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Background: The organization of healthcare could have an impact on the outcome of patients treated for acute cholecystitis (AC). The aim of this study was to analyze the way in which patients with AC are managed relative to the level of care by the treating hospital.Methods: Data were collected from the Swedish Register for Gallstone Surgery and ERCP (GallRiks). Cholecystectomies between 2010 and 2019 were included. The inclusion criterion was acute cholecystectomy in patients with AC operated at either tertiary referral centers (TRCs) or regional hospitals.Results: A total of 24,194 cholecystectomies with AC met the inclusion criterion. The time between admission and acute surgery was significantly elongated at TRCs compared with regional hospitals (2.2 ± 1.7 days vs. 1.6 ± 1.4 days, mean ± SD; p < 0.0001). Patients with a history of AC were more frequent at TRC (10.1% vs. 8.9%, p < 0.0056) and had a higher adverse event rate compared with those at regional hospitals (OR 1.61; CI 1.40-1.84, p < 0.0001). Surprisingly, an increased number of hospital beds correlated slightly with an increased number of days between admission and surgery (R2 = 0.132; p = 0.0075).Conclusion: Compared with regional hospitals, patients with AC had to wait longer at TRCs before surgery. A history of AC significantly increased the risk of adverse events. These findings indicate that logistic and organizational aspects of hospital care may affect the management of patients with AC. However, whether these findings can be generalized to healthcare organizations outside Sweden requires further investigation. [ABSTRACT FROM AUTHOR]

In this study, the influence of Soil-Structure Interaction (SSI) on the dynamic behavior of a three-span concrete slab railway bridge with integrated retaining walls is investigated. The bridge is subjected to controlled excitations using a hydraulic actuator with different frequencies and load amplitudes. A 3D model of the railway bridge-soil system is implemented and calibrated using the experimental frequency response functions at each sensor location. A soil-free model is also created to compare with the calibrated model. It is observed that the dynamic behavior of the railway bridge is substantially altered by the presence of the surrounding soils, and neglecting SSI can lead to underestimation and inaccurate results. Additionally, the calibrated model is used for further train-passage analyses. For the studied bridge, neglecting SSI increases the maximum acceleration response of the bridge during high-speed train passages from 5.5 m/s 2 up to 14.5 m/s 2. It is also shown that the response of the bridge during train passage is predominantly influenced by its first bending mode, with higher modes inducing no discernible effect. Finally, parametric studies are performed in order to study the uncertainties related to the soil properties. • A 3D model of a three-span railway bridge and the surrounding soils is analyzed. • Model calibration using forced vibration and train passage experiments. • SSI influences the dynamic response of the bridge during high-speed train passages. • Comparison between a soil-free model and the calibrated model. • Sensitivity analyses on different soil properties. [ABSTRACT FROM AUTHOR]

Short-span portal frame bridges are predominant in Swedish railway lines. Although it is well known that the dynamic response of these partially-buried rigid structures is governed by the surrounding soil, the effect of the soil is usually neglected in the train-induced vibration analysis due to the expensive computational costs. This paper focuses on studying the effect of the surrounding soil conditions on the dynamic response of portal frame railway bridges. The study aims to validate the accuracy of simplified numerical models in evaluating the dynamic stiffness and modal properties of the bridge–soil system. To achieve this aim, a model updating method was used for FE model calibration of a full–scale portal frame bridge using measured frequency response functions. Both measured and computed responses identify the substantial contribution of the surrounding soil on the global damping of the system and highlight the importance of the soil–structure interaction on the dynamic response of these structures. [ABSTRACT FROM AUTHOR]

Mainly because of the infamous incident with excessive vibrations of the London Millennium Bridge, the behavior of lively footbridges has been thoroughly studied lately. The liveliness of such bridges is strongly connected to various interaction effects between the pedestrians and the bridges. One such effect is the variation in the modal properties of the bridge, due to the presence of a crowd. In theoretical models of such systems, this is often accounted for by describing each pedestrian as a spring-mass-damper system, having its own dynamic properties, producing a time-variant system. A major drawback with models of this kind is that the computational time increases rapidly with the size of the system, i.e. for a larger crowd. Therefore, with the objective to reduce the computational time needed, this study focuses on describing vertical human-structure interaction by means of a simplified model. The paper describes a new methodology for taking this effect into consideration when predicting the dynamic response of a footbridge, subjected to human-induced, vertical loads. The method is used to predict the vertical bridge deck accelerations of a simply supported footbridge. The predictions produced by the proposed methodology are compared with existing models and it is shown that for certain bridges, it produces an accurate approximation at a significantly reduced computational cost. [ABSTRACT FROM AUTHOR]

