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The results of a statistical study of oxygen ion outflow using Cluster data obtained at high altitude above the polar cap is reported. Moment data for both hydrogen ions (H+) and oxygen ions (O+) from 3 years (2001-2003) of spring orbits (January to May) have been used. The altitudes covered were mainly in the range 5–12 RE geocentric distance. It was found that O+ is significantly transversely energized at high altitudes, indicated both by high perpendicular temperatures for low magnetic field values as well as by a tendency towards higher perpendicular than parallel temperature distributions for the highest observed temperatures. The O+ parallel bulk velocity increases with altitude in particular for the lowest observed altitude intervals. O+ parallel bulk velocities in excess of 60 km s-1 were found mainly at higher altitudes corresponding to magnetic field strengths of less than 100 nT. For the highest observed parallel bulk velocities of O+ the thermal velocity exceeds the bulk velocity, indicating that the beam-like character of the distribution is lost. The parallel bulk velocity of the H+ and O+ was found to typically be close to the same throughout the observation interval when the H+ bulk velocity was calculated for all pitch-angles. When the H+ bulk velocity was calculated for upward moving particles only the H+ parallel bulk velocity was typically higher than that of O+. The parallel bulk velocity is close to the same for a wide range of relative abundance of the two ion species, including when the O+ ions dominates. The thermal velocity of O+ was always well below that of H+. Thus perpendicular energization that is more effective for O+ takes place, but this is not enough to explain the close to similar parallel velocities. Further parallel acceleration must occur. The results presented constrain the models of perpendicular heating and parallel acceleration. In particular centrifugal acceleration of the outflowing ions, which may provide the same parallel velocity increase to the two ion species and a two-stream interaction are discussed in the context of the measurements.

Oxygen ion outflow associated with the cusp and cleft give rise to persistent oxygen ion beams which can be observed over the polar cap. For high altitude spacecraft such as Cluster these beams are often observed for several hours on each occasion. This allows for a study of typical temporal structures on the time scale of minutes. We have used 3 years of data from spring, January to May of years 2001 to 2003, for a study of the oxygen number flux variation in the polar cap ion outflow. The source of these oxygen ion beams is the cusp and cleft, and variations in ionospheric upflow on time scales of around 8 min have been reported from ground based studies using incoherent scatter radar. Such upflows typically do not reach escape velocity, and further energization above the ionosphere is required for outflow to occur. Our study shows that a typical time scale between sudden number flux enhancements observed by Cluster in a geocentric distance range of 5 RE to 12 RE is 5 to 10 min. A superposed epoch study does not reveal any significant convection velocity or temperature changes around the flux enhancement events. Sudden temperature enhancements occur with a typical time interval of about 4 min, A superposed epoch study does not reveal any number flux enhancements associated with the temperature enhancements. The clear modulation of the high altitude number flux in a manner which resembles the modulation of the ionospheric upflow indicates that this is the main limiting factor determining the total outflow. The process behind transient upflow events in the ionosphere is therefore important for the total ionospheric outflow. Subsequent heating above the ionosphere appears to be common enough in the cusp/cleft region that it does not significantly modulate the oxygen ion number flux.

Background Coral reefs are colored by eukaryotic chromoproteins (CPs) that are homologous to green fluorescent protein. CPs differ from fluorescent proteins (FPs) by intensely absorbing visible light to give strong colors in ambient light. This endows CPs with certain advantages over FPs, such as instrument-free detection uncomplicated by ultra-violet light damage or background fluorescence, efficient Förster resonance energy transfer (FRET) quenching, and photoacoustic imaging. Thus, CPs have found utility as genetic markers and in teaching, and are attractive for potential cell biosensor applications in the field. Most near-term applications of CPs require expression in a different domain of life: bacteria. However, it is unclear which of the eukaryotic CP genes might be suitable and how best to assay them. Results Here, taking advantage of codon optimization programs in 12 cases, we engineered 14 CP sequences (meffRed, eforRed, asPink, spisPink, scOrange, fwYellow, amilGFP, amajLime, cjBlue, meffBlue, aeBlue, amilCP, tsPurple and gfasPurple) into a palette of Escherichia coli BioBrick plasmids. BioBricks comply with synthetic biology’s most widely used, simplified, cloning standard. Differences in color intensities, maturation times and fitness costs of expression were compared under the same conditions, and visible readout of gene expression was quantitated. A surprisingly large variation in cellular fitness costs was found, resulting in loss of color in some overnight liquid cultures of certain high-copy-plasmid-borne CPs, and cautioning the use of multiple CPs as markers in competition assays. We solved these two problems by integrating pairs of these genes into the chromosome and by engineering versions of the same CP with very different colors. Conclusion Availability of 14 engineered CP genes compared in E. coli, together with chromosomal mutants suitable for competition assays, should simplify and expand CP study and applications. There was no single plasmid-borne CP that combined all of the most desirable features of intense color, fast maturation and low fitness cost, so this study should help direct future engineering efforts. Electronic supplementary material The online version of this article (10.1186/s13036-018-0100-0) contains supplementary material, which is available to authorized users.

