1,233 research outputs found
Demographic fluctuations in a population of anomalously diffusing individuals
The phenomenon of spatial clustering induced by death and reproduction in a
population of anomalously diffusing individuals is studied analytically. The
possibility of social behaviors affecting the migration strategies has been
taken into exam, in the case anomalous diffusion is produced by means of a
continuous time random walk (CTRW). In the case of independently diffusing
individuals, the dynamics appears to coincide with that of (dying and
reproducing) Brownian walkers. In the strongly social case, the dynamics
coincides with that of non-migrating individuals. In both limits, the growth
rate of the fluctuations becomes independent of the Hurst exponent of the CTRW.
The social behaviors that arise when transport in a population is induced by a
spatial distribution of random traps, have been analyzed.Comment: 10 pages, 6 figure
Ontogenetic differences in the chemical defence of flea beetles influence their predation risk
Decision-Making for Long Memory Data in Technical-Economic Design, Fractals and Decision Area Bubbles
Bovine Leptospirosis in Iowa: A Serological Survey
Bovine leptospirosis is one of the major cattle diseases in the United States causing significant economic losses to the cattle industry. This disease in cattle has been associated with abortion, repeat breeding, still-births, fetal death,s weak calves, and reduced milk production. In the United States, the disease is cause dby infection with one or more of 6 known pathogenic leptospiral serovars: pomona, hardjo, grippotyphosa, canicola, icterohaemorragiae, and szwajizak
Least Squares and Shrinkage Estimation under Bimonotonicity Constraints
In this paper we describe active set type algorithms for minimization of a
smooth function under general order constraints, an important case being
functions on the set of bimonotone r-by-s matrices. These algorithms can be
used, for instance, to estimate a bimonotone regression function via least
squares or (a smooth approximation of) least absolute deviations. Another
application is shrinkage estimation in image denoising or, more generally,
regression problems with two ordinal factors after representing the data in a
suitable basis which is indexed by pairs (i,j) in {1,...,r}x{1,...,s}. Various
numerical examples illustrate our methods
Changes in prevalence and the cascade of care for type 2 diabetes over ten years (2005-2015): results of two nationally representative surveys in Mozambique
Background: Sub-Saharan Africa is predicted to have the steepest increase in the prevalence of diabetes in the next 25 years. The latest Mozambican population-based STEPS survey (STEPS 2005) estimated a 2.9% prevalence of diabetes in the adult population aged 25-64 years. We aimed to assess the change in prevalence, awareness, and management of diabetes in the national STEPS survey from 2014/2015 compared to 2005. Methods: We conducted an observational, quantitative, cross-sectional study following the WHO STEPS surveillance methodology in urban and rural settings, targeting the adult population of Mozambique in 2015. We collected sociodemographic data, anthropometric, and 12 hour fasting glucose blood samples in a sample of 1321 adults. The analysis consisted of descriptive measures of the prevalence of impaired fasting glucose (IFG), diabetes and related risk factors by age group, sex, and urban/rural residence and compared the findings to those of the 2005 survey results. Results: The prevalence of IFG and diabetes was 4.8% (95CI: 3.6-6.3) and 7.4% (95CI: 5.5-10.0), respectively. These prevalence of IFG and diabetes did not differ significantly between women and men. The prevalence of diabetes in participants classified with overweight/obesity [10.6% (95CI: 7.5-14.6)] and with central obesity (waist hip ratio) [11.0% (95CI: 7.4-16.1)] was almost double the prevalence of their leaner counterparts, [6.3% (95CI, 4.0-9.9)] and [5.2% (95CI: 3.2-8.6)], respectively. Diabetes prevalence increased with age. There were 50% more people with diabetes in urban areas than in rural. Only 10% of people with diabetes were aware of their disease, and only 44% of those taking oral glucose-lowering drugs. The prevalence of IFG over time [2.0% (95CI: 1.1-3.5) vs 4.8% (95CI: 3.6-6.3)] and diabetes [2.9% (95CI: 2.0-4.2) vs 7.4% (95CI: 5.5-10.0)] were more than twofold higher in 2014/2015 than in 2005. However, awareness of disease and being on medication decreased by 3% and by 50%, respectively. Though this was not statistically significant. Conclusions: While the prevalence of diabetes in Mozambique has increased from 2005 to 2015, awareness and medication use have declined considerably. There is an urgent need to improve the capacity of primary health care and communities to detect, manage and prevent the occurrence of NCDs and their risk factors. © 2022, The Author(s).The study was supported by the Mozambican Ministry of Health and by the WHO. Additionally, this research forms part of a thesis for a Doctoral degree funded by the COHESION Project financed by the Swiss Agency for Development and Cooperation (SDC) and the Swiss National Science Foundation (SNF), under the funding scheme r4d - Swiss Programme for Research on Global Issues for Development, grant number #160366
Hijacking the mustard-oil bomb: How a glucosinolate-sequestering flea beetle copes with plant myrosinases
Myrosinase enzymes play a key role in the chemical defense of plants of the order Brassicales. Upon herbivory, myrosinases hydrolyze the β-S-linked glucose moiety of glucosinolates, the characteristic secondary metabolites of brassicaceous plants, which leads to the formation of different toxic hydrolysis products. The specialist flea beetle, Phyllotreta armoraciae, is capable of accumulating high levels of glucosinolates in the body and can thus at least partially avoid plant myrosinase activity. In feeding experiments with the myrosinase-deficient Arabidopsis thaliana tgg1 × tgg2 (tgg) mutant and the corresponding Arabidopsis Col-0 wild type, we investigated the influence of plant myrosinase activity on the metabolic fate of ingested glucosinolates in adult P. armoraciae beetles. Arabidopsis myrosinases hydrolyzed a fraction of ingested glucosinolates and thereby reduced the glucosinolate sequestration rate by up to 50% in adult beetles. These results show that P. armoraciae cannot fully prevent glucosinolate hydrolysis; however, the exposure of adult beetles to glucosinolate hydrolysis products had no impact on the beetle’s energy budget under our experimental conditions. To understand how P. armoraciae can partially prevent glucosinolate hydrolysis, we analyzed the short-term fate of ingested glucosinolates and found them to be rapidly absorbed from the gut. In addition, we determined the fate of ingested Arabidopsis myrosinase enzymes in P. armoraciae. Although we detected Arabidopsis myrosinase protein in the feces, we found only traces of myrosinase activity, suggesting that P. armoraciae can inactivate plant myrosinases in the gut. Based on our findings, we propose that the ability to tolerate plant myrosinase activity and a fast glucosinolate uptake mechanism represent key adaptations of P. armoraciae to their brassicaceous host plants
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