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Sample records for bubr1 kinetochore interactions

  1. The architecture of the BubR1 tetratricopeptide tandem repeat defines a protein motif underlying mitotic checkpoint-kinetochore communication

    DEFF Research Database (Denmark)

    Bolanos-Garcia, Victor M; Nilsson, Jakob; Blundell, Tom L

    2012-01-01

    advance to anaphase before every chromosome is properly attached to microtubules of the mitotic spindle. The architecture of the KNL1-BubR1 complex reveals important features of the molecular recognition between SAC components and the kinetochore. The interaction is important for a functional SAC...... as substitution of BubR1 residues engaged in KNL1 binding impaired the SAC and BubR1 recruitment into checkpoint complexes in stable cell lines. Here we discuss the implications of the disorder-to-order transition of KNL1 upon BubR1 binding for SAC signaling and propose a mechanistic model of how BUBs binding may...

  2. Distinct domains in Bub1 localize RZZ and BubR1 to kinetochores to regulate the checkpoint

    DEFF Research Database (Denmark)

    Zhang, Gang; Lischetti, Tiziana; Hayward, Daniel G;

    2015-01-01

    , we show that a distinct region in Bub1 mediates kinetochore localization of BubR1 through direct binding, but surprisingly removal of this region increases checkpoint strength. Our work thus uncovers how Bub1 coordinates checkpoint signalling by distinct domains for RZZ and BubR1 recruitment...

  3. Structure of a Blinkin-BUBR1 complex reveals an interaction crucial for kinetochore-mitotic checkpoint regulation via an unanticipated binding Site

    DEFF Research Database (Denmark)

    Bolanos-Garcia, Victor M; Lischetti, Tiziana; Matak-Vinković, Dijana

    2011-01-01

    The maintenance of genomic stability relies on the spindle assembly checkpoint (SAC), which ensures accurate chromosome segregation by delaying the onset of anaphase until all chromosomes are properly bioriented and attached to the mitotic spindle. BUB1 and BUBR1 kinases are central for this proc...

  4. The architecture of the BubR1 tetratricopeptide tandem repeat defines a protein motif underlying mitotic checkpoint-kinetochore communication.

    Science.gov (United States)

    Bolanos-Garcia, Victor M; Nilsson, Jakob; Blundell, Tom L

    2012-01-01

    The accurate and timely transmission of the genetic material to progeny during successive rounds of cell division is sine qua non for the maintenance of genome stability. Eukaryotic cells have evolved a surveillance mechanism, the mitotic spindle assembly checkpoint (SAC), to prevent premature advance to anaphase before every chromosome is properly attached to microtubules of the mitotic spindle. The architecture of the KNL1-BubR1 complex reveals important features of the molecular recognition between SAC components and the kinetochore. The interaction is important for a functional SAC as substitution of BubR1 residues engaged in KNL1 binding impaired the SAC and BubR1 recruitment into checkpoint complexes in stable cell lines. Here we discuss the implications of the disorder-to-order transition of KNL1 upon BubR1 binding for SAC signaling and propose a mechanistic model of how BUBs binding may affect the recognition of KNL1 by its other interacting partners.

  5. Drosophila CENP-A mutations cause a BubR1-dependent early mitotic delay without normal localization of kinetochore components.

    Directory of Open Access Journals (Sweden)

    Michael D Blower

    2006-07-01

    Full Text Available The centromere/kinetochore complex plays an essential role in cell and organismal viability by ensuring chromosome movements during mitosis and meiosis. The kinetochore also mediates the spindle attachment checkpoint (SAC, which delays anaphase initiation until all chromosomes have achieved bipolar attachment of kinetochores to the mitotic spindle. CENP-A proteins are centromere-specific chromatin components that provide both a structural and a functional foundation for kinetochore formation. Here we show that cells in Drosophila embryos homozygous for null mutations in CENP-A (CID display an early mitotic delay. This mitotic delay is not suppressed by inactivation of the DNA damage checkpoint and is unlikely to be the result of DNA damage. Surprisingly, mutation of the SAC component BUBR1 partially suppresses this mitotic delay. Furthermore, cid mutants retain an intact SAC response to spindle disruption despite the inability of many kinetochore proteins, including SAC components, to target to kinetochores. We propose that SAC components are able to monitor spindle assembly and inhibit cell cycle progression in the absence of sustained kinetochore localization.

  6. Direct binding between BubR1 and B56-PP2A phosphatase complexes regulate mitotic progression

    DEFF Research Database (Denmark)

    Kruse, Thomas; Zhang, Gang; Larsen, Marie Sofie Yoo;

    2013-01-01

    and mutation of these residues prevents the establishment of a proper metaphase plate and delays cells in mitosis. Furthermore, we show that phosphorylation of S670 and S676 stimulates the binding of B56 to BubR1 and that BubR1 targets a pool of B56 to kinetochores. Our data suggests that BubR1 counteracts...

  7. Protein kinase TTK interacts and co-localizes with CENP-E to the kinetochore of human cells

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Spindle checkpoint is an important biochemical signaling cascade during mitosis which monitors the fidelity of chromosome segregation, and is mediated by protein kinases Mps1 and Bub1/BubR1. Our recent studies show that kinesin-related motor protein CENP-E interacts with BubR1 and participates in spindle checkpoint signaling. To elucidate the molecular mechanisms underlying spindle checkpoint signaling, we carried out proteomic dissection of human cell kinetochore and revealed protein kinase TTK, human homologue of yeast Mps1. Our studies show that TTK is localized to the kinetochore of human cells, and interacts with CENP-E, suggesting that TTK may play an important role in chromosome segregation during mitosis.

  8. The internal Cdc20 binding site in BubR1 facilitates both spindle assembly checkpoint signalling and silencing

    DEFF Research Database (Denmark)

    Lischetti, Tiziana; Zhang, Gang; Sedgwick, Garry G;

    2014-01-01

    Improperly attached kinetochores activate the spindle assembly checkpoint (SAC) and by an unknown mechanism catalyse the binding of two checkpoint proteins, Mad2 and BubR1, to Cdc20 forming the mitotic checkpoint complex (MCC). Here, to address the functional role of Cdc20 kinetochore localization...... on the SAC because the IC20BD is also required for efficient SAC silencing. Indeed, the IC20BD can disrupt the MCC providing a mechanism for its role in SAC silencing. We thus uncover an unexpected dual function of the second Cdc20 binding site in BubR1 in promoting both efficient SAC signalling and SAC...

  9. Usp16 regulates kinetochore localization of Plk1 to promote proper chromosome alignment in mitosis.

    Science.gov (United States)

    Zhuo, Xiaolong; Guo, Xiao; Zhang, Xiaoyan; Jing, Guihua; Wang, Yao; Chen, Qiang; Jiang, Qing; Liu, Junjun; Zhang, Chuanmao

    2015-08-31

    During the G2 to M phase transition, a portion of mitotic regulator Plk1 localizes to the kinetochores and regulates the initiation of kinetochore-microtubule attachments for proper chromosome alignment. Once kinetochore-microtubule attachment is achieved, this portion of Plk1 is removed from the kinetochores as a result of ubiquitination. However, the crucial molecular mechanism that promotes the localization and the maintenance of Plk1 on the kinetochores until metaphase is still unclear. We report that ubiquitin-specific peptidase 16 (Usp16) plays a key role during this process. Usp16 deubiquitinates Plk1, resulting in an enhanced interaction with kinetochore-localized proteins such as BubR1, and thereby retains Plk1 on the kinetochores to promote proper chromosome alignment in early mitosis. Down-regulation of Usp16 causes increased ubiquitination and decreased kinetochore localization of Plk1. Thus, our data unveil a unique mechanism by which Usp16 promotes the localization and maintenance of Plk1 on the kinetochores for proper chromosome alignment.

  10. Kinetochore-Dependent Microtubule Rescue Ensures Their Efficient and Sustained Interactions in Early Mitosis

    Science.gov (United States)

    Gandhi, Sapan R.; Gierliński, Marek; Mino, Akihisa; Tanaka, Kozo; Kitamura, Etsushi; Clayton, Lesley; Tanaka, Tomoyuki U.

    2011-01-01

    Summary How kinetochores regulate microtubule dynamics to ensure proper kinetochore-microtubule interactions is unknown. Here, we studied this during early mitosis in Saccharomyces cerevisiae. When a microtubule shrinks and its plus end reaches a kinetochore bound to its lateral surface, the microtubule end attempts to tether the kinetochore. This process often fails and, responding to this failure, microtubule rescue (conversion from shrinkage to growth) occurs, preventing kinetochore detachment from the microtubule end. This rescue is promoted by Stu2 transfer (ortholog of vertebrate XMAP215/ch-TOG) from the kinetochore to the microtubule end. Meanwhile, microtubule rescue distal to the kinetochore is also promoted by Stu2, which is transported by a kinesin-8 motor Kip3 along the microtubule from the kinetochore. Microtubule extension following rescue facilitates interaction with other widely scattered kinetochores, diminishing long delays in collecting the complete set of kinetochores by microtubules. Thus, kinetochore-dependent microtubule rescue ensures efficient and sustained kinetochore-microtubule interactions in early mitosis. PMID:22075150

  11. Bub3-BubR1-dependent sequestration of Cdc20Fizzy at DNA breaks facilitates the correct segregation of broken chromosomes.

    Science.gov (United States)

    Derive, Nicolas; Landmann, Cedric; Montembault, Emilie; Claverie, Marie-Charlotte; Pierre-Elies, Priscillia; Goutte-Gattat, Damien; Founounou, Nabila; McCusker, Derek; Royou, Anne

    2015-11-09

    The presence of DNA double-strand breaks during mitosis is particularly challenging for the cell, as it produces broken chromosomes lacking a centromere. This situation can cause genomic instability resulting from improper segregation of the broken fragments into daughter cells. We recently uncovered a process by which broken chromosomes are faithfully transmitted via the BubR1-dependent tethering of the two broken chromosome ends. However, the mechanisms underlying BubR1 recruitment and function on broken chromosomes were largely unknown. We show that BubR1 requires interaction with Bub3 to localize on the broken chromosome fragments and to mediate their proper segregation. We also find that Cdc20, a cofactor of the E3 ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C), accumulates on DNA breaks in a BubR1 KEN box-dependent manner. A biosensor for APC/C activity demonstrates a BubR1-dependent local inhibition of APC/C around the segregating broken chromosome. We therefore propose that the Bub3-BubR1 complex on broken DNA inhibits the APC/C locally via the sequestration of Cdc20, thus promoting proper transmission of broken chromosomes.

  12. BubR1 is modified by sumoylation during mitotic progression.

    Science.gov (United States)

    Yang, Feikun; Hu, Liyan; Chen, Cheng; Yu, Jianxiu; O'Connell, Christopher B; Khodjakov, Alexey; Pagano, Michele; Dai, Wei

    2012-02-10

    BubR1 functions as a crucial component that monitors proper chromosome congression and mitotic timing during cell division. We investigated molecular regulation of BubR1 and found that BubR1 was modified by an unknown post-translation mechanism during the cell cycle, resulting in a significant mobility shift on denaturing gels. We termed it BubR1-M as the nature of modification was not characterized. Extended (>24 h) treatment of HeLa cells with a microtubule disrupting agent including nocodazole and taxol or release of mitotic shake-off cells into fresh medium induced BubR1-M. BubR1-M was derived from neither phosphorylation nor acetylation. Ectopic expression coupled with pulling down analyses showed that BubR1-M was derived from SUMO modification. Mutation analysis revealed that lysine 250 was a crucial site for sumoylation. Significantly, compared with the wild-type control, ectopic expression of a sumoylation-deficient mutant of BubR1 induced chromosomal missegregation and mitotic delay. Combined, our study identifies a new type of post-translational modification that is essential for BubR1 function during mitosis.

  13. In vitro kinetochore assembly

    Science.gov (United States)

    Miell, Matthew D D; Straight, Aaron F

    2016-01-01

    The kinetochore is the primary site of interaction between chromosomes and microtubules of the mitotic spindle during chromosome segregation. The kinetochore is a complex of more than 100 proteins that transiently assemble during mitosis at a single defined region on each chromosome, known as the centromere. Kinetochore assembly and activity must be tightly regulated to ensure proper microtubule interaction and faithful chromosome segregation because perturbation of kinetochores often results in aneuploidy and cell lethality. As such, cell free and reconstituted systems to analyze kinetochore formation and function are invaluable in probing the biochemical activities of kinetochores. In vitro approaches to studying kinetochores have enabled the manipulation of kinetochore protein structure, function, interactions and regulation that are not possible in cells. Here we outline a cell-free approach for the assembly of centromeres and recruitment of functional kinetochores that enables their manipulation and analysis. PMID:27193846

  14. Meiosis I chromosome segregation is established through regulation of microtubule-kinetochore interactions.

    Science.gov (United States)

    Miller, Matthew P; Unal, Elçin; Brar, Gloria A; Amon, Angelika

    2012-12-18

    During meiosis, a single round of DNA replication is followed by two consecutive rounds of nuclear divisions called meiosis I and meiosis II. In meiosis I, homologous chromosomes segregate, while sister chromatids remain together. Determining how this unusual chromosome segregation behavior is established is central to understanding germ cell development. Here we show that preventing microtubule-kinetochore interactions during premeiotic S phase and prophase I is essential for establishing the meiosis I chromosome segregation pattern. Premature interactions of kinetochores with microtubules transform meiosis I into a mitosis-like division by disrupting two key meiosis I events: coorientation of sister kinetochores and protection of centromeric cohesin removal from chromosomes. Furthermore we find that restricting outer kinetochore assembly contributes to preventing premature engagement of microtubules with kinetochores. We propose that inhibition of microtubule-kinetochore interactions during premeiotic S phase and prophase I is central to establishing the unique meiosis I chromosome segregation pattern.DOI:http://dx.doi.org/10.7554/eLife.00117.001.

  15. Kinetochore-microtubule error correction is driven by differentially regulated interaction modes.

    Science.gov (United States)

    Kalantzaki, Maria; Kitamura, Etsushi; Zhang, Tongli; Mino, Akihisa; Novák, Béla; Tanaka, Tomoyuki U

    2015-04-01

    For proper chromosome segregation, sister kinetochores must interact with microtubules from opposite spindle poles (bi-orientation). To establish bi-orientation, aberrant kinetochore-microtubule attachments are disrupted (error correction) by aurora B kinase (Ipl1 in budding yeast). Paradoxically, during this disruption, new attachments are still formed efficiently to enable fresh attempts at bi-orientation. How this is possible remains an enigma. Here we show that kinetochore attachment to the microtubule lattice (lateral attachment) is impervious to aurora B regulation, but attachment to the microtubule plus end (end-on attachment) is disrupted by this kinase. Thus, a new lateral attachment is formed without interference, then converted to end-on attachment and released if incorrect. This process continues until bi-orientation is established and stabilized by tension across sister kinetochores. We reveal how aurora B specifically promotes disruption of the end-on attachment through phospho-regulation of kinetochore components Dam1 and Ndc80. Our results reveal fundamental mechanisms for promoting error correction for bi-orientation.

  16. Tumor suppressor protein DAB2IP participates in chromosomal stability maintenance through activating spindle assembly checkpoint and stabilizing kinetochore-microtubule attachments

    Science.gov (United States)

    Yu, Lan; Shang, Zeng-Fu; Abdisalaam, Salim; Lee, Kyung-Jong; Gupta, Arun; Hsieh, Jer-Tsong; Asaithamby, Aroumougame; Chen, Benjamin P.C.; Saha, Debabrata

    2016-01-01

    Defects in kinetochore-microtubule (KT-MT) attachment and the spindle assembly checkpoint (SAC) during cell division are strongly associated with chromosomal instability (CIN). CIN has been linked to carcinogenesis, metastasis, poor prognosis and resistance to cancer therapy. We previously reported that the DAB2IP is a tumor suppressor, and that loss of DAB2IP is often detected in advanced prostate cancer (PCa) and is indicative of poor prognosis. Here, we report that the loss of DAB2IP results in impaired KT-MT attachment, compromised SAC and aberrant chromosomal segregation. We discovered that DAB2IP directly interacts with Plk1 and its loss inhibits Plk1 kinase activity, thereby impairing Plk1-mediated BubR1 phosphorylation. Loss of DAB2IP decreases the localization of BubR1 at the kinetochore during mitosis progression. In addition, the reconstitution of DAB2IP enhances the sensitivity of PCa cells to microtubule stabilizing drugs (paclitaxel, docetaxel) and Plk1 inhibitor (BI2536). Our findings demonstrate a novel function of DAB2IP in the maintenance of KT-MT structure and SAC regulation during mitosis which is essential for chromosomal stability. PMID:27568005

  17. The coordination of centromere replication, spindle formation, and kinetochore-microtubule interaction in budding yeast.

    Directory of Open Access Journals (Sweden)

    Hong Liu

    2008-11-01

    Full Text Available The kinetochore is a protein complex that assembles on centromeric DNA to mediate chromosome-microtubule interaction. Most eukaryotic cells form the spindle and establish kinetochore-microtubule interaction during mitosis, but budding yeast cells finish these processes in S-phase. It has long been noticed that the S-phase spindle in budding yeast is shorter than that in metaphase, but the biological significance of this short S-phase spindle structure remains unclear. We addressed this issue by using ask1-3, a temperature-sensitive kinetochore mutant that exhibits partially elongated spindles at permissive temperature in the presence of hydroxyurea (HU, a DNA synthesis inhibitor. After exposure to and removal of HU, ask1-3 cells show a delayed anaphase entry. This delay depends on the spindle checkpoint, which monitors kinetochore-microtubule interaction defects. Overproduction of microtubule-associated protein Ase1 or Cin8 also induces spindle elongation in HU-arrested cells. The spindle checkpoint-dependent anaphase entry delay is also observed after ASE1 or CIN8 overexpression in HU-arrested cells. Therefore, the shorter spindle in S-phase cells is likely to facilitate proper chromosome-microtubule interaction.

  18. Elevated BUBR1 expression is associated with poor survival in early breast cancer patients: 15-year follow-up analysis.

    Science.gov (United States)

    Maciejczyk, Adam; Szelachowska, Jolanta; Czapiga, Bogdan; Matkowski, Rafał; Hałoń, Agnieszka; Györffy, Balázs; Surowiak, Paweł

    2013-05-01

    BUBR1 (budding uninhibited by benzimidazole-related 1) represents the component of a controlling complex in mitosis. Defects in mitotic control complex result in chromosomal instability and, as a result, disturb the mitotic process. This study was aimed at examining the prognostic value linked to the expression of BUBR1 in a group of patients with breast cancer. We analyzed the expression of BUBR1 in 98 stage II breast cancer patients with a median follow-up of 15 years. Immunohistochemical reactions were performed using monoclonal antibodies against BUBR1. We also studied the prognostic value of BUBR1 mRNA expression using the Kaplan-Meier (KM) plotter, which assessed the effect of 22,277 genes on survival in 2422 breast cancer patients. A background database was established using gene expression data and survival information on 2422 patients downloaded from the Gene Expression Omnibus (GEO; Affymetrix HGU133A and HGU133+2 microarrays). The median relapse-free survival was 6.43 years. Univariate and multivariate analyses showed that higher expression of BUBR1 was typical for cases of shorter overall survival, disease-free time, and disease-specific survival. KM plotter analysis showed that elevated BUBR1 mRNA expression had a negative impact on patients' relapse-free, distant metastases-free, and overall survival. Elevated BUBR1 expression was associated with poor survival in early stage breast cancer patients.

  19. The role of BUBR1 in the maintenance of chromosomal stability

    NARCIS (Netherlands)

    Suijkerbuijk, S.J.E.

    2012-01-01

    The majority of solid tumours contain an incorrect number of chromosomes. This state, called aneuploidy, can be caused by defects in chromosome segregation during the division of cells. Prevention against aneuploidy is dependent on BUBR1. This protein is an essential component of a surveillance mech

  20. Deacetylation of the mitotic checkpoint protein BubR1 at lysine 250 by SIRT2 and subsequent effects on BubR1 degradation during the prometaphase/anaphase transition.

    Science.gov (United States)

    Suematsu, Tomohisa; Li, Yanze; Kojima, Hirotada; Nakajima, Koichi; Oshimura, Mitsuo; Inoue, Toshiaki

    2014-10-24

    Mitotic catastrophe, a form of cell death that occurs during mitosis and after mitotic slippage to a tetraploid state, plays an important role in the efficacy of cancer cell killing by microtubule inhibitors. Prolonged mitotic arrest at the spindle assembly checkpoint (SAC) is a well-known requirement for mitotic catastrophe and, thus, for conferring sensitivity to microtubule inhibitors. We previously reported that downregulation of SIRT2, a member of the sirtuin family of NAD+-dependent deacetylases, confers resistance to microtubule inhibitors by abnormally prolonging mitotic arrest and thus compromising the cell death pathway after mitotic slippage. Thus, turning off SAC activation after a defined period is an additional requirement for efficient post-slippage death. Here, we investigated whether SIRT2 deacetylates BubR1, which is a core component of the SAC; acetylation of BubR1 at lysine 250 (K250) during prometaphase inhibits its APC/C-dependent proteolysis and thus regulates timing in anaphase entry. We showed that SIRT2 deacetylates BubR1 K250 both in vitro and in vivo. We also found that SIRT2 knockdown leads to increased levels of BubR1 acetylation at prometaphase; however, this increase is not substantial to elevate the levels of total BubR1 or delay the transition from prometaphase to anaphase. The present study shows that SIRT2 is a deacetylase for BubR1 K250, although the abnormally prolonged SAC activation observed in SIRT2 knockdown cells is not accompanied by a change in BubR1 levels or by delayed progression from prometaphase to anaphase.

  1. BubR1 Acts as a Promoter in Cellular Motility of Human Oral Squamous Cancer Cells through Regulating MMP-2 and MMP-9

    Directory of Open Access Journals (Sweden)

    Chou-Kit Chou

    2015-07-01

    Full Text Available BubR1 is a critical component of spindle assembly checkpoint, ensuring proper chromatin segregation during mitosis. Recent studies showed that BubR1 was overexpressed in many cancer cells, including oral squamous cell carcinomas (OSCC. However, the effect of BubR1 on metastasis of OSCC remains unclear. This study aimed to unravel the role of BubR1 in the progression of OSCC and confirm the expression of BubR1 in a panel of malignant OSCC cell lines with different invasive abilities. The results of quantitative real-time PCR showed that the mRNA level of BubR1 was markedly increased in four OSCC cell lines, Ca9-22, HSC3, SCC9 and Cal-27 cells, compared to two normal cells, normal human oral keratinocytes (HOK and human gingival fibroblasts (HGF. Moreover, the expression of BubR1 in these four OSCC cell lines was positively correlated with their motility. Immunofluorescence revealed that BubR1 was mostly localized in the cytosol of human gingival carcinoma Ca9-22 cells. BubR1 knockdown significantly decreased cellular invasion but slightly affect cellular proliferation on both Ca9-22 and Cal-27 cells. Consistently, the activities of metastasis-associated metalloproteinases MMP-2 and MMP-9 were attenuated in BubR1 knockdown Ca9-22 cells, suggesting the role of BubR1 in promotion of OSCC migration. Our present study defines an alternative pathway in promoting metastasis of OSCC cells, and the expression of BubR1 could be a prognostic index in OSCC patients.

  2. Mechanics of kinetochore microtubules and their interactions with chromosomes during cell division

    Science.gov (United States)

    Nazockdast, Ehssan; Fürthauer, Sebastian; Redemann, Stephanie; Baumgart, Johannes; Lindow, Norbert; Kratz, Andrea; Prohaska, Steffen; Müller-Reichert, Thomas; Shelley, Michael

    2016-11-01

    The accurate segregation of chromosomes, and subsequent cell division, in Eukaryotic cells is achieved by the interactions of an assembly of microtubules (MTs) and motor-proteins, known as the mitotic spindle. We use a combination of our computational platform for simulating cytoskeletal assemblies and our structural data from high-resolution electron tomography of the mitotic spindle, to study the kinetics and mechanics of MTs in the spindle, and their interactions with chromosomes during chromosome segregation in the first cell division in C.elegans embryo. We focus on kinetochore MTs, or KMTs, which have one end attached to a chromosome. KMTs are thought to be a key mechanical component in chromosome segregation. Using exploratory simulations of MT growth, bending, hydrodynamic interactions, and attachment to chromosomes, we propose a mechanical model for KMT-chromosome interactions that reproduces observed KMT length and shape distributions from electron tomography. We find that including detailed hydrodynamic interactions between KMTs is essential for agreement with the experimental observations.

  3. Mouse oocytes depend on BubR1 for proper chromosome segregation but not for prophase I arrest

    NARCIS (Netherlands)

    Touati, S.A.; Buffin, E.; Cladiere, D.; Hached, K.; Rachez, C.; Deursen, J.M.A. van; Wassmann, K.

    2015-01-01

    Mammalian female meiosis is error prone, with rates of meiotic chromosome missegregations strongly increasing towards the end of the reproductive lifespan. A strong reduction of BubR1 has been observed in oocytes of women approaching menopause and in ovaries of aged mice, which led to the hypothesis

  4. Adaptive changes in the kinetochore architecture facilitate proper spindle assembly.

    Science.gov (United States)

    Magidson, Valentin; Paul, Raja; Yang, Nachen; Ault, Jeffrey G; O'Connell, Christopher B; Tikhonenko, Irina; McEwen, Bruce F; Mogilner, Alex; Khodjakov, Alexey

    2015-09-01

    Mitotic spindle formation relies on the stochastic capture of microtubules at kinetochores. Kinetochore architecture affects the efficiency and fidelity of this process with large kinetochores expected to accelerate assembly at the expense of accuracy, and smaller kinetochores to suppress errors at the expense of efficiency. We demonstrate that on mitotic entry, kinetochores in cultured human cells form large crescents that subsequently compact into discrete structures on opposite sides of the centromere. This compaction occurs only after the formation of end-on microtubule attachments. Live-cell microscopy reveals that centromere rotation mediated by lateral kinetochore-microtubule interactions precedes the formation of end-on attachments and kinetochore compaction. Computational analyses of kinetochore expansion-compaction in the context of lateral interactions correctly predict experimentally observed spindle assembly times with reasonable error rates. The computational model suggests that larger kinetochores reduce both errors and assembly times, which can explain the robustness of spindle assembly and the functional significance of enlarged kinetochores.

  5. Constitutive Mad1 targeting to kinetochores uncouples checkpoint signalling from chromosome biorientation.

    Science.gov (United States)

    Maldonado, Maria; Kapoor, Tarun M

    2011-04-01

    Accurate chromosome segregation depends on biorientation, whereby sister chromatids attach to microtubules from opposite spindle poles. The spindle-assembly checkpoint is a surveillance mechanism in eukaryotes that inhibits anaphase until all chromosomes have bioriented. In present models, the recruitment of the spindle-assembly checkpoint protein Mad2, through Mad1, to non-bioriented kinetochores is needed to stop cell-cycle progression. However, it is unknown whether Mad1-Mad2 targeting to kinetochores is sufficient to block anaphase. Furthermore, it is unclear whether regulators of biorientation (for example, Aurora kinases) have checkpoint functions downstream of Mad1-Mad2 recruitment or whether they act upstream to quench the primary error signal. Here, we engineered a Mad1 construct that localizes to bioriented kinetochores. We show that the kinetochore localization of Mad1 is sufficient for a metaphase arrest that depends on Mad1-Mad2 binding. By uncoupling the checkpoint from its primary error signal, we show that Aurora, Mps1 and BubR1 kinases, but not Polo-like kinase, are needed to maintain checkpoint arrest when Mad1 is present on kinetochores. Together, our data suggest a model in which the biorientation errors, which recruit Mad1-Mad2 to kinetochores, may be signalled not only through Mad2 template dynamics, but also through the activity of widely conserved kinases, to ensure the fidelity of cell division.

  6. Complex regulation of sister kinetochore orientation in meiosis-I

    Indian Academy of Sciences (India)

    Amit Bardhan

    2010-09-01

    Kinetochores mediate chromosome movement during cell division by interacting with the spindle microtubules. Sexual reproduction necessitates the daunting task of reducing ploidy (number of chromosome sets) in the gametes, which depends upon the specialized properties of meiosis. Kinetochores have a central role in the reduction process. In this review, we discuss the complexity of this role of kinetochores in meiosis-I.

  7. 直结肠癌BUBR1的过度表达与TP53突变及微卫星状态关系提示其过度表达与染色体不稳定表型有关%Correlation between over expression of BUBR1 and chromosomal instability in colorectal carcinoma

    Institute of Scientific and Technical Information of China (English)

    赵岩; 张涛; 郑志超; 张剑军; 赵宜良; 前原喜彦

    2008-01-01

    Objective:Over expression of BUBR1 protein was reported in several human malignancies,however whether BUBR1 plays a role in chromosomal instability phenotype remains in controversy.This study was to explore the roll of BUBR1 protein in CIN phenotype in CRC.Methods:BUBR1 expression was studied immunohistochemieally in a panel of 93 advanced sporadic eolorectal cancers.Microsatellite status was evaluated by high resolution microsatellite analysis assay,TP53 gene mutation by direct sequencing and DNA ploidy by laser scanning cytometery.The relationship between BUBR1 overexpression and TP53 gene mutation,mierosatellite status,and DNA ploidy were studied.Results:BUBR1 overexpression was confirmed in 69% of cases.The overexpression was more frequent in tumor without high frequency microsatellite instability (P<0.01) and TP53 mutation (P<0.05).There was no statistic correlation between DNA aneuploidy and BUBR1 overexpression; however,a tendency that aneuploidy tumors had higher percentage of BUBR1 overexpression was shown.BUBR1 overexpression was not statistically related with clinieopathological factors.Conclusion:The linkage between BUBR1 overexpression and molecular factors indicating a CIN background implied that BUBR1 overexpression was indeed related with chromosomal instability in colorectal cancer.%在有丝分裂过程中BUBR1监视微管与着丝点的结合,是保证染色体均等分离的重要分子机制之一.BUBIB变异家谱研究及其敲除模型的研究表明,BUBR1缺陷与染色体不稳定性及肿瘤的发生直接相关.近来在数种人类肿瘤,对BUBR1蛋白过度表达有所报道.但在直结肠癌,BUBR1的过度表达是否与染色体不稳定性的发生有关目前仍无定论.在人类结直肠癌的遗传不稳定性主要表现为两种类型,染色体不稳定性及微卫星不稳定性,它们提示了两条独立的肿瘤发生路径.一般认为不存在高频度微卫星不稳定性表型的肿瘤通过染

  8. Movement of chromosomes with severed kinetochore microtubules.

    Science.gov (United States)

    Forer, Arthur; Johansen, Kristen M; Johansen, Jørgen

    2015-05-01

    Experiments dating from 1966 and thereafter showed that anaphase chromosomes continued to move poleward after their kinetochore microtubules were severed by ultraviolet microbeam irradiation. These observations were initially met with scepticism as they contradicted the prevailing view that kinetochore fibre microtubules pulled chromosomes to the pole. However, recent experiments using visible light laser microbeam irradiations have corroborated these earlier experiments as anaphase chromosomes again were shown to move poleward after their kinetochore microtubules were severed. Thus, multiple independent studies using different techniques have shown that chromosomes can indeed move poleward without direct microtubule connections to the pole, with only a kinetochore 'stub' of microtubules. An issue not yet settled is: what propels the disconnected chromosome? There are two not necessarily mutually exclusive proposals in the literature: (1) chromosome movement is propelled by the kinetochore stub interacting with non-kinetochore microtubules and (2) chromosome movement is propelled by a spindle matrix acting on the stub. In this review, we summarise the data indicating that chromosomes can move with severed kinetochore microtubules and we discuss proposed mechanisms for chromosome movement with severed kinetochore microtubules.

  9. Studying Kinetochore Kinases

    NARCIS (Netherlands)

    Saurin, Adrian T; Kops, Geert J P L

    2016-01-01

    Mitotic kinetochores are signaling network hubs that regulate chromosome movements, attachment error-correction, and the spindle assembly checkpoint. Key switches in these networks are kinases and phosphatases that enable rapid responses to changing conditions. Describing the mechanisms and dynamics

  10. Insights from an erroneous kinetochore-microtubule attachment state.

    Science.gov (United States)

    Cane, Stuart; McGilvray, Philip T; Maresca, Thomas J

    2013-01-01

    Faithful distribution of the genome requires that sister kinetochores, which assemble on each chromatid during cell division, interact with dynamic microtubules from opposite spindle poles in a configuration called chromosome biorientation. Biorientation produces tension that increases the affinity of kinetochores for microtubules via ill-defined mechanisms. Non-bioriented kinetochore-microtubule (kt-MT) interactions are prevalent but short-lived due to an error correction pathway that reduces the affinity of kinetochores for microtubules. Interestingly, incorrect kt-MT interactions can be stabilized by experimentally applying force to misoriented chromosomes. Here, a live-cell force assay is utilized to characterize the molecular composition of a common type of improper kt-MT attachment. Our force-related studies are also discussed in the context of current models for tension-dependent stabilization of kt-MT interactions.

  11. Conformational mechanism for the stability of microtubule-kinetochore attachments

    CERN Document Server

    Bertalan, Zsolt; Maiato, Helder; Zapperi, Stefano

    2014-01-01

    Regulating the stability of microtubule(MT)-kinetochore attachments is fundamental to avoiding mitotic errors and ensure proper chromosome segregation during cell division. While biochemical factors involved in this process have been identified, its mechanics still needs to be better understood. Here we introduce and simulate a mechanical model of MT-kinetochore interactions in which the stability of the attachment is ruled by the geometrical conformations of curling MT-protofilaments entangled in kinetochore fibrils. The model allows us to reproduce with good accuracy in vitro experimental measurements of the detachment times of yeast kinetochores from MTs under external pulling forces. Numerical simulations suggest that geometrical features of MT-protofilaments may play an important role in the switch between stable and unstable attachments.

  12. Looping in on Ndc80 - how does a protein loop at the kinetochore control chromosome segregation?

    DEFF Research Database (Denmark)

    Nilsson, Jakob

    2012-01-01

    Segregation of chromosomes during mitosis requires the interaction of dynamic microtubules with the kinetochore, a large protein structure established on the centromere region of sister chromatids. The core microtubule-binding activity of the kinetochore resides in the KMN network, an outer...

  13. Genome-Wide Synthetic Lethal Screens Identify an Interaction Between the Nuclear Envelope Protein, Apq12p, and the Kinetochore in Saccharomyces cerevisiae

    OpenAIRE

    Montpetit, Ben; Thorne, Ken; Barrett, Irene; Andrews, Kim; Jadusingh, Ravi; Hieter, Phil; Measday, Vivien

    2005-01-01

    The maintenance of genome stability is a fundamental requirement for normal cell cycle progression. The budding yeast Saccharomyces cerevisiae is an excellent model to study chromosome maintenance due to its well-defined centromere and kinetochore, the region of the chromosome and associated protein complex, respectively, that link chromosomes to microtubules. To identify genes that are linked to chromosome stability, we performed genome-wide synthetic lethal screens using a series of novel t...

  14. Mitosis in Oedogonium: spindle microfilaments and the origin of the kinetochore fiber.

    Science.gov (United States)

    Schibler, M J; Pickett-Heaps, J D

    1980-10-01

    New ultrastructural observations of mitosis in the closed spindle of Oedogonium cardiacum have been made using cells fixed with glutaraldehyde and tannic acid. Fine filaments 5 to 8 nm in diameter are attached to kinetochores from prophase through anaphase. Some are free in the early division nucleus while others emanate from forming kinetochores at prophase when few if any microtubules (MTs) are inside the nucleus. During prometaphase, MTs invade the nucleus from the poles and appear to interact with the microfilaments. Early in prometaphase, numerous MTs are laterally associated with kinetochores, and the kinetochore fiber is often formed first at one kinetochore of a pair. During metaphase and anaphase, the microfilaments are interspersed among the MTs of these kinetochore fibers. There also is an ill-defined matrix concentrated in the kinetochore fiber, and MTs are often coated irregularly with osmiophilic material. Live mitotic cells of Oedogonium were studied using time lapse cinematography, and we correlate these observations with the above results. We conclude that these microfilaments may constitute one structural component of the traction apparatus that moves chromosomes during metakinesis and anaphase, and that at least some (and possibly many) of the MTs of the kinetochore fiber are derived from those entering the nucleus at prometaphase.

  15. Evolutionary Turnover of Kinetochore Proteins: A Ship of Theseus?

    Science.gov (United States)

    Drinnenberg, Ines A; Henikoff, Steven; Malik, Harmit S

    2016-07-01

    The kinetochore is a multiprotein complex that mediates the attachment of a eukaryotic chromosome to the mitotic spindle. The protein composition of kinetochores is similar across species as divergent as yeast and human. However, recent findings have revealed an unexpected degree of compositional diversity in kinetochores. For example, kinetochore proteins that are essential in some species have been lost in others, whereas new kinetochore proteins have emerged in other lineages. Even in lineages with similar kinetochore composition, individual kinetochore proteins have functionally diverged to acquire either essential or redundant roles. Thus, despite functional conservation, the repertoire of kinetochore proteins has undergone recurrent evolutionary turnover.

  16. Paired arrangement of kinetochores together with microtubule pivoting and dynamics drive kinetochore capture in meiosis I.

    Science.gov (United States)

    Cojoc, Gheorghe; Florescu, Ana-Maria; Krull, Alexander; Klemm, Anna H; Pavin, Nenad; Jülicher, Frank; Tolić, Iva M

    2016-01-01

    Kinetochores are protein complexes on the chromosomes, whose function as linkers between spindle microtubules and chromosomes is crucial for proper cell division. The mechanisms that facilitate kinetochore capture by microtubules are still unclear. In the present study, we combine experiments and theory to explore the mechanisms of kinetochore capture at the onset of meiosis I in fission yeast. We show that kinetochores on homologous chromosomes move together, microtubules are dynamic and pivot around the spindle pole, and the average capture time is 3-4 minutes. Our theory describes paired kinetochores on homologous chromosomes as a single object, as well as angular movement of microtubules and their dynamics. For the experimentally measured parameters, the model reproduces the measured capture kinetics and shows that the paired configuration of kinetochores accelerates capture, whereas microtubule pivoting and dynamics have a smaller contribution. Kinetochore pairing may be a general feature that increases capture efficiency in meiotic cells.

  17. Kinetochore biorientation in Saccharomyces cerevisiae requires a tightly folded conformation of the Ndc80 complex.

    Science.gov (United States)

    Tien, Jerry F; Umbreit, Neil T; Zelter, Alex; Riffle, Michael; Hoopmann, Michael R; Johnson, Richard S; Fonslow, Bryan R; Yates, John R; MacCoss, Michael J; Moritz, Robert L; Asbury, Charles L; Davis, Trisha N

    2014-12-01

    Accurate transmission of genetic material relies on the coupling of chromosomes to spindle microtubules by kinetochores. These linkages are regulated by the conserved Aurora B/Ipl1 kinase to ensure that sister chromatids are properly attached to spindle microtubules. Kinetochore-microtubule attachments require the essential Ndc80 complex, which contains two globular ends linked by large coiled-coil domains. In this study, we isolated a novel ndc80 mutant in Saccharomyces cerevisiae that contains mutations in the coiled-coil domain. This ndc80 mutant accumulates erroneous kinetochore-microtubule attachments, resulting in misalignment of kinetochores on the mitotic spindle. Genetic analyses with suppressors of the ndc80 mutant and in vitro cross-linking experiments suggest that the kinetochore misalignment in vivo stems from a defect in the ability of the Ndc80 complex to stably fold at a hinge in the coiled coil. Previous studies proposed that the Ndc80 complex can exist in multiple conformations: elongated during metaphase and bent during anaphase. However, the distinct functions of individual conformations in vivo are unknown. Here, our analysis revealed a tightly folded conformation of the Ndc80 complex that is likely required early in mitosis. This conformation is mediated by a direct, intracomplex interaction and involves a greater degree of folding than the bent form of the complex at anaphase. Furthermore, our results suggest that this conformation is functionally important in vivo for efficient error correction by Aurora B/Ipl1 and, consequently, to ensure proper kinetochore alignment early in mitosis.

  18. Kinetochore microtubule establishment is defective in oocytes from aged mice.

    Science.gov (United States)

    Shomper, Maria; Lappa, Christina; FitzHarris, Greg

    2014-01-01

    Errors in chromosome segregation in mammalian oocytes increase in number with advancing maternal age, and are a major cause of pregnancy loss. Why chromosome segregation errors are more common in oocytes from older females remains poorly understood. In mitosis, accurate chromosome segregation is enabled by attachment of kinetochores to microtubules from appropriate spindle poles, and erroneous attachments increase the likelihood of mis-segregation. Whether attachment errors are responsible for age-related oocyte aneuploidy is unknown. Here we report that oocytes from naturally aged mice exhibit substantially increased chromosome misalignment, and fewer kinetochore pairs that make stable end-on attachments to the appropriate spindle poles compared with younger oocytes. The profile of mis-attachments exhibited is consistent with the types of chromosome segregation error observed in aged oocytes. Loss of chromosome cohesion, which is a feature of oocytes from older females, causes altered kinetochore geometry in meiosis-I. However, this has only a minor impact upon MT attachment, indicating that cohesion loss is not the primary cause of aneuploidy in meiosis-I. In meiosis-II, on the other hand, age-related cohesion loss plays a direct role in errors, since prematurely individualized sister chromatids misalign and misattach to spindle MTs. Thus, whereas cohesion loss leading to precocious sister chromatid separation is a direct cause of errors in meiosis-II, cohesion loss plays a more minor role in the etiology of aneuploidy in meiosis-I. Our data introduce altered MT-kinetochore interactions as a lesion that explains aneuploidy in meiosis-I in older females.

  19. Dynein at kinetochores: Making the connection.

    Science.gov (United States)

    McHugh, Toni; Welburn, Julie P I

    2017-04-03

    Dynein removes the checkpoint proteins from kinetochores once chromosomes are bioriented. In this issue, Gama et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201610108) and Mosalaganti et al. (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201611060) reveal the molecular basis for how dynein and its adaptor protein Spindly are recruited to the ROD-Zw10-Zwilch complex in the fibrous corona of unattached kinetochores.

  20. Kinetochore-microtubule attachment is sufficient to satisfy the human spindle assembly checkpoint.

    Science.gov (United States)

    Etemad, Banafsheh; Kuijt, Timo E F; Kops, Geert J P L

    2015-12-01

    The spindle assembly checkpoint (SAC) is a genome surveillance mechanism that protects against aneuploidization. Despite profound progress on understanding mechanisms of its activation, it remains unknown what aspect of chromosome-spindle interactions is monitored by the SAC: kinetochore-microtubule attachment or the force generated by dynamic microtubules that signals stable biorientation of chromosomes? To answer this, we uncoupled these two processes by expressing a non-phosphorylatable version of the main microtubule-binding protein at kinetochores (HEC1-9A), causing stabilization of incorrect kinetochore-microtubule attachments despite persistent activity of the error-correction machinery. The SAC is fully functional in HEC1-9A-expressing cells, yet cells in which chromosomes cannot biorient but are stably attached to microtubules satisfy the SAC and exit mitosis. SAC satisfaction requires neither intra-kinetochore stretching nor dynamic microtubules. Our findings support the hypothesis that in human cells the end-on interactions of microtubules with kinetochores are sufficient to satisfy the SAC without the need for microtubule-based pulling forces.

  1. Monopolin subunit Csm1 associates with MIND complex to establish monopolar attachment of sister kinetochores at meiosis I.

    Science.gov (United States)

    Sarkar, Sourav; Shenoy, Rajesh T; Dalgaard, Jacob Z; Newnham, Louise; Hoffmann, Eva; Millar, Jonathan B A; Arumugam, Prakash

    2013-01-01

    Sexually reproducing organisms halve their cellular ploidy during gametogenesis by undergoing a specialized form of cell division known as meiosis. During meiosis, a single round of DNA replication is followed by two rounds of nuclear divisions (referred to as meiosis I and II). While sister kinetochores bind to microtubules emanating from opposite spindle poles during mitosis, they bind to microtubules originating from the same spindle pole during meiosis I. This phenomenon is referred to as mono-orientation and is essential for setting up the reductional mode of chromosome segregation during meiosis I. In budding yeast, mono-orientation depends on a four component protein complex referred to as monopolin which consists of two nucleolar proteins Csm1 and Lrs4, meiosis-specific protein Mam1 of unknown function and casein kinase Hrr25. Monopolin complex binds to kinetochores during meiosis I and prevents bipolar attachments. Although monopolin associates with kinetochores during meiosis I, its binding site(s) on the kinetochore is not known and its mechanism of action has not been established. By carrying out an imaging-based screen we have found that the MIND complex, a component of the central kinetochore, is required for monopolin association with kinetochores during meiosis. Furthermore, we demonstrate that interaction of monopolin subunit Csm1 with the N-terminal domain of MIND complex subunit Dsn1, is essential for both the association of monopolin with kinetochores and for monopolar attachment of sister kinetochores during meiosis I. As such this provides the first functional evidence for a monopolin-binding site at the kinetochore.

  2. Cdk1 phosphorylation of the kinetochore protein Nsk1 prevents error-prone chromosome segregation.

    Science.gov (United States)

    Chen, Jun-Song; Lu, Lucy X; Ohi, Melanie D; Creamer, Kevin M; English, Chauca; Partridge, Janet F; Ohi, Ryoma; Gould, Kathleen L

    2011-11-14

    Cdk1 controls many aspects of mitotic chromosome behavior and spindle microtubule (MT) dynamics to ensure accurate chromosome segregation. In this paper, we characterize a new kinetochore substrate of fission yeast Cdk1, Nsk1, which promotes proper kinetochore-MT (k-MT) interactions and chromosome movements in a phosphoregulated manner. Cdk1 phosphorylation of Nsk1 antagonizes Nsk1 kinetochore and spindle localization during early mitosis. A nonphosphorylatable Nsk1 mutant binds prematurely to kinetochores and spindle, cementing improper k-MT attachments and leading to high rates of lagging chromosomes that missegregate. Accordingly, cells lacking nsk1 exhibit synthetic growth defects with mutations that disturb MT dynamics and/or kinetochore structure, and lack of proper phosphoregulation leads to even more severe defects. Intriguingly, Nsk1 is stabilized by binding directly to the dynein light chain Dlc1 independently of the dynein motor, and Nsk1-Dlc1 forms chainlike structures in vitro. Our findings establish new roles for Cdk1 and the Nsk1-Dlc1 complex in regulating the k-MT interface and chromosome segregation.

  3. The Monopolin Complex Crosslinks Kinetochore Components to Regulate Chromosome-Microtubule Attachments

    Energy Technology Data Exchange (ETDEWEB)

    Corbett, Kevin D.; Yip, Calvin K.; Ee, Ly-Sha; Walz, Thomas; Amon, Angelika; Harrison, Stephen C. (Harvard-Med); (MIT)

    2010-09-27

    The monopolin complex regulates different types of kinetochore-microtubule attachments in fungi, ensuring sister chromatid co-orientation in Saccharomyces cerevisiae meiosis I and inhibiting merotelic attachment in Schizosaccharomyces pombe mitosis. In addition, the monopolin complex maintains the integrity and silencing of ribosomal DNA (rDNA) repeats in the nucleolus. We show here that the S. cerevisiae Csm1/Lrs4 monopolin subcomplex has a distinctive V-shaped structure, with two pairs of protein-protein interaction domains positioned {approx}10 nm apart. Csm1 presents a conserved hydrophobic surface patch that binds two kinetochore proteins: Dsn1, a subunit of the outer-kinetochore MIND/Mis12 complex, and Mif2/CENP-C. Csm1 point-mutations that disrupt kinetochore-subunit binding also disrupt sister chromatid co-orientation in S. cerevisiae meiosis I. We further show that the same Csm1 point-mutations affect rDNA silencing, probably by disrupting binding to the rDNA-associated protein Tof2. We propose that Csm1/Lrs4 functions as a molecular clamp, crosslinking kinetochore components to enforce sister chromatid co-orientation in S. cerevisiae meiosis I and to suppress merotelic attachment in S. pombe mitosis, and crosslinking rDNA repeats to aid rDNA silencing.

  4. Abnormal kinetochore-generated pulling forces from expressing a N-terminally modified Hec1.

    Directory of Open Access Journals (Sweden)

    Marta Mattiuzzo

    Full Text Available BACKGROUND: Highly Expressed in Cancer protein 1 (Hec1 is a constituent of the Ndc80 complex, a kinetochore component that has been shown to have a fundamental role in stable kinetochore-microtubule attachment, chromosome alignment and spindle checkpoint activation at mitosis. HEC1 RNA is found up-regulated in several cancer cells, suggesting a role for HEC1 deregulation in cancer. In light of this, we have investigated the consequences of experimentally-driven Hec1 expression on mitosis and chromosome segregation in an inducible expression system from human cells. METHODOLOGY/PRINCIPAL FINDINGS: Overexpression of Hec1 could never be obtained in HeLa clones inducibly expressing C-terminally tagged Hec1 or untagged Hec1, suggesting that Hec1 cellular levels are tightly controlled. On the contrary, a chimeric protein with an EGFP tag fused to the Hec1 N-terminus accumulated in cells and disrupted mitotic division. EGFP- Hec1 cells underwent altered chromosome segregation within multipolar spindles that originated from centriole splitting. We found that EGFP-Hec1 assembled a mutant Ndc80 complex that was unable to rescue the mitotic phenotypes of Hec1 depletion. Kinetochores harboring EGFP-Hec1 formed persisting lateral microtubule-kinetochore interactions that recruited the plus-end depolymerase MCAK and the microtubule stabilizing protein HURP on K-fibers. In these conditions the plus-end kinesin CENP-E was preferentially retained at kinetochores. RNAi-mediated CENP-E depletion further demonstrated that CENP-E function was required for multipolar spindle formation in EGFP-Hec1 expressing cells. CONCLUSIONS/SIGNIFICANCE: Our study suggests that modifications on Hec1 N-terminal tail can alter kinetochore-microtubule attachment stability and influence Ndc80 complex function independently from the intracellular levels of the protein. N-terminally modified Hec1 promotes spindle pole fragmentation by CENP-E-mediated plus-end directed kinetochore

  5. Formation of stable attachments between kinetochores and microtubules depends on the B56-PP2A phosphatase.

    Science.gov (United States)

    Foley, Emily A; Maldonado, Maria; Kapoor, Tarun M

    2011-08-28

    Error-free chromosome segregation depends on the precise regulation of phosphorylation to stabilize kinetochore-microtubule attachments (K-fibres) on sister chromatids that have attached to opposite spindle poles (bi-oriented). In many instances, phosphorylation correlates with K-fibre destabilization. Consistent with this, multiple kinases, including Aurora B and Plk1, are enriched at kinetochores of mal-oriented chromosomes when compared with bi-oriented chromosomes, which have stable attachments. Paradoxically, however, these kinases also target to prometaphase chromosomes that have not yet established spindle attachments and it is therefore unclear how kinetochore-microtubule interactions can be stabilized when kinase levels are high. Here we show that the generation of stable K-fibres depends on the B56-PP2A phosphatase, which is enriched at centromeres/kinetochores of unattached chromosomes. When B56-PP2A is depleted, K-fibres are destabilized and chromosomes fail to align at the spindle equator. Strikingly, B56-PP2A depletion increases the level of phosphorylation of Aurora B and Plk1 kinetochore substrates as well as Plk1 recruitment to kinetochores. Consistent with increased substrate phosphorylation, we find that chemical inhibition of Aurora or Plk1 restores K-fibres in B56-PP2A-depleted cells. Our findings reveal that PP2A, an essential tumour suppressor, tunes the balance of phosphorylation to promote chromosome-spindle interactions during cell division.