This article presents preliminary theoretical results on the influence of dynamic soil-structure interaction (SSI) of slab foundations. Impedance functions, representing the dynamic SSI, were obtained from FE-models depicting the soil for a few cases of different geotechnical preconditions. The obtained impedance functions were attached to single-span bridges and HSLM-A analyses were performed. The effect of the impedance functions on the bridge response was studied and compared to the ultimate case of a bridge on rigid supports. The influence of SSI seems to have a significant effect on railway bridges. This study shows that by including this effect in bridge design, the damping ratio of the system is largely increased, giving lower acceleration amplitudes in the bridge, while the natural frequencies are less affected. [ABSTRACT FROM AUTHOR]

Air–sea gas transfer velocity for O 2 is calculated using directly measured fluxes with the eddy covariance technique. It is a direct method and is frequently used to determine fluxes of heat, humidity, and CO 2 , but has not previously been used to estimate transfer velocities for O 2 , using atmospheric eddy covariance data. The measured O 2 fluxes are upward directed, in agreement with the measured air–sea gradient of the O 2 concentration, and opposite to the direction of the simultaneously measured CO 2 fluxes. The transfer velocities estimated from measurements are compared with prominent wind speed parameterizations of the transfer velocity for CO 2 and O 2 , previously established from various measurement techniques. Our result indicates stronger wind speed dependence for the transfer velocity of O 2 compared to CO 2 starting at intermediate wind speeds. This stronger wind speed dependence appears to coincide with the onset of whitecap formation in the flux footprint and the strong curvature of a cubic wind-dependent function for the transfer velocity provides the best fit to the data. Additional data using the measured O 2 flux and an indirect method (based on the Photosynthetic Quotient) to estimate oxygen concentration in water, support the stronger wind dependence for the transfer velocity of O 2 compared to CO 2 . [ABSTRACT FROM AUTHOR]

Highlights: [•] The dynamic response from passing trains at high speed is studied for a short span soil–steel composite bridge. [•] Soil material damping properties are estimated through analysis of the field measurements. [•] Both 2D and 3D continuum models are compared with the measured response. [•] The 3D-model enables estimation of the load distribution, which is found to increase at higher train speeds. [•] An effective width to be used in 2D analyses is proposed. [Copyright &y& Elsevier]

Abstract: The uptake of atmospheric carbon dioxide (CO2) into the mid-latitudes of the North Atlantic Ocean through the production of wintertime Sub-Tropical Mode Water (STMW) also known as Eighteen Degree Water (EDW) is poorly quantified and constrained. Nonetheless, it has been proposed that the EDW could serve as an important short-term sink of anthropogenic CO2. The objective of the present investigation was to determine sea–air CO2 gas exchange rates and seawater CO2 dynamics during wintertime formation of EDW in the North Atlantic Ocean. During 2006 and 2007, several research cruises were undertaken as part of the CLIMODE project across the northwest Atlantic Ocean with the intent to study the pre-conditioning, formation, and the evolution of EDW. Sea–air CO2 exchange rates were calculated based on measurements of atmospheric pCO2, surface seawater pCO2 and wind speed with positive values denoting a net flux from the surface ocean to the atmosphere. Average sea–air CO2 flux calculated along cruise tracks in the formation region equaled −18±6mmol CO2 m−2 d−1 and −14±9mmol CO2 m−2 d−1 in January of 2006 and March of 2007, respectively. Average sea–air CO2 flux in newly formed outcropping EDW in February and March of 2007 equaled −28±10mmol CO2 m−2 d−1. These estimates exceeded previous flux estimates in this region by 40–185%. The magnitude of CO2 flux was mainly controlled by the observed variability in wind speed and ΔpCO2 with smaller changes owing to variability in sea surface temperature. Small but statistically significant difference (4.1±2.6μmolkg−1) in dissolved inorganic carbon (DIC) was observed in two occurrences of newly formed EDW in February and March of 2007. This difference was explained either by differences in the relative contribution from different water masses involved in the initial formation process of EDW or temporal changes owing to sea–air CO2 exchange (∼25%) and vertical and/or lateral mixing (∼75%) with water masses high in DIC from the cold side of the Gulf Stream and/or from below the permanent thermocline. Based on the present estimate of sea–air CO2 flux in newly formed EDW and a formation rate of 9.3Svy (Sverdrup year=106 m3 s−1 flow sustained for 1 year), CO2 uptake by newly formed EDW may constitute 3–6% of the total North Atlantic CO2 sink. However, advection of surface waters that carry an elevated burden of anthropogenic CO2 that are transported to the formation region and transformed to mode water may contribute additional CO2 to the total net uptake and sequestration of anthropogenic CO2 to the ocean interior. [Copyright &y& Elsevier]

