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Long-lived, persistently active lava lakes are rare but have been studied extensively because they may provide a natural laboratory for studying magmatic convection in basaltic and other low-viscosity volcanoes. However, lava lakes differ from other volcanic systems in various ways, particularly geometry: the presence of the lava lake requires a sudden and significant flaring of the conduit. The goal of this paper is to advance our understanding of the effect that a sudden increase in the conduit width has on the stability of large gas slugs and bubbles ascending from the plumbing system. We investigate this question by linking analog laboratory experiments to direct numerical simulations in two dimensions. We find that the rapid change in the geometry associated with the transition from the conduit to the lava lake causes large gas slugs to break up. The nondimensional regime over which we observe the breakup depends sensitively on the flare angle of the lava lake and the importance of inertial effects in the flow, implying that degassing-related eruptive activity at open-system volcanoes is sensitive to the upper conduit and lake geometries. Applying this idea to the likely geometries and viscosities of actual lava lakes, our study suggests that all lava lakes except Erebus fall well within the regime where large gas slugs are prone to breakup.

Eine 49-jahrige Patientin stellte sich mit einem diffusen Beschwerdebild mit Polydipsie, seit Wochen zunehmender Mudigkeit und unspezifischen abdominellen Schmerzen vor. Bei Kalzium im Serum von 5,30 mmol/l (RB: 2,00–2,60), Parathormon von > 2500,0 ng/l (RB: 15,0–68,0) und einer mediastinalen Raumforderung wurde die Diagnose einer hyperkalzamischen Krise auf dem Boden eines primaren Hyperparathyreoidismus gestellt. Nach intensivstationarer Stabilisierung erfolgte die Parathyreoidektomie eines Nebenschilddrusenadenoms. Der postoperative Verlauf war weitgehend komplikationslos.

Finding sought visual targets requires our brains to flexibly combine working memory information about what we are looking for with visual information about what we are looking at. To investigate the neural computations involved in finding visual targets, we recorded neural responses in inferotemporal (IT) and perirhinal (PRH) cortex as macaque monkeys performed a task that required them to find targets within sequences of distractors. We found similar amounts of total task-specific information in both areas, however, information about whether a target was in view was more accessible using a linear read-out (i.e. was more “untangled”) in PRH. Consistent with the flow of information from IT to PRH, we also found that task-relevant information arrived earlier in IT. PRH responses were well-described by a functional model in which “untangling” computations in PRH reformat input from IT by combining neurons with asymmetric tuning correlations for target matches and distractors.

Phreatic eruptions, although posing a serious threat to people in crater proximity, are often underestimated and have been comparatively understudied. The detailed eruption catalogue for Ruapehu Volcano (New Zealand) provides an exceptional opportunity to study the statistics of recurring phreatic explosions at a crater lake volcano. We performed a statistical analysis on this phreatic eruption database, which suggests that phreatic events at Ruapehu do not follow a Poisson process. Instead they tend to cluster, which is possibly linked to an increased heat flow during periods of a more shallow-seated magma column. Larger explosions are more likely to follow shortly after smaller events, as opposed to longer periods of quiescence. The absolute probability for a phreatic explosion to occur at Ruapehu within the next month is about 10%, when averaging over the last 70 years of recording. However, the frequency of phreatic explosions is significantly higher than the background level in years prior to magmatic episodes. Combining clast ejection simulations with a Bayesian event tree tool (PyBetVH) we perform a probabilistic assessment of the hazard due to ballistic ejecta in the summit area of Ruapehu, which is frequently visited by hikers. Resulting hazard maps show that the absolute probability for the summit to be affected by ballistics within the next month is up to 6%. The hazard is especially high on the northern lakeshore, where there is a mountain refuge. Our results contribute to the local hazard assessment as well as the general perception of hazards due to steam-driven explosions.

Growing evidence for significant magmatic vesiculation prior to magma-water interaction (MWI) has brought into question the use of ‘diagnostic’ features, such as low vesicularities and blocky morphologies, to identify hydromagmatic pyroclasts. We address this question by quantifying co-variations in particle size, shape and texture in both magmatic and hydromagmatic deposits from the Hverfjall Fires fissure eruption, Iceland. Overlapping vesicularity and bubble number density distributions measured in rapidly quenched magmatic and hydromagmatic pyroclasts indicate a shared initial history of bubble nucleation and growth, with substantial vesiculation prior to MWI. Hydromagmatic fragmentation occurred principally by brittle mechanisms, where the length scale and geometry of fracturing was controlled by the bubble population. This suggests that the elevated fragmentation efficiency of hydromagmatic deposits is driven, at least in part, by brittle disintegration of vesicular pyroclasts due to high thermal stress generated during rapid cooling. In this way, the shape and size distributions of hydromagmatic pyroclasts, both critical input parameters for ash dispersion models, are strongly influenced by the dynamics of vesiculation prior to MWI. This result underlines the need to analyse multiple grain-size fractions to characterise the balance between magmatic and hydromagmatic processes. During the Hverfjall Fires eruption, the external water supply was sufficient to maintain MWI throughout the eruption, with no evidence for progressive exhaustion of a water reservoir. We suggest that both the longevity and the spatial distribution of MWI were determined by the pre-existing regional hydrology and represent continuous interaction between a propagating dike and a strong groundwater flow system hosted within permeable basalt lavas., This work was completed with support for KVC from the AXA Research Fund and a Royal Society Wolfson Merit Award, a Royal Society URF to ACR and a University of Bristol postgraduate Scholarship to EJL. Fieldwork was supported by a New Researchers Award from the Geologists’ Association to EJL. We thank S. Kearns and B. Buse for their assistance with SEM analysis.

