A discussion of the solution for the motion of Pluto

In a previous paper, a semi-analytical solution for the long-term motion of Pluto was presented. The present paper contains: (1) a comparison of the present solution with the solution by Williams and Benson; (2) a discussion of the effect of the near resonance between Pluto and Uranus; and, (3) a calculation of the librational period of the eccentricity, inclination and perihelion.The semi-analytical solution is shown to agree very closely with the long-term solution for Pluto obtained by Williams and Benson using numerical integration of the averaged equations of motion. A small difference between the two solutions is attributed to neglecting the eccentricity and inclination of Neptune in the semi-analytical solution.     

Optical dating and soil micromorphology at MacCauley's Beach,New South Wales,Australia

The ability to position landscapes in a context of time and space is a particular goal of Quaternary science research. The lack of context for dating samples published previously for MacCauley's Beach, an important site for the reconstruction of Australian sea levels, warranted a re‐evaluation of both the site stratigraphy and chronology. In this study, we combined optically stimulated luminescence (OSL) dating of sedimentary quartz grains and soil micromorphology of the same samples to improve our understanding of the depositional history and chronology of the sediments. This combination allowed the contextualization of samples not only in time and space, but also in terms of their depositional histories. The latter is important in OSL dating, where pre‐, syn‐ and post‐depositional processes can all influence the accuracy and precision of the final age estimates. The sediment profile at MacCauley's Beach is made up of three major units. The basal mottled mud layer has undergone extensive pedogenesis since deposition, and only a minimum age of 14.7 ± 2.7 ka could be calculated. The overlying grey mud, with OSL ages from the bottom and top of the unit of 10.0 ± 0.7 and 7.7 ± 0.5 ka, respectively, shows evidence of soil structure collapse. This unit correspond to the onset of the mid‐Holocene sea‐level high stand for this region. The overlying sand layer was first deposited at 7.5 ± 0.4 ka, with deposition continuing beyond 6.6 ± 0.4 ka. Not only does the chronology presented constrain the timing of deposition (and the extent of post‐depositional processes) at MacCauley's Beach, but the methodological approach used here can be applied to any site to aid in the interpretation of formation processes and assess their influence on OSL age determination. Copyright © 2014 John Wiley & Sons, Ltd.     

Significance of vertical flux as a sink for surface water DMSP and as a source for the sediment surface in coastal zones of northern Europe

In April 1997 and 1998 the significance of sedimentation as a sink for epipelagic dimethylsulphoniopropionate (DMSP) production and as a source for marine sediments was reassessed using a newly designed sediment trap. The behaviour of the traps in immersion was monitored continuously and the collection efficiency was evaluated with ²³⁴Th measurements. Net DMS(P) fluxes were corrected for some physical and biological losses during the whole sedimentation process providing reliable estimates of gross DMSP fluxes. It is shown that daily losses by sedimentation account for between 0.1% and 16% of seawater particulate DMSP (DMSPp) standing stocks, and between 3% and 75% of daily DMSPp production. In the Malangen fjord we observed temporal increases of DMSP production and standing stocks which resulted also in increases of DMSP vertical fluxes and DMS(P) concentrations at the sediment surface. This result illustrates how tight the coupling can be between pelagos and benthos, and confirms that DMS(P) concentration in the sediment was a reliable diagnostic indicator of vertical export from overlying waters in Malangen fjord. In Ullsfjord, however, DMS(P) concentrations in the sediment were poorly indicators of Phaeocystis pouchetii export during the early stage of growth of a bloom. The high load of DMS(P) in Balsfjord's sediments could neither be attributed to local vertical sedimentation nor to short-term lateral advection of fresh DMSP-containing phytoplanktonic material, and provides indication that this tracer sometimes also can be misleading. The highest loads of DMS(P) in sediments and the fastest rates of sedimentation occurred in the Southern Bight of the North Sea.     

Temporary labour migration and sustainable post-conflict return in Sierra Leone

Economic and social development indicators suggest that the small West African state of Sierra Leone is among the poorest countries in the world. Sierra Leone’s economy and quality of life deteriorated rapidly during a decade of political instability and civil war in the 1990s, when many people fled their homes and abandoned their livelihoods due to the rebel insurgency. This paper examines the post-war reconstruction scenario in Sierra Leone and presents recent evidence from two rural communities in the Eastern Province that were badly affected by the conflict. The paper considers the links between the farming and diamond mining sectors, which, despite severe dislocation during the conflict period, have proved to be remarkably resilient. It is argued that seasonal labour mobility associated with this dual economy has not only continued to be a key ingredient in sustaining livelihood portfolios, but is actually an essential pre-condition for the creation of an enabling environment for sustainable post-conflict return.

Ultra-wideband radar studies of steep crested waves with scanning laser measurements of wave slope profiles

We report results of ultra wide-band radar sea spike experiments using steep and weakly breaking non-linear water surface features in a wave tank. To generate these features we used a 1 s paddle wave and wind waves for a sequence of wind speeds. A scanning laser was used to measure synchronously the surface slope profile across 12 cm along the wave propagation direction once per radar pulse. A time domain reflectometer (TDR) radar transmitted short horizontally polarized pulses at X-band, several hundred picoseconds long, to give a range resolution of 10 cm. A radar range of 36 cm was digitally sampled so that surface feature echoes could be tracked through the area continuously with 5 ms temporal resolution with each instrument. We report results considering the wave slope component in the propagation direction and the corresponding curvature component. For the conditions studied, two types of features which produce sea spike radar echoes were generated–a non-linear feature near the crest front of the wind wave, caused by extreme steepening as a result of the passage of the paddle wave, and a steepened blocked wind wave in the trough of the paddle wave, caused by the local orbital current of the 1 s wave being nearly equal to and opposite the phase velocity of the wind wave.     

Generalised observations of wave characteristics on near‐horizontal shore platforms: Synthesis of six case studies from the North Island,New Zealand

Most field studies of wave processes on shore platforms in front of eroding cliffs focus on a single site, revealing aspects of wave dynamics at that location. Here, we analyse data from six platforms around northeastern New Zealand and describe the fundamental control of shore platform width, gradient and elevation on wave processes, including greater attenuation of short‐period waves at lower tidal stages and increases in longer period wave energy towards the cliff toe. These data suggest that empirical formulae developed from coral‐reef environments provide better predictions of wave height on platforms than formulae currently used in shore platform models.     

Probing the physics of interacting galaxies

The morphological and velocity structures in the gaseous (HI and CO) and stellar components of two interacting systems are examined. Both Arp 140 and Arp 104 reveal extended tidal tails in the HI. The Hα and FIR fluxes of Arp 140 yield similar SFR of ∼ 0.8 M_⊙ yr^-1. In contrast the Hα flux of Arp 104 yields a SFR of ∼ 0.05 M_⊙ yr^-1, ∼ 20 times smaller than that obtained from the FIR flux. Spectra were used to examine the changing velocity of atomic and molecular gas in NGC 5218 (Arp 104). The atomic and molecular gas were found to be dynamically similar with comparable velocities and velocity widths across the galaxy; consistent with the two phases responding similarly to the interaction, or enhanced HI to CO conversion in the centre of the galaxy. This revised version was published online in August 2006 with corrections to the Cover Date.