WorldWideScience

Sample records for pre-mrna polya tails

  1. Regulation of coronaviral poly(A tail length during infection.

    Directory of Open Access Journals (Sweden)

    Hung-Yi Wu

    Full Text Available The positive-strand coronavirus genome of ~30 kilobase in length and subgenomic (sg mRNAs of shorter lengths, are 5' and 3'-co-terminal by virtue of a common 5'-capped leader and a common 3'-polyadenylated untranslated region. Here, by ligating head-to-tail viral RNAs from bovine coronavirus-infected cells and sequencing across the ligated junctions, it was learned that at the time of peak viral RNA synthesis [6 hours postinfection (hpi] the 3' poly(A tail on genomic and sgmRNAs is ~65 nucleotides (nt in length. Surprisingly, this length was found to vary throughout infection from ~45 nt immediately after virus entry (at 0 to 4 hpi to ~65 nt later on (at 6 h to 9 hpi and from ~65 nt (at 6 h to 9 hpi to ~30 nt (at 120-144 hpi. With the same method, poly(U sequences of the same lengths were simultaneously found on the ligated viral negative-strand RNAs. Functional analyses of poly(A tail length on specific viral RNA species, furthermore, revealed that translation, in vivo, of RNAs with the longer poly(A tail was enhanced over those with the shorter poly(A. Although the mechanisms by which the tail lengths vary is unknown, experimental results together suggest that the length of the poly(A and poly(U tails is regulated. One potential function of regulated poly(A tail length might be that for the coronavirus genome a longer poly(A favors translation. The regulation of coronavirus translation by poly(A tail length resembles that during embryonal development suggesting there may be mechanistic parallels.

  2. The ticking tail: daily oscillations in mRNA poly(A) tail length drive circadian cycles in protein synthesis.

    Science.gov (United States)

    Gotic, Ivana; Schibler, Ueli

    2012-12-15

    In this issue of Genes & Development, Kojima and colleagues (pp. 2724-2736) examined the impact of mRNA poly(A) tail length on circadian gene expression. Their study demonstrates how dynamic changes in transcript poly(A) tail length can lead to rhythmic protein expression, irrespective of whether mRNA accumulation is circadian or constitutive.

  3. Characterization of the Role of Hexamer AGUAAA and Poly(A) Tail in Coronavirus Polyadenylation

    Science.gov (United States)

    Peng, Yu-Hui; Lin, Ching-Houng; Lin, Chao-Nan; Lo, Chen-Yu; Tsai, Tsung-Lin; Wu, Hung-Yi

    2016-01-01

    Similar to eukaryotic mRNA, the positive-strand coronavirus genome of ~30 kilobases is 5’-capped and 3’-polyadenylated. It has been demonstrated that the length of the coronaviral poly(A) tail is not static but regulated during infection; however, little is known regarding the factors involved in coronaviral polyadenylation and its regulation. Here, we show that during infection, the level of coronavirus poly(A) tail lengthening depends on the initial length upon infection and that the minimum length to initiate lengthening may lie between 5 and 9 nucleotides. By mutagenesis analysis, it was found that (i) the hexamer AGUAAA and poly(A) tail are two important elements responsible for synthesis of the coronavirus poly(A) tail and may function in concert to accomplish polyadenylation and (ii) the function of the hexamer AGUAAA in coronaviral polyadenylation is position dependent. Based on these findings, we propose a process for how the coronaviral poly(A) tail is synthesized and undergoes variation. Our results provide the first genetic evidence to gain insight into coronaviral polyadenylation. PMID:27760233

  4. Validation of artificial microRNA expression by poly(A) tailing-based RT-PCR

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Rui Shi, Chenmin Yang, Ronald Sederoff & Vincent Chiang ### Abstract Here we describe a protocol for validating expression of artificial microRNAs (amiRNAs) by poly(A) tailing-based RT-PCR. Total RNAs, including amiRNA, are poly(A) tailed using E.coli. poly(A) polymerase. Poly(A) tailed amiRNA can be converted into cDNA along with mRNAs in a reverse transcription reaction primed by a standard poly(T) anchor adaptor. AmiRNA can then be amplified and quantitated by real-tim...

  5. Rrp6p controls mRNA poly(a) tail length and its decoration with poly(a) binding proteins

    DEFF Research Database (Denmark)

    Schmid, Manfred; Poulsen, Mathias Bach; Olszewski, Pawel;

    2012-01-01

    Poly(A) (pA) tail binding proteins (PABPs) control mRNA polyadenylation, stability, and translation. In a purified system, S. cerevisiae PABPs, Pab1p and Nab2p, are individually sufficient to provide normal pA tail length. However, it is unknown how this occurs in more complex environments. Here ...

  6. Removal of polyA tails from full-length cDNA libraries for high-efficiency sequencing.

    Science.gov (United States)

    Shibata, Y; Carninci, P; Sato, K; Hayatsu, N; Shiraki, T; Ishii, Y; Arakawa, T; Hara, A; Ohsato, N; Izawa, M; Aizawa, K; Itoh, M; Shibata, K; Shinagawa, A; Kawai, J; Ota, Y; Kikuchi, S; Kishimoto, N; Muramatsu, M; Hayashizaki, Y

    2001-11-01

    We have developed a method to overcome sequencing problems caused by the presence of homopolymer stretches, such as polyA/T, in cDNA libraries. PolyA tails are shortened by cleaving before cDNA cloning with type IIS restriction enzymes, such as GsuI, placed next to the oligo-dT used to prime the polyA tails of mRNAs. We constructed four rice Cap-Trapper-selected, full-length normalized cDNA libraries, of which the average residual polyA tail was 4 bases or shorter in most of the clones analyzed Because of the removal of homopolymeric stretches, libraries prepared with this method can be used for direct sequencing and transcriptional sequencing without the slippage observed for libraries prepared with currently available methods, thus improving sequencing accuracy, operations, and throughput.

  7. Poly(A) Tail Recognition by a Viral RNA Element Through Assembly of a Triple Helix

    Energy Technology Data Exchange (ETDEWEB)

    M Mitton-Fry; S DeGregorio; J Wang; T Steitz; J Steitz

    2011-12-31

    Kaposi's sarcoma-associated herpesvirus produces a highly abundant, nuclear noncoding RNA, polyadenylated nuclear (PAN) RNA, which contains an element that prevents its decay. The 79-nucleotide expression and nuclear retention element (ENE) was proposed to adopt a secondary structure like that of a box H/ACA small nucleolar RNA (snoRNA), with a U-rich internal loop that hybridizes to and protects the PAN RNA poly(A) tail. The crystal structure of a complex between the 40-nucleotide ENE core and oligo(A){sub 9} RNA at 2.5 angstrom resolution reveals that unlike snoRNAs, the U-rich loop of the ENE engages its target through formation of a major-groove triple helix. A-minor interactions extend the binding interface. Deadenylation assays confirm the functional importance of the triple helix. Thus, the ENE acts as an intramolecular RNA clamp, sequestering the PAN poly(A) tail and preventing the initiation of RNA decay.

  8. A Simple Decision Rule for Recognition of Poly(A) Tail Signal Motifs in Human Genome

    KAUST Repository

    AbouEisha, Hassan M.

    2015-05-12

    Background is the numerous attempts were made to predict motifs in genomic sequences that correspond to poly (A) tail signals. Vast portion of this effort has been directed to a plethora of nonlinear classification methods. Even when such approaches yield good discriminant results, identifying dominant features of regulatory mechanisms nevertheless remains a challenge. In this work, we look at decision rules that may help identifying such features. Findings are we present a simple decision rule for classification of candidate poly (A) tail signal motifs in human genomic sequence obtained by evaluating features during the construction of gradient boosted trees. We found that values of a single feature based on the frequency of adenine in the genomic sequence surrounding candidate signal and the number of consecutive adenine molecules in a well-defined region immediately following the motif displays good discriminative potential in classification of poly (A) tail motifs for samples covered by the rule. Conclusions is the resulting simple rule can be used as an efficient filter in construction of more complex poly(A) tail motifs classification algorithms.

  9. A triple helix stabilizes the 3' ends of long noncoding RNAs that lack poly(A) tails.

    Science.gov (United States)

    Wilusz, Jeremy E; JnBaptiste, Courtney K; Lu, Laura Y; Kuhn, Claus-D; Joshua-Tor, Leemor; Sharp, Phillip A

    2012-11-01

    The MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) locus is misregulated in many human cancers and produces an abundant long nuclear-retained noncoding RNA. Despite being transcribed by RNA polymerase II, the 3' end of MALAT1 is produced not by canonical cleavage/polyadenylation but instead by recognition and cleavage of a tRNA-like structure by RNase P. Mature MALAT1 thus lacks a poly(A) tail yet is expressed at a level higher than many protein-coding genes in vivo. Here we show that the 3' ends of MALAT1 and the MEN β long noncoding RNAs are protected from 3'-5' exonucleases by highly conserved triple helical structures. Surprisingly, when these structures are placed downstream from an ORF, the transcript is efficiently translated in vivo despite the lack of a poly(A) tail. The triple helix therefore also functions as a translational enhancer, and mutations in this region separate this translation activity from simple effects on RNA stability or transport. We further found that a transcript ending in a triple helix is efficiently repressed by microRNAs in vivo, arguing against a major role for the poly(A) tail in microRNA-mediated silencing. These results provide new insights into how transcripts that lack poly(A) tails are stabilized and regulated and suggest that RNA triple-helical structures likely have key regulatory functions in vivo.

  10. Measurement of mRNA Poly(A) Tail Lengths in Drosophila Female Germ Cells and Germ-Line Stem Cells.

    Science.gov (United States)

    Chartier, Aymeric; Joly, Willy; Simonelig, Martine

    2017-01-01

    mRNA regulation by poly(A) tail length variations plays an important role in many developmental processes. Recent advances have shown that, in particular, deadenylation (the shortening of mRNA poly(A) tails) is essential for germ-line stem cell biology in the Drosophila ovary. Therefore, a rapid and accurate method to analyze poly(A) tail lengths of specific mRNAs in this tissue is valuable. Several methods of poly(A) test (PAT) assays have been reported to measure mRNA poly(A) tail lengths in vivo. Here, we describe two of these methods (PAT and ePAT) that we have adapted for Drosophila ovarian germ cells and germ-line stem cells.

  11. Mitochondrial dysfunction reveals the role of mRNA poly(A tail regulation in oculopharyngeal muscular dystrophy pathogenesis.

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    Aymeric Chartier

    2015-03-01

    Full Text Available Oculopharyngeal muscular dystrophy (OPMD, a late-onset disorder characterized by progressive degeneration of specific muscles, results from the extension of a polyalanine tract in poly(A binding protein nuclear 1 (PABPN1. While the roles of PABPN1 in nuclear polyadenylation and regulation of alternative poly(A site choice are established, the molecular mechanisms behind OPMD remain undetermined. Here, we show, using Drosophila and mouse models, that OPMD pathogenesis depends on affected poly(A tail lengths of specific mRNAs. We identify a set of mRNAs encoding mitochondrial proteins that are down-regulated starting at the earliest stages of OPMD progression. The down-regulation of these mRNAs correlates with their shortened poly(A tails and partial rescue of their levels when deadenylation is genetically reduced improves muscle function. Genetic analysis of candidate genes encoding RNA binding proteins using the Drosophila OPMD model uncovers a potential role of a number of them. We focus on the deadenylation regulator Smaug and show that it is expressed in adult muscles and specifically binds to the down-regulated mRNAs. In addition, the first step of the cleavage and polyadenylation reaction, mRNA cleavage, is affected in muscles expressing alanine-expanded PABPN1. We propose that impaired cleavage during nuclear cleavage/polyadenylation is an early defect in OPMD. This defect followed by active deadenylation of specific mRNAs, involving Smaug and the CCR4-NOT deadenylation complex, leads to their destabilization and mitochondrial dysfunction. These results broaden our understanding of the role of mRNA regulation in pathologies and might help to understand the molecular mechanisms underlying neurodegenerative disorders that involve mitochondrial dysfunction.

  12. Mitochondrial dysfunction reveals the role of mRNA poly(A) tail regulation in oculopharyngeal muscular dystrophy pathogenesis.

    Science.gov (United States)

    Chartier, Aymeric; Klein, Pierre; Pierson, Stéphanie; Barbezier, Nicolas; Gidaro, Teresa; Casas, François; Carberry, Steven; Dowling, Paul; Maynadier, Laurie; Bellec, Maëlle; Oloko, Martine; Jardel, Claude; Moritz, Bodo; Dickson, George; Mouly, Vincent; Ohlendieck, Kay; Butler-Browne, Gillian; Trollet, Capucine; Simonelig, Martine

    2015-03-01

    Oculopharyngeal muscular dystrophy (OPMD), a late-onset disorder characterized by progressive degeneration of specific muscles, results from the extension of a polyalanine tract in poly(A) binding protein nuclear 1 (PABPN1). While the roles of PABPN1 in nuclear polyadenylation and regulation of alternative poly(A) site choice are established, the molecular mechanisms behind OPMD remain undetermined. Here, we show, using Drosophila and mouse models, that OPMD pathogenesis depends on affected poly(A) tail lengths of specific mRNAs. We identify a set of mRNAs encoding mitochondrial proteins that are down-regulated starting at the earliest stages of OPMD progression. The down-regulation of these mRNAs correlates with their shortened poly(A) tails and partial rescue of their levels when deadenylation is genetically reduced improves muscle function. Genetic analysis of candidate genes encoding RNA binding proteins using the Drosophila OPMD model uncovers a potential role of a number of them. We focus on the deadenylation regulator Smaug and show that it is expressed in adult muscles and specifically binds to the down-regulated mRNAs. In addition, the first step of the cleavage and polyadenylation reaction, mRNA cleavage, is affected in muscles expressing alanine-expanded PABPN1. We propose that impaired cleavage during nuclear cleavage/polyadenylation is an early defect in OPMD. This defect followed by active deadenylation of specific mRNAs, involving Smaug and the CCR4-NOT deadenylation complex, leads to their destabilization and mitochondrial dysfunction. These results broaden our understanding of the role of mRNA regulation in pathologies and might help to understand the molecular mechanisms underlying neurodegenerative disorders that involve mitochondrial dysfunction.

  13. Pre- and postovulatory aging of murine oocytes affect the transcript level and poly(A tail length of maternal effect genes.

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    Debora Dankert

    Full Text Available Maternal effect genes code for oocyte proteins that are important for early embryogenesis. Transcription in oocytes does not take place from the onset of meiotic progression until zygotic genome activation. During this period, protein levels are regulated posttranscriptionally, for example by poly(A tail length. Posttranscriptional regulation may be impaired in preovulatory and postovulatory aged oocytes, caused by delayed ovulation or delayed fertilization, respectively, and may lead to developmental defects. We investigated transcript levels and poly(A tail length of ten maternal effect genes in in vivo- and in vitro- (follicle culture grown oocytes after pre- and postovulatory aging. Quantitative RT-PCR was performed using random hexamer-primed cDNA to determine total transcript levels and oligo(dT16-primed cDNA to analyze poly(A tail length. Transcript levels of in vivo preovulatory-aged oocytes remained stable except for decreases in Brg1 and Tet3. Most genes investigated showed a tendency towards increased poly(A content. Polyadenylation of in vitro preovulatory-aged oocytes was also increased, along with transcript level declines of Trim28, Nlrp2, Nlrp14 and Zar1. In contrast to preovulatory aging, postovulatory aging of in vivo- and in vitro-grown oocytes led to a shortening of poly(A tails. Postovulatory aging of in vivo-grown oocytes resulted in deadenylation of Nlrp5 after 12 h, and deadenylation of 4 further genes (Tet3, Trim28, Dnmt1, Oct4 after 24 h. Similarly, transcripts of in vitro-grown oocytes were deadenylated after 12 h of postovulatory aging (Tet3, Trim28, Zfp57, Dnmt1, Nlrp5, Zar1. This impact of aging on poly(A tail length may affect the timed translation of maternal effect gene transcripts and thereby contribute to developmental defects.

  14. The PolyA tail length of yeast histone mRNAs varies during the cell cycle and is influenced by Sen1p and Rrp6p.

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    Beggs, Suzanne; James, Tharappel C; Bond, Ursula

    2012-03-01

    Yeast histone mRNAs are polyadenylated, yet factors such as Rrp6p and Trf4p, required for the 3'-end processing of non-polyadenylated RNAs, contribute to the cell cycle regulation of these transcripts. Here, we investigated the role of other known 3'-end processing/transcription termination factors of non-polyadenylated RNA in the biogenesis of histone mRNAs, specifically the Nab3p/Nrd1p/Sen1p complex. We also re-evaluated the polyadenylation status of these mRNAs during the cell cycle. Our analysis reveals that yeast histone mRNAs have shorter than average PolyA tails and the length of the PolyA tail varies during the cell cycle; S-phase histone mRNAs possess very short PolyA tails while in G1, the tail length is relatively longer. Inactivation of either Sen1p or Rrp6p leads to a decrease in the PolyA tail length of histone mRNAs. Our data also show that Sen1p contributes to 3'-end processing of histone primary transcripts. Thus, histone mRNAs are distinct from the general pool of yeast mRNAs and 3'-end processing and polyadenylation contribute to the cell cycle regulation of these transcripts.

  15. A comparative study of microbial diversity and community structure in marine sediments using poly(A tailing and reverse transcription PCR

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    Tatsuhiko eHoshino

    2013-06-01

    Full Text Available To obtain a better understanding of metabolically active microbial communities, we tested a molecular ecological approach using poly(A tailing of environmental 16S rRNA, followed by full-length complementary DNA (cDNA synthesis and sequencing to eliminate potential biases caused by mismatching of PCR primer sequences. The RNA pool tested was extracted from marine sediments of the Yonaguni Knoll IV hydrothermal field in the southern Okinawa Trough. The sequences obtained using the ploy(A tailing method were compared statistically and phylogenetically with those obtained using conventional reverse transcription-polymerase chain reaction (RT-PCR with published domain-specific primers. Both methods indicated that Deltaproteobacteria are predominant in sediment (>85% of the total sequence read. The poly(A tailing method indicated that Desulfobacterales were the predominant deltaproteobacteria, while most of the sequences in libraries constructed using RT-PCR were derived from Desulfuromonadales. This discrepancy may have been due to low coverage of Desulfobacterales by the primers used. A comparison of library diversity indices indicated that the poly(A tailing method retrieves more phylogenetically diverse sequences from the environment. The four archaeal 16S rRNA sequences that were obtained using the poly(A tailing method formed deeply branching lineages that were related to Candidatus Parvarchaeum and the Ancient Archaeal Group. These results clearly demonstrate that poly(A tailing followed by cDNA sequencing is a powerful and less biased molecular ecological approach for the study of metabolically active microbial communities.

  16. The 3′ Untranslated Region of the Andes Hantavirus Small mRNA Functionally Replaces the Poly(A) Tail and Stimulates Cap-Dependent Translation Initiation from the Viral mRNA ▿

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    Vera-Otarola, Jorge; Soto-Rifo, Ricardo; Ricci, Emiliano P.; Ohlmann, Théophile; Darlix, Jean-Luc; López-Lastra, Marcelo

    2010-01-01

    In the process of translation of eukaryotic mRNAs, the 5′ cap and the 3′ poly(A) tail interact synergistically to stimulate protein synthesis. Unlike its cellular counterparts, the small mRNA (SmRNA) of Andes hantavirus (ANDV), a member of the Bunyaviridae, lacks a 3′ poly(A) tail. Here we report that the 3′ untranslated region (3′UTR) of the ANDV SmRNA functionally replaces a poly(A) tail and synergistically stimulates cap-dependent translation initiation from the viral mRNA. Stimulation of translation by the 3′UTR of the ANDV SmRNA was found to be independent of viral proteins and of host poly(A)-binding protein. PMID:20660206

  17. Viral uncoating is directional: exit of the genomic RNA in a common cold virus starts with the poly-(A tail at the 3'-end.

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    Shushan Harutyunyan

    Full Text Available Upon infection, many RNA viruses reorganize their capsid for release of the genome into the host cell cytosol for replication. Often, this process is triggered by receptor binding and/or by the acidic environment in endosomes. In the genus Enterovirus, which includes more than 150 human rhinovirus (HRV serotypes causing the common cold, there is persuasive evidence that the viral RNA exits single-stranded through channels formed in the protein shell. We have determined the time-dependent emergence of the RNA ends from HRV2 on incubation of virions at 56°C using hybridization with specific oligonucleotides and detection by fluorescence correlation spectroscopy. We report that psoralen UV crosslinking prevents complete RNA release, allowing for identification of the sequences remaining inside the capsid. We also present the structure of uncoating intermediates in which parts of the RNA are condensed and take the form of a rod that is directed roughly towards a two-fold icosahedral axis, the presumed RNA exit point. Taken together, in contrast to schemes frequently depicted in textbooks and reviews, our findings demonstrate that exit of the RNA starts from the 3'-end. This suggests that packaging also occurs in an ordered manner resulting in the 3'-poly-(A tail becoming located close to a position of pore formation during conversion of the virion into a subviral particle. This directional genome release may be common to many icosahedral non-enveloped single-stranded RNA viruses.

  18. Viral uncoating is directional: exit of the genomic RNA in a common cold virus starts with the poly-(A) tail at the 3'-end.

    Science.gov (United States)

    Harutyunyan, Shushan; Kumar, Mohit; Sedivy, Arthur; Subirats, Xavier; Kowalski, Heinrich; Köhler, Gottfried; Blaas, Dieter

    2013-01-01

    Upon infection, many RNA viruses reorganize their capsid for release of the genome into the host cell cytosol for replication. Often, this process is triggered by receptor binding and/or by the acidic environment in endosomes. In the genus Enterovirus, which includes more than 150 human rhinovirus (HRV) serotypes causing the common cold, there is persuasive evidence that the viral RNA exits single-stranded through channels formed in the protein shell. We have determined the time-dependent emergence of the RNA ends from HRV2 on incubation of virions at 56°C using hybridization with specific oligonucleotides and detection by fluorescence correlation spectroscopy. We report that psoralen UV crosslinking prevents complete RNA release, allowing for identification of the sequences remaining inside the capsid. We also present the structure of uncoating intermediates in which parts of the RNA are condensed and take the form of a rod that is directed roughly towards a two-fold icosahedral axis, the presumed RNA exit point. Taken together, in contrast to schemes frequently depicted in textbooks and reviews, our findings demonstrate that exit of the RNA starts from the 3'-end. This suggests that packaging also occurs in an ordered manner resulting in the 3'-poly-(A) tail becoming located close to a position of pore formation during conversion of the virion into a subviral particle. This directional genome release may be common to many icosahedral non-enveloped single-stranded RNA viruses.

  19. Secondary structures involving the poly(A tail and other 3’ sequences are major determinants of mRNA isoform stability in yeast

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    Zarmik Moqtaderi

    2014-04-01

    Full Text Available In Saccharomyces cerevisiae, previous measurements of mRNA stabilities have been determined on a per-gene basis. We and others have recently shown that yeast genes give rise to a highly heterogeneous population of mRNAs due to extensive alternative 3’ end formation. Typical genes can have fifty or more distinct mRNA isoforms with 3’ endpoints differing by as little as one and as many as hundreds of nucleotides. In our recent paper [Geisberg et al. Cell (2014 156: 812-824] we measured half-lives of individual mRNA isoforms in Saccharomyces cerevisiae by using the anchor away method for the rapid removal of Rpb1, the largest subunit of RNA Polymerase II, from the nucleus, followed by direct RNA sequencing of the cellular mRNA population over time. Combining these two methods allowed us to determine half-lives for more than 20,000 individual mRNA isoforms originating from nearly 5000 yeast genes. We discovered that different 3’ mRNA isoforms arising from the same gene can have widely different stabilities, and that such half-life variability across mRNA isoforms from a single gene is highly prevalent in yeast cells. Determining half-lives for many different mRNA isoforms from the same genes allowed us to identify hundreds of RNA sequence elements involved in the stabilization and destabilization of individual isoforms. In many cases, the poly(A tail is likely to participate in the formation of stability - enhancing secondary structures at mRNA 3’ ends. Our results point to an important role for mRNA structure at 3’ termini in governing transcript stability, likely by reducing the interaction of the mRNA with the degradation apparatus.

  20. Development of Nonaggregating Poly-A Tailed Immunostimulatory A/D Type CpG Oligodeoxynucleotides Applicable for Clinical Use

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    Taiki Aoshi

    2015-01-01

    Full Text Available Immunostimulatory CpG ODNs have been developed and utilized as TLR9-dependent innate immune activators and vaccine adjuvants. Four different types of immunostimulatory CpG ODNs (A/D, B/K, C, and P type have been reported. A/D type ODNs are characterized by high IFN-α production but intrinsically form aggregates, hindering its good manufacturing practice grade preparation. In this study, we developed several D35-derived ODNs (a commonly used A/D type ODN, which were modified with the addition of a phosphorothioate polynucleotide tail (such as dAs40, and examined their physical properties, solubility in saline, immunostimulatory activity on human PBMCs, and vaccine adjuvant potential in monkeys. We found that two modified ODNs including D35-dAs40 and D35core-dAs40 were immunostimulatory, similar to original D35 in human PBMCs, resulting in high IFN-α secretion in a dose-dependent manner. Physical property analysis by dynamic light scattering revealed that both D35-dAs40 and D35core-dAs40 did not form aggregates in saline, which is currently impossible for the original D35. Furthermore, D35-dAs40 and D35core-dAs40 worked as better vaccine adjuvant in monkeys. These results suggested that D35-dAs40 and D35core-dAs40 are two promising prototypes of nonaggregating A/D type ODN with advantages of ease of drug preparation for clinical applications as vaccine adjuvants or IFN-α inducing immunomodifiers.

  1. Rubbery Polya Tree.

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    Nieto-Barajas, Luis E; Müller, Peter

    2012-03-01

    Polya trees (PT) are random probability measures which can assign probability 1 to the set of continuous distributions for certain specifications of the hyperparameters. This feature distinguishes the PT from the popular Dirichlet process (DP) model which assigns probability 1 to the set of discrete distributions. However, the PT is not nearly as widely used as the DP prior. Probably the main reason is an awkward dependence of posterior inference on the choice of the partitioning subsets in the definition of the PT. We propose a generalization of the PT prior that mitigates this undesirable dependence on the partition structure, by allowing the branching probabilities to be dependent within the same level. The proposed new process is not a PT anymore. However, it is still a tail-free process and many of the prior properties remain the same as those for the PT.

  2. Dragon polya spotter: Predictor of poly(A) motifs within human genomic DNA sequences

    KAUST Repository

    Kalkatawi, Manal Matoq Saeed

    2011-11-15

    Motivation: Recognition of poly(A) signals in mRNA is relatively straightforward due to the presence of easily recognizable polyadenylic acid tail. However, the task of identifying poly(A) motifs in the primary genomic DNA sequence that correspond to poly(A) signals in mRNA is a far more challenging problem. Recognition of poly(A) signals is important for better gene annotation and understanding of the gene regulation mechanisms. In this work, we present one such poly(A) motif prediction method based on properties of human genomic DNA sequence surrounding a poly(A) motif. These properties include thermodynamic, physico-chemical and statistical characteristics. For predictions, we developed Artificial Neural Network and Random Forest models. These models are trained to recognize 12 most common poly(A) motifs in human DNA. Our predictors are available as a free web-based tool accessible at http://cbrc.kaust.edu.sa/dps. Compared with other reported predictors, our models achieve higher sensitivity and specificity and furthermore provide a consistent level of accuracy for 12 poly(A) motif variants. The Author(s) 2011. Published by Oxford University Press. All rights reserved.

  3. LARP1 specifically recognizes the 3' terminus of poly(A) mRNA.

    Science.gov (United States)

    Aoki, Kazuma; Adachi, Shungo; Homoto, Masae; Kusano, Hideo; Koike, Katsuyuki; Natsume, Tohru

    2013-07-11

    A poly(A) tail functions in mRNA turnover and in facilitating translation as a ribonucleoprotein complex with poly(A) binding proteins (PABPs). However, factors that associate with the poly(A) tail other than PABPs have not been described. Using proteomics, we identified candidate proteins that interact to the 3' terminus of the poly(A) tail. Among these proteins, we focused on La motif-related protein 1 (LARP1) and found that LARP1 specifically recognizes the 3' termini of normal poly(A) tails. We also reveal that LARP1 stabilizes multiple mRNAs carrying 5' terminal oligopyrimidine tract (5'TOP). Our findings suggest that LARP1 may be involved in the post-transcriptional regulation of gene expression, at least in several 5'TOP mRNAs, through the binding to 3' terminus of the poly(A) tail.

  4. Positive and Negative Regulation of Poly(A) Nuclease

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    Mangus, David A.; Evans, Matthew C.; Agrin, Nathan S.; Smith, Mandy; Gongidi, Preetam; Jacobson, Allan

    2004-01-01

    PAN, a yeast poly(A) nuclease, plays an important nuclear role in the posttranscriptional maturation of mRNA poly(A) tails. The activity of this enzyme is dependent on its Pan2p and Pan3p subunits, as well as the presence of poly(A)-binding protein (Pab1p). We have identified and characterized the associated network of factors controlling the maturation of mRNA poly(A) tails in yeast and defined its relevant protein-protein interactions. Pan3p, a positive regulator of PAN activity, interacts with Pab1p, thus providing substrate specificity for this nuclease. Pab1p also regulates poly(A) tail trimming by interacting with Pbp1p, a factor that appears to negatively regulate PAN. Pan3p and Pbp1p both interact with themselves and with the C terminus of Pab1p. However, the domains required for Pan3p and Pbp1p binding on Pab1p are distinct. Single amino acid changes that disrupt Pan3p interaction with Pab1p have been identified and define a binding pocket in helices 2 and 3 of Pab1p's carboxy terminus. The importance of these amino acids for Pab1p-Pan3p interaction, and poly(A) tail regulation, is underscored by experiments demonstrating that strains harboring substitutions in these residues accumulate mRNAs with long poly(A) tails in vivo. PMID:15169912

  5. Site-specific terminal and internal labeling of RNA by poly(A) polymerase tailing and copper-catalyzed or copper-free strain-promoted click chemistry.

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    Winz, Marie-Luise; Samanta, Ayan; Benzinger, Dirk; Jäschke, Andres

    2012-05-01

    The modification of RNA with fluorophores, affinity tags and reactive moieties is of enormous utility for studying RNA localization, structure and dynamics as well as diverse biological phenomena involving RNA as an interacting partner. Here we report a labeling approach in which the RNA of interest--of either synthetic or biological origin--is modified at its 3'-end by a poly(A) polymerase with an azido-derivatized nucleotide. The azide is later on conjugated via copper-catalyzed or strain-promoted azide-alkyne click reaction. Under optimized conditions, a single modified nucleotide of choice (A, C, G, U) containing an azide at the 2'-position can be incorporated site-specifically. We have identified ligases that tolerate the presence of a 2'-azido group at the ligation site. This azide is subsequently reacted with a fluorophore alkyne. With this stepwise approach, we are able to achieve site-specific, internal backbone-labeling of de novo synthesized RNA molecules.

  6. Site-specific terminal and internal labeling of RNA by poly(A) polymerase tailing and copper-catalyzed or copper-free strain-promoted click chemistry

    Science.gov (United States)

    Winz, Marie-Luise; Samanta, Ayan; Benzinger, Dirk; Jäschke, Andres

    2012-01-01

    The modification of RNA with fluorophores, affinity tags and reactive moieties is of enormous utility for studying RNA localization, structure and dynamics as well as diverse biological phenomena involving RNA as an interacting partner. Here we report a labeling approach in which the RNA of interest—of either synthetic or biological origin—is modified at its 3′-end by a poly(A) polymerase with an azido-derivatized nucleotide. The azide is later on conjugated via copper-catalyzed or strain-promoted azide–alkyne click reaction. Under optimized conditions, a single modified nucleotide of choice (A, C, G, U) containing an azide at the 2′-position can be incorporated site-specifically. We have identified ligases that tolerate the presence of a 2′-azido group at the ligation site. This azide is subsequently reacted with a fluorophore alkyne. With this stepwise approach, we are able to achieve site-specific, internal backbone-labeling of de novo synthesized RNA molecules. PMID:22344697

  7. Polya Theory for Orbiquotient Sets

    OpenAIRE

    Blandin, Hector; Diaz, Rafael

    2005-01-01

    Replacing the usual notion of quotient sets by the notion of orbiquotient sets we obtain a generalization of P\\'olya theory. The key ingredient of our extended theory is the definition of the orbicycle index polynomial which we compute in several examples. We apply our theory to the study of orbicycles on orbiquotient sets. Keywords: Orbifolds, P\\'olya Theory, Partition Lattice.

  8. The cytoplasmic poly(A) polymerases GLD-2 and GLD-4 promote general gene expression via distinct mechanisms

    OpenAIRE

    Nousch, M.; Yeroslaviz, A.; Habermann, B; Eckmann, C

    2014-01-01

    Post-transcriptional gene regulation mechanisms decide on cellular mRNA activities. Essential gatekeepers of post-transcriptional mRNA regulation are broadly conserved mRNA-modifying enzymes, such as cytoplasmic poly(A) polymerases (cytoPAPs). Although these non-canonical nucleotidyltransferases efficiently elongate mRNA poly(A) tails in artificial tethering assays, we still know little about their global impact on poly(A) metabolism and their individual molecular roles in promoting protein p...

  9. Structural biology of poly(A) site definition.

    Science.gov (United States)

    Yang, Qin; Doublié, Sylvie

    2011-01-01

    3' processing is an essential step in the maturation of all messenger RNAs (mRNAs) and is a tightly coupled two-step reaction: endonucleolytic cleavage at the poly(A) site is followed by the addition of a poly(A) tail, except for metazoan histone mRNAs, which are cleaved but not polyadenylated. The recognition of a poly(A) site is coordinated by the sequence elements in the mRNA 3' UTR and associated protein factors. In mammalian cells, three well-studied sequence elements, UGUA, AAUAAA, and GU-rich, are recognized by three multisubunit factors: cleavage factor I(m) (CFI(m) ), cleavage and polyadenylation specificity factor (CPSF), and cleavage stimulation factor (CstF), respectively. In the yeast Saccharomyces cerevisiae, UA repeats and A-rich sequence elements are recognized by Hrp1p and cleavage factor IA. Structural studies of protein-RNA complexes have helped decipher the mechanisms underlying sequence recognition and shed light on the role of protein factors in poly(A) site selection and 3' processing machinery assembly. In this review we focus on the interactions between the mRNA cis-elements and the protein factors (CFI(m) , CPSF, CstF, and homologous factors from yeast and other eukaryotes) that define the poly(A) site. WIREs RNA 2011 2 732-747 DOI: 10.1002/wrna.88 For further resources related to this article, please visit the WIREs website. Copyright © 2011 John Wiley & Sons, Ltd.

  10. A poly(A) binding protein-specific sequence motif: MRTENGKSKGFGFVC binding to mRNA poly(A) and polynucleotides and its role on mRNA translation.

    Science.gov (United States)

    Rubin, H N; Halim, M N; Leavis, P C

    1994-06-01

    A consensus sequence (GKSKGFGFV) was recognized in all the sequenced poly(A) binding proteins. We synthesized a 15-amino acid peptide (corresponding to 354-368 in the yeast poly(A) binding protein) which includes the consensus sequence to test its binding affinity to different nucleotides, polynucleotides and mRNA with or without a poly(A) tail. Biochemical and biophysical studies revealed that the 15-amino acid peptide has a strong binding affinity to poly(A) alone or poly(A) attached at the 3' end of mRNA. Circular dichroism spectroscopy demonstrated that the secondary structure of the 15-mer is consistent with that expected based on the structure of the native RNP domain. Furthermore, among the various mononucleotides performed in the present studies, ATP was preferentially found to bind to the 15-mer. To further examine the biological significance of the binding of the 15-mer to the poly(A) tail of mRNA, in vitro translation of the mRNA poly(A)+ in the presence of the 15-mer drastically increased globin synthesis by almost 2-fold, while translation of the deadenylated mRNA in the presence of the 15-mer almost did not alter the rate of incorporation of radiolabeled leucine into globin.

  11. On Polya-Friedman random walks

    Energy Technology Data Exchange (ETDEWEB)

    Huillet, Thierry [Laboratoire de Physique Theorique et Modelisation, CNRS-UMR 8089 et Universite de Cergy-Pontoise, 2 Avenue Adolphe Chauvin, 95032, Cergy-Pontoise (France)], E-mail: Thierry.Huillet@u-cergy.fr

    2008-12-19

    The Polya process is an urn scheme arising in the context of contagion spreading. It exhibits unstable persistence effects. The Friedman urn process is dual to the Polya one with antipersistent stabilizing effects. It appears in a safety campaign problem. A Polya-Friedman urn process is investigated with a tuning persistence parameter extrapolating the latter two extreme processes. The study includes the diffusion approximations of both the Polya-Friedman proportion process and the population gap random walk. The structure of the former is a generalized Wright-Fisher diffusion appearing in population genetics. The correlation structure of the latter presents an anomalous character at a critical value of the persistence parameter.

  12. A New Look at a Polya Problem

    Science.gov (United States)

    Lopez-Real, Francis

    2006-01-01

    In this article, the author discusses one of George Polya's geometrical problems. The author offers Polya's solution to the problem, given in the book, "How to Solve It." The reason for its relevance today and alternative solutions to the problem together with an extension are discussed. (Contains 10 figures.)

  13. pEVL: A Linear Plasmid for Generating mRNA IVT Templates With Extended Encoded Poly(A Sequences

    Directory of Open Access Journals (Sweden)

    Alexandra E Grier

    2016-01-01

    Full Text Available Increasing demand for large-scale synthesis of in vitro transcribed (IVT mRNA is being driven by the increasing use of mRNA for transient gene expression in cell engineering and therapeutic applications. An important determinant of IVT mRNA potency is the 3′ polyadenosine (poly(A tail, the length of which correlates with translational efficiency. However, present methods for generation of IVT mRNA rely on templates derived from circular plasmids or PCR products, in which homopolymeric tracts are unstable, thus limiting encoded poly(A tail lengths to ≃120 base pairs (bp. Here, we have developed a novel method for generation of extended poly(A tracts using a previously described linear plasmid system, pJazz. We find that linear plasmids can successfully propagate poly(A tracts up to ≃500 bp in length for IVT mRNA production. We then modified pJazz by removing extraneous restriction sites, adding a T7 promoter sequence upstream from an extended multiple cloning site, and adding a unique type-IIS restriction site downstream from the encoded poly(A tract to facilitate generation of IVT mRNA with precisely defined encoded poly(A tracts and 3′ termini. The resulting plasmid, designated pEVL, can be used to generate IVT mRNA with consistent defined lengths and terminal residue(s.

  14. A 3' Poly(A) Tract Is Required for LINE-1 Retrotransposition.

    Science.gov (United States)

    Doucet, Aurélien J; Wilusz, Jeremy E; Miyoshi, Tomoichiro; Liu, Ying; Moran, John V

    2015-12-01

    L1 retrotransposons express proteins (ORF1p and ORF2p) that preferentially mobilize their encoding RNA in cis, but they also can mobilize Alu RNA and, more rarely, cellular mRNAs in trans. Although these RNAs differ in sequence, each ends in a 3' polyadenosine (poly(A)) tract. Here, we replace the L1 polyadenylation signal with sequences derived from a non-polyadenylated long non-coding RNA (MALAT1), which can form a stabilizing triple helix at the 3' end of an RNA. L1/MALAT RNAs accumulate in cells, lack poly(A) tails, and are translated; however, they cannot retrotranspose in cis. Remarkably, the addition of a 16 or 40 base poly(A) tract downstream of the L1/MALAT triple helix restores retrotransposition in cis. The presence of a poly(A) tract also allows ORF2p to bind and mobilize RNAs in trans. Thus, a 3' poly(A) tract is critical for the retrotransposition of sequences that comprise approximately one billion base pairs of human DNA.

  15. A new yeast poly(A polymerase complex involved in RNA quality control.

    Directory of Open Access Journals (Sweden)

    Stepánka Vanácová

    2005-06-01

    Full Text Available Eukaryotic cells contain several unconventional poly(A polymerases in addition to the canonical enzymes responsible for the synthesis of poly(A tails of nuclear messenger RNA precursors. The yeast protein Trf4p has been implicated in a quality control pathway that leads to the polyadenylation and subsequent exosome-mediated degradation of hypomethylated initiator tRNAMet (tRNAiMet. Here we show that Trf4p is the catalytic subunit of a new poly(A polymerase complex that contains Air1p or Air2p as potential RNA-binding subunits, as well as the putative RNA helicase Mtr4p. Comparison of native tRNAiMet with its in vitro transcribed unmodified counterpart revealed that the unmodified RNA was preferentially polyadenylated by affinity-purified Trf4 complex from yeast, as well as by complexes reconstituted from recombinant components. These results and additional experiments with other tRNA substrates suggested that the Trf4 complex can discriminate between native tRNAs and molecules that are incorrectly folded. Moreover, the polyadenylation activity of the Trf4 complex stimulated the degradation of unmodified tRNAiMet by nuclear exosome fractions in vitro. Degradation was most efficient when coupled to the polyadenylation activity of the Trf4 complex, indicating that the poly(A tails serve as signals for the recruitment of the exosome. This polyadenylation-mediated RNA surveillance resembles the role of polyadenylation in bacterial RNA turnover.

  16. A New Yeast Poly(A Polymerase Complex Involved in RNA Quality Control

    Directory of Open Access Journals (Sweden)

    Vanácová Stepánka

    2005-01-01

    Full Text Available Eukaryotic cells contain several unconventional poly(A polymerases in addition to the canonical enzymes responsible for the synthesis of poly(A tails of nuclear messenger RNA precursors. The yeast protein Trf4p has been implicated in a quality control pathway that leads to the polyadenylation and subsequent exosome-mediated degradation of hypomethylated initiator tRNAMet (tRNAiMet. Here we show that Trf4p is the catalytic subunit of a new poly(A polymerase complex that contains Air1p or Air2p as potential RNA-binding subunits, as well as the putative RNA helicase Mtr4p. Comparison of native tRNAiMet with its in vitro transcribed unmodified counterpart revealed that the unmodified RNA was preferentially polyadenylated by affinity-purified Trf4 complex from yeast, as well as by complexes reconstituted from recombinant components. These results and additional experiments with other tRNA substrates suggested that the Trf4 complex can discriminate between native tRNAs and molecules that are incorrectly folded. Moreover, the polyadenylation activity of the Trf4 complex stimulated the degradation of unmodified tRNAiMet by nuclear exosome fractions in vitro. Degradation was most efficient when coupled to the polyadenylation activity of the Trf4 complex, indicating that the poly(A tails serve as signals for the recruitment of the exosome. This polyadenylation-mediated RNA surveillance resembles the role of polyadenylation in bacterial RNA turnover.

  17. Poly(A) motif prediction using spectral latent features from human DNA sequences

    KAUST Repository

    Xie, Bo

    2013-06-21

    Motivation: Polyadenylation is the addition of a poly(A) tail to an RNA molecule. Identifying DNA sequence motifs that signal the addition of poly(A) tails is essential to improved genome annotation and better understanding of the regulatory mechanisms and stability of mRNA.Existing poly(A) motif predictors demonstrate that information extracted from the surrounding nucleotide sequences of candidate poly(A) motifs can differentiate true motifs from the false ones to a great extent. A variety of sophisticated features has been explored, including sequential, structural, statistical, thermodynamic and evolutionary properties. However, most of these methods involve extensive manual feature engineering, which can be time-consuming and can require in-depth domain knowledge.Results: We propose a novel machine-learning method for poly(A) motif prediction by marrying generative learning (hidden Markov models) and discriminative learning (support vector machines). Generative learning provides a rich palette on which the uncertainty and diversity of sequence information can be handled, while discriminative learning allows the performance of the classification task to be directly optimized. Here, we used hidden Markov models for fitting the DNA sequence dynamics, and developed an efficient spectral algorithm for extracting latent variable information from these models. These spectral latent features were then fed into support vector machines to fine-tune the classification performance.We evaluated our proposed method on a comprehensive human poly(A) dataset that consists of 14 740 samples from 12 of the most abundant variants of human poly(A) motifs. Compared with one of the previous state-of-the-art methods in the literature (the random forest model with expert-crafted features), our method reduces the average error rate, false-negative rate and false-positive rate by 26, 15 and 35%, respectively. Meanwhile, our method makes ?30% fewer error predictions relative to the other

  18. Spatial Reasoning and Polya's Five Planes Problem

    Science.gov (United States)

    Madden, Sean P.; Diaz, Ricardo

    2008-01-01

    Middle and High school students of the twenty-first century possess surprising powers of spatial reasoning. They are assisted by technologies not available to earlier generations. Both of these assertions are demonstrated by students who are challenged with George Polya's classic Five Planes Problem. (Contains 5 figures.)

  19. Seeing the Problem: An Explanation from Polya.

    Science.gov (United States)

    Leinhardt, Gaea; Schwarz, Baruch B.

    1997-01-01

    Examines guessing as a heuristic for problem-solving presented in a taped lesson by George Polya. Analogical models transformed a complex problem to a simpler one and maintained problem identification. Instructional explanations fulfilled two goals simultaneously: (1) teach students how to use guessing as a problem-solving strategy to solve the…

  20. [The effects of SV40 PolyA sequence and its AATAAA signal on upstream GFP gene expression and transcription termination].

    Science.gov (United States)

    Li, Shu-Ping; Feng, Jing-Jing; Wang, Hong-Gang; Wang, Xiu-Fang; Lv, Zhan-Jun

    2012-01-01

    SV40 PolyA (Simian virus 40 PolyA, also called PolyA) sequence is DNA sequence (240 bp) that possesses the activity of transcription termination and can add PolyA tail to mRNA. PolyA contains AATAAA hexanucleotide polyadenylation signal. Fourteen copies of Alu in sense orientation (Alu14) were inserted downstream of GFP in pEGFP-C1 to construct pAlu14 plasmid, and then HeLa cells were transiently transfected with pAlu14. Northern blot and fluorescence microscope were used to observe GFP RNA and protein expressions. Our results found that Alu tandem sequence inhibited remarkably GFP gene expression, but produced higher-molecular-mass GFP fusion RNA. PolyA and its sequence that was deleted AATAAA signal in sense or antisense orientation were inserted between GFP and Alu tandem sequence in pAlu14. The results showed that all the inserted PolyA sequences partly eliminated the inhibition induced by Alu14. PolyA sequences without AATAAA signal in sense or antisense orientation still induced transcription termination. Antisense PolyA (PolyAas) was divided into four fragments that all are 60 bp long and the middle two fragments were named 2F2R and 3F3R. 2F2R or 3F3R was inserted upstream of Alu tandem sequence in pAlu14. The molecular mass of GFP fusion RNA increased when the copy number of 2F2R increased. 2F2R can support transcription elongation when 2F2R is located upstream of other 2F2R. Nevertheless, 2F2R located upstream of Alu tandem sequence can induce transcription termination. Inserting one copy or 64 copies of 3F3R in upstream of Alu tandem sequence caused the production of lower-molecular-mass GFP RNA.

  1. Poly(A) RNA-binding proteins and polyadenosine RNA: new members and novel functions.

    Science.gov (United States)

    Wigington, Callie P; Williams, Kathryn R; Meers, Michael P; Bassell, Gary J; Corbett, Anita H

    2014-01-01

    Poly(A) RNA-binding proteins (Pabs) bind with high affinity and specificity to polyadenosine RNA. Textbook models show a nuclear Pab, PABPN1, and a cytoplasmic Pab, PABPC, where the nuclear PABPN1 modulates poly(A) tail length and the cytoplasmic PABPC stabilizes poly(A) RNA in the cytoplasm and also enhances translation. While these conventional roles are critically important, the Pab family has expanded recently both in number and in function. A number of novel roles have emerged for both PAPBPN1 and PABPC that contribute to the fine-tuning of gene expression. Furthermore, as the characterization of the nucleic acid binding properties of RNA-binding proteins advances, additional proteins that show high affinity and specificity for polyadenosine RNA are being discovered. With this expansion of the Pab family comes a concomitant increase in the potential for Pabs to modulate gene expression. Further complication comes from an expansion of the potential binding sites for Pab proteins as revealed by an analysis of templated polyadenosine stretches present within the transcriptome. Thus, Pabs could influence mRNA fate and function not only by binding to the nontemplated poly(A) tail but also to internal stretches of adenosine. Understanding the diverse functions of Pab proteins is not only critical to understand how gene expression is regulated but also to understand the molecular basis for tissue-specific diseases that occur when Pab proteins are altered. Here we describe both conventional and recently emerged functions for PABPN1 and PABPC and then introduce and discuss three new Pab family members, ZC3H14, hnRNP-Q1, and LARP4.

  2. The cytoplasmic poly(A) polymerases GLD-2 and GLD-4 promote general gene expression via distinct mechanisms.

    Science.gov (United States)

    Nousch, Marco; Yeroslaviz, Assa; Habermann, Bianca; Eckmann, Christian R

    2014-10-01

    Post-transcriptional gene regulation mechanisms decide on cellular mRNA activities. Essential gatekeepers of post-transcriptional mRNA regulation are broadly conserved mRNA-modifying enzymes, such as cytoplasmic poly(A) polymerases (cytoPAPs). Although these non-canonical nucleotidyltransferases efficiently elongate mRNA poly(A) tails in artificial tethering assays, we still know little about their global impact on poly(A) metabolism and their individual molecular roles in promoting protein production in organisms. Here, we use the animal model Caenorhabditis elegans to investigate the global mechanisms of two germline-enriched cytoPAPs, GLD-2 and GLD-4, by combining polysome profiling with RNA sequencing. Our analyses suggest that GLD-2 activity mediates mRNA stability of many translationally repressed mRNAs. This correlates with a general shortening of long poly(A) tails in gld-2-compromised animals, suggesting that most if not all targets are stabilized via robust GLD-2-mediated polyadenylation. By contrast, only mild polyadenylation defects are found in gld-4-compromised animals and few mRNAs change in abundance. Interestingly, we detect a reduced number of polysomes in gld-4 mutants and GLD-4 protein co-sediments with polysomes, which together suggest that GLD-4 might stimulate or maintain translation directly. Our combined data show that distinct cytoPAPs employ different RNA-regulatory mechanisms to promote gene expression, offering new insights into translational activation of mRNAs.

  3. Cytoplasmic RNA: a case of the tail wagging the dog.

    Science.gov (United States)

    Norbury, Chris J

    2013-10-01

    The addition of poly(A) tails to eukaryotic nuclear mRNAs promotes their stability, export to the cytoplasm and translation. Subsequently, the balance between exonucleolytic deadenylation and selective re-establishment of translation-competent poly(A) tails by cytoplasmic poly(A) polymerases is essential for the appropriate regulation of gene expression from oocytes to neurons. In recent years, surprising roles for cytoplasmic poly(A) polymerase-related enzymes that add uridylyl, rather than adenylyl, residues to RNA 3' ends have also emerged. These terminal uridylyl transferases promote the turnover of certain mRNAs but also modify microRNAs, their precursors and other small RNAs to modulate their stability or biological functions.

  4. Journey into Problem Solving: A Gift from Polya

    Science.gov (United States)

    Lederman, Eric

    2009-01-01

    In "How to Solve It", accomplished mathematician and skilled communicator George Polya describes a four-step universal solving technique designed to help students develop mathematical problem-solving skills. By providing a glimpse at the grace with which experts solve problems, Polya provides definable methods that are not exclusive to…

  5. Journey into Problem Solving: A Gift from Polya

    Science.gov (United States)

    Lederman, Eric

    2009-01-01

    In "How to Solve It", accomplished mathematician and skilled communicator George Polya describes a four-step universal solving technique designed to help students develop mathematical problem-solving skills. By providing a glimpse at the grace with which experts solve problems, Polya provides definable methods that are not exclusive to…

  6. Regression analysis using dependent Polya trees.

    Science.gov (United States)

    Schörgendorfer, Angela; Branscum, Adam J

    2013-11-30

    Many commonly used models for linear regression analysis force overly simplistic shape and scale constraints on the residual structure of data. We propose a semiparametric Bayesian model for regression analysis that produces data-driven inference by using a new type of dependent Polya tree prior to model arbitrary residual distributions that are allowed to evolve across increasing levels of an ordinal covariate (e.g., time, in repeated measurement studies). By modeling residual distributions at consecutive covariate levels or time points using separate, but dependent Polya tree priors, distributional information is pooled while allowing for broad pliability to accommodate many types of changing residual distributions. We can use the proposed dependent residual structure in a wide range of regression settings, including fixed-effects and mixed-effects linear and nonlinear models for cross-sectional, prospective, and repeated measurement data. A simulation study illustrates the flexibility of our novel semiparametric regression model to accurately capture evolving residual distributions. In an application to immune development data on immunoglobulin G antibodies in children, our new model outperforms several contemporary semiparametric regression models based on a predictive model selection criterion. Copyright © 2013 John Wiley & Sons, Ltd.

  7. Control of translation and miRNA-dependent repression by a novel poly(A binding protein, hnRNP-Q.

    Directory of Open Access Journals (Sweden)

    Yuri V Svitkin

    Full Text Available Translation control often operates via remodeling of messenger ribonucleoprotein particles. The poly(A binding protein (PABP simultaneously interacts with the 3' poly(A tail of the mRNA and the eukaryotic translation initiation factor 4G (eIF4G to stimulate translation. PABP also promotes miRNA-dependent deadenylation and translational repression of target mRNAs. We demonstrate that isoform 2 of the mouse heterogeneous nuclear protein Q (hnRNP-Q2/SYNCRIP binds poly(A by default when PABP binding is inhibited. In addition, hnRNP-Q2 competes with PABP for binding to poly(A in vitro. Depleting hnRNP-Q2 from translation extracts stimulates cap-dependent and IRES-mediated translation that is dependent on the PABP/poly(A complex. Adding recombinant hnRNP-Q2 to the extracts inhibited translation in a poly(A tail-dependent manner. The displacement of PABP from the poly(A tail by hnRNP-Q2 impaired the association of eIF4E with the 5' m(7G cap structure of mRNA, resulting in the inhibition of 48S and 80S ribosome initiation complex formation. In mouse fibroblasts, silencing of hnRNP-Q2 stimulated translation. In addition, hnRNP-Q2 impeded let-7a miRNA-mediated deadenylation and repression of target mRNAs, which require PABP. Thus, by competing with PABP, hnRNP-Q2 plays important roles in the regulation of global translation and miRNA-mediated repression of specific mRNAs.

  8. Fully Analyzing an Algebraic Polya Urn Model

    CERN Document Server

    Morcrette, Basile

    2012-01-01

    This paper introduces and analyzes a particular class of Polya urns: balls are of two colors, can only be added (the urns are said to be additive) and at every step the same constant number of balls is added, thus only the color compositions varies (the urns are said to be balanced). These properties make this class of urns ideally suited for analysis from an "analytic combinatorics" point-of-view, following in the footsteps of Flajolet-Dumas-Puyhaubert, 2006. Through an algebraic generating function to which we apply a multiple coalescing saddle-point method, we are able to give precise asymptotic results for the probability distribution of the composition of the urn, as well as local limit law and large deviation bounds.

  9. Behavior of adsorbed Poly-A onto sodium montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Palomino-Aquino, Nayeli [Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México (Mexico); Negrón-Mendoza, Alicia, E-mail: negron@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México (Mexico)

    2015-07-23

    The adsorption of Poly-A (a polynucleotide consisting of adenine, ribose and a phosphate group), onto a clay mineral, was studied to investigate the extent of adsorption, the site of binding, and the capacity of the clay to protect Poly-A, while it is adsorbed onto the clay, from external sources of energy. The results showed that Poly-A presented a high percentage of adsorption at the edges of the clay and that the survival of the polynucleotide was superior to irradiating the polymer in the absence of the clay.

  10. Phylogenetic study on structural elements of HIV-1 poly(A region. 1. PolyA and DSE hairpins

    Directory of Open Access Journals (Sweden)

    Zarudnaya M. I.

    2013-11-01

    Full Text Available Genome of human immunodeficiency virus type 1 (HIV-1 is highly heterogeneous. The aim of this work was a phylogenetic study on structural elements of the HIV-1 poly(A region, in particular polyA and DSE hairpins which compose a core poly(A site. Methods. The secondary structure of the HIV-1 core poly(A site has been predicted by the UNAFold program. Results. The structure of the polyA and DSE hairpins has been analysed in 1679 HIV-1 genomes of group M and 18 genomes of simian immunodeficiency virus SIVcpzPtt. We found 244 and 171 different sequences for the HIV-1 polyA and DSE hairpins, respectively. However 70 % of the HIV-1 isolates studied contain one of 7 variants of the polyA hairpin which occur with a frequency 5 % (main variants and 79 % of the isolates contain one of 7 main variants of the DSE hairpin. We also revealed subtype and country specific mutations in these hairpins. We found that the SIV polyA hairpin most closely resembles that found in HIV-1 genomes of B/C subtypes. Conclusions. The results of our large-scale phylogenetic study support some structural models of the HIV-1 5' UTR, in particular the tertiary interaction between the polyA hairpin and the matrix region in HIV-1 gRNA. Possibly, the DSE hairpin appeared in the course of viral evolution of the HIV-1 group M. An exposure of the U/GU-rich element in the apical loop of DSE hairpin could significantly increase the efficiency of pre-mRNA polyadenylation in this HIV-1 group.

  11. Suzuki Meets Polya: Teaching Mathematics to Young Pupils.

    Science.gov (United States)

    Hazlewood, Donald G.; And Others

    1989-01-01

    Describes how Suzuki's methods of teaching young pupils to play the violin can be combined with Polya's ideas on problem solving to teach mathematics to elementary school pupils. Six references are listed. (YP)

  12. The Ccr4-Not deadenylase complex constitutes the main poly(A) removal activity in C. elegans.

    Science.gov (United States)

    Nousch, Marco; Techritz, Nora; Hampel, Daniel; Millonigg, Sophia; Eckmann, Christian R

    2013-09-15

    Post-transcriptional regulatory mechanisms are widely used to control gene expression programs of tissue development and physiology. Controlled 3' poly(A) tail-length changes of mRNAs provide a mechanistic basis of such regulation, affecting mRNA stability and translational competence. Deadenylases are a conserved class of enzymes that facilitate poly(A) tail removal, and their biochemical activities have been mainly studied in the context of single-cell systems. Little is known about the different deadenylases and their biological role in multicellular organisms. In this study, we identify and characterize all known deadenylases of Caenorhabditis elegans, and identify the germ line as tissue that depends strongly on deadenylase activity. Most deadenylases are required for hermaphrodite fertility, albeit to different degrees. Whereas ccr-4 and ccf-1 deadenylases promote germline function under physiological conditions, panl-2 and parn-1 deadenylases are only required under heat-stress conditions. We also show that the Ccr4-Not core complex in nematodes is composed of the two catalytic subunits CCR-4 and CCF-1 and the structural subunit NTL-1, which we find to regulate the stability of CCF-1. Using bulk poly(A) tail measurements with nucleotide resolution, we detect strong deadenylation defects of mRNAs at the global level only in the absence of ccr-4, ccf-1 and ntl-1, but not of panl-2, parn-1 and parn-2. Taken together, this study suggests that the Ccr4-Not complex is the main deadenylase complex in C. elegans germ cells. On the basis of this and as a result of evidence in flies, we propose that the conserved Ccr4-Not complex is an essential component in post-transcriptional regulatory networks promoting animal reproduction.

  13. Structural differentiation of the HIV-1 polyA signals.

    Science.gov (United States)

    Gee, Alan H; Kasprzak, Wojciech; Shapiro, Bruce A

    2006-02-01

    The Human Immunodeficiency Virus Type 1 (HIV-1) encodes the polyadenylation (polyA) signal (AAUAAA) within the highly conserved untranslated region (UTR) at both 5' and 3' terminals of the viral transcript. In polyadenylation, an RNA transcript is cleaved and then elongated with adenine nucleotides while repression of the 5' signal and utilization of the 3' signal occurs. Because experimental studies have yet to analyze the structures of both 5' and 3' signals from a global perspective, other structural conformations involving these signals may exist and could be pivotal to understanding key functional processes. To distinguish the differential regulation of the 5' and 3' polyA signals, we studied the structural tendencies of both the 5' and 3' UTR in HIV-1. Through computational folding predictions of multiple HIV-1 strains using the Massively Parallel Genetic Algorithm (MPGAfold) capable of dynamically elucidating key alternative conformations, the 5' polyA signal was found to be dominantly occluded in a hairpin loop while the 3' polyA signal showed variability between hairpin and linear conformations with a propensity for the linear structure with an asymmetric internal loop. Furthermore, the energies and predictions of these structures indicate that the polyA signals have some metastable characteristics indicating an ability to switch into different conformations that can regulate viral function.

  14. Poly(A binding protein 1 enhances cap-independent translation initiation of neurovirulence factor from avian herpesvirus.

    Directory of Open Access Journals (Sweden)

    Abdessamad Tahiri-Alaoui

    Full Text Available Poly(A binding protein 1 (PABP1 plays a central role in mRNA translation and stability and is a target by many viruses in diverse manners. We report a novel viral translational control strategy involving the recruitment of PABP1 to the 5' leader internal ribosome entry site (5L IRES of an immediate-early (IE bicistronic mRNA that encodes the neurovirulence protein (pp14 from the avian herpesvirus Marek's disease virus serotype 1 (MDV1. We provide evidence for the interaction between an internal poly(A sequence within the 5L IRES and PABP1 which may occur concomitantly with the recruitment of PABP1 to the poly(A tail. RNA interference and reverse genetic mutagenesis results show that a subset of virally encoded-microRNAs (miRNAs targets the inhibitor of PABP1, known as paip2, and therefore plays an indirect role in PABP1 recruitment strategy by increasing the available pool of active PABP1. We propose a model that may offer a mechanistic explanation for the cap-independent enhancement of the activity of the 5L IRES by recruitment of a bona fide initiation protein to the 5' end of the message and that is, from the affinity binding data, still compatible with the formation of 'closed loop' structure of mRNA.

  15. Poly(A) Polymerase Modification and Reverse Transcriptase PCR Amplification of Environmental RNA

    Science.gov (United States)

    Botero, Lina M.; D'Imperio, Seth; Burr, Mark; McDermott, Timothy R.; Young, Mark; Hassett, Daniel J.