Background. We performed a review of published case studies of osteomyelitis associated with cat-scratch disease to consolidate existing information on clinical presentation, diagnostic tools, therapy, and outcome, as well as presenting a case of disseminated cat-scratch disease in a 12-year-old female with skull osteomyelitis and spleen involvement.Methods. A search for articles indexed in PubMed, Embase, and Google Scholar was performed with the search terms “Bartonella,” “bone,” “osteomyelitis,” “osteolytic,” and “cat-scratch disease” limited to the immunocompetent pediatric population and articles in English.Results. 51 cases were identified. The average age was 7.8 years with equal sex distribution. Fever (84.3%), often with a prolonged course (64.7%), and osteoarticular pain (88.2%) were the most common clinical findings. Lymphadenopathy was present in 64.7% of patients. Vertebral body was mainly involved (51.9%). MRI (50%) and bone scintigraphy (48.1%) were favored to confirm osteomyelitis, while serology was the preferred microbiological diagnostic. Various antibiotics were prescribed in combined or sequential regimens, with median duration of therapy of 23 days. About 12.5% of patients did not receive any treatment. Most patients had excellent prognosis; in particular, all patients not receiving any therapy showed complete recovery and no recurrence of symptoms.Conclusions.Bartonella henselaeshould be considered in differential diagnosis of localized lymphadentitis. Osteoarticular pain or limitation during cat-scratch disease in children should always be investigated for bone spreading. Owing to good prognosis, invasive procedures to obtain the bone material should be avoided. Serology is the gold standard diagnostic tool and MRI is the best radiographic technique to define bone and surrounding tissue involvement. Treatment represents a never-ending dilemma: surgical intervention or use of antibiotics is still controversial, and more studies are needed to define the best antimicrobial regimen.

Conditions similar to those observed in the solar wind interaction with Venus and Mars where there is a planetary atmosphere in the absence of a global intrinsic magnetic field may also be applicable to Pluto. With up to 24 μbars inferred for the Pluto atmosphere it is possible that the feeble solar photon radiation flux that reaches by its orbit, equivalent to ∼10 −3 that at Earth, is sufficient to produce an ionization component that can be eroded by the solar wind. In view of the reduced solar wind density (∼10 −3 with respect to that at 1 AU) that should be available by Pluto its total kinetic energy will be significantly smaller than that at Earth. However, the parameter values that are implied for the interaction process between the solar wind and the local upper ionosphere are sufficient to produce a plasma wake that should extend downstream from Pluto. In view of its low gravity force the plasma wake should have a wider cross-section than that in the Venus and Mars plasma environment. Since Pluto rotates with the axis tilted ∼30° away from the ecliptic plane the plasma wake will be influenced by a Magnus force that has a large component is the north–south solar polar direction. That force will be responsible for propelling the plasma wake with a component that can be directed away from that plane. It is estimated that transport of solar wind momentum to the upper Pluto’s ionosphere implies rotation periods smaller than that of the solid body, and thus large values of the Magnus force that can increase the orientation of the plasma wake away from the ecliptic plane.

Measurements conducted with the ASPERA-4 instrument and the magnetometer of the Venus Express spacecraft show that the dynamic pressure of planetary O+ ion fluxes measured in the Venus wake can be significantly larger than the local magnetic pressure and, as a result, those ions are not being driven by magnetic forces but by the kinetic energy of the solar wind. Beams of planetary O+ ions with those properties have been detected in several orbits of the Venus Express through the wake as the spacecraft traverses by the noon-midnight plane along its near polar trajectory. The momentum flux of the O+ ions leads to superalfvenic flow conditions. It is suggested that such O+ ion beams are produced in the vicinity of the magnetic polar regions of the Venus ionosphere where the solar wind erodes the local plasma leading to plasma channels that extend downstream from those regions.

The Norwegian Atlantic margin, although frequently described as passive, has seen several significant and highly variable deformation events prior to and after early Cenozoic break-up. This chronology is strongly exemplified in the northern Voring Basin, where deformation resulted in significant vertical motions, including deep erosion and sediment reworking. Post-break-up compressional deformation is well documented in the NE Atlantic margins, and is represented in the north Voring Basin by the Vema and Naglfar domes. A prominent Maastrichtian–Paleocene pre-break-up phase of compression inverted the northern prolongation of the latest Turonian Vigrid Syncline. This syncline was the fairway for the approximately 1 km-thick Santonian–Campanian Nise Formation sandstone, shed from NE Greenland and/or the western Barents Sea margin. The inversion focused on the Vigrid Syncline axis, forming an anticline here referred to as the Vema–Nyk Anticline. The anticline may have been a major trap but was breached by erosion prior to collapse due to Late Paleocene extension. The remnant eastern half of the anticline is the Nyk High. The associated flanking syncline, the Nagrind Syncline, also remains preserved. The collapsed side of the anticline is the Hel Graben, which itself was inverted in the Middle Miocene time forming the Naglfar and Vema domes. More speculatively, the development of the Vigrid Syncline and its bounding structural highs, the Gjallar Ridge and Utgard High, may also represent folds, marking the onset of compressional buckling in the mid-Norwegian–NE Greenland rift system. The repeated compressional deformation, as well as the extensional collapse, was focused on the area subjected to Early Cretaceous hyperextension. Compressional buckling under relatively low stress levels is proposed to have been due to significant lithosphere weakening caused by the hyperextension, whereby both high attenuation of the crystalline crust and serpentinization of the upper mantle contribute to the weakening. The Late Cenozoic compression post-dated the hyperextension by approximately 110 Ma, which suggests that the weakening is long-lived and that lithosphere has not been strengthened significantly through time.

The Early Eocene magma-rich northeast Atlantic rifted margins contain a large number of pre-breakup and post-breakup compressional structures, located in abandoned Early Cretaceous hyperextended basins with crustal stretching factors of 3–4 or more. The deformation both predates and postdates the magma-rich breakup. The hyperextended basins are often underlain by high-velocity lower crustal bodies, which we argue represent partially serpentinized upper mantle. Long-lived lithospheric weakening and proneness to deformation is proposed to relate to crustal hyperextension, probably enhanced by mantle hydration.

