Inherent Dissipation of Upwind‐Biased Potential Temperature Advection and its Feedback on Model Dynamics

Higher order upwind-biased advection schemes are often used for potential temperature advection in dynamical cores of atmospheric models. The inherent diffusive and antidiffusive fluxes are interpreted here as the effect of irreversible sub-gridscale dynamics. For those, total energy conservation and positive internal entropy production must be guaranteed. As a consequence of energy conservation, the pressure gradient term should be formulated in Exner pressure form. The presence of local antidiffusive fluxes in potential temperature advection schemes foils the validity of the second law of thermodynamics. Due to this failure, a spurious wind acceleration into the wrong direction is locally induced via the pressure gradient term. When correcting the advection scheme to be more entropically consistent, the spurious acceleration is avoided, but two side effects come to the fore: (i) the overall accuracy of the advection scheme decreases and (ii) the now purely diffusive fluxes become more discontinuous compared to the original ones, which leads to more sudden body forces in the momentum equation. Therefore, the amplitudes of excited gravity waves from jets and fronts increase compared to the original formulation with inherent local antidiffusive fluxes. The means used for supporting the argumentation line are theoretical arguments concerning total energy conservation and internal entropy production, pure advection tests, one-dimensional advection-dynamics interaction tests and evaluation of runs with a global atmospheric dry dynamical core

Deviations from a general nonlinear wind balance: Local and zonal-mean perspectives

The paper introduces the active wind as the deviation from a general local wind balance, the inactive wind. The inactive wind is directed along intersection lines of Bernoulli function and potential temperature surfaces. In climatological steady state, the inactive mass flux cannot participate in net-mass fluxes, because the mean position of the mentioned intersection lines does not change. A conceptual proximity of the zonal-mean active wind to the residual wind as occurring in the transformed Eulerian mean equations suggests itself. The zonaland time-mean active wind is compared to the residual wind for the Held-Suarez test case. Similarities occur for the meridional components in the zone of Rossby wave breaking in the upper troposphere equatorward of the jet. The vertical components are similar, too. However, the vertical active wind is much stronger in the baroclinic zone. This is due to the missing vertical eddy flux of Ertel's potential vorticity (EPV) in the TEM equations. The largest differences are to be found in the boundary layer, where the active wind exhibits typical pattern of Ekman dynamics. Instantaneous active wind vectors demonstrate mass-inflow for lows and mass-outflow for highs in the boundary layer. An active meridional wind is associated with a filamentation of EPV in the zone of Rossby wave breaking in about 300 hPa. Strong gradients of EPV act as a transport barrier

Co-silencing of human Bub3 and dynein highlights an antagonistic relationship in regulating kinetochore-microtubule attachments

We previously reported that the spindle assembly checkpoint protein Bub3 is involved in regulating kinetochore-microtubule (KT-MT) attachments. Also, Bub3 was reported to interact with the microtubule motor protein dynein. Here we examined how this interaction contributes to KT-MT attachments. Depletion of Bub3 or dynein induced misaligned chromosomes, consistent with their role in KT-MT attachments. Unexpectedly, co-silencing of both proteins partially suppressed the misalignment phenotype and restored chromosome congression. Consistent with these observations, KT-MT attachments in co-depleted cells were stable, able to drive chromosome congression, and produce inter-and intra-kinetochore stretch, indicating they are functional. We suggest that a mutual antagonism exists between Bub3 and dynein to ensure optimal KT-MT attachments. (C) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.CESPU [02-GCQF-CICS-2011N]; FCT - Fundacao para a Ciencia e a Tecnologia [CEQUIMED-PEst-OE/SAU/UI4040/2014]; FCT [SFRH/BD/90744/2012]info:eu-repo/semantics/publishedVersio

AGAPETA ZOEGANA (L.) (LEPIDOPTERA: COCHYLIDAE), A SUITABLE PROSPECT FOR BIOLOGICAL CONTROL OF SPOTTED AND DIFFUSE KNAPWEED, CENTAUREA MACULOSA MONNET DE LA MARCK AND CENTAUREA DIFFUSA MONNET DE LA MARCK (COMPOSITAE) IN NORTH AMERICA

The taxonomy, distribution, life history, and host plant relationships of the cochylid moth Agapeta zoegana (L.), an oligophagous, facultatively multivoltine root feeder, are discussed. The results of oviposition and larval feeding tests with 56 plant species in five families are presented and show that A. zoegana is restricted to a few closely related species of Centaurea. In Europe the moth is widely distributed and abundant in the majority of the root-feeding guilds of Centaurea maculosa Monnet de la Marck studied, with densities of 23.6 larvae per 100 roots in eastern Austria/northwestern Hungary and less than 8 larvae per 100 roots in central Hungary and the Alsace. The acceptance of target North American species (the tetraploid form of C. maculosa and the diploid Centaurea diffusa Monnet de la Marck), the damage caused, and the active searching ability rate A. zoegana as a potentially effective natural enemy of spotted and diffuse knapweed in North America. Agapeta zoegana will be especially promising as it predominantly attacks the rosette, which is, according to a recently developed population model for diffuse knapweed in Canada, the most sensitive stage determining equilibrium knapweed density. Agapeta zoegana is compatible with Pelochrista medullana Staudinger (Lepidoptera: Cochylidae), another knapweed root feeder recently introduced into North America, and will complement the seed-feeding species already established. The moth was approved for release in Canada and the USA and has been established in British Columbia since 1984 on C. diffus

