WorldWideScience

Sample records for single unrepaired dsb

  1. DNA DSB measurements and modelling approaches based on gamma-H2AX foci time evolution

    Science.gov (United States)

    Esposito, Giuseppe; Campa, Alessandro; Antonelli, Francesca; Mariotti, Luca; Belli, Mauro; Giardullo, Paola; Simone, Giustina; Antonella Tabocchini, Maria; Ottolenghi, Andrea

    DNA double strand breaks (DSBs) induced by ionising radiation are considered the main dam-age related to the deleterious consequences in the cells. Unrepaired or mis-repaired DSBs can cause mutations or loss of chromosome regions which can eventually lead to cell death or neo-plastic transformation. Quantification of the number and complexity of DSBs induced by low doses of radiation remains a complex problem. About ten years ago Rogakou et al. proposed an immunofluorescent technique able to detect even a single DSB per cell. This approach is based on the serine 139 phosphorylation of many molecules (up to 2000) of histone H2AX (γg-H2AX) following the induction of a DSB in the DNA. DSB can be visualized as foci by immunofluores-cence by using phospho-specific antibodies, so that enumeration of foci can be used to measure DSB induction and processing. It is still not completely clear how γ-H2AX dephosphorylation takes place; however it has been related with DSB repair, in particular with the efficiency of DSB repair. In this work we analyse the H2AX phosphorylation-dephosphorylation kinetics after irradiation of primary human fibroblasts (AG1522 cell line) with radiation of differing quality, that is γ-rays and α-particles (125 keV/µm), with the aim of comparing the time evolution of γ-H2AX foci. Our results show that, after a dose of 0.5 Gy, both γ-rays and α-particles induce the maximum number of γ-H2AX foci within 30 minutes from irradiation, that this number depends on the radiation type and is consistent with the number of track traversal in α-irradiated nuclei, that the dephosphorylation kinetics are very different, being the α-induced foci rate of disappearence slower than that of γ-induced foci. In this work a modellistic approach to estimate the number of DSB induced by γ-rays detectable by using the γ-H2AX assay is presented. The competing processes of appearance and disappearance of visible foci will be modeled taking into account the

  2. Why is DsbA such an oxidizing disulfide catalyst?

    DEFF Research Database (Denmark)

    Grauschopf, U; Winther, Jakob R.; Korber, P

    1995-01-01

    in determining the exceptional oxidizing power of DsbA. Mutations that change these two residues can alter the equilibrium oxidation potential of DsbA by more than 1000-fold. A quantitative explanation for the very high redox potential of DsbA was found by measuring the pKa of a single residue, Cys-30. The pKa...

  3. Structural and Biochemical Characterization of the Oxidoreductase NmDsbA3 from Neisseria meningitidis

    Energy Technology Data Exchange (ETDEWEB)

    Vivian, Julian P.; Scoullar, Jessica; Robertson, Amy L.; Bottomley, Stephen P.; Horne, James; Chin, Yanni; Wielens, Jerome; Thompson, Philip E.; Velkov, Tony; Piek, Susannah; Byres, Emma; Beddoe, Travis; Wilce, Matthew C.J.; Kahler, Charlene M.; Rossjohn, Jamie; Scanlon, Martin J. (UWA); (Monash)

    2009-09-02

    DsbA is an enzyme found in the periplasm of Gram-negative bacteria that catalyzes the formation of disulfide bonds in a diverse array of protein substrates, many of which are involved in bacterial pathogenesis. Although most bacteria possess only a single essential DsbA, Neisseria meningitidis is unusual in that it possesses three DsbAs, although the reason for this additional redundancy is unclear. Two of these N. meningitidis enzymes (NmDsbA1 and NmDsbA2) play an important role in meningococcal attachment to human epithelial cells, whereas NmDsbA3 is considered to have a narrow substrate repertoire. To begin to address the role of DsbAs in the pathogenesis of N. meningitidis, we have determined the structure of NmDsbA3 to 2.3-{angstrom} resolution. Although the sequence identity between NmDsbA3 and other DsbAs is low, the NmDsbA3 structure adopted a DsbA-like fold. Consistent with this finding, we demonstrated that NmDsbA3 acts as a thiol-disulfide oxidoreductase in vitro and is reoxidized by Escherichia coli DsbB (EcDsbB). However, pronounced differences in the structures between DsbA3 and EcDsbA, which are clustered around the active site of the enzyme, suggested a structural basis for the unusual substrate specificity that is observed for NmDsbA3.

  4. Un-repairable DNA damage in cell due to irradiation

    International Nuclear Information System (INIS)

    Yoshii, Giichi

    1992-01-01

    Radiation-induced cell reproductive deactivation is caused by damage to DNA. In a cell, cellular DNA radical reacts with diffusion controlled rate and generates DNA peroxide radical. The chemical repair of DNA radical with hydrogen donation by thiol competes with the reaction of oxygen with same radicals in the DNA molecules. From the point reaction rates, the prolongation of radical life time is not as great as expected from the reduction in the glutathione content of the cell. This indicates that further reducting compounds (protein bound thiol) are present in the cell. The residual radicals are altered to strand breaks, base damages and so on. The effective lesions for a number of endpoints is un-repaired double strand break, which has been discovered in a cluster. This event gives risk to high LET radiation or to a track end of X-rays. For X- or electron irradiations the strand breaks are frequently induced by the interactions between sublesions on two strands in DNA. A single strand break followed by radical action may be unstable excited state, because of remaining sugar radical action and of having negative charged phosphates, in which strands breaks will be rejoined in a short time to stable state. On the same time, a break in the double helix will be immediately produced if two breaks are on either or approximately opposite locations. The formation of a double strand break in the helix depends on the ion strength of the cell. The potassium ions are largely released from polyanionic strand during irradiation, which results in the induction of denatured region. Double strand break with the denatured region seems to be un-repairable DNA damage. (author)

  5. Protein disulfide bond generation in Escherichia coli DsbB–DsbA

    International Nuclear Information System (INIS)

    Inaba, Kenji

    2008-01-01

    The crystal structure of the DsbB–DsbA–ubiquinone ternary complex has revealed a mechanism of protein disulfide bond generation in Escherichia coli. Protein disulfide bond formation is catalyzed by a series of Dsb enzymes present in the periplasm of Escherichia coli. The crystal structure of the DsbB–DsbA–ubiquinone ternary complex provided important insights into mechanisms of the de novo disulfide bond generation cooperated by DsbB and ubiquinone and of the disulfide bond shuttle from DsbB to DsbA. The structural basis for prevention of the crosstalk between the DsbA–DsbB oxidative and the DsbC–DsbD reductive pathways has also been proposed

  6. Processing of radiation-induced clustered DNA damage generates DSB in mammalian cells

    International Nuclear Information System (INIS)

    Gulston, M.K.; De Lara, C.M.; Davis, E.L.; Jenner, T.J.; O'Neill, P.

    2003-01-01

    Full text: Clustered DNA damage sites, in which two or more lesions are formed within a few helical turns of the DNA after passage of a single radiation track, are signatures of DNA modifications induced by ionizing radiation in mammalian cell. With 60 Co-radiation, the abundance of clustered DNA damage induced in CHO cells is ∼4x that of prompt double strand breaks (DSB) determined by PFGE. Less is known about the processing of non-DSB clustered DNA damage induced in cells. To optimize observation of any additional DSB formed during processing of DNA damage at 37 deg C, xrs-5 cells deficient in non-homologous end joining were used. Surprisingly, ∼30% of the DSB induced by irradiation at 37 deg C are rejoined within 4 minutes in both mutant and wild type cells. No significant mis-repair of these apparent DSB was observed. It is suggested that a class of non-DSB clustered DNA damage is formed which repair correctly within 4 min but, if 'trapped' prior to repair, are converted into DSB during the lysis procedure of PFGE. However at longer times, a proportion of non-DSB clustered DNA damage sites induced by γ-radiation are converted into DSB within ∼30 min following post-irradiation incubation at 37 deg C. The corresponding formation of additional DSB was not apparent in wild type CHO cells. From these observations, it is estimated that only ∼10% of the total yield of non DSB clustered DNA damage sites are converted into DSB through cellular processing. The biological consequences that the majority of non-DSB clustered DNA damage sites are not converted into DSBs may be significant even at low doses, since a finite chance exists of these clusters being formed in a cell by a single radiation track

  7. Chromatin dynamics during DSB repair

    Czech Academy of Sciences Publication Activity Database

    Falk, Martin; Lukášová, Emilie; Gabrielová, Barbora; Ondřej, Vladan; Kozubek, Stanislav

    2007-01-01

    Roč. 1773, č. 10 (2007), s. 1534-1545 ISSN 0167-4889 R&D Projects: GA ČR(CZ) GP204/06/P349; GA ČR(CZ) 1QS500040508; GA AV ČR(CZ) IAA1065203; GA MŠk(CZ) 1P05OC084 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : chromatin structure * double- strand breaks (DSB) * DNA repair Subject RIV: BO - Biophysics Impact factor: 4.374, year: 2007

  8. A single-strand specific lesion drives MMS-induced hyper-mutability at a double-strand break in yeast.

    Science.gov (United States)

    Yang, Yong; Gordenin, Dmitry A; Resnick, Michael A

    2010-08-05

    Localized hyper-mutability (LHM) can be important in evolution, immunity, and genetic diseases. We previously reported that single-strand DNA (ssDNA) can be an important source of damage-induced LHM in yeast. Here, we establish that the generation of LHM by methyl methanesulfonate (MMS) during repair of a chromosomal double-strand break (DSB) can result in over 0.2 mutations/kb, which is approximately 20,000-fold higher than the MMS-induced mutation density without a DSB. The MMS-induced mutations associated with DSB repair were primarily due to substitutions via translesion DNA synthesis at damaged cytosines, even though there are nearly 10 times more MMS-induced lesions at other bases. Based on this mutation bias, the promutagenic lesion dominating LHM is likely 3-methylcytosine, which is single-strand specific. Thus, the dramatic increase in mutagenesis at a DSB is concluded to result primarily from the generation of non-repairable lesions in ssDNA associated with DSB repair along with efficient induction of highly mutagenic ssDNA-specific lesions. These findings with MMS-induced LHM have broad biological implications for unrepaired damage generated in ssDNA and possibly ssRNA. Published by Elsevier B.V.

  9. Homeostatic regulation of meiotic DSB formation by ATM/ATR

    International Nuclear Information System (INIS)

    Cooper, Tim J.; Wardell, Kayleigh; Garcia, Valerie; Neale, Matthew J.

    2014-01-01

    Ataxia–telangiectasia mutated (ATM) and RAD3-related (ATR) are widely known as being central players in the mitotic DNA damage response (DDR), mounting responses to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) respectively. The DDR signalling cascade couples cell cycle control to damage-sensing and repair processes in order to prevent untimely cell cycle progression while damage still persists [1]. Both ATM/ATR are, however, also emerging as essential factors in the process of meiosis; a specialised cell cycle programme responsible for the formation of haploid gametes via two sequential nuclear divisions. Central to achieving accurate meiotic chromosome segregation is the introduction of numerous DSBs spread across the genome by the evolutionarily conserved enzyme, Spo11. This review seeks to explore and address how cells utilise ATM/ATR pathways to regulate Spo11-DSB formation, establish DSB homeostasis and ensure meiosis is completed unperturbed

  10. Homeostatic regulation of meiotic DSB formation by ATM/ATR

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Tim J.; Wardell, Kayleigh; Garcia, Valerie; Neale, Matthew J., E-mail: m.neale@sussex.ac.uk

    2014-11-15

    Ataxia–telangiectasia mutated (ATM) and RAD3-related (ATR) are widely known as being central players in the mitotic DNA damage response (DDR), mounting responses to DNA double-strand breaks (DSBs) and single-stranded DNA (ssDNA) respectively. The DDR signalling cascade couples cell cycle control to damage-sensing and repair processes in order to prevent untimely cell cycle progression while damage still persists [1]. Both ATM/ATR are, however, also emerging as essential factors in the process of meiosis; a specialised cell cycle programme responsible for the formation of haploid gametes via two sequential nuclear divisions. Central to achieving accurate meiotic chromosome segregation is the introduction of numerous DSBs spread across the genome by the evolutionarily conserved enzyme, Spo11. This review seeks to explore and address how cells utilise ATM/ATR pathways to regulate Spo11-DSB formation, establish DSB homeostasis and ensure meiosis is completed unperturbed.

  11. Mary Wollstonecraft Shelley's Frankenstein, or the modern Prometheus: a psychological study of unrepaired shame.

    Science.gov (United States)

    Severino, Sally K; Morrison, Nancy K

    2013-01-01

    Mary Wollstonecraft Shelley's modern Prometheus shows us the eternal punishment of unrepaired shame--eternal entrapment within the shame triangle of victim, perpetrator and rescuer. This paper describes how Shelley's insight--that lack of love creates a monster living in shame--is being confirmed by neuroscience and how this is exemplified in two characters--the creature and Victor Frankenstein. Additionally, it delineates how pastoral counselors can help those suffering from unrepaired shame

  12. Obstetric Outcomes in Women with Unrepaired Tetralogy of Fallot: A Case Report

    Directory of Open Access Journals (Sweden)

    Burak Karadağ

    2011-08-01

    Full Text Available Tetralogy of Fallot (TOF is the most common form of cyanotic congenital heart diseases and without corrective surgery, natural survival rate into the fourth decade was only about 3%. In pregnant patients with unrepaired TOF, pregnancy-related physiological changes is more difficult to tolerate compared to healthy pregnant woman. Discussed below a case of term pregnancy in a 20- year old woman with unrepaired TOF, was diagnosed at delivery.

  13. Comparative sequence, structure and redox analyses of Klebsiella pneumoniae DsbA show that anti-virulence target DsbA enzymes fall into distinct classes.

    Directory of Open Access Journals (Sweden)

    Fabian Kurth

    Full Text Available Bacterial DsbA enzymes catalyze oxidative folding of virulence factors, and have been identified as targets for antivirulence drugs. However, DsbA enzymes characterized to date exhibit a wide spectrum of redox properties and divergent structural features compared to the prototypical DsbA enzyme of Escherichia coli DsbA (EcDsbA. Nonetheless, sequence analysis shows that DsbAs are more highly conserved than their known substrate virulence factors, highlighting the potential to inhibit virulence across a range of organisms by targeting DsbA. For example, Salmonella enterica typhimurium (SeDsbA, 86 % sequence identity to EcDsbA shares almost identical structural, surface and redox properties. Using comparative sequence and structure analysis we predicted that five other bacterial DsbAs would share these properties. To confirm this, we characterized Klebsiella pneumoniae DsbA (KpDsbA, 81 % identity to EcDsbA. As expected, the redox properties, structure and surface features (from crystal and NMR data of KpDsbA were almost identical to those of EcDsbA and SeDsbA. Moreover, KpDsbA and EcDsbA bind peptides derived from their respective DsbBs with almost equal affinity, supporting the notion that compounds designed to inhibit EcDsbA will also inhibit KpDsbA. Taken together, our data show that DsbAs fall into different classes; that DsbAs within a class may be predicted by sequence analysis of binding loops; that DsbAs within a class are able to complement one another in vivo and that compounds designed to inhibit EcDsbA are likely to inhibit DsbAs within the same class.

  14. The C. elegans DSB-2 protein reveals a regulatory network that controls competence for meiotic DSB formation and promotes crossover assurance.

    Directory of Open Access Journals (Sweden)

    Simona Rosu

    Full Text Available For most organisms, chromosome segregation during meiosis relies on deliberate induction of DNA double-strand breaks (DSBs and repair of a subset of these DSBs as inter-homolog crossovers (COs. However, timing and levels of DSB formation must be tightly controlled to avoid jeopardizing genome integrity. Here we identify the DSB-2 protein, which is required for efficient DSB formation during C. elegans meiosis but is dispensable for later steps of meiotic recombination. DSB-2 localizes to chromatin during the time of DSB formation, and its disappearance coincides with a decline in RAD-51 foci marking early recombination intermediates and precedes appearance of COSA-1 foci marking CO-designated sites. These and other data suggest that DSB-2 and its paralog DSB-1 promote competence for DSB formation. Further, immunofluorescence analyses of wild-type gonads and various meiotic mutants reveal that association of DSB-2 with chromatin is coordinated with multiple distinct aspects of the meiotic program, including the phosphorylation state of nuclear envelope protein SUN-1 and dependence on RAD-50 to load the RAD-51 recombinase at DSB sites. Moreover, association of DSB-2 with chromatin is prolonged in mutants impaired for either DSB formation or formation of downstream CO intermediates. These and other data suggest that association of DSB-2 with chromatin is an indicator of competence for DSB formation, and that cells respond to a deficit of CO-competent recombination intermediates by prolonging the DSB-competent state. In the context of this model, we propose that formation of sufficient CO-competent intermediates engages a negative feedback response that leads to cessation of DSB formation as part of a major coordinated transition in meiotic prophase progression. The proposed negative feedback regulation of DSB formation simultaneously (1 ensures that sufficient DSBs are made to guarantee CO formation and (2 prevents excessive DSB levels that could

  15. The financial impact of unrepaired cleft lip and palate in the Philippines.

    Science.gov (United States)

    Muntz, Harlan R; Meier, Jeremy D

    2013-12-01

    There are over 96 million people in the Philippines. Close to 77 thousand persons in this country have orofacial clefting. We estimate nearly 64 thousand are unrepaired. Unemployment and underemployment because of the communication disorders associated with unrepaired clefts will affect family income and hence tax revenues. The purpose of this study is to understand the financial impact of unrepaired cleft lip and/or palate on families and identify how that would translate to the Philippine government in tax revenues. The incidence of orofacial cleft in the Philippines was estimated to be at least 1 in 750 people, with only 16% anticipated to be repaired under current conditions. Assuming a 21% unemployment rate in subjects with untreated clefts, and a tax rate of 6-12.4%, projected lost personal income and federal tax revenue was calculated. In 2012 alone the financial impact on the families may be as much as $US 73-88 million in lost revenue from unemployment and underemployment. This would cost the government between $8.0 and $9.8 million dollars in lost tax revenue. Over a 20 year period at least $US 1.7 billion dollars in family income would be affected costing the government at least $US 194 million in taxes. By appropriately caring for the cleft population tax revenues should increase substantially. The development of the infrastructure for surgical care of this problem would be costly but could be more than offset by revenues. Inattention to surgically correctable causes of communication disorders is not affordable. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  16. Characterizing ground motions that collapse steel special moment-resisting frames or make them unrepairable

    Science.gov (United States)

    Olsen, Anna H.; Heaton, Thomas H.; Hall, John F.

    2015-01-01

    This work applies 64,765 simulated seismic ground motions to four models each of 6- or 20-story, steel special moment-resisting frame buildings. We consider two vector intensity measures and categorize the building response as “collapsed,” “unrepairable,” or “repairable.” We then propose regression models to predict the building responses from the intensity measures. The best models for “collapse” or “unrepairable” use peak ground displacement and velocity as intensity measures, and the best models predicting peak interstory drift ratio, given that the frame model is “repairable,” use spectral acceleration and epsilon (ϵ) as intensity measures. The more flexible frame is always more likely than the stiffer frame to “collapse” or be “unrepairable.” A frame with fracture-prone welds is substantially more susceptible to “collapse” or “unrepairable” damage than the equivalent frame with sound welds. The 20-story frames with fracture-prone welds are more vulnerable to P-delta instability and have a much higher probability of collapse than do any of the 6-story frames.

  17. Expression and crystallization of SeDsbA, SeDsbL and SeSrgA from Salmonella enterica serovar Typhimurium

    International Nuclear Information System (INIS)

    Jarrott, R.; Shouldice, S. R.; Gunčar, G.; Totsika, M.; Schembri, M. A.; Heras, B.

    2010-01-01

    The cloning, purification, crystallization and preliminary crystallographic studies of three DsbA-like proteins present in S. enterica serovar Typhimurium, SeDsbA, SeDsbL and SeSrgA, are reported. Pathogens require protein-folding enzymes to produce functional virulence determinants. These foldases include the Dsb family of proteins, which catalyze oxidative folding in bacteria. Bacterial disulfide catalytic processes have been well characterized in Escherichia coli K-12 and these mechanisms have been extrapolated to other organisms. However, recent research indicates that the K-12 complement of Dsb proteins is not common to all bacteria. Importantly, many pathogenic bacteria have an extended arsenal of Dsb catalysts that is linked to their virulence. To help to elucidate the process of oxidative folding in pathogens containing a wide repertoire of Dsb proteins, Salmonella enterica serovar Typhimurium has been focused on. This Gram-negative bacterium contains three DsbA proteins: SeDsbA, SeDsbL and SeSrgA. Here, the expression, purification, crystallization and preliminary diffraction analysis of these three proteins are reported. SeDsbA, SeDsbL and SeSrgA crystals diffracted to resolution limits of 1.55, 1.57 and 2.6 Å and belonged to space groups P2 1 , P2 1 2 1 2 and C2, respectively

  18. Folding of DsbB in mixed micelles

    DEFF Research Database (Denmark)

    Otzen, Daniel

    2003-01-01

    state and an unfolding intermediate that accumulates only under unfolding conditions at high mole fractions of SDS. The stability of DsbB is around 4.4 kcal/mol in DM, and this is halved upon reduction of the two periplasmic disulfide bonds, and is sensitive to mutagenesis. With the caveat that kinetic...... is sensitive to changes in lipid and detergent composition. As an attempt to overcome this problem, I present a kinetic analysis of the folding of a membrane protein, disulfide bond reducing protein B (DsbB), in a mixed micelle system consisting of varying molar ratios of sodium dodecyl sulfate (SDS...

  19. Excess single-stranded DNA inhibits meiotic double-strand break repair.

    Directory of Open Access Journals (Sweden)

    Rebecca Johnson

    2007-11-01

    Full Text Available During meiosis, self-inflicted DNA double-strand breaks (DSBs are created by the protein Spo11 and repaired by homologous recombination leading to gene conversions and crossovers. Crossover formation is vital for the segregation of homologous chromosomes during the first meiotic division and requires the RecA orthologue, Dmc1. We analyzed repair during meiosis of site-specific DSBs created by another nuclease, VMA1-derived endonuclease (VDE, in cells lacking Dmc1 strand-exchange protein. Turnover and resection of the VDE-DSBs was assessed in two different reporter cassettes that can repair using flanking direct repeat sequences, thereby obviating the need for a Dmc1-dependent DNA strand invasion step. Access of the single-strand binding complex replication protein A, which is normally used in all modes of DSB repair, was checked in chromatin immunoprecipitation experiments, using antibody against Rfa1. Repair of the VDE-DSBs was severely inhibited in dmc1Delta cells, a defect that was associated with a reduction in the long tract resection required to initiate single-strand annealing between the flanking repeat sequences. Mutants that either reduce Spo11-DSB formation or abolish resection at Spo11-DSBs rescued the repair block. We also found that a replication protein A component, Rfa1, does not accumulate to expected levels at unrepaired single-stranded DNA (ssDNA in dmc1Delta cells. The requirement of Dmc1 for VDE-DSB repair using flanking repeats appears to be caused by the accumulation of large quantities of ssDNA that accumulate at Spo11-DSBs when Dmc1 is absent. We propose that these resected DSBs sequester both resection machinery and ssDNA binding proteins, which in wild-type cells would normally be recycled as Spo11-DSBs repair. The implication is that repair proteins are in limited supply, and this could reflect an underlying mechanism for regulating DSB repair in wild-type cells, providing protection from potentially harmful effects

  20. Budding yeast ATM/ATR control meiotic double-strand break (DSB levels by down-regulating Rec114, an essential component of the DSB-machinery.

    Directory of Open Access Journals (Sweden)

    Jesús A Carballo

    2013-06-01

    Full Text Available An essential feature of meiosis is Spo11 catalysis of programmed DNA double strand breaks (DSBs. Evidence suggests that the number of DSBs generated per meiosis is genetically determined and that this ability to maintain a pre-determined DSB level, or "DSB homeostasis", might be a property of the meiotic program. Here, we present direct evidence that Rec114, an evolutionarily conserved essential component of the meiotic DSB-machinery, interacts with DSB hotspot DNA, and that Tel1 and Mec1, the budding yeast ATM and ATR, respectively, down-regulate Rec114 upon meiotic DSB formation through phosphorylation. Mimicking constitutive phosphorylation reduces the interaction between Rec114 and DSB hotspot DNA, resulting in a reduction and/or delay in DSB formation. Conversely, a non-phosphorylatable rec114 allele confers a genome-wide increase in both DSB levels and in the interaction between Rec114 and the DSB hotspot DNA. These observations strongly suggest that Tel1 and/or Mec1 phosphorylation of Rec114 following Spo11 catalysis down-regulates DSB formation by limiting the interaction between Rec114 and DSB hotspots. We also present evidence that Ndt80, a meiosis specific transcription factor, contributes to Rec114 degradation, consistent with its requirement for complete cessation of DSB formation. Loss of Rec114 foci from chromatin is associated with homolog synapsis but independent of Ndt80 or Tel1/Mec1 phosphorylation. Taken together, we present evidence for three independent ways of regulating Rec114 activity, which likely contribute to meiotic DSBs-homeostasis in maintaining genetically determined levels of breaks.

  1. Budding Yeast ATM/ATR Control Meiotic Double-Strand Break (DSB) Levels by Down-Regulating Rec114, an Essential Component of the DSB-machinery

    Science.gov (United States)

    Carballo, Jesús A.; Panizza, Silvia; Serrentino, Maria Elisabetta; Johnson, Anthony L.; Geymonat, Marco; Borde, Valérie; Klein, Franz; Cha, Rita S.

    2013-01-01

    An essential feature of meiosis is Spo11 catalysis of programmed DNA double strand breaks (DSBs). Evidence suggests that the number of DSBs generated per meiosis is genetically determined and that this ability to maintain a pre-determined DSB level, or “DSB homeostasis”, might be a property of the meiotic program. Here, we present direct evidence that Rec114, an evolutionarily conserved essential component of the meiotic DSB-machinery, interacts with DSB hotspot DNA, and that Tel1 and Mec1, the budding yeast ATM and ATR, respectively, down-regulate Rec114 upon meiotic DSB formation through phosphorylation. Mimicking constitutive phosphorylation reduces the interaction between Rec114 and DSB hotspot DNA, resulting in a reduction and/or delay in DSB formation. Conversely, a non-phosphorylatable rec114 allele confers a genome-wide increase in both DSB levels and in the interaction between Rec114 and the DSB hotspot DNA. These observations strongly suggest that Tel1 and/or Mec1 phosphorylation of Rec114 following Spo11 catalysis down-regulates DSB formation by limiting the interaction between Rec114 and DSB hotspots. We also present evidence that Ndt80, a meiosis specific transcription factor, contributes to Rec114 degradation, consistent with its requirement for complete cessation of DSB formation. Loss of Rec114 foci from chromatin is associated with homolog synapsis but independent of Ndt80 or Tel1/Mec1 phosphorylation. Taken together, we present evidence for three independent ways of regulating Rec114 activity, which likely contribute to meiotic DSBs-homeostasis in maintaining genetically determined levels of breaks. PMID:23825959

  2. Repair of DNA DSB in higher eukaryotes

    International Nuclear Information System (INIS)

    Wang, H.; Perrault, A.R.; Takeda, Y.; Iliakis, G.

    2003-01-01

    Cells of higher eukaryotes process within minutes double strand breaks (DSBs) in their genome using a NHEJ apparatus that engages DNA-PKcs, Ku, DNA ligase IV, XRCC4, and other as of yet unidentified factors. Although chemical inhibition, or mutation, in any of these factors delays processing, cells ultimately remove the majority of DNA DSBs using an alternative pathway operating with slower kinetics. This alternative pathway is active in mutants deficient in genes of the RAD52 epistasis group. We proposed, therefore, that it reflects an alternative form of NHEJ that operates as a backup (B-NHEJ) to the DNA-PK- dependent (D-NHEJ) pathway, rather than homology directed repair of DSBs. We studied the role of Ku and DNA-PKcs in the coordination of these pathways using as a model end joining of restriction endonuclease linearized plasmid DNA in whole cell extracts. Efficient error-free endjoining observed in such in-vitro reactions is strongly inhibited by anti-Ku antibodies. The inhibition requires DNA-PKcs, despite that fact that Ku efficiently binds DNA ends in the presence of antibodies, or in the absence of DNA-PKcs. Strong inhibition of DNA endjoining is also mediated by wortmannin, an inhibitor of DNA-PKcs, in the presence but not in the absence of Ku, and this inhibition can be rescued by pre-incubating the reaction with double stranded oligonucleotides. The results are compatible with a role of Ku in directing endjoining to a DNA-PK dependent pathway, mediated by efficient end binding and productive interactions with DNA-PKcs. On the other hand, efficient end joining is observed in extracts of cells lacking DNA-PKcs, as well as in Ku-depleted extracts sugggesting the operation of alternative pathways. Extracts depleted of Ku and DNA-PKcs rejoin blunt ends, as well as homologous ends with 3' or 5' protruding single strands with similar efficiency, but addition of Ku suppresses joining of blunt ends and homologous ends with 3' overhangs. We propose that the

  3. Outcomes following surgical repair using layered closure of unrepaired 4th degree perineal tear in rural western Uganda.

    Science.gov (United States)

    Goh, Judith T W; Tan, Stephanie B M; Natukunda, Harriet; Singasi, Isaac; Krause, Hannah G

    2016-11-01

    In many rural low-income countries, perineal tears at time of vaginal birth are not repaired at time of delivery. The aims of this study are to describe the surgical technique for management of the unrepaired 4th degree tear, performed without flaps, and short-term follow up on anal incontinence symptoms using a validated questionnaire. Women presenting to fistula camps in western Uganda with unrepaired 4th degree tears were interviewed using the Cleveland Clinic Continence Score. Interviews were undertaken pre-operatively, at 4-6 weeks post-operatively and 12 months following surgery. Repair of the 4th degree tear was performed in layers, with an overlapping anal sphincter repair and reconstruction of the perineal body, without flaps. All women were examined prior to discharge. 68 women completed pre-operative Cleveland Clinic Continence Scores. Prior to surgery, 59 % of women complained of daily incontinence to solid stools. Over 70 % of women complained of restriction to lifestyle due to the unrepaired 4th degree tear. About 50 % of the women are rejected by their husbands because of the condition. Only 1 woman had wound breakdown on Day 2. At 4 to 6 weeks follow-up, 61 women were contacted and all reported perfect continence. This study highlights the hidden problem of unrepaired 4th degree tears in rural areas of low-income countries where most deliveries are undertaken in the village without professional health care workers. These tears have significant impact on quality of life and anal incontinence. Short-term outcomes following surgical repair using a layered closure are promising.

  4. Effect of antioxidants on x-ray induced DNA SSB and DSB in different cell systems

    International Nuclear Information System (INIS)

    Ramadu, Kadem

    1998-01-01

    The effect of x-ray radiation or antioxidants such as actinomycin D, cycloheximide and mitomycin C is studied on CHO, BHK and HeLa cells. X-ray radiation caused DNA single strand breaks (SSB) and double strand breaks (DSB) are prevented by cycloheximide and actinomycin-D. The DSB and SSB are significant in the case of x-ray radiation in combination with MMC, but different with actinomycin-D and cycloheximide in combination with x-ray radiation which causes less number of SSB and DSB. The ISC is observed more with x-ray radiation in combination with antioxidants mitomycin C (MMC) than that of cycloheximide and actinomycin-D, which individually causes inhibition of ISC induced by x-ray radiation. This observation proves that the MMC has an additive effect on x-ray induced ISC during cell proliferation. During cell proliferation, cell viability is observed with x-ray radiation and antioxidants which are dependent on the cell cycle phase. However, in the control cells, the initial Go-phase has shown negligible difference in percent cell viability thereby during S-phase gradual increase in the cell viability, and cell proliferation have been found to be stopped at G2+M-phase. On the contrary, cell viability and the extent of cell proliferation with x-ray radiation in combination with MMC have shown more damage (OH-damage) than is caused by x-ray radiation and MMC, separately. But, the fact is that actinomycin-D and cycloheximide act as antioxidants preventing thereby free radical formation and cell death, caused by x-ray radiation. During cell proliferation, cells observed from S and (G2+M) phase exhibit difference in cell viability in all the treatments alone and in combination. HeLa cells have been found insensitive to x-ray radiation and could be ascribed to the presence of glutathione transferase, which is less in CHO/BHK cell line. (author)

  5. Preliminary crystallographic data of the three homologues of the thiol–disulfide oxidoreductase DsbA in Neisseria meningitidis

    Energy Technology Data Exchange (ETDEWEB)

    Lafaye, Céline [Laboratoire des Protéines Membranaires, Institut de Biologie Structurale, CEA/CNRS/Université Joseph Fourier, 41 Rue Jules Horowitz, 38027 Grenoble CEDEX 01 (France); Iwena, Thomas; Ferrer, Jean-Luc [Laboratoire de Cristallogénèse et Cristallisation des Protéines, Institut de Biologie Structurale, CEA/CNRS/Université Joseph Fourier, 41 Rue Jules Horowitz, 38027 Grenoble CEDEX 01 (France); Kroll, J. Simon [Department of Paediatrics, Imperial College London, St Mary’s Hospital Campus, Norfolk Place, London W2 1PG (United Kingdom); Griat, Mickael; Serre, Laurence, E-mail: laurence.serre@ibs.fr [Laboratoire des Protéines Membranaires, Institut de Biologie Structurale, CEA/CNRS/Université Joseph Fourier, 41 Rue Jules Horowitz, 38027 Grenoble CEDEX 01 (France)

    2008-02-01

    The Neisseria meningitidis genome possesses three genes encoding active DsbAs. To throw light on the reason for this genetic multiplicity, the three enzymes have been purified and crystallized. Bacterial virulence depends on the correct folding of surface-exposed proteins, a process that is catalyzed by the thiol-disulfide oxidoreductase DsbA, which facilitates the synthesis of disulfide bonds in Gram-negative bacteria. Uniquely among bacteria, the Neisseria meningitidis genome possesses three genes encoding active DsbAs: DsbA1, DsbA2 and DsbA3. DsbA1 and DsbA2 have been characterized as lipoproteins involved in natural competence and in host-interactive biology, while the function of DsbA3 remains unknown. In an attempt to shed light on the reason for this multiplicity of dsbA genes, the three enzymes from N. meningitidis have been purified and crystallized in the presence of high concentrations of ammonium sulfate. The best crystals were obtained using DsbA1 and DsbA3; they belong to the orthorhombic and tetragonal systems and diffract to 1.5 and 2.7 Å resolution, respectively.

  6. Virtual Screening of Peptide and Peptidomimetic Fragments Targeted to Inhibit Bacterial Dithiol Oxidase DsbA.

    Directory of Open Access Journals (Sweden)

    Wilko Duprez

    Full Text Available Antibacterial drugs with novel scaffolds and new mechanisms of action are desperately needed to address the growing problem of antibiotic resistance. The periplasmic oxidative folding system in Gram-negative bacteria represents a possible target for anti-virulence antibacterials. By targeting virulence rather than viability, development of resistance and side effects (through killing host native microbiota might be minimized. Here, we undertook the design of peptidomimetic inhibitors targeting the interaction between the two key enzymes of oxidative folding, DsbA and DsbB, with the ultimate goal of preventing virulence factor assembly. Structures of DsbB--or peptides--complexed with DsbA revealed key interactions with the DsbA active site cysteine, and with a hydrophobic groove adjacent to the active site. The present work aimed to discover peptidomimetics that target the hydrophobic groove to generate non-covalent DsbA inhibitors. The previously reported structure of a Proteus mirabilis DsbA active site cysteine mutant, in a non-covalent complex with the heptapeptide PWATCDS, was used as an in silico template for virtual screening of a peptidomimetic fragment library. The highest scoring fragment compound and nine derivatives were synthesized and evaluated for DsbA binding and inhibition. These experiments discovered peptidomimetic fragments with inhibitory activity at millimolar concentrations. Although only weakly potent relative to larger covalent peptide inhibitors that interact through the active site cysteine, these fragments offer new opportunities as templates to build non-covalent inhibitors. The results suggest that non-covalent peptidomimetics may need to interact with sites beyond the hydrophobic groove in order to produce potent DsbA inhibitors.

  7. Influence of chromatin condensation on the number of direct DSB damages induced by ions studied using a Monte Carlo code

    International Nuclear Information System (INIS)

    Dos Santos, M.; Clairand, I.; Gruel, G.; Barquinero, J.F.; Villagrasa, C.; Incerti, S.

    2014-01-01

    The purpose of this work is to evaluate the influence of the chromatin condensation on the number of direct double-strand break (DSB) damages induced by ions. Two geometries of chromosome territories containing either condensed or de-condensed chromatin were implemented as biological targets in the Geant4 Monte Carlo simulation code and proton and alpha irradiation was simulated using the Geant4-DNA processes. A DBSCAN algorithm was used in order to detect energy deposition clusters that could give rise to single-strand breaks or DSBs on the DNA molecule. The results of this study show an increase in the number and complexity of DNA DSBs in condensed chromatin when compared with de-condensed chromatin. This work aims to evaluate the influence of the chromatin condensation in the number and complexity of direct DSB damages induced by proton and alpha irradiation. With the simulations of this study, the increase in the number and complexity of DSB-like clusters induced by ions in the heterochromatin when compared with euchromatin regions of the cell nucleus has been observed and quantified. These results suggest that condensed chromatin can be the location of more severe radiation-induced lesions, more difficult to repair, than de-condensed chromatin. On the other hand, it was also observed that, whatever the chromatin condensation, more possible damages are found after proton irradiation compared with alpha particles of the same LET. Nevertheless, as already remarked, this study concerns only the direct effect of ionising radiation that can be calculated from the results of the physical stage simulated with Geant4-DNA. To include indirect effects induced by radicals around the DNA molecule, the elements needed for simulating the chemical stage are being developed in the frame of the Geant4-DNA project(15, 16) and they are planned to be included in future work. With a complete calculation (direct + indirect damages) it would then be possible to estimate an energy

  8. Crystallization and preliminary diffraction analysis of a DsbA homologue from Wolbachia pipientis

    Energy Technology Data Exchange (ETDEWEB)

    Kurz, M. [Institute for Molecular Bioscience and ARC Special Research Centre for Functional and Applied Genomics, University of Queensland, St Lucia, QLD 4072 (Australia); Iturbe-Ormaetxe, I. [School of Integrative Biology, The University of Queensland, St Lucia, QLD 4072 (Australia); Jarrott, R. [Institute for Molecular Bioscience and ARC Special Research Centre for Functional and Applied Genomics, University of Queensland, St Lucia, QLD 4072 (Australia); O’Neill, S. L. [School of Integrative Biology, The University of Queensland, St Lucia, QLD 4072 (Australia); Byriel, K. A.; Martin, J. L., E-mail: j.martin@imb.uq.edu.au; Heras, B., E-mail: j.martin@imb.uq.edu.au [Institute for Molecular Bioscience and ARC Special Research Centre for Functional and Applied Genomics, University of Queensland, St Lucia, QLD 4072 (Australia)

    2008-02-01

    The first crystallization of a W. pipientis protein, α-DsbA1, was achieved using hanging-drop and sitting-drop vapour diffusion. α-DsbA1 is one of two DsbA homologues encoded by the Gram-negative α-proteobacterium Wolbachia pipientis, an endosymbiont that can behave as a reproductive parasite in insects and as a mutualist in medically important filarial nematodes. The α-DsbA1 protein is thought to be important for the folding and secretion of Wolbachia proteins involved in the induction of reproductive distortions. Crystals of native and SeMet α-DsbA1 were grown by vapour diffusion and belong to the monoclinic space group C2, with unit-cell parameters a = 71.4, b = 49.5, c = 69.3 Å, β = 107.0° and one molecule in the asymmetric unit (44% solvent content). X-ray data were recorded from native crystals to a resolution of 2.01 Å using a copper anode and data from SeMet α-DsbA1 crystals were recorded to 2.45 Å resolution using a chromium anode.

  9. Local changes of higher-order chromatin structure during DSB-repair

    International Nuclear Information System (INIS)

    Falk, M; Lukasova, E; Gabrielova, B; Ondrej, V; Kozubek, S

    2008-01-01

    We show that double-strand breaks (DSBs) induced in DNA of human cells by γ-radiation arise mainly in active, gene-rich, decondensed chromatin. We demonstrate that DSBs show limited movement in living cells, occasionally resulting in their permanent clustering, which poses a risk of incorrect DNA rejoining. In addition, some DSBs remain unrepaired for several days after irradiation, forming lesions repairable only with difficulty which are hazardous for genome stability. These 'late' DSBs colocalize with heterochromatin markers (dimethylated histone H3 at lysine 9, HP1 and CENP-A proteins), despite the low density of the surrounding chromatin. This indicates that there is epigenetic silencing of loci close to unrepaired DSBs and/or stabilization of damaged decondensed chromatin loops during repair and post-repair reconstitution of chromatin structure

  10. Repaired tetralogy of Fallot with coexisting unrepaired partial anomalous pulmonary venous connection is associated with diminished right ventricular ejection fraction and more severe right ventricular dilation

    International Nuclear Information System (INIS)

    Chan, Sherwin S.; Whitehead, Kevin K.; Kim, Timothy S.; Fu, Gregory L.; Fogel, Mark A.; Harris, Matthew A.; Keller, Marc S.

    2015-01-01

    There is an established association between tetralogy of Fallot and partial anomalous pulmonary venous connections. This association is important because surgically repaired tetralogy patients have increased risk of right heart failure. We hypothesize that partial anomalous venous connections increase right ventricular volumes and worsen right ventricular failure. We reviewed cardiac MRI exams performed at a tertiary pediatric hospital from January 2005 to January 2014. We identified patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection. We used age- and gender-matched repaired tetralogy patients without partial anomalous pulmonary venous connection as controls. We analyzed the MRI results and surgical course and performed comparative statistics to identify group differences. There were eight patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection and 16 controls. In all cases, the partial anomalous pulmonary venous connection was not detected on preoperative echocardiography. There were no significant differences in surgical course and body surface area between the two groups. Repaired tetralogy patients with unrepaired partial anomalous pulmonary venous connection showed significantly higher indexed right ventricular end diastolic volume (149 ± 33 mL/m 2 vs. 118 ± 30 mL/m 2 ), right ventricle to left ventricle size ratios (3.1 ± 1.3 vs. 1.9 ± 0.5) and a higher incidence of reduced right ventricular ejection fraction compared to controls (3/8 vs. 0/16). Repaired tetralogy of Fallot with unrepaired partial anomalous pulmonary venous connection is associated with reduced right ventricular ejection fraction and more significant right ventricular dilation. (orig.)

  11. Repaired tetralogy of Fallot with coexisting unrepaired partial anomalous pulmonary venous connection is associated with diminished right ventricular ejection fraction and more severe right ventricular dilation

    Energy Technology Data Exchange (ETDEWEB)

    Chan, Sherwin S. [Children' s Mercy Hospital and Clinics, Department of Radiology, Kansas City, MO (United States); Whitehead, Kevin K.; Kim, Timothy S.; Fu, Gregory L.; Fogel, Mark A.; Harris, Matthew A. [Children' s Hospital of Philadelphia, Department of Cardiology, Philadelphia, PA (United States); Keller, Marc S. [Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States)

    2015-09-15

    There is an established association between tetralogy of Fallot and partial anomalous pulmonary venous connections. This association is important because surgically repaired tetralogy patients have increased risk of right heart failure. We hypothesize that partial anomalous venous connections increase right ventricular volumes and worsen right ventricular failure. We reviewed cardiac MRI exams performed at a tertiary pediatric hospital from January 2005 to January 2014. We identified patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection. We used age- and gender-matched repaired tetralogy patients without partial anomalous pulmonary venous connection as controls. We analyzed the MRI results and surgical course and performed comparative statistics to identify group differences. There were eight patients with repaired tetralogy and unrepaired partial anomalous pulmonary venous connection and 16 controls. In all cases, the partial anomalous pulmonary venous connection was not detected on preoperative echocardiography. There were no significant differences in surgical course and body surface area between the two groups. Repaired tetralogy patients with unrepaired partial anomalous pulmonary venous connection showed significantly higher indexed right ventricular end diastolic volume (149 ± 33 mL/m{sup 2} vs. 118 ± 30 mL/m{sup 2}), right ventricle to left ventricle size ratios (3.1 ± 1.3 vs. 1.9 ± 0.5) and a higher incidence of reduced right ventricular ejection fraction compared to controls (3/8 vs. 0/16). Repaired tetralogy of Fallot with unrepaired partial anomalous pulmonary venous connection is associated with reduced right ventricular ejection fraction and more significant right ventricular dilation. (orig.)

  12. Suppression of DNA-dependent protein kinase sensitize cells to radiation without affecting DSB repair

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Ann-Sofie, E-mail: ann-sofie.gustafsson@bms.uu.se; Abramenkovs, Andris; Stenerlöw, Bo

    2014-11-15

    Highlights: • We reduced the level of DNA-PKcs with siRNA and examined cells after γ-irradiation. • Low DNA-PKcs levels lead to radiosensitivity but did not affect repair of DSB. • Low DNA-PKcs levels may block progression of mitosis. • DNA-PKcs role in mitotic progression is independent of its role in DSB repair. • We suggest different mechanisms by which loss of DNA-PKcs function sensitize cells. - Abstract: Efficient and correct repair of DNA double-strand break (DSB) is critical for cell survival. Defects in the DNA repair may lead to cell death, genomic instability and development of cancer. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is an essential component of the non-homologous end joining (NHEJ) which is the major DSB repair pathway in mammalian cells. In the present study, by using siRNA against DNA-PKcs in four human cell lines, we examined how low levels of DNA-PKcs affected cellular response to ionizing radiation. Decrease of DNA-PKcs levels by 80–95%, induced by siRNA treatment, lead to extreme radiosensitivity, similar to that seen in cells completely lacking DNA-PKcs and low levels of DNA-PKcs promoted cell accumulation in G2/M phase after irradiation and blocked progression of mitosis. Surprisingly, low levels of DNA-PKcs did not affect the repair capacity and the removal of 53BP1 or γ-H2AX foci and rejoining of DSB appeared normal. This was in strong contrast to cells completely lacking DNA-PKcs and cells treated with the DNA-PKcs inhibitor NU7441, in which DSB repair were severely compromised. This suggests that there are different mechanisms by which loss of DNA-PKcs functions can sensitize cells to ionizing radiation. Further, foci of phosphorylated DNA-PKcs (T2609 and S2056) co-localized with DSB and this was independent of the amount of DNA-PKcs but foci of DNA-PKcs was only seen in siRNA-treated cells. Our study emphasizes on the critical role of DNA-PKcs for maintaining survival after radiation exposure

  13. Suppression of DNA-dependent protein kinase sensitize cells to radiation without affecting DSB repair

    International Nuclear Information System (INIS)

    Gustafsson, Ann-Sofie; Abramenkovs, Andris; Stenerlöw, Bo

    2014-01-01

    Highlights: • We reduced the level of DNA-PKcs with siRNA and examined cells after γ-irradiation. • Low DNA-PKcs levels lead to radiosensitivity but did not affect repair of DSB. • Low DNA-PKcs levels may block progression of mitosis. • DNA-PKcs role in mitotic progression is independent of its role in DSB repair. • We suggest different mechanisms by which loss of DNA-PKcs function sensitize cells. - Abstract: Efficient and correct repair of DNA double-strand break (DSB) is critical for cell survival. Defects in the DNA repair may lead to cell death, genomic instability and development of cancer. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is an essential component of the non-homologous end joining (NHEJ) which is the major DSB repair pathway in mammalian cells. In the present study, by using siRNA against DNA-PKcs in four human cell lines, we examined how low levels of DNA-PKcs affected cellular response to ionizing radiation. Decrease of DNA-PKcs levels by 80–95%, induced by siRNA treatment, lead to extreme radiosensitivity, similar to that seen in cells completely lacking DNA-PKcs and low levels of DNA-PKcs promoted cell accumulation in G2/M phase after irradiation and blocked progression of mitosis. Surprisingly, low levels of DNA-PKcs did not affect the repair capacity and the removal of 53BP1 or γ-H2AX foci and rejoining of DSB appeared normal. This was in strong contrast to cells completely lacking DNA-PKcs and cells treated with the DNA-PKcs inhibitor NU7441, in which DSB repair were severely compromised. This suggests that there are different mechanisms by which loss of DNA-PKcs functions can sensitize cells to ionizing radiation. Further, foci of phosphorylated DNA-PKcs (T2609 and S2056) co-localized with DSB and this was independent of the amount of DNA-PKcs but foci of DNA-PKcs was only seen in siRNA-treated cells. Our study emphasizes on the critical role of DNA-PKcs for maintaining survival after radiation exposure

  14. Rv2969c, essential for optimal growth in Mycobacterium tuberculosis, is a DsbA-like enzyme that interacts with VKOR-derived peptides and has atypical features of DsbA-like disulfide oxidases

    International Nuclear Information System (INIS)

    Premkumar, Lakshmanane; Heras, Begoña; Duprez, Wilko; Walden, Patricia; Halili, Maria; Kurth, Fabian; Fairlie, David P.; Martin, Jennifer L.

    2013-01-01

    The gene product of M. tuberculosis Rv2969c is shown to be a disulfide oxidase enzyme that has a canonical DsbA-like fold with novel structural and functional characteristics. The bacterial disulfide machinery is an attractive molecular target for developing new antibacterials because it is required for the production of multiple virulence factors. The archetypal disulfide oxidase proteins in Escherichia coli (Ec) are DsbA and DsbB, which together form a functional unit: DsbA introduces disulfides into folding proteins and DsbB reoxidizes DsbA to maintain it in the active form. In Mycobacterium tuberculosis (Mtb), no DsbB homologue is encoded but a functionally similar but structurally divergent protein, MtbVKOR, has been identified. Here, the Mtb protein Rv2969c is investigated and it is shown that it is the DsbA-like partner protein of MtbVKOR. It is found that it has the characteristic redox features of a DsbA-like protein: a highly acidic catalytic cysteine, a highly oxidizing potential and a destabilizing active-site disulfide bond. Rv2969c also has peptide-oxidizing activity and recognizes peptide segments derived from the periplasmic loops of MtbVKOR. Unlike the archetypal EcDsbA enzyme, Rv2969c has little or no activity in disulfide-reducing and disulfide-isomerase assays. The crystal structure of Rv2969c reveals a canonical DsbA fold comprising a thioredoxin domain with an embedded helical domain. However, Rv2969c diverges considerably from other DsbAs, including having an additional C-terminal helix (H8) that may restrain the mobility of the catalytic helix H1. The enzyme is also characterized by a very shallow hydrophobic binding surface and a negative electrostatic surface potential surrounding the catalytic cysteine. The structure of Rv2969c was also used to model the structure of a paralogous DsbA-like domain of the Ser/Thr protein kinase PknE. Together, these results show that Rv2969c is a DsbA-like protein with unique properties and a limited

  15. Rv2969c, essential for optimal growth in Mycobacterium tuberculosis, is a DsbA-like enzyme that interacts with VKOR-derived peptides and has atypical features of DsbA-like disulfide oxidases

    Energy Technology Data Exchange (ETDEWEB)

    Premkumar, Lakshmanane, E-mail: p.lakshmanane@imb.uq.edu.au; Heras, Begoña; Duprez, Wilko; Walden, Patricia; Halili, Maria; Kurth, Fabian; Fairlie, David P.; Martin, Jennifer L., E-mail: p.lakshmanane@imb.uq.edu.au [University of Queensland, St Lucia, QLD 4067 (Australia)

    2013-10-01

    The gene product of M. tuberculosis Rv2969c is shown to be a disulfide oxidase enzyme that has a canonical DsbA-like fold with novel structural and functional characteristics. The bacterial disulfide machinery is an attractive molecular target for developing new antibacterials because it is required for the production of multiple virulence factors. The archetypal disulfide oxidase proteins in Escherichia coli (Ec) are DsbA and DsbB, which together form a functional unit: DsbA introduces disulfides into folding proteins and DsbB reoxidizes DsbA to maintain it in the active form. In Mycobacterium tuberculosis (Mtb), no DsbB homologue is encoded but a functionally similar but structurally divergent protein, MtbVKOR, has been identified. Here, the Mtb protein Rv2969c is investigated and it is shown that it is the DsbA-like partner protein of MtbVKOR. It is found that it has the characteristic redox features of a DsbA-like protein: a highly acidic catalytic cysteine, a highly oxidizing potential and a destabilizing active-site disulfide bond. Rv2969c also has peptide-oxidizing activity and recognizes peptide segments derived from the periplasmic loops of MtbVKOR. Unlike the archetypal EcDsbA enzyme, Rv2969c has little or no activity in disulfide-reducing and disulfide-isomerase assays. The crystal structure of Rv2969c reveals a canonical DsbA fold comprising a thioredoxin domain with an embedded helical domain. However, Rv2969c diverges considerably from other DsbAs, including having an additional C-terminal helix (H8) that may restrain the mobility of the catalytic helix H1. The enzyme is also characterized by a very shallow hydrophobic binding surface and a negative electrostatic surface potential surrounding the catalytic cysteine. The structure of Rv2969c was also used to model the structure of a paralogous DsbA-like domain of the Ser/Thr protein kinase PknE. Together, these results show that Rv2969c is a DsbA-like protein with unique properties and a limited

  16. High throughput measurement of γH2AX DSB repair kinetics in a healthy human population.

    Directory of Open Access Journals (Sweden)

    Preety M Sharma

    Full Text Available The Columbia University RABiT (Rapid Automated Biodosimetry Tool quantifies DNA damage using fingerstick volumes of blood. One RABiT protocol quantifies the total γ-H2AX fluorescence per nucleus, a measure of DNA double strand breaks (DSB by an immunofluorescent assay at a single time point. Using the recently extended RABiT system, that assays the γ-H2AX repair kinetics at multiple time points, the present small scale study followed its kinetics post irradiation at 0.5 h, 2 h, 4 h, 7 h and 24 h in lymphocytes from 94 healthy adults. The lymphocytes were irradiated ex vivo with 4 Gy γ rays using an external Cs-137 source. The effect of age, gender, race, ethnicity, alcohol use on the endogenous and post irradiation total γ-H2AX protein yields at various time points were statistically analyzed. The endogenous γ-H2AX levels were influenced by age, race and alcohol use within Hispanics. In response to radiation, induction of γ-H2AX yields at 0.5 h and peak formation at 2 h were independent of age, gender, ethnicity except for race and alcohol use that delayed the peak to 4 h time point. Despite the shift in the peak observed, the γ-H2AX yields reached close to baseline at 24 h for all groups. Age and race affected the rate of progression of the DSB repair soon after the yields reached maximum. Finally we show a positive correlation between endogenous γ-H2AX levels with radiation induced γ-H2AX yields (RIY (r=0.257, P=0.02 and a negative correlation with residuals (r=-0.521, P=<0.0001. A positive correlation was also observed between RIY and DNA repair rate (r=0.634, P<0.0001. Our findings suggest age, race, ethnicity and alcohol use influence DSB γ-H2AX repair kinetics as measured by RABiT immunofluorescent assay.

  17. Structural and Biochemical Characterization of Xylella fastidiosa DsbA Family Members: New insightsinto the Enzyme-Substrate Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldi, F.; Meza, A; Gulmarges, B

    2009-01-01

    Disulfide oxidoreductase DsbA catalyzes disulfide bond formation in proteins secreted to the periplasm and has been related to the folding process of virulence factors in many organisms. It is among the most oxidizing of the thioredoxin-like proteins, and DsbA redox power is understood in terms of the electrostatic interactions involving the active site motif CPHC. The plant pathogen Xylella fastidiosa has two chromosomal genes encoding two oxidoreductases belonging to the DsbA family, and in one of them, the canonical motif CPHC is replaced by CPAC. Biochemical assays showed that both X. fastidiosa homologues have similar redox properties and the determination of the crystal structure of XfDsbA revealed substitutions in the active site of X. fastidiosa enzymes, which are proposed to compensate for the lack of the conserved histidine in XfDsbA2. In addition, electron density maps showed a ligand bound to the XfDsbA active site, allowing the characterization of the enzyme interaction with an 8-mer peptide. Finally, surface analysis of XfDsbA and XfDsbA2 suggests that X. fastidiosa enzymes may have different substrate specificities.

  18. Constructing Periodic Timetables using MIP - a case study from DSB S-train

    DEFF Research Database (Denmark)

    Nielsen, Morten N.; Hove, Bjørn; Clausen, Jens

    2006-01-01

    We describe a mathematical model to create operational timetable alternatives in DSB S-tog a/s. The model is a mixed integer program implemented in GAMS and solved by CPLEX. We investigate the impact of automatic merges of lines and perform scenario analysis for a subset of the parameters...

  19. Correlation of Meiotic DSB Formation and Transcription Initiation Around Fission Yeast Recombination Hotspots.

    Science.gov (United States)

    Yamada, Shintaro; Okamura, Mika; Oda, Arisa; Murakami, Hiroshi; Ohta, Kunihiro; Yamada, Takatomi

    2017-06-01

    Meiotic homologous recombination, a critical event for ensuring faithful chromosome segregation and creating genetic diversity, is initiated by programmed DNA double-strand breaks (DSBs) formed at recombination hotspots. Meiotic DSB formation is likely to be influenced by other DNA-templated processes including transcription, but how DSB formation and transcription interact with each other has not been understood well. In this study, we used fission yeast to investigate a possible interplay of these two events. A group of hotspots in fission yeast are associated with sequences similar to the cyclic AMP response element and activated by the ATF/CREB family transcription factor dimer Atf1-Pcr1. We first focused on one of those hotspots, ade6-3049 , and Atf1. Our results showed that multiple transcripts, shorter than the ade6 full-length messenger RNA, emanate from a region surrounding the ade6-3049 hotspot. Interestingly, we found that the previously known recombination-activation region of Atf1 is also a transactivation domain, whose deletion affected DSB formation and short transcript production at ade6-3049 These results point to a possibility that the two events may be related to each other at ade6-3049 In fact, comparison of published maps of meiotic transcripts and hotspots suggested that hotspots are very often located close to meiotically transcribed regions. These observations therefore propose that meiotic DSB formation in fission yeast may be connected to transcription of surrounding regions. Copyright © 2017 by the Genetics Society of America.

  20. Analytical model of chemical phase and formation of DSB in chromosomes by ionizing radiation

    Czech Academy of Sciences Publication Activity Database

    Barilla, J.; Lokajíček, Miloš; Pisaková, Hana; Šimr, P.

    2013-01-01

    Roč. 36, č. 1 (2013), s. 11-17 ISSN 0158-9938 Institutional support: RVO:68378271 Keywords : radiobiological mechanism * chemical phase * DSB formation * oxygen effect Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 0.848, year: 2013

  1. Targeting Bacterial Dsb Proteins for the Development of Anti-Virulence Agents

    Directory of Open Access Journals (Sweden)

    Roxanne P. Smith

    2016-07-01

    Full Text Available Recent years have witnessed a dramatic increase in bacterial antimicrobial resistance and a decline in the development of novel antibiotics. New therapeutic strategies are urgently needed to combat the growing threat posed by multidrug resistant bacterial infections. The Dsb disulfide bond forming pathways are potential targets for the development of antimicrobial agents because they play a central role in bacterial pathogenesis. In particular, the DsbA/DsbB system catalyses disulfide bond formation in a wide array of virulence factors, which are essential for many pathogens to establish infections and cause disease. These redox enzymes are well placed as antimicrobial targets because they are taxonomically widespread, share low sequence identity with human proteins, and many years of basic research have provided a deep molecular understanding of these systems in bacteria. In this review, we discuss disulfide bond catalytic pathways in bacteria and their significance in pathogenesis. We also review the use of different approaches to develop inhibitors against Dsb proteins as potential anti-virulence agents, including fragment-based drug discovery, high-throughput screening and other structure-based drug discovery methods.

