The stellar thermal wind as a consequence of oblateness

In many rotating fluids, the lowest-order force balance is between gravity, pressure, and rotational acceleration ('GPR' balance). Terrestrial GPR balance takes the form of geostrophy and hydrostasy, which together yield the terrestrial thermal wind equation. By contrast, stellar GPR balance is an oblateness equation, which determines the departures of the thermal variables from spherical symmetry; its curl yields the 'stellar thermal wind equation.' In this sense, the stellar thermal wind should be viewed not as a consequence of geostrophy, but of baroclinicity in the oblateness. Here we treat the full stellar oblateness, including the thermal wind, using pressure coordinates. We derive the generalised stellar thermal wind equation and identify the parameter regime for which it holds. In the case of the Sun, not considering the full oblateness has resulted in conflicting calculations of the theoretical aspherical temperature anomaly. We provide new calculation here and find that the baroclinic anomaly is ~3-60 times smaller than the barotropic anomaly. Thus, the anomaly from the thermal wind may not be measurable helioseismically; but if measurement were possible, this would potentially yield a new way to bracket the depth of the solar tachocline.Comment: 5 pages, accepted for publication in MNRAS

Exploring the Influence of Density Contrast on Solar Near-Surface Shear

The advent of helioseismology has determined in detail the average rotation rate of the Sun as a function of radius and latitude. These data immediately reveal two striking boundary layers of shear in the solar convection zone (CZ): a tachocline at the base, where the differential rotation of the CZ transitions to solid-body rotation in the radiative zone, and a 35-Mm-thick near-surface shear layer (NSSL) at the top, where the rotation rate slows by about 5% with increasing radius. Though asteroseismology cannot probe the differential rotation of distant stars to the same level of detail that helioseismology can achieve for the Sun, it is possible that many cool stars with outer convective envelopes possess similar differential rotation characteristics, including both a tachocline and a NSSL. Here we present the results of 3D global hydrodynamic simulations of spherical-shell convection for a Sun-like star at different levels of density contrast across the shell. The simulations with high stratification possess characteristics of near-surface shear, especially at low latitudes. We discuss in detail the dynamical balance of torques giving rise to the NSSL in our models and interpret what these balances imply for the real Sun. We further discuss the dynamical causes that may serve to wipe out near-surface shear at high latitudes, and conclude by offering some theories as to how this problem might be tackled in future work

Influence of Gut Microbiome on Obesity in Western-Style Dietary Practices Versus Other Diets: A Systematic Review

BACKGROUND: The human gut is home to a microbiome that has a complex relationship to human health. Like the human genome project, microbiome is catching the attention of researchers who seek new methods to combat obesity and negative health outcomes associated with it. OBJECTIVES: This systematic review aims to distinguish the impact of a Western diet on gut health verses a plant-based diet. DATA SOURCES: EBSCOHost library databases inclusive of CINAHL plus, ScienceDirect, and PubMed using keywords to better understand the correlation of dietary practices and microbiome balance. STUDY ELIGIBILITY: Criteria that include diet, current research, and scholarly peer reviewed articles. PARTICIPANTS: Ranged from mice to children and adults. INTERVENTIONS: Trends in intervention practices were inclusive of plant-based diets, probiotic use with complimentary prebiotic intake. Research trends away from the Western diet and leans more toward the Mediterranean diet that is high fiber to encourage a diverse microbiome. STUDY APPRAISAL AND SYNTHESIS METHODS: Studies were selectively compared based on diet type and outcome measures. RESULTS: The 39 articles relevant to diet intervention studies on microbiome show decreased risk for obesity when not Westernized. LIMITATIONS: Studies are currently conducted on mice and in small populations. Most of studies were based in the U.S., so a weak international connection was noted. CONCLUSIONS AND IMPLICATIONS: Understanding disease processes associated with variations in microbiome can help researchers target interventions to maintain positive health status. Future research inclusive of diet practices will be valuable in understanding how to improve microbiome to maintain health

Hydrogen Atom Transfer (HAT)-Triggered Iron-Catalyzed Intra- and Intermolecular Coupling of Alkenes with Hydrazones: Access to Complex Amines

A methodology for the coupling of alkenes with aldehyde- or ketone-derived Cbz-hydrazones to form a new C−C bond through a radical process is described. The sequence comprises an initial in situ generation of a putative iron hydride followed by a hydrogen atom transfer to an alkene, a coupling with a hydrazone, and a final reduction of the nitrogen-centered radical. Hydrogenation of the obtained hydrazines renders amines, including valuable tert-alkyl amines. KEYWORDS: HAT, iron catalysis, α-tert-amines, C−C bond formation, radical processes, synthetic method

Upper respiratory tract infections and general anaesthesia in children

Conflicting reports regarding the hazards of anaesthesia in children presenting for surgery with an upper respiratory tract infection have appeared in the literature. In the present study 130 children undergoing general anaesthesia with face mask for myringotomy and grommet insertion were graded as having either an acute or recent upper respiratory tract infection or were asymptomatic according to predetermined clinical symptoms and signs. The severity of respiratory and related complications were scored during induction, emergence and recovery. The peripheral oxygen saturation was recorded during induction, emergence, transfer to the recovery ward and in the recovery ward itself. There were no significant differences (p > 0.05) in the complication scores between the three groups of children. However, the incidence of hypoxaemia (oxygen saturation ± 93%) was significantly greater during transfer in the acute infection group (p = 0.001) and the recent infection group (p = 0.02), as well as during recovery in the acute group (p = 0.03) compared with asymptomatic children.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75689/1/j.1365-2044.1992.tb02389.x.pd

Observation of exchange Coulomb interactions in the quantum Hall state at nu=3

Coulomb exchange interactions of electrons in the nu=3 quantum Hall state are determined from two inter-Landau level spin-flip excitations measured by resonant inelastic light scattering. The two coupled collective excitations are linked to inter-Landau level spin-flip transitions arising from the N=0 and N=1 Landau levels. The strong repulsion between the two spin-flip modes in the long-wave limit is clearly manifested in spectra displaying Coulomb exchange contributions that are comparable to the exchange energy for the quantum Hall state at nu=1. Theoretical calculations within the Hartree-Fock approximation are in a good agreement with measured energies of spin-flip collective excitations.Comment: 5 pages, 3 figures, to appear in PRB Rapid Communication