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Sample records for selex systematic evolution

  1. Integrated microfluidic system for rapid screening of CRP aptamers utilizing systematic evolution of ligands by exponential enrichment (SELEX).

    Science.gov (United States)

    Huang, Chao-June; Lin, Hsin-I; Shiesh, Shu-Chu; Lee, Gwo-Bin

    2010-03-15

    The systematic evolution of ligands by exponential enrichment (SELEX) is an experimental procedure that allows screening of given molecular targets by desired binding affinities from an initial random pool of oligonucleotides and oligomers. The final products of SELEX are usually referred as aptamers, which are recognized as promising molecules for a variety of biomedical applications. However, SELEX is an iterative process requiring multiple rounds of extraction and amplification that demands significant time and labor. Therefore, this study presents a novel, automatic, miniature SELEX platform. As a demonstration, the rapid screening of C-reactive protein (CRP) aptamers was performed. By utilizing microfluidic technologies and magnetic beads conjugated with CRP, aptamers with a high affinity to CRP were extracted from a random single-strand deoxyribonucleic acid (ssDNA) pool. These aptamers were further amplified by an on-chip polymerase chain reaction (PCR) process. After five consecutive extraction and amplification cycles, a specific aptamer with the highest affinity was screened automatically. The screened aptamers were used as a recognition molecule for the detection of CRP. The developed microsystem demonstrated fast screening of CRP aptamers and can be used as a powerful tool to select analyte-specific aptamers for biomedical applications. (c) 2009 Elsevier B.V. All rights reserved.

  2. CELL-SELEX: Novel Perspectives of Aptamer-Based Therapeutics

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    Hans P. Wendel

    2008-04-01

    Full Text Available Aptamers, single stranded DNA or RNA molecules, generated by a method called SELEX (systematic evolution of ligands by exponential enrichment have been widely used in various biomedical applications. The newly developed Cell-SELEX (cell based-SELEX targeting whole living cells has raised great expectations for cancer biology, -therapy and regenerative medicine. Combining nanobiotechnology with aptamers, this technology opens the way to more sophisticated applications in molecular diagnosis. This paper gives a review of recent developments in SELEX technologies and new applications of aptamers.

  3. Development of Cell-SELEX Technology and Its Application in Cancer Diagnosis and Therapy

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    Chen, Man; Yu, Yuanyuan; Jiang, Feng; Zhou, Junwei; Li, Yongshu; Liang, Chao; Dang, Lei; Lu, Aiping; Zhang, Ge

    2016-01-01

    SELEX (systematic evolution of ligands by exponential enrichment) is a process involving the progressive isolation of high selective ssDNA/RNA from a combinatorial single-stranded oligonucleotide library through repeated rounds of binding, partitioning and amplification. SELEX-derived single-stranded DNA/RNA molecules, called aptamers, are selected against a wide range of targets, including purified proteins, live cells, tissues, microorganisms, small molecules and so on. With the development of SELEX technology over the last two decades, various modified SELEX processes have been arisen. A majority of aptamers are selected against purified proteins through traditional SELEX. Unfortunately, more and more evidence showed aptamers selected against purified membrane proteins failed to recognize their targets in live cells. Cell-SELEX could develop aptamers against a particular target cell line to discriminate this cell line from others. Therefore, cell-SELEX has been widely used to select aptamers for the application of both diagnosis and therapy of various diseases, especially for cancer. In this review, the advantages and limitations of cell-SELEX and SELEX against purified protein will be compared. Various modified cell-SELEX techniques will be summarized, and application of cell-SELEX in cancer diagnosis and therapy will be discussed. PMID:27973403

  4. Generating Aptamers by Cell-SELEX for Applications in Molecular Medicine

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    Huixia Liu

    2012-03-01

    Full Text Available Aptamers are single-stranded oligonucleotides of DNA or RNA that bind to target molecules with high affinity and specificity. Typically, aptamers are generated by an iterative selection process, called systematic evolution of ligands by exponential enrichment (SELEX. Recent advancements in SELEX technology have extended aptamer selection from comparatively simple mixtures of purified proteins to whole living cells, and now cell-based SELEX (or cell-SELEX can isolate aptamers that bind to specific target cells. Combined with nanotechnology, microchips, microfluidic devices, RNAi and other advanced technologies, cell-SELEX represents an integrated platform providing ultrasensitive and highly specific tools for clinical medicine. In this review, we describe the recent progress made in the application of cell-SELEX for diagnosis, therapy and biomarker discovery.

  5. Systematic search for the Cra-binding promoters using genomic SELEX system.

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    Shimada, Tomohiro; Fujita, Nobuyuki; Maeda, Michihisa; Ishihama, Akira

    2005-09-01

    Cra (or FruR), a global transcription factor with both repression and activation activities, controls a large number of the genes for glycolysis and gluconeogenesis. To get insights into the entire network of transcription regulation of the E. coli genome by Cra, we isolated a set of Cra-binding sequences using an improved method of genomic SELEX. From the DNA sequences of 97 independently isolated DNA fragments by SELEX, the Cra-binding sequences were identified in a total of ten regions on the E. coli genome, including promoters of six known genes and four hitherto-unidentified genes. All six known promoters are repressed by Cra, but none of the activation-type promoters were cloned after two cyles of SELEX, because the Cra-binding affinity to the repression-type promoters is higher than the activation-type promoters, as determined by the quantitative gel shift assay. Of a total of four newly identified Cra-binding sequences, two are associated with promoter regions of the gapA (glyceraldehyde 3-phosphate dehydrogenase) and eno (enolase) genes, both involved in sugar metabolism. The regulation of newly identified genes by Cra was confirmed by the in vivo promoter strength assay using a newly developed TFP (two-fluorescent protein) vector for promoter assay or by in vitro transcription assay in the presence of Cra protein.

  6. Performing SELEX experiments in silico

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    Wondergem, J. A. J.; Schiessel, H.; Tompitak, M.

    2017-11-01

    Due to the sequence-dependent nature of the elasticity of DNA, many protein-DNA complexes and other systems in which DNA molecules must be deformed have preferences for the type of DNA sequence they interact with. SELEX (Systematic Evolution of Ligands by EXponential enrichment) experiments and similar sequence selection experiments have been used extensively to examine the (indirect readout) sequence preferences of, e.g., nucleosomes (protein spools around which DNA is wound for compactification) and DNA rings. We show how recently developed computational and theoretical tools can be used to emulate such experiments in silico. Opening up this possibility comes with several benefits. First, it allows us a better understanding of our models and systems, specifically about the roles played by the simulation temperature and the selection pressure on the sequences. Second, it allows us to compare the predictions made by the model of choice with experimental results. We find agreement on important features between predictions of the rigid base-pair model and experimental results for DNA rings and interesting differences that point out open questions in the field. Finally, our simulations allow application of the SELEX methodology to systems that are experimentally difficult to realize because they come with high energetic costs and are therefore unlikely to form spontaneously, such as very short or overwound DNA rings.

  7. SELEX-Based Screening of Exosome-Tropic RNA.

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    Yamashita, Takuma; Shinotsuka, Haruka; Takahashi, Yuki; Kato, Kana; Nishikawa, Makiya; Takakura, Yoshinobu

    2017-01-01

    Cell-derived nanosized vesicles or exosomes are expected to become delivery carriers for functional RNAs, such as small interfering RNA (siRNA). A method to efficiently load functional RNAs into exosomes is required for the development of exosome-based delivery carriers of functional RNAs. However, there is no method to find exosome-tropic exogenous RNA sequences. In this study, we used a systematic evolution of ligands by exponential enrichment (SELEX) method to screen exosome-tropic RNAs that can be used to load functional RNAs into exosomes by conjugation. Pooled single stranded 80-base RNAs, each of which contains a randomized 40-base sequence, were transfected into B16-BL6 murine melanoma cells and exosomes were collected from the cells. RNAs extracted from the exosomes were subjected to next round of SELEX. Cloning and sequencing of RNAs in SELEX-screened RNA pools showed that 29 of 56 clones had a typical RNA sequence. The sequence found by SELEX was enriched in exosomes after transfection to B16-BL6 cells. The results show that the SELEX-based method can be used for screening of exosome-tropic RNAs.

  8. Refining the Results of a Classical SELEX Experiment by Expanding the Sequence Data Set of an Aptamer Pool Selected for Protein A

    OpenAIRE

    Regina Stoltenburg; Beate Strehlitz

    2018-01-01

    New, as yet undiscovered aptamers for Protein A were identified by applying next generation sequencing (NGS) to a previously selected aptamer pool. This pool was obtained in a classical SELEX (Systematic Evolution of Ligands by EXponential enrichment) experiment using the FluMag-SELEX procedure followed by cloning and Sanger sequencing. PA#2/8 was identified as the only Protein A-binding aptamer from the Sanger sequence pool, and was shown to be able to bind intact cells of Staphylococcus aur...

