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- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 5. |
- Aronsson, Pär, et al.
(författare)
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Impact of nitrogen fertilization to short-rotation willow coppice plantations grown in Sweden on yield and economy
- 2014
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Ingår i: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 7, s. 993-1001
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Tidskriftsartikel (refereegranskat)abstract
- A fertilization trial was carried out in established short-rotation willow coppice (SRWC) plantations of two bred varieties of willow (Salix spp.; "Tora" and "Jorr") at five sites in central Sweden between 2008 and 2010. Mineral nitrogen was applied at four different rates: No fertilization (Control), 160 kg nitrogen ha(-1) as a single dose after harvest (Economy), 60-100-60 kg nitrogen ha(-1) in year 1-2-3 (Normal), and 160 kg nitrogen ha(-1) year(-1) in years 1-3 (Intensive), using a randomized block design with four replicates. The yield response (biomass increase per kg fertilizer nitrogen) was 65, 67 and 46 kg kg(-1) in the Economy, Normal and Intensive treatments, respectively. The results from the fertilization trial were used for economic calculations of different fertilization strategies given varying costs for fertilization and marginal value of the increased yield (price received for wood chips minus the costs for harvest and transportation of wood chips to a district heating plant). Comparative calculations were made based on data from a previous fertilization trial during the first cutting cycle of old, non-bred varieties. The calculations showed positive net present values of fertilizing bred willow varieties given a realistic fertilization response and a price for wood chips close to the market price for forestry-based wood chips in Sweden.
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| 6. |
- Aronsson, Pär, et al.
(författare)
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Treatment of landfill leachate by irrigation of willow coppice - Plant response and treatment efficiency
- 2010
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 158:3, s. 795-804
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Tidskriftsartikel (refereegranskat)abstract
- Landfill leachates usually need to be treated before discharged. and using soil-plant systems for this has gained substantial interest in Sweden and in the UK A three-year field study was conducted in central Sweden to quantify plant response, treatment efficiency and impact on groundwater quality of landfill leachate irrigation of short-rotation willow coppice (Salix) Two willow varieties were tested and four irrigation regimes in sixteen 400-m(2) plots. The willow plants did not react negatively, despite very high annual loads of nitrogen (<= 2160 kg N/ha), chloride (<= 8600 kg Cl/ha) and other elements. Mean annual growth was 15. 98 and 12.6 tonnes DM/ha during years 1-3 For one of two willow varieties tested. relative leaf length accurately predicted growth rate. Irrigation resulted in elevated groundwater concentrations of all elements applied. Treatment efficiency varied considerably for different elements, but was adequate when moderate loads were applied. (C) 2009 Elsevier Ltd All rights reserved.
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| 7. |
- Dale, Virginia H., et al.
(författare)
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Status and prospects for renewable energy using wood pellets from the southeastern United States
- 2017
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Ingår i: Global Change Biology Bioenergy. - : Wiley-Blackwell. - 1757-1693 .- 1757-1707. ; 9:8, s. 1296-1305
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Tidskriftsartikel (refereegranskat)abstract
- The ongoing debate about costs and benefits of wood-pellet based bioenergy production in the southeastern United States (SE USA) requires an understanding of the science and context influencing market decisions associated with its sustainability. Production of pellets has garnered much attention as US exports have grown from negligible amounts in the early 2000s to 4.6 million metric tonnes in 2015. Currently, 98% of these pellet exports are shipped to Europe to displace coal in power plants. We ask, 'How is the production of wood pellets in the SE USA affecting forest systems and the ecosystem services they provide?' To address this question, we review current forest conditions and the status of the wood products industry, how pellet production affects ecosystem services and biodiversity, and what methods are in place to monitor changes and protect vulnerable systems. Scientific studies provide evidence that wood pellets in the SE USA are a fraction of total forestry operations and can be produced while maintaining or improving forest ecosystem services. Ecosystem services are protected by the requirement to utilize loggers trained to apply scientifically based best management practices in planning and implementing harvest for the export market. Bioenergy markets supplement incomes to private rural landholders and provide an incentive for forest management practices that simultaneously benefit water quality and wildlife and reduce risk of fire and insect outbreaks. Bioenergy also increases the value of forest land to landowners, thereby decreasing likelihood of conversion to nonforest uses. Monitoring and evaluation are essential to verify that regulations and good practices are achieving goals and to enable timely responses if problems arise. Conducting rigorous research to understand how conditions change in response to management choices requires baseline data, monitoring, and appropriate reference scenarios. Long-term monitoring data on forest conditions should be publicly accessible and utilized to inform adaptive management.
