bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparisons of leisure-time physical activity and cardiorespiratory fitness as predictors of all-cause mortality in men and women
Authors: Lee D-C , Sui X , Ortega F B , Kim Y-S , Church T S , Winett R A , Ekelund U , Katzmarzyk P T , Blair S N
Published: April 2010

Objective

To examine the combined associations and relative contributions of leisure-time physical activity (PA) and cardiorespiratory fitness (CRF) with all-cause mortality.

Design

Prospective cohort study.

Setting

Aerobics centre longitudinal study.

Participants

31 818 men and 10 555 women who received a medical examination during 1978–2002.

Assessment of risk factors

Leisure-time PA assessed by self-reported questionnaire; CRF assessed by maximal treadmill test.

Main outcome measures

All-cause mortality until 31 December 2003.

Results

There were 1492 (469 per 10 000) and 230 (218 per 10 000) deaths in men and women, respectively. PA and CRF were positively correlated in men (r=0.49) and women (r=0.47) controlling for age (p<0.001 for both). PA was inversely associated with mortality in multivariable Cox regression analysis among men, but the association was eliminated after further adjustment for CRF. No significant association of PA with mortality was observed in women. CRF was inversely associated with mortality in men and women, and the associations remained significant after further adjustment for PA. In the PA and CRF combined analysis, compared with the reference group “not meeting the recommended PA (<500 metabolic equivalent-minute/week) and unfit”, the relative risks (95% CIs) of mortality were 0.62 (0.54 to 0.72) and 0.61 (0.44 to 0.86) in men and women “not meeting the recommended PA and fit”, 0.96 (0.61 to 1.53) and 0.93 (0.33 to 2.58) in men and women “meeting the recommended PA and unfit” and 0.60 (0.51 to 0.70) and 0.56 (0.37 to 0.85) in men and women “meeting the recommended PA and fit”, respectively.

Conclusions

CRF was more strongly associated with all-cause mortality than PA; therefore, improving CRF should be encouraged in unfit individuals to reduce risk of mortality and considered in the development of future PA guidelines.
Is daily walking when living in the Paralympic village different to the typical home environment?
Authors: Burkett Brendan
Published: April 2010

Background

Life within the Paralympic village is exciting, and the preparation for competition of upmost importance. Due to the shear geographic size of the Paralympic village and associated competition venues, the amount of incidental walking could be different to an athlete's home environment, and any extra walking could potentially diminish athletic performance.

Objectives

To quantify the change (if any) in the amount of daily walking an athlete does during a typical day at home, when compared with when they are preparing for competition and competing.

Methods

The total number of steps per day was quantified using calibrated pedometers for 31 participants in four environments: at home, within a home-based national training camp, while abroad for an international training camp and when in the Paralympic village.

Results

There was a significant change in the daily step count with an average increase of 947 steps (or 13%) while in the national training camp, an increase of 3488 steps (or 53%) when in the international camp and an increase of 5472 steps (or 83%) when in the Paralympic village.

Conclusion

To enable the maximum possible sporting performance at the 2012 London Olympic and Paralympic Games and beyond, athletes should monitor their incidental walking and adjust levels of activity accordingly. The layout and design of the Olympic and Paralympic village should consider the significant increase in incidental walking and provide improved mechanisms to avoid this unwanted issue.
Validation of Walk Score for estimating access to walkable amenities
Authors: Carr Lucas J , Dunsiger Shira I , Marcus Bess H
Published: April 2010

Background

Proximity to walkable destinations or amenities is thought to influence physical activity behaviour. Previous efforts attempting to calculate neighbourhood walkability have relied on self-report or time-intensive and costly measures. Walk Score is a novel and publicly available website that estimates neighbourhood walkability based on proximity to 13 amenity categories (eg, grocery stores, coffee shops, restaurants, bars, movie theatres, schools, parks, libraries, book stores, fitness centres, drug stores, hardware stores, clothing/music stores).

Objective

The purpose of this study is to test the validity and reliability of Walk Score for estimating access to objectively measured walkable amenities.

Methods

Walk Scores of 379 residential/non-residential addresses in Rhode Island were manually calculated. Geographic information systems (GIS) was used to objectively measure 4194 walkable amenities in the 13 Walk Score categories. GIS data were aggregated from publicly available data sources. Sums of amenities within each category were matched to address data, and Pearson correlations were calculated between the category sums and address Walk Scores.

Results

Significant correlations were identified between Walk Score and all categories of aggregated walkable destinations within a 1-mile buffer of the 379 residential and non-residential addresses. Test–retest reliability correlation coefficients for a subsample of 100 addresses were 1.0.

Conclusion

These results support Walk Score as a reliable and valid measure of estimating access to walkable amenities. Walk Score may be a convenient and inexpensive option for researchers interested in exploring the relationship between access to walkable amenities and health behaviours such as physical activity.
Treatment of refractory anterior knee pain using botulinum toxin type A (Dysport) injection to the distal vastus lateralis muscle: a randomised placebo controlled crossover trial
Authors: Singer Barbara J , Silbert Peter L , Song Swithin , Dunne John W , Singer Kevin P
Published: April 2010

Objectives

This randomised controlled crossover trial examined the efficacy of botulinum toxin type A (BoNT-A) injection, plus an exercise programme, to remediate chronic anterior knee pain (AKP) associated with quadriceps muscle imbalance.