  9. Development of a fraction collection approach in capillary electrophoresis SELEX for aptamer selection.

    Science.gov (United States)

    Luo, Zhaofeng; Zhou, Hongmin; Jiang, Hao; Ou, Huichao; Li, Xin; Zhang, Liyun

    2015-04-21

    Aptamers have attracted much attention due to their ability to bind to target molecules with high affinity and specificity. The development of an approach capable of efficiently generating aptamers through systematic evolution of ligands by exponential enrichment (SELEX) is particularly challenging. Herein, a fraction collection approach in capillary electrophoresis SELEX (FCE-SELEX) for the partition of a bound DNA-target complex is developed. By integrating fraction collection with a facile oil seal method for avoiding contamination while amplifying the bound DNA-target complex, in a single round of selection, a streptavidin-binding aptamer (SBA) has been generated. The affinity of aptamer SBA-36 for streptavidin (SA) is determined as 30.8 nM by surface plasmon resonance (SPR). Selectivity and biotin competition experiments demonstrate that the SBA-36 aptamer selected by FCE-SELEX is as efficient as those from other methods. Based on the ability of fraction collection in partition and collection of the aptamer-target complex from the original DNA library, FCE-SELEX can be a universal tool for the development of aptamers.

  10. A mathematical analysis of multiple-target SELEX.

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    Seo, Yeon-Jung; Chen, Shiliang; Nilsen-Hamilton, Marit; Levine, Howard A

    2010-10-01

    SELEX (Systematic Evolution of Ligands by Exponential Enrichment) is a procedure by which a mixture of nucleic acids can be fractionated with the goal of identifying those with specific biochemical activities. One combines the mixture with a specific target molecule and then separates the target-NA complex from the resulting reactions. The target-NA complex is separated from the unbound NA by mechanical means (such as by filtration), the NA is eluted from the complex, amplified by PCR (polymerase chain reaction), and the process repeated. After several rounds, one should be left with the nucleic acids that best bind to the target. The problem was first formulated mathematically in Irvine et al. (J. Mol. Biol. 222:739-761, 1991). In Levine and Nilsen-Hamilton (Comput. Biol. Chem. 31:11-25, 2007), a mathematical analysis of the process was given. In Vant-Hull et al. (J. Mol. Biol. 278:579-597, 1998), multiple target SELEX was considered. It was assumed that each target has a single nucleic acid binding site that permits occupation by no more than one nucleic acid. Here, we revisit Vant-Hull et al. (J. Mol. Biol. 278:579-597, 1998) using the same assumptions. The iteration scheme is shown to be convergent and a simplified algorithm is given. Our interest here is in the behavior of the multiple target SELEX process as a discrete "time" dynamical system. Our goal is to characterize the limiting states and their dependence on the initial distribution of nucleic acid and target fraction components. (In multiple target SELEX, we vary the target component fractions, but not their concentrations, as fixed and the initial pool of nucleic acids as a variable starting condition). Given N nucleic acids and a target consisting of M subtarget component species, there is an M × N matrix of affinities, the (i,j) entry corresponding to the affinity of the jth nucleic acid for the ith subtarget. We give a structure condition on this matrix that is equivalent to the following

  11. An Evolutionary/Biochemical Connection Between Promoter- and Primer-Dependent Polymerases Revealed by Selective Evolution of Ligands by Exponential Enrichment (SELEX).

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    Fenstermacher, Katherine J; Achuthan, Vasudevan; Schneider, Thomas D; DeStefano, Jeffrey J

    2018-01-16

    DNA polymerases (DNAPs) recognize 3' recessed termini on duplex DNA and carry out nucleotide catalysis. Unlike promoter-specific RNA polymerases (RNAPs), no sequence specificity is required for binding or initiation of catalysis. Despite this, previous results indicate that viral reverse transcriptases bind much more tightly to DNA primers that mimic the polypurine tract. In the current report, primer sequences that bind with high affinity to Taq and Klenow polymerases were identified using a modified Selective Evolution of Ligands by Exponential Enrichment (SELEX) approach. Two Taq -specific primers that bound ∼10 (Taq1) and over 100 (Taq2) times more stably than controls to Taq were identified. Taq1 contained 8 nucleotides (5' -CACTAAAG-3') that matched the phage T3 RNAP "core" promoter. Both primers dramatically outcompeted primers with similar binding thermodynamics in PCR reactions. Similarly, exonuclease minus Klenow polymerase also selected a high affinity primer that contained a related core promoter sequence from phage T7 RNAP (5' -ACTATAG-3'). For both Taq and Klenow, even small modifications to the sequence resulted in large losses in binding affinity suggesting that binding was highly sequence-specific. The results are discussed in the context of possible effects on multi-primer (multiplex) PCR assays, molecular information theory, and the evolution of RNAPs and DNAPs. Importance This work further demonstrates that primer-dependent DNA polymerases can have strong sequence biases leading to dramatically tighter binding to specific sequences. These may be related to biological function, or be a consequences of the structural architecture of the enzyme. New sequence specificity for Taq and Klenow polymerases were uncovered and among them were sequences that contained the core promoter elements from T3 and T7 phage RNA polymerase promoters. This suggests the intriguing possibility that phage RNA polymerases exploited intrinsic binding affinities of

  12. New Technologies Provide Quantum Changes in the Scale, Speed, and Success of SELEX Methods and Aptamer Characterization

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    Abdullah Ozer

    2014-01-01

    Full Text Available Single-stranded oligonucleotide aptamers have attracted great attention in the past decade because of their diagnostic and therapeutic potential. These versatile, high affinity and specificity reagents are selected by an iterative in vitro process called SELEX, Systematic Evolution of Ligands by Exponential Enrichment. Numerous SELEX methods have been developed for aptamer selections; some that are simple and straightforward, and some that are specialized and complicated. The method of SELEX is crucial for selection of an aptamer with desired properties; however, success also depends on the starting aptamer library, the target molecule, aptamer enrichment monitoring assays, and finally, the analysis and characterization of selected aptamers. Here, we summarize key recent developments in aptamer selection methods, as well as other aspects of aptamer selection that have significant impact on the outcome. We discuss potential pitfalls and limitations in the selection process with an eye to aid researchers in the choice of a proper SELEX strategy, and we highlight areas where further developments and improvements are desired. We believe carefully designed multiplexed selection methods, when complemented with high-throughput downstream analysis and characterization assays, will yield numerous high-affinity aptamers to protein and small molecule targets, and thereby generate a vast array of reagents for probing basic biological mechanisms and implementing new diagnostic and therapeutic applications in the near future.

  13. Selection of aptamers specific for glycated hemoglobin and total hemoglobin using on-chip SELEX.

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    Lin, Hsin-I; Wu, Ching-Chu; Yang, Ching-Hsuan; Chang, Ko-Wei; Lee, Gwo-Bin; Shiesh, Shu-Chu

    2015-01-21

    Blood glycated hemoglobin (HbA1c) levels reflecting average glucose concentrations over the past three months are fundamental for the diagnosis, monitoring, and risk assessment of diabetes. It has been hypothesized that aptamers, which are single-stranded DNAs or RNAs that demonstrate high affinity to a large variety of molecules ranging from small drugs, metabolites, or proteins, could be used for the measurement of HbA1c. Aptamers are selected through an in vitro process called systematic evolution of ligands by exponential enrichment (SELEX), and they can be chemically synthesized with high reproducibility at relatively low costs. This study therefore aimed to select HbA1c- and hemoglobin (Hb)-specific single-stranded DNA aptamers using an on-chip SELEX protocol. A microfluidic SELEX chip was developed to continuously and automatically carry out multiple rounds of SELEX to screen specific aptamers for HbA1c and Hb. HbA1c and Hb were first coated onto magnetic beads. Following several rounds of selection and enrichment with a randomized 40-mer DNA library, specific oligonucleotides were selected. The binding specificity and affinity were assessed by competitive and binding assays. Using the developed microfluidic system, the incubation and partitioning times were greatly decreased, and the entire process was shortened dramatically. Both HbA1c- and Hb-specific aptamers selected by the microfluidic system showed high specificity and affinity (dissociation constant, Kd = 7.6 ± 3.0 nM and 7.3 ± 2.2 nM for HbA1c and Hb, respectively). With further refinements in the assay, these aptamers may replace the conventional antibodies for in vitro diagnostics applications in the near future.

