How specialised must natural enemies be to facilitate coexistence among plants?

The Janzen‐Connell hypothesis proposes that plant interactions with host‐specific antagonists can impair the fitness of locally abundant species and thereby facilitate coexistence. However, insects and pathogens that associate with multiple hosts may mediate exclusion rather than coexistence. We employ a simulation model to examine the effect of enemy host breadth on plant species richness and defence community structure, and to assess expected diversity maintenance in example systems. Only models in which plant enemy similarity declines rapidly with defence similarity support greater species richness than models of neutral drift. In contrast, a wide range of enemy host breadths result in spatial dispersion of defence traits, at both landscape and local scales, indicating that enemy‐mediated competition may increase defence‐trait diversity without enhancing species richness. Nevertheless, insect and pathogen host associations in Panama and Papua New Guinea demonstrate a potential to enhance plant species richness and defence‐trait diversity comparable to strictly specialised enemies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99082/1/ele12130.pd

Study of capillary-based gaseous detectors

We have studied gain vs. voltage characteristics and position resolutions of multistep capillary plates (two or three capillary plates operating in a cascade), as well as capillary plates operating in a mode when the main amplification occurs between plates or between the capillary plate and the readout plate (parallel plate amplification mode). Results of these studies demonstrated that in the parallel-plate amplification mode one can reach both high gains (>100000) and good position resolutions (~100 micro meter) even with a single step arrangement. It offers a compact amplification structure, which can be used in many applications. For example, in preliminary tests we succeeded to combine it with a photocathode and use it as a position sensitive gaseous photomultiplier. CsI coated capillary plates could also be used as a high position resolution and high rate X-ray converter.Comment: Presented at the NSS IEEE 2003 conference in Portland, submitted to TN

Calcium supplementation and risk of dementia in women with cerebrovascular disease

OBJECTIVE: To determine whether calcium supplementation is associated with the development of dementia in women after a 5-year follow-up. METHODS: This was a longitudinal population-based study. The sample was derived from the Prospective Population Study of Women and H70 Birth Cohort Study in Gothenburg, Sweden, and included 700 dementia-free women aged 70–92 years. At baseline in 2000–2001, and at follow-up in 2005–2006, the women underwent comprehensive neuropsychiatric and somatic examinations. A CT scan was performed in 447 participants at baseline. Information on the use and dosage of calcium supplements was collected. Dementia was diagnosed according to DSM-III-R criteria. RESULTS: Women treated with calcium supplements (n = 98) were at a higher risk of developing dementia (odds ratio [OR] 2.10, 95% confidence interval [CI] 1.01–4.37, p = 0.046) and the subtype stroke-related dementia (vascular dementia and mixed dementia) (OR 4.40, 95% CI 1.54–12.61, p = 0.006) than women not given supplementation (n = 602). In stratified analyses, calcium supplementation was associated with the development of dementia in groups with a history of stroke (OR 6.77, 95% CI 1.36–33.75, p = 0.020) or presence of white matter lesions (OR 2.99, 95% CI 1.28–6.96, p = 0.011), but not in groups without these conditions. CONCLUSIONS: Calcium supplementation may increase the risk of developing dementia in elderly women with cerebrovascular disease. Because our sample was relatively small and the study was observational, these findings need to be confirmed

Introducing a true internal standard for the Comet assay to minimize intra- and inter-experiment variability in measures of DNA damage and repair

The Comet assay (CA) is a sensitive/simple measure of genotoxicity. However, many features of CA contribute variability. To minimize these, we have introduced internal standard materials consisting of ‘reference’ cells which have their DNA substituted with BrdU. Using a fluorescent anti-BrdU antibody, plus an additional barrier filter, comets derived from these cells could be readily distinguished from the ‘test’-cell comets, present in the same gel. In experiments to evaluate the reference cell comets as external and internal standards, the reference and test cells were present in separate gels on the same slide or mixed together in the same gel, respectively, before their co-exposure to X-irradiation. Using the reference cell comets as internal standards led to substantial reductions in the coefficient of variation (CoV) for intra- and inter-experimental measures of comet formation and DNA damage repair; only minor reductions in CoV were noted when the reference and test cell comets were in separate gels. These studies indicate that differences between individual gels appreciably contribute to CA variation. Further studies using the reference cells as internal standards allowed greater significance to be obtained between groups of replicate samples. Ultimately, we anticipate that development will deliver robust quality assurance materials for CA

Interface Engineering Routes for a Future CMOS Ge-based Technology

We present an overview study of two germanium interface engineering routes, firstly a germanate formation via La2O3 and Y2O3, and secondly a barrier layer approach using Al2O3 and Tm2O3. The interfacial composition, uniformity, thickness, band gap, crystallinity, absorption features and valence band offset are determined using X-ray photoelectron spectroscopy, ultra violet variable angle spectroscopic ellipsometry, and high resolution transmission electron microscopy. The correlation of these results with electrical characterization data make a case for Ge interface engineering with rare-earth inclusion as a viable route to achieve high performance Ge CMOS.</jats:p

Functional disability and death wishes in older Europeans: results from the EURODEP concerted action

Functional disability was independently associated with death wishes in older adults. Results can help inform clinicians who care for older persons with functional impairment.</p