Crystal-rich intermediate magmas are subjected to both primary and secondary fragmentation processes, each of which may produce texturally distinct tephra. Of particular interest for volcanic hazards is the extent to which each process contributes ash to volcanic plumes. One way to address this question is by fragmenting pyroclasts under controlled conditions. We fragmented pumice samples from Soufriere Hills Volcano (SHV), Montserrat, by three methods: rapid decompression in a shock tube-like apparatus, impact by a falling piston, and milling in a ball mill. Grain size distributions of the products reveal that all three mechanisms produce fractal breakage patterns, and that the fractal dimension increases from a minimum of ~ 2.1 for decompression fragmentation (primary fragmentation) to a maximum of ~ 2.7 by repeated impact (secondary fragmentation). To assess the details of the fragmentation process, we quantified the shape, texture and components of constituent ash particles. Ash shape analysis shows that the axial ratio increases during milling and that particle convexity increases with repeated impacts. We also quantify the extent to which the matrix is separated from the crystals, which shows that secondary processes efficiently remove adhering matrix from crystals, particularly during milling (abrasion). Furthermore, measurements of crystal size distributions before (using x-ray computed tomography) and after (by componentry of individual grain size classes) decompression-driven fragmentation show not only that crystals influence particular size fractions across the total grain size distribution, but also that free crystals are smaller in the fragmented material than in the original pumice clast. Taken together, our results confirm previous work showing both the control of initial texture on the primary fragmentation process and the contributions of secondary processes to ash formation. Critically, however, our extension of previous analyses to characterisation of shape, texture and componentry provides new analytical tools that can be used to assess contributions of secondary processes to ash deposits of uncertain or mixed origin. We illustrate this application with examples from SHV deposits.

Linear-nonlinear (LN) models and their extensions have proven successful in describing transformations from stimuli to spiking responses of neurons in early stages of sensory hierarchies. Neural responses at later stages are highly nonlinear and have generally been better characterized in terms of their decoding performance on prespecified tasks. Here we develop a biologically plausible decoding model for classification tasks, that we refer to as neural quadratic discriminant analysis (nQDA). Specifically, we reformulate an optimal quadratic classifier as an LN-LN computation, analogous to “subunit” encoding models that have been used to describe responses in retina and primary visual cortex. We propose a physiological mechanism by which the parameters of the nQDA classifier could be optimized, using a supervised variant of a Hebbian learning rule. As an example of its applicability, we show that nQDA provides a better account than many comparable alternatives for the transformation between neural representations in two high-level brain areas recorded as monkeys performed a visual delayed-match-to-sample task

Quantitative textural analyses including crystal size distributions (CSDs) provide insights into crystallisation kinetics of magmatic systems. Investigations of volcanic crystal textures often rely on greyscale variations on backscattered electron images to identify crystal phases, which must then be thresholded and/or traced manually, a laborious task, and investigations are typically restricted to a single crystal phase. A method is presented that uses energy-dispersive X-ray element maps to generate textural data. Each pixel is identified as a crystal phase, glass or vesicle according to relative chemical composition enabling concurrent acquisition of multiphase CSD, crystallinity and mineral mode data. Data processing is less time intensive for the operator but considerable instrument time is required to generate element maps. The method is applied to 17 dacite samples from the 1980–1986 and 3 from the 2004–2005 eruptive periods of Mount St. Helens volcano (USA) to provide quantitative insights into multiphase textural evolution. All of the CSDs are curved and concave-up in the standard CSD plot with curvature increasing with plagioclase content. To facilitate comparisons with previous studies, CSDs for microlites (

SummaryMost neurons in cortical area MT (V5) are strongly direction selective [1–4], and their activity is closely associated with the perception of visual motion [reviewed in 5]. These neurons have large receptive fields built by combining inputs with smaller receptive fields that respond to local motion [6]. Humans integrate motion over large areas and can perceive what has been referred to as global motion. The large size and direction selectivity of MT receptive fields suggests that MT neurons may represent global motion. We have explored this possibility by measuring responses to a stimulus in which the directions of simultaneously presented local and global motion are independently controlled. Surprisingly, MT responses depended only on the local motion and were unaffected by the global motion. Yet, under similar conditions, human observers perceive global motion and are impaired in discriminating local motion. Although local motion perception might depend on MT signals, global motion perception depends on mechanisms qualitatively different from those in MT. Motion perception therefore does not depend on a single cortical area but reflects the action and interaction of multiple brain systems.

