The climatology of the middle atmosphere in a vertically extended version of the Met Office's climate model. Part I: mean state

The climatology of a stratosphere-resolving version of the Met Office’s climate model is studied and validated against ECMWF reanalysis data. Ensemble integrations are carried out at two different horizontal resolutions. Along with a realistic climatology and annual cycle in zonal mean zonal wind and temperature, several physical effects are noted in the model. The time of final warming of the winter polar vortex is found to descend monotonically in the Southern Hemisphere, as would be expected for purely radiative forcing. In the Northern Hemisphere, however, the time of final warming is driven largely by dynamical effects in the lower stratosphere and radiative effects in the upper stratosphere, leading to the earliest transition to westward winds being seen in the midstratosphere. A realistic annual cycle in stratospheric water vapor concentrations—the tropical “tape recorder”—is captured. Tropical variability in the zonal mean zonal wind is found to be in better agreement with the reanalysis for the model run at higher horizontal resolution because the simulated quasi-biennial oscillation has a more realistic amplitude. Unexpectedly, variability in the extratropics becomes less realistic under increased resolution because of reduced resolved wave drag and increased orographic gravity wave drag. Overall, the differences in climatology between the simulations at high and moderate horizontal resolution are found to be small.

Insulin, glucagon-like peptide 1, glucose-dependent insulinotropic polypeptide and insulin-like growth factor I as putative mediators of the hypolipidemic effect of oligofructose in rats

The addition of oligofructose as a dietary fiber decreases the serum concentration and the hepatic release of VLDL-triglycerides in rats. Because glucose, insulin, insulin-like growth factor I (IGF-I) and gut peptides [i.e., glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1)]) are factors involved in the metabolic response to nutrients, this paper analyzes their putative role in the hypolipidemic effect of oligofructose. Male Wistar rats were fed a nonpurified diet with or without 10% oligofructose for 30 d. Glucose, insulin, IGF-I and GIP concentrations were measured in the serum of rats after eating. GIP and GLP-1 contents were also assayed in small intestine and cecal extracts, respectively. A glucose tolerance test was performed in food-deprived rats. Serum insulin level was significantly lower in oligofructose-fed rats both after eating and in the glucose tolerance test, whereas glycemia was lower only in the postprandial state. IGF-I serum level did not differ between groups. GIP concentration was significantly higher in the serum of oligofructose-fed rats. The GLP-1 cecal pool was also significantly higher. In this study, we have shown that cecal proliferation induced by oligofructose leads to an increase in GLP-1 concentration. This latter incretin could be involved in the maintenance of glycemia despite a lower insulinemia in the glucose tolerance test in oligofructose-fed rats. We discuss also the role of hormonal changes in the antilipogenic effect of oligofructose.

I and I: immunity to error through misidentification of the subject

Abstract I argue for the following claims: [1] all uses of I (the word ‘I’ or thought-element I) are absolutely immune to error through misidentification relative to I. [2] no genuine use of I can fail to refer. Nevertheless [3] I isn’t univocal: it doesn’t always refer to the same thing, or kind of thing, even in the thought or speech of a single person. This is so even though [4] I always refers to its user, the subject of experience who speaks or thinks, and although [5] if I’m thinking about something specifically as myself, I can’t fail to be thinking of myself, and although [6] a genuine understanding use of I always involves the subject thinking of itself as itself, whatever else it does or doesn’t involve, and although [7] if I take myself to be thinking about myself, then I am thinking about myself.

Anisotropic refinement of the structure of Thermoascus aurantiacusxylanase I

The isotropic crystallographic model of the structure of xylanase I from Thermoascus aurantiacus (TAXI) has now been refined anisotropically at 1.14 Å resolution to a standard residual of R = 11.1% for all data. TAXI is amongst the five largest proteins deposited in the Protein Data Bank to have been refined with anisotropic displacement parameters (ADPs) at this level of resolution. The anisotropy analysis revealed a more isotropic distribution of anisotropy than usually observed previously. Adding ADPs resulted in high-quality electron-density maps which revealed discrepancies from the previously suggested primary sequences for this enzyme. Side-chain conformational disorder was modelled for 16 residues, including Trp275, a bulky residue at the active site. An unrestrained refinement was consistent with the protonation of the catalytic acid/base glutamate and the deprotonation of the nucleophile glutamate, as required for catalysis. The thermal stability of TAXI is reinterpreted in the light of the new refined model.

Synthesis and X-ray crystal structure of the copper(I) dicarboxylic acid complex [Cu(η1-bdoaH)(PPh3)3] (bdoaH2 = benzene-1,2- dioxyacetic acid)

The copper(II) complex [Cu(bdoa)(H2O)2] (bdoaH2 = benzene-1,2-dioxyacetic acid) reacts with triphenylphosphine (1:4 mol ratio) to give the colourless copper(I) complex [Cu(η1-bdoaH)(PPh3)3] (1) in good yield. The X-ray crystal structure of the complex shows the copper atom at the centre of a distorted tetrahedron, and is ligated by the phosphorus atoms of the three triphenylphosphines and one carboxylate oxygen atom of the bdoaH− ligand. Significant intermolecular hydrogen-bonding exists between the pendant carboxylate OH function of one molecule and the uncoordinated “ketonic” oxygen of a neighbouring molecule. Complex 1 is non-conducting in chloroform but ionizes readily in acetonitrile. The cyclic voltammogram of an acetonitrile solution of 1 shows a single irreversible anodic peak for the oxidation of the PPh3 ligands and the copper(I) centre, and a single irreversible cathodic peak for the reduction of the bdoaH− ion. IR and mass spectral data for 1 are given.

Amphioxus type I keratin cDNA and the evolution of intermediate filament genes

We report the cloning of an intermediate filament (IF) cDNA from the cephalochordate amphioxus that encodes a protein assignable to the type I keratin group. This is the first type I keratin reported from an invertebrate. Molecular phylogenetic analyses reveal that amphioxus also possesses a type II keratin, and that the genes encoding short-rod IF proteins underwent different patterns of duplication in vertebrates and their closest relatives, the cephalochordates. Extensive IF gene duplication and divergence may have facilitated the origin of new specialised cell types in vertebrates.

Precise calculations of the existence of multiple AMOC equilibria in coupled climate models Part I: equilibrium states

This study examines criteria for the existence of two stable states of the Atlantic Meridional Overturning Circulation (AMOC) using a combination of theory and simulations from a numerical coupled atmosphere–ocean climate model. By formulating a simple collection of state parameters and their relationships, the authors reconstruct the North Atlantic Deep Water (NADW) OFF state behavior under a varying external salt-flux forcing. This part (Part I) of the paper examines the steady-state solution, which gives insight into the mechanisms that sustain the NADW OFF state in this coupled model; Part II deals with the transient behavior predicted by the evolution equation. The nonlinear behavior of the Antarctic Intermediate Water (AAIW) reverse cell is critical to the OFF state. Higher Atlantic salinity leads both to a reduced AAIW reverse cell and to a greater vertical salinity gradient in the South Atlantic. The former tends to reduce Atlantic salt export to the Southern Ocean, while the latter tends to increases it. These competing effects produce a nonlinear response of Atlantic salinity and salt export to salt forcing, and the existence of maxima in these quantities. Thus the authors obtain a natural and accurate analytical saddle-node condition for the maximal surface salt flux for which a NADW OFF state exists. By contrast, the bistability indicator proposed by De Vries and Weber does not generally work in this model. It is applicable only when the effect of the AAIW reverse cell on the Atlantic salt budget is weak.