Methods

24 individuals with refractory AKP received either BoNT-A (500 U Dysport) or the same volume saline injection to the vastus lateralis (VL) muscle and performed home exercises focusing on re-training the vastus medialis (VM) muscle. All subjects were offered open-label injection at 12 weeks. Knee-related disability (anterior knee pain scale; AKPS) and activity-induced pain (10 cm visual analogue scale) at 12 weeks were the primary outcomes. Peak isometric extensor force was recorded and normalised VL:VM ratios were derived from simultaneous surface electromyography. Selfreported pain and disability measures were collected at six time points to a mean of 20±8 months.

Results

14 subjects received BoNT-A and 10 placebo injection. Improvement at 12 weeks was significantly greater for BoNT-A compared with placebo-injected subjects for the AKPS (p<0.03), pain on kneeling (p<0.004), squatting (p<0.02) and level walking (p<0.04). At week 12, five placebo subjects crossed over to open-label injection. At 24 weeks, 16 of 19 BoNT-A-injected and two of the remaining five placeboinjected subjects were either satisfied or very satisfied with treatment outcomes. Improvements were maintained in 11 of 14 BoNT-A-injected and two of five placebo subjects available at longer-term follow-up.

Conclusion

BoNT-A injection produced a greater reduction in pain and disability than placebo injection in carefully selected patients with chronic AKP related to quadriceps muscle imbalance.
Head and traumatic brain injuries among Australian children, July 2000–June 2006
Authors: Berry Jesia G , Jamieson Lisa M , Harrison James E
Published: April 2010

Objective

To describe the rates of hospitalisation for head and traumatic brain injury among Australian children aged 0–14 years.

Design

Descriptive analysis of the Australian Institute of Health and Welfare National Hospital Morbidity Database, using data for the period 1 July 2000 to 30 June 2006.

Results

The rate of hospitalisation for head injury was 395.9 per 100 000 (95% CI 393.4 to 398.4), with 47.6 per 100 000 (95% CI 46.7 to 48.5) being high-threat-to-life injuries. In multivariate analysis, those aged 0–4 years had 1.8 times the rate of head injury of 10–14-year-olds, while boys had 1.7 times the rate of girls. Children living in very remote and remote areas had a 1.3–1.5-fold greater rate of head injury, and a 1.6–1.8-fold greater rate of injuries that were high threat to life, than city-dwelling children. The rate of traumatic brain injury (TBI) was 91.1 per 100 000 (95% CI 89.9 to 92.3), with 34.7 per 100 000 (95% CI 33.9 to 35.4) being high-threat-to-life injuries. In multivariate analysis, children aged 0–4 years had 0.8 times the rate of 10–14-year-olds, and boys had 1.9 times the rate of girls. Children living in the very remote and remote areas had a 1.9–2.8-fold greater rate of TBI, and a 1.5–1.7-fold greater rate of injuries that were high threat to life, than city-dwelling children.

Conclusions

Children living remotely were disproportionately represented among those sustaining head injuries. Almost a quarter of head injuries were TBI.
Characteristics of non-fatal fall injuries in rural India
Authors: Dandona Rakhi , Kumar G Anil , Ivers Rebecca , Joshi Rohina , Neal Bruce , Dandona Lalit
Published: April 2010

Background

Little is known about the context, risk factors and severity of non-fatal fall-related injury in India.

Objective

To report these data for a rural population in the East and West Godavari districts of the Indian state of Andhra Pradesh.

Methods

In a cross-sectional population-based survey, 3686 participants aged ≥30 years (83.6% participation) selected by stratified random sampling were interviewed in 44 villages. Participants recalled injuries in the preceding 12 months that required them to stay away from their usual daily duties for at least 1 day irrespective of whether medical attention was sought for that injury.

Results

The annual incidence of non-fatal fall-related injury based on a 3-month recall period was 3.30% (95% CI 2.54% to 4.05%) and 9.22% (95% CI 7.74% to 10.69%) for men and women, respectively, with the incidence increasing with age. For the most recent non-fatal fall-related injury, the home was the most common place of injury for women, and the farm for men, with the former more likely to fall while climbing up/down (20.9%) compared with the latter (10.3%). Most falls were at the same level (71.7%) and slipping was the most common cause of fall (40%). Limbs (legs, 55%; hand/arm, 33.3%) were the most commonly injured body part. Fifty-six per cent reported seeking treatment outside home for injury, of whom 74.6% were women; and 8.4% reported being admitted to a hospital.