Volcanic infrasound from explosive eruptions is detectable at distances up to 1000 s of km and is often recorded on the International Monitoring System (IMS) infrasound network. Though infrasound produced by individual volcanoes has previously been studied, more general relationships between infrasound characteristics and eruption parameters remain unclear. Therefore, using a dataset comprising 110 events at 39 globally distributed volcanoes, we assess the ability of the IMS to monitor remote volcanoes and investigate whether volcanic infrasound exhibits consistent trends across a range of eruption styles and intensities. Acoustic pressure amplitude and frequency content of the volcanic infrasound were measured, and acoustic energy was also calculated. These were compared, along with the maximum distance of detection for each event, to the maximum plume height reported for the event, which was used as a proxy for event intensity. Of the events investigated 62% were detected by at least one infrasound station. The maximum distance at which an event was detected generally increased with the plume height, and infrasound produced during the eruption of Manam, PNG in January 2005, which produced a plume which rose over 20 km above the summit, was detected at a distance of 10,671 km. Total acoustic energy and acoustic pressure amplitude (corrected for geometrical spreading) increased with plume height, whilst the lowest frequency present in the volcanic infrasound decreased. Additionally, relationships seen between infrasound characteristics and eruption plume height indicate that analyses of this data alone could constrain vital estimates of plume heights for otherwise un-observed eruptions. Taken together these findings indicate that if made available for this purpose in the future, the IMS infrasound network could complement existing monitoring techniques by detecting and characterising eruptions at remote volcanoes which often have no local monitoring networks.

We present an experimental study of a buoyancy-driven, low-Reynolds-number (Re < 1) exchange flow of two Newtonian fluids in a vertical cylindrical pipe (length 1 m and diameter 38.4 mm) connecting two fluid reservoirs. The denser, more viscous fluid was golden syrup and the less dense, less viscous fluid was a golden syrup–water solution; the ratio of the viscosities of the two fluids (β) ranged from 2 to 1180. Flows were initiated by removing a bung in the base of the upper reservoir or sliding out a gate positioned at the top, middle or bottom of the pipe. We observe the flows over long time durations (up to 356 h), and define the development of the flow with reference to a non-dimensional time (τ). The initial transient development of the flow was dependent on which of the two fluids initially filled the pipe, but this did not systematically affect the flow regime observed at τ ≫ 1. Two distinct flow regimes were observed: axisymmetric core-annular flow (CAF), in which the less viscous fluid occupies a cylindrical core and the denser fluid flows downwards in an annulus, and side-by-side (SBS) flow where both fluids are in contact with the pipe and there is a single interface between them. CAF formed at β ≥ 75 and SBS flow at β ≤ 117. In several experiments, for 5 ≤ β ≤ 59, a slowly developing transitional SBS (TSBS) flow was observed where SBS flow and CAF occurred simultaneously with SBS in the lower portion of the pipe; SBS existed throughout most of the pipe and in one case grew with time to entirely fill the pipe. Velocity profiles determined by tracking tracer particles show that the observed CAFs are adequately described by the formulation of Huppert & Hallworth (J. Fluid Mech., vol. 578, 2007, pp. 95–112). Experimental SBS velocity profiles are not well produced by the formulation of Kerswell (J. Fluid Mech., 10.1017/jfm.2011.190), possibly because the latter is restricted to flows whose cross-section has an interface of constant curvature. Despite the variations in flow regime, volume fluxes can be described by a power-law function of β, Q1 = 0.059 β−0.74. A comparison of experimental data with the theoretical approaches of Huppert Hallworth (2007) and Kerswell (2011) indicates that fluids are not arranged in the regime that maximises volume flux (e.g. SBS or CAF), nor do they adopt the geometry that maximises volume flux within that particular regime.

The ability of Myc to promote cellular transformation is well established; however, a better understanding of the mechanisms through which Myc mediates tumorigenesis is essential for the development of therapeutic approaches to target this potent oncoprotein. Structure-function studies in rodent fibroblast cells have provided the basis for much of our current understanding of these mechanisms. To build on these approaches, we have characterized three novel human cell line models of Myc-dependent transformation: MCF10A, SH-EP Tet21/N-Myc, and LF1/TERT/LT/ST cells. We have also evaluated Myc family proteins (c-Myc and L-Myc), a naturally occurring isoform of Myc (MycS), and a set of N-terminal domain mutants (ΔMBII, W135E, T58A) for their ability to promote anchorage-independent growth in these models. Taken together, these results provide the field with three new human cell-based models to study Myc activity, highlight the importance of cellular context, and challenge the paradigm that the ability of Myc to promote tumorigenesis is exclusively MBII-dependent.

