The regional electricity generation mix in Scotland: A portfolio selection approach

Standalone levelised cost assessments of electricity supply options miss an important contribution that renewable and non-fossil fuel technologies can make to the electricity portfolio: that of reducing the variability of electricity costs, and their potentially damaging impact upon economic activity. Portfolio theory applications to the electricity generation mix have shown that renewable technologies, their costs being largely uncorrelated with non-renewable technologies, can offer such benefits. We look at the existing Scottish generation mix and examine drivers of changes out to 2020. We assess recent scenarios for the Scottish generation mix in 2020 against mean-variance efficient portfolios of electricity-generating technologies. Each of the scenarios studied implies a portfolio cost of electricity that is between 22% and 38% higher than the portfolio cost of electricity in 2007. These scenarios prove to be “inefficient” in the sense that, for example, lower variance portfolios can be obtained without increasing portfolio costs, typically by expanding the share of renewables. As part of extensive sensitivity analysis, we find that Wave and Tidal technologies can contribute to lower risk electricity portfolios, while not increasing portfolio cost.Electricity generation mix, portfolio theory, regional energy policy

Antiretroviral Non-Adherence is Associated With a Retrieval Profile of Deficits in Verbal Episodic Memory.

HIV-associated deficits in verbal episodic memory are commonly associated with antiretroviral non-adherence; however, the specific aspects of memory functioning (e.g., encoding, consolidation, or retrieval) that underlie this established relationship are not well understood. This study evaluated verbal memory profiles of 202 HIV+ participants who underwent a 30-day electronic monitoring of antiretroviral adherence. At the group level, non-adherence was significantly associated with lower scores on immediate and delayed passage recall and word list learning. Retention and recognition of passages and word lists were not related to adherence. Participants were then classified as having either a normal verbal memory profile, a "subcortical" retrieval profile (i.e., impaired free recall with relatively spared recognition), or a "cortical" encoding profile (e.g., cued recall intrusions) based on the Massman et al. ( 1990 ) algorithm for the California Verbal Learning Test. HIV+ participants with a classic retrieval deficit had significantly greater odds of being non-adherent than participants with a normal or encoding profile. These findings suggest that adherence to prescribed antiretroviral regimens may be particularly vulnerable to disruption in HIV+ individuals due to deficits in the complex process of efficiently accessing verbal episodic information with minimal cues. A stronger relationship between non-adherence and passage (vs. word list) recall was also found and may reflect the importance of contextual features in remembering to take medications. Targeted interventions for enhancing and supporting episodic memory retrieval processes may improve antiretroviral adherence and overall health outcomes among persons living with HIV

Age-dependent molecular alterations in the autophagy pathway in HIVE patients and in a gp120 tg mouse model: reversal with beclin-1 gene transfer.

Aged (>50 years old) human immunodeficiency virus (HIV) patients are the fastest-growing segment of the HIV-infected population in the USA and despite antiretroviral therapy, HIV-associated neurocognitive disorder (HAND) prevalence has increased or remained the same among this group. Autophagy is an intracellular clearance pathway for aggregated proteins and aged organelles; dysregulation of autophagy is implicated in the pathogenesis of Parkinson's disease, Alzheimer's disease, and HAND. Here, we hypothesized that dysregulated autophagy may contribute to aging-related neuropathology in HIV-infected individuals. To explore this possibility, we surveyed autophagy marker levels in postmortem brain samples from a cohort of well-characterized <50 years old (young) and >50 years old (aged) HIV+ and HIV encephalitis (HIVE) patients. Detailed clinical and neuropathological data showed the young and aged HIVE patients had higher viral load, increased neuroinflammation and elevated neurodegeneration; however, aged HIVE postmortem brain tissues showed the most severe neurodegenerative pathology. Interestingly, young HIVE patients displayed an increase in beclin-1, cathepsin-D and light chain (LC)3, but these autophagy markers were reduced in aged HIVE cases compared to age-matched HIV+ donors. Similar alterations in autophagy markers were observed in aged gp120 transgenic (tg) mice; beclin-1 and LC3 were decreased in aged gp120 tg mice while mTor levels were increased. Lentivirus-mediated beclin-1 gene transfer, that is known to activate autophagy pathways, increased beclin-1, LC3, and microtubule-associated protein 2 expression while reducing glial fibrillary acidic protein and Iba1 expression in aged gp120 tg mice. These data indicate differential alterations in the autophagy pathway in young versus aged HIVE patients and that autophagy reactivation may ameliorate the neurodegenerative phenotype in these patients

Neurocognitive impairment is associated with lower health literacy among persons living with HIV infection.

