Spectral isolation of naturally reductive metrics on simple Lie groups

We show that within the class of left-invariant naturally reductive metrics $\mathcal{M}_{\operatorname{Nat}}(G)$ on a compact simple Lie group $G$, every metric is spectrally isolated. We also observe that any collection of isospectral compact symmetric spaces is finite; this follows from a somewhat stronger statement involving only a finite part of the spectrum.Comment: 19 pages, new title and abstract, revised introduction, new result demonstrating that any collection of isospectral compact symmetric spaces must be finite, to appear Math Z. (published online Dec. 2009

Review article: MHD wave propagation near coronal null points of magnetic fields

We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfven speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfven wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the Alfven-speed profile. In a $\beta=0$ plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the Alfven wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the Alfven wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, Alfven wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing.Comment: 34 pages, 5 figures, invited review in Space Science Reviews => Note this is a 2011 paper, not a 2010 pape

Muscle glycogen utilisation during Rugby match play: Effects of pre-game carbohydrate

Objectives: Although the physical demands of Rugby League (RL) match-play are well-known, the fuel sources supporting energy-production are poorly understood. We therefore assessed muscle glycogen utilisation and plasma metabolite responses to RL match-play after a relatively high (HCHO) or relatively low CHO (LCHO) diet. Design: Sixteen (mean ± SD age; 18 ± 1 years, body-mass; 88 ± 12 kg, height 180 ± 8 cm) professional players completed a RL match after 36-h consuming a non-isocaloric high carbohydrate (n = 8; 6 g kg day−1) or low carbohydrate (n = 8; 3 g kg day−1) diet. Methods: Muscle biopsies and blood samples were obtained pre- and post-match, alongside external and internal loads quantified using Global Positioning System technology and heart rate, respectively. Data were analysed using effects sizes ±90% CI and magnitude-based inferences. Results: Differences in pre-match muscle glycogen between high and low carbohydrate conditions (449 ± 51 and 444 ± 81 mmol kg−1 d.w.) were unclear. High (243 ± 43 mmol kg−1 d.w.) and low carbohydrate groups (298 ± 130 mmol kg−1 d.w.) were most and very likely reduced post-match, respectively. For both groups, differences in pre-match NEFA and glycerol were unclear, with a most likely increase in NEFA and glycerol post-match. NEFA was likely lower in the high compared with low carbohydrate group post-match (0.95 ± 0.39 mmol l−1 and 1.45 ± 0.51 mmol l−1, respectively), whereas differences between the 2 groups for glycerol were unclear (98.1 ± 33.6 mmol l−1 and 123.1 ± 39.6 mmol l−1) in the high and low carbohydrate groups, respectively. Conclusions: Professional RL players can utilise ∼40% of their muscle glycogen during a competitive match regardless of their carbohydrate consumption in the preceding 36-h

Self-energy-part resummed quark and gluon propagators in a spin-polarized quark matter and generalized Boltzmann equations

We construct perturbative frameworks for studying nonequilibrium spin-polarized quark matter. We employ the closed-time-path formalism and use the gradient approximation in the derivative expansion. After constructing self-energy-part resummed quark and gluon propagators, we formulate two kind of mutually equivalent perturbative frameworks: The first one is formulated on the basis of the initial-particle distribution function, and the second one is formulated on the basis of `` physical''-particle distribution function. In the course of construction of the second framework, the generalized Boltzmann equations and their relatives {\em directly} come out, which describe the evolution of the system. The frameworks are relevant to the study of a magnetic character of quark matters, e.g., possible quark stars.Comment: 57 page