The configuration of subvolcanic magma storage regions exercises a fundamental control on eruptive style and hazard. Such regions can be imaged remotely, using seismic, geodetic, or magnetotelluric methods, although these are far from routine and rarely unambiguous. The textures of erupted volcanic rocks, as quantified through crystal size distributions (CSD), provide space- and time-integrated information on subvolcanic plumbing systems, although these data cannot be used readily for reconstruction of key parameters such as conduit geometry or magma chamber depth. Here we develop a numerical approach to interpretation of CSD in products of steady eruptions, based on crystallization kinetics and hydrodynamic flow simulation, to image subvolcanic plumbing systems. The method requires knowledge of magma properties, crystal growth kinetics (measured experimentally), and discharge rate (measured observationally). The method is applicable to steady-state eruptive regimes. Distributions of pressure, temperature, crystal content, and conduit cross-section area with depth are obtained from a CSD from a sample erupted from Mount St. Helens volcano, USA. Values of average conduit diameter (∼30 m) and magma chamber depth (∼14 km below the summit) are in good agreement with independent estimates.

The emerging concept of a magma reservoir is one in which regions containing melt extend from the source of magma generation to the surface. The reservoir may contain regions of very low fraction intergranular melt, partially molten rock (mush) and melt lenses (or magma chambers) containing high melt fraction eruptible magma, as well as pockets of exsolved magmatic fluids. The various parts of the system may be separated by a sub-solidus rock or be connected and continuous. Magma reservoirs and their wall rocks span a vast array of rheological properties, covering as much as 25 orders of magnitude from high viscosity, sub-solidus crustal rocks to magmatic fluids. Time scales of processes within magma reservoirs range from very slow melt and fluid segregation within mush and magma chambers and deformation of surrounding host rocks to very rapid development of magma and fluid instability, transport and eruption. Developing a comprehensive model of these systems is a grand challenge that will require close collaboration between modellers, geophysicists, geochemists, geologists, volcanologists and petrologists. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’.

Jak P. Mallmann Showell requires no intro- duction to students of the Battle of the Atlantic. In some 40 book-length and shorter works authored or edited over the span of some three decades in Engl...

The rheology of suspensions of cubic crystals in viscous liquids was investigated with a series of experiments, consisting of the release of a fixed volume of fluid inside a horizontal channel. A Herschel–Bulkley rheology was assumed and the consistency K and the shear rate exponent n of this constitutive equation were calculated using the evolution of the flow front; the yield strength was calculated using the final shape of the flow. A solid fraction by volume of ϕ = 0–0.67 and a liquid viscosity range of 1–370 Pa s were used in the experiments. Results show an increase in K when crystal content increases. The mixtures start to show a shear thinning behaviour at ϕ ~ 0.3 with n values going from approximately 1 (Newtonian behaviour) to 0.5 at ϕ = 0.6. Yield strength was detected at the same ϕ as the beginning of shear thinning behaviour and increases with a power-law relationship with crystal content. Suspensions with bimodal size distribution of crystals show a dramatic decrease of the apparent viscosity compared to unimodal suspensions, especially at the higher total crystal concentrations. The results were applied to theoretical 2-D flows on a slope, showing large variations in velocity profiles for the same crystallinity depending on the rheology assumed. A case study of a 2002 lava flow from Etna volcano demonstrates that measured lava flow speeds are similar to speeds calculated from 2-D theory with rheologies of lava based on laboratory experiments and measured lava crystal content. The results illustrate that the dynamics of lava flows depend on the crystal size distribution in addition to the total crystal concentration.

The visual system is tasked with extracting stimulus content (e.g. the identity of an object) from the spatiotemporal light pattern falling on the retina. However, visual information can be ambiguous with regard to content (e.g. an object when viewed from far away), requiring the system to also consider contextual information. Additionally, visual information originating from the same content can differ (e.g. the same object viewed from different angles), requiring the system to extract content invariant to these differences. In this review, we explore these challenges from experimental and theoretical perspectives, and motivate the need to incorporate solutions for both ambiguity and invariance into hierarchical models of visual processing.

Gas loss from ascending magma controls the chemical and physical evolution of volcanic systems. Melt inclusions trapped in volcanic phenocrysts contain snapshots of volatile evolution, but are notoriously hard to interpret in terms of conventional degassing models because gas fluxing, diffusive re-equilibration and external sources can also contribute to the volatile budget. Here we supplement published melt inclusion volatile data from a wide range of volcanoes with new ion-microprobe data on H2O, CO2, Be, B, Li and Sc in melt inclusions from the 1980–1986 eruptions of Mount St. Helens. The new and published data demonstrate that suites of melt inclusions are typically displaced to higher CO2 contents than would be predicted from calculated open or closed-system degassing trends. We reconcile all CO2–H2O data into a coherent framework based on the ratio of gas to melt during eruption. Interaction of shallow-stored magmas with vapours released from deeper in the magma system displaces melts to CO2-rich compositions. Our observations require that arc magmas are significantly more CO2-rich than is estimated from melt inclusions alone because of the low probability of trapping high CO2 melts during magma ascent. We illustrate this process with calculations in the model system albite–H2O–CO2.

