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Sample records for auroras glow regulation

  1. Aurora B interaction of centrosomal Nlp regulates cytokinesis.

    Science.gov (United States)

    Yan, Jie; Jin, Shunqian; Li, Jia; Zhan, Qimin

    2010-12-17

    Cytokinesis is a fundamental cellular process, which ensures equal abscission and fosters diploid progenies. Aberrant cytokinesis may result in genomic instability and cell transformation. However, the underlying regulatory machinery of cytokinesis is largely undefined. Here, we demonstrate that Nlp (Ninein-like protein), a recently identified BRCA1-associated centrosomal protein that is required for centrosomes maturation at interphase and spindle formation in mitosis, also contributes to the accomplishment of cytokinesis. Through immunofluorescent analysis, Nlp is found to localize at midbody during cytokinesis. Depletion of endogenous Nlp triggers aborted division and subsequently leads to multinucleated phenotypes. Nlp can be recruited by Aurora B to the midbody apparatus via their physical association at the late stage of mitosis. Disruption of their interaction induces aborted cytokinesis. Importantly, Nlp is characterized as a novel substrate of Aurora B and can be phosphorylated by Aurora B. The specific phosphorylation sites are mapped at Ser-185, Ser-448, and Ser-585. The phosphorylation at Ser-448 and Ser-585 is likely required for Nlp association with Aurora B and localization at midbody. Meanwhile, the phosphorylation at Ser-185 is vital to Nlp protein stability. Disruptions of these phosphorylation sites abolish cytokinesis and lead to chromosomal instability. Collectively, these observations demonstrate that regulation of Nlp by Aurora B is critical for the completion of cytokinesis, providing novel insights into understanding the machinery of cell cycle progression.

  2. The CUL3-KLHL18 ligase regulates mitotic entry and ubiquitylates Aurora-A.

    Science.gov (United States)

    Moghe, Saili; Jiang, Fei; Miura, Yoshie; Cerny, Ronald L; Tsai, Ming-Ying; Furukawa, Manabu

    2012-02-15

    The cullin-RING family of ubiquitin ligases regulates diverse cellular functions, such as cell cycle control, via ubiquitylation of specific substrates. CUL3 targets its substrates through BTB proteins. Here we show that depletion of CUL3 and the BTB protein KLHL18 causes a delay in mitotic entry. Centrosomal activation of Aurora-A, a kinase whose activity is required for entry into mitosis, is also delayed in depleted cells. Moreover, we identify Aurora-A as a KLHL18-interacting partner. Overexpression of KLHL18 and CUL3 promotes Aurora-A ubiquitylation in vivo, and the CUL3-KLHL18-ROC1 ligase ubiquitylates Aurora-A in vitro. Our study reveals that the CUL3-KLHL18 ligase is required for timely entry into mitosis, as well as for the activation of Aurora-A at centrosomes. We propose that the CUL3-KLHL18 ligase regulates mitotic entry through an Aurora-A-dependent pathway.

  3. The CUL3-KLHL18 ligase regulates mitotic entry and ubiquitylates Aurora-A

    Directory of Open Access Journals (Sweden)

    Saili Moghe

    2012-02-01

    The cullin-RING family of ubiquitin ligases regulates diverse cellular functions, such as cell cycle control, via ubiquitylation of specific substrates. CUL3 targets its substrates through BTB proteins. Here we show that depletion of CUL3 and the BTB protein KLHL18 causes a delay in mitotic entry. Centrosomal activation of Aurora-A, a kinase whose activity is required for entry into mitosis, is also delayed in depleted cells. Moreover, we identify Aurora-A as a KLHL18-interacting partner. Overexpression of KLHL18 and CUL3 promotes Aurora-A ubiquitylation in vivo, and the CUL3-KLHL18-ROC1 ligase ubiquitylates Aurora-A in vitro. Our study reveals that the CUL3-KLHL18 ligase is required for timely entry into mitosis, as well as for the activation of Aurora-A at centrosomes. We propose that the CUL3-KLHL18 ligase regulates mitotic entry through an Aurora-A-dependent pathway.

  4. Regulation of AURORA B function by mitotic checkpoint protein MAD2.

    Science.gov (United States)

    Shandilya, Jayasha; Medler, Kathryn F; Roberts, Stefan G E

    2016-08-17

    Cell cycle checkpoint signaling stringently regulates chromosome segregation during cell division. MAD2 is one of the key components of the spindle and mitotic checkpoint complex that regulates the fidelity of cell division along with MAD1, CDC20, BUBR1, BUB3 and MAD3. MAD2 ablation leads to erroneous attachment of kinetochore-spindle fibers and defective chromosome separation. A potential role for MAD2 in the regulation of events beyond the spindle and mitotic checkpoints is not clear. Together with active spindle assembly checkpoint signaling, AURORA B kinase activity is essential for chromosome condensation as cells enter mitosis. AURORA B phosphorylates histone H3 at serine 10 and serine 28 to facilitate the formation of condensed metaphase chromosomes. In the absence of functional AURORA B cells escape mitosis despite the presence of misaligned chromosomes. In this study we report that silencing of MAD2 results in a drastic reduction of metaphase-specific histone H3 phosphorylation at serine 10 and serine 28. We demonstrate that this is due to mislocalization of AURORA B in the absence of MAD2. Conversely, overexpression of MAD2 concentrated the localization of AURORA B at the metaphase plate and caused hyper-phosphorylation of histone H3. We find that MAD1 plays a minor role in influencing the MAD2-dependent regulation of AURORA B suggesting that the effects of MAD2 on AURORA B are independent of the spindle checkpoint complex. Our findings reveal that, in addition to its role in checkpoint signaling, MAD2 ensures chromosome stability through the regulation of AURORA B.

  5. Aurora A regulates expression of AR-V7 in models of castrate resistant prostate cancer

    Science.gov (United States)

    Jones, Dominic; Noble, Martin; Wedge, Steve R.; Robson, Craig N.; Gaughan, Luke

    2017-01-01

    Androgen receptor variants (AR-Vs) provide a mechanism of therapy evasion in castrate-resistant prostate cancer (CRPC), yet mechanisms of regulation remain largely unknown. Here we investigate the role of Aurora A kinase on AR-Vs in models of CRPC and show depletion of Aurora A reduces AR-V target gene expression. Importantly, knockdown of Aurora A reconfigures splicing of AR pre-mRNA to discriminately down-regulate synthesis of AR-V transcripts, including AR-V7, without effecting full-length AR mRNA; and as a consequence, AR-V-driven proliferation and survival of CRPC cells is markedly reduced. Critically, these effects are reproduced by Aurora A inhibition. We show that Aurora A levels increase in advanced disease and AURKA is an AR-V target gene demonstrating a positive feedback mechanism of androgenic signalling in CRPC. In all, our data suggests that Aurora A plays a pivotal role in regulation of AR-V7 expression and represents a new therapeutic target in CRPC. PMID:28205582

  6. Cell cycle-dependent regulation of Aurora kinase B mRNA by the Microprocessor complex.

    Science.gov (United States)

    Jung, Eunsun; Seong, Youngmo; Seo, Jae Hong; Kwon, Young-Soo; Song, Hoseok

    2014-03-28

    Aurora kinase B regulates the segregation of chromosomes and the spindle checkpoint during mitosis. In this study, we showed that the Microprocessor complex, which is responsible for the processing of the primary transcripts during the generation of microRNAs, destabilizes the mRNA of Aurora kinase B in human cells. The Microprocessor-mediated cleavage kept Aurora kinase B at a low level and prevented premature entrance into mitosis. The cleavage was reduced during mitosis leading to the accumulation of Aurora kinase B mRNA and protein. In addition to Aurora kinase B mRNA, the processing of other primary transcripts of miRNAs were also decreased during mitosis. We found that the cleavage was dependent on an RNA helicase, DDX5, and the association of DDX5 and DDX17 with the Microprocessor was reduced during mitosis. Thus, we propose a novel mechanism by which the Microprocessor complex regulates stability of Aurora kinase B mRNA and cell cycle progression.

  7. Aurora B regulates spindle bipolarity in meiosis in vertebrate oocytes.

    Science.gov (United States)

    Shao, Hua; Ma, Chunqi; Zhang, Xuan; Li, Ruizhen; Miller, Ann L; Bement, William M; Liu, X Johné

    2012-07-15

    Aurora B (Aur-B) plays multiple roles in mitosis, of which the best known are to ensure bi-orientation of sister chromatids by destabilizing incorrectly attached kinetochore microtubules and to participate in cytokinesis. Studies in Xenopus egg extracts, however, have indicated that Aur-B and the chromosome passenger complex play an important role in stabilizing chromosome-associated spindle microtubules. Aur-B stabilizes spindle microtubules in the egg extracts by inhibiting the catastrophe kinesin MCAK. Whether or not Aur-B plays a similar role in intact oocytes remains unknown. Here we have employed a dominant-negative Aur-B mutant (Aur-B122R, in which the ATP-binding lysine(122) is replaced with arginine) to investigate the function of Aur-B in spindle assembly in Xenopus oocytes undergoing meiosis. Overexpression of Aur-B122R results in short bipolar spindles or monopolar spindles, with higher concentrations of Aur-B122R producing mostly the latter. Simultaneous inhibition of MCAK translation in oocytes overexpressing Aur-B122R results in suppression of monopolar phenotype, suggesting that Aur-B regulates spindle bipolarity by inhibiting MCAK. Furthermore, recombinant MCAK-4A protein, which lacks all four Aur-B phosphoryaltion sites and is therefore insensitive to Aur-B inhibition but not wild-type MCAK, recapitulated the monopolar phenotype in the oocytes. These results suggest that in vertebrate oocytes that lack centrosomes, one major function of Aur-B is to stabilize chromosome-associated spindle microtubules to ensure spindle bipolarity.

  8. Function and regulation of Aurora/Ipl1p kinase family in cell division

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    During mitosis, the parent cell distributes its genetic materials equally into two daughter cells through chromosome segregation, a complex movements orchestrated by mitotic kinases and its effector proteins.Faithful chromosome segregation and cytokinesis ensure that each daughter cell receives a full copy of genetic materials of parent cell. Defects in these processes can lead to aneuploidy or polyploidy. Aurora/Ipl1p fanily,a class of conserved serine/threonine kinases, plays key roles in chromosome segregation and cytokinesis.This article highlights the function and regulation of Aurora/Ipl1p family in mitosis and provides potential links between aberrant regulation of Aurora/Ipl1p kinases and pathogenesis of human cancer.

  9. Tripolin A, a novel small-molecule inhibitor of aurora A kinase, reveals new regulation of HURP's distribution on microtubules.

    Directory of Open Access Journals (Sweden)

    Iliana A Kesisova

    Full Text Available Mitotic regulators exhibiting gain of function in tumor cells are considered useful cancer therapeutic targets for the development of small-molecule inhibitors. The human Aurora kinases are a family of such targets. In this study, from a panel of 105 potential small-molecule inhibitors, two compounds Tripolin A and Tripolin B, inhibited Aurora A kinase activity in vitro. In human cells however, only Tripolin A acted as an Aurora A inhibitor. We combined in vitro, in vivo single cell and in silico studies to demonstrate the biological action of Tripolin A, a non-ATP competitive inhibitor. Tripolin A reduced the localization of pAurora A on spindle microtubules (MTs, affected centrosome integrity, spindle formation and length, as well as MT dynamics in interphase, consistent with Aurora A inhibition by RNAi or other specific inhibitors, such as MLN8054 or MLN8237. Interestingly, Tripolin A affected the gradient distribution towards the chromosomes, but not the MT binding of HURP (Hepatoma Up-Regulated Protein, a MT-associated protein (MAP and substrate of the Aurora A kinase. Therefore Tripolin A reveals a new way of regulating mitotic MT stabilizers through Aurora A phosphorylation. Tripolin A is predicted to bind Aurora A similarly but not identical to MLN8054, therefore it could be used to dissect pathways orchestrated by Aurora kinases as well as a scaffold for further inhibitor development.

  10. Tripolin A, a novel small-molecule inhibitor of aurora A kinase, reveals new regulation of HURP's distribution on microtubules.

    Science.gov (United States)

    Kesisova, Iliana A; Nakos, Konstantinos C; Tsolou, Avgi; Angelis, Dimitrios; Lewis, Joe; Chatzaki, Aikaterini; Agianian, Bogos; Giannis, Athanassios; Koffa, Maria D

    2013-01-01

    Mitotic regulators exhibiting gain of function in tumor cells are considered useful cancer therapeutic targets for the development of small-molecule inhibitors. The human Aurora kinases are a family of such targets. In this study, from a panel of 105 potential small-molecule inhibitors, two compounds Tripolin A and Tripolin B, inhibited Aurora A kinase activity in vitro. In human cells however, only Tripolin A acted as an Aurora A inhibitor. We combined in vitro, in vivo single cell and in silico studies to demonstrate the biological action of Tripolin A, a non-ATP competitive inhibitor. Tripolin A reduced the localization of pAurora A on spindle microtubules (MTs), affected centrosome integrity, spindle formation and length, as well as MT dynamics in interphase, consistent with Aurora A inhibition by RNAi or other specific inhibitors, such as MLN8054 or MLN8237. Interestingly, Tripolin A affected the gradient distribution towards the chromosomes, but not the MT binding of HURP (Hepatoma Up-Regulated Protein), a MT-associated protein (MAP) and substrate of the Aurora A kinase. Therefore Tripolin A reveals a new way of regulating mitotic MT stabilizers through Aurora A phosphorylation. Tripolin A is predicted to bind Aurora A similarly but not identical to MLN8054, therefore it could be used to dissect pathways orchestrated by Aurora kinases as well as a scaffold for further inhibitor development.

  11. Aurora A kinase regulates proper spindle positioning in C. elegans and in human cells.

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    Kotak, Sachin; Afshar, Katayon; Busso, Coralie; Gönczy, Pierre

    2016-08-01

    Accurate spindle positioning is essential for error-free cell division. The one-cell Caenorhabditis elegans embryo has proven instrumental for dissecting mechanisms governing spindle positioning. Despite important progress, how the cortical forces that act on astral microtubules to properly position the spindle are modulated is incompletely understood. Here, we report that the PP6 phosphatase PPH-6 and its associated subunit SAPS-1, which positively regulate pulling forces acting on spindle poles, associate with the Aurora A kinase AIR-1 in C. elegans embryos. We show that acute inactivation of AIR-1 during mitosis results in excess pulling forces on astral microtubules. Furthermore, we uncover that AIR-1 acts downstream of PPH-6-SAPS-1 in modulating spindle positioning, and that PPH-6-SAPS-1 negatively regulates AIR-1 localization at the cell cortex. Moreover, we show that Aurora A and the PP6 phosphatase subunit PPP6C are also necessary for spindle positioning in human cells. There, Aurora A is needed for the cortical localization of NuMA and dynein during mitosis. Overall, our work demonstrates that Aurora A kinases and PP6 phosphatases have an ancient function in modulating spindle positioning, thus contributing to faithful cell division.

  12. Dynamic phosphorylation of Histone Deacetylase 1 by Aurora kinases during mitosis regulates zebrafish embryos development

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    Loponte, Sara; Segré, Chiara V.; Senese, Silvia; Miccolo, Claudia; Santaguida, Stefano; Deflorian, Gianluca; Citro, Simona; Mattoscio, Domenico; Pisati, Federica; Moser, Mirjam A.; Visintin, Rosella; Seiser, Christian; Chiocca, Susanna

    2016-01-01

    Histone deacetylases (HDACs) catalyze the removal of acetyl molecules from histone and non-histone substrates playing important roles in chromatin remodeling and control of gene expression. Class I HDAC1 is a critical regulator of cell cycle progression, cellular proliferation and differentiation during development; it is also regulated by many post-translational modifications (PTMs). Herein we characterize a new mitosis-specific phosphorylation of HDAC1 driven by Aurora kinases A and B. We show that this phosphorylation affects HDAC1 enzymatic activity and it is critical for the maintenance of a proper proliferative and developmental plan in a complex organism. Notably, we find that Aurora-dependent phosphorylation of HDAC1 regulates histone acetylation by modulating the expression of genes directly involved in the developing zebrafish central nervous system. Our data represent a step towards the comprehension of HDAC1 regulation by its PTM code, with important implications in unravelling its roles both in physiology and pathology. PMID:27458029

  13. A translational regulator, PUM2, promotes both protein stability and kinase activity of Aurora-A.

    Directory of Open Access Journals (Sweden)

    Yei-Hsuan Huang

    Full Text Available Aurora-A, a centrosomal serine-threonine kinase, orchestrates several key aspects of cell division. However, the regulatory pathways for the protein stability and kinase activity of Aurora-A are still not completely understood. In this study, PUM2, an RNA-binding protein, is identified as a novel substrate and interacting protein of Aurora-A. Overexpression of the PUM2 mutant which fails to interact with Aurora-A, and depletion of PUM2 result in a decrease in the amount of Aurora-A. PUM2 physically binds to the D-box of Aurora-A, which is recognized by APC/C(Cdh1. Overexpression of PUM2 prevents ubiquitination and enhances the protein stability of Aurora-A, suggesting that PUM2 protects Aurora-A from APC/C(Cdh1-mediated degradation. Moreover, association of PUM2 with Aurora-A not only makes Aurora-A more stable but also enhances the kinase activity of Aurora-A. Our study suggests that PUM2 plays two different but important roles during cell cycle progression. In interphase, PUM2 localizes in cytoplasm and plays as translational repressor through its RNA binding domain. However, in mitosis, PUM2 physically associates with Aurora-A to ensure enough active Aurora-A at centrosomes for mitotic entry. This is the first time to reveal the moonlight role of PUM2 in mitosis.

  14. Interdomain allosteric regulation of Polo kinase by Aurora B and Map205 is required for cytokinesis.

    Science.gov (United States)

    Kachaner, David; Pinson, Xavier; El Kadhi, Khaled Ben; Normandin, Karine; Talje, Lama; Lavoie, Hugo; Lépine, Guillaume; Carréno, Sébastien; Kwok, Benjamin H; Hickson, Gilles R; Archambault, Vincent

    2014-10-27

    Drosophila melanogaster Polo and its human orthologue Polo-like kinase 1 fulfill essential roles during cell division. Members of the Polo-like kinase (Plk) family contain an N-terminal kinase domain (KD) and a C-terminal Polo-Box domain (PBD), which mediates protein interactions. How Plks are regulated in cytokinesis is poorly understood. Here we show that phosphorylation of Polo by Aurora B is required for cytokinesis. This phosphorylation in the activation loop of the KD promotes the dissociation of Polo from the PBD-bound microtubule-associated protein Map205, which acts as an allosteric inhibitor of Polo kinase activity. This mechanism allows the release of active Polo from microtubules of the central spindle and its recruitment to the site of cytokinesis. Failure in Polo phosphorylation results in both early and late cytokinesis defects. Importantly, the antagonistic regulation of Polo by Aurora B and Map205 in cytokinesis reveals that interdomain allosteric mechanisms can play important roles in controlling the cellular functions of Plks.

  15. Aurora B is regulated by the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway and is a valuable potential target in melanoma cells.

    Science.gov (United States)

    Bonet, Caroline; Giuliano, Sandy; Ohanna, Mickaël; Bille, Karine; Allegra, Maryline; Lacour, Jean-Philippe; Bahadoran, Philippe; Rocchi, Stéphane; Ballotti, Robert; Bertolotto, Corine

    2012-08-24

    Metastatic melanoma is a deadly skin cancer and is resistant to almost all existing treatment. Vemurafenib, which targets the BRAFV600E mutation, is one of the drugs that improves patient outcome, but the patients next develop secondary resistance and a return to cancer. Thus, new therapeutic strategies are needed to treat melanomas and to increase the duration of v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) inhibitor response. The ERK pathway controls cell proliferation, and Aurora B plays a pivotal role in cell division. Here, we confirm that Aurora B is highly expressed in metastatic melanoma cells and that Aurora B inhibition triggers both senescence-like phenotypes and cell death in melanoma cells. Furthermore, we show that the BRAF/ERK axis controls Aurora B expression at the transcriptional level, likely through the transcription factor FOXM1. Our results provide insight into the mechanism of Aurora B regulation and the first molecular basis of Aurora B regulation in melanoma cells. The inhibition of Aurora B expression that we observed in vemurafenib-sensitive melanoma cells was rescued in cells resistant to this drug. Consistently, these latter cells remain sensitive to the effect of the Aurora B inhibitor. Noteworthy, wild-type BRAF melanoma cells are also sensitive to Aurora B inhibition. Collectively, our findings, showing that Aurora B is a potential target in melanoma cells, particularly in those vemurafenib-resistant, may open new avenues to improve the treatment of metastatic melanoma.

  16. Stathmin and microtubules regulate mitotic entry in HeLa cells by controlling activation of both Aurora kinase A and Plk1.

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    Silva, Victoria C; Cassimeris, Lynne

    2013-12-01

    Depletion of stathmin, a microtubule (MT) destabilizer, delays mitotic entry by ∼4 h in HeLa cells. Stathmin depletion reduced the activity of CDC25 and its upstream activators, Aurora A and Plk1. Chemical inhibition of both Aurora A and Plk1 was sufficient to delay mitotic entry by 4 h, while inhibiting either kinase alone did not cause a delay. Aurora A and Plk1 are likely regulated downstream of stathmin, because the combination of stathmin knockdown and inhibition of Aurora A and Plk1 was not additive and again delayed mitotic entry by 4 h. Aurora A localization to the centrosome required MTs, while stathmin depletion spread its localization beyond that of γ-tubulin, indicating an MT-dependent regulation of Aurora A activation. Plk1 was inhibited by excess stathmin, detected in in vitro assays and cells overexpressing stathmin-cyan fluorescent protein. Recruitment of Plk1 to the centrosome was delayed in stathmin-depleted cells, independent of MTs. It has been shown that depolymerizing MTs with nocodazole abrogates the stathmin-depletion induced cell cycle delay; in this study, depolymerization with nocodazole restored Plk1 activity to near normal levels, demonstrating that MTs also contribute to Plk1 activation. These data demonstrate that stathmin regulates mitotic entry, partially via MTs, to control localization and activation of both Aurora A and Plk1.

  17. Ewing sarcoma EWS protein regulates midzone formation by recruiting Aurora B kinase to the midzone.

    Science.gov (United States)

    Park, Hyewon; Turkalo, Timothy K; Nelson, Kayla; Folmsbee, Stephen Sai; Robb, Caroline; Roper, Brittany; Azuma, Mizuki

    2014-01-01

    Ewing sarcoma is a malignant bone cancer that primarily occurs in children and adolescents. Eighty-five percent of Ewing sarcoma is characterized by the presence of the aberrant chimeric EWS/FLI1 fusion gene. Previously, we demonstrated that an interaction between EWS/FLI1 and wild-type EWS led to the inhibition of EWS activity and mitotic dysfunction. Although defective mitosis is considered to be a critical step in cancer initiation, it is unknown how interference with EWS contributes to Ewing sarcoma formation. Here, we demonstrate that EWS/FLI1- and EWS-knockdown cells display a high incidence of defects in the midzone, a midline structure located between segregating chromatids during anaphase. Defects in the midzone can lead to the failure of cytokinesis and can result in the induction of aneuploidy. The similarity among the phenotypes of EWS/FLI1- and EWS siRNA-transfected HeLa cells points to the inhibition of EWS as the key mechanism for the induction of midzone defects. Supporting this observation, the ectopic expression of EWS rescues the high incidence of midzone defects observed in Ewing sarcoma A673 cells. We discovered that EWS interacts with Aurora B kinase, and that EWS is also required for recruiting Aurora B to the midzone. A domain analysis revealed that the R565 in the RGG3 domain of EWS is essential for both Aurora B interaction and the recruitment of Aurora B to the midzone. Here, we propose that the impairment of EWS-dependent midzone formation via the recruitment of Aurora B is a potential mechanism of Ewing sarcoma development.

  18. The mitosis-regulating and protein-protein interaction activities of astrin are controlled by aurora-A-induced phosphorylation.

    Science.gov (United States)

    Chiu, Shao-Chih; Chen, Jo-Mei Maureen; Wei, Tong-You Wade; Cheng, Tai-Shan; Wang, Ya-Hui Candice; Ku, Chia-Feng; Lian, Chiao-Hsuan; Liu, Chun-Chih Jared; Kuo, Yi-Chun; Yu, Chang-Tze Ricky

    2014-09-01

    Cells display dramatic morphological changes in mitosis, where numerous factors form regulatory networks to orchestrate the complicated process, resulting in extreme fidelity of the segregation of duplicated chromosomes into two daughter cells. Astrin regulates several aspects of mitosis, such as maintaining the cohesion of sister chromatids by inactivating Separase and stabilizing spindle, aligning and segregating chromosomes, and silencing spindle assembly checkpoint by interacting with Src kinase-associated phosphoprotein (SKAP) and cytoplasmic linker-associated protein-1α (CLASP-1α). To understand how Astrin is regulated in mitosis, we report here that Astrin acts as a mitotic phosphoprotein, and Aurora-A phosphorylates Astrin at Ser(115). The phosphorylation-deficient mutant Astrin S115A abnormally activates spindle assembly checkpoint and delays mitosis progression, decreases spindle stability, and induces chromosome misalignment. Mechanistic analyses reveal that Astrin phosphorylation mimicking mutant S115D, instead of S115A, binds and induces ubiquitination and degradation of securin, which sequentially activates Separase, an enzyme required for the separation of sister chromatids. Moreover, S115A fails to bind mitosis regulators, including SKAP and CLASP-1α, which results in the mitotic defects observed in Astrin S115A-transfected cells. In conclusion, Aurora-A phosphorylates Astrin and guides the binding of Astrin to its cellular partners, which ensures proper progression of mitosis.

  19. Sgo1 regulates both condensin and Ipl1/Aurora B to promote chromosome biorientation.

    Directory of Open Access Journals (Sweden)

    Karolina Peplowska

    2014-06-01

    Full Text Available Correct chromosome segregation is essential in order to prevent aneuploidy. To segregate sister chromatids equally to daughter cells, the sisters must attach to microtubules emanating from opposite spindle poles. This so-called biorientation manifests itself by increased tension and conformational changes across kinetochores and pericentric chromatin. Tensionless attachments are dissolved by the activity of the conserved mitotic kinase Aurora B/Ipl1, thereby promoting the formation of correctly attached chromosomes. Recruitment of the conserved centromeric protein shugoshin is essential for biorientation, but its exact role has been enigmatic. Here, we identify a novel function of shugoshin (Sgo1 in budding yeast that together with the protein phosphatase PP2A-Rts1 ensures localization of condensin to the centromeric chromatin in yeast Saccharomyces cerevisiae. Failure to recruit condensin results in an abnormal conformation of the pericentric region and impairs the correction of tensionless chromosome attachments. Moreover, we found that shugoshin is required for maintaining Aurora B/Ipl1 localization on kinetochores during metaphase. Thus, shugoshin has a dual function in promoting biorientation in budding yeast: first, by its ability to facilitate condensin recruitment it modulates the conformation of the pericentric chromatin. Second, shugoshin contributes to the maintenance of Aurora B/Ipl1 at the kinetochore during gradual establishment of bipolarity in budding yeast mitosis. Our findings identify shugoshin as a versatile molecular adaptor that governs chromosome biorientation.

  20. Aurora A Kinase Regulates Mammary Epithelial Cell Fate by Determining Mitotic Spindle Orientation in a Notch-Dependent Manner

    Directory of Open Access Journals (Sweden)

    Joseph L. Regan

    2013-07-01

    Full Text Available Cell fate determination in the progeny of mammary epithelial stem/progenitor cells remains poorly understood. Here, we have examined the role of the mitotic kinase Aurora A (AURKA in regulating the balance between basal and luminal mammary lineages. We find that AURKA is highly expressed in basal stem cells and, to a lesser extent, in luminal progenitors. Wild-type AURKA expression promoted luminal cell fate, but expression of an S155R mutant reduced proliferation, promoted basal fate, and inhibited serial transplantation. The mechanism involved regulation of mitotic spindle orientation by AURKA and the positioning of daughter cells after division. Remarkably, this was NOTCH dependent, as NOTCH inhibitor blocked the effect of wild-type AURKA expression on spindle orientation and instead mimicked the effect of the S155R mutant. These findings directly link AURKA, NOTCH signaling, and mitotic spindle orientation and suggest a mechanism for regulating the balance between luminal and basal lineages in the mammary gland.

  1. What's so Bor(a)ing about Aurora-A activation?

    Science.gov (United States)

    Wiese, Christiane; O'Brien, Lori L

    2006-08-01

    Aurora-A kinases are highly conserved mitotic kinases required for cell division. The regulation of Aurora-A activity is less highly conserved and currently poorly understood. Work by Knoblich and coworkers in this issue of Developmental Cell identifies the conserved protein, Aurora Borealis (Bora), as a key regulator of Aurora-A activity during mitosis.

  2. Aurorae: The earliest datable observation of the aurora borealis

    Science.gov (United States)

    Stephenson, F. Richard; Willis, David M.; Hallinan, Thomas J.

    2004-12-01

    The Late Babylonian astronomical texts, discovered at the site of Babylon (32.5°N, 44.4°E) more than a century ago, contain what is probably the earliest reliable account of the aurora borealis. A clay tablet recording numerous celestial observations made by the official astronomers during the 37th year of King Nebuchadnezzar II (568/567 BC) describes an unusual ``red glow'' in the sky at night; the exact date of this observation corresponds to the night of 12/13 March in 567 BC. The most likely interpretation of the phenomenon is an auroral display. This event occurred several centuries before the first clearly identifiable observation of the aurora from elsewhere in the world, namely China in 193 BC. The Babylonian auroral observation is remarkable in the sense that it is one of a series of carefully recorded astronomical observations, for each of which the year, month and day are known precisely. This observation occurred at a time when the geomagnetic (dipole) latitude of Babylon was about 41°N compared with the present value of 27.5°N, suggesting a higher auroral incidence at Babylon in 567 BC than at present.

  3. Aurora kinases in childhood acute leukemia: The promise of aurora B as therapeutic target

    NARCIS (Netherlands)

    S.A. Hartsink-Segers (S.); C.M. Zwaan (Michel); C. Exalto (Carla); M.W.J. Luijendijk (M. W J); V. Calvert (V.); E.F. Petricoin (Emanuel F.); W.E. Evans (William); D. Reinhardt (Dirk); V. de Haas (Valerie); M. Hedtjärn (M.); B.R. Hansen (B.); T. Koch (T.); H.N. Caron (Huib); R. Pieters (Rob); M.L. den Boer (Monique)

    2013-01-01

    textabstractWe investigated the effects of targeting the mitotic regulators aurora kinase A and B in pediatric acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Aurora protein expression levels in pediatric ALL and AML patient samples were determined by western blot and reverse ph

  4. Control of centrin stability by Aurora A.

    Directory of Open Access Journals (Sweden)

    Kara B Lukasiewicz

    Full Text Available Aurora A is an oncogenic serine/threonine kinase which can cause cell transformation and centrosome amplification when over-expressed. Human breast tumors show excess Aurora A and phospho-centrin in amplified centrosomes. Here, we show that Aurora A mediates the phosphorylation of and localizes with centrin at the centrosome, with both proteins reaching maximum abundance from prophase through metaphase, followed by their precipitous loss in late stages of mitosis. Over-expression of Aurora A results in excess phospho-centrin and centrosome amplification. In contrast, centrosome amplification is not seen in cells over-expressing Aurora A in the presence of a recombinant centrin mutant lacking the serine phosphorylation site at residue 170. Expression of a kinase dead Aurora A results in a decrease in mitotic index and abrogation of centrin phosphorylation. Finally, a recombinant centrin mutation that mimics centrin phosphorylation increases centrin's stability against APC/C-mediated proteasomal degradation. Taken together, these results suggest that the stability of centrin is regulated in part by Aurora A, and that excess phosphorylated centrin may promote centrosome amplification in cancer.

  5. Look out, aurorae about!

    Science.gov (United States)

    Wild, Jim

    2006-02-01

    Myths and legends abound concerning the aurora borealis; observations, at least in the UK, are considerably more rare, yet people continue to be interested in observing them on the few times a year they are visible. AuroraWatch hopes to boost this interest by providing an email alert service that, since 2000, has used real-time information from a network of magnetometers to assess when aurorae might be visible. Alerts can be sent to mobile phones as well as by conventional email, and have already enabled many people to see this beautiful natural phenomenon.

  6. Aurora final report

    Energy Technology Data Exchange (ETDEWEB)

    Robert, Dross; Amedeo, Conti

    2013-12-06

    Final Technical report detailing the work done by Nuvera and its partners to fulfill the goals of the program "Transport Studies Enabling Efficiency Optimization of Cost-Competitive Fuel Cell Stacks" (a.k.a. AURORA)

  7. The dynamic aurora

    Energy Technology Data Exchange (ETDEWEB)

    Akasofu, Syunichi (Univ. of Alaska, Fairbanks (USA))

    1989-05-01

    Auroral physicists today know that auroras are lights emitted when atoms and molecules in the ionosphere are struck by electrons blowing in from the sun. The apparent motion of the auroral curtain is caused not by atmospheric turbulence but by changes in the electromagnetic conditions that propel the electrons, just as motion on a television screen is an illusion created by changes in the magnetic field that directs electrons from a cathode tube onto the screen. In the case of the aurora, what serves as the cathode tube Where is its power supply Why does that power seem to fluctuate from time to time, causing the aurora to ebb and flow across the polar sky More than 20 years ago it was determined that auroral emissions occur because the ionosphere is bombarded by electron beams generated by a complex interaction between the solar wind and the earth's magnetic envelope. The geomagnetic nature of the aurora can be seen clearly from outer space. Centered on each of the geomagnetic poles is a great luminous oval that is a permanent feature of the planet. The one around the North Pole is the aurora borealis. Its counterpart in the south is the aurora australis. The authors and his colleagues have now found a numerical relation between the solar wind and the generation of the power that drives the aurora, as well as other disturbances of the geomagnetic field. They are also gaining a better idea of how the sun's activity affects the solar wind. This progress raises the interesting possibility of developing a computer method to predict the intensity of auroral activity. Because auroras can interfere significantly with radio and satellite communications, as well as with power lines and some defense systems, the ability to predict auroral intensity has become increasingly important as human activity expands into polar regions and into space.

  8. AuroraMAX!

    Science.gov (United States)

    Donovan, E.; Spanswick, E. L.; Chicoine, R.; Pugsley, J.; Langlois, P.

    2011-12-01

    AuroraMAX is a public outreach and education initiative that brings auroral images to the public in real time. AuroraMAX utilizes an observing station located just outside Yellowknife, Canada. The station houses a digital All-Sky Imager (ASI) that collects full-colour images of the night sky every six seconds. These images are then transmitted via satellite internet to our web server, where they are made instantly available to the public. Over the last two years this program has rapidly become one of the most successful outreach programs in the history of Space Science in Canada, with hundreds of thousands of distinct visitors to the CSA AuroraMAX website, thousands of followers on social media, and hundreds of newspaper, magazine, radio, and television spots. Over the next few years, the project will expand to include a high-resolution SLR delivering real-time auroral images (also from Yellowknife), as well as a program where astronauts on the ISS will take pictures of the aurora with a handheld SLR. The objectives of AuroraMAX are public outreach and education. The ASI design, operation, and software were based on infrastructure that was developed for the highly successful ASI component of the NASA THEMIS mission as well as the Canadian Space Agency (CSA) Canadian GeoSpace Monitoring (CGSM) program. So from an education and public outreach perspective, AuroraMAX is a single camera operating in the Canadian north. On the other hand, AuroraMAX is one of nearly 40 All-Sky Imagers that are operating across North America. The AuroraMAX camera produces data that is seamlessly integrated with the CGSM ASI data, and made widely available to the Space Science community through open-access web and FTP sites. One of our objectives in the next few years is to incorporate some of the data from the THEMIS and CGSM imagers into the AuroraMAX system, to maximize viewing opportunities and generate more real-time data for public outreach. This is an exemplar of a program that

  9. Multifunctional human transcriptional coactivator protein PC4 is a substrate of Aurora kinases and activates the Aurora enzymes.

    Science.gov (United States)

    Dhanasekaran, Karthigeyan; Kumari, Sujata; Boopathi, Ramachandran; Shima, Hiroki; Swaminathan, Amrutha; Bachu, Mahesh; Ranga, Udaykumar; Igarashi, Kazuhiko; Kundu, Tapas K

    2016-03-01

    Positive coactivator 4 (PC4), a human transcriptional coactivator, is involved in diverse processes like chromatin organization and transcription regulation. It is hyperphosphorylated during mitosis, with unknown significance. For the first time, we demonstrate the function of PC4 outside the nucleus upon nuclear envelope breakdown. A fraction of PC4 associates with Aurora A and Aurora B and undergoes phosphorylation, following which PC4 activates both Aurora A and B to sustain optimal kinase activity to maintain the phosphorylation gradient for the proper functioning of the mitotic machinery. This mitotic role is evident in PC4 knockdown cells where the defects are rescued only by the catalytically active Aurora kinases, but not the kinase-dead mutants. Similarly, the PC4 phosphodeficient mutant failed to rescue such defects. Hence, our observations establish a novel mitotic function of PC4 that might be dependent on Aurora kinase-mediated phosphorylation.

  10. Imaging Sunlit Aurora from Balloon

    Science.gov (United States)

    Lummerzheim, D.; Zhou, X.

    2012-12-01

    Since 1892 when aurora was first imaged by Martin Brendel, useful auroral images have been obtained only when the aurora is in darkness. While UV imagers onboard satellite provide global auroral dynamics, the sunlit aurora in the UV band is overwhelmed by the UV airglow that has the same wavelengths with the UV auroral emissions. The visible band imaging is feasible only when the aurora is in darkness to avoid the sunlight contamination. However, sunlit aurora (such as dayside aurora) is closely related to the solar wind - magnetosphere - ionosphere coupling. In addition, limited land area has badly restricted the capability of imaging dayside aurora from the northern hemisphere and nightside aurora from the southern hemisphere. We have confirmed that sunlit aurora can be imaged using a near-infrared (NIR) camera on board the balloon platform flying in Antarctica or Arctic. This method provides a unique capability for dayside and conjugate auroral investigations. Scientific questions that can be addressed by such observations include how does the dayside aurora respond to solar wind transient variations? Are auroras hemispherically symmetric? Are auroral forms and their variations under sunlight the same as those in darkness? etc. The new method is also cost effective comparing to space-borne imagers, and offers capabilities not obtainable from space and the ground. With the accomplishment of identifying auroral dynamics in sunlight and darkness, in the south and north simultaneously, our knowledge and understanding of auroral phenomenon and its causes will be expanded.

  11. KNL1 facilitates phosphorylation of outer kinetochore proteins by promoting Aurora B kinase activity.

    Science.gov (United States)

    Caldas, Gina V; DeLuca, Keith F; DeLuca, Jennifer G

    2013-12-23

    Aurora B kinase phosphorylates kinetochore proteins during early mitosis, increasing kinetochore–microtubule (MT) turnover and preventing premature stabilization of kinetochore–MT attachments. Phosphorylation of kinetochore proteins during late mitosis is low, promoting attachment stabilization, which is required for anaphase onset. The kinetochore protein KNL1 recruits Aurora B–counteracting phosphatases and the Aurora B–targeting factor Bub1, yet the consequences of KNL1 depletion on Aurora B phospho-regulation remain unknown. Here, we demonstrate that the KNL1 N terminus is essential for Aurora B activity at kinetochores. This region of KNL1 is also required for Bub1 kinase activity at kinetochores, suggesting that KNL1 promotes Aurora B activity through Bub1-mediated Aurora B targeting. However, ectopic targeting of Aurora B to kinetochores does not fully rescue Aurora B activity in KNL1-depleted cells, suggesting KNL1 influences Aurora B activity through an additional pathway. Our findings establish KNL1 as a requirement for Aurora B activity at kinetochores and for wild-type kinetochore–MT attachment dynamics.

  12. San Huang Decoction Promotes Apoptosis of Breast Cancer Cells Through Regulating Aurora Kinase A%三黄煎剂调节Aurora激酶A促进乳腺癌细胞凋亡的实验研究

    Institute of Scientific and Technical Information of China (English)

    许岩磊; 陈曦琰; 陈绪; 卞卫和; 姚昶; 朱小纾; 陈佳静

    2015-01-01

    MDA?MB?231 cell lines in a dose?dependent manner.Consistent with cellular resultsSan Huang decoction treatment signifi-cantly increased the apoptosis?related protein level of cleaved?PARPc?PARPcleaved?Caspase 3c?Caspase 3and Baxdown ?regulated Bcl?2 in a does?dependent manner.MeanwhileSan Huang decoction decreased the mRNA and protein level of Auro-ra A and increased those of p53 in a does?dependent manner.CONCLUSION San Huang decoction at the first time was able to promote the apoptosis of breast cancer cells via inducing the suppression of Aurora A.

  13. Tabletop Aurora Demonstrator.

    Science.gov (United States)

    Zaffo, Peter Alfred

    1991-01-01

    A simple apparatus for studying various forms of the aurora borealis on a miniature scale can be constructed from a neon-storage flask, aluminum tape, a cardboard box, and a small piezoelectric ion gun of the type used to neutralize static charges on phonograph records. (PR)

  14. Phosphorylation of MAP65-1 by Arabidopsis Aurora Kinases Is Required for Efficient Cell Cycle Progression1[OPEN

    Science.gov (United States)

    Weimer, Annika K.; Stoppin-Mellet, Virginie; Kosetsu, Ken; Cedeño, Cesyen; Jaquinod, Michel; Njo, Maria; De Milde, Liesbeth; Tompa, Peter; Inzé, Dirk; Beeckman, Tom; Vantard, Marylin

    2017-01-01

    Aurora kinases are key effectors of mitosis. Plant Auroras are functionally divided into two clades. The alpha Auroras (Aurora1 and Aurora2) associate with the spindle and the cell plate and are implicated in controlling formative divisions throughout plant development. The beta Aurora (Aurora3) localizes to centromeres and likely functions in chromosome separation. In contrast to the wealth of data available on the role of Aurora in other kingdoms, knowledge on their function in plants is merely emerging. This is exemplified by the fact that only histone H3 and the plant homolog of TPX2 have been identified as Aurora substrates in plants. Here we provide biochemical, genetic, and cell biological evidence that the microtubule-bundling protein MAP65-1—a member of the MAP65/Ase1/PRC1 protein family, implicated in central spindle formation and cytokinesis in animals, yeasts, and plants—is a genuine substrate of alpha Aurora kinases. MAP65-1 interacts with Aurora1 in vivo and is phosphorylated on two residues at its unfolded tail domain. Its overexpression and down-regulation antagonistically affect the alpha Aurora double mutant phenotypes. Phospho-mutant analysis shows that Aurora contributes to the microtubule bundling capacity of MAP65-1 in concert with other mitotic kinases. PMID:27879390

  15. Evolutionary relationships of Aurora kinases: Implications for model organism studies and the development of anti-cancer drugs

    Directory of Open Access Journals (Sweden)

    Patrick Denis R

    2004-10-01

    Full Text Available Abstract Background As key regulators of mitotic chromosome segregation, the Aurora family of serine/threonine kinases play an important role in cell division. Abnormalities in Aurora kinases have been strongly linked with cancer, which has lead to the recent development of new classes of anti-cancer drugs that specifically target the ATP-binding domain of these kinases. From an evolutionary perspective, the species distribution of the Aurora kinase family is complex. Mammals uniquely have three Aurora kinases, Aurora-A, Aurora-B, and Aurora-C, while for other metazoans, including the frog, fruitfly and nematode, only Aurora-A and Aurora-B kinases are known. The fungi have a single Aurora-like homolog. Based on the tacit assumption of orthology to human counterparts, model organism studies have been central to the functional characterization of Aurora kinases. However, the ortholog and paralog relationships of these kinases across various species have not been rigorously examined. Here, we present comprehensive evolutionary analyses of the Aurora kinase family. Results Phylogenetic trees suggest that all three vertebrate Auroras evolved from a single urochordate ancestor. Specifically, Aurora-A is an orthologous lineage in cold-blooded vertebrates and mammals, while structurally similar Aurora-B and Aurora-C evolved more recently in mammals from a duplication of an ancestral Aurora-B/C gene found in cold-blooded vertebrates. All so-called Aurora-A and Aurora-B kinases of non-chordates are ancestral to the clade of chordate Auroras and, therefore, are not strictly orthologous to vertebrate counterparts. Comparisons of human Aurora-B and Aurora-C sequences to the resolved 3D structure of human Aurora-A lends further support to the evolutionary scenario that vertebrate Aurora-B and Aurora-C are closely related paralogs. Of the 26 residues lining the ATP-binding active site, only three were variant and all were specific to Aurora-A. Conclusions In

  16. Why Earth aurorae shine?

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ By using the data obtained from three satellites of the Cluster mission launched by the European Space Agency (ESA), CAO Jinbin from the CAS Center for Space Science and Applied Research (CSSAR) and his US and European co-workers have clarified why Earth's aurorae shine.Their work entitled Joint Observations by Cluster Satellites of Bursty Bulk Flows in the Magnetotail was published in a recent issue of Journal of Geophysical Research.

  17. Microtubules accelerate the kinase activity of Aurora-B by a reduction in dimensionality.

    Science.gov (United States)

    Noujaim, Michael; Bechstedt, Susanne; Wieczorek, Michal; Brouhard, Gary J

    2014-01-01

    Aurora-B is the kinase subunit of the Chromosome Passenger Complex (CPC), a key regulator of mitotic progression that corrects improper kinetochore attachments and establishes the spindle midzone. Recent work has demonstrated that the CPC is a microtubule-associated protein complex and that microtubules are able to activate the CPC by contributing to Aurora-B auto-phosphorylation in trans. Aurora-B activation is thought to occur when the local concentration of Aurora-B is high, as occurs when Aurora-B is enriched at centromeres. It is not clear, however, whether distributed binding to large structures such as microtubules would increase the local concentration of Aurora-B. Here we show that microtubules accelerate the kinase activity of Aurora-B by a "reduction in dimensionality." We find that microtubules increase the kinase activity of Aurora-B toward microtubule-associated substrates while reducing the phosphorylation levels of substrates not associated to microtubules. Using the single molecule assay for microtubule-associated proteins, we show that a minimal CPC construct binds to microtubules and diffuses in a one-dimensional (1D) random walk. The binding of Aurora-B to microtubules is salt-dependent and requires the C-terminal tails of tubulin, indicating that the interaction is electrostatic. We show that the rate of Aurora-B auto-activation is faster with increasing concentrations of microtubules. Finally, we demonstrate that microtubules lose their ability to stimulate Aurora-B when their C-terminal tails are removed by proteolysis. We propose a model in which microtubules act as scaffolds for the enzymatic activity of Aurora-B. The scaffolding activity of microtubules enables rapid Aurora-B activation and efficient phosphorylation of microtubule-associated substrates.

  18. Targeting the interaction of Aurora kinases and SIRT1 mediated by Wnt signaling pathway in colorectal cancer: A critical review.

    Science.gov (United States)

    Subramaniyan, Boopathi; Jagadeesan, Kaviya; Ramakrishnan, Sabitha; Mathan, Ganeshan

    2016-08-01

    The Aurora kinases belong to the family of serine/threonine kinase, a central regulator of mitosis and their expression increased during G2/M phase. It is classified into Aurora A, B and C, each has distinct roles in cellular processes, which includes regulation of spindle assembly, function of centrosomes, cytoskeleton and cytokinesis. During cancer growth, their rapid increase makes most attractive marker for cancer treatment at present. However Aurora A kinase is known to be a marker for cancer therapy, the most important serine/threonine kinase of Aurora B kinase involvement in cancer is still inadequate. Subsequently, the recent findings revealed that the class III histone deacetylase of SIRT1 is a key regulator to activate Aurora kinases from S phase damaged DNA through Wnt signaling pathway. Even if both Aurora A kinase and SIRT1 serve as a marker for cancer therapy, the present review reveals it is interaction in Wnt signaling pathway that solely for colorectal cancer.

  19. Aurorae in Australian Aboriginal Traditions

    CERN Document Server

    Hamacher, Duane W

    2013-01-01

    Transient celestial phenomena feature prominently in the astronomical knowledge and traditions of Aboriginal Australians. In this paper, I collect accounts of the Aurora Australis from the literature regarding Aboriginal culture. Using previous studies of meteors, eclipses, and comets in Aboriginal traditions, I anticipate that the physical properties of aurora, such as their generally red colour as seen from southern Australia, will be associated with fire, death, blood, and evil spirits. The survey reveals this to be the case and also explores historical auroral events in Aboriginal cultures, aurorae in rock art, and briefly compares Aboriginal auroral traditions with other global indigenous groups, including the Maori of New Zealand.

  20. Aurorae in Australian Aboriginal Traditions

    Science.gov (United States)

    Hamacher, Duane W.

    2013-07-01

    Transient celestial phenomena feature prominently in the astronomical knowledge and traditions of Aboriginal Australians. In this paper, I collect accounts of the Aurora Australis from the literature regarding Aboriginal culture. Using previous studies of meteors, eclipses, and comets in Aboriginal traditions, I anticipate that the physical properties of aurora, such as their generally red colour as seen from southern Australia, will be associated with fire, death, blood, and evil spirits. The survey reveals this to be the case and also explores historical auroral events in Aboriginal cultures, aurorae in rock art, and briefly compares Aboriginal auroral traditions with other global indigenous groups, including the Maori of New Zealand.

  1. The Aurora B kinase in chromosome biorientation and spindle checkpoint signalling

    Directory of Open Access Journals (Sweden)

    Veronica eKrenn

    2015-10-01

    Full Text Available Aurora B, a member of the Aurora family of serine/threonine protein kinases, is a key player in chromosome segregation. As part of a macromolecular complex known as the chromosome passenger complex, Aurora B concentrates early during mitosis in the proximity of centromeres and kinetochores, the sites of attachment of chromosomes to spindle microtubules. There, it contributes to a number of processes that impart fidelity to cell division, including kinetochore stabilization, kinetochore-microtubule attachment, and the regulation of a surveillance mechanism named the spindle assembly checkpoint. In the regulation of these processes, Aurora B is the fulcrum of a remarkably complex network of interactions that feed back on its localization and activation state. In this review we discuss the multiple roles of Aurora B during mitosis, focusing in particular on its role at centromeres and kinetochores. Many details of the network of interactions at these locations remain poorly understood, and we focus here on several crucial outstanding questions.

  2. HUBBLE PROVIDES COMPLETE VIEW OF JUPITER'S AURORAS

    Science.gov (United States)

    2002-01-01

    NASA's Hubble Space Telescope has captured a complete view of Jupiter's northern and southern auroras. Images taken in ultraviolet light by the Space Telescope Imaging Spectrograph (STIS) show both auroras, the oval- shaped objects in the inset photos. While the Hubble telescope has obtained images of Jupiter's northern and southern lights since 1990, the new STIS instrument is 10 times more sensitive than earlier cameras. This allows for short exposures, reducing the blurring of the image caused by Jupiter's rotation and providing two to five times higher resolution than earlier cameras. The resolution in these images is sufficient to show the 'curtain' of auroral light extending several hundred miles above Jupiter's limb (edge). Images of Earth's auroral curtains, taken from the space shuttle, have a similar appearance. Jupiter's auroral images are superimposed on a Wide Field and Planetary Camera 2 image of the entire planet. The auroras are brilliant curtains of light in Jupiter's upper atmosphere. Jovian auroral storms, like Earth's, develop when electrically charged particles trapped in the magnetic field surrounding the planet spiral inward at high energies toward the north and south magnetic poles. When these particles hit the upper atmosphere, they excite atoms and molecules there, causing them to glow (the same process acting in street lights). The electrons that strike Earth's atmosphere come from the sun, and the auroral lights remain concentrated above the night sky in response to the 'solar wind,' as Earth rotates underneath. Earth's auroras exhibit storms that extend to lower latitudes in response to solar activity, which can be easily seen from the northern U. S. But Jupiter's auroras are caused by particles spewed out by volcanoes on Io, one of Jupiter's moons. These charged particles are then magnetically trapped and begin to rotate with Jupiter, producing ovals of auroral light centered on Jupiter's magnetic poles in both the day and night skies

  3. The dawn of Aurora kinase research: from fly genetics to the clinic.

    Directory of Open Access Journals (Sweden)

    Mar eCarmena

    2015-11-01

    Full Text Available Aurora kinases comprise a family of highly conserved serine-threonine protein kinases that play a pivotal role in the regulation of cell cycle. Aurora kinases are not only involved in the control of multiple processes during cell division but also coordinate chromosomal and cytoskeletal events, contributing to the regulation of checkpoints and ensuring the smooth progression of the cell cycle.Because of their fundamental contribution to cell cycle regulation, Aurora kinases were originally identified in independent genetic screens designed to find genes involved in the regulation of cell division. The first aurora mutant was part of a collection of mutants isolated in C. Nusslein-Volhard’s laboratory. This collection was screened in D. M. Glover’s laboratory in search for mutations disrupting the centrosome cycle in embryos derived from homozygous mutant mothers. The mutants identified were given names related to the polar regions, and included not only aurora but also the equally famous polo. Ipl1, the only Aurora in yeast, was identified in a genetic screen looking for mutations that caused chromosome segregation defects. The discovery of a second Aurora-like kinase in mammals opened a new chapter in the research of Aurora kinases. The rat kinase AIM was found to be highly homologous to the fly and yeast proteins, but localised at the midzone and midbody and was proposed to have a role in cytokinesis. Homologs of the equatorial Aurora (Aurora B were identified in metazoans ranging from flies to humans. Xenopus Aurora B was found to be in a complex with the chromosomal passenger INCENP, and both proteins were shown to be essential in flies for chromosome structure, segregation, central spindle formation and cytokinesis. Fifteen years on, Aurora kinase research is an active field of research. After the successful introduction of the first anti-mitotic agents in cancer therapy, both Auroras have become the focus of attention as targets for

  4. Two TPX2-dependent switches control the activity of Aurora A.

    Directory of Open Access Journals (Sweden)

    Xue Xu

    Full Text Available Aurora A is an important oncogenic kinase for mitotic spindle assembly and a potentially attractive target for human cancers. Its activation could be regulated by ATP cycle and its activator TPX2. To understand the activation mechanism of Aurora A, a series of 20 ns molecular dynamics (MD simulations were performed on both the wild-type kinase and its mutants. Analyzing the three dynamic trajectories (Aurora A-ATP, Aurora A-ADP, and Aurora A-ADP-TPX2 at the residue level, for the first time we find two TPX2-dependent switches, i.e., switch-1 (Lys-143 and switch-2 (Arg-180, which are tightly associated with Aurora A activation. In the absence of TPX2, Lys-143 exhibits a "closed" state, and becomes hydrogen-bonded to ADP. Once TPX2 binding occurs, switch-1 is forced to "open" the binding site, thus pulling ADP away from Aurora A. Without facilitation of TPX2, switch-2 exits in an "open" conformation which accompanies the outward-flipping movement of P·Thr288 (in an inactive conformation, leading to the crucial phosphothreonine exposed and accessible for deactivation. However, with the binding of TPX2, switch-2 is forced to undergo a "closed" movement, thus capturing P·Thr288 into a buried position and locking its active conformation. Analysis of two Aurora A (K143A and R180A mutants for the two switches further verifies their functionality and reliability in controlling Aurora activity. Our systems therefore suggest two switches determining Aurora A activation, which are important for the development of aurora kinase inhibitors.

  5. Update on Aurora Kinase Targeted Therapeutics in Oncology

    Science.gov (United States)

    Green, Myke R.; Woolery, Joseph E.

    2011-01-01

    Introduction Mammalian cells contain three distinct serine/threonine protein kinases with highly conserved catalytic domains, including aurora A and B kinases that are essential regulators of mitotic entry and progression. Overexpression of aurora A and/or B kinase is associated with high proliferation rates and poor prognosis, making them ideal targets for anti-cancer therapy. Disruption of mitotic machinery is a proven anti-cancer strategy employed by multiple chemotherapeutic agents. Numerous small molecule inhibitors of the aurora kinases have been discovered and tested in vivo and in vitro, with a few currently in phase II testing. Areas covered This review provides the reader with updated results from both preclinical and human studies for each of the aurora kinase inhibitors (AKI) that are currently being investigated. The paper also covers in detail the late breaking and phase I data presented for AKIs thereby allowing the reader to compare and contrast individual and classrelated effects of AKIs. Expert opinion While the successful development and approval of an AKI for anti-cancer therapy remains unresolved, pre-clinical identification of resistant mechanisms would help design better early phase clinical trials where relevant combinations may be evaluated prior to phase II testing. The authors believe that aurora kinases are important anti-cancer targets that operate in collaboration with other oncogenes intimately involved in uncontrolled tumor proliferation and by providing a unique, targeted and complimentary anti-cancer mechanism, expand the available armamentarium against cancer. PMID:21556291

  6. Identification of Ski as a target for Aurora A kinase.

    Science.gov (United States)

    Mosquera, Jocelyn; Armisen, Ricardo; Zhao, Hongling; Rojas, Diego A; Maldonado, Edio; Tapia, Julio C; Colombo, Alicia; Hayman, Michael J; Marcelain, Katherine

    2011-06-10

    Ski is a negative regulator of the transforming growth factor-β and other signalling pathways. The absence of SKI in mouse fibroblasts leads to chromosome segregation defects and genomic instability, suggesting a role for Ski during mitosis. At this stage, Ski is phosphorylated but to date little is known about the kinases involved in this process. Here, we show that Aurora A kinase is able to phosphorylate Ski in vitro. In vivo, Aurora A and Ski co-localized at the centrosomes and co-immunoprecipitated. Conversely, a C-terminal truncation mutant of Ski (SkiΔ491-728) lacking a coiled-coil domain, displayed decreased centrosomal localization. This mutant no longer co-immunoprecipitated with Aurora-A in vivo, but was still phosphorylated in vitro, indicating that the Ski-Aurora A interaction takes place at the centrosomes. These data identify Ski as a novel target of Aurora A and contribute to an understanding of the role of these proteins in the mitotic process.

  7. Localized Aurora B activity spatially controls non-kinetochore microtubules during spindle assembly.

    Science.gov (United States)

    Tanenbaum, Marvin E; Medema, René H

    2011-12-01

    Efficient spindle assembly involves the generation of spatial cues around chromosomes that locally stabilize microtubule (MT) plus-ends. In addition to the small GTPase Ran, there is evidence that Aurora B kinase might also generate a spatial cue around chromosomes but direct proof for this is still lacking. Here, we find that the Aurora B substrate MCAK localizes to MT plus-ends throughout the mitotic spindle, but its accumulation is strongly reduced on MT plus-ends near chromatin, suggesting that a signal emanating from chromosomes negatively regulates MCAK plus-end binding. Indeed, we show that Aurora B is the kinase responsible for producing this chromosome-derived signal. These results are the first to visualize spatially restricted Aurora B kinase activity around chromosomes on an endogenous substrate and explain how Aurora B could spatially control the dynamics of non-kinetochore MTs during spindle assembly.

  8. Therapeutic potential of mitotic interaction between the nucleoporin Tpr and aurora kinase A.

    Science.gov (United States)

    Kobayashi, Akiko; Hashizume, Chieko; Dowaki, Takayuki; Wong, Richard W

    2015-01-01

    Spindle poles are defined by centrosomes; therefore, an abnormal number or defective structural organization of centrosomes can lead to loss of spindle bipolarity and genetic integrity. Previously, we showed that Tpr (translocated promoter region), a component of the nuclear pore complex (NPC), interacts with Mad1 and dynein to promote proper chromosome segregation during mitosis. Tpr also associates with p53 to induce autophagy. Here, we report that Tpr depletion induces mitotic catastrophe and enhances the rate of tetraploidy and polyploidy. Mechanistically, Tpr interacts, via its central domain, with Aurora A but not Aurora B kinase. In Tpr-depleted cells, the expression levels, centrosomal localization and phosphorylation of Aurora A were all reduced. Surprisingly, an Aurora A inhibitor, Alisertib (MLN8237), also disrupted centrosomal localization of Tpr and induced mitotic catastrophe and cell death in a time- and dose-dependent manner. Strikingly, over-expression of Aurora A disrupted Tpr centrosomal localization only in cells with supernumerary centrosomes but not in bipolar cells. Our results highlight the mutual regulation between Tpr and Aurora A and further confirm the importance of nucleoporin function in spindle pole organization, bipolar spindle assembly, and mitosis; functions that are beyond the conventional nucleocytoplasmic transport and NPC structural roles of nucleoporins. Furthermore, the central coiled-coil domain of Tpr binds to and sequesters extra Aurora A to safeguard bipolarity. This Tpr domain merits further investigation for its ability to inhibit Aurora kinase and as a potential therapeutic agent in cancer treatment.

  9. Aurorae and Volcanic Eruptions

    Science.gov (United States)

    2001-06-01

    Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A volcanic eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of volcanic activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its volcanic moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere

  10. p53 deficiency enhances mitotic arrest and slippage induced by pharmacological inhibition of Aurora kinases.

    Science.gov (United States)

    Marxer, M; Ma, H T; Man, W Y; Poon, R Y C

    2014-07-01

    A number of small-molecule inhibitors of Aurora kinases have been developed and are undergoing clinical trials for anti-cancer therapies. Different Aurora kinases, however, behave as very different targets: while inhibition of Aurora A (AURKA) induces a delay in mitotic exit, inhibition of Aurora B (AURKB) triggers mitotic slippage. Furthermore, while it is evident that p53 is regulated by Aurora kinase-dependent phosphorylation, how p53 may in turn regulate Aurora kinases remains mysterious. To address these issues, isogenic p53-containing and -negative cells were exposed to classic inhibitors that target both AURKA and AURKB (Alisertib and ZM447439), as well as to new generation of inhibitors that target AURKA (MK-5108), AURKB (Barasertib) individually. The fate of individual cells was then tracked with time-lapse microscopy. Remarkably, loss of p53, either by gene disruption or small interfering RNA-mediated depletion, sensitized cells to inhibition of both AURKA and AURKB, promoting mitotic arrest and slippage respectively. As the p53-dependent post-mitotic checkpoint is also important for preventing genome reduplication after mitotic slippage, these studies indicate that the loss of p53 in cancer cells represents a major opportunity for anti-cancer drugs targeting the Aurora kinases.

  11. Indomethacin promotes apoptosis in gastric cancer cells through concomitant degradation of Survivin and Aurora B kinase proteins.

    Science.gov (United States)

    Chiou, Shiun-Kwei; Hoa, Neil; Hodges, Amy; Ge, Lishen; Jadus, Martin R

    2014-09-01

    Regular usage of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with reduced incidence of a variety of cancers. The molecular mechanisms underlying these chemopreventive effects remain poorly understood. This current investigation showed that in gastric cancer cells: (1) Indomethacin treatment enhanced the degradation of chromosomal passenger proteins, Survivin and Aurora B kinase; (2) Indomethacin treatment down-regulated Aurora B kinase activity in a cell cycle-independent fashion; (3) siRNA knockdown of Survivin level promoted Aurora B kinase protein degradation, and vice versa; (4) ectopic overexpression of Survivin blocked reduction of Aurora B kinase level and activity by indomethacin treatment, and vice versa; (5) siRNA knockdown of Aurora B kinase level and AZD1152 inhibition of its activity induced apoptosis, and overexpression of Aurora B kinase inhibited indomethacin-induced apoptosis; (6) indomethacin treatment reduced Aurora B kinase level, coinciding with reduction of Survivin level and induction of apoptosis, in KATO III and HT-29 cells, and in mouse gastric mucosa. A role for Aurora B kinase function in NSAID-induced apoptosis was not previously explored. Thus this report provides better understanding of the molecular mechanisms underlying the anti-cancer effect of NSAIDs by elucidating a significant role for Aurora B kinase in indomethacin-induced apoptosis.

  12. EBNA3C-mediated regulation of aurora kinase B contributes to Epstein-Barr virus-induced B-cell proliferation through modulation of the activities of the retinoblastoma protein and apoptotic caspases.

    Science.gov (United States)

    Jha, Hem Chandra; Lu, Jie; Saha, Abhik; Cai, Qiliang; Banerjee, Shuvomoy; Prasad, Mahadesh A J; Robertson, Erle S

    2013-11-01

    Epstein-Barr virus (EBV) is an oncogenic gammaherpesvirus that is implicated in several human malignancies, including Burkitt's lymphoma (BL), posttransplant lymphoproliferative disease (PTLD), nasopharyngeal carcinoma (NPC), and AIDS-associated lymphomas. Epstein-Barr nuclear antigen 3C (EBNA3C), one of the essential EBV latent antigens, can induce mammalian cell cycle progression through its interaction with cell cycle regulators. Aurora kinase B (AK-B) is important for cell division, and deregulation of AK-B is associated with aneuploidy, incomplete mitotic exit, and cell death. Our present study shows that EBNA3C contributes to upregulation of AK-B transcript levels by enhancing the activity of its promoter. Further, EBNA3C also increased the stability of the AK-B protein, and the presence of EBNA3C leads to reduced ubiquitination of AK-B. Importantly, EBNA3C in association with wild-type AK-B but not with its kinase-dead mutant led to enhanced cell proliferation, and AK-B knockdown can induce nuclear blebbing and cell death. This phenomenon was rescued in the presence of EBNA3C. Knockdown of AK-B resulted in activation of caspase 3 and caspase 9, along with poly(ADP-ribose) polymerase 1 (PARP1) cleavage, which is known to be an important contributor to apoptotic signaling. Importantly, EBNA3C failed to stabilize the kinase-dead mutant of AK-B compared to wild-type AK-B, which suggests a role for the kinase domain in AK-B stabilization and downstream phosphorylation of the cell cycle regulator retinoblastoma protein (Rb). This study demonstrates the functional relevance of AK-B kinase activity in EBNA3C-regulated B-cell proliferation and apoptosis.

  13. Arsenic-induced Aurora-A activation contributes to chromosome instability and tumorigenesis

    Science.gov (United States)

    Wu, Chin-Han; Tseng, Ya-Shih; Yang, Chao-Chun; Kao, Yu-Ting; Sheu, Hamm-Ming; Liu, Hsiao-Sheng

    2013-11-01

    Arsenic may cause serious environmental pollution and is a serious industrial problem. Depending on the dosage, arsenic may trigger the cells undergoing either proliferation or apoptosis-related cell death. Because of lack of the proper animal model to study arsenic induced tumorigenesis, the accurate risk level of arsenic exposure has not been determined. Arsenic shows genotoxic effect on human beings who uptake water contaminated by arsenic. Chromosome aberration is frequently detected in arsenic exposure-related diseases and is associated with increased oxidative stress and decreased DNA repairing activity, but the underlying mechanism remains elusive. Aurora-A is a mitotic kinase, over-expression of Aurora-A leads to centrosome amplification, chromosomal instability and cell transformation. We revealed that Aurora-A is over-expressed in the skin and bladder cancer patients from blackfoot-disease endemic areas. Our cell line studies reveal that arsenic exposure between 0.5 μM and 1 μM for 2-7 days are able to induce Aurora-A expression and activation based on promoter activity, RNA and protein analysis. Aurora-A overexpression further increases the frequency of unsymmetrical chromosome segregation through centrosome amplification followed by cell population accumulated at S phase in immortalized keratinocyte (HaCaT) and uroepithelial cells (E7). Furthermore, Aurora-A over-expression was sustained for 1-4 weeks by chronic treatment of immortalized bladder and skin cells with NaAsO2. Aurora-A promoter methylation and gene amplification was not detected in the long-term arsenic treated E7 cells. Furthermore, the expression level of E2F1 transcription factor (E2F1) is increased in the presence of arsenic, and arsenic-related Aurora-A over-expression is transcriptionally regulated by E2F1. We further demonstrated that overexpression of Aurora-A and mutant Ha-ras or Aurora-A and mutant p53 may act additively to trigger arsenic-related bladder and skin cancer

  14. Aurora B prevents chromosome arm separation defects by promoting telomere dispersion and disjunction

    OpenAIRE

    Reyes, Céline; Serrurier, Céline; Gauthier, Tiphaine; Gachet, Yannick; Tournier, Sylvie

    2015-01-01

    The segregation of centromeres and telomeres at mitosis is coordinated at multiple levels to prevent the formation of aneuploid cells, a phenotype frequently observed in cancer. Mitotic instability arises from chromosome segregation defects, giving rise to chromatin bridges at anaphase. Most of these defects are corrected before anaphase onset by a mechanism involving Aurora B kinase, a key regulator of mitosis in a wide range of organisms. Here, we describe a new role for Aurora B in telomer...

  15. Significance of Aurora B overexpression in hepatocellular carcinoma. Aurora B Overexpression in HCC

    Directory of Open Access Journals (Sweden)

    Lin Zhong-Zhe

    2010-08-01

    Full Text Available Abstract Background To investigate the significance of Aurora B expression in hepatocellular carcinoma (HCC. Methods The Aurora B and Aurora A mRNA level was measured in 160 HCCs and the paired nontumorous liver tissues by reverse transcription-polymerase chain reaction. Mutations of the p53 and β-catenin genes were analyzed in 134 and 150 tumors, respectively, by direct sequencing of exon 2 to exon 11 of p53 and exon 3 of β-catenin. Anticancer effects of AZD1152-HQPA, an Aurora B kinase selective inhibitor, were examined in Huh-7 and Hep3B cell lines. Results Aurora B was overexpressed in 98 (61% of 160 HCCs and in all 7 HCC cell lines examined. The overexpression of Aurora B was associated with Aurora A overexpression (P = 0.0003 and p53 mutation (P = 0.002 and was inversely associated with β-catenin mutation (P = 0.002. Aurora B overexpression correlated with worse clinicopathologic characteristics. Multivariate analysis confirmed that Aurora B overexpression was an independent poor prognostic factor, despite its interaction with Aurora A overexpression and mutations of p53 and β-catenin. In Huh-7 and Hep3B cells, AZD1152-HQPA induced proliferation blockade, histone H3 (Ser10 dephosphorylation, cell cycle disturbance, and apoptosis. Conclusion Aurora B overexpression is an independent molecular marker predicting tumor invasiveness and poor prognosis of HCC. Aurora B kinase selective inhibitors are potential therapeutic agents for HCC treatment.

  16. Aurora A kinase activates YAP signaling in triple-negative breast cancer.

    Science.gov (United States)

    Chang, S-S; Yamaguchi, H; Xia, W; Lim, S-O; Khotskaya, Y; Wu, Y; Chang, W-C; Liu, Q; Hung, M-C

    2017-03-02

    The Yes-associated protein (YAP) is an effector that transduces the output of the Hippo pathway to transcriptional modulation. Considering the role of YAP in cancers, this protein has emerged as a key node in malignancy development. In this study, we determined that Aurora A kinase acts as a positive regulator for YAP-mediated transcriptional machinery. Specifically, YAP associates with Aurora A predominantly in the nucleus. Activation of Aurora A can impinge on YAP activity through direct phosphorylation. Moreover, aberrant expression of YAP and Aurora A signaling is highly correlated with triple-negative breast cancer (TNBC). We herein provide evidence to establish the functional relevance of this newly discovered regulatory axis in TNBC.