Anomalously high velocity and high density bodies have been detected in the lower crust on the mid-Norwegian margin. The lower crustal bodies (LCB) are pronounced on the More and Voring margins segments and have mainly been interpreted as either magmatic or high-grade metamorphic in origin. Evolutionary models of the whole margin are heavily affected by the interpretation of the LCB and so are estimates of vertical movements and thermal structure in the area. A 3D gravity and magnetic model of the mid-Norwegian margin was constructed to map the main geological features of the margin and acquire the distribution of the LCB. The model utilizes the most recent potential field compilations on the margin and is constrained by extensive reflection seismic data and published refraction profiles. Further constraints on the model were attained from studying the isostatic state of the lithosphere. We present a map showing the distribution of the different LCB and discuss the implications for the structural and thermal evolution of the margin. The properties of the LCB vary across the margin and at least three different processes may be responsible for their existence. The LCB is commonly interpreted as igneous rock either intruded into the lower crust or underplated beneath it. The distribution of the LCB along the Voring margin has an apparent correlation with the offshore prolongations of major onshore detachments stemming from Late Caledonian orogenic collapse. This may point towards some relation between the LCB and these old zones of weakness and that the LCB represents high-grade metamorphic rocks. Detailed modelling on the More margin shows a spatial link between parts of the LCB and extremely thin crustal thickness, suggesting a serpentinized exhumed mantle origin.

The Rosetta spacecraft flew by Mars at a distance of 260 km on 25 February 2007 during a gravity assist manoeuvre. During the closest approach (CA) the lander magnetometer ROMAP was switched on. The dataset taken during this swingby provides insight into the plasma environment around Mars: in addition to a pronounced bow shock crossing Rosetta recorded the signature of the pile up region of draped magnetic field. Also the Rosetta measurements showed signatures of crustal magnetic field anomalies which can be verified by results of a crustal magnetic field model. In order to understand the measured field morphology, multi-ion hybrid simulations were performed. Some of the input parameters for the simulations were obtained from Mars Express (MEX) data which were contemporaneously collected during the Rosetta swingby. These simulations reproduces ROMAP magnetic field measurements and show that the interplanetary magnetic field pointed northward during the encounter. A spectral analysis shows upstream waves ahead of the bow shock and indicates the presence of the magnetic pile-up boundary (MPB). The multi-ion model reproduces the ion fluxes measured by MEX/ASPERA-3 and is in agreement with the measurements to within one order of magnitude.

The mild compressional structures of Cenozoic age on the passive margins bordering Norway, the UK, the Faroes and Ireland have been the subject of much discussion in the literature. Nevertheless, their origin remains enigmatic. Candidate mechanisms must be able to explain the generation of sufficient stress to cause deformation, the episodic nature of the structures and why they developed where they did. We examine these mechanisms and conclude that multiple causes are probable, while favouring body force as potentially the most important agent. The geometry and setting of the structures are incompatible with gravitational sliding and toe- thrusting, probably the commonest 'compressive' structuring around the Atlantic margins. A passive mode of origin featuring drape or flank sedimentary loading probably emphasized some of the structures, but cannot be invoked as a primary mechanism. Likewise, reactivation of base- ment structure probably focused deformation but did not initiate it. Far-field orogenic stress from Alpine orogenic phases and from the West Spitsbergen- Eurekan folding and thrusting is also examined. This mechanism is attractive because of its potential to explain episodicity of the com- pressional structures. However, difficulties exist with stress transmission pathways from these fold belts, and the passive margin structures developed for much of their existence in the absence of any nearby contemporaneous orogeny. Breakup and plate spreading forces such as divergent asth- enosheric flow have potential to explain early post-breakup compressional structuring, for example on the UK -Faroes margin, but are unlikely to account for later (Neogene) deformation. Ridge push, generally thought to be the dominant body force acting on passive margins, can in some circumstances generate enough stress to cause mild deformation, but appears to have low potential to explain episodicity. It is proposed here that the primary agent generating the body force was development of the Iceland Insular Margin, the significant bathymetric-topographic high around Iceland. Circumstan- tially, in Miocene times, this development may also have coincided with the acme of the compressional structures. We show that, dependent on the degree of lithosphere-asthenosphere coupling, the Iceland Plateau may have generated enough horizontal stress to deform adjacent margins, and may explain the arcuate distribution of the compressional structures around Iceland. Assuming transmission of stress through the basement we argue that, through time, the structures will have developed preferentially where the basement is hotter, weaker and therefore more prone to shearing at the relatively low stress levels. This situation is most likely at the stretched and most thermally-blan- keted crust under the thickest parts of the young (Cretaceous-Cenozoic) basins. Although several elements of this model remain to be tested, it has the potential to provide a general explanation for passive margin compression at comparatively low stress levels and in the absence of nearby orogeny or gravitational sliding.

The general scientific objective of the ASPERA-3 experiment is to study the solar wind — atmosphere interaction and to characterize the plasma and neutral gas environment within the space near Mars through the use of energetic neutral atom (ENA) imaging and measuring local ion and electron plasma. The ASPERA-3 instrument comprises four sensors: two ENA sensors, one electron spectrometer, and one ion spectrometer. The Neutral Particle Imager (NPI) provides measurements of the integral ENA flux (0.1–60 keV) with no mass and energy resolution, but high angular resolution. The measurement principle is based on registering products (secondary ions, sputtered neutrals, reflected neutrals) of the ENA interaction with a graphite-coated surface. The Neutral Particle Detector (NPD) provides measurements of the ENA flux, resolving velocity (the hydrogen energy range is 0.1–10 keV) and mass (H and O) with a coarse angular resolution. The measurement principle is based on the surface reflection technique. The Electron Spectrometer (ELS) is a standard top-hat electrostatic analyzer in a very compact design which covers the energy range 0.01–20 keV. These three sensors are located on a scanning platform which provides scanning through 180° of rotation. The instrument also contains an ion mass analyzer (IMA). Mechanically IMA is a separate unit connected by a cable to the ASPERA-3 main unit. IMA provides ion measurements in the energy range 0.01–36 keV/charge for the main ion components H+, He++, He+, 0+, and the group of molecular ions 20–80 amu/q. ASPERA-3 also was its own DC/DC converters and digital processing unit (DPU).

