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1.
Phys Rev Lett ; 108(16): 165006, 2012 Apr 20.
Article in English | MEDLINE | ID: mdl-22680729

ABSTRACT

In simulations of a 10 PW laser striking a solid, we demonstrate the possibility of producing a pure electron-positron plasma by the same processes as those thought to operate in high-energy astrophysical environments. A maximum positron density of 10(26) m(-3) can be achieved, 7 orders of magnitude greater than achieved in previous experiments. Additionally, 35% of the laser energy is converted to a burst of γ rays of intensity 10(22) W cm(-2), potentially the most intense γ-ray source available in the laboratory. This absorption results in a strong feedback between both pair and γ-ray production and classical plasma physics in the new "QED-plasma" regime.

2.
Phys Rev Lett ; 109(24): 245006, 2012 Dec 14.
Article in English | MEDLINE | ID: mdl-23368336

ABSTRACT

A novel absorption mechanism for linearly polarized lasers propagating in relativistically underdense solids in the ultrarelativistic (a ~ 100) regime is presented. The mechanism is based on strong synchrotron emission from electrons reinjected into the laser by the space charge field they generate at the front of the laser pulse. This laser absorption, termed reinjected electron synchrotron emission, is due to a coupling of conventional plasma physics processes to quantum electrodynamic processes in low density solids at intensities above 10(22) W/cm(2). Reinjected electron synchrotron emission is identified in 2D QED-particle-in-cell simulations and then explained in terms of 1D QED-particle-in-cell simulations and simple analytical theory. It is found that between 1% (at 10(22) W/cm(2)) and 14% (at 8 × 10(23) W/cm(2)) of the laser energy is converted into gamma ray photons, potentially providing an ultraintense future gamma ray source.

4.
Am J Respir Cell Mol Biol ; 23(2): 154-61, 2000 Aug.
Article in English | MEDLINE | ID: mdl-10919980

ABSTRACT

Although neutrophil migration from the systemic circulation involves the beta2- (or CD18) integrin family, the existence of an alternative, CD18-independent route of neutrophil extravasation to tissues has been demonstrated in animal models. The molecular interactions involved in this alternative migratory route have not yet been characterized. The objective of this study was to assess the CD18-dependency of neutrophil migration across human endothelial cells from an organ known to support CD18-independent migration, the lung, with a view to establishing an in vitro model to facilitate study of CD18-independent migration. Neutrophil migration across human pulmonary artery endothelial cells (HPAECs) in response to three different chemoattractants, formylmethionyl leucylphenyl-alanine (FMLP), interleukin (IL)-8, and leukotriene (LT) B(4), was examined. Results demonstrated that a function-blocking antibody to CD18 decreased FMLP-stimulated migration by 71.7 +/- 4.4% (P < 0.001). In contrast, migration in response to LTB(4) was decreased by only 20.5 +/- 10.2% (P < 0.01), and no significant decrease was observed with migration to IL-8. Neutrophils that migrated to FMLP had 1.7-fold more surface CD11b/CD18 compared with nonmigrated neutrophils (P < 0.01), whereas this integrin complex was not significantly upregulated on neutrophils that had migrated to IL-8 or LTB(4). Further investigation of this migratory route indicated that it did not involve the beta1 integrins (CD29) or the endothelial selectins, E- or P-selectin, nor did it require the activity of either metalloproteinases or neutrophil elastase. These results indicate that neutrophil migration across HPAECs in vitro to IL-8 and LTB(4) is predominantly CD18-independent and provides a much-needed in vitro system for examination of the neutrophil-endothelial interactions involved in this alternative migratory route.


