Estimating interchannel observation-error correlations for IASI radiance data in the Met Office system

The optimal utilisation of hyper-spectral satellite observations in numerical weather prediction is often inhibited by incorrectly assuming independent interchannel observation errors. However, in order to represent these observation-error covariance structures, an accurate knowledge of the true variances and correlations is needed. This structure is likely to vary with observation type and assimilation system. The work in this article presents the initial results for the estimation of IASI interchannel observation-error correlations when the data are processed in the Met Office one-dimensional (1D-Var) and four-dimensional (4D-Var) variational assimilation systems. The method used to calculate the observation errors is a post-analysis diagnostic which utilises the background and analysis departures from the two systems. The results show significant differences in the source and structure of the observation errors when processed in the two different assimilation systems, but also highlight some common features. When the observations are processed in 1D-Var, the diagnosed error variances are approximately half the size of the error variances used in the current operational system and are very close in size to the instrument noise, suggesting that this is the main source of error. The errors contain no consistent correlations, with the exception of a handful of spectrally close channels. When the observations are processed in 4D-Var, we again find that the observation errors are being overestimated operationally, but the overestimation is significantly larger for many channels. In contrast to 1D-Var, the diagnosed error variances are often larger than the instrument noise in 4D-Var. It is postulated that horizontal errors of representation, not seen in 1D-Var, are a significant contributor to the overall error here. Finally, observation errors diagnosed from 4D-Var are found to contain strong, consistent correlation structures for channels sensitive to water vapour and surface properties.

Hyperbranched polymers containing oxazoline monomers andsuccinic anhydride: applications in fast drying, low solvent coating formulations

tMelt-polycondensation of succinic acid anhydride with oxazoline-based diol monomers gave hyper-branched polymers with carboxylicacids terminal groups.1H NMR and quantitative13C NMRspectroscopy coupled with DEPT-13513C NMR experiment showed high degrees of branching (over 60%).Esterification of the acid end groups by addition of citronellol at 160◦C produced novel white spirit solubleresins which were characterized by Fourier transform-infrared (FTIR) spectroscopy, gel permeation chro-matography (GPC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Blendsof the new hyperbranched materials with commercial alkyd resins resulted in a dramatic, concentrationdependent drop in viscosity. Solvent-borne coatings were formulated containing the hyperbranchedpolymers. Dynamic mechanical analysis studies revealed that the air drying rates of the new coatingsystems were enhanced compared with identical formulations containing only commercial alkyd resins.

Diallyl disulfide-induced apoptosis in a breast-cancer cell line (MCF-7) may be caused by inhibition of histone de-acetylation

The health benefits of garlic have been proven by epidemiological and experimental studies. Diallyl disulphide (DADS), the major organosulfur compound found in garlic oil, is known to lower the incidence of breast cancer both in vitro and in vivo. The studies reported here demonstrate that DADS induces apoptosis in the MCF-7 breast-cancer cell line through interfering with cell-cycle growth phases in a way that increases the sub-G0 population and substantially halts DNA synthesis. DADS also induces phosphatidylserine (PS) translocation from the inner to the outer leaflet of the plasma membrane and activates caspase-3. Further studies revealed that DADS modulates the cellular levels of Bax, Bcl-2, Bcl-xL and Bcl-w in a dose-dependent manner, suggesting the involvement of Bcl-2 family proteins in DADS induced apoptosis. Histone deacetylation inhibitors (HDACi) are known to suppress cancer growth and induce apoptosis in cancer cells. Here it is shown that DADS has HDACi properties in MCF-7 cells as it lowers the removal of an acetyl group from an acetylated substrate and induces histone-4 (H4) hyper-acetylation. The data thus indicate that the HDACi properties of DADS may be responsible for the induction of apoptosis in breast cancer cells.

Application of complex extreme learning machine to multiclass classification problems with high dimensionality: a THz spectra classification problem

We extend extreme learning machine (ELM) classifiers to complex Reproducing Kernel Hilbert Spaces (RKHS) where the input/output variables as well as the optimization variables are complex-valued. A new family of classifiers, called complex-valued ELM (CELM) suitable for complex-valued multiple-input–multiple-output processing is introduced. In the proposed method, the associated Lagrangian is computed using induced RKHS kernels, adopting a Wirtinger calculus approach formulated as a constrained optimization problem similarly to the conventional ELM classifier formulation. When training the CELM, the Karush–Khun–Tuker (KKT) theorem is used to solve the dual optimization problem that consists of satisfying simultaneously smallest training error as well as smallest norm of output weights criteria. The proposed formulation also addresses aspects of quaternary classification within a Clifford algebra context. For 2D complex-valued inputs, user-defined complex-coupled hyper-planes divide the classifier input space into four partitions. For 3D complex-valued inputs, the formulation generates three pairs of complex-coupled hyper-planes through orthogonal projections. The six hyper-planes then divide the 3D space into eight partitions. It is shown that the CELM problem formulation is equivalent to solving six real-valued ELM tasks, which are induced by projecting the chosen complex kernel across the different user-defined coordinate planes. A classification example of powdered samples on the basis of their terahertz spectral signatures is used to demonstrate the advantages of the CELM classifiers compared to their SVM counterparts. The proposed classifiers retain the advantages of their ELM counterparts, in that they can perform multiclass classification with lower computational complexity than SVM classifiers. Furthermore, because of their ability to perform classification tasks fast, the proposed formulations are of interest to real-time applications.