  14. Comparison of Whole-Cell SELEX Methods for the Identification of Staphylococcus Aureus-Specific DNA Aptamers

    OpenAIRE

    Moon, Jihea; Kim, Giyoung; Park, Saet Byeol; Lim, Jongguk; Mo, Changyeun

    2015-01-01

    Whole-cell Systemic Evolution of Ligands by Exponential enrichment (SELEX) is the process by which aptamers specific to target cells are developed. Aptamers selected by whole-cell SELEX have high affinity and specificity for bacterial surface molecules and live bacterial targets. To identify DNA aptamers specific to Staphylococcus aureus, we applied our rapid whole-cell SELEX method to a single-stranded ssDNA library. To improve the specificity and selectivity of the aptamers, we designed, s...

  15. Screening and Identifying a Novel ssDNA Aptamer against Alpha-fetoprotein Using CE-SELEX

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    Dong, Lili; Tan, Qiwen; Ye, Wei; Liu, Dongli; Chen, Haifeng; Hu, Hongwei; Wen, Duo; Liu, Yang; Cao, Ya; Kang, Jingwu; Fan, Jia; Guo, Wei; Wu, Weizhong

    2015-01-01

    Alpha-fetoprotein (AFP) is a liver cancer associated protein and has long been utilized as a serum tumor biomarker of disease progression. AFP is usually detected in HCC patients by an antibody based system. Recently, however, aptamers generated from systematic evolution of ligands by exponential enrichment (SELEX) were reported to have an alternative potential in targeted imaging, diagnosis and therapy. In this study, AFP-bound ssDNA aptamers were screened and identified using capillary electrophoresis (CE) SELEX technology. After cloning, sequencing and motif analysis, we successfully confirmed an aptamer, named AP273, specifically targeting AFP. The aptamer could be used as a probe in AFP immunofluorescence imaging in HepG2, one AFP positive cancer cell line, but not in A549, an AFP negative cancer cell line. More interesting, the aptamer efficiently inhibited the migration and invasion of HCC cells after in vivo transfection. Motif analysis revealed that AP273 had several stable secondary motifs in its structure. Our results indicate that CE-SELEX technology is an efficient method to screen specific protein-bound ssDNA, and AP273 could be used as an agent in AFP-based staining, diagnosis and therapy, although more works are still needed. PMID:26497223

  16. Selection of aptamers for Candida albicans by cell-SELEX

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    Miranda, Alessandra Nunes Duarte

    2017-01-01

    The growing concern with invasive fungal infections, responsible for an alarming mortality rate of immunosuppressed patients and in Intensive Care Units, evidences the need for a fast and specific method for the Candida albicans detection, since this species is identified as one of the main causes of septicemia. Commonly, it is a challenge for clinicians to determine the primary infection foci, the dissemination degree, or whether the site of a particular surgery is involved. Although scintigraphic imaging represents a promising tool for infectious foci detection, it still lacks a methodology for C. albicans diagnosis due to the absence of specific radiotracers for this microorganism. Aptamers are molecules that have almost ideal properties for use as diagnostic radiopharmaceuticals, such as high specificity for their molecular targets, lack of immunogenicity and toxicity, high tissue penetration and rapid blood clearance. Aptamers can also be labeled with different radionuclides. This work aims to obtain aptamers for specific binding to C. albicans cells for future application as a radiopharmaceutical. It was used a variation of the SELEX (Systematic Evolution of Ligands by EXponential Enrichment) technique, termed cell-SELEX, in which cells are the targets for selection. A selection protocol was standardized using a random library of single-stranded oligonucleotides, each containing two fixed regions flanking a sequence of 40 random nucleotides. This library was incubated with C. albicans cells in the presence of competitors. Then, the binding sequences were separated by centrifugation, resuspended and amplified by PCR. The amplification was confirmed by agarose gel electrophoresis. After that, the ligands were purified to obtain a new pool of ssDNA, from which a new incubation was carried out. The selection parameters were gradually modified in order to increase stringency. This cycle was repeated 12 times to allow the selection of sequences with the maximum

  17. Selection of aptamers for Candida albicans by cell-SELEX; Selecao de aptameros para Candida albicans por cell-SELEX

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    Miranda, Alessandra Nunes Duarte

    2017-07-01

    The growing concern with invasive fungal infections, responsible for an alarming mortality rate of immunosuppressed patients and in Intensive Care Units, evidences the need for a fast and specific method for the Candida albicans detection, since this species is identified as one of the main causes of septicemia. Commonly, it is a challenge for clinicians to determine the primary infection foci, the dissemination degree, or whether the site of a particular surgery is involved. Although scintigraphic imaging represents a promising tool for infectious foci detection, it still lacks a methodology for C. albicans diagnosis due to the absence of specific radiotracers for this microorganism. Aptamers are molecules that have almost ideal properties for use as diagnostic radiopharmaceuticals, such as high specificity for their molecular targets, lack of immunogenicity and toxicity, high tissue penetration and rapid blood clearance. Aptamers can also be labeled with different radionuclides. This work aims to obtain aptamers for specific binding to C. albicans cells for future application as a radiopharmaceutical. It was used a variation of the SELEX (Systematic Evolution of Ligands by EXponential Enrichment) technique, termed cell-SELEX, in which cells are the targets for selection. A selection protocol was standardized using a random library of single-stranded oligonucleotides, each containing two fixed regions flanking a sequence of 40 random nucleotides. This library was incubated with C. albicans cells in the presence of competitors. Then, the binding sequences were separated by centrifugation, resuspended and amplified by PCR. The amplification was confirmed by agarose gel electrophoresis. After that, the ligands were purified to obtain a new pool of ssDNA, from which a new incubation was carried out. The selection parameters were gradually modified in order to increase stringency. This cycle was repeated 12 times to allow the selection of sequences with the maximum

  18. Comparison of whole-cell SELEX methods for the identification of Staphylococcus aureus-specific DNA aptamers.

    Science.gov (United States)

    Moon, Jihea; Kim, Giyoung; Park, Saet Byeol; Lim, Jongguk; Mo, Changyeun

    2015-04-15

    Whole-cell Systemic Evolution of Ligands by Exponential enrichment (SELEX) is the process by which aptamers specific to target cells are developed. Aptamers selected by whole-cell SELEX have high affinity and specificity for bacterial surface molecules and live bacterial targets. To identify DNA aptamers specific to Staphylococcus aureus, we applied our rapid whole-cell SELEX method to a single-stranded ssDNA library. To improve the specificity and selectivity of the aptamers, we designed, selected, and developed two categories of aptamers that were selected by two kinds of whole-cell SELEX, by mixing and combining FACS analysis and a counter-SELEX process. Using this approach, we have developed a biosensor system that employs a high affinity aptamer for detection of target bacteria. FAM-labeled aptamer sequences with high binding to S. aureus, as determined by fluorescence spectroscopic analysis, were identified, and aptamer A14, selected by the basic whole-cell SELEX using a once-off FACS analysis, and which had a high binding affinity and specificity, was chosen. The binding assay was evaluated using FACS analysis. Our study demonstrated the development of a set of whole-cell SELEX derived aptamers specific to S. aureus; this approach can be used in the identification of other bacteria.

  19. Comparison of Whole-Cell SELEX Methods for the Identification of Staphylococcus Aureus-Specific DNA Aptamers

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    Jihea Moon

    2015-04-01

    Full Text Available Whole-cell Systemic Evolution of Ligands by Exponential enrichment (SELEX is the process by which aptamers specific to target cells are developed. Aptamers selected by whole-cell SELEX have high affinity and specificity for bacterial surface molecules and live bacterial targets. To identify DNA aptamers specific to Staphylococcus aureus, we applied our rapid whole-cell SELEX method to a single-stranded ssDNA library. To improve the specificity and selectivity of the aptamers, we designed, selected, and developed two categories of aptamers that were selected by two kinds of whole-cell SELEX, by mixing and combining FACS analysis and a counter-SELEX process. Using this approach, we have developed a biosensor system that employs a high affinity aptamer for detection of target bacteria. FAM-labeled aptamer sequences with high binding to S. aureus, as determined by fluorescence spectroscopic analysis, were identified, and aptamer A14, selected by the basic whole-cell SELEX using a once-off FACS analysis, and which had a high binding affinity and specificity, was chosen. The binding assay was evaluated using FACS analysis. Our study demonstrated the development of a set of whole-cell SELEX derived aptamers specific to S. aureus; this approach can be used in the identification of other bacteria.

