Three-Body Capture of Irregular Satellites: Application to Jupiter

We investigate a new theory of the origin of the irregular satellites of the giant planets: capture of one member of a ~100-km binary asteroid after tidal disruption. The energy loss from disruption is sufficient for capture, but it cannot deliver the bodies directly to the observed orbits of the irregular satellites. Instead, the long-lived capture orbits subsequently evolve inward due to interactions with a tenuous circumplanetary gas disk. We focus on the capture by Jupiter, which, due to its large mass, provides the most stringent test of our model. We investigate the possible fates of disrupted bodies, the differences between prograde and retrograde captures, and the effects of Callisto on captured objects. We make an impulse approximation and discuss how it allows us to generalize capture results from equal-mass binaries to binaries with arbitrary mass ratios. We find that at Jupiter, binaries offer an increase of a factor of ~10 in the capture rate of 100-km objects as compared to single bodies, for objects separated by tens of radii that approach the planet on relatively low-energy trajectories. These bodies are at risk of collision with Callisto, but may be preserved by gas drag if their pericenters are raised quickly enough. We conclude that our mechanism is as capable of producing large irregular satellites as previous suggestions, and it avoids several problems faced by alternative models.Comment: 39 pages, 12 figures, 1 table, submitted to Icaru

Impact of residential energy system sizing and control over heat pump’s system cost and reliability

Using a simulation-based approach, this work analyses the impact that different energy unit sizes and control methodologies will have over the capital and running costs of an air source heat pump (ASHP) system to be installed in a refurbished dwelling. A total of 9 different heating configuration options were investigated and the cumulative cash flow over a period of 10 years (including initial investment) was utilized to compare the systems from a customer perspective. Additionally, in selected cases, the cycling of the heat pump was calculated in order to estimate the life-span of the device. The building and heat pump systems were simulated using TRNSYS energy system models. The results revealed the sensitivity of the system’s costs and life-span to its operating characteristics. For example, operating the system as a direct gas boiler replacement resulted in capital costs above £10,000 and the unit's life span reduced by half in comparison to more favourable operational strategies. The results highlight the fact that the successful technical and financial performance of heat pumps within the UK’s residential market will depend of designers, installers and end-users’ awareness regarding optimal operational strategies for this technology

Stem Cell Research and Same Sex Reproduction

Recent advances in stem cell research suggest that in the future it may be possible to create eggs and sperm from human stem cells through a process that we term in vitro gametogenesis (IVG). IVG would allow treatment of some currently untreatable forms of infertility. It may also allow same-sex couples to have genetically-related children. For example, cells taken from one man could potentially be used to create an egg, which could then be fertilised using naturally produced sperm from another man to create a genetically-related child with half of its DNA from each of the men. In this chapter, we consider whether this technology could justifiably be denied to same-sex couples if it were made available as a fertility treatment to different-sex couples. We argue that it could not

In-situ holographic elastic moduli measurements from boreholes

We have developed a unique technique employing optical holography to measure the static Young's modulus (E) from a borehole. In the experiment, a known point force induces micron scale displacements on the borehole wall which are recorded by a double-exposure hologram. Raw data consist of dark fringes superimposed on the three-dimensional image whose pattern is modeled to find E directly. In the laboratory, the holographic technique determined E on rock and metal samples to an uncertainty better than 10 percent. For example, double exposure holograms of a saw-cut sample of dolomitic marlstone gave an E of 16.8 ± 2.8 GPa in agreement with 17.2 ± 2.0 GPa predicted by published density-modulus relationships. Field tests of a holographic tool in a horizontal mine pillar borehole gave in-situ Es which range from 26.9 to 36.0 GPa. Although these data could be interpreted as localized elastic heterogeneity within the rock mass, elastic anisotropy of the rock is a possible explanation for this variation

“What? That’s for Old People, that.” Home Adaptations, Ageing and Stigmatisation: A Qualitative Inquiry