  17. Aurora A phosphorylates MCAK to control ran-dependent spindle bipolarity.

    Science.gov (United States)

    Zhang, Xin; Ems-McClung, Stephanie C; Walczak, Claire E

    2008-07-01

    During mitosis, mitotic centromere-associated kinesin (MCAK) localizes to chromatin/kinetochores, a cytoplasmic pool, and spindle poles. Its localization and activity in the chromatin region are regulated by Aurora B kinase; however, how the cytoplasmic- and pole-localized MCAK are regulated is currently not clear. In this study, we used Xenopus egg extracts to form spindles in the absence of chromatin and centrosomes and found that MCAK localization and activity are tightly regulated by Aurora A. This regulation is important to focus microtubules at aster centers and to facilitate the transition from asters to bipolar spindles. In particular, we found that MCAK colocalized with NuMA and XMAP215 at the center of Ran asters where its activity is regulated by Aurora A-dependent phosphorylation of S196, which contributes to proper pole focusing. In addition, we found that MCAK localization at spindle poles was regulated through another Aurora A phosphorylation site (S719), which positively enhances bipolar spindle formation. This is the first study that clearly defines a role for MCAK at the spindle poles as well as identifies another key Aurora A substrate that contributes to spindle bipolarity.

  18. Aurora europe's space exploration programme

    Science.gov (United States)

    Ongaro, F.; Swings, J. P.; Condessa, R.

    2003-04-01

    What will happen after the ISS in terms of space exploration, specifically to the human presence beyond Earth? What will be the role of Europe in the future international venture to explore space? What are the most immediate actions to be undertaken in Europe in order to best profit from the efforts made through the participation in the ISS and to position Europe's capabilities according to its interests? As approved by the Ministers at the Edinburgh Council in November 2001, the European Space Exploration Programme - Aurora - is ESA's programme in charge of defining and implementing the long term plan for human and robotic exploration of the Solar system. The Aurora programme started in 2002 and extends until the end goal of Aurora: the first human mission to Mars, expected in the 2025-2030 time-frame. The approach of Aurora is to implement a robust development of technologies and robotic missions, in parallel to the utilization phase of the ISS, to prepare for a continuous and sustainable future of human space exploration (which shall include the Moon, Mars and the asteroids as targets), in which Europe will be a valuable partner. Two classes of missions are foreseen in the programme's strategy: Flagships, defined as major missions driving to soft landing, in-situ analysis, sample return from other planetary bodies and eventually human missions; and Arrows, defined as cost-capped, short development time missions to demonstrate new technologies or mission approaches, or to exploit opportunities for payloads on European or international missions. So far the participating national delegations have approved two Flagships (ExoMars and Mars Sample Return) and two Arrows (Earth Re-entry and Mars Aerocapture) for phase A industrial studies. Although the last call for ideas of Aurora resulted in the definition of two Flagship missions targeted to Mars, the next one might be aimed to the Moon. At this stage the role of the Moon, on the path of Mars exploration is not

  19. Electron assisted glow discharges for conditioning fusion tokamak devices

    Science.gov (United States)

    Schaubel, K. M.; Jackson, G. L.

    1989-08-01

    Glow discharge conditioning of tokamaks with graphite plasma-facing surfaces has been used to reduce impurities and obtain density control of the plasma discharge. However, a major operational disadvantage of glow conditioning is the high pressure required to initiate the glow discharge, e.g., approx. 70 mTorr for helium in DIII-D, which requires isolating auxiliary components that can not tolerate the high pressure. An electron-gun assisted glow discharge can lower breakdown pressure, possibly eliminating the necessity of isolating these auxiliary systems during glow discharge conditioning and allowing glow discharge operation at lower pressures.

  20. Nature's Fireworks: The Inner Workings of the Auroras.

    Science.gov (United States)

    Kikoyin, A. K.

    1992-01-01

    Describes the great variety of observations surrounding the auroras (both borealis and australis), and provides photographs from the space shuttle, Discovery. Discusses where and when the auroras can be observed, the process that the Earth's magnetic phenomena fulfill in how and why auroras appear, and the effects of solar wind upon auroras. (JJK)

  1. The Glowing Pickle and Other Vegetables

    Directory of Open Access Journals (Sweden)

    Ryan Burns

    2009-06-01

    Full Text Available The phenomenon known as the glowing pickle was investigated. Voltages ranging from 80-140 Volts AC were placed across a variety of vegetable specimens, both fresh and soaked in several salt solutions. The glowing was caused by electric arcing across a steam-filled cavity in the specimen. The emission spectra showed lines indicating the presence of potassium and sodium ions in the fresh specimens. In the specimens soaked in salt solutions, emission spectra matching the salt ions were observed.

  2. Glow and pseudo-glow discharges in a surface discharge generator

    Institute of Scientific and Technical Information of China (English)

    Li Xue-Chen; Dong Li-Fang; Wang Long

    2005-01-01

    The glow discharge in flowing argon at one atmospheric pressure is realized in a surface discharge generator. The discharge current presents one peak per half-cycle of the applied voltage. The duration of the discharge pulse is more than 1μs when the frequency of the applied voltage is 60kHz. For the glow discharge in argon, the power consumption increases with the increase of voltage or the decrease of gas pressure.This relation is explained qualitatively based on the theory of the Townsend breakdown mechanism. In contrast, the discharge current in one atmospheric pressure air gives many spikes in each half-cycle, and correspondingly this kind of discharge is called pseudo-glow discharge. Every current spike oscillates with high-frequency damping. The pseudo-glow discharge in one atmospheric pressure air might result from the streamer breakdown mechanism.

  3. Aurora B suppresses microtubule dynamics and limits central spindle size by locally activating KIF4A

    Science.gov (United States)

    Nunes Bastos, Ricardo; Gandhi, Sapan R.; Baron, Ryan D.; Gruneberg, Ulrike; Nigg, Erich A.

    2013-01-01

    Anaphase central spindle formation is controlled by the microtubule-stabilizing factor PRC1 and the kinesin KIF4A. We show that an MKlp2-dependent pool of Aurora B at the central spindle, rather than global Aurora B activity, regulates KIF4A accumulation at the central spindle. KIF4A phosphorylation by Aurora B stimulates the maximal microtubule-dependent ATPase activity of KIF4A and promotes its interaction with PRC1. In the presence of phosphorylated KIF4A, microtubules grew more slowly and showed long pauses in growth, resulting in the generation of shorter PRC1-stabilized microtubule overlaps in vitro. Cells expressing only mutant forms of KIF4A lacking the Aurora B phosphorylation site overextended the anaphase central spindle, demonstrating that this regulation is crucial for microtubule length control in vivo. Aurora B therefore ensures that suppression of microtubule dynamic instability by KIF4A is restricted to a specific subset of microtubules and thereby contributes to central spindle size control in anaphase. PMID:23940115

  4. Antineoplastic effects of an Aurora B kinase inhibitor in breast cancer

    Directory of Open Access Journals (Sweden)

    Velazquez-Torres Guermarie

    2010-02-01

    Full Text Available Abstract Background Aurora B kinase is an important mitotic kinase involved in chromosome segregation and cytokinesis. It is overexpressed in many cancers and thus may be an important molecular target for chemotherapy. AZD1152 is the prodrug for AZD1152-HQPA, which is a selective inhibitor of Aurora B kinase activity. Preclinical antineoplastic activity of AZD1152 against acute myelogenous leukemia, multiple myeloma and colorectal cancer has been reported. However, this compound has not been evaluated in breast cancer, the second leading cause of cancer deaths among women. Results The antineoplastic activity of AZD1152-HQPA in six human breast cancer cell lines, three of which overexpress HER2, is demonstrated. AZD1152-HQPA specifically inhibited Aurora B kinase activity in breast cancer cells, thereby causing mitotic catastrophe, polyploidy and apoptosis, which in turn led to apoptotic death. AZD1152 administration efficiently suppressed the tumor growth in a breast cancer cell xenograft model. In addition, AZD1152 also inhibited pulmonary metastatic nodule formation in a metastatic breast cancer model. Notably, it was also found that the protein level of Aurora B kinase declined after inhibition of Aurora B kinase activity by AZD1152-HQPA in a time- and dose-dependent manner. Investigation of the underlying mechanism suggested that AZD1152-HQPA accelerated protein turnover of Aurora B via enhancing its ubiquitination. Conclusions It was shown that AZD1152 is an effective antineoplastic agent for breast cancer, and our results define a novel mechanism for posttranscriptional regulation of Aurora B after AZD1152 treatment and provide insight into dosing regimen design for this kinase inhibitor in metastatic breast cancer treatment.

  5. Low Latitude Aurora: Index of Solar Activity

    Science.gov (United States)

    Bekli, M. R.; Aissani, D.; Chadou, I.

    2010-10-01

    Observations of aurora borealis at low latitudes are rare, and are clearly associated with high solar activity. In this paper, we analyze some details of the solar activity during the years 1769-1792. Moreover, we describe in detail three low latitude auroras. The first event was reported by ash-Shalati and observed in North Africa (1770 AD). The second and third events were reported by l'Abbé Mann and observed in Europe (1770 and 1777 AD).

  6. Aurora-A Oncogene in Human Ovarian Cancer

    Science.gov (United States)

    2006-11-01

    in Human Ovarian Cancer 5b. GRANT NUMBER W81XWH-05-1-0021 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Jin Q. Cheng, M.D...this project : 1) examine the clinicalpathological significance and the mechanism of Aurora-A overexpression/activation in ovarian cancer; 2) determine...kinase is required to localize D-TACC to centro- somes and to regulate astral microtubules. J Cell Biol 2002;156:437–51. 33. Castro A, Mandart E, Lorca T

  7. Aurora B kinase and protein phosphatase 1 have opposing roles in modulating kinetochore assembly.

    Science.gov (United States)

    Emanuele, Michael J; Lan, Weijie; Jwa, Miri; Miller, Stephanie A; Chan, Clarence S M; Stukenberg, P Todd

    2008-04-21

    The outer kinetochore binds microtubules to control chromosome movement. Outer kinetochore assembly is restricted to mitosis, whereas the inner kinetochore remains tethered to centromeres throughout the cell cycle. The cues that regulate this transient assembly are unknown. We find that inhibition of Aurora B kinase significantly reduces outer kinetochore assembly in Xenopus laevis and human tissue culture cells, frog egg extracts, and budding yeast. In X. leavis M phase extracts, preassembled kinetochores disassemble after inhibiting Aurora B activity with either drugs or antibodies. Kinetochore disassembly, induced by Aurora B inhibition, is rescued by restraining protein phosphatase 1 (PP1) activity. PP1 is necessary for kinetochores to disassemble at the exit from M phase, and purified enzyme is sufficient to cause disassembly on isolated mitotic nuclei. These data demonstrate that Aurora B activity is required for kinetochore maintenance and that PP1 is necessary and sufficient to disassemble kinetochores. We suggest that Aurora B and PP1 coordinate cell cycle-dependent changes in kinetochore assembly though phosphorylation of kinetochore substrates.

  8. Combined cisplatin and aurora inhibitor treatment increase neuroblastoma cell death but surviving cells overproduce BDNF.

    Science.gov (United States)

    Polacchini, Alessio; Albani, Clara; Baj, Gabriele; Colliva, Andrea; Carpinelli, Patrizia; Tongiorgi, Enrico

    2016-07-15

    Drug-resistance to chemotherapics in aggressive neuroblastoma (NB) is characterized by enhanced cell survival mediated by TrkB and its ligand, brain-derived neurotrophic factor (BDNF); thus reduction in BDNF levels represent a promising strategy to overcome drug-resistance, but how chemotherapics regulate BDNF is unknown. Here, cisplatin treatment in SK-N-BE neuroblastoma upregulated multiple BDNF transcripts, except exons 5 and 8 variants. Cisplatin increased BDNF mRNA and protein, and enhanced translation of a firefly reporter gene flanked by BDNF 5'UTR exons 1, 2c, 4 or 6 and 3'UTR-long. To block BDNF translation we focused on aurora kinases inhibitors which are proposed as new chemotherapeutics. NB cell survival after 24 h treatment was 43% with cisplatin, and 22% by cisplatin+aurora kinase inhibitor PHA-680632, while the aurora kinases inhibitor alone was less effective; however the combined treatment induced a paradoxical increase of BDNF in surviving cells with strong translational activation of exon6-3'UTR-long transcript, while translation of BDNF transcripts 1, 2C and 4 was suppressed. In conclusion, combined cisplatin and aurora kinase inhibitor treatment increases cell death, but induces BDNF overproduction in surviving cells through an aurora kinase-independent mechanism.

  9. Statistical study of dayside pulsating aurora

    Science.gov (United States)

    Kanmae, T.; Kadokura, A.; Ogawa, Y.; Ebihara, Y.; Motoba, T.; Gerrard, A. J.; Weatherwax, A. T.

    2015-12-01

    Pulsating aurora normally occurs after a substorm breakup in the midnight sector, often observed to persist through the morning sector and beyond. Indeed, it has also been observed on the dayside; however, the characteristics of the dayside pulsating aurora are poorly known. A handful of observational studies have been reported, but the results are somewhat disputable because most of the studies had non-uniform sampling of the dark dayside region. Furthermore, the previous studies used photometer data, with which the spatial characteristics of the pulsating aurora cannot be examined. To determine both temporal and spatial characteristics of the pulsating aurora, we have studied three years of all-sky image data obtained at the South Pole station. Because of its unique geographical location, the station has 24 hours of darkness during the austral winter from April to August, providing an ideal platform for studying dayside aurora. In a preliminary survey of the data, we have identified the pulsating auroras in 198 days out of 365 days of observations. The magnetic local time (MLT) distribution of the occurrence peaks between 9:00 and 11:00, but shows no or little dependence on the geomagnetic activity. In many events, pulsating patches initially appear as east-west aligned arc segments and later in the afternoon sector develop into large, diffuse patches, which occasionally fill a large part of the field of view. Using the long-term data, we will statistically examine both temporal (occurrence rate, duration and pulsation period) and spatial (sizes and shapes) characteristics of the dayside pulsating aurora.

  10. Recognizing blue emission in artificial aurora

    Science.gov (United States)

    Holma, H.; Kaila, K.; Jussila, J.; Kosch, M.; Rietveld, M.

    On 12th November 2001, during the EISCAT UK/GE artificial aurora campaign, the optical group of University of Oulu performed the optical measurements at the EISCAT site in Ramfjordmoen. That campaign was the first successful attempt of inducing blue emission in artificial aurora at high latitudes. Optical instruments were monitoring emis-sions and they included a photometer, a real speed TV camera and a digital camera. The emissions measured by the photometer are 557.7 nm (OI), 630.0 nm (OI) and 427.8 nm (N2+). The threshold energies for these emissions to arise are 2 eV, 4 eV and 19 eV, re-spectively. In the natural aurora the blue emission at around 427 nm is always highly dominated by N2+ 1NG (0,1) rotational band. However, there are two weak emissions lying under this strong emission. These bands are N2 VK(4,15) (threshold energy 6 eV) and N2 2P(1,5) (threshold 11 eV). These energies are remarkably lower and could obviously have stronger intensity in the spectrum of artificial aurora than in natural aurora that is domi-nated by harder electron bombardment. The auroral photometer of the university of Oulu has been designed for investigating natural aurora, which results some limitations regarding the artificial aurora, to the data that has been obtained. The photometer was equipped with two channels measuring two close wavelength bands around 427 nm. These channels were aimed to be used to de-termine rotational temperature from the ratio of the intensities through the channels. Now they will be used to estimate the intensities of the three overlapping emission bands instead.

  11. Atmospheric physics: Chorus keeps the diffuse aurora humming

    Science.gov (United States)

    Newell, Patrick T.

    2010-10-01

    The origin of the diffuse aurora, whose beauty and intensity pale beside those of the famous aurora borealis, has remained controversial. A convincing explanation for this auroral display is now at hand. See Letter p.943

  12. Evaluation of the Aurora Application Shade Measurement Accuracy

    Energy Technology Data Exchange (ETDEWEB)

    2015-12-01

    Aurora is an integrated, Web-based application that helps solar installers perform sales, engineering design, and financial analysis. One of Aurora's key features is its high-resolution remote shading analysis.

  13. Induction of p21CIP1 protein and cell cycle arrest after inhibition of Aurora B kinase is attributed to aneuploidy and reactive oxygen species.

    Science.gov (United States)

    Kumari, Geeta; Ulrich, Tanja; Krause, Michael; Finkernagel, Florian; Gaubatz, Stefan

    2014-06-01

    Cell cycle progression requires a series of highly coordinated events that ultimately lead to faithful segregation of chromosomes. Aurora B is an essential mitotic kinase, which is involved in regulation of microtubule-kinetochore attachments and cytokinesis. Inhibition of Aurora B results in stabilization of p53 and induction of p53-target genes such as p21 to inhibit proliferation. We have previously demonstrated that induction of p21 by p53 after inhibition of Aurora B is dependent on the p38 MAPK, which promotes transcriptional elongation of p21 by RNA Pol II. In this study, we show that a subset of p53-target genes are induced in a p38-dependent manner upon inhibition of Aurora B. We also demonstrate that inhibition of Aurora B results in down-regulation of E2F-mediated transcription and that the cell cycle arrest after Aurora B inhibition depends on p53 and pRB tumor suppressor pathways. In addition, we report that activation of p21 after inhibition of Aurora B is correlated with increased chromosome missegregation and aneuploidy but not with binucleation or tetraploidy. We provide evidence that p21 is activated in aneuploid cells by reactive oxygen species (ROS) and p38 MAPK. Finally, we demonstrate that certain drugs that act on aneuploid cells synergize with inhibitors of Aurora B to inhibit colony formation and oncogenic transformation. These findings provide an important link between aneuploidy and the stress pathways activated by Aurora B inhibition and also support the use of Aurora B inhibitors in combination therapy for treatment of cancer.

  14. Discrete auroras and magnetotail processes.

    Science.gov (United States)

    Lyons, L. R.

    Important information about magnetospheric phenomena associated with auroras and substorms can be inferred from low-altitude auroral observations. Satellite observations have shown that discrete auroral arcs lie within a boundary plasma sheet (BPS) region that is outside the central plasma sheet (CPS). The observations imply that arcs are generated along BPS field lines by magnetospheric processes that form large, perpendicular electric field structures. The BPS and the arc generation processes apparently lie along field lines that are in the vicinity of the boundary between open and closed field lines and cross the tail (or magnetopause) current sheet. Ground-based observations show that the first indication of a substorm onset is the brightening of a quiet, discrete arc. This suggests that substorms are initiated along the BPS field lines associated with arc generation, and not within the CPS. Finally, auroral observations have shown that the area of open, polar-cap field lines varies considerably during periods of geomagnetic activity. Expansion of the polar cap has the potential for releasing trapped plasma sheet particles along freshly open field lines. The resulting evacuation of field lines has the potential for being an important loss process for the plasma sheet and for being a source of tailward flows and energetic particle bursts in the tail.

  15. Discovery of diffuse aurora on Mars.

    Science.gov (United States)

    Schneider, N M; Deighan, J I; Jain, S K; Stiepen, A; Stewart, A I F; Larson, D; Mitchell, D L; Mazelle, C; Lee, C O; Lillis, R J; Evans, J S; Brain, D; Stevens, M H; McClintock, W E; Chaffin, M S; Crismani, M; Holsclaw, G M; Lefevre, F; Lo, D Y; Clarke, J T; Montmessin, F; Jakosky, B M

    2015-11-01

    Planetary auroras reveal the complex interplay between an atmosphere and the surrounding plasma environment. We report the discovery of low-altitude, diffuse auroras spanning much of Mars' northern hemisphere, coincident with a solar energetic particle outburst. The Imaging Ultraviolet Spectrograph, a remote sensing instrument on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, detected auroral emission in virtually all nightside observations for ~5 days, spanning nearly all geographic longitudes. Emission extended down to ~60 kilometer (km) altitude (1 microbar), deeper than confirmed at any other planet. Solar energetic particles were observed up to 200 kilo--electron volts; these particles are capable of penetrating down to the 60 km altitude. Given minimal magnetic fields over most of the planet, Mars is likely to exhibit auroras more globally than Earth.

  16. Possible Role of Aurora-C in Meiosis

    Directory of Open Access Journals (Sweden)

    Kuo-Tai eYang

    2015-08-01

    Full Text Available The meiotic generation of haploid gametes with equal contents of genetic material is important for sexual reproduction in mammals. Errors in the transmission of chromosomes during meiosis may lead to aneuploidy, which is the leading cause of miscarriage and congenital birth defects in humans. The Aurora kinases, which include Aurora-A, Aurora-B, and Aurora-C, are highly conserved serine-threonine kinases that play essential roles in centrosome function, chromosome segregation, and cytokinesis during mitosis and meiosis. While Aurora-A and Aurora-B have been extensively studied in mitosis, the role of Aurora-C in meiosis is only now starting to be revealed. For example, the perturbation of Aurora-C kinase activity by microinjection of Aurora-C-kinase-dead mutant mRNAs into mouse oocytes induced multiple defects, including chromosome misalignment, abnormal kinetochore-microtubule attachment, premature chromosome segregation, and failure of cytokinesis during meiotic division. However, the analysis of such defects is complicated by the possibility that Aurora-B may be present in mammalian germ cells. Interestingly, a homozygous mutation of Aurora-C in humans leads to the production of large-headed polyploid spermatozoa and causes male infertility, but homozygous females are fertile. Mouse studies regarding the roles of Aurora-B and Aurora-C in female meiotic divisions have yielded inconsistent results, and it has proven difficult to explain why homozygous human females have no significant clinical phenotype. In this review, we will discuss the controversial status of Aurora-B in oocytes and the possible role of Aurora-C during meiotic division.

  17. The first accurate description of an aurora

    Science.gov (United States)

    Schröder, Wilfried

    2006-12-01

    As technology has advanced, the scientific study of auroral phenomena has increased by leaps and bounds. A look back at the earliest descriptions of aurorae offers an interesting look into how medieval scholars viewed the subjects that we study.Although there are earlier fragmentary references in the literature, the first accurate description of the aurora borealis appears to be that published by the German Catholic scholar Konrad von Megenberg (1309-1374) in his book Das Buch der Natur (The Book of Nature). The book was written between 1349 and 1350.

  18. High Speed IO using Xilinx Aurora

    OpenAIRE

    Nyman, Jeremia

    2013-01-01

    A VHDL evaluation platform and interface to the Xilinx Aurora 8b/10b IP has been designed, tested and evaluated. The evaluation platform takes an arbitrary amount of data sources and sends the data over 1,2,4 or 8 multi gigabit serial lanes, using the Aurora 8b/10b protocol. A lightweight communications protocol for point-to-point data transfer, error detection and recovery is used to maintain a reliable and efficient transmission scheme. Priority between sources sharing the serial link is al...

  19. Aurora B interacts with NIR-p53, leading to p53 phosphorylation in its DNA-binding domain and subsequent functional suppression.

    Science.gov (United States)

    Wu, Liming; Ma, Chi A; Zhao, Yongge; Jain, Ashish

    2011-01-21

    NIR (novel INHAT repressor) is a transcriptional co-repressor with inhibitor of histone acetyltransferase (INHAT) activity and has previously been shown to physically interact with and suppress p53 transcriptional activity and function. However, the mechanism by which NIR suppresses p53 is not completely understood. Using a proteomic approach, we have identified the Aurora kinase B as a novel binding partner of NIR. We show that Aurora B, NIR and p53 exist in a protein complex in which Aurora B binds to NIR, thus also indirectly associates with p53. Functionally, overexpression of Aurora B or NIR suppresses p53 transcriptional activity, and depletion of Aurora B or NIR causes p53-dependent apoptosis and cell growth arrest, due to the up-regulation of p21 and Bax. We then demonstrate that Aurora B phosphorylates multiple sites in the p53 DNA-binding domain in vitro, and this phosphorylation probably also occurs in cells. Importantly, the Aurora B-mediated phosphorylation on Ser(269) or Thr(284) significantly compromises p53 transcriptional activity. Taken together, these results provide novel insight into NIR-mediated p53 suppression and also suggest an additional way for p53 regulation.

  20. The transcription factor YY1 is a novel substrate for Aurora B kinase at G2/M transition of the cell cycle.

    Directory of Open Access Journals (Sweden)

    Ari Kassardjian

    Full Text Available Yin Yang 1 (YY1 is a ubiquitously expressed and highly conserved multifunctional transcription factor that is involved in a variety of cellular processes. Many YY1-regulated genes have crucial roles in cell proliferation, differentiation, apoptosis, and cell cycle regulation. Numerous mechanisms have been shown to regulate the function of YY1, such as DNA binding affinity, subcellular localization, and posttranslational modification including phosphorylation. Polo-like kinase 1(Plk1 and Casein kinase 2α (CK2 α were the first two kinases identified to phosphorylate YY1. In this study, we identify a third kinase. We report that YY1 is a novel substrate of the Aurora B kinase both in vitro and in vivo. Serine 184 phosphorylation of YY1 by Aurora B is cell cycle regulated and peaks at G2/M and is rapidly dephosphorylated, likely by protein phosphatase 1 (PP1 as the cells enter G1. Aurora A and Aurora C can also phosphorylate YY1 in vitro, but at serine/threonine residues other than serine 184. We present evidence that phosphorylation of YY1 in the central glycine/alanine (G/A-rich region is important for DNA binding activity, with a potential phosphorylation/acetylation interplay regulating YY1 function. Given their importance in mitosis and overexpression in human cancers, Aurora kinases have been identified as promising therapeutic targets. Increasing our understanding of Aurora substrates will add to the understanding of their signaling pathways.

  1. Proyecto Aurora: Building a Community of Women.

    Science.gov (United States)

    Noya, Gladys R. Capella

    1997-01-01

    Describes the development of Proyecto Aurora, a program to develop and implement educational, support, and research programs to benefit low-income women in Puerto Rico. Portraits of some clients illustrate the rewards and challenges of working with this community and furthering their educational experiences and opportunities. (SLD)

  2. A photometric model for predicting the sky glow of greenhouses

    NARCIS (Netherlands)

    Alferdinck, J.W.A.M.; Janssen, E.G.O.N.; Zonneveldt, L.; Ruigrok, J.

    2006-01-01

    many greenhouses use artificial light to grow plants. Part of this light escapes, scatters in the sky and causes sky glow. Residents in the vicinity complain about the absence of natural darkness. A light scatter model is developed in order to quantify the dose of the sky glow. The luminance of the

  3. Acting green elicits a literal warm glow

    Science.gov (United States)

    Taufik, Danny; Bolderdijk, Jan Willem; Steg, Linda

    2015-01-01

    Environmental policies are often based on the assumption that people only act environmentally friendly if some extrinsic reward is implicated, usually money. We argue that people might also be motivated by intrinsic rewards: doing the right thing (such as acting environmentally friendly) elicits psychological rewards in the form of positive feelings, a phenomenon known as warm glow. Given the fact that people's psychological state may affect their thermal state, we expected that this warm glow could express itself quite literally: people who act environmentally friendly may perceive the temperature to be higher. In two studies, we found that people who learned they acted environmentally friendly perceived a higher temperature than people who learned they acted environmentally unfriendly. The underlying psychological mechanism pertains to the self-concept: learning you acted environmentally friendly signals to yourself that you are a good person. Together, our studies show that acting environmentally friendly can be psychologically rewarding, suggesting that appealing to intrinsic rewards can be an alternative way to encourage pro-environmental actions.

  4. Glow discharge based device for solving mazes

    Energy Technology Data Exchange (ETDEWEB)

    Dubinov, Alexander E., E-mail: dubinov-ae@yandex.ru; Mironenko, Maxim S.; Selemir, Victor D. [Russian Federal Nuclear Center − All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation); Sarov Institute of Physics and Technology (SarFTI) of National Research Nuclear University “MEPhI,” Sarov, Nizhni Novgorod region 607188 (Russian Federation); Maksimov, Artem N.; Pylayev, Nikolay A. [Russian Federal Nuclear Center − All-Russian Scientific and Research Institute of Experimental Physics (RFNC-VNIIEF), Sarov, Nizhni Novgorod region 607188 (Russian Federation)

    2014-09-15

    A glow discharge based device for solving mazes has been designed and tested. The device consists of a gas discharge chamber and maze-transformer of radial-azimuth type. It allows changing of the maze pattern in a short period of time (within several minutes). The device has been tested with low pressure air. Once switched on, a glow discharge has been shown to find the shortest way through the maze from the very first attempt, even if there is a section with potential barrier for electrons on the way. It has been found that ionization waves (striations) can be excited in the maze along the length of the plasma channel. The dependancy of discharge voltage on the length of the optimal path through the maze has been measured. A reduction in discharge voltage with one or two potential barriers present has been found and explained. The dependency of the magnitude of discharge ignition voltage on the length of the optimal path through the maze has been measured. The reduction of the ignition voltage with the presence of one or two potential barriers has been observed and explained.

  5. Electron heating in atmospheric pressure glow discharges

    Science.gov (United States)

    Stark, Robert H.; Schoenbach, Karl H.

    2001-04-01

    The application of nanosecond voltage pulses to weakly ionized atmospheric pressure plasmas allows heating the electrons without considerably increasing the gas temperature, provided that the duration of the pulses is less than the critical time for the development of glow-to-arc transitions. The shift in the electron energy distribution towards higher energies causes a temporary increase in the ionization rate, and consequently a strong rise in electron density. This increase in electron density is reflected in an increased decay time of the plasma after the pulse application. Experiments in atmospheric pressure air glow discharges with gas temperatures of approximately 2000 K have been performed to explore the electron heating effect. Measurements of the temporal development of the voltage across the discharge and the optical emission in the visible after applying a 10 ns high voltage pulse to a weakly ionized steady state plasma demonstrated increasing plasma decay times from tens of nanoseconds to microseconds when the pulsed electric field was raised from 10 to 40 kV/cm. Temporally resolved photographs of the discharge have shown that the plasma column expands during this process. The nonlinear electron heating effect can be used to reduce the power consumption in a repetitively operated air plasma considerably compared to a dc plasma operation. Besides allowing power reduction, pulsed electron heating also has the potential to enhance plasma processes, which require elevated electron energies, such as excimer generation for ultraviolet lamps.

  6. High expression of nuclear survivin and Aurora B predicts poor overall survival in patients with head and neck squamous cell cancer

    Energy Technology Data Exchange (ETDEWEB)

    Erpolat, O.P.; Akmansu, M. [Medical School of Gazi Univ., Besevler-Ankara (Turkey). Dept. of Radiation Oncology; Gocun, P.U.; Karakus, E.; Akyol, G. [Medical School of Gazi Univ., Besevler-Ankara (Turkey). Dept. of Pathology

    2012-03-15

    Survivin is one of the apoptosis inhibitor proteins. Together with Aurora B, it also plays a role in regulating several aspects of mitosis. High expression of these markers is correlated with malignant behavior of various cancers and resistance to therapy. Our aim was to evaluate the prognostic role of these markers in head and neck cancers. We evaluated the expression of Aurora B and survivin in tissue specimens of 58 patients with head and neck squamous cell carcinoma using immunohistochemistry. Patients who showed high expression of cytoplasmic and nuclear survivin and Aurora B had significantly shorter overall survival (p = 0.036, p < 0.000, p = 0.032, respectively). In multivariate analysis, high expression of nuclear survivin was the only independent negative prognostic factor (p = 0.024). Moreover, it was found that high co-expression of nuclear survivin and Aurora B had a negative effect on survival in univariate (p < 0.000) and multivariate (p < 0.000) analyses. The negative prognostic values of high expression of Aurora B and high co-expression of nuclear survivin and Aurora B on survival were shown. These findings suggest that co-expression of nuclear survivin and Aurora B can be useful diagnostic markers and therapeutic targets for head and neck squamous cell carcinoma. However, further studies with a larger number of patients in a more homogeneous disease group are needed to confirm the conclusion.

  7. Atmospheric Pressure Glow Discharge with Liquid Electrode

    Science.gov (United States)

    Tochikubo, Fumiyoshi

    2013-09-01

    Nonthermal atmospheric pressure plasmas in contact with liquid are widely studied aiming variety of plasma applications. DC glow discharge with liquid electrode is an easy method to obtain simple and stable plasma-liquid interface. When we focus attention on liquid-phase reaction, the discharge system is considered as electrolysis with plasma electrode. The plasma electrode will supply electrons and positive ions to the liquid surface in a different way from the conventional metal electrode. However, the phenomena at plasma-liquid interface have not been understood well. In this work, we studied physical and chemical effect in liquid induced by dc atmospheric pressure glow discharge with liquid electrode. The experiment was carried out using H-shaped Hoffman electrolysis apparatus filled with electrolyte, to separate the anodic and cathodic reactions. Two nozzle electrodes made of stainless steel are set about 2 mm above the liquid surface. By applying a dc voltage between the nozzle electrodes, dc glow discharges as plasma electrodes are generated in contact with liquid. As electrolyte, we used aqueous solutions of NaCl, Na2SO4, AgNO3 and HAuCl4. AgNO3 and HAuCl4 are to discuss the reduction process of metal ions for synthesis of nanoparticles (NPs). OH radical generation yield in liquid was measured by chemical probe method using terephthalic acid. Discharge-induced liquid flow was visualized by Schlieren method. Electron irradiation to liquid surface (plasma cathode) generated OH- and OH radical in liquid while positive ion irradiation (plasma anode) generated H+ and OH radical. The generation efficiency of OH radical was better with plasma anode. Both Ag NPs in AgNO3 and Au NPs in HAuCl4 were synthesized with plasma cathode while only Au NPs were generated with plasma anode. Possible reaction process is qualitatively discussed. The discharge-induced liquid flow such as convection pattern was strongly influenced by the gas flow on the liquid surface. This work

  8. Aurora A's functions during mitotic exit: the Guess Who game

    Directory of Open Access Journals (Sweden)

    David eReboutier

    2015-12-01

    Full Text Available Until recently, the knowledge of Aurora A kinase functions during mitosis was limited to pre-metaphase events, particularly centrosome maturation, G2/M transition, and mitotic spindle assembly. However, an involvement of Aurora A in post-metaphase events was also suspected, but not clearly demonstrated due to the technical difficulty to perform the appropriate experiments. Recent developments of both an analog specific version of Aurora A, and of small molecule inhibitors have led to the first demonstration that Aurora A is required for the early steps of cytokinesis. As in pre-metaphase, Aurora A plays diverse functions during anaphase, essentially participating in astral microtubules dynamics and central spindle assembly and functioning. The present review describes the experimental systems used to decipher new functions of Aurora A during late mitosis and situate these functions into the context of cytokinesis mechanisms.

  9. ICIS and Aurora B coregulate the microtubule depolymerase Kif2a.

    Science.gov (United States)

    Knowlton, Anne L; Vorozhko, Valeriya V; Lan, Weijie; Gorbsky, Gary J; Stukenberg, P Todd

    2009-05-12

    Kinesins in the mitotic spindle play major roles in determining spindle shape, size, and bipolarity, although specific regulation of these kinesins at distinct locations on the spindle is poorly understood. So that the forces that are required for spindle bipolarity are balanced, microtubule-depolymerizing kinesins are tightly regulated. Aurora B kinase phosphorylates the neck regions of the kinesin-13 family microtubule depolymerases Kif2a and mitotic centromere-associated kinesin (MCAK) and inhibits their depolymerase activities. How they are reactivated and how this is controlled independently on different kinetochore fibers is unknown. We show that inner centromere Kin-I stimulator (ICIS), which stimulates the related depolymerase MCAK, can reactivate Kif2a after Aurora B inhibition. When antibodies that block the ability of ICIS to activate Kif2a are injected into cells, monopolar spindles are generated. This phenotype is rescued by coinjection of anti-Nuf2 antibodies. We have performed a structure-function analysis of the ICIS protein and find that the N terminus of ICIS binds Aurora B and its regulators INCENP and TD60, whereas a central region binds MCAK, Kif2a, and microtubules, suggesting a scaffold function for ICIS. These data argue that ICIS and the chromosomal passenger complex (CPC) regulate Kif2a depolymerase activity.

  10. Probiotic bacteria induce a 'glow of health'.

    Directory of Open Access Journals (Sweden)

    Tatiana Levkovich

    Full Text Available Radiant skin and hair are universally recognized as indications of good health. However, this 'glow of health' display remains poorly understood. We found that feeding of probiotic bacteria to aged mice induced integumentary changes mimicking peak health and reproductive fitness characteristic of much younger animals. Eating probiotic yogurt triggered epithelial follicular anagen-phase shift with sebocytogenesis resulting in thick lustrous fur due to a bacteria-triggered interleukin-10-dependent mechanism. Aged male animals eating probiotics exhibited increased subcuticular folliculogenesis, when compared with matched controls, yielding luxuriant fur only in probiotic-fed subjects. Female animals displayed probiotic-induced hyperacidity coinciding with shinier hair, a feature that also aligns with fertility in human females. Together these data provide insights into mammalian evolution and novel strategies for integumentary health.

  11. A model for explaining some features of shuttle glow

    Science.gov (United States)

    Peters, P. N.

    1985-01-01

    A solid state model is proposed which hopefully removes some of the objections to excited atoms being sources for light emanating from surfaces. Glow features are discussed in terms of excited oxygen atoms impinged on the surface, although other species could be treated similarly. Band formation, excited lifetime shortening and glow color are discussed in terms of this model. The model's inability to explain glow emanating above surfaces indicates a necessity for other mechanisms to satisfy this requirements. Several ways of testing the model are described.

  12. Spectrochemical analysis with DC glow discharges at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Broekaert, J.A.C., E-mail: jose.broekaert@chemie.uni-hamburg.de; Reinsberg, K.-G.

    2015-04-01

    A review on recent work and developments in dc glow discharges at atmospheric pressure when used as radiation sources for optical atomic spectrometry and mass spectrometry is given. Diagnostics and analytical features of dc glow discharges at atmospheric pressure between conductive solid electrodes as well as with a liquid as the cathode and flowing afterglow sources were described. Possibilities for the introduction of analytes in solutions, in the gaseous state and direct solids sampling were discussed. - Highlights: • The state-of-the-art and trends of development of dc glow discharges at atmospheric pressure for spectrochemical analysis are discussed.

  13. Three spacecraft observe Jupiter's glowing polar regions

    Science.gov (United States)

    1996-09-01

    The aurorae on Jupiter are like the Aurorae Borealis and Australis on the Earth, although visible only by ultraviolet light. They flicker in a similar way in response to variations in the solar wind of charged particles blowing from the Sun. While Galileo monitored the changing environment of particles and magnetism in Jupiter's vicinity, IUE recorded surprisingly large and rapid variations in the overall strength of the auroral activity. IUE's main 45-centimetre telescope did not supply images,but broke up the ultraviolet rays into spectra, like invisible rainbows, from which astrophysicists could deduce chemical compositions, motions and temperatures in the cosmic objects under examination. In the case of Jupiter's aurorae, the strongest emission came from activated hydrogen atoms at a wavelength of 1216 angstroms. The Hubble Space Telescope's contributions to the International Jupiter Watch included images showing variations in the form of the aurorae, and "close-up" spectra of parts of the auroral ovals. Astronomers will compare the flickering aurorae on Jupiter with concurrent monitoring of the Sun and the solar wind by the ESA-NASA SOHO spacecraft and several satellites of the Interagency Solar-Terrestrial Programme. It is notable that changes in auroral intensity by a factor of two or three occurred during the 1996 observational period, even though the Sun was in an exceptionally quiet phase, with very few sunspots. In principle, a watch on Jupiter's aurorae could become a valuable means of checking the long-range effects of solar activity, which also has important consequences for the Earth. The situation at Jupiter is quite different from the Earth's, with the moons strongly influencing the planet's space environment. But with Hubble busy with other work, any such Jupiter-monitoring programme will have to await a new ultraviolet space observatory. IUE observed Jupiter intensively in 1979-80 in conjunction with the visits of NASA's Voyager spacecraft, and

  14. Selective disruption of aurora C kinase reveals distinct functions from aurora B kinase during meiosis in mouse oocytes.

    Directory of Open Access Journals (Sweden)

    Ahmed Z Balboula

    2014-02-01

    Full Text Available Aurora B kinase (AURKB is the catalytic subunit of the chromosomal passenger complex (CPC, an essential regulator of chromosome segregation. In mitosis, the CPC is required to regulate kinetochore microtubule (K-MT attachments, the spindle assembly checkpoint, and cytokinesis. Germ cells express an AURKB homolog, AURKC, which can also function in the CPC. Separation of AURKB and AURKC function during meiosis in oocytes by conventional approaches has not been successful. Therefore, the meiotic function of AURKC is still not fully understood. Here, we describe an ATP-binding-pocket-AURKC mutant, that when expressed in mouse oocytes specifically perturbs AURKC-CPC and not AURKB-CPC function. Using this mutant we show for the first time that AURKC has functions that do not overlap with AURKB. These functions include regulating localized CPC activity and regulating chromosome alignment and K-MT attachments at metaphase of meiosis I (Met I. We find that AURKC-CPC is not the sole CPC complex that regulates the spindle assembly checkpoint in meiosis, and as a result most AURKC-perturbed oocytes arrest at Met I. A small subset of oocytes do proceed through cytokinesis normally, suggesting that AURKC-CPC is not the sole CPC complex during telophase I. But, the resulting eggs are aneuploid, indicating that AURKC is a critical regulator of meiotic chromosome segregation in female gametes. Taken together, these data suggest that mammalian oocytes contain AURKC to efficiently execute meiosis I and ensure high-quality eggs necessary for sexual reproduction.

  15. Glow phenomenon surrounding the vertical stabilizer and OMS pods

    Science.gov (United States)

    1994-01-01

    This 35mm frame, photographed as the Space Shuttle Columbia was orbiting Earth during a 'night' pass, documents the glow phenomenon surrounding the vertical stabilizer and the Orbital Maneuvering System (OMS) pods of the spacecraft.

  16. Multifunctional Glow Discharge Analyzer for Spacecraft Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) and Penn State University (PSU) propose to develop a highly sensitive spectrometer based on glow discharge emission for the...

  17. tgcd: An R package for analyzing thermoluminescence glow curves

    Science.gov (United States)

    Peng, Jun; Dong, ZhiBao; Han, FengQing

    Thermoluminescence (TL) glow curves are widely used in dosimetric studies. Many commercial and free-distributed programs are used to deconvolute TL glow curves. This study introduces an open-source R package tgcd to conduct TL glow curve analysis, such as kinetic parameter estimation, glow peak simulation, and peak shape analysis. TL glow curves can be deconvoluted according to the general-order empirical expression or the semi-analytical expression derived from the one trap-one recombination center (OTOR) model based on the Lambert W function by using a modified Levenberg-Marquardt algorithm from which any of the parameters can be constrained or fixed. The package provides an interactive environment to initialize parameters and offers an automated "trial-and-error" protocol to obtain optimal fit results. First-order, second-order, and general-order glow peaks (curves) are simulated according to a number of simple kinetic models. The package was developed using a combination of Fortran and R programming languages to improve efficiency and flexibility.

  18. Solar activity around AD 775 from aurorae and radiocarbon

    CERN Document Server

    Neuhaeuser, Ralph

    2015-01-01

    A large variation in 14 C around AD 775 has been considered to be caused by one or more solar super-flares within one year. We critically review all known aurora reports from Europe as well as the Near, Middle, and Far East from AD 731 to 825 and find 39 likely true aurorae plus four more potential aurorae and 24 other reports about halos, meteors, thunderstorms etc., which were previously misinterpreted as aurorae or misdated; we assign probabilities for all events according to five aurora criteria. We find very likely true aurorae in AD 743, 745, 762, 765, 772, 773, 793, 796, 807, and 817. There were two aurorae in the early 770s observed near Amida (now Diyarbakir in Turkey near the Turkish-Syrian border), which were not only red, but also green-yellow - being at a relatively low geo-magnetic latidude, they indicate a relatively strong solar storm. However, it cannot be argued that those aurorae (geo-magnetical latitude 43 to 50 deg, considering five different reconstructions of the geo-magnetic pole) coul...

  19. Advances in the Remote Glow Discharge Experiment

    Science.gov (United States)

    Dominguez, Arturo; Zwicker, A.; Rusaits, L.; McNulty, M.; Sosa, Carl

    2014-10-01

    The Remote Glow Discharge Experiment (RGDX) is a DC discharge plasma with variable pressure, end-plate voltage and externally applied axial magnetic field. While the experiment is located at PPPL, a webcam displays the live video online. The parameters (voltage, magnetic field and pressure) can be controlled remotely in real-time by opening a URL which shows the streaming video, as well as a set of Labview controls. The RGDX is designed as an outreach tool that uses the attractive nature of a plasma in order to reach a wide audience and extend the presence of plasma physics and fusion around the world. In March 2014, the RGDX was made publically available and, as of early July, it has had approximately 3500 unique visits from 107 countries and almost all 50 US states. We present recent upgrades, including the ability to remotely control the distance between the electrodes. These changes give users the capability of measuring Paschen's Law remotely and provides a comprehensive introduction to plasma physics to those that do not have access to the necessary equipment.

  20. Aurora kinases are expressed in medullary thyroid carcinoma (MTC and their inhibition suppresses in vitro growth and tumorigenicity of the MTC derived cell line TT

    Directory of Open Access Journals (Sweden)

    Morrone Stefania

    2011-09-01

    Full Text Available Abstract Background The Aurora kinase family members, Aurora-A, -B and -C, are involved in the regulation of mitosis, and alterations in their expression are associated with cell malignant transformation. To date no information on the expression of these proteins in medullary thyroid carcinoma (MTC are available. We here investigated the expression of the Aurora kinases in human MTC tissues and their potential use as therapeutic targets. Methods The expression of the Aurora kinases in 26 MTC tissues at different TNM stages was analyzed at the mRNA level by quantitative RT-PCR. We then evaluated the effects of the Aurora kinase inhibitor MK-0457 on the MTC derived TT cell line proliferation, apoptosis, soft agar colony formation, cell cycle and ploidy. Results The results showed the absence of correlation between tumor tissue levels of any Aurora kinase and tumor stage indicating the lack of prognostic value for these proteins. Treatment with MK-0457 inhibited TT cell proliferation in a time- and dose-dependent manner with IC50 = 49.8 ± 6.6 nM, as well as Aurora kinases phosphorylation of substrates relevant to the mitotic progression. Time-lapse experiments demonstrated that MK-0457-treated cells entered mitosis but were unable to complete it. Cytofluorimetric analysis confirmed that MK-0457 induced accumulation of cells with ≥ 4N DNA content without inducing apoptosis. Finally, MK-0457 prevented the capability of the TT cells to form colonies in soft agar. Conclusions We demonstrate that Aurora kinases inhibition hampered growth and tumorigenicity of TT cells, suggesting its potential therapeutic value for MTC treatment.

  1. Source of the dayside cusp aurora

    Science.gov (United States)

    Mende, S. B.; Frey, H. U.; Angelopoulos, V.

    2016-08-01

    Monochromatic all-sky imagers at South Pole and other Antarctic stations of the Automatic Geophysical Observatory chain recorded the aurora in the region where the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites crossed the dayside magnetopause. In several cases the magnetic field lines threading the satellites when mapped to the atmosphere were inside the imagers' field of view. From the THEMIS magnetic field and the plasma density measurements, we were able to locate the position of the magnetopause crossings and map it to the ionosphere using the Tsyganenko-96 field model. Field line mapping is reasonably accurate on the dayside subsolar region where the field is strong, almost dipolar even though compressed. From these coordinated observations, we were able to prove that the dayside cusp aurora of high 630 nm brightness is on open field lines, and it is therefore direct precipitation from the magnetosheath. The cusp aurora contained significant highly structured N2+ 427.8 nm emission. The THEMIS measurements of the magnetosheath particle energy and density taken just outside the magnetopause compared to the intensity of the structured N2+ 427.8 nm emissions showed that the precipitating magnetosheath particles had to be accelerated. The most likely electron acceleration mechanism is by dispersive Alfvén waves propagating along the field line. Wave-accelerated suprathermal electrons were seen by FAST and DMSP. The 427.8 nm wavelength channel also shows the presence of a lower latitude hard-electron precipitation zone originating inside the magnetosphere.

  2. Simultaneous optical and satellite observations of auroras in the mantle: Case study

    Science.gov (United States)

    Safargaleev, V. V.; Mitrofanov, V. M.; Roldugin, A. V.

    2016-11-01

    The all-sky camera data obtained in Barentsburg (Spitsbergen Archipelago) are compared with specific features of electron and ion precipitations on the DMSP F18 satellite during its flight within the camera field of view on December 15, 2012. Before arriving at the cusp from the mantle side, the satellite detects two outbursts of precipitating particles. The burst of mantle precipitations far from the cusp is observed simultaneously in both ionic and electronic components. In the ionosphere related to the satellite, no auroras are detected, which is likely due to the low intensity of the flux of precipitating electrons and their low energy (80 eV). Near the cusp, a more intensive burst of precipitations of higher-energy electrons (140 eV) is accompanied by an almost complete "locking" of ions. This burst of mantle precipitations is related to the faint luminous structure in the ionosphere. The ion locking is indicative of the accelerating potential difference in the force tube, which is based on the glowing region. The luminous structure is an element of the so-called "polewar moving auroral forms," which is related in the literature to the reconnection in the daytime magnetopause. The possible relation of the observed phenomena to the reconnected magnetic force tubes, which drift from the cusp in the antisolar direction, is also confirmed by the dispersion of ionic precipitations, i.e., an increase in ion energy as the satellite approaches to the cusp.

  3. Jovian-like aurorae on Saturn.

    Science.gov (United States)

    Stallard, Tom; Miller, Steve; Melin, Henrik; Lystrup, Makenzie; Cowley, Stan W H; Bunce, Emma J; Achilleos, Nicholas; Dougherty, Michele

    2008-06-19

    Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its magnetic field (although other processes form aurorae at both planets). At Saturn, only the main auroral oval has previously been observed and there remains much debate over its origin. Here we report the discovery of a secondary oval at Saturn that is approximately 25 per cent as bright as the main oval, and we show this to be caused by interaction with the middle magnetosphere around the planet. This is a weak equivalent of Jupiter's main oval, its relative dimness being due to the lack of as large a source of ions as Jupiter's volcanic moon Io. This result suggests that differences seen in the auroral emissions from Saturn and Jupiter are due to scaling differences in the conditions at each of these two planets, whereas the underlying formation processes are the same.

  4. Tanshinones inhibit the growth of breast cancer cells through epigenetic modification of Aurora A expression and function.

    Directory of Open Access Journals (Sweden)

    Yi Gong

    Full Text Available The objectives of this study were to evaluate the effects of tanshinones from a Chinese herb Salvia Miltiorrhiza on the growth of breast cancer cells, and to elucidate cellular and molecular mechanisms of action. Tanshinones showed the dose-dependent effect on the growth inhibition of breast cancer cells in vitro, with tanshinone I (T1 the most potent agent. T1 was also the only tanshinone to have potent activity in inhibiting the growth of the triple-negative breast cancer cell line MDA-MB231. T1 caused cell cycle arrests of both estrogen-dependent and estrogen-independent cell lines associated with alterations of cyclinD, CDK4 and cyclinB, and induced breast cancer cell apoptosis associated with upregulation of c-PARP and downregulation of survivin and Aurora A. Among these associated biomarkers, Aurora A showed the most consistent pattern with the anti-growth activity of tanshinones. Overexpression of Aurora A was also verified in breast tumors. The gene function assay showed that knockdown of Aurora A by siRNA dramatically reduced the growth-inhibition and apoptosis-induction activities of T1, suggesting Aurora A as an important functional target of T1 action. On the other hand, tanshinones had much less adverse effects on normal mammary epithelial cells. Epigenetic mechanism studies showed that overexpression of Aurora A gene in breast cancer cells was not regulated by gene promoter DNA methylation, but by histone acetylation. T1 treatment significantly reduced acetylation levels of histone H3 associated with Aurora A gene. Our results supported the potent activity of T1 in inhibiting the growth of breast cancer cells in vitro in part by downregulation of Aurora A gene function. Our previous studies also demonstrated that T1 had potent anti-angiogenesis activity and minimal side effects in vivo. Altogether, this study warrants further investigation to develop T1 as an effective and safe agent for the therapy and prevention of breast cancer.

  5. Saturn's aurora observed by the Cassini camera at visible wavelengths

    CERN Document Server

    Dyudina, Ulyana A; Ewald, Shawn P; Wellington, Danika

    2015-01-01

    The first observations of Saturn's visible-wavelength aurora were made by the Cassini camera. The aurora was observed between 2006 and 2013 in the northern and southern hemispheres. The color of the aurora changes from pink at a few hundred km above the horizon to purple at 1000-1500 km above the horizon. The spectrum observed in 9 filters spanning wavelengths from 250 nm to 1000 nm has a prominent H-alpha line and roughly agrees with laboratory simulated auroras. Auroras in both hemispheres vary dramatically with longitude. Auroras form bright arcs between 70 and 80 degree latitude north and between 65 and 80 degree latitude south, which sometimes spiral around the pole, and sometimes form double arcs. A large 10,000-km-scale longitudinal brightness structure persists for more than 100 hours. This structure rotates approximately together with Saturn. On top of the large steady structure, the auroras brighten suddenly on the timescales of a few minutes. These brightenings repeat with a period of about 1 hour....

  6. Aurora B prevents chromosome arm separation defects by promoting telomere dispersion and disjunction.

    Science.gov (United States)

    Reyes, Céline; Serrurier, Céline; Gauthier, Tiphaine; Gachet, Yannick; Tournier, Sylvie

    2015-03-16

    The segregation of centromeres and telomeres at mitosis is coordinated at multiple levels to prevent the formation of aneuploid cells, a phenotype frequently observed in cancer. Mitotic instability arises from chromosome segregation defects, giving rise to chromatin bridges at anaphase. Most of these defects are corrected before anaphase onset by a mechanism involving Aurora B kinase, a key regulator of mitosis in a wide range of organisms. Here, we describe a new role for Aurora B in telomere dispersion and disjunction during fission yeast mitosis. Telomere dispersion initiates in metaphase, whereas disjunction takes place in anaphase. Dispersion is promoted by the dissociation of Swi6/HP1 and cohesin Rad21 from telomeres, whereas disjunction occurs at anaphase after the phosphorylation of condensin subunit Cnd2. Strikingly, we demonstrate that deletion of Ccq1, a telomeric shelterin component, rescued cell death after Aurora inhibition by promoting the loading of condensin on chromosome arms. Our findings reveal an essential role for telomeres in chromosome arm segregation.

  7. Simulation of nonstationary phenomena in atmospheric-pressure glow discharge

    Science.gov (United States)

    Korolev, Yu. D.; Frants, O. B.; Nekhoroshev, V. O.; Suslov, A. I.; Kas'yanov, V. S.; Shemyakin, I. A.; Bolotov, A. V.

    2016-06-01

    Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark and aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.

  8. ELECTRON TRANSPORT BEHAVIOURS IN THE NITROGEN DIRECT CURRENT GLOW DISCHARGE

    Institute of Scientific and Technical Information of China (English)

    ZHANG LIAN-ZHU; YU WEI; WANG JIU-LI; HAN LI; FU GUANG-SHENG

    2001-01-01

    A Monte Carlo simulation is presented to describe the electron transport behaviours in the nitrogen direct current glow discharge. The energy and angular distributions of the electrons at different positions of the cathode dark space are calculated; their energy and density distribution features throughout the entire discharge are discussed. The influence of molecular vibrational excitation, typical for electron-molecule collisions, has been studied and the elementary process of active species generation has been illustrated. The simulated results reveal that, in the cathode dark space, the high-energy electrons are mainly forward scattering and behave as a high-energy ‘electron beam'. The sharp increase of the number of secondary electrons plays an important role in producing active species at the interface between the cathode dark space and the negative glow region. The vibrational excitation enhances the energy loss of electrons in the negative glow region.

  9. Comparing investigation of pattern formation in glow and streamer DBD

    Science.gov (United States)

    Li, Ben; Ouyang, Jiting

    2016-11-01

    In this paper, we investigate the behaviors of patterns in dielectric barrier discharge (DBD) in glow and streamer regimes under different operating conditions (driving frequency and voltage) and external electric/magnetic field to explore the similarity and difference of pattern formation. It is found that patterns in both glow and streamer DBDs can be homogenized by decreasing the driving frequency to a low level. But filamentary streamers can still appear at low frequency when the voltage is much higher. With an additional lateral electric field, patterns in both regimes can be homogenized. However, an axial magnetic field makes the glow DBD homogeneous, while the streamer DBD decreases in filamentary size. In both regimes, dynamics and distribution of the space charges, rather than the surface charges, play the predominant role in the formation of DBD patterns. But the surface charges may also play an important role in pattern formation, especially in streamer DBD.

  10. Extension of spatiotemporal chaos in glow discharge-semiconductor systems

    Energy Technology Data Exchange (ETDEWEB)

    Akhmet, Marat, E-mail: marat@metu.edu.tr; Fen, Mehmet Onur [Department of Mathematics, Middle East Technical University, 06800 Ankara (Turkey); Rafatov, Ismail [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey)

    2014-12-15

    Generation of chaos in response systems is discovered numerically through specially designed unidirectional coupling of two glow discharge-semiconductor systems. By utilizing the auxiliary system approach, [H. D. I. Abarbanel, N. F. Rulkov, and M. M. Sushchik, Phys. Rev. E 53, 4528–4535 (1996)] it is verified that the phenomenon is not a chaos synchronization. Simulations demonstrate various aspects of the chaos appearance in both drive and response systems. Chaotic control is through the external circuit equation and governs the electrical potential on the boundary. The expandability of the theory to collectives of glow discharge systems is discussed, and this increases the potential of applications of the results. Moreover, the research completes the previous discussion of the chaos appearance in a glow discharge-semiconductor system [D. D. Šijačić U. Ebert, and I. Rafatov, Phys. Rev. E 70, 056220 (2004).].

  11. Hyperspectral all-sky imaging of auroras.

    Science.gov (United States)

    Sigernes, Fred; Ivanov, Yuriy; Chernouss, Sergey; Trondsen, Trond; Roldugin, Alexey; Fedorenko, Yury; Kozelov, Boris; Kirillov, Andrey; Kornilov, Ilia; Safargaleev, Vladimir; Holmen, Silje; Dyrland, Margit; Lorentzen, Dag; Baddeley, Lisa

    2012-12-03

    A prototype auroral hyperspectral all-sky camera has been constructed and tested. It uses electro-optical tunable filters to image the night sky as a function of wavelength throughout the visible spectrum with no moving mechanical parts. The core optical system includes a new high power all-sky lens with F-number equal to f/1.1. The camera has been tested at the Kjell Henriksen Observatory (KHO) during the auroral season of 2011/2012. It detects all sub classes of aurora above ~½ of the sub visual 1kR green intensity threshold at an exposure time of only one second. Supervised classification of the hyperspectral data shows promise as a new method to process and identify auroral forms.

  12. Were Greek temples oriented towards aurorae?

    Science.gov (United States)

    Liritzis, Ioannis; Vassiliou, Helen

    2006-02-01

    Two ancient Greek temples of Apollo at Bassae (Phigaleia, western Peloponnese, Greece), and Thermon at Aetolia, (Aetoloacarnania, western central Greece), have a north-south orientation of their main entrances. This is a rather rare alignment of temples in general and specifically of Apollo in classical Greece, where most of them have broadly an east-west orientation. Based on historical and mythological accounts, as well as astronomical orientation measurements, the northern direction orientation of these constructions may relate to the rare, albeit impressive, occurrence of aurorae borealis, the northern lights. These strong lights are attributed to god Apollo by the epithet ``hyperborean'', meaning to the northern lands. Attribution is supported by archaeomagnetic directional data accompanied by auroral occurrence during those times.

  13. Research Ship Aurora Australis Underway Meteorological Data, Quality Controlled

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Research Ship Aurora Australis Underway Meteorological Data (delayed ~10 days for quality control) are from the Shipboard Automated Meteorological and Oceanographic...

  14. Observation and theory of the radar aurora

    Energy Technology Data Exchange (ETDEWEB)

    Sahr, J.D.

    1990-01-01

    Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. Observations are presented of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, a simple nonlinear fluid theory of electrojet ion-acoustic waves is introduced, and reduced to a form of the three-wave interaction equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able to account for type 3 waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of the research a simple new radar transmitting mode and signal processing algorithm was generated which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies. Several new radar data analysis routines were developed, including the principally cross-beam image and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that type 3 waves originate at ordinary electrojet altitudes, not in the upper E region, from which it is concluded that the electrostatic ion-cyclotron mode does not generate type 3 waves. The measured height of type 3 waves and other spectral analyses provide support for the pure ion-acoustic theory of type 3 waves. Suggestions are offered for hardware improvements to the CUPRI radar, new experiments to test new and existing theories.

  15. Deregulated Expression of Aurora Kinases Is Not a Prognostic Biomarker in Papillary Thyroid Cancer Patients

    Science.gov (United States)

    Prinzi, Natalie; Sorrenti, Salvatore; Falvo, Laura; De Vito, Corrado; Catania, Antonio; Tartaglia, Francesco; Mocini, Renzo; Coccaro, Carmela; Alessandrini, Stefania; Barollo, Susi; Mian, Caterina; Antonelli, Alessandro; De Antoni, Enrico; D’Armiento, Massimino; Ulisse, Salvatore

    2015-01-01

    A number of reports indicated that Aurora-A or Aurora-B overexpression represented a negative prognostic factor in several human malignancies. In thyroid cancer tissues a deregulated expression of Aurora kinases has been also demonstrated, butno information regarding its possible prognostic role in differentiated thyroid cancer is available. Here, weevaluated Aurora-A and Aurora-B mRNA expression and its prognostic relevance in a series of 87 papillary thyroid cancers (PTC), with a median follow-up of 63 months. The analysis of Aurora-A and Aurora-B mRNA levels in PTC tissues, compared to normal matched tissues, revealed that their expression was either up- or down-regulatedin the majority of cancer tissues. In particular, Aurora-A and Aurora-B mRNA levels were altered, respectively, in 55 (63.2%) and 79 (90.8%) out of the 87 PTC analyzed.A significant positive correlation between Aurora-A and Aurora-B mRNAswas observed (p=0.001). The expression of both Aurora genes was not affected by the BRAFV600E mutation. Univariate, multivariate and Kaplan-Mayer analyses documented the lack of association between Aurora-A or Aurora-B expression and clinicopathological parameterssuch as gender, age, tumor size, histology, TNM stage, lymph node metastasis and BRAF status as well asdisease recurrences or disease-free interval. Only Aurora-B mRNA was significantly higher in T(3-4) tissues, with respect to T(1-2) PTC tissues. The data reported here demonstrate that the expression of Aurora kinases is deregulated in the majority of PTC tissues, likely contributing to PTC progression. However, differently from other human solid cancers, detection of Aurora-A or Aurora-B mRNAs is not a prognostic biomarker inPTC patients. PMID:25807528

  16. Immobilization of proteins on glow discharge treated polymers

    Science.gov (United States)

    Kiaei, D.; Safranj, A.; Chen, J. P.; Johnston, A. B.; Zavala, F.; Deelder, A.; Castelino, J. B.; Markovic, V.; Hoffman, A. S.

    Certain glow discharge-treated surfaces have been shown to enhance retention of adsorbed proteins. On the basis of this phenomenon, we have investigated the possibility of immobilizing (a) albumin for developing thromboresistant and non-fouling surfaces, (b) antibodies for immuno-diagnostic assays and (c) enzymes for various biosensors and industrial bioprocesses. Albumin retention was highest on surfaces treated with tetrafluoroethylene (TFE) compared to untreated surfaces or other glow discharge treatments studied. Preadsorption of albumin on TFE-treated surfaces resulted in low fibrinogen adsorption and platelet adhesion. IgG retention was also highest on TFE-treated surfaces. The lower detection limits of both malaria antigen and circulating anodic antigen of the schistosomiasis worm were enhanced following glow discharge treatment of the assay plates with TFE. Both TFE and tetrachloroethylene (TCE) glow discharge treated surfaces showed high retention of adsorbed horseradish peroxidase (HRP). However, the retained specific activity of HRP after adsorption on TCE-treated surfaces was remarkably higher than on TFE-treated surfaces.

  17. NEW DEVELOPMENT IN DOUBLE GLOW SURFACE ALLOYING TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Several kinds of special alloys are produced on the surfaces of iron and steels by using double glow surface alloying technology. Surface Ni-Cr-Mo-Nb alloy,surface precipitation hardening high speed steel and surface precipitation hardening stainless steel are introduced.

  18. Studying surface glow discharge for application in plasma aerodynamics

    Science.gov (United States)

    Tereshonok, D. V.

    2014-02-01

    Surface glow discharge in nitrogen between two infinite planar electrodes occurring on the same plane has been studied in the framework of a diffusion-drift model. Based on the results of numerical simulations, the plasma structure of this discharge is analyzed and the possibility of using it in plasma aerodynamics is considered.

  19. Aurora A kinase modulates actin cytoskeleton through phosphorylation of Cofilin: Implication in the mitotic process.

    Science.gov (United States)

    Ritchey, Lisa; Chakrabarti, Ratna

    2014-11-01

    Aurora A kinase regulates early mitotic events through phosphorylation and activation of a variety of proteins. Specifically, Aur-A is involved in centrosomal separation and formation of mitotic spindles in early prophase. The effect of Aur-A on mitotic spindles is mediated by the modulation of microtubule dynamics and association with microtubule binding proteins. In this study we show that Aur-A exerts its effects on spindle organization through the regulation of the actin cytoskeleton. Aurora A phosphorylates Cofilin at multiple sites including S(3) resulting in the inactivation of its actin depolymerizing function. Aur-A interacts with Cofilin in early mitotic phases and regulates its phosphorylation status. Cofilin phosphorylation follows a dynamic pattern during the progression of prophase to metaphase. Inhibition of Aur-A activity induced a delay in the progression of prophase to metaphase. Aur-A inhibitor also disturbed the pattern of Cofilin phosphorylation, which correlated with the mitotic delay. Our results establish a novel function of Aur-A in the regulation of actin cytoskeleton reorganization, through Cofilin phosphorylation during early mitotic stages.

  20. Aurora kinase A is not involved in CPEB1 phosphorylation and cyclin B1 mRNA polyadenylation during meiotic maturation of porcine oocytes.

    Science.gov (United States)

    Komrskova, Pavla; Susor, Andrej; Malik, Radek; Prochazkova, Barbora; Liskova, Lucie; Supolikova, Jaroslava; Hladky, Stepan; Kubelka, Michal

    2014-01-01

    Regulation of mRNA translation by cytoplasmic polyadenylation is known to be important for oocyte maturation and further development. This process is generally controlled by phosphorylation of cytoplasmic polyadenylation element binding protein 1 (CPEB1). The aim of this study is to determine the role of Aurora kinase A in CPEB1 phosphorylation and the consequent CPEB1-dependent polyadenylation of maternal mRNAs during mammalian oocyte meiosis. For this purpose, we specifically inhibited Aurora kinase A with MLN8237 during meiotic maturation of porcine oocytes. Using poly(A)-test PCR method, we monitored the effect of Aurora kinase A inhibition on poly(A)-tail extension of long and short cyclin B1 encoding mRNAs as markers of CPEB1-dependent cytoplasmic polyadenylation. Our results show that inhibition of Aurora kinase A activity impairs neither cyclin B1 mRNA polyadenylation nor its translation and that Aurora kinase A is unlikely to be involved in CPEB1 activating phosphorylation.

  1. Aurora kinase A is not involved in CPEB1 phosphorylation and cyclin B1 mRNA polyadenylation during meiotic maturation of porcine oocytes.

    Directory of Open Access Journals (Sweden)

    Pavla Komrskova

    Full Text Available Regulation of mRNA translation by cytoplasmic polyadenylation is known to be important for oocyte maturation and further development. This process is generally controlled by phosphorylation of cytoplasmic polyadenylation element binding protein 1 (CPEB1. The aim of this study is to determine the role of Aurora kinase A in CPEB1 phosphorylation and the consequent CPEB1-dependent polyadenylation of maternal mRNAs during mammalian oocyte meiosis. For this purpose, we specifically inhibited Aurora kinase A with MLN8237 during meiotic maturation of porcine oocytes. Using poly(A-test PCR method, we monitored the effect of Aurora kinase A inhibition on poly(A-tail extension of long and short cyclin B1 encoding mRNAs as markers of CPEB1-dependent cytoplasmic polyadenylation. Our results show that inhibition of Aurora kinase A activity impairs neither cyclin B1 mRNA polyadenylation nor its translation and that Aurora kinase A is unlikely to be involved in CPEB1 activating phosphorylation.

  2. Sporadic aurorae observed in East Asia

    Directory of Open Access Journals (Sweden)

    D. M. Willis

    2007-03-01

    aurorae observed in the United States during the interval AD 1880–1940. The localised nature and spatial structure of some sporadic aurorae observed in East Asia is indicated by the use of descriptive terms such as "lightning", "rainbow", "streak" and "grid".

  3. Functional analysis of phosphorylation of the mitotic centromere-associated kinesin by Aurora B kinase in human tumor cells.

    Science.gov (United States)

    Ritter, Andreas; Sanhaji, Mourad; Friemel, Alexandra; Roth, Susanne; Rolle, Udo; Louwen, Frank; Yuan, Juping

    2015-01-01

    Mitotic centromere-associated kinesin (MCAK) is the best characterized member of the kinesin-13 family and plays important roles in microtubule dynamics during mitosis. Its activity and subcellular localization is tightly regulated by an orchestra of mitotic kinases, such as Aurora B. It is well known that serine 196 of MCAK is the major phosphorylation site of Aurora B in Xenopus leavis extracts and that this phosphorylation regulates its catalytic activity and subcellular localization. In the current study, we have addressed the conserved phosphorylation site serine 192 in human MCAK to characterize its function in more depth in human cancer cells. Our data confirm that S192 is the major phosphorylation site of Aurora B in human MCAK and that this phosphorylation has crucial roles in regulating its catalytic activity and localization at the kinetochore/centromere region in mitosis. Interfering with this phosphorylation leads to a delayed progression through prometa- and metaphase associated with mitotic defects in chromosome alignment and segregation. We show further that MCAK is involved in directional migration and invasion of tumor cells, and interestingly, interference with the S192 phosphorylation affects this capability of MCAK. These data provide the first molecular explanation for clinical observation, where an overexpression of MCAK was associated with lymphatic invasion and lymph node metastasis in gastric and colorectal cancer patients.