  20. Development of RNA aptamers as molecular probes for HER2+ breast cancer study using cell-SELEX

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    Seyedeh Alia Moosavian

    2015-06-01

    Full Text Available Objective(s: Development of molecules that specifically recognize cancer cells is one of the major areas in cancer research. Human epidermal growth factor receptor 2 (HER2 is specifically expressed on the surface of breast cancer cells. HER2 is associated with an aggressive phenotype and poor prognosis. In this study we aimed to isolate RNA aptamers that specifically bind to HER2 overexpressing TUBO cell line. Materials and Methods: Panel of aptamers was selected using cell-based systematic evolution of ligands by exponential enrichment (cell-SELEX. Results: Binding studies showed that selected aptamers can identify TUBO cell line with high affinity and selectivity. Our preliminary investigation of the target of aptamers suggested that aptamers bind with HER2 proteins on the surface of TUBO cells. Conclusion: We believe the selected aptamers could be useful ligands for targeted breast cancer therapy.

  1. Refining the Results of a Classical SELEX Experiment by Expanding the Sequence Data Set of an Aptamer Pool Selected for Protein A

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    Regina Stoltenburg

    2018-02-01

    Full Text Available New, as yet undiscovered aptamers for Protein A were identified by applying next generation sequencing (NGS to a previously selected aptamer pool. This pool was obtained in a classical SELEX (Systematic Evolution of Ligands by EXponential enrichment experiment using the FluMag-SELEX procedure followed by cloning and Sanger sequencing. PA#2/8 was identified as the only Protein A-binding aptamer from the Sanger sequence pool, and was shown to be able to bind intact cells of Staphylococcus aureus. In this study, we show the extension of the SELEX results by re-sequencing of the same aptamer pool using a medium throughput NGS approach and data analysis. Both data pools were compared. They confirm the selection of a highly complex and heterogeneous oligonucleotide pool and show consistently a high content of orphans as well as a similar relative frequency of certain sequence groups. But in contrast to the Sanger data pool, the NGS pool was clearly dominated by one sequence group containing the known Protein A-binding aptamer PA#2/8 as the most frequent sequence in this group. In addition, we found two new sequence groups in the NGS pool represented by PA-C10 and PA-C8, respectively, which also have high specificity for Protein A. Comparative affinity studies reveal differences between the aptamers and confirm that PA#2/8 remains the most potent sequence within the selected aptamer pool reaching affinities in the low nanomolar range of KD = 20 ± 1 nM.

  2. Refining the Results of a Classical SELEX Experiment by Expanding the Sequence Data Set of an Aptamer Pool Selected for Protein A.

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    Stoltenburg, Regina; Strehlitz, Beate

    2018-02-24

    New, as yet undiscovered aptamers for Protein A were identified by applying next generation sequencing (NGS) to a previously selected aptamer pool. This pool was obtained in a classical SELEX (Systematic Evolution of Ligands by EXponential enrichment) experiment using the FluMag-SELEX procedure followed by cloning and Sanger sequencing. PA#2/8 was identified as the only Protein A-binding aptamer from the Sanger sequence pool, and was shown to be able to bind intact cells of Staphylococcus aureus . In this study, we show the extension of the SELEX results by re-sequencing of the same aptamer pool using a medium throughput NGS approach and data analysis. Both data pools were compared. They confirm the selection of a highly complex and heterogeneous oligonucleotide pool and show consistently a high content of orphans as well as a similar relative frequency of certain sequence groups. But in contrast to the Sanger data pool, the NGS pool was clearly dominated by one sequence group containing the known Protein A-binding aptamer PA#2/8 as the most frequent sequence in this group. In addition, we found two new sequence groups in the NGS pool represented by PA-C10 and PA-C8, respectively, which also have high specificity for Protein A. Comparative affinity studies reveal differences between the aptamers and confirm that PA#2/8 remains the most potent sequence within the selected aptamer pool reaching affinities in the low nanomolar range of K D = 20 ± 1 nM.

  3. Fungal Systematics and Evolution: FUSE 1

    NARCIS (Netherlands)

    Crous, Pedro W; Schumacher, René K; Wingfield, Michael J; Lombard, Lorenzo; Giraldo, Alejandra; Christensen, Martha; Gardiennet, Alain; Nakashima, Chiharu; Pereira, Olinto L; Smith, Alexander J; Groenewald, Johannes Z

    2015-01-01

    Fungal Systematics and Evolution (FUSE) is introduced as a new series to expedite the publication of issues relating to the epitypification of formerly described species, report new sexual-asexual connections, the merging of sexual and asexual gen¬era following the end of dual nomenclature, and to

  4. Aptamer from whole-bacterium SELEX as new therapeutic reagent against virulent Mycobacterium tuberculosis

    International Nuclear Information System (INIS)

    Chen, Fan; Zhou, Jing; Luo, Fengling; Mohammed, Al-Bayati; Zhang, Xiao-Lian

    2007-01-01

    Worldwide, tuberculosis (TB) remains the most frequent and important infectious disease causing morbidity and death. One-third of the world's population is infected with Mycobacterium tuberculosis (MTB), the etiologic agent of TB. Because of the global health problems of TB, the development of potent new anti-TB drugs without cross-resistance with known antimycobacterial agents is urgently needed. In this study, we have applied a Systematic Evolution of Ligands by Exponential Enrichment (SELEX) process to identify a single aptamer (NK2) that binds to virulent strain M. tuberculosis (H37Rv) with high affinity and specificity. We have found that this aptamer improves CD4 + T cells to produce IFN-γ after binding to H37Rv. The different component between H37Rv and BCG was identified as some membrane protein. Moreover, the survival rates of mice challenged with i.v. H37Rv have been prolonged after treatment with single injection of aptamer NK2. The bacterial numbers were significantly lower in the spleen of mice treated with aptamer NK2. The histopathological examination of lung biopsy specimens showed lesser pulmonary alveolar fusion and swelling in the presence of the aptamer. These results suggest that aptamer NK2 has inhibitory effects on M. tuberculosis and can be used as antimycobacterial agent

  5. Whole-bacterium SELEX of DNA aptamers for rapid detection of E.coli O157:H7 using a QCM sensor.

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    Yu, Xiaofan; Chen, Fang; Wang, Ronghui; Li, Yanbin

    2018-01-20

    The rapid detection of foodborne pathogens is critical to ensure food safety. The objective of this study is to select aptamers specifically bound to Escherichia coli O157:H7 using the whole-bacterium SELEX (Systematic Evolution of Ligands by Exponential Enrichment) and apply the selected aptamer to a QCM (quartz crystal microbalance) sensor for rapid and sensitive detection of target bacteria. A total of 19 rounds of selection against live E. coli O157:H7 and 6 rounds of counter selection against a mixture of Staphylococcus aureus, Listeria monocytogenes, and Salmonella Typhimurium, were performed. The aptamer pool from the last round was cloned and sequenced. One sequence S1 that appeared 16 times was characterized and a dissociation constant (K d ) of 10.30nM was obtained. Subsequently, a QCM aptasensor was developed for the rapid detection of E. coli O157:H7. The limit of detection (LOD) and the detection time of the aptasensor was determined to be 1.46×10 3 CFU/ml and 50min, respectively. This study demonstrated that the ssDNA aptamer selected by the whole-bacterium SELEX possessed higher sensitivity than previous work and the potential use of the constructed QCM aptasensor in rapid screening of foodborne pathogens. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Fungal Systematics and Evolution: FUSE 1

    OpenAIRE

    Crous, Pedro W; Schumacher, René K; Wingfield, Michael J; Lombard, Lorenzo; Giraldo, Alejandra; Christensen, Martha; Gardiennet, Alain; Nakashima, Chiharu; Pereira, Olinto L; Smith, Alexander J; Groenewald, Johannes Z

    2015-01-01

    Fungal Systematics and Evolution (FUSE) is introduced as a new series to expedite the publication of issues relating to the epitypification of formerly described species, report new sexual-asexual connections, the merging of sexual and asexual gen¬era following the end of dual nomenclature, and to describe species or note interesting observations regarding fungi. This first paper includes 18 new combinations, 13 new species, three new genera and one new family. All taxa are ascomycetes, excep...

  7. Generation of Internal-Image Functional Aptamers of Okadaic Acid via Magnetic-Bead SELEX

    Directory of Open Access Journals (Sweden)

    Chao Lin

    2015-12-01

    Full Text Available Okadaic acid (OA is produced by Dinophysis and Prorocentrum dinoflagellates and primarily accumulates in bivalves, and this toxin has harmful effects on consumers and operators. In this work, we first report the use of aptamers as novel non-toxic probes capable of binding to a monoclonal antibody against OA (OA-mAb. Aptamers that mimic the OA toxin with high affinity and selectivity were generated by the magnetic bead-assisted systematic evolution of ligands by exponential enrichment (SELEX strategy. After 12 selection rounds, cloning, sequencing and enzyme-linked immunosorbent assay (ELISA analysis, four candidate aptamers (O24, O31, O39, O40 were selected that showed high affinity and specificity for OA-mAb. The affinity constants of O24, O31, O39 and O40 were 8.3 × 108 M−1, 1.47 × 109 M−1, 1.23 × 109 M−1 and 1.05 × 109 M−1, respectively. Indirect competitive ELISA was employed to determine the internal-image function of the aptamers. The results reveal that O31 has a similar competitive function as free OA toxin, whereas the other three aptamers did not bear the necessary internal-image function. Based on the derivation of the curvilinear equation for OA/O31, the equation that defined the relationship between the OA toxin content and O31 was Y = 2.185X − 1.78. The IC50 of O31 was 3.39 ng·mL−1, which was close to the value predicted by the OA ELISA (IC50 = 4.4 ng·mL−1; the IC10 was 0.33 ng·mL−1. The above data provides strong evidence that internal-image functional aptamers could be applicable as novel probes in a non-toxic assay.