The present-day topography/bathymetry of the Norwegian mainland and passive margin is a product of complex interactions between large-scale tectonomagmatic and climatic processes that can be traced back in time to the Late Silurian Caledonian Orogeny. The isostatic balance of the crust and lithosphere was clearly influenced by orogenic thickening during the Caledonian Orogeny, but was soon affected by post-orogenic collapse including overprinting of the mountain root, and was subsequently affected by a number of discrete extensional events eventually leading to continental break-up in Early Eocene time. In the mid-Jurassic the land areas experienced deep erosion in the warm and humid climate, forming a regional paleic surface. Rift episodes in the Late Jurassic and Early Cretaceous, with differential uplift along major fault zones, led to more pronounced topographic contrasts during the Cretaceous, and thick sequences of clastic sediments accumulated in the subsiding basins on the shelf. Following renewed extension in the Late Cretaceous, a new paleic surface developed in the Paleocene. Following break-up the margin has largely subsided thermally, but several Cenozoic shortening events have generated positive contraction structures. On the western side of the on-shore drainage divide, deeper erosion took place along pre-existing weakness zones, creating the template of the present day valleys and fjords. In the Neogene the mainland and large portions of the Barents Sea were uplifted. It appears that this uplift permitted ice caps to nucleate and accumulate during the Late Pliocene northern hemisphere climatic deterioration. The Late Pliocene to Pleistocene glacial erosion caused huge sediment aprons to be shed on to the Norwegian Sea and Barents Sea margins. Upon removal of the ice load the landmass adjusted isostatically, and this still continues today.

Compilation of new and vintage aeromagnetric data from the Norwegian and Greenland Seas of the NE Atlantic provides evidence for a different interpretation of several tectonic elements. The previously interpreted oceanic fracture zones (Gleipne, Surt, Bivrost, Jenegga and Vesteralen) do not exist; these were artefacts of poor navigation and wide line spacing of the vintage dataset. This reinterpretation impacts our understanding of the early spreading history of the North Atlantic, as the opening of the Norwegian–Greenland Sea between the Jan Mayen and Senja-Greenland fracture zones occurred along a stable axis without offsets of the oceanic spreading anomalies or jumps in spreading axis. These results contradict the hypothesis that a spatial relationship exists between transfer zones and fracture zones on the Lofoten margin, and on the NE Greenland margin to which they have been projected. Simplified palaeogeographic reconstruction of the aeromagnetic map to Anomaly 22 reveals that a c. 50 km wide magnetic anomaly cuts across spreading anomalies 24A, 24B and 23 from the Voring Marginal High on the Norwegian margin to Traill O on the East Greenland coast. The anomaly is interpreted to represent an igneous complex referred to as the Traill-Voring igneous complex (TVIC). The complex crosscuts anomaly 22 on the Greenland margin, suggesting that the igneous activity was active until c. 50 Ma and can be linked up with the NNE-trending initial magmatic lineament (IML) extending between Traill O and Kangerlussuaq. The IML has been suggested to relate to a failed attempt of direct linkage between the Reykjanes and Mohns Ridges. The magnetic response of the TVIC along the Voring margin has previously been interpreted as representing anomaly 24A and 24B. Such an interpretation required the erroneous introduction of an abandoned spreading ridge.

The high-density lower crustal body (LCB) on the mid-Norwegian margin is almost universally interpreted to represent magmatically underplated material, added to the crust during Early Tertiary opening of the NE Atlantic. The thickness of the LCB is uneven, and its distribution along the margin is sharply limited by margin-perpendicular lineaments. Three-dimensional density modelling constrained by petrophysical and seismic data was performed to investigate the expression of the various lineaments (Bivrost, Jan Mayen, Gleipne, etc.) in the crustal architecture, with and without the LCB. The Bivrost Lineament, separating the Voring and Lofoten margin segments, is clearly expressed and so is arguably a lineament in the SW Voring margin. Notably, most of the lineaments can be interpreted as offshore prolongations of major onshore detachments stemming from Late Caledonian orogenic collapse. An alternative interpretation of the LCB is thus that it represents high-grade metamorphic rocks, remnant from the Caledonian root. Determining the nature of the LCB has profound effects for the volume estimate of magmatic rocks in the North Atlantic Igneous Province, and consequently also for the degree of crustal thinning and heat flow.

During the last c. 2.7 My, large quantities of glacially derived material were transported westwards from the Norwegian mainland areas and inner shelf and deposited mainly as prograding sediment wedges into a basin of intermediate depth offshore Mid Norway. The deposits are more than 1000 m thick in extensive areas, and are defined as the Naust Formation. In the Haltenbanken–Traenabanken region, the shelf edge migrated 100–150 km westwards. The narrow More shelf was built out only in the order of 30–50 km, mainly due to a steeper pre-existing slope dipping towards a much deeper basin. In this area, the Holocene Storegga Slide, as well as older slides, displaced slope sediments towards the deeper part of the basin. In Early Naust time, the most extensive progradation occurred in the northern area, possibly due to the combined effect of land uplift and glaciations. The importance of glaciations for the progradation of the More shelf and areas farther south increased through the Pleistocene period. The Norwegian Channel Ice Stream became very important during the last three glaciations, and a thick succession of glacigenic debris flows was deposited on the North Sea Fan. More than 400 m of sediments accumulated during the Weichselian. All the last three glaciations supplied glacial debris beyond the shelf edge. The most extensive progradation in the north was in the Skjoldryggen region, particularly during the Elsterian glaciation. During ‘ice-free’ periods, hemipelagic and contouritic sediments were deposited on the slope. Such sediments are most common in the Storegga Slide area, where they hosted glide planes beneath the major slides.

