| 1. |
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| 2. |
- Ahmed, Nur, et al.
(author)
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Impact of climate change on rice insect pests and their natural enemies
- 2013
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Conference paper (peer-reviewed)abstract
- Rice is one of the important staple foods for half of the world population particularly Asian countries for their livelihood, socio-economic and nutrition. Global warming is predicted to increase frequency of precipitation/rainfall, intensity of drought and solar-radiation/UV-B radiation which might affect the intensity and severity of rice pests in one hand, but also change in other friendly arthropods on the other hand. The present studies discuss the influence of climatic factors (temperature and rainfall) on yellow stem borer (YSB), brown planthopper (BPH), green leafhopper (GLH) and their natural enemies (spider, lady bird beetle, green mirid bug). Light trap and sweep net catches of arthropods from different rice habitats were used in this study. For GLH there is a strong periodicity at 6 months and a somewhat weaker periodicity at 12 months followed by an even weaker periodicity at 3 months, especially valid for both methods of data collection (light trap and sweep-net data). Finally, for GMB there is a strong periodicity at 6 months and a somewhat weaker periodicity at 3 months followed by an even weaker periodicity at 4 months. There is a general increasing trend over the ten years seems to be present in the GLH. This corresponds to that the abundance in 2005 is generally 15 times larger than in January 1996. For LBB, there is an increasing trend of log abundance of LBB over time and shows a strong periodicity at 3 months and a somewhat weaker periodicity at 4 months followed by an even weaker periodicity at about 6 months. For Spider there is a strong periodicity at 2.4 months and a somewhat weaker periodicity at 4 months followed by an even weaker periodicities at about 3 months and 6 months. Results show an increase of maximum temperature of approximately 0.5 to 1°C over 10 years.
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| 3. |
- Ahrén, Jonatan, et al.
(author)
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A hypothesis - generating Swedish extended national cross-sectional family study of multimorbidity severity and venous thromboembolism
- 2023
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In: BMJ Open. - 2044-6055. ; 13:6, s. 1-8
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Journal article (peer-reviewed)abstract
- OBJECTIVES: Venous thromboembolism (VTE) is a common worldwide disease. The burden of multimorbidity, that is, two or more chronic diseases, has increased. Whether multimorbidity is associated with VTE risk remains to be studied. Our aim was to determine any association between multimorbidity and VTE and any possible shared familial susceptibility.DESIGN: A nationwide extended cross-sectional hypothesis - generating family study between 1997 and 2015.SETTING: The Swedish Multigeneration Register, the National Patient Register, the Total Population Register and the Swedish cause of death register were linked.PARTICIPANTS: 2 694 442 unique individuals were analysed for VTE and multimorbidity.MAIN OUTCOMES AND MEASURES: Multimorbidity was determined by a counting method using 45 non-communicable diseases. Multimorbidity was defined by the occurrence of ≥2 diseases. A multimorbidity score was constructed defined by 0, 1, 2, 3, 4 or 5 or more diseases.RESULTS: Sixteen percent (n=440 742) of the study population was multimorbid. Of the multimorbid patients, 58% were females. There was an association between multimorbidity and VTE. The adjusted odds ratio (OR) for VTE in individuals with multimorbidity (2 ≥ diagnoses) was 3.16 (95% CI: 3.06 to 3.27) compared with individuals without multimorbidity. There was an association between number of diseases and VTE. The adjusted OR was 1.94 (95% CI: 1.86 to 2.02) for one disease, 2.93 (95% CI: 2.80 to 3.08) for two diseases, 4.07 (95% CI: 3.85 to 4.31) for three diseases, 5.46 (95% CI: 5.10 to 5.85) for four diseases and 9.08 (95% CI: 8.56 to 9.64) for 5 ≥ diseases. The association between multimorbidity and VTE was stronger in males OR 3.45 (3.29 to 3.62) than in females OR 2.91 (2.77 to 3.04). There were significant but mostly weak familial associations between multimorbidity in relatives and VTE.CONCLUSIONS: Increasing multimorbidity exhibits a strong and increasing association with VTE. Familial associations suggest a weak shared familial susceptibility. The association between multimorbidity and VTE suggests that future cohort studies where multimorbidity is used to predict VTE might be worthwhile.
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| 4. |
- Ahrén, Jonatan, et al.
(author)
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Multimorbidity disease clusters are associated with venous thromboembolism : an extended cross-sectional national study
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In: Journal of Thrombosis and Thrombolysis. - 0929-5305.
