Differential effects of aging on spatial learning through exploratory navigation and map reading

It has been shown that abilities in spatial learning and memory are adversely affected by aging. The present study was conducted to investigate whether increasing age has equal consequences for all types of spatial learning or impacts certain types of spatial learning selectively. Specifically, two major types of spatial learning, exploratory navigation and map reading, were contrasted. By combining a neuroimaging finding that the medial temporal lobe (MTL) is especially important for exploratory navigation and a neurological finding that the MTL is susceptible to age-related atrophy, it was hypothesized that spatial learning through exploratory navigation would exhibit a greater decline in later life than spatial learning through map reading. In an experiment, young and senior participants learned locations of landmarks in virtual environments either by navigating in them in the first-person perspective or by seeing aerial views of the environments. Results showed that senior participants acquired less accurate memories of the layouts of landmarks than young participants when they navigated in the environments, but the two groups did not differ in spatial learning performance when they viewed the environments from the aerial perspective. These results suggest that spatial learning through exploratory navigation is particularly vulnerable to adverse effects of aging, whereas elderly adults may be able to maintain their map reading skills relatively well.

Predictors of mental health in midlife and older women : results from the Australian Healthy Aging of Women Study

Purpose: To examine the extent to which socio-demographic characteristics, modifiable lifestyle factors and health status influence the mental health of midlife and older Australian women from the Australian Healthy Aging of Women (HOW) study. Methods: Data on health status, chronic disease and modifiable lifestyle factors were collected from a random sample of 340 women aged 40-65 years, residing in Queensland, Australia in 2011. Structural equation modelling (SEM) was used to measure the effect of a range of socio-demographic characteristics (marital status, age, income), modifiable lifestyle factors (caffeine intake, alcohol consumption, exercise, physical activity, sleep), and health markers (self-reported physical health, history of chronic illness) on the latent construct, mental health. Mental health was evaluated using the Medical Outcomes Study Short Form 12 (SF-12®) and the Center for Epidemiologic Studies Depression Scale (CES-D). Results: The model was a good fit for the data (χ2 = 40.166, df =312, p 0.125, CFI = 0.976, TLI = 0.950, RMSEA = 0.030, 90% CI = 0.000-0.053); the model suggested mental health was negatively influenced by sleep disturbance (β = -0.628), sedentary lifestyle (β = -0.137), having been diagnosed with one or more chronic illnesses (β = -0.203), and poor self-reported physical health (β = - 0.161). While mental health was associated with sleep, it was not correlated with many other lifestyle factors (BMI (β = -0.050), alcohol consumption (β = 0.079), or cigarette smoking (β = 0.008)) or background socio-demographic characteristics (age (β = 0.078), or income (β = -0.039)). Conclusion: While research suggests that it is important to engage in a range health promoting behaviours to preserve good health, we found that only sleep disturbance, physical health, chronic illness and level of physical activity predicted current mental health. However, while socio-demographic characteristics and modifiable lifestyle factors seemed to have little direct impact on mental health, they probably had an indirect effect.

What predicts mental health in midlife and older women? Results from the Australian Healthy Aging of Women Study

Objectives: Previous research has linked unhealthy lifestyle with a range of negative health outcomes in women. As women age however, they may have fewer performance expectations, but may view their health more positively. Clearly, the experiences of midlife and older women in relation to health and wellbeing need further exploration. The purpose of this study is to examine the factors associated with poor health-related quality of life in midlife (HRQoL) and older Australian women. Methods: The Australian longitudinal Healthy Aging of Women (HOW) study prospectively examines HRQoL, chronic disease and modifiable lifestyle factors midlife and older women as they age. Random sampling was used to select rural and urban based women from South-East Queensland, Australia. Data were collected from 386 women at three time points over the last decade (2001, 2004 and 2011). Results: The average age of women in this study was 65 years (SD = 2.82). Almost three-quarters (73%, n = 248) of the sample were married or living as though married, nine per cent (n = 30) were separated or divorced and a small proportion were had never married (n = 13). Most (86%, n = 291) of the women sample reported being Australian born, around one quarter (34%, n = 114) had completed additional study since leaving school (university degree or diploma). Over half (55%, n = 186) of participants were retired, one quarter (25%, n = 85) were in paid employment and the remained were unemployed (1%, n = 4), unable to work because of illness (2%, n = 6) or worked within the home (17%, n = 56). Using data collected over time we examined the relationship between a range of modifiable lifestyle factors and mental health using structural equation modelling. The overall model exhibited a good fit with the data. Poor sleep quality was associated with reduced mental health while better mental health was reported in women who exercised regularly and satisfied with their currently weight. As hypothesized, past mental health was a significant mediator of current mental health. Conclusions: These findings demonstrate that the mental health of women is complex and needs to be understood not only in terms of current lifestyle but also in relation to previously reported health status.

