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Flagellates are key components of aquatic microbial food webs. Their flagella propel the cell through the water and/or generate a feeding current from which bacterial prey is harvested, but the activity of the flagella also disturbs the ambient water, thereby attracting the flagellate's flow-sensing predators. Here we use computational fluid dynamics to explore the optimality and fluid dynamics of the diverse arrangements, beat patterns, and external morphologies of flagella found among free-living flagellates in light of the fundamental propulsion–foraging–predation-risk trade-off. We examine 5-µm-sized representative model organisms with different resource acquisition modes: autotrophs relying on photosynthesis and uptake of nutrient molecules, phagotrophs that feed on bacteria, and mixotrophs that employ both strategies. For all types, the transport of inorganic molecules is diffusion dominated, and the flagellum in autotrophic species therefore mainly serves propulsion purposes. Flagellates with a single, naked flagellum found among nonforaging swarmer stages have a waveform (less than one wave) that is optimized for swimming and stealth but inefficient for feeding. Flagellates with a hairy flagellum typically have many waves, which optimizes swimming and stealth but is suboptimal for foraging, leading to a design trade-off. However, when compared with naked flagella, the presence of hairs allows a very efficient feeding current, making these primarily phagotrophic flagellates the most efficient and dominant bacterivores in the ocean. Autotrophic biflagellates have wave patterns optimized for both propulsion and foraging but conflicting weakly with stealth. Finally, the mixotrophic haptophytes are optimized for foraging, conflicting with both stealth and propulsion. This is largely due to the long, slender filament (haptonema) that improves prey collection but at the cost of stealth and propulsion. We use dimensional analysis to rationalize our findings. We conc

Ocean wave energy has the potential of contributing significantly to the industrial energy production and export, both as a stand alone solution by using wave energy converters (WECs) in wave energy parks, and in combination with offshore wind energy. For comparison the power intensity of wind is 0.4 0.6 kW/m2 , solar is 0.1 0.2 kW/m2 and wave power intensity is about 2 3 kW/m 2 [1, Wave energy converter Crestwing is an attenuator type of WEC with proven technology and simple feasibi lity originated from shipbuilding industry [3]. Although it seems to be a feasible technology it still has many avenues for optimizing efficiency and minimizing costs to drive down levelized cost of electricity. E ffective energy harvesting is only conceiva ble by interpretation of underlying physics and optimization of key parameters of a WEC such as hull shape. For these goals we use state of the art CFD simulation tools based on fifth order Stokes wave theory, overset mesh technique and dynamic fluid body interaction. At the symposium we will present verification and validation of the CFD model relying on existing model tests and use the CFD results to highlight the key components of the Crestwing WEC [4, 5].

In this study, by performing all-atom Non-Equilibrium Molecular Dynamics simulations, we propose a graphene-based thermal nanopump which produces controlled and continuous water flow in nanoslit channels. Upon systematically imposing thermal gradients, a significant net fluid flow towards the lowtemperature zone is measured in all cases. The nanopump produces water flow with average velocities up to 3 m/s. We find that the water flow rates increase due to an enhancement of the wall thermal rippling as higher temperature gradients are imposed. Moreover, vibrational and phonon Density-of-States analyses on graphene reveal that the out-of-plane flexural phonons in graphene are responsible for the net flow production. We notice that lower frequency phonon branches are activated with higher imposed temperature gradients. This study provides the basis for developing a functional thermal pumping system based on sheets of graphene, which is capable to produce continuous water flow in nanofluidic conduits, opening the door to practical exploitation of thermal gradients for fluid transport in integrated nanofluidic devices.

Ocean wave energy has the potential of contributing significantly to the industrial energy production and export, both as a standalone solution by using wave energy converters (WECs) in wave energy parks, and in combination with offshore wind energy. For comparison the power intensity of wind is 0.4 - 0.6 kW/m2, solar is 0.1 - 0.2 kW/m2 and wave power intensity is about 2 - 3 kW/m2 [1, 2]. The wave energy converter Crestwing is an attenuator type of WEC with proven technology and simple feasibility originated from the shipbuilding industry [3]. Although it seems to be a feasible technology it still has many avenues for optimizing efficiency and minimizing costs to drive down levelized cost of electricity. Effective energy harvesting is only conceivable by interpretation of underlying physics and optimization of key parameters of a WEC such as hull shape. For these goals we use state-of-the-art CFD simulation tools based on fifth-order Stokes wave theory, overset mesh technique and dynamic fluid body interaction. At the symposium we will present verification and validation of the CFD model relying on existing model tests and use the CFD results to highlight the key components of the Crestwing WEC [4, 5].