  8. Capturing the target genes of BldD in Saccharopolyspora erythraea using improved genomic SELEX method.

    Science.gov (United States)

    Wu, Hang; Mao, Yongrong; Chen, Meng; Pan, Hui; Huang, Xunduan; Ren, Min; Wu, Hao; Li, Jiali; Xu, Zhongdong; Yuan, Hualing; Geng, Ming; Weaver, David T; Zhang, Lixin; Zhang, Buchang

    2015-03-01

    BldD (SACE_2077), a key developmental regulator in actinomycetes, is the first identified transcriptional factor in Saccharopolyspora erythraea positively regulating erythromycin production and morphological differentiation. Although the BldD of S. erythraea binds to the promoters of erythromycin biosynthetic genes, the interaction affinities are relatively low, implying the existence of its other target genes in S. erythraea. Through the genomic systematic evolution of ligands by exponential enrichment (SELEX) method that we herein improved, four DNA sequences of S. erythraea A226, corresponding to the promoter regions of SACE_0306 (beta-galactosidase), SACE_0811 (50S ribosomal protein L25), SACE_3410 (fumarylacetoacetate hydrolase), and SACE_6014 (aldehyde dehydrogenase), were captured with all three BldD concentrations of 0.5, 1, and 2 μM, while the previously identified intergenic regions of eryBIV-eryAI and ermE-eryCI plus the promoter region of SACE_7115, the amfC homolog for aerial mycelium formation, could be captured only when the BldD's concentration reached 2 μM. Electrophoretic mobility shift assay (EMSA) analysis indicated that BldD specifically bound to above seven DNA sequences, and quantitative real-time PCR (qRT-PCR) assay showed that the transcriptional levels of the abovementioned target genes decreased when bldD was disrupted in A226. Furthermore, SACE_7115 and SACE_0306 in A226 were individually inactivated, showing that SACE_7115 was predominantly involved in aerial mycelium formation, while SACE_0306 mainly controlled erythromycin production. This study provides valuable information for better understanding of the pleiotropic regulator BldD in S. erythraea, and the improved method may be useful for uncovering regulatory networks of other transcriptional factors.

  9. Identification of Salmonella Typhimurium-specific DNA aptamers developed using whole-cell SELEX and FACS analysis.

    Science.gov (United States)

    Moon, Jihea; Kim, Giyoung; Lee, Sangdae; Park, Saetbyeol

    2013-11-01

    Conventional methods for detection of infective organisms, such as Salmonella, are complicated and require multiple steps, and the need for rapid detection has increased. Biosensors show great potential for rapid detection of pathogens. In turn, aptamers have great potential for biosensor assay development, given their small size, ease of synthesis and labeling, lack of immunogenicity, a lower cost of production than antibodies, and high target specificity. In this study, ssDNA aptamers specific to Salmonella Typhimurium were obtained by a whole bacterium-based systematic evolution of ligands by exponential enrichment (SELEX) procedure and applied to probing S. Typhimurium. After 10 rounds of selection with S. Typhimurium as the target and Salmonella Enteritidis, Escherichia coli and Staphylococcus aureus as counter targets, the highly enriched oligonucleic acid pool was sorted using flow cytometry. In total, 12 aptamer candidates from different families were sequenced and grouped. Fluorescent analysis demonstrated that aptamer C4 had particularly high binding affinity and selectivity; this aptamer was then further characterized. © 2013 Elsevier B.V. All rights reserved.

  10. Fungal Systematics and Evolution: FUSE 3

    Czech Academy of Sciences Publication Activity Database

    Krisai-Greilhuber, I.; Chen, Y.; Jabeen, S.; Madrid, H.; Marincowitz, S.; Razaq, A.; Ševčíková, H.; Voglmayr, H.; Yazici, K.; Aptroot, A.; Aslan, A.; Boekhout, T.; Borovička, Jan; Crous, P.W.; Ilyas, S.; Jami, F.; Jiang, Y. L.; Khalid, A. N.; Kolecká, A.; Konvalinková, T.; Norphanphoun, C.; Shaheen, S.; Wang, Y.; Wingfield, M. J.; Wu, S. P.; Wu, Y. M.; Yu, J. Y.

    2017-01-01

    Roč. 36, 29 December 2017 (2017), s. 229-264 ISSN 0082-0598 Institutional support: RVO:67985831 Keywords : biodiversity * ITS varcodes * phylogeny * systematics Subject RIV: EF - Botanics OBOR OECD: Mycology Impact factor: 0.896, year: 2016

  11. Fungal Systematics and Evolution: FUSE 3

    Czech Academy of Sciences Publication Activity Database

    Krisai-Greilhuber, I.; Chen, Y.; Jabeen, S.; Madrid, H.; Marincowitz, S.; Razaq, A.; Ševčíková, H.; Voglmayr, H.; Yazici, K.; Aptroot, A.; Aslan, A.; Boekhout, T.; Borovička, Jan; Crous, P. W.; Ilyas, S.; Jami, F.; Jiang, Y. L.; Khalid, A. N.; Kolecká, A.; Konvalinková, Tereza; Norphanphoun, C.; Shaheen, S.; Wang, Y.; Wingfield, M. J.; Wu, S. P.; Wu, Y. M.; Yu, J. Y.

    2017-01-01

    Roč. 69, č. 12 (2017), s. 229-264 ISSN 0082-0598 Institutional support: RVO:61389005 ; RVO:61388971 Keywords : biodiversity * ITS varcodes * phylogeny * systematics Subject RIV: CB - Analytical Chemistry, Separation; EE - Microbiology, Virology (MBU-M) OBOR OECD: Analytical chemistry; Mycology (MBU-M) Impact factor: 0.896, year: 2016

  12. Evolution of the genus Aristolochia - Systematics, Molecular Evolution and Ecology

    OpenAIRE

    Wanke, Stefan

    2007-01-01

    Evolution of Piperales – matK gene and trnK intron sequence data reveal lineage specific resolution contrast. Piperales are one of the largest basal angiosperm orders with a nearly worldwide distribution. The order includes three species rich genera, Piper (ca. 1,000 species), Peperomia (ca. 1,500-1,700 species), and Aristolochia s. l. (ca. 500 species). Sequences of the matK gene and the non-coding trnK group II intron are analysed for a dense set of 105 taxa representing all families (excep...

  13. Evolution of PHP Applications: A Systematic Literature Review

    Directory of Open Access Journals (Sweden)

    Alinaswe Siame

    2017-03-01

    Full Text Available This paper reviews, some of the research work done in the evolution of PHP applications that have been around and are vastly used. PHP is currently one of the most popular programming languages, widely used in both the open source community and in industry to build large web-focused applications and application frameworks. This review looks at how PHP applications have evolved in terms of the use of libraries, the software maturity, adoption of object-orientation paradigm, the evolution of complexity and security. The results suggest that these systems undergo systematic maintenance and evolution is helping the underlying programming language to grow.

  14. Advances in SELEX ES infrared detectors for space and astronomy

    Science.gov (United States)

    Knowles, P.; Hipwood, L.; Baker, I.; Weller, H.

