FlashBack: Immersive Virtual Reality on Weak Mobile Devices via Rendering Memoization

Virtual Reality Head-mounted Displays (HMDs) are attracting users with the promise of full sensory immersion in virtual environments. Creating the illusion of immersion for a near-eye display results in very heavy rendering workloads: low latency, high framerate, and high visual quality are all needed. Tethered VR setups in which the HMD is bound to a powerful gaming desktop limit mobility and exploration, and are difficult to deploy widely. Products such as Google Cardboard and Samsung Gear VR purport to offer any user a mobile VR experience, but their GPUs are power-constrained and therefore fail to produce acceptable frame rate and latency for even scenes of modest visual quality. We present FlashBack, an unorthodox design point for HMD VR that eschews all real-time scene rendering. Instead, FlashBack aggressively precomputes and caches all possible images that a VR user might encounter. FlashBack memoizes costly rendering effort in an offline step to build a cache full of panoramic images. During runtime, FlashBack constructs and maintains a hierarchical storage cache index to quickly lookup images that the user should be seeing. On a cache miss, FlashBack uses fast approximations of the correct image while concurrently fetching better cache entries for future requests. Moreover, FlashBack not only works for static scenes, but also for dynamic scenes with moving and animated objects. We evaluate a prototype implementation of FlashBack and report up to an 8x improvement in framerate, 97x reduction in energy consumption per frame, and 15x latency reduction compared to a locally-rendered mobile VR setup. In some cases, FlashBack even delivers better framerates and responsiveness than a tethered HMD configuration on graphically complex scenes

Where Would You Turn for Help? Older Adults’ Awareness of Community Support Services

Previous findings on older adults’ awareness of community support services (CSSs) have been inconsistent and marred by acquiescence or over-claiming bias. To address this issue, this study used a series of 12 vignettes to describe common situations faced by older adults for which CSSs might be appropriate. In telephone interviews, 1,152 adults aged 50 years and over were read a series of vignettes and asked if they were able to identify a community organization or agency that they may turn to in that situation. They were also asked about their most important sources of information about CSSs. The findings show that, using a vignette methodology, awareness of CSSs is much lower than previously thought. The most important sources of information about CSSs included information and referral sources, the telephone book, doctors’ offices, and word of mouth.aging, community support services, awareness, knowledge, acquiescence bias, vignette methodology

Where Would You Turn for Help? Older Adults’ Awareness of Community Health and Support Services for Dementia Care

Previous findings on older adults’ awareness of community support services (CSSs) have been inconsistent and marred by acquiescence or over-claiming bias. To address this issue, this study used a series of 12 vignettes to describe common situations faced by older adults for which CSSs might be appropriate. In telephone interviews, 1,152 adults aged 50 years and over were read a series of vignettes and asked if they were able to identify a community organization or agency that they may turn to in that situation. They were also asked about their most important sources of information about CSSs. The findings show that, using a vignette methodology, awareness of CSSs is much lower than previously thought. The most important sources of information about CSSs included information and referral sources, the telephone book, doctors’ offices, and word of mouth.aging, community support services, awareness, knowledge, acquiescence bias, vignette methodology

Eliminating State Entanglement with Checkpoint-based Virtualization of Mobile OS Services

Abstract Mobile operating systems have adopted a service model in which applications access system functionality by interacting with various OS Services in separate processes. These interactions cause application-specific states to be spread across many service processes, a problem we identify as state entanglement. State entanglement presents significant challenges to a wide variety of computing goals: fault isolation, fault tolerance, application migration, live update, and application speculation. We propose CORSA, a novel virtualization solution that uses a lightweight checkpoint/restore mechanism to virtualize OS Services on a per-application basis. This cleanly encapsulates a single application's service-side states into a private virtual service instance, eliminating state entanglement and enabling the above goals. We present empirical evidence that our ongoing implementation of CORSA on Android is feasible with low overhead, even in the worst case of high frequency service interactions

