Surface glycans regulate Salmonella infection-dependent directional switch in macrophage galvanotaxis via a dispensable role of NanH

Salmonella invades and disrupts gut epithelium integrity, creating an infection-generated electric field that can drive directional migration of macrophages, a process called galvanotaxis. Phagocytosis of bacteria reverses the direction of macrophage galvanotaxis, implicating a bioelectrical mechanism to initiate life-threatening disseminations. The force that drives direction reversal of macrophage galvanotaxis is not understood. One hypothesis is that Salmonella can alter the electrical properties of the macrophages by modifying host cell surface glycan composition, which is supported by the fact that cleavage of surface-exposed sialic acids with a bacterial neuraminidase severely impairs macrophage galvanotaxis, as well as phagocytosis. Here, we utilize N-glycan profiling by nanoLC-chip QTOF mass cytometry to characterize the bacterial neuraminidase-associated compositional shift of the macrophage glycocalyx, which revealed a decrease in sialylated and an increase in fucosylated and high mannose structures. The Salmonella nanH gene, encoding a putative neuraminidase, is required for invasion and internalization in a human colonic epithelial cell infection model. To determine whether NanH is required for the Salmonella infection-dependent direction reversal, we constructed and characterized a nanH deletion mutant and found that NanH is partially required for Salmonella infection in primary murine macrophages. However, compared to wild type Salmonella , infection with the nanH mutant only marginally reduced the cathode-oriented macrophage galvonotaxis, without canceling direction reversal. Together, these findings strongly suggest that while neuraminidase-mediated N-glycan modification impaired both macrophage phagocytosis and galvanotaxis, yet to be defined mechanisms other than NanH may play a more important role in bioelectrical control of macrophage trafficking, which potentially triggers dissemination.

Lexicographically Maximum Contraflow Problem with Vertex Capacities

The contraflow approach has been extensively considered in the literature for modeling evacuations and has been claimed, due to its lane-direction-reversal capability, as an efficient idea to speed up the evacuation process. This paper considers the contraflow evacuation model on network with prioritized capacitated vertices that allows evacuees to be held at intermediate spots too, respecting their capacities and priority order. In particular, it studies the maximum flow evacuation planning problem and proposes polynomial and pseudo-polynomial time solution algorithms for static network and dynamic multinetwork, respectively. A real dataset of Kathmandu road network with evacuation spaces is considered to implement the algorithm designed for dynamic multinetwork and to observe its computational performance.

Quantum Pumping with Adiabatically Modulated Barriers in Three-Band Pseudospin-1 Dirac–Weyl Systems

In this work, pumped currents of the adiabatically-driven double-barrier structure based on the pseudospin-1 Dirac–Weyl fermions are studied. As a result of the three-band dispersion and hence the unique properties of pseudospin-1 Dirac–Weyl quasiparticles, sharp current-direction reversal is found at certain parameter settings especially at the Dirac point of the band structure, where apexes of the two cones touch at the flat band. Such a behavior can be interpreted consistently by the Berry phase of the scattering matrix and the classical turnstile mechanism.

Inchworm bipedal nanowalker

A DNA bipedal walker shows stride-controlled gait switch and direction reversal.

A Symmetry Hidden at The Center of Quantum Mathematics Causes a Disconnect Between Quantum Math and Quantum Mechanics

Although quantum mathematics is the most successful science ever, that does not mean we live in the universe described by quantum mechanics. This article is entirely based on symmetry. Two symmetrical universes could have exactly the same mathematics, but differ in other respects. The motivation for seeking symmetry inside quantum mathematics is that the QM picture of nature is bizarre. Richard Feynman says no one can understand it. We propose that the quantum world is not bizarre. QM portrays the wrong universe: the symmetrical one, not the one we inhabit. If quantum waves travel in the opposite direction as what is expected, then we would have the same math but a different universe, one that is recognizable and familiar. Wave equations are symmetrical with respect to time reversal. This means they are symmetrical with respect to wave direction reversal (with time going forwards). This wave equation symmetry is the basis of the symmetry of two models of the universe, only one of which is congruent with the universe we inhabit.

Sliding wear mechanism of ductile materials – Effect of sliding direction reversal

The work presented in this paper tries to shed more light on the mechanism by which ductile surfaces fail and leave the contact surface during loaded pure sliding contact. An extensive experimental program was designed aimed at exploring the role of plastic shear strain accumulation in surface failure. Reversing the direction of strain during testing was the main variable which was facilitated by reversing the sliding direction. Changes in structure deformation morphology and accumulated plastic strain were analyzed. The effect of different sliding direction reversal regimes during testing, compared to unidirectional sliding to the same sliding distance, was thoroughly investigated. Results came to support that plastic strain accumulation is responsible for contact surface failure and, as a result, material loss from the ductile surface during sliding. It was evident, under the test conditions used, that reversing the sliding direction at different predefined sliding distances has resulted in delaying surface failure, resulting in lower wear loss compared to that found under unidirectional sliding. Multiple strain direction reversals resulted in higher beneficial effect in delaying failure. Furthermore, the earlier the sliding reversal is carried out, the better its effect of delaying failure. Findings have been explained in terms of plastic strain accumulation that leads to failure of the surface layer after reaching a certain strain to failure limit.

Role of impact angle reversal on impact wear of mild steel

Impact wear of mild steel has been studied in light of impact angle reversal. An in-house built, specially designed test rig has been used to facilitate test conditions, including impact angle reversal. Metallographic examination and scanning electron microscopy were used to analyze the morphology of impact surfaces. Results showed lower impact wear under condition involving impact angle reversal for the whole range of impact angles. Furthermore, multiple impact direction reversal showed significant impact wear reduction. Behavior has been explained in terms of failure due to plastic deformation accumulation.

Modified transformation laws of coordinates and composition of velocities

A new transformation law of coordinates is determined, which allows the inclusion of complex velocity vectors. It is found that in an isotropic universe which is filled with matter throughout, each frame can have references for its position of rest or of motion in a localized domain wherein a frame at rest does not change its position with time relative to surroundings. However, in the system, the moving frame sees only a reflection of its own motion in the rest-frame to appear it moving in antipodal direction. It is therefore, the relative motion cannot be said to be a just direction reversal with two real velocities having a single magnitude common between them; however, it is a synthesis of both real and imaginary motions. The proposed transformation laws are similar to that of Lorentz under which vector quantities be in cross product or in dot product remain invariant such as Maxwell equations. However, inherent scalar quantities such as mass, time etc. vary to distinguish rest-frame from the moving one. It is seen that the physical processes are exactly the same as Einstein predicted but without reciprocity effects and thus provide a justification of quantization of red-shift and particle decay. These considerations are useful in understanding the intricacies of the micro world such as short-lived particle, antimatter, subatomic particles, gamma rays, gamma-ray burst (GRBs), cosmic rays, dark matter, and asymmetry of Doppler’s shifting images.