Abstract: During routine inspections of the Söderström Bridge in central Stockholm, one of Sweden’s most important railway bridges, cracks were found in the web of the main steel beams. The finding initiated theoretical studies which showed that the cracks developed mainly due to poorly designed connections of the cross beams and out-of-plane bending of the web. The studies also showed an alarming result regarding the remaining fatigue life of the stringers and the cross beams. However, no cracks or other damage have been found on these components during the inspections. To explore the differences between the theoretical indications and the inspected reality, an extensive monitoring program has been performed. This article describes the monitoring program and the analysis methods used. Some results regarding the remaining fatigue life based on measured and theoretical values are presented. [Copyright &y& Elsevier]

Abstract: Carbonate-rich sediments at shoal to shelf depths (<200m) represent a major CaCO3 reservoir that can rapidly react to the decreasing saturation state of seawater with respect to carbonate minerals, produced by the increasing partial pressure of atmospheric carbon dioxide (pCO2) and “acidification” of ocean waters. Aragonite is usually the most abundant carbonate mineral in these sediments. However, the second most abundant (typically ∼24wt%) carbonate mineral is high Mg-calcite (Mg-calcite) whose solubility can exceed that of aragonite making it the “first responder” to the decreasing saturation state of seawater. For the naturally occurring biogenic Mg-calcites, dissolution experiments have been used to predict their “stoichiometric solubilities” as a function of mol% MgCO3. The only valid relationship that one can provisionally use for the metastable stabilities for Mg-calcite based on composition is that for the synthetically produced phases where metastable equilibrium has been achieved from both under- and over-saturation. Biogenic Mg-calcites exhibit a large offset in solubility from that of abiotic Mg-calcite and can also exhibit a wide range of solubilities for biogenic Mg-calcites of similar Mg content. This indicates that factors other than the Mg content can influence the solubility of these mineral phases. Thus, it is necessary to turn to observations of natural sediments where changes in the saturation state of surrounding waters occur in order to determine their likely responses to the changing saturation state in upper oceanic waters brought on by increasing pCO2. In the present study, we investigate the responses of Mg-calcites to rising pCO2 and “ocean acidification” by means of a simple numerical model based on the experimental range of biogenic Mg-calcite solubilities as a function of Mg content in order to bracket the behavior of the most abundant Mg-calcite phases in the natural environment. In addition, observational data from Bermuda and the Great Bahama Bank are also presented in order to project future responses of these minerals. The numerical simulations suggest that Mg-calcite minerals will respond to rising pCO2 by sequential dissolution according to mineral stability, progressively leading to removal of the more soluble phases until the least soluble phases remain. These results are confirmed by laboratory experiments and observations from Bermuda. As a consequence of continuous increases in atmospheric CO2 from burning of fossil fuels, the average composition of contemporary carbonate sediments could change, i.e., the average Mg content in the sediments may slowly decrease. Furthermore, evidence from the Great Bahama Bank indicates that the amount of abiotic carbonate production is likely to decline as pCO2 continues to rise. [Copyright &y& Elsevier]