Conclusion

Falls are a significant public health problem facing women in rural India. Fall prevention strategies should be explored and implemented within the Indian context.
A history of bryology in the San Juan Islands, Washington State, USAThis paper is one of a selection of papers published as part of the special Schofield Gedenkschrift.
Authors: Harpel Judith A.
Published: April 2010

The bryological history of Washington State, USA, is scattered and not well organized. An overall study of the moss flora within the San Juan Islands led to extensive searches of the major regional herbaria and a review of the relevant literature. This paper provides the foundation for a complete bryophyte history and moss flora of the state and reports new records of three species, Drepanocladus crassicostatus Janssens, Orthotrichum hallii Sull. & Lesq. in Sull., and Syntrichia papillosa (Wilson) Jur., and one variety, Syntrichia laevipila Brid. var. meridionalis (Schimp.) Wijk & Marg., for Washington.
Vegetation of eastern Unalaska Island, Aleutian Islands, AlaskaThis paper is one of a selection of papers published as part of the special Schofield Gedenkschrift.
Authors: Talbot Stephen S. , Schofield Wilfred B. , Talbot Sandra L. , Daniëls Fred J.A.
Published: April 2010

Plant communities of Unalaska Island in the eastern Aleutian Islands of western Alaska, and their relationship to environmental variables, were studied using a combined Braun-Blanquet and multivariate approach. Seventy relevés represented the range of structural and compositional variation in the matrix of vegetation and landform zonation. Eleven major community types were distinguished within six physiognomic–ecological groups: I. Dry coastal meadows: Honckenya peploides beach meadow, Leymus mollis dune meadow. II. Mesic meadows: Athyrium filix-femina – Aconitum maximum meadow, Athyrium filix-femina – Calamagrostis nutkaensis meadow, Erigeron peregrinus – Thelypteris quelpaertensis meadow. III. Wet snowbed meadow: Carex nigricans snowbed meadow. IV. Heath: Linnaea borealis – Empetrum nigrum heath, Phyllodoce aleutica heath, Vaccinium uliginosum – Thamnolia vermicularis fellfield. V. Mire: Carex pluriflora – Plantago macrocarpa mire. VI. Deciduous shrub thicket: Salix barclayi – Athyrium filix-femina thicket. These were interpreted as a complex gradient primarily influenced by soil moisture, elevation, and pH. Phytogeographical and syntaxonomical analysis of the plant communities indicated that the dry coastal meadows, most of the heaths, and the mire vegetation belonged, respectively, to the widespread classes Honckenyo–Elymetea, Loiseleurio–Vaccinietea, and Scheuchzerio–Caricetea, characterized by their circumpolar and widespread species. Amphi-Beringian species were likely diagnostic of amphi-Beringian syntaxa, many of these yet to be described.
Octoblepharum arthrocormoides (Calymperaceae) N. Salazar Allen & B.C. Tan, sp. nov., a new species from Tropical AsiaThis paper is one of a selection of papers published as part of the special Schofield Gedenkschrift.
Authors: Salazar Allen N. , Tan B. C.
Published: April 2010

A new species, Octoblepharum arthrocormoides Salazar Allen & B.C. Tan, is described from tropical Asia. In its erect, stiff and fragile leaves, the new species resembles Arthrocormus in physical appearance but differs from all other Asiatic Octoblepharum species. The new species shares features with the neotropical species, O. ampullaceum, having similar fragile leaves, but the later species has slightly thinner leaves (3–4 layers of hyalocysts above and below the chlorocysts layer) and pores of laminar hyalocists are bigger (4.88–7.32 µm), unlike the new species.
ARE THERE ANY NEW VACUA OF GAUGED ${\mathcal N}=8$ SUPERGRAVITY IN FOUR DIMENSIONS?
Authors: AHN CHANGHYUN , WOO KYUNGSUNG
Published: April 2010

We consider the most general SU(3) singlet space of gauged [Formula: see text] supergravity in four dimensions. The SU(3)-invariant six scalar fields in the theory can be viewed in terms of six real four-forms. By exponentiating these four-forms, we eventually obtain the new scalar potential. For the two extreme limits, we reproduce the previous results found by Warner in 1983. In particular, for the [Formula: see text] critical point, we find the constraint surface parametrized by three scalar fields on which the cosmological constant has the same value. We obtain the BPS domain-wall solutions for restricted scalar submanifold. We also describe the three-dimensional mass-deformed superconformal Chern–Simons matter theory dual to the above supersymmetric flows in four dimensions.
ON QUANTUM SPECIAL KÄHLER GEOMETRY
Authors: BELLUCCI STEFANO , MARRANI ALESSIO , ROYCHOWDHURY RAJU
Published: April 2010

We compute the effective black hole potential V BH of the most general [Formula: see text], d = 4 (local) special Kähler geometry with quantum perturbative corrections, consistent with axion-shift Peccei–Quinn symmetry and with cubic leading order behavior. We determine the charge configurations supporting axion-free attractors, and explain the differences among various configurations in relations to the presence of "flat" directions of V BH at its critical points. Furthermore, we elucidate the role of the sectional curvature at the nonsupersymmetric critical points of V BH , and compute the Riemann tensor (and related quantities), as well as the so-called E-tensor. The latter expresses the nonsymmetricity of the considered quantum perturbative special Kähler geometry.
AN IMPROVED HOUGH TRANSFORM ALGORITHM FOR RADAR DETECTION
Authors: ZENG J. , ZHANG J. , XIANG L. , DONG Z. , YUAN S.
Published: April 2010

In this paper, we describe a new algorithm for radar detection based on the Hough transform which employs the slope-intercept parameter space. Unlike the conventional Hough transform, we shift the parameter space cells to perform the transform. The computation burden is reduced. Another advantage is that those straight lines whose intercept are bigger than the radar maximum range can also be detected. In addition, we also investigate the performance of the algorithm we present and show its efficiency with some simulations.
EMBEDDED CONTROLLED PULSE CONVERTER FED INDUCTION HEATER
Authors: KIRUBAKARAN D. , RAMA REDDY S.
Published: April 2010

