Host Cell Egress and Invasion Induce Marked Relocations of Glycolytic Enzymes in Toxoplasma gondii Tachyzoites

Apicomplexan parasites are dependent on an F-actin and myosin-based motility system for their invasion into and escape from animal host cells, as well as for their general motility. In Toxoplasma gondii and Plasmodium species, the actin filaments and myosin motor required for this process are located in a narrow space between the parasite plasma membrane and the underlying inner membrane complex, a set of flattened cisternae that covers most the cytoplasmic face of the plasma membrane. Here we show that the energy required for Toxoplasma motility is derived mostly, if not entirely, from glycolysis and lactic acid production. We also demonstrate that the glycolytic enzymes of Toxoplasma tachyzoites undergo a striking relocation from the parasites' cytoplasm to their pellicles upon Toxoplasma egress from host cells. Specifically, it appears that the glycolytic enzymes are translocated to the cytoplasmic face of the inner membrane complex as well as to the space between the plasma membrane and inner membrane complex. The glycolytic enzymes remain pellicle-associated during extended incubations of parasites in the extracellular milieu and do not revert to a cytoplasmic location until well after parasites have completed invasion of new host cells. Translocation of glycolytic enzymes to and from the Toxoplasma pellicle appears to occur in response to changes in extracellular [K+] experienced during egress and invasion, a signal that requires changes of [Ca2+]c in the parasite during egress. Enzyme translocation is, however, not dependent on either F-actin or intact microtubules. Our observations indicate that Toxoplasma gondii is capable of relocating its main source of energy between its cytoplasm and pellicle in response to exit from or entry into host cells. We propose that this ability allows Toxoplasma to optimize ATP delivery to those cellular processes that are most critical for survival outside host cells and those required for growth and replication of intracellular parasites

Locality results for certain extensions of theories with bridging functions

Abstract. We study possibilities of reasoning about extensions of base theories with functions which satisfy certain recursion (or homomorphism) properties. Our focus is on emphasizing possibilities of hierarchical and modular reasoning in such extensions and combinations thereof. We present practical applications in verification and cryptography.

On Deciding Functional Lists with Sublist Sets

Abstract. Motivated by the problem of deciding verification conditions for the verification of functional programs, we present new decision procedures for automated reasoning about functional lists. We first show how to decide in NP the satisfiability problem for logical constraints containing equality, constructor, selectors, as well as the transitive sublist relation. We then extend this class of constraints with operators to compute the set of all sublists, and the set of objects stored in a list. Finally, we support constraints on sizes of sets, which gives us the ability to compute list length as well as the number of distinct list elements. We show that the extended theory is reducible to the theory of sets with linear cardinality constraints, and therefore still in NP. This reduction enables us to combine our theory with other decidable theories that impose constraints on sets of objects, which further increases the potential of our decidability result in verification of functional and imperative software.

Optimization of Combined Casing Treatment Structure Applied in a Transonic Axial Compressor Based on Surrogate Model

For modern high load compressors, an excellent stability-enhancing capability by casing treatment (CT) is desirable. However, it is very time consuming to accomplish effective CT design. In this study, a new combined CT structure composed of axial skewed slots and end-wall injection, was proposed to be installed in transonic axial compressors to improve the overall performance. Considering the high computation cost for CFD simulation of the flow field in transonic compressor, a Gaussian Process Regression (GPR) surrogate model combined with Latin hypercube sampling, was utilized to predict compressor performance. For optimization process, a multi-objective evolutionary algorithm (NSGA-Ⅱ) was adopted to obtain the Pareto-optimal front. The main geometric parameters of the slot and the mass-flow rate of injection were selected as design parameters, with the peak efficiency and pressure ratio being two objectives. The results indicated that the surrogate model works well in capturing the key features of the concerning target and accelerating the optimization process. The optimal scheme of the combined CT was found able to increase stall margin (SM) by 19.5% with low efficiency penalty, showing a better performance than the reference combined casing treatment (CCT) scheme. What’s more, the analysis results of entropy generation showed that the superior effect of optimized scheme (OPT) can be attributed to the improvement of exchange flow in slots and the decreased loss in the whole passage