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| 8. |
- Dimitriou, Ioannis, et al.
(författare)
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A Queue-based Random Access Scheme in Network-level Cooperative Wireless Networks
- 2019
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Ingår i: ICC 2019 - 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC). - : IEEE. - 9781538680889
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Konferensbidrag (refereegranskat)abstract
- In this work, we consider a relay assisted adaptive queue-aware cooperative random access wireless network with multipacket (MPR) reception capabilities. The network consists of N sources transmitting packets to a common destination node with the aid of two relay nodes equipped with queues. The relays assist the sources by forwarding the packets that failed to reach the destination, by using a queue-based transmission control mechanism. Moreover, the relays have also their own traffic. We investigate the stability conditions and the throughput performance of the network for the full MPR channel model. Moreover, we derive expressions for the average queueing delay with the aid of the theory of boundary value problems for the asymmetric two-user network. We evaluate numerically the presented theoretical analysis.
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| 9. |
- Dimitriou, Ioannis, et al.
(författare)
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A RANDOM ACCESS G-NETWORK: STABILITY, STABLE THROUGHPUT, AND QUEUEING ANALYSIS
- 2021
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Ingår i: Probability in the engineering and informational sciences (Print). - : CAMBRIDGE UNIV PRESS. - 0269-9648 .- 1469-8951. ; 35:1, s. 111-137
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Tidskriftsartikel (refereegranskat)abstract
- The effect of signals on stability, stable throughput region, and delay in a two-user slotted ALOHA-based random-access system with collisions is considered. This work gives rise to the development of random access G-networks, which can model security attacks, expiration of deadlines, or other malfunctions, and introduce load balancing among highly interacting queues. The users are equipped with infinite capacity buffers accepting external bursty arrivals. We consider both negative and triggering signals. Negative signals delete a packet from a user queue, while triggering signals cause the instantaneous transfer of packets among user queues. We obtain the exact stability region, and show that the stable throughput region is a subset of it. Moreover, we perform a compact mathematical analysis to obtain exact expressions for the queueing delay by solving a non-homogeneous Riemann boundary value problem. A computationally efficient way to obtain explicit bounds for the expected number of buffered packets at user queues is also presented. The theoretical findings are numerically evaluated and insights regarding the system performance are derived.
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| 10. |
- Dimitriou, Ioannis
(författare)
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A review of the impacts of Short Rotation Coppice cultivation on water issues
- 2009
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Ingår i: Landbauforschung. - 0458-6859. ; 59, s. 197-206
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Forskningsöversikt (refereegranskat)abstract
- Cultivation of Short Rotation Coppice (SRC) with poplars (Populus sp.) and willows (Salix sp.) for production of biomass for heat and/or electricity is energy effective and coincides with several environmental objectives. Since an increase of cultivation of poplar and willow SRC has been projected in Europe, the consequent implications on water issues arises. For instance, water use of SRC can be higher compared to annual agricultural crcps or previous set-aside land, but water quality can be improved The paper examines such implications based on a review of the existing scientific literature. Rates of evapotranspiration (V(ET)) of SRC are reported to be fairly higher than arable crops, but reported values vary markedly and are related to site-specific factors such as the local precipitation and conditions (e.g soil type, temperature, groundwater level), the species/sorts and the age of the crop, and their interactions. Despite the predicted local effects on water balances, effects on water balances/hydrology on catchment levels have not been reported or justified This, combined with the reported positive effects of SRC on groundwater quality in terms of nutrient leaching, imoly average positive effects of SRC on water issues, if the identified potentially negative impacts would be considered and minimized. For this, comparisons of V ET between SRC and arable crops, and the relation of V ET with local precipitation and other local factors (root development, groundwater availability) should be better examined and combined with positive effects of SRC on groundwater leaching compared to other crops Upscaling of water issues for SRC is needed to promote future decision-making processes with respect to the envisaged broadening of SRC on productive but also on marginal soils.
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