306 research outputs found

    Potential advantages in heat and power production when biogas is collected from several digesters using dedicated pipelines - A case study in the "Province of West-Flanders" (Belgium)

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    In the case study “West-Flanders” costs of electricity and heat production are estimated if a dedicated biogas grid using pipelines would be implemented to centralize energy production in a region. Heat may not be used effectively at digester sites, e.g. because of a change in treatment of digestate. A large scale centralized combined heat and power (CHP) engine can produce additional electrical power at a hub, i.e. central collection point, and has lower specific costs compared to decentralized CHPs at digester sites. A biogas transport model is used to calculate transport costs in a grid. These costs, partly balanced by a scale advantage in CHP costs, are attributed to the additional electrical energy (80%) and heat (20%) produced. If the hub is at a digester site, costs of additional electricity can be as low as 4.0 €ct kWhe−1 and are in many cases below 12 €ct kWhe−1, i.e. in the same order of magnitude or lower than costs of electricity from biogas produced using separate CHPs at the different digester sites; costs of heat at the hub show to be lower than 1 €ct kWhth−1 assuming an effective heat use of 50%. In case a hub is situated at a location with high potential heat demand, i.e. a heat sink, transport of biogas from one digester only to a central located hub can provide 3.4 MWth of heat at 1.95 €ct kWhth−1. For such a centrally located hub additional electrical energy costs show to be slightly higher, but with three or more digesters these costs are lower than 20 €ct kWhe−1 and heat costs are around 0.5 €ct kWhth−1. With a centralized hub more renewable energy is produced, i.e. a more efficient use of biomass feedstock. It is concluded that costs for additional electricity and heat can be at a competing level and scale advantages in a CHP can be a driver to collect biogas at a hub using a biogas grid

    Errors in transrectal ultrasonic planimetry of the prostate: Computer simulation of volumetric errors applied to a screening population

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    Three systemic errors in routine ultrasonic planimetric volume measurements of the prostate were assessed. A computer model using ellipsoids was used to simulate the step section technique and different forms of rotational movements of the prostate during planimetry. The planimetric volume was up to 12% smaller than the exact volume, depending on the degree of rotational movement, the shape, and the length of the ellipsoid. In vivo study of a screening popul

    Impact assessment of different battery energy storage technologies in distribution grids with high penetration of renewable energies

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    The need for increasing further the penetration of Renewable Energy Sources (RESs) is demanding a change in the way distribution grids are managed. In particular, the RESs intermittent and stochastic nature is finding in Battery Energy Storage (BES) systems its most immediate countermeasure. This work presents a reality-based assessment and comparison of the impact of three different BES technologies on distribution grids with high RES penetration, namely Li-ion, Zn-Air and Redox Flow. To this end, a benchmark distribution grid with real prosumers’ generation and load profiles is considered, with the RES penetration purposely scaled up in such a way as to violate the grid operational limits. Then, further to the BES(s) placement on the most affected grid location(s), the impact of the three BES types is assessed considering two Use Cases: 1) Voltage & Congestion Management and 2) Peak Shaving & Energy shifting. Assessment is conducted by evaluating a set of technical Key Performance Indicators (KPIs), together with a simplified economic analysis. © 2022, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved

    Experimental evidence for inherent Lévy search behaviour in foraging animals

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    Recently, Lévy walks have been put forward as a new paradigm for animal search and many cases have been made for its presence in nature. However, it remains debated whether Lévy walks are an inherent behavioural strategy or emerge from the animal reacting to its habitat. Here, we demonstrate signatures of Lévy behaviour in the search movement of mud snails (Hydrobia ulvae) based on a novel, direct assessment of movement properties in an experimental set-up using different food distributions. Our experimental data uncovered clusters of small movement steps alternating with long moves independent of food encounter and landscape complexity. Moreover, size distributions of these clusters followed truncated power laws. These two findings are characteristic signatures of mechanisms underlying inherent Lévy-like movement. Thus, our study provides clear experimental evidence that such multi-scale movement is an inherent behaviour rather than resulting from the animal interacting with its environmen

    Accounting for aboveground carbon storage in shrubland and woodland ecosystems in the Great Basin