  2. Rolling Stock Planning at DSB S-tog - Processes, Cost Structures and Requirements

    DEFF Research Database (Denmark)

    Thorlacius, Per

    A central issue for operators of suburban passenger train transport systems is providing sufficient number of seats for the passengers while at the same time minimising operating costs. The process of providing this is called rolling stock planning. This technical report documents the terminology......, the processes, the cost structures and the requirements for rolling stock planning at DSB S-tog, the suburban passenger train operator of the City of Copenhagen. The focus of the technical report is directed at practical train operator oriented issues. The technical report is thought to serve as a basis...... for investigating better methods to perform the rolling stock planning (to be the topic of later papers). This technical report is produced as a part of the current industrial Ph. D. project to improve the rolling stock planning process of DSB S-tog....

  3. Screening of Pesticides with the Potential of Inducing DSB and Successive Recombinational Repair

    Directory of Open Access Journals (Sweden)

    Karen Suárez-Larios

    2017-01-01

    Full Text Available A study was realized to ascertain whether eight selected pesticides would induce double strand breaks (DSB in lymphocyte cultures and whether this damage would induce greater levels of proteins Rad51 participating in homologous recombination or of p-Ku80 participating in nonhomologous end joining. Only five pesticides were found to induce DSB of which only glyphosate and paraoxon induced a significant increase of p-Ku80 protein, indicating that nonhomologous end joining recombinational DNA repair system would be activated. The type of gamma-H2AX foci observed was comparable to that induced by etoposide at similar concentrations. These results are of importance since these effects occurred at low concentrations in the micromolar range, in acute treatments to the cells. Effects over longer exposures in actual environmental settings are expected to produce cumulative damage if repeated events of recombination take place over time.

  4. Understanding the role of RecN in DSB repair pathway in Deinococcus radiodurans

    International Nuclear Information System (INIS)

    Pellegrino, S.

    2012-01-01

    Deinococcus radiodurans is a Gram-positive bacterium known for its extreme resistance to a broad variety of DNA damaging agents. Among these, Ionizing Radiations and desiccation are the most harmful for the cell, since they introduce breaks in the genome. Double Strand Breaks (DSB) are particularly hazardous for the cell and they need to be repaired very efficiently, in order to avoid mutations leading to altered, if not lethal, phenotypes. Homologous Recombination (HR) is the most efficient mechanism by which DSBs are repaired. D. radiodurans is able to completely restore its genome in only 3 hours, and it accomplishes the entire process through the RecFOR pathway. In order to be repaired, DSBs first need to be recognized. The protein believed to be responsible for this important step that takes place soon after the damage occurs in the cell, is RecN. RecN is recruited at the early stages of DNA repair and in vivo studies have demonstrated its propensity to localize to discrete foci. In vitro studies also suggest that RecN possesses a DNA end-joining activity previously observed for SMC proteins (such as cohesin), which are structurally related to RecN. Several structural studies have been carried out on the SMC-like protein, Rad50, but so far no structural information is available for RecN. The work presented here focused on the structural characterization of RecN and its constitutive domains. We obtained crystal structures of three partially overlapping constructs of RecN and Small Angle X-ray Scattering was performed on the individual domains and the full-length protein. The study of RecN in solution complemented our crystallographic study and enabled us to build a reliable, atomic model of the full-length protein. Mutations were designed and the mutant RecN proteins were produced in order to characterize the ATP hydrolysis activity of RecN, which is a conserved feature of this family of proteins. Extensive biochemical studies were carried out on wild-type and

  5. Crystal Structure of the Dithiol Oxidase DsbA Enzyme from Proteus Mirabilis Bound Non-covalently to an Active Site Peptide Ligand

    Science.gov (United States)

    Kurth, Fabian; Duprez, Wilko; Premkumar, Lakshmanane; Schembri, Mark A.; Fairlie, David P.; Martin, Jennifer L.

    2014-01-01

    The disulfide bond forming DsbA enzymes and their DsbB interaction partners are attractive targets for development of antivirulence drugs because both are essential for virulence factor assembly in Gram-negative pathogens. Here we characterize PmDsbA from Proteus mirabilis, a bacterial pathogen increasingly associated with multidrug resistance. PmDsbA exhibits the characteristic properties of a DsbA, including an oxidizing potential, destabilizing disulfide, acidic active site cysteine, and dithiol oxidase catalytic activity. We evaluated a peptide, PWATCDS, derived from the partner protein DsbB and showed by thermal shift and isothermal titration calorimetry that it binds to PmDsbA. The crystal structures of PmDsbA, and the active site variant PmDsbAC30S were determined to high resolution. Analysis of these structures allows categorization of PmDsbA into the DsbA class exemplified by the archetypal Escherichia coli DsbA enzyme. We also present a crystal structure of PmDsbAC30S in complex with the peptide PWATCDS. The structure shows that the peptide binds non-covalently to the active site CXXC motif, the cis-Pro loop, and the hydrophobic groove adjacent to the active site of the enzyme. This high-resolution structural data provides a critical advance for future structure-based design of non-covalent peptidomimetic inhibitors. Such inhibitors would represent an entirely new antibacterial class that work by switching off the DSB virulence assembly machinery. PMID:24831013

  6. Functional and structural studies of the disulfide isomerase DsbC from the plant pathogen Xylella fastidiosa reveals a redox-dependent oligomeric modulation in vitro.

    Science.gov (United States)

    Santos, Clelton A; Toledo, Marcelo A S; Trivella, Daniela B B; Beloti, Lilian L; Schneider, Dilaine R S; Saraiva, Antonio M; Crucello, Aline; Azzoni, Adriano R; Souza, Alessandra A; Aparicio, Ricardo; Souza, Anete P

    2012-10-01

    Xylella fastidiosa is a Gram-negative bacterium that grows as a biofilm inside the xylem vessels of susceptible plants and causes several economically relevant crop diseases. In the present study, we report the functional and low-resolution structural characterization of the X. fastidiosa disulfide isomerase DsbC (XfDsbC). DsbC is part of the disulfide bond reduction/isomerization pathway in the bacterial periplasm and plays an important role in oxidative protein folding. In the present study, we demonstrate the presence of XfDsbC during different stages of X. fastidiosa biofilm development. XfDsbC was not detected during X. fastidiosa planktonic growth; however, after administering a sublethal copper shock, we observed an overexpression of XfDsbC that also occurred during planktonic growth. These results suggest that X. fastidiosa can use XfDsbC in vivo under oxidative stress conditions similar to those induced by copper. In addition, using dynamic light scattering and small-angle X-ray scattering, we observed that the oligomeric state of XfDsbC in vitro may be dependent on the redox environment. Under reducing conditions, XfDsbC is present as a dimer, whereas a putative tetrameric form was observed under nonreducing conditions. Taken together, our findings demonstrate the overexpression of XfDsbC during biofilm formation and provide the first structural model of a bacterial disulfide isomerase in solution. © 2012 The Authors Journal compilation © 2012 FEBS.

  7. Persistence of Repair Proteins at Unrepaired DNA Damage Distinguishes Diseases with ERCC2 (XPD) Mutations: Cancer-Prone Xeroderma Pigmentosum vs. Non-Cancer-Prone Trichothiodystrophy

    Science.gov (United States)

    Boyle, Jennifer; Ueda, Takahiro; Oh, Kyu-Seon; Imoto, Kyoko; Tamura, Deborah; Jagdeo, Jared; Khan, Sikandar G.; Nadem, Carine; DiGiovanna, John J.; Kraemer, Kenneth H.

    2012-01-01

    Patients with xeroderma pigmentosum (XP) have a 1,000-fold increase in ultraviolet (UV)-induced skin cancers while trichothiodystrophy (TTD) patients, despite mutations in the same genes, ERCC2 (XPD) or ERCC3 (XPB), are cancer-free. Unlike XP cells, TTD cells have a nearly normal rate of removal of UV-induced 6-4 photoproducts (6-4PP) in their DNA and low levels of the basal transcription factor, TFIIH. We examined seven XP, TTD, and XP/TTD complex patients and identified mutations in the XPD gene. We discovered large differences in nucleotide excision repair (NER) protein recruitment to sites of localized UV damage in TTD cells compared to XP or normal cells. XPC protein was rapidly localized in all cells. XPC was redistributed in TTD, and normal cells by 3 hr postirradiation, but remained localized in XP cells at 24-hr postirradiation. In XP cells recruitment of other NER proteins (XPB, XPD, XPG, XPA, and XPF) was also delayed and persisted at 24 hr (p < 0.001). In TTD cells with defects in the XPD, XPB, or GTF2H5 (TTDA) genes, in contrast, recruitment of these NER proteins was reduced compared to normals at early time points (p < 0.001) and remained low at 24 hr postirradiation. These data indicate that in XP persistence of NER proteins at sites of unrepaired DNA damage is associated with greatly increased skin cancer risk possibly by blockage of translesion DNA synthesis. In contrast, in TTD, low levels of unstable TFIIH proteins do not accumulate at sites of unrepaired photoproducts and may permit normal translesion DNA synthesis without increased skin cancer. PMID:18470933

  8. Fragment library screening identifies hits that bind to the non-catalytic surface of Pseudomonas aeruginosa DsbA1

    Science.gov (United States)

    Headey, Stephen J.; Vazirani, Mansha; Shouldice, Stephen R.; Coinçon, Mathieu; Tay, Stephanie; Morton, Craig J.; Simpson, Jamie S.; Martin, Jennifer L.

    2017-01-01

    At a time when the antibiotic drug discovery pipeline has stalled, antibiotic resistance is accelerating with catastrophic implications for our ability to treat bacterial infections. Globally we face the prospect of a future when common infections can once again kill. Anti-virulence approaches that target the capacity of the bacterium to cause disease rather than the growth or survival of the bacterium itself offer a tantalizing prospect of novel antimicrobials. They may also reduce the propensity to induce resistance by removing the strong selection pressure imparted by bactericidal or bacteriostatic agents. In the human pathogen Pseudomonas aeruginosa, disulfide bond protein A (PaDsbA1) plays a central role in the oxidative folding of virulence factors and is therefore an attractive target for the development of new anti-virulence antimicrobials. Using a fragment-based approach we have identified small molecules that bind to PaDsbA1. The fragment hits show selective binding to PaDsbA1 over the DsbA protein from Escherichia coli, suggesting that developing species-specific narrow-spectrum inhibitors of DsbA enzymes may be feasible. Structures of a co-complex of PaDsbA1 with the highest affinity fragment identified in the screen reveal that the fragment binds on the non-catalytic surface of the protein at a domain interface. This biophysical and structural data represent a starting point in the development of higher affinity compounds, which will be assessed for their potential as selective PaDsbA1 inhibitors. PMID:28346540

  9. Higher-order chromatin structure in DSB induction, repair and misrepair

    Czech Academy of Sciences Publication Activity Database

    Falk, Martin; Lukášová, Emilie; Kozubek, Stanislav

    2010-01-01

    Roč. 704, 1-3 (2010), s. 88-100 ISSN 1383-5742 R&D Projects: GA MŠk ME 919; GA AV ČR(CZ) IAA500040802; GA AV ČR(CZ) 1QS500040508 Grant - others:GA MŠk(CZ) LC535 Program:LC Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : DNA double strand breaks * DSB repair * higher-order chromatin structure Subject RIV: BO - Biophysics Impact factor: 8.741, year: 2010

  10. Análisis funcional de DsbA una tiol oxidorreductasa de Rhizobium leguminosarum

    OpenAIRE

    Vega de los Reyes, Rosa Mª

    2009-01-01

    Las proteínas que se exportan fuera del citoplasma bacteriano constituyen hasta un 20% del total de proteínas sintetizadas. Algunas de estas proteínas necesitan adquirir su conformación tridimensional particular en el citoplasma, incorporando frecuentemente cofactores metálicos antes de su transporte. Dicho transporte está mediado por el sistema Tat que es capaz de transportar proteínas que presentan un péptido señal característico en conformación plegada. Se ha postulado DsbA como proteína d...

  11. Biochemical Kinetics Model of DSB Repair and GammaH2AX FOCI by Non-homologous End Joining

    Science.gov (United States)

    Cucinotta, Francis, A.; Pluth, Janice M.; Anderson, Jennifer A.; Harper, Jane V.; O'Neill, Peter

    2007-01-01

    We developed a biochemical kinetics approach to describe the repair of double strand breaks (DSB) produced by low LET radiation by modeling molecular events associated with the mechanisms of non-homologous end-joining (NHEJ). A system of coupled non-linear ordinary differential equations describes the induction of DSB and activation pathways for major NHEJ components including Ku(sub 70/80), DNA-PK(sub cs), and the Ligase IV-XRCC4 hetero-dimer. The autophosphorylation of DNA-PK(sub cs and subsequent induction of gamma-H2AX foci observed after ionizing radiation exposure were modeled. A two-step model of DNA-PK(sub cs) regulation of repair was developed with the initial step allowing access of other NHEJ components to breaks, and a second step limiting access to Ligase IV-XRCC4. Our model assumes that the transition from the first to second-step depends on DSB complexity, with a much slower-rate for complex DSB. The model faithfully reproduced several experimental data sets, including DSB rejoining as measured by pulsed-field electrophoresis (PFGE), quantification of the induction of gamma-H2AX foci, and live cell imaging of the induction of Ku(sub 70/80). Predictions are made for the behaviors of NHEJ components at low doses and dose-rates, where a steady-state is found at dose-rates of 0.1 Gy/hr or lower.

  12. Analytical model of chemical phase and formation of DSB in chromosomes by ionizing radiation.

    Science.gov (United States)

    Barilla, Jiří; Lokajíček, Miloš; Pisaková, Hana; Simr, Pavel

    2013-03-01

    Mathematical analytical model of the processes running in individual radical clusters during the chemical phase (under the presence of radiomodifiers) proposed by us earlier has been further developed and improved. It has been applied to the data presented by Blok and Loman characterizing the oxygen effect in SSB and DSB formation (in water solution and at low-LET radiation) also in the region of very small oxygen concentrations, which cannot be studied with the help of experiments done with living cells. In this new analysis the values of all reaction rates and diffusion parameters known from literature have been made use of. The great increase of SSB and DSB at zero oxygen concentration may follow from the fact that at small oxygen concentrations the oxygen absorbs other radicals while at higher concentrations the formation of oxygen radicals prevails. It explains the double oxygen effect found already earlier by Ewing. The model may be easily extended to include also the effects of other radiomodifiers present in medium during irradiation.

  13. Analytical model of chemical phase and formation of DSB in chromosomes by ionizing radiation

    International Nuclear Information System (INIS)

    Barilla, Jiři; Simr, Pavel; Lokajíček, Miloš; Pisaková, Hana

    2013-01-01

    Mathematical analytical model of the processes running in individual radical clusters during the chemical phase (under the presence of radiomodifiers) proposed by us earlier has been further developed and improved. It has been applied to the data presented by Blok and Loman characterizing the oxygen effect in SSB and DSB formation (in water solution and at low-LET radiation) also in the region of very small oxygen concentrations, which cannot be studied with the help of experiments done with living cells. In this new analysis the values of all reaction rates and diffusion parameters known from literature have been made use of. The great increase of SSB and DSB at zero oxygen concentration may follow from the fact that at small oxygen concentrations the oxygen absorbs other radicals while at higher concentrations the formation of oxygen radicals prevails. It explains the double oxygen effect found already earlier by Ewing. The model may be easily extended to include also the effects of other radiomodifiers present in medium during irradiation.

  14. The spatial regulation of meiotic recombination hotspots: are all DSB hotspots crossover hotspots?

    Science.gov (United States)

    Serrentino, Maria-Elisabetta; Borde, Valérie

    2012-07-15

    A key step for the success of meiosis is programmed homologous recombination, during which crossovers, or exchange of chromosome arms, take place. Crossovers increase genetic diversity but their main function is to ensure accurate chromosome segregation. Defects in crossover number and position produce aneuploidies that represent the main cause of miscarriages and chromosomal abnormalities such as Down's syndrome. Recombination is initiated by the formation of programmed double strand breaks (DSBs), which occur preferentially at places called DSB hotspots. Among all DSBs generated, only a small fraction is repaired by crossover, the other being repaired by other homologous recombination pathways. Crossover maps have been generated in a number of organisms, defining crossover hotspots. With the availability of genome-wide maps of DSBs as well as the ability to measure genetically the repair outcome at several hotspots, it is becoming more and more clear that not all DSB hotspots behave the same for crossover formation, suggesting that chromosomal features distinguish different types of hotspots. Copyright © 2012. Published by Elsevier Inc.

  15. Functional and evolutionary analyses of Helicobacter pylori HP0231 (DsbK protein with strong oxidative and chaperone activity characterized by a highly diverged dimerization domain

    Directory of Open Access Journals (Sweden)

    Katarzyna Marta Bocian-Ostrzycka

    2015-10-01

    Full Text Available Helicobacter pylori does not encode the classical DsbA/DsbB oxidoreductases that are crucial for oxidative folding of extracytoplasmic proteins. Instead, this microorganism encodes an untypical two proteins playing a role in disulfide bond formation – periplasmic HP0231, which structure resembles that of EcDsbC/DsbG, and its redox partner, a membrane protein HpDsbI (HP0595 with a -propeller structure. The aim of presented work was to assess relations between HP0231 structure and function.We showed that HP0231 is most closely related evolutionarily to the catalytic domain of DsbG, even though it possesses a catalytic motif typical for canonical DsbA proteins. Similarly, the highly diverged N-terminal dimerization domain is homologous to the dimerization domain of DsbG. To better understand the functioning of this atypical oxidoreductase, we examined its activity using in vivo and in vitro experiments. We found that HP0231 exhibits oxidizing and chaperone activities but no isomerizing activity, even though H. pylori does not contain a classical DsbC. We also show that HP0231 is not involved in the introduction of disulfide bonds into HcpC (Helicobacter cysteine-rich protein C, a protein involved in the modulation of the H. pylori interaction with its host. Additionally, we also constructed a truncated version of HP0231 lacking the dimerization domain, denoted HP0231m, and showed that it acts in E. coli cells in a DsbB-dependent manner. In contrast, HP0231m and classical monomeric EcDsbA (Escherichia coli DsbA protein were both unable to complement the lack of HP0231 in H. pylori cells, though they exist in oxidized forms. HP0231m is inactive in the insulin reduction assay and possesses high chaperone activity, in contrast to EcDsbA. In conclusion, HP0231 combines oxidative functions characteristic of DsbA proteins and chaperone activity characteristic of DsbC/DsbG, and it lacks isomerization activity.

  16. New Modeling and Simulation Platform for Communications Systems:(I Double Sideband Suppressed Carrier AM Modulator DSB-SC

    Directory of Open Access Journals (Sweden)

    H. A. Ahmed

    2012-08-01

    Full Text Available The main goal of this paper is to introduce a new platform for the implementation and simulation of communication systems. SCILAB/SCICOS is an open source software for conducting communication system related experiments, aiming to provide an experimentation platform for research on communication theories. Double Sideband Suppressed Carrier (DSB-SC Modulator is modeled and simulated using this platform.

  17. The Multiple Localized Glyceraldehyde-3-Phosphate Dehydrogenase Contributes to the Attenuation of the Francisella tularensis dsbA Deletion Mutant

    Czech Academy of Sciences Publication Activity Database

    Pavkova, I.; Kopečková, M.; Klimentová, J.; Schmidt, M.; Sheshko, V.; Sobol, Margaryta; Žáková, J.; Hozák, Pavel; Stulík, J.

    2017-01-01

    Roč. 7, zima (2017), č. článku 503. ISSN 2235-2988 Institutional support: RVO:68378050 Keywords : DsbA * SILAC * glyceraldehyde-3-phosphate dehydrogenase * Francisella tularensis * moonlighting Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biochemistry and molecular biology Impact factor: 4.300, year: 2016

  18. Cytogenetic Response to Ionizing Radiation Exposure in Human Fibroblasts with Suppressed Expression of Non-DSB Repair Genes

    Science.gov (United States)

    Zhang, Ye; Rohde, Larry H.; Emami, Kamal; Hammond, Dianne; Mehta, Satish K.; Jeevarajan, Antony S.; Pierson, Duane L.; Wu, Honglu

    2009-01-01

    Changes of gene expression profile are one of the most important biological responses in living cells after ionizing radiation (IR) exposure. Although some studies have shown that genes up-regulated by IR may play important roles in DNA damage repair, the relationship between the regulation of gene expression by IR, particularly genes not known for their roles in double-strand break (DSB) repair, and its impact on cytogenetic responses has not been well studied. The purpose of this study is to identify new roles of IR inducible genes in radiation-induced chromosome aberrations and micronuclei formation. In the study, the expression of 25 genes selected on the basis of their transcriptional changes in response to IR was individually knocked down by small interfering RNA in human fibroblast cells. Frequencies of micronuclei (MN) formation and chromosome aberrations were measured to determine the efficiency of cytogenetic repair, and the fraction of bi-nucleated cells in the MN analysis was used as a marker for cell cycle progression. In response to gamma radiation, the formation of MN was significantly increased by suppressed expression of five genes: Ku70 (DSB repair pathway), XPA (nucleotide excision repair pathway), RPA1 (mismatch repair pathway), RAD17 and RBBP8 (cell cycle control). Knocked-down expression of four genes (MRE11A, RAD51 in the DSB pathway, SESN1, and SUMO1) significantly inhibited cell cycle progression, possibly because of severe impairment of DNA damage repair. Moreover, decreased XPA, p21, or MLH1 expression resulted in both significantly enhanced cell cycle progression and increased yields of chromosome aberrations, indicating that these gene products modulate both cell cycle control and DNA damage repair. Nine of these eleven genes, whose knock-down expression affected cytogenetic repair, were up-regulated in cells exposed to gamma radiation, suggesting that genes transcriptionally modulated by IR were critical to regulate IR

  19. The Multiple Localized Glyceraldehyde-3-Phosphate Dehydrogenase Contributes to the Attenuation of the Francisella tularensis dsbA Deletion Mutant

    Directory of Open Access Journals (Sweden)

    Ivona Pavkova

    2017-12-01

    Full Text Available The DsbA homolog of Francisella tularensis was previously demonstrated to be required for intracellular replication and animal death. Disruption of the dsbA gene leads to a pleiotropic phenotype that could indirectly affect a number of different cellular pathways. To reveal the broad effects of DsbA, we compared fractions enriched in membrane proteins of the wild-type FSC200 strain with the dsbA deletion strain using a SILAC-based quantitative proteomic analysis. This analysis enabled identification of 63 proteins with significantly altered amounts in the dsbA mutant strain compared to the wild-type strain. These proteins comprise a quite heterogeneous group including hypothetical proteins, proteins associated with membrane structures, and potential secreted proteins. Many of them are known to be associated with F. tularensis virulence. Several proteins were selected for further studies focused on their potential role in tularemia's pathogenesis. Of them, only the gene encoding glyceraldehyde-3-phosphate dehydrogenase, an enzyme of glycolytic pathway, was found to be important for full virulence manifestations both in vivo and in vitro. We next created a viable mutant strain with deleted gapA gene and analyzed its phenotype. The gapA mutant is characterized by reduced virulence in mice, defective replication inside macrophages, and its ability to induce a protective immune response against systemic challenge with parental wild-type strain. We also demonstrate the multiple localization sites of this protein: In addition to within the cytosol, it was found on the cell surface, outside the cells, and in the culture medium. Recombinant GapA was successfully obtained, and it was shown that it binds host extracellular serum proteins like plasminogen, fibrinogen, and fibronectin.

  20. Rapid MCNP simulation of DNA double strand break (DSB) relative biological effectiveness (RBE) for photons, neutrons, and light ions.

    Science.gov (United States)

    Stewart, Robert D; Streitmatter, Seth W; Argento, David C; Kirkby, Charles; Goorley, John T; Moffitt, Greg; Jevremovic, Tatjana; Sandison, George A

    2015-11-07

    To account for particle interactions in the extracellular (physical) environment, information from the cell-level Monte Carlo damage simulation (MCDS) for DNA double strand break (DSB) induction has been integrated into the general purpose Monte Carlo N-particle (MCNP) radiation transport code system. The effort to integrate these models is motivated by the need for a computationally efficient model to accurately predict particle relative biological effectiveness (RBE) in cell cultures and in vivo. To illustrate the approach and highlight the impact of the larger scale physical environment (e.g. establishing charged particle equilibrium), we examined the RBE for DSB induction (RBEDSB) of x-rays, (137)Cs γ-rays, neutrons and light ions relative to γ-rays from (60)Co in monolayer cell cultures at various depths in water. Under normoxic conditions, we found that (137)Cs γ-rays are about 1.7% more effective at creating DSB than γ-rays from (60)Co (RBEDSB  =  1.017) whereas 60-250 kV x-rays are 1.1 to 1.25 times more efficient at creating DSB than (60)Co. Under anoxic conditions, kV x-rays may have an RBEDSB up to 1.51 times as large as (60)Co γ-rays. Fission neutrons passing through monolayer cell cultures have an RBEDSB that ranges from 2.6 to 3.0 in normoxic cells, but may be as large as 9.93 for anoxic cells. For proton pencil beams, Monte Carlo simulations suggest an RBEDSB of about 1.2 at the tip of the Bragg peak and up to 1.6 a few mm beyond the Bragg peak. Bragg peak RBEDSB increases with decreasing oxygen concentration, which may create opportunities to apply proton dose painting to help address tumor hypoxia. Modeling of the particle RBE for DSB induction across multiple physical and biological scales has the potential to aid in the interpretation of laboratory experiments and provide useful information to advance the safety and effectiveness of hadron therapy in the treatment of cancer.

  1. Fat-Specific DsbA-L Overexpression Promotes Adiponectin Multimerization and Protects Mice From Diet-Induced Obesity and Insulin Resistance

    Science.gov (United States)

    Liu, Meilian; Xiang, Ruihua; Wilk, Sarah Ann; Zhang, Ning; Sloane, Lauren B.; Azarnoush, Kian; Zhou, Lijun; Chen, Hongzhi; Xiang, Guangda; Walter, Christi A.; Austad, Steven N.; Musi, Nicolas; DeFronzo, Ralph A.; Asmis, Reto; Scherer, Philipp E.; Dong, Lily Q.; Liu, Feng

    2012-01-01

    The antidiabetic and antiatherosclerotic effects of adiponectin make it a desirable drug target for the treatment of metabolic and cardiovascular diseases. However, the adiponectin-based drug development approach turns out to be difficult due to extremely high serum levels of this adipokine. On the other hand, a significant correlation between adiponectin multimerization and its insulin-sensitizing effects has been demonstrated, suggesting a promising alternative therapeutic strategy. Here we show that transgenic mice overexpressing disulfide bond A oxidoreductase-like protein in fat (fDsbA-L) exhibited increased levels of total and the high-molecular-weight form of adiponectin compared with wild-type (WT) littermates. The fDsbA-L mice also displayed resistance to diet-induced obesity, insulin resistance, and hepatic steatosis compared with WT control mice. The protective effects of DsbA-L overexpression on diet-induced insulin resistance, but not increased body weight and fat cell size, were significantly decreased in adiponectin-deficient fDsbA-L mice (fDsbA-L/Ad−/−). In addition, the fDsbA-L/Ad−/− mice displayed greater activity and energy expenditure compared with adiponectin knockout mice under a high-fat diet. Taken together, our results demonstrate that DsbA-L protects mice from diet-induced obesity and insulin resistance through adiponectin-dependent and independent mechanisms. In addition, upregulation of DsbA-L could be an effective therapeutic approach for the treatment of obesity and its associated metabolic disorders. PMID:22807031

  2. Sulfur Denitrosylation by an Engineered Trx-like DsbG Enzyme Identifies Nucleophilic Cysteine Hydrogen Bonds as Key Functional Determinant.

    Science.gov (United States)

    Lafaye, Céline; Van Molle, Inge; Tamu Dufe, Veronica; Wahni, Khadija; Boudier, Ariane; Leroy, Pierre; Collet, Jean-François; Messens, Joris

    2016-07-15

    Exposure of bacteria to NO results in the nitrosylation of cysteine thiols in proteins and low molecular weight thiols such as GSH. The cells possess enzymatic systems that catalyze the denitrosylation of these modified sulfurs. An important player in these systems is thioredoxin (Trx), a ubiquitous, cytoplasmic oxidoreductase that can denitrosylate proteins in vivo and S-nitrosoglutathione (GSNO) in vitro However, a periplasmic or extracellular denitrosylase has not been identified, raising the question of how extracytoplasmic proteins are repaired after nitrosative damage. In this study, we tested whether DsbG and DsbC, two Trx family proteins that function in reducing pathways in the Escherichia coli periplasm, also possess denitrosylating activity. Both DsbG and DsbC are poorly reactive toward GSNO. Moreover, DsbG is unable to denitrosylate its specific substrate protein, YbiS. Remarkably, by borrowing the CGPC active site of E. coli Trx-1 in combination with a T200M point mutation, we transformed DsbG into an enzyme highly reactive toward GSNO and YbiS. The pKa of the nucleophilic cysteine, as well as the redox and thermodynamic properties of the engineered DsbG are dramatically changed and become similar to those of E. coli Trx-1. X-ray structural insights suggest that this results from a loss of two direct hydrogen bonds to the nucleophilic cysteine sulfur in the DsbG mutant. Our results highlight the plasticity of the Trx structural fold and reveal that the subtle change of the number of hydrogen bonds in the active site of Trx-like proteins is the key factor that thermodynamically controls reactivity toward nitrosylated compounds. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Phylogeny of the Vitamin K 2,3-Epoxide Reductase (VKOR) Family and Evolutionary Relationship to the Disulfide Bond Formation Protein B (DsbB) Family.

    Science.gov (United States)

    Bevans, Carville G; Krettler, Christoph; Reinhart, Christoph; Watzka, Matthias; Oldenburg, Johannes

    2015-07-29

    In humans and other vertebrate animals, vitamin K 2,3-epoxide reductase (VKOR) family enzymes are the gatekeepers between nutritionally acquired K vitamins and the vitamin K cycle responsible for posttranslational modifications that confer biological activity upon vitamin K-dependent proteins with crucial roles in hemostasis, bone development and homeostasis, hormonal carbohydrate regulation and fertility. We report a phylogenetic analysis of the VKOR family that identifies five major clades. Combined phylogenetic and site-specific conservation analyses point to clade-specific similarities and differences in structure and function. We discovered a single-site determinant uniquely identifying VKOR homologs belonging to human pathogenic, obligate intracellular prokaryotes and protists. Building on previous work by Sevier et al. (Protein Science 14:1630), we analyzed structural data from both VKOR and prokaryotic disulfide bond formation protein B (DsbB) families and hypothesize an ancient evolutionary relationship between the two families where one family arose from the other through a gene duplication/deletion event. This has resulted in circular permutation of primary sequence threading through the four-helical bundle protein folds of both families. This is the first report of circular permutation relating distant a-helical membrane protein sequences and folds. In conclusion, we suggest a chronology for the evolution of the five extant VKOR clades.

  4. DNA-PK. The major target for wortmannin-mediated radiosensitization by the inhibition of DSB repair via NHEJ pathway

    International Nuclear Information System (INIS)

    Hashimoto, Mitsumasa; Rao, S.; Tokuno, Osamu; Utsumi, Hiroshi; Takeda, Shunichi

    2003-01-01

    The effect of wortmannin posttreatment was studied in cells derived from different species (hamster, mouse, chicken, and human) with normal and defective DNA-dependent protein kinase (DNA-PK) activity, cells with and without the ataxia telangiectasia mutated (ATM) gene, and cells lacking other regulatory proteins involved in the DNA double-strand break (DSB) repair pathways. Clonogenic assays were used to obtain all results. Wortmannin radiosensitization was observed in Chinese hamster cells (V79-B310H, CHO-K1), mouse mammary carcinoma cells (SR-1), transformed human fibroblast (N2KYSV), chicken B lymphocyte wild-type cells (DT40), and chicken Rad54 knockout cells (Rad54 -/- ). However, mouse mammary carcinoma cells (SX9) with defects in the DNA-PK and chicken DNA-PK catalytic subunit (DNA-PKcs) knockout cells (DNA-PKcs -/-/- ) failed to exhibit wortmannin radiosensitization. On the other hand, severe combined immunodeficiency (SCID) mouse cells (SC3VA2) exposed to wortmannin exhibited significant increases in radiosensitivity, possibly because of some residual function of DNA-PKcs. Moreover, the transformed human cells derived from AT patients (AT2KYSV) and chicken ATM knockout cells (ATM -/- ) showed pronounced wortmannin radiosensitization. These studies demonstrate confirm that the mechanism underlying wortmannin radiosensitization is the inhibition of DNA-PK, but not of ATM, thereby resulting in the inhibition of DSB repair via nonhomologous endjoining (NHEJ). (author)

  5. Clustering of DSB in DNA by X-Ray and a-particle irradiation in MCF-7 cells studied with anti γ-H2AX

    International Nuclear Information System (INIS)

    Tapia, O.; Soto, J.; Castro, F.A.; Berciano, Ma T; Lafarga, M.; Cos, S.; Sanchez-Barcelo, E.

    2007-01-01

    Among the effects produced by the ionizing radiations in cellular DNA, double strand breaks (DSB) are considered particularly important. These ruptures and their grouping in certain points, clustering, are acknowledged as the cause for mutagenic effects and cellular death. In this work we present the methodology and the results of the application of the DSB - DNA marking technique by using anti γ-H2AX, taking human cancerous cells MCF-7 as model and X-rays and a particles as irradiation agents. The obtained results are showed in a qualitative way like a set of figures. Are shows the effects of a dose of 2 Gy X-rays in the DSB - DNA after 30 minutes of the irradiation that responds to a certain pattern in which a spatially homogenous irradiation interacts with the DNA. As in previous case, the effects of X-rays in the DSB - DNA shows a different pattern affecting the cells that are in mitosis. Also, the effects of a dose of 2 Gy X-rays obtained after 24 hours of irradiation shows a number of DSB smaller, which is indicative of the repairing process. The results of the irradiation with a dose of 0.1 Gy originated from a particles cause a smaller number of DSB. Nevertheless, the existence of a bigger clustering with the appearance of clearly more intense points is appraised. Also, the effect of the irradiation is showed as an aligned trace of clusters that is possible to attribute to the passing of a a particle through the cellular nucleus. (Author)

  6. Development of a radiation track structure clustering algorithm for the prediction of DNA DSB yields and radiation induced cell death in Eukaryotic cells.

    Science.gov (United States)

    Douglass, Michael; Bezak, Eva; Penfold, Scott

    2015-04-21

    The preliminary framework of a combined radiobiological model is developed and calibrated in the current work. The model simulates the production of individual cells forming a tumour, the spatial distribution of individual ionization events (using Geant4-DNA) and the stochastic biochemical repair of DNA double strand breaks (DSBs) leading to the prediction of survival or death of individual cells. In the current work, we expand upon a previously developed tumour generation and irradiation model to include a stochastic ionization damage clustering and DNA lesion repair model. The Geant4 code enabled the positions of each ionization event in the cells to be simulated and recorded for analysis. An algorithm was developed to cluster the ionization events in each cell into simple and complex double strand breaks. The two lesion kinetic (TLK) model was then adapted to predict DSB repair kinetics and the resultant cell survival curve. The parameters in the cell survival model were then calibrated using experimental cell survival data of V79 cells after low energy proton irradiation. A monolayer of V79 cells was simulated using the tumour generation code developed previously. The cells were then irradiated by protons with mean energies of 0.76 MeV and 1.9 MeV using a customized version of Geant4. By replicating the experimental parameters of a low energy proton irradiation experiment and calibrating the model with two sets of data, the model is now capable of predicting V79 cell survival after low energy (cell survival probability, the cell survival probability is calculated for each cell in the geometric tumour model developed in the current work. This model uses fundamental measurable microscopic quantities such as genome length rather than macroscopic radiobiological quantities such as alpha/beta ratios. This means that the model can be theoretically used under a wide range of conditions with a single set of input parameters once calibrated for a given cell line.

  7. Improving Fab' fragment retention in an autonucleolytic Escherichia coli strain by swapping periplasmic nuclease translocation signal from OmpA to DsbA.

    Science.gov (United States)

    Schofield, Desmond M; Sirka, Ernestas; Keshavarz-Moore, Eli; Ward, John M; Nesbeth, Darren N

    2017-12-01

    To reduce unwanted Fab' leakage from an autonucleolytic Escherichia coli strain, which co-expresses OmpA-signalled Staphylococcal nuclease and Fab' fragment in the periplasm, by substituting in Serratial nuclease and the DsbA periplasm translocation signal as alternatives. We attempted to genetically fuse a nuclease from Serratia marcescens to the OmpA signal peptide but plasmid construction failed, possibly due to toxicity of the resultant nuclease. Combining Serratial nuclease to the DsbA signal peptide was successful. The strain co-expressing this nuclease and periplasmic Fab' grew in complex media and exhibited nuclease activity detectable by DNAse agar plate but its growth in defined medium was retarded. Fab' coexpression with Staphylococcal nuclease fused to the DsbA signal peptide resulted in cells exhibiting nuclease activity and growth in defined medium. In cultivation to high cell density in a 5 l bioreactor, DsbA-fused Staphylococcal nuclease co-expression coincided with reduced Fab' leakage relative to the original autonucleolytic Fab' strain with OmpA-fused staphylococcal nuclease. We successfully rescued Fab' leakage back to acceptable levels and established a basis for future investigation of the linkage between periplasmic nuclease expression and leakage of co-expressed periplasmic Fab' fragment to the surrounding growth media.

  8. Low concentrations of antimony impair DNA damage signaling and the repair of radiation-induced DSB in HeLa S3 cells.

    Science.gov (United States)

    Koch, Barbara; Maser, Elena; Hartwig, Andrea

    2017-12-01

    Antimony is utilized in a large variety of industrial applications, leading to significant environmental and occupational exposure. Mainly based on animal experiments, the IARC and MAK Commission have classified antimony and its inorganic compounds as Group 2B or 2 carcinogens, respectively. However, the underlying mode(s) of action are still largely unknown. In the present study, we investigated the impact of non-cytotoxic up to cytotoxic concentrations of SbCl 3 on DNA DSB repair and cell cycle control in HeLa S3 cells. We induced DSB by γ-irradiation and analyzed inhibitory actions of antimony on potential molecular targets of the DSB repair machinery. Antimony disturbed cell cycle control, affecting phosphorylation of Chk1. Furthermore, the repair of DSB was impaired in the presence of antimony, as monitored by pulsed-field gel electrophoresis and γH2AX foci formation of cells in G1 and G2 phase. Specifically, BRCA1 and RAD51 were identified as molecular targets. Our results point towards an interference with both non-homologous end-joining (NHEJ) and homologous recombination (HR), and inhibitory effects may be explained by interactions with critical cysteine groups; this needs to be further investigated. Altogether, the results provide further evidence for the impairment of DNA repair processes as one underlying mechanism in antimony-induced carcinogenicity.

  9. DsbA-L prevents obesity-induced inflammation and insulin resistance by suppressing the mtDNA release-activated cGAS-cGAMP-STING pathway.

    Science.gov (United States)

    Bai, Juli; Cervantes, Christopher; Liu, Juan; He, Sijia; Zhou, Haiyan; Zhang, Bilin; Cai, Huan; Yin, Dongqing; Hu, Derong; Li, Zhi; Chen, Hongzhi; Gao, Xiaoli; Wang, Fang; O'Connor, Jason C; Xu, Yong; Liu, Meilian; Dong, Lily Q; Liu, Feng

    2017-11-14

    Chronic inflammation in adipose tissue plays a key role in obesity-induced insulin resistance. However, the mechanisms underlying obesity-induced inflammation remain elusive. Here we show that obesity promotes mtDNA release into the cytosol, where it triggers inflammatory responses by activating the DNA-sensing cGAS-cGAMP-STING pathway. Fat-specific knockout of disulfide-bond A oxidoreductase-like protein (DsbA-L), a chaperone-like protein originally identified in the mitochondrial matrix, impaired mitochondrial function and promoted mtDNA release, leading to activation of the cGAS-cGAMP-STING pathway and inflammatory responses. Conversely, fat-specific overexpression of DsbA-L protected mice against high-fat diet-induced activation of the cGAS-cGAMP-STING pathway and inflammation. Taken together, we identify DsbA-L as a key molecule that maintains mitochondrial integrity. DsbA-L deficiency promotes inflammation and insulin resistance by activating the cGAS-cGAMP-STING pathway. Our study also reveals that, in addition to its well-characterized roles in innate immune surveillance, the cGAS-cGAMP-STING pathway plays an important role in mediating obesity-induced metabolic dysfunction.

  10. Electric Co'Co' bi-voltage locomotive class EG 3100 of DSB; Co'Co'-Zweifrequenzlokomotive EG 3100 fuer Danske Statsbaner

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, B.O. [DSB Materiel Technik, Copenhagen (Denmark); Joergensen, O.A. [Siemens AG, Erlangen (Germany). Abt. VT 62; Proell, J. [Siemens AG, Muenchen (Germany). Abt. VT 68

    2000-12-01

    DSB has purchased a series of heavy electric locomotives for hauling transit freight trains between Central Europe and Scandinavia. Demands, basic features and technical components are described in detail. (orig.) [German] Fuer den Transitgueterverkehr zwischen Mitteleuropa und Skandinavien hat Danske Statsbaner eine Serie schwerer elektrischer Lokomotiven beschafft. Die Anforderungen, das Grundkonzept und die technischen Komponenten werden ausfuehrlich beschrieben. (orig.)

  11. Electric Co'Co' bi-voltage locomotive class EG 3100 of DSB; Co'Co'-Zweifrequenzlokomotive EG 3100 fuer Danske Statsbaner

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, B.O. [DSB Materiel Technik, Copenhagen (Denmark); Joergensen, O.A. [Siemens AG, Erlangen (Germany). Abt. VT 62; Proell, G. [Siemens AG, Muenchen (Germany). Abt. VT 68

    2001-07-01

    DSB has purchased a series of heavy electric locomotives for hauling transit freight trains between Central Europe and Scandinavia. Demands, basic features and technical components are described in detail. (orig.) [German] Fuer den Transitgueterverkehr zwischen Mitteleuropa und Skandinavien hat Danske Statsbaner eine Serie schwerer elektrischer Lokomotiven beschafft. Die Anforderungen, das Grundkonzept und die technischen Komponenten werden ausfuehrlich beschrieben. (orig.)

  12. DTU’s undersøgelser af lav adhæsion / glatte skinner for Transportministeriet og DSB

    DEFF Research Database (Denmark)

    Stockmarr, Anders; Ersbøll, Bjarne Kjær; Kotwa, Ewelina Katarzyna

    Nærværende undersøgelse af forekomsten af lav adhæsion / ”glatte skinner” er en opfølgning på DTU’s undersøgelser af IC4 togenes bremseadfærd ved Marslev den 7. november 2011, som blev gennemført for Transportministeriet og DSB i perioden april - juni 2012, og som konkluderede at den helt...... overvejende årsag til IC4 togets lange standselængde ved Marslev-hændelsen var lav adhæsion, det vil sige ”glathed” mellem hjul og skinner. Afledt af dette resultat er der opstået en interesse og et behov for en bredere analyse af sikkerhedskritiske faktorer i forbindelse med togdrift, som belyser fænomenet...... at gennemføre nedenstående tre udredningsopgaver, som DTU har gennemført i perioden oktober 2012 – oktober 2013: •En erfaringsindsamling med henblik på, hvordan andre lande i Nord- og Mellemeuropa håndterer lav adhæsion / ”glatte skinner”. •En systematisk kortlægning af hyppighed og omfang af lav adhæsion...

  13. Choreography of recombination proteins during the DNA damage response

    DEFF Research Database (Denmark)

    Lisby, Michael; Rothstein, Rodney

    2009-01-01

    Genome integrity is frequently challenged by DNA lesions from both endogenous and exogenous sources. A single DNA double-strand break (DSB) is lethal if unrepaired and may lead to loss of heterozygosity, mutations, deletions, genomic rearrangements and chromosome loss if repaired improperly. Such...... research. Here we review the cell biological response to DSBs in mitotically growing cells with an emphasis on homologous recombination pathways in yeast Saccharomyces cerevisiae and in mammalian cells....

  14. In normal human fibroblasts variation in DSB repair capacity cannot be ascribed to radiation-induced changes in the localisation, expression or activity of major NHEJ proteins

    DEFF Research Database (Denmark)

    Kasten-Pisula, Ulla; Vronskaja, Svetlana; Overgaard, Jens

    2008-01-01

    in the activity of the DNA-PK complex induced upon irradiation. CONCLUSIONS: For normal human fibroblasts, the level or activity of NHEJ proteins measured prior to or after irradiation cannot be used to predict the DSB repair capacity or cellular radiosensitivity. Udgivelsesdato: 2008-Mar......BACKGROUND AND PURPOSE: The aim of the present study was to test whether for normal human fibroblasts the variation in double-strand break (DSB) repair capacity results from radiation-induced differences in localisation, expression or activity of major non-homologous end-joining (NHEJ) proteins....... MATERIALS AND METHODS: Experiments were performed with 11 normal human fibroblast strains AF01-11. NHEJ proteins were determined by Western blot and DNA-PK activity by pulldown-assay. RESULTS: The four NHEJ proteins tested (Ku70, Ku80, XRCC4 and DNA-PKcs) were found to be localised almost exclusively...

  15. Acute Normal Tissue Reactions in Head-and-Neck Cancer Patients Treated With IMRT: Influence of Dose and Association With Genetic Polymorphisms in DNA DSB Repair Genes

    International Nuclear Information System (INIS)

    Werbrouck, Joke; Ruyck, Kim de; Duprez, Frederic; Veldeman, Liv; Claes, Kathleen; Eijkeren, Marc van; Boterberg, Tom; Willems, Petra; Vral, Anne; Neve, Wilfried de; Thierens, Hubert

    2009-01-01

    Purpose: To investigate the association between dose-related parameters and polymorphisms in DNA DSB repair genes XRCC3 (c.-1843A>G, c.562-14A>G, c.722C>T), Rad51 (c.-3429G>C, c.-3392G>T), Lig4 (c.26C>T, c.1704T>C), Ku70 (c.-1310C>G), and Ku80 (c.2110-2408G>A) and the occurrence of acute reactions after radiotherapy. Materials and Methods: The study population consisted of 88 intensity-modulated radiation therapy (IMRT)-treated head-and-neck cancer patients. Mucositis, dermatitis, and dysphagia were scored using the Common Terminology Criteria (CTC) for Adverse Events v.3.0 scale. The population was divided into a CTC0-2 and CTC3+ group for the analysis of each acute effect. The influence of the dose on critical structures was analyzed using dose-volume histograms. Genotypes were determined by polymerase chain reaction (PCR) combined with restriction fragment length polymorphism or PCR-single base extension assays. Results: The mean dose (D mean ) to the oral cavity and constrictor pharyngeus (PC) muscles was significantly associated with the development of mucositis and dysphagia, respectively. These parameters were considered confounding factors in the radiogenomics analyses. The XRCC3c.722CT/TT and Ku70c.-1310CG/GG genotypes were significantly associated with the development of severe dysphagia (CTC3+). No association was found between the investigated polymorphisms and the development of mucositis or dermatitis. A risk analysis model for severe dysphagia, which was developed based on the XRCC3c.722CT/TT and Ku70c.-1310CG/GG genotypes and the PC dose, showed a sensitivity of 78.6% and a specificity of 77.6%. Conclusions: The XRCC3c.722C>T and Ku70c.-1310C>G polymorphisms as well as the D mean to the PC muscles were highly associated with the development of severe dysphagia after IMRT. The prediction model developed using these parameters showed a high sensitivity and specificity

  16. The Thioredoxin Domain of Neisseria Gonorrhoeae PilB can use Electrons from DsbD to Reduce Downstream Methionine Sulfoxide Reductases

    Energy Technology Data Exchange (ETDEWEB)

    Brot,N.; Collet, J.; Johnson, L.; Jonsson, T.; Weissbach, H.; Lowther, W.

    2006-01-01

    The PilB protein from Neisseria gonorrhoeae is located in the periplasm and made up of three domains. The N-terminal, thioredoxin-like domain (NT domain) is fused to tandem methionine sulfoxide reductase A and B domains (MsrA/B). We show that the {alpha} domain of Escherichia coli DsbD is able to reduce the oxidized NT domain, which suggests that DsbD in Neisseria can transfer electrons from the cytoplasmic thioredoxin to the periplasm for the reduction of the MsrA/B domains. An analysis of the available complete genomes provides further evidence for this proposition in other bacteria where DsbD/CcdA, Trx, MsrA, and MsrB gene homologs are all located in a gene cluster with a common transcriptional direction. An examination of wild-type PilB and a panel of Cys to Ser mutants of the full-length protein and the individually expressed domains have also shown that the NT domain more efficiently reduces the MsrA/B domains when in the polyprotein context. Within this framework there does not appear to be a preference for the NT domain to reduce the proximal MsrA domain over MsrB domain. Finally, we report the 1.6 {angstrom} crystal structure of the NT domain. This structure confirms the presence of a surface loop that makes it different from other membrane-tethered, Trx-like molecules including TlpA, CcmG and ResA. Subtle differences are observed in this loop when compared to the N. meningitidis NT domain structure. The data taken together supports the formation of specific NT domain interactions with the MsrA/B domains and its in vivo recycling partner, DsbD.

  17. γH2AX foci as a marker for DNA double-strand breaks

    International Nuclear Information System (INIS)

    Deckbar, Dorothee

    2009-01-01

    Full text: The DNA double-strand break (DSB) is the most deleterious lesion of all DNA damages. Left unrepaired or being mis-rejoined it can lead to chromosome aberrations which compromise the genomic stability and carry the potential to initiate carcinogenesis. So DSB repair mechanisms are under intensive investigation for many years. As older techniques had to utilize non-physiological doses to monitor DSB repair, they did not allow repair studies on the cellular level or after in vivo irradiation. But during the last years, an upcoming method allows the detection of a single DSB after physiologically relevant doses. To maintain the genomic integrity after the occurrence of a DSB, cellular mechanisms have evolved that detect and repair DSBs and even halt cell cycle progression to provide time for repair. In these processes, one of the first steps is the phosphorylation of the histone H2AX at serine 139 (γH2AX). Within minutes after DSB induction, large numbers of H2AX molecules are phosphorylated around the break site leading to the accumulation of proteins involved in chromatin remodelling, to damage signal amplification, and eventually to checkpoint activation and DSB repair. The finding that DSB-surrounding proteins can be visualized as foci in immunofluorescence microscopy opened up new opportunities in cancer biology and radiation biology. It was now for the first time possible to measure DSB repair after physiologically relevant doses of ionizing radiation, i.e. after doses used for therapeutic as well as for diagnostic purposes. First reports even describe the measurement of DSB repair after in vivo irradiation in mice and humans. This did not only improve the basic research investigating the mechanisms of DSB repair but also the research on low-dose effects and radiation protection. So the potential of γH2AX foci analysis as a predictive marker for radiosensitivity or radiation induced side effects is actually discussed. (author)

  18. Plant γH2AX foci are required for proper DNA DSB repair responses and colocalize with E2F factors

    OpenAIRE

    Smetana, Ondrej; Sanchez-Calderon, Lenin; Lincker, Frédéric; Genestier, Julie; Schmit, Anne-Catherine; Houlné, Guy; Chabouté, Marie Edith

    2012-01-01

    Cellular responses to DNA double-strand breaks (DSBs) are linked in mammals and yeasts to the phosphorylated histones H2AX (cH2AX) repair foci which are multiproteic nuclear complexes responsible for DSB sensing and signalling. However, neither the components of these foci nor their role are yet known in plants. In this paper, we describe the effects of cH2AX deficiency in Arabidopsis thaliana plants challenged with DSBs in terms of genotoxic sensitivity and E2F-mediated transcriptional respo...

  19. The inhibition of assembly of HIV-1 virus-like particles by 3-O-(3',3'-dimethylsuccinyl betulinic acid (DSB is counteracted by Vif and requires its Zinc-binding domain

    Directory of Open Access Journals (Sweden)

    Bouaziz Serge

    2008-12-01

    Full Text Available Abstract Background DSB, the 3-O-(3',3'dimethylsuccinyl derivative of betulinic acid, blocks the last step of protease-mediated processing of HIV-1 Gag precursor (Pr55Gag, which leads to immature, noninfectious virions. When administered to Pr55Gag-expressing insect cells (Sf9, DSB inhibits the assembly and budding of membrane-enveloped virus-like particles (VLP. In order to explore the possibility that viral factors could modulate the susceptibility to DSB of the VLP assembly process, several viral proteins were coexpressed individually with Pr55Gag in DSB-treated cells, and VLP yields assayed in the extracellular medium. Results Wild-type Vif (Vifwt restored the VLP production in DSB-treated cells to levels observed in control, untreated cells. DSB-counteracting effect was also observed with Vif mutants defective in encapsidation into VLP, suggesting that packaging and anti-DSB effect were separate functions in Vif. The anti-DSB effect was abolished for VifC133S and VifS116V, two mutants which lacked the zinc binding domain (ZBD formed by the four H108C114C133H139 coordinates with a Zn atom. Electron microscopic analysis of cells coexpressing Pr55Gag and Vifwt showed that a large proportion of VLP budded into cytoplasmic vesicles and were released from Sf9 cells by exocytosis. However, in the presence of mutant VifC133S or VifS116V, most of the VLP assembled and budded at the plasma membrane, as in control cells expressing Pr55Gag alone. Conclusion The function of HIV-1 Vif protein which negated the DSB inhibition of VLP assembly was independent of its packaging capability, but depended on the integrity of ZBD. In the presence of Vifwt, but not with ZBD mutants VifC133S and VifS116V, VLP were redirected to a vesicular compartment and egressed via the exocytic pathway.

  20. Aberrant overexpression of miR-421 downregulates ATM and leads to a pronounced DSB repair defect and clinical hypersensitivity in SKX squamous cell carcinoma

    International Nuclear Information System (INIS)

    Mansour, Wael Y.; Bogdanova, Natalia V.; Kasten-Pisula, Ulla; Rieckmann, Thorsten; Köcher, Sabrina; Borgmann, Kerstin; Baumann, Michael; Krause, Mechtild; Petersen, Cordula; Hu, Hailiang; Gatti, Richard A.; Dikomey, Ekkehard; Dörk, Thilo; Dahm-Daphi, Jochen

    2013-01-01

    Background: Cellular and clinical sensitivity to ionizing radiation (IR) is determined by DNA double-strand breaks (DSB) repair. Here, we investigate the molecular mechanism underlying the extreme response of a head and neck tumor case (SKX) to standard radiotherapy. Methods: Immunofluorescence (IF) was used for the assessment of DSB repair, Western blot and real-time PCR for protein and mRNA expression, respectively. Results: SKX cells exhibited a pronounced radiosensitivity associated with numerous residual γ-H2AX foci after IR. This was not associated with lacking canonical repair proteins. SKX cells did not express any ATM protein. Accordingly, immunoblotting revealed no ATM kinase activity toward substrates such as p-SMC1, p-CHK2 and p-KAP1. Sequencing of all 66 exons of ATM showed no mutation. ATM mRNA level was moderately reduced, which could be reverted by 5′-Aza-C treatment but without restoring protein levels. Importantly, we demonstrated a post-transcriptional regulation in SKX cells via 6-fold enhanced levels of miR-421, which targets the 3′-UTR of ATM mRNA. Transfection of SKX cells with either anti-miR-421 inhibitor or a microRNA-insensitive ATM vector recovered ATM expression and abrogated the hyper-radiosensitivity. Conclusion: This is the first report describing microRNA-mediated down-regulation of ATM leading to clinically manifest tumor radiosensitivity

  1. TU-EF-304-10: Efficient Multiscale Simulation of the Proton Relative Biological Effectiveness (RBE) for DNA Double Strand Break (DSB) Induction and Bio-Effective Dose in the FLUKA Monte Carlo Radiation Transport Code

    Energy Technology Data Exchange (ETDEWEB)

    Moskvin, V; Tsiamas, P; Axente, M; Farr, J [St. Jude Children’s Research Hospital, Memphis, TN (United States); Stewart, R [University of Washington, Seattle, WA. (United States)

    2015-06-15

    Purpose: One of the more critical initiating events for reproductive cell death is the creation of a DNA double strand break (DSB). In this study, we present a computationally efficient way to determine spatial variations in the relative biological effectiveness (RBE) of proton therapy beams within the FLUKA Monte Carlo (MC) code. Methods: We used the independently tested Monte Carlo Damage Simulation (MCDS) developed by Stewart and colleagues (Radiat. Res. 176, 587–602 2011) to estimate the RBE for DSB induction of monoenergetic protons, tritium, deuterium, hellium-3, hellium-4 ions and delta-electrons. The dose-weighted (RBE) coefficients were incorporated into FLUKA to determine the equivalent {sup 6}°60Co γ-ray dose for representative proton beams incident on cells in an aerobic and anoxic environment. Results: We found that the proton beam RBE for DSB induction at the tip of the Bragg peak, including primary and secondary particles, is close to 1.2. Furthermore, the RBE increases laterally to the beam axis at the area of Bragg peak. At the distal edge, the RBE is in the range from 1.3–1.4 for cells irradiated under aerobic conditions and may be as large as 1.5–1.8 for cells irradiated under anoxic conditions. Across the plateau region, the recorded RBE for DSB induction is 1.02 for aerobic cells and 1.05 for cells irradiated under anoxic conditions. The contribution to total effective dose from secondary heavy ions decreases with depth and is higher at shallow depths (e.g., at the surface of the skin). Conclusion: Multiscale simulation of the RBE for DSB induction provides useful insights into spatial variations in proton RBE within pristine Bragg peaks. This methodology is potentially useful for the biological optimization of proton therapy for the treatment of cancer. The study highlights the need to incorporate spatial variations in proton RBE into proton therapy treatment plans.

  2. Understanding the -C-X1-X2-C- motif in the active site of the thioredoxin superfamily: E. coli DsbA and its mutants as a model system.