This study sought to determine the effects of HIV-associated neurocognitive disorders (HAND) on health literacy, which encompasses the ability to access, understand, appraise, and apply health-related information. Participants included 56 HIV seropositive individuals, 24 of whom met Frascati criteria for HAND, and 24 seronegative subjects who were comparable on age, education, ethnicity, and oral word reading. Each participant was administered a brief battery of well-validated measures of health literacy, including the Expanded Numeracy Scale (ENS), Newest Vital Sign (NVS), Rapid Estimate of Adult Literacy in Medicine (REALM), and Brief Health Literacy Screen (BHLS). Results revealed significant omnibus differences on the ENS and NVS, which were driven by poorer performance in the HAND group. There were no significant differences on the REALM or the BHLS by HAND status. Among individuals with HAND, lower scores on the NVS were associated with greater severity of neurocognitive dysfunction (e.g., working memory and verbal fluency) and self-reported dependence in activities of daily living. These preliminary findings suggest that HAND hinders both fundamental (i.e., basic knowledge, such as numeracy) and critical (i.e., comprehension and application of healthcare information) health literacy capacities, and therefore may be an important factor in the prevalence of health illiteracy. Health literacy-focused intervention may play an important role in the treatment and health trajectories among persons living with HIV infection

Fibroblast growth factors 1 and 2 in cerebrospinal fluid are associated with HIV disease, methamphetamine use, and neurocognitive functioning.

BackgroundHuman immunodeficiency virus (HIV) and methamphetamine use commonly affect neurocognitive (NC) functioning. We evaluated the relationships between NC functioning and two fibroblast growth factors (FGFs) in volunteers who differed in HIV serostatus and methamphetamine dependence (MAD).MethodsA total of 100 volunteers were categorized into four groups based on HIV serostatus and MAD in the prior year. FGF-1 and FGF-2 were measured in cerebrospinal fluid by enzyme-linked immunosorbent assays along with two reference biomarkers (monocyte chemotactic protein [MCP]-1 and neopterin). Comprehensive NC testing was summarized by global and domain impairment ratings.ResultsSixty-three volunteers were HIV+ and 59 had a history of MAD. FGF-1, FGF-2, and both reference biomarkers differed by HIV and MAD status. For example, FGF-1 levels were lower in subjects who had either HIV or MAD than in HIV- and MAD- controls (P=0.003). Multivariable regression identified that global NC impairment was associated with an interaction between FGF-1 and FGF-2 (model R(2)=0.09, P=0.01): higher FGF-2 levels were only associated with neurocognitive impairment among subjects who had lower FGF-1 levels. Including other covariates in the model (including antidepressant use) strengthened the model (model R(2)=0.18, P=0.004) but did not weaken the association with FGF-1 and FGF-2. Lower FGF-1 levels were associated with impairment in five of seven cognitive domains, more than FGF-2, MCP-1, or neopterin.ConclusionThese findings provide in vivo support that HIV and MAD alter expression of FGFs, which may contribute to the NC abnormalities associated with these conditions. These cross-sectional findings cannot establish causality and the therapeutic benefits of recombinant FGF-1 need to be investigated

Test-Retest Reliability of Standard Deviation of Lane Position as Assessed on a PC-Based Driving Simulator

