30 research outputs found

    Effective action and density functional theory

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    The effective action for the charge density and the photon field is proposed as a generalization of the density functional. A simple definition is given for the density functional, as the functional Legendre transform of the generator functional of connected Green functions for the density and the photon field, offering systematic approximation schemes. The leading order of the perturbation expansion reproduces the Hartree-Fock equation. A renormalization group motivated method is introduced to turn on the Coulomb interaction gradually and to find corrections to the Hartree-Fock and the Kohn-Sham schemes.Comment: New references and a numerical algorithm added, to appear in Phys. Rev. B. 30 pages, no figure

    Jorge A. Swieca's contributions to quantum field theory in the 60s and 70s and their relevance in present research

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    After revisiting some high points of particle physics and QFT of the two decades from 1960 to 1980, I comment on the work by Jorge Andre Swieca. I explain how it fits into the quantum field theory during these two decades and draw attention to its relevance to the ongoing particle physics research. A particular aim of this article is to direct thr readers mindfulness to the relevance of what at the time of Swieca was called "the Schwinger Higgs screening mechanism". which, together with recent ideas which generalize the concept of gauge theories, has all the ingredients to revolutionize the issue of gauge theories and the standard model.Comment: 49 pages, expansion and actualization of text, improvement of formulations and addition of many references to be published in EPJH - Historical Perspectives on Contemporary Physic

    Neutron Diffraction Study of NiTi During Compressive Deformation and After Shape-Memory Recovery

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    Neutron diffraction measurements of internal elastic strains and texture were performed during uniaxial compressive deformation of martensitic NiTi. Rietveld refinement of the diffraction spectra was performed in order to obtain lattice parameter variations and preferred orientation of martensitic variants during deformation. The elastic internal strain is proportional to the externally applied stress but strongly dependent on crystallographic orientation. Plastic deformation by matrix twinning is consistent with Type I (1-1-1) twinning, whereby (100) and (011) planes tend to align perpendicular and parallel to the load axis, respectively. The preferred orientation ratio according to the model by March and Dollase is found to be proportional to the macroscopic plastic strain for (100) and (011) planes for loading, unloading and shape-memory recovery. To the best of our knowledge, this is the first in situ bulk measurement of reversible twinning in NiTi. Finally, shape-memory recovery results in a marked change of NiTi cell parameters

    Molecular adaptation to high pressure in cytochrome P450 1A and aryl hydrocarbon receptor systems of the deep-sea fish Coryphaenoides armatus.

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    Limited knowledge of the molecular evolution of deep-sea fish proteomes so far suggests that a few widespread residue substitutions in cytosolic proteins binding hydrophilic ligands contribute to resistance to the effects of high hydrostatic pressure (HP). Structure-function studies with additional protein systems, including membrane bound proteins, are essential to provide a more general picture of adaptation in these extremophiles. We explored molecular features of HP adaptation in proteins binding hydrophobic ligands, either in lipid bilayers (cytochrome P450 1A - CYP1A) or in the cytosol (the aryl hydrocarbon receptor - AHR), and their partners P450 oxidoreductase (POR) and AHR nuclear translocator (ARNT), respectively. Cloning studies identified the full-length coding sequence of AHR, CYP1A and POR, and a partial sequence of ARNT from Coryphaenoides armatus, an abyssal gadiform fish thriving down to 5000m depth. Inferred protein sequences were aligned with many non-deep-sea homologs to identify unique amino acid substitutions of possible relevance in HP adaptation. Positionally unique substitutions of various physicochemical properties were found in all four proteins, usually at sites of strong-to-absolute residue conservation. Some were in domains deemed important for protein-protein interaction or ligand binding. In addition, some involved removal or addition of beta-branched residues; local modifications of beta-branched residue patterns could be important to HP adaptation. In silico predictions further suggested that some unique substitutions might substantially modulate the flexibility of the polypeptide segment in which they are found. Repetitive motifs unique to the abyssal fish AHR were predicted to be rich in glycosylation sites, suggesting that post-translational changes could be involved in adaptation as well. Recombinant CYP1A and AHR showed functional properties (spectral characteristics, catalytic activity and ligand binding) that demonstrate proper folding at 1atm, indicating that they could be used as deep-sea fish protein models to further evaluate protein function under pressure

    Molecular adaptation to high pressure in cytochrome P450 1A and aryl hydrocarbon receptor systems of the deep-sea fish <i>Coryphaenoides armatus</i>