The development of thermal convection is studied for a viscoplastic fluid. If the viscosity is finite at zero shear rate, the critical Rayleigh number for linear instability takes the value given by a Newtonian fluid with that viscosity. The subsequent weakly nonlinear behaviour depends on the degree of shear thinning: with moderate shear thinning, convective overturning for a given temperature difference is amplified relative to the Newtonian case. If the reduction in viscosity is sufficiently sharp the transition becomes subcritical (the relevant situation for many regularized constitutive laws). For an infinite viscosity at zero shear rate, or a yield-stress, the critical Rayleigh number for linear instability is infinite. Nonlinear convective overturning, however, is still possible; we trace out how the finite-amplitude solution branches develop from their Newtonian counterparts as the yield stress is increased from zero for the Bingham fluid. Laboratory experiments with a layer of Carbopol fluid heated from below confirm that yield strength inhibits convection but a sufficiently strong perturbation can initiate overturning.

A 47-year-old dog breeder had suffered from unclassified polyarthritis for four years. During immunomodulatory therapy of an assumed seronegative chronic polyarthritis with Leflunomid and Adalimumab he developed severe systemic inflammatory disease with high fever, weight loss, and severe arthralgia. Fever and arthralgias temporarily improved under antibiotic therapy, although a causative organism had not been found. The clinical picture led to the differential diagnosis of Whipple's disease, but PAS-positive macrophages were not detected in duodenal biopsies. The diagnosis was finally based on a positive PCR result for Tropheryma whipplii, typical clinical symptoms and a complete response on adequate antibiotic long-term treatment with cotrimoxazol. The diagnosis of Whipple's disease was possibly masked by the initial antibiotic therapies. Therapies with immunomodulators, TNF-inhibitors, and corticosteroids may transform an infection with Tropheryma whipplii, normally in a subacute stage, into a septic, life-threatening disease.

This multicentre phase II study evaluated the efficacy and safety of preoperative capecitabine plus oxaliplatin and radiotherapy (RT) in patients with locally advanced rectal cancer (T3/T4 rectal adenocarcinoma with or without nodal involvement). Treatment consisted of one cycle of XELOX (capecitabine 1000 mg m(-2) bid on days 1-14 and oxaliplatin 130 mg m(-2) on day 1), followed by RT (1.8 Gy fractions 5 days per week for 5 weeks) plus CAPOX (capecitabine 825 mg m(-2) bid on days 22-35 and 43-56, and oxaliplatin 50 mg m(-2) on days 22, 29, 43 and 50). Surgery was recommended 5 weeks after completion of chemoradiotherapy. The primary end point was pathological complete tumour response (pCR). Sixty patients were enrolled. In the intent-to-treat population, the pCR rate was 23% (95% CI: 13-36%). 58 patients underwent surgery; R0 resection was achieved in 57 (98%) patients, including all 5 patients with T4 tumours. Sphincter preservation was achieved in 49 (84%) patients. Tumour and/or nodal downstaging was observed in 39 (65%) patients. The most common grade 3/4 adverse events were diarrhoea (20%) and lymphocytopaenia (43%). Preoperative capecitabine, oxaliplatin and RT achieved encouraging rates of pCR, R0 resection, sphincter preservation and tumour downstaging in patients with locally advanced rectal cancer.

Oscillations generated by flow of magmatic or hyrothermal fluids through tabular channels in elastic rocks are a possible source of low frequency seismicity. We assess the conditions required to generate oscillations of ∼1Hz via hydrodynamic flow instabilities, flow-destabilized standing waves set up on the channel walls, and unstable normal modes ringing in an adjacent fluid reservoir. Flow destabilized modes offer the most plausible explanation, but there are limitations on what kind of standing waves comprises them.

Fudge is an excellent analog for basaltic lava and making or tasting fudge leads to memorable lessons on the importance of crystals in controlling the morphology of basaltic lava flows. In particular, students learn why ‘a’a flows have rough broken surfaces, while pahoehoe flows are smooth or folded. Furthermore, fudge provides an interesting analog in lessons on the factors that control crystal nucleation and growth as well as how crystals affect magma rheology. Although the full process of making fudge from scratch is too long for a lecture demonstration, fudge can be incorporated into lessons on basalt flows by way of taste-tests, photographs or simplified experiments with pre-made fudge and syrup. Advanced students can run experiments during a laboratory period and examine the crystal textures under a microscope, or do their own experiments in small groups outside of the classroom. Evaluation with written quizzes shows that fudge demonstrations can be an effective aid for teaching the complex concepts...

