Varicella zoster virus glycoprotein C increases chemokine-mediated leukocyte migration

Varicella zoster virus (VZV) is a highly prevalent human pathogen that establishes latency in neurons of the peripheral nervous system. Primary infection causes varicella whereas reactivation results in zoster, which is often followed by chronic pain in adults. Following infection of epithelial cells in the respiratory tract, VZV spreads within the host by hijacking leukocytes, including T cells, in the tonsils and other regional lymph nodes, and modifying their activity. In spite of its importance in pathogenesis, the mechanism of dissemination remains poorly understood. Here we addressed the influence of VZV on leukocyte migration and found that the purified recombinant soluble ectodomain of VZV glycoprotein C (rSgC) binds chemokines with high affinity. Functional experiments show that VZV rSgC potentiates chemokine activity, enhancing the migration of monocyte and T cell lines and, most importantly, human tonsillar leukocytes at low chemokine concentrations. Binding and potentiation of chemokine activity occurs through the C-terminal part of gC ectodomain, containing predicted immunoglobulin-like domains. The mechanism of action of VZV rSgC requires interaction with the chemokine and signalling through the chemokine receptor. Finally, we show that VZV viral particles enhance chemokine-dependent T cell migration and that gC is partially required for this activity. We propose that VZV gC activity facilitates the recruitment and subsequent infection of leukocytes and thereby enhances VZV systemic dissemination in humans

Werewolves, cheats, and cultural sensitivity

This paper discusses the design and evaluation of the system MIXER (Moderating Interactions for Cross-Cultural Empathic Relationships), which applies a novel approach to the education of children in cultural sensitivity. MIXER incorporates intelligent affective and interactive characters, including a model of a Theory of Mind mechanism, in a simulated virtual world. We discuss the relevant pedagogical approaches, related work, the underlying mind model used for MIXER agents as well as its innovative interaction interface utilising a tablet computer and a pictorial interaction language. We then consider the evaluation of the system, whether this shows it met its pedagogical objectives, and what can be learned from our results.</p

A comparative reliability analysis of ballistic deployments on binary asteroids

Small body missions can significantly benefit from deploying small landing systems onto the surface of the visited object. Despite the potential benefit that they may bring, deployments of landers in small body environments may entail significant mission design challenges. This paper thus addresses the potential of ballistic landing opportunities in binary asteroid moons from a mission design perspective, particularly focusing on reliability aspects of the trajectories. Two binaries that were previously identified as target bodies in several missions/proposals, Didymos and 1996 FG3, are considered in this paper. The dynamics near them are modeled by means of the Circular Restricted Three Body Problem (CR3BP), which provides a reasonable representation of a standard binary system. Natural landing trajectories that allow both minimum-velocity local-vertical touchdown and deployment from a safe distance are investigated. Coefficient of restitution values are used as a design parameter to compute the first touchdown speeds that ensure sufficient reliability of landing trajectories. A simple reliability index, which is derived via uncertainty ellipsoid from covariance analysis, is introduced to create a global reliability map across the asteroid surfaces. Assuming 3σ deployment errors on the order of 90 m and 2 cm/s, the results show that ballistic landing operations are likely to be successful for larger binary moons if the deployments target near equatorial regions within longitude range 320o–20°. It has also been shown that the deployments to smaller binary moons may require higher accuracy in navigation and deployment systems in their mothership, and/or closer deployment distances

Analysis of natural landing trajectories for passive landers in binary asteroids: A case study for (65803) 1996GT didymos

Binary asteroids are believed to constitute about 15% percent of the near-Earth asteroid (NEA) population. Their abundance and yet-to-be-resolved formation mechanism make them scientifically interesting, but they can also be exploited as a test bed for kinetic impactors, as the Asteroid Impact and Deflection Assessment (AIDA) joint mission proposal suggested. In addition to impactor spacecraft of AIDA, i.e. DART, the observation spacecraft, called Asteroid Impact Mission (AIM) (whose future is now uncertain) is to characterize Didymos, including pre- and post-impact variations. Due to the highly perturbed dynamical environment around asteroids, large, and generally expensive missions are preferred to be operated from a safe distance from target asteroid. Even if advanced remote sensing techniques provide the finest details of the target, surface agents can obtain higher resolution and ground truth data. Lander solutions for small body exploration have already been suggested in various missions/proposals. The most recent example is the AIM proposal, which envisage to deploy MASCOT lander on the surface of Didymoon. Additionally, AIM proposed to carry two CubeSats on board. A team led by Royal Observatory of Belgium (ROB) proposed Asteroid Geophysical Explorer (AGEX) CubeSat to land on Didymoon. CubeSats can be employed much more daringly in small body environments due to their versatile character and low development cost. Nevertheless, they possess only limited AOCS capabilities because of their size, and in most cases they are passive. This research offers novel landing trajectories by exploiting the natural dynamics of binary systems. The framework of Circular Restricted Three-Body Problem is used for this purpose, in which two asteroids orbit each other around their common center of mass, while third body (CubeSat) move under their gravitational field. Landing trajectories are propagated backwards in time; from each latitude-longitude points in densely meshed surface through the low energy gate at L2. A newly developed bisection algorithm ensures to generate the lowest energy trajectory for landing point under given constraints. The results suggest that landing speeds less than 8 cm/s are possible, while coefficient restitutions of over 0.9 for spherical asteroids would ensure a successful landing. Robustness of trajectories is also investigated. Uncertainties in deployment mechanism and GNC errors of mothership are considered. Trajectories that are obtained in backwards time propagation are added pseudo-random errors, then propagated forward to the surface in a Monte Carlo simulation, in which 1000 trajectories are propagated. The deployment altitude is found to be severely degrading the success rate. The GNC velocity errors are also found to be more effective than their position counterparts. The success rate over 99.7% (3) can be achieved, though extra requirements might need to be considered for mothership design