Quantum dynamics and thermalization for out-of-equilibrium phi^4-theory

The quantum time evolution of \phi^4-field theory for a spatially homogeneous system in 2+1 space-time dimensions is investigated numerically for out-of-equilibrium initial conditions on the basis of the Kadanoff-Baym equations including the tadpole and sunset self-energies. Whereas the tadpole self-energy yields a dynamical mass, the sunset self-energy is responsible for dissipation and an equilibration of the system. In particular we address the dynamics of the spectral (`off-shell') distributions of the excited quantum modes and the different phases in the approach to equilibrium described by Kubo-Martin-Schwinger relations for thermal equilibrium states. The investigation explicitly demonstrates that the only translation invariant solutions representing the stationary fixed points of the coupled equation of motions are those of full thermal equilibrium. They agree with those extracted from the time integration of the Kadanoff-Baym equations in the long time limit. Furthermore, a detailed comparison of the full quantum dynamics to more approximate and simple schemes like that of a standard kinetic (on-shell) Boltzmann equation is performed. Our analysis shows that the consistent inclusion of the dynamical spectral function has a significant impact on relaxation phenomena. The different time scales, that are involved in the dynamical quantum evolution towards a complete thermalized state, are discussed in detail. We find that far off-shell 1 3 processes are responsible for chemical equilibration, which is missed in the Boltzmann limit. Finally, we address briefly the case of (bare) massless fields. For sufficiently large couplings $\lambda$ we observe the onset of Bose condensation, where our scheme within symmetric \phi^4-theory breaks down.Comment: 77 pages, 26 figure

Assessing Big-Bang Nucleosynthesis

Systematic uncertainties in the light-element abundances and their evolution make a rigorous statistical assessment difficult. However, using Bayesian methods we show that the following statement is robust: the predicted and measured abundances are consistent with 95\% credibility only if the baryon-to-photon ratio is between $2\times 10^{-10}$ and $6.5\times 10^{-10}$ and the number of light neutrino species is less than 3.9. Our analysis suggests that the $^4$He abundance may have been systematically underestimated.Comment: 7 pages, LaTeX(2.09), 6 postscript figures (attached). A postscript version with figures can be found at ftp://astro.uchicago.edu/pub/astro/copi/assessing_BBN . (See the README file for details

Excessive growth hormone promotes joint degeneration and chondrocyte metabolic dysfunction in mice

YesMany patients with acromegaly, a hormonal disorder with excessive growth hormone (GH), report pain in joints. The objective of this study is to characterize the joint pathology of mice with over-expression of either bovine GH (bGH) or a GH receptor antagonist (GHa). We also investigate the effect of GH on regulation of chondrocyte cellular metabolism. Knee joints from mice over-expressing bGH or GHa and WT were histologically and μCT analyzed for OA pathologies. Additionally, cartilage from bGH mice was used for metabolomics. Mouse primary chondrocytes from WT or bGH mice with or without Pegvisomant (Peg) treatment were used for Q-PCR and Seahorse Respirometry analysis. Both male and female bGH mice at ~13 months had increased knee joint degeneration, which is characterized by loss of cartilage structure, expansion of hypertrophic chondrocytes, synovitis, and subchondral plate thinning. The joint pathologies were also demonstrated by significantly higher OARSI and Mankin scores in bGH compared with WT mice. Metabolomics revealed changes of a wide range of metabolic pathways in bGH mice including beta-alanine metabolism, tryptophan metabolism, lysine degradation, and ascorbate and aldarate metabolism. Also, bGH chondrocytes upregulated fatty acid oxidation (FAO) and increased expression of Col10a. Joints of GHa mice are remarkably protected from developing age-associated joint degeneration with smooth articular joint surface. These studies uncover that an excessive amount of GH promotes joint degeneration in mice, whereas antagonizing GH action through a GHa protects mice from OA development, which is associated with chondrocyte metabolic dysfunction and hypertrophic changes

Induction of IgG2 and IgG4 B-cell memory following sublingual immunotherapy for ryegrass pollen allergy