A pulse-current converter topology for induction heating is simulated and implemented. The possibility and expediency of the pulse current for induction heating have been demonstrated. The converter comprises the input filter, input reactor, bridge rectifier, two power switches, two coils mutually coupled with the input reactor and the heating inductor (load), where the output power is controlled by a switching frequency. The steady-state analysis of the converter operation and its computer simulation has been performed. The simulation on the computer are shown to be in good agreement with the theoretical results. The following two goals have been achieved: (a) the analysis of the heating process with the pulse current has been performed; and (b) the appropriate scheme of the pulse-current supply has been developed. The scheme fulfills the requirements of modern power supplies: sine form of the input current, unity power factor, soft commutation and a wide range of output power. This configuration can be used for heating, annealing, melting and hardening in the power range of 250–300 kW.
SELECTIVE HARMONIC ELIMINATION NON-SYMMETRICAL BIPOLAR PULSE WIDTH MODULATION TECHNIQUE: ANALYSIS AND EXPERIMENTAL VERIFICATION
Authors: DAHIDAH MOHAMED S. A.
Published: April 2010

Selective harmonic elimination pulse width modulation (SHE-PWM) techniques offer a tight control of the harmonic spectrum of a given voltage waveform generated by a power electronic converter along with a low number of switching transitions. These optimal switching transitions can be calculated through Fourier theory, and for a number of years quarter-wave and half-wave symmetries have been assumed when formulating the problem. It is shown recently that symmetry requirements can be relaxed as a constraint. This changes the way the problem is formulated and different solutions can be found without a compromise. This paper reports solutions to the switching transitions of a bipolar SHE-PWM when both the quarter- and half-wave symmetries are abolished. Selected simulation and experimental results are reported to show the effectiveness of the proposed method.
AN UNUSUAL 3D AUTONOMOUS QUADRATIC CHAOTIC SYSTEM WITH TWO STABLE NODE-FOCI
Authors: YANG QIGUI , WEI ZHOUCHAO , CHEN GUANRONG
Published: April 2010

This paper reports the finding of an unusual three-dimensional autonomous quadratic Lorenz-like chaotic system which, surprisingly, has two stable node-type of foci as its only equilibria. The new system contains the diffusionless Lorenz system and the Burke–Shaw system, and some others, as special cases. The algebraic form of the new chaotic system is similar to the other Lorenz-type systems, but they are topologically nonequivalent. To further analyze the new system, some dynamical behaviors such as Hopf bifurcation and singularly degenerate heteroclinic and homoclinic orbits, are rigorously proved with simulation verification. Moreover, it is proved that the new system with some specified parameter values has Silnikov-type homoclinic and heteroclinic chaos.
BIFURCATIONS AND CHAOS IN FRACTIONAL-ORDER SIMPLIFIED LORENZ SYSTEM
Authors: SUN KEHUI , WANG XIA , SPROTT J. C.
Published: April 2010

The dynamics of fractional-order systems have attracted increasing attention in recent years. In this paper, we numerically study the bifurcations and chaotic behaviors in the fractional-order simplified Lorenz system using the time-domain scheme. Chaos does exist in this system for a wide range of fractional orders, both less than and greater than three. Complex dynamics with interesting characteristics are presented by means of phase portraits, bifurcation diagrams and the largest Lyapunov exponent. Both the system parameter and the fractional order can be taken as bifurcation parameters, and the range of existing chaos is different for different parameters. The lowest order we found for this system to yield chaos is 2.62.
MULTISCALE BIOLOGICAL TISSUE MODELS AND FLUX-LIMITED CHEMOTAXIS FOR MULTICELLULAR GROWING SYSTEMS
Authors: BELLOMO NICOLA , BELLOUQUID ABDELGHANI , NIETO JUAN , SOLER JUAN
Published: April 2010

This paper deals with the derivation of macroscopic tissue models from the underlying description delivered by a class of equations that models binary mixtures of multicellular systems by methods of the kinetic theory for active particles. Cellular interactions generate both modification of the biological functions and proliferative and destructive events. The asymptotic analysis deals with suitable parabolic and hyperbolic limits, and is specifically focused on the modeling of the chemotaxis phenomena.
The Lower Cretaceous chalk play in the Danish Central Trough
Authors: INESON J. R.
Published: April 2010

The Upper Hauterivian to Lower Albian strata of the Danish Central Trough comprise a varied succession of pelagic coccolith chalks, argillaceous chalks and marlstones with subordinate claystones. Where well developed, such as in the recently released North Jens-1 well, the reservoir-quality chalks form three distinct packets, separated by marlstone-dominated intervals. The latter include the dark, organic-rich markers, the Munk Marl Bed (Middle Barremian) and the Fischschiefer Member (Lower Aptian), which are widely recognized in NW Europe. The internal construction of the chalk play is also strongly influenced by unconformities, often of regional significance, which commonly define the boundaries of the individual chalk packets. Lateral variation in the stratigraphic development of these unconformities results in local truncation or absence of individual chalk units. Preliminary sequence stratigraphic analysis suggests that the stratigraphic development of the Lower Cretaceous chalk play in the Danish Central Trough resulted primarily from sea-level changes, although climatic changes during Barremian and Aptian times may have influenced carbonate production and siliciclastic supply. Gross thickness distribution patterns were controlled by local variation in subsidence and active inversion tectonism.
Genetic sequence stratigraphy for the North Sea Late Jurassic and Early Cretaceous: distribution and prediction of Kimmeridgian–Late Ryazanian reservoirs in the North Sea and adjacent areas
Authors: PARTINGTON M. A. , MITCHENER B. C. , MILTON N. J. , FRASER A. J.
Published: April 2010