  6. Human Zwint-1 Specifies Localization of Zeste White 10 to Kinetochores and Is Essential for Mitotic Checkpoint Signaling

    Institute of Scientific and Technical Information of China (English)

    HongmeiWang; XiaoyuHu; XiaDing; ZhenDou; ZhihongYank; AndrewW.Shaw; MaikunTcng; DonW.Cleveland; MichaelL.Goldberg; LiwenNiu; XucbiaoYao

    2005-01-01

    Chromosome segregation in mitosis is orchestrated by dynamic interaction between spindle microtubules and the kinetochore, a multiprotein complex assembled onto centromeric DNA of the chromosome. Here we show that Zwint-1 is required and is sufficient for kinetochore localization of Zestc White 10 (ZW10) in HeLa cells. Zwint-1 specifies the kinetochore association of ZW10 by interacting with its N-terminal domain. Suppression of synthesis of Zwint-1 by small interfering RNA abolishes the localization of ZW10 to the kinetochore, demonstrating the requirement of Zwint-1 for ZWl0 kinetochore localization. In addition, dcplction of Zwint-1 affects no mitotic arrest but causes aberrant premature chromo. some segregation. These Zwint-l-suppressed cells dis. play chromosome bridge phenotype with sister chromatids inter-connected. Moreover, Zwint-1 is required for stable association of CENP.F and dynamitin but not BUB1 with the kinetochore. Finally, our studies showthat Zwint-1 is a new component of the mitotic check. point, as cells lacking Zwint-1 fail to arrest in mitosis when exposed to microtubule inhibitors, yielding inter. phase cells with multinuclei. As ZWl0 and Zwint.1 are absent from yeast, we reasoned that metazoans evolved an elaborate spindle checkpoint machinery to ensure faithful chromosome segregation in mitosis.

  7. Kinetochore-microtubule attachment is sufficient to satisfy the human spindle assembly checkpoint

    NARCIS (Netherlands)

    Etemad, Banafsheh; Kuijt, Timo E F; Kops, Geert J P L

    2015-01-01

    The spindle assembly checkpoint (SAC) is a genome surveillance mechanism that protects against aneuploidization. Despite profound progress on understanding mechanisms of its activation, it remains unknown what aspect of chromosome-spindle interactions is monitored by the SAC: kinetochore-microtubule

  8. Dissection of the essential steps for condensin accumulation at kinetochores and rDNAs during fission yeast mitosis.

    Science.gov (United States)

    Nakazawa, Norihiko; Nakamura, Takahiro; Kokubu, Aya; Ebe, Masahiro; Nagao, Koji; Yanagida, Mitsuhiro

    2008-03-24

    The condensin complex has a fundamental role in chromosome dynamics. In this study, we report that accumulation of Schizosaccharomyces pombe condensin at mitotic kinetochores and ribosomal DNAs (rDNAs) occurs in multiple steps and is necessary for normal segregation of the sister kinetochores and rDNAs. Nuclear entry of condensin at the onset of mitosis requires Cut15/importin alpha and Cdc2 phosphorylation. Ark1/aurora and Cut17/Bir1/survivin are needed to dock the condensin at both the kinetochores and rDNAs. Furthermore, proteins that are necessary to form the chromatin architecture of the kinetochores (Mis6, Cnp1, and Mis13) and rDNAs (Nuc1 and Acr1) are required for condensin to accumulate specifically at these sites. Acr1 (accumulation of condensin at rDNA 1) is an rDNA upstream sequence binding protein that physically interacts with Rrn5, Rrn11, Rrn7, and Spp27 and is required for the proper accumulation of Nuc1 at rDNAs. The mechanism of condensin accumulation at the kinetochores may be conserved, as human condensin II fails to accumulate at kinetochores in hMis6 RNA interference-treated cells.

  9. Multimodal microtubule binding by the Ndc80 kinetochore complex.

    Science.gov (United States)

    Alushin, Gregory M; Musinipally, Vivek; Matson, Daniel; Tooley, John; Stukenberg, P Todd; Nogales, Eva

    2012-11-01

    The Ndc80 complex is a key site of kinetochore-microtubule attachment during cell division. The human complex engages microtubules with a globular 'head' formed by tandem calponin-homology domains and an 80-amino-acid unstructured 'tail' that contains sites of phosphoregulation by the Aurora B kinase. Using biochemical, cell biological and electron microscopy analyses, we dissected the roles of the tail in binding of microtubules and mediation of cooperative interactions between Ndc80 complexes. Two segments of the tail that contain Aurora B phosphorylation sites become ordered at interfaces; one with tubulin and the second with an adjacent Ndc80 head on the microtubule surface, forming interactions that are disrupted by phosphorylation. We propose a model in which Ndc80's interaction with either growing or shrinking microtubule ends can be tuned by the phosphorylation state of its tail.

  10. The kinetochore proteins Pcs1 and Mde4 and heterochromatin are required to prevent merotelic orientation

    NARCIS (Netherlands)

    Gregan, Juraj; Riedel, Christian G; Pidoux, Alison L; Katou, Yuki; Rumpf, Cornelia; Schleiffer, Alexander; Kearsey, Stephen E; Shirahige, Katsuhiko; Allshire, Robin C; Nasmyth, Kim

    2007-01-01

    BACKGROUND: Accurate chromosome segregation depends on the establishment of correct-amphitelic-kinetochore orientation. Merotelic kinetochore orientation is an error that occurs when a single kinetochore attaches to microtubules emanating from opposite spindle poles, a condition that hinders segrega

  11. CLIP-170 facilitates the formation of kinetochore-microtubule attachments.

    Science.gov (United States)

    Tanenbaum, Marvin E; Galjart, Niels; van Vugt, Marcel A T M; Medema, René H

    2006-01-11

    CLIP-170 is a microtubule 'plus end tracking' protein involved in several microtubule-dependent processes in interphase. At the onset of mitosis, CLIP-170 localizes to kinetochores, but at metaphase, it is no longer detectable at kinetochores. Although RNA interference (RNAi) experiments have suggested an essential role for CLIP-170 during mitosis, the molecular function of CLIP-170 in mitosis has not yet been revealed. Here, we used a combination of high-resolution microscopy and RNAi-mediated depletion to study the function of CLIP-170 in mitosis. We found that CLIP-170 dynamically localizes to the outer most part of unattached kinetochores and to the ends of growing microtubules. In addition, we provide evidence that a pool of CLIP-170 is transported along kinetochore-microtubules by the dynein/dynactin complex. Interference with CLIP-170 expression results in defective chromosome congression and diminished kinetochore-microtubule attachments, but does not detectibly affect microtubule dynamics or kinetochore-microtubule stability. Taken together, our results indicate that CLIP-170 facilitates the formation of kinetochore-microtubule attachments, possibly through direct capture of microtubules at the kinetochore.

  12. Sister kinetochores are mechanically fused during meiosis I in yeast.

    Science.gov (United States)

    Sarangapani, Krishna K; Duro, Eris; Deng, Yi; Alves, Flavia de Lima; Ye, Qiaozhen; Opoku, Kwaku N; Ceto, Steven; Rappsilber, Juri; Corbett, Kevin D; Biggins, Sue; Marston, Adèle L; Asbury, Charles L

    2014-10-10

    Production of healthy gametes requires a reductional meiosis I division in which replicated sister chromatids comigrate, rather than separate as in mitosis or meiosis II. Fusion of sister kinetochores during meiosis I may underlie sister chromatid comigration in diverse organisms, but direct evidence for such fusion has been lacking. We used laser trapping and quantitative fluorescence microscopy to study native kinetochore particles isolated from yeast. Meiosis I kinetochores formed stronger attachments and carried more microtubule-binding elements than kinetochores isolated from cells in mitosis or meiosis II. The meiosis I-specific monopolin complex was both necessary and sufficient to drive these modifications. Thus, kinetochore fusion directs sister chromatid comigration, a conserved feature of meiosis that is fundamental to Mendelian inheritance.

  13. 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.

  14. Differences in the origins of kinetochore-positive and kinetochore-negative micronuclei: A live cell imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Erkang, E-mail: erkangj@ustc.edu.cn

    2016-05-15

    Highlights: • Most Kinetochore-negative micronuclei were derived from kinetochore-negative displaced chromosomes, kinetochore-negative lagging chromosomes and fragments of broken chromosome bridges in mitosis of MN-free cells. • Most Kinetochore-positive micronuclei were derived from kinetochore-positive displaced chromosomes, kinetochore-positive lagging chromosomes and fragments of broken chromosome bridges in mitosis of MN-free cells. • Kinetochore-positive lagging chromosomes developed into kinetochore-positive micronuclei at the higher frequency than kinetochore-positive displaced chromosomes, kinetochore-negative lagging chromosomes developed into kinetochore-negative micronuclei at the higher rate than kinetochore-negative displaced chromosomes and broken chromosome bridges produced K−MNi and/or K+MNi. - Abstract: Micronuclei (MNi) are extensively used to evaluate genotoxicity and chromosomal instability. Classification of kinetochore-negative (K−MNi) and kinetochore-positive micronuclei (K+MNi) improves the specificity and sensitivity of the micronucleus (MN) test; however, the fundamental differences in the origins of K−MNi and K+MNi have not been addressed due to the limitations of traditional methods. In the current study, HeLa CENP B-GFP H2B-mCherry cells were constructed in which histone 2B (H2B) and centromere protein B (CENP B) were expressed as fusion proteins to monomeric Cherry (mCherry) and EGFP, respectively. MNi were identified using H2B-mCherry; K+MN contained CENP B-GFP, while K−MN did not. Long-term live cell imaging was conducted to examine MN formation in the dual-color fluorescent HeLa cells. The results suggested that K−MNi were derived from kinetochore-negative displaced chromosomes (K−DCs), kinetochore-negative lagging chromosomes (K−LCs) and fragments of broken chromosome bridges (CBs) during late mitotic stages. The results also indicated that K+MNi are derived from kinetochore-positive displaced chromosomes (K

  15. The Ndc80 complex: integrating the kinetochore's many movements.

    Science.gov (United States)

    Tooley, John; Stukenberg, P Todd

    2011-04-01

    The Ndc80 complex lies at the heart of the kinetochore, a large protein machine that accurately segregates chromosomes during cell division. The Ndc80 complex has structural roles in assembling the kinetochore, but also functions to congress chromosomes and to signal the spindle checkpoint. It directly binds to microtubules and is currently the best candidate for the long-sought protein that couples microtubule depolymerization to chromosome movement. A combination of structural and genetic data has recently converged to generate the first models for this fascinating motor activity. Additionally, recent data point to an increasingly dynamic role for Ndc80 in the kinetochore-one which involves not only simple binding to microtubules but also shifts in complex shape and its location within the overall kinetochore structure. In this review, we discuss recent advances in our understanding of the Ndc80 complex and address future areas of research.

  16. Ndc10 is a platform for inner kinetochore assembly in budding yeast

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Uhn-Soo; Harrison, Stephen C. (Harvard-Med)

    2012-01-10

    Kinetochores link centromeric DNA to spindle microtubules and ensure faithful chromosome segregation during mitosis. In point-centromere yeasts, the CBF3 complex Skp1-Ctf13-(Cep3){sub 2}-(Ndc10){sub 2} recognizes a conserved centromeric DNA element through contacts made by Cep3 and Ndc10. We describe here the five-domain organization of Kluyveromyces lactis Ndc10 and the structure at 2.8 {angstrom} resolution of domains I-II (residues 1-402) bound to DNA. The structure resembles tyrosine DNA recombinases, although it lacks both endonuclease and ligase activities. Structural and biochemical data demonstrate that each subunit of the Ndc10 dimer binds a separate fragment of DNA, suggesting that Ndc10 stabilizes a DNA loop at the centromere. We describe in vitro association experiments showing that specific domains of Ndc10 interact with each of the known inner-kinetochore proteins or protein complexes in budding yeast. We propose that Ndc10 provides a central platform for inner-kinetochore assembly.

  17. The CENP-A NAC/CAD kinetochore complex controls chromosome congression and spindle bipolarity.

    Science.gov (United States)

    McClelland, Sarah E; Borusu, Satyarebala; Amaro, Ana C; Winter, Jennifer R; Belwal, Mukta; McAinsh, Andrew D; Meraldi, Patrick

    2007-12-12

    Kinetochores are complex protein machines that link chromosomes to spindle microtubules and contain a structural core composed of two conserved protein-protein interaction networks: the well-characterized KMN (KNL1/MIND/NDC80) and the recently identified CENP-A NAC/CAD. Here we show that the CENP-A NAC/CAD subunits can be assigned to one of two different functional classes; depletion of Class I proteins (Mcm21R(CENP-O) and Fta1R(CENP-L)) causes a failure in bipolar spindle assembly. In contrast, depletion of Class II proteins (CENP-H, Chl4R(CENP-N), CENP-I and Sim4R(CENP-K)) prevents binding of Class I proteins and causes chromosome congression defects, but does not perturb spindle formation. Co-depletion of Class I and Class II proteins restores spindle bipolarity, suggesting that Class I proteins regulate or counteract the function of Class II proteins. We also demonstrate that CENP-A NAC/CAD and KMN regulate kinetochore-microtubule attachments independently, even though CENP-A NAC/CAD can modulate NDC80 levels at kinetochores. Based on our results, we propose that the cooperative action of CENP-A NAC/CAD subunits and the KMN network drives efficient chromosome segregation and bipolar spindle assembly during mitosis.

  18. Progress and perspective of the kinetochore-associated motor proteins

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The kinetochore is structurally composed of four layers. We know that three microtubule-based motor proteins such as CENP-E, dynein, and MCAK are located at the outmost region of the kinetochore. Experimentation of these motor functions betters our understanding of mitotic regulation, and chromosome movements in particular. With real-time studies of chromosome movements in live cells, we hope to illustrate the molecular mechanisms underlying mitotic regulation.

  19. Phosphorylation of Astrin Regulates Its Kinetochore Function.

    Science.gov (United States)

    Chung, Hee Jin; Park, Ji Eun; Lee, Nam Soo; Kim, Hongtae; Jang, Chang-Young

    2016-08-19

    The error-free segregation of chromosomes, which requires the precisely timed search and capture of chromosomes by spindles during early mitotic and meiotic cell division, is responsible for genomic stability and is achieved by the spindle assembly checkpoint in the metaphase-anaphase transition. Mitotic kinases orchestrate M phase events, such as the reorganization of cell architecture and kinetochore (KT) composition with the exquisite phosphorylation of mitotic regulators, to ensure timely and temporal progression. However, the molecular mechanisms underlying the changes of KT composition for stable spindle attachment during mitosis are poorly understood. Here, we show that the sequential action of the kinase Cdk1 and the phosphatase Cdc14A control spindle attachment to KTs. During prophase, the mitotic spindle protein Spag5/Astrin is transported into centrosomes by Kinastrin and phosphorylated at Ser-135 and Ser-249 by Cdk1, which, in prometaphase, is loaded onto the spindle and targeted to KTs. We also demonstrate that Cdc14A dephosphorylates Astrin, and therefore the overexpression of Cdc14A sequesters Astrin in the centrosome and results in aberrant chromosome alignment. Mechanistically, Plk1 acts as an upstream kinase for Astrin phosphorylation by Cdk1 and targeting phospho-Astrin to KTs, leading to the recruitment of outer KT components, such as Cenp-E, and the stable attachment of spindles to KTs. These comprehensive findings reveal a regulatory circuit for protein targeting to KTs that controls the KT composition change of stable spindle attachment and chromosome integrity.

  20. Dynein prevents erroneous kinetochore-microtubule attachments in mitosis.

    Science.gov (United States)

    Barisic, Marin; Maiato, Helder

    2015-01-01

    Equal distribution of the genetic material during cell division relies on efficient congression of chromosomes to the metaphase plate. Prior to their alignment, the Dynein motor recruited to kinetochores transports a fraction of laterally-attached chromosomes along microtubules toward the spindle poles. By doing that, Dynein not only contributes to chromosome movements, but also prevents premature stabilization of end-on kinetochore-microtubule attachments. This is achieved by 2 parallel mechanisms: 1) Dynein-mediated poleward movement of chromosomes counteracts opposite polar-ejection forces (PEFs) on chromosome arms by the microtubule plus-end-directed motors chromokinesins. Otherwise, they could stabilize erroneous syntelic kinetochore-microtubule attachments and lead to the random ejection of chromosomes away from the spindle poles; and 2) By transporting chromosomes to the spindle poles, Dynein brings the former to the zone of highest Aurora A kinase activity, further destabilizing kinetochore-microtubule attachments. Thus, Dynein plays an important role in keeping chromosome segregation error-free by preventing premature stabilization of kinetochore-microtubule attachments near the spindle poles.

  1. Synergistic Control of Kinetochore Protein Levels by Psh1 and Ubr2.

    Directory of Open Access Journals (Sweden)

    Eva Herrero

    2016-02-01

    Full Text Available The accurate segregation of chromosomes during cell division is achieved by attachment of chromosomes to the mitotic spindle via the kinetochore, a large multi-protein complex that assembles on centromeres. The budding yeast kinetochore comprises more than 60 different proteins. Although the structure and function of many of these proteins has been investigated, we have little understanding of the steady state regulation of kinetochores. The primary model of kinetochore homeostasis suggests that kinetochores assemble hierarchically from the centromeric DNA via the inclusion of a centromere-specific histone into chromatin. We tested this model by trying to perturb kinetochore protein levels by overexpressing an outer kinetochore gene, MTW1. This increase in protein failed to change protein recruitment, consistent with the hierarchical assembly model. However, we find that deletion of Psh1, a key ubiquitin ligase that is known to restrict inner kinetochore protein loading, does not increase levels of outer kinetochore proteins, thus breaking the normal kinetochore stoichiometry. This perturbation leads to chromosome segregation defects, which can be partially suppressed by mutation of Ubr2, a second ubiquitin ligase that normally restricts protein levels at the outer kinetochore. Together these data show that Psh1 and Ubr2 synergistically control the amount of proteins at the kinetochore.

  2. The Ndc80 internal loop is required for recruitment of the Ska complex to establish end-on microtubule attachment to kinetochores

    DEFF Research Database (Denmark)

    Zhang, Gang; Kelstrup, Christian D; Hu, Xiao-Wen;

    2012-01-01

    the chromosomes and stable kinetochore fibers are absent. Through quantitative mass spectrometry and immunofluorescence we find that the binding of the Ska complex depends on the loop region explaining why end-on attachment is defective. This underscores the importance of the Ndc80 loop region in coordinating......The Ndc80 complex establishes end-on attachment of kinetochores to microtubules essential for chromosome segregation. The Ndc80 subunit is characterized by an N-terminal region, that binds directly to microtubules, and a long coiled-coil region that interacts with Nuf2. A loop region in Ndc80...

  3. Geometry and force behind kinetochore orientation: lessons from meiosis.

    Science.gov (United States)

    Watanabe, Yoshinori

    2012-05-16

    During mitosis, replicated chromosomes (sister chromatids) become attached at the kinetochore by spindle microtubules emanating from opposite poles and segregate equationally. In the first division of meiosis, however, sister chromatids become attached from the same pole and co-segregate, whereas homologous chromosomes connected by chiasmata segregate to opposite poles. Disorder in this specialized chromosome attachment in meiosis is the leading cause of miscarriage in humans. Recent studies have elucidated the molecular mechanisms determining chromosome orientation, and consequently segregation, in meiosis. Comparative studies of meiosis and mitosis have led to the general principle that kinetochore geometry and tension exerted by microtubules synergistically generate chromosome orientation.

  4. 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.

  5. Cutting edge science: Laser surgery illuminates viscoelasticity of merotelic kinetochores.

    Science.gov (United States)

    Cabello, Simon; Gachet, Yannick; Tournier, Sylvie

    2016-03-28

    Increasing evidence in eukaryotic cells suggests that mechanical forces are essential for building a robust mitotic apparatus and correcting inappropriate chromosome attachments. In this issue, Cojoc et al. (2016. J. Cell Biol., http://dx.doi.org/10.1083/jcb.201506011) use laser microsurgery in vivo to measure and study the viscoelastic properties of kinetochores.

  6. Multi-modal microtubule binding by the Ndc80 kinetochore complex

    Science.gov (United States)

    Alushin, Gregory M.; Musinipally, Vivek; Matson, Daniel; Tooley, John; Stukenberg, P. Todd; Nogales, Eva

    2012-01-01

    Summary The Ndc80 complex is a key site of kinetochore-microtubule attachment during cell division. The human complex engages microtubules with a globular “head” formed by tandem calponin-homology domains and an 80 amino-acid unstructured “tail” that contains sites of phospho-regulation by the Aurora B kinase. Using biochemical, cell biological, and electron microscopy analyses, we have dissected the tail’s roles in microtubule binding and mediating cooperative interactions between Ndc80 complexes. Two segments of the tail that contain Aurora B sites become ordered at interfaces; one with tubulin and the second with an adjacent Ndc80 head on the microtubule surface, forming interactions which are disrupted by phosphorylation. We propose a model in which Ndc80’s interaction with either growing or shrinking microtubule ends can be tuned by the phosphorylation state of its tail. PMID:23085714

  7. Kinetochore microtubule establishment is defective in oocytes from aged mice

    OpenAIRE

    Shomper, Maria; Lappa, Christina; FitzHarris, Greg

    2014-01-01

    Errors in chromosome segregation in mammalian oocytes increase in number with advancing maternal age, and are a major cause of pregnancy loss. Why chromosome segregation errors are more common in oocytes from older females remains poorly understood. In mitosis, accurate chromosome segregation is enabled by attachment of kinetochores to microtubules from appropriate spindle poles, and erroneous attachments increase the likelihood of mis-segregation. Whether attachment errors are responsible fo...

  8. Dynactin helps target Polo-like kinase 1 to kinetochores via its left-handed beta-helical p27 subunit.

    Science.gov (United States)

    Yeh, Ting-Yu; Kowalska, Anna K; Scipioni, Brett R; Cheong, Frances Ka Yan; Zheng, Meiying; Derewenda, Urszula; Derewenda, Zygmunt S; Schroer, Trina A

    2013-04-01

    Dynactin is a protein complex required for the in vivo function of cytoplasmic dynein, a microtubule (MT)-based motor. Dynactin binds both dynein and MTs via its p150(Glued) subunit, but little is known about the 'pointed-end complex' that includes the protein subunits Arp11, p62 and the p27/p25 heterodimer. Here, we show that the p27/p25 heterodimer undergoes mitotic phosphorylation by cyclin-dependent kinase 1 (Cdk1) at a single site, p27 Thr186, to generate an anchoring site for polo-like kinase 1 (Plk1) at kinetochores. Removal of p27/p25 from dynactin results in reduced levels of Plk1 and its phosphorylated substrates at kinetochores in prometaphase, which correlates with aberrant kinetochore-MT interactions, improper chromosome alignment and abbreviated mitosis. To investigate the structural implications of p27 phosphorylation, we determined the structure of human p27. This revealed an unusual left-handed β-helix domain, with the phosphorylation site located within a disordered, C-terminal segment. We conclude that dynactin plays a previously undescribed regulatory role in the spindle assembly checkpoint by recruiting Plk1 to kinetochores and facilitating phosphorylation of important downstream targets.

  9. Kinetochore dynein generates a poleward pulling force to facilitate congression and full chromosome alignment

    Institute of Scientific and Technical Information of China (English)

    Yan Li; Wei Yu; Yun Liang; Xueliang Zhu

    2007-01-01

    For proper chromosome segregation, all kinetochores must achieve bipolar microtubule (MT) attachment and subsequently align at the spindle equator before anaphase onset. The MT minus end-directed motor dynein/dynactin binds kinetochores in prometaphase and has long been implicated in chromosome congression. Unfortunately, inactivation of dynein usually disturbs spindle organization, thus hampering evaluation of its kinetochore roles. Here we specifically eliminated kinetochore dynein/dynactin by RNAi-mediated depletion of ZW10, a protein essential for kinetochore localization of the motor. Time-lapse microscopy indicated markedly-reduced congression efficiency, though congressing chromosomes displayed similar velocities as in control cells. Moreover, cells frequently failed to achieve full chromosome alignment, despite their normal spindles. Confocal microcopy revealed that the misaligned kinetochores were monoori-ented or unattached and mostly lying outside the spindle, suggesting a difficulty to capture MTs from the opposite pole. Kinetochores on monoastral spindles were dispersed farther away from the pole and exhibited only mild oscillation. Furthermore, inactivating dynein by other means generated similar phenotypes. Therefore, kinetochore dynein produces on monooriented kinetochores a poleward pulling force, which may contribute to efficient bipolar attachment by facilitating their proper microtubule captures to promote congression as well as full chromosome alignment.

  10. Joined at the hip: kinetochores, microtubules, and spindle assembly checkpoint signaling.

    Science.gov (United States)

    Sacristan, Carlos; Kops, Geert J P L

    2015-01-01

    Error-free chromosome segregation relies on stable connections between kinetochores and spindle microtubules. The spindle assembly checkpoint (SAC) monitors such connections and relays their absence to the cell cycle machinery to delay cell division. The molecular network at kinetochores that is responsible for microtubule binding is integrated with the core components of the SAC signaling system. Molecular-mechanistic understanding of how the SAC is coupled to the kinetochore-microtubule interface has advanced significantly in recent years. The latest insights not only provide a striking view of the dynamics and regulation of SAC signaling events at the outer kinetochore but also create a framework for understanding how that signaling may be terminated when kinetochores and microtubules connect.

  11. Kinetochores coordinate pericentromeric cohesion and early DNA replication by Cdc7-Dbf4 kinase recruitment.

    Science.gov (United States)

    Natsume, Toyoaki; Müller, Carolin A; Katou, Yuki; Retkute, Renata; Gierliński, Marek; Araki, Hiroyuki; Blow, J Julian; Shirahige, Katsuhiko; Nieduszynski, Conrad A; Tanaka, Tomoyuki U

    2013-06-01

    Centromeres play several important roles in ensuring proper chromosome segregation. Not only do they promote kinetochore assembly for microtubule attachment, but they also support robust sister chromatid cohesion at pericentromeres and facilitate replication of centromeric DNA early in S phase. However, it is still elusive how centromeres orchestrate all these functions at the same site. Here, we show that the budding yeast Dbf4-dependent kinase (DDK) accumulates at kinetochores in telophase, facilitated by the Ctf19 kinetochore complex. This promptly recruits Sld3-Sld7 replication initiator proteins to pericentromeric replication origins so that they initiate replication early in S phase. Furthermore, DDK at kinetochores independently recruits the Scc2-Scc4 cohesin loader to centromeres in G1 phase. This enhances cohesin loading and facilitates robust pericentromeric cohesion in S phase. Thus, we have found the central mechanism by which kinetochores orchestrate early S phase DNA replication and robust sister chromatid cohesion at microtubule attachment sites.

  12. A stochastic model of kinetochore-microtubule attachment accurately describes fission yeast chromosome segregation.

    Science.gov (United States)

    Gay, Guillaume; Courtheoux, Thibault; Reyes, Céline; Tournier, Sylvie; Gachet, Yannick

    2012-03-19

    In fission yeast, erroneous attachments of spindle microtubules to kinetochores are frequent in early mitosis. Most are corrected before anaphase onset by a mechanism involving the protein kinase Aurora B, which destabilizes kinetochore microtubules (ktMTs) in the absence of tension between sister chromatids. In this paper, we describe a minimal mathematical model of fission yeast chromosome segregation based on the stochastic attachment and detachment of ktMTs. The model accurately reproduces the timing of correct chromosome biorientation and segregation seen in fission yeast. Prevention of attachment defects requires both appropriate kinetochore orientation and an Aurora B-like activity. The model also reproduces abnormal chromosome segregation behavior (caused by, for example, inhibition of Aurora B). It predicts that, in metaphase, merotelic attachment is prevented by a kinetochore orientation effect and corrected by an Aurora B-like activity, whereas in anaphase, it is corrected through unbalanced forces applied to the kinetochore. These unbalanced forces are sufficient to prevent aneuploidy.

  13. 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.

  14. Meikin is a conserved regulator of meiosis-I-specific kinetochore function.

    Science.gov (United States)

    Kim, Jihye; Ishiguro, Kei-ichiro; Nambu, Aya; Akiyoshi, Bungo; Yokobayashi, Shihori; Kagami, Ayano; Ishiguro, Tadashi; Pendas, Alberto M; Takeda, Naoki; Sakakibara, Yogo; Kitajima, Tomoya S; Tanno, Yuji; Sakuno, Takeshi; Watanabe, Yoshinori

    2015-01-22

    The kinetochore is the crucial apparatus regulating chromosome segregation in mitosis and meiosis. Particularly in meiosis I, unlike in mitosis, sister kinetochores are captured by microtubules emanating from the same spindle pole (mono-orientation) and centromeric cohesion mediated by cohesin is protected in the following anaphase. Although meiotic kinetochore factors have been identified only in budding and fission yeasts, these molecules and their functions are thought to have diverged earlier. Therefore, a conserved mechanism for meiotic kinetochore regulation remains elusive. Here we have identified in mouse a meiosis-specific kinetochore factor that we termed MEIKIN, which functions in meiosis I but not in meiosis II or mitosis. MEIKIN plays a crucial role in both mono-orientation and centromeric cohesion protection, partly by stabilizing the localization of the cohesin protector shugoshin. These functions are mediated mainly by the activity of Polo-like kinase PLK1, which is enriched to kinetochores in a MEIKIN-dependent manner. Our integrative analysis indicates that the long-awaited key regulator of meiotic kinetochore function is Meikin, which is conserved from yeasts to humans.

  15. A neocentromere on human chromosome 3 without detectable alpha-satellite DNA forms morphologically normal kinetochores

    DEFF Research Database (Denmark)

    Wandall, A; Tranebjaerg, L; Tommerup, Niels

    1998-01-01

    A neocentromere at 3q26 was observed in a father and his daughter on a chromosome 3 with deleted centromeric region. No alpha-satellite DNA was detectable at the 3q26 neocentromere, but it was weakly positive with anticentromere (CREST) antibodies. Electron microscopy showed that the neocentromere...... formed microtubule-associated kinetochores with normal morphology and of the same size as the kinetochores of other large chromosomes. The deleted centromere formed a small linear marker chromosome that reacted strongly with anticentromere antibodies, but showed reduced kinetochore size. The 3q26...

  16. Production and initial characterization of Dad1p, a component of the Dam1-DASH kinetochore complex.

    Directory of Open Access Journals (Sweden)

    Jennifer Waldo

    Full Text Available In all dividing eukaryotic cells, the mitotic spindle (composed primarily of microtubules must interact with chromosomes through a complex protein assembly called the kinetochore. In Saccharomyces cerevisiae, the Dam1-DASH complex plays an important role in promoting attachment between the kinetochore and the mitotic spindle. It also actively participates in the physical separation of sister chromatids in anaphase. Understanding the biochemical mechanisms used by Dam1-DASH has been facilitated by bacterial co-expression of the ten Dam1-DASH genes, which results in the production of a heterodecameric protein complex that can be studied in vitro. However, individual protein subunits are not soluble when expressed in E. coli, thus precluding analysis of the nature of the interaction between subunits and an examination of the assembly of the functional complex. In this paper, we describe the expression, solubilization, purification and refolding of Dad1p, one of the Dam1-DASH complex subunits. In addition, we show that Dad1p, when isolated in this manner forms dimers and/or tetramers, dependent upon protein concentration. This work provides an important tool for studying the Dam1-DASH complex that was previously unavailable, and provides an avenue of investigation for understanding how the individual heterodecamers associate with each other to facilitate chromosome segregation.

  17. Contributions of microtubule dynamic instability and rotational diffusion to kinetochore capture

    CERN Document Server

    Blackwell, Robert; Edelmaier, Christopher; Gergely, Zachary R; Flynn, Patrick J; Montes, Salvador; Crapo, Ammon; Doostan, Alireza; McIntosh, J Richard; Glaser, Matthew A; Betterton, Meredith D

    2016-01-01

    Microtubule dynamic instability allows search and capture of kinetochores during spindle formation, an important process for accurate chromosome segregation during cell division. Recent work has found that microtubule rotational diffusion about minus-end attachment points contributes to kinetochore capture in fission yeast, but the relative contributions of dynamic instability and rotational diffusion are not well understood. We have developed a biophysical model of kinetochore capture in small fission-yeast nuclei using hybrid Brownian dynamics/kinetic Monte Carlo simulation techniques. With this model, we have studied the importance of dynamic instability and microtubule rotational diffusion for kinetochore capture, both to the lateral surface of a microtubule and at or near its end. Over a range of biologically relevant parameters, microtubule rotational diffusion decreased capture time, but made a relatively small contribution compared to dynamic instability. At most, rotational diffusion reduced capture ...

  18. 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.

  19. The chromosomal passenger complex and the spindle assembly checkpoint: kinetochore-microtubule error correction and beyond

    Directory of Open Access Journals (Sweden)

    Maia André F

    2008-05-01

    Full Text Available Abstract During mitosis, correct bipolar chromosome attachment to the mitotic spindle is an essential prerequisite for the equal segregation of chromosomes. The spindle assembly checkpoint can prevent chromosome segregation as long as not all chromosome pairs have obtained bipolar attachment to the spindle. The chromosomal passenger complex plays a crucial role during chromosome alignment by correcting faulty chromosome-spindle interactions (e.g. attachments that do not generate tension. In the process of doing so, the chromosomal passenger complex generates unattached chromosomes, a specific situation that is known to promote checkpoint activity. However, several studies have implicated an additional, more direct role for the chromosomal passenger complex in enforcing the mitotic arrest imposed by the spindle assembly checkpoint. In this review, we discuss the different roles played by the chromosomal passenger complex in ensuring proper mitotic checkpoint function. Additionally, we discuss the possibility that besides monitoring the presence of unattached kinetochores, the spindle assembly checkpoint may also be capable of responding to chromosome-microtubule interactions that do not generate tension and we propose experimental set-ups to study this.

  20. The chromosomal passenger complex and the spindle assembly checkpoint: kinetochore-microtubule error correction and beyond.

    Science.gov (United States)

    Vader, Gerben; Maia, André F; Lens, Susanne Ma

    2008-05-28

    During mitosis, correct bipolar chromosome attachment to the mitotic spindle is an essential prerequisite for the equal segregation of chromosomes. The spindle assembly checkpoint can prevent chromosome segregation as long as not all chromosome pairs have obtained bipolar attachment to the spindle. The chromosomal passenger complex plays a crucial role during chromosome alignment by correcting faulty chromosome-spindle interactions (e.g. attachments that do not generate tension). In the process of doing so, the chromosomal passenger complex generates unattached chromosomes, a specific situation that is known to promote checkpoint activity. However, several studies have implicated an additional, more direct role for the chromosomal passenger complex in enforcing the mitotic arrest imposed by the spindle assembly checkpoint. In this review, we discuss the different roles played by the chromosomal passenger complex in ensuring proper mitotic checkpoint function. Additionally, we discuss the possibility that besides monitoring the presence of unattached kinetochores, the spindle assembly checkpoint may also be capable of responding to chromosome-microtubule interactions that do not generate tension and we propose experimental set-ups to study this.

  1. Spatial Rule-Based Modeling: A Method and Its Application to the Human Mitotic Kinetochore

    Directory of Open Access Journals (Sweden)

    Jan Huwald

    2013-07-01

    Full Text Available A common problem in the analysis of biological systems is the combinatorial explosion that emerges from the complexity of multi-protein assemblies. Conventional formalisms, like differential equations, Boolean networks and Bayesian networks, are unsuitable for dealing with the combinatorial explosion, because they are designed for a restricted state space with fixed dimensionality. To overcome this problem, the rule-based modeling language, BioNetGen, and the spatial extension, SRSim, have been developed. Here, we describe how to apply rule-based modeling to integrate experimental data from different sources into a single spatial simulation model and how to analyze the output of that model. The starting point for this approach can be a combination of molecular interaction data, reaction network data, proximities, binding and diffusion kinetics and molecular geometries at different levels of detail. We describe the technique and then use it to construct a model of the human mitotic inner and outer kinetochore, including the spindle assembly checkpoint signaling pathway. This allows us to demonstrate the utility of the procedure, show how a novel perspective for understanding such complex systems becomes accessible and elaborate on challenges that arise in the formulation, simulation and analysis of spatial rule-based models.

  2. Reconstruction of the kinetochore: a prelude to meiosis

    Directory of Open Access Journals (Sweden)

    Haraguchi Tokuko

    2007-06-01

    Full Text Available Abstract In eukaryotic organisms, chromosomes are spatially organized within the nucleus. Such nuclear architecture provides a physical framework for the genetic activities of chromosomes, and changes its functional organization as the cell moves through the phases of the cell cycle. The fission yeast Schizosaccharomyces pombe provides a striking example of nuclear reorganization during the transition from mitosis to meiosis. In this organism, centromeres remain clustered at the spindle-pole body (SPB; a centrosome-equivalent structure in fungi during mitotic interphase. In contrast, during meiotic prophase, centromeres dissociate from the SPB and telomeres cluster to the SPB. Recent studies revealed that this repositioning of chromosomes is regulated by mating pheromone signaling. Some centromere proteins disappear from the centromere in response to mating pheromone, leading to dissociation of centromeres from the SPB. Interestingly, mating pheromone signaling is also required for monopolar orientation of the kinetochore which is crucial for proper segregation of sister chromatids during meiosis. When meiosis is induced in the absence of mating pheromone signaling, aberrant chromosome behaviors are observed: the centromere proteins remain at the centromere; the centromere remains associated with the SPB; and sister chromatids segregate precociously in the first meiotic division. These aberrant chromosome behaviors are all normalized by activating the mating pheromone signaling pathway. Thus, action of mating pheromone on the centromere is important for coherent behavior of chromosomes in meiosis. Here we discuss repositioning and reconstruction of the centromere during the transition from mitosis to meiosis, and highlight its significance for proper progression of meiosis.

  3. Synchronizing chromosome segregation by flux-dependent force equalization at kinetochores.

    Science.gov (United States)

    Matos, Irina; Pereira, António J; Lince-Faria, Mariana; Cameron, Lisa A; Salmon, Edward D; Maiato, Helder

    2009-07-13

    The synchronous movement of chromosomes during anaphase ensures their correct inheritance in every cell division. This reflects the uniformity of spindle forces acting on chromosomes and their simultaneous entry into anaphase. Although anaphase onset is controlled by the spindle assembly checkpoint, it remains unknown how spindle forces are uniformly distributed among different chromosomes. In this paper, we show that tension uniformity at metaphase kinetochores and subsequent anaphase synchrony in Drosophila S2 cells are promoted by spindle microtubule flux. These results can be explained by a mechanical model of the spindle where microtubule poleward translocation events associated with flux reflect relaxation of the kinetochore-microtubule interface, which accounts for the redistribution and convergence of kinetochore tensions in a timescale comparable to typical metaphase duration. As predicted by the model, experimental acceleration of mitosis precludes tension equalization and anaphase synchrony. We propose that flux-dependent equalization of kinetochore tensions ensures a timely and uniform maturation of kinetochore-microtubule interfaces necessary for error-free and coordinated segregation of chromosomes in anaphase.

  4. Kinetochore-independent chromosome poleward movement during anaphase of meiosis II in mouse eggs.

    Directory of Open Access Journals (Sweden)

    Manqi Deng

    Full Text Available Kinetochores are considered to be the key structures that physically connect spindle microtubules to the chromosomes and play an important role in chromosome segregation during mitosis. Due to different mechanisms of spindle assembly between centrosome-containing mitotic cells and acentrosomal meiotic oocytes, it is unclear how a meiotic spindle generates the poleward forces to drive two rounds of meiotic chromosome segregation to achieve genome haploidization. We took advantage of the fact that DNA beads are able to induce bipolar spindle formation without kinetochores and studied the behavior of DNA beads in the induced spindle in mouse eggs during meiosis II. Interestingly, DNA beads underwent poleward movements that were similar in timing and speed to the meiotic chromosomes, although all the beads moved together to the same spindle pole. Disruption of dynein function abolished the poleward movements of DNA beads but not of the meiotic chromosomes, suggesting the existence of different dynein-dependent and dynein-independent force generation mechanisms for the chromosome poleward movement, and the latter may be dependent on the presence of kinetochores. Consistent with the observed DNA bead poleward movement, sperm haploid chromatin (which also induced bipolar spindle formation after injection to a metaphase egg without forming detectable kinetochore structures also underwent similar poleward movement at anaphase as DNA beads. The results suggest that in the chromatin-induced meiotic spindles, kinetochore attachments to spindle microtubules are not absolutely required for chromatin poleward movements at anaphase.

  5. CENP-K and CENP-H may form coiled-coils in the kinetochores

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Kinetochores are large proteinaceous structure on the surface of chromosomes’ primary constriction during mitosis. They link chromosomes to spindle microtubules and also regulate the spindle assem- bly checkpoint, which is crucial for correct chromosome segregation in all eukaryotes. The better known core networks of kinetochores include the KMN network (K, KNL1; M, Mis12 complex; N, Ndc80 complex)and CCAN (constitutive centromere-associated network). However, the detailed molecular mechanism of the kinetochore protein network remains unclear. This study demonstrates that CENP-H and CENP-K form quite stable subcomplex by TAP (tandem affinity purification) with HEK 293 cells which express TAP-CENP-K, with the ratio of purified CENP-H and CENP-K being close to 1︰1 even with high salt. Bioinformatic analysis suggests that CENP-H and CENP-K are enriched with coiled-coil regions. This implies that CENP-H and CENP-K form heterodimeric coiled-coils. Furthermore, the func- tional regions which form the complex are respectively located on their N- and C-terminals, but the association between the C-terminals is more complex. It is possible that this is the first identified het- erodimeric coiled-coils within the inner kinetochore, which is directly involved in the attachment be- tween kinetochores and the spindle microtubules.

  6. CENP-K and CENP-H may form coiled-coils in the kinetochores

    Institute of Scientific and Technical Information of China (English)

    QIU ShuLan; WANG JiaNing; YU Chuang; HE DaCheng

    2009-01-01

    Kinetochores are large proteinaceous structure on the surface of chromosomes' primary constriction during mitosis. They link chromosomes to spindle microtubules and also regulate the spindle assem-bly checkpoint, which is crucial for correct chromosome segregation in all eukaryotes. The better known core networks of kinetochores include the KMN network (K, KNL1; M, Mis12 complex; N, Ndc80 complex)and CCAN (constitutive centromere-associated network). However, the detailed molecular mechanism of the kinetochore protein network remains unclear. This study demonstrates that CENP-H and CENP-K form quite stable subcomplex by TAP (tandem affinity purification) with HEK 293 cells which express TAP-CENP-K, with the ratio of purified CENP-H and CENP-K being close to 1 : 1 even with high salt. Bioinformatic analysis suggests that CENP-H and CENP-K are enriched with coiled-coil regions. This implies that CENP-H and CENP-K form heterodimeric coiled-coils. Furthermore, the func-tional regions which form the complex are respectively located on their N- and C-terminals, but the association between the C-terminals is more complex. It is possible that this is the first identified het-erodimeric coiled-coils within the inner kinetochore, which is directly involved in the attachment be-tween kinetochores and the spindle microtubules.

  7. HURP is a Ran-importin beta-regulated protein that stabilizes kinetochore microtubules in the vicinity of chromosomes

    NARCIS (Netherlands)

    Silljé, Herman H W; Nagel, Susanna; Körner, Roman; Nigg, Erich A

    2006-01-01

    BACKGROUND: Formation of a bipolar mitotic spindle in somatic cells requires the cooperation of two assembly pathways, one based on kinetochore capture by centrosomal microtubules, the other on RanGTP-mediated microtubule organization in the vicinity of chromosomes. How RanGTP regulates kinetochore-

  8. Mislocalization of the Drosophila centromere-specific histone CIDpromotes formation of functional ectopic kinetochores

    Energy Technology Data Exchange (ETDEWEB)

    Heun, Patrick; Erhardt, Sylvia; Blower, Michael D.; Weiss,Samara; Skora, Andrew D.; Karpen, Gary H.

    2006-01-30

    The centromere-specific histone variant CENP-A (CID in Drosophila) is a structural and functional foundation for kinetochore formation and chromosome segregation. Here, we show that overexpressed CID is mislocalized into normally non-centromeric regions in Drosophila tissue culture cells and animals. Analysis of mitoses in living and fixed cells reveals that mitotic delays, anaphase bridges, chromosome fragmentation, and cell and organismal lethality are all direct consequences of CID mislocalization. In addition, proteins that are normally restricted to endogenous kinetochores assemble at a subset of ectopic CID incorporation regions. The presence of microtubule motors and binding proteins, spindle attachments, and aberrant chromosome morphologies demonstrate that these ectopic kinetochores are functional. We conclude that CID mislocalization promotes formation of ectopic centromeres and multicentric chromosomes, which causes chromosome missegregation, aneuploidy, and growth defects. Thus, CENP-A mislocalization is one possible mechanism for genome instability during cancer progression, as well as centromere plasticity during evolution.

  9. A direct role of Mad1 in the spindle assembly checkpoint beyond Mad2 kinetochore recruitment

    DEFF Research Database (Denmark)

    Kruse, Thomas; Larsen, Marie Sofie Yoo; Sedgwick, Garry G;

    2014-01-01

    The spindle assembly checkpoint (SAC) ensures accurate chromosome segregation by delaying entry into anaphase until all sister chromatids have become bi-oriented. A key component of the SAC is the Mad2 protein, which can adopt either an inactive open (O-Mad2) or active closed (C-Mad2) conformation...... in the SAC beyond recruitment of C-Mad2 to kinetochores has not yet been addressed. Here, we show that Mad1 is required for mitotic arrest even when C-Mad2 is artificially recruited to kinetochores, indicating that it has indeed an additional function in promoting the checkpoint. The C-terminal globular...

  10. Functional characterization of kinetochore protein, Ctf19 in meiosis I: an implication of differential impact of Ctf19 on the assembly of mitotic and meiotic kinetochores in Saccharomyces cerevisiae.

    Science.gov (United States)

    Mehta, Gunjan D; Agarwal, Meenakshi; Ghosh, Santanu K

    2014-03-01

    Meiosis is a specialized cell division process through which chromosome numbers are reduced by half for the generation of gametes. Kinetochore, a multiprotein complex that connects centromeres to microtubules, plays essential role in chromosome segregation. Ctf19 is the key central kinetochore protein that recruits all the other non-essential proteins of the Ctf19 complex in budding yeast. Earlier studies have shown the role of Ctf19 complex in enrichment of cohesin around the centromeres both during mitosis and meiosis, leading to sister chromatid cohesion and meiosis II disjunction. Here we show that Ctf19 is also essential for the proper execution of the meiosis I specific unique events, such as non-homologous centromere coupling, homologue pairing, chiasmata resolution and proper orientation of homologues and sister chromatids with respect to the spindle poles. Additionally, this investigation reveals that proper kinetochore function is required for faithful chromosome condensation in meiosis. Finally, this study suggests that absence of Ctf19 affects the integrity of meiotic kinetochore differently than that of the mitotic kinetochore. Consequently, absence of Ctf19 leads to gross chromosome missegregation during meiosis as compared with mitosis. Hence, this study reports for the first time the differential impact of a non-essential kinetochore protein on the mitotic and meiotic kinetochore ensembles and hence chromosome segregation.

  11. Mitotic Protein CSPP1 Interacts with CENP-H Protein to Coordinate Accurate Chromosome Oscillation in Mitosis.

    Science.gov (United States)

    Zhu, Lijuan; Wang, Zhikai; Wang, Wenwen; Wang, Chunli; Hua, Shasha; Su, Zeqi; Brako, Larry; Garcia-Barrio, Minerva; Ye, Mingliang; Wei, Xuan; Zou, Hanfa; Ding, Xia; Liu, Lifang; Liu, Xing; Yao, Xuebiao

    2015-11-06

    Mitotic chromosome segregation is orchestrated by the dynamic interaction of spindle microtubules with the kinetochores. During chromosome alignment, kinetochore-bound microtubules undergo dynamic cycles between growth and shrinkage, leading to an oscillatory movement of chromosomes along the spindle axis. Although kinetochore protein CENP-H serves as a molecular control of kinetochore-microtubule dynamics, the mechanistic link between CENP-H and kinetochore microtubules (kMT) has remained less characterized. Here, we show that CSPP1 is a kinetochore protein essential for accurate chromosome movements in mitosis. CSPP1 binds to CENP-H in vitro and in vivo. Suppression of CSPP1 perturbs proper mitotic progression and compromises the satisfaction of spindle assembly checkpoint. In addition, chromosome oscillation is greatly attenuated in CSPP1-depleted cells, similar to what was observed in the CENP-H-depleted cells. Importantly, CSPP1 depletion enhances velocity of kinetochore movement, and overexpression of CSPP1 decreases the speed, suggesting that CSPP1 promotes kMT stability during cell division. Specific perturbation of CENP-H/CSPP1 interaction using a membrane-permeable competing peptide resulted in a transient mitotic arrest and chromosome segregation defect. Based on these findings, we propose that CSPP1 cooperates with CENP-H on kinetochores to serve as a novel regulator of kMT dynamics for accurate chromosome segregation.

  12. Cyclin B1 is localized to unattached kinetochores and contributes to efficient microtubule attachment and proper chromosome alignment during mitosis

    Institute of Scientific and Technical Information of China (English)

    Qiang Chen; Xiaoyan Zhang; Qing Jiang; Paul R Clarke; Chuanmao Zhang

    2008-01-01

    Cyclin Bl is a key regulatory protein controlling cell cycle progression in vertebrates. Cyclin Bl binds CDK1, a cyclin-dependent kinase catalytic subunit, forming a complex that orchestrates mitosis through phosphorylation of key proteins. Cyclin Bl regulates both the activation of CDK1 and its subcellular localization, which may be critical for substrate selection. Here, we demonstrate that cyclin Bl is concentrated on the outer plate of the kinetochore during prometaphase. This localization requires the cyclin box region of the protein. Cyclin Bl is displaced from individual kinetochores to the spindle poles by microtubule attachment to the kinetochores, and this displacement is dependent on the dynein/dynactin complex. Depletion of cyclin Bl by vector-based siRNA causes inefficient attachment between kinetochores and microtubules, and chromosome alignment defects, and delays the onset of anaphase. We conclude that cyclin Bl accumulates at kinetochores during prometaphase, where it contributes to the correct attachment of microtubules to kinetochores and efficient alignment of the chromosomes, most likely through localized phosphorylation of specific substrates by cyclin B1-CDK1. Cyclin Bl is then transported from each kinetochore as microtubule attachment is completed, and this relocalization may redirect the activity of cyclin B1-CDK1 and contribute to inactivation of the spindle assembly checkpoint.

  13. Widespread Recurrent Patterns of Rapid Repeat Evolution in the Kinetochore Scaffold KNL1

    NARCIS (Netherlands)

    Tromer, Eelco; Snel, Berend; Kops, Geert J P L

    2015-01-01

    The outer kinetochore protein scaffold KNL1 is essential for error-free chromosome segregation during mitosis and meiosis. A critical feature of KNL1 is an array of repeats containing MELT-like motifs. When phosphorylated, these motifs form docking sites for the BUB1-BUB3 dimer that regulates chromo

  14. UV-C irradiation delays mitotic progression by recruiting Mps1 to kinetochores.

    Science.gov (United States)

    Zhang, Xiaojuan; Ling, Youguo; Wang, Wenjun; Zhang, Yanhong; Ma, Qingjun; Tan, Pingping; Song, Ting; Wei, Congwen; Li, Ping; Liu, Xuedong; Ma, Runlin Z; Zhong, Hui; Cao, Cheng; Xu, Quanbin

    2013-04-15

    The effect of UV irradiation on replicating cells during interphase has been studied extensively. However, how the mitotic cell responds to UV irradiation is less well defined. Herein, we found that UV-C irradiation (254 nm) increases recruitment of the spindle checkpoint proteins Mps1 and Mad2 to the kinetochore during metaphase, suggesting that the spindle assembly checkpoint (SAC) is reactivated. In accordance with this, cells exposed to UV-C showed delayed mitotic progression, characterized by a prolonged chromosomal alignment during metaphase. UV-C irradiation also induced the DNA damage response and caused a significant accumulation of γ-H2AX on mitotic chromosomes. Unexpectedly, the mitotic delay upon UV-C irradiation is not due to the DNA damage response but to the relocation of Mps1 to the kinetochore. Further, we found that UV-C irradiation activates Aurora B kinase. Importantly, the kinase activity of Aurora B is indispensable for full recruitment of Mps1 to the kinetochore during both prometaphase and metaphase. Taking these findings together, we propose that UV irradiation delays mitotic progression by evoking the Aurora B-Mps1 signaling cascade, which exerts its role through promoting the association of Mps1 with the kinetochore in metaphase.