Final break-up of Pangaea – opening of the NE Atlantic (NEA) and the Arctic Eurasia Basin – was associated with significant magmatism (in the NEA) and is commonly ascribed to thermal effects from a proto-Iceland plume. The plume is often assumed to be fixed with respect to the Earth’s core and to have governed NEA break-up. It is argued here that the Iceland anomaly, past and present, cannot represent a fixed plume, nor be rooted at the core–mantle boundary and that the Greenland–Faroes Ridge is inconsistent with a classic time-transgressive hotspot track. It is shown that the Iceland anomaly has probably been located at the constructive plate boundary (Mid-Atlantic Ridge and antecedents) since its inception. While recent studies allow for some ‘wandering’ of hotspots relative to the core and mantle, it is considered unlikely that such drift of a mantle plume would precisely match lithospheric drift in order to achieve constant centering on the spreading ridge. The alternative view is, therefore, supported – that the anomaly is an upper mantle response to plate break-up. The two pulses of NEA magmatism are related to separate phases of North Atlantic break-up. Early Paleocene magmatism ( c . 62–58 Ma) was governed by a short-lived attempt at seeking a new rift path, intermediate in time and space between the Labrador Sea–Baffin Bay and the NEA–Eurasia Basin rifts. The voluminous Early Eocene magmatism ( c . 56–53 Ma) along the NEA margins was related to final break-up of Pangaea, exploiting the collapsed Caledonian fold belt. The interpretations here are at odds with Iceland representing a classic Morgan-type plume and it is suggested that the magmatism in the NEA and the Iceland anomaly represent a ‘top-down’ effect of plate tectonics.

Since the initial breakup of the Norwegian–Greenland Sea in Early Eocene time (Chron 24B, 53.7 Ma), the conjugate ‘passive’ margins have been subject to compression, extension, magmatism, and broad uplifts and subsidence. Mid- to Late Cenozoic compressional doming basin inversion and reverse faulting occurred predominantly offshore within the rheologically weak deep Cretaceous depocenters. On the Norwegian margin, the domes seem to have formed primarily in Middle Eocene to Early Oligocene, and in Early Miocene, while doming in the Faroes–Rockall region developed in Late Paleocene to Early Eocene, Oligocene, and Mid- to Late Miocene. We suggest that the main driving force was plume-enhanced ridge push. A testable working hypothesis is that discrete phases of compression were associated with periods of high plume flux. In addition, the Oligocene (Chron 13, 35 Ma) change in plate motion appears to have generated local shear adjustments along pre-existing basement weaknesses, forming compressional structures in the overlying sedimentary section. This change in plate motion was first manifest by significant extension between the SW Barents Sea and the conjugate NNE Greenland margin, and led to spreading along the Knipovitch Ridge. Mid-Cenozoic extension and magmatism also preceded the development of the Kolbeinsey Ridge. The associated separation of the Jan Mayen microcontinent from East Greenland must have been strongly influenced by the position of the Iceland Plume center, in addition to the change in extension direction. With respect to initial breakup of the Norwegian–Greenland Sea in Early Eocene time, the mid-Cenozoic extension and magmatism is a post-breakup phenomena. Widely spaced areas of Neogene uplift occurred along all bordering margins. These enigmatic uplifted areas acted as nucleation sites for growth of ice caps, and initiated large glacial deposits that built out on the adjacent shelves.

A ponderomotive theory that describes the acceleration of magnetospheric ions along the geomagnetic field lines is developed and compared to Viking and Freja satellite observations showing that low-frequency electric field fluctuations correlate with the upward escape of ions. From the general expressions of the averaged field-aligned wave forces, we develop a theory for the nonresonance acceleration of the polar wind and resonant acceleration of a small admixture of heavy ions under the action of Alfven and ion cyclotron waves. Using a hydrodynamic polar wind model, we show analytically and numerically that the critical point of supersonic transition shifts toward the Earth under the ponderomotive action of the waves. Furthermore, the ion velocity, as well as the acceleration of the flow, increases as the wave amplitude increases. It is shown that the critical velocity always equals the local sound velocity, independent of whether Alfven waves are present or not. The asymptotic behavior of the flow (far above the critical point) is also modified substantially under the action of Alfven waves. In particular, the mere existence of waves in the flow causes an increasing upward acceleration with increasing distance from the Earth. We emphasize that the subsonic polar breeze is not subject to a qualitative modification under the action of Alfven waves, as opposed to the supersonic polar wind. In addition, we present a ponderomotive mechanism for the generation of field-aligned small-scale plasma density depletions which have been discovered by polar-orbiting satellites. The acceleration of heavy ions has been examined from the viewpoint of single-particle motion. The emphasis is on a phenomenon termed ponderomotive resonance. It is found that the energy gain of heavy ions increases as the first power of the wave amplitude provided the ion intersects the resonance region from the bottom upward, despite the fact that the ponderomotive force (“magnetic moment pumping”) is proportional to the second power of the wave amplitude. This leads to fast acceleration of heavy ions provided that high-amplitude waves propagate along geomagnetic field lines.

Gravity and magnetic field data covering mid-Norway and the Norwegian Sea were processed in order to enhance tectonic features on various scales. The local features were subjected to an unconventional processing technique involving a non-linear, adaptive Wallis filter designed to enhance the smallest wave lengths. When compared with recent structural information derived from seismic data, the processed gravity and magnetic maps show the main structural trends, major fault zones and basin boundaries, thus proving their worth for regional tectonic mapping. Previously undetected NW–SE-trending offshore crustal lineaments are revealed. A landward prolongation of the Bivrost Lineament appears to continue subparallel towards Proterozoic shear zones below the Caledonian nappes in the Rana area, either along the western margin of the Transscandinavian Granite–Porphyry Belt or the NW–SE-trending Mala–Skelleftea Tectonic Zone. A large lineament is also observed as a landward prolongation of the Surt Lineament indicating a relationship with the Storsjon–Edsbyn Deformation Zone, a major, deep, crustal shear zone in the Precambrian of Sweden. A slightly increased seismic activity, which is possibly related to the present ridge push force, is observed along parts of the previously unknown transfer zones. Combined gravity and magnetic modelling indicates a low crustal thickness in the northwesternmost part of the Voring Basin, between the Surt and the Jan Mayen Lineaments. The lack of correlation between the gravity and the magnetic patterns observed on the residual field maps suggests the presence of a shallow Curie isotherm situated above or within the uppermost basement.