    2005-01-01

    We describe a combination of two established techniques for a novel application for constructing full-length cDNA clone libraries from environmental RNA. The cDNA was cloned without the use of prescribed primers that target specific genes, and the procedure did not involve random priming. Purified RNA was first modified by addition of a poly(A) tail and then was amplified by using a commercially available reverse transcriptase PCR (RT-PCR) cDNA synthesis kit. To demonstrate the feasibility of this approach, a cDNA clone library was constructed from size-fractionated RNA (targeting 16S rRNA) purified from a geothermally heated soil in Yellowstone National Park in Wyoming. The resulting cDNA library contained clones representing Bacteria and Eukarya taxa and several mRNAs. There was no exact clone match between this library and a separate cDNA library generated from an RT-PCR performed with unmodified rRNA and Bacteria-specific forward and universal reverse primers that were designed from cultivated organisms; however, both libraries contained representatives of the Firmicutes and the α-Proteobacteria. Unexpectedly, there were no Archaea clones in the library generated from poly(A)-modified RNA. Additional RT-PCRs performed with universal and Archaea-biased primers and unmodified RNA demonstrated the presence of novel Archaea in the soil. Experiments with pure cultures of Sulfolobus solfataricus and Halobacterium halobium revealed that some Archaea rRNA may not be a suitable substrate for the poly(A) tail modification step. The protocol described here demonstrates the feasibility of directly accessing prokaryote RNA (rRNA and/or mRNA) in environmental samples, but the results also illustrate potentially important problems. PMID:15746328

  16. On the Exact Solution of a Generalized Polya Process

    Directory of Open Access Journals (Sweden)

    Hidetoshi Konno

    2010-01-01

    Full Text Available There are two types of master equations in describing nonequilibrium phenomena with memory effect: (i the memory function type and (ii the nonstationary type. A generalized Polya process is studied within the framework of a non-stationary type master equation approach. For a transition-rate with an arbitrary time-dependent relaxation function, the exact solution of a generalized Polya process is obtained. The characteristic features of temporal variation of the solution are displayed for some typical time-dependent relaxation functions reflecting memory in the systems.

  17. Reviving Polya's "Look Back" in a Singapore School

    Science.gov (United States)

    Leong, Yew Hoong; Tay, Eng Guan; Toh, Tin Lam; Quek, Khiok Seng; Dindyal, Jaguthsing

    2011-01-01

    This study is based on the stance that Polya's "Look Back," though understudied, remains relevant to Mathematics curricula that place emphasis on problem solving. Although the Singapore Mathematics curriculum adopts the goal of teaching Look Back, research about how it is carried out in actual classroom practice is rare. In our project,…

  18. Poly(A) RNA a new component of Cajal bodies.

    Science.gov (United States)

    Kołowerzo, Agnieszka; Smoliński, Dariusz Jan; Bednarska, Elzbieta

    2009-07-01

    In European larch microsporocytes, spherical structures 0.5 to 6 microm in diameter are present in which poly(A) RNA accumulates. There were one to several bodies per cell and they were often present in the vicinity of the nucleolus. No nascent transcripts were observed within them. Splicing factors of the SR family, including protein SC35, which participates in bringing the 3' and 5' sites closer in the splicing reaction, were also not observed. The absence of the above-mentioned elements within bodies containing poly(A) RNA disqualifies them as sites of synthesis and preliminary stages of primary transcript maturation. However, they contained abundant elements of the splicing machinery commonly occurring in Cajal bodies, i.e., Sm proteins or small nuclear RNA (snRNA). The molecular composition as well as the characteristic ultrastructure of bodies containing poly(A) RNA proves that these were Cajal bodies. This is the first report of such poly(A) RNA localization.

  19. Problem Solving: Polya's Heuristic Applied to Psychological Research.

    Science.gov (United States)

    Damarin, Suzanne K.

    Using the "How to Solve It" list developed by Polya as a vehicle of comparison, research findings and key concepts from the psychological study of problem solving are applied to mathematical problem solving. Hypotheses concerning the interpretation of psychological phenomena for mathematical problem situations are explored. Several areas…

  20. Characterization of genes encoding poly(A polymerases in plants: evidence for duplication and functional specialization.

    Directory of Open Access Journals (Sweden)

    Lisa R Meeks

    Full Text Available BACKGROUND: Poly(A polymerase is a key enzyme in the machinery that mediates mRNA 3' end formation in eukaryotes. In plants, poly(A polymerases are encoded by modest gene families. To better understand this multiplicity of genes, poly(A polymerase-encoding genes from several other plants, as well as from Selaginella, Physcomitrella, and Chlamydomonas, were studied. METHODOLOGY/PRINCIPAL FINDINGS: Using bioinformatics tools, poly(A polymerase-encoding genes were identified in the genomes of eight species in the plant lineage. Whereas Chlamydomonas reinhardtii was found to possess a single poly(A polymerase gene, other species possessed between two and six possible poly(A polymerase genes. With the exception of four intron-lacking genes, all of the plant poly(A polymerase genes (but not the C. reinhardtii gene possessed almost identical intron positions within the poly(A polymerase coding sequences, suggesting that all plant poly(A polymerase genes derive from a single ancestral gene. The four Arabidopsis poly(A polymerase genes were found to be essential, based on genetic analysis of T-DNA insertion mutants. GFP fusion proteins containing three of the four Arabidopsis poly(A polymerases localized to the nucleus, while one such fusion protein was localized in the cytoplasm. The fact that this latter protein is largely pollen-specific suggests that it has important roles in male gametogenesis. CONCLUSIONS/SIGNIFICANCE: Our results indicate that poly(A polymerase genes have expanded from a single ancestral gene by a series of duplication events during the evolution of higher plants, and that individual members have undergone sorts of functional specialization so as to render them essential for plant growth and development. Perhaps the most interesting of the plant poly(A polymerases is a novel cytoplasmic poly(A polymerase that is expressed in pollen in Arabidopsis; this is reminiscent of spermatocyte-specific cytoplasmic poly(A polymerases in

  1. Boltzmann Samplers, P\\'olya Theory, and Cycle Pointing

    CERN Document Server

    Bodirsky, Manuel; Kang, Mihyun; Vigerske, Stefan

    2010-01-01

    We introduce a general method to count unlabeled combinatorial structures and to efficiently generate them at random. The approach is based on pointing unlabeled structures in an "unbiased" way that a structure of size n gives rise to n pointed structures. We extend Polya theory to the corresponding pointing operator, and present a random sampling framework based on both the principles of Boltzmann sampling and on P\\'olya operators. All previously known unlabeled construction principles for Boltzmann samplers are special cases of our new results. Our method is illustrated on several examples: in each case, we provide enumerative results and efficient random samplers. The approach applies to unlabeled families of plane and nonplane unrooted trees, and tree-like structures in general, but also to families of graphs (such as cacti graphs and outerplanar graphs) and families of planar maps.

  2. On Polya's inequality for torsional rigidity and first Dirichlet eigenvalue

    OpenAIRE

    Berg, M. van den; Ferone, V.; Nitsch, C.; Trombetti, C.

    2016-01-01

    Let $\\Omega$ be an open set in Euclidean space with finite Lebesgue measure $|\\Omega|$. We obtain some properties of the set function $F:\\Omega\\mapsto \\R^+$ defined by $$ F(\\Omega)=\\frac{T(\\Omega)\\lambda_1(\\Omega)}{|\\Omega|} ,$$ where $T(\\Omega)$ and $\\lambda_1(\\Omega)$ are the torsional rigidity and the first eigenvalue of the Dirichlet Laplacian respectively. We improve the classical P\\'olya bound $F(\\Omega)\\le 1,$ and show that $$F(\\Omega)\\le 1- \

  3. A multiple more accurate Hardy-Littlewood-Polya inequality

    Directory of Open Access Journals (Sweden)

    Qiliang Huang

    2012-11-01

    Full Text Available By introducing multi-parameters and conjugate exponents and using Euler-Maclaurin’s summation formula, we estimate the weight coefficient and prove a multiple more accurate Hardy-Littlewood-Polya (H-L-P inequality, which is an extension of some earlier published results. We also prove that the constant factor in the new inequality is the best possible, and obtain its equivalent forms.

  4. Compliance of POLYAS with the Common Criteria Protection Profile

    CERN Document Server

    Menke, Niels

    2010-01-01

    In 2008, the German Federal Office for Information Security issued the common criteria protection profile for Online Voting Products (PP-0037). Accord- ingly, we evaluated the Polyas electronic voting system, which is used for legally binding elections in several international organizations (German Gesellschaft for Informatik, GI, among others), for compliance with the common criteria protection profile and worked toward fulfilling the given requirements. In this article we pre- sent the findings of the process of creating a compliant security target, necessary restrictions and assumptions to the system design as well as the workings of the committee, and architectural and procedural changes made necessary.

  5. PACdb: PolyA Cleavage Site and 3'-UTR Database.

    Science.gov (United States)

    Brockman, J Michael; Singh, Priyam; Liu, Donglin; Quinlan, Sean; Salisbury, Jesse; Graber, Joel H

    2005-09-15

    The PolyA Cleavage Site and 3'-UTR Database (PACdb) is a web-accessible database that catalogs putative 3'-processing sites and 3'-UTR sequences for multiple organisms. Sites have been identified primarily via expressed sequence tag-genome alignments, enabling delineation of both the specificities and heterogeneity of 3'-processing events. By web browser or CGI: PACdb: http://harlequin.jax.org/pacdb/; AtPACdb: http://harlequin.jax.org/atpacdb/. Available online at http://harlequin.jax.org/pacdb/supplemental.php.

  6. An analogue of Polya's theorem for piecewise holomorphic functions

    Science.gov (United States)

    Buslaev, V. I.

    2015-12-01

    A well-known result due to Polya for a function given by its holomorphic germ at z=∞ is extended to the case of a piecewise holomorphic function on an arbitrary compact set in \\overline{ C}. This result is applied to the problem of the existence of compact sets that have the minimum transfinite diameter in the external field of the logarithmic potential of a negative unit charge among all compact sets such that a certain multivalued analytic function is single-valued and piecewise holomorphic on their complement. Bibliography: 13 titles.

  7. POLYAR, a new computer program for prediction of poly(A sites in human sequences

    Directory of Open Access Journals (Sweden)

    Qamar Raheel

    2010-11-01

    Full Text Available Abstract Background mRNA polyadenylation is an essential step of pre-mRNA processing in eukaryotes. Accurate prediction of the pre-mRNA 3'-end cleavage/polyadenylation sites is important for defining the gene boundaries and understanding gene expression mechanisms. Results 28761 human mapped poly(A sites have been classified into three classes containing different known forms of polyadenylation signal (PAS or none of them (PAS-strong, PAS-weak and PAS-less, respectively and a new computer program POLYAR for the prediction of poly(A sites of each class was developed. In comparison with polya_svm (till date the most accurate computer program for prediction of poly(A sites while searching for PAS-strong poly(A sites in human sequences, POLYAR had a significantly higher prediction sensitivity (80.8% versus 65.7% and specificity (66.4% versus 51.7% However, when a similar sort of search was conducted for PAS-weak and PAS-less poly(A sites, both programs had a very low prediction accuracy, which indicates that our knowledge about factors involved in the determination of the poly(A sites is not sufficient to identify such polyadenylation regions. Conclusions We present a new classification of polyadenylation sites into three classes and a novel computer program POLYAR for prediction of poly(A sites/regions of each of the class. In tests, POLYAR shows high accuracy of prediction of the PAS-strong poly(A sites, though this program's efficiency in searching for PAS-weak and PAS-less poly(A sites is not very high but is comparable to other available programs. These findings suggest that additional characteristics of such poly(A sites remain to be elucidated. POLYAR program with a stand-alone version for downloading is available at http://cub.comsats.edu.pk/polyapredict.htm.

  8. Poly(A) binding proteins located at the inner surface of resealed nuclear envelopes.

    Science.gov (United States)

    Prochnow, D; Riedel, N; Agutter, P S; Fasold, H

    1990-04-25

    We have used a photoreactive cross-linking reagent, poly(A/8-N3-A) (a poly(A) of average molecular mass of 100 kDa in which 5-10% of the A residues are replaced by 8-N3-A), to label poly(A) binding proteins of rat liver nuclear envelopes. This reagent was prepared by polymerizing a mixture of ADP and 8-N3-ADP with polynucleotide phosphorylase. The purified poly(A) was labeled in the 5'-position with a 32P group. In nuclear envelopes prepared by a low salt DNase I procedure, the poly(A/8-N3-A) labeled a protein-nucleic acid complex of approximately 270 kDa, which on degradation with RNase U2 or NaOH at pH 10 yielded two polypeptides of approximately 50 and 30 kDa. These photoreaction products were markedly decreased when resealed nuclear envelopes or non-nuclear envelope proteins were irradiated in the presence of poly(A/8-N3-A). The affinity labeling was intensified when resealed vesicles were made leaky by freezing or ultrasonication, suggesting that the poly(A) binding proteins are accessible from the nucleoplasmic but not the cytoplasmic face of the envelope. Moreover binding was specific for poly(A). Alternative reagents, random poly(A/8-N3-A,C,G,U) of about 100 kDa and poly(dA) (molecular mass between 350 and 515 kDa), showed a very low affinity for poly(A) recognition proteins in the low salt DNase I-treated nuclear envelopes; the 270-kDa band was labeled only weakly. The binding site was not protected by poly(A,C,G,U), weakly by poly(dA), and distinctly by poly(A).

  9. Involvement of non-polyalanine (polyA) residues in aggregation of polyA proteins: Clue for inhibition of aggregation.

    Science.gov (United States)

    Sharma, Vandna; Ghosh, Kalyan Sundar

    2014-11-20

    Presence of polyalanine (polyA) stretches in some proteins is found to be associated with their aggregation, which causes disorders in various developmental processes. In this work, inherent propensities towards aggregation of some residues, which are not part of the polyA stretches, have been identified by using the primary sequences of seven polyA proteins with the help of Betascan, PASTA and Tango programs and explored unambiguously. This provides a basis for proposing molecular mechanism of this type of aggregation. Reported suppression of aggregation of polyA proteins by chaperones like HSP40 and HSP70 is substantiated through molecular docking. The hydrophobic residues of identified aggregating region are found to be interacting with hydrophobic surface of chaperones. This suggests a crucial clue for possible way to inhibit the aggregation of such proteins. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Polya's Legacy: Fully Forgotten or Getting a New Perspective in Theory and Practice?

    Science.gov (United States)

    Passmore, Tim

    2007-01-01

    Problem solving and student-centred learning have received a great deal of attention in mathematics curricula for schools and in some universities. Much of this emphasis developed from the pioneering work of George Polya in heuristics, problem solving, and mathematics education. In this study, the author reviews Polya's work, and some of its later…

  11. Polya conditions for multivariate Birkhoff interpolation: from general to rectangular sets of nodes

    NARCIS (Netherlands)

    Crainic, M.; Crainic, N.

    2010-01-01

    Polya conditions are certain algebraic inequalities that regular Birkhoff interpolation schemes must satisfy, and they are useful in deciding if a given scheme is regular or not. Here we review the classical Polya condition and then we show how it can be strengthened in the case of rectangular

  12. Ending the message: poly(A) signals then and now

    Science.gov (United States)

    Proudfoot, Nick J.

    2011-01-01

    Polyadenylation [poly(A)] signals (PAS) are a defining feature of eukaryotic protein-coding genes. The central sequence motif AAUAAA was identified in the mid-1970s and subsequently shown to require flanking, auxiliary elements for both 3′-end cleavage and polyadenylation of premessenger RNA (pre-mRNA) as well as to promote downstream transcriptional termination. More recent genomic analysis has established the generality of the PAS for eukaryotic mRNA. Evidence for the mechanism of mRNA 3′-end formation is outlined, as is the way this RNA processing reaction communicates with RNA polymerase II to terminate transcription. The widespread phenomenon of alternative poly(A) site usage and how this interrelates with pre-mRNA splicing is then reviewed. This shows that gene expression can be drastically affected by how the message is ended. A central theme of this review is that while genomic analysis provides generality for the importance of PAS selection, detailed mechanistic understanding still requires the direct analysis of specific genes by genetic and biochemical approaches. PMID:21896654

  13. Spatially dependent polya tree modeling for survival data.

    Science.gov (United States)

    Zhao, Luping; Hanson, Timothy E

    2011-06-01

    With the proliferation of spatially oriented time-to-event data, spatial modeling in the survival context has received increased recent attention. A traditional way to capture a spatial pattern is to introduce frailty terms in the linear predictor of a semiparametric model, such as proportional hazards or accelerated failure time. We propose a new methodology to capture the spatial pattern by assuming a prior based on a mixture of spatially dependent Polya trees for the baseline survival in the proportional hazards model. Thanks to modern Markov chain Monte Carlo (MCMC) methods, this approach remains computationally feasible in a fully hierarchical Bayesian framework. We compare the spatially dependent mixture of Polya trees (MPT) approach to the traditional spatial frailty approach, and illustrate the usefulness of this method with an analysis of Iowan breast cancer survival data from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute. Our method provides better goodness of fit over the traditional alternatives as measured by log pseudo marginal likelihood (LPML), the deviance information criterion (DIC), and full sample score (FSS) statistics. © 2010, The International Biometric Society.

  14. Genome-Wide Analysis of PAPS1-Dependent Polyadenylation Identifies Novel Roles for Functionally Specialized Poly(A Polymerases in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Christian Kappel

    2015-08-01

    Full Text Available The poly(A tail at 3' ends of eukaryotic mRNAs promotes their nuclear export, stability and translational efficiency, and changes in its length can strongly impact gene expression. The Arabidopsis thaliana genome encodes three canonical nuclear poly(A polymerases, PAPS1, PAPS2 and PAPS4. As shown by their different mutant phenotypes, these three isoforms are functionally specialized, with PAPS1 modifying organ growth and suppressing a constitutive immune response. However, the molecular basis of this specialization is largely unknown. Here, we have estimated poly(A-tail lengths on a transcriptome-wide scale in wild-type and paps1 mutants. This identified categories of genes as particularly strongly affected in paps1 mutants, including genes encoding ribosomal proteins, cell-division factors and major carbohydrate-metabolic proteins. We experimentally verified two novel functions of PAPS1 in ribosome biogenesis and redox homoeostasis that were predicted based on the analysis of poly(A-tail length changes in paps1 mutants. When overlaying the PAPS1-dependent effects observed here with coexpression analysis based on independent microarray data, the two clusters of transcripts that are most closely coexpressed with PAPS1 show the strongest change in poly(A-tail length and transcript abundance in paps1 mutants in our analysis. This suggests that their coexpression reflects at least partly the preferential polyadenylation of these transcripts by PAPS1 versus the other two poly(A-polymerase isoforms. Thus, transcriptome-wide analysis of poly(A-tail lengths identifies novel biological functions and likely target transcripts for polyadenylation by PAPS1. Data integration with large-scale co-expression data suggests that changes in the relative activities of the isoforms are used as an endogenous mechanism to co-ordinately modulate plant gene expression.

  15. Tailings management

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-05-01

    Careful planning and water management is essential to the proper management of conventional tailings impoundments. Alternatives, like dry stacking and tailings backfill are becoming more widely used. Effective closure is important, especially if acid rock drainage (ARD) is to be avoided. 11 refs., 3 photos.

  16. [Analysis of polyA, polyU and double-stranded complex polyA x polyU via Raman spectroscopy].

    Science.gov (United States)

    Liao, Yu-bo; Meng, Yao-yong; Lei, Hao-dong; Wang, Ying

    2007-05-01

    The Raman spectra of PolyA, PolyU and their double-stranded complex were measured, and the spectral changes upon the formation of double-stranded complex were studied. The experimental results show: (1) Under the experimental conditions used in the present work (0.14 mol x L(-1) NaCl, 1 mmol x L(-1) Tris solution, neutral pH and 15 degrees C), PolyU, PolyA and PolyA x PolyU occur as random-coiled, A-single-stranded helical and A-double-stranded helical conformations, respectively. One of the main spectral differences between the latter two conformations and the former one is the Raman band near 814 cm(-1) of ordered structures. Another difference is in the full width at half the maximum (i.e. FWHM) of the band near 1100 cm(-1). The FWHM of the band 1100 cm(-1) of PolyA is the same as that of PolyA x PolyU, while the band of PolyU shows remarkable broadening. In addition, we found that the conformation of PolyA is somewhat not so ordered as that of its duplex, which can be concluded from the value of I814/I1100 of the two polynucleotides. (2) The formation of duplex makes base-base stacking interactions much stronger, and the conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some corresponding band shift. In this process, PolyU underwent more significant spectral changes than PolyA. As spectral markers, these results can be of great importance in Raman spectral signal detection of gene-chips.

  17. Mixtures of Polya trees for flexible spatial frailty survival modelling.

    Science.gov (United States)

    Zhao, Luping; Hanson, Timothy E; Carlin, Bradley P

    2009-06-01

    Mixtures of Polya trees offer a very flexible nonparametric approach for modelling time-to-event data. Many such settings also feature spatial association that requires further sophistication, either at the point level or at the lattice level. In this paper, we combine these two aspects within three competing survival models, obtaining a data analytic approach that remains computationally feasible in a fully hierarchical Bayesian framework using Markov chain Monte Carlo methods. We illustrate our proposed methods with an analysis of spatially oriented breast cancer survival data from the Surveillance, Epidemiology and End Results program of the National Cancer Institute. Our results indicate appreciable advantages for our approach over competing methods that impose unrealistic parametric assumptions, ignore spatial association or both.

  18. Poly(A) RNAs including coding proteins RNAs occur in plant Cajal bodies.

    Science.gov (United States)

    Niedojadło, Janusz; Kubicka, Ewa; Kalich, Beata; Smoliński, Dariusz J

    2014-01-01

    The localisation of poly(A) RNA in plant cells containing either reticular (Allium cepa) or chromocentric (Lupinus luteus, Arabidopsis thaliana) nuclei was studied through in situ hybridisation. In both types of nuclei, the amount of poly(A) RNA was much greater in the nucleus than in the cytoplasm. In the nuclei, poly(A) RNA was present in structures resembling nuclear bodies. The molecular composition as well as the characteristic ultrastructure of the bodies containing poly(A) RNA demonstrated that they were Cajal bodies. We showed that some poly(A) RNAs in Cajal bodies code for proteins. However, examination of the localisation of active RNA polymerase II and in situ run-on transcription assays both demonstrated that CBs are not sites of transcription and that BrU-containing RNA accumulates in these structures long after synthesis. In addition, it was demonstrated that accumulation of poly(A) RNA occurs in the nuclei and CBs of hypoxia-treated cells. Our findings indicated that CBs may be involved in the later stages of poly(A) RNA metabolism, playing a role storage or retention.

  19. Poly(A RNAs including coding proteins RNAs occur in plant Cajal bodies.

    Directory of Open Access Journals (Sweden)

    Janusz Niedojadło

    Full Text Available The localisation of poly(A RNA in plant cells containing either reticular (Allium cepa or chromocentric (Lupinus luteus, Arabidopsis thaliana nuclei was studied through in situ hybridisation. In both types of nuclei, the amount of poly(A RNA was much greater in the nucleus than in the cytoplasm. In the nuclei, poly(A RNA was present in structures resembling nuclear bodies. The molecular composition as well as the characteristic ultrastructure of the bodies containing poly(A RNA demonstrated that they were Cajal bodies. We showed that some poly(A RNAs in Cajal bodies code for proteins. However, examination of the localisation of active RNA polymerase II and in situ run-on transcription assays both demonstrated that CBs are not sites of transcription and that BrU-containing RNA accumulates in these structures long after synthesis. In addition, it was demonstrated that accumulation of poly(A RNA occurs in the nuclei and CBs of hypoxia-treated cells. Our findings indicated that CBs may be involved in the later stages of poly(A RNA metabolism, playing a role storage or retention.

  20. The Influence of SV40 polyA on Gene Expression of Baculovirus Expression Vector Systems.

    Directory of Open Access Journals (Sweden)

    Tamer Z Salem

    Full Text Available The simian virus 40 polyadenylation signal (SV40 polyA has been routinely inserted downstream of the polyhedrin promoter in many baculovirus expression vector systems (BEVS. In the baculovirus prototype Autographa californica multiple nucleopolyhedrovirus (AcMNPV, the polyhedrin promoter (very late promoter transcribes its gene by a viral RNA polymerase therefore there is no supporting evidence that SV40 polyA is required for the proper gene expression under the polyhedrin promoter. Moreover, the effect of the SV40 polyA sequence on the polyhedrin promoter activity has not been tested either at its natural polyhedrin locus or in other loci in the viral genome. In order to test the significance of adding the SV40 polyA sequence on gene expression, the expression of the enhanced green fluorescent protein (egfp was evaluated with and without the presence of SV40 polyA under the control of the polyhedrin promoter at different genomic loci (polyherin, ecdysteroid UDP-glucosyltransferase (egt, and gp37. In this study, spectrofluorometry and western blot showed reduction of EGFP protein for all recombinant viruses with SV40 polyA, whereas qPCR showed an increase in the egfp mRNA levels. Therefore, we conclude that SV40 polyA increases mRNA levels but decreases protein production in the BEVS when the polyhedrin promoter is used at different loci. This work suggests that SV40 polyA in BEVSs should be replaced by an AcMNPV late gene polyA for optimal protein production or left untouched for optimal RNA production (RNA interference applications.

  1. The Influence of SV40 polyA on Gene Expression of Baculovirus Expression Vector Systems.

    Science.gov (United States)

    Salem, Tamer Z; Seaborn, Craig P; Turney, Colin M; Xue, Jianli; Shang, Hui; Cheng, Xiao-Wen

    2015-01-01

    The simian virus 40 polyadenylation signal (SV40 polyA) has been routinely inserted downstream of the polyhedrin promoter in many baculovirus expression vector systems (BEVS). In the baculovirus prototype Autographa californica multiple nucleopolyhedrovirus (AcMNPV), the polyhedrin promoter (very late promoter) transcribes its gene by a viral RNA polymerase therefore there is no supporting evidence that SV40 polyA is required for the proper gene expression under the polyhedrin promoter. Moreover, the effect of the SV40 polyA sequence on the polyhedrin promoter activity has not been tested either at its natural polyhedrin locus or in other loci in the viral genome. In order to test the significance of adding the SV40 polyA sequence on gene expression, the expression of the enhanced green fluorescent protein (egfp) was evaluated with and without the presence of SV40 polyA under the control of the polyhedrin promoter at different genomic loci (polyherin, ecdysteroid UDP-glucosyltransferase (egt), and gp37). In this study, spectrofluorometry and western blot showed reduction of EGFP protein for all recombinant viruses with SV40 polyA, whereas qPCR showed an increase in the egfp mRNA levels. Therefore, we conclude that SV40 polyA increases mRNA levels but decreases protein production in the BEVS when the polyhedrin promoter is used at different loci. This work suggests that SV40 polyA in BEVSs should be replaced by an AcMNPV late gene polyA for optimal protein production or left untouched for optimal RNA production (RNA interference applications).

  2. Molecular cloning and characterization of a novel isoform of the non-canonical poly(A) polymerase PAPD7

    Energy Technology Data Exchange (ETDEWEB)

    Ogami, Koichi; Cho, Rihe [Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603 (Japan); Hoshino, Shin-ichi, E-mail: hoshino@phar.nagoya-cu.ac.jp [Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603 (Japan)

    2013-03-01

    Highlights: ► So far, only an enzymatically inactive isoform of PAPD7 was reported. ► The novel isoform: PAPD7 l shows robust nucleotidyl transferase activity. ► The newly identified amino terminal region is required for the activity. ► PAPD7 l localizes to the nucleoplasm. ► The N terminal region identified is also required for the nuclear localization. - Abstract: Non-canonical poly(A) polymerases (ncPAPs) catalyze the addition of poly(A) tail to the 3′ end of RNA to play pivotal roles in the regulation of gene expression and also in quality control. Here we identified a novel isoform of the 7th member of ncPAPs: PAPD7 (PAPD7 l), which contains 230 extra amino acids at the amino terminus of the previously identified PAPD7 (PAPD7 s). In sharp contrast to the inactive PAPD7 s, PAPD7 l showed robust nucleotidyl transferase activity when tethered to an RNA. A region required for the activity was localized to 187–219 aa, and this region was also required for the nuclear retention of PAPD7 l. Western blot analysis revealed that 94 kDa band (corresponding to PAPD7 l) but not 62 kDa band (corresponding to PAPD7 s) detected by PAPD7 antibody was specifically depleted by treatment with PAPD7 siRNA in both HeLa and U2OS cells. These results suggest that PAPD7 l is the major and active isoform of PAPD7 expressed in cells.

  3. Mitochondrial RNAs of myxomycetes terminate with non-encoded 3′ poly(U) tails

    Science.gov (United States)

    Horton, Tamara L.; Landweber, Laura F.

    2000-01-01

    We examined the 3′ ends of edited RNAs from the myxomycetes Stemonitis flavogenita and Physarum polycephalum using a modified anchor PCR approach. Surprisingly, we found that poly(A) tails are missing from the cytochrome c oxidase subunit 1 mRNA (coI) from both species and the cytochrome c oxidase subunit 3 mRNA (cox3) from P.polycephalum. Instead, non-encoded poly(U) tails of varying length were discovered at the 3′ ends of these transcripts. These are the first described examples of 3′ poly(U) tails on mature mRNAs in any system. PMID:11095686

  4. The Polya Tree Sampler: Towards Efficient and Automatic Independent Metropolis-Hastings Proposals.

    Science.gov (United States)

    Hanson, Timothy E; Monteiro, João V D; Jara, Alejandro

    2011-03-01

    We present a simple, efficient, and computationally cheap sampling method for exploring an un-normalized multivariate density on ℝ(d), such as a posterior density, called the Polya tree sampler. The algorithm constructs an independent proposal based on an approximation of the target density. The approximation is built from a set of (initial) support points - data that act as parameters for the approximation - and the predictive density of a finite multivariate Polya tree. In an initial "warming-up" phase, the support points are iteratively relocated to regions of higher support under the target distribution to minimize the distance between the target distribution and the Polya tree predictive distribution. In the "sampling" phase, samples from the final approximating mixture of finite Polya trees are used as candidates which are accepted with a standard Metropolis-Hastings acceptance probability. Several illustrations are presented, including comparisons of the proposed approach to Metropolis-within-Gibbs and delayed rejection adaptive Metropolis algorithm.

  5. Comparison Theorems for Eigenvalues of Elliptic Operators and the Generalized Polya Conjecture

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qiaoling, E-mail: wang@impa.br; Xia, Changyu, E-mail: xia@mat.unb.b [UnB, Departamento de Matematica (Brazil)

    2010-09-15

    We establish comparison theorems for eigenvalues between higher order elliptic equations on compact manifolds with boundary. As an application, it follows that if the Polya conjecture is true then so is the generalized Polya conjecture proposed by Ku et al. (J Differ Equ 97:127-139, 1992). We also obtain new lower bound for the eigenvalues of higher order elliptic equations on bounded domains in a Euclidean space.

  6. Bayesian nonparametric meta-analysis using Polya tree mixture models.

    Science.gov (United States)

    Branscum, Adam J; Hanson, Timothy E

    2008-09-01

    Summary. A common goal in meta-analysis is estimation of a single effect measure using data from several studies that are each designed to address the same scientific inquiry. Because studies are typically conducted in geographically disperse locations, recent developments in the statistical analysis of meta-analytic data involve the use of random effects models that account for study-to-study variability attributable to differences in environments, demographics, genetics, and other sources that lead to heterogeneity in populations. Stemming from asymptotic theory, study-specific summary statistics are modeled according to normal distributions with means representing latent true effect measures. A parametric approach subsequently models these latent measures using a normal distribution, which is strictly a convenient modeling assumption absent of theoretical justification. To eliminate the influence of overly restrictive parametric models on inferences, we consider a broader class of random effects distributions. We develop a novel hierarchical Bayesian nonparametric Polya tree mixture (PTM) model. We present methodology for testing the PTM versus a normal random effects model. These methods provide researchers a straightforward approach for conducting a sensitivity analysis of the normality assumption for random effects. An application involving meta-analysis of epidemiologic studies designed to characterize the association between alcohol consumption and breast cancer is presented, which together with results from simulated data highlight the performance of PTMs in the presence of nonnormality of effect measures in the source population.

  7. The 25 kDa subunit of cleavage factor Im Is a RNA-binding protein that interacts with the poly(A polymerase in Entamoeba histolytica.

    Directory of Open Access Journals (Sweden)

    Marisol Pezet-Valdez

    Full Text Available In eukaryotes, polyadenylation of pre-mRNA 3' end is essential for mRNA export, stability and translation. Taking advantage of the knowledge of genomic sequences of Entamoeba histolytica, the protozoan responsible for human amoebiasis, we previously reported the putative polyadenylation machinery of this parasite. Here, we focused on the predicted protein that has the molecular features of the 25 kDa subunit of the Cleavage Factor Im (CFIm25 from other organisms, including the Nudix (nucleoside diphosphate linked to another moiety X domain, as well as the RNA binding domain and the PAP/PAB interacting region. The recombinant EhCFIm25 protein (rEhCFIm25 was expressed in bacteria and used to generate specific antibodies in rabbit. Subcellular localization assays showed the presence of the endogenous protein in nuclear and cytoplasmic fractions. In RNA electrophoretic mobility shift assays, rEhCFIm25 was able to form specific RNA-protein complexes with the EhPgp5 mRNA 3´ UTR used as probe. In addition, Pull-Down and LC/ESI-MS/MS tandem mass spectrometry assays evidenced that the putative EhCFIm25 was able to interact with the poly(A polymerase (EhPAP that is responsible for the synthesis of the poly(A tail in other eukaryotic cells. By Far-Western experiments, we confirmed the interaction between the putative EhCFIm25 and EhPAP in E. histolytica. Taken altogether, our results showed that the putative EhCFIm25 is a conserved RNA binding protein that interacts with the poly(A polymerase, another member of the pre-mRNA 3' end processing machinery in this protozoan parasite.

  8. Endosymbiont gene functions impaired and rescued by polymerase infidelity at poly(A) tracts

    Science.gov (United States)

    Tamas, Ivica; Wernegreen, Jennifer J.; Nystedt, Björn; Kauppinen, Seth N.; Darby, Alistair C.; Gomez-Valero, Laura; Lundin, Daniel; Poole, Anthony M.; Andersson, Siv G. E.

    2008-01-01

    Among host-dependent bacteria that have evolved by extreme reductive genome evolution, long-term bacterial endosymbionts of insects have the smallest (160–790 kb) and most A + T-rich (>70%) bacterial genomes known to date. These genomes are riddled with poly(A) tracts, and 5–50% of genes contain tracts of 10 As or more. Here, we demonstrate transcriptional slippage at poly(A) tracts within genes of Buchnera aphidicola associated with aphids and Blochmannia pennsylvanicus associated with ants. Several tracts contain single frameshift deletions; these apparent pseudogenes showed patterns of constraint consistent with purifying selection on the encoded proteins. Transcriptional slippage yielded a heterogeneous population of transcripts with variable numbers of As in the tract. Across several frameshifted genes, including B. aphidicola cell wall biosynthesis genes and a B. pennsylvanicus histidine biosynthesis gene, 12–50% of transcripts contained corrected reading frames that could potentially yield full-length proteins. In situ immunostaining confirmed the production of the cell wall biosynthetic enzyme UDP-N-acetylmuramyl pentapeptide synthase encoded by the frameshifted murF gene. Simulation studies indicated an overrepresentation of poly(A) tracts in endosymbiont genomes relative to other A + T-rich bacterial genomes. Polymerase infidelity at poly(A) tracts rescues the functionality of genes with frameshift mutations and, conversely, reduces the efficiency of expression for in-frame genes carrying poly(A) regions. These features of homopolymeric tracts could be exploited to manipulate gene expression in small synthetic genomes. PMID:18815381

  9. Stepwise deletions of polyA sequences in mismatch repair-deficient colorectal cancers.

    Science.gov (United States)

    Blake, C; Tsao, J L; Wu, A; Shibata, D

    2001-05-01

    PolyA simple repeat sequence deletions are common in tumors with microsatellite instability (MSI+). Such deletions occur one base at a time in DNA mismatch repair (MMR)-deficient yeast suggesting larger deletions in human MSI+ tumors represent multiple sequential stepwise losses. Sum total deletions in four polyA repeats were variable (between -17 to -45 bp) in 20 sporadic MSI+ colorectal cancers. Progressive but less extensive total deletions (maximum of -12 bp) occurred in similar polyA sequences in MMR-deficient mice (mlh1-/-) up to 478 days old. PolyA repeat lengths were relatively stable but already shortened in the MMR-deficient cell line HCT116. A transgene with 26 A's transfected into HCT116 shortened an average of 3.8 bases pairs after 469 days in culture, less than average deletions of BAT25 (-5.3) or BAT26 (-9.0) in MSI+ cancers. These findings further suggest that extensive polyA deletions common in MSI+ tumors likely reflect multiple stepwise smaller deletions that accumulate more than hundreds of divisions after loss of MMR.

  10. Canonical Poly(A Polymerase Activity Promotes the Decay of a Wide Variety of Mammalian Nuclear RNAs.

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    Stefan M Bresson

    2015-10-01

    Full Text Available The human nuclear poly(A-binding protein PABPN1 has been implicated in the decay of nuclear noncoding RNAs (ncRNAs. In addition, PABPN1 promotes hyperadenylation by stimulating poly(A-polymerases (PAPα/γ, but this activity has not previously been linked to the decay of endogenous transcripts. Moreover, the mechanisms underlying target specificity have remained elusive. Here, we inactivated PAP-dependent hyperadenylation in cells by two independent mechanisms and used an RNA-seq approach to identify endogenous targets. We observed the upregulation of various ncRNAs, including snoRNA host genes, primary miRNA transcripts, and promoter upstream antisense RNAs, confirming that hyperadenylation is broadly required for the degradation of PABPN1-targets. In addition, we found that mRNAs with retained introns are susceptible to PABPN1 and PAPα/γ-mediated decay (PPD. Transcripts are targeted for degradation due to inefficient export, which is a consequence of reduced intron number or incomplete splicing. Additional investigation showed that a genetically-encoded poly(A tail is sufficient to drive decay, suggesting that degradation occurs independently of the canonical cleavage and polyadenylation reaction. Surprisingly, treatment with transcription inhibitors uncouples polyadenylation from decay, leading to runaway hyperadenylation of nuclear decay targets. We conclude that PPD is an important mammalian nuclear RNA decay pathway for the removal of poorly spliced and nuclear-retained transcripts.

  11. A viral nuclear noncoding RNA binds re-localized poly(A binding protein and is required for late KSHV gene expression.

    Directory of Open Access Journals (Sweden)

    Sumit Borah

    2011-10-01

    Full Text Available During the lytic phase of infection, the gamma herpesvirus Kaposi's Sarcoma-Associated Herpesvirus (KSHV expresses a highly abundant, 1.1 kb nuclear noncoding RNA of unknown function. We observe that this polyadenylated nuclear (PAN RNA avidly binds host poly(A-binding protein C1 (PABPC1, which normally functions in the cytoplasm to bind the poly(A tails of mRNAs, regulating mRNA stability and translation efficiency. During the lytic phase of KSHV infection, PABPC1 is re-localized to the nucleus as a consequence of expression of the viral shutoff exonuclease (SOX protein; SOX also mediates the host shutoff effect in which host mRNAs are downregulated while viral mRNAs are selectively expressed. We show that whereas PAN RNA is not required for the host shutoff effect or for PABPC1 re-localization, SOX strongly upregulates the levels of PAN RNA in transient transfection experiments. This upregulation is destroyed by the same SOX mutation that ablates the host shutoff effect and PABPC1 nuclear re-localization or by removal of the poly(A tail of PAN. In cells induced into the KSHV lytic phase, depletion of PAN RNA using RNase H-targeting antisense oligonucleotides reveals that it is necessary for the production of late viral proteins from mRNAs that are themselves polyadenylated. Our results add to the repertoire of functions ascribed to long noncoding RNAs and suggest a mechanism of action for nuclear noncoding RNAs in gamma herpesvirus infection.

  12. Generalized classical, quantum and intermediate statistics and the Polya urn model

    Energy Technology Data Exchange (ETDEWEB)

    Niven, Robert K. [School of Aerospace, Civil and Mechanical Engineering, University of New South Wales at ADFA, Northcott Drive, Canberra, ACT, 2600 (Australia); Niels Bohr Institute, University of Copenhagen, Copenhagen O (Denmark)], E-mail: r.niven@adfa.edu.au; Grendar, Marian [Department of Mathematics, Faculty of Natural Sciences, Bel University, Tajovskeho 40, 974 01 Banska Bystrica (Slovakia)], E-mail: marian.grendar@savba.sk

    2009-02-02

    Generalized probability distributions for Maxwell-Boltzmann, Bose-Einstein and Fermi-Dirac statistics, with unequal source ('prior') probabilities q{sub i} for each level i, are obtained by combinatorial reasoning. For equiprobable degenerate sublevels, these reduce to those given by Brillouin in 1930, more commonly given as a statistical weight for each statistic. These distributions and corresponding cross-entropy (divergence) functions are shown to be special cases of the Polya urn model, involving neither independent nor identically distributed ('ninid') sampling. The most probable Polya distribution is shown to contain the Acharya-Swamy intermediate statistic.

  13. AtCCR4a and AtCCR4b are Involved in Determining the Poly(A) Length of Granule-bound starch synthase 1 Transcript and Modulating Sucrose and Starch Metabolism in Arabidopsis thaliana.

    Science.gov (United States)

    Suzuki, Yuya; Arae, Toshihiro; Green, Pamela J; Yamaguchi, Junji; Chiba, Yukako

    2015-05-01

    Removing the poly(A) tail is the first and rate-limiting step of mRNA degradation and apparently an effective step not only for modulating mRNA stability but also for translation of many eukaryotic transcripts. Carbon catabolite repressor 4 (CCR4) has been identified as a major cytoplasmic deadenylase in Saccharomyces cerevisiae. The Arabidopsis thaliana homologs of the yeast CCR4, AtCCR4a and AtCCR4b, were identified by sequence-based analysis; however, their role and physiological significance in plants remain to be elucidated. In this study, we revealed that AtCCR4a and AtCCR4b are localized to cytoplasmic mRNA processing bodies, which are specific granules consisting of many enzymes involved in mRNA turnover. Double mutants of AtCCR4a and AtCCR4b exhibited tolerance to sucrose application but not to glucose. The levels of sucrose in the seedlings of the atccr4a/4b double mutants were reduced, whereas no difference was observed in glucose levels. Further, amylose levels were slightly but significantly increased in the atccr4a/4b double mutants. Consistent with this observation, we found that the transcript encoding granule-bound starch synthase 1 (GBSS1), which is responsible for amylose synthesis, is accumulated to a higher level in the atccr4a/4b double mutant plants than in the control plants. Moreover, we revealed that GBSS1 has a longer poly(A) tail in the double mutant than in the control plant, suggesting that AtCCR4a and AtCCR4b can influence the poly(A) length of transcripts related to starch metabolism. Our results collectively suggested that AtCCR4a and AtCCR4b are involved in sucrose and starch metabolism in A. thaliana.

  14. The Effects of Polya's Heuristic and Diary Writing on Children's Problem Solving

    Science.gov (United States)

    Hensberry, Karina K. R.; Jacobbe, Tim

    2012-01-01

    This paper presents the results of a study that aimed at increasing students' problem-solving skills. Polya's (1985) heuristic for problem solving was used and students were required to articulate their thought processes through the use of a structured diary. The diary prompted students to answer questions designed to engage them in the phases of…

  15. Effect of Polya Problem-Solving Model on Senior Secondary School Students' Performance in Current Electricity

    Science.gov (United States)

    Olaniyan, Ademola Olatide; Omosewo, Esther O.; Nwankwo, Levi I.

    2015-01-01

    This study was designed to investigate the Effect of Polya Problem-Solving Model on Senior School Students' Performance in Current Electricity. It was a quasi experimental study of non- randomized, non equivalent pre-test post-test control group design. Three research questions were answered and corresponding three research hypotheses were tested…

  16. Relooking "Look Back": A Student's Attempt at Problem Solving Using Polya's Model

    Science.gov (United States)

    Leong, Yew Hoong; Toh, Tin Lam; Tay, Eng Guan; Quek, Khiok Seng; Dindyal, Jaguthsing

    2012-01-01

    Against the backdrop of half a century of research in mathematics problem solving, Polya's last stage is especially conspicuous--by the scarcity of research on it! Much of the research focused on the first three stages (J.M. Francisco and C.A. Maher, "Conditions for promoting reasoning in problem solving: Insights from a longitudinal…

  17. Contractions in the second polyA tract of ARX are rare, non-pathogenic polymorphisms.

    Science.gov (United States)

    Conti, Valerio; Marini, Carla; Mei, Davide; Falchi, Melania; Ferrari, Anna Rita; Guerrini, Renzo

    2011-01-01

    Aristaless related homeobox (ARX) is a transcription factor containing highly conserved octapeptide, homeobox, acidic, and aristaless domains, as well as four polyA tracts. The most frequent ARX mutation found to date in patients with X-linked infantile spasms, Partington syndrome or X-linked mental retardation, is a duplication of 24 bp in exon 2, resulting in the expansion of the second polyA tract. Although the pathogenic role of this expansion has been well characterized, the effect of contractions in the same polyA tract is still debated since different reports have associated contractions to either mental retardation or a normal phenotype. Here, we report two unrelated girls with epilepsy and mental retardation who inherited from their unaffected parents, of either sex, a deletion of 24 bp (c.441_464del), resulting in a contraction of eight alanines in the second polyA tract of ARX. Segregation studies revealed the c.441_464del also in two healthy relatives of one of the patients. This finding supports the hypothesis that this contraction represents a rare, benign polymorphism. Copyright © 2010 Wiley-Liss, Inc.

  18. Students' Errors in Solving the Permutation and Combination Problems Based on Problem Solving Steps of Polya

    Science.gov (United States)

    Sukoriyanto; Nusantara, Toto; Subanji; Chandra, Tjang Daniel

    2016-01-01

    This article was written based on the results of a study evaluating students' errors in problem solving of permutation and combination in terms of problem solving steps according to Polya. Twenty-five students were asked to do four problems related to permutation and combination. The research results showed that the students still did a mistake in…

  19. Using Polya to Foster a Classroom Environment for Real-World Problem Solving.

    Science.gov (United States)

    Masingila, Joanna O.; Moellwald, Francisco Egger

    1993-01-01

    Presents a model that relates Polya's ideas on problem solving to teaching practices that help create a mathematics learning environment in which students are actively involved in doing mathematics. Illustrates the model utilizing a high school geometry problem that asks students to measure the width of a river. (MDH)

  20. Mathematics in the Making: Mapping Verbal Discourse in Polya's "Let Us Teach Guessing" Lesson

    Science.gov (United States)

    Truxaw, Mary P.; DeFranco, Thomas C.

    2007-01-01

    This paper describes a detailed analysis of verbal discourse within an exemplary mathematics lesson--that is, George Polya teaching in the Mathematics Association of America [MAA] video classic, "Let Us Teach Guessing" (1966). The results of the analysis reveal an inductive model of teaching that represents recursive cycles rather than linear…

  1. The Implementation of the Polya Method in Solving Euclidean Geometry Problems

    Science.gov (United States)

    In'am, Akhsanul

    2014-01-01

    This research is aimed at analyzing the solutions of Euclidean Geometry problems using the Polya method. This present study was made through qualitative and quantitative approaches with 85 respondents of the second semester students at the Department of Mathematics Education, University of Muhammadiyah Malang Indonesia, in the 2012/2013 academic…

  2. An Appropriate Prompts System Based on the Polya Method for Mathematical Problem-Solving

    Science.gov (United States)

    Lee, Chien I.

    2017-01-01

    Current mathematics education emphasizes techniques, formulas, and procedures, neglecting the importance of understanding, presentation, and reasoning. This turns students into passive listeners that are well-practiced only in using formulas that they do not understand. We therefore adopted the Polya problem-solving method to provide students with…

  3. Mathematics in the Making: Mapping Verbal Discourse in Polya's "Let Us Teach Guessing" Lesson

    Science.gov (United States)

    Truxaw, Mary P.; DeFranco, Thomas C.

    2007-01-01

    This paper describes a detailed analysis of verbal discourse within an exemplary mathematics lesson--that is, George Polya teaching in the Mathematics Association of America [MAA] video classic, "Let Us Teach Guessing" (1966). The results of the analysis reveal an inductive model of teaching that represents recursive cycles rather than linear…

  4. Tail gut cyst.

    Science.gov (United States)

    Rao, G Mallikarjuna; Haricharan, P; Ramanujacharyulu, S; Reddy, K Lakshmi

    2002-01-01

    The tail gut is a blind extension of the hindgut into the tail fold just distal to the cloacal membrane. Remnants of this structure may form tail gut cyst. We report a 14-year-old girl with tail gut cyst that presented as acute abdomen. The patient recovered after cyst excision.

  5. LINE-1-derived poly(A) microsatellites undergo rapid shortening and create somatic and germline mosaicism in mice.

    Science.gov (United States)

    Grandi, Fiorella C; Rosser, James M; An, Wenfeng

    2013-03-01

    Interspersed and tandem repeat sequences comprise the bulk of mammalian genomes. Interspersed repeats result from successive replication by transposable elements, such as Alu and long interspersed element type 1 (L1). Microsatellites are tandem repeats of 1-6 base pairs, among which poly(A) microsatellites are the most abundant in the human genome. The rise and fall of a microsatellite has been depicted as a life cycle. Previous studies have demonstrated that Alu and L1 insertions are a major source of A-rich microsatellites owing to the concurrent formation of a poly(A) DNA tract at the 3'-end of each insertion. The fate of such poly(A) tracts has been studied by surveying the length distribution of genomic resident Alu and L1 insertions. However, these cross-sectional studies provide no information about the tempo of mutation immediately after birth. In this study, de novo L1 insertions were created using a transgenic L1 mouse model and traced through generations to investigate the early life of poly(A) microsatellites. High frequencies of intra-individual and intergenerational shortening were observed for long poly(A) tracts, creating somatic and germline mosaicism at the insertion site, whereas little variation was observed for short poly(A) alleles. As poly(A) microsatellites are the major intrinsic signal for nucleosome positioning, their remarkable abundance and variability make them a significant source of epigenetic variation. Thus, the birth of poly(A) microsatellites from retrotransposons and the subsequent rapid and variable shortening represent a new way with which retrotransposons can modify the genetic and epigenetic architecture of our genome.

  6. Molecular recognition of single-stranded RNA: neomycin binding to poly(A).

    Science.gov (United States)

    Xi, Hongjuan; Gray, David; Kumar, Sunil; Arya, Dev P

    2009-07-01

    Poly(A) is a relevant sequence in cell biology due to its importance in mRNA stability and translation initiation. Neomycin is an aminoglycoside antibiotic that is well known for its ability to target various nucleic acid structures. Here it is reported that neomycin is capable of binding tightly to a single-stranded oligonucleotide (A(30)) with a K(d) in the micromolar range. CD melting experiments support complex formation and indicate a melting temperature of 47 degrees C. The poly(A) duplex, which melts at 44 degrees C (pH 5.5), was observed to melt at 61 degrees C in the presence of neomycin, suggesting a strong stabilization of the duplex by the neomycin.

  7. PATACSDB—the database of polyA translational attenuators in coding sequences

    Directory of Open Access Journals (Sweden)

    Malgorzata Habich

    2016-02-01

    Full Text Available Recent additions to the repertoire of gene expression regulatory mechanisms are polyadenylate (polyA tracks encoding for poly-lysine runs in protein sequences. Such tracks stall the translation apparatus and induce frameshifting independently of the effects of charged nascent poly-lysine sequence on the ribosome exit channel. As such, they substantially influence the stability of mRNA and the amount of protein produced from a given transcript. Single base changes in these regions are enough to exert a measurable response on both protein and mRNA abundance; this makes each of these sequences a potentially interesting case study for the effects of synonymous mutation, gene dosage balance and natural frameshifting. Here we present PATACSDB, a resource that contain a comprehensive list of polyA tracks from over 250 eukaryotic genomes. Our data is based on the Ensembl genomic database of coding sequences and filtered with algorithm of 12A-1 which selects sequences of polyA tracks with a minimal length of 12 A’s allowing for one mismatched base. The PATACSDB database is accessible at: http://sysbio.ibb.waw.pl/patacsdb. The source code is available at http://github.com/habich/PATACSDB, and it includes the scripts with which the database can be recreated.

  8. PolyA deletions in hereditary nonpolyposis colorectal cancer: mutations before a gatekeeper.

    Science.gov (United States)

    Kim, Kyoung-Mee; Salovaara, Reijo; Mecklin, Jukka-Pekka; Järvinen, Heikki J; Aaltonen, Lauri A; Shibata, Darryl

    2002-04-01

    Microsatellite instability (MSI) secondary to loss of DNA mismatch repair (MMR) is present in adenomas and colorectal carcinomas from individuals with hereditary nonpolyposis colorectal cancer (HNPCC). To better characterize when MMR loss occurs during HNPCC progression, the extent of deletions in noncoding polyA sequences were compared between 6 adenomas (all polyA deletions are stepwise. Adenoma deletions were nearly the same (85%) as the cancers with sum total deletions at four different polyA loci of -32.7 bases in adenomas and -38.4 bases in cancers. Intervals between negative clinical examinations and tumor removal (average of 2.1 years) were known for six tumors. There were no significant differences in the extent of deletions in tumors removed under clinical surveillance (-34.8 bases) versus tumors removed without prior negative examinations (-36.5 bases). These findings illustrate that MSI is extensive in both small adenomas, and tumors which appear after negative clinical examinations, consistent with an early loss of MMR in HNPCC, even before a gatekeeper mutation.

  9. Poly(A)-tail profiling reveals an embryonic switch in translational control

    Science.gov (United States)

    Subtelny, Alexander O.; Eichhorn, Stephen W.; Chen, Grace R.; Sive, Hazel; Bartel, David P.

    2014-04-01

    Poly(A) tails enhance the stability and translation of most eukaryotic messenger RNAs, but difficulties in globally measuring poly(A)-tail lengths have impeded greater understanding of poly(A)-tail function. Here we describe poly(A)-tail length profiling by sequencing (PAL-seq) and apply it to measure tail lengths of millions of individual RNAs isolated from yeasts, cell lines, Arabidopsis thaliana leaves, mouse liver, and zebrafish and frog embryos. Poly(A)-tail lengths were conserved between orthologous mRNAs, with mRNAs encoding ribosomal proteins and other `housekeeping' proteins tending to have shorter tails. As expected, tail lengths were coupled to translational efficiencies in early zebrafish and frog embryos. However, this strong coupling diminished at gastrulation and was absent in non-embryonic samples, indicating a rapid developmental switch in the nature of translational control. This switch complements an earlier switch to zygotic transcriptional control and explains why the predominant effect of microRNA-mediated deadenylation concurrently shifts from translational repression to mRNA destabilization.

  10. PolyA PCR amplification of cDNA from RNA extracted from formalin-fixed paraffin-embedded tissue.

    Science.gov (United States)

    Byers, Richard; Roebuck, Jamie; Sakhinia, Ebrahim; Hoyland, Judith

    2004-09-01

    RNA extraction still relies almost exclusively on the use of fresh or frozen tissue, limiting the number of samples that can be analyzed, and there is a growing need for means of global mRNA analysis of archived formalin-fixed paraffin-embedded tissue (FFPET). Previous reports of RNA extraction and amplification from FFPET are limited and do not enable global cDNA amplification. This study used polyA PCR to generate globally amplified cDNA from RNA extracted from formalin-fixed paraffin-embedded samples. RNA was extracted from nine routinely processed archival FFPET samples (lymph node, nasopharynx, prostate, lung and bone marrow) using an Ambion Paraffin Block RNA Isolation Kit. Global cDNA was generated by polyA RT-PCR and used in GAPDH specific PCR and PCR for CD33, c-myb, and SNF2. PolyA cDNA was reamplified by polyA PCR and the reamplified cDNA also used in GAPDH PCR. RNA was extracted from all nine samples, but was degraded. PolyA RT-PCR generated cDNA from all samples and was positive for GAPDH PCR in seven. PCR for CD33, c-myb, and SNF2 was positive in all samples tested. Following reamplification, the polyA cDNA remained positive for GAPDH by PCR. The results demonstrate the feasibility of globally amplifying RNA isolated from archival FFPET samples using polyA RT-PCR, which generates a renewable cDNA pool that can be probed for any cDNA species and reamplified as necessary.

  11. Heavy tails of OLS

    DEFF Research Database (Denmark)

    Mikosch, Thomas Valentin; de Vries, Casper

    2013-01-01

    Suppose the tails of the noise distribution in a regression exhibit power law behavior. Then the distribution of the OLS regression estimator inherits this tail behavior. This is relevant for regressions involving financial data. We derive explicit finite sample expressions for the tail...

  12. Pembelajaran Berbasis Masalah Berdasarkan Langkah - Langkah Polya untuk Meningkatkan Kemampuan Menyelesaikan Soal Cerita Matematika

    Directory of Open Access Journals (Sweden)

    Hilyatin Nisak Sam

    2016-02-01

    Full Text Available Tujuan penelitian ini adalah untuk mendeskripsikan pembelajaran berbasis masalah berdasarkan langkah-langkah pemecahan masalah Polya yang dapat meningkatkan kemampuan menyelesaikan soal cerita matematika siswa kelas 8 SMPN 4 Malang. Data penelitian diperoleh dari analisis lembar jawaban tes, lembar observasi, lembar catatan lapangan, dan pedoman wawancara. Hasil penelitian menunjukkan bahwa pembelajaran berbasis masalah berdasarkan langkah-langkah pemecahan masalah Polya yang dapat  meningkatkan kemampuan menyelesaikan soal cerita matematika siswa kelas 8 adalah 1 mengenalkan siswa pada masalah, 2 mengorganisasi siswa untuk belajar, 3 membantu investigasi mandiri dan kelompok dengan menggunakan langkah-langkah pemecahan masalah Polya, yaitu a memahami masalah, b menyusun rencana, c melaksanakan rencana, dan d mengecek kembali, 4 mengembangkan dan mempresentasikan hasil karya, dan 5 menganalisis dan mengevaluasi proses pemecahan masalah.The purpose of this study was to describe the problem-based learning by Polya’s steps problem solving that can improve math word problem solving grade 8 SMPN 4 Malang. Data were obtained from the analysis of the test answer sheets, observation sheets, sheets of field notes, and the questionnaires. The results showed that the problem-based learning by Polya’s steps problem solving that can improve student math story problems completion of grade 8 are 1 to introduce students to the problem, 2 organize the students to learn, 3 helping independent investigation and groups using the Polya’s steps problem solving, namely a understand the problem, b devise a plan, c carry out the plan, and d look back, 4 develop and present work, and 5 analyze and evaluate the problem-solving process.

  13. Expansion of the first PolyA tract of ARX causes infantile spasms and status dystonicus.

    Science.gov (United States)

    Guerrini, R; Moro, F; Kato, M; Barkovich, A J; Shiihara, T; McShane, M A; Hurst, J; Loi, M; Tohyama, J; Norci, V; Hayasaka, K; Kang, U J; Das, S; Dobyns, W B

    2007-07-31

    ARX is a paired-type homeobox gene located on the X chromosome that contains five exons with four polyalanine (PolyA) tracts, a homeodomain, and a conserved C-terminal aristaless domain. Studies in humans have demonstrated remarkable pleiotropy: malformation phenotypes are associated with protein truncation mutations and missense mutations in the homeobox; nonmalformation phenotypes, including X-linked infantile spasms (ISS), are associated with missense mutations outside of the homeobox and expansion of the PolyA tracts. To investigate the role of ARX, we performed mutation analysis in 115 boys with cryptogenic ISS. This included two pairs of brothers. We found an expansion of the trinucleotide repeat that codes for the first PolyA tract from 10 to 17 GCG repeats (c.333_334ins[GCG]7) in six boys (5.2%) ages 2 to 14, from four families, including the two pairs of brothers. In addition to ISS, all six boys had severe mental retardation and generalized dystonia that appeared around the age of 6 months and worsened, eventually leading to stable severe quadriplegic dyskinesia within age 2 years. Three children experienced recurrent, life-threatening status dystonicus. In four children brain MRI showed multiple small foci of abnormal cavitation on T1 and increased signal intensity on T2 in the putamina, possibly reflecting progressive multifocal loss of tissue. The phenotype of infantile spasms with severe dyskinetic quadriparesis increases the number of human disorders that result from the pathologic expansion of single alanine repeats. ARX gene testing should be considered in boys with infantile spasms and dyskinetic cerebral palsy in the absence of a consistent perinatal history.

  14. Justifying the Gompertz curve of mortality via the generalized Polya process of shocks.

    Science.gov (United States)

    Cha, Ji Hwan; Finkelstein, Maxim

    2016-06-01

    A new probabilistic model of aging that can be applied to organisms is suggested and analyzed. Organisms are subject to shocks that follow the generalized Polya process (GPP), which has been recently introduced and characterized in the literature. Distinct from the nonhomogeneous Poisson process that has been widely used in applications, the important feature of this process is the dependence of its future behavior on the number of previous events (shocks). The corresponding survival and the mortality rate functions are derived and analyzed. The general approach is used for justification of the Gompertz law of human mortality.

  15. The multivariate beta process and an extension of the Polya tree model.

    Science.gov (United States)

    Trippa, Lorenzo; Müller, Peter; Johnson, Wesley

    2011-03-01

    We introduce a novel stochastic process that we term the multivariate beta process. The process is defined for modelling-dependent random probabilities and has beta marginal distributions. We use this process to define a probability model for a family of unknown distributions indexed by covariates. The marginal model for each distribution is a Polya tree prior. An important feature of the proposed prior is the easy centring of the nonparametric model around any parametric regression model. We use the model to implement nonparametric inference for survival distributions. The nonparametric model that we introduce can be adopted to extend the support of prior distributions for parametric regression models.

  16. Interaction of phenazinium dyes with double-stranded poly(A): spectroscopy and isothermal titration calorimetry studies.

    Science.gov (United States)

    Khan, Asma Yasmeen; Saha, Baishakhi; Kumar, Gopinatha Suresh

    2014-10-15

    A comprehensive study on the binding of phenazinium dyes viz. janus green B, indoine blue, safranine O and phenosafranine with double stranded poly(A) using various spectroscopic and calorimetric techniques is presented. A higher binding of janus green B and indoine blue over safranine O and phenosafranine to poly(A) was observed from all experiments. Intercalative mode of binding of the dyes was inferred from fluorescence polarization anisotropy, iodide quenching and viscosity experiments. Circular dichroism study revealed significant perturbation of the secondary structure of poly(A) on binding of these dyes. Results from isothermal titration calorimetry experiments suggested that the binding was predominantly entropy driven with a minor contribution of enthalpy to the standard molar Gibbs energy. The results presented here may open new opportunities in the application of these dyes as RNA targeted therapeutic agents.