  15. Auxin/AID versus conventional knockouts: distinguishing the roles of CENP-T/W in mitotic kinetochore assembly and stability.

    Science.gov (United States)

    Wood, Laura; Booth, Daniel G; Vargiu, Giulia; Ohta, Shinya; deLima Alves, Flavia; Samejima, Kumiko; Fukagawa, Tatsuo; Rappsilber, Juri; Earnshaw, William C

    2016-01-01

    Most studies using knockout technologies to examine protein function have relied either on shutting off transcription (conventional conditional knockouts with tetracycline-regulated gene expression or gene disruption) or destroying the mature mRNA (RNAi technology). In both cases, the target protein is lost at a rate determined by its intrinsic half-life. Thus, protein levels typically fall over at least 1-3 days, and cells continue to cycle while exposed to a decreasing concentration of the protein. Here we characterise the kinetochore proteome of mitotic chromosomes isolated from a cell line in which the essential kinetochore protein CENP-T is present as an auxin-inducible degron (AID) fusion protein that is fully functional and able to support the viability of the cells. Stripping of the protein from chromosomes in early mitosis via targeted proteasomal degradation reveals the dependency of other proteins on CENP-T for their maintenance in kinetochores. We compare these results with the kinetochore proteome of conventional CENP-T/W knockouts. As the cell cycle is mostly formed from G1, S and G2 phases a gradual loss of CENP-T/W levels is more likely to reflect dependencies associated with kinetochore assembly pre-mitosis and upon entry into mitosis. Interestingly, a putative super-complex involving Rod-Zw10-zwilch (RZZ complex), Spindly, Mad1/Mad2 and CENP-E requires the function of CENP-T/W during kinetochore assembly for its stable association with the outer kinetochore, but once assembled remains associated with chromosomes after stripping of CENP-T during mitosis. This study highlights the different roles core kinetochore components may play in the assembly of kinetochores (upon entry into mitosis) versus the maintenance of specific components (during mitosis).

  16. Small kinetochore associated protein (SKAP promotes UV-induced cell apoptosis through negatively regulating pre-mRNA processing factor 19 (Prp19.

    Directory of Open Access Journals (Sweden)

    Shan Lu

    Full Text Available Apoptosis is a regulated cellular suicide program that is critical for the development and maintenance of healthy tissues. Previous studies have shown that small kinetochore associated protein (SKAP cooperates with kinetochore and mitotic spindle proteins to regulate mitosis. However, the role of SKAP in apoptosis has not been investigated. We have identified a new interaction involving SKAP, and we propose a mechanism through which SKAP regulates cell apoptosis. Our experiments demonstrate that both overexpression and knockdown of SKAP sensitize cells to UV-induced apoptosis. Further study has revealed that SKAP interacts with Pre-mRNA processing Factor 19 (Prp19. We find that UV-induced apoptosis can be inhibited by ectopic expression of Prp19, whereas silencing Prp19 has the opposite effect. Additionally, SKAP negatively regulates the protein levels of Prp19, whereas Prp19 does not alter SKAP expression. Finally, rescue experiments demonstrate that the pro-apoptotic role of SKAP is executed through Prp19. Taken together, these findings suggest that SKAP promotes UV-induced cell apoptosis by negatively regulating the anti-apoptotic protein Prp19.

  17. Unique geometry of sister kinetochores in human oocytes during meiosis I may explain maternal age-associated increases in chromosomal abnormalities

    Directory of Open Access Journals (Sweden)

    Jessica Patel

    2016-02-01

    Full Text Available The first meiotic division in human oocytes is highly error-prone and contributes to the uniquely high incidence of aneuploidy observed in human pregnancies. A successful meiosis I (MI division entails separation of homologous chromosome pairs and co-segregation of sister chromatids. For this to happen, sister kinetochores must form attachments to spindle kinetochore-fibres emanating from the same pole. In mouse and budding yeast, sister kinetochores remain closely associated with each other during MI, enabling them to act as a single unified structure. However, whether this arrangement also applies in human meiosis I oocytes was unclear. In this study, we perform high-resolution imaging of over 1900 kinetochores in human oocytes, to examine the geometry and architecture of the human meiotic kinetochore. We reveal that sister kinetochores in MI are not physically fused, and instead individual kinetochores within a pair are capable of forming independent attachments to spindle k-fibres. Notably, with increasing female age, the separation between kinetochores increases, suggesting a degradation of centromeric cohesion and/or changes in kinetochore architecture. Our data suggest that the differential arrangement of sister kinetochores and dual k-fibre attachments may explain the high proportion of unstable attachments that form in MI and thus indicate why human oocytes are prone to aneuploidy, particularly with increasing maternal age.

  18. Unique geometry of sister kinetochores in human oocytes during meiosis I may explain maternal age-associated increases in chromosomal abnormalities.

    Science.gov (United States)

    Patel, Jessica; Tan, Seang Lin; Hartshorne, Geraldine M; McAinsh, Andrew D

    2015-12-30

    The first meiotic division in human oocytes is highly error-prone and contributes to the uniquely high incidence of aneuploidy observed in human pregnancies. A successful meiosis I (MI) division entails separation of homologous chromosome pairs and co-segregation of sister chromatids. For this to happen, sister kinetochores must form attachments to spindle kinetochore-fibres emanating from the same pole. In mouse and budding yeast, sister kinetochores remain closely associated with each other during MI, enabling them to act as a single unified structure. However, whether this arrangement also applies in human meiosis I oocytes was unclear. In this study, we perform high-resolution imaging of over 1900 kinetochores in human oocytes, to examine the geometry and architecture of the human meiotic kinetochore. We reveal that sister kinetochores in MI are not physically fused, and instead individual kinetochores within a pair are capable of forming independent attachments to spindle k-fibres. Notably, with increasing female age, the separation between kinetochores increases, suggesting a degradation of centromeric cohesion and/or changes in kinetochore architecture. Our data suggest that the differential arrangement of sister kinetochores and dual k-fibre attachments may explain the high proportion of unstable attachments that form in MI and thus indicate why human oocytes are prone to aneuploidy, particularly with increasing maternal age.

  19. Push or Pull? -- Cryo-Electron Microscopy of Microtubule's Dynamic Instability and Its Roles in the Kinetochore

    Science.gov (United States)

    Wang, Hong-Wei

    2009-03-01

    Microtubule is a biopolymer made up of alpha-beta-tubulin heterodimers. The tubulin dimers assemble head-to-tail as protofilaments and about 13 protofilaments interact laterally to form a hollow cylindrical structure which is the microtubule. As the major cytoskeleton in all eukaryotic cells, microtubules have the intrinsic property to switch stochastically between growth and shrinkage phases, a phenomenon termed as their dynamic instability. Microtubule's dynamic instability is closely related to the types of nucleotide (GTP or GDP) that binds to the beta-tubulin. We have biochemically trapped two types of assembly states of tubulin with GTP or GDP bound representing the polymerizing and depolymerizing ends of microtubules respectively. Using cryo-electron microscopy, we have elucidated the structures of these intermediate assemblies, showing that tubulin protofilaments demonstrate various curvatures and form different types of lateral interactions depending on the nucleotide states of tubulin and the temperature. Our work indicates that during the microtubule's dynamic cycle, tubulin undergoes various assembly states. These states, different from the straight microtubule, lend the highly dynamic and complicated behavior of microtubules. Our study of microtubule's interaction with certain kinetochore complexes suggests that the intermediate assemblies are responsible for specific mechanical forces that are required during the mitosis or meiosis. Our discoveries strongly suggest that a microtubule is a molecular machine rather than a simple cellular scaffold.

  20. Mitosin/CENP-F is a conserved kinetochore protein subjected to cytoplasmic dynein-mediated poleward transport

    Institute of Scientific and Technical Information of China (English)

    ZHEN YE YANG; JING GUO; NING LI; MIN QIAN; SHENG NIAN WANG; XUE LIANG ZHU

    2003-01-01

    Mitosin/CENP-F is a human nuclear protein transiently associated with the outer kinetochore plate in M phase and is involved in M phase progression. LEK1 and CMF1, which are its murine and chicken orthologs, however, are implicated in muscle differentiation and reportedly not distributed at kinetochores.We therefore conducted several assays to clarify this issue. The typical centromere staining patterns were observed in mitotic cells from both human primary culture and murine, canine, and mink cell lines. A C-terminal portion of LEK1 also conferred centromere localization. Our analysis further suggests conserved kinetochore localization of mammalian mitosin orthologs. Moreover, mitosin was associated preferentially with kinetochores of unaligned chromosomes. It was also constantly transported from kinetochores to spindle poles by cytoplasmic dynein. These properties resemble those of other kinetochore proteins important for the spindle checkpoint, thus implying a role of mitosin in this checkpoint. Therefore, mitosin family may serve as multifunctional proteins involved in both mitosis and differentiation.

  1. Complete kinetochore tracking reveals error-prone homologous chromosome biorientation in mammalian oocytes.

    Science.gov (United States)

    Kitajima, Tomoya S; Ohsugi, Miho; Ellenberg, Jan

    2011-08-19

    Chromosomes must establish stable biorientation prior to anaphase to achieve faithful segregation during cell division. The detailed process by which chromosomes are bioriented and how biorientation is coordinated with spindle assembly and chromosome congression remain unclear. Here, we provide complete 3D kinetochore-tracking datasets throughout cell division by high-resolution imaging of meiosis I in live mouse oocytes. We show that in acentrosomal oocytes, chromosome congression forms an intermediate chromosome configuration, the prometaphase belt, which precedes biorientation. Chromosomes then invade the elongating spindle center to form the metaphase plate and start biorienting. Close to 90% of all chromosomes undergo one or more rounds of error correction of their kinetochore-microtubule attachments before achieving correct biorientation. This process depends on Aurora kinase activity. Our analysis reveals the error-prone nature of homologous chromosome biorientation, providing a possible explanation for the high incidence of aneuploid eggs observed in mammals, including humans.

  2. Chromosome Bridges Maintain Kinetochore-Microtubule Attachment throughout Mitosis and Rarely Break during Anaphase.

    Directory of Open Access Journals (Sweden)

    Judit Pampalona

    Full Text Available Accurate chromosome segregation during cell division is essential to maintain genome stability, and chromosome segregation errors are causally linked to genetic disorders and cancer. An anaphase chromosome bridge is a particular chromosome segregation error observed in cells that enter mitosis with fused chromosomes/sister chromatids. The widely accepted Breakage/Fusion/Bridge cycle model proposes that anaphase chromosome bridges break during mitosis to generate chromosome ends that will fuse during the following cell cycle, thus forming new bridges that will break, and so on. However, various studies have also shown a link between chromosome bridges and aneuploidy and/or polyploidy. In this study, we investigated the behavior and properties of chromosome bridges during mitosis, with the idea to gain insight into the potential mechanism underlying chromosome bridge-induced aneuploidy. We find that only a small number of chromosome bridges break during anaphase, whereas the rest persist through mitosis into the subsequent cell cycle. We also find that the microtubule bundles (k-fibers bound to bridge kinetochores are not prone to breakage/detachment, thus supporting the conclusion that k-fiber detachment is not the cause of chromosome bridge-induced aneuploidy. Instead, our data suggest that while the microtubules bound to the kinetochores of normally segregating chromosomes shorten substantially during anaphase, the k-fibers bound to bridge kinetochores shorten only slightly, and may even lengthen, during anaphase. This causes some of the bridge kinetochores/chromosomes to lag behind in a position that is proximal to the cell/spindle equator and may cause the bridged chromosomes to be segregated into the same daughter nucleus or to form a micronucleus.

  3. Chromosome Bridges Maintain Kinetochore-Microtubule Attachment throughout Mitosis and Rarely Break during Anaphase.

    Science.gov (United States)

    Pampalona, Judit; Roscioli, Emanuele; Silkworth, William T; Bowden, Brent; Genescà, Anna; Tusell, Laura; Cimini, Daniela

    2016-01-01

    Accurate chromosome segregation during cell division is essential to maintain genome stability, and chromosome segregation errors are causally linked to genetic disorders and cancer. An anaphase chromosome bridge is a particular chromosome segregation error observed in cells that enter mitosis with fused chromosomes/sister chromatids. The widely accepted Breakage/Fusion/Bridge cycle model proposes that anaphase chromosome bridges break during mitosis to generate chromosome ends that will fuse during the following cell cycle, thus forming new bridges that will break, and so on. However, various studies have also shown a link between chromosome bridges and aneuploidy and/or polyploidy. In this study, we investigated the behavior and properties of chromosome bridges during mitosis, with the idea to gain insight into the potential mechanism underlying chromosome bridge-induced aneuploidy. We find that only a small number of chromosome bridges break during anaphase, whereas the rest persist through mitosis into the subsequent cell cycle. We also find that the microtubule bundles (k-fibers) bound to bridge kinetochores are not prone to breakage/detachment, thus supporting the conclusion that k-fiber detachment is not the cause of chromosome bridge-induced aneuploidy. Instead, our data suggest that while the microtubules bound to the kinetochores of normally segregating chromosomes shorten substantially during anaphase, the k-fibers bound to bridge kinetochores shorten only slightly, and may even lengthen, during anaphase. This causes some of the bridge kinetochores/chromosomes to lag behind in a position that is proximal to the cell/spindle equator and may cause the bridged chromosomes to be segregated into the same daughter nucleus or to form a micronucleus.

  4. Role of Intrinsic and Extrinsic Factors in the Regulation of the Mitotic Checkpoint Kinase Bub1.

    Directory of Open Access Journals (Sweden)

    Claudia Breit

    Full Text Available The spindle assembly checkpoint (SAC monitors microtubule attachment to kinetochores to ensure accurate sister chromatid segregation during mitosis. The SAC members Bub1 and BubR1 are paralogs that underwent significant functional specializations during evolution. We report an in-depth characterization of the kinase domains of Bub1 and BubR1. BubR1 kinase domain binds nucleotides but is unable to deliver catalytic activity in vitro. Conversely, Bub1 is an active kinase regulated by intra-molecular phosphorylation at the P+1 loop. The crystal structure of the phosphorylated Bub1 kinase domain illustrates a hitherto unknown conformation of the P+1 loop docked into the active site of the Bub1 kinase. Both Bub1 and BubR1 bind Bub3 constitutively. A hydrodynamic characterization of Bub1:Bub3 and BubR1:Bub3 demonstrates both complexes to have 1:1 stoichiometry, with no additional oligomerization. Conversely, Bub1:Bub3 and BubR1:Bub3 combine to form a heterotetramer. Neither BubR1:Bub3 nor Knl1, the kinetochore receptor of Bub1:Bub3, modulate the kinase activity of Bub1 in vitro, suggesting autonomous regulation of the Bub1 kinase domain. We complement our study with an analysis of the Bub1 substrates. Our results contribute to the mechanistic characterization of a crucial cell cycle checkpoint.

  5. Chk2 prevents mitotic exit when the majority of kinetochores are unattached.

    Science.gov (United States)

    Petsalaki, Eleni; Zachos, George

    2014-05-12

    The spindle checkpoint delays exit from mitosis in cells with spindle defects. In this paper, we show that Chk2 is required to delay anaphase onset when microtubules are completely depolymerized but not in the presence of relatively few unattached kinetochores. Mitotic exit in Chk2-deficient cells correlates with reduced levels of Mps1 protein and increased Cdk1-tyrosine 15 inhibitory phosphorylation. Chk2 localizes to kinetochores and is also required for Aurora B-serine 331 phosphorylation in nocodazole or unperturbed early prometaphase. Serine 331 phosphorylation contributed to prometaphase accumulation in nocodazole after partial Mps1 inhibition and was required for spindle checkpoint establishment at the beginning of mitosis. In addition, expression of a phosphomimetic S331E mutant Aurora B rescued chromosome alignment or segregation in Chk2-deficient cells. We propose that Chk2 stabilizes Mps1 and phosphorylates Aurora B-serine 331 to prevent mitotic exit when most kinetochores are unattached. These results highlight mechanisms of an essential function of Chk2 in mitosis.

  6. CDK-1 Inhibition in G2 Stabilizes Kinetochore-Microtubules in the following Mitosis.

    Science.gov (United States)

    Gayek, A Sophia; Ohi, Ryoma

    2016-01-01

    Cell proliferation is driven by cyclical activation of cyclin-dependent kinases (CDKs), which produce distinct biochemical cell cycle phases. Mitosis (M phase) is orchestrated by CDK-1, complexed with mitotic cyclins. During M phase, chromosomes are segregated by a bipolar array of microtubules called the mitotic spindle. The essential bipolarity of the mitotic spindle is established by the kinesin-5 Eg5, but factors influencing the maintenance of spindle bipolarity are not fully understood. Here, we describe an unexpected link between inhibiting CDK-1 before mitosis and bipolar spindle maintenance. Spindles in human RPE-1 cells normally collapse to monopolar structures when Eg5 is inhibited at metaphase. However, we found that inhibition of CDK-1 in the G2 phase of the cell cycle improved the ability of RPE-1 cells to maintain spindle bipolarity without Eg5 activity in the mitosis immediately after release from CDK-1 inhibition. This improved bipolarity maintenance correlated with an increase in the stability of kinetochore-microtubules, the subset of microtubules that link chromosomes to the spindle. The improvement in bipolarity maintenance after CDK-1 inhibition in G2 required both the kinesin-12 Kif15 and increased stability of kinetochore-microtubules. Consistent with increased kinetochore-microtubule stability, we find that inhibition of CDK-1 in G2 impairs mitotic fidelity by increasing the incidence of lagging chromosomes in anaphase. These results suggest that inhibition of CDK-1 in G2 causes unpredicted effects in mitosis, even after CDK-1 inhibition is relieved.

  7. The requirement for the Dam1 complex is dependent upon the number of kinetochore proteins and microtubules.

    Science.gov (United States)

    Burrack, Laura S; Applen, Shelly E; Berman, Judith

    2011-05-24

    The Dam1 complex attaches the kinetochore to spindle microtubules and is a processivity factor in vitro. In Saccharomyces cerevisiae, which has point centromeres that attach to a single microtubule, deletion of any Dam1 complex member results in chromosome segregation failures and cell death. In Schizosaccharomyces pombe, which has epigenetically defined regional centromeres that each attach to 3-5 kinetochore microtubules, Dam1 complex homologs are not essential. To determine why the complex is essential in some organisms and not in others, we used Candida albicans, a multimorphic yeast with regional centromeres that attach to a single microtubule. Interestingly, the Dam1 complex was essential in C. albicans, suggesting that the number of microtubules per centromere is critical for its requirement. Importantly, by increasing CENP-A expression levels, more kinetochore proteins and microtubules were recruited to the centromeres, which remained fully functional. Furthermore, Dam1 complex members became less crucial for growth in cells with extra kinetochore proteins and microtubules. Thus, the requirement for the Dam1 complex is not due to the DNA-specific nature of point centromeres. Rather, the Dam1 complex is less critical when chromosomes have multiple kinetochore complexes and microtubules per centromere, implying that it functions as a processivity factor in vivo as well as in vitro.

  8. Zwint-1 is required for spindle assembly checkpoint function and kinetochore-microtubule attachment during oocyte meiosis.

    Science.gov (United States)

    Woo Seo, Dong; Yeop You, Seung; Chung, Woo-Jae; Cho, Dong-Hyung; Kim, Jae-Sung; Su Oh, Jeong

    2015-10-21

    The key step for faithful chromosome segregation during meiosis is kinetochore assembly. Defects in this process result in aneuploidy, leading to miscarriages, infertility and various birth defects. However, the roles of kinetochores in homologous chromosome segregation during meiosis are ill-defined. Here we found that Zwint-1 is required for homologous chromosome segregation during meiosis. Knockdown of Zwint-1 accelerated the first meiosis by abrogating the kinetochore recruitment of Mad2, leading to chromosome misalignment and a high incidence of aneuploidy. Although Zwint-1 knockdown did not affect Aurora C kinase activity, the meiotic defects following Zwint-1 knockdown were similar to those observed with ZM447439 treatment. Importantly, the chromosome misalignment following Aurora C kinase inhibition was not restored after removing the inhibitor in Zwint-1-knockdown oocytes, whereas the defect was rescued after the inhibitor washout in the control oocytes. These results suggest that Aurora C kinase-mediated correction of erroneous kinetochore-microtubule attachment is primarily regulated by Zwint-1. Our results provide the first evidence that Zwint-1 is required to correct erroneous kinetochore-microtubule attachment and regulate spindle checkpoint function during meiosis.

  9. Overexpression of the dynein light chain km23-1 in human ovarian carcinoma cells inhibits tumor formation in vivo and causes mitotic delay at prometaphase/metaphase.

    Science.gov (United States)

    Pulipati, Nageswara R; Jin, Qunyan; Liu, Xin; Sun, Baodong; Pandey, Manoj K; Huber, Jonathan P; Ding, Wei; Mulder, Kathleen M

    2011-08-01

    km23-1 is a dynein light chain that was identified as a TGFβ receptor-interacting protein. To investigate whether km23-1 controls human ovarian carcinoma cell (HOCC) growth, we established a tet-off inducible expression system in SKOV-3 cells in which the expression of km23-1 is induced upon doxycycline removal. We found that forced expression of km23-1 inhibited both anchorage-dependent and anchorage-independent growth of SKOV-3 cells. More importantly, induction of km23-1 expression substantially reduced the tumorigenicity of SKOV-3 cells in a xenograft model in vivo. Fluorescence-activated cell sorting analysis of SKOV-3 and IGROV-1 HOCCs demonstrated that the cells were accumulating at G2/M. Phospho-MEK, phospho-ERK and cyclin B1 were elevated, as was the mitotic index, suggesting that km23-1 suppresses HOCCs growth by inducing a mitotic delay. Immunofluorescence analyses demonstrated that the cells were accumulating at prometaphase/metaphase with increases in multipolar and multinucleated cells. Further, although the mitotic spindle assembly checkpoint protein BubR1 was present at the prometaphase kinetochore in Dox+/- cells, it was inappropriately retained at the metaphase kinetochore in Dox- cells. Thus, the mechanism by which high levels of km23-1 suppress ovarian carcinoma growth in vitro and inhibit ovary tumor formation in vivo appears to involve a BubR1-related mitotic delay.

  10. Kinetochore–microtubule error correction is driven by differentially regulated interaction modes

    OpenAIRE

    Kalantzaki, Maria; Kitamura, Etsushi; Zhang, Tongli; Mino, Akihisa; Novák, Béla; Tanaka, Tomoyuki U

    2015-01-01

    For proper chromosome segregation, sister kinetochores must interact with microtubules from opposite spindle poles (bi-orientation). To establish bi-orientation, aberrant kinetochore–microtubule attachments are disrupted (error correction) by Aurora B kinase (Ipl1 in budding yeast). Paradoxically, during this disruption, new attachments are still formed efficiently to allow fresh attempts at bi-orientation. How this is possible remains an enigma. Here we show that kinetochore attachment to th...

  11. Validate Mitotic Checkpoint and Kinetochore Motor Proteins in Breast Cancer Cells as Targets for the Development of Novel Anti-Mitotic Drugs

    Science.gov (United States)

    2005-07-01

    of the Human Kinetochore Protein CENP-E Isabel Garcia-Saez’, Tim Yen 2, Richard H. Wade’ and Frank Kozielskil* ’Laboratoire de Microscopic The human...kinetochore is a highly complex macromolecular structure Electronique Structurale that connects chromosomes to spindle microtubules (MTs) in order to

  12. A theoretical model for attachment lifetimes of kinetochore-microtubules: Mechano-kinetic "catch-bond" mechanism for error-correction

    CERN Document Server

    Shtylla, Blerta

    2013-01-01

    Before cell division, two identical copies of chromosomes are pulled apart by microtubule (MT) filaments that approach the chromosomes from the opposite poles a mitotic spindle. Connection between the MTs and the chromosomes are mediated by a molecular complex called kinetochore. An externally applied tension can lead to detachment of the MTs from the kinetochore; the mean lifetime of such an attachment is essentially a mean first-passage time. In their in-vitro pioneering single-kinetochore experiments, Akiyoshi et al. (Nature 468, 576 (2010)), observed that the mean lifetimes of reconstituted MT-kinetochore attachments vary non-monotonically with increasing tension. The counter-intuitive stabilization of the attachments by small load forces was interpreted in terms of a catch-bond-like mechanism based on a phenomenological 2-state kinetic model. Here we develop the first detailed microscopic model for studying the dependence of the lifetime of the MT-kinetochore attachment on (a) the structure, (b) energeti...

  13. An extended corona attached to metaphase kinetochores of the green alga Oedogonium.

    Science.gov (United States)

    Pickett-Heaps, J D; Carpenter, J

    1993-04-01

    Mitotic cells of the green alga Oedogonium were treated with the anti-microtubule agent oryzalin (1.0-0.1 microM) for 5 to 10 min. Within 5 min treatment of living cells, metaphase spindles became spherical with disorganized chromosomes, and anaphase spindles collapsed. At lower concentrations, the effects were slower, and partial recovery was observed about 10 to 20 min after the drug was washed out. Following breakdown of the spindle, considerable disorganized activity detected by time-lapse continued within the nucleus, isolated from the cytoplasm by its intact nuclear membrane. Under the electron microscope, spindle microtubules (MTs) were absent in oryzalin-treated cells. Paired metaphase kinetochores displayed an array of fine filamentous material extended, usually straight, about 3 microns into the nucleoplasm. In cells recovering from oryzalin treatment, MTs became associated with kinetochores in the usual manner. However, this filamentous array, the "extended corona" (EC), was almost undetectable, even when the MTs were short and poorly organized. The EC is appreciably larger by metaphase than the corona of prophase chromosomes and so it may assemble during early mitosis. Fine filaments interspersed with kinetochore MTs have been described in carefully fixed cells of this alga (M.J. Schibler, J.D. Pickett-Heaps, Eur. J. Cell Biol. 22, 687-698 (1980)). The EC apparently represents a less organized form of this material remaining after its scaffold of MTs has been removed. These fibers appear involved in MT capture upon spindle recovery from anti-MT drugs. They could function during prometaphase and even anaphase movement along spindle MTs.

  14. Theory of dynamic force spectroscopy for kinetochore-microtubule attachments: rupture force distribution

    CERN Document Server

    Ghanti, Dipanwita

    2016-01-01

    Application of pulling force, under force-clamp conditions, to kinetochore-microtubule attachments {\\it in-vitro} revealed a catch-bond-like behavior. In an earlier paper ({\\it Sharma et al. Phys. Biol. (2014)} the physical origin of this apparently counter-intuitive phenomenon was traced to the nature of the force-dependence of the (de-)polymerization kinetics of the microtubules. In this brief communication that work is extended to situations where the external forced is ramped up till the attachment gets ruptured. In spite of the fundamental differences in the underlying mechanisms, the trend of variation of the rupture force distribution observed in our model kinetochore-microtubule attachment with the increasing loading rate is qualitatively similar to that displayed by the catch bonds formed in some other ligand-receptor systems. Our theoretical predictions can be tested experimentally by a straightforward modification of the protocol for controlling the force in the optical trap set up that was used in...

  15. Effects of sense and antisense centromere/kinetochore complex protein-B (CENP-B) in cell cycle regulation

    Institute of Scientific and Technical Information of China (English)

    LUO Song; LIN Haiyan; QI Jianguo; WANG Yongchao

    2005-01-01

    This paper investigates the effects of sense and antisense centromere/kinetochore complex protein-B (CENP-B) in cell cycle regulation. Full-length cenpb cDNA was subcloned into pBI-EGFP eukaryotic expression vector in both sense and antisense orientation. HeLa-Tet-Off cells were transfected with sense or antisense cenpb vectors. Sense transfection of HeLa-Tet-Off cells resulted in the formation of a large centromere/kinetochore complex, and apoptosis of cells following several times of cell division. A stable antisense cenpb transfected cell line, named HACPB, was obtained. The centromere/kinetochore complex of HACPB cells became smaller than control HeLa-Tet-Off cells and scattered, and the expression of CENP-B was down-regulated. In addition, delayed cell cycle progression, inhibited malignant phenotype, restrained ability of tumor formation in nude mice, and delayed entry from G2/M phase into next G1 phase were observed in HACPB cells. Furthermore, the expression of cyclin-dependent kinases (CDKs), cyclins, and CDK inhibitors (CKIs) were modulated during different phases of the cell cycle. CENP-B is an essential protein for the maintenance of the structure and function of centromere/kinetochore complex, and plays important roles in cell cycle regulation.

  16. Novel subcellular localization of the DNA helicase Twinkle at the kinetochore complex during mitosis in neuronal-like progenitor cells.

    Science.gov (United States)

    Uittenbogaard, Martine; Chiaramello, Anne

    2016-03-01

    During mitosis, the kinetochore, a multi-protein structure located on the centromeric DNA, is responsible for proper segregation of the replicated genome. More specifically, the outer kinetochore complex component Ndc80/Hec1 plays a critical role in regulating microtubule attachment to the spindle for accurate sister chromatid segregation. In addition, DNA helicases play a key contribution for precise and complete disjunction of sister chromatids held together through double-stranded DNA catenations until anaphase. In this study, we focused our attention on the nuclear-encoded DNA helicase Twinkle, which functions as an essential helicase for replication of mitochondrial DNA. It regulates the copy number of the mitochondrial genome, while maintaining its integrity, two processes essential for mitochondrial biogenesis and bioenergetic functions. Although the majority of the Twinkle protein is imported into mitochondria, a small fraction remains cytosolic with an unknown function. In this study, we report a novel expression pattern of Twinkle during chromosomal segregation at distinct mitotic phases. By immunofluorescence microscopy, we found that Twinkle protein colocalizes with the outer kinetochore protein HEC1 as early as prophase until late anaphase in neuronal-like progenitor cells. Thus, our collective results have revealed an unexpected cell cycle-regulated expression pattern of the DNA helicase Twinkle, known for its role in mtDNA replication. Therefore, its recruitment to the kinetochore suggests an evolutionary conserved function for both mitochondrial and nuclear genomic inheritance.

  17. 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.

  18. Phallacidin stains the kinetochore region in the mitotic spindle of the green algae Oedogonium spp.

    Science.gov (United States)

    Sampson, K; Pickett-Heaps, J D

    2001-01-01

    We found previously that in living cells of Oedogonium cardiacum and O. donnellii, mitosis is blocked by the drug cytochalasin D (CD). We now report on the staining observed in these spindles with fluorescently actin-labeling reagents, particularly Bodipy FL phallacidin. Normal mitotic cells exhibited spots of staining associated with chromosomes; frequently the spots appeared in pairs during prometaphase-metaphase. During later anaphase and telophase, the staining was confined to the region between chromosomes and poles. The texture of the staining appeared to be somewhat dispersed by CD treatment but it was still present, particularly after shorter (Oedogonium spp. The previous observations on living cells suggest that it is a functional component of the kinetochore-MT complex involved in the correct attachment of chromosomes to the spindle.

  19. The crystal structure of the Sgt1-Skp1 complex: the link between Hsp90 and both SCF E3 ubiquitin ligases and kinetochores

    Science.gov (United States)

    Willhoft, Oliver; Kerr, Richard; Patel, Dipali; Zhang, Wenjuan; Al-Jassar, Caezar; Daviter, Tina; Millson, Stefan H.; Thalassinos, Konstantinos; Vaughan, Cara K.

    2017-01-01

    The essential cochaperone Sgt1 recruits Hsp90 chaperone activity to a range of cellular factors including SCF E3 ubiquitin ligases and the kinetochore in eukaryotes. In these pathways Sgt1 interacts with Skp1, a small protein that heterodimerizes with proteins containing the F-box motif. We have determined the crystal structure of the interacting domains of Saccharomyces cerevisiae Sgt1 and Skp1 at 2.8 Å resolution and validated the interface in the context of the full-length proteins in solution. The BTB/POZ domain of Skp1 associates with Sgt1 via the concave surface of its TPR domain using residues that are conserved in humans. Dimerization of yeast Sgt1 occurs via an insertion that is absent from monomeric human Sgt1. We identify point mutations that disrupt dimerization and Skp1 binding in vitro and find that the interaction with Skp1 is an essential function of Sgt1 in yeast. Our data provide a structural rationale for understanding the phenotypes of temperature-sensitive Sgt1 mutants and for linking Skp1-associated proteins to Hsp90-dependent pathways. PMID:28139700

  20. Reduced ability to recover from spindle disruption and loss of kinetochore spindle assembly checkpoint proteins in oocytes from aged mice.

    Science.gov (United States)

    Yun, Yan; Holt, Janet E; Lane, Simon I R; McLaughlin, Eileen A; Merriman, Julie A; Jones, Keith T

    2014-01-01

    Currently, maternal aging in women, based on mouse models, is thought to raise oocyte aneuploidy rates, because chromosome cohesion deteriorates during prophase arrest, and Sgo2, a protector of centromeric cohesion, is lost. Here we show that the most common mouse strain, C57Bl6/J, is resistant to maternal aging, showing little increase in aneuploidy or Sgo2 loss. Instead it demonstrates significant kinetochore-associated loss in the spindle assembly checkpoint protein Mad2 and phosphorylated Aurora C, which is involved in microtubule-kinetochore error correction. Their loss affects the fidelity of bivalent segregation but only when spindle organization is impaired during oocyte maturation. These findings have an impact clinically regarding the handling of human oocytes ex vivo during assisted reproductive techniques and suggest there is a genetic basis to aneuploidy susceptibility.

  1. A minimal number of MELT repeats supports all functions of KNL1 in chromosome segregation

    DEFF Research Database (Denmark)

    Zhang, Gang; Lischetti, Tiziana; Nilsson, Jakob

    2013-01-01

    The Bub1-Bub3 and BubR1-Bub3 checkpoint complexes, or the Bubs, contribute to the accurate segregation of chromosomes during mitosis by promoting chromosome bi-orientation and halting exit from mitosis if this fails. The complexes associate with kinetochores during mitosis, which is required...

  2. STAG2 promotes error correction in mitosis by regulating kinetochore-microtubule attachments.

    Science.gov (United States)

    Kleyman, Marianna; Kabeche, Lilian; Compton, Duane A

    2014-10-01

    Mutations in the STAG2 gene are present in ∼20% of tumors from different tissues of origin. STAG2 encodes a subunit of the cohesin complex, and tumors with loss-of-function mutations are usually aneuploid and display elevated frequencies of lagging chromosomes during anaphase. Lagging chromosomes are a hallmark of chromosomal instability (CIN) arising from persistent errors in kinetochore-microtubule (kMT) attachment. To determine whether the loss of STAG2 increases the rate of formation of kMT attachment errors or decreases the rate of their correction, we examined mitosis in STAG2-deficient cells. STAG2 depletion does not impair bipolar spindle formation or delay mitotic progression. Instead, loss of STAG2 permits excessive centromere stretch along with hyperstabilization of kMT attachments. STAG2-deficient cells display mislocalization of Bub1 kinase, Bub3 and the chromosome passenger complex. Importantly, strategically destabilizing kMT attachments in tumor cells harboring STAG2 mutations by overexpression of the microtubule-destabilizing enzymes MCAK (also known as KIF2C) and Kif2B decreased the rate of lagging chromosomes and reduced the rate of chromosome missegregation. These data demonstrate that STAG2 promotes the correction of kMT attachment errors to ensure faithful chromosome segregation during mitosis.

  3. Human papillomavirus type 16 E7 oncoprotein engages but does not abrogate the mitotic spindle assembly checkpoint

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yueyang [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States); Munger, Karl, E-mail: kmunger@rics.bwh.harvard.edu [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States)

    2012-10-10

    The mitotic spindle assembly checkpoint (SAC) ensures faithful chromosome segregation during mitosis by censoring kinetochore-microtubule interactions. It is frequently rendered dysfunctional during carcinogenesis causing chromosome missegregation and genomic instability. There are conflicting reports whether the HPV16 E7 oncoprotein drives chromosomal instability by abolishing the SAC. Here we report that degradation of mitotic cyclins is impaired in cells with HPV16 E7 expression. RNAi-mediated depletion of Mad2 or BubR1 indicated the involvement of the SAC, suggesting that HPV16 E7 expression causes sustained SAC engagement. Mutational analyses revealed that HPV16 E7 sequences that are necessary for retinoblastoma tumor suppressor protein binding as well as sequences previously implicated in binding the nuclear and mitotic apparatus (NuMA) protein and in delocalizing dynein from the mitotic spindle contribute to SAC engagement. Importantly, however, HPV16 E7 does not markedly compromise the SAC response to microtubule poisons.

  4. MAPK-activated protein kinase 2 is required for mouse meiotic spindle assembly and kinetochore-microtubule attachment.

    Directory of Open Access Journals (Sweden)

    Ju Yuan

    Full Text Available MAPK-activated protein kinase 2 (MK2, a direct substrate of p38 MAPK, plays key roles in multiple physiological functions in mitosis. Here, we show for the first time the unique distribution pattern of MK2 in meiosis. Phospho-MK2 was localized on bipolar spindle minus ends and along the interstitial axes of homologous chromosomes extending over centromere regions and arm regions at metaphase of first meiosis (MI stage in mouse oocytes. At metaphase of second meiosis (MII stage, p-MK2 was localized on the bipolar spindle minus ends and at the inner centromere region of sister chromatids as dots. Knockdown or inhibition of MK2 resulted in spindle defects. Spindles were surrounded by irregular nondisjunction chromosomes, which were arranged in an amphitelic or syntelic/monotelic manner, or chromosomes detached from the spindles. Kinetochore-microtubule attachments were impaired in MK2-deficient oocytes because spindle microtubules became unstable in response to cold treatment. In addition, homologous chromosome segregation and meiosis progression were inhibited in these oocytes. Our data suggest that MK2 may be essential for functional meiotic bipolar spindle formation, chromosome segregation and proper kinetochore-microtubule attachments.

  5. Modular elements of the TPR domain in the Mps1 N terminus differentially target Mps1 to the centrosome and kinetochore.

    Science.gov (United States)

    Marquardt, Joseph R; Perkins, Jennifer L; Beuoy, Kyle J; Fisk, Harold A

    2016-07-12

    Faithful segregation of chromosomes to two daughter cells is regulated by the formation of a bipolar mitotic spindle and the spindle assembly checkpoint, ensuring proper spindle function. Here we show that the proper localization of the kinase Mps1 (monopolar spindle 1) is critical to both these processes. Separate elements in the Mps1 N-terminal extension (NTE) and tetratricopeptide repeat (TPR) domains govern localization to either the kinetochore or the centrosome. The third TPR (TPR3) and the TPR-capping helix (C-helix) are each sufficient to target Mps1 to the centrosome. TPR3 binds to voltage-dependent anion channel 3, but although this is sufficient for centrosome targeting of Mps1, it is not necessary because of the presence of the C-helix. A version of Mps1 lacking both elements cannot localize to or function at the centrosome, but maintains kinetochore localization and spindle assembly checkpoint function, indicating that TPR3 and the C-helix define a bipartite localization determinant that is both necessary and sufficient to target Mps1 to the centrosome but dispensable for kinetochore targeting. In contrast, elements required for kinetochore targeting (the NTE and first two TPRs) are dispensable for centrosomal localization and function. These data are consistent with a separation of Mps1 function based on localization determinants within the N terminus.

  6. A TPR domain-containing N-terminal module of MPS1 is required for its kinetochore localization by Aurora B.

    Science.gov (United States)

    Nijenhuis, Wilco; von Castelmur, Eleonore; Littler, Dene; De Marco, Valeria; Tromer, Eelco; Vleugel, Mathijs; van Osch, Maria H J; Snel, Berend; Perrakis, Anastassis; Kops, Geert J P L

    2013-04-15

    The mitotic checkpoint ensures correct chromosome segregation by delaying cell cycle progression until all kinetochores have attached to the mitotic spindle. In this paper, we show that the mitotic checkpoint kinase MPS1 contains an N-terminal localization module, organized in an N-terminal extension (NTE) and a tetratricopeptide repeat (TPR) domain, for which we have determined the crystal structure. Although the module was necessary for kinetochore localization of MPS1 and essential for the mitotic checkpoint, the predominant kinetochore binding activity resided within the NTE. MPS1 localization further required HEC1 and Aurora B activity. We show that MPS1 localization to kinetochores depended on the calponin homology domain of HEC1 but not on Aurora B-dependent phosphorylation of the HEC1 tail. Rather, the TPR domain was the critical mediator of Aurora B control over MPS1 localization, as its deletion rendered MPS1 localization insensitive to Aurora B inhibition. These data are consistent with a model in which Aurora B activity relieves a TPR-dependent inhibitory constraint on MPS1 localization.

  7. Heterogeneous nuclear ribonucleoprotein K upregulates the kinetochore complex component NUF2 and promotes the tumorigenicity of colon cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Sugimasa, Hironobu; Taniue, Kenzui [Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032 (Japan); Kurimoto, Akiko [Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032 (Japan); Oncology Research Laboratories, Daiichi Sankyo Co., Ltd, 1-2-58, Hiromachi, Shinagawa-ku, Tokyo, 140-8710 (Japan); Takeda, Yasuko; Kawasaki, Yoshihiro [Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032 (Japan); Akiyama, Tetsu, E-mail: akiyama@iam.u-tokyo.ac.jp [Laboratory of Molecular and Genetic Information, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032 (Japan)

    2015-03-27

    Heterogeneous nuclear ribonucleoprotein K (hnRNP K) is a multi-functional protein involved in transcription, mRNA splicing, mRNA stabilization and translation. Although hnRNP K has been suggested to play a role in the development of many cancers, its molecular function in colorectal cancer has remained elusive. Here we show that hnRNP K plays an important role in the mitotic process in HCT116 colon cancer cells. Furthermore, we demonstrate that hnRNP K directly transactivates the NUF2 gene, the product of which is a component of the NDC80 kinetochore complex and which is known to be critical for a stable spindle microtubule-kinetochore attachment. In addition, knockdown of both hnRNP K and NUF2 caused failure in metaphase chromosome alignment and drastic decrease in the growth of colon cancer cells. These results suggest that the hnRNP K-NUF2 axis is important for the mitotic process and proliferation of colon cancer cells and that this axis could be a target for the therapy of colon cancer. - Highlights: • hnRNP K is required for the tumorigenicity of colon cancer cells. • hnRNP K binds to the promoter region of NUF2 and activates its transcription. • NUF2 expression is correlated with hnRNP K expression in colorectal cancer tissue. • hnRNP K and NUF2 are required for metaphase chromosome alignment. • The hnRNP K-NUF2 axis is important for the proliferation of colon cancer cells.

  8. 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.

  9. Ultraviolet microbeam irradiations of epithelial and spermatocyte spindles suggest that forces act on the kinetochore fibre and are not generated by its disassembly.

    Science.gov (United States)

    Spurck, T; Forer, A; Pickett-Heaps, J

    1997-01-01

    Ultraviolet (UV) microbeam irradiations of crane-fly spermatocyte and newt epithelial spindles severed kinetochore fibres (KT-fibres), creating areas of reduced birefringence (ARBs): the remnant KT-fibre consists of two "stubs," a pole-stub attached to the pole and a KT-stub attached to the kinetochore. KT-stubs remained visible but pole-stubs soon became undetectable [Forer et al., 1996]. At metaphase, in both cell types the KT-stub often changed orientation immediately after irradiation and its tip steadily moved poleward. In spermatocytes, the chromosome attached to the KT-stub remained at the equator as the KT-stub elongated. In epithelial cells, the KT-stub sometimes elongated as the associated chromosome remained at the equator; other times the associated chromosome moved poleward together with the KT-stub, albeit only a short distance toward the pole. When an ARB was generated at anaphase, chromosome(s) with a KT-stub often continued to move poleward. In spermatocytes, this movement was accompanied by steady elongation of the KT-stub. In epithelial cells, chromosomes accelerated polewards after irradiation until the KT-stubs reached the pole, after which chromosome movement returned to normal speeds. In some epithelial cells fine birefringent fibres by chance were present along one edge of ARBs; these remnant fibres buckled and broke as the KT-stub and chromosome moved polewards. Similarly, KT-stubs that moved into pole stubs (or astral fibres) caused the pole stubs (or astral fibres) to bend sharply from the point of impact. Our results contradict models of chromosome movement that postulate that force is generated by the kinetochore disassembling the KT-fibre. Instead, these results suggest that poleward directed forces act on the KT-fibre and the KT-stub and suggest that continuity of microtubules between kinetochore and pole is not obligatory for achieving anaphase motion to the pole.

  10. Progerin impairs chromosome maintenance by depleting CENP-F from metaphase kinetochores in Hutchinson-Gilford progeria fibroblasts.

    Science.gov (United States)

    Eisch, Veronika; Lu, Xiang; Gabriel, Diana; Djabali, Karima

    2016-04-26

    Hutchinson-Gilford progeria syndrome (HGPS, OMIM 176670) is a rare premature aging disorder that leads to death at an average age of 14.7 years due to myocardial infarction or stroke. The most common mutation in HGPS is at position G608G (GGC>GGT) within exon 11 of the LMNA gene. This mutation results in the deletion of 50 amino acids at the carboxyl-terminal tail of prelamin A, producing a truncated farnesylated protein called progerin. Lamins play important roles in the organization and structure of the nucleus. The nuclear build-up of progerin causes severe morphological and functional changes in interphase HGPS cells. In this study, we investigated whether progerin elicits spatiotemporal deviations in mitotic processes in HGPS fibroblasts. We analyzed the nuclear distribution of endogenous progerin during mitosis in relation to components of the nuclear lamina, nuclear envelope (NE) and nuclear pores. We found that progerin caused defects in chromosome segregation as early as metaphase, delayed NE reformation and trapped lamina components and inner NE proteins in the endoplasmic reticulum at the end of mitosis. Progerin displaced the centromere protein F (CENP-F) from metaphase chromosome kinetochores, which caused increased chromatin lagging, binucleated cells and genomic instability. This accumulation of progerin-dependent defects with each round of mitosis predisposes cells to premature senescence.

  11. Distribution of lifetimes of kinetochore-microtubule attachments:interplay of energy landscape, molecular motors and microtubule (de-)polymerization

    CERN Document Server

    Sharma, Ajeet K; Chowdhury, Debashish

    2013-01-01

    Before a cell divides into two daughter cells, the chromosomes are replicated resulting in two sister chromosomes embracing each other. Each sister chromosome is bound to a separate proteinous structure, called kinetochore (kt), that captures the tip of a filamentous protein, called microtubule (MT). Two oppositely oriented MTs pull the two kts attached to two sister chromosomes thereby pulling the two sisters away from each other. Here we theoretically study an even simpler system, namely an isolated kt coupled to a single MT; this system mimics an {\\it in-vitro} experiment where a single kt-MT attachment is reconstituted using purified extracts from budding yeast. Our models not only account for the experimentally observed "catch-bond-like" behavior of the kt-MT coupling, but also make new predictions on the probability distribution of the lifetimes of the attachments. In principle, our new predictions can be tested by analyzing the data collected in the {\\it in-vitro} experiments provided the experiment is...

  12. The mesh is a network of microtubule connectors that stabilizes individual kinetochore fibers of the mitotic spindle.

    Science.gov (United States)

    Nixon, Faye M; Gutiérrez-Caballero, Cristina; Hood, Fiona E; Booth, Daniel G; Prior, Ian A; Royle, Stephen J

    2015-06-19

    Kinetochore fibers (K-fibers) of the mitotic spindle are force-generating units that power chromosome movement during mitosis. K-fibers are composed of many microtubules that are held together throughout their length. Here, we show, using 3D electron microscopy, that K-fiber microtubules (MTs) are connected by a network of MT connectors. We term this network 'the mesh'. The K-fiber mesh is made of linked multipolar connectors. Each connector has up to four struts, so that a single connector can link up to four MTs. Molecular manipulation of the mesh by overexpression of TACC3 causes disorganization of the K-fiber MTs. Optimal stabilization of K-fibers by the mesh is required for normal progression through mitosis. We propose that the mesh stabilizes K-fibers by pulling MTs together and thereby maintaining the integrity of the fiber. Our work thus identifies the K-fiber meshwork of linked multipolar connectors as a key integrator and determinant of K-fiber structure and function.

  13. Condensin HEAT subunits required for DNA repair, kinetochore/centromere function and ploidy maintenance in fission yeast.

    Directory of Open Access Journals (Sweden)

    Xingya Xu

    Full Text Available Condensin, a central player in eukaryotic chromosomal dynamics, contains five evolutionarily-conserved subunits. Two SMC (structural maintenance of chromosomes subunits contain ATPase, hinge, and coiled-coil domains. One non-SMC subunit is similar to bacterial kleisin, and two other non-SMC subunits contain HEAT (similar to armadillo repeats. Here we report isolation and characterization of 21 fission yeast (Schizosaccharomyces pombe mutants for three non-SMC subunits, created using error-prone mutagenesis that resulted in single-amino acid substitutions. Beside condensation, segregation, and DNA repair defects, similar to those observed in previously isolated SMC and cnd2 mutants, novel phenotypes were observed for mutants of HEAT-repeats containing Cnd1 and Cnd3 subunits. cnd3-L269P is hypersensitive to the microtubule poison, thiabendazole, revealing defects in kinetochore/centromere and spindle assembly checkpoints. Three cnd1 and three cnd3 mutants increased cell size and doubled DNA content, thereby eliminating the haploid state. Five of these mutations reside in helix B of HEAT repeats. Two non-SMC condensin subunits, Cnd1 and Cnd3, are thus implicated in ploidy maintenance.

  14. Spindle assembly checkpoint and its regulators in meiosis.

    Science.gov (United States)

    Sun, Shao-Chen; Kim, Nam-Hyung

    2012-01-01

    BACKGROUND Meiosis is a unique form of cell division in which cells divide twice but DNA is duplicated only once. Errors in chromosome segregation during meiosis will result in aneuploidy, followed by loss of the conceptus during pregnancy or birth defects. During mitosis, cells utilize a mechanism called the spindle assembly checkpoint (SAC) to ensure faithful chromosome segregation. A similar mechanism has been uncovered for meiosis in the last decade, especially in the past several years. METHODS For this review, we included data and relevant information obtained through a PubMed database search for all articles published in English from 1991 through 2011 which included the term 'meiosis', 'spindle assembly checkpoint', or 'SAC'. RESULTS There are 91 studies included. Evidence for the existence of SAC functions in meiosis is provided by studies on the SAC proteins mitotic-arrest deficient-1 (Mad1), Mad2, budding uninhibited by benzimidazole-1 (Bub1), Bub3, BubR1 and Mps1; microtubule-kinetochore attachment regulators Ndc80 complex, chromosomal passenger complex, mitotic centromere-associated kinesin (MCAK), kinetochore null 1 (KNL1) and Mis12 complex and spindle stability regulators. CONCLUSIONS SAC and its regulators exist and function in meiosis, and their malfunctions may cause germ cell aneuploidy. However, species and sexual differences exist. Moreover, interaction of SAC components with other regulators is still poorly understood, which needs further study.

  15. The chromosomal passenger complex and the spindle assembly checkpoint: kinetochore-microtubule error correction and beyond

    OpenAIRE

    Maia André F; Vader Gerben; Lens Susanne MA

    2008-01-01

    Abstract During mitosis, correct bipolar chromosome attachment to the mitotic spindle is an essential prerequisite for the equal segregation of chromosomes. The spindle assembly checkpoint can prevent chromosome segregation as long as not all chromosome pairs have obtained bipolar attachment to the spindle. The chromosomal passenger complex plays a crucial role during chromosome alignment by correcting faulty chromosome-spindle interactions (e.g. attachments that do not generate tension). In ...

  16. Gamma-tubulin is required for bipolar spindle assembly and for proper kinetochore microtubule attachments during prometaphase I in Drosophila oocytes.

