Testing Observational Techniques with 3D MHD Jets in Clusters

Observations of X-ray cavities formed by powerful jets from AGN in galaxy cluster cores are commonly used to estimate the mechanical luminosity of these sources. We test the reliability of observationally measuring this power with synthetic X-ray observations of 3-D MHD simulations of jets in a galaxy cluster environment. We address the role that factors such as jet intermittency and orientation of the jets on the sky have on the reliability of observational measurements of cavity enthalpy and age. An estimate of the errors in these quantities can be made by directly comparing ``observationally'' derived values with values from the simulations. In our tests, cavity enthalpy, age and mechanical luminosity derived from observations are within a factor of two of the simulation values.Comment: 4 pages, 3 figures; to appear in proceedings of The Monster's Fiery Breath: Feedback in Galaxies, Groups, and Clusters (AIP conference series

A generating function approach to the automated evaluation of sums of exponentiated multiples of generalized Catalan number linear combinations.

Based on a previous technique deployed in some specific low order cases, we develop an automated computational procedure to evaluate instances within a class of infinite series comprising exponentiated multiples of generalized linear combinations of Catalan numbers. The methodology is explained, and new results given.N/

The B subunit of Escherichia coli heat-labile toxin alters the development and antigen-presenting capacity of dendritic cells

Escherichia coli’s heat-labile enterotoxin (Etx) and its non-toxic B subunit (EtxB) have been characterized as adjuvants capable of enhancing T cell responses to co-administered antigen. Here, we investigate the direct effect of intravenously administered EtxB on the size of the dendritic and mye-loid cell populations in spleen. EtxB treatment appears to enhance the development and turnover of dendritic and myeloid cells from precursors within the spleen. EtxB treatment also gives a dendritic cell (DC) population with higher viability and lower activation status based on the reduced expression of MHC-II, CD80 and CD86. In this respect, the in vivo effect of EtxB differs from that of the highly inflammatory mediator lipopolysaccharide. In in vi-tro bone marrow cultures, EtxB treatment was also found to enhance the development of DC from precursors dependent on Flt3L. In terms of the in vivo effect of EtxB on CD4 and CD8 T cell responses in mice, the interaction of EtxB directly with DC was demonstrated following conditional deple-tion of CD11c+ DC. In summary, all results are consistent with EtxB displaying adjuvant ability by enhancing the turnover of DC in spleen, leading to newly mature myeloid and DC in spleen, thereby increasing DC capacity to perform as antigen-presenting cells on encounter with T cells

Tectonostratigraphic controls on pore fluid pressure distribution across the Taranaki Basin, New Zealand

Significant variations in pore pressure across the Taranaki Basin, New Zealand, are attributed to changes in lithofacies and structure, usefully illustrated in terms of ten areas that we term geopressure provinces, each displaying individual pore pressure trends. Cretaceous to Early Miocene formations in different parts of the basin can be either normally pressured (near or at hydrostatic) or significantly overpressured (up to 28 MPa) at the same depth. Variations in Eocene–Oligocene facies types and thicknesses both within and between geopressure provinces provide first-order control on the magnitude, distribution and maintenance of overpressure across the basin. Examples of hydraulic compartmentalisation due to sealing faults and stratigraphic architecture are identified within the basin. Deep pore pressure transitions are sealed by diagenetic, structural or stratigraphic mechanisms in different places and are associated with an increase in mudrock volume (reduced permeability) or gas generation. Thus, pore pressure distribution in the Taranaki Basin is controlled by a combination of sediment loading, lithofacies variations, fault zone permeability and structural architecture. This work represents an appraisal of the pore pressure distribution across the whole of a multiphase structurally complex basin, and the approach taken provides a framework for better understanding the distribution of pore fluid pressures and pore fluid migration in other sedimentary basins

A comparison of transhepatic versus transperitoneal cholecystostomy for acute calculous cholecystitis: a 5-year experience.

Percutaneous cholecystostomy is a treatment for acute calculous cholecystitis used in patients where surgery is high risk or challenging either to allow for surgical optimisation or as definitive treatment. In this case series we compare the outcomes of a transhepatic versus transperitoneal approach in patients undergoing percutaneous cholecystostomy for acute calculous cholecystitis. A retrospective review of patients from 2014 to 2019 was conducted and included demographics, percutaneous cholecystostomy route, complications and outcome. Fifty-one patients were included. Percutaneous cholecystostomy was placed transhepatically in 15 cases; transperitoneal in 30 cases; 6 cases had undetermined route. The transhepatic cohort had 43.5% fewer readmissions due to biliary sepsis, 32.5% fewer drain-related complications, and were less likely to require further treatment (32.5% reduction) compared to the transperitoneal cohort. In our experience, the transhepatic route is preferred due to fewer complications, fewer readmissions and a reduction in the need for further treatment

Voltage Controlled Hot Carrier Injection Enables Ohmic Contacts Using Au Island Metal Films on Ge

We introduce a new approach to creating low-resistance metalsemiconductor ohmic contacts, illustrated using high conductivity Au island metal films (IMFs) on Ge, with hot carrier injection initiated at low applied voltage. The same metallization process simultaneously allows ohmic contact to n-Ge and p-Ge, because hot carriers circumvent the Schottky barrier formed at metal/n-Ge interfaces. A 2.5x improvement in contact resistivity is reported over previous techniques to achieve ohmic contact to both n- and p- semiconductor. Ohmic contacts at 4.2 K confirm nonequilibrium current transport. Self-assembled Au IMFs are strongly orientated to Ge by annealing near the Au/Ge eutectic temperature. Au IMF nanostructures form, provided the Au layer is below a critical thickness. We anticipate that optimized IMF contacts may have applicability to many material systems. Optimizing this new paradigm for metalsemiconductor contacts offers the prospect of improved nanoelectronic systems and the study of voltage controlled hot holes and electrons.Peer reviewe

The effects of sulphur poisoning on the microstructure, composition and oxygen transport properties of perovskite membranes coated with nanoscale alumina layers

Perovskite oxides displaying mixed ionic and electronic conductivity have attracted a lot of interest for application in oxygen separation membranes. Such membranes could be used for a range of processes, including the conversion of natural gas to hydrogen or syngas. A major limitation of these materials is their tendency to segregate into simpler oxides under operating conditions, reacting with sulphur-based species often found in natural gas and leading to irreversible membrane degradation over time. Here we aim to delay or prevent this process by coating La0.6Sr0.4Co0.2Fe0.8O3-δ membranes with Alumina (Al2O3) layers of 1–100 nm thickness by using atomic layer deposition. We show that coatings of about 30 nm have negligible negative effect on O2 transport flux across the membrane and display good flux recovery when H2S is removed from the stream. Coatings thinner than this critical value provide little protection against irreversible poisoning while thicker coatings dramatically decrease overall O2 permeation fluxes. We also show that the irreversible sulphur poisoning under O2 permeation conditions is linked to microstructural and composition changes at the membrane surface caused predominantly by the formation of SrSO4 particles at the perovskite grain boundaries