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    Improving the accuracy of carbon accounting in terrestrial ecosystems is critical for understanding carbon fluxes associated with land cover change, with significant implications for global carbon cycling and climate change. Semi‐arid ecosystems account for an estimated 45% of global terrestrial ecosystem area and are in many locations experiencing high degrees of degradation. However, aboveground carbon accounting has largely focused on tropical and forested ecosystems, while drylands have been relatively neglected. Here, we used a combination of field estimates, remotely sensed data, and existing land cover maps to create a spatially explicit estimate of aboveground carbon storage within the Great Basin, a semi‐arid region of the western United States encompassing 643,500 km2 of shrubland and woodland vegetation. We classified the region into seven distinct land cover categories: pinyon‐juniper woodland, sagebrush steppe, salt desert shrub, low sagebrush, forest, non‐forest, and other/excluded, each with an associated carbon estimate. Aboveground carbon estimates for pinyon‐juniper woodland were continuous values based on tree canopy cover. Carbon estimates for other land cover categories were based on a mean value for the land cover type. The Great Basin ecosystems contain an estimated 295.4 Tg in aboveground carbon, which is almost double the previous estimates that only accounted for forested ecosystems in the same area. Aboveground carbon was disproportionately stored in pinyon‐juniper woodland (43.7% carbon, 16.9% land area), while the shrubland systems accounted for roughly half of the total land area (49.1%) and one‐third of the total carbon. Our results emphasize the importance of distinguishing and accounting for the distinctive contributions of shrubland and woodland ecosystems when creating carbon storage estimates for dryland regions

    Alinhamento interpessoal, representacional e morfossintático na Gramática Discursivo-Funcional

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    Este artigo se debruça sobre o mapeamento entre os Níveis Interpessoal, Representacional e Morfossintático da gramática, o chamado alinhamento, segundo o arcabouço da Gramática Discursivo-Funcional (GDF). Propõe uma tipologia das línguas baseada no que a sua organização morfossintática codifica: distinções pragmáticas (p.ex. em Tagalo), distinções semânticas (p.ex. em Achém), ou distinções inerentes à morfossintaxe (p.ex. em Inglês, Basco ou a língua Kham). A inclusão tanto do Sujeito como do Objeto e de línguas tanto acusativas como ergativas no tratamento do alinhamento morfossintático permitiu-nos abranger tipos tipologicamente mais variáveis e demonstrar o potencial da GDF para a análise contrastiva das línguas.<br>Within the framework of Functional Discourse Grammar (FDG), alignment concerns the relations between the Interpersonal, Representational and Morphosyntactic Levels of grammar. This article proposes a typology of languages based upon what we find to be encoded in their morphosyntactic organization: pragmatic distinctions (as in Tagalog), semantic distinctions (as in Acheh), or distinctions inherent to the morphosyntax (as in English, Basque and Kham). By including both subject and object, and both accusative and ergative languages in our treatment of morphosyntactic alignment, we provide a better coverage of typological variation and show the potential of FDG for cross-linguistic analysis

    Invasion speeds for structured populations in fluctuating environments

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    We live in a time where climate models predict future increases in environmental variability and biological invasions are becoming increasingly frequent. A key to developing effective responses to biological invasions in increasingly variable environments will be estimates of their rates of spatial spread and the associated uncertainty of these estimates. Using stochastic, stage-structured, integro-difference equation models, we show analytically that invasion speeds are asymptotically normally distributed with a variance that decreases in time. We apply our methods to a simple juvenile-adult model with stochastic variation in reproduction and an illustrative example with published data for the perennial herb, \emph{Calathea ovandensis}. These examples buttressed by additional analysis reveal that increased variability in vital rates simultaneously slow down invasions yet generate greater uncertainty about rates of spatial spread. Moreover, while temporal autocorrelations in vital rates inflate variability in invasion speeds, the effect of these autocorrelations on the average invasion speed can be positive or negative depending on life history traits and how well vital rates ``remember'' the past

    The inner centromere is a biomolecular condensate scaffolded by the chromosomal passenger complex.

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    The inner centromere is a region on every mitotic chromosome that enables specific biochemical reactions that underlie properties, such as the maintenance of cohesion, the regulation of kinetochores and the assembly of specialized chromatin, that can resist microtubule pulling forces. The chromosomal passenger complex (CPC) is abundantly localized to the inner centromeres and it is unclear whether it is involved in non-kinase activities that contribute to the generation of these unique chromatin properties. We find that the borealin subunit of the CPC drives phase separation of the CPC in vitro at concentrations that are below those found on the inner centromere. We also provide strong evidence that the CPC exists in a phase-separated state at the inner centromere. CPC phase separation is required for its inner-centromere localization and function during mitosis. We suggest that the CPC combines phase separation, kinase and histone code-reading activities to enable the formation of a chromatin body with unique biochemical activities at the inner centromere
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