3,157 research outputs found

    Quantized Anomalous Hall Effect in Two-Dimensional Ferromagnets - Quantum Hall Effect from Metal -

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    We study the effect of disorder on the anomalous Hall effect (AHE) in two-dimensional ferromagnets. The topological nature of AHE leads to the integer quantum Hall effect from a metal, i.e., the quantization of σxy\sigma_{xy} induced by the localization except for the few extended states carrying Chern number. Extensive numerical study on a model reveals that Pruisken's two-parameter scaling theory holds even when the system has no gap with the overlapping multibands and without the uniform magnetic field. Therefore the condition for the quantized AHE is given only by the Hall conductivity σxy\sigma_{xy} without the quantum correction, i.e., σxy>e2/(2h)|\sigma_{xy}| > e^2/(2h).Comment: 5 pages, 4 figures, REVTe

    Health and wealth in the Roman Empire

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    Ancient Rome was the largest and most populous empire of its time, and the largest pre-industrial state in European history. Recent though not universally accepted research suggests that at least for the most populous central periods of its history standard of living was also rather higher than before or after. To trace whether this is also reflected in Roman biological standard of living, we present the first large and more or less comprehensive dataset, based on skeletal data for some 10,000 individuals, covering all periods of Roman history, and all regions (even if inevitably unequally). We discuss both the methodologies that we developed and the historical results. Instead of reconstructing heights from the long bones assuming fixed body proportions or from one individual long bone, we apply exploratory factor analysis and calculate factor scores for 50-year periods. Our measure of the biological standard of living declined during the last two centuries B.C. and started to improve again, slowly at first, from the second century A.D. It correlated negatively with population, but also with other aspects of standard of living such as wages or diets

    Anti-inflammatory actions of acupuncture.

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    Acupuncture has a beneficial effect when treating many diseases and painful conditions, and therefore is thought to be useful as a complementary therapy or to replace generally accepted pharmacological intervention. The attributive effect of acupuncture has been investigated in inflammatory diseases, including asthma, rhinitis, inflammatory bowel disease, rheumatoid arthritis, epicondylitis, complex regional pain syndrome type 1 and vasculitis. Large randomised trials demonstrating the immediate and sustained effect of acupuncture are missing. Mechanisms underlying the ascribed immunosuppressive actions of acupuncture are reviewed in this communication. The acupuncture-controlled release of neuropeptides from nerve endings and subsequent vasodilative and anti-inflammatory effects through calcitonine gene-related peptide is hypothesised. The complex interactions with substance P, the analgesic contribution of beta-endorphin and the balance between cell-specific pro-inflammatory and anti-inflammatory cytokines tumour necrosis factor-alpha and interleukin-10 are discussed

    Influence of Ring Contraction on the Electronic Structure of Nickel Tetrapyrrole Complexes: Corrole vs Porphyrin

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    The influence of the contracted corrole macrocycle, in comparison to the larger porphyrin macrocycle, on the electronic structure of nickel was studied with X-ray and ultraviolet photoelectron spectroscopy (XPS, UPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Synthesis and in situ characterization of the Ni complexes of octaethylporphyrin (NiOEP) and hexaethyldimethylcorrole (NiHEDMC) were performed in ultra-high vacuum. XPS and NEXAFS spectra reveal a +2 oxidation state and a low-spin d8 electron configuration of Ni in both complexes, despite the formal trianionic nature of the corrole ligand. UPS, in combination with density functional theory (DFT) calculations, support the electronic structure of a Ni(II) corrole with a π-radical character of the ligand. The NEXAFS spectra also reveal differences in the valence electronic structure, which are attributed to the size mismatch between the small Ni(II) center and the larger central cavity of NiOEP. Analysis of the gas-phase structures shows that the Ni−N bonds in NiOEP are 4%–6% longer than those in NiHEDMC, even when NiOEP adopts a ruffled conformation. The individual interactions that constitute the Ni−ligand bond are altogether stronger in the corrole complex, according to bonding analysis within the energy decomposition analysis and the natural orbitals for chemical valence theory (EDA-NOCV)

    Evidence for local inflammation in complex regional pain syndrome type 1.