    2017-11-01

    Selex ES produces a wide range of infrared detectors from mercury cadmium telluride (MCT) and triglycine sulfate (TGS), and has supplied both materials into space programmes spanning a period of over 40 years. Current development activities that underpin potential future space missions include large format arrays for near- and short-wave infrared (NIR and SWIR) incorporating radiation-hard designs and suppression of glow. Improved heterostructures are aimed at the reduction of dark currents and avalanche photodiodes (APDs), and parallel studies have been undertaken for low-stress MCT array mounts. Much of this development work has been supported by ESA, UK Space, and ESO, and some has been performed in collaboration with the UK Astronomy Technology Centre and E2V. This paper focuses on MCT heterostructure developments and novel design elements in silicon read-out chips (ROICs). The 2048 x 2048 element, 17um pitch ROIC for ESA's SWIR array development forms the basis for the largest cooled infrared detector manufactured in Europe. Selex ES MCT is grown by metal organic vapour phase epitaxy (MOVPE), currently on 75mm diameter GaAs substrates. The MCT die size of the SWIR array is 35mm square and only a single array can be printed on the 75mm diameter wafer, utilising only 28% of the wafer area. The situation for 100mm substrates is little better, allowing only 2 arrays and 31% utilisation. However, low cost GaAs substrates are readily available in 150mm diameter and the MCT growth is scalable to this size, offering the real possibility of 6 arrays per wafer with 42% utilisation. A similar 2k x 2k ROIC is the goal of ESA's NIR programme, which is currently in phase 2 with a 1k x 1k demonstrator, and a smaller 320 x 256 ROIC (SAPHIRA) has been designed for ESO for the adaptive optics application in the VLT Gravity instrument. All 3 chips have low noise source-follower architecture and are enabled for MCT APD arrays, which have been demonstrated by ESO to be capable of

  15. The Evolution of American Hospital Ethics Committees: A Systematic Review.

    Science.gov (United States)

    Courtwright, Andrew; Jurchak, Martha

    2016-01-01

    During the 1970s and 1980s, legal precedent, governmental recommendations, and professional society guidelines drove the formation of hospital ethics committees (HECs). The Joint Commission on Accreditation of Health Care Organization's requirements in the early 1990s solidified the role of HECs as the primary mechanism to address ethical issues in patient care. Because external factors drove the rapid growth of HECs on an institution-by-institution basis, however, no initial consensus formed around the structure and function of these committees. There are now almost 40 years of empirical studies on the composition, administration, and activities of HECs in the United States. We conducted a systematic review of the available empirical literature on HECs to describe their evolution. As HECs changed over time, they increased their total number of members and percentage of members from nursing and the community. Although physicians increasingly chaired these committees, their presence as a percentage of overall members declined. The percentage of administrative members remained steady, although committees became increasingly likely to have at least one administrative member. HECs were also increasingly likely to report to an administrative body or to the board of trustees or directors rather than to the medical staff. Finally, consultation volume increased steadily over time. There has not, however, been a national survey of the composition of ethics committees, their administration, or volume of consultation in more than 10 years, despite increasing calls for professional standards and quality improvement assessments among HECs. Copyright 2016 The Journal of Clinical Ethics. All rights reserved.

  16. Monogenean anchor morphometry: systematic value, phylogenetic signal, and evolution

    Science.gov (United States)

    Soo, Oi Yoon Michelle; Tan, Wooi Boon; Lim, Lee Hong Susan

    2016-01-01

    point, and the length between the inner root point and the dent point. The species on M. buchanani evolved larger, more robust anchors; those on L. subviridis evolved smaller, more delicate anchors. Anchor shape and size were significantly correlated, suggesting constraints in anchor evolution. Tight integration between the root and the point compartments within anchors confirms the anchor as a single, fully integrated module. The correlation between male copulatory organ morphology and size with anchor shape was consistent with predictions from the Rohde-Hobbs hypothesis. Conclusions. Monogenean anchors are tightly integrated structures, and their shape variation correlates strongly with phylogeny, thus underscoring their value for systematic and evolutionary biology studies. Our MonogeneaGM R package provides tools for researchers to mine biological insights from geometric morphometric data of speciose monogenean genera. PMID:26966649

  17. A Capture-SELEX Strategy for Multiplexed Selection of RNA Aptamers Against Small Molecules

    DEFF Research Database (Denmark)

    Lauridsen, Lasse Holm; Doessing, Holger B.; Long, Katherine S.

    2018-01-01

    -SELEX, a selection strategy that uses an RNA library to yield ligand-responsive RNA aptamers targeting small organic molecules in solution. To demonstrate the power of this method we selected several aptamers with specificity towards either the natural sweetener rebaudioside A or the food-coloring agent carminic...

  18. SELEX: Recent Progress in the Analysis of Charm-Strange and Double-Charm Baryons

    International Nuclear Information System (INIS)

    Engelfried, Jurgen

    2007-01-01

    SELEX (Fermilab Experiment 781) [1] employs beams of Σ - , π - , and protons at around 600 GeV/c to study production and decay properties of charmed baryons. It took data in the 1996/7 fixed target run and is currently analyzing those data. Here they focus on recently obtained results concerning the (Omega) c 0 lifetime and the doubly-charmed baryons Ξ cc + and Ξ cc ++

  19. Transcription profile of Escherichia coli: genomic SELEX search for regulatory targets of transcription factors.

    Science.gov (United States)

    Ishihama, Akira; Shimada, Tomohiro; Yamazaki, Yukiko

    2016-03-18

    Bacterial genomes are transcribed by DNA-dependent RNA polymerase (RNAP), which achieves gene selectivity through interaction with sigma factors that recognize promoters, and transcription factors (TFs) that control the activity and specificity of RNAP holoenzyme. To understand the molecular mechanisms of transcriptional regulation, the identification of regulatory targets is needed for all these factors. We then performed genomic SELEX screenings of targets under the control of each sigma factor and each TF. Here we describe the assembly of 156 SELEX patterns of a total of 116 TFs performed in the presence and absence of effector ligands. The results reveal several novel concepts: (i) each TF regulates more targets than hitherto recognized; (ii) each promoter is regulated by more TFs than hitherto recognized; and (iii) the binding sites of some TFs are located within operons and even inside open reading frames. The binding sites of a set of global regulators, including cAMP receptor protein, LeuO and Lrp, overlap with those of the silencer H-NS, suggesting that certain global regulators play an anti-silencing role. To facilitate sharing of these accumulated SELEX datasets with the research community, we compiled a database, 'Transcription Profile of Escherichia coli' (www.shigen.nig.ac.jp/ecoli/tec/). © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

  20. In vivo SELEX for Identification of Brain-penetrating Aptamers

    Directory of Open Access Journals (Sweden)

    Congsheng Cheng

    2013-01-01

    Full Text Available The physiological barriers of the brain impair drug delivery for treatment of many neurological disorders. One delivery approach that has not been investigated for their ability to penetrate the brain is RNA-based aptamers. These molecules can impart delivery to peripheral tissues and circulating immune cells, where they act as ligand mimics or can be modified to carry payloads. We developed a library of aptamers and an in vivo evolution protocol to determine whether specific aptamers could be identified that would home to the brain after injection into the peripheral vasculature. Unlike biopanning with recombinant bacteriophage libraries, we found that the aptamer library employed here required more than 15 rounds of in vivo selection for convergence to specific sequences. The aptamer species identified through this approach bound to brain capillary endothelia and penetrated into the parenchyma. The methods described may find general utility for targeting various payloads to the brain.

  1. Photon detector for high energy measurements in the SELEX spectrometer (Fermilab experiment E781)

    International Nuclear Information System (INIS)

    Goncharenko, Yu.M.; Grachov, O.A.; Kurshetsov, V.F.; Landsberg, L.G.; Nurushev, S.B.; Vasil'ev, A.N.

    1995-01-01

    A possibility to use one- or two-photon lead glass detectors for high energy measurements in the SELEX spectrometer with E γ up to 500 GeV is studied. It is shown that a single photon detector equipped with radiation-resistant lead glass counters is applicable for the experiment discussed. It is concluded that for the best energy resolution in the case of Primakoff effect like π - = γ * → π - + γ the combined method would be used with weighted combination of direct E γ measurement in the Photon-3 detector and the π - beam energy precise measurement. 11 refs., 4 tabs., 17 figs

  2. eCodonOpt: a systematic computational framework for optimizing codon usage in directed evolution experiments

    OpenAIRE

    Moore, Gregory L.; Maranas, Costas D.

    2002-01-01

    We present a systematic computational framework, eCodonOpt, for designing parental DNA sequences for directed evolution experiments through codon usage optimization. Given a set of homologous parental proteins to be recombined at the DNA level, the optimal DNA sequences encoding these proteins are sought for a given diversity objective. We find that the free energy of annealing between the recombining DNA sequences is a much better descriptor of the extent of crossover formation than sequence...