Driving is an everyday activity that is commonly affected by neurologic disorders and medical treatments. A frequently used metric for assessing driving ability is the standard deviation of lane position (SDLP), or the amount that subjects “swerve” within their driving lane. This measurement has been used with individuals under the influence of alcohol, illicit drugs, and prescribed medications in both on-road and simulator studies. Although good test-retest reliability is critical if one is to measure change in individuals over time, there is surprisingly limited data regarding the test-retest reliability of SDLP. Objective. To examine the test-retest reliability of SDLP in subjects tested at (1) a 3-month retest interval (a time frame common to clinical trials), and (2) a year or longer retest interval (a time period over which one might track changes in neurologic patients. Methods. Group 1 completed retesting an average of 84 (s.d. = 8.1) days after their initial simulator assessment. Both HIV negative (HIV-; n = 16) and positive (HIV+; n = 13) subjects were included to explore short-term reliability in control and mildly ill patient groups. All HIV+ subjects were medically asymptomatic, and unlikely to experience HIV-related changes over this interval. Two HIV+ subjects were neuropsychologically (NP) impaired. Group 2 (n = 31), a different cohort, was retested an average of 19.8 (8.3) months after baseline. All subjects completed NP evaluations at baseline and follow-up, with NP status rated on a scale of 1 (above average) to 9 (severe impairment) by a clinician blinded to simulator performance. Twelve subjects (39%) were NP impaired. In order to examine reliability in a stable neurologic cohort, all subjects were selected because they remained at the same level of NP functioning at follow-up. SDLP was assessed in both groups using an interactive PC-based driving simulator that consisted of a monitor, steering wheel, and brake/accelerator pedals. Participants were required to maintain lane position while holding a constant speed (55 mph) and responding to divided attention tasks in the corner of the monitor. Group 2 completed an existing, standardized scenario (TOPS), while Group 1 completed a newly developed driving scenario. Both simulations lasted approximately 7 minutes. Results. Combined reliability for Group 1 was .74. Test-retest reliability was .68 for the HIVand .83 for the HIV+ subjects. For Group 2, SDLP was significantly correlated with NP functioning at baseline (r = .5, p = .005) and follow-up (r = .48, p = .006), with impaired subjects evidencing a higher SDLP than NP normal subjects at both baseline (mean of 1.9 vs 1.2; p = .006) and follow-up (1.7 vs 1.1, p = .01). Combined test-retest reliability for Group 2 was .86. The NP normal group had a test-retest reliability of .74; test-retest reliability for the NP impaired group was .87. Conclusions. SDLP is a reliable measure for periods ranging from months to years when assessed in cognitively stable subjects. As such, this may serve as a useful tool in tracking the effects of neurologic disorders and pharmacologic treatments on driving abilities

Photodetector Focal Plane Arrays Integrated with Silicon Micropyramidal Structures in MWIR

Light-concentrating truncated Si micropyramidal arrays with 54.7 degree sidewall angles were successfully integrated with PtSi Schottky barrier photodetectors. Four different devices consisting of 10 x 10 photodetectors with 60 um pitch combined in parallel were tested, where significant enhancement capability was demonstrated by the Si micropyramids. The device consisting of one hundred 22 um square detectors monolithically integrated with the light-concentrating micropyramidal array displayed signal enhancement of up to 4 times compared to the same size 22 um square photodetector device without the light concentrators.Comment: 4 pages, 2 figures, GOMACTech 202

The Regional Electricity Generation Mix in Scotland : a Portfolio Selection Approach

Standalone levelised cost assessments of electricity supply options miss an important contribution that renewable and non-fossil fuel technologies can make to the electricity portfolio: that of reducing the variability of electricity costs, and their potentially damaging impact upon economic activity. Portfolio theory applications to the electricity generation mix have shown that renewable technologies, their costs being largely uncorrelated with non-renewable technologies, can offer such benefits. We look at the existing Scottish generation mix and examine drivers of changes out to 2020. We assess recent scenarios for the Scottish generation mix in 2020 against mean-variance efficient portfolios of electricity-generating technologies. Each of the scenarios studied implies a portfolio cost of electricity that is between 22% and 38% higher than the portfolio cost of electricity in 2007. These scenarios prove to be “inefficient” in the sense that, for example, lower variance portfolios can be obtained without increasing portfolio costs, typically by expanding the share of renewables. As part of extensive sensitivity analysis, we find that Wave and Tidal technologies can contribute to lower risk electricity portfolios, while not increasing portfolio cost

Effects of traumatic brain injury on cognitive functioning and cerebral metabolites in HIV-infected individuals.

We explored the possible augmenting effect of traumatic brain injury (TBI) history on HIV (human immunodeficiency virus) associated neurocognitive complications. HIV-infected participants with self-reported history of definite TBI were compared to HIV patients without TBI history. Groups were equated for relevant demographic and HIV-associated characteristics. The TBI group evidenced significantly greater deficits in executive functioning and working memory. N-acetylaspartate, a putative marker of neuronal integrity, was significantly lower in the frontal gray matter and basal ganglia brain regions of the TBI group. Together, these results suggest an additional brain impact of TBI over that from HIV alone. One clinical implication is that HIV patients with TBI history may need to be monitored more closely for increased risk of HIV-associated neurocognitive disorder signs or symptoms