Sediments of Kimmeridgian to Late Ryazanian age form a group of key hydrocarbon play fairways in the syn-rift Jurassic of the North Sea. The perceived yet-to-find reserves of these often subtle plays, lying at or below seismic resolution, have attracted considerable industry attention over the past few years. Reserves are currently estimated by BP Exploration at 1 to 5 billion barrels of oil equivalent, reservoired in three play systems: (1) apron fans (e.g. Brae type); (2) basin floor fans (e.g. Miller, Galley, Ettrick and Magnus types); (3) shallow marine shelf (e.g. Ula, Gyda, Fulmar, Piper, Clyde types).

In order to assess the future exploration potential of this play fairway, a high resolution, predictive, sequence stratigraphy was erected for the North Sea Late Jurassic. The stratigraphic framework combines data from over 500 exploration wells with seismic and field data (Magnus, Brae, Miller, Ula, Gyda and Clyde).

In the Late Oxfordian to Late Ryazanian, a total of 11 genetic stratigraphic sequences have been defined. They are bounded by maximum flooding surfaces which, within the limits of the biostratigraphy, represent basin-wide isochronous events across NW Europe and can be recognized in exploration wells and at outcrop from Greenland to the Wessex Basin. The maximum flooding surfaces have been biostratigraphically calibrated to provide a consistent and easily identifiable stratigraphic framework. Candidate sequence boundaries have been interpreted within this stratigraphic framework, from basin-ward shifts of facies belts, using sedimentological and wireline log data. The combination of these stratigraphic methods has produced a very powerful tool to predict the presence and distribution of potential reservoirs and play types across the entire North Sea Basin from outcrop in East Greenland to the offshore Netherlands.

The model suggests that three major cycles of sand input into the basin can be recognized with an overall marked decrease in net sand content with time. Each cycle is bounded by tectonically enhanced maximum flooding surfaces representing major periods of basin floor reorganization. The intervening maximum flooding surfaces temporarily switch off sediment supply to the basin but do not offset depocentres. These events can form important, field-wide permeability barriers.

It is proposed that the tectonically enhanced maximum flooding surfaces are a response to tectonic subsidence during maximum relative sea-level rise, whereas maximum clastic progradation occurs from basin margin uplift during relative sea-level fall. The model is considered to have application at regional and field-specific scales; for example, prediction of both basin floor fan distribution and potential intra-reservoir permeability barriers.
The interaction of structure and sedimentary process controlling deposition of the Upper Jurassic Brae Formation Conglomerate, Block 16/17, North Sea
Authors: CHERRY S. T. J.
Published: April 2010

Block 16/17 is located in the UK Sector of the South Viking Graben adjacent to the Fladen Ground Spur. The block has yielded four major oil fields to date, and the principal reservoir is the Upper Jurassic Brae Formation.

Relative uplift of the basin margin associated with the onset of a major extensional phase during the Oxfordian, and related seismic activity, generated gravity and turbidity flows which deposited coarse submarine conglomerates at the base of the graben boundary fault scarp.

The distribution of these deposits has been controlled in part by the presence of transfer faults which cross-cut the graben boundary fault system. Transfer faults reflect the older structural grain of the area, which was mainly Caledonide and Tornquist. Detailed interpretation of a 3D seismic dataset has identified locations for possible submarine fan feeder channels. These are interpreted to be ‘canyon-like’ features located high on the terrace and closely controlled by major transfer faults. Such structural channelling has produced ‘shadow zones’, which are areas relatively starved of coarse clastic input in the basin.

The geometry of the graben boundary footwall varies along-strike, and has influenced the lithofacies associations within the Brae Formation.
Evolving depositional geometries in the North Sea Jurassic rift
Authors: MILTON N. J.
Published: April 2010

The tectonic history of the North Sea during the Middle and Upper Jurassic consists of initial basin-scale uplift, followed by subsidence. The subsidence is at least partly associated with a major rifting episode culminating in the Early–Mid-Kimmeridgian. Shallow marine depositional cycles of progradation and retrogradation are recognized throughout this time interval, with a periodicity of 1–5 million years.

Twelve of these units, selected from data-constrained study areas, are described, and quantified data are presented on their geometry, duration, and the implied variations in accommodation volume.

Sediment input rates into the basin decreased through the Middle and Upper Jurassic as hinterlands were drowned, and source/basin relief decreased. A corresponding evolution in the geometry of the units is seen, from wide tabular units in the Bajocian/Bathonian to narrow ribbon-geometry units in the Kimmeridgian.