    Directory of Open Access Journals (Sweden)

    Stacie E Hughes

    2011-08-01

    Full Text Available In many animal species the meiosis I spindle in oocytes is anastral and lacks centrosomes. Previous studies of Drosophila oocytes failed to detect the native form of the germline-specific γ-tubulin (γTub37C in meiosis I spindles, and genetic studies have yielded conflicting data regarding the role of γTub37C in the formation of bipolar spindles at meiosis I. Our examination of living and fixed oocytes carrying either a null allele or strong missense mutation in the γtub37C gene demonstrates a role for γTub37C in the positioning of the oocyte nucleus during late prophase, as well as in the formation and maintenance of bipolar spindles in Drosophila oocytes. Prometaphase I spindles in γtub37C mutant oocytes showed wide, non-tapered spindle poles and disrupted positioning. Additionally, chromosomes failed to align properly on the spindle and showed morphological defects. The kinetochores failed to properly co-orient and often lacked proper attachments to the microtubule bundles, suggesting that γTub37C is required to stabilize kinetochore microtubule attachments in anastral spindles. Although spindle bipolarity was sometimes achieved by metaphase I in both γtub37C mutants, the resulting chromosome masses displayed highly disrupted chromosome alignment. Therefore, our data conclusively demonstrate a role for γTub37C in both the formation of the anastral meiosis I spindle and in the proper attachment of kinetochore microtubules. Finally, multispectral imaging demonstrates the presences of native γTub37C along the length of wild-type meiosis I spindles.

  17. Yeast Interacting Proteins Database: YDR034C, YGR113W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available es kinetochores to the force produced by MT depolymerization thereby aiding in ch... complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization thereby aidin

  18. Yeast Interacting Proteins Database: YNL189W, YDR201W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available plex), couples kinetochores to the force produced by MT depolymerization thereby aiding in chromosome segreg...), couples kinetochores to the force produced by MT depolymerization thereby aiding in chromosome segregatio

  19. Yeast Interacting Proteins Database: YLR423C, YKR083C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available d by MT depolymerization thereby aiding in chromosome segregation; is transferred to the kinetochore prior t...lex), couples kinetochores to the force produced by MT depolymerization thereby aiding in chromosome segrega

  20. Multipolar spindle pole coalescence is a major source of kinetochore mis-attachment and chromosome mis-segregation in cancer cells.

    Directory of Open Access Journals (Sweden)

    William T Silkworth

    Full Text Available Many cancer cells display a CIN (Chromosome Instability phenotype, by which they exhibit high rates of chromosome loss or gain at each cell cycle. Over the years, a number of different mechanisms, including mitotic spindle multipolarity, cytokinesis failure, and merotelic kinetochore orientation, have been proposed as causes of CIN. However, a comprehensive theory of how CIN is perpetuated is still lacking. We used CIN colorectal cancer cells as a model system to investigate the possible cellular mechanism(s underlying CIN. We found that CIN cells frequently assembled multipolar spindles in early mitosis. However, multipolar anaphase cells were very rare, and live-cell experiments showed that almost all CIN cells divided in a bipolar fashion. Moreover, fixed-cell analysis showed high frequencies of merotelically attached lagging chromosomes in bipolar anaphase CIN cells, and higher frequencies of merotelic attachments in multipolar vs. bipolar prometaphases. Finally, we found that multipolar CIN prometaphases typically possessed gamma-tubulin at all spindle poles, and that a significant fraction of bipolar metaphase/early anaphase CIN cells possessed more than one centrosome at a single spindle pole. Taken together, our data suggest a model by which merotelic kinetochore attachments can easily be established in multipolar prometaphases. Most of these multipolar prometaphase cells would then bi-polarize before anaphase onset, and the residual merotelic attachments would produce chromosome mis-segregation due to anaphase lagging chromosomes. We propose this spindle pole coalescence mechanism as a major contributor to chromosome instability in cancer cells.

  1. Targeted Knockdown of the Kinetochore Protein D40/Knl-1 Inhibits Human Cancer in a p53 Status-Independent Manner.

    Science.gov (United States)

    Urata, Yuri N; Takeshita, Fumitaka; Tanaka, Hiroki; Ochiya, Takahiro; Takimoto, Masato

    2015-09-08

    The D40 gene encodes a kinetochore protein that plays an essential role in kinetochore formation during mitosis. Short inhibitory RNA against D40, D40 siRNA, has been shown to deplete the D40 protein in the human cancer cell line HeLa, which harbors wild-type p53, and this activity was followed by the significant inhibition of cell growth and induction of apoptotic cell death. The p53-null cancer cell line, PC-3M-luc, is also sensitive to the significant growth inhibition and cell death induced by D40 siRNA. The growth of PC-3M-luc tumors transplanted into nude mice was inhibited by the systemic administration of D40 siRNA and the atelocollagen complex. Furthermore, D40 siRNA significantly inhibited growth and induced apoptotic cell death in a cell line with a gain-of-function (GOF) mutation in p53, MDA-MB231-luc, and also inhibited the growth of tumors transplanted into mice when administered as a D40 siRNA/atelocollagen complex. These results indicated that D40 siRNA induced apoptotic cell death in human cancer cell lines, and inhibited their growth in vitro and in vivo regardless of p53 status. Therefore, D40 siRNA is a potential candidate anti-cancer reagent.

  2. A hemicentric inversion in the maize line knobless Tama flint created two sites of centromeric elements and moved the kinetochore-forming region.

    Science.gov (United States)

    Lamb, Jonathan C; Meyer, Julie M; Birchler, James A

    2007-06-01

    A maize line, knobless Tama flint (KTF), was found to contain a version of chromosome 8 with two spatially distinct regions of centromeric elements, one at the original genetic position and the other at a novel location on the long arm. The new site of centromeric elements functions as the kinetochore-forming region resulting in a change of arm length ratio. Examination of fluorescence in situ hybridization markers on chromosome 8 revealed an inversion between the two centromere sites relative to standard maize lines, indicating that this chromosome 8 resulted from a hemicentric inversion with one breakpoint approximately 20 centi-McClintocks (cMc) on the long arm (20% of the total arm length from the centromere) and the other in the original cluster of centromere repeats. This inversion moved the kinetochore-forming region but left the remainder of the centromere repeats. In a hybrid between a standard line (Mo17) and KTF, both chromosome 8 homologues were completely synapsed at pachytene despite the inversion. Although the homologous centromeres were not paired, they were always correctly oriented at anaphase and migrated to opposite poles. Additionally, recombination on 8L was severely repressed in the hybrid.

  3. Yeast Interacting Proteins Database: YER081W, YPL233W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available oins kinetochore subunits contacting DNA to those contacting microtubules; requir...tacting DNA to those contacting microtubules; required for accurate chromosome segr...t of the MIND kinetochore complex (Mtw1p Including Nnf1p-Nsl1p-Dsn1p) which joins kinetochore subunits con

  4. INTERACT

    DEFF Research Database (Denmark)

    Jochum, Elizabeth; Borggreen, Gunhild; Murphey, TD

    This paper considers the impact of visual art and performance on robotics and human-computer interaction and outlines a research project that combines puppetry and live performance with robotics. Kinesics—communication through movement—is the foundation of many theatre and performance traditions...... interaction between a human operator and an artificial actor or agent. We can apply insights from puppetry to develop culturally-aware robots. Here we describe the development of a robotic marionette theatre wherein robotic controllers assume the role of human puppeteers. The system has been built, tested...

  5. Unprotected Drosophila melanogaster telomeres activate the spindle assembly checkpoint.

    Science.gov (United States)

    Musarò, Mariarosaria; Ciapponi, Laura; Fasulo, Barbara; Gatti, Maurizio; Cenci, Giovanni

    2008-03-01

    In both yeast and mammals, uncapped telomeres activate the DNA damage response (DDR) and undergo end-to-end fusion. Previous work has shown that the Drosophila HOAP protein, encoded by the caravaggio (cav) gene, is required to prevent telomeric fusions. Here we show that HOAP-depleted telomeres activate both the DDR and the spindle assembly checkpoint (SAC). The cell cycle arrest elicited by the DDR was alleviated by mutations in mei-41 (encoding ATR), mus304 (ATRIP), grp (Chk1) and rad50 but not by mutations in tefu (ATM). The SAC was partially overridden by mutations in zw10 (also known as mit(1)15) and bubR1, and also by mutations in mei-41, mus304, rad50, grp and tefu. As expected from SAC activation, the SAC proteins Zw10, Zwilch, BubR1 and Cenp-meta (Cenp-E) accumulated at the kinetochores of cav mutant cells. Notably, BubR1 also accumulated at cav mutant telomeres in a mei-41-, mus304-, rad50-, grp- and tefu-dependent manner. Our results collectively suggest that recruitment of BubR1 by dysfunctional telomeres inhibits Cdc20-APC function, preventing the metaphase-to-anaphase transition.

  6. Interactions

    DEFF Research Database (Denmark)

    The main theme of this anthology is the unique interaction between mathematics, physics and philosophy during the beginning of the 20th century. Seminal theories of modern physics and new fundamental mathematical structures were discovered or formed in this period. Significant physicists such as ...... also key figures in the philosophical discussions of nature and science - from philosophical tendencies like logical empiricism via critical rationalism to various neo-Kantian trends....

  7. Structural and functional insights into the role of the N-terminal Mps1 TPR domain in the SAC (spindle assembly checkpoint).

    Science.gov (United States)

    Thebault, Philippe; Chirgadze, Dimitri Y; Dou, Zhen; Blundell, Tom L; Elowe, Sabine; Bolanos-Garcia, Victor M

    2012-12-15

    The SAC (spindle assembly checkpoint) is a surveillance system that ensures the timely and accurate transmission of the genetic material to offspring. The process implies kinetochore targeting of the mitotic kinases Bub1 (budding uninhibited by benzamidine 1), BubR1 (Bub1 related) and Mps1 (monopolar spindle 1), which is mediated by the N-terminus of each kinase. In the present study we report the 1.8 Å (1 Å=0.1 nm) crystal structure of the TPR (tetratricopeptide repeat) domain in the N-terminal region of human Mps1. The structure reveals an overall high similarity to the TPR motif of the mitotic checkpoint kinases Bub1 and BubR1, and a number of unique features that include the absence of the binding site for the kinetochore structural component KNL1 (kinetochore-null 1; blinkin), and determinants of dimerization. Moreover, we show that a stretch of amino acids at the very N-terminus of Mps1 is required for dimer formation, and that interfering with dimerization results in mislocalization and misregulation of kinase activity. The results of the present study provide an important insight into the molecular details of the mitotic functions of Mps1 including features that dictate substrate selectivity and kinetochore docking.

  8. Yeast Interacting Proteins Database: YNL189W, YDR318W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available ponent of the COMA complex (Ctf19p, Okp1p, Mcm21p, Ame1p) that bridges kinetochore subunits that are in contact...t of the COMA complex (Ctf19p, Okp1p, Mcm21p, Ame1p) that bridges kinetochore subunits that are in contact w

  9. Yeast Interacting Proteins Database: YKR037C, YLR423C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available etochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; also locali... subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization thereby

  10. Yeast Interacting Proteins Database: YGR113W, YIL144W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; Ipl1p target...kinetochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; Ipl1p ta

  11. Yeast Interacting Proteins Database: YGL061C, YER016W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; is transferr... complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization thereby aidin

  12. Yeast Interacting Proteins Database: YGL061C, YDR016C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; is transferr...hores to the force produced by MT depolymerization thereby aiding in chromosome segregation; is transferred ...roduced by MT depolymerization thereby aiding in chromosome segregation; is transferred to the kinetochore p... Essential subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization thereby

  13. Yeast Interacting Proteins Database: YKR083C, YDR201W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; is transferr...chores to the force produced by MT depolymerization thereby aiding in chromosome segregation; also localized...produced by MT depolymerization thereby aiding in chromosome segregation; is transferred to the kinetochore ...on Essential subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization thereb

  14. Spindle assembly checkpoint signalling is uncoupled from chromosomal position in mouse oocytes.

    Science.gov (United States)

    Gui, Liming; Homer, Hayden

    2012-06-01

    The spindle assembly checkpoint (SAC) averts aneuploidy by coordinating proper bipolar chromosomal attachment with anaphase-promoting complex/cyclosome (APC/C)-mediated securin and cyclin B1 destruction required for anaphase onset. The generation of a Mad2-based signal at kinetochores is central to current models of SAC-based APC/C inhibition. During mitosis, kinetochores of polar-displaced chromosomes, which are at greatest risk of mis-segregating, recruit the highest levels of Mad2, thereby ensuring that SAC activation is proportionate to aneuploidy risk. Paradoxically, although an SAC operates in mammalian oocytes, meiosis I (MI) is notoriously error prone and polar-displaced chromosomes do not prevent anaphase onset. Here we find that Mad2 is not preferentially recruited to the kinetochores of polar chromosomes of wild-type mouse oocytes, in which polar chromosomes are rare, or of oocytes depleted of the kinesin-7 motor CENP-E, in which polar chromosomes are more abundant. Furthermore, in CENP-E-depleted oocytes, although polar chromosomal displacement intensified during MI and the capacity to form stable end-on attachments was severely compromised, all kinetochores nevertheless became devoid of Mad2. Thus, it is possible that the ability of the SAC to robustly discriminate chromosomal position might be compromised by the propensity of oocyte kinetochores to become saturated with unproductive attachments, thereby predisposing to aneuploidy. Our data also reveal novel functions for CENP-E in oocytes: first, CENP-E stabilises BubR1, thereby impacting MI progression; and second, CENP-E mediates bi-orientation by promoting kinetochore reorientation and preventing chromosomal drift towards the poles.

  15. An Arabidopsis tissue-specific RNAi method for studying genes essential to mitosis.

    Directory of Open Access Journals (Sweden)

    Brunilís Burgos-Rivera

    Full Text Available A large fraction of the genes in plants can be considered essential in the sense that when absent the plant fails to develop past the first few cell divisions. The fact that angiosperms pass through a haploid gametophyte stage can make it challenging to propagate such mutants even in the heterozygous condition. Here we describe a tissue-specific RNAi method that allows us to visualize cell division phenotypes in petals, which are large dispensable organs. Portions of the APETALA (AP3 and PISTILLATA (PI promoters confer early petal-specific expression. We show that when either promoter is used to drive the expression of a beta-glucuronidase (GUS RNAi transgene in plants uniformly expressing GUS, GUS expression is knocked down specifically in petals. We further tested the system by targeting the essential kinetochore protein CENPC and two different components of the Spindle Assembly Checkpoint (MAD2 and BUBR1. Plant lines expressing petal-specific RNAi hairpins targeting these genes exhibited an array of petal phenotypes. Cytological analyses of the affected flower buds confirmed that CENPC knockdown causes cell cycle arrest but provided no evidence that either MAD2 or BUBR1 are required for mitosis (although both genes are required for petal growth by this assay. A key benefit of the petal-specific RNAi method is that the phenotypes are not expressed in the lineages leading to germ cells, and the phenotypes are faithfully transmitted for at least four generations despite their pronounced effects on growth.

  16. 极低频磁场联合或不联合X射线对CHO细胞动粒阳性和阴性微核生成的影响%Effects of ELF magnetic fields exposure with or without X-rays on induction of kinetochore positive and negative micronuclei in CHO cells

    Institute of Scientific and Technical Information of China (English)

    DING Guirong; GUO Guozhen

    2005-01-01

    Extremely low frequency magnetic field (ELFMF) produced by power lines and household electric appliances has been associated with increased incidence of cancers, as was suggested by several epidemiological studies[1]. To test the genotoxic effects of ELFMF, the induction of micronuclei by exposure to ELFMF and/or X-rays was investigated by cytokinesis-block method in cultured Chinese Hamster Ovary (CHO) cells. Approximately 4×105 cells were plated in 10cm dishes, following exposure to an ELF magnetic field (60Hz, 5 mT) for 24h. The cells were irradiated to 1 Gy by X-rays. After the irradiation, cytochalasin B was added to the medium at a final concentration of 3 μg / mL. The cells were then exposed to an ELF magnetic field or placed in a normal incubator for 18 h, which is 1.5 times the length of their cell cycle. The micronuclei derived from acentric fragments or from whole chromosomes were evaluated with the help of immunofluorescent staining using antikinetochore antibodies from the serum of scleroderma (CREST syndrome) patients[2,3].Statistically, no significant difference in the frequency of binucleated cells carrying micronuclei was observed between CHO cells cultured in the normal incubator and those placed in the exposure system for 24h. Following X-ray irradiation, the number of binucleated cells carrying micronuclei increased significantly (p< 0.01). Exposure to an ELF magnetic field for 24 h before the X-ray irradiation or for 18 h after X-ray-irradiation did not affect the number of X-ray-induced micronuclei. Among the micronuclei induced by X-ray-irradiation, only a small number were kinetochore-positive (approximately 4 %). The number of kinetochore-positive micronuclei was significantly increased in the cells treated with X-ray irradiation followed by ELFMF exposure or M+X+M treated cells (exposure to ELF magnetic field before and after X-ray irradiation), but not in the cells treated with ELFMF exposure before X-ray irradiation compared with

  17. Yeast Interacting Proteins Database: YKR037C, YGL061C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available etochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; also locali...ochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; is transferre... produced by MT depolymerization thereby aiding in chromosome segregation; also localized to nuclear side of...ion Essential subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization there...by aiding in chromosome segregation; is transferred to the kinetochore prior to mit

  18. Yeast Interacting Proteins Database: YGR113W, YDR016C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; Ipl1p target...etochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; is transfer...e produced by MT depolymerization thereby aiding in chromosome segregation; Ipl1p target for regulating kine... by MT depolymerization thereby aiding in chromosome segregation; is transferred to the kinetochore prior to...ription Essential subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced

  19. Yeast Interacting Proteins Database: YKR037C, YDR016C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available etochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; also locali...ochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; is transferre... produced by MT depolymerization thereby aiding in chromosome segregation; also localized to nuclear side of...ion Essential subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization there...by aiding in chromosome segregation; is transferred to the kinetochore prior to mit

  20. Yeast Interacting Proteins Database: YGR113W, YGL079W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; Ipl1p target...ntial subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization thereby

  1. Yeast Interacting Proteins Database: YGR113W, YLR423C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; Ipl1p target...al subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced by MT depolymerization thereby

  2. Dendrite Development Regulated by the Schizophrenia-Associated Gene FEZ1 Involves the Ubiquitin Proteasome System

    Directory of Open Access Journals (Sweden)

    Yasuhito Watanabe

    2014-04-01

    Full Text Available Downregulation of the schizophrenia-associated gene DISC1 and its interacting protein FEZ1 positively regulates dendrite growth in young neurons. However, little is known about the mechanism that controls these molecules during neuronal development. Here, we identify several components of the ubiquitin proteasome system and the cell-cycle machinery that act upstream of FEZ1. We demonstrate that the ubiquitin ligase cell division cycle 20/anaphase-promoting complex (Cdc20/APC controls dendrite growth by regulating the degradation of FEZ1. Furthermore, dendrite growth is modulated by BubR1, whose known function so far has been restricted to control Cdc20/APC activity during the cell cycle. The modulatory function of BubR1 is dependent on its acetylation status. We show that BubR1 is deacetylated by Hdac11, thereby disinhibiting the Cdc20/APC complex. Because dendrite growth is affected both in hippocampal dentate granule cells and olfactory bulb neurons upon modifying expression of these genes, we conclude that the proposed mechanism governs neuronal development in a general fashion.

  3. Collocated Interaction

    DEFF Research Database (Denmark)

    E. Fischer, Joel; Porcheron, Martin; Lucero, Andrés;

    2016-01-01

    , and wearable technologies, spaces and spatial interaction, and those interested in the social aspects of interaction, such as conversation analysis and ethnomethodology. These communities have matured considerably, and produced significant exemplars of systems, methods, and studies concerned with collocated...

  4. ERK3 is required for metaphase-anaphase transition in mouse oocyte meiosis.

    Directory of Open Access Journals (Sweden)

    Sen Li

    Full Text Available ERK3 (extracellular signal-regulated kinase 3 is an atypical member of the mitogen-activated protein (MAP kinase family of serine/threonine kinases. Little is known about its function in mitosis, and even less about its roles in mammalian oocyte meiosis. In the present study, we examined the localization, expression and functions of ERK3 during mouse oocyte meiotic maturation. Immunofluorescent analysis showed that ERK3 localized to the spindles from the pre-MI stage to the MII stage. ERK3 co-localized with α-tubulin on the spindle fibers and asters in oocytes after taxol treatment. Deletion of ERK3 by microinjection of ERK3 morpholino (ERK3 MO resulted in oocyte arrest at the MI stage with severely impaired spindles and misaligned chromosomes. Most importantly, the spindle assembly checkpoint protein BubR1 could be detected on kinetochores even in oocytes cultured for 10 h. Low temperature treatment experiments indicated that ERK3 deletion disrupted kinetochore-microtubule (K-MT attachments. Chromosome spreading experiments showed that knock-down of ERK3 prevented the segregation of homologous chromosomes. Our data suggest that ERK3 is crucial for spindle stability and required for the metaphase-anaphase transition in mouse oocyte maturation.

  5. Cenp-meta is required for sustained spindle checkpoint

    Directory of Open Access Journals (Sweden)

    Thomas Rubin

    2014-05-01

    Full Text Available Cenp-E is a kinesin-like motor protein required for efficient end-on attachment of kinetochores to the spindle microtubules. Cenp-E immunodepletion in Xenopus mitotic extracts results in the loss of mitotic arrest and massive chromosome missegregation, whereas its depletion in mammalian cells leads to chromosome segregation defects despite the presence of a functional spindle assembly checkpoint (SAC. Cenp-meta has previously been reported to be the Drosophila homolog of vertebrate Cenp-E. In this study, we show that cenp-metaΔ mutant neuroblasts arrest in mitosis when treated with colchicine. cenp-metaΔ mutant cells display a mitotic delay. Yet, despite the persistence of the two checkpoint proteins Mad2 and BubR1 on unattached kinetochores, these cells eventually enter anaphase and give rise to highly aneuploid daughter cells. Indeed, we find that cenp-metaΔ mutant cells display a slow but continuous degradation of cyclin B, which eventually triggers the mitotic exit observed. Thus, our data provide evidence for a role of Cenp-meta in sustaining the SAC response.

  6. Yeast Interacting Proteins Database: YGR113W, YGL061C [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; Ipl1p target...etochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; is transfer...rce produced by MT depolymerization thereby aiding in chromosome segregation; Ipl1p target for regulating ki...ed by MT depolymerization thereby aiding in chromosome segregation; is transferred to the kinetochore prior

  7. Yeast Interacting Proteins Database: YKR037C, YDR201W [Yeast Interacting Proteins Database

    Lifescience Database Archive (English)

    Full Text Available etochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; also locali...tochores to the force produced by MT depolymerization thereby aiding in chromosome segregation; also localiz...rce produced by MT depolymerization thereby aiding in chromosome segregation; also localized to nuclear side... by MT depolymerization thereby aiding in chromosome segregation; also localized to nuclear side of spindle ...ription Essential subunit of the Dam1 complex (aka DASH complex), couples kinetochores to the force produced

  8. Floor interaction

    DEFF Research Database (Denmark)

    Petersen, Marianne Graves; Krogh, Peter; Ludvigsen, Martin;

    2005-01-01

    Within architecture, there is a long tradition of careful design of floors. The design has been concerned with both decorating floors and designing floors to carry information. Ubiquitous computing technology offers new opportunities for designing interactive floors. This paper presents three...... different interactive floor concepts. Through an urban perspective it draws upon the experiences of floors in architecture, and provides a set of design issues for designing interactive floors....

  9. Explicit Interaction

    DEFF Research Database (Denmark)

    Löwgren, Jonas; Eriksen, Mette Agger; Linde, Per

    2006-01-01

    as an interpretation of palpability, comprising usability as well as patient empowerment and socially performative issues. We present a prototype environment for video recording during physiotherapeutical consultation which illustrates our current thoughts on explicit interaction and serves as material for further......We report an ongoing study of palpable computing to support surgical rehabilitation, in the general field of interaction design for ubiquitous computing. Through explorative design, fieldwork and participatory design techniques, we explore the design principle of explicit interaction...

  10. Playful Interaction

    DEFF Research Database (Denmark)

    2003-01-01

    The video Playful Interaction describes a future architectural office, and envisions ideas and concepts for playful interactions between people, materials and appliances in a pervasive and augmented working environment. The video both describes existing developments, technologies and designs...... as well as ideas not yet implemented such as playful modes of interaction with an augmented ball. Playful Interaction has been used as a hybrid of a vision video and a video prototype (1). Externally the video has been used to visualising our new ideas, and internally the video has also worked to inspire...

  11. Interactive benchmarking

    DEFF Research Database (Denmark)

    Lawson, Lartey; Nielsen, Kurt

    2005-01-01

    We discuss individual learning by interactive benchmarking using stochastic frontier models. The interactions allow the user to tailor the performance evaluation to preferences and explore alternative improvement strategies by selecting and searching the different frontiers using directional...... in the suggested benchmarking tool. The study investigates how different characteristics on dairy farms influences the technical efficiency....

  12. Aesthetic interaction

    DEFF Research Database (Denmark)

    Petersen, Marianne Graves; Iversen, Ole Sejer; Krogh, Peter;

    2004-01-01

    There is a growing interest in considering aesthetic aspects in the design of interactive systems. A set of approaches are emerging each representing different applications of the terminology as well as different inherent assumptions on the role of the user, designer and interaction ideals....... In this paper, we use the concept of Pragmatist Aesthetics to provide a framework for distinguishing between different approaches to aesthetics. Moreover, we use our own design cases to illustrate how pragmatist aesthetics is a promising path to follow in the context of designing interactive systems......, as it promotes aesthetics of use, rather than aesthetics of appearance. We coin this approach in the perspective of aesthetic interaction. Finally we make the point that aesthetics is not re-defining everything known about interactive systems. We provide a framework placing this perspective among other...

  13. Programming Interactivity

    CERN Document Server

    Noble, Joshua

    2012-01-01

    Ready to create rich interactive experiences with your artwork, designs, or prototypes? This is the ideal place to start. With this hands-on guide, you'll explore several themes in interactive art and design-including 3D graphics, sound, physical interaction, computer vision, and geolocation-and learn the basic programming and electronics concepts you need to implement them. No previous experience is necessary. You'll get a complete introduction to three free tools created specifically for artists and designers: the Processing programming language, the Arduino microcontroller, and the openFr

  14. Interaction graphs

    DEFF Research Database (Denmark)

    Seiller, Thomas

    2016-01-01

    Interaction graphs were introduced as a general, uniform, construction of dynamic models of linear logic, encompassing all Geometry of Interaction (GoI) constructions introduced so far. This series of work was inspired from Girard's hyperfinite GoI, and develops a quantitative approach that should...... be understood as a dynamic version of weighted relational models. Until now, the interaction graphs framework has been shown to deal with exponentials for the constrained system ELL (Elementary Linear Logic) while keeping its quantitative aspect. Adapting older constructions by Girard, one can clearly define...... "full" exponentials, but at the cost of these quantitative features. We show here that allowing interpretations of proofs to use continuous (yet finite in a measure-theoretic sense) sets of states, as opposed to earlier Interaction Graphs constructions were these sets of states were discrete (and finite...

  15. Neutrino Interactions

    CERN Document Server

    McFarland, Kevin

    2008-01-01

    This manuscript summarizes a series of three lectures on interactions of neutrinos . The lectures begin with a pedagogical foundation and then explore topics of interest to current and future neutrino oscillation and cross-section experiments.

  16. Embarrassing Interactions

    DEFF Research Database (Denmark)

    Deterding, Sebastian; Lucero, Andrés; Holopainen, Jussi;

    2015-01-01

    Wherever the rapid evolution of interactive technologies disrupts standing situational norms, creates new, often unclear situational audiences, or crosses cultural boundaries, embarrassment is likely. This makes embarrassment a fundamental adoption and engagement hurdle, but also a creative design...

  17. Hadronic Interactions

    CERN Document Server

    Yamazaki, Takeshi

    2015-01-01

    Understanding hadronic interactions is crucial for investigating the properties of unstable hadrons, since measuring physical quantities for unstable hadrons including the resonance mass and decay width requires simultaneous calculations of final scattering states. Recent studies of hadronic scatterings and decays are reviewed from this point of view. The nuceon-nucleon and multi-nucleon interactions are very important to understand the formation of nucleus from the first principle of QCD. These interactions have been studied mainly by two methods, due originally to L\\"uscher and to HALQCD. The results obtained from the two methods are compared in three channels, $I=2$ two-pion, H-dibaryon, and two-nucleon channels. So far the results from the two methods for the two-nucleon channels are different even at the level of the presence or absence of bound states. We then discuss possible uncertainties in each method. Recent results on the binding energy for helium nuclei are also reviewed.

  18. Interaction Widget

    DEFF Research Database (Denmark)

    Ingstrup, Mads

    2003-01-01

    This pattern describes the idea of making a user interface of discrete, reusable entities---here called interaction widgets. The idea behind widgets is described using two perspectives, that of the user and that of the developer. It is the forces from these two perspectives that are balanced in t...... in the pattern. The intended audience of the pattern is developers and researchers within the field of human computer interaction.......This pattern describes the idea of making a user interface of discrete, reusable entities---here called interaction widgets. The idea behind widgets is described using two perspectives, that of the user and that of the developer. It is the forces from these two perspectives that are balanced...

  19. Interactive governance

    DEFF Research Database (Denmark)

    Sørensen, Eva; Torfing, Jacob; Peters, B. Guy

    Governance has become one of the most commonly used concepts in contemporary political science. It is, however, often used to mean a variety of different things. This book helps to clarify this conceptual muddle by concentrating on one variety of governance-interactive governance. The authors argue...... that although the state may remain important for many aspects of governing, interactions between state and society represent an important, and perhaps increasingly important, dimension of governance. These interactions may be with social actors such as networks, with market actors or with other governments......, but all these forms represent means of governing involving mixtures of state action with the actions of other entities.This book explores thoroughly this meaning of governance, and links it to broader questions of governance. In the process of explicating this dimension of governance the authors also...

  20. Programming Interactivity

    CERN Document Server

    Noble, Joshua

    2009-01-01

    Make cool stuff. If you're a designer or artist without a lot of programming experience, this book will teach you to work with 2D and 3D graphics, sound, physical interaction, and electronic circuitry to create all sorts of interesting and compelling experiences -- online and off. Programming Interactivity explains programming and electrical engineering basics, and introduces three freely available tools created specifically for artists and designers: Processing, a Java-based programming language and environment for building projects on the desktop, Web, or mobile phonesArduino, a system t

  1. Kinesthetic Interaction

    DEFF Research Database (Denmark)

    Fogtmann, Maiken Hillerup; Fritsch, Jonas; Kortbek, Karen Johanne

    2008-01-01

    Within the Human-Computer Interaction community there is a growing interest in designing for the whole body in interaction design. The attempts aimed at addressing the body have very different outcomes spanning from theoretical arguments for understanding the body in the design process, to more...... to reveal bodily potential in relation to three design themes – kinesthetic development, kinesthetic means and kinesthetic disorder; and seven design parameters – engagement, sociality, movability, explicit motivation, implicit motivation, expressive meaning and kinesthetic empathy. The framework is a tool...

  2. OSBP-related protein 8 (ORP8) interacts with Homo sapiens sperm associated antigen 5 (SPAG5) and mediates oxysterol interference of HepG2 cell cycle.

    Science.gov (United States)

    Zhong, Wenbin; Zhou, You; Li, Jiwei; Mysore, Raghavendra; Luo, Wei; Li, Shiqian; Chang, Mau-Sun; Olkkonen, Vesa M; Yan, Daoguang

    2014-04-01

    We earlier identified OSBP-related protein 8 (ORP8) as an endoplasmic reticulum/nuclear envelope oxysterol-binding protein implicated in cellular lipid homeostasis, migration, and organization of the microtubule cytoskeleton. Here, a yeast two-hybrid screen identified Homo sapiens sperm associated antigen 5 (SPAG5)/Astrin as interaction partner of ORP8. The putative interaction was further confirmed by pull-down and co-immunoprecipitation assays. ORP8 did not colocalize with kinetochore-associated SPAG5 in mitotic HepG2 or HuH7 cells, but overexpressed ORP8 was capable of recruiting SPAG5 onto endoplasmic reticulum membranes in interphase cells. In our experiments, 25-hydroxycholesterol (25OHC) retarded the HepG2 cell cycle, causing accumulation in G2/M phase; ORP8 overexpression resulted in the same phenotype. Importantly, ORP8 knock-down dramatically inhibited the oxysterol effect on HepG2 cell cycle, suggesting a mediating role of ORP8. Furthermore, knock-down of SPAG5 significantly reduced the effects of both ORP8 overexpression and 25OHC on the cell cycle, placing SPAG5 downstream of the two cell-cycle interfering factors. Taken together, the present results suggest that ORP8 may via SPAG5 mediate oxysterol interference of the HepG2 cell cycle.

  3. Audiovisual Interaction

    DEFF Research Database (Denmark)

    Karandreas, Theodoros-Alexandros

    importance of each modality with respect to the overall quality evaluation. The results show that this was not due to specific interactions between stimuli but rather because the auditory modality dominated over the visual modality. Furthermore, for all experiments where less than optimal stimuli...

  4. Interactive Storytelling

    DEFF Research Database (Denmark)

    Schoenau-Fog, Henrik; Reng, Lars

    2015-01-01

    This book constitutes the refereed proceedings of the 8th International Conference on Interactive Digital Storytelling, ICIDS 2015, held in Copenhagen, Denmark, in November/December 2015. The 18 revised full papers and 13 short papers presented together with 9 posters, 9 workshop descriptions, an...

  5. Interactive Astronomy.

    Science.gov (United States)

    Martin, Jean K.

    1997-01-01

    Presents guiding principles for developing interactive lessons for the World Wide Web. Describes "Amazing Space: Education Online from the Hubble Space Telescope", a program where students study spectacular Hubble Space Telescope images of stars and star-forming regions to learn about the life cycle of stars and the creation of atoms. (JRH)

  6. Interacting Electrons

    Science.gov (United States)

    Martin, Richard M.; Reining, Lucia; Ceperley, David M.

    2016-06-01

    Preface; Part I. Interacting Electrons: Beyond the Independent-Particle Picture: 1. The many electron problem: introduction; 2. Signatures of electron correlation; 3. Concepts and models for interacting electrons; Part II. Foundations of Theory for Many-Body Systems: 4. Mean fields and auxiliary systems; 5. Correlation functions; 6. Many-body wavefunctions; 7. Particles and quasi-particles; 8. Functionals in many-particle physics; Part III. Many-Body Green's Function Methods: 9. Many-body perturbation theory: expansion in the interaction; 10. Many-body perturbation theory via functional derivatives; 11. The RPA and the GW approximation for the self-energy; 12. GWA calculations in practice; 13. GWA calculations: illustrative results; 14. RPA and beyond: the Bethe-Salpeter equation; 15. Beyond the GW approximation; 16. Dynamical mean field theory; 17. Beyond the single-site approximation in DMFT; 18. Solvers for embedded systems; 19. Characteristic hamiltonians for solids with d and f states; 20. Examples of calculations for solids with d and f states; 21. Combining Green's functions approaches: an outlook; Part IV. Stochastic Methods: 22. Introduction to stochastic methods; 23. Variational Monte Carlo; 24. Projector quantum Monte Carlo; 25. Path integral Monte Carlo; 26. Concluding remarks; Part V. Appendices: A. Second quantization; B. Pictures; C. Green's functions: general properties; D. Matsubara formulation for Green's functions for T ̸= 0; E. Time-ordering, contours, and non-equilibrium; F. Hedin's equations in a basis; G. Unique solutions in Green's function theory; H. Properties of functionals; I. Auxiliary systems and constrained search; J. Derivation of the Luttinger theorem; K. Gutzwiller and Hubbard approaches; References; Index.

  7. Interactive Governance

    DEFF Research Database (Denmark)

    Bang, Henrik

    2016-01-01

    Governance analysis has exploded in recent years, and it has become nearly impossible to tell what difference the concept and practice of governance makes from those of government and state. In addition governance analysis has been placed more and more in the shadow of the new institutionalisms and...... and growth. However, interactive governance is not a property or effect of institutions; nor does it apply solely to those individuals who seek success above everything else. It is connective more than individualistic or collectivistic in nature; and it manifests a governability capacity which...

  8. Sibling interaction.

    Science.gov (United States)

    Balsam, Rosemary H

    2013-01-01

    Sibling interactions traditionally were conceived psychoanalytically in "vertical" and parentified oedipal terms and overlooked in their own right, for complicated reasons (Colonna and Newman 1983). Important work has been done to right this, from the 1980s and onward, with conferences and writings. Juliet Mitchell's 2000 and, in particular, her 2003 books, for example, have brought "lateral" sibling relations forcefully to the forefront of insights, especially about sex and violence, with the added interdisciplinary impact of illuminating upheaval in global community interactions as well as having implications for clinicians. A clinical example from the analysis of an adult woman with a ten-years-younger sister will show here how we need both concepts to help us understand complex individual psychic life. The newer "lateral" sibling emphasis, including Mitchell's "Law of the Mother" and "seriality," can be used to inform the older "vertical" take, to enrich the full dimensions of intersubjective oedipal and preoedipal reciprocities that have been foundational in shaping that particular analysand's inner landscape. Some technical recommendations for heightening sensitivity to the import of these dynamics will be offered along the way here, by invoking Hans Loewald's useful metaphor of the analytic situation as theater.

  9. Electromagnetic interactions

    CERN Document Server

    Bosanac, Slobodan Danko

    2016-01-01

    This book is devoted to theoretical methods used in the extreme circumstances of very strong electromagnetic fields. The development of high power lasers, ultrafast processes, manipulation of electromagnetic fields and the use of very fast charged particles interacting with other charges requires an adequate theoretical description. Because of the very strong electromagnetic field, traditional theoretical approaches, which have primarily a perturbative character, have to be replaced by descriptions going beyond them. In the book an extension of the semi-classical radiation theory and classical dynamics for particles is performed to analyze single charged atoms and dipoles submitted to electromagnetic pulses. Special attention is given to the important problem of field reaction and controlling dynamics of charges by an electromagnetic field.

  10. Electromagnetic interactions

    Energy Technology Data Exchange (ETDEWEB)

    Bosanac, Slobodan Danko [Ruder Boskovic Institute, Zagreb (Croatia). Physical Chemistry

    2016-07-01

    This book is devoted to theoretical methods used in the extreme circumstances of very strong electromagnetic fields. The development of high power lasers, ultrafast processes, manipulation of electromagnetic fields and the use of very fast charged particles interacting with other charges requires an adequate theoretical description. Because of the very strong electromagnetic field, traditional theoretical approaches, which have primarily a perturbative character, have to be replaced by descriptions going beyond them. In the book an extension of the semi-classical radiation theory and classical dynamics for particles is performed to analyze single charged atoms and dipoles submitted to electromagnetic pulses. Special attention is given to the important problem of field reaction and controlling dynamics of charges by an electromagnetic field.

  11. Designing "Interaction": How Do Interaction Design Students Address Interaction?

    Science.gov (United States)

    Karlgren, Klas; Ramberg, Robert; Artman, Henrik

    2016-01-01

    Interaction design is usually described as being concerned with interactions with and through artifacts but independent of a specific implementation. Design work has been characterized as a conversation between the designer and the situation and this conversation poses a particular challenge for interaction design as interactions can be elusive…

  12. Cloud Interactions

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] Released 1 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth. Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms. This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere. Image information: VIS instrument. Latitude 68.4, Longitude 258.8 East (101.2 West). 38 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara

  13. Unification of Electromagnetic Interactions and Gravitational Interactions

    Institute of Scientific and Technical Information of China (English)

    WUNing

    2002-01-01

    Unified theory of gravitational interactions and electromagnetic interactions is discussed in this paper.Based on gauge principle,electromagnetic interactions and gravitational interactions are formulated in the same manner and are unified in a semi-direct product group of U(1) Abelian gauge group and gravitational gauge group.

  14. Unification of Electromagnetic Interactions and Gravitational Interactions

    Institute of Scientific and Technical Information of China (English)

    WU Ning

    2002-01-01

    Unified theory of gravitational interactions and electromagnetic interactions is discussed in this paper.Based on gauge principle, electromagnetic interactions and gravitational interactions are formulated in the same mannerand are unified in a semi-direct product group of U(1) Abelian gauge group and gravitational gauge group.

  15. OSBP-related protein 8 (ORP8) interacts with Homo sapiens sperm associated antigen 5 (SPAG5) and mediates oxysterol interference of HepG2 cell cycle

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Wenbin [Department of Biotechnology, Jinan University, Guangzhou 510632 (China); Zhou, You [Minerva Foundation Institute for Medical Research, Helsinki (Finland); Li, Jiwei [Department of Biotechnology, Jinan University, Guangzhou 510632 (China); Mysore, Raghavendra [Minerva Foundation Institute for Medical Research, Helsinki (Finland); Luo, Wei; Li, Shiqian [Department of Biotechnology, Jinan University, Guangzhou 510632 (China); Chang, Mau-Sun [Institute of Biochemical Sciences, National Taiwan University, No. 1, Taipei, Taiwan (China); Olkkonen, Vesa M. [Minerva Foundation Institute for Medical Research, Helsinki (Finland); Yan, Daoguang, E-mail: tydg@jnu.edu.cn [Department of Biotechnology, Jinan University, Guangzhou 510632 (China)

    2014-04-01

    We earlier identified OSBP-related protein 8 (ORP8) as an endoplasmic reticulum/nuclear envelope oxysterol-binding protein implicated in cellular lipid homeostasis, migration, and organization of the microtubule cytoskeleton. Here, a yeast two-hybrid screen identified Homo sapiens sperm associated antigen 5 (SPAG5)/Astrin as interaction partner of ORP8. The putative interaction was further confirmed by pull-down and co-immunoprecipitation assays. ORP8 did not colocalize with kinetochore-associated SPAG5 in mitotic HepG2 or HuH7 cells, but overexpressed ORP8 was capable of recruiting SPAG5 onto endoplasmic reticulum membranes in interphase cells. In our experiments, 25-hydroxycholesterol (25OHC) retarded the HepG2 cell cycle, causing accumulation in G2/M phase; ORP8 overexpression resulted in the same phenotype. Importantly, ORP8 knock-down dramatically inhibited the oxysterol effect on HepG2 cell cycle, suggesting a mediating role of ORP8. Furthermore, knock-down of SPAG5 significantly reduced the effects of both ORP8 overexpression and 25OHC on the cell cycle, placing SPAG5 downstream of the two cell-cycle interfering factors. Taken together, the present results suggest that ORP8 may via SPAG5 mediate oxysterol interference of the HepG2 cell cycle. - Highlights: • The oxysterol-binding protein ORP8 was found to interact with the mitotic regulator SPAG5/Astrin. • Treatment of HepG2 cells with 25-hydroxycholesterol caused cell cycle retardation in G2/M. • ORP8 overexpression caused a similar G2/M accumulation, and ORP8 knock-down reversed the 25-hydroxycholesterol effect. • Reduction of cellular of SPAG5/Astrin reversed the cell cycle effects of both 25-hydroxycholesterol and ORP8 overexpression. • Our results suggest that ORP8 mediates via SPAG5/Astrin the oxysterol interference of HepG2 cell cycle.

  16. CXI-benzo-84 reversibly binds to tubulin at colchicine site and induces apoptosis in cancer cells.

    Science.gov (United States)

    Rai, Ankit; Gupta, Tilak Kumar; Kini, Sudarshan; Kunwar, Ambarish; Surolia, Avadhesha; Panda, Dulal

    2013-08-01

    Here, we have discovered CXI-benzo-84 as a potential anticancer agent from a library of benzimidazole derivatives using cell based screening strategy. CXI-benzo-84 inhibited cell cycle progression in metaphase stage of mitosis and accumulated spindle assembly checkpoint proteins Mad2 and BubR1 on kinetochores, which subsequently activated apoptotic cell death in cancer cells. CXI-benzo-84 depolymerized both interphase and mitotic microtubules, perturbed EB1 binding to microtubules and inhibited the assembly and GTPase activity of tubulin in vitro. CXI-benzo-84 bound to tubulin at a single binding site with a dissociation constant of 1.2±0.2μM. Competition experiments and molecular docking suggested that CXI-benzo-84 binds to tubulin at the colchicine-site. Further, computational analysis provided a significant insight on the binding site of CXI-benzo-84 on tubulin. In addition to its potential use in cancer chemotherapy, CXI-benzo-84 may also be useful to screen colchicine-site agents and to understand the colchicine binding site on tubulin.

  17. Drug Interaction API

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Interaction API is a web service for accessing drug-drug interactions. No license is needed to use the Interaction API. Currently, the API uses DrugBank for its...

  18. N-Acetyl-D-Glucosamine Kinase Interacts with Dynein-Lis1-NudE1 Complex and Regulates Cell Division.

    Science.gov (United States)

    Sharif, Syeda Ridita; Islam, Ariful; Moon, Il Soo

    2016-09-01

    N-acetyl-D-glucosamine kinase (GlcNAc kinase or NAGK) primarily catalyzes phosphoryl transfer to GlcNAc during amino sugar metabolism. Recently, it was shown NAGK interacts with dynein light chain roadblock type 1 (DYNLRB1) and upregulates axo-dendritic growth, which is an enzyme activity-independent, non-canonical structural role. The authors examined the distributions of NAGK and NAGK-dynein complexes during the cell cycle in HEK293T cells. NAGK was expressed throughout different stages of cell division and immunocytochemistry (ICC) showed NAGK was localized at nuclear envelope, spindle microtubules (MTs), and kinetochores (KTs). A proximity ligation assay (PLA) for NAGK and DYNLRB1 revealed NAGK-dynein complex on nuclear envelopes in prophase cells and on chromosomes in metaphase cells. NAGK-DYNLRB1 PLA followed by Lis1/NudE1 immunostaining showed NAGK-dynein complexes were colocalized with Lis1 and NudE1 signals, and PLA for NAGK-Lis1 showed similar signal patterns, suggesting a functional link between NAGK and dynein-Lis1 complex. Subsequently, NAGK-dynein complexes were found in KTs and on nuclear membranes where KTs were marked with CENP-B ICC and nuclear membrane with lamin ICC. Furthermore, knockdown of NAGK by small hairpin (sh) RNA was found to delay cell division. These results indicate that the NAGK-dynein interaction with the involvements of Lis1 and NudE1 plays an important role in prophase nuclear envelope breakdown (NEB) and metaphase MT-KT attachment during eukaryotic cell division.

  19. Problem of interactions: electromagnetic particles interaction

    CERN Document Server

    Sannikov-Proskuryakov, S S

    2001-01-01

    The electromagnetic interactions between charged particles are derived on the basis of the particles dynamic theory, proposed in the work of Sannikov. The electromagnetic interactions exist only in the relativistic model of the bihamiltonian system, based on the Heisenberg algebra. Existence of this type of interactions is connected with the U sub e (1)-degeneration of the basic state of the relativistic bihamiltonian system, lying in the basis of the given theory

  20. Dynamic distribution of TTK in HeLa cells: insights from an ultrastructural study

    Institute of Scientific and Technical Information of China (English)

    ZHEN DOU; AKIRA SAWAGECHI; JIE ZHANG; HONG LUO; LAWRENCE BRAKO; XUE BIAO YAO

    2003-01-01

    Entry into mitosis is driven by signaling cascades of mitotic kinases.Our recent studies show that TTK,a kinetochore-associated protein kinase,interacts with CENP-E,a mitotic kinesin located to corona fiber ofkinetochore.Using immunoelectron microscopy,here we show that TTK is present at the nuclear pore adjacent complex of interphase HeLa cells.Upon nuclear envelope fragmentation,TTK targets to the outermostregion of the developing kinetochores ofmonoorient chromosome as well as to spindle poles.After stable attachment,throughout chromosome congression,TTK is a constituent of the corona fibers,extending up to 90 nm away from the kinetochore outer plate.Upon metaphase alignment,TTK departs from the kinetochore and migrates toward the centrosomes.Taken together,this evidence strongly supports a model in which TTK functions in spindle checkpoint signaling cascades at both kinetochore and centrosome.

  1. Interactive pinball business

    DEFF Research Database (Denmark)

    Buur, Jacob; Gudiksen, Sune Klok

    2012-01-01

    Interaction design expands into new fields. Interaction design and business model innovation is a promising meeting of disciplines: Many businesses see the need to rethink their ways of doing business, and, as business models pose highly dynamic and interactive problems, interaction design has much...

  2. PIC: Protein Interactions Calculator.

    Science.gov (United States)

    Tina, K G; Bhadra, R; Srinivasan, N

    2007-07-01

    Interactions within a protein structure and interactions between proteins in an assembly are essential considerations in understanding molecular basis of stability and functions of proteins and their complexes. There are several weak and strong interactions that render stability to a protein structure or an assembly. Protein Interactions Calculator (PIC) is a server which, given the coordinate set of 3D structure of a protein or an assembly, computes various interactions such as disulphide bonds, interactions between hydrophobic residues, ionic interactions, hydrogen bonds, aromatic-aromatic interactions, aromatic-sulphur interactions and cation-pi interactions within a protein or between proteins in a complex. Interactions are calculated on the basis of standard, published criteria. The identified interactions between residues can be visualized using a RasMol and Jmol interface. The advantage with PIC server is the easy availability of inter-residue interaction calculations in a single site. It also determines the accessible surface area and residue-depth, which is the distance of a residue from the surface of the protein. User can also recognize specific kind of interactions, such as apolar-apolar residue interactions or ionic interactions, that are formed between buried or exposed residues or near the surface or deep inside.

  3. Designing for mobile interaction

    DEFF Research Database (Denmark)

    Nazzi, Elena

    2009-01-01

    The theme of this PhD project is designing for mobile interaction with devices and services, for the accessing, making, and sharing of information, taking into account the dynamic physical and social settings that embrace this interaction. To narrow down this theme, the whole project focuses...... on the exploitation of social interaction --- in particular among senior citizens --- to enhance and support mobile interaction....

  4. Interaction for visualization

    CERN Document Server

    Tominski, Christian

    2015-01-01

    Visualization has become a valuable means for data exploration and analysis. Interactive visualization combines expressive graphical representations and effective user interaction. Although interaction is an important component of visualization approaches, much of the visualization literature tends to pay more attention to the graphical representation than to interaction.The goal of this work is to strengthen the interaction side of visualization. Based on a brief review of general aspects of interaction, we develop an interaction-oriented view on visualization. This view comprises five key as

  5. Interactive CFD simulations

    OpenAIRE

    Duque Lombana, Juan Fernando

    2007-01-01

    This project is about the development of an implementable Interactive Computer Fluid Dynamics methodology -- The range of this work begins with an overview of the current status of computational fluid dynamics simulation software and methodologies, continues with an introduction to what interactive and interactivity mean, develops an all original interactive CFD methodology to follow for the solution of fluid scenarios and finally, the description of the implementation of an interactive solve...

  6. Interactive Pinball Business

    DEFF Research Database (Denmark)

    Buur, Jacob; Gudiksen, Sune

    2012-01-01

    Interaction design expands into new fields. Interaction design and business model innovation is a promising meeting of disciplines: Many businesses see the need to rethink their ways of doing business, and, as business models pose highly dynamic and interactive problems, interaction design has much...... to offer. This paper compares ‘tangible business models’ in the form of pinball-like contraptions, designed by interaction design students with those developed by groups of professionals around concrete business issues. We will show how the interactive models encourage business people to play...... with hypotheses and experiment with scenarios as a way of innovating their business models, and why this is so....

  7. Interacting agents in finance

    NARCIS (Netherlands)

    C. Hommes

    2008-01-01

    Interacting agents in finance represent a behavioural, agent-based approach in which financial markets are viewed as complex adaptive systems consisting of many boundedly rational agents interacting through simple heterogeneous investment strategies, constantly adapting their behaviour in response t

  8. Health Data Interactive (HDI)

    Data.gov (United States)

    U.S. Department of Health & Human Services — Health Data Interactive (HDI) presents a broad range of important public health indicators through an interactive web-based application that provides access to...

  9. Sea Turtle Interaction Report

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Sea Turtle Interaction Report is a report sent out in pdf format to authorized individuals that summarizes sea turtle interactions in the longline fishery. The...

  10. Gestalt Interactional Groups

    Science.gov (United States)

    Harman, Robert L.; Franklin, Richard W.