Active aging: Exploration into self-ratings of "being active," out-of-home physical activity, and participation among older Australian adults living in four different settings

We examined whether self-ratings of “being active” among older people living in four different settings (major city high and lower density suburbs, a regional city, and a rural area) were associated with out-of-home participation and outdoor physical activity. A mixed-methods approach (survey, travel diary, and GPS tracking over a one-week period) was used to gather data from 48 individuals aged over 55 years. Self-ratings of “being active” were found to be positively correlated with the number of days older people spent time away from home but unrelated to time traveled by active means (walking and biking). No significant differences in active travel were found between the four study locations, despite differences in their respective built environments.The findings suggest that additional strategies to the creation of “age-friendly” environments are needed if older people are to increase their levels of outdoor physical activity. “Active aging” promotion campaigns may need to explicitly identify the benefits of walking outdoors to ambulatory older people as a means of maintaining their overall health, functional ability, and participation within society in the long-term and also encourage the development of community-based programs in order to facilitate regular walking for this group.

A 1H MRS study of probable Alzheimer's disease and normal aging: Implications for longitudinal monitoring of dementia progression

In order to evaluate the capability of 1H MRS to monitor longitudinal changes in subjects with probable Alzheimer's disease (AD), the temporal stability of the metabolite measures N-acetylaspartate and N- acetylaspartylglutamate (NA), total Creatine (Cr), myo-Inositol (mI), total Choline (Chol), NA/Cr, mI/Cr, Chol/Cr and NA/mI were investigated in a cohort of normal older adults. Only the metabolite measures NA, mI, Cr, NA/Cr, mI/Cr, and NA/mI were found to be stable after a mean interval of 260 days. Relative and absolute metabolite measures from a cohort of patients with probable AD were subsequently compared with data from a sample of normal older adult control subjects, and correlated with mental status and the degree of atrophy in the localized voxel. Concentrations of NA, NA/Cr, and NA/mI were significantly reduced in the AD group with concomitant significant increases in mI and mI/Cr. There were no differences between the two groups in measures of Cr, Chol, or Chol/Cr. Significant correlations between mental status as measured by the Mini-Mental State Examination and NA/mI, mI/Cr and NA were found. These metabolite measures were also significantly correlated with the extent of atrophy (as measured by CSF and GM composition) in the spectroscopy voxel.

MR image-based measurement of rates of change in volumes of brain structures. Part II: Application to a study of Alzheimer's disease and normal aging

We present global and regional rates of brain atrophy measured on serially acquired Tl-weighted brain MR images for a group of Alzheimer's disease (AD) patients and age-matched normal control (NC) subjects using the analysis procedure described in Part I. Three rates of brain atrophy: the rate of atrophy in the cerebrum, the rate of lateral ventricular enlargement and the rate of atrophy in the region of temporal lobes, were evaluated for 14 AD patients and 14 age-matched NC subjects. All three rates showed significant differences between the two groups. However, the greatest separation of the two groups was obtained when the regional rates were combined. This application has demonstrated that rates of brain atrophy, especially in specific regions of the brain, based on MR images can provide sensitive measures for evaluating the progression of AD. These measures will be useful for the evaluation of therapeutic effects of novel therapies for AD.