The Atlantic margin of the Norwegian, Faeroese, British and Irish sectors encompasses numerous basins which vary in character, but are related in terms of their evolution as part of a single passive margin. Lineament analysis of the margin shows a predominance of NE–SW, N–S and NW–SE trends, mainly reflecting Mesozoic–Cenozoic extensional faulting. Some major Precambrian and Caledonian structures, principally steeply-dipping shears, were opportunistically reactivated according to the prevalent stress pattern. The extensional history of the margin spanned a c. 350 Ma interval between the close of the Caledonian orogeny and early Eocene break-up. Episodes of Permo-Triassic, (mainly late) Jurassic, Early Cretaceous, ‘middle’ Cretaceous and latest Cretaceous–Early Eocene age can be distinguished from one another in space and time. The anomalous length of the total period of extension prior to continental separation is partly explained by step-wise lateral offsets of the crustal thinning axes towards the line of eventual break-up. The picture is, however, complicated by some changes in extensional style and direction. These include mosaic-like fragmentation of Pangea in the Permo-Triassic, the imposition of more systematic E–W extension by Jurassic times, and the change to NW–SE extension focused on the present margin in the Early Cretaceous (probably Hauterivian). The resulting structural configuration reflects the overprinting of a complex network of Jurassic and older basins by a continuous NE–SW chain of deep Cretaceous-Cenozoic basins. An extensional pulse of latest Cretaceous to earliest Eocene age (best observed in the Norwegian Sea) with extensive basaltic volcanism led to continental break-up at approximately 53 Ma. The margin was structurally modified by some important events postdating the Early Eocene. On breakup, the background stress field changed from extension to mild SE-directed compression, and widespread inversion structures formed in the thick Cretaceous-Cenozoic depocentres. The inversions can best be explained by ridge-push from the adjacent spreading centres, but could also be linked to Tethyan closure events and changes in the North Atlantic spreading vector. Post-break-up extension of the North Atlantic passive margins has been reported in the western Barents Sea, Jan Mayen and East Greenland and (for the first time here) in the northern Voring Basin. We propose that these areas were linked by a single extensional pulse induced by the change to a more ESE-directed relative plate motion in the Oligocene-Miocene. Major uplift and exhumation of peripheral landmasses and inboard basins took place at intervals throughout the Cenozoic. Initial uplift can be attributed to pre-break-up rifting and post-break-up compression, but the most significant event took place in the Plio-Pleistocene and was intimately associated with glacial erosion and isostatic adjustment through repeated glaciations and interglacials. The regional scale of this event and its significance for exploration is widely under-estimated.

In this issue of Geology , [Tugend et al. (2015][1], p. 15) discuss rift geometries and hyperextension in the Bay of Biscay–Parentis (BBP) area. This is a well-defined propagating rift/ocean (e.g., [Sibuet et al., 2012][2]), with crustal architecture revealing a succession of zones typical of

The study takes in the entire NE Atlantic margin (NEAM) but emphasizes the sparsely drilled More and Voring Basins. A network of Permo-Triassic and Jurassic basins was strongly overprinted by younger extensional episodes. At least three phases are probable--early Cretaceous, mid-Cretaceous and latest Cretaceous-early Eocene--between the late Jurassic and break-up. Substantial thicknesses of Cretaceous and Cenozoic strata along the margin have focused exploration interest on the late Cretaceous and Paleocene intervals as easily drillable targets. Reservoirs within these intervals were deposited as gravity-driven sand incursions into an overwhelmingly mud-prone environment. Sand pulses of Albian-Coniacian, Santonian-early Campanian and Paleocene age occur widely, and can be tied to the tectonic episodes. Vertical migration of hydrocarbons from known Jurassic source rocks is proven west of Shetlands, but in many parts of the margin remigration from intermediate reservoirs would be required to charge the shallower plays. Failing this, prospectivity will hinge on the presence of frontier source rocks, with best possibilities at Barremian, Aptian-Albian, Cenomanian-Turonian and Paleocene levels. Potential hydrocarbon traps were formed by pre-breakup extensional faulting and by post-breakup compression.

A sub-regional tectonic study of the mid-Norwegian margin has been assimilated into a broader, regional study of the NE Atlantic margin. The NE Atlantic margin experienced several extensional events between Devonian post-orogenic collapse and break-up in Early Tertiary. This paper focuses on the extensional events between Early Cretaceous and Early Tertiary. It is suggested that NE-trending Early Cretaceous rifting followed the entire margin from the southern Rockall Trough to the Bjornoya Basin of the SW Barents Sea. This rift had a markedly different trend than the preceding N-trending Late Jurassic rift of, e.g., the North Sea. Seamounts may have been emplaced in the highly thinned basin axes during Early Cretaceous rifting. Subsequent rift events followed the Early Cretaceous rift trend. An enigmatic 9mid9-Cretaceous event, probably extensional, is observed in the northern part of the mid-Norwegian margin. The event is expressed by faulting in the inner Voring Basin, and by uplift of the outer Voring and Lofoten margins. Uplift is associated with a widespread unconformity. Uplift of the Gjallar Ridge in the Voring Basin culminated during the latest Cretaceous to Early Tertiary rifting, with structural geometries broadly similar to those seen in core complexes. A new tectonic model for NE Atlantic margin is proposed based on these observations, and builds on analogues from the modern rift system in the Red Sea and Woodlark Basin of Papua New Guinea.