    1975-01-01

    Gestalt therapy in groups is not limited to individual work in the presence of an audience. Describes several ways to involve gestalt groups interactionally. Interactions described focus on learning by doing and discovering, and are noninterpretive. (Author/EJT)

  11. Diachronic Perspective and Interaction

    DEFF Research Database (Denmark)

    Marchetti, Emanuela; Valente, Andrea

    . An ongoing participatory inquiry is being conducted, to explore deeper forms of learning and communication for historical museums. Our hypothesis is that the diachronic perspective on historical processes, defined as social interaction within the environment through time, is a key missing element....... Explorations of more interactive representations of the diachronic perspective, through play and tangible interaction, may foster a dialogue with young visitors. Therefore, a new interactive installation is being designed, intended as a tool to enrich learning, allowing children to experience historical...

  12. Gaze Interactive Building Instructions

    DEFF Research Database (Denmark)

    Hansen, John Paulin; Ahmed, Zaheer; Mardanbeigi, Diako

    We combine eye tracking technology and mobile tablets to support hands-free interaction with digital building instructions. As a proof-of-concept we have developed a small interactive 3D environment where one can interact with digital blocks by gaze, keystroke and head gestures. Blocks may be moved...

  13. Interactivity: A Forgotten Art?

    Science.gov (United States)

    Sims, Rod

    1997-01-01

    This paper promotes further discussion and analysis of interactivity in learning environments and contains a classification of interaction types appropriate for consideration in multimedia settings. Through an examination of related factors associated with navigation and control, a matrix of interactive dimensions is proposed. (Author)

  14. Device-less interaction

    NARCIS (Netherlands)

    Monaci, G.; Triki, M.; Sarroukh, B.E.

    2009-01-01

    This document describes the results of a technology survey for device-less interaction. The Device-less Interaction project (2007-307) aims at providing interaction options for future home appliances without resorting to a remote control or any other dedicated control device. The target home applia

  15. Interaction and Language Acquisition

    Institute of Scientific and Technical Information of China (English)

    孙红叶

    2016-01-01

    Based on Long's Interaction Hypothesis (IH), the paper examines the aspects of interaction that might facilitate natu-ralistic language development and goes further to propose features of interaction that could encourage classroom second lan-guage acquisition, in the hope that improved classroom interation will enhance teaching effectiveness in language classroom.

  16. Dynamic Interactive Learning Systems

    Science.gov (United States)

    Sabry, Khaled; Barker, Jeff

    2009-01-01

    This paper reviews and discusses the notions of interactivity and dynamicity of learning systems in relation to information technologies and design principles that can contribute to interactive and dynamic learning. It explores the concept of dynamic interactive learning systems based on the emerging generation of information as part of a…

  17. Phosphorylation of human Sgo1 by NEK2A is essential for chromosome congression in mitosis

    Institute of Scientific and Technical Information of China (English)

    Guosheng Fu; Xia Ding; Kai Yuan; Felix Aikhionbare; Jianhui Yao; Xin Cai; Kai Jiang; Xuebiao Yao

    2007-01-01

    Chromosome segregation in mitosis is orchestrated by the interaction of the kinetochore with spindle microtubules. Our recent study shows that NEK2A interacts with MAD1 at the kinetochore and possibly functions as a novel integrator of spindle checkpoint signaling. However, it is unclear how NEK2 A regulates kinetochore-microtubule attachment in mitosis. Here we show that NEK2A phosphorylates human Sgol and such phosphorylation is essential for faithful chromosome congression in mitosis. NEK2A binds directly to HsSgol in vitro and co-distributes with HsSgol to the kinetochore of mitotic cells. Our in vitro phosphorylation experiment demonstrated that HsSgol is a substrate of NEK2A and the phosphorylation sites were mapped to Ser14 and Ser507 as judged by the incorporation of 32P. Although such phosphorylation is not required for assembly of HsSgol to the kinetochore, expression of non-phosphorylatable mutant HsSgol perturbed chromosome congression and resulted in a dramatic increase in microtubule attachment errors, including syntelic and monotelic attachments. These findings reveal a key role for the NEK2A-mediated phosphorylation of HsSgol in orchestrating dynamic kinetochore-microtubule interaction. We propose that NEK2A-mediated phosphorylation of human Sgol provides a link between centromeric cohesion and spindle microtubule attachment at the kinetochores.

  18. The Interactive Learning Toolkit: supporting interactive classrooms

    Science.gov (United States)

    Dutta, S.; McCauley, V.; Mazur, E.

    2004-05-01

    Research-based interactive learning techniques have dramatically improved student understanding. We have created the 'Interactive Learning Toolkit' (ILT), a web-based learning management system, to help implement two such pedagogies: Just in Time Teaching and Peer Instruction. Our main goal in developing this toolkit is to save the instructor time and effort and to use technology to facilitate the interaction between the students and the instructor (and between students themselves). After a brief review of both pedagogies, we will demonstrate the many exciting new features of the ILT. We will show how technology can not only implement, but also supplement and improve these pedagogies. We would like acknowdge grants from NSF and DEAS, Harvard University

  19. Food-drug interactions

    DEFF Research Database (Denmark)

    Schmidt, Lars E; Dalhoff, Kim

    2002-01-01

    Interactions between food and drugs may inadvertently reduce or increase the drug effect. The majority of clinically relevant food-drug interactions are caused by food-induced changes in the bioavailability of the drug. Since the bioavailability and clinical effect of most drugs are correlated......, the bioavailability is an important pharmacokinetic effect parameter. However, in order to evaluate the clinical relevance of a food-drug interaction, the impact of food intake on the clinical effect of the drug has to be quantified as well. As a result of quality review in healthcare systems, healthcare providers...... are increasingly required to develop methods for identifying and preventing adverse food-drug interactions. In this review of original literature, we have tried to provide both pharmacokinetic and clinical effect parameters of clinically relevant food-drug interactions. The most important interactions are those...

  20. Grasp interaction with tablets

    CERN Document Server

    Wolf, Katrin

    2015-01-01

    This book presents guidelines for a future device type: a tablet that allows ergonomic front- and back-of-device interaction. These guidelines help designers and developers of user interfaces to build ergonomic applications for tablet devices, in particular for devices that enable back-of-device interaction. In addition, manufacturers of tablet devices obtain arguments that back-of-device interaction is a promising extension of the interaction design space and results in increased input capabilities, enriched design possibilities, and proven usability. The guidelines are derived from empirical studies and developed to fit the users’ skills to the way the novel device type is held. Three particular research areas that are relevant to develop design guidelines for tablet interaction are investigated: ergonomic gestures, interaction areas, and pointing techniques.

  1. Two interacting Hofstadter butterflies

    OpenAIRE

    Barelli, Armelle; Bellissard, Jean; Jacquod, Philippe; Shepelyansky, Dima L.

    1996-01-01

    The problem of two interacting particles in a quasiperiodic potential is addressed. Using analytical and numerical methods, we explore the spectral properties and eigenstates structure from the weak to the strong interaction case. More precisely, a semiclassical approach based on non commutative geometry techniques permits to understand the intricate structure of such a spectrum. An interaction induced localization effect is furthermore emphasized. We discuss the application of our results on...

  2. Interactions in multispecies biofilms

    DEFF Research Database (Denmark)

    Burmølle, Mette; Ren, Dawei; Bjarnsholt, Thomas;

    2014-01-01

    The recent focus on complex bacterial communities has led to the recognition of interactions across species boundaries. This is particularly pronounced in multispecies biofilms, where synergistic interactions impact the bacterial distribution and overall biomass produced. Importantly, in a number...... of settings, the interactions in a multispecies biofilm affect its overall function, physiology, or surroundings, by resulting in enhanced resistance, virulence, or degradation of pollutants, which is of significant importance to human health and activities. The underlying mechanisms causing these synergistic...

  3. Interactive Strategy-Making

    DEFF Research Database (Denmark)

    Andersen, Torben Juul

    2015-01-01

    to failed communication and execution of the planned actions. However, effective strategy-making comprises both central reasoning from forward-looking planning considerations and decentralised responses to emerging events as interacting elements in a dynamic adaptive system. The interaction between......This article outlines an interactive strategy-making model that combines central reasoning with ongoing learning from decentralised responses. The management literature often presents strategy as implementing an optimal plan identified through rational analysis and ascribes potential shortcomings...

  4. Quantum interaction. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Bruza, Peter [Queensland Univ. of Technology, Brisbane (Australia). Faculty of Science and Technology; Sofge, Donald [Navy Center for Applied Research in Artificial Intelligence, Washington, DC (United States). Naval Research Lab.; Lawless, William [Paine Coll., Augusta, GA (United States); Rijsbergen, Keith van [Glasgow Univ. (United Kingdom). Dept. of Computing Science; Klusch, Matthias (eds.) [German Research Center for Artificial Intelligence, Saarbruecken (Germany)

    2009-07-01

    This book constitutes the refereed proceedings of the Third International Symposium on Quantum Interaction, QI 2009, held in Saarbruecken, Germany, in March 2009. The 21 revised full papers presented together with the 3 position papers were carefully reviewed and selected from numerous submissions. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, decision theory, information retrieval, information systems, social interaction, computational linguistics and finance. (orig.)

  5. Two interacting Hofstadter butterflies

    Energy Technology Data Exchange (ETDEWEB)

    Barelli, A.; Bellissard, J. [Laboratoire de Physique Quantique, UMR 5626 du CNRS, Universite Paul Sabatier, F-31062 Toulouse Cedex (France); Jacquod, P. [Institut de Physique, Universite de Neuchatel, CH-2000 Neuchatel (Switzerland), Confederation Helvetique; Shepelyansky, D.L. [Laboratoire de Physique Quantique, UMR 5626 du CNRS, Universite Paul Sabatier, F-31062 Toulouse Cedex (France)

    1997-04-01

    The problem of two interacting particles in a quasiperiodic potential is addressed. Using analytical and numerical methods, we explore the spectral properties and eigenstates structure from the weak to the strong interaction case. More precisely, a semiclassical approach based on noncommutative geometry techniques is used to understand the intricate structure of such a spectrum. An interaction induced localization effect is furthermore emphasized. We discuss the application of our results on a two-dimensional model of two particles in a uniform magnetic field with on-site interaction. {copyright} {ital 1997} {ital The American Physical Society}

  6. Framing interactive methods

    DEFF Research Database (Denmark)

    2011-01-01

    Two paradigms of organization and leadership is outlined and compared. A theoretical model of interactive leadership is developed, combining learning, knowledge flow, leadership and organizational principles....

  7. Philosophy of Interaction

    DEFF Research Database (Denmark)

    Svanæs, Dag

    2011-01-01

    This is an encyclopedia entry for the Interaction-Design.org free IxD encyclopedia. The topic of the entry is the application of the philosophy of Heidegger and Merleau-Ponty to a theory of interactivity. Comments by Don Norman and Eva Hornecker.......This is an encyclopedia entry for the Interaction-Design.org free IxD encyclopedia. The topic of the entry is the application of the philosophy of Heidegger and Merleau-Ponty to a theory of interactivity. Comments by Don Norman and Eva Hornecker....

  8. Vision-based interaction

    CERN Document Server

    Turk, Matthew

    2013-01-01

    In its early years, the field of computer vision was largely motivated by researchers seeking computational models of biological vision and solutions to practical problems in manufacturing, defense, and medicine. For the past two decades or so, there has been an increasing interest in computer vision as an input modality in the context of human-computer interaction. Such vision-based interaction can endow interactive systems with visual capabilities similar to those important to human-human interaction, in order to perceive non-verbal cues and incorporate this information in applications such

  9. Proxemic Mobile Collocated Interactions

    DEFF Research Database (Denmark)

    Porcheron, Martin; Lucero, Andrés; Quigley, Aaron

    2016-01-01

    and their digital devices (i.e. the proxemic relationships). Building on the ideas of proxemic interactions, this workshop is motivated by the concept of ‘proxemic mobile collocated interactions’, to harness new or existing technologies to create engaging and interactionally relevant experiences. Such approaches......Recent research on mobile collocated interactions has been looking at situations in which collocated users engage in collaborative activities using their mobile devices. However, existing practices fail to fully account for the culturally-dependent spatial relationships between people...... in exploring proxemics and mobile collocated interactions....

  10. Drug-nutrient interactions.

    Science.gov (United States)

    Chan, Lingtak-Neander

    2013-07-01

    Drug-nutrient interactions are defined as physical, chemical, physiologic, or pathophysiologic relationships between a drug and a nutrient. The causes of most clinically significant drug-nutrient interactions are usually multifactorial. Failure to identify and properly manage drug-nutrient interactions can lead to very serious consequences and have a negative impact on patient outcomes. Nevertheless, with thorough review and assessment of the patient's history and treatment regimens and a carefully executed management strategy, adverse events associated with drug-nutrient interactions can be prevented. Based on the physiologic sequence of events after a drug or a nutrient has entered the body and the mechanism of interactions, drug-nutrient interactions can be categorized into 4 main types. Each type of interaction can be managed using similar strategies. The existing data that guide the clinical management of most drug-nutrient interactions are mostly anecdotal experience, uncontrolled observations, and opinions, whereas the science in understanding the mechanism of drug-nutrient interactions remains limited. The challenge for researchers and clinicians is to increase both basic and higher level clinical research in this field to bridge the gap between the science and practice. The research should aim to establish a better understanding of the function, regulation, and substrate specificity of the nutrient-related enzymes and transport proteins present in the gastrointestinal tract, as well as assess how the incidence and management of drug-nutrient interactions can be affected by sex, ethnicity, environmental factors, and genetic polymorphisms. This knowledge can help us develop a true personalized medicine approach in the prevention and management of drug-nutrient interactions.

  11. Three wise centromere functions: see no error, hear no break, speak no delay.

    Science.gov (United States)

    Tanaka, Tomoyuki U; Clayton, Lesley; Natsume, Toyoaki

    2013-12-01

    The main function of the centromere is to promote kinetochore assembly for spindle microtubule attachment. Two additional functions of the centromere, however, are becoming increasingly clear: facilitation of robust sister-chromatid cohesion at pericentromeres and advancement of replication of centromeric regions. The combination of these three centromere functions ensures correct chromosome segregation during mitosis. Here, we review the mechanisms of the kinetochore-microtubule interaction, focusing on sister-kinetochore bi-orientation (or chromosome bi-orientation). We also discuss the biological importance of robust pericentromeric cohesion and early centromere replication, as well as the mechanisms orchestrating these two functions at the microtubule attachment site.

  12. Child Computer Interaction SIG

    DEFF Research Database (Denmark)

    Read, Janet; Hourcade, Juan Pablo; Markopoulos, Panos

    The discipline of Child Computer Interaction (CCI) has been steadily growing and it is now firmly established as a community in its own right, having the annual IDC (Interaction and Design for Children) conference and its own journal and also enjoying its role as a highly recognisable and vibrant...

  13. Visualizing Dispersion Interactions

    Science.gov (United States)

    Gottschalk, Elinor; Venkataraman, Bhawani

    2014-01-01

    An animation and accompanying activity has been developed to help students visualize how dispersion interactions arise. The animation uses the gecko's ability to walk on vertical surfaces to illustrate how dispersion interactions play a role in macroscale outcomes. Assessment of student learning reveals that students were able to develop…

  14. Progress on Multiple Interactions

    CERN Document Server

    Skands, P Z

    2004-01-01

    We report on the development of a new model for the underlying event in hadron-hadron collisions. The model includes parton showers for all interactions, as well as non-trivial flavour, momentum, and colour correlations between interaction initiators and beam remnant partons.

  15. Moving into an interaction

    DEFF Research Database (Denmark)

    Mortensen, Kristian; Hazel, Spencer

    2014-01-01

    Opening an interaction is a crucial step in establishing and maintaining social relationships. In this paper we describe how participants in an institutional setting, a help desk counter for exchange students at an international university, literally move into interaction. This is accomplished...

  16. INTERACT Station Catalogue - 2015

    DEFF Research Database (Denmark)

    INTERACT stations are located in all major environmental envelopes of the Arctic providing an ideal platform for studying climate change and its impact on the environment and local communities. Since alpine environments face similar changes and challenges as the Arctic, the INTERACT network also ...

  17. Storyboarding Multimedia Interactions.

    Science.gov (United States)

    Martin, Linda C.

    2000-01-01

    Understanding how to include interactivity when designing multimedia-based training (MBT) storyboards is a major key for a successful MBT. Discusses the basic formats of interactions and when to use each format. Describes how to storyboard and areas to address, including: the display area, prompts, branching, programming and graphics notes,…

  18. Interactive Visualization of Dependencies

    Science.gov (United States)

    Moreno, Camilo Arango; Bischof, Walter F.; Hoover, H. James

    2012-01-01

    We present an interactive tool for browsing course requisites as a case study of dependency visualization. This tool uses multiple interactive visualizations to allow the user to explore the dependencies between courses. A usability study revealed that the proposed browser provides significant advantages over traditional methods, in terms of…

  19. Magnetic interactions between nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Hansen, Mikkel Fougt; Frandsen, Cathrine

    2010-01-01

    We present a short overview of the influence of inter-particle interactions on the properties of magnetic nanoparticles. Strong magnetic dipole interactions between ferromagnetic or ferrimagnetic particles, that would be superparamagnetic if isolated, can result in a collective state...... of nanoparticles. This collective state has many similarities to spin-glasses. In samples of aggregated magnetic nanoparticles, exchange interactions are often important and this can also lead to a strong suppression of superparamagnetic relaxation. The temperature dependence of the order parameter in samples...... of strongly interacting hematite nanoparticles or goethite grains is well described by a simple mean field model. Exchange interactions between nanoparticles with different orientations of the easy axes can also result in a rotation of the sub-lattice magnetization directions....

  20. Laser-surface interactions

    CERN Document Server

    Ganeev, Rashid A

    2014-01-01

    This book is about the interaction of laser radiation with various surfaces at variable parameters of radiation. As a basic principle of classification we chose the energetic or intensity level of interaction of laser radiation with the surfaces. These two characteristics of laser radiation are the most important parameters defining entire spectrum of the processes occurring on the surfaces during interaction with electromagnetic waves. This is a first book containing a whole spectrum of the laser-surface interactions distinguished by the ranges of used laser intensity. It combines the surface response starting from extremely weak laser intensities (~1 W cm-2) up to the relativistic intensities (~1020 W cm-2 and higher). The book provides the basic information about lasers and acquaints the reader with both common applications of laser-surface interactions (laser-related printers, scanners, barcode readers, discs, material processing, military, holography, medicine, etc) and unusual uses of the processes on t...

  1. Human Work Interaction Design

    DEFF Research Database (Denmark)

    Lopes, Arminda; Ørngreen, Rikke

    This book constitutes the thoroughly refereed post-conference proceedings of the Third IFIP WG 13.6 Working Conference on Human Work Interaction Design, HWID 2012, held in Copenhagen, Denmark, in December 2012. The 16 revised papers presented were carefully selected for inclusion in this volume. ......, and mobile probing. They have been organized in the following topical sections: work analysis: dimensions and methods; interactions, models and approaches; and evaluations, interactions and applications.......This book constitutes the thoroughly refereed post-conference proceedings of the Third IFIP WG 13.6 Working Conference on Human Work Interaction Design, HWID 2012, held in Copenhagen, Denmark, in December 2012. The 16 revised papers presented were carefully selected for inclusion in this volume....... The papers reflect many different areas and address many complex and diverse work domains, ranging from medical user interfaces, work and speech interactions at elderly care facilities, greenhouse climate control, navigating through large oil industry engineering models, crisis management, library usability...

  2. Extrasolar Planet Interactions

    CERN Document Server

    Barnes, Rory

    2008-01-01

    The dynamical interactions of planetary systems may be a clue to their formation histories. Therefore, the distribution of these interactions provides important constraints on models of planet formation. We focus on each system's apsidal motion and proximity to dynamical instability. Although only ~25 multiple planet systems have been discovered to date, our analyses in these terms have revealed several important features of planetary interactions. 1) Many systems interact such that they are near the boundary between stability and instability. 2) Planets tend to form such that at least one planet's eccentricity periodically drops to near zero. 3) Mean-motion resonant pairs would be unstable if not for the resonance. 4) Scattering of approximately equal mass planets is unlikely to produce the observed distribution of apsidal behavior. 5) Resonant interactions may be identified through calculating a system's proximity to instability, regardless of knowledge of angles such as mean longitude and longitude of peri...

  3. DNA topoisomerase II is a determinant of the tensile properties of yeast centromeric chromatin and the tension checkpoint.

    Science.gov (United States)

    Warsi, Tariq H; Navarro, Michelle S; Bachant, Jeff

    2008-10-01

    Centromeric (CEN) chromatin is placed under mechanical tension and stretches as kinetochores biorient on the mitotic spindle. This deformation could conceivably provide a readout of biorientation to error correction mechanisms that monitor kinetochore-spindle interactions, but whether CEN chromatin acts in a tensiometer capacity is unresolved. Here, we report observations linking yeast Topoisomerase II (Top2) to both CEN mechanics and assessment of interkinetochore tension. First, in top2-4 and sumoylation-resistant top2-SNM mutants CEN chromatin stretches extensively during biorientation, resulting in increased sister kinetochore separation and preanaphase spindle extension. Our data indicate increased CEN stretching corresponds with alterations to CEN topology induced in response to tension. Second, Top2 potentiates aspects of the tension checkpoint. Mutations affecting the Mtw1 kinetochore protein activate Ipl1 kinase to detach kinetochores and induce spindle checkpoint arrest. In mtw1top2-4 and mtw1top2-SNM mutants, however, kinetochores are resistant to detachment and checkpoint arrest is attenuated. For top2-SNM cells, CEN stretching and checkpoint attenuation occur even in the absence of catenation linking sister chromatids. In sum, Top2 seems to play a novel role in CEN compaction that is distinct from decatenation. Perturbations to this function may allow weakened kinetochores to stretch CENs in a manner that mimics tension or evades Ipl1 surveillance.

  4. Interaction English Teaching Model

    Institute of Scientific and Technical Information of China (English)

    穆宇娜

    2013-01-01

      Malash—Thomas pointed out“Interaction is a process in which people and things act upon each other through their ac⁃tions.”According to different subjects, interaction can be divided into human-computer interaction, people-people interaction and learner-content interaction. According to different forms, interactions can be divided into one-one interaction, one-more interac⁃tion and more-more interaction.“Interaction Education”means that teachers are leading parts and students are the center of class. During teaching process, teachers must lead students to discover. Demands from students can encourage teachers to inspire con⁃versely.Thus it can form a close communication between teachers and students. Teaching and learning are realized in a happy and harmonious atmosphere. Successful English teaching must take new bilateral teaching as the first part, which should let the func⁃tion of the two most important elements develop fully. Teachers should grasp opportunities to guide. Teaching methods need to be flexible, and contents of teaching need to be vivid;students should be keen to think, to participate actively, and can break the tradi⁃tion to produce fresh ideas, and in that situation the capability of students can develop fully. The educational model refers to the simplified description of detailed teaching activities. Possessing dual functions of theory and practice, the educational model is the manifestation of theoretical teaching method. The combination of interaction and educational model which are mentioned above form the“interactive teaching”model. With the coming of economic globalization and integration of science and technology, now communications are increasing with each passing day. If you want to take part in or to get in touch with others, you must use lan⁃guage. English has been learnt for 10 years in Middle school and in college, but it can’t be spoken very fluently. That is a realistic picture as the result of an

  5. Sketches in Embodied Interaction

    DEFF Research Database (Denmark)

    Erkut, Cumhur; Dahl, Sofia; Triantafyllidis, Georgios

    2014-01-01

    We present an approach for teaching and designing embodied interaction based on interactive sketches. We have combined the mover perspective and felt experiences of movement with advanced technologies (multi-agents, physical simulations) in a generative design session. We report our activities...... and provide a simple example as a design outcome. The variety and the qualities of the initial ideas indicate that this approach might provide a better foundation for our participants, compared to the approaches that focus only on technologies. The interactive sketches were demonstrated at the conference....

  6. Media Facades beyond Interaction

    DEFF Research Database (Denmark)

    Fritsch, Jonas

    2008-01-01

    As part of a the research project Digital Urban Living [www.digitalurbanliving.dk], we have taken part in the design of two large-scale installations that employ interactive technologies to facilitate participation and foster social interactions in public, urban settings. We present the two cases......, Aarhus by Light and Projected Poetry, and discuss the future trajectory of our work in this field, as well as some of our findings regarding the challenges of designing large-scale public interactive installations. In doing so, we specifically highlight the possibilities in relation to designing...

  7. Dendrimer-surfactant interactions.

    Science.gov (United States)

    Cheng, Yiyun; Zhao, Libo; Li, Tianfu

    2014-04-28

    In this article, we reviewed the interactions between dendrimers and surfactants with particular focus on the interaction mechanisms and physicochemical properties of the yielding dendrimer-surfactant aggregates. In order to provide insight into the behavior of dendrimers in biological systems, the interactions of dendrimers with bio-surfactants such as phospholipids in bulk solutions, in solid-supported bilayers and at the interface of phases or solid-states were discussed. Applications of the dendrimer-surfactant aggregates as templates to guide the synthesis of nanoparticles and in drug or gene delivery were also mentioned.

  8. Chasing Ecological Interactions

    Science.gov (United States)

    2016-01-01

    Basic research on biodiversity has concentrated on individual species—naming new species, studying distribution patterns, and analyzing their evolutionary relationships. Yet biodiversity is more than a collection of individual species; it is the combination of biological entities and processes that support life on Earth. To understand biodiversity we must catalog it, but we must also assess the ways species interact with other species to provide functional support for the Tree of Life. Ecological interactions may be lost well before the species involved in those interactions go extinct; their ecological functions disappear even though they remain. Here, I address the challenges in studying the functional aspects of species interactions and how basic research is helping us address the fast-paced extinction of species due to human activities. PMID:27631692

  9. Interaction Before Agriculture

    DEFF Research Database (Denmark)

    Richter, Tobias; Garrard, Andrew; Allcock, Samantha

    2011-01-01

    This article discusses social interaction in the Epipalaeolithic of southwest Asia. Discussions of contact, social relationships and social organization have primarily focused on the Pre-Pottery Neolithic and are often considered to represent typical hallmarks of emergent farming societies...

  10. Interactive Office user's manual

    Science.gov (United States)

    Montgomery, Edward E.; Lowers, Benjamin; Nabors, Terri L.

    1990-01-01

    Given here is a user's manual for Interactive Office (IO), an executive office tool for organization and planning, written specifically for Macintosh. IO is a paperless management tool to automate a related group of individuals into one productive system.

  11. ENTREPRENEURSHIP AS SOCIAL INTERACTION

    DEFF Research Database (Denmark)

    Larsen, Henry; Lima, Patricia; Olsen, Bente

    2013-01-01

    This paper aims to explore how entrepreneurs work with innovation; to explore and develop attention points in understanding entrepreneurship as social processes of interaction between people. Through interviews and engagement with entrepreneurs and key stakeholders, their actual social practices...... and the influence on the progress as innovators are explored. It is focused on a new local activity in a Danish town, named the I-factory which has within a year gathered almost 40 entrepreneurs. As a part of the interaction, there were created activities to encourage even more collaboration. We see...... entrepreneurship as socially constructed through local interactions between players and identify key themes in these interactions within the organisation, such as leadership, becoming part of the initiative and trust/mistrust. By doing so, this paper contributes to an understanding of entrepreneurship as social...

  12. Atomic & Molecular Interactions

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-07-12

    The Gordon Research Conference (GRC) on Atomic & Molecular Interactions was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  13. Space for Interaction

    DEFF Research Database (Denmark)

    Jørgensen, Mariane Ellen; Folmer, Mette Blicher; Mullins, Michael

    SPACE FOR INTERACTION QUALIFYING GROUP TREATMENT FOR PATIENTS WITH CHRONIC PAIN THROUGH OPTIMIZATION(?) OF SPACE. A RANDOMIZED PILOT STUDY. In a Ph-D. Mariane Ellen Jørgensen / Nurse + psykoterapist / maej@rn.dk / Pain Center / Aalborg University Hospital / Denmark / Mette Blicher Folmer...... Building Research Institute / Aalborg University / Denmark AIM Research shows the hospital space has significance for human healing processes and the physical environment can have both positive and negative impact on the interaction between patients and staff. In order to qualify treatment for patients...... with chronic pain, the effect and experience of two different rooms for group therapy were compared. Three hypotheses were tested: 1) Room decor affects the interaction and thus the psychotherapeutic group therapy 2) The meaning of space for the interaction could be measured on the effect of treatment 3...

  14. Patient - patient interaction

    DEFF Research Database (Denmark)

    Birkelund, Regner; Søndergaard Larsen, Lene

    2013-01-01

    Aim:  The aim of this study is to provide an understanding of the significance of hospitalized patients’ interpersonal interaction with fellow patients in an infectious disease ward in a large Danish hospital. Method:  A qualitative approach was selected using participant observation and semi...... subcategories representing significance of patients’ interaction with fellow patients. Results:  The qualitative analysis resulted in two main categories: (i) Caring for fellow patients and (ii) Sharing illness information with fellow patients. Each of the main categories was elucidated through several...... subcategories. Our findings clearly showed that interpersonal interaction with fellow patients was of utmost importance when it came to care and support and when they needed information about their illness. Typically, the interpersonal interaction was experienced as giving and referred to in positive terms...

  15. Unparticle self-interactions

    CERN Document Server

    Georgi, Howard

    2009-01-01

    We develop techniques for studying the effects of self-interactions in the conformal sector of an unparticle model. Their physics is encoded in the higher n-point functions of the conformal theory. We study inclusive processes and argue that the inclusive production of unparticle stuff in standard model processes due to the unparticle self-interactions can be decomposed using the conformal partial wave expansion and its generalizations into a sum over contributions from the production of various kinds of unparticle stuff, corresponding to different primary conformal operators. Such processes typically involve the production of unparticle stuff associated with operators other than those to which the standard model couples directly. Thus just as interactions between particles allow scattering processes to produce new particles in the final state, so unparticle self-interactions cause the production of various kinds of unparticle stuff. We discuss both inclusive and exclusive methods for computing these processe...

  16. Theory of gravitational interactions

    CERN Document Server

    Gasperini, Maurizio

    2013-01-01

    This reference textbook is an up-to-date and self-contained introduction to the theory of gravitational interactions. The first part of the book follows the traditional presentation of general relativity as a geometric theory of the macroscopic gravitational field. A second, advanced part then discusses the deep analogies (and differences) between a geometric theory of gravity and the gauge theories of the other fundamental interactions. This fills a gap which is present in the context of the traditional approach to general relativity, and which usually makes students puzzled about the role of gravity. The necessary notions of differential geometry are reduced to the minimum, leaving more room for those aspects of gravitational physics of current phenomenological and theoretical interest, such as the properties of gravitational waves, the gravitational interactions of spinors, and the supersymmetric and higher-dimensional generalization of the Einstein equations. Theory of Gravitational Interactions will be o...

  17. Interactive Sample Book (ISB)

    DEFF Research Database (Denmark)

    Heimdal, Elisabeth Jacobsen; Lenau, Torben Anker; Guglielmi, Michel

    2009-01-01

    involving designers and engineers. It is carried out by Elisabeth Heimdal as her Master thesis from Design & Innovation, The Technical University of Denmark. Collaboration partners are the design bureau Diffus, textile designer Priya Mani, master student in medialogy at AAU Marija Andonovska and DTU......, with the aim of exploring and communicating some of the possibilities within interactive textiles. The applications for interactive textiles range from medical applications to architecture, and from the fashion industry to costume design. In relation to the sample book, focus will be on texture, lightning...... and senses in relation to integrated decoration and function primarily to indoor applications. The result of the project will be a number of interactive textiles, to be gathered in an interactive sample book (ISB), in a similar way as the sample books of wallpapers one can take home from the shop and choose...

  18. Neutrino Self-Interactions

    CERN Document Server

    Hasenkamp, Jasper

    2016-01-01

    We propose a theory that equips the active neutrinos with interactions among themselves that are at least three orders of magnitude stronger than the weak interaction. We introduce an Abelian gauge group $U(1)_x$ with vacuum expectation value $v_x \\lesssim \\mathcal{O}(100 \\textrm{ MeV})$. An asymmetric mass matrix implements the active neutrinos as massless mass eigenstates carrying "effective" charges. To stabilize $v_x$, supersymmetry breaking is mediated via loops to the additional sector with the only exception of xHiggs terms. No Standard Model interaction eigenstate carries $U(1)_x$ charge. Thus the dark photon's kinetic mixing is two-loop suppressed.With only simple and generic values of dimensionless parameters, our theory might explain the high-energy neutrino spectrum observed by IceCube including the PeV neutrinos. We comment on the imposing opportunity to incorporate a self-interacting dark matter candidate.

  19. Interactive Energy Planning

    DEFF Research Database (Denmark)

    Blarke, Morten Boje

    2006-01-01

    anchoring along the shores of the land of communications and collaboration. Whether or not a particular typology is applicable, theory and praxis are establishing standpoints, which strengthens our understanding of the planning complex, and which should inspire improved energy planning methodologies...... and tools. This paper presents an “Interactive Energy Planning” framework, which is intended to support interactivity in planning, building on important theoretical and experimental advances in planning. In particular, the paper explores the potential significance of allowing a critical perspective...... on context analysis and problem-orientation to define the course of the planning process, and deploying value-rational planning tools primarily as a platform for interactivity. The focus on interactivity in energy planning will allow contemporary government planners, consultants, researchers...

  20. Mobile Collocated Interactions

    DEFF Research Database (Denmark)

    Lucero, Andrés; Clawson, James; Lyons, Kent

    2015-01-01

    Mobile devices such as smartphones and tablets were originally conceived and have traditionally been utilized for individual use. Research on mobile collocated interactions has been looking at situations in which collocated users engage in collaborative activities using their mobile devices, thus...... going from personal/individual toward shared/multiuser experiences and interactions. However, computers are getting smaller, more powerful, and closer to our bodies. Therefore, mobile collocated interactions research, which originally looked at smartphones and tablets, will inevitably include ever......-smaller computers, ones that can be worn on our wrists or other parts of the body. The focus of this workshop is to bring together a community of researchers, designers and practitioners to explore the potential of extending mobile collocated interactions to the use of wearable devices....

  1. Interaction as Negotiation

    DEFF Research Database (Denmark)

    Kristensen, Jannie Friis; Nielsen, Christina

    In this paper we discuss recent developments in interaction design principles for ubiquitous computing environments, specifically implications related to situated and mobile aspects of work. We present 'Interaction through Negotiation' as a general Human-Computer Interaction (HCI) paradigm, aimed...... at ubiquitous/pervasive technology and environments, with focus on facilitating negotiation in and between webs of different artifacts, humans and places. This approach is concerned with the way technology presents itself to us, both as physical entities and as conceptual entities, as well as the relations...... on several extensive empirical case studies, as well as co-operative design-sessions, we present a reflective analysis providing insights into results of the "Interaction through Negotiation" design approach in action. A very promising area of application is exception handling in pervasive computing...

  2. Interactive Biplot Construction

    OpenAIRE

    Frederic Udina

    2005-01-01

    We analyze and discuss how a generic software to produce biplot graphs should be designed. We describe a data structure appropriate to include the biplot description and we specify the algorithm(s) to be used for several biplot types. We discuss the options the software should offer to the user in two different environments. In a highly interactive environment the user should be able to specify many graphical options and also to change them using the usual interactive tools. The resulting gra...

  3. Interacting Agegraphic Dark Energy

    OpenAIRE

    Wei, Hao; Cai, Rong-Gen

    2007-01-01

    A new dark energy model, named "agegraphic dark energy", has been proposed recently, based on the so-called K\\'{a}rolyh\\'{a}zy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegrap...

  4. Human-machine interactions

    Science.gov (United States)

    Forsythe, J. Chris; Xavier, Patrick G.; Abbott, Robert G.; Brannon, Nathan G.; Bernard, Michael L.; Speed, Ann E.

    2009-04-28

    Digital technology utilizing a cognitive model based on human naturalistic decision-making processes, including pattern recognition and episodic memory, can reduce the dependency of human-machine interactions on the abilities of a human user and can enable a machine to more closely emulate human-like responses. Such a cognitive model can enable digital technology to use cognitive capacities fundamental to human-like communication and cooperation to interact with humans.

  5. Quantum interaction. Selected papers

    Energy Technology Data Exchange (ETDEWEB)

    Atmanspacher, Harald [Eidgenoessische Technische Hochschule, Zurich (Switzerland); Haven, Emmanuel [Leicester Univ. (United Kingdom). School of Management; Kitto, Kirsty [Queensland Univ. of Technology, Brisbane, QLD (Australia); Raine, Derek (ed.) [Leicester Univ. (United Kingdom). Centre for Interdisciplinary Science

    2014-07-01

    This book constitutes the refereed proceedings of the 7th International Conference on Quantum Interaction, QI 2013, held in Leicester, UK, in July 2013. The 31 papers presented in this book were carefully selected from numerous submissions. The papers cover various topics on quantum interaction and revolve around four themes: information processing/retrieval/semantic representation and logic; cognition and decision making; finance/economics and social structures and biological systems.

  6. Interaction with geospatial data

    OpenAIRE

    SCHOENING, Johannes

    2015-01-01

    My research interest lies at the interaction between human-computer interaction (HCI) and geoinformatics. I am interested in developing new methods and novel user interfaces to navigate through spatial information. This article will give a brief overview on my past and current research topics and streams. Generally speaking, geography is playing an increasingly important role in computer science and also in the field of HCI ranging from social computing to natural user interfaces (NUIs). At t...

  7. Beam-Material Interaction

    Energy Technology Data Exchange (ETDEWEB)

    Mokhov, N. V. [Fermilab; Cerutti, F. [CERN

    2016-01-01

    Th is paper is motivated by the growing importance of better understanding of the phenomena and consequences of high-intensity energetic particle beam interactions with accelerator, generic target, and detector components. It reviews the principal physical processes of fast-particle interactions with matter, effects in materials under irradiation, materials response, related to component lifetime and performance, simulation techniques, and methods of mitigating the impact of radiation on the components and environment in challenging current and future applications.

  8. Extrasolar planet interactions

    Science.gov (United States)

    Barnes, Rory; Greenberg, Richard

    2008-05-01

    The dynamical interactions of planetary systems may be a clue to their formation histories. Therefore, the distribution of these interactions provides important constraints on models of planet formation. We focus on each system's apsidal motion and proximity to dynamical instability. Although only 25 multiple planet systems have been discovered to date, our analyses in these terms have revealed several important features of planetary interactions. 1) Many systems interact such that they are near the boundary between stability and instability. 2) Planets tend to form such that at least one planet's eccentricity periodically drops to near zero. 3) Mean-motion resonant pairs would be unstable if not for the resonance. 4) Scattering of approximately equal mass planets is unlikely to produce the observed distribution of apsidal behavior. 5) Resonant interactions may be identified through calculating a system's proximity to instability, regardless of knowledge of angles such as mean longitude and longitude of periastron (e.g. GJ 317 b and c are probably in a 4:1 resonance). These properties of planetary systems have been identified through calculation of two parameters that describe the interaction. The apsidal interaction can be quantified by determining how close a planet is to an apsidal separatrix (a boundary between qualitatively different types of apsidal oscillations, e.g. libration or circulation of the major axes). This value can be calculated through short numerical integrations. The proximity to instability can be measured by comparing the observed orbital elements to an analytic boundary that describes a type of stability known as Hill stability. We have set up a website dedicated to presenting the most up-to-date information on dynamical interactions: http://www.lpl.arizona.edu/~rory/research/xsp/dynamics.

  9. Beam-Material Interaction

    CERN Document Server

    Mokhov, N.V.

    2016-01-01

    Th is paper is motivated by the growing importance of better understanding of the phenomena and consequences of high- intensity energetic particle beam interactions with accelerator, generic target , and detector components. It reviews the principal physical processes of fast-particle interactions with matter, effects in materials under irradiation, materials response, related to component lifetime and performance, simulation techniques, and methods of mitigating the impact of radiation on the components and envir onment in challenging current and future application

  10. Sperm-egg interaction.

    Science.gov (United States)

    Evans, Janice P

    2012-01-01

    A crucial step of fertilization is the sperm-egg interaction that allows the two gametes to fuse and create the zygote. In the mouse, CD9 on the egg and IZUMO1 on the sperm stand out as critical players, as Cd9(-/-) and Izumo1(-/-) mice are healthy but infertile or severely subfertile due to defective sperm-egg interaction. Moreover, work on several nonmammalian organisms has identified some of the most intriguing candidates implicated in sperm-egg interaction. Understanding of gamete membrane interactions is advancing through characterization of in vivo and in vitro fertilization phenotypes, including insights from less robust phenotypes that highlight potential supporting (albeit not absolutely essential) players. An emerging theme is that there are varied roles for gamete molecules that participate in sperm-egg interactions. Such roles include not only functioning as fusogens, or as adhesion molecules for the opposite gamete, but also functioning through interactions in cis with other proteins to regulate membrane order and functionality.

  11. The spatial arrangement of chromosomes during prometaphase facilitates spindle assembly.

    Science.gov (United States)

    Magidson, Valentin; O'Connell, Christopher B; Lončarek, Jadranka; Paul, Raja; Mogilner, Alex; Khodjakov, Alexey

    2011-08-19

    Error-free chromosome segregation requires stable attachment of sister kinetochores to the opposite spindle poles (amphitelic attachment). Exactly how amphitelic attachments are achieved during spindle assembly remains elusive. We employed photoactivatable GFP and high-resolution live-cell confocal microscopy to visualize complete 3D movements of individual kinetochores throughout mitosis in nontransformed human cells. Combined with electron microscopy, molecular perturbations, and immunofluorescence analyses, this approach reveals unexpected details of chromosome behavior. Our data demonstrate that unstable lateral interactions between kinetochores and microtubules dominate during early prometaphase. These transient interactions lead to the reproducible arrangement of chromosomes in an equatorial ring on the surface of the nascent spindle. A computational model predicts that this toroidal distribution of chromosomes exposes kinetochores to a high density of microtubules which facilitates subsequent formation of amphitelic attachments. Thus, spindle formation involves a previously overlooked stage of chromosome prepositioning which promotes formation of amphitelic attachments.

  12. 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.

  13. Interactions between photodegradation components

    Directory of Open Access Journals (Sweden)

    Abdollahi Yadollah

    2012-09-01

    Full Text Available Abstract Background The interactions of p-cresol photocatalytic degradation components were studied by response surface methodology. The study was designed by central composite design using the irradiation time, pH, the amount of photocatalyst and the p-cresol concentration as variables. The design was performed to obtain photodegradation % as actual responses. The actual responses were fitted with linear, two factor interactions, cubic and quadratic model to select an appropriate model. The selected model was validated by analysis of variance which provided evidences such as high F-value (845.09, very low P-value (2 = 0.999, adjusted R-squared (Radj2 = 0.998, predicted R-squared (Rpred2 = 0.994 and the adequate precision (95.94. Results From the validated model demonstrated that the component had interaction with irradiation time under 180 min of the time while the interaction with pH was above pH 9. Moreover, photocatalyst and p-cresol had interaction at minimal amount of photocatalyst (p-cresol. Conclusion These variables are interdependent and should be simultaneously considered during the photodegradation process, which is one of the advantages of the response surface methodology over the traditional laboratory method.

  14. Strongly interacting Fermi gases

    Directory of Open Access Journals (Sweden)

    Bakr W.

    2013-08-01

    Full Text Available Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly, we discuss high-precision measurements on the thermodynamics of a strongly interacting Fermi gas across the superfluid transition. The onset of superfluidity is directly observed in the compressibility, the chemical potential, the entropy, and the heat capacity. Our measurements provide benchmarks for current many-body theories on strongly interacting fermions. Secondly, we have studied the evolution of fermion pairing from three to two dimensions in these gases, relating to the physics of layered superconductors. In the presence of p-wave interactions, Fermi gases are predicted to display toplogical superfluidity carrying Majorana edge states. Two possible avenues in this direction are discussed, our creation and direct observation of spin-orbit coupling in Fermi gases and the creation of fermionic molecules of 23Na 40K that will feature strong dipolar interactions in their absolute ground state.

  15. Interactive Karyotyping Training

    Directory of Open Access Journals (Sweden)

    Ashwin Kotwaliwale

    2013-01-01

    Full Text Available Despite the wide use of newer techniques in genetic diagnostics, there remains a need for technologists to learn human chromosome morphology, identify abnormal metaphases and report clinical abnormalities. Global short age of cytogenetic trainers and a time consuming training process makes Karyotyping training difficult. We have developed a web based interactive Karyotyping training tool, KaryoTutor©, that allows technologists to learn karyotyping in an interactive environment and aids the trainer in the training process. KaryoTutor©provides visual clues for identifying abnormal chromosomes, provides instant test scores and includes a reference library of ideograms,sample chromosome images and reference materials. Trainees are able to recursively work on a case till a satisfactory result is achieved,with KaryoTutor providing interactive inputs.Additionally, trainers can assign cases and monitor trainee progress using audit trail management and other administrative features.

  16. Sonic Interaction Design

    DEFF Research Database (Denmark)

    created for such contexts as mobile music, sensorimotor learning, rehabilitation, and gaming. The goal is not only to extend the existing research and pedagogical approaches to SID but also to foster domains of practice for sound designers, architects, interaction designers, media artists, product......Sound is an integral part of every user experience but a neglected medium in design disciplines. Design of an artifact’s sonic qualities is often limited to the shaping of functional, representational, and signaling roles of sound. The interdisciplinary field of sonic interaction design (SID...... aspects of sonic experience. Sonic Interaction Design gathers contributions from scholars, artists, and designers working at the intersections of fields ranging from electronic music to cognitive science. They offer both theoretical considerations of key themes and case studies of products and systems...

  17. Gene-environment interaction.

    Science.gov (United States)

    Manuck, Stephen B; McCaffery, Jeanne M

    2014-01-01

    With the advent of increasingly accessible technologies for typing genetic variation, studies of gene-environment (G×E) interactions have proliferated in psychological research. Among the aims of such studies are testing developmental hypotheses and models of the etiology of behavioral disorders, defining boundaries of genetic and environmental influences, and identifying individuals most susceptible to risk exposures or most amenable to preventive and therapeutic interventions. This research also coincides with the emergence of unanticipated difficulties in detecting genetic variants of direct association with behavioral traits and disorders, which may be obscured if genetic effects are expressed only in predisposing environments. In this essay we consider these and other rationales for positing G×E interactions, review conceptual models meant to inform G×E interpretations from a psychological perspective, discuss points of common critique to which G×E research is vulnerable, and address the role of the environment in G×E interactions.

  18. Electroweak interactions at LEP

    CERN Document Server

    Swain, J D

    2000-01-01

    The electroweak interactions are based on an extension of the electromagnetic (Maxwell) interactions, realized in a rather odd way so that the symmetries of the theory are not immediately obvious. This "broken" theory has been the subject of intense investigation at LEP, and has passed all tests with flying colours. These lectures are meant to complement the many excellent presentations of the standard SU(2)/sub L/*U(1)/sub Y/ electroweak interactions in three main ways: first to clarify the physical meaning of symmetries in particle physics, second, to summarize the recent tests of the standard model using LEP data, and finally to look at possible roles of gravity in understanding mass. (10 refs).

  19. Neutrino interactions with nuclei

    CERN Document Server

    Leitner, T; Mosel, U; Alvarez-Ruso, L

    2008-01-01

    Current long baseline experiments aim at measuring neutrino oscillation parameters with a high precision. A critical quantity is the neutrino energy which can not be measured directly but has to be reconstructed from the observed hadrons. A good knowledge of neutrino-nucleus interactions is thus necessary to minimize the systematic uncertainties in neutrino fluxes, backgrounds and detector responses. In particular final-state interactions inside the target nucleus modify considerably the particle yields through rescattering, charge-exchange and absorption. Nuclear effects can be described with our coupled channel GiBUU transport model where the neutrino first interacts with a bound nucleon producing secondary particles which are then transported out of the nucleus. In this contribution, we give some examples for the application of our model focusing in particular on the MiniBooNE and K2K experiments.

  20. Interactive Topology Optimization

    DEFF Research Database (Denmark)

    Nobel-Jørgensen, Morten

    Interactivity is the continuous interaction between the user and the application to solve a task. Topology optimization is the optimization of structures in order to improve stiffness or other objectives. The goal of the thesis is to explore how topology optimization can be used in applications...... in an interactive and intuitive way. By creating such applications with an intuitive and simple user interface we allow non-engineers like designers and architects to easily experiment with boundary conditions, design domains and other optimization settings. This is in contrast to commercial topology optimization...... software where the users are assumed to be well-educated both in the finite element method and topology optimization. This dissertation describes how various topology optimization methods have been used for creating cross-platform applications with high performance. The user interface design is based...

  1. Interactive Information Retrieval

    DEFF Research Database (Denmark)

    Borlund, Pia

    2013-01-01

    The paper introduces the research area of interactive information retrieval (IIR) from a historical point of view. Further, the focus here is on evaluation, because much research in IR deals with IR evaluation methodology due to the core research interest in IR performance, system interaction...... and satisfaction with retrieved information. In order to position IIR evaluation, the Cranfield model and the series of tests that led to the Cranfield model are outlined. Three iconic user-oriented studies and projects that all have contributed to how IIR is perceived and understood today are presented......: The MEDLARS test, the Book House fiction retrieval system, and the OKAPI project. On this basis the call for alternative IIR evaluation approaches motivated by the three revolutions (the cognitive, the relevance, and the interactive revolutions) put forward by Robertson & Hancock-Beaulieu (1992) is presented...

  2. Dike/Drift Interactions

    Energy Technology Data Exchange (ETDEWEB)

    E. Gaffiney

    2004-11-23

    This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1).

  3. Acting, interacting, enacting

    DEFF Research Database (Denmark)

    Hazel, Spencer

    2015-01-01

    This study followed the rehearsals of a 2014 Copenhagen theatre production of Margaret Edson’s play WIT. The play depicts the palliative care provision of a woman diagnosed with advanced ovarian cancer, with an important theme of the narrative centering around the dehumanizing practices that result...... from professional medical treatment of the body, rather than of the person. I adopt an interaction analytic approach to investigate how theatre practitioners develop representations of interaction in clinical environments. The article introduces one practice from the theatre rehearsal setting – doing...

  4. Generalized interaction in multigravity

    CERN Document Server

    Duplij, Steven

    2013-01-01

    A general approach to description of multigravity models in D-dimensional space-time is presented. Different possibilities of generalization of the invariant volume are given. Then a most general form of the interaction potential is constructed, which for bigravity coincides with the Pauli-Fierz model. A thorough analysis of the model along the 3+1 expansion formalism is done. It is shown that the absence of ghosts the considered bigravity model is equivalent in the weak field limit to the massive gravity (the Pauli-Fierz model). Thus, on the concrete example it is shown, that the interaction between metrics leads to nonvanishing mass of graviton.

  5. Urban Interaction Design

    DEFF Research Database (Denmark)

    Brynskov, Martin; Bermúdez, Juan Carlos Carvajal; Fernández, Manu;

    This book is an effort to explore the newly emerging field of urban interaction design that addresses these issues. In the first part of the book, 'Foundations', we look into its origins. Where do its practitioners come from? How are they working together? What methodologies do they bring...... to the table? What are the key concepts they are addressing in their work? In the second part of the book named 'Trends', we go into current developments in the networked city and how urban interaction design as a field addresses these. Taken together, these sections will not give the definite definition...

  6. Interactive Shape Design

    CERN Document Server

    Cani, Marie-Paule; Wyvill, Geoff

    2008-01-01

    Providing an intuitive modeling system, which would enable us to communicate about any free-form shape we have in mind at least as quickly as with real-world tools, is one of the main challenges of digital shape design. The user should ideally be able to create, deform, and progressively add details to a shape, without being aware of the underlying mathematical representation nor being tied by any constraint on the geometrical or topological nature of the model. This book presents the field of interactive shape design from this perspective. Since interactively creating a shape builds on the hu

  7. Empowered interaction through creativity

    DEFF Research Database (Denmark)

    Hasselblad, Stefan; Petersson, Eva; Brooks, Tony

    2007-01-01

    This paper reflects upon a case study where exploration, play and empowerment in interactive therapy sessions with audio and visual stimuli resulted in achievement, self-esteem and a shared pride between a young adult with profound and multiple learning disabilities (PMLD), his mother and the spe......This paper reflects upon a case study where exploration, play and empowerment in interactive therapy sessions with audio and visual stimuli resulted in achievement, self-esteem and a shared pride between a young adult with profound and multiple learning disabilities (PMLD), his mother...

