Under stable atmospheric conditions, the zenithal brightness of the urban sky varies throughout the night following the time course of the anthropogenic emissions of light. Different types of artificial light sources (e.g. streetlights, residential, and vehicle lights) present specific time signatures, and this feature makes it possible to estimate the amount of sky brightness contributed by each one of them. Our approach is based on transforming the time representation of the zenithal sky brightness into a modal coefficients one, in terms of the time course signatures of the sources. The modal coefficients, and hence the absolute and relative contributions of each type of source, can be estimated from the measured brightness by means of linear least squares fits. A method for determining the time signatures is described, based on wide-field time-lapse photometry of the urban nightscape. Our preliminary results suggest that artificial light leaking out of the windows of residential buildings may account for a significant share of the timevarying part of the zenithal sky brightness, whilst the contribution of the vehicle lights seems to be significantly smaller.

BackgroundThe NHS has a target of cutting its carbon dioxide (CO 2 ) emissions by 80% below 1990 levels by 2050. Travel comprises 17% of the NHS carbon footprint. This carbon footprint represents the total CO 2 emissions caused directly or indirectly by the NHS. Patient journeys have previously been planned largely without regard to the environmental impact. The potential contribution of 'avoidable' journeys in primary care is significant. AimTo investigate the carbon footprint of patients travelling to and from a general practice surgery, the issues involved, and potential solutions for reducing patient travel. Design and settingA mixed methods study in a medium-sized practice in Yorkshire. MethodDuring March 2012, 306 patients completed a travel survey. GIS maps of patients' travel (modes and distances) were produced. Two focus groups (12 clinical and 13 non-clinical staff) were recorded, transcribed, and analysed using a thematic framework approach. ResultsThe majority (61%) of patient journeys to and from the surgery were made by car or taxi; main reasons cited were 'convenience', 'time saving', and 'no alternative' for accessing the surgery. Using distances calculated via ArcGIS, the annual estimated CO 2 equivalent carbon emissions for the practice totalled approximately 63 tonnes. Predominant themes from interviews related to issues with systems for booking appointments and repeat prescriptions; alternative travel modes; delivering health care; and solutions to reducing travel. ConclusionThe modes and distances of patient travel can be accurately determined and allow appropriate carbon emission calculations for GP practices. Although challenging, there is scope for identifying potential solutions (for example, modifying administration systems and promoting walking) to reduce 'avoidable' journeys and cut carbon emissions while maintaining access to health care.

From 1996 to 2015 sixteen main belt asteroids were discovered exhibiting cometary activity (less than one per year), all of them during searches at the telescope. In this work we will explore another way to discover them. We reduced 192016 magnitude observations of 165 asteroids of the Themis family, using data from the astrometric-photometric database of the Minor Planet Center, MPCOBS, and measuring the absolute magnitudes from the phase plots. 25 objects of 165 (15.2%), exhibited bumps or enhancements in brightness that might indicate low level cometary activity. Since activity repeats at the same place in different orbits and in many occasions is centered at perihelion, activity might be due to water ice sublimation. As of September 2016, there are 717768 asteroids listed in the Minor Planet files. If we assume that we do not have any false positives and the above percentage can be extrapolated to the whole Main Belt, the number of potentially active asteroid gets to the very large number of ~111.000. This number is much larger than the ones predicted in previous surveys and indicates one of three scenarios: A) there are many false positives in our detections and the real number of active asteroid is much smaller than we found. This would be tantamount to saying that the MPC astrometric-photometric database is only astrometric and not photometric, invalidating absolute magnitude determinations based on this database. B) The location of active asteroids is restricted to the Themis family and an extrapolation to the whole belt is not possible. Or C) there are few false positives in our candidates and the main belt actually contains many low level active asteroids undetected by current surveys. Case C) would imply that the main belt is not a field of bare rocks but a graveyard of extinct comets, changing our current paradigm of the main belt. So it is of the outmost importance to verify observationally our candidates, and determine which of these scenarios is valid.

The development of third-generation biofuels from microalgae has been extensively researched over the last few years. Hydrothermal liquefaction (HTL) is a promising route for producing bio-oils from wet algae. The major drawback in HTL is the high temperature and high pressure that result in the high capital cost of the process. To make HTL an economical process for bio-oil production, the temperature and pressure should be reduced, which can be achieved by adding alcohol to water for HTL. The efficiency of the HTL process can also be improved by using a suitable heterogeneous catalyst with additional modifications. In this work, we investigated the effect of dielectric barrier discharge (DBD) plasma (argon and hydrogen plasma) modified zeolite Y as catalysts on the yield and quality of bio-oils produced in a hydrogen atmosphere versus air at different reaction times (0 and 15 min) and temperatures (240 and 250 °C). The mixture of solvents (50 vol % water and 50 vol % ethanol) was used in HTL to increase the yield and quality of bio-oils. Two sequential extractions were used to extract bio-oils from HTL products using dichloromethane. Different analytical techniques, such as thermal gravimetric analysis, elemental analysis, and gas chromatography−mass spectrometry, were used to understand the physicochemical properties of the bio-oils and for the determination of the higher heating value (HHV). The introduction of DBD plasma to modify zeolite Y improved the bio-oil quality and yield from HTL processes. The H 2 plasma modified catalyst enhanced the bio-oil yield at 240 °C from 46.83 ± 1.48% (240-0-H 2 -ZY) to 50.04 ± 0.88% (240-0-H 2 -ZY-HP) and from 50.24 ± 1.96% (250-0-H 2 -ZY) to 53.01 ± 0.73% (250-0-H 2 -ZY-HP) at 250 °C. The argon plasma modified catalyst reduced N-containing compounds from 29.42% (240-0-H 2 -ZY) to 2.94% (240-0-H 2 -ZY-AP) and decreased O-containing compounds from 4.02% (240-0-H 2 -ZY) to 1.38% (240-0-H 2 -ZY-AP) at 240 °C.

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