Book Reviews

Book Review 1Book Title: Early Life Histories of Fishes: New Developmental, Ecological and Evolutionary PerspectivesBook Author: Edited by E.K. BalonDr W. Junk, Dordrecht. 280 pp.Book Review 2Book Title: Comparative Aspects of Extracellular Acid-base BalanceBook Author: J.P. TruchotSpringer, 1987. 248 pp. 51 figures.Book Review 3Book Title: Insect Flight: Dispersal and MigrationBook Author: Edited by W. DanthanarayanaSpringer-Verlag, Berlin, 1986. 289 pp.Book Review 4Book Title:  The Mammalian Herbivore Stomach. Comparative Anatomy, Function and EvolutionBook Author: Peter LangerGustav Fischer, Stuttgart, 1988. 557 pages, 246 figures and 72 tablesBook Review 5Book Title:  Biology of the Integument. Vol. 2: VertebratesBook Authors: Edited by J. Bereiter-Hahn, A.G. Matoltsy & K.S. RichardsSpringer, Berlin, 1986. 855 pp.Book Review 6Book Title:  Advances in the Biology of Turbellarians and related PlatyhelminthesBook Author: Edited by Seth TylerDr. W. Junk Publishers, 1986. 357 pages; 253 figuresBook Review 7Book Title: Evolutionary Physiological EcologyBook Author: Edited by P. CalowCambridge University Press, Cambridge. 239 pp.Book Review 8Book Title: DragonfliesBook Author: Peter L. MillerCambridge University Press, Cambridge, New York and Melbourne, 1987. 84 pp

Minimum Energy Configurations in the NN-Body Problem and the Celestial Mechanics of Granular Systems

Minimum energy configurations in celestial mechanics are investigated. It is shown that this is not a well defined problem for point-mass celestial mechanics but well-posed for finite density distributions. This naturally leads to a granular mechanics extension of usual celestial mechanics questions such as relative equilibria and stability. This paper specifically studies and finds all relative equilibria and minimum energy configurations for $N=1,2,3$ and develops hypotheses on the relative equilibria and minimum energy configurations for $N\gg 1$ bodies.Comment: Accepted for publication in Celestial Mechanics and Dynamical Astronom

Polynomial-Time Amoeba Neighborhood Membership and Faster Localized Solving

We derive efficient algorithms for coarse approximation of algebraic hypersurfaces, useful for estimating the distance between an input polynomial zero set and a given query point. Our methods work best on sparse polynomials of high degree (in any number of variables) but are nevertheless completely general. The underlying ideas, which we take the time to describe in an elementary way, come from tropical geometry. We thus reduce a hard algebraic problem to high-precision linear optimization, proving new upper and lower complexity estimates along the way.Comment: 15 pages, 9 figures. Submitted to a conference proceeding

Preliminary observations of tag shedding, tag reporting, tag wounds, and tag biofouling for raggedtooth sharks (Carcharias taurus) tagged off the east coast of South Africa

Mark-recapture models do not distinguish how ‘‘deaths’’ accrue to marked animals in the population. If animals lose their tags, then recaptures will be fewer than expected and estimates of survival will be underestimated (Arnason and Mills, 1981; McDonald et al., 2003). Similarly, if the non-reporting rate is unknown and assumed to be negligible, as is the case in some tagging studies (e.g. Cliff et al., 1996, for white sharks Carcharodon carcharias), the probability of capture can be underestimated. The effects of both these problems, inherent in cooperative tagging programmes, lead to too few tagged fish being recovered, with a positive bias on the estimation of population size. These effects are most pronounced when capture probability is low and fewer tags are available for recapture (McDonald et al., 2003)

Morphological effects of spatially varying grain size and bed roughness in rivers

