Climate change effects on phytoplankton depend on cell size and food web structure

We investigated the effects of warming on a natural phytoplankton community from the Baltic Sea, based on six mesocosm experiments conducted 2005–2009. We focused on differences in the dynamics of three phytoplankton size groups which are grazed to a variable extent by different zooplankton groups. While small-sized algae were mostly grazer-controlled, light and nutrient availability largely determined the growth of medium- and large-sized algae. Thus, the latter groups dominated at increased light levels. Warming increased mesozooplankton grazing on medium-sized algae, reducing their biomass. The biomass of small-sized algae was not affected by temperature, probably due to an interplay between indirect effects spreading through the food web. Thus, under the higher temperature and lower light levels anticipated for the next decades in the southern Baltic Sea, a higher share of smaller phytoplankton is expected. We conclude that considering the size structure of the phytoplankton community strongly improves the reliability of projections of climate change effects

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Foam Propagation at Low Superficial Velocity: Implications for Long-Distance Foam Propagation

Since the 1980s experimental and field studies have found anomalously slow propagation of foam that cannot be explained by surfactant adsorption. Friedmann et al. (1994) conducted foam-propagation experiments in a coneshaped sandpack and concluded that foam, once formed in the narrow inlet, was unable to propagate at all at lower superficial velocities towards the wider outlet. They hence concluded that long-distance foam propagation in radial flow from an injection well is in doubt. Ashoori et al. (2012) provide a theoretical explanation for slower or non-propagation of foam at decreasing superficial velocity. Their explanation connects foam propagation to the minimum velocity or pressure gradient required for foam generation in homogeneous porous media (Gauglitz et al., 2002). The conditions for propagation of foam are less demanding than those for creation of new foam. However, there still can be a minimum superficial velocity necessary for propagation of foam, except that it could be significantly smaller than the minimum velocity for foam generation from an initial state of no-foam. At even lower superficial velocity, theory (Kam and Rossen, 2003) predicts a collapse of foam. In this study, we extend the experimental approach of Friedmann et al. in the context of the theory of Ashoori et al. We use a cylindrical core with stepwise increasing diameters such that the superficial velocity in the outlet section is 1/16 of that in the inlet. N2 foam is created and stabilized by an alpha olefin sulfonate surfactant. Previously (Yu et al., 2019), we mapped the conditions for foam generation in a Bentheimer sandstone core as a function of total superficial velocity, surfactant concentration and injected gas fraction (foam quality). In this study, we extend the map to include the conditions for propagation of foam, after its creation in the narrow inlet section at greater superficial velocity. Thereafter, by reducing superficial velocity, we map the conditions for foam collapse. Our results suggest that the minimum superficial velocities for foam generation, propagation and maintenance increase with increasing foam quality and decreasing surfactant concentration, in agreement with theory. The minimum velocity for propagation of foam is much less than that for foam generation, and that for foam maintenance is less than that for propagation. The implications of our lab results for field application of foam are discussed.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Petroleum Engineerin

Nanoparticle Stabilized Foam in Carbonate and Sandstone Reservoirs

Foam flooding as a mechanism to enhance oil recovery has been intensively studied and is the subject of multiple research groups. However, limited stability of surfactant-generated foam in presence of oil and low chemical stability of surfactants in the high temperature and high salinity of an oil reservoir are among the reasons for foam EOR not being widely applied in the field. Unlike surfactants, nanoparticles, which are shown to be effective in stabilizing bulk foam, are chemically stable in a wide range of physicochemical conditions. Recent studies suggest that synthesized nanoparticles with altered surface properties can aid foam generation and increase foam stability in porous media. In this paper, the focus lies on a silica-based nanoparticle that is available in large quantities and can be processed economically without separate surface treatment, which gives it the potential to become a practical solution in the field. The research is primarily conducted by performing core-flooding experiments under varying conditions to quantitatively assess and compare the potential of the nanoparticle-enhanced foam. Two types of reservoir rocks have been investigated: sandstone and carbonate rocks. It is observed that by adding even low concentrations of nanoparticles to a near-CMC surfactant solution, the foam viscosity considerably increases.Geoscience & EngineeringCivil Engineering and Geoscience