CHANGES IN BALANCE AND JOINT POSITION SENSE DURING A 12-DAY HIGH ALTITUDE TREK

The purpose of this study was to investigate changes in postural control and knee joint position sense (KJPS) during a trek to high altitude. Postural control during standing balance and KJPS were measured in 12 participants at sea-level, 3619m, 4600m and 5140m. Total (p = 0.003, d=1.9) and anterior-posterior sway velocity (p= 0.001, d=1.9) during standing balance with eyes open velocity was significantly greater at altitudes of 3619m and 5140m when compared with sea level. Despite a gradual ascent profile, exposure to 3619 m was associated with impairments in postural control. Importantly, these impairments did not worsen at higher altitudes. The present findings should be considered during future trekking expeditions when considering specific strategies to manage impairments in postural control that occur with increasing altitude

Multiple mitochondrial thioesterases have distinct tissue and substrate specificity and CoA regulation, suggesting unique functional roles.

Acyl-CoA thioesterases (Acots) hydrolyze fatty acyl-CoA esters. Acots in the mitochondrial matrix are poised to mitigate β-oxidation overload and maintain CoA availability. Several Acots associate with mitochondria, but whether they all localize to the matrix, are redundant, or have different roles is unresolved. Here, we compared the suborganellar localization, activity, expression, and regulation among mitochondrial Acots (Acot2, -7, -9, and -13) in mitochondria from multiple mouse tissues and from a model of Acot2 depletion. Acot7, -9, and -13 localized to the matrix, joining Acot2 that was previously shown to localize there. Mitochondria from heart, skeletal muscle, brown adipose tissue, and kidney robustly expressed Acot2, -9, and -13; Acot9 levels were substantially higher in brown adipose tissue and kidney mitochondria, as was activity for C4:0-CoA, a unique Acot9 substrate. In all tissues, Acot2 accounted for about half of the thioesterase activity for C14:0-CoA and C16:0-CoA. In contrast, liver mitochondria from fed and fasted mice expressed little Acot activity, which was confined to long-chain CoAs and due mainly to Acot7 and Acot13 activities. Matrix Acots occupied different functional niches, based on substrate specificity (Acot9 versus Acot2 and -13) and strong CoA inhibition (Acot7, -9, and -13, but not Acot2). Interpreted in the context of β-oxidation, CoA inhibition would prevent Acot-mediated suppression of β-oxidation, while providing a release valve when CoA is limiting. In contrast, CoA-insensitive Acot2 could provide a constitutive siphon for long-chain fatty acyl-CoAs. These results reveal how the family of matrix Acots can mitigate β-oxidation overload and prevent CoA limitation. © 2019 American Society for Biochemistry and Molecular Biology Inc.. All rights reserved

Natural Glycoforms of Human Interleukin 6 show atypical plasma clearance

A library of glycoforms of human interleukin 6 (IL‐6) comprising complex and mannosidic N‐glycans was generated by semisynthesis. The three segments were connected by sequential native chemical ligation followed by two‐step refolding. The central glycopeptide segments were assembled by pseudoproline‐assisted Lansbury aspartylation and subsequent enzymatic elongation of complex N‐glycans. Nine IL‐6 glycoforms were synthesized, seven of which were evaluated for in vivo plasma clearance in rats and compared to non‐glycosylated recombinant IL‐6 from E. coli. Each IL‐6 glycoform was tested in three animals and reproducibly showed individual serum clearances depending on the structure of the N‐glycan. The clearance rates were atypical, since the 2,6‐sialylated glycoforms of IL‐6 cleared faster than the corresponding asialo IL‐6 with terminal galactoses. Compared to non‐glycosylated IL‐6 the plasma clearance of IL‐6 glycoforms was delayed in the presence of larger and multibranched N‐glycans in most case