  17. PENGEMBANGAN PERANGKAT PEMBELAJARAN BERBASIS PROBLEM SOLVING POLYA UNTUK MENINGKATKAN KEMAMPUAN PENALARAN MATEMATIS SISWA MATERI PELUANG KELAS XI SMA

    Directory of Open Access Journals (Sweden)

    Lela Nur Safrida

    2016-04-01

    Penalaran mulai ditonjolkan dalam kurikulum matematika di seluruh dunia dan dipandang sebagai upaya utama untuk mereformasi pembelajaran matematika. Penalaran dan matematika merupakan satu kesatuan yang tidak dapat dipisahkan karena materi matematika dipahami melalui penalaran. Upaya peningkatan kemampuan penalaran matematis siswa dapat dilakukan dengan memberikan tugas yang tidak rutin. Metode pembelajaran yang mampu mengakomodasi proses berfikir dan bernalar siswa yaitu problem solving Polya. Tujuan penelitian dan pengembangan ini adalah mendeskripsikan proses dan hasil pengembangan perangkat berbasis problem solving Polya untuk siswa kelas XI pada materi permutasi dan kombinasi yang valid, praktis, dan efektif dalam meningkatkan kemampuan penalaran matematis siswa.

  18. STRATEGI PEMECAHAN MASALAH MATEMATIS VERSI GEORGE POLYA DAN PENERAPANNYA DALAM PEMBELAJARAN MATEMATIKA

    Directory of Open Access Journals (Sweden)

    Wahid Umar

    2016-05-01

    Full Text Available George Polya telah meletakan suatu warisan “pentingnya mengajar dengan pemecahan masalah”. Setiap masalah memiliki “sepuluh strategi” yang tepat dengan “empat” langkah pemecahan sesuai dengan aspek-aspek dan sudut pandangnya masing-masing di dalam menyelesaikan suatu masalah matematis. Topik ini telah menjadi komponen utama dalam kurikulum matematika pada semua tingkatan pendidikan. NCTM dalam standards (1989 mempublikasikan ”The Curriculum and Evaluations Standards for School Mathematics”, yang menekankan bahwa pemecahan masalah harus menjadi fokus dalam kurikulum matematika di sekolah. Ini berarti bahwa pemecahan masalah merupakan salah satu topik yang sangat penting dalam pembelajaran matematika. Tujuan mengajarkan matematika dengan pemecahan masalah adalah: (1 membantu guru memperbaiki keterampilan pemecahan masalah diri sendiri; (2 diberikan kepada guru untuk membantu siswa mengembangkan keterampilan pemecahan masalah mereka; (3 untuk menyelidiki strategi umum pemecahan masalah; dan (4 bagaimana membuat kata “masalah” dan “pemecahan masalah” menantang dan menarik untuk siswa. Pentingnya para siswa mengalami proses pembelajaran matematika dengan pemecahan masalah matematis. Siswa perlu dipersiapkan dan didorong untuk berpikir bahwa sesuatu itu multi-dimensi sehingga mereka dapat melihat banyak kemungkinan penyelesaian untuk suatu masalah. Dengan demikian, pemecahan masalah matematis dalam pembelajaran matematika merupakan bagian integral dari semua aktivitas matematis. Fokus kajian makalah ini adalah bagaimana strategi pemecahan masalah matematis versi George Polya dan penerapannya dalam pembelajaran matematika.

  19. Penerapan Grey-Tall and Polya Based Learning Disertai Assessment for Learning untuk Meningkatkan Kreativitas Mahasiswa

    Directory of Open Access Journals (Sweden)

    M. Zainudin

    2016-09-01

    Full Text Available Penelitian ini bertujuan untuk mendiskripsikan penerapan Gray-Tall and Polya Based Learning (GTPBL disertai Assessment for Learning (AfL yang dapat meningkatkan kreativitas mahasiswa pada matakuliah aljabar linear. Penelitian ini termasuk dalam Penelitian Tindakan Kelas (PTK, penelitian ini dilakukan di program studi pendidikan Matematika IKIP PGRI Bojonegoro selama 2 siklus. Hasil penelitian menunjukkan bahwa penerapan Gray-Tall and Polya Based Learning (GTPBL disertai Assessment for Learning (AfL yang dapat meningkatkan kreativitas mahasiswa pada matakuliah aljabar linear dilakukan dengan keaktifan dosen dalam  mengoreksi dan memberikan umpan balik hasil kinerja mahasiswa dalam membuat dan menyelesaikan permasalahan aljabar penelitian setiap pertemuan, mahasiswa pada setiap pertemuan selalu merevisi hasil kinerjanya berdasarkan masukan dari dosen dan teman sejawat, sedangkan bentuk projek yang diberikan kepada mahasiswa berupa tugas membuat permasalahan aljabar sesuai dengan materi dan menyelesaikannya dengan setidaknya 3 cara berbeda sesuai kreativitas mahasiswa. Rerata kreativitas mahasiswa berdasarkan indikator kreativitas pada aspek kefasihan dan kebaruan di siklus I lebih besar 75, tetapi pada aspek fleksibilitas hanya mencapai 70,3; sehingga belum memenuhi indikator keberhasilan. Rerata tiap indikator kreativitas mahasiswa pada siklus II lebih besar 75 sehingga memenuhi indikator keberhasilan, secara keseluruhan mahasiswa mengalami peningkatan kreativitasnya.

  20. Innovations in tailings management

    Energy Technology Data Exchange (ETDEWEB)

    Beier, N. [Alberta Univ., Devon, AB (Canada). Oil Sands Tailings Research Facility; Sego, D. [Alberta Univ., Devon, AB (Canada). Oil Sands Tailings Research Facility; Alberta Univ., Edmonton, AB (Canada). Dept. of Civil and Environmental Engineering

    2010-09-15

    This article described the coordinated research efforts at the University of Alberta's Oil Sands Tailings Research Facility (OSTRF) to address oil sands tailings management issues. The facility was established in 2003 to provide the infrastructure needed for research opportunities at the intermediate scale. To date, OSTRF has been involved in 32 separate research projects. Alberta's Energy Resources Conservation Board (ERCB) recently created Directive 74 to oblige operators to improve tailings management and document their progress on tailings at each mine site. The initial OSTRF research program focused on improving the understanding and management of the massive inventories of mature fine tailings (MFT). The research focused primarily on the geotechnical and chemical behaviour of engineered tailings and the management and treatment of process affected water (PAW). The focus on water relates to its characterization, its treatment with coke and rapid removal of water from the total tailings stream. The next phase of research to be undertaken at OSTRF will include the reduction or elimination of volatile organic carbons and greenhouse gases from tailings ponds; further development and scaling of the novel in-line tailings dewatering system and alternative methods to release water from the MFT inventory; treatment technologies for re-use of PAW in utilities and for upgrading while also developing quality standards for eventual discharge of PAW off lease; and stabilization and capping of soft tailings deposits in preparation for reclamation, including methods of dewatering the upper surface of soft tailing to enhance its strength. 1 tab., 1 fig.

  1. Bar-tailed

    NARCIS (Netherlands)

    Duijns, S.; Hidayati, N.A.; Piersma, T.

    2013-01-01

    Capsule Across the European wintering range Bar-tailed Godwits Limosa lapponica lapponica selected polychaete worms and especially Ragworms Hediste diversicolor, with differences between areas due to variations in prey availability.Aims To determine the diet of Bar-tailed Godwits across their winter

  2. ePAT: a simple method to tag adenylated RNA to measure poly(A)-tail length and other 3' RACE applications.

    Science.gov (United States)

    Jänicke, Amrei; Vancuylenberg, John; Boag, Peter R; Traven, Ana; Beilharz, Traude H

    2012-06-01

    The addition of a poly(A)-tail to the 3' termini of RNA molecules influences stability, nuclear export, and efficiency of translation. In the cytoplasm, dynamic changes in the length of the poly(A)-tail have long been recognized as reflective of the switch between translational silence and activation. Thus, measurement of the poly(A)-tail associated with any given mRNA at steady-state can serve as a surrogate readout of its translation-state. Here, we describe a simple new method to 3'-tag adenylated RNA in total RNA samples using the intrinsic property of Escherichia coli DNA polymerase I to extend an RNA primer using a DNA template. This tag can serve as an anchor for cDNA synthesis and subsequent gene-specific PCR to assess poly(A)-tail length. We call this method extension Poly(A) Test (ePAT). The ePAT approach is as efficient as traditional Ligation-Mediated Poly(A) Test (LM-PAT) assays, avoids problems of internal priming associated with oligo-dT-based methods, and allows for the accurate analysis of both the poly(A)-tail length and alternate 3' UTR usage in 3' RACE applications.

  3. The Effects of Pair Problem Solving Technique Incorporating Polya's Problem Solving Strategy on Undergraduate Students' Performance in Chemistry

    Science.gov (United States)

    Bilgin, Ibrahim

    2006-01-01

    The purpose of this study was to investigate the effects of pair problem solving technique incorporating Polya's problem solving strategy on undergraduate students' performance in conceptual and algorithmic questions in chemistry. The subjects of this study were 89 students enrolled from two first year chemistry classes. The experimental group was…

  4. Destabilization of the TAR hairpin leads to extension of the polyA hairpin and inhibition of HIV-1 polyadenylation

    NARCIS (Netherlands)

    Vrolijk, M.M.; Harwig, A.; Berkhout, B.; Das, A.T.

    2009-01-01

    ABSTRACT: BACKGROUND: Two hairpin structures that are present at both the 5' and 3' end of the HIV-1 RNA genome have important functions in the viral life cycle. The TAR hairpin binds the viral Tat protein and is essential for Tat-mediated activation of transcription. The adjacent polyA hairpin

  5. Mass spectrometric identification of proteins that interact through specific domains of the poly(A) binding protein

    DEFF Research Database (Denmark)

    Richardson, Roy; Denis, Clyde L; Zhang, Chongxu

    2012-01-01

    Poly(A) binding protein (PAB1) is involved in a number of RNA metabolic functions in eukaryotic cells and correspondingly is suggested to associate with a number of proteins. We have used mass spectrometric analysis to identify 55 non-ribosomal proteins that specifically interact with PAB1 from...

  6. A P\\'olya criterion for (strict) positive definiteness on the sphere

    CERN Document Server

    Beatson, R K; Xu, Y

    2011-01-01

    Positive definite functions are very important in both theory and applications of approximation theory, probability and statistics. In particular, identifying strictly positive definite kernels is of great interest as interpolation problems corresponding to these kernels are guaranteed to be poised. A Bochner type result of Schoenberg characterises continuous positive definite zonal functions, $f(\\cos \\cdot)$, on the sphere $\\Sdmone$, as those with nonnegative Gegenbauer coefficients. More recent results characterise strictly positive definite functions on $\\Sdmone$ by stronger conditions on the signs of the Gegenbauer coefficients. Unfortunately, given a function $f$, checking the signs of all the Gegenbauer coefficients can be an onerous, or impossible, task. Therefore, it is natural to seek simpler sufficient conditions which guarantee (strict) positive definiteness. We state a conjecture which leads to a P\\'olya type criterion for functions to be (strictly) positive definite on the sphere $\\Sdmone$. In an...

  7. Characterization of PolyA and PolyC mismatches by Raman spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Yubo Liao; Yaoyong Meng; Haodong Lei; Ying Wang

    2008-01-01

    A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na+,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.

  8. PEMECAHAN MASALAH SPASIAL MATEMATIS CALON GURU MATEMATIKA DITINJAU DARI LANGKAH-LANGKAH PEMECAHAN MASALAH POLYA

    Directory of Open Access Journals (Sweden)

    Fiki Alghadari

    2016-12-01

    Full Text Available Studi ini dilakukan untuk mengetahui kendala yang dihadapi subjek studi dalam menyelesaikan masalah spasial dengan mengaplikasikan langkah-langkah umum pemecahan masalah dari Polya. Objek studi yaitutulisan jawaban penyelesaian tes kemampuan pemecahan masalah spasial matematis yang dibuat oleh subjek. Subjek studi ini adalah tiga orangmahasiswa tahun pelajaran 2015/2016.Pengumpulan data menggunakan pendekatan kualitatif. Analisisdifokuskan pada beberapa tulisan jawaban oleh subjek. Kelemahan subjek pada kemampuan pemecahan masalah spasial terlihat pada kekeliruanberimajinasi membentuk mental image membayangkanspatial imageryatau visual imagerydalam pemikirannya,sehingga subjek perempuan gagal membuat transformasi spasialdengan benar. Kegagalan ini merupakan masalah padakemampuan visualisasi spasialdan akan berdampak pula pada gagalnya memecahkan masalah spasial. Hasil analisis yang tidak konsisten ditemukan antara analisis tes pertama dan yang kedua, karena kualitas tes memang berbeda secara spasial.

  9. Recurrence and Polya Number of General One-Dimensional Random Walks

    Institute of Scientific and Technical Information of China (English)

    张晓琨; 万晶; 陆静菊; 徐新平

    2011-01-01

    The recurrence properties of random walks can be characterized by P61ya number, i.e., the probability that the walker has returned to the origin at least once. In this paper, we consider recurrence properties for a general 1D random walk on a line, in which at each time step the walker can move to the left or right with probabilities l and r, or remain at the same position with probability o (l + r + o = 1). We calculate Polya number P of this model and find a simple expression for P as, P = 1 - △, where △ is the absolute difference of l and r (△= |l - r|). We prove this rigorous expression by the method of creative telescoping, and our result suggests that the walk is recurrent if and only if the left-moving probability l equals to the right-moving probability r.

  10. Estimating tail probabilities

    Energy Technology Data Exchange (ETDEWEB)

    Carr, D.B.; Tolley, H.D.

    1982-12-01

    This paper investigates procedures for univariate nonparametric estimation of tail probabilities. Extrapolated values for tail probabilities beyond the data are also obtained based on the shape of the density in the tail. Several estimators which use exponential weighting are described. These are compared in a Monte Carlo study to nonweighted estimators, to the empirical cdf, to an integrated kernel, to a Fourier series estimate, to a penalized likelihood estimate and a maximum likelihood estimate. Selected weighted estimators are shown to compare favorably to many of these standard estimators for the sampling distributions investigated.

  11. The Tail of BPM

    Science.gov (United States)

    Kruba, Steve; Meyer, Jim

    Business process management suites (BPMS's) represent one of the fastest growing segments in the software industry as organizations automate their key business processes. As this market matures, it is interesting to compare it to Chris Anderson's 'Long Tail.' Although the 2004 "Long Tail" article in Wired magazine was primarily about the media and entertainment industries, it has since been applied (and perhaps misapplied) to other markets. Analysts describe a "Tail of BPM" market that is, perhaps, several times larger than the traditional BPMS product market. This paper will draw comparisons between the concepts in Anderson's article (and subsequent book) and the BPM solutions market.

  12. Wagging tail vibration absorber

    Science.gov (United States)

    Barclay, R. G.; Humphrey, P. W.

    1969-01-01

    A 750-foot cantilever length of extendible-tape boom (very low stiffness) was considered as the main system to be damped. A number of tail lengths were tried from 20 feet to 80 feet after which 40 feet was investigated further as a desirable compromise between performance and practical lengths. A 40-foot damping tail produced a damping effect on the main boom for the first mode equivalent in decay rate to 3.1 percent of critical damping. In this case the spring-hinge and tail were tuned to the main boom first mode frequency and the hinge damping was set at 30 percent of critical based on the tail properties. With this same setting, damping of the second mode was .4 percent and the third mode .1 percent.

  13. Tail posture predicts tail damage among weaned piglets

    NARCIS (Netherlands)

    Zonderland, J.J.; Riel, van J.W.; Bracke, M.B.M.; Kemp, B.; Hartog, den L.A.; Spoolder, H.A.M.

    2009-01-01

    Tail biting in pigs is a widespread behavioural vice with significant animal welfare and economic consequences. All too often, tail biting is not diagnosed nor dealt with until tail damage is present. To effectively reduce the negative effects of tail biting, it must be diagnosed in an early stage.

  14. LA HOJA DE CÁLCULO PARA LA RESOLUCIÓN DE PROBLEMAS MATEMÁTICOS POR EL MÉTODO DE POLYA

    National Research Council Canada - National Science Library

    Alfonso José González Regaña

    2016-01-01

    .... En este articulo utilizamos el modelo de cuatro fases para la resolucion de problemas matematicos propuesto por George Polya, en un contexto de estudiantes de Primer curso del Grado de Educacion...

  15. The role of the poly(A) tract in the replication and virulence of tick-borne encephalitis virus

    Science.gov (United States)

    Asghar, Naveed; Lee, Yi-Ping; Nilsson, Emma; Lindqvist, Richard; Melik, Wessam; Kröger, Andrea; Överby, Anna K.; Johansson, Magnus

    2016-01-01

    The tick-borne encephalitis virus (TBEV) is a flavivirus transmitted to humans, usually via tick bites. The virus causes tick-borne encephalitis (TBE) in humans, and symptoms range from mild flu-like symptoms to severe and long-lasting sequelae, including permanent brain damage. It has been suggested that within the population of viruses transmitted to the mammalian host, quasispecies with neurotropic properties might become dominant in the host resulting in neurological symptoms. We previously demonstrated the existence of TBEV variants with variable poly(A) tracts within a single blood-fed tick. To characterize the role of the poly(A) tract in TBEV replication and virulence, we generated infectious clones of Torö-2003 with the wild-type (A)3C(A)6 sequence (Torö-6A) or with a modified (A)3C(A)38 sequence (Torö-38A). Torö-38A replicated poorly compared to Torö-6A in cell culture, but Torö-38A was more virulent than Torö-6A in a mouse model of TBE. Next-generation sequencing of TBEV genomes after passaging in cell culture and/or mouse brain revealed mutations in specific genomic regions and the presence of quasispecies that might contribute to the observed differences in virulence. These data suggest a role for quasispecies development within the poly(A) tract as a virulence determinant for TBEV in mice. PMID:27982069

  16. Effect of Zn2+ and temperature on the conformational equilibrium of single-stranded polyA in neutral solutions.

    Science.gov (United States)

    Sorokin, V A; Valeev, V A; Usenko, E L; Andrushchenko, V V

    2013-10-01

    Effect of Zn(2+) ions on the conformation of polyA in cacodilic buffer at pH 7 was investigated by differential UV spectroscopy (DUV) and by thermal denaturation. The shapes of the DUV spectra and melting curves suggest a transition of polyA into a more ordered "metallized", possibly double-helical conformation at Zn(2+) concentrations above 3×10(-5) M. A phase diagram of polyA complexes with Zn(2+) was constructed for the temperature range from 20 °C to 95 °C and Zn(2+) concentrations between 10(-5) M and 5×10(-4) M. It was found that the transition of a single strand into the "metallized" form is possible only if the length of the disordered single-stranded region becomes larger than a certain critical value, ranging between 98% and 78% as the metal concentration increases from 3×10(-5) to 5×10(-4) M. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. The Distribution of Weighted Sums of the Liouville Function and P\\'olya's Conjecture

    CERN Document Server

    Humphries, Peter

    2011-01-01

    Under the assumption of the Riemann Hypothesis, the Linear Independence Hypothesis, and a bound on negative discrete moments of the Riemann zeta function, we prove the existence of a limiting logarithmic distribution of the normalisation of the weighted sum of the Liouville function, $L_{\\alpha}(x) = \\sum_{n \\leq x}{\\lambda(n) / n^{\\alpha}}$, for $0 \\leq \\alpha < 1/2$. Using this, we conditionally show that these weighted sums have a negative bias, but that for each $0 \\leq \\alpha < 1/2$, the set of all $x \\geq 1$ for which $L_{\\alpha}(x)$ is positive has positive logarithmic density. For $\\alpha = 0$, this gives a conditional proof that the set of counterexamples to P\\'olya's conjecture has positive logarithmic density. Finally, when $\\alpha = 1/2$, we conditionally prove that $L_{\\alpha}(x)$ is negative outside a set of logarithmic density zero, thereby lending support to a conjecture of Mossinghoff and Trudgian that this weighted sum is nonpositive for all $x \\geq 17$.

  18. Structural Basis for Dimerization and Activity of Human PAPD1 a Noncanonical Poly(A) Polymerase

    Energy Technology Data Exchange (ETDEWEB)

    Y Bai; S Srivastava; J Chang; J Manley; L Tong

    2011-12-31

    Poly(A) polymerases (PAPs) are found in most living organisms and have important roles in RNA function and metabolism. Here, we report the crystal structure of human PAPD1, a noncanonical PAP that can polyadenylate RNAs in the mitochondria (also known as mtPAP) and oligouridylate histone mRNAs (TUTase1). The overall structure of the palm and fingers domains is similar to that in the canonical PAPs. The active site is located at the interface between the two domains, with a large pocket that can accommodate the substrates. The structure reveals the presence of a previously unrecognized domain in the N-terminal region of PAPD1, with a backbone fold that is similar to that of RNP-type RNA binding domains. This domain (named the RL domain), together with a {beta}-arm insertion in the palm domain, contributes to dimerization of PAPD1. Surprisingly, our mutagenesis and biochemical studies show that dimerization is required for the catalytic activity of PAPD1.

  19. Induction of antagonistic soluble decoy receptor tyrosine kinases by intronic polyA activation.

    Science.gov (United States)

    Vorlová, Sandra; Rocco, Gina; Lefave, Clare V; Jodelka, Francine M; Hess, Ken; Hastings, Michelle L; Henke, Erik; Cartegni, Luca

    2011-09-16

    Alternative intronic polyadenylation (IPA) can generate truncated protein isoforms with significantly altered functions. Here, we describe 31 dominant-negative, secreted variant isoforms of receptor tyrosine kinases (RTKs) that are produced by activation of intronic poly(A) sites. We show that blocking U1-snRNP can activate IPA, indicating a larger role for U1-snRNP in RNA surveillance. Moreover, we report the development of an antisense-based method to effectively and specifically activate expression of individual soluble decoy RTKs (sdRTKs) to alter signaling, with potential therapeutic implications. In particular, a quantitative switch from signal transducing full-length vascular endothelial growth factor receptor-2 (VEGFR2/KDR) to a dominant-negative sKDR results in a strong antiangiogenic effect both on directly targeted cells and on naive cells exposed to conditioned media, suggesting a role for this approach in interfering with angiogenic paracrine and autocrine loops. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Relooking `Look Back': a student's attempt at problem solving using Polya's model

    Science.gov (United States)

    Hoong Leong, Yew; Toh, Tin Lam; Guan Tay, Eng; Quek, Khiok Seng; Dindyal, Jaguthsing

    2012-04-01

    Against the backdrop of half a century of research in mathematics problem solving, Pólya's last stage is especially conspicuous - by the scarcity of research on it! Much of the research focused on the first three stages (J.M. Francisco and C.A. Maher, Conditions for promoting reasoning in problem solving: Insights from a longitudinal study, J. Math. Behav. 24 (2005), pp. 361-372; J.A. Taylor and C. Mcdonald, Writing in groups as a tool for non-routine problem solving in first year university mathematics, Int. J. Math. Educ. Sci. Technol. 38(5) (2007), pp. 639-655.), with little or no successful attempts at following through with the subjects. In this article, we describe a case study of how the innovation of a 'Practical Worksheet' within a new paradigm of a 'Mathematics Practical' enabled a high-achieving student to push beyond getting a solution for a problem to extending, adapting and generalizing his solution. The findings from this study indicate promise in achieving the learning of Polya's model with notable success in the fourth stage, Look Back.

  1. Structure of an Rrp6-RNA exosome complex bound to poly(A) RNA

    Energy Technology Data Exchange (ETDEWEB)

    Wasmuth, Elizabeth V.; Januszyk, Kurt; Lima, Christopher D. [MSKCC

    2014-08-20

    The eukaryotic RNA exosome processes and degrades RNA by directing substrates to the distributive or processive 3' to 5' exoribonuclease activities of Rrp6 or Rrp44, respectively. The non-catalytic nine-subunit exosome core (Exo9) features a prominent central channel. Although RNA can pass through the channel to engage Rrp44, it is not clear how RNA is directed to Rrp6 or whether Rrp6 uses the central channel. Here we report a 3.3 Å crystal structure of a ten-subunit RNA exosome complex from Saccharomyces cerevisiae composed of the Exo9 core and Rrp6 bound to single-stranded poly(A) RNA. The Rrp6 catalytic domain rests on top of the Exo9 S1/KH ring above the central channel, the RNA 3' end is anchored in the Rrp6 active site, and the remaining RNA traverses the S1/KH ring in an opposite orientation to that observed in a structure of a Rrp44-containing exosome complex. Solution studies with human and yeast RNA exosome complexes suggest that the RNA path to Rrp6 is conserved and dependent on the integrity of the S1/KH ring. Although path selection to Rrp6 or Rrp44 is stochastic in vitro, the fate of a particular RNA may be determined in vivo by the manner in which cofactors present RNA to the RNA exosome.

  2. Managing 'tail liability'.

    Science.gov (United States)

    Frese, Richard C; Weber, Ryan J

    2013-11-01

    To reduce and control their level of tail liability, hospitals should: Utilize a self-insurance vehicle; Consider combined limits between the hospital and physicians; Communicate any program changes to the actuary, underwriter, and auditor; Continue risk management and safety practices; Ensure credit is given to the organization's own medical malpractice program.

  3. Estimation of Jump Tails

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Todorov, Victor

    We propose a new and flexible non-parametric framework for estimating the jump tails of Itô semimartingale processes. The approach is based on a relatively simple-to-implement set of estimating equations associated with the compensator for the jump measure, or its "intensity", that only utilizes ...

  4. On tails of perpetuities

    CERN Document Server

    Hitczenko, Pawel

    2011-01-01

    We establish an upper bound on the tails of a random variable that arises as a solution of a stochastic difference equation. In the non--negative case our bound is similar to a lower bound obtained by Goldie and Gr\\"ubel in 1996.

  5. Poly(A) polymerase I participates in the indole regulatory pathway of Pantoea agglomerans YS19.

    Science.gov (United States)

    Li, Zihua; Jiang, Jing; Yu, Xuemei; Wu, Cunxiang; Shen, Delong; Feng, Yongjun

    2017-02-01

    Pantoea agglomerans YS19 is a preponderant endophytic bacterium isolated from rice. It is characterized by the formation of symplasmata, a type of multicellular aggregate structure, contributing to a strong stress resistance and specific adaptation of YS19 in endophyte-host associations. Indole is an important signal molecule in intra- or interspecies relationships, regulating a variety of bacterial behaviours such as cell aggregation and stress resistance; however, the regulatory mechanism remains an ongoing area of investigation. This study selected YS19 as a model strain to construct a mutant library, utilizing the mTn5 transposon mutagenesis method, thus obtaining a positive mutant with an indole-inhibited mutation gene. Via thermal asymmetric interlaced PCR, the mutational site was identified as the gene of pcnB, which encodes the poly(A) polymerase I to catalyse the polyadenylation of RNAs. The full length of the pcnB sequence was 1332 bp, and phylogenetic analysis revealed that pcnB is extremely conserved among strains of P. agglomerans. The expression of the gene was significantly inhibited (by 36.6 % as detected via quantitative PCR) by indole (0.5 mM). Many physiological behaviours of YS19 were affected by this mutation: the cell decay rate in the post-stationary growth phase was promoted, symplasmata formation and motility were inhibited in the late stationary growth phase and the colonization ability and growth-promoting effect of YS19 on the host plant were also inhibited. This study discusses the indole regulatory pathways from the point of RNA post-transcriptional modification, thus enriching our knowledge of polyadenylation and expanding current research ideas of indole regulation.

  6. Injurious tail biting in pigs

    DEFF Research Database (Denmark)

    D'Eath, R.B.; Amott, G.; Turner, S. P.

    2014-01-01

    not allow tail docking at all. Against this background, using a novel approach focusing on research where tail injuries were quantified, we review the measures that can be used to control tail biting in pigs without tail docking. Using this strict criterion, there was good evidence that manipulable...... substrates and feeder space affect damaging tail biting. Only epidemiological evidence was available for effects of temperature and season, and the effect of stocking density was unclear. Studies suggest that group size has little effect, and the effects of nutrition, disease and breed require further...

  7. Efferent loop small intestinal vitamin D receptor concentration and bone mineral density after Billroth II (Polya) gastrectomy in humans.

    Science.gov (United States)

    Pazianas, M; Zaidi, M; Subhani, J M; Finch, P J; Ang, L; Maxwell, J D

    2003-04-01

    Animal studies have demonstrated that the highest concentration of vitamin D receptors (and greatest capacity for active calcium absorption) occurs in the proximal duodenum. By passing the duodenum following Polya/Billroth II gastrectomy could result in the development of a metabolic bone disease and low bone mineral density (BMD). We thus compared the vitamin D receptor (VDR) concentration in mucosal biopsies taken at endoscopy from two functionally corresponding areas of the small intestine: the jejunum (or efferent loop) in 21 patients with a history of Polya/Billroth II gastrectomy and the second part of the duodenum in age/sex-matched control subjects. We also measured the BMD by dual energy X-ray absorptiometry. The mean VDR concentration was not significantly different between the two groups (patients vs controls, fmol/mg protein, mean +/- SE: 34.99 +/- 2.57 vs 34.67 +/- 3.71; P = 0.22), even when subgrouped as males (36.22 +/- 3.16 vs 31.2 +/- 4.24; P = 0.351) or females (31.93 +/- 4.7 vs 43 +/- 6.76; P = 0.193). In Polya/Billroth II gastrectomy patients, the VDR concentration in the efferent loop declined with age (r = -0.78, P = 0.02). In the same group, BMD, as compared with matched controls, was significantly reduced at the lumbar spine (Z-score: patients vs controls: -1.138 vs 0.099, P = 0.01), but not at the femoral neck (Z-score: -0.69 vs 0.7, P = 0.084). There was no correlation between VDR and time since operation or BMD. These results suggest that following Polya/Billroth II gastrectomy, the functional capacity of the jejunal efferent loop in reference to VDR concentration is similar to that of the second part of the duodenum in normal subjects. Therefore, the reduced BMD in our patients, also a common finding in other studies, may not be secondary to the reduced capacity of the VDR system that facilitates the active calcium transport pathway in the proximal small intestine.

  8. Identification of Endogenous mRNA-Binding Proteins in Yeast Using Crosslinking and PolyA Enrichment.

    Science.gov (United States)

    Mitchell, Sarah F; Parker, Roy

    2016-01-01

    The maturation, localization, stability, and translation of messenger RNAs (mRNAs) are regulated by a wide variety of mRNA-binding proteins. Identification of the complete set of mRNA-binding proteins is a key step in understanding the regulation of gene expression. Herein, we describe a method for identifying yeast mRNA-binding proteins in a systematic manner using UV crosslinking, purification of polyA(+) mRNAs under denaturing conditions, and mass spectrometry to identify covalently bound proteins.

  9. In vivo cross-linking followed by polyA enrichment to identify yeast mRNA binding proteins.

    Science.gov (United States)

    Mitchell, Sarah F; Parker, Roy

    2015-01-01

    mRNA binding proteins regulate gene expression by controlling the processing, localization, decay, and translation of messenger RNAs (mRNAs). To fully understand this process, it is necessary to identify the complete set of mRNA binding proteins. This work describes a method for the systematic identification of yeast mRNA binding proteins. This method applies in vivo UV cross-linking, affinity pull-down of polyA(+) mRNAs, and analysis by mass spectrometry to identify proteins that directly bind to mRNAs.

  10. Somatic Deletions of the PolyA Tract in the 3′ Untranslated Region of Epidermal Growth Factor Receptor Are Common in Microsatellite Instability–High Endometrial and Colorectal Carcinomas

    Science.gov (United States)

    Ma, Deqin; Chen, Zhao; Nero, Christopher; Patel, Keyur P.; Daoud, Emad M.; Cheng, Hanyin; Djordjevic, Bojana; Broaddus, Russell R.; Medeiros, L. Jeffrey; Rashid, Asif; Luthra, Rajyalakshmi

    2013-01-01

    Context Epidermal growth factor receptor (EGFR) is overexpressed in up to 80% of colorectal and endometrial carcinomas. Deletions of the polyA tract in the 3′ untranslated region (3′ UTR) have been reported in microsatellite instability–high (MSI-H) colonic carcinomas, but their impacts on EGFR expression and downstream pathways are unclear. This phenomenon has not been reported in other MSI-H tumors. Objective To assess the 3′ UTR polyA tract of EGFR in both endometrial and colorectal carcinomas and the mutational status of EGFR downstream pathways. Design Ninety-eight colorectal carcinomas and 47 endometrial carcinomas were included. EGFR 3′ UTR polyA status was detected by capillary electrophoresis and Sanger sequencing. EGFR gene expression, EGFR copy numbers, and KRAS and BRAF mutation status were analyzed accordingly. Results The 3′ UTR polyA tract was deleted in 18 of 23 (78%) MSI-H versus 0 of 24 microsatellite-stable endometrial carcinomas (P polyA deletions versus those with wild-type polyA tract. Amplification of the EGFR gene was not observed. Deletions in polyA tract do not seem to affect the frequency of KRAS and BRAF mutations. Conclusions Deletions of EGFR 3′ UTR polyA are frequent in endometrial and colorectal carcinomas, are confined almost exclusively to MSI-H tumors, and do not affect KRAS and BRAF mutations. PMID:22540299

  11. Somatic deletions of the polyA tract in the 3' untranslated region of epidermal growth factor receptor are common in microsatellite instability-high endometrial and colorectal carcinomas.

    Science.gov (United States)

    Deqin, Ma; Chen, Zhao; Nero, Christopher; Patel, Keyur P; Daoud, Emad M; Cheng, Hanyin; Djordjevic, Bojana; Broaddus, Russell R; Medeiros, L Jeffrey; Rashid, Asif; Luthra, Rajyalakshmi

    2012-05-01

    Epidermal growth factor receptor (EGFR) is overexpressed in up to 80% of colorectal and endometrial carcinomas. Deletions of the polyA tract in the 3' untranslated region (3' UTR) have been reported in microsatellite instability-high (MSI-H) colonic carcinomas, but their impacts on EGFR expression and downstream pathways are unclear. This phenomenon has not been reported in other MSI-H tumors. To assess the 3' UTR polyA tract of EGFR in both endometrial and colorectal carcinomas and the mutational status of EGFR downstream pathways. Ninety-eight colorectal carcinomas and 47 endometrial carcinomas were included. EGFR 3' UTR polyA status was detected by capillary electrophoresis and Sanger sequencing. EGFR gene expression, EGFR copy numbers, and KRAS and BRAF mutation status were analyzed accordingly. The 3' UTR polyA tract was deleted in 18 of 23 (78%) MSI-H versus 0 of 24 microsatellite-stable endometrial carcinomas (P polyA deletions versus those with wild-type polyA tract. Amplification of the EGFR gene was not observed. Deletions in polyA tract do not seem to affect the frequency of KRAS and BRAF mutations. Deletions of EGFR 3' UTR polyA are frequent in endometrial and colorectal carcinomas, are confined almost exclusively to MSI-H tumors, and do not affect KRAS and BRAF mutations.

  12. PROSES BERPIKIR SISWA SEKOLAH MENENGAH PERTAMA DALAM MEMECAHKAN MASALAH MATEMATIKA BERDASARKAN LANGKAH-LANGKAH POLYA DITINJAU DARI ADVERSITY QUOTIENT

    Directory of Open Access Journals (Sweden)

    Muhammad Yani

    2016-06-01

    Full Text Available Penelitian ini dilakukan untuk menjelaskan proses berpikir dan menganalisis kesulitan siswa dalam memecahkan masalah matematika berdasarkan pengukuran Polya ditinjau dari Adversity Quotient (AQ. Penelitian ini merupakan penelitian deskirptif kualitatif dengan subjek penelitian adalah siswa dari kelas IX SMP N 1 Banda Aceh tediri dari tiga siswa. Pemilihan subjek penelitian menggunakan metode purposive sampling dan berdasarkan tingkatan AQ (climber, camper, dan quitter dan komunikasi (lisan dan tertulis. Pengumpulan data menggunakan wawancara berbasis tugas, dan triangulasi untuk mengecek validitas data. Data dianalisis menggunakan konsep dari Miles dan Huberman: yaitu tahap pengurangan data, presentasi data, dan kesimpulan. Hasil menunjukkan bahwa: (1 Proses berpikir dari subjek climber yaitu secara asimilasi dalam memahami, merencanakan penyelesaian, .serta mengecek kembali; (2 Subjek camper juga berpikir secara asimilasi pada tahap memahami masalah, merencanakan penyelesaian, dan mengecek kembali; (3 subjek quitter berpikir secara akomodasi dalam memahami masalah dan menyelesaikan masalah. Kata kunci: Proses Berpikir, Pemecahan Masalah, Tahap Polya, Adversity Quotient (AQ DOI: http://dx.doi.org/10.22342/jpm.10.1.3278.42-57

  13. PolyA RT-PCR-based quantification of microRNA by using universal TaqMan probe.

    Science.gov (United States)

    Luo, Xin; Zhang, Jin; Wang, Huijun; Du, Yingying; Yang, Lu; Zheng, Fengyun; Ma, Duan

    2012-04-01

    Quantification of microRNAs (miRNAs) in tissues under normal and pathological conditions is important for elucidating miRNA functions. Based on a PolyA RT-PCR method we have described (J Zhang et al. Biochem Biophys Res Commun 2008 377:136-140), a modified miRNA quantification method was developed and validated using a universal TaqMan probe complementary to the reverse transcript primer. This method effectively detects miRNA expression in cell lines and tissues. The TaqMan probe is more accurate and reliable than the SYBR Green method since it was free from primer dimers. A series of miRNAs were tested in five different mouse tissues: the method differentiated different miRNAs of the same family. This universal TaqMan probe-based PolyA RT-PCR method showed its advantages in precision, simplicity and high-throughput capability compared with other miRNA-detecting methods.

  14. Analysis of poly(A + RNA distribution during maize somatic embryogenesis using digoxigenated oligo-dT probes

    Directory of Open Access Journals (Sweden)

    R. Bimal

    2014-01-01

    Full Text Available The pattern of total transcription activity in terms of steady state levels of poly(A+ containing mRNA during callus initiation and somatic embryogenesis in a high (A188 and a low (A632 embryogenic line of maize was analyzed using digoxigenin labelled oligo-dT probes. A gradual increase and a preferential accumulation of label was observed in both lines, differing temporally up to 4 days in culture. In the A188 line of maize the callus gave rise to somatic embryos. The globular embryos showed less label than the callus; this labelling was mostly present in the basal part of the embryos. At a later stage upper embryogenic and lower non-embryogenic layers were observed in the A188 callus, showing conspicuous differences in the amount of label. In the late globular stage the poly(A+ RNA signals were seen all over the embryo but at the junction of the suspensor and the callus tissue no label was observed.

  15. Destabilization of the TAR hairpin leads to extension of the polyA hairpin and inhibition of HIV-1 polyadenylation.

    Science.gov (United States)

    Vrolijk, Martine M; Harwig, Alex; Berkhout, Ben; Das, Atze T

    2009-02-11

    Two hairpin structures that are present at both the 5' and 3' end of the HIV-1 RNA genome have important functions in the viral life cycle. The TAR hairpin binds the viral Tat protein and is essential for Tat-mediated activation of transcription. The adjacent polyA hairpin encompasses the polyadenylation signal AAUAAA and is important for the regulation of polyadenylation. Specifically, this RNA structure represses polyadenylation at the 5' side, and enhancer elements on the 3' side overcome this suppression. We recently described that the replication of an HIV-1 variant that does not need TAR for transcription was severely impaired by destabilization of the TAR hairpin, even though a complete TAR deletion was acceptable. In this study, we show that the TAR-destabilizing mutations result in reduced 3' polyadenylation of the viral transcripts due to an extension of the adjacent polyA hairpin. Thus, although the TAR hairpin is not directly involved in polyadenylation, mutations in TAR can affect this process. The stability of the HIV-1 TAR hairpin structure is important for the proper folding of the viral RNA transcripts. This study illustrates how mutations that are designed to study the function of a specific RNA structure can change the structural presentation of other RNA domains and thus affect viral replication in an indirect way.

  16. Telling tails: selective pressures acting on investment in lizard tails.

    Science.gov (United States)

    Fleming, Patricia A; Valentine, Leonie E; Bateman, Philip W

    2013-01-01

    Caudal autotomy is a common defense mechanism in lizards, where the animal may lose part or all of its tail to escape entrapment. Lizards show an immense variety in the degree of investment in a tail (i.e., length) across species, with tails of some species up to three or four times body length (snout-vent length [SVL]). Additionally, body size and form also vary dramatically, including variation in leg development and robustness and length of the body and tail. Autotomy is therefore likely to have fundamentally different effects on the overall body form and function in different species, which may be reflected directly in the incidence of lost/regenerating tails within populations or, over a longer period, in terms of relative tail length for different species. We recorded data (literature, museum specimens, field data) for relative tail length (n=350 species) and the incidence of lost/regenerating tails (n=246 species). We compared these (taking phylogeny into account) with intrinsic factors that have been proposed to influence selective pressures acting on caudal autotomy, including body form (robustness, body length, leg development, and tail specialization) and ecology (foraging behavior, physical and temporal niches), in an attempt to identify patterns that might reflect adaptive responses to these different factors. More gracile species have relatively longer tails (all 350 spp., P lizards (all 246 spp., P < 0.01; Scindidae, P < 0.05), larger skinks (P < 0.05), climbing geckos (P < 0.05), or active-foraging iguanids (P < 0.05). The selective advantage of investing in a relatively longer tail may be due to locomotor mechanics, although the patterns observed are also largely consistent with predictions based on predation pressure.

  17. Uranium mill tailings and radon

    Energy Technology Data Exchange (ETDEWEB)

    Hanchey, L A

    1981-01-01

    The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is extremely small. If the assumptions used in the studies are correct, one or two people per year in the US may develop cancer as a result of radon exhaled from all the Uranium Mill Tailings Remedial Action Program sites. The remedial action should reduce the hazard from the tailings by a factor of about 100.

  18. Oilsand tailings : solving the issues

    Energy Technology Data Exchange (ETDEWEB)

    Granson, E.

    2008-11-15

    Oilsands tailings management is an integral part of oil sands research and development. Studies to decrease land disturbance and to resolve environmental and safety issues are underway at several government agencies and industry groups, including the Alberta Energy Research Institute, the Oil Sands Tailings Research Facility and Natural Resources Canada's CANMET Advanced Separation Technologies division. Fresh tailings that come from the bitumen extraction process are composed of 85 to 90 per cent water and 10 to 15 per cent solids having the consistency of muddy water. The 3 zones that develop following discharge into the tailings ponds are 3 metres of clear water; residual hydrocarbons that float on the surface; and, a 1 metre zone of water and settling clay particles known as mature fine tailings (MFT) which comprise about 90 per cent of the volume of the tailings pond. The tailings ponds must be built in areas where there is no bitumen suitable for surface mining. The impounded area is surrounded by tailings dykes built from local overburden materials. As such, tailings ponds are managed as dams according to Alberta Dam Safety regulation requirements. Dam stability is increased by the installation of internal seepage control measures. This article described the key guidelines and objectives for the construction of tailings ponds. It also described the 3 primary types of reclamation settings, namely aquatic reclamation, wetland reclamation and terrestrial reclamation. Water removed from the MFT can be recycled back to the plant to reduce the amount of water used from the river. Although this contributes to lower energy costs, there are challenges regarding salt levels that builds up in piping and equipment. The presence of water in the tailings also prevents tailings reclamation. In addition to mechanical systems to remove water, researchers are also considering the use of chemicals and natural processes. In the consolidated tailings (CT) process, the

  19. TMV mutants with poly(A) tracts of different lengths demonstrate structural variations in 3′UTR affecting viral RNAs accumulation and symptom expression

    Science.gov (United States)

    Guo, Song; Kierzek, Elzbieta; Chen, Gang; Zhou, Yi-Jun; Wong, Sek-Man

    2015-01-01

    The upstream pseudoknots domain (UPD) of Tobacco mosaic virus (TMV) is located at the 3′-untranslated region (UTR). It plays an important role in virus replication and translation. To determine the importance of UPD and 3′-UTR, and the effects of introduced RNA elements in TMV 3′-UTR, a series of TMV mutants with internal poly(A) tract upstream of UPD was constructed for structural analysis by selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE). TMV(24A+UPD) and TMV(42A+UPD) formed a similar structure as that of TMV 3′-UTR, but TMV(62A+UPD) structures altered by the introduced poly(A) tract. In addition, TMV(24A+UPD) had a higher viral RNAs accumulation than TMV in N. benthamiana protoplasts, and induced lethal symptoms in the infected plants. TMV(62A+UPD) showed a drastically reduced accumulation, its coat protein was undetectable in protoplasts, and the inoculated plants remained symptomless. This study analyzed the structures of 3′-UTR of TMV and found that the longer poly(A) tract introduced upstream of UPD reduced viral RNAs accumulation and induced milder symptoms in N. benthamiana. In conclusion, different lengths of the internal poly(A) tract introduced into the TMV 3′UTR lead to structural variations that affect virus accumulation and symptom expression. PMID:26678425

  20. TMV mutants with poly(A) tracts of different lengths demonstrate structural variations in 3'UTR affecting viral RNAs accumulation and symptom expression.

    Science.gov (United States)

    Guo, Song; Kierzek, Elzbieta; Chen, Gang; Zhou, Yi-Jun; Wong, Sek-Man

    2015-12-18

    The upstream pseudoknots domain (UPD) of Tobacco mosaic virus (TMV) is located at the 3'-untranslated region (UTR). It plays an important role in virus replication and translation. To determine the importance of UPD and 3'-UTR, and the effects of introduced RNA elements in TMV 3'-UTR, a series of TMV mutants with internal poly(A) tract upstream of UPD was constructed for structural analysis by selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE). TMV(24A+UPD) and TMV(42A+UPD) formed a similar structure as that of TMV 3'-UTR, but TMV(62A+UPD) structures altered by the introduced poly(A) tract. In addition, TMV(24A+UPD) had a higher viral RNAs accumulation than TMV in N. benthamiana protoplasts, and induced lethal symptoms in the infected plants. TMV(62A+UPD) showed a drastically reduced accumulation, its coat protein was undetectable in protoplasts, and the inoculated plants remained symptomless. This study analyzed the structures of 3'-UTR of TMV and found that the longer poly(A) tract introduced upstream of UPD reduced viral RNAs accumulation and induced milder symptoms in N. benthamiana. In conclusion, different lengths of the internal poly(A) tract introduced into the TMV 3'UTR lead to structural variations that affect virus accumulation and symptom expression.

  1. Autoregulation of TDP-43 mRNA levels involves interplay between transcription, splicing, and alternative polyA site selection.

    Science.gov (United States)

    Avendaño-Vázquez, S Eréndira; Dhir, Ashish; Bembich, Sara; Buratti, Emanuele; Proudfoot, Nicholas; Baralle, Francisco E

    2012-08-01

    TDP-43 is a critical RNA-binding factor associated with pre-mRNA splicing in mammals. Its expression is tightly autoregulated, with loss of this regulation implicated in human neuropathology. We demonstrate that TDP-43 overexpression in humans and mice activates a 3' untranslated region (UTR) intron, resulting in excision of the proximal polyA site (PAS) pA(1). This activates a cryptic PAS that prevents TDP-43 expression through a nuclear retention mechanism. Superimposed on this process, overexpression of TDP-43 blocks recognition of pA(1) by competing with CstF-64 for PAS binding. Overall, we uncover complex interplay between transcription, splicing, and 3' end processing to effect autoregulation of TDP-43.

  2. Multiplex analysis of polyA-linked sequences (MAPS): an RNA-seq strategy to profile poly(A+) RNA.

    Science.gov (United States)

    Zhou, Yu; Li, Hai-Ri; Huang, Jie; Jin, Ge; Fu, Xiang-Dong

    2014-01-01

    We summarize 12 experimental methods that have been developed for profiling gene expression by focusing on the 3'-end of poly(A+) mRNA, distilling both common and unique features. Of this family of methods, we provide detailed protocol for MAPS, a method we believe is the simplest and most cost-effective for profiling gene expression and quantifying alternative polyadenylation events by oligo-dT priming followed by random priming and deep sequencing. This method also enables library multiplexing by using a set of bar coding primers during PCR amplification. We also provide a general guideline for analysis of the data generated by MAPS by using the software package maps3end.

  3. Next generation sequencing analysis of human platelet PolyA+ mRNAs and rRNA-depleted total RNA.

    Science.gov (United States)

    Kissopoulou, Antheia; Jonasson, Jon; Lindahl, Tomas L; Osman, Abdimajid

    2013-01-01

    Platelets are small anucleate cells circulating in the blood vessels where they play a key role in hemostasis and thrombosis. Here, we compared platelet RNA-Seq results obtained from polyA+ mRNA and rRNA-depleted total RNA. We used purified, CD45 depleted, human blood platelets collected by apheresis from three male and one female healthy blood donors. The Illumina HiSeq 2000 platform was employed to sequence cDNA converted either from oligo(dT) isolated polyA+ RNA or from rRNA-depleted total RNA. The reads were aligned to the GRCh37 reference assembly with the TopHat/Cufflinks alignment package using Ensembl annotations. A de novo assembly of the platelet transcriptome using the Trinity software package and RSEM was also performed. The bioinformatic tools HTSeq and DESeq from Bioconductor were employed for further statistical analyses of read counts. Consistent with previous findings our data suggests that mitochondrially expressed genes comprise a substantial fraction of the platelet transcriptome. We also identified high transcript levels for protein coding genes related to the cytoskeleton function, chemokine signaling, cell adhesion, aggregation, as well as receptor interaction between cells. Certain transcripts were particularly abundant in platelets compared with other cell and tissue types represented by RNA-Seq data from the Illumina Human Body Map 2.0 project. Irrespective of the different library preparation and sequencing protocols, there was good agreement between samples from the 4 individuals. Eighteen differentially expressed genes were identified in the two sexes at 10% false discovery rate using DESeq. The present data suggests that platelets may have a unique transcriptome profile characterized by a relative over-expression of mitochondrially encoded genes and also of genomic transcripts related to the cytoskeleton function, chemokine signaling and surface components compared with other cell and tissue types. The in vivo functional significance

  4. Mercury's Dynamic Magnetic Tail

    Science.gov (United States)

    Slavin, James A.

    2010-01-01

    The Mariner 10 and MESSENGER flybys of Mercury have revealed a magnetosphere that is likely the most responsive to upstream interplanetary conditions of any in the solar system. The source of the great dynamic variability observed during these brief passages is due to Mercury's proximity to the Sun and the inverse proportionality between reconnection rate and solar wind Alfven Mach number. However, this planet's lack of an ionosphere and its small physical dimensions also contribute to Mercury's very brief Dungey cycle, approx. 2 min, which governs the time scale for internal plasma circulation. Current observations and understanding of the structure and dynamics of Mercury's magnetotail are summarized and discussed. Special emphasis will be placed upon such questions as: 1) How much access does the solar wind have to this small magnetosphere as a function of upstream conditions? 2) What roles do heavy planetary ions play? 3) Do Earth-like substorms take place at Mercury? 4) How does Mercury's tail respond to extreme solar wind events such coronal mass ejections? Prospects for progress due to advances in the global magnetohydrodynamic and hybrid simulation modeling and the measurements to be taken by MESSENGER after it enters Mercury orbit on March 18, 2011 will be discussed.

  5. Tails, Fears and Risk Premia

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Todorov, Victor

    We show that the compensation for rare events accounts for a large fraction of the equity and variance risk premia in the S&P 500 market index. The probability of rare events vary significantly over time, increasing in periods of high market volatility, but the risk premium for tail events cannot...... solely be explained by the level of the volatil- ity. Our empirical investigations are essentially model-free. We estimate the expected values of the tails under the statistical probability measure from "medium" size jumps in high-frequency intraday prices and an extreme value theory approximation...... for the corresponding jump tail density. Our estimates for the risk-neutral expectations are based on short maturity out-of-the money options and new model-free option implied variation measures explicitly designed to separate the tail probabilities. At a general level, our results suggest that any satisfactory...

  6. White-tailed jackrabbit relocation

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This memo summarizes a plan to relocate white-tailed jackrabbits to Walnut Creek National Wildlife Refuge (Neal Smith National Wildlife Refuge) during 1997.

  7. The effects of SV40 PolyA sequence and its AATAAA signal on upstream GFP gene expression and transcription termination%SV40PolyA序列及其AATAAA信号对上游GFP基因表达及转录终止的影响

    Institute of Scientific and Technical Information of China (English)

    李书平; 冯晶晶; 王红钢; 王秀芳; 吕占军

    2012-01-01

    SV40 PolyA (Simian virus 40 PolyA, also called Poly A) sequence is DNA sequence (240 bp) that possesses the activity of transcription termination and" can add PolyA tail to mRNA. PolyA contains AATAAA hexanucleotide polyadenylation signal. Fourteen copies of Alu in sense orientation (Alul4) were inserted downstream of GFP in pEGFP-Cl to construct pAlul4 plasmid, and then HeLa cells were transiently transfected with pAlul4. Northern blot and fluorescence microscope were used to observe GFP RNA and protein expressions. Our results found that Alu tandem sequence inhibited remarkably GFP gene expression, but produced higher-molecular-mass GFP fusion RNA. PolyA and its sequence that was deleted AATAAA signal in sense or antisense orientation were inserted between GFP and Alu tandem sequence in pAlul4. The results showed that all the inserted PolyA sequences partly eliminated the inhibition induced by Alul4. PolyA sequences without AATAAA signal in sense or antisense orientation still induced transcription termination. Antisense PolyA (PolyAas) was divided into four fragments that all are 60 bp long and the middle two fragments were named 2F2R and 3F3R. 2F2R or 3F3R was inserted upstream of Alu tandem sequence in pAlul4. The molecular mass of GFP fusion RNA increased when the copy number of 2F2R increased. 2F2R can support transcription elongation when 2F2R is located upstream of other 2F2R. Nevertheless, 2F2R located upstream of Alu tandem sequence can induce transcription termination. Inserting one copy or 64 copies of 3F3R in upstream of Alu tandem sequence caused the production., of lower-molecular-mass GFP RNA.%SV40 PolyA(猴空泡病毒PolyA,简称PolyA)序列是有转录终止作用和使转录的mRNA添加PolyA尾的DNA序列(240 bp),含有AATAAA六核苷酸多腺苷化信号(Polyadenylation signal).在pEGFP-C1质粒的GFP基因下游插入14个同向串联的Alu序列(Alu14),构建pAlul4质粒,瞬时转染HeLa细胞,用Northern blot检

  8. Kinetic studies of yeast polyA polymerase indicate an induced fit mechanism for nucleotide specificity.

    Science.gov (United States)

    Balbo, Paul B; Meinke, Gretchen; Bohm, Andrew

    2005-05-31

    Polyadenylate polymerase (PAP) catalyzes the synthesis of 3'-polyadenylate tails onto mRNA. A comprehensive steady-state kinetic analysis of PAP was conducted which included initial velocity studies of the forward and reverse reactions, inhibition studies, and the use of alternative substrates. The reaction (A(n) + ATP A(n+1) + PP(i)) is adequately described by a rapid equilibrium random mechanism. Several thermodynamic parameters for the reaction were determined or calculated, including the overall equilibrium constant (K(eq) = 84) and the apparent equilibrium constant of the internal step (K(int) = 4) which involves the rate-determining interconversion of central complexes. A large (100-fold) difference in Vmax accounts for nucleotide specificity (ATP vs CTP), despite an only 3-fold difference in Km. Comparison of the sulfur elemental effect on Vmax for ATP and CTP suggests that the chemical step is rate-determining for both reactions. Comparison of the sulfur elemental effect on Vmax/Km revealed differences in the mechanism by which either nucleotide is incorporated. Consistent with these data, an induced fit mechanism for nucleotide specificity is proposed whereby PAP couples a uniform binding mechanism, which selects for ATP, with a ground-state destabilization mechanism, which serves to accelerate the velocity for the correct substrate.

  9. Does climate have heavy tails?

    Science.gov (United States)

    Bermejo, Miguel; Mudelsee, Manfred

    2013-04-01

    When we speak about a distribution with heavy tails, we are referring to the probability of the existence of extreme values will be relatively large. Several heavy-tail models are constructed from Poisson processes, which are the most tractable models. Among such processes, one of the most important are the Lévy processes, which are those process with independent, stationary increments and stochastic continuity. If the random component of a climate process that generates the data exhibits a heavy-tail distribution, and if that fact is ignored by assuming a finite-variance distribution, then there would be serious consequences (in the form, e.g., of bias) for the analysis of extreme values. Yet, it appears that it is an open question to what extent and degree climate data exhibit heavy-tail phenomena. We present a study about the statistical inference in the presence of heavy-tail distribution. In particular, we explore (1) the estimation of tail index of the marginal distribution using several estimation techniques (e.g., Hill estimator, Pickands estimator) and (2) the power of hypothesis tests. The performance of the different methods are compared using artificial time-series by means of Monte Carlo experiments. We systematically apply the heavy tail inference to observed climate data, in particular we focus on time series data. We study several proxy and directly observed climate variables from the instrumental period, the Holocene and the Pleistocene. This work receives financial support from the European Commission (Marie Curie Initial Training Network LINC, No. 289447, within the 7th Framework Programme).

  10. Saccharomyces cerevisiae Ngl3p is an active 3′–5′ exonuclease with a specificity towards poly-A RNA reminiscent of cellular deadenylases

    DEFF Research Database (Denmark)

    Feddersen, Ane; Dedic, Emil; Poulsen, Esben Guldahl

    2012-01-01

    –Endonuclease–Phosphatase (EEP) families, respectively. Ngl3p has been identified as a new member of the EEP family of exonucleases based on sequence homology, but its activity and biological roles are presently unknown. Here, we show using in vitro deadenylation assays on defined RNA species mimicking poly-A containing m......RNAs that yeast Ngl3p is a functional 3′–5′ exonuclease most active at slightly acidic conditions. We further show that the enzyme depends on divalent metal ions for activity and possesses specificity towards poly-A RNA similar to what has been observed for cellular deadenylases. The results suggest that Ngl3p...

  11. Next generation sequencing analysis of human platelet PolyA+ mRNAs and rRNA-depleted total RNA.

    Directory of Open Access Journals (Sweden)

    Antheia Kissopoulou

    Full Text Available BACKGROUND: Platelets are small anucleate cells circulating in the blood vessels where they play a key role in hemostasis and thrombosis. Here, we compared platelet RNA-Seq results obtained from polyA+ mRNA and rRNA-depleted total RNA. MATERIALS AND METHODS: We used purified, CD45 depleted, human blood platelets collected by apheresis from three male and one female healthy blood donors. The Illumina HiSeq 2000 platform was employed to sequence cDNA converted either from oligo(dT isolated polyA+ RNA or from rRNA-depleted total RNA. The reads were aligned to the GRCh37 reference assembly with the TopHat/Cufflinks alignment package using Ensembl annotations. A de novo assembly of the platelet transcriptome using the Trinity software package and RSEM was also performed. The bioinformatic tools HTSeq and DESeq from Bioconductor were employed for further statistical analyses of read counts. RESULTS: Consistent with previous findings our data suggests that mitochondrially expressed genes comprise a substantial fraction of the platelet transcriptome. We also identified high transcript levels for protein coding genes related to the cytoskeleton function, chemokine signaling, cell adhesion, aggregation, as well as receptor interaction between cells. Certain transcripts were particularly abundant in platelets compared with other cell and tissue types represented by RNA-Seq data from the Illumina Human Body Map 2.0 project. Irrespective of the different library preparation and sequencing protocols, there was good agreement between samples from the 4 individuals. Eighteen differentially expressed genes were identified in the two sexes at 10% false discovery rate using DESeq. CONCLUSION: The present data suggests that platelets may have a unique transcriptome profile characterized by a relative over-expression of mitochondrially encoded genes and also of genomic transcripts related to the cytoskeleton function, chemokine signaling and surface components

  12. Challenging the Long Tail Recommendation

    CERN Document Server

    Yin, Hongzhi; Li, Jing; Yao, Junjie; Chen, Chen

    2012-01-01

    The success of "infinite-inventory" retailers such as Amazon.com and Netflix has been largely attributed to a "long tail" phenomenon. Although the majority of their inventory is not in high demand, these niche products, unavailable at limited-inventory competitors, generate a significant fraction of total revenue in aggregate. In addition, tail product availability can boost head sales by offering consumers the convenience of "one-stop shopping" for both their mainstream and niche tastes. However, most of existing recommender systems, especially collaborative filter based methods, can not recommend tail products due to the data sparsity issue. It has been widely acknowledged that to recommend popular products is easier yet more trivial while to recommend long tail products adds more novelty yet it is also a more challenging task. In this paper, we propose a novel suite of graph-based algorithms for the long tail recommendation. We first represent user-item information with undirected edge-weighted graph and i...

  13. Effect of mutations in a simian virus 40 PolyA signal enhancer on green fluorescent protein reporter gene expression.

    Science.gov (United States)

    Wang, H G; Wang, X F; Jing, X Y; Li, Z; Zhang, Y; Lv, Z J

    2011-08-26

    Our previous studies have shown that tandem Alu repeats inhibit green fluorescent protein (GFP) gene expression when inserted downstream of the GFP gene in the pEGFP-C1 vector. We found that the 22R sequence (5'-GTGAAAAAAATGCTTTATTTGT-3') from the antisense PolyA (240 bp polyadenylation signal) of simian virus 40, eliminated repression of GFP gene expression when inserted between the GFP gene and the Alu repeats. The 22R sequence contains an imperfect palindrome; based on RNA structure software prediction, it forms an unstable stem-loop structure, including a loop, a first stem, a bulge, and a second stem. Analysis of mutations of the loop length of the 22R sequence showed that the three-nucleotide loop (wild-type, 22R) induced much stronger GFP expression than did other loop lengths. Two mutations, 4TMI (A7→T, A17→T) and 5AMI (A6→T, T18→A), which caused the base type changes in the bulge and in the second stem in the 22R sequence, induced stronger GFP gene expression than 22R itself. Mutation of the bulge base (A17→T), leading to complete complementation of the stem, caused weaker GFP gene expression. Sequences without a palindrome (7pieA, 5'-GTGAAAAAAATG CAAAAAAAGT-3', 7pieT, 5'-GTGTTTTTTTTGCTTTTTTTGT-3') did not activate GFP gene expression. We conclude that an imperfect palindrome affects and can increase GFP gene expression.