Convective instabilities in a laminar shock-wave/boundary-layer interaction

Linear stability analyses are performed to study the dynamics of linear convective instability mechanisms in a laminar shock-wave/boundary-layer interaction at Mach 1.7. In order to account for all two-dimensional gradients elliptically, we introduce perturbations into an initial-value problem that are found as solutions to an eigenvalue problem formulated in a moving frame of reference. We demonstrate that this methodology provides results that are independent of the numerical setup, frame speed, and type of eigensolutions used as initial conditions. The obtained time-integrated wave packets are then Fourier-transformed to recover individual-frequency amplification curves. This allows us to determine the dominant spanwise wavenumber and frequency yielding the largest amplification of perturbations in the shock-induced recirculation bubble. By decomposing the temporal wave-packet growth rate into the physical energy-production processes, we provide an in-depth characterization of the convective instability mechanisms in the shock-wave/boundary-layer interaction. For the particular case studied, the largest growth rate is achieved in the near-vicinity of the bubble apex due to the wall-normal (productive) and streamwise (destructive) Reynolds-stress energy-production terms. We also observe that the Reynolds heat-flux effects are similar but contribute to a smaller extent. Funding Information: The authors acknowledge the funding provided to Sébastien E.M. Niessen by the Fonds National de la Recherche Scientifique de Belgique (F.R.S.-FNRS) under Grant No. FC27285 and the computational resources provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the F.R.S.-FNRS under Grant No. 2.5020.11 and by the Walloon Region (Belgium). Publisher Copyright: © 2023 Author(s).Aerodynamic

A 210nW BJT-based Temperature Sensor with an Inaccuracy of ±0.15°C (3s) from -15°C to 85°C

This paper presents a 210nW BJT-based temperature sensor that achieves an inaccuracy of ±0.15°C (3s) from -15°C to 85°C. A dual-mode front-end (FE), which combines a bias circuit and a BJT core, halves the power needed to generate well-defined CTAT (VBE) and PTAT (?VBE) voltages. The use of a tracking ?S ADC reduces FE signal swing and further reduces system power consumption. In a 180-nm BCD process, the prototype achieves a 15mK resolution in 50ms conversion time, translating into a state-of-the-art FoM of 2.3pJK2. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic

TourExplain: A Crowdsourcing Pipeline for Generating Explanations for Groups of Tourists

When a group is traveling together it is challenging to recommendan itinerary consisting of several points of interest (POIs). Thepreferences of individual group members often diverge, but it isimportant to keep everyone in the group satisfied during the entiretrip. We propose a method to consider the preferences of all thepeople in the group. Building on this method, we design expla-nations for groups of people, to help them reach a consensus forplaces to visit. However, one open question is how to best formu-late explanations for such sequences. In this paper, we introduceTourExplain, an automated crowdsourcing pipeline to generate andevaluate explanations for groups with the aim of improving ourinitial proposed explanations by relying on the wisdom of crowds.Accepted author manuscriptWeb Information System

Fall-off test analysis and transient pressure behavior in foam flooding

Gas injection projects often suffer from poor volumetric sweep because under reservoir conditions the density and viscosity differences between the gas and the in-situ oil leads to override and bypassing of much of the oil in place. Foam has been suggested as a potential solution to this shortcoming and has shown success in some of the field applications. In the field scale foam can reduce the gas mobility, fight against gravity by inducing excess viscous forces and reduce the gas-oil ratio in the producer. Nevertheless, foam propagation in the reservoir, with low fluid velocities, and survival of foam in the path from injector to producer are among major uncertainties in foam projects. This necessitates the design of surveillance plans to monitor foam rheology and its propagation in porous media. Usually foam generation inside a porous medium is indirectly inferred from the pressure response; once foam is generated in the reservoir the pressure increases. Foam frequently exhibits non-Newtonian (shearthinning) behaviour, as it is propagated through the porous medium, which can influence the pressure transient test behaviour. This paper studies different well testing interpretation and pressure behaviour of foam flow in a homogenous reservoir. Local-equilibrium or implicit-texture foam model (that of STARS) are used to model the foam behaviour in porous media. Pressure fall-off test behaviour presented in this paper is new for foam injection. The flow regimes including inclined radial flow, radial flow, transient section, and reservoir boundary are discussed. A method which uses a pressure and a pressure derivative plot is developed for foam injection so that the mobility changes, flow behaviour index, location of foam front, reservoir parameters and reservoir boundary can be estimated. The results of this study can be used to analyse data from injection well, where monitoring of the generation, stability and distribution of foam is a key factor in the success of a foam field project. This paper discuss the dependency of the results on foam-model parameters, which indicates that by using pressure transient data one can obtain the foam model parameter.Geoscience & EngineeringCivil Engineering and Geoscience