Measurements of the Production, Decay and Properties of the Top Quark: A Review

With the full Tevatron Run II and early LHC data samples, the opportunity for furthering our understanding of the properties of the top quark has never been more promising. Although the current knowledge of the top quark comes largely from Tevatron measurements, the experiments at the LHC are poised to probe top-quark production and decay in unprecedented regimes. Although no current top quark measurements conclusively contradict predictions from the standard model, the precision of most measurements remains statistically limited. Additionally, some measurements, most notably the forward-backward asymmetry in top quark pair production, show tantalizing hints of beyond-the-Standard-Model dynamics. The top quark sample is growing rapidly at the LHC, with initial results now public. This review examines the current status of top quark measurements in the particular light of searching for evidence of new physics, either through direct searches for beyond the standard model phenomena or indirectly via precise measurements of standard model top quark properties

Changes in balance and joint position sense during a 12-day high altitude trek: The British Services Dhaulagiri medical research expedition

<div><p>Postural control and joint position sense are essential for safely undertaking leisure and professional activities, particularly at high altitude. We tested whether exposure to a 12-day trek with a gradual ascent to high altitude impairs postural control and joint position sense. This was a repeated measures observational study of 12 military service personnel (28±4 years). Postural control (sway velocity measured by a portable force platform) during standing balance, a Sharpened Romberg Test and knee joint position sense were measured, in England (113m elevation) and at 3 research camps (3619m, 4600m and 5140m) on a 12-day high altitude trek in the Dhaulagiri region of Nepal. Pulse oximetry, and Lake Louise scores were also recorded on the morning and evening of each trek day. Data were compared between altitudes and relationships between pulse oximetry, Lake Louise score, and sway velocity were explored. Total sway velocity during standing balance with eyes open (p = 0.003, d = 1.9) and during Sharpened Romberg test with eyes open (p = 0.007, d = 1.6) was significantly greater at altitudes of 3619m and 5140m when compared with sea level. Anterior-posterior sway velocity during standing balance with eyes open was also significantly greater at altitudes of 3619m and 5140m when compared with sea level (p = 0.001, d = 1.9). Knee joint position sense was not altered at higher altitudes. There were no significant correlations between Lake Louise scores, pulse oximetry and postural sway. Despite a gradual ascent profile, exposure to 3619 m was associated with impairments in postural control without impairment in knee joint position sense. Importantly, these impairments did not worsen at higher altitudes of 4600 m or 5140 m. The present findings should be considered during future trekking expeditions when developing training strategies targeted to manage impairments in postural control that occur with increasing altitude.</p></div

Changes in appetite, energy intake, body composition and circulating ghrelin constituents during an incremental trekking ascent to high altitude

Purpose Circulating acylated ghrelin concentrations are associated with altitude-induced anorexia in laboratory environments, but have never been measured at terrestrial altitude. This study examined time course changes in appetite, energy intake, body composition, and ghrelin constituents during a high-altitude trek. Methods Twelve participants [age: 28(4) years, BMI 23.0(2.1) kg m−2] completed a 14-day trek in the Himalayas. Energy intake, appetite perceptions, body composition, and circulating acylated, des-acylated, and total ghrelin concentrations were assessed at baseline (113 m, 12 days prior to departure) and at three fixed research camps during the trek (3619 m, day 7; 4600 m, day 10; 5140 m, day 12). Results Relative to baseline, energy intake was lower at 3619 m (P = 0.038) and 5140 m (P = 0.016) and tended to be lower at 4600 m (P = 0.056). Appetite perceptions were lower at 5140 m (P = 0.027) compared with baseline. Acylated ghrelin concentrations were lower at 3619 m (P = 0.046) and 4600 m (P = 0.038), and tended to be lower at 5140 m (P = 0.070), compared with baseline. Des-acylated ghrelin concentrations did not significantly change during the trek (P = 0.177). Total ghrelin concentrations decreased from baseline to 4600 m (P = 0.045). Skinfold thickness was lower at all points during the trek compared with baseline (P ≤ 0.001) and calf girth decreased incrementally during the trek (P = 0.010). Conclusions Changes in plasma acylated and total ghrelin concentrations may contribute to the suppression of appetite and energy intake at altitude, but differences in the time course of these responses suggest that additional factors are also involved. Interventions are required to maintain appetite and energy balance during trekking at terrestrial altitudes