    Science.gov (United States)

    Karshikoff, Andrey; Nilsson, Lennart; Foloppe, Nicolas

    2013-08-27

    E. coli DsbA is an intensively studied enzyme of the thioredoxin superfamily of thiol-disulfide oxidoreductases. DsbA catalyzes the disulfide bond formation and folding of proteins in the bacterial periplasm. DsbA and its mutants have highlighted the strong and puzzling influence of the -C-X1-X2-C- active site variants, found across the thioredoxin superfamily, on the ionization and redox properties of this site. However, the interpretation of these observations remains wanting, largely due to a dearth of structural information. Here, molecular dynamics simulations are used to provide extensive information on the structure and dynamics of reduced -C30-X31-X32-C33- motifs in wild type DsbA and 13 of its mutants. These simulations are combined with calculations of the pK of H32 and of the very low pK of the catalytic cysteine C30. In wild type DsbA, the titrations of C30 and H32 are shown to be coupled; the protonation states and dynamics of H32 are examined. The thiolate of C30 is stabilized by hydrogen bonds with the protein. Modulation of these hydrogen bonds by alteration of residue X32 has the greatest impact on the pK of C30, which rationalizes its higher pK in thioredoxin and tryparedoxin. Because of structural constrains, residue X31 has only an indirect and weak influence on the pK of C30. The dynamics of C30 is clearly related to its stabilizing interactions and pK value. Although relatively small differences between pKs were not reproduced in the calculations, the major trends are explained, adding new insights to our understanding of enzymes in this family.

  3. Mammalian DNA single-strand break repair: an X-ra(y)ted affair.

    Science.gov (United States)

    Caldecott, K W

    2001-05-01

    The genetic stability of living cells is continuously threatened by the presence of endogenous reactive oxygen species and other genotoxic molecules. Of particular threat are the thousands of DNA single-strand breaks that arise in each cell, each day, both directly from disintegration of damaged sugars and indirectly from the excision repair of damaged bases. If un-repaired, single-strand breaks can be converted into double-strand breaks during DNA replication, potentially resulting in chromosomal rearrangement and genetic deletion. Consequently, cells have adopted multiple pathways to ensure the rapid and efficient removal of single-strand breaks. A general feature of these pathways appears to be the extensive employment of protein-protein interactions to stimulate both the individual component steps and the overall repair reaction. Our current understanding of DNA single-strand break repair is discussed, and testable models for the architectural coordination of this important process are presented. Copyright 2001 John Wiley & Sons, Inc.

  4. Effects of 3-Deoxyadenosine (Cordycepin) on the repair of X-ray-induced DNA single- and double-strand breaks in chinese hamster V79 cells

    International Nuclear Information System (INIS)

    Hiraoka, Wakako; Kuwabara, Mikinori; Sato, Fumiaki

    1990-01-01

    The ability of cordycepin to inhibit the repair of DNA strand breaks was examined with X-irradiated Chinese hamster V79 cells in log-phase culture. A filter elution technique revealed that 70 μM cordycepin did not inhibit the repair of single-strand breaks but inhibited the repair of double-strand breaks. These findings confirmed the fact that the increase in the lethality of cordycepin in X-irradiated cultured mammalian cells was attributable to unrepaired DNA double-strand breaks. (author)

  5. Accumulation of DNA Double-Strand Breaks in Normal Tissues After Fractionated Irradiation

    International Nuclear Information System (INIS)

    Ruebe, Claudia E.; Fricke, Andreas; Wendorf, Juliane; Stuetzel, Annika; Kuehne, Martin; Ong, Mei Fang; Lipp, Peter; Ruebe, Christian

    2010-01-01

    Purpose: There is increasing evidence that genetic factors regulating the recognition and/or repair of DNA double-strand breaks (DSBs) are responsible for differences in radiosensitivity among patients. Genetically defined DSB repair capacities are supposed to determine patients' individual susceptibility to develop adverse normal tissue reactions after radiotherapy. In a preclinical murine model, we analyzed the impact of different DSB repair capacities on the cumulative DNA damage in normal tissues during the course of fractionated irradiation. Material and Methods: Different strains of mice with defined genetic backgrounds (SCID -/- homozygous, ATM -/- homozygous, ATM +/- heterozygous, and ATM +/+ wild-type mice) were subjected to single (2 Gy) or fractionated irradiation (5 x 2 Gy). By enumerating γH2AX foci, the formation and rejoining of DSBs were analyzed in organs representative of both early-responding (small intestine) and late-responding tissues (lung, kidney, and heart). Results: In repair-deficient SCID -/- and ATM -/- homozygous mice, large proportions of radiation-induced DSBs remained unrepaired after each fraction, leading to the pronounced accumulation of residual DNA damage after fractionated irradiation, similarly visible in early- and late-responding tissues. The slight DSB repair impairment of ATM +/- heterozygous mice was not detectable after single-dose irradiation but resulted in a significant increase in unrepaired DSBs during the fractionated irradiation scheme. Conclusions: Radiation-induced DSBs accumulate similarly in acute- and late-responding tissues during fractionated irradiation, whereas the whole extent of residual DNA damage depends decisively on the underlying genetically defined DSB repair capacity. Moreover, our data indicate that even minor impairments in DSB repair lead to exceeding DNA damage accumulation during fractionated irradiation and thus may have a significant impact on normal tissue responses in clinical

  6. The studies of DNA double-strand break (DSB) rejoining and mRNA expression of repair gene XRCCs in malignant transformed cell lines of human bronchial epithelial cells generated by α-particles

    International Nuclear Information System (INIS)

    Sun Jingfen; Sui Jianli; Geng Yu; Zhou Pingkun; Wu Dechang

    2002-01-01

    Objective: To investigate the efficiency of γ-ray-induced DNA DSB rejoining and the mRNA expression of DNA repair genes in malignantly transformed cell lines of human bronchial epithelial cells generated by exposure to a-particles. Methods: Pulsed field gel electrophoresis (PFGE) was used to detect DNA. DSBs mRNA expression was analyzed by RT-PCR. Results: The residual DNA DSB damage level after 4hrs repair following 0-150 Gy of γ-irradiation in the malignantly transformed cell lines BERP35T-1 and BERP35T-4 was significantly higher than that in their parental BEP2D cells. The analysis of mRNA level revealed a 2.5-to 6.5-fold down-regulated expression of the DNA repair genes XRCC-2, XRCC-3 and Ku80 (XRCC-5) in BERP35T-1 and BERP35T-4 cells as compared with the parental BEP2D cells. In contrast, the expression of DNA-PKcs(XRCC7) was 2.4-fold up-regulated in the transformed cell line BERP35T-4, in which there was a significantly higher proportion of polyploid cells. Conclusion: This study results show that the deficiency of DNA DSB rejoining and depressed mRNA expression of DNA repair genes could be involved in the malignant transformation process of BEP2D cells induced by exposure to α-particles

  7. The oxygen enhancement ratio for single- and double-strand breaks induced by tritium incorporated in DNA of cultured human T1 cells. Impact of the transmutation effect.

    Science.gov (United States)

    Tisljar-Lentulis, G; Henneberg, P; Feinendegen, L E; Commerford, S L

    1983-04-01

    The effect of oxygen, expressed as the oxygen enhancement ratio (OER), on the number of single-strand breaks (SSB) and double-strand breaks (DSB) induced in DNA by the radioactive decay of tritium was measured in human T1 cells whose DNA had been labeled with tritium at carbon atom number 6 of thymidine. Decays were accumulated in vivo under aerobic conditions at 0-1 degrees C and at -196 degrees C and in a nitrogen atmosphere at 0-1 degrees C. The number of SSB and DSB produced was analyzed by sucrose gradient centrifugation. For each tritium decay there were 0.25 DSB in cells exposed to air at 0-1 degrees C and 0.07 in cells kept under nitrogen, indicating an OER of 3.6, a value expected for such low-LET radiation. However, for each tritium decay there were 1.25 SSB in cells exposed to air at 0-1 degrees C and 0.76 in cells kept under nitrogen indicating an OER of only 1.7. The corresponding values for 60Co gamma radiation, expressed as SSB per 100 eV absorbed energy, were 4.5 and 1.0, giving an OER of 4.5. The low OER value found for SSB induced by tritium decay can be explained if 31% of the total SSB produced in air result from transmutation by a mechanism which does not produce DSB and is unaffected by oxygen.

  8. MO-FG-CAMPUS-TeP3-02: Benchmarks of a Proton Relative Biological Effectiveness (RBE) Model for DNA Double Strand Break (DSB) Induction in the FLUKA, MCNP, TOPAS, and RayStation™ Treatment Planning System

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, R [University of Washington, Seattle, WA (United States); Streitmatter, S [University of Utah Hospitals, Salt Lake City, UT (United States); Traneus, E [RAYSEARCH LABORATORIES AB, Stockholm (Sweden); Moskvin, V [St. Jude Children’s Hospital, Memphis, TN (United States); Schuemann, J [Massachusetts General Hospital, Boston, MA (United States)

    2016-06-15

    Purpose: Validate implementation of a published RBE model for DSB induction (RBEDSB) in several general purpose Monte Carlo (MC) code systems and the RayStation™ treatment planning system (TPS). For protons and other light ions, DSB induction is a critical initiating molecular event that correlates well with the RBE for cell survival. Methods: An efficient algorithm to incorporate information on proton and light ion RBEDSB from the independently tested Monte Carlo Damage Simulation (MCDS) has now been integrated into MCNP (Stewart et al. PMB 60, 8249–8274, 2015), FLUKA, TOPAS and a research build of the RayStation™ TPS. To cross-validate the RBEDSB model implementation LET distributions, depth-dose and lateral (dose and RBEDSB) profiles for monodirectional monoenergetic (100 to 200 MeV) protons incident on a water phantom are compared. The effects of recoil and secondary ion production ({sub 2}H{sub +}, {sub 3}H{sub +}, {sub 3}He{sub 2+}, {sub 4}He{sub 2+}), spot size (3 and 10 mm), and transport physics on beam profiles and RBEDSB are examined. Results: Depth-dose and RBEDSB profiles among all of the MC models are in excellent agreement using a 1 mm distance criterion (width of a voxel). For a 100 MeV proton beam (10 mm spot), RBEDSB = 1.2 ± 0.03 (− 2–3%) at the tip of the Bragg peak and increases to 1.59 ± 0.3 two mm distal to the Bragg peak. RBEDSB tends to decrease as the kinetic energy of the incident proton increases. Conclusion: The model for proton RBEDSB has been accurately implemented into FLUKA, MCNP, TOPAS and the RayStation™TPS. The transport of secondary light ions (Z > 1) has a significant impact on RBEDSB, especially distal to the Bragg peak, although light ions have a small effect on (dosexRBEDSB) profiles. The ability to incorporate spatial variations in proton RBE within a TPS creates new opportunities to individualize treatment plans and increase the therapeutic ratio. Dr. Erik Traneus is employed full-time as a Research Scientist

  9. DSB Task Force on Cyber Supply Chain

    Science.gov (United States)

    2017-04-01

    established to provide independent advice to the Secretary of Defense. Statements, opinions, conclusions, and recommendations in this report do not...that does not rely exclusively on trust; and continue research and development (R&D) investments of DoD agencies for a technology-enabled strategy...subcontracts. Such reporting requirements are inconsistent and no DoD system at present collects event information on cyber-physical attacks of electronic

  10. DSB Task Force on Cyber Supply Chain

    Science.gov (United States)

    2017-02-06

    Abbreviations and Acronyms iii Acronyms and Abbreviations ACQ: acquisition management AIS : Automated Indicator Sharing AMRAAM: Advanced...situational awareness to enable mission planners and commanders to recognize the danger presented potential attacks prior to missions and to develop...and disseminate information reported pursuant to CISA, DHS operates an Automated Indicator Sharing ( AIS ) system within the National Cybersecurity and

  11. Double strand break repair: two mechanisms in competition but tightly linked to cell cycle

    International Nuclear Information System (INIS)

    Delacote, F.

    2002-11-01

    DNA double strand breaks (DSB) are highly toxic damage although they can be induced to create genetic diversity. Two distinct pathways can repair DSB: Homologous Recombination (HR) and Non Homologous End Joining (NHEJ). If un- or mis-repaired, this damage can lead to cancer. Thus, it is essential to investigate how these two pathways are regulated for DSB repair. NHEJ inhibition leads to HR DSB repair stimulation. However, this channeling to HR is tightly linked to cell cycle since NHEJ and HR are active in G1/early S and late S/G2, respectively. Our results suggest that G1-unrepaired DSB go through S phase to be repaired by HR in G2. Those results allow a better understanding of DSB repair mechanisms regulation. (author)

  12. 25–34 GHz Single-Pole, Double-Throw CMOS Switches for a Ka-Band Phased-Array Transceiver

    Directory of Open Access Journals (Sweden)

    Sangyong Park

    2018-01-01

    Full Text Available This paper presents two single-pole, double-throw (SPDT mm-wave switches for Ka-band phased-array transceivers, fabricated with a 65-nm complementary metal oxide semiconductor (CMOS process. One switch employs cross-biasing (CB control with a single supply, while the other uses dual-supply biasing (DSB control with positive and negative voltages. Negative voltages were generated internally, using a ring oscillator and a charge pump. Identical gate and body floated N-type metal oxide semiconductor field effect transistors (N-MOSFETs in a triple well were used as the switch core transistors. Inductors were used to improve the isolation between the transmitter (TX and receiver (RX, as well as insertion loss, by canceling the parasitic capacitance of the switch core transistors at resonance. The size of the proposed radio frequency (RF switch is 260 μm × 230 μm, excluding all pads. The minimum insertion losses of the CB and DSB switches were 2.1 dB at 28 GHz and 1.93 dB at 24 GHz, respectively. Between 25 GHz and 34 GHz, the insertion losses were less than 2.3 dB and 2.5 dB, the return losses were less than 16.7 dB and 17.3 dB, and the isolation was over 18.4 dB and 15.3 dB, respectively. The third order input intercept points (IIP3 of the CB and DSB switches were 38.4 dBm and 39 dBm at 28 GHz, respectively.

  13. Induction and repair of double- and single-strand DNA breaks in bacteriophage lambda superinfecting Escherichia coli

    International Nuclear Information System (INIS)

    Boye, E.; Krisch, R.E.

    1980-01-01

    Induction and repair of double-and single-strand DNA breaks have been measured after decays of 125 I and 3 H incorporated into the DNA and after external irradiation with 4 MeV electrons. For the decay experiments, cells of wild type Escherichia coli K-12 were superinfected with bacteriophage lambda DNA labelled with 5'-( 125 I)iodo-2'-deoxyuridine or with (methyl- 3 H)thymidine and frozen in liquid nitrogen. Aliquots were thawed at intervals and lysed at neutral pH, and the phage DNA was assayed for double- and single-strand breakage by neutral sucrose gradient centrifugation. The gradients used allowed measurements of both kinds of breaks in the same gradient. Decays of 125 I induced 0.39 single-strand breaks per double-strand break. No repair of either break type could be detected. Each 3 H disintegration caused 0.20 single-strand breaks and very few double-strand breaks. The single-strand breaks were rapidly rejoined after the cells were thawed. For irradiation with 4 MeV electrons, cells of wild type E. coli K-12 were superinfected with phage lambda and suspended in growth medium. Irradiation induced 42 single-strand breaks per double-strand break. The rates of break induction were 6.75 x 10 -14 (double-strand breaks) and 2.82 x 10 -12 (single-strand breaks) per rad and per dalton. The single-strand breaks were rapidly repaired upon incubation whereas the double-strand breaks seemed to remain unrepaired. It is concluded that double-strand breaks in superinfecting bacteriophage lambda DNA are repaired to a very small extent, if at all. (Author)

  14. Single-strand DNA-binding protein SSB1 facilitates TERT recruitment to telomeres and maintains telomere G-overhangs.

    Science.gov (United States)

    Pandita, Raj K; Chow, Tracy T; Udayakumar, Durga; Bain, Amanda L; Cubeddu, Liza; Hunt, Clayton R; Shi, Wei; Horikoshi, Nobuo; Zhao, Yong; Wright, Woodring E; Khanna, Kum Kum; Shay, Jerry W; Pandita, Tej K

    2015-03-01

    Proliferating mammalian stem and cancer cells express telomerase [telomerase reverse transcriptase (TERT)] in an effort to extend chromosomal G-overhangs and maintain telomere ends. Telomerase-expressing cells also have higher levels of the single-stranded DNA-binding protein SSB1, which has a critical role in DNA double-strand break (DSB) repair. Here, we report that SSB1 binds specifically to G-strand telomeric DNA in vitro and associates with telomeres in vivo. SSB1 interacts with the TERT catalytic subunit and regulates its interaction with telomeres. Deletion of SSB1 reduces TERT interaction with telomeres and leads to G-overhang loss. Although SSB1 is recruited to DSB sites, we found no corresponding change in TERT levels at these sites, implying that SSB1-TERT interaction relies upon a specific chromatin structure or context. Our findings offer an explanation for how telomerase is recruited to telomeres to facilitate G-strand DNA extension, a critical step in maintaining telomere ends and cell viability in all cancer cells. Cancer Res; 75(5); 858-69. ©2015 AACR. ©2015 American Association for Cancer Research.

  15. Repair of single-strand breaks induced in the DNA of Proteus mirabilis by excision repair after UV-irradiation

    International Nuclear Information System (INIS)

    Stoerl, K.; Mund, C.

    1977-01-01

    Single-strand breaks have been produced in the DNA of P. mirabilis after UV-irradiation in dependence on the incident UV-doses. It has been found that there exists a discrepancy between the single-strand breaks estimated from sedimentation in alkaline sucrose gradients and the expected single-strand breaks approximated from measurements of dimer excision. The low number in incision breaks observed by sedimentation experiments is an indication that the cells are able to repair the excision-induced breaks as fast as they are formed. Toluenized cells have been used for investigation of the incision step independently of subsequent repair processes. In presence of NMN the appearance of more single-strand breaks in the DNA has been observed. Furthermore, the number of incision breaks in toluenized cells increased in presence of exogenous ATP. The completion of the excision repair process has been investigated by observing the rejoining of incision breaks. After irradiation with UV-doses higher than approximately 240 erg/mm 2 the number of single-strand breaks remaining unrepaired in the DNA increased. Studies of the influence of nutrition conditions on the repair process have shown approximately the same capacity for repair of single-strand breaks in growth medium as well as in buffer. Progress in the excision repair was also followed by investigation of the DNA synthesized at the template-DNA containing the pyrimidine dimers. In comparison with E. coli, P. mirabilis showed a somewhat lower efficiency for the repair of single-strand breaks during the excision repair. (author)

  16. single crystals

    Indian Academy of Sciences (India)

    2018-05-18

    May 18, 2018 ... Abstract. 4-Nitrobenzoic acid (4-NBA) single crystals were studied for their linear and nonlinear optical ... studies on the proper growth, linear and nonlinear optical ..... between the optic axes and optic sign of the biaxial crystal.

  17. Double-strand break repair-adox: Restoration of suppressed double-strand break repair during mitosis induces genomic instability.

    Science.gov (United States)

    Terasawa, Masahiro; Shinohara, Akira; Shinohara, Miki

    2014-12-01

    Double-strand breaks (DSBs) are one of the severest types of DNA damage. Unrepaired DSBs easily induce cell death and chromosome aberrations. To maintain genomic stability, cells have checkpoint and DSB repair systems to respond to DNA damage throughout most of the cell cycle. The failure of this process often results in apoptosis or genomic instability, such as aneuploidy, deletion, or translocation. Therefore, DSB repair is essential for maintenance of genomic stability. During mitosis, however, cells seem to suppress the DNA damage response and proceed to the next G1 phase, even if there are unrepaired DSBs. The biological significance of this suppression is not known. In this review, we summarize recent studies of mitotic DSB repair and discuss the mechanisms of suppression of DSB repair during mitosis. DSB repair, which maintains genomic integrity in other phases of the cell cycle, is rather toxic to cells during mitosis, often resulting in chromosome missegregation and aberration. Cells have multiple safeguards to prevent genomic instability during mitosis: inhibition of 53BP1 or BRCA1 localization to DSB sites, which is important to promote non-homologous end joining or homologous recombination, respectively, and also modulation of the non-homologous end joining core complex to inhibit DSB repair. We discuss how DSBs during mitosis are toxic and the multiple safeguard systems that suppress genomic instability. © 2014 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association.

  18. The validity of sedimentation data from high molecular weight DNA and the effects of additives on radiation-induced single-strand breakage

    International Nuclear Information System (INIS)

    Dugle, D.L.

    1979-10-01

    The optimization of many of the factors governing reproducible sedimentation behaviour of high molecular weight single-strand DNA in a particular alkaline sucrose density gradient system is described. A range of angular momenta is defined for which a constant strand breakage efficiency is required, despite a rotor speed effect which increases the measured molecular weights at decreasing rotor speeds for larger DNA molecules. The possibility is discussed that the bimodal control DNA profiles obtained after sedimentation at 11 500 rev/min (12 400 g) or less represent structural subunits of the chromatid. The random induction of single-strand DNA breaks by ionizing radiation is demonstrated by the computer-derived fits to the experimental profiles. The enhancement of single-strand break (SSB) yields in hypoxic cells by oxygen, para-nitroacetophenone (PNAP), or any of the three nitrofuran derivatives used was well correlated with increased cell killing. Furthermore, reductions in SSB yields for known hydroxyl radical (OH.) scavengers correlates with the reactivities of these compounds toward OH.. This supports the contention that some type of OH.-induced initial lesion, which may ultimately be expressed as an unrepaired or misrepaired double-strand break, constitutes a lethal event. (author)

  19. The amount of DNA damage needed to activate the radiation-induced G2 checkpoint varies between single cells

    International Nuclear Information System (INIS)

    Tkacz-Stachowska, Kinga; Lund-Andersen, Christin; Velissarou, Angeliki; Myklebust, June H.; Stokke, Trond; Syljuåsen, Randi G.

    2011-01-01

    Background and purpose: The radiation-induced G2 checkpoint helps facilitate DNA repair before cell division. However, recent work has revealed that human cells often escape the G2 checkpoint with unrepaired DNA breaks. The purpose was to explore whether G2 checkpoint activation occurs according to a threshold level of DNA damage. Materials and methods: G2 checkpoint activation was assayed at 75–90 min and 24–48 h after X-ray irradiation of BJ diploid fibroblasts and U2OS osteosarcoma cells. Multiparameter flow cytometry with pacific blue barcoding, and flow cytometry-based sorting of phospho-H3 positive cells to microscope slides, were used to examine the DNA damage marker γ-H2AX in individual mitotic cells that had escaped the G2 checkpoint. Results: For all radiation doses and times tested, the number of γ-H2AX foci varied between individual mitotic cells. At 75 min the median levels of γ-H2AX in mitotic cells increased with higher radiation doses. At 24–48 h, following a prolonged G2 checkpoint, cells were more resistant to checkpoint re-activation by a second dose of radiation. Conclusion: Our results suggest that different amounts of DNA damage are needed to activate the G2 checkpoint in individual cells. Such single cell variation in checkpoint activation may potentially contribute to radiation-induced genomic instability.

  20. Singled out?

    Science.gov (United States)

    Waller, Frank

    2004-03-01

    The increasing use of single use medical devices is being driven by a growing awareness of iatrogenic (from the Greek; caused by the doctor) and nosocomial infections. Public health perceptions relating to transmissible spongiform encephalopathies, specifically variant Creutzfeldt-Jakob disease (vCJD), the Human Immunodeficiency Virus (HIV) and Hepatitis B are high on the political agenda and a matter of concern to healthcare professionals.

  1. Either non-homologous ends joining or homologous recombination is required to repair double-strand breaks in the genome of macrophage-internalized Mycobacterium tuberculosis.

    Science.gov (United States)

    Brzostek, Anna; Szulc, Izabela; Klink, Magdalena; Brzezinska, Marta; Sulowska, Zofia; Dziadek, Jaroslaw

    2014-01-01

    The intracellular pathogen Mycobacterium tuberculosis (Mtb) is constantly exposed to a multitude of hostile conditions and is confronted by a variety of potentially DNA-damaging assaults in vivo, primarily from host-generated antimicrobial toxic radicals. Exposure to reactive nitrogen species and/or reactive oxygen species causes different types of DNA damage, including oxidation, depurination, methylation and deamination, that can result in single- or double-strand breaks (DSBs). These breaks affect the integrity of the whole genome and, when left unrepaired, can lead to cell death. Here, we investigated the role of the DSB repair pathways, homologous recombination (HR) and non-homologous ends joining (NHEJ), in the survival of Mtb inside macrophages. To this end, we constructed Mtb strains defective for HR (ΔrecA), NHEJ [Δ(ku,ligD)], or both DSB repair systems [Δ(ku,ligD,recA)]. Experiments using these strains revealed that either HR or NHEJ is sufficient for the survival and propagation of tubercle bacilli inside macrophages. Inhibition of nitric oxide or superoxide anion production with L-NIL or apocynin, respectively, enabled the Δ(ku,ligD,recA) mutant strain lacking both systems to survive intracellularly. Complementation of the Δ(ku,ligD,recA) mutant with an intact recA or ku-ligD rescued the ability of Mtb to propagate inside macrophages.

  2. Either non-homologous ends joining or homologous recombination is required to repair double-strand breaks in the genome of macrophage-internalized Mycobacterium tuberculosis.

    Directory of Open Access Journals (Sweden)

    Anna Brzostek

    Full Text Available The intracellular pathogen Mycobacterium tuberculosis (Mtb is constantly exposed to a multitude of hostile conditions and is confronted by a variety of potentially DNA-damaging assaults in vivo, primarily from host-generated antimicrobial toxic radicals. Exposure to reactive nitrogen species and/or reactive oxygen species causes different types of DNA damage, including oxidation, depurination, methylation and deamination, that can result in single- or double-strand breaks (DSBs. These breaks affect the integrity of the whole genome and, when left unrepaired, can lead to cell death. Here, we investigated the role of the DSB repair pathways, homologous recombination (HR and non-homologous ends joining (NHEJ, in the survival of Mtb inside macrophages. To this end, we constructed Mtb strains defective for HR (ΔrecA, NHEJ [Δ(ku,ligD], or both DSB repair systems [Δ(ku,ligD,recA]. Experiments using these strains revealed that either HR or NHEJ is sufficient for the survival and propagation of tubercle bacilli inside macrophages. Inhibition of nitric oxide or superoxide anion production with L-NIL or apocynin, respectively, enabled the Δ(ku,ligD,recA mutant strain lacking both systems to survive intracellularly. Complementation of the Δ(ku,ligD,recA mutant with an intact recA or ku-ligD rescued the ability of Mtb to propagate inside macrophages.

  3. Single and double strand breaks induced by 3H incorporated in DNA of cultured human kidney cells

    International Nuclear Information System (INIS)

    Tisljar-Lentulis, G.; Henneberg, P.; Mielke, T.; Feinendegen, L.E.

    1978-01-01

    In the course of the investigations of the biological effects of radionuclides incorporated in DNA single (SSB) and double strand breaks (DSB) caused tritium-decay were measured and compared with respective data resulting from 125 I. Tritium bound to thymidine and iododeoxyuridine seems to be more effective than tritium bound to other DNA-precursors. On the basis of decay, methyl- 3 H thymidine appears to be more effective with regard to the production of strand breaks than 3 H in position 6 of the pyrimidine ring. Based on the numbers of strand-breaks per rad, position 6 is more effective in accordance with data obtained by F. Krasin et al. The ratio of SSBs to DSBs per tritium decay appears to be approximately 8 in mammlian cells. Not only SSBs but also DSBs induced by 3 H in mammalian cells are reapairable. (orig./AJ) [de

  4. Comparison of the effect of radiation exposure from dual-energy CT versus single-energy CT on double-strand breaks at CT pulmonary angiography.

    Science.gov (United States)

    Tao, Shu Min; Li, Xie; Schoepf, U Joseph; Nance, John W; Jacobs, Brian E; Zhou, Chang Sheng; Gu, Hai Feng; Lu, Meng Jie; Lu, Guang Ming; Zhang, Long Jiang

    2018-04-01

    To compare the effect of dual-source dual-energy CT versus single-energy CT on DNA double-strand breaks (DSBs) in blood lymphocytes at CT pulmonary angiography (CTPA). Sixty-two patients underwent either dual-energy CTPA (Group 1: n = 21, 80/Sn140 kVp, 89/38 mAs; Group 2: n = 20, 100/Sn140 kVp, 89/76 mAs) or single-energy CTPA (Group 3: n = 21, 120 kVp, 110 mAs). Blood samples were obtained before and 5 min after CTPA. DSBs were assessed with fluorescence microscopy and Kruskal-Walls tests were used to compare DSBs levels among groups. Volume CT dose index (CTDIvol), dose length product (DLP) and organ radiation dose were compared using ANOVA. There were increased excess DSB foci per lymphocyte 5 min after CTPA examinations in three groups (Group 1: P = .001; Group 2: P = .001; Group 3: P = .006). There were no differences among groups regarding excess DSB foci/cell and percentage of excess DSBs (Group 1, 23%; Group 2, 24%; Group 3, 20%; P = .932). CTDIvol, DLP and organ radiation dose in Group 1 were the lowest among the groups (all P dual-source and single-source CTPA, while dual-source dual-energy CT protocols do not increase the estimated radiation dose and also do not result in a higher incidence of DNA DSBs in patients undergoing CTPA. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Nonhomologous DNA End Joining in Cell-Free Extracts

    Directory of Open Access Journals (Sweden)

    Sheetal Sharma

    2010-01-01

    Full Text Available Among various DNA damages, double-strand breaks (DSBs are considered as most deleterious, as they may lead to chromosomal rearrangements and cancer when unrepaired. Nonhomologous DNA end joining (NHEJ is one of the major DSB repair pathways in higher organisms. A large number of studies on NHEJ are based on in vitro systems using cell-free extracts. In this paper, we summarize the studies on NHEJ performed by various groups in different cell-free repair systems.

  6. AAV Vectorization of DSB-mediated Gene Editing Technologies.

    Science.gov (United States)

    Moser, Rachel J; Hirsch, Matthew L

    2016-01-01

    Recent work both at the bench and the bedside demonstrate zinc-finger nucleases (ZFNs), CRISPR/Cas9, and other programmable site-specific endonuclease technologies are being successfully utilized within and alongside AAV vectors to induce therapeutically relevant levels of directed gene editing within the human chromosome. Studies from past decades acknowledge that AAV vector genomes are enhanced substrates for homology-directed repair in the presence or absence of targeted DNA damage within the host genome. Additionally, AAV vectors are currently the most efficient format for in vivo gene delivery with no vector related complications in >100 clinical trials for diverse diseases. At the same time, advancements in the design of custom-engineered site-specific endonucleases and the utilization of elucidated endonuclease formats have resulted in efficient and facile genetic engineering for basic science and for clinical therapies. AAV vectors and gene editing technologies are an obvious marriage, using AAV for the delivery of repair substrate and/or a gene encoding a designer endonuclease; however, while efficient delivery and enhanced gene targeting by vector genomes are advantageous, other attributes of AAV vectors are less desirable for gene editing technologies. This review summarizes the various roles that AAV vectors play in gene editing technologies and provides insight into its trending applications for the treatment of genetic diseases.

  7. Defense Science Board (DSB) Task Force on Cyber Deterrence

    Science.gov (United States)

    2017-02-01

    Adversary-Specific Campaign Planning and Wargaming Findings: Because deterrence operates by affecting the calculations of specific decision -making...a strategic threat to U.S. critical infrastructure, or to be able to significantly affect the U.S. military’s ability to deploy and operate globally...bolster U.S. cyber deterrence and strengthen U.S. national security. The Task Force notes that the cyber threat to U.S. critical infrastructure is

  8. Defense Science Board (DSB) Summer Study Report on Strategic Surprise

    Science.gov (United States)

    2015-07-01

    modeling  and  simulation capabilities and test facilities.  Recommendation 15  Leveraging the Internet of Things  Department of Defense should create a...Manferdelli      Intel  Dr. Joseph  Markowitz       Private Consultant  Dr. Mark Maybury      MITRE  Hon. James Miller      Private Consultant  Hon. Judith

  9. Design of a hybrid double-sideband/single-sideband (schlieren) objective aperture suitable for electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Buijsse, Bart; Laarhoven, Frank M.H.M. van [FEI Company, PO Box 80066, 5600 KA Eindhoven (Netherlands); Schmid, Andreas K.; Cambie, Rossana; Cabrini, Stefano; Jin, Jian [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Glaeser, Robert M., E-mail: rmglaeser@lbl.gov [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)

    2011-12-15

    A novel design is described for an aperture that blocks a half-plane of the electron diffraction pattern out to a desired scattering angle, and then - except for a narrow support beam - transmits all of the scattered electrons beyond that angle. Our proposed tulip-shaped design is thus a hybrid between the single-sideband (ssb) aperture, which blocks a full half-plane of the diffraction pattern, and the conventional (i.e. fully open) double-sideband (dsb) aperture. The benefits of this hybrid design include the fact that such an aperture allows one to obtain high-contrast images of weak-phase objects with the objective lens set to Scherzer defocus. We further demonstrate that such apertures can be fabricated from thin-foil materials by milling with a focused ion beam (FIB), and that such apertures are fully compatible with the requirements of imaging out to a resolution of at least 0.34 nm. As is known from earlier work with single-sideband apertures, however, the edge of such an aperture can introduce unwanted, electrostatic phase shifts due to charging. The principal requirement for using such an aperture in a routine data-collection mode is thus to discover appropriate materials, protocols for fabrication and processing and conditions of use such that the hybrid aperture remains free of charging over long periods of time. -- Highlights: Black-Right-Pointing-Pointer New objective-aperture design is proposed for imaging weak-phase objects. Black-Right-Pointing-Pointer Design produces single-sideband contrast at low spatial frequencies. Black-Right-Pointing-Pointer Design also retains Scherzer-defocus phase contrast at higher resolution. Black-Right-Pointing-Pointer Proof-of-concept results are presented for microfabricated apertures. Black-Right-Pointing-Pointer Charging of such apertures during use remains an experimental challenge.

  10. Single Audit: Single Audit Act Effectiveness Issues

    National Research Council Canada - National Science Library

    Thompson, Sally

    2002-01-01

    As discussed in the report we are releasing today, our work to review agency actions to ensure that recipients take timely and appropriate corrective actions to fix audit findings contained in single...

  11. Single-Sex Classrooms

    Science.gov (United States)

    Protheroe, Nancy

    2009-01-01

    Although single-sex education was once the norm in the U.S., the practice has largely been confined to private schools for more than a century. However, with the introduction of the final version of the U.S. Department of Education's so-called single-sex regulations in 2006, public schools were allowed greater flexibility to offer single-sex…

  12. Superconducting Single Photon Detectors

    NARCIS (Netherlands)

    Dorenbos, S.N.

    2011-01-01

    This thesis is about the development of a detector for single photons, particles of light. New techniques are being developed that require high performance single photon detection, such as quantum cryptography, single molecule detection, optical radar, ballistic imaging, circuit testing and

  13. Single frequency intracavity SRO

    DEFF Research Database (Denmark)

    Abitan, Haim; Buchhave, Preben

    2000-01-01

    Summary form only given. A single resonance optical parametric oscillator (SRO) is inserted intracavity to a CW high power, single frequency, and ring Nd:YVO4 laser. We obtain a stable single frequency CW SRO with output at 1.7-1.9 μm (idler) and a resonating signal at 2.3-2.6 μm. The behavior...

  14. Single atom oscillations

    International Nuclear Information System (INIS)

    Wiorkowski, P.; Walther, H.

    1990-01-01

    Modern methods of laser spectroscopy allow the study of single atoms or ions in an unperturbed environment. This has opened up interesting new experiments, among them the detailed study of radiation-atom coupling. In this paper, the following two experiments dealing with this problem are reviewed: the single-atom maser and the study of the resonance fluorescence of a single stored ion. The simplest and most fundamental system for studying radiation-matter coupling is a single two-level atom interacting with a single mode of an electromagnetic field in a cavity. This problem received a great deal of attention shortly after the maser was invented

  15. Single-Phase PLLs

    DEFF Research Database (Denmark)

    Golestan, Saeed; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

    2017-01-01

    Single-phase phase-locked loops (PLLs) are popular for the synchronization and control of single-phase gridconnected converters. They are also widely used for monitoring and diagnostic purposes in the power and energy areas. In recent years, a large number of single-phase PLLs with different stru......-PLLs). The members of each category are then described and their pros and cons are discussed. This work provides a deep insight into characteristics of different single-phase PLLs and, therefore, can be considered as a reference for researchers and engineers....

  16. Single ventricle cardiac defect

    International Nuclear Information System (INIS)

    Eren, B.; Turkmen, N.; Fedakar, R.; Cetin, V.

    2010-01-01

    Single ventricle heart is defined as a rare cardiac abnormality with a single ventricle chamber involving diverse functional and physiological defects. Our case is of a ten month-old baby boy who died shortly after admission to the hospital due to vomiting and diarrhoea. Autopsy findings revealed cyanosis of finger nails and ears. Internal examination revealed; large heart, weighing 60 grams, single ventricle, without a septum and upper membranous part. Single ventricle is a rare pathology, hence, this paper aims to discuss this case from a medico-legal point of view. (author)

  17. Single photon emission tomography

    International Nuclear Information System (INIS)

    Buvat, Irene

    2011-09-01

    The objective of this lecture is to present the single photon emission computed tomography (SPECT) imaging technique. Content: 1 - Introduction: anatomic, functional and molecular imaging; Principle and role of functional or molecular imaging; 2 - Radiotracers: chemical and physical constraints, main emitters, radioisotopes production, emitters type and imaging techniques; 3 - Single photon emission computed tomography: gamma cameras and their components, gamma camera specifications, planar single photon imaging characteristics, gamma camera and tomography; 4 - Quantification in single photon emission tomography: attenuation, scattering, un-stationary spatial resolution, partial volume effect, movements, others; 5 - Synthesis and conclusion

  18. A restricted test of single word intelligibility in 3-year-old children with and without cleft palate

    DEFF Research Database (Denmark)

    Willadsen, Elisabeth; Poulsen, Mads

    2012-01-01

    Abstract Objective: In a previous study, children with cleft palate with hard palate closure at 12 months of age showed more typical phonological development than children with an unrepaired hard palate at 36 months of age. This finding was based on narrow transcription of word initial target...... hard palate closure at either12 months (HPR (hard palate repaired)) or 36 months (HPU (hard palate unrepaired)), were compared to data obtained from 14 age-matched, typically developing, control children. Methods: Video recordings of the children naming target words were shown to 84 naïve listeners...... consonants obtained from a simple naming test. To evaluate the relevance of this finding, we investigated how well the children's target words were understood by 84 naïve listeners. Design: A cross-sectional study. Participants: Data obtained from twenty-eight children with UCLP, 3 years of age, who received...

  19. Sensing single electrons with single molecules

    International Nuclear Information System (INIS)

    Plakhotnik, Taras

    2007-01-01

    We propose a new methodology for probing transport of just one electron, a process of great importance both in nature and in artificial devices. Our idea for locating a single electron is analogues to the conventional GPS where signals from several satellites are used to locate a macro object. Using fluorescent molecules as tiny sensors, it is possible to determine 3D displacement vector of an electron

  20. Single-strand DNA binding protein SSB1 facilitates TERT recruitment to telomeres and maintains telomere G-overhangs

    Science.gov (United States)

    Pandita, Raj K.; Chow, Tracy T.; Udayakumar, Durga; Bain, Amanda L.; Cubeddu, Liza; Hunt, Clayton R.; Shi, Wei; Horikoshi, Nobuo; Zhao, Yong; Wright, Woodring E.; Khanna, Kum Kum; Shay, Jerry W.; Pandita, Tej K.

    2015-01-01

    Proliferating mammalian stem and cancer cells express telomerase (TERT) in an effort to extend chromosomal G-overhangs and maintain telomere ends. Telomerase-expressing cells also have higher levels of the single-stranded DNA binding protein SSB1, which has a critical role in DNA double-strand break repair. Here we report that SSB1 binds specifically to G-strand telomeric DNA in vitro and associates with telomeres in vivo. SSB1 interacted with the TERT catalytic subunit and regulates its interaction with telomeres. Deletion of SSB1 reduced TERT interaction with telomeres and lead to G-overhang loss. While SSB1 was recruited to DSB sites, we found no corresponding change in TERT levels at these sites, implying that SSB1-TERT interaction relied upon a specific chromatin structure or context. Our findings offer an explanation for how telomerase is recruited to telomeres to facilitate G-strand DNA extension, a critical step in maintaining telomere ends and cell viability in all cancer cells. PMID:25589350

  1. Immediate and repair induced DNA double strand breaks in mammalian cells

    International Nuclear Information System (INIS)

    Bryant, P.E.

    1986-01-01

    It seems logical to postulate that double strand breaks (dsb) arising both at the time of irradiation and via repair processes are potentially equally damaging for a cell in terms of the potential to induce chromosomal aberrations. However, in some cell systems the repair of double es or es-ssb sites may run concurrently with the incision so that these lesions do not remain open for long: hence the lack of accumulation of dsb during repair. The rate of incision will thus determine both the accumulation and the probability of exchanges leading to chromosomal aberrations between these and other frank dsb. Rapid incision leading to a large additional pool of dsb appears to be the case in Chinese hamster V79 cells. Some evidence also exists for the conversion of base damage, via dsb, into deletion type chromatid aberrations which accumulate in irradiated G2 human cells treated with ara C. A small fraction of dsb, probably arising both at the time of irradiation as well as enzymatically during repair of base or sugar damage, appears to be either left unrepaired, yielding deletion type chromosomal aberrations, or is misrepaired, yielding exchange aberrations. The induction of these aberrations appears to be of central importance in the biological effects of ionizing radiation such as mutations, oncogenic transformation, and cell death. 52 refs., 5 figs

  2. Single-sided NMR

    CERN Document Server

    Casanova, Federico; Blümich, Bernhard

    2011-01-01

    Single-Sided NMR describes the design of the first functioning single-sided tomograph, the related measurement methods, and a number of applications. One of the key advantages to this method is the speed at which the images are obtained.

  3. Understanding Single Adulthood.

    Science.gov (United States)

    Stein, Peter J.

    The life styles and life chances of the unmarried include elements of choices. Singles may be grouped and characterized according to whether their status may be considered stable or temporary. A life cycle, or continuum model of singlehood is reviewed, including its different factors, or phases. A new model for singles is proposed--a life spiral…

  4. Single gaze gestures

    DEFF Research Database (Denmark)

    Møllenbach, Emilie; Lilholm, Martin; Gail, Alastair

    2010-01-01

    This paper examines gaze gestures and their applicability as a generic selection method for gaze-only controlled interfaces. The method explored here is the Single Gaze Gesture (SGG), i.e. gestures consisting of a single point-to-point eye movement. Horizontal and vertical, long and short SGGs were...

  5. Single molecules and nanotechnology

    CERN Document Server

    Vogel, Horst

    2007-01-01

    This book focuses on recent advances in the rapidly evolving field of single molecule research. These advances are of importance for the investigation of biopolymers and cellular biochemical reactions, and are essential to the development of quantitative biology. Written by leading experts in the field, the articles cover a broad range of topics, including: quantum photonics of organic dyes and inorganic nanoparticles their use in detecting properties of single molecules the monitoring of single molecule (enzymatic) reactions single protein (un)folding in nanometer-sized confined volumes the dynamics of molecular interactions in biological cells The book is written for advanced students and scientists who wish to survey the concepts, techniques and results of single molecule research and assess them for their own scientific activities.

  6. Single-photon imaging

    CERN Document Server

    Seitz, Peter

    2011-01-01

    The acquisition and interpretation of images is a central capability in almost all scientific and technological domains. In particular, the acquisition of electromagnetic radiation, in the form of visible light, UV, infrared, X-ray, etc. is of enormous practical importance. The ultimate sensitivity in electronic imaging is the detection of individual photons. With this book, the first comprehensive review of all aspects of single-photon electronic imaging has been created. Topics include theoretical basics, semiconductor fabrication, single-photon detection principles, imager design and applications of different spectral domains. Today, the solid-state fabrication capabilities for several types of image sensors has advanced to a point, where uncoooled single-photon electronic imaging will soon become a consumer product. This book is giving a specialist´s view from different domains to the forthcoming “single-photon imaging” revolution. The various aspects of single-photon imaging are treated by internati...

  7. Single Nanoparticle Plasmonic Sensors

    Directory of Open Access Journals (Sweden)

    Manish Sriram

    2015-10-01

    Full Text Available The adoption of plasmonic nanomaterials in optical sensors, coupled with the advances in detection techniques, has opened the way for biosensing with single plasmonic particles. Single nanoparticle sensors offer the potential to analyse biochemical interactions at a single-molecule level, thereby allowing us to capture even more information than ensemble measurements. We introduce the concepts behind single nanoparticle sensing and how the localised surface plasmon resonances of these nanoparticles are dependent upon their materials, shape and size. Then we outline the different synthetic approaches, like citrate reduction, seed-mediated and seedless growth, that enable the synthesis of gold and silver nanospheres, nanorods, nanostars, nanoprisms and other nanostructures with tunable sizes. Further, we go into the aspects related to purification and functionalisation of nanoparticles, prior to the fabrication of sensing surfaces. Finally, the recent developments in single nanoparticle detection, spectroscopy and sensing applications are discussed.

  8. Single Policy Study

    DEFF Research Database (Denmark)

    Kronsell, Annica; Manners, Ian James

    2015-01-01

    Single policy studies are the most common form of European Union (EU) research. Single policy studies are widely used to understand the role of the EU in a wide variety of sectors, together with their development over time, and often offer public policy prescriptions. This chapter discusses...... the relevance of single policy studies in EU research and give examples of how such research can be designed and carried out. The chapter reviews three examples of single policy studies using different methods based on EU environmental policy, the EU biofuels directive, and the EU Common Security and Defence...... Policy (CSDP). The examples are illustrative of how single policy studies can be designed to use different approaches in the analysis: multiple streams approach to policy-making; a comparative hypothesis testing; and feminist institutional theory....

  9. Single-Arc IMRT?

    International Nuclear Information System (INIS)

    Bortfeld, Thomas; Webb, Steve

    2009-01-01

    The idea of delivering intensity-modulated radiation therapy (IMRT) with a multileaf collimator in a continuous dynamic mode during a single rotation of the gantry has recently gained momentum both in research and industry. In this note we investigate the potential of this Single-Arc IMRT technique at a conceptual level. We consider the original theoretical example case from Brahme et al that got the field of IMRT started. Using analytical methods, we derive deliverable intensity 'landscapes' for Single-Arc as well as standard IMRT and Tomotherapy. We find that Tomotherapy provides the greatest flexibility in shaping intensity landscapes and that it allows one to deliver IMRT in a way that comes close to the ideal case in the transverse plane. Single-Arc and standard IMRT make compromises in different areas. Only in relatively simple cases that do not require substantial intensity modulation will Single-Arc be dosimetrically comparable to Tomotherapy. Compared with standard IMRT, Single-Arc could be dosimetrically superior in certain cases if one is willing to accept the spreading of low dose values over large volumes of normal tissue. In terms of treatment planning, Single-Arc poses a more challenging optimization problem than Tomotherapy or standard IMRT. We conclude that Single-Arc holds potential as an efficient IMRT technique especially for relatively simple cases. In very complex cases, Single-Arc may unduly compromise the quality of the dose distribution, if one tries to keep the treatment time below 2 min or so. As with all IMRT techniques, it is important to explore the tradeoff between plan quality and the efficiency of its delivery carefully for each individual case. (note)

  10. Single neuron computation

    CERN Document Server

    McKenna, Thomas M; Zornetzer, Steven F

    1992-01-01

    This book contains twenty-two original contributions that provide a comprehensive overview of computational approaches to understanding a single neuron structure. The focus on cellular-level processes is twofold. From a computational neuroscience perspective, a thorough understanding of the information processing performed by single neurons leads to an understanding of circuit- and systems-level activity. From the standpoint of artificial neural networks (ANNs), a single real neuron is as complex an operational unit as an entire ANN, and formalizing the complex computations performed by real n

  11. Single photon ECT

    International Nuclear Information System (INIS)

    Maeda, Toshio; Matsuda, Hiroshi; Tada, Akira; Bunko, Hisashi; Koizumi, Kiyoshi

    1982-01-01

    The detectability of lesions located deep in a body or overlapped with a physiologically increased activity improve with the help of single photon ECT. In some cases, the ECT is superior to the conventional gamma camera images and X-ray CT scans in the evaluation of the location and size of lesion. The single photon ECT of the brain compares favorably with the contrast enhansed X-ray CT scans. The most important adaptation of the single photon ECT are the detection of recurrent brain tumors after craniotomy and the evaluation of ischemic heart diseases. (author)

  12. Single Electron Tunneling

    International Nuclear Information System (INIS)

    Ruggiero, Steven T.

    2005-01-01

    Financial support for this project has led to advances in the science of single-electron phenomena. Our group reported the first observation of the so-called ''Coulomb Staircase'', which was produced by tunneling into ultra-small metal particles. This work showed well-defined tunneling voltage steps of width e/C and height e/RC, demonstrating tunneling quantized on the single-electron level. This work was published in a now well-cited Physical Review Letter. Single-electron physics is now a major sub-field of condensed-matter physics, and fundamental work in the area continues to be conducted by tunneling in ultra-small metal particles. In addition, there are now single-electron transistors that add a controlling gate to modulate the charge on ultra-small photolithographically defined capacitive elements. Single-electron transistors are now at the heart of at least one experimental quantum-computer element, and single-electron transistor pumps may soon be used to define fundamental quantities such as the farad (capacitance) and the ampere (current). Novel computer technology based on single-electron quantum dots is also being developed. In related work, our group played the leading role in the explanation of experimental results observed during the initial phases of tunneling experiments with the high-temperature superconductors. When so-called ''multiple-gap'' tunneling was reported, the phenomenon was correctly identified by our group as single-electron tunneling in small grains in the material. The main focus throughout this project has been to explore single electron phenomena both in traditional tunneling formats of the type metal/insulator/particles/insulator/metal and using scanning tunneling microscopy to probe few-particle systems. This has been done under varying conditions of temperature, applied magnetic field, and with different materials systems. These have included metals, semi-metals, and superconductors. Amongst a number of results, we have

  13. Coalescence of DNA Double Strand Breaks Induced by Galactic Cosmic Radiation is Modulated by Genetics in 15 Inbred Strains of Mice

    Science.gov (United States)

    Penninckx, Sebastien; Ray, Shayoni; Staatz, Kevin; Degorre, Charlotte; Guiet, Elodie; Viger, Louise; Snijders, Antoine M.; Mao, Jian-Hua; Karpen, Gary; Costes, Sylvain V.

    2018-01-01

    In this manuscript we address the challenges associated with the ability to predict radiation sensitivity associated with exposure to either cosmic radiation or X-rays in a population study, by monitoring DNA damage sensing protein 53BP1 forming small nuclear radiation-induced foci (RIF) as a surrogate biomarker of DNA double strand breaks (DSB). 76 primary skin fibroblasts were isolated from 10 collaborative cross strains and five reference inbred mice (C57Bl/6, BALB/CByJ, B6C3, C3H and CBA/CaJ) and exposed to three different charged nuclei of increasing LET (350 MeV/n Si, 350 MeV/n Ar and 600 MeV/n Fe) and X-ray. Our data brings strong evidence against the classic "contact-first" model where DSBs are assumed to be immobile and repaired at the lesion site. In contrast, our model suggests nearby DSBs move into single repair unit characterized by large RIF before the repair machinery kicks in. Such model has the advantage of being much more efficient molecularly but is poorly suited to deal with cosmic radiation, where energy is concentrated along the particle trajectory, inducing a large density of DSBs along each particle track. In accordance with this model, RIF quantification after X-ray exposition showed a saturated dose response for early time points post-irradiation for all strains. Similarly, the high-LET response showed that RIF number matched the number of track per cell, not the number of expected DSB per cell (1). At the temporal level, we noted that the percentage of unrepaired high-LET tracks over a 48 hour time-course increased with LET, confirming that the DNA repair process becomes more difficult as more DSB coalesce into single RIF. There was also good agreement between persistent RIF levels measured in-vitro in the primary skin cultures and survival levels of T-cells and B-cells collected in blood samples from 10 CC strains 24 hours after 0.1 Gy whole-body dose of X-ray. This suggests that persistent RIF 24 hour post-IR is a good surrogate in

  14. A Single Atom Antenna

    International Nuclear Information System (INIS)

    Trinter, Florian; Williams, Joshua B; Weller, Miriam; Waitz, Markus; Pitzer, Martin; Voigtsberger, Jörg; Schober, Carl; Kastirke, Gregor; Müller, Christian; Goihl, Christoph; Burzynski, Phillip; Wiegandt, Florian; Wallauer, Robert; Kalinin, Anton; Schmidt, Lothar Ph H; Schöffler, Markus S; Jahnke, Till; Dörner, Reinhard; Chiang, Ying-Chih; Gokhberg, Kirill

    2015-01-01

    Here we demonstrate the smallest possible implementation of an antenna-receiver complex which consists of a single (helium) atom acting as the antenna and a second (neon) atom acting as a receiver. (paper)

  15. Single Beam Holography.

    Science.gov (United States)

    Chen, Hsuan; Ruterbusch, Paul H.

    1979-01-01

    Discusses how holography can be used as part of undergraduate physics laboratories. The authors propose a single beam technique of holography, which will reduce the recording scheme as well as relax the isolation requirements. (HM)

  16. Single-photon sources

    International Nuclear Information System (INIS)

    Lounis, Brahim; Orrit, Michel

    2005-01-01

    The concept of the photon, central to Einstein's explanation of the photoelectric effect, is exactly 100 years old. Yet, while photons have been detected individually for more than 50 years, devices producing individual photons on demand have only appeared in the last few years. New concepts for single-photon sources, or 'photon guns', have originated from recent progress in the optical detection, characterization and manipulation of single quantum objects. Single emitters usually deliver photons one at a time. This so-called antibunching of emitted photons can arise from various mechanisms, but ensures that the probability of obtaining two or more photons at the same time remains negligible. We briefly recall basic concepts in quantum optics and discuss potential applications of single-photon states to optical processing of quantum information: cryptography, computing and communication. A photon gun's properties are significantly improved by coupling it to a resonant cavity mode, either in the Purcell or strong-coupling regimes. We briefly recall early production of single photons with atomic beams, and the operation principles of macroscopic parametric sources, which are used in an overwhelming majority of quantum-optical experiments. We then review the photophysical and spectroscopic properties and compare the advantages and weaknesses of various single nanometre-scale objects used as single-photon sources: atoms or ions in the gas phase and, in condensed matter, organic molecules, defect centres, semiconductor nanocrystals and heterostructures. As new generations of sources are developed, coupling to cavities and nano-fabrication techniques lead to improved characteristics, delivery rates and spectral ranges. Judging from the brisk pace of recent progress, we expect single photons to soon proceed from demonstrations to applications and to bring with them the first practical uses of quantum information

  17. Single particle dynamics

    International Nuclear Information System (INIS)

    Siemens, P.J.; Jensen, A.S.

    1985-01-01

    It is shown that the opening of the 3-quasiparticle continuum at 3Δ sets the energy scale for the enhancement of the effective mass near the Fermi surface of nuclei. The authors argue that the spreading width of single-particle states due to coupling with low-lying collective modes is qualitatively different from the two-body collision mechanism, and contributes little to the single-particle lifetime in the sense of the optical model. (orig.)

  18. Performance enhanced DDO-OFDM system with adaptively partitioned precoding and single sideband modulation.

    Science.gov (United States)

    Chen, Xi; Feng, Zhenhua; Tang, Ming; Fu, Songnian; Liu, Deming

    2017-09-18

    As a promising solution for short-to-medium transmission systems, direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) or discrete multi-tone (DMT) has been intensively investigated in last decade. Benefitting from the advantages of peak-to-average power (PAPR) reduction and signal-to-noise ratio (SNR) equalization, precoding techniques are widely applied to enhance the performance of DDO-OFDM systems. However, the conventional method of partitioning precoding sets limits the ability of precoding schemes to optimize the SNR variation and the allocation of modulation formats. Thus, the precoding transmission systems are hard to reach the capacity that traditional bit-power loading (BPL) techniques, like the Levin-Campello (LC) algorithm, can achieve. In this paper, we investigate the principle of SNR variation for precoded DDO-OFDM systems and theoretically demonstrate that the SNR equalization effect of precoding techniques is actually determined by the noise equalization process. Based on this fact, we propose an adaptively partitioned precoding (APP) algorithm to unlock the ability to control the SNR of each subcarrier. As demonstrated by the simulation and experimental results, the proposed APP algorithm achieves the transmission capacity as high as the LC algorithm and has nearly 1 dB PAPR reduction. Besides, the look-up table (LUT) operation ensures low complexity of the proposed APP algorithm compared with LC algorithm. To avoid severe chromatic dispersion (CD) induced spectral fading, single sideband (SSB) modulation is also implemented. We find that SSB modulation can reach the capacity of double sideband (DSB) modulation in optical back-to-back (OB2B) configuration by optimizing the modulation index. Therefore, the APP based SSB-DDO-OFDM scheme can sufficiently enhance the performance of cost-sensitive short-to-medium reach optical fiber communication systems.

  19. Unrepaired Tetralogy of Fallot with Absent Pulmonary Valve in a Mildly Symptomatic 16-Year-Old Boy.

    Science.gov (United States)

    Drogalis-Kim, Diana E; Reemtsen, Brian L; Reardon, Leigh Christopher

    2016-12-01

    Absent pulmonary valve is a rare and severe variant seen in only 3% to 6% of patients with tetralogy of Fallot. Fetuses with this combined condition who survive through birth typically need intervention in infancy or early childhood because of respiratory distress, heart failure, or failure to thrive. We describe the unusual case of a mildly symptomatic 16-year-old boy with these conditions who underwent successful primary repair. Our search of the medical literature yielded fewer than 5 cases of tetralogy of Fallot with absent pulmonary valve (or variants with an absent left pulmonary artery) and survival without repair into later adolescence or adulthood.

  20. Perioperative Management of Subarachnoid Hemorrhage in a Patient with Alagille Syndrome and Unrepaired Tetralogy of Fallot: Case Report

    Directory of Open Access Journals (Sweden)

    Juan Fiorda-Diaz

    2017-12-01

    Full Text Available Alagille syndrome (ALGS is a genetic disorder associated with multisystem dysfunction involving the hepatic, cardiovascular, and neurologic systems. Tetralogy of Fallot (TOF, a congenital cardiac anomaly, is commonly found in these patients. Patients with ALGS may also have an increased risk of cerebrovascular abnormalities and bleeding. Ruptured cerebral aneurysm and subarachnoid hemorrhage (SAH may be developed, increasing the incidence of morbidity and mortality. Advances in neuroimaging and neurosurgery have allowed early identification and treatment of such vascular abnormalities, improving patients’ outcomes and reducing life-threatening complications such as intracranial bleeding. Authors describe the perioperative management of a patient with ALGS and TOF who was admitted to the emergency department due a ruptured intracranial aneurysm with concomitant SAH. Surgical treatment included diagnostic cerebral arteriography with coil embolization of a left posterior communicating artery aneurysm, and placement of right external ventricular drain (EVD. The combination of neuroprotective anesthetic techniques, fast emergence from anesthesia, and maintenance of intraoperative hemodynamic stability led to a successful perioperative management. A multidisciplinary approach in specialized centers is essential for the treatment of patients with SAH, especially in patients with ALGS and complex congenital heart disease such as TOF.

  1. Single-Mode VCSELs

    Science.gov (United States)

    Larsson, Anders; Gustavsson, Johan S.