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Journal article (peer-reviewed)abstract
- Multimorbidity, i.e., two or more non-communicable diseases (NCDs), is an escalating challenge for society. Venous thromboembolism (VTE) is a common cardiovascular disease and it is unknown which multimorbidity clusters associates with VTE. Our aim was to examine the association between different common disease clusters of multimorbidity and VTE. The study is an extended (1997–2015) cross-sectional Swedish study using the National Patient Register and the Multigeneration Register. A total of 2,694,442 Swedish-born individuals were included in the study. Multimorbidity was defined by 45 NCDs. A principal component analysis (PCA) identified multimorbidity disease clusters. Odds ratios (OR) for VTE were calculated for the different multimorbidity disease clusters. There were 16% (n = 440,742) of multimorbid individuals in the study population. Forty-four of the individual 45 NCDs were associated with VTE. The PCA analysis identified nine multimorbidity disease clusters, F1-F9. Seven of these multimorbidity clusters were associated with VTE. The adjusted OR for VTE in the multimorbid patients was for the first three clusters: F1 (cardiometabolic diseases) 3.44 (95%CI 3.24–3.65), F2 (mental disorders) 2.25 (95%CI 2.14–2.37) and F3 (digestive system diseases) 4.35 (95%CI 3.63–5.22). There was an association between multimorbidity severity and OR for VTE. For instance, the occurrence of at least five diseases was in F1 and F2 associated with ORs for VTE: 8.17 (95%CI 6.32–10.55) and 6.31 (95%CI 4.34–9.17), respectively. In this nationwide study we have shown a strong association between VTE and different multimorbidity disease clusters that might be useful for VTE prediction. Graphical abstract: (Figure presented.)
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| 5. |
- Ali, Md Panna, et al.
(author)
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Farmer's behavior in pesticide use : Insights study from smallholder and intensive agricultural farms in Bangladesh
- 2020
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 747
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Journal article (peer-reviewed)abstract
- Since independence and over the years, pesticides have become a dominant feature of Bangladesh agriculture. To protect farmers' health, environment and to improve sustainability of chemical pest control quantitative understanding of farmers' behavior in pesticide use is critical. However, study on the levels of knowledge and awareness of farmers and the practices of pesticide use are often limited. We conducted a broad analysis on the effects of knowledge and awareness of farmers as well as the influence of the different associated stakeholders such as pesticide retailers and the government, on farmers' behavior in pesticide use from a detailed survey of 917 agricultural households in different regions of Bangladesh. Within eight protective behaviors (PBs) or PPEs were largely influenced by the crops growers and regions. Never discarding empty pesticide containers in the field, never applying pesticides more than prescribed by DAE or the instruction manual, selecting new types of pesticides recommended by DAE and purchasing low toxicity pesticides were the most adopted practices. Most farmers from the South-East region were adopting the PB of wearing mask, gloves and long sleeved clothes when spraying and farmers from South trusted the recommendations of pesticides by village leaders and neighbors. Majority of vegetables growers were well informed that pesticides were very harmful to the quality of agricultural products, the environment, and human health but not rice or mixed crops growers. Generally, PBs were positively affected by the perception of the consequences of farmers' behavior and knowledge of pesticide use but negatively influenced by action of governments and trust of retailers. It is important to recognize the differences that exist among different crops growers and locations. Attempt needs to bridge the gap among crop growers, locations and different stakeholder such as government agencies and retailers to develop policy.
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| 6. |
- Almasri, Abdullah, et al.
(author)
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Impact of the periodicity and trend on the FD parameter estimation
- 2007
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In: Journal of Statistical Computation and Simulation. - : Informa UK Limited. - 1563-5163 .- 0094-9655. ; 77:1, s. 79-87
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Journal article (peer-reviewed)abstract
- It is well known that one of the features of long-memory processes is that they tend to have what looks like trends and cycles. A consequence of this property is that it is difficult to distinguish a long-memory process from a nonstationary process. In this paper, we study the impact of the periodicity and trend on different methods for estimating the long-memory processes parameter d.
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| 9. |
- Bergman, Jakob, et al.
(author)
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A measure of dependence between two compositions
- 2012
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In: Australian & New Zealand Journal of Statistics. - 1467-842X. ; 54:4, s. 451-461
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Journal article (peer-reviewed)abstract
- We consider the problem of describing the correlation between two compositions. Using a bicompositional Dirichlet distribution, we calculate a joint correlation coefficient, based on the concept of information gain, between two compositions. Numerical values of the joint correlation coefficient are calculated for compositions of two and three components. We also present an estimator of the joint correlation coefficient for a sample from a bicompositional Dirichlet distribution. Two confidence intervals are also presented and we examine their empirical confidence coefficient using Monte Carlo study. Finally we apply the estimator to a data set analysing the correlation between the 1967 and 1997, and the 1977 and 1997 compositions of the government gross domestic product for the 50 U.S. states and District of Columbia.
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| 10. |
- Bergman, Jakob, et al.