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    Limited knowledge of the molecular evolution of deep-sea fish proteomes so far suggests that a few widespread residue substitutions in cytosolic proteins binding hydrophilic ligands contribute to resistance to the effects of high hydrostatic pressure (HP). Structure-function studies with additional protein systems, including membrane bound proteins, are essential to provide a more general picture of adaptation in these extremophiles. We explored molecular features of HP adaptation in proteins binding hydrophobic ligands, either in lipid bilayers (cytochrome P450 1A - CYP1A) or in the cytosol (the aryl hydrocarbon receptor - AHR), and their partners P450 oxidoreductase (POR) and AHR nuclear translocator (ARNT), respectively. Cloning studies identified the full-length coding sequence of AHR, CYP1A and POR, and a partial sequence of ARNT from Coryphaenoides armatus, an abyssal gadiform fish thriving down to 5000 m depth. Inferred protein sequences were aligned with many non-deep-sea homologs to identify unique amino acid substitutions of possible relevance in HP adaptation. Positionally unique substitutions of various physicochemical properties were found in all four proteins, usually at sites of strong-to-absolute residue conservation. Some were in domains deemed important for protein-protein interaction or ligand binding. In addition, some involved removal or addition of beta-branched residues; local modifications of beta-branched residue patterns could be important to HP adaptation. In silico predictions further suggested that some unique substitutions might substantially modulate the flexibility of the polypeptide segment in which they are found. Repetitive motifs unique to the abyssal fish AHR were predicted to be rich in glycosylation sites, suggesting that post-translational changes could be involved in adaptation as well. Recombinant CYP1A and AHR showed functional properties (spectral characteristics, catalytic activity and ligand binding) that demonstrate proper folding at 1 atm, indicating that they could be used as deep-sea fish protein models to further evaluate protein function under pressure. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone"

    Structure of the capsid amino-terminal domain from the betaretrovirus, jaagsiekte sheep retrovirus

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    Jaagsiekte sheep retrovirus is a betaretrovirus and the causative agent of pulmonary adenocarcinoma, a transmissible lung tumour of sheep. Here we report the crystal structure of the capsid amino-terminal domain and examine the self-association properties of Jaagsiekte sheep retrovirus capsid. We find that the structure is remarkably similar to the amino-terminal domain of the alpharetrovirus, avian leukosis virus, revealing a previously undetected evolutionary similarity. Examination of capsid self-association suggests a mode of assembly not driven by the strong capsid carboxy-terminal domain interactions that characterise capsid assembly in the lentiviruses. Based on these data, we propose this structure provides a model for the capsid of betaretroviruses including the HML-2 family of endogenous human betaretroviruses

    Human Papillomavirus Vaccination and Infection in Young Sexual Minority Men: The P18 Cohort Study

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    We examined the prevalence of infection with human papillomavirus (HPV) and HIV in a cohort of young gay, bisexual, and other men who have sex with men [sexual minority men (SMM)]. HPV vaccination uptake was assessed; HIV antibody testing was performed and genetic testing for oral and anal HPV infection was undertaken. We examined both HPV vaccination and infection in relation to key demographic and structural variables. Participants (n = 486) were on average 23 years old; 70% identified as a member of a racial/ethnic minority group, and 7% identified as transgender females. Only 18.1% of the participants indicated having received the full dosage of HPV vaccination and 45.1% were unvaccinated. Slightly over half the participants (58.6%) were infected with HPV, with 58.1% testing positive for anal infection and 8.8% for oral infection. HIV seropositivity was associated with infection to oral HPV [adjusted odds ratio (AOR) = 4.03] and vaccine-preventable HPV, whereas both neighborhood-level poverty (AOR = 1.68) and HIV infection (AOR = 31.13) were associated with anal infection to HPV (AOR = 1.68). Prevalence of HPV infection is high among unvaccinated young SMM, despite the availability and eligibility for vaccination. HPV infection adds further health burden to these populations and is particularly concerning for those who are HIV positive as HIV infection increases the risk of developing HPV-related cancers. These findings underscore a missed prevention opportunity for an at-risk and underserved population and suggest the need for active strategies to increase HPV vaccination uptake in young SMM before the onset of sexual behavior. © Copyright 2019, Mary Ann Liebert, Inc., publishers 2019

    Dose-escalated donor lymphocyte infusions following reduced intensity transplantation: toxicity, chimerism, and disease responses

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    Data on the application of donor lymphocyte infusions (DLIs) following reduced-intensity transplantation (RIT) remain limited. Persistence of host antigen-presenting cells might increase the efficacy or toxicity of cellular immunotherapies. We report the results of dose-escalating DLIs in 46 patients undergoing RIT, who received a total of 109 infusions to treat mixed chimerism or residual or progressive disease. Diagnoses were myeloma (n = 19), Hodgkin lymphoma (n = 13), non-Hodgkin lymphoma (n = 10), and other (n = 4). Thirty-two had an HLA-matched family donor and 14 an unrelated donor. Grades II to IV graft-versus-host disease (GVHD) occurred in 5 sibling and 7 unrelated donor recipients. GVHD was more common (P = .002), occurred at lower T-cell doses, and was more severe in the unrelated donor cohort. Conversion from mixed to multilineage full donor chimerism occurred in 30 of 35 evaluable patients. Presence of mixed chimerism in the granulocyte lineage at the time of DLI did not predict for chimerism response or GVHD. Disease responses occurred in 63% of patients with myeloma and 70% of those with Hodgkin lymphoma and were not predicted by changes in chimerism. These data support the presence of clinically relevant graft-versus-Hodgkin activity and indicate that DLI may be associated with a significantly increased toxicity in unrelated compared to sibling donor transplant recipients receiving identical treatment protocols
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