| 1. |
- Gardella, Eusebio, et al.
(författare)
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Zero-product balanced algebras
- 2023
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Ingår i: Linear Algebra and Its Applications. - 0024-3795. ; 670, s. 121-153
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Tidskriftsartikel (refereegranskat)abstract
- We say that an algebra is zero-product balanced if ab 0 c and a 0 bc agree modulo tensors of elements with zero-product. This is closely related to but more general than the notion of a zero-product determined algebra introduced and developed by Bresar, Villena and others. Every surjective, zero-product preserving map from a zero-product balanced algebra is automatically a weighted epimorphism, and this implies that zero-product balanced algebras are determined by their linear and zero-product structure. Further, the commutator subspace of a zero-product balanced algebra can be described in terms of square-zero elements. We show that a commutative, reduced algebra is zero-product balanced if and only if it is generated by idempotents. It follows that every commutative, zero-product balanced algebra is spanned by nilpotent and idempotent elements. (c) 2023 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons .org /licenses /by /4 .0/).
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| 2. |
- Pilotto, Francesca, et al.
(författare)
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Late Holocene anthropogenic landscape change in northwestern Europe impacted insect biodiversity as much as climate change did after the last Ice Age
- 2022
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : Royal Society Publishing. - 0962-8452 .- 1471-2954. ; 289:1977
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Tidskriftsartikel (refereegranskat)abstract
- Since the last Ice Age (ca 115 000–11 700 years ago), the geographical ranges of most plants and animals have shifted, expanded or contracted. Understanding the timing, geographical patterns and drivers of past changes in insect communities is essential for evaluating the biodiversity implications of future climate changes, yet our knowledge of long-term patterns is limited. We applied a network modelling approach to the recent fossil record of northwestern European beetles to investigate how their taxonomic and trait composition changed during the past 16 000 years. We found two major changes in beetle faunas 4000–3500 and 10 000–9500 years ago, coinciding with periods of human population growth in the Late Holocene and climate warming in the Early Holocene. Our results demonstrate that humans have affected insect biodiversity since at least the introduction of agropastoralism, with landscape-scale effects that can be observed at sites away from areas of direct human impact.
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| 3. |
- Nilsson, Mikael, et al.
(författare)
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Learning Based Image Segmentation of Pigs in a Pen
- 2014
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Ingår i: ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- As farms are getting bigger with more animals, less manual supervision and attention can be given the animals on both group and individual level. In order not to jeopardize animal welfare, automated supervision is in some way already in use. Function and control of ventilation is already in use in modern pig stables, e.g. by the use of sensors for temperature, relative humidity and malfunction connected to alarm. However, by measuring continuously directly on the pigs, more information and more possibilities to adjust production inputs would be possible. In this work, the focus is on a key image processing algorithm aiding such a continuous system - segmentation of pigs in images from video. The proposed solution utilizes extended state-of-the-art features in combination with a structured prediction framework based on a logistic regression solver using elastic net regularization. Objective results on manually segmented images indicate that the proposed solution, based on learning, performs better than approaches suggested in recent publications addressing pig segmentation in video.
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| 4. |
- Rönnegård, Lars, et al.
(författare)
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Modelling dominance in a flexible intercross analysis
- 2009
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Ingår i: BMC Genetics. - : Springer Science and Business Media LLC. - 1471-2156. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Conclusion: We have extended FIA to include QTL dominance effects. The power of FIA was superior, or similar, to standard regression methods for QTL effects with dominance. The difference in power for FIA with or without dominance is expected to be small as long as the QTL effects are not overdominant. We suggest that FIA with only additive effects should be the standard model to be used, especially since it is more computationally efficient.
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| 5. |
- Svensson, Catarina, et al.
(författare)
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Dairy farmer and farm staff attitudes and perceptions regarding daily milk allowance to calves
- 2023
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Ingår i: Journal of Dairy Science. - : Elsevier. - 0022-0302 .- 1525-3198. ; 106:10, s. 7220-7239
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Tidskriftsartikel (refereegranskat)abstract
- The benefits of feeding calves more milk are increasingly being recognized by dairy farmers. However, most producers have still not implemented higher feeding plans. The aim of the present study was to gain a deeper understanding of farmer and farm staff attitudes, and the perceptions and factors considered in their decision-making regarding daily milk allowances. We collected data through focus group interviews with dairy farmers, farm managers, and calf-care workers who were selected using purposive and snowball sampling. In total, 40 persons (24 women and 16 men) joined a focus group interview (6 in all, each with 5–8 participants). Interviews were recorded, and recordings were transcribed and analyzed thematically. Participants had contrasting opinions about the minimum, maximum, and recommended daily milk allowances to their calves. Their suggested lowest daily milk allowance to sustain animal welfare ranged from 4 to 8–10 L and the maximum allowance from 6 to 15 L. We found that farmers' and farm staff's choices and recommendations of milk-feeding protocols were influenced by a large number of factors that could be grouped into 4 themes: (1) Life beyond work, (2) Farm facilities and equipment, (3) Care of the calves, and (4) Profitability and production. Participants' considerations were similar and aimed to maximize daily milk allowance based on farm conditions. However, the allowances they described as optimal for their calves often differed from what they considered practically feasible. We found that the care of the calves and the well-being of the owners and the staff was central in the participants' decision-making, but that this care perspective was challenged by the social and economic sustainability of the farm. Most participants fed their calves twice daily and did not think that increasing that number would be practically feasible. Our results indicate that the participants' viewpoints regarding calves were important for their decision-making about milk allowances. We suggest that a more holistic perspective should be used when advising farmers about milk allowances, putting particular emphasis on the caring and social sustainability aspects of the individual farm.
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| 6. |
- Cronie, Ottmar, 1979, et al.