  3. A SELEX-screened aptamer of human hepatitis B virus RNA encapsidation signal suppresses viral replication.

    Directory of Open Access Journals (Sweden)

    Hui Feng

    Full Text Available BACKGROUND: The specific interaction between hepatitis B virus (HBV polymerase (P protein and the ε RNA stem-loop on pregenomic (pg RNA is crucial for viral replication. It triggers both pgRNA packaging and reverse transcription and thus represents an attractive antiviral target. RNA decoys mimicking ε in P protein binding but not supporting replication might represent novel HBV inhibitors. However, because generation of recombinant enzymatically active HBV polymerase is notoriously difficult, such decoys have as yet not been identified. METHODOLOGY/PRINCIPAL FINDINGS: Here we used a SELEX approach, based on a new in vitro reconstitution system exploiting a recombinant truncated HBV P protein (miniP, to identify potential ε decoys in two large ε RNA pools with randomized upper stem. Selection of strongly P protein binding RNAs correlated with an unexpected strong enrichment of A residues. Two aptamers, S6 and S9, displayed particularly high affinity and specificity for miniP in vitro, yet did not support viral replication when part of a complete HBV genome. Introducing S9 RNA into transiently HBV producing HepG2 cells strongly suppressed pgRNA packaging and DNA synthesis, indicating the S9 RNA can indeed act as an ε decoy that competitively inhibits P protein binding to the authentic ε signal on pgRNA. CONCLUSIONS/SIGNIFICANCE: This study demonstrates the first successful identification of human HBV ε aptamers by an in vitro SELEX approach. Effective suppression of HBV replication by the S9 aptamer provides proof-of-principle for the ability of ε decoy RNAs to interfere with viral P-ε complex formation and suggests that S9-like RNAs may further be developed into useful therapeutics against chronic hepatitis B.

  4. An integrative systematic framework helps to reconstruct skeletal evolution of glass sponges (Porifera, Hexactinellida).

    Science.gov (United States)

    Dohrmann, Martin; Kelley, Christopher; Kelly, Michelle; Pisera, Andrzej; Hooper, John N A; Reiswig, Henry M

    2017-01-01

    Glass sponges (Class Hexactinellida) are important components of deep-sea ecosystems and are of interest from geological and materials science perspectives. The reconstruction of their phylogeny with molecular data has only recently begun and shows a better agreement with morphology-based systematics than is typical for other sponge groups, likely because of a greater number of informative morphological characters. However, inconsistencies remain that have far-reaching implications for hypotheses about the evolution of their major skeletal construction types (body plans). Furthermore, less than half of all described extant genera have been sampled for molecular systematics, and several taxa important for understanding skeletal evolution are still missing. Increased taxon sampling for molecular phylogenetics of this group is therefore urgently needed. However, due to their remote habitat and often poorly preserved museum material, sequencing all 126 currently recognized extant genera will be difficult to achieve. Utilizing morphological data to incorporate unsequenced taxa into an integrative systematics framework therefore holds great promise, but it is unclear which methodological approach best suits this task. Here, we increase the taxon sampling of four previously established molecular markers (18S, 28S, and 16S ribosomal DNA, as well as cytochrome oxidase subunit I) by 12 genera, for the first time including representatives of the order Aulocalycoida and the type genus of Dactylocalycidae, taxa that are key to understanding hexactinellid body plan evolution. Phylogenetic analyses suggest that Aulocalycoida is diphyletic and provide further support for the paraphyly of order Hexactinosida; hence these orders are abolished from the Linnean classification. We further assembled morphological character matrices to integrate so far unsequenced genera into phylogenetic analyses in maximum parsimony (MP), maximum likelihood (ML), Bayesian, and morphology-based binning

  5. DNA aptamer evolved by cell-SELEX for recognition of prostate cancer.

    Directory of Open Access Journals (Sweden)

    Yuanyuan Wang

    Full Text Available Morbidity and mortality of prostate cancer (PCa have increased in recent years worldwide. Currently existing methods for diagnosis and treatment do not make the situation improve, especially for hormone refractory prostate cancer (HRPC. The lack of molecular probes for PCa hindered the early diagnosis of metastasis and accurate staging for PCa. In this work, we have developed a new aptamer probe Wy-5a against PCa cell line PC-3 by cell-SELEX technique. Wy-5a shows high specificity to the target cells with dissociation constants in the nanomolar range, and does not recognize other tested PCa cell lines and other tested tumor cell lines. The staining of clinical tissue sections with fluorescent dye labeled Wy-5a shows that sections from high risk group with metastasis exhibited stronger fluorescence and sections from Benign Prostatic Hyperplasia (BPH did not exhibit notable fluorescence, which suggests that aptamer Wy-5a may bind to protein related to the progression of PCa. The high affinity and specificity of Wy-5a makes this aptamer hold potential for application in diagnosis and target therapy of PCa.

  6. Revealing the secrets of African annonaceae : systematics, evolution and biogeography of the syncarpous genera Isolona and Monodora

    NARCIS (Netherlands)

    Couvreur, T.L.P.

    2008-01-01

    The goal of this PhD project was to study the evolution, systematics and biogeography of two African genera from the pan-tropical Annonaceae family: Isolona and Monodora. Both genera are unique within the family in that the female reproductive parts (or carpels) are fused into a single unit. All

  7. Systematic analysis and evolution of 5S ribosomal DNA in metazoans.

    Science.gov (United States)

    Vierna, J; Wehner, S; Höner zu Siederdissen, C; Martínez-Lage, A; Marz, M

    2013-11-01

    Several studies on 5S ribosomal DNA (5S rDNA) have been focused on a subset of the following features in mostly one organism: number of copies, pseudogenes, secondary structure, promoter and terminator characteristics, genomic arrangements, types of non-transcribed spacers and evolution. In this work, we systematically analyzed 5S rDNA sequence diversity in available metazoan genomes, and showed organism-specific and evolutionary-conserved features. Putatively functional sequences (12,766) from 97 organisms allowed us to identify general features of this multigene family in animals. Interestingly, we show that each mammal species has a highly conserved (housekeeping) 5S rRNA type and many variable ones. The genomic organization of 5S rDNA is still under debate. Here, we report the occurrence of several paralog 5S rRNA sequences in 58 of the examined species, and a flexible genome organization of 5S rDNA in animals. We found heterogeneous 5S rDNA clusters in several species, supporting the hypothesis of an exchange of 5S rDNA from one locus to another. A rather high degree of variation of upstream, internal and downstream putative regulatory regions appears to characterize metazoan 5S rDNA. We systematically studied the internal promoters and described three different types of termination signals, as well as variable distances between the coding region and the typical termination signal. Finally, we present a statistical method for detection of linkage among noncoding RNA (ncRNA) gene families. This method showed no evolutionary-conserved linkage among 5S rDNAs and any other ncRNA genes within Metazoa, even though we found 5S rDNA to be linked to various ncRNAs in several clades.

  8. Magnetic microparticle-based SELEX process for the identification of highly specific aptamers of heart marker--brain natriuretic peptide

    International Nuclear Information System (INIS)

    Wang, Ying; Cao, Jinxuan; Wu, Jingjing; Xue, Feng; Teng, Jun; Chen, Wei; Chen, Yinji; Lu, Chunxia

    2015-01-01

    The brain natriuretic peptide (BNP) is known to be an effective indicator of heart failure. It has been widely adopted as a parameter for the evaluation of heart function of cardiovascular and cerebrovascular diseases (CVDs). Current immune-recognition based methods for the detection of BNP are limited, to a certain extent, by the poor stability of the antibody and by high costs. The availability of an aptamer specific for BNP would greatly assist in the rapid and early diagnosis of CVDs. In order to screen for such an aptamer by the SELEX method, we have used magnetic microparticles (m-MPs) as the separation substrate for immobilization of target BNP. The use of m-MPs for rapid separation of combined aptamers enables bound oligonucleotides to be separated directly, quickly, and with high efficiency. After 14 rounds of selection, a panel of six aptamers against BNP was identified. Their dissociation constants range from 12.5 to 139 nM. The classical technique for conjugation of a target to m-MPs is known to be applicable to various fields, and we conclude that this m-MP-based SELEX process provides a general strategy for screening of specific aptamers against various analytes. (author)

  9. The evolution of mobile apps for asthma: an updated systematic assessment of content and tools.

    Science.gov (United States)

    Huckvale, Kit; Morrison, Cecily; Ouyang, Jing; Ghaghda, Aseem; Car, Josip

    2015-03-23

    Interest in mobile apps that support long-term conditions such as asthma is matched by recognition of the importance of the quality and safety of apps intended for patient use. We assessed how changes over a 2-year period affected the clinical suitability of apps providing self-management information and tools for people with asthma by updating a review first performed in 2011. Systematic content assessment of all apps for iOS and Android examining the comprehensiveness of asthma information, consistency with the evidence base for asthma self-management and adherence to best practice principles for trustworthy content, comparing the quality of apps available in 2011 to those released since. Between 2011 and 2013, numbers of asthma apps more than doubled from 93 to 191, despite withdrawal of 25% (n = 23/93) of existing apps. Newer apps were no more likely than those available in 2011 to include comprehensive information, such as the use of action plans, or offer guidance consistent with evidence; 13% (n = 19/147) of all apps, and 39% (n = 9/23) of those intended to manage acute asthma, recommended self-care procedures unsupported by evidence. Despite increases in the numbers of apps targeting specific skills, such as acute asthma management (n = 12 to 23) and inhaler technique (from n = 2 to 12), the proportion consistent with guidelines (17%, n = 4/23) and inhaler instructions (25%, n = 3/12), respectively, was low, and most apps provided only either basic information about asthma (50%, n = 75/147) or simple diary functions (24%, n = 36/147). In addition to persisting questions about clinical quality and safety, dynamic aspects of app turnover and feature evolution affect the suitability of asthma apps for use in routine care. The findings underline the need for coordinated quality assurance processes that can adapt to changing clinical and information governance-related risks, ensure compliance with the evidence base and reflect

  10. Classification and Comparison of Architecture Evolution Reuse Knowledge - A Systematic Review

    DEFF Research Database (Denmark)

    Ahmad, Aakash; Jamshidi, Pooyan; Pahl, Claus

    2014-01-01

    patterns (34% of selected studies) represent a predominant solution, followed by evolution styles (25%) and adaptation strategies and policies (22%) to enable application of reuse knowledge. Empirical methods for acquisition of reuse knowledge represent 19% including pattern discovery, configuration...