The continued decrease in sediment input resulted in an interval of basin-wide marine condensation. On seismic data this forms a prominent surface of marine onlap known as the Base Cretaceous (or Late Cimmerian) ‘Unconformity’.

This pattern of decreasing depositional dimensions of shelf/shoreline systems is to be expected in marine rifts without access to continental drainage systems, where sediment supply decreases with syn-rift and post-rift subsidence of drainage basins. This decrease may happen throughout the late pre-rift to early post-rift, and the change from structure-independent to structure-dependent facies trends may not occur suddenly at the onset of rifting.
Structural controls on the Late Jurassic age shelf system, Ula Trend, Norwegian North Sea
Authors: STEWART I. J.
Published: April 2010

The Ula Trend of the Norwegian North Sea is an important producing area sited on the eastern margin of the Central Trough. Two fields, Ula and Gyda (combined reserves of 635 MMBBL), are on stream, and several other petroleum pools have been discovered. They key to success in the area is to predict the presence of Kimmeridgian to Portlandian age shallow-marine shelf sandstone reservoirs. Well and seismic data have shown the reservoir sequences to have a complex distribution controlled largely by the structural topography at the time of deposition. Structural interpretation of the 3D seismic datasets over the Ula and Gyda field areas and dense 2D data over the Ula Trend as a whole have revealed new insights into the geometry of the Jurassic rift margin. A relationship has been established between the Jurassic faults and the underlying salt wall topography to a deeper Early Permian age extensional system. During Late Jurassic extension, the deeper faults cut up-section and involved the Upper Permian, Triassic and Jurassic cover. Original Early Permian dip-slip faults maintained their sense of motion, while a linked oblique-slip set acted in sinistral transtension. The cover section accommodated, the differing styles with both simple extensional structures and more complex transtensional and contractional geometries, respectively. The structural pattern has been further complicated by episodic hangingwall inversion in Cretaceous and Tertiary times and the inversion geometries provide important petroleum traps (e.g. Ula Field). The Jurassic rift margin fault system and the geometry of its hangingwall governed the location of the Kimmeridgian shelf and shelf-break, as well as the entry and dispersal of sediment on the shelf. The structural interpretation has thus allowed a predictive model for shelf geometry and hence reservoir distribution to be established, and this forms the basis for continued exploration in this complex and increasingly mature play fairway.
Geology and hydrocarbon prospects of the Paleozoic in the Baltic region
Authors: BRANGULIS A. P. , KANEV S. V. , MARGULIS L. S. , POMERANTSEVA R. A.
Published: April 2010

Within the East Baltic region the main prospective area for hydrocarbons is the Peribaltic Depression (‘Baltic Syneclise’). Four sedimentary successions are developed, separated by major tectonic hiatuses. Total sedimentary thickness ranges from less than 1 km to over 8 km. Hydrocarbon occurrences are limited to the Paleozoic section where rich oil-prone source rocks are found. These contain TOC of 11–23% in the alum shale facies of the Cambrian, with 13% and 16% in the Ordovician and Silurian, respectively. Oil window maturity is reached on burial to 2000 m, with the main kitchen being in the Gdansk–Kura Depression.

Main reservoir development is within Middle Cambrian sandstones, where porosities of 20–30% and permeabilities of a few Darcies are preserved. Fields are combined structural/stratigraphic traps associated with fold noses and fault blocks providing structural closure. Ordovician and Silurian carbonates contain abundant shows, with current limited production from the Swedish island of Gotland. These traps are associated with algal mudmounds draped by organic-rich clays.

Most new prospects have been identified in the offshore Baltic Basin, where 35 wells have been drilled, resulting in the discovery of eight oil and gas fields, one of which is the largest found to date in the Baltic region.
The case for exploration of deep plays in the Variscan fold belt and its foreland
Authors: SMITH N. J. P.
Published: April 2010

The hydrocarbon prospectivity of Paleozoic rocks in the Northern Variscide Chain and its foreland has been examined. A model of the Variscides involving an opening and closing Rheic Ocean is preferred to existing models. Seismic reflection profiles are interpreted as evidence for early Paleozoic extension, which led to the formation of the ocean. In addition to prospects in late Paleozoic rocks, the early Paleozoic rocks, near the Variscan Front and on the foreland, should be targets for exploration. Along strike within the external zones, differences in Westphalian coal maturity indicate higher geothermal gradients, rather than burial effects. Carboniferous rocks reside in both oil and gas windows, north of the Variscan Front. A low maturity area coincides with Variscan uplift of the Worcester and Usk highs. Potential reservoir, source and sealing rocks have been removed from a large part of this structure. Adjacent basins, therefore, offer the best prospects.

