Geochemical constraints on the origin of enigmatic cemented chalks, Norfolk, UK

Very hard cemented chalk stacks and crusts found locally in the upper part of the Cretaceous Chalk of north Norfolk, UK, are related to solution features. The solution features, mainly pipes and caves, formed after deposition of the overlying Middle Pleistocene Wroxham Crag, probably by routing of sub-glacial, or glacial, melt-waters derived from late Pleistocene glaciers. New geochemical (particularly stable isotope) data shows that cementation of the chalks, although related spatially to the solution features, was not caused by glacier-derived waters. The carbon isotope composition of the chalk cements is typically around -9.5‰, indicative of biologically active soils. Moreover, the oxygen isotope compositions of the cements, around -5‰, are incompatible with water d18O values much below -9 to -10‰ (which probably precludes isotopically negative glacier-derived water), as resulting palaeo-temperatures are below zero. Taken together, the isotope data suggest chalk cementation occurred under interglacial conditions similar to the present. Dissolved calcium carbonate for cementation came from dissolution of reworked chalk in overlying MIS 12 glacial tills

Multilayer Modelling of Lubricated Contacts: A New Approach Based on a Potential Field Description

A first integral approach, derived in an analogous fashion to Maxwell’s use of potential fields, is employed to investigate the flow characteristics, with a view to minimising friction, of shear-driven fluid motion between rigid surfaces in parallel alignment as a model for a lubricated joint, whether naturally occurring or engineered replacement. For a viscous bilayer arrangement comprised of immiscible liquids, it is shown how the flow and the shear stress along the separating interface is influenced by the mean thickness of the layers and the ratio of their respective viscosities. Considered in addition, is how the method can be extended for application to the more challenging problem of when one, or both, of the layers is a viscoelastic material

Source and purity of dengue-viral preparations impact requirement for enhancing antibody to induce elevated IL-1β secretion: A primary human monocyte model

Dengue virus is a major global health threat and can lead to life-threatening hemorrhagic complications due to immune activation and cytokine production. Cross-reactive antibodies to an earlier dengue virus infection are a recognized risk factor for severe disease. These antibodies bind heterologous dengue serotypes and enhance infection into Fc-receptorbearing cells, a process known as antibody-dependent enhancement of infection. One crucial cytokine seen elevated in severe dengue patients is IL-1β, a potent inflammatory cytokine matured by the inflammasome. We used a highly-physiologic system by studying antibody-dependent enhancement of IL-1β in primary human monocytes with anti-dengue human monoclonal antibodies isolated from patients. Antibody-enhancement increased viral replication in primary human monocytes inoculated with supernatant harvested from Vero cells infected with dengue virus serotype 2 (DENV-2) 16681. Surprisingly, IL-1β secretion induced by infectious supernatant harvested from two independent Vero cell lines was not enhanced by antibody. Secretion of multiple other inflammatory cytokines was also independent of antibody signaling. However, IL-1β secretion did require NLRP3 and caspase- 1 activity. Immunodepletion of dengue virions from the infectious supernatant confirmed that virus was not the main IL-1β-inducing agent, suggesting that a supernatant component(s) not associated with the virion induced IL-1β production. We excluded RNA, DNA, contaminating LPS, viral NS1 protein, complement, and cytokines. In contrast, purified Vero-derived DENV-2 16681 exhibited antibody-enhancement of both infection and IL-1β induction. Furthermore, C6/36 mosquito cells did not produce such an inflammatory component, as crude supernatant harvested from insect cells infected with DENV-2 16681 induced antibody-dependent IL-1β secretion. This study indicates that Vero cells infected with DENV-2 16681 may produce inflammatory components during dengue virus propagation that mask the virus-specific immune response. Thus, the choice of host cell and viral purity should be carefully considered, while insect-derived virus represents a systemthat elicits antibody- dependent cytokine responses to dengue virus with fewer confounding issues

The Effect of Epstein-Barr Virus Latent Membrane Protein 2 Expression on the Kinetics of Early B Cell Infection