Physician burnout is a systemic problem in health care due to its high prevalence and its negative impact on professional functioning and individual well-being. While unique aspects of the physician role contributing to the development burnout have been investigated recently, it is currently unclear whether burnout manifests differently in physicians compared to the non-physician working population. We conducted an individual symptom analysis of burnout symptoms comparing a large sample of physicians with a non-physician group. In this cross-sectional online study, burnout was assessed with the Maslach Burnout Inventory—General Survey. We matched physicians with non-physicians regarding their age, gender, educational level, occupational status, and total burnout level using a “nearest neighbour matching” procedure. We then conducted a series of between-groups comparisons. Data of 3846 (51.0% women) participants including 641 physicians and 3205 non-physicians were analysed. The most pronounced difference was that physicians were more satisfied with their work performance (medium effect size (r = 0.343). Our findings indicate minor yet significant differences in burnout phenomenology between physicians and non-physicians. This demonstrates unique aspects of physician burnout and implies that such differences should be considered in occupational research among physicians, particularly when developing burnout prevention programs for physicians.

Children with high-risk SHH/TP53-mut and Group 3 medulloblastoma (MB) have a 5-year overall survival of only 40 %. Innovative approaches to enhance survival while preventing adverse effects are urgently needed. We investigated an innovative therapy approach combining irradiation (RT), decitabine (DEC), and abacavir (ABC) in a patient-derived orthotopic SHH/TP53-mut and Group 3 MB mouse model. MB-bearing mice were treated with DEC, ABC and RT. Mouse survival, tumor growth (BLI, MRT) tumor histology (H/E), proliferation (Ki-67), and endothelial (CD31) staining were analyzed. Gene expression was examined by microarray and RT-PCR (Ki-67, VEGF, CD31, CD15, CD133, nestin, CD68, IBA). The RT/DEC/ABC therapy inhibited tumor growth and enhanced mouse survival. Ki-67 decreased in SHH/TP53-mut MBs after RT, DEC, RT/ABC, and RT/DEC/ABC therapy. CD31 was higher in SHH/TP53-mut compared to Group 3 MBs and decreased after RT/DEC/ABC. Microarray analyses showed a therapy-induced downregulation of cell cycle genes. By RT-PCR, no therapy-induced effect on stem cell fraction or immune cell invasion/activation could be shown. We showed for the first time that RT/DEC/ABC therapy improves survival of ortothopic SHH/TP53-mut and Group 3 MB-bearing mice without inducing adverse effects suggesting the potential for an adjuvant application of this multimodal therapy approach in the human clinic.

Ship-to-ship bunkering of liquid fuel, e.g., LNG, outside the port can be a flexible and cost-efficient solution without having to upgrade the infrastructures at the port. The occurrence of fluid resonance in the narrow gap between side-by-side receiving vessel and bunkering vessel under wave actions may greatly influence the dynamic responses of the vessels through hydrodynamic interaction. The proximity of marine structures can generate drastic wave elevation in the narrow gap, which may reduce the operational time window of the bunkering and even risk the safety of the crew. In this paper, the fluid resonance inside the gap between two non-identical ship cross-sections in side-by-side configuration is studied under various wave conditions. The bunkering scenario that a larger cross-section on the upstream is fixed while a small cross-section free to heave in the downstream is considered as more realistic. A numerical wave tank is set up based on the commercial CFD package STAR-CCM+. The unsteady Reynolds averaged Navier-Stokes turbulence model is required to consider viscous dissipation. The volume of fluid method is applied to capture the position of the free surface, and regular waves are generated and absorbed using forcing zones at upstream and downstream boundaries, respectively. The overset meshing technique is employed near the downstream section to enable the heave motion. The heave response of the downstream section and its effect on the linear and nonlinear harmonics of wave elevation and resonant frequency inside the gap are investigated and compared with the fixed-sections scenario. It can be concluded that the heave motion reduces the gap resonance to a large extent by modulating the frequency of wave elevation inside the gap, thus avoiding the occurrence of second-order excitation.

The importance of CFD is increasing in marine hydrodynamics in studying seakeeping and added resistance of ships. While extensive numerical studies have been reported for various ships in head seas in the literature, much fewer CFD studies are found for oblique waves, which in practice is very important in, for instance, estimating required power and maneuverability of ships in realistic sea states. In this paper, the added resistance and motion responses for the KCS container ship in regular waves are studied and validated systematically for two wave headings and six wavelengths using CFD. The ship is free to heave, pitch, and roll. User-defined implementations in the commercial CFD code are made to effectively constrain the surge and yaw. Results of the CFD model are compared with up to three sets of experimental data sets, Potential Flow (PF) and existing CFD results from the literature. In general, the present CFD results show significantly better agreement with the experiments than previously published CFD results. The present study shows that CFD simulations can accurately predict motion responses and added resistance in oblique regular waves. With these results, designers of ship hulls can get an insight of where to focus the optimization work in the pursuit of fuel-efficient vessels.