    The only active transverse mode in a truly single-mode VCSEL is the fundamental mode with a near Gaussian field distribution. A single-mode VCSEL produces a light beam of higher spectral purity, higher degree of coherence and lower divergence than a multimode VCSEL and the beam can be more precisely shaped and focused to a smaller spot. Such beam properties are required in many applications. In this chapter, after discussing applications of single-mode VCSELs, we introduce the basics of fields and modes in VCSELs and review designs implemented for single-mode emission from VCSELs in different materials and at different wavelengths. This includes VCSELs that are inherently single-mode as well as inherently multimode VCSELs where higher-order modes are suppressed by mode selective gain or loss. In each case we present the current state-of-the-art and discuss pros and cons. At the end, a specific example with experimental results is provided and, as a summary, the most promising designs based on current technologies are identified.

  2. Single-photon imaging

    International Nuclear Information System (INIS)

    Seitz, Peter; Theuwissen, Albert J.P.

    2011-01-01

    The acquisition and interpretation of images is a central capability in almost all scientific and technological domains. In particular, the acquisition of electromagnetic radiation, in the form of visible light, UV, infrared, X-ray, etc. is of enormous practical importance. The ultimate sensitivity in electronic imaging is the detection of individual photons. With this book, the first comprehensive review of all aspects of single-photon electronic imaging has been created. Topics include theoretical basics, semiconductor fabrication, single-photon detection principles, imager design and applications of different spectral domains. Today, the solid-state fabrication capabilities for several types of image sensors has advanced to a point, where uncooled single-photon electronic imaging will soon become a consumer product. This book is giving a specialist's view from different domains to the forthcoming ''single-photon imaging'' revolution. The various aspects of single-photon imaging are treated by internationally renowned, leading scientists and technologists who have all pioneered their respective fields. (orig.)

  3. Single port laparoscopic surgery

    DEFF Research Database (Denmark)

    Springborg, Henrik; Istre, Olav

    2012-01-01

    LESS, or laparo-endoscopic single site surgery, is a promising new method in minimally invasive surgery. An increasing number of surgical procedures are being performed using this technique, however, its large-scale adoption awaits results of prospective randomized controlled studies confirming...... potential benefits. Theoretically, cosmetic outcomes, postoperative pain and complication rates could be improved with use of single site surgery. This study describes introduction of the method in a private hospital in Denmark, in which 40 patients have been treated for benign gynecologic conditions....... Although the operations described are the first of their kind reported in Denmark, favorable operating times and very low complication rates are seen. It is the authors' opinion that in addition to being feasible for hysterectomy, single port laparoscopy may become the preferred method for many simple...

  4. Single Cell Oncogenesis

    Science.gov (United States)

    Lu, Xin

    It is believed that cancer originates from a single cell that has gone through generations of evolution of genetic and epigenetic changes that associate with the hallmarks of cancer. In some cancers such as various types of leukemia, cancer is clonal. Yet in other cancers like glioblastoma (GBM), there is tremendous tumor heterogeneity that is likely to be caused by simultaneous evolution of multiple subclones within the same tissue. It is obvious that understanding how a single cell develops into a clonal tumor upon genetic alterations, at molecular and cellular levels, holds the key to the real appreciation of tumor etiology and ultimate solution for therapeutics. Surprisingly very little is known about the process of spontaneous tumorigenesis from single cells in human or vertebrate animal models. The main reason is the lack of technology to track the natural process of single cell changes from a homeostatic state to a progressively cancerous state. Recently, we developed a patented compound, photoactivatable (''caged'') tamoxifen analogue 4-OHC and associated technique called optochemogenetic switch (OCG switch), which we believe opens the opportunity to address this urgent biological as well as clinical question about cancer. We propose to combine OCG switch with genetically engineered mouse models of head and neck squamous cell carcinoma and high grade astrocytoma (including GBM) to study how single cells, when transformed through acute loss of tumor suppressor genes PTEN and TP53 and gain of oncogenic KRAS, can develop into tumor colonies with cellular and molecular heterogeneity in these tissues. The abstract is for my invited talk in session ``Beyond Darwin: Evolution in Single Cells'' 3/18/2016 11:15 AM.

  5. Single well techniques

    International Nuclear Information System (INIS)

    Drost, W.

    1983-01-01

    The single well technique method includes measurement of parameters of groundwater flow in saturated rock. For determination of filtration velocity the dilution of radioactive tracer is measured, for direction logging the collimeter is rotated in the probe linked with the compass. The limiting factor for measurement of high filtration velocities is the occurrence of turbulent flow. The single well technique is used in civil engineering projects, water works and subsurface drainage of liquid waste from disposal sites. The radioactive tracer method for logging the vertical fluid movement in bore-holes is broadly used in groundwater survey and exploitation. (author)

  6. Beware the single hit!

    CERN Multimedia

    2008-01-01

    The first time that single particle effects from cosmic rays on electronics were observed was in 1991, when one of the instruments aboard an ESA satellite broke down after only five days in space. On 5 July, the TS-LEA group will have completed the installation of monitors that will help to reduce similar dangerous effects on LHC electronics.

  7. Single bubble sonoluminescence

    NARCIS (Netherlands)

    Brenner, Michael P.; Hilgenfeldt, Sascha; Lohse, Detlef

    2002-01-01

    Single-bubble sonoluminescence occurs when an acoustically trapped and periodically driven gas bubble collapses so strongly that the energy focusing at collapse leads to light emission. Detailed experiments have demonstrated the unique properties of this system: the spectrum of the emitted light

  8. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 2. Single-Molecule Spectroscopy: Every Molecule is Different! Kankan Bhattacharyya. General Article Volume 20 Issue 2 February 2015 pp 151-164. Fulltext. Click here to view fulltext PDF. Permanent link:

  9. Single cell metabolomics

    NARCIS (Netherlands)

    Heinemann, Matthias; Zenobi, Renato

    Recent discoveries suggest that cells of a clonal population often display multiple metabolic phenotypes at the same time. Motivated by the success of mass spectrometry (MS) in the investigation of population-level metabolomics, the analytical community has initiated efforts towards MS-based single

  10. Beyond the Single Story

    Science.gov (United States)

    McKenney, Yekaterina

    2016-01-01

    Teachers of world literature have the opportunity to help students explore the more complex reality behind the stereotypes that they often see in the media. If we don't encourage students to challenge one-dimensional "single stories" that characterize an entire people--whether Muslims, Russians, Mexicans, African Americans, Chinese,…

  11. Single Value Devices

    NARCIS (Netherlands)

    Mader, Angelika H.; Dertien, Edwin Christian; Reidsma, Dennis

    2011-01-01

    We live in a world of continuous information overflow, but the quality of information and communication is suffering. Single value devices contribute to the information and communication quality by fo- cussing on one explicit, relevant piece of information. The information is decoupled from a

  12. A model system for DNA repair studies

    International Nuclear Information System (INIS)

    Lange, C.S.; Perlmutter, E.

    1984-01-01

    The search for the ''lethal lesion:'' which would yield a molecular explanation of biological survival curves led to attempts to correlate unrepaired DNA lesions with loss of reproductive integrity. Such studies have shown the crucial importance of DNA repair systems. The unrepaired DSB has been sought for such correlation, but in such study the DNA was too large, polydisperse, and/or structurally complex to permit precise measurement of break induction and repair. Therefore, an analog of higher order systems but with a genome of readily measurable size, is needed. Bacteriophage T4 is such an analog. Both its biological (PFU) and molecular (DNA) survival curves are exponentials. Its aerobic /sub PFU/D/sub 37///sub DNA/D/sub 37/ ratio, (410 +- 4.5Gy/540 +- 25 Gy) indicates that 76 +- 4% of lethality at low multiplicity infection (moi 1) the survival is greater than can be explained if the assumption of no parental DSB repair were valid. Both T4 and its host have DSB repair systems which can be studied by the infectious center method. Results of such studies are discussed

  13. Single frequency semiconductor lasers

    CERN Document Server

    Fang, Zujie; Chen, Gaoting; Qu, Ronghui

    2017-01-01

    This book systematically introduces the single frequency semiconductor laser, which is widely used in many vital advanced technologies, such as the laser cooling of atoms and atomic clock, high-precision measurements and spectroscopy, coherent optical communications, and advanced optical sensors. It presents both the fundamentals and characteristics of semiconductor lasers, including basic F-P structure and monolithic integrated structures; interprets laser noises and their measurements; and explains mechanisms and technologies relating to the main aspects of single frequency lasers, including external cavity lasers, frequency stabilization technologies, frequency sweeping, optical phase locked loops, and so on. It paints a clear, physical picture of related technologies and reviews new developments in the field as well. It will be a useful reference to graduate students, researchers, and engineers in the field.

  14. Single Nucleotide Polymorphism

    DEFF Research Database (Denmark)

    Børsting, Claus; Pereira, Vania; Andersen, Jeppe Dyrberg

    2014-01-01

    Single nucleotide polymorphisms (SNPs) are the most frequent DNA sequence variations in the genome. They have been studied extensively in the last decade with various purposes in mind. In this chapter, we will discuss the advantages and disadvantages of using SNPs for human identification...... of SNPs. This will allow acquisition of more information from the sample materials and open up for new possibilities as well as new challenges....

  15. Single sector supersymmetry breaking

    International Nuclear Information System (INIS)

    Luty, Markus A.; Terning, John

    1999-01-01

    We review recent work on realistic models that break supersymmetry dynamically and give rise to composite quarks and leptons, all in a single sector. These models have a completely natural suppression of flavor-changing neutral currents, and the hierarchy of Yukawa couplings is explained by the dimensionality of composite states. The generic signatures are unification of scalar masses with different quantum numbers at the compositeness scale, and lighter gaugino, Higgsino, and third-generation sfermion masses

  16. Lingering single-strand breaks trigger Rad51-independent homology-directed repair of collapsed replication forks in the polynucleotide kinase/phosphatase mutant of fission yeast.

    Directory of Open Access Journals (Sweden)

    Arancha Sanchez

    2017-09-01

    Full Text Available The DNA repair enzyme polynucleotide kinase/phosphatase (PNKP protects genome integrity by restoring ligatable 5'-phosphate and 3'-hydroxyl termini at single-strand breaks (SSBs. In humans, PNKP mutations underlie the neurological disease known as MCSZ, but these individuals are not predisposed for cancer, implying effective alternative repair pathways in dividing cells. Homology-directed repair (HDR of collapsed replication forks was proposed to repair SSBs in PNKP-deficient cells, but the critical HDR protein Rad51 is not required in PNKP-null (pnk1Δ cells of Schizosaccharomyces pombe. Here, we report that pnk1Δ cells have enhanced requirements for Rad3 (ATR/Mec1 and Chk1 checkpoint kinases, and the multi-BRCT domain protein Brc1 that binds phospho-histone H2A (γH2A at damaged replication forks. The viability of pnk1Δ cells depends on Mre11 and Ctp1 (CtIP/Sae2 double-strand break (DSB resection proteins, Rad52 DNA strand annealing protein, Mus81-Eme1 Holliday junction resolvase, and Rqh1 (BLM/WRN/Sgs1 DNA helicase. Coupled with increased sister chromatid recombination and Rad52 repair foci in pnk1Δ cells, these findings indicate that lingering SSBs in pnk1Δ cells trigger Rad51-independent homology-directed repair of collapsed replication forks. From these data, we propose models for HDR-mediated tolerance of persistent SSBs with 3' phosphate in pnk1Δ cells.

  17. Uniform Single Valued Neutrosophic Graphs

    Directory of Open Access Journals (Sweden)

    S. Broumi

    2017-09-01

    Full Text Available In this paper, we propose a new concept named the uniform single valued neutrosophic graph. An illustrative example and some properties are examined. Next, we develop an algorithmic approach for computing the complement of the single valued neutrosophic graph. A numerical example is demonstrated for computing the complement of single valued neutrosophic graphs and uniform single valued neutrosophic graph.

  18. Using 3-color chromosome painting to decide between chromosome aberration models

    International Nuclear Information System (INIS)

    Lucas, J.N.; Sachs, R.K.

    1993-01-01

    Ionizing radiation produces chromosome aberrations when DNA double strand breaks (DSB) interact pairwise. For more than 30 years there have been two main, competing theories of such binary DSB interactions. The classical theory asserts that an unrepaired DSB makes two ends which separate, with each end subsequently able to join any similar (non-telomeric) end. The exchange theory asserts that the two DSB ends remain associated until repair or a reciprocal chromosome exchange involving a second DSB occurs. The authors conducted an experiment to test these models, using 3-color chromosome painting. After in vitro irradiation of resting human lymphocytes, they observed cells with three-color triplets at first metaphase: three derivative chromosomes having permuted colors, as if three broken chromosomes had played musical chairs. On the exchange model in its standard form such 3-color triplets cannot occur. On the classical model the expected frequency can be calculated. They report data and computer calculations which exclude the exchange model and favor the classical model

  19. Single Electrode Heat Effects

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Broers, G. H. J.

    1977-01-01

    The heat evolution at a single irreversibly working electrode is treated onthe basis of the Brønsted heat principle. The resulting equation is analogous to the expression for the total heat evolution in a galvanic cellwith the exception that –DeltaS is substituted by the Peltier entropy, Delta......SP, of theelectrode reaction. eta is the overvoltage at the electrode. This equation is appliedto a high temperature carbonate fuel cell. It is shown that the Peltier entropyterm by far exceeds the heat production due to the irreversible losses, and thatthe main part of heat evolved at the cathode is reabsorbed...

  20. Single-borehole techniques

    International Nuclear Information System (INIS)

    Klotz, D.; Moser, H.; Trimborn, P.

    1978-01-01

    Proceeding on the theoretical considerations and on the experience and practice derived from laboratory and field testing, a system consisting of tracer injection units, detector units, measuring probe units and packers is presented, from which the different borehole probes required can be combined. A couple of examples of recent applications shows the position of the Single-Borehole Techniques with respect to the traditional methods used for the measurement of the ground-water flow. A confrontation of the permeabilities of different aquifers consents, both on the basis of the Single-Borehole Techniques as by pumping experiments, the determination of the reliability of the Point-Dilution-Method. The Point-Dilution-Method is giving information about the vertical and horizontal distribution of the permeabilities in an aquifer. By measuring the vertical current in two karst wells, the tributary horizons of a well have been determined, which gave valuable information for the subsequent well construction. Local leakages could be detected by measuring the vertical flow rate through observation wells arranged along a grout curtain erected on both sides of the retaining barrage of the Keban dam. (orig.) [de

  1. Single photons on demand

    International Nuclear Information System (INIS)

    Grangier, P.; Abram, I.

    2004-01-01

    Quantum cryptography and information processing are set to benefit from developments in novel light sources that can emit photons one by one. Quantum mechanics has gained a reputation for making counter-intuitive predictions. But we rarely get the chance to witness these effects directly because, being humans, we are simply too big. Take light, for example. The light sources that are familiar to us, such as those used in lighting and imaging or in CD and DVD players, are so huge that they emit billions and billions of photons. But what if there was a light source that emitted just one photon at a time? Over the past few years, new types of light source that are able to emit photons one by one have been emerging from laboratories around the world. Pulses of light composed of a single photon correspond to power flows in the femtowatt range - a million billion times less than that of a table lamp. The driving force behind the development of these single-photon sources is a range of novel applications that take advantage of the quantum nature of light. Quantum states of superposed and entangled photons could lead the way to guaranteed-secure communication, to information processing with unprecedented speed and efficiency, and to new schemes for quantum teleportation. (U.K.)

  2. Single snapshot DOA estimation

    Science.gov (United States)

    Häcker, P.; Yang, B.

    2010-10-01

    In array signal processing, direction of arrival (DOA) estimation has been studied for decades. Many algorithms have been proposed and their performance has been studied thoroughly. Yet, most of these works are focused on the asymptotic case of a large number of snapshots. In automotive radar applications like driver assistance systems, however, only a small number of snapshots of the radar sensor array or, in the worst case, a single snapshot is available for DOA estimation. In this paper, we investigate and compare different DOA estimators with respect to their single snapshot performance. The main focus is on the estimation accuracy and the angular resolution in multi-target scenarios including difficult situations like correlated targets and large target power differences. We will show that some algorithms lose their ability to resolve targets or do not work properly at all. Other sophisticated algorithms do not show a superior performance as expected. It turns out that the deterministic maximum likelihood estimator is a good choice under these hard conditions.

  3. 75 FR 9247 - Single Family Mortgage Insurance Premium, Single Family

    Science.gov (United States)

    2010-03-01

    ... DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT [Docket No. FR-5376-N-13] Single Family Mortgage Insurance Premium, Single Family AGENCY: Office of the Chief Information Officer, HUD. ACTION: Notice... is soliciting public comments on the subject proposal. Lenders use the Single Family Premium...

  4. Lanthanide single molecule magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jinkui; Zhang, Peng [Chinese Academy of Sciences, Changchun (China). Changchun Inst. of Applied Chemistry

    2015-10-01

    This book begins by providing basic information on single-molecule magnets (SMMs), covering the magnetism of lanthanide, the characterization and relaxation dynamics of SMMs and advanced means of studying lanthanide SMMs. It then systematically introduces lanthanide SMMs ranging from mononuclear and dinuclear to polynuclear complexes, classifying them and highlighting those SMMs with high barrier and blocking temperatures - an approach that provides some very valuable indicators for the structural features needed to optimize the contribution of an Ising type spin to a molecular magnet. The final chapter presents some of the newest developments in the lanthanide SMM field, such as the design of multifunctional and stimuli-responsive magnetic materials as well as the anchoring and organization of the SMMs on surfaces. In addition, the crystal structure and magnetic data are clearly presented with a wealth of illustrations in each chapter, helping newcomers and experts alike to better grasp ongoing trends and explore new directions.

  5. Lanthanide single molecule magnets

    CERN Document Server

    Tang, Jinkui

    2015-01-01

    This book begins by providing basic information on single-molecule magnets (SMMs), covering the magnetism of lanthanide, the characterization and relaxation dynamics of SMMs, and advanced means of studying lanthanide SMMs. It then systematically introduces lanthanide SMMs ranging from mononuclear and dinuclear to polynuclear complexes, classifying them and highlighting those SMMs with high barrier and blocking temperatures – an approach that provides some very valuable indicators for the structural features needed to optimize the contribution of an Ising type spin to a molecular magnet. The final chapter presents some of the newest developments in the lanthanide SMM field, such as the design of multifunctional and stimuli-responsive magnetic materials as well as the anchoring and organization of the SMMs on surfaces. In addition, the crystal structure and magnetic data are clearly presented with a wealth of illustrations in each chapter, helping newcomers and experts alike to better grasp ongoing trends and...

  6. Single access laparoscopic nephrectomy

    Directory of Open Access Journals (Sweden)

    Jay D Raman

    2008-01-01

    Full Text Available Laparoscopic nephrectomy has assumed a central role in the management of benign and malignant kidney diseases. While laparoscopy is less morbid than open surgery, it still requires several incisions each at least 1-2 cm in length. Each incision carries morbidity risks of bleeding, hernia and/or internal organ damage, and incrementally decreases cosmesis. An alternative to conventional laparoscopy is single access or keyhole surgery, which utilizes magnetic anchoring and guidance system (MAGS technology or articulating laparoscopic instruments. These technical innovations obviate the need to externally space trocars for triangulation, thus allowing for the creation of a small, solitary portal of entry into the abdomen. Laboratory and early clinical series demonstrate feasibility as well as safe and successful completion of keyhole nephrectomy. Future work is necessary to improve existing instrumentation, increase clinical experience, assess benefits of this surgical approach, and explore other potential applications for this technique.

  7. Single-Molecule Nanomagnets

    Science.gov (United States)

    Friedman, Jonathan R.; Sarachik, Myriam P.

    2010-04-01

    Single-molecule magnets straddle the classical and quantum mechanical worlds, displaying many fascinating phenomena. They may have important technological applications in information storage and quantum computation. We review the physical properties of two prototypical molecular nanomagnets, Mn12-acetate and Fe8: Each behaves as a rigid, spin-10 object and exhibits tunneling between up and down directions. As temperature is lowered, the spin-reversal process evolves from thermal activation to pure quantum tunneling. At low temperatures, magnetic avalanches occur in which the magnetization of an entire sample rapidly reverses. We discuss the important role that symmetry-breaking fields play in driving tunneling and in producing Berry-phase interference. Recent experimental advances indicate that quantum coherence can be maintained on timescales sufficient to allow a meaningful number of quantum computing operations to be performed. Efforts are under way to create monolayers and to address and manipulate individual molecules.

  8. Assessment of single nucleotide polymorphisms in screening 52 DNA repair and cell cycle control genes in Fanconi anemia patients

    Directory of Open Access Journals (Sweden)

    Petrović Sandra

    2015-01-01

    Full Text Available Fanconi anemia (FA is a rare genetically heterogeneous disorder associated with bone marrow failure, birth defects and cancer susceptibility. Apart from the disease- causing mutations in FANC genes, the identification of specific DNA variations, such as single nucleotide polymorphisms (SNPs, in other candidate genes may lead to a better clinical description of this condition enabling individualized treatment with improvement of the prognosis. In this study, we have assessed 95 SNPs located in 52 key genes involved in base excision repair (BER, nucleotide excision repair (NER, mismatch repair (MMR, double strand break (DSB repair and cell cycle control using a DNA repair chip (Asper Biotech, Estonia which includes most of the common variants for the candidate genes. The SNP genotyping was performed in five FA-D2 patients and in one FA-A patient. The polymorphisms studied were synonymous (n=10, nonsynonymous (missense (n=52 and in non-coding regions of the genome (introns and 5 ‘and 3’ untranslated regions (UTR (n=33. Polymorphisms found at the homozygous state are selected for further analysis. Our results have shown a significant inter-individual variability among patients in the type and the frequency of SNPs and also elucidate the need for further studies of polymorphisms located in ATM, APEX APE 1, XRCC1, ERCC2, MSH3, PARP4, NBS1, BARD1, CDKN1B, TP53 and TP53BP1 which may be of great importance for better clinical description of FA. In addition, the present report recommends the use of SNPs as predictive and prognostic genetic markers to individualize therapy of FA patients. [Projekat Ministarstva nauke Republike Srbije, br. 173046

  9. The role of the Mre11–Rad50–Nbs1 complex in double-strand break repair—facts and myths

    International Nuclear Information System (INIS)

    Takeda, Shunichi; Hoa, Nguyen Ngoc; Sasanuma, Hiroyuki

    2016-01-01

    Homologous recombination (HR) initiates double-strand break (DSB) repair by digesting 5′-termini at DSBs, the biochemical reaction called DSB resection, during which DSBs are processed by nucleases to generate 3′ single-strand DNA. Rad51 recombinase polymerizes along resected DNA, and the resulting Rad51–DNA complex undergoes homology search. Although DSB resection by the Mre11 nuclease plays a critical role in HR in Saccharomyces cerevisiae, it remains elusive whether DSB resection by Mre11 significantly contributes to HR-dependent DSB repair in mammalian cells. Depletion of Mre11 decreases the efficiency of DSB resection only by 2- to 3-fold in mammalian cells. We show that although Mre11 is required for efficient HR-dependent repair of ionizing-radiation–induced DSBs, Mre11 is largely dispensable for DSB resection in both chicken DT40 and human TK6 B cell lines. Moreover, a 2- to 3-fold decrease in DSB resection has virtually no impact on the efficiency of HR. Thus, although a large number of researchers have reported the vital role of Mre11-mediated DSB resection in HR, the role may not explain the very severe defect in HR in Mre11-deficient cells, including their lethality. We here show experimental evidence for the additional roles of Mre11 in (i) elimination of chemical adducts from DSB ends for subsequent DSB repair, and (ii) maintaining HR intermediates for their proper resolution

  10. Regular Single Valued Neutrosophic Hypergraphs

    Directory of Open Access Journals (Sweden)

    Muhammad Aslam Malik

    2016-12-01

    Full Text Available In this paper, we define the regular and totally regular single valued neutrosophic hypergraphs, and discuss the order and size along with properties of regular and totally regular single valued neutrosophic hypergraphs. We also extend work on completeness of single valued neutrosophic hypergraphs.

  11. Single particle detecting telescope system

    International Nuclear Information System (INIS)

    Yamamoto, I.; Tomiyama, T.; Iga, Y.; Komatsubara, T.; Kanada, M.; Yamashita, Y.; Wada, T.; Furukawa, S.

    1981-01-01

    We constructed the single particle detecting telescope system for detecting a fractionally charged particle. The telescope consists of position detecting counters, wall-less multi-cell chambers, single detecting circuits and microcomputer system as data I/0 processor. Especially, a frequency of double particle is compared the case of the single particle detecting with the case of an ordinary measurement

  12. Single atom spintronics

    International Nuclear Information System (INIS)

    Sullivan, M. R.; Armstrong, J. N.; Hua, S. Z.; Chopra, H. D.

    2005-01-01

    Full text: Single atom spintronics (SASS) represents the ultimate physical limit in device miniaturization. SASS is characterized by ballistic electron transport, and is a fertile ground for exploring new phenomena. In addition to the 'stationary' (field independent) scattering centers that have a small and fixed contribution to total transmission probability of electron waves, domain walls constitute an additional and enhanced source of scattering in these magnetic quantum point contacts (QPCs), the latter being both field and spin-dependent. Through the measurement of complete hysteresis loops as a function of quantized conductance, we present definitive evidence of enhanced backscattering of electron waves by atomically sharp domain walls in QPCs formed between microfabricated thin films [1]. Since domain walls move in a magnetic field, the magnitude of spin-dependent scattering changes as the QPC is cycled along its hysteresis loop. For example, as shown in the inset in Fig. 1, from zero towards saturation in a given field direction, the resistance varies as the wall is being swept away, whereas the resistance is constant upon returning from saturation towards zero, since in this segment of the hysteresis loop no domain wall is present across the contact. The observed spin-valve like behavior is realized by control over wall width and shape anisotropy. This behavior also unmistakably sets itself apart from any mechanical artifacts; additionally, measurements made on single atom contacts provide an artifact-free environment [2]. Intuitively, it is simpler to organize the observed BMR data according to all possible transitions between different conductance plateaus, as shown by the dotted line in Fig. 1; the solid circles show experimental data for Co, which follows the predicted scheme. Requisite elements for the observation of the effect will be discussed in detail along with a review of state of research in this field. Practically, the challenge lies in making

  13. A single particle energies

    Energy Technology Data Exchange (ETDEWEB)

    Bodmer, A.R. [Illinois Univ., Chicago, IL (United States). Dept. of Physics]|[Argonne National Lab., IL (United States); Usmani, Q.N.; Sami, M. [Jamia Millia Islamia, New Delhi (India). Dept. of Physics

    1993-09-01

    We consider the binding energies of {Lambda} hypernuclei (HN), in particular the single-particle (s.p.) energy data, which have been obtained for a wide range of HN with mass numbers A {le} 89 and for orbital angular momenta {ell}{sub {Lambda}} {le} 4. We briefly review some of the relevant properties of A hypernuclei. These are nuclei {sub {Lambda}}{sup A}Z with baryon number A in which a single {Lambda} hyperon (baryon number = 1) is bound to an ordinary nucleus {sup A}Z consisting of A - 1 nucleons = Z protons + N neutrons. The {Lambda} hyperon is neutral, has spin 1/2, strangeness S = {minus}1, isospin I = O and a mass M{sub {Lambda}} = 1116 MeV/c{sup 2}. Although the {Lambda} interacts with a nucleon, its interaction is only about half as strong as that between two nucleons, and thus very roughly V{sub {Lambda}N} {approx} 0.5 V{sub NN}. As a result, the two-body {Lambda}N system is unbound, and the lightest bound HN is the three-body hypertriton {sub {Lambda}}{sup 3}H in which the {Lambda} is bound to a deuteron with the {Lambda}-d separation energy being only {approx} 0.1 MeV corresponding to an exponential tail of radius {approx} 15 fm! In strong interactions the strangeness S is of course conserved, and the {Lambda} is distinct from the nucleons. In a HN strangeness changes only in the weak decays of the {Lambda} which can decay either via ``free`` pionic decay {Lambda} {yields} N + {pi} or via induced decay {Lambda} + N {yields} N + N which is only possible in the presence of nucleons. Because of the small energy release the pionic decay is strongly suppressed in all but the lightest HN and the induced decay dominates. However, the weak decay lifetime {approx} 10{sup {minus}10}s is in fact close to the lifetime of a free {Lambda}. Since this is much longer than the strong interaction time {approx} 10{sup {minus}22}s we can ignore the weak interactions when considering the binding of HN, just as for ordinary nuclei.

  14. A single particle energies

    International Nuclear Information System (INIS)

    Bodmer, A.R.; Usmani, Q.N.; Sami, M.

    1993-01-01

    We consider the binding energies of Λ hypernuclei (HN), in particular the single-particle (s.p.) energy data, which have been obtained for a wide range of HN with mass numbers A ≤ 89 and for orbital angular momenta ell Λ ≤ 4. We briefly review some of the relevant properties of A hypernuclei. These are nuclei Λ A Z with baryon number A in which a single Λ hyperon (baryon number = 1) is bound to an ordinary nucleus A Z consisting of A - 1 nucleons = Z protons + N neutrons. The Λ hyperon is neutral, has spin 1/2, strangeness S = -1, isospin I = O and a mass M Λ = 1116 MeV/c 2 . Although the Λ interacts with a nucleon, its interaction is only about half as strong as that between two nucleons, and thus very roughly V ΛN ∼ 0.5 V NN . As a result, the two-body ΛN system is unbound, and the lightest bound HN is the three-body hypertriton Λ 3 H in which the Λ is bound to a deuteron with the Λ-d separation energy being only ∼ 0.1 MeV corresponding to an exponential tail of radius ∼ 15 fm exclamation point In strong interactions the strangeness S is of course conserved, and the Λ is distinct from the nucleons. In a HN strangeness changes only in the weak decays of the Λ which can decay either via ''free'' pionic decay Λ → N + π or via induced decay Λ + N → N + N which is only possible in the presence of nucleons. Because of the small energy release the pionic decay is strongly suppressed in all but the lightest HN and the induced decay dominates. However, the weak decay lifetime ∼ 10 -10 s is in fact close to the lifetime of a free Λ. Since this is much longer than the strong interaction time ∼ 10 -22 s we can ignore the weak interactions when considering the binding of HN, just as for ordinary nuclei

  15. The single entity option

    International Nuclear Information System (INIS)

    Friedlander, M.C.; Roberts, K.M.

    1997-01-01

    Traditionally, an owner hires an engineer to design a power facility or other project and then circulates the completed plans to several contractors for competitive bidding. Although there are many variations on this theme, there is an alternative method which is growing in popularity--the design-build concept. In this construction method, the same entity designs and constructs the facility. The design builder may be a single firm with both design and construction capacity in-house, or it may be a combination of two or more firms with complementary abilities. If there are multiple firms, they may be structured as a joint venture or with one of the firms prime and the others in a subcontracting role. The critical aspect is that the owner contracts with one entity which has the responsibility for both designing and constructing the facility. According to statistics compiled by the Design-Build Institute of America and F.W. Dodge DATALINE2, a national reporter of construction statistics and information, from April 1995 to April 1996 the number of design-build contracts increased 103 percent over the previous year. Of a total $212 billion construction market, about $37.2 billion--18 percent--was design build. The strongest growth was in the category of industrial--plants, refineries, factories and warehouses--in which the concept use was up more than 300 percent from the previous year

  16. Single-photon sources based on single molecules in solids

    International Nuclear Information System (INIS)

    Moerner, W E

    2004-01-01

    Single molecules in suitable host crystals have been demonstrated to be useful single-photon emitters both at liquid-helium temperatures and at room temperature. The low-temperature source achieved controllable emission of single photons from a single terrylene molecule in p-terphenyl by an adiabatic rapid passage technique. In contrast with almost all other single-molecule systems, terrylene single molecules show extremely high photostability under continuous, high-intensity irradiation. A room-temperature source utilizing this material has been demonstrated, in which fast pumping into vibrational sidebands of the electronically excited state achieved efficient inversion of the emissive level. This source yielded a single-photon emission probability p(1) of 0.86 at a detected count rate near 300 000 photons s -1 , with very small probability of emission of more than one photon. Thus, single molecules in solids can be considered as contenders for applications of single-photon sources such as quantum key distribution

  17. Effects of DNA double-strand and single-strand breaks on intrachromosomal recombination events in cell-cycle-arrested yeast cells

    International Nuclear Information System (INIS)

    Galli, A.; Schiestl, R.H.

    1998-01-01

    Intrachromosomal recombination between repeated elements can result in deletion (DEL recombination) events. We investigated the inducibility of such intrachromosomal recombination events at different stages of the cell cycle and the nature of the primary DNA lesions capable of initiating these events. Two genetic systems were constructed in Saccharomyces cerevisiae that select for DEL recombination events between duplicated alleles of CDC28 and TUB2. We determined effects of double-strand breaks (DSBs) and single-strand breaks (SSBs) between the duplicated alleles on DEL recombination when induced in dividing cells or cells arrested in G1 or G2. Site-specific DSBs and SSBs were produced by overexpression of the I-Sce I endonuclease and the gene II protein (gIIp), respectively. I-Sce I-induced DSBs caused an increase in DEL recombination frequencies in both dividing and cell-cycle-arrested cells, indicating that G1- and G2-arrested cells are capable of completing DSB repair. In contrast, gIIp-induced SSBs caused an increase in DEL recombination frequency only in dividing cells. To further examine these phenomena we used both γ-irradiation, inducing DSBs as its most relevant lesion, and UV, inducing other forms of DNA damage. UV irradiation did not increase DEL recombination frequencies in G1 or G2, whereas γ-rays increased DEL recombination frequencies in both phases. Both forms of radiation, however, induced DEL recombination in dividing cells. The results suggest that DSBsbut not SSBs induce DEL recombination, probably via the single-strand annealing pathway. Further, DSBs in dividing cells may result from the replication of a UV or SSB-damaged template. Alternatively, UV induced events may occur by replication slippage after DNA polymerase pausing in front of the damage. (author)

  18. Advances in single chain technology.

    Science.gov (United States)

    Gonzalez-Burgos, Marina; Latorre-Sanchez, Alejandro; Pomposo, José A

    2015-10-07

    The recent ability to manipulate and visualize single atoms at atomic level has given rise to modern bottom-up nanotechnology. Similar exquisite degree of control at the individual polymeric chain level for producing functional soft nanoentities is expected to become a reality in the next few years through the full development of so-called "single chain technology". Ultra-small unimolecular soft nano-objects endowed with useful, autonomous and smart functions are the expected, long-term valuable output of single chain technology. This review covers the recent advances in single chain technology for the construction of soft nano-objects via chain compaction, with an emphasis in dynamic, letter-shaped and compositionally unsymmetrical single rings, complex multi-ring systems, single chain nanoparticles, tadpoles, dumbbells and hairpins, as well as the potential end-use applications of individual soft nano-objects endowed with useful functions in catalysis, sensing, drug delivery and other uses.

  19. Nanodiamond Emitters of Single Photons

    Directory of Open Access Journals (Sweden)

    Vlasov I.I.

    2015-01-01

    Full Text Available Luminescence properties of single color centers were studied in nanodiamonds of different origin. It was found that single photon emitters could be realized even in molecularsized diamond (less than 2 nm capable of housing stable luminescent center “silicon-vacancy.” First results on incorporation of single-photon emitters based on luminescent nanodiamonds in plasmonic nanoantennas to enhance the photon count rate and directionality, diminish the fluorescence decay time, and provide polarization selectivity are presented.

  20. Correlation between cell survival and DNA single-strand break repair proficiency in the Chinese hamster ovary cell lines AA8 and EM9 irradiated with 365-nm ultraviolet-A radiation

    Energy Technology Data Exchange (ETDEWEB)

    Churchill, M.E.; Peak, J.G.; Peak, M.J. (Argonne National Lab., IL (USA))

    1991-02-01

    Cell survival parameters and the induction and repair of DNA single-strand breaks were measured in two Chinese hamster ovary cell lines after irradiation with monochromatic UVA radiation of wavelength 365 nm. The radiosensitive mutant cell line EM9 is known to repair ionizing-radiation-induced single-strand breaks (SSB) more slowly than the parent line AA8. EM9 was determined to be 1.7-fold more sensitive to killing by 365-nm radiation than AA8 at the 10% survival level, and EM9 had a smaller shoulder region on the survival curve ({alpha} = 1.76) than AA8 ({alpha} = 0.62). No significant differences were found between the cell lines in the initial yields of SSB induced either by {gamma}-radiation (as determined by alkaline sucrose gradient sedimentation) or by 365-nm UVA (as determined by alkaline elution). For measurement of initial SSB, cells were irradiated at 0.5{sup o}C to minimize DNA repair processes. Rejoining of 365-nm induced SSB was measured by irradiating cells at 0.5{sup o}C, allowing them to repair at 37{sup o}C in full culture medium, and then quantitating the remaining SSB by alkaline elution. The repair of these breaks followed biphasic kinetics in both cell lines. EM9 repaired the breaks more slowly (T{sub 1/2} values of 1.3 and 61.3 min) than did AA8 (T{sub 1/2} values of 0.9 and 53.3 min), and EM9 also left more breaks unrepaired 90 min after irradiation (24% vs 8% for AA8). Thus, the sensitivity of EM9 to 365-nm radiation correlated with its deficiency in repairing DNA lesions revealed as SSB in alkaline elution. These results suggest that DNA may be a critical target in 365-nm induced cellular lethality and that the ability of AA8 and EM9 cells to repair DNA strand breaks may be related to their ability to survive 365-nm radiation. (author).

  1. The contribution of thermally labile sugar lesions to DNA double-strand break formation in cells grown in the presence of BrdU.

    Science.gov (United States)

    Li, Fanghua; Cheng, Yanlei; Iliakis, George

    2015-04-01

    Radiosensitization by bromodeoxyuridine (BrdU) is commonly attributed to an increase in the yield of double-strand breaks (DSB) in the DNA and an associated decrease in the reparability of these lesions. Radiation chemistry provides a mechanism for the increased yield of DSB through the generation, after bromine loss, of a highly reactive uracilyl radical that attacks the sugar moiety of the nucleotide to produce a single-strand break (SSB). The effects underpinning DSB repair inhibition remain, in contrast, incompletely characterized. A possible source of reduced reparability is a change in the nature or complexity of the DSB in BrdU-substituted DNA. Recent studies show that DSB-complexity or DSB-nature may also be affected by the presence within the cluster of thermally labile sugar lesions (TLSL) that break the DNA backbone only if they chemically evolve to SSB, a process thought to occur within the first hour post-irradiation. Since BrdU radiosensitization might be associated with increased yields and reduced reparability of DSB, we investigated whether BrdU underpins these effects by shifting the balance in the generation of TLSL. We employed asymmetric-field-inversion gel electrophoresis (AFIGE), a pulsed-field gel electrophoresis (PFGE) method to quantitate DSB in a battery of five cells lines grown in the presence of different concentrations of BrdU. We measured specifically the yields of promptly forming DSB (prDSB) using low temperature lysis protocols, and the yields of total DSB (tDSB = prDSB + tlDSB; tlDSB form after evolution to SSB of TLSL) using high temperature lysis protocols. We report that incorporation of BrdU generates similar increases in the formation of tlDSB and prDSB, but variations are noted among the different cell lines tested. The similar increase in the yields of tlDSB and prDSB in BrdU substituted DNA showed that shifts in the yields of these forms of lesions could not be invoked to explain BrdU radiosensitization.

  2. Single photon sources with single semiconductor quantum dots

    Science.gov (United States)

    Shan, Guang-Cun; Yin, Zhang-Qi; Shek, Chan Hung; Huang, Wei

    2014-04-01

    In this contribution, we briefly recall the basic concepts of quantum optics and properties of semiconductor quantum dot (QD) which are necessary to the understanding of the physics of single-photon generation with single QDs. Firstly, we address the theory of quantum emitter-cavity system, the fluorescence and optical properties of semiconductor QDs, and the photon statistics as well as optical properties of the QDs. We then review the localization of single semiconductor QDs in quantum confined optical microcavity systems to achieve their overall optical properties and performances in terms of strong coupling regime, efficiency, directionality, and polarization control. Furthermore, we will discuss the recent progress on the fabrication of single photon sources, and various approaches for embedding single QDs into microcavities or photonic crystal nanocavities and show how to extend the wavelength range. We focus in particular on new generations of electrically driven QD single photon source leading to high repetition rates, strong coupling regime, and high collection efficiencies at elevated temperature operation. Besides, new developments of room temperature single photon emission in the strong coupling regime are reviewed. The generation of indistinguishable photons and remaining challenges for practical single-photon sources are also discussed.

  3. Do single women value early retirement more than single men?

    DEFF Research Database (Denmark)

    Danø, Anne Møller; Ejrnæs, Mette; Husted, Leif

    2005-01-01

    and health are important determinants of the retirement decision. Furthermore, we find substantial gender differences in the retirement pattern. Healthy single women value retirement more than healthy single men and are willing to reduce their disposable income to 74% of their previous income while men......The focus of this paper is to analyse why a large fraction of single elderly people choose to retire early. A structural model directly based on the individual decision of labour supply is estimated on a sample of singles, where singles are defined as those who are living alone. We find that income...... are willing to reduce the income to 81%. Men's retirement decision is mainly influenced by income and health, whereas women's retirement decision is also affected by education and unemployment experience...

  4. Quantum optics with single quantum dot devices

    International Nuclear Information System (INIS)

    Zwiller, Valery; Aichele, Thomas; Benson, Oliver

    2004-01-01

    A single radiative transition in a single-quantum emitter results in the emission of a single photon. Single quantum dots are single-quantum emitters with all the requirements to generate single photons at visible and near-infrared wavelengths. It is also possible to generate more than single photons with single quantum dots. In this paper we show that single quantum dots can be used to generate non-classical states of light, from single photons to photon triplets. Advanced solid state structures can be fabricated with single quantum dots as their active region. We also show results obtained on devices based on single quantum dots

  5. Single-Gender Schools Scrutinized

    Science.gov (United States)

    Zubrzycki, Jaclyn

    2012-01-01

    This article reports on a study on publicly run schools in the Republic of Trinidad and Tobago which has found that, while single-sex schools may benefit female students who prefer a single-sex environment, they are not inherently beneficial for boys or most girls. While the findings are based on data from one Caribbean nation, experts say they…

  6. Single top t-channel

    CERN Document Server

    Faltermann, Nils

    2017-01-01

    The production of single top quarks allows to study the interplay of top quark physics and the electroweak sector of the standard model. Deviations from predictions can be a hint for physics beyond the standard model. The t-channel is the dominant production mode for single top quarks at the LHC. This talk presents the latest measurements from the ATLAS and CMS collaborations.

  7. Single-electron charging effects

    International Nuclear Information System (INIS)

    Ruggiero, S.T.

    1990-01-01

    The status of our project on single-electron tunneling is at this point excellent. As outlined in our original proposal, a key goal in the development of this project was the demonstration and exploration of the microwave properties of single-electron systems. As discussed here, such work has to date been carried out

  8. miR-24-mediated down-regulation of H2AX suppresses DNA repair in terminally differentiated blood cells

    Science.gov (United States)

    Lal, Ashish; Pan, Yunfeng; Navarro, Francisco; Dykxhoorn, Derek M.; Moreau, Lisa; Meire, Eti; Bentwich, Zvi; Lieberman, Judy; Chowdhury, Dipanjan

    2010-01-01

    Terminally differentiated cells have reduced capacity to repair double strand breaks (DSB), but the molecular mechanism behind this down-regulation is unclear. Here we find that miR-24 is consistently up-regulated during post-mitotic differentiation of hematopoietic cell lines and regulates the histone variant H2AX, a key DSB repair protein that activates cell cycle checkpoint proteins and retains DSB repair factors at DSB foci. The H2AX 3’UTR contains conserved miR-24 binding sites regulated by miR-24. Both H2AX mRNA and protein are substantially reduced during hematopoietic cell terminal differentiation by miR-24 up-regulation both in in vitro differentiated cells and primary human blood cells. miR-24 suppression of H2AX renders cells hypersensitive to γ-irradiation and genotoxic drugs. Antagonizing miR-24 in differentiating cells protects them from DNA damage-induced cell death, while transfecting miR-24 mimics in dividing cells increases chromosomal breaks and unrepaired DNA damage and reduces viability in response to DNA damage. This DNA repair phenotype can be fully rescued by over-expressing miR-24-insensitive H2AX. Therefore, miR-24 up-regulation in post-replicative cells reduces H2AX and thereby renders them highly vulnerable to DNA damage. PMID:19377482

  9. Single banking supervision and the single supervisory mechanism

    Directory of Open Access Journals (Sweden)

    Gheorghe, C. A.

    2013-06-01

    Full Text Available A resolution seems to have been found for the banking crisis. The first steps have been made towards the construction of the Economic and Monetary Union, steps involving the single supervision of banks, in order to avoid the discount of a new financial crisis on the expense of the EU state members. The Single Supervisory Mechanism – SSM is to become effective as of March 1, 2014, at the earliest.

  10. Single Molecule Nano-Metronome

    OpenAIRE

    Buranachai, Chittanon; McKinney, Sean A.; Ha, Taekjip

    2006-01-01

    We constructed a DNA-based nano-mechanical device called the nano-metronome. Our device is made by introducing complementary single stranded overhangs at the two arms of the DNA four-way junction. The ticking rates of this stochastic metronome depend on ion concentrations and can be changed by a set of DNA-based switches to deactivate/reactivate the sticky end. Since the device displays clearly distinguishable responses even with a single basepair difference, it may lead to a single molecule ...

  11. Single Molecule Nano-Metronome

    Science.gov (United States)

    Buranachai, Chittanon; McKinney, Sean A.; Ha, Taekjip

    2008-01-01

    We constructed a DNA-based nano-mechanical device called the nano-metronome. Our device is made by introducing complementary single stranded overhangs at the two arms of the DNA four-way junction. The ticking rates of this stochastic metronome depend on ion concentrations and can be changed by a set of DNA-based switches to deactivate/reactivate the sticky end. Since the device displays clearly distinguishable responses even with a single basepair difference, it may lead to a single molecule sensor of minute sequence differences of a target DNA. PMID:16522050

  12. Longitudinal single-bunch instabilities

    International Nuclear Information System (INIS)

    Migliorati, M.; Palumbo, L.; Rome Univ. La Sapienza, Rome

    2001-02-01

    After introducing the concepts of longitudinal wakefield and coupling impedance, it is reviewed the theory of longitudinal single-bunch collective effects in storage rings. From the Fokker-Planck equation it is first derived the stationary solution describing the natural single-bunch regime, and then treat the problem of microwave instability, showing the different approaches used for estimating the threshold current. The lecture is ended with the semi-empirical laws that allow everyone to obtain the single-bunch behaviour above threshold, and with a description of the simulation codes that are now reliable tools for investigating all these effects

  13. Adverse selection without single crossing

    DEFF Research Database (Denmark)

    Schottmüller, Christoph

    2015-01-01

    The single-crossing assumption simplifies the analysis of screening models as local incentive compatibility becomes sufficient for global incentive compatibility. If single crossing is violated, global incentive compatibility constraints have to be taken into account. This paper studies monotone...... solutions in a screening model that allows a one-time violation of single crossing. The results show that local and non-local incentive constraints distort the solution in opposite directions. Therefore, the optimal decision might involve distortions above as well as below the first-best decision...

  14. Thermoelectric single-photon detector

    International Nuclear Information System (INIS)

    Kuzanyan, A A; Petrosyan, V A; Kuzanyan, A S

    2012-01-01

    The ability to detect a single photon is the ultimate level of sensitivity in the measurement of optical radiation. Sensors capable of detecting single photons and determining their energy have many scientific and technological applications. Kondo-enhanced Seebeck effect cryogenic detectors are based on thermoelectric heat-to-voltage conversion and voltage readout. We evaluate the prospects of CeB 6 and (La,Ce)B 6 hexaboride crystals for their application as a sensitive element in this type of detectors. We conclude that such detectors can register a single UV photon, have a fast count rate (up to 45 MHz) and a high spectral resolution of 0.1 eV. We calculate the electric potential generated along the thermoelectric sensor upon registering a UV single photon.

  15. Microfluidics for single cell analysis

    DEFF Research Database (Denmark)

    Jensen, Marie Pødenphant

    Isolation and manipulation of single cells have gained an increasing interest from researchers because of the heterogeneity of cells from the same cell culture. Single cell analysis can ensure a better understanding of differences between individual cells and potentially solve a variety of clinical...... problems. In this thesis lab on a chip systems for rare single cell analysis are investigated. The focus was to develop a commercial, disposable device for circulating tumour cell (CTC) analysis. Such a device must be able to separate rare cells from blood samples and subsequently capture the specific...... cells, and simultaneously be fabricated and operated at low costs and be user-friendly. These challenges were addressed through development of two microfluidic devices, one for rare cell isolation based on pinched flow fractionation (PFF) and one for single cell capture based on hydrodynamic trapping...

  16. Single-employer Pension Plans

    Data.gov (United States)

    Pension Benefit Guaranty Corporation — This spreadsheet lists the active single-employer pensions plans insured by PBGC. Plans are identified by name, employer identification number (EIN) and plan number...

  17. Single Sign On Internal (SSOi)

    Data.gov (United States)

    Department of Veterans Affairs — Provides single sign-on solution for internal facing VA applications. Allows internal users access to a variety of VA systems and applications using a reduced set of...

  18. Single nanoparticle tracking spectroscopic microscope

    Science.gov (United States)

    Yang, Haw [Moraga, CA; Cang, Hu [Berkeley, CA; Xu, Cangshan [Berkeley, CA; Wong, Chung M [San Gabriel, CA

    2011-07-19

    A system that can maintain and track the position of a single nanoparticle in three dimensions for a prolonged period has been disclosed. The system allows for continuously imaging the particle to observe any interactions it may have. The system also enables the acquisition of real-time sequential spectroscopic information from the particle. The apparatus holds great promise in performing single molecule spectroscopy and imaging on a non-stationary target.

  19. Approaches to single photon detection

    International Nuclear Information System (INIS)

    Thew, R.T.; Curtz, N.; Eraerds, P.; Walenta, N.; Gautier, J.-D.; Koller, E.; Zhang, J.; Gisin, N.; Zbinden, H.

    2009-01-01

    We present recent results on our development of single photon detectors, including: gated and free-running InGaAs/InP avalanche photodiodes (APDs); hybrid detection systems based on sum-frequency generation (SFG) and Si APDs-SFG-Si APDs; and SSPDs (superconducting single photon detectors), for telecom wavelengths; as well as SiPM (Silicon photomultiplier) detectors operating in the visible regime.

  20. IDN2 Interacts with RPA and Facilitates DNA Double-Strand Break Repair by Homologous Recombination in Arabidopsis.

    Science.gov (United States)

    Liu, Mingming; Ba, Zhaoqing; Costa-Nunes, Pedro; Wei, Wei; Li, Lanxia; Kong, Fansi; Li, Yan; Chai, Jijie; Pontes, Olga; Qi, Yijun

    2017-03-01

    Repair of DNA double-strand breaks (DSBs) is critical for the maintenance of genome integrity. We previously showed that DSB-induced small RNAs (diRNAs) facilitate homologous recombination-mediated DSB repair in Arabidopsis thaliana Here, we show that INVOLVED IN DE NOVO2 (IDN2), a double-stranded RNA binding protein involved in small RNA-directed DNA methylation, is required for DSB repair in Arabidopsis. We find that IDN2 interacts with the heterotrimeric replication protein A (RPA) complex. Depletion of IDN2 or the diRNA binding ARGONAUTE2 leads to increased accumulation of RPA at DSB sites and mislocalization of the recombination factor RAD51. These findings support a model in which IDN2 interacts with RPA and facilitates the release of RPA from single-stranded DNA tails and subsequent recruitment of RAD51 at DSB sites to promote DSB repair. © 2017 American Society of Plant Biologists. All rights reserved.

  1. Single particle tracking and single molecule energy transfer

    CERN Document Server

    Bräuchle, Christoph; Michaelis, Jens

    2009-01-01

    Closing a gap in the literature, this handbook gathers all the information on single particle tracking and single molecule energy transfer. It covers all aspects of this hot and modern topic, from detecting virus entry to membrane diffusion, and from protein folding using spFRET to coupled dye systems, as well recent achievements in the field. Throughout, the first-class editors and top international authors present content of the highest quality, making this a must-have for physical chemists, spectroscopists, molecular physicists and biochemists.

  2. Control of Single-Stage Single-Phase PV inverter

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Blaabjerg, Frede

    2005-01-01

    In this paper the issue of control strategies for single-stage photovoltaic (PV) inverter is addressed. Two different current controllers have been implemented and an experimental comparison between them has been made. A complete control structure for the single-phase PV system is also presented......-forward; - and the grid current controller implemented in two different ways, using the classical proportional integral (PI) and the novel proportional resonant (PR) controllers. The control strategy was tested experimentally on 1.5 kW PV inverter....

  3. Single-tier city logistics model for single product

    Science.gov (United States)

    Saragih, N. I.; Nur Bahagia, S.; Suprayogi; Syabri, I.

    2017-11-01

    This research develops single-tier city logistics model which consists of suppliers, UCCs, and retailers. The problem that will be answered in this research is how to determine the location of UCCs, to allocate retailers to opened UCCs, to assign suppliers to opened UCCs, to control inventory in the three entities involved, and to determine the route of the vehicles from opened UCCs to retailers. This model has never been developed before. All the decisions will be simultaneously optimized. Characteristic of the demand is probabilistic following a normal distribution, and the number of product is single.

  4. Single Molecule Electronics and Devices

    Science.gov (United States)

    Tsutsui, Makusu; Taniguchi, Masateru

    2012-01-01

    The manufacture of integrated circuits with single-molecule building blocks is a goal of molecular electronics. While research in the past has been limited to bulk experiments on self-assembled monolayers, advances in technology have now enabled us to fabricate single-molecule junctions. This has led to significant progress in understanding electron transport in molecular systems at the single-molecule level and the concomitant emergence of new device concepts. Here, we review recent developments in this field. We summarize the methods currently used to form metal-molecule-metal structures and some single-molecule techniques essential for characterizing molecular junctions such as inelastic electron tunnelling spectroscopy. We then highlight several important achievements, including demonstration of single-molecule diodes, transistors, and switches that make use of electrical, photo, and mechanical stimulation to control the electron transport. We also discuss intriguing issues to be addressed further in the future such as heat and thermoelectric transport in an individual molecule. PMID:22969345

  5. Resolution of Single Spin-Flips of a Single Proton

    CERN Document Server

    Mooser, A.; Blaum, K.; Bräuninger, S.A.; Franke, K.; Leiteritz, C.; Quint, W.; Rodegheri, C.C.; Ulmer, S.; Walz, J.

    2013-04-04

    The spin magnetic moment of a single proton in a cryogenic Penning trap was coupled to the particle's axial motion with a superimposed magnetic bottle. Jumps in the oscillation frequency indicate spin-flips and were identified using a Bayesian analysis.

  6. A multistep single-crystal-to-single-crystal bromodiacetylene dimerization

    Science.gov (United States)

    Hoheisel, Tobias N.; Schrettl, Stephen; Marty, Roman; Todorova, Tanya K.; Corminboeuf, Clémence; Sienkiewicz, Andrzej; Scopelliti, Rosario; Schweizer, W. Bernd; Frauenrath, Holger

    2013-04-01

    Packing constraints and precise placement of functional groups are the reason that organic molecules in the crystalline state often display unusual physical or chemical properties not observed in solution. Here we report a single-crystal-to-single-crystal dimerization of a bromodiacetylene that involves unusually large atom displacements as well as the cleavage and formation of several bonds. Density functional theory computations support a mechanism in which the dimerization is initiated by a [2 + 1] photocycloaddition favoured by the nature of carbon-carbon short contacts in the crystal structure. The reaction proceeded up to the theoretical degree of conversion without loss of crystallinity, and it was also performed on a preparative scale with good yield. Moreover, it represents the first synthetic pathway to (E)-1,2-dibromo-1,2-diethynylethenes, which could serve as synthetic intermediates for the preparation of molecular carbon scaffolds. Our findings both extend the scope of single-crystal-to-single-crystal reactions and highlight their potential as a synthetic tool for complex transformations.

  7. Protein determination in single corns

    International Nuclear Information System (INIS)

    Knorr, J.; Schiekel, M.; Franke, W.; Focke, F.

    1994-01-01

    Determination of protein content in food materials is usually done by analyzing the nitrogen amount by wet chemical Kjeldahl method. An improved accuracy accompanied by smaller analyzing intervals can be achieved using nondestructive neutron activation. Analyses have been performed using 14 MeV neutrons to determine the content of N and P in single wheat corns. Irradiation parameters have been optimized to prevent serious radiation damage in grains. About 200 single corns have been investigated with total net weights ranging from 30 to 70 mg. The tested arrangement allows determination of nitrogen amount in a single corn down to 0.3 mg with an accuracy of better than 4 %. Mean nitrogen concentrations in the range from 9 to 19% per corn have been detected. (author) 5 refs.; 6 figs

  8. Delivery of single accelerated particles

    International Nuclear Information System (INIS)

    McNulty, P.J.; Pease, V.P.; Bond, V.P.; Schimmerling, W.; Vosburgh, K.G.; Crebbin, K.; Everette, W.; Howard, J.

    1978-01-01

    It is desirable for certain experiments involving accelerators to have the capability of delivering just a single beam particle to the target area. The essential features of such a one-at-a-time facility are discussed. Two such facilities are described which were implemented at high-energy heavy ion accelerators without having to make major structural changes in the existing beam lines or substantially interfering with other accelerator uses. Two accelerator facilities are described which had the capability of delivering a single beam particle to the target area. This feature is necessary in certain experiments investigating visual phenomena induced by charged particles, other single particle interactions in biology, and other experiments in which the low intensities of cosmic rays need to be simulated. Both facilities were implemented without having to make structural changes in the existing beam lines or substantially interfering with other accelerator uses. (Auth.)

  9. Single-electron charging effects

    International Nuclear Information System (INIS)

    Ruggiero, S.T.

    1991-01-01

    The status of our project on single-electron tunneling is, again, excellent. As outlined in our original proposal, a key goal in the development of this project was the demonstration and exploration of the microwave properties of single-electron system. As discussed in this paper such work has to data been carried out. Also as discussed in our previous progress report, the next step in the experimental evolution of the project will be to use lithographically-defined small dots as capacitors as outlined in our proposal. At this point we have made such microdotsdots as will be discussed. We have also continued our work with metal droplets to form single-electron tunnel systems

  10. Single-photon decision maker

    Science.gov (United States)

    Naruse, Makoto; Berthel, Martin; Drezet, Aurélien; Huant, Serge; Aono, Masashi; Hori, Hirokazu; Kim, Song-Ju

    2015-08-01

    Decision making is critical in our daily lives and for society in general and is finding evermore practical applications in information and communication technologies. Herein, we demonstrate experimentally that single photons can be used to make decisions in uncertain, dynamically changing environments. Using a nitrogen-vacancy in a nanodiamond as a single-photon source, we demonstrate the decision-making capability by solving the multi-armed bandit problem. This capability is directly and immediately associated with single-photon detection in the proposed architecture, leading to adequate and adaptive autonomous decision making. This study makes it possible to create systems that benefit from the quantum nature of light to perform practical and vital intelligent functions.