We are developing methods for imaging multiple PET tracers in a single scan with staggered injections, where imaging measures for each tracer are separated and recovered using differences in tracer kinetics and radioactive decay. In this work, signal separation performance for rapid dual-tracer (62)Cu-PTSM (blood flow) + (62)Cu-ATSM (hypoxia) tumor imaging was evaluated in a large animal model. Four dogs with pre-existing tumors received a series of dynamic PET scans with (62)Cu-PTSM and (62)Cu-ATSM, permitting evaluation of a rapid dual-tracer protocol designed by previous simulation work. Several imaging measures were computed from the dual-tracer data and compared with those from separate, single-tracer imaging. Static imaging measures (e.g. SUV) for each tracer were accurately recovered from dual-tracer data. The wash-in (k(1)) and wash-out (k(2)) rate parameters for both tracers were likewise well recovered (r = 0.87-0.99), but k(3) was not accurately recovered for PTSM (r = 0.19) and moderately well recovered for ATSM (r = 0.70). Some degree of bias was noted, however, which may potentially be overcome through further refinement of the signal separation algorithms. This work demonstrates that complementary information regarding tumor blood flow and hypoxia can be acquired by a single dual-tracer PET scan, and also that the signal separation procedure works effectively for real physiologic data with realistic levels of kinetic model mismatch. Rapid multi-tracer PET has the potential to improve tumor assessment for image-guide therapy and monitoring, and further investigation with these and other tracers is warranted.

We review viscoplastic flow over inclined surfaces, focusing on constant-flux extrusions from small vents and the slumping of a fixed volume of material. Lubrication theory is used for shallow and slow flows to reduce the governing equations to a non-linear diffusion-type equation for the local fluid depth; this model is used as the basis for exploration of the problem. Theory is compared to experiments. A number of complications and additional physical effects are discussed that enrich real situations.

Context The dental setting represents an unrealized opportunity to increase adherence to preventive services and improve health outcomes. Objective To compare adherence to a subset of Healthcare Effectiveness Data and Information Set (HEDIS) measures among a population that received dental care with a population that did not receive dental care. Design Using a retrospective cohort design, we identified 5216 adults who received regular dental care and 5216 persons who did not. The groups were matched on propensity scores, were followed for 3 years, and retained medical and dental benefits. Receipt of dental care was defined as 1 or more dental visits in each 12-month period. Main outcome measures Outcome measures were assessed in a subpopulation that qualified for 1 of 5 HEDIS denominator groups (dental = 4184 patients; nondental = 3871 patients). They included 3 preventive measures (cervical, colorectal, and breast cancer screening), 4 chronic disease management services (hemoglobin A1c and low-density lipoprotein cholesterol testing, and nephropathy and retinopathy screening among the diabetes mellitus [DM] population), and 4 health outcome measures (poor glycemic control, low-density lipoprotein cholesterol control, blood pressure control in the DM population, and blood pressure control in the hypertensive population). Results Dental care was associated with higher adherence to all three cancer screening measures, one of four disease management services (higher retinopathy screening), and three of four health outcomes (better glycemic control in the DM population and better blood pressure control in the DM and hypertensive populations). Conclusions Dental care was associated with improved adherence to 7 of 11 HEDIS measures.

International audience; The 18 May 1980 eruption of Mount St. Helens started with a lateral blast that fed a pyroclastic surge, which then uplifted to form a co-blast plume. Thirty minutes later, Plinian activity started at the vent and fluctuated in intensity for ~9 h. The resulting fallout deposit, documented to > 600 km from vent, presents some striking features: (1) displacement of the overall deposit to the north of the vent, (2) a secondary thickness and mass maximum at ~300 km from vent, (3) a total grain size distribution dominated by fine ash (62 wt % of the deposit < 63 μm), and (4) individual grain size distributions that vary dramatically in the crosswind direction from strongly bimodal in the south to skewed unimodal in the north. Results from a new deconvolution of the individual grain size distributions show that they are a combination of a coarse subpopulation that decreases in size with distance from vent and a constant fine subpopulation with a mean of ∼15 μm. Relative proportions of each subpopulation vary asymmetrically in the crosswind directions, with the fine subpopulation preponderant toward the north and the coarse one dominating the south of the deposit, both reach their absolute maxima in mass on the deposit axis. Componentry analyses of selected samples show that blast-derived material is greatly enriched toward the north of the deposit. These results indicate that the co-blast plume dispersed fine-grained material over great distances and dominated the fine subpopulation. Comparison with reanalysis data of atmospheric wind fields and satellite images of the spreading ash cloud suggests contrasting ash transport and depositional processes for the (early) co-blast plume and the (later) vent-derived Plinian plumes. The co-blast plume is displaced to the north; it had a high overshoot height, and eastward dispersion via strong winds low in the stratosphere (~10-15 km). The Plinian plumes were lower and dispersed most of the material to the southeast as the direction of high-velocity winds shifted just before the late climactic Plinian eruptive phase. Fine ash (fine subpopulation) was deposited continuously throughout the deposit, with an increase of sedimentation rate ~300 km from the vent where there is a secondary maximum in the deposit mass and thickness. Fine ash probably settled by a combination of enhanced sedimentation mechanisms, including not only aggregation but also gravitational convective instabilities of cloud base, hydrometeor formation and destruction, and entrainment of small particles by larger ones. Finally, we show that half of the deposit (by mass) in the medial area was deposited by the co-blast plume, and that a significant proportion of the Mount St. Helens fallout deposit is nonjuvenile, which has implications for the magmatic budget of this eruption.