Varicella zoster virus glycoprotein C increases chemokine-mediated leukocyte migration

Varicella zoster virus (VZV) is a highly prevalent human pathogen that establishes latency in neurons of the peripheral nervous system. Primary infection causes varicella whereas reactivation results in zoster, which is often followed by chronic pain in adults. Following infection of epithelial cells in the respiratory tract, VZV spreads within the host by hijacking leukocytes, including T cells, in the tonsils and other regional lymph nodes, and modifying their activity. In spite of its importance in pathogenesis, the mechanism of dissemination remains poorly understood. Here we addressed the influence of VZV on leukocyte migration and found that the purified recombinant soluble ectodomain of VZV glycoprotein C (rSgC) binds chemokines with high affinity. Functional experiments show that VZV rSgC potentiates chemokine activity, enhancing the migration of monocyte and T cell lines and, most importantly, human tonsillar leukocytes at low chemokine concentrations. Binding and potentiation of chemokine activity occurs through the C-terminal part of gC ectodomain, containing predicted immunoglobulin-like domains. The mechanism of action of VZV rSgC requires interaction with the chemokine and signalling through the chemokine receptor. Finally, we show that VZV viral particles enhance chemokine-dependent T cell migration and that gC is partially required for this activity. We propose that VZV gC activity facilitates the recruitment and subsequent infection of leukocytes and thereby enhances VZ

Structure and magnetic properties of the n = 3 Ruddlesden-Popper oxyfluoride La0.5Sr3.5Fe3O7.5F2.6

Ruddlesden–Popper (RP) compounds of the general formula (AX)(ABX3)n with their unique sequence of perovskite-like (ABX3) and rock-salt-like units (AX) promise applications in diverse fields such as catalysis and superconductivity. Fluorination of RP oxides often leads to dramatic changes in the material properties, caused by differences in the atomic and electronic structure. While current research focuses on fluorination of n = 1 type RP oxides (A2BO4), n = 3 RP oxyfluorides have remained elusive. We present the synthesis of the first iron-based n = 3 RP oxyfluoride, La0.5Sr3.5Fe3O7.5F2.6, which was obtained from an oxide precursor by topochemical fluorination with poly(vinylidene fluoride). Joint Rietveld refinements of neutron and powder X-ray diffraction data were used to determine the crystal structure. Best results were obtained in the space group Pbca (No. 61) with a = 5.5374(1) Å, b = 5.5441(1) Å, and c = 29.2541(2) Å. The effect of the aliovalent incorporation of fluoride ions is particularly evident with respect to changes in structure and magnetic properties. The magnetic behavior was studied using field- and temperature-dependent magnetization measurements, Mößbauer spectroscopy, and neutron diffraction. Additional magnetic Bragg reflections observed in the room-temperature neutron data were successfully refined in the space group Pbca (61.1.497 in Opechowski–Guccione notation), indicating a G-type antiferromagnetic ordering with a surprisingly high Néel temperature above 300 K. This strong increase of TN by several hundred Kelvin compared to the parent oxide is particularly remarkable

Structure and Magnetic Properties of the n = 3 Ruddlesden–Popper Oxyfluoride La 0.5 Sr 3.5 Fe 3 O 7.5 F 2.6

Ruddlesden–Popper (RP) compounds of the general formula (AX)(ABX 3 ) n with their unique sequence of perovskite-like (ABX 3 ) and rock-salt-like units (AX) promise applications in diverse fields such as catalysis and superconductivity. Fluorination of RP oxides often leads to dramatic changes in the material properties, caused by differences in the atomic and electronic structure. While current research focuses on fluorination of n = 1 type RP oxides (A 2 BO 4 ), n = 3 RP oxyfluorides have remained elusive. We present the synthesis of the first iron-based n = 3 RP oxyfluoride, La 0.5 Sr 3.5 Fe 3 O 7.5 F 2.6 , which was obtained from an oxide precursor by topochemical fluorination with poly(vinylidene fluoride). Joint Rietveld refinements of neutron and powder X-ray diffraction data were used to determine the crystal structure. Best results were obtained in the space group Pbca (No. 61) with a = 5.5374(1) Å, b = 5.5441(1) Å, and c = 29.2541(2) Å. The effect of the aliovalent incorporation of fluoride ions is particularly evident with respect to changes in structure and magnetic properties. The magnetic behavior was studied using field- and temperature-dependent magnetization measurements, Mößbauer spectroscopy, and neutron diffraction. Additional magnetic Bragg reflections observed in the room-temperature neutron data were successfully refined in the space group Pbca (61.1.497 in Opechowski–Guccione notation), indicating a G-type antiferromagnetic ordering with a surprisingly high Néel temperature above 300 K. This strong increase of T N by several hundred Kelvin compared to the parent oxide is particularly remarkable

Near-range receiver unit of next generation PollyXT used with Koldeway aerosol Raman lidar in Arctic

The Near-range Aerosol Raman lidar (NARLa) receiver unit, that was designed to enhance the detection range of the NeXT generation PollyXT Aerosol-Depolarization-Raman (ADR) lidar of the University of Warsaw, was employed next the Koldeway Aerosol Raman Lidar (KARL) at the AWI-IPEV German-French station in Arctic during Spring 2015. Here we introduce shortly design of both lidars, the scheme of their installation next to each other, and preliminary results of observations aiming at arctic haze investigation by the lidars and the iCAP a set of particle counter and aethalometer installed under a tethered balloon