Edith Cowan University

About: Edith Cowan University is a education organization based out in Perth, Western Australia, Australia. It is known for research contribution in the topics: Population & Context (language use). The organization has 4040 authors who have published 13529 publications receiving 339582 citations. The organization is also known as: Edith Cowan & ECU.

Longitudinal Assessment of Aβ and Cognition in Aging and Alzheimer Disease

Abstract: In vivo amyloid imaging with positron emission tomography (PET) allows longitudinal study of Aβ deposition in an individual and should provide unique information on the relationship between Aβ and cognitive decline. Although it is likely that Aβ plays a fundamental role in the development of dementia of the Alzheimer type (DAT),1 postmortem studies have not consistently demonstrated a relationship between the density of amyloid plaques and the severity of dementia.2–5 The time course of plaque formation is unclear. Studies comparing the plaque density at brain biopsy in DAT patients to that assessed in those same patients at postmortem several years later found little change in the majority of patients, but these studies had few participants.6–9 An additional perplexing postmortem observation is the high prevalence of amyloid plaques in the normal elderly. It has been postulated that this represents preclinical DAT, but this cannot be proven by autopsy-based studies. In vivo Aβ imaging provides the means to address these questions through longitudinal observation. Cross-sectional [11C]Pittsburgh compound B (PiB) PET studies have shown a robust difference between the retention patterns in DAT patients and healthy controls (HCs).10,11 In agreement with postmortem data,2 approximately 20 to 30% of elderly HC subjects show some degree of increased cortical PiB retention, predominantly in the prefrontal cortex and posterior cingulate/precuneus areas.10,12–14 Polymorphism of the apolipoprotein E (ApoE) allele is among the most consistent genetic risk factors associated with sporadic DAT, and its presence is thought to result in an earlier age of onset.15,16 Examination of ApoE e4 allele status revealed that healthy e4 carriers present with significantly higher PiB retention than e4 noncarriers and show increased retention at an earlier age, further emphasizing the crucial role that ApoE plays in the metabolism of Aβ.10,17–20 Recently, several studies have found significant increases in PiB retention in some individuals over 1 to 2 years, but no overall increase in mean PiB retention in groups of subjects with DAT or mild cognitive impairment (MCI). These studies did report a higher conversion rate from MCI to DAT in those with high PiB retention, despite a lack of significant change in PiB retention in those who progressed.21–24 The objectives of this study were to quantify the progression of Aβ plaque formation in the brain over time with PiB PET in a large number of individuals and to correlate Aβ plaque burden at baseline and follow-up with clinical measures of disease severity, cognitive decline, and ApoE status.

Global patterns of foliar nitrogen isotopes and their relationships with climate, mycorrhizal fungi, foliar nutrient concentrations, and nitrogen availability

Abstract: Ratios of nitrogen (N) isotopes in leaves could elucidate underlying patterns of N cycling across ecological gradients. To better understand global-scale patterns of N cycling, we compiled data on foliar N isotope ratios (delta(15)N), foliar N concentrations, mycorrhizal type and climate for over 11,000 plants worldwide. Arbuscular mycorrhizal, ectomycorrhizal, and ericoid mycorrhizal plants were depleted in foliar delta(15)N by 2 per thousand, 3.2 per thousand, 5.9 per thousand, respectively, relative to nonmycorrhizal plants. Foliar delta(15)N increased with decreasing mean annual precipitation and with increasing mean annual temperature (MAT) across sites with MAT >or= -0.5 degrees C, but was invariant with MAT across sites with MAT < -0.5 degrees C. In independent landscape-level to regional-level studies, foliar delta(15)N increased with increasing N availability; at the global scale, foliar delta(15)N increased with increasing foliar N concentrations and decreasing foliar phosphorus (P) concentrations. Together, these results suggest that warm, dry ecosystems have the highest N availability, while plants with high N concentrations, on average, occupy sites with higher N availability than plants with low N concentrations. Global-scale comparisons of other components of the N cycle are still required for better mechanistic understanding of the determinants of variation in foliar delta(15)N and ultimately global patterns in N cycling.

Cyberbullying Versus Face-to-Face Bullying A Theoretical and Conceptual Review

Abstract: Cyberbullying has been described as a type of electronic bullying and has recently been subjected to intense media scrutiny largely due to a number of high profile and tragic cases of teen suicide. Despite the media attention relatively little is known about the nature of cyberbullying. This is, at least in part, due to a lack of theoretical and conceptual clarity and an examination of the similarities and differences between cyberbullying and face-to-face bullying. This paper reviews the limited theoretical and empirical literature addressing both cyberbullying and face-to-face bullying, using some specific examples from a qualitative study for illustration. We compare and contrast individual factors common to cyber and face-to-face bullying. We then examine social information processing factors associated with face-to-face bullying and present a discussion of the similarities and differences that may characterize cyberbullying.

Marine heatwaves threaten global biodiversity and the provision of ecosystem services

Abstract: The global ocean has warmed substantially over the past century, with far-reaching implications for marine ecosystems. Concurrent with long-term persistent warming, discrete periods of extreme regional ocean warming (marine heatwaves, MHWs) have increased in frequency. Here we quantify trends and attributes of MHWs across all ocean basins and examine their biological impacts from species to ecosystems. Multiple regions in the Pacific, Atlantic and Indian Oceans are particularly vulnerable to MHW intensification, due to the co-existence of high levels of biodiversity, a prevalence of species found at their warm range edges or concurrent non-climatic human impacts. The physical attributes of prominent MHWs varied considerably, but all had deleterious impacts across a range of biological processes and taxa, including critical foundation species (corals, seagrasses and kelps). MHWs, which will probably intensify with anthropogenic climate change, are rapidly emerging as forceful agents of disturbance with the capacity to restructure entire ecosystems and disrupt the provision of ecological goods and services in coming decades.

The Australian Imaging, Biomarkers and Lifestyle (AIBL) study of aging: Methodology and baseline characteristics of 1112 individuals recruited for a longitudinal study of Alzheimer's disease

Abstract: Background: The Australian Imaging, Biomarkers and Lifestyle (AIBL) flagship study of aging aimed to recruit 1000 individuals aged over 60 to assist with prospective research into Alzheimer's disease (AD). This paper describes the recruitment of the cohort and gives information about the study methodology, baseline demography, diagnoses, medical comorbidities, medication use, and cognitive function of the participants. Methods: Volunteers underwent a screening interview, had comprehensive cognitive testing, gave 80 ml of blood, and completed health and lifestyle questionnaires. One quarter of the sample also underwent amyloid PET brain imaging with Pittsburgh compound B (PiB PET) and MRI brain imaging, and a subgroup of 10% had ActiGraph activity monitoring and body composition scanning. Results: A total of 1166 volunteers were recruited, 54 of whom were excluded from further study due to comorbid disorders which could affect cognition or because of withdrawal of consent. Participants with AD (211) had neuropsychological profiles which were consistent with AD, and were more impaired than participants with mild cognitive impairment (133) or healthy controls (768), who performed within expected norms for age on neuropsychological testing. PiB PET scans were performed on 287 participants, 100 had DEXA scans and 91 participated in ActiGraph monitoring. Conclusion: The participants comprising the AIBL cohort represent a group of highly motivated and well- characterized individuals who represent a unique resource for the study of AD. They will be reassessed at 18-month intervals in order to determine the predictive utility of various biomarkers, cognitive parameters and lifestyle factors as indicators of AD, and as predictors of future cognitive decline.