Kosmisk frygt: eller den dag Brad Pitt fik paranoia

A new play by Danish playwright Christian Lollike dealing with global warming

Blockchain – The Gateway to Trust-Free Cryptographic Transactions

Recently, the Bitcoin-underlying blockchain technology gained prominence as a solution that offers the realization of distributed trust-free systems, where economic transactions are guaranteed by the underlying blockchain. We are still at an early stage and thus require a deeper understanding of how the blockchain potentials can be realized, and what are the opportunities and challenges in so doing. Following a design science approach, we developed a proof of concept prototype that has the poten-tial to replace a trust-based coffee shop payment solution that is based on an analogue, pre-paid punch card solution. The demonstrator provides a starting point to evaluate the strengths and weak-nesses of the blockchain technology when replacing a trust-based by a trust-free transaction system. We conclude that the secure and trust-free blockchain-based transaction has the potential to change many existing trust-based transaction systems, but that scalability issues, costs, and volatility in the transaction currency are hindrances

Multivesicular exocytosis in rat pancreatic beta cells

AIMS/HYPOTHESIS: To establish the occurrence, modulation and functional significance of compound exocytosis in insulin-secreting beta cells. METHODS: Exocytosis was monitored in rat beta cells by electrophysiological, biochemical and optical methods. The functional assays were complemented by three-dimensional reconstruction of confocal imaging, transmission and block face scanning electron microscopy to obtain ultrastructural evidence of compound exocytosis. RESULTS: Compound exocytosis contributed marginally (<5% of events) to exocytosis elicited by glucose/membrane depolarisation alone. However, in beta cells stimulated by a combination of glucose and the muscarinic agonist carbachol, 15-20% of the release events were due to multivesicular exocytosis, but the frequency of exocytosis was not affected. The optical measurements suggest that carbachol should stimulate insulin secretion by ∼40%, similar to the observed enhancement of glucose-induced insulin secretion. The effects of carbachol were mimicked by elevating [Ca(2+)](i) from 0.2 to 2 μmol/l Ca(2+). Two-photon sulforhodamine imaging revealed exocytotic events about fivefold larger than single vesicles and that these structures, once formed, could persist for tens of seconds. Cells exposed to carbachol for 30 s contained long (1-2 μm) serpentine-like membrane structures adjacent to the plasma membrane. Three-dimensional electron microscopy confirmed the existence of fused multigranular aggregates within the beta cell, the frequency of which increased about fourfold in response to stimulation with carbachol. CONCLUSIONS/INTERPRETATION: Although contributing marginally to glucose-induced insulin secretion, compound exocytosis becomes quantitatively significant under conditions associated with global elevation of cytoplasmic calcium. These findings suggest that compound exocytosis is a major contributor to the augmentation of glucose-induced insulin secretion by muscarinic receptor activation

Membrane capacitance techniques to monitor granule exocytosis in neutrophils.

Cell membranes behave like electrical capacitors and changes in cell capacitance therefore reflect changes in the cell area. Monitoring capacitance can thus be used to study dynamic cellular phenomenon involving rapid changes in cell surface, such as exo- and/or endocytosis. In this review focus is on the use of capacitance techniques to study exocytosis in human neutrophils. We compare the whole-cell and the cell-attached capacitance techniques, and we review the complete literature dealing with capacitance measurements in human neutrophils