  11. Molecular and morphological systematics of the Ellisellidae (Coelenterata: Octocorallia): Parallel evolution in a globally distributed family of octocorals

    KAUST Repository

    Bilewitch, Jaret P.

    2014-04-01

    The octocorals of the Ellisellidae constitute a diverse and widely distributed family with subdivisions into genera based on colonial growth forms. Branching patterns are repeated in several genera and congeners often display region-specific variations in a given growth form. We examined the systematic patterns of ellisellid genera and the evolution of branching form diversity using molecular phylogenetic and ancestral morphological reconstructions. Six of eight included genera were found to be polyphyletic due to biogeographical incompatibility with current taxonomic assignments and the creation of at least six new genera plus several reassignments among existing genera is necessary. Phylogenetic patterns of diversification of colony branching morphology displayed a similar transformation order in each of the two primary ellisellid clades, with a sea fan form estimated as the most-probable common ancestor with likely origins in the Indo-Pacific region. The observed parallelism in evolution indicates the existence of a constraint on the genetic elements determining ellisellid colonial morphology. However, the lack of correspondence between levels of genetic divergence and morphological diversity among genera suggests that future octocoral studies should focus on the role of changes in gene regulation in the evolution of branching patterns. © 2014 Elsevier Inc.

  12. Molecular and morphological systematics of the Ellisellidae (Coelenterata: Octocorallia): Parallel evolution in a globally distributed family of octocorals

    KAUST Repository

    Bilewitch, Jaret P.; Ekins, Merrick; Hooper, John; Degnan, Sandie M.

    2014-01-01

    The octocorals of the Ellisellidae constitute a diverse and widely distributed family with subdivisions into genera based on colonial growth forms. Branching patterns are repeated in several genera and congeners often display region-specific variations in a given growth form. We examined the systematic patterns of ellisellid genera and the evolution of branching form diversity using molecular phylogenetic and ancestral morphological reconstructions. Six of eight included genera were found to be polyphyletic due to biogeographical incompatibility with current taxonomic assignments and the creation of at least six new genera plus several reassignments among existing genera is necessary. Phylogenetic patterns of diversification of colony branching morphology displayed a similar transformation order in each of the two primary ellisellid clades, with a sea fan form estimated as the most-probable common ancestor with likely origins in the Indo-Pacific region. The observed parallelism in evolution indicates the existence of a constraint on the genetic elements determining ellisellid colonial morphology. However, the lack of correspondence between levels of genetic divergence and morphological diversity among genera suggests that future octocoral studies should focus on the role of changes in gene regulation in the evolution of branching patterns. © 2014 Elsevier Inc.

  13. In vitro Selection and Interaction Studies of a DNA Aptamer Targeting Protein A

    OpenAIRE

    Stoltenburg, Regina; Schubert, Thomas; Strehlitz, Beate

    2015-01-01

    A new DNA aptamer targeting Protein A is presented. The aptamer was selected by use of the FluMag-SELEX procedure. The SELEX technology (Systematic Evolution of Ligands by EXponential enrichment) is widely applied as an in vitro selection and amplification method to generate target-specific aptamers and exists in various modified variants. FluMag-SELEX is one of them and is characterized by the use of magnetic beads for target immobilization and fluorescently labeled oligonucleotides for moni...

  14. A Systematic Procedure to Describe Shale Gas Permeability Evolution during the Production Process

    Science.gov (United States)

    Jia, B.; Tsau, J. S.; Barati, R.

    2017-12-01

    Gas flow behavior in shales is complex due to the multi-physics nature of the process. Pore size reduces as the in-situ stress increases during the production process, which will reduce intrinsic permeability of the porous media. Slip flow/pore diffusion enhances gas apparent permeability, especially under low reservoir pressures. Adsorption not only increases original gas in place but also influences gas flow behavior because of the adsorption layer. Surface diffusion between free gas and adsorption phase enhances gas permeability. Pore size reduction and the adsorption layer both have complex impacts on gas apparent permeability and non-Darcy flow might be a major component in nanopores. Previously published literature is generally incomplete in terms of coupling of all these four physics with fluid flow during gas production. This work proposes a methodology to simultaneously take them into account to describe a permeability evolution process. Our results show that to fully describe shale gas permeability evolution during gas production, three sets of experimental data are needed initially: 1) intrinsic permeability under different in-situ stress, 2) adsorption isotherm under reservoir conditions and 3) surface diffusivity measurement by the pulse-decay method. Geomechanical effects, slip flow/pore diffusion, adsorption layer and surface diffusion all play roles affecting gas permeability. Neglecting any of them might lead to misleading results. The increasing in-situ stress during shale gas production is unfavorable to shale gas flow process. Slip flow/pore diffusion is important for gas permeability under low pressures in the tight porous media. They might overwhelm the geomechanical effect and enhance gas permeability at low pressures. Adsorption layer reduces the gas permeability by reducing the effective pore size, but the effect is limited. Surface diffusion increases gas permeability more under lower pressures. The total gas apparent permeability might

  15. SEMI-EMPIRICAL WHITE DWARF INITIAL-FINAL MASS RELATIONSHIPS: A THOROUGH ANALYSIS OF SYSTEMATIC UNCERTAINTIES DUE TO STELLAR EVOLUTION MODELS

    International Nuclear Information System (INIS)

    Salaris, Maurizio; Serenelli, Aldo; Weiss, Achim; Miller Bertolami, Marcelo

    2009-01-01

    Using the most recent results about white dwarfs (WDs) in ten open clusters, we revisit semiempirical estimates of the initial-final mass relation (IFMR) in star clusters, with emphasis on the use of stellar evolution models. We discuss the influence of these models on each step of the derivation. One intention of our work is to use consistent sets of calculations both for the isochrones and the WD cooling tracks. The second one is to derive the range of systematic errors arising from stellar evolution theory. This is achieved by using different sources for the stellar models and by varying physical assumptions and input data. We find that systematic errors, including the determination of the cluster age, are dominating the initial mass values, while observational uncertainties influence the final mass primarily. After having determined the systematic errors, the initial-final mass relation allows us finally to draw conclusions about the physics of the stellar models, in particular about convective overshooting.

  16. Evolution of the protists and protistan parasites from the perspective of molecular systematics.

    Science.gov (United States)

    Sogin, M L; Silberman, J D

    1998-01-01

    Unlike prokaryotes, the Protista are rich in morphological and ultrastructure information. Their amazing phenotypic diversity permits assignment of many protists to cohesive phyletic assemblages but sometimes blurs relationships between major lineages. With the advent of molecular techniques, it became possible to test evolutionary hypotheses that were originally formulated according to shared phenotypic traits. More than any other gene family, studies of rRNAs changed our understanding of protist evolution. Stramenopiles (oomycetes, chrysophytes, phaeophytes, synurophytes, diatoms, xanthophytes, bicosoecids, slime nets) and alveolates (dinoflagellates, apicomplexans, ciliates) are two novel, complex evolutionary assemblages which diverged nearly simultaneously with animals, fungi, plants, rhodophytes, haptophytes and a myriad of independent amoeboid lineages. Their separation may have occurred one billion years ago and collectively these lineages make up the "crown" of the eukaryotic tree. Deeper branches in the eukaryotic tree show 16S-like rRNA sequence variation that is much greater than that observed within the Archaea and the Bacteria. A progression of independent protist branches, some as ancient as the divergence between the two prokaryotic domains, preceded the sudden radiation of "crown" groups. Trichomonads, diplomonads and Microsporidia are basal to all other eukaryotes included in rRNA studies. Together with pelobionts, oxymonads, retortamonads and hypermastigids, these amitochondriate taxa comprise the Archaezoa. This skeletal phylogeny suggested that early branching eukaryotes lacked mