Testing alternative fuels, solar-thermal systems

The Terrestrial Energy Systems Technical Committee works to advance the application of engineering sciences and systems engineering to the production, storage, distribution and conservation of energy for terrestrial uses

Job characteristics and mental health for older workers

Background: Adverse job characteristics have been linked with increased incidence of depression and anxiety in working populations. However, the association between job characteristics and mental health, in an older working population while controlling for personality traits, is less well known. Aims: To examine the association between job characteristics (job demands and job control) and mental health (depression and anxiety) for older workers while controlling for personality traits. Methods: A sample of workers aged 50-69 years were recruited from a primary health care clinic in Southern Ireland. Job characteristics were measured using the Copenhagen Psychosocial Questionnaire; demands (quantitative and cognitive) and control (influence at work and possibilities for development). Personality traits were measured using the Ten-Item Personality Inventory, depression was measured using the Center for Epidemiological Studies-Depression Scale and anxiety was measured using the Hospital Anxiety and Depression Scale. Descriptive analysis, simple and multiple linear regression analyses were conducted. Results: The final sample size was 1025 with an initial 67% response rate. Multiple linear regression analysis showed job characteristics (in particular, job demands) to be significant positive predictors of symptoms of depression and anxiety. The inverse was true for job control variables and symptoms of depression. Neither possibilities for development nor influence at work were associated with symptoms of anxiety. Conclusions: Our findings indicate that despite potential confounders, higher demands at work can impact the worker's mental health negatively. Reducing job demands and encouraging role development may benefit the mental health of older workers

The effect of alternative fuels on gaseous and particulate matter (PM) emission performance in an auxiliary power unit (APU)

There is a growing interest in the use of alternative fuels in gas turbine engines to reduce emissions. Testing of alternative fuels is expensive when done on a large-scale gas turbine engine. In this study, a re-commissioned small gas turbine auxiliary power unit (APU) has been used to test various blends of Jet A-1, synthetic paraffinic kerosene (SPK) and diesel with as well as eight other novel fuels. A detailed analysis of performance, gaseous emissions and particulate emissions has been presented in this study. It is observed that aromatic content in general as well as the particular chemical composition of the aromatic compound plays a vital role in particulate emissions generation. SPK fuel shows substantially lower particulate emissions with respect to Jet A. However, not all the species of aromatics negatively impact particulate emissions. Gaseous emissions measured are comparable for all the fuels tested in this study

Seeing ‘Where’ through the Ears: Effects of Learning-by-Doing and Long-Term Sensory Deprivation on Localization Based on Image-to-Sound Substitution

BACKGROUND: Sensory substitution devices for the blind translate inaccessible visual information into a format that intact sensory pathways can process. We here tested image-to-sound conversion-based localization of visual stimuli (LEDs and objects) in 13 blindfolded participants. METHODS AND FINDINGS: Subjects were assigned to different roles as a function of two variables: visual deprivation (blindfolded continuously (Bc) for 24 hours per day for 21 days; blindfolded for the tests only (Bt)) and system use (system not used (Sn); system used for tests only (St); system used continuously for 21 days (Sc)). The effect of learning-by-doing was assessed by comparing the performance of eight subjects (BtSt) who only used the mobile substitution device for the tests, to that of three subjects who, in addition, practiced with it for four hours daily in their normal life (BtSc and BcSc); two subjects who did not use the device at all (BtSn and BcSn) allowed assessment of its use in the tasks we employed. The impact of long-term sensory deprivation was investigated by blindfolding three of those participants throughout the three week-long experiment (BcSn, BcSn/c, and BcSc); the other ten subjects were only blindfolded during the tests (BtSn, BtSc, and the eight BtSt subjects). Expectedly, the two subjects who never used the substitution device, while fast in finding the targets, had chance accuracy, whereas subjects who used the device were markedly slower, but showed much better accuracy which improved significantly across our four testing sessions. The three subjects who freely used the device daily as well as during tests were faster and more accurate than those who used it during tests only; however, long-term blindfolding did not notably influence performance. CONCLUSIONS: Together, the results demonstrate that the device allowed blindfolded subjects to increasingly know where something was by listening, and indicate that practice in naturalistic conditions effectively improved "visual" localization performance

Online versus paper-based screening for depression and anxiety in adults with cystic fibrosis in Ireland: a cross-sectional exploratory study

Objective: To compare online and paper-based screening for depression and anxiety in adults with cystic fibrosis (CF). Design and setting: Cross-sectional study in CF clinics in Ireland and through the Cystic Fibrosis Ireland online community. Participants: 160 adult patients aged 18 or above were recruited. Of these, 147 were included in the analysis; 83 online and 64 paper-based. The remaining 13 were excluded because of incomplete data. Measures: Depression and anxiety were measured using the Hospital Anxiety and Depression Scale (HADS). Data on pulmonary function (forced expiratory volume in 1 s %) and body mass index were self-reported based on clinical assessments. Sociodemographic data were collected. Results: Compared with the paper-based participants, the online participants were more likely to be female (61.7% vs 48.4%), older (mean 32.2 vs 28.2 years) and were more likely to be married (32.5% vs 15.6%), living with their spouse or partner (42.5% vs 22.6%) and working either full time (33.7% vs 15.9%) or part time (30.1%vs 17.5%). The prevalence rates of elevated anxiety and depression were not significantly different (P=0.71 and P=0.56). HADS anxiety and depression scores were not statistically different between online (P=0.83) and paper-based (P=0.92) participants based on Mann-Whitney U test. A significant negative correlation was found between depression and pulmonary function (r=−0.39, P=0.01) and anxiety and pulmonary function (r=−0.36, P=0.02). Based on Cronbach’s alpha, there were no statistically significant differences between the online and paper-based participants on the internal consistency of the HADS anxiety (P=0.073) and depression (P=0.378) scales. Conclusions: Our findings suggest that online and paper-based screening for depression and anxiety in adult patients with CF yield comparable findings on prevalence rates and scores, associations with health and internal consistency of subscales. This study highlights that online screening offers an alternative method to paper-based screening. Further research with a larger sample and assessment of measurement equivalence between online and paper based screening is needed to confirm our results

Cytoskeletal Signaling: Is Memory Encoded in Microtubule Lattices by CaMKII Phosphorylation?

Memory is attributed to strengthened synaptic connections among particular brain neurons, yet synaptic membrane components are transient, whereas memories can endure. This suggests synaptic information is encoded and ‘hard-wired’ elsewhere, e.g. at molecular levels within the post-synaptic neuron. In long-term potentiation (LTP), a cellular and molecular model for memory, post-synaptic calcium ion (Ca2+) flux activates the hexagonal Ca2+-calmodulin dependent kinase II (CaMKII), a dodacameric holoenzyme containing 2 hexagonal sets of 6 kinase domains. Each kinase domain can either phosphorylate substrate proteins, or not (i.e. encoding one bit). Thus each set of extended CaMKII kinases can potentially encode synaptic Ca2+ information via phosphorylation as ordered arrays of binary ‘bits’. Candidate sites for CaMKII phosphorylation-encoded molecular memory include microtubules (MTs), cylindrical organelles whose surfaces represent a regular lattice with a pattern of hexagonal polymers of the protein tubulin. Using molecular mechanics modeling and electrostatic profiling, we find that spatial dimensions and geometry of the extended CaMKII kinase domains precisely match those of MT hexagonal lattices. This suggests sets of six CaMKII kinase domains phosphorylate hexagonal MT lattice neighborhoods collectively, e.g. conveying synaptic information as ordered arrays of six “bits”, and thus “bytes”, with 64 to 5,281 possible bit states per CaMKII-MT byte. Signaling and encoding in MTs and other cytoskeletal structures offer rapid, robust solid-state information processing which may reflect a general code for MT-based memory and information processing within neurons and other eukaryotic cells

Heritable Differences in Schooling Behavior among Threespine Stickleback Populations Revealed by a Novel Assay

Identifying the proximate and ultimate mechanisms of social behavior remains a major goal of behavioral biology. In particular, the complex social interactions mediating schooling behavior have long fascinated biologists, leading to theoretical and empirical investigations that have focused on schooling as a group-level phenomenon. However, methods to examine the behavior of individual fish within a school are needed in order to investigate the mechanisms that underlie both the performance and the evolution of schooling behavior. We have developed a technique to quantify the schooling behavior of an individual in standardized but easily manipulated social circumstances. Using our model school assay, we show that threespine sticklebacks (Gasterosteus aculeatus) from alternative habitats differ in behavior when tested in identical social circumstances. Not only do marine sticklebacks show increased association with the model school relative to freshwater benthic sticklebacks, they also display a greater degree of parallel swimming with the models. Taken together, these data indicate that marine sticklebacks exhibit a stronger tendency to school than benthic sticklebacks. We demonstrate that these population-level differences in schooling tendency are heritable and are shared by individuals within a population even when they have experienced mixed-population housing conditions. Finally, we begin to explore the stimuli that elicit schooling behavior in these populations. Our data suggest that the difference in schooling tendency between marine and benthic sticklebacks is accompanied by differential preferences for social vs. non-social and moving vs. stationary shelter options. Our study thus provides novel insights into the evolution of schooling behavior, as well as a new experimental approach to investigate the genetic and neural mechanisms that underlie this complex social behavior

The Zinc Dyshomeostasis Hypothesis of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia in the elderly. Hallmark AD neuropathology includes extracellular amyloid plaques composed largely of the amyloid-β protein (Aβ), intracellular neurofibrillary tangles (NFTs) composed of hyper-phosphorylated microtubule-associated protein tau (MAP-tau), and microtubule destabilization. Early-onset autosomal dominant AD genes are associated with excessive Aβ accumulation, however cognitive impairment best correlates with NFTs and disrupted microtubules. The mechanisms linking Aβ and NFT pathologies in AD are unknown. Here, we propose that sequestration of zinc by Aβ-amyloid deposits (Aβ oligomers and plaques) not only drives Aβ aggregation, but also disrupts zinc homeostasis in zinc-enriched brain regions important for memory and vulnerable to AD pathology, resulting in intra-neuronal zinc levels, which are either too low, or excessively high. To evaluate this hypothesis, we 1) used molecular modeling of zinc binding to the microtubule component protein tubulin, identifying specific, high-affinity zinc binding sites that influence side-to-side tubulin interaction, the sensitive link in microtubule polymerization and stability. We also 2) performed kinetic modeling showing zinc distribution in extra-neuronal Aβ deposits can reduce intra-neuronal zinc binding to microtubules, destabilizing microtubules. Finally, we 3) used metallomic imaging mass spectrometry (MIMS) to show anatomically-localized and age-dependent zinc dyshomeostasis in specific brain regions of Tg2576 transgenic, mice, a model for AD. We found excess zinc in brain regions associated with memory processing and NFT pathology. Overall, we present a theoretical framework and support for a new theory of AD linking extra-neuronal Aβ amyloid to intra-neuronal NFTs and cognitive dysfunction. The connection, we propose, is based on β-amyloid-induced alterations in zinc ion concentration inside neurons affecting stability of polymerized microtubules, their binding to MAP-tau, and molecular dynamics involved in cognition. Further, our theory supports novel AD therapeutic strategies targeting intra-neuronal zinc homeostasis and microtubule dynamics to prevent neurodegeneration and cognitive decline