  11. Health Insurance without Single Crossing

    DEFF Research Database (Denmark)

    Boone, Jan; Schottmüller, Christoph

    2017-01-01

    Standard insurance models predict that people with high risks have high insurance coverage. It is empirically documented that people with high income have lower health risks and are better insured. We show that income differences between risk types lead to a violation of single crossing...... in an insurance model where people choose treatment intensity. We analyse different market structures and show the following: If insurers have market power, the violation of single crossing caused by income differences and endogenous treatment choice can explain the empirically observed outcome. Our results do...

  12. Single Cell Isolation and Analysis

    Directory of Open Access Journals (Sweden)

    Ping Hu

    2016-10-01

    Full Text Available Increasing evidence shows that the heterogeneity of individual cells within a genetically identical population can be critical to their peculiar function and fate. Conventional cell based assays mainly analysis the average responses from a population cells, while the difference within individual cells may often be masked. The cell size, RNA transcripts and protein expression level are quite different within individual cells and these variations are key point to answer the problems in cancer, neurobiology, stem cell biology, immunology and developmental biology. To better understand the cell-to-cell variations, the single cell analysis can provide much more detailed information which may be helpful for therapeutic decisions in an increasingly personalized medicine. In this review, we will focus on the recent development in single cell analysis, including methods used in single cell isolation, analysis and some application examples. The review provides the historical background to single cell analysis, discusses limitations, and current and future possibilities in this exciting field of research.

  13. Small angle single arm spectrometer

    International Nuclear Information System (INIS)

    Chien, C.Y.

    1976-01-01

    A study is given of an experiment described in the 1975 Summer Study to review the adequacy of the apparatus for its physics goals, equipment needs, logistic needs, vacuum chambers, compatibility with other experiments and to summarize its impacts on ISABELLE. The spectrometer is designed to study single particle inclusive spectra near x = 1 with particle identification and good momentum resolution

  14. Single-electron charging effects

    International Nuclear Information System (INIS)

    Ruggiero, S.T.

    1991-01-01

    The status of our project on single-electron tunneling is, again, excellent. As outlined in our original proposal, a key goal for this project has been the development of a scanning tunneling instrument for the purpose of imaging individual particles and tunneling into these particles at high magnetic fields. Further progress is discussed in this report

  15. Single liner shipping service design

    DEFF Research Database (Denmark)

    Plum, Christian Edinger Munk; Pisinger, David; Salazar-González, Juan-José

    2014-01-01

    The design of container shipping networks is an important logistics problem, involving assets and operational costs measured in billions of dollars. To guide the optimal deployment of the ships, a single vessel round trip is considered by minimizing operational costs and flowing the best paying...

  16. Single port Billroth I gastrectomy

    Directory of Open Access Journals (Sweden)

    Jeremy R Huddy

    2013-01-01

    Full Text Available Introduction: Experience has allowed increasingly complex procedures to be undertaken by single port surgery. We describe a technique for single port Billroth I gastrectomy with a hand-sewn intracorporeal anastomosis in the resection of a benign tumour diagnosed incidentally on a background of cholelithiasis. Materials and Methods: Single port Billroth I gastrectomy and cholecystectomy was performed using a transumbilical quadport. Flexible tipped camera and straight conventional instruments were used throughout the procedure. The stomach was mobilised including a limited lymph node dissection and resection margins in the proximal antrum and duodenum were divided with a flexible tipped laparoscopic stapler. The lesser curve was reconstructed and an intracorporal hand sewn two layer end-to-end anastomosis was performed using unidirectional barbed sutures. Intraoperative endoscopy confirmed the anastomosis to be patent without leak. Results: Enteral feed was started on the day of surgery, increasing to a full diet by day 6. Analgesic requirements were a patient-controlled analgesia morphine pump for 4 postoperative days and paracetamol for 6 days. There were no postoperative complications and the patient was discharged on the eighth day. Histology confirmed gastric submucosal lipoma. Discussion: As technology improves more complex procedures are possible by single port laparoscopic surgery. In this case, flexible tipped cameras and unidirectional barbed sutures have facilitated an intracorporal hand-sewn two layer end-to-end anastomosis. Experience will allow such techniques to become mainstream.

  17. Single-mode optical fibres

    CERN Document Server

    Cancellieri, G

    1991-01-01

    This book describes signal propagation in single-mode optical fibres for telecommunication applications. Such description is based on the analysis of field propagation, considering waveguide properties and also some of the particular characteristics of the material fibre. The book covers such recent advances as, coherent transmissions; optical amplification; MIR fibres; polarization maintaining; polarization diversity and photon counting.

  18. CERN single sign on solution

    International Nuclear Information System (INIS)

    Ormancey, E

    2008-01-01

    The need for Single Sign On has always been restricted by the absence of cross platform solutions: a single sign on working only on one platform or technology is nearly useless. The recent improvements in Web Services Federation (WS-Federation) standard enabling federation of identity, attribute, authentication and authorization information can now provide real extended Single Sign On solutions. Various solutions have been investigated at CERN and now, a Web SSO solution using some parts of WS-Federation technology is available. Using the Shibboleth Service Provider module for Apache hosted web sites and Microsoft ADFS as the identity provider linked to Active Directory user, users can now authenticate on any web application using a single authentication platform, providing identity, user information (building, phone...) as well as group membership enabling authorization possibilities. A typical scenario: a CERN user can now authenticate on a Linux/Apache website using Windows Integrated credentials, and his Active Directory group membership can be checked before allowing access to a specific web page

  19. Single particle distributions, ch.2

    International Nuclear Information System (INIS)

    Blokzijl, R.

    1977-01-01

    A survey of inclusive single particle distributions is given for various particles. A comparison of particle cross-sections measured in K - p experiments at different center of mass energies shows that some of these cross-sections remain almost constant over a wide range of incoming K - momenta

  20. Prospects of Single Tax Payers

    Directory of Open Access Journals (Sweden)

    Tofan Ivan M.

    2014-03-01

    Full Text Available The article speaks about problem aspects of taxation, which were set by the state for the single tax administering due to permanent and system changes in the tax legislation. It shows the necessity of search for alternative methods of administering in the process of taxation of single tax payers by fiscal services. The goal of the article is the study of prospects of further taxation of entrepreneurs – single tax payers on the basis of analysis of conditions and principles created by the state for the business. The article used methods of system analysis, comparison, forecasting and modelling. It analyses the process of evolution of the simplified taxation system, accounting and reporting from the moment of its adoption until today. The article presents the structure of the quantitative composition of single tax payers depending on the selected groups. It marks out and characterises administrative and fiscal factors that do not facilitate further development of entrepreneurship in Ukraine. In the result of the conducted studies the article outlines problem aspects of organisation of taxation of the small business and offers specific and real ways of their overcoming or partial solution.

  1. Single-Pilot Workload Management

    Science.gov (United States)

    Rogers, Jason; Williams, Kevin; Hackworth, Carla; Burian, Barbara; Pruchnicki, Shawn; Christopher, Bonny; Drechsler, Gena; Silverman, Evan; Runnels, Barry; Mead, Andy

    2013-01-01

    Integrated glass cockpit systems place a heavy cognitive load on pilots (Burian Dismukes, 2007). Researchers from the NASA Ames Flight Cognition Lab and the FAA Flight Deck Human Factors Lab examined task and workload management by single pilots. This poster describes pilot performance regarding programming a reroute while at cruise and meeting a waypoint crossing restriction on the initial descent.

  2. Single and Coupled Nanobeam Cavities

    DEFF Research Database (Denmark)

    Ivinskaya, Aliaksandra; Lavrinenko, Andrei; Shyroki, Dzmitry M.

    2013-01-01

    for analysis and design of photonic crystal devices, such as 2D ring resonators for filters, single and coupled nanobeam cavities, birefringence in photonic crystal cavities, threshold analysis in photonic crystal lasers, gap solitons in photonic crystals, novel photonic atolls, dynamic characteristics...

  3. A Single-Pulse Integrator

    DEFF Research Database (Denmark)

    Miller, Arne

    1974-01-01

    A single-pulse integrator is described. It gives a relative measure of the integral of the output signal from a coil monitor on the Risø 10 MeV linear accelerator, and displays the value on a digital voltmeter. The reproduccibility is found to be better than ±1% for an accelerated pulse charge...

  4. Single photon searches at PEP

    Energy Technology Data Exchange (ETDEWEB)

    Hollebeek, R.

    1985-12-01

    The MAC and ASP searches for events with a single photon and no other observed particles are reviewed. New results on the number of neutrino generations and limits on selection, photino, squark and gluino masses from the ASP experiment are presented.

  5. Single photon searches at PEP

    International Nuclear Information System (INIS)

    Hollebeek, R.

    1985-12-01

    The MAC and ASP searches for events with a single photon and no other observed particles are reviewed. New results on the number of neutrino generations and limits on selection, photino, squark and gluino masses from the ASP experiment are presented

  6. From joint to single audits

    DEFF Research Database (Denmark)

    Holm, Claus; Thinggaard, Frank

    2018-01-01

    This study analyses audit quality differences between audits by a single big audit firm and joint audits with either one or two big audit firms. We exploit the unique situation in Denmark beginning on 1 January 2005, at which time a long-standing mandatory joint audit system for listed companies ...

  7. Single molecules and single nanoparticles as windows to the nanoscale

    Science.gov (United States)

    Caldarola, Martín; Orrit, Michel

    2018-05-01

    Since the first optical detection of single molecules, they have been used as nanometersized optical sensors to explore the physical properties of materials and light-matter interaction at the nanoscale. Understanding nanoscale properties of materials is fundamental for the development of new technology that requires precise control of atoms and molecules when the quantum nature of matter cannot be ignored. In the following lines, we illustrate this journey into nanoscience with some experiments from our group.

  8. Mobile phone radiofrequency exposure has no effect on DNA double strand breaks (DSB) in human lymphocytes.

    Science.gov (United States)

    Danese, Elisa; Lippi, Giuseppe; Buonocore, Ruggero; Benati, Marco; Bovo, Chiara; Bonaguri, Chiara; Salvagno, Gian Luca; Brocco, Giorgio; Roggenbuck, Dirk; Montagnana, Martina

    2017-07-01

    The use of mobile phones has been associated with an increased risk of developing certain type of cancer, especially in long term users. Therefore, this study was aimed to investigate the potential genotoxic effect of mobile phone radiofrequency exposure on human peripheral blood mononuclear cells in vitro. The study population consisted in 14 healthy volunteers. After collection of two whole blood samples, the former was placed in a plastic rack, 1 cm from the chassis of a commercial mobile phone (900 MHz carrier frequency), which was activated by a 30-min call. The second blood sample was instead maintained far from mobile phones or other RF sources. The influence of mobile phone RF on DNA integrity was assessed by analyzing γ-H2AX foci in lymphocytes using immunofluorescence staining kit on AKLIDES. No measure of γ-H2AX foci was significantly influenced by mobile phone RF exposure, nor mobile phone exposure was associated with significant risk of genetic damages in vitro (odds ratio comprised between 0.27 and 1.00). The results of this experimental study demonstrate that exposure of human lymphocytes to a conventional 900 MHz RF emitted by a commercial mobile phone for 30 min does not significantly impact DNA integrity.

  9. Applied Railway Optimization in Production Planning at DSB-S-tog - Tasks, Tools and Challenges

    DEFF Research Database (Denmark)

    Clausen, Jens

    2007-01-01

    these conflicting goals. S-tog has therefore on the strategic level decided to use software with optimization capabilities in the planning processes. We describe the current status for each activity using optimization or simulation as a tool: Timetable evaluation, rolling stock planning, and crew scheduling...... to the customers, and has concurrently been met with demands for higher efficiency in the daily operation. The plans of timetable, rolling stock and crew must hence allow for a high level of customer service, be efficient, and be robust against disturbances of operations. It is a highly non-trivial task to meet....... In addition we describe on-going efforts in using mathematical models in activities such as timetable design and work-force planning. We also identify some organizatorial key factors, which have paved the way for extended use of optimization methods in railway production planning....

  10. Cluster analysis for the probability of DSB site induced by electron tracks

    Energy Technology Data Exchange (ETDEWEB)

    Yoshii, Y. [Biological Research, Education and Instrumentation Center, Sapporo Medical University, Sapporo 060-8556 (Japan); Graduate School of Health Sciences, Hokkaido University, Sapporo 060-0812 (Japan); Sasaki, K. [Faculty of Health Sciences, Hokkaido University of Science, Sapporo 006-8585 (Japan); Matsuya, Y. [Graduate School of Health Sciences, Hokkaido University, Sapporo 060-0812 (Japan); Date, H., E-mail: date@hs.hokudai.ac.jp [Faculty of Health Sciences, Hokkaido University, Sapporo 060-0812 (Japan)

    2015-05-01

    To clarify the influence of bio-cells exposed to ionizing radiations, the densely populated pattern of the ionization in the cell nucleus is of importance because it governs the extent of DNA damage which may lead to cell lethality. In this study, we have conducted a cluster analysis of ionization and excitation events to estimate the number of double-strand breaks (DSBs) induced by electron tracks. A Monte Carlo simulation for electrons in liquid water was performed to determine the spatial location of the ionization and excitation events. The events were divided into clusters by using the density-based spatial clustering of applications with noise (DBSCAN) algorithm. The algorithm enables us to sort out the events into the groups (clusters) in which a minimum number of neighboring events are contained within a given radius. For evaluating the number of DSBs in the extracted clusters, we have introduced an aggregation index (AI). The computational results show that a sub-keV electron produces DSBs in a dense formation more effectively than higher energy electrons. The root-mean square radius (RMSR) of the cluster size is below 5 nm, which is smaller than the chromatin fiber thickness. It was found that this size of clustering events has a high possibility to cause lesions in DNA within the chromatin fiber site.

  11. Chromosome aberration model combining radiation tracks, chromatin structure, DSB repair and chromatin mobility

    International Nuclear Information System (INIS)

    Friedland, W.; Kundrat, P.

    2015-01-01

    The module that simulates the kinetics and yields of radiation-induced chromosome aberrations within the biophysical code PARTRAC is described. Radiation track structures simulated by Monte Carlo methods are overlapped with multi-scale models of DNA and chromatin to assess the resulting DNA damage. Spatial mobility of individual DNA ends from double-strand breaks is modelled simultaneously with their processing by the non-homologous end-joining enzymes. To score diverse types of chromosome aberrations, the joined ends are classified regarding their original chromosomal location, orientation and the involvement of centromeres. A comparison with experimental data on dicentrics induced by gamma and alpha particles shows that their relative dose dependence is predicted correctly, although the absolute yields are overestimated. The critical model assumptions on chromatin mobility and on the initial damage recognition and chromatin remodelling steps and their future refinements to solve this issue are discussed. (authors)

  12. Single wire drift chamber design

    International Nuclear Information System (INIS)

    Krider, J.

    1987-01-01

    This report summarizes the design and prototype tests of single wire drift chambers to be used in Fermilab test beam lines. The goal is to build simple, reliable detectors which require a minimum of electronics. Spatial resolution should match the 300 μm rms resolution of the 1 mm proportional chambers that they will replace. The detectors will be used in beams with particle rates up to 20 KHz. Single track efficiency should be at least 99%. The first application will be in the MT beamline, which has been designed for calibration of CDF detectors. A set of four x-y modules will be used to track and measure the momentum of beam particles

  13. Invariance for Single Curved Manifold

    KAUST Repository

    Castro, Pedro Machado Manhaes de

    2012-01-01

    Recently, it has been shown that, for Lambert illumination model, solely scenes composed by developable objects with a very particular albedo distribution produce an (2D) image with isolines that are (almost) invariant to light direction change. In this work, we provide and investigate a more general framework, and we show that, in general, the requirement for such in variances is quite strong, and is related to the differential geometry of the objects. More precisely, it is proved that single curved manifolds, i.e., manifolds such that at each point there is at most one principal curvature direction, produce invariant is surfaces for a certain relevant family of energy functions. In the three-dimensional case, the associated energy function corresponds to the classical Lambert illumination model with albedo. This result is also extended for finite-dimensional scenes composed by single curved objects. © 2012 IEEE.

  14. Invariance for Single Curved Manifold

    KAUST Repository

    Castro, Pedro Machado Manhaes de

    2012-08-01

    Recently, it has been shown that, for Lambert illumination model, solely scenes composed by developable objects with a very particular albedo distribution produce an (2D) image with isolines that are (almost) invariant to light direction change. In this work, we provide and investigate a more general framework, and we show that, in general, the requirement for such in variances is quite strong, and is related to the differential geometry of the objects. More precisely, it is proved that single curved manifolds, i.e., manifolds such that at each point there is at most one principal curvature direction, produce invariant is surfaces for a certain relevant family of energy functions. In the three-dimensional case, the associated energy function corresponds to the classical Lambert illumination model with albedo. This result is also extended for finite-dimensional scenes composed by single curved objects. © 2012 IEEE.

  15. Theoretical Investigations Regarding Single Molecules

    DEFF Research Database (Denmark)

    Pedersen, Kim Georg Lind

    Neoclassical Valence Bond Theory, Quantum Transport, Quantum Interference, Kondo Effect, and Electron Pumping. Trap a single organic molecule between two electrodes and apply a bias voltage across this "molecular junction". When electrons pass through the molecule, the different electron paths can...... interfere destructively or constructively. Destructive interference effects in electron transport could potentially improve thermo-electrics, organic logic circuits and energy harvesting. We have investigated destructive interference in off-resonant transport through organic molecules, and have found a set...

  16. Single lens laser beam shaper

    Science.gov (United States)

    Liu, Chuyu [Newport News, VA; Zhang, Shukui [Yorktown, VA

    2011-10-04

    A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.

  17. The evolution of single stars

    International Nuclear Information System (INIS)

    Tayler, R.J.

    1982-01-01

    The general outline of the evolution of single stars is well understood but at most stages of evolution important uncertainties remain. This paper contains a very personal view of what are the major uncertainties and of what problems remain to be solved before one can be satisfied with the theory. It is suggested that some problems may be essentially insoluble even with the very large and fast computers that are currently available. (author)

  18. Single Nanowire Probe for Single Cell Endoscopy and Sensing

    Science.gov (United States)

    Yan, Ruoxue

    The ability to manipulate light in subwavelength photonic and plasmonic structures has shown great potentials in revolutionizing how information is generated, transformed and processed. Chemically synthesized nanowires, in particular, offers a unique toolbox not only for highly compact and integrated photonic modules and devices, including coherent and incoherent light sources, waveguides, photodetectors and photovoltaics, but also for new types of nanoscopic bio-probes for spot cargo delivery and in-situ single cell endoscopy and sensing. Such nanowire probes would enable us to carry out intracellular imaging and probing with high spatial resolution, monitor in-vivo biological processes within single living cells and greatly improve our fundamental understanding of cell functions, intracellular physiological processes, and cellular signal pathways. My work is aimed at developing a material and instrumental platform for such single nanowire probe. Successful optical integration of Ag nanowire plasmonic waveguides, which offers deep subwavelength mode confinement, and conventional photonic waveguides was demonstrated on a single nanowire level. The highest plasmonic-photonic coupling efficiency coupling was found at small coupling angles and low input frequencies. The frequency dependent propagation loss was observed in Ag nanowire and was confirmed by quantitative measurement and in agreement with theoretical expectations. Rational integration of dielectric and Ag nanowire waveguide components into hybrid optical-plasmonic routing devices has been demonstrated. This capability is essential for incorporating sub-100nm Ag nanowire waveguides into optical fiber based nanoprobes for single cell endoscopy. The nanoprobe system based on single nanowire waveguides was demonstrated by optically coupling semiconductor or metal nanowire with an optical fiber with tapered tip. This nanoprobe design requires minimal instrumentation which makes it cost efficient and readily

  19. Alternate Double Single Track Lines

    Energy Technology Data Exchange (ETDEWEB)

    Moraga Contreras, P.; Grande Andrade, Z.; Castillo Ron, E.

    2016-07-01

    The paper discusses the advantages and shortcomings of alternate double single track (ADST) lines with respect to double track lines for high speed lines. ADST lines consists of sequences of double and single track segments optimally selected in order to reduce the construction and maintenance costs of railway lines and to optimize the timetables used to satisfy a given demand. The single tracks are selected to coincide with expensive segments (tunnels and viaducts) and the double tracks are chosen to coincide with flat areas and only where they are necessary. At the same time, departure times are adjusted for trains to cross at the cheap double track segments. This alternative can be used for new lines and also for existing conventional lines where some new tracks are to be constructed to reduce travel time (increase speed). The ADST proposal is illustrated with some examples of both types (new lines and where conventional lines exist), including the Palencia-Santander, the Santiago-Valparaíso-Viña del Mar and the Dublin-Belfast lines, where very important reductions (90 %) are obtained, especially where a railway infrastructure already exist. (Author)

  20. Measuring single-cell density.

    Science.gov (United States)

    Grover, William H; Bryan, Andrea K; Diez-Silva, Monica; Suresh, Subra; Higgins, John M; Manalis, Scott R

    2011-07-05

    We have used a microfluidic mass sensor to measure the density of single living cells. By weighing each cell in two fluids of different densities, our technique measures the single-cell mass, volume, and density of approximately 500 cells per hour with a density precision of 0.001 g mL(-1). We observe that the intrinsic cell-to-cell variation in density is nearly 100-fold smaller than the mass or volume variation. As a result, we can measure changes in cell density indicative of cellular processes that would be otherwise undetectable by mass or volume measurements. Here, we demonstrate this with four examples: identifying Plasmodium falciparum malaria-infected erythrocytes in a culture, distinguishing transfused blood cells from a patient's own blood, identifying irreversibly sickled cells in a sickle cell patient, and identifying leukemia cells in the early stages of responding to a drug treatment. These demonstrations suggest that the ability to measure single-cell density will provide valuable insights into cell state for a wide range of biological processes.

  1. ON BIPOLAR SINGLE VALUED NEUTROSOPHIC GRAPHS

    OpenAIRE

    Said Broumi; Mohamed Talea; Assia Bakali; Florentin Smarandache

    2016-01-01

    In this article, we combine the concept of bipolar neutrosophic set and graph theory. We introduce the notions of bipolar single valued neutrosophic graphs, strong bipolar single valued neutrosophic graphs, complete bipolar single valued neutrosophic graphs, regular bipolar single valued neutrosophic graphs and investigate some of their related properties.

  2. Case Report: Emergency awake craniotomy for cerebral abscess in a patient with unrepaired cyanotic congenital heart disease [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Corinne D’Antico

    2016-10-01

    Full Text Available We report the case of a 39-year-old male with complex cyanotic congenital heart disease undergoing emergency craniotomy for a cerebral abscess. Maintenance of intraoperative hemodynamic stability and adequate tissue oxygenation during anesthesia may be challenging in patients with cyanotic congenital heart disease. In this case, we decided to perform the surgery as an awake craniotomy after interdisciplinary consensus. We discuss general aspects of anesthetic management during awake craniotomy and specific concerns in the perioperative care of patients with congenital heart disease.

  3. Case Report: Emergency awake craniotomy for cerebral abscess in a patient with unrepaired cyanotic congenital heart disease [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Corinne D’Antico

    2017-02-01

    Full Text Available We report the case of a 39-year-old male with complex cyanotic congenital heart disease undergoing emergency craniotomy for a cerebral abscess. Maintenance of intraoperative hemodynamic stability and adequate tissue oxygenation during anesthesia may be challenging in patients with cyanotic congenital heart disease. In this case, we decided to perform the surgery as an awake craniotomy after interdisciplinary consensus. We discuss general aspects of anesthetic management during awake craniotomy and specific concerns in the perioperative care of patients with congenital heart disease.

  4. Rats with a missense mutation in Atm display neuroinflammation and neurodegeneration subsequent to accumulation of cytosolic DNA following unrepaired DNA damage.

    Science.gov (United States)

    Quek, Hazel; Luff, John; Cheung, KaGeen; Kozlov, Sergei; Gatei, Magtouf; Lee, C Soon; Bellingham, Mark C; Noakes, Peter G; Lim, Yi Chieh; Barnett, Nigel L; Dingwall, Steven; Wolvetang, Ernst; Mashimo, Tomoji; Roberts, Tara L; Lavin, Martin F

    2017-04-01

    Mutations in the ataxia-telangiectasia (A-T)-mutated ( ATM ) gene give rise to the human genetic disorder A-T, characterized by immunodeficiency, cancer predisposition, and neurodegeneration. Whereas a series of animal models recapitulate much of the A-T phenotype, they fail to present with ataxia or neurodegeneration. We describe here the generation of an Atm missense mutant [amino acid change of leucine (L) to proline (P) at position 2262 (L2262P)] rat by intracytoplasmic injection (ICSI) of mutant sperm into oocytes. Atm -mutant rats ( Atm L2262P/L2262P ) expressed low levels of ATM protein, suggesting a destabilizing effect of the mutation, and had a significantly reduced lifespan compared with Atm +/+ Whereas these rats did not show cerebellar atrophy, they succumbed to hind-limb paralysis (45%), and the remainder developed tumors. Closer examination revealed the presence of both dsDNA and ssDNA in the cytoplasm of cells in the hippocampus, cerebellum, and spinal cord of Atm L2262P/L2262P rats. Significantly increased levels of IFN-β and IL-1β in all 3 tissues were indicative of DNA damage induction of the type 1 IFN response. This was further supported by NF-κB activation, as evidenced by p65 phosphorylation (P65) and translocation to the nucleus in the spinal cord and parahippocampus. Other evidence of neuroinflammation in the brain and spinal cord was the loss of motor neurons and the presence of increased activation of microglia. These data provide support for a proinflammatory phenotype that is manifested in the Atm mutant rat as hind-limb paralysis. This mutant represents a useful model to investigate the importance of neuroinflammation in A-T. © Society for Leukocyte Biology.

  5. Experimental techniques for single cell and single molecule biomechanics

    International Nuclear Information System (INIS)

    Lim, C.T.; Zhou, E.H.; Li, A.; Vedula, S.R.K.; Fu, H.X.

    2006-01-01

    Stresses and strains that act on the human body can arise either from external physical forces or internal physiological environmental conditions. These biophysical interactions can occur not only at the musculoskeletal but also cellular and molecular levels and can determine the health and function of the human body. Here, we seek to investigate the structure-property-function relationship of cells and biomolecules so as to understand their important physiological functions as well as establish possible connections to human diseases. With the recent advancements in cell and molecular biology, biophysics and nanotechnology, several innovative and state-of-the-art experimental techniques and equipment have been developed to probe the structural and mechanical properties of biostructures from the micro- down to picoscale. Some of these experimental techniques include the optical or laser trap method, micropipette aspiration, step-pressure technique, atomic force microscopy and molecular force spectroscopy. In this article, we will review the basic principles and usage of these techniques to conduct single cell and single molecule biomechanics research

  6. Single-edition quadrangle maps

    Science.gov (United States)

    ,

    1998-01-01

    In August 1993, the U.S. Geological Survey's (USGS) National Mapping Division and the U.S. Department of Agriculture's Forest Service signed an Interagency Agreement to begin a single-edition joint mapping program. This agreement established the coordination for producing and maintaining single-edition primary series topographic maps for quadrangles containing National Forest System lands. The joint mapping program saves money by eliminating duplication of effort by the agencies and results in a more frequent revision cycle for quadrangles containing national forests. Maps are revised on the basis of jointly developed standards and contain normal features mapped by the USGS, as well as additional features required for efficient management of National Forest System lands. Single-edition maps look slightly different but meet the content, accuracy, and quality criteria of other USGS products. The Forest Service is responsible for the land management of more than 191 million acres of land throughout the continental United States, Alaska, and Puerto Rico, including 155 national forests and 20 national grasslands. These areas make up the National Forest System lands and comprise more than 10,600 of the 56,000 primary series 7.5-minute quadrangle maps (15-minute in Alaska) covering the United States. The Forest Service has assumed responsibility for maintaining these maps, and the USGS remains responsible for printing and distributing them. Before the agreement, both agencies published similar maps of the same areas. The maps were used for different purposes, but had comparable types of features that were revised at different times. Now, the two products have been combined into one so that the revision cycle is stabilized and only one agency revises the maps, thus increasing the number of current maps available for National Forest System lands. This agreement has improved service to the public by requiring that the agencies share the same maps and that the maps meet a

  7. Patterning of Perovskite Single Crystals

    KAUST Repository

    Corzo, Daniel

    2017-06-12

    As the internet-of-things hardware integration continues to develop and the requirements for electronics keep diversifying and expanding, the necessity for specialized properties other than the classical semiconductor performance becomes apparent. The success of emerging semiconductor materials depends on the manufacturability and cost as much as on the properties and performance they offer. Solution-based semiconductors are an emerging concept that offers the advantage of being compatible with large-scale manufacturing techniques and have the potential to yield high-quality electronic devices at a lower cost than currently available solutions. In this work, patterns of high-quality MAPbBr3 perovskite single crystals in specific locations are achieved through the modification of the substrate properties and solvent engineering. The fabrication of the substrates involved modifying the surface adhesion forces through functionalization with self-assembled monolayers and patterning them by photolithography processes. Spin coating and blade coating were used to deposit the perovskite solution on the modified silicon substrates. While single crystal perovskites were obtained with the modification of substrates alone, solvent engineering helped with improving the Marangoni flows in the deposited droplets by increasing the contact angle and lowering the evaporation rate, therefore controlling and improving the shape of the grown perovskite crystals. The methodology is extended to other types of perovskites such as the transparent MAPbCl3 and the lead-free MABi2I9, demonstrating the adaptability of the process. Adapting the process to electrode arrays opened up the path towards the fabrication of optoelectronic devices including photodetectors and field-effect transistors, for which the first iterations are demonstrated. Overall, manufacturing and integration techniques permitting the fabrication of single crystalline devices, such as the method in this thesis work, are

  8. Investigation of single event latchup

    International Nuclear Information System (INIS)

    Xue Yuxiong; Yang Shengsheng; Cao Zhou; Ba Dedong; An Heng; Chen Luojing; Guo Gang

    2012-01-01

    Radiation effects on avionics microelectronics are important reliability issues for many space applications. In particular, single-event latchup (SEL) phenomenon is a major threat to CMOS integrated circuits in space systems. To effectively circumvent the failure, it is important to know the behavior of such devices during latchup. In this paper, the mechanisms for SEL in CMOS devices are investigated. Several microelectronic devices used in avionics are tested using heavy ion beams, pulsed laser and 252 Cf source. Based on the SEL test results, SEL-hardening and monitoring methods for preventing SEL from the systems design level are proposed. (authors)

  9. Single-cell photoacoustic thermometry

    Science.gov (United States)

    Gao, Liang; Wang, Lidai; Li, Chiye; Liu, Yan; Ke, Haixin; Zhang, Chi

    2013-01-01

    Abstract. A novel photoacoustic thermometric method is presented for simultaneously imaging cells and sensing their temperature. With three-seconds-per-frame imaging speed, a temperature resolution of 0.2°C was achieved in a photo-thermal cell heating experiment. Compared to other approaches, the photoacoustic thermometric method has the advantage of not requiring custom-developed temperature-sensitive biosensors. This feature should facilitate the conversion of single-cell thermometry into a routine lab tool and make it accessible to a much broader biological research community. PMID:23377004

  10. Single event upset test programs

    International Nuclear Information System (INIS)

    Russen, L.C.

    1984-11-01

    It has been shown that the heavy ions in cosmic rays can give rise to single event upsets in VLSI random access memory devices (RAMs). Details are given of the programs written to test 1K, 4K, 16K and 64K memories during their irradiation with heavy charged ions, in order to simulate the effects of cosmic rays in space. The test equipment, which is used to load the memory device to be tested with a known bit pattern, and subsequently interrogate it for upsets, or ''flips'', is fully described. (author)

  11. SINGLE HEATER TEST FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    J.B. Cho

    1999-05-01

    The Single Heater Test is the first of the in-situ thermal tests conducted by the U.S. Department of Energy as part of its program of characterizing Yucca Mountain in Nevada as the potential site for a proposed deep geologic repository for the disposal of spent nuclear fuel and high-level nuclear waste. The Site Characterization Plan (DOE 1988) contained an extensive plan of in-situ thermal tests aimed at understanding specific aspects of the response of the local rock-mass around the potential repository to the heat from the radioactive decay of the emplaced waste. With the refocusing of the Site Characterization Plan by the ''Civilian Radioactive Waste Management Program Plan'' (DOE 1994), a consolidated thermal testing program emerged by 1995 as documented in the reports ''In-Situ Thermal Testing Program Strategy'' (DOE 1995) and ''Updated In-Situ Thermal Testing Program Strategy'' (CRWMS M&O 1997a). The concept of the Single Heater Test took shape in the summer of 1995 and detailed planning and design of the test started with the beginning fiscal year 1996. The overall objective of the Single Heater Test was to gain an understanding of the coupled thermal, mechanical, hydrological, and chemical processes that are anticipated to occur in the local rock-mass in the potential repository as a result of heat from radioactive decay of the emplaced waste. This included making a priori predictions of the test results using existing models and subsequently refining or modifying the models, on the basis of comparative and interpretive analyses of the measurements and predictions. A second, no less important, objective was to try out, in a full-scale field setting, the various instruments and equipment to be employed in the future on a much larger, more complex, thermal test of longer duration, such as the Drift Scale Test. This ''shake down'' or trial aspect of the Single Heater Test applied

  12. SINGLE HEATER TEST FINAL REPORT

    International Nuclear Information System (INIS)

    J.B. Cho

    1999-01-01

    The Single Heater Test is the first of the in-situ thermal tests conducted by the U.S. Department of Energy as part of its program of characterizing Yucca Mountain in Nevada as the potential site for a proposed deep geologic repository for the disposal of spent nuclear fuel and high-level nuclear waste. The Site Characterization Plan (DOE 1988) contained an extensive plan of in-situ thermal tests aimed at understanding specific aspects of the response of the local rock-mass around the potential repository to the heat from the radioactive decay of the emplaced waste. With the refocusing of the Site Characterization Plan by the ''Civilian Radioactive Waste Management Program Plan'' (DOE 1994), a consolidated thermal testing program emerged by 1995 as documented in the reports ''In-Situ Thermal Testing Program Strategy'' (DOE 1995) and ''Updated In-Situ Thermal Testing Program Strategy'' (CRWMS M and O 1997a). The concept of the Single Heater Test took shape in the summer of 1995 and detailed planning and design of the test started with the beginning fiscal year 1996. The overall objective of the Single Heater Test was to gain an understanding of the coupled thermal, mechanical, hydrological, and chemical processes that are anticipated to occur in the local rock-mass in the potential repository as a result of heat from radioactive decay of the emplaced waste. This included making a priori predictions of the test results using existing models and subsequently refining or modifying the models, on the basis of comparative and interpretive analyses of the measurements and predictions. A second, no less important, objective was to try out, in a full-scale field setting, the various instruments and equipment to be employed in the future on a much larger, more complex, thermal test of longer duration, such as the Drift Scale Test. This ''shake down'' or trial aspect of the Single Heater Test applied not just to the hardware, but also to the teamwork and cooperation between

  13. Single wafer rapid thermal multiprocessing

    International Nuclear Information System (INIS)

    Saraswat, K.C.; Moslehi, M.M.; Grossman, D.D.; Wood, S.; Wright, P.; Booth, L.

    1989-01-01

    Future success in microelectronics will demand rapid innovation, rapid product introduction and ability to react to a change in technological and business climate quickly. These technological advances in integrated electronics will require development of flexible manufacturing technology for VLSI systems. However, the current approach of establishing factories for mass manufacturing of chips at a cost of more than 200 million dollars is detrimental to flexible manufacturing. The authors propose concepts of a micro factory which may be characterized by more economical small scale production, higher flexibility to accommodate many products on several processes, and faster turnaround and learning. In-situ multiprocessing equipment where several process steps can be done in sequence may be a key ingredient in this approach. For this environment to be flexible, the equipment must have ability to change processing environment, requiring extensive in-situ measurements and real time control. This paper describes the development of a novel single wafer rapid thermal multiprocessing (RTM) reactor for next generation flexible VLSI manufacturing. This reactor will combine lamp heating, remote microwave plasma and photo processing in a single cold-wall chamber, with applications for multilayer in-situ growth and deposition of dielectrics, semiconductors and metals

  14. Single-Molecule Stochastic Resonance

    Directory of Open Access Journals (Sweden)

    K. Hayashi

    2012-08-01

    Full Text Available Stochastic resonance (SR is a well-known phenomenon in dynamical systems. It consists of the amplification and optimization of the response of a system assisted by stochastic (random or probabilistic noise. Here we carry out the first experimental study of SR in single DNA hairpins which exhibit cooperatively transitions from folded to unfolded configurations under the action of an oscillating mechanical force applied with optical tweezers. By varying the frequency of the force oscillation, we investigate the folding and unfolding kinetics of DNA hairpins in a periodically driven bistable free-energy potential. We measure several SR quantifiers under varied conditions of the experimental setup such as trap stiffness and length of the molecular handles used for single-molecule manipulation. We find that a good quantifier of the SR is the signal-to-noise ratio (SNR of the spectral density of measured fluctuations in molecular extension of the DNA hairpins. The frequency dependence of the SNR exhibits a peak at a frequency value given by the resonance-matching condition. Finally, we carry out experiments on short hairpins that show how SR might be useful for enhancing the detection of conformational molecular transitions of low SNR.

  15. Laparoendoscopic single site surgery in urology: A single centre experience

    Directory of Open Access Journals (Sweden)

    Arvind P Ganpule

    2012-01-01

    Full Text Available Objective : To analyze our experience of 87 cases with single port surgery, which is also known as laparoendoscopic single site surgery (LESS. Materials and Methods: Case records of all LESS procedures performed between December 2007 and June 2010 were analysed. The procedures performed were donor nephrectomy (n=45, simple nephrectomy (n=27, radical nephrectomy (n=5, pyeloplasty (n=9, and ureteroneocystostomy (n=1. Parameters analysed were operating room (OR time, estimated blood loss (EBL, visual analogue score (VAS, and complications in all patients undergoing LESS procedure and additionally, warm ischaemia time (WIT and graft outcome in patients undergoing LESS donor nephrectomy. In reconstructive procedures, the functional assessment was performed with a diuretic renogram at 6 months. Results: In LESS donor nephrectomy, the mean WIT was 6.9 ± 1.9 min. Mean serum creatinine in recipients at 1 month was 0.96 ± 0.21 mg%. We encountered one instance each of renal artery injury, renal vein injury, large bowel injury, minor cortical laceration at the upper pole and two instances of diaphragmatic injury. In LESS simple nephrectomy, the average OR time was 148.7 ± 52.2 min and hospital stay was 3.7 ± 1.2 days. There was one instance of large bowel injury during specimen retrieval. In LESS radical nephrectomy, the average OR time was 202.5 ± 35.7 min and average hospital stay was 4.2 ± 1.3 days. 6 patients of LESS pyeloplasty completed follow up with a diuretic renogram showing a good drainage. LESS ureteroneocystostomy could also be performed successfully without any complications. Conclusion: LESS surgery can be accomplished safely in nephrectomy and reconstructive procedures such as pyeloplasty and ureteroneocystostomy with equivalent outcomes as standard laparoscopy and with added benefits of cosmesis and quicker convalescence. LESS donor nephrectomy is a technically feasible procedure; current status of procedure needs to be proved with

  16. Single bunch fast longitudinal instability

    International Nuclear Information System (INIS)

    Wang, J.M.; Pellegrini, C.

    1979-01-01

    Single bunch longitudinal instability producing an increase of the bunch area have been observed in proton synchrotron and storage rings. Signals at microwave frequencies are observed during the bunch blow-up and because of this the effect has been called the microwave instability. A similar increase in bunch area is observed also in electron storage rings, where it is usually referred to as the bunch lengthening effect. This paper is an attempt to obtain a more general theory of this effect. Here we describe the model used and the method of calculation, together with some general results. More detailed results will be given in another paper. The main result is the derivation of a condition for the existence of a fast longitudinal bunch blow-up. This condition is a generalized threshold formula, showing explicitly the dependence on the bunch energy spread and length. This condition is qualitatively in agreement with Boussard's suggestion

  17. Single-bunch kicker pulser

    International Nuclear Information System (INIS)

    Frey, W.W.

    1983-01-01

    The single-bunch kicker magnet is powered by a capacitor discharge pulser. The ferrite-core magnet is used to kick out one of twelve proton bunches circulating in the AGS (Alternating Gradient Synchrotron) into the experimental area. The magnet current pulse has a half-sinusoid shape, with a peak current of 2800 A. The pulse current rises and falls to zero, with minimum undershoot, in 410 nsec to minimize effects on adjacent bunches. The magnet inductance is 1.0 μHy. The pulser is mounted on the kicker magnet in the AGS ring, and is exposed to ionizing radiation. The HVDC power supply, controls, monitoring, and auxiliary circuits are housed approximately 300 feet away external to the ring. A two-gap thyratron is used to discharge the energy storage capacitor. Two hydrogen diodes are series connected to function as an inverse diode

  18. Single-bunch kicker pulser

    Energy Technology Data Exchange (ETDEWEB)

    Frey, W.W.

    1983-01-01

    The single-bunch kicker magnet is powered by a capacitor discharge pulser. The ferrite-core magnet is used to kick out one of twelve proton bunches circulating in the AGS (Alternating Gradient Synchrotron) into the experimental area. The magnet current pulse has a half-sinusoid shape, with a peak current of 2800 A. The pulse current rises and falls to zero, with minimum undershoot, in 410 nsec to minimize effects on adjacent bunches. The magnet inductance is 1.0 ..mu..Hy. The pulser is mounted on the kicker magnet in the AGS ring, and is exposed to ionizing radiation. The HVDC power supply, controls, monitoring, and auxiliary circuits are housed approximately 300 feet away external to the ring. A two-gap thyratron is used to discharge the energy storage capacitor. Two hydrogen diodes are series connected to function as an inverse diode.

  19. Single-contact tunneling thermometry

    Science.gov (United States)

    Maksymovych, Petro

    2016-02-23

    A single-contact tunneling thermometry circuit includes a tunnel junction formed between two objects. Junction temperature gradient information is determined based on a mathematical relationship between a target alternating voltage applied across the junction and the junction temperature gradient. Total voltage measured across the junction indicates the magnitude of the target alternating voltage. A thermal gradient is induced across the junction. A reference thermovoltage is measured when zero alternating voltage is applied across the junction. An increasing alternating voltage is applied while measuring a thermovoltage component and a DC rectification voltage component created by the applied alternating voltage. The target alternating voltage is reached when the thermovoltage is nullified or doubled by the DC rectification voltage depending on the sign of the reference thermovoltage. Thermoelectric current and current measurements may be utilized in place of the thermovoltage and voltage measurements. The system may be automated with a feedback loop.

  20. Single fatherhood due to cancer.

    Science.gov (United States)

    Yopp, Justin M; Rosenstein, Donald L

    2012-12-01

    Cancer is a leading cause of widowed fatherhood in the USA. Fathers whose spouses have died from cancer constitute a potentially vulnerable population as they adjust to their role as sole or primary caregiver while managing their own grief and that of their children. The importance of addressing the psychological needs of widowed fathers is underscored by data showing that father's coping and emotional availability are closely tied to their bereaved children's mental health. Surprisingly, scant attention has been given to the phenomenon of widowed fatherhood with virtually no clinical resources or research studies devoted to fathers who have lost their wives to cancer. This commentary highlights key challenges facing this underserved population of widowers and calls for development of research agendas and clinical interventions for single fathers due to cancer. Copyright © 2011 John Wiley & Sons, Ltd.

  1. Multiple single-centered attractors

    International Nuclear Information System (INIS)

    Dominic, Pramod; Mandal, Taniya; Tripathy, Prasanta K.

    2014-01-01

    In this paper we study spherically symmetric single-centered attractors in N=2 supergravity in four dimensions. The attractor points are obtained by extremising the effective black hole potential in the moduli space. Both supersymmetric as well as non-supersymmetric attractors exist in mutually exclusive domains of the charge lattice. We construct axion free supersymmetric as well as non-supersymmetric multiple attractors in a simple two parameter model. We further obtain explicit examples of two distinct non-supersymmetric attractors in type IIA string theory compactified on K3×T"2 carrying D0−D4−D6 charges. We compute the entropy of these attractors and analyse their stability in detail.

  2. Single photon emission computerized tomography

    International Nuclear Information System (INIS)

    Hooge, P. de.

    1983-01-01

    In this thesis two single-photon emission tomographic techniques are presented: (a) longitudinal tomography with a rotating slanting-hole collimator, and (b) transversal tomography with a rotating gamma camera. These methods overcome the disadvantages of conventional scintigraphy. Both detection systems and the image construction methods are explained and comparisons with conventional scintigraphy are drawn. One chapter is dedicated to the determination of system parameters like spatial resolution, contrast, detector uniformity, and size of the object, by phantom studies. In separate chapters the results are presented of detection of tumors and metastases in the liver and the liver hilus; skeletal diseases; various pathological aberrations of the brain; and myocardial perfusion. The possible use of these two ect's for other organs and body areas is discussed in the last chapter. (Auth.)

  3. Single bunch fast longitudinal instability

    International Nuclear Information System (INIS)

    Wang, J.M.; Pellegrini, C.

    1979-01-01

    Single bunch longitudinal instability producing an increase of the bunch areas has been observed in proton synchrotron and storage rings. Singals at microwave frequencies are observed during the bunch blow-up and because of this the effect has been called the microwave instability. A similar increase in bunch area is observed also in electron storage rings, where it is usually referred to as the bunch lengthening effect. This paper is an attempt to obtain a more general theory of this effect. Here we describe the model used and the method of calculation, together with some general results. The main result of this paper is the derivation of a condition for the existence of a fast longitudinal bunch blow-up. This condition is a generalized threshold formula, showing explicitly the dependence on the bunch energy spread and length

  4. Chemical Transfer (Single Small-Scale) Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Description/History: Chemistry laboratoryThe Chemical Transfer Facility (CTF)  is the only U.S. single small-scale  facility, a single repository for the Army’s...

  5. A component of DNA double-strand break repair is dependent on the spatial orientation of the lesions within the higher-order structures of chromatin

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, P.J.; Bryant, P.E. (Saint Andrews Univ. (United Kingdom))

    1994-11-01

    By the use of a modified neutral filter elution procedure variations in the repair of DNA dsb have been observed between the ionising radiation sensitive mutant xrs-5 and the parent cell line CHO-K1. Conventional neutral filter elution requires harsh lysis conditions to remove higher-order chromatin structures which interfere with elution of DNA containing dsb. By lysing cells with non-ionic detergent in the presence of 2 mol dm[sup -3] salt, histone-depleted structures that retain the higher-order nuclear matrix organization, including chromatin loops, can be produced. Elution from these structures will only occur if two or more dsb lie within a single-looped domain delineated by points of attachment to the nuclear matrix. Repair experiments indicate that in CHO cells repair of dsb in loops containing multiple dsb are repaired with slow kinetics whilst dsb occurring in loops containing single dsb are repaired with fast kinetics. Xrs-5 cells are defective in the repair of multiply damaged loops. This work indicates that the spatial orientation of dsb in the higher-order structures of chromatin are a possible factor in the repair of these lesions. (Author).

  6. A component of DNA double-strand break repair is dependent on the spatial orientation of the lesions within the higher-order structures of chromatin

    International Nuclear Information System (INIS)

    Johnston, P.J.; Bryant, P.E.

    1994-01-01

    By the use of a modified neutral filter elution procedure variations in the repair of DNA dsb have been observed between the ionising radiation sensitive mutant xrs-5 and the parent cell line CHO-K1. Conventional neutral filter elution requires harsh lysis conditions to remove higher-order chromatin structures which interfere with elution of DNA containing dsb. By lysing cells with non-ionic detergent in the presence of 2 mol dm -3 salt, histone-depleted structures that retain the higher-order nuclear matrix organization, including chromatin loops, can be produced. Elution from these structures will only occur if two or more dsb lie within a single-looped domain delineated by points of attachment to the nuclear matrix. Repair experiments indicate that in CHO cells repair of dsb in loops containing multiple dsb are repaired with slow kinetics whilst dsb occurring in loops containing single dsb are repaired with fast kinetics. Xrs-5 cells are defective in the repair of multiply damaged loops. This work indicates that the spatial orientation of dsb in the higher-order structures of chromatin are a possible factor in the repair of these lesions. (Author)

  7. The Promise of Single-Sex Classes

    Science.gov (United States)

    Stotsky, Sandra

    2012-01-01

    Despite the enthusiasm and the absence of definitive research on the pros and cons of single-sex classes, a 2011 article in Science, titled "The Pseudoscience of Single-Sex Schooling," by a new organization called American Council for CoEducational Schooling (ACCES) came out with the astonishing conclusion that single-sex education is…

  8. The Advantages of Single-Sex Education

    Science.gov (United States)

    Hughes, Teresa A.

    2006-01-01

    Traditionally, single-sex education has been provided in the form of private schooling. Title IX regulations have loosened as a result of the No Child Left Behind Legislation; therefore, public school districts now have the legal right to create single-sex classes or single-sex schools if they deem it to be in the best interest of their students.…

  9. Single chip camera active pixel sensor

    Science.gov (United States)

    Shaw, Timothy (Inventor); Pain, Bedabrata (Inventor); Olson, Brita (Inventor); Nixon, Robert H. (Inventor); Fossum, Eric R. (Inventor); Panicacci, Roger A. (Inventor); Mansoorian, Barmak (Inventor)

    2003-01-01

    A totally digital single chip camera includes communications to operate most of its structure in serial communication mode. The digital single chip camera include a D/A converter for converting an input digital word into an analog reference signal. The chip includes all of the necessary circuitry for operating the chip using a single pin.

  10. Single Subject Research: Applications to Special Education

    Science.gov (United States)

    Cakiroglu, Orhan

    2012-01-01

    Single subject research is a scientific research methodology that is increasingly used in the field of special education. Therefore, understanding the unique characteristics of single subject research methodology is critical both for educators and practitioners. Certain characteristics make single subject research one of the most preferred…

  11. Single-Parent Families in Rural Communities

    Science.gov (United States)

    Lewis, Ken

    1978-01-01

    Presenting national statistics on single-parent families, this article illustrates the need for serious study of this phenomenon, suggesting that changing divorce laws, increased single-parent adoptions, and an increase in the number of supportive services for single-parent families are contingencies having significant bearing upon the…

  12. Single Particle Entropy in Heated Nuclei

    International Nuclear Information System (INIS)

    Guttormsen, M.; Chankova, R.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Syed, N. U. H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.

    2006-01-01

    The thermal motion of single particles represents the largest contribution to level density (or entropy) in atomic nuclei. The concept of single particle entropy is presented and shown to be an approximate extensive (additive) quantity for mid-shell nuclei. A few applications of single particle entropy are demonstrated

  13. Depletion of the type 1 IGF receptor delays repair of radiation-induced DNA double strand breaks

    International Nuclear Information System (INIS)

    Turney, Benjamin W.; Kerr, Martin; Chitnis, Meenali M.; Lodhia, Kunal; Wang, Yong; Riedemann, Johann; Rochester, Mark; Protheroe, Andrew S.; Brewster, Simon F.; Macaulay, Valentine M.

    2012-01-01

    Background and purpose: IGF-1R depletion sensitizes prostate cancer cells to ionizing radiation and DNA-damaging cytotoxic drugs. This study investigated the hypothesis that IGF-1R regulates DNA double strand break (DSB) repair. Methods: We tested effects of IGF-1R siRNA transfection on the repair of radiation-induced DSBs by immunoblotting and immunofluorescence for γH2AX, and pulsed-field gel electrophoresis. Homologous recombination (HR) was quantified by reporter assays, and cell cycle distribution by flow cytometry. Results: We confirmed that IGF-1R depletion sensitized DU145 and PC3 prostate cancer cells to ionizing radiation. DU145 control transfectants resolved radiation-induced DSBs within 24 h, while IGF-1R depleted cells contained 30–40% unrepaired breaks at 24 h. IGF-1R depletion induced significant reduction in DSB repair by HR, although the magnitude of the repair defect suggests additional contributory factors. Radiation-induced G2-M arrest was attenuated by IGF-1R depletion, potentially suppressing cell cycle-dependent processes required for HR. In contrast, IGF-1R depletion induced only minor radiosensitization in LNCaP cells, and did not influence repair. Cell cycle profiles were similar to DU145, so were unlikely to account for differences in repair responses. Conclusions: These data indicate a role for IGF-1R in DSB repair, at least in part via HR, and support use of IGF-1R inhibitors with DNA damaging cancer treatments.

  14. Nitric oxide mediated DNA double strand breaks induced in proliferating bystander cells after {alpha}-particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Han Wei [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Chen Shaopeng [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Yu, K.N., E-mail: peter.yu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Wu Lijun [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2010-02-03

    Low-dose {alpha}-particle exposures comprise 55% of the environmental dose to the human population and have been shown to induce bystander responses. Previous studies showed that bystander effect could induce stimulated cell growth or genotoxicity, such as excessive DNA double strand breaks (DSBs), micronuclei (MN), mutation and decreased cell viability, in the bystander cell population. In the present study, the stimulated cell growth, detected with flow cytometry (FCM), and the increased MN and DSB, detected with p53 binding protein 1 (53BP1) immunofluorescence, were observed simultaneously in the bystander cell population, which were co-cultured with cells irradiated by low-dose {alpha}-particles (1-10 cGy) in a mixed system. Further studies indicated that nitric oxide (NO) and transforming growth factor {beta}1 (TGF-{beta}1) played very important roles in mediating cell proliferation and inducing MN and DSB in the bystander population through treatments with NO scavenger and TGF-{beta}1 antibody. Low-concentrations of NO, generated by spermidine, were proved to induce cell proliferation, DSB and MN simultaneously. The proliferation or shortened cell cycle in bystander cells gave them insufficient time to repair DSBs. The increased cell division might increase the probability of carcinogenesis in bystander cells since cell proliferation increased the probability of mutation from the mis-repaired or un-repaired DSBs.

  15. Nitric oxide mediated DNA double strand breaks induced in proliferating bystander cells after α-particle irradiation

    International Nuclear Information System (INIS)

    Han Wei; Chen Shaopeng; Yu, K.N.; Wu Lijun

    2010-01-01

    Low-dose α-particle exposures comprise 55% of the environmental dose to the human population and have been shown to induce bystander responses. Previous studies showed that bystander effect could induce stimulated cell growth or genotoxicity, such as excessive DNA double strand breaks (DSBs), micronuclei (MN), mutation and decreased cell viability, in the bystander cell population. In the present study, the stimulated cell growth, detected with flow cytometry (FCM), and the increased MN and DSB, detected with p53 binding protein 1 (53BP1) immunofluorescence, were observed simultaneously in the bystander cell population, which were co-cultured with cells irradiated by low-dose α-particles (1-10 cGy) in a mixed system. Further studies indicated that nitric oxide (NO) and transforming growth factor β1 (TGF-β1) played very important roles in mediating cell proliferation and inducing MN and DSB in the bystander population through treatments with NO scavenger and TGF-β1 antibody. Low-concentrations of NO, generated by spermidine, were proved to induce cell proliferation, DSB and MN simultaneously. The proliferation or shortened cell cycle in bystander cells gave them insufficient time to repair DSBs. The increased cell division might increase the probability of carcinogenesis in bystander cells since cell proliferation increased the probability of mutation from the mis-repaired or un-repaired DSBs.

  16. Depletion of the type 1 IGF receptor delays repair of radiation-induced DNA double strand breaks.

    Science.gov (United States)

    Turney, Benjamin W; Kerr, Martin; Chitnis, Meenali M; Lodhia, Kunal; Wang, Yong; Riedemann, Johann; Rochester, Mark; Protheroe, Andrew S; Brewster, Simon F; Macaulay, Valentine M

    2012-06-01

    IGF-1R depletion sensitizes prostate cancer cells to ionizing radiation and DNA-damaging cytotoxic drugs. This study investigated the hypothesis that IGF-1R regulates DNA double strand break (DSB) repair. We tested effects of IGF-1R siRNA transfection on the repair of radiation-induced DSBs by immunoblotting and immunofluorescence for γH2AX, and pulsed-field gel electrophoresis. Homologous recombination (HR) was quantified by reporter assays, and cell cycle distribution by flow cytometry. We confirmed that IGF-1R depletion sensitized DU145 and PC3 prostate cancer cells to ionizing radiation. DU145 control transfectants resolved radiation-induced DSBs within 24 h, while IGF-1R depleted cells contained 30-40% unrepaired breaks at 24 h. IGF-1R depletion induced significant reduction in DSB repair by HR, although the magnitude of the repair defect suggests additional contributory factors. Radiation-induced G2-M arrest was attenuated by IGF-1R depletion, potentially suppressing cell cycle-dependent processes required for HR. In contrast, IGF-1R depletion induced only minor radiosensitization in LNCaP cells, and did not influence repair. Cell cycle profiles were similar to DU145, so were unlikely to account for differences in repair responses. These data indicate a role for IGF-1R in DSB repair, at least in part via HR, and support use of IGF-1R inhibitors with DNA damaging cancer treatments. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  17. Autophosphorylation of DNA-PKCS regulates its dynamics at DNA double-strand breaks.

    Science.gov (United States)

    Uematsu, Naoya; Weterings, Eric; Yano, Ken-ichi; Morotomi-Yano, Keiko; Jakob, Burkhard; Taucher-Scholz, Gisela; Mari, Pierre-Olivier; van Gent, Dik C; Chen, Benjamin P C; Chen, David J

    2007-04-23

    The DNA-dependent protein kinase catalytic subunit (DNA-PK(CS)) plays an important role during the repair of DNA double-strand breaks (DSBs). It is recruited to DNA ends in the early stages of the nonhomologous end-joining (NHEJ) process, which mediates DSB repair. To study DNA-PK(CS) recruitment in vivo, we used a laser system to introduce DSBs in a specified region of the cell nucleus. We show that DNA-PK(CS) accumulates at DSB sites in a Ku80-dependent manner, and that neither the kinase activity nor the phosphorylation status of DNA-PK(CS) influences its initial accumulation. However, impairment of both of these functions results in deficient DSB repair and the maintained presence of DNA-PK(CS) at unrepaired DSBs. The use of photobleaching techniques allowed us to determine that the kinase activity and phosphorylation status of DNA-PK(CS) influence the stability of its binding to DNA ends. We suggest a model in which DNA-PK(CS) phosphorylation/autophosphorylation facilitates NHEJ by destabilizing the interaction of DNA-PK(CS) with the DNA ends.

  18. Single conversion stage amplifier - SICAM

    Energy Technology Data Exchange (ETDEWEB)

    Ljusev, P.