  8. Interacting binary stars

    CERN Document Server

    Sahade, Jorge; Ter Haar, D

    1978-01-01

    Interacting Binary Stars deals with the development, ideas, and problems in the study of interacting binary stars. The book consolidates the information that is scattered over many publications and papers and gives an account of important discoveries with relevant historical background. Chapters are devoted to the presentation and discussion of the different facets of the field, such as historical account of the development in the field of study of binary stars; the Roche equipotential surfaces; methods and techniques in space astronomy; and enumeration of binary star systems that are studied

  9. Thoughts on Interaction Design

    CERN Document Server

    Kolko, Jon

    2009-01-01

    Interaction Designers-whether practicing as Usability Engineers, Visual Interface Designers, or Information Architects-attempt to understand and shape human behavior in order to design products that are at once usable, useful, and desirable. Although the value of design is now recognized as essential to product development, the field is often misunderstood by managers and other team members, who don't understand a designer's role in a team. This can cause inefficient and ineffective products. Thoughts on Interaction Design gives individuals engaged in this profession the dialogue to justify t

  10. Virtual Interactive Space (VIS)

    DEFF Research Database (Denmark)

    Brooks, Anthony Lewis

    2015-01-01

    This paper shares code that enables the making of a Virtual Interactive Space (VIS) where the skin of the invisible active sensor area is dynamically responsive to the velocity of a limb e.g. hand. Used in proprioception training of movement the patch is at the core of the author’s Reafferentation...

  11. Exploring governmentality as interaction

    DEFF Research Database (Denmark)

    Fahnøe, Kristian

    2010-01-01

    Based on my ongoing work in relation my PhD thesis this paper examines how the Foucauldian concept of governmentality as social control can be understood as interaction among individuals in institutional settings. In theoretical terms the paper examines how governmentality can be conceptualized f...

  12. [Fluoroquinolones. Drug interactions].

    Science.gov (United States)

    Rusu, G; Dănilă, G

    2000-01-01

    This review summarizes clinically relevant drug-drug interactions for fluoroquinolones: antiacids containing aluminum and magnesium salts, iron or zinc preparations, sucralfate, cimetidine, ranitidine, warfarina, cyclosporin, rifampin, oral contraceptive steroids, benzodiazepine, probenecid, beta-lactam antibiotics, nonsteroidal anti-inflammatory drugs, metronidazole, theophylline, caffeine.

  13. CONCEPT OF DRUG INTERACTION

    Directory of Open Access Journals (Sweden)

    Singh Nidhi

    2012-07-01

    Full Text Available Drug interaction is an increasingly important cause of adverse reactions (ADR, and is the modification of the effect of one drug (object by the prior or concomitant administration of another drug (precipitant drug. Drug interaction may either enhance or diminish the intended effect of one or both drugs. For example severe haemorrhage may occur if warfarin and salicylates (asprin are combined. Precipitant drugs modify the object drug's absorption, distribution, metabolism, excretion or actual clinical effect. Nonsteroidal anti-inflammatory drugs, antibiotics and, in particular, rifampin are common precipitant drugs prescribed in primary care practice. Drugs with a narrow therapeutic range or low therapeutic index are more likely to be the objects for serious drug interactions. Object drugs in common use include warfarin, fluoroquinolones, antiepileptic drugs, oral contraceptives, cisapride and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Many other drugs, act as precipitants or objects, and a number of drugs act as both. The aim of present review is to throw light on the concept of drug interaction.

  14. Highly interactive distributed visualization

    NARCIS (Netherlands)

    Scarpa, M.; Belleman, R.G.; Sloot, P.M.A.; de Laat, C.T.A.M.

    2006-01-01

    We report on our iGrid2005 demonstration, called the "Dead Cat Demo"; an example of a highly interactive augmented reality application consisting of software services distributed over a wide-area, high-speed network. We describe our design decisions, analyse the implications of the design on applica

  15. Experiencing affective interactive art

    NARCIS (Netherlands)

    Bialoskorski, Leticia S.S.; Westerink, Joyce H.D.M.; Broek, van den Egon L.

    2010-01-01

    The progress in the field of affective computing enables the realization of affective art. This paper describes the affective interactive art system Mood Swings, which interprets and visualizes affect expressed by a person. Mood Swings is founded on the integration of a framework for affective move

  16. Socially aware interactive playgrounds

    NARCIS (Netherlands)

    Moreno, Alejandro; Delden, van Robby; Poppe, Ronald; Reidsma, Dennis

    2013-01-01

    Interactive playgrounds are technology-enhanced installations that aim to provide rich game experiences for children by combining the benefits of traditional playgrounds with those of digital games. These game experiences could be attained by addressing three design considerations: context-awareness

  17. Multiactivity in Social Interaction

    DEFF Research Database (Denmark)

    Day, Dennis; Wagner, Johannes

    2014-01-01

    Doing more than one thing at the same time – a phenomenon that is often called ‘multitasking’ – is characteristic to many situations in everyday and professional life. Although we all experience it, its real time features remain understudied. Multiactivity in Social Interaction: Beyond multitasking...

  18. Electromagnetic interaction of metamaterials

    Science.gov (United States)

    Canales, Peter R.

    The observation of extraordinary transmission through subwavelength apertures has propelled a great interest in understanding its nature. It defies classical theories of electromagnetic interaction by demanding a closer examination of the surface properties. Traditionally, as surface features become much smaller in size than a single wavelength of interest, the structure is essentially continuous. Any periodic subwavelength corrugation or aperture array should not interact strongly with an incident field and therefore not contribute to any significant transmission through the film. We find that this is not always the case and that we may tune the surface geometry at these scales to affect the overall medium behavior. It is possible that a material may transcend its own natural properties and, in essence, become a metamaterial. The following analysis examines the concepts of metamaterials from a fundamental viewpoint. It does not seek to disrupt classical theories but instead demonstrates their validity to describe a new phenomenon. Several theories have been proposed that offer unique surface interactions as evidence of enhanced transmission. It is proposed that a fundamental Maxwell representation is sufficient in predicting the interaction of an electromagnetic wave with a metamaterial. In particular, a formalism has been developed to analyze enhanced transmission through a metallic grating structure. To experimentally validate this model, a fabrication procedure has been developed that allows for the production of quality thick film structures with subwavelength features. Finally, the analysis of metamaterials looks towards the RF spectrum to demonstrate a novel design to achieve conformal waveguides and antennas.

  19. Dimensions of Group Interaction

    Science.gov (United States)

    Dawidowicz, Paula

    2008-01-01

    The correlation between positive and negative group interactions and one or another of individuals' attitudes or characteristics--moral development, critical thinking, resilience, and self efficacy--has been examined previously. However, no systemic examination of individuals' development of patterns of these characteristics and those patterns'…

  20. Interactive Foresight Simulation

    DEFF Research Database (Denmark)

    Hansen, Mette Sanne; Rasmussen, Lauge Baungaard; Jacobsen, Peter

    2016-01-01

    The Combined Simulation Approach (CSA) is a way to evaluate risks and address potential unforeseen problems in a more interactive way than what is often observed in practice in companies or sectors. The approach is based on a combination of scenario analysis and discrete-event computer simulation...

  1. Interactive Playgrounds for Children

    NARCIS (Netherlands)

    Poppe, Ronald; Delden, van Robby; Moreno, Alejandro; Reidsma, Dennis; Nijholt, Anton

    2014-01-01

    Play is an important factor in the life of children. It plays a role in their cognitive, social, and physical development, and provides entertaining and fulfilling activities in itself. As with any field of human endeavor, interactive technology has a huge potential for transforming and enhancing pl

  2. Aesthetics of Mundane Interactions

    NARCIS (Netherlands)

    Vyas, D.M.; Hassenzahl, M.

    2008-01-01

    John Dewey’s pragmatist aesthetics is used as a conceptual basis for designing new technologies that support staff-members’ mundane social interactions in an academic department. From this perspective, aesthetics is seen as a broader phenomenon that encompasses experiential aspects of staff-members’

  3. Interactive Architecture #1

    NARCIS (Netherlands)

    Oosterhuis, K.; Xia, X.

    2007-01-01

    The iA bookzine series will consist of twelve issues, bi-annually published over a period of six years under the supervision of Prof. ir. Kas Oosterhuis, director of the Hperbody at the Delft University of Technology. Interactive Architecture - from here on abbreviated as iA - is NOT simply archite

  4. Alkane dimers interaction

    DEFF Research Database (Denmark)

    Ferrighi, Lara; Madsen, Georg Kent Hellerup; Hammer, Bjørk

    2010-01-01

    The interaction energies of a series of n-alkane dimers, from methane to decane, have been investigated with Density Functional Theory (DFT), using the MGGA-M06-L density functional. The results are compared both to the available wavefunction-based values as well as to dispersion corrected DFT...

  5. TIDE-TSUNAMI INTERACTIONS

    Directory of Open Access Journals (Sweden)

    Zygmunt Kowalik

    2006-01-01

    Full Text Available In this paper we investigate important dynamics defining tsunami enhancement in the coastal regions and related to interaction with tides. Observations and computations of the Indian Ocean Tsunami usually show amplifications of the tsunami in the near-shore regions due to water shoaling. Additionally, numerous observations depicted quite long ringing of tsunami oscillations in the coastal regions, suggesting either local resonance or the local trapping of the tsunami energy. In the real ocean, the short-period tsunami wave rides on the longer-period tides. The question is whether these two waves can be superposed linearly for the purpose of determining the resulting sea surface height (SSH or rather in the shallow water they interact nonlinearly, enhancing/reducing the total sea level and currents. Since the near–shore bathymetry is important for the run-up computation, Weisz and Winter (2005 demonstrated that the changes of depth caused by tides should not be neglected in tsunami run-up considerations. On the other hand, we hypothesize that much more significant effect of the tsunami-tide interaction should be observed through the tidal and tsunami currents. In order to test this hypothesis we apply a simple set of 1-D equations of motion and continuity to demonstrate the dynamics of tsunami and tide interaction in the vicinity of the shelf break for two coastal domains: shallow waters of an elongated inlet and narrow shelf typical for deep waters of the Gulf of Alaska.

  6. Connectionist Interaction Information Retrieval.

    Science.gov (United States)

    Dominich, Sandor

    2003-01-01

    Discussion of connectionist views for adaptive clustering in information retrieval focuses on a connectionist clustering technique and activation spreading-based information retrieval model using the interaction information retrieval method. Presents theoretical as well as simulation results as regards computational complexity and includes…

  7. Unparticle self-interactions

    Science.gov (United States)

    Georgi, Howard; Kats, Yevgeny

    2010-02-01

    We develop techniques for studying the effects of self-interactions in the conformal sector of an unparticle model. Their physics is encoded in the higher n-point functions of the conformal theory. We study inclusive processes and argue that the inclusive production of unparticle stuff in standard model processes due to the unparticle self-interactions can be decomposed using the conformal partial wave expansion and its generalizations into a sum over contributions from the production of various kinds of unparticle stuff, corresponding to different primary conformal operators. Such processes typically involve the production of unparticle stuff associated with operators other than those to which the standard model couples directly. Thus just as interactions between particles allow scattering processes to produce new particles in the final state, so unparticle self-interactions cause the production of various kinds of unparticle stuff. We discuss both inclusive and exclusive methods for computing these processes. The resulting picture, we believe, is a step towards understanding what unparticle stuff “looks like” because it is quite analogous to way we describe the production and scattering of ordinary particles in quantum field theory, with the primary conformal operators playing the role of particles and the coefficients in the conformal partial wave expansion (and its generalization to include more fields) playing the role of amplitudes. We exemplify our methods in the 2D toy model that we discussed previously in which the Banks-Zaks theory is exactly solvable.

  8. Fibronectin-cell interactions

    DEFF Research Database (Denmark)

    Couchman, J R; Austria, M R; Woods, A

    1990-01-01

    Fibronectins are widespread extracellular matrix and body fluid glycoproteins, capable of multiple interactions with cell surfaces and other matrix components. Their structure at a molecular level has been resolved, yet there are still many unanswered questions regarding their biologic activity i...

  9. Interactive Tabletops in Education

    Science.gov (United States)

    Dillenbourg, Pierre; Evans, Michael

    2011-01-01

    Interactive tabletops are gaining increased attention from CSCL researchers. This paper analyses the relation between this technology and teaching and learning processes. At a global level, one could argue that tabletops convey a socio-constructivist flavor: they support small teams that solve problems by exploring multiple solutions. The…

  10. Interactive Digital Signal Processor

    Science.gov (United States)

    Mish, W. H.

    1985-01-01

    Interactive Digital Signal Processor, IDSP, consists of set of time series analysis "operators" based on various algorithms commonly used for digital signal analysis. Processing of digital signal time series to extract information usually achieved by applications of number of fairly standard operations. IDSP excellent teaching tool for demonstrating application for time series operators to artificially generated signals.

  11. Gaze interaction from bed

    DEFF Research Database (Denmark)

    Hansen, John Paulin; San Agustin, Javier; Jensen, Henrik Tomra Skovsgaard Hegner

    2011-01-01

    This paper presents a low-cost gaze tracking solution for bedbound people composed of free-ware tracking software and commodity hardware. Gaze interaction is done on a large wall-projected image, visible to all people present in the room. The hardware equipment leaves physical space free to assist...

  12. Protein-protein interactions

    DEFF Research Database (Denmark)

    Byron, Olwyn; Vestergaard, Bente

    2015-01-01

    Responsive formation of protein:protein interaction (PPI) upon diverse stimuli is a fundament of cellular function. As a consequence, PPIs are complex, adaptive entities, and exist in structurally heterogeneous interplays defined by the energetic states of the free and complexed protomers......, are reported. The aim is to depict how the elucidation of the interplay of structures requires the interplay of methods....

  13. Interactive Purchasing Situations

    NARCIS (Netherlands)

    Groote Schaarsberg, M.; Borm, P.E.M.; Hamers, H.J.M.; Reijnierse, J.H.

    2012-01-01

    Abstract: This paper introduces a new class of interactive cooperative purchasing situations and provides an explicit alternative characterization of the nucleolus of cooperative games, which offers an alternative to Kohlberg (1971). In our cooperative purchasing situation, the unit price of a commo

  14. Electronically Enhanced Classroom Interaction.

    Science.gov (United States)

    Draper, Stephen; Cargill, Julie; Cutts, Quintin

    A design rationale for introducing electronic equipment (a group response system) for student interaction in lecture theaters is presented, linking the instructional design to theory. The effectiveness of the equipment for learning depends mostly on what pedagogic method is employed. Various alternative types are introduced, including: assessment;…

  15. Interaction in Information Systems - Beyond Human-Computer Interaction

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    The purpose of this paper is to discuss and analyze the role of interaction in information systems. Interaction represents dynamic relations between actors and other elements in information systems. We introduce a semi-formal notation that we use to describe a set of interaction patterns and we...... illustrate how the notation can be used to describe mediated interaction. We use the interaction patterns to evaluate a set of modeling languages. No single language supports all relevant aspects of interaction modeling. We use the interaction patterns to identify to general and supplementary forms...... of interaction-interaction based on exchange of objects and interaction based on exchange of commands. None of the modeling languages that we analyze support both forms in a rich way....

  16. Interaction Design for Public Spaces

    DEFF Research Database (Denmark)

    Kortbek, Karen Johanne

    2008-01-01

    In this abstract I describe the doctorial research project "Interaction Design for Public Spaces". The objective of the project is to explore and design interaction contexts in culture related public spaces such as museums, experience centres and festivals. As a perspective on this domain, I...... will help interaction designers when designing for bodily movement, and communicating and staging interactive content in public spaces....

  17. 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.

  18. Interactive Parallel and Distributed Processing

    DEFF Research Database (Denmark)

    Lund, Henrik Hautop; Pagliarini, Luigi

    2010-01-01

    We present the concept of interactive parallel and distributed processing, and the challenges that programmers face in designing interactive parallel and distributed systems. Specifically, we introduce the challenges that are met and the decisions that need to be taken with respect...... to distributedness, master dependency, software behavioural models, adaptive interactivity, feedback, connectivity, topology, island modeling, and user interaction. We introduce the system of modular interactive tiles as a tool for easy, fast, and flexible exploration of these issues, and through examples show how...... to implement interactive parallel and distributed processing with different software behavioural models such as open loop, randomness based, rule based, user interaction based, AI and ALife based software....

  19. Student interaction in workshops

    DEFF Research Database (Denmark)

    Evers, Winie

    2014-01-01

    A kind of teaching for active learning has been experimented with at SDU Sønderborg as part of the course Supply Chain Dynamics. In this course the students learn about complex systems, system dynamics as well as supply chain instability and oscillation, the course lecturer invited the author...... to experiment with novel workshop methods and techniques, where objects are used to illustrate and model business issues (Heinemann et al, 2011, Buur et al, 2013). The idea was to see how students could be engaged in a different and more interactive way to learn about these topics, by assigning the students...... teaching should reflect this diversity by embracing and experimenting with multiple forms, including activation of students by students’ interaction and manipulation with objects....

  20. Interacting Galaxies with MOND

    CERN Document Server

    Tiret, O

    2007-01-01

    We compare N-body simulations performed in MOND with analogs in Newtonian gravity with dark matter (DM). We have developed a code which solves the Poisson equation in both gravity models. It is a grid solver using adaptive mesh refinement techniques, allowing us to study isolated galaxies as well as interacting galaxies. Galaxies in MOND are found to form bars faster and stronger than in the DM model. In Newton dynamics, it is difficult to reproduce the observed high frequency of strong bars, while MOND appears to fit better the observations. Galaxy interactions and mergers, such as the Antennae, are also simulated with Newton and MOND dynamics. In the latter, dynamical friction is much weaker, and merging time-scales are longer. The formation of tidal dwarf galaxies in tidal tails are also compared in MOND and Newton+DM models.

  1. Neutrinophilic nonstandard interactions

    Science.gov (United States)

    Farzan, Yasaman; Heeck, Julian

    2016-09-01

    We construct UV-complete models for nonstandard neutrino interactions mediated by a sub-GeV gauge boson Z' coupled to baryon number B or B -L . A flavor-dependent Z' coupling to neutrinos is induced by mixing a U (1 )'-charged Dirac fermion with the active neutrinos, naturally suppressing flavor violation or nonuniversality of the charged leptons to the loop level. We show that these models can give rise to large flavor-conserving as well as flavor-violating nonstandard neutral-current neutrino interactions potentially observable in current or future oscillation experiments such as DUNE without being in conflict with other constraints such as neutrino scattering or lepton-flavor-violating decays. In particular, the LMA-Dark solution to the solar-neutrino anomaly can be obtained for U (1 )B, but not for U (1 )B-L.

  2. Multiparton Interactions and Rescattering

    CERN Document Server

    Corke, Richard

    2009-01-01

    The concept of multiple partonic interactions in hadronic events is vital for the understanding of both minimum-bias and underlying-event physics. The area is rather little studied, however, and current models offer a far from complete coverage, even of the effects we know ought to be there. In this article we address one such topic, namely that of rescattering, where an already scattered parton is allowed to take part in another subsequent scattering. A framework for rescattering is introduced for the Pythia 8 event generator and fully integrated with normal multiparton interactions and initial- and final-state radiation. Using this model, the effects on event structure are studied, and distributions are shown both for minimum-bias and jet events.

  3. Interactive White Board

    Directory of Open Access Journals (Sweden)

    Asadullah Khan Praveen Kumar Arun Nair Rishi R Hegde

    2012-02-01

    Full Text Available Visual Screen uses an inexpensive technique to transform an ordinary screen into a touch screen[1] using an ordinary camera[2]. The system can fullfill many tasks such as controlling a remote large display, and simulating a physical keyboard[4]. Users can naturally use their fingers or other tip pointers to issue commands and type texts. In many intelligent environments, instead of using conventional mice[3], keyboards[4] and joysticks[5], people are looking for an intuitive, immersive and cost-efficient interaction device. We describe two vision-based interface systems[10]. The first, Visual Screen, uses an inexpensive technique to transform an ordinary screen into a touch screen[1] using an ordinary camera[2], and a user can use his/her finger to interact with the computer. Touch screens[1] are very convenient because one can directly point to where it is interesting. No conventional mice[3] are needed.

  4. Interactional Expertise and Embodiment

    CERN Document Server

    Collins, Harry

    2016-01-01

    In Part 1 of this paper, I introduce the idea of interactional expertise while in Part 2, I focus on its implications for philosophical theories of the importance of the body in forming our conceptual world. I argue that the way philosophers have dealt with the body turns attention away from the most important questions and that we cannot answer these questions without making the notion of socialisation, and therefore interactional expertise, a central concept in our thinking. This makes language at least as important, and often more important than bodily practice in our understanding of the world. The notion of a disembodied socialised agent leads in the direction of interesting questions while the notion of an embodied but unsocialised human actor is unimaginable.

  5. Dynamics of interacting diseases

    CERN Document Server

    Sanz, Joaquín; Meloni, Sandro; Moreno, Yamir

    2014-01-01

    Current modeling of infectious diseases allows for the study of complex and realistic scenarios that go from the population to the individual level of description. Most epidemic models however assume that the spreading process takes place on a single level (be it a single population, a meta-population system or a network of contacts). The latter is in part a consequence of our still limited knowledge about the interdependency of the many mechanisms and factors involved in disease spreading. In particular, interdependent contagion phenomena can only be addressed if we go beyond the scheme one pathogen-one network. In this paper, we study a model that allows describing the spreading dynamics of two concurrent diseases and apply it to a paradigmatic case of disease-disease interaction: the interaction between AIDS and Tuberculosis. Specifically, we characterize analytically the epidemic thresholds of the two diseases for different scenarios and also compute the temporal evolution characterizing the unfolding dyn...

  6. Intelligent Interactive Multimedia

    CERN Document Server

    Watanabe, Toyohide; Takahashi, Naohisa; 5th International Conference on Intelligent Interactive Multimedia Systems and Services

    2012-01-01

    This volume contains the Proceedings of the 5th International Conference on Intelligent Interactive Multimedia Systems and Services (KES-IIMSS-12).  The Conference was jointly organised by Nagoya University in Japan and the KES International organisation, and held in the attractive city of Gifu.   The KES-IIMSS conference series, (series chairs Prof. Maria Virvou and Prof. George Tsihrintzis), presents novel research in various areas of intelligent multimedia system relevant to the development of a new generation of interactive, user-centric devices and systems.  The aim of the conference is to provide an internationally respected forum for scientific research in the technologies and applications of this new and dynamic research area.

  7. Theory of gravitational interactions

    CERN Document Server

    Gasperini, Maurizio

    2017-01-01

    This is the second edition of a well-received book that is a modern, self-contained introduction to the theory of gravitational interactions. The new edition includes more details on gravitational waves of cosmological origin, the so-called brane world scenario, and gravitational time-delay effects. The first part of the book follows the traditional presentation of general relativity as a geometric theory of the macroscopic gravitational field, while the second, more advanced part discusses the deep analogies (and differences) between a geometric theory of gravity and the “gauge” theories of the other fundamental interactions. This fills a gap within the traditional approach to general relativity which usually leaves students puzzled about the role of gravity. The required notions of differential geometry are reduced to the minimum, allowing room for aspects of gravitational physics of current phenomenological and theoretical interest, such as the properties of gravitational waves, the gravitational inter...

  8. Interactive protein manipulation

    Energy Technology Data Exchange (ETDEWEB)

    SNCrivelli@lbl.gov

    2003-07-01

    We describe an interactive visualization and modeling program for the creation of protein structures ''from scratch''. The input to our program is an amino acid sequence -decoded from a gene- and a sequence of predicted secondary structure types for each amino acid-provided by external structure prediction programs. Our program can be used in the set-up phase of a protein structure prediction process; the structures created with it serve as input for a subsequent global internal energy minimization, or another method of protein structure prediction. Our program supports basic visualization methods for protein structures, interactive manipulation based on inverse kinematics, and visualization guides to aid a user in creating ''good'' initial structures.

  9. Ultrahigh energy neutrino interactions

    Science.gov (United States)

    Domokos, G.; Elliot, B.; Kovesi-Domokos, S.; Mrenna, S.

    1990-03-01

    Ultrahigh energy neutrinos are valuable probes of physics beyond the Standard Model. Neutrinos of the highest energies are emitted by point sources in the sky. We review briefly the predictions of the Standard Model concerning neutrino interactions. We further argue that a number of preon models designed to overcome some difficulties of the Standard Model leads to a blurring of the distinction between leptons and quarks. As a consequence, at sufficiently high energies neutrinos acquire ``anomalous'' interactions. While this phenomenon can probably explain the observed muon excess in extensive air showers (EAS), it can be also tested by studying the absorption of the primaries on the cosmic microwave background. We discuss some observations to be performed in the search of such ``new physics'' beyond the Standard Model.

  10. Interactive Information Retrieval:

    DEFF Research Database (Denmark)

    Borlund, Pia

    This presentation addresses methodological issues of interactive information retrieval (IIR) evaluation in terms of what it entails to study users' use and interaction with IR systems, as well as their satisfaction with retrieved information. In particular, the presentation focuses on test design......, and it takes a look into the toolbox of IIR test design with reference to data collection methods and test procedure. It calls for careful and well-planned studies to qualify the knowledgebase generated as a result of the conducted IIR studies. The presentation further reflects on the need for an updated...... IIR from the perspective of search dedication and task load in order to also include everyday life information seeking? With this presentation, the IIR community is invited to an exchange of ideas and is encouraged to engage in collaborations with the solving of these (and other) issues to our joint...

  11. Ligand-Receptor Interactions

    CERN Document Server

    Bongrand, Pierre

    2008-01-01

    The formation and dissociation of specific noncovalent interactions between a variety of macromolecules play a crucial role in the function of biological systems. During the last few years, three main lines of research led to a dramatic improvement of our understanding of these important phenomena. First, combination of genetic engineering and X ray cristallography made available a simultaneous knowledg of the precise structure and affinity of series or related ligand-receptor systems differing by a few well-defined atoms. Second, improvement of computer power and simulation techniques allowed extended exploration of the interaction of realistic macromolecules. Third, simultaneous development of a variety of techniques based on atomic force microscopy, hydrodynamic flow, biomembrane probes, optical tweezers, magnetic fields or flexible transducers yielded direct experimental information of the behavior of single ligand receptor bonds. At the same time, investigation of well defined cellular models raised the ...

  12. Interactive Chemical Reactivity Exploration

    CERN Document Server

    Haag, Moritz P; Bosson, Mael; Redon, Stephane; Reiher, Markus

    2014-01-01

    Elucidating chemical reactivity in complex molecular assemblies of a few hundred atoms is, despite the remarkable progress in quantum chemistry, still a major challenge. Black-box search methods to find intermediates and transition-state structures might fail in such situations because of the high-dimensionality of the potential energy surface. Here, we propose the concept of interactive chemical reactivity exploration to effectively introduce the chemist's intuition into the search process. We employ a haptic pointer device with force-feedback to allow the operator the direct manipulation of structures in three dimensions along with simultaneous perception of the quantum mechanical response upon structure modification as forces. We elaborate on the details of how such an interactive exploration should proceed and which technical difficulties need to be overcome. All reactivity-exploration concepts developed for this purpose have been implemented in the Samson programming environment.

  13. Interactions faibles en harmonie

    CERN Multimedia

    1978-01-01

    Des résultats de haute précision obtenus à Stanford ouvrent la voie vers une unification des interactions faible et électromagnétique ; Présentation à la Conférence neutrino d'Oxford de nouveaux résultats en accord avec la théorie de la synthèse des forces faible et électro- magnétique

  14. ELEMENTARY PARTICLE INTERACTIONS

    Energy Technology Data Exchange (ETDEWEB)

    EFREMENKO, YURI; HANDLER, THOMAS; KAMYSHKOV, YURI; SIOPSIS, GEORGE; SPANIER, STEFAN

    2013-07-30

    The High-Energy Elementary Particle Interactions group at UT during the last three years worked on the following directions and projects: Collider-based Particle Physics; Neutrino Physics, particularly participation in “NOνA”, “Double Chooz”, and “KamLAND” neutrino experiments; and Theory, including Scattering amplitudes, Quark-gluon plasma; Holographic cosmology; Holographic superconductors; Charge density waves; Striped superconductors; and Holographic FFLO states.

  15. Scoping Agriculture, Wetland Interactions

    OpenAIRE

    2015-01-01

    Agriculture is identified as the main cause of wetland degradation and loss. Using a drivers, pressures, state changes, impacts and responses (DPSIR) framework to analyze 90 cases drawn from all parts of the world and all wetland types, this report assesses the character of agriculture - wetlands interactions (AWIs) and their impacts in socio-economic and ecosystem services terms. The report is a technical framework that is used to scope out the relevance and nature of AWIs, identify response...

  16. Pharmacokinetic interactions with thiazolidinediones.

    Science.gov (United States)

    Scheen, André J

    2007-01-01

    Type 2 diabetes mellitus is a complex disease combining defects in insulin secretion and insulin action. New compounds called thiazolidinediones or glitazones have been developed for reducing insulin resistance. After the withdrawal of troglitazone because of liver toxicity, two compounds are currently used in clinical practice, rosiglitazone and pioglitazone. These compounds are generally used in combination with other pharmacological agents. Because they are metabolised via cytochrome P450 (CYP), glitazones are exposed to numerous pharmacokinetic interactions. CYP2C8 and CYP3A4 are the main isoenzymes catalysing biotransformation of pioglitazone (as with troglitazone), whereas rosiglitazone is metabolised by CYP2C9 and CYP2C8. For both rosiglitazone and pioglitazone, the most relevant interactions have been described in healthy volunteers with rifampicin (rifampin), which results in a significant decrease of area under the plasma concentration-time curve [AUC] (54-65% for rosiglitazone, p<0.001; 54% for pioglitazone, p<0.001), and with gemfibrozil, which results in a significant increase of AUC (130% for rosiglitazone, p<0.001; 220-240% for pioglitazone, p<0.001). The relevance of such drug-drug interactions in patients with type 2 diabetes remains to be evaluated. However, in the absence of clinical data, it is prudent to reduce the dosage of each glitazone by half in patients treated with gemfibrozil. Conversely, rosiglitazone and pioglitazone do not seem to significantly affect the pharmacokinetics of other compounds. Although some food components have also been shown to potentially interfere with drugs metabolised with the CYP system, no published study deals specifically with these possible CYP-mediated food-drug interactions with glitazones.

  17. Orbital interactions in chemistry

    CERN Document Server

    Albright, Thomas A; Whangbo, Myung-Hwan

    2013-01-01

    Explains the underlying structure that unites all disciplines in chemistry Now in its second edition, this book explores organic, organometallic, inorganic, solid state, and materials chemistry, demonstrating how common molecular orbital situations arise throughout the whole chemical spectrum. The authors explore the relationships that enable readers to grasp the theory that underlies and connects traditional fields of study within chemistry, thereby providing a conceptual framework with which to think about chemical structure and reactivity problems. Orbital Interactions

  18. Designing for interaction

    OpenAIRE

    2004-01-01

    At present, the design of computer-supported group-based learning (CS)GBL) is often based on subjective decisions regarding tasks, pedagogy and technology, or concepts such as ‘cooperative learning’ and ‘collaborative learning’. Critical review reveals these concepts as insufficiently substantial to serve as a basis for (CS)GBL design. Furthermore, the relationship between outcome and group interaction is rarely specified a priori. Thus, there is a need for a more systematic approach to desig...

  19. Neutrino Interactions with Nuclei

    CERN Document Server

    Leitner, T; Mosel, U; Alvarez-Ruso, L

    2007-01-01

    We investigate neutrino-nucleus collisions at intermediate energies incorporating quasi-elastic scattering and the excitation of 13 resonances as elementary processes, taking into account medium effects such as Fermi motion, Pauli blocking, mean-field potentials and in-medium spectral functions. A coupled-channel treatment of final state interactions is achieved with the GiBUU transport model. Results for inclusive reactions, neutrino- and electron-induced, as well as for pion production and nucleon knockout are presented.

  20. Interactive Mathematics Textbooks

    DEFF Research Database (Denmark)

    Sinclair, Robert

    1999-01-01

    We claim that important considerations have been overlooked in designinginteractive mathematics educational software in the past.In particular,most previous work has concentrated on how to make use ofpre-existing software in mathematics education, rather than firstasking the more...... fundamentalquestion of which requirements mathematics education puts on software, and thendesigning software to fulfil these requirements.We present a working prototype system which takes a script defining an interactivemathematicaldocument and then provides a reader with an interactive realization of thatdocument....

  1. Wave-Ice interaction

    Institute of Scientific and Technical Information of China (English)

    沈奚海莉

    2001-01-01

    The growth and movement of sea ice cover are influenced by the presence of wave field. Inturn, the wave field is influenced by the presence of ice cover. Their interaction is not fully understood.In this paper, we discuss some current understanding on wave attenuation when it propagates through frag-mented ice cover, ice drift due to the wave motion, and the growth characteristics of ice cover in wave field.

  2. Brain-gut interactions.

    OpenAIRE

    Bonaz, Bruno

    1994-01-01

    International audience; Our digestive tract has an autonomous functioning but also has a bidirectional relation with our brain known as brain-gut interactions. This communication is mediated by the autonomous nervous system, i.e., the sympathetic and parasympathetic nervous systems, with a mixed afferent and efferent component, and the circumventricular organs located outside the blood-brain barrier. The vagus nerve, known as the principal component of the parasympathetic nervous system, is a...

  3. Renormalizability and nonrenormalizable interactions

    Institute of Scientific and Technical Information of China (English)

    YAO Hai-Bo; WU Shi-Shu

    2009-01-01

    Arguments are provided which show that extension of renormalizability in quantum field theory is possible. By an appropriate choice of effective Lagrangian, a dressed Feynman propagator is obtained. In this scheme, higher order Feynman diagrams become self-convergent and nonrenormalizable interactions become renormalizable. As an example, the vacuum fluctuation effects on p meson mass for the vector-tensor coupling model is discussed. It is found that the result can agree with the experimental value when coupling constant is adjusted.

  4. Model Checking Feature Interactions

    DEFF Research Database (Denmark)

    Le Guilly, Thibaut; Olsen, Petur; Pedersen, Thomas;

    2015-01-01

    This paper presents an offline approach to analyzing feature interactions in embedded systems. The approach consists of a systematic process to gather the necessary information about system components and their models. The model is first specified in terms of predicates, before being refined to t...... to timed automata. The consistency of the model is verified at different development stages, and the correct linkage between the predicates and their semantic model is checked. The approach is illustrated on a use case from home automation....

  5. Campylobacter-Acanthamoeba interactions.

    Science.gov (United States)

    Vieira, Ana; Seddon, Alan M; Karlyshev, Andrey V

    2015-05-01

    Campylobacter jejuni is a foodborne pathogen recognized as the major cause of human bacterial enteritis. Undercooked poultry products and contaminated water are considered as the most important sources of infection. Some studies suggest transmission and survival of this bacterial pathogen may be assisted by the free-living protozoa Acanthamoeba. The latter is known to play the role of a host for various pathogenic bacteria, protecting them from harsh environmental conditions. Importantly, there is a similarity between the mechanisms of bacterial survival within amoebae and macrophages, making the former a convenient tool for the investigation of the survival of pathogenic bacteria in the environment. However, the molecular mechanisms involved in the interaction between Campylobacter and Acanthamoeba are not well understood. Whilst some studies suggest the ability of C. jejuni to survive within the protozoa, the other reports support an extracellular mode of survival only. In this review, we focus on the studies investigating the interaction between Campylobacter and Acanthamoeba, address some reasons for the contradictory results, and discuss possible implications of these results for epidemiology. Additionally, as the molecular mechanisms involved remain unknown, we also suggest possible factors that may be involved in this process. Deciphering the molecular mechanisms of pathogen-protozoa interaction will assist in a better understanding of Campylobacter lifestyle and in the development of novel antibacterial drugs.

  6. Intercultural Interaction and Handicrafts

    Directory of Open Access Journals (Sweden)

    Mine CAN

    2015-07-01

    Full Text Available Technological developments in the world since the mid - 20th century, has increased intercultural communication and the whole world today has been informed of the existence of societies even in the most remote corners of the world. With increase in globaliza tion in cultural context, the importance of local differences has emerged more today. As a result, a process has initiated in which the similarities with differences, localization with the universalization and modernization with the tradition experienced s imutaneously and intercultural interaction has become inevitable and a natural phenomenon. However, handicrafts has been affected by cultural interactions negatively and the mistakes done caused the national culture and identities to weaken. For this reaso n, the necessity of experience of changing and developing in the frame of development with identity, transformation and cultural heritage today is emphasized. To be protected from the negative effects of the global interaction, many government produce prot ection and sustenance contracts, laws and projects by engaging in various initiatives. In the study, subjects is discussed with the examples of successful countries that aim to promote their local cultures globally and provide income.

  7. Pharmacological interactions of vasoconstrictors.

    Science.gov (United States)

    Gómez-Moreno, Gerardo; Guardia, Javier; Cutando, Antonio; Calvo-Guirado, José Luis

    2009-01-01

    This article is the first of a series on pharmacological interactions involving medicaments commonly prescribed and/or used in odontology: vasoconstrictors in local anaesthetics and anti-inflammatory and anti-microbial analgesics. The necessity for the odontologist to be aware of adverse reactions as a result of the pharmacological interactions is due to the increase in medicament consumption by the general population. There is a demographic change with greater life expectancy and patients have increased chronic health problems and therefore have increased medicament intake. The presence of adrenaline (epinephrine) and other vasoconstrictors in local odontological anaesthetics is beneficial in relation to the duration and depth of anaesthesia and reduces bleeding and systemic toxicity of the local anaesthetic. However, it might produce pharmacological interactions between the injected vasoconstrictors and the local anaesthetic and adrenergic medicament administered exogenically which the odontologist should be aware of, especially because of the risk of consequent adverse reactions. Therefore the importance of conducting a detailed clinical history of the general state of health and include all medicaments, legal as well as illegal, taken by the patient.

  8. Transactional interactive multimedia banner

    Science.gov (United States)

    Shae, Zon-Yin; Wang, Xiping; von Kaenel, Juerg

    2000-05-01

    Advertising in TV broadcasting has shown that multimedia is a very effective means to present merchandise and attract shoppers. This has been applied to the Web by including animated multimedia banner ads on web pages. However, the issues of coupling interactive browsing, shopping, and secure transactions e.g. from inside a multimedia banner, have only recently started to being explored. Currently there is an explosively growing amount of back-end services available (e.g., business to business commerce (B2B), business to consumer (B2C) commerce, and infomercial services) in the Internet. These services are mostly accessible through static HTML web pages at a few specific web portals. In this paper, we will investigate the feasibility of using interactive multimedia banners as pervasive access point for the B2C, B2B, and infomercial services. We present a system architecture that involves a layer of middleware agents functioning as the bridge between the interactive multimedia banners and back-end services.

  9. Representation, interaction, and intersubjectivity.

    Science.gov (United States)

    Alterman, Richard

    2007-09-10

    What the participants share, their common "sense" of the world, creates a foundation, a framing, an orientation that enables human actors to see and act in coordination with one another. For recurrent activities, the methods the participants use to understand each other as they act change, making the intersubjective space in which actors operate richer and easier to produce. This article works through some of the issues that emerge from a close examination of intersubjectivity as it is managed through representation and interaction. The data that are presented document, in detail, a sequence of related interactions, within and across episodes of cooperation, where continuity and change can be observed. The emergence of conversational structure and coordinating representations are significant milestones in the long-term development of a representational practice that support the runtime co-construction of intersubjective space. Conversational structures emerge interactively to mediate recurrent points of coordination in the domain activity, and only secondarily the conversation itself. Coordinating representations change the representational practice of the participants by making it easier to manage their "shared view" of the collective work, enabling the participants to make progress, expand the field of the common activity, while exhibiting more control of if and when explicit grounding occurs.

  10. Web Interactive Campus Map

    Directory of Open Access Journals (Sweden)

    Marylene S. Eder

    2015-03-01

    Full Text Available Abstract Interactive campus map is a web based application that can be accessed through a web browser. With the Google Map Application Programming Interface availability of the overlay function has been taken advantage to create custom map functionalities. Collection of building points were gathered for routing and to create polygons which serves as a representation of each building. The previous campus map provides a static visual representation of the campus. It uses legends building name and its corresponding building number in providing information. Due to its limited capabilities it became a realization to the researchers to create an interactive campus map.Storing data about the building room and staff information and university events and campus guide are among the primary features that this study has to offer. Interactive Web-based Campus Information System is intended in providing a Campus Information System.It is open to constant updates user-friendly for both trained and untrained users and capable of responding to all needs of users and carrying out analyses. Based on the data gathered through questionnaires researchers analyzed the results of the test survey and proved that the system is user friendly deliver information to users and the important features that the students expect.

  11. Bacteria-surface interactions.

    Science.gov (United States)

    Tuson, Hannah H; Weibel, Douglas B

    2013-05-14

    The interaction of bacteria with surfaces has important implications in a range of areas, including bioenergy, biofouling, biofilm formation, and the infection of plants and animals. Many of the interactions of bacteria with surfaces produce changes in the expression of genes that influence cell morphology and behavior, including genes essential for motility and surface attachment. Despite the attention that these phenotypes have garnered, the bacterial systems used for sensing and responding to surfaces are still not well understood. An understanding of these mechanisms will guide the development of new classes of materials that inhibit and promote cell growth, and complement studies of the physiology of bacteria in contact with surfaces. Recent studies from a range of fields in science and engineering are poised to guide future investigations in this area. This review summarizes recent studies on bacteria-surface interactions, discusses mechanisms of surface sensing and consequences of cell attachment, provides an overview of surfaces that have been used in bacterial studies, and highlights unanswered questions in this field.

  12. On the Dark Sector Interactions

    CERN Document Server

    Cai, Rong-Gen

    2009-01-01

    The nature of dark energy (DE) is still unknown. It is possible that there exists some interaction between DE and dark matter (DM), and a suitable interaction can alleviate the coincidence problem. Several phenomenological interacting forms are proposed and are fitted with observations in the literature. In this paper we investigate the possible interaction in a way independent of specific interacting forms from observational data (SNe, BAO, CMB and Hubble parameter). We divide the whole range of redshift into four bins and set the interacting term $\\delta(z)$ to be piecewise constant in each redshift bin. We consider four parameterizations of the equation of state $w_{de}$ for DE and find that $\\delta(z)$ is likely to cross the non-interacting ($\\delta=0$) line at a recent time. It suggests that to study the interaction between DE and DM, more general phenomenological forms of the interacting term should be considered.

  13. Trapped Three Interacting Bosons with a Short-Ranged Interaction

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang

    2006-01-01

    A system of three bosons trapped by a parabolic confinement and interacting with a short-ranged interaction has been investigated by the exact diagonalization of the Hamiltonian matrix. We report a calculation for the energy spectrum of the low-lying states of a system of three interacting bosons. The important feature of the low-lying states of three interacting bosons trapped by a parabolic confinement is obtained via an analysis of the energy spectrum.

  14. Flavivirus-Mosquito Interactions

    Directory of Open Access Journals (Sweden)

    Yan-Jang S. Huang

    2014-11-01

    Full Text Available The Flavivirus genus is in the family Flaviviridae and is comprised of more than 70 viruses. These viruses have a broad geographic range, circulating on every continent except Antarctica. Mosquito-borne flaviviruses, such as yellow fever virus, dengue virus serotypes 1–4, Japanese encephalitis virus, and West Nile virus are responsible for significant human morbidity and mortality in affected regions. This review focuses on what is known about flavivirus-mosquito interactions and presents key data collected from the field and laboratory-based molecular and ultrastructural evaluations.

  15. Interacting Double Coset Magnons

    CERN Document Server

    Ali, Abdelhamid Mohamed Adam; Tahiridimbisoa, Nirina Hasina; Mahu, Augustine Larweh

    2015-01-01

    We consider the anomalous dimensions of restricted Schur polynomials constructed using n~O(N) complex adjoint scalars Z and m complex adjoint scalars Y. We fix m<interactions. The form of this new operator mixing is studied in detail for a system of two giant gravitons with four strings attached.

  16. Cultivating objects in interaction

    DEFF Research Database (Denmark)

    Hazel, Spencer

    2014-01-01

    is chapter explores patterns of repeated orientations to physical objects in interactants’ visuo-spatial and haptic surround. A number of examples are presented from advice-giving activities in various institutional settings, where participants-in-interaction initially draw on material objects...... on these associations for describing, disambiguating or clarifying aspects of the relatively complex procedural frameworks discussed in the settings. is suggests that the temporal stability of material objects available to participants makes them an ideal resource to be developed as visual motifs....

  17. [Tenofovir: pharmacology and interactions].

    Science.gov (United States)

    Azanza, José Ramón; García Quetglas, Emilio; Sádaba, Belén; Gómez-Giu, Almudena

    2008-06-01

    Tenofovir is a nucleotide analogue and consequently its mechanism of action differs from that of nucleoside analogues. This drug is administered orally in the form of disoproxil ester, which is deesterified to achieve a bioavailability of more than 20%. This bioavailability slightly increases if tenofovir is taken with a fat-rich meal. This drug has broad tissue distribution, aided by its small molecular size and very low protein binding, and is eliminated as unchanged drug in the urine through glomerular filtration and active tubular secretion. Because of this latter characteristic, dosage adjustments are required in patients with renal insufficiency. The intracellular half-life of tenofovir is more than 10 times greater than the plasma half-life. Because of the pharmacokinetic profile of tenofovir, interactions with other drugs are scarce. Within the class of antiretroviral agents, an increase in the bioavailability of didanosine has been described, leading to the recommendation that the dose of didanosine be reduced when used in combination with tenofovir. Tenofovir can be used without adjustments with other nucleoside and nonnucleoside reverse transcriptase inhibitors. Equally, tenofovir seems to have no effect on the pharmacokinetics of protease inhibitors although these latter agents may produce a slight increase in the bioavailability of tenofovir, which seems to be of little clinical relevance. The absence of interactions with other non-antiretroviral agents has been reported.

  18. Interacting composite fermions

    DEFF Research Database (Denmark)

    nrc762, nrc762

    2016-01-01

    Numerical studies by Wójs, Yi, and Quinn have suggested that an unconventional fractional quantum Hall effect is plausible at filling factors ν=1/3 and 1/5, provided the interparticle interaction has an unusual form for which the energy of two fermions in the relative angular momentum three channel...... dominates. The interaction between composite fermions in the second Λ level (composite fermion analog of the electronic Landau level) satisfies this property, and recent studies have supported unconventional fractional quantum Hall effect of composite fermions at ν∗=4/3 and 5/3, which manifests...... as fractional quantum Hall effect of electrons at ν=4/11, 4/13, 5/13, and 5/17. I investigate in this article the nature of the fractional quantum Hall states at ν=4/5, 5/7, 6/17, and 6/7, which correspond to composite fermions at ν∗=4/3, 5/3, and 6/5, and find that all these fractional quantum Hall states...

  19. Herb-drug interactions.

    Science.gov (United States)

    Fugh-Berman, A

    2000-01-08

    Concurrent use of herbs may mimic, magnify, or oppose the effect of drugs. Plausible cases of herb-drug interactions include: bleeding when warfarin is combined with ginkgo (Ginkgo biloba), garlic (Allium sativum), dong quai (Angelica sinensis), or danshen (Salvia miltiorrhiza); mild serotonin syndrome in patients who mix St John's wort (Hypericum perforatum) with serotonin-reuptake inhibitors; decreased bioavailability of digoxin, theophylline, cyclosporin, and phenprocoumon when these drugs are combined with St John's wort; induction of mania in depressed patients who mix antidepressants and Panax ginseng; exacerbation of extrapyramidal effects with neuroleptic drugs and betel nut (Areca catechu); increased risk of hypertension when tricyclic antidepressants are combined with yohimbine (Pausinystalia yohimbe); potentiation of oral and topical corticosteroids by liquorice (Glycyrrhiza glabra); decreased blood concentrations of prednisolone when taken with the Chinese herbal product xaio chai hu tang (sho-salko-to); and decreased concentrations of phenytoin when combined with the Ayurvedic syrup shankhapushpi. Anthranoid-containing plants (including senna [Cassia senna] and cascara [Rhamnus purshiana]) and soluble fibres (including guar gum and psyllium) can decrease the absorption of drugs. Many reports of herb-drug interactions are sketchy and lack laboratory analysis of suspect preparations. Health-care practitioners should caution patients against mixing herbs and pharmaceutical drugs.

  20. Interacting Q-balls

    CERN Document Server

    Brihaye, Yves

    2007-01-01

    We construct explicit examples of new axially symmetric, non-spinning Q-ball solutions that have not been studied so far. These solutions can be interpreted as angular excitations of the fundamental Q-balls and are related to the spherical harmonics. Correspondingly, they have higher energy and their energy densities possess two local maxima on the positive z-axis. We also study two Q-balls interacting via a potential term in 3+1 dimensions and construct examples of stationary, solitonic-like objects in (3+1)-dimensional flat space-time that consist of two interacting global scalar fields. We concentrate on configurations composed of one spinning and one non-spinning Q-ball and study the parameter-dependence of the energy and charges of the configuration. In addition, we present numerical evidence that for fixed values of the coupling constants two different types of 2-Q-ball solutions exist: solutions with defined parity, but also solutions which are asymmetric with respect to reflexion through the x-y-axis.

  1. Electromagnetic Interactions of Muons

    CERN Multimedia

    2002-01-01

    This experiment was the first in a programme of physics experiments with high-energy muons using a large spectrometer facility. The aim of this experiment is to study the inelastic scattering of muons with various targets to try to understand better the physics of virtual photon interactions over a wide range of four-momentum transfer (q$^{2}$).\\\\ \\\\ The spectrometer includes a large aperture dipole magnet (2m x 1m) of bending power $\\simeq$5 T.m and a magnetized iron filter to distinguish the scattered muons from hadrons. Drift chambers and MWPC are used before and after the magnet to detect charged products of the interaction and to allow a momentum determination of the scattered muon to an accuracy of $\\simeq$at 100 GeV/c, and an angular definition of $\\pm$ 0.1 mrad. The triggering on scattered muons relies on three planes of scintillation counter hodoscopes before and after the magnetized iron, whose magnetic field serves to eliminate triggers from low momentum muons which are produced copiously by pion d...

  2. Charged Dust Aggregate Interactions

    Science.gov (United States)

    Matthews, Lorin; Hyde, Truell

    2015-11-01

    A proper understanding of the behavior of dust particle aggregates immersed in a complex plasma first requires a knowledge of the basic properties of the system. Among the most important of these are the net electrostatic charge and higher multipole moments on the dust aggregate as well as the manner in which the aggregate interacts with the local electrostatic fields. The formation of elongated, fractal-like aggregates levitating in the sheath electric field of a weakly ionized RF generated plasma discharge has recently been observed experimentally. The resulting data has shown that as aggregates approach one another, they can both accelerate and rotate. At equilibrium, aggregates are observed to levitate with regular spacing, rotating about their long axis aligned parallel to the sheath electric field. Since gas drag tends to slow any such rotation, energy must be constantly fed into the system in order to sustain it. A numerical model designed to analyze this motion provides both the electrostatic charge and higher multipole moments of the aggregate while including the forces due to thermophoresis, neutral gas drag, and the ion wakefield. This model will be used to investigate the ambient conditions leading to the observed interactions. This research is funded by NSF Grant 1414523.

  3. Cardiolipin Interactions with Proteins.

    Science.gov (United States)

    Planas-Iglesias, Joan; Dwarakanath, Himal; Mohammadyani, Dariush; Yanamala, Naveena; Kagan, Valerian E; Klein-Seetharaman, Judith

    2015-09-15

    Cardiolipins (CL) represent unique phospholipids of bacteria and eukaryotic mitochondria with four acyl chains and two phosphate groups that have been implicated in numerous functions from energy metabolism to apoptosis. Many proteins are known to interact with CL, and several cocrystal structures of protein-CL complexes exist. In this work, we describe the collection of the first systematic and, to the best of our knowledge, the comprehensive gold standard data set of all known CL-binding proteins. There are 62 proteins in this data set, 21 of which have nonredundant crystal structures with bound CL molecules available. Using binding patch analysis of amino acid frequencies, secondary structures and loop supersecondary structures considering phosphate and acyl chain binding regions together and separately, we gained a detailed understanding of the general structural and dynamic features involved in CL binding to proteins. Exhaustive docking of CL to all known structures of proteins experimentally shown to interact with CL demonstrated the validity of the docking approach, and provides a rich source of information for experimentalists who may wish to validate predictions.