Subject(s)
CD18 Antigens/physiology , Cell Movement/drug effects , Endothelium, Vascular/drug effects , Hydroxamic Acids , Interleukin-8/pharmacology , Leukotriene B4/pharmacology , Neutrophils/drug effects , Pyrazines , CD11 Antigens/drug effects , CD11 Antigens/metabolism , Cell Line , Chemotactic Factors/pharmacology , Dose-Response Relationship, Drug , Endothelium, Vascular/cytology , Glycine/analogs & derivatives , Glycine/pharmacology , Humans , Interleukin-8/pharmacokinetics , L-Selectin/drug effects , L-Selectin/metabolism , Leukotriene B4/pharmacokinetics , Lung/blood supply , N-Formylmethionine Leucyl-Phenylalanine/pharmacokinetics , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , Neutrophils/cytology , Neutrophils/metabolism , Permeability , Phenylalanine/analogs & derivatives , Phenylalanine/pharmacology , Protease Inhibitors/pharmacology , Sulfonamides/pharmacology , Thiophenes/pharmacology
5.
Tissue Antigens ; 55(5): 401-11, 2000 May.
Article in English | MEDLINE | ID: mdl-10885560

ABSTRACT

The consistent dysregulation of HLA expression in cervical neoplasia is likely to influence the natural history of the disease and prospects for cell-mediated vaccine therapies. We have studied the underlying mechanisms in eight new cervical cancer cell lines derived from primary tumour biopsies. At least five independent mechanisms leading to changes in HLA expression were seen: HLA class I allelic transcription but no protein; abnormal HLA class I allelic transcription; no HLA-B locus transcription; loss of heterozygosity (LOH); no gammaIFN-mediated upregulation of HLA class I expression, and/or no interferon-gamma (gammaIFN)-mediated HLA class II induction. These were evident in different combinations in 7/8 cell lines showing that multiple, mostly irreversible mechanisms not overridden by gammaIFN, are responsible for HLA dysregulation in cervical neoplasia. Point mutations were responsible for lack of HLA-A2 expression in two cases. In cell line 808, the mutation encodes a stop codon in exon 3; in cell line 778, mutation of the first intron acceptor site leads to use of an alternative AG site in exon 2, resulting in a frameshift and a stop codon after the translation of only 38 amino acids. Tumour cells showing specific HLA class I loss may have selective advantage in the face of tumour-specific cytotoxic T cells (CTL). Such immune escape mechanisms present a major obstacle for the success of CTL-mediated therapies in cervical cancer.


Subject(s)
Carcinoma, Squamous Cell/immunology , Histocompatibility Antigens Class I/immunology , Oncogene Proteins, Viral/immunology , Uterine Cervical Neoplasms/immunology , ATP Binding Cassette Transporter, Subfamily B, Member 2 , ATP-Binding Cassette Transporters/genetics , ATP-Binding Cassette Transporters/immunology , Alleles , Biopsy , Carcinoma, Squamous Cell/pathology , Carcinoma, Squamous Cell/virology , DNA Primers , Female , Gene Expression Regulation, Neoplastic/immunology , Gene Expression Regulation, Viral/immunology , Genotype , Histocompatibility Antigens Class I/genetics , Histocompatibility Testing , Humans , Oncogene Proteins, Viral/genetics , Papillomaviridae/genetics , Papillomaviridae/immunology , Papillomavirus Infections/genetics , Papillomavirus Infections/immunology , Phenotype , Receptors, Interferon/immunology , Reverse Transcriptase Polymerase Chain Reaction , Sequence Analysis, DNA , T-Lymphocytes, Cytotoxic/immunology , Transcription, Genetic/immunology , Tumor Cells, Cultured , Tumor Virus Infections/genetics , Tumor Virus Infections/immunology , Uterine Cervical Neoplasms/pathology , Uterine Cervical Neoplasms/virology , Interferon gamma Receptor
6.
Percept Mot Skills ; 42(3): 789-90, 1976 Jun.
Article in English | MEDLINE | ID: mdl-1272728

ABSTRACT

15 females with glasses tended to defend against relatively low self-perceptions of attractiveness by de-emphasizing the influence of their eyes on facial beauty.


Subject(s)
Beauty , Contact Lenses , Esthetics , Eyeglasses , Face , Self Concept , Female , Humans
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