Effect of atmospheric aging on volatility and reactive oxygen species of biodiesel exhaust nano-particles

In the prospect of limited energy resources and climate change, effects of alternative biofuels on primary emissions are being extensively studied. Our two recent studies have shown that biodiesel fuel composition has a significant impact on primary particulate matter emissions. It was also shown that particulate matter caused by biodiesels was substantially different from the emissions due to petroleum diesel. Emissions appeared to have higher oxidative potential with the increase in oxygen content and decrease of carbon chain length and unsaturation levels of fuel molecules. Overall, both studies concluded that chemical composition of biodiesel is more important than its physical properties in controlling exhaust particle emissions. This suggests that the atmospheric aging processes, including secondary organic aerosol formation, of emissions from different fuels will be different as well. In this study, measurements were conducted on a modern common-rail diesel engine. To get more information on realistic properties of tested biodiesel particulate matter once they are released into the atmosphere, particulate matter was exposed to atmospheric oxidants, ozone and ultra-violet light; and the change in their properties was monitored for different biodiesel blends. Upon the exposure to oxidative agents, the chemical composition of the exhaust changes. It triggers the cascade of photochemical reactions resulting in the partitioning of semi-volatile compounds between the gas and particulate phase. In most of the cases, aging lead to the increase in volatility and oxidative potential, and the increment of change was mainly dependent on the chemical composition of fuels as the leading cause for the amount and the type of semi-volatile compounds present in the exhaust.

Aging and everyday technology

This paper presents a literature review and indicative findings that are part of ongoing research into aging and technology. The review finds that research on older technology users has contributed valuable information on the impact of age-related changes on technology use, as well as older adults’ acceptance and adoption of contemporary technologies. However, the majority of the research has been conducted from the perspective of age-related differences in use and performance, or it is medically-focused, examining the potential of technology to improve an individual’s quality of life (QoL), for example. Research on older people and technology does not adequately address the integration of technology into the everyday lives of older people. This paper identifies that there is substantial opportunity to examine older users’ everyday information and communication technology (ICT) use, and to inform technology design beyond measures of performance, usability and adoption.

UVB irradiation alters the activities and kinetic properties of the enzymes of energy metabolism in rat lens during aging

Ultraviolet (UV) radiation is one of the major risk factors of cataract (loss of eye-lens transparency). The influence of UVB radiation (300 nm, 100 mu W cm(-2)) on the activity and apparent kinetic constants (K-m and V-max) of rat lens hexokinase (HK;EC2.7.1.1), phosphofructokinase (PFK;EC2.7.1.11), isocitrate dehydrogenase (ICDH;EC1.1.1.41) and malate dehydrogenase (MDH;EC1.1.1.37) of energy metabolism has been investigated by irradiating the lens homogenate of three-and 12-month-old rats. In the three-month-old group specific activities of HK and PFK are reduced by 56 and 43 %, respectively, and there is no change in ICDH and MDH activities after a 24 h exposure. On the other hand, in the 12-month-old group the decreases are 72, 71, 24 and 16 % for HK, PFK. ICDH and MDH, respectively. UVB irradiation increases the apparent K-m of HK and PFK (in both age groups), whereas the K-m of ICDH and MDH is not altered. While the decrease in V-max of these enzymes due to UVB exposure is only marginal in three-month-old rats, it is more pronounced (significant) in 12-month-old rats. A similar decrease in enzyme activities of HK and PFK is also observe upon UVB exposure of the intact rat lens. The photoinduced changes in energy metabolism may in turn have a bearing on lens transparency, particularly at an older age.

Accelerated Multistress Aging of Outdoor Polymeric Insulators

Multistress aging of outdoor composite polymeric insulators continues to be a topic of interest for power transmission research community. Aging due to dry conditions alone at elevated temperatures and electric stress in the presence of UV radiation environment probably has not been explored. This paper deals with long-term accelerated multistress aging under the above conditions on full-scale 11 kV distribution class composite silicone rubber insulators. To evaluate the long-term synergistic effect of electric stress, temperature and UV radiation on insulators, they were subjected to accelerated aging in a specially designed multistress-aging chamber for 12000 hours. Chemical, physical and electrical changes due to degradation have been assessed using various techniques. It has been found that the content of low molecular weight molecules and hydrophobicity reduced significantly. Also, due to oxidation and aging there is appreciable increase in surface roughness and weight percentage of oxygen. Study is under progress and only intermediate results are presented in this paper.