Background: While treatment for atopic rhinitis is aimed mostly to relieve symptoms, only allergen-specific immunotherapy (AIT) is targeted to modify the natural history of allergic diseases. This results in sustained clinical tolerance, even when treatment has stopped. The immunomodulatory effects of AIT are attributed mainly to increased regulatory T-cell function and increased allergen-specific IgG4, yet little is known about the effect on the memory B-cell compartment. Objective: We aimed to examine the effects of AIT on the IgE- and IgG subclass-expressing memory B cells. Methods: We recruited 29 patients with atopic seasonal rhinoconjunctivitis and performed a longitudinal analysis of the peripheral immune compartment before, during, and after sublingual immunotherapy (SLIT) for allergy to temperate grass pollen, predominantly to ryegrass pollen (RGP; Lolium perenne). Using flow cytometry on peripheral blood mononuclear cells and serum immunoassays, we analyzed the effects of a 4 months preseasonal treatment regimen comprising two or three courses in consecutive years on circulating IgE+ and IgG+ memory B cells and allergen-specific Ig levels. Results: SLIT increased RGP-specific serum IgG2 and IgG4, as well as the frequencies of IgG2 + and IgG4 + memory B cells, whereas no effect was observed on the IgE+ memory B-cell compartment. Furthermore, SLIT enhanced proportions of regulatory T cells specific to RGP. These changes were associated with clinical improvement. Conclusion: Our data provide evidence for immunological effects of SLIT on B-cell memory. Skewing responses toward IgG2 and IgG4 subclasses might be a mechanism to suppress IgE-mediated allergic responses

Oleate induces K_ATP channel-dependent hyperpolarisation in mouse hypothalamic glucose-excited neurones without altering cellular energy charge

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The unsaturated fatty acid, oleate exhibits anorexigenic properties reducing food intake and hepatic glucose output. However, its mechanism of action in the hypothalamus has not been fully determined. This study investigated the effects of oleate and glucose on GT1-7 mouse hypothalamic cells (a model of glucose-excited (GE) neurons) and mouse arcuate nucleus (ARC) neurons. Whole-cell and perforated patch-clamp recordings, immunoblotting and cell energy status measures were used to investigate oleate- and glucose-sensing properties of mouse hypothalamic neurons. Oleate or lowered glucose concentration caused hyperpolarization and inhibition of firing of GT1-7 cells by the activation of ATP-sensitive K(+) channels (KATP). This effect of oleate was not dependent on fatty acid oxidation or raised AMP-activated protein kinase activity or prevented by the presence of the UCP2 inhibitor genipin. Oleate did not alter intracellular calcium, indicating that CD36/fatty acid translocase may not play a role. However, oleate activation of KATP may require ATP metabolism. The short-chain fatty acid octanoate was unable to replicate the actions of oleate on GT1-7 cells. Although oleate decreased GT1-7 cell mitochondrial membrane potential there was no change in total cellular ATP or ATP/ADP ratios. Perforated patch and whole-cell recordings from mouse hypothalamic slices demonstrated that oleate hyperpolarized a subpopulation of ARC GE neurons by KATP activation. Additionally, in a separate small population of ARC neurons, oleate application or lowered glucose concentration caused membrane depolarization. In conclusion, oleate induces KATP-dependent hyperpolarization and inhibition of firing of a subgroup of GE hypothalamic neurons without altering cellular energy charge.This work was supported by: grants from the Wellcome Trust (grant number 068692) to M.L.J. Ashford; from Juvenile Diabetes Research Foundation (JDRF) to R.J. McCrimmon and Fellowships to C. Beall (JDRF; 3-576-2010 and Diabetes UK 13/0004647

Schuldig landschap. Over de toeristische aantrekkingskracht van Baantjer, Wallander en Inspector Morse

De opnamelokaties van tv-detectives genieten een toenemende populariteit onder toeristen. In dit artikel wordt, op basis van een tekstuele analyse van ‘Baantjer’, ‘Inspector Morse’ en ‘Wallander’, onderzocht welke inhoudelijke kenmerken van deze tv-detectives mogelijk als ‘trigger’ fungeren. Uit de analyse blijkt dat plaats en beweging een centrale rol vervullen binnen de narratieve structuur van dit genre. Door zelf de lokaties te bezoeken, kunnen toeristen het spoor nalopen van hun geliefde detective om aldaar, vanuit een veilige positie, tijdelijk op te gaan in het schemergebied tussen fictie en werkelijkheid