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    BACKGROUND: The pathophysiology of complex regional pain syndrome type 1 (CRPS 1) is still a matter of debate. Peripheral afferent, efferent and central mechanisms are supposed. Based on clinical signs and symptoms (e.g. oedema, local temperature changes and chronic pain) local inflammation is suspected. AIM: To determine the involvement of neuropetides, cytokines and eicosanoids as locally formed mediators of inflammation. METHODS: In this study, nine patients with proven CRPS 1 were included. Disease activity and impairment was determined by means of a Visual Analogue Scale, the McGill Pain Questionnaire, the difference in volume and temperature between involved and uninvolved extremities, and the reduction in active range of motion of the involved extremity. Venous blood was sampled from and suction blisters made on the involved and uninvolved extremities for measurement of cytokines interleukin (IL)-6, II-1beta and tumour necrosis factor-alpha (TNF-alpha), the neuropetides NPY and CRGP, and prostaglandin E2RESULTS: The patients included in this study did have a moderate to serious disease activity and impairment. In plasma, no changes of mediators of inflammation were observed. In blister fluid, however, significantly higher levels of IL-6 and TNF-alpha in the involved extremity were observed in comparison with the uninvolved extremity. CONCLUSIONS: This is the first time that involvement of mediators of inflammation in CRPS 1 has been so clearly and directly demonstrated. This observation opens new approaches for the succesful use and development of immunosuppressives in CRPS 1

    Involvement of Mhc Loci in immune responses that are not Ir-gene-controlled

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    Twenty-nine randomly chosen, soluble antigens, many of them highly complex, were used to immunize mice of two strains, C3H and B10.RIII. Lymphnode cells from the immunized mice were restimulated in vitro with the priming antigens and the proliferative response of the cells was determined. Both strains were responders to 28 of 29 antigens. Eight antigens were then used to immunize 11 congenic strains carrying different H-2 haplotypes, and the T-cell proliferative responses of these strains were determined. Again, all the strains responded to seven of the eight antigens. These experiments were then repeated, but this time -antibodies specific for the A (AA) or E (EE) molecules were added to the culture to block the in vitro responsiveness. In all but one of the responses, inhibition with both A-specific and E-specific antibodies was observed. The response to one antigen (Blastoinyces) was exceptional in that some strains were nonresponders to this antigen. Furthermore, the response in the responder strains was blocked with A-specific, but not with E-specific, antibodies. The study demonstrates that responses to antigens not controlled by Irr genes nevertheless require participation of class II Mhc molecules. In contrast to Ir gene-controlled responses involving either the A- or the E-molecule controlling loci (but never both), the responses not Ir-controlled involve participation of both A- and E-controlling loci. The lack of Ir-gene control is probably the result of complexity of the responses to multiple determinants. There is thus no principal difference between responses controlled and those not controlled by Ir genes: both types involve the recognition of the antigen, in the context of Mhc molecules

    Prices of Orphan Drugs in Four Western European Countries Before and After Market Exclusivity Expiry:A Cross-Country Comparison of List Prices and Purchase Prices

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    Background: Increasing pharmaceutical expenditure challenges the sustainability and accessibility of healthcare systems across Europe. Confidentiality restraints hinder assessment of actual prices of Orphan Medicinal Products (OMPs). Hence, we assessed the real prices of brand-name OMPs around market exclusivity expiry (MEE). Objective: We aimed to explore developments in published list prices (LPs) and confidential hospital purchase prices (PPs) of brand-name OMPs relative to their market exclusivity status in Western European countries with similar GDPs. Methods: We analyzed LPs and PPs of 13 selected OMPs purchased by university hospitals in Western European countries between 2000 and 2020. For confidentially reasons, proportions were used, with the Dutch LPs of the selected OMPs at the year of MEE serving as reference values. PPs included pre-purchase discounts. Rebates were not considered. Results: Data were analyzed from hospitals in Denmark (DK) (n = 1), France (FR) (n = 1), Germany (DE) (n = 2), and the Netherlands (NL) (n = 1). Average LPs and PPs of included OMPs dropped gradually but limited over time, with no explicit price drop after MEE. LP levels differed more per country than PP levels: LP range before MEE was 164% (DE)–101% (FR) and after MEE was 135% (DE)–82% (FR); PP range before MEE was 150% (DE)–102% (FR) and after MEE was 107% (DE)–80% (FR). Overall differences between LPs and PPs were &lt; 3% in all countries, except for Denmark. Conclusion: No evident price drops of included brand-name OMPs were observed around MEE and differences in purchase prices are modest in the selected Western European countries. Results were not subject to significance testing. More robust data are needed to strengthen negotiations with suppliers.</p

    The Kondo Box: A Magnetic Impurity in an Ultrasmall Metallic Grain

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    We study the Kondo effect generated by a single magnetic impurity embedded in an ultrasmall metallic grain, to be called a ``Kondo box''. We find that the Kondo resonance is strongly affected when the mean level spacing in the grain becomes larger than the Kondo temperature, in a way that depends on the parity of the number of electrons on the grain. We show that the single-electron tunneling conductance through such a grain features Kondo-induced Fano-type resonances of measurable size, with an anomalous dependence on temperature and level spacing.Comment: 4 Latex pages, 4 figures, submitted to Phys. Rev. Let
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