38 research outputs found

    (1173) Anchises - Thermophysical and Dynamical Studies of a Dynamically Unstable Jovian Trojan

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    We have performed detailed thermophysical and dynamical modelling of Jovian Trojan (1173) Anchises. Our results reveal a most unusual object. By examining observational data taken by IRAS, Akari and WISE between 11.5 and 60 microns, along with variations in its optical lightcurve, we find Anchises is most likely an elongated body, with an axes-ratio of ~1.4. This yields calculated best-fit dimensions of 170x121x121km (an equivalent diameter of 136+18/-11km). We find the observations are best fit by Anchises having a retrograde sense of rotation, and an unusually high thermal inertia (25 to 100 Jm-2s-0.5K-1). The geometric albedo is found to be 0.027 (+0.006/-0.007). Anchises therefore has one of the highest published thermal inertias of any object larger than 100km in diameter, at such large heliocentric distances, and is one of the lowest albedo objects ever observed. More observations are needed to see if there is a link between the very shallow phase curve, with almost no opposition effect, and the derived thermal properties for this large Trojan asteroid. Our dynamical investigation of Anchises' orbit has revealed it to be dynamically unstable on timescales of hundreds of Myr, similar to the unstable Neptunian Trojans 2001 QR322 and 2008 LC18. Unlike those objects, we find that Anchises' dynamical stability is not a function of its initial orbital elements, the result of the exceptional precision with which its orbit is known. This is the first time that a Jovian Trojan has been shown to be dynamically unstable, and adds weight to the idea that planetary Trojans represent a significant ongoing contribution to the Centaur population, the parents of the short-period comets. The observed instability does not rule out a primordial origin for Anchises, but when taken in concert with the result of our thermophysical analysis, suggest that it would be a fascinating target for future study.Comment: 5 figures, 3 tables, accepted for publication in Monthly Notices of the Royal Astronomical Societ

    Does device matter? Impacts of food-specific inhibition training on food choice, liking and approach bias when delivered by smartphone or computer.

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    Food-specific inhibition training (FSIT) requires users to inhibit responses to energy-dense (ED) food stimuli within a reaction time game. FSIT reduces choice and liking of ED foods. Research with the public shows larger effects when FSIT is delivered by computer versus smartphone. This pre-registered study is the first to compare computer-FSIT versus smartphone-FSIT in a controlled setting. Three-hundred-and-thirty-one adults were randomised to computer-FSIT, smartphone-FSIT or non-food control training (computer-delivered). In session 1, participants completed baseline measures of impulsive food choice, food approach bias (approach/avoid implicit association test), and food liking ratings, before completing eight minutes of FSIT/control training. In session 2, participants repeated the same training task, followed by the same measures of food choice, approach bias and liking. We hypothesised that FSIT groups would show healthier food choices, lower ED food liking, and reduced ED food approach bias at post-training compared to control. We expected no statistically significant differences between the two FSIT groups. Post-exclusions, data for 259 participants was analysed. Contrary to predictions, there was no evidence of significant group differences on any of the outcome measures. Baseline measures suggest participants already showed high approach to healthy foods, which may explain these null results

    Comet P/2010 TO20 LINEAR-Grauer as a Mini-29P/SW1

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    Discovered in October 2010 by the LINEAR survey, P/2010 TO20 LINEAR-Grauer (LG) was initially classified as an inert Jupiter Trojan. Subsequent observations obtained in October 2011 revealed LG to be a Jupiter-family comet. LG has one of the largest perihelia (q=5.1 AU) and lowest eccentricities (e=0.09) of the known JFCs. We report on observations of LG taken on 29 October 2011 and numerical simulations of its orbital evolution. Analysis of our data reveals that LG has a small nucleus (<3 km in radius) with broadband colours (B-R=0.99+/-0.06 mag, V-R=0.47+/-0.06 mag) typical of JFCs. We find a model dependent mass-loss rate close to 100 kg/s, most likely powered by water-ice sublimation. Our numerical simulation indicate that the orbit of LG is unstable on very short (10 to 100 yr) timescales and suggest this object has recently evolved into its current location from a more distant, Centaur-type orbit. The orbit, dynamics and activity of LG share similarities with the well known case of comet 29P/Schwassmann-Wachmann 1.Comment: 10 pages, 12 Figures, 5 Tables, accepted for publication on MNRA

    Translational models for vascular cognitive impairment: a review including larger species.

