Sliding of temperate basal ice on a rough, hard bed: creep mechanisms, pressure melting, and implications for ice streaming

Basal ice motion is crucial to ice dynamics of ice sheets. The classic Weertman model for basal sliding over bedrock obstacles proposes that sliding velocity is controlled by pressure melting and/or ductile flow, whichever is the fastest; it further assumes that pressure melting is limited by heat flow through the obstacle and ductile flow is controlled by standard power-law creep. These last two assumptions, however, are not applicable if a substantial basal layer of temperate (T � Tmelt/ ice is present. In that case, frictional melting can produce excess basal meltwater and efficient water flow, leading to near-thermal equilibrium. High-temperature ice creep experiments have shown a sharp weakening of a factor 5–10 close to Tmelt, suggesting standard power-law creep does not operate due to a switch to melt-assisted creep with a possible component of grain boundary melting. Pressure melting is controlled by meltwater production, heat advection by flowing meltwater to the next obstacle and heat conduction through ice/rock over half the obstacle height. No heat flow through the obstacle is required. Ice streaming over a rough, hard bed, as possibly in the Northeast Greenland Ice Stream, may be explained by enhanced basal motion in a thick temperate ice layer

The role of small conductance calcium-activated potassium channels in mitochondrial dysfunction:Targeting metabolic reprogramming and calcium homeostasis

Neurodegenerative diseases are characterized by progressive cell death, often attributed to mitochondrial dysfunction, inflammation and oxidative stress. The main aim of this thesis was to investigate the role of SK channels on calcium homeostasis, reactive oxygen species (ROS) and mitochondrial metabolism, in neurodegenerative conditions, inflammation and brain cancer. We showed that pharmacologically modulating mitochondrial KCa channels mediates cellular protection against oxidative stress through mitochondrial preconditioning in neurodegenerative conditions. Investigating the role of mitochondrial calcium in oxidative stress, we demonstrated that an enhanced endoplasmic reticulum – mitochondrial interface induced mitochondrial calcium overload in conditions of oxidative stress, and impaired mitochondrial bioenergetics, events that were prevented by SK channel activator CyPPA. Further, we showed that attenuation of mitochondrial calcium uptake using mitoxantrone and ruthenium red preserved cell viability in ferroptosis. Thus, attenuation of mitochondrial calcium, in particular via activation of SK channels, plays a crucial role in cellular protection against oxidative stress. Neuroprotective effects of SK channel activation against ferroptosis also involve adaptations in cellular metabolism. CyPPA induced an initial metabolic shift towards glycolysis, followed by a small reduction in mitochondrial complex activity and a mild induction of mitochondrial ROS. In vivo, CyPPA increased lactate production, median lifespan and mitochondrial stress resistance. Besides, CyPPA attenuated LPS-induced macrophage activation, even in conditions potentiated by succinate, possibly via reducing reverse electron transfer. Finally, we reported that SK channel activation can promote anti-tumour capacities of the classical anti-cancer agent auranofin in brain cancer cells, due to enhancing ROS levels and mitochondrial dysfunction

Michael Patrick Cullinane and Clare Frances Elliott, eds. Perspectives on Presidential Leadership. An International View of the White House

This valuable collection of essays serves two purposes. It contributes to a systematic evaluation of the quality of presidential leadership from a perspective outside America. And it shows a variety of approaches to presidential leadership. Thirteen “Commonwealth” authors created this outsider perspective by examining the quality and legacy of thirteen presidents. This volume grew out of a 2011 British survey where participants ranked American presidents. The editors and creators of the surve..

Human innate lymphoid cells:From helper to killer

Innate Lymphoid Cells (ILCs) control tissue and metabolic homeostasis, but also provide protection from infectious diseases. Strategically located in barrier tissues, ILCs produce effector cytokines in an antigen-independent manner, thereby mounting an appropriate immune response to pathogens at mucosal sites. ILCs are classified into three subsets of helper ILCs, each producing their signature cytokines, and cytotoxic Natural Killer (NK) cells. Their plastic nature allows helper ILC subsets to promptly respond to the changing environment by adapting its function and phenotype. However, when not properly regulated, ILCs can contribute to chronic inflammation, autoimmune disease and cancer. Therefore, it is of importance to identify the essential factors involved in the development and functions of ILCs. In this thesis we describe the methods to isolate ILCs from human mucosal tissues. We identified an essential transcription factor for the development of ILCs by studying the immune cell composition of GATA2-deficient patients. Furthermore, we investigated the full spectrum and the plasticity of human ILCs and NK cells in the tonsil and intestine. Thereby we identified cytotoxic ILCs which are distinct from NK cells and unraveled their developmental requirements. Furthermore, we investigated the ILC composition in the inflamed intestinal tissue of Crohn’s disease patients compared to non-inflamed controls, and observed that particular ILC subsets that express high levels of cytotoxic molecules and type 1 cytokines expanded in inflamed tissues. Our findings contribute to a better understanding of the functions of ILCs and their possible roles in inflammatory diseases of the intestine

Frank Mehring, The Democratic Gap: Transcultural Confrontations of German Immigrants and the Promise of American Democracy

Frank Mehring, The Democratic Gap: Transcultural Confrontations of German Immigrants and the Promise of American Democracy. Heidelberg: Winter Verlag, 2014. 419pp.  ISBN: 978-3-8253-6170-9. Hans Krabbendam Roosevelt Study Center, Middelburg This award-winning book by Frank Mehring, professor at Radboud University Nijmegen, the Netherlands, addresses central questions in the field of American Studies: How does one explain the discrepancy between the promise of American democracy and the disco..

Eric R. Schlereth, An Age of Infidels: The Politics of Religious Controversy in the Early United States.

This book could be summarized in two words “ideas matter,” or by quoting the concluding sentence: “The story of religious controversy in the early republic thus describes the origins of cultural politics in the United States” (241). Eric R. Schlereth, assistant professor of history at the University of Texas in Dallas, focuses his attention on the public debate about the (in)desirability of letting religious authority function in the shaping of a political culture which took place in lectures..