(author)
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A measure of dependence between two compositions
- 2009
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Other publication (other academic/artistic)abstract
- A composition is a vector of positive components summing to a constant. We consider the problem of describing the correlation between two compo- sitions. Using a bicompositional Dirichlet distribution, we calculate a joint correlation coefficient, based on the concept of information gain, between two compositions. Numerical values of the joint correlation coefficient are calcu- lated for compositions of two and three components.
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| 11. |
- Bergman, Jakob, et al.
(author)
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Are the Sweden Democrats really Sweden’s largest party? A maximum likelihood ratio test on the simplex
- 2015
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Other publication (other academic/artistic)abstract
- In August 2015 a Swedish newspaper claimed that the Sweden Democrats were the largest political party in Sweden based on the results of single poll. We ask ourselves if this is a correct conclusion, considering the fact that the three largest parties in the poll were of roughly the same size. We analyse the parameter space and identify the subspace where the Sweden Democrats are the largest party. Using this we construct a maximum likelihood ratio test and derive its distribution under the null hypothesis. We finally apply our test to the data and obtaining a p-value between 0.09 and 0.14 are able to refute the claim in the newspaper. Based on the available data one cannot draw the conclusion that the Sweden Democrats are the largest party in Sweden.
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| 12. |
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| 13. |
- Bergman, Jakob, et al.
(author)
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Compositional Loess modeling
- 2011
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In: Proceedings of the 4th International Workshop on Compositional Data Analysis. - 9788487867767
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Conference paper (other academic/artistic)abstract
- Cleveland (1979) is usually credited with the introduction of the locally weighted regression, Loess. The concept was further developed by Cleveland and Devlin (1988). The general idea is that for an arbitrary number of explanatory data points xi the value of a dependent variable is estimated ŷi. The ŷi is the fitted value from a dth degree polynomial in xi. (In practice often d = 1.) The ŷi is fitted using weighted least squares, WLS, where the points xk (k = 1, ..., n) closest to xi are given the largest weights. We define a weighted least squares estimation for compositional data, C-WLS. In WLS the sum of the weighted squared Euclidean distances between the observed and the estimated values is minimized. In C-WLS we minimize the weighted sum of the squared simplicial distances (Aitchison, 1986, p. 193) between the observed compositions and their estimates. We then define a compositional locally weighted regression, C-Loess. Here a composition is assumed to be explained by a real valued (multivariate) variable. For an arbitrary number of data points xi we for each xi fit a dth degree polynomial in xi yielding an estimate ŷi of the composition yi. We use C-WLS to fit the polynomial giving the largest weights to the points xk (k = 1, ..., n) closest to xi. Finally the C-Loess is applied to Swedish opinion poll data to create a poll-of-polls time series. The results are compared to previous results not acknowledging the compositional structure of the data.
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| 14. |
- Bergman, Jakob, et al.
(author)
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Poll of polls: A compositional loess model
- 2014
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In: Scandinavian Journal of Statistics. - : Wiley. - 1467-9469 .- 0303-6898. ; 41:2, s. 301-310
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Journal article (peer-reviewed)abstract
- A large number of polls on party preferences are published today. In order to get an estimate of the changes in political opinion, the polls may be combined into a poll of polls. We discuss a method for combining polls using the fact that they are compositions and respecting the properties of the compositional sample space (the simplex). The method is easily implemented and the estimate may be computed in linear time. We provide an example with Swedish data from year 2007 to 2010. The method also allows us to present the deviations between the estimated compositions and the observed. In the data set, we note e.g. differences between different polling institutes.
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| 15. |
- Bergman, Jakob, et al.
(author)
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Är SD Sveriges största parti?
- 2016
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In: Symposium i anvendt statistik. - 9788750122104 ; , s. 95-99
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Conference paper (other academic/artistic)abstract
- Den 20 augusti 2015 hävdade dagstidningen Metro att Sverigedemokraterna var Sveriges största parti. Detta baserade man på att partiet blivit det största i en opinions-undersökning av företaget YouGov. Men hur kan man testa påståendet att en specifik andel är den största? Vi tar vår utgångspunkt i andelarnas speciella parameterrum simplex och dess inbyggda restriktioner. Vi visar hur man kan konstruera ett test för att avgöra om en specifik andel är störst baserat på en likelihoodkvotansats, där vi utnyttjar en isometrisk logkvotstransformation för att underlätta de numeriska beräkningarna. Eftersom man vid denna typ av problem typiskt enbart har en enda observation av de relativa partipreferenser, diskuterar vi teststorhetens fördelning. Vi illustrerar våra resonemang med data från den ovan nämnda undersökningen av YouGov.
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| 16. |
- Björck, Svante, et al.
