A law of large numbers approximation for Markov population processes with countably many types

When modelling metapopulation dynamics, the influence of a single patch on the metapopulation depends on the number of individuals in the patch. Since the population size has no natural upper limit, this leads to systems in which there are countably infinitely many possible types of individual. Analogous considerations apply in the transmission of parasitic diseases. In this paper, we prove a law of large numbers for rather general systems of this kind, together with a rather sharp bound on the rate of convergence in an appropriately chosen weighted $\ell_1$ norm.Comment: revised version in response to referee comments, 34 page

History of vascular disease and mild parkinsonian signs in community-dwelling elderly individuals

Background: Mild parkinsonian signs (MPS) are commonly found during the clinical examination of older people. These signs could reflect the accumulation of vascular pathological changes in the brain. If the etiology were vascular, one could hypothesize that individuals with MPS would be more likely to have systemic vascular disease than would their counterparts without these signs. Objectives: To examine whether MPS are associated with a history of vascular disease and whether certain MPS (rigidity, changes in axial function) are more strongly associated with a history of vascular disease than are other MPS (tremor). Methods: Evaluation of older people without dementia in Washington Heights-Inwood, northern Manhattan, NY. The presence of vascular diseases was assessed with a structured health interview. Results: Mild parkinsonian signs were present in 375 (16.4%) of 2286 participants without dementia. Diabetes mellitus, heart disease, peripheral vascular disease, and stroke were more prevalent in participants with MPS than without MPS, whereas nonvascular diseases (cancer, thyroid disease) were not. In a logistic regression analysis that adjusted for age, sex, education, and depressive symptoms, the number of vascular diseases was associated with MPS (odds ratio, 1.31 [95% confidence interval, 1.18-1.46]; P<.001). The combination of diabetes mellitus and heart disease increased the odds of MPS by 70% and the combination of these with stroke increased the odds by 332%. Conclusions: The presence of MPS in elderly individuals might reflect, in part, the accumulation of vascular pathological changes in the basal ganglia or white matter regions caused by preventable vascular diseases. Prospective and pathological studies are needed to further explore this finding

DESIGN TOOLS FOR INFLATABLE STRUCTURES

This paper shows different tools and approaches that can be useful for the definition of the design of pneumatic structures. Some of these tools have been applied for the design of a Tensairity® hull

Mediterranean Diet, Inflammatory and Metabolic Biomarkers, and Risk of Alzheimer's Disease

We aimed to investigate the association between adherence to the Mediterranean diet (MeDi) and Alzheimer's disease (AD) risk in a prospective study. Specifically, we analyzed reduced inflammation and improved metabolic profile as a potential medium through which the MeDi reduced the risk of AD. During a 4-year follow-up, 118 incident AD cases were identified among the 1219 non-demented elderly (age ⩾ 65) subjects who provided dietary information and blood samples at baseline. We used high-sensitivity C-reactive protein (hsCRP) as an index of systemic inflammation, and fasting insulin and adiponectin as indexes of metabolic profile. We investigated whether there was a change in the association between MeDi and incident AD risk when the biomarkers were introduced into multivariable adjusted COX models. Better adherence to MeDi was associated with lower level of hsCRP (p =0.003), but not fasting insulin or adiponectin. Better adherence to MeDi was significantly associated with lower risk for AD: compared to those in the lowest tertile of MeDi, subjects in the highest tertile had a 34% less risk of developing AD (p-for-trend =0.04). Introduction of the hsCRP, fasting insulin, adiponectin, or combinations of them into the COX model did not change the magnitude of the association between MeDi and incident AD. Ultimately, the favorable association between better adherence to MeDi and lower risk of AD did not seem to be mediated by hsCRP, fasting insulin, or adiponectin. Other aspects of inflammatory and metabolic pathways not captured by these biomarkers, or non-inflammatory or non-metabolic pathways, may be relevant to the MeDi-AD association

A CULTURAL METHOD OF REDUCING POCKET GOPHER IMPACT ON ALFALFA YIELD

Low Input Sustainable Agriculture (LISA) strives to minimize input of agrichemicals for farmers while maintaining profits. Alfalfa fits into this scheme in 2 ways. First, the plains pocket gophers (Geomys bursarius) can reduce yield of alfalfa, thus an effective, economical means of control with minimal environmental impact would be desirable. Second, the increased use of alfalfa in rotation with row crops to increase soil nitrogen may increase pocket gopher problems by increasing their habitat. Our objective was to evaluate a cultural method to control pocket gopher damage, namely, by comparing 2 different varieties of alfalfa. One variety is tap-rooted (Wrangler) while the other has a more fibrous-rooted system (Spredor 2). We hypothesized that damage would be less in the fibrous-rooted alfalfa as it is capable of vegetative reproduction and could recolonize areas. We released live-trapped pocket gophers on 4 treatment areas in each alfalfa variety. Pocket gophers were present on plots of each variety from the fall of 1988 through the fall of 1989. Damage caused by pocket gophers was measured by clipping 80 samples/harvest during the 1989 growing season. Yields were 15 to 19% less in treatment areas than in control areas for both varieties. Sampling continued through the 1990 growing season to determine the recovery rate of each variety after gophers had been removed. The tap-rooted variety showed no improvement in 1990 over 1989. On the other hand, the fibrous-rooted alfalfa exhibited a 4% increase in treatment over control areas after gopher removal