1,309 research outputs found

    Ab initio GW many-body effects in graphene

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    We present an {\it ab initio} many-body GW calculation of the self-energy, the quasiparticle band plot and the spectral functions in free-standing undoped graphene. With respect to other approaches, we numerically take into account the full ionic and electronic structure of real graphene and we introduce electron-electron interaction and correlation effects from first principles. Both non-hermitian and also dynamical components of the self-energy are fully taken into account. With respect to DFT-LDA, the Fermi velocity is substantially renormalized and raised by a 17%, in better agreement with magnetotransport experiments. Furthermore, close to the Dirac point the linear dispersion is modified by the presence of a kink, as observed in ARPES experiments. Our calculations show that the kink is due to low-energy ππ\pi \to \pi^* single-particle excitations and to the π\pi plasmon. Finally, the GW self-energy does not open the band gap.Comment: 5 pages, 4 figures, 1 tabl

    Matter waves in a gravitational field: An index of refraction for massive particles in general relativity

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    We consider the propagation of massive-particle de Broglie waves in a static, isotropic metric in general relativity. We demonstrate the existence of an index of refraction that governs the waves and that has all the properties of a classical index of refraction. We confirm our interpretation with a WKB solution of the general-relativistic Klein-Gordon equation. Finally, we make some observations on the significance of the optical action.Comment: 20 pages, latex, ps and pdf. To appear in Am.J.Phys September, 200

    Synthetic cathinones related fatalities: an update

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    Synthetic cathinones, more commonly known as "bath salts", are synthetic drugs chemically related to cathinone, a psychostimulant found in the khat plant. They are the first most consumed products among new psychoactive substances, which cause psychostimulant and hallucinogenic effects determining a number of fatalities worldwide.  In this paper, we have systematically reviewed cases of synthetic cathinones-related fatalities analytically confirmed, which have occurred in the last few years.OBJECTIVE: Synthetic cathinones, more commonly known as “bath salts”, are synthetic drugs chemically related to cathinone, a psychostimulant found in the khat plant. They are the first most consumed products among new psychoactive substances, which cause psychostimulant and hallucinogenic effects determining a number of fatalities worldwide. In this paper, we have systematically reviewed cases of synthetic cathinones-related fatalities analytically confirmed, which have occurred in the last few years. MATERIALS AND METHODS: Relevant scientific articles were identified in Medline, Cochrane Central, Scopus, Web of Science and Institutional/ government websites up to November 2017 using the following keywords: synthetic cathinones, mephedrone, methylenedioxypyrovalerone, MDPV, methylone, ethylone, buthylone, fatal intoxication, fatalities and death. RESULTS: In total, 20 citations met the criteria for inclusion, representing several fatal cases with analytically confirmed synthetic cathinones in biological sample/s of the deceased. The death was attributed to hyperthermia, hypertension, cardiac arrest and more in general to the classic serotonin syndrome. Only rarely did the concentration of the parent drug causing fatality overcome the value of 1 mg/L in post-mortem biological fluids. CONCLUSIONS: Abuse of synthetic cathinones still represents a serious public health issue. Systematic clinical studies on both the animal and human model are lacking; therefore, the only available data are from the users who experience the possible hazardous consequences. Analytical methodologies for the identification of parent compounds and eventual metabolites both in ante-mortem and post-mortem cases need to be developed and validated. Analytical data should be shared through different communication platforms with the aim of stopping this serious health threat for drug users

    pyGOMoDo: GPCRs modeling and docking with python

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    Motivation We present pyGOMoDo, a Python library to perform homology modeling and docking, specifically designed for human GPCRs. pyGOMoDo is a python wrap-up of the updated functionalities of GOMoDo web server (). It was developed having in mind its usage through Jupyter notebooks, where users can create their own protocols of modeling and docking of GPCRs. In this article, we focus on the internal structure and general capabilities of pyGOMoDO and on how it can be useful for carrying out structural biology studies of GPCRs.Results The source code is freely available at under the Apache 2.0 license. Tutorial notebooks containing minimal working examples can be found at