    2005-12-15

    This Ph.D. thesis presents a thorough analysis of the so called SICAM - SIngle Converter stage AMplifier approach to building direct energy conversion audio power amplifiers. The mainstream approach for building isolated audio power amplifiers today consists of isolated DC power supply and Class D amplifier, which essentially represents a two stage solution, where each of the components can be viewed as separate and independent part. The proposed SICAM solution strives for direct energy conversion from the mains to the audio output, by dedicating the operation of the components one to another and integrating their functions, so that the final audio power amplifier represents a single-stage topology with higher efficiency, lower volume, less board space, lower component count and subsequently lower cost. The SICAM approach is both applicable to non-isolated and isolated audio power amplifiers, but the problems encountered in these two cases are different. Non-isolated SICAM solutions are intended for both AC mains-connected and battery-powered devices. In non-isolated mains-connected SICAMs the main idea is to simplify the power supply or even provide integrated power factor correction (PFC) functions, while still maintaining low component stress and good audio performance by generally decreasing the input voltage level to the Class D audio power amplifier. On the other hand, non-isolated battery-powered SICAMs have to cope with the ever changing battery voltage and provide output voltage levels which are both lower and higher than the battery voltage, while still being simple and single-stage energy conversion solutions. In isolated SICAMs the isolation transformer adjusts the voltage level on the secondary side to the desired level, so the main challenges here are decreasing the size of the magnetic core and reducing the number and size of bulky reactive components as much as possible. The main focus of this thesis is directed towards the isolated SICAMs and

  19. Relative contribution of homologous recombination and non-homologous end-joining to DNA double-strand break repair after oxidative stress in Saccharomyces cerevisiae.

    Science.gov (United States)

    Letavayová, Lucia; Marková, Eva; Hermanská, Katarína; Vlcková, Viera; Vlasáková, Danusa; Chovanec, Miroslav; Brozmanová, Jela

    2006-05-10

    Oxidative damage to DNA seems to be an important factor in developing many human diseases including cancer. It involves base and sugar damage, base-free sites, DNA-protein cross-links and DNA single-strand (SSB) and double-strand (DSB) breaks. Oxidative DSB can be formed in various ways such as their direct induction by the drug or their generation either through attempted and aborted repair of primary DNA lesions or through DNA replication-dependent conversion of SSB. In general, two main pathways are responsible for repairing DSB, homologous recombination (HR) and non-homologous end-joining (NHEJ), with both of them being potential candidates for the repair of oxidative DSB. We have examined relative contribution of HR and NHEJ to cellular response after oxidative stress in Saccharomyces cerevisiae. Therefore, cell survival, mutagenesis and DSB induction and repair in the rad52, yku70 and rad52 yku70 mutants after hydrogen peroxide (H(2)O(2)), menadione (MD) or bleomycin (BLM) exposure were compared to those obtained for the corresponding wild type. We show that MD exposure does not lead to observable DSB induction in yeast, suggesting that the toxic effects of this agent are mediated by other types of DNA damage. Although H(2)O(2) treatment generates some DSB, their yield is relatively low and hence DSB may only partially be responsible for toxicity of H(2)O(2), particularly at high doses of the agent. On the other hand, the basis of the BLM toxicity resides primarily in DSB induction. Both HR and NHEJ act on BLM-induced DSB, although their relative participation in the process is not equal. Based on our results we suggest that the complexity and/or the quality of the BLM-induced DSB might represent an obstacle for the NHEJ pathway.

  20. SEPIA - a new single pixel receiver at the APEX telescope

    Science.gov (United States)

    Belitsky, V.; Lapkin, I.; Fredrixon, M.; Meledin, D.; Sundin, E.; Billade, B.; Ferm, S.-E.; Pavolotsky, A.; Rashid, H.; Strandberg, M.; Desmaris, V.; Ermakov, A.; Krause, S.; Olberg, M.; Aghdam, P.; Shafiee, S.; Bergman, P.; Beck, E. De; Olofsson, H.; Conway, J.; Breuck, C. De; Immer, K.; Yagoubov, P.; Montenegro-Montes, F. M.; Torstensson, K.; Pérez-Beaupuits, J.-P.; Klein, T.; Boland, W.; Baryshev, A. M.; Hesper, R.; Barkhof, J.; Adema, J.; Bekema, M. E.; Koops, A.

    2018-04-01

    Context. We describe the new Swedish-ESO PI Instrument for APEX (SEPIA) receiver, which was designed and built by the Group for Advanced Receiver Development (GARD), at Onsala Space Observatory (OSO) in collaboration with ESO. It was installed and commissioned at the APEX telescope during 2015 with an ALMA Band 5 receiver channel and updated with a new frequency channel (ALMA Band 9) in February 2016. Aim. This manuscript aims to provide, for observers who use the SEPIA receiver, a reference in terms of the hardware description, optics and performance as well as the commissioning results. Methods: Out of three available receiver cartridge positions in SEPIA, the two current frequency channels, corresponding to ALMA Band 5, the RF band 158-211 GHz, and Band 9, the RF band 600-722 GHz, provide state-of-the-art dual polarization receivers. The Band 5 frequency channel uses 2SB SIS mixers with an average SSB noise temperature around 45 K with IF (intermediate frequency) band 4-8 GHz for each sideband providing total 4 × 4 GHz IF band. The Band 9 frequency channel uses DSB SIS mixers with a noise temperature of 75-125 K with IF band 4-12 GHz for each polarization. Results: Both current SEPIA receiver channels are available to all APEX observers.

  1. Prions: Beyond a Single Protein

    Science.gov (United States)

    Das, Alvin S.

    2016-01-01

    SUMMARY Since the term protein was first coined in 1838 and protein was discovered to be the essential component of fibrin and albumin, all cellular proteins were presumed to play beneficial roles in plants and mammals. However, in 1967, Griffith proposed that proteins could be infectious pathogens and postulated their involvement in scrapie, a universally fatal transmissible spongiform encephalopathy in goats and sheep. Nevertheless, this novel hypothesis had not been evidenced until 1982, when Prusiner and coworkers purified infectious particles from scrapie-infected hamster brains and demonstrated that they consisted of a specific protein that he called a “prion.” Unprecedentedly, the infectious prion pathogen is actually derived from its endogenous cellular form in the central nervous system. Unlike other infectious agents, such as bacteria, viruses, and fungi, prions do not contain genetic materials such as DNA or RNA. The unique traits and genetic information of prions are believed to be encoded within the conformational structure and posttranslational modifications of the proteins. Remarkably, prion-like behavior has been recently observed in other cellular proteins—not only in pathogenic roles but also serving physiological functions. The significance of these fascinating developments in prion biology is far beyond the scope of a single cellular protein and its related disease. PMID:27226089

  2. Nonlinear Single Spin Spectrum Analayzer

    Science.gov (United States)

    Kotler, Shlomi; Akerman, Nitzan; Glickman, Yinnon; Ozeri, Roee

    2014-05-01

    Qubits are excellent probes of their environment. When operating in the linear regime, they can be used as linear spectrum analyzers of the noise processes surrounding them. These methods fail for strong non-Gaussian noise where the qubit response is no longer linear. Here we solve the problem of nonlinear spectral analysis, required for strongly coupled environments. Our non-perturbative analytic model shows a nonlinear signal dependence on noise power, resulting in a spectral resolution beyond the Fourier limit as well as frequency mixing. We developed a noise characterization scheme adapted to this non-linearity. We then applied it using a single trapped 88Sr+ ion as the a sensitive probe of strong, non-Gaussian, discrete magnetic field noise. With this method, we attained a ten fold improvement over the standard Fourier limit. Finally, we experimentally compared the performance of equidistant vs. Uhrig modulation schemes for spectral analysis. Phys. Rev. Lett. 110, 110503 (2013), Synopsis at http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.110.110503 Current position: National Institute of Standards and Tehcnology, Boulder, CO.

  3. Crystal ball single event display

    International Nuclear Information System (INIS)

    Grosnick, D.; Gibson, A.; Allgower, C.; Alyea, J.; Argonne National Lab., IL

    1997-01-01

    The Single Event Display (SED) is a routine that is designed to provide information graphically about a triggered event within the Crystal Ball. The SED is written entirely in FORTRAN and uses the CERN-based HICZ graphing package. The primary display shows the amount of energy deposited in each of the NaI crystals on a Mercator-like projection of the crystals. Ten different shades and colors correspond to varying amounts of energy deposited within a crystal. Information about energy clusters is displayed on the crystal map by outlining in red the thirteen (or twelve) crystals contained within a cluster and assigning each cluster a number. Additional information about energy clusters is provided in a series of boxes containing useful data about the energy distribution among the crystals within the cluster. Other information shown on the event display include the event trigger type and data about π o 's and η's formed from pairs of clusters as found by the analyzer. A description of the major features is given, along with some information on how to install the SED into the analyzer

  4. Single-Organ Gallbladder Vasculitis

    Science.gov (United States)

    Hernández-Rodríguez, José; Tan, Carmela D.; Rodríguez, E. René; Hoffman, Gary S.

    2014-01-01

    Abstract Systemic vasculitis (SV) involving abdominal structures usually has a poor prognosis. Gallbladder vasculitis (GV) has been reported as part of SV (GB-SV) and focal single-organ vasculitis (GB-SOV). We analyzed clinical and histologic characteristics of patients with GV to identify features that differentiate GB-SOV from the systemic forms of GV. To identify affected patients with GV we used pathology databases from our institution and an English-language PubMed search. Clinical manifestations, laboratory and histologic features, treatment administered, and outcomes were recorded. Patients were divided in 2 groups, GB-SOV and GB-SV. As in previous studies of single-organ vasculitis, GB-SOV was only considered to be a sustainable diagnosis if disease beyond the gallbladder was not apparent after a follow-up period of at least 6 months. Sixty-one well-characterized patients with GV were included (6 from our institution). There was no significant sex bias (32 female patients, 29 male). Median age was 52 years (range, 18–94 yr). GB-SOV was found in 20 (33%) and GB-SV in 41 (67%) patients. No differences were observed in age, sex frequency, or duration of gallbladder symptoms between groups. Past episodes of recurrent right-upper quadrant or abdominal pain and lithiasic cholecystitis were more frequent in GB-SOV patients, whereas acalculous cholecystitis occurred more often in GB-SV. In GB-SV, gallbladder-related symptoms occurred more often concomitantly with or after the systemic features, but they sometimes appeared before SV was fully developed (13.5%). Constitutional and musculoskeletal symptoms were reported only in GB-SV patients. Compared to GB-SOV, GB-SV patients presented more often with fever (62.5% vs 20%; p = 0.003) and exhibited higher erythrocyte sedimentation rate levels (80 ± 28 vs 37 ± 25 mm/h, respectively; p = 0.006). All GB-SV patients required glucocorticoids and 50% of them also received cytotoxic agents. Mortality in

  5. Involvement of DNA polymerase beta in repair of ionizing radiation damage as measured by in vitro plasmid assays.

    NARCIS (Netherlands)

    Vens, C.; Hofland, I.; Begg, A.C.

    2007-01-01

    Characteristic of damage introduced in DNA by ionizing radiation is the induction of a wide range of lesions. Single-strand breaks (SSBs) and base damages outnumber double-strand breaks (DSBs). If unrepaired, these lesions can lead to DSBs and increased mutagenesis. XRCC1 and DNA polymerase beta

  6. Reduction of intracellular glutathione content and radiosensitivity

    International Nuclear Information System (INIS)

    Vos, O.; Schans, G.P. van der; Roos-Verheij, W.S.D.

    1986-05-01

    The intracellular glutathione (GSH) content in HeLa, CHO and V79 cells was reduced by incubating the cells in growth medium containing buthionine sulfoximine (BSO) or diethyl maleate (DEM). Clonogenicity, single strand DNA breaks (ssb) and double strand DNA breaks (dsb) were used as criteria for radiation induced damage after X- or γ irradiation. In survival experiments DEM gave a slightly larger sensitization although it gave a smaller reduction of the intracellular GSH. In general, sensitization was larger for dsb than for ssb, also the reduction of the OER was generally larger for dsb than for ssb. This may be due to the higher dose rate in case of dsb experiments resulting in a higher rate of radiochemical oxygen consumption. In general, no effect was found on post-irradiation repair of ssb and dsb. (Auth.)

  7. Dynamical supersymmetry breaking on magnetized tori and orbifolds

    Directory of Open Access Journals (Sweden)

    Hiroyuki Abe

    2016-10-01

    Full Text Available We construct several dynamical supersymmetry breaking (DSB models within a single ten-dimensional supersymmetric Yang–Mills (SYM theory, compactified on magnetized tori with or without orbifolding. We study the case that the supersymmetry breaking is triggered by a strong dynamics of SU(NC SYM theory with NF flavors contained in the four-dimensional effective theory. We show several configurations of magnetic fluxes and orbifolds, those potentially yield, below the compactification scale, the field contents and couplings required for triggering DSB. We especially find a class of self-complete DSB models on orbifolds, where all the extra fields are eliminated by the orbifold projection and DSB successfully occurs within the given framework. Comments on some perspectives for associating the obtained DSB models with the other sectors, such as the visible sector and another hidden sector for, e.g., stabilizing moduli, are also given.

  8. Reduction of intracellular glutathione content and radiosensitivity

    International Nuclear Information System (INIS)

    Vos, O.; Schans, G.P. van der; Roos-Verheij, W.S.D.

    1986-01-01

    The intracellular glutathione (GSH) content of HeLa, CHO and V79 cells was reduced by incubating the cells in growth medium containing buthionine sulphoximine or diethyl maleate (DEM). Clonogenicity, single-strand DNA breaks (ssb) and double-strand DNA breaks (dsb) were used as criteria for radiation-induced damage after X- or γ-irradiation. In survival experiments, DEM gave a slightly larger sensitization although it gave a smaller reduction of the intracellular GSH. In general, sensitization was larger for dsb than for ssb, also the reduction of the o.e.r. was generally larger for dsb than for ssb. This may be due to the higher dose rate in case of dsb experiments resulting in a higher rate of radiochemical oxygen consumption. In general, no effect was found on post-irradiation repair of ssb and dsb. (author)

  9. Tailoring single-photon and multiphoton probabilities of a single-photon on-demand source

    International Nuclear Information System (INIS)

    Migdall, A.L.; Branning, D.; Castelletto, S.

    2002-01-01

    As typically implemented, single-photon sources cannot be made to produce single photons with high probability, while simultaneously suppressing the probability of yielding two or more photons. Because of this, single-photon sources cannot really produce single photons on demand. We describe a multiplexed system that allows the probabilities of producing one and more photons to be adjusted independently, enabling a much better approximation of a source of single photons on demand

  10. The formation of double-strand breaks at multiply damaged sites is driven by the kinetics of excision/incision at base damage in eukaryotic cells

    International Nuclear Information System (INIS)

    Kozmin, S.G.; Sedletska, Y.; Reynaud-Angelin, A.; Sage, E.; Kozmin, S.G.; Sedletska, Y.; Reynaud-Angelin, A.; Sage, E.; Gasparutto, D.

    2009-01-01

    It has been stipulated that repair of clustered DNA lesions may be compromised, possibly leading to the formation of double-strand breaks (DSB) and, thus, to deleterious events. Using a variety of model multiply damaged sites (MDS), we investigated parameters that govern the formation of DSB during the processing of MDS. Duplexes carrying MDS were inserted into replicative or integrative vectors, and used to transform yeast Saccharomyces cerevisiae. Formation of DSB was assessed by a relevant plasmid survival assay. Kinetics of excision/incision and DSB formation at MDS was explored using yeast cell extracts. We show that MDS composed of two uracils or abasic sites, were rapidly incised and readily converted into DSB in yeast cells. In marked contrast, none of the MDS carrying opposed oG and hU separated by 38 bp gave rise to DSB, despite the fact that some of them contained preexisting single-strand break (a 1-nt gap). Interestingly, the absence of DSB formation in this case correlated with slow excision/incision rates of lesions. We propose that the kinetics of the initial repair steps at MDS is a major parameter that direct towards the conversion of MDS into DSB. Data provides clues to the biological consequences of MDS in eukaryotic cells. (authors)

  11. Laparoendoscopic single site (LESS) cholecystectomy.

    Science.gov (United States)

    Hodgett, Steven E; Hernandez, Jonathan M; Morton, Connor A; Ross, Sharona B; Albrink, Michael; Rosemurgy, Alexander S

    2009-02-01

    The journey from conventional "open" operations to truly "minimally invasive" operations naturally includes progression from operations involving multiple trocars and multiple incisions to operations involving access through the umbilicus alone. Laparoscopic operations through the umbilicus alone, laparoendoscopic single site surgery (LESS), offer improved cosmesis and hopes for less pain and improved recovery. This study was undertaken to evaluate our initial experience with LESS cholecystectomy and to compare our initial experience to concurrent outcomes with more conventional multiport, multi-incision laparoscopic cholecystectomy. All patients referred for cholecystectomy over a 6-month period were offered LESS. Outcomes, including blood loss, operative time, complications, and length of stay were recorded. Outcomes with our first LESS cholecystectomies were compared to an uncontrolled group of concurrent patients undergoing multiport, multi-incision laparoscopic cholecystectomy at the same hospital by the same surgeon. Twenty-nine patients of median age 50 years undergoing LESS cholecystectomy from November 2007 until May 2008 were compared to 29* patients, median age 48 years, undergoing standard multiport, multiple-incision laparoscopic cholecystectomy over the same time period. Median operative time for patients undergoing LESS cholecystectomy was 72 min and was not different from that of patients undergoing multiport, multi-incision laparoscopic cholecystectomy (p = 0.81). Median length of hospital stay was 1.0 day for patients undergoing LESS cholecystectomy and was not different from patients undergoing standard laparoscopic cholecystectomy (p = 0.46). Operative estimated blood loss was less than 100 cc for all patients. No patients undergoing attempted LESS cholecystectomy had conversions to "open" operations; two patients had an additional trocar(s) placed distant from the umbilicus to aid in exposure. Three patients undergoing LESS cholecystectomy had

  12. Single Cell Assay for Analyzing Single Cell Exosome and Endocrine Secretion and Cancer Markers

    Science.gov (United States)

    Chiu, Yu-Jui

    To understand the inhomogeneity of cells in biological systems, there is a growing demand for the capability to characterize the properties of individual single cells. Since single cell studies require continuous monitoring of the cell behaviors instead of a snapshot test at a single time point, an effective single-cell assay that can support time lapsed studies in a high throughput manner is desired. Most currently available single-cell technologies cannot provide proper environments to sustain cell growth and cannot provide, for appropriate cell types, proliferation of single cells and convenient, non-invasive tests of single cell behaviors from molecular markers. In this dissertation, I present a highly versatile single-cell assay that can accommodate different cellular types, enable easy and efficient single cell loading and culturing, and be suitable for the study of effects of in-vitro environmental factors in combination with drug screening. The salient features of the assay are the non-invasive collection and surveying of single cell secretions at different time points and massively parallel translocation of single cells by user defined criteria, producing very high compatibility to the downstream process such as single cell qPCR and sequencing. Above all, the acquired information is quantitative -- for example, one of the studies is measured by the number of exosomes each single cell secretes for a given time period. Therefore, our single-cell assay provides a convenient, low-cost, and enabling tool for quantitative, time lapsed studies of single cell properties.

  13. Single Molecule Applications of Quantum Dots

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Elmelund; Jauffred, Liselotte; Brewer, Jonathan R.

    2013-01-01

    Fluorescent nanocrystals composed of semiconductor materials were first introduced for biological applications in the late 1990s. The focus of this review is to give a brief survey of biological applications of quantum dots (QDs) at the single QD sensitivity level. These are described as follows: 1......) QD blinking and bleaching statistics, 2) the use of QDs in high speed single particle tracking with a special focus on how to design the biofunctional coatings of QDs which enable specific targeting to single proteins or lipids of interest, 3) a hybrid lipid-DNA analogue binding QDs which allows...... for tracking single lipids in lipid bilayers, 4) two-photon fluorescence correlation spectroscopy of QDs and 5) optical trapping and excitation of single QDs. In all of these applications, the focus is on the single particle sensitivity level of QDs. The high applicability of QDs in live cell imaging...

  14. Single molecule detection, thermal fluctuation and life

    Science.gov (United States)

    YANAGIDA, Toshio; ISHII, Yoshiharu

    2017-01-01

    Single molecule detection has contributed to our understanding of the unique mechanisms of life. Unlike artificial man-made machines, biological molecular machines integrate thermal noises rather than avoid them. For example, single molecule detection has demonstrated that myosin motors undergo biased Brownian motion for stepwise movement and that single protein molecules spontaneously change their conformation, for switching to interactions with other proteins, in response to thermal fluctuation. Thus, molecular machines have flexibility and efficiency not seen in artificial machines. PMID:28190869

  15. Single cell enzyme diagnosis on the chip

    DEFF Research Database (Denmark)

    Jensen, Sissel Juul; Harmsen, Charlotte; Nielsen, Mette Juul

    2013-01-01

    Conventional diagnosis based on ensemble measurements often overlooks the variation among cells. Here, we present a droplet-microfluidics based platform to investigate single cell activities. Adopting a previously developed isothermal rolling circle amplification-based assay, we demonstrate...... detection of enzymatic activities down to the single cell level with small quantities of biological samples, which outcompetes existing techniques. Such a system, capable of resolving single cell activities, will ultimately have clinical applications in diagnosis, prediction of drug response and treatment...

  16. Search for Single Top Production at LEP

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, M; Doria, A; Dova, M T; Duchesneau, D; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, P; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R P; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

    2002-01-01

    Single top production in e^+e^- annihilations is searched for in data collected by the L3 detector at centre-of-mass energies from 189 to 209 GeV, corresponding to a total integrated luminosity of 634 pb-1. Investigating hadronic and semileptonic top decays, no evidence of single top production at LEP is obtained and upper limits on the single top cross section as a function of the centre-of-mass energy are derived. Limits on possible anomalous couplings, as well as on the scale of contact interactions responsible for single top production are determined.

  17. Nano-manipulation of single DNA molecules

    International Nuclear Information System (INIS)

    Hu Jun; Shanghai Jiaotong Univ., Shanghai; Lv Junhong; Wang Guohua; Wang Ying; Li Minqian; Zhang Yi; Li Bin; Li Haikuo; An Hongjie

    2004-01-01

    Nano-manipulation of single atoms and molecules is a critical technique in nanoscience and nanotechnology. This review paper will focus on the recent development of the manipulation of single DNA molecules based on atomic force microscopy (AFM). Precise manipulation has been realized including varied manipulating modes such as 'cutting', 'pushing', 'folding', 'kneading', 'picking up', 'dipping', etc. The cutting accuracy is dominated by the size of the AFM tip, which is usually 10 nm or less. Single DNA fragments can be cut and picked up and then amplified by single molecule PCR. Thus positioning isolation and sequencing can be performed. (authors)

  18. Single top quark production with CMS

    Directory of Open Access Journals (Sweden)

    Piccolo Davide

    2013-11-01

    Full Text Available Measurements of single top quark production performed using the CMS experiment [1] data collected in 2011 at centre-of-mass energies of 7 TeV and in 2012 at 8 TeV, are presented. The cross sections for the electroweak production of single top quarks in the t-channel and in association with W-bosons is measured and the results are used to place constraints on the CKM matrix element Vtb. Measurements of top quark properties in single top quark production are also presented. The results include the measurement of the charge ratio in the single top t-channel.

  19. Sexual behavior of single adult American women.

    Science.gov (United States)

    Duberstein Lindberg, Laura; Singh, Susheela

    2008-03-01

    Public policies promoting abstinence until marriage attempt to influence the sexual behavior of the more than 18 million American women who are currently single. An analysis of these women's behavior is needed to inform policies that are responsive to their sexual and reproductive health needs. Sexual behaviors, risk factors and reproductive health needs were examined among a nationally representative sample of 6,493 women aged 20-44 from the 2002 National Survey of Family Growth. Paired t tests were used to assess differences among single, married and cohabiting women by selected demographic, behavioral and risk measures. Thirty-six percent of women aged 20-44 are single, and nine in 10 single women are sexually experienced. Seventy percent of the latter women are currently sexually active; on average, they had intercourse in seven of the last 12 months. A higher proportion of single women (22%) than of cohabiting (9%) or married women (2%) have had two or more partners in the past year, and half of single women are at risk of unintended pregnancy. Furthermore, single women and cohabiting women are more likely to lack health insurance than are married women (21-25% vs. 12%). Because of the high level of sexual activity among single adult women, providers must address their reproductive health care needs and offer appropriate counseling and services. Government policies aimed at encouraging adult women to have sex only within marriage appear out of touch with the reality of the sexual behavior of single women.

  20. Single port VATS: recent developments in Asia.

    Science.gov (United States)

    Yu, Peter S Y; Capili, Freddie; Ng, Calvin S H

    2016-03-01

    Single port video-assisted thoracic surgery (VATS) is the most recent evolution in minimally invasive thoracic surgery. With increasing global popularity, the single port VATS approach has been adopted by experienced thoracic surgeons in many Asian countries. From initial experience of single port VATS lobectomy to the more complex sleeve resection procedures now forming part of daily practice in some Asia institutes, the region has been the proving ground for single port VATS approaches' feasibility and safety. In addition, certain technical refinements in single port VATS lung resection and lymph node dissection have also sprung from Asia. Novel equipment designed to facilitate single port VATS allowing further reduce access trauma are being realized by the partnership between surgeons and the industries. Advanced thoracoscopes and staplers that are narrower and more maneuverable are particularly important in the smaller habitus of patients from Asia. These and similar new generation equipment are being applied to single port VATS in novel ways. As dedicated thoracic surgeons in the region continue to striving for excellence, innovative ideas in single incision access including subxiphoid and embryonic natural-orifice transluminal endoscopic surgery (e-NOTES) have been explored. Adjunct techniques and technology used in association with single port VATS such as non-intubated surgery, hybrid operating room image guidance and electromagnetic navigational bronchoscopy are all in rapid development in Asia.

  1. Self-Concept of Single Women.

    Science.gov (United States)

    Gigy, Lynn L.

    1980-01-01

    Explores the self-concepts of single and married women. Single women had more psychiatric symptoms, valued personal growth and achievement, and were higher on assertion and poise. Married women were more likely to identify with kinship roles and household activities. (Author)

  2. Electrically Anisotropic Layered Perovskite Single Crystal

    KAUST Repository

    Li, Ting-You

    2016-01-01

    -23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating

  3. Confinement stabilises single crystal vaterite rods.

    OpenAIRE

    Schenk, AS; Albarracin, EJ; Kim, YY; Ihli, J; Meldrum, FC

    2014-01-01

    Single-crystals of vaterite, the least-stable anhydrous polymorph of CaCO3, are rare in biogenic and synthetic systems. We here describe the synthesis of high aspect ratio single crystal vaterite rods under additive-free conditions by precipitating CaCO3 within the cylindrical pores of track-etch membranes.

  4. Single-Level and Multilevel Mediation Analysis

    Science.gov (United States)

    Tofighi, Davood; Thoemmes, Felix

    2014-01-01

    Mediation analysis is a statistical approach used to examine how the effect of an independent variable on an outcome is transmitted through an intervening variable (mediator). In this article, we provide a gentle introduction to single-level and multilevel mediation analyses. Using single-level data, we demonstrate an application of structural…

  5. Reducing deaths in single vehicle collisions.

    NARCIS (Netherlands)

    Adminaite, D. Jost, G. Stipdonk, H. & Ward, H.

    2017-01-01

    A third of road deaths in the EU are caused by collisions that involve a single motorised vehicle where the driver, rider and/or passengers are killed but no other road users are involved. These single vehicle collisions (SVCs), and how to prevent them occurring, are the subject of this report.

  6. Single Mother Parenting and Adolescent Psychopathology.

    Science.gov (United States)

    Daryanani, Issar; Hamilton, Jessica L; Abramson, Lyn Y; Alloy, Lauren B

    2016-10-01

    Children raised in single-mother families are at increased risk for psychopathology, but the mechanisms that help explain this relationship are understudied. In a community sample of diverse adolescents (N = 385, 52 % female, 48 % Caucasian) and their mothers, we hypothesized that single mothers would be more likely than cohabitating mothers to engage in negative parenting behaviors, which would predict adolescent psychopathology prospectively. Single mothers were more likely to engage in psychologically controlling behaviors, which predicted to their adolescent offspring experiencing higher rates of depressive symptoms and externalizing disorders. Girls were more susceptible to depressive symptoms via psychologically controlling parenting than boys in single-mother families. Further, single mothers were more likely to engage in rejecting parenting behaviors, which predicted to a higher prevalence of adolescent externalizing disorders. Surprisingly, rejection in single-mother families predicted to less severe anxiety symptoms in adolescents relative to two-parent families. It is likely that single mothers are not inherently inferior parents relative to cohabitating mothers; rather, their parenting practices are often compromised by a myriad of demands and stressors. Consistent with this postulate, low socioeconomic status was associated with single motherhood and negative parenting behaviors. Clinical implications and study limitations are discussed.

  7. BILATERAL SINGLE SESSION URETEROSCOPY FOR URETERAL ...

    African Journals Online (AJOL)

    Objectives: To determine the feasibility, safety and success rate of bilateral single session rigid retrograde ureteroscopy (URS) for bilateral ureteral calculi. Patients and Methods: Thirty-five patients underwent bilateral single session ureteroscopic calculus removal. Results: Out of 70 renal units in 35 patients treated, ...

  8. Experience with single-layer rectal anastomosis.

    OpenAIRE

    Khubchandani, M; Upson, J

    1981-01-01

    Anastomotic dehiscence following resection of the large intestine is a serious complication. Satisfactory results of single-layer anastomosis depend upon meticulous technique and a scrupulously clean colon. Out of 65 single-layer anastomoses involving the rectum, significant leakage occurred in 4 patients. The results are reported in order to draw attention to the safety and efficacy of one-layer anastomosis.

  9. Saha equation, single and two particle states

    International Nuclear Information System (INIS)

    Kraeft, W.D.; Girardeau, M.D.; Strege, B.

    1990-01-01

    Single and two particle porperties in dense plasma are discussed in connection with their role in the mass action law for a partially ionized plasma. The two particle bound states are nearly density independent, while the continuum is essentially shifted. The single particle states are damped, and their energy has a negative shift and a parabolic behaviour for small momenta. (orig.)

  10. Single-Gender Education: Educators' Perspective

    Science.gov (United States)

    Fry, John P.

    2009-01-01

    The examination of educator's views regarding single-gender education was the basis of this study. The significance of the intended study is to show the educator's view of single-gender education as it relates to student academic achievement and behavioral incidents. A quantitative study was conducted utilizing a sample population of regular and…

  11. Single port access for laparoscopic lateral segmentectomy.

    Science.gov (United States)

    Inoue, Yoshihiro; Asakuma, Mitsuhiro; Hirokawa, Fumitoshi; Hayashi, Michihiro; Shimizu, Tetsunosuke; Uchiyama, Kazuhisa

    2017-12-01

    Single-port access laparoscopic lateral segmentectomy (LLS) has been developed as a novel minimally invasive surgery. We have experience with this LLS technique. To report our technique and patients' postoperative course in a series of single-port access LLS performed in our department. We also examine the cosmetic outcome, safety, and utility of the procedure. Between February 2010 and October 2016, 54 patients who underwent single- or multiple-port laparoscopic or open lateral segmentectomy (LS) were retrospectively analyzed with respect to cosmetic outcome, safety, and utility. In the single LLS group, the laparoscopic procedure was successfully completed for all 14 patients. The median operative time was significantly shorter in the single LLS group (123 min; range: 50-270 min) than in the other groups. Estimated blood loss was also significantly lower in the single LLS group (10 ml; range: 0-330 ml). During the first 7 postoperative days, the visual analog scale pain score and the use of additional analgesia were not significantly different between groups. The single LLS group had a 7.1% complication rate (Clavien-Dindo classification > IIIA); this was not significantly different between groups. Single-port access LLS is a procedure with excellent cosmetic results, although, with regard to invasiveness, there are no major differences from conventional LLS.

  12. A practical alternative to single tree selection?

    Science.gov (United States)

    Gary W. Miller; H. Clay Smith

    1993-01-01

    When landowners want to develop and maintain an uneven-aged tree structure in eastern hardwood stands, single-tree selection often is suggested as the only advisable, long-term partial regeneration harvest method. Single-tree selection is preferred because it provides a means for improving quality and controlling stocking of the residual stand necessary for sustained...

  13. Single Finds. The case of Roman Egypt

    DEFF Research Database (Denmark)

    Christiansen, Erik

    2006-01-01

    Survery of single or stray finds from Roman Egypt and discussion of them as evidence for the circulation and use of coins......Survery of single or stray finds from Roman Egypt and discussion of them as evidence for the circulation and use of coins...

  14. Coupling single emitters to quantum plasmonic circuits

    DEFF Research Database (Denmark)

    Huck, Alexander; Andersen, Ulrik Lund

    2016-01-01

    In recent years, the controlled coupling of single-photon emitters to propagating surface plasmons has been intensely studied, which is fueled by the prospect of a giant photonic nonlinearity on a nanoscaled platform. In this article, we will review the recent progress on coupling single emitters...

  15. Extracting Models in Single Molecule Experiments

    Science.gov (United States)

    Presse, Steve

    2013-03-01

    Single molecule experiments can now monitor the journey of a protein from its assembly near a ribosome to its proteolytic demise. Ideally all single molecule data should be self-explanatory. However data originating from single molecule experiments is particularly challenging to interpret on account of fluctuations and noise at such small scales. Realistically, basic understanding comes from models carefully extracted from the noisy data. Statistical mechanics, and maximum entropy in particular, provide a powerful framework for accomplishing this task in a principled fashion. Here I will discuss our work in extracting conformational memory from single molecule force spectroscopy experiments on large biomolecules. One clear advantage of this method is that we let the data tend towards the correct model, we do not fit the data. I will show that the dynamical model of the single molecule dynamics which emerges from this analysis is often more textured and complex than could otherwise come from fitting the data to a pre-conceived model.

  16. Single-incision total laparoscopic hysterectomy

    Directory of Open Access Journals (Sweden)

    Sinha Rakesh

    2011-01-01

    Full Text Available Single-incision laparoscopic surgery is an alternative to conventional multiport laparoscopy. Single-access laparoscopy using a transumbilical port affords maximum cosmetic benefits because the surgical incision is hidden in the umbilicus. The advantages of single-access laparoscopic surgery may include less bleeding, infection, and hernia formation and better cosmetic outcome and less pain. The disadvantages and limitations include longer surgery time, difficulty in learning the technique, and the need for specialized instruments. Ongoing refinement of the surgical technique and instrumentation is likely to expand its role in gynecologic surgery in the future. We perform single-incision total laparoscopic hysterectomy using three ports in the single transumbilical incision.

  17. Single-event effect ground test issues

    International Nuclear Information System (INIS)

    Koga, R.

    1996-01-01

    Ground-based single event effect (SEE) testing of microcircuits permits characterization of device susceptibility to various radiation induced disturbances, including: (1) single event upset (SEU) and single event latchup (SEL) in digital microcircuits; (2) single event gate rupture (SEGR), and single event burnout (SEB) in power transistors; and (3) bit errors in photonic devices. These characterizations can then be used to generate predictions of device performance in the space radiation environment. This paper provides a general overview of ground-based SEE testing and examines in critical depth several underlying conceptual constructs relevant to the conduct of such tests and to the proper interpretation of results. These more traditional issues are contrasted with emerging concerns related to the testing of modern, advanced microcircuits

  18. Radiation-biological investigations with multicellular spheroids as an in vitro tumour model. 2

    International Nuclear Information System (INIS)

    Koerner, I.J.; Kopp, J.; Malz, W.

    1978-01-01

    Using the alkaline sucrose gradient sedimentation technique, the single-strand break rejoining in single cells and cells of small sheroids was studied after X-irradiation with 10 krads. The half life time for the fast rejoining process amounts to about 4 minutes for single cells and to about 1.5 minutes for small spheroids. While in single cells 7 per cent of single-strand breaks remain unrepaired after 80 minutes incubation at 37 0 C, in small spheroids practically no residual unrepaired single-strand breaks can be detected after more than 20 minutes. The corresponding survival of cells of small sheroids is increased in comparison with single cells. Possible reasons are discussed for the different repair capacities found. (author)

  19. Coherent single-photon absorption by single emitters coupled to 1D nanophotonic waveguides

    DEFF Research Database (Denmark)

    Chen, Yuntian; Wubs, Martijn; Mørk, Jesper

    2012-01-01

    We have derived an efficient model that allows calculating the dynamical single-photon absorption of an emitter coupled to a waveguide. We suggest a novel and simple structure that leads to strong single-photon absorption.......We have derived an efficient model that allows calculating the dynamical single-photon absorption of an emitter coupled to a waveguide. We suggest a novel and simple structure that leads to strong single-photon absorption....

  20. A Single Father's Shopping Bag: Purchasing Decisions in Single-Father Families

    Science.gov (United States)

    Ziol-Guest, Kathleen M.

    2009-01-01

    Using data from the 1980 to 2003 panels of the Consumer Expenditure Survey, this article examines purchasing decisions in father-headed single-parent families. Single-father expenditures are compared to both married-parent expenditures and single-mother expenditures on 17 broad categories of household-level goods and services. Multivariate…

  1. Single-molecule dynamics in nanofabricated traps

    Science.gov (United States)

    Cohen, Adam

    2009-03-01

    The Anti-Brownian Electrokinetic trap (ABEL trap) provides a means to immobilize a single fluorescent molecule in solution, without surface attachment chemistry. The ABEL trap works by tracking the Brownian motion of a single molecule, and applying feedback electric fields to induce an electrokinetic motion that approximately cancels the Brownian motion. We present a new design for the ABEL trap that allows smaller molecules to be trapped and more information to be extracted from the dynamics of a single molecule than was previously possible. In particular, we present strategies for extracting dynamically fluctuating mobilities and diffusion coefficients, as a means to probe dynamic changes in molecular charge and shape. If one trapped molecule is good, many trapped molecules are better. An array of single molecules in solution, each immobilized without surface attachment chemistry, provides an ideal test-bed for single-molecule analyses of intramolecular dynamics and intermolecular interactions. We present a technology for creating such an array, using a fused silica plate with nanofabricated dimples and a removable cover for sealing single molecules within the dimples. With this device one can watch the shape fluctuations of single molecules of DNA or study cooperative interactions in weakly associating protein complexes.

  2. Relaxor-PT Single Crystal Piezoelectric Sensors

    Directory of Open Access Journals (Sweden)

    Xiaoning Jiang

    2014-07-01

    Full Text Available Relaxor-PbTiO3 piezoelectric single crystals have been widely used in a broad range of electromechanical devices, including piezoelectric sensors, actuators, and transducers. This paper reviews the unique properties of these single crystals for piezoelectric sensors. Design, fabrication and characterization of various relaxor-PT single crystal piezoelectric sensors and their applications are presented and compared with their piezoelectric ceramic counterparts. Newly applicable fields and future trends of relaxor-PT sensors are also suggested in this review paper.

  3. Single-cell technologies in environmental omics

    KAUST Repository

    Kodzius, Rimantas; Gojobori, Takashi

    2015-01-01

    Environmental studies are primarily done by culturing isolated microorganisms or by amplifying and sequencing conserved genes. Difficulties understanding the complexity of large numbers of various microorganisms in an environment led to the development of techniques to enrich specific microorganisms for upstream analysis, ultimately leading to single-cell isolation and analyses. We discuss the significance of single-cell technologies in omics studies with focus on metagenomics and metatranscriptomics. We propose that by reducing sample heterogeneity using single-cell genomics, metaomic studies can be simplified.

  4. Single-cell technologies in environmental omics

    KAUST Repository

    Kodzius, Rimantas

    2015-10-22

    Environmental studies are primarily done by culturing isolated microorganisms or by amplifying and sequencing conserved genes. Difficulties understanding the complexity of large numbers of various microorganisms in an environment led to the development of techniques to enrich specific microorganisms for upstream analysis, ultimately leading to single-cell isolation and analyses. We discuss the significance of single-cell technologies in omics studies with focus on metagenomics and metatranscriptomics. We propose that by reducing sample heterogeneity using single-cell genomics, metaomic studies can be simplified.

  5. CP Violation in Single Top Quark Production

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Weigang [Michigan State Univ., East Lansing, MI (United States)

    2012-01-01

    We present a search for CP violation in single top quark production with the DØ experiment at the Tevatron proton-antiproton collider. CP violation in the top electroweak interaction results in different single top quark production cross sections for top and antitop quarks. We perform the search in the single top quark final state using 5.4 fb-1 of data, in the s-channel, t-channel, and for both combined. At this time, we do not see an observable CP asymmetry.

  6. Single-instruction multiple-data execution

    CERN Document Server

    Hughes, Christopher J

    2015-01-01

    Having hit power limitations to even more aggressive out-of-order execution in processor cores, many architects in the past decade have turned to single-instruction-multiple-data (SIMD) execution to increase single-threaded performance. SIMD execution, or having a single instruction drive execution of an identical operation on multiple data items, was already well established as a technique to efficiently exploit data parallelism. Furthermore, support for it was already included in many commodity processors. However, in the past decade, SIMD execution has seen a dramatic increase in the set of

  7. Thermally activated, single component epoxy systems

    KAUST Repository

    Unruh, David A.

    2011-08-23

    A single component epoxy system in which the resin and hardener components found in many two-component epoxies are combined onto the same molecule is described. The single molecule precursor to the epoxy resin contains both multiple epoxide moieties and a diamine held latent by thermally degradable carbamate linkages. These bis-carbamate "single molecule epoxies" have an essentially infinite shelf life and access a significant range in curing temperatures related to the structure of the carbamate linkages used. © 2011 American Chemical Society.

  8. Thermally activated, single component epoxy systems

    KAUST Repository

    Unruh, David A.; Pastine, Stefan J.; Moreton, Jessica C.; Frechet, Jean

    2011-01-01

    A single component epoxy system in which the resin and hardener components found in many two-component epoxies are combined onto the same molecule is described. The single molecule precursor to the epoxy resin contains both multiple epoxide moieties and a diamine held latent by thermally degradable carbamate linkages. These bis-carbamate "single molecule epoxies" have an essentially infinite shelf life and access a significant range in curing temperatures related to the structure of the carbamate linkages used. © 2011 American Chemical Society.

  9. Single spin asymmetry for charm mesons

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez Zacarias, G. [PIMAyC, Eje Central Lazaro Cardenas No. 152, Apdo. Postal 14-805, D.F. (Mexico); Herrera, G.; Mercado, J. [Centro de Investigacion y de Estudios Avanzados, Apdo. Postal 14-740, D.F. (Mexico)

    2007-08-15

    We study single spin asymmetries of D{sup 0} and D{sup -} mesons in polarized proton-proton collisions. A two component model is used to describe charm meson production. The production of D mesons occurs by recombination of the constituents present in the initial state as well as by fragmentation of quarks in the final state. This model has proved to describe the production of charm. The recombination component involves a mechanism of spin alignment that ends up in a single spin asymmetry. Experimental measurements of single spin asymmetry for pions at RHIC are compared with the model. Predictions for the asymmetry in D mesons are presented. (orig.)

  10. Single spin asymmetry for charm mesons

    International Nuclear Information System (INIS)

    Dominguez Zacarias, G.; Herrera, G.; Mercado, J.

    2007-01-01

    We study single spin asymmetries of D 0 and D - mesons in polarized proton-proton collisions. A two component model is used to describe charm meson production. The production of D mesons occurs by recombination of the constituents present in the initial state as well as by fragmentation of quarks in the final state. This model has proved to describe the production of charm. The recombination component involves a mechanism of spin alignment that ends up in a single spin asymmetry. Experimental measurements of single spin asymmetry for pions at RHIC are compared with the model. Predictions for the asymmetry in D mesons are presented. (orig.)

  11. Automated Single Cell Data Decontamination Pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Tennessen, Kristin [Lawrence Berkeley National Lab. (LBNL), Walnut Creek, CA (United States). Dept. of Energy Joint Genome Inst.; Pati, Amrita [Lawrence Berkeley National Lab. (LBNL), Walnut Creek, CA (United States). Dept. of Energy Joint Genome Inst.

    2014-03-21

    Recent technological advancements in single-cell genomics have encouraged the classification and functional assessment of microorganisms from a wide span of the biospheres phylogeny.1,2 Environmental processes of interest to the DOE, such as bioremediation and carbon cycling, can be elucidated through the genomic lens of these unculturable microbes. However, contamination can occur at various stages of the single-cell sequencing process. Contaminated data can lead to wasted time and effort on meaningless analyses, inaccurate or erroneous conclusions, and pollution of public databases. A fully automated decontamination tool is necessary to prevent these instances and increase the throughput of the single-cell sequencing process

  12. Approaches to single-nanoparticle catalysis.

    Science.gov (United States)

    Sambur, Justin B; Chen, Peng

    2014-01-01

    Nanoparticles are among the most important industrial catalysts, with applications ranging from chemical manufacturing to energy conversion and storage. Heterogeneity is a general feature among these nanoparticles, with their individual differences in size, shape, and surface sites leading to variable, particle-specific catalytic activity. Assessing the activity of individual nanoparticles, preferably with subparticle resolution, is thus desired and vital to the development of efficient catalysts. It is challenging to measure the activity of single-nanoparticle catalysts, however. Several experimental approaches have been developed to monitor catalysis on single nanoparticles, including electrochemical methods, single-molecule fluorescence microscopy, surface plasmon resonance spectroscopy, X-ray microscopy, and surface-enhanced Raman spectroscopy. This review focuses on these experimental approaches, the associated methods and strategies, and selected applications in studying single-nanoparticle catalysis with chemical selectivity, sensitivity, or subparticle spatial resolution.

  13. Single DNA denaturation and bubble dynamics

    International Nuclear Information System (INIS)

    Metzler, Ralf; Ambjoernsson, Tobias; Hanke, Andreas; Fogedby, Hans C

    2009-01-01

    While the Watson-Crick double-strand is the thermodynamically stable state of DNA in a wide range of temperature and salt conditions, even at physiological conditions local denaturation bubbles may open up spontaneously due to thermal activation. By raising the ambient temperature, titration, or by external forces in single molecule setups bubbles proliferate until full denaturation of the DNA occurs. Based on the Poland-Scheraga model we investigate both the equilibrium transition of DNA denaturation and the dynamics of the denaturation bubbles with respect to recent single DNA chain experiments for situations below, at, and above the denaturation transition. We also propose a new single molecule setup based on DNA constructs with two bubble zones to measure the bubble coalescence and extract the physical parameters relevant to DNA breathing. Finally we consider the interplay between denaturation bubbles and selectively single-stranded DNA binding proteins.

  14. Single Shell Tank (SST) Program Plan

    International Nuclear Information System (INIS)

    HAASS, C.C.

    2000-01-01

    This document provides an initial program plan for retrieval of the single-shell tank waste. Requirements, technical approach, schedule, organization, management, and cost and funding are discussed. The program plan will be refined and updated in fiscal year 2000

  15. Single Incision Laparoscopic Splenectomy: Our First Experiences

    Directory of Open Access Journals (Sweden)

    Umut Barbaros

    2011-06-01

    Full Text Available Objective: Most laparoscopic surgeons have attempted to reduce incisional morbidity and improve cosmetic outcomes by using less and smaller trocars. Single incision laparoscopic splenectomy is a new laparoscopic procedure. Herein we would like to present our experiences.Material and Methods: Between January 2009 and June 2009, data of the 7 patients who underwent single incision laparoscopic splenectomy were evaluated retrospectively.Results: There were 7 patients (5 females and 2 males with a mean age of 29.9 years. The most common splenectomy indication was idiopathic thrombocytopenic purpura. Single incision laparoscopic splenectomy was performed successfully in 6 patients. In one patient the operation was converted to an open procedure.Conclusion: With surgeons experienced in minimally invasive surgery, single incision laparoscopic splenectomy could be performed successfully. However, in order to demonstrate the differneces between standard laparoscopic splenectomy and SILS splenetomy, prospective randomized comparative studies are required.

  16. Single isospin decay amplitude and CP violation

    Energy Technology Data Exchange (ETDEWEB)

    Deshpande, N.G. [Oregon Univ., Eugene, OR (United States). Inst. of Theoretical Science; He, Xiaogang [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Pakvasa, S. [Hawaii Univ., Honolulu, HI (United States). Dept. of Physics and Astronomy

    1996-06-01

    While for K meson or hyperon decays, the partial rate asymmetries are always zero if the final states are single isospin states, in B decays the situation is dramatically different and partial rate asymmetries can be non-zero if the final states are single isospin states. Partial rate asymmetries were calculated for several B decays with single isospin amplitude in the finale states using factorization approximation. It was found that more intermediate on-shell states with different Cabbibbo-Kobayashi-Maskawa factors are allowed in B decay and CP violating partial rate asymmetries need not to be zero even if the final state contains only a single isospin state. 17 refs., 4 figs.

  17. A Variable Single Photon Plasmonic Beamsplitter

    DEFF Research Database (Denmark)

    Israelsen, Niels Møller; Kumar, Shailesh; Huck, Alexander

    Plasmonic structures can both be exploited for scaling down optical components beyond the diffraction limit and enhancing andcollecting the emission from a single dipole emitter. Here, we experimentally demonstrate adiabatic coupling between two silvernanowires using a nitrogen vacancy center as ...

  18. Defect free single crystal thin layer

    KAUST Repository

    Elafandy, Rami Tarek Mahmoud

    2016-01-28

    A gallium nitride film can be a dislocation free single crystal, which can be prepared by irradiating a surface of a substrate and contacting the surface with an etching solution that can selectively etch at dislocations.

  19. Who will resettle single Syrian men?

    Directory of Open Access Journals (Sweden)

    Lewis Turner

    2017-02-01

    Full Text Available Resettlement programmes for Syrian refugees severely restrict access to resettlement for single Syrian men, despite the conditions of vulnerability, insecurity and danger in which they live.

  20. Nanospintronics: when spintronics meets single electron physics

    International Nuclear Information System (INIS)

    Seneor, Pierre; Bernand-Mantel, Anne; Petroff, Frederic

    2007-01-01

    As spintronics goes nano, new phenomena are predicted resulting from the interplay between spin dependent transport and single electron physics. The long term goal of manipulating spins one by one would open a promising path to quantum computing. Towards this end, there is an ever-growing effort to connect spin tanks (i.e. ferromagnetic leads) to smaller and smaller objects in order to study spintronics in reduced dimensions. As the dimensions are reduced, spin dependent transport is predicted to interplay with quantum and/or single electron charging effects. We review experiments and theories on the interplay between Coulomb blockade and spin properties (namely magneto-Coulomb effects) in structures where a single nano-object is connected to ferromagnetic leads. We then discuss briefly future directions in the emerging field of nanospintronics towards quantum dots, carbon nanotubes and single molecule magnets

  1. Electric field imaging of single atoms

    Science.gov (United States)

    Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

    2017-01-01

    In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures. PMID:28555629

  2. Single bunched beam generation without subharmonic prebuncher

    International Nuclear Information System (INIS)

    Kobayashi, T.; Tagawa, S.

    1995-01-01

    The intensity of the accelerated single bunched electron beam depends on the performance of the electron gun and the fast cathode pulser. The electron beam is emitted by a Y-796 cathode assembly with a cathode of 2 cm 2 (8 A/cm 2 ), and an extracted voltage of 90 kV. The maximum charge of the single bunched beam was attained at 1.5 nC/pulse using SHB. Recently, a single bunched beam has been generated by an ultrafast cathode pulser (rise and fall time <100 ps pulse height -2 kV at 50 Ω) without SHB. The charge of the accelerated electron beam is about 40 pC/pulse (pulse width <10 ps) without the production of a satellite beam. This result show that a single bunched beam can be produced by the linear accelerator without SHB. ((orig.))

  3. Distributed Processing Using Single-chip Microcomputers

    National Research Council Canada - National Science Library

    Pritchett, William

    1996-01-01

    This project investigates the use of single-chip microprocessors as nodes in a token ring control network and explores the implementation of a protocol to manage communication across such a network...

  4. Single Family Loan Sale Initiative - National Offering

    Data.gov (United States)

    Department of Housing and Urban Development — The FHA Office of Housing is conducting a series of mortgage loan sales under the Single Family Loan Sale (SFLS) Initiative. The current sales structure consists of...

  5. Single Shell Tank (SST) Program Plan

    Energy Technology Data Exchange (ETDEWEB)

    HAASS, C.C.

    2000-03-21

    This document provides an initial program plan for retrieval of the single-shell tank waste. Requirements, technical approach, schedule, organization, management, and cost and funding are discussed. The program plan will be refined and updated in fiscal year 2000.

  6. Epigenetics reloaded: the single-cell revolution.

    Science.gov (United States)

    Bheda, Poonam; Schneider, Robert

    2014-11-01

    Mechanistically, how epigenetic states are inherited through cellular divisions remains an important open question in the chromatin field and beyond. Defining the heritability of epigenetic states and the underlying chromatin-based mechanisms within a population of cells is complicated due to cell heterogeneity combined with varying levels of stability of these states; thus, efforts must be focused toward single-cell analyses. The approaches presented here constitute the forefront of epigenetics research at the single-cell level using classic and innovative methods to dissect epigenetics mechanisms from the limited material available in a single cell. This review further outlines exciting future avenues of research to address the significance of epigenetic heterogeneity and the contributions of microfluidics technologies to single-cell isolation and analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Demonstration of Coupled Tiamat Single Assembly Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Novascone, Stephen R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hales, Jason D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gardner, Russell [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pawlowski, R. P. P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pastore, Giovanni [Idaho National Lab. (INL), Idaho Falls, ID (United States); Toth, Alex [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clarno, Kevin T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Collins, Benjamin S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stimpson, Shane G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Powers, Jeffrey J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-06-01

    This report corresponds to milestone L3:PHI.PCI.P15.03, which was originally intended to investigate the time discretization approaches with the newly developed fully coupled Tiamat capability, targeting single assembly problems.

  8. Single-photon manipulation in Nanophotonic Circuits

    DEFF Research Database (Denmark)

    Hansen, Sofie Lindskov

    Quantum dots in photonic nanostructures has long been known to be a very powerful and versatile solid-state platform for conducting quantum optics experiments. The present PhD thesis describes experimental demonstrations of single-photon generation and subsequent manipulation all realized...... on a gallium arsenide platform. This platform offers near-unity coupling between embedded single-photon emitters and a photonic mode, as well as the ability to suppress decoherence mechanisms, making it highly suited for quantum information applications. In this thesis we show how a single-photon router can...... be realized on a chip with embedded quantum dots. This allows for on-chip generation and manipulation of single photons. The router consists of an on-chip interferometer where the phase difference between the arms of the interferometer is controlled electrically. The response time of the device...

  9. Defect free single crystal thin layer

    KAUST Repository

    Elafandy, Rami Tarek Mahmoud; Ooi, Boon S.

    2016-01-01

    A gallium nitride film can be a dislocation free single crystal, which can be prepared by irradiating a surface of a substrate and contacting the surface with an etching solution that can selectively etch at dislocations.

  10. Barium Isotopes in Single Presolar Grains

    Science.gov (United States)

    Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.

    2001-01-01

    Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.

  11. A theoretical overview on single hard diffraction

    International Nuclear Information System (INIS)

    Wuesthoff, M.

    1996-01-01

    The concept of the Pomeron structure function and its application in Single Hard Diffraction at hadron colliders and in diffractive Deep Inelastic Scattering is critically reviewed. Some alternative approaches are briefly surveyed with a focus on QCD inspired models

  12. Single Top-Quark Production at CDF

    CERN Multimedia

    CERN. Geneva

    2008-01-01

    The main challenge of the single top-quark search at the Tevatron is the huge background from W+jets events and QCD events, which makes the use of advanced multivariate techniques essential. The recent single top analyses using either the matrix element method, neural networks, likelihood discriminants or boosted decision trees as well as the combination of the former three analyses will be presented...

  13. Bisimulation for Single-Agent Plausibility Models

    DEFF Research Database (Denmark)

    Andersen, Mikkel Birkegaard; Bolander, Thomas; van Ditmarsch, H.

    2013-01-01

    define a proper notion of bisimulation, and prove that bisimulation corresponds to logical equivalence on image-finite models. We relate our results to other epistemic notions, such as safe belief and degrees of belief. Our results imply that there are only finitely many non-bisimilar single......-agent epistemic plausibility models on a finite set of propositions. This gives decidability for single-agent epistemic plausibility planning....

  14. European Banking with a Single Currency

    OpenAIRE

    Jean Dermine

    1996-01-01

    At the Madrid summit in December 1995, the EU heads of state or government endorsed a three-phase plan for the introduction of the single currency. The purpose of the paper is to identify how, besides an obvious fall in revenue from intra-European currencies trading, a single currency will alter fundamentally and permanently European banking markets. A common currency will likely change the sources of competitive advantage in various markets such as those of government bonds and their fast gr...

  15. Single particle dynamics in circular accelerators

    International Nuclear Information System (INIS)

    Ruth, R.D.

    1986-10-01

    The purpose of this paper is to introduce the reader to the theory associated with the transverse dynamics of single particle, in circular accelerators. The discussion begins with a review of Hamiltonian dynamics and canonical transformations. The case of a single particle in a circular accelerator is considered with a discussion of non-linear terms and chromaticity. The canonical perturbation theory is presented and nonlinear resonances are considered. Finally, the concept of renormalization and residue criterion are examined. (FI)

  16. From Single Microparticles to Microfluidic Emulsification

    DEFF Research Database (Denmark)

    Kinoshita, K.; Ortiz, Elisa Parra; Hussein, Abdirazak

    2016-01-01

    The micropipette manipulation technique is capable of making fundamental single particle measurements and analyses. This information is critical for establishing processing parameters in systems such as microfluidics and homogenization. To demonstrate what can be achieved at the single particle l...... a very useful tool for understanding microsphere-processes and hence can help to establish process conditions without resorting to expensive and material-consuming bulk particle runs....

  17. Preparation of TiC single crystals

    International Nuclear Information System (INIS)

    Scheerer, B.; Fink, J.; Reichardt, W.

    1975-07-01

    TiC single crystals were prepared by vertical zone melting for measurements of the phonon dispersion by inelastic neutron scattering. The influence of the starting material and of the growing conditions on the growth of the crystal were studied. The crystals were characterized by chemical methods, EMX and neutron diffraction. It was possible to grow single crystals with a volume of up to 0.6 cm 3 and mosaic spread of less then 0.4 0 . (orig.) [de

  18. Single sheet metal oxides and hydroxides

    DEFF Research Database (Denmark)

    Huang, Lizhi

    The synthesis of layered double hydroxides (LDHs) provides a relatively easy and traditional way to build versatile chemical compounds with a rough control of the bulk structure. The delamination of LDHs to form their single host layers (2D nanosheets) and the capability to reassemble them offer......) Delamination of the LDHs structure (oxGRC12) with the formation of single sheet iron (hydr)oxide (SSI). (3) Assembly of the new 2D nanosheets layer by layer to achieve desired functionalities....

  19. New Physics in Single-Top Production

    CERN Document Server

    Kind, OM; The ATLAS collaboration

    2013-01-01

    In this presentation for TOP 2013 the latest results on searches of physics beyond the Standard Model using single-top signatures from CDF, CMS, D0 and ATLAS are collected. This includes searches for unknown resonances like W' or b*, measurements of the W helicity fractions and top polarisation in single-top events, as well as tests for CP violation, FCNC or anomalous weak couplings.