Untested Silurian shales, beneath thick Devonian sediments, may lie in the oil window. Prospects and leads are indicated on several British Geological Survey and commercial seismic profiles. The foreland area of St George’s Channel–Cardigan Bay basins includes definite Carboniferous rocks. Coals are probably present, combined with Triassic reservoirs, salt seal and basin margin structures. A depth-maturity profile is required before prospectivity can be compared to other productive deep basins. The internide zones of the Variscides are generally overmature, and reached optimum maturity earlier than the externides. Nevertheless, overlying limnic coal basins are prospective, and can be expected within the Saxo-Thuringian zone (offshore UK only). Thin-skinned tectonics and sub-thrust plays are probably restricted to SW Wales and east of Kent. Hydrocarbons are produced, from early Paleozoic rocks in deep basins, on all the other plates (forelands) surrounding the former Paleozoic oceans.
Permo-Carboniferous plays of the Silver Pit Basin
Authors: BAILEY J. B. , ARBIN P. , DAFFINOTI O. , GIBSON P. , RITCHIE J. S.
Published: April 2010

The Silver Pit Basin is situated in the northern part of the southern Gas Basin, and is separated from the Sole Pit Basin to the south by the Outer Silver Pit Fault. Over much of the basin up to 400 m of Silverpit Formation interbedded shales and evaporites are present. The absence of the Leman Sandstone reservoir over much of the basin has meant that gas discoveries predominate in the Carboniferous (e.g. Caister, Murdoch) rather than in the Permian, as in the Sole Pit Basin.

In the Silver Pit Basin and its immediate margins, hydrocarbons have been discovered in Paleozoic reservoirs ranging from Dinantian sandstones to Zechstein carbonates. Within the Carboniferous the most significant reservoirs are fluvio-deltaic sandstones within the Westphalian and Upper Namurian. The best quality reservoirs are generally found in the coarsest sandstones, though locally the development of fracture porosity and secondary porosity due to leaching can be significant.

The reservoir potential of the Permian is only significant around the margins of the Silver Pit Basin. On the southern margin, at the feather edge of the main Rotliegend Leman Sandstone fairway, significant gas accumulations are present in aeolian and mixed aeolian/sabkha facies. On the northern margins the presence of Zechstein intra-basinal highs resulted in the local deposition of carbonates which may also have reservoir potential.

The main source rocks are coals and shales within the Carboniferous, predominantly in the Westphalian, but also to a lesser extent in the Namurian and Dinantian. The main kitchen area is in Quadrant 44, where significant gas generation has occurred since the Cretaceous. Migration and hydrocarbon charging is relatively straightforward for the Leman Sandstone and Carboniferous sandstone reservoirs. For Zechstein carbonate reservoirs migration via basin margin faults facilitates hydrocarbon charging.

The most significant regional seal is provided by the Permian sequence of Silverpit shales and overlying Zechstein evaporites. Carboniferous shales probably also act as seals on a local or semi-regional scale, supplementing the regional seal and contributing to deep intra-Carboniferous traps. Most discoveries have been made in reservoirs immediately beneath the Base Permian Unconformity and generally the prospective areas are best identified by mapping at Base Zechstein/Base Permian horizons.

The most prospective structures are associated with the major northwest-southeast-trending structural highs, often as ‘pop-up’ features. Most accumulations are predominantly structurally closed; however, for the ‘feather-edge’ Rotliegend play, closure to the northwest can have a stratigraphic component.
The Rotliegend in northwest Germany, from frontier to fairway
Authors: BURRI P. , FAUPEL J. , KOOPMANN B.
Published: April 2010

In northwest Germany most of the Rotliegend gas fields are confined to an approximately 50 km wide belt, a fairway, which stretches from Groningen in the west to Salzwedel–Peckensen in the east. About 400 × 10
9
m
3
of raw gas have been discovered in more than 40 separate gas accumulations which are contained in both structural and combined structural-stratigraphic traps at depths of 3.5 to 5 km. Reservoir facies and diagenesis are the main limiting factors in the play. Mapping of seismic attributes and their calibration to sedimentary facies and diagenesis are required to identify the ‘sweet spots’ of producible reservoir on the flanks of palaeo-highs or in Rotliegend grabens. Technological advances and improved geological concepts have led to repeated revivals of exploration activity and enhanced discovery rates. The latest impetus came with the application of 3D seismic.
The Caister Fields, Block 44/23a, UK North Sea
Authors: RITCHIE J. S. , PRATSIDES P.
Published: April 2010

The Caister Gas Fields are located in Block 44/23a, within the Silver Pit Basin area of the Southern North Sea Basin and comprise a Bunter accumulation overlying a Carboniferous accumulation. The Carboniferous structure is a faulted northwest–southeast-trending anticline, bounded to the northeast by a major reverse fault. The reservoir is formed of early Westphalian B braided channel sandstones, the thickness of which varies from 20–50 m over the field. Porosity is fair with an average of 11%. Average horizontal permeability is 5 mD, although permeabilities up to 400 mD are measured. The Bunter structure is a simple, unfaulted, elongate northwest–southeast-trending dome, with seal provided by the overlying Haisborough Group saliferous shales. The sheet-flood reservoir sandstones, with a thickness of 150 m over the field, have an average porosity of 21% and an average horizontal permeability of 100 mD. Combined initial gas in place is estimated at approximately 400 BCF with recoverable reserves in the order of 300 BCF.
Tectonic and stratigraphic aspects of the East Irish Sea Basin and adjacent areas: contrasts in their post-Carboniferous structural styles
Authors: JACKSON D. I. , MULHOLLAND P.
Published: April 2010

A revised geological map and lithostratigraphic correlation chart are presented for Carboniferous–Lower Jurassic strata in the East Irish Sea Basin (EISB) and contiguous basins of the NW–SE- to NNW–SSE-trending Clyde Belt. The significance of the exceptionally thick Triassic succession (4375 m) is documented in relation to other Triassic rifts of NW Europe. Basin margin faults within the Clyde Belt are basement-controlled and located either along the margins of exposed and concealed Ordovician–early Devonian buoyant granites, or orthogonal to earlier Paleozoic structures.