Automatic verification of parametric specifications with complex topologies

The focus of this paper is on reducing the complexity in verification by exploiting modularity at various levels: in specification, in verification, and structurally. For specifications, we use the modular language CSP-OZ-DC, which allows us to decouple verification tasks concerning data from those concerning durations. At the verification level, we exploit modularity in theorem proving for rich data structures and use this for invariant checking. At the structural level, we analyze possibilities for modular verification of systems consisting of various components which interact. We illustrate these ideas by automatically verifying safety properties of a case study from the European Train Control System standard, which extends previous examples by comprising a complex track topology with lists of track segments and trains with different routes

Numerical Investigation of Configurations with Optimum Swirl Recovery for Propeller Propulsion Systems

This paper addresses the design of swirl recovery vanes for propeller propulsion in tractor configuration at cruise conditions using numerical tools.Amultifidelity optimization framework is formulated for the design purpose, which exploits low-fidelity potential flow-based analysis results as input for high-fidelity Euler equation-based simulations. Furthermore, a model alignment procedure between low- and high-fidelity models is established based on a shapepreserving response prediction algorithm. Two cases of swirl recovery are examined. The first is the swirl recovery by the trailing wing, which leads to a reduction of the lift-induced drag. This is achieved by the optimization of the wing twist distribution. The second case is swirl recovery by a set of stationary vanes, which leads to production of additional thrust. In the latter case, four configurations are evaluated by locating the vanes at different azimuthal and axial positions relative to the wing. An optimum configuration is identified where the vanes are positioned on the blade-downgoing side downstream of the wing. For the configuration and conditions examined, the wing twist optimization reduces the induced drag by 3.9 counts (5.9% of wing-induced drag), whereas the optimized 4-bladed SRVs lead to an induced-drag reduction of 6.1 counts (9.2% of wing-induced drag).Flight Performance and Propulsio

Numerical investigation of configuration with optimum swirl recovery for propeller propulsion systems

This paper addresses the design of swirl recovery vanes for propeller propulsion in tractor configuration at cruise conditions using numerical tools. A multi-fidelity optimization framework is formulated for the design purpose, which exploits low-fidelity potential flow-based analysis results as input for high-fidelity Euler equation-based simulations. Furthermore, a model alignment procedure between low-and high-fidelity models is established based on the shape-preserving response prediction algorithm. Two cases of swirl recovery are examined, i.e. swirl recovery by the trailing wing which leads to a reduction of the lift-induced drag, and swirl recovery by a set of stationary vanes (SRVs) located inside the propeller slipstream which leads to production of additional thrust. In the first case, the optimization of the wing circulation distribution is achieved by twist optimization. The resulting reduction in induced drag is 5.9% out of 66.1 counts at the design cruise condition of CL= 0.5. In the case of the SRV design, four configurations are evaluated by locating the vanes at different azimuthal and axial positions relative to the wing. The interactions between SRVs and wing are discussed and an optimum configuration is identified, where the vanes are positioned on the blade-downgoing side downstream of the wing. In this configuration, the wake and tip vortices of the vanes have negligible effect on the wing circulation distribution and consequently introduce no extra drag. With a blade count of 4, the total system drag has decreased by 6.1 counts, which is equivalent to 2.4% of propeller thrust.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.Flight Performance and Propulsio

Aerodynamic Loads on an Aft-Mounted Propeller Induced by the Wing Wake

This paper presents an experimental and numerical study of the aerodynamic in-plane and out-of-plane loads of a propeller which are induced by the wake of an upstream wing impinging on the lower half of the propeller disk. A propeller was installed behind a wing model in a low-speed wind-tunnel and measurements were taken with an external balance and a rotating shaft balance to determine the aerodynamic characteristics of the wing and propeller. The installation of the wing shows negligible changes in propeller thrust coefficient at low advance ratios, while at medium thrust conditions (C T ≈ 0.3), the wing shows a small increase in propeller thrust in the order of 1%. The installation of the propeller aft of the wing shows a change on propeller efficiency ranging from ∆η p =–0.01 to +0.04. The location of the wake impingement at the propeller plane is shown to play an important factor for the time averaged and unsteady propeller loads. The radial location where the largest change in load occurs due to wake impingement, coincides with the location of highest propeller loading. A simplified and computationally efficient method is presented for estimation of these unsteady propeller loads in non-uniform inflow. The method shows good agreement for the integral unsteady blade thrust and integral propeller for different wake impingement locations. Accepted Author ManuscriptFlight Performance and Propulsio