article i nfo Magmatic hydrothermal systems develop by the imposition of a magmatically derived heat flux upon a shallow groundwater system. As such their dynamics can be intermittently perturbed by changing conditions within the associated magmaticsystem. Understanding thenature of the coupling between the magmaticand groundwater systems is thus key to discriminating geophysical signals of magmatic unrest from purely hydrothermal ones. Using a series of numerical groundwater models run with TOUGH2, we simulate the coupled groundwater- magmatic system at Campi Flegrei caldera, with particular emphasis on the impact of permeability devel- oped within local fault systems and the dynamics of thesystem during magmatic unrest. Simulation results suggestthatfaultscanplayanimportantroleincontrollingthedynamicsofrechargeandheattransportwithinthe shallow hydrothermal reservoir. Results specifically highlight that contrasts in permeability between faults and surrounding rock impact local temperature gradients, with faults either acting as preferential routes for recharge or discharge of groundwater, depending on fault/caldera fill permeability contrast and the vertical extent of the fault.Simulationsofmagmaticunrestwithastep-wiseincreaseinbasalheat flux suggest that periodicgeophysical and chemical signals may stem from the interaction between the development of gas at depth and the recharge-discharge dynamics of the reservoir. These results highlight the potential for the dynamics of magmatic-hydrothermal systems to be significantly impacted by the presence and nature of local fault systems. Wheredynamicgroundwatersystemsare involved,itisthusimportanttounderstandtheimpactofsuchgeolog- ical elements when interpreting monitoring data such as ground deformation, seismicity and gas emissions. © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license

We present isothermal (885 °C) phase equilibrium experiments for a rhyodacite from Mount St. Helens (USA) at variable total pressure (25–457 MPa) and fluid composition (XH2Ofl = 0.6–1.0) under relatively oxidizing conditions (NNO to NNO + 3). Run products were characterized by SEM, electron microprobe, and SIMS. Experimental phase assemblages and phase chemistry are consistent with those of natural samples from Mount St. Helens from the last 4000 years. Our results emphasize the importance of pressure and melt H2O content in controlling phase proportions and compositions, showing how significant textural and compositional variability may be generated in the absence of mixing, cooling, or even decompression. Rather, variations in the bulk volatile content of magmas, and the potential for fluid migration relative to surrounding melts, mean that magmas may take varied trajectories through pressure–fluid composition space during storage, transport, and eruption. We introduce a novel method for projecting isothermal phase equilibria into CO2–H2O space (as conventionally done for melt inclusions) and use this projection to interpret petrological data from Mount St. Helens dacites. By fitting the experimental data as empirical functions of melt water content, we show how different scenarios of isothermal magma degassing (e.g., water-saturated ascent, vapor-buffered ascent, and vapor fluxing) can have quite different textural and chemical consequences. We explore how petrological data might be used to infer degassing paths of natural magmas and conclude that melt CO2 content is a much more useful parameter in this regard than melt H2O.

Well water level changes associated with magmatic unrest can be interpreted as a result of pore pressure changes in the aquifer due to crustal deformation, and so could provide constraints on the subsurface processes causing this strain. We use Finite Element Analysis to demonstrate the response of aquifers to volumetric strain induced by pressurised magma reservoirs. Two different aquifers are invoked – an unconsolidated pyroclastic deposit and a vesicular lava flow – and embedded in an impermeable crust, overlying a magma chamber. The time-dependent, fully coupled models simulate crustal deformation accompanying chamber pressurisation and the resulting hydraulic head changes as well as porous flow in the aquifer. The simulated deformational strain leads to centimetres (pyroclastic aquifer) to meters (lava flow aquifer) of hydraulic head changes; both strain and hydraulic head change with time due to substantial porous flow in the hydrological system. Well level changes are particularly sensitive to chamber volume and shape, followed by chamber depth and the phase of the pore fluid. The Young's Modulus and permeability of the aquifer, as well as the strength of pressurisation also have significant influence on the hydraulic head signal. While source characteristics, the distance between chamber and aquifer and the elastic stratigraphy determine the strain field and its partitioning, flow and coupling parameters define how the aquifer responds to this strain and how signals change with time. We investigated a period of pre-eruptive head changes recorded at Usu volcano, Japan, where well data were interpreted using an analytical deformation model. We find that generic analytical models can fail to capture the complex pre-eruptive subsurface mechanics leading to well level changes, due to aquifer pressure changes being sensitive to chamber shape and lithological heterogeneities. In addition, the presence of a pore fluid and its flow have a significant influence on the strain signal in the aquifer and are commonly neglected in analytical models. These findings highlight the need for numerical models for the interpretation of observed well level signals. However, simulated water table changes do mirror volumetric strain and wells can therefore serve as comparatively cheap strain meters that could provide important insights into pre-eruptive dynamics.

