46 research outputs found

    Some Results of Mathematical Modeling of the International Market for Emissions Permits

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    The emphasis is on results of a numerical analysis performed for a simplified dynamical model of the international market for greenhouse gases emissions permits, which is one of the Kyoto flexible mechanisms. For the model, an optimal control problem is formulated, and a procedure for constructing optimal strategies of Russias behavior is suggested. A possibility of obtaining algorithms input data from different integrated assessment models is discussed

    Quantum impurity solvers using a slave rotor representation

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    We introduce a representation of electron operators as a product of a spin-carry ing fermion and of a phase variable dual to the total charge (slave quantum rotor). Based on this representation, a new method is proposed for solving multi-orbital Anderson quantum impurity models at finite interaction strength U. It consists in a set of coupled integral equations for the auxiliary field Green's functions, which can be derived from a controlled saddle-point in the limit of a large number of field components. In contrast to some finite-U extensions of the non-crossing approximation, the new method provides a smooth interpolation between the atomic limit and the weak-coupling limit, and does not display violation of causality at low-frequency. We demonstrate that this impurity solver can be applied in the context of Dynamical Mean-Field Theory, at or close to half-filling. Good agreement with established results on the Mott transition is found, and large values of the orbital degeneracy can be investigated at low computational cost.Comment: 18 pages, 15 figure

    Electronic correlation in the infrared optical properties of the quasi two dimensional Îș\kappa-type BEDT-TTF dimer system

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    The polarized optical reflectance spectra of the quasi two dimensional organic correlated electron system Îș\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]YY, Y=Y = Br and Cl are measured in the infrared region. The former shows the superconductivity at Tc≃T_{\rm c} \simeq 11.6 K and the latter does the antiferromagnetic insulator transition at TN≃T_{\rm N} \simeq 28 K. Both the specific molecular vibration mode Îœ3(ag)\nu_{3}(a_{g}) of the BEDT-TTF molecule and the optical conductivity hump in the mid-infrared region change correlatively at T∗≃T^{*} \simeq 38 K of Îș\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Br, although no indication of T∗T^{*} but the insulating behaviour below Tins≃T_{\rm ins} \simeq 50-60 K are found in Îș\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Cl. The results suggest that the electron-molecular vibration coupling on the Îœ3(ag)\nu_{3}(a_{g}) mode becomes weak due to the enhancement of the itinerant nature of the carriers on the dimer of the BEDT-TTF molecules below T∗T^{*}, while it does strong below TinsT_{\rm ins} because of the localized carriers on the dimer. These changes are in agreement with the reduction and the enhancement of the mid-infrared conductivity hump below T∗T^{*} and TinsT_{\rm ins}, respectively, which originates from the transitions between the upper and lower Mott-Hubbard bands. The present observations demonstrate that two different metallic states of Îș\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Br are regarded as {\it a correlated good metal} below T∗T^{*} including the superconducting state and {\it a half filling bad metal} above T∗T^{*}. In contrast the insulating state of Îș\kappa-(BEDT-TTF)2_{2}Cu[N(CN)2_{2}]Cl below TinsT_{\rm ins} is the Mott insulator.Comment: 8 pages, 7 figure

    Worldwide diversity of endophytic fungi and insects associated with dormant tree twigs

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    International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm genera, from 51 locations in 32 countries worldwide. Endophytic fungi were characterized by high-throughput sequencing of 352 samples from 145 tree species in 28 countries. Insects were reared from 227 samples of 109 tree species in 18 countries and sorted into taxonomic orders and feeding guilds. Herbivorous insects were grouped into morphospecies and were identified using molecular and morphological approaches. This dataset reveals the diversity of tree-associated taxa, as it contains 12,721 fungal Amplicon Sequence Variants and 208 herbivorous insect morphospecies, sampled across broad geographic and climatic gradients and for many tree species. This dataset will facilitate applied and fundamental studies on the distribution of fungal endophytes and insects in trees

    Autoantibodies against type I IFNs in patients with life-threatening COVID-19

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    Interindividual clinical variability in the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is vast. We report that at least 101 of 987 patients with life-threatening coronavirus disease 2019 (COVID-19) pneumonia had neutralizing immunoglobulin G (IgG) autoantibodies (auto-Abs) against interferon-w (IFN-w) (13 patients), against the 13 types of IFN-a (36), or against both (52) at the onset of critical disease; a few also had auto-Abs against the other three type I IFNs. The auto-Abs neutralize the ability of the corresponding type I IFNs to block SARS-CoV-2 infection in vitro. These auto-Abs were not found in 663 individuals with asymptomatic or mild SARS-CoV-2 infection and were present in only 4 of 1227 healthy individuals. Patients with auto-Abs were aged 25 to 87 years and 95 of the 101 were men. A B cell autoimmune phenocopy of inborn errors of type I IFN immunity accounts for life-threatening COVID-19 pneumonia in at least 2.6% of women and 12.5% of men

    Immunoreactive alpha-MSH and ACTH levels in rat plasma and pituitary.

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    A radioimmunoassay is described for the measurement of alpha-melanocyte-stimulating hormone (alpha-MSH). The antibody was produced in rabbits by immunization with alpha-MSH coupled to bovine serum albumin with carbodiimide. The antibody did not react significantly with ACTH, beta-MSH, or 6 fragments of ACTH. The sensitivity and reliability of the assay were improved by employing a simple plasma extraction procedure. When applied to a 2 ml plasma sample, the detection limit of the radioimmunoassay was 6 pg/ml. ACTH was measured with a sensitive and specific radioimmunoassay previously described for humans and adapted for the rat. The anti-ACTH serum cross-reacted with the biologically active portion of alpha-p ACTH and not with alpha-MSH, beta-MSH or the alpha-p 17-39 and alpha-p 25-39 fragments of ACTH. The detection limit was 20 pg/ml. Plasma and pituitary alpha-MSH and ACTH had the same immunoreactivity as synthetic alpha-MSH and ACTH. alpha-MSH and ACTH contents of the rat neurointermediate lobe were 1398 +/- 360 (SE) ng and 28.2 +/- 2.9 ng, respectively, while in the anterior lobe they were 102 +/- 31 ng and 551 +/- 36 ng, respectively. The plasma alpha-MSH concentration at 8 AM in male rats was 64 +/- 8 pg/ml when the plasma ACTH concentration was 92 +/- 15 pg/ml. Over a 24-hour period two peaks of plasma alpha-MSH were observed, one at 4 AM (142 +/- 35 pg/ml) and the other at 4 PM (139 +/- 26 pg/ml). Plasma ACTH was higher at noon (151 +/- 43 pg/ml) and 4 PM (130 +/- 48 pg/ml). Short-term exposure to ether induced a transient increase in alpha-MSH level 5 min later and a rapid return to normal levels. Plasma ACTH increased significantly 2.5 min after the onset of ether stress and remained high for 30 min. Two hours' exposure to ether did not change plasma alpha-MSH, although a 3-fold increase in plasma ACTH was observed. Haloperidol injection was followed by a large increase in plasma alpha-MSH, whereas ACTH levels increased similarly after saline and Haloperidol injection. Corticoid administration reduced ACTH, but not alpha-MSH. Three weeks after adrenalectomy, alpha-MSH levels had not changed but ACTH levels had increased ten-fold. These data indicate that alpha-MSH is secreted in the rat, and that the regulation of its secretion is different from that of ACTH
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