adaptation of a Specialist Fly to a Novel Niche
Get PDFHow gene expression evolves to enable divergent ecological adaptation and how changes in gene expression relate to genomic architecture are pressing questions for understanding the mechanisms enabling adaptation and ecological speciation. Furthermore, how plasticity in gene expression can both contribute to and be affected by the process of ecological adaptation is crucial to understanding gene expression evolution, colonisation of novel niches and response to rapid environmental change. Here, we investigate the role of constitutive and plastic gene expression differences between host races, or host-specific ecotypes, of the peacock fly Tephritis conura, a thistle bud specialist. By cross-fostering larvae to new buds of their natal host plant or the alternative, novel host plant, we uncover extensive constitutive differences in gene expression between the host races, especially genes associated with processing of host plant chemicals. However, evidence for expression plasticity was minimal and limited to the ancestral host race. Genes with host race-specific expression are found more often than expected within a large inversion in the T. conura genome, adding to evidence that inversions are important for enabling diversification in the face of gene flow and underscores that altered gene expression may be key to understanding the evolutionary consequences of inversions
Arbuscular mycorrhiza fungi (AMF) mediated biofortification of micronutrients, protein characteristics, and γ-aminobutyric acid in sorghum grown on vertisols in the central clay plains of Sudan
Get PDFHidden hunger and micronutrient deficiencies are critical global challenges, particularly in developing nations. Arbuscular mycorrhizal fungi (AMF) enhance plant nutrient uptake and may provide a sustainable solution. This study evaluated the impact of locally sourced AMF inocula on the nutritional quality of four sorghum cultivars grown on vertisols in Sudan's central clay plains. A split-plot field trial at two locations assessed AMF inoculation (main plot factor) and sorghum cultivars (sub-plot factor) across three replicates. AMF inoculation significantly improved grain crude protein (10.5% to 11.9%), in-vitro protein digestibility (60.8 to 69.9 g/100 g), protein solubility (4.0 to 4.9 g/100 g), and gamma-aminobutyric acid (GABA) content (0.6 to 2.1 mg/g). Total and bioavailable iron and zinc levels in AMF-treated grains (40.6% and 40.3%, respectively) exceeded those in non-treated grains (36.3% and 35.8%, respectively). Phytate content, an anti-nutrient, decreased significantly (339.9 to 238.2 mg/100 g) with AMF, showing an inverse relationship with micronutrient levels. Partial least squares regression analysis identified cultivar P954063 with AMF inoculation at Medani as optimal for enhancing grain nutritional quality. These findings highlight the potential of locally produced AMF inoculum to alleviate micronutrient deficiencies in Sudan and similar regions
Parasite spillover rather than niche expansion explains infection of host brain by diplostomid eye flukes
Get PDFParasites often occupy specific sites within their host, which has important implications for host performance and parasite transmission. Nonetheless, parasitic infections can occur beyond their typical location within a host, significantly altering host-parasite interactions. Yet, the causes behind the atypical tissue tropism are poorly understood. Here, we focus on a ubiquitous group of diplostomid parasites that form diverse communities in fish eyes. We used targeted DNA metabarcoding (cytochrome c oxydase subunit 1, COX1, 250 bp) to evaluate potential mechanisms underlying eye parasite atypical tissue tropism to the brain of two widespread fish species (Eurasian perch and common roach). We found that the most common eye-infecting species (Tylodelphys clavata, Diplostomum baeri) are present in the brains of perch but not in roach. The bipartite network comprising 5 species and 24 mitochondrial haplotypes revealed no brain-specific haplotypes, indicating an apparent lack of genetic divergence between brain- and eye-infecting parasites. Instead, the prevalence, intensity and diversity of eye infections were positively correlated with brain infections. Thus, our results suggest that the most parsimonious mechanism underlying brain infection is density-dependent spillover rather than parasite divergence-driven niche expansion. We anticipate that 'off-target' infections are likely to be severely underestimated in nature with important ecological, evolutionary and medical implications
In a Changing World-An Economical Comparison Between Traditional and Wet-And-Drought-Resistant Grasses in Swedish Cattle Production Under Different Weather Scenarios
Get PDFThis study compared the profitability when feeding silages of different grass species in enterprises with either dairy cows, beef breed bulls, or beef suckler cows. Traditional (TR) grasses timothy and meadow fescue was compared to the alternative wet-and-drought-resistant (WD) grasses tall fescue, festulolium, and reed canary grass in three different weather scenarios with either normal conditions (Ref), delayed late harvest time due to wet weather conditions (Wet), or decreased grass yield due to dry weather conditions (Dry). Contribution margin calculation was conducted for three geographical regions in Sweden. In the Ref and Wet scenarios, TR was more competitive than WD for dairy cows and beef bulls in all regions. Also in the Dry scenario, TR was more competitive than WD for dairy cows, as the lower production cost of the WD was outweighed by a lower milk yield of cows fed WD compared to cows fed TR. Contrary, for beef bulls, WD gave a higher contribution margin than TR did in the Dry scenario, where the break-even for WD being superior over TR occurred when more than every second year was dry. WD reed canary grass was always more competitive than TR and WD festulolium for beef cows