Middle and Late Pleistocene humid periods recorded in palaeolake deposits of the Nafud desert, Saudi Arabia

Present climate in the Nafud desert of northern Saudi Arabia is hyper-arid and moisture brought by north-westerly winds scarcely reaches the region. The existence of abundant palaeolake sediments provides evidence for a considerably wetter climate in the past. However, the existing chronological framework of these deposits is solely based on radiocarbon dating of questionable reliability, due to potential post-depositional contamination with younger 14C. By using luminescence dating, we show that the lake deposits were not formed between 40 and 20 ka as suggested previously, but approximately ca 410 ka, 320 ka, 200 ka, 125 ka, and 100 ka ago. All of these humid phases are in good agreement with those recorded in lake sediments and speleothems from southern Arabia. Surprisingly, no Holocene lake deposits were identified. Geological characteristics of the deposits and diatom analysis suggest that a single, perennial lake covered the entire south-western Nafud ca 320 ka ago. In contrast, lakes of the 200 ka, 125 ka, and 100 ka humid intervals were smaller and restricted to interdune depressions of a pre-existing dune relief. The concurrent occurrence of humid phases in the Nafud, southern Arabia and the eastern Mediterranean suggests that moisture in northern Arabia originated either from the Mediterranean due to more frequent frontal depression systems or from stronger Indian monsoon circulation, respectively. However, based on previously published climate model simulations and palaecolimate evidence from central Arabia and the Negev desert, we argue that humid climate conditions in the Nafud were probably caused by a stronger African monsoon and a distinct change in zonal atmospheric circulation.

Queering Philip Roth: homosocial discourse in 'An actor’s life for me', 'Letting go', 'Sabbath’s theater' and the 'American trilogy'

Much has been written on Roth’s representation of masculinity, but this critical discourse has tended to be situated within a heteronormative frame of reference, perhaps because of Roth’s popular reputation as an aggressively heterosexual, libidinous, masculinist, in some versions sexist or even misogynist author. In this essay I argue that Roth’s representation of male sexuality is more complex, ambiguous, and ambivalent than has been generally recognized. Tracing a strong thread of what I call homosocial discourse running through Roth’s oeuvre, I suggest that the series of intimate relationships with other men that many of Roth’s protagonists form are conspicuously couched in this discourse and that a recognition of this ought to reconfigure our sense of the sexual politics of Roth’s career, demonstrating in particular that masculinity in his work is too fluid and dynamic to be accommodated by the conventional binaries of heterosexual and homosexual, feminized Jew and hyper-masculine Gentile, the “ordinary sexual man” and the transgressively desiring male subject.

Proanthocyanidins inhibit Ascaris suum glutathione-S-transferase activity and increase susceptibility of larvae to levamisole and ivermectin in vitro

Proanthocyanidins (PAC) are a class of plant secondary metabolites commonly found in the diet that have shown potential to control gastrointestinal nematode infections. The anti-parasitic mechanism(s) of PAC remain obscure, however the protein-binding properties of PAC suggest that disturbance of key enzyme functions may be a potential mode of action. Glutathione-S-transferases (GSTs) are essential for parasite detoxification and have been investigated as drug and vaccine targets. Here, we show that purified PAC strongly inhibit the activity of both recombinant and native GSTs from the parasitic nematode Ascaris suum. As GSTs are involved in detoxifying xenobiotic substances within the parasite, we hypothesised that this inhibition may render parasites hyper-susceptible to anthelmintic drugs. Migration inhibition assays with A. suum larvae demonstrated that the potency of levamisole (LEV) and ivermectin (IVM) were significantly increased in the presence of PAC purified from pine bark (4.6-fold and 3.2-fold reduction in IC50 value for LEV and IVM, respectively). Synergy analysis revealed that the relationship between PAC and LEV appeared to be synergistic in nature, suggesting a specific enhancement of LEV activity, whilst the relationship between PAC and IVM was additive rather than synergistic, suggesting independent actions. Our results demonstrate that these common dietary compounds may increase the efficacy of synthetic anthelmintic drugs in vitro, and also suggest one possible mechanism for their well-known anti-parasitic activity.