Four basic and markedly different structural styles have been identified from seismic interpretation. The styles comprise: solitary Caledonoid-trending folds (typically elongate centroclines) with minimal NW–SE faulting (style 1); synthetic and antithetic fault systems in single NW–SE half-graben on the fringes of the Clyde Belt (style 2); linked half-graben with large tilted fault blocks and stacked Permo-Triassic halite detachments in the centre and north of the EISB (style 3); and small step-faulted tilt blocks without thick Permo-Triassic halites, but again forming linked half-graben, in the south and on the fringes of the EISB (style 4). The styles are largely independent of the age of the basin-fill, except style 3 which is restricted to Permian–Lower Jurassic successions.
Late Paleocene to Miocene compression in the Faeroe–Rockall area
Authors: BOLDREEL L. O. , ANDERSEN M. S.
Published: April 2010

Compressional structures are observed at several locations in the Faeroe–Rockall Area. One of these, the Wyville–Thomson Ridge Complex, is part of the Scotland–Greenland Ridge which forms a barrier to the south-flowing deep cold arctic water from the Norwegian Sea. Interpretation of seismic multichannel reflection profiles suggests that the Wyville–Thomson Ridge Complex is the result of compression and that the Ymir Ridge and the Wyville–Thomson Ridge are ramp anticlines connected with a fault plane dipping to the north. A number of small highs offset by reverse faults to the south of the complex are interpreted as foreland thrust folds developed in relation to the tectonic evolution of the ridge complex. At least three Eocene to Miocene compressional phases are recognized. The first took place in late Paleocene–early Eocene and the second in Oligocene times. These compressional phases coincide with pronounced changes in the sea floor spreading geometry in the NE Atlantic. The third phase, in the middle or late Miocene, may possibly be associated with the complex Miocene spreading history of Iceland.
Preliminary observations of Neogene–Quaternary depositional processes in the Faeroe–Shetland Channel revealed by high-resolution seismic facies analysis
Authors: DAMUTH J. E. , OLSON H. C.
Published: April 2010

The Neogene and Quaternary sediments of the Faeroe–Shetland Channel and West Shetland slope have been deposited and modified through the interaction of a variety of downslope and parallel-to-slope depositional processes. The upper slope is dominated by mass-transport deposits (debris flows) which progressively diminish downslope. These were apparently deposited during glacial cycles when ice sheets reached the shelf edge and supplied large amounts of terrigenous sediment to the slope. Thin, prograding clinoforms separate packages of debris flows and may represent glacial marine sedimentation during periods of ice retreat from the shelf edge (e.g. interstades). A few submarine canyons occur on the slope and probably provide conduits to the basin for turbidity currents and related mass flows. The middle to lower slope appears to be dominated by glacial marine, hemipelagic and possibly turbidity-current deposits, which have been subjected to reworking by contour currents at many locations. A thick deposit that has the appearance of a deep-sea fan occurs on the middle slope in the northeast part of the area. Although many individual seismic packages within this feature have the appearance of aggradational channel–levee systems, these packages may actually represent contourite deposits. Large migrating sediment waves occur just downslope from this feature and suggest that strong contour currents have interacted with the downslope processes to redistribute sediments on the lower slope. The basin floor has thin conformable sediments that appear to be predominantly glacial marine and hemipelagic with occasional turbidites and debris flows. Thick, extensive debris-flow deposits also occur beneath the basin floor in the northeastern part of the area. The Neogene–Quaternary sediments are separated from the Paleogene section by a major regional unconformity of latest Oligocene or early to middle Miocene age, which forms a major sequence boundary throughout the region.
Structural models for the evolution of the North Sea area
Authors: WILLIAMS G. D.
Published: April 2010

During the past decade, numerous theories on the geometry and kinematic evolution of fault systems have been expounded. Listric normal faults with shallow detachments generate roll-over anticlines. Alternatively, planar faults bounding rigid blocks, the ‘domino’ model, may be more realistic in many areas of the North Sea. From onshore analogues, relay ramps connecting en échelon extensional faults are shown to be more common than transfer faults. Recent work on fault displacement gradients has generated realistic models involving planar faults with ‘soft linkages’ for fault systems. Inversion tectonics and halokinesis are commonly observed in the Southern and Central North Sea, and their effects are sometimes difficult to separate using seismic profiles. Scaled analogue models have provided graphic illustrations of the progressive development of structures. The construction of balanced cross-sections, increasingly used in North Sea interpretations, is a technique that may be used to test the various geometric models. Links between fault system geometries at upper crustal levels and deeper crustal processes have been established using field studies, notably in the Basin and Range Province, coupled with the interpretation of COCORP and BIRPS deep seismic reflection profiles. Geometric, thermal and flexural isostatic factors are used in sophisticated modelling of lithospheric processes in the North Sea. Structural styles vary in different regions of the North Sea due to the underlying basement grain and the presence or absence of Permian and Triassic evaporites.