  14. Deep sequencing analysis reveals a TMV mutant with a poly(A) tract reduces host defense responses in Nicotiana benthamiana.

    Science.gov (United States)

    Guo, Song; Wong, Sek-Man

    2017-07-15

    Tobacco mosaic virus (TMV) possesses an upstream pseudoknotted domain (UPD), which is important for replication. After substituting the UPD with an internal poly(A) tract (43 nt), a mutant TMV-43A was constructed. TMV-43A replicated slower than TMV and induced a non-lethal mosaic symptom in Nicotiana benthamiana. In this study, deep sequencing was performed to detect the differences of small RNA profiles between TMV- and TMV-43A-infected N. benthamiana. The results showed that TMV-43A produced lesser amount of virus-derived interfering RNAs (vsiRNAs) than that of TMV. However, the distributions of vsiRNAs generation hotspots between TMV and TMV-43A were similar. Expression of genes related to small RNA biogenesis in TMV-43A-infected N. benthamiana was significantly lower than that of TMV, which leads to generation of lesser vsiRNAs. The expressions of host defense response genes were up-regulated after TMV infection, as compared to TMV-43A-infected plants. Host defense response to TMV-43A infection was lower than that to TMV. The absence of UPD might contribute to the reduced host response to TMV-43A. Our study provides valuable information in the role of the UPD in eliciting host response genes after TMV infection in N. benthamiana. (187 words). Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Star-PAP, a poly(A) polymerase, functions as a tumor suppressor in an orthotopic human breast cancer model.

    Science.gov (United States)

    Yu, C; Gong, Y; Zhou, H; Wang, M; Kong, L; Liu, J; An, T; Zhu, H; Li, Y

    2017-02-02

    Star-PAP is a noncanonical poly(A) polymerase and required for the expression of a select set of mRNAs. However, the pathological role of Star-PAP in cancer largely remains unknown. In this study, we observed decreased expression of Star-PAP in breast cancer cell lines and tissues. Ectopic Star-PAP expression inhibited proliferation as well as colony-forming ability of breast cancer cells. In breast cancer patients, high levels of Star-PAP correlated with an improved prognosis. Moreover, by regulating the expression of BIK (BCL2-interacting killer), Star-PAP induced apoptosis of breast cancer cells through the mitochondrial pathway. The growth of breast cancer xenografts in NOD/SCID mice was also inhibited by the doxycycline-induced Star-PAP overexpression. Furthermore, Star-PAP sensitized breast cancer cells to chemotherapy drugs both in vitro and in vivo. In mammary epithelial cells, Star-PAP knockdown partially transformed these cells and induced them to undergo epithelial-mesenchymal transition (EMT). These findings suggested that Star-PAP possesses tumor-suppressing activity and can be a valuable target for developing new cancer therapeutic strategies.

  16. DLM for T-Tails

    CSIR Research Space (South Africa)

    Van Zyl, Lourens H

    2007-06-01

    Full Text Available This paper describes the extension of the DLM to account for effects that are critical to the modelling of T-tail flutter. The boundary condition is made more general to account for yaw/dihedral and sideslip/dihedral coupling and the calculation...

  17. Ruin problems and tail asymptotics

    DEFF Research Database (Denmark)

    Rønn-Nielsen, Anders

    The thesis Ruin Problems and Tail Asymptotics provides results on ruin problems for several classes of Markov processes. For a class of diffusion processes with jumps an explicit expression for the joint Laplace transform of the first passage time and the corresponding undershoot is derived...

  18. Portfolio Selection with Heavy Tails

    NARCIS (Netherlands)

    N. Hyung (Namwon); C.G. de Vries (Casper)

    2004-01-01

    textabstractConsider the portfolio problem of choosing the mix between stocks and bonds under a downside risk constraint. Typically stock returns exhibit fatter tails than bonds corresponding to their greater downside risk. Downside risk criteria like the safety first criterion therefore of ten sele

  19. Little Lizard’s Tail

    Institute of Scientific and Technical Information of China (English)

    王颖敏; 乐伟国

    2008-01-01

    一、故事内容It is a lovely sunny day.Little Lizard is walking in the forest.Suddenly,a big snake stops him.Little Lizard runs as quickly as pos-sible,but his tail is bitten off(咬断)by the snake

  20. Segregation and differential settling in flocculated tailings

    Energy Technology Data Exchange (ETDEWEB)

    Farinato, R.S.; Mahmoudkhani, A.; Fenderson, T.; Watson, P. [Kemira, Atlanta, GA (United States)

    2010-07-01

    Untreated oil sands tailings have a high solids content, have poor dewaterability, and contain no aggregates. This PowerPoint presentation investigated segregation and differential settling in flocculated tailings. Tailings were treated with gypsum and various polymers. Cylinder settling, dynamic rheometry, particle size analysis, and microscopy techniques were used to characterize the composite tailings. The particles sizes of the samples were evaluated in relation to shear rate, bed depth, and treatment. The study showed that the gypsum-treated tailings had small aggregates, size stratification, a high solids content, and poor dewaterability. The polymer N-treated tailings had the lowest solids content, good dewaterability, and weak aggregates. The polymer A-treated tailings had a low solids content, very good dewaterability, and strong aggregates. The addition of a coagulant to the polymer-A treated tailings provided weaker aggregates and a higher solids content. tabs., figs.

  1. Lobster Tail Ice Formation on Aerosurface

    Science.gov (United States)

    1999-01-01

    Glace Ice formation commonly refered to as 'Lobster Tail' by scientists and engineers, is caused to form on the leading edge of a aircraft tail section in the icing research tunnel at the NASA Glenn Research Center, Cleveland, Ohio.

  2. Risk assessment of tailings facility dam failure

    OpenAIRE

    Hadzi-Nikolova, Marija; Mirakovski, Dejan; Stefanova, Violeta

    2011-01-01

    This paper presents the consequences of tailings facility dam failure and therefore the needs for its risk assessment. Tailings are fine-grained wastes of the mining industry, output as slurries, due to mixing with water during mineral processing. Tailings dams vary a lot as it is affected by: tailings characteristics and mill output, site characteristics as: topography, hydrology, geology, groundwater, seismicity and available material and disposal methods. The talings which accumulat...

  3. Active tails enhance arboreal acrobatics in geckos

    OpenAIRE

    Jusufi, Ardian; Goldman, Daniel I.; Revzen, Shai; Full, Robert J.

    2008-01-01

    Geckos are nature's elite climbers. Their remarkable climbing feats have been attributed to specialized feet with hairy toes that uncurl and peel in milliseconds. Here, we report that the secret to the gecko's arboreal acrobatics includes an active tail. We examine the tail's role during rapid climbing, aerial descent, and gliding. We show that a gecko's tail functions as an emergency fifth leg to prevent falling during rapid climbing. A response initiated by slipping causes the tail tip to p...

  4. Trail of Earth's tail

    Energy Technology Data Exchange (ETDEWEB)

    Cowley, S.W.H. (Imperial Coll. of Science and Technology, London (UK). Blackett Lab.)

    1985-05-23

    The paper concerns the observations by the ISEE-3 spacecraft of the earth's geomagnetic tail and its environs. The overall structure of the tail is described, as well as the properties of plasmas and fields both in the magnetic tail lobes and in the central current sheet that separates the lobes.

  5. Why are most EU pigs tail docked?

    DEFF Research Database (Denmark)

    D'eath, R.B.; Niemi, J.K.; Vosough Ahmadi, B.

    2016-01-01

    To limit tail biting incidence, most pig producers in Europe tail dock their piglets. This is despite EU Council Directive 2008/120/EC banning routine tail docking and allowing it only as a last resort. The paper aims to understand what it takes to fulfil the intentions of the Directive by examin...

  6. Omni-PolyA: a method and tool for accurate recognition of Poly(A) signals in human genomic DNA

    KAUST Repository

    Magana-Mora, Arturo

    2017-08-15

    BackgroundPolyadenylation is a critical stage of RNA processing during the formation of mature mRNA, and is present in most of the known eukaryote protein-coding transcripts and many long non-coding RNAs. The correct identification of poly(A) signals (PAS) not only helps to elucidate the 3′-end genomic boundaries of a transcribed DNA region and gene regulatory mechanisms but also gives insight into the multiple transcript isoforms resulting from alternative PAS. Although progress has been made in the in-silico prediction of genomic signals, the recognition of PAS in DNA genomic sequences remains a challenge.ResultsIn this study, we analyzed human genomic DNA sequences for the 12 most common PAS variants. Our analysis has identified a set of features that helps in the recognition of true PAS, which may be involved in the regulation of the polyadenylation process. The proposed features, in combination with a recognition model, resulted in a novel method and tool, Omni-PolyA. Omni-PolyA combines several machine learning techniques such as different classifiers in a tree-like decision structure and genetic algorithms for deriving a robust classification model. We performed a comparison between results obtained by state-of-the-art methods, deep neural networks, and Omni-PolyA. Results show that Omni-PolyA significantly reduced the average classification error rate by 35.37% in the prediction of the 12 considered PAS variants relative to the state-of-the-art results.ConclusionsThe results of our study demonstrate that Omni-PolyA is currently the most accurate model for the prediction of PAS in human and can serve as a useful complement to other PAS recognition methods. Omni-PolyA is publicly available as an online tool accessible at www.cbrc.kaust.edu.sa/omnipolya/.

  7. Omni-PolyA: a method and tool for accurate recognition of Poly(A) signals in human genomic DNA.

    Science.gov (United States)

    Magana-Mora, Arturo; Kalkatawi, Manal; Bajic, Vladimir B

    2017-08-15

    Polyadenylation is a critical stage of RNA processing during the formation of mature mRNA, and is present in most of the known eukaryote protein-coding transcripts and many long non-coding RNAs. The correct identification of poly(A) signals (PAS) not only helps to elucidate the 3'-end genomic boundaries of a transcribed DNA region and gene regulatory mechanisms but also gives insight into the multiple transcript isoforms resulting from alternative PAS. Although progress has been made in the in-silico prediction of genomic signals, the recognition of PAS in DNA genomic sequences remains a challenge. In this study, we analyzed human genomic DNA sequences for the 12 most common PAS variants. Our analysis has identified a set of features that helps in the recognition of true PAS, which may be involved in the regulation of the polyadenylation process. The proposed features, in combination with a recognition model, resulted in a novel method and tool, Omni-PolyA. Omni-PolyA combines several machine learning techniques such as different classifiers in a tree-like decision structure and genetic algorithms for deriving a robust classification model. We performed a comparison between results obtained by state-of-the-art methods, deep neural networks, and Omni-PolyA. Results show that Omni-PolyA significantly reduced the average classification error rate by 35.37% in the prediction of the 12 considered PAS variants relative to the state-of-the-art results. The results of our study demonstrate that Omni-PolyA is currently the most accurate model for the prediction of PAS in human and can serve as a useful complement to other PAS recognition methods. Omni-PolyA is publicly available as an online tool accessible at www.cbrc.kaust.edu.sa/omnipolya/ .

  8. Mass spectrometric identification of proteins that interact through specific domains of the poly(A) binding protein.

    Science.gov (United States)

    Richardson, Roy; Denis, Clyde L; Zhang, Chongxu; Nielsen, Maria E O; Chiang, Yueh-Chin; Kierkegaard, Morten; Wang, Xin; Lee, Darren J; Andersen, Jens S; Yao, Gang

    2012-09-01

    Poly(A) binding protein (PAB1) is involved in a number of RNA metabolic functions in eukaryotic cells and correspondingly is suggested to associate with a number of proteins. We have used mass spectrometric analysis to identify 55 non-ribosomal proteins that specifically interact with PAB1 from Saccharomyces cerevisiae. Because many of these factors may associate only indirectly with PAB1 by being components of the PAB1-mRNP structure, we additionally conducted mass spectrometric analyses on seven metabolically defined PAB1 deletion derivatives to delimit the interactions between these proteins and PAB1. These latter analyses identified 13 proteins whose associations with PAB1 were reduced by deleting one or another of PAB1's defined domains. Included in this list of 13 proteins were the translation initiation factors eIF4G1 and eIF4G2, translation termination factor eRF3, and PBP2, all of whose previously known direct interactions with specific PAB1 domains were either confirmed, delimited, or extended. The remaining nine proteins that interacted through a specific PAB1 domain were CBF5, SLF1, UPF1, CBC1, SSD1, NOP77, yGR250c, NAB6, and GBP2. In further study, UPF1, involved in nonsense-mediated decay, was confirmed to interact with PAB1 through the RRM1 domain. We additionally established that while the RRM1 domain of PAB1 was required for UPF1-induced acceleration of deadenylation during nonsense-mediated decay, it was not required for the more critical step of acceleration of mRNA decapping. These results begin to identify the proteins most likely to interact with PAB1 and the domains of PAB1 through which these contacts are made.

  9. Phylogenetic study on structural elements of HIV-1 poly(A region. 2. USE domain and TAR hairpin

    Directory of Open Access Journals (Sweden)

    Zarudnaya M. I.

    2014-01-01

    Full Text Available Aim Phylogenetic study on structural elements in the poly(A region of human immunodeficiency virus type 1 (HIV-1, in particular the major upstream sequence element (USE, which stimulates polyadenylation of HIV-1 transcript, and the TAR (trans-activation response hairpin, which juxtaposes spatially the AAUAAA and USE signals. Methods. The secondary structure of these elements has been predicted by UNA Fold program. Results. The structure of USE domain and TAR hairpin has been analysed in 1679 HIV-1 genomes and 17 genomes of simian immunodeficiency virus SIVcpzPtt. We found 376 and 588 different sequences for these elements, respectively, and revealed the most frequent base changes and subtypeand country-specific mutations. Only 43 % of HIV-1 isolates contain variants of the USE domain which occur with a frequency 5 % (the main variants and 35 % of isolates contain main variants of the TAR hairpin. We found that the SIV USE domain and TAR hairpin most closely resemble those found in HIV-1 genomes of A/G-containing subtypes. Conclusions. The results of our large-scale phylogenetic study support a hypothesis on the interaction between tRNA3Lys and the 3' end of HIV-1 genomic RNA and a controversial supposition of HIV-1 genome dimerization by the TAR-TAR kissing mechanism. Since the TAR hairpin is a target for developing antiviral drugs based on the inhibition of signal elements, the data on specific structural features of this hairpin may be useful for new antivirals design.

  10. Extracting aluminum from dross tailings

    Science.gov (United States)

    Amer, A. M.

    2002-11-01

    Aluminum dross tailings, an industrial waste, from the Egyptian Aluminium Company (Egyptalum) was used to produce two types of alums: aluminum-sulfate alum [itAl2(SO4)3.12H2O] and ammonium-aluminum alum [ (NH 4)2SO4AL2(SO4)3.24H2O]. This was carried out in two processes. The first process is leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of solute sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purifi ed aluminum dross tailings thus produced. The effects of temperature, time of reaction, and acid concentration on leaching and extraction processes were studied. The product alums were analyzed using x-ray diffraction and thermal analysis techniques.

  11. Numerical modelling for stability of tailings dams

    OpenAIRE

    Auchar, Muhammad; Mattsson, Hans; Knutsson, Sven

    2013-01-01

    A tailings dam is a large embankment structure that is constructed to store the waste from the mining industry. Stability problems may occur in a tailings dam due to factors such as quick rate of raising, internal erosion and liquefaction. The failure of a tailings dam may cause loss of human life and environmental degradation. Tailings Dams must not only be stable during the time the tailings storage facility is in operation, but also long time after the mine is closed. In Sweden, the licens...

  12. Electrodialytic remediation of suspended mine tailings

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Rojo, Adrian; Pino, Denisse;

    2008-01-01

    This work shows the laboratory results of nine electrodialytic remediation experiments on copper mine tailings. A newly designed remediation cell, where the solids were kept in suspension by airflow, was tested. The results show that electric current could remove copper from suspended tailings...... experiment at 40 mA, with approximately 137.5 g mine tailings on dry basis. The removal for a static (baseline) experiment only amounted 15% when passing approximately the same amount of charge through 130 g of mine tailings. The use of air bubbling to keep the tailings suspended increased the removal...

  13. Dural tail sign in spinal meningiomas

    Energy Technology Data Exchange (ETDEWEB)

    Alorainy, Ibrahim A. [Department of Radiology and Diagnostic Imaging, College of Medicine and King Khalid Univerity Hospital, King Saud University, P.O. Box 9047, Riyadh 11413 (Saudi Arabia)]. E-mail: alorainy@ksu.edu.sa

    2006-12-15

    Objective: To study the association between the 'dural tail sign' and spinal meningiomas on MR imaging. Methods: Retrospective review of MR examinations of all pathologically proven spinal meningiomas from 1998 to 2005 was performed. Lesions were evaluated for size, signal intensity, enhancement pattern, and presence or absence of dural tail. The dural tail length and direction in reference to the meningioma were also evaluated. Results: Seven spinal meningiomas were identified in seven patients. One lesion was purely extradural, while the remaining were intradural extramedullary. Dural tail was present in four cases (57%) and its length ranged between 5 and 21 mm. The tail was seen cranial and caudal to the meningioma in three cases and only cranially in one. Coronal images were available in three cases and in two of these; the dural tail was clearly depicted. Conclusions: 'Dural tail sign' is as common in spinal meningiomas as in cranial meningiomas.

  14. Scanning electron microscopy of Dalkon Shield tails.

    Science.gov (United States)

    Bank, H L; Williamson, H O

    1983-09-01

    Scanning electron micrographs of Dalkon Shield tails removed from asymptomatic patients show a variety of microbes and debris throughout their entire length. Apparently, even in undamaged tails, bacterial flora thrive in the protein-rich environment within the multifilament tail. The presence of microbes in the portion of the tail beyond the double knot indicates that an alternative mechanism of microbial transport can occur. Since transient endometritis often occurs immediately after insertion of intrauterine devices, microbes may come in contact with both exposed ends of the multifilament tail and be drawn into the tail by capillary action from the uterine environment down the tail toward the double knot as well as upward from the vagina. Such microorganisms could serve as an inoculum for infection.

  15. Impact of library preparation on downstream analysis and interpretation of RNA-Seq data: comparison between Illumina PolyA and NuGEN Ovation protocol.

    Directory of Open Access Journals (Sweden)

    Zhifu Sun

    Full Text Available OBJECTIVES: The sequencing by the PolyA selection is the most common approach for library preparation. With limited amount or degraded RNA, alternative protocols such as the NuGEN have been developed. However, it is not yet clear how the different library preparations affect the downstream analyses of the broad applications of RNA sequencing. METHODS AND MATERIALS: Eight human mammary epithelial cell (HMEC lines with high quality RNA were sequenced by Illumina's mRNA-Seq PolyA selection and NuGEN ENCORE library preparation. The following analyses and comparisons were conducted: 1 the numbers of genes captured by each protocol; 2 the impact of protocols on differentially expressed gene detection between biological replicates; 3 expressed single nucleotide variant (SNV detection; 4 non-coding RNAs, particularly lincRNA detection; and 5 intragenic gene expression. RESULTS: Sequences from the NuGEN protocol had lower (75% alignment rate than the PolyA (over 90%. The NuGEN protocol detected fewer genes (12-20% less with a significant portion of reads mapped to non-coding regions. A large number of genes were differentially detected between the two protocols. About 17-20% of the differentially expressed genes between biological replicates were commonly detected between the two protocols. Significantly higher numbers of SNVs (5-6 times were detected in the NuGEN samples, which were largely from intragenic and intergenic regions. The NuGEN captured fewer exons (25% less and had higher base level coverage variance. While 6.3% of reads were mapped to intragenic regions in the PolyA samples, the percentages were much higher (20-25% for the NuGEN samples. The NuGEN protocol did not detect more known non-coding RNAs such as lincRNAs, but targeted small and "novel" lincRNAs. CONCLUSION: Different library preparations can have significant impacts on downstream analysis and interpretation of RNA-seq data. The NuGEN provides an alternative for limited or

  16. Impact of library preparation on downstream analysis and interpretation of RNA-Seq data: comparison between Illumina PolyA and NuGEN Ovation protocol.

    Science.gov (United States)

    Sun, Zhifu; Asmann, Yan W; Nair, Asha; Zhang, Yuji; Wang, Liguo; Kalari, Krishna R; Bhagwate, Aditya V; Baker, Tiffany R; Carr, Jennifer M; Kocher, Jean-Pierre A; Perez, Edith A; Thompson, E Aubrey

    2013-01-01

    The sequencing by the PolyA selection is the most common approach for library preparation. With limited amount or degraded RNA, alternative protocols such as the NuGEN have been developed. However, it is not yet clear how the different library preparations affect the downstream analyses of the broad applications of RNA sequencing. Eight human mammary epithelial cell (HMEC) lines with high quality RNA were sequenced by Illumina's mRNA-Seq PolyA selection and NuGEN ENCORE library preparation. The following analyses and comparisons were conducted: 1) the numbers of genes captured by each protocol; 2) the impact of protocols on differentially expressed gene detection between biological replicates; 3) expressed single nucleotide variant (SNV) detection; 4) non-coding RNAs, particularly lincRNA detection; and 5) intragenic gene expression. Sequences from the NuGEN protocol had lower (75%) alignment rate than the PolyA (over 90%). The NuGEN protocol detected fewer genes (12-20% less) with a significant portion of reads mapped to non-coding regions. A large number of genes were differentially detected between the two protocols. About 17-20% of the differentially expressed genes between biological replicates were commonly detected between the two protocols. Significantly higher numbers of SNVs (5-6 times) were detected in the NuGEN samples, which were largely from intragenic and intergenic regions. The NuGEN captured fewer exons (25% less) and had higher base level coverage variance. While 6.3% of reads were mapped to intragenic regions in the PolyA samples, the percentages were much higher (20-25%) for the NuGEN samples. The NuGEN protocol did not detect more known non-coding RNAs such as lincRNAs, but targeted small and "novel" lincRNAs. Different library preparations can have significant impacts on downstream analysis and interpretation of RNA-seq data. The NuGEN provides an alternative for limited or degraded RNA but it has limitations for some RNA-seq applications.

  17. TMV mutants with poly(A) tracts of different lengths demonstrate structural variations in 3′UTR affecting viral RNAs accumulation and symptom expression

    OpenAIRE

    Song Guo; Elzbieta Kierzek; Gang Chen; Yi-Jun Zhou; Sek-Man Wong

    2015-01-01

    The upstream pseudoknots domain (UPD) of Tobacco mosaic virus (TMV) is located at the 3′-untranslated region (UTR). It plays an important role in virus replication and translation. To determine the importance of UPD and 3′-UTR, and the effects of introduced RNA elements in TMV 3′-UTR, a series of TMV mutants with internal poly(A) tract upstream of UPD was constructed for structural analysis by selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE). TMV(24A+UPD) and TMV(42A+UPD) ...

  18. On the classification of comet plasma tails

    Science.gov (United States)

    Mozhenkov, E. R.; Vaisberg, O. L.

    2017-07-01

    The investigation of plasma tails of comets is an important part of comet research. Different classifications of plasma tails of comets are proposed. Plasma acceleration in the tails is investigated in sufficient detail. Several cometary forms are explained. Plasma tails of Mars and Venus were observed during the first studies of these planets. They are associated with the capture of ionized atoms and exosphere molecules by the solar wind magnetized plasma flow. Distinct plasma tails of Mars and Venus are caused by the mass loading of the solar wind with heavy ions. It was shown that the transverse dimension of the tails of Mars, Venus, and comets can be quite accurately determined by production rate of the obstacle to the solar wind flow. While plasma tails of Mars and Venus are investigated by in situ measurements from spacecraft, observations of comet tails from the Earth make it possible to see the entire object under study and to monitor changes in its structure. A certain similarity of cometary and planetary tails can be explained by the nonmagnetic nature of both types of bodies. Thus, it is reasonable to suppose that investigations of plasma tails of comets can supplement the information obtained by in situ methods of the study of the planets. In this paper, plasma tails of comets, presumably analogous to the plasma tails of Mars and Venus, have been identified on modern photographs of comets (more than 1500 photographs viewed). Only quasi-steady laminar tails are considered. They are divided into two types: double structures and outflows. The paper attempts to define the 3D structure of double structures and to determine certain characteristics of outflows.

  19. PolyA-tailed and fluorophore-labeled aptamer-gold nanoparticle conjugate for fluorescence turn-on bioassay using iodide-induced ligand displacement.

    Science.gov (United States)

    Li, Wei; Dong, Yifan; Wang, Xi; Li, Hui; Xu, Danke

    2015-04-15

    Depending on the strong affinity of polyA sequence to gold (or silver) surface, applicability of polyA-tailed DNA-gold (or silver) nanoparticle conjugates in homogeneous and heterogeneous protein assays was first demonstrated. Interestingly, when using polyA-tailed, fluophore-labeled DNA-AuNP conjugate, it was found that iodide and thiosulfate anions could act as the ligand displacing reagent to detach polyA-tailed DNA strands from AuNP surface and simultaneously activate the AuNP-quenched fluorophores by destroying the polyA-AuNP interaction via a divide-and-conquer strategy. Based on this new discovery, we have developed a novel, cost-effective and sandwich-type fluorescence turn-on aptasensor for highly sensitive and specific thrombin detection, what took advantage of aptamer-conjugated magnetic beads (apt-MBs) for protein capture and separation, and iodide-induced fluorescence recovery of activatable polyA-based AuNP probes through ligand displacement for fluorescence turn-on detection. This proposed aptasensor could detect thrombin specifically with a detection limit as low as 89pM, which was better than or comparable to many existing fluorescent thrombin assays. Importantly, employment of such polyA-based AuNP conjugate not only avoids the use of thiolated oligonucleotides and thiol-containing displacing reagents, but also offers new possibilities for fabricating convenient and cost-effective bioanalytical applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Effects of tail docking and docking length on neuroanatomical changes in healed tail tips of pigs

    DEFF Research Database (Denmark)

    Herskin, M S; Thodberg, K; Jensen, Henrik Elvang

    2015-01-01

    In pig production, piglets are tail docked at birth in order to prevent tail biting later in life. In order to examine the effects of tail docking and docking length on the formation of neuromas, we used 65 pigs and the following four treatments: intact tails (n=18); leaving 75% (n=17); leaving 50......% (n=19); or leaving 25% (n=11) of the tail length on the pigs. The piglets were docked between day 2 and 4 after birth using a gas-heated apparatus, and were kept under conventional conditions until slaughter at 22 weeks of age, where tails were removed and examined macroscopically and histologically...

  1. Molecular Modeling Approaches for Determining Gene Function: application to a Putative Poly-A Binding Protein from Leishmania amazonensis (LaPABP

    Directory of Open Access Journals (Sweden)

    Silva-Jr FP

    2002-01-01

    Full Text Available The great expansion in the number of genome sequencing projects has revealed the importance of computational methods to speed up the characterization of unknown genes. These studies have been improved by the use of three dimensional information from the predicted proteins generated by molecular modeling techniques. In this work, we disclose the structure-function relationship of a gene product from Leishmania amazonensis by applying molecular modeling and bioinformatics techniques. The analyzed sequence encodes a 159 aminoacids polypeptide (estimated 18 kDa and was denoted LaPABP for its high homology with poly-A binding proteins from trypanosomatids. The domain structure, clustering analysis and a three dimensional model of LaPABP, basically obtained by homology modeling on the structure of the human poly-A binding protein, are described. Based on the analysis of the electrostatic potential mapped on the model's surface and conservation of intramolecular contacts responsible for folding stabilization we hypothesize that this protein may have less avidity to RNA than it's L. major counterpart but still account for a significant functional activity in the parasite. The model obtained will help in the design of mutagenesis experiments aimed to elucidate the mechanism of gene expression in trypanosomatids and serve as a starting point for its exploration as a potential source of targets for a rational chemotherapy.

  2. PAPERCLIP Identifies MicroRNA Targets and a Role of CstF64/64tau in Promoting Non-canonical poly(A Site Usage

    Directory of Open Access Journals (Sweden)

    Hun-Way Hwang

    2016-04-01

    Full Text Available Accurate and precise annotation of 3′ UTRs is critical for understanding how mRNAs are regulated by microRNAs (miRNAs and RNA-binding proteins (RBPs. Here, we describe a method, poly(A binding protein-mediated mRNA 3′ end retrieval by crosslinking immunoprecipitation (PAPERCLIP, that shows high specificity for mRNA 3′ ends and compares favorably with existing 3′ end mapping methods. PAPERCLIP uncovers a previously unrecognized role of CstF64/64tau in promoting the usage of a selected group of non-canonical poly(A sites, the majority of which contain a downstream GUKKU motif. Furthermore, in the mouse brain, PAPERCLIP discovers extended 3′ UTR sequences harboring functional miRNA binding sites and reveals developmentally regulated APA shifts, including one in Atp2b2 that is evolutionarily conserved in humans and results in the gain of a functional binding site of miR-137. PAPERCLIP provides a powerful tool to decipher post-transcriptional regulation of mRNAs through APA in vivo.

  3. RNA Polymerase III Subunit POLR3G Regulates Specific Subsets of PolyA(+) and SmallRNA Transcriptomes and Splicing in Human Pluripotent Stem Cells.

    Science.gov (United States)

    Lund, Riikka J; Rahkonen, Nelly; Malonzo, Maia; Kauko, Leni; Emani, Maheswara Reddy; Kivinen, Virpi; Närvä, Elisa; Kemppainen, Esko; Laiho, Asta; Skottman, Heli; Hovatta, Outi; Rasool, Omid; Nykter, Matti; Lähdesmäki, Harri; Lahesmaa, Riitta

    2017-05-09

    POLR3G is expressed at high levels in human pluripotent stem cells (hPSCs) and is required for maintenance of stem cell state through mechanisms not known in detail. To explore how POLR3G regulates stem cell state, we carried out deep-sequencing analysis of polyA(+) and smallRNA transcriptomes present in hPSCs and regulated in POLR3G-dependent manner. Our data reveal that POLR3G regulates a specific subset of the hPSC transcriptome, including multiple transcript types, such as protein-coding genes, long intervening non-coding RNAs, microRNAs and small nucleolar RNAs, and affects RNA splicing. The primary function of POLR3G is in the maintenance rather than repression of transcription. The majority of POLR3G polyA(+) transcriptome is regulated during differentiation, and the key pluripotency factors bind to the promoters of at least 30% of the POLR3G-regulated transcripts. Among the direct targets of POLR3G, POLG is potentially important in sustaining stem cell status in a POLR3G-dependent manner. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  4. Four Tails Problems for Dynamical Collapse Theories

    CERN Document Server

    McQueen, Kelvin J

    2015-01-01

    The primary quantum mechanical equation of motion entails that measurements typically do not have determinate outcomes, but result in superpositions of all possible outcomes. Dynamical collapse theories (e.g. GRW) supplement this equation with a stochastic Gaussian collapse function, intended to collapse the superposition of outcomes into one outcome. But the Gaussian collapses are imperfect in a way that leaves the superpositions intact. This is the tails problem. There are several ways of making this problem more precise. But many authors dismiss the problem without considering the more severe formulations. Here I distinguish four distinct tails problems. The first (bare tails problem) and second (structured tails problem) exist in the literature. I argue that while the first is a pseudo-problem, the second has not been adequately addressed. The third (multiverse tails problem) reformulates the second to account for recently discovered dynamical consequences of collapse. Finally the fourth (tails problem di...

  5. Unique Structural Features Facilitate Lizard Tail Autotomy

    DEFF Research Database (Denmark)

    Sanggaard, Kristian Wejse; Danielsen, C. C.; Wogensen, L.

    2012-01-01

    Autotomy refers to the voluntary shedding of a body part; a renowned example is tail loss among lizards as a response to attempted predation. Although many aspects of lizard tail autotomy have been studied, the detailed morphology and mechanism remains unclear. In the present study, we showed...... that tail shedding by the Tokay gecko (Gekko gecko) and the associated extracellular matrix (ECM) rupture were independent of proteolysis. Instead, lizard caudal autotomy relied on biological adhesion facilitated by surface microstructures. Results based on bio-imaging techniques demonstrated that the tail...

  6. High-order tail in Kerr spacetime

    CERN Document Server

    Casals, Marc; Ottewill, Adrian C

    2016-01-01

    We investigate the late-time tail of the retarded Green function for the dynamics of a linear field perturbation of Kerr spacetime. We develop an analytical formalism for obtaining the late-time tail up to arbitrary order for general integer spin of the field. We then apply this formalism to obtain the details of the first five orders in the late-time tail of the Green function for the case of a scalar field: to leading order we recover the known power law tail $t^{-2\\ell-3}$, and at third order we obtain a logarithmic correction, $t^{-2\\ell-5}\\ln t$, where $\\ell$ is the field multipole.

  7. Performance Comparison between Neutralization Tailings and Flotation Tailings Used for Backfill Mix and Mechanism Analysis

    Directory of Open Access Journals (Sweden)

    Bin Han

    2016-01-01

    Full Text Available A comparison test of different tailings used for underground backfill was conducted, using neutralized tailings from BIOX and flotation tailings of Jinfeng Mine. Laboratory comparison test results show that, with neutralized tailings, when the cement dosage is at 19%, backfill UCS after 7 days, 14 days, and 28 days are 105%–163%, 80%–102%, and 33%–43%, respectively, which are higher than those of flotation tailings. When the cement dosage is at 12%, backfill UCS after 7 days, 14 days, and 28 days are 58%–77%, 50%–60%, and 28%–51%, respectively, which are higher than those of flotation tailings. Slurry fluidity of neutralized tailings is lower than that of flotation tailings, while, in these two tailings, the difference of slump and diffusivity values is less than 6%, which is not a significant difference in slurry fluidity. The reason for neutralized tailings showing higher UCS is as follows: during backfill curing, neutralization tailings produce abundant crystals of CaSO4·2H2O in interlaced structure which helps in combining aggregates closely; CaSO4·2H2O hydrates with C3A C4AF contained in the cement and forms clavate cement bacillus which works as a micro reinforcing steel bar. The test proved that neutralized tailings are more optimal for backfilling.

  8. Profitable tail-end production

    Energy Technology Data Exchange (ETDEWEB)

    Pinchbeck, R.H.

    1997-12-31

    This presentation discusses the origins of the present challenge faced in making mature oil fields profitable in the North Sea. It briefly examines the origins of these challenges, which are rooted in the industrial psychology of the North Sea. It develops a methodological formula for the successful re-engineering of inefficiently-run assets, focusing in particular on the personnel management aspects. It identifies some key areas to seek sustainable cost reductions and recognises the importance of renewing the context for investment in tail-end fields. Finally, it speculates about the way in which the learnings developed in the experiences of the last few years will influence the future of the North Sea. 2 refs.

  9. Tailed Radio Sources in the CDFS Field

    Indian Academy of Sciences (India)

    S. Dehghan; M. Johnston-Hollitt; M. Mao; R. P. Norris; N. A. Miller; M. Huynh

    2011-12-01

    Using 1.4 GHz ATCA & VLA images with 5.5 GHz ATCA data, we present a sample of 12 bent-tailed galaxies over the 4 deg2 area of the Chandra Deep Field South (CDFS). We find 10 new sources, one of which is possibly the highest red-shift bent-tailed galaxy detected at ∼ 2.

  10. Integrative biology of tail autotomy in lizards.

    Science.gov (United States)

    Higham, Timothy E; Russell, Anthony P; Zani, Peter A

    2013-01-01

    Self-amputation (autotomy) of the tail is essential for the survival of many lizards. Accordingly, it has garnered the attention of scientists for more than 200 years. Several factors can influence the release of the tail, such as the size, sex, and age of the lizard; type of predator; ecology; and evolutionary history of the lineage. Once lost, the tail will writhe for seconds to minutes, and these movements likely depend on the size and physiology of the tail, habitat of the lizard, and predation pressure. Loss of the tail will, in turn, have impacts on the lizard, such as modified locomotor performance and mechanics, as well as escape behavior. However, the tail is almost always regenerated, and this involves wound healing, altered investment of resources, and tissue differentiation. The regenerated tail generally differs from the original in several ways, including size, shape, and function. Here we summarize recent findings of research pertaining to tail autotomy, and we propose a framework for future investigations.

  11. Electrodialytic remediation of copper mine tailings

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Rojo, A.; Ottpsen, Lisbeth M.

    2005-01-01

    Mining activities in Chile have generated large amounts of solid waste, which have been deposited in mine tailing impoundments. These impoundments cause concern to the communities due to dam failures or natural leaching to groundwater and rivers.This work shows the laboratory results of nine...... electrodialytic remediation experiments on copper mine tailings. The results show that electric current could remove copper from watery tailing if the potential gradient was higher than 2V/cm during 21 days. With addition of sulphuric acid, the process was enhanced because the pH decreased to around 4......, and the copper by this reason was released in the solution. Furthermore, with acidic tailing the potential gradient was less than 2V/cm.The maximum copper removal reached in the anode side was 53% with addition of sulphuric acid in 21 days experiment at 20V using approximately 1.8kg mine tailing on dry basis...

  12. Performance Comparison between Neutralization Tailings and Flotation Tailings Used for Backfill Mix and Mechanism Analysis

    OpenAIRE

    Bin Han; Wei Sun; Shaofeng Yu; Chao Liu; Song Yao; Jianxun Wu

    2016-01-01

    A comparison test of different tailings used for underground backfill was conducted, using neutralized tailings from BIOX and flotation tailings of Jinfeng Mine. Laboratory comparison test results show that, with neutralized tailings, when the cement dosage is at 19%, backfill UCS after 7 days, 14 days, and 28 days are 105%–163%, 80%–102%, and 33%–43%, respectively, which are higher than those of flotation tailings. When the cement dosage is at 12%, backfill UCS after 7 days, 14 days, and 28 ...

  13. Injurious tail biting in pigs: how can it be controlled in existing systems without tail docking?

    Science.gov (United States)

    D'Eath, R B; Arnott, G; Turner, S P; Jensen, T; Lahrmann, H P; Busch, M E; Niemi, J K; Lawrence, A B; Sandøe, P

    2014-09-01

    Tail biting is a serious animal welfare and economic problem in pig production. Tail docking, which reduces but does not eliminate tail biting, remains widespread. However, in the EU tail docking may not be used routinely, and some 'alternative' forms of pig production and certain countries do not allow tail docking at all. Against this background, using a novel approach focusing on research where tail injuries were quantified, we review the measures that can be used to control tail biting in pigs without tail docking. Using this strict criterion, there was good evidence that manipulable substrates and feeder space affect damaging tail biting. Only epidemiological evidence was available for effects of temperature and season, and the effect of stocking density was unclear. Studies suggest that group size has little effect, and the effects of nutrition, disease and breed require further investigation. The review identifies a number of knowledge gaps and promising avenues for future research into prevention and mitigation. We illustrate the diversity of hypotheses concerning how different proposed risk factors might increase tail biting through their effect on each other or on the proposed underlying processes of tail biting. A quantitative comparison of the efficacy of different methods of provision of manipulable materials, and a review of current practices in countries and assurance schemes where tail docking is banned, both suggest that daily provision of small quantities of destructible, manipulable natural materials can be of considerable benefit. Further comparative research is needed into materials, such as ropes, which are compatible with slatted floors. Also, materials which double as fuel for anaerobic digesters could be utilised. As well as optimising housing and management to reduce risk, it is important to detect and treat tail biting as soon as it occurs. Early warning signs before the first bloody tails appear, such as pigs holding their tails tucked

  14. On tail behavior of nonlinear autoregressive functional conditional heteroscedastic model with heavy-tailed innovations

    Institute of Scientific and Technical Information of China (English)

    PAN; Jiazhu; WU; Guangxu

    2005-01-01

    We study the tail probability of the stationary distribution of nonparametric nonlinear autoregressive functional conditional heteroscedastic (NARFCH) model with heavytailed innovations. Our result shows that the tail of the stationary marginal distribution of an NARFCH series is heavily dependent on its conditional variance. When the innovations are heavy-tailed, the tail of the stationary marginal distribution of the series will become heavier or thinner than that of its innovations. We give some specific formulas to show how the increment or decrement of tail heaviness depends on the assumption on the conditional variance function. Some examples are given.

  15. Shake a tail feather: the evolution of the theropod tail into a stiff aerodynamic surface.

    Directory of Open Access Journals (Sweden)

    Michael Pittman

    Full Text Available Theropod dinosaurs show striking morphological and functional tail variation; e.g., a long, robust, basal theropod tail used for counterbalance, or a short, modern avian tail used as an aerodynamic surface. We used a quantitative morphological and functional analysis to reconstruct intervertebral joint stiffness in the tail along the theropod lineage to extant birds. This provides new details of the tail's morphological transformation, and for the first time quantitatively evaluates its biomechanical consequences. We observe that both dorsoventral and lateral joint stiffness decreased along the non-avian theropod lineage (between nodes Theropoda and Paraves. Our results show how the tail structure of non-avian theropods was mechanically appropriate for holding itself up against gravity and maintaining passive balance. However, as dorsoventral and lateral joint stiffness decreased, the tail may have become more effective for dynamically maintaining balance. This supports our hypothesis of a reduction of dorsoventral and lateral joint stiffness in shorter tails. Along the avian theropod lineage (Avialae to crown group birds, dorsoventral and lateral joint stiffness increased overall, which appears to contradict our null expectation. We infer that this departure in joint stiffness is specific to the tail's aerodynamic role and the functional constraints imposed by it. Increased dorsoventral and lateral joint stiffness may have facilitated a gradually improved capacity to lift, depress, and swing the tail. The associated morphological changes should have resulted in a tail capable of producing larger muscular forces to utilise larger lift forces in flight. Improved joint mobility in neornithine birds potentially permitted an increase in the range of lift force vector orientations, which might have improved flight proficiency and manoeuvrability. The tail morphology of modern birds with tail fanning capabilities originated in early ornithuromorph

  16. Interruption of env gene expression depending on the length of the SV40 early region used for the polyA signal.

    Science.gov (United States)

    Yamakawa, Kei; Takase-Yoden, Sayaka; Watanabe, Rihito

    2005-12-01

    In order to invent a screening system to check in vivo gene function and the efficiency of gene transfer mediated by a retroviral vector system, we established a novel packaging cell, PacNIH/A8, based on the neuropathogenic retrovirus A8-V. To construct the expression vector, pA8(Psi-), which expresses the genes gag, pol and env derived from A8-V, the SV40 early region was used for the polyadenylation signal (polyA signal). When a 0.85 kbp fragment in the SV40 early region was employed for the expression vector (pA8(Psi-)beta), env expression was abolished. This abolition was rescued by shortening the SV40 early region to 0.14 kbp (pA8(Psi-)delta). The NHI3T3 cells transfected with pA8(Psi-)delta showed expressions of both env and gag genes.

  17. Basic description of tailings from Aitik focusing on mechanical behavior

    OpenAIRE

    Bhanbhro, Riaz; Knutsson, Roger; Rodriguez, Juan; Edeskär, Tommy; Knutsson, Sven

    2013-01-01

    Tailings are artificial granular materials that behave different as compared to natural soil of equal grain sizes. Tailings particle sizes, shapes, gradation and mechanical behavior may influence the performance of tailings dams. Hence it is essential to understand the tailings materials in depth. This article describes present studies being carried out on Aitik tailings. Basic tailings characteristics including specific gravity, phase relationships, particle sizes, particle shapes and direct...

  18. APPLICATION OF POSTFLOTATION TAILINGS IN HYDROENGINEERING STRUCTURES

    Directory of Open Access Journals (Sweden)

    Katarzyna Stefaniak

    2017-01-01

    Full Text Available Economic development stimulated by the increased demand for production of consumer goods and the growing human population result in increasing amounts of various wastes, including tailings. The mining industry in Poland, comprising also mining of non-ferrous metal ores, is a strategic branch of the national economy and at the same time a leading waste producer. Tailings management is a significant problem both in Poland and worldwide. Frequently considerable amounts of wastes are accumulated in mine spoil tips, in areas not always suitable for their deposition, thus leading to the degradation of the surrounding environment. At the huge volume of produced wastes their rational and economically viable management is becoming crucial. On the other hand, depletion of natural aggregate deposits is an important incentive to search for substitutes, which would be suitable for the development of road infrastructure or which could be used in earth structure engineering to construct hydroengineering objects. Since no profitable recovery technologies are available at present, tailings generated by copper mining are deposited in tailings storage facilities. The largest and at the same time the only currently operating facility in Poland is the Żelazny Most Mining Tailings Storage Facility, belonging to KGHM Polska Miedź S.A. The paper presents criteria for material quality and density imposed on the material embedded in the static core of the tailings pond dam. For this purpose studies were conducted to confirm applicability of sorted tailings as a material for the construction of earth structures.

  19. Asbestos Tailings as Aggregates for Asphalt Mixture

    Institute of Scientific and Technical Information of China (English)

    LIU Xinoming; XU Linrong

    2011-01-01

    To use many asbestos tailings collected in Ya-Lu highway, and to explore the feasibility of using asbestos tailings as aggregates in common asphalt mixtures, and properties of some asphalt mixtures were evaluated as well. X-ray diffraction (XRD), X-ray fluorescent (XRF), and atomic absorption spectrophotometry (AAS) were employed to determine the solid waste content of copper, zinc, lead, and cadmium. Volume properties and pavement performances of AC-25 asphalt mixture with asbestos tailings were also evaluated compared with those with basalt as aggregates.XRD and XRF measurement results infer that asbestos tailing is an excellent road material. Volume properties of AC-25 asphalt mixture with asbestos tailings satisfied the related specifications. No heavy metals and toxic pollution were detected in AAS test and the value of pH test is 8.23, which is help to the adhesion with asphalt in the asphalt concrete. When compared with basalt, high temperature property and the resistance to low temperature cracking of AC-25 asphalt mixture was improved by using asbestos tailings as aggregates. In-service AC-25 asphalt pavement with asbestos tailings also presented excellent performance and British Pendulum Number (BPN) coefficient of surface.

  20. The concepts of tail moment and tail inertia in the single cell gel electrophoresis assay.

    Science.gov (United States)

    Hellman, B; Vaghef, H; Boström, B

    1995-03-01

    Single cell gel electrophoresis under alkaline conditions is a technique used to detect primary DNA damage in individual mammalian cells. Cells embedded in agarose on microscope slides are subjected to lysis, unwinding of DNA and electrophoresis at high pH. After staining with a fluorescent dye, cells with DNA damage display increased migration of genetic material from the cell nucleus. The damage is quantified by measuring the displacement between the genetic material of the nucleus ('comet head') and the resulting 'tail'. The torsional moment of the tail ('tail moment') has been suggested to be an appropriate index of induced DNA damage in considering both the migration of the genetic material as well as the relative amount of DNA in the tail. In the present paper it will be shown that the moment of inertia ('tail inertia'), a not previously described tail parameter, provides a more precise description of the distribution of individual DNA fragments within the tails. The tail inertia was also found to be the most sensitive indicator of the DNA damage induced in peripheral lymphocytes from mice given a single intraperitoneal injection of cyclophosphamide (150 mg/kg b.w.). It is concluded that the tail inertia is an important complement to other tail parameters when looking for damage of DNA with the single cell gel electrophoresis assay.

  1. Unconventional tail configurations for transport aircraft

    Science.gov (United States)

    Sánchez-Carmona, A.; Cuerno-Rejado, C.; García-Hernández, L.

    2017-06-01

    This article presents the bases of a methodology in order to size unconventional tail configurations for transport aircraft. The case study of this paper is a V-tail con¦guration. Firstly, an aerodynamic study is developed for determining stability derivatives and aerodynamic forces. The objective is to size a tail such as it develops at least the same static stability derivatives than a conventional reference aircraft. The optimum is obtained minimizing its weight. The weight is estimated through two methods: adapted Farrar£s method and a statistical method. The solution reached is heavier than the reference, but it reduces the wetted area.

  2. Topological defects with power-law tails

    CERN Document Server

    Radomskiy, Roman V; Gani, Vakhid A; Christov, Ivan C

    2016-01-01

    We study interactions of kinks and antikinks of the $(1+1)$-dimensional $\\varphi^8$ model. In this model, there are kinks with mixed tail asymptotics: power-law behavior at one infinity versus exponential decay towards the other. We show that if a kink and an antikink face each other in way such that their power-law tails determine the kink--antikink interaction, then the force of their interaction decays slowly, as some negative power of distance between them. We estimate the force numerically using the collective coordinate approximation, and analytically via Manton's method (making use of formulas derived for the kink and antikink tail asymptotics).

  3. SPS Scraping and LHC Transverse Tails

    CERN Document Server

    Drøsdal, L; Goddard, B; Kain, V; Meddahi, M; Mete, O; Salvachua, B; Valentino, G; Veyrunes, E

    2013-01-01

    All high-intensity LHC beams have to be scraped before extraction from the SPS to remove the non-Gaussian transverse tails of the particle distributions. The tail particles would otherwise cause unacceptably high losses during injection or other phases of the LHC cycle. Studies have been carried out to quantify the scraping using injection losses and emittance measurements from wire scanners as diagnostics. Beams scraped in the SPS were scraped again in the LHC with collimators to investigate possible tail repopulation. The results of these studies will be presented in this paper.

  4. Hovercraft drill probes Saraji tailings dam

    Energy Technology Data Exchange (ETDEWEB)

    1991-09-01

    In early operations at BHP-Utah's Saraji Mine in central Queensland, quantities of coking coal were pumped into the tailings dam because the preparation plant's flotation circuit was unable to handle ultra-fines. A reverse circulating drilling rig mounted on a hovercraft was used to recover 22 samples (representing 9 metres of tailings from 11 x 8 x 0.09 metre cores) in an investigation into whether the tailings can now be treated economically. 1 fig.

  5. Variation in salamander tail regeneration is associated with genetic factors that determine tail morphology.

    Directory of Open Access Journals (Sweden)

    Gareth J Voss

    Full Text Available Very little is known about the factors that cause variation in regenerative potential within and between species. Here, we used a genetic approach to identify heritable genetic factors that explain variation in tail regenerative outgrowth. A hybrid ambystomatid salamander (Ambystoma mexicanum x A. andersoni was crossed to an A. mexicanum and 217 offspring were induced to undergo metamorphosis and attain terrestrial adult morphology using thyroid hormone. Following metamorphosis, each salamander's tail tip was amputated and allowed to regenerate, and then amputated a second time and allowed to regenerate. Also, DNA was isolated from all individuals and genotypes were determined for 187 molecular markers distributed throughout the genome. The area of tissue that regenerated after the first and second amputations was highly positively correlated across males and females. Males presented wider tails and regenerated more tail tissue during both episodes of regeneration. Approximately 66-68% of the variation in regenerative outgrowth was explained by tail width, while tail length and genetic sex did not explain a significant amount of variation. A small effect QTL was identified as having a sex-independent effect on tail regeneration, but this QTL was only identified for the first episode of regeneration. Several molecular markers significantly affected regenerative outgrowth during both episodes of regeneration, but the effect sizes were small (<4% and correlated with tail width. The results show that ambysex and minor effect QTL explain variation in adult tail morphology and importantly, tail width. In turn, tail width at the amputation plane largely determines the rate of regenerative outgrowth. Because amputations in this study were made at approximately the same position of the tail, our results resolve an outstanding question in regenerative biology: regenerative outgrowth positively co-varies as a function of tail width at the amputation site.

  6. Variation in salamander tail regeneration is associated with genetic factors that determine tail morphology.

    Science.gov (United States)

    Voss, Gareth J; Kump, D Kevin; Walker, John A; Voss, S Randal

    2013-01-01

    Very little is known about the factors that cause variation in regenerative potential within and between species. Here, we used a genetic approach to identify heritable genetic factors that explain variation in tail regenerative outgrowth. A hybrid ambystomatid salamander (Ambystoma mexicanum x A. andersoni) was crossed to an A. mexicanum and 217 offspring were induced to undergo metamorphosis and attain terrestrial adult morphology using thyroid hormone. Following metamorphosis, each salamander's tail tip was amputated and allowed to regenerate, and then amputated a second time and allowed to regenerate. Also, DNA was isolated from all individuals and genotypes were determined for 187 molecular markers distributed throughout the genome. The area of tissue that regenerated after the first and second amputations was highly positively correlated across males and females. Males presented wider tails and regenerated more tail tissue during both episodes of regeneration. Approximately 66-68% of the variation in regenerative outgrowth was explained by tail width, while tail length and genetic sex did not explain a significant amount of variation. A small effect QTL was identified as having a sex-independent effect on tail regeneration, but this QTL was only identified for the first episode of regeneration. Several molecular markers significantly affected regenerative outgrowth during both episodes of regeneration, but the effect sizes were small (<4%) and correlated with tail width. The results show that ambysex and minor effect QTL explain variation in adult tail morphology and importantly, tail width. In turn, tail width at the amputation plane largely determines the rate of regenerative outgrowth. Because amputations in this study were made at approximately the same position of the tail, our results resolve an outstanding question in regenerative biology: regenerative outgrowth positively co-varies as a function of tail width at the amputation site.

  7. Impact of copy number of distinct SV40PolyA segments on expression of a GFP reporter gene

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The presence of Alu repeats downregulates the expression of the green fluorescent protein(GFP) gene.We found that SV40PolyA(PolyA,240 bp),in either orientation,eliminated the inhibition of GFP gene expression induced by Alu repeats when it was placed between the GFP gene and the Alu repeats.In this study,4 different segments(each 60 bp) were amplified from antisense PolyA(PolyAas) by PCR,and inserted upstream of Alu14 in pAlu14 plasmid(14 Alu repeats inserted downstream of the GFP gene in vector pEGFP-C1 in a head-tail tandem manner).Segments 1F1R(the first 60 bp segment at the 5’ end of PolyAas) and 4F4R(the fourth 60 bp segment from the 5’ end of PolyAas) did not activate GFP gene expression,whereas 2F2R and 3F3R(the middle two segments) did(as detected by Northern blot analysis and fluorescent microscopy).Different copy numbers of 2F2R and 3F3R segments,in a head and tail tandem manner,were inserted downstream of the GFP gene in pAlu14.p2F2R*4-Alu28,p3F3R*4-Alu18 and p3F3R*4-Alu28 were used as length controls to verify that the decrease in the expression of GFP was not due to the increased length of the inserted segment in the expression vectors.We found that 2 and 4 copies of 2F2R or 3F3R activated the GFP gene more strongly than one copy of them.However,more than 8 copies of 2F2R or 3F3R reduced the activation of the GFP gene.We concluded that SV40PolyAas contained at least two gene-activating elements(2F2R and 3F3R) and 2-4 copies of 2F2R or 3F3R were optimal for the expression of the GFP gene.

  8. Underground void filling by cemented mill tailings

    Institute of Scientific and Technical Information of China (English)

    Choudhary Bhanwar Singh; Kumar Santosh

    2013-01-01

    Underground mining always create voids. These voids can cause subsidence of surface. So it is always a demand to fill the void in such a manner that the effect of underground mining can be minimized. Void filling using mill tailings especially in metal mining is one of the best techniques. The tailings produced in milling process have traditionally been disposed in tailing ponds creating a waste disposal and environ-mental problems in terms of land degradation, air and water pollution, etc. This disposal practice is more acute in the metal milling industry where the fine grinding, required for value liberation, results in the production of very fine tailings in large percentage. This paper includes discussions on the effectiveness of different paste mixes with varying cement contents in paste backfilling operations. The results revealed that material composition and use of super plasticizer strongly influenced the strength of cemented backfill.

  9. Physical space and long-tail markets

    Science.gov (United States)

    Bentley, R. Alexander; Madsen, Mark E.; Ormerod, Paul

    2009-03-01

    The Internet is known to have had a powerful impact on on-line retailer strategies in markets characterised by long-tail distribution of sales [C. Anderson, Long Tail: Why the Future of Business is Selling Less of More, Hyperion, New York, 2006]. Such retailers can exploit the long tail of the market, since they are effectively without physical limit on the number of choices on offer. Here we examine two extensions of this phenomenon. First, we introduce turnover into the long-tail distribution of sales. Although over any given period such as a week or a month, the distribution is right-skewed and often power law distributed, over time there is considerable turnover in the rankings of sales of individual products. Second, we establish some initial results on the implications for shelf-space and physical retailers in such markets.

  10. Electrodialytic Remediation of Copper Mine Tailings

    DEFF Research Database (Denmark)

    Hansen, H.K.; Rojo, A.; Ottosen, L.M.

    2012-01-01

    This work compares and evaluates sixteen electrodialytic laboratory remediation experiments on copper mine tailings. Different parameters were analysed, such as remediation time, addition of desorbing agents, and the use of pulsed electrical fields.......This work compares and evaluates sixteen electrodialytic laboratory remediation experiments on copper mine tailings. Different parameters were analysed, such as remediation time, addition of desorbing agents, and the use of pulsed electrical fields....

  11. On high energy tails in inelastic gases

    OpenAIRE

    Lambiotte, R.; Brenig, L.; Salazar, J. M.

    2005-01-01

    We study the formation of high energy tails in a one-dimensional kinetic model for granular gases, the so-called Inelastic Maxwell Model. We introduce a time- discretized version of the stochastic process, and show that continuous time implies larger fluctuations of the particles energies. This is due to a statistical relation between the number of inelastic collisions undergone by a particle and its average energy. This feature is responsible for the high energy tails in the model, as shown ...

  12. Poisson vs. Long-Tailed Internet traffic

    OpenAIRE

    2005-01-01

    In this thesis, we reexamine the long discussion on which model is suitable for studying Internet traffic: Poisson or Long-tailed Internet traffic. Poisson model, adapted from telephone network, has been used since the beginning of World Wide Web, while long-tailed distribution gradually takes over with believable evidence. Instead of using Superposition of Point Processes to explain why traffic that is not Poisson tends towards Poisson traffic as the load increases, as it is recent...

  13. Mechanical Properties of Soft Tailings from a Swedish Tailings Impoundment:Results from Direct Shear Tests

    OpenAIRE

    Bhanbhro, Riaz; Knutsson, Roger; Edeskär, Tommy; Knutsson, Sven

    2014-01-01

    The shear strength of tailings can vary depending upon the type of ore and method of construction. Tailings dams may possess loose layers in subsequent layers, which may have low shear strength. Since the tailings dams are made-up to last for longer times, the strength parameters and material behaviors are essential to understand, especially potential for static liquefaction in loose layers. This article presents the results from direct shear tests performed on samples from loose layer of a t...

  14. Hybrid Tail Risk and Expected Stock Returns: When Does the Tail Wag the Dog?

    OpenAIRE

    Bali, Turan G.; Nusret Cakici; Robert F. Whitelaw

    2013-01-01

    We introduce a new, hybrid measure of stock return tail covariance risk, motivated by the under-diversified portfolio holdings of individual investors, and investigate its cross-sectional predictive power. Our key innovation is that this covariance is measured across the left tail states of the individual stock return distribution, not across those of the market return as in standard systematic risk measures. We document a positive and significant relation between hybrid tail covariance risk ...

  15. Electrodialytic remediation of copper mine tailings.

    Science.gov (United States)

    Hansen, Henrik K; Rojo, Adrián; Ottosen, Lisbeth M

    2005-01-31

    Mining activities in Chile have generated large amounts of solid waste, which have been deposited in mine tailing impoundments. These impoundments cause concern to the communities due to dam failures or natural leaching to groundwater and rivers. This work shows the laboratory results of nine electrodialytic remediation experiments on copper mine tailings. The results show that electric current could remove copper from watery tailing if the potential gradient was higher than 2 V/cm during 21 days. With addition of sulphuric acid, the process was enhanced because the pH decreased to around 4, and the copper by this reason was released in the solution. Furthermore, with acidic tailing the potential gradient was less than 2 V/cm. The maximum copper removal reached in the anode side was 53% with addition of sulphuric acid in 21 days experiment at 20 V using approximately 1.8 kg mine tailing on dry basis. In addition, experiments with acidic tailing show that the copper removal is proportional with time.

  16. Four tails problems for dynamical collapse theories

    Science.gov (United States)

    McQueen, Kelvin J.

    2015-02-01

    The primary quantum mechanical equation of motion entails that measurements typically do not have determinate outcomes, but result in superpositions of all possible outcomes. Dynamical collapse theories (e.g. GRW) supplement this equation with a stochastic Gaussian collapse function, intended to collapse the superposition of outcomes into one outcome. But the Gaussian collapses are imperfect in a way that leaves the superpositions intact. This is the tails problem. There are several ways of making this problem more precise. But many authors dismiss the problem without considering the more severe formulations. Here I distinguish four distinct tails problems. The first (bare tails problem) and second (structured tails problem) exist in the literature. I argue that while the first is a pseudo-problem, the second has not been adequately addressed. The third (multiverse tails problem) reformulates the second to account for recently discovered dynamical consequences of collapse. Finally the fourth (tails problem dilemma) shows that solving the third by replacing the Gaussian with a non-Gaussian collapse function introduces new conflict with relativity theory.

  17. The Sodium Tail of the Moon

    Science.gov (United States)

    Matta, M.; Smith, S.; Baumgardner, J.; Wilson, J.; Martinis, C.; Mendillo, M.

    2009-01-01

    During the few days centered about new Moon, the lunar surface is optically hidden from Earth-based observers. However, the Moon still offers an observable: an extended sodium tail. The lunar sodium tail is the escaping "hot" component of a coma-like exosphere of sodium generated by photon-stimulated desorption, solar wind sputtering and meteoroid impact. Neutral sodium atoms escaping lunar gravity experience solar radiation pressure that drives them into the anti-solar direction forming a comet-like tail. During new Moon time, the geometry of the Sun, Moon and Earth is such that the anti-sunward sodium flux is perturbed by the terrestrial gravitational field resulting in its focusing into a dense core that extends beyond the Earth. An all-sky camera situated at the El Leoncito Observatory (CASLEO) in Argentina has been successfully imaging this tail through a sodium filter at each lunation since April 2006. This paper reports on the results of the brightness of the lunar sodium tail spanning 31 lunations between April 2006 and September 2008. Brightness variability trends are compared with both sporadic and shower meteor activity, solar wind proton energy flux and solar near ultra violet (NUV) patterns for possible correlations. Results suggest minimal variability in the brightness of the observed lunar sodium tail, generally uncorrelated with any single source, yet consistent with a multi-year period of minimal solar activity and non-intense meteoric fluxes.