  20. Robotic single-site pelvic lymphadenectomy.

    Science.gov (United States)

    Tateo, Saverio; Nozza, Arrigo; Del Pezzo, Chiara; Mereu, Liliana

    2014-09-01

    To examine the feasibility of performing pelvic lymphadenectomy with robotic single site approach. Recent papers described the feasibility of robotic-single site hysterectomy [1-3] for benign and malign pathologies but only with the development of new single site 5mm instruments as the bipolar forceps, robotic single site platform can be safely utilized also for lymphadenectomy. A 65 year-old, multiparous patient with a body mass index of 22.5 and diagnosed with well differentiated adenocarcinoma of the endometrium underwent a robotic single-site peritoneal washing, total hysterectomy, bilateral adnexectomy and pelvic lymphadenectomy. The procedure was performed using the da Vinci Si Surgical System (Intuitive Surgical, Sunnyvale, CA) through a single 2,5 cm umbilical incision, with a multi-channel system and two single site robotic 5mm instruments. A 3-dimensional, HD 8.5mm endoscope and a 5mm accessory instrument were also utilized. Type I lymphonodes dissection for external iliac and obturator regions was performed [4]. Total operative time was 210 min; incision, trocar placement and docking time occurring in 12 min. Total console time was 183 min, estimated blood loss was 50 ml, no intra-operative or post-operative complications occurred. Hospital discharge occurred on post operative day 2 and total number of lymphnodes removed was 33. Difficulties in term of instrument's clashing and awkward motions have been encountered. Robotic single-site pelvic lymphadenectomy using bipolar forceps and monopolar hook is feasible. New developments are needed to improve surgical ergonomics and additional studies should be performed to explore possible benefits of this procedure. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Delayed repair of radiation induced clustered DNA damage: Friend or foe?

    Science.gov (United States)

    Eccles, Laura J.; O’Neill, Peter; Lomax, Martine E.

    2011-01-01

    A signature of ionizing radiation exposure is the induction of DNA clustered damaged sites, defined as two or more lesions within one to two helical turns of DNA by passage of a single radiation track. Clustered damage is made up of double strand breaks (DSB) with associated base lesions or abasic (AP) sites, and non-DSB clusters comprised of base lesions, AP sites and single strand breaks. This review will concentrate on the experimental findings of the processing of non-DSB clustered damaged sites. It has been shown that non-DSB clustered damaged sites compromise the base excision repair pathway leading to the lifetime extension of the lesions within the cluster, compared to isolated lesions, thus the likelihood that the lesions persist to replication and induce mutation is increased. In addition certain non-DSB clustered damaged sites are processed within the cell to form additional DSB. The use of E. coli to demonstrate that clustering of DNA lesions is the major cause of the detrimental consequences of ionizing radiation is also discussed. The delayed repair of non-DSB clustered damaged sites in humans can be seen as a “friend”, leading to cell killing in tumour cells or as a “foe”, resulting in the formation of mutations and genetic instability in normal tissue. PMID:21130102

  2. Delayed repair of radiation induced clustered DNA damage: Friend or foe?

    International Nuclear Information System (INIS)

    Eccles, Laura J.; O'Neill, Peter; Lomax, Martine E.

    2011-01-01

    A signature of ionizing radiation exposure is the induction of DNA clustered damaged sites, defined as two or more lesions within one to two helical turns of DNA by passage of a single radiation track. Clustered damage is made up of double strand breaks (DSB) with associated base lesions or abasic (AP) sites, and non-DSB clusters comprised of base lesions, AP sites and single strand breaks. This review will concentrate on the experimental findings of the processing of non-DSB clustered damaged sites. It has been shown that non-DSB clustered damaged sites compromise the base excision repair pathway leading to the lifetime extension of the lesions within the cluster, compared to isolated lesions, thus the likelihood that the lesions persist to replication and induce mutation is increased. In addition certain non-DSB clustered damaged sites are processed within the cell to form additional DSB. The use of E. coli to demonstrate that clustering of DNA lesions is the major cause of the detrimental consequences of ionizing radiation is also discussed. The delayed repair of non-DSB clustered damaged sites in humans can be seen as a 'friend', leading to cell killing in tumour cells or as a 'foe', resulting in the formation of mutations and genetic instability in normal tissue.

  3. Electrically Anisotropic Layered Perovskite Single Crystal

    KAUST Repository

    Li, Ting-You

    2016-04-01

    Organic-inorganic hybrid perovskites (OIHPs), which are promising materials for electronic and optoelectronic applications (1-10), have made into layered organic-inorganic hybrid perovskites (LOIHPs). These LOIHPs have been applied to thin-film transistors, solar cells and tunable wavelength phosphors (11-18). It is known that devices fabricated with single crystal exhibit the superior performance, which makes the growth of large-sized single crystals critical for future device applications (19-23). However, the difficulty in growing large-sized LOIHPs single crystal with superior electrical properties limits their practical applications. Here, we report a method to grow the centimeter-scaled LOIHP single crystal of [(HOC2H4NH3)2PbI4], demonstrating the potentials in mass production. After that, we reveal anisotropic electrical and optoelectronic properties which proved the carrier propagating along inorganic framework. The carrier mobility of in-inorganic-plane (in-plane) devices shows the average value of 45 cm2 V–1 s–1 which is about 100 times greater than the record of LOIHP devices (15), showing the importance of single crystal in device application. Moreover, the LOIHP single crystals show its ultra-short carrier lifetime of 42.7 ps and photoluminescence quantum efficiency (PLQE) of 25.4 %. We expect this report to be a start of LOIHPs for advanced applications in which the anisotropic properties are needed (24-25), and meets the demand of high-speed applications and fast-response applications.

  4. Structure of single-chain single crystals of isotactic polystyrene and their radiation resistance

    International Nuclear Information System (INIS)

    Bu Haishan; Cao Jie; Xu Shengyong; Zhang Ze

    1997-01-01

    The structure of the single-chain single crystals of isotactic polystyrene (i-PS) was investigated by electron diffraction (ED) and high resolution electron microscopy (HREM). The nano-scale single-chain single crystals were found to be very stable to electron irradiation. According to the unit cell of i-PS crystals, the reflection rings in ED pattern and the lattice fringes in HREM images could be indexed, but the lower-index diffractions were not found. It is proposed that the single-chain single crystals are very small, thus secondary electrons may be allowed to escape and radiation damage is highly reduced, and that there are less lower-index lattice planes in the single-chain single crystals to provide sufficient diffraction intensity for recording. HREM images can be achieved at room temperature in the case of single-chain single crystals because of its stability to electron irradiation, therefore, this might be a novel experimental approach to the study of crystal structure of macromolecules

  5. Work life and mental wellbeing of single and non-single working mothers in Scandinavia.

    Science.gov (United States)

    Bull, Torill; Mittelmark, Maurice B

    2009-08-01

    This study examined levels and predictors of mental wellbeing in Scandinavian working single and non-single mothers, with a special focus on financial stress, job characteristics and work-family conflict. The European Social Survey Round 2 (2005) provided questionnaire data from 73 single and 432 non-single working mothers in Denmark, Sweden and Norway. Respondents answered questions about the outcome variables life satisfaction, happiness, and positive affect, and predictor variables financial stress, job characteristics, work-family conflict, and social support. Hierarchical multiple regression was used to assess the relationships between predictor variables and mental wellbeing outcomes. Single working mothers scored significantly lower on life satisfaction and happiness, but not on positive affect, than did non-single mothers. Financial stress was higher in the single mother group. There were no significant differences in levels of enriching or stressful job characteristics, or in levels of social support. While financial stress and work-family conflict were important predictors in both groups, the relationship between financial stress and wellbeing was far stronger in the single mother group. Confidant support was a significant predictor only in the single mother group, and social participation only in the non-single mothers group. This study suggests that the Scandinavian welfare democracies have not yet been successful in relieving the financial pressure experienced by single working mothers. Development of efficient financial support systems should be prioritized. Ways to reduce work-family conflict in both single and non-single mothers in Scandinavia should also be given increased attention.

  6. Robotic-assisted single-port donor nephrectomy using the da Vinci single-site platform.

    Science.gov (United States)

    LaMattina, John C; Alvarez-Casas, Josue; Lu, Irene; Powell, Jessica M; Sultan, Samuel; Phelan, Michael W; Barth, Rolf N

    2018-02-01

    Although single-port donor nephrectomy offers improved cosmetic outcomes, technical challenges have limited its application to selected centers. Our center has performed over 400 single-port donor nephrectomies. The da Vinci single-site robotic platform was utilized in an effort to overcome the steric, visualization, ergonomic, and other technical limitations associated with the single-port approach. Food and Drug Administration device exemption was obtained. Selection criteria for kidney donation included body mass index da Vinci single-site platform. Our experience supported the safety of this approach but found that the technology added cost and complexity without tangible benefit. Development of articulating instruments, energy, and stapling devices will be necessary for increased application of robotic single-site surgery for donor nephrectomy. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Single-pulse and multi-pulse femtosecond laser damage of optical single films

    International Nuclear Information System (INIS)

    Yuan Lei; Zhao Yuan'an; He Hongbo; Shao Jianda; Fan Zhengxiu

    2006-01-01

    Laser-induced damage of a single 500 nm HfO 2 film and a single 500 nm ZrO 2 film were studied with single- and multi-pulse femtosecond laser. The laser-induced damage thresholds (LIDT) of both samples by the 1-on-1 method and the 1000-on-1 method were reported. It was discovered that the LIDT of the HfO 2 single film was higher than that of the ZrO 2 single film by both test methods, which was explained by simple Keldysh's multiphoton ionization theory. The LIDT of multi-pulse was lower than that of single-pulse for both samples as a result of accumulative effect. (authors)

  8. Technologies for Single-Cell Isolation.

    Science.gov (United States)

    Gross, Andre; Schoendube, Jonas; Zimmermann, Stefan; Steeb, Maximilian; Zengerle, Roland; Koltay, Peter

    2015-07-24

    The handling of single cells is of great importance in applications such as cell line development or single-cell analysis, e.g., for cancer research or for emerging diagnostic methods. This review provides an overview of technologies that are currently used or in development to isolate single cells for subsequent single-cell analysis. Data from a dedicated online market survey conducted to identify the most relevant technologies, presented here for the first time, shows that FACS (fluorescence activated cell sorting) respectively Flow cytometry (33% usage), laser microdissection (17%), manual cell picking (17%), random seeding/dilution (15%), and microfluidics/lab-on-a-chip devices (12%) are currently the most frequently used technologies. These most prominent technologies are described in detail and key performance factors are discussed. The survey data indicates a further increasing interest in single-cell isolation tools for the coming years. Additionally, a worldwide patent search was performed to screen for emerging technologies that might become relevant in the future. In total 179 patents were found, out of which 25 were evaluated by screening the title and abstract to be relevant to the field.

  9. Single Molecule Spectroscopy of Electron Transfer

    International Nuclear Information System (INIS)

    Holman, Michael; Zang, Ling; Liu, Ruchuan; Adams, David M.

    2009-01-01

    The objectives of this research are threefold: (1) to develop methods for the study electron transfer processes at the single molecule level, (2) to develop a series of modifiable and structurally well defined molecular and nanoparticle systems suitable for detailed single molecule/particle and bulk spectroscopic investigation, (3) to relate experiment to theory in order to elucidate the dependence of electron transfer processes on molecular and electronic structure, coupling and reorganization energies. We have begun the systematic development of single molecule spectroscopy (SMS) of electron transfer and summaries of recent studies are shown. There is a tremendous need for experiments designed to probe the discrete electronic and molecular dynamic fluctuations of single molecules near electrodes and at nanoparticle surfaces. Single molecule spectroscopy (SMS) has emerged as a powerful method to measure properties of individual molecules which would normally be obscured in ensemble-averaged measurement. Fluctuations in the fluorescence time trajectories contain detailed molecular level statistical and dynamical information of the system. The full distribution of a molecular property is revealed in the stochastic fluctuations, giving information about the range of possible behaviors that lead to the ensemble average. In the case of electron transfer, this level of understanding is particularly important to the field of molecular and nanoscale electronics: from a device-design standpoint, understanding and controlling this picture of the overall range of possible behaviors will likely prove to be as important as designing ia the ideal behavior of any given molecule.

  10. Technologies for Single-Cell Isolation

    Science.gov (United States)

    Gross, Andre; Schoendube, Jonas; Zimmermann, Stefan; Steeb, Maximilian; Zengerle, Roland; Koltay, Peter

    2015-01-01

    The handling of single cells is of great importance in applications such as cell line development or single-cell analysis, e.g., for cancer research or for emerging diagnostic methods. This review provides an overview of technologies that are currently used or in development to isolate single cells for subsequent single-cell analysis. Data from a dedicated online market survey conducted to identify the most relevant technologies, presented here for the first time, shows that FACS (fluorescence activated cell sorting) respectively Flow cytometry (33% usage), laser microdissection (17%), manual cell picking (17%), random seeding/dilution (15%), and microfluidics/lab-on-a-chip devices (12%) are currently the most frequently used technologies. These most prominent technologies are described in detail and key performance factors are discussed. The survey data indicates a further increasing interest in single-cell isolation tools for the coming years. Additionally, a worldwide patent search was performed to screen for emerging technologies that might become relevant in the future. In total 179 patents were found, out of which 25 were evaluated by screening the title and abstract to be relevant to the field. PMID:26213926

  11. Technologies for Single-Cell Isolation

    Directory of Open Access Journals (Sweden)

    Andre Gross

    2015-07-01

    Full Text Available The handling of single cells is of great importance in applications such as cell line development or single-cell analysis, e.g., for cancer research or for emerging diagnostic methods. This review provides an overview of technologies that are currently used or in development to isolate single cells for subsequent single-cell analysis. Data from a dedicated online market survey conducted to identify the most relevant technologies, presented here for the first time, shows that FACS (fluorescence activated cell sorting respectively Flow cytometry (33% usage, laser microdissection (17%, manual cell picking (17%, random seeding/dilution (15%, and microfluidics/lab-on-a-chip devices (12% are currently the most frequently used technologies. These most prominent technologies are described in detail and key performance factors are discussed. The survey data indicates a further increasing interest in single-cell isolation tools for the coming years. Additionally, a worldwide patent search was performed to screen for emerging technologies that might become relevant in the future. In total 179 patents were found, out of which 25 were evaluated by screening the title and abstract to be relevant to the field.

  12. Diamond-based single-photon emitters

    International Nuclear Information System (INIS)

    Aharonovich, I; Castelletto, S; Simpson, D A; Su, C-H; Greentree, A D; Prawer, S

    2011-01-01

    The exploitation of emerging quantum technologies requires efficient fabrication of key building blocks. Sources of single photons are extremely important across many applications as they can serve as vectors for quantum information-thereby allowing long-range (perhaps even global-scale) quantum states to be made and manipulated for tasks such as quantum communication or distributed quantum computation. At the single-emitter level, quantum sources also afford new possibilities in terms of nanoscopy and bio-marking. Color centers in diamond are prominent candidates to generate and manipulate quantum states of light, as they are a photostable solid-state source of single photons at room temperature. In this review, we discuss the state of the art of diamond-based single-photon emitters and highlight their fabrication methodologies. We present the experimental techniques used to characterize the quantum emitters and discuss their photophysical properties. We outline a number of applications including quantum key distribution, bio-marking and sub-diffraction imaging, where diamond-based single emitters are playing a crucial role. We conclude with a discussion of the main challenges and perspectives for employing diamond emitters in quantum information processing.

  13. Investigation on single carbon atom transporting through the single-walled carbon nanotube by MD simulation

    International Nuclear Information System (INIS)

    Ding Yinfeng; Zhang Zhibin; Ke Xuezhi; Zhu Zhiyuan; Zhu Dezhang; Wang Zhenxia; Xu Hongjie

    2005-01-01

    The single carbon atom transporting through the single-walled carbon nanotube has been studied by molecular-dynamics (MD) simulation. We got different trajectories of the carbon atom by changing the input parameters. The simulation results indicate that the single carbon atom with low energy can transport through the carbon nanotube under some input conditions and result in different trajectories being straight line or 'rosette' or circular. (authors)

  14. Controlled generation of a single Trichel pulse and a series of single Trichel pulses in air

    Science.gov (United States)

    Mizeraczyk, Jerzy; Berendt, Artur; Akishev, Yuri

    2018-04-01

    In this paper, a simple method for the controlled generation of a single Trichel pulse or a series of single Trichel pulses of a regulated repetition frequency in air is proposed. The concept of triggering a single Trichel pulse or a series of such pulses is based on the precise controlling the voltage inception of the negative corona, which can be accomplished through the use of a ramp voltage pulse or a series of such pulses with properly chosen ramp voltage pulse parameters (rise and fall times, and ramp voltage pulse repetition frequency). The proposal has been tested in experiments using a needle-to-plate electrode arrangement in air, and reproducible Trichel pulses (single or in a series) were obtained by triggering them with an appropriately designed voltage waveform. The proposed method and results obtained have been qualitatively analysed. The analysis provides guidance for designing the voltage ramp pulse in respect of the generation of a single Trichel pulse or a series of single Trichel pulses. The controlled generation of a single Trichel pulse or a series of such pulses would be a helpful research tool for the refined studies of the fundamental processes in a negative corona discharge in a single- (air is an example) and multi-phase gaseous fluids. The controlled generation of a single Trichel pulse or a series of Trichel pulses can also be attractive for those corona treatments which need manipulation of the electric charge and heat portions delivered by the Trichel pulses to the object.

  15. An automatic single channel analyzer based on single-chip microcomputer

    International Nuclear Information System (INIS)

    Yan Xuekun; Jia Mingchun; Zhang Yan; Liu Mingjian; Luo Ming

    2008-01-01

    The hardware and software of an automatic single channel analyzer based on AT89C51RC single-chip microcomputer is described in this paper. The equipment takes a method of channel-width-adjusting symmetrically, and makes use of single-chip microcomputer to control the two DAC0832 so as to adjust the discriminating threshold and channel-width automatically. As a result, the auto-measuring of the single channel analyzer is realized. Its circuit configuration is simple, and the uniformity of its channel-width is well, too. (authors)

  16. A novel high-efficiency single-mode quantum dot single photon source

    DEFF Research Database (Denmark)

    Gerard, J.M.; Gregersen, Niels; Nielsen, Torben Roland

    2008-01-01

    We present a novel single-mode single photon source exploiting the emission of a semiconductor quantum dot (QD) located inside a photonic wire. Besides an excellent coupling (>95%) of QD spontaneous emission to the fundamental guided mode [1], we show that a single photon collection efficiency...... above 80% within a 0.5 numerical aperture can be achieved using a bottom Bragg mirror and a tapering of the nanowire tip. Because this photon collection strategy does not exploit the Purcell effect, it could also be efficiently applied to broadband single photon emitters such as F-centers in diamond....

  17. Fast recognition of single molecules based on single-event photon statistics

    International Nuclear Information System (INIS)

    Dong Shuangli; Huang Tao; Liu Yuan; Wang Jun; Zhang Guofeng; Xiao Liantuan; Jia Suotang

    2007-01-01

    Mandel's Q parameter, which is determined from single-event photon statistics, provides an alternative way to recognize single molecules with fluorescence detection, other than the second-order correlation function. It is shown that the Q parameter of an assumed ideal double-molecule fluorescence with the same average photon number as that of the sample fluorescence can act as the criterion for single-molecule recognition. The influence of signal-to-background ratio and the error estimates for photon statistics are also presented. We have applied this method to ascertain single Cy5 dye molecules within hundreds of milliseconds

  18. Single-base resolution and long-coverage sequencing based on single-molecule nanomanipulation

    International Nuclear Information System (INIS)

    An Hongjie; Huang Jiehuan; Lue Ming; Li Xueling; Lue Junhong; Li Haikuo; Zhang Yi; Li Minqian; Hu Jun

    2007-01-01

    We show new approaches towards a novel single-molecule sequencing strategy which consists of high-resolution positioning isolation of overlapping DNA fragments with atomic force microscopy (AFM), subsequent single-molecule PCR amplification and conventional Sanger sequencing. In this study, a DNA labelling technique was used to guarantee the accuracy in positioning the target DNA. Single-molecule multiplex PCR was carried out to test the contamination. The results showed that the two overlapping DNA fragments isolated by AFM could be successfully sequenced with high quality and perfect contiguity, indicating that single-base resolution and long-coverage sequencing have been achieved simultaneously

  19. Coherent single-photon absorption by single emitters coupled to one-dimensional nanophotonic waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yuntian; Wubs, Martijn; Moerk, Jesper [DTU Fotonik, Department of Photonics Engineering, Oersteds Plads, DK-2800 Kgs Lyngby (Denmark); Koenderink, A Femius, E-mail: yche@fotonik.dtu.dk [Center for Nanophotonics, FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, 1098 XG Amsterdam (Netherlands)

    2011-10-15

    We study the dynamics of single-photon absorption by a single emitter coupled to a one-dimensional waveguide that simultaneously provides channels for spontaneous emission (SE) decay and a channel for the input photon. We have developed a time-dependent theory that allows us to specify any input single-photon wavepacket guided by the waveguide as the initial condition, and calculate the excitation probability of the emitter, as well as the time evolution of the transmitted and reflected fields. For single-photon wavepackets with a Gaussian spectrum and temporal shape, we obtain analytical solutions for the dynamics of absorption, with maximum atomic excitation {approx}40%. We furthermore propose a terminated waveguide to aid the single-photon absorption. We found that for an emitter placed at an optimal distance from the termination, the maximum atomic excitation due to an incident single-photon wavepacket can exceed 70%. This high value is a direct consequence of the high SE {beta}-factor for emission into the waveguide. Finally, we have also explored whether waveguide dispersion could aid single-photon absorption by pulse shaping. For a Gaussian input wavepacket, we found that the absorption efficiency can be improved by a further 4% by engineering the dispersion. Efficient single-photon absorption by a single emitter has potential applications in quantum communication and quantum computation. (paper)

  20. Single DNA denaturation and bubble dynamics

    DEFF Research Database (Denmark)

    Metzler, Ralf; Ambjörnsson, Tobias; Hanke, Andreas

    2009-01-01

    While the Watson-Crick double-strand is the thermodynamically stable state of DNA in a wide range of temperature and salt conditions, even at physiological conditions local denaturation bubbles may open up spontaneously due to thermal activation. By raising the ambient temperature, titration......, or by external forces in single molecule setups bubbles proliferate until full denaturation of the DNA occurs. Based on the Poland-Scheraga model we investigate both the equilibrium transition of DNA denaturation and the dynamics of the denaturation bubbles with respect to recent single DNA chain experiments...... for situations below, at, and above the denaturation transition. We also propose a new single molecule setup based on DNA constructs with two bubble zones to measure the bubble coalescence and extract the physical parameters relevant to DNA breathing. Finally we consider the interplay between denaturation...

  1. Autonomous calibration of single spin qubit operations

    Science.gov (United States)

    Frank, Florian; Unden, Thomas; Zoller, Jonathan; Said, Ressa S.; Calarco, Tommaso; Montangero, Simone; Naydenov, Boris; Jelezko, Fedor

    2017-12-01

    Fully autonomous precise control of qubits is crucial for quantum information processing, quantum communication, and quantum sensing applications. It requires minimal human intervention on the ability to model, to predict, and to anticipate the quantum dynamics, as well as to precisely control and calibrate single qubit operations. Here, we demonstrate single qubit autonomous calibrations via closed-loop optimisations of electron spin quantum operations in diamond. The operations are examined by quantum state and process tomographic measurements at room temperature, and their performances against systematic errors are iteratively rectified by an optimal pulse engineering algorithm. We achieve an autonomous calibrated fidelity up to 1.00 on a time scale of minutes for a spin population inversion and up to 0.98 on a time scale of hours for a single qubit π/2 -rotation within the experimental error of 2%. These results manifest a full potential for versatile quantum technologies.

  2. Handbook of Single-Molecule Biophysics

    CERN Document Server

    Hinterdorfer, Peter

    2009-01-01

    The last decade has seen the development of a number of novel biophysical methods that allow the manipulation and study of individual biomolecules. The ability to monitor biological processes at this fundamental level of sensitivity has given rise to an improved understanding of the underlying molecular mechanisms. Through the removal of ensemble averaging, distributions and fluctuations of molecular properties can be characterized, transient intermediates identified, and catalytic mechanisms elucidated. By applying forces on biomolecules while monitoring their activity, important information can be obtained on how proteins couple function to structure. The Handbook of Single-Molecule Biophysics provides an introduction to these techniques and presents an extensive discussion of the new biological insights obtained from them. Coverage includes: Experimental techniques to monitor and manipulate individual biomolecules The use of single-molecule techniques in super-resolution and functional imaging Single-molec...

  3. THE BERTRAND MODEL OF THE SINGLE MARKET

    Directory of Open Access Journals (Sweden)

    Vadasan Ioana

    2010-12-01

    Full Text Available Starting with the signification of the rationality hypothesis when the agent’s contentment is directly affected by the other agents’ decisions, the theory of games defines solutions for solving different situations of conflict. The economic actors have different behaviours of the Single Market. Oligopoly strategic behaviours were analysed by the Bertrand model. The two types revealed in the work show that strategic interactions are sensitive to the companies’ features, products and markets. Regarding the situation when we have an oligopoly competition, the companies make interdependent decisions in the environment affected by risk and uncertainty of the Single Market. For this reason it is an opportunity to study the structure of oligopoly type of of the Single Market with the aid of non – cooperative games.

  4. Torque Measurement at the Single Molecule Level

    Science.gov (United States)

    Forth, Scott; Sheinin, Maxim Y.; Inman, James; Wang, Michelle D.

    2017-01-01

    Methods for exerting and measuring forces on single molecules have revolutionized the study of the physics of biology. However, it is often the case that biological processes involve rotation or torque generation, and these parameters have been more difficult to access experimentally. Recent advances in the single molecule field have led to the development of techniques which add the capability of torque measurement. By combining force, displacement, torque, and rotational data, a more comprehensive description of the mechanics of a biomolecule can be achieved. In this review, we highlight a number of biological processes for which torque plays a key mechanical role. We describe the various techniques that have been developed to directly probe the torque experienced by a single molecule, and detail a variety of measurements made to date using these new technologies. We conclude by discussing a number of open questions and propose systems of study which would be well suited for analysis with torsional measurement techniques. PMID:23541162

  5. Single-particle Schroedinger fluid. I. Formulation

    International Nuclear Information System (INIS)

    Kan, K.K.; Griffin, J.J.

    1976-01-01

    The problem of a single quantal particle moving in a time-dependent external potential well is formulated specifically to emphasize and develop the fluid dynamical aspects of the matter flow. This idealized problem, the single-particle Schroedinger fluid, is shown to exhibit already a remarkably rich variety of fluid dynamical features, including compressible flow and line vortices. It provides also a sufficient framework to encompass simultaneously various simplified fluidic models for nuclei which have earlier been postulated on an ad hoc basis, and to illuminate their underlying restrictions. Explicit solutions of the single-particle Schroedinger fluid problem are studied in the adiabatic limit for their mathematical and physical implications (especially regarding the collective kinetic energy). The basic generalizations for extension of the treatment to the many-body Schroedinger fluid are set forth

  6. On theory of single-molecule transistor

    International Nuclear Information System (INIS)

    Tran Tien Phuc

    2009-01-01

    The results of the study on single-molecule transistor are mainly investigated in this paper. The structure of constructed single-molecule transistor is similar to a conventional MOSFET. The conductive channel of the transistors is a single-molecule of halogenated benzene derivatives. The chemical simulation software CAChe was used to design and implement for the essential parameter of the molecules utilized as the conductive channel. The GUI of Matlab has been built to design its graphical interface, calculate and plot the output I-V characteristic curves for the transistor. The influence of temperature, length and width of the conductive channel, and gate voltage is considered. As a result, the simulated curves are similar to the traditional MOSFET's. The operating temperature range of the transistors is wider compared with silicon semiconductors. The supply voltage for transistors is only about 1 V. The size of transistors in this research is several nanometers.

  7. Acoustic effects of single electrostatic discharges

    International Nuclear Information System (INIS)

    Orzech, Łukasz

    2015-01-01

    Electric discharges, depending on their character, can emit different types of energy, resulting in different effects. Single electrostatic discharges besides generation of electromagnetic pulses are also the source of N acoustic waves. Their specified parameters depending on amount of discharging charge enable determination of value of released charge in a function of acoustic descriptor (e.g. acoustic pressure). Presented approach is the basics of acoustic method for measurement of single electrostatic discharges, enabling direct and contactless measurement of value of charge released during ESD. Method for measurement of acoustic effect of impact of a single electrostatic discharge on the environment in a form of pressure shock wave and examples of acoustic descriptors in a form of equation Q=f(p a ) are described. The properties of measuring system as well as the results of regression static analyses used to determine the described relationships are analysed in details. (paper)

  8. Microplastic relaxations of single and polycrystalline molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Pichl, W.; Weiss, B. [Wien Univ. (Austria). Inst. fuer Materialphysik; Chen, D.L.

    1998-05-01

    The microplasticity of high-purity molybdenum single crystals and of Mo polycrystals of technical purity has been investigated by relaxation step tests in uniaxial compression. A new model for the evaluation of relaxation tests in the microplastic range of b.c.c metals is presented which takes into account the decrease of the mobile dislocation density due to exhaustion of non-screw dislocations. The model allows an independent determination of the activation volume and of the microstructure parameters controlling dislocation exhaustion. The results indicate that in the high-purity single crystals the deformation rate is controlled by interactions of non-screw dislocations with the grown-in network. In the polycrystals additional interactions with impurity atoms seem to occur. In the single crystals the activity and subsequent exhaustion of two different glide systems was observed, followed by a gradual onset of screw dislocation motion. (orig.) 26 refs.

  9. Solid-state single-photon emitters

    Science.gov (United States)

    Aharonovich, Igor; Englund, Dirk; Toth, Milos

    2016-10-01

    Single-photon emitters play an important role in many leading quantum technologies. There is still no 'ideal' on-demand single-photon emitter, but a plethora of promising material systems have been developed, and several have transitioned from proof-of-concept to engineering efforts with steadily improving performance. Here, we review recent progress in the race towards true single-photon emitters required for a range of quantum information processing applications. We focus on solid-state systems including quantum dots, defects in solids, two-dimensional hosts and carbon nanotubes, as these are well positioned to benefit from recent breakthroughs in nanofabrication and materials growth techniques. We consider the main challenges and key advantages of each platform, with a focus on scalable on-chip integration and fabrication of identical sources on photonic circuits.

  10. Single-particle dispersion in compressible turbulence

    Science.gov (United States)

    Zhang, Qingqing; Xiao, Zuoli

    2018-04-01

    Single-particle dispersion statistics in compressible box turbulence are studied using direct numerical simulation. Focus is placed on the detailed discussion of effects of the particle Stokes number and turbulent Mach number, as well as the forcing type. When solenoidal forcing is adopted, it is found that the single-particle dispersion undergoes a transition from the ballistic regime at short times to the diffusive regime at long times, in agreement with Taylor's particle dispersion argument. The strongest dispersion of heavy particles is announced when the Stokes number is of order 1, which is similar to the scenario in incompressible turbulence. The dispersion tends to be suppressed as the Mach number increases. When hybrid solenoidal and compressive forcing at a ratio of 1/2 is employed, the flow field shows apparent anisotropic property, characterized by the appearance of large shock wave structures. Accordingly, the single-particle dispersion shows extremely different behavior from the solenoidal forcing case.

  11. Single Photon Sources in Silicon Carbide

    International Nuclear Information System (INIS)

    Brett Johnson

    2014-01-01

    Single photon sources in semiconductors are highly sought after as they constitute the building blocks of a diverse range of emerging technologies such as integrated quantum information processing, quantum metrology and quantum photonics. In this presentation, we show the first observation of single photon emission from deep level defects in silicon carbide (SiC). The single photon emission is photo-stable at room temperature and surprisingly bright. This represents an exciting alternative to diamond color centers since SiC possesses well-established growth and device engineering protocols. The defect is assigned to the carbon vacancy-antisite pair which gives rise to the AB photoluminescence lines. We discuss its photo-physical properties and their fabrication via electron irradiation. Preliminary measurements on 3C SiC nano-structures will also be discussed. (author)

  12. Theory of Single Point Incremental Forming

    DEFF Research Database (Denmark)

    Martins, P.A.F.; Bay, Niels; Skjødt, Martin

    2008-01-01

    This paper presents a closed-form theoretical analysis modelling the fundamentals of single point incremental forming and explaining the experimental and numerical results available in the literature for the past couple of years. The model is based on membrane analysis with bi-directional in-plan......-plane contact friction and is focused on the extreme modes of deformation that are likely to be found in single point incremental forming processes. The overall investigation is supported by experimental work performed by the authors and data retrieved from the literature.......This paper presents a closed-form theoretical analysis modelling the fundamentals of single point incremental forming and explaining the experimental and numerical results available in the literature for the past couple of years. The model is based on membrane analysis with bi-directional in...

  13. Single molecule transcription profiling with AFM

    International Nuclear Information System (INIS)

    Reed, Jason; Mishra, Bud; Pittenger, Bede; Magonov, Sergei; Troke, Joshua; Teitell, Michael A; Gimzewski, James K

    2007-01-01

    Established techniques for global gene expression profiling, such as microarrays, face fundamental sensitivity constraints. Due to greatly increasing interest in examining minute samples from micro-dissected tissues, including single cells, unorthodox approaches, including molecular nanotechnologies, are being explored in this application. Here, we examine the use of single molecule, ordered restriction mapping, combined with AFM, to measure gene transcription levels from very low abundance samples. We frame the problem mathematically, using coding theory, and present an analysis of the critical error sources that may serve as a guide to designing future studies. We follow with experiments detailing the construction of high density, single molecule, ordered restriction maps from plasmids and from cDNA molecules, using two different enzymes, a result not previously reported. We discuss these results in the context of our calculations

  14. Early Loaded Single Implant Reinforced Mandibular Overdenture

    Directory of Open Access Journals (Sweden)

    K. Nischal

    2016-01-01

    Full Text Available Rehabilitating atrophied mandible with two-implant supported denture is a common treatment modality for implant retained removable overdenture in mandible. This paper aims to design a treatment modality where single implant reinforced overdenture is fabricated for a severely atrophied mandibular ridge with early loading protocol. Results of studies have shown that a single implant mandibular overdenture significantly increases the satisfaction and quality of life of patients with edentulism. Midline fracture of the prosthesis is the most common complication related to single implant and two-implant retained mandibular overdentures. To manage such complication, a thin metal mesh is used to reinforce the overdenture and also to make the prostheses lighter and cost effective as compared to conventional cast metal framework.

  15. Stretching single fibrin fibers hampers their lysis.

    Science.gov (United States)

    Li, Wei; Lucioni, Tomas; Li, Rongzhong; Bonin, Keith; Cho, Samuel S; Guthold, Martin

    2017-09-15

    Blood clots, whose main structural component is a mesh of microscopic fibrin fibers, experience mechanical strain from blood flow, clot retraction and interactions with platelets and other cells. We developed a transparent, striated and highly stretchable substrate made from fugitive glue (a styrenic block copolymer) to investigate how mechanical strain affects lysis of single, suspended fibrin fibers. In this suspended fiber assay, lysis manifested itself by fiber elongation, thickening (disassembly), fraying and collapse. Stretching single fibrin fibers significantly hampered their lysis. This effect was seen in uncrosslinked and crosslinked fibers. Crosslinking (without stretching) also hampered single fiber lysis. Our data suggest that strain is a novel mechanosensitive factor that regulates blood clot dissolution (fibrinolysis) at the single fiber level. At the molecular level of single fibrin molecules, strain may distort, or hinder access to, plasmin cleavage sites and thereby hamper lysis. Fibrin fibers are the major structural component of a blood clot. We developed a highly stretchable substrate made from fugitive glue and a suspended fibrin fiber lysis assay to investigate the effect of stretching on single fibrin fibers lysis. The key findings from our experiments are: 1) Fibers thicken and elongate upon lysis; 2) stretching strongly reduces lysis; 3) this effect is more pronounced for uncrosslinked fibers; and 4) stretching fibers has a similar effect on reducing lysis as crosslinking fibers. At the molecular level, strain may distort plasmin cleavage sites, or restrict access to those sites. Our results suggest that strain may be a novel mechanobiological factor that regulates fibrinolysis. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Laparoendoscopic single site in pelvic surgery

    Science.gov (United States)

    Sanchez-Salas, Rafael; Clavijo, Rafael; Barret, Eric; Sotelo, Rene

    2012-01-01

    Laparoendoscopic single site (LESS) has recently gained momentum as feasible techniques for minimal access surgery. Our aim is to describe the current status of laparoendoscopic single site (LESS) in pelvic surgery. A comprehensive revision of the literature in LESS pelvic surgery was performed. References for this manuscript were obtained by performing a review of the available literature in PubMed from 01-01-01 to 30-11-11. References outside the search period were obtained selected manuscript΄s bibliography. Search terms included: pelvic anatomy, less in gynecology, single port colectomy, urological less, single port, single site, NOTES, LESS and single incision. 314 manuscripts were initially identified. Out of these, 46 manuscripts were selected based in their pelvic anatomy or surgical content; including experimental experience, clinical series and literature reviews. LESS drastically limit the surgeon's ability to perform in the operative field and the latter becomes hardened by the lack of space in anatomical location like the pelvis. Potential advantages of LESS are gained with the understanding that the surgical procedure is more technically challenging. Pelvic surgical procedures related to colorectal surgery, gynecology and urology have been performed with LESS technique and information available is mostly represented by case reports and short case series. Comparative series remain few. LESS pelvic surgery remain in its very beginning and due to the very specific anatomical conditions further development of LESS surgery in the mentioned area can be clearly be facilitated by using robotic technology. Standardization ad reproducibility of techniques are mandatory to further develop LESS in the surgical arena.. PMID:22557719

  17. Laparoendoscopic single site in pelvic surgery

    Directory of Open Access Journals (Sweden)

    Rafael Sanchez-Salas

    2012-01-01

    Full Text Available Laparoendoscopic single site (LESS has recently gained momentum as feasible techniques for minimal access surgery. Our aim is to describe the current status of laparoendoscopic single site (LESS in pelvic surgery. A comprehensive revision of the literature in LESS pelvic surgery was performed. References for this manuscript were obtained by performing a review of the available literature in PubMed from 01-01-01 to 30-11-11. References outside the search period were obtained selected manuscript΄s bibliography. Search terms included: pelvic anatomy, less in gynecology, single port colectomy, urological less, single port, single site, NOTES, LESS and single incision. 314 manuscripts were initially identified. Out of these, 46 manuscripts were selected based in their pelvic anatomy or surgical content; including experimental experience, clinical series and literature reviews. LESS drastically limit the surgeon′s ability to perform in the operative field and the latter becomes hardened by the lack of space in anatomical location like the pelvis. Potential advantages of LESS are gained with the understanding that the surgical procedure is more technically challenging. Pelvic surgical procedures related to colorectal surgery, gynecology and urology have been performed with LESS technique and information available is mostly represented by case reports and short case series. Comparative series remain few. LESS pelvic surgery remain in its very beginning and due to the very specific anatomical conditions further development of LESS surgery in the mentioned area can be clearly be facilitated by using robotic technology. Standardization ad reproducibility of techniques are mandatory to further develop LESS in the surgical arena..

  18. Dual color single particle tracking via nanobodies

    International Nuclear Information System (INIS)

    Albrecht, David; Winterflood, Christian M; Ewers, Helge

    2015-01-01

    Single particle tracking is a powerful tool to investigate the function of biological molecules by following their motion in space. However, the simultaneous tracking of two different species of molecules is still difficult to realize without compromising the length or density of trajectories, the localization accuracy or the simplicity of the assay. Here, we demonstrate a simple dual color single particle tracking assay using small, bright, high-affinity labeling via nanobodies of accessible targets with widely available instrumentation. We furthermore apply a ratiometric step-size analysis method to visualize differences in apparent membrane viscosity. (paper)

  19. Friction stir welding of single crystal aluminium

    DEFF Research Database (Denmark)

    Fonda, Richard Warren; Wert, John A.; Reynolds, A.P.

    2007-01-01

    Friction stir welds were prepared in different orientations in an aluminium single crystal. The welds were quenched to preserve the microstructure surrounding the tool and then electron backscattered diffraction was used to reveal the generation of grain boundaries and the evolution...... of crystallographic texture around the tool in each weld. The extent of both dynamic recrystallisation and conventional recrystallisation varied considerably as a function of weld orientation. As the base plate begins to interact with the deformation field surrounding the tool, regions of the single crystal rotate...

  20. Valve system incorporating single failure protection logic

    Science.gov (United States)

    Ryan, Rodger; Timmerman, Walter J. H.

    1980-01-01

    A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.

  1. Single Molecule Biophysics Experiments and Theory

    CERN Document Server

    Komatsuzaki, Tamiki; Takahashi, Satoshi; Yang, Haw; Silbey, Robert J; Rice, Stuart A; Dinner, Aaron R

    2011-01-01

    Discover the experimental and theoretical developments in optical single-molecule spectroscopy that are changing the ways we think about molecules and atoms The Advances in Chemical Physics series provides the chemical physics field with a forum for critical, authoritative evaluations of advances in every area of the discipline. This latest volume explores the advent of optical single-molecule spectroscopy, and how atomic force microscopy has empowered novel experiments on individual biomolecules, opening up new frontiers in molecular and cell biology and leading to new theoretical approaches

  2. Single-Trial Inference on Visual Attention

    DEFF Research Database (Denmark)

    Dyrholm, Mads; Kyllingsbæk, Søren; Vangkilde, Signe Allerup

    2011-01-01

    In this paper we take a step towards single-trial behavioral modeling within a Theory of Visual Attention (TVA). In selective attention tasks, such as the Partial Report paradigm, the subject is asked to ignore distractors and only report stimuli that belong to the target class. Nothing about...... Report trial. This result retrodicts a latent attentional state of the subject using the observed response from that particular trial and thus differs from other predictions made with TVA which are based on expected values of observed variables. We show an example of the result in single-trial analysis...

  3. Ghost imaging with a single detector

    International Nuclear Information System (INIS)

    Bromberg, Yaron; Katz, Ori; Silberberg, Yaron

    2009-01-01

    We experimentally demonstrate pseudothermal ghost imaging and ghost diffraction using only a single detector. We achieve this by replacing the high-resolution detector of the reference beam with a computation of the propagating field, following a recent proposal by Shapiro [Phys. Rev. A 78, 061802(R) (2008)]. Since only a single detector is used, this provides experimental evidence that pseudothermal ghost imaging does not rely on nonlocal quantum correlations. In addition, we show the depth-resolving capability of this ghost imaging technique.

  4. Single-particle Glauber matrix elements

    International Nuclear Information System (INIS)

    Oset, E.; Strottman, D.

    1983-01-01

    The single-particle matrix elements of the Glauber profile function are tabulated for harmonic oscillator single-particle wave functions. The tables are presented in such a manner as to be applicable if the hadron--nucleon elementary scattering amplitude is specified by either a partial wave expansion or a Gaussian in momentum transfer squared. The table is complete through the 1 g/sub 9/2/ orbital and contains entries for the 3s/sub 1/2/ orbital for use if realistic wave functions are expanded in terms of harmonic oscillator functions

  5. Resolving single bubble sonoluminescence flask width

    OpenAIRE

    Arakeri, Vijay H

    1998-01-01

    Single bubble sonoluminescence (SBSL), first studied and observed by Gaitan et al., is the of light emission from a single gas bubble trapped at the pressure maximum of a resonant sound field in a liquid medium, generally water. One of the most striking aspects of SBSL was the estimated optical flash width being less than 50 picoseconds (ps)3; this upper estimate was based on the relative response of a SBSL flash in comparison to a 34 ps laser pulse using a microchannel platephotomultiplier ...

  6. From Single Market to Economic Union

    DEFF Research Database (Denmark)

    Bartalevich, Dzmitry

    2014-01-01

    Book review of: From Single Market to Economic Union: Essays in Memory of John A. Usher / edited by N.N. Shuibhne and L.W. Gormley (Oxford: Oxford University Press, 2012, ISBN 9780199695706); viii + 431pp., £75.00 hb.......Book review of: From Single Market to Economic Union: Essays in Memory of John A. Usher / edited by N.N. Shuibhne and L.W. Gormley (Oxford: Oxford University Press, 2012, ISBN 9780199695706); viii + 431pp., £75.00 hb....

  7. Multiple and single snapshot compressive beamforming

    DEFF Research Database (Denmark)

    Gerstoft, Peter; Xenaki, Angeliki; Mecklenbrauker, Christoph F.

    2015-01-01

    and multiple snapshots. CS does not require inversion of the data covariance matrix and thus works well even for a single snapshot where it gives higher resolution than conventional beamforming. For multiple snapshots, CS outperforms conventional high-resolution methods even with coherent arrivals and at low......-lagged superposition of source amplitudes at all hypothetical DOAs. Regularizing with an ‘1-norm constraint renders the problem solvable with convex optimization, and promoting sparsity gives highresolution DOA maps. Here the sparse source distribution is derived using maximum a posteriori estimates for both single...

  8. Single beam pass migmacell method and apparatus

    International Nuclear Information System (INIS)

    Maglich, B.C.; Nering, J.E.; Mazarakis, M.G.; Miller, R.A.

    1976-01-01

    The invention provides improvements in migmacell apparatus and method by dispensing with the need for metastable confinement of injected molecular ions for multiple precession periods. Injected molecular ions undergo a 'single pass' through the reaction volume. By preconditioning the injected beam such that it contains a population distribution of molecules in higher vibrational states than in the case of a normal distribution, injected molecules in the single pass exper-ience collisionless dissociation in the migmacell under magnetic influence, i.e., so-called Lorentz dissociation. Dissociationions then form atomic migma

  9. Continuum mechanics of single-substance bodies

    CERN Document Server

    Eringen, A Cemal

    1975-01-01

    Continuum Physics, Volume II: Continuum Mechanics of Single-Substance Bodies discusses the continuum mechanics of bodies constituted by a single substance, providing a thorough and precise presentation of exact theories that have evolved during the past years. This book consists of three parts-basic principles, constitutive equations for simple materials, and methods of solution. Part I of this publication is devoted to a discussion of basic principles irrespective of material geometry and constitution that are valid for all kinds of substances, including composites. The geometrical notions, k

  10. Thousand-fold enhancement of single-molecule fluorescence near a single gold nanorod

    NARCIS (Netherlands)

    Yuan, H.; Khatua, S.; Zijlstra, P.; Yorulmaz, M.; Orrit, M.

    2013-01-01

    Single molecules: Large enhancements of single-molecule fluorescence up to 1100 times by using synthesized gold nanorods are reported (see picture). This high enhancement is achieved by selecting a dye with its adsorption and emission close to the surface plasmon resonance of the gold nanorods

  11. Self-templated synthesis of single-crystal and single-domain ferroelectric nanoplates

    KAUST Repository

    Chao, Chunying; Ren, Zhaohui; Zhu, Yihan; Xiao, Zhen; Liu, Zhenya; Xú , Gang; Mai, Jiangquan; Li, Xiang; Shen, Ge; Han, Gaorong

    2012-01-01

    Free-standing single-crystal PbTiO 3 nanoplates (see picture) were synthesized by a facile hydrothermal method. A "self-templated" crystal growth is presumed to lead to the formation of the PbTiO 3 nanoplates, which have ferroelectric single

  12. Sex Differences in Parenting Behaviors in Single-Mother and Single-Father Households

    Science.gov (United States)

    Dufur, Mikaela J.; Howell, Nyssa C.; Downey, Douglas B.; Ainsworth, James W.; Lapray, Alice J.

    2010-01-01

    Research on family structure has led some to claim that sex-based parenting differences exist. But if such differences exist in single-parent families, the absence of a second parent rather than specific sex-typed parenting might explain them. We examine differences in mothering and fathering behavior in single-parent households, where number of…

  13. Pervasive within-Mitochondrion Single-Nucleotide Variant Heteroplasmy as Revealed by Single-Mitochondrion Sequencing

    Directory of Open Access Journals (Sweden)

    Jacqueline Morris

    2017-12-01

    Full Text Available Summary: A number of mitochondrial diseases arise from single-nucleotide variant (SNV accumulation in multiple mitochondria. Here, we present a method for identification of variants present at the single-mitochondrion level in individual mouse and human neuronal cells, allowing for extremely high-resolution study of mitochondrial mutation dynamics. We identified extensive heteroplasmy between individual mitochondrion, along with three high-confidence variants in mouse and one in human that were present in multiple mitochondria across cells. The pattern of variation revealed by single-mitochondrion data shows surprisingly pervasive levels of heteroplasmy in inbred mice. Distribution of SNV loci suggests inheritance of variants across generations, resulting in Poisson jackpot lines with large SNV load. Comparison of human and mouse variants suggests that the two species might employ distinct modes of somatic segregation. Single-mitochondrion resolution revealed mitochondria mutational dynamics that we hypothesize to affect risk probabilities for mutations reaching disease thresholds. : Morris et al. use independent sequencing of multiple individual mitochondria from mouse and human brain cells to show high pervasiveness of mutations. The mutations are heteroplasmic within single mitochondria and within and between cells. These findings suggest mechanisms by which mutations accumulate over time, resulting in mitochondrial dysfunction and disease. Keywords: single mitochondrion, single cell, human neuron, mouse neuron, single-nucleotide variation

  14. 34 CFR 403.81 - How must funds be used under the Single Parents, Displaced Homemakers, and Single Pregnant Women...

    Science.gov (United States)

    2010-07-01

    ..., Displaced Homemakers, and Single Pregnant Women Program? 403.81 Section 403.81 Education Regulations of the... Secretary Assist Under the Basic Programs? Single Parents, Displaced Homemakers, and Single Pregnant Women... individuals who are single parents, displaced homemakers, or single pregnant women only to— (a) Provide...

  15. 34 CFR 403.82 - In what settings may the Single Parents, Displaced Homemakers, and Single Pregnant Women Program...

    Science.gov (United States)

    2010-07-01

    ... Homemakers, and Single Pregnant Women Program be offered? 403.82 Section 403.82 Education Regulations of the... Secretary Assist Under the Basic Programs? Single Parents, Displaced Homemakers, and Single Pregnant Women Program § 403.82 In what settings may the Single Parents, Displaced Homemakers, and Single Pregnant Women...

  16. Levitation With a Single Acoustic Driver

    Science.gov (United States)

    Barmatz, M. B.; Gaspar, M. S.; Allen, J. L.

    1986-01-01

    Pair of reports describes acoustic-levitation systems in which only one acoustic resonance mode excited, and only one driver needed. Systems employ levitation chambers of rectangular and cylindrical geometries. Reports first describe single mode concept and indicate which modes used to levitate sample without rotation. Reports then describe systems in which controlled rotation of sample introduced.

  17. The Utility of Single Subject Design Research

    Science.gov (United States)

    Bennett, Kyle D.

    2016-01-01

    Single subject design (SSD) research is a quantitative approach used to investigate basic and applied research questions. It has been used for decades to examine issues of social importance such as those related to general and special education strategies, therapeutic approaches in mental health, community health practices, safety, and business…

  18. 78 FR 38843 - Single Application Option

    Science.gov (United States)

    2013-06-28

    ... Application Option AGENCY: U.S. Copyright Office, Library of Congress. ACTION: Interim final rule. SUMMARY: The U.S. Copyright Office is amending its regulations on an interim basis in order to establish a new... an additional option for individual authors/claimants registering a single (one) work that is not a...

  19. Destructive Single-Event Effects in Diodes

    Science.gov (United States)

    Casey, Megan C.; Lauenstein, Jean-Marie; Campola, Michael J.; Wilcox, Edward P.; Phan, Anthony M.; Label, Kenneth A.

    2017-01-01

    In this work, we discuss the observed single-event effects in a variety of types of diodes. In addition, we conduct failure analysis on several Schottky diodes that were heavy-ion irradiated. High- and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images are used to identify and describe the failure locations.

  20. Nuclear structure and the single charge exchange

    International Nuclear Information System (INIS)

    Oset, E.; Strottman, D.

    1979-01-01

    The influence of nuclear structure on meson-induced single-charge-exchange reactions on light nuclei is discussed within the context of the Glauber approximation. Selection rules which are expected to be approximately obeyed in elastic and inelastic pion and kaon scattering are proposed. Theoretical predictions are presented for (π + ,π 0 ) and (K + ,K 0 ) reactions on 13 C. 14 figures

  1. Ballistic Limit Equation for Single Wall Titanium

    Science.gov (United States)

    Ratliff, J. M.; Christiansen, Eric L.; Bryant, C.

    2009-01-01

    Hypervelocity impact tests and hydrocode simulations were used to determine the ballistic limit equation (BLE) for perforation of a titanium wall, as a function of wall thickness. Two titanium alloys were considered, and separate BLEs were derived for each. Tested wall thicknesses ranged from 0.5mm to 2.0mm. The single-wall damage equation of Cour-Palais [ref. 1] was used to analyze the Ti wall's shielding effectiveness. It was concluded that the Cour-Palais single-wall equation produced a non-conservative prediction of the ballistic limit for the Ti shield. The inaccurate prediction was not a particularly surprising result; the Cour-Palais single-wall BLE contains shield material properties as parameters, but it was formulated only from tests of different aluminum alloys. Single-wall Ti shield tests were run (thicknesses of 2.0 mm, 1.5 mm, 1.0 mm, and 0.5 mm) on Ti 15-3-3-3 material custom cut from rod stock. Hypervelocity impact (HVI) tests were used to establish the failure threshold empirically, using the additional constraint that the damage scales with impact energy, as was indicated by hydrocode simulations. The criterion for shield failure was defined as no detached spall from the shield back surface during HVI. Based on the test results, which confirmed an approximately energy-dependent shield effectiveness, the Cour-Palais equation was modified.

  2. Single-Sex Schooling Gets New Showcase

    Science.gov (United States)

    McNeil, Michele

    2008-01-01

    Single-sex classrooms and schools are common in private education and have emerged as popular options in urban public school districts, such as New York City, particularly as a strategy for raising the achievement of African-American boys. South Carolina is at the forefront of implementing such programs statewide. Ninety-seven schools in South…

  3. Theorising Practice in Single-Sex Work.

    Science.gov (United States)

    Tett, Lyn

    1996-01-01

    The practice of adult educators in single-sex settings is directed by "theories-in-use" about the social construction of gender, such as gender is culturally constructed but people internalize gender stereotypes; gender stereotypes can be challenged and changed; and power to define gender roles lies in patriarchy, but it can be contested…

  4. Number of Single-Sex Schools Growing

    Science.gov (United States)

    Barak, Tal

    2004-01-01

    The U.S. Department of Education's office for civil rights has proposed amending the regulations governing Title IX of the Education Amendments of 1972--which prohibits sex discrimination in programs that receive federal money--to allow more flexibility in offering single-sex schools or classes. This article discusses the rapid growth of…

  5. EC nuclear: toward the single market 1993

    International Nuclear Information System (INIS)

    Brill, L.V.

    1991-01-01

    The setting-up of a single market has long been an objective (Euratom Treaty). One of the Commission's (CEC) concerns will be to ensure that safety requirements are met in the worldwide trend in standardization of components. Cost advantages (manufacture, operation and maintenance) and improved safety are gained from standardization, and are important in a slack market

  6. WINKLER'S SINGLE-PARAMETER SUBGRADE MODEL FROM ...

    African Journals Online (AJOL)

    Preferred Customer

    Page 1 ... corresponding single-parameter Winkler model presented in this work. Keywords: Heterogeneous subgrade, Reissner's simplified continuum, Shear interaction, Simplified continuum, Winkler ... model in practical applications and its long time familiarity among practical engineers, its usage has endured to this date ...

  7. APPLICATIONS OF A SINGLE CARBON ELECTRODE

    African Journals Online (AJOL)

    Preferred Customer

    Page 1 ... ABSTRACT: A single carbon electrode used with a common arc welder has been successfully used on steel to weld, to surface harden, to spot weld sheet, to pierce holes and to do simple brazing. ... applications: welding, spot welding, hole piercing, etc. The metal tube holding the carbon electrodes is banded with ...

  8. The Media, Marketing, and Single Sex Schooling

    Science.gov (United States)

    Mills, Martin

    2004-01-01

    The Australian media's interest in education, as in many Anglophone countries, is frequently dominated by concerns about boys in schools. In 2002, in a country region of the Australian State of Queensland, this concern was evident in a debate on the merits of single sex schooling that took place in a small local newspaper. The debate was fuelled…

  9. Single phase induction motor with starting performance

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, M.; Demeter, E. [Research Institute for Electrical Machines, ICPE-ME, Bucharest (Romania); Navrapescu, V. [University `Politehnica` Bucharest, Electrical Engineering Faculty Splaiul Independentei, Bucharest (Romania)

    1997-12-31

    The paper presents problems related to a special type of single phase induction motor. The main novelty consists in the use of a conducting (aluminium casted) shell distributed on the periferic region of the rotor. As a result the starting performance, as well as the rated ones, is much improved in comparison with the conventional construction. (orig.) 4 refs.

  10. Delayed Single Stage Perineal Posterior Urethroplasty

    International Nuclear Information System (INIS)

    Ali, S.; Shahnawaz; Shahzad, I.; Baloch, M. U.

    2015-01-01

    Objective: To determine the delayed single stage perineal posterior urethroplasty for treatment of posterior urethral stricture/distraction defect. Study Design: Descriptive case series. Place and Duration of Study: Department of Urology, Jinnah Postgraduate Medical Centre, Karachi, from January 2009 to December 2011. Methodology: Patients were selected for delayed single stage perineal posterior urethroplasty for treatment of posterior urethral stricture / distraction defect. All were initially suprapubically catheterized followed by definitive surgery after at least 3 months. Results: Thirty male patients were analyzed with a mean follow-up of 10 months, 2 patients were excluded as they developed failure in first 3 months postoperatively. Mean patients age was 26.25 ± 7.9 years. On follow-up, 7 patients (23.3 percentage) experienced recurrent stricture during first 10 months. Five (16.6 percentage) patients were treated successfully with single direct visual internal urethrotomy. Two patients (6.6 percentage) had more than one direct visual internal urethrotomy and considered failed. Re-do perineal urethroplasty was eventually performed. The overall success rate was 93.3 percentage with permissive criteria allowing single direct visual internal urethrotomy and 76.6% with strict criteria allowing no more procedures postoperatively. Conclusion: Posterior anastomotic urethroplasty offers excellent long-term results to patients with posterior urethral trauma and distraction defect even after multiple prior procedures. (author)

  11. Delayed Single Stage Perineal Posterior Urethroplasty.

    Science.gov (United States)

    Ali, Shahzad; Shahnawaz; Shahzad, Iqbal; Baloch, Muhammad Umar

    2015-06-01

    To determine the delayed single stage perineal posterior urethroplasty for treatment of posterior urethral stricture/distraction defect. Descriptive case series. Department of Urology, Jinnah Postgraduate Medical Centre, Karachi, from January 2009 to December 2011. Patients were selected for delayed single stage perineal posterior urethroplasty for treatment of posterior urethral stricture / distraction defect. All were initially suprapubically catheterized followed by definitive surgery after at least 3 months. Thirty male patients were analyzed with a mean follow-up of 10 months, 2 patients were excluded as they developed failure in first 3 months postoperatively. Mean patient's age was 26.25 ± 7.9 years. On follow-up, 7 patients (23.3%) experienced recurrent stricture during first 10 months. Five (16.6%) patients were treated successfully with single direct visual internal urethrotomy. Two patients (6.6%) had more than one direct visual internal urethrotomy and considered failed. Re-do perineal urethroplasty was eventually performed. The overall success rate was 93.3% with permissive criteria allowing single direct visual internal urethrotomy and 76.6% with strict criteria allowing no more procedures postoperatively. Posterior anastomotic urethroplasty offers excellent long-term results to patients with posterior urethral trauma and distraction defect even after multiple prior procedures.