Abstract: This paper deals with the dynamic effects on a tied arch railway bridge during train passages. The bridge is located in Ånge municipality in central Sweden. Large vibrations of the hangers were observed during train passages and field measurements have been performed to study the train induced vibrations of the hangers. According to the Palmgren–Miners linear damage rule, there is a great risk of fatigue in the threaded parts of the hangers. The low damping in the hangers has a large influence of the risk of fatigue failure. A 3D finite element model of the bridge has been developed where the dynamic vehicle–bridge interaction was modelled using contact surface formulation with a sprung mass train system. The measured data results are compared with the results from the FE model to give a better understanding of the dynamic behaviour of the bridge. [Copyright &y& Elsevier]

In this paper, the dynamic behavior of four railway bridges with integrated retaining walls, considering the effect of soil–structure interaction (SSI), is investigated both numerically and experimentally. Among these bridges, two are single-span, and the remaining two are three-span. Each bridge is equipped with numerous accelerometers and is excited by a hydraulic actuator across various frequencies. Full 3D solid Finite Element (FE) models incorporating the railway bridges and surrounding soils are developed and calibrated using the Frequency Response Functions (FRFs) from each accelerometer. Furthermore, simplified 3D solid and 2D beam models are created for each railway bridge, incorporating springs and dashpots to account for the effect of surrounding soils. The values for these springs and dashpots are obtained from simple equations, except for the impact of the backfill soil in the simplified 2D beam models, which are derived from the impedance functions of the soil medium. The performance of these simplified models is then compared to the calibrated 3D models in terms of modal properties of the first bending mode and the maximum acceleration response during high-speed train passages. The results indicate that the simplified models closely align with the calibrated models in terms of modal properties and high-speed train passage response and can be used as simple and efficient alternatives for practical usage in bridge design. • Experimental analysis of four railway bridges using a hydraulic actuator. • 3D model calibration of each railway bridge and the surrounding soils using forced vibration experiments. • Simplified 3D and 2D modeling techniques of railway bridges, including the SSI, using springs and dashpots. • High-speed train passage analysis of different modeling alternatives. [ABSTRACT FROM AUTHOR]

From observations in a High Arctic valley and ice-free fjord in Svalbard during March and April 2013 we show that, while some caution needs to be applied, ordinary slow-response instruments placed over a snow-water-snow surface can be effectively used as a proxy for more sophisticated measuring techniques at complex sites such as leads or a polynyas. The turbulent fluxes of momentum, sensible and latent heat were measured at three locations with a snow-water-snow fetch. At the snow site upwind of the water, the stability was generally stable, the momentum flux small, and the sensible heat flux positive. Over the water however, the internal boundary layer that was formed gave on average an increased vertical gradient in wind speed, temperature, and humidity and turbulent heat fluxes exceeding 400 W m−2. At the snow surface downwind of the water, the conditions were highly variable and all the fluxes were, on average, of very small magnitude. That the behaviour of the internal boundary layers can be highly variable is demonstrated through four case studies. This phenomenon is likely to increase in occurrence with a changing climate. [ABSTRACT FROM AUTHOR]

The assessment of running safety of railway bridges is conditioned by the Eurocode EN 1990 A2 by limiting vertical deck acceleration. On ballastless track bridges, this value is 5 m/s 2. The background for this value is not clear, and it is believed that it originates in the application of an arbitrary safety factor of 2 on accelerations around 1 g to avoid loss of wheel–rail contact. However, studies show that the level of acceleration may not be directly related to the occurrence of derailment. In this work, this idea is expanded by assessing both vertical and lateral dynamics, comparing acceleration values with the Unloading and Nadal derailment criteria. The parametric study is comprised of a set of five representative single-track slab bridges with spans between 10 m and 30 m with two levels of track irregularities, corresponding to a well-maintained track and an Alert limit situation. A three-dimensional articulated FE model based on the load properties of the EN 1991-2 High-Speed Load Model A is presented, crossing the bridges at running speeds from 150 km/h to 400 km/h. Despite the complexity of the models, a large amount (1461) of full 3D train–track–bridge interaction dynamic analyses are performed, to produce a data set representative of the phenomenon. Results show a weak correlation between the criteria and deck acceleration (maximum r 2 of 0.47 for Unloading and 0.15 for Nadal). Additionally, track quality is shown to be a more conditioning factor for derailment when compared to resonance. This work contributes to discussing the thesis of using deck acceleration as an indicator of running safety, considering lateral dynamics. • The study gives a critical view of the Eurocode's vertical deck acceleration limit. • An articulated 3D Finite Element model of the EN1991-2 HSLM is used. • Deck acceleration values above the limit do not correspond to derailment criteria. • Running safety is more conditioned by track quality than by bridge resonance. [ABSTRACT FROM AUTHOR]

