An antagonist peptide mediates positive selection and CD4 lineage commitment of MHC class II–restricted T cells in the absence of CD4

The CD4 coreceptor works together with the T cell receptor (TCR) to deliver signals to the developing thymocyte, yet its specific contribution to positive selection and CD4 lineage commitment remains unclear. To resolve this, we used N3.L2 TCR transgenic, RAG-, and CD4-deficient mice, which are severely impaired in positive selection, and asked whether altered peptide ligands can replace CD4 function in vivo. Remarkably, in the presence of antagonist ligands that normally deleted CD4+ T cells in wild-type mice, we induced positive selection of functional CD4 lineage T cells in mice deficient in CD4. We show that the kinetic threshold for positive and negative selection was lowered in the absence of CD4, with no evident skewing toward the CD8 lineage with weaker ligands. These results suggest that CD4 is dispensable as long as the affinity threshold for positive selection is sustained, and strongly argue that CD4 does not deliver a unique instructional signal for lineage commitment

Immunomodulatory roles of polysaccharide capsules in the intestine

The interplay between the immune system and the microbiota in the human intestine dictates states of health vs. disease. Polysaccharide capsules are critical elements of bacteria that protect bacteria against environmental and host factors, including the host immune system. This review summarizes the mechanisms by which polysaccharide capsules from commensal and pathogenic bacteria in the gut microbiota modulate the innate and adaptive immune systems in the intestine. A deeper understanding of the roles of polysaccharide capsules in microbiota-immune interactions will provide a basis to harness their therapeutic potential to advance human health

Crossing Chronotopes in the Polyphonic Organisation: A dialogical analysis of the comedy industry

YesThe ‘Polyphonic Organisation’ is an emerging root-metaphor for the multiple voices that constitute an organisation. In this article, we explore the narrative concept of the ‘chronotope’ as a feature of the ‘polyphonic organisation’. The ‘chronotope’, in a general sense, refers to the matrix of time-space-value in organisations. We argue that the chronotope is important because it introduces boundaries between voices within organisations and helps to explain the difficulties in getting to dialogue with voices in different spaces in the ‘Polyphonic Organisation’. More particularly, there are multiple kinds of chronotopes which lead to different kinds of time-spaces matrices within the polyphonic organisation. Our aim is to examine chronotope crossings within polyphonic organisations as part of the work of being heard. This is a theoretical argument drawing significantly from Bakhtin’s work on chronotope. To examine the argument in practice we draw on original fieldwork within the comedy industry. Here we found three kinds of chronotopes: 1) The comedy-offense boundary; 2) The commissioning landscape 3) Platform spaces. We also found that moving within and between these involved a variety of adventures in experience (such as hope and disappointment), which also have their own specific chronotopes. Overall, we argue that the polyphonic organisation is significantly enhanced as an organisational concept through a turn to the role of chronotope. This is because chronotope helpfully describes the barriers and porous boundaries between voice

Anomalous Seismic Amplitudes Measured in the Los Angeles Basin Interpreted as a Basin-Edge Diffraction Catastrophe

The Los Angeles Basin Passive Seismic Experiment (labpse) involved the installation of an array of 18 seismic stations along a line crossing the Los Angeles basin from the foothills of the San Gabriel Mountains through the Puente Hills to the coast. At 3–5 km spacing between stations the array has much higher resolution than the permanent network of stations in southern California. This resolution was found to be important for analyzing the factors that govern the amplitude variation across the basin. We inverted spectra of P- and S-body-wave seismograms from local earthquakes (M_L 2.1–4.8) for site effects, attenuation, and corner frequency factor using a standard model that assumes geometric spreading varying as inverse distance, exponential attenuation, and an ω^2 source model. The S-wave attenuation was separable into basin and bedrock contributions. In addition to the body-wave analysis, S-wave coda were analyzed for coda Q and coda-determined site effects. We find S- wave Q (Q_S) in bedrock is higher than in the basin. High-frequency Q_S is higher than low-frequency Q_S. Coda Q (Q_c) is higher than Q_S. P-wave Q (Q_P) was not separable into basement and bedrock values, so we determined an average value only. The corner frequencies for P and S waves were found to be nearly the same. The standard model fit over 97% of the S-wave data, but data from six clustered events incident along the basin edge within a restricted range of incidence and azimuth angles generated anomalous amplitudes of up to a factor of 5 higher than predicted. We test whether such basin-edge focusing might be modeled by catastrophe theory. After ruling out site, attenuation, and radiation effects, we conclude a caustic modeled as a diffraction catastrophe could explain both the frequency and spatial dependence of the anomalous variation

Ariel - Volume 2 Number 2

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