  18. Tail dependence of random variables from ARCH and heavy tailed bilinear models

    Institute of Scientific and Technical Information of China (English)

    潘家柱

    2002-01-01

    Discussed in this paper is the dependent structure in the tails of distributions of random variables from some heavy-tailed stationary nonlinear time series. One class of models discussed is the first-order autoregressive conditional heteroscedastic (ARCH) process introduced by Engle (1982). The other class is the simple first-order bilinear models driven by heavy-tailed innovations. We give some explicit formulas for the asymptotic values of conditional probabilities used for measuring the tail dependence between two random variables from these models. Our results have significant meanings in finance.

  19. Nonlinear autoregressive models with heavy-tailed innovation

    Institute of Scientific and Technical Information of China (English)

    JIN; Yang; AN; Hongzhi

    2005-01-01

    In this paper, we discuss the relationship between the stationary marginal tail probability and the innovation's tail probability of nonlJnear autoregressive models. We show that under certain conditions that ensure the stationarity and ergodicity, one dimension stationary marginal distribution has the heavy-tailed probability property with the same index as that of the innovation's tail probability.

  20. Attitudes of Dutch Pig Farmers Towards Tail Biting and Tail Docking

    NARCIS (Netherlands)

    Bracke, M.B.M.; Lauwere, de C.C.; Wind, S.M.M.; Zonderland, J.J.

    2013-01-01

    The Dutch policy objective of a fully sustainable livestock sector without mutilations by 2023 is not compatible with the routine practice of tail docking to minimize the risk of tail biting. To examine farmer attitudes towards docking, a telephone survey was conducted among 487 conventional and 33

  1. Attitudes of Dutch Pig Farmers Towards Tail Biting and Tail Docking

    NARCIS (Netherlands)

    Bracke, M.B.M.; Lauwere, de C.C.; Wind, S.M.M.; Zonderland, J.J.

    2013-01-01

    The Dutch policy objective of a fully sustainable livestock sector without mutilations by 2023 is not compatible with the routine practice of tail docking to minimize the risk of tail biting. To examine farmer attitudes towards docking, a telephone survey was conducted among 487 conventional and 33

  2. Tail Asymptotics for the Sum of two Heavy-tailed Dependent Risks

    DEFF Research Database (Denmark)

    Albrecher, H.; Asmussen, Søren

    Let X1,X2 denote positive exchangable heavy-tailed random variables with continuous marginal distribution function F. The asymptotic behavior of the tail of X1 + X2 is studied in a general copula framework and some bounds and extremal properties are provided. For more specific assumptions on F...

  3. The tidal tails of NGC 2298

    CERN Document Server

    Balbinot, Eduardo; da Costa, Luiz N; Makler, Martin; Maia, Marcio A G

    2011-01-01

    We present an implementation of the matched-filter technique to detect tidal tails of globular clusters. The method was tested using SDSS data for the globular cluster Palomar 5 revealing its well known tidal tails. We also ran a simulation of a globular cluster with a tidal tail where we successfully recover the tails for a cluster at the same position and with the same characteristics of NGC 2298. Based on the simulation we estimate that the matched-filter increases the contrast of the tail relative to the background of stars by a factor of 2.5 for the case of NGC 2298. We also present the photometry of the globular cluster NGC 2298 using the MOSAIC2 camera installed on the CTIO 4m telescope. The photometry covers ~ 3deg2 reaching V ~ 23. A fit of a King profile to the radial density profile of NGC 2298 shows that this cluster has a tidal radius of 15.91' \\pm 1.07' which is twice as in the literature. The application of the matched-filter to NGC 2298 reveals several extra-tidal structures, including a leadi...

  4. How does innovation's tail risk determine marginal tail risk of a stationary financial time series?

    Institute of Scientific and Technical Information of China (English)

    PAN; Jiazhu; YU; Bosco; W.T.; PANG; W.K.

    2004-01-01

    We discuss the relationship between the marginal tail risk probability and the innovation'stail risk probability for some stationary financial time series models.We first give the main results on the tail behavior of a class of infinite weighted sums of random variableswith heavy-tailed probabilities. And then, the main results are applied tothree important types of time series models:infinite order moving averages, the simple bilinear time series and the solutions of stochasticdifference equations. The explicit formulas are given to describe how the marginaltail probabilities come from the innovation's tail probabilities for these time series.Our results can be applied to the tail estimation of time series and are useful for risk analysis in finance.

  5. Design of tailing dam using red mud

    Science.gov (United States)

    Rout, Subrat; Sahoo, Tapaswini; Das, Sarat

    2013-06-01

    Red mud, waste industrial product from aluminum industries produced approximately 75 million tonnes every year with less than half of this is used. Storage of this unutilized red mud takes vast tracts of usable land and pollutes, land, air and water. Construction of high embankments, under passes, flyovers, tailing dams uses vast tract of natural resources (top soil) is also matter of concern as its takes thousands of years to form the natural soil. This paper discusses use of red mud for construction of tailing dam based on laboratory findings and finite element analysis. The geotechnical properties such as plasticity, compaction, permeability, shear strength characteristics and dispersion of red mud are presented. Stability and seepage analysis of tailing dams as per finite element analysis using the above geotechnical parameters is presented.

  6. International experience in tailings pond remediation

    Energy Technology Data Exchange (ETDEWEB)

    MacG. Robertson, A. [Robertson GeoConsultants Ltd., Vancouver (Canada)

    2001-07-01

    Tailings pond remediation is required primarily on mine closure. While mining is an ancient industry, requirement for mine facility remediation is a comparatively new development. Requirement for remediation has come about partly as a result of mans awareness of the environmental impacts of mining and his desire to minimize this, partly, as a result of the ever-increasing scale and production rates of tailings generation and the resulting increased environmental impacts and safety risks. The paper starts with a review of the evolution of mans intolerance of environmental impacts from tailings production and the assignment of liability to remediate such impacts. Many of the tailings ponds currently undergoing remediation were designed and constructed using methods and technology that would be considered inappropriate for new impoundments being designed and developed today. The paper reviews the history of tailings impoundment design and construction practice and the resulting inherent deficiencies that must be remediated. Current practices and future trends in tailings pond remediation are reviewed. The evolution of regulatory requirements is not only in terms of technical and safety criteria, but also in terms of financial and political risk. Perhaps the most substantive driver of risk management is today the requirement for corporate governance at mining company board level and oversight of new project development in the underdeveloped countries by the large financial institutions responsible for funding projects. Embarrassment in the public eye and punishment in the stock markets for poor environmental and safety performance is driving the need for efficient and effective risk management of potential impacts and the remediation to avoid these. A basis for practical risk management is described. (orig.)

  7. Stimulation of translation by human Unr requires cold shock domains 2 and 4, and correlates with poly(A) binding protein interaction.

    Science.gov (United States)

    Ray, Swagat; Anderson, Emma C

    2016-03-03

    The RNA binding protein Unr, which contains five cold shock domains, has several specific roles in post-transcriptional control of gene expression. It can act as an activator or inhibitor of translation initiation, promote mRNA turnover, or stabilise mRNA. Its role depends on the mRNA and other proteins to which it binds, which includes cytoplasmic poly(A) binding protein 1 (PABP1). Since PABP1 binds to all polyadenylated mRNAs, and is involved in translation initiation by interaction with eukaryotic translation initiation factor 4G (eIF4G), we investigated whether Unr has a general role in translational control. We found that Unr strongly stimulates translation in vitro, and mutation of cold shock domains 2 or 4 inhibited its translation activity. The ability of Unr and its mutants to stimulate translation correlated with its ability to bind RNA, and to interact with PABP1. We found that Unr stimulated the binding of PABP1 to mRNA, and that Unr was required for the stable interaction of PABP1 and eIF4G in cells. siRNA-mediated knockdown of Unr reduced the overall level of cellular translation in cells, as well as that of cap-dependent and IRES-dependent reporters. These data describe a novel role for Unr in regulating cellular gene expression.

  8. Fission yeast Mog1p homologue, which interacts with the small GTPase Ran, is required for mitosis-to-interphase transition and poly(A)(+) RNA metabolism.

    Science.gov (United States)

    Tatebayashi, K; Tani, T; Ikeda, H

    2001-04-01

    We have cloned and characterized the Schizosaccharomyces pombe gene mog1(+), which encodes a protein with homology to the Saccharomyces cerevisiae Mog1p participating in the Ran-GTPase system. The S. pombe Mog1p is predominantly localized in the nucleus. In contrast to the S. cerevisiae MOG1 gene, the S. pombe mog1(+) gene is essential for cell viability. mog1(+) is required for the mitosis-to-interphase transition, as the mog1-1 mutant arrests at restrictive temperatures as septated, binucleated cells with highly condensed chromosomes and an aberrant nuclear envelope. FACS analysis showed that these cells do not undergo a subsequent round of DNA replication. Surprisingly, also unlike the Delta mog1 mutation in S. cerevisiae, the mog1-1 mutation causes nucleolar accumulation of poly(A)(+) RNA at the restrictive temperature in S. pombe, but the signals do not overlap with the fibrillarin-rich region of the nucleolus. Thus, we found that mog1(+) is required for the mitosis-to-interphase transition and a class of RNA metabolism. In our attempt to identify suppressors of mog1-1, we isolated the spi1(+) gene, which encodes the fission yeast homologue of Ran. We found that overexpression of Spi1p rescues the S. pombe Delta mog1 cells from death. On the basis of these results, we conclude that mog1(+) is involved in the Ran-GTPase system.

  9. Cationic peptides as RNA compaction agents: a study on the polyA compaction activity of a linear alpha,epsilon-oligo-L-lysine.

    Science.gov (United States)

    Roviello, Giovanni N; Musumeci, Domenica; Roviello, Valentina

    2015-05-15

    In this work, we investigate the compaction activity of a sequential alpha,epsilon-peptide composed of l-lysines towards two RNA targets, in view of its possible pharmaceutical application in RNA-targeting and RNA delivery. The basic oligolysine, object of the present study, proved not only to be efficient in compacting the single-stranded polyA RNA, but also to strongly interact with the polyA·polyU complex, as evidenced by CD-binding and UV-melting experiments. In particular, the marked differences in the CD spectra of the RNA targets upon addition of the peptide, as well as the different UV melting behaviour for the polyA·polyU complex in the presence and absence of the peptide, sustain the hypothesis of a strong RNA compaction capacity of the alpha,epsilon-oligolysine. Finally, by using HPLC analysis, we found a good resistance of the peptide against the lytic action of human serum, an important requirement in view of in vitro/in vivo biological assays. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Electrokinetic remediation of copper mine tailings

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Rojo, Adrián; Ottosen, Lisbeth M.

    2007-01-01

    in similar experiments but without the bipolar electrodes. The new electrokinetic remediation design was tested on copper mine tailings with different applied electric fields, remediation times and pre-treatment. The results showed that the copper removal was increased from 8% (applying 20V for 8 days...... in sulphuric acidified tailings) without bipolar electrodes to 42% when bipolar electrodes were implemented. Furthermore, the results showed that in this system sulphuric acid addition prior to remediation was better than citric acid addition. In addition, applying a too strong electric field (even...

  11. Pioneer fauna of nepheline-containing tailings

    Science.gov (United States)

    Zenkova, I. V.; Kalmykova, V. V.; Liskovaya, A. A.

    2009-08-01

    The zoological analysis of nepheline-containing sands deposited in tailings 10-40 years ago showed that the pioneer colonists of this technogenic substrate are collembolan and mites, whose proportions depend on the succession of the bacterial and fungal components of the microbiota. The pioneer groups of mesofauna on 10- to 30-year-old tailings include carnivorous herpetobiontic arthropods and phytophagous insects. An impoverished version of the fauna of northern-taiga podzols is developed in the sands rehabilitated more than 40 years ago.

  12. Dynamics of Histone Tails within Chromatin

    Science.gov (United States)

    Bernier, Morgan; North, Justin; Page, Michael; Jaroniec, Christopher; Hammel, Christopher; Poirier, Michael

    2012-02-01

    Genetic information in humans is encoded within DNA molecules that is wrapped around histone octamer proteins and compacted into a highly conserved structural polymer, chromatin. The physical and material properties of chromatin appear to influence gene expression by altering the accessibility of proteins to the DNA. The tails of the histones are flexible domains that are thought to play a role in regulating DNA accessibility and compaction; however the molecular mechanisms for these phenomena are not understood. I will present CW-EPR studies on site directed spin labeled nucleosomes that probe the structure and dynamics of these histone tails within nucleosomes.

  13. Heavy-tailed chiral random matrix theory

    CERN Document Server

    Kanazawa, Takuya

    2016-01-01

    We study an unconventional chiral random matrix model with a heavy-tailed probabilistic weight. The model is shown to exhibit chiral symmetry breaking with no bilinear condensate, in analogy to the Stern phase of QCD. We solve the model analytically and obtain the microscopic spectral density and the smallest eigenvalue distribution for an arbitrary number of flavors and arbitrary quark masses. Exotic behaviors such as non-decoupling of heavy flavors and a power-law tail of the smallest eigenvalue distribution are illustrated.

  14. Radial tail resolution in the SELEX RICH

    Energy Technology Data Exchange (ETDEWEB)

    Morelos, A. [Universidad Autonoma de San Luis Potosi (Mexico)]. E-mail: morelos@ifisica.uaslp.mx; Mata, J. [Universidad Autonoma de San Luis Potosi (Mexico); Cooper, P.S. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Engelfried, J. [Universidad Autonoma de San Luis Potosi (Mexico); Aguilera-Servin, J.L. [Universidad Autonoma de San Luis Potosi (Mexico)

    2005-11-11

    We use a seven million event data sample of 600GeV/c single-track pion events, where the pion track is reconstructed upstream and downstream of the SELEX RICH. We build the RICH ring radius histogram distribution and count the tail events that fall outside 5{sigma}, giving a fraction of 4x10{sup -5} events outside the Gaussian tails. This control of events establishes the ability of using the RICH as a velocity spectrometer for high-precision searches of the K{sup +}->{pi}{sup +}{nu}{nu}-bar decay like it is planned in the CKM experiment.

  15. Radial tail resolution in the SELEX RICH

    Science.gov (United States)

    Morelos, A.; Mata, J.; Cooper, P. S.; Engelfried, J.; Aguilera-Servin, J. L.

    2005-11-01

    We use a seven million event data sample of 600 GeV/c single-track pion events, where the pion track is reconstructed upstream and downstream of the SELEX RICH. We build the RICH ring radius histogram distribution and count the tail events that fall outside 5σ, giving a fraction of 4×10-5 events outside the Gaussian tails. This control of events establishes the ability of using the RICH as a velocity spectrometer for high-precision searches of the K+→π+ ν ν¯ decay like it is planned in the CKM experiment.

  16. Radial tail resolution in the SELEX RICH

    Energy Technology Data Exchange (ETDEWEB)

    Morelos, A.; Mata, J.; Cooper, P.S.; Engelfried, J.; Aguilera-Servin, J.L.; /San Luis Potosi U. /Fermilab

    2005-01-01

    The authors use a 7 Million event data sample of 600 GeV/c single track pion events, where the pion track is reconstructed upstream and downstream of the SELEX RICH. They build the RICH ring radius histogram distribution and count the tail events that fall outside 5{sigma}, giving a fraction of 4 x 10{sup -5} events outside the Gaussian tails. This control of events establishes the ability of using the RICH as velocity spectrometer for high precision searches of the K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}} decay like it is planned in the CKM experiment.

  17. Heavy-tailed chiral random matrix theory

    Science.gov (United States)

    Kanazawa, Takuya

    2016-05-01

    We study an unconventional chiral random matrix model with a heavy-tailed probabilistic weight. The model is shown to exhibit chiral symmetry breaking with no bilinear condensate, in analogy to the Stern phase of QCD. We solve the model analytically and obtain the microscopic spectral density and the smallest eigenvalue distribution for an arbitrary number of flavors and arbitrary quark masses. Exotic behaviors such as non-decoupling of heavy flavors and a power-law tail of the smallest eigenvalue distribution are illustrated.

  18. Superiority of Filtered Tailings Storage Facility to Conventional Tailings Impoundment in Southern Rainy Regions of China

    Directory of Open Access Journals (Sweden)

    Shuai Li

    2016-11-01

    Full Text Available In order to evaluate the superiority of a filtered tailings storage facility (FTSF to conventional tailings impoundment in the southern rainy regions of China (SRRC, the tailings slurry leakage and pollution accident occurring at the wet tailings dam (WTD of Yinshan were analyzed, the properties of the tailings were tested in a laboratory, and the possibility of tailings liquefaction was evaluated. Comparisons of the slope stabilities of the filtered tailings dam (FTD and WTD in normal operation, flood, continuous rainfall, and earthquake situations were simulated using the Slide software. The results show that the FTD has less chance of seepage, lower failure probability, and limited potential destructiveness than the WTD with average slope safety factors of 2.120 for normal operation, 1.919 for flooding, 1.204 for continuous rainfall, and 1.724 for a magnitude-6.0 earthquake. The disaster chain model of the WTD of Yinshan belongs to the bursting and slippage chain. As the most safe and effective active prevention measure, the FTSF has the advantages of saving water, protecting the environment, improving its stability in flood and rainfall situations, and reducing the dam failure probability and potential losses, which is greatly applicable to the SRRC.

  19. Head/tail Breaks: A New Classification Scheme for Data with a Heavy-tailed Distribution

    CERN Document Server

    Jiang, Bin

    2012-01-01

    This paper introduces a new classification scheme - head/tail breaks - in order to find groupings or hierarchy for data with a heavy-tailed distribution. The heavy-tailed distributions are heavily right skewed, with a minority of large values in the head and a majority of small values in the tail, commonly characterized by a power law, a lognormal or an exponential function. For example, a country's population is often distributed in such a heavy-tailed manner, with a minority of people (e.g., 20 percent) in the countryside and the vast majority (e.g., 80 percent) in urban areas. This heavy-tailed distribution is also called scaling, hierarchy or scaling hierarchy. This new classification scheme partitions all of the data values around the mean into two parts and continues the process iteratively for the values (above the mean) in the head until the head part values are no longer heavy-tailed distributed. Thus, the number of classes and the class intervals are both naturally determined. We therefore claim tha...

  20. Exact and efficient simulation of tail probabilities of heavy-tailed infinite series

    OpenAIRE

    Hult, Henrik; Juneja, Sandeep; Murthy, Karthyek

    2016-01-01

    We develop an efficient simulation algorithm for computing the tail probabilities of the infinite series $S = \\sum_{n \\geq 1} a_n X_n$ when random variables $X_n$ are heavy-tailed. As $S$ is the sum of infinitely many random variables, any simulation algorithm that stops after simulating only fixed, finitely many random variables is likely to introduce a bias. We overcome this challenge by rewriting the tail probability of interest as a sum of a random number of telescoping terms, and subsequ...

  1. EAR AND TAIL LESIONS ON CAPTIVE WHITE-TAILED DEER FAWNS (ODOCOILEUS VIRGINIANUS): A CASE STUDY.

    Science.gov (United States)

    Ferguson, Treena L; Demarais, Stephen; Cooley, Jim; Fleming, Sherrill; Michel, Eric S; Flinn, Emily

    2016-06-01

    During the 2008-2011 time period, undiagnosed lesions were observed in 21 of 150 white-tailed deer fawns (Odocoileus virginianus) that were part of a captive deer herd at Mississippi State University. Clinical findings in healthy and diseased fawns from 0 to 90 days of age included bite and scratch marks followed by moderate to severe ear and tail necrosis. Gross necropsy findings of necrotizing ulcerative dermatitis correlated with histopathologic findings that included focally severe multifocal vasculitis, vascular necrosis, and thrombosis. This article is a clinical description of these previously unreported lesions associated with tissue necrosis in young captive white-tailed deer.

  2. Mine Waste Technology Program Electrochemical Tailings Cover

    Science.gov (United States)

    This report summarizes the results of Mine Waste Technology Program (MWTP) Activity III, Project 40, Electrochemical Tailings Cover, funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U.S. Department of Energy (DOE). MSE Technology A...

  3. Aircraft with Forward Sweeping T-Tail

    Science.gov (United States)

    Suciu, Gabriel L. (Inventor); Chandler, Jesse M. (Inventor)

    2017-01-01

    An aircraft includes a propulsor supported within an aft portion of the fuselage. A thrust reverser is supported proximate the propulsor for redirecting thrust forward to slow the aircraft upon landing. A tail extending from the aft portion of the fuselage is angled forward away from the aft portion and out of the discharge of airflow from the thrust reverser.

  4. Electrokinetic remediation of copper mine tailings

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Rojo, Adrián; Ottosen, Lisbeth M.

    2007-01-01

    in sulphuric acidified tailings) without bipolar electrodes to 42% when bipolar electrodes were implemented. Furthermore, the results showed that in this system sulphuric acid addition prior to remediation was better than citric acid addition. In addition, applying a too strong electric field (even...

  5. DNA isolation from rat tail or ear

    NARCIS (Netherlands)

    Cuppen, E.

    2010-01-01

    This protocol describes a rapid procedure for isolating DNA from rat tail or ear punches. The simplest version of the protocol can be scaled for use in 96-well (deep-well) plates. The quality of the DNA is sufficient for any polymerase chain reaction (PCR)-based genotyping approach.

  6. Analysis of biplane flapping flight with tail

    NARCIS (Netherlands)

    Tay, W.B.; Bijl, H.; Van Oudheusden, B.W.

    2012-01-01

    Numerical simulations have been performed to examine the interference effects between an upstream flapping biplane airfoil arrangement and a downstream stationary tail at a Reynolds number of 1000, which is around the regime of small flapping micro aerial vehicles. The objective is to investigate th

  7. The tail index of exchange rate returns

    NARCIS (Netherlands)

    C.G. Koedijk (Kees); M. Schafgans (Marcia); C.G. de Vries (Casper)

    1990-01-01

    textabstractIn the literature on the empirical distribution of foreign exchange rates there is now consensus that exchange rate yields are fat-tailed. Three problems, however, persist: (1) Which class of distribution functions is most appropriate? (2) Are the parameters of the distribution invariant

  8. Equilibrium Tail Distribution Due to Touschek Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Nash,B.; Krinsky, S.

    2009-05-04

    Single large angle Coulomb scattering is referred to as Touschek scattering. In addition to causing particle loss when the scattered particles are outside the momentum aperture, the process also results in a non-Gaussian tail, which is an equilibrium between the Touschek scattering and radiation damping. Here we present an analytical calculation for this equilibrium distribution.

  9. Functional morphology of the aardvark tail.

    Science.gov (United States)

    Endo, H; Mori, K; Koyabu, D; Kawada, S; Komiya, T; Itou, T; Koie, H; Kitagawa, M; Sakai, T

    2013-04-01

    The musculoskeletal system of the aardvark (Orycteropus afer) tail was morphologically examined in two adult specimens. The tail musculature comprised three muscular groups, viz. a dorsal sacrocaudal system that consisted of the irregularly oriented Musculus sacrocaudalis dorsalis medialis and M. sacrocaudalis dorsalis lateralis, a lateral inter-vertebral connecting system, and a ventral sacrocaudal system characterized by the thick M. sacrocaudalis ventralis lateralis and M. sacrocaudalis ventralis medialis. Both the dorsal and ventral systems possessed large tendon groups that strengthened the tail structure. Computed tomography (CT) examination showed the presence of large but homogeneous cartilaginous inter-vertebral discs, whereas V-shaped bones were situated at the ventral aspect of the caudal vertebrae at the level of the inter-vertebral discs. CT visualization of the tendons and V-shaped bones in various tail positions suggested that these structures contribute to the tunnel digging action by bearing the trunk weight and lending force when the aardvark are displacing the soil by means of the forelimbs.

  10. Vascularized tail bone grafts in rats.

    Science.gov (United States)

    Sempuku, T; Tamai, S; Mizumoto, S; Yajima, H

    1993-03-01

    A new experimental model for vascularized corticocancellous bone grafts was established by investigation of vascular anatomy of the tail in 15 adult Fischer 344 rats and determination of the viability of vascularized tail bone grafts into the abdominal wall in 22 7-week-old rats. The tail bones of 40 rats were then raised on the pedicle of the caudal artery and its venae comitantes, transferred to a resected portion in the femur, and observed for 16 weeks. The vascularized graft showed marked reactive periosteal bone formation during the first and second weeks following transfer, and thereafter, the graft continued to show active bone formation. In transverse section, the sharp processes became rounded. In the cancellous bone, both bone resorption and bone formation were noticeably activated early after transfer, although resorption predominated and the amount of the cancellous bone consequently diminished. The nonvascularized grafts showed "creeping substitution." The results suggest that morphologic adaptation occurs if living (i.e., vascularized) tail bones are transferred to long-bone femurs.

  11. Electrokinetic remediation of copper mine tailings

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, H. K.; Rojo, A.; Ottosen, L. M.

    2009-07-01

    The heavy metal contamination from mining industry has become a growing problem both in chile and worldwide. This contamination includes large areas with soil pollution, contaminated rivers and continuous generation of mining waste deposits. The solid waste that will be analysed is mine tailings, which are the residual products after the flotation process in conventional sulphide copper mining. (Author)

  12. Experiments on a Tail-wheel Shimmy

    Science.gov (United States)

    Harling, R; Dietz, O

    1954-01-01

    Model tests on the "running belt" and tests with a full-scale tail wheel were made on a rotating drum as well as on a runway in order to investigate the causes of the undesirable shimmy phenomena frequently occurring on airplane tail wheels, and the means of avoiding them. The small model (scale 1:10) permitted simulation of the mass, moments of inertia, and fuselage stiffness of the airplane and determination of their influence on the shimmy, whereas by means of the larger model with pneumatic tires (scale 1:2) more accurate investigations were made on the tail wheel itself. The results of drum and road tests show good agreement with one another and with model values. Detailed investigations were made regarding the dependence of the shimmy tendency on trail, rolling speed, load, size of tires, ground friction,and inclination of the swivel axis; furthermore, regarding the influence of devices with restoring effect on the tail wheel, and the friction damping required for prevention of shimmy. Finally observations from slow-motion pictures are reported and conclusions drawn concerning the influence of tire deformation.

  13. Mine Waste Technology Program Electrochemical Tailings Cover

    Science.gov (United States)

    This report summarizes the results of Mine Waste Technology Program (MWTP) Activity III, Project 40, Electrochemical Tailings Cover, funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U.S. Department of Energy (DOE). MSE Technology A...

  14. T-tail flutter analysis using Edge

    CSIR Research Space (South Africa)

    Van Zyl, Lourens H

    2011-11-01

    Full Text Available -tail. In reality, due to some a-symmetry in the grid, this was not quite achieved. The analyses consisted of a steady solution, followed by a prescribed, sine-squared, disturbance of 0.03 radians (corresponding to 10 mm lateral displacement at the fin top...

  15. DNA isolation from rat tail or ear

    NARCIS (Netherlands)

    Cuppen, E.

    2010-01-01

    This protocol describes a rapid procedure for isolating DNA from rat tail or ear punches. The simplest version of the protocol can be scaled for use in 96-well (deep-well) plates. The quality of the DNA is sufficient for any polymerase chain reaction (PCR)-based genotyping approach.

  16. Utilization of mine tailings as partial cement replacement

    DEFF Research Database (Denmark)

    Sigvardsen, Nina Marie; Nielsen, M.R.; Ottosen, Lisbeth M.

    2017-01-01

    Depositing mine tailings entail major economic costs and negative environmental impacts. Thus finding an alternative to depositing is of interest. This study focused on the use of mine tailings as partial cement replacement, thereby preventing depositing the mine tailings. At the same time......, such use would reduce the CO2 emission related to the production of cement. Mine tailings from two different mines Zinkgruvan (Sweden) and Nalunaq (Greenland) were both tested as 5 and 10 % cement replacement. All mortar specimens with mine tailings had lower compressive strength compared to a reference...... specimen at 7, 14 and 28 days of curing. Both mine tailings showed contributions to the pozzolanic activity. This tendency was more profound for Zinkgruvan. No evidence of either mine tailing containing minerals acting as nucleation sites was, however, seen. The specimens containing mine tailings were...

  17. Collecting Tail Hair Follicle for Bison DNA Sample

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — SOP guiding collection and processing of tail hair follicles from Bison for genetics analysis. Provides stepwise instructions and guidance on how to collect tail...

  18. Evaluating functions using tail recursion and parameter substitution

    Directory of Open Access Journals (Sweden)

    Georges E. Alfaro Salazar

    2016-03-01

    Full Text Available This article shows a general way to implement recursive functions calculation by linear tail recursion. It emphasizes the use of tail recursion to perform computations efficiently.

  19. Limits on the evolution of tail ornamentation in birds.

    Science.gov (United States)

    Evans, M R

    2004-03-01

    In birds, elongated tails are one of the most common and most studied ornaments. However, the tail also has an aerodynamic function, playing a role in turning and slow flight. If a tail is to function as an ornament, then there will be an inevitable conflict between the aerodynamic role and the signaling role. Aerodynamic theory has developed to the point where it is possible to predict the aerodynamic and mechanical consequences of ornamental tails of different sizes and shapes. Tail elongation will influence many different mechanical and aerodynamic parameters. For at least some and possibly all of these parameters, there will be limits that are placed by the bird's anatomy, morphology, or physiology on the extent to which the effect of tail elongation could be tolerated. For example, if a particular tail morphology meant that the power required to fly exceeded the power available from the flight muscles, then the bird would obviously be unable to fly with such a tail. To examine whether these considerations could limit the development of ornamental tails, the effect of long tails of different shapes was examined on three parameters: static balance, lift-to-drag ratio, and the cost of flight. All three of these parameters were found to limit the range of possible tail morphologies that could be developed by birds. These limits were most acute for small birds, which may not be able to operate with a long tail of any shape. Slightly larger birds would be able to develop elongated streamers and forked tails but not pintails or wedge-shaped tails. Medium to large birds are less constrained and could develop a much wider range of tails than small birds, but there will always be limits to the sizes of tail ornament that could be developed. Thus the physical consequences of ornamentation on ecology and behavior are likely to be responsible for some of the patterns of ornamentation observed in nature.

  20. Tail-assisted pitch control in lizards, robots and dinosaurs.

    Science.gov (United States)

    Libby, Thomas; Moore, Talia Y; Chang-Siu, Evan; Li, Deborah; Cohen, Daniel J; Jusufi, Ardian; Full, Robert J

    2012-01-04

    In 1969, a palaeontologist proposed that theropod dinosaurs used their tails as dynamic stabilizers during rapid or irregular movements, contributing to their depiction as active and agile predators. Since then the inertia of swinging appendages has been implicated in stabilizing human walking, aiding acrobatic manoeuvres by primates and rodents, and enabling cats to balance on branches. Recent studies on geckos suggest that active tail stabilization occurs during climbing, righting and gliding. By contrast, studies on the effect of lizard tail loss show evidence of a decrease, an increase or no change in performance. Application of a control-theoretic framework could advance our general understanding of inertial appendage use in locomotion. Here we report that lizards control the swing of their tails in a measured manner to redirect angular momentum from their bodies to their tails, stabilizing body attitude in the sagittal plane. We video-recorded Red-Headed Agama lizards (Agama agama) leaping towards a vertical surface by first vaulting onto an obstacle with variable traction to induce a range of perturbations in body angular momentum. To examine a known controlled tail response, we built a lizard-sized robot with an active tail that used sensory feedback to stabilize pitch as it drove off a ramp. Our dynamics model revealed that a body swinging its tail experienced less rotation than a body with a rigid tail, a passively compliant tail or no tail. To compare a range of tails, we calculated tail effectiveness as the amount of tailless body rotation a tail could stabilize. A model Velociraptor mongoliensis supported the initial tail stabilization hypothesis, showing as it did a greater tail effectiveness than the Agama lizards. Leaping lizards show that inertial control of body attitude can advance our understanding of appendage evolution and provide biological inspiration for the next generation of manoeuvrable search-and-rescue robots.

  1. Molecular tools for studying the major malaria vector Anopheles funestus: improving the utility of the genome using a comparative poly(A) and Ribo-Zero RNAseq analysis.

    Science.gov (United States)

    Weedall, Gareth D; Irving, Helen; Hughes, Margaret A; Wondji, Charles S

    2015-11-14

    Next-generation sequencing (NGS) offers great opportunities for studying the biology of insect vectors of disease. Prerequisites for successful analyses include high quality annotated genome assemblies and that techniques designed for use with model organisms be tested and optimised for use with these insects. We aimed to test and improve genomic tools for studying the major malaria vector Anopheles funestus. To guide future RNAseq transcriptomic studies of An. funestus, we compared two methods for enrichment of non-ribosomal RNA for analysis: enrichment of polyadenylated RNA and ribosomal RNA depletion using a kit designed to deplete human/rat/mouse rRNA. We found large differences between the two methods in the resulting transcriptomes, some of which is due to differential representation of polyadenylated and non-polyadenylated transcripts. We used the RNAseq data for validation and targeted manual editing of the draft An. funestus genome annotation, validating 62 % of annotated introns, manually improving the annotation of seven gene families involved in the detoxification of xenobiotics and integrated two published transcriptomic datasets with the recently published genome assembly. The mRNA enrichment method makes a substantial, replicable difference to the transcriptome composition, at least partly due to the representation of non-polyadenylated transcripts in the final transcriptome. Therefore, great care should be taken in comparing gene expression data among studies. Ribosomal RNA depletion of total RNA using a kit designed to deplete human/rat/mouse rRNA works in mosquitoes and, we argue, results in a truer representation of the transcriptome than poly(A) selection. The An. funestus genome annotation can be considerably improved with the help of these new RNAseq data and further guided manual gene editing efforts will be of great benefit to the Anopheles research community for studies of this insect's genome and transcriptome.

  2. Differential localization of the two T. brucei poly(A binding proteins to the nucleus and RNP granules suggests binding to distinct mRNA pools.

    Directory of Open Access Journals (Sweden)

    Susanne Kramer

    Full Text Available The number of paralogs of proteins involved in translation initiation is larger in trypanosomes than in yeasts or many metazoan and includes two poly(A binding proteins, PABP1 and PABP2, and four eIF4E variants. In many cases, the paralogs are individually essential and are thus unlikely to have redundant functions although, as yet, distinct functions of different isoforms have not been determined. Here, trypanosome PABP1 and PABP2 have been further characterised. PABP1 and PABP2 diverged subsequent to the differentiation of the Kinetoplastae lineage, supporting the existence of specific aspects of translation initiation regulation. PABP1 and PABP2 exhibit major differences in intracellular localization and distribution on polysome fractionation under various conditions that interfere with mRNA metabolism. Most striking are differences in localization to the four known types of inducible RNP granules. Moreover, only PABP2 but not PABP1 can accumulate in the nucleus. Taken together, these observations indicate that PABP1 and PABP2 likely associate with distinct populations of mRNAs. The differences in localization to inducible RNP granules also apply to paralogs of components of the eIF4F complex: eIF4E1 showed similar localization pattern to PABP2, whereas the localisation of eIF4E4 and eIF4G3 resembled that of PABP1. The grouping of translation initiation as either colocalizing with PABP1 or with PABP2 can be used to complement interaction studies to further define the translation initiation complexes in kinetoplastids.

  3. A novel nuclear-encoded mitochondrial poly(A polymerase PAPD1 is a potential candidate gene for the extreme obesity related phenotypes in mammals

    Directory of Open Access Journals (Sweden)

    Qianjun Xiao, Xiao-Lin Wu, Jennifer J. Michal, Jerry J. Reeves, Jan R. Busboom, Gary H. Thorgaard, Zhihua Jiang

    2006-01-01

    Full Text Available People with obesity, especially extreme obesity, are at risk for many health problems. However, the responsible genes remain unknown in >95% of severe obesity cases. Our previous genome-wide scan of Wagyu x Limousin F2 cattle crosses with extreme phenotypes revealed a molecular marker significantly associated with intramuscular fat deposition. Characterization of this marker showed that it is orthologous to the human gene KIAA1462 located on HSA10p11.23, where a major quantitative trait locus for morbid obesity has been reported. The newly identified mitochondrial poly(A polymerase associated domain containing 1 (PAPD1 gene, which is located near this marker, is particularly interesting because the polymerase is required for the polyadenylation and stabilization of mammalian mitochondrial mRNAs. In the present study, both cDNA and genomic DNA sequences were annotated for the bovine PAPD1 gene and ten genetic markers were detected in the promoter and exon 1 region. Among seven markers assayed on ~ 250 Wagyu x Limousin F2 animals, two single nucleotide polymorphisms (SNPs in the promoter region were significantly associated with intramuscular fat (P<0.05. However, there was a significant interaction (P<0.05 between a third SNP, which causes an amino acid change in coding exon 1, and each of these two promoter SNPs on intramuscular fat deposition. In particular, the differences between double heterozygous animals at two polymorphic sites and the slim genotype animals exceeded 2.3 standard deviations for the trait in both cases. Our study provides evidence for a new mechanism – the involvement of compound heterosis in extreme obesity, which warrants further examination.

  4. Systematic profiling of poly(A+ transcripts modulated by core 3' end processing and splicing factors reveals regulatory rules of alternative cleavage and polyadenylation.

    Directory of Open Access Journals (Sweden)

    Wencheng Li

    2015-04-01

    Full Text Available Alternative cleavage and polyadenylation (APA results in mRNA isoforms containing different 3' untranslated regions (3'UTRs and/or coding sequences. How core cleavage/polyadenylation (C/P factors regulate APA is not well understood. Using siRNA knockdown coupled with deep sequencing, we found that several C/P factors can play significant roles in 3'UTR-APA. Whereas Pcf11 and Fip1 enhance usage of proximal poly(A sites (pAs, CFI-25/68, PABPN1 and PABPC1 promote usage of distal pAs. Strong cis element biases were found for pAs regulated by CFI-25/68 or Fip1, and the distance between pAs plays an important role in APA regulation. In addition, intronic pAs are substantially regulated by splicing factors, with U1 mostly inhibiting C/P events in introns near the 5' end of gene and U2 suppressing those in introns with features for efficient splicing. Furthermore, PABPN1 inhibits expression of transcripts with pAs near the transcription start site (TSS, a property possibly related to its role in RNA degradation. Finally, we found that groups of APA events regulated by C/P factors are also modulated in cell differentiation and development with distinct trends. Together, our results support an APA code where an APA event in a given cellular context is regulated by a number of parameters, including relative location to the TSS, splicing context, distance between competing pAs, surrounding cis elements and concentrations of core C/P factors.

  5. Spectrum of human tails: A report of six cases

    Directory of Open Access Journals (Sweden)

    Biswanath Mukhopadhyay

    2012-01-01

    Full Text Available Human tail is a curiosity, a cosmetic stigma and presents as an appendage in the lumbosacral region. Six patients of tail in the lumbosacral region are presented here to discuss the spectrum of presentation of human tails. The embryology, pathology and treatment of this entity are discussed along with a brief review of the literature.

  6. Pareto tails and lognormal body of US cities size distribution

    Science.gov (United States)

    Luckstead, Jeff; Devadoss, Stephen

    2017-01-01

    We consider a distribution, which consists of lower tail Pareto, lognormal body, and upper tail Pareto, to estimate the size distribution of all US cities. This distribution fits the data more accurately than a distribution that comprises of only lognormal and the upper tail Pareto.

  7. Uranium Mill Tailings Remedial Action Project surface project management plan

    Energy Technology Data Exchange (ETDEWEB)

    1994-09-01

    This Project Management Plan describes the planning, systems, and organization that shall be used to manage the Uranium Mill Tailings Remedial Action Project (UMTRA). US DOE is authorized to stabilize and control surface tailings and ground water contamination at 24 inactive uranium processing sites and associated vicinity properties containing uranium mill tailings and related residual radioactive materials.

  8. Electro-remediation of copper mine tailings. Comparing copper removal efficiencies for two tailings of different age

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Lamas, Victor; Gutierrez, Claudia;

    2013-01-01

    less than 2 years ago (new tailings). Parameters analyzed were the applied voltage drop, acid concentration during pretreatment, and the use of either passive or ion exchange membranes in the experimental setup. The comparison of the results confirms that there are differences in the electroremediation...... between the two tailings, even if the pH is similar and a mineralogical analysis showed similarities between the samples with respect to composition. It was found that an electroremediation is more favorable on the old tailings. The results showed that the best experimental conditions for both tailings......This work compares and evaluates the copper removal efficiency when applying electric fields to two mine tailings originating from the same mine but of different age. Eight experiments were carried out - four on tailings deposited more than 20 years ago (old tailings) and four on tailings deposited...

  9. Networks with superfat-tailed degree distributions

    CERN Document Server

    Timár, Gábor; Mendes, José Fernando F

    2016-01-01

    A majority of studied models for scale-free networks have degree distributions with exponents greater than $2$. Real networks, however, can demonstrate essentially more heavy-tailed degree distributions. We explore two models of scale-free equilibrium networks that have the degree distribution exponent $\\gamma = 1$, $P(q) \\sim q^{-\\gamma}$. Such "superfat-tailed" degree distributions can be identified in empirical data only if the mean degree of a network is sufficiently high. Our models exploit a rewiring mechanism. They are local in the sense that no knowledge of the network structure, apart from the immediate neighbourhood of the vertices, is required. These models generate uncorrelated networks in the infinite size limit, where they are solved explicitly. We investigate finite size effects by the use of simulations. We find that both models exhibit disassortative degree-degree correlations for finite network sizes. In addition, we observe a markedly degree-dependent clustering in the finite networks. We i...

  10. Universality of Tail Exponents of Price Changes?

    Science.gov (United States)

    Huang, Luwen; Farmer, Doyne

    2007-03-01

    We study the tail exponents of the distribution of logarithmic price changes in financial markets, and investigate the conjecture that they are universal with an exponent near three. Using data from the London Stock Exchange, we construct the empirical distributions of price returns on several different time scales and study their variation as a function of parameters such as trading volume and tick size (the minimal unit of price variation).

  11. Forecast Combination under Heavy-Tailed Errors

    Directory of Open Access Journals (Sweden)

    Gang Cheng

    2015-11-01

    Full Text Available Forecast combination has been proven to be a very important technique to obtain accurate predictions for various applications in economics, finance, marketing and many other areas. In many applications, forecast errors exhibit heavy-tailed behaviors for various reasons. Unfortunately, to our knowledge, little has been done to obtain reliable forecast combinations for such situations. The familiar forecast combination methods, such as simple average, least squares regression or those based on the variance-covariance of the forecasts, may perform very poorly due to the fact that outliers tend to occur, and they make these methods have unstable weights, leading to un-robust forecasts. To address this problem, in this paper, we propose two nonparametric forecast combination methods. One is specially proposed for the situations in which the forecast errors are strongly believed to have heavy tails that can be modeled by a scaled Student’s t-distribution; the other is designed for relatively more general situations when there is a lack of strong or consistent evidence on the tail behaviors of the forecast errors due to a shortage of data and/or an evolving data-generating process. Adaptive risk bounds of both methods are developed. They show that the resulting combined forecasts yield near optimal mean forecast errors relative to the candidate forecasts. Simulations and a real example demonstrate their superior performance in that they indeed tend to have significantly smaller prediction errors than the previous combination methods in the presence of forecast outliers.

  12. Radiation hazard of solid metallic tailings in Shangluo, China

    Directory of Open Access Journals (Sweden)

    Zhuang Sukai

    2016-01-01

    Full Text Available The radiation hazards of five kinds of different solid metallic tailings collected from Shangluo, China were determined on the basis of natural radioactivity measurements using low background multichannel gamma ray spectrometry. The activity concentration of 226Ra, 232Th and 40K in the tailings ranged from 5.1 to 204.3, 3.8 to 28.5, and 289.6 to 762.3 Bq/kg, respectively. The radium equivalent activities and the external hazard indexes of all studied metallic tailings were below the internationally accepted value of 370 Bq/kg and unity, respectively. The internal hazard index of vanadium tailings exceeded unity, while the internal hazard indexes of other analyzed metallic tailings were less than unity. The indoor air absorbed dose rate values for all studied metallic tailings except lead-zinc tailings and gold tailings were higher than the world population-weighted average of 84 nGy/h and the annual effective dose values of all metallic tailings except for vanadium tailings were lower than 1 mSv. The study showed that vanadium tailings present a radiation hazard and their usage as building materials should be restricted.

  13. The relationship between infection and the tailed IUD.

    Science.gov (United States)

    Jin, B H; Wu, Y H; Pan, X H

    1997-01-01

    To clarify the association between the tailed IUD and pelvic infection, vaginal smears from 111 Chinese IUD users (40 acceptors of tailed IUDs and 71 of tailless devices) were analyzed for bacterial microorganisms. All study subjects had used the IUD for at least 5 years. Of the 11 samples positive for bacteria taken from the internal os, eight were from users of tailed IUDs (p 0.01). Of the 7 positive samples taken from the uterine cavity, 5 were linked to a tailed device. Although the correlation between the tailed IUD and pelvic symptoms was not significant, infected users of the tailed device were slightly more likely to be symptomatic. The tailed IUD did not increase leukorrhea excretion.

  14. A Note on Upper Tail Behavior of Liouville Copulas

    Directory of Open Access Journals (Sweden)

    Lei Hua

    2016-11-01

    Full Text Available The family of Liouville copulas is defined as the survival copulas of multivariate Liouville distributions, and it covers the Archimedean copulas constructed by Williamson’s d-transform. Liouville copulas provide a very wide range of dependence ranging from positive to negative dependence in the upper tails, and they can be useful in modeling tail risks. In this article, we study the upper tail behavior of Liouville copulas through their upper tail orders. Tail orders of a more general scale mixture model that covers Liouville distributions is first derived, and then tail order functions and tail order density functions of Liouville copulas are derived. Concrete examples are given after the main results.

  15. Ecological aspects of microorganisms inhabiting uranium mill tailings.

    Science.gov (United States)

    Miller, C L; Landa, E R; Updegraff, D M

    1987-09-01

    Numbers and types of microorganisms in uranium mill tailings were determined using culturing techniques.Arthrobacter were found to be the predominant microorganism inhabiting the sandy tailings, whereasBacillus and fungi predominated in the slime tailings. Sulfate-reducing bacteria, capable of leaching radium, were isolated in low numbers from tailings samples but were isolated in significantly high numbers from topsoil in contact with the tailings. The results are placed in the context of the magnitude of uranium mill tailings in the United States, the hazards posed by the tailings, and how such hazards could be enhanced or diminished by microbial activities. Patterns in the composition of the microbial population are evaluated with respect to the ecological variables that influence microbial growth.

  16. Accelerated weathering of biosolid-amended copper mine tailings.

    Science.gov (United States)

    Pond, Andrew P; White, Scott A; Milczarek, Michael; Thompson, Thomas L

    2005-01-01

    Application of municipal biosolids to mine tailings can enhance revegetation success, but may cause adverse environmental impacts, such as increased leaching of NO3- and metals to ground water. Kinetic weathering cells were used to simulate geochemical weathering to determine the effects of biosolid amendment on (i) pH of leachate and tailings, (ii) leaching of NO3- and SO4(2-), (iii) leaching and bioavailability (DTPA-extractable) of selected metals, and (iv) changes in tailing mineralogy. Four Cu mine tailings from southern Arizona differing in initial pH (3.3-7.3) and degree of weathering were packed into triplicate weathering cells and were unamended and amended with two rates (equivalent to 134 and 200 Mg dry matter ha(-1)) of biosolids. Biosolid application to acid (pH 3.3) tailings resulted in pH values as high as 6.3 and leachate pH as high as 5.7, and biosolids applied to circumneutral tailings resulted in no change in tailing or leachate pH. Concentrations of NO3--N of up to 23 mg L(-1) occurred in leachates from circumneutral tailings. The low pH of the acidic tailing apparently inhibited nitrification, resulting in leachate NO3--N of tailings (final rate of 0.04 compared with 0.11 g SO4(2-)-S wk(-1)). Copper concentrations in leachates from acidic tailings were reduced from 53 to 27 mg L(-1) with biosolid amendment. Copper and As concentrations increased slightly in leachates from biosolid-amended circumneutral tailings. Small increases in DTPA-extractable Cu, Ni, and Zn occurred in all tailings with increased biosolid rate. Overall, there was little evidence of potential for adverse environmental impacts resulting from biosolid application to these Cu mine tailings.

  17. Permeability Characteristics of Tailings considering Chemical and Physical Clogging in Lixi Tailings Dam, China

    Directory of Open Access Journals (Sweden)

    Zengguang Xu

    2016-01-01

    Full Text Available Chemical and physical clogging frequently occur in tailings dam. The clogging seriously influences the safety of tailings dam. This paper conducts several column experiments to analyse the physical and chemical clogging of the Lixi tailings dam in China. The experiment results of chemical clogging show that average flow velocity and permeability decrease by approximately 50% to 60%. The experiment results of physical clogging show that these values decrease by approximately 50% to 70%. For physical clogging, a higher hydraulic gradient could result in a larger extent of decrease in the permeability coefficient. The permeability did not decrease when the hydraulic gradient was equal to 0.125. The results of chemical clogging column experiments show that ferrous ion solution concentration is disproportional to the permeability coefficient. This scenario can be attributed to the extremely small concentration gradients.

  18. mRNA decay proteins are targeted to poly(A+ RNA and dsRNA-containing cytoplasmic foci that resemble P-bodies in Entamoeba histolytica.

    Directory of Open Access Journals (Sweden)

    Itzel López-Rosas

    Full Text Available In higher eukaryotes, mRNA degradation and RNA-based gene silencing occur in cytoplasmic foci referred to as processing bodies (P-bodies. In protozoan parasites, the presence of P-bodies and their putative role in mRNA decay have yet to be comprehensively addressed. Identification of P-bodies might provide information on how mRNA degradation machineries evolved in lower eukaryotes. Here, we used immunofluorescence and confocal microscopy assays to investigate the cellular localization of mRNA degradation proteins in the human intestinal parasite Entamoeba histolytica and found evidence of the existence of P-bodies. Two mRNA decay factors, namely the EhXRN2 exoribonuclease and the EhDCP2 decapping enzyme, were localized in cytoplasmic foci in a pattern resembling P-body organization. Given that amoebic foci appear to be smaller and less rounded than those described in higher eukaryotes, we have named them "P-body-like structures". These foci contain additional mRNA degradation factors, including the EhCAF1 deadenylase and the EhAGO2-2 protein involved in RNA interference. Biochemical analysis revealed that EhCAF1 co-immunoprecipitated with EhXRN2 but not with EhDCP2 or EhAGO2-2, thus linking deadenylation to 5'-to-3' mRNA decay. The number of EhCAF1-containing foci significantly decreased after inhibition of transcription and translation with actinomycin D and cycloheximide, respectively. Furthermore, results of RNA-FISH assays showed that (i EhCAF1 colocalized with poly(A(+ RNA and (ii during silencing of the Ehpc4 gene by RNA interference, EhAGO2-2 colocalized with small interfering RNAs in cytoplasmic foci. Our observation of decapping, deadenylation and RNA interference proteins within P-body-like foci suggests that these structures have been conserved after originating in the early evolution of eukaryotic lineages. To the best of our knowledge, this is the first study to report on the localization of mRNA decay proteins within P

  19. Asymptotic Results for Tail Probabilities of Sums of Dependent and Heavy-Tailed Random Variables

    Institute of Scientific and Technical Information of China (English)

    Kam Chuen YUEN; Chuancun YIN

    2012-01-01

    Abstract Let X1,X2,...be a sequence of dependent and heavy-tailed random variables with distributions F1,F2,…. on (-∞,∞),and let т be a nonnegative integer-valued random variable independent of the sequence {Xk,k≥ 1}.In this framework,the asymptotic behavior of the tail probabilities of the quantities Sn =n∑k=1 Xk and S(n) =max1≤k≤n Sk for n > 1,and their randomized versions Sт and S(т) are studied.Some applications to the risk theory are presented.

  20. Metal mobilization under alkaline conditions in ash-covered tailings.

    Science.gov (United States)

    Lu, Jinmei; Alakangas, Lena; Wanhainen, Christina

    2014-06-15

    The aim of this study was to determine element mobilization and accumulation in mill tailings under alkaline conditions. The tailings were covered with 50 cm of fly ash, and above a sludge layer. The tailings were geochemically and mineralogically investigated. Sulfides, such as pyrrhotite, sphalerite and galena along with gangue minerals such as dolomite, calcite, micas, chlorite, epidote, Mn-pyroxene and rhodonite were identified in the unoxidized tailings. The dissolution of the fly ash layer resulted in a high pH (close to 12) in the underlying tailings. This, together with the presence of organic matter, increased the weathering of the tailings and mobilization of elements in the uppermost 47 cm of the tailings. All primary minerals were depleted, except quartz and feldspar which were covered by blurry secondary carbonates. Sulfide-associated elements such as Cd, Fe, Pb, S and Zn and silicate-associated elements such as Fe, Mg and Mn were released from the depletion zone and accumulated deeper down in the tailings where the pH decreased to circum-neutral. Sequential extraction suggests that Cd, Cu, Fe, Pb, S and Zn were retained deeper down in the tailings and were mainly associated with the sulfide phase. Calcium, Cr, K and Ni released from the ash layer were accumulated in the uppermost depletion zone of the tailings. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Tailings philosophies : to segregate or not to segregate

    Energy Technology Data Exchange (ETDEWEB)

    Wells, P.S. [Suncor Energy, Fort McMurray, AB (Canada)

    2010-07-01

    Traditional technologies for treating oil sands tailings include the segregation of of tailings when discharged into water-filled ponds. The coarser tailings form long beaches. However, the percentage of silts and clays that remain suspended within the water column pose significant challenges to oil sands operators, and contribute to water losses and increases in storage volume. This paper discussed new technologies developed to identify the tailings materials that contribute to the problem and methods designed to isolate and treat the materials. Treatment material balances, process water balances, and material handling requirements for the technologies were evaluated and compared. Three scenarios were considered: (1) a sub-aqueous beaching scenario where tailings were produced by extraction and pumped to a beach storage area for dewatering through self-drainage; (2) a non-segregated tailings (NST) scenario that used mature fine tailings (MFT) drying; (3) and a segregated stream scenario where MFT drying was used where tailings were deposited in traditional tailings ponds. Results of the study showed that the segregated stream tailings treatment system was preferred to NST treatment system. Options for sub-aerial NST deposition may overcome the volume discrepancies between treating fines as well as the required volumes of coarser materials. 5 refs., 2 tabs., 2 figs.

  2. Oil sands tailings technology : understanding the impact to reclamation

    Energy Technology Data Exchange (ETDEWEB)

    Mamer, M. [Suncor Energy Inc., Fort McMurray, AB (Canada)

    2010-07-01

    This paper discussed tailings management techniques at oil sands mines and their effects on reclamation schedules and outcomes. The layer of mature fine tailings (MFT) that forms in tailings ponds does not settle within a reasonable time frame, requiring more and larger tailings ponds for storing MFT. Consolidated tailings (CT) technology was developed to accelerate the consolidation of MFT, although the process nonetheless takes decades. CT is produced from mixing tailings sand, gypsum, and MFT to create a mixture that will consolidate more quickly and release water. However, CT production is tied to the extraction process, making it applicable only when the plant is operational, and a precise recipe and accurate injection are required for CT to work. In tailings reduction operations (TRO), a new approach to tailings management, MFT is mixed with a polymer flocculant, deposited in thin layers, and allowed to dry. TRO has a significant advantage over CT in that the latter takes up to 30 years to consolidate to a trafficable surface compared to weeks for TRO. TRO allows MFT to be consumed more quickly than it is produced, reducing need to build more tailings ponds, operates independent of plant operations, accelerates the reclamation time frame, and offers enhanced flexibility in final tailings placement sites. TRO also creates a dry landscape, to which well established reclamation techniques can be applied. Dried MFT is a new material type, and research is exploring optimum reclamation techniques. 2 figs.

  3. Phytomining for Artisanal Gold Mine Tailings Management

    Directory of Open Access Journals (Sweden)

    Baiq Dewi Krisnayanti

    2016-08-01

    Full Text Available Mine tailings are generally disposed of by artisanal and small scale gold miners in poorly constructed containment areas and this leads to environmental risk. Gold phytomining could be a possible option for tailings management at artisanal and small-scale gold mining (ASGM locations where plants accumulate residual gold in their above ground biomass. The value of metal recovered from plants could offset some of the costs of environmental management. Getting gold into plants has been repeatedly demonstrated by many research groups; however, a simple working technology to get gold out of plants is less well described. A field experiment to assess the relevance of the technology to artisanal miners was conducted in Central Lombok, Indonesia between April and June 2015. Tobacco was planted in cyanidation tailings (1 mg/kg gold and grown for 2.5 months before the entire plot area was irrigated with NaCN to induce metal uptake. Biomass was then harvested (100 kg, air dried, and ashed by miners in equipment currently used to ash activated carbon at the end of a cyanide leach circuit. Borax and silver as a collector metal were added to the tobacco ash and smelted at high temperature to extract metals from the ash. The mass of the final bullion (39 g was greater than the mass of silver used as a collector (31 g, indicating recovery of metals from the biomass through the smelt process. The gold yield of this trial was low (1.2 mg/kg dry weight biomass concentration, indicating that considerable work must still be done to optimise valuable metal recovery by plants at the field scale. However, the described method to process the biomass was technically feasible, and represents a valid technique that artisanal and small-scale gold miners are willing to adopt if the economic case is good.

  4. A Farey tail for attractor black holes

    Science.gov (United States)

    de Boer, Jan; Cheng, Miranda C. N.; Dijkgraaf, Robbert; Manschot, Jan; Verlinde, Erik

    2006-11-01

    The microstates of 4d BPS black holes in IIA string theory compactified on a Calabi-Yau manifold are counted by a (generalized) elliptic genus of a (0,4) conformal field theory. By exploiting a spectral flow that relates states with different charges, and using the Rademacher formula, we find that the elliptic genus has an exact asymptotic expansion in terms of semi-classical saddle-points of the dual supergravity theory. This generalizes the known "Black Hole Farey Tail" of [1] to the case of attractor black holes.

  5. A Farey Tail for Attractor Black Holes

    CERN Document Server

    De Boer, J; Dijkgraaf, R; Manschot, J; Verlinde, E; Boer, Jan de; Cheng, Miranda C.N.; Dijkgraaf, Robbert; Manschot, Jan; Verlinde, Erik

    2006-01-01

    The microstates of 4d BPS black holes in IIA string theory compactified on a Calabi-Yau manifold are counted by a (generalized) elliptic genus of a (0,4) conformal field theory. By exploiting a spectral flow that relates states with different charges, and using the Rademacher formula, we find that the elliptic genus has an exact asymptotic expansion in terms of semi-classical saddle-points of the dual supergravity theory. This generalizes the known "Black Hole Farey Tail" of [1] to the case of attractor black holes.

  6. Probing the long tail of the magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, R.A.

    1984-12-14

    Using data from the International Sun-Earth Explorer Spacecraft (ISEE-3), researchers have studied the structure of the magnetotail and its behavior. In the plasma sheet of the distant tail, ISEE-3 found plasma flowing tailward as fast as 1000 Km/sec. An ISEE-3 group at Los Alamos National Laboratory has offered an explanation of the high plasma speeds that addresses how the magnetosphere stores and ultimately rids itself of the charged particles and magnetic fields that it picks up from the solar wind. According to this group the high tailward plasma sheet flows are driven by a process called magnetic reconnection.

  7. Scientists Explain Catalysis Neutralizing Car's Tail Gas

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ The neutralization of the car's tail gas is a problem of practical importance in the eyes of both experimental and theoretical physicists. Recently, a group of CAS scientists join hands with the Queen's University of Belfast in the UK to make advances in exploring the process of CO oxidation in a bid to reduce the air pollution caused by the car's exhaust gas. The work has been supported by the "National 973Program" and the CAS Foundation for Overseas Studies. On March 4,its result was published by the Internet edition of the Journal of the American Chemical Society.

  8. Biogeochemistry of metalliferous mine tailings during phytostabilizatio

    Science.gov (United States)

    Chorover, J.; Root, R. A.; Hammond, C.; Wang, Y.; Maier, R. M.

    2015-12-01

    In the semi-arid southwest US, legacy mine tailings and the associated metal(loid) contaminants, are prone to wind dispersion and water erosion. Without remediation, tailings can remain barren for decades to centuries, providing a point source of toxic contamination. Successful mitigation of toxins (As, Pb) from fugitive dust is often limited to confinement and stabilization. Capping mine tailings with soil or gravel is an accepted, although expensive, strategy to reduce erosion. Revegetation via assisted direct planting (also known as phytostabilization) has the potential to be a cost-effective and self-sustaining alternative "green-technology" to expensive capping. The impact of phytostabilization, and requisite added organic carbon and irrigation on mechanisms of contaminant mobility is being investigated with concurrent highly-instrumented greenhouse mesocosms and in situ field studies using advanced microbiological tools and synchrotron x-ray based molecular probes. Composted treatments initially neutralized the near surface acid tailings (~2 to ~6.5). However, after 9 mo the mesocosms showed a gradual and eventual decrease back to pH 2. The exception was the root zone of Atriplex lentiformis, which buffered the acidic conditions for 12 months. Rhizosphere microbiota experienced a 5-log increase in the compost-amended compared to control greenhouse mesocosms. Weathering of the primary sulfidic mineral assemblage, indicated by the iron and sulfur speciation, was shown to control the mobility, speciation and bioavailability of both As and Pb via sequestration in (meta)stable neoformed jarosite phases as plumbojarosite and As(V) substituted for sulfate in hydronium jarosite, with important implications for human and environmental health risk management. We conclude that the disequilibrium imposed by phytostabilization results in an increase of heterotrophic biomass that is concurrent with a time series of geochemical transformations, which controls the species

  9. Azomesogens with methoxyethyl tail: Synthesis and characterization

    Indian Academy of Sciences (India)

    A K Prajapati; H M Pandya

    2005-05-01

    Two new mesogenic homologous series are synthesized from methoxyethyl 4-(4'-hydroxyphenylazo) benzoate. In series I the phenolic -OH group is alkylated, whereas in series II it is esterified with 4--alkoxybenzoyl group. In series I, all the nine members synthesized exhibit only enantiotropic smectic A mesophase. In series II, all the twelve homologues exhibit enantiotropic nematic mesophase. Smectic A mesophase appears from the -decyloxy derivative as a enantiotropic phase and persists till the last -hexadecyloxy member. The mesomorphic properties of both the series are compared with each other and also with the properties of other structurally related series to evaluate the effect of the methoxyethyl tail on mesomorphism.