  12. Single Photon Experiments and Quantum Complementarity

    Directory of Open Access Journals (Sweden)

    Georgiev D. D.

    2007-04-01

    Full Text Available Single photon experiments have been used as one of the most striking illustrations of the apparently nonclassical nature of the quantum world. In this review we examine the mathematical basis of the principle of complementarity and explain why the Englert-Greenberger duality relation is not violated in the configurations of Unruh and of Afshar.

  13. Quantum sensors based on single diamond defects

    International Nuclear Information System (INIS)

    Jelezko Fedor

    2014-01-01

    NV centers in diamond are promising sensors able to detect electric and magnetic fields at nanoscale. Here we report on the detection of biomolecules using magnetic noise induced by their electron and nuclear spins. Presented results show first steps towards establishing novel sensing technology for visualizing single proteins and study of their dynamics. (author)

  14. Nano-soldering to single atomic layer

    Science.gov (United States)

    Girit, Caglar O [Berkeley, CA; Zettl, Alexander K [Kensington, CA

    2011-10-11

    A simple technique to solder submicron sized, ohmic contacts to nanostructures has been disclosed. The technique has several advantages over standard electron beam lithography methods, which are complex, costly, and can contaminate samples. To demonstrate the soldering technique graphene, a single atomic layer of carbon, has been contacted, and low- and high-field electronic transport properties have been measured.

  15. Lattice effects in YVO3 single crystal

    NARCIS (Netherlands)

    Marquina, C; Sikora, M; Ibarra, MR; Nugroho, AA; Palstra, TTM

    In this paper we report on the lattice effects in the Mott insulator yttrium orthovanadate (YVO3). Linear thermal expansion and magnetostriction experiments have been performed on a single crystal, in the temperature range from 5 K to room temperature. The YVO3 orders antiferromagnetically at T-N =

  16. Measurement error in a single regressor

    NARCIS (Netherlands)

    Meijer, H.J.; Wansbeek, T.J.

    2000-01-01

    For the setting of multiple regression with measurement error in a single regressor, we present some very simple formulas to assess the result that one may expect when correcting for measurement error. It is shown where the corrected estimated regression coefficients and the error variance may lie,

  17. Antiferromagnetism in chromium alloy single crystals

    DEFF Research Database (Denmark)

    Bjerrum Møller, Hans; Trego, A.L.; Mackintosh, A.R.

    1965-01-01

    The antiferromagnetism of single crystals of dilute alloys of V, Mn and Re in Cr has been studied at 95°K and 300°K by neutron diffraction. The addition of V causes the diffraction peaks to decrease in intensity and move away from (100), while Mn and Re cause them to increase and approach (100) s...

  18. The Single Needle Lockstitch Machine. Module 1.

    Science.gov (United States)

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This module on parts of the machine, one in a series on the single needle lockstitch sewing machine for student self-study, contains eight sections. Each section contains the following parts: an introduction, directions, an objective, learning activities, student information, student self-check, check-out activities, and an instructor's final…

  19. An introduction to single implant abutments.

    LENUS (Irish Health Repository)

    Warreth, Abdulhadi

    2013-01-01

    This article is an introduction to single implant abutments and aims to provide basic information about abutments which are essential for all dental personnel who are involved in dental implantology. Clinical Relevance: This article provides a basic knowledge of implants and implant abutments which are of paramount importance, as replacement of missing teeth with oral implants has become a well-established clinical procedure.

  20. Mechanism of single atom switch on silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Thirstrup, C.

    1998-01-01

    We demonstrate single atom switch on silicon which operates by displacement of a hydrogen atom on the silicon (100) surface at room temperature. We find two principal effects by which the switch is controlled: a pronounced maximum of the switching probability as function of sample bias...

  1. Magnetic moment of single layer graphene rings

    Science.gov (United States)

    Margulis, V. A.; Karpunin, V. V.; Mironova, K. I.

    2018-01-01

    Magnetic moment of single layer graphene rings is investigated. An analytical expression for the magnetic moment as a function of the magnetic field flux through the one-dimensional quantum rings is obtained. This expression has the oscillation character. The oscillation period is equal to one flux quanta.

  2. Single side Emitting Transparent OLED lamp

    NARCIS (Netherlands)

    Lifka, H.; Verschuren, C.A.; Bruls, D.M.; Tanase, C.

    2011-01-01

    Transparent OLEDs offer great potential for novel applications. Preferably, the light should be emitted from one side only. This can bedone to some extent by modifying electrode thicknesses, but at the cost of reduced transparency. Here, we demonstrate a new approach tomake single side emissive

  3. Neutron forward diffraction by single crystal prisms

    Indian Academy of Sciences (India)

    We have derived analytic expressions for the deflection as well as transmitted fraction of monochromatic neutrons forward diffracted by a single crystal prism. In the vicinity of a Bragg reflection, the neutron deflection deviates sharply from that for an amorphous prism, exhibiting three orders of magnitude greater sensitivity to ...

  4. Projection operator treatment of single particle resonances

    International Nuclear Information System (INIS)

    Lev, A.; Beres, W.P.

    1976-01-01

    A projection operator method is used to obtain the energy and width of a single particle resonance. The resonance energy is found without scanning. An example of the first g/sub 9/2/ neutron resonance in 40 Ca is given and compared with the traditional phase shift method. The results of both approaches are quite similar. 4 figures

  5. Inclusive single muon production in D0

    International Nuclear Information System (INIS)

    Maciel, A.K.A.

    1993-12-01

    Preliminary cross section measurements from the D0 experiment at Fermilab for the inclusive production of single muons in proton- antiproton collisions at √s = 1.8 TeV are presented. It is found that the experimental results are consistent with those obtained from a Monte Carlo simulation using N.L.O. calculations from ISAJET

  6. Single gene retrieval from thermally degraded DNA

    Indian Academy of Sciences (India)

    To simulate single gene retrieval from ancient DNA, several related factors have been investigated. By monitoring a 889 bp polymerase chain reaction (PCR) product and genomic DNA degradation, we find that heat and oxygen (especially heat) are both crucial factors influencing DNA degradation. The heat influence ...

  7. Properties of single crystal beta''-aluminas

    International Nuclear Information System (INIS)

    Bates, J.B.; Brown, G.M.; Kaneda, T.; Brundage, W.E.; Wang, J.C.; Engstrom, H.

    1979-01-01

    Large single crystals of sodium beta''-alumina were grown by slow evaporation of Na 2 O at 1690 0 C from a mixture of Na 2 CO 3 , MgO, and Al 2 O 3 . Polarized Raman measurements were made on the Na β'' single crystals and on single crystals of Li, K, Rb, and Ag β'' prepared by ion exchange of Na β''. The low frequency Raman spectra of Na, K, Rb, and Ag β'' contained four or more bands due to vibrations of the mobile cations. These results were analyzed by assuming the spectra to be due to the normal modes of a defect cluster consisting of a cation vacancy surrounded by three cations. From model calculations, the Raman band of Na β'' at 33 cm -1 is assigned to the attempt mode for diffusion of Na + ions. The structure of a Ag β'' single crystal was investigated by neutron diffraction, and 20% of the Ag + ion sites were found to be vacant

  8. Single Versus Multiple Parenting: Implications for Infancy.

    Science.gov (United States)

    Eiduson, Bernice T.; And Others

    This study, part of a naturalistic longitudinal study of infants being reared in a variety of family life styles, attempted to establish the extent to which differing parenting patterns affected early developmental outcomes. Subjects were 200 infants: 50 of single mothers who headed their family units, 50 of mothers in communal living groups, and…

  9. Feedback Cooling of a Single Neutral Atom

    NARCIS (Netherlands)

    Koch, Markus; Sames, Christian; Kubanek, Alexander; Apel, Matthias; Balbach, Maximilian; Ourjoumtsev, Alexei; Pinkse, Pepijn Willemszoon Harry; Rempe, Gerhard

    2010-01-01

    We demonstrate feedback cooling of the motion of a single rubidium atom trapped in a high-finesse optical resonator to a temperature of about 160  μK. Time-dependent transmission and intensity-correlation measurements prove the reduction of the atomic position uncertainty. The feedback increases the

  10. Congenital malformation of inner ear, single cavity

    International Nuclear Information System (INIS)

    Torres Pazmino, Julio Cesar; Marrugo Pardo, Gilberto Eduardo

    2010-01-01

    Congenital malformations of the inner ear are rare conditions, but their detection requires high diagnostic accuracy. In this report we describe the case of a patient with single or common cavity, discuss the corresponding radiological images, describe the treatment of this patient with a cochlear implant, and review the classification and differential diagnosis of the other anomalies of the inner ear.

  11. Preparation of single phase molybdenum boride

    International Nuclear Information System (INIS)

    Camurlu, Hasan Erdem

    2011-01-01

    Highlights: → Formation of Mo and a mixture of molybdenum boride phases take place in preparation of molybdenum borides. → It is intricate to prepare single phase molybdenum borides. → Formation of single phase MoB from MoO 3 + B 2 O 3 + Mg mixtures has not been reported previously. → Single phase MoB was successfully prepared through a combination of mechanochemical synthesis and annealing process. - Abstract: The formation of MoB through volume combustion synthesis (VCS), and through mechanochemical synthesis (MCS) followed by annealing has been investigated. MoO 3 , B 2 O 3 and Mg were used as reactants while MgO and NaCl were introduced as diluents. Products were leached in dilute HCl solution and were subjected to X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) examinations. Mo was the major phase component in the VCS products under all the experimental conditions. Mo 2 B, MoB, MoB 2 and Mo 2 B 5 were found as minor phases. Products of MCS contained a mixture of Mo 2 B, MoB, MoB 2 and Mo. After annealing the MCS product at 1400 deg. C for 3 h, single phase α-MoB was obtained.

  12. Parallel single-cell analysis microfluidic platform

    NARCIS (Netherlands)

    van den Brink, Floris Teunis Gerardus; Gool, Elmar; Frimat, Jean-Philippe; Bomer, Johan G.; van den Berg, Albert; le Gac, Severine

    2011-01-01

    We report a PDMS microfluidic platform for parallel single-cell analysis (PaSCAl) as a powerful tool to decipher the heterogeneity found in cell populations. Cells are trapped individually in dedicated pockets, and thereafter, a number of invasive or non-invasive analysis schemes are performed.

  13. Single incision laparoscopic colorectal resection: Our experience

    Directory of Open Access Journals (Sweden)

    Chinnusamy Palanivelu

    2012-01-01

    Full Text Available Background: A prospective case series of single incision multiport laparoscopic colorectal resections for malignancy using conventional laparoscopic trocars and instruments is described. Materials and Methods: Eleven patients (seven men and four women with colonic or rectal pathology underwent single incision multiport laparoscopic colectomy/rectal resection from July till December 2010. Four trocars were placed in a single transumblical incision. The bowel was mobilized laparoscopically and vessels controlled intracorporeally with either intra or extracorporeal anastomosis. Results: Three patients had carcinoma in the caecum, one in the hepatic flexure, two in the rectosigmoid, one in the descending colon, two in the rectum and two had ulcerative pancolitis (one with high grade dysplasia and another with carcinoma rectum. There was no conversion to standard multiport laparoscopy or open surgery. The median age was 52 years (range 24-78 years. The average operating time was 130 min (range 90-210 min. The average incision length was 3.2 cm (2.5-4.0 cm. There were no postoperative complications. The average length of stay was 4.5 days (range 3-8 days. Histopathology showed adequate proximal and distal resection margins with an average lymph node yield of 25 nodes (range 16-30 nodes. Conclusion: Single incision multiport laparoscopic colorectal surgery for malignancy is feasible without extra cost or specialized ports/instrumentation. It does not compromise the oncological radicality of resection. Short-term results are encouraging. Long-term results are awaited.

  14. Demonstrating quantum random with single photons

    International Nuclear Information System (INIS)

    Bronner, Patrick; Strunz, Andreas; Meyn, Jan-Peter; Silberhorn, Christine

    2009-01-01

    We present an experiment for education which demonstrates random transmission or reflection of heralded single photons on beam splitters. With our set-up, we can realize different quantum random experiments by appropriate settings of polarization rotators. The concept of entanglement is motivated by correlated randomness. The experiments are suitable for undergraduate education and are available as interactive screen experiments.

  15. Single versus multimodality training basic laparoscopic skills

    NARCIS (Netherlands)

    Brinkman, W.M.; Havermans, S.Y.; Buzink, S.N.; Botden, S.M.B.I.; Jakimowicz, J.J.; Schoot, B.C.

    2012-01-01

    Introduction - Even though literature provides compelling evidence of the value of simulators for training of basic laparoscopic skills, the best way to incorporate them into a surgical curriculum is unclear. This study compares the training outcome of single modality training with multimodality

  16. Characteristics of photoconductivity in thallium monosulfide single ...

    Indian Academy of Sciences (India)

    This work elucidates the photoconductivity (PC) of thallium monosulfide single crystals. Results are obtained in the 77-300 K temperature range, 1500-4500 V lx excitation intensity, 6-18 V applied voltage, and in the 640-1500 nm wavelength range. Both the ac-photoconductivity (ac-PC) and the spectral distribution of the ...

  17. Capillary Electrophoretic Technologies for Single Cell Metabolomics

    Science.gov (United States)

    Lapainis, Theodore E.

    2009-01-01

    Understanding the functioning of the brain is hindered by a lack of knowledge of the full complement of neurotransmitters and neuromodulatory compounds. Single cell measurements aid in the discovery of neurotransmitters used by small subsets of neurons that would be diluted below detection limits or masked by ubiquitous compounds when working with…

  18. Single scrotal incision orchidopexy for palpable undescended

    International Nuclear Information System (INIS)

    Ahmad, A.; Safdar, C.A.; Yasir, U.; Rasool, N.; Kanwal, S.; Boota, M.; Rehman, J.U.

    2014-01-01

    To retrospectively asses the results of single scrotal incision orchidopexy (SSIO) performed at our centre with ligation of the patent processus vaginalis in children having palpable undescended testes (UDT). Study Design: Quasi-experimental with retrospective data. Place and Duration of Study: Department of Paediatric surgery Military Hospital Rawalpindi, from April 2007 to December 2011. Patients and Methods: After making a single transverse incision at superior scrotal border, the testis was identified; gubernaculums and the sac were dissected to the highest level and divided. The testis was placed into the scrotum and fixed to the scrotal fascia/skin. All patients were assessed at 2 weeks, 2 months and 6 months post operatively, and then yearly. Results: A total of 38 orchidopexies were performed in 33 patients. The patients age ranged from 14 months to 7 years (mean:2.1 years). Bilateral UDT were found in 5 patients (15.1%). Operative time ranged from 20 to 45 minutes (mean: 36 minutes). The single scrotal incision technique was successful in all 38 cases (100%). All testes were easily fixed in the scrotum. Two patients (5.2%) developed scrotal haematoma and one patient (2.6%) developed stitch abscess. All showed good an atomical and cosmetic results up to a minimum of six months of follow-up. Conclusion: Single scrotal incision orchidopexy for palpable undescended testis is a simple and safe technique. It has shown to consume shorter time and give good cosmetic results. (author)

  19. Spectrally resolved single-molecule electrometry

    Science.gov (United States)

    Ruggeri, F.; Krishnan, M.

    2018-03-01

    Escape-time electrometry is a recently developed experimental technique that offers the ability to measure the effective electrical charge of a single biomolecule in solution with sub-elementary charge precision. The approach relies on measuring the average escape-time of a single charged macromolecule or molecular species transiently confined in an electrostatic fluidic trap. Comparing the experiments with the predictions of a mean-field model of molecular electrostatics, we have found that the measured effective charge even reports on molecular conformation, e.g., folded or disordered state, and non-uniform charge distribution in disordered proteins or polyelectrolytes. Here we demonstrate the ability to use the spectral dimension to distinguish minute differences in electrical charge between individual molecules or molecular species in a single simultaneous measurement, under identical experimental conditions. Using one spectral channel for referenced measurement, this kind of photophysical distinguishability essentially eliminates the need for accurate knowledge of key experimental parameters, otherwise obtained through intensive characterization of the experimental setup. As examples, we demonstrate the ability to detect small differences (˜5%) in the length of double-stranded DNA fragments as well as single amino acid exchange in an intrinsically disordered protein, prothymosin α.

  20. Tuneable graphene nanopores for single biomolecule detection.

    Science.gov (United States)

    Al-Dirini, Feras; Mohammed, Mahmood A; Hossain, Md Sharafat; Hossain, Faruque M; Nirmalathas, Ampalavanapillai; Skafidas, Efstratios

    2016-05-21

    Solid-state nanopores are promising candidates for next generation DNA and protein sequencing. However, once fabricated, such devices lack tuneability, which greatly restricts their biosensing capabilities. Here we propose a new class of solid-state graphene-based nanopore devices that exhibit a unique capability of self-tuneability, which is used to control their conductance, tuning it to levels comparable to the changes caused by the translocation of a single biomolecule, and hence, enabling high detection sensitivities. Our presented quantum simulation results suggest that the smallest amino acid, glycine, when present in water and in an aqueous saline solution can be detected with high sensitivity, up to a 90% change in conductance. Our results also suggest that passivating the device with nitrogen, making it an n-type device, greatly enhances its sensitivity, and makes it highly sensitive to not only the translocation of a single biomolecule, but more interestingly to intramolecular electrostatics within the biomolecule. Sensitive detection of the carboxyl group within the glycine molecule, which carries a charge equivalent to a single electron, is achieved with a conductance change that reaches as high as 99% when present in an aqueous saline solution. The presented findings suggest that tuneable graphene nanopores, with their capability of probing intramolecular electrostatics, could pave the way towards a new generation of single biomolecule detection devices.

  1. Mixed biexcitons in single quantum wells

    DEFF Research Database (Denmark)

    Wagner, Hans Peter; Langbein, Wolfgang Werner; Hvam, Jørn Märcher

    1999-01-01

    Biexcitonic complexes in a ZnSe single quantum well are investigated by spectrally resolved four-wave mixing (FWM). The formation of heavy-heavy-hole XXh and of mixed heavy-light-hole XXm biexcitons showing binding energies of Delta(h) = 4.8 meV and Delta(m)= 2.8 meV is identified by polarization...

  2. The effect of a single recombination event

    DEFF Research Database (Denmark)

    Schierup, Mikkel Heide; Jensen, Thomas Mailund; Wiuf, Carsten

    We investigate the variance in how visible a single recombination event is in a SNP data set as a function of the type of recombination event and its age. Data is simulated under the coalescent with recombination and inference is by the popular composite likelihood methods. The major determinant...

  3. High-Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal

    2010-01-01

    We demonstrate single nanowire tunnel diodes with room temperature peak current densities of up to 329 A/cm(2). Despite the large surface to volume ratio of the type-II InP-GaAs axial heterostructure nanowires, we measure peak to valley current ratios (PVCR) of up to 8.2 at room temperature and 27...

  4. Single event phenomena in atmospheric neutron environments

    International Nuclear Information System (INIS)

    Gossett, C.A.; Hughlock, B.W.; Katoozi, M.; LaRue, G.S.; Wender, S.A.

    1993-01-01

    As integrated circuit technology achieves higher density through smaller feature sizes and as the airplane manufacturing industry integrates more sophisticated electronic components into the design of new aircraft, it has become increasingly important to evaluate the contribution of single event effects, primarily Single Event Upset (SEU), to the safety and reliability of commercial aircraft. In contrast to the effects of radiation on electronic systems in space applications for which protons and heavy ions are of major concern, in commercial aircraft applications the interactions of high energy neutrons are the dominant cause of single event effects. These high energy neutrons are produced by the interaction of solar and galactic cosmic rays, principally protons and heavy ions, in the upper atmosphere. This paper will describe direct experimental measurements of neutron-induced Single Event Effect (SEE) rates in commercial high density static random access memories in a neutron environment characteristic of that at commercial airplane altitudes. The first experimental measurements testing current models for neutron-silicon burst generation rates will be presented, as well as measurements of charge collection in silicon test structures as a function of neutron energy. These are the first laboratory SEE and charge collection measurements using a particle beam having a continuum energy spectrum and with a shape nearly identical to that observed during flight

  5. Single-mode biological distributed feedback laser

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Maier-Flaig, Florian; Lemmer, Uli

    2013-01-01

    Single-mode second order distributed feedback (DFB) lasers of riboflavin (vitamin B2) doped gelatine films on nanostructured low refractive index material are demonstrated. Manufacturing is based on a simple UV nanoimprint and spin-coating. Emission wavelengths of 543 nm and 562 nm for two...

  6. Noninvasive prenatal diagnosis for single gene disorders.

    Science.gov (United States)

    Allen, Stephanie; Young, Elizabeth; Bowns, Benjamin

    2017-04-01

    Noninvasive prenatal diagnosis for single gene disorders is coming to fruition in its clinical utility. The presence of cell-free DNA in maternal plasma has been recognized for many years, and a number of applications have developed from this. Noninvasive prenatal diagnosis for single gene disorders has lagged behind due to complexities of technology development, lack of investment and the need for validation samples for rare disorders. Publications are emerging demonstrating a variety of technical approaches and feasibility of clinical application. Techniques for analysis of cell-free DNA including digital PCR, next-generation sequencing and relative haplotype dosage have been used most often for assay development. Analysis of circulating fetal cells in the maternal blood is still being investigated as a viable alternative and more recently transcervical trophoblast cells. Studies exploring ethical and social issues are generally positive but raise concerns around the routinization of prenatal testing. Further work is necessary to make testing available to all patients with a pregnancy at risk of a single gene disorder, and it remains to be seen if the development of more powerful technologies such as isolation and analysis of single cells will shift the emphasis of noninvasive prenatal diagnosis. As testing becomes possible for a wider range of conditions, more ethical questions will become relevant.

  7. Biological Information Processing in Single Microtubules

    Science.gov (United States)

    2014-03-05

    generated by synchronized oscillations of microtubules, centrosomes and chromosomes regulate the dynamics of mitosis and meiosis, Yue Zhao and Qimin...of frequency by a single microtubule. Green arrows depict the peaks that appear in absorption and disappear in transmission. Purple arrows show

  8. Single-Sex Schools and the Law.

    Science.gov (United States)

    Brown, Frank; Russo, Charles J.

    1999-01-01

    Reviews single-sex schools' history and legal status. Explores constitutional dimensions of gender-based discrimination delineated in five leading cases (in Philadelphia, New York City, Detroit, Mississippi, and Virginia). Due to claims of Equal Protection Clause and/or Title IX violations, such schools are unlikely to proliferate. (20 references)…

  9. New frontiers in single-cell analysis

    OpenAIRE

    Templer, Richard H.; Ces, Oscar

    2008-01-01

    For this special issue of J. R. Soc. Interface we present an overview of the driving forces behind technological advances in the field of single-cell analysis. These range from increasing our understanding of cellular heterogeneity through to the study of rare cells, areas of research that cannot be tackled effectively using current high-throughput population-based averaging techniques.

  10. Interactive Screen Experiments with Single Photons

    Science.gov (United States)

    Bronner, Patrick; Strunz, Andreas; Silberhorn, Christine; Meyn, Jan-Peter

    2009-01-01

    Single photons are used for fundamental quantum physics experiments as well as for applications. Originally being a topic of advance courses, such experiments are increasingly a subject of undergraduate courses. We provide interactive screen experiments (ISE) for supporting the work in a real laboratory, and for students who do not have access to…

  11. Method for manufacturing a single crystal nanowire

    NARCIS (Netherlands)

    van den Berg, Albert; Bomer, Johan G.; Carlen, Edwin; Chen, S.; Kraaijenhagen, Roderik Adriaan; Pinedo, Herbert Michael

    2013-01-01

    A method for manufacturing a single crystal nano-structure is provided comprising the steps of providing a device layer with a 100 structure on a substrate; providing a stress layer onto the device layer; patterning the stress layer along the 110 direction of the device layer; selectively removing

  12. Method for manufacturing a single crystal nanowire

    NARCIS (Netherlands)

    van den Berg, Albert; Bomer, Johan G.; Carlen, Edwin; Chen, S.; Kraaijenhagen, R.A.; Pinedo, Herbert Michael

    2010-01-01

    A method for manufacturing a single crystal nano-structure is provided comprising the steps of providing a device layer with a 100 structure on a substrate; providing a stress layer onto the device layer; patterning the stress layer along the 110 direction of the device layer; selectively removing

  13. Overview of ESO Large Single Dish Study

    Science.gov (United States)

    Testi, Leonardo

    2018-01-01

    In this talk I will briefly summarize the motivation, methodology and outcome of the ESO Submm Single Dish Strategy WG. The WG was established by the ESO Director for Science and completed its work at the end of 2015. I will summarize the status of the report recommendations, which, among other things, led to the organization of the AtLAST workshop.

  14. Top quark property measurements in single top

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00386283; The ATLAS collaboration

    2016-01-01

    A review of the recent results on measurements of top quark properties in single top quark processes, performed at the LHC by ATLAS and CMS is presented. The measurements are in good agreement with predictions and no deviations from Standard Model expectations have been observed.

  15. Relationship between internal dosimetry and DNA double strand breaks in lymphocytes after radionuclide therapy; Zusammenhang zwischen physikalischer Dosimetrie und DNA Doppelstrangbruechen in Lymphozyten nach Radionuklidtherapie

    Energy Technology Data Exchange (ETDEWEB)

    Eberlein, Uta

    2015-09-30

    In radionuclide therapy radiopharmaceuticals are administered mostly systemically. Primarily, beta-emitters are used because of their short range in tissue. As a result the radiopharmaceutical distributes within the human body and accumulates in organs and target structures. Thus, the body is irradiated internally, in contrast to external irradiation in radiotherapy. The pattern of the activity distribution within the human body is determined by the physical and chemical properties of the radiopharmaceutical. Furthermore, the amount of activity and its accumulation in organs or tissues is essential for the calculation of the absorbed dose which defines the energy deposited in the body by ionizing radiation. During internal or external irradiation, patients are exposed to ionizing radiation which does not only destroy the malignant cells but also damages healthy tissue and cells. This is mainly caused by direct and indirect interaction of the radiation with the DNA which damages the DNA structure. Most frequently, there are single strand breaks and base damages. DNA double strand breaks (DSBs) are rare; nevertheless, they are the most critical lesions for cells as repairing the damage is difficult. Unrepaired or misrepaired DNA could cause mutations, chromosomal aberrations or lead to cell death. The formation of a DNA DSB in nuclear chromatin results in the rapid phosphorylation of the histone H2 variant H2AX, then called gamma-H2AX. Furthermore, DSBs also recruit the damage sensor 53BP1 to the chromatin surrounding the DSBs, which leads to 53BP1 and gamma-H2AX co-localization in the chromatin surrounding a DSB. By immunofluorescence staining with gamma-H2AX and 53BP1 antibodies those biomarkers can be addressed by microscopically visible DNA damage protein foci, this is also known as the DNA damage focus assay. With progression of DSB repair, gamma-H2AX and 53BP1 foci disappear. It is assumed that one focus corresponds to one DSB. Therefore, the number of foci per

  16. Single Molecule Analysis Research Tool (SMART: an integrated approach for analyzing single molecule data.

    Directory of Open Access Journals (Sweden)

    Max Greenfeld

    Full Text Available Single molecule studies have expanded rapidly over the past decade and have the ability to provide an unprecedented level of understanding of biological systems. A common challenge upon introduction of novel, data-rich approaches is the management, processing, and analysis of the complex data sets that are generated. We provide a standardized approach for analyzing these data in the freely available software package SMART: Single Molecule Analysis Research Tool. SMART provides a format for organizing and easily accessing single molecule data, a general hidden Markov modeling algorithm for fitting an array of possible models specified by the user, a standardized data structure and graphical user interfaces to streamline the analysis and visualization of data. This approach guides experimental design, facilitating acquisition of the maximal information from single molecule experiments. SMART also provides a standardized format to allow dissemination of single molecule data and transparency in the analysis of reported data.

  17. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Lu, H. Peter [Bowling Green State Univ., Bowling Green, OH (United States). Dept. of Chemistry and Center for Photochemical Sciences

    2017-11-28

    This project is focused on the use of single-molecule high spatial and temporal resolved techniques to study molecular dynamics in condensed phase and at interfaces, especially, the complex reaction dynamics associated with electron and energy transfer rate processes. The complexity and inhomogeneity of the interfacial ET dynamics often present a major challenge for a molecular level comprehension of the intrinsically complex systems, which calls for both higher spatial and temporal resolutions at ultimate single-molecule and single-particle sensitivities. Combined single-molecule spectroscopy and electrochemical atomic force microscopy approaches are unique for heterogeneous and complex interfacial electron transfer systems because the static and dynamic inhomogeneities can be identified and characterized by studying one molecule at a specific nanoscale surface site at a time. The goal of our project is to integrate and apply these spectroscopic imaging and topographic scanning techniques to measure the energy flow and electron flow between molecules and substrate surfaces as a function of surface site geometry and molecular structure. We have been primarily focusing on studying interfacial electron transfer under ambient condition and electrolyte solution involving both single crystal and colloidal TiO2 and related substrates. The resulting molecular level understanding of the fundamental interfacial electron transfer processes will be important for developing efficient light harvesting systems and broadly applicable to problems in fundamental chemistry and physics. We have made significant advancement on deciphering the underlying mechanism of the complex and inhomogeneous interfacial electron transfer dynamics in dyesensitized TiO2 nanoparticle systems that strongly involves with and regulated by molecule-surface interactions. We have studied interfacial electron transfer on TiO2 nanoparticle surfaces by using ultrafast single

  18. Kinematics of electroweak single top quark production

    International Nuclear Information System (INIS)

    Lueck, Jan; Karlsruhe U., EKP

    2006-01-01

    In this thesis, the t-channel matching procedure of two single-top signal Monte Carlo samples is optimized. The s- and matched t-channel samples, generated by MadEvent, are validated by comparing to ZTOP next-to-leading-order calculations. We find good agreement for all kinematic distributions we investigate, except for softer light quark jets due to gluon radiation. Since this has only minor impact on the s-channel, the corresponding MadEvent sample performs its task as expected. For the t-channel, we can conclude that the applied matching procedure leads to a MadEvent sample that successfully describes the kinematic distributions and rates of the 2nd-b quark. However, small differences remain. The discrepancy in the p T -ordered 2nd-leading light jets is mainly due to the absence of initial state gluon splitting and initial and final state gluon radiation matrix elements in the MadEvent sample production. The subsequent PYTHIA showering of the partons is apparently inappropriate for modeling those contributions and not intended for this purpose. The proper way would be to produce all relevant NLO matrix elements and match them as proposed in reference [15]. At present, an NLO-MC-generator for single-top is in preparation [41]. Probably it will be available for future iterations of single-top analyses and will redundantize further matching procedures. We estimate the systematic uncertainty on the single-top acceptance due to the Monte Carlo modeling and find an uncertainty of about 1% on the t-channel acceptance. We obtain a negligible uncertainty well below 1% on the s-channel acceptance. These acceptance uncertainties are very well acceptable for the single-top analyses that are currently under way. A sensitivity study of the simultaneous cross section measurement of the s- and t-channel single-top production modes is conducted. For this purpose, only statistical uncertainties are included. For a future integrated luminosity of 1 fb -1 , we expect to obtain an s

  19. Single ion implantation for single donor devices using Geiger mode detectors

    International Nuclear Information System (INIS)

    Bielejec, E; Seamons, J A; Carroll, M S

    2010-01-01

    Electronic devices that are designed to use the properties of single atoms such as donors or defects have become a reality with recent demonstrations of donor spectroscopy, single photon emission sources, and magnetic imaging using defect centers in diamond. Ion implantation, an industry standard for atom placement in materials, requires augmentation for single ion capability including a method for detecting a single ion arrival. Integrating single ion detection techniques with the single donor device construction region allows single ion arrival to be assured. Improving detector sensitivity is linked to improving control over the straggle of the ion as well as providing more flexibility in lay-out integration with the active region of the single donor device construction zone by allowing ion sensing at potentially greater distances. Using a remotely located passively gated single ion Geiger mode avalanche diode (SIGMA) detector we have demonstrated 100% detection efficiency at a distance of >75 μm from the center of the collecting junction. This detection efficiency is achieved with sensitivity to ∼600 or fewer electron-hole pairs produced by the implanted ion. Ion detectors with this sensitivity and integrated with a thin dielectric, for example a 5 nm gate oxide, using low energy Sb implantation would have an end of range straggle of -1 and 10 -4 for operation temperatures of ∼300 K and ∼77 K, respectively. Low temperature operation and reduced false, 'dark', counts are critical to achieving high confidence in single ion arrival. For the device performance in this work, the confidence is calculated as a probability of >98% for counting one and only one ion for a false count probability of 10 -4 at an average ion number per gated window of 0.015.

  20. Inkjet printing of single-crystal films.

    Science.gov (United States)

    Minemawari, Hiromi; Yamada, Toshikazu; Matsui, Hiroyuki; Tsutsumi, Jun'ya; Haas, Simon; Chiba, Ryosuke; Kumai, Reiji; Hasegawa, Tatsuo

    2011-07-13

    The use of single crystals has been fundamental to the development of semiconductor microelectronics and solid-state science. Whether based on inorganic or organic materials, the devices that show the highest performance rely on single-crystal interfaces, with their nearly perfect translational symmetry and exceptionally high chemical purity. Attention has recently been focused on developing simple ways of producing electronic devices by means of printing technologies. 'Printed electronics' is being explored for the manufacture of large-area and flexible electronic devices by the patterned application of functional inks containing soluble or dispersed semiconducting materials. However, because of the strong self-organizing tendency of the deposited materials, the production of semiconducting thin films of high crystallinity (indispensable for realizing high carrier mobility) may be incompatible with conventional printing processes. Here we develop a method that combines the technique of antisolvent crystallization with inkjet printing to produce organic semiconducting thin films of high crystallinity. Specifically, we show that mixing fine droplets of an antisolvent and a solution of an active semiconducting component within a confined area on an amorphous substrate can trigger the controlled formation of exceptionally uniform single-crystal or polycrystalline thin films that grow at the liquid-air interfaces. Using this approach, we have printed single crystals of the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C(8)-BTBT) (ref. 15), yielding thin-film transistors with average carrier mobilities as high as 16.4 cm(2) V(-1) s(-1). This printing technique constitutes a major step towards the use of high-performance single-crystal semiconductor devices for large-area and flexible electronics applications.

  1. Picosecond, single pulse electron linear accelerator

    International Nuclear Information System (INIS)

    Kikuchi, Riichi; Kawanishi, Masaharu

    1979-01-01

    The picosecond, single pulse electron linear accelerators, are described, which were installed in the Nuclear Engineering Laboratory of the University of Tokyo and in the Nuclear Radiation Laboratory of the Osaka University. The purpose of the picosecond, single pulse electron linear accelerators is to investigate the very short time reaction of the substances, into which gamma ray or electron beam enters. When the electrons in substances receive radiation energy, the electrons get high kinetic energy, and the energy and the electric charge shift, at last to the quasi-stable state. This transient state can be experimented with these special accelerators very accurately, during picoseconds, raising the accuracy of the time of incidence of radiation and also raising the accuracy of observation time. The outline of these picosecond, single pulse electron linear accelerators of the University of Tokyo and the Osaka University, including the history, the systems and components and the output beam characteristics, are explained. For example, the maximum energy 30 -- 35 MeV, the peak current 1 -- 8 n C, the pulse width 18 -- 40 ps, the pulse repetition rate 200 -- 720 pps, the energy spectrum 1 -- 1.8% and the output beam diameter 2 -- 5 mm are shown as the output beam characteristics of the accelerators in both universities. The investigations utilizing the picosecond single pulse electron linear accelerators, such as the investigation of short life excitation state by pulsed radiation, the dosimetry study of pulsed radiation, and the investigation of the transforming mechanism and the development of the transforming technology from picosecond, single pulse electron beam to X ray, vacuum ultraviolet ray and visual ray, are described. (Nakai, Y.)

  2. What happens if you single out? An experiment

    OpenAIRE

    Galeotti, Fabio; Zizzo, Daniel John

    2014-01-01

    We present an experiment investigating the effects of singling out an individual on trust and trustworthiness. We find that (a) trustworthiness falls if there is a singled out subject; (b) non-singled out subjects discriminate against the singled out subject when they are not responsible of the distinct status of this person; (c) under a negative frame, the singled out subject returns significantly less; (d) under a positive frame, the singled out subject behaves bimodally, either selecting v...

  3. Increased sister chromatid cohesion and DNA damage response factor localization at an enzyme-induced DNA double-strand break in vertebrate cells.

    LENUS (Irish Health Repository)

    Dodson, Helen

    2009-10-01

    The response to DNA damage in vertebrate cells involves successive recruitment of DNA signalling and repair factors. We used light microscopy to monitor the genetic dependencies of such localization to a single, induced DNA double strand break (DSB) in vertebrate cells. We used an inducible version of the rare-cutting I-SceI endonuclease to cut a chromosomally integrated I-SceI site beside a Tet operator array that was visualized by binding a Tet repressor-GFP fusion. Formation of gamma-H2AX foci at a single DSB was independent of ATM or Ku70. ATM-deficient cells showed normal kinetics of 53Bp1 recruitment to DSBs, but Rad51 localization was retarded. 53Bp1 and Rad51 foci formation at a single DSB was greatly reduced in H2AX-null DT40 cells. We also observed decreased inter-sister chromatid distances after DSB induction, suggesting that cohesin loading at DSBs causes elevated sister chromatid cohesion. Loss of ATM reduced DSB-induced cohesion, consistent with cohesin being an ATM target in the DSB response. These data show that the same genetic pathways control how cells respond to single DSBs and to multiple lesions induced by whole-cell DNA damage.

  4. All paired up with no place to go: pairing, synapsis, and DSB formation in a balancer heterozygote.

    Directory of Open Access Journals (Sweden)

    Wei J Gong

    2005-11-01

    Full Text Available The multiply inverted X chromosome balancer FM7 strongly suppresses, or eliminates, the occurrence of crossing over when heterozygous with a normal sequence homolog. We have utilized the LacI-GFP: lacO system to visualize the effects of FM7 on meiotic pairing, synapsis, and double-strand break formation in Drosophila oocytes. Surprisingly, the analysis of meiotic pairing and synapsis for three lacO reporter couplets in FM7/X heterozygotes revealed they are paired and synapsed during zygotene/pachytene in 70%-80% of oocytes. Moreover, the regions defined by these lacO couplets undergo double-strand break formation at normal frequency. Thus, even complex aberration heterozygotes usually allow high frequencies of meiotic pairing, synapsis, and double-strand break formation in Drosophila oocytes. However, the frequencies of failed pairing and synapsis were still 1.5- to 2-fold higher than were observed for corresponding regions in oocytes with two normal sequence X chromosomes, and this effect was greatest near a breakpoint. We propose that heterozygosity for breakpoints creates a local alteration in synaptonemal complex structure that is propagated across long regions of the bivalent in a fashion analogous to chiasma interference, which also acts to suppress crossing over.

  5. Nonlinear Dynamics of Photonics for Optical Signal Processing - Optical Frequency Conversion and Optical DSB-to-SSB Conversion

    Science.gov (United States)

    2015-09-17

    photonic system. ML: master laser; SL: slave laser; L; lens; PBS: polarizing beam splitter ; M: mirror; HW: half-wave plate; FR: Faraday rotator; V...microwave generation and stabilization, and photonic microwave amplification. 15. SUBJECT TERMS Non -linear Dynamics, Add-drop

  6. Single Molecule Nanoelectrochemistry in Electrical Junctions.

    Science.gov (United States)

    Nichols, Richard J; Higgins, Simon J

    2016-11-15

    It is now possible to reliably measure single molecule conductance in a wide variety of environments including organic liquids, ultrahigh vacuum, water, ionic liquids, and electrolytes. The most commonly used methods deploy scanning probe microscopes, mechanically formed break junctions, or lithographically formed nanogap contacts. Molecules are generally captured between a pair of facing electrodes, and the junction current response is measured as a function of bias voltage. Gating electrodes can also be added so that the electrostatic potential at the molecular bridge can be independently controlled by this third noncontacting electrode. This can also be achieved in an electrolytic environment using a four-electrode bipotentiostatic configuration, which allows independent electrode potential control of the two contacting electrodes. This is commonly realized using an electrochemical STM and enables single molecule electrical characterization as a function of electrode potential and redox state of the molecular bridge. This has emerged as a powerful tool in modern interfacial electrochemistry and nanoelectrochemistry for studying charge transport across single molecules as a function of electrode potential and the electrolytic environments. Such measurements are possible in electrolytes ranging from aqueous buffers to nonaqueous ionic liquids. In this Account, we illustrate a number of examples of single molecule electrical measurements under electrode potential control use a scanning tunneling microscope (STM) and demonstrate how these can help in the understanding of charge transport in single molecule junctions. Examples showing charge transport following phase coherent tunneling to incoherent charge hopping across redox active molecular bridges are shown. In the case of bipyridinium (or viologen) molecular wires, it is shown how electrochemical reduction leads to an increase of the single molecule conductance, which is controlled by the liquid electrochemical

  7. Single Nucleotide Polymorphism Detection Using Au-Decorated Single-Walled Carbon Nanotube Field Effect Transistors

    Directory of Open Access Journals (Sweden)

    Keum-Ju Lee

    2011-01-01

    Full Text Available We demonstrate that Au-cluster-decorated single-walled carbon nanotubes (SWNTs may be used to discriminate single nucleotide polymorphism (SNP. Nanoscale Au clusters were formed on the side walls of carbon nanotubes in a transistor geometry using electrochemical deposition. The effect of Au cluster decoration appeared as hole doping when electrical transport characteristics were examined. Thiolated single-stranded probe peptide nucleic acid (PNA was successfully immobilized on Au clusters decorating single-walled carbon nanotube field-effect transistors (SWNT-FETs, resulting in a conductance decrease that could be explained by a decrease in Au work function upon adsorption of thiolated PNA. Although a target single-stranded DNA (ssDNA with a single mismatch did not cause any change in electrical conductance, a clear decrease in conductance was observed with matched ssDNA, thereby showing the possibility of SNP (single nucleotide polymorphism detection using Au-cluster-decorated SWNT-FETs. However, a power to discriminate SNP target is lost in high ionic environment. We can conclude that observed SNP discrimination in low ionic environment is due to the hampered binding of SNP target on nanoscale surfaces in low ionic conditions.

  8. Discovery of single top quark production

    Energy Technology Data Exchange (ETDEWEB)

    Gillberg, Dag [Simon Fraser Univ., Burnaby, BC (Canada)

    2009-04-01

    The top quark is by far the heaviest known fundamental particle with a mass nearing that of a gold atom. Because of this strikingly high mass, the top quark has several unique properties and might play an important role in electroweak symmetry breaking - the mechanism that gives all elementary particles mass. Creating top quarks requires access to very high energy collisions, and at present only the Tevatron collider at Fermilab is capable of reaching these energies. Until now, top quarks have only been observed produced in pairs via the strong interaction. At hadron colliders, it should also be possible to produce single top quarks via the electroweak interaction. Studies of single top quark production provide opportunities to measure the top quark spin, how top quarks mix with other quarks, and to look for new physics beyond the standard model. Because of these interesting properties, scientists have been looking for single top quarks for more than 15 years. This thesis presents the first discovery of single top quark production. An analysis is performed using 2.3 fb-1 of data recorded by the D0 detector at the Fermilab Tevatron Collider at centre-of-mass energy √s = 1.96 TeV. Boosted decision trees are used to isolate the single top signal from background, and the single top cross section is measured to be σ(p$\\bar{p}$ → tb + X, tqb + X) = 3.74-0.74+0.95 pb. Using the same analysis, a measurement of the amplitude of the CKM matrix element Vtb, governing how top and b quarks mix, is also performed. The measurement yields: |V{sub tb}|f1L| = 1.05 -0.12+0.13, where f1L is the left-handed Wtb coupling. The separation of signal from background is improved by combining the boosted decision trees with two other multivariate techniques. A new cross section measurement is performed, and the significance for the excess over the predicted background exceeds 5

  9. Going single but not solo with podocytes: potentials, limitations, and pitfalls of single-cell analysis.

    Science.gov (United States)

    Schiffer, Mario

    2017-11-01

    Single-cell RNA-sequence (RNA-seq) is a widely used tool to study biological questions in single cells. The discussed study identified 92 genes being predominantly expressed in podocytes based on a 5-fold higher expression compared with endothelial and mesangial cells. In addition to technical pitfalls, the question that is discussed in this commentary is whether results of a single-cell RNAseq study are able to deliver expression data that truly characterize a podocyte. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  10. The power of a single trajectory

    Science.gov (United States)

    Schnellbächer, Nikolas D.; Schwarz, Ulrich S.

    2018-03-01

    Random walks are often evaluated in terms of their mean squared displacements, either for a large number of trajectories or for one very long trajectory. An alternative evaluation is based on the power spectral density, but here it is less clear which information can be extracted from a single trajectory. For continuous-time Brownian motion, Krapf et al now have mathematically proven that the one property that can be reliably extracted from a single trajectory is the frequency dependence of the ensemble-averaged power spectral density (Krapf et al 2018 New J. Phys. 20 023029). Their mathematical analysis also identifies the appropriate frequency window for this procedure and shows that the diffusion coefficient can be extracted by averaging over a small number of trajectories. The authors have verified their analytical results both by computer simulations and experiments.

  11. Single-electron tunnel junction array

    International Nuclear Information System (INIS)

    Likharev, K.K.; Bakhvalov, N.S.; Kazacha, G.S.; Serdyukova, S.I.

    1989-01-01

    The authors have carried out an analysis of statics and dynamics of uniform one-dimensional arrays of ultrasmall tunnel junctions. The correlated single-electron tunneling in the junctions of the array results in its behavior qualitatively similar to that of the Josephson transmission line. In particular, external electric fields applied to the array edges can inject single-electron-charged solitons into the array interior. Shape of such soliton and character of its interactions with other solitons and the array edges are very similar to those of the Josephson vortices (sine-Gordon solitons) in the Josephson transmission line. Under certain conditions, a coherent motion of the soliton train along the array is possible, resulting in generation of narrowband SET oscillations with frequency f/sub s/ = /e where is the dc current flowing along the array

  12. Single Coronary Artery with Aortic Regurgitation

    International Nuclear Information System (INIS)

    Katsetos, Manny C.; Toce, Dale T.

    2003-01-01

    An isolated single coronary artery can be associated with normal life expectancy; however, patients are at an increased risk of sudden death. A case is reported of a 54-year-old man with several months of chest pressure with activity. On exercise Sestamibi stress testing, the patient developed a hypotensive response with no symptoms and minimal electrocardiographic changes. Nuclear scanning demonstrated reversible septal and lateral perfusion defects consistent with severe ischemia. Coronary angiography revealed a single coronary artery with the right coronary artery arising from the left main. There were high-grade stenotic lesions in the left anterior descending and circumflex arteries with only moderate atherosclerotic disease in the right coronary artery. An aortogram showed 2-3+ aortic regurgitation, with an ejection fraction of 45% on ventriculography. The patient underwent four-vessel revascularization and aortic valve replacement and did well postoperatively

  13. Missing data imputation: focusing on single imputation.

    Science.gov (United States)

    Zhang, Zhongheng

    2016-01-01

    Complete case analysis is widely used for handling missing data, and it is the default method in many statistical packages. However, this method may introduce bias and some useful information will be omitted from analysis. Therefore, many imputation methods are developed to make gap end. The present article focuses on single imputation. Imputations with mean, median and mode are simple but, like complete case analysis, can introduce bias on mean and deviation. Furthermore, they ignore relationship with other variables. Regression imputation can preserve relationship between missing values and other variables. There are many sophisticated methods exist to handle missing values in longitudinal data. This article focuses primarily on how to implement R code to perform single imputation, while avoiding complex mathematical calculations.

  14. Ant parasite queens revert to mating singly

    DEFF Research Database (Denmark)

    Sumner, Seirian; Hughes, William Owen Hamar; Pedersen, Jes Søe

    2004-01-01

    quantified and they tend to be similar in related species. Here we compare the mating strategies of the leaf-cutting ant Acromyrmex echinatior and its recently derived social parasite Acromyrmex insinuator, which is also its closest relative 2 (see Fig. 1 ). We find that although the host queens mate with up......A parasitic ant has abandoned the multiple mating habit of the queens of its related host. Multiple mating (polyandry) is widespread among animal groups, particularly insects 1 . But the factors that maintain it and underlie its evolution are hard to verify because benefits and costs are not easily...... to a dozen different males, the social parasite mates only singly. This rapid and surprising reversion to single mating in a socially parasitic ant indicates that the costs of polyandry are probably specific to a free-living lifestyle....

  15. Not Only Single Mating in Stingless Bees

    Science.gov (United States)

    Paxton, Robert J.; Weißschuh, Nicole; Engels, Wolf; Hartfelder, Klaus; Quezada-Euan, J. Javier G.

    Queens of the large, pantropical and fully eusocial taxon Meliponinae (stingless bees) are generally considered to be singly mated. We indirectly estimated queen mating frequency in two meliponids, Melipona beecheii and Scaptotrigona postica, by examining genotypes of workers at microsatellite DNA loci. Microsatellites were highly variable, providing suitable markers with which to assign patrilinial origin of workers within colonies headed by single queens. Queen mating frequency varied between 1 and 3 (M. beecheii) and 1 and 6 (S. postica), representing the first clear documentation of polyandry in the Meliponinae. Effective paternity frequency, me, was lower, although above 2 for S. postica. Stingless bees may provide suitable subjects for the testing of recent inclusive fitness arguments describing intracolony kin conflict in social Hymenoptera.

  16. Single-Crystal Diamond Nanobeam Waveguide Optomechanics

    Science.gov (United States)

    Khanaliloo, Behzad; Jayakumar, Harishankar; Hryciw, Aaron C.; Lake, David P.; Kaviani, Hamidreza; Barclay, Paul E.

    2015-10-01

    Single-crystal diamond optomechanical devices have the potential to enable fundamental studies and technologies coupling mechanical vibrations to both light and electronic quantum systems. Here, we demonstrate a single-crystal diamond optomechanical system and show that it allows excitation of diamond mechanical resonances into self-oscillations with amplitude >200 nm . The resulting internal stress field is predicted to allow driving of electron spin transitions of diamond nitrogen-vacancy centers. The mechanical resonances have a quality factor >7 ×105 and can be tuned via nonlinear frequency renormalization, while the optomechanical interface has a 150 nm bandwidth and 9.5 fm /√{Hz } sensitivity. In combination, these features make this system a promising platform for interfacing light, nanomechanics, and electron spins.

  17. Single-Crystal Diamond Nanobeam Waveguide Optomechanics

    Directory of Open Access Journals (Sweden)

    Behzad Khanaliloo

    2015-12-01

    Full Text Available Single-crystal diamond optomechanical devices have the potential to enable fundamental studies and technologies coupling mechanical vibrations to both light and electronic quantum systems. Here, we demonstrate a single-crystal diamond optomechanical system and show that it allows excitation of diamond mechanical resonances into self-oscillations with amplitude >200  nm. The resulting internal stress field is predicted to allow driving of electron spin transitions of diamond nitrogen-vacancy centers. The mechanical resonances have a quality factor >7×10^{5} and can be tuned via nonlinear frequency renormalization, while the optomechanical interface has a 150 nm bandwidth and 9.5  fm/sqrt[Hz] sensitivity. In combination, these features make this system a promising platform for interfacing light, nanomechanics, and electron spins.

  18. Cavity Cooling a Single Charged Levitated Nanosphere

    Science.gov (United States)

    Millen, J.; Fonseca, P. Z. G.; Mavrogordatos, T.; Monteiro, T. S.; Barker, P. F.

    2015-03-01

    Optomechanical cavity cooling of levitated objects offers the possibility for laboratory investigation of the macroscopic quantum behavior of systems that are largely decoupled from their environment. However, experimental progress has been hindered by particle loss mechanisms, which have prevented levitation and cavity cooling in a vacuum. We overcome this problem with a new type of hybrid electro-optical trap formed from a Paul trap within a single-mode optical cavity. We demonstrate a factor of 100 cavity cooling of 400 nm diameter silica spheres trapped in vacuum. This paves the way for ground-state cooling in a smaller, higher finesse cavity, as we show that a novel feature of the hybrid trap is that the optomechanical cooling becomes actively driven by the Paul trap, even for singly charged nanospheres.

  19. Ultrasonic characterization of single drops of liquids

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Dipen N. (Los Alamos, NM)

    1998-01-01

    Ultrasonic characterization of single drops of liquids. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may be adjusted, by surface tension. The surfaces of the interferometer elements may be readily cleansed by a stream of solvent followed by purified air when it is desired to change samples. A single drop of liquid is sufficient for high-quality measurement. Examples of samples which may be investigated using the apparatus and method of the present invention include biological specimens (tear drops; blood and other body fluid samples; samples from tumors, tissues, and organs; secretions from tissues and organs; snake and bee venom, etc.) for diagnostic evaluation, samples in forensic investigations, and detection of drugs in small quantities.

  20. Production of Single W Bosons at LEP

    CERN Document Server

    Acciarri, M; Aguilar-Benítez, M; Ahlen, S P; Alpat, B; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alverson, G; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Baksay, L; Banerjee, S; Banicz, K; Barillère, R; Barone, L; Bartalini, P; Baschirotto, A; Basile, M; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Bilei, G M; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böck, R K; Böhm, A; Borgia, B; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brigljevic, V; Brock, I C; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Busenitz, J K; Button, A M; Cai, X D; Campanelli, M; Capell, M; Cara Romeo, G; Caria, M; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada-Canales, M; Cesaroni, F; Chamizo-Llatas, M; Chan, A; Chang, Y H; Chaturvedi, U K; Chekanov, S V; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chéreau, X J; Chiefari, G; Chien, C Y; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Cohn, H O; Coignet, G; Colijn, A P; Colino, N; Commichau, V; Costantini, S; Cotorobai, F; de la Cruz, B; Csilling, Akos; Dai, T S; D'Alessandro, R; De Asmundis, R; Degré, A; Deiters, K; Della Volpe, D; Denes, P; De Notaristefani, F; DiBitonto, Daryl; Diemoz, M; Van Dierendonck, D N; Di Lodovico, F; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Drago, E; Duchesneau, D; Duinker, P; Durán, I; Dutta, S; Easo, S; Efremenko, Yu V; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Ernenwein, J P; Extermann, Pierre; Fabre, M; Faccini, R; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Fenyi, B; Ferguson, T; Ferroni, F; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Forconi, G; Fredj, L; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gau, S S; Gentile, S; Gheordanescu, N; Giagu, S; Goldfarb, S; Goldstein, J; Gong, Z F; Gougas, Andreas; Gratta, Giorgio; Grünewald, M W; Gupta, V K; Gurtu, A; Gutay, L J; Hartmann, B; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Van Hoek, W C; Hofer, H; Hong, S J; Hoorani, H; Hou, S R; Hu, G; Innocente, Vincenzo; Jenkes, K; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Kasser, A; Khan, R A; Kamrad, D; Kamyshkov, Yu A; Kapustinsky, J S; Karyotakis, Yu; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, D H; Kim, J K; Kim, S C; Kim, Y G; Kinnison, W W; Kirkby, A; Kirkby, D; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Korolko, I; Koutsenko, V F; Krämer, R W; Krenz, W; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lapoint, C; Lassila-Perini, K M; Laurikainen, P; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Leonardi, E; Levchenko, P M; Li Chuan; Lieb, E H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lu, W; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Majumder, G; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mangla, S; Marchesini, P A; Marin, A; Martin, J P; Marzano, F; Massaro, G G G; McNally, D; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mi, Y; Mihul, A; Van Mil, A J W; Mirabelli, G; Mnich, J; Molnár, P; Monteleoni, B; Moore, R; Morganti, S; Moulik, T; Mount, R; Müller, S; Muheim, F; Muijs, A J M; Nagy, E; Nahn, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nippe, A; Nisati, A; Nowak, H; Oh, Yu D; Opitz, H; Organtini, G; Ostonen, R; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Park, H K; Park, I H; Pascale, G; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Peach, D; Pei, Y J; Pensotti, S; Perret-Gallix, D; Petersen, B; Petrak, S; Pevsner, A; Piccolo, D; Pieri, M; Pinto, J C; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Produit, N; Prokofev, D; Prokofiev, D O; Rahal-Callot, G; Rancoita, P G; Rattaggi, M; Raven, G; Razis, P A; Read, K; Ren, D; Rescigno, M; Reucroft, S; Van Rhee, T; Riemann, S; Riles, K; Robohm, A; Rodin, J; Roe, B P; Romero, L; Rosier-Lees, S; Rosselet, P; Van Rossum, W; Roth, S; Rubio, Juan Antonio; Ruschmeier, D; Rykaczewski, H; Salicio, J; Sánchez, E; Sanders, M P; Santocchia, A; Sarakinos, M E; Sarkar, S; Sassowsky, M; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schmitz, P; Scholz, N; Schopper, Herwig Franz; Schotanus, D J; Schwenke, J; Schwering, G; Sciacca, C; Sciarrino, D; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shukla, J; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Sopczak, André; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, H; Stoyanov, B; Strässner, A; Strauch, K; Sudhakar, K; Sultanov, G G; Sun, L Z; Susinno, G F; Suter, H; Swain, J D; Tang, X W; Tauscher, Ludwig; Taylor, L; Ting, Samuel C C; Ting, S M; Tonutti, M; Tonwar, S C; Tóth, J; Tully, C; Tuchscherer, H; Tung, K L; Uchida, Y; Ulbricht, J; Uwer, U; Valente, E; Van de Walle, R T; Vesztergombi, G; Vetlitskii, I; Viertel, Gert M; Vivargent, M; Völkert, R; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, J C; Wang, X L; Wang, Z M; Weber, A; Wittgenstein, F; Wu, S X; Wynhoff, S; Xu, J; Xu, Z Z; Yang, B Z; Yang, C G; Yao, X Y; Ye, J B; Yeh, S C; You, J M; Zalite, A; Zalite, Yu; Zemp, P; Zeng, Y; Zhang, Z; Zhang, Z P; Zhou, B; Zhu, G Y; Zhu, R Y; Zichichi, Antonino; Ziegler, F

    1997-01-01

    We report on the observation of single W boson production in a data sample collected by the L3 detector at LEP2. The signal consists of large missing energy final states with a single energetic lepton or two hadronic jets. The cross-section is measured to be $0.61^{+0.43}_{-0.33} \\pm 0.05 \\; \\rm{pb}$ at the centre of mass energy $\\sqrt{s}=172 \\GeV{}$, consistent with the Standard Model expectation. From this measurement the following limits on the anomalous $\\gamma$WW gauge couplings are derived at 95\\% CL: $\\rm -3.6 < \\Delta \\kappa_\\gamma < 1.5$ and $\\rm -3.6 < \\lambda_\\gamma < 3.6$.