Older people, even those living with long-term conditions or poor mobility, can be supported to live well at home, through adapting their home to meet changing need. Installing home adaptations, from grab rails to walk in shower rooms, is cost effective, may prevent falls, reduce social isolation and improve self confidence. Despite austerity cuts to public spending, the UK government increased home adaptations’ funding. However, not much is known about older people’s experiences and understanding of acquiring and living with home adaptations and uptake of home adaptations could be improved. Using wearable camera and face to face interview data, this qualitative study explored a diverse group of older people’s retrospective experiences (n = 30). Focus group discussions were also carried out with a wide range of professionals involved in the provision of home adaptations (n = 39). Findings suggest people may delay having adaptations, because of perceived stigmatising associations with decline and vulnerability. As delaying the installation of home adaptations until crisis point is known to reduce their effectiveness, such associations need to be challenged

A 3D Dust Map Based on Gaia, Pan-STARRS 1 and 2MASS

We present a new three-dimensional map of dust reddening, based on Gaia parallaxes and stellar photometry from Pan-STARRS 1 and 2MASS. This map covers the sky north of a declination of -30 degrees, out to a distance of several kiloparsecs. This new map contains three major improvements over our previous work. First, the inclusion of Gaia parallaxes dramatically improves distance estimates to nearby stars. Second, we incorporate a spatial prior that correlates the dust density across nearby sightlines. This produces a smoother map, with more isotropic clouds and smaller distance uncertainties, particularly to clouds within the nearest kiloparsec. Third, we infer the dust density with a distance resolution that is four times finer than in our previous work, to accommodate the improvements in signal-to-noise enabled by the other improvements. As part of this work, we infer the distances, reddenings and types of 799 million stars. We obtain typical reddening uncertainties that are ~30% smaller than those reported in the Gaia DR2 catalog, reflecting the greater number of photometric passbands that enter into our analysis. Our 3D dust map can be accessed at https://doi.org/10.7910/DVN/2EJ9TX or through the Python package "dustmaps," and can be queried interactively at http://argonaut.skymaps.info. Our catalog of stellar parameters can be accessed at https://doi.org/10.7910/DVN/AV9GXO.Comment: 43 pages, 19 figure

Optimization Of Detergent-Mediated Reconstitution Of Influenza A M2 Protein Into Proteoliposomes

We report the optimization of detergent-mediated reconstitution of an integral membrane-bound protein, full-length influenza M2 protein, by direct insertion into detergent-saturated liposomes. Detergent-mediated reconstitution is an important method for preparing proteoliposomes for studying membrane proteins, and must be optimized for each combination of protein and membrane constituents used. The purpose of the reconstitution was to prepare samples for site-directed spin-labeling electron paramagnetic resonance (SDSL-EPR) studies. Our goals in optimizing the protocol were to minimize the amount of detergent used, reduce overall proteoliposome preparation time, and confirm the removal of all detergent. The liposomes were comprised of (1-palmitoyl-2-oleyl-sn-glycero-phosphocholine (POPC) and 1-palmitoyl-2-oleyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG), and the detergent octylglucoside (OG) was used for reconstitution. Rigorous physical characterization was applied to optimize each step of the reconstitution process. We used dynamic light scattering (DLS) to determine the amount of OG needed to saturate the preformed liposomes. During detergent removal by absorption with Bio-Beads, we quantified the detergent concentration by means of a colorimetric assay, thereby determining the number of Bio-Bead additions needed to remove all detergent from the final proteoliposomes. We found that the overnight Bio-Bead incubation used in previously published protocols can be omitted, reducing the time needed for reconstitution. We also monitored the size distribution of the proteoliposomes with DLS, confirming that the size distribution remains essentially constant throughout the reconstitution process

Physical inactivity rapidly alters glycemic control in young, lean, previously active volunteers [abstract]

Postprandial hyperglycemia is a better predictor of cardiovascular disease and all cause mortality than fasting blood glucose or hemoglobin A1c. Physical inactivity is associated with insulin resistance and cardiovascular disease. To determine whether transitioning from a high to low level of physical activity affects glycemic control, we equipped young (30 [plus or minus] 1 y), lean (24 [plus or minus] 1 kg-m-2), healthy, physically active (>10,000 steps-d-1) volunteers (N=10) with continuous blood glucose monitors for 3 days during separate ACTIVE (habitual physical activity) and INACTIVE ([less than or equal to]5,000 steps-d-1) phases (diet replicated across phases)