  4. Skp2 is required for Aurora B activation in cell mitosis and spindle checkpoint.

    Science.gov (United States)

    Wu, Juan; Huang, Yu-Fan; Zhou, Xin-Ke; Zhang, Wei; Lian, Yi-Fan; Lv, Xiao-Bin; Gao, Xiu-Rong; Lin, Hui-Kuan; Zeng, Yi-Xin; Huang, Jian-Qing

    2015-01-01

    The Aurora B kinase plays a critical role in cell mitosis and spindle checkpoint. Here, we showed that the ubiquitin E3-ligase protein Skp2, also as a cell-cycle regulatory protein, was required for the activation of Aurora B and its downstream protein. When we restored Skp2 knockdown Hela cells with Skp2 and Skp2-LRR E3 ligase dead mutant we found that Skp2 could rescue the defect in the activation of Aurora B, but the mutant failed to do so. Furthermore, we discovered that Skp2 could interact with Aurora B and trigger Aurora B Lysine (K) 63-linked ubiquitination. Finally, we demonstrated the essential role of Skp2 in cell mitosis progression and spindle checkpoint, which was Aurora B dependent. Our results identified a novel ubiquitinated substrate of Skp2, and also indicated that Aurora B ubiquitination might serve as an important event for Aurora B activation in cell mitosis and spindle checkpoint.

  5. Study of short atmospheric pressure dc glow microdischarge in air

    Science.gov (United States)

    Kudryavtsev, Anatoly; Bogdanov, Eugene; Chirtsov, Alexander; Emelin, Sergey

    2011-10-01

    The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen and oxygen atoms; ozone molecule; and different nitrogen and oxygen ions with different plasmochemical reactions between them. Simulations predicted the main regions of the dc glow discharges including cathode and anode sheath and plasma of negative glow, Faraday dark space and transition region. Gas heating plays an important role in shaping the discharge profiles. The results of experiments and simulations of short (without positive column) atmospheric pressure dc glow discharge in air are presented. We used metal steel electrodes with a gap of 5-100 microns. The experimental voltage-current characteristic's (VAC) have a constant or slightly increasing form at low gap. The most stable microdischarges were burning with a flat cathode and rounded anode, when the length of the discharge is automatically established near the minimum of the Paschen curve by changing their binding on the anode. In this case microdischarge was stable and it had growing VAC. For simulations we used 2D fluid model with kinetic description of electrons. We solved the balance equations for the vibrationally- and the electronically-excited states of a nitrogen and oxygen molecules; nitrogen

  6. Solar wind influence on Jupiter's aurora

    Science.gov (United States)

    Gyalay, Szilard; Vogt, Marissa F.; Withers, Paul; Bunce, Emma J.

    2016-10-01

    Jupiter's main auroral emission is driven by a system of corotation enforcement currents that arises to speed up outflowing Iogenic plasma and is not due to the magnetosphere-solar wind interaction like at Earth. The solar wind is generally expected to have only a small influence on Jupiter's magnetosphere and aurora compared to the influence of rotational stresses due to the planet's rapid rotation. However, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the position and brightness of the UV auroral emissions. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter we have identified intervals of high and low solar wind dynamic pressure in the Galileo dataset, and use this information to quantify how a magnetospheric compression affects the magnetospheric field configuration. We have developed separate spatial fits to the compressed and nominal magnetic field data, accounting for variations with radial distance and local time. These two fits can be used to update the flux equivalence mapping model of Vogt et al. (2011), which links auroral features to source regions in the middle and outer magnetosphere. The updated version accounts for changing solar wind conditions and provides a way to quantify the expected solar wind-induced variability in the ionospheric mapping of the main auroral emission, satellite footprints, and other auroral features. Our results are highly relevant to interpretation of the new auroral observations from the Juno mission.

  7. A Cell Biologist’s Field Guide to Aurora Kinase Inhibitors

    Directory of Open Access Journals (Sweden)

    Christian eDe Groot

    2015-12-01

    Full Text Available Aurora kinases are essential for cell division and are frequently misregulated in human cancers. Based on their potential as cancer therapeutics, a plethora of small molecule Aurora kinase inhibitors have been developed, with a subset having been adopted as tools in cell biology. Here, we fill a gap in the characterization of Aurora kinase inhibitors by using biochemical and cell-based assays to systematically profile a panel of 10 commercially available compounds with reported selectivity for Aurora A (MLN8054, MLN8237, MK-5108, MK-8745, Genentech Aurora Inhibitor 1, Aurora B (Hesperadin, ZM447439, AZD1152-HQPA, GSK1070916 or Aurora A/B (VX-680. We quantify the in vitro effect of each inhibitor on the activity of Aurora A alone, as well as Aurora A and Aurora B bound to fragments of their activators, TPX2 and INCENP, respectively. We also report kinome profiling results for a subset of these compounds to highlight potential off-target effects. In a cellular context, we demonstrate that immunofluorescence-based detection of LATS2 and histone H3 phospho-epitopes provides a facile and reliable means to assess potency and specificity of Aurora A versus Aurora B inhibition, and that G2 duration measured in a live imaging assay is a specific readout of Aurora A activity. Our analysis also highlights variation between HeLa, U2OS and hTERT-RPE1 cells that impacts selective Aurora A inhibition. For Aurora B, all 4 tested compounds exhibit excellent selectivity and do not significantly inhibit Aurora A at effective doses. For Aurora A, MK-5108 and MK-8745 are significantly more selective than the commonly used inhibitors MLN8054 and MLN8237. A crystal structure of an Aurora A/MK-5108 complex that we determined suggests the chemical basis for this higher specificity. Taken together, our quantitative biochemical and cell-based analyses indicate that AZD1152-HQPA and MK-8745 are the best current tools for selectively inhibiting Aurora B and Aurora A

  8. Making Sense of the Aurora: A Research Project

    Directory of Open Access Journals (Sweden)

    Robert Marc Friedman

    2012-05-01

    Full Text Available The article provides an introduction to a on-going research project based at University of Tromsø that seeks to analyze the history of efforts to make sense of the aurora borealis from the early 1700s through to the Cold War. Following brilliant displays of the northern lights in the early eighteenth century, natural philosophers strove to explain this phenomenon that evoked widespread fear and superstition. It was not until well into the twentieth century that consensual explanation emerged for this, one of the great enigmas in the history of science. From the start, the quest to explain the aurora borealis became enmeshed with patriotic science and nationalist sentiments. The history of efforts to understand the nature and cause of the aurora poses a number of thematic problems. Being a fleeting and at times rapidly changing phenomenon, only occasionally seen south of far-northern latitudes, the aurora needed to be constituted as an object able to be brought into the domain of rational science. Observational accounts of the aurora came most often from by personsliving or travelling in the far north or in the Arctic, but these persons were generally not trained scientists: Whose witnessing counted and how was authority negotiated among professional scientists and amateurs?

  9. Aurora Borealis, A Painting by Frederic Edwin Church

    Science.gov (United States)

    Love, J. J.

    2015-12-01

    This year marks the sesquicentennial anniversary of the end of the American Civil War. In 1865, the same year as the War's end, the great American landscape artist, Frederic Edwin Church, unveiled Aurora Borealis, a painting that depicts a fantastic, far-northern place, an auroral arch stretched across a quiet night-time sky, above dark mountains and a frozen sea. Church was born in Connecticut, lived in New York, and traveled to Labrador; he would have often seen the northern lights. Church might have also been influenced by the spectacular displays of aurora that were caused by some unusually intense magnetic storms in 1859. Aurora Borealis can certainly be interpreted in terms of 19th-century romanticism, scientific philosophy, and Arctic missions of exploration, all subjects of interest to Church. As with so many of his paintings, Church's meticulous attention to detail in Aurora Borealis reveals his deep admiration of nature. But his depiction of auroral light is a curious and possibly intentional departure from natural verisimilitude. Some art historians have suggested that Church painted Aurora Borealis as a subdued tribute to the end of the Civil War, with the drapery of auroral light forming an abstract representation of the American flag. If so, then colors of the flag have been unfurled across a cold and barren landscape, not in extravagant celebration, but in somber recognition of the reality of post-war desolation and an uncertain future.

  10. Glow Discharge Induced Hydroxyl Radical Degradation of 2-Naphthylamine

    Institute of Scientific and Technical Information of China (English)

    Lu Quanfang; Yu Jie; Gao Jinzhang; Yang Wu

    2005-01-01

    In an aqueous solution, normal electrolysis at high voltages switches over sponta-neously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, andaqueous electron, as well as several other active species. Hydroxyl radical directly attacks or-ganic contaminants to make them oxidized. In the present paper, 2-naphthylamine is eventuallydegraded into hydrogen carbonate and carbon dioxide. The degradation process is analyzed byusing an Ultraviolet (UV) absorption spectrum, high-performance liquid chromatography (HPLC)and chemical oxygen demand (COD). It is demonstrated that 2-naphthylamine (c0 =30 mg.1-1) iscompletely converted within 2h at 30℃ and 600 V by glow discharge electrolysis, and the degra-dation is strongly dependent upon the presence of ferrous ions. COD is ascended in the absenceof ferrous ions and descended in the presence of them.

  11. Self-Consistent Description of Nitrogen dc Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    傅广生; 王久丽; 于威; 韩理

    2002-01-01

    A self-consistent hybrid Monte Carlo fluid model is presented to describe the nitrogen dc glow discharge. The movement of fast electrons is simulated by the Monte Carlo method while the dynamics of slow electrons and ions is by fluid equations. The spatial features of the charged species and the corresponding electric field throughout the discharge have been calculated, which include the creation rates of ions and slow electrons, densities of the charged species, the electric field and the potential distribution. These closely related results can give a selfconsistent explanation of the discharge characteristics throughout the space of nitrogen dc glow discharge. The calculated ion density is also compared with the corresponding experimental result.

  12. Dust particle charge distribution in a stratified glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Sukhinin, Gennady I [Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Lavrentyev Ave., 1, Novosibirsk 630090 (Russian Federation); Fedoseev, Alexander V [Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Lavrentyev Ave., 1, Novosibirsk 630090 (Russian Federation); Ramazanov, Tlekkabul S [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty 050012 (Kazakhstan); Dzhumagulova, Karlygash N [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty 050012 (Kazakhstan); Amangaliyeva, Rauan Zh [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty 050012 (Kazakhstan)

    2007-12-21

    The influence of a highly pronounced non-equilibrium characteristic of the electron energy distribution function in a stratified dc glow discharge on the process of dust particle charging in a complex plasma is taken into account for the first time. The calculated particle charge spatial distribution is essentially non-homogeneous and it can explain the vortex motion of particles at the periphery of a dusty cloud obtained in experiments.

  13. The Use of DC Glow Discharges as Undergraduate Educational Tools

    Energy Technology Data Exchange (ETDEWEB)

    Stephanie A. Wissel and Andrew Zwicker, Jerry Ross, and Sophia Gershman

    2012-10-09

    Plasmas have a beguiling way of getting students excited and interested in physics. We argue that plasmas can and should be incorporated into the undergraduate curriculum as both demonstrations and advanced investigations of electromagnetism and quantum effects. Our device, based on a direct current (DC) glow discharge tube, allows for a number of experiments into topics such as electrical breakdown, spectroscopy, magnetism, and electron temperature.

  14. Inception of Snapover and Gas Induced Glow Discharges

    Science.gov (United States)

    Galofaro, J. T.; Vayner, B. V.; Degroot, W. A.; Ferguson, D. C.; Thomson, C. D.; Dennison, J. R.; Davies, R. E.

    2000-01-01

    Ground based experiments of the snapover phenomenon were conducted in the large vertical simulation chamber at the Glenn Research Center (GRC) Plasma Interaction Facility (PIF). Two Penning sources provided both argon and xenon plasmas for the experiments. The sources were used to simulate a variety of ionospheric densities pertaining to a spacecraft in a Low Earth Orbital (LEO) environment. Secondary electron emission is believed responsible for dielectric surface charging, and all subsequent snapover phenomena observed. Voltage sweeps of conductor potentials versus collected current were recorded in order to examine the specific charging history of each sample. The average time constant for sample charging was estimated between 25 and 50 seconds for all samples. It appears that current drops off by approximately a factor of 3 over the charging time of the sample. All samples charged in the forward and reverse bias directions, demonstrated hysteresis. Current jumps were only observed in the forward or positive swept voltage direction. There is large dispersion in tile critical snapover potential when repeating sweeps on any one sample. The current ratio for the first snapover region jumps between 2 and 4.6 times, with a standard deviation less than 1.6. Two of the samples showed even larger current ratios. It is believed the second large snapover region is due to sample outgassing. Under certain preset conditions, namely at the higher neutral gas background pressures, a perceptible blue-green glow was observed around the conductor. The glow is believed to be a result of secondary electrons undergoing collisions with an expelled tenuous cloud of gas, that is outgassed from the sample. Spectroscopic measurements of the glow discharge were made in an attempt to identify specific lines contributing to the observed glow.

  15. Ipl1/Aurora kinase suppresses S-CDK-driven spindle formation during prophase I to ensure chromosome integrity during meiosis.

    Directory of Open Access Journals (Sweden)

    Louise Newnham

    Full Text Available Cells coordinate spindle formation with DNA repair and morphological modifications to chromosomes prior to their segregation to prevent cell division with damaged chromosomes. Here we uncover a novel and unexpected role for Aurora kinase in preventing the formation of spindles by Clb5-CDK (S-CDK during meiotic prophase I and when the DDR is active in budding yeast. This is critical since S-CDK is essential for replication during premeiotic S-phase as well as double-strand break induction that facilitates meiotic recombination and, ultimately, chromosome segregation. Furthermore, we find that depletion of Cdc5 polo kinase activity delays spindle formation in DDR-arrested cells and that ectopic expression of Cdc5 in prophase I enhances spindle formation, when Ipl1 is depleted. Our findings establish a new paradigm for Aurora kinase function in both negative and positive regulation of spindle dynamics.

  16. Aurora Borealis Experiment (ABX): A Planeterrella for Education and Outreach

    Science.gov (United States)

    McNulty, Michael; Carpe, Andy; Zwicker, Andrew

    2013-10-01

    The Planeterrella is an experiment invented by Jean Lilensten of the Laboratoire de Planetologie de Grenoble in France designed to simulate aurorae of various planets. It is done by placing two differently sized aluminum spheres in a bell jar with a pressure of approximately 75 mTorr. Each sphere has magnets inside and is electrically biased. An electrode with the opposite electrical bias is inserted into the bell jar so that the voltage between them is on the order of 300 V. A plasma is then created and an aurora is formed around the magnetic poles of the spheres or near the edge of the electrode. We have made a modified version of the planeterrella, called the Aurora Borealis Experiment (ABX), based upon Lilensten's plans. We will present the technical details of the experiment and preliminary results of its use with a variety of different audiences.

  17. Applications to particle transport in the Earth`s aurora

    Energy Technology Data Exchange (ETDEWEB)

    Jasperse, J.R.

    1994-12-31

    The visual display of light called the aurora borealis occurs when energetic (1 to 100-keV) electrons, protons, and hydrogen atoms from the Earth`s magnetosphere enter the Earth`s upper atmosphere and collide with the ambient neutral particles. Two kinds of auroras occur in nature: those excited by incident electrons and those excited by incident protons and hydrogen atoms. In this paper, we consider only the latter. The proton-hydrogen aurora may be divided into two altitude regions: high altitudes ({approximately}250 to {approximately}600 km) where charge-changing collisions dominate and energy-loss collisions may be neglected and low altitudes ({approximately}100 to {approximately}250 km) where energy-loss collisions also become important and cause rapid energy degradation. The focus of this review is on the high-altitude region where the one-group approximation is valid.

  18. Method of computerized glow curve deconvolution for analysing thermoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, T [Division of General Education, Ashikaga Institute of Technology, Omae-cho 268-1, Ashikaga, Tochigi 326-8558 (Japan); Gartia, R K [Luminescence Dating Laboratory, Manipur University, Imphal 795003 (India)

    2003-11-07

    The conventional worldwide accepted method of computerized glow curve deconvolution based on the general order kinetics formalism has two fatal defects in systems where the trapping levels (two or more) have non-zero retrapping probability. The first one is ignoring the thermal connectivity between thermoluminescence (TL) peaks. This arises from the fact that under such a situation electrons trapped at one trapping level, once activated, can be retrapped in another thermally connected level via the conduction band during the recording of the glow curve. The other is the impossibility of obtaining a global minimum, in fitting the experimental TL with the theoretical one with existing techniques. This paper aims to provide answers to these defects. The first one can be overcome by resorting to rigorous analysis using appropriate mathematical rate equations describing the flow of charge carriers. Though the second defect cannot be overcome completely, one can obtain a reasonable fit, which may not be unique. The algorithm is tested for synthetic as well as experimental glow curves.

  19. Phenotypic screening approaches to develop Aurora kinase inhibitors: Drug Discovery perspectives

    Directory of Open Access Journals (Sweden)

    Carlos eMarugán

    2016-01-01

    Full Text Available Targeting mitotic regulators as a strategy to fight cancer implies the development of drugs against key proteins such as Aurora A and B. Current drugs which target mitosis through a general mechanism of action (stabilization/destabilization of microtubules, have several side effects (neutropenia, alopecia, emesis. Pharmaceutical companies aim at avoiding these unwanted effects by generating improved and selective drugs that increase the quality of life of the patients. However, the development of these drugs is an ambitious task that involves testing thousands of compounds through biochemical and cell-based assays. In addition, molecules usually target complex biological processes, involving several proteins and different molecular pathways, further emphasizing the need for high-throughput screening techniques and multiplexing technologies in order to identify drugs with the desired phenotype.We will briefly describe two multiplexing technologies (high-content imaging, microarrays and flow cytometry and two key processes for drug discovery research (assay development and validation following our own published industry quality standards. We will further focus on high-content imaging as a useful tool for phenotypic screening and will provide a concrete example of high-content imaging assay to detect Aurora A or B selective inhibitors discriminating the off-target effects related to inhibition of other cell cycle or non-cell cycle key regulators. Finally, we will describe other assays that can help to characterize the in vitro pharmacology of the inhibitors.

  20. Optical tomography of the aurora and EISCAT

    Directory of Open Access Journals (Sweden)

    H. U. Frey

    Full Text Available Tomographic reconstruction of the three-dimensional auroral arc emission is used to obtain vertical and horizontal distributions of the optical auroral emission. Under the given experimental conditions with a very limited angular range and a small number of observers, algebraic reconstruction methods generally yield better results than transform techniques. Different algebraic reconstruction methods are tested with an auroral arc model and the best results are obtained with an iterative least-square method adapted from emission-computed tomography. The observation geometry used during a campaign in Norway in 1995 is tested with the arc model and root-mean-square errors, to be expected under the given geometrical conditions, are calculated. Although optimum geometry was not used, root-mean-square errors of less than 2% for the images and of the order of 30% for the distribution could be obtained. The method is applied to images from real observations. The correspondence of original pictures and projections of the reconstructed volume is discussed, and emission profiles along magnetic field lines through the three-dimensionally reconstructed arc are calibrated into electron density profiles with additional EISCAT measurements. Including a background profile and the temporal changes of the electron density due to recombination, good agreement can be obtained between measured profiles and the time-sequence of calculated profiles. These profiles are used to estimate the conductivity distribution in the vicinity of the EISCAT site. While the radar can only probe the ionosphere along the radar beam, the three-dimensional tomography enables conductivity estimates in a large area around the radar site.

    Key words. Tomography · Aurora · EISCAT · Ionosphere · Conductivity

  1. Monitoring magnetosheath-magnetosphere interconnection topology from the aurora

    Directory of Open Access Journals (Sweden)

    P. E. Sandholt

    Full Text Available A strong southward rotation of the IMF (BZ from 5 to -6 nT in ~ 20 s on 4 January 1995 caused an abrupt reconfiguration of midday aurorae and plasma convection consisting of the following: (1 the red-line aurora associated with magnetosheath plasma transfer at the low-latitude magnetopause appeared at the same time that (2 the green-line aurora from precipitating energetic plasma sheet particles equatorward of the cusp (near the open-closed field line boundary weakened visibly and shifted equatorward, (3 the high-latitude aurora during the previous northward IMF, which is associated with lobe reconnection, persisted briefly (3 min and brightened, before it disappeared from the field-of-view, (4 the activation of a strong convection bay (DPY current at cusp and sub-cusp latitudes when the field turned strongly south, (5 a distinct wave motion of the plasma sheet outer boundary, as inferred from the aurora, which correlates closely with Pc 5 magnetic pulsations. Our interpretation of the dramatic reconfiguration is that reconnection poleward of the cusp coexisted briefly with reconnection at sub-cusp latitudes. The latter provided a magnetic field connection which enabled, on the one hand, magnetosheath particles to enter and cause the red-line cusp aurora, and on the other hand, allowed for magnetospheric energetic particles to escape and weaken the outer plasma sheet source of the green-line emission. The coexistence of the two cusp auroras reflects the time required for one field line topology to replace another, which, under the prevailing high speed wind ( ~ 650 km/s, lasts ~ 3–4 min. The motion of open flux tubes propagating from equator to pole during this transition is traced in the aurora by a poleward moving form. The waves on the outer boundary of the plasma sheet are most likely due to the Kelvin-Helmholtz instability. The study illustrates the ability of local auroral observations to monitor even a global change in

  2. Effect of the interaction among traps on the shape of thermoluminescence glow curves

    Energy Technology Data Exchange (ETDEWEB)

    Marcazzo, J. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Rivadavia 1917, 1033 Buenos Aires (Argentina); Santiago, M. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina) and Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Rivadavia 1917, 1033 Buenos Aires (Argentina)]. E-mail: msantiag@exa.unicen.edu.ar; Spano, F. [Autoridad Regulatoria Nuclear, Av. del Libertador 8250, 1429 Buenos Aires (Argentina); Lester, M. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Rivadavia 1917, 1033 Buenos Aires (Argentina); Ortega, F. [Facultad de Ingenieria, Universidad Nacional del Centro de la Provincia de Buenos Aires, Av. del Valle 5737, 7400 Olavarria (Argentina); Molina, P. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Rivadavia 1917, 1033 Buenos Aires (Argentina); Caselli, E. [IFAS, Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), calle 526 entre 10 y 11, 1900 La Plata (Argentina)

    2007-09-15

    The effect of the interaction among traps on the structure of thermoluminescence glow curves has been investigated by generating numerically simulated glow curves for a wide range of trap parameters. The results reported in this paper provide useful insights which assist in the analysis of experimental glow curves. The most important result shows that it is incorrect to assume beforehand that each peak is related to a specific trapping state. The validity of the quasiequilibrium approximation is briefly discussed.

  3. Phosphorylation of microtubule-binding protein Hec1 by mitotic kinase Aurora B specifies spindle checkpoint kinase Mps1 signaling at the kinetochore.

    Science.gov (United States)

    Zhu, Tongge; Dou, Zhen; Qin, Bo; Jin, Changjiang; Wang, Xinghui; Xu, Leilei; Wang, Zhaoyang; Zhu, Lijuan; Liu, Fusheng; Gao, Xinjiao; Ke, Yuwen; Wang, Zhiyong; Aikhionbare, Felix; Fu, Chuanhai; Ding, Xia; Yao, Xuebiao

    2013-12-13

    The spindle assembly checkpoint (SAC) is a quality control device to ensure accurate chromosome attachment to spindle microtubule for equal segregation of sister chromatid. Aurora B is essential for SAC function by sensing chromosome bi-orientation via spatial regulation of kinetochore substrates. However, it has remained elusive as to how Aurora B couples kinetochore-microtubule attachment to SAC signaling. Here, we show that Hec1 interacts with Mps1 and specifies its kinetochore localization via its calponin homology (CH) domain and N-terminal 80 amino acids. Interestingly, phosphorylation of the Hec1 by Aurora B weakens its interaction with microtubules but promotes Hec1 binding to Mps1. Significantly, the temporal regulation of Hec1 phosphorylation orchestrates kinetochore-microtubule attachment and Mps1 loading to the kinetochore. Persistent expression of phosphomimetic Hec1 mutant induces a hyperactivation of SAC, suggesting that phosphorylation-elicited Hec1 conformational change is used as a switch to orchestrate SAC activation to concurrent destabilization of aberrant kinetochore attachment. Taken together, these results define a novel role for Aurora B-Hec1-Mps1 signaling axis in governing accurate chromosome segregation in mitosis.

  4. NITROGEN POTENTIAL DURING ION NITRIDING PROCESS IN GLOW-DISCHARGE PLASMA

    Directory of Open Access Journals (Sweden)

    A. A. Kozlov

    2015-01-01

    Full Text Available The paper considers problems on regulation of phase composition of a nitrided layer during gas and ion nitriding process in a glow-discharge. It has been established that  available models for control of nitrided layer structure with the help of nitriding index (nitrogen potential can not be applied for nitriding process in the glow-discharge. Principal difference of the ion nitriding from the gas one is in the fact that chemically active nitrogen is formed in the discharge zone (cathode layer and its mass-transfer is carried out in the form of an active particle flow (ions, atoms, molecules which directed to the metal surface.Interrelation of chemical discharge activity with such characteristics of nitriding steel as nitrogen solubility in  α-solid solution and  coefficient diffusion during ion nitriding in low-discharge plasma. It has been shown that regulation of the nitride layer structure during ion nitriding is reached due to changes in nitrogen flow density in plasma. While supporting the flow at the level of nitrogen solubility in  one phase or another (α, γ′  it is possible to obtain the nitrided layer consisting only of α-solid solution or γ′-nitride layer and diffusion sub-layer. Moreover a specific range of nitrogen flow density values exists for every steel grade where it is possible to ensure a limiting nitrogen concentration in α-solid solution and the γ′-layer characterized by low diffusion  mobility is not formed on the surface.

  5. A glow curve analyzer (GCA) for routine analysis of personnel thermoluminescent dosemeter results

    Energy Technology Data Exchange (ETDEWEB)

    Chase, W.J. [Health Physics Department, Ontario Power Generation, Whitby, Ont. (Canada)], E-mail: john.chase@opg.com; Bezaire, M.D. [Department of Applied Health Sciences, University of Waterloo, Waterloo, Ont. (Canada); Vanderzwet, F.P. [Bruce Power, P.O. Box 1540, Building B13, Tiverton, Ont., N0G 2T0 (Canada); Taylor, C.E. [Health Physics Department, Ontario Power Generation, Whitby, Ont. (Canada)

    2008-02-15

    A glow curve analyzer (GCA) spreadsheet has been developed using Microsoft Excel to perform glow curve analysis on thermoluminescent dosimeter (TLD) data from a personnel dosimetry system. The TLD data come from cards with four LiF:Mg,Ti chips that have been annealed and therefore have a simple glow peak structure. GCA removes spikes in the glow curve data, and then smoothes it. After select start and end points for the glow peak, it fits a Boltzmann function to represent the glow curve signal background under the glow peak. The Boltzmann function is subtracted and two Weibull curves are fit to the remaining net signal between the start and end points. The first Weibull curve is fit to peak 5, and the second one to any small remaining contribution from peaks 3 and 4 or from contaminants. The sum of the two Weibull curves is the glow curve signal result. GCA provides rapid review and correction of all glow curves, improving the quality of the results and reducing the time required for complete processing of official dose results.

  6. Means of introducing an analyte into liquid sampling atmospheric pressure glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Marcus, R. Kenneth; Quarles, Jr., Charles Derrick; Russo, Richard E.; Koppenaal, David W.; Barinaga, Charles J.; Carado, Anthony J.

    2017-01-03

    A liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device as well as systems that incorporate the device and methods for using the device and systems are described. The LS-APGD includes a hollow capillary for delivering an electrolyte solution to a glow discharge space. The device also includes a counter electrode in the form of a second hollow capillary that can deliver the analyte into the glow discharge space. A voltage across the electrolyte solution and the counter electrode creates the microplasma within the glow discharge space that interacts with the analyte to move it to a higher energy state (vaporization, excitation, and/or ionization of the analyte).

  7. Detection of negative ions in glow discharge mass spectrometry for analysis of solid specimens

    DEFF Research Database (Denmark)

    Canulescu, Stela; Molchan, Igor S.; Tauziede, C.

    2010-01-01

    A new method is presented for elemental and molecular analysis of halogen-containing samples by glow discharge time-of-flight mass spectrometry, consisting of detection of negative ions from a pulsed RF glow discharge in argon. Analyte signals are mainly extracted from the afterglow regime...... be used to study the distribution of a tantalum fluoride layer within the anodized tantala layer. Further, comparison is made with data obtained using glow-discharge optical emission spectroscopy, where elemental fluorine can only be detected using a neon plasma. The ionization mechanisms responsible...... for the formation of negative ions in glow discharge time-of-flight mass spectrometry are briefly discussed....

  8. Glow curves and the emission of flux grown BaFCl:Gd crystals

    Energy Technology Data Exchange (ETDEWEB)

    Somaiah, K.; Hari Babu, V. (Osmania Univ., Hyderabad (India). Dept. of Physics)

    1984-03-16

    Thermoluminescence output of the BaFCl is found to be enhanced enormously when it is doped with gadolinium. An incorporation of gadolinium in BaFCl produces additional glow peaks at 455 and 560 K, an optical absorption band at 660 nm, and glow emission bands at 315 and 450 nm. The 315 nm emission band is the characteristic emission of the gadolinium impurity. Since similar emission spectra are obtained for different glow peaks, they are attributed to the luminescent centers caused by the gadolinium impurity in the lattice. The trap depth and frequency factor of additional glow peaks are calculated employing different methods.

  9. The grand aurorae borealis seen in Colombia in 1859

    Science.gov (United States)

    Moreno Cárdenas, Freddy; Cristancho Sánchez, Sergio; Vargas Domínguez, Santiago

    2016-01-01

    On Thursday, September 1, 1859, the British astronomer Richard Carrington, for the first time ever, observes a spectacular gleam of visible light on the surface of the solar disk, the photosphere. The Carrington Event, as it is nowadays known by scientists, occurred because of the high solar activity that had visible consequences on Earth, in particular reports of outstanding aurorae activity that amazed thousands of people in the western hemisphere during the dawn of September 2. The geomagnetic storm, generated by the solar-terrestrial event, had such a magnitude that the auroral oval expanded towards the equator, allowing low latitudes, like Panama's 9°N, to catch a sight of the aurorae. An expedition was carried out to review several historical reports and books from the northern cities of Colombia allowed the identification of a narrative from Montería, Colombia (8° 45‧N), that describes phenomena resembling those of an aurorae borealis, such as fire-like lights, blazing and dazzling glares, and the appearance of an immense S-like shape in the sky. The very low latitude of the geomagnetic north pole in 1859, the lowest value in over half a millennia, is proposed to have allowed the observations of auroral events at locations closer to the equator, and supports the historical description found in Colombia. The finding of such chronicle represents one of the most complete descriptions of low-latitude sightings of aurorae caused by the Carrington Event.

  10. Astronaut Scott Carpenter inserted into Aurora 7 spacecraft

    Science.gov (United States)

    1962-01-01

    Astronaut M. Scott Carpenter, pilot of the Mercury-Atlas 7 space flight, is inserted into Aurora 7 spacecraft during the prelaunch countdown. Carpenter is assisted into the spacecraft by Astronaut John Glenn and Gunter Vendt, McDonnell Douglas pad capsule test conducter.

  11. The WW-HECT protein Smurf2 interacts with the Docking Protein NEDD9/HEF1 for Aurora A activation

    Directory of Open Access Journals (Sweden)

    Moore Finola E

    2010-09-01

    Full Text Available Abstract The multi-functional adaptor protein NEDD9/HEF1/Cas-L regulates cell motility, invasion and cell cycle progression, and plays key roles in cancer progression and metastasis. NEDD9 is localized to the centrosome and is required for activation of Aurora A kinase in mitosis. Here we demonstrate that the HECT-WW protein Smurf2 physically associates with NEDD9 and is required for the stability of NEDD9 protein. Smurf2 depletion results in a marked decrease in NEDD9 protein levels, by facilitating polyubiquitination and proteasomal degradation of NEDD9. Conversely, forced overexpression of Smurf2 results in upregulation of endogenous NEDD9 protein, confirming the role for Smurf2 in NEDD9 stability. Cells with Smurf2 depletion fail to activate Aurora A at the G2/M boundary, leading to a marked delay in mitotic entry. These observations suggest that the stable complex of Smurf2 and NEDD9 is required for timely entry into mitosis via Aurora A activation.

  12. Aurora kinases as druggable targets in pediatric leukemia: heterogeneity in target modulation activities and cytotoxicity by diverse novel therapeutic agents.

    Directory of Open Access Journals (Sweden)

    Aarthi Jayanthan

    Full Text Available Leukemia is the most common pediatric malignancy, constituting more than 30% of all childhood cancers. Although cure rates have improved greatly, approximately one in five children relapse and poor survival rates post relapse remain a challenge. Given this, more effective and innovative therapeutic strategies are needed in order to improve prognosis. Aurora kinases, a family of serine/threonine kinases essential for the regulation of several mitotic processes, have been identified as potential targets for cancer therapeutics. Elevated expression of Aurora kinases has been demonstrated in several malignancies and is associated with aberrant mitotic activity, aneuploidy and alterations in chromosomal structure and genome instability. Based on this rationale, a number of small molecule inhibitors have been formulated and advanced to human studies in the recent past. A comparative analysis of these agents in cytotoxicity and target modulation analyses against a panel of leukemia cells provides novel insights into the unique mechanisms and codependent activity pathways involved in targeting Aurora kinases, constituting a distinctive preclinical experimental framework to identify appropriate agents and combinations in future clinical studies.

  13. New auroras on the roles of the Chromosomal Passenger Complex in cytokinesis: implications for cancer therapies

    Directory of Open Access Journals (Sweden)

    Pier Paolo eD'Avino

    2015-10-01

    Full Text Available The Chromosomal Passenger Complex (CPC, composed of a kinase component, Aurora B, the scaffolding subunit Inner Centromeric Protein (INCENP, Borealin, and Survivin, is a key regulator of cell division. It controls multiple events, from chromosome condensation in prophase to the final separation or abscission of the two daughter cells. The essential functions of the CPC during metaphase, however, have always hindered an accurate study of its role during cytokinesis. The recent development of small molecule inhibitors against Aurora B and the use of elegant technologies such as chemical genetics have offered new approaches to study the functions of the CPC at the end of cell division. Here we review the recent findings about the roles of the CPC in controlling the assembly of the cleavage furrow, central spindle and midbody. We will also discuss the crucial function of this complex in controlling abscission timing in order to prevent abscission when lagging chromatin is present at the cleavage site, thereby avoiding the formation of genetically abnormal daughter cells. Finally, we offer our perspective on how to exploit the potential therapeutic applications of inhibiting CPC activity during cytokinesis in cancer cells.

  14. v-Src causes delocalization of Mklp1, Aurora B, and INCENP from the spindle midzone during cytokinesis failure

    Energy Technology Data Exchange (ETDEWEB)

    Soeda, Shuhei [Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675 (Japan); Nakayama, Yuji, E-mail: nakayama@mb.kyoto-phu.ac.jp [Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675 (Japan); Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414 (Japan); Honda, Takuya; Aoki, Azumi; Tamura, Naoki; Abe, Kohei; Fukumoto, Yasunori [Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675 (Japan); Yamaguchi, Naoto, E-mail: nyama@faculty.chiba-u.jp [Department of Molecular Cell Biology, Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba 260-8675 (Japan)

    2013-06-10

    Src-family tyrosine kinases are aberrantly activated in cancers, and this activation is associated with malignant tumor progression. v-Src, encoded by the v-src transforming gene of the Rous sarcoma virus, is a mutant variant of the cellular proto-oncogene c-Src. Although investigations with temperature sensitive mutants of v-Src have shown that v-Src induces many oncogenic processes, the effects on cell division are unknown. Here, we show that v-Src inhibits cellular proliferation of HCT116, HeLa S3 and NIH3T3 cells. Flow cytometry analysis indicated that inducible expression of v-Src results in an accumulation of 4N cells. Time-lapse analysis revealed that binucleation is induced through the inhibition of cytokinesis, a final step of cell division. The localization of Mklp1, which is essential for cytokinesis, to the spindle midzone is inhibited in v-Src-expressing cells. Intriguingly, Aurora B, which regulates Mklp1 localization at the midzone, is delocalized from the spindle midzone and the midbody but not from the metaphase chromosomes upon v-Src expression. Mklp2, which is responsible for the relocation of Aurora B from the metaphase chromosomes to the spindle midzone, is also lost from the spindle midzone. These results suggest that v-Src inhibits cytokinesis through the delocalization of Mklp1 and Aurora B from the spindle midzone, resulting in binucleation. -- Highlights: • v-Src inhibits cell proliferation of HCT116, HeLa S3 and NIH3T3 cells. • v-Src induces binucleation together with cytokinesis failure. • v-Src causes delocalization of Mklp1, Aurora B and INCENP from the spindle midzone.

  15. Large Scale Modelling of Glow Discharges or Non - Plasmas

    Science.gov (United States)

    Shankar, Sadasivan

    The Electron Velocity Distribution Function (EVDF) in the cathode fall of a DC helium glow discharge was evaluated from a numerical solution of the Boltzmann Transport Equation(BTE). The numerical technique was based on a Petrov-Galerkin technique and a unique combination of streamline upwinding with self -consistent feedback-based shock-capturing. EVDF for the cathode fall was solved at 1 Torr, as a function of position x, axial velocity v_{rm x}, radial velocity v_{rm r}, and time t. The electron-neutral collisions consisted of elastic, excitation, and ionization processes. The algorithm was optimized and vectorized to speed execution by more than a factor of 10 on CRAY-XMP. Efficient storage schemes were used to save the memory allocation required by the algorithm. The analysis of the solution of BTE was done in terms of the 8-moments that were evaluated. Higher moments were found necessary to study the momentum and energy fluxes. The time and length scales were estimated and used as a basis for the characterization of DC glow discharges. Based on an exhaustive study of Knudsen numbers, it was observed that the electrons in the cathode fall were in the transition or Boltzmann regime. The shortest relaxation time was the momentum relaxation and the longest times were the ionization and energy relaxation times. The other times in the processes were that for plasma reaction, diffusion, convection, transit, entropy relaxation, and that for mean free flight between the collisions. Different models were classified based on the moments, time scales, and length scales in their applicability to glow discharges. These consisted of BTE with different number af phase and configuration dimensions, Bhatnagar-Gross-Krook equation, moment equations (e.g. Drift-Diffusion, Drift-Diffusion-Inertia), and spherical harmonic expansions.

  16. Glow Discharge Plasma Nitriding of AISI 304 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    A.QAYYUM; M.A.NAVEED; S.ZEB; G.MURTAZA; M.ZAKAULLAH

    2007-01-01

    Glow discharge plasma nitriding of AISI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis.The treated samples were analysed by X-ray diffraction(XRD)to explore the changes induced in the crystallographic structure.The XRD pattern confirmed the formation of an expanded austenite phase(γN)owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice.A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth(μm).The results showed clear evidence of surface changes with substantial increase in surface hardness.

  17. Ca2+ sparks and Ca2+ glows in superior cervical ganglion neurons

    Institute of Scientific and Technical Information of China (English)

    Li-jun YAO; Cai-hong WU; Jie LIU; Zhuan ZHOU; He-ping CHENG; Gang WANG; Kun-fu OU-YANG; Chao-liang WEI; Xian-hua WANG; Shi-rong WANG; Wei YAO; Hong-ping HUANG; Jian-hong LUO

    2006-01-01

    Aim: Ca2+ release from the endoplasmic reticulum (ER) is an integral component of neuronal Ca2+ signaling. The present study is to investigate properties of local Ca2+ release events in superior cervical ganglion (SCO) neurons. Methods: Primary cultured SCO neurons were prepared from neonatal rats (P3-P7). Low concentration of caffeine was used to induce Ca2+ release from the ER Ca2+ store, and intracellular Ca2+ was recorded by high-resolution line scan confocal imaging and the Ca2+ indicator Fluo-4. Results: Two populations of local Ca2+ release events with distinct temporal characteristics were evoked by 1.5 mmol/L caffeine near the surface membrane in the soma and the neurites of SCG neurons. Brief events similar to classic Ca2+ sparks lasted a few hundreds of milliseconds, whereas long-lasting events displayed duration up to tens of seconds. Typical somatic and neurite sparks were of 0.3- and 0.52-fold increase in local Fluo-4 fluorescence, respectively. Typical Ca2+ glows were brighter (△F/F0 approximately 0.6), but were highly confined in space. The half maximum of full duration of neurite sparks was much longer than those in the soma (685 vs 381 ms). Conclusion: Co-existence of Ca2+ sparks and Ca2+ glows in SCG neurons indicates distinctive local regulation of Ca2+ release kinetics. The local Ca2+ signals of variable, site-specific temporal length may bear important implications in encoding a "memory" of the trigger signal.

  18. Elevated Aurora B expression contributes to chemoresistance and poor prognosis in breast cancer.

    Science.gov (United States)

    Zhang, Yiqian; Jiang, Chunling; Li, Huilan; Lv, Feng; Li, Xiaoyan; Qian, Xiaolong; Fu, Li; Xu, Bo; Guo, Xiaojing

    2015-01-01

    Aurora-B is a major kinase responsible for appropriate mitotic progression. Elevated expression of Aurora-B has been frequently associated with several types of cancer, including breast cancer. However, it is not clear whether the alteration contributes to tumor responses to therapies and prognosis. In this study, we conducted immunohistochemistry using antibodies against Aurora-B, S1981p-ATM, Ki67, and p53 in paraffin-embedded tumor tissues from 312 invasive breast cancer patients. The correlation between disease-free-survival (DFS) and Aurora-B expression was analyzed using the Kaplan-Meier method and log-rank test. A Cox proportional hazards regression analysis was used to determine whether Aurora-B was an independent prognostic factor for breast cancer. We found that Aurora-B expression was correlated with the proliferation index (P breast cancer tissues. Further we found that Aurora-B expression was associated with lymph node metastasis (P = 0.002) and histological grade (P = 0.001). Multivariate analyses indicated that elevated Aurora-B expression predicted a poor survival. In a subgroup of patients that received neoadjuvant chemotherapy, we found that elevated Aurora-B contributed to chemoresistance (P = 0.011). In conclusion, elevated Aurora-B expression in breast cancer patients contributes to chemoresistance and predicts poor prognosis.

  19. Cold starting of fluorescent lamps - part II: experiments on glow times and electrode damaging

    Science.gov (United States)

    Langer, Reinhard; Paul, Irina; Hilscher, Achim; Horn, Siegfried; Tidecks, Reinhard

    2017-01-01

    In the present work we present experiments on cold start and the resulting electrode damaging (reducing lamp life) of AC driven fluorescent lamps. The crucial parameter is the glow time, determined from time resolved measurements of lamp voltage and current. The relation between the energy consumed during glow phase and the glow time is studied. It turns out that there is no common threshold of energy until the glow-to-arc transition takes place, but strong energy input into the lamp yields short glow times. The transient behaviour from the glow to the arc regime is investigated and the stable operation points of the arc discharge are determined, yielding an arc discharge voltage-current characteristics of the lamp type investigated. The electrode damage is investigated as a function of the open source voltage and the ballast resistance. Subsequent cold starts lead to an increase of the glow time due to electrode damaging, i.e., the electrode damage accumulates. Different regeneration procedures and their effectiveness are compared. Regeneration burning turns out to be more effective than heating up the electrode. A criterion for avoiding high electrode damage is obtained, indicating that the average power during glow time should exceed 20 W.

  20. Glow experiment documentation of OMS/RCS pods and vertical stabilizer

    Science.gov (United States)

    1982-01-01

    Glow experiment documentation of orbital maneuvering system (OMS) reaction control system (RCS) pods and vertical stabilizer shows chemoluminescent effect resulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. Image intensifier on NIKON 35mm camera used to record glow on vertical tail and OMS pods.

  1. Glow experiment documentation of OMS/RCS pod and vertical stabilizer

    Science.gov (United States)

    1982-01-01

    Glow experiment documentation of one of the orbital maneuvering system (OMS) reaction control system (RCS) pods and a portion of the vertical stabilizer shows chemoluminescent effectresulting from atomic oxygen impacting the spacecraft and building to the point that the atomic oxygen atoms combine to form molecules of oxygen. The Image Intensifier on NIKON 35mm camera was used to record the glow.

  2. Assessing the Warm Glow Effect in Contingent Valuations for Public Libraries

    Science.gov (United States)

    Lee, Soon-Jae; Chung, Hye-Kyung; Jung, Eun-Joo

    2010-01-01

    This article aims to present evidence of the warm glow effect in a public library setting. More specifically, it tests whether individual respondents with different values for the warm glow component report different values for their willingness to pay (WTP). The data come from a contingent valuation survey conducted on randomly selected citizens…

  3. A Review on Chemical Effects in Aqueous Solution induced by Plasma with Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Chemical effects in different aqueous solutions induced by plasma with glow dis charge electrolysis (GDE) and contact glow discharge electrolysis (CGDE) are described in this paper. The experimental and discharge characteristics are also reviewed. These are followed by a discussion of their mechanisms of both anodic and cathodic CGDE..

  4. Numerical analysis of thermoluminescence glow curves; Analisis numerico de las cruvas de termoluminiscencia

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Ros, J. M.; Delgado, A.

    1989-07-01

    This report presents a method for the numerical analysis of complex thermoluminescence glow curves resolving the individual glow peak components. The method employs first order kinetics analytical expressions and is based In a Marquart-Levenberg minimization procedure. A simplified version of this method for thermoluminescence dosimetry (TLD) is also described and specifically developed to operate whit Lithium Fluoride TLD-100. (Author). 36 refs.

  5. Application of computerized glow curve deconvolution to determine the spectroscopy of traps in colorless microcline

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, B. Arunkumar [Department of Radiotherapy, RIMS, Lamphel, Imphal 795004, Manipur (India)], E-mail: arunsb2000@yahoo.co.uk; Singh, A. Nabachandra [Department of Physics, Thoubal College, Thoubal 795138, Manipur (India); Singh, S. Nabadwip [Department of Physics, Kumbi College, Kumbi 795133, Manipur (India); Singh, O. Binoykumar [Department of Physics, Y.K. College, Wangjing 795148, Manipur (India)

    2009-01-15

    Kinetic parameters of glow peaks (as many as 14 in the range of 75-575 deg. C) of colorless microcline have been successfully achieved to a high degree of certainty by resorting to computerized glow curve deconvolution (CGCD) in the framework of kinetics formalism. The second derivative plot of the experimental glow curve is used to locate the hidden glow peaks. The criteria to accept the goodness of fit between the experimental glow curve and the numerically generated best fit curve is judged by statistical test namely, {chi}{sup 2}-test. As a cross check, figure of merit (FOM) is also evaluated. The kinetic parameters of the higher temperature trap electrons of colorless microcline are determined by using lower heating rates.

  6. Research on the Plasma Anemometer Based on AC Glow Discharge

    Directory of Open Access Journals (Sweden)

    Bing Yu

    2017-01-01

    Full Text Available A new plasma anemometer based on AC glow discharge is designed in this article. Firstly, theoretical analysis of plasma anemometer working principle is introduced to prove the feasibility of the experimental measurement method. Then the experiments are carried out to study the effects of different parameters on the static discharge characteristics of the plasma anemometer system, by which the system optimization methods are obtained. Finally, several groups of appropriate parameters are selected to build the plasma anemometer system based on resistance capacitance coupling negative feedback AC glow discharge, and different airflow speeds are applied to obtain the achievable velocity measurement range. The results show that there is a linear relationship between airflow velocity and discharge current in an allowable error range, which can be applied for airflow velocity measurement. Negative feedback coupling module, which is composed of the coupling resistance and the coupling capacitance, has good effects on improving the system stability. The measurement range of the airflow velocity is significantly increased when the electrode gap is 3 mm, coupling resistance is 470 Ω, and coupling capacitance is 220 pF.

  7. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ping-ze; XU Zhong; HE Zhi-yong; ZHANG Gao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6Al-4V and Ti-6.5Al-0.3Mo-l.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%.Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  8. Double Glow Plasma Surface Alloyed Burn-resistant Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    ZHANGPing-ze; XUZhong; HEZhi-yong; ZHANGGao-hui

    2004-01-01

    Conventional titanium alloy may be ignited and burnt under high temperature, high pressure and high gas flow velocity condition. In order to avoid this problem, we have developed a new kind of burn-resistant titanium alloy-double glow plasma surface alloying burn-resistant titanium alloy. Alloying element Cr, Mo, Cu are induced into the Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si substrates according to double glow discharge phenomenon, Ti-Cr ,Ti-Mo, Ti-Cu binary burn-resistant alloy layers are formed on the surface of Ti-6A1-4V and Ti-6.5Al-0.3Mo-1.5Zr-0.25Si alloys. The depth of the surface burn-resistant alloy layer can reach to above 200 microns and alloying element concentration can reach 90%. Burn-resistant property experiments reveal that if Cr concentration reach to 14%, Cu concentration reach to 12%, Mo concentration reach to 10% in the alloying layers, ignition and burn of titanium alloy can be effectively avoided.

  9. COMPOSITION AND STRUCTURAL STUDIES OF STRONG GLOW DISCHARGE POLYMER COATINGS

    Energy Technology Data Exchange (ETDEWEB)

    CZECHOWICZ, DG; CASTILLO, ER; NIKROO, A

    2002-04-01

    OAK A271 COMPOSITION AND STRUCTURAL STUDIES OF STRONG GLOW DISCHARGE POLYMER COATINGS. An investigation of the chemical composition and structure of strong glow discharge (GDP) polymer shells made for cryogenic experiments at OMEGA is described. The investigation was carried out using combustion and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The strongest coatings were observed to have the lowest hydrogen content or hydrogen/carbon H/C ratio, whereas the weakest coatings had the highest hydrogen content or H/C ratio. Chemical composition results from combustion were used to complement FTIR analysis to determine the relative hydrogen content of as-fabricated coatings. Good agreement was observed between composition results obtained from combustion and FTIR analysis. FTIR analysis of coating structures showed the strongest coatings to have less terminal methyl groups and a more double bond or olefinic structure. Strong GDP coatings that were aged in air react more with oxygen and moisture than standard GDP coatings. In addition to a more olefinic structure, there may also be more free-radial sites present in strong GDP coatings, which leads to greater oxygen uptake.

  10. Multiple solutions in the theory of dc glow discharges

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, P G C; Benilov, M S; Faria, M J [Departamento de Fisica, Universidade da Madeira, Largo do Municipio, 9000 Funchal (Portugal)

    2010-04-15

    Multiple steady-state solutions existing in the theory of dc glow discharges are computed for the first time. The simulations are performed in 2D in the framework of the simplest self-consistent model, which accounts for a single ion species and employs the drift-diffusion approximation. Solutions describing up to nine different modes were found in the case where losses of the ions and the electrons due to diffusion to the wall were neglected. One mode is 1D, exists at all values of the discharge current, and represents in essence the well-known solution of von Engel and Steenbeck. The other eight modes are axially symmetric, exist in limited ranges of the discharge current, and are associated with different patterns of current spots on the cathode. The mode with a spot at the centre of the cathode exhibits a well pronounced effect of normal current density. Account of diffusion losses affects the solutions dramatically: the number of solutions is reduced, a mode appears that exists at all discharge currents and comprises the Townsend, subnormal, normal and abnormal discharges. The solutions that exist in limited current ranges describe patterns, and these patterns seem to represent axially symmetric analogues of the 3D patterns observed in dc glow microdischarges in xenon.

  11. Aurorasaurus: A citizen science platform for viewing and reporting the aurora

    Science.gov (United States)

    MacDonald, E. A.; Case, N. A.; Clayton, J. H.; Hall, M. K.; Heavner, M.; Lalone, N.; Patel, K. G.; Tapia, A.

    2015-09-01

    A new, citizen science-based, aurora observing and reporting platform has been developed with the primary aim of collecting auroral observations made by the general public to further improve the modeling of the aurora. In addition, the real-time ability of this platform facilitates the combination of citizen science observations with auroral oval models to improve auroral visibility nowcasting. Aurorasaurus provides easily understandable aurora information, basic gamification, and real-time location-based notification of verified aurora activity to engage citizen scientists. The Aurorasaurus project is one of only a handful of space weather citizen science projects and can provide useful results for the space weather and citizen science communities. Early results are promising with over 2000 registered users submitting over 1000 aurora observations and verifying over 1700 aurora sightings posted on Twitter.

  12. Jadomycin B, an Aurora-B kinase inhibitor discovered through virtual screening

    Institute of Scientific and Technical Information of China (English)

    Da Huafu; Jing Zhang; Jian Tingzheng; Yan Li; Ke Qianyang; Yan Changwang; Shu Yisi

    2008-01-01

    @@ Aurora kinases are clearly implicated in tumorgenesis and have emerged as promising targets for cancer therapy in recent years. In a virtual screening attempt, 22 compounds were identified from nearly 15,000 microbial natural products as potential small-molecule inhibitors of human Aurora-B kinase. When tested in yeast models, 2 compounds (one is Jadomycin B) showed preferential inhibition of ipll-321 (yeast Aurora kinase temperature sensitive mutant) than wild type yeast cell, suggesting these compounds are true Aurora kinase inhibitors. Further in vitro biochemical assay using purified recombinant Aurora-B kinase showed Jadomycin B inhibits Aurora-B activity in a dose-dependent fashion while two Jadomycin congeners, Jadomycin S and T, showed no activity.

  13. Aurorae. Firework in the sky. 2. upd. ed.; Polarlichter. Feuerwerk am Himmel

    Energy Technology Data Exchange (ETDEWEB)

    Pfoser, Andreas; Eklund, Tom

    2013-07-01

    Aurorae are fascinating phenomena. As aurora borealis and aurora australis occurring in the polar regions of both earth hemispheres, their incessant color and shape games put people in wonder. The meteorologist Andreas Pfoser explains the physical connections, which lead to the formation of this natural phenomenon. The link with the activity of the sun and the interaction in the earth atmosphere are explained detailedly and understandably. The fantastic recordings, presented in generous horizontal format has collected the Finnish aurora photographer Tom Eklund over a period of time of 14 years. Thereby it succeeded, to document also some events, the origin of which on our daystar were recorded by solar satellites, so that the sequence of events from the solar eruption until the aurora spectacle can be reproduced. The present 2nd edition contains new scientific findings. Additionally numerous aurora pictures were replaced by more actual photos created with modern technology.

  14. Using the Aurora to Remote Sense Near-Earth Space

    Science.gov (United States)

    Donovan, Eric

    2012-10-01

    The Earth's magnetosphere is formed by the interaction of the solar wind and Earth's magnetic field. Sitting like a giant wind sock in the solar wind, the magnetosphere is an enormous and dynamic region. The processes at work within the magnetosphere serve as exemplars of phenomena that happen throughout the cosmos, and have consequences in the upper atmosphere. One of those is the aurora, a truly global and multi-scale phenomenon that we are only beginning to understand. Of all the countries on Earth, Canada has the largest region of land under the auroral zone, something Canadian scientists have capitalized on for more than fifty years. In this talk, I will outline how we use observations of the aurora to remote sense the magnetosphere, focusing on Canadian ground-based and space-based programs that provide remarkable images of this beautiful natural phenomenon.

  15. Planetary protection in the framework of the Aurora exploration program

    Science.gov (United States)

    Kminek, G.

    The Aurora Exploration Program will give ESA new responsibilities in the field of planetary protection. Until now, ESA had only limited exposure to planetary protection from its own missions. With the proposed ExoMars and MSR missions, however, ESA will enter the realm of the highest planetary protection categories. As a consequence, the Aurora Exploration Program has initiated a number of activities in the field of planetary protection. The first and most important step was to establish a Planetary Protection Working Group (PPWG) that is advising the Exploration Program Advisory Committee (EPAC) on all matters concerning planetary protection. The main task of the PPWG is to provide recommendations regarding: Planetary protection for robotic missions to Mars; Planetary protection for a potential human mission to Mars; Review/evaluate standards & procedures for planetary protection; Identify research needs in the field of planetary protection. As a result of the PPWG deliberations, a number of activities have been initiated: Evaluation of the Microbial Diversity in SC Facilities; Working paper on legal issues of planetary protection and astrobiology; Feasibility study on a Mars Sample Return Containment Facility; Research activities on sterilization procedures; Training course on planetary protection (May, 2004); Workshop on sterilization techniques (fall 2004). In parallel to the PPWG, the Aurora Exploration Program has established an Ethical Working Group (EWG). This working group will address ethical issues related to astrobiology, planetary protection, and manned interplanetary missions. The recommendations of the working groups and the results of the R&D activities form the basis for defining planetary protection specification for Aurora mission studies, and for proposing modification and new inputs to the COSPAR planetary protection policy. Close cooperation and free exchange of relevant information with the NASA planetary protection program is strongly

  16. "Making Sense of the Aurora: A Research Project"

    OpenAIRE

    Robert Marc Friedman

    2012-01-01

    The article provides an introduction to a on-going research project based at University of Tromsø that seeks to analyze the history of efforts to make sense of the aurora borealis from the early 1700s through to the Cold War. Following brilliant displays of the northern lights in the early eighteenth century, natural philosophers strove to explain this phenomenon that evoked widespread fear and superstition. It was not until well into the twentieth century that consensual explanation emerged ...

  17. Environmental Baseline Survey, Fitzsimmons Army Medical Center, Aurora, Colorado. Volume II - Appendices A-G.

    Science.gov (United States)

    1996-05-01

    QUENTIN ST 128 F104 80011 1.28 NNW FINDS C00000710681 ALPHA MFG 3250 QUENTIN ST STE 136 F105 80011 1.28 NNW FINDS m 0000902 CHIPS DISTRIBUTING 2290...COD100711514 CRAWFORD ELEMENTARY SCHOOL 1600 FLORENCE ST AURORA 3 80010 COD149382491 DAISY FABRICARE CENTER 9677 MONTVIEW BLVD AURORA 3 80010 C00000077180... FABRICARE CTR 1,3 9677 MONTVIEW BLVD AURORA 80010 COD149382491 ALKE’S LAUNDRY & DRY CLEANING INC. 1,3 8935 E COLFAX AVE AURORA 80010 CO0000077180 DD

  18. Earliest Datable Records of Aurora-like Phenomena in the Astronomical Diaries from Babylonia

    CERN Document Server

    Hayakawa, Hisashi; Ebihara, Yusuke; Kawamura, Akito Davis; Miyahara, Hiroko; Tamazawa, Harufumi; Isobe, Hiroaki

    2016-01-01

    The Astronomical Diaries from Babylonia (ADB) are an excellent source of information of natural phenomena, including astronomical ones, in pre-Christ era because it contains the record of highly continuous and systematic observations. In this article we present results of a survey of aurora-like phenomena in ADB, spanning from BCE 652 to BCE 61. We have found 9 records of aurora-like phenomena. Philological and scientific examinations suggest 5 of them can be considered as likely candidate for aurora observations. They provide unique information about the solar and aurora activities in the first millennium BCE.

  19. Ancient writings reveal presence of aurora in 13th-century Canadian Arctic

    Science.gov (United States)

    Silverman, Sam

    Modern Norway, Iceland, and Greenland are subject to frequent displays of the aurora borealis. The aurora can be viewed on almost every clear night in the northern part of Iceland and southern Greenland, which lie in or near the auroral oval. Thus, it is surprising to find almost no mention of the aurora in medieval Norse chronicles or in the extensive Icelandic saga literature. Only one paragraph, in the "King's Mirror," a Norwegian writing dating to about 1250 C.E., notes the occurrence of the aurora in Greenland. The author reports this as hearsay and not from personal knowledge. For a fuller discussion of the Norse literature, see Brekke and Egeland [1983].

  20. Essential Roles of mTOR/Akt Pathway in Aurora-A Cell Transformation

    Directory of Open Access Journals (Sweden)

    Makoto Taga, Eiji Hirooka, Toru Ouchi

    2009-01-01

    Full Text Available We have recently demonstrated that Aurora-A kinase is a potential oncogene to develop mammary gland tumors in mice, when expressed under MMTV promoter. These tumors contain phosphorylated forms of Akt and mTOR, suggesting that Akt-mTOR pathway is involved in transformed phenotype induced by Aurora-A. In the present studies, we discovered that stable cell lines expressing Aurora-A contain phosphorylation of Akt Ser473 after prolonged passages of cell culture, not in cells of the early period of cell culture. Levels of PTEN tumor suppressor are significantly reduced in these late passage cells at least in part due to increased poly ubiquitination of the protein. Akt-activated Aurora-A cells formed larger colonies in soft agar and are resistant to UV-induced apoptosis. Aurora-A inhibitor, VX-680, can cause cell death of Aurora-A cells in which Akt is not activated. siRNA-mediated depletion of mTOR in those cells resulted in decreased phosphorylation of Akt Ser473, suggesting that TORC2 complex phosphorylates Akt in Aurora-A cells. Treatment of late-passage Aurora-A cells with mTOR inhibitor reduced colony formation in soft agar. These results strongly suggest that commitment of cell transformation by Aurora-A is determined by at least co-activation of Akt/mTOR pathway.

  1. Is diffuse aurora driven from above or below?

    Science.gov (United States)

    Khazanov, G. V.; Sibeck, D. G.; Zesta, E.

    2017-01-01

    In the diffuse aurora, magnetospheric electrons, initially precipitated from the inner plasma sheet via wave-particle interaction processes, degrade in the atmosphere toward lower energies, and produce secondary electrons via impact ionization of the neutral atmosphere. These initially precipitating electrons of magnetospheric origin can also be additionally reflected back into the magnetosphere, leading to a series of multiple reflections by the two magnetically conjugate atmospheres that can greatly impact the initially precipitating flux at the upper ionospheric boundary (700-800 km). The resultant population of secondary and primary electrons cascades toward lower energies and escape back to the magnetosphere. Escaping upward electrons traveling from the ionosphere can be trapped in the magnetosphere, as they travel inside the loss cone, via Coulomb collisions with the cold plasma, or by interactions with various plasma waves. Even though this scenario is intuitively transparent, this magnetosphere-ionosphere coupling element is not considered in any of the existing diffuse aurora research. Nevertheless, as we demonstrate in this letter, this process has the potential to dramatically affect the formation of electron precipitated fluxes in the regions of diffuse auroras.

  2. Meso-scale aurora within the expansion phase bulge

    Directory of Open Access Journals (Sweden)

    N. Partamies

    2006-09-01

    Full Text Available We present ground-based optical, riometer and magnetometer recordings together with Polar UVI and GOES magnetic field observations of a substorm that occurred over Canada on 24 November 1997. This event involved a clear optical onset followed by poleward motion of the aurora as a signature of an expanding auroral bulge. During the expansion phase, there were three distinct types of meso-scale (10–1000 km auroral structures embedded in the bulge: at first a series of equatorward moving auroral arcs, followed by a well-defined spiral pair, and finally north-south directed aurora (a streamer. The spirals occurred several minutes after the onset, and indicate a shear in the field-aligned current. The north-south aligned aurora that formed about 10 min after the onset suggest bursty bulk flow type flows taking place in the central plasma sheet. Polar UVI observations of the polar cap location indicate that the southward drifting arcs were associated with magnetospheric activity within closed field lines, while the auroral streamer was launched by the bulge reaching the polar cap boundary, i.e. the mid-tail reconnection starting on the open field lines. The riometer data imply high energy electron precipitation in the vicinity of the the poleward moving edge of the auroral bulge, starting at the onset and continuing until the formation of the north-south structure. In this paper, we examine this evolving auroral morphology within the context of substorm theories.

  3. The Grand Aurorae Borealis Seen in Colombia in 1859

    CERN Document Server

    Cárdenas, Freddy Moreno; Domínguez, Santiago Vargas

    2015-01-01

    On Thursday, September 1, 1859, the British astronomer Richard Carrington, for the first time ever, observes a spectacular gleam of visible light on the surface of the solar disk, the photosphere. The Carrington Event, as it is nowadays known by scientists, occurred because of the high solar activity that had visible consequences on Earth, in particular reports of outstanding aurorae activity that amazed thousands of people in the western hemisphere during the dawn of September 2. The geomagnetic storm, generated by the solar-terrestrial event, had such a magnitude that the auroral oval expanded towards the equator, allowing low latitudes, like Panama's 9$^\\circ$ N, to catch a sight of the aurorae. An expedition was carried out to review several historical reports and books from the northern cities of Colombia, allowing the identification of a narrative from Monter\\'ia, Colombia (8$^\\circ$ 45' N), that describes phenomena resembling those of an aurorae borealis, such as fire-like lights, blazing and dazzling ...

  4. Ground Observations of Post-Noon Aurora :a Case Study

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The characteristics of the post-noon aurora observed at Antarctic Zhongshan station on June 12, 1999, were discussed and analyzed. In the condition of the magnetic activity is not large(Kp≈l), for post-noon 630. 0 nm emissions, the total fluxes of soft precipitating particles were increasing from 10:50 UT to 13:35 UT and were decreasing from 13 :35 UT to 18 :00 UT in almost monotonous way. Away from noon, the 557. 7 nm emissions increased gradually from 10 :50 UT to 17 :10 UT. The behaviors of the precipitat- ing particles for exciting 630. 0 nm aurora and 557. 7 nm aurora were quite different. The peak intensity of 630. 0 nm and 557. 7 nm emissions appeared at about 13:35 UT and 15:40 UT respectively, the time differ- ence of two peaks is about 2 h. The energy of precipitating electrons remained fairly steady until 15:00 UT when it rose dramatically.

  5. Modeling the breakdown and glow phases during ignition of HID lamps

    Energy Technology Data Exchange (ETDEWEB)

    Liland, K.B.; Peres, I.; Pitchford, L.C.; Boeuf, J.P. [Univ. Paul Sabatier, Toulouse (France)

    1996-12-31

    HID lamps are often ignited by one or more short, high voltage pulses (trigger pulses) superimposed on the low frequency, generator voltage. The authors have developed a self-consistent, fluid model of transient glow discharges to study the breakdown and glow phases in HID lamps from the time of the application of the trigger pulse(s) to the time when there is a fully-developed, quasi-steady state glow discharge. The transition to the thermionic arc is not considered here. Using this model they have investigated the influence of the height, width and number of trigger pulses on the generator voltage required to achieve a steady-state glow discharge. The model used is one-dimensional, and the fundamental variables are the charged particle densities and the potential as functions of distance between the electrodes and time. The minimum voltage needed to initiate a glow discharge, V{sub g}, decreases with increasing current during the trigger pulse and reaches a minimum which is a few volts above the steady-state glow voltage. Results in discharges in argon and argon/mercury mixtures will be presented showing the dependence of V{sub g} on the trigger pulse and on other discharge conditions (gas mixture, external circuit, ...). The calculated, steady-state glow current-voltage characteristic will also be presented.

  6. Mineralization of aqueous pentachlorophenolate by anodic contact glow discharge electrolysis

    Institute of Scientific and Technical Information of China (English)

    Haiming Yang; Meguru Tezuka

    2011-01-01

    Exhaustive mineralization of pentachlorophenolate ion (PCP) in phosphate buffer was carried out using anodic contact glow discharge electrolysis (CGDE), in which plasma was sustained between the electrolyte and anode. During CGDE, PCP degraded smoothly. The amount of total organic carbon decreased significantly, indicating the eventual conversion of the carbon atoms of benzene nucleus to inorganic carbons. Furthermore, chlorine atoms in PCP were liberated as chloride ions. As a primary intermediate product, 2,3,5,6-tetrachloro-1,4-benzoquinone was detected, and oxalate and formate as byproducts were also found. It was revealed that disappearance of PCP obeyed first-order kinetics. The reaction rate was generally unaffected by both O2 and inert gases in the cell, although it decreased by raising initial pH of solution. In addition, a plausible reaction pathway involving hydroxyl radical was proposed.

  7. Flush-mounted probe diagnostics for argon glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Liang, E-mail: xld02345@mail.ustc.edu.cn; Cao, Jinxiang; Liu, Yu; Wang, Jian; Du, Yinchang; Zheng, Zhe; Zhang, Xiao; Wang, Pi [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Jin; Li, Xiao; Qin, Yongqiang; Zhao, Liang [Science and Technology on Space Physics Laboratory, Beijing 100076 (China)

    2014-09-15

    A comparison is made between plasma parameters measured by a flush-mounted probe (FP) and a cylindrical probe (CP) in argon glow discharge plasma. Parameters compared include the space potential, the plasma density, and the effective electron temperature. It is found that the ion density determined by the FP agrees well with the electron density determined by the CP in the quasi-neutral plasma to better than 10%. Moreover, the space potential and effective electron temperature calculated from electron energy distribution function measured by the FP is consistent with that measured by the CP over the operated discharge current and pressure ranges. These results present the FP can be used as a reliable diagnostic tool in the stable laboratory plasma and also be anticipated to be applied in other complicated plasmas, such as tokamaks, the region of boundary-layer, and so on.

  8. Growth of ordered dusty structures in the glow discharge

    CERN Document Server

    Khakhaev, A; Khakhaev, Anatoly; Podriadtchikov, Sergey

    2004-01-01

    In plasma of direct-current glow discharge the dependence of ordered dusty structure volume, shape and density on plasma conditions were investigated. The structure is formed in a field of volume charge. In experimental investigations we used the aluminum oxide macroparticles with diameter up to 60 microns (size distribution function was not determined). Discharge tube was established vertically, has an internal diameter 2.6 cm and space gap between electrodes 45 cm. Particles were injected from the top end of the discharge tube into the plasma of spectral purity neon. Repeatability of randomized experiment results was better than 5% of the measured values. The areas of existence of various dusty ordered structures and their dependence on physical conditions in plasma (discharge current and pressure) were determined. When the interparticle distance in the structure is constant and particle positions have good time stability this structure was defined like "plasma crystal". Otherwise, we observed process of th...

  9. Degradation of linear alkylbenzene sulfonate with contact glow discharge electrolysis

    Science.gov (United States)

    Budikania, Trisutanti; Ibrahim, Febiyanti, Irine Ayu; Utami, Nissa; Saksono, Nelson

    2015-12-01

    Contact Glow Discharge Electrolysis (CGDE) is one of electrolysis plasma technologies. CGDE can produce the hydroxyl radical in a large amount that can be used for wastewater degradation process. This study was conducted to obtain the influence of applied voltage, electrolyte concentration, and anode depth in the LAS degradation using CGDE and review its energy consumption. The greatest LAS degradation is achieved up to 99.14% with low energy consumption of 1149.88 kJ/mmol of the energy consumption that is obtained during 120 minutes by using 600 Volt, 0.02 M of KOH, and 0.5 cm of the anode depth and initial concentration of LAS is 100 ppm.

  10. Glow discharges with electrostatic confinement of fast electrons

    Science.gov (United States)

    Kolobov, V. I.; Metel, A. S.