(författare)
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Spatiotemporal Modeling of Swedish Scots Pine Stands
- 2013
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Ingår i: Forest Science. - : Oxford University Press (OUP). - 0015-749X .- 1938-3738. ; 59:5, s. 505-516
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Tidskriftsartikel (refereegranskat)abstract
- The growth-interaction (GI) process is used for the spatiotemporal modeling of measurements of locations and radii at breast height made at three different time points of the individual trees in 10 Scots pine (Pinus sylvestris) plots from the Swedish National Forest Inventory. The GI process places trees at random locations in the study region and assigns sizes to the trees, which interact and grow with time. It has been used to model plots in previous studies and to improve the fit we suggest some modifications: a different location assignment strategy and a different open-growth (growth under negligible competition) function. We believe that the calibration data contain trees that are too small to reflect the open growth properly, which primarily affects the carrying capacity parameter. To better represent the open growth of Scots pines, we evaluate the open growth from a separate set of data (size and age measurements of older and larger single Scots pines). A linear relationship is found between the plot's estimated site indices and the sizes, and this is exploited in the estimation of the carrying capacity. We finally estimate the remaining GI process parameters and test the goodness of fit on simulated predictions from the fitted model.
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| 7. |
- Piikki, Kristin, et al.
(författare)
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Digital soil mapping of arable land in Sweden – Validation of performance at multiple scales
- 2019
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 352, s. 342-350
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we produced a detailed digital soil map of topsoil texture and soil organic matter (SOM) content for 2.4 million ha of arable land in Sweden (DSMS). Three spatially exhaustive datasets (a laser-scanned digital elevation model, airborne gamma radiation scanning data and a legacy Quaternary deposit map) were calibrated against topsoil texture and SOM content in around 13,500 soil samples, using multivariate adaptive regression splines (MARSplines) modelling. We then deployed the MARSplines models to produce raster maps (50 m x 50 m) of clay, sand and SOM content. The modelling procedure was validated by an independent dataset of about 24,000 samples clustered on 544 farms (with a local sample density of one per 3 ha). The error in clay content was < 8% in 75% of the validation samples, while for sand content and SOM content it was 13% and 2%, respectively. Corresponding values for the farm-average level were 6%, 11% and 2%, respectively. Modelling efficiency values revealed that the clay content map was a considerable improvement over the mean of the reference values at national level, regional level and, in many cases, also farm level. However, SOM content predictions showed little or no improvement over the mean of the reference samples (at any scale), due to poor correlation with the exhaustive predictor variables at all three scales investigated. The DSMS soil geodatabase will continue to be improved and have more layers added, e.g. derived layers calculated from the primary clay, sand and SOM layers by use of pedotransfer functions. Practical use of DSMS is exemplified here in an internet application for deriving prescription files for precision agriculture.
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| 8. |
- Rönnegård, Lars, et al.
(författare)
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Genetic heterogeneity of residual variance - estimation of variance components using double hierarchical generalized linear models
- 2010
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Ingår i: Genetics Selection Evolution. - : Springer Science and Business Media LLC. - 0999-193X .- 1297-9686. ; 42
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Tidskriftsartikel (refereegranskat)abstract
- Background: The sensitivity to microenvironmental changes varies among animals and may be under genetic control. It is essential to take this element into account when aiming at breeding robust farm animals. Here, linear mixed models with genetic effects in the residual variance part of the model can be used. Such models have previously been fitted using EM and MCMC algorithms.Results: We propose the use of double hierarchical generalized linear models (DHGLM), where the squared residuals are assumed to be gamma distributed and the residual variance is fitted using a generalized linear model. The algorithm iterates between two sets of mixed model equations, one on the level of observations and one on the level of variances. The method was validated using simulations and also by re-analyzing a data set on pig litter size that was previously analyzed using a Bayesian approach. The pig litter size data contained 10,060 records from 4,149 sows. The DHGLM was implemented using the ASReml software and the algorithm converged within three minutes on a Linux server. The estimates were similar to those previously obtained using Bayesian methodology, especially the variance components in the residual variance part of the model.Conclusions: We have shown that variance components in the residual variance part of a linear mixed model can be estimated using a DHGLM approach. The method enables analyses of animal models with large numbers of observations. An important future development of the DHGLM methodology is to include the genetic correlation between the random effects in the mean and residual variance parts of the model as a parameter of the DHGLM.
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| 9. |
- Crooks, Lucy, et al.
(författare)
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An Improved Method for Estimating Chromosomal Line Origin in QTL Analysis of Crosses Between Outbred Lines
- 2011
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Ingår i: G3. - : Oxford University Press (OUP). - 2160-1836. ; 1, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- Estimating the line origin of chromosomal sections from marker genotypes is a vital step in quantitative trait loci analyses of outbred line crosses. The original, and most commonly used, algorithm can only handle moderate numbers of partially informative markers. The advent of high-density genotyping with SNP chips motivates a new method because the generic sets of markers on SNP chips typically result in long stretches of partially informative markers. We validated a new method for inferring line origin, triM (tracing inheritance with Markov models), with simulated data. A realistic pattern of marker information was achieved by replicating the linkage disequilibrium from an existing chicken intercross. There were approximately 1500 SNP markers and 800 F-2 individuals. The performance of triM was compared to GridQTL, which uses a variant of the original algorithm but modified for larger datasets. triM estimated the line origin with an average error of 2%, was 10% more accurate than GridQTL, considerably faster, and better at inferring positions of recombination. GridQTL could not analyze all simulated replicates and did not estimate line origin for around a third of individuals at many positions. The study shows that triM has computational benefits and improved estimation over available algorithms and is valuable for analyzing the large datasets that will be standard in future.
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| 10. |
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