Employing pre-stress to generate finite cloaks for antiplane elastic waves

It is shown that nonlinear elastic pre-stress of neo-Hookean hyperelastic materials can be used as a mechanism to generate finite cloaks and thus render objects near-invisible to incoming antiplane elastic waves. This approach appears to negate the requirement for special cloaking metamaterials with inhomogeneous and anisotropic material properties in this case. These properties are induced naturally by virtue of the pre-stress. This appears to provide a mechanism for broadband cloaking since dispersive effects due to metamaterial microstructure will not arise.Comment: 4 pages, 2 figure

Neutral hydrogen gas, past and future star-formation in galaxies in and around the 'Sausage' merging galaxy cluster

CIZA J2242.8+5301 ($z = 0.188$, nicknamed 'Sausage') is an extremely massive ($M_{200}\sim 2.0 \times 10^{15}M_\odot$ ), merging cluster with shock waves towards its outskirts, which was found to host numerous emission-line galaxies. We performed extremely deep Westerbork Synthesis Radio Telescope HI observations of the 'Sausage' cluster to investigate the effect of the merger and the shocks on the gas reservoirs fuelling present and future star formation (SF) in cluster members. By using spectral stacking, we find that the emission-line galaxies in the 'Sausage' cluster have, on average, as much HI gas as field galaxies (when accounting for the fact cluster galaxies are more massive than the field galaxies), contrary to previous studies. Since the cluster galaxies are more massive than the field spirals, they may have been able to retain their gas during the cluster merger. The large HI reservoirs are expected to be consumed within $\sim0.75-1.0$ Gyr by the vigorous SF and AGN activity and/or driven out by the out-flows we observe. We find that the star-formation rate in a large fraction of H$\alpha$ emission-line cluster galaxies correlates well with the radio broad band emission, tracing supernova remnant emission. This suggests that the cluster galaxies, all located in post-shock regions, may have been undergoing sustained SFR for at least 100 Myr. This fully supports the interpretation proposed by Stroe et al. (2015) and Sobral et al. (2015) that gas-rich cluster galaxies have been triggered to form stars by the passage of the shock.Comment: Accepted to MNRAS, 14 pages, 9 figures, 7 table

Molecular crosstalk between apoptosis, necroptosis, and survival signaling

Our current knowledge of the molecular mechanisms regulating the signaling pathways leading to cell survival, cell death, and inflammation has shed light on the tight mutual interplays between these processes. Moreover, the fact that both apoptosis and necrosis can be molecularly controlled has greatly increased our interest in the roles that these types of cell death play in the control of general processes such as development, homeostasis, and inflammation. In this review, we provide a brief update on the different cell death modalities and describe in more detail the intracellular crosstalk between survival, apoptotic, necroptotic, and inflammatory pathways that are activated downstream of death receptors. An important concept is that the different cell death processes modulate each other by mutual inhibitory mechanisms, serve as alternative back-up death routes in the case of a defect in the first-line cell death response, and are controlled by multiple feedback loops. We conclude by discussing future perspectives and challenges in the field of cell death and inflammation research

The Brightening of Re50N: Accretion Event or Dust Clearing?

The luminous Class I protostar HBC 494, embedded in the Orion A cloud, is associated with a pair of reflection nebulae, Re50 and Re50N, which appeared sometime between 1955 and 1979. We have found that a dramatic brightening of Re50N has taken place sometime between 2006 and 2014. This could result if the embedded source is undergoing a FUor eruption. However, the near-infrared spectrum shows a featureless very red continuum, in contrast to the strong CO bandhead absorption displayed by FUors. Such heavy veiling, and the high luminosity of the protostar, is indicative of strong accretion but seemingly not in the manner of typical FUors. We favor the alternative explanation that the major brightening of Re50N and the simultaneous fading of Re50 is caused by curtains of obscuring material that cast patterns of illumination and shadows across the surface of the molecular cloud. This is likely occurring as an outflow cavity surrounding the embedded protostar breaks through to the surface of the molecular cloud. Several Herbig-Haro objects are found in the region.Comment: 8 pages, accepted by Ap

Ariel - Volume 2 Number 3

Editors Delvyn C. Case, Jr. Paul M. Fernhoff News Editors Richard Bonanno Daniel B. Gould Robin A. Edwards Lay-Out Editor Carol Dolinskas Sports Editor James J. Nocon Contributing Editors Michael J. Blecker Lin Sey Edwards Jack Guralnik W. Cherry Light Features Editor Steven A. Ager Donald A. Bergman Stephen P. Flynn Business Manager Nick Greg

Restriction Spectrum Imaging Differentiates True Tumor Progression From Immune-Mediated Pseudoprogression: Case Report of a Patient With Glioblastoma.

Immunotherapy is increasingly used in the treatment of glioblastoma (GBM), with immune checkpoint therapy gaining in popularity given favorable outcomes achieved for other tumors. However, immune-mediated (IM)-pseudoprogression is common, remains poorly characterized, and renders conventional imaging of little utility when evaluating for treatment response. We present the case of a 64-year-old man with GBM who developed pathologically proven IM-pseudoprogression after initiation of a checkpoint inhibitor, and who subsequently developed true tumor progression at a distant location. Based on both qualitative and quantitative analysis, we demonstrate that an advanced diffusion-weighted imaging (DWI) technique called restriction spectrum imaging (RSI) can differentiate IM-pseudoprogression from true progression even when conventional imaging, including standard DWI/apparent diffusion coefficient (ADC), is not informative. These data complement existing literature supporting the ability of RSI to estimate tumor cellularity, which may help to resolve complex diagnostic challenges such as the identification of IM-pseudoprogression

Boiling-induced formation of colloidal gold in black smoker hydrothermal fluids

Gold colloids occur in black smoker fluids from the Niua South hydrothermal vent field, Lau Basin (South Pacific Ocean), confirming the long-standing hypothesis that gold may undergo colloidal transport in hydrothermal fluids. Six black smoker vents, varying in temperature from 250 °C to 325 °C, were sampled; the 325 °C vent was boiling at the time of sampling and the 250 °C fluids were diffusely venting. Native gold particles ranging from <50 nm to 2 μm were identified in 4 of the fluid samples and were also observed to precipitate on the sampler during collection from the boiling vent. Total gold concentrations (dissolved and particulate) in the fluid samples range from 1.6 to 5.4 nM in the high-temperature, focused flow vents. Although the gold concentrations in the focused flow fluids are relatively high, they are lower than potential solubilities prior to boiling and indicate that precipitation was boiling induced, with sulfide lost upon boiling to exsolution and metal sulfide formation. Gold concentrations reach 26.7 nM in the 250 °C diffuse flow sample, and abundant native gold particles were also found in the fluids and associated sulfide chimney and are interpreted to be a product of colloid accumulation and growth following initial precipitation upon boiling. These results indicate that colloid-driven precipitation as a result of boiling, the persistence of colloids after boiling, and the accumulation of colloids in diffuse flow fluids are important mechanisms for the enrichment of gold in seafloor hydrothermal systems

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