Quantification of myocardial blood flows at rest and stress using 13N-ammonia PET is an established method; however, current techniques require a waiting period of about one hour between scans. The objective of this study was to test a rapid dual-injection single-scan approach, where 13N-ammonia injections are administered 10 minutes apart during rest and adenosine stress. Dynamic PET data were acquired in six human subjects using imaging protocols that provided separate single-injection scans as gold standards. Rest and stress data were combined to emulate rapid dual-injection data so that the underlying activity from each injection was known exactly. Regional blood flow estimates were computed from the dual-injection data using two methods: background subtraction and combined modeling. The rapid dual-injection approach provided blood flow estimates very similar to the conventional single-injection standards. Rest blood flow estimates were affected very little by the dual-injection approach, and stress estimates correlated strongly with separate single-injection values (r = 0.998; mean absolute difference = 0.06 ml/min/g). An actual rapid dual-injection scan was successfully acquired in one subject and further demonstrates feasibility of the method. This study with a limited dataset demonstrates that blood flow quantification can be obtained in only 20 minutes by the rapid dual-injection approach with accuracy similar to that of conventional separate rest and stress scans. The rapid dual-injection approach merits further development and additional evaluation for potential clinical use.

If you know nothing about the history of the U-boat campaign of the Second World War, Philip Kaplan's latest literary effort may be a reasonably priced and fairly entertaining, though far from flaw...

As parallel experimentation workflows become more complex, additional functionality and capability is required from laboratory robotics. These robotic platforms are no longer being used exclusively for liquid handling or for dedicated workflows but are being tasked to support a variety of analytical probes, heated tips, vial grippers, and a variety of other functions. To respond to this need, Symyx Technologies (Santa Clara, CA) has introduced the Extended Core Module (XCM) robotic system. The XCM features a robust robotic platform designed with a unique architecture that enables the straightforward addition of functionality through self-contained elements. These elements only require power, pneumatic connections (if required) and communication connections, which are provided by standard interfaces within the XCM deck. The XCM operates using Symyx Technologies, Inc. Renaissance® Software. Several workflows have been built using the Symyx XCM configurable architecture, encompassing both chemical and pharmaceutical workflows, and are described herein.

Positron emission tomography (PET) can characterize different aspects of tumor physiology using various tracers. PET scans are usually performed using only one tracer since there is no explicit signal for distinguishing multiple tracers. We tested the feasibility of rapidly imaging multiple PET tracers using dynamic imaging techniques, where the signals from each tracer are separated based upon differences in tracer half-life, kinetics, and distribution. Time-activity curve populations for FDG, acetate, ATSM, and PTSM were simulated using appropriate compartment models, and noisy dual-tracer curves were computed by shifting and adding the single-tracer curves. Single-tracer components were then estimated from dual-tracer data using two methods: principal component analysis (PCA)-based fits of single-tracer components to multitracer data, and parallel multitracer compartment models estimating single-tracer rate parameters from multitracer time-activity curves. The PCA analysis found that there is information content present for separating multitracer data, and that tracer separability depends upon tracer kinetics, injection order and timing. Multitracer compartment modeling recovered rate parameters for individual tracers with good accuracy but somewhat higher statistical uncertainty than single-tracer results when the injection delay was >10 min. These approaches to processing rapid multitracer PET data may potentially provide a new tool for characterizing multiple aspects of tumor physiology in vivo.

The stability of fluid flow through a narrow conduit with elastic walls is explored, treating the fluid as incompressible and viscous, and the walls as semi-infinite linear Hookean solids. Instabilities analogous to roll waves occur in this system; we map out the physical regime in which they are excited. For elastic wave speeds much higher than the fluid speed, a critical Reynolds number is required for instability. However, that critical value depends linearly on wavenumber, and so can be made arbitrarily small for long waves. For smaller elastic wave speeds, the critical Reynolds number is reduced still further, and Rayleigh waves can be destabilized by the fluid even at zero Reynolds number. A brief discussion is given of the nonlinear dynamics of the instabilities for large elastic wave speed, and the significance of the results to the phenomenon of volcanic tremor is presented. Although magma itself seems unlikely to generate flow-induced vibrations, the rapid flow through fractured rock of low-viscosity fluids exsolved from magma appears to be a viable mechanism for volcanic tremor.