    2015-06-01

    This review presents a unified treatment of glow discharges with electrostatic confinement of fast electrons. These discharges include hollow cathode discharges, wire and cage discharges, reflect discharges with brush and multirod cathodes, and discharges in crossed electric and magnetic fields. Fast electrons bouncing inside electrostatic traps provide efficient ionization of gas at very low gas pressures. The electrostatic trap effect (ETE) was first observed by Paschen in hollow cathode discharges almost a century ago. The key parameters that define fundamental characteristics of ETE discharges are the ionization length λN, the penetration range, Λ, and the diffusion length λ of the fast electrons, and two universal geometric parameters of the traps: effective width a and length L. Peculiarities of electron kinetics and ion collection mechanism explain experimental observations for different trap geometries. The ETE is observed only at Λ > a, when the penetration range of the γ-electrons emitted by the cathode exceeds the trap width. In the optimal pressure range, when λN > a, and Λ current, Uc tends to its upper limit W/eβγ, where β is the percentage of ions arriving at the cathode and W is the gas ionization cost. In the low-pressure range, Λ > L, Uc rises from hundreds to thousands of volts. The sign of the anode potential fall, Ua, depends on the anode surface Sa and its position. When Sa is large compared to a critical value S*, Ua is negative and small. At Sa value of Ua becomes positive and rises up to 0.5-1 kV with decreasing p ultimately causing discharge extinction. Scaling laws indicate common physics between vacuum discharges and atmospheric pressure micro-discharges. We discuss peculiarities of electron kinetics under different conditions using semi-analytical models. Recent experimental results and applications of glow discharges with electrostatic confinement of fast electrons are described.

  11. Non-conjugate aurora and inter hemispheric currents

    Science.gov (United States)

    Reistad, J. P.; Østgaard, N.; Laundal, K. M.; Oksavik, K.

    2012-04-01

    We look at large scale auroral features using global imagers to obtain simultaneous pictures of both the southern and northern auroral ovals in the ultra violet part of the spectra. During the years 2001 and 2002 the IMAGE satellite was in a favourable position for imaging the aurora borealis (Northern Hemisphere) and the POLAR satellite with its large field-of-view VIS Earth camera had a sporadic coverage of the aurora australis (Southern Hemisphere). In total 19 hours of simultaneous global imaging from different seasons are analysed searching for non-conjugacy in the night side sector. By non-conjugate aurora we mean auroral features appearing in one hemisphere only, or significant differences in intensity between the hemispheres for the same auroral feature. We suggest that our observed large scale asymmetries can be explained in terms of inter hemispheric currents (IHC). Coherent with our earlier findings, we list three possible candidates for producing such inter hemispheric currents based on observations. 1) Hemispherical differences in the solar wind dynamo due to IMF Bx and tilt angle producing different strength of region 1 currents in the conjugate he mispheres, 2) Hemispherical differences in conductivity controlled by the tilt angle only giving rise to IHC on closed field lines, and 3) Field-aligned current components induced by the penetration of the IMF By into the closed magnetosphere. Most of the observed non-conjugate aurora in our dataset can be explained by these candidates only. The IMF By penetration candidate is considered closer. We search for evidence in our data that IMF By 0) can induce an IHC producing stronger aurora on the polar boundary in the Northern (Southern) Hemisphere. Also a second IHC component are predicted from the theory, mapping to the equatorward part of the oval and opposite directed along the magnetic field lines. Using a much larger dataset for one hemisphere only, we show whether these predicted currents can be

  12. AURORA on MEGSAT 1 a photon counting observatory for the Earth UV night-sky background and Aurora emission

    CERN Document Server

    Monfardini, A; Stalio, R; Mahne, N; Battiston, R; Menichelli, M; Mazzinghi, P

    2001-01-01

    A low-mass, low-cost photon-counting scientific payload has been developed and launched on a commercial microsatellite in order to study the near-UV night-sky background emission with a telescope nicknamed 'Notte' and the Aurora emission with 'Alba'. AURORA, this is the name of the experiment, will determine, with the 'Notte' channel, the overall night-side photon background in the 300-400 nm spectral range, together with a particular 2 sup + N sub 2 line (lambda sub c =337 nm). The 'Alba' channel, on the other hand, will study the Aurora emissions in four different spectral bands (FWHM=8.4-9.6 nm) centered on: 367 nm (continuum evaluation), 391 nm (1 sup - N sup + sub 2), 535 nm (continuum evaluation), 560 nm (OI). The instrument has been launched on the 26 September, 2000 from the Baikonur cosmodrome on a modified SS18 Dnepr-1 'Satan' rocket. The satellite orbit is nearly circular (h sub a sub p sub o sub g sub e sub e =648 km, e=0.0022), and the inclination of the orbital plane is 64.56 deg. An overview of...

  13. Aspects of Metal Surface Glowing Mechanisms with Intensive Electron Beam Bombardment

    Directory of Open Access Journals (Sweden)

    I.V. Barsuk

    2012-06-01

    Full Text Available The paper gives a brief description and analysis of the main physical processes which can have an effect on the glowing nature of metal element surfaces in different electric vacuum devices when they are bombarded by electron beams. It has been found that the electron glowing effects on metal surfaces according to the electron energy can be explained with the help of the transition scattering on plasma waves or just with the classical transition radiation effect. This fact is rather important in terms of classical physics interpretation of the observed glowing effects on metal surface elements and techniques optimization of metal and electron beams diagnostics as well.

  14. Note: Rapid reduction of graphene oxide paper by glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bo, Zheng; Qian, Jiajing; Duan, Liangping; Qiu, Kunzan, E-mail: qiukz@zju.edu.cn; Yan, Jianhua; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Han, Zhao Jun [CSIRO Manufacturing Flagship, P.O. Box 218, Bradfield Road, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [CSIRO Manufacturing Flagship, P.O. Box 218, Bradfield Road, Lindfield, New South Wales 2070 (Australia); Institute for Future Environments and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland 4000 (Australia)

    2015-05-15

    This note reports on a novel method for the rapid reduction of graphene oxide (GO) paper using a glow discharge plasma reactor. Glow discharge is produced and sustained between two parallel-plate graphite electrodes at a pressure of 240 mTorr. By exposing GO paper at the junction of negative-glow and Faraday-dark area for 4 min, the oxygen-containing groups can be effectively removed (C/O ratio increases from 2.6 to 7.9), while the material integrality and flexibility are kept well. Electrochemical measurements demonstrate that the as-obtained reduced GO paper can be potentially used for supercapacitor application.

  15. Surface modification of polyester film by glow discharge tunnel at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    XU Xiang-yu; WANG Shou-guo; YE Tian-chun; JING Guang-yin; YU Da-peng

    2004-01-01

    A large-area improved dielectric barrier glow discharge tunnel has been developed for modifying the surface of polyester film at atmospheric pressure with argon and oxygen gas mixtures. The electrical properties of the glow discharge tunnel were studied by simultaneous measurement of the voltage and current. In addition, the effect of the glow discharge tunnel treatment on the surface of polyester film were studied. The resultant modifications of the surface properties of the treated samples were investigated through scanning probe microscopy and contact angle measurement.

  16. 78 FR 52758 - Foreign-Trade Zone 123-Denver, Colorado; Application for Subzone, Pillow Kingdom, Inc., Aurora...

    Science.gov (United States)

    2013-08-26

    ... Kingdom, Inc., Aurora, Colorado An application has been submitted to the Foreign-Trade Zones (FTZ) Board... Pillow Kingdom, Inc. (Pillow Kingdom), located in Aurora, Colorado. The application was...

  17. Depletion of Aurora-A in zebrafish causes growth retardation due to mitotic delay and p53-dependent cell death.

    Science.gov (United States)

    Jeon, Hee-Yeon; Lee, Hyunsook

    2013-03-01

    Aurora-A is a serine/threonine mitotic kinase that is required for centrosome maturation. Many cancer cells over-express Aurora-A, and several reports have suggested that Aurora-A has prognostic value in the clinical treatment of cancer. Therefore, inhibitors for Aurora-A kinase have been developed. However, studies on Aurora-A are largely performed in cancer cell lines and are sometimes controversial. For effective evaluation of Aurora-A inhibitors in cancer treatment, it is essential to understand its function at the organism level. Here, we report the crucial functions of Aurora-A in homeostasis of spindle organization in mitosis using zebrafish embryogenesis as a model system. Using morpholino technology, we show that depletion of Aurora-A in zebrafish embryogenesis results in short bent trunks, accompanied by growth retardation and eventual cell death. Live-imaging and immunofluorescence analyses of the embryos revealed that the developmental defects are due to problems in mitosis, manifested through monopolar and disorganized spindle formation. Aurora-A-depleted cells exhibited mitotic arrest with congression failure, leading to activation of the spindle assembly checkpoint. Cell death in the absence of Aurora-A was partially rescued by co-injection of the p53 morpholino, suggesting that apoptosis after Aurora-A depletion is p53-dependent. The clinical implications of these results relate to the indication that Aurora-A inhibitors may be effective towards cancers with intact p53.

  18. Proteomic analysis of human metaphase chromosomes reveals Topoisomerase II alpha as an Aurora B substrate

    DEFF Research Database (Denmark)

    Morrison, Ciaran; Henzing, Alexander J; Jensen, Ole Nørregaard;

    2002-01-01

    The essential Aurora B kinase is a chromosomal passenger protein that is required for mitotic chromosome alignment and segregation. Aurora B function is dependent on the chromosome passenger, INCENP. INCENP, in turn, requires sister chromatid cohesion for its appropriate behaviour. Relatively few...

  19. 78 FR 64196 - Approval of Subzone Status: Pillow Kingdom, Inc., Aurora, Colorado

    Science.gov (United States)

    2013-10-28

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Approval of Subzone Status: Pillow Kingdom, Inc., Aurora, Colorado On August 21... existing activation limit of FTZ 123, on behalf of Pillow Kingdom, Inc., in Aurora, Colorado....

  20. Polo-Like Kinase-1 Controls Aurora A Destruction by Activating APC/C-Cdh1

    NARCIS (Netherlands)

    van Leuken, Renske; Clijsters, Linda; van Zon, Wouter; Lim, Dan; Yao, XueBiao; Wolthuis, Rob M. F.; Yaffe, Michael B.; Medema, Rene H.; van Vugt, Marcel A. T. M.

    2009-01-01

    Polo-like kinase-1 (Plk1) is activated before mitosis by Aurora A and its cofactor Bora. In mitosis, Bora is degraded in a manner dependent on Plk1 kinase activity and the E3 ubiquitin ligase SCF-beta TrCP. Here, we show that Plk1 is also required for the timely destruction of its activator Aurora A

  1. Bora and Aurora-A continue to activate Plk1 in mitosis.

    Science.gov (United States)

    Bruinsma, Wytse; Macurek, Libor; Freire, Raimundo; Lindqvist, Arne; Medema, René H

    2014-02-15

    Polo-like kinase-1 (Plk1) is required for proper cell division. Activation of Plk1 requires phosphorylation on a conserved threonine in the T-loop of the kinase domain (T210). Plk1 is first phosphorylated on T210 in G2 phase by the kinase Aurora-A, in concert with its cofactor Bora. However, Bora was shown to be degraded prior to entry into mitosis, and it is currently unclear how Plk1 activity is sustained in mitosis. Here we show that the Bora-Aurora-A complex remains the major activator of Plk1 in mitosis. We show that a small amount of Aurora-A activity is sufficient to phosphorylate and activate Plk1 in mitosis. In addition, a fraction of Bora is retained in mitosis, which is essential for continued Aurora-A-dependent T210 phosphorylation of Plk1. We find that once Plk1 is activated, minimal amounts of the Bora-Aurora-A complex are sufficient to sustain Plk1 activity. Thus, the activation of Plk1 by Aurora-A may function as a bistable switch; highly sensitive to inhibition of Aurora-A in its initial activation, but refractory to fluctuations in Aurora-A activity once Plk1 is fully activated. This provides a cell with robust Plk1 activity once it has committed to mitosis.

  2. A single TiO2-coated side-glowing optical fiber for photocatalytic wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    HU Yan; XU Jingjing; YUAN Chunwei; LIN Jian; YIN Zhidong

    2005-01-01

    By means of TiO2-layer-on-SiO2-layer, anatase TiO2 was deposited on novel side- glowing optical fibers, which can provide side UV radiation along the whole fiber length. FE-SEM images show that the double layers adhered well to the side-glowing optical fiber, and the TiO2 coating was homogeneous and smooth. The decomposition reaction of reactive brilliant red dye X-3B on a single TiO2-coated side-glowing optical fiber indicated that the side-scattering UV light intensity was strong enough for photocatalytic oxidation reaction. Therefore, TiO2-coated side-glowing optical fibers open up a new way to use the optical fiber reactor in photocatalytic wastewater treatment.

  3. Effect of Ne Glow Discharge on Ion Density Control in LHD

    Institute of Scientific and Technical Information of China (English)

    S.Morita; M. Goto; S. Masuzaki; H. Suzuki; K. Tanaka; H. Nozato; Y. Takeiri; J. Miyazawa; LHD esperimental group

    2004-01-01

    Neon glow discharge cleaning was firstly attempted in Large Helical Device (LHD) instead of He glow discharge to remove hydrogen neutrals and to control the ion density, ni. The Ne glow discharge continued for 8 hours overnight after a three-day experiment. At the second night Halpha emission became weaker than the emission usually observed in the He glow discharge. A clear reduction of the hydrogen influx was also observed in neutral beam injection (NBI) discharges with Ne puff, whereas the neon recycling was strongly enhanced with appearance of a flat density profile. As a result, the lowest density limit was further reduced down to 0.2 times10 13 ,cm-3. The use of Ar puff formed a peaked density profile with a high Ti of 7 keV.

  4. Microhollow Glow Discharge Instrument for In Situ Lunar Surface Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) and Penn State University (PSU) propose to develop a highly sensitive spectrometer based on glow discharge plasma emission for the...

  5. Model of the Crustal Magnetic Field in the Martian Aurora Zone

    Institute of Scientific and Technical Information of China (English)

    TONG Dong-Sheng; CHEN Chu-Xin

    2011-01-01

    It is well known that aurorae are prominent on planets with a global magnetic field and occur where open magnetic Geld lines converge. The UV spectrometer used for investigating the characteristics of the atmosphere of Mars (SPICAM) on board the Mars Express made the first observation of auroral-type emission in the cusp region of the strong crustal magnetic field on Mars and found that the arc of the Martian aurora zone is very narrow in width, which obviously differs from that of other planets. Based on the observation, we put forward a model of a crustal magnetic field on the Martian aurora zone through the morphology of Martian aurorae. In the model, equivalent currents are proposed; the topology and magnitude of the magnetic field generated by these equivalent currents are consistent with that of the crustal magnetic field in the Martian aurora zone. The morphology of the Martian aurora zone generated through the model matches well with the observations made by the Mars Express orbiter.%It is well known that aurorae are prominent on planets with a global magnetic field and occur where open magnetic field lines converge.The UV spectrometer used for investigating the characteristics of the atmosphere of Mars (SPICAM) on board the Mars Express made the first observation of auroral-type emission in the cusp region of the strong crustal magnetic field on Mars and found that the arc of the Martian aurora zone is very narrow in width,which obviously differs from that of other planets.Based on the observation,we put forward a model of a crustal magnetic field on the Martian aurora zone through the morphology of Martian aurorae.In the model,equivalent currents are proposed;the topology and magnitude of the magnetic field generated by these equivalent currents are consistent with that of the crustal magnetic field in the Martian aurora zone.The morphology of the Martian aurora zone generated through the model matches well with the observations made by the Mars Express

  6. The Effects of Lamp Spectral Distribution on Sky Glow over Observatories

    Science.gov (United States)

    2015-01-01

    MAR 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE The Effects of Lamp Spectral Distribution on Sky Glow...overhead sky glow as a function of distance up to 300 km, from a variety of lamp types, including common gas discharge lamps and several types of LED... lamps . We conclude for both professional, and especially cultural (visual), astronomy, that low-pressure sodium and narrowspectrum amber LED lamps

  7. Modeling of asymmetric pulsed phenomena in dielectric-barrier atmospheric-pressure glow discharges

    Energy Technology Data Exchange (ETDEWEB)

    Ha Yan [College of Mathematics and Computer Science, Hebei University, Baoding 071002 (China); Wang Huijuan [School of Mathematics and Physics, North China Electric Power University, Baoding 071003 (China); Wang Xiaofei [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

    2012-01-15

    Asymmetric current pulses in dielectric-barrier atmospheric-pressure glow discharges are investigated by a self-consistent, one-dimensional fluid model. It is found that the glow mode and Townsend mode can coexist in the asymmetric discharge even though the gas gap is rather large. The reason for this phenomenon is that the residual space charge plays the role of anode and reduces the gap width, resulting in the formation of a Townsend discharge.

  8. The Effects of Lamp Spectral Distribution on Sky Glow over Observatories

    Science.gov (United States)

    Luginbuhl, C. B.; Boley, P. A.; Davis, D. R.; Duriscoe, D. M.

    2015-03-01

    Using a wavelength-generalized version of the Garstang (1991) model, we evaluate overhead sky glow as a function of distance up to 300 km, from a variety of lamp types, including common gas discharge lamps and several types of LED lamps. We conclude for both professional, and especially cultural (visual), astronomy, that low-pressure sodium and narrow-spectrum amber LED lamps cause much less sky glow than all broad-spectrum sources.

  9. Effects of norms, warm-glow and time use on household recycling

    OpenAIRE

    Halvorsen, Bente

    2004-01-01

    Abstract: The aim of this paper is to quantify the relative importance of motivations based on warm-glow, social and moral norms and cost of time used recycling on household recycling efforts. We also test for crowding-out of intrinsic motivations when recycling is perceived as mandatory. We find that the most important variable increasing household recycling efforts is agreeing that recycling is a pleasant activity in itself, which may be interpreted as a warm-glow effect. The...

  10. Evolution of the Global Aurora During Positive IMP Bz and Varying IMP By Conditions

    Science.gov (United States)

    Cumnock, J. A.; Sharber, J. R.; Heelis. R. A.; Hairston, M. R.; Carven, J. D.

    1997-01-01

    The DE 1 imaging instrumentation provides a full view of the entire auroral oval every 12 min for several hours during each orbit. We examined five examples of global evolution of the aurora that occurred during the northern hemisphere winter of 1981-1982 when the z component of the interplanetary magnetic field was positive and the y component was changing sign. Evolution of an expanded auroral emission region into a theta aurora appears to require a change in the sign of By during northward interplanetary magnetic field (IMF). Theta aurora are formed both from expanded duskside emission regions (By changes from positive to negative) and dawnside emission regions (By changes from negative to positive), however the dawnside-originating and duskside-originating evolutions are not mirror images. The persistence of a theta aurora after its formation suggests that there may be no clear relationship between the theta aurora pattern and the instantaneous configuration of the IMF.

  11. Expression of Aurora-B and FOXM1 predict poor survival in patients with nasopharyngeal carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Pei-Yu; Luo, Dong-Hua; Mai, Hai-Qiang [State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou (China); Sun Yat-sen University Cancer Center, Department of Nasopharyngeal Carcinoma, Guangzhou (China); Li, Yan; Zeng, Ting-Ting; Li, Meng-Qing [State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou (China); Hou, Xue; Zhang, Li [State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou (China); Sun Yat-sen University Cancer Center, Department of Medical Oncology, Guangzhou (China)

    2015-08-15

    The purpose of this work was to investigate the relationship between Aurora-B, FOXM1, and clinical outcomes in patients with nasopharyngeal carcinoma (NPC) who were treated with a combination of induction chemotherapy and radiotherapy. The expression of Aurora-B and FOXM1 were investigated by immunohistochemistry using a tissue microarray (TMA) containing samples from 166 NPC patients who were treated with cisplatin (DDP) + fluorouracil (5-FU) induction chemotherapy and radiotherapy between 1999 and 2005. The relationship of Aurora-B, FOXM1, and survival of these NPC patients was analyzed. Informative TMA results were obtained in 91 tumor cases for Aurora-B and 93 tumor cases for FOXM1. The 8-year failure-free survival rate (FFS) for the Aurora-B-negative and Aurora-B-positive group was 65.6 and 37.3 %, respectively (p = 0.024), and the 8-year distant FFS (D-FFS) rate was 65.6 and 41.5 %, respectively (p = 0.047). The 8-year overall survival (OS) in the FOXM1-negative group was moderately higher than in the FOXM1-positive group (58.4 vs 39.1 %, p = 0.081). Cox regression analysis revealed that for FFS, Aurora-B expression was a significant prognostic factor (p = 0.025), while for D-FFS, Aurora-B expression was a marginally significant prognostic factor (p = 0.056). When FOXM1 expression was analyzed, the Cox regression analyses showed that FOXM1 expression was a marginally significant prognostic factor (p = 0.056) for OS. Correlation analysis showed that Aurora-B and FOXM1 expression had no significant correlation. Aurora-B and FOXM1 were both adverse prognostic markers for NPC patients treated with chemoradiotherapy. However, the two markers had no significant correlation. (orig.) [German] Ziel war die Untersuchung der Beziehung zwischen Aurora-B, FOXM1 und den klinischen Ergebnissen bei Patienten mit nasopharyngealem Karzinom (NPC), die mit einer Kombinationstherapie aus Induktionschemotherapie und Radiotherapie behandelt wurden. Die Expression von Aurora-B und

  12. Second Order Fluid Glow Discharge Model Sustained by Different Source Terms%Second Order Fluid Glow Discharge Model Sustained by Different Source Terms

    Institute of Scientific and Technical Information of China (English)

    D. GUENDOUZ; A. HAMID; A. HENNAD

    2011-01-01

    Behavior of charged particles in a DC low pressure glow discharge is studied. The electric properties of the glow discharge in argon, maintained by a constant source term with uni- form electron and ion generation, between two plane electrodes or by secondary electron emission at the cathode, are determined. A fluid model is used to solve self-consistently the first three moments of the Boltzmann equation coupled with the Poisson equation. The stationary spatial distribution of the electron and ion densities, the electric potential, the electric field, and the electron energy, in a two-dimensional (2D) configuration, are presented.

  13. Study of the glow curve structure of the minerals separated from black pepper (Piper nigrum L.)

    Science.gov (United States)

    Guzmán, S.; Ruiz Gurrola, B.; Cruz-Zaragoza, E.; Tufiño, A.; Furetta, C.; Favalli, A.; Brown, F.

    2011-04-01

    The inorganic mineral fraction extracted from black pepper (Piper nigrum L.) has been analysed using a thermoluminescence (TL) method, investigating the glow curve structure, including an evaluation of the kinetic parameters. Different grain sizes, i.e. 10, 74, and 149 μm, were selected from commercial black pepper. The X-ray diffraction of the inorganic fraction shows that quartz is the main mineral present in it. The samples were exposed to 1-25 kGy doses by gamma rays of 60Co in order to analyse the thermally stimulated luminescence response as a function of the delivered dose. The glow curves show a complex structure for different grain sizes of the pepper mineral samples. The fading of the TL signal at room temperature was obtained after irradiation, and it was observed that the maximum peaks of the glow curves shift towards higher values of the temperature when the elapsed time from irradiation increases. It seems that the fading characteristic may be related to a continuous trap distribution responsible for the complex structure of the glow curve. Similar glow curves structure behaviour was found under ultraviolet irradiation of the samples. The activation energy and the frequency factor were determined from the glow curves of different grain sizes using a deconvolution programme because of the evident complexity of the structure.

  14. Modeling plasma glow discharges in Air near a Mach 3 bow shock with KRONOS

    Science.gov (United States)

    Rassou, Sebastien; Labaune, Julien; Packan, Denis; Elias, Paul-Quentin

    2016-09-01

    In this work, plasma glow discharge in Air is modeled near a Mach 3 bow shock. Numerical simulations are performed using the coupling KRONOS which have been developed at ONERA. The flow field is modeled using the code CFD: CEDRE from ONERA and the electrical and plasma part by the EDF open-source code CODE_SATURNE. The plasma kinetic modeling consists on a two-term Boltzmann equation solver and a chemical reaction solver depending of the electric field. The coupling KRONOS is fully parallelized and run on ONERA supercomputers. The shock wave is formed by the propagation of a supersonic flow (M = 3) through a truncated conical model mounted with a central spike. Depending on the spike's voltage value, corona, glow or arc regime could be obtained in a steady flow. The parameters for the supersonic flow and the spike configurations are chosen to be in glow discharge regime and to reproduce the experimental setup. In our simulations, 12 species and 80 reactions (ionization, electronic or vibrational excitation, attachment etc ...) are considered to properly model the glow discharge and the afterglow. In a stationary flow, glow discharge is observed only at the upstream of the shock wave near the high voltage spike. Behind the bow shock, in the afterglow, negative ions are provided by electrons attachment with O2. The negative ions flow convection ensures the electrical conduction and the establishment of the glow discharge.

  15. [Spatial distribution of electrons with high energy in atmospheric pressure glow discharge excited by DC voltage].

    Science.gov (United States)

    Liu, Zhi-qiang; Jia, Peng-ying; Liu, Tie

    2013-09-01

    Atmospheric pressure glow discharge excited by a DC voltage was realized in a 6 mm air gap by using a needle-water electrode discharge device. The atompheric pressure glow discharge has characteristic regions such as a cathode fall, a negative glow, a Faraday dark space, a positive column and an anode glow. The discharge is a normal glow through analyzing its voltage-current curve. The emission intensity of 337.1 nm spectral line from the second positive system of N2 was investigated because it can indicate the electron density with high energy. Results show that the maxima of high energy electrons appears in the vicinity of the needle tip, and it almost remains constant at other locations. The density of high energy electrons decreases with increasing the voltage. Similarly, it decreases with increasing the value of the ballast resistor. Oxygen atom is important for the sterilization and disinfection. The distribution of oxygen atom was also investigated by optical emission spectroscopy. It was found that the oxygen distribution is similar with the distribution of high energy electrons. These results are important for the application of atmospheric pressure glow discharge in environmental protection and biological treatment.

  16. TL glow curve analysis of UV, beta and gamma induced limestone collected from Amarnath holy cave

    Directory of Open Access Journals (Sweden)

    Vikas Dubey

    2015-01-01

    Full Text Available The paper reports themoluminescence glow curve analysis of UV (ultraviolet, β (beta and γ (gamma induced limestone collected from Amarnath holy cave. The collected natural sample was characterized by X-ray diffraction (XRD technique and crystallite size calculated by Scherer's formula. Surface morphology and particle size was calculated by transmission electron microscopy (TEM study. Effect of annealing temperature on collected lime stone examined by TL glow curve study. The limestone was irradiated by UV radiation (254 nm source and the TL glow curve recorded for different UV exposure time. For beta irradiation Sr90 source was used and is shows intense peak at 256 °C with a shoulder peak at higher temperature range. For gamma radiation Co60 source and TL glow curve recorded for different doses of gamma. The kinetic parameters calculation was performed for different glow curve by computerized glow curve deconvolution (CGCD technique. The chemical composition of natural limestone was analyzed by energy dispersive X-ray spectroscopy (EDXS.

  17. Jupiter's Mid-Infrared Aurora: Solar Connection and Minor Constituents

    Science.gov (United States)

    Kostiuk, Theodore; Livengood, T.A.; Fast, K.E.; Hewagama, T.; Schmilling, F.; Sonnabend, G.; Delgado, J.

    2009-01-01

    High spectral resolution in the 12 pin region of the polar regions of Jupiter reveal unique information on auroral phenomena and upper stratospheric composition. Polar aurorae in Jupiter's atmosphere radiate; throughout the electromagnetic spectrum from X-ray through mid-infrared (mid-IR, 5 - 20 micron wavelength). Voyager IRIS data and ground-based. spectroscopic measurements of Jupiter's northern mid-IR aurora acquired since 1982, reveal a correlation between auroral brightness and solar activity that has not been observed in Jovian aurora at other wavelengths. Over nearly three solar cycles, Jupiter auroral ethane, emission brightness and solar 10.7-cm radar flux and sunspot number are positively correlated with high confidence. Ethane line emission intensity varies over tenfold between low and high scalar activity periods. Detailed measurements have been made using the GSFC HIPWAC spectrometer at the NASA IRTF since the last solar maximum, following the mid-IR emission through the declining phase toward solar minimum. An even more convincing correlation with solar activity is evident in these data. The spectra measured contain features that cannot be attributed to ethane and are most likely spectra of minor constituents whose molecular bands overlap the v9 band of ethane. Possible candidates are allene, propane, and other higher order hydrocarbons. These features appear to be enhanced in the active polar regions. Laboratory measurements at comparable spectral resolution of spectra of candidate molecules will be used to identify the constituents. Current analyses of these results will be described, including planned measurements on polar ethane line emission scheduled through the rise of the next solar maximum beginning in 2009, with a steep gradient to a maximum in 2012. This work is relevant to the Juno mission and to the development of the NASA/ESA Europa Jupiter System Mission.

  18. AURORA BOREALIS - European Research Icebreaker With Drilling Capability

    Science.gov (United States)

    Biebow, N.; Lembke-Jene, L.; Kunz-Pirrung, M.; Thiede, J.

    2008-12-01

    The polar oceans are the least known areas of the globe, in although they hold the key to many of our climate´s secrets. How does the sea ice coverage and the sea water properties change? How do plants and animals survive under the most extreme conditions of the earth? Which information of past climate change can be read from the sediments at the sea-floor and how can the future changing climate be predicted? In order to answer such and further questions, for the moment a hypermodern research vessel, the AURORA BOREALIS, is planned, which can handle the cool summers and freezing winters of the polar oceans and which can drill deep into the sea floor. AURORA BOREALIS will be the most advanced Research Icebreaker in the world with a multi-functional role of drilling in deep ocean basins and supporting climate/environmental research and decision support for stakeholder governments for the next 35-40 years. It will have a high icebreaking capacity to penetrate autonomously (single ship operation) into the central Arctic Ocean with more than 2.5 meters of ice cover, during all seasons of the year. The new technological features will include dynamic positioning in closed sea- ice cover, satellite navigation and ice-management support and the deployment and operation of Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUVs) from the twin moon-pools. A unique feature of the vessel is the deep-sea drilling rig, which will enable sampling of the ocean floor and sub-sea up to 5000 m water and 1000 m penetration at the most inhospitable places on earth. The drilling capability will be deployed in both Polar Regions on the long run and AURORA BOREALIS will be the only vessel worldwide that could undertake this type of scientific investigation.

  19. Basal aurora kinase B activity is sufficient for histone H3 phosphorylation in prophase

    Directory of Open Access Journals (Sweden)

    Ly-Thuy-Tram Le

    2013-02-01

    Histone H3 phosphorylation is the hallmark of mitosis deposited by aurora kinase B. Benzo[e]pyridoindoles are a family of potent, broad, ATP-competitive aurora kinase inhibitors. However, benzo[e]pyridoindole C4 only inhibits histone H3 phosphorylation in prophase but not in metaphase. Under the C4 treatment, the cells enter into mitosis with dephosphorylated histone H3, assemble chromosomes normally and progress to metaphase, and then to anaphase. C4 also induces lagging chromosome in anaphase but we demonstrated that these chromosome compaction defects are not related to the absence of H3 phosphorylation in prophase. As a result of C4 action, mitosis lasts longer and the cell cycle is slowed down. We reproduced the mitotic defects with reduced concentrations of potent pan aurora kinase as well as with a specific aurora B ATP-competitive inhibitor; we therefore propose that histone H3 phosphorylation and anaphase chromosome compaction involve the basal activity of aurora kinase B. Our data suggest that aurora kinase B is progressively activated at mitosis entry and at anaphase onset. The full activation of aurora kinase B by its partners, in prometaphase, induces a shift in the catalytic domain of aurora B that modifies its affinity for ATP. These waves of activation/deactivation of aurora B correspond to different conformations of the chromosomal complex revealed by FRAP. The presence of lagging chromosomes may have deleterious consequences on the daughter cells and, unfortunately, the situation may be encountered in patients receiving treatment with aurora kinase inhibitors.

  20. Portable parallel portfolio optimization in the Aurora Financial Management System

    Science.gov (United States)

    Laure, Erwin; Moritsch, Hans

    2001-07-01

    Financial planning problems are formulated as large scale, stochastic, multiperiod, tree structured optimization problems. An efficient technique for solving this kind of problems is the nested Benders decomposition method. In this paper we present a parallel, portable, asynchronous implementation of this technique. To achieve our portability goals we elected the programming language Java for our implementation and used a high level Java based framework, called OpusJava, for expressing the parallelism potential as well as synchronization constraints. Our implementation is embedded within a modular decision support tool for portfolio and asset liability management, the Aurora Financial Management System.

  1. Degradation of Anionic Dye Eosin by Glow Discharge Electrolysis Plasma

    Institute of Scientific and Technical Information of China (English)

    GAO Jinzhang; MA Dongping; GUO Xiao; WANG Aixiang; FU Yan; WU Jianlin; YANG Wu

    2008-01-01

    This paper describes a novel method for the degradation of eosin by using glow discharge electrolysis (GDE). The effects of various parameters on the removal efficiency were studied. It was found that the eosin degradation could be raised considerably by increasing the applied voltage and the initial concentration, or by decreasing pH of the aqueous solution. Fe2+ ion had an evident accelerating effect on the eosin degradation. The degradation process of eosin obeyed a pseudo-first-order reaction. The relationship between the degradation rate constant κ and the reaction temperature T could be expressed by Arrhenius equation with which the apparent activation energy Ea of 14.110 kJ. Mol-1 and the pre-exponential factor k0 of 2.065×10-1 min-1 were obtained, too. The determination of hydroxyl radical was carried out by using N, N-dimethyl -p-nitrosoaniline (RNO) as a scavenger. The results showed that the hydroxyl radical plays an important role in the degradation process.

  2. Aqueous organic dye discoloration induced by contact glow discharge electrolysis.

    Science.gov (United States)

    Wang, Lei

    2009-11-15

    In this study, effects of applied voltage, types of electrolytes, initial substrate concentration, radical scavengers and iron salts on the aqueous polar brilliant B (PBB) discoloration induced by contact glow discharge electrolysis (CGDE) were examined. Experimental results showed that the PBB discoloration proceeded faster in chloride solution than in phosphate or sulfate solutions. Increasing the applied voltage from 450V to 550V did not enhance the discoloration when the applied current was kept constant. Addition of a small amount of hydroxyl scavengers (methanol) to the solution decreased the discoloration, whereas addition of a large amount of methanol increased the discoloration. During the treatment, TOC of the solution smoothly decreased whereas COD of the solution gradually increased due to the production of H(2)O(2) in the liquid phase. Iron salts enhanced the discoloration significantly due to the additional Fenton reaction. Higher initial PBB concentration resulted in lower color removal efficiency, indicating that the PBB discoloration by CGDE did not observe the first-order reaction kinetics in inert electrolytic solutions.

  3. Platinum and Iridium Coatings Obtained by Double Glow Plasma Technology

    Institute of Scientific and Technical Information of China (English)

    WU Wangping; CHEN Zhaofeng; CHEN Zhou; CONG Xiangna; QIU Jinlian

    2012-01-01

    Pt and Ir coatings were produced by double glow plasma technology on the surface of Ti alloy substrates.The chemical compositions of the coatings were determined by X-ray diffraction and X-ray photoelectron spectroscopy.The microstructure and morphology of the coatings were observed by scanning electron microscopy.The hardness and elastic modulus of the coatings were estimated by nanoindentation.The measurements of adhesive forces of the coatings were performed with scratch tester.The results indicated that the Pt and Ir coatings displayed the preferred (220) orientation due to the initial nuclei with preferred growth on the surface of the substrates.The interface between the Pt coating and substrate exhibited no evidence of delamination.The Ir coating was composed of irregular columnar grains with many nanovoids at the interface between the coating and substrate.The mean values of hardness for Pt and Ir coatings were 0.9 GPa and 9 GPa,respectively.The elastic modulus of Pt and Ir coatings were 178 GPa and 339 GPa,respectively.The adhesive forces of the Pt and Ir coatings were about 66.4 N and 55 N,respectively.The Pt and Ir coatings adhered well to the Ti alloy substrates.

  4. Dayside aurora and the role of IMF ∣By∣/∣Bz∣: detailed morphology and response to magnetopause reconnection

    Directory of Open Access Journals (Sweden)

    W. F. Denig

    2004-01-01

    (convection current, more intense FAC sheets and PMAF activity in the midday sector. The strong IMF regulation of the dayside BPS aurora, consisting of keV electrons, and its location with respect to the green line auroral gap (precipitation void, indicate that it is an important signature of the reconnection process, located on open boundary layer field lines. The observed longitudinal bifurcation of the auroral brightenings (EBIs preceding PMAFs is consistent with antiparallel magnetopause reconnection. Key words. Magnetospheric physics (auroral phenomena magnetopause, cusp, and boundary layers: solar windmagnetosphere interactions – Ionosphere (particle precipitation

  5. Dynamic rayed aurora and enhanced ion-acoustic radar echoes

    Directory of Open Access Journals (Sweden)

    E. M. Blixt

    2005-01-01

    Full Text Available The generation mechanism for naturally enhanced ion-acoustic echoes is still debated. One important issue is how these enhancements are related to auroral activity. All events of enhanced ion-acoustic echoes observed simultaneously with the EISCAT Svalbard Radar (ESR and with high-resolution narrow field-of-view auroral imagers have been collected and studied. Characteristic of all the events is the appearance of very dynamic rayed aurora, and some of the intrinsic features of these auroral displays are identified. Several of these identified features are directly related to the presence of low energy (10-100eV precipitating electrons in addition to the higher energy population producing most of the associated light. The low energy contribution is vital for the formation of the enhanced ion-acoustic echoes. We argue that this type of aurora is sufficient for the generation of naturally enhanced ion-acoustic echoes. In one event two imagers were used to observe the auroral rays simultaneously, one from the radar site and one 7km away. The data from these imagers shows that the auroral rays and the strong backscattering filaments (where the enhanced echoes are produced are located on the same field line, which is in contrast to earlier statements in the litterature that they should be separated.

  6. Small-scale characteristics of extremely high latitude aurora

    Directory of Open Access Journals (Sweden)

    J. A. Cumnock

    2009-09-01

    Full Text Available We examine 14 cases of an interesting type of extremely high latitude aurora as identified in the precipitating particles measured by the DMSP F13 satellite. In particular we investigate structures within large-scale arcs for which the particle signatures are made up of a group of multiple distinct thin arcs. These cases are chosen without regard to IMF orientation and are part of a group of 87 events where DMSP F13 SSJ/4 measures emissions which occur near the noon-midnight meridian and are spatially separated from both the dawnside and duskside auroral ovals by wide regions with precipitating particles typical of the polar cap. For 73 of these events the high-latitude aurora consists of a continuous region of precipitating particles. We focus on the remaining 14 of these events where the particle signatures show multiple distinct thin arcs. These events occur during northward or weakly southward IMF conditions and follow a change in IMF By. Correlations are seen between the field-aligned currents and plasma flows associated with the arcs, implying local closure of the FACs. Strong correlations are seen only in the sunlit hemisphere. The convection associated with the multiple thin arcs is localized and has little influence on the large-scale convection. This also implies that the sunward flow along the arcs is unrelated to the overall ionospheric convection.

  7. Preservation of minimally processed 'aurora-1' peaches using additives

    Directory of Open Access Journals (Sweden)

    Ramilo Nogueira Martins

    2011-12-01

    Full Text Available 'Aurora-1' peaches establishes an interesting alternative as a minimally processed product, due to its characteristics like flavor, color, smell, and also because of its handling resistance. However, it has a short shelf life after a fresh-cut due to enzymatic browning and stone cavity collapse. The main purpose of this research was to test the additive with antioxidant effect to prevent browning in minimally processed 'Aurora-1' peaches. The minimal processing consists of washing, sanitizing, peelings and fruit stone extraction. After that, longitudinal cuts were made to obtain eight segments per fruit. The slices were immersed into the following treatment solutions: control (immersion in 2% ascorbic acid; 2% ascorbic acid + 2% calcium chloride; 1% sodium isoascorbate; 1% citric acid; 1% L-cysteine hydrochloride. The products were placed into rigid polystyrene trays branded MEIWA M-54, covered with 14 µm PVC film (OmnifilmTM and kept in cold storage at 3ºC ± 2ºC and 65% RH for twelve days, and evaluated each three days. Appraised variables were appearance, soluble solids, titratable acidity, soluble carbohydrates and reducing sugars, total and soluble pectin, ascorbic acid, and peroxidase and polyphenol oxidase enzyme activity. L-cysteine gave to the minimally processed products a shelf life of twelve days, limmited by off-flavor. The treatment with ascorbic acid was efficient to maintainthe ascorbic acid content, with a shelf-life of nine days, limited by enzymatic browning.

  8. Aurora candidates from the chronicle of Qíng dynasty in several degrees of relevance

    Science.gov (United States)

    Kawamura, Akito D.; Hayakawa, Hisashi; Tamazawa, Harufumi; Miyahara, Hiroko; Isobe, Hiroaki

    2016-10-01

    We present the result of a survey of sunspots and auroras in Qíngshǐgǎo (清史稿), a draft chronicle of Qíng dynasty, for the period of 1559-1912 CE. This is a sequel to a series of works surveying historical sunspot and aurora records, and providing online data to the scientific community regarding the attained results. In total of this Qíngshǐgǎo survey, we found 111 records of night-sky luminous events with such keywords as vapor (氣, qì), cloud (雲, yún), and light (光, guāng), which may indicate auroras as well as some other phenomena. Similarly, a keyword survey for sunspots was conducted, but no sunspot record was found. In comparison with the aurora records in the western world, we found that 14 of the 111 records have a corresponding record of simultaneous observation in the western world, and hence are very likely to be aurora. In order to investigate the likeliness of the remainder of the record being aurora, we calculated the lunar age and the phase of a solar cycle for each record. After these calculations, a notable fraction of these records clustered near the full moon were to be found statistically doubtful in considerations with atmospheric optics; meanwhile, a few records of observations near the new moon could be more likely interpreted as being auroras, including three records during the Maunder minimum.

  9. Excess F-actin mechanically impedes mitosis leading to cytokinesis failure in X-linked neutropenia by exceeding Aurora B kinase error correction capacity.

    Science.gov (United States)

    Moulding, Dale A; Moeendarbary, Emad; Valon, Leo; Record, Julien; Charras, Guillaume T; Thrasher, Adrian J

    2012-11-01

    The constitutively active mutant of the Wiskott-Aldrich Syndrome protein (CA-WASp) is the cause of X-linked neutropenia and is linked with genomic instability and myelodysplasia. CA-WASp generates abnormally high levels of cytoplasmic F-actin through dysregulated activation of the Arp2/3 complex leading to defects in cell division. As WASp has no reported role in cell division, we hypothesized that alteration of cell mechanics because of increased F-actin may indirectly disrupt dynamic events during mitosis. Inhibition of the Arp2/3 complex revealed that excess cytoplasmic F-actin caused increased cellular viscosity, slowed all phases of mitosis, and perturbed mitotic mechanics. Comparison of chromosome velocity to the cytoplasmic viscosity revealed that cells compensated for increased viscosity by up-regulating force applied to chromosomes and increased the density of microtubules at kinetochores. Mitotic abnormalities were because of overload of the aurora signaling pathway as subcritical inhibition of Aurora in CA-WASp cells caused increased cytokinesis failure, while overexpression reduced defects. These findings demonstrate that changes in cell mechanics can cause significant mitotic abnormalities leading to genomic instability, and highlight the importance of mechanical sensors such as Aurora B in maintaining the fidelity of hematopoietic cell division.

  10. Non-Thermal Equilibrium Atmospheric Pressure Glow-Like Discharge Plasma Jet

    Science.gov (United States)

    Chang, Zhengshi; Yao, Congwei; Zhang, Guanjun

    2016-01-01

    Non-thermal equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications, and the uniform APPJ is more favored. Glow discharge is one of the most effective methods to obtain the uniform discharge. Compared with the glow dielectric barrier discharge (DBD) in atmospheric pressure, pure helium APPJ shows partial characteristics of both the glow discharge and the streamer. In this paper, considering the influence of the Penning effect, the electrical and optical properties of He APPJ and Ar/NH3 APPJ were researched. A word “Glow-like APPJ” is used to characterize the uniformity of APPJ, and it was obtained that the basic characteristics of the glow-like APPJ are driven by the kHz AC high voltage. The results can provide a support for generating uniform APPJ, and lay a foundation for its applications. supported by National Natural Science Foundation of China (Nos. 51307133, 51125029, 51221005) and the Fundamental Research Funds for the Central Universities of China (Nos. xjj2012132, xkjc2013004)

  11. The charge spectrum of positive ions in a hydrogen aurora

    Science.gov (United States)

    Lynch, J.; Pulliam, D.; Leach, R.; Scherb, F.

    1976-01-01

    An auroral ion charge spectrometer was flown into a hydrogen aurora on a Javelin sounding rocket launched from Churchill, Manitoba. The instrument contained an electrostatic analyzer which selected particles with incident energy per unit charge up to 20 keV/charge and an 80-kV power supply which accelerated these ions onto an array of solid state detectors. Ions tentatively identified as H(+), He(+2), and O(+) were detected from 225 to 820 km in altitude. The experiment did not discriminate between H(+) and He(+), or between O(+), N(+), and C(+). Upper limits of highly charged heavy ion abundances have been set at 20% of the He(+2) and 0.15% of the H(+). It is concluded that both terrestrial and solar wind sources play significant roles in auroral ion precipitation.

  12. Exploring the Secrets of the Aurora Second Edition

    CERN Document Server

    Akasofu, Syun-Ichi

    2007-01-01

    This new edition of Exploring the Secrets of the Aurora is based on the author's own experiences as a scientist. It describes the history of progress made in auroral science and magnetospheric physics by providing examples of ideas, controversies, struggles, acceptance, and success. Although no general methodologies are mentioned, the hope is that the reader will learn about the history of progress in auroral science and examples of dealing with the many controversies. This book aims to help young scientific researchers learn how to persevere during periods of controversy and struggles for acceptance. In this second edition, by utilizing multiple examples, Akasofu is successful in demonstrating the importance and usefulness of Synthesis. "Probably the book's most valuable contribution to the history of space physics is precisely the narration of the discovery of substorms.---The book has special features.---Akasofu's coverage of the history of pre-space age solar-terrestrial relations is the most comprehensiv...

  13. Design and synthesis of novel benzoxazole analogs as Aurora B kinase inhibitors.

    Science.gov (United States)

    An, Ying; Lee, Eun; Yu, Yeongji; Yun, Jieun; Lee, Myeong Youl; Kang, Jong Soon; Kim, Woo-Young; Jeon, Raok

    2016-07-01

    A novel series of benzoxazole analogs was designed and synthesized, and their inhibitory activities against Aurora kinases were evaluated. Some of the tested compounds exhibited a promising activity with respect to the inhibition of Aurora B kinase. A structure-activity relationship study indicated that linker length, regiochemistry, and halogen substitution play important roles in kinase inhibitory potency. The binding modes between representative compounds and Aurora kinases were interpreted through a molecular docking study to explain the inhibitory activity and selectivity for Aurora A and B kinases. Compounds 13l and 13q also show an antiproliferative effect on the human tumor cell lines in a dose-dependent manner. The most potent 13q demonstrated good efficacy in the prostate cancer PC-3 tumor xenograft model.

  14. Recent advances in the development of Aurora kinases inhibitors in hematological malignancies

    Science.gov (United States)

    Choudary, Iqra; Barr, Paul M.; Friedberg, Jonathan

    2015-01-01

    Over the last two decades, since the discovery of Drosophila mutants in 1995, much effort has been made to understand Aurora kinase biology. Three mammalian subtypes have been identified thus far which include the Aurora A, B and C kinases. These regulatory proteins specifically work at the cytoskeleton and chromosomal structures between the kinetochores and have vital functions in the early phases of the mitotic cell cycle. Today, there are multiple phase I and phase II clinical trials as well as numerous preclinical studies taking place looking at Aurora kinase inhibitors in both hematologic and solid malignancies. This review focuses on the preclinical and clinical development of Aurora kinase inhibitors in hematological malignancy and discusses their therapeutic potential. PMID:26622997

  15. Identification of Ustilago maydis Aurora kinase as a novel antifungal target.

    Science.gov (United States)

    Tückmantel, Sandra; Greul, Jörg N; Janning, Petra; Brockmeyer, Andreas; Grütter, Christian; Simard, Jeffrey R; Gutbrod, Oliver; Beck, Michael E; Tietjen, Klaus; Rauh, Daniel; Schreier, Peter H

    2011-09-16

    Infestation of crops by pathogenic fungi has continued to have a major impact by reducing yield and quality, emphasizing the need to identify new targets and develop new agents to improve methods of crop protection. Here we present Aurora kinase from the phytopathogenic fungus Ustilago maydis as a novel target for N-substituted diaminopyrimidines, a class of small-molecule kinase inhibitors. We show that Aurora kinase is essential in U. maydis and that diaminopyrimidines inhibit its activity in vitro. Furthermore, we observed an overall good correlation between in vitro inhibition of Aurora kinase and growth inhibition of diverse fungi in vivo. In vitro inhibition assays with Ustilago and human Aurora kinases indicate that some compounds of the N-substituted diaminopyrimidine class show specificity for the Ustilago enzyme, thus revealing their potential as selective fungicides.

  16. Auroras Observed in Portugal in Late 18th Century Obtained from Printed and Manuscript Meteorological Observations

    Science.gov (United States)

    Vaquero, José M.; Trigo, Ricardo M.

    2005-09-01

    We present a new catalogue of observations of the aurora borealis at Lisbon, i.e., at low-latitudes, in the late 18th century by Jacob Præ torius and Henrique Schulze, two German artillery officers. Dates of 18 auroras compiled by Præ torius and Schulze are compared with those published in other catalogues for that period. The number of annual auroras observed by the two Germans is then compared with two indices of solar activity showing a very good level of consistency between all time series. Finally, we have assessed the number of auroras observed taking into consideration the phase of the lunar cycle and the geomagnetic latitude of Lisbon.

  17. Realidad, mito y deseo. La mirada grecolatina de Aurora Luque

    Directory of Open Access Journals (Sweden)

    Virtanen, Ricardo

    2011-08-01

    Full Text Available Aurora Luque’s poetry is one of the most representative of contemporary poetry, located within a Greek culturalism, where myth and reality blend into everyday life. Luque’s poetry is characterized by irony, nonchalance, frivolity and dedramatization. The article presents a series of poems where one can find a demystification of the classical element. A poetry stressed by some topoi such as carpe diem or Catullus’ odio et amo, which have been always represented from a light-hearted glance ruled by the spirit of Eros. The article also emphasizes the play on intertextuality –following Catullus– as well as the epicurean inclination/spirit/passion of the autor.

    La poesía de Aurora Luque representa una de las poéticas más representativas de nuestra contemporaneidad, ubicada dentro de un culturalismo grecista, donde mito y realidad se conjugan dentro de la cotidianidad. La poesía de Luque se caracteriza por su ironía, desenfado, frivolidad y desdramatización. El artículo presenta una serie de poemas donde se produce una desmitificación del elemento clásico. Una poesía marcada por algunos topoi como el carpe diem o el odio et amo catuliano, siempre representados desde una mirada desenfada y dominada por el espíritu del Eros. El artículo destaca además el juego de intertextualidad –en seguimiento de Catulo– así como la vocación epicúrea de la autora.

  18. Forecasting auroras from regional and global magnetic field measurements

    Science.gov (United States)

    Kauristie, Kirsti; Myllys, Minna; Partamies, Noora; Viljanen, Ari; Peitso, Pyry; Juusola, Liisa; Ahmadzai, Shabana; Singh, Vikramjit; Keil, Ralf; Martinez, Unai; Luginin, Alexej; Glover, Alexi; Navarro, Vicente; Raita, Tero

    2016-06-01

    We use the connection between auroral sightings and rapid geomagnetic field variations in a concept for a Regional Auroral Forecast (RAF) service. The service is based on statistical relationships between near-real-time alerts issued by the NOAA Space Weather Prediction Center and magnetic time derivative (dB/dt) values measured by five MIRACLE magnetometer stations located in Finland at auroral and sub-auroral latitudes. Our database contains NOAA alerts and dB/dt observations from the years 2002-2012. These data are used to create a set of conditional probabilities, which tell the service user when the probability of seeing auroras exceeds the average conditions in Fennoscandia during the coming 0-12 h. Favourable conditions for auroral displays are associated with ground magnetic field time derivative values (dB/dt) exceeding certain latitude-dependent threshold values. Our statistical analyses reveal that the probabilities of recording dB/dt exceeding the thresholds stay below 50 % after NOAA alerts on X-ray bursts or on energetic particle flux enhancements. Therefore, those alerts are not very useful for auroral forecasts if we want to keep the number of false alarms low. However, NOAA alerts on global geomagnetic storms (characterized with Kp values > 4) enable probability estimates of > 50 % with lead times of 3-12 h. RAF forecasts thus rely heavily on the well-known fact that bright auroras appear during geomagnetic storms. The additional new piece of information which RAF brings to the previous picture is the knowledge on typical storm durations at different latitudes. For example, the service users south of the Arctic Circle will learn that after a NOAA ALTK06 issuance in night, auroral spotting should be done within 12 h after the alert, while at higher latitudes conditions can remain favourable during the next night.

  19. Apocenter glow in eccentric debris disks: implications for Fomalhaut and $\\epsilon$ Eridani

    CERN Document Server

    Pan, Margaret; Kuchner, Marc J

    2016-01-01

    Debris disks often take the form of eccentric rings with azimuthal asymmetries in surface brightness. Such disks are often described as showing "pericenter glow", an enhancement of the disk brightness in regions nearest the central star. At long wavelengths, however, the disk apocenters should appear brighter than their pericenters: in the long wavelength limit, we find the apocenter/pericenter flux ratio scales as 1+e for disk eccentricity e. We produce new models of this "apocenter glow" to explore its causes and wavelength dependence and study its potential as a probe of dust grain properties. Based on our models, we argue that several far-infrared and (sub)millimeter images of the Fomalhaut and epsilon Eridani debris rings obtained with Herschel, JCMT, SHARC II, ALMA, and ACTA should be reinterpreted as suggestions or examples of apocenter glow. This reinterpretation yields new constraints on the disks' dust grain properties and size distributions.

  20. Discharge Characteristics in Atmospheric Pressure Glow Surface Discharge in Helium Gas

    Institute of Scientific and Technical Information of China (English)

    LI Xue-Chen; WANG Long

    2005-01-01

    @@ Atmospheric pressure glow discharge is observed for the first time in a surface discharge generator in flowing helium. Electrical and optical methods are used to measure the characteristics of atmospheric pressure glow discharge for different voltages. The results show that discharge current waveforms are asymmetric for the different polarities of the applied voltage. A continuous discharge profile with a width of several microseconds appears for per half cycle of the applied voltage when the voltage is increased to a certain value. The short-pulsed discharge and the continuous current would result from the Townsend breakdown and glow discharge mechanisms respectively. The properties of surface discharge in stagnant helium are completely different from that in flowing helium.

  1. Heating rate effect on thermoluminescence glow curves of LiF:Mg,Cu,P+PTFE phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Zaragoza, E. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, Mexico D.F. 04510 (Mexico); Gonzalez, P.R., E-mail: pedro.gonzalez@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca S/N, C.P. 52750, Ocoyoacac, Estado de Mexico (Mexico); Azorin, J. [Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, 09340 Mexico D.F. (Mexico); Furetta, C. [Touro University Rome, Division of Touro College New York, Circne Gianicolense 15-17, 00153 Rome (Italy)

    2011-10-15

    The influence of heating rate on the thermoluminescence (TL) property of LiF:Mg,Cu,P+PTFE was analyzed. The activation energy and the frequency factor as a function of the heating rate were determined. The kinetic parameters and their dependence on the heating rate were evaluated using the sequential quadratic programming glow curve deconvolution (SQPGCD). The results showed that as the heating rate increases, the peak intensity at the maximum (I{sub M}) decreases and shifts to higher temperature; similar behavior of the kinetics parameters was observed. - Highlights: >Heating rate influence on the thermoluminescence (TL) property of LiF:Mg,Cu,P was analyzed. > The kinetic parameters, activation energy and frequency factor were evaluated using the sequential quadratic programming glow curve deconvolution. > The peak intensity at the maximum (I{sub M}) of the glow curves decreases. > Shifts to higher temperature were observed as the heating rate increased. > Similar behavior of the kinetics parameters was noticed.

  2. Self-Consistent Model for Pulsed Direct-Current N2 Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    Liu Chengsen; Wang Dezhen

    2005-01-01

    A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column).Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment.

  3. The aurora sign in a patient with type B Niemann-Pick disease

    Energy Technology Data Exchange (ETDEWEB)

    Costa e. Silva, Eduardo J. da [Instituto Materno Infantil Professor Fernando Figueira, Departamento de Radiologia, Recife, Pernambuco (Brazil); IMIP, Departamento de Radiologia-Rua dos Coelhos, Recife, PE (Brazil); Cavalcanti de Albuquerque, Silvio; Queiroz Praxedes, Eduardo L. de; Amaral, Fernando J. do [Instituto Materno Infantil Professor Fernando Figueira, Departamento de Radiologia, Recife, Pernambuco (Brazil)

    2007-01-15

    The aurora sign, a sonographic sign found on the sagittal and transverse view, refers to multiple bands of ring-down artifacts posterior to the right hemidiaphragm. Parenchymal lung disease should be suspected when this is present. We report a case of type B Niemann-Pick disease with pulmonary involvement and the aurora sign on abdominal sonography. High-resolution CT of the chest showed corresponding thickened interlobular septa. (orig.)

  4. Study of the Effect of Decrease in the Conductivity Ahead of a Shock Wave in a Glow-Discharge Plasma

    Science.gov (United States)

    Baryshnikov, A. S.; Basargin, I. V.; Bobashev, S. V.; Monakhov, N. A.; Popov, P. A.; Sakharov, V. A.; Chistyakova, M. V.

    2016-05-01

    The electrical conductivity of a glow-discharge plasma ahead of a shock wave moving perpendicularly to the discharge axis has been investigated using a double electric probe. The obtained results have shown that the interaction of the shock wave with the glow-discharge plasma is accompanied by a change in its conductivity in the entire investigated volume simultaneously.

  5. Computational modeling of glow discharge-induced fluid dynamics

    Science.gov (United States)

    Jayaraman, Balaji

    Glow discharge at atmospheric pressure using a dielectric barrier discharge can induce fluid flow and operate as an actuator for flow control. The largely isothermal surface plasma generation realized above can modify the near-wall flow structure by means of Lorentzian collisions between the ionized fluid and the neutral fluid. Such an actuator has advantages of no moving parts, performance at atmospheric conditions and devising complex control strategies through the applied voltage. However, the mechanism of the momentum coupling between the plasma and the fluid flow is not yet adequately understood. In the present work, a modeling framework is presented to simulate athermal, non-equilibrium plasma discharges in conjunction with low Mach number fluid dynamics at atmospheric pressure. The plasma and fluid species are treated as a two-fluid system exhibiting a few decades of length and time scales. The effect of the plasma dynamics on the fluid dynamics is devised via a body force treatment in the Navier-Stokes equations. Two different approaches of different degrees of fidelity are presented for modeling the plasma dynamics. The first approach, a phenomenological model, is based on a linearized force distribution approximating the discharge structure, and utilizing experimental guidance to deduce the empirical constants. A high fidelity approach is to model the plasma dynamics in a self-consistent manner using a first principle-based hydrodynamic plasma model. The atmospheric pressure regime of interest here enables us to employ local equilibrium assumptions, signifying efficient collisional energy exchange as against thermal heating from inelastic collision processes. The time scale ratios between convection, diffusion, and reaction/ionization mechanisms are O(107), making the system computationally stiff. To handle the stiffness, a sequential finite-volume operator-splitting algorithm capable of conserving space charge is developed; the approach can handle time

  6. Does exclusion of protest zeros and warm-glow bidders cause selection bias in Contingent Valuation?

    DEFF Research Database (Denmark)

    Grammatikopoulou, Ioanna; Olsen, Søren Bøye; Pouta, Eija

    A great issue of concern in valuation studies is whether respondents provide trustworthy and reliable answers conditional on the perceived information. Respondent may report either a higher than the true Willingness-To-Pay (WTP) due to warm glow or embedding effects or zero WTP which is lower than...... the true WTP due to protest behavior. We conduct a contingent valuation study to estimate the WTP for conserving a Natura 2000 wetland area in Greece. We find that 54% of the positive bidders exert warm glow motivations while 29% of all responses can be classified as protest zero bids. We employ three...

  7. Research progress in the study of atmospheric pressure glow barrier discharge

    Institute of Scientific and Technical Information of China (English)

    LI Xuechen; DONG Lifang; JIA Pengying

    2007-01-01

    Atmospheric pressure glow barrier discharge (APGBD) can operate at high pressure, and so vacuum device is not necessary. Furthermore, the produced plasma by APGBD has moderate electron temperature and density besides good uniformity. Therefore,APGBD has extensive potential applications in industry and has been becoming a hot issue in the research of low temperature plasma. In this paper, the main problems in the study of atmospheric pressure glow discharge generated by dielectric barrier discharge, including the experimental setup, judging criterion, discharging conditions, physical mechanisms, and parameter diagnoses, are discussed, and further research prospects of APGBD are proposed.

  8. Characteristics of liquid flow induced by atmospheric-pressure DC glow discharge in contact with liquid

    Science.gov (United States)

    Tochikubo, Fumiyoshi; Aoki, Takuya; Shirai, Naoki; Uchida, Satoshi

    2017-04-01

    In this work, we investigated the characteristics of liquid flow induced by atmospheric-pressure dc glow discharge in contact with a liquid. The spatiotemporal development of liquid flow was visualized by the schlieren method, and the temperature distribution was measured using microencapsulated thermotropic liquid crystal particles dispersed in a liquid. We confirmed the appearance of specific downward liquid flow immediately below the dc glow discharge. The characteristics of downward liquid flow were reproduced by fluid simulation considering a downward driving force at the plasma–liquid interface. Our results suggest that the probable driving force for the downward liquid flow was the momentum transfer of charged species at the liquid surface.

  9. A STUDY OF THE POLYMERIZATION MECHANISM OF ACETONITRILE IN GLOW DISCHARGE

    Institute of Scientific and Technical Information of China (English)

    YU Qingsong; YE Mu; LU Lizhen; CHEN Jie; WANG Fosong; Yoshihito Osada

    1988-01-01

    Plasma polymerization of acetonitrile was carried out by a capacitively coupled RF plasma apparatus with external electrodes under some different reaction conditions such as discharge power. By investigating the informations provided by the polymer deposition regularities, IR spectra and elementary analysis results,the polymerization mechanism of acetonitrile in glow discharge have been investigated. The results show that acetonitrile polymerized in glow discharge mainly through hydrogen detachment for initiation at lower energy levels and the role that opening C = N triple bond played in polymerization became more important at higher energy levels.

  10. Progress in the understanding of non-1D glow discharges: experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Derouard, J. [Laboratoire de Spectrometrie Physique (UA CNRS 08), Universite Joseph Fourier (Grenoble-I), BP 87, 38402 Saint Martin d`Heres (France); Pitchford, L. [Centre de Physique des Plasmas et Applications de Toulouse (UA CNRS 277), Universite Paul Sabatier, 31062 Toulouse (France)

    1996-03-01

    This contribution is a joint presentation on the structure of non unidimensional glow discharges experimentally observed using in particular optical diagnostics and predicted using self consistent numerical models. Results are presented concerning the effect of radial losses and electrode edges on the structure of DC and RF glow discharges, and the inititation phase of the breakdown in planar hollow cathode discharges. Most of the observed features of the discharges can be well reproduced by the models, which thus can be used to predict the effect of geometry on plasma devices and guide the optimization of their design. {copyright} {ital 1996 American Institute of Physics.}

  11. 110° C thermoluminescence glow peak of quartz – A brief review

    Indian Academy of Sciences (India)

    D K Koul

    2008-12-01

    The 110°C glow peak of quartz, though unstable at room temperature, has worked wonderfully in archaeology and retrospective dosimetry due to its pre-dose sensitization property. Various aspects of the peak, like its nature, defect centres involved, the impact of different stimuli and its application have been extensively studied. The main aims of this review are to (i) summarize briefly the work carried out on the various facets of this TL glow peak during the last four decades and (ii) identify the areas which need further attention in order to have a better understanding of the luminescence characteristics of this TL peak.

  12. A study of glow-discharge and permeation techniques for extraterrestrial oxygen beneficiation

    Science.gov (United States)

    Ash, R. L.; Wu, D.; Outlaw, R. A.

    1994-01-01

    Extraction of oxygen from Martian atmosphere and compression of lunar oxygen can utilize stabilized zirconia electrochemical pumps. Silver membranes can be used as electrodes to increase oxygen yield at relatively low temperatures. This study has investigated oxygen permeation through Ag 0.05Zr membranes with glow-discharge assisted disassociation. Data show that the overall process is controlled by bulk diffusion but the slow dissociative adsorption onto the surface limited the overall transport substantially. With glow-discharge assisted dissociation, an order of magnitude increase in oxygen throughput can be produced at relatively low temperatures (450-550C).

  13. Detrapping of tungsten nanoparticles in a direct-current argon glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Couëdel, L., E-mail: lenaic.couedel@univ-amu.fr; Kumar, K. Kishor; Arnas, C. [Laboratoire de Physique des Interactions Ioniques et Moléculaires, CNRS, Aix-Marseille Université, 13397 Marseille (France)

    2014-12-15

    Nanoparticles are grown from the sputtering of a tungsten cathode in a direct current argon glow discharge. Laser light scattering of a vertical laser sheet going through the plasma reveals that the dust particle cloud is compressed and pushed towards the anode during the discharge. Scanning electron microscopy images of substrates exposed to the plasma for given durations show that dust particles are continuously falling down on the anode during the discharge. These observations are explained by the fact that the electrostatic force at the negative glow-anode sheath boundary cannot balance the ion drag, gravity, and thermophoresis forces for particles of more than a few tens of nanometres in diameter.

  14. Short-term low-temperature glow discharge nitriding of 316L austenitic steel

    Directory of Open Access Journals (Sweden)

    T. Frączek

    2011-07-01

    Full Text Available The AISI 316L austenitic steel after glow discharge nitriding at temperature of T = 673 K and duration of τ=14,4 ks, for two different variants of specimen arrangement in the glow-discharge chamber was investigated. In order to assess the effectiveness of nitriding process, the surface layers profile analysis examination, surface hardness and hardness profile examination, the analysis of surface layer structures and corrosion resistance tests were performed. It has been found that application of a booster screen effects in a nitrogen diffusion depth increment into the 316L austenitic steel surface, what results in the surface layer thickness escalation.

  15. Thermoluminescence glow curve involving any extent of retrapping or any order of kinetics

    Indian Academy of Sciences (India)

    Jai Prakash

    2013-09-01

    Adirovitch set of equations has been modified to explain the mechanisms involved in thermoluminescence (TL) glow curve. A simple model is proposed which explains the occurrence of TL glow curve involving any extent of retrapping or any order of kinetics. It has been observed that the extents of recombination and simultaneous rewrapping decide the order of kinetics involved. TL decay parameters, order of kinetics and initial concentration of trapped electrons per unit volume are evaluated easily and conveniently. It has been observed that retrapping increases with increasing order of kinetics.

  16. Computerized glow curve deconvolution: the case of LiF TLD-100

    Energy Technology Data Exchange (ETDEWEB)

    Gartia, R.K.; Dorendrajit Singh, S.; Mazumdar, P.S. (Manipur Univ. (India). Dept. of Physics)

    1993-05-14

    It has been accepted by a large number of workers that the glow curve of LiF TLD (Thermoluminescent dosimetry)-100 can be described by thermoluminescence (TL) peaks following the Randall-Wilkins (RW) equation, even though the model fails to explain a number of experimental facts. A further simplification of the model is the Podgorsak-Moran-Cameron (PMC) approximation which is also in use. This paper points out the limitation of the PMC approximation in deconvoluting glow curves of LiF TLD-100. (author).

  17. East Asian observations of low-latitude aurora during the Carrington magnetic storm

    Science.gov (United States)

    Hayakawa, Hisashi; Iwahashi, Kiyomi; Tamazawa, Harufumi; Isobe, Hiroaki; Kataoka, Ryuho; Ebihara, Yusuke; Miyahara, Hiroko; Kawamura, Akito Davis; Shibata, Kazunari

    2016-10-01

    A magnetic storm around 1859 September 2, caused by a so-called Carrington flare, was the most intense in the history of modern scientific observations, and hence is considered to be a benchmark event concerning space weather. The magnetic storm caused worldwide observations of auroras, even at very low latitudes, such as Hawaii, Panama, or Santiago. Available magnetic-field measurements at Bombay, India, showed two peaks: the main was the Carrington event, which occurred in day time in East Asia; a second storm after the Carrington event occurred at night in East Asia. In this paper, we present results from surveys of aurora records in East Asia, which provide new information concerning the aurora activity of this important event. We found some new East Asian records of low-latitude aurora observations caused by a storm which occurred after the Carrington event. The size of the aurora belt of the second peak of the Carrington magnetic storm was even wider than that of usual low-latitude aurora events.

  18. East Asian Observations of Low Latitude Aurora during the Carrington Magnetic Storm

    CERN Document Server

    Hayakawa, Hisashi; Tamazawa, Harufumi; Isobe, Hiroaki; Kataoka, Ryuho; Ebihara, Yusuke; Miyahara, Hiroko; Kawamura, Akito Davis; Shibata, Kazunari

    2016-01-01

    The magnetic storm around 1859 September 2, caused by so-called Carrington flare, was the most intense in the history of modern scientific observations, and hence is considered to be the benchmark event for space weather. The magnetic storm caused worldwide observations of auroras even at very low latitudes such as Hawaii, Panama, or Santiago, and the available magnetic field measurement at Bombay, India, showed two peaks: the main was the Carrington event which occurred in day time in East Asia, and a second storm after the Carrington event which occurred at night in East Asia. In this paper, we present a result from surveys of aurora records in East Asia, which provides new information of the aurora activity of this important event. We found some new East Asian records of low latitude aurora observations caused by the storm which occurred after the Carrington event. The size of the aurora belt of the second peak of the Carrington magnetic storm was even wider than usual low-latitude aurora events.

  19. Evidence that Aurora B is implicated in spindle checkpoint signalling independently of error correction.

    Science.gov (United States)

    Santaguida, Stefano; Vernieri, Claudio; Villa, Fabrizio; Ciliberto, Andrea; Musacchio, Andrea

    2011-04-20

    Fidelity of chromosome segregation is ensured by a tension-dependent error correction system that prevents stabilization of incorrect chromosome-microtubule attachments. Unattached or incorrectly attached chromosomes also activate the spindle assembly checkpoint, thus delaying mitotic exit until all chromosomes are bioriented. The Aurora B kinase is widely recognized as a component of error correction. Conversely, its role in the checkpoint is controversial. Here, we report an analysis of the role of Aurora B in the spindle checkpoint under conditions believed to uncouple the effects of Aurora B inhibition on the checkpoint from those on error correction. Partial inhibition of several checkpoint and kinetochore components, including Mps1 and Ndc80, strongly synergizes with inhibition of Aurora B activity and dramatically affects the ability of cells to arrest in mitosis in the presence of spindle poisons. Thus, Aurora B might contribute to spindle checkpoint signalling independently of error correction. Our results support a model in which Aurora B is at the apex of a signalling pyramid whose sensory apparatus promotes the concomitant activation of error correction and checkpoint signalling pathways.