Regulating cellular oxygen sensing by hydroxylation

Oxygen homeostasis under conditions of limited O2 supply requires hypoxia-dependent gene regulation. The transcription factor complex hypoxia-inducible factor 1 (HIF-1) has been recognized as the master regulator that mediates the adaptational genetic response to ensure restoration of energy supply. This review will focus on the recent advances in understanding the hypoxia-induced cellular response with particular respect to cellular O2 sensing for adequate control of HIF-1 activatio

Pivotal Role of Reduced Glutathione in Oxygen-induced Regulation of the Na + /K + Pump in Mouse Erythrocyte Membranes

This study addresses the mechanisms of oxygen-induced regulation of ion transport pathways in mouse erythrocyte, specifically focusing on the role of cellular redox state and ATP levels. Mouse erythrocytes possess Na+/K+ pump, K+-Cl− and Na+-K+-2Cl− cotransporters that have been shown to be potential targets of oxygen. The activity of neither cotransporter changed in response to hypoxia-reoxygenation. In contrast, the Na+/K+ pump responded to hypoxic treatment with reversible inhibition. Hypoxia-induced inhibition was abolished in Na+-loaded cells, revealing no effect of O2 on the maximal operation rate of the pump. Notably, the inhibitory effect of hypoxia was not followed by changes in cellular ATP levels. Hypoxic exposure did, however, lead to a rapid increase in cellular glutathione (GSH) levels. Decreasing GSH to normoxic levels under hypoxic conditions abolished hypoxia-induced inhibition of the pump. Furthermore, GSH added to the incubation medium was able to mimic hypoxia-induced inhibition. Taken together these data suggest a pivotal role of intracellular GSH in oxygen-induced modulation of the Na+/K+ pump activit

Quantum Dissipative Dynamics of the Magnetic Resonance Force Microscope in the Single-Spin Detection Limit

We study a model of a magnetic resonance force microscope (MRFM) based on the cyclic adiabatic inversion technique as a high-resolution tool to detect single electron spins. We investigate the quantum dynamics of spin and cantilever in the presence of coupling to an environment. To obtain the reduced dynamics of the combined system of spin and cantilever, we use the Feynman-Vernon influence functional and get results valid at any temperature as well as at arbitrary system-bath coupling strength. We propose that the MRFM can be used as a quantum measurement device, i.e., not only to detect the modulus of the spin but also its direction

Myoglobin in Brown Adipose Tissue: A Multifaceted Player in Thermogenesis

Brown adipose tissue (BAT) plays an important role in energy homeostasis by generating heat from chemical energy via uncoupled oxidative phosphorylation. Besides its high mitochondrial content and its exclusive expression of the uncoupling protein 1, another key feature of BAT is the high expression of myoglobin (MB), a heme-containing protein that typically binds oxygen, thereby facilitating the diffusion of the gas from cell membranes to mitochondria of muscle cells. In addition, MB also modulates nitric oxide (NO•) pools and can bind C16 and C18 fatty acids, which indicates a role in lipid metabolism. Recent studies in humans and mice implicated MB present in BAT in the regulation of lipid droplet morphology and fatty acid shuttling and composition, as well as mitochondrial oxidative metabolism. These functions suggest that MB plays an essential role in BAT energy metabolism and thermogenesis. In this review, we will discuss in detail the possible physiological roles played by MB in BAT thermogenesis along with the potential underlying molecular mechanisms and focus on the question of how BAT–MB expression is regulated and, in turn, how this globin regulates mitochondrial, lipid, and NO• metabolism. Finally, we present potential MB-mediated approaches to augment energy metabolism, which ultimately could help tackle different metabolic disorders

Non-Markoffian effects of a simple nonlinear bath

We analyze a model of a nonlinear bath consisting of a single two-level system coupled to a linear bath (a classical noise force in the limit considered here). This allows us to study the effects of a nonlinear, non-Markoffian bath in a particularly simple situation. We analyze the effects of this bath onto the dynamics of a spin by calculating the decay of the equilibrium correlator of the spin's z-component. The exact results are compared with those obtained using three commonly used approximations: a Markoffian master equation for the spin dynamics, a weak-coupling approximation, and the substitution of a linear bath for the original nonlinear bath.Comment: 7 pages, 6 figure