  4. Hydrophobic interactions and chemical reactivity

    NARCIS (Netherlands)

    Otto, Sijbren; Engberts, Jan B.F.N.

    2003-01-01

    This perspective describes how kinetic studies of organic reactions can be used to increase our understanding of hydrophobic interactions. In turn, our understanding of hydrophobic interactions can be used as a tool to influence chemical reactions.

  5. Interaction in English Classroom Teaching

    Institute of Scientific and Technical Information of China (English)

    金晶

    2009-01-01

    This essay mainly elaborates on the interaction in English classroom teaching.It highlights the indispensable role interaction should play in teaching process.and give out a series of methods on how to promote the application of this strategy.

  6. Novicidin interactions with phospholipid membranes

    DEFF Research Database (Denmark)

    Balakrishnan, Vijay Shankar

    Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting with lipos...

  7. HUMAN INTERACTION WITH MOBILE APPLICATIONS

    OpenAIRE

    Alin Zamfiroiu; Emanuel Herteliu; Bogdan Vintila

    2012-01-01

    Computing - human interaction is a very important paradigm because informatics applications are created to be used by people via human interaction. Nowadays mobile applications are more used so is necessarily to talk about mobile - human interaction. In this paper types of mobile devices are presented. Citizen oriented character of mobile application and his utility are described. Different means of interactions with mobile devices are analyzed and in the end of the paper direction of mobile ...

  8. Design Principles for Interactive Software

    DEFF Research Database (Denmark)

    The book addresses the crucial intersection of human-computer interaction (HCI) and software engineering by asking both what users require from interactive systems and what developers need to produce well-engineered software. Needs are expressed as......The book addresses the crucial intersection of human-computer interaction (HCI) and software engineering by asking both what users require from interactive systems and what developers need to produce well-engineered software. Needs are expressed as...

  9. On the interaction meteor complex

    Science.gov (United States)

    Rajchl, J.

    An approach to the problem of a meteoric complex called the interaction meteor complex (IMC) is applied and discussed, generalizing the idea of the interaction layer (Rajchl 1969). The role of an extended interaction of meteoroids is emphasized, both with planet surfaces and/or their satellites and with planet atmospheres, elastic or inelastic in form. The dissipation and related formative aspect are joined in one complex and compared with a topological compact. Examples of these types of interaction are presented.

  10. Electrostatic interaction of soft particles.

    Science.gov (United States)

    Ohshima, Hiroyuki

    2015-12-01

    Theories of the electrostatic interaction between two soft particles (i.e., particles covered with an ion-penetrable surface layer of polyelectrolytes) in an electrolyte solution are reviewed. Interactions of soft particles after contact of their surface layers are particularly discussed. Interaction in a salt-free medium and the discrete-charge effect are also treated.

  11. Ridge Regression for Interactive Models.

    Science.gov (United States)

    Tate, Richard L.

    1988-01-01

    An exploratory study of the value of ridge regression for interactive models is reported. Assuming that the linear terms in a simple interactive model are centered to eliminate non-essential multicollinearity, a variety of common models, representing both ordinal and disordinal interactions, are shown to have "orientations" that are favorable to…

  12. Local Interaction on Random Graphs

    Directory of Open Access Journals (Sweden)

    Hans Haller

    2010-08-01

    Full Text Available We analyze dynamic local interaction in population games where the local interaction structure (modeled as a graph can change over time: A stochastic process generates a random sequence of graphs. This contrasts with models where the initial interaction structure (represented by a deterministic graph or the realization of a random graph cannot change over time.

  13. SNP interaction pattern identifier (SIPI)

    DEFF Research Database (Denmark)

    Lin, Hui-Yi; Chen, Dung-Tsa; Huang, Po-Yu

    2016-01-01

    MOTIVATION: Testing SNP-SNP interactions is considered as a key for overcoming bottlenecks of genetic association studies. However, related statistical methods for testing SNP-SNP interactions are underdeveloped. RESULTS: We propose the SNP Interaction Pattern Identifier (SIPI), which tests 45...

  14. Interactive lectures in engineering education

    NARCIS (Netherlands)

    van Dijk, L.A.; van den Berg, G.C.; van Keulen, H.

    2001-01-01

    This article discusses an alternative approach to lecturing: the interactive lecture. In the literature, interactive teaching is forwarded as a means to increase the effectiveness of lectures. Members of lecturing staff still seem, however, reluctant to incorporate interactive teaching in their clas

  15. Bunyavirus-vector interactions.

    Science.gov (United States)

    Beaty, B J; Bishop, D H

    1988-06-01

    Recent advances in the genetics and molecular biology of bunyaviruses have been applied to understanding bunyavirus-vector interactions. Such approaches have revealed which virus gene and gene products are important in establishing infections in vectors and in transmission of viruses. However, much more information is required to understand the molecular mechanisms of persistent infections of vectors which are lifelong but apparently exert no untoward effect. In fact, it seems remarkable that LAC viral antigen can be detected in almost every cell in an ovarian follicle, yet no untoward effect on fecundity and no teratology is seen. Similarly the lifelong infection of the vector would seem to provide ample opportunity for bunyavirus evolution by genetic drift and, under the appropriate circumstances, by segment reassortment. The potential for bunyavirus evolution by segment reassortment in vectors certainly exists. For example the Group C viruses in a small forest in Brazil seem to constitute a gene pool, with the 6 viruses related alternately by HI/NT and CF reactions, which assay respectively M RNA and S RNA gene products (Casals and Whitman, 1960; Shope and Causey, 1962). Direct evidence for naturally occurring reassortant bunyaviruses has also been obtained. Oligonucleotide fingerprint analyses of field isolates of LAC virus and members of the Patois serogroup of bunyaviruses have demonstrated that reassortment does occur in nature (El Said et al., 1979; Klimas et al., 1981; Ushijima et al., 1981). Determination of the genotypic frequencies of viruses selected by the biological interactions of viruses and vectors after dual infection and segment reassortment is an important issue. Should a virus result that efficiently interacts with alternate vector species, the virus could be expressed in different circumstances with serious epidemiologic consequences. Dual infection of vectors with different viruses is not unlikely, because many bunyaviruses are sympatric in

  16. Human-Robot Interaction

    Science.gov (United States)

    Sandor, Aniko; Cross, E. Vincent, II; Chang, Mai Lee

    2015-01-01

    Human-robot interaction (HRI) is a discipline investigating the factors affecting the interactions between humans and robots. It is important to evaluate how the design of interfaces affect the human's ability to perform tasks effectively and efficiently when working with a robot. By understanding the effects of interface design on human performance, workload, and situation awareness, interfaces can be developed to appropriately support the human in performing tasks with minimal errors and with appropriate interaction time and effort. Thus, the results of research on human-robot interfaces have direct implications for the design of robotic systems. For efficient and effective remote navigation of a rover, a human operator needs to be aware of the robot's environment. However, during teleoperation, operators may get information about the environment only through a robot's front-mounted camera causing a keyhole effect. The keyhole effect reduces situation awareness which may manifest in navigation issues such as higher number of collisions, missing critical aspects of the environment, or reduced speed. One way to compensate for the keyhole effect and the ambiguities operators experience when they teleoperate a robot is adding multiple cameras and including the robot chassis in the camera view. Augmented reality, such as overlays, can also enhance the way a person sees objects in the environment or in camera views by making them more visible. Scenes can be augmented with integrated telemetry, procedures, or map information. Furthermore, the addition of an exocentric (i.e., third-person) field of view from a camera placed in the robot's environment may provide operators with the additional information needed to gain spatial awareness of the robot. Two research studies investigated possible mitigation approaches to address the keyhole effect: 1) combining the inclusion of the robot chassis in the camera view with augmented reality overlays, and 2) modifying the camera

  17. Wood–water interactions

    DEFF Research Database (Denmark)

    Engelund, Emil Tang

    2011-01-01

    must first know in which parts of the wood structure, water is located. If parts of the water in wood are held in capillaries in the wood structure, these water molecules interact with the material differently than those held within wood cell walls. In this study, the occurrence of capillary water......, for wood in equilibrium with surrounding climate in the RH range 0-99.5 %, water is only significantly present within cell walls. A structural model of a wood cell is developed in this study using Finite Element Method for predicting the mechanical performance of wood. The starting point for the model...... is the physical behaviour on the molecular level since water interferes with wood at this level. The elastic material properties of the wood cell wall are explained by the organisation of wood constituents and their properties. The effect of water as well as temperature is incorporated by considering the amount...

  18. Human Work Interaction Design

    DEFF Research Database (Denmark)

    2015-01-01

    In this paper, we review research in the emerging practice and research field of Human Work Interaction Design (HWID). We present a HWID frame-work, and a sample of 54 papers from workshops, conferences and journals from the period 2009-2014. We group the papers into six topical groups, and then at......-tempt to map these groups to the framework to find research gaps for future re-search. We find that the groups of papers cover all areas of the framework well for a variety of work and leisure domains. The area in strongest need for more research papers is the development of the holistic framework itself....... Furthermore, much focus has been on studying design sketching or implemented systems-in-use, while little attention has been paid to mature design (prototypes) or early implementation (content templates). In conclusion, we recommend an update to the framework so that it can be also useful for research...

  19. Human Work Interaction Design

    DEFF Research Database (Denmark)

    2015-01-01

    In this paper, we review research in the emerging practice and research field of Human Work Interaction Design (HWID). We present a HWID framework, and a sample of 54 HWID related papers from workshops, conferences and journals from the period 2009–2014. We group the papers into six topical groups......, and then attempt to map these groups to the framework to find research gaps for future research. We find that the groups of papers cover all areas of the framework well for a variety of work and leisure domains. The area in strongest need for more research papers is the development of the holistic framework itself....... Furthermore, much focus has been on studying design sketching or implemented systems-in-use, while little attention has been paid to mature design (prototypes) or early implementation (content templates). In conclusion, we recommend an update to the framework so that it can be also useful for research...

  20. Interactive molecular dynamics

    Science.gov (United States)

    Schroeder, Daniel V.

    2015-03-01

    Physics students now have access to interactive molecular dynamics simulations that can model and animate the motions of hundreds of particles, such as noble gas atoms, that attract each other weakly at short distances but repel strongly when pressed together. Using these simulations, students can develop an understanding of forces and motions at the molecular scale, nonideal fluids, phases of matter, thermal equilibrium, nonequilibrium states, the Boltzmann distribution, the arrow of time, and much more. This article summarizes the basic features and capabilities of such a simulation, presents a variety of student exercises using it at the introductory and intermediate levels, and describes some enhancements that can further extend its uses. A working simulation code, in html5 and javascript for running within any modern Web browser, is provided as an online supplement.

  1. Interactive molecular dynamics

    CERN Document Server

    Schroeder, Daniel V

    2015-01-01

    Physics students now have access to interactive molecular dynamics simulations that can model and animate the motions of hundreds of particles, such as noble gas atoms, that attract each other weakly at short distances but repel strongly when pressed together. Using these simulations, students can develop an understanding of forces and motions at the molecular scale, nonideal fluids, phases of matter, thermal equilibrium, nonequilibrium states, the Boltzmann distribution, the arrow of time, and much more. This article summarizes the basic features and capabilities of such a simulation, presents a variety of student exercises using it at the introductory and intermediate levels, and describes some enhancements that can further extend its uses. A working simulation code, in HTML5 and JavaScript for running within any modern Web browser, is provided as an online supplement.

  2. Parvovirus glycan interactions.

    Science.gov (United States)

    Huang, Lin-Ya; Halder, Sujata; Agbandje-McKenna, Mavis

    2014-08-01

    Members of the Parvoviridae utilize glycan receptors for cellular attachment and subsequent interactions determine transduction efficiency or pathogenic outcome. This review focuses on the identity of the glycan receptors utilized, their capsid binding footprints, and a discussion of the overlap of these sites with tropism, transduction, and pathogenicity determinants. Despite high sequence diversity between the different genera, most parvoviruses bind to negatively charged glycans, such as sialic acid and heparan sulfate, abundant on cell surface membranes. The capsid structure of these viruses exhibit high structural homology enabling common regions to be utilized for glycan binding. At the same time the sequence diversity at the common footprints allows for binding of different glycans or differential binding of the same glycan.

  3. Cultivating objects in interaction

    DEFF Research Database (Denmark)

    Hazel, Spencer

    2014-01-01

    is chapter explores patterns of repeated orientations to physical objects in interactants’ visuo-spatial and haptic surround. A number of examples are presented from advice-giving activities in various institutional settings, where participants-in-interaction initially draw on material objects...... at hand while pursuing a particular line of explanation, and then return to these objects at later intervals. e analysis suggests that the objects are afforded representational properties through their being anchored to some referent in the talk, and that participants subsequently draw...... on these associations for describing, disambiguating or clarifying aspects of the relatively complex procedural frameworks discussed in the settings. is suggests that the temporal stability of material objects available to participants makes them an ideal resource to be developed as visual motifs....

  4. Sustainable Buildings in Interaction

    DEFF Research Database (Denmark)

    Elle, Morten

    2007-01-01

    The first attempts to build sustainable buildings in Denmark were typically located on the countryside. The basic idea was to create buildings that were independent of the technical infrastructure. District heating has, however, been the dominating solution to heating in buildings in Denmark......, and the focus on sustainable building have gradually turned from special houses on the countryside to normally looking houses in the urban fabric, integrated in the technical infrastructure. Some new built urban areas in Denmark will, however, not have to be supplied with district heating – these developments...... are going to consist of passive houses. The first sustainable buildings were built by their users, and the user – building interaction still play a decisive role for the performance of the present sustainable buildings. The users have to understand how the building functions. Urban design is essential...

  5. Interactive Record Linkage

    Directory of Open Access Journals (Sweden)

    2000-12-01

    Full Text Available In order to carry out demographic analyses at individual and group levels, a manual method of linking individual event records from parish registers was developed in the late 1950s. In order to save time and to work with larger areas than small parishes, systems for automatic record linkage were developed a couple of decades later. A third method, an interactive record linkage, named Demolink, has been developed even more recently. The main new feature of the method is the possibility of linking from more than two historical sources simultaneously. This improves the process of sorting out which events belong to which individual life courses. This paper discusses how Demolink was used for record linkage in a large Norwegian parish for the period 1801-1878.

  6. Nekton Interaction Monitoring System

    Energy Technology Data Exchange (ETDEWEB)

    2017-03-15

    The software provides a real-time processing system for sonar to detect and track animals, and to extract water column biomass statistics in order to facilitate continuous monitoring of an underwater environment. The Nekton Interaction Monitoring System (NIMS) extracts and archives tracking and backscatter statistics data from a real-time stream of data from a sonar device. NIMS also sends real-time tracking messages over the network that can be used by other systems to generate other metrics or to trigger instruments such as an optical video camera. A web-based user interface provides remote monitoring and control. NIMS currently supports three popular sonar devices: M3 multi-beam sonar (Kongsberg), EK60 split-beam echo-sounder (Simrad) and BlueView acoustic camera (Teledyne).

  7. Antigen antibody interactions

    CERN Document Server

    DeLisi, Charles

    1976-01-01

    1. 1 Organization of the Immune System One of the most important survival mechanisms of vertebrates is their ability to recognize and respond to the onslaught of pathogenic microbes to which they are conti- ously exposed. The collection of host cells and molecules involved in this recognition­ 12 response function constitutes its immune system. In man, it comprises about 10 cells 20 (lymphocytes) and 10 molecules (immunoglobulins). Its ontogenic development is c- strained by the requirement that it be capable of responding to an almost limitless variety of molecular configurations on foreign substances, while simultaneously remaining inert to those on self components. It has thus evolved to discriminate, with exquisite precision, between molecular patterns. The foreign substances which induce a response, called antigens, are typically large molecules such as proteins and polysaccharides. The portions of these with which immunoglobulins interact are called epitopes or determinants. A typical protein epitope m...

  8. Pipeline‐Seabed Interaction

    DEFF Research Database (Denmark)

    Fredsøe, Jørgen

    2016-01-01

    A review of the existing research on the interaction between a pipeline and an erodible bed exposed to waves and/or currents is presented. The review covers three topics, i.e., scour, liquefaction and lateral stability of pipelines. The basic mechanism that leads to scour in two‐dimensional (2D...... on small‐scale laboratory experiments.. The state of the art of the mathematical/numerical modeling of the scour processes is presented. The associated self‐burial of the pipe is described and compared to field observations. In addition to scour, liquefaction may also constitute a risk 19 for pipeline...... stability. The cause of liquefaction and the resulting consequence for pipeline stability in a natural environment are then discussed. Finally, the lateral stability of pipelines placed on an erodible bed and exposed to waves is briefly described....

  9. Interactive Virtual Cinematography

    DEFF Research Database (Denmark)

    Burelli, Paolo

    control of the camera by the player increases the complexity of the interaction and reduces the designer's control on game storytelling. A completely designer-driven camera releases the player from the burden of controlling the point of view, but might generate undesired camera behaviours. Furthermore...... control architecture able to generate real-time, smooth and well composed camera animations. Moreover, we have designed and tested an approach to model the player's camera preferences using machine learning techniques and to tailor the automatic camera behaviour to the player and her game-play style...... to be able to accurately and smoothly control the camera. Finally, the results of a user survey, conducted to evaluate the suggested methodology for camera behaviour modelling and adaptation, shows that the resulting adaptive cinematographic experience is largely favoured by the players and it generates...

  10. Negotiated interactive observation:

    DEFF Research Database (Denmark)

    Wind, Gitte

    2008-01-01

    In this paper I discuss the possibilities and limitations of the ethnographer participating in the different on-going activities and events in highly specialised healthcare systems. The concept of participant observation is based on a number of assumptions, particularly that the ethnographer...... will become one of ‘them’ to be able to follow the steps belonging to the accepted ethnographic research practice of doing fieldwork. The character of fieldwork in highly specialised healthcare systems does not fit well with this assumption. I suggest that we need to rethink the concept of participant...... observation and I propose negotiated interactive observation as a more appropriate way to describe ethnographic fieldwork in a setting such as the hospital or the clinic....

  11. The interactive design collaboratorium

    DEFF Research Database (Denmark)

    Bødker, Susanne; Petersen, Marianne Graves; Krogh, Peter Gall

    2001-01-01

    This paper reports on experimental process in which a prototype was developed of an interactive design collaboatorium, in cooperation with a group of usability designers. In a longterm research cooperation, this usability group has changed its work practice in order to work in the design...... collaboratorium. The design collaboratorium was developed to move usability design away from a lab towards an open physical and organizational space where designer, users and engineers meet and collaborate, or work alongside each other. The cooperation between researchers and the usability gruop has resulted...... in practical experimentation in projects and in design of an experimental design collaboratorium emploing electronic whiteboards, 3D design documentation, etc. This experimental prototype has been evaluated in cooperative workshops. We report on the results of this evaluation....

  12. The Interaction Programming Problem

    Institute of Scientific and Technical Information of China (English)

    LI Rong-sheng; CHENG Ying

    2001-01-01

    Based upon the research to the economic equilibrium problems, we present a kind of new mathematical programming problem-interaction programming problem (abbreviated by IPP). The IPP is composed of two or multiple parametric programming problems which is interrelated with each other. The IPP reflects the equality and mutual benefit relationship between two (or among multiple) economic planners in an economic system. In essence, the IPP is similar to the generalized Nash equilibria (GNE) game which has been given several names in the literature: social equilibria games, pseudo-Nash equilibria games, and equilibrium programming problems. In this paper, we establish the mathematical model and some basic concepts to the IPP. We investigate the structure and the properties of the IPP. We also give a necessary and sufficient conditions for the existence of the equilibrium points to a kind of linear IPP.

  13. Glycosaminoglycan-lipoprotein interaction.

    Science.gov (United States)

    Olsson, U; Ostergren-Lundén, G; Moses, J

    2001-10-01

    Glycosaminoglycans (GAGs) bound to various proteoglycans (PGs) present in the cardiovascular system have been proposed to perform a wide range of functions. These include conferring viscoelastic properties; interacting with and modulating growth factors and enzymes; and as receptors and co-receptors in lipoprotein metabolism. Binding of apoB-100 lipoproteins, particularly low density lipoproteins (LDL), to GAGs of extracellular matrix PGs in arteries has been proposed to be an initiating event in development of atherosclerosis. This study was initiated with the aim of getting an overview of the binding patterns of different lipoprotein subclasses with individual GAG categories. We thus evaluated the interaction of lipoproteins with GAGs commonly found in the cardiovascular system using a gel mobility-shift assay developed for this purpose. The same procedure was used to measure lipoproteins binding to metabolically [(35)S]-labeled whole PGs prepared from three cell types, arterial smooth muscle cells, THP-1 macrophages and from HepG2 cells. The effect of GAG composition on PGs on lipoprotein binding was evaluated by enzymatic degradation of the carbohydrate chains. Heparan sulfate was found to bind beta very low density lipoproteins (beta-VLDL) and a chylomicron remnant model (beta-VLDL+apoE), but not LDL. Dermatan sulfate was found to bind LDL, but not beta-VLDL or the chylomicron remnant model. Chondroitin sulfate and heparin were found to bind all lipoproteins tested (LDL, beta-VLDL and beta-VLDL+apoE) although with different affinities. We can conclude that each lipoprotein subclass tested binds a specific assortment of the GAGs tested. The observations made contribute to the understanding of new and complex mechanisms by which carbohydrate and lipid metabolism may be linked.

  14. Warfarin and acetaminophen interaction.

    Science.gov (United States)

    Gebauer, Markus G; Nyfort-Hansen, Karin; Henschke, Philip J; Gallus, Alexander S

    2003-01-01

    A 74-year-old man who was receiving warfarin for atrial fibrillation experienced an abrupt increase in his international normalized ratio (INR) after taking acetaminophen. To investigate this effect, the patient's anticoagulation therapy was stabilized, and he was given acetaminophen 1 g 4 times/day for 3 days. His INR rose from 2.3 before receiving acetaminophen to 6.4 on the day after acetaminophen was discontinued. Warfarin was stopped for 2 days, and the patient's INR returned to 2.0. Warfarin was restarted at the same dosage, and his INR remained within 2.0-3.0 for 6 months. Factor VII activity decreased from 29.4% before acetaminophen therapy to 15.5% when his INR was 6.4, and factor X activity fell from 27.0% to 20.2%. His warfarin plasma concentration was 1.54 microg/ml before acetaminophen compared with 1.34 microg/ml when his INR was 6.4. No significant changes in drug intake, clinical status, diet, or lifestyle were noted. Changes in INR of this magnitude with the addition of another drug during stable anticoagulation therapy suggest a drug interaction. The lack of an increase in warfarin plasma concentration associated with the increased INR suggests a possible pharmacodynamic mechanism for this interaction. Acetaminophen or a metabolite may enhance the effect of oral coumarin anticoagulants by augmenting vitamin K antagonism. Thus, the anticoagulant effect of warfarin may be significantly elevated after only a few days of acetaminophen therapy. Patients receiving warfarin should be counseled to have their INR monitored more frequently when starting acetaminophen at dosages exceeding 2 g/day.

  15. Multiobjective Interaction Programming Problem with Interaction Constraint for Two Players

    Directory of Open Access Journals (Sweden)

    Min Jiang

    2012-01-01

    Full Text Available This paper extends an existing cooperative multi-objective interaction programming problem with interaction constraint for two players (or two agents. First, we define an s-optimal joint solution with weight vector to multi-objective interaction programming problem with interaction constraint for two players and get some properties of it. It is proved that the s-optimal joint solution with weight vector to the multi-objective interaction programming problem can be obtained by solving a corresponding mathematical programming problem. Then, we define another s-optimal joint solution with weight value to multi-objective interaction programming problem with interaction constraint for two players and get some of its properties. It is proved that the s-optimal joint solution with weight vector to multi-objective interaction programming problem can be obtained by solving a corresponding mathematical programming problem. Finally, we build a pricing multi-objective interaction programming model for a bi-level supply chain. Numerical results show that the interaction programming pricing model is better than Stackelberg pricing model and the joint pricing model.

  16. Developing a general interaction potential for hydrophobic and hydrophilic interactions.

    Science.gov (United States)

    Donaldson, Stephen H; Røyne, Anja; Kristiansen, Kai; Rapp, Michael V; Das, Saurabh; Gebbie, Matthew A; Lee, Dong Woog; Stock, Philipp; Valtiner, Markus; Israelachvili, Jacob

    2015-02-24

    We review direct force measurements on a broad class of hydrophobic and hydrophilic surfaces. These measurements have enabled the development of a general interaction potential per unit area, W(D) = -2γ(i)Hy exp(-D/D(H)) in terms of a nondimensional Hydra parameter, Hy, that applies to both hydrophobic and hydrophilic interactions between extended surfaces. This potential allows one to quantitatively account for additional attractions and repulsions not included in the well-known combination of electrostatic double layer and van der Waals theories, the so-called Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The interaction energy is exponentially decaying with decay length D(H) ≈ 0.3-2 nm for both hydrophobic and hydrophilic interactions, with the exact value of D(H) depending on the precise system and conditions. The pre-exponential factor depends on the interfacial tension, γ(i), of the interacting surfaces and Hy. For Hy > 0, the interaction potential describes interactions between partially hydrophobic surfaces, with the maximum hydrophobic interaction (i.e., two fully hydrophobic surfaces) corresponding to Hy = 1. Hydrophobic interactions between hydrophobic monolayer surfaces measured with the surface forces apparatus (SFA) are shown to be well described by the proposed interaction potential. The potential becomes repulsive for Hy < 0, corresponding to partially hydrophilic (hydrated) interfaces. Hydrated surfaces such as mica, silica, and lipid bilayers are discussed and reviewed in the context of the values of Hy appropriate for each system.

  17. HYDRODYNAMIC INTERACTIONS BETWEEN TWO BODIES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of model tests, potential flow theory, and viscous Computational Fluid Dynamics (CFD) method, the hydrodynamic interactions between two underwater bodies were investigated to determine the influencing factors, changing rule, interaction mechanism, and appropriate methods describing them. Some special phenomena were discovered in two series of near-wall interaction experiments. The mathematical model and predicting methods were presented for interacting forces near wall, and the calculation results agreed well with the experimental ones. From the comparisons among numerical results with respect to nonviscosity, numerical results with respect to viscosity, and measured results, data on the influence of viscosity on hydrodynamic interactions were obtained. For hydrodynamic interaction related to multi-body unsteady motions with six degrees of freedom that is difficult to simulate in tests, numerical predictions of unsteady interacting forces were given.

  18. Interaction Themes in Music Therapy

    DEFF Research Database (Denmark)

    Holck, Ulla

    2006-01-01

    Based on a doctoral study, the author presents a type of music therapy interaction called ‘Interaction Themes.’ These are developed from session to session and often appear in music therapy interventions with children with severe functional limitations, especially children with autism. Although...... the Interaction Themes are characterised by a relatively simple and self-generated content, they have an essential function because they contain the child’s and music therapist’s joint interaction history. They make up the context within which it is possible to create meaningful interaction with a client group...... whose expressions are often difficult to understand. The presented article describes the characteristics and functions of Interaction Themes, compares the phenomenon with music therapy case literature and delimits it in regard to other types of music therapy interaction with this client group....

  19. Interaction Themes in Music Therapy

    DEFF Research Database (Denmark)

    Holck, Ulla

    2006-01-01

    Based on a doctoral study, the author presents a type of music therapy interaction called ‘Interaction Themes.’ These are developed from session to session and often appear in music therapy interventions with children with severe functional limitations, especially children with autism. Although...... the Interaction Themes are characterised by a relatively simple and self-generated content, they have an essential function because they contain the child’s and music therapist’s joint interaction history. They make up the context within which it is possible to create meaningful interaction with a client group...... whose expressions are often difficult to understand. This presentation describes the characteristics and functions of Interaction Themes, compares the phenomenon with music therapy case literature and delimits it in regard to other types of music therapy interaction with this client group....

  20. Interactive Data Eyeslasses

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The data eyeglasses can read from the engineer’s eyes which details he needs to see on the building plans.A CMOS chip with an eyetracker in the microdisplay makes this possible.The eyeglasses are connected to a PDA,display information and respond to commands.For car designers,secret agents in the movies and jet fighter pilots,data eyeglasses-also called head-mounted displays,orHMDs for short-are everyday objects.They transport the wearer into virtual worlds or provide the user with data from the real environment.At present these devices can only display information."We want to make the eyeglasses bidirectional and interactive so thatnew areas of application can be opened up,"says Dr.Michael Scholles,business unit manager at the Fraunhofer Institute for PhotonicMicrosystems IPMS in Dresden.A group of scientists at IPMS is working on a device which incorporates eye tracking-users can influence the content presented by moving their eyes or fixing on certain points in the image.Without having to use any other devices to

  1. Unity of Fundamental Interactions

    CERN Document Server

    Sastry, R R

    2000-01-01

    The vector representation of the linearized gravitational field (the graviton field) or the so called quantum gravitodynamics which describes the motion of masses in a weak gravitational field is employed to understand the unity of the four known interactions. We propose a gauge group SU(3)xSU(2)xU(1)xU(1) for such a unified field theory. In this paper we study the SU(2)xU(1)xU(1) sector of the theory and in analogy to the electroweak mixing angle we define a gravitoweak mixing angle. The unified gauge field theory predicts the existence of three massive vector bosons, the Y+/- and the X^0. and two massless vector bosons, the photon and the graviton (in its vector representation). We determine the mass spectrum of the Y+/- and the X^0 and predict a modification to the fine structure constant under unified field conditions. Furthermore, we briefly discuss the implications of the extended object formulation for the gauge hierarchy problem.

  2. Interactive Metro Map Editing.

    Science.gov (United States)

    Wang, Yu-Shuen; Peng, Wan-Yu

    2016-02-01

    Manual editing of a metro map is essential because many aesthetic and readability demands in map generation cannot be achieved by using a fully automatic method. In addition, a metro map should be updated when new metro lines are developed in a city. Considering that manually designing a metro map is time-consuming and requires expert skills, we present an interactive editing system that considers human knowledge and adjusts the layout to make it consistent with user expectations. In other words, only a few stations are controlled and the remaining stations are relocated by our system. Our system supports both curvilinear and octilinear layouts when creating metro maps. It solves an optimization problem, in which even spaces, route straightness, and maximum included angles at junctions are considered to obtain a curvilinear result. The system then rotates each edge to extend either vertically, horizontally, or diagonally while approximating the station positions provided by users to generate an octilinear layout. Experimental results, quantitative and qualitative evaluations, and user studies show that our editing system is easy to use and allows even non-professionals to design a metro map.

  3. Strongly interacting ultracold polar molecules

    CERN Document Server

    Gadway, Bryce

    2016-01-01

    This paper reviews recent advances in the study of strongly interacting systems of dipolar molecules. Heteronuclear molecules feature large and tunable electric dipole moments, which give rise to long-range and anisotropic dipole-dipole interactions. Ultracold samples of dipolar molecules with long-range interactions offer a unique platform for quantum simulations and the study of correlated many-body physics. We provide an introduction to the physics of dipolar quantum gases, both electric and magnetic, and summarize the multipronged efforts to bring dipolar molecules into the quantum regime. We discuss in detail the recent experimental progress in realizing and studying strongly interacting systems of polar molecules trapped in optical lattices, with particular emphasis on the study of interacting spin systems and non-equilibrium quantum magnetism. Finally, we conclude with a brief discussion of the future prospects for studies of strongly interacting dipolar molecules.

  4. Herbal drugs and drug interactions

    OpenAIRE

    Gül Dülger

    2014-01-01

    Herbal drugs are defined as any form of a plant or plant product that contains a single herb or combinations of herbs that are believed to have complementary effects. Although they are considered to be safe, because they are natural, they may have various adverse effects, and may interact with other herbal products or conventional drugs. These interactions are especially important for drugs with narrow therapeutic indices.In the present study, pharmacokinetic and pharmacodynamic interactions ...

  5. Facilitative root interactions in intercrops

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, H.; Jensen, E.S.

    2005-01-01

    Facilitation takes place when plants ameliorate the environment of their neighbours, and increase their growth and survival. Facilitation occurs in natural ecosystems as well as in agroecosystems. We discuss examples of facilitative root interactions in intercropped agroecosystems; including...... intensified cropping systems using chemical and mechanical inputs also show that facilitative interactions definitely can be of significance. It is concluded that a better understanding of the mechanisms behind facilitative interactions may allow us to benefit more from these phenomena in agriculture...

  6. Interactive Raytracing: The nirt Command

    Science.gov (United States)

    2009-04-01

    Interactive Raytracing : The nirt Command by Clifford Yapp ARL-CR-624 April 2009 prepared by Quantum Research...Laboratory Aberdeen Proving Ground, MD 21005-5068 ARL-CR-624 April 2009 Interactive Raytracing : The nirt Command Clifford Yapp Quantum...DATES COVERED (From - To) June 2008–October 2008 4. TITLE AND SUBTITLE Interactive Raytracing : The nirt Command 5a. CONTRACT NUMBER W911QX-06-F

  7. Efficient Interaction in English Classroom

    Institute of Scientific and Technical Information of China (English)

    董红叶

    2013-01-01

    Lack of communicative competence will result in failure to efficiently interact with others and also weaken linguistic competence. This paper shows the importance of interaction through analyzing Klashen’s input hypothesis,emotional factors,lat⁃er Wittgenstein’s linguistic philosophy,selectivity and dynamics of languages. Different interaction activities are used in different teaching methods. A teacher needs to face all the challenges so as to find the most efficient way to teach in a language classroom.

  8. Soliton interactions of integrable models

    Energy Technology Data Exchange (ETDEWEB)

    Ruan Hangyu E-mail: hyruan@mail.nbip.net; Chen Yixin

    2003-08-01

    The solution of integrable (n+1)-dimensional KdV system in bilinear form yields a dromion solution that is localized in all directions. The interactions between two dromions are studied both in analytical and in numerical for three (n+1)-dimensional KdV-type equations (n=1, 2, 3). The same interactive properties between two dromions (solitons) are revealed for these models. The interactions between two dromions (solitons) may be elastic or inelastic for different form of solutions.

  9. Soliton interactions of integrable models

    CERN Document Server

    Ruan Hang Yu

    2003-01-01

    The solution of integrable (n+1)-dimensional KdV system in bilinear form yields a dromion solution that is localized in all directions. The interactions between two dromions are studied both in analytical and in numerical for three (n+1)-dimensional KdV-type equations (n=1, 2, 3). The same interactive properties between two dromions (solitons) are revealed for these models. The interactions between two dromions (solitons) may be elastic or inelastic for different form of solutions.

  10. Searching for unwanted drug interactions

    OpenAIRE

    Ognjenović, Dejan

    2014-01-01

    Drug interactions are interweaving effects between two or more drugs that can have desirable or harmful effects on patients health. In this thesis we for searched harmful drug interactions. Our approach is based on two machine learning algorithms for association rule mining. We use two given hierarchies, one for drugs (ATC), the other for diseases (ICD), and one proprietary interaction database LexiComp. A generalized association rule algorithm tries to find rules that contain basic ...

  11. Nutrition and parasite interaction.

    Science.gov (United States)

    Coop, R L; Holmes, P H

    1996-01-01

    This overview focuses on the interaction between nutritional status and gastrointestinal nematode infection in ruminants and considers: (i) the influence of the parasite on host metabolism; and (ii) the effect of host nutrition on the establishment and survival of parasite populations, the development of the host-immune response and the pathophysiology of infection. Gastrointestinal nematodes reduce voluntary feed intake and efficiency of feed utilisation, a key feature being an increased endogenous loss of protein into the gastrointestinal tract. Overall there is movement of protein from productive processes into repair of the gastrointestinal tract, synthesis of plasma proteins and mucoprotein production. Although reduction in feed intake is a major factor contributing to the reduced performance of parasitised ruminants, the underlying mechanisms of the anorexia are poorly understood. Supplementation of the diet with additional protein does not appear to affect initial establishment of nematode infections but the pathophysiological consequences are generally more severe on lower planes of protein nutrition. The main effect of protein supplementation is to increase the rate of acquisition of immunity and increase resistance to reinfection and this has been associated with an enhanced cellular immune response in the gastrointestinal mucosa. The unresponsiveness of the young lamb can be improved by dietary protein supplementation. Recent trials have shown that growing sheep offered a free choice between a low and a high protein ration are able to modify their diet selection in order to alleviate the increase in protein requirements which result from gastrointestinal nematode infection. Studies on the influence of nutrition on the expression of genotype have shown that the benefits of a superior genotype are not lost on a low protein diet whereas a high protein diet can partially emeliorate the disadvantages of an inferior genotype. In addition to dietary protein

  12. Mobile Collocated Interactions With Wearables

    DEFF Research Database (Denmark)

    Lucero, Andrés; Wilde, Danielle; Robinson, Simon

    2015-01-01

    powerful, and closer to our bodies. Therefore, mobile collocated interactions research, which originally looked at smartphones and tablets, will inevitably move towards fully integrated wearable technologies. The focus of this workshop is to bring together a community of researchers, designers...... and practitioners to explore the potential of extending mobile collocated interactions from, through and around the body using wearable technologies.......Research on mobile collocated interactions has been looking at situations in which collocated users engage in collaborative activities using their mobile devices, thus going from personal/individual toward shared/multiuser experiences and interactions. However, computers are getting smaller, more...

  13. RKKY interaction in bilayer graphene

    Science.gov (United States)

    Mohammadi, Yawar; Moradian, Rostam

    2015-12-01

    We study the RKKY interaction between two magnetic impurities located on the same layer (intralayer case) or on different layers (interlayer case) in undoped bilayer graphene (BLG) in the four-bands model, by directly calculating the Green functions in the eigenvalues and eigenvectors representation. Our results show that both intra- and interlayer RKKY interactions between two magnetic impurities located on the same (opposite) sublattice are always ferromagnetic (antiferromagnetic). Furthermore we find unusual long-distance decay of the RKKY interaction in BLG. The intralyer RKKY interactions between two magnetic impurities located on the same sublattice, J AnAn(R) and J BnBn(R), decay closely as 1 /R6 and 1 /R2 at large impurity distances respectively, but when they are located on opposite sublattices the RKKY interactions exhibit 1 /R4 decays approximately. In the interlayer case, the RKKY interactions between two magnetic impurities located on the same sublattice show a decay close to 1 /R4 at large impurity distances, but if two magnetic impurities be on opposite sublattices the RKKY interactions, J A1B2(R) and J B1A2(R), decay closely as 1 /R6 and 1 /R2 respectively. Both intra- and interlayer RKKY interactions have anisotropic oscillatory factors which for intralayer case is equal to that for single layer graphene (SLG). Our results at weak and strong interlayer coupling limits reduce to the RKKY interaction of SLG and that of BLG in the two-bands approximation respectively.

  14. Dark patterns in proxemic interactions

    DEFF Research Database (Denmark)

    Greenberg, Saul; Boring, Sebastian; Vermeulen, Jo

    2014-01-01

    Proxemics theory explains peoples' use of interpersonal distances to mediate their social interactions with others. Within Ubicomp, proxemic interaction researchers argue that people have a similar social understanding of their spatial relations with nearby digital devices, which can be exploited...... to better facilitate seamless and natural interactions. To do so, both people and devices are tracked to determine their spatial relationships. While interest in proxemic interactions has increased over the last few years, it also has a dark side: knowledge of proxemics may (and likely will) be easily...

  15. Theoretical studies of molecular interactions

    Energy Technology Data Exchange (ETDEWEB)

    Lester, W.A. Jr. [Univ. of California, Berkeley (United States)

    1993-12-01

    This research program is directed at extending fundamental knowledge of atoms and molecules including their electronic structure, mutual interaction, collision dynamics, and interaction with radiation. The approach combines the use of ab initio methods--Hartree-Fock (HF) multiconfiguration HF, configuration interaction, and the recently developed quantum Monte Carlo (MC)--to describe electronic structure, intermolecular interactions, and other properties, with various methods of characterizing inelastic and reaction collision processes, and photodissociation dynamics. Present activity is focused on the development and application of the QMC method, surface catalyzed reactions, and reorientation cross sections.

  16. INCA- INTERACTIVE CONTROLS ANALYSIS

    Science.gov (United States)

    Bauer, F. H.

    1994-01-01

    The Interactive Controls Analysis (INCA) program was developed to provide a user friendly environment for the design and analysis of linear control systems, primarily feedback control systems. INCA is designed for use with both small and large order systems. Using the interactive graphics capability, the INCA user can quickly plot a root locus, frequency response, or time response of either a continuous time system or a sampled data system. The system configuration and parameters can be easily changed, allowing the INCA user to design compensation networks and perform sensitivity analysis in a very convenient manner. A journal file capability is included. This stores an entire sequence of commands, generated during an INCA session into a file which can be accessed later. Also included in INCA are a context-sensitive help library, a screen editor, and plot windows. INCA is robust to VAX-specific overflow problems. The transfer function is the basic unit of INCA. Transfer functions are automatically saved and are available to the INCA user at any time. A powerful, user friendly transfer function manipulation and editing capability is built into the INCA program. The user can do all transfer function manipulations and plotting without leaving INCA, although provisions are made to input transfer functions from data files. By using a small set of commands, the user may compute and edit transfer functions, and then examine these functions by using the ROOT_LOCUS, FREQUENCY_RESPONSE, and TIME_RESPONSE capabilities. Basic input data, including gains, are handled as single-input single-output transfer functions. These functions can be developed using the function editor or by using FORTRAN- like arithmetic expressions. In addition to the arithmetic functions, special functions are available to 1) compute step, ramp, and sinusoid functions, 2) compute closed loop transfer functions, 3) convert from S plane to Z plane with optional advanced Z transform, and 4) convert from Z

  17. Measuring L2 speakers’ interactional ability using interactive speech tasks

    NARCIS (Netherlands)

    van Batenburg, Eline S. L.; Oostdam, Ron J.; van Gelderen, Amos J. S.; de Jong, Nivja H.

    2016-01-01

    This article explores ways to assess interactional performance, and reports on the use of a test format that standardizes the interlocutor?s linguistic and interactional contributions to the exchange. It describes the construction and administration of six scripted speech tasks (instruction, advice,

  18. Discovering functional interaction patterns in protein-protein interaction networks

    Directory of Open Access Journals (Sweden)

    Can Tolga

    2008-06-01

    Full Text Available Abstract Background In recent years, a considerable amount of research effort has been directed to the analysis of biological networks with the availability of genome-scale networks of genes and/or proteins of an increasing number of organisms. A protein-protein interaction (PPI network is a particular biological network which represents physical interactions between pairs of proteins of an organism. Major research on PPI networks has focused on understanding the topological organization of PPI networks, evolution of PPI networks and identification of conserved subnetworks across different species, discovery of modules of interaction, use of PPI networks for functional annotation of uncharacterized proteins, and improvement of the accuracy of currently available networks. Results In this article, we map known functional annotations of proteins onto a PPI network in order to identify frequently occurring interaction patterns in the functional space. We propose a new frequent pattern identification technique, PPISpan, adapted specifically for PPI networks from a well-known frequent subgraph identification method, gSpan. Existing module discovery techniques either look for specific clique-like highly interacting protein clusters or linear paths of interaction. However, our goal is different; instead of single clusters or pathways, we look for recurring functional interaction patterns in arbitrary topologies. We have applied PPISpan on PPI networks of Saccharomyces cerevisiae and identified a number of frequently occurring functional interaction patterns. Conclusion With the help of PPISpan, recurring functional interaction patterns in an organism's PPI network can be identified. Such an analysis offers a new perspective on the modular organization of PPI networks. The complete list of identified functional interaction patterns is available at http://bioserver.ceng.metu.edu.tr/PPISpan/.

  19. Strategic interaction and conventions

    Directory of Open Access Journals (Sweden)

    Espinosa, María Paz

    2012-03-01

    Full Text Available The scope of the paper is to review the literature that employs coordination games to study social norms and conventions from the viewpoint of game theory and cognitive psychology. We claim that those two alternative approaches are in fact complementary, as they provide different insights to explain how people converge to a unique system of self-fulfilling expectations in presence of multiple, equally viable, conventions. While game theory explains the emergence of conventions relying on efficiency and risk considerations, the psychological view is more concerned with frame and labeling effects. The interaction between these alternative (and, sometimes, competing effects leads to the result that coordination failures may well occur and, even when coordination takes place, there is no guarantee that the convention eventually established will be the most efficient.

    El objetivo de este artículo es presentar la literatura que emplea los juegos de coordinación para el estudio de normas y convenciones sociales, que se han analizado tanto desde el punto de vista de la teoría de juegos como de la psicología cognitiva. Argumentamos en este trabajo que estos dos enfoques alternativos son en realidad complementarios, dado que ambos contribuyen al entendimiento de los procesos mediante los cuales las personas llegan a coordinarse en un único sistema de expectativas autorrealizadas, en presencia de múltiples convenciones todas ellas igualmente viables. Mientras que la teoría de juegos explica la aparición de convenciones basándose en argumentos de eficiencia y comportamientos frente al riesgo, el enfoque de la psicología cognitiva utiliza en mayor medida consideraciones referidas al entorno y naturaleza de las decisiones. La interacción entre estos efectos diferentes (y en ocasiones, rivales desemboca con frecuencia en fallos de coordinación y, aun cuando la coordinación se produce, no hay garantía de que la convención en vigor sea la m

  20. Environmental Interactions Working Group Report

    Science.gov (United States)

    Stevens, N. J.; Wiskerchen, M.

    1984-01-01

    Interactions between spacecraft systems and the space charged particle environment are reviewed and recommendations are presented for both near-term and far-term research considerations. Transient environment models, large space structures, solar and nuclear power systems/environment interactions, single event upsets, material degradation, and planetary missions are addressed.

  1. Distinguishing Ordinal and Disordinal Interactions

    Science.gov (United States)

    Widaman, Keith F.; Helm, Jonathan L.; Castro-Schilo, Laura; Pluess, Michael; Stallings, Michael C.; Belsky, Jay

    2012-01-01

    Re-parameterized regression models may enable tests of crucial theoretical predictions involving interactive effects of predictors that cannot be tested directly using standard approaches. First, we present a re-parameterized regression model for the Linear x Linear interaction of 2 quantitative predictors that yields point and interval estimates…

  2. Expertise revisited I: Interactional Expertise

    CERN Document Server

    Collins, Harry

    2016-01-01

    The notion of interactional expertise is explained starting with its origins and discussing its many applications. Interactional expertise is the ability to understand a technical area purely be deeply immersed in its 'practice-language' without actually practising. One of its many applications is to explain how large sciences are managed.

  3. Documentation of Appliances & Interaction Devices

    DEFF Research Database (Denmark)

    2004-01-01

    The interaction devices and appliances explored in the WorkSPACE project, address spatial computing in the context of work. We have developed and explored a range of appliances and interaction devices. The scope has been to develop tools for support of collaboration by mixing digital and physical...

  4. Interactive Information Visualization in Neuroimaging

    DEFF Research Database (Denmark)

    Nielsen, Finn Årup; Hansen, Lars Kai

    1998-01-01

    We describe a virtual environment for interactive visualization of 3D neuroimages. The environment is implemented in VRML and we will discuss the viability and limitation of this platform......We describe a virtual environment for interactive visualization of 3D neuroimages. The environment is implemented in VRML and we will discuss the viability and limitation of this platform...

  5. Urban Interaction and Affective Experience

    DEFF Research Database (Denmark)

    Fritsch, Jonas; Brynskov, Martin

    2008-01-01

    in favor of three points in that direction: First we argue that interaction – and the definition of interaction – is central to unfold the potential of digital urban media, from big, shared screens and media facades to small pri-vate, networked mobile and embedded platforms. Then we argue that an affective...

  6. 3-way Anova Interactions: Deconstructed

    OpenAIRE

    Phil Ender

    2008-01-01

    Three approaches to understanding 3-way anova interactions will be presented: 1) a conceptual approach, 2) an anova approach and 3) a regression approach using dummy coding. The three approaches are illustrated through the use of a synthetic dataset with a significant 3-way interaction.

  7. Interactive Flow in Exercise Pedagogy

    Science.gov (United States)

    Lloyd, Rebecca; Smith, Stephen

    2006-01-01

    A phenomenology of the bodily experience of interactive flow adds to Csikszentmihalyi's flow theory. Whereas Csikszentmihalyi attended to teachers' and students' experiences of flow separately, this inquiry explores flow through three water-inspired layers of physical interaction between fitness professionals and their clients. Teaching fitness is…

  8. Temporal form in interaction design

    DEFF Research Database (Denmark)

    Vallgårda, Anna; Winther, Morten Trøstrup; Mørch, Nina;

    2015-01-01

    a nuanced account of what temporal form is in interaction design, and we look at related work synthesizing what we already know of the temporal concerns in interaction design and HCI. In the second part we present a design experiment through which we explore the experiential qualities of a set of 11 simple...

  9. Narrative Cognition in Interactive Systems

    DEFF Research Database (Denmark)

    Bruni, Luis Emilio; Baceviciute, Sarune; Arief, Mohammed

    2014-01-01

    In this article we explore some of the methodological problems related to characterizing cognitive aspects of involvement with interactive narratives using well known EEG/ERP techniques. To exemplify this, we construct an experimental EEG-ERP set-up with an interactive narrative that considers...

  10. Eye Movements in Gaze Interaction

    DEFF Research Database (Denmark)

    Møllenbach, Emilie; Hansen, John Paulin; Lillholm, Martin

    2013-01-01

    Gaze as a sole input modality must support complex navigation and selection tasks. Gaze interaction combines specific eye movements and graphic display objects (GDOs). This paper suggests a unifying taxonomy of gaze interaction principles. The taxonomy deals with three types of eye movements: fix...

  11. The CHI 2013 interactive schedule

    DEFF Research Database (Denmark)

    Satyanarayan, Arvind; Strazzulla, Daniel; Klokmose, Clemens Nylandsted

    2013-01-01

    is available. The CHI'13 Interactive Schedule helps attendees navigate this wealth of video content in order to identify events they would like to attend. It consists of a number of large display screens throughout the conference venue which cycle through a video playlist of events. Attendees can interact...

  12. Nitrogen interactions at metal surfaces

    NARCIS (Netherlands)

    Gleeson, M. A.; Kleyn, A. W.

    2013-01-01

    Molecular beam experiments with specially prepared beams allow the study of the interaction of very reactive species with surfaces. In the present case the interaction of N-atoms with Ag(1 1 1) is studied. The energy of the atoms is around 5 eV, precisely between the classical energy regimes of seed

  13. Tangible Interaction in Industrial Plants

    DEFF Research Database (Denmark)

    Jensen, Mads Vedel

    With this dissertation, I answer the overall research question, which has been my focus through my research activities: How can interaction designers design user interfaces that invite, and allow interaction based on skilled practice in industrial contexts? My assumption is that the rapid invasio...

  14. Hadronic interactions and nuclear physics

    CERN Document Server

    Beane, S R

    2008-01-01

    I give an overview of efforts in the last year to calculate interactions among hadrons using lattice QCD. Results discussed include the extraction of low-energy phase shifts and three-body interactions, and the study of pion and kaon condensation. A critical appraisal is offered of recent attempts to calculate nucleon-nucleon and nucleon-hyperon potentials on the lattice.

  15. Results-Based Interaction Design

    Science.gov (United States)

    Weiss, Meredith

    2008-01-01

    Interaction design is a user-centered approach to development in which users and their goals are the driving force behind a project's design. Interaction design principles are fundamental to the design and implementation of effective websites, but they are not sufficient. This article argues that, to reach its full potential, a website should also…

  16. A Critique of Interactional Approach

    Institute of Scientific and Technical Information of China (English)

    Bao Fang

    2011-01-01

    Interactional approach is a very important theory in second language acquisition, including the input hypothesis and interaction hypothesis. This article first presents an exposition of these two hypotheses, and continues with a critical evaluation of them. Finally, the article concludes with the pedagogical implications of the approach.