Aging-in-place: Perspectives from the construction industry

Older adults report a desire to remain within the preferred environment for as long as possible. This desire is referred to as aging-in-place. Aging-in-place integrates housing and care options. Factors affecting the ability to remain within the preferred environment include current home designs, access to housing choices, social support networks, and community services, to name a few. Research supports physical and psychosocial benefits of aging-in-place for the individual. Home modifications have the potential to influence the quality of life in a number of positive directions that range from personal mobility to community engagement. Modifications range from minor to significant. Financial resources, contractor interest and expertise, consumer awareness and consumer opportunity affect the degree of change. Increasingly, construction professionals express an interest in learning more about aging-in place. Queries ranged from obtaining a greater understanding of the meaning of the concept, impact of demographic change on housing stock, and increased awareness of universal design features. This paper presents findings from a survey administered to current members of the Canadian Home Builders’ Association – Calgary Regional Office. Within this presentation, we report findings on members understanding of demographic change and the effect of this change on the current and future housing stock. We discuss perceived barriers and benefits of the development of business models to support aging-in-place. Finally, we conclude with discussion of educational support to enhance the understanding of aging-in-place.

Seed persistence in the field may be predicted by laboratory-controlled aging

Weed management is complicated by the presence of soil seed banks. The complexity of soil-seed interactions means that seed persistence in the field is often difficult to measure, let alone predict. Field trials, although accurate in their context, are time-consuming and expensive to conduct for individual species. Some ex situ techniques for estimating seed life expectancy have been proposed, but these fail to simulate the environmental complexity of the field. Also, it has been questioned whether techniques such as the controlled aging test (CAT) are useful indicators of field persistence. This study aimed to test the validity of the standard CAT (seed aging at 45 C and 60% relative humidity) in use at the Royal Botanic Gardens, Kew, U.K., for predicting field seed-persistence. Comparison of seed persistence and CAT data for 27 northwest European species suggested a significant positive correlation of 0.31. Subsequently, 13 species of emerging and common weeds of Queensland were assessed for their seed longevity using the CAT. The seed longevity data of these species in the CAT were linked with field seed-persistence data according to three broad seed-persistence categories: <1 yr, 1 to 3 yr, and >3 yr. We discuss the scope for using the CAT as a tool for rapid assignment of species to these categories. There is a need for further studies that compare predictions of seed persistence based on the CAT with seed persistence in the field for a larger range of species and environments.

Cellular Mechanisms of Sleep Homeostasis : Studies on Brain Energy Metabolism and Aging

Sleep is governed by a homeostatic process in which the duration and quality of previous wake regulate the subsequent sleep. Active wakefulness is characterized with high frequency cortical oscillations and depends on stimulating influence of the arousal systems, such as the cholinergic basal forebrain (BF), while cessation of the activity in the arousal systems is required for slow wave sleep (SWS) to occur. The site-specific accumulation of adenosine (a by-product of ATP breakdown) in the BF during prolonged waking /sleep deprivation (SD) is known to induce sleep, thus coupling energy demand to sleep promotion. The adenosine release in the BF is accompanied with increases in extracellular lactate and nitric oxide (NO) levels. This thesis was aimed at further understanding the cellular processes by which the BF is involved in sleep-wake regulation and how these processes are affected by aging. The BF function was studied simultaneously at three levels of organization: 1) locally at a cellular level by measuring energy metabolites 2) globally at a cortical level (the out-put area of the BF) by measuring EEG oscillations and 3) at a behavioral level by studying changes in vigilance states. Study I showed that wake-promoting BF activation, particularly with glutamate receptor agonist N-methyl-D-aspatate (NMDA), increased extracellular adenosine and lactate levels and led to a homeostatic increase in the subsequent sleep. Blocking NMDA activation during SD reduced the high frequency (HF) EEG theta (7-9 Hz) power and attenuated the subsequent sleep. In aging, activation of the BF during SD or experimentally with NMDA (studies III, IV), did not induce lactate or adenosine release and the increases in the HF EEG theta power during SD and SWS during the subsequent sleep were attenuated as compared to the young. These findings implicate that increased or continuous BF activity is important for active wake maintenance during SD as well as for the generation of homeostatic sleep pressure, and that in aging these mechanisms are impaired. Study II found that induction of the inducible NO synthase (iNOS) during SD is accompanied with activation of the AMP-activated protein kinase (AMPK) in the BF. Because decreased cellular energy charge is the most common cause for AMPK activation, this finding implicates that the BF is selectively sensitive to the metabolic demands of SD as increases were not found in the cortex. In aging (study III), iNOS expression and extracellular levels of NO and adenosine were not significantly increased during SD in the BF. Furthermore, infusion of NO donor into the BF did not lead to sleep promotion as it did in the young. These findings indicated that the NO (and adenosine) mediated sleep induction is impaired in aging and that it could at least partly be due to the reduced sensitivity of the BF to sleep-inducing factors. Taken together, these findings show that reduced sleep promotion by the BF contributes to the attenuated homeostatic sleep response in aging.