  10. Paste and thickened tailings technology and its applicability in oil sand tailings management

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, X.S.; Lahaie, R. [Syncrude Canada Ltd., Fort McMurray, AB (Canada)

    2010-07-01

    Tailings management practices can have a significant impact on overall oil sands mining operations. Paste and thickened tailings (P and TT) technology is an integrated engineering system that includes a thickener feed preparation process, type selection, and process; a flocculant selection and technology development; P and TT transport, deposition, and consolidation; and a strategy for re-using thickener overflow water and reducing impacts to the environment. This paper discussed developments of P and TT technology in relation to fine oil sands tailings. Practical applications of P and TT technology in the mineral industry were discussed, as well as recent research and development work conducted by Syncrude. Pilot programs currently being conducted to determine optimal thickener hydraulic and solids loading rates were discussed as well as the results of experiments conducted to determine flocculation and sedimentation processes. Thin-lift dry stacking technologies and containment methods were reviewed. Environmental considerations related to closure, residual bitumen, and warm water return and heat recovery were discussed. The study concluded by suggesting that a suite of technologies is needed to address the varying geographical, surface area, and mine progression challenges related to tailings management. 28 refs., 3 tabs., 10 figs.

  11. Tidal Tails in Interacting Galaxies: Formation of Compact Stellar Structures

    CERN Document Server

    Mullan, B; Konstantopoulos, I S; Bastian, N; Chandar, R; Durrell, P R; Elmegreen, D; English, J; Gallagher, S C; Gronwall, C; Hibbard, J E; Hunsberger, S; Johnson, K E; Kepley, A; Knierman, K; Koribalski, B; Lee, K H; Maybhate, A; Palma, C; Vacca, W D

    2009-01-01

    We have used V- and I- band images from the Hubble Space Telescope (HST) to identify compact stellar clusters within the tidal tails of twelve different interacting galaxies. The seventeen tails within our sample span a physical parameter space of HI/stellar masses, tail pressure and density through their diversity of tail lengths, optical brightnesses, mass ratios, HI column densities, stage on the Toomre sequence, and tail kinematics. Our preliminary findings in this study indicate that star cluster demographics of the tidal tail environment are compatible with the current understanding of star cluster formation in quiescent systems, possibly only needing changes in certain parameters or normalization of the Schechter cluster initial mass function (CIMF) to replicate what we observe in color-magnitude diagrams and a brightest absolute magnitude -- log N plot.

  12. Tail regeneration affects the digestive performance of a Mediterranean lizard

    Science.gov (United States)

    Sagonas, Kostas; Karambotsi, Niki; Bletsa, Aristoula; Reppa, Aikaterini; Pafilis, Panayiotis; Valakos, Efstratios D.

    2017-04-01

    In caudal autotomy, lizards shed their tail to escape from an attacking predator. Since the tail serves multiple functions, caudal regeneration is of pivotal importance. However, it is a demanding procedure that requires substantial energy and nutrients. Therefore, lizards have to increase energy income to fuel the extraordinary requirements of the regenerating tail. We presumed that autotomized lizards would adjust their digestion to acquire this additional energy. To clarify the effects of tail regeneration on digestion, we compared the digestive performance before autotomy, during regeneration, and after its completion. Tail regeneration indeed increased gut passage time but did not affect digestive performance in a uniform pattern: though protein income was maximized, lipid and sugar acquisition remained stable. This divergence in proteins may be attributed to their particular role in tail reconstruction, as they are the main building blocks for tissue formation.

  13. On the importance of tail ratios for psychological science.

    Science.gov (United States)

    Voracek, Martin; Mohr, Elisabeth; Hagmann, Michael

    2013-06-01

    Even small group-mean differences (whether combined with variance differences or not) or variance differences alone (absent mean differences) can generate marked and sometimes surprising imbalances in the representation of the respective groups compared in the distributional tail regions. Such imbalances in group representation, quantified as tail ratios, have general importance in the context of any threshold, susceptibility, diathesis-stress, selection, or similar models (including the study of sex differences), as widely conceptualized and applied in the psychological, social, medical, and biological sciences. However, commonly used effect-size measures, such as Cohen's d, largely exploit data information around the center of distributions, rather than from the tails, thereby missing potentially important patterns found in the tail regions. This account reviews the background and history of tail ratios, emphasizes their importance for psychological research, proposes a consensus approach for defining and interpreting them, introduces a tail-ratio calculator, and outlines future research agenda.

  14. Carbonic anhydrase inhibitors developed through 'click tailing'.

    Science.gov (United States)

    Lopez, Marie; Salmon, Adam J; Supuran, Claudiu T; Poulsen, Sally-Ann

    2010-01-01

    In recent years there has been renewed activity in the literature concerning the 1,3-dipolar cycloaddition reaction (1,3-DCR) of organic azides (R-N₃) with alkynes (R'-C≡CH) to form 1,2,3-triazoles, i.e. the Huisgen synthesis. The use of catalytic Cu(I) leads to a dramatic rate enhancement (up to 10(7)-fold) and exclusive synthesis of the 1,4-disubstituted 1,2,3-triazole product. The reaction, now referred to as the copper-catalyzed azide-alkyne cycloaddition (CuAAC), meets the stringent criteria of a click-reaction in that it is modular, wide in scope, high yielding, has no byproducts, operates in water at ambient temperature, product purification is simple and the starting materials are readily available. The 1,3-DCR reaction has rapidly become the premier click chemistry reaction with applications spanning modern chemistry disciplines, including medicinal chemistry. Recently the 'tail' approach initiative for the development of carbonic anhydrase inhibitors (CAIs) has been combined with the synthetic versatility of click chemistry. This has proven a powerful combination leading to the synthesis of CAIs with useful biopharmaceutical properties and activities. This review will discuss complementary and contrasting applications that have utilized 'click tailing' for the development of CAIs. Applications encompass i) medicinal chemistry and drug discovery; ii) radiopharmaceutical development of positron emission topography (PET) chemical probes; and iii) in situ click chemistry.

  15. Sulfur biogeochemistry of oil sands composite tailings

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Lesley; Stephenson, Kate [Earth Sciences, McMaster University (Canada)], email: warrenl@mcmaster.ca; Penner, Tara [Syncrude Environmental Research (Canada)

    2011-07-01

    This paper discusses the sulfur biogeochemistry of oil sands composite tailings (CT). The Government of Alberta is accelerating reclamation activities on composite tailings. As a CT pilot reclamation operation, Syncrude is currently constructing the first freshwater fen. Minor unpredicted incidents with H2S gas released from the dewatering process associated with these reclamations have been reported. The objective of this study is to ascertain the connection between microbial activity and H2S generation within CT and to assess the sulfur biogeochemistry of untreated and treated (fen) CT over seasonal and annual timescales. The microbial geochemical interactions taking place are shown using a flow chart. CT is composed of gypsum, sand, clay and organics like naphthenic acids and bitumen. Sulfur and Fe cycling in mining systems and their microbial activities are presented. The chemistry and the processes involved within CT are also given along with the results. It can be said that the diverse Fe and S metabolizing microorganisms confirm the ecology involved in H2S dynamics.

  16. The big head and the long tail

    DEFF Research Database (Denmark)

    Helles, Rasmus

    2013-01-01

    This paper discusses how the advent of big data challenges established theories in Internet studies to redevelop existing explanatory strategies in order to incorporate the possibilities offered by this new empirical resource. The article suggests that established analytical procedures and theore......This paper discusses how the advent of big data challenges established theories in Internet studies to redevelop existing explanatory strategies in order to incorporate the possibilities offered by this new empirical resource. The article suggests that established analytical procedures...... and theoretical frameworks used in Internet studies can be fruitfully employed to explain high–level structural phenomena that are only observable through the use of big data. The present article exemplifies this by offering a detailed analysis of how genre analysis of Web sites may be used to shed light...... on the generative mechanism behind the long–tail distribution of Web site use. The analysis shows that the long tail should be seen as a tiered version of popular top sites, and argues that downsizing of large–scale datasets in combination with qualitative and/or small–scale quantitative procedures may provide...

  17. A red-tailed hawk at KSC

    Science.gov (United States)

    2000-01-01

    At KSC, a red-tailed hawk waits on top of a utility pole for the slightest movement in the grass below. It feeds mostly on small rodents. Ranging in height from 18 inches to 25 inches, the species has a stocky build with a whitish breast and rust-colored tail. It has a high-pitched descending scream with a hoarse quality. The hawk inhabits mainly deciduous forest and adjacent open country from Alaska and Nova Scotia south to Panama. KSC shares a boundary with the Merritt Island National Wildlife Refuge, which encompasses 92,000 acres that are a habitat for more than 331 species of birds, 31 mammals, 117 fishes, and 65 amphibians and reptiles. The marshes and open water of the refuge provide wintering areas for 23 species of migratory waterfowl, as well as a year-round home for great blue herons, great egrets, wood storks, cormorants, brown pelicans and other species of marsh and shore birds, as well as a variety of insects.

  18. Environmental impact analysis of mine tailing reservoir

    Science.gov (United States)

    Gong, J. Z.

    2016-08-01

    Under certain conditions landscape topography which utilizes mine tailing reservoir construction using is likely to increase lateral recharge source regions, resulting in dramatic changes to the local hydrological dynamic field and recharge of downstream areas initiated by runoff, excretion state, elevated groundwater depth, shallow groundwater, rainfall direct communication, and thinning of the vadose zone. Corrosive leaching of topsoil over many years of exposure to chemical fertilizers and pesticides may result in their dissolution into the groundwater system, which may lead to excessive amounts of many harmful chemicals, therby affecting the physical and mental health of human residents and increase environmental vulnerability and risk associated with the water and soil. According to field survey data from Yujiakan, Qian'an City, and Hebei provinces, this paper analyzes the hydrogeological environmental mechanisms of areas adjacent to mine tailing reservoirs and establishes a conceptual model of the local groundwater system and the concentration-response function between NO3 - content in groundwater and the incidence of cancer in local residents.

  19. Measurements of uranium mill tailings consolidation characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Fayer, M J

    1985-02-01

    A series of experiments were conducted on uranium mill tailings from the tailings pile in Grand Junction, Colorado, to determine their consolidation characteristics. Three materials (sand, sand/slimes mix, slimes) were loaded under saturated conditions to determine their saturated consolidated behavior. During a separate experiment, samples of the slimes material were kept under a constant load while the pore pressure was increased to determine the partially saturated consolidation behavior. Results of the saturated tests compared well with published data. Sand consolidated the least, while slimes consolidated the most. As each material consolidated, the measured hydraulic conductivity decreased in a linear fashion with respect to the void ratio. Partially saturated experiments with the slimes indicated that there was little consolidation as the pore pressure was increased progressively above 7 kPa. The small amount of consolidation that did occur was only a fraction of the amount of saturated consolidation. Preliminary measurements between pore pressures of 0 and 7 kPa indicated that measurable consolidation could occur in this range of pore pressure, but only if there was no load. 13 references, 13 figures.

  20. Non-equilibrium and band tailing in organic conductors

    Indian Academy of Sciences (India)

    A T Oza; P C Vinodkumar; R G Patel

    2003-03-01

    The concept of band tailing with focal point and width of the tail from IR absorption spectra of different organic conductors is found valid even for thermal and elastic changes. The experimental situations like change of solvents, method of preparation, applied pressure and pressure cycle apart from compositions is analyzed within the framework of tailing of states. Non-equilibrium due to coupling between applied energy and free electrons can be responsible for the exponential relaxation from non-equilibrium to equilibrium.

  1. Tails assumptions and posterior concentration rates for mixtures of Gaussians

    OpenAIRE

    Naulet, Zacharie; Rousseau, Judith

    2016-01-01

    Nowadays in density estimation, posterior rates of convergence for location and location-scale mixtures of Gaussians are only known under light-tail assumptions; with better rates achieved by location mixtures. It is conjectured, but not proved, that the situation should be reversed under heavy tails assumptions. The conjecture is based on the feeling that there is no need to achieve a good order of approximation in regions with few data (say, in the tails), favoring location-scale mixtures w...

  2. Pre-Mrna Introns as a Model for Cryptographic Algorithm:. Theory and Experiments

    Science.gov (United States)

    Regoli, Massimo

    2010-01-01

    The RNA-Crypto System (shortly RCS) is a symmetric key algorithm to cipher data. The idea for this new algorithm starts from the observation of nature. In particular from the observation of RNA behavior and some of its properties. In particular the RNA sequences have some sections called Introns. Introns, derived from the term "intragenic regions", are non-coding sections of precursor mRNA (pre-mRNA) or other RNAs, that are removed (spliced out of the RNA) before the mature RNA is formed. Once the introns have been spliced out of a pre-mRNA, the resulting mRNA sequence is ready to be translated into a protein. The corresponding parts of a gene are known as introns as well. The nature and the role of Introns in the pre-mRNA is not clear and it is under ponderous researches by Biologists but, in our case, we will use the presence of Introns in the RNA-Crypto System output as a strong method to add chaotic non coding information and an unnecessary behaviour in the access to the secret key to code the messages. In the RNA-Crypto System algorithm the introns are sections of the ciphered message with non-coding information as well as in the precursor mRNA.

  3. Recovery of Iron from Copper Tailings by Direct Reduction

    Science.gov (United States)

    Gu, Jing; Xia, De-Hong; Gu, Jing; Liu, Kai-Qi; Zhang, Feng; Wang, Shou-Zeng; Qi, Zhao-Dong; Ao, Wen-Qing

    2016-05-01

    Direct reduction of copper tailings were performed to recover iron efficiently by carbon-containing pellets, and the metallization rate was gained by chemical analysis method. The results showed that the metallization rate of copper tailings was up to 85.32% and the best reduction parameters are also found. Content of precious metals, such as, gold, silver in copper tailings can be enriched by 1.8~1.9 times through removing iron. The apparent activation energy of direct reduction of iron oxide in copper tailings is calculated to be 125.4 kJ/mol and the restrictive factor of reduction process is solid diffusion.

  4. Reclamation of copper mine tailings using sewage sludge

    OpenAIRE

    Stjernman Forsberg, Lovisa

    2008-01-01

    Tailings are the fine-grained fraction of waste produced during mining operations. This work was carried out on tailings from the Aitik copper mine in northern Sweden. Establishment of vegetation on the Aitik mine tailings deposit is planned to take place at closure of the mine, using sewage sludge as fertiliser. However, the tailings contain traces of metal sulphides, e.g. pyrite, FeS2, and chalcopyrite, CuFeS2. When the sulphides are oxidised, they start to weather and release metals and st...

  5. Ecological restoration alters microbial communities in mine tailings profiles

    Science.gov (United States)

    Li, Yang; Jia, Zhongjun; Sun, Qingye; Zhan, Jing; Yang, Yang; Wang, Dan

    2016-04-01

    Ecological restoration of mine tailings have impact on soil physiochemical properties and microbial communities. The surface soil has been a primary concern in the past decades, however it remains poorly understood about the adaptive response of microbial communities along the profile during ecological restoration of the tailings. In this study, microbial communities along a 60-cm profile were investigated in a mine tailing pond during ecological restoration of the bare waste tailings (BW) with two vegetated soils of Imperata cylindrica (IC) and Chrysopogon zizanioides (CZ) plants. Revegetation of both IC and CZ could retard soil degradation of mine tailing by stimulation of soil pH at 0-30 cm soils and altered the bacterial communities at 0-20 cm depths of the mine tailings. Significant differences existed in the relative abundance of the phyla Alphaproteobacteria, Deltaproteobacteria, Acidobacteria, Firmicutes and Nitrospira. Slight difference of bacterial communities were found at 30-60 cm depths of mine tailings. Abundance and activity analysis of nifH genes also explained the elevated soil nitrogen contents at the surface 0-20 cm of the vegetated soils. These results suggest that microbial succession occurred primarily at surface tailings and vegetation of pioneering plants might have promoted ecological restoration of mine tailings.

  6. Evolution of tail fork depth in genus Hirundo.

    Science.gov (United States)

    Hasegawa, Masaru; Arai, Emi; Kutsukake, Nobuyuki

    2016-02-01

    A classic example of a sexually selected trait, the deep fork tail of the barn swallow Hirundo rustica is now claimed to have evolved and be maintained mainly via aerodynamic advantage rather than sexually selected advantage. However, this aerodynamic advantage hypothesis does not clarify which flight habits select for/against deep fork tails, causing diversity of tail fork depth in hirundines. Here, by focusing on the genus Hirundo, we investigated whether the large variation in tail fork depth could be explained by the differential flight habits. Using a phylogenetic comparative approach, we found that migrant species had deeper fork tails, but less colorful plumage, than the other species, indicating that migration favors a specific trait, deep fork tails. At the same time, tail fork depth but not plumage coloration decreased with increasing bill size - a proxy of prey size, suggesting that foraging on larger prey items favors shallower fork tails. Variation of tail fork depth in the genus Hirundo may be explained by differential flight habits, even without assuming sexual selection.

  7. Estimating impact forces of tail club strikes by ankylosaurid dinosaurs.

    Directory of Open Access Journals (Sweden)

    Victoria Megan Arbour

    Full Text Available BACKGROUND: It has been assumed that the unusual tail club of ankylosaurid dinosaurs was used actively as a weapon, but the biological feasibility of this behaviour has not been examined in detail. Ankylosaurid tail clubs are composed of interlocking vertebrae, which form the handle, and large terminal osteoderms, which form the knob. METHODOLOGY/PRINCIPAL FINDINGS: Computed tomographic (CT scans of several ankylosaurid tail clubs referred to Dyoplosaurus and Euoplocephalus, combined with measurements of free caudal vertebrae, provide information used to estimate the impact force of tail clubs of various sizes. Ankylosaurid tails are modeled as a series of segments for which mass, muscle cross-sectional area, torque, and angular acceleration are calculated. Free caudal vertebrae segments had limited vertical flexibility, but the tail could have swung through approximately 100 degrees laterally. Muscle scars on the pelvis record the presence of a large M. longissimus caudae, and ossified tendons alongside the handle represent M. spinalis. CT scans showed that knob osteoderms were predominantly cancellous, which would have lowered the rotational inertia of the tail club and made it easier to wield as a weapon. CONCLUSIONS/SIGNIFICANCE: Large knobs could generate sufficient force to break bone during impacts, but average and small knobs could not. Tail swinging behaviour is feasible in ankylosaurids, but it remains unknown whether the tail was used for interspecific defense, intraspecific combat, or both.

  8. A survey of straw use and tail biting in Swedish pig farms rearing undocked pigs

    OpenAIRE

    Wallgren, Torun; Westin, Rebecka; Gunnarsson, Stefan

    2016-01-01

    Background Tail biting is a common problem in intensive pig farming, affecting both welfare and production. Although routine tail docking is banned within the EU, it remains a common practice to prevent tail biting. Straw as environmental enrichment has been proposed as an alternative to tail docking, but its effectiveness against tail biting and function in manure handling systems have to be considered. The aim of the study was to survey how pigs with intact tails are raised and how tail bit...

  9. Proceedings of the 15. annual British Columbia MEND ML/ARD workshop : the management of tailings and tailings impoundments

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-02-15

    This Mine Environment Neutral Drainage (MEND) workshop was held to promote the exchange of information and ideas on environmental protection and reclamation associated with mining. The workshop covered a broad spectrum of reclamation issues and the key environmental challenges facing the mining industry, such as acid mine drainage (AMD) control, and metal leaching and acid rock drainage (ML/ARD). The theme for the 2008 workshop was the management of tailings and tailings impoundments. Topics of discussion included hydrogeology and geochemistry; tailings disposal; mitigation; closure plans; and postclosure performance. The emphasis was on full-scale case studies, practical constraints and sustaining successful disposal strategies and remediation. The session on tailings management reviewed overarching policies and practices; methods of subaerial tailings disposal and case studies of tailings management; and detailed investigations of geochemical properties and processes. The conference featured 22 presentations, of which 4 have been catalogued separately for inclusion in this database. refs., tabs., figs.

  10. Effects of Tail Clipping on Larval Performance and Tail Regeneration Rates in the Near Eastern Fire Salamander, Salamandra infraimmaculata.

    Directory of Open Access Journals (Sweden)

    Ori Segev

    Full Text Available Tail-tip clipping is a common technique for collecting tissue samples from amphibian larvae and adults. Surprisingly, studies of this invasive sampling procedure or of natural tail clipping--i.e., bites inflicted by predators including conspecifics--on the performance and fitness of aquatic larval stages of urodeles are scarce. We conducted two studies in which we assessed the effects of posterior tail clipping (~30 percent of tail on Near Eastern fire salamander (Salamandra infraimmaculata larvae. In a laboratory study, we checked regeneration rates of posterior tail-tip clipping at different ages. Regeneration rates were hump-shaped, peaking at the age of ~30 days and then decreasing. This variation in tail regeneration rates suggests tradeoffs in resource allocation between regeneration and somatic growth during early and advanced development. In an outdoor artificial pond experiment, under constant larval densities, we assessed how tail clipping of newborn larvae affects survival to, time to, and size at metamorphosis. Repeated measures ANOVA on mean larval survival per pond revealed no effect of tail clipping. Tail clipping had correspondingly no effect on larval growth and development expressed in size (mass and snout-vent length at, and time to, metamorphosis. We conclude that despite the given variation in tail regeneration rates throughout larval ontogeny, clipping of 30% percent of the posterior tail area seems to have no adverse effects on larval fitness and survival. We suggest that future use of this imperative tool for the study of amphibian should take into account larval developmental stage during the time of application and not just the relative size of the clipped tail sample.

  11. Effects of Tail Clipping on Larval Performance and Tail Regeneration Rates in the Near Eastern Fire Salamander, Salamandra infraimmaculata.

    Science.gov (United States)

    Segev, Ori; Polevikove, Antonina; Blank, Lior; Goedbloed, Daniel; Küpfer, Eliane; Gershberg, Anna; Koplovich, Avi; Blaustein, Leon

    2015-01-01

    Tail-tip clipping is a common technique for collecting tissue samples from amphibian larvae and adults. Surprisingly, studies of this invasive sampling procedure or of natural tail clipping--i.e., bites inflicted by predators including conspecifics--on the performance and fitness of aquatic larval stages of urodeles are scarce. We conducted two studies in which we assessed the effects of posterior tail clipping (~30 percent of tail) on Near Eastern fire salamander (Salamandra infraimmaculata) larvae. In a laboratory study, we checked regeneration rates of posterior tail-tip clipping at different ages. Regeneration rates were hump-shaped, peaking at the age of ~30 days and then decreasing. This variation in tail regeneration rates suggests tradeoffs in resource allocation between regeneration and somatic growth during early and advanced development. In an outdoor artificial pond experiment, under constant larval densities, we assessed how tail clipping of newborn larvae affects survival to, time to, and size at metamorphosis. Repeated measures ANOVA on mean larval survival per pond revealed no effect of tail clipping. Tail clipping had correspondingly no effect on larval growth and development expressed in size (mass and snout-vent length) at, and time to, metamorphosis. We conclude that despite the given variation in tail regeneration rates throughout larval ontogeny, clipping of 30% percent of the posterior tail area seems to have no adverse effects on larval fitness and survival. We suggest that future use of this imperative tool for the study of amphibian should take into account larval developmental stage during the time of application and not just the relative size of the clipped tail sample.

  12. Assessment of water removal from oil sands tailings by evaporation and under-drainage, and the impact on tailings consolidation

    Energy Technology Data Exchange (ETDEWEB)

    Junqueira, Fernando F.; Sanin, Maria Victoria [Golder Associates Ltd (Canada); Sedgwick, Andrea [Total EandP Canada (Canada); Blum, Jim [JG Blum Consulting Ltd (Canada)

    2011-07-01

    Tailings, left-over material produced during the extraction process that separates bitumen from oil sand, are challenging the oil sands industry. These tailings require large surface areas and contain mature fine tailings, made up of fine clay particles suspended in water, which do not settle within a reasonable timeframe. Consequently, maximizing water removal from oil sands tailings is required to accelerate tailings consolidation. The study described in this paper was developed to measure the water loss from oil sands tailings associated with evaporation and under-drainage, using laboratory drying column tests, and to evaluate the impact of water loss on the process of tailings consolidation and the gain in shear strength for different lift thicknesses. Water removal from the tailings through evaporation occurred at a nearly constant rate, while the rate of under-drainage progressively reduced with time. Additionally, it was found that thinner lifts would have better performance in terms of tailings consolidation and gain in shear strength than thick lifts.

  13. A proactive approach to sustainable management of mine tailings

    Science.gov (United States)

    Edraki, Mansour; Baumgartl, Thomas

    2015-04-01

    The reactive strategies to manage mine tailings i.e. containment of slurries of tailings in tailings storage facilities (TSF's) and remediation of tailings solids or tailings seepage water after the decommissioning of those facilities, can be technically inefficient to eliminate environmental risks (e.g. prevent dispersion of contaminants and catastrophic dam wall failures), pose a long term economic burden for companies, governments and society after mine closure, and often fail to meet community expectations. Most preventive environmental management practices promote proactive integrated approaches to waste management whereby the source of environmental issues are identified to help make a more informed decisions. They often use life cycle assessment to find the "hot spots" of environmental burdens. This kind of approach is often based on generic data and has rarely been used for tailings. Besides, life cycle assessments are less useful for designing operations or simulating changes in the process and consequent environmental outcomes. It is evident that an integrated approach for tailings research linked to better processing options is needed. A literature review revealed that there are only few examples of integrated approaches. The aim of this project is to develop new tailings management models by streamlining orebody characterization, process optimization and rehabilitation. The approach is based on continuous fingerprinting of geochemical processes from orebody to tailings storage facility, and benchmark the success of such proactive initiatives by evidence of no impacts and no future projected impacts on receiving environments. We present an approach for developing such a framework and preliminary results from a case study where combined grinding and flotation models developed using geometallurgical data from the orebody were constructed to predict the properties of tailings produced under various processing scenarios. The modelling scenarios based on the

  14. Radiological impact of uranium tailings and alternatives for their management

    Energy Technology Data Exchange (ETDEWEB)

    Momeni, M. H.; Kisieleski, W. E.; Tyler, S.; Zielen, A.; Yuan, Y.; Roberts, C. J.

    1979-01-01

    Uncontrolled tailings piles are mobile sources of fugitive dust that may produce a practically uncleanable adjacent environment. A practical procedure for managing solid tailings is addition of surface moisture, mechanical and gravitational separation of slimes, and storage of slimes below solution tailings. Presently practical alternatives for tailings management are variations of two basic methods - surface below-ground disposal. Isolation of tailings by natural materials such as clay lenses and combinations of overburden, top soil, vegetation and rip-rap may provide both minimization of exposure and stability. Experimental measurement of radon flux over two inactive tailings, acid and carbonate leached tailings resulted in average specific flux values of phi infinity approx. = 0.64 and phi infinity approx. = 0.30 (pCi Rn-222/m/sup 2/ sec) / (pCi Ra-226/g), respectively. The average diffusion coefficient for these tailings were, respectively, 2.4 x 10/sup -3/ and 5.7 x 10/sup -4/ cm/sup 2//sec. Tailings covered with native soil of clay-silt-sand mixture to a depth of 225 cm resulted in attenuation of flux with diffusion coefficients of 3.69 x 10/sup -3/ and 3.60 x 10/sup -3/ cm/sup 2//sec for ACID and ALKO sites, respectively. By means of the UDAD code dose commitments were estimated for inhalation of particulates and radon and for external exposure under three degrees of surface moisture on the tailings. Based on these analyses and assumption that the dose contribution from ingestion pathway is comparable in magnitude to that of inhalation, both compliance with the 25 mrem/year limit and reduction of flux to background level is feasible. Stability of alternative decommissioned tailings over the predictable future is discussed.

  15. Rheologicai properties of tailing paste slurry

    Institute of Scientific and Technical Information of China (English)

    王新民; 李建雄; 肖智政; 肖卫国

    2004-01-01

    The initial shear stress (τ) and plastic cohesion (η) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship among the consumption of different fill materials were obtained through the experiment and research on these parameters.They can be used to predict the scope of the values of τ and η in production for a given ratio, which can reduce the conveying resistance of fill slurry along the pipelines and avoid the blockage of the pipelines. It is found that the rheological model of the total tailing slurry belongs to the Bingham type, which has a feature of strong internal structure and large initial shear stress. The calculation formula for the resistance loss of pipelines conforms nicely to the field test and the actual production in Jinchuan Nickel Mine.

  16. Testing for tail behavior using extreme spacings

    CERN Document Server

    Rojo, J

    2010-01-01

    Methodologies to test hypotheses about the tail-heaviness of an underlying distribution are introduced based on results of Rojo (1996) using the limiting behavior of the extreme spacings. The tests are consistent and have point-wise robust levels in the sense of Lehmann (2005) and Lehmann and Loh (1990). Simulation results based on these new methodologies indicate that the tests exhibit good control of the probability of Type I error and have good power properties for finite sample sizes. The tests are compared with a test proposed by Bryson (1974) and it is seen that, although Bryson's test is competitive with the tests proposed here, Bryson's test does not have point-wise robust levels. The operating characteristics of the tests are also explored when the data is blocked. It turns out that the power increases substantially by blocking. The methodology is illustrated by analyzing various data sets.

  17. The Radiative Tail of Realistic Gravitational Collapse

    CERN Document Server

    Hod, S

    2000-01-01

    An astrophysically realistic model of wave dynamics in black-hole spacetimes must involve a {\\it non}-spherical background geometry with {\\it angular momentum}. We consider the evolution of {\\it gravitational} (and electromagnetic) perturbations in {\\it rotating} Kerr spacetimes. We show that a rotating Kerr black hole becomes ``bald'' {\\it slower} than the corresponding spherically-symmetric Schwarzschild black hole. Moreover, our results {\\it turn over} the traditional belief (which has been widely accepted during the last three decades) that the late-time tail of gravitational collapse is universal. In particular, we show that different fields have {\\it different} decaying rates. Our results are also of importance both to the study of the no-hair conjecture and the mass-inflation scenario (stability of Cauchy horizons).

  18. Right tail increasing dependence between scores

    Science.gov (United States)

    Fernández, M.; García, Jesús E.; González-López, V. A.; Romano, N.

    2017-07-01

    In this paper we investigate the behavior of the conditional probability Prob(U > u|V > v) of two records coming from students of an undergraduate course, where U is the score of calculus I, scaled in [0, 1] and V is the score of physics scaled in [0, 1], the physics subject is part of the admission test of the university. For purposes of comparison, we consider two different undergraduate courses, electrical engineering and mechanical engineering, during nine years, from 2003 to 2011. Through a Bayesian perspective we estimate Prob(U > u|V > v) year by year and course by course. We conclude that U is right tail increasing in V, in both courses and for all the years. Moreover, over these nine years, we observe different ranges of variability for the estimated probabilities of electrical engineering when compared to the estimated probabilities of mechanical engineering.

  19. Correlations in quantum plasmas. II. Algebraic tails

    Science.gov (United States)

    Cornu, F.

    1996-05-01

    For a system of point charges that interact through the three-dimensional electrostatic Coulomb potential (without any regularization) and obey the laws of nonrelativistic quantum mechanics with Bose or Fermi statistics, the static correlations between particles are shown to have a 1/r6 tail, at least at distances that are large with respect to the length of exponential screening. After a review of previous work, a term-by-term diagrammatic proof is given by using the formalism of paper I, where the quantum particle-particle correlations are expressed in terms of classical-loop distribution functions. The integrable graphs of the resummed Mayer-like diagrammatics for the loop distributions contain bonds between loops that decay either exponentially or algebraically, with a 1/r3 leading term analogous to a dipole-dipole interaction. This reflects the fact that the charge-charge or multipole-charge interactions between clusters of particles surrounded by their polarization clouds are exponentially screened, as at a classical level, whereas the multipole-multipole interactions are only partially screened. The correlation between loops decays as 1/r3, but the spherical symmetry of the quantum fluctuations makes this power law fall to 1/r5, and the harmonicity of the Coulomb potential eventually enforces the correlations between quantum particles to decay only as 1/r6. The coefficient of the 1/r6 tail at low density is planned to be given in a subsequent paper. Moreover, because of Coulomb screening, the induced charge density, which describes the response to an external infinitesimal charge, is shown to fall off as 1/r8, while the charge-charge correlation in the medium decreases as 1/r10. However, in spite of the departure of the quantum microscopic correlations from the classical exponential clustering, the total induced charge is still essentially determined by the exponentially screened charge-charge interactions, as in classical macroscopic electrostatics.

  20. A Glimpse of the genomic diversity of haloarchaeal tailed viruses

    Directory of Open Access Journals (Sweden)

    Ana eSencilo

    2014-03-01

    Full Text Available Tailed viruses are the most common isolates infecting prokaryotic hosts residing hypersaline environments. Archaeal tailed viruses represent only a small portion of all characterized tailed viruses of prokaryotes. But even this small dataset revealed that archaeal tailed viruses have many similarities to their counterparts infecting bacteria, the bacteriophages. Shared functional homologues and similar genome organizations suggested that all microbial tailed viruses have common virion architectural and assembly principles. Recent structural studies have provided evidence justifying this thereby grouping archaeal and bacterial tailed viruses into a single lineage. Currently there are 17 haloarchaeal tailed viruses with entirely sequenced genomes. Nine viruses have at least one close relative among the 17 viruses and, according to the similarities, can be divided into three groups. Two other viruses share some homologues and therefore are distantly related, whereas the rest of the viruses are rather divergent (or singletons. Comparative genomics analysis of these viruses offers a glimpse into the genetic diversity and structure of haloarchaeal tailed virus communities.

  1. Structural Conservation of the Myoviridae Phage Tail Sheath Protein Fold

    Energy Technology Data Exchange (ETDEWEB)

    Aksyuk, Anastasia A.; Kurochkina, Lidia P.; Fokine, Andrei; Forouhar, Farhad; Mesyanzhinov, Vadim V.; Tong, Liang; Rossmann, Michael G. (SOIBC); (Purdue); (Columbia)

    2012-02-21

    Bacteriophage phiKZ is a giant phage that infects Pseudomonas aeruginosa, a human pathogen. The phiKZ virion consists of a 1450 {angstrom} diameter icosahedral head and a 2000 {angstrom}-long contractile tail. The structure of the whole virus was previously reported, showing that its tail organization in the extended state is similar to the well-studied Myovirus bacteriophage T4 tail. The crystal structure of a tail sheath protein fragment of phiKZ was determined to 2.4 {angstrom} resolution. Furthermore, crystal structures of two prophage tail sheath proteins were determined to 1.9 and 3.3 {angstrom} resolution. Despite low sequence identity between these proteins, all of these structures have a similar fold. The crystal structure of the phiKZ tail sheath protein has been fitted into cryo-electron-microscopy reconstructions of the extended tail sheath and of a polysheath. The structural rearrangement of the phiKZ tail sheath contraction was found to be similar to that of phage T4.

  2. Thresher sharks use tail-slaps as a hunting strategy.

    Science.gov (United States)

    Oliver, Simon P; Turner, John R; Gann, Klemens; Silvosa, Medel; D'Urban Jackson, Tim

    2013-01-01

    The hunting strategies of pelagic thresher sharks (Alopias pelagicus) were investigated at Pescador Island in the Philippines. It has long been suspected that thresher sharks hunt with their scythe-like tails but the kinematics associated with the behaviour in the wild are poorly understood. From 61 observations recorded by handheld underwater video camera between June and October 2010, 25 thresher shark shunting events were analysed. Thresher sharks employed tail-slaps to debilitate sardines at all times of day. Hunting events comprised preparation, strike, wind-down recovery and prey item collection phases, which occurred sequentially. Preparation phases were significantly longer than the others, presumably to enable a shark to windup a tail-slap. Tail-slaps were initiated by an adduction of the pectoral fins, a manoeuvre that changed a thresher shark's pitch promoting its posterior region to lift rapidly, and stall its approach. Tail-slaps occurred with such force that they may have caused dissolved gas to diffuse out of the water column forming bubbles. Thresher sharks were able to consume more than one sardine at a time, suggesting that tail-slapping is an effective foraging strategy for hunting schooling prey. Pelagic thresher sharks appear to pursue sardines opportunistically by day and night, which may make them vulnerable to fisheries. Alopiids possess specialist pectoral and caudal fins that are likely to have evolved, at least in part, for tail-slapping. The evidence is now clear; thresher sharks really do hunt with their tails.

  3. Shrinkage and swelling properties of flocculated mature fine tailings

    NARCIS (Netherlands)

    Yao, Y.; Van Tol, A.F.; Van Paassen, L.A.; Vardon, P.J.

    2014-01-01

    In the atmospheric fines drying technique, mature fine tailings (MFT) are treated with polymers and deposited in thin layers on a sloped surface for sub-aerial drying. During the whole drying period, the tailings deposits can experience rewetting during periods of rainy weather or as result of the

  4. Efficient simulation of tail probabilities of sums of correlated lognormals

    DEFF Research Database (Denmark)

    Asmussen, Søren; Blanchet, José; Juneja, Sandeep;

    We consider the problem of efficient estimation of tail probabilities of sums of correlated lognormals via simulation. This problem is motivated by the tail analysis of portfolios of assets driven by correlated Black-Scholes models. We propose two estimators that can be rigorously shown to be eff...

  5. Moth tails divert bat attack: evolution of acoustic deflection.

    Science.gov (United States)

    Barber, Jesse R; Leavell, Brian C; Keener, Adam L; Breinholt, Jesse W; Chadwell, Brad A; McClure, Christopher J W; Hill, Geena M; Kawahara, Akito Y

    2015-03-03

    Adaptations to divert the attacks of visually guided predators have evolved repeatedly in animals. Using high-speed infrared videography, we show that luna moths (Actias luna) generate an acoustic diversion with spinning hindwing tails to deflect echolocating bat attacks away from their body and toward these nonessential appendages. We pit luna moths against big brown bats (Eptesicus fuscus) and demonstrate a survival advantage of ∼ 47% for moths with tails versus those that had their tails removed. The benefit of hindwing tails is equivalent to the advantage conferred to moths by bat-detecting ears. Moth tails lured bat attacks to these wing regions during 55% of interactions between bats and intact luna moths. We analyzed flight kinematics of moths with and without hindwing tails and suggest that tails have a minimal role in flight performance. Using a robust phylogeny, we find that long spatulate tails have independently evolved four times in saturniid moths, further supporting the selective advantage of this anti-bat strategy. Diversionary tactics are perhaps more common than appreciated in predator-prey interactions. Our finding suggests that focusing on the sensory ecologies of key predators will reveal such countermeasures in prey.

  6. Characterisation of gold tailings dams of the Witwatersrand Basin ...

    African Journals Online (AJOL)

    2006-10-04

    Oct 4, 2006 ... gen in the Witwatersrand tailings dams is controlled by secondary porosity (i.e. cracks caused .... different properties and characteristics of tailings material. .... Z o n e. O. Z. T. Z. U. Z 1. U. Z 2. O. Z 1. O. Z 2. T. Z. U. Z. O. Z 1. O.

  7. Lifshitz Tails for the Interband Light Absorption Coefficient

    Indian Academy of Sciences (India)

    W Kirsch; M Krishna

    2010-09-01

    In this paper we consider the interband light absorption coefficient (ILAC) for various models. We show that at the lower and upper edges of the spectrum the Lifshitz tails behaviour of the density of states implies similar behaviour for the ILAC at appropriate energies. The Lifshitz tails property is also exhibited at some points corresponding to the internal band edges of the spectrum.

  8. An expeditious synthesis of tailed tren-capped porphyrins.

    Science.gov (United States)

    Even, Pascale; Ruzié, Christian; Ricard, David; Boitrel, Bernard

    2005-09-29

    [structure: see text] A one-pot two-step versatile synthesis of tailed tren-capped porphyrins has been achieved. The two resulting ligands demonstrate that this expeditious method can be applied to various axial bases to obtain highly functionalized macromolecules attractive for heme modeling purposes. Dioxygen binding of the pyridine-tailed iron complex is reported as a direct application.

  9. Tail index and quantile estimation with very high frequency data

    NARCIS (Netherlands)

    J. Daníelsson (Jón); C.G. de Vries (Casper)

    1997-01-01

    textabstractA precise estimation of the tail shape of forex returns is of critical importance for proper risk assessment. We improve upon the efficiency of conventional estimators that rely on a first order expansion of the tail shape, by using the second order expansion. Here we advocate a moments

  10. Tail index and quantile estimation with very high frequency data

    NARCIS (Netherlands)

    J. Daníelsson (Jón); C.G. de Vries (Casper)

    1997-01-01

    textabstractA precise estimation of the tail shape of forex returns is of critical importance for proper risk assessment. We improve upon the efficiency of conventional estimators that rely on a first order expansion of the tail shape, by using the second order expansion. Here we advocate a moments

  11. 14 CFR 29.547 - Main and tail rotor structure.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Main and tail rotor structure. 29.547 Section 29.547 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Requirements § 29.547 Main and tail rotor structure. (a) A rotor is an assembly of rotating components, which...

  12. Female tail wagging enhances sexual performance in male goats.

    Science.gov (United States)

    Haulenbeek, Andrea M; Katz, Larry S

    2011-08-01

    Preference testing has shown that sexually experienced male goats choose females that are tail wagging, a behavior that may function as both attractivity and proceptivity, over those that are not. We hypothesized that exposure to females expressing high rates of tail wagging would arouse males, increasing sexual performance. Tail wagging rate could be manipulated because we have shown previously that flutamide treatment increases the frequency of tail wagging in estrous goats. Sexually experienced males observed different stimuli for 10 min before a 20 min sexual performance test (SPT). The stimuli were an empty pen (MT), or groups of three females that were all estrous (E), non-estrous (NE), estrous+flutamide (E(F)) or non-estrous+flutamide (NE(F)). During the stimulus observation period, tail wagging was recorded. During SPT, frequencies and latencies of sexual behaviors were recorded. E(F) females displayed the most tail wagging. Viewing E(F) females before SPT increased the number of ejaculations attained by males and decreased the latencies to first and second ejaculation, as well as the inter-ejaculatory interval. Viewing estrous females (E and E(F)) before SPT decreased the latency to first mount, as compared to non-estrous females (NE and NE(F)). We conclude that male goats are sexually aroused by tail wagging. This study and previous work demonstrate that tail wagging functions as both attractivity and proceptivity in goats. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Characteristics of tailings from metal mines in Hunan Province, China

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-guo; ZHANG Hui-zhi; ZENG Guang-ming; HUANG Bao-rong; LI Xin; XU Wei-hua

    2005-01-01

    The tailing soils were from 10 mining areas in Hunan Province. To predict the potential impact of tailings on nearby environments, the characteristics such as the pH value, loss on ignition, cation exchange capacity, and the concentration and speciation of heavy metals in the tailings were investigated. Based on these characteristics, the pollution index and danger index were calculated so as to evaluate the priorities of remediation. The results show that the concentrations of Pb, Cd, Cu and Zn exceed the tolerable levels of the phytotoxicity in the most tailings. The large proportion of heavy metals exists in the form of residual fraction in most tailings, followed by sulfides/organic and Fe/Mn oxide fractions, and a little in the exchangeable and carbonate fraction. The calculated pollution indices for the tailing samples range from 1.41 to 83.42, which indicates that all the tailings contain heavy metals at a level that causes toxicity to the ecosystem. The danger indices for the tailing samples range from 0.06 to 387.00. The highest value of the danger indices is that of Yongzhou sample, reaching 387.00; the lowest one is that of Xikuangshan sample, only 0.06. Considering the results of pollution index and danger index in combination, the priority of remediation is determined to be Yongzhou, Baoshan, Xiangtan and Lengshuijiang.

  14. Thresher sharks use tail-slaps as a hunting strategy.

    Directory of Open Access Journals (Sweden)

    Simon P Oliver

    Full Text Available The hunting strategies of pelagic thresher sharks (Alopias pelagicus were investigated at Pescador Island in the Philippines. It has long been suspected that thresher sharks hunt with their scythe-like tails but the kinematics associated with the behaviour in the wild are poorly understood. From 61 observations recorded by handheld underwater video camera between June and October 2010, 25 thresher shark shunting events were analysed. Thresher sharks employed tail-slaps to debilitate sardines at all times of day. Hunting events comprised preparation, strike, wind-down recovery and prey item collection phases, which occurred sequentially. Preparation phases were significantly longer than the others, presumably to enable a shark to windup a tail-slap. Tail-slaps were initiated by an adduction of the pectoral fins, a manoeuvre that changed a thresher shark's pitch promoting its posterior region to lift rapidly, and stall its approach. Tail-slaps occurred with such force that they may have caused dissolved gas to diffuse out of the water column forming bubbles. Thresher sharks were able to consume more than one sardine at a time, suggesting that tail-slapping is an effective foraging strategy for hunting schooling prey. Pelagic thresher sharks appear to pursue sardines opportunistically by day and night, which may make them vulnerable to fisheries. Alopiids possess specialist pectoral and caudal fins that are likely to have evolved, at least in part, for tail-slapping. The evidence is now clear; thresher sharks really do hunt with their tails.

  15. A Tale of Two Tails: Exploring Stellar Populations in the Tidal Tails of NGC 3256

    CERN Document Server

    Rodruck, Michael; Knierman, Karen; Fedotov, Konstantin; Mullan, Brendan; Gallagher, Sarah; Gallagher, Sarah; Durrell, Patrick; Ciardullo, Robin; Gronwall, Caryl; Charlton, Jane

    2016-01-01

    We have developed an observing program using deep, multiband imaging to probe the chaotic regions of tidal tails in search of an underlying stellar population, using NGC 3256's 400 Myr twin tidal tails as a case study. These tails have different colours of $u - g = 1.05 \\pm 0.07$ and $r - i = 0.13 \\pm 0.07$ for NGC 3256W, and $u - g = 1.26 \\pm 0.07$ and $r - i = 0.26 \\pm 0.07$ for NGC 3256E, indicating different stellar populations. These colours correspond to simple stellar population ages of $288^{+11}_{-54}$ Myr and $841^{+125}_{-157}$ Myr for NGC 3256W and NGC 3256E, respectively, suggesting NGC 3256W's diffuse light is dominated by stars formed after the interaction, while light in NGC 3256E is primarily from stars that originated in the host galaxy. Using a mixed stellar population model, we break our diffuse light into two populations: one at 10 Gyr, representing stars pulled from the host galaxies, and a younger component, whose age is determined by fitting the model to the data. We find similar ages ...

  16. Immunocalization of telomerase in cells of lizard tail after amputation suggests cell activation for tail regeneration.

    Science.gov (United States)

    Alibardi, L

    2016-02-01

    Tail amputation (autotomy) in most lizards elicits a remarkable regenerative response leading to a new although simplified tail. No information on the trigger mechanism following wounding is known but cells from the stump initiate to proliferate and form a regenerative blastema. The present study shows that telomerases are mainly activated in the nuclei of various connective and muscle satellite cells of the stump, and in other tissues, probably responding to the wound signals. Western blotting detection also indicates that telomerase positive bands increases in the regenerating blastema in comparison to the normal tail. Light and ultrastructural immunocytochemistry localization of telomerase shows that 4-14 days post-amputation in lizards immunopositive nuclei of sparse cells located among the wounded tissues are accumulating into the forming blastema. These cells mainly include fibroblasts and fat cells of the connective tissue and satellite cells of muscles. Also some immature basophilic and polychromatophilic erytroblasts, lymphoblasts and myelocytes present within the Bone Marrow of the vertebrae show telomerase localization in their nuclei, but their contribution to the formation of the regenerative blastema remains undetermined. The study proposes that one of the initial mechanisms triggering cell proliferation for the formation of the blastema in lizards involve gene activation for the production of telomerase that stimulates the following signaling pathways for cell division and migration.

  17. Growth and respiration of regenerating tissues of the axolotl tail.

    Science.gov (United States)

    Vladimirova, I G

    1975-01-01

    Changes in the weight and oxygen consumption were studied during regeneration of the tail in adult axolotls and larvae. The curve of the increase in weight of the regenerating tail in both age groups is S-shaped. The intensity of respiration of the regenerating tail increases in adult axolotls and in larvae at the blastema stage; in adult axolotls there is also a second increase in the intensity of respiration of the regenerating tail during differentiation of the muscles. The relationship between weight and the rate of respiration was compared during regeneration of the tail in axolotl and the normal growth of the animals. Whereas growth of the animals was characterized by the relationship QO2 equals aPk with a constant value of k, during regeneration the various stages of this process have their own corresponding values of k.

  18. Diagnostic analysis of electrodialysis in mine tailing materials

    DEFF Research Database (Denmark)

    Hansen, Henrik K.; Ribeiro, Alexandra B.; Mateus, Eduardo;

    2007-01-01

    removal results of a soil sampled close to an abandoned cupric pyrite mine-mainly polluted with lead (around 3800ppm) are also presented. The results show that the heavy metals could be mobilized in all three contaminated solid materials using the electrodialytic process. The effect of adding different......Removal of heavy metals from mine tailings and soil contaminated by copper mining activities was studied under batch electrodialytic conditions. Two types of mine tailings were treated: (i) freshly produced tailings coming directly from the flotation process, and (ii) tailings deposited......%. However, water removed only 15% of Ph from the soil, and no Cu from the fresh tailings. The soil fractionation of the metals before and after the experiments was evaluated by sequential chemical extractions, in order to work further on the optimization of the remediation conditions....

  19. Studies on tail length of Rambouillet and Mouflon sheep.

    Science.gov (United States)

    Shelton, M

    1977-01-01

    Data are presented on tail length of various breeds or crosses of sheep and various combinations of Mouflon X Rambouillet breeding. Mouflons sheep had 11 coccygeal vertebrae, and Rambouillet had 18-24. Others were intermediate between these types. Finewool sheep (Merino or Rambouillet) had longer tails than medium wool (Dorset, Suffolk or Hampshire), crossed, or Rambouillet breeds. Heritability estimates for tail length of Rambouillet were 0.387 (intra-sire regression), 0.344 (half-sib method), and 0.706 for inter se matings in a population containing some Mouflon breeding. In the Rambouillet breed, tail length was shown to be correlated with various measures of wool production. However, this relationship was low and only wool covering and staple length were significant. The significance of this to the development of long tails in animals under domestication is discussed.

  20. Radon emanation from backfilled mill tailings in underground uranium mine.

    Science.gov (United States)

    Sahu, Patitapaban; Mishra, Devi Prasad; Panigrahi, Durga Charan; Jha, Vivekananda; Patnaik, R Lokeswara; Sethy, Narendra Kumar

    2014-04-01

    Coarser mill tailings used as backfill to stabilize the stoped out areas in underground uranium mines is a potential source of radon contamination. This paper presents the quantitative assessment of radon emanation from the backfilled tailings in Jaduguda mine, India using a cylindrical accumulator. Some of the important parameters such as (226)Ra activity concentration, bulk density, bulk porosity, moisture content and radon emanation factor of the tailings affecting radon emanation were determined in the laboratory. The study revealed that the radon emanation rate of the tailings varied in the range of 0.12-7.03 Bq m(-2) s(-1) with geometric mean of 1.01 Bq m(-2) s(-1) and geometric standard deviation of 3.39. An increase in radon emanation rate was noticed up to a moisture saturation of 0.09 in the tailings, after which the emanation rate gradually started declining with saturation due to low diffusion coefficient of radon in the saturated tailings. Radon emanation factor of the tailings varied in the range of 0.08-0.23 with the mean value of 0.21. The emanation factor of the tailings with moisture saturation level over 0.09 was found to be about three times higher than that of the absolutely dry tailings. The empirical relationship obtained between (222)Rn emanation rate and (226)Ra activity concentration of the tailings indicated a significant positive linear correlation (r = 0.95, p < 0.001). This relationship may be useful for quick prediction of radon emanation rate from the backfill material of similar nature. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Star Clusters in the Tidal Tails of Interacting Galaxies: Cluster Populations Across a Variety of Tail Environments

    CERN Document Server

    Mullan, B; Kepley, A A; Lee, K H; Charlton, J C; Knierman, K; Bastian, N; Chandar, R; Durrell, P R; Elmegreen, D; English, J; Gallagher, S C; Gronwall, C; Hibbard, J E; Hunsberger, S; Johnson, K E; Maybhate, A; Palma, C; Trancho, G; Vacca, W D

    2011-01-01

    We have searched for compact stellar structures within 17 tidal tails in 13 different interacting galaxies using F606W- and F814W- band images from the Wide Field Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST). The sample of tidal tails includes a diverse population of optical properties, merging galaxy mass ratios, HI content, and ages. Combining our tail sample with Knierman et al. (2003), we find evidence of star clusters formed in situ with Mv < -8.5 and V-I < 2.0 in 10 of 23 tidal tails; we are able to identify cluster candidates to Mv = -6.5 in the closest tails. Three tails offer clear examples of "beads on a string" star formation morphology in V-I color maps. Two tails present both tidal dwarf galaxy (TDG) candidates and cluster candidates. Statistical diagnostics indicate that clusters in tidal tails may be drawn from the same power-law luminosity functions (with logarithmic slopes ~ -2 - -2.5) found in quiescent spiral galaxies and the interiors of interacting systems. We find...

  2. Nesting habitat relationships of sympatric Crested Caracaras, Red-tailed Hawks, and White-tailed Hawks in South Texas

    Science.gov (United States)

    Actkinson, M.A.; Kuvlesky, W.P.; Boal, C.W.; Brennan, L.A.; Hernandez, F.

    2007-01-01

    We quantified nesting-site habitats for sympatric White-tailed Hawks (Buteo albicaudatus) (n = 40), Red-tailed Hawks (B. jamaicensis) (n = 39), and Crested Caracaras (Caracara cheriway) (n = 24) in the Coastal Sand Plain of south Texas. White-tailed Hawks and Crested Caracara nest sites occurred in savannas, whereas Red-tailed Hawk nest sites occurred in woodlands on the edge of savannas. White-tailed Hawk nest sites were in shrubs and trees that were shorter (3.5 ?? 1.0 m) and had smaller canopy diameters (5.5 ?? 2.1 m) than those of Red-tailed Hawks (10.1 ?? 2.0 m, 13.7 ?? 5.8 m) and Crested Caracaras (5.6 ?? 1.7 m, 8.5 ?? 3.5 m). Red-tailed Hawk nest sites had higher woody densities (15.7 ?? 9.6 plants) and more woody cover (84 ?? 19%) than those of White-tailed Hawks (5.6 ?? 5.8 plants, 20 ?? 21%) and Crested Caracaras (9.9 ?? 6.7 plants, 55 ?? 34%). Crested Caracara nest sites were in dense, multi-branched shrubs composed of more living material (97 ?? 3%) than those of White-tailed (88 ?? 18%) and Red-tailed hawks (88 ?? 18%). Nest sites of White-tailed Hawks, Red-tailed Hawks, and Crested Caracaras were similar to random samples from the surrounding habitat indicating that preferred nesting habitat was available for each of these species at least within 60 m of active nest sites. Nest tree height, along with woody plant and native grass cover best discriminated nest sites among the three raptor species. There was no overlap at Red-tailed and White-tailed hawk nest sites in vegetation structure, while Crested Caracara nests were in habitat intermediate between the two other species. Partitioning of nesting habitat may be how these raptor species co-exist at the broader landscape scale of our study area in the Coastal Sand Plain of Texas.

  3. The Oncogenic Fusion Proteins SET-Nup214 and Sequestosome-1 (SQSTM1)-Nup214 Form Dynamic Nuclear Bodies and Differentially Affect Nuclear Protein and Poly(A)+ RNA Export.

    Science.gov (United States)

    Port, Sarah A; Mendes, Adélia; Valkova, Christina; Spillner, Christiane; Fahrenkrog, Birthe; Kaether, Christoph; Kehlenbach, Ralph H

    2016-10-28

    Genetic rearrangements are a hallmark of several forms of leukemia and can lead to oncogenic fusion proteins. One example of an affected chromosomal region is the gene coding for Nup214, a nucleoporin that localizes to the cytoplasmic side of the nuclear pore complex (NPC). We investigated two such fusion proteins, SET-Nup214 and SQSTM1 (sequestosome)-Nup214, both containing C-terminal portions of Nup214. SET-Nup214 nuclear bodies containing the nuclear export receptor CRM1 were observed in the leukemia cell lines LOUCY and MEGAL. Overexpression of SET-Nup214 in HeLa cells leads to the formation of similar nuclear bodies that recruit CRM1, export cargo proteins, and certain nucleoporins and concomitantly affect nuclear protein and poly(A)(+) RNA export. SQSTM1-Nup214, although mostly cytoplasmic, also forms nuclear bodies and inhibits nuclear protein but not poly(A)(+) RNA export. The interaction of the fusion proteins with CRM1 is RanGTP-dependent, as shown in co-immunoprecipitation experiments and binding assays. Further analysis revealed that the Nup214 parts mediate the inhibition of nuclear export, whereas the SET or SQSTM1 part determines the localization of the fusion protein and therefore the extent of the effect. SET-Nup214 nuclear bodies are highly mobile structures, which are in equilibrium with the nucleoplasm in interphase and disassemble during mitosis or upon treatment of cells with the CRM1-inhibitor leptomycin B. Strikingly, we found that nucleoporins can be released from nuclear bodies and reintegrated into existing NPC. Our results point to nuclear bodies as a means of preventing the formation of potentially insoluble and harmful protein aggregates that also may serve as storage compartments for nuclear transport factors.

  4. La-related protein 4 binds poly(A), interacts with the poly(A)-binding protein MLLE domain via a variant PAM2w motif, and can promote mRNA stability.

    Science.gov (United States)

    Yang, Ruiqing; Gaidamakov, Sergei A; Xie, Jingwei; Lee, Joowon; Martino, Luigi; Kozlov, Guennadi; Crawford, Amanda K; Russo, Amy N; Conte, Maria R; Gehring, Kalle; Maraia, Richard J

    2011-02-01

    The conserved RNA binding protein La recognizes UUU-3'OH on its small nuclear RNA ligands and stabilizes them against 3'-end-mediated decay. We report that newly described La-related protein 4 (LARP4) is a factor that can bind poly(A) RNA and interact with poly(A) binding protein (PABP). Yeast two-hybrid analysis and reciprocal immunoprecipitations (IPs) from HeLa cells revealed that LARP4 interacts with RACK1, a 40S ribosome- and mRNA-associated protein. LARP4 cosediments with 40S ribosome subunits and polyribosomes, and its knockdown decreases translation. Mutagenesis of the RNA binding or PABP interaction motifs decrease LARP4 association with polysomes. Several translation and mRNA metabolism-related proteins use a PAM2 sequence containing a critical invariant phenylalanine to make direct contact with the MLLE domain of PABP, and their competition for the MLLE is thought to regulate mRNA homeostasis. Unlike all ∼150 previously analyzed PAM2 sequences, LARP4 contains a variant PAM2 (PAM2w) with tryptophan in place of the phenylalanine. Binding and nuclear magnetic resonance (NMR) studies have shown that a peptide representing LARP4 PAM2w interacts with the MLLE of PABP within the affinity range measured for other PAM2 motif peptides. A cocrystal of PABC bound to LARP4 PAM2w shows tryptophan in the pocket in PABC-MLLE otherwise occupied by phenylalanine. We present evidence that LARP4 expression stimulates luciferase reporter activity by promoting mRNA stability, as shown by mRNA decay analysis of luciferase and cellular mRNAs. We propose that LARP4 activity is integrated with other PAM2 protein activities by PABP as part of mRNA homeostasis.

  5. Quasi-steady state aerodynamics of the cheetah tail

    Directory of Open Access Journals (Sweden)

    Amir Patel

    2016-08-01

    Full Text Available During high-speed pursuit of prey, the cheetah (Acinonyx jubatus has been observed to swing its tail while manoeuvring (e.g. turning or braking but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities.

  6. Quasi-steady state aerodynamics of the cheetah tail

    Science.gov (United States)

    Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily

    2016-01-01

    ABSTRACT During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities. PMID:27412267

  7. Revegetation of Copper Mine Tailings with Ryegrass and Willow

    Institute of Scientific and Technical Information of China (English)

    HAO Xiu-Zhen; ZHOU Dong-Mei; SI You-Bin

    2004-01-01

    To restore vegetation on metal mine tailings is very difficult because they often contain high concentrations of heavy metals, low nutrient content and low water retention capacity. This study involved 3 experiments that evaluated the effects of 4 treatment amendments: montmorillonite, rice straw, organic manure and chemical fertilizer on the growth of ryegrass (Lolium perenne L.) and willow (Saliz viminalis L.) with Cu and Zn mine tailings from two mining areas. The results showed that ryegrass was the most tolerant of 4 crops to Cu toxicity. Also when organic manure, which contained high concentrations of inorganic salts, was added to the mine tailings, it significantly hindered ryegrass growth (P = 0.05).Meanwhile, with ryegrass organic manure significantly increased (P= 0.05) the extractable Cu concentration in both mine tailings. When montmorillonite was used as a mine tailings amendment with willow, the height and tress number at the 1st cut were significantly greater (P =- 0.05) than a control without montmorillonite. However there was no significant difference for height, tress number, dry weight or root dry weight at the 2nd cut. So, amendment applications to reduce metal toxicity and increase nutrients retention in mine tailings were essential during revegetation of mine tailings.

  8. Quasi-steady state aerodynamics of the cheetah tail.

    Science.gov (United States)

    Patel, Amir; Boje, Edward; Fisher, Callen; Louis, Leeann; Lane, Emily

    2016-08-15

    During high-speed pursuit of prey, the cheetah (Acinonyx jubatus) has been observed to swing its tail while manoeuvring (e.g. turning or braking) but the effect of these complex motions is not well understood. This study demonstrates the potential of the cheetah's long, furry tail to impart torques and forces on the body as a result of aerodynamic effects, in addition to the well-known inertial effects. The first-order aerodynamic forces on the tail are quantified through wind tunnel testing and it is observed that the fur nearly doubles the effective frontal area of the tail without much mass penalty. Simple dynamic models provide insight into manoeuvrability via simulation of pitch, roll and yaw tail motion primitives. The inertial and quasi-steady state aerodynamic effects of tail actuation are quantified and compared by calculating the angular impulse imparted onto the cheetah's body and its shown aerodynamic effects contribute to the tail's angular impulse, especially at the highest forward velocities.

