Global Solutions for the Gravity Water Waves Equation in Dimension 3

We show existence of global solutions for the gravity water waves equation in dimension 3, in the case of small data. The proof combines energy estimates, which yield control of L^2 related norms, with dispersive estimates, which give decay in L^\infty. To obtain these dispersive estimates, we use an analysis in Fourier space; the study of space and time resonances is then the crucial point

Two hats too many

AbstractMy Word: Ronald N. Germain believes it's time scientists eliminated splits in their personality between researching and reviewing

A spatially-organized multicellular innate immune response in lymph nodes limits systemic pathogen spread

The lymphatic network that transports interstitial fluid and antigens to lymph nodes constitutes a conduit system that can be hijacked by invading pathogens to achieve systemic spread unless dissemination is blocked in the lymph node itself. Here, we show that a network of diverse lymphoid cells (natural killer cells, γδ T cells, natural killer T cells, and innate-like CD8+ T cells) are spatially prepositioned close to lymphatic sinus-lining sentinel macrophages where they can rapidly and efficiently receive inflammasome-generated IL-18 and additional cytokine signals from the pathogen-sensing phagocytes. This leads to rapid IFNγ secretion by the strategically positioned innate lymphocytes, fostering antimicrobial resistance in the macrophage population. Interference with this innate immune response loop allows systemic spread of lymph-borne bacteria. These findings extend our understanding of the functional significance of cellular positioning and local intercellular communication within lymph nodes while emphasizing the role of these organs as highly active locations of innate host defense

Cross-Antagonism of a T Cell Clone Expressing Two Distinct T Cell Receptors

AbstractInhibition of T cell activation can be mediated by analogs of the original antigenic peptide (TCR antagonists). Here, a T cell clone expressing two distinct TCR was used to investigate whether such inhibition involves an active mechanism by examining whether an antagonist for one TCR could influence responses stimulated by the other TCR engaging its agonist. Our results demonstrate functional cross-inhibition under these conditions involving the ability of antagonist:TCR interactions to diminish Lck enzymatic activity associated with the agonist-recognizing second TCR, apparently through enhancement of SHP-1 association with these receptors. Our findings reveal that inhibition of cellular responses by antagonists arises at least in part from active negative regulation of proximal TCR signaling and identify elements of the biochemical process

Revisiting Thymic Positive Selection and the Mature T Cell Repertoire for Antigen

To support effective host defense, the T cell repertoire must balance breadth of recognition with sensitivity for antigen. The concept that T lymphocytes are positively selected in the thymus is well established, but how this selection achieves such a repertoire has not been resolved. Here we suggest that it is direct linkage between self and foreign antigen recognition that produces the necessary blend of TCR diversity and specificity in the mature peripheral repertoire, enabling responses to a broad universe of unpredictable antigens while maintaining an adequate number of highly sensitive T cells in a population of limited size. Our analysis also helps to explain how diversity and frequency of antigen-reactive cells in a T cell repertoire are adjusted in animals of vastly different size scale to enable effective antipathogen responses and suggests a possible binary architecture in the TCR repertoire that is divided between germline-related optimal binding and diverse recognition

Illuminating the Landscape of In Vivo Immunity Insights from Dynamic In Situ Imaging of Secondary Lymphoid Tissues

AbstractA central feature of the immune system is the migratory behavior of its cellular components. Thus, fully understanding the generation and maintenance of immune responses must include consideration of how hematopoietic cells home to, interact within, and exit from secondary lymphoid organs as well as peripheral tissues. Recent advances in in situ imaging techniques now permit direct observation of these events in their physiologic settings with high spatiotemporal resolution. This review summarizes progress in this area of investigation from a lymphocentric perspective. We highlight controversies, point out key unanswered questions, and briefly outline what we believe are some of the near-term directions that in situ microscopic analysis of the immune system will take

Tapping wave energy through Longuet-Higgins microseism effect

International audienceIt is well-known, since the works of Miche (1944) and Longuet-Higgins (1950), that, under a standing wave system, second-order pressures at twice the wave frequency penetrate the water column down to the sea-°oor, whatever the waterdepth. Recently Gu¶evel proposed that energy could be extracted from the waves with a heaving horizontal plate at the sea bottom, located next to a re°ective cli® or sea-wall, and tuned to oscillate at twice the wave frequency. Encouraging preliminary experiments were conducted in ACRI's wavetank (Lajoie et al. 2007). In this paper we address the theoretical modeling of wave energy extraction with such a device, in the asymptotic case when the waterdepth is very large compared to the wavelength. In section I we assume that the ¯rst-order wave system is little modi¯ed, i.e. the power taken from the waves is a small portion of the power carried by the incoming wave. In section II we relieve this assumption and we show that one hundred percent of the wave power can be extracted, notwithstanding how large the waterdepth