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    BACKGROUND: Disease models are useful for prospective studies of pathology, identification of molecular and cellular mechanisms, pre-clinical testing of interventions, and validation of clinical biomarkers. Here, we review animal models relevant to vascular cognitive impairment (VCI). A synopsis of each model was initially presented by expert practitioners. Synopses were refined by the authors, and subsequently by the scientific committee of a recent conference (International Conference on Vascular Dementia 2015). Only peer-reviewed sources were cited. METHODS: We included models that mimic VCI-related brain lesions (white matter hypoperfusion injury, focal ischaemia, cerebral amyloid angiopathy) or reproduce VCI risk factors (old age, hypertension, hyperhomocysteinemia, high-salt/high-fat diet) or reproduce genetic causes of VCI (CADASIL-causing Notch3 mutations). CONCLUSIONS: We concluded that (1) translational models may reflect a VCI-relevant pathological process, while not fully replicating a human disease spectrum; (2) rodent models of VCI are limited by paucity of white matter; and (3) further translational models, and improved cognitive testing instruments, are required

    Multi-campaign ship and aircraft observations of marine cloud condensation nuclei and droplet concentrations

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    In-situ marine cloud droplet number concentrations (CDNCs), cloud condensation nuclei (CCN), and CCN proxies, based on particle sizes and optical properties, are accumulated from seven field campaigns: ACTIVATE; NAAMES; CAMP2EX; ORACLES; SOCRATES; MARCUS; and CAPRICORN2. Each campaign involves aircraft measurements, ship-based measurements, or both. Measurements collected over the North and Central Atlantic, Indo-Pacific, and Southern Oceans, represent a range of clean to polluted conditions in various climate regimes. With the extensive range of environmental conditions sampled, this data collection is ideal for testing satellite remote detection methods of CDNC and CCN in marine environments. Remote measurement methods are vital to expanding the available data in these difficult-to-reach regions of the Earth and improving our understanding of aerosol-cloud interactions. The data collection includes particle composition and continental tracers to identify potential contributing CCN sources. Several of these campaigns include High Spectral Resolution Lidar (HSRL) and polarimetric imaging measurements and retrievals that will be the basis for the next generation of space-based remote sensors and, thus, can be utilized as satellite surrogates

    Skill-testing chemical transport models across contrasting atmospheric mixing states using radon-222

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    We propose a new technique to prepare statistically-robust benchmarking data for evaluating chemical transport model meteorology and air quality parameters within the urban boundary layer. The approach employs atmospheric class-typing, using nocturnal radon measurements to assign atmospheric mixing classes, and can be applied temporally (across the diurnal cycle), or spatially (to create angular distributions of pollutants as a top-down constraint on emissions inventories). In this study only a short ( \u3c 1-month) campaign is used, but grouping of the relative mixing classes based on nocturnal mean radon concentrations can be adjusted according to dataset length (i.e., number of days per category), or desired range of within-class variability. Calculating hourly distributions of observed and simulated values across diurnal composites of each class-type helps to: (i) bridge the gap between scales of simulation and observation, (ii) represent the variability associated with spatial and temporal heterogeneity of sources and meteorology without being confused by it, and (iii) provide an objective way to group results over whole diurnal cycles that separates \u27natural complicating factors\u27 (synoptic non-stationarity, rainfall, mesoscale motions, extreme stability, etc.) from problems related to parameterizations, or between-model differences. We demonstrate the utility of this technique using output from a suite of seven contemporary regional forecast and chemical transport models. Meteorological model skill varied across the diurnal cycle for all models, with an additional dependence on the atmospheric mixing class that varied between models. From an air quality perspective, model skill regarding the duration and magnitude of morning and evening rush hour pollution events varied strongly as a function of mixing class. Model skill was typically the lowest when public exposure would have been the highest, which has important implications for assessing potential health risks in new and rapidly evolving urban regions, and also for prioritizing the areas of model improvement for future applications