  17. Moderating influences on interactivity effects

    NARCIS (Netherlands)

    Voorveld, H.; van Noort, G.

    2012-01-01

    Research on website interactivity is widespread and there are two important reasons for this popularity. The first is that interactivity is assumed to be the key characteristic that distinguishes communication in traditional media from communication in new media such as websites (Chung and Zhao, 200

  18. Emotional intelligence and social interaction.

    Science.gov (United States)

    Lopes, Paulo N; Brackett, Marc A; Nezlek, John B; Schütz, Astrid; Sellin, Ina; Salovey, Peter

    2004-08-01

    Two studies found positive relationships between the ability to manage emotions and the quality of social interactions, supporting the predictive and incremental validity of an ability measure of emotional intelligence, the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT). In a sample of 118 American college students (Study 1), higher scores on the managing emotions subscale of the MSCEIT were positively related to the quality of interactions with friends, evaluated separately by participants and two friends. In a diary study of social interaction with 103 German college students (Study 2), managing emotions scores were positively related to the perceived quality of interactions with opposite sex individuals. Scores on this subscale were also positively related to perceived success in impression management in social interactions with individuals of the opposite sex. In both studies, the main findings remained statistically significant after controlling for Big Five personality traits.

  19. Synergistic Interactions in Multispecies Biofilms

    DEFF Research Database (Denmark)

    Ren, Dawei

    between plasmid host range and composition of the recipient community was investigated in Manuscript 5 by comparing plasmid permissiveness in single populations and in a microbial community composed of 15 soil strains. By use of flow cytometry (FCM) and 16S rRNA gene sequencing, the IncP1 plasmid, pKJK10...... bacterial species, the study to elucidate the impact of interaction networks on the multispecies biofilms in natural ecosystems, especially in soil, is still at an early stage. The diverse patterns of interactions within the mixed communities as well as the predatorprey relationship between protozoa...... interactions in this four-species biofilm model community. Manuscript 2 presents the further application of this developed approach on evaluating the synergistic/antagonistic interactions in multispecies biofilms composed of seven soil isolates. 63% of the four-species biofilms were found to interact...

  20. Noncovalent interaction of carbon nanostructures.

    Science.gov (United States)

    Umadevi, Deivasigamani; Panigrahi, Swati; Sastry, Garikapati Narahari

    2014-08-19

    The potential application of carbon nanomaterials in biology and medicine increases the necessity to understand the nature of their interactions with living organisms and the environment. The primary forces of interaction at the nano-bio interface are mostly noncovalent in nature. Quantifying such interactions and identifying various factors that influence such interactions is a question of outstanding fundamental interest in academia and industry. In this Account, we have summarized our recent studies in understanding the noncovalent interactions of carbon nanostructures (CNSs), which were obtained by employing first-principles calculations on various model systems representing carbon nanotubes (CNTs) and graphene. Bestowed with an extended sp(2) carbon network, which is a common feature in all of these nanostructures, they exhibit π-π interactions with aromatic molecules (benzene, naphthalene, nucleobases, amino acids), cation-π type of interactions with metal ions, anion-π interactions with anions, and other XH···π type of interactions with various small molecules (H2O, NH3, CH4, H2, etc.). CNTs are wrapped-up forms of two-dimensional graphene, and hence, it is interesting to compare the binding abilities of these two allotropes that differ in their curvature. The chirality and curvature of CNSs appear to play a major role in determining the structural, energetic, and functional properties. Flat graphene shows stronger noncovalent interactions than the curved nanotubes toward various substrates. Understanding the interactions of CNSs with organic molecules and biomolecules has gained a great deal of research interest because of their potential applications in various fields. Aromatic hydrocarbons show a strong propensity to interact with CNSs via the π-π mode of interaction rather than CH···π interaction. As DNA sequencing appears to be one of the most important potential applications of carbon nanomaterials, the study of CNS

  1. Controllability in protein interaction networks.

    Science.gov (United States)

    Wuchty, Stefan

    2014-05-13

    Recently, the focus of network research shifted to network controllability, prompting us to determine proteins that are important for the control of the underlying interaction webs. In particular, we determined minimum dominating sets of proteins (MDSets) in human and yeast protein interaction networks. Such groups of proteins were defined as optimized subsets where each non-MDSet protein can be reached by an interaction from an MDSet protein. Notably, we found that MDSet proteins were enriched with essential, cancer-related, and virus-targeted genes. Their central position allowed MDSet proteins to connect protein complexes and to have a higher impact on network resilience than hub proteins. As for their involvement in regulatory functions, MDSet proteins were enriched with transcription factors and protein kinases and were significantly involved in bottleneck interactions, regulatory links, phosphorylation events, and genetic interactions.

  2. Interaction themes in music therapy

    DEFF Research Database (Denmark)

    Holck, Ulla

    2004-01-01

    Based on a doctoral study, the author presents a type of music therapyinteraction called ?Interaction Themes.? These are developed fromsession to session and often appear in music therapy interventions withchildren with severe functional limitations, especially children withautism. Although...... the Interaction Themes are characterised by arelatively simple and self-generated content, they have an essentialfunction because they contain the child?s and music therapist?s jointinteraction history. They make up the context within which it ispossible to create meaningful interaction with a client group...... whoseexpressions are often difficult to understand. The article describes thecharacteristics and functions of Interaction Themes, compares thephenomenon with music therapy case literature and delimits it in regardto other types of music therapy interaction with this client group. Theresults are described through...

  3. Brownian motion of interacting particles

    Energy Technology Data Exchange (ETDEWEB)

    Ackerson, B.J.

    1976-01-01

    Guided by the descriptions which are used to describe noninteracting particles, it is argued that the generalized Smoluchowski equation, including the hydrodynamic interaction and corrections for ion cloud effects may be used to describe interacting particles for the temporal and spatial regimes probed by light beating spectroscopy. This equation is then used to find cumulants of decay of the intermediate scattering function. The generalized Smoluchowski equation is reduced to a simple diffusion equation. The resulting diffusion constant depends upon the interparticle forces and is reminiscent of some early descriptions for interacting systems. The generalized Smoluchowski equation is solved for the model system of a linear chain of colloidal particles interacting via nearest neighbor harmonic couplings. The results for the intermediate scattering function and the static structure factor are very reminiscent of corresponding measurements made for interacting colloidal systems. (GHT)

  4. Plant biotic interactions

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    occurring after infestation by olive fly larvae. The last research article by Niu et al.(2016) describes a growth-promoting rhizobacterium that primes induced systemic resistance by suppressing a host R gene-targeting micro RNA pairs and activating host immune responses. This finding further supports the important roles of plant endogenous small RNAs in plant-pathogen interactions. Hailing Jin, Professor Special Issue Editor UC President’s Chair Director of Genetics, Genomics and Bioinformatics Graduate Program, Center for Plant Cell Biology, Institute for Integrative Genome Biology, University of California, Riverside, USA doi:10.1111/jipb.12476 ©2016 Institute of Botany, Chinese Academy of Sciences REFERENCES Alagna F, Kal enbach M, Pompa A, De Marchis F, Rao R, Baldwin IT, Bonaventure G, Baldoni L (2016) Olive fruits infested with olive fly larvae respond with an ethylene burst and the emission of specific volatiles. J Integr Plant Biol 58:413–425 Castiblanco LF, Sundin GW (2016) New insights on molecular regulation of biofilm formation in plant-associated bacteria. J Integr Plant Biol 58:362–372 da GraSca JV, Douhan GW, Halbert SE, Keremane ML, Lee RF, Vidalakis G, Zhao H (2016) Huanglongbing: An overview of a complex pathosystem ravaging the world’s citrus. J Integr Plant Biol 58:373–387 Giovino A, Martinel i F, Saia S (2016) Rhynchophorus ferrugineus attack affects a group of compounds rather than rearranging Phoenix canariensis metabolic pathways. J Integr Plant Biol 58:388–396 Huang J, Yang M, Zhang X (2016) The function of smal RNAs in plant biotic stress response. J Integr Plant Biol 58:312–327 Kaloshian I, Wal ing LL (2016) Hemipteran and dipteran pests: Effectors and plant host immune regulators. J Integr Plant Biol 58:350–361 Mermigka G, Verret F, Kalantidis K (2016) RNA silencing movement in plants. J Integr Plant Biol 58:328–342 Niu D, Xia J, Jiang C, Qi B, Ling X, Lin S, Zhang W, Guo J, Jin H, Zhao H (2016) Bacil us cereus AR156

  5. Final State Interactions Effects in Neutrino-Nucleus Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Golan, Tomasz [Univ. of Wroctaw (Poland); Juszczak, Cezary [Univ. of Wroctaw (Poland); Sobczyk, Jan T. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    2012-07-01

    Final State Interactions effects are discussed in the context of Monte Carlo simulations of neutrino-nucleus interactions. A role of Formation Time is explained and several models describing this effect are compared. Various observables which are sensitive to FSI effects are reviewed including pion-nucleus interaction and hadron yields in backward hemisphere. NuWro Monte Carlo neutrino event generator is described and its ability to understand neutral current $\\pi^0$ production data in $\\sim 1$ GeV neutrino flux experiments is demonstrated.

  6. Interaction between learners in an interactive learning environment

    DEFF Research Database (Denmark)

    Davidsen, Jacob; Georgsen, Marianne

    and how we are going to teach children of tomorrow. It is widely believed, also by policy makers, that technology can transform learning environments for both teachers and students. Over the past 10 years, the Danish government - like those in other countries - has been investing in interactive....... 2010). However, such a learning design still requires a teacher to facilitate, manage and lead the participation and interaction patterns of the learners. In this paper, we present an empirical long term study of class room interaction in a setting where technology is introduced to enhance...... collaboration between peer learners. For one year, the authors have followed the development of a learning practice and a learning design based on use of interactive touch screens. Methodologically, this research is based on action research, dialogue design and ethnographic methods. More than 150 hours of video...

  7. Hemoglobin interacting proteins and implications of spectrin hemoglobin interaction.

    Science.gov (United States)

    Basu, Avik; Chakrabarti, Abhijit

    2015-10-14

    In this report we have analyzed interacting partners of hemoglobin inside erythrocyte and sought possible implications of hemoglobin-spectrin interaction. Our list of identified cytosolic hemoglobin interacting proteins includes redox regulators like peroxiredoxin-2, Cu-Zn superoxide dismutase, catalase, aldehyde dehydrogenase-1, flavin reductase and chaperones like HSP70, α-hemoglobin stabilizing protein. Others include metabolic enzymes like carbonic anhydrase-1, selenium binding protein-1, purine nucleoside phosphorylase and nucleoside diphosphate kinase. Additionally, various membrane proteins like α and β spectrin, ankyrin, band3, protein4.1, actin and glyceraldehyde 3 phosphate dehydrogenase have been shown to interact with hemoglobin. Our result indicates that major membrane skeleton protein spectrin, that also has a chaperone like activity, helps to fold the unstable alpha-globin chains in vitro. Taken together our results could provide insight into a protein network evolved around hemoglobin molecule inside erythrocyte that may add a new perspective in understanding the hemoglobin function and homeostasis.

  8. Interactions, Starbursts, and Star Formation

    Directory of Open Access Journals (Sweden)

    Johan H. Knapen

    2015-12-01

    Full Text Available We study how interactions between galaxies affect star formation within them by considering a sample of almost 1500 of the nearest galaxies, all within a distance of ∼45 Mpc. We use the far-IR emission to define the massive star formation rate (SFR, and then normalise the SFR by the stellar mass of the galaxy to obtain the specific star formation rate (SSFR. We explore the distribution of (SSFR with morphological type and with stellar mass. We calculate the relative enhancement of SFR and SSFR for each galaxy by normalising them by the median SFR and SSFR values of individual control samples of similar non-interacting galaxies. We find that both the median SFR and SSFR are enhanced in interacting galaxies, and more so as the degree of interaction is higher. The increase is moderate, reaching a maximum of a factor of 1.9 for the highest degree of interaction (mergers. While the SFR and SSFR are enhanced statistically by interactions, in many individual interacting galaxies they are not enhanced at all. Our study is based on a representative sample of nearby galaxies and should be used to place constraints on studies based on samples of galaxies at larger distances.

  9. Detecting mutually exclusive interactions in protein-protein interaction maps.

    KAUST Repository

    Sánchez Claros, Carmen

    2012-06-08

    Comprehensive protein interaction maps can complement genetic and biochemical experiments and allow the formulation of new hypotheses to be tested in the system of interest. The computational analysis of the maps may help to focus on interesting cases and thereby to appropriately prioritize the validation experiments. We show here that, by automatically comparing and analyzing structurally similar regions of proteins of known structure interacting with a common partner, it is possible to identify mutually exclusive interactions present in the maps with a sensitivity of 70% and a specificity higher than 85% and that, in about three fourth of the correctly identified complexes, we also correctly recognize at least one residue (five on average) belonging to the interaction interface. Given the present and continuously increasing number of proteins of known structure, the requirement of the knowledge of the structure of the interacting proteins does not substantially impact on the coverage of our strategy that can be estimated to be around 25%. We also introduce here the Estrella server that embodies this strategy, is designed for users interested in validating specific hypotheses about the functional role of a protein-protein interaction and it also allows access to pre-computed data for seven organisms.

  10. Detecting mutually exclusive interactions in protein-protein interaction maps.

    Directory of Open Access Journals (Sweden)

    Carmen Sánchez Claros

    Full Text Available Comprehensive protein interaction maps can complement genetic and biochemical experiments and allow the formulation of new hypotheses to be tested in the system of interest. The computational analysis of the maps may help to focus on interesting cases and thereby to appropriately prioritize the validation experiments. We show here that, by automatically comparing and analyzing structurally similar regions of proteins of known structure interacting with a common partner, it is possible to identify mutually exclusive interactions present in the maps with a sensitivity of 70% and a specificity higher than 85% and that, in about three fourth of the correctly identified complexes, we also correctly recognize at least one residue (five on average belonging to the interaction interface. Given the present and continuously increasing number of proteins of known structure, the requirement of the knowledge of the structure of the interacting proteins does not substantially impact on the coverage of our strategy that can be estimated to be around 25%. We also introduce here the Estrella server that embodies this strategy, is designed for users interested in validating specific hypotheses about the functional role of a protein-protein interaction and it also allows access to pre-computed data for seven organisms.

  11. Diatomic interaction potential theory applications

    CERN Document Server

    Goodisman, Jerry

    2013-01-01

    Diatomic Interaction Potential Theory, Volume 2: Applications discusses the variety of applicable theoretical material and approaches in the calculations for diatomic systems in their ground states. The volume covers the descriptions and illustrations of modern calculations. Chapter I discusses the calculation of the interaction potential for large and small values of the internuclear distance R (separated and united atom limits). Chapter II covers the methods used for intermediate values of R, which in principle means any values of R. The Hartree-Fock and configuration interaction schemes des

  12. Aligned interactions in cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Kempa, J., E-mail: kempa@pw.plock.pl [Warsaw University of Technology Branch Plock (Poland)

    2015-12-15

    The first clean Centauro was found in cosmic rays years many ago at Mt Chacaltaya experiment. Since that time, many people have tried to find this type of interaction, both in cosmic rays and at accelerators. But no one has found a clean cases of this type of interaction.It happened finally in the last exposure of emulsion at Mt Chacaltaya where the second clean Centauro has been found. The experimental data for both the Centauros and STRANA will be presented and discussed in this paper. We also present our comments to the intriguing question of the existence of a type of nuclear interactions at high energy with alignment.

  13. Cytokine-Leukotriene Receptor Interactions

    Directory of Open Access Journals (Sweden)

    Marek Rola-Pleszczynski

    2007-01-01

    Full Text Available Biochemical and pharmacological studies have identified the structure of leukotrienes, the pathways that lead to their synthesis, and the signaling events they trigger when they interact with their cognate receptors. A privileged interaction exists between these lipid mediators and another group of molecules essential for inflammation and immune modulation, namely, cytokines. Whereas leukotrienes can trigger the synthesis and release of selected cytokines in distinct cell populations, many cytokines can affect cellular responsiveness to leukotrienes by modulating leukotriene receptor expression. As we progressively begin to unravel these complex interactions, new areas of cell-cell communication and eventual therapeutic interventions will emerge.

  14. Interactive 3D multimedia content

    CERN Document Server

    Cellary, Wojciech

    2012-01-01

    The book describes recent research results in the areas of modelling, creation, management and presentation of interactive 3D multimedia content. The book describes the current state of the art in the field and identifies the most important research and design issues. Consecutive chapters address these issues. These are: database modelling of 3D content, security in 3D environments, describing interactivity of content, searching content, visualization of search results, modelling mixed reality content, and efficient creation of interactive 3D content. Each chapter is illustrated with example a

  15. Quantum interaction. Revised selected papers

    Energy Technology Data Exchange (ETDEWEB)

    Song, Dawei; Zhang, Peng; Wang, Lei [Aberdeen Univ. (United Kingdom). School of Computing; Melucci, Massimo [Padua Univ., Padova (Italy). Dept. of Information Engineering; Frommholz, Ingo [Bedfordshire Univ. (United Kingdom); Arafat, Sachi (eds.) [Glasgow Univ. (United Kingdom). School of Computing Science

    2011-07-01

    This book constitutes the thoroughly refereed post-conference proceedings of the 5th International Symposium on Quantum Interaction, QI 2011, held in Aberdeen, UK, in June 2011. The 26 revised full papers and 6 revised poster papers, presented together with 1 tutorial and 1 invited talk were carefully reviewed and selected from numerous submissions during two rounds of reviewing and improvement. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, mechanics, social interaction, semantic space and information representation and retrieval. (orig.)

  16. Interaction of radiation with matter

    CERN Document Server

    Nikjoo, Hooshang; Emfietzoglou, Dimitris

    2012-01-01

    Written for students approaching the subject for the first time, this text provides a solid grounding in the physics of the interactions of photons and particles with matter, which is the basis of radiological physics and radiation dosimetry. The authors first present the relevant atomic physics and then describe the interactions, emphasizing practical applications in health/medical physics and radiation biology. They cover such important topics as microdosimetry, interaction of photons with matter, electron energy loss, and dielectric response. Each chapter includes exercises and a summary.

  17. Protein-Protein Interaction Databases

    DEFF Research Database (Denmark)

    Szklarczyk, Damian; Jensen, Lars Juhl

    2015-01-01

    of research are explored. Here we present an overview of the most widely used protein-protein interaction databases and the methods they employ to gather, combine, and predict interactions. We also point out the trade-off between comprehensiveness and accuracy and the main pitfall scientists have to be aware......Years of meticulous curation of scientific literature and increasingly reliable computational predictions have resulted in creation of vast databases of protein interaction data. Over the years, these repositories have become a basic framework in which experiments are analyzed and new directions...

  18. Thyroid hormone receptor interacting protein 13 (TRIP13) AAA-ATPase is a novel mitotic checkpoint-silencing protein.

    Science.gov (United States)

    Wang, Kexi; Sturt-Gillespie, Brianne; Hittle, James C; Macdonald, Dawn; Chan, Gordon K; Yen, Tim J; Liu, Song-Tao

    2014-08-22

    The mitotic checkpoint (or spindle assembly checkpoint) is a fail-safe mechanism to prevent chromosome missegregation by delaying anaphase onset in the presence of defective kinetochore-microtubule attachment. The target of the checkpoint is the E3 ubiquitin ligase anaphase-promoting complex/cyclosome. Once all chromosomes are properly attached and bioriented at the metaphase plate, the checkpoint needs to be silenced. Previously, we and others have reported that TRIP13 AAA-ATPase binds to the mitotic checkpoint-silencing protein p31(comet). Here we show that endogenous TRIP13 localizes to kinetochores. TRIP13 knockdown delays metaphase-to-anaphase transition. The delay is caused by prolonged presence of the effector for the checkpoint, the mitotic checkpoint complex, and its association and inhibition of the anaphase-promoting complex/cyclosome. These results suggest that TRIP13 is a novel mitotic checkpoint-silencing protein. The ATPase activity of TRIP13 is essential for its checkpoint function, and interference with TRIP13 abolished p31(comet)-mediated mitotic checkpoint silencing. TRIP13 overexpression is a hallmark of cancer cells showing chromosomal instability, particularly in certain breast cancers with poor prognosis. We suggest that premature mitotic checkpoint silencing triggered by TRIP13 overexpression may promote cancer development.

  19. Learning an Interactive Segmentation System

    CERN Document Server

    Nickisch, Hannes; Rother, Carsten

    2009-01-01

    Many successful applications of computer vision to image or video manipulation are interactive by nature. However, parameters of such systems are often trained neglecting the user. Traditionally, interactive systems have been treated in the same manner as their fully automatic counterparts. Their performance is evaluated by computing the accuracy of their solutions under some fixed set of user interactions. This paper proposes a new evaluation and learning method which brings the user in the loop. It is based on the use of an active robot user - a simulated model of a human user. We show how this approach can be used to evaluate and learn parameters of state-of-the-art interactive segmentation systems. We also show how simulated user models can be integrated into the popular max-margin method for parameter learning and propose an algorithm to solve the resulting optimisation problem.

  20. Learning Axure RP interactive prototypes

    CERN Document Server

    Krahenbuhl, John Henry

    2015-01-01

    If you are a user experience professional, designer, information architect, or business analyst who wants to gain interactive prototyping skills with Axure, then this book is ideal for you. Some familiarity with Axure is preferred but not essential.

  1. Increasing Positive Interactive Classroom Behavior

    Science.gov (United States)

    Kotcher, Elaine; Doremus, Richard R.

    1973-01-01

    The question examined in this study was as follows: do teachers increase their positive classroom interactive behaviors as a result of training in systematic classroom observation techniques? (Authors/JA)

  2. Rotational ratchets with dipolar interactions.

    Science.gov (United States)

    Jäger, Sebastian; Klapp, Sabine H L

    2012-12-01

    We report results from a computer simulation study on the rotational ratchet effect in systems of magnetic particles interacting via dipolar interactions. The ratchet effect consists of directed rotations of the particles in an oscillating magnetic field, which lacks a net rotating component. Our investigations are based on Brownian dynamics simulations of such many-particle systems. We investigate the influence of both the random and deterministic contributions to the equations of motion on the ratchet effect. As a main result, we show that dipolar interactions can have an enhancing as well as a dampening effect on the ratchet behavior depending on the dipolar coupling strength of the system under consideration. The enhancement is shown to be caused by an increase in the effective field on a particle generated by neighboring magnetic particles, while the dampening is due to restricted rotational motion in the effective field. Moreover, we find a nontrivial influence of the short-range, repulsive interaction between the particles.

  3. Developer's handbook of interactive multimedia

    CERN Document Server

    Phillips, Robin

    2014-01-01

    New technology is being used more and more in education and providers have to be aware of what is on offer and how it can be used. This practical handbook demonstrates how interactive multimedia can be developed for educational application.

  4. Refining Interaction Designs through Simplicity

    Science.gov (United States)

    Muñoz, Pablo; Giner, Pau; Pelechano, Vicente

    With more and more devices in our surroundings, users increasingly-consume applications and digital services which compete for their attention. Therefore, users appreciate simplicity when they interact with them because a less intrusive interaction allows users focus on the task at hand. This work relates an approach based on the concept of simplicity. We propose an iterative interaction design process in which we include a new role. This role is only in charge of providing simplified solutions from original designs. Moreover, we put on practice our proposal in a case study in which we design an application to support mobile workflows. We relate our experience and how new ideas were produced towards the definition of refactored interactions by means of the key of Simplicity.

  5. Walking around to grasp interaction

    DEFF Research Database (Denmark)

    Lykke, Marianne; Jantzen, Christian

    2013-01-01

    with the sound installations. The aim was to gain an understanding of the role of the in-teraction, if interaction makes a difference for the understanding of the sound art. 30 walking interviews were carried out at ZKM, Karlsruhe with a total of 57 museum guests, individuals or groups. During the walk......The paper presents experiences from a study using walk-alongs to provide insight into museum visitors’ experience with interactive features of sound art installations. The overall goal of the study was to learn about the participants’ opinions and feelings about the possibility of interaction...... knowledge of spa-tial conditions, e.g. noise, crowds, darkness provided a profound and shared un-derstanding of e.g. the visitors’ engagement in and dislike of the installations. Another finding concerns group walking that, compared to walking with a sin-gle person, generated a diversified discussion...

  6. Unified Theory of Fundamental Interactions

    Institute of Scientific and Technical Information of China (English)

    WU Ning

    2003-01-01

    Based on local gauge invariance, four different kinds of fundamental interactions in nature are unified in a theory which has SU(3)C( )SU SU(2)L( )U(1)( )s Gravitational Gauge Group gauge symmetry. In this approach,gravitational field, like electromagnetic field, intermediate gauge field, and gluon field, is represented by gauge potential.Four kinds of fundamental interactions are formulated in the similar manner, and therefore can be unified in a direct or semi-direct product group. The model discussed in this paper is a renormalizable quantum model and can be regarded as an extension of the standard model to gravitational interactions, so it can be used to study quantum effects of gravitational interactions.

  7. Vehicle environment interactions - An overview

    Science.gov (United States)

    Raitt, W. J.

    1988-01-01

    The advent of Space Shuttle Orbital operations utilizing science and technology payloads has led to a renewal of interest of vehicle-environmental interactions in low earth orbit. The first science payload on STS-3 showed an interaction on the surface of the Orbiter which, although it had been detected earlier on unmanned spacecraft, quickened interest in the possible impact of this phenomena on future missions. Subsequent flights have yielded data on a wide variety of interaction phenomena resulting from the large size of the Orbiter and its outgassing characteristics. These drivers have given rise to modifications in the neutral gas and plasma environments of the Space Shuttle Orbiter. The physics of the interactions result in the generation of disturbed wave fields, optical emissions and particle distributions in the vicinity of the Orbiter. In this overview, the present observations, suggested interpretations and open questions will be addressed.

  8. Fluctuations and interactions in microemulsions

    Energy Technology Data Exchange (ETDEWEB)

    Menes, R.; Safran, S.A. [Weizmann Institute, Rehovot (Israel); Strey, R. [Max Planck Institute, Gottingen (Germany)

    1995-12-01

    We review the properties of microemulsions as described by an interfacial model which focuses upon the deformations of the surfactant monolayer separating mesoscopic water and oil domains. In some cases, the interfacial shape is well defined, resulting in a globular phase, while in others, the interface is strongly affected by thermal fluctuations, resulting in a random, sponge-like structure. In the globular phase, interactions between globules can result in phase coexistence comparable to those observed in polymeric systems. Recent experiments indicate that these interactions can result in closed-loop coexistence regions in the isothermal, concentration phase diagram. We propose a mechanism for this reentrant phase separation based on the combined effects of a shape transition and attractive interactions. Long cylindrical globules can phase separate at relatively low interglobular attractions. A transformation from elongated globules to compact spherical drops alters the balance between the entropy and the effective interglobule interactions, leading to the remixing of the globular system.

  9. Ultracold fermions with repulsive interactions

    Directory of Open Access Journals (Sweden)

    Ketterle W.

    2013-08-01

    Full Text Available An ultracold Fermi gas with repulsive interaction has been studied. For weak interactions, the atomic gas is metastable, and the interactions were characterized by obtaining the isothermal compressibility from atomic density profiles. For stronger interactions (kFa ≈ 1, rapid conversion into Feshbach molecules is observed. When the conversion rate becomes comparable to the Fermi energy divided by η, the atomic gas cannot reach equilibrium without forming pairs. This precludes the predicted transition to a ferromagnetic state (Stoner transition. The absence of spin fluctuations proves that the gas stays paramagnetic. In free space, a Fermi gas with strong short-range repulsion does not exist because of the rapid coupling to molecular states.

  10. Extended gas in interacting systems

    CERN Document Server

    Combes, F; Paris, Observatoire de

    1997-01-01

    HI observations have revealed large gaseous extensions in interacting and merging systems. The interstellar gas is obviously dragged out in tidal tails during an encounter, and the percentage of HI in the tails increases with the merging stage. However, the opposite is true for the molecular gas, which is observed highly concentrated towards the nuclei of interacting galaxies, amounting to a significant fraction of the dynamical mass. Statistically, there appears to be more gas observed in interacting galaxies than in normal, isolated ones. As N-body simulations show, the gas is driven inwards in the interaction process by the strong gravity torques, before being consumed through star formation in the triggered starbursts. We review here all observations that could bring more knowledge about the state of the gas in the outer parts of galaxies, and about accretion processes. The link with the observations of the Ly$\\alpha$ absorbers at low and high redshifts is discussed.

  11. Database of Interacting Proteins (DIP)

    Data.gov (United States)

    U.S. Department of Health & Human Services — The DIP database catalogs experimentally determined interactions between proteins. It combines information from a variety of sources to create a single, consistent...

  12. Bibliotherapy--The Interactive Process.

    Science.gov (United States)

    Hynes, Arleen McCarty

    1987-01-01

    Discusses the similarities between what librarians call activity bibliotherapy and psychotherapists call poetry therapy, and the need for cooperation between these professions. The interactive aspects of bibliotherapy and the need for professional training in this process are emphasized. (CLB)

  13. Multi-shell effective interactions

    CERN Document Server

    Tsunoda, Naofumi; Hjorth-Jensen, Morten; Otsuka, Takaharu

    2013-01-01

    Background: Effective interactions, either derived from microscopic theories or based on fitting selected properties of nuclei in specific mass regions, are widely used inputs to shell-model studies of nuclei. Until recently, most shell-model calculations have been confined to a single oscillator shell. Recent interest in nuclei away from the stability line, requires however larger shell-model spaces. Since the derivation of microscopic effective interactions has been limited to degenerate model spaces, there are both conceptual and practical limits to present shell-model calculations that utilize such interactions. Purpose: The aim of this work is to present a novel microscopic method to calculate effective interactions for the nuclear shell model. Its main difference from existing theories is that it can be applied not only to degenerate model spaces but also to non-degenerate model spaces. Methods: The formalism is presented in the form of many-body perturbation theory based on the recently developed Exten...

  14. Social Interaction in Learning Networks

    NARCIS (Netherlands)

    Sloep, Peter

    2009-01-01

    The original publication is available from www.springerlink.com. Sloep, P. (2009). Social Interaction in Learning Networks. In R. Koper (Ed.), Learning Network Services for Professional Development (pp 13-15). Berlin, Germany: Springer Verlag.

  15. Interactive Dynamic-System Simulation

    CERN Document Server

    Korn, Granino A

    2010-01-01

    Showing you how to use personal computers for modeling and simulation, Interactive Dynamic-System Simulation, Second Edition provides a practical tutorial on interactive dynamic-system modeling and simulation. It discusses how to effectively simulate dynamical systems, such as aerospace vehicles, power plants, chemical processes, control systems, and physiological systems. Written by a pioneer in simulation, the book introduces dynamic-system models and explains how software for solving differential equations works. After demonstrating real simulation programs with simple examples, the author

  16. Interaction of spatial photorefractive solitons

    DEFF Research Database (Denmark)

    Królikowski, W.; Denz, C.; Stepken, A.

    1998-01-01

    beam or the complete annihilation of some of them, depending on the relative phase of the interacting beams. In the case of mutually incoherent solitons, we show that the photorefractive nonlinearity leads to an anomalous interaction between solitons. Theoretical and experimental results reveal...... that a soliton pair may experience both attractive and repulsive forces; depending on their mutual separation. We also show that strong attraction leads to periodic collision or helical motion of solitons depending on initial conditions....

  17. Interaction improves perception of gloss.

    Science.gov (United States)

    Scheller Lichtenauer, Matthias; Schuetz, Philipp; Zolliker, Peter

    2013-12-18

    Rendering materials on displays becomes ubiquitous in industrial design, architecture, and visualization. Yet the experience of the material from other modes of perception is missing in that representation. This forces observers to rely on visual cues only while judging material properties. In the present study, we compare judgments of rough and glossy surfaces by interacting and passive observers. We investigate whether observers actively exploring rendered stimuli judge properties differently than observers passively watching renderings. Resulting interobserver agreement is significantly higher for interacting observers.

  18. Multiple Interactions in Pythia 8

    CERN Document Server

    Corke, Richard

    2009-01-01

    Modelling multiple partonic interactions in hadronic events is vital for understanding minimum-bias physics, as well as the underlying event of hard processes. A brief overview of the current Pythia 8 multiple interactions (MI) model is given, before looking at two additional effects which can be included in the MI framework. With rescattering, a previously scattered parton is allowed to take part in another subsequent scattering, while with enhanced screening, the effects of varying initial-state fluctuations are modelled.

  19. Action Research and Interactive Research

    DEFF Research Database (Denmark)

    Svensson, lennart; Nielsen, Kurt Aagaard

    2006-01-01

    The authors present trends in Nordic action research. They ask critical questions in the development towards mode 2 and points out alternative roads for a scientific consolidation of action research and interactive research.......The authors present trends in Nordic action research. They ask critical questions in the development towards mode 2 and points out alternative roads for a scientific consolidation of action research and interactive research....

  20. Interactive Video in Medical Education

    OpenAIRE

    Chandrasekhar, Arcot J.; Price, Ronald N.

    1989-01-01

    A variety of attributes have to be taught to a medical student. Various formats of these skills are currently in vogue, namely lectures, small group sessions, preceptorships, etc. The objective of this project is to evaluate the utility of interactive video in medical education. Lessons using interactive video were developed to teach history taking skills, procedural skills, problem solving skills and to acquire knowledge base. Evaluation strategies are being developed to assess which format,...

  1. Parametric Dwarf Spheroidal Tidal Interaction

    CERN Document Server

    Fleck, J J; Fleck, Jean-Julien; Kuhn, Jeff R.

    2003-01-01

    The time dependent tidal interaction of the Local Group Dwarf Spheroidal (dS) Galaxies with the Milky Way (MW) can fundamentally affect their dynamical properties. The model developed here extends earlier numerical descriptions of dS-MW tidal interactions. We explore the dynamical evolution of dS systems in circular or elliptical MW orbits in the framework of a parametric oscillator. An analytic model is developed and compared with more general numerical solutions and N-body simulation experiments.

  2. Interaction webs in arctic ecosystems

    DEFF Research Database (Denmark)

    Schmidt, Niels M.; Hardwick, Bess; Gilg, Olivier;

    2017-01-01

    How species interact modulate their dynamics, their response to environmental change, and ultimately the functioning and stability of entire communities. Work conducted at Zackenberg, Northeast Greenland, has changed our view on how networks of arctic biotic interactions are structured, how they ...... that the combination of long-term, ecosystem-based monitoring, and targeted research projects offers the most fruitful basis for understanding and predicting the future of arctic ecosystems....

  3. Towards Advanced Interaction Design Concepts

    OpenAIRE

    Dijkman, Remco; Dirgahayu, Teduh; Quartel, Dick

    2006-01-01

    In this paper we analyse the interaction mechanisms provided by Web Services technology and by CORBA. Specifically we analyse the request/response, callback, polling and (multicasr) message passing mechanisms. As a result we present Coloured Petri Nets that capture the behaviour of these mechanisms precisely. Based on our analysis we define concepts for representing the Web Services and CORBA interactions in a suitable and platform independent manner. These concepts can be used for platfonn i...

  4. Natural interaction for unmanned systems

    Science.gov (United States)

    Taylor, Glenn; Purman, Ben; Schermerhorn, Paul; Garcia-Sampedro, Guillermo; Lanting, Matt; Quist, Michael; Kawatsu, Chris

    2015-05-01

    Military unmanned systems today are typically controlled by two methods: tele-operation or menu-based, search-andclick interfaces. Both approaches require the operator's constant vigilance: tele-operation requires constant input to drive the vehicle inch by inch; a menu-based interface requires eyes on the screen in order to search through alternatives and select the right menu item. In both cases, operators spend most of their time and attention driving and minding the unmanned systems rather than on being a warfighter. With these approaches, the platform and interface become more of a burden than a benefit. The availability of inexpensive sensor systems in products such as Microsoft Kinect™ or Nintendo Wii™ has resulted in new ways of interacting with computing systems, but new sensors alone are not enough. Developing useful and usable human-system interfaces requires understanding users and interaction in context: not just what new sensors afford in terms of interaction, but how users want to interact with these systems, for what purpose, and how sensors might enable those interactions. Additionally, the system needs to reliably make sense of the user's inputs in context, translate that interpretation into commands for the unmanned system, and give feedback to the user. In this paper, we describe an example natural interface for unmanned systems, called the Smart Interaction Device (SID), which enables natural two-way interaction with unmanned systems including the use of speech, sketch, and gestures. We present a few example applications SID to different types of unmanned systems and different kinds of interactions.

  5. Interactions of amelogenin with phospholipids.

    Science.gov (United States)

    Lokappa, Sowmya Bekshe; Chandrababu, Karthik Balakrishna; Dutta, Kaushik; Perovic, Iva; Evans, John Spencer; Moradian-Oldak, Janet

    2015-02-01

    Amelogenin protein has the potential to interact with other enamel matrix proteins, mineral, and cell surfaces. We investigated the interactions of recombinant amelogenin rP172 with small unilamellar vesicles as model membranes, toward the goal of understanding the mechanisms of amelogenin-cell interactions during amelogenesis. Dynamic light scattering (DLS), fluorescence spectroscopy, circular dichroism (CD), and nuclear magnetic resonance (NMR) were used. In the presence of phospholipid vesicles, a blue shift in the Trp fluorescence emission maxima of rP172 was observed (∼334 nm) and the Trp residues of rP172 were inaccessible to the aqueous quencher acrylamide. DLS studies indicated complexation of rP172 and phospholipids, although the possibility of fusion of phospholipids following amelogenin addition cannot be ruled out. NMR and CD studies revealed a disorder-order transition of rP172 in a model membrane environment. Strong fluorescence resonance energy transfer from Trp in rP172 to DNS-bound-phospholipid was observed, and fluorescence polarization studies indicated that rP172 interacted with the hydrophobic core region of model membranes. Our data suggest that amelogenin has ability to interact with phospholipids and that such interactions may play key roles in enamel biomineralization as well as reported amelogenin signaling activities.

  6. Interactive Dimensioning of Parametric Models

    KAUST Repository

    Kelly, T.

    2015-05-01

    We propose a solution for the dimensioning of parametric and procedural models. Dimensioning has long been a staple of technical drawings, and we present the first solution for interactive dimensioning: A dimension line positioning system that adapts to the view direction, given behavioral properties. After proposing a set of design principles for interactive dimensioning, we describe our solution consisting of the following major components. First, we describe how an author can specify the desired interactive behavior of a dimension line. Second, we propose a novel algorithm to place dimension lines at interactive speeds. Third, we introduce multiple extensions, including chained dimension lines, controls for different parameter types (e.g. discrete choices, angles), and the use of dimension lines for interactive editing. Our results show the use of dimension lines in an interactive parametric modeling environment for architectural, botanical, and mechanical models. © 2015 The Author(s) Computer Graphics Forum © 2015 The Eurographics Association and John Wiley & Sons Ltd. Published by John Wiley & Sons Ltd.

  7. Measurement of interaction between antiprotons

    Science.gov (United States)

    The Star Collaboration; Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Bairathi, V.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de La Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; de Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Klein, S.; Kochenda, L.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, Z. M.; Li, Y.; Li, W.; Li, X.; Li, C.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, R.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, X. M.; Sun, Y.; Sun, X.; Surrow, B.; Svirida, N.; Szelezniak, M. A.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Y.; Wang, Y.; Wang, F.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z. G.; Xie, W.; Xin, K.; Xu, Y. F.; Xu, Q. H.; Xu, H.; Xu, N.; Xu, Z.; Yang, Y.; Yang, C.; Yang, S.; Yang, Y.; Yang, Q.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, Z.; Zhang, J.; Zhang, S.; Zhang, X. P.; Zhang, J.; Zhang, Y.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.

    2015-11-01

    One of the primary goals of nuclear physics is to understand the force between nucleons, which is a necessary step for understanding the structure of nuclei and how nuclei interact with each other. Rutherford discovered the atomic nucleus in 1911, and the large body of knowledge about the nuclear force that has since been acquired was derived from studies made on nucleons or nuclei. Although antinuclei up to antihelium-4 have been discovered and their masses measured, little is known directly about the nuclear force between antinucleons. Here, we study antiproton pair correlations among data collected by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC), where gold ions are collided with a centre-of-mass energy of 200 gigaelectronvolts per nucleon pair. Antiprotons are abundantly produced in such collisions, thus making it feasible to study details of the antiproton-antiproton interaction. By applying a technique similar to Hanbury Brown and Twiss intensity interferometry, we show that the force between two antiprotons is attractive. In addition, we report two key parameters that characterize the corresponding strong interaction: the scattering length and the effective range of the interaction. Our measured parameters are consistent within errors with the corresponding values for proton-proton interactions. Our results provide direct information on the interaction between two antiprotons, one of the simplest systems of antinucleons, and so are fundamental to understanding the structure of more-complex antinuclei and their properties.

  8. Technology Adoption: an Interaction Perspective

    Science.gov (United States)

    Sitorus, Hotna M.; Govindaraju, Rajesri; Wiratmadja, I. I.; Sudirman, Iman

    2016-02-01

    The success of a new technology depends on how well it is accepted by its intended users. Many technologies face the problem of low adoption rate, despite the benefits. An understanding of what makes people accept or reject a new technology can help speed up the adoption rate. This paper presents a framework for technology adoption based on an interactive perspective, resulting from a literature study on technology adoption. In studying technology adoption, it is necessary to consider the interactions among elements involved in the system, for these interactions may generate new characteristics or new relationships. The interactions among elements in a system adoption have not received sufficient consideration in previous studies of technology adoption. Based on the proposed interaction perspective, technology adoption is elaborated by examining interactions among the individual (i.e. the user or prospective user), the technology, the task and the environment. The framework is formulated by adopting several theories, including Perceived Characteristics of Innovating, Diffusion of Innovation Theory, Technology Acceptance Model, Task-Technology Fit and usability theory. The proposed framework is illustrated in the context of mobile banking adoption. It is aimed to offer a better understanding of determinants of technology adoption in various contexts, including technology in manufacturing systems.

  9. Three Baryon Interaction Generated by Determinant Interaction of Quarks

    CERN Document Server

    Ohnishi, Akira; Morita, Kenji

    2016-01-01

    We discuss the three-baryon interaction generated by the determinant interaction of quarks, known as the Kobayashi-Maskawa-'t Hooft (KMT) interaction. The expectation value of the KMT interaction operator is calculated in fully-antisymmetrized quark-cluster model wave functions for one-, two- and three-octet baryon states. The three-baryon potential from the KMT interaction is found to be repulsive for $NN\\Lambda$ and $N\\Lambda\\Lambda$ systems, while it is zero for the $NNN$ system. The strength and range of the three-baryon potential are found to be comparable to those for the $NNN$ three-body potential obtained in lattice QCD simulations. The contribution to the $\\Lambda$ single particle potential in nuclear matter is found to be 0.28 MeV and 0.73 MeV in neutron matter and symmetric nuclear matter at normal nuclear density, respectively. These repulsive forces are not enough to solve the hyperon puzzle, but may be measured in high-precision hyperisotope experiments.

  10. Mixed Interaction Space - Expanding the Interaction Space with Mobile Devices

    DEFF Research Database (Denmark)

    Hansen, Thomas Riisgaard; Eriksson, Eva; Lykke-Olesen, Andreas

    2005-01-01

    In this paper, we describe a new interaction technique for mobile devices named Mixed Interaction Space that uses the camera of the mobile device to track the position, size and rotation of a fixed-point. In this demonstration we will present a system that uses a hand-drawn circle, colored object...... or a person’s face as a fixed-point to determine the location of the device. We use these features as a 4 dimensional input vector to a set of different applications....

  11. A Logic of Interactive Proofs

    CERN Document Server

    Kramer, Simon

    2012-01-01

    We propose a logic of interactive proofs as the first and main step towards an intuitionistic foundation for interactive computation to be obtained via an interactive analog of the G\\"odel-Kolmogorov-Art\\"emov definition of intuitionistic logic as embedded into a classical modal logic of proofs, and of the Curry-Howard isomorphism between intuitionistic proofs and typed programs. Our interactive proofs effectuate a persistent epistemic impact in their intended communities of peer reviewers that consists in the induction of the (propositional) knowledge of their proof goal by means of the (individual) knowledge of the proof with the interpreting reviewer. That is, interactive proofs effectuate a transfer of propositional knowledge---(to-be-)known facts---via the transfer of certain individual knowledge---(to-be-)known proofs---in distributed and multi-agent systems. In other words, we as a community can have the formal common knowledge that a proof is that which if known to one of our peer members would induce...

  12. Field Theory of Fundamental Interactions

    Science.gov (United States)

    Wang, Shouhong; Ma, Tian

    2017-01-01

    First, we present two basic principles, the principle of interaction dynamics (PID) and the principle of representation invariance (PRI). Intuitively, PID takes the variation of the action under energy-momentum conservation constraint. We show that the PID is the requirement of the presence of dark matter and dark energy, the Higgs field and the quark confinement. PRI requires that the SU(N) gauge theory be independent of representations of SU(N). It is clear that PRI is the logic requirement of any gauge theory. With PRI, we demonstrate that the coupling constants for the strong and the weak interactions are the main sources of these two interactions, reminiscent of the electric charge. Second, we emphasize that symmetry principles-the principle of general relativity and the principle of Lorentz invariance and gauge invariance-together with the simplicity of laws of nature, dictate the actions for the four fundamental interactions. Finally, we show that the PID and the PRI, together with the symmetry principles give rise to a unified field model for the fundamental interactions, which is consistent with current experimental observations and offers some new physical predictions. The research is supported in part by the National Science Foundation (NSF) grant DMS-1515024, and by the Office of Naval Research (ONR) grant N00014-15-1-2662.

  13. Motor interference in interactive contexts

    Directory of Open Access Journals (Sweden)

    Eris eChinellato

    2015-06-01

    Full Text Available Action observation and execution share overlapping neural substrates, so that simultaneous activation by observation and execution modulates motor performance. Previous literature on simple prehension tasks has revealed that motor influence can be two-sided: facilitation for observed and performed congruent actions and interference for incongruent actions. But little is known of the specific modulations of motor performance in complex forms of interaction. Is it possible that the very same observed movement can lead either to interference or facilitation effects on a temporally overlapping congruent executed action, depending on the context? To answer this question participants were asked to perform a reach-to-grasp movement adopting a precision grip (PG while: (i observing a fixation cross, (ii observing an actor performing a PG with interactive purposes, (iii observing an actor performing a PG without interactive purposes. In particular, in the interactive condition the actor was shown trying to pour some sugar on a large cup located out of her reach but close to the participant watching the video, thus eliciting in reaction a complementary whole-hand grasp. Notably, fine-grained kinematic analysis for this condition revealed a specific delay in the grasping and reaching components and an increased trajectory deviation despite the observed and executed movement’s congruency. Moreover, early peaks of trajectory deviation seem to indicate that socially relevant stimuli are acknowledged by the motor system very early. These data suggest that interactive contexts can determine a prompt modulation of stimulus–response compatibility effects.

  14. Can molecular cell biology explain chromosome motions?

    Directory of Open Access Journals (Sweden)

    Gagliardi L

    2011-05-01

    Full Text Available Abstract Background Mitotic chromosome motions have recently been correlated with electrostatic forces, but a lingering "molecular cell biology" paradigm persists, proposing binding and release proteins or molecular geometries for force generation. Results Pole-facing kinetochore plates manifest positive charges and interact with negatively charged microtubule ends providing the motive force for poleward chromosome motions by classical electrostatics. This conceptual scheme explains dynamic tracking/coupling of kinetochores to microtubules and the simultaneous depolymerization of kinetochore microtubules as poleward force is generated. Conclusion We question here why cells would prefer complex molecular mechanisms to move chromosomes when direct electrostatic interactions between known bound charge distributions can accomplish the same task much more simply.

  15. Inhomogeneous and interacting vacuum energy

    CERN Document Server

    De-Santiago, Josue; Wang, Yuting

    2012-01-01

    Vacuum energy is a simple model for dark energy driving an accelerated expansion of the universe. If the vacuum energy is inhomogeneous in spacetime then it must be interacting. We present the general equations for a spacetime-dependent vacuum energy in cosmology, including inhomogeneous perturbations. We show how any dark energy cosmology can be described by an interacting vacuum+matter. Different models for the interaction can lead to different behaviour (e.g., sound speed for dark energy perturbations) and hence could be distinguished by cosmological observations. As an example we present the cosmic microwave microwave background anisotropies and the matter power spectrum for two different versions of a generalised Chaplygin gas cosmology.

  16. Quantum simulation with interacting photons

    Science.gov (United States)

    Hartmann, Michael J.

    2016-10-01

    Enhancing optical nonlinearities so that they become appreciable on the single photon level and lead to nonclassical light fields has been a central objective in quantum optics for many years. After this has been achieved in individual micro-cavities representing an effectively zero-dimensional volume, this line of research has shifted its focus towards engineering devices where such strong optical nonlinearities simultaneously occur in extended volumes of multiple nodes of a network. Recent technological progress in several experimental platforms now opens the possibility to employ the systems of strongly interacting photons, these give rise to as quantum simulators. Here we review the recent development and current status of this research direction for theory and experiment. Addressing both, optical photons interacting with atoms and microwave photons in networks of superconducting circuits, we focus on analogue quantum simulations in scenarios where effective photon-photon interactions exceed dissipative processes in the considered platforms.

  17. Quantum Simulation with Interacting Photons

    CERN Document Server

    Hartmann, Michael J

    2016-01-01

    We review the theoretical and experimental developments in recent research on quantum simulators with interacting photons. Enhancing optical nonlinearities so that they become appreciable on the single photon level and lead to nonclassical light fields has been a central objective in quantum optics for many years. After this has been achieved in individual micro-cavities representing an effectively zero-dimensional volume, this line of research has now shifted its focus towards engineering devices where such strong optical nonlinearities simultaneously occur in extended volumes of multiple nodes of a network. Recent technological progress in several experimental platforms now opens the possibility to employ the systems of strongly interacting photons these give rise to as quantum simulators. Here we review the recent development and current status of this research direction for theory and experiment. Addressing both, optical photons interacting with atoms and microwave photons in networks of superconducting c...

  18. Paper mechanisms for sonic interaction

    DEFF Research Database (Denmark)

    Delle Monache, Stefano; Rocchesso, Davide; Qi, Ji

    2012-01-01

    Introducing continuous sonic interaction in augmented pop-up books enhances the expressive and performative qualities of movables, making the whole narrative experience more engaging and personal. The SaMPL Spring School on Sounding Popables explored the specific topic of paper-driven sonic narra...... narratives. Working groups produced several sketches of sonic interactions with movables. The most significant sketches of sounding popables are presented and analyzed.......Introducing continuous sonic interaction in augmented pop-up books enhances the expressive and performative qualities of movables, making the whole narrative experience more engaging and personal. The SaMPL Spring School on Sounding Popables explored the specific topic of paper-driven sonic...

  19. Interactive graphics for geometry modeling

    Science.gov (United States)

    Wozny, M. J.

    1984-01-01

    An interactive vector capability to create geometry and a raster color shaded rendering capability to sample and verify interim geometric design steps through color snapshots is described. The development is outlined of the underlying methodology which facilitates computer aided engineering and design. At present, raster systems cannot match the interactivity and line-drawing capability of refresh vector systems. Consequently, an intermediate step in mechanical design is used to create objects interactively on the vector display and then scan convert the wireframe model to render it as a color shaded object on a raster display. Several algorithms are presented for rendering such objects. Superquadric solid primitive extend the class of primitives normally used in solid modelers.

  20. Spatial experiences and interaction design

    DEFF Research Database (Denmark)

    Dalsgård, Peter

    2006-01-01

    IT is rapidly spreading to non-desktop environments, and is increasingly being used for post-functional purposes. Recent contributions within the field of interaction design have indicated a tight coupling between physico-spatial and experiential issues, both on a technological and on a theoretical...... level. However, interaction design and HCI yet has little to offer designers working with physico-spatial and experiential issues in practical design cases. In this paper, I argue that experiments that explore spatial and experiential aspects are crucial in developing the practice of interaction design....... These  aspects may be brought to the forefront by engaging in, reflecting upon, and reporting from physico-spatial design experiments, and by making spatial and experience-oriented design representations part of the design process. These experiments may be supported by design representations inspired...