In 1998, evidence was provided suggesting that an apparent 15% decline in domestic travel estimated from the Canadian Travel Surveys (CTS) of 1994, 1996, and 1997 was possibly misleading. This decline could actually be the result of methodological changes in the survey rather than a change in travel behaviour. Here, realistic assumptions and a simple computational method are utilized to demonstrate that change in bias may account for the drop in estimated trips. The analysis depends on a trip recall salience scale. Use of this scale allows correction for an under-reporting bias arising from reduced trip recall rates for low-salience trips. When the 1996 and 1997 CTS data are corrected, estimates of change in total trips are near zero. This finding corresponds to perceptions within the tourism industry. The bias correction methodology is applicable to other large surveys involving recall of past behaviour in which multiple events are recalled.
Samples from the lower Cape Lamb Member, López de Bertodano Formation, Cape Lamb, Vega Island, Antarctic Peninsula have yielded rich and diverse marine palynofloral assemblages. The overall character of the palynofloral assemblages indicate a latest Campanian–earliest Maastrichtian age. Four new dinoflagellate cyst species Canninginopsis ordospinosa sp. nov., Microdinium ? gymnosuturum sp. nov., Phelodinium exilicornutum sp. nov. and Operculodinium radiculatum sp. nov. are described. Certain key dinoflagellate cyst taxa such as Operculodinium radiculatum sp. nov., Manumiella n. sp. 3 and Isabelidinium cretaceum allow a correlation of the lower Cape Lamb Member with the upper palynomorph zone 1/lower zone 2 on nearby Seymour Island.
Regional structural synthesis together with 2D forward and reverse flexural isostatic basin modelling techniques have been used to investigate the extensional and subsidence history of the southern part of the Porcupine Basin. Two structural interpretations of seismic line GSP97-19 have been considered: (1) a Mid-Late Jurassic rift basin based upon seismic interpretation of well-defined tilted fault blocks, with subsidence modelling of the thick overlying sediment section predicting high lithosphere stretching factors of up to β = 6; (2) a Mid-Jurassic-Early Cretaceous rift responsible for a thick Barremian-Aptian synrift sequence within the basin centre resulting in reduced maximum lithospheric stretching factors of β = 2.3. The variance in published estimates of crustal thickness beneath the basin cannot distinguish between these scenarios. A comparison between stretching factors and the amount of observable upper-crustal faulting suggests that depth-dependent lithospheric stretching may be a feature of the basin, as in other sedimentary basins along the Atlantic margin, and is directly associated with the onset of Cretaceous plate break-up in the Atlantic.
The Fulmar Field is located on the southwestern margin of the Central Graben in Blocks 30/16 and 30/11 b of the UK sector of the North Sea. The Fulmar Field was discovered 1975 and began producing in 1982 . Currently (2000 the field produces at a rate of 8000 BOPD at a watercut above 90% mainly through the process of rinsing of residual oil. Total STOIIP is 822 MMBBL and ultimate recovery is 567 MMBBL ofoil and 342 BSCF of wet gas. As of the end of 1999, 547 MMSTB ofoil and 325 BSCF of wet gas had been produced. The high recovery factor (69%) of the field is thought to be linked to the combination of well density, large length of reservoir perforated, excellent reservoir quality, sweep by water injection, good pressure support and oil stripping from a secondary gas cap formed early in field life.The Fulmar Field is a small triangular, partly eroded domal anticline with steeply dipping flanks, located on a fault terrace within the western margin of the South West Central Graben at a depth between 9900 and 11 500 ft TVDss. The field has been shaped by three major tectonic processes: (1) halokinesis, (2) syndepositional reactivation of Caledonian basement faults; and (3) syndepositional through post-depositional displacements along the nearby Auk Horst Boundary Fault. The reservoir consists of thick Upper Jurassic, shallow marine, very bioturbated sandstones of the Fulmar Formation overlain by the deeper marine Ribble Sands interbedded within the Kimmeridge Clay Formation. Reservoir seal is provided by the Kimmeridge Clay in the west and Upper Cretaceous chalks which unconformably overlie the Fulmar Formation in the east. The reservoir section has been lithostratigraphically subdivided into six reservoir units and 24 sub-units. Integration of bio-and lithostratigraphic data has led to a sequence stratigraphic model of the Jurassic succession in the Fulmar Field. In total four depositional sequences are identified, which progressively onlap Triassic basement towards the southwest. The older Jurassic sequences are characterized by rapid progradation of shoreface sands, whereas aggradation of thick sediment packages is typical of the younger intervals. This change of depositional architecture is linked to syndepositional reactivation of basement faults. Major transgressive intervals form intra-reservoir barriers or baffles to flow. Facies changes (Mersey-Clyde Sands) from proximal to distal facies are abrupt and are also linked to basement faults.
Two methods of estimating the variance of the estimate of catch per unit effort are compared empirically here. The second method, an application of the Jackknife estimator proved to be the overall best technique due to its generality. In addition the Jackknife method provides means for the estimation of confidence intervals.Key words: catch per unit effort, variance estimation, Jackknife estimator
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