(author)
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A magnetostratigraphic comparison between 14C years and varve years during the late Weichselian, indicating significant differences between the time-scales
- 1987
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In: Journal of Quaternary Science. - : Wiley. - 1099-1417 .- 0267-8179. ; 2:2, s. 133-140
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Journal article (peer-reviewed)abstract
- A 14C-dated magnetostratigraphy of absolute declination and inclination between 12500 and 10000 14C yr BP was recently developed for southern Sweden. Recently also the Swedish geochronological time-scale, based on c. 11 500 annually deposited clay-varves, was connected with the present. It should therefore be possible to compare the two chronologies with a reliable magnetostratigraphic record in an appropriate clay-varve section. We have found such a site within the Middle Swedish end-moraine zone. Statistical correlations between the two independently dated time-scales suggest that at 10500–10200 14Cy r BP the varve chronology exceeds the 14C chronology by the order of 500-600 varve yr. Other correlations indicate that the difference between the two chronologies was less at 11000 14C yr BP, and further correlations between the time-scales at 12000 14C yr BP suggest that the difference between the chronologies increased steadily from 12000 to 10000 14C yr BP. If these correlations are correct they imply that the 14C production rate increased steadily during the Late Weichselian.
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| 20. |
- Djurfeldt, Göran, et al.
(author)
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African farm dynamics and the sub-continental food crisis – the case of maize
- 2008
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In: Acta Agriculturae Scandinavica. Section C. Food Economics. - : Informa UK Limited. - 1650-7541 .- 1651-288X. ; 5:2, s. 75-91
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Journal article (peer-reviewed)abstract
- This is a longitudinal study of smallholder farm dynamics in eight African countries, drawing on a sample of more than 3000 farm households. It deals with influences on smallholder maize production at three different levels: micro, meso and macro. Although the study points to inadequately exploited production potentials and a production system based primarily on self-provisioning the drivers behind dynamism in this context are clear. Dynamic production patterns are closely associated with smallholder access to modern crop technologies in combination with commercial incentives as expressed both at the meso and macro levels.
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| 21. |
- Djurfeldt, Göran, et al.
(author)
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Afrint database
- 2011
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Other publication (other academic/artistic)
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| 22. |
- Djurfeldt, Göran, et al.
(author)
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Using panel survey and remote sensing data to explain yield gaps for maize in sub-Saharan Africa
- 2018
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In: Journal of Land Use Science. - 1747-423X. ; 13:3, s. 344-357
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Journal article (peer-reviewed)abstract
- The aim of this paper is to combine remote sensing data with geo-coded household survey data in order to measure the impact of different socio-economic and biophysical factors on maize yields. We use multilevel linear regression to model village mean maize yield per year as a function of NDVI, commercialization, pluriactivity and distance to market. We draw on seven years of panel data on African smallholders, drawn from three rounds of data collection over a twelve-year period and 56 villages in six countries combined with a time-series analysis of NDVI data from the MODIS sensor. We show that, although there is much noise in yield forecasts as made with our methodology, socio-economic drivers substantially impact on yields, more, it seems, than do biophysical drivers. To reach more powerful explanations researchers need to incorporate socio-economic parameters in their models.
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| 23. |
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| 25. |
- Gustafsson, Ny Björn, 1975-
(author)
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Casting Identities in Central Seclusion : Aspects of non-ferrous metalworking and society on Gotland in the Early Medieval Period
- 2013
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Doctoral thesis (other academic/artistic)abstract
- The aim of this thesis has been to investigate and interpret late Iron Ageand Early Medieval traces of non-ferrous metalworking on the islandGotland, Sweden. Gotland was not, based on the archaeological record, anintegrated part of the common Scandinavian culture. Instead a local,endemic cultural expression had developed; a seclusion which lasted forcenturies despite the islands central position in the Baltic Sea. In thepast, key elements for the understanding of local settlement- and burialpractices as well as the local material culture were mainly recovered andreported by local farmers. A specific category of such finds – so-called‘bronze slag’ is discussed and partly reinterpreted in the first study ofthis thesis. Two further studies treat different aspects of metalworkingand metalworkers – one discusses common archaeological notions ofScandinavian workshops, production sites and metalworkers from a criticalperspective while the other mainly focuses on the Gotlandic finds frommetal-detector surveys carried out over the last 35 years. Based on whereand to which extent, both from a quantitative and a qualitative point ofview, these finds occur a hierarchical classification into four sub groupsis presented – ordinary farm sites with traces of non-ferrous metalworking,workshop sites, potential workshop sites and last, extrovert harboursettlements. A fourth study presents an attempt to evaluate the usefulnessof magnetometry in delimiting extant traces of high-temperature crafts,such as metalworking. The last study of the thesis presents an attempt touse trace elements analysis of skeletal lead in human bone to identifypotential non-ferrous metalworkers.As the wearing of endemic Gotlandic jewellery appears to have been centralin the manifestation of the local identity it is argued that themetalworking artisans played a crucial role in defining how this identitywas signalled and displayed via the jewellery and dress-related metalobjects. It is further suggested that these artisans might have played animportant role in upholding the local economy before the advent of localminting.
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