  20. Ipl1/Aurora-B is necessary for kinetochore restructuring in meiosis I in Saccharomyces cerevisiae.

    Science.gov (United States)

    Meyer, Régis E; Chuong, Hoa H; Hild, Marrett; Hansen, Christina L; Kinter, Michael; Dawson, Dean S

    2015-09-01

    In mitosis, the centromeres of sister chromosomes are pulled toward opposite poles of the spindle. In meiosis I, the opposite is true: the sister centromeres move together to the same pole, and the homologous chromosomes are pulled apart. This change in segregation patterns demands that between the final mitosis preceding meiosis and the first meiotic division, the kinetochores must be restructured. In budding yeast, unlike mammals, kinetochores are largely stable throughout the mitotic cycle. In contrast, previous work with budding and fission yeast showed that some outer kinetochore proteins are lost in early meiosis. We use quantitative mass spectrometry methods and imaging approaches to explore the kinetochore restructuring process that occurs in meiosis I in budding yeast. The Ndc80 outer kinetochore complex, but not other subcomplexes, is shed upon meiotic entry. This shedding is regulated by the conserved protein kinase Ipl1/Aurora-B and promotes the subsequent assembly of a kinetochore that will confer meiosis-specific segregation patterns on the chromosome.

  1. Discovery of novel inhibitors of Aurora kinases with indazole scaffold: In silico fragment-based and knowledge-based drug design.

    Science.gov (United States)

    Chang, Chun-Feng; Lin, Wen-Hsing; Ke, Yi-Yu; Lin, Yih-Shyan; Wang, Wen-Chieh; Chen, Chun-Hwa; Kuo, Po-Chu; Hsu, John T A; Uang, Biing-Jiun; Hsieh, Hsing-Pang

    2016-11-29

    Aurora kinases have emerged as important anticancer targets so that there are several inhibitors have advanced into clinical study. Herein, we identified novel indazole derivatives as potent Aurora kinases inhibitors by utilizing in silico fragment-based approach and knowledge-based drug design. After intensive hit-to-lead optimization, compounds 17 (dual Aurora A and B), 21 (Aurora B selective) and 30 (Aurora A selective) possessed indazole privileged scaffold with different substituents, which provide sub-type kinase selectivity. Computational modeling helps in understanding that the isoform selectivity could be targeted specific residue in the Aurora kinase binding pocket in particular targeting residues Arg220, Thr217 or Glu177.

  2. The thermoluminescence glow curve and the deconvoluted glow peak characteristics of erbium doped silica fiber exposed to 70-130 kVp x-rays.

    Science.gov (United States)

    Alawiah, A; Bauk, S; Marashdeh, M W; Nazura, M Z N; Abdul-Rashid, H A; Yusoff, Z; Gieszczyk, W; Noramaliza, M N; Adikan, F R Mahamd; Mahdiraji, G A; Tamchek, N; Muhd-Yassin, S Z; Mat-Sharif, K A; Zulkifli, M I; Omar, N; Wan Abdullah, W S; Bradley, D A

    2015-10-01

    In regard to thermoluminescence (TL) applied to dosimetry, in recent times a number of researchers have explored the role of optical fibers for radiation detection and measurement. Many of the studies have focused on the specific dopant concentration, the type of dopant and the fiber core diameter, all key dependencies in producing significant increase in the sensitivity of such fibers. At doses of less than 1 Gy none of these investigations have addressed the relationship between dose response and TL glow peak behavior of erbium (Er)-doped silica cylindrical fibers (CF). For x-rays obtained at accelerating potentials from 70 to 130 kVp, delivering doses of between 0.1 and 0.7 Gy, present study explores the issue of dose response, special attention being paid to determination of the kinetic parameters and dosimetric peak properties of Er-doped CF. The effect of dose response on the kinetic parameters of the glow peak has been compared against other fiber types, revealing previously misunderstood connections between kinetic parameters and radiation dose. Within the investigated dose range there was an absence of supralinearity of response of the Er-doped silica CF, instead sub-linear response being observed. Detailed examination of glow peak response and kinetic parameters has thus been shown to shed new light of the rarely acknowledged issue of the limitation of TL kinetic model and sub-linear dose response of Er-doped silica CF.

  3. Narcís Vidal i Campderros i l'aurora boreal observada a Barcelona el 1839

    OpenAIRE

    Barca Salom, Francesc Xavier

    2011-01-01

    The aurora borealis is an intense light in latitudes near the poles. It is known as the aurora australis in the southern hemisphere. An aurora is arch-shaped and undergoes intense colour changes. It is often accompanied by a sound resembling that of silk being rubbed and emits an odour characteristic of ozone. Although an aurora usually occurs in high latitudes, it sometimes takes place in lower latitudes. This paper focuses on the report made by Narcís Vidal i Campderrós (1792...

  4. Specific small-molecule activator of Aurora kinase A induces autophosphorylation in a cell-free system.

    Science.gov (United States)

    Kishore, A Hari; Vedamurthy, B M; Mantelingu, K; Agrawal, Shipra; Reddy, B A Ashok; Roy, Siddhartha; Rangappa, K S; Kundu, Tapas K

    2008-02-28

    Aurora kinases are essential for chromosomal segregation and cell division and thereby important for maintaining the proper genomic integrity. There are three classes of aurora kinases in humans: A, B, and C. Aurora kinase A is frequently overexpressed in various cancers. The link of the overexpression and tumorigenesis is yet to be understood. By employing virtual screening, we have found that anacardic acid, a pentadecane aliphatic chain containing hydroxylcarboxylic acid, from cashew nut shell liquid could be docked in Aurora kinases A and B. Remarkably, we found that anacardic acid could potently activate the Aurora kinase A mediated phosphorylation of histone H3, but at a similar concentration the activity of aurora kinase B remained unaffected in vitro. Mechanistically, anacardic acid induces the structural changes and also the autophosphorylation of the aurora kinase A to enhance the enzyme activity. This data thus indicate anacardic acid as the first small-molecule activator of Aurora kinase, which could be highly useful for probing the function of hyperactive (overexpressed) Aurora kinase A.

  5. A statistical study of dayside diffuse aurora observed at Yellow River Station in Ny-Ålesund, Svalbard

    Science.gov (United States)

    Han, D.; Hu, Z.; Hu, H.; Yang, H.; Huang, D. H.; Chen, X.

    2014-12-01

    Chinese Yellow River Station (YRS), at Ny-Alesund, Svalbard is one of the few stations that can make longtime optical auroral observation at the cusp latitude in the dayside during the boreal winter season on the Earth. Since November 2003, an optical observation system consisting of three identical all-sky imagers supplied with the narrow band filters centered at 427.8, 557.5 and 630.0nm, has been installed at YRS, and the continuous observations providing us with an unprecedented opportunity to investigate some new properties of dayside aurora. Optical diffuse auroras are normally observed at the sub-aurora latitude in nightside on the ground. However, by using 7-year continuous observations obtained at YRS, we found that the diffuse auroras are very frequently observed on the dayside at the high latitude, i.e., near the cusp. We classified the dayside diffuse aurora into four primary categories. They are (1) Veiling Diffuse Aurora, which has no obvious morphological structure and clear boundaries, sometimes likes a thick cloud cover the entire sky, (2) Patch Diffuse Aurora, which is an aurora patch normally in ~10-100km in width and usually owns pulsating property; (3) Diffuse Arcs, which looks like an arc but is apparently different from the discrete auroral arcs in morphology, and (4) Pulsating Aurora, occurring with sparkling forms. We statistical studied how the occurrence of the four types of dayside diffuse auroras depends on the local time, magnetic activity, and solar wind conditions. We found that the occurrence of each type of dayside diffuse aurora shows a unimodal distribution with magnetic local time and their peaks are mostly appeared near the magnetic local noon. We also noted that ~92.2% of the dayside diffuse auroras is observed under low magnetic activity, i.e., Kp ≤ 3, and the dayside diffuse auroras prefer to be observed under IMF By0. Although previous studies suggested that the dayside diffuse aurora should be caused by wave scattering of

  6. Endotoxin removal by radio frequency gas plasma (glow discharge)

    Science.gov (United States)

    Poon, Angela

    2011-12-01

    Contaminants remaining on implantable medical devices, even following sterilization, include dangerous fever-causing residues of the outer lipopolysaccharide-rich membranes of Gram-negative bacteria such as the common gut microorganism E. coli. The conventional method for endotoxin removal is by Food & Drug Administration (FDA)-recommended dry-heat depyrogenation at 250°C for at least 45 minutes, an excessively time-consuming high-temperature technique not suitable for low-melting or heat-distortable biomaterials. This investigation evaluated the mechanism by which E. coli endotoxin contamination can be eliminated from surfaces during ambient temperature single 3-minute to cumulative 15-minute exposures to radio-frequency glow discharge (RFGD)-generated residual room air plasmas activated at 0.1-0.2 torr in a 35MHz electrodeless chamber. The main analytical technique for retained pyrogenic bio-activity was the Kinetic Chromogenic Limulus Amebocyte Lysate (LAL) Assay, sufficiently sensitive to document compliance with FDA-required Endotoxin Unit (EU) titers less than 20 EU per medical device by optical detection of enzymatic color development corresponding to water extracts of each device. The main analytical technique for identification of chemical compositions, amounts, and changes during sequential reference Endotoxin additions and subsequent RFGD-treatment removals from infrared (IR)-transparent germanium (Ge) prisms was Multiple Attenuated Internal Reflection (MAIR) infrared spectroscopy sensitive to even monolayer amounts of retained bio-contaminant. KimaxRTM 60 mm x 15 mm and 50mm x 15mm laboratory glass dishes and germanium internal reflection prisms were inoculated with E. coli bacterial endotoxin water suspensions at increments of 0.005, 0.05, 0.5, and 5 EU, and characterized by MAIR-IR spectroscopy of the dried residues on the Ge prisms and LAL Assay of sterile water extracts from both glass and Ge specimens. The Ge prism MAIR-IR measurements were

  7. Accounting protesting and warm glow bidding in Contingent Valuation surveys considering the management of environmental goods

    DEFF Research Database (Denmark)

    Grammatikopoulou, Ioanna; Olsen, Søren Bøye

    2013-01-01

    Based on a Contingent Valuation survey aiming to reveal the willingness to pay (WTP) for conservation of a wetland area in Greece, we show how protest and warm glow motives can be taken into account when modeling WTP. In a sample of more than 300 respondents, we find that 54% of the positive bids...

  8. An efficient model to simulate stable glow corona discharges and their transition into streamers

    Science.gov (United States)

    Liu, Lipeng; Becerra, Marley

    2017-03-01

    A computationally efficient model to evaluate stable glow corona discharges and their transition into streamers is proposed. The simplified physical model referred to as the SPM is based on the classic hydrodynamic model of charge particles and a quasi-steady state approximation for electrons. The solution follows a two-step segregated procedure, which solves sequentially the stationary continuity equation for electrons and then time-dependent continuity equations for ions. The validity of using the SPM to simulate glow corona discharges and their transition into streamers is demonstrated by performing comparisons with a fully coupled physical model (FPM) and with experimental data available in the literature for air under atmospheric conditions. It is shown that the SPM can obtain estimates similar to those calculated with the FPM and those measured in experiments but using significantly less computation time. Since the proposed model simulates efficiently the ionization layer without prior knowledge of the surface electric field or the discharge current, it is a computationally efficient alternative to calculations of glow corona discharges based on Kaptzov’s approximation (KAM). The model can also be employed to efficiently calculate the conditions for the transition of glow corona into streamers, overcoming the limitations of KAM to provide such estimates.

  9. Qualitative gas temperature distribution in positive DC glow corona using spectral image processing in atmospheric air

    Science.gov (United States)

    Matsumoto, Takao; Inada, Yoichi; Shimizu, Daisuke; Izawa, Yasuji; Nishijima, Kiyoto

    2015-01-01

    An experimental method of determining a qualitative two-dimensional image of the gas temperature in stationary atmospheric nonthermal plasma by spectral image processing was presented. In the experiment, a steady-state glow corona discharge was generated by applying a positive DC voltage to a rod-plane electrode in synthetic air. The changes in the gas temperature distribution due to the amplitude of applied voltage and the ambient gas pressure were investigated. Spectral images of a positive DC glow corona were taken using a gated ICCD camera with ultranarrow band-pass filters, corresponding to the head and tail of a N2 second positive system band (0-2). The qualitative gas temperature was obtained from the emission intensity ratio between the head and tail of the N2 second positive system band (0-2). From the results, we confirmed that the gas temperature and its distribution of a positive DC glow corona increased with increasing applied voltage. In particular, just before the sparkover voltage, a distinctly high temperature region was formed in the positive DC glow at the tip of the rod electrode. In addition, the gas temperature decreased and its distribution spread diffusely with decreasing ambient gas pressure.

  10. A Study on Water Treatment Induced by Plasma with Contact Glow Discharge Electrolysis

    Institute of Scientific and Technical Information of China (English)

    胡中爱; 王晓艳; 高锦章; 邓华陵; 侯经国; 卢小泉; 康敬万

    2001-01-01

    Oxidative degradation of eight kinds of dyes induced by plasma in aqueous solution was investigated with contact glow discharge electrolysis (CGDE). It has been demonstrated that these eight dyes underwent degradation in CGDE, where Fe2+ could be utilised to raise the efficiency of degradation of dyes.

  11. The multisensor payload 'Structura' for the observation of atmospheric night glows from the ISS board

    Science.gov (United States)

    Krot, Yury; Beliaev, Boris; Katkovsky, Leonid

    2016-10-01

    Aerospace Research Department of the Institute of Applied Physical Problems at Belarusian State University has developed a prototype of the optical payload intended for a space experiment on the ISS board. The prototype includes four optical modules for the night glows observation, in particular spatial-brightness and spectral characteristics in the altitude range of 80-320 km. Objects of the interest are emitting top layers of the atmosphere including exited OH radicals, atomic and molecular oxygen and sodium layers. The goal of the space experiment is a research of night glows over different regions of the Earth and a connection with natural disasters like earthquakes, cyclones, etc. Two optical modules for spatial distribution of atomic oxygen layers along the altitude consist of input lenses, spectral interferential filters and line CCD detectors. The optical module for registration of exited OH radical emissions is formed from CCD array spectrometer. The payload includes also a panchromatic (400-900 nm) high sensitive imaging camera for observing of the glows general picture. The optical modules of the prototype have been tested and general optical characteristics were determined in laboratory conditions. A solution of an astigmatism reducing of a concave diffraction grating and a method of the second diffraction order correction were applied and improved spectrometer's optical characteristics. Laboratory equipment and software were developed to imitate a dynamic scene of the night glows in laboratory conditions including an imitation of linear spectra and the spatial distribution of emissions.

  12. Drift-diffusion model of normal glow discharge in an axial magnetic field

    Science.gov (United States)

    Surzhikov, S. T.

    2016-12-01

    A two-dimensional axisymmetrical computing model is formulated with using of which the mathematical modeling of the normal glow discharge in molecular hydrogen is fulfilled in an axial magnetic field with the induction B = 0.1 T in the pressure range p = 1.25-5 Torr and the current-source electromotive force E = 1-3 kV.

  13. Quantitative Analysis on Carbon Migration in Double-Glow Discharge Plasma Surface Alloying Process

    Institute of Scientific and Technical Information of China (English)

    ZHANGZhen-xia; WANGCong-zeng; ZHANGWen-quan; SUXue-kuan

    2004-01-01

    Carbon migration is of great significance in double-glow discharge plasma surface alloying process, but literature of quantitative analysis about carbon migration is relatively scarce. In this paper differential equations of the carbon and metal concentration distribution were established. By means of differential equations carbon migration was described and a numerical solution was acquired. The computational results fit the experiment results quite well.

  14. Evaluation of trapping parameter of quartz by deconvolution of the glow curves

    Energy Technology Data Exchange (ETDEWEB)

    Gartia, R.K. [Department of Physics, Manipur University, Imphal 795001 (India); Singh, L. Lovedy, E-mail: lovedyo1@yahoo.co.in [Department of Physics, Manipur University, Imphal 795001 (India)

    2011-08-15

    The glow curves of natural quartz excited with different doses of {beta}-irradiation have been subjected to Computerized Glow Curve Deconvolution (CGCD) in the kinetic formalism. The location of the constituent peaks, which are as many as eleven in the temperature region of 27-575 deg. C, has been ascertained by resorting to the second order derivative plot of the glow curve. Not only figure of merit (FOM) but {chi}{sup 2}-test has also been taken as a criterion for the acceptance of goodness of fit. CGCD analysis reveals that the frequency factor of quartz is in the range of 1.50 {+-} 0.26 x 10{sup 11} sec{sup -1}. This analysis lead to the conclusion that the trapping levels of quartz can be approximated by the Urbach's relation E = 27kT{sub m} where T{sub m} is the temperature at the maximum intensity. - Highlights: > Glow curves of natural and beta-irradiated quartz in the temperature range from room temperature to 573 deg. C is analysed. > Frequency factor of quartz is in the range of 1.50 {+-} 0.26 x 10{sup 11} sec{sup -1}. > Trapping levels of quartz can be approximated by the Urbach's relation E = 27kT{sub m}.

  15. Characteristics of north jovian aurora from STIS FUV spectral images

    Science.gov (United States)

    Gustin, J.; Grodent, D.; Ray, L. C.; Bonfond, B.; Bunce, E. J.; Nichols, J. D.; Ozak, N.

    2016-04-01

    We analyzed two observations obtained in Jan. 2013, consisting of spatial scans of the jovian north ultraviolet aurora with the HST Space Telescope Imaging Spectrograph (STIS) in the spectroscopic mode. The color ratio (CR) method, which relates the wavelength-dependent absorption of the FUV spectra to the mean energy of the precipitating electrons, allowed us to determine important characteristics of the entire auroral region. The results show that the spatial distribution of the precipitating electron energy is far from uniform. The morning main emission arc is associated with mean energies of around 265 keV, the afternoon main emission (kink region) has energies near 105 keV, while the 'flare' emissions poleward of the main oval are characterized by electrons in the 50-85 keV range. A small scale structure observed in the discontinuity region is related to electrons of 232 keV and the Ganymede footprint shows energies of 157 keV. Interestingly, each specific region shows very similar behavior for the two separate observations. The Io footprint shows a weak but undeniable hydrocarbon absorption, which is not consistent with altitudes of the Io emission profiles (∼900 km relative to the 1 bar level) determined from HST-ACS observations. An upward shift of the hydrocarbon homopause of at least 100 km is required to reconcile the high altitude of the emission and hydrocarbon absorption. The relationship between the energy fluxes and the electron energies has been compared to curves obtained from Knight's theory of field-aligned currents. Assuming a fixed electron temperature of 2.5 keV, an electron source population density of ∼800 m-3 and ∼2400 m-3 is obtained for the morning main emission and kink regions, respectively. Magnetospheric electron densities are lowered for the morning main emission (∼600 m-3) if the relativistic version of Knight's theory is applied. Lyman and Werner H2 emission profiles, resulting from secondary electrons produced by

  16. AURORA BOREALIS: a polar-dedicated European Research Platform

    Science.gov (United States)

    Wolff-Boenisch, Bonnie; Egerton, Paul; Thiede, Joern; Roberto, Azzolini; Lembke-Jene, Lester

    2010-05-01

    Polar research and in particular the properties of northern and southern high latitude oceans are currently a subject of intense scientific debate and investigations, because they are subject to rapid and dramatic climatic variations. Polar regions react more rapidly and intensively to global change than other regions of the earth. A shrinking of the Arctic sea-ice cover, potentially leading to an opening of sea passages to the north of North America and Eurasia, on the long to a "blue" Arctic Ocean would additionally have a strong impact on transport, commerce and tourism bearing potential risk for humans and complex ecosystems in the future. In spite of their critical role processes and feedbacks, especially in winter but not exclusively, are virtually unknown: The Arctic Ocean for example, it is the only basin of the world's oceans that has essentially not been sampled by the drill ships of the Deep-Sea Drilling Project (DSDP) or the Ocean Drilling Program (ODP) and its long-term environmental history and tectonic structure is therefore poorly known. Exceptions are the ODP Leg 151 and the more recent very successful ACEX-expedition of the Integrated Ocean Drilling Program (IODP) in 2004. To help to address the most pressing questions regarding climate change and related processes, a Pan-European initiative in the field of Earth system science has been put in place: AURORA BOREALIS is the largest environmental research infrastructure on the ESFRI roadmap of the European Community. AURORA BOREALIS is a very powerful research icebreaker, which will enable year-round operations in the Arctic and the Antarctic as well as in the adjacent ocean basins. Equipped with its drilling rig, the vessel is also capable to explore the presently completely unknown Arctic deep-sea floor. Last but not least, the ship is a floating observatory and mobile monitoring platform that permits to measure on a long-term basis comprehensive time series in all research fields relevant to

  17. The Aurora Kinase in Trypanosoma brucei plays distinctive roles in metaphase-anaphase transition and cytokinetic initiation.

    Directory of Open Access Journals (Sweden)

    Ziyin Li

    2009-09-01

    Full Text Available Aurora B kinase is an essential regulator of chromosome segregation with the action well characterized in eukaryotes. It is also implicated in cytokinesis, but the detailed mechanism remains less clear, partly due to the difficulty in separating the latter from the former function in a growing cell. A chemical genetic approach with an inhibitor of the enzyme added to a synchronized cell population at different stages of the cell cycle would probably solve this problem. In the deeply branched parasitic protozoan Trypanosoma brucei, an Aurora B homolog, TbAUK1, was found to control both chromosome segregation and cytokinetic initiation by evidence from RNAi and dominant negative mutation. To clearly separate these two functions, VX-680, an inhibitor of TbAUK1, was added to a synchronized T. brucei procyclic cell population at different cell cycle stages. The unique trans-localization pattern of the chromosomal passenger complex (CPC, consisting of TbAUK1 and two novel proteins TbCPC1 and TbCPC2, was monitored during mitosis and cytokinesis by following the migration of the proteins tagged with enhanced yellow fluorescence protein in live cells with time-lapse video microscopy. Inhibition of TbAUK1 function in S-phase, prophase or metaphase invariably arrests the cells in the metaphase, suggesting an action of TbAUK1 in promoting metaphase-anaphase transition. TbAUK1 inhibition in anaphase does not affect mitotic exit, but prevents trans-localization of the CPC from the spindle midzone to the anterior tip of the new flagellum attachment zone for cytokinetic initiation. The CPC in the midzone is dispersed back to the two segregated nuclei, while cytokinesis is inhibited. In and beyond telophase, TbAUK1 inhibition has no effect on the progression of cytokinesis or the subsequent G1, S and G2 phases until a new metaphase is attained. There are thus two clearly distinct points of TbAUK1 action in T. brucei: the metaphase-anaphase transition and

  18. Characterization of cadmium uptake by the water lily Nymphaea aurora.

    Science.gov (United States)

    Schor-Fumbarov, Tamar; Keilin, Zvika; Tel-Or, Elisha

    2003-01-01

    This study characterizes cadmium (Cd) uptake by the waterlily Nymphaea aurora, (Nymphaeaceae) in two systems: a model hydroponic Cd solution and heavily polluted sludge from two sites in Israel. The uptake of Cd from hydroponic solution resulted in Cd storage in petioles and laminae of Nymphaea, as well as in the roots. The pH of the solution affected Cd solubility and availability, with pH 5.5 yielding maximum Cd content in the plant (140 mg Cd per g DW). Cd uptake was reduced by the addition of EDTA to the hydroponic growth medium, although EDTA enhanced heavy metal uptake by terrestrial plants. Nymphaea efficiently reduced the concentration of Cd in heavy metal polluted urban and industrial sludge and the amount of Cd uptake was enhanced by the addition of KCl to the sludge and by adjustment of the pH to 5.5. The inherent growth patterns of Nymphaea plants allowed Cd uptake by the shoot and root, and resulted in maximum contact between the various plant parts and the growth media. Thus, Nymphaea has potential as an optimal, highly effective phytoremediation tool for the removal of Cd from polluted waste sources.

  19. A study of Jupiter's aurorae with XMM-Newton

    CERN Document Server

    Branduardi-Raymont, G; Elsner, R F; Gladstone, G R; Ramsay, G; Rodríguez, P; Soria, R; Cravens, T E

    2006-01-01

    We present a detailed analysis of Jupiter's X-ray (0.2-10 keV) auroral emissions as observed by XMM-Newton in Nov. 2003 and compare it with that of an Apr. 2003 observation. We discover the existence of an electron bremsstrahlung component in the aurorae, which accounts for essentially all the X-ray flux above 2 keV: its presence had been predicted but never detected for lack of sensitivity of previous X-ray missions. This bremsstrahlung component varied significantly in strength and spectral shape over the 3.5 days covered by the Nov. 2003 observation, displaying substantial hardening of the spectrum with increasing flux. This variability may be linked to the strong solar activity taking place at the time, and may be induced by changes in the acceleration mechanisms inside Jupiter's magnetosphere. As in Apr. 2003, the auroral spectra below 2 keV are best fitted by a superposition of line emission most likely originating from ion charge exchange, with OVII playing the dominant role. We still cannot resolve co...

  20. Cosmic ray secular variations in terrestrial records and aurorae

    Science.gov (United States)

    Attolini, M. R.; Castagnoli, G. C.; Bonino, G.; Galli, M.; Nanni, T.

    1985-01-01

    The rediscovery that the Sun and the solar wind can undergo important changes on historical time scales has brought into question the stability of the cyclic behavior of past time series of solar and solar-terrestrial origin. It was found by Vector Fourier analysis that the solar 11 year cycle is present in the series of 10Be, delta 180, in ice cores and of thermoluminescence (TL) in sea sediments during the last Millennia with a frequency modulation, related to the Sun behavior, as tested by comparison with the Sunspot number R sub z series. It was shown that the cyclogram of the series of yearly Aurorae from 1721 to 1979 linear-regression-corrected-for-R sub z is straight for the periodicity zeta=11,1y, which indicates that such periodicity is constant in time corresponding to the only line present in the 11y band. The maxima of this component appear at the same time together with the high speed solar wind streams taking place in coronal holes situated in high heliolatitudes. It is evidenced that the 11 year cycle has undergone frequency oscillations on a time scale of two centuries, although it is very difficult to determine the periodicities with high accuracy.

  1. Aurora 7 the Mercury space flight of M. Scott Carpenter

    CERN Document Server

    Burgess, Colin

    2016-01-01

    TO A NATION enthralled by the heroic exploits of the Mercury astronauts, the launch of Lt. Cmdr. Scott Carpenter on NASA’s second orbital space flight was a renewed cause for pride, jubilation and celebration. Within hours, that excitement had given way to stunned disbelief and anxiety as shaken broadcasters began preparing the American public for the very real possibility that an American astronaut and his spacecraft may have been lost at sea. In fact, it had been a very close call. Completely out of fuel and forced to manually guide Aurora 7 through the frightening inferno of re-entry, Carpenter brought the Mercury spacecraft down to a safe splashdown in the ocean. In doing so, he controversially overshot the intended landing zone. Despite his efforts, Carpenter’s performance on the MA-7 mission was later derided by powerful figures within NASA. He would never fly into space again. Taking temporary leave of NASA, Carpenter participated in the U.S. Navy’s pioneering Sealab program. For a record 30 days...

  2. Ezekiel and the Northern Lights: Biblical aurora seems plausible

    Science.gov (United States)

    Siscoe, George L.; Silverman, Samuel M.; Siebert, Keith D.

    Auroral specialists have suggested that in the Bible's Old Testament book of Ezekiel, the opening vision of a "storm cloud out of the north" depicts imagery inspired by a low-latitude auroral display [Link, 1967; Eather, 1980; Silverman, 1998]. Naturally, other interpretations have been suggested, including a true epiphany, a sandstorm, a thunderstorm, a tornado, a solar halo, a hallucination, and a UFO. Biblical scholars place the site of the Ezekiel's vision about 100 km south of Babylon near Nippur, latitude ˜32°, longitude ˜45°, and the date is within a year or two of 593 B.C., or about 2600 years ago.An auroral interpretation of the vision is subject to possible refutation due to several geophysical considerations. Can auroras be seen at Ezekiel's latitude? More important, can they reach a coronal stage of development, which is what the vision requires? Was the tilt of the dipole axis favorable? Was the general level of solar activity favorable? And finally, What effect does a larger dipole moment in Ezekiel's time have on the question? All but the last question could have been answered on the basis of geophysical data a decade ago or earlier.

  3. Research of the Effects of Electron Focused Electric Field upon an Enhanced Glow Discharge Plasma Ion Implantation

    Institute of Scientific and Technical Information of China (English)

    LI Liu-he; WU Yong-qin; ZHANG Yan-hua; CAI Xun; CHU Paul K

    2004-01-01

    A new Enhanced Glow Discharge Plasma Ion Implantation methods are introduced, in which the plasma are produced by the self glow discharge excitated by high negative voltage bias. The electric field is designed to a electron focusing mode by using a small area hollow anode and a large area sample holder cathode. The pattern of equipotentials of the electric field are calculated through finite-element method. By using the special electron-focusing field, the self glow discharge are enhanced and provide denser ions to implanted into the substrate.

  4. Composition dependence of glow peak temperature in KCl{sub 1-x}Br{sub x} doped with divalent cations

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Salas, R [Departamento de Investigacion en FIsica, Universidad de Sonora, Apartado Postal 5-088 Hermosillo, Sonora, 83190 (Mexico); Aceves, R [Departamento de Investigacion en FIsica, Universidad de Sonora, Apartado Postal 5-088 Hermosillo, Sonora, 83190 (Mexico); RodrIguez-Mijangos, R [Departamento de Investigacion en FIsica, Universidad de Sonora, Apartado Postal 5-088 Hermosillo, Sonora, 83190 (Mexico); Riveros, H G [Instituto de FIsica, UNAM, Apartado Postal 20/364, Mexico, DF 01000, Mexico (Mexico); Duarte, C [Departamento de GeologIa, Universidad de Sonora, Rosales y Boulevard Luis E, Hermosillo, Sonora, 83000 (Mexico)

    2004-01-28

    Thermoluminescence measurements of {beta}-irradiated Eu{sup 2+} - and Ca{sup 2+} - doped KCl{sub 1-x}KBr{sub x} solid solutions excited at room temperature have been carried out to identify the effect of composition on the glow peaks. A typical glow peak has been distinguished for each composition. A linear dependence of its temperature on the composition x has been found. These results indicate that for divalent impurity-doped alkali halide solid solutions these glow peak temperatures are mostly dependent on the lattice constant of the host than on the size of the anion or impurity cation.

  5. Urochordate ascidians possess a single isoform of Aurora kinase that localizes to the midbody via TPX2 in eggs and cleavage stage embryos.

    Directory of Open Access Journals (Sweden)

    Celine Hebras

    Full Text Available Aurora kinases are key proteins found throughout the eukaryotes that control mitotic progression. Vertebrate Aurora-A and B kinases are thought to have evolved from a single Aurora-kinase isoform closest to that found in present day urochordates. In urochordate ascidians Aurora binds both TPX2 (a vertebrate AURKA partner and INCENP (a vertebrate AURKB partner and localizes to centrosomes and spindle microtubules as well as chromosomes and midbody during both meiosis and mitosis. Ascidian Aurora also displays this localization pattern during mitosis in echinoderms, strengthening the idea that non-vertebrate deuterostomes such as the urochordates and echinoderms possess a single form of Aurora kinase that has properties of vertebrate Aurora-kinase A and B. In the ascidian, TPX2 localizes to the centrosome and the spindle poles also as in vertebrates. However, we were surprised to find that TPX2 also localized strongly to the midbody in ascidian eggs and embryos. We thus examined more closely Aurora localization to the midbody by creating two separate point mutations of ascidian Aurora predicted to perturb binding to TPX2. Both forms of mutated Aurora behaved as predicted: neither localized to spindle poles where TPX2 is enriched. Interestingly, neither form of mutated Aurora localized to the midbody where TPX2 is also enriched, suggesting that ascidian Aurora midbody localization required TPX2 binding in ascidians. Functional analysis revealed that inhibition of Aurora kinase with a pharmacological inhibitor or with a dominant negative kinase dead form of Aurora caused cytokinesis failure and perturbed midbody formation during polar body extrusion. Our data support the view that vertebrate Aurora-A and B kinases evolved from a single non-vertebrate deuterostome ancestor. Moreover, since TPX2 localizes to the midbody in ascidian eggs and cleavage stage embryos it may be worthwhile re-assessing whether Aurora A kinase or TPX2 localize to the midbody

  6. Validation of Aurora Solar Inc.'s Envision Software Capabilities

    Energy Technology Data Exchange (ETDEWEB)

    2017-04-03

    As part of the Department of Energy's SunShot Incubator program, Aurora has worked to develop a web-based application that quickly and precisely calculates the solar potential of a building's roof. The Aurora Envision platform utilizes Google StreetView photos as a basis for measuring roof slope and linear measurements of determining the proper inputs into an eventual shade model. The stated accuracy by Aurora Solar to be tested is lengths within 1.5 feet and slope measurements within 5 degrees. The National Renewable Energy Laboratory (NREL), in partnership with Aurora and supported by the U.S. Department of Energy's (DOE) SunShot Technology to Market Incubator program, independently verified the accuracy of Aurora's Envision measurements on 15 unique roofs throughout the Denver, Colorado region. NREL measured 60 measurements: 27 of 28 slope measurements were within the stated accuracy, 32 of 32 distance measurements were within the stated accuracy.

  7. Aurora Candidates from the Chronicle of Q\\={i}ng Dynasty in Several Degrees of Relevance

    CERN Document Server

    Kawamura, Akito D; Tamazawa, Harufumi; Miyahara, Hiroko; Isobe, Hiroaki

    2016-01-01

    We present the result of the survey of sunspots and auroras in ${\\it Q\\bar{\\imath}ngsh\\check{\\imath}ga\\check{o}}$, the draft chronicle of ${\\it Q\\bar{\\imath}ng}$ dynasty, for the period of 1559-1912 CE, as a sequel of the series of works surveying historical sunspot and aurora records, and providing online data to the scientific community regarding the attained results. In total of this ${\\it Q\\bar{\\imath}ngsh\\check{\\imath}ga\\check{o}}$ survey, we found 111 records of night-sky luminous events with the keywords such as vapor (${\\it q\\grave{\\imath}}$), cloud (${\\it y\\acute{u}n}$), and light (${\\it gu\\bar{a}ng}$), which may indicate auroras as well as some other phenomena. Similarly keyword survey for sunspots were done, but no sunspot record was found. In comparison with the aurora records in the western world, we found 14 of the 111 records have a corresponding record of simultaneous observation in the western world and hence are very likely to be aurora. In order to investigate the likeliness of the rest of ...

  8. Benzimidazole-Based Quinazolines: In Vitro Evaluation, Quantitative Structure-Activity Relationship, and Molecular Modeling as Aurora Kinase Inhibitors.

    Science.gov (United States)

    Sharma, Alka; Luxami, Vijay; Saxena, Sanjai; Paul, Kamaldeep

    2016-03-01

    A series of benzimidazole-based quinazoline derivatives with different substitutions of primary and secondary amines at the C2 position (1-12) were evaluated for their Aurora kinase inhibitory activities. All compounds except for 3 and 6 showed good activity against Aurora kinase inhibitors, with IC50 values in the range of 0.035-0.532 μM. The ligand efficiency (LE) of the compounds with Aurora A kinase was also determined. The structure-activity relationship and the quantitative structure-activity relationship revealed that the Aurora inhibitory activities of these derivatives primarily depend on the different substitutions of the amine present at the C2 position of the quinazoline core. Molecular docking studies in the active binding site also provided theoretical support for the experimental biological data acquired. The current study identifies a novel class of Aurora kinase inhibitors, which can further be used for the treatment of cancer.

  9. Phosphorylation of multifunctional nucleolar protein nucleophosmin (NPM1) by aurora kinase B is critical for mitotic progression.

    Science.gov (United States)

    Shandilya, Jayasha; Senapati, Parijat; Dhanasekaran, Karthigeyan; Bangalore, Suma S; Kumar, Manoj; Kishore, A Hari; Bhat, Akshay; Kodaganur, Gopinath S; Kundu, Tapas K

    2014-06-27

    The functional association of NPM1 with Aurora kinases is well documented. Surprisingly, although NPM1 is a well characterized phosphoprotein, it is unknown whether it is a substrate of Aurora kinases. We have found that Aurora kinases A and B can phosphorylate NPM1 at a single serine residue, Ser125, in vitro and in vivo. Phosphorylated-S125-NPM1 (pS125-NPM1) localizes to the midbody region during late cytokinesis where it colocalizes with Aurora B. The overexpression of mutant (S125A) NPM1 resulted in the deregulation of centrosome duplication and mitotic defects possibly due to cytokinesis failure. These data suggest that Aurora kinase B-mediated phosphorylation of NPM1 plays a critical role during mitosis, which could have wider implications in oncogenesis.

  10. Identification, SAR studies, and X-ray co-crystallographic analysis of a novel furanopyrimidine aurora kinase A inhibitor.

    Science.gov (United States)

    Coumar, Mohane Selvaraj; Tsai, Ming-Tsung; Chu, Chang-Ying; Uang, Biing-Jiun; Lin, Wen-Hsing; Chang, Chun-Yu; Chang, Teng-Yuan; Leou, Jiun-Shyang; Teng, Chi-Huang; Wu, Jian-Sung; Fang, Ming-Yu; Chen, Chun-Hwa; Hsu, John T-A; Wu, Su-Ying; Chao, Yu-Sheng; Hsieh, Hsing-Pang

    2010-02-01

    Herein we reveal a simple method for the identification of novel Aurora kinase A inhibitors through substructure searching of an in-house compound library to select compounds for testing. A hydrazone fragment conferring Aurora kinase activity and heterocyclic rings most frequently reported in kinase inhibitors were used as substructure queries to filter the in-house compound library collection prior to testing. Five new series of Aurora kinase inhibitors were identified through this strategy, with IC(50) values ranging from approximately 300 nM to approximately 15 microM, by testing only 133 compounds from a database of approximately 125,000 compounds. Structure-activity relationship studies and X-ray co-crystallographic analysis of the most potent compound, a furanopyrimidine derivative with an IC(50) value of 309 nM toward Aurora kinase A, were carried out. The knowledge gained through these studies could help in the future design of potent Aurora kinase inhibitors.

  11. Dispensability of the SAC Depends on the Time Window Required by Aurora B to Ensure Chromosome Biorientation

    Science.gov (United States)

    Monje-Casas, Fernando

    2015-01-01

    Aurora B and the spindle assembly checkpoint (SAC) collaborate to ensure the proper biorientation of chromosomes during mitosis. However, lack of Aurora B activity and inactivation of the SAC have a very different impact on chromosome segregation. This is most evident in Saccharomyces cerevisiae, since in this organism the lack of Aurora B is lethal and leads to severe aneuploidy problems, while the SAC is dispensable under normal growth conditions and mutants in this checkpoint do not show evident chromosome segregation defects. We demonstrate that the efficient repair of incorrect chromosome attachments by Aurora B during the initial stages of spindle assembly in budding yeast determines the lack of chromosome segregation defects in SAC mutants, and propose that the differential time window that Aurora B kinase requires to establish chromosome biorientation is the key factor that determines why some cells are more dependent on a functional SAC than others. PMID:26661752

  12. Discovery of a Previously Unrecognised Allusion to the Aurora Borealis in Paradise Lost, and Implications for Edmund Halley Scholarship

    Science.gov (United States)

    Cunningham, Clifford J.

    2014-11-01

    This research reveals that John Milton employed an allusion to the aurora borealis in the epic poem Paradise Lost which has not been recognised in more than three centuries of scholarly analysis. It further disproves the long-held belief, made popular by the astronomer Edmund Halley, that no notable aurora was visible in England in the seventeenth century. A study of the personal Latin diary of the Elizabethan historian William Camden shows that the famous aurora of 1621 was visible in England. While Pierre Gassendi has been credited with creation of the term 'aurora borealis' based on his report of the 1621 aurora, this study reaffirms a neglected analysis from 1986 that established the term originated with Galileo in 1619.

  13. Development of On-Line Direct Current Glow Discharge Source for Analysis of Isotope Ratio of Hydrogen

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>The present research is focused on the analysis of isotope ratio of the hydrogen by measuring an intensity ratio of hydrogen/deuterium/tritium fluxes. The direct current glow discharge tube may provide a

  14. Aurora-A controls cancer cell radio- and chemoresistance via ATM/Chk2-mediated DNA repair networks.

    Science.gov (United States)

    Sun, Huizhen; Wang, Yan; Wang, Ziliang; Meng, Jiao; Qi, Zihao; Yang, Gong

    2014-05-01

    High expression of Aurora kinase A (Aurora-A) has been found to confer cancer cell radio- and chemoresistance, however, the underlying mechanism is unclear. In this study, by using Aurora-A cDNA/shRNA or the specific inhibitor VX680, we show that Aurora-A upregulates cell proliferation, cell cycle progression, and anchorage-independent growth to enhance cell resistance to cisplatin and X-ray irradiation through dysregulation of DNA damage repair networks. Mechanistic studies showed that Aurora-A promoted the expression of ATM/Chk2, but suppressed the expression of BRCA1/2, ATR/Chk1, p53, pp53 (Ser15), H2AX, γH2AX (Ser319), and RAD51. Aurora-A inhibited the focus formation of γH2AX in response to ionizing irradiation. Treatment of cells overexpressing Aurora-A and ATM/Chk2 with the ATM specific inhibitor KU-55933 increased the cell sensitivity to cisplatin and irradiation through increasing the phosphorylation of p53 at Ser15 and inhibiting the expression of Chk2, γH2AX (Ser319), and RAD51. Further study revealed that BRCA1/2 counteracted the function of Aurora-A to suppress the expression of ATM/Chk2, but to activate the expression of ATR/Chk1, pp53, γH2AX, and RAD51, leading to the enhanced cell sensitivity to irradiation and cisplatin, which was also supported by the results from animal assays. Thus, our data provide strong evidences that Aurora-A and BRCA1/2 inversely control the sensitivity of cancer cells to radio- and chemotherapy through the ATM/Chk2-mediated DNA repair networks, indicating that the DNA repair molecules including ATM/Chk2 may be considered for the targeted therapy against cancers with overexpression of Aurora-A.

  15. Aurora kinase A controls meiosis I progression in mouse oocytes.

    Science.gov (United States)

    Saskova, Adela; Solc, Petr; Baran, Vladimir; Kubelka, Michal; Schultz, Richard M; Motlik, Jan

    2008-08-01

    Aurora kinase A (AURKA), which is a centrosome-localized serine/threonine kinase crucial for cell cycle control, is critically involved in centrosome maturation and spindle assembly in somatic cells. Active T288 phosphorylated AURKA localizes to the centrosome in the late G(2) and also spreads to the minus ends of mitotic spindle microtubules. AURKA activates centrosomal CDC25B and recruits cyclin B1 to centrosomes. We report here functions for AURKA in meiotic maturation of mouse oocytes, which is a model system to study the G(2) to M transition. Whereas AURKA is present throughout the entire GV-stage oocyte with a clear accumulation on microtubule organizing centers (MTOC), active AURKA becomes entirely localized to MTOCs shortly before germinal vesicle breakdown. In contrast to somatic cells in which active AURKA is present at the centrosomes and minus ends of microtubules, active AURKA is mainly located on MTOCs at metaphase I (MI) in oocytes. Inhibitor studies using Roscovitine (CDK1 inhibitor), LY-294002 (PI3K inhibitor) and SH-6 (PKB inhibitor) reveal that activation of AURKA localized on MTOCs is independent on PI3K-PKB and CDK1 signaling pathways and MOTC amplification is observed in roscovitine- and SH-6-treated oocytes that fail to undergo nuclear envelope breakdown. Moreover, microinjection of Aurka mRNA into GV-stage oocytes cultured in 3-isobutyl-1-methyl xanthine (IBMX)-containing medium to prevent maturation also results in MOTC amplification in the absence of CDK1 activation. Overexpression of AURKA also leads to formation of an abnormal MI spindle, whereas RNAi-mediated reduction of AURKA interferes with resumption of meiosis and spindle assembly. Results of these experiments indicate that AURKA is a critical MTOC-associated component involved in resumption of meiosis, MTOC multiplication, proper spindle formation and the metaphase I-metaphase II transition.

  16. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    OpenAIRE

    Pai, David,; Lacoste, Deanna,; Laux, C.

    2010-01-01

    International audience; In atmospheric pressure air preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determine...

  17. Glow curves and the emission of flux-grown BaFCl:Na crystals. [X radiation and gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Somaiah, K.; Hari Babu, V. (Osmania Univ., Hyderabad (India). Dept. of Physics)

    1984-08-01

    The thermoluminescence glow curves and the emission spectra of flux-grown BaFCl:Na crystals were recorded. An additional TL peak at 320 K, an optical absorption band at 570nm and an emission peak at 490 nm have been seen in X/..gamma..-irradiated crystals. Bleaching, room-temperature annealing and high-temperature emission results led us to conclude that the sodium impurity is responsible for the additional glow peak optical absorption band and emission peak.

  18. An Electron Sensor for the Pulsating Aurora 2 (Pulsaur 2) Mission

    Science.gov (United States)

    Scherrer, J. R.; Sharber, J. R.; Frahm, R. A.; Piepgrass, B.

    1996-01-01

    The purpose of this grant was to provide a low-energy electron detector to be flown on the PULSAUR 2 rocket payload for investigation of the pulsating aurora. In the course of this grant, the instrument, a tophat analyzer, was built and calibrated by the combined efforts of Southwest Research Institute, Mullard Space Sciences Laboratory, Rutherford Appleton Laboratory, and Goddard Space Flight Center, and successfully flown into an active, early morning, pulsating aurora over Andoya, Norway, on February 9, 1994. This report provides a description of the instrument and its calibration and gives examples of data obtained on the flight.

  19. Transient internally driven aurora at Jupiter discovered by Hisaki and the Hubble Space Telescope

    Science.gov (United States)

    Kimura, T.; Badman, S. V.; Tao, C.; Yoshioka, K.; Murakami, G.; Yamazaki, A.; Tsuchiya, F.; Bonfond, B.; Steffl, A. J.; Masters, A.; Kasahara, S.; Hasegawa, H.; Yoshikawa, I.; Fujimoto, M.; Clarke, J. T.

    2015-03-01

    Jupiter's auroral emissions reveal energy transport and dissipation through the planet's giant magnetosphere. While the main auroral emission is internally driven by planetary rotation in the steady state, transient brightenings are generally thought to be triggered by compression by the external solar wind. Here we present evidence provided by the new Hisaki spacecraft and the Hubble Space Telescope that shows that such brightening of Jupiter's aurora can in fact be internally driven. The brightening has an excess power up to ~550 GW. Intense emission appears from the polar cap region down to latitudes around Io's footprint aurora, suggesting a rapid energy input into the polar region by the internal plasma circulation process.

  20. Double Glow Plasma Hydrogen-free Carburizing on Commercial Purity Titanium

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gaohui; PAN Junde; HE Zhiyong; ZHANG Pingze; GAO Yuan; XU Zhong

    2005-01-01

    A carburized layer with special physical and chemical properties was formed on the surface of commercial purity titanium by a double glow plasma hydrogen-free carburizing technique. High-purity netlike solid graphite was used as a raw material and commercial purity titanium was used as the substrate material. Argon gas was used as the working gas. The carburized layer can be obviously observed under a microscope. X-ray diffraction indicates that TiC phase with higher hardness and dissociate state carbon phase was formed in the carburized layer. The glow discharge spectrum (GDS) analysis shows that the carbon concentration distributes gradiently along the depth of carburized layer. The surface hardness of the substrate increases obviously. The hardness distributes gradiently from the surface to inner of carburized layer. The friction coefficient reduces by more than 1/2, the ratio wear rate decreases by above three orders of magnitude. The wear resistance of the substrate material is improved consumedly.

  1. Evidence for large-area superemission into a high-current glow discharge

    Science.gov (United States)

    Hartmann, W.; Dominic, V.; Kirkman, G. F.; Gundersen, M. A.

    1988-10-01

    This letter presents evidence for large-area (≊1 cm2) cathode superemission (˜10 000 A/cm2) into a high-current glow discharge in a pseudospark or back lighted thyratron switch. Cathodes studied with a scannning electron microscope following operation at 6-8 kA, ≊1 μs pulse length, and 105 pulses in a low-pressure H2 discharge show evidence of melting of a thin surface layer within a radius of ˜4 mm, indicating that the discharge is a superdense glow with a cross-sectional area of the order of 1 cm2, rather than an arc. Further supporting evidence is provided by streak camera data. An ion beam present during the avalanche phase of the discharge is responsible for heating the cathode surface resulting in a significant field-enhanced thermionic emission.

  2. Optimal length of capacitive-discharge and glow-discharge excilamps

    Science.gov (United States)

    Boichenko, A. M.; Erofeev, M. V.; Sosnin, E. A.; Tarasenko, V. F.; Yakovlenko, S. I.

    2007-06-01

    The optimal tube length of capacitive-discharge and glow-discharge excimer lamps with ring and circular electrodes of equal radii is considered. It is demonstrated that, at the same potential difference between electrodes and their radii, the ratio of the optimal lengths of the tubes with circular and ring electrodes depends on width L of the ring electrodes. The ratio of the lengths decreases with decreasing L. A relationship between the tube length and radius, the width of ring electrodes, and the minimum voltage at the tube that provide for an approximately uniform glow of the discharge column in the presence of voltage pulses with opposite polarities at the electrodes is derived.

  3. Canard-induced mixed mode oscillations in an excitable glow discharge plasmas

    CERN Document Server

    Nurujjaman, M

    2014-01-01

    We demonstrated experimentally canard induced mixed mode oscillations (MMO) in an excitable glow discharge plasma, and the results are validated through numerical solution of the FitzHugh Nagumo (FHN) model. When glow discharge plasma is perturbed by applying a magnetic field, it shows mixed mode oscillatory activity, i.e., quasiperiodic small oscillations interposed with large bounded limit cycles oscillations. The initial quasiperiodic oscillations were observed to change into large amplitude limit cycle oscillations with magnetic field, and the number of these oscillation increases with increase in the magnetic field. Fourier analysis of both numerical and experimental results show that the origin of these oscillations are canard-induced phenomena, which occurs near the threshold of the control parameter. Further, the phase space plots also confirm that the oscillations are basically canard-induced MMOs.

  4. Chaotic-to-ordered state transition of cathode-sheath instabilities in DC glow discharge plasmas

    Indian Academy of Sciences (India)

    Md Nurujjaman; A N Sekar Iyengar

    2006-08-01

    Transition from chaotic to ordered state has been observed during the initial stage of a discharge in a cylindrical DC glow discharge plasma. Initially it shows a chaotic behavior but increasing the discharge voltage changes the characteristics of the discharge glow and shows a period subtraction of order 7 period → 5 period → 3 period → 1 period, i.e. the system goes to single mode through odd cycle subtraction. On further increasing the discharge voltage, the system goes through period doubling, like 1 period → 2 period → 4 period. On further increasing the voltage, the system goes to stable state through two period subtraction, like 4 period → 2 period → stable.

  5. Uniqueness theorem for the non-local ionization source in glow discharge and hollow cathode

    CERN Document Server

    Gorin, Vladimir V

    2012-01-01

    The paper is devoted to the proof of the uniqueness theorem for solution of the equation for the non-local ionization source in a glow discharge and a hollow cathode in general 3D geometry. The theorem is applied to wide class of electric field configurations, and to the walls of discharge volume, which have a property of incomplete absorption of the electrons. Cathode is regarded as interior singular source, which is placed arbitrarily close to the wall. The existence of solution is considered also. During the proof of the theorem many of useful structure formulae are obtained. Elements of the proof structure, which have arisen, are found to have physical sense. It makes clear physical construction of non-local electron avalanche, which builds a source of ionization in glow discharge at low pressures. Last has decisive significance to understand the hollow cathode discharge configuration and the hollow cathode effect.

  6. Plasma Treatment of Polyethylene Powder Particles in Hollow Cathode Glow Discharge

    Science.gov (United States)

    Wolter, Matthias; Quitzau, Meike; Bornholdt, Sven; Kersten, Holger

    2008-09-01

    Polyethylen (PE) is widely used in the production of foils, insulators, packaging materials, plastic bottles etc. Untreated PE is hydrophobic due to its unpolar surface. Therefore, it is hard to print or glue PE and the surface has to be modified before converting. In the present experiments a hollow cathode glow discharge is used as plasma source which is mounted in a spiral conveyor in order to ensure a combines transport of PE powder particles. With this set-up a homogeneous surface treatment of the powder is possible while passing the glow discharge. The plasma treatment causes a remarkable enhancement of the hydrophilicity of the PE powder which can be verified by contact angle measurements and X-ray photoelectron spectroscopy.

  7. Characteristics of a Normal Glow Discharge Excited by DC Voltage in Atmospheric Pressure Air

    Science.gov (United States)

    Li, Xuechen; Zhao, Huanhuan; Jia, Pengying

    2013-11-01

    Atmospheric pressure glow discharges were generated in an air gap between a needle cathode and a water anode. Through changing the ballast resistor and gas gap width between the electrodes, it has been found that the discharges are in normal glow regime judged from the current-voltage characteristics and visualization of the discharges. Results indicate that the diameter of the positive column increases with increasing discharge current or increasing gap width. Optical emission spectroscopy is used to calculate the electron temperature and vibrational temperature. Both the electron temperature and the vibrational temperature increases with increasing discharge current or increasing gap width. Spatially resolved measurements show that the maxima of electron temperature and vibrational temperature appeared in the vicinity of the needle cathode.

  8. Isotope effects on desorption kinetics of hydrogen isotopes implanted into stainless steel by glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Matsuyama, M.; Kondo, M.; Noda, N. [Hydrogen Isotope Research Center, University of Toyama, Gofuku, Toyama (Japan); Tanaka, M.; Nishimura, K. [National Institute for Fusion Science, Toki-shi, Gifu (Japan)

    2015-03-15

    In a fusion device the control of fuel particles implies to know the desorption rate of hydrogen isotopes by the plasma-facing materials. In this paper desorption kinetics of hydrogen isotopes implanted into type 316L stainless steel by glow discharge have been studied by experiment and numerical calculation. The temperature of a maximum desorption rate depends on glow discharge time and heating rate. Desorption spectra observed under various experimental conditions have been successfully reproduced by numerical simulations that are based on a diffusion-limited process. It is suggested, therefore, that desorption rate of a hydrogen isotope implanted into the stainless steel is limited by a diffusion process of hydrogen isotope atoms in bulk. Furthermore, small isotope effects were observed for the diffusion process of hydrogen isotope atoms. (authors)

  9. Hardness and stress of amorphous carbon film deposited by glow discharge and ion beam assisting deposition

    CERN Document Server

    Marques, F C

    2000-01-01

    The hardness and stress of amorphous carbon films prepared by glow discharge and by ion beam assisting deposition are investigated. Relatively hard and almost stress free amorphous carbon films were deposited by the glow discharge technique. On the other hand, by using the ion beam assisting deposition, hard films were also obtained with a stress of the same order of those found in tetrahedral amorphous carbon films. A structural analysis indicates that all films are composed of a sp sup 2 -rich network. These results contradict the currently accepted concept that both stress and hardness are only related to the concentration of sp sup 3 sites. Furthermore, the same results also indicate that the sp sup 2 sites may also contribute to the hardness of the films.

  10. Fading prediction in thermoluminescent materials using computerised glow curve deconvolution (CGCD)

    CERN Document Server

    Furetta, C; Weng, P S

    1999-01-01

    The fading of three different thermoluminescent (TL) materials, CaF sub 2 : Tm (TLD-300), manocrystalline LiF : Mg,Ti (DTG-4) and MgB sub 4 O sub 7 : Dy,Na has been studied at room temperature and at 50 deg. C of storage. The evolution as a function of the elapsed time of the whole glow curve as well as of the individual peaks has been analysed using the Computerised Glow Curve Deconvolution (CGCD) program developed at the NTHU. The analysis allows to predict the loss of the dosimetric information and to make any correction is necessary for using the TL dosimeters in practical applications. Furthermore, it is well demonstrated that using CGCD it is not necessary to anneal the peaks having a rapid fading to avoid, then, any interfering effect on the more stable peaks.

  11. SkyGlowNet: Multi-Disciplinary Independent Student Research in Environmental Light at Night Monitoring

    Science.gov (United States)

    Craine, B. L.; Craine, E. R.; Culver, R. B.; DeBenedetti, J. C.; Flurchick, K. M.

    2014-07-01

    SkyGlowNet uses Internet-enabled sky brightness meters (iSBM) to monitor sky brightness over school sites. The data are used professionally and in STEM outreach to study natural and artificial sources of sky brightness, light pollution, energy efficiency, and environmental and health impacts of artificial night lighting. The iSBM units are owned by participating institutions and managed by faculty or students via proprietary Internet links. Student data are embargoed for two semesters to allow students to analyze data and publish results, then they are moved to a common area where students from different institutions can collaborate. The iSBM units can be set to operate automatically each night. Their data include time, sky brightness, weather conditions, and other related parameters. The data stream can be viewed and processed online or downloaded for study. SkyGlowNet is a unique, multi-disciplinary, real science program aiding research for science and non-science students.

  12. Analysis Of The Different Zones Of Glow Discharge Of Ethyl Alcohol (C2H6O)

    Science.gov (United States)

    Torres, C.; Reyes, P. G.; Mulia, J.; Castillo, F.; Martínez, H.

    2014-05-01

    The aim of this work is to explore the emission spectroscopy of ethyl alcohol in some regions, also is determine the result elements of the glow discharge, the spectrums were observed in a range of 200 at 1100 nm in the different zones inside of the tube at different distances of 20 and 30 cm. The elements are: in anode region C6H5 (483.02nm), CHO (519.56nm) and H2 (560.47nm), in the positive column CO2+ (315.52 y 337.00nm), O+ (357.48nm), CH+ (380.61nm) and CO+ (399.73nm); in the cathode region we observed O+ (391.19nm), CHOCHO (428.00nm), CO+ (471.12nm) and H2 (656.52nm). C6H5, CHO y H2 species occurring in all regions analyzed varying the glow discharge emission intensity.

  13. The glow duration time influence on the ionization rate detected in the diodes filled with noble gases on mbar pressures

    Directory of Open Access Journals (Sweden)

    Stepanović Olivera M.

    2003-01-01

    Full Text Available The results of the glow current duration time (glowing-time influence on the ionization rate detected in the gas filled diodes are presented. The electrical breakdown was detected as the minimal current impulse. After that diode glow from the minimal glowing-time (10-3 s, up to the maximal 103 s which overlap the time of the stationary regime formation in the gas diode tube. The diodes were with volumes of 300 cm3, but with a diode gap volume of about 1 cm3 and filled with helium, neon, argon or krypton, at the pressures of the order of mbar. The ionization rates were detected as the residual ionization after the glowing was interrupted, using the electrical breakdown time delay measuring method. The influence of the gap distance stationary current values and the relaxation period were also investigated. The result shows that the stationary regime in such a gas diode is established after the glowing time of 1-3 s, although the breakdown formative times were smaller then 1 ms.

  14. Transitions between corona, glow, and spark regimes of nanosecond repetitively pulsed discharges in air at atmospheric pressure

    Science.gov (United States)

    Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.

    2010-05-01

    In atmospheric pressure air preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge regime. In particular, the experimental conditions necessary for the glow regime of NRP discharges have been determined, with the notable result that there exists a minimum and maximum gap distance for its existence at a given ambient gas temperature. The minimum gap distance increases with decreasing gas temperature, whereas the maximum does not vary appreciably. To explain the experimental results, an analytical model is developed to explain the corona-to-glow (C-G) and glow-to-spark (G-S) transitions. The C-G transition is analyzed in terms of the avalanche-to-streamer transition and the breakdown field during the conduction phase following the establishment of a conducting channel across the discharge gap. The G-S transition is determined by the thermal ionization instability, and we show analytically that this transition occurs at a certain reduced electric field for the NRP discharges studied here. This model shows that the electrode geometry plays an important role in the existence of the NRP glow regime at a given gas temperature. We derive a criterion for the existence of the NRP glow regime as a function of the ambient gas temperature, pulse repetition frequency, electrode radius of curvature, and interelectrode gap distance.

  15. Effect of Atmospheric Pressure Glow Discharge Treatment on Polymerization of Acrylic Fabric and Its Printing Behavior

    Directory of Open Access Journals (Sweden)

    D M El-Zeer

    2014-03-01

    Full Text Available Acrylic fibers have been treated by atmospheric pressure glow discharge (APGD plasma in open air to enhance surface antistatic properties. The treated surfaces are investigated by scanning electron microscopy (SEM, Fourier-Transition Infrared Spectroscopy (FTIR and Atomic Force Microscope (AFM. Plasma treatment of acrylic fabric has been found to increase the surface roughness, modify the nature and density of surface functionalities, and drastically improve the wettability and antistatic ability of acrylic fibers.

  16. A Monte Carlo Simulation for the Ion Transport in Glow Discharges with Dusts

    Institute of Scientific and Technical Information of China (English)

    SUN Ai-Ping; PU Wei; QIU Xiao-Ming

    2001-01-01

    We use the Monte Carlo method to simulate theion transport in the rf parallel plate glow discharge with a negative-voltage pulse connected to the electrode. It is found that self-consistent field, dust charge, dust concentration,and dust size influence the energy distribution and the density of the ions arriving at the target, and in particular, the latter two make significant influence. As dust concentration or dust size increases, the number of ions arriving at the target reduces greatly.

  17. Aligned Carbon Nanotubes Array by DC Glow Plasma Etching for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Yongfeng Luo

    2013-01-01

    Full Text Available To open the end of carbon nanotubes and make these ends connect with functional carboxyl group, aligned carbon nanotubes (CNTs arrays was etched by DC glow oxygen-argon plasma. With these open-ended carbon nanotubes array as electrode materials to build supercapacitor, we found that the capacity (32.2 F/g increased significantly than that of pure carbon nanotubes (6.7 F/g.

  18. Numerical simulation of a direct current glow discharge in atmospheric pressure helium

    Science.gov (United States)

    Yin, Zeng-Qian; Wang, Yan; Zhang, Pan-Pan; Zhang, Qi; Li, Xue-Chen

    2016-12-01

    Characteristics of a direct current (DC) discharge in atmospheric pressure helium are numerically investigated based on a one-dimensional fluid model. The results indicate that the discharge does not reach its steady state till it takes a period of time. Moreover, the required time increases and the current density of the steady state decreases with increasing the gap width. Through analyzing the spatial distributions of the electron density, the ion density and the electric field at different discharge moments, it is found that the DC discharge starts with a Townsend regime, then transits to a glow regime. In addition, the discharge operates in a normal glow mode or an abnormal glow one under different parameters, such as the gap width, the ballast resistors, and the secondary electron emission coefficients, judged by its voltage-current characteristics. Project supported by the National Natural Science Foundation of China (Grant Nos. 11575050 and 10805013), the Midwest Universities Comprehensive Strength Promotion Project, the Natural Science Foundation of Hebei Province, China (Grant Nos. A2016201042 and A2015201092), and the Research Foundation of Education Bureau of Hebei Province, China (Grant No. LJRC011).

  19. Generation of uniform atmospheric pressure argon glow plasma by dielectric barrier discharge

    Indian Academy of Sciences (India)

    Raju Bhai Tyata; Deepak Prasad Subedi; Rajendra Shrestha; Chiow San Wong

    2013-03-01

    In this paper, atmospheric pressure glow discharges (APGD) in argon generated in parallel plate dielectric barrier discharge system is investigated by means of electrical and optical measurements. Using a high voltage (0–20 kV) power supply operating at 10–30 kHz, homogeneous and steady APGD has been observed between the electrodes with gap spacing from 0.5 mm to 2 mm and with a dielectric barrier of thickness 2 mm while argon gas is fed at a controlled flow rate of 11/min. The electron temperature and electron density of the plasma are determined by means of optical emission spectroscopy. Our results show that the electron density of the discharge obtained is of the order of 1016 cm-3 while the electron temperature is estimated to be 0.65 eV. The important result is that electron density determined from the line intensity ratio method and stark broadening method are in very good agreement. The Lissajous figure is used to estimate the energy deposited to the glow discharge. It is found that the energy deposited to the discharge is in the range of 20 to 25 $\\$J with a discharge voltage of 1.85 kV. The energy deposited to the discharge is observed to be higher at smaller gas spacing. The glow discharge plasma is tested to be effective in reducing the hydrophobicity of polyethylene film significantly.

  20. Micro glow plasma for localized nanostructural modification of carbon nanotube forest

    Science.gov (United States)

    Sarwar, Mirza Saquib us; Xiao, Zhiming; Saleh, Tanveer; Nojeh, Alireza; Takahata, Kenichi

    2016-08-01

    This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ˜30% and ˜300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.

  1. Ignition and dynamics of high-voltage glow discharge plasma implantation

    Science.gov (United States)

    Fu, Ricky K. Y.; Chu, Paul K.; Tian, X. B.; Yang, S. Q.

    2006-01-01

    The self-ignition and dynamics of glow discharge plasma in the pulsed high-voltage plasma immersion ion implantation mode have been investigated. After ignition during the pulse-on period, the glow discharge continues to be sustained for a long period of time after the high-voltage pulse has been turned off as monitored by a Langmuir probe. The glow discharge and ignition lie on the left side of the Paschen curve when pd (gas pressure times electrode separation) is adjusted by using different anode to cathode distances utilizing a conducting grounded grid. The increased or constant implantation current Ia reveals that the ion sheath is stable and conforms to the cathode structure as the plasma density increases by one to two orders of magnitude towards the anode. In addition, the duration of the post-pulse-off plasma can be as long as several times of the pulse duration. The ignition time and duration of the plasma depend on the working pressure, applied voltage and pulse duration.

  2. Quantification Approach of Gas Temperate Distribution in Atmospheric Positive DC Glow Discharge Measured by Spectroscopic Imaging

    Science.gov (United States)

    Sasamoto, Ryo; Orii, Hideaki; Matsumoto, Takao; Izawa, Yasuji; Nishijima, Kiyoto

    2015-09-01

    In our previous work, a two-dimensional (2D) gas temperature distribution in a positive DC steady-state glow corona was qualitatively measured by spectroscopic imaging. Spectral images of its glow corona were taken using ICCD camera with ultra-narrow band-pass filters, and they were corresponded to the head and tail of a second positive system bands of nitrogen (2PS N2 (0-2)). The qualitative gas temperature was obtained from the emission intensity ratio (I2 Ptail/I2 Phead) between the head and tail of 2PS N2 (0-2). This emission intensity ratio also equals the rotational temperature (TR) , and TR almost equals the gas temperature (TG) in atmospheric pressure. In this work, the qualitative 2D gas temperature distribution was derived from 2D I2 Ptail/I2 Phead plots, and the calibration date of I2 Ptail/I2 Phead for TR was accumulated by investigating the relationship between the spatially average absolute gas temperature (Tav) obtained by single-point spectroscopic measurement and the average value of I2 Ptail/I2 Phead plots. On the basis of the calibration date, a spectroscopically-imaged qualitative 2D I2 Ptail/I2 Phead distribution in a positive DC glow corona was converted to a quantitative 2D image of gas rotational temperature.

  3. FT Tokamak Upgrade (FTU) vacuum vessel section cleaning by glow discharge in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ciotti, M.; Apicella, M.L.; Verdini, L.; Ferro, C.

    1991-09-01

    The possibility of applying glow discharge in hydrogen for the cleaning of the FTU (Frascati Tokamak Upgrade) vacuum chamber was analyzed on a 1:1 scale toroidal section by using the same operating conditions as foreseen for the machine. The discharge was maintained for six hours in the chamber with the wall temperature kept at 150 degrees C. The partial pressures at the end of the cleaning run were compared with those obtained by using only thermal outgassing at the same temperature. A reduction of about a factor of two in the H/sub 2/0 and C0/sub 2/ partial pressures was observed, related to a better cleanness of the surface. It was found that the high temperature during the glow discharge cleaning not only increases the efficiency of the discharge, but it is an efficient tool to remove impurities from the hidden regions, defined by the thermal shields that cover all the vacuum vessel walls not directly exposed to the glow discharge.

  4. Development and synthesis of durable self-glowing crystals doped with plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Burakov, B.E. [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 2nd Site, 1, Rentgena Street, St. Petersburg 197101 (Russian Federation); Domracheva, Ya.V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya Street, St. Petersburg 194021 (Russian Federation)], E-mail: y.domracheva@mail.ioffe.ru; Zamoryanskaya, M.V. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 26, Polytekhnicheskaya Street, St. Petersburg 194021 (Russian Federation); Petrova, M.A.; Garbuzov, V.M.; Kitsay, A.A.; Zirlin, V.A. [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, 2nd Site, 1, Rentgena Street, St. Petersburg 197101 (Russian Federation)

    2009-03-15

    Different crystalline materials doped with plutonium and other alpha-emitting radionuclides are characterized by self-glowing. Some of these materials, in particular, monocrystalline ones, which are highly chemically resistant, mechanically durable, and stable under radiation damage are promising for application in optical couplers, robotics and medicine. They might be used for a long time (from tens to hundreds years) in aggressive chemical media and space. Crystals with low content of radionuclides (less than 0.1 wt%) but intensive self-glowing are main subject of interest. Phosphate and silicate single crystals with zircon structure: xenotime, (Y,...)PO{sub 4} and zircon, (Zr,...)SiO{sub 4}, were doped with {sup 238}Pu, {sup 237}Np and non-radioactive elements: Eu{sup 3+}; In{sup 3+} and Tb{sup 3+}. The most intensive self-glowing was obtained for xenotime crystals doped with 0.1 wt% {sup 238}Pu and Eu; and for zircon crystals doped with 0.01 wt% {sup 238}Pu and coupled admixture of In and Tb.