The post-Cretaceous subsidence history of the Voring Basin, part of the Atlantic passive margin offshore mid-Norway, has been investigated. Extension and β -factors related to rifting and continental break-up during the Palaeocene have been quantified using both forward and reverse basin-modelling techniques. In the preferred geological model it is assumed that rifting occurred in the Voring Basin during the Palaeocene (prior to break-up), following an earlier rift event during the Late Jurassic. During Palaeocene rifting the basin may have been dynamically uplifted by the Iceland mantle plume. In the east of the basin there was no Palaeocene extension. Subsidence analysis shows that in the centre of the basin forward and reverse models converge to predict a modest Palaeocene stretching factor (β) of c. 1.15. In the west of the basin, closest to the Atlantic margin, forward models of upper-crustal faulting also predict a β of c. 1.15, but reverse (backstripped) models of subsidence predict a β of up to 1.75. We suggest that lower-crustal and mantle-lithosphere thinning close to the margin were greater than the extension accommodated by upper-crustal faulting and that some lower-crustal/mantle-lithosphere stretching associated with continental separation was partitioned below the Voring Basin, up to 150 km landwards of the margin.

A lineament pattern on the NE Atlantic margin is discussed, illustrated by gravity and magnetic images in the Norwegian Sea, and reviewed in the context of onshore field evidence. While most possible fault trends exist, three major sets predominate. A NE-SW left-stepping lineament set defines the gross geometry of the margin, while interposing northerly trends impose a rhomboidal geometry at a variety of scales. The margin is segmented by NW-SE transfer zones, sometimes involving significant offsets. The principal trends are primarily a function of Mesozoic-Cenozoic plate-wide extensional stress fields. Certain Proterozoic and Caledonian lineaments were, however, opportunistically reactivated according to the extension direction. Caledonian NE-SW orogen-oblique shears, typified by the More-Trondelag Fault Zone, were reactivated via (?Jurassic) strike-slip or oblique-slip, and were further exploited during Cretaceous-early Cenozoic extensional episodes leading to continental break-up. Jurassic E-W extension may also have reactivated N-S faults existing in the basement or generated in duplex systems between the NE-SW shears. Precambrian and Caledonian basement lineaments striking at a low angle to the extension direction probably predisposed the formation of major transfer zones.

We first briefly describe the wave-assisted cusp model according to which a standing compressional structure at the outermost portion of the high-altitude cusp produces the cusp precipitating particles from inflowing magnetosheath plasma. The model requires two realistic assumptions: (1) A direct inflow occurs in the high-altitude cusp from the magnetosheath to the plasma mantle, experiencing a change of the cross section (“Laval nozzle effect”). (2) A substantial amount of magnetospheric/ionospheric plasma is supplied to the plasma mantle (“mixture effect”). We next examine the model's predictions against the low-altitude observations. More than twenty observational cusp characteristics are well predicted by the model.

Compressional structures of Cenozoic age are ubiquitous features of the NE Atlantic margin between the western Barents Sea and offshore western Ireland. The structural suite includes simple domes or anticlines, reverse faults and broad-scale inversions. Our analysis focuses on a recently delineated group of structures in the Norwegian Sea, although these are placed in the context of similar features on the Barents margin, West of Shetlands, on the Faroes and their surrounding shelf, and in the Rockall Trough. Some (although not all) of the compressional anticlines were formed at the sites of pre-existing Cretaceous-Palaeocene depocentres. They show a multi-phase growth history. In the Norwegian Sea, particularly important phases occurred in the middle Eocene to early Oligocene and in the Miocene. We interpret the formation of these structures as a natural outcome of the transition to sea-floor spreading that occurred in the early Eocene. From this time, extremely thick sedimentary successions that had accumulated during some 300 million years of extensional tectonics were subjected to mild compression. The overall compressive stress field can be explained in terms of spreading in the adjacent ocean (ridge push) and by the distant effects of Alpine tectonics. In a plate-wide sense these effects can be regarded as two sides of the same coin. The origin of the Norwegian Sea structures is most easily visualized in terms of ridge push. NW-SE transfer zones, characteristic of the entire margin, are strongly implicated in these tectonics. A kinematic model is described that links significant structuring with a change in the spreading direction of Oligocene-Miocene age (35-20 Ma, A13-6). The compressional structures are mainly observed by their effect on sediments and volcanics of Cretaceous and Cenozoic age. They are frequently expressed in the present-day sea-floor relief, and in the case of the Faroe islands are probably responsible for present subaerial exposure. From the point of view of hydrocarbon exploration, the Cenozoic compressive anticlines have obvious potential as fourway dip closures or as components of structural-stratigraphic traps. The NW-SE fractures, orientated parallel or sub-parallel to the maximum horizontal stress direction, were probably periodically open for fluid flow from the time of NE Atlantic opening and onwards. They may therefore have facilitated migration from deeper source rocks or remigration from pre-existing hydrocarbon accumulations.

In vivo MR spectroscopy (MRS) requires some kind of volume selection method to be able to measure the signal from a selected part of the body. To be able to interpret the spectra correctly, the quality of the volume selection must be investigated for each new MRS application using phantom measurements. A new phantom, especially suitable for precision measurements of the volume selection performance, is presented. It contains a small, remotely controlled signal source placed inside a larger vessel. This principle can be applied to various body regions, coil types and nuclei. The measurement conditions are close to the clinical situation. The phantom does not have to be repositioned during a signal profile measurement and the signal contribution from each point along the profile is determined regarding sign and amplitude.