An abstract of the conference paper "FourFlow - open source code software for quantification and visualization of time-resolved three-directional phase contrast magnetic resonance velocity mapping," by Einar Heiberg and colleagues is presented.

This paper is devoted to identify the effect of soil-structure interaction on the dynamic response of a portal frame railway bridge. The study aims to validate the accuracy of numerical models in evaluating the dynamic stiffness and modal properties of the bridge–soil system. To achieve this aim, a controlled vibration test has been performed on a full-scale portal frame bridge to determine the modal properties of the system through measuring Frequency Response Functions. The results of the dynamic test provide reference data for FE model calibration as well as valuable information about the dynamic behavior of this type of bridges. Using the experimental data, an FRF-based model updating procedure was used to calibrate a full 3D solid model involving the entire bridge-track-soil system. Both measured and computed responses identify the substantial contribution of the surrounding soil on the global damping of the system and highlight the importance of the soil–structure interaction on the dynamic response of this type of bridges. The identified modal damping ratio corresponding to the fundamental bending mode of the studied bridge was nearly 5 times higher than the recommended design values. A simplified model for the surrounding soil was also proposed in order to attain a less complicated model appropriate for practical design purposes. [ABSTRACT FROM AUTHOR]

Abstract: Epochs of changing atmospheric CO2 and seawater CO2–carbonic acid system chemistry and acidification have occurred during the Phanerozoic at various time scales. On the longer geologic time scale, as sea level rose and fell and continental free board decreased and increased, respectively, the riverine fluxes of Ca, Mg, DIC, and total alkalinity to the coastal ocean varied and helped regulate the C chemistry of seawater, but nevertheless there were major epochs of ocean acidification (OA). On the shorter glacial–interglacial time scale from the Last Glacial Maximum (LGM) to late preindustrial time, riverine fluxes of DIC, total alkalinity, and N and P nutrients increased and along with rising sea level, atmospheric PCO2 and temperature led, among other changes, to a slightly deceasing pH of coastal and open ocean waters, and to increasing net ecosystem calcification and decreasing net heterotrophy in coastal ocean waters. From late preindustrial time to the present and projected into the 21st century, human activities, such as fossil fuel and land-use emissions of CO2 to the atmosphere, increasing application of N and P nutrient subsidies and combustion N to the landscape, and sewage discharges of C, N, P have led, and will continue to lead, to significant modifications of coastal ocean waters. The changes include a rapid decline in pH and carbonate saturation state (modern problem of ocean acidification), a shift toward dissolution of carbonate substrates exceeding production, potentially leading to the “demise” of the coral reefs, reversal of the direction of the sea-to-air flux of CO2 and enhanced biological production and burial of organic C, a small sink of anthropogenic CO2, accompanied by a continuous trend toward increasing autotrophy in coastal waters. [Copyright &y& Elsevier]