  5. Two-dimensional, hybrid model of glow discharge in hollow cathode geometries

    Energy Technology Data Exchange (ETDEWEB)

    Fiala, A.; Pitchford, L.C.; Boeuf, J.P. [Universite Paul Sabatier, Toulouse (France)

    1995-12-31

    Low pressure glow discharges in plane-plane geometries have been studied extensively over the years and most of their features are known from experiments and numerical simulation. If a plane cathode is replaced by a cathode with some hollow structure, then, for a certain range of conditions, the negative glows of opposite (adjacent) cathode walls overlap and the discharge behaviour dramatically changes. The voltage is lower at a constant current and the current is even several orders of magnitude higher for a given voltage than for the plane cathode. At the same time, the intensity of the light emission from the discharge considerably increases. This effect is called the hollow cathode effect. There are several physical phenomena which could be responsible for the big efficiency of the hollow cathode discharges. The recent investigations based on the Monte Carlo simulation of the electron kinetics have shown that the trapping of energetic electrons in the hollow cathode cavity can explain the order of magnitude of the hollow cathode effect. The configuration of the discharge tube presented in fig. 1 is used here to study the behaviour of glow discharges in a hollow cathode means of numerical simulation.

  6. Methane Conversion to C2 Hydrocarbons by Abnormal Glow Discharge at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    Dai Wei; Yu Hui; Chen Qi; Yin Yongxiang; Dai Xiaoyan

    2005-01-01

    Methane conversion to C2 hydrocarbons has been investigated with the addition of hydrogen in a plasma reactor of abnormal glow discharge at atmospheric pressure. The aim of this experiment is to minimize coke formation and improve discharge stability. The typical conditions in the experiment are 300 ml of total feed flux and 400 W of discharge power. The experimental results show that methane conversion is from 91.6% to 35.2% in mol, acetylene selectivity is from 90.2% to 57.6%, and ethylene selectivity is approximately from 7.8% to 3.6%,where the coke increases gradually along with the increase of CH4/H2 from 2: 8 to 9: 1. A stable discharge for a considerable running time can be obtained only at a lower ratio of CH4/H2= 2:8 or 3: 7. These phenomena indicate that the coke deposition during methane conversion is obviously reduced by adding a large amount of hydrogen during an abnormal glow discharge.A qualitative interpretation is presented, namely, with abundant hydrogen, the possibility that hydrogen molecules are activated to hydrogen radicals is increased with the help of the abnormal glow discharge. These hydrogen radicals react with carbon radicals to form C2 hydrocarbon products. Therefore, the deposition of coke is restrained.

  7. Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air

    Science.gov (United States)

    Reece Roth, J.

    2004-11-01

    The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering

  8. Preliminary Results from a Coordinated Hisaki/Chandra/XMM-Newton Study of the Jovian Aurora and Io Plasma Torus

    Science.gov (United States)

    Kraft, Ralph; Kimura, Tomoki; Elsner, Ronald; Branduardi-Raymont, Graziella; Gladstone, Randy; Badman, Sarah Victoria; Ezoe, Yuichiro; Murakami, Go; Murray, Stephen S.; Roediger, Elke; Tsuchiya, Fuminori; Yamazaki, Atsushi; Yoshikawa, Ichiro; Yoshioka, Kazuo

    2014-01-01

    We present preliminary results from a coordinated Hisaki/Chandra/XMM-Newton observational campaign of the Jovian aurora and Io plasma torus. The data were taken over a three week period in April, 2014. Jupiter was observed continuously with Hisaki, six times with the Chandra/HRC instrument for roughly 12 hours per observation, and twice by XMM-Newton. The goal of this observational campaign was to understand how energy and matter are exchanged between the Jovian aurora, the IPT, and the Solar wind. X-ray observations provide key diagnostics on highly stripped ions and keV electrons in the Jovian magnetosphere. We use the temporal, spatial, and spectral capabilities of the three instruments to search for correlated variability between the Solar wind, the EUV-emitting plasma of the IPT and UV aurora, and the ions responsible for the X-ray aurora. Preliminary analysis suggests a strong 45 min periodicity in the EUV emission from the electron aurora. There is some evidence for complex variability of the X-ray auroras on scales of tens of minutes. There is also clear morphological changes in the X-ray aurora that do not appear to be correlated with either variations in the IPT or Solar wind.

  9. Inter-domain Cooperation in INCENP Promotes Aurora B Relocation from Centromeres to Microtubules

    NARCIS (Netherlands)

    van der Horst, Armando; Vromans, Martijn J M; Bouwman, Kim; van der Waal, Maike S; Hadders, Michael A; Lens, Susanne M A; Lens, SMA

    2015-01-01

    The chromosomal passenger complex is essential for error-free chromosome segregation and proper execution of cytokinesis. To coordinate nuclear division with cytoplasmic division, its enzymatic subunit, Aurora B, relocalizes from centromeres in metaphase to the spindle midzone in anaphase. In buddin

  10. 76 FR 65216 - Beacon Medical Services, LLC, Aurora, CO; Notice of Negative Determination Regarding Application...

    Science.gov (United States)

    2011-10-20

    ... (76 FR 40401). The workers of Beacon Medical Services are engaged in activities related ] to the... Employment and Training Administration Beacon Medical Services, LLC, Aurora, CO; Notice of Negative... apply for Trade Adjustment Assistance (TAA) applicable to workers and former workers of Beacon...

  11. Discovery of Salamandra atra aurorae (Trevisan, 1982 on the Altopiano di Vezzena, Trentino (Northeastern Italy

    Directory of Open Access Journals (Sweden)

    Wouter Beukema

    2008-05-01

    Full Text Available Aurora’s Alpine Salamander is a limited distributed subspecies endemic to the Altopiano di Asiago, Veneto. In the current paper the occurrence of Salamandra atra aurorae is described for the Altopiano di Vezzena, Trentino. The aim of this paper is to review the distribution as well as to comment on the conservational status of the subspecies in Trentino.

  12. Ionospheric characteristics of the dusk-side branch of the two-cell aurora

    Directory of Open Access Journals (Sweden)

    J.-H. Shue

    2006-03-01

    Full Text Available The two-cell aurora is characterized by azimuthally elongated regions of enhanced auroral brightness over extended local times in the dawn and dusk sectors. Its association with the convection, particle precipitation, and field-aligned currents under various phases of substorms has not been fully understood. With Polar Ultraviolet Imager auroral images in conjunction with Defense Meteorological Satellite Program (DMSP F12 spacecraft on the dusk-side branch of the two-cell aurora, we are able to investigate an association of the auroral emissions with the electric fields, field-aligned currents, and energy flux of electrons. Results show that the substorm expansion onset does not significantly change the orientation of the dusk-side branch of the two-cell aurora. Also, the orientation of the magnetic deflection vector produced by the region 1 field-aligned current changed from 73±1° to the DMSP trajectory during the substorm growth phase, to 44±6° to the DMSP trajectory during the substorm expansion phase. With a comparison between the orientation of the dusk-side branch of the two-cell aurora and the orientation of the magnetic deflection vector, it is found that the angular difference between the two orientations is 28±5° during the substorm growth phase, and 13±6° during the substorm expansion phase.

  13. Tension sensing by Aurora B kinase is independent of survivin-based centromere localization.

    Science.gov (United States)

    Campbell, Christopher S; Desai, Arshad

    2013-05-01

    Accurate segregation of the replicated genome requires chromosome biorientation on the spindle. Biorientation is ensured by Aurora B kinase (Ipl1), a member of the four-subunit chromosomal passenger complex (CPC). Localization of the CPC to the inner centromere is central to the current model for how tension ensures chromosome biorientation: kinetochore-spindle attachments that are not under tension remain close to the inner centromere and are destabilized by Aurora B phosphorylation, whereas kinetochores under tension are pulled away from the influence of Aurora B, stabilizing their microtubule attachments. Here we show that an engineered truncation of the Sli15 (known as INCENP in humans) subunit of budding yeast CPC that eliminates association with the inner centromere nevertheless supports proper chromosome segregation during both mitosis and meiosis. Truncated Sli15 suppresses the deletion phenotypes of the inner-centromere-targeting proteins survivin (Bir1), borealin (Nbl1), Bub1 and Sgo1 (ref. 6). Unlike wild-type Sli15, truncated Sli15 localizes to pre-anaphase spindle microtubules. Premature targeting of full-length Sli15 to microtubules by preventing Cdk1 (also known as Cdc28) phosphorylation also suppresses the inviability of Bir1 deletion. These results suggest that activation of Aurora B kinase by clustering either on chromatin or on microtubules is sufficient for chromosome biorientation.

  14. Facile identification of dual FLT3-Aurora A inhibitors: a computer-guided drug design approach.

    Science.gov (United States)

    Chang Hsu, Yung; Ke, Yi-Yu; Shiao, Hui-Yi; Lee, Chieh-Chien; Lin, Wen-Hsing; Chen, Chun-Hwa; Yen, Kuei-Jung; Hsu, John T-A; Chang, Chungming; Hsieh, Hsing-Pang

    2014-05-01

    Computer-guided drug design is a powerful tool for drug discovery. Herein we disclose the use of this approach for the discovery of dual FMS-like receptor tyrosine kinase-3 (FLT3)-Aurora A inhibitors against cancer. An Aurora hit compound was selected as a starting point, from which 288 virtual molecules were screened. Subsequently, some of these were synthesized and evaluated for their capacity to inhibit FLT3 and Aurora kinase A. To further enhance FLT3 inhibition, structure-activity relationship studies of the lead compound were conducted through a simplification strategy and bioisosteric replacement, followed by the use of computer-guided drug design to prioritize molecules bearing a variety of different terminal groups in terms of favorable binding energy. Selected compounds were then synthesized, and their bioactivity was evaluated. Of these, one novel inhibitor was found to exhibit excellent inhibition of FLT3 and Aurora kinase A and exert a dramatic antiproliferative effect on MOLM-13 and MV4-11 cells, with an IC50 value of 7 nM. Accordingly, it is considered a highly promising candidate for further development.

  15. Polo-like kinase-1 controls Aurora A destruction by activating APC/C-Cdh1.

    Directory of Open Access Journals (Sweden)

    Renske van Leuken

    Full Text Available Polo-like kinase-1 (Plk1 is activated before mitosis by Aurora A and its cofactor Bora. In mitosis, Bora is degraded in a manner dependent on Plk1 kinase activity and the E3 ubiquitin ligase SCF-betaTrCP. Here, we show that Plk1 is also required for the timely destruction of its activator Aurora A in late anaphase. It has been shown that Aurora A destruction is controlled by the auxiliary subunit Cdh1 of the Anaphase-Promoting Complex/Cyclosome (APC/C. Remarkably, we found that Plk1-depletion prevented the efficient dephosphorylation of Cdh1 during mitotic exit. Plk1 mediated its effect on Cdh1, at least in part, through direct phosphorylation of the human phosphatase Cdc14A, controlling the phosphorylation state of Cdh1. We conclude that Plk1 facilitates efficient Aurora A degradation through APC/C-Cdh1 activation after mitosis, with a potential role for hCdc14A.

  16. Allosteric inhibition of Aurora-A kinase by a synthetic vNAR domain.

    Science.gov (United States)

    Burgess, Selena G; Oleksy, Arkadiusz; Cavazza, Tommaso; Richards, Mark W; Vernos, Isabelle; Matthews, David; Bayliss, Richard

    2016-07-01

    The vast majority of clinically approved protein kinase inhibitors target the ATP-binding pocket directly. Consequently, many inhibitors have broad selectivity profiles and most have significant off-target effects. Allosteric inhibitors are generally more selective, but are difficult to identify because allosteric binding sites are often unknown or poorly characterized. Aurora-A is activated through binding of TPX2 to an allosteric site on the kinase catalytic domain, and this knowledge could be exploited to generate an inhibitor. Here, we generated an allosteric inhibitor of Aurora-A kinase based on a synthetic, vNAR single domain scaffold, vNAR-D01. Biochemical studies and a crystal structure of the Aurora-A/vNAR-D01 complex show that the vNAR domain overlaps with the TPX2 binding site. In contrast with the binding of TPX2, which stabilizes an active conformation of the kinase, binding of the vNAR domain stabilizes an inactive conformation, in which the αC-helix is distorted, the canonical Lys-Glu salt bridge is broken and the regulatory (R-) spine is disrupted by an additional hydrophobic side chain from the activation loop. These studies illustrate how single domain antibodies can be used to characterize the regulatory mechanisms of kinases and provide a rational basis for structure-guided design of allosteric Aurora-A kinase inhibitors.

  17. Aurora B kinase controls the separation of centromeric and telomeric heterochromatin

    OpenAIRE

    Gachet, Yannick; Reyes, Celine; Tournier, Sylvie

    2015-01-01

    The segregation of chromosomes is coordinated at multiple levels to prevent chromosome loss, a phenotype frequently observed in cancers. We recently described an essential role for telomeres in the physical separation of chromosomes and identified Aurora B kinase as a double agent involved in the separation of centromeric and telomeric heterochromatin.

  18. Aurora B kinase controls the separation of centromeric and telomeric heterochromatin.

    Science.gov (United States)

    Gachet, Yannick; Reyes, Celine; Tournier, Sylvie

    2016-03-01

    The segregation of chromosomes is coordinated at multiple levels to prevent chromosome loss, a phenotype frequently observed in cancers. We recently described an essential role for telomeres in the physical separation of chromosomes and identified Aurora B kinase as a double agent involved in the separation of centromeric and telomeric heterochromatin.

  19. In vivo FRET imaging revealed a regulatory role of RanGTP in kinetochore-microtubule attachments via Aurora B kinase.

    Directory of Open Access Journals (Sweden)

    Yoke-Peng Lee

    Full Text Available Under the fluctuating circumstances provided by the innate dynamics of microtubules and opposing tensions resulted from microtubule-associated motors, it is vital to ensure stable kinetochore-microtubule attachments for accurate segregation. However, a comprehensive understanding of how this regulation is mechanistically achieved remains elusive. Using our newly designed live cell FRET time-lapse imaging, we found that post-metaphase RanGTP is crucial in the maintenance of stable kinetochore-microtubule attachments by regulating Aurora B kinase via the NES-bearing Mst1. More importantly, our study demonstrates that by ensuring stable alignment of metaphase chromosomes prior to segregation, RanGTP is indispensible in governing the genomic integrity and the fidelity of cell cycle progression. Our findings suggest an additional role of RanGTP beyond its known function in mitotic spindle assembly during the prometaphase-metaphase transition.

  20. Antiparallel magnetic merging signatures during IMF BY>>0: longitudinal and latitudinal cusp aurora bifurcations

    Directory of Open Access Journals (Sweden)

    S. Massetti

    2006-09-01

    Full Text Available A prominent dayside auroral event, occurred during an IMF BY-dominated time interval, and characterized by the contemporaneous longitudinal and latitudinal cusp bifurcations, is reported. The event was recorded the 19 December 2002, between about 09:30–10:45 UT, by the ITACA2 twin auroral monitors system, in the Greenland-Svalbard zone. The splitting of the ionospheric footprint of the geomagnetic cusp, traced by the dayside auroral activity, was recently identified with the signatures of antiparallel reconnection episodes ongoing at different magnetopause locations, during large IMF BY periods. The first part of the event showed a broad longitudinal bifurcation of the red-dominated cusp aurora, displaced in the prenoon and postnoon, with a separation up to ~1800 km, during northeast directed IMF (clock-angle rotating from 45° to 90°. This observation widens the range of IMF regimes that are known to drive a longitudinal bifurcation of the cusp, since previous case-studies reported these events to occur during southeast/southwest oriented IMF (clock-angle ≈135°. The second part of the event, developed when the IMF turned to a nearly horizontal orientation (BY>>0, BZ~0, clock-angle ~90°, and exhibited the simultaneous activation of the cusp auroras in three distinct areas: i two of them associated to the above-mentioned longitudinally bifurcated cusp (~73°–75° CGM latitude, type 1 cusp aurora, and linked to (nearantiparallel magnetic reconnection patches equatorward the northern and the southern cusp, ii the other one characterized by isolated high-latitude (~76°–77° CGM latitude, type 2 cusp aurora rayed arc(s with intense green emission, and triggered by (nearantiparallel merging at the northern lobe (usually observed during positive IMF BZ, poleward the local cusp. During this phase, the longitudinal separation of the low-latitude type~1 cusp aurora was about 1000 km wide, with a 500 km gap, while the latitudinal separation

  1. The first scientific description of aurora borealis: the 10 September 1580 event in Transylvania, recorded by Marcello Squarcialupi

    Science.gov (United States)

    Kázmér, Miklós; Timár, Gábor

    2016-12-01

    The first scientific treatise on aurora borealis was published by Marcello Squarcialupi, an Italian medical doctor working in the court of the Hungarian Prince of Transylvania. His book, De coelo ardore, described the aurora of 10 September 1580 in great detail, providing exact data from his personal observations on the time, direction, shape, colour, and variability. He invoked a rational explanation, bringing up only natural causes, and confronted these with the ruling Aristotelian view. The original Latin text describing the aurora is provided, with an English translation.

  2. Protein tyrosine phosphatase receptor delta acts as a neuroblastoma tumor suppressor by destabilizing the aurora kinase a oncogene

    Directory of Open Access Journals (Sweden)

    Meehan Maria

    2012-02-01

    Full Text Available Abstract Background Protein tyrosine phosphatase receptor delta (PTPRD is a member of a large family of protein tyrosine phosphatases which negatively regulate tyrosine phosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns of PTPRD, indicating a potential tumor suppressor function for this gene. The molecular mechanism, however, by which PTPRD renders a tumor suppressor effect in neuroblastoma is unknown. Results As a molecular mechanism, we demonstrate that PTPRD interacts with aurora kinase A (AURKA, an oncogenic protein that is over-expressed in multiple forms of cancer, including neuroblastoma. Ectopic up-regulation of PTPRD in neuroblastoma dephosphorylates tyrosine residues in AURKA resulting in a destabilization of this protein culminating in interfering with one of AURKA's primary functions in neuroblastoma, the stabilization of MYCN protein, the gene of which is amplified in approximately 25 to 30% of high risk neuroblastoma. Conclusions PTPRD has a tumor suppressor function in neuroblastoma through AURKA dephosphorylation and destabilization and a downstream destabilization of MYCN protein, representing a novel mechanism for the function of PTPRD in neuroblastoma.

  3. Protein tyrosine phosphatase receptor delta acts as a neuroblastoma tumor suppressor by destabilizing the aurora kinase a oncogene

    LENUS (Irish Health Repository)

    Meehan, Maria

    2012-02-05

    Abstract Background Protein tyrosine phosphatase receptor delta (PTPRD) is a member of a large family of protein tyrosine phosphatases which negatively regulate tyrosine phosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns of PTPRD, indicating a potential tumor suppressor function for this gene. The molecular mechanism, however, by which PTPRD renders a tumor suppressor effect in neuroblastoma is unknown. Results As a molecular mechanism, we demonstrate that PTPRD interacts with aurora kinase A (AURKA), an oncogenic protein that is over-expressed in multiple forms of cancer, including neuroblastoma. Ectopic up-regulation of PTPRD in neuroblastoma dephosphorylates tyrosine residues in AURKA resulting in a destabilization of this protein culminating in interfering with one of AURKA\\'s primary functions in neuroblastoma, the stabilization of MYCN protein, the gene of which is amplified in approximately 25 to 30% of high risk neuroblastoma. Conclusions PTPRD has a tumor suppressor function in neuroblastoma through AURKA dephosphorylation and destabilization and a downstream destabilization of MYCN protein, representing a novel mechanism for the function of PTPRD in neuroblastoma.

  4. Influence of plasma collective effects on the structure of the aurora borealis streamers

    Energy Technology Data Exchange (ETDEWEB)

    Dzyubenko, N.I.; Ivchenko, V.N.; Milinevskii, G.P.; Mishin, E.V.

    1980-06-05

    A two-maximum altitude structure was observed in the glow produced by a beam of high energy electrons entering the ionosphere; this structure agrees with theory which takes into account the effect of collisions on the dynamics of strong Langmuir turbulence excited by the beam.

  5. Characterization of W Coating on Cu Substrate Prepared by Double-Glow Discharge%Characterization of W Coating on Cu Substrate Prepared by Double-Glow Discharge

    Institute of Scientific and Technical Information of China (English)

    张福斌; 王正铎; 陈强; 蔡惠平

    2012-01-01

    In this study, tungsten (W) was coated on a copper (Cu) substrate by using doubleglow discharge technique using a pure W panel as the target and argon (Ar) as the discharge and sputtering gas. The crystal structure of the W coating was examined by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was performed with cross-section images to investigate the penetration depth of W into the Cu body. Additionally, the properties of wearability resistance, corrosion resistance and mechanical strength of the W coated Cu matrix were also measured. It is concluded that in double-glow plasma, W coated Cu can be facilely prepared. It is noticed that the treatment temperature heavily dominates the properties of the W-Cu composite.

  6. The chemically synthesized ageladine A-derivative LysoGlow84 stains lysosomes in viable mammalian brain cells and specific structures in the marine flatworm Macrostomum lignano.

    Science.gov (United States)

    Mordhorst, Thorsten; Awal, Sushil; Jordan, Sebastian; Petters, Charlotte; Sartoris, Linda; Dringen, Ralf; Bickmeyer, Ulf

    2015-02-11

    Based on the chemical structure and the known chemical synthesis of the marine sponge alkaloid ageladine A, we synthesized the ageladine A-derivative 4-(naphthalene-2-yl)-1H-imidazo[4,5-c]pyridine trifluoroacetate (LysoGlow84). The two-step synthesis started with the Pictet-Spengler reaction of histamine and naphthalene-2-carbaldehyde to a tetrahydropyridine intermediate, which was dehydrogenated with activated manganese (IV) oxide to LysoGlow84. Structure and purity of the synthesized LysoGlow84 were confirmed by NMR spectroscopy and mass spectrometry. The fluorescence intensity emitted by LysoGlow84 depended strongly on the pH of the solvent with highest fluorescence intensity recorded at pH 4. The fluorescence maximum (at 315 nm excitation) was observed at 440 nm. Biocompatibility of LysoGlow84 was investigated using cultured rat brain astrocytes and the marine flatworm Macrostomum lignano. Exposure of the astrocytes for up to 6 h to micromolar concentrations of LysoGlow84 did not compromise cell viability, as demonstrated by several viability assays, but revealed a promising property of this compound for staining of cellular vesicles. Conventional fluorescence microscopy as well as confocal scanning microscopy of LysoGlow84-treated astrocytes revealed co-localization of LysoGlow84 fluorescence with that of LysoTracker® Red DND-99. LysoGlow84 stained unclear structures in Macrostomum lignano, which were identified as lysosomes by co-staining with LysoTracker. Strong fluorescence staining by LysoGlow84 was further observed around the worms' anterior gut and the female genital pore which were not counterstained by LysoTracker Red. Thus, LysoGlow84 is a new promising dye that stains lysosomes and other acidic compartments in cultured cells and in worms.

  7. The Chemically Synthesized Ageladine A-Derivative LysoGlow84 Stains Lysosomes in Viable Mammalian Brain Cells and Specific Structures in the Marine Flatworm Macrostomum lignano

    Directory of Open Access Journals (Sweden)

    Thorsten Mordhorst

    2015-02-01

    Full Text Available Based on the chemical structure and the known chemical synthesis of the marine sponge alkaloid ageladine A, we synthesized the ageladine A-derivative 4-(naphthalene-2-yl-1H-imidazo[4,5-c]pyridine trifluoroacetate (LysoGlow84. The two-step synthesis started with the Pictet-Spengler reaction of histamine and naphthalene-2-carbaldehyde to a tetrahydropyridine intermediate, which was dehydrogenated with activated manganese (IV oxide to LysoGlow84. Structure and purity of the synthesized LysoGlow84 were confirmed by NMR spectroscopy and mass spectrometry. The fluorescence intensity emitted by LysoGlow84 depended strongly on the pH of the solvent with highest fluorescence intensity recorded at pH 4. The fluorescence maximum (at 315 nm excitation was observed at 440 nm. Biocompatibility of LysoGlow84 was investigated using cultured rat brain astrocytes and the marine flatworm Macrostomum lignano. Exposure of the astrocytes for up to 6 h to micromolar concentrations of LysoGlow84 did not compromise cell viability, as demonstrated by several viability assays, but revealed a promising property of this compound for staining of cellular vesicles. Conventional fluorescence microscopy as well as confocal scanning microscopy of LysoGlow84-treated astrocytes revealed co-localization of LysoGlow84 fluorescence with that of LysoTracker® Red DND-99. LysoGlow84 stained unclear structures in Macrostomum lignano, which were identified as lysosomes by co-staining with LysoTracker. Strong fluorescence staining by LysoGlow84 was further observed around the worms’ anterior gut and the female genital pore which were not counterstained by LysoTracker Red. Thus, LysoGlow84 is a new promising dye that stains lysosomes and other acidic compartments in cultured cells and in worms.

  8. Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki, E-mail: wagatuma@imr.tohoku.ac.jp

    2011-11-15

    A Boltzmann plot for many iron atomic lines having excitation energies of 3.3-6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3-4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas. - Highlights: Black-Right-Pointing-Pointer This paper shows the excitation mechanism of Fe I lines from a glow discharge plasma. Black-Right-Pointing-Pointer A Boltzmann distribution is studied among iron lines of various excitation levels. Black-Right-Pointing-Pointer We find an overpopulation of the high-lying energy levels from the normal distribution. Black-Right-Pointing-Pointer It is caused through Penning-type collision of iron atom with argon metastable atom.

  9. Cathodic contact glow discharge electrolysis: its origin and non-faradaic chemical effects

    Science.gov (United States)

    Gupta, Susanta K. Sen; Singh, Rajshree

    2017-01-01

    Normal electrolysis (NE), at sufficiently high voltages, breaks down and undergoes a transition to a phenomenon called contact glow discharge electrolysis (CGDE) in which a sheath of glow discharge plasma encapsulates one of the electrodes, the anode or the cathode. The chemical effects of CGDE are highly non-faradaic e.g. a mixture of H2 and H2O2 plus O2 each in excess of the Faraday law value is liberated at the glow discharge plasma electrode from an aqueous electrolyte solution. Studies of cathodic CGDE, particularly its origin and chemical effects, in comparison to those of anodic CGDE have received significantly less attention and have not been studied in detail. The present paper is an attempt towards elucidation of the mechanisms of the growth of cathodic CGDE during NE and its non-faradaic chemical effects. The findings of the study have led to the inference that emission of secondary electrons from the metal cathode with sufficient kinetic energies, vaporization of the electrolyte solvent in the vicinity of the cathode surface induced by Joule heating and the onset of hydrodynamic instabilities in local vaporization contribute to the generation of the plasma at the cathode during NE. The findings have further shown that non-faradaic yields of CGDE at the cathode originate from energy transfer processes in two reaction zones: a plasma phase reaction zone around the cathode which accounts for ~75% of the yields, and a liquid phase reaction zone near the plasma-catholyte solution interface accounting for the remaining ~25% of the yields.

  10. Synthesis and TL glow curve analysis of BaSO{sub 4}:Eu,Dy phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Rangeela Devi, Y. [Department of Physics, Manipur University, Canchipur, Imphal 795003 (India); Pachhunga University College, Aizawl, Mizoram (India); Dorendrajit Singh, S., E-mail: dorendrajit@yahoo.co.in [Department of Physics, Manipur University, Canchipur, Imphal 795003 (India)

    2012-06-15

    The polycrystalline samples of Ba{sub 1-x-y}SO{sub 4}:Eu{sub x},Dy{sub y} (0{<=}x{<=}1, 0{<=}y{<=}1) have been prepared using the chemical co-precipitation technique. The thermoluminescence (TL) sensitivity of the samples have been found changing with the value of x and y and the highest TL intensity is for Ba{sub 96}SO{sub 4}:Eu{sub 02},Dy{sub 02}. The sample has been characterised by x-ray diffraction (XRD). The samples are found to have orthorhombic structure. For TL analysis Ba{sub 96}SO{sub 4}:Eu{sub 02},Dy{sub 02} is annealed at different temperatures ranging from 873 to 1173 K. Kinetic parameters of all the TL glow curves of Ba{sub 1-x-y}SO{sub 4}:Eu{sub x},Dy{sub y} for different values of x and y and also for the TL glow curves Ba{sub 96}SO{sub 4}:Eu{sub 02},Dy{sub 02} annealed at different temperatures have been found out using computerised glow curve deconvolution (CGCD) method. The activation energy for the most intense TL peak at (444-453 K) is found out to be 1.26 eV and order of kinetics is 1.35. - Highlights: Black-Right-Pointing-Pointer TL study of BaSO{sub 4}:Eu,Dy is reported for the first time. Black-Right-Pointing-Pointer The kinetic parameters are evaluated by CGCD. Black-Right-Pointing-Pointer Effect of concentration, annealing temperature and dose response curve discussed.

  11. New historical records and relationships among 14C production rates, abundance and color of low latitude auroras and sunspot abundance

    Science.gov (United States)

    Abbott, Dallas; Juhl, Robert

    2016-12-01

    Incursions of high-energy particles from space, specifically solar energetic particles and galactic cosmic rays, have significant effects on the Earth, including disruption of the Earth's magnetic field, generation of electric fields strong enough to damage electronic devices as well as the production of auroras at low-latitudes, within 45° of the magnetic equator. We examine the relationships among 14C production, auroral abundance, auroral color and sunspot abundance using existing data supplemented by a new dataset. The new dataset, based on Chinese and Korean records from A.D. 1100-1700, includes 46 new or revised records of sunspots and 279 records of low-latitude auroras. Low-latitude auroras are predominantly red (66%, 835 events) with lesser proportions of white (20%, 253 events) and black auroras (6%, 67 events). All other auroral colors (green, yellow, multicolored, blue and purple) aggregate to a total of 100 events (8%). Overall, white auroras are more frequent during times of higher 14C production. We use two empirical methods of evaluating the flux of high-energy particles: modeled peaks and lows in 14C production and peaks and lows in the 14C calibration curve. We find that comparison to modeled 14C production gives significant results. White auroras are significantly more abundant (98% probability) at times of high production of 14C. Red auroras are somewhat more abundant (88% probability) at times of low production of 14C. The abundances of black, multicolored, green, yellow, and blue auroras between times of low and high 14C production are not significantly different. Violet/purple auroras are significantly more abundant (98% probability) at times of low 14C production. The positive correlation of violet/purple auroras with times of low14C production rate and the lack of correlation of blue auroras with times of high14C production is surprising, for this portion of the visible spectrum contains strong emission lines and some lines with high

  12. Degradation of Chloroanilines in Aqueous Solution by Contact Glow Discharge Electrolysis

    Institute of Scientific and Technical Information of China (English)

    高锦章; 胡中爱; 陆泉芳; 纳鹏君; 陈平; 刘永军; 俞洁

    2003-01-01

    Contact glow discharge electrolysis of some chloroanilines in sodium sulfate was investigated in different initial concentrations. Each of them underwent the dechlorination, deamination through oxidative degradation, and were eventually decomposed into hydrogen carbonate and carbon dioxide. It was testified that the chlorine atom and amidogen could be transformed into chloride ion and nitrite ion, respectively. Fe2+ has a remarkable catalytic effect on the degradation of them. On the basis of the detailed analysis of the intermediate products and kinetic behaviors, the reaction pathway was proposed, in which the attack of hydroxyl radical on the benzene ring of starting material might be a key step.

  13. Formation and dynamics of nano-particles in a stratified spherical glow discharge

    Science.gov (United States)

    Sakhapov, S. Z.; Fedoseev, A. V.; Sukhinin, G. I.; Novopashin, S. A.

    2015-04-01

    The formation of clouds of dust nano-particles in a spherical dc glow discharge in ethanol was observed. Nano-particles were formed in a process of coagulation of ethanol dissociation products in a plasma of gas discharge. During the process the particles were captured into clouds in the electric potential wells of the strong striations of a spherical discharge. Periodically, the cloud of nano-particles experienced some sudden instability (explosion), and started to move to the cathode at high velocity. It was proved that the velocity of the particle clouds was an exponentially decaying function of time as in the case of dissipative dust solitary waves.

  14. Relativistic feedback models of terrestrial gamma-ray flashes and gamma-ray glows

    Science.gov (United States)

    Dwyer, J. R.

    2015-12-01

    Relativistic feedback discharges, also known as dark lightning, are capable of explaining many of the observed properties of terrestrial gamma-ray flashes (TGFs) and gamma-ray glows, both created within thunderstorms. During relativistic feedback discharges, the generation of energetic electrons is self-sustained via the production of backward propagating positrons and back-scattered x-rays, resulting in very larges fluxes of energetic radiation. In addition, ionization produces large electric currents that generate LF/VLF radio emissions and eventually discharge the electric field, terminating the gamma-ray production. In this presentation, new relativistic feedback model results will be presented and compared to recent observations.

  15. Stabilization of a cold cathode electron beam glow discharge for surface treatment

    Energy Technology Data Exchange (ETDEWEB)

    Mingolo, N.; Gonzalez, C.R. [Lab. de Haces Dirigidos, Depto. de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, 1063 Buenos Aires (Argentina); Martinez, O.E. [Lab. de Electronica Cuantica, Depto. de Fisica, Universidad de Buenos Aires, Pabellon 1, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Rocca, J.J. [Department of Electrical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States)

    1997-10-01

    We have demonstrated that the reproducibility of electron beam pulses generated by a high power, cold cathode glow discharge is greatly improved by adding a small continuous keep-alive discharge current. A current of the order of 200 {mu}A was found to limit the shot to shot current variation to within 1.5{percent}. This stabilization in turn reduces by an order of magnitude the fluctuations of the energy density deposited on the target, demonstrating a reliable energy source for surface treatment. {copyright} {ital 1997 American Institute of Physics.}

  16. Radial Evolution of the Atmospheric Pressure Glow Discharge in Helium Controlled by Dielectric Barrier

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yuan-Tao; WANG De-Zhen; WANG Yan-Hui; LIU Cheng-Sen

    2005-01-01

    @@ The radial evolution of atmospheric pressure glow discharge in helium is presented by numerical simulation. The calculations reveal the mechanism of two current peaks per half cycle. The first breakdown occurs firstly in the central region of the electrode, and then spreads to the edge, while the second breakdown ignites at the periphery firstly, and then propagates toward the discharge central region. The simulations indicate that radial electric fields and radial sheath play an important role in the evolution of the second peak. These results agree fundamentally with the experimental observations.

  17. Study of stability of dc glow discharges with the use of Comsol Multiphysics software

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, P G C; Benilov, M S; Faria, M J [Departamento de Fisica, Universidade da Madeira, Largo do Municipio, 9000 Funchal (Portugal)

    2011-10-19

    Stability of different axially symmetric modes of current transfer in dc glow discharges is investigated in the framework of the linear stability theory with the use of Comsol Multiphysics software. Conditions of current-controlled microdischarges in xenon are treated as an example. Both real and complex eigenvalues have been detected, meaning that perturbations can vary with time both monotonically and with oscillations. In general, results given by the linear stability theory confirm intuitive concepts developed in the literature and conform to the experiment. On the other hand, suggestions are provided for further experimental and theoretical work.

  18. Reduction of TiO2 with hydrogen cold plasma in DC pulsed glow discharge

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-wen; DING Wei-zhong; LU Xiong-gang; GUO Shu-qiang; XU Kuang-di

    2005-01-01

    The reduction of TiO2 to Ti2O3 with hydrogen cold plasma generated by a DC pulsed glow discharge was realized under 2 500 Pa at 1 233 K. Only a little of Ti10O19 and Ti9O17 was detected for using molecular hydrogen.Enhancement effects of hydrogen cold plasma on the reduction were discussed in terms of thermodynamic coupling,kinetics and plasma sheath. The exited hydrogen species are considered more effective reducing agents. It is instructive to reduce refractory oxides with plasma hydrogen at the reduced temperature.

  19. Analysis of green fluorescent protein bioluminescence in vivo and in vitro using a glow discharge

    Science.gov (United States)

    Hernández, L.; Mandujano, L. A.; Cuevas, J.; Reyes, P. G.; Osorio-González, D.

    2015-03-01

    The discovery of fluorescent proteins has been a revolution in cell biology and related sciences because of their many applications, mainly emphasizing their use as cellular markers. The green fluorescent protein (GFP) is one of the most used as it requires no cofactors to generate fluorescence and retains this property into any organism when it is expressed by recombinant DNA techniques, which is a great advantage. In this work, we analyze the emission spectra of recombinant green fluorescent protein in vivo and in vitro exposed to a glow discharge plasma of nitrogen in order to relate electron temperature to fluorescence intensity.

  20. Surface modification of austenitic steel by various glow-discharge nitriding methods

    Directory of Open Access Journals (Sweden)

    Tomasz Borowski

    2015-09-01

    Full Text Available Recent years have seen intensive research on modifying glow-discharge nitriding processes. One of the most commonly used glow-discharge methods includes cathodic potential nitriding (conventional method, and active screen plasma nitriding. Each of these methods has a number of advantages. One very important, common feature of these techniques is full control of the microstructure, chemical and phase composition, thickness and the surface topography of the layers formed. Another advantage includes the possibility of nitriding such materials as: austenitic steels or nickel alloys, i.e. metallic materials which do not diffuse nitrogen as effectively as ferritic or martensitic steels. However, these methods have some disadvantages as well. In the case of conventional plasma nitriding, engineers have to deal with the edge effect, which makes it difficult to use this method for complexly shaped components. In turn, in the case of active screen plasma nitriding, the problem disappears. A uniform, smooth layer forms, but is thinner, softer and is not as resistant to friction compared to layers formed using the conventional method. Research is also underway to combine these methods, i.e. use an active screen in conventional plasma nitriding at cathodic potential. However, there is a lack of comprehensive data presenting a comparison between these three nitriding processes and the impact of pulsating current on the formation of the microstructure and functional properties of austenitic steel surfaces. The article presents a characterisation of nitrided layers produced on austenitic X2CrNiMo17-12-2 (AISI 316L stainless steel in the course of glow-discharge nitriding at cathodic potential, at plasma potential and at cathodic potential incorporating an active screen. All processes were carried out at 440 °C under DC glow-discharge conditions and in 100 kHz frequency pulsating current. The layers were examined in terms of their microstructure, phase and

  1. Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

    Science.gov (United States)

    Li, Guo; Li, He-Ping; Wang, Li-Yan; Wang, Sen; Zhao, Hong-Xin; Sun, Wen-Ting; Xing, Xin-Hui; Bao, Cheng-Yu

    2008-06-01

    Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

  2. Irregular-regular-irregular mixed mode oscillations in a glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Sabuj, E-mail: sabuj.ghosh@saha.ac.in; Shaw, Pankaj Kumar, E-mail: pankaj.shaw@saha.ac.in; Saha, Debajyoti, E-mail: debajyoti.saha@saha.ac.in; Janaki, M. S., E-mail: ms.janaki@saha.ac.in; Iyengar, A. N. Sekar, E-mail: ansekar.iyengar@saha.ac.in [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata-700064 (India)

    2015-05-15

    Floating potential fluctuations of a glow discharge plasma are found to exhibit different kinds of mixed mode oscillations. Power spectrum analysis reveals that with change in the nature of the mixed mode oscillation (MMO), there occurs a transfer of power between the different harmonics and subharmonics. The variation in the chaoticity of different types of mmo was observed with the study of Lyapunov exponents. Estimates of correlation dimension and the Hurst exponent suggest that these MMOs are of low dimensional nature with an anti persistent character. Numerical modeling also reflects the experimentally found transitions between the different MMOs.

  3. Antitumor Activity of KW-2450 Against Triple-Negative Breast Cancer by Inhibiting Aurora A and B Kinases

    OpenAIRE

    Kai, Kazuharu; Kondo, Kimie; Wang, Xiaoping; Xie, Xuemei; Pitner, Mary K.; Reyes, Monica E.; Torres-Adorno, Angie M.; Masuda,Hiroko; Hortobagyi, Gabriel N.; Bartholomeusz, Chandra; Saya, Hideyuki; Tripathy, Debu; Sen, Subrata; Ueno, Naoto T

    2015-01-01

    Currently, no targeted drug is available for triple-negative breast cancer (TNBC), an aggressive breast cancer that does not express estrogen receptor, progesterone receptor, or HER2. TNBC has high mitotic activity, and since Aurora A and B mitotic kinases drive cell division and are overexpressed in tumors with a high mitotic index, we hypothesized that inhibiting Aurora A and B produces a significant antitumor effect in TNBC. We tested this hypothesis by determining the antitumor effects of...

  4. AGING EFFECTS OF REPEATEDLY GLOW-DISCHARGED POLYETHYLENE - INFLUENCE ON CONTACT-ANGLE, INFRARED-ABSORPTION, ELEMENTAL SURFACE-COMPOSITION, AND SURFACE-TOPOGRAPHY

    NARCIS (Netherlands)

    VANDERMEI, HC; STOKROOS, [No Value; SCHAKENRAAD, JM; BUSSCHER, HJ

    1991-01-01

    Aging effects of repeatedly oxygen glow-discharged polyethylene surfaces were determined by water contact angle measurements, infrared (IR) spectroscopy, X-ray photoelectron (XPS) spectroscopy, and surface topography determination. Glow-discharged surfaces were stored at room temperature and in liqu

  5. Glycogen synthase kinase 3 β activity is required for hBora/Aurora A-mediated mitotic entry.

    Science.gov (United States)

    Lee, Yu-Cheng; Liao, Po-Chi; Liou, Yih-Cherng; Hsiao, Michael; Huang, Chi-Ying; Lu, Pei-Jung

    2013-03-15

    The synthesis and degradation of hBora is important for the regulation of mitotic entry and exist. In G 2 phase, hBora can complex with Aurora A to activate Plk1 and control mitotic entry. However, whether the post-translational modification of hBora is relevant to the mitotic entry still unclear. Here, we used the LC-MS/MS phosphopeptide mapping assay to identify 13 in vivo hBora phosphorylation sites and characterized that GSK3β can interact with hBora and phosphorylate hBora at Ser274 and Ser278. Pharmacological inhibitors of GSK3β reduced the retarded migrating band of hBora in cells and diminished the phosphorylation of hBora by in vitro kinase assay. Moreover, as well as in GSK3β activity-inhibited cells, specific knockdown of GSK3β by shRNA and S274A/S278 hBora mutant-expressing cells also exhibited the reduced Plk1 activation and a delay in mitotic entry. It suggests that GSK3β activity is required for hBora-mediated mitotic entry through Ser274 and Ser278 phosphorylation.

  6. Anticipated Guilt for not Helping and Anticipated Warm Glow for Helping are Differently Impacted by Personal Responsibility to Help

    Directory of Open Access Journals (Sweden)

    Arvid Erlandsson

    2016-09-01

    Full Text Available One important motivation for people behaving prosocially is that they want to avoid negative and obtain positive emotions. In the prosocial behavior literature however, the motivations to avoid negative emotions (e.g. guilt and to approach positive emotions (e.g. warm glow are rarely separated, and sometimes even aggregated into a single mood-management construct. The aim of this study was to investigate whether anticipated guilt if not helping and anticipated warm glow if helping are influenced similarly or differently when varying situational factors related to personal responsibility to help. Helping scenarios were created and pilot tests established that each helping scenario could be formulated both in a high-responsibility version and in a low-responsibility version. In Study 1 participants read high-responsibility and low-responsibility helping scenarios, and rated either their anticipated guilt if not helping or their anticipated warm glow if helping (i.e. separate evaluation. Study 2 was similar but here participants rated both their anticipated guilt if not helping and their anticipated warm glow if helping (i.e. joint evaluation. Anticipated guilt was clearly higher in the high-responsibility versions, but anticipated warm glow was unaffected (in Studies 1a and 1b, or even higher in the low-responsibility versions (Study 2. In Studies 3 (where anticipated guilt and warm glow were evaluated separately and 4 (where they were evaluated jointly, personal responsibility to help was manipulated within-subjects. Anticipated guilt was again constantly higher in the high-responsibility versions but for many types of responsibility-manipulations, anticipated warm glow was higher in the low-responsibility versions. The results suggest that we anticipate guilt if not fulfilling our responsibility but that we anticipate warm glow primarily when doing over and beyond our responsibility. We argue that future studies investigating motivations for

  7. Visualizing ignition and combustion of methanol mixtures in a diesel engine; Methanol funmu no glow chakka to nensho no kashika

    Energy Technology Data Exchange (ETDEWEB)

    Inomoto, Y.; Harada, T.; Kusaka, J.; Daisho, Y.; Kihara, R.; Saito, T. [Waseda University, Tokyo (Japan)

    1997-10-01

    A glow-assisted ignition system tends to suffer from poor ignitability and slow flame propagation at low load in a direct-injection diesel engine fueled with methanol. To investigate the ignition process and improve such disadvantages, methanol sprays, their ignition and flames were visualized at high pressures and temperatures using a modified two-stroke engine. The results show that parameters influencing ignition, the location of a glow-plug, swirl level, pressure and temperature are important. In addition, a full kinetics calculation was conducted to predict the delay of methanol mixture ignition by taking into account 39 chemical species and 157 elementary reactions. 3 refs., 9 figs.

  8. Multi-spectral simultaneous diagnosis of Saturns aurorae throughout a planetary rotation

    CERN Document Server

    Lamy, L; Pryor, W; Gustin, J; Badman, S V; Melin, H; Stallard, T; Mitchell, D G; Brandt, P C

    2013-01-01

    From the 27th to the 28th January 2009, the Cassini spacecraft remotely acquired combined observations of Saturns southern aurorae at radio, ultraviolet and infrared wavelengths, while monitoring ion injections in the middle magnetosphere from energetic neutral atoms. Simultaneous measurements included the sampling of a full planetary rotation, a relevant timescale to investigate auroral emissions driven by processes internal to the magnetosphere. In addition, this interval coincidently matched a powerful substorm-like event in the magnetotail, which induced an overall dawnside intensification of the magnetospheric and auroral activity. We comparatively analyze this unique set of measurements to reach a comprehensive view of kronian auroral processes over the investigated timescale. We identify three source regions in atmospheric aurorae, including a main oval associated with the bulk of Saturn Kilometric Radiation (SKR), together with polar and equatorward emissions. These observations reveal the co-existenc...

  9. 安捷伦与Aurora SFC合作开发HPLC/SFC复合系统

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    安捷伦科技公司和Aurora SFC系统公司近日宣布,安捷伦将为Aurora SFC Fusion A5Tm的开发提供技术支持,将现有的HPLC系统转换成SFC系统。SFC Fusion A5支持安捷伦1100和1200系列液相色谱系统,以及1200系列RRLC系统。安捷伦液相色谱高级市场部经理Stefan Schuette表示:“随着药物开发法规要求日益严格,

  10. Long-Term Trends and Gleissberg Cycles in Aurora Borealis Records (1600 - 2015)

    Science.gov (United States)

    Vázquez, M.; Vaquero, J. M.; Gallego, M. C.; Roca Cortés, T.; Pallé, P. L.

    2016-02-01

    The long-term spatial and temporal variation of aurora borealis events from 1600 to the present were studied using catalogues and other records of these phenomena. Geographic and geomagnetic coordinates were assigned to approximately 45 000 auroral events with more than 160 000 observations. They were analysed separately for three large-scale areas: i) Europe and North Africa, ii) North America, and iii) Asia. Variations in the cumulative numbers of auroral events with latitude (in both geographic and geomagnetic coordinates) were used to distinguish between the two main solar sources: coronal mass ejections and high-speed streams from coronal holes. We find significant long-term variations in the space-time distribution of auroras. We mainly identify these with four Gleissberg solar activity cycles whose overall characteristics we examine. The Asian observations are crucial in this context, and therefore merit further studies and verifications.

  11. Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence

    CERN Document Server

    Hallinan, G; Cotter, G; Bourke, S; Harding, L K; Pineda, J S; Butler, R P; Golden, A; Basri, G; Doyle, J G; Kao, M M; Berdyugina, S V; Kuznetsov, A; Rupen, M P; Antonova, A

    2015-01-01

    Aurorae are detected from all the magnetized planets in our Solar System, including Earth. They are powered by magnetospheric current systems that lead to the precipitation of energetic electrons into the high-latitude regions of the upper atmosphere. In the case of the gas-giant planets, these aurorae include highly polarized radio emission at kilohertz and megahertz frequencies produced by the precipitating electrons, as well as continuum and line emission in the infrared, optical, ultraviolet and X-ray parts of the spectrum, associated with the collisional excitation and heating of the hydrogen-dominated atmosphere. Here we report simultaneous radio and optical spectroscopic observations of an object at the end of the stellar main sequence, located right at the boundary between stars and brown dwarfs, from which we have detected radio and optical auroral emissions both powered by magnetospheric currents. Whereas the magnetic activity of stars like our Sun is powered by processes that occur in their lower a...

  12. The Mars aurora: UV detections and in situ electron flux measurements

    Science.gov (United States)

    Gérard, J.-C.; Soret, L.; Lundin, R.; Libert, L.; Stiepen, A.; Radioti, A.; Bertaux, J.-L.; Shematovich, V. I.; Bisikalo, D.

    2015-10-01

    A detailed search through the database of the SPICAM instrument on board Mars Express made it possible to identify 16 signatures of the CO Cameron and CO2+ doublet auroral emissions. These auroral UV signatures are all located in the southern hemisphere in the vicinity of the statistical boundary between open and closed field lines. The energy spectrum of the energetic electrons was simultaneously measured by ASPERA-3/ELS at higher altitude. The UV aurora is generally shifted from the region of enhanced downward electron energy flux by a few to several tens of degrees of latitude, suggesting that precipitation occurs in magnetic cusp like structures along inclined magnetic field lines. The ultraviolet brightness shows no proportionality with the electron flux measured at the spacecraft altitude. The Mars aurora appears as a sporadic short-lived feature. Results of Monte Carlo simulations will be compared with the observed brightness of the Cameron and CO2+ bands.

  13. Feedback control of chromosome separation by a midzone Aurora B gradient

    Science.gov (United States)

    Pereira, António J.; Aguiar, Paulo; Lampson, Michael A.; Maiato, Helder

    2017-01-01

    Accurate chromosome segregation during mitosis requires the physical separation of sister chromatids before nuclear envelope reassembly (NER). However, how these two processes are coordinated remains unknown. Here, we identified a conserved feedback control mechanism that delays chromosome decondensation and NER in response to incomplete chromosome separation during anaphase. A midzone-associated Aurora B gradient was found to monitor chromosome position along the division axis and to prevent premature chromosome decondensation by retaining Condensin I. PP1/PP2A phosphatases counteracted this gradient and promoted chromosome decondensation and NER. Thus, an Aurora B gradient appears to mediate a surveillance mechanism that prevents chromosome decondensation and NER until effective separation of sister chromatids is achieved. This allows the correction and reintegration of lagging chromosomes in the main nuclei before completion of NER. PMID:24925910

  14. On the Connection Between Solar Activity and Low-Latitude Aurorae in the Period 1715 - 1860

    Science.gov (United States)

    Vázquez, M.; Vaquero, J. M.; Curto, J. J.

    2006-11-01

    Observations of aurorae borealis at low latitudes are very rare and are clearly associated with strong geomagnetic storms. Morphologically, they are characterized by a diffuse red colour with no rapid motions. The main aim of this paper is to analyse two hitherto ignored aurorae that were observed at two low-latitude sites, Tenerife (28°N 18°W) and Mexico City (19°N 99°W), in 1770 and 1789, respectively. These observations can give supplementary information about the level of solar activity at those times where direct solar observations were rather scarce. Studying also the behaviour of the heliosphere during this period using different proxies, we find that the open magnetic field better describes auroral occurrences. The variation over time in geomagnetic latitude at the two sites is also calculated.

  15. MI Coupling Processes in the Regions of Diffuse Aurora: Magnetospheric Outlook

    Science.gov (United States)

    Khazanov, George V.; Glocer, Alex; Sibeck, David

    2016-04-01

    In this talk we present the solution of the Boltzmann-Landau kinetic equation that uniformly describes the entire electron distribution function in the diffuse aurora. The calculation includes the affiliated production of secondary electrons and their energy interplay in the magnetosphere and two conjugated ionospheres. This solution starts with the primary injection of plasma sheet electrons via both electron cyclotron harmonic waves and whistler mode chorus waves to the loss cone, and includes their subsequent multiple atmospheric reflections between the two magnetically conjugated ionospheres. It is demonstrated that magnetosphere-ionosphere coupling is the key element in the formation of electron distribution function in the region of diffuse aurora at the magnetospheric altitudes.

  16. Aurora kinase inhibitors: which role in the treatment of chronic myelogenous leukemia patients resistant to imatinib?

    Directory of Open Access Journals (Sweden)

    Giovanni Martinelli

    2009-02-01

    Full Text Available At present, there are no compounds in clinical development in the field of chronic myeloid leukemia (CML or Philadelphia-positive (Ph+ acute lymphoblastic leukemia (ALL that have been documented to harbor significant activity against the imatinib-resistant T315I mutation. Recent reports on the pre-clinical activity of some emerging tyrosine kinase inhibitors such as ON012380, VX-680 and PHA-739358 promise possible clinical efficacy against this specific Bcr-Abl mutant form. Here, we focus on the role of aurora kinase inhibitor VX-680 and PHA-739358 in blocking the leukemogenic pathways driven by wild-type and T315I-Bcr-Abl in CML or Ph+ ALL by reviewing recent research evidence. We also discuss the possibility of employing aurora kinase inhibitors as a promising new therapeutic approach in the treatment of CML and Ph+ ALL patients resistant to first and second generation TK inhibitors.

  17. New Treatment of Medullary and Papillary Human Thyroid Cancer: Biological Effects of Hyaluronic Acid Hydrogel Loaded With Quercetin Alone or in Combination to an Inhibitor of Aurora Kinase.

    Science.gov (United States)

    Quagliariello, Vincenzo; Armenia, Emilia; Aurilio, Caterina; Rosso, Francesco; Clemente, Ottavia; de Sena, Gabriele; Barbarisi, Manlio; Barbarisi, Alfonso

    2016-08-01

    The aim of this paper is based on the use of a hyaluronic acid hydrogel of Quercetin tested alone and in combination to an inhibitor of Aurora Kinase type A and B (SNS-314) on human medullary and papillary thyroid cancer cells. Biological investigations were focused on the cellular uptake of the hydrogel, cell viability, antioxidant, and cytokines secretion studies. Quercetin delivered from hydrogel show a time and CD44 dependent interaction with both cell lines with significant anti-inflammatory effects. Combination of Quercetin and SNS-314 leads to a synergistic cytotoxic effect on medullary TT and papillary BCPAP cell lines with a significant reduction of the IC50 value. These results, highlights the importance of synergistic effect of the hyaluronic acid hydrogel of Quercetin with SNS-314 in the regulation of human thyroid cancer cell proliferation and emphasize the anti-tumor activity of these molecules. J. Cell. Physiol. 231: 1784-1795, 2016. © 2015 Wiley Periodicals, Inc.

  18. Experimental measurements of the hollow cathode DC glow discharge parameters in Ar and He plasmas

    Science.gov (United States)

    Omrani, M.; Amrollahi, R.; Iraji, D.

    2016-12-01

    In this article, we focus on some of the fundamental parameters of SS316L hollow cathode glow discharge. Four SS316L samples are placed at different locations on the cathode surface and the current passed through them is measured in Ar and He glow discharge plasmas. The wall current densities of Ar and He are in the range of 8-25 µA cm-2 and 8-35 µA cm-2, respectively. Results also show that with decreasing working pressure, the ion flux and current density distribution on the wall surface becomes more uniform. The ion flux of the Ar and He is in the range of 1013 to 1014 ~\\text{ion} \\text{c}{{\\text{m}}-2} . Total energy losses of Ar and He are measured at the pressure range of 1.4-5.5  ×  10-2 torr and 3.2-7.1  ×  10-1, respectively. In both Ar and He, total energy losses decreased with increasing pressure. The secondary electron emission coefficients of Ar and He, which are evaluated for the hallow cathode configuration, are about 0.42 and 0.26, respectively, and are higher in comparison with the plate cathode configuration.

  19. Decomposition of toluene in a steady-state atmospheric-pressure glow discharge

    Science.gov (United States)

    Trushkin, A. N.; Grushin, M. E.; Kochetov, I. V.; Trushkin, N. I.; Akishev, Yu. S.

    2013-02-01

    Results are presented from experimental studies of decomposition of toluene (C6H5CH3) in a polluted air flow by means of a steady-state atmospheric pressure glow discharge at different water vapor contents in the working gas. The experimental results on the degree of C6H5CH3 removal are compared with the results of computer simulations conducted in the framework of the developed kinetic model of plasma chemical decomposition of toluene in the N2: O2: H2O gas mixture. A substantial influence of the gas flow humidity on toluene decomposition in the atmospheric pressure glow discharge is demonstrated. The main mechanisms of the influence of humidity on C6H5CH3 decomposition are determined. The existence of two stages in the process of toluene removal, which differ in their duration and the intensity of plasma chemical decomposition of C6H5CH3 is established. Based on the results of computer simulations, the composition of the products of plasma chemical reactions at the output of the reactor is analyzed as a function of the specific energy deposition and gas flow humidity. The existence of a catalytic cycle in which hydroxyl radical OH acts a catalyst and which substantially accelerates the recombination of oxygen atoms and suppression of ozone generation when the plasma-forming gas contains water vapor is established.

  20. Investigation of helium ion production in constricted direct current plasma ion source with layered-glows

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yuna [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Chung, Kyoung-Jae, E-mail: jkjlsh1@snu.ac.kr [Center for Advance Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Park, Yeong-Shin [Samsumg Electronics Co. Ltd., Gyeonggi 445-701 (Korea, Republic of); Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Center for Advance Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)

    2014-02-15

    Generation of helium ions is experimentally investigated with a constricted direct current (DC) plasma ion source operated at layered-glow mode, in which electrons could be accelerated through multiple potential structures so as to generate helium ions including He{sup 2+} by successive ionization collisions in front of an extraction aperture. The helium discharge is sustained with the formation of a couple of stable layers and the plasma ball with high density is created near the extraction aperture at the operational pressure down to 0.6 Torr with concave cathodes. The ion beam current extracted with an extraction voltage of 5 kV is observed to be proportional to the discharge current and inversely proportional to the operating pressure, showing high current density of 130 mA/cm{sup 2} and power density of 0.52 mA/cm{sup 2}/W. He{sup 2+} ions, which were predicted to be able to exist due to multiple-layer potential structure, are not observed. Simple calculation on production of He{sup 2+} ions inside the plasma ball reveals that reduced operating pressure and increased cathode area will help to generate He{sup 2+} ions with the layered-glow DC discharge.

  1. Charge mitigation techniques using glow and corona discharges for advanced gravitational wave detectors

    Energy Technology Data Exchange (ETDEWEB)

    Campsie, P; Cunningham, L; Hendry, M; Hough, J; Reid, S; Rowan, S; Hammond, G D, E-mail: p.campsie@physics.gla.ac.uk [SUPA , Institute for Gravitational Research, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)

    2011-11-07

    Charging of silica test masses in gravitational wave detectors could potentially become a significant low-frequency noise source for advanced detectors. Charging noise has already been observed and confirmed in the GEO600 detector and is thought to have been observed in one of the LIGO detectors. In this paper, two charge mitigation techniques using glow and corona discharges were investigated to create repeatable and robust procedures. The glow discharge procedure was used to mitigate charge under vacuum and would be intended to be used in the instance where an optic has become charged while the detector is in operation. The corona discharge procedure was used to discharge samples at atmospheric pressure and would be intended to be used to discharge the detector optics during the cleaning of the optics. Both techniques were shown to reduce both polarities of surface charge on fused silica to a level that would not limit advanced LIGO. Measurements of the transmission of samples that had undergone the charge mitigation procedures showed no significant variation in transmission, at a sensitivity of {approx} 200 ppm, in TiO{sub 2}-doped Ta{sub 2}O{sub 5}/SiO{sub 2} multi-layer coated fused silica.

  2. An Experimental Study on Atmospheric Pressure Glow Discharge in Different Gases

    Institute of Scientific and Technical Information of China (English)

    刘鹏; 詹如娟; 等

    2002-01-01

    Usually,the electrical breakdown of dielectric barrier discharge(DBD) at atmospheric pressure leads to a filamentary non-homogeneous discharge,However,it is also possible to obtain a diffuse DBD in homogeneous form,called atmospheric pressure glow discharge(APGD).We obtained a uniform APGD in helium and in the mixture of argon with alcohol,and studied the electrical characteristics of helium APGD.It if found that the relationship between discharge current and source frequency is different depending on the difference in gas gap when the applied voltage is kept constant.The discharge current shows an increasing trend with the increased frequency when gas gap is 0.8cm ,but the discharge current tends to decrease with the increased frequency when the gas gap increases.The discharge current always increases with the increased applied voltage when the source frequency is kept constant.We also observed a glow-like discharge in nitrogen at atmospheric pressure.

  3. Thermoluminescence glow curve deconvolution functions by continued fractions for different orders of kinetics

    Science.gov (United States)

    Flores-Llamas, H.; Gutiérrez-Tapia, C.

    2013-03-01

    The shape of the peaks in thermoluminescence (TL) dosimetry can be represented by the so-called temperature integral. In this paper, we present a very efficient method, based on a continued fraction approach to the incomplete gamma function, intended to calculate the overall temperature integral which includes the frequency factor ∝ T a . The single glow-peak algorithm for linear and exponential heating rates is derived. In the first case, the method provides a good approximation with a maximum relative error of 1.1×10-5 within the 0.1≤E/kT≤90 range in the case of a=0. It is shown that, in general, the method is efficient, converges quickly and can be adopted in the numerical fitting of glow lines in order to obtain the parameters relevant to TL. The utility of this approach is exemplified by adjusting the standard lithium flouride doped with magnesium and titanium (LiF): Mg, Ti (TLD-100) using five and six thermoluminescent peaks, determining that peak 6 is present and observable in the analysed spectrum. Finally, methods such as asymptotic expansion of the temperature integral by the asymptotic series approximation, the convergent series approximation, the Lagrange continued fraction approximation and a new obtained continued fraction approximation are compared with the method proposed here in the case of linear heating.

  4. Operation Mode on Pulse Modulation in Atmospheric Radio Frequency Glow Discharges

    Science.gov (United States)

    Zhang, Jie; Guo, Ying; Huang, Xiaojiang; Zhang, Jing; Shi, Jianjun

    2016-10-01

    The discharge operation regime of pulse modulated atmospheric radio frequency (RF) glow discharge in helium is investigated on the duty cycle and frequency of modulation pulses. The characteristics of radio frequency discharge burst in terms of breakdown voltage, alpha(α)-gamma(γ) mode transition voltage and current are demonstrated by the discharge current voltage characteristics. The minimum breakdown voltage of RF discharge burst was obtained at the duty cycle of 20% and frequency of 400 kHz, respectively. The α-γ mode transition of RF discharge burst occurs at higher voltage and current by reducing the duty cycle and elevating the modulation frequency before the RF discharge burst evolving into the ignition phase, in which the RF discharge burst can operate stably in the γ mode. It proposes that the intensity and stability of RF discharge burst can be improved by manipulating the duty cycle and modulation frequency in pulse modulated atmospheric RF glow discharge. supported by National Natural Science Foundation of China (Nos. 11475043 and 11375042)

  5. A Study on Helium Glow Discharge Cleaning in the HL- 1M Tokamak

    Institute of Scientific and Technical Information of China (English)

    王志文; 严东海; 王恩耀

    2002-01-01

    Based on the principle of ion-bombarded reemission and sputtering desorption, the Glow Discharge Cleaning with helium (GDC(He)) is an effective method for controlling the recycle of H on the chamber wall, Carbon(C), Oxygen(O) impurity and improving the wall conditioning in HL-1M tokamak. It is characterized by simplicity without magnet and safety, compared with Taylor Discharge Cleaning (TDC), Alternating current glow discharge Cleaning (AC), Electron Cyclotron Resonance-Discharge Cleaning (ECR-DC). Compared with bake-out degassing, the wall has a higher degassing rate during GDC(He) and a lower impurity concentration in vacuum chambers after GDC(He). Cleaning patterns have been developed dominantly for de-oxidization, decarbonization and de-hydrogenization. The cleaning parameters for H recycle on the wall are also presented. This paper mainly describes the GDC system along with its parameters, breakdown voltage, volt-ampere characteristic, the range of operation safe and suitable cleaning patterns in the HL-1M tokamak, finally concluding with some suggestions on HL-2A GDC.

  6. Charging of dust grains in a nonequilibrium plasma of a stratified glow discharge

    Science.gov (United States)

    Sukhinin, G. I.; Fedoseev, A. V.

    2007-12-01

    A theoretical model is presented that describes the charging of dust grains in the positive plasma column of a stratified glow dc discharge in argon. A one-dimensional self-consistent model is used to obtain axial profiles of the electric field, as well as the electron energy distribution function along the axis of the discharge tube. Radial profiles of the electric field are determined in the ambipolar diffusion approximation. It is assumed that, in the radial direction, the electron distribution function depends only on the total electron energy. Two-dimensional distributions of the discharge plasma parameters are calculated and used to determine the potential and charge of a test dust grain at a certain point within the discharge and the electrostatic forces acting on it. It is shown that the grain charge distribution depends strongly on the nonequilibrium electron distribution function and on the nonuniform distribution of the electric field in a stratified glow discharge. A discussion is presented on the suspension of dust grains, the separation of grains by size in the discharge striations, and a possible mechanism for the onset of vortex dust motion at the edge of a dust cloud.

  7. High-Energy Radiation from Thunderstorms with ADELE: TGFs, Steps, and Glows

    Science.gov (United States)

    Smith, David M.; Kelley, Nicole; Martinez-McKinney, Forest; Zhang, Zi Yan; Hazelton, Bryna; Grefenstette, Brian; Splitt, Michael; Lazarus, Steven; Ulrich, William; Levine, Steven; Dwyer, Joseph; Schaal, Meagan; Saleh, Ziad; Cramer, Eric; Rassoul, Hamid; Cummer, Steven; Lu, Gaopeng; Shao, Xuan-Min; Ho, Cheng; Blakeslee, Richard

    2011-01-01

    The biggest challenge in the study of high-energy processes in thunderstorms is getting a detector to the vicinity of the electrically active regions of a storm. The Airborne Detector for Energetic Lightning Emissions (ADELE) has been used to detect gamma rays from aircraft above storms and from a storm-chasing van on the ground. In August 2009, ADELE flew above Florida storms in a Gulfstream V jet, detecting the first terrestrial gamma-ray flash (TGF) seen from a plane and continuous glows of high-energy emission above thunderclouds. The presence of these glows suggests that a gradual process of relativistic runaway and feedback may help limit the total amount of charging in thunderstorms, in contrast to the traditional view that only lightning discharges compete with the charging process. The upper limits on TGF emission from intracloud and cloud-to-ground lightning from the ADELE flights demonstrated conclusively that a TGF of the sort seen from space is not associated with most lightning and not necessary to trigger it. In August 2010, observations from a van detected stepped-leader x-ray emission from at least four lightning strikes in ten days of operations. This mode of operation is therefore promising for future observations of the stepping process, although a more varied suite of instrumentation, in particular a flash-distance detector, would be useful. We will report on these results and on future possibilities for ADELE campaigns.

  8. Glow curves and the emission of flux grown BaFCl-Tb crystals

    Energy Technology Data Exchange (ETDEWEB)

    Somaiah, K.; Moinuddin, S.R.; Nambi, K.S.V.

    1987-09-01

    Flux-grown BaFCl crystals containing 0.5 mol % of terbium were irradiated at room temperature by ..gamma..-rays from a /sup 60/Co source and glow curves and thermoluminescence emission spectra recorded. In addition to glow peaks at 385 and 410/sup 0/ K, which are present for undoped BaFCl, peaks occur at 470, 505, 570 and 665/sup 0/ K. The low temperature peaks are attributed to two types of F centre at F(Cl-bar) and F(F-bar) anion vacancies and the additional peaks to the presence of the terbium impurity in the BaFCl lattice. The thermoluminescence spectra show five emission bands. Those at 420, 435, 490 and 545 nm are attributed to transitions between the 4 f excited levels. A 390 nm emission, previously attributed to radiative recombination centres in undoped BaFCl, may in the light of these results be seen to arise from background terbium impurity in the starting material.

  9. Glow discharge optical emission spectroscopy for accurate and well resolved analysis of coatings and thin films

    KAUST Repository

    Wilke, Marcus

    2011-12-01

    In the last years, glow discharge optical emission spectrometry (GDOES) gained more and more acceptance in the analysis of functional coatings. GDOES thereby represents an interesting alternative to common depth profiling techniques like AES and SIMS, based on its unique combination of high erosion rates and erosion depths, sensitivity, analysis of nonconductive layers and easy quantification even for light elements such as C, N, O and H. Starting with the fundamentals of GDOES, a short overview on new developments in instrument design for accurate and well resolved thin film analyses is presented. The article focuses on the analytical capabilities of glow discharge optical emission spectrometry in the analysis of metallic coatings and thin films. Results illustrating the high depth resolution, confirmation of stoichiometry, the detection of light elements in coatings as well as contamination on the surface or interfaces will be demonstrated by measurements of: a multilayer system Cr/Ti on silicon, interface contamination on silicon during deposition of aluminum, Al2O3-nanoparticle containing conversion coatings on zinc for corrosion resistance, Ti3SiC2 MAX-phase coatings by pulsed laser deposition and hydrogen detection in a V/Fe multilayer system. The selected examples illustrate that GDOES can be successfully adopted as an analytical tool in the development of new materials and coatings. A discussion of the results as well as of the limitations of GDOES is presented. © 2011 Elsevier B.V.

  10. Validation and benchmarking of two particle-in-cell codes for a glow discharge

    Science.gov (United States)

    Carlsson, Johan; Khrabrov, Alexander; Kaganovich, Igor; Sommerer, Timothy; Keating, David

    2017-01-01

    The two particle-in-cell codes EDIPIC and LSP are benchmarked and validated for a parallel-plate glow discharge in helium, in which the axial electric field had been carefully measured, primarily to investigate and improve the fidelity of their collision models. The scattering anisotropy of electron-impact ionization, as well as the value of the secondary-electron emission yield, are not well known in this case. The experimental uncertainty for the emission yield corresponds to a factor of two variation in the cathode current. If the emission yield is tuned to make the cathode current computed by each code match the experiment, the computed electric fields are in excellent agreement with each other, and within about 10% of the experimental value. The non-monotonic variation of the width of the cathode fall with the applied voltage seen in the experiment is reproduced by both codes. The electron temperature in the negative glow is within experimental error bars for both codes, but the density of slow trapped electrons is underestimated. A more detailed code comparison done for several synthetic cases of electron-beam injection into helium gas shows that the codes are in excellent agreement for ionization rate, as well as for elastic and excitation collisions with isotropic scattering pattern. The remaining significant discrepancies between the two codes are due to differences in their electron binary-collision models, and for anisotropic scattering due to elastic and excitation collisions.

  11. Numerical modeling of a glow discharge through a supersonic bow shock in air

    Science.gov (United States)

    Rassou, S.; Packan, D.; Elias, P.-Q.; Tholin, F.; Chemartin, L.; Labaune, J.