    Suitability of miRNA assessment in postmortem interval estimation

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    OBJECTIVE: The aim of this review was to explore recent pieces of evidence focused on the use of miRNAs for PMI estimation both in humans and animal experiments, with particular interest on the best miRNAs to use as reference/target markers in different tissues or biological fluids. MiRNAs are innovative biomarkers used in clinical and research field: they appear very attractive, being introduced in forensic research scenarios even for PMI estimation.MATERIALS AND METHODS: Data from PubMed and Scopus were analyzed from January 2013 to August 2020. Based on inclusion/exclusion criteria, high-quality articles have been selected to become the subject of this review.RESULTS: A total of 737 papers were found but, after titles/abstracts screening for inclusion criteria and a full-text careful selection, 33 papers were deeply studied. After the exclusion of 19 papers, 15 articles remained. Eight papers dealt with animals (mice/rats), two both with animals and humans (for method validation previously built), while 5 exclusively with humans. Myocardium (6/15) and brain (6/15) were the most studied tissues. respectively in mice/rats and humans. PMI considered was up to 7.5 days in mouse studies and less than 3 days in human models.CONCLUSIONS: Because of their significant stability in both early and long PMI, miRNAs are the cleverest reference markers to be used. Temperature and environmental conditions influence mostly mRNA, while miRNAs are less susceptible to them. The best miRNA to choose depends on its tissue specificity, i.e., miR-9 and miR-125 in brain or miR-1 and miR-133 in skeletal muscle/heart

    Comparative electrochemical behavior of Prussian blue analogues as a host electrode for rare earth element recovery

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    In this paper, electrodeposited films belonging to the Prussian Blue Analogues (PBAs) family, namely, nickel-hexacyanoferrate (NiHCF) and copper-hexacyanoferrate (CuHCF), were employed as a host material for rare earth elements (REE), and the reported insertion/release study reveals a recovery capability for such valuable metals. The ion insertion/release was accomplished by adopting an electrochemically-driven process. A reversible intercalation was observed while considering both heavy and ligth rare earth elements. The amount of REEs inserted/released over the process and its kinetic evolution during the process were also studied by a chemometric approach. For CuHCF, it was seen that the intercalation of heavy rare earth elements occurs easily respect to the light ones, suggesting a possible selectivity among these ions

    Valproic acid determination by liquid chromatography coupled to mass spectrometry (LC–MS/MS) in whole blood for forensic purposes

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    Valproic acid (VPA) is a well-known drug prescribed as anti-epileptic. It has a narrow therapeutic range and shows great individual differences in pharmacodynamics and pharmacokinetics. Consequently, the therapeutical drug monitoring (TDM) in patient's plasma is of crucial importance. Liquid chromatography coupled to mass spectrometry (LC–MS/MS) has gained importance in TDM applications for its features of sensitivity, selectivity and rapidity. However, in case of VPA, the LC–MS/MS selectivity could be hampered by the lack of a sufficient number of multiple reaction monitoring (MRM) transitions describing the molecule. In fact, the product ion scan of deprotonated molecules of VPA does not produce any ion and thus most LC–MS/MS methods are based on the detection of the unique MRM transition m/z 143➔143. In this way, the advantages of selectivity in LC–MS cannot be effectively exploited. In the present method, stable analyte adducts were exploited for the determination of VPA in blood. An Acquity HSS C18 column and mobile phases consisting of 5-mM ammonium formate and acetonitrile both added 0.1% formic acid were used. Source worked in negative acquisition mode and parameters were optimized to increase the adduct (m/z 189) and dimer (m/z 287) stability, and their fragmentation were used to increase the selectivity of MRM detection. The method has been validated according to the toxicological forensic guidelines and successfully applied to 10 real blood samples. Finally, the present method showed suitable for the rapid LC–MS/MS detection of VPA in whole blood, demonstrating the possibility to increase specificity by exploiting stable in-source adducts. This should be considered of utmost importance in the case of forensic applications

    Comparison of diagenetic and low-grade metamorphic evolution of chlorite in associated metapelites and metabasites: an integrated TEM and XRD study

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73635/1/j.1525-1314.2000.00272.x.pd

    Introducing database communication technologies for TED replication in multi-domain networks

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    In multi-domain transport networks, exchange of Traffic Engineering information is required to enable effective end-to-end service provisioning and restoration by efficiently utilizing network resources. So far, several solutions have been proposed by the communication community such as the Hierarchical Path Computation Element (H-PCE) architecture. Using the H-PCE architecture a parent PCE is responsible for inter-domain path computation, while a dedicated child PCE performs intra-domain path computation within each domain. However, this approach can introduce scalability concerns especially under dynamic traffic condition such as during restoration because all path computation procedures are coordinated by the parent PCE and may require the exchange of many control messages. This paper proposes a standard communication among database systems located at the child PCEs, to exchange and share YANG-based Traffic Engineering information in multi-domain networks. By exploiting currently available database technologies, scalable and predictable performance is demonstrated for both replication mechanisms among child PCEs and information retrieval from the stored databases. Thus, this proposal enables the sharing of intra-domain information at each cPCE that can be locally used, upon failure, to speed-up the recovery procedure
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