Background: Venous thrombosis (VT) in children is often associated with a central venous catheter (CVC). We aimed to determine the incidence of VT associated with percutaneous non-tunnelled CVCs in a general paediatric population, and to identify risk factors for VT in this cohort.Methods: Observational, prospective study enrolling consecutive patients at a tertiary multi-disciplinary paediatric hospital. A total of 211 percutaneous, non-tunnelled CVCs were analysed. Data regarding potential risk factors for CVC-related VT were collected. Compression ultrasonography with colour Doppler was used to diagnose VT.Results: Overall, 30.3% of children developed CVC-related VT, with an incidence rate of 29.6 (confidence interval, 22.5-36.9) cases/1000 CVC days. Upper body CVC location, multiple lumen CVCs, and male gender were independent risk factors for VT in multivariate analysis. All upper body VTs were in the internal jugular vein (IJV). The occurrence of CVC-related VT did not affect length of paediatric ICU or hospital stay. In patients with VT, femoral CVCs, young age, paediatric ICU admission, and a ratio of CVC/vein diameter >0.33 were associated with VT being symptomatic, occlusive, or both. IJV VT was often asymptomatic and non-occlusive.Conclusions: Paediatric non-tunnelled CVCs are frequently complicated by VT. Avoiding IJV CVCs and multiple lumen catheters could potentially reduce the overall risk of VT. However, IJV VT was more likely to be smaller and asymptomatic compared with femoral vein VT. More data are needed on the risk of complications from smaller, asymptomatic VT compared with the group of VT with symptoms or vein occlusion. Femoral vein CVCs and CVC/vein diameter >0.33 could be modifiable risk factors for VT with larger thrombotic mass.Clinical Trial Registration: ACTRN12615000442505. [ABSTRACT FROM AUTHOR]

Coastal populations and hazards are escalating simultaneously, leading to an increased importance of coastal ocean observations. Many well-established observational techniques are expensive, require complex technical training, and offer little to no public engagement. Smartfin, an oceanographic sensor–equipped surfboard fin and citizen science program, was designed to alleviate these issues. Smartfins are typically used by surfers and paddlers in surf zone and nearshore regions where they can help fill gaps between other observational assets. Smartfin user groups can provide data-rich time-series in confined regions. Smartfin comprises temperature, motion, and wet/dry sensing, GPS location, and cellular data transmission capabilities for the near-real-time monitoring of coastal physics and environmental parameters. Smartfin's temperature sensor has an accuracy of 0.05 °C relative to a calibrated Sea-Bird temperature sensor. Data products for quantifying ocean physics from the motion sensor and additional sensors for water quality monitoring are in development. Over 300 Smartfins have been distributed around the world and have been in use for up to five years. The technology has been proven to be a useful scientific research tool in the coastal ocean—especially for observing spatiotemporal variability, validating remotely sensed data, and characterizing surface water depth profiles when combined with other tools—and the project has yielded promising results in terms of formal and informal education and community engagement in coastal health issues with broad international reach. In this article, we describe the technology, the citizen science project design, and the results in terms of natural and social science analyses. We also discuss progress toward our outreach, education, and scientific goals. [Display omitted] • Smartfin is an IoT, oceanographic sensor-equipped surfboard fin for citizen science. • Over 300 Smartfins have been distributed since 2016. • Roughly 2800 h of coastal data have been collected by participants. • Smartfin data are useful for coastal physics and remote sensing analyses. • Education, outreach, and community are central to project's mission. [ABSTRACT FROM AUTHOR]

• Establish track transition models by combining DEM with FDM. • Compared dynamic performances of different types of track transitions. • Effect of the transition section parameters on dynamic performance of track transitions. • The two-part transition section has better dynamic performance. • The inverted trapezoid transition section has better performance than the trapezoid transition section. To analyze the mesodynamic and macrodynamic performance of the track transitions more precisely, a bridge-embankment transition model has been established by combining the discrete element method (DEM) with the finite difference method (FDM). In this model, the DEM is utilized to model sleepers and ballast particles with complex shape, and the FDM is applied to simulate the abutment, transition section and embankment. The DEM/FDM coupled model is then achieved by exchanging displacements, velocities, and contact forces at the interface. Afterwards, the influence of the transition section parameters and transition forms on dynamic behaviour of the track-substructure system is studied under measured rail seat load. The numerical simulations indicate that the increase of the transition section elastic modulus, decrease of the backfill slope values and the transition form of trapezoid backfill following by inverted trapezoid backfill can provide a better displacement gradient between the abutment and the embankment. Additionally, the results show that the inverted trapezoid transition form can provide a better transition of the track dynamic performance than the trapezoid transition form and the embankment soil over the wedge-shape backfill has the tendency to propagate along the slope toward the embankment section under the moving train load for the trapezoid transition form. [ABSTRACT FROM AUTHOR]