Rotation-stimulated structures in the CN and C3 comae of comet 103P/Hartley 2 around the EPOXI encounter

In late 2010 a Jupiter Family comet 103P/Hartley 2 was a subject of an intensive world-wide investigation. On UT October 20.7 the comet approached the Earth within only 0.12 AU, and on UT November 4.6 it was visited by NASA's EPOXI spacecraft. We joined this international effort and organized an observing campaign. The images of the comet were obtained through narrowband filters using the 2-m telescope of the Rozhen National Astronomical Observatory. They were taken during 4 nights around the moment of the EPOXI encounter. Image processing methods and periodicity analysis techniques were used to reveal transient coma structures and investigate their repeatability and kinematics. We observe shells, arc-, jet- and spiral-like patterns, very similar for the CN and C3 comae. The CN features expanded outwards with the sky-plane projected velocities between 0.1 to 0.3 km/s. A corkscrew structure, observed on November 6, evolved with a much higher velocity of 0.66 km/s. Photometry of the inner coma of CN shows variability with a period of 18.32+/-0.30 h (valid for the middle moment of our run, UT 2010 Nov. 5.0835), which we attribute to the nucleus rotation. This result is fully consistent with independent determinations around the same time by other teams. The pattern of repeatability is, however, not perfect, which is understendable given the suggested excitation of the rotation state, and the variability detected in CN correlates well with the cyclic changes in HCN, but only in the active phases. The revealed coma structures, along with the snapshot of the nucleus orientation obtained by EPOXI, let us estimate the spin axis orientation. We obtained RA=122 deg, Dec=+16 deg (epoch J2000.0), neglecting at this point the rotational excitation.Comment: 9 pages, 10 figures, submitted to Astron. Astrophy

Review of aquaculture and fish consumption in Bangladesh

Fish play a crucial role in the Bangladeshi diet, providing more than 60% of animal source food, representing a crucial source of micro-nutrients, and possessing an extremely strong cultural attachment. Fish (including shrimp and prawn) is the second most valuable agricultural crop, and its production contributes to the livelihoods and employment of millions. The culture and consumption of fish therefore has important implications for national food and nutrition security, poverty and growth. This review examines the current state of knowledge on the aquaculture sector and fish consumption in Bangladesh, based on extensive analysis of secondary sources (including unpublished data unavailable elsewhere), consultation with various experts and specially conducted surveys. The review is comprised of three sections. Section 1 describes the main systems of aquaculture production in terms of their technical and social characteristics and outputs. Section 2 addresses issues relating to seed and feed. The final section analyses fish consumption patterns and demand, and attempts to estimate the volumes of fish produced from a range of sources.Food fish, Aquaculture, Food consumption, Fish consumption, Pond culture, Rice field aquaculture, Bangladesh,

The Increasing Rotation Period of Comet 10P/Tempel 2

We imaged comet 10P/Tempel 2 on 32 nights from 1999 April through 2000 March. R-band lightcurves were obtained on 11 of these nights from 1999 April through 1999 June, prior to both the onset of significant coma activity and perihelion. Phasing of the data yields a double-peaked lightcurve and indicates a nucleus rotational period of 8.941 +/- 0.002 hr with a peak-to-peak amplitude of ~0.75 mag. Our data are sufficient to rule out all other possible double-peaked solutions as well as the single- and triple- peaked solutions. This rotation period agrees with one of five possible solutions found in post-perihelion data from 1994 by Mueller and Ferrin (1996, Icarus, 123, 463-477), and unambiguously eliminates their remaining four solutions. We applied our same techniques to published lightcurves from 1988 which were obtained at an equivalent orbital position and viewing geometry as in 1999. We found a rotation period of 8.932 +/- 0.001 hr in 1988, consistent with the findings of previous authors and incompatible with our 1999 solution. This reveals that Tempel 2 spun-down by ~32 s between 1988 and 1999 (two intervening perihelion passages). If the spin-down is due to a systematic torque, then the rotation period prior to perihelion during the 2010 apparition is expected to be an additional 32 s longer than in 1999.Comment: Accepted by The Astronomical Journal; 22 pages of text, 3 tables, 6 figure

Radioactive metals disposal and recycling impact modelling

Screening life cycle assessment models developed to investigate hypothetical disposal and recycling options for the Windscale Advanced Gas-cooled Reactor heat exchangers were used to generate more complex models addressing the main UK radioactive metals inventory. Both studies show there are significant environmental advantages in the metals recycling promoted by the current low level waste disposal policies, strategies and plans. Financial benefits from current metals treatment options are supported and offer even greater benefits when applied to the UK radioactive metals inventory as a whole