    Clinical response after intradermal immature dendritic cell vaccination in metastatic melanoma is associated with immune response to particulate antigen

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    Metastatic melanoma is poorly responsive to treatment, and immunotherapeutic approaches are potentially beneficial. Predictors of clinical response are needed to identify suitable patients. We sought factors associated with melanoma-specific clinical response following intradermal vaccination with autologous melanoma peptide and particulate hepatitis B antigen (HBsAg)-exposed immature monocyte-derived dendritic cells (MDDC). Nineteen patients with metastatic melanoma received a maximum of 8, 2-weekly vaccinations of DC, exposed to HBsAg in addition to autologous melanoma peptides. A further 3 patients received an otherwise identical vaccine that did not include HBsAg. Patients were assessed 1-2 monthly for safety, disease volume, and cellular responses to HBsAg and melanoma peptide. There was no significant toxicity. Of 19 patients receiving HBsAg-exposed DC, 9 primed or boosted a cellular response to HBsAg, and 10 showed no HBsAg response. HBsAg-specific responses were associated with in vitro T cell responses to melanoma peptides and to phytohemagglutinin (PHA). Zero out of 10 non-HBsAg-responding and 4/9 HBsAg-responding patients achieved objective melanoma-specific clinical responses or disease stabilization- 1 complete and 2 partial responses and I case of stable disease (P=0.018). Development of melanoma-specific cellular immunity and T cell responsiveness to mitogen were greater in the group of patients responding to HBsAg. Therefore stimulation of an immune response to nominal particulate antigen was necessary when presented by melanoma peptide-exposed immature DC, to achieve clinical responses in metastatic melanoma. Since general immune competence may be a determinant of treatment response, it should be assessed in future trials on DC immunotherapy

    Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols

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    Cloud-radiation interactions over the Southern Ocean are not well constrained in climate models, in part due to uncertainties in the sources, concentrations, and cloud-forming potential of aerosol in this region. To date, most studies in this region have reported measurements from fixed terrestrial stations or a limited set of instrumentation and often present findings as broad seasonal or latitudinal trends. Here, we present an extensive set of aerosol and meteorological observations obtained during an austral summer cruise across the full width of the Southern Ocean south of Australia. Three episodes of continental-influenced air masses were identified, including an apparent transition between the Ferrel atmospheric cell and the polar cell at approximately 64span classCombining double low line"inline-formula" &amp;thinsp;S, and accompanied by the highest median cloud condensation nuclei (CCN) concentrations, at 252&amp;thinsp;cmspan classCombining double low line"inline-formula"-3. During the other two episodes, synoptic-scale weather patterns diverted air masses across distances greater than 1000&amp;thinsp;km from the Australian and Antarctic coastlines, respectively, indicating that a large proportion of the Southern Ocean may be periodically influenced by continental air masses. In all three cases, a highly cloud-active accumulation mode dominated the size distribution, with up to 93&amp;thinsp;% of the total number concentration activating as CCN. Frequent cyclonic weather conditions were observed at high latitudes and the associated strong wind speeds led to predictions of high concentrations of sea spray aerosol. However, these modelled concentrations were not achieved due to increased aerosol scavenging rates from precipitation and convective transport into the free troposphere, which decoupled the air mass from the sea spray flux at the ocean surface. CCN concentrations were more strongly impacted by high concentrations of large-diameter Aitken mode aerosol in air masses which passed over regions of elevated marine biological productivity, potentially contributing up to 56&amp;thinsp;% of the cloud condensation nuclei concentration. Weather systems were vital for aerosol growth in biologically influenced air masses and in their absence ultrafine aerosol diameters were less than 30&amp;thinsp;nm. These results demonstrate that air mass meteorological history must be considered when modelling sea spray concentrations and highlight the potential importance of sub-grid-scale variability when modelling atmospheric conditions in the remote Southern Ocean.</p
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