    2017-03-01

    The interaction between a glow discharge and the bow shock of a Mach 3 air flow around a truncated conical model with a central spike is modeled, and comparison is made with prior experimental results. The KRONOS workflow for plasma modeling in flow fields, which has recently been developed at ONERA, was used for the modeling. Based on the quasi-neutral approximation, it couples hypersonic and reactive flow fields with electron chemistry, including the effect of non-Maxwellian electron energy distribution function. The model used for the discharge involves 12 species and 82 reactions, including ionization, electronic and vibrational excitation, and attachment. The simulations reproduce the main features of the discharge observed experimentally well, in particular, the very recognizable topology of the discharge. It was found from the simulations that behind the bow shock, in the afterglow, the negative ion flow ensures the electrical conduction and the establishment of the glow discharge. The influence of kinetic rates on the voltage-current characteristics is discussed.

  12. Molecular basis for the blue bioluminescence of the Australian glow-worm Arachnocampa richardsae (Diptera: Keroplatidae).

    Science.gov (United States)

    Trowell, Stephen C; Dacres, Helen; Dumancic, Mira M; Leitch, Virginia; Rickards, Rodney W

    2016-09-16

    Bioluminescence is the emission of visible light by living organisms. Here we describe the isolation and characterisation of a cDNA encoding a MW ≈ 59,000 Da luciferase from the Australian glow-worm, Arachnocampa richardsae. The enzyme is a member of the acyl-CoA ligase superfamily and produces blue light on addition of D-luciferin. These results are contrary to earlier reports (Lee, J., Photochem Photobiol 24, 279-285 (1976), Viviani, V. R., Hastings, J. W. & Wilson, T., Photochem Photobiol 75, 22-27 (2002)), which suggested glow-worm luciferase has MW ≈ 36,000 Da and is unreactive with beetle luciferin. There are more than 2000 species of firefly, which all produce emissions from D-luciferin in the green to red regions of the electromagnetic spectrum. Although blue-emitting luciferases are known from marine organisms, they belong to different structural families and use a different substrate. The observation of blue emission from a D-luciferin-using enzyme is therefore unprecedented.

  13. Evidence that Aurora B is implicated in spindle checkpoint signalling independently of error correction

    OpenAIRE

    Santaguida, Stefano; Vernieri, Claudio; Villa, Fabrizio; Ciliberto, Andrea; Musacchio, Andrea

    2011-01-01

    Fidelity of chromosome segregation is ensured by a tension-dependent error correction system that prevents stabilization of incorrect chromosome–microtubule attachments. Unattached or incorrectly attached chromosomes also activate the spindle assembly checkpoint, thus delaying mitotic exit until all chromosomes are bioriented. The Aurora B kinase is widely recognized as a component of error correction. Conversely, its role in the checkpoint is controversial. Here, we report an analysis of the...

  14. Low latitude aurorae as a diagnostic for energetic particle injections and their environment

    Science.gov (United States)

    Thaller, S. A.; Wygant, J. R.; Dai, L.; Dombeck, J. P.; Cattell, C. A.; Mozer, F.; Russell, C. T.; Fennell, J. F.; Claudepierre, S. G.; Mende, S. B.; Frey, H. U.

    2012-12-01

    The region between the inner magnetosphere and the geomagnetic tail/plasma sheet is highly dynamic during geomagnetic storms and hosts many important magnetospheric phenomenon and structures, including particle injections and the outer radiation belt. The energy transport mechanisms in this region during major storms are not yet fully understood, however there is increasing evidence that in the range of invariant latitudes (ILAT) mapping to this dipole-tail boundary region, Alfven waves are an important energy source for the aurora. This range of latitudes, which is roughly 50 to 68 degrees ILAT varying somewhat on the level of magnetospheric disturbance, is low latitude for the aurora. We present a study of intense earthward Alfvenic Poynting flux at the location of, and concomitant with, energetic electron injections during dipolarizations, on field lines mapping to low latitude aurorae. The Poynting flux, when mapped to an ionospheric altitude of 100km, is of sufficient intensity to power the magnetically conjugate auroral luminosities. The preliminary results suggest that wave Poynting flux is an important link between injection events and low latitude aurorae. Thus the observation of the intensification and dynamic behavior of low latitude auroral arcs, i.e. those on field lines that during storms map to the near- tail boundary where particle injections are observed, are an important diagnostic for the occurrence, location, and plasma dynamics associated with energetic particle injections. This has important implications for the Radiation Belt Storm Probes (RBSP) mission. The data gathered by RBSP can be used in conjunction with auroral data from the THEMIS all-sky imaging array in Canada, providing a richer context for the study of radiation belt physics.

  15. Localization of Aurorae with 10 m High Power Radar Technique, using a Rotating Antenna

    OpenAIRE

    Hellgren, Gösta; Meos, Johan

    2011-01-01

    The paper describes the 10 m high power recorder with a rotating antenna that is used since May 1951 for the localization of aurorae at the Radio Wave Propagation Laboratory of the Kiruna Geophysical Observatory (67.8° N, 20.5° E). Continuous observations during the time May 1951–March 1952 have disclosed periods of auroral activity. The preliminary results from these observations indicate that there is a good correlation between the auroral activity, the magnetic activity, and ...

  16. Characterization of the large area plane-symmetric low-pressure DC glow discharge

    Science.gov (United States)

    Avtaeva, S.; Gorokhovsky, V.; Myers, S.; Robertson, S.; Shunko, E.; Zembower, Z.

    2016-10-01

    Electron density and temperature as well as nitrogen dissociation degree in the low-pressure (10-50 mTorr) large area plane-symmetric DC glow discharge in Ar-N2 mixtures are studied by probes and spectral methods. Electron density measured by a hairpin probe is in good agreement with that derived from the intensity ratio of the N2 2nd positive system bands IC , 1 - 3/IC , 0 - 2 and from the intensity ratio of argon ions and atom lines IArII/IArI, while Langmuir probe data provides slightly higher values of electron density. Electron density in the low-pressure DC glow discharge varies with the discharge conditions in the limits of 108-1010 cm- 3. The concept of electron temperature can be used in low-pressure glow discharges with reservations. The intensity ratio of (0-0) vibrational bands of N2 1st negative and 2nd positive systems I391.4/I337.1 exhibits the electron temperature of 1.5-2.5 eV when argon fraction in the mixture is higher than nitrogen fraction and this ratio quickly increases with nitrogen fraction up to 10 eV in pure nitrogen. The electron temperature calculated from Langmuir probe I-V characteristics assuming a Maxwellian EEDF, gives Te 0.3-0.4 eV. In-depth analysis of the EEDF using the second derivative of Langmuir probe I-V characteristics shows that in a low-pressure glow discharge the EEDF is non-Maxwellian. The EEDF has two populations of electrons: the main background non-Maxwellian population of ;cold; electrons with the mean electron energy of 0.3-0.4 eV and the small Maxwellian population of ;hot; electrons with the mean electron energy of 1.0-2.5 eV. Estimations show that with electron temperature lower than 1 eV the rate of the direct electron impact ionization of N2 is low and the main mechanism of N2 ionization becomes most likely Penning and associative ionization. In this case, assumptions of the intensity ratio IN2+ , 391/IN2 , 337 method are violated. In the glow discharge, N2 dissociation degree reaches about 7% with the argon

  17. Inter-domain Cooperation in INCENP Promotes Aurora B Relocation from Centromeres to Microtubules

    Directory of Open Access Journals (Sweden)

    Armando van der Horst

    2015-07-01

    Full Text Available The chromosomal passenger complex is essential for error-free chromosome segregation and proper execution of cytokinesis. To coordinate nuclear division with cytoplasmic division, its enzymatic subunit, Aurora B, relocalizes from centromeres in metaphase to the spindle midzone in anaphase. In budding yeast, this requires dephosphorylation of the microtubule-binding (MTB domain of the INCENP analog Sli15. The mechanistic basis for this relocalization in metazoans is incompletely understood. We demonstrate that the putative coiled-coil domain within INCENP drives midzone localization of Aurora B via a direct, electrostatic interaction with microtubules. Furthermore, we provide evidence that the CPC multimerizes via INCENP’s centromere-targeting domain (CEN box, which increases the MTB affinity of INCENP. In (prometaphase, the MTB affinity of INCENP is outcompeted by the affinity of its CEN box for centromeres, while at anaphase onset—when the histone mark H2AT120 is dephosphorylated—INCENP and Aurora B switch from centromere to microtubule localization.

  18. The color ratio-intensity relation in the Jovian aurora: Hubble observations of auroral components

    Science.gov (United States)

    Gérard, J.-C.; Bonfond, B.; Grodent, D.; Radioti, A.

    2016-10-01

    Spectral observations made with the long slit of the Space Telescope Imaging Spectrograph (STIS) on board Hubble have been used to construct spectral maps of the FUV Jovian aurora. They reveal that the amount of absorption by overlying methane shows significant spatial variations. In this report, we examine the relationship between the auroral brightness of the unabsorbed H2 emission that is proportional to the precipitated electron energy flux, and the ultraviolet color ratio, a proxy of the mean electron energy. We find that it varies significantly between the different components of the aurora and in the polar region. Although no global dependence can be found, we show that the two quantities are better organized in some auroral components such as regions of the main aurororal emission. By contrast, the dependence of the electron characteristic energy in high-latitude and diffuse aurora regions on the auroral energy input is generally more scattered. We conclude that the various auroral components are associated with different electron acceleration processes, some of which are not governed by a simple relation linking the value of a field-aligned acceleration potential with the parallel currents flowing from the ionosphere.

  19. Ground-based Optical Observations of Geophysical Phenomena: Aurora Borealis and Meteors

    Science.gov (United States)

    Samara, Marilia

    2010-10-01

    Advances in low-light level imaging technology have enabled significant improvements in the ground based study of geophysical phenomena. In this talk we focus on two such phenomena that occur in the Earth's ionosphere: aurorae and meteors. Imaging the aurora which is created by the interplay of the Earth's magnetosphere, ionosphere and atmosphere, provides a tool for remote sensing physical processes that are otherwise very difficult to study. By quantifying the intensities, scale sizes and lifetimes of auroral structures, we can gain significant insight into the physics behind the generation of the aurora and the interaction of the magnetosphere with the solar wind. Additionally, the combination of imaging with radars provides complimentary data and therefore more information than either method on its own. Meteor observations are a perfect example of this because the radar can accurately determine only the line-of-sight component of velocity, while imaging provides the direction of motion, the perpendicular velocity and brightness (a proxy for mass), therefore enabling a much more accurate determination of the full velocity vector and mass.

  20. Phosphorylation of CPAP by Aurora-A Maintains Spindle Pole Integrity during Mitosis

    Directory of Open Access Journals (Sweden)

    En-Ju Chou

    2016-03-01

    Full Text Available CPAP is required for centriole elongation during S/G2 phase, but the role of CPAP in mitosis is incompletely understood. Here, we show that CPAP maintains spindle pole integrity through its phosphorylation by Aurora-A during mitosis. Depletion of CPAP induced a prolonged delay in mitosis, pericentriolar material (PCM dispersion, and multiple mitotic abnormalities. Further studies demonstrated that CPAP directly interacts with and is phosphorylated by Aurora-A at serine 467 during mitosis. Interestingly, the dispersal of the PCM was effectively rescued by ectopic expression of wild-type CPAP or a phospho-mimic CPAP-S467D mutant, but not a non-phosphorylated CPAP-S467A mutant. Finally, we found that CPAP-S467D has a low affinity for microtubule binding but a high affinity for PCM proteins. Together, our results support a model wherein CPAP is required for proper mitotic progression, and phosphorylation of CPAP by Aurora-A is essential for maintaining spindle pole integrity.

  1. Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae.

    Science.gov (United States)

    Crary, F J; Clarke, J T; Dougherty, M K; Hanlon, P G; Hansen, K C; Steinberg, J T; Barraclough, B L; Coates, A J; Gérard, J-C; Grodent, D; Kurth, W S; Mitchell, D G; Rymer, A M; Young, D T

    2005-02-17

    The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system, whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere.

  2. Concurrent observations of ultraviolet aurora and energetic electron precipitation with Mars Express

    Science.gov (United States)

    Gérard, J.-C.; Soret, L.; Libert, L.; Lundin, R.; Stiepen, A.; Radioti, A.; Bertaux, J.-L.

    2015-08-01

    The database of the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument between late January 2004 and Mars 2014 has been searched to identify signatures of CO Cameron and CO2+ doublet ultraviolet auroral emissions. This study has almost doubled the number of auroral detections based on SPICAM spectra. Auroral emissions are located in the vicinity of the statistical boundary between open and closed field lines. From a total of 113 nightside orbits with SPICAM pointing to the nadir in the region of residual magnetic field, only nine nightside orbits show confirmed auroral signatures, some with multiple detections along the orbital track, leading to a total of 16 detections. The mean energy of the electron energy spectra measured during concurrent Analyzer of Space Plasma and Energetic Atoms/Electron Spectrometer observations ranges from 150 to 280 eV. The ultraviolet aurora may be displaced poleward or equatorward of the region of enhanced downward electron energy flux by several tens of seconds and shows no proportionality with the electron flux at the spacecraft altitude. The absence of further UV auroral detection in regions located along crustal magnetic field structures where occasional aurora has been observed indicates that the Mars aurora is a time-dependent feature. These results are consistent with the scenario of acceleration of electrons by transient parallel electric field along semiopen magnetic field lines.

  3. A low latitude Auroras catalogue from 1766 to 1797 (Padua, Italy)

    Science.gov (United States)

    De La Guía, M. C.; Dominguez-Castro, F.; Vaquero, J. M.; Bertolin, C.; Gallego, M. C.; Camuffo, D.

    2015-12-01

    It is presented a long term catalogue of aurorae from the observations done by Joseph Toaldo between 1766-1797 at La Specola (the Observatory) in Padua (Italy, 45º24'07.5''N, 11º52'06.8''E). Toaldo was interested in astrometeorology and was the prime mover and the first director of the Astronomic Observatory where he carried out valuable daily observations on both fields. He also taught astronomy and meteorology at the University of Padua. The data was collected from different historical document sources including the original manuscripts made by Toaldo which also contain meteorological readings. A total of 148 aurorae events were recovered from Toaldo's manuscripts. The data reliability was validated using time and season, percentage of the moon illuminated and aurorae directionality. The data shows a secular maximum of the auroral activity around 1780 that occurred at planetary scale. From 1789 onwards there is a sharp decrease of this activity marking the onset of the Dalton Minimum although the solar activity decreases less rapidly. It has also been collected geomagnetic declination measurements taken in Padua between 1725-1799. These geomagnetic observations are consistent with the geomagnetic model gufm1.

  4. Presumable European aurorae in the mid AD 770s were halo displays

    CERN Document Server

    Neuhaeuser, Dagmar

    2015-01-01

    The interpretation of the strong 14-C variation around AD 775 as one (or several) solar super-flare(s) by, e.g., Usoskin et al. (2013) is based on alleged aurora sightings in the mid AD 770s in Europe: A "red cross/crucifix" in AD 773/4/6 from the Anglo-Saxon Chronicle, "inflamed shields" in AD 776 (both listed in the aurora catalogue of Link 1962), and "riders on white horses" in AD 773 (newly proposed as aurora in Usoskin et al. 2013), the two latter from the Royal Frankish Annals. We discuss the reports about these three sightings in detail here. We can show that all three were halo displays: The "red cross" or "crucifix" is formed by the horizontal arc and a vertical pillar of light (either with the Sun during sunset or with the moon after sunset); the "inflamed shields" and the "riders on white horses" were both two mock suns, especially the latter narrated in form of a Christian adaptation of the antique dioscuri motive. While the latter event took place early in AD 774 (dated AD 773 in Usoskin et al. 2...

  5. The Aurora radiation-hydrodynamical simulations of reionization: calibration and first results

    CERN Document Server

    Pawlik, Andreas H; Schaye, Joop; Jeon, Myoungwon; Vecchia, Claudio Dalla

    2016-01-01

    We introduce a new suite of radiation-hydrodynamical simulations of galaxy formation and reionization called Aurora. The Aurora simulations make use of a spatially adaptive radiative transfer technique that lets us accurately capture the small-scale structure in the gas at the resolution of the hydrodynamics, in cosmological volumes. In addition to ionizing radiation, Aurora includes galactic winds driven by star formation and the enrichment of the universe with metals synthesized in the stars. Our reference simulation uses 2x512^3 dark matter and gas particles in a box of size 25 comoving Mpc/h with a force softening scale of at most 0.28 kpc/h. It is accompanied by simulations in larger and smaller boxes and at higher and lower resolution, employing up to 2x1024^3 particles, to investigate numerical convergence. All simulations are calibrated to yield simulated star formation rate (SFR) functions in close agreement with observational constraints at redshift z = 7 and to achieve reionization at z = 8.3, whic...

  6. Phosphorylation of CPAP by Aurora-A Maintains Spindle Pole Integrity during Mitosis.

    Science.gov (United States)

    Chou, En-Ju; Hung, Liang-Yi; Tang, Chieh-Ju C; Hsu, Wen-Bin; Wu, Hsin-Yi; Liao, Pao-Chi; Tang, Tang K

    2016-03-29

    CPAP is required for centriole elongation during S/G2 phase, but the role of CPAP in mitosis is incompletely understood. Here, we show that CPAP maintains spindle pole integrity through its phosphorylation by Aurora-A during mitosis. Depletion of CPAP induced a prolonged delay in mitosis, pericentriolar material (PCM) dispersion, and multiple mitotic abnormalities. Further studies demonstrated that CPAP directly interacts with and is phosphorylated by Aurora-A at serine 467 during mitosis. Interestingly, the dispersal of the PCM was effectively rescued by ectopic expression of wild-type CPAP or a phospho-mimic CPAP-S467D mutant, but not a non-phosphorylated CPAP-S467A mutant. Finally, we found that CPAP-S467D has a low affinity for microtubule binding but a high affinity for PCM proteins. Together, our results support a model wherein CPAP is required for proper mitotic progression, and phosphorylation of CPAP by Aurora-A is essential for maintaining spindle pole integrity.

  7. Strong Solar Control of Infrared Aurora on Jupiter: Correlation Since the Last Solar Maximum

    Science.gov (United States)

    Kostiuk, T.; Livengood, T. A.; Hewagama, T.

    2009-01-01

    Polar aurorae in Jupiter's atmosphere radiate throughout the electromagnetic spectrum from X ray through mid-infrared (mid-IR, 5 - 20 micron wavelength). Voyager IRIS data and ground-based spectroscopic measurements of Jupiter's northern mid-IR aurora, acquired since 1982, reveal a correlation between auroral brightness and solar activity that has not been observed in Jovian aurora at other wavelengths. Over nearly three solar cycles, Jupiter auroral ethane emission brightness and solar 10.7 cm radio flux and sunspot number are positively correlated with high confidence. Ethane line emission intensity varies over tenfold between low and high solar activity periods. Detailed measurements have been made using the GSFC HIPWAC spectrometer at the NASA IRTF since the last solar maximum, following the mid-IR emission through the declining phase toward solar minimum. An even more convincing correlation with solar activity is evident in these data. Current analyses of these results will be described, including planned measurements on polar ethane line emission scheduled through the rise of the next solar maximum beginning in 2009, with a steep gradient to a maximum in 2012. This work is relevant to the Juno mission and to the development of the Europa Jupiter System Mission. Results of observations at the Infrared Telescope Facility (IRTF) operated by the University of Hawaii under Cooperative Agreement no. NCC5-538 with the National Aeronautics and Space Administration, Science Mission Directorate, Planetary Astronomy Program. This work was supported by the NASA Planetary Astronomy Program.

  8. Ortografía y fonética en la Aurora de Chile Orthography and phonetics in the Aurora de Chile

    Directory of Open Access Journals (Sweden)

    Sonia Almau Almau

    2010-01-01

    Full Text Available En este trabajo se analizan los aspectos ortográficos y fonéticos más significativos del periódico “ministerial y político” la Aurora de Chile, dirigido por Camilo Henríquez y redactado por numerosos colaboradores, que apareció semanalmente en 1812 y 1813. Dicho periódico posee un indudable valor documental no solo por ser el primer impreso relevante de Chile, sino por tratarse de un corpus amplio, compuesto por noticias nacionales e internacionales de diversa índole, que refleja perfectamente las preocupaciones ideológicas del movimiento independentista.This paper analyses the most significant orthographic and phonetic aspects of Aurora de Chile, a ministerial and political newspaper published weekly during 1812-1813, which was directed by Camilo Henríquez and written by many contributors. This newspaper has an enormous documentary value, not only because it is the first relevant newspaper in Chile, but also because it constitutes a large corpus, which is made up of national and international news of various kinds, and which clearly reflects the independence movement ideological concerns.

  9. Antitumor Activity of KW-2450 Against Triple-Negative Breast Cancer by Inhibiting Aurora A and B Kinases

    Science.gov (United States)

    Kai, Kazuharu; Kondo, Kimie; Wang, Xiaoping; Xie, Xuemei; Pitner, Mary K.; Reyes, Monica E.; Torres-Adorno, Angie M.; Masuda, Hiroko; Hortobagyi, Gabriel N.; Bartholomeusz, Chandra; Saya, Hideyuki; Tripathy, Debu; Sen, Subrata; Ueno, Naoto T.

    2015-01-01

    Currently, no targeted drug is available for triple-negative breast cancer (TNBC), an aggressive breast cancer that does not express estrogen receptor, progesterone receptor, or HER2. TNBC has high mitotic activity, and since Aurora A and B mitotic kinases drive cell division and are overexpressed in tumors with a high mitotic index, we hypothesized that inhibiting Aurora A and B produces a significant antitumor effect in TNBC. We tested this hypothesis by determining the antitumor effects of KW-2450, a multikinase inhibitor of both Aurora A and B kinases. We observed significant inhibitory activities of KW-2450 on cell viability, apoptosis, colony formation in agar, and mammosphere formation in TNBC cells. The growth of TNBC xenografts was significantly inhibited with KW-2450. In cell cycle analysis, KW-2450 induced tetraploid accumulation followed by apoptosis or surviving octaploid (8N) cells, depending on dose. These phenotypes resembled those of Aurora B knockdown and complete pharmaceutical inhibition of Aurora A. We demonstrated that 8N cells resulting from KW-2450 treatment depended on the activation of mitogen-activated protein kinase kinase (MEK) for their survival. When treated with the MEK inhibitor selumetinib combined with KW-2450, compared with KW-2450 alone, the 8N cell population was significantly reduced and apoptosis was increased. Indeed this combination showed synergistic antitumor effect in SUM149 TNBC xenografts. Collectively, Aurora A and B inhibition had a significant antitumor effect against TNBC, and this antitumor effect was maximized by the combination of selumetinib with Aurora A and B inhibition. PMID:26443806

  10. Antitumor Activity of KW-2450 against Triple-Negative Breast Cancer by Inhibiting Aurora A and B Kinases.

    Science.gov (United States)

    Kai, Kazuharu; Kondo, Kimie; Wang, Xiaoping; Xie, Xuemei; Pitner, Mary K; Reyes, Monica E; Torres-Adorno, Angie M; Masuda, Hiroko; Hortobagyi, Gabriel N; Bartholomeusz, Chandra; Saya, Hideyuki; Tripathy, Debu; Sen, Subrata; Ueno, Naoto T

    2015-12-01

    Currently, no targeted drug is available for triple-negative breast cancer (TNBC), an aggressive breast cancer that does not express estrogen receptor, progesterone receptor, or HER2. TNBC has high mitotic activity, and, because Aurora A and B mitotic kinases drive cell division and are overexpressed in tumors with a high mitotic index, we hypothesized that inhibiting Aurora A and B produces a significant antitumor effect in TNBC. We tested this hypothesis by determining the antitumor effects of KW-2450, a multikinase inhibitor of both Aurora A and B kinases. We observed significant inhibitory activities of KW-2450 on cell viability, apoptosis, colony formation in agar, and mammosphere formation in TNBC cells. The growth of TNBC xenografts was significantly inhibited with KW-2450. In cell-cycle analysis, KW-2450 induced tetraploid accumulation followed by apoptosis or surviving octaploid (8N) cells, depending on dose. These phenotypes resembled those of Aurora B knockdown and complete pharmaceutical inhibition of Aurora A. We demonstrated that 8N cells resulting from KW-2450 treatment depended on the activation of mitogen-activated protein kinase kinase (MEK) for their survival. When treated with the MEK inhibitor selumetinib combined with KW-2450, compared with KW-2450 alone, the 8N cell population was significantly reduced and apoptosis was increased. Indeed, this combination showed synergistic antitumor effect in SUM149 TNBC xenografts. Collectively, Aurora A and B inhibition had a significant antitumor effect against TNBC, and this antitumor effect was maximized by the combination of selumetinib with Aurora A and B inhibition.

  11. Desenvolvimento dos frutos de pêssego 'Aurora' e nectarina 'Sunraycer' no sul de Santa Catarina

    Directory of Open Access Journals (Sweden)

    Emilio Della Bruna

    2011-10-01

    Full Text Available O desenvolvimento do fruto de pessegueiro é resultado da diferenciação e do crescimento das paredes do ovário após a fecundação. A persistência e o crescimento do fruto na planta dependem das relações exatas entre os hormônios auxina, giberelina e citocinina que condicionam o desenvolvimento dos frutos, caracterizado por uma curva dupla sigmoide, com três estádios distintos. O presente trabalho teve por objetivo conhecer o comportamento dos frutos e das sementes do pêssego Aurora e da Nectarina Sunraycer durante todo o seu ciclo de desenvolvimento. O crescimento dos frutos e das sementes durante o ciclo foi determinado semanalmente, coletando-se 30 frutos de dez diferentes plantas em ramos previamente identificados. As sementes foram separadas do fruto para a determinação do peso fresco (PF e do peso seco (PS. O crescimento dos frutos da variedade Sunraycer dá-se de forma contínua e acelerada desde a floração até a maturação, sugerindo um curto período ou a inexistência do Estágio II de crescimento. Para a variedade Aurora, a curva de crescimento é diferenciada nos três estádios (I, II e III. O raleio dos frutos deve ser feito até o início do estádio II, para a variedade Aurora e Sunraycer. As sementes das variedades Aurora e Sunraycer atingem seu tamanho máximo no estágio I de crescimento do fruto. O aumento de peso seco na semente, para a variedade Sunraycer, é praticamente inexistente no estádio III, enquanto para a variedade Aurora ocorre o maior aumento de peso seco que vai até a maturação do fruto.

  12. The effects of moon illumination, moon angle, cloud cover, and sky glow on night vision goggle flight performance

    Science.gov (United States)

    Loro, Stephen Lee

    This study was designed to examine moon illumination, moon angle, cloud cover, sky glow, and Night Vision Goggle (NVG) flight performance to determine possible effects. The research was a causal-comparative design. The sample consisted of 194 Fort Rucker Initial Entry Rotary Wing NVG flight students being observed by 69 NVG Instructor Pilots. The students participated in NVG flight training from September 1992 through January 1993. Data were collected using a questionnaire. Observations were analyzed using a Kruskal-Wallis one-way analysis of variance and a Wilcox matched pairs signed-ranks test for difference. Correlations were analyzed using Pearson's r. The analyses results indicated that performance at high moon illumination levels is superior to zero moon illumination, and in most task maneuvers, superior to >0%--50% moon illumination. No differences were found in performance at moon illumination levels above 50%. Moon angle had no effect on night vision goggle flight performance. Cloud cover and sky glow have selective effects on different maneuvers. For most task maneuvers, cloud cover does not affect performance. Overcast cloud cover had a significant effect on seven of the 14 task maneuvers. Sky glow did not affect eight out of 14 task maneuvers at any level of sky glow.

  13. A study on the behaviour of TLD-100 glow peaks at extreme ambient temperatures in Riyadh, Saudi Arabia.

    Science.gov (United States)

    Al-Haj, Abdalla N; Lagarde, Charlie S

    2006-01-01

    In this study, the temperature-induced variations in the TLD-100 response and the modifications in its glow peaks are investigated in real environmental exposure conditions in Riyadh, Saudi Arabia, where ambient temperatures during summer reach >45 degrees C and with relative humidity of 8814 TLD cardholders were deployed as environmental dosemeters for a period of approximately 1 month for 12 consecutive months. One group was irradiated to 5 mGy 137Cs prior to deployment; another was irradiated to the same dose after deployment, while the last group was left unirradiated. Analysis of glow curves was done using commercially available glow curve deconvolution software (CGCD). Monthly variations in peak 3, 4 and 5 areas relative to the corresponding peak areas of a prompt glow curve are presented. Results of this study show good TL signal compensation between peaks 4 and 5 at all ambient temperatures encountered in this experiment, despite the observed individual variations experienced by each of these peaks. The sum of peak 4 and 5 areas is constant to within approximately 10%, for both pre- and post-irradiated dosemeters, during this 12-month cycle.

  14. Development and fundamental investigation of Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS)

    Energy Technology Data Exchange (ETDEWEB)

    Tarik, Mohamed [ETH Zurich, D-CHAB, Laboratory of inorganic chemistry, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); Lotito, Giovanni [ETH Zurich, D-CHAB, Laboratory of inorganic chemistry, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); TOFWERK AG, Uttigenstr. 22, 3600 Thun (Switzerland); Whitby, James A. [TOFWERK AG, Uttigenstr. 22, 3600 Thun (Switzerland); Mechanics of Materials and Nanostructures Laboratory, Empa - Materials Science and Technology, Feuerwerkerstr. 39, 3602 Thun (Switzerland); Koch, Joachim [ETH Zurich, D-CHAB, Laboratory of inorganic chemistry, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); Fuhrer, Katrin; Gonin, Marc [TOFWERK AG, Uttigenstr. 22, 3600 Thun (Switzerland); Michler, Johann [Mechanics of Materials and Nanostructures Laboratory, Empa - Materials Science and Technology, Feuerwerkerstr. 39, 3602 Thun (Switzerland); Bolli, Jean-Luc [Ecole d' ingenieurs de Geneve, 4 Prairie, 1202 Geneva (Switzerland); Guenther, Detlef [ETH Zurich, D-CHAB, Laboratory of inorganic chemistry, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland)], E-mail: guenther@inorg.chem.ethz.ch

    2009-03-15

    Glow Discharge (GD) spectroscopy is a well known and accepted technique for the bulk and surface composition analysis, while laser ablation (LA) provides analysis with high spatial-resolution analysis in LIBS (laser-induced breakdown spectroscopy) or when coupled to inductively coupled plasma spectrometry (ICP-OES or ICP-MS). This work concerns the construction of a Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS) instrument to study the analytical capabilities resulting from the interaction of a laser-generated sample plume with a pulsed glow discharge. Two ablation configurations were studied in detail. In a first approach, the laser-generated plume was introduced directly into the GD, while the second approach generated the plume inside the GD. The ablated material was introduced at different times with respect to the discharge pulse in order to exploit the efficient ionization in the GD plasma. For both LA-GD configurations, direct ablation into the afterglow of the pulsed glow discharge leads to an ion signal enhancement of up to a factor of 7, as compared to the ablation process alone under the same experimental conditions. The LA-GD enhancement was found to occur exclusively in the GD afterglow, with a maximum ablation S/N occurring in a few hundred microseconds after the termination of the glow discharge. The duration of the enhanced signal is about two milliseconds. Both the laser pulse energy and the position of the ablation plume (with respect to the sampling orifice) were found to affect the amount of mass entering the afterglow region and consequently, the enhancement factor of ionization.

  15. Development and fundamental investigation of Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS)

    Science.gov (United States)

    Tarik, Mohamed; Lotito, Giovanni; Whitby, James A.; Koch, Joachim; Fuhrer, Katrin; Gonin, Marc; Michler, Johann; Bolli, Jean-Luc; Günther, Detlef

    2009-03-01

    Glow Discharge (GD) spectroscopy is a well known and accepted technique for the bulk and surface composition analysis, while laser ablation (LA) provides analysis with high spatial-resolution analysis in LIBS (laser-induced breakdown spectroscopy) or when coupled to inductively coupled plasma spectrometry (ICP-OES or ICP-MS). This work concerns the construction of a Laser Ablation Glow Discharge Time-Of-Flight Mass Spectrometry (LA-GD-TOFMS) instrument to study the analytical capabilities resulting from the interaction of a laser-generated sample plume with a pulsed glow discharge. Two ablation configurations were studied in detail. In a first approach, the laser-generated plume was introduced directly into the GD, while the second approach generated the plume inside the GD. The ablated material was introduced at different times with respect to the discharge pulse in order to exploit the efficient ionization in the GD plasma. For both LA-GD configurations, direct ablation into the afterglow of the pulsed glow discharge leads to an ion signal enhancement of up to a factor of 7, as compared to the ablation process alone under the same experimental conditions. The LA-GD enhancement was found to occur exclusively in the GD afterglow, with a maximum ablation S/N occurring in a few hundred microseconds after the termination of the glow discharge. The duration of the enhanced signal is about two milliseconds. Both the laser pulse energy and the position of the ablation plume (with respect to the sampling orifice) were found to affect the amount of mass entering the afterglow region and consequently, the enhancement factor of ionization.

  16. Stereoscopic determination of all-sky altitude map of aurora using two ground-based Nikon DSLR cameras

    Directory of Open Access Journals (Sweden)

    R. Kataoka

    2013-09-01

    Full Text Available A new stereoscopic measurement technique is developed to obtain an all-sky altitude map of aurora using two ground-based digital single-lens reflex (DSLR cameras. Two identical full-color all-sky cameras were set with an 8 km separation across the Chatanika area in Alaska (Poker Flat Research Range and Aurora Borealis Lodge to find localized emission height with the maximum correlation of the apparent patterns in the localized pixels applying a method of the geographical coordinate transform. It is found that a typical ray structure of discrete aurora shows the broad altitude distribution above 100 km, while a typical patchy structure of pulsating aurora shows the narrow altitude distribution of less than 100 km. Because of its portability and low cost of the DSLR camera systems, the new technique may open a unique opportunity not only for scientists but also for night-sky photographers to complementarily attend the aurora science to potentially form a dense observation network.

  17. Stereoscopic determination of all-sky altitude map of aurora using two ground-based Nikon DSLR cameras

    Science.gov (United States)

    Kataoka, R.; Miyoshi, Y.; Shigematsu, K.; Hampton, D.; Mori, Y.; Kubo, T.; Yamashita, A.; Tanaka, M.; Takahei, T.; Nakai, T.; Miyahara, H.; Shiokawa, K.

    2013-09-01

    A new stereoscopic measurement technique is developed to obtain an all-sky altitude map of aurora using two ground-based digital single-lens reflex (DSLR) cameras. Two identical full-color all-sky cameras were set with an 8 km separation across the Chatanika area in Alaska (Poker Flat Research Range and Aurora Borealis Lodge) to find localized emission height with the maximum correlation of the apparent patterns in the localized pixels applying a method of the geographical coordinate transform. It is found that a typical ray structure of discrete aurora shows the broad altitude distribution above 100 km, while a typical patchy structure of pulsating aurora shows the narrow altitude distribution of less than 100 km. Because of its portability and low cost of the DSLR camera systems, the new technique may open a unique opportunity not only for scientists but also for night-sky photographers to complementarily attend the aurora science to potentially form a dense observation network.

  18. Records of sunspot and aurora during CE 960-1279 in the Chinese chronicle of the Song dynasty

    CERN Document Server

    Hayakawa, Hisashi; Kawamura, Akito D; Isobe, Hiroaki

    2015-01-01

    Records of sunspots and aurora observations in pre-telescopic historical documents can provide useful information about solar activity in the past. This is also true for extreme space weather events, as they may have been recorded as large sunspots observed by the naked eye or as low-latitude auroras. In this paper, we present the results of a comprehensive survey of records of sunspots and auroras in the Songshi, a Chinese formal chronicle spanning the tenth to the thirteenth century. This chronicle contains a record of continuous observations with well-formatted reports conducted as a policy of the government. A brief comparison of the frequency of observations of sunspots and auroras and the observations of radioisotopes as an indicator of the solar activity during corresponding periods is provided. This paper is the first step of our project in which we survey and compile the records of sunspots and aurora in historical documents from various locations and languages, ultimately providing it to the science...

  19. Characteristics of Ozone Production by Using Atmospheric Surface Glow Barrier Discharge

    Directory of Open Access Journals (Sweden)

    Mudtorlep NISOA

    2009-06-01

    Full Text Available Ozone is a strong oxidizer that can kill bacteria and other micro-organisms very effectively. In the recent years, ozone has become very important for sterilization of water used in shrimp farming and treatment of wastewater from food industry. However, ozonisers available in the markets are very expensive and have low energy-efficiency. In this work, a highly-efficient and low-cost system that can produce high-concentrations of ozone gas and dissolved ozone in water has been developed. The system consists of a dried air unit, high-voltage rf power supply, ozoniser tubes and venturi injector. The tubes are designed and configured to convert oxygen gas to ozone gas by atmospheric surface glow barrier discharge.

  20. Degradation of Methyl Orange in Water by Contact Glow Discharge Electrolysis

    Institute of Scientific and Technical Information of China (English)

    GONG Jianying; CAI Weimin

    2007-01-01

    The degradation of methyl orange in a neutral phosphate buffer solution was investigated by means of contact glow discharge electrolysis (CGDE).The methyl oranges were degraded and eventually decomposed into inorganic carbon when CGDE was conducted under the applied DC voltage of 480 V and current of ca.80 mA.As the intermediate products,some phenolic compounds were detected as well as carboxylic acids.Experimental results showed that the oxidation process followed the first-order reaction law.Based on the analysis of the ultraviolet (UV) spectra of the solution and the intermediate products from High Pressure Liquid Chromatography-Mass Spectrum (HPLC-MS),the reaction pathway was proposed.The attack of hydroxyl radicals was considered to be a key step to start the whole oxidation process.

  1. Application of Glow Discharge Aes for Investigation of Metal Ions and Water in Biology and Medicine

    CERN Document Server

    Bregadze, Vasil G; Tsakadze, Ketevan J

    2007-01-01

    AES VHF inductively coupled plasmatron may be applied to wide range of studies. It enables rapid microanalysis of various solutions including biological objects and peripheral blood serum. In addition, it may be used for investigation of water desorption from solid bodies and for determination of energetic metal-macromolecule complexes. Study of hydration energy and hydration number by kinetic curves of water glow discharge atomic spectral analysis of hydrogen (GD EAS analysis of hydrogen) desorption from Na-DNA humidified fibers allowed to reveal that structural and conformational changes in activation energy of hydrated water molecules increases by 0.65kcal/Mole of water. The developed method of analysis of elements in solutions containing high concentrations of organic materials allows systematic study of practically healthy persons and reveals risk factors for several diseases. Microelemental content of blood serum fractions showed that amount of not bounded with ceruloplasmin copper was three times more ...

  2. Aqueous 4-nitrophenol decomposition and hydrogen peroxide formation induced by contact glow discharge electrolysis.

    Science.gov (United States)

    Liu, Yongjun; Wang, Degao; Sun, Bing; Zhu, Xiaomei

    2010-09-15

    Liquid-phase decomposition of 4-nitrophenol (4-NP) and formation of hydrogen peroxide (H(2)O(2)) induced by contact glow discharge electrolysis (CGDE) were investigated. Experimental results showed that the decays of 4-NP and total organic carbon (TOC) obeyed the first-order and pseudo-first-order reaction kinetics, respectively. The major intermediate products were 4-nitrocatechol, hydroquinone, benzoquinone, hydroxyhydroquinone, organic acids and nitrite ion. The final products were carbon dioxide and nitrate ion. The initial formation rate of H(2)O(2) decreased linearly with increasing initial concentration of 4-NP. Addition of iron ions, especially ferric ion, to the solution significantly enhanced the 4-NP removal due to the additional hydroxyl radical formation through Fenton's reaction. A reaction pathway is proposed based on the degradation kinetics and the distribution of intermediate products.

  3. Atmospheric pressure air direct current glow discharge ionization source for ion mobility spectrometry.

    Science.gov (United States)

    Dong, Can; Wang, Weiguo; Li, Haiyang

    2008-05-15

    A new atmospheric pressure air direct current glow discharge (DCGD) ionization source has been developed for ion mobility spectrometry (IMS) to overcome the regularity problems associated with the conventional (63)Ni source and the instability of the negative corona discharge. Its general electrical characteristics were experimentally investigated. By equipping it to IMS, a higher sensitivity was obtained compared to that of a (63)Ni source and corona discharge, and a linear dynamic range from 20 ppb to 20 ppm was obtained for m-xylene. Primary investigations showed that alkanes, such as pentane, which are nondetectable or insensitively detectable with (63)Ni-IMS, can be efficiently detected by DCGD-IMS and the detection limit of 10 ppb can be reached. The preliminary results have shown that the new DCGD ionization source has great potential applications in IMS, such as online monitoring of environment pollutants and halogenated compounds.

  4. Atmospheric-pressure glow plasma synthesis of plasmonic and photoluminescent zinc oxide nanocrystals

    Science.gov (United States)

    Bilik, N.; Greenberg, B. L.; Yang, J.; Aydil, E. S.; Kortshagen, U. R.

    2016-06-01

    In this paper, we present a large-volume (non-micro) atmospheric pressure glow plasma capable of rapid, large-scale zinc oxide nanocrystal synthesis and deposition (up to 400 μg/min), whereas in the majority of the literature, nanoparticles are synthesized using micro-scale or filamentary plasmas. The reactor is an RF dielectric barrier discharge with a non-uniform gap spacing. This design encourages pre-ionization during the plasma breakdown, making the discharge uniform over a large volume. The produced zinc oxide nanocrystals typically have diameters ranging from 4 to 15 nm and exhibit photoluminescence at ≈550 nm and localized surface plasmon resonance at ≈1900 cm-1 due to oxygen vacancies. The particle size can be tuned to a degree by varying the gas temperature and the precursor mixing ratio.

  5. Some properties of a microwave boosted glow discharge source using neon as the operating gas.

    Science.gov (United States)

    Leis, F; Steers, E B

    1996-07-01

    The use of neon as the operating gas for the analysis of aluminium samples with the microwave boosted glow discharge source has been studied. A new type of anode tube allowed the gas to enter the source near the sample surface so that more material was transported into the discharge. Erosion rates have been measured under conditions optimised for high line-to-background ratios and found to be lower than with argon (9 and 21 n/s, respectively). Despite the lower erosion rate the detection limits measured for a number of elements in aluminium are in the range 0.02-1 microg/g and comparable to those obtained with argon as the operating gas.

  6. Self-pulsing in a low-current hollow cathode discharge: From Townsend to glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Yu [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Xie, Kan, E-mail: xiekan@bit.edu.cn [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Zhang, Yu; Ouyang, Jiting [School of Physics, Beijing Institute of Technology, Beijing 100081 (China)

    2016-02-15

    We investigate the self-pulsing phenomenon of a low current cavity discharge in a cylindrical hollow cathode in pure argon. The waveforms of pulsed current and voltage are measured, and the time-averaged and time-resolved images of hollow cathode discharge are recorded by using high-speed intensified charge coupled device camera. The results show that the self-pulsing is a mode transition between low-current stage of Townsend discharge and high-current stage of glow discharge. During the self-pulsing, the current rising time relates to the dissipation of space charges, and the decay time relates to the reconstruction of the virtual anode by the accumulation of positive ions. Whether or not space charges can form and keep the virtual anode is responsible for the discharge mode and hence plays an important role in the self-pulsing phenomenon in low current hollow cathode discharge.

  7. A study of the glow discharge characteristics of contact electrodes at atmospheric pressure in air

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenzheng, E-mail: wzhliu@bjtu.edu.cn; Sun, Guangliang, E-mail: 11121659@bjtu.edu.cn; Li, Chuanhui; Zhang, Rongrong [School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China)

    2014-04-15

    Electric field distributions and discharge properties of rod-rod contact electrodes were studied under the condition of DBD for the steady generation of atmospheric pressure glow discharge plasma (APGD) in air. We found that under the effect of the initial electrons generated in a nanometer-scale gap, the rod-rod cross-contact electrodes yielded APGD plasma in air. Regarding the rod-rod cross-contact electrodes, increasing the working voltage expanded the strong electric field area of the gas gap so that both discharge area and discharge power increased, and the increase in the number of contact points kept the initial discharge voltage unchanged and caused an increase in the plasma discharge area and discharge power. A mesh-like structure of cross-contact electrodes was designed and used to generate more APGD plasma, suggesting high applicability.

  8. Surface alloying of Cu with Ti by double glow discharge process

    Institute of Scientific and Technical Information of China (English)

    袁庆龙; 池成忠; 苏永安; 徐重; 唐宾

    2004-01-01

    The surface of pure copper alloyed with Ti using double glow discharge process was investigated. The morphology, structure and forming mechanism of the Cu-Ti alloying layer were analyzed. The microhardness and wear resistance of the Cu-Ti alloying layer were measured, and compared with those of pure copper. The results indicate that the surface of copper activated by Ar and Ti ions bombardment is favorable to absorption and diffusion of Ti element. In current experimental temperature, as the Ti content increases, the liquid phase occurs between the deposited layer and diffused layer, which makes the Ti ions and atoms easy to dissolve and the thickness of Cu-Ti alloying layer increase rapidly. After cooling, the structure of the alloying layer is composed of CuTi, Cu4 Ti and Cu(Ti) solid solution. The solid solution strengthening and precipitation strengthening effects of Ti result in high surface hardness and wear resistance.

  9. Modelling cathode spots in glow discharges in the cathode boundary layer geometry

    CERN Document Server

    Almeida, P G C; Bieniek, M S

    2015-01-01

    Self-organized patterns of cathode spots in glow discharges are computed in the cathode boundary layer geometry, which is the one employed in most of the experiments reported in the literature. The model comprises conservation and transport equations of electrons and a single ion species, written in the drift-diffusion and local-field approximations, and Poisson's equation. Multiple solutions existing for the same value of the discharge current and describing modes with different configurations of cathode spots are computed by means of a stationary solver. The computed solutions are compared to their counterparts for plane-parallel electrodes, and experiments. All of the computed spot patterns have been observed in the experiment.

  10. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    Science.gov (United States)

    Sun, Wen-Ting; Li, Guo; Li, He-Ping; Bao, Cheng-Yu; Wang, Hua-Bo; Zeng, Shi; Gao, Xing; Luo, Hui-Ying

    2007-06-01

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

  11. Double Glow Plasma Surface Alloying Process Modeling Using Artificial Neural Networks

    Institute of Scientific and Technical Information of China (English)

    Jiang XU; Xishan XIE; Zhong XU

    2003-01-01

    A model is developed for predicting the correlation between processing parameters and the technical target of double glowby applying artificial neural network (ANN). The input parameters of the neural network (NN) are source voltage, workpiecevoltage, working pressure and distance between source electrode and workpiece. The output of the NN model is three importanttechnical targets, namely the gross element content, the thickness of surface alloying layer and the absorption rate (the ratioof the mass loss of source materials to the increasing mass of workpiece) in the processing of double glow plasma surfacealloying. The processing parameters and technical target are then used as a training set for an artificial neural network. Themodel is based on multiplayer feedforward neural network. A very good performance of the neural network is achieved and thecalculated results are in good agreement with the experimental ones.

  12. Photoelectronic properties of hydrogenated amorphous silicon films deposited by R. F sputtering and glow discharge methods

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Rahman, M.; Madkour, H. (Faculty of Science, Aswan (Egypt)); Hassan, H.H.; El-Desouki, S. (Cairo Univ., Giza (Egypt))

    1989-09-01

    Hydrogenated amorphous silicon films a-Si:H were deposited by both R.F. sputtering in a planar magnetron configuration and glow discharge methods on Corning glass substrates at different substrate temperatures. The dc and ac photoconductivities of the deposited films were extensively studied as a function of temperature, photon energy and photo-excitation intensity. The results showed that, the dark and photoconductivities have different dependency regions on temperature with different activation energies in the range of 0.08-0.20 eV. It has been also found that the photoconductivity is influenced by the method of deposition and the deposition parameters, indicating that the density of gap states is sensitive to the deposition conditions. The photoconductivity ({sigma}{sub ph}) has a power dependence on the illumination intensity (I) of the form {sigma}{sub ph} {alpha} I {sup {nu}}, where {nu} is a constant and was found also to be increase with temperature.

  13. Inactivation of Escherichia Coli Using Remote Low Temperature Glow Discharge Plasma

    Institute of Scientific and Technical Information of China (English)

    HU Miao; CHEN Jierong; CHEN Chua

    2008-01-01

    Low-temperature plasma is distinguished as a developing approach for sterilization which can deal with and overcome those problems such as thermal sensitivity and destruction by heat,formation of toxic by-products,higher costs and inefficiency in performances,caused by conventional methods.In this study,an experimental investigation was undertaken to characterize the effects of the operational parameters,such as treating time,discharge power and gas flow rate,of remote glow discharge air plasma.The results show that the inactivation of Escherichia coli can reach above 99.99% in less than 60 seconds and the optimal operational conditions for treating time,discharge power and gas flow rate were:40 s,80 W and 60 cm3/min,respectively.The contribution of UV radiation during plasma germ deactivation is very limited.

  14. Multi-element and isotopic analyses of iron meteorites using a glow discharge mass spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Shimamura, Tadashi (Kitasato Univ., Sagamihara (Japan). School of Hygienic Sciences); Takahashi, Takako (Marubun Corp., Kotoku, Tokyo (Japan). Analytical Research Lab.); Honda, Masatake; Nagai, Hisao (Nihon Univ., Tokyo (Japan). Coll. of Humanities and Sciences)

    1993-04-01

    Multi-element and isotopic analyses were performed of eight iron meteorites using a glow discharge mass spectrometer. Virtually all the elements can be determined. Major components (Fe, Co and Ni) through to ultra-trace constituents at the sub ng g[sup -1] level (Sc etc.) are measured directly with minimum chemical treatment within the same analytical cycle. Extremely high relative concentrations of Ni, Cu, Pd, In, Sn, Sb, Te, Pb and Bi were found in the meteorite Yamato 791694; the concentration of C was also very high. The isotopic composition of Pb in this meteorite was close to primordial. Low concentrations of C, N and O were found in the meteorite Gibeon. Very low S and Zn and high Cr and V were found in a third meteorite, Chinga. An excess of [sup 53]Cr was observed in Yamato 75031, which was consistent with the cosmic ray production level expected from the concentration of [sup 45]Sc. (Author).

  15. Glow discharge optical emission spectroscopy: a complementary technique to analyze thin electrodeposited polyaniline films

    Energy Technology Data Exchange (ETDEWEB)

    Moutarlier, V. [Institut UTINAM, CNRS-UMR 6213, Université de Franche-Comté, 16 route de Gray, 25030 Besançon (France); Lakard, S., E-mail: sophie.lakard@univ-fcomte.fr [Institut UTINAM, CNRS-UMR 6213, Université de Franche-Comté, 16 route de Gray, 25030 Besançon (France); Patois, T. [Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Croix du Sud, 1/4, 1348 Louvain-la-Neuve (Belgium); Lakard, B. [Institut UTINAM, CNRS-UMR 6213, Université de Franche-Comté, 16 route de Gray, 25030 Besançon (France)

    2014-01-01

    Glow Discharge Optical Emission Spectroscopy (GDOES) has been developed to perform depth profiles of thick metallic films, in tens of microns range. GDOES spectroscopy can also be used to analyze thin organic polymer films since this technique has a great potential thanks to its high depth resolution, multi-element capability, sensitivity, and adaptability to solids or films and to conducting or non-conducting samples. In particular thin electrodeposited conducting polymer films remain an unexplored field of investigation for GDOES technique. However GDOES was used in this work to analyze electrodeposited polyaniline films, in addition to other techniques such as profilometry, electron microscopy and X-ray diffraction (XRD). More precisely polyaniline thin films were electrodeposited from HCl solutions and the presence of an anilinium chloride excess at the top surface of the polymer film was demonstrated using GDOES and XRD. Rinsing of these films with water led to the removal of this excess and to the partial dedoping of the polymer film due to the porous structure of polymer films. Polyaniline thin films were also electrodeposited from H{sub 2}SO{sub 4} solutions and an anilinium hydrogen sulfate was similarly observed at the top surface of the polymer. This excess was removed by rinsing, contrary to hydrogen sulfate anions incorporated into the polymer film during the electrochemical polymerization that were not completely expulsed from the polyaniline films as proved using GDOES. - Highlights: • Polyaniline films were electrodeposited from HCl and H{sub 2}SO{sub 4} solutions • Polymer films were analyzed by Glow Discharge Optical Emission Spectroscopy (GDOES) • The incorporation of anions in the films was proved using GDOES depth profiles • The crystalline structure of polyaniline films was modified by water rinsing.

  16. Low-pressure glow discharge in a Xenon/Chlorine mixture

    Science.gov (United States)

    Shuaibov, A. K.; Shimon, L. L.; Shevera, I. V.; Dashchenko, A. I.

    2002-12-01

    The spatial, electrical, and optical characteristics of a transverse glow discharge and a volume discharge with a spherical anode and plane cathode in low-pressure Xe/Cl2 mixtures are studied. It is shown that the transverse glow discharge in mixtures with a low chlorine content occupies most of the interelectrode gap and exists in the form of strata. As the total pressure ( P≥300 Pa) and the partial chlorine pressure ( P(Cl2)≥80 Pa) increase, a solitary plasma domain with a volume of 1-2 cm3 forms in the discharge gap. It acts as a selective source of UV radiation in the XeCl(D-X) 236-nm, Cl2 (D'-A') 257-nm, and XeCl(B-X) 308-nm bands. In certain Xe/Cl2 mixtures, plasma self-oscillations in the frequency range 1-100 kHz are observed. The current of a low-pressure volume discharge with a spherical anode and plane cathode and the emission from it have both a dc and an ac component. The pressure and composition of the working mixture, as well as the average current of the volume discharge are optimized to attain the maximum emission intensity of the XeCl(D,B-X) bands. Low-pressure volume discharges in xenon/chlorine mixtures can be used as active media in low-pressure large-aperture planar or cylindrical excimer-halogen lamps emitting modulated or repetitive pulsed UV radiation.

  17. The Key Factor for Uniform and Patterned Glow Dielectric Barrier Discharge

    Institute of Scientific and Technical Information of China (English)

    OUYANG Ji-Ting; DUAN Xiao-Xi; XU Shao-Wei; HE Feng

    2012-01-01

    We present the results from 2D fluid modeling of the key roles controlling the glow dielectric barrier discharge (DBD) structure. A uniform DBD can be sustained at lower frequency when the space charge reaches uniformity due to plasma decay, while the patterned structure appears above a critical frequency when the space charge is nonuniform. The patterns start from the electrode edge where the electric field is significantly distorted, characterized by the patterned seed electrons that always form ahead of the surface charges. The formation of the patterned DBD structure is associated with the lateral inhibition of the local increase of space charges. The distribution of the volume seed electrons plays a key role in the DBD structure while the distribution of surface charge is a result of the formed structure.%We present the results from 2D fluid modeling of the key roles controlling the glow dielectric barrier discharge (DBD) structure.A uniform DBD can be sustained at lower frequency when the space charge reaches uniformity due to plasma decay,while the patterned structure appears above a critical frequency when the space charge is nonuniform.The patterns start from the electrode edge where the electric field is significantly distorted,characterized by the patterned seed electrons that always form ahead of the surface charges.The formation of the patterned DBD structure is associated with the lateral inhibition of the local increase of space charges.The distribution of the volume seed electrons plays a key role in the DBD structure while the distribution of surface charge is a result of the formed structure.

  18. The aurora kinase inhibitor VX-680 shows anti-cancer effects in primary metastatic cells and the SW13 cell line.

    Science.gov (United States)

    Pezzani, Raffaele; Rubin, Beatrice; Bertazza, Loris; Redaelli, Marco; Barollo, Susi; Monticelli, Halenya; Baldini, Enke; Mian, Caterina; Mucignat, Carla; Scaroni, Carla; Mantero, Franco; Ulisse, Salvatore; Iacobone, Maurizio; Boscaro, Marco

    2016-10-01

    New therapeutic targets are needed to fight cancer. Aurora kinases (AK) were recently identified as vital key regulators of cell mitosis and have consequently been investigated as therapeutic targets in preclinical and clinical studies. Aurora kinase inhibitors (AKI) have been studied in many cancer types, but their potential capacity to limit or delay metastases has rarely been considered, and never in adrenal tissue. Given the lack of an effective pharmacological therapy for adrenal metastasis and adrenocortical carcinoma, we assessed AKI (VX-680, SNS314, ZM447439) in 2 cell lines (H295R and SW13 cells), 3 cell cultures of primary adrenocortical metastases (from lung cancer), and 4 primary adrenocortical tumor cell cultures. We also tested reversan, which is a P-gp inhibitor (a fundamental efflux pump that can extrude drugs), and we measured AK expression levels in 66 adrenocortical tumor tissue samples. Biomolecular and cellular tests were performed (such as MTT, thymidine assay, Wright's staining, cell cycle and apoptosis analysis, Western blot, qRT-PCR, and mutation analysis). Our results are the first to document AK overexpression in adrenocortical carcinoma as well as in H295R and SW13 cell lines, thus proving the efficacy of AKI against adrenal metastases and in the SW13 cancer cell model. We also demonstrated that reversan and AKI Vx-680 are useless in the H295R cell model, and therefore should not be considered as potential treatments for ACC. Serine/threonine AK inhibition, essentially with VX-680, could be a promising, specific therapeutic tool for eradicating metastases in adrenocortical tissue.

  19. R. B. Cunninghame Graham’s “Aurora La Cujiñi” (1898 : An Exploration / Aurora La Cujiñi” (1898 de R. B. Cunninghame Graham - Una indagación

    Directory of Open Access Journals (Sweden)

    John C. Mc Intyre

    2011-06-01

    Full Text Available Abstract: In Aurora La Cujiñi-A realistic sketch in Seville, published by the Scottish writer R. B. Cunninghame Graham in 1898, the frontispiece showed the sepia image of a female flamenco dancer. What might ‘La Cujiñi’ mean? Charles Davillier and Gustave Doré in 1862-63 note the existence of a Sevillan dancer with this name. In 2011 the present writer was gifted an old lithograph, in colour, published in Seville ‘c. 1850’ and entitled ‘Aurora La Cujiñí’ - with ñ and í. The two images are supplied. ‘Aurora La Cujiñi’ really existed. Graham’s sketch has five phases: Seville; the bullfight; the crowd’s return to town; a low-quality flamenco show; and the highly stirring performance by an initially anonymous female dancer - the dead Aurora brought back to life. Graham emphasises the Seville blend of blood and sensuality in a realist style also capable of mockery and criticism. Graham’s writing includes a good variety of well-controlled Spanish vocabulary, his empathy with horses and a deep nostalgia for times past. W. H. Hudson, writer and friend of Graham, in 1894 recommended that Graham should read the Argentine sketches published by Alfred Ébélot in 1890. In Aurora La Cujiñi Graham in 1898 is beginning to show mastery of the literary sketch. Question: Might Lorca have read Aurora La Cujiñi before drafting “Teoría y juego del duende”? Resumen: En Aurora La Cujiñi-A realistic sketch in Seville (1898 del escritor escocés R. B. Cunninghame Graham, el frontispicio llevaba la imagen en sepia de una bailadora de flamenco. ¿Qué podría significar ‘La Cujiñi’? Charles Davillier y Gustave Doré en 1862-1863 apuntan la existencia de una bailaora sevillana con este nombre. En 2011 al que esto escribe le regalaron una litografía antigua, en color, publicada en Sevilla ‘hacia 1850’ e intitulada ‘Aurora la Cujiñí’ - con ñ y con í. Se incluyen las dos imágenes. ‘Aurora La Cujiñi’ realmente

  20. The inhibitory effect of Sulindac on human pancreatic cancer cells' proliferation by targeting survivin/ Aurora B pathway%舒林酸经survivin/Aurora B途径对人胰腺癌细胞分裂的阻断效应

    Institute of Scientific and Technical Information of China (English)

    范学科; 廖宇圣; 张翠芳; 陈芬; 高慧涛; 覃华; 李德民; 赵秋

    2008-01-01

    Objective To observe the expression of survivin and Aurora B in human pancreatic cancer BXPC3 cells after the treatment of sulindac and to explore the potential mechanism. Methods MTr assay was used to determine the effect of sulindac on the proliferation of the BXPC3 cells. RT-PCR was used to detect the expression of mRNA level of survivin and Aurora B, western blot was used to detect protein expression of survivin and Aurora B Thr-232. Cell cycle and apoptosis were detected by flow eytometry (FCM). Results The BXPC3 cells were inhibited by sulindac in a dose and time-dependent manner; the expression of mRNA of survivin and Aurora B were both significantly decreased from 1.5644 and 0.6554 to 0. 4372 and 0.1132 (P< 0.01), the expression of survivin protein and the phosphorylation of Aurora B Thr-232 were also decreased from 1.2735 and 0.4680 to 0.2126 and 0.2546 (P<0.01); the proportion of cells in the G0/G1 phase was increased from (56.65±1.93)% to (70.58±3.21)% (P<0.01). Conclusions Sulindac had inhibitory effects on the growth of BXPC3 cells, the possible mechanism was via decreasing the expression of survivin which depressed the activity of Aurora B, then the CPC was influenced. The most of the cells were blocked in the G0/G1 phase, and the cells' mitosis was inhibited.%目的 观察舒林酸处理胰腺癌细胞BxPC3后对survivin、Aurora B表达及细胞周期和增殖的影响,探讨舒林酸的作用机制.方法 应用MTT法检测舒林酸对BxPC3细胞的增殖抑制作用,RT-PCR法检测survivin mRNA、Aurora B mRNA的表达,Western blot法检测survivin蛋白表达及Aurora BThr-232磷酸化水平,流式细胞仪检测细胞周期变化.结果 舒林酸呈时间和剂量依赖性抑制BxPC3细胞增殖.经500μmoL/L舒林酸作用细胞48 h后,survivin mRNA和Aurora B mRNA表达量分别从1.56和0.66下降到0.44和0.11(P<0.01);survivin蛋白表达从1.27下降到0.21(P<0.01),Aurora BThr-232磷酸化水平从0.47下降到0.25(P<0.01);G0/G1

  1. Conservação de pêssego 'Aurora-1' armazenados sob refrigeração Keeping quality of peaches 'Aurora-1' stored under refrigeration

    Directory of Open Access Journals (Sweden)

    Luis Carlos Cunha Junior

    2010-06-01

    Full Text Available Avaliou-se o comportamento pós-colheita de pêssegos da cv. Aurora-1 armazenados sob refrigeração. Os frutos foram colhidos em dois estádios de maturação, verde maduro (de vez e maduro. Os lotes foram armazenados em três temperaturas (2°C; 6°C e 12°C, por 35 dias, e avaliados a cada sete dias: quanto à coloração da casca, perda acumulada de massa fresca (PMF, firmeza (FIR, aparência, teores de acidez titulável (AT, sólidos solúveis (SS, açúcares solúveis (AS e redutores (AR, pectina solúvel (PS e total (PT, além da porcentagem de solubilização de pectinas (SOL. A menor temperatura de armazenamento elevou o tempo de prateleira dos pêssegos, e os frutos "de vez" apresentaram melhor aparência. A PMF demonstrou um gradiente em função do aumento da temperatura, e os frutos "de vez" apresentaram menor perda ao final do armazenamento sob todas as temperaturas, quando comparados aos maduros. A coloração da casca dos frutos "de vez", a 2°C, teve pouca alteração, conferindo-lhes mudança de coloração de verde-amarelada para amarelo-clara; enquanto nas temperaturas de 6°C e 12°C esse gradiente foi mais intenso. O mesmo efeito foi verificado nos pêssegos maduros. A FIR sofreu efeito da temperatura, pois temperaturas menores sofreram redução mais lenta e AT dos pêssegos maduros foi superior aos "de vez". Não houve influência dos tratamentos nos teores de SS, AS e AR. Os pêssegos 'Aurora-1' não demonstraram sensibilidade ao frio, e os "de vez", armazenados a 2°C, tiveram vida útil de 35 dias.This work aimed to evaluate the postharvest of peaches cv. Aurora-1 stored under refrigeration. The fruit were harvested in two stages ("mature green" and ripe. The lots were stored at three temperatures (2°C, 6°C, and 12°C, for 35 days and evaluated every seven days for skin color, loss of fresh mass (PMF, firmness (FIR, appearance, titratable acidity (TA, soluble solids (SS, soluble (AS and reducing (AR sugars, soluble

  2. Aurora kinase B is important for antiestrogen resistant cell growth and a potential biomarker for tamoxifen resistant breast cancer

    DEFF Research Database (Denmark)

    Larsen, Sarah L; Yde, Christina W; Laenkholm, Anne-Vibeke

    2015-01-01

    treatment targets. METHODS: Antiestrogen sensitive and resistant T47D breast cancer cell lines were used as model systems. Parental and fulvestrant resistant cell lines were subjected to a kinase inhibitor library. Kinase inhibitors preferentially targeting growth of fulvestrant resistant cells were...... for endocrine resistance, immunohistochemistry was performed on archival primary tumor tissue from breast cancer patients who have received adjuvant endocrine treatment with tamoxifen. RESULTS: The selective Aurora kinase B inhibitor barasertib was identified to preferentially inhibit growth of fulvestrant...... resistant T47D breast cancer cell lines. Compared with parental cells, phosphorylation of Aurora kinase B was higher in the fulvestrant resistant T47D cells. Barasertib induced degradation of Aurora kinase B, caused mitotic errors, and induced apoptotic cell death as measured by accumulation of SubG1 cells...

  3. AURORA BOREALIS - Icebreaker, Drilling Platform and Multi-Purpose Research Vessel

    Science.gov (United States)

    Kunz-Pirrung, M.; Biebow, N.; Lembke-Jene, L.; Thiede, J.; Egerton, P.

    2007-12-01

    In spite of the critical role of the Arctic Ocean in climate evolution, it is the only sub-basin of the world's oceans that has essentially not been sampled by the drill ships of the Deep-Sea Drilling Project (DSDP) or the Ocean Drilling Program (ODP), and its long-term environmental history and tectonic structure is therefore poorly known. Exceptions are the ODP Leg 151 and the more recent very successful ACEX-expedition of the Integrated Ocean Drilling Program (IODP). This lack of data represents one of the largest gaps of information in modern Earth Science. Therefore, the new research icebreaker AURORA BOREALIS will be equipped with drilling facilities to fulfil the needs of the IODP for a -Mission-Specific Platform- to drill in deep, permanently ice-covered ocean basins. This icebreaker must be also powerful enough to maintain station against the drifting sea-ice cover and will have to be equipped with a dynamic positioning system. This new icebreaker would be conceived as an optimized science platform from the keel up and will allow conducting long, international and interdisciplinary expeditions into the central Arctic Ocean during all seasons of the year. In a long-term perspective the AURORA BOREALIS will also be used to address Antarctic research targets, both in its mode as a regular research vessel as well as a polar drill ship. The construction of AURORA BOREALIS requires several new technical implementations, such as advanced dynamic positioning and deep-sea drilling under a closed sea-ice cover and two moon pools (7 x 7 m), and will provide an extended technical potential and knowledge for marine technology. The scientific and technical details will be presented.

  4. The Aurora radiation-hydrodynamical simulations of reionization: calibration and first results

    Science.gov (United States)

    Pawlik, Andreas H.; Rahmati, Alireza; Schaye, Joop; Jeon, Myoungwon; Dalla Vecchia, Claudio

    2017-04-01

    We introduce a new suite of radiation-hydrodynamical simulations of galaxy formation and reionization called Aurora. The Aurora simulations make use of a spatially adaptive radiative transfer technique that lets us accurately capture the small-scale structure in the gas at the resolution of the hydrodynamics, in cosmological volumes. In addition to ionizing radiation, Aurora includes galactic winds driven by star formation and the enrichment of the universe with metals synthesized in the stars. Our reference simulation uses 2 × 5123 dark matter and gas particles in a box of size 25 h-1 comoving Mpc with a force softening scale of at most 0.28 h-1 kpc. It is accompanied by simulations in larger and smaller boxes and at higher and lower resolution, employing up to 2 × 10243 particles, to investigate numerical convergence. All simulations are calibrated to yield simulated star formation rate functions in close agreement with observational constraints at redshift z = 7 and to achieve reionization at z ≈ 8.3, which is consistent with the observed optical depth to reionization. We focus on the design and calibration of the simulations and present some first results. The median stellar metallicities of low-mass galaxies at z = 6 are consistent with the metallicities of dwarf galaxies in the Local Group, which are believed to have formed most of their stars at high redshifts. After reionization, the mean photoionization rate decreases systematically with increasing resolution. This coincides with a systematic increase in the abundance of neutral hydrogen absorbers in the intergalactic medium.

  5. Floristic Inventory of The Proposed Site for Tarsier Tourism Center in Villa Aurora, Bilar, Bohol, Philippines

    Directory of Open Access Journals (Sweden)

    Tomas D Reyes Jr

    2016-03-01

    Keywords: floristic inventory, Philippine tarsier, Bohol, primate conservation, tourism.   Inventarisasi flora dari Situs Usulan untuk Sentra Wisata Tarsier di Villa Aurora, Bilar, Bohol, Filipina Abstract Penelitian ini ditujukan untuk melakukan penilaian komposisi vegetasi dari Usulan Lokasi Pusat Wisata Tarsius (ULPWT di Villa Aurora, Bilar, Bohol dan melakukan analisis perbandingan antara Tarsier Sanctuary (TS yang ada di Canapnapan, Corella, Bohol. Dasar perbandingan yang digunakan yaitu dengan menghitung nilai penting, kekayaan spesies, dominansi spesies, dan prosentase distribusi dari tumbuhan berdasarkan kelas diameter yang telah ditentukan. Hasil penelitian menunjukkan bahwa kedua tempat memiliki kekayaan spesies dan nilai evenness/ kemerataan yang sangat tinggi. Spesies tumbuhan yang umum ditemukan di overstorey dan understorey di kedua area adalah katagpo (Psychotria sp., sagimsim (Syzygium brevistylum [C. B. Rob]Merr., dan bagauak (Clerodendrum minahassae Teijsm. & Binn.. Selain itu, sagimsim (Syzygium brevistylum [C.B.Rob.] Merr., selaginella (Selaginella cuppresina Lin., dan lunas (Lunasia amara Blanco juga umum ditemukan di lantai hutan di kedua tempat. Prosentase distribusi dari tumbuhan berdasarkan kelas diameter yang telah ditentukan menunjukkan bahwa ULPWT memiliki 87.55% dari keseluruhan tumbuhan yang tercatat dengan ukuran diameter 20 cm. Prosentase distribusi dari pohon pada kisaran ini (khususnya pada diameter >20 cm menunjukkan adanya kehadiran pohon berukuran medium dan besar. Diameter terbesar yang terukur di ULPWT adalah 70 cm sementara di TS hanya sebesar 22 cm. Lokasi seluas 10 ha di Villa Aurora, Bilar, sesuai untuk digunakan sebagai Pusat Wisata Tarsius. Apabila akan didirikan, maka kandang yang dibangun diharapkan mirip dengan yang telah dibangun di Canapnapan, Corella, Bohol, Pilipina, agar mencegah pemangsaan oleh satwa yang lepas.