Spitzer Space Telescope Observations of the Nucleus of Comet 103P/Hartley 2

We have used the Spitzer Space Telescope InfraRed Spectrograph (IRS) 22-μm peakup array to observe thermal emission from the nucleus and trail of comet 103P/Hartley 2, the target of NASA’s Deep Impact Extended Investigation (DIXI). The comet was observed on UT 2008 August 12 and 13, while 5.5 AU from the Sun. We obtained two 200 frame sets of photometric imaging over a 2.7 hr period. To within the errors of the measurement, we find no detection of any temporal variation between the two images. The comet showed extended emission beyond a point source in the form of a faint trail directed along the comet’s antivelocity vector. After modeling and removing the trail emission, a NEATM model for the nuclear emission with beaming parameter of 0.95 ± 0.20 indicates a small effective radius for the nucleus of 0.57 ± 0.08 km and low geometric albedo 0.028 ± 0.009 (1σ). With this nucleus size and a water production rate of 3 × 10^(28) molecules s^(-1) at perihelion, we estimate that ~100% of the surface area is actively emitting volatile material at perihelion. Reports of emission activity out to ~5 AU support our finding of a highly active nuclear surface. Compared to Deep Impact’s first target, comet 9P/Tempel 1, Hartley 2’s nucleus is one-fifth as wide (and about one-hundredth the mass) while producing a similar amount of outgassing at perihelion with about 13 times the active surface fraction. Unlike Tempel 1, comet Hartley 2 should be highly susceptible to jet driven spin-up torques, and so could be rotating at a much higher frequency. Since the amplitude of nongravitational forces are surprisingly similar for both comets, close to the ensemble average for ecliptic comets, we conclude that comet Hartley 2 must have a much more isotropic pattern of time-averaged outgassing from its nuclear surface. Barring a catastrophic breakup or major fragmentation event, the comet should be able to survive up to another 100 apparitions (~700 yr) at its current rate of mass loss

Lunar scout missions: Galileo encounter results and application to scientific problems and exploration requirements

The Lunar Scout Missions (payload: x-ray fluorescence spectrometer, high-resolution stereocamera, neutron spectrometer, gamma-ray spectrometer, imaging spectrometer, gravity experiment) will provide a global data set for the chemistry, mineralogy, geology, topography, and gravity of the Moon. These data will in turn provide an important baseline for the further scientific exploration of the Moon by all-purpose landers and micro-rovers, and sample return missions from sites shown to be of primary interest from the global orbital data. These data would clearly provide the basis for intelligent selection of sites for the establishment of lunar base sites for long-term scientific and resource exploration and engineering studies. The two recent Galileo encounters with the Moon (December, 1990 and December, 1992) illustrate how modern technology can be applied to significant lunar problems. We emphasize the regional results of the Galileo SSI to show the promise of geologic unit definition and characterization as an example of what can be done with the global coverage to be obtained by the Lunar Scout Missions

Controlled release from zein matrices: Interplay of drug hydrophobicity and pH

Purpose: In earlier studies, the corn protein zein is found to be suitable as a sustained release agent, yet the range of drugs for which zein has been studied remains small. Here, zein is used as a sole excipient for drugs differing in hydrophobicity and isoelectric point: indomethacin, paracetamol and ranitidine. Methods: Caplets were prepared by hot-melt extrusion (HME) and injection moulding (IM). Each of the three model drugs were tested on two drug loadings in various dissolution media. The physical state of the drug, microstructure and hydration behaviour were investigated to build up understanding for the release behaviour from zein based matrix for drug delivery. Results: Drug crystallinity of the caplets increases with drug hydrophobicity. For ranitidine and indomethacin, swelling rates, swelling capacity and release rates were pH dependent as a consequence of the presence of charged groups on the drug molecules. Both hydration rates and release rates could be approached by existing models. Conclusion: Both the drug state as pH dependant electrostatic interactions are hypothesised to influence release kinetics. Both factors can potentially be used factors influencing release kinetics release, thereby broadening the horizon for zein as a tuneable release agent

Morphology and time variability of Io's visible aurora

Clear-filter imaging of Io during the Galileo nominal and extended missions recorded diffuse auroral emissions in 16 distinct observations taken during 14 separate eclipses over a two year period. These images show that the morphology and time variability of the visible aurora have several similarities to Io's far ultraviolet emissions. The orbital leading hemisphere of Io is consistently brighter than the trailing hemisphere, probably due to a greater concentration of torus electrons in the wake region of the satellite. The locations of the polar limb glow and the bright equatorial glows appear to correlate with Io's System III longitude. Unlike the far ultraviolet emissions, the visible aurorae are enhanced near actively venting volcanic plumes, probably because of molecular emission by SO_2

Exploring young people's and youth workers' experiences of spaces for ‘youth development’: creating cultures of participation

The paper focuses on the emergence of ‘positive youth development’ and its impact on older, more established practices of working with young people, such as youth work. Drawing on ethnographic fieldwork in England between 2004 and 2006, in particular young people's and youth workers' accounts of participating in youth work, the analysis engages with the social spaces in which youth work takes place and asks key questions about why young people might participate in youth spaces, what they get out of participating and how such spaces can promote cultures of participation. The analysis shows that such spaces provide young people and their communities with biographical continuity and time becomes a key component for sustaining such spaces. The argument is made for a more nuanced understanding of what young people get out of their participation in youth spaces, and for an epistemological approach to youth praxis that embraces the messiness and inequalities of lived experience