  9. Merging Galaxies with Tidal Tails in COSMOS to z=1

    CERN Document Server

    Wen, Z Z

    2016-01-01

    Tidal tails are created in major mergers involving disk galaxies. How the tidal tails trace the assembly history of massive galaxies remains to be explored. We identify a sample of 461 merging galaxies with long tidal tails from 35076 galaxies mass-complete at $M_\\star\\ge 10^{9.5}\\,M_{\\odot}$ and $0.2\\leq z\\leq1$ based on HST/ACS F814W imaging data and public catalogs of the COSMOS field. The long tails refer to these with length equal to or longer than the diameter of their host galaxies. The mergers with tidal tails are selected using our novel $A_{\\rm O}-D_{\\rm O}$ technique for strong asymmetric features together with visual examination. Our results show that the fraction of tidal-tailed mergers evolves mildly with redshift, as $\\sim (1+z)^{2.0\\pm0.4}$, and becomes relatively higher in less massive galaxies out to $z=1$. With a timescale of 0.5 Gyr for the tidal-tailed mergers, we obtain that the occurrence rate of such mergers follows $0.01\\pm 0.007\\,(1+z)^{2.3\\pm 1.4}$ Gyr$^{-1}$ and corresponds to $\\si...

  10. Cassini in Titan's tail: CAPS observations of plasma escape

    Science.gov (United States)

    Coates, A. J.; Wellbrock, A.; Lewis, G. R.; Arridge, C. S.; Crary, F. J.; Young, D. T.; Thomsen, M. F.; Reisenfeld, D. B.; Sittler, E. C., Jr.; Johnson, R. E.; Szego, K.; Bebesi, Z.; Jones, G. H.

    2012-05-01

    We present observations of CAPS electron and ion spectra during Titan distant tail crossings at 5,000-10,000 km altitude by the Cassini spacecraft. In common with closer tail encounters, we identify ionospheric plasma in the tail. Some of the electron spectra indicate a direct magnetic connection to Titan's dayside ionosphere due to the presence of ionospheric photoelectrons. Ion observations reveal heavy (m/q˜ 16 and 28) and light (m/q = 1-2) ion populations streaming into the tail. Using the distant tail encounters T9, T75 and T63, we estimate total plasma loss rates from Titan via this process of (4.2, 0.96 and 2.3) × 1024 ions s-1 respectively for the three encounters, values which are in agreement with some simulations but slightly lower than earlier estimates based on non-differential techniques. Using the mass-separated data, this corresponds to mass loss rates of (8.9, 1.6, 4.0) × 1025 amu s-1 for T9, T75 and T63 respectively, an average loss rate of ˜7 tonnes per Earth day. Remarkably, all of the tail encounters studied here indicate a split tail feature, indicating that this may be a common feature in Titan's interaction with Saturn's magnetosphere.

  11. Microbial biogeochemistry of uranium mill tailings

    Science.gov (United States)

    Landa, Edward R.

    2005-01-01

    Uranium mill tailings (UMT) are the crushed ore residues from the extraction of uranium (U) from ores. Among the radioactive wastes associated with the nuclear fuel cycle, UMT are unique in terms of their volume and their limited isolation from the surficial environment. For this latter reason, their management and long-term fate has many interfaces with environmental microbial communities and processes. The interactions of microorganisms with UMT have been shown to be diverse and with significant consequences for radionuclide mobility and bioremediation. These radionuclides are associated with the U-decay series. The addition of organic carbon and phosphate is required to initiate the reduction of the U present in the groundwater down gradient of the mills. Investigations on sediment and water from the U-contaminated aquifer, indicates that the addition of a carbon source stimulates the rate of U removal by microbial reduction. Moreover, most attention with respect to passive or engineered removal of U from groundwaters focuses on iron-reducing and sulfate-reducing bacteria.

  12. Heavy-tailed distributions and robustness in economics and finance

    CERN Document Server

    Ibragimov, Marat; Walden, Johan

    2015-01-01

    This book focuses on general frameworks for modeling heavy-tailed distributions in economics, finance, econometrics, statistics, risk management and insurance. A central theme is that of (non-)robustness, i.e., the fact that the presence of heavy tails can either reinforce or reverse the implications of a number of models in these fields, depending on the degree of heavy-tailedness. These results motivate the development and applications of robust inference approaches under heavy tails, heterogeneity and dependence in observations. Several recently developed robust inference approaches are discussed and illustrated, together with applications.

  13. Automated classification of tailed bacteriophages according to their neck organization.

    Science.gov (United States)

    Lopes, Anne; Tavares, Paulo; Petit, Marie-Agnès; Guérois, Raphaël; Zinn-Justin, Sophie

    2014-11-27

    The genetic diversity observed among bacteriophages remains a major obstacle for the identification of homologs and the comparison of their functional modules. In the structural module, although several classes of homologous proteins contributing to the head and tail structure can be detected, proteins of the head-to-tail connection (or neck) are generally more divergent. Yet, molecular analyses of a few tailed phages belonging to different morphological classes suggested that only a limited number of structural solutions are used in order to produce a functional virion. To challenge this hypothesis and analyze proteins diversity at the virion neck, we developed a specific computational strategy to cope with sequence divergence in phage proteins. We searched for homologs of a set of proteins encoded in the structural module using a phage learning database. We show that using a combination of iterative profile-profile comparison and gene context analyses, we can identify a set of head, neck and tail proteins in most tailed bacteriophages of our database. Classification of phages based on neck protein sequences delineates 4 Types corresponding to known morphological subfamilies. Further analysis of the most abundant Type 1 yields 10 Clusters characterized by consistent sets of head, neck and tail proteins. We developed Virfam, a webserver that automatically identifies proteins of the phage head-neck-tail module and assign phages to the most closely related cluster of phages. This server was tested against 624 new phages from the NCBI database. 93% of the tailed and unclassified phages could be assigned to our head-neck-tail based categories, thus highlighting the large representativeness of the identified virion architectures. Types and Clusters delineate consistent subgroups of Caudovirales, which correlate with several virion properties. Our method and webserver have the capacity to automatically classify most tailed phages, detect their structural module, assign a

  14. A Comparison of Tail Behaviour of Stock Market Returns

    Directory of Open Access Journals (Sweden)

    Echaust Krzysztof

    2014-06-01

    Full Text Available Most investors believe that left tails of the stock returns distribution are heavier than the right ones. It is a natural consequence of crashes perception as much more turbulent than the booms. Crashes develop in shorter time intervals than booms and changes of prices are significantly bigger. This paper focuses on the extreme behavior of stock market returns. The differences in the tails thickness of distribution are negligible. Its main result is that the differences between tails have been found in the clustering of extremes, especially during the crash of 2007-2009.

  15. Heat Recovery From Tail Gas Incineration To Generate Power

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, Tarek

    2010-09-15

    Many industrial processes result in tail gas wastes that must be flared or incinerated to abide with environmental guidelines. Tail gas incineration occurs in several chemical processes resulting in high-temperature exhaust gas that simply go to the stack, thus wasting all that valuable heat! This paper discusses useful heat recovery and electric power generation utilizing available heat in exhaust gas from tail gas incinerators. This heat will be recovered in a waste-heat recovery boiler that will produce superheated steam to expand in a steam turbine to generate power. A detailed cost estimate is presented.

  16. The Sufferings of "Lousy Tail Shtps"

    Institute of Scientific and Technical Information of China (English)

    Xing Dan

    2012-01-01

    Along with ups and downs of the market, ship owners and ship enterprises are constantly changing their roles. Order depletion under the crisis shadow has torn apart the past serenity enjoyed under prosperous conditions. The news of "lousy tail ships" broke out from time to time which has brought ship enterprises to the edge of the abyss. Under this circumstance, what are those "lousy tail ships" that will become the most favorable for ship owners to purchase at the lowest price? And who are chasing after the lousy tail ships?

  17. An Analysis of a Heuristic Procedure to Evaluate Tail (independence

    Directory of Open Access Journals (Sweden)

    Marta Ferreira

    2014-01-01

    Full Text Available Measuring tail dependence is an important issue in many applied sciences in order to quantify the risk of simultaneous extreme events. A usual measure is given by the tail dependence coefficient. The characteristics of events behave quite differently as these become more extreme, whereas we are in the class of asymptotic dependence or in the class of asymptotic independence. The literature has emphasized the asymptotic dependent class but wrongly infers that tail dependence will result in the overestimation of extreme value dependence and consequently of the risk. In this paper we analyze this issue through simulation based on a heuristic procedure.

  18. A tail-wagging event in comet Austin

    Science.gov (United States)

    Klinglesmith, Daniel A.; Niedner, Malcolm B.; Oliversen, Ronald J.; Westpfahl, David

    1990-01-01

    On the morning of 21 May 1990, a sequence of images of Comet Austin was obtained in the light of H2O+. The filter was centered at 602.5 nm with FWHM of 5.0 nm. At least two waves were followed out through the main ion tail structure. During the course of the observations, 2.5 hours, two new tail rays were seen to form and undergo similar wave motion. Several condensations, possibly representing disconnected material, were seen to develop and move out along the tail ray with a velocity of about 60 km/sec.

  19. Asymptotics of Markov Kernels and the Tail Chain

    CERN Document Server

    Resnick, Sidney I

    2011-01-01

    An asymptotic model for extreme behavior of certain Markov chains is the "tail chain". Generally taking the form of a multiplicative random walk, it is useful in deriving extremal characteristics such as point process limits. We place this model in a more general context, formulated in terms of extreme value theory for transition kernels, and extend it by formalizing the distinction between extreme and non-extreme states. We make the link between the update function and transition kernel forms considered in previous work, and we show that the tail chain model leads to a multivariate regular variation property of the finite-dimensional distributions under assumptions on the marginal tails alone.

  20. Comparison between availability of heavy metals in dry and wetland tailing of an abandoned copper tailing pond.

    Science.gov (United States)

    Das, Manab; Maiti, S K

    2008-02-01

    Wetland sediments are generally considered as a sink for metals and, in the anoxic zone, may contain very high concentrations of heavy metals in reduced state. A comprehensive study was carried out to compare the differences of total, environmentally available (Env-Av), HOAC, EDTA and DTPA available heavy metal fraction in tailing of the marshy area of a copper tailing pond and the dry tailing. The average concentrations of all the seven metals in the wetland tailing were found higher than dry tailing. Regarding pH, organic carbon, available (correction of availailable) N, P and K also found higher in marshy wetland tailing compare to the dry tailing. This information is needed in order to understand wetland system and to assure that wetlands do not themselves eventually become sources of metal contamination to surrounding areas. But as levels of pollutants increases, the ability of a wetland system to incorporate waste can be impaired and the wetland can become a source of toxicity.

  1. Star formation in shocked cluster spirals and their tails

    CERN Document Server

    Roediger, E; Owers, M S; Ebeling, H; Sun, M

    2014-01-01

    Recent observations of ram pressure stripped spiral galaxies in clusters revealed details of the stripping process, i.e., the truncation of all interstellar medium (ISM) phases and of star formation (SF) in the disk, and multiphase star-forming tails. Some stripped galaxies, in particular in merging clusters, develop spectacular star-forming tails, giving them a jellyfish-like appearance. In merging clusters, merger shocks in the intra-cluster medium (ICM) are thought to have overrun these galaxies, enhancing the ambient ICM pressure and thus triggering SF, gas stripping and tail formation. We present idealised hydrodynamical simulations of this scenario, including standard descriptions for SF and stellar feedback. To aid the interpretation of recent and upcoming observations, we focus on particular structures and dynamics in SF patterns in the remaining gas disk and in the near tails, which are easiest to observe. The observed jellyfish morphology is qualitatively reproduced for, both, face-on and edge-on st...

  2. Impact of mine tailings on surrounding soils: Case

    African Journals Online (AJOL)

    H. ABDURAHMAN

    Article Number: AD77AF156458. ISSN 1996-0786 ... Key words: Contamination, heavy metals, soils, mine area, mine tailings, Marrakech – Morocco. INTRODUCTION ... thallium, and iron are transported to the environment (Lee and Kao, 2004 ...

  3. Influences of wetland plants on weathered acidic mine tailings

    Energy Technology Data Exchange (ETDEWEB)

    Eva Stoltz; Maria Greger [Stockholm University, Stockholm (Sweden). Department of Botany

    2006-11-15

    Establishment of Carex rostrata, Eriophorum angustifolium and Phragmites australis on weathered, acidic mine tailings (pH {approximately} 3) and their effect on pH in tailings were investigated in a field experiment. The amendments, sewage sludge and an ashes-sewage sludge mixture, were used as plant nutrition and their influence on the metal and As concentrations of plant shoots was analysed. An additional experiment was performed in greenhouse with E. angustifolium and sewage sludge as amendments in both weathered and unweathered tailings. After one year, plants grew better in amendments containing ashes in the field, also in those plants the metal and As shoot concentrations were generally lower than in other treatments. After two years, the only surviving plants were found in sewage sludge mixed with ashes. No effect on pH by plants was found in weathered acidic mine tailings in either field- or greenhouse experiment.

  4. Western Red-tailed Skink Distribution in Southern Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Hall, D. B. and Gergor, P. D.

    2011-11-01

    This slide show reports a study to: determine Western Red-tailed Skink (WRTS) distribution on Nevada National Security Site (NNSS); identify habitat where WRTS occur; learn more about WRTS natural history; and document distribution of other species.

  5. A Note on Trans-Planckian Tail Effects

    CERN Document Server

    Graef, L L

    2015-01-01

    We study the proposal by Mersini et al. that the observed dark energy might be explained by the back-reaction of the set of tail modes in a theory with a dispersion relation in which the mode frequency decays exponentially in the trans-Planckian regime. The matter tail modes are frozen out, however they induce metric fluctuations. The energy-momentum tensor with which the tail modes effect the background geometry obtains contributions from both metric and matter fluctuations. We calculate the equation of state induced by the tail modes taking into account the gravitational contribution. We find that, in contrast to the case of frozen super-Hubble cosmological fluctuations, in this case the matter perturbations dominate, and they yield an equation of state which to leading order takes the form of a positive cosmological constant.

  6. A note on trans-Planckian tail effects

    Science.gov (United States)

    Graef, L. L.; Brandenberger, R.

    2015-09-01

    We study the proposal by Mersini et al. [1] that the observed dark energy might be explained by the back-reaction of the set of tail modes in a theory with a dispersion relation in which the mode frequency decays exponentially in the trans-Planckian regime. The matter tail modes are frozen out, however they induce metric fluctuations. The energy-momentum tensor with which the tail modes effect the background geometry obtains contributions from both metric and matter fluctuations. We calculate the equation of state induced by the tail modes taking into account the gravitational contribution. We find that, in contrast to the case of frozen super-Hubble cosmological fluctuations, in this case the matter perturbations dominate, and they yield an equation of state which to leading order takes the form of a positive cosmological constant.

  7. St. Vincent Island White-Tailed Deer Monitoring Program

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The white tailed deer herd on St. Vincent Island represents an important part of the island's biotic community. To maintain the integrity of the island's deer...

  8. Population Density Influences Dispersal in Female White-Tailed Deer

    National Research Council Canada - National Science Library

    Clayton L. Lutz; Duane R. Diefenbach; Christopher S. Rosenberry

    2015-01-01

    .... To test this hypothesis, we conducted a meta-analysis of female dispersal rates from 12 populations of white-tailed deer and predicted dispersal rate and distance were positively related to deer density...

  9. Processing of tailings in Canadian oil sands industry

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Vast amounts of tailings are produced daily in bitumen extraction from the Athabasca oil sands. The coarse sand from the tailings stream is used to build dykes around the containment basin. The run-off slurry arrives at the water's edge in the tailings pond at a solids concentration of about 3%~8% by mass. Settling of the solids takes place "relatively fast", over several days, creating a "free water zone" that contains little solids. When the fine mineral solids concentration has reached about 15% by mass, the suspension develops non-Newtonian properties. After 2~3 years, the suspension concentration reaches a value of about 30% by mass at which the settling rate becomes extremely slow. Methods to handle the already created tailings ponds and new approaches to eliminate the creation of new ones will be discussed both from the industrial and fundamental prospective.

  10. Design of the Modulator the CTF3 Tail Clipper Kicker

    CERN Document Server

    Barnes, M J; Ravida, G; Ueda, A

    2007-01-01

    The goal of the present CLIC Test Facility (CTF3) is to demonstrate the technical feasibility of specific key issues in the CLIC scheme. The extracted beam from the combiner ring (CR), of 35 A in magnitude and 140 ns duration, is sent to the new CLic EXperimental area (CLEX) facility. A Tail Clipper (TC) is required, in the CR to CLEX transfer line, to allow the duration of the extracted beam pulse to be adjusted. It is proposed to use a stripline kicker for the tail clipper, with each of the deflector plates driven to equal but opposite potential. The tail clipper kick must have a fast rise-time, of not more than 5 ns, in order to minimize uncontrolled beam loss. Several different options are being investigated to meet the demanding specifications for the modulator of the tail clipper. This paper discusses options considered for the fast, high voltage, semiconductor switches and shows results of initial tests on the switches.

  11. Anisotropic Electron Tail Generation during Tearing Mode Magnetic Reconnection

    Science.gov (United States)

    DuBois, Ami M.; Almagri, Abdulgader F.; Anderson, Jay K.; Den Hartog, Daniel J.; Lee, John David; Sarff, John S.

    2017-02-01

    The first experimental evidence of anisotropic electron energization during magnetic reconnection that favors a direction perpendicular to the guide magnetic field in a toroidal, magnetically confined plasma is reported in this Letter. Magnetic reconnection plays an important role in particle heating, energization, and transport in space and laboratory plasmas. In toroidal devices like the Madison Symmetric Torus, discrete magnetic reconnection events release large amounts of energy from the equilibrium magnetic field. Fast x-ray measurements imply a non-Maxwellian, anisotropic energetic electron tail is formed at the time of reconnection. The tail is well described by a power-law energy dependence. The expected bremsstrahlung from an electron distribution with an anisotropic energetic tail (v⊥>v∥ ) spatially localized in the core region is consistent with x-ray emission measurements. A turbulent process related to tearing fluctuations is the most likely cause for the energetic electron tail formation.

  12. Thyroxine Induced Resorption of Xenopus Laevis Tail Tissue in Vitro.

    Science.gov (United States)

    Scadding, Steven R.

    1984-01-01

    A simple method of studying thyroxine-induced resorption of tadpole tails in vitro is described. This procedure demonstrates that resorption is dependent on thyroxine and requires protein synthesis. It introduces students to the use of tissue culture methods. (Author)

  13. A note on trans-Planckian tail effects

    Energy Technology Data Exchange (ETDEWEB)

    Graef, L.L. [Department of Physics, McGill University,3600 University Street, Montréal, QC, H3A 2T8 (Canada); Instituto de Física, Universidade de São Paulo, Rua do Matão travessa R, São Paulo, SP, 05508-090 (Brazil); Brandenberger, R. [Department of Physics, McGill University,3600 University Street, Montréal, QC, H3A 2T8 (Canada)

    2015-09-09

    We study the proposal by Mersini et al. http://dx.doi.org/10.1103/PhysRevD.64.043508 that the observed dark energy might be explained by the back-reaction of the set of tail modes in a theory with a dispersion relation in which the mode frequency decays exponentially in the trans-Planckian regime. The matter tail modes are frozen out, however they induce metric fluctuations. The energy-momentum tensor with which the tail modes effect the background geometry obtains contributions from both metric and matter fluctuations. We calculate the equation of state induced by the tail modes taking into account the gravitational contribution. We find that, in contrast to the case of frozen super-Hubble cosmological fluctuations, in this case the matter perturbations dominate, and they yield an equation of state which to leading order takes the form of a positive cosmological constant.

  14. Method to Quantify Tail Vein Injection Technique in Small Animals

    National Research Council Canada - National Science Library

    Groman, Ernest V; Reinhardt, Christopher P

    2004-01-01

    .... In this report, we propose six criteria for a reagent designed to assess tail vein injection technique in small animals and suggest a reagent, colloidal gold labeled with the stable isotope 197Au...

  15. FOREST COVER INFLUENCES DISPERSAL DISTANCE OF WHITE-TAILED DEER

    National Research Council Canada - National Science Library

    Eric S. Long; Duane R. Diefenbach; Christopher S. Rosenberry; Bret D. Wallingford; Marrett D. Grund

    2005-01-01

    ...) in 2 study areas in Pennsylvania. By using a meta-analysis approach, we compared dispersal rates and distances from these populations together with published reports of 10 other nonmigratory populations of white-tailed deer...

  16. The price of portfolio selection under tail conditional expectation with ...

    African Journals Online (AJOL)

    The price of portfolio selection under tail conditional expectation with consumption cost and transaction cost. ... Log in or Register to get access to full text downloads. ... Asset-liability control; Value-at-risk; consumption cost; Transaction costs.

  17. IT LONG TAIL STRATEGY FOR SOFTWARE PACKAGE COMPANY

    Directory of Open Access Journals (Sweden)

    Andreas Winata

    2010-10-01

    Full Text Available Long Tail Strategy is a business strategy which explains that the total revenue from the sale of non-popular products may exceed the total income from popular products. This may happen since generally there is only a small number of popular products, which is in great demand, while there are many of the non-popular types which is sold in small amounts. This research aims to better understand the role of IT behind the success of the Long Tail strategy. Results show stages of how to develop IT strategy, including identification, analysis, determines on a strategy, until implementation. The results of this study will help software developers to plan IT strategy by implementing an accurate Long Tail Strategy.Keywords: Long Tail, IT Strategy, Services, Software Package

  18. Risk Management - Variance Minimization or Lower Tail Outcome Elimination

    DEFF Research Database (Denmark)

    Aabo, Tom

    2002-01-01

    This paper illustrates the profound difference between a risk management strategy of variance minimization and a risk management strategy of lower tail outcome elimination. Risk managers concerned about the variability of cash flows will tend to center their hedge decisions on their best guess...... on future cash flows (the budget), while risk managers concerned about costly lower tail outcomes will hedge (considerably) less depending on the level of uncertainty. A risk management strategy of lower tail outcome elimination is in line with theoretical recommendations in a corporate value......-adding perspective. A cross-case study of blue-chip industrial companies partly supports the empirical use of a risk management strategy of lower tail outcome elimination but does not exclude other factors from (co-)driving the observations....

  19. Testing tail-mounted transmitters with Myocastor coypus (nutria)

    Science.gov (United States)

    Merino, S.; Carter, J.; Thibodeaux, G.

    2007-01-01

    We developed a tail-mounted radio-transmitter for Myocastor coypus (nutria) that offers a practical and efficient alternative to collar or implant methods. The mean retention time was 96 d (range 57-147 d, n = 7), making this a practical method for short-term studies. The tail-mounts were less injurious to animals than collars and easier for field researchers to implement than either collars or surgically implanted transmitters.

  20. Vegetation successfully prevents oxidization of sulfide minerals in mine tailings.

    Science.gov (United States)

    Li, Yang; Sun, Qingye; Zhan, Jing; Yang, Yang; Wang, Dan

    2016-07-15

    The oxidization of metal sulfide in tailings causes acid mine drainage. However, it remains unclear whether vegetation prevents the oxidization of metal sulfides. The oxidization characteristics and microbial indices of the tailings in the presence of various plant species were investigated to explore the effects of vegetation on the oxidization of sulfide minerals in tailings. The pH, reducing sulfur, free iron oxides (Fed), chemical oxygen consumption (COC) and biological oxygen consumption (BOC) were measured. Key iron- and sulfur-oxidizing bacteria (Acidithiobacillus spp., Leptospirillum spp. and Thiobacillus spp.) were quantified using real-time PCR. The results indicate that vegetation growing on tailings can effectively prevent the oxidization of sulfide minerals in tailings. A higher pH and reducing-sulfur content and lower Fed were observed in the 0-30 cm depth interval in the presence of vegetation compared to bare tailings (BT). The COC gradually decreased with depth in all of the soil profiles; specifically, the COC rapidly decreased in the 10-20 cm interval in the presence of vegetation but gradually decreased in the BT profiles. Imperata cylindrica (IC) and Chrysopogon zizanoides (CZ) profiles contained the highest BOC in the 10-20 cm interval. The abundance of key iron- and sulfur-oxidizing bacteria in the vegetated tailings were significantly lower than in the BT; in particular, IC was associated with the lowest iron- and sulfur-oxidizing bacterial abundance. In conclusion, vegetation successfully prevented the oxidization of sulfide minerals in the tailings, and Imperata cylindrica is the most effective in reducing the number of iron- and sulfur-oxidizing bacteria and helped to prevent the oxidization of sulfide minerals in the long term. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Complex mineral recovery from the copper flotation tailing

    OpenAIRE

    Krstev, Boris; Golomeov, Blagoj

    2005-01-01

    The generally concept of the carried out investigations is discovering an appropriate technological scheme of the possible complex mineral utilisation from the copper flotation tailing. The Bucim - mine laboratory investigations of the flotation tailing are based on the demands of the possible complex recovery from the useful present minerals or mineral components: CuFeS2; FeS2; Fe2O3; Fe3O4; Na-feldspar and K-feldspar; SiO2 etc.

  2. Pricing aspect of valuable metals from tailing dumps

    OpenAIRE

    Bugarin, Mile; Slavković, Gordana; Marinković, Vladan

    2011-01-01

    The last decade is characterized with the trend of higher prices of ferrous and precious metals on the world markets. Copper, gold and silver have been produced for centuries in the Bor mining complex. Flotation tailing dumps were created by copper mining and processing with tested contents of valuable metals. Tailing dumps with significant content of metals can be exploitated and useful raw materials can be evaluated. This paper discusses the pricing aspect of these raw materials or price mo...

  3. A tale of two "tails:" A curiosity revisited

    Directory of Open Access Journals (Sweden)

    Nishanth Sadashiva

    2016-01-01

    Full Text Available A human tail or a caudal appendage is a rare condition with preconceived notions and stigmata. They could be either true tails or "pseudotails" based on their embryology. Clinically, they are considered as a marker of occult spinal dysraphism. We report two such cases with tethering of cord, one of which was associated with a lipomeningomyelocele. These patients are in need of meticulous evaluation and appropriate management.

  4. Assessment of Phytostabilization Success in Metalliferous Acid Mine Tailings

    Science.gov (United States)

    Wang, Y.; Root, R. A.; Hammond, C.; Amistadi, M. K.; Maier, R. M.; Chorover, J.

    2014-12-01

    Legacy mine tailings are a significant source of metal(loid)s due to wind and water erosion, especially in the arid southwest, and exposure to fugative dusts presents a health risk to surrounding populations. Compost assisted phytostabilization has been implemented to reduce off site emissions at the Iron King Mine U.S. Superfund Site in central Arizona, concurrent with a greenhouse mesocosm study for detailed study of subsurface mechanisms. Quantification of plant available toxic metal(loid)s in the amended tailings was accessed with a targeted single extraction of diethylenetriaminepentaactic acid (DTPA). Greenhouse mesocosms (1m dia, 0.4 m deep), run in triplicate, mimicked field treatments with: i) tailings only control (TO), ii) tailings plus 15 wt% compost (TC), iii) TC + quailbush seeds (TCA), and iv) TC + buffalo grass seeds (TCB). Core samples collected at 3-month intervals for 1 year were dissected by depth (10 cm each) for analysis. DTPA results indicated that compost treated samples decreased plant availability of Al, As, Cd, Cu, Fe, and Pb but increased Mn and Zn compared with TO. TCB decreased plant available metal(loid)s at all depths, whereas TCA plant available Al, As, Cd, Cu, Fe, Mn and Zn increased in the deeper 20-30cm and 30-40 cm relative to TCB. Samples from the greenhouse were compared to tailings from both the field site and tailings impacted soils used to grow vegetables. Mineral transformations and metal complexation, in the pre- and post-extracted tailings were analyzed by synchrotron transmission XRD and FTIR spectroscopy. The temporal change in plant available metal(loid)s in response to phytostabilization indicates mineralogical alteration that improves soil quality by reducing plant available metal(loid)s. These results will aid in the understanding and efficacy of phytostabilization as a means of remediating and reducing toxicity on mine tailings as well as providing information on health risk management in the region.

  5. [The metaphoric image of the "tail of a comet"].

    Science.gov (United States)

    Wackenheim, A

    1994-01-01

    The author places the metaphoric image of "comet tail" in the semiotic structural and triadic system of Peirce. This metaphoric image utilises the iconic quality of "resemblance". The discussion of the image of "comet tail" gives the author the opportunity to distinguish three varieties. One variety is static (example: round atelectasia), the other is dynamic (example: cancer of the breast) and the third is artificial (sonographic artifact).

  6. Power-like Tail Observed in Weight Distributions of Schoolchildren

    CERN Document Server

    Kuninaka, Hiroto

    2015-01-01

    We investigated the statistical properties of the weight distributions of Japanese children who were born in 1996, from recent data. The weights of 16- and 17-year-old male children have a lognormal distribution with a power-like tail, which is best modeled by the double Pareto distribution. The emergence of the power-like tail may be attributed to the low probability that an obese person will attain a normal weight.

  7. Evidence for bacteriophage T7 tail extension during DNA injection

    Directory of Open Access Journals (Sweden)

    Hakala Kevin W

    2008-06-01

    Full Text Available Abstract Background Electron micrographs of bacteriophage T7 reveal a tail shorter than needed to reach host cytoplasm during infection-initiating injection of a T7 DNA molecule through the tail and cell envelope. However, recent data indicate that internal T7 proteins are injected before the DNA molecule is injected. Thus, bacteriophage/host adsorption potentially causes internal proteins to become external and lengthen the tail for DNA injection. But, the proposed adsorption-induced tail lengthening has never been visualized. Findings In the present study, electron microscopy of particles in T7 lysates reveals a needle-like capsid extension that attaches partially emptied bacteriophage T7 capsids to non-capsid vesicles and sometimes enters an attached vesicle. This extension is 40–55 nm long, 1.7–2.4× longer than the T7 tail and likely to be the proposed lengthened tail. The extension is 8–11 nm in diameter, thinner than most of the tail, with an axial hole 3–4 nm in diameter. Though the bound vesicles are not identified by microscopy, these vesicles resemble the major vesicles in T7 lysates, found to be E. coli outer membrane vesicles by non-denaturing agarose gel electrophoresis, followed by mass spectrometry. Conclusion The observed lengthened tail is long enough to reach host cytoplasm during DNA injection. Its channel is wide enough to be a conduit for DNA injection and narrow enough to clamp DNA during a previously observed stalling/re-starting of injection. However, its outer diameter is too large to explain formation by passing of an intact assembly through any known capsid hole unless the hole is widened.

  8. Scoring tail damage in pigs: an evaluation based on recordings at Swedish slaughterhouses

    Directory of Open Access Journals (Sweden)

    Keeling Linda J

    2012-05-01

    Full Text Available Abstract Background There is increasing interest in recording tail damage in pigs at slaughter to identify problem farms for advisory purposes, but also for benchmarking within and between countries as part of systematic monitoring of animal welfare. However, it is difficult to draw conclusions when comparing prevalence’s between studies and countries partly due to differences in management (e.g. differences in tail docking and enrichment routines and partly due to differences in the definition of tail damage. Methods Tail damage and tail length was recorded for 15,068 pigs slaughtered during three and four consecutive days at two slaughterhouses in Sweden. Tail damage was visually scored according to a 6-point scale and tail length was both visually scored according to a 5-point scale and recorded as tail length in centimetres for pigs with injured or shortened tails. Results The total prevalence of injury or shortening of the tail was 7.0% and 7.2% in slaughterhouse A and B, respectively. When only considering pigs with half or less of the tail left, these percentages were 1.5% and 1.9%, which is in line with the prevalence estimated from the routine recordings at slaughter in Sweden. A higher percentage of males had injured and/or shortened tails, and males had more severely bitten tails than females. Conclusions While the current method to record tail damage in Sweden was found to be reliable as a method to identify problem farms, it clearly underestimates the actual prevalence of tail damage. For monitoring and benchmarking purposes, both in Sweden and internationally, we propose that a three graded scale including both old and new tail damage would be more appropriate. The scale consists of one class for no tail damage, one for mild tail damage (injured or shortened tail with more than half of the tail remaining and one for severe tail damage (half or less of the tail remaining.

  9. Synthesis process of forsterite refractory by iron ore tailings.

    Science.gov (United States)

    Li, Jing; Wang, Qi; Liu, Jihui; Li, Peng

    2009-01-01

    With mineral resources becoming gradually more deficient, as well as the issue of mine tailings causing environmental pollution, more and more people have realized the great significance of tailings utilization. Iron ore tailings, as a kind of secondary resource, have been developed in recycling industries. The feasibility to produce forsterite refractory from high-silicon iron tailings and high-magnesium raw materials were discussed. Also, the synthesis reaction processes were studied from the results of the laboratory experiments. The experiments showed that the synthesis processes can be separated into three steps when using iron tailings to synthesize forsterite: (1) produce magnesium iron sosoloid (Mg(1-X)Fe(X)O) and magnesium metasilicate (MgSiO3), (2) form the fayalite, and (3) create the forsterite. The synthetic productions are primarily forsterite, hortonolite, and small amounts of magnesium metasilicate (MgSiO3). The hortonolite is wrapped around the surface of the forsterite particles and formed the cementing phase. In addition, the method to produce forsterite refractory and lightweight forsterite refractory from iron tailings were offered.

  10. Long velocity tails in plasmas and gravitational systems

    CERN Document Server

    Brenig, L; Filho, T M Rocha

    2016-01-01

    Long tails in the velocity distribution are observed in plasmas and gravitational systems. Some experiments and observations in far-from-equilibrium conditions show that these tails behave as 1/v^(5/2). We show here that such heavy tails are due to a universal mechanism related to the fluctuations of the total force field. Owing to the divergence in 1/r^2 of the binary interaction force, these fluctuations can be very large and their probability density exhibits a similar long tail. They induce large velocity fluctuations leading to the 1/v^(5/2) tail. We extract the mechanism causing these properties from the BBGKY hierarchy representation of Statistical Mechanics. This leads to a modification of the Vlasov equation by an additional term. The novel term involves a fractional power 3/4 of the Laplacian in velocity space and a fractional iterated time integral. Solving the new kinetic equation for a uniform system, we retrieve the observed 1/v^(5/2) tail for the velocity distribution. These results are confirm...

  11. Geochemical Characterization of Copper Tailings after Legume Revegetation

    Directory of Open Access Journals (Sweden)

    Justine Perry T. Domingo

    2014-12-01

    Full Text Available Knowledge on the geochemistry of mine tailings is important in understanding the challenges in establishing vegetation cover on tailings dumps and mined out areas. In this study, the mineralogy and trace element composition of copper tailings were examined. Two legume species, Calopogonium mucunoides and Centrosema molle, were utilized to investigate the possible effects of these plants in the geochemical development of mine tailings into soil-like material. The initial mineralogical and chemical analysis of the tailings samples indicated poor conditions for plant growth—minimal levels of major nutrients and organic matter as well as elevated copper concentrations. Despite these conditions, the two legume species exhibited good growth rates. Both legumes have likewise signif icantly reduced heavy metal concentrations in the tailings, indicating the possibility of metal hyperaccumulation in the plant tissue. The mineral composition has been retained even after revegetation; nevertheless, breakdown of primary minerals and subsequent formation of clay minerals were detected. These results provide insights on the transformation of toxic materials into habitable substrates for sustained plant growth.

  12. Preparation of polymeric aluminium ferric chloride from bauxite tailings

    Directory of Open Access Journals (Sweden)

    Ma D.

    2013-01-01

    Full Text Available Bauxite tailings are the main solid wastes in the ore dressing process. The Al2O3 and Fe2O3 contents in bauxite tailings can reach 50% and 13% respectively. The present study proposed a feasible method to use bauxite tailings to prepare polymeric aluminium ferric chloride (PAFC, a new composite inorganic polymer for water purification. Bauxite tailings roasted reacting with hydrochloric acid under air, pickle liquor which mainly contains Fe3+, Al3+ was generated, then calcium aluminate was used to adjust pH value and the basicity of the pickle liquor, the PAFC was subsequently prepared after the polymerization process. The optimal synthesizing parameters for the preparation of PAFC obtained were as follows: the concentration of hydrochloric acid of 24 wt%, ratio of hydrochloric acid to bauxite tailings of 6:1, temperature of 90ºC, leaching time of 2.5 hours, ration of pickle liquor to calcium aluminate of 12:1, polymerization temperature of 90ºC and polymerization time of about 3 hours. The basicity of PAFC was higher than 68%, the sum concentration of Al2O3 and Fe2O3 was beyond 12.5%. The results of flocculation tests indicate that the PAFC has a better performance of removing the turbidity of wastewater compared to PAC, and PAFC prepared by bauxite tailings is a kind of high quality flocculants.

  13. Julia Butler Hansen NWR: Initial Survey Instructions for Columbian White-tailed Deer:Black-tailed Deer Ratio Protocol

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The lower Columbia population of Columbian White-tailed deer CWTD—Odocoileus virginianus leucurus) is an endangered population that has undergone a dramatic...

  14. Naturally occurring hybrids derived from γ-amino acids and sugars with potential tail to tail ether-bonds

    Science.gov (United States)

    Feng, Zi-Ming; Zhan, Zhi-Lai; Yang, Ya-Nan; Jiang, Jian-Shuang; Zhang, Pei-Cheng

    2016-05-01

    The basic substances of life include various amino acids and sugars. To search such molecules is the precondition to understand the essential nature. Here we reported four unprecedented hybrids of γ-amino acids and sugars from the roots of Ranunculus ternatus, which possess potential tail to tail ether-connected (6,6-ether-connected) modes in the sugar moiety. The structures of these hybrids were elucidated by extensive analyses of spectra and calculated electronic circular dichroism (ECD) method.

  15. Tail growth tracks the ontogeny of prehensile tail use in capuchin monkeys (Cebus albifrons and C. apella).

    Science.gov (United States)

    Russo, Gabrielle A; Young, Jesse W

    2011-11-01

    Physical anthropologists have devoted considerable attention to the structure and function of the primate prehensile tail. Nevertheless, previous morphological studies have concentrated solely on adults, despite behavioral evidence that among many primate taxa, including capuchin monkeys, infants and juveniles use their prehensile tails during a greater number and greater variety of positional behaviors than do adults. In this study, we track caudal vertebral growth in a mixed longitudinal sample of white-fronted and brown capuchin monkeys (Cebus albifrons and Cebus apella). We hypothesized that young capuchins would have relatively robust caudal vertebrae, affording them greater tail strength for more frequent tail-suspension behaviors. Our results supported this hypothesis. Caudal vertebral bending strength (measured as polar section modulus at midshaft) scaled to body mass with negative allometry, while craniocaudal length scaled to body mass with positive allometry, indicating that infant and juvenile capuchin monkeys are characterized by particularly strong caudal vertebrae for their body size. These findings complement previous results showing that long bone strength similarly scales with negative ontogenetic allometry in capuchin monkeys and add to a growing body of literature documenting the synergy between postcranial growth and the changing locomotor demands of maturing animals. Although expanded morphometric data on tail growth and behavioral data on locomotor development are required, the results of this study suggest that the adult capuchin prehensile-tail phenotype may be attributable, at least in part, to selection on juvenile performance, a possibility that deserves further attention. Copyright © 2011 Wiley-Liss, Inc.

  16. Autotrophic biofilm development on superficial samples of the gold-silver mine tailings, Valenciana (Mexico): pioneers in tailings remediation?

    Science.gov (United States)

    García-Meza, Jessica Viridiana

    2008-01-01

    We report the results of long term bio-assays on microorganism colonization of mine tailings samples, taken from the Valenciana mine tailings (Guanajuato, Mexico), under stable laboratory conditions (humidity, temperature, light exposure). In order to identify the main metabolic groups of the potentially colonizing microorganisms and the implications of their growth on the main tailing's characteristics related to biological succession, organic matter (OM) content, cationic exchange capacity (CEC), and pH values were measured as the colonization took place. We observe that photosynthetic biofilms (cyanobacteria, green algae, and diatoms) successfully colonize the mine tailings samples as pioneers; moreover, bacteria, yeast and fungi were also identified. Biofilm colonization significantly improved the OM contents, whereas the pH value is not modified during the entire observed colonization process. The results suggest that biofilms are useful during the first steps of the mine tailings remediation. This is the first report of microalgae and cyanobacteria grown of on tailings samples obtained from a semiarid region.

  17. Tail-scope: Using friends to estimate heavy tails of degree distributions in large-scale complex networks

    CERN Document Server

    Eom, Young-Ho

    2014-01-01

    Many complex networks in natural and social phenomena have often been characterized by heavy-tailed degree distributions. However, due to rapidly growing size of network data and concerns on privacy issues about using these data, it becomes more difficult to analyze complete data sets. Thus, it is crucial to devise effective and efficient estimation methods for heavy tails of degree distributions in large-scale networks only using local information of a small fraction of sampled nodes. Here we propose a tail-scope method based on local observational bias of the friendship paradox. We show that the tail-scope method outperforms the uniform node sampling for estimating heavy tails of degree distributions, while the opposite tendency is observed in the range of small degrees. In order to take advantages of both sampling methods, we devise the hybrid method that successfully recovers the whole range of degree distributions. Our tail-scope method shows how structural heterogeneities of large-scale complex networks...

  18. Tail-scope: Using friends to estimate heavy tails of degree distributions in large-scale complex networks

    Science.gov (United States)

    Eom, Young-Ho; Jo, Hang-Hyun

    2015-05-01

    Many complex networks in natural and social phenomena have often been characterized by heavy-tailed degree distributions. However, due to rapidly growing size of network data and concerns on privacy issues about using these data, it becomes more difficult to analyze complete data sets. Thus, it is crucial to devise effective and efficient estimation methods for heavy tails of degree distributions in large-scale networks only using local information of a small fraction of sampled nodes. Here we propose a tail-scope method based on local observational bias of the friendship paradox. We show that the tail-scope method outperforms the uniform node sampling for estimating heavy tails of degree distributions, while the opposite tendency is observed in the range of small degrees. In order to take advantages of both sampling methods, we devise the hybrid method that successfully recovers the whole range of degree distributions. Our tail-scope method shows how structural heterogeneities of large-scale complex networks can be used to effectively reveal the network structure only with limited local information.

  19. Is rhizosphere remediation sufficient for sustainable revegetation of mine tailings?

    Science.gov (United States)

    Huang, Longbin; Baumgartl, Thomas; Mulligan, David

    2012-01-01

    Background Revegetation of mine tailings (fine-grained waste material) starts with the reconstruction of root zones, consisting of a rhizosphere horizon (mostly topsoil and/or amended tailings) and the support horizon beneath (i.e. equivalent to subsoil – mostly tailings), which must be physically and hydro-geochemically stable. This review aims to discuss key processes involved in the development of functional root zones within the context of direct revegetation of tailings and introduces a conceptual process of rehabilitating structure and function in the root zones based on a state transition model. Scope Field studies on the revegetation of tailings (from processing base metal ore and bauxite residues) are reviewed. Particular focus is given to tailings' properties that limit remediation effectiveness. Aspects of root zone reconstruction and vegetation responses are also discussed. Conclusions When reconstructing a root zone system, it is critical to restore physical structure and hydraulic functions across the whole root zone system. Only effective and holistically restored systems can control hydro-geochemical mobility of acutely and chronically toxic factors from the underlying horizon and maintain hydro-geochemical stability in the rhizosphere. Thereafter, soil biological capacity and ecological linkages (i.e. carbon and nutrient cycling) may be rehabilitated to integrate the root zones with revegetated plant communities into sustainable plant ecosystems. A conceptual framework of system transitions between the critical states of root zone development has been proposed. This will illustrate the rehabilitation process in root zone reconstruction and development for direct revegetation with sustainable plant communities. Sustainable phytostabilization of tailings requires the systematic consideration of hydro-geochemical interactions between the rhizosphere and the underlying supporting horizon. It further requires effective remediation strategies to

  20. Evaluation of pyritic mine tailings as a plant growth substrate.

    Science.gov (United States)

    Roseby, Stuart J; Kopittke, Peter M; Mulligan, David R; Menzies, Neal W

    2017-10-01

    At the Kidston gold mine, Australia, the direct establishment of vegetation on tailings was considered as an alternative to the use of a waste rock cover. The tailings acid/base account was used to predict plant growth limitation by acidity, and thus methods capable of identifying tailings that would acidify to pH 4.5 or lower were sought. Total S was found to be poorly correlated with acid-generating sulfide, and total C was poorly correlated with acid-neutralizing carbonate, precluding the use of readily determined total S and C as predictors of net acid generation. Therefore, the selected approach used assessment of sulfide content as a predictor of acid generation, and carbonate content as a measure of the acid-neutralizing capacity available at pH 5 and above. Using this approach, the majority of tailings (67%) were found to be non-acid generating. However, areas of potentially acid-generating tailings were randomly distributed across the dam, and could only be located by intensive sampling. The limitations imposed by the large sample numbers, and costly analysis of sulfide and carbonate, make it impractical to identify and ameliorate acid-generating areas prior to vegetation establishment. However, as only a small proportion of the tailings will acidify, a strategy of re-treating acid areas following oxidation is suggested. The findings of the present study will assist in the selection of appropriate methods for the prediction of net acid generation, particularly where more conservative measurements are required to allow vegetation to be established directly in tailings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Auroral counterpart of magnetic field dipolarizations in Saturn's tail

    Science.gov (United States)

    Jackman, C. M.; Badman, S. V.; Achilleos, N.; Bunce, E. J.; Cowley, S. W. H.; Radioti, A.; Grodent, D.; Dougherty, M. K.; Pryor, W.

    2012-04-01

    Following magnetic reconnection in a planetary magnetotail, newly closed field lines can be rapidly accelerated back towards the planet, becoming "dipolarized" in the process. At Saturn, dipolarizations can be initially identified in magnetometer data by looking for a southward turning of the magnetic field, indicating the transition from a radially stretched configuration to a more dipolar field topology. The highly stretched geometry of the kronian magnetotail lobes gives rise to a tail current which flows eastward (dusk to dawn) in the near equatorial plane across the centre of the tail. During reconnection and associated dipolarization of the field, the inner edge of this tail current can be diverted through the ionosphere, in a situation analogous to the substorm current wedge picture at Earth. We present a picture of the current circuit arising from this tail reconfiguration, and outline the equations which govern the field-current relationship. We show an example of a dipolarization identified in the Cassini magnetometer data and use this formalism to constrain the ionospheric current density that would arise for this example and the implications for auroral electron acceleration in regions of upward directed field-aligned current. We then present a separate example of data from the Cassini UVIS instrument where we observe small 'spots' of auroral emission lying near the main oval; features thought to be associated with dipolarizations in the tail. In the example shown, such auroral spots are the precursor to more intense activity associated with recurrent energisation via particle injections from the tail following reconnection. We conclude that dipolarizations in Saturn's magnetotail have an observable auroral counterpart, opening up the possibility to search for further examples and to use this auroral property as a remote proxy for tail reconnection.

  2. Tail Docking and Ear Cropping Dogs: Public Awareness and Perceptions.

    Directory of Open Access Journals (Sweden)

    Katelyn E Mills

    Full Text Available Tail docking and ear cropping are two surgical procedures commonly performed on many dog breeds. These procedures are classified as medically unnecessary surgeries whose purpose is primarily cosmetic. Available attitude research surrounding these controversial practices has been limited to surveys of veterinarians and dog breeders familiar with both practices. The aim of this project was to: 1 assess public awareness of tail docking and ear cropping, 2 determine whether physical alteration of a dog affects how the dog, and 3 owner are perceived. In Experiment 1 awareness was measured using a combination of both explicit and implicit measures. We found that 42% of participants (n = 810 were unable to correctly explain the reason why tail docked and ear cropped dogs had short ears and tails. Similarly, an implicit measure of awareness ('nature vs nurture task', found that the majority of participants believed short tails and erect ears were a consequence of genetics rather than something the owner or breeder had done. The results obtained in Experiment 2 (n = 392 provide evidence that ear cropped and tail docked dogs are perceived differently than an identical dog in its 'natural' state. Modified dogs were perceived as being more aggressive, more dominant, less playful and less attractive than natural dogs. Experiment 3 (n = 410 is the first evidence that owners of modified dogs are perceived as being more aggressive, more narcissistic, less playful, less talkative and less warm compared to owners of natural dogs. Taken together, these results suggest that although a significant proportion of subjects appear unaware of the practices of tail docking and ear cropping in dogs, these procedures have significant impacts on how modified dogs and their owners are perceived by others.

  3. Tail Docking and Ear Cropping Dogs: Public Awareness and Perceptions.

    Science.gov (United States)

    Mills, Katelyn E; Robbins, Jesse; von Keyserlingk, Marina A G

    2016-01-01

    Tail docking and ear cropping are two surgical procedures commonly performed on many dog breeds. These procedures are classified as medically unnecessary surgeries whose purpose is primarily cosmetic. Available attitude research surrounding these controversial practices has been limited to surveys of veterinarians and dog breeders familiar with both practices. The aim of this project was to: 1) assess public awareness of tail docking and ear cropping, 2) determine whether physical alteration of a dog affects how the dog, and 3) owner are perceived. In Experiment 1 awareness was measured using a combination of both explicit and implicit measures. We found that 42% of participants (n = 810) were unable to correctly explain the reason why tail docked and ear cropped dogs had short ears and tails. Similarly, an implicit measure of awareness ('nature vs nurture task'), found that the majority of participants believed short tails and erect ears were a consequence of genetics rather than something the owner or breeder had done. The results obtained in Experiment 2 (n = 392) provide evidence that ear cropped and tail docked dogs are perceived differently than an identical dog in its 'natural' state. Modified dogs were perceived as being more aggressive, more dominant, less playful and less attractive than natural dogs. Experiment 3 (n = 410) is the first evidence that owners of modified dogs are perceived as being more aggressive, more narcissistic, less playful, less talkative and less warm compared to owners of natural dogs. Taken together, these results suggest that although a significant proportion of subjects appear unaware of the practices of tail docking and ear cropping in dogs, these procedures have significant impacts on how modified dogs and their owners are perceived by others.

  4. Is rhizosphere remediation sufficient for sustainable revegetation of mine tailings?

    Science.gov (United States)

    Huang, Longbin; Baumgartl, Thomas; Mulligan, David

    2012-07-01

    Revegetation of mine tailings (fine-grained waste material) starts with the reconstruction of root zones, consisting of a rhizosphere horizon (mostly topsoil and/or amended tailings) and the support horizon beneath (i.e. equivalent to subsoil - mostly tailings), which must be physically and hydro-geochemically stable. This review aims to discuss key processes involved in the development of functional root zones within the context of direct revegetation of tailings and introduces a conceptual process of rehabilitating structure and function in the root zones based on a state transition model. Field studies on the revegetation of tailings (from processing base metal ore and bauxite residues) are reviewed. Particular focus is given to tailings' properties that limit remediation effectiveness. Aspects of root zone reconstruction and vegetation responses are also discussed. When reconstructing a root zone system, it is critical to restore physical structure and hydraulic functions across the whole root zone system. Only effective and holistically restored systems can control hydro-geochemical mobility of acutely and chronically toxic factors from the underlying horizon and maintain hydro-geochemical stability in the rhizosphere. Thereafter, soil biological capacity and ecological linkages (i.e. carbon and nutrient cycling) may be rehabilitated to integrate the root zones with revegetated plant communities into sustainable plant ecosystems. A conceptual framework of system transitions between the critical states of root zone development has been proposed. This will illustrate the rehabilitation process in root zone reconstruction and development for direct revegetation with sustainable plant communities. Sustainable phytostabilization of tailings requires the systematic consideration of hydro-geochemical interactions between the rhizosphere and the underlying supporting horizon. It further requires effective remediation strategies to develop hydro-geochemically stable

  5. Black-tailed and white-tailed jackrabbits in the American West: History, ecology, ecological significance, and survey methods

    Science.gov (United States)

    Simes, Matthew; Longshore, Kathleen; Nussear, Kenneth E.; Beatty, Greg L.; Brown, David E.; Esque, Todd C.

    2015-01-01

    Across the western United States, Leporidae are the most important prey item in the diet of Golden Eagles (Aquila chrysaetos). Leporids inhabiting the western United States include black-tailed (Lepus californicus) and white-tailed jackrabbits (Lepus townsendii) and various species of cottontail rabbit (Sylvilagus spp.). Jackrabbits (Lepus spp.) are particularly important components of the ecological and economic landscape of western North America because their abundance influences the reproductive success and population trends of predators such as coyotes (Canis latrans), bobcats (Lynx rufus), and a number of raptor species. Here, we review literature pertaining to black-tailed and white-tailed jackrabbits comprising over 170 published journal articles, notes, technical reports, conference proceedings, academic theses and dissertations, and other sources dating from the late 19th century to the present. Our goal is to present information to assist those in research and management, particularly with regard to protected raptor species (e.g., Golden Eagles), mammalian predators, and ecological monitoring. We classified literature sources as (1) general information on jackrabbit species, (2) black-tailed or (3) white-tailed jackrabbit ecology and natural history, or (4) survey methods. These categories, especially 2, 3, and 4, were further subdivided as appropriate. The review also produced several tables on population trends, food habits, densities within various habitats, and jackrabbit growth and development. Black-tailed and white-tailed jackrabbits are ecologically similar in general behaviors, use of forms, parasites, and food habits, and they are prey to similar predators; but they differ in their preferred habitats. While the black-tailed jackrabbit inhabits agricultural land, deserts, and shrublands, the white-tailed jackrabbit is associated with prairies, alpine tundra, and sagebrush-steppe. Frequently considered abundant, jackrabbit numbers in western North

  6. Copula-EVT Based Tail Dependence Structure of Financial Markets in China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Tail dependence structure model based on Copula theory and extreme value theory (EVT) is constructed to picture the tail correlation of financial time series more exact. The empirical research results show that the Gumbel Copula can fit the upper and lower tail dependence structures of Shanghai A share index and Shenzhen A share index, and correlation of upper tails of both indices is stronger than that of lower-tails.

  7. Reactivity of the isolated perfused rat tail vascular bed

    Directory of Open Access Journals (Sweden)

    A.S. França

    1997-07-01

    Full Text Available Isolated segments of the perfused rat tail artery display a high basal tone when compared to other isolated arteries such as the mesenteric and are suitable for the assay of vasopressor agents. However, the perfusion of this artery in the entire tail has not yet been used for functional studies. The main purpose of the present study was to identify some aspects of the vascular reactivity of the rat tail vascular bed and validate this method to measure vascular reactivity. The tail severed from the body was perfused with Krebs solution containing different Ca2+ concentrations at different flow rates. Rats were anesthetized with sodium pentobarbital (65 mg/kg and heparinized (500 U. The tail artery was dissected near the tail insertion, cannulated and perfused with Krebs solution plus 30 µM EDTA at 36oC and 2.5 ml/min and the procedures were started after equilibration of the perfusion pressure. In the first group a dose-response curve to phenylephrine (PE (0.5, 1, 2 and 5 µg, bolus injection was obtained at different flow rates (1.5, 2.5 and 3.5 ml/min. The mean perfusion pressure increased with flow as well as PE vasopressor responses. In a second group the flow was changed (1.5, 2, 2.5, 3 and 3.5 ml/min at different Ca2+ concentrations (0.62, 1.25, 2.5 and 3.75 mM in the Krebs solution. Increasing Ca2+ concentrations did not alter the flow-pressure relationship. In the third group a similar protocol was performed but the rat tail vascular bed was perfused with Krebs solution containing PE (0.1 µg/ml. There was an enhancement of the effect of PE with increasing external Ca2+ and flow. PE vasopressor responses increased after endothelial damage with air and CHAPS, suggesting an endothelial modulation of the tone of the rat tail vascular bed. These experiments validate the perfusion of the rat tail vascular bed as a method to investigate vascular reactivity

  8. The microbiology of oil sands tailings: past, present, future.

    Science.gov (United States)

    Foght, Julia M; Gieg, Lisa M; Siddique, Tariq

    2017-05-01

    Surface mining of enormous oil sands deposits in northeastern Alberta, Canada since 1967 has contributed greatly to Canada's economy but has also received negative international attention due largely to environmental concerns and challenges. Not only have microbes profoundly affected the composition and behavior of this petroleum resource over geological time, they currently influence the management of semi-solid tailings in oil sands tailings ponds (OSTPs) and tailings reclamation. Historically, microbial impacts on OSTPs were generally discounted, but next-generation sequencing and biogeochemical studies have revealed unexpectedly diverse indigenous communities and expanded our fundamental understanding of anaerobic microbial functions. OSTPs that experienced different processing and management histories have developed distinct microbial communities that influence the behavior and reclamation of the tailings stored therein. In particular, the interactions of Deltaproteobacteria and Firmicutes with methanogenic archaea impact greenhouse gas emissions, sulfur cycling, pore water toxicity, sediment biogeochemistry and densification, water usage and the trajectory of long-term mine waste reclamation. This review summarizes historical data; synthesizes current understanding of microbial diversity and activities in situ and in vitro; predicts microbial effects on tailings remediation and reclamation; and highlights knowledge gaps for future research. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Simulating deposition of high density tailings using smoothed particle hydrodynamics

    Science.gov (United States)

    Babaoglu, Yagmur; Simms, Paul H.

    2017-08-01

    Tailings are a slurry of silt-sized residual material derived from the milling of rock. High density (HD) tailings are tailings that have been sufficiently dewatered to a point where they exhibit a yield stress upon deposition. They form gently sloped stacks on the surface when deposited; this eliminates or minimizes the need for dams or embankments for containment. Understanding the flow behaviour of high density tailings is essential for estimating the final stack geometry and overall slope angle. This paper focuses on modelling the flow behaviour of HD tailings using smoothed particle hydrodynamics (SPH) method incorporating a `bi-viscosity' model to simulate the non-Newtonian behaviour. The model is validated by comparing the numerical results with bench scale experiments simulating single or multi-layer deposits in two-dimensions. The results indicate that the model agreed fairly well with the experimental work, excepting some repulsion of particles away from the bottom boundary closer to the toe of the deposits. Novel aspects of the work, compared to other simulation of Bingham fluids by SPH, are the simulation of multilayer deposits and the use of a stopping criteria to characterize the rest state.

  10. Green remediation of tailings from the mine using inorganic agents

    Directory of Open Access Journals (Sweden)

    Došić Aleksandar D.

    2017-01-01

    Full Text Available Increasing amounts of residues and waste materials coming from industrial activities in different processes have become an increasingly urgent problem for the future. The paper presents the problem of mine tailings generated in mine “Sase” (Republic of Srpska, Bosnia and Herzegovina with high metal content (Pb, Cu and Zn. Dumpsite of this tailing represents potential risk for water bodies in the vicinity of this location. Chosen treatment process was stabilization/solidification (S/S. Inorganic agents used in this study were fly ash and red mud that represent secondary industrial waste generated on locations relatively near the mine. Therefore, their application can be used as an example of a sustainable solution of regional environmental problem. Further investigations are related to the impact of various factors on metals leaching from mine tailings solidified/stabilized material using the above mentioned immobilization agents. The performance of the immobilizing procedures was examined using several leaching tests: ANS 16.1, TCLP, DIN, MWLP. The results indicated that all S/S samples can be considered as non-hazardous waste, as all leached metal concentrations met the set criteria. These results will further enable the modelling of metals behaviour during long-term leaching from treated mine tailing. The data are invaluable in terms of economically and environmentally sound management of mine tailing.

  11. Influences of wetland plants on weathered acidic mine tailings

    Energy Technology Data Exchange (ETDEWEB)

    Stoltz, Eva [Department of Botany, Stockholm University, Lilla Frescativaegen 5, S-106 91 Stockholm (Sweden)]. E-mail: eva.stoltz@botan.su.se; Greger, Maria [Department of Botany, Stockholm University, Lilla Frescativaegen 5, S-106 91 Stockholm (Sweden)]. E-mail: maria.greger@botan.su.se

    2006-11-15

    Establishment of Carex rostrata, Eriophorum angustifolium and Phragmites australis on weathered, acidic mine tailings (pH {approx}3) and their effect on pH in tailings were investigated in a field experiment. The amendments, sewage sludge and an ashes-sewage sludge mixture, were used as plant nutrition and their influence on the metal and As concentrations of plant shoots was analysed. An additional experiment was performed in greenhouse with E. angustifolium and sewage sludge as amendments in both weathered and unweathered tailings. After one year, plants grew better in amendments containing ashes in the field, also in those plants the metal and As shoot concentrations were generally lower than in other treatments. After two years, the only surviving plants were found in sewage sludge mixed with ashes. No effect on pH by plants was found in weathered acidic mine tailings in either field- or greenhouse experiment. - Wetland plant establishment on acidic mine tailings may contribute to a reduced metal release and a stabilisation of pH.

  12. Evolution of Acid Mine Drainage Formation in Sulphidic Mine Tailings

    Directory of Open Access Journals (Sweden)

    Bernhard Dold

    2014-07-01

    Full Text Available Sulphidic mine tailings are among the largest mining wastes on Earth and are prone to produce acid mine drainage (AMD. The formation of AMD is a sequence of complex biogeochemical and mineral dissolution processes. It can be classified in three main steps occurring from the operational phase of a tailings impoundment until the final appearance of AMD after operations ceased: (1 During the operational phase of a tailings impoundment the pH-Eh regime is normally alkaline to neutral and reducing (water-saturated. Associated environmental problems include the presence of high sulphate concentrations due to dissolution of gypsum-anhydrite, and/or effluents enriched in elements such as Mo and As, which desorbed from primary ferric hydroxides during the alkaline flotation process. (2 Once mining-related operations of the tailings impoundment has ceased, sulphide oxidation starts, resulting in the formation of an acidic oxidation zone and a ferrous iron-rich plume below the oxidation front, that re-oxidises once it surfaces, producing the first visible sign of AMD, i.e., the precipitation of ferrihydrite and concomitant acidification. (3 Consumption of the (reactive neutralization potential of the gangue minerals and subsequent outflow of acidic, heavy metal-rich leachates from the tailings is the final step in the evolution of an AMD system. The formation of multi-colour efflorescent salts can be a visible sign of this stage.

  13. Results of evaluation of tailing dumps dust intensity

    Directory of Open Access Journals (Sweden)

    Masloboev V. A.

