Integrated Calendar

"The asymptotic structure of three-dimensional gravity with a negative cosmological constant is reviewed with a special emphasis on the central charge that appears in the asymptotic conformal symmetry algebra. Higher spin extensions, which were recently investigated, are discussed"

Biological systems display complex networks of interactions, both at the level of molecules inside the cell and at the level of interactions between cells. Networks of interacting molecules, such as transcription networks, have been shown to be composed of recurring circuit designs, each with specific dynamical functions. Much less is known about the possibility of such circuit analysis in networks made of communicating cells. Here we study models of circuits in which a few cell types interact by means of signaling molecules. We consider circuits of cells with architectures that seem to recur in immunology. We find that signaling molecules with a pleiotropic or paradoxical role, such as cytokines that have multiple functions and even antagonistic functions, can provide cell circuits with systems-level functions. These functions include, for different circuits, homeostatic concentration of differentiated cells, fold-detection of input signals with exact adaptation, and a robust stereotyped pulse of cytokine production.

Abstract: Understanding the impacts of climate change is one of the great challenges we are facing today. A warmer climate will impact both terrestrial and ocean ecosystems in ways we do not fully understand. We need to understand the tightly coupled biogeochemical cycles (carbon, nitrogen, water, etc.) and the important drivers of those cycles that occur at all scales of biogeochemical organization. Terrestrial ecosystems that have been identified to be particularly important include tropical forests, boreal forests, peatlands, and arctic permafrost. These ecosystems contain large quantities of carbon that if released to the atmosphere as CO2 or CH4 could provide significant positive feedback to the climate system and exacerbate global warming. Current climate models predict a significant increase in thawing depths and durations of thawing, turning permafrost land into wetlands or thermokarsts where microorganisms can mineralize complex organic matter and release CO2 and CH4 as well as N2O and other GHG. Two next-generation ecosystem experiments are being planned for deployment that will shed light on these important processes. An experiment to expose a boreal forest – peat bog ecosystem in Grand Rapids, MN, USA to both warmer temperatures and elevated CO2 concentrations is under development using an innovative combination of belowground and aboveground warming technology while also enriching the CO2 concentration in the atmosphere around the forest. A second experiment is being considered for implementation in the permafrost in Alaska, USA. These experiments offer unique opportunities for microbiologists to collaborate with plant biologists, ecologists, and geologists. The scientific opportunities to explore biogeochemical cycles at multiple scales with modern biological, chemical, and physical methods is unprecedented and will challenge us to develop new informatics tools to integrate these new data that span disciplines and scales. With these integrative studies we may begin to open up the proverbial black box and quantify important interfacial and molecular biogeochemical processes.

The Large Hadron Collider (LHC) at CERN is opening up the TeV energy scale for exploration. We fully expect we will soon begin a new era in particle physics that will provide strong motivation to build a companion accelerator, a lepton collider. In anticipation, the International Linear Collider (ILC) is being conceived and designed by a unique global process involving coordinated R&D and design work by leading accelerator physicists worldwide. A TeV scale linear collider could enable us to zoom in on the new landscape found at the LHC with great precision, revealing its richness and new layers of detail.

The ILC is technically a very challenging enterprise, involving development of high gradient superconducting radio-frequency (SCRF) accelerating cavities. To achieve the required event rate will require both high power and very small emittance beams. A reference design for the ILC has been developed and we hope to build such a machine on a timescale of the early 2020s.