Raw data for project "Development of a DNA based aging technique for use in fisheries assessments" Fisheries and Development Corporation project 2007/033

The primary aim of this study was to determine the relationship between telomere length and age in a range of marine invertebrates including abalone (Haliotis spp) oysters (Saccostrea glomerata), spiny lobsters (Sagmariasus verreauxi formerly Jasus verreauxi and Jasus edwardsii) and school prawns (Metapenaeus macleayi). Additionally, this relationship was studied in a vertebrate organism using the freshwater fish Silver perch (Bidyanus bidyanus). Telomere length differences between tissues were also examined in some species such as Saccostrea glomerata, Sagmariasus verreauxi and Bidyanus bidyanus. In some cases cultured specimens of known age were used and this is quoted in the spreadsheets. For other wild-caught specimens where age was not known, size was used as a proxy for age. This may be a broad size class, or be determined by shell size or carapace length depending on the organism. Each spreadsheet contains raw data of telomere length estimates from Terminal Restriction Fragment Assays (TRF) for various individuals of each species including appropriate details such as age or size and tissue. Telomere length estimates are given in base pairs (bp). In most cases replicate experiments were conducted on groups of samples three times but on a small number of occasions only two replicate experiments were conducted. Further description of the samples can be found in final report of FRDC 2007/033. The arithmetic average for each individual (sample ID) across the two or three replicate experiments is also given. Bidyanus bidyanus (SilverPerch) Two sheets are contained within. a) Comparison of telomere length between different tissues (heart, liver and muscle) within the three year old age class - two replicate experiments were conducted. b) Comparison of telomere length between fish of different but known ages (0.25, 1, 2, and 3 years old) in each of three tissues, heart, liver and muscle – three replicate experiments were conducted per tissue. Haliotis spp (Abalone species) Three species were tested. H. asinina Telomere length was compared in two age classes-11 month and 18 month old abalone using muscle tissue from the foot. Within gel-variation was also estimated using a single sample run three times on one gel (replicate experiment). H. laevigata x H. rubra hybrids Telomere length was compared in three known age classes – two, three and four years old using muscle tissue from the foot. H. rubra Telomere length was compared in a range of different sized abalone using muscle tissue from the foot. Shell size is also given for each abalone Saccostrea glomerata Three sheets are contained within the file. a) Samples came from Moreton Bay Queensland in 2007. Telomere length was compared in two tissues (gill and mantle) of oysters in three age groups (1, 3 and 4 years) b) Samples came from Moreton Bay Queensland in 2009. Telomere length was compared in three age classes using DNA from gill tissue only c) Samples came from Wallis Lake, New South Wales. Telomere length was estimated from whole body minus the shell from 1 year old oysters, gill tissue of 3 age classes (1.5 years, 3 and 4 years), mantle tissue of two age classes (3 and 4 years). Sagmariasus verreauxi (formerly Jasus verreauxi) Telomere length was estimated from abdomen tissue of puerulus, gill and muscle tissue of 3 year old, large and very large size classes of lobsters. Jasus edwardsii Telomere length was measured in two size classes of lobsters- adults of varying sizes using muscle tissue and puerulus using tissues from the abdomen minus the exoskeleton. Metapenaeus macleayi Telomere length was measured in three size classes of school prawns adults. Muscle tissue was used, minus the exoskeleton.

Chemical changes during the aging and decomposition of composite solid propellants

During the thermal decomposition of orthorhombic ammonium perchlorate (AP) at 230°C, where the decomposition is only up to 30 wt %, there is an accumulation in the solid of acids, the concentration of which increases up to 15% decomposition, after which it decreases till it reaches the original value. Similar observations have been made in the polystyrene (PS)/AP propellant systems. Aging studies of PS/AP propellants have been carried out earlier [1], where it has been shown that for the aged propellants the thermal decomposition (TD) rate at 230°C and 260°C and ambient pressure burning rate (Image ) both increase and this increase is due to the formation of reactive intermediate “polystyrene peroxide (PSP).” In the present studies it has been observed that during the aging of the propellant at 150°C, the acid is formed and gets accumulated in the propellant, which may also be responsible for the increase in TD rate and perhaps may be more effective than PSP.