    2016-03-01

    Full Text Available A set of most acceptable and well-known methods of dust intensity evaluation has been defined and tested (dependence of Westphal D. L. et al. and DEAD scheme based on the analysis of exiting approaches (deserts, tailing dumps, etc.. The description of the chosen methods has been given. The determination of dynamic velocity u* and velocity at the height of +10 m above the dusting surface u10 which are necessary to evaluate the dust intensity has been demonstrated. The method is based on two-dimensional numerical model of atmosphere aerodynamics in the area of "tailing dumps of ANOF-2 ‒ the town of Apatity". The study provides calculations of horizontal velocity at the height of +10 m above the dusting surface at the wind speed varying from 5 to 23 m/sec. The work also suggests the results of graphical data processing related to tailing grain size distribution from the surface of the firmly established surface of the tailing dumps of ANOF-2. Comparative analysis has been given and the peculiarities of interval (based on grains sizes dust intensity of the tailing dumps of ANOF-2 have been shown using the dependence of Westphal D. L. et al. and DEAD scheme within the wind speed range. The received values of dust intensity at the lower range limit are close to the "maximum specific dust off" value which is used by project specialists for documentation development

  14. Tail dependence and information flow: Evidence from international equity markets

    Science.gov (United States)

    Al Rahahleh, Naseem; Bhatti, M. Ishaq; Adeinat, Iman

    2017-05-01

    Bhatti and Nguyen (2012) used the copula approach to measure the tail dependence between a number of international markets. They observed that some country pairs exhibit only left-tail dependence whereas others show only right-tail. However, the flow of information from uni-dimensional (one-tail) to bi-dimensional (two-tails) between various markets was not accounted for. In this study, we address the flow of information of this nature by using the dynamic conditional correlation (DCC-GARCH) model. More specifically, we use various versions of the DCC models to explain the nexus between the information flow of international equity and to explain the stochastic forward vs. backward dynamics of financial markets based on data for a 15-year period comprising 3,782 observations. We observed that the information flow between the US and Hong Kong markets and between the US and Australian markets are bi-directional. We also observed that the DCC model captures a wider co-movement structure and inter-connectedness compared to the symmetric Joe-Clayton copula.

  15. On the polarization properties of magnetar giant flare pulsating tails

    CERN Document Server

    Yang, Yuan-Pei

    2015-01-01

    Three giant flares have been detected so far from soft gamma-ray repeaters, each characterized by an initial short hard spike and a pulsating tail. The observed pulsating tails are characterized by a duration of $\\sim100\\,\\rm{s}$, an isotropic energy of $\\sim 10^{44}\\,\\rm{erg}$, and a pulse period of a few seconds. The pulsating tail emission likely originates from the residual energy after the intense energy release during the initial spike, which forms a trapped fireball composed of a photon-pair plasma in a closed field line region of the magnetars. Observationally the spectra of pulsating tails can be fitted by the superposition of a thermal component and a power-law component, with the thermal component dominating the emission in the early and late stages of the pulsating tail observations. In this paper, assuming that the trapped fireball is from a closed field line region in the magnetosphere, we calculate the atmosphere structure of the optically-thick trapped fireball and the polarization properties ...

  16. On the statistical properties and tail risk of violent conflicts

    Science.gov (United States)

    Cirillo, Pasquale; Taleb, Nassim Nicholas

    2016-06-01

    We examine statistical pictures of violent conflicts over the last 2000 years, providing techniques for dealing with the unreliability of historical data. We make use of a novel approach to deal with fat-tailed random variables with a remote but nonetheless finite upper bound, by defining a corresponding unbounded dual distribution (given that potential war casualties are bounded by the world population). This approach can also be applied to other fields of science where power laws play a role in modeling, like geology, hydrology, statistical physics and finance. We apply methods from extreme value theory on the dual distribution and derive its tail properties. The dual method allows us to calculate the real tail mean of war casualties, which proves to be considerably larger than the corresponding sample mean for large thresholds, meaning severe underestimation of the tail risks of conflicts from naive observation. We analyze the robustness of our results to errors in historical reports. We study inter-arrival times between tail events and find that no particular trend can be asserted. All the statistical pictures obtained are at variance with the prevailing claims about "long peace", namely that violence has been declining over time.

  17. PSR J0357+3205: the tail of the turtle

    CERN Document Server

    Marelli, Martino; Salvetti, David; Sartore, Nicola; Sartori, Angelica; Caraveo, Patrizia; Pizzolato, Fabio; Parkinson, Pablo M Saz; Belfiore, Andrea

    2013-01-01

    Using a new XMM-Newton observation, we have characterized the X-ray properties of the middle-aged radio-quiet gamma-ray pulsar J0357+3205 (named Morla) and its tail. The X-ray emission from the pulsar is consistent with a magnetospheric non-thermal origin plus a thermal emission from a hot spot (or hot spots). The lack of a thermal component from the whole surface makes Morla the coldest neutron star in its age range. We found marginal evidence for a double-peaked modulation of the X-ray emission. The study of the 9'-long tail confirmed the lack of extended emission near the pulsar itself. The tail shows a very asymmetric brightness profile and its spectrum lacks any spatial variation. We found the nebular emission to be inconsistent with a classical bow-shock, ram-pressure dominated pulsar wind nebula. We propose thermal bremsstrahlung as an alternative mechanism for Morla's tail emission. In this scenario, the tail emission comes from the shocked interstellar medium (ISM) material heated up to X-ray tempera...

  18. Compound action potential of sensory tail nerves in the rat.

    Science.gov (United States)

    Leandri, Massimo; Saturno, Moreno; Cilli, Michele; Bisaglia, Michela; Lunardi, Gianluigi

    2007-01-01

    Assessment of the conduction velocity of motor fibers of the rat tail nerves has been used by some authors in the past, but very little is known about the sensory fibers. In 10 adult rats, weighing between 320 and 380 g, responses from the nerves and muscles of the tail have been recorded after stimulation at its root and tip. It was found that stimulation of the tip involved mainly sensory fibers, of which two main groups could be identified. One faster group, conducting within the range of 38-27 m/s, and one slower group with range 14-7 m/s. The bipolar recording configuration was found to be optimal for sensory recording. Stimulation of the tail root evoked a motor response, which was preceded by a very small neurographic activity, due to the fastest sensory fibers conducting antidromically. The conduction velocity of motor fibers was calculated to be approximately 19 m/s. Distance traveled by the volley can be assessed with excellent precision on the tail nerves; hence the calculated conduction velocities are highly reliable and reproducible. We propose that the tail nerves may be a useful tool for evaluation of conduction velocity of Abeta and Adelta afferents. As the technique is just minimally invasive, the test can be repeated a number of times in animals under chronic experimental conditions.

  19. Electrodialytic remediation of copper mine tailings: Comparing different operational conditions

    DEFF Research Database (Denmark)

    Rojo, Adrian; Hansen, Henrik K.; Ottosen, Lisbeth M.

    2006-01-01

    This work compares and evaluates sixteen electrodialytic laboratory remediation experiments on copper mine tailings. Different parameters were analyzed, such as remediation time, voltage drop, addition of desorbing agents, and the use of pulsed electrical fields. The results show that electric...... current could remove copper from watery tailings slowly. With addition of sulphuric acid, the process was improved due to a pH decrease from 6.7 to around 4, and the copper by this reason was released in the solution. Moreover, with citric acid addition the process was further improved due to a formation...... of copper citrate complexes. Using pulsed electric fields the remediation process with sulphuric acid addition was also improved by a decrease in the polarization cell. Main results: considering remediation with watery tailing as the base line, for three weeks experiments no copper removal was observed...

  20. Asphalt emulsion sealing of uranium mill tailings. 1980 annual report

    Energy Technology Data Exchange (ETDEWEB)

    Hartley, J.N.; Koehmstedt, P.L; Esterl, D.J.; Freeman, H.D.; Buelt, J.L.; Nelson, D.A.; Elmore, M.R.

    1981-05-01

    Studies of asphalt emulsion sealants conducted by the Pacific Northwest Laboratory have demonstrated that the sealants are effective in containing radon and other potentially hazardous material within uranium tailings. The laboratory and field studies have further demonstrated that radon exhalation from uranium tailings piles can be reduced by greater than 99% to near background levels. Field tests at the tailings pile in Grand Junction, Colorado, confirmed that an 8-cm admix seal containing 22 wt% asphalt could be effectively applied with a cold-mix paver. Other techniques were successfully tested, including a soil stabilizer and a hot, rubberized asphalt seal that was applied with a distributor truck. After the seals were applied and compacted, overburden was applied over the seal to protect the seal from ultraviolet degradation.

  1. News from the Library: The 'long tail' Library

    CERN Multimedia

    CERN Library

    2012-01-01

    "The term 'long tail' has gained popularity in recent times as describing the retailing strategy of selling a large number of unique items with relatively small quantities sold of each usually in addition to selling fewer popular items in large quantities. The long tail was popularized by Chris Anderson, who mentioned Amazon.com, Apple and Yahoo! as examples of businesses applying this strategy." *   If we leave the business environment and move to the world of libraries, we still see this "long tail". Usually, only a small portion of a library's book collection accounts for the majority of its loans. On the other hand, there are a variety of "niche information needs" that might not be met, as libraries cannot afford to build up huge collections of documents available just-in-case. However, the networked environment of today's libraries can offer a solution. Online networks of libraries ca...

  2. Cassini/CAPS Observations of Tail Dynamics at Saturn

    Science.gov (United States)

    Thomsen, M. F.; Tokar, R. L.; Wilson, R. J.; Jackman, C. M.

    2013-12-01

    Following up a recent study of the density and flow direction of plasmas in Saturn's premidnight tail, we apply the same methodology to examine Cassini's near- and post-midnight tail passes as well. Specifically, we focus on intervals when CAPS was able to view both inward and outward plasma flows, and we examine the spatial distribution and other properties of such flows. We compare our results with those found by McAndrews et al. [Plasma in Saturn's nightside magnetosphere and the implications for global circulation, Plan. Sp. Sci. (2009)], using a different approach to the analysis of Cassini/CAPS data. These observations provide important clues to Saturn's tail structure and dynamics.

  3. The Anatomy of the Long Tail of Consumer Demand

    Science.gov (United States)

    Broder, Andrei

    The long tail of consumer demand is consistent with two fundamentally different theories. The first, and more popular hypothesis, is that a majority of consumers have similar tastes and only few have any interest in niche content; the second, is that everyone is a bit eccentric, consuming both popular and niche products. By examining extensive data on user preferences for movies, music, web search, and web browsing, we found overwhelming support for the latter theory. Our investigation suggests an additional factor in the success of "infinite-inventory" retailers such as Netflix and Amazon: besides the significant revenue obtained from tail sales, tail availability may boost head sales by offering consumers the convenience of "one-stop shopping" for both their mainstream and niche interests.

  4. The Heads and Tails of Buoyant Autocatalytic Balls

    CERN Document Server

    Rogers, Michael C

    2012-01-01

    Buoyancy produced by autocatalytic reaction fronts can produce fluid flows that advect the front position, giving rise to interesting feedback between chemical and hydrodynamic effects. In a large diameter, extended cylinder that is relatively free of boundary constraints, localized initiation of an iodate-arsenous acid (IAA) reaction front on the bottom boundary generates a rising autocatalytic plume. Such plumes have several differences from their non-reactive counterparts. Using numerical simulation, we have found that if reaction is initiated using a spherical ball of product solution well above the bottom boundary, the subsequent flow can evolve much like an autocatalytic plume: the ball develops a reacting head and tail that is akin to the head and conduit of an autocatalytic plume, except that the tail is disconnected from the boundary. In the limit of large initial autocatalytic balls, however, growth of a reacting tail is suppressed and the resemblance to plumes disappears. Conversely, very small bal...

  5. Cytoplasmic tail of coronavirus spike protein has intracellular targeting signals

    Indian Academy of Sciences (India)

    JIBIN SADASIVAN; MANMEET SINGH; JAYASRI DAS SARMA

    2017-06-01

    Intracellular trafficking and localization studies of spike protein from SARS and OC43 showed that SARS spikeprotein is localized in the ER or ERGIC compartment and OC43 spike protein is predominantly localized in thelysosome. Differential localization can be explained by signal sequence. The sequence alignment using Clustal Wshows that the signal sequence present at the cytoplasmic tail plays an important role in spike protein localization. Aunique GYQEL motif is identified at the cytoplasmic terminal of OC43 spike protein which helps in localization in thelysosome, and a novel KLHYT motif is identified in the cytoplasmic tail of SARS spike protein which helps in ER orERGIC localization. This study sheds some light on the role of cytoplasmic tail of spike protein in cell-to-cell fusion,coronavirus host cell fusion and subsequent pathogenicity.

  6. Commingled uranium-tailings study. Volume II. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    None

    1982-06-30

    Public Law 96-540, Section 213, directs the Secretary of Energy to develop a plan for a cooperative program to provide assistance in the stabilization and management of defense-related uranium mill tailings commingled with other tailings. In developing the plan, the Secretary is further directed to: (1) establish the amount and condition of tailings generated under federal contracts; (2) examine appropriate methodologies for establishing the extent of federal assistance; and (3) consult with the owners and operators of each site. This technical report summarizes US Department of Energy (DOE) and contractor activities in pursuit of items (1), (2), and (3) above. Recommendations regarding policy and a cooperative plan for federal assistance are under separate cover as Volume I.

  7. Martingale Couplings and Bounds on the Tails of Probability Distributions

    CERN Document Server

    Luh, Kyle J

    2011-01-01

    Hoeffding has shown that tail bounds on the distribution for sampling from a finite population with replacement also apply to the corresponding cases of sampling without replacement. (A special case of this result is that binomial tail bounds apply to the corresponding hypergeometric tails.) We give a new proof of Hoeffding's result by constructing a martingale coupling between the sampling distributions. This construction is given by an explicit combinatorial procedure involving balls and urns. We then apply this construction to create martingale couplings between other pairs of sampling distributions, both without replacement and with "surreplacement" (that is, sampling in which not only is the sampled individual replaced, but some number of "copies" of that individual are added to the population).

  8. Environmental Risk Assessment System for Phosphogypsum Tailing Dams

    Directory of Open Access Journals (Sweden)

    Xin Sun

    2013-01-01

    Full Text Available This paper may be of particular interest to the readers as it provides a new environmental risk assessment system for phosphogypsum tailing dams. In this paper, we studied the phosphogypsum tailing dams which include characteristics of the pollution source, environmental risk characteristics and evaluation requirements to identify the applicable environmental risk assessment methods. Two analytical methods, that is, the analytic hierarchy process (AHP and fuzzy logic, were used to handle the complexity of the environmental and nonquantitative data. Using our assessment method, different risk factors can be ranked according to their contributions to the environmental risk, thereby allowing the calculation of their relative priorities during decision making. Thus, environmental decision-makers can use this approach to develop alternative management strategies for proposed, ongoing, and completed PG tailing dams.

  9. Understanding the Heavy Tailed Dynamics in Human Behavior

    CERN Document Server

    Ross, Gordon J

    2015-01-01

    The recent availability of electronic datasets containing large volumes of communication data has made it possible to study human behavior on a larger scale than ever before. From this, it has been discovered that across a diverse range of data sets, the inter-event times between consecutive communication events obey heavy tailed power law dynamics. Explaining this has proved controversial, and two distinct hypotheses have emerged. The first holds that these power laws are fundamental, and arise from the mechanisms such as priority queuing that humans use to schedule tasks. The second holds that they are a statistical artifact which only occur in aggregated data when features such as circadian rhythms and burstiness are ignored. We use a large social media data set to test these hypotheses, and find that although models that incorporate circadian rhythms and burstiness do explain part of the observed heavy tails, there is residual unexplained heavy tail behavior which suggests a more fundamental cause. Based ...

  10. Environmental risk assessment system for phosphogypsum tailing dams.

    Science.gov (United States)

    Sun, Xin; Ning, Ping; Tang, Xiaolong; Yi, Honghong; Li, Kai; Zhou, Lianbi; Xu, Xianmang

    2013-01-01

    This paper may be of particular interest to the readers as it provides a new environmental risk assessment system for phosphogypsum tailing dams. In this paper, we studied the phosphogypsum tailing dams which include characteristics of the pollution source, environmental risk characteristics and evaluation requirements to identify the applicable environmental risk assessment methods. Two analytical methods, that is, the analytic hierarchy process (AHP) and fuzzy logic, were used to handle the complexity of the environmental and nonquantitative data. Using our assessment method, different risk factors can be ranked according to their contributions to the environmental risk, thereby allowing the calculation of their relative priorities during decision making. Thus, environmental decision-makers can use this approach to develop alternative management strategies for proposed, ongoing, and completed PG tailing dams.

  11. A case of tail self-mutilation in a cat

    Directory of Open Access Journals (Sweden)

    Zita Talamonti

    2017-03-01

    Full Text Available The present report describes a case of distal tail self-mutilation in a 5-year-old neutered male domestic short-hair cat. The cat started licking his tail few months before the behavioural visit. Because of the severity of the self-induced injuries, the veterinarian performed a surgical partial caudectomy. After 3 months, the excessive self-grooming of the tail recurred. Neurological and dermatological examinations, radiographs, urine and blood tests did not show any abnormalities. During the behavioural visit, through direct observation of the cat’s posture and behavioural history, the pet received a diagnosis of psychogenic alopecia. The cat was treated with clomipramine for 2 months (0.5 mg/kg/PO SID along with behaviour modification and environmental changes. After 1 month, the cat no longer showed excessive self-grooming. Even if no other systemic pathologies were identified, it is always recommended to address these patients with a multidisciplinary approach.

  12. ANALYZING FAT-TAILED DISTRIBUTIONS IN EMERGING CAPITAL MARKETS

    Directory of Open Access Journals (Sweden)

    FELICIA RAMONA BIRĂU

    2013-05-01

    Full Text Available The aim of this article focuses on analyzing the implications of fat-tailed distributions in emerging capital markets. An essential aspect that was highlighted by most empirical research, especially in terms of emerging capital markets, emphasizes the fact that extreme financial events can not be accurately predicted by the normal distribution. Fat-tailed distributions establish a very effective econometric tool in the analysis of rare events which are characterized by extreme values that occur with a relatively high frequency .The importance of exploring this particular issue derives from the fact that it is fundamental for optimal portfolio selection, derivatives valuation, financial hedging and risk management strategies. The implications of fat-tailed distributions for investment process are significant especially in the turbulent context of the global financial crisis.

  13. Arabidopsis poly(A) polymerase PAPS1 limits founder-cell recruitment to organ primordia and suppresses the salicylic acid-independent immune response downstream of EDS1/PAD4.

    Science.gov (United States)

    Trost, Gerda; Vi, Son Lang; Czesnick, Hjördis; Lange, Peggy; Holton, Nick; Giavalisco, Patrick; Zipfel, Cyril; Kappel, Christian; Lenhard, Michael

    2014-03-01

    Polyadenylation of pre-mRNAs by poly(A) polymerase (PAPS) is a critical process in eukaryotic gene expression. As found in vertebrates, plant genomes encode several isoforms of canonical nuclear PAPS enzymes. In Arabidopsis thaliana these isoforms are functionally specialized, with PAPS1 affecting both organ growth and immune response, at least in part by the preferential polyadenylation of subsets of pre-mRNAs. Here, we demonstrate that the opposite effects of PAPS1 on leaf and flower growth reflect the different identities of these organs, and identify a role for PAPS1 in the elusive connection between organ identity and growth patterns. The overgrowth of paps1 mutant petals is due to increased recruitment of founder cells into early organ primordia, and suggests that PAPS1 activity plays unique roles in influencing organ growth. By contrast, the leaf phenotype of paps1 mutants is dominated by a constitutive immune response that leads to increased resistance to the biotrophic oomycete Hyaloperonospora arabidopsidis and reflects activation of the salicylic acid-independent signalling pathway downstream of ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)/PHYTOALEXIN DEFICIENT4 (PAD4). These findings provide an insight into the developmental and physiological basis of the functional specialization amongst plant PAPS isoforms.

  14. Immunological evidence for the localization of a 110 kDa poly(A) binding protein from rat liver in nuclear envelopes and its phosphorylation by protein kinase C.

    Science.gov (United States)

    Schäfer, P; Aitken, S J; Bachmann, M; Agutter, P S; Müller, W E; Prochnow, D

    1993-11-01

    We have purified a 110 kDa poly(A) binding protein (P110) from rat liver which is thought to be involved in mRNA translocation through the nuclear pores and have demonstrated its localisation in the nuclear envelope using polyclonal antibodies and confocal laser scanning microscopy. Although P110 was prepared from highly purified nuclear envelopes, the polyclonal antibodies raised against them bind to nucleo- and cytoplasmic structures to a minor extent, but not to nucleolar structures. P110 decays spontaneously into several fragments which are also recognized by the polyclonal antibodies. The 110 kDa polypeptide and its fragments were phosphorylated by a nuclear envelope kinase and this phosphorylation was inhibited by a monoclonal antibody against protein kinase C and by a specific protein kinase C inhibitor obtained from bovine brain. Scatchard analysis was used to determine the influence of protein kinase C activators and inhibitors on nuclear envelope protein phosphorylation and RNA binding. The data indicate a close association between the RNA translocation machinery (the 110 kDa protein) and protein kinase C within the nuclear envelope. We suggest that the fragmentation of P110 is triggered before or during mRNA export and is not due to nonspecific proteolysis.

  15. Mechanism of c-erbB transduction: newly released transducing viruses retain poly(A) tracts of erbB transcripts and encode C-terminally intact erbB proteins.

    Science.gov (United States)

    Raines, M A; Maihle, N J; Moscovici, C; Crittenden, L; Kung, H J

    1988-01-01

    We have previously shown that avian leukosis virus (ALV) induces erythroblastosis by insertional activation of the c-erbB gene. In 25% of the ALV-induced leukemic samples we have analyzed, acute retroviruses that have captured the activated erbB oncogene were released. The unusually high frequency at which erbB transduction occurs makes this an ideal system for studying the mechanism of oncogene transduction. In addition, these leukemic samples provide a rich source for the isolation of novel erbB-transducing viruses. We report here our characterization of several new erbB-transducing proviruses. The 5' recombination points of all these viruses mapped to the same intron in which proviral insertions cluster, supporting the hypothesis that transduction begins with proviral insertion near the oncogene. The 3' recombination points usually occurred within the 3' untranslated region downstream from the termination codon of the c-erbB gene. Three of the erbB-containing proviruses were molecularly cloned and analyzed in detail. Two of them were capable of releasing acute viruses, and interestingly, both retained poly(A) tracts of erbB messages in their genomes. A stretch of six adenosine residues in the ALV env gene appeared to mediate the 3' recombination events required for the generation of these viruses. These data provide further insight into the mechanism by which oncogenes are transduced into retroviral genomes. Images PMID:2897475

  16. Spectral induced polarization (SIP) response of mine tailings.

    Science.gov (United States)

    Placencia-Gómez, Edmundo; Parviainen, Annika; Slater, Lee; Leveinen, Jussi

    2015-02-01

    Mine tailings impoundments are a source of leachates known as acid mine drainage (AMD) which can pose a contamination risk for surrounding surface and groundwater. Methodologies which can help management of this environmental issue are needed. We carried out a laboratory study of the spectral induced polarization (SIP) response of tailings from the Haveri Au-Cu mine, SW Finland. The primary objectives were, (1) to determine possible correlations between SIP parameters and textural properties associated with oxidative-weathering mechanisms, mineralogical composition and metallic content, and (2) to evaluate the effects of the pore water chemistry on SIP parameters associated with redox-inactive and redox-active electrolytes varying in molar concentration, conductivity and pH. The Haveri tailings exhibit well defined relaxation spectra between 100 and 10,000Hz. The relaxation magnitudes are governed by the in-situ oxidative-weathering conditions on sulphide mineral surfaces contained in the tailings, and decrease with the oxidation degree. The oxidation-driven textural variation in the tailings results in changes to the frequency peak of the phase angle, the imaginary conductivity and chargeability, when plotted versus the pore water conductivity. In contrast, the real and the formation electrical conductivity components show a single linear dependence on the pore water conductivity. The increase of the pore water conductivity (dominated by the increase of ions concentration in solution) along with a transition to acidic conditions shifts the polarization peak towards higher frequencies. These findings show the unique sensitivity of the SIP method to potentially discriminate AMD discharges from reactive oxidation zones in tailings, suggesting a significant advantage for monitoring threatened aquifers. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Grasping convergent evolution in syngnathids: a unique tale of tails.

    Science.gov (United States)

    Neutens, C; Adriaens, D; Christiaens, J; De Kegel, B; Dierick, M; Boistel, R; Van Hoorebeke, L

    2014-06-01

    Seahorses and pipehorses both possess a prehensile tail, a unique characteristic among teleost fishes, allowing them to grasp and hold onto substrates such as sea grasses. Although studies have focused on tail grasping, the pattern of evolutionary transformations that made this possible is poorly understood. Recent phylogenetic studies show that the prehensile tail evolved independently in different syngnathid lineages, including seahorses, Haliichthys taeniophorus and several types of so-called pipehorses. This study explores the pattern that characterizes this convergent evolution towards a prehensile tail, by comparing the caudal musculoskeletal organization, as well as passive bending capacities in pipefish (representing the ancestral state), pipehorse, seahorse and H. taeniophorus. To study the complex musculoskeletal morphology, histological sectioning, μCT-scanning and phase contrast synchrotron scanning were combined with virtual 3D-reconstructions. Results suggest that the independent evolution towards tail grasping in syngnathids reflects at least two quite different strategies in which the ancestral condition of a heavy plated and rigid system became modified into a highly flexible one. Intermediate skeletal morphologies (between the ancestral condition and seahorses) could be found in the pygmy pipehorses and H. taeniophorus, which are phylogenetically closely affiliated with seahorses. This study suggests that the characteristic parallel myoseptal organization as already described in seahorse (compared with a conical organization in pipefish and pipehorse) may not be a necessity for grasping, but represents an apomorphy for seahorses, as this pattern is not found in other syngnathid species possessing a prehensile tail. One could suggest that the functionality of grasping evolved before the specialized, parallel myoseptal organization seen in seahorses. However, as the grasping system in pipehorses is a totally different one, this cannot be

  18. Langmuir monolayers composed of single and double tail sulfobetaine lipids.

    Science.gov (United States)

    Hazell, Gavin; Gee, Anthony P; Arnold, Thomas; Edler, Karen J; Lewis, Simon E

    2016-07-15

    Owing to structural similarities between sulfobetaine lipids and phospholipids it should be possible to form stable Langmuir monolayers from long tail sulfobetaines. By modification of the density of lipid tail group (number of carbon chains) it should also be possible to modulate the two-dimensional phase behaviour of these lipids and thereby compare with that of equivalent phospholipids. Potentially this could enable the use of such lipids for the wide array of applications that currently use phospholipids. The benefit of using sulfobetaine lipids is that they can be synthesised by a one-step reaction from cheap and readily available starting materials and will degrade via different pathways than natural lipids. The molecular architecture of the lipid can be easily modified allowing the design of lipids for specific purposes. In addition the reversal of the charge within the sulfobetaine head group relative to the charge orientation in phospholipids may modify behaviour and thereby allow for novel uses of these surfactants. Stable Langmuir monolayers were formed composed of single and double tailed sulfobetaine lipids. Surface pressure-area isotherm, Brewster Angle Microscopy and X-ray and neutron reflectometry measurements were conducted to measure the two-dimensional phase behaviour and out-of-plane structure of the monolayers as a function of molecular area. Sulfobetaine lipids are able to form stable Langmuir monolayers with two dimensional phase behaviour analogous to that seen for the well-studied phospholipids. Changing the number of carbon tail groups on the lipid from one to two promotes the existence of a liquid condensed phase due to increased Van der Waals interactions between the tail groups. Thus the structure of the monolayers appears to be defined by the relative sizes of the head and tail groups in a predictable way. However, the presence of sub-phase ions has little effect on the monolayer structure, behaviour that is surprisingly different to

  19. Tailings dam-break flow - Analysis of sediment transport

    Science.gov (United States)

    Aleixo, Rui; Altinakar, Mustafa

    2015-04-01

    A common solution to store mining debris is to build tailings dams near the mining site. These dams are usually built with local materials such as mining debris and are more vulnerable than concrete dams (Rico et al. 2008). of The tailings and the pond water generally contain heavy metals and various toxic chemicals used in ore extraction. Thus, the release of tailings due to a dam-break can have severe ecological consequences in the environment. A tailings dam-break has many similarities with a common dam-break flow. It is highly transient and can be severely descructive. However, a significant difference is that the released sediment-water mixture will behave as a non-Newtonian flow. Existing numerical models used to simulate dam-break flows do not represent correctly the non-Newtonian behavior of tailings under a dam-break flow and may lead to unrealistic and incorrect results. The need for experiments to extract both qualitative and quantitative information regarding these flows is therefore real and actual. The present paper explores an existing experimental data base presented in Aleixo et al. (2014a,b) to further characterize the sediment transport under conditions of a severe transient flow and to extract quantitative information regarding sediment flow rate, sediment velocity, sediment-sediment interactions a among others. Different features of the flow are also described and analyzed in detail. The analysis is made by means of imaging techniques such as Particle Image Velocimetry and Particle Tracking Velocimetry that allow extracting not only the velocity field but the Lagrangian description of the sediments as well. An analysis of the results is presented and the limitations of the presented experimental approach are discussed. References Rico, M., Benito, G., Salgueiro, AR, Diez-Herrero, A. and Pereira, H.G. (2008) Reported tailings dam failures: A review of the European incidents in the worldwide context , Journal of Hazardous Materials, 152, 846

  20. Radiation hazard of solid metallic tailings in Shangluo, China

    OpenAIRE

    Zhuang Sukai; Lu Xinwei; Li Jiantao; Li Qian

    2016-01-01

    The radiation hazards of five kinds of different solid metallic tailings collected from Shangluo, China were determined on the basis of natural radioactivity measurements using low background multichannel gamma ray spectrometry. The activity concentration of 226Ra, 232Th and 40K in the tailings ranged from 5.1 to 204.3, 3.8 to 28.5, and 289.6 to 762.3 Bq/kg, respectively. The radium equivalent activities and the external hazard indexes of all studied metall...

  1. The effects of globotriaosylceramide tail saturation level on bilayer phases

    DEFF Research Database (Denmark)

    Pezeshkian, Weria; Chaban, Vitaly V; Johannes, Ludger

    2015-01-01

    of the Gb3 concentration and its acyl chain saturation on the phase behaviour of a mixed bilayer of dioleoylphosphatidylcholine and Gb3. The simulation results show that: (1) the Gb3 acyl chains (longer tails) from one leaflet interdigitate into the opposing leaflet and lead to significant bilayer...... rigidification and immobilisation of the lipid tails. S-Gb3 can form a highly ordered, relatively immobile phase which is resistant to bending while these changes for U-Gb3 are not significant. (2) At low concentrations of Gb3, U-Gb3 and S-Gb3 have a similar impact on the bilayer reminiscent of the effect...

  2. Adoption in rock and white-tailed ptarmigan

    Science.gov (United States)

    Wong, M.M.L.; Fedy, B.C.; Wilson, S.; Martin, K.M.

    2009-01-01

    Reports of adoption in birds are widespread, but few studies report rates of adoption or possible mechanisms for this phenomenon, particularly in the Order Galliformes. We report incidents of adoption in Rock Ptarmigan (Lagopus muta) and White-tailed Ptarmigan (L. leucura) from two sites in western Canada. Adoption rates for White-tailed Ptarmigan on Vancouver Island, British Columbia, and the Ruby Ranges, Yukon Territory were 13% (n = 16 broods) and 4% (n = 27), respectively, while rates for Rock Ptarmigan were 14% (n = 29) in the Ruby Ranges. Low brood densities may result in lower rates of adoption for ptarmigan. ?? 2009 The Wilson Ornithological Society.

  3. Disease Limits Populations: Plague and Black-Tailed Prairie Dogs

    OpenAIRE

    Cully, Jack F.; Johnson, Tammi L.; Collinge, Sharon K.; Ray, Chris

    2010-01-01

    Plague is an exotic vector-borne disease caused by the bacterium Yersinia pestis that causes mortality rates approaching 100% in black-tailed prairie dogs (Cynomys ludovicianus). We mapped the perimeter of the active portions of black-tailed prairie dog colonies annually between 1999 and 2005 at four prairie dog colony complexes in areas with a history of plague, as well as at two complexes that were located outside the distribution of plague at the time of mapping and had therefore never bee...

  4. Wake patterns of the wings and tail of hovering hummingbirds

    Science.gov (United States)

    Altshuler, Douglas L.; Princevac, Marko; Pan, Hansheng; Lozano, Jesse

    The flow fields of slowly flying bats and fasterflying birds differ in that bats produce two vortex loops during each stroke, one per wing, and birds produce a single vortex loop per stroke. In addition, the circulation at stroke transition approaches zero in bats but remains strong in birds. It is unknown if these difference derive from fundamental differences in wing morphology or are a consequence of flight speed. Here, we present an analysis of the horizontal flow field underneath hovering Anna's hummingbirds (Calypte anna) to describe the wake of a bird flying at zero forward velocity. We also consider how the hummingbird tail interacts with the wake generated by the wings. High-speed image recording and analysis from three orthogonal perspectives revealed that the wing tips reach peak velocities in the middle of each stroke and approach zero velocity at stroke transition. Hummingbirds use complex tail kinematic patterns ranging from in phase to antiphase cycling with respect to the wings, covering several phase shifted patterns. We employed particle image velocimetry to attain detailed horizontal flow measurements at three levels with respect to the tail: in the tail, at the tail tip, and just below the tail. The velocity patterns underneath the wings indicate that flow oscillates along the ventral-dorsal axis in response to the down- and up-strokes and that the sideways flows with respect to the bird are consistently from the lateral to medial. The region around the tail is dominated by axial flows in dorsal to ventral direction. We propose that these flows are generated by interaction between the wakes of the two wings at the end of the upstroke, and that the tail actively defects flows to generate moments that contribute to pitch stability. The flow fields images also revealed distinct vortex loops underneath each wing, which were generated during each stroke. From these data, we propose a model for the primary flow structures of hummingbirds that more

  5. Thin lift dewatering of oil sand tailings: optimizing dewatering of fluid fine tailings by controlling polymer mixing

    Energy Technology Data Exchange (ETDEWEB)

    Demoz, A.; Munoz, V.; Mikula, R. [Natural Resources Canada, CanmetENERGY, Devon, Alberta (Canada)

    2011-07-01

    In the oil sands industry, dewatering of tailings is an important issue. Recent work has shown that the addition of polymer helps to enhance dewatering of fluid fine tailings. High molecular weight polymers are used to bind small solids which results in a higher floc strength with no significant effect on water chemistry. The problem of this technique is that polymers only achieve optimal performance within a narrow window. This paper aimed at assessing the effect of mixing on the dewatering performance of polymer treatment on mature fine tailings. Tests were performed with different impeller types, mixing speeds and durations. Results demonstrated that the flocculation process is critical in the dewatering process and that working at the optimal flocculation conditions presents considerable benefits. This paper investigated the importance of mixing on the dewatering process and highlighted that further work has to be undertaken to optimize this process.

  6. Study on immobilization and migration of nuclide u in superficial soil of uranium tailings pond

    Science.gov (United States)

    Chang, Zhe; Zhou, Shukui

    2017-05-01

    The uranium tailings in southern China was used as the object of study to study the fixation and migration characteristics of nuclide U in shallow tailings. The results showed that the precipitation of tailings in the tailings soil was not linearly related to the depth during the acid rain leaching process. Tailings soil in the role of fixatives, when the lime as a fixative, the tailings of different soil uranium in 20 days after the re-precipitation. However, when lime and ammonium phosphate were used as fixing agents, the cumulative precipitation of U had a significant effect, and the migration of uranium was inhibited.

  7. Remote control canard missile with a free-rolling tail brake torque system

    Science.gov (United States)

    Blair, A. B., Jr.

    1981-01-01

    An experimental wind-tunnel investigation has been conducted at supersonic Mach numbers to determine the static aerodynamic characteristics of a cruciform canard-controlled missile with fixed and free-rolling tail-fin afterbodies. Mechanical coupling effects of the free-rolling tail afterbody were investigated using an electronic/electromagnetic brake system that provides arbitrary tail-fin brake torques with continuous measurements of tail-to-mainframe torque and tail-roll rate. Results are summarized to show the effects of fixed and free-rolling tail-fin afterbodies that include simulated measured bearing friction torques on the longitudinal and lateral-directional aerodynamic characteristics.

  8. The Influence of the Tailing Dump and Flotation Hydro - Tailing over the Environment in the Domestic Copper Mine

    OpenAIRE

    Krstev, Boris; Krstev, Aleksandar; Lazarov, Aleksandar; Danevski, Tome

    2012-01-01

    The presentation of the influence that the tailing dump or waste as well as the flotation hydro-tailing dump over the environment around the region of copper mine Bucim, surrounding rivers, places, villages and mine lake. Generally speaking, the monitoring will be done for two periods. The first analysis relating to the period from the year 2005, and the second analysis relating to the period from the year 2010. The monitoring with samples of waters, soil, sediments and ambient air as well as...

  9. The long X-ray tail in Zwicky 8338

    CERN Document Server

    Schellenberger, G

    2015-01-01

    The interaction processes in galaxy clusters between the hot ionized gas (ICM) and the member galaxies are of crucial importance in order to understand the dynamics in galaxy clusters, the chemical enrichment processes and the validity of their hydrostatic mass estimates. Recently, several X-ray tails associated to gas which was partly stripped of galaxies have been discovered. Here we report on the X-ray tail in the 3 keV galaxy cluster Zwicky 8338, which might be the longest ever observed. We derive the properties of the galaxy cluster environment and give hints on the substructure present in this X-ray tail, which is very likely associated to the galaxy CGCG254-021. The X-ray tail is extraordinarily luminous ($2\\times10^{42}$ erg/s), the thermal emission has a temperature of 0.8 keV and the X-ray luminous gas might be stripped off completely from the galaxy. From the assumptions on the 3D geometry we estimate the gas mass fraction (< 0.1%) and conclude that the gas has been compressed and/or heated.

  10. Right tail expansion of Tracy-Widom beta laws

    CERN Document Server

    Borot, Gaëtan

    2011-01-01

    Using loop equations, we compute the large deviation function of the maximum eigenvalue to the right of the spectrum in the Gaussian beta matrix ensembles, to all orders in 1/N. We then give a physical derivation of the all order asymptotic expansion of the right tail Tracy-Widom beta laws, for all positive beta, by studying the double scaling limit.

  11. Bias-corrected estimation of stable tail dependence function

    DEFF Research Database (Denmark)

    Beirlant, Jan; Escobar-Bach, Mikael; Goegebeur, Yuri

    2016-01-01

    We consider the estimation of the stable tail dependence function. We propose a bias-corrected estimator and we establish its asymptotic behaviour under suitable assumptions. The finite sample performance of the proposed estimator is evaluated by means of an extensive simulation study where...

  12. The utilization of forward osmosis for coal tailings dewatering

    Science.gov (United States)

    The feasibility of dewatering coal tailings slurry by forward osmosis (FO) membrane process was investigated in this research. A prototype cell was designed and used for the dewatering tests. A cellulosic FO membrane (Hydration Technology Innovations, LLC, Albany, OR) was used fo...

  13. [Morphogenetic changes during newt tail regeneration under changed gravity conditions].

    Science.gov (United States)

    Radugina, E A; Grigorian, É N

    2012-01-01

    Gravity-dependent shape alterations in newt tail regenerates are described, which were previously noticed in experiments onboard satellites Foton M2, M3 and in corresponding laboratory controls. Laboratory conditions were developed that allow reproducing this phenomenon persistently in the adult newts Pleurodeles waltl (Michahelles, 1830). The newts kept in an aquarium (in partial weightlessness) after 1/3 tail amputation developed normal lanceolate regenerates, while those that stayed on a moist mat (exposed to greater gravity than in aquarium) developed curved tail regenerates. Dynamics of the shape alterations were described using computer morphometric analysis. The curve was shown to develop at stage III of regeneration and to be caused by bending of the developing axial structures: the ependymal tube and the cartilage rode. Cellular processes were described that accompany the tail shape changes, such as cell migration and formation of dense aggregates. Unequal proliferation throughout the wound epidermis and blastema was revealed using BrdU assay. Proliferation increased within dorsal and apical regions of the regenerates in the newts kept on the mat cell compared with the aquarian animals.

  14. Bias-corrected estimation of stable tail dependence function

    DEFF Research Database (Denmark)

    Beirlant, Jan; Escobar-Bach, Mikael; Goegebeur, Yuri

    2016-01-01

    We consider the estimation of the stable tail dependence function. We propose a bias-corrected estimator and we establish its asymptotic behaviour under suitable assumptions. The finite sample performance of the proposed estimator is evaluated by means of an extensive simulation study where...

  15. Power-law cross-correlations estimation under heavy tails

    Science.gov (United States)

    Kristoufek, Ladislav

    2016-11-01

    We examine the performance of six estimators of the power-law cross-correlations-the detrended cross-correlation analysis, the detrending moving-average cross-correlation analysis, the height cross-correlation analysis, the averaged periodogram estimator, the cross-periodogram estimator and the local cross-Whittle estimator-under heavy-tailed distributions. The selection of estimators allows to separate these into the time and frequency domain estimators. By varying the characteristic exponent of the α-stable distributions which controls the tails behavior, we report several interesting findings. First, the frequency domain estimators are practically unaffected by heavy tails bias-wise. Second, the time domain estimators are upward biased for heavy tails but they have lower estimator variance than the other group for short series. Third, specific estimators are more appropriate depending on distributional properties and length of the analyzed series. In addition, we provide a discussion of implications of these results for empirical applications as well as theoretical explanations.

  16. North European short-tailed breeds of sheep: a review.

    Science.gov (United States)

    Dýrmundsson, O R; Niżnikowski, R

    2010-08-01

    The short-tailed sheep, native of an area stretching from Russia to Iceland, are generally considered a primitive type. These robust northern sheep seem to have been spread by Norse vikings to several countries in this area from the late eighth century to the middle of the eleventh century ad. They have several common characteristics in addition to the fluke-shaped and tapered short tail, such as a wide range of colour patterns, dual-coated wool and the ability to thrive under harsh environmental conditions, often in isolated marginal areas. While 34 short-tailed breeds of North European origin can still be identified, it is clear that their population sizes have declined in most cases and several of them are now rare and endangered. Although these breeds have mainly been confined to certain localities, some of them have gained considerable distribution due to their genetic merits, such as prolificacy. Of these, the Finnsheep and the Romanov are best known being exported to several countries in the world where their genetic material has been utilized through crossbreeding with local sheep. This has resulted in the production of some new synthetic breeds. Meat is now generally the main product of the North European short-tailed breeds and their crossbreds, whereas wool, skins and milk are normally regarded as byproducts, yet of considerable economic importance in some cases. Such breeds have clearly a role to play in sustainable grassland-based production systems in the future.

  17. measurement of radionuclides in processed mine tailings in jos ...

    African Journals Online (AJOL)

    DR. AMINU

    The Jos Plateau is situated in the central part of Northern Nigeria, on a rugged terrain of low lands ... A total of thirty-one (31) tailing samples were collected from a processing site in Jos at .... conventional units using the calibration factors from.

  18. Jump Tails, Extreme Dependencies, and the Distribution of Stock Returns

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Todorov, Viktor

    We provide a new framework for estimating the systematic and idiosyncratic jump tail risks in financial asset prices. The theory underlying our estimates are based on in-fill asymptotic arguments for directly identifying the systematic and idiosyncratic jumps, together with conventional long...

  19. The utilization of forward osmosis for coal tailings dewatering

    Science.gov (United States)

    The feasibility of dewatering coal tailings slurry by forward osmosis (FO) membrane process was investigated in this research. A prototype cell was designed and used for the dewatering tests. A cellulosic FO membrane (Hydration Technology Innovations, LLC, Albany, OR) was used fo...

  20. The Relationship between Infection and the Tailed IUD

    Institute of Scientific and Technical Information of China (English)

    金碧华; 吴裕浩; 潘仙花

    1997-01-01

    One hundred and eleven users of IUD were recruited and classified into two groups, 40 cases were in the tailed group, and 71 cases in the tailless group. The samples of each case were obtained from vaginal vault, the internal os of the cervix and uterine cavity. The cultures for detection of aerobic and anaerobic micro-organisms were indentified.The results indicated that 11 cases were of positive test in the internal os samples. Among them 8 cases were in the tailed group and 3 cases in the tailless group. There was a very significant difference (P < 0.01). 7 cases were found to be positive cultivation in the uterine cavity group among which 5 were in the tailed group and 2 in the tailless group. There was a significant difference (P < 0.05).It is noteworthy that the increased incidence of bacteria ascending from the internal os to the uterine cavity was found in the tailed group than that in the tailless group. However, severe pelvic inflammatory diseases in general have not been observed.

  1. Late time tail of wave propagation on curved spacetime

    CERN Document Server

    Ching, E S C; Suen, W M; Young, K; Ching, E S C; Leung, P T; Suen, W M; Young, K

    1994-01-01

    The late time behavior of waves propagating on a general curved spacetime is studied. The late time tail is not necessarily an inverse power of time. Our work extends, places in context, and provides understanding for the known results for the Schwarzschild spacetime. Analytic and numerical results are in excellent agreement.

  2. Muscle Responses to Stimulation of the Tadpole Tail

    Science.gov (United States)

    Funkhouser, Anne

    1976-01-01

    Describes use of tail muscles and spinal cord in the tadpole as an alternative source for muscle-and-nerve experiments. Includes explanation of simple dissection and preparation of tadpole; instructions for experiments such as threshold, strength of stimulus, frequency of stimulus, single twitch, tetanus, fatigue, effects of temperature on…

  3. Power tails of index distributions in chinese stock market

    Science.gov (United States)

    Zhang, J. W.; Zhang, Y.; Kleinert, H.

    2007-04-01

    The power α of the Lévy tails of stock market fluctuations discovered in recent years are generally believed to be universal. We show that for the Chinese stock market this is not true, the powers depending strongly on anomalous daily index changes short before market closure, and weakly on the opening data.

  4. Bounds for Tail Probabilities of the Sample Variance

    Directory of Open Access Journals (Sweden)

    V. Bentkus

    2009-01-01

    Full Text Available We provide bounds for tail probabilities of the sample variance. The bounds are expressed in terms of Hoeffding functions and are the sharpest known. They are designed having in mind applications in auditing as well as in processing data related to environment.

  5. Tail asymptotics for dependent subexponential differences

    DEFF Research Database (Denmark)

    Albrecher, H; Asmussen, Søren; Kortschak, D.

    We study the asymptotic behavior of P(X − Y > u) as u → ∞, where X is subexponential and X, Y are positive random variables that may be dependent. We give criteria under which the subtraction of Y does not change the tail behavior of X. It is also studied under which conditions the comonotonic co...

  6. Electrodialytic remediation of copper mine tailings using bipolar electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Rojo, Adrian, E-mail: adrian.rojo@usm.cl [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Cubillos, Luis [Departamento de Ingenieria Quimica y Ambiental, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile)

    2009-09-15

    In this work an electrodialytic remediation (EDR) cell for copper mine tailings with bipolar stainless steel plates was analyzed. The bipolar plates were inserted inside the tailings, dividing it into independent electrochemical cells or sections, in order to increase the copper removal efficiency from mine tailings. The bipolar plates design was tested on acidic copper mine tailings with a fixed: applied electric field, liquid content, initial pH, and remediation time. The laboratory results showed that inserting bipolar plates in EDR cells improves the remediation action, even though the applied electric field is reduced by the electrochemical reactions on the plates. Basically three aspects favor the process: reduction of the ionic migration pathways, increase of the electrode surface, and in-situ generation of protons (H{sup +}) and hydroxyls (OH{sup -}). Furthermore, the laboratory results with citric acid addition significantly improve the remediation actions, reaching copper removal of up to nine times better, compared to conventional EDR experiments without any plates or citric acid addition.

  7. Heavy Metal Accumulation in Plants on Mn Mine Tailings

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-Guo; ZHANG Hui-Zhi; ZENG Guang-Ming; HUANG Bao-Rong; LI Xin

    2006-01-01

    The Xiangtan Manganese (Mn) Mine in the middle of Hunan Province, China, has been mined since 1913 with mine tailings including excavated wastes, wastewater, and smelting wastes. A survey was conducted on the Mn mine tailing soils and eight plants on the Mn mine tailings. The concentrations of soil Mn, Pb, and Cd and the metal-enrichment traits of these eight plants were analyzed simultaneously. Exceptionally high concentrations of these three metals were found in the soils, especially on the tailing dam. Each plant investigated in this study accumulated the three heavy metals, but no hyperaccumulator of these metals was found. However, analysis indicated that Poa pratensis Linn., Gnaphalium affine D. Don, Pteris vittata L., CoRyza canadensis (L.) Cronq., and Phytolacca acinosa Roxb. possessed specially good metalenrichment and metal-tolerant traits. P. pratensis, G. affine, and P. vittata were Pb-tolerant plants; and C. canadensis,P. pratensis, and G. affine were Cd-tolerant plants. P. acinosa had a great tolerance to Mn, and it was a valuable plant for on-site phytoremediation. Phragmites communis Trin. was found to have high metal tolerance and economic benefit as a raw material for paper and should be considered for soil remediation. G. affine and C. canadensis had excessive accumulation of Mn and could be useful in phytoremediation. However, although P. pratensis was a good accumulator,it was not a suitable plant for soil remediation because its biomass was too little.

  8. Cross-tail current evolution during substorm dipolarization

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2013-06-01

    Full Text Available We examine evolution of the cross-tail current during substorm current disruption/dipolarization using observations from two satellites in the near-Earth magnetotail at the downtail distances of 8–9 RE. By choosing times when these two satellites are separated, mainly in the north–south distance in the tail current sheet, precise determination of current density in the layer embedded between these satellites can be obtained with Ampère's law. Two such events are examined and several common features are found. The current densities in the layer embedded by the two satellites were reduced by ~ 40–70% during substorm dipolarization. The changes in current densities have the fast kinetic timescale, i.e., in seconds, implying a kinetic process for current disruption/dipolarization. The estimated power within the current layer was mainly dissipative in the dawn–dusk direction and mainly dynamo in the Sun–tail direction that is needed to drive the north–south substorm current system in the ionosphere. Remote sensing of the energization site with the ion sounding technique shows that the energization site was initially earthward of the satellite and moved down the tail at later times. Breakdown of the frozen-in condition occurred intermittently during the disturbance interval. These features provide important clues to the substorm onset process.

  9. Long memory and tail dependence in trading volume and volatility

    DEFF Research Database (Denmark)

    Rossi, Eduardo; Santucci de Magistris, Paolo

    2013-01-01

    We investigate the relationship between volatility, measured by realized volatility, and trading volume for 25 NYSE stocks. We show that volume and volatility are long memory but not fractionally cointegrated in most cases. We also find right tail dependence in the volatility and volume innovations...

  10. Trace elements contamination of soils around gold mine tailings ...

    African Journals Online (AJOL)

    ISHIOMA

    Average concentrations of As, Cu, Pb and Zn in soils around the active tailings ... regarding presence of trace elements in water sources, soils and foodstuffs at .... in the Obuasi region is reportedly among the highest in the world, and has been.

  11. TAIL INDEX ESTIMATION FOR A FILTERED DEPENDENT TIME SERIES

    National Research Council Canada - National Science Library

    Jonathan B. Hill

    2015-01-01

    We prove Hill's (1975) tail index estimator is asymptotically normal when the employed data are generated by a stationary parametric time series (xt(θ0) : t ∈ ℤ} and θ0 is an unknown k × 1 vector. We assume xt(θ0...

  12. Spinal cord regeneration in a tail autotomizing urodele.

    Science.gov (United States)

    Dawley, Ellen M; O Samson, Shoji; Woodard, Kenton T; Matthias, Kathryn A

    2012-02-01

    Adult urodele amphibians possess extensive regenerative abilities, including lens, jaws, limbs, and tails. In this study, we examined the cellular events and time course of spinal cord regeneration in a species, Plethodon cinereus, that has the ability to autotomize its tail as an antipredator strategy. We propose that this species may have enhanced regenerative abilities as further coadaptations with this antipredator strategy. We examined the expression of nestin, vimentin, and glial fibrillary acidic protein (GFAP) after autotomy as markers of neural precursor cells and astroglia; we also traced the appearance of new neurons using 5-bromo-2'-deoxyuridine/neuronal nuclei (BrdU/NeuN) double labeling. As expected, the regenerating ependymal tube was a major source of new neurons; however, the spinal cord cranial to the plane of autotomy showed significant mitotic activity, more extensive than what is reported for other urodeles that cannot autotomize their tails. In addition, this species shows upregulation of nestin, vimentin, and GFAP within days after tail autotomy; further, this expression is upregulated within the spinal cord cranial to the plane of autotomy, not just within the extending ependymal tube, as reported in other urodeles. We suggest that enhanced survival of the spinal cord cranial to autotomy allows this portion to participate in the enhanced recovery and regeneration of the spinal cord. Copyright © 2011 Wiley Periodicals, Inc.

  13. Computational modelling of final covers for uranium mill tailings impoundments.

    Science.gov (United States)

    Leoni, Guilherme Luís Menegassi; Almeida, Márcio de Souza Soares; Fernandes, Horst Monken

    2004-07-05

    To properly design a final cover for uranium mill tailings impoundments the designer must attempt to find an effective geotechnical solution which addresses the radiological and non-radiological potential impact and prevents geochemical processes from occurring within the tailings. This paper presents a computer-based method for evaluating the performance of engineered final covers for the remediation of uranium mill tailings impoundments. Three hypothetical final covers were taken from scientific literature to investigate the proposed method: (i) a compacted clay liner (CCL); (ii) a composite liner (CL) and (iii) a capillary barrier (CB). The processes investigated: (i) the saturated hydraulic flux; (ii) the unsaturated hydraulic flux (exclusively for the capillary barrier) and (iii) the radon exhalation to the atmosphere. The computer programs utilised for the analyses are: (i) Hydrologic Evaluation of Landfill Performance (HELP); (ii) SEEP/W and (iii) RADON. The site considered for the development of the research presented herein was the uranium mill tailings impoundment located at the Brazilian city of Poços de Caldas, in the Minas Gerais State.

  14. Head-Tail Modes for Strong Space Charge

    Energy Technology Data Exchange (ETDEWEB)

    Burov, Alexey

    2008-12-01

    Head-tail modes are described here for the space charge tune shift significantly exceeding the synchrotron tune. General equation for the modes is derived. Spatial shapes of the modes, their frequencies, and coherent growth rates are explored. The Landau damping rates are also found. Suppression of the transverse mode coupling instability by the space charge is explained.

  15. Long memory and tail dependence in trading volume and volatility

    DEFF Research Database (Denmark)

    Rossi, Eduardo; Santucci de Magistris, Paolo

    2013-01-01

    We investigate the relationship between volatility, measured by realized volatility, and trading volume for 25 NYSE stocks. We show that volume and volatility are long memory but not fractionally cointegrated in most cases. We also find right tail dependence in the volatility and volume innovations...

  16. Runaway Events Dominate the Heavy Tail of Citation Distributions

    CERN Document Server

    Golosovsky, Michael

    2013-01-01

    Statistical distributions with heavy tails are ubiquitous in natural and social phenomena. Since the entries in heavy tail have disproportional significance, the knowledge of its exact shape is very important. Citations of scientific papers form one of the best-known heavy tail distributions. Even in this case there is a considerable debate whether citation distribution follows the log-normal or power-law fit. The goal of our study is to solve this debate by measuring citation distribution for a very large and homogeneous data. We measured citation distribution for 418,438 Physics papers published in 1980-1989 and cited by 2008. While the log-normal fit deviates too strong from the data, the discrete power-law function with the exponent $\\gamma=3.15$ does better and fits 99.955% of the data. However, the extreme tail of the distribution deviates upward even from the power-law fit and exhibits a dramatic "runaway" behavior. The onset of the runaway regime is revealed macroscopically as the paper garners 1000-1...

  17. Element flows associated with marine shore mine tailings deposits.

    Science.gov (United States)

    Dold, Bernhard

    2006-02-01

    From 1938 until 1975, flotation tailings from the Potrerillos--El Salvador mining district (porphyry copper deposits) were discharged into the El Salado valley and transported in suspension to the sea at Chaliaral Bay, Atacama Desert, northern Chile. Over 220 Mt of tailings, averaging 0.8 +/- 0.25 wt % of pyrite, were deposited into the bay, resulting in over a 1 kilometer seaward displacement of the shoreline and an estimated 10-15 m thick tailings accumulation covering a approximately 4 km2 surface area. The Chaniaral case was classified by the United Nations Environmental Programme (UNEP) in 1983 as one of the most serious cases of marine contamination in the Pacific area. Since 1975, the tailings have been exposed to oxidation, resulting in a 70-188 cm thick low-pH (2.6-4) oxidation zone at the top with liberation of divalent metal cations, such as Cu2+, Ni2+, and Zn2+ (up to 2265 mg/L, 18.1 mg/L, and 20.3 mg/ L, respectively). Evaporation-induced transport capillarity led to metal enrichment atthe tailings surface (e.g. up to 2.4% Cu) in the form of secondary chlorides and/or sulfates (dominated by eriochalcite [CuCl.H2O] and halite). These, mainly water-soluble, secondary minerals were exposed to eolian transport in the direction of the Village of Chañaral by the predominant W-SW winds. Two element-flow directions (toward the tailings surface, via capillarity, and toward the sea) and two element groups with different geochemical behaviors (cations such as Cu, Zn, Ni, and oxyanions such as As and Mo) could be distinguished. It can be postulated, that the sea is mainly affected by the following: As, Mo, Cu, and Zn contamination, which were liberated from the oxidation zone from the tailings and mobilized through the tidal cycle, and by Cu and Zn from the subsurface waters flowing in the El Salado valley (up to 19 mg/L and 12 mg/L Zn, respectively), transported as chloro complexes at neutral pH.

  18. Emergent Data-Networks from Long-Tail Collections

    Science.gov (United States)

    Elag, M.; Kumar, P.; Marini, L.; Hedstrom, M.; Myers, J. D.; Plale, B. A.

    2014-12-01

    Synthesis of scientific data coming from individuals and small research group activities, known as long-tail data, with the existing resources elucidates useful scientific knowledge. In general, long-tail data are irreplaceable, expensive to reproduce, infrequently reused, follow no predefined data model, and they are often bounded in different information systems. The contextual relationships across the many attributes among such data in a data collection are herewith defined as data-network. These relationships have the potential to provide deep insights for the scientific challenges that require multidisciplinary interaction by identifying a new data object in the broader context of other data objects, and characterizing its spatial and temporal dependencies with others. Despite the advancement that has been achieved in various geoscience information models, it is not always straightforward to identify and characterize the contextual relationships among long-tail data because information models focus on profiling data attributes more than exploring data tie-ins. To address this need, we have designed the Long Tail Data Networks (LTDN) engine, which depends on a context-based approach to analyze the data attributes, predict data contextual relationships, and publish these relationships as a RDF graph. The engine groups data using their geographic location in spatial collections, and applies binary logic predicates to analyze the spatial, temporal, and variable attributes associated with data entities of each spatial collection to infer their relationships. Here we present the design of the LTDN engine and demonstrate its application for predicting the latent connectivity among long-tail data collections. To demonstrate the capabilities of the engine, we implemented this approach within the Sustainable Environment Actionable Data (SEAD) environment, an open-source semantic content repository that supports long-tail data curation and preservation, and show how

  19. Plant and soil reactions to nickel ore processed tailings

    Energy Technology Data Exchange (ETDEWEB)

    Sheets, P.J.; Volk, V.V.; Gardner, E.H.

    1982-07-01

    Greenhouse and laboratory experiments were conducted to determine the effect that tailings, produced during the processing of nickeliferous laterite ores by a proposed U.S. Bureau of Mines Process, would have on plant growth and soil properties. The tailings contained soluble salts (7.6 mmhos/cm), NH/sub 4/-N (877 ..mu..g/g), Ni (0.28%), Mn (82 ..mu..g/g DTPA-extractable), Cr (0.44%), P (2 and 6 ..mu..g/g acid F- and NaHCO/sub 3/-extractable, respectively), and Ca and Mg (1.0 and 20.7 meq/100 g NH/sub 4/Ac-extractable, respectively). Water leaching decreased the NH/sub 4/-N concentration to 53 ..mu..g/g and the EC to 0.4 mmhos/cm by removal of (NH/sub 4/)/sub 2/SO/sub 4/ and MgSO/sub 4/ salts. Tall fescue (Festuca arundinacea Schreb.) was grown on Eightlar clay soil (skeletal, serpentinitic, mesic Typic Xerochrept) amended with 0, 223, 446, and 669 g tailings/kg soil and pure, unleached tailings for 32 weeks in the greenhouse. Seedling establishment of plants grown on soil amended at the highest tailings rate and the pure tailings was initially slow, but plants grown on soil amended at lower rates established readily and grew well. Plant P was <0.24%, while plant Ca concentrations were <0.45% throughout the growth period even though Ca(H/sub 2/PO/sub 2/)/sub 2/ and gypsum had been added. Ammonium acetate-extractable Ca at the end of the growth period was <5.0 meq/100 g on all amended soils.The Mn, Ni, and Cr concentrations of plants grown on treated soils were within normal ranges, although soil-analysis values were higher than commonly found. It is recommended that the tailings be washed to reduce NH/sub 4/-N and soluble salts prior to revegetation, and that native soil be added to the surface to reduce crusting.

  20. Evaluation of common anesthetic and analgesic techniques for tail biopsy in mice.

    Science.gov (United States)

    Jones, Carissa P; Carver, Scott; Kendall, Lon V

    2012-11-01

    Tail biopsy in mice is a common procedure in genetically modified mouse colonies. We evaluated the anesthetic and analgesic effects of various agents commonly used to mitigate pain after tail biopsy. We used a hot-water immersion assay to evaluate the analgesic effects of isoflurane, ice-cold ethanol, ethyl chloride, buprenorphine, and 2-point local nerve blocks before studying their effects on mice receiving tail biopsies. Mice treated with ethyl chloride spray, isoflurane and buprenorphine, and 2-point local nerve blocks demonstrated increased tail-flick latency compared with that of untreated mice. When we evaluated the behavior of adult and preweanling mice after tail biopsy, untreated mice demonstrated behavioral changes immediately after tail biopsy that lasted 30 to 60 min before returning to normal. The use of isoflurane, isoflurane and buprenorphine, buprenorphine, 2-point nerve block, or ethyl chloride spray in adult mice did not significantly improve their behavioral response to tail biopsy. Similarly, the use of buprenorphine and ethyl chloride spray in preweanling mice did not improve their behavioral response to tail biopsy compared with that of the untreated group. However, immersion in bupivacaine for 30 s after tail biopsy decreased tail grooming behavior during the first 30 min after tail biopsy. The anesthetic and analgesic regimens tested provide little benefit in adult and preweanling mice. Given that tail biopsy results in pain that lasts 30 to 60 min, investigators should carefully consider the appropriate anesthetic or analgesic regimen to incorporate into tail-biopsy procedures for mice.