  6. Polo kinase regulates the localization and activity of the chromosomal passenger complex in meiosis and mitosis in Drosophila melanogaster.

    Science.gov (United States)

    Carmena, Mar; Lombardia, Miguel Ortiz; Ogawa, Hiromi; Earnshaw, William C

    2014-11-01

    Cell cycle progression is regulated by members of the cyclin-dependent kinase (CDK), Polo and Aurora families of protein kinases. The levels of expression and localization of the key regulatory kinases are themselves subject to very tight control. There is increasing evidence that crosstalk between the mitotic kinases provides for an additional level of regulation. We have previously shown that Aurora B activates Polo kinase at the centromere in mitosis, and that the interaction between Polo and the chromosomal passenger complex (CPC) component INCENP is essential in this activation. In this report, we show that Polo kinase is required for the correct localization and activity of the CPC in meiosis and mitosis. Study of the phenotype of different polo allele combinations compared to the effect of chemical inhibition revealed significant differences in the localization and activity of the CPC in diploid tissues. Our results shed new light on the mechanisms that control the activity of Aurora B in meiosis and mitosis.

  7. AURORA BOREALIS - Development of a New Research Icebreaker with Drilling Capability

    Science.gov (United States)

    Thiede, J.; Biebow, N.; Egerton, P.; Kunz-Pirrung, M.; Lembke-Jene, L.

    2007-12-01

    Polar research both on land and in the sea cannot achieve the needed progress without novel and state of the art technologies and infrastructure. In addition, we have the obligation to equip the upcoming young and courageous generation of polar researchers with the most modern and safest research platforms the 21st century can provide. This effort will require major investments, both in terms of generating new tools, as well as maintaining and renovating existing infrastructure. There are many different novel tools under development for polar research, we will concentrate on the presently largest one, the planning for a new type of research icebreaker, the AURORA BOREALIS with an all-season capability of operations in permanently ice-covered waters and with the possibility to carry out deep-sea drilling in ice-covered deep-sea basins. AURORA BOREALIS will be the most advanced Polar Research Vessel in the world with a multi-functional role of drilling in deep ocean basins and supporting climate and environmental research and decision support for stakeholder governments for the next 35 to 40 years. The vessel is planned as a large research icebreaker with 44,000 tons displacement and a length of up to 196 m, with about 50 Megawatt propulsion power. Advanced technological features will include azimuth propulsion systems, extensive instrumental and airborne ice- management support, and the routine operation of Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUVs) from two moon-pools. An unique feature of this icebreaker will be the drilling rig that will enable sampling of the ocean floor and sub-sea down to 5000 m water depth and 1000 m penetration at the most inhospitable places on earth. The possibility to flexibly equip the ship with laboratory and supply containers, and the variable arrangement of other modular infrastructure (in particular, winches, cranes, etc.), free deck- space, and separate protected deck areas, will allow the planned

  8. Indole Alkaloids from the Sea Anemone Heteractis aurora and Homarine from Octopus cyanea.

    Science.gov (United States)

    Shaker, Kamel H; Göhl, Matthias; Müller, Tobias; Seifert, Karlheinz

    2015-11-01

    The two new indole alkaloids 2-amino-1,5-dihydro-5-(1H-indol-3-ylmethyl)-4H-imidazol-4-one (1), 2-amino-5-[(6-bromo-1H-indol-3-yl)methyl]-3,5-dihydro-3-methyl-4H-imidazol-4-one (2), and auramine (3) have been isolated from the sea anemone Heteractis aurora. Both indole alkaloids were synthesized for the confirmation of the structures. Homarine (4), along with uracil (5), hypoxanthine (6), and inosine (7) have been obtained from Octopus cyanea.

  9. Inference of atomic oxygen concentration from remote sensing of optical aurora

    Science.gov (United States)

    Shepherd, M. G.; McConnell, J. C.; Tobiska, W. K.; Gladstone, G. R.; Chakrabarti, S.; Schmidtke, G.

    1995-09-01

    A remote sensing method has been developed for the determination of the [O]/[O-MSIS] ratio in aurora, using ratios of the O I (557.7 nm) and N+2 (391.4 nm) emissions. It is shown that the method can be used for the analysis of measurements integrated along the line of sight, provided data only above the emission rate peak are used. The method is applied to the case of horizontal viewing from a vertically oriented rocket so that a large volume of space was sampled around the rocket. The method can potentially be applied to satellite limb images, provided some independent information about the location of the aurora is available, as it was for the rocket observations. Photometric measurements of the N+2 (391.4 nm) and O I (557.7 nm) emissions obtained during the Energy Budget Campaign 1980 on flight E-2 with the instrument EF11 and its reflight in 1981 were used in the analysis presented. During the first flight the rocket horizontally viewed two distinct aurorae, a nearby diffuse patch, and a more distant pulsating aurora. Results obtained by the same EF11 instrument on a second flight through an auroral arc in 1981 are also presented. Two types of atomic oxygen variability were found in both of the flights. In the first type, [O] is increased above [O-MSIS] by a factor of 1.5 at 180 km, is equal to the MSIS model at 160 km, and is less than MSIS below that; that is, the scale height of [O] was increased. The experimental I(557.7)/I(391.4) ratio was constant with altitude. In the second type, the [O] was depleted by about a factor of 2 over the altitude range of 120-180 km, while the I(557.7)/I(391.4) ratio decreased with altitude. The inferred atomic oxygen concentrations of 0.5 to 2 with respect to MSIS suggested different vertical flows on the two cases. Independent evidence is provided by atmospheric composition measurements made during the same campaign.

  10. First Hubble Space Telescope Movies of Jupiter’s Ultraviolet Aurora During the NASA Juno Prime Mission

    OpenAIRE

    Grodent, Denis; Gladstone, G. Randall; Clarke, John T.; Bonfond, Bertrand; Gérard, Jean-Claude; Radioti, Aikaterini; Nichols, John D.; Bunce, Emma J.; Roth, Lorenz; Saur, Joachim; Kimura, Tomoki; Orton, Glenn S.; Badman, Sarah V.; Mauk, Barry; Connerney, John E P

    2016-01-01

    The primary goal of this HST campaign is to complement Juno-UVS (Ultraviolet Spectrograph) observations. This complementarity is four-fold as HST observes Jupiter’s aurora when: 1) Juno-UVS is turned off, that is about 98% of Juno’s 14-day orbit, and Juno’s in situ instruments are in operation. 2) Juno-UVS is operating, but observes the opposite hemisphere of Jupiter. 3) UVS is on in the same hemisphere, but too close to Jupiter to have a global, contextual, view of the aurora and/or UVS is a...

  11. Occurrence of multipolar mitoses and association with Aurora-A/-B kinases and p53 mutations in aneuploid esophageal carcinoma cells

    Directory of Open Access Journals (Sweden)

    Münch Claudia

    2011-04-01

    Full Text Available Abstract Background Aurora kinases and loss of p53 function are implicated in the carcinogenesis of aneuploid esophageal cancers. Their association with occurrence of multipolar mitoses in the two main histotypes of aneuploid esophageal squamous cell carcinoma (ESCC and Barrett's adenocarcinoma (BAC remains unclear. Here, we investigated the occurrence of multipolar mitoses, Aurora-A/-B gene copy numbers and expression/activation as well as p53 alterations in aneuploid ESCC and BAC cancer cell lines. Results A control esophageal epithelial cell line (EPC-hTERT had normal Aurora-A and -B gene copy numbers and expression, was p53 wild type and displayed bipolar mitoses. In contrast, both ESCC (OE21, Kyse-410 and BAC (OE33, OE19 cell lines were aneuploid and displayed elevated gene copy numbers of Aurora-A (chromosome 20 polysomy: OE21, OE33, OE19; gene amplification: Kyse-410 and Aurora-B (chromosome 17 polysomy: OE21, Kyse-410. Aurora-B gene copy numbers were not elevated in OE19 and OE33 cells despite chromosome 17 polysomy. Aurora-A expression and activity (Aurora-A/phosphoT288 was not directly linked to gene copy numbers and was highest in Kyse-410 and OE33 cells. Aurora-B expression and activity (Aurora-B/phosphoT232 was higher in OE21 and Kyse-410 than in OE33 and OE19 cells. The mitotic index was highest in OE21, followed by OE33 > OE19 > Kyse-410 and EPC-hTERT cells. Multipolar mitoses occurred with high frequency in OE33 (13.8 ± 4.2%, followed by OE21 (7.7 ± 5.0% and Kyse-410 (6.3 ± 2.0% cells. Single multipolar mitoses occurred in OE19 (1.0 ± 1.0% cells. Distinct p53 mutations and p53 protein expression patterns were found in all esophageal cancer cell lines, but complete functional p53 inactivation occurred in OE21 and OE33 only. Conclusions High Aurora-A expression alone is not associated with overt multipolar mitoses in aneuploid ESCC and BAC cancer cells, as specifically shown here for OE21 and OE33 cells, respectively

  12. Simulation of transition from Townsend mode to glow discharge mode in a helium dielectric barrier discharge at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    Li Xue-Chen; Niu Dong-Ying; Xu Long-Fei; Jia Peng-Ying; Chang Yuan-Yuan

    2012-01-01

    The dielectric barrier discharge characteristics in helium at atmospheric pressure are simulated based on a one-dimensional fluid model.Under some discharge conditions,the results show that one discharge pulse per half voltage cycle usually appears when the amplitude of external voltage is low,while a glow-like discharge occurs at high voltage.For the one discharge pulse per half voltage cycle,the maximum of electron density appears near the anode at the beginning of the discharge,which corresponds to a Townsend discharge mode.The maxima of the electron density and the intensity of electric field appear in the vicinity of the cathode when the discharge current increases to some extent,which indicates the formation of a cathode-fall region.Therefore,the discharge has a transition from the Townsend mode to the glow discharge mode during one discharge pulse,which is consistent with previous experimental results.

  13. Study of the glow dynamics in a laser-produced plasma jet expanding across the magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Bessarab, A. V.; Bondarenko, G. A.; Garanin, S. G.; Zhidkov, N. V.; Nikitin, I. N.; Starodubtsev, V. A.; Sungatullin, R. R. [All-Russia Research Institute of Experimental Physics, Russian Federal Nuclear Center (Russian Federation)

    2011-09-15

    Results are presented from experimental studies of the glow dynamics of a plasma jet generated during the irradiation of a plane aluminum target by an iodine laser pulse with the wavelength 1.315 {mu}m. The laser pulse energy was 330-480 J, the pulse duration was 0.5 ns, and the focal spot diameter was 3 mm, the laser intensity on the target surface being {approx}10{sup 13} W/cm{sup 2}. The jet expanded across an external magnetic field with the strength {approx}1 kOe. The residual air pressure in the vacuum chamber was {approx}10{sup -5} Torr. The spatiotemporal behavior of the jet glow was investigated using a nine-frame camera in two mutually perpendicular directions (along and across the magnetic field). The results of measurements indicate azimuthal asymmetry of the jet expansion.

  14. XPS study of the corrosion resisting composite alloying layer obtained by double glow plasma with the brush plating Ni interlayer

    Institute of Scientific and Technical Information of China (English)

    Jiang Xu; Xishan Xie; Zhong Xu; Wenjin Liu

    2004-01-01

    The Ni-Cr-Mo-Cu multi-element surface alloying with the electric brush plating Ni interlayer on the low carbon steel substrate has been investigated. By the electrochemical method in 3.5% (mass fraction) NaC1 solution, the corrosion resistance of the composite alloying layer and single alloying layer is determined. The experimental results show that the corrosion resistance of the composite alloying layer is obviously better than that of the single alloying layer. The structure and composition of passive films formed on the two kinds of alloyed layers after electrochemical tests in 3.5% NaC1 solution have been studied using X-ray photoelectron spectroscopy (XPS). It is concluded that the double glow plasma surface alloying of low carbon steel with the electric brush plating Ni interlayer is an appropriate technique to enhance the corrosion resistance compared with the single double glow surface alloying.

  15. Analysis of read-out heating rate effects on the glow peaks of TLD-100 using WinGCF software

    Energy Technology Data Exchange (ETDEWEB)

    Bauk, Sabar, E-mail: sabar@usm.my [Physics Section, School of Distance Education, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Hussin, Siti Fatimah [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Alam, Md. Shah [Physics Section, School of Distance Education, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Physics Department, Shahjalal University of Science and Technology, Sylhet (Bangladesh)

    2016-01-22

    This study was done to analyze the effects of the read-out heating rate on the LiF:Mg,Ti (TLD-100) thermoluminescent dosimeters (TLD) glow peaks using WinGCF computer software. The TLDs were exposed to X-ray photons with a potential difference of 72 kVp and 200 mAs in air and were read-out using a Harshaw 3500 TLD reader. The TLDs were read-out using four read-out heating rates at 10, 7, 4 and 1 °C s{sup −1}. It was observed that lowering the heating rate could separate more glow peaks. The activation energy for peak 5 was found to be lower than that for peak 4. The peak maximum temperature and the integral value of the main peak decreased as the heating rate decreases.

  16. STUDY ON THE TANTALIZING ON THE SURFACE OF TITANIUM ALLOY BY NET-SHAPE CATHODE GLOW DISCHARGING

    Institute of Scientific and Technical Information of China (English)

    F. Chen; H. Zhou; Y.F. Zhang; J.D. Pan

    2005-01-01

    A new net-shape cathode sputtering target which has a simple structure and a high sputtering was put forward. The multiple-structure made of alloying and coating layers of tantalum was achieved on the surface of TC4 (Ti6Al4V) using this method in double glow surface alloying process. The tantalized samples were investigated by SEM, XRD and electrochemical corrosion method .Results show the complicated tissue of pure tantalizing layer and diffusion layer was successfully formed on the surface of TC4 with the method of net-shape cathode glow discharge, which further improved the corrosion-resistance of TC4 and formed good corrosion-resistant alloys.

  17. Plasma boronizing of Ti6AlV4 using solid precursors by double glow plasma alloying technique

    Institute of Scientific and Technical Information of China (English)

    QIN Lin; QU Jun-zhi; LIN Nai-ming; FAN Ai-lan; CHANG Da-qing; TANG Bin

    2006-01-01

    Solid state B-offerings (FeB compound) were used for plasma-assisted boronizing on Ti6Al4V alloy by double glow discharge plasma alloying technique (DGPSA). During all experiment processing there was no harmful and toxic. The thickness and morphology, phase formation, elements concentrations and wear properties of boride layers were examined by means of optical microscopy, Vickers microhardness, X-ray diffraction, glow discharge optical emission spectroscopy and Ball-disk wear tests. The results show that friction coefficient of boride alloying samples versus corundum ball is lower than that of Ti6Al4V samples, as well as wear rate. This indicates that plasma-assisted boronizing of Ti6Al4V alloy has a high potential for industrial applications under tribological conditions.

  18. The Pale Green Dot: A Method to Characterize Proxima Centauri b using Exo-Aurorae

    CERN Document Server

    Luger, Rodrigo; Fleming, David P; Tilley, Matt A; Agol, Eric; Meadows, Victoria S; Deitrick, Russell; Barnes, Rory

    2016-01-01

    We examine the feasibility of detecting auroral emission from the potentially habitable exoplanet Proxima Centauri b. This planet's active, late-type M dwarf host makes detection of aurorae more favorable than around a solar-type star, primarily by increasing auroral power and improving the planet-star contrast in the visible wavelength range due to strong TiO absorption in the star. Detection of aurorae would yield an independent confirmation of the planet's existence, constrain the presence and composition of its atmosphere, and determine the planet's eccentricity and inclination, thereby breaking the mass-inclination degeneracy. If Proxima b is a terrestrial world with an atmosphere and magnetic field, we estimate that its auroral power at the 5577\\AA\\ OI auroral line is on the order of 0.1 TW under steady-state stellar wind, or ~100 times stronger than that on Earth. This corresponds to a planet-star contrast ratio of $10^{-6}-10^{-7}$ in a narrow band about the 5577\\AA\\ line, although higher contrast ($1...

  19. Aurora kinase A induces papillary thyroid cancer lymph node metastasis by promoting cofilin-1 activity.

    Science.gov (United States)

    Maimaiti, Yusufu; Jie, Tan; Jing, Zhou; Changwen, Wang; Pan, Yu; Chen, Chen; Tao, Huang

    2016-04-22

    Aurora-A (Aur-A), a member of the serine/threonine Aurora kinase family, plays an important role in ensuring genetic stability during cell division. Previous studies indicated that Aur-A possesses oncogenic activity and may be a valuable therapeutic target in cancer therapy. However, the role of Aur-A in the most common thyroid cancer, papillary thyroid cancer (PTC), remains largely unknown. In patients with PTC, cancer cell migration and invasion account for most of the metastasis, recurrence, and cancer-related deaths. Cofilin-1 (CFL-1) is the most important effector of actin polymerization and depolymerization, determining the direction of cell migration. Here, we assessed the correlation between Aur-A and CFL-1 in PTC with lymph node metastasis. Tissue microarray data showed that simultaneous overexpression of Aur-A and CFL-1 correlated with lymph node metastasis in thyroid cancer tissue. Inhibition of Aur-A suppressed thyroid cancer cell migration in vitro and decreased lymph node metastasis in nude mice. Importantly, Aur-A increased the non-phosphorylated, active form of CFL-1 in TPC-1 cells, thus promoting cancer cell migration and thyroid cancer lymph node metastasis. Our findings indicate that the combination of Aur-A and CFL-1 may be useful as a molecular prediction model for lymph node metastasis in thyroid cancer and raise the possibility of targeting Aur-A and CFL-1 for more effective treatment of thyroid cancer.

  20. New benzimidazoles and their antitumor effects with Aurora A kinase and KSP inhibitory activities.

    Science.gov (United States)

    Abd El-All, Amira S; Magd-El-Din, Asmaa A; Ragab, Fatma A F; ElHefnawi, Mahmoud; Abdalla, Mohamed M; Galal, Shadia A; El-Rashedy, Ahmed A

    2015-07-01

    A newly synthesized series of anticancer compounds comprising thiazolo[3,2-a]pyrimidine derivatives 6a-q bearing a benzimidazole moiety was produced via a one-pot reaction of N-(4-(1H-benzo[d]imidazol-2-yl)phenyl)-2-cyanoacetamide 5 with 2-aminothiazole and an appropriate aromatic aldehyde. Compound 7 was obtained via the reaction of 4-(1H-benzo[d]imidazol-2yl)benzenamide 1 with carbon disulphide and methyl iodide in the presence of concentrated aqueous solution of NaOH, then treated with o-phenylenediamine to give N-(4-1H-benzo[d]imidazol-2-yl)phenyl)-1H-benzo[d]imidazol-2-amine 8. The structures of the newly synthesized compounds were confirmed by analytical and spectroscopic measurements (IR, MS, and (1) H NMR). The synthesized products were screened and studied for their in vitro antitumor activity against three human cancer cell lines (namely colorectal cancer cell line HCT116, human liver cancer cell line HepG2, and human ovarian cancer cell line A2780) and their Aurora A kinase and KSP inhibitory activities. All newly synthesized compounds revealed marked results comparable with the standard drug CK0106023. The compounds 6e and 6k of the thiazolopyrimidine derivatives were the most active compounds when tested against the three cell lines in comparison with the standard drug CK0106023, and showed potent dual KSP and Aurora A kinase inhibition.

  1. Long-term Spatial and Temporal Variations of Aurora Borealis Events in the Period 1700 - 1905

    Science.gov (United States)

    Vázquez, M.; Vaquero, J. M.; Gallego, M. C.

    2014-05-01

    Catalogues and other records of aurora-borealis events were used to study the long-term spatial and temporal variation of these phenomena in the period from 1700 to 1905 in the Northern Hemisphere. For this purpose, geographic and geomagnetic coordinates were assigned to approximately 27 000 auroral events with more than 80 000 observations. They were analyzed separately in three large-scale areas: i) Europe and North Africa, ii) North America, and iii) Asia. There was a clear need to fill some gaps existing in the records so as to have a reliable proxy of solar activity, especially during the 18th century. In order to enhance the long-term variability, an 11-year smoothing window was applied to the data. Variations in the cumulative numbers of auroral events with latitude (in both geographic and geomagnetic coordinates) were used to discriminate between the two main solar sources: coronal mass ejections and high-speed streams from coronal holes. The characteristics of the associated auroras correlate differently with the solar-activity cycle.

  2. Aurora B kinase is a potent and selective target in MYCN-driven neuroblastoma.

    Science.gov (United States)

    Bogen, Dominik; Wei, Jun S; Azorsa, David O; Ormanoglu, Pinar; Buehler, Eugen; Guha, Rajarshi; Keller, Jonathan M; Mathews Griner, Lesley A; Ferrer, Marc; Song, Young K; Liao, Hongling; Mendoza, Arnulfo; Gryder, Berkley E; Sindri, Sivasish; He, Jianbin; Wen, Xinyu; Zhang, Shile; Shern, John F; Yohe, Marielle E; Taschner-Mandl, Sabine; Shohet, Jason M; Thomas, Craig J; Martin, Scott E; Ambros, Peter F; Khan, Javed

    2015-11-01

    Despite advances in multimodal treatment, neuroblastoma (NB) is often fatal for children with high-risk disease and many survivors need to cope with long-term side effects from high-dose chemotherapy and radiation. To identify new therapeutic targets, we performed an siRNA screen of the druggable genome combined with a small molecule screen of 465 compounds targeting 39 different mechanisms of actions in four NB cell lines. We identified 58 genes as targets, including AURKB, in at least one cell line. In the drug screen, aurora kinase inhibitors (nine molecules) and in particular the AURKB-selective compound, barasertib, were the most discriminatory with regard to sensitivity for MYCN-amplified cell lines. In an expanded panel of ten NB cell lines, those with MYCN-amplification and wild-type TP53 were the most sensitive to low nanomolar concentrations of barasertib. Inhibition of the AURKB kinase activity resulted in decreased phosphorylation of the known target, histone H3, and upregulation of TP53 in MYCN-amplified, TP53 wild-type cells. However, both wild-type and TP53 mutant MYCN-amplified cell lines arrested in G2/M phase upon AURKB inhibition. Additionally, barasertib induced endoreduplication and apoptosis. Treatment of MYCN-amplified/TP53 wild-type neuroblastoma xenografts resulted in profound growth inhibition and tumor regression. Therefore, aurora B kinase inhibition is highly effective in aggressive neuroblastoma and warrants further investigation in clinical trials.

  3. Aurora A Kinase Contributes to a Pole-Based Error Correction Pathway.

    Science.gov (United States)

    Ye, Anna A; Deretic, Jovana; Hoel, Christopher M; Hinman, Albert W; Cimini, Daniela; Welburn, Julie P; Maresca, Thomas J

    2015-07-20

    Chromosome biorientation, where sister kinetochores attach to microtubules (MTs) from opposing spindle poles, is the configuration that best ensures equal partitioning of the genome during cell division. Erroneous kinetochore-MT attachments are commonplace but are often corrected prior to anaphase. Error correction, thought to be mediated primarily by the centromere-enriched Aurora B kinase (ABK), typically occurs near spindle poles; however, the relevance of this locale is unclear. Furthermore, polar ejection forces (PEFs), highest near poles, can stabilize improper attachments by pushing mal-oriented chromosome arms away from spindle poles. Hence, there is a conundrum: erroneous kinetochore-MT attachments are weakened where PEFs are most likely to strengthen them. Here, we report that Aurora A kinase (AAK) opposes the stabilizing effect of PEFs. AAK activity contributes to phosphorylation of kinetochore substrates near poles and its inhibition results in chromosome misalignment and an increased incidence of erroneous kinetochore-MT attachments. Furthermore, AAK directly phosphorylates a site in the N-terminal tail of Ndc80/Hec1 that has been implicated in reducing the affinity of the Ndc80 complex for MTs when phosphorylated. We propose that an AAK activity gradient contributes to correcting mal-oriented kinetochore-MT attachments in the vicinity of spindle poles.

  4. Jovian Mid-Infrared Aurora, Hydrocarbon Abundances and Temperature Prior to Juno's Arrival

    Science.gov (United States)

    Kostiuk, Theodor; Livengood, Timothy A.; Hewagama, Tilak; Kolasinski, John

    2016-10-01

    We report on ground-based measurements of Jupiter's thermal infrared aurora, ethane abundances and temperature prior to Juno's arrival at Jupiter in July 2016. Measurements covering spectral and altitude regions that will complement Juno observational capabilities were made April 18-22, 2016, with the GSFC Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) on the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. The ultra-high spectral resolution infrared heterodyne spectroscopy (IRHS) measures fully resolved individual spectral lines whose shape provides unique information on variability of temperature and abundance. Ethane line spectra near 12-micrometer wavelength will be used to determine the intensities of auroral emission from Jupiter's polar regions and retrieve ethane abundance and temperature changes on and off the north polar "hot spot" region. Results will be compared to a 30-year study of this thermal infrared aurora with ground-based IRHS and with Voyager IRIS and Cassini CIRS measurements. Additional measurements during Juno's orbital mission phase are also planned. Analyses of the variability of the earlier measurements suggest that the thermal IR auroral emission may be low during the Juno -Jupiter encounter. Results will be useful for the Juno mission, since it does not have instrumentation in this spectral region and this work provides complementary information and diagnostic for studying Jupiter in a spectral region and altitude range not directly probed by Juno.

  5. Precipitation of relativistic electrons of the Van Allen belts into the proton aurora

    Energy Technology Data Exchange (ETDEWEB)

    Jordanova, Vania K [Los Alamos National Laboratory; Miyoshi, Y [NAGOYA UNIV; Sakaguchi, K [NAGOYA UNIV; Shiokawa, K [NAGOYA UNIV; Evans, D S [SEC/NOAA; Albert, Jay [AFRL; Connors, M [UNIV OF ATHABASCA

    2008-01-01

    The Van Allen electron belts consist of two regions encircling the earth in which relativistic electrons are trapped in the earth's magnetic field. Populations of relativistic electrons in the Van Allen belts vary greatly with geomagnetic disturbance and they are a major source of damage to space vehicles. In order to know when and by how much these populations of relativistic electrons increase, it is important to elucidate not only the cause of acceleration of relativistic electrons but also the cause of their loss from the Van Allen belts. Here we show the first evidence that left-hand polarized electromagnetic ion cyclotron (EMIC) plasma waves can cause the loss of relativistic electrons into the atmosphere, on the basis of results of an excellent set of ground and satellite observations showing coincident precipitation of ions with energies of tens of keV and of relativistic electrons into an isolated proton aurora. The proton aurora was produced by precipitation of ions with energies of tens of keV due to EMIC waves near the plasma pause, which is a manifestation of wave-particle interactions. These observations clarify that ions with energies of tens of keV affect the evolution of relativistic electrons in the Van Allen belts via parasitic resonance with EMIC waves, an effect that was first theoretically predicted in the early 1970's.

  6. [Effect of aurora inhibitor VX-680 on proliferation and apoptosis of CML cells].

    Science.gov (United States)

    Yin, Yue; Sun, Hui-Yan; Li, Xiao-Lin; Xiao, Feng-Jun; Wang, Li-Sheng

    2014-12-01

    This study was aimed to explore the effect of VX-680, an aurora inhibitor, on proliferation and apoptosis of K562, KCL22 cell lines and CD34⁺ cells from chronic myeloid leukemia (CML) patients in vitro. The proliferation of K562 and KCL22 cell was detected by CCK-8 method. Apoptosis of cells was detected by Annexin V-PI labeling and flow cytometry. The colony forming ability of bone marrow CD34⁺ cells derived from CML patients and donors was determined by the colony forming test. The results showed that the treatment of K562, KCL22 and CML CD34⁺ cells with VX-680 of 20-100 nmol/L for 3 days could obviously inhibit the cell proliferation in a concentration-dependent manner (P VX-680 treatment significantly induced apoptosis of K562 and KCL22 cells. Compared to bone marrow CD34⁺ cells derived from the healthy donors, the colony forming ability of CML CD34⁺ cells derived from bone marrow of CML patients was remarkably reduced (P VX-680, an aurora inhibitor, can inhibit the proliferation and induce apoptosis of CML cells in vitro.

  7. On the increase in the limiting current of an atmospheric-pressure glow discharge in an argon flow

    Science.gov (United States)

    Baldanov, B. B.; Ranzhurov, Ts. V.

    2014-04-01

    The initiation of an atmospheric-pressure glow discharge (APGD) is studied in the multitip cathode-planar anode electrode system through which an argon flow passes. It is shown that sectioning of the cathode and ballast resistances present at corona tips make it possible to substantially expand the current region of the discharge and considerably raise the limiting current of the APGD. The shape of the coronafree electrode is found to influence the limiting discharge current.

  8. Aspects of the practical application of titanium alloys after low temperature nitriding glow discharge in hydrogen- free -gas media

    Science.gov (United States)

    Mashovets, N. S.; Pastukh, I. M.; Voloshko, S. M.

    2017-01-01

    X-ray diffraction analysis, X-ray photoelectron spectroscopy, and Electron Auger-spectroscopy investigation of phase transformation on the surface of the VT8 titanium alloy after a low temperature hydrogen-free nitriding in a glow discharge. Operational characteristics of titanium alloys defined physical-mechanical characteristics of the surface and their phase composition, which depend on the process parameters of nitriding. Surface modification of titanium alloys were carried out by low-temperature nitriding in a glow discharge in hydrogen-free environment. The main advantage of this method lies in the absence of hydrogen embrittlement and complete environmental safety process. Application of the glow discharge can not only speed up the process by the order of the diffusion surface saturation with nitrogen, but also significantly alters the kinetics of the process and quality of the nitrided layer, in particular its physio-mechanical properties and phase composition. For research purposes, the standards from an α + β alloy Ti-Al6-Cr2-Mo2,5 (VT8) were used. Research into the phase composition was performed by X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Stratified analysis by AES was conducted by etching the surface of the samples' argon ion beam with diameters of 1.5 mm with an energy of 3000 eV and a current density of 400 mA/cm2. The above material shows the promise of the technology of low-temperature hydrogen-nitriding by glow discharge. This greatly expands the range of practical applications of titanium alloys. In addition, changing the technological mode allows you to manage a wide range of modified phase composition of the surface layer and as a result - to form the surface of titanium parts, taking into account the conditions of the subsequent operation.

  9. Sputtered-deposited thin brass films in a modified glow discharge Grimm-type source

    Science.gov (United States)

    Grais, K. I.; Eid, M. A.; Tawfik, N. L.; Abd-El-Aal, M. S.; Shaltout, A. A.

    2006-08-01

    Modification of the non-assisted gas flow-line across the target surface in a Grimm-type glow discharge source is described. The new flow line permits the gas to flow through a cylindrical annular space ending with a disc-space annular gap, facing the target surface. This configuration would cause directed jet assisted gas flow rays to impinge on infinite points across the cathode surface. Improvement has been achieved in the V-I characteristics where Δ V/Δ I increases from 1.8 to 3.5 V/mA. The sputtering as well as simultaneous deposition rates, have been increased by a factor of 16 and 17 respectively. These roll over with increasing sputtering time, their maximum values at a characteristic time, toc of 21 min. The toc value was constant for different operating parameters provided that the source geometry assembly is kept fixed. The presence of a glass substrate in the anode cavity has, apparently, no effect on the obtained data. Improvements have also been achieved in the crater profile, characterized by an approximately flat crater bottom with nearly vertical walls, and less re-deposited particles on the crater depth and edge. Fixing the distance Z of the substrate from target surface, along the cell axis, and varying the deposition time from 1 to 30 min, a sequence of changes in the deposited film were observed by X-ray diffraction and energy dispersion X-ray (EDX). These changes start with an amorphous structure, followed by the appearance of Cu and Zn crystallites and a probable deposition of Cu{5}Zn{8} clusters. The profile of the number of sputtered particles at different Z values is characterized by a number of peaks and troughs. This behavior has been explained by the occurrence of local cluster-dissociation and formation, by different collision processes. The improvements achieved by the application of the present jet assisted gas flow can be of value in the analytical application of this type of glow discharge.

  10. Effects of traces of molecular gases (hydrogen, nitrogen) in glow discharges in noble gases

    Science.gov (United States)

    Steers, E. B. M.; Smid, P.; Hoffmann, V.

    2008-07-01

    The "Grimm" type of low pressure glow discharge source, introduced some forty years ago, has proved to be a versatile analytical source. A flat sample is used as the cathode and placed about 0.2mm away from the end of a hollow tubular anode leading to an obstructed discharge. When the source was first developed, it was used for the direct analysis of solid metallic samples by optical emission spectroscopy (OES), normally with argon as the plasma gas; it was soon found that, using suitable electrical parameters, the cathode material was sputtered uniformly from a circular crater of diameter equal to that of the tubular anode, so that the technique could be used for compositional depth profile analysis (CDPA). Over the years the capability and applications of the technique have steadily increased. The use of rf powered discharges now permits the analysis of non-conducting layers and samples; improved instrumental design now allows CDPA of ever thinner layers (e.g. resolution of layers 5 nm thick in multilayer stacks is possible). For the original bulk material application, pre-sputtering could be used to remove any surface contamination but for CDPA, analysis must start immediately the discharge is ignited, so that any surface contamination can introduce molecular gases into the plasma gas and have significant analytical consequences, especially for very thin layers; in addition, many types of samples now analysed contain molecular gases as components (either as occluded gas, or e.g. as a nitride or oxide), and this gas enters the discharge when the sample is sputtered. It is therefore important to investigate the effect of such foreign gases on the discharge, in particular on the spectral intensities and hence the analytical results. The presentation will concentrate mainly on the effect of hydrogen in argon discharges, in the concentration range 0-2 % v/v but other gas mixtures (e.g. Ar/N_2, Ne/H_2) will be considered for comparison. In general, the introduction of

  11. DC negative corona discharge in atmospheric pressure helium: transition from the corona to the ‘normal’ glow regime

    Science.gov (United States)

    Hasan, Nusair; Antao, Dion S.; Farouk, Bakhtier

    2014-06-01

    Direct current (dc) negative corona discharges in atmospheric pressure helium are simulated via detailed numerical modeling. Simulations are conducted to characterize the discharges in atmospheric helium for a pin plate electrode configuration. A self-consistent two-dimensional hybrid model is developed to simulate the discharges and the model predictions are validated with experimental measurements. The discharge model considered consists of momentum and energy conservation equations for a multi-component (electrons, ions, excited species and neutrals) gas mixture, conservation equations for each component of the mixture and state relations. A drift-diffusion approximation for the electron and the ion fluxes is used. A model for the external circuit driving the discharge is also considered and solved along with the discharge model. Many of the key features of a negative corona discharge, namely non-linear current-voltage characteristics, spatially flat cathode current density and glow-like discharge in the high current regime are displayed in the predictions. A transition to the ‘normal’ glow discharge from the corona discharge regime is also observed. The transition is identified from the calculated current-voltage characteristic curve and is characterized by the radial growth of the negative glow and the engulfment of the cathode wire.

  12. Model Insensitive and Calibration Independent Method for Determination of the Downstream Neutral Hydrogen Density Through Ly-alpha Glow Observations

    Science.gov (United States)

    Gangopadhyay, P.; Judge, D. L.

    1996-01-01

    Our knowledge of the various heliospheric phenomena (location of the solar wind termination shock, heliopause configuration and very local interstellar medium parameters) is limited by uncertainties in the available heliospheric plasma models and by calibration uncertainties in the observing instruments. There is, thus, a strong motivation to develop model insensitive and calibration independent methods to reduce the uncertainties in the relevant heliospheric parameters. We have developed such a method to constrain the downstream neutral hydrogen density inside the heliospheric tail. In our approach we have taken advantage of the relative insensitivity of the downstream neutral hydrogen density profile to the specific plasma model adopted. We have also used the fact that the presence of an asymmetric neutral hydrogen cavity surrounding the sun, characteristic of all neutral densities models, results in a higher multiple scattering contribution to the observed glow in the downstream region than in the upstream region. This allows us to approximate the actual density profile with one which is spatially uniform for the purpose of calculating the downstream backscattered glow. Using different spatially constant density profiles, radiative transfer calculations are performed, and the radial dependence of the predicted glow is compared with the observed I/R dependence of Pioneer 10 UV data. Such a comparison bounds the large distance heliospheric neutral hydrogen density in the downstream direction to a value between 0.05 and 0.1/cc.

  13. An Optical Atmospheric Phenomenon Observed in 1670 over the City of Astrakhan Was Not a Mid-Latitude Aurora

    Science.gov (United States)

    Usoskin, I. G.; Kovaltsov, G. A.; Mishina, L. N.; Sokoloff, D. D.; Vaquero, J.

    2017-01-01

    It has recently been claimed (Zolotova and Ponyavin Solar Phys., 291, 2869, 2016; ZP16 henceforth) that a mid-latitude optical phenomenon, which took place over the city of Astrakhan in July 1670, according to Russian chronicles, were a strong aurora borealis. If this were true, it would imply a very strong or even severe geomagnetic storm during the quietest part of the Maunder minimum. However, as we argue in this article, this conclusion is erroneous and caused by a misinterpretation of the chronicle record. As a result of a thorough analysis of the chronicle text, we show that the described phenomenon occurred during the daylight period of the day ("the last morning hour"), in the south ("towards noon"), and its description does not match that of an aurora. The date of the event was also interpreted incorrectly. We conclude that this phenomenon was not a mid-latitude aurora, but an atmospheric phenomenon, the so-called sundog (or parhelion), which is a particular type of solar halo. Accordingly, the claim of a strong mid-latitude aurora during the deep Maunder Minimum is not correct and should be dismissed.

  14. A comparative study of the aneugenic and polyploidy-inducing effects of fisetin and two model Aurora kinase inhibitors.

    Science.gov (United States)

    Gollapudi, P; Hasegawa, L S; Eastmond, D A

    2014-06-01

    Fisetin, a plant flavonol commonly found in fruits, nuts and vegetables, is frequently added to nutritional supplements due to its reported cardioprotective, anti-carcinogenic and antioxidant properties. Earlier reports from our laboratory and others have indicated that fisetin has both aneugenic and clastogenic properties in cultured cells. More recently, fisetin has also been reported to target Aurora B kinase, a Ser/Thr kinase involved in ensuring proper microtubule attachment at the spindle assembly checkpoint, and an enzyme that is overexpressed in several types of cancer. Here we have further characterized the chromosome damage caused by fisetin and compared it with that induced by two known Aurora kinase inhibitors, VX-680 and ZM-447439, in cultured TK6 cells using the micronucleus assay with CREST staining as well as a flow cytometry-based assay that measures multiple types of numerical chromosomal aberrations. The three compounds were highly effective in inducing aneuploidy and polyploidy as evidenced by increases in kinetochore-positive micronuclei, hyperdiploidy, and polyploidy. With fisetin, however, the latter two effects were most significantly observed only after cells were allowed to overcome a cell cycle delay, and occurred at higher concentrations than those induced by the other Aurora kinase inhibitors. Modest increases in kinetochore-negative micronuclei were also seen with the model Aurora kinase inhibitors. These results indicate that fisetin induces multiple types of chromosome abnormalities in human cells, and indicate a need for a thorough investigation of fisetin-augmented dietary supplements.

  15. Lower-thermospheric wind fluctuations measured with an FPI during pulsating aurora at Tromsø, Norway

    Directory of Open Access Journals (Sweden)

    S. Oyama

    2010-10-01

    Full Text Available Simultaneous observations were conducted with a Fabry-Perot Interferometer (FPI at a wavelength of 557.7 nm, an all-sky camera at a wavelength of 557.7 nm, and the European Incoherent Scatter (EISCAT UHF radar during the Dynamics and Energetics of the Lower Thermosphere in Aurora 2 (DELTA-2 campaign in January 2009. This paper concentrated on two events during periods of pulsating aurora. The lower-thermospheric wind velocity measured with the FPI showed obvious fluctuations in both vertical and horizontal components. Of particular interest is that the location of the fluctuations was found in a darker area that appeared within the pulsating aurora. During the same time period, the EISCAT radar observed sporadic enhancements in the F-region backscatter echo power, which suggests the presence of low-energy electron (1 keV or lower precipitation coinciding with increase in amplitude of the electromagnetic wave (at the order of 10 Hz or higher. While we have not yet identified the dominant mechanism causing the fluctuations in FPI-derived wind velocity during the pulsating aurora, the frictional heating energy dissipated by the electric-field perturbations may be responsible for the increase in ionospheric thermal energy thus modifying the local wind dynamics in the lower thermosphere.

  16. Dithiocarbamate promoted practical synthesis of N-Aryl-2-aminobenzazoles: Synthesis of novel Aurora-A kinase inhibitor

    Indian Academy of Sciences (India)

    Naresh Kumar Katari; M Venkatanarayana; Kummari Srinivas

    2015-03-01

    Various N-aryl-2-aminobenzoxazoles and N-aryl-2-aminobenzothiazoles were synthesized from o-aminophenol and o-aminothiophenol, respectively, mediated by dithiocarbamate in one step. The salient features of this method include mild reaction condition, high yield and large scale synthesis. Application of this methodology has been demonstrated by synthesizing potent Aurora kinase-A inhibitors.

  17. Independencia y su expresión léxica en la Aurora de Chile Independence and its lexical expression in the Aurora de Chile

    Directory of Open Access Journals (Sweden)

    Mariano Franco Figueroa

    2010-01-01

    Full Text Available Tomando como base documental el semanario Aurora de Chile, se realiza un análisis lingüístico que describe las caracterizaciones léxicas acomodadas a los nuevos contextos sociolingüísticos en esta época histórica de la independencia colonial y los fenómenos gramaticales que permiten observar rasgos diferenciadores en la lengua que se asienta en esta sociedad chilena. Por una parte, resulta interesante constatar la variación léxica que este texto periodístico, portavoz de una ideología ilustrada, proporciona para alcanzar un mejor conocimiento del grado de penetración del nuevo léxico político-social, con voces en muchos casos recreadas con las acepciones dominantes en las comunidades insurgentes. Por otra, la descripción de los fenómenos gramaticales y del léxico general de este corpus aporta datos concretos acerca de la preferencia de estas variantes lingüísticas y del grado de estandarización que van adquiriendo, como usos emergentes de la lengua española en Chile, bien como asentamientos de estructuras sintácticas y de léxico tradicionales o bien como mecanismos innovadores en la gramática y en el vocabulario diferencial americano.Based on the weekly newspaper Aurora de Chile, a linguistic analysis is here introduced including both the description of lexical characterizations as they adapted to the new sociolinguistic contexts in the historical period of the colonial emancipation and the grammatical phenomena that allow for the observation of differentiating features of the language being established in the Chilean society of the time. On the one hand, it is of interest to observe the lexical variation displayed in this journalistic text, which represents an illustrated ideology, in order to better understand the degree of penetration of the new political and social vocabulary, with voices in many cases recreated with uses dominating the insurgent communities. On the other hand, the description of the grammatical

  18. Optical investigations of high pressure glow discharges based on MSE arrays

    Energy Technology Data Exchange (ETDEWEB)

    Penache, C.; Hohn, O.; Schmidt-Boecking, H. [Frankfurt Univ. (Germany); Spielberger, L. [Deutsche Gesellschaft fuer Technische Zusammenarbeit GmbH (GTZ), Eschborn (Germany); Braeuning-Demian, A.; Penache, D. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)

    2001-07-01

    The micro-structure-electrode (MSE) arrays are providing a non-thermal high pressure plasma. These arrays consist of a matrix of holes perforated in a thin multilayer made out of two metallic foils separated by a dielectric. The holes diameter and the thickness of the insulator spacer need to be around 100 {mu}m to allow for the MSE operation at pressure ranging from 0.1 to 1 bar and above. In this work single direct current microdischarges and systems of parallel operated holes in argon at 0.2 bar have been optically investigated. The spatial distribution of the emitted light has been monitored by a digital camera connected to an optical microscope. The UV photon emission has been recorded by a position sensitive photon detector allowing for space and time resolved measurements. Its time resolution of about 1 nsec makes possible the investigation of fast processes, e.g. the constriction of the discharge. Due to its typical position resolution of 100 {mu}m, this detector needs to be used in combination with an optical system allowing for the magnification of the discharge area. The optical appearance show a stable, volume filling glow discharge, fact proved also by the typical current-voltage characteristic.

  19. Simulation of radio-frequency atmospheric pressure glow discharge in γ mode

    Institute of Scientific and Technical Information of China (English)

    Shang Wan-Li; Wang De-Zhen; Michael G. Kong

    2007-01-01

    The existence of two different discharge modes has been verified in an rf (radio-frequency) atmospheric pressure glow discharge (APGD) by Shi [J. Appl. Phys. 97, 023306 (2005)]. In the first mode, referred to as α mode, the discharge current density is relatively low and the bulk plasma electrons acquire the energy due to the sheath expansion.In the second mode, termed γ mode, the discharge current density is relatively high, the secondary electrons emitted by cathode under ion bombardment in the cathode sheath region play an important role in sustaining the discharge. In this paper, a one-dimensional self-consistent fluid model for rf APGDs is used to simulate the discharge mechanisms in the γmode in helium discharge between two parallel metallic planar electrodes. The results show that as the applied voltage increases, the discharge current becomes greater and the plasma density correspondingly increases, consequentially the discharge transits from the c mode into the γ mode. The high collisionality of the APGD plasma results in significant drop of discharge potential across the sheath region, and the electron Joule heating and the electron collisional energy loss reach their maxima in the region. The validity of the simulation is checked with the available experimental and numerical data.

  20. Array of surface-confined glow discharges in atmospheric pressure helium: Modes and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Liu, D. X., E-mail: liudingxin@gmail.com, E-mail: mglin5g@gmail.com [Center for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi (China); Nie, Q. Y.; Li, H. P. [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Chen, H. L. [Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Kong, M. G., E-mail: liudingxin@gmail.com, E-mail: mglin5g@gmail.com [Center for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi (China); Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2014-05-19

    Array of atmospheric pressure surface discharges confined by a two-dimensional hexagon electrode mesh is studied for its discharge modes and temporal evolution so as to a theoretical underpinning to their growing applications in medicine, aerodynamic control, and environmental remediation. Helium plasma surface-confined by one hexagon-shaped rim electrode is shown to evolve from a Townsend mode to a normal and abnormal glow mode, and its evolution develops from the rim electrodes as six individual microdischarges merging in the middle of the hexagon mesh element. Within one hexagon element, microdischarges remain largely static with the mesh electrode being the instantaneous cathode, but move towards the hexagon center when the electrode is the instantaneous anode. On the entire array electrode surface, plasma ignition is found to beat an unspecific hexagon element and then spreads to ignite surrounding hexagon elements. The spreading of microdischarges is in the form of an expanding circle at a speed of about 3 × 10{sup 4} m/s, and their quenching starts in the location of the initial plasma ignition. Plasma modes influence how input electrical power is used to generate and accelerate electrons and as such the reaction chemistry, whereas plasma dynamics are central to understand and control plasma instabilities. The present study provides an important aspect of plasma physics of the atmospheric surface-confined discharge array and a theoretical underpinning to its future technological innovation.

  1. Changes in the chemical reactivity of metals exposed to an inert gas glow discharge

    Energy Technology Data Exchange (ETDEWEB)

    Klemperer, D.F.; Williams, D.J. (Bristol Univ. (UK). Dept. of Physical Chemistry)

    1983-05-01

    From time to time the literature mentions curious effects on the chemical reactivity of metals due to inert gas ion bombardment: reactivity in corrosive environments is variously said to be inhibited or enhanced. Although there is no obvious explanation for such effects, some possible mechanisms have been suggested. Some simple experiments have been carried out to demonstrate that reactivity effects really do exist and to test such mechanisms. The results are qualitative because a glow discharge was used to implant the rare gas ions. Evaporated films of aluminium and nickel become amorphous after bombardment with xenon ions and the films resisted gaseous and liquid corrosion. On the other hand, aluminium foil bombarded with xenon ions in a Penning pump arrangement was attacked more heavily than unbombarded aluminium. Passivation is attributed to the known lack of reactivity of amorphous metals. Glassy materials appear to lack the normal routes of attack between their subsurface regions and the attacking medium. On the other hand, when a metal surface is heavily ion bombarded the surface is probably damaged to such an extent that the attacking medium gains physical access to the interior and corrosion proceeds rapidly.

  2. Photocatalytic Degradation of Methylene Blue with Side-glowing Optical Fiber Deliverying Visible Light

    Institute of Scientific and Technical Information of China (English)

    储金宇; 仲蕾

    2012-01-01

    The side-glowing optical fibers (SOFs) were chosen as the conducting medium of endogenous light; and 20 mg·L-1 methylene blue was chosen as the target to be degraded. The SOF is made up of quartz core with a silicon cladding, which can emit light through side surface more uniformly and transmit light for longer distance to avoid attenuation of light by liquid medium. The filament lamp was chosen as visible light source. Different reaction conditions, such as the presence of optical fiber or not, the quantity of SOF, light irradiation intensity were tested by measuring the methylene blue degradation of methylene blue. The results show that suitable reaction conditions were 1.167 g·L-1 Ag + /TiO 2 with 7% (by mass) of Ag + doped in TiO 2 , and 500 roots of SOF (30 cm length in solution). The photocatalytic degradation efficiency under 300W lamp irradiation for 8h was about 97%. And the photocatalytic degradation efficiency of methylene blue degradation was proportional to SOF quantity, light irradiation intensity and catalytic dosage within a certain range. Compared with general UV and visible light SOFs could save a huge amount of energy and cost, in the potential applications in dealing with organic pollutants on a large scale.

  3. Effects of rf power on chemical composition and surface roughness of glow discharge polymer films

    Science.gov (United States)

    Zhang, Ling; He, Xiaoshan; Chen, Guo; Wang, Tao; Tang, Yongjian; He, Zhibing

    2016-03-01

    The glow discharge polymer (GDP) films for laser fusion targets were successfully fabricated by plasma enhanced chemical vapor deposition (PECVD) at different radio frequency (rf) powers. The films were deposited using trans-2-butene (T2B) mixed with hydrogen as gas sources. The composition and state of plasma were diagnosed by quadrupole mass spectrometer (QMS) and Langmuir probe during the deposition process. The composition, surface morphology and roughness were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and white-light interferometer (WLI), respectively. Based on these observation and analyses, the growth mechanism of defects in GDP films were studied. The results show that, at low rf power, there is a larger probability for secondary polymerization and formation of multi-carbon C-H species in the plasma. In this case, the surface of GDP film turns to be cauliflower-like. With the increase of rf power, the degree of ionization is high, the relative concentration of smaller-mass hydrocarbon species increases, while the relative concentration of larger-mass hydrocarbon species decreases. At higher rf power, the energy of smaller-mass species are high and the etching effects are strong correspondingly. The GDP film's surface roughness shows a trend of decrease firstly and then increase with the increasing rf power. At rf power of 30 W, the surface root-mean-square roughness (Rq) drops to the lowest value of 12.8 nm, and no "void" defect was observed.

  4. Non-local effects in a stratified glow discharge with dust particles

    Energy Technology Data Exchange (ETDEWEB)

    Sukhinin, G I; Fedoseev, A V [Institute of Thermophysics SB RAS, Lavrentyev Ave., 1, Novosibirsk, 630090 (Russian Federation); Ramazanov, T S; Amangaliyeva, R Zh; Dosbalayev, M K; Jumabekov, A N [Institute of Experimental and Theoretical Physics, Al Farabi Kazakh National University, Tole Bi, 96a, Almaty, 050012 (Kazakhstan)], E-mail: fedoseev@itp.nsc.ru

    2008-12-21

    The work is aimed at describing non-local effects in the positive column of a low-pressure stratified dc glow discharge in argon with dust particles in a vertical cylindrical discharge tube. Numerical calculations of plasma parameters in the axis of the discharge tube were performed with the help of a hybrid model based on the solution of a non-local Boltzmann equation for electron energy distribution function (EEDF). Axial distributions of optical emission from striations with dust particles were measured experimentally. Negatively charged dust particles in a low-pressure stratified gas discharge should levitate at the anode-side branch of an electric field distribution above its maximum. At the same time the experiments showed that the dust particles levitate at the cathode side of a stratum. This paradox is explained by the fact that in a low-pressure striated discharge the optical emission distribution is displaced relative to the electric field distribution that was shown both by numerical simulations and experimental measurements.

  5. Destruction of 4-phenolsulfonic acid in water by anodic contact glow discharge electrolysis

    Institute of Scientific and Technical Information of China (English)

    Haiming Yang; Baigang An; Shaoyan Wang; Lixiang Li; Wenjie Jin; Lihua Li

    2013-01-01

    Destruction of 4-phenolsulfonic acid (4-PSA) in water was carried out using anodic contact glow discharge electrolysis.Accompanying the decay of 4-PSA,the amount of total organic carbon (TOC) in water correspondingly decreased,while the sulfonate group of 4-PSA was released as sulfate ion.Oxalate and formate were obtained as minor by-products.Additionally,phenol,1,4-hydroquinone,hydroxyquinol and 1,4-benzoquinone were detected as primary intermediates in the initial stages of decomposition of 4-PSA.A reaction pathway involving successive attacks of hydroxyl and hydrogen radicals was assumed on the basis of the observed products and kinetics.It was revealed that the decay of both 4-PSA and TOC obeyed a first-order rate law.The effects of different Fe ions and initial concentrations of 4-PSA on the degradation rate were investigated.It was found that the presence of Fe ions could increase the degradation rate of 4-PSA,while initial concentrations lower than 80 mmol/L had no significant effect on kinetic behaviour.The disappearance rate of 4-PSA was significantly affected by pH.

  6. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat [Department of Physics, Facuty of Science, Chulalongkorn University, Bangkok (Thailand); Plasma Technology and Nuclear Fusion Research Unit, Chulalongkorn University, Bangkok (Thailand)

    2015-04-24

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (T{sub e}) and electron number density (n{sub e}) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10{sup −17} − 10{sup −18} m{sup −3} where the electron temperature is between 1.00−2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  7. Liquid-phase reactions induced by atmospheric pressure glow discharge with liquid electrode

    Science.gov (United States)

    Tochikubo, Fumiyoshi; Shirai, Naoki; Uchida, Satoshi

    2014-12-01

    We experimentally investigated some of the initial reactions in a liquid induced by electron or positive-ion irradiation from an atmospheric-pressure dc glow discharge in contact with the liquid. We used an H-shaped glass reactor to observe the effects of electron irradiation and positive-ion irradiation on the liquid-phase reaction separately and simultaneously. Aqueous solutions of NaCl, AgNO3, HAuCl4, and FeCl2 are used as the electrolyte. Solutions of AgNO3 and HAuCl4 are used for the generation of Ag and Au nanoparticles, respectively. Solution of FeCl2 is used for the generation of ferromagnetic particles. Experimental results showed that electron irradiation of the liquid surface generates OH- in water and that positive-ion irradiation of the liquid surface generates H+ in water even without the dissolution of gas-phase nitrogen oxide. A possible reaction process is qualitatively discussed. We also showed that the control of reductive and oxidative environment in the liquid is possible not only by the gas composition for the plasma generation but also by the liquid composition.

  8. Surface Treatment of Polyethylene Terephthalate Film Using Atmospheric Pressure Glow Discharge in Air

    Institute of Scientific and Technical Information of China (English)

    方志; 邱毓昌; 王辉

    2004-01-01

    Non-thermal plasmas under atmospheric pressure are of great interest in polymer surface processing because of their convenience, effectiveness and low cost. In this paper, the treatment of Polyethylene terephthalate (PET) film surface for improving hydrophilicity using the non-thermal plasma generated by atmospheric pressure glow discharge (APGD) in air is conducted.The discharge characteristics of APGD are shown by measurement of their electrical discharge parameters and observation of light-emission phenomena, and the surface properties of PET before and after the APGD treatment are studied using contact angle measurement, x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It is found that the APGD is homogeneous and stable in the whole gas gap, which differs from the commonly filamentary dielectric barrier discharge (DBD). A short time (several seconds) APGD treatment can modify the surface characteristics of PET film markedly and uniformly. After 10 s APGD treatment, the surface oxygen content of PET surface increases to 39%, and the water contact angle decreases to 19°, respectively.

  9. Investigation of multifractal nature of floating potential fluctuations obtained from a dc glow discharge magnetized plasma

    Science.gov (United States)

    Shaw, Pankaj Kumar; Saha, Debajyoti; Ghosh, Sabuj; Janaki, M. S.; Iyengar, A. N. Sekar

    2017-03-01

    In this paper, multifractal detrended fluctuation analysis (MF-DFA) has been used to analyze the floating potential fluctuations obtained with a Langmuir probe from a dc glow discharge magnetized plasma device. The generalized Hurst exponents (h(q)) , local fluctuation function (Fq(s)) , the Rényi exponents (τ(q)) and the multifractal spectrum F(α) have been calculated by applying the MF-DFA method. The result of the MF-DFA shows the multifractal nature of these fluctuations. We have investigated the influence of magnetic field on the multifractal nature of the fluctuations and it is seen that degree of multifractality is reduced with the increase in the magnetic field strength. The values of h(q) have been restricted between 0.7 and 1 for the magnetized fluctuations. This result is evidence of the existence of long-range correlations in the fluctuations. Furthermore, we employed shuffle and surrogate approaches to analyze the origins of multifractality. Comparing the MF-DFA results for the data set to those for shuffled and surrogate series, we have found that its multifractal nature is due to the existence of significant long-term correlation.

  10. Laser-induced optogalvanic signal oscillations in miniature neon glow discharge plasma.

    Science.gov (United States)

    Saini, V K

    2013-06-20

    Laser-induced optogalvanic (OG) signal oscillations detected in miniature neon glow discharge plasma are investigated using a discharge equivalent-circuit model. The damped oscillations in OG signal are generated when a pulsed dye laser is tuned to a specific neon transition (1s5→2p2) at 588.2 nm under the discharge conditions where dynamic resistance changes its sign. Penning ionization via quasi-resonant energy transfer collisions between neon gas atoms in metastable state and sputtered electrode atoms in ground state is discussed to explain the negative differential resistance properties of discharge plasma that are attributed to oscillations in the OG signal. The experimentally observed results are simulated by analyzing the behavior of an equivalent discharge-OG circuit. Good agreement between theoretically calculated and experimental results is observed. It is found that discharge plasma is more sensitive and less stable in close vicinity to dynamic resistance sign inversion, which can be useful for weak-optical-transition OG detection.

  11. Tribological Properties of the Fe-Al-Cr Alloyed Layer by Double Glow Plasma Surface Metallurgy

    Science.gov (United States)

    Luo, Xixi; Yao, Zhengjun; Zhang, Pingze; Zhou, Keyin; Wang, Zhangzhong

    2016-09-01

    A Fe-Al-Cr alloyed layer was deposited onto the surface of Q235 low-carbon steel via double glow plasma surface metallurgy (DGPSM) to improve the steel's wear resistance. After the DGPSM treatment, the Fe-Al-Cr alloyed layer grown on the Q235 low-carbon steel was homogeneous and compact and had a thickness of 25 µm. The layer was found to be metallurgically adhered to the substrate. The frictional coefficient and specific wear rate of the sample with a Fe-Al-Cr alloyed layer (treated sample) were both lower than those of the bare substrate (untreated sample) at the measured temperatures (25, 250 and 450 °C). The results indicated that the substrate and the alloyed layer suffered oxidative wear and abrasive wear, respectively, and that the treated samples exhibited much better tribological properties than did the substrate. The formation of Fe2AlCr, Fe3Al(Cr), FeAl(Cr), Fe(Cr) sosoloid and Cr23C6 phases in the alloyed layer dramatically enhanced the wear resistance of the treated sample. In addition, the alloyed layer's oxidation film exhibited a self-healing capacity with lubrication action that also contributed to the improvement of the wear resistance at high temperature. In particular, at 450 °C, the specific wear rate of treated sample was 2.524 × 10-4 mm3/N m, which was only 45.2% of the untreated sample.

  12. Surface Modification of Asymmetric Polysulfone/Polyethylene Glycol Membranes by DC Ar-Glow Discharge Plasma

    Directory of Open Access Journals (Sweden)

    Chalad Yuenyao

    2016-01-01

    Full Text Available Polysulfone/polyethylene glycol (PSF/PEG membranes were prepared by dry/wet phase inversion method. Effects of direct current glow discharge plasma using argon as working gas on morphological structures and gas separation properties of membranes were studied. Alteration of membrane characteristics were analyzed by various techniques like contact angle, scanning electron microscope, Fourier transform infrared spectroscopy, and dynamic mechanical thermal analysis. Gas separation properties were measured in terms of permeation and ideal O2/N2 selectivity. Results showed that hydrophilic and gas separation properties of PSF/PEG membranes increased by plasma surface modification. It was also shown that the dosage of PEG and plasma treatment affected the morphological structures and mechanical and gas separation properties. The macro voids and transmembrane structure disappeared with a little amount of PEG dosage. Pore size and mechanical strength tend to decrease with increasing PEG dosage up to 10 wt%. Glass transition temperature (Tg receded from 201.8 to 143.7°C for pure PSF and PSF/PEG with PEG dosage of 10 wt%. O2 and N2 gases permeation through the 10-minute plasma treated membranes tend to increase. However, the permeation strongly dispersed when treatment time was more extended.

  13. Achieving ultrahigh vacuum in an unbaked chamber with glow discharge conditioning

    Indian Academy of Sciences (India)

    ZIAUDDIN KHAN; PRATIBHA SEMWAL; KALPESH R DHANANI; DILIP C RAVAL; SUBRATA PRADHAN

    2017-01-01

    Glow discharge conditioning (GDC) has long been accepted as one of the basic wall conditioning techniques for achieving ultrahigh vacuum in an unbaked chamber. As a part of this fundamental experimental study, a test chamber has been fabricated from stainless steel 304 L with its inner surface electropolished on which a detailed investigation has been carried out. Both helium and hydrogen gases have been employed as discharge cleaning medium. The discharge cleaning was carried out at 0.1 A/m$^{2}$ current density with workingpressure maintained at $1.0 \\times 10^{−2}$ mbar. It was experimentally observed that the pump-down time to attain the base pressure $∼10−8$ mbar was reduced by 62% compared to the unbaked chamber being pumped to this ultimate vacuum. The results were similar irrespective of whether the discharge cleaning medium is either hydrogen or helium. It was also experimentally established that a better ultimate vacuum could be achieved as compared to theoretically calculated ultimate vacuum with the help of discharge cleaning.

  14. Electric field development in γ-mode radiofrequency atmospheric pressure glow discharge in helium

    Science.gov (United States)

    Navrátil, Zdeněk; Josepson, Raavo; Cvetanović, Nikola; Obradović, Bratislav; Dvořák, Pavel

    2016-06-01

    Time development of electric field strength during radio-frequency sheath formation was measured using Stark polarization spectroscopy in a helium γ-mode radio-frequency (RF, 13.56 MHz) atmospheric pressure glow discharge at high current density (3 A cm-2). A method of time-correlated single photon counting was applied to record the temporal development of spectral profile of He I 492.2 nm line with a sub-nanosecond temporal resolution. By fitting the measured profile of the line with a combination of pseudo-Voigt profiles for forbidden (2 1P-4 1F) and allowed (2 1P-4 1D) helium lines, instantaneous electric fields up to 32 kV cm-1 were measured in the RF sheath. The measured electric field is in agreement with the spatially averaged value of 40 kV cm-1 estimated from homogeneous charge density RF sheath model. The observed rectangular waveform of the electric field time development is attributed to increased sheath conductivity by the strong electron avalanches occurring in the γ-mode sheath at high current densities.

  15. Abnormal glow discharge as a variable capacitor for tunable RF systems

    Science.gov (United States)

    Macheret, Sergey; Semnani, Abbas; Peroulis, Dimitrios

    2016-09-01

    For frequency-tunable resonators and filters in high-power applications, conventional semiconductor devices are easily damaged, while mechanically-tunable systems are bulky and slow. In this regard, weakly ionized plasmas can offer an attractive solution. In this work, an LC resonator circuit where a commercial gas discharge tube (GDT) serves as a variable capacitor was studied experimentally and theoretically. The experiments show continuous decrease of the resonant frequency by up to 50 percent with increase in the DC current through the GDT. Analysis of the current-voltage characteristic and the breakdown parameters, combined with lumped-parameter equivalent-circuit RF simulations, allowed us to determine the gas pressure, the electrode coating material and the secondary emission coefficient, and to achieve a very good agreement between the calculated and measured transmittance values. The analysis reveals that reduction in the cathode sheath thickness with increase in the DC current in the abnormal glow discharge regime is the key factor responsible for the experimentally observed tunability.

  16. Two-dimensional modeling of a glow discharge source for mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Fiala, A.; Pitchford, L.C.; Boeuf, J.P. [Univ. Paul Sabatier, Toulouse (France); Baude, S. [CEA, Bruyeres-le-Chatel (France); Blaise, G. [Univ. Paris 11, Orsay (France). Lab. de Physique des Solides

    1996-12-31

    Glow discharge mass spectrometry (GDMS) is now widely used for elemental analysis of various materials. This diagnostic uses a low current discharge in a buffer gas to sputter atoms from a sample to be analyzed. A small density of atoms of the sample are thus introduced into the gas phase. These atoms are ionized in the discharge, and the ions are extracted through a small, rectangular slit leading to a mass spectrometer. Very low absolute detection limits are possible with GDMS`s, but many aspects of this diagnostic still require careful adjustments to achieve good performance. A better understanding especially of the influence of the discharge operating conditions (pressure, current, geometry,...) on the ion fluxes arriving at the plane of the exit slit is needed. The purpose of the work presented here is to develop such an understanding through a combined experimental and theoretical program, but the work reported here relates mainly to results from the model. The particular conditions the authors have chosen to study correspond to the commercially available VG9000 spectrometer and Megacell source.

  17. The breakdown and glow phases during the initiation of discharges for lamps

    Energy Technology Data Exchange (ETDEWEB)

    Pitchford, L.C.; Peres, I.; Liland, K.B.; Boeuf, J.P. [Centre de Physique des Plasmas et Applications, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse (France); Gielen, H. [Central Development Laboratories, Philips Lighting, Eindhoven (The Netherlands)

    1997-07-01

    High intensity discharge (HID) lamps are often initiated by the application of one or more short, high-voltage, breakdown pulses superimposed on a 50 or 60 Hz generator voltage. A successful transition from the breakdown event to steady-state operating conditions in HID lamps requires that the lamp-circuit system be adequate to sustain the plasma created during breakdown until the electrodes are heated to thermionic temperatures. In this article, we use a one-dimensional (in the axial direction) transient discharge model to study the conditions needed to sustain the cold-cathode discharge after a breakdown event has occurred. While the application of our one-dimensional model to real lamps is approximate, we find that the model predictions are consistent with experimental results in HID lamps, a few of which are presented here. The main conclusion from this work is that, after breakdown, the voltage necessary to sustain a glow discharge is dependent on the source impedance, the gas composition, and on the plasma density created by the breakdown event. {copyright} {ital 1997 American Institute of Physics.}

  18. Auxiliary glow discharge in the trigger unit of a hollow-cathode thyratron

    Science.gov (United States)

    Korolev, Yu. D.; Landl, N. V.; Geyman, V. G.; Frants, O. B.; Shemyakin, I. A.; Nekhoroshev, V. O.

    2016-08-01

    Results from studies of a low-current glow discharge with a hollow cathode are presented. A specific feature of the discharge conditions was that a highly emissive tablet containing cesium carbonate was placed in the cathode cavity. In the absence of a tablet, the discharge ignition voltage was typically ≥3.5 kV, while the burning voltage was in the range of 500-600 V. The use of the tablet made it possible to decrease the ignition voltage to 280 V and maintain the discharge burning voltage at a level of about 130 V. A model of the current sustainment in a hollow-cathode discharge is proposed. Instead of the conventional secondary emission yield, the model uses a generalized emission yield that takes into account not only ion bombardment of the cathode, but also the emission current from an external source. The model is used to interpret the observed current-voltage characteristics. The results of calculations agree well with the experimental data. It is shown that, in some discharge modes, the external emission current from the cathode can reach 25% of the total discharge current.

  19. High frequency glow discharges at atmospheric pressure with micro-structured electrode arrays

    Science.gov (United States)

    Baars-Hibbe, L.; Sichler, P.; Schrader, C.; Lucas, N.; Gericke, K.-H.; Büttgenbach, S.

    2005-02-01

    Micro-structured electrode (MSE) arrays allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode widths, thicknesses and distances in the micrometre range are realized by means of modern micro-machining and galvanic techniques. The electrode distance, the gap width d, is small enough to generate sufficiently high electric field strengths to ignite gas discharges by applying only moderate radio frequency (RF, 13.56 MHz) voltages (80-390 V in Ne, He, Ar, N2 and air). The non-thermal plasma system is characterized by a special probe measuring the electric parameters. We tested MSE arrays with d = 70, 25 and 15 µm. The MSE driven plasmas show a different behaviour from conventional RF discharge plasmas. Due to the very small electrode gap width we can describe the behaviour of the charged particles in the RF field of our system with the dc Townsend breakdown theory, depending on the pressure range and gas. With decreasing pressure, the gas discharges, especially in Ne and He, are increasingly dominated by field electron emission. With the MSE arrays as plasma sources several applications were developed and successfully tested, e.g. decomposition of waste gases and sterilization of food packaging materials at atmospheric pressure.

  20. Study of a contracted glow in low-frequency plasma-jet discharges operating with argon

    Energy Technology Data Exchange (ETDEWEB)

    Minotti, F.; Giuliani, L.; Xaubet, M.; Grondona, D. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EHA, Buenos Aires, Argentina and Instituto de Física del Plasma (INFIP), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires - UBA, C1428EHA, Buenos Aires (Argentina)

    2015-11-15

    In this work, we present an experimental and theoretical study of a low frequency, atmospheric plasma-jet discharge in argon. The discharge has the characteristics of a contracted glow with a current channel of submillimeter diameter and a relatively high voltage cathode layer. In order to interpret the measurements, we consider the separate modeling of each region of the discharge: main channel and cathode layer, which must then be properly matched together. The main current channel was modeled, extending a previous work, as similar to an arc in which joule heating is balanced by lateral heat conduction, without thermal equilibrium between electrons and heavy species. The cathode layer model, on the other hand, includes the emission of secondary electrons by ion impact and by additional mechanisms, of which we considered emission due to collision of atoms excited at metastable levels, and field-enhanced thermionic emission (Schottky effect). The comparison of model and experiment indicates that the discharge can be effectively sustained in its contracted form by the secondary electrons emitted by collision of excited argon atoms, whereas thermionic emission is by far insufficient to provide the necessary electrons.