Infection of human B cells with wild-type Epstein-Barr virus (EBV) in vitro leads to activation and proliferation that result in efficient production of lymphoblastoid cell lines (LCLs). Latent Membrane Protein 2 (LMP2) is expressed early after infection and previous research has suggested a possible role in this process. Therefore, we generated recombinant EBV with knockouts of either or both protein isoforms, LMP2A and LMP2B (Δ2A, Δ2B, Δ2A/Δ2B) to study the effect of LMP2 in early B cell infection. Infection of B cells with Δ2A and Δ2A/Δ2B viruses led to a marked decrease in activation and proliferation relative to wild-type (wt) viruses, and resulted in higher percentages of apoptotic B cells. Δ2B virus infection showed activation levels comparable to wt, but fewer numbers of proliferating B cells. Early B cell infection with wt, Δ2A and Δ2B viruses did not result in changes in latent gene expression, with the exception of elevated LMP2B transcript in Δ2A virus infection. Infection with Δ2A and Δ2B viruses did not affect viral latency, determined by changes in LMP1/Zebra expression following BCR stimulation. However, BCR stimulation of Δ2A/Δ2B cells resulted in decreased LMP1 expression, which suggests loss of stability in viral latency. Long-term outgrowth assays revealed that LMP2A, but not LMP2B, is critical for efficient long-term growth of B cells in vitro. The lowest levels of activation, proliferation, and LCL formation were observed when both isoforms were deleted. These results suggest that LMP2A appears to be critical for efficient activation, proliferation and survival of EBV-infected B cells at early times after infection, which impacts the efficient long-term growth of B cells in culture. In contrast, LMP2B did not appear to play a significant role in these processes, and long-term growth of infected B cells was not affected by the absence of this protein. © 2013 Wasil et al

Conclusions from the Engineering Subgroup of the SSC Liquid Argon Calorimeter Working Group

The SSC Calorimeter workshop was organized to explore the feasibility of each calorimeter technology for use in a 4..pi.. detector at the SSC. The Liquid Argon Calorimeter group further subdivided into four subgroups; Hermeticity, Engineering, Module Details, and Electronics. This is the report of the Engineering Subgroup whose charge was to evaluate the cost, schedule, manpower, safety, and facilities requirements for the construction of a large liquid argon calorimeter for the SSC. 4 figs., 4 tabs

4th Biennial Employment Law Institute

Materials from the 4th Biennial Employment Law Institute held by UK/CLE in June 1994

West Nile Virus Genetic Diversity is Maintained during Transmission by Culex pipiens quinquefasciatus Mosquitoes

Due to error-prone replication, RNA viruses exist within hosts as a heterogeneous population of non-identical, but related viral variants. These populations may undergo bottlenecks during transmission that stochastically reduce variability leading to fitness declines. Such bottlenecks have been documented for several single-host RNA viruses, but their role in the population biology of obligate two-host viruses such as arthropod-borne viruses (arboviruses) in vivo is unclear, but of central importance in understanding arbovirus persistence and emergence. Therefore, we tracked the composition of West Nile virus (WNV; Flaviviridae, Flavivirus) populations during infection of the vector mosquito, Culex pipiens quinquefasciatus to determine whether WNV populations undergo bottlenecks during transmission by this host. Quantitative, qualitative and phylogenetic analyses of WNV sequences in mosquito midguts, hemolymph and saliva failed to document reductions in genetic diversity during mosquito infection. Further, migration analysis of individual viral variants revealed that while there was some evidence of compartmentalization, anatomical barriers do not impose genetic bottlenecks on WNV populations. Together, these data suggest that the complexity of WNV populations are not significantly diminished during the extrinsic incubation period of mosquitoes

Occurrence of Corynebacterium striatum as an emerging antibiotic-resistant nosocomial pathogen in a Tunisian hospital

Corynebacterium striatum is a nosocomial opportunistic pathogen increasingly associated with a wide range of human infections and is often resistant to several antibiotics. We investigated the susceptibility of 63 C. striatum isolated at the Farhat-Hached hospital, Sousse (Tunisia), during the period 2011?2014, to a panel of 16 compounds belonging to the main clinically relevant classes of antimicrobial agents. All strains were susceptible to vancomycin, linezolid, and daptomycin. Amikacin and gentamicin also showed good activity (MICs90 = 1 and 2 mg/L, respectively). High rates of resistance to penicillin (82.5%), clindamycin (79.4%), cefotaxime (60.3%), erythromycin (47.6%), ciprofloxacin (36.5%), moxifloxacin (34.9%), and rifampicin (25.4%) were observed. Fifty-nine (93.7%) out of the 63 isolates showed resistance to at least one compound and 31 (49.2%) were multidrug-resistant. Twenty-nine resistance profiles were distinguished among the 59 resistant C. striatum. Most of the strains resistant to fluoroquinolones showed a double mutation leading to an amino acid change in positions 87 and 91 in the quinolone resistance-determining region of the gyrA gene. The 52 strains resistant to penicillin were positive for the gene bla, encoding a class A ?-lactamase. Twenty-two PFGE patterns were identified among the 63 C. striatum, indicating that some clones have spread within the hospital