International operators are seeking, investigating and pursuing new business opportunities in the Arctic. While operating in the Arctic, there will be a considerable need for vessels to keep their position during various operations which may include lifting, installation, crew change, evacuation, and maybe drilling. Opposed to open water, the drifting ice poses severe limitations as to how stationkeeping operations may be carried out. Dynamic positioning systems are currently developed aiding stationkeeping without mooring systems. There is a considerable need to enhance the open water DP systems for use in a new forcing environment. Essentially a new technology has to be developed with time. For that reason, considerable knowledge is required concerning current limitations and boundary conditions. This paper addresses some of the generic challenges related to DP operations in ice together with relevant learnings which are employed in mentioned DP enhancements.Copyright © 2012 by ASME

According to present theoretical models, material ejected from the Martian satellite Phobos due to meteoroid bombardment and tidal coupling can stay for a long time in circular orbits near the planet, forming a dust belt. The dust particles are moving through various plasma domains of the Martian magnetosphere and may undergo electrostatic disruption there, producing very fine motes in the range 0.005-0.1 /spl mu/m which can stay positively charged for a time comparable with the orbital period. A negatively charged spacecraft will attract such particles and an ion spectrometer with wide enough mass range (1-10/sup 8/ amu/Q, where Q is the particle charge) may detect these grains. The model can explain observations made by the ASPERA mass spectrometer during the PHOBOS mission when signals in the mass channels 10/sup 3/-10/sup 7/ amu were detected inside the Martian magnetosphere. The evolution of a grain orbiting Mars is shown in a diagram of the particle size-particle potential. Such a diagram gives a qualitative picture of the grain interaction with the Martian plasma environment. >

Viking electron energy spectrogram (ESP) and positive ion energy spectrogram (PISP) data show that there is a thin and faint but distinguishable region at the poleward edge of the cusp-cleft region. This region is characterized by 100- to 300-eV field-aligned electrons with no striking ion feature except for coexisting low-energy upward ions. These faint electron beams are almost always observed unless the interplanetary magnetic field (IMF) is southward, yet they are different from the polar arcs, boundary cusp electrons, and the merging type electron burst on merging field lines for the following reasons. First, the thickness of this region (very thin) and the electron beams' pitch angle distribution of this region are clearly different from those of the boundary cusp or the polar arc region. Second, these electron beams are observed during weak IMF when the ions do not show any merging-associated energy dispersion. This region sometimes exists even when the merging line is located on the other (equatorward) side of the cusp, indicating that these electron beams are not the merging-related electron burst. Third, this region is absent near local noon (1130-1230 MLT). The electron beams are found rather on the morningside and the afternoonside. This special distribution is not expected for polar arcs or merging-related electron bursts. The absence of the thin electron beam region near local noon indicates, together with its latitudinal location (always between the cusp and the polar cap or polar arcs), that the tail boundary layer can be a possible source of these electron beams. Since this newly found region is very thin and it is always located between the cusp and polar cap or polar arcs, we call it the “cusp poleward edge,” despite its absence near local noon.

Thin-skinned extension on a salt detachment, of a style known as raft tectonics, characterizes deformation of the late Aptian to Recent section in the northern Kwanza Basin, Angola. Large rafts and intervening grabens are interpreted to have developed as a result of gravity gliding (increased dip) and gravity spreading (asymmetrical loading of a sedimentary wedge). Major raft movement occurred primarily from the Middle Tertiary, but some deformation appears to have started as early as late Cenomanian or early Turonian times. Individual grabens measure up to 70 km in length, 15 km in width and nearly 3 km in depth, and show switching polarities in the sense of thickening of the Tertiary sedimentary infill. Graben geometries were controlled by syndepositional extension and the local availability of salt. From the data examined, which includes both seismic and well data, the grabens appear to become younger from east to west, reflecting basinward progression of the deformation. As the age relationships could be related to insufficient sampling of strata deposited in complex sedimentation patterns, they may have no relevance to the timing of the deformation; the diachronous deformation is therefore speculative. Extension in the northern Kwanza Basin is estimated at 60%; the outermost raft is translated ≈55 km westwards. In addition to the extensional structures, compressional folds, thrust faults and salt structures mark the toe of the gravity gliding and spreading system. All of the rafts lie within the African portion of the Aptian Salt Basin, on rifted continental crust, and they are generally unrelated to structures below the salt. Biostratigraphy and lithostratigraphy indicate that the grabens formed on the shelf and upper slope from the Middle Eocene. Associated compressional features developed near the slope rise. The unusual expression of raft tectonics is attributed to a combination of: (1) the presence of a salt layer; (2) a stable basement configuration that allowed quiescent accumulation of the raft sequence; and (3) an increase in basin dip and sediment supply.

We use whistler waves observed close to the magnetopause as an instrument to investigate the internal structure of the magnetopause-magnetosheath boundary layer. We find that this region is characterized by tube-like structures with dimensions less than or comparable with an ion inertial length in the direction perpendicular to the ambient magnetic field. The tubes are revealed as they constitute regions where whistler waves are generated and propagate. We believe that the region containing tube-like structures extend several Earth radii along the magnetopause in the boundary layer. Within the presumed wave generating regions we find current structures moving at the whistler wave group velocity in the same direction as the waves.

The SMART-1 mission has recently arrived at the Moon. Its payload includes D-CIXS, a compact X-ray spectrometer. SMART-1 is a technology evaluation mission, and D-CIXS is the first of a new generation of planetary X-ray spectrometers. Novel technologies enable new capabilities for measuring the fluorescent yield of a planetary surface or atmosphere which is illuminated by solar X-rays. During the extended SMART-1 cruise phase, observations of the Earth showed strong argon emission, providing a good source for calibration and demonstrating the potential of the technique. At the Moon, our initial observations over Mare Crisium show a first unambiguous remote sensing of calcium in the lunar regolith. Data obtained are broadly consistent with current understanding of mare and highland composition. Ground truth is provided by the returned Luna 20 and 24 sample sets. (c) 2006 Elsevier Ltd. All rights reserved.

LISA is a circularly polarized, planar array antenna providing an inter-satellite link between an LEO and GEO satellite. Within this paper the basic design concept of the antenna, results of a two element breadboard model and performance tests of the full 16 element antenna are presented. The radiation patterns predicted with an electrical field simulation program are in close agreement with co- and cross-polar radiation pattern measured in a compensated compact antenna test range. (6 pages)