Many morphological models that are in use today, make use of spatially constant grain sizes and bed roughness. Application of this spatially constant grain size and bed roughness is not a correct representation of reality. When making use of actually measured grain sizes, the prediction of the morphological changes does not necessarily improve. Linear analyses of the application of spatially varying grain sizes show that the spatial variation of grain sizes can have much impact on the bed topography in rivers. Two different linear analyses have been conducted by Mosselman & Sloff (1998) and Sieben (2000). One shows a difference in the length and dampening of the bed perturbations due to free excitation. The other shows the existence of a response in the bed topography like a superimposed waveform, due to forced excitation. Implementation of the spatially varying grain size resulted for Olesen's experiment (1985) in effects according to free and forced excitation. For the models of the Waal bend at Nijmegen and Pannerdense Kop, the effects were according to forced excitation. Both linear analyses show morphological effects due to the spatially varying grain size as well as due to spatially varying bed roughness. The spatial variation of the bed roughness should, according to the analyses, have a counteracting morphological effect in regard to the morphological effects of the spatially variation of the grain size. Application of spatially varying bed roughness resulted for Olesen's experiment in effects according to free and forced excitation. For the other two models the implementation of spatially varying bed roughness resulted in effects according to forced excitation. Implementation of a grain size distribution which has reached an equilibrium state leads to a bed level response according to free excitation. While the implementation of a grain size distribution which has not reached an equilibrium, like in rivers with variable discharge, leads to a bed level response according to forced excitation. Implementation of an alluvial bed roughness predictor led to no satisfactory results for Olesen's experiment and the Waal bend at Nijmegen. However, for the model of Pannerdense Kop the results of the computation matched the prototype better than the computation with uniform grain sizes and bed roughness. This was caused by two main effects. The first was a forced excitation due to the spatially varying bed roughness. The second was a change in the sediment distribution at the bifurcation.Civil Engineering and Geoscience

Synthesis of SBW belastingen

The Dutch Water Act (in Dutch: 'Waterwet 2009') stipulates that water boards must assess the quality of their primary water defences every six years. The Statutory Safety Assessment Suite (in Dutch: 'Wettelijk Toetsinstrumentarium', or shortly WTI) prescribes the rules to be applied. The WTI mainly comprises of the Safety Test Regulations (VTV), the Hydraulic Boundary Conditions (HBC) and the underlying Technical Reports and Guidelines. The HBC must be determined and established by the Minister of Transport, Public Works and Water Management every six years. The scope of the SBW-Belastingen project concerns the filling in of the main knowledge gaps in the determination of the HBC, insofar as they fall under one of the four pillars of SBWBelastingen: statistics, physics, probabilistics, uncertainty analysis. This new knowledge is obtained by means of site measurements, laboratory research, models and desk studies. A significant amount of research, covering all four pillars of SBW-Belastingen, has been performed in the period 2008-2010. This synthesis report summarises the main results from the research performed within the framework of SBW-Belastingen during the years 2008-2010. The report will give a general overview of all research topics addressed before the start of SBW-Belastingen as well as a more detailed description of the progress: conclusions and recommendations of the research topics addressed within the framework of SBW-Belastingen in the period 2008-2011. The result of this synthesis is a statement of the performed research so far and a recommendation for research to be performed in the period 2011-2016.SB

Seasonality, behaviour and philopatry of spotted ragged-tooth sharks Carcharias taurus in Eastern Cape nursery areas, South Africa

Spotted ragged-tooth sharks Carcharias taurus occur along the southern and eastern coasts of South Africa. We report on movements of juveniles and adults within a known nursery area on the Eastern Cape coast using  acoustic telemetry. The focus area of the study was Algoa Bay, where six VEMCO VR2 ultrasonic receivers were placed at known shark aggregation sites. An additional receiver was placed at Thunderbolt Reef, approximately 2 km southwest of Cape Recife, the south-western tip of Algoa Bay. Single receivers were also deployed at Port Alfred and East London, some 45 and 170 km north-east of Algoa Bay, respectively.  VEMCO acoustic V16 tags were either surgically implanted (n = 37) or attached externally using dart heads (n = 6) between January 2003 and March 2006. Surgically implanted tags were recorded over multiple months and years, whereas external tags were probably lost shortly after tagging because they were detected for very short periods. Sharks moved extensively between the sites and revisited monitored reefs over time-periods of months and years, demonstrating philopatry. Departures from and arrivals at reefs were more frequently recorded at sunset and sunrise, respectively. Sharks were detected throughout the year but they spent more time at aggregation sites during summer and autumn, indicating seasonal abundance in agreement with previous findings. Movements away from study reefs were attributed to either foraging or movements to other reefs. Despite extensive movements around the bay and beyond, both juveniles and adults exhibited philopatry to the study area over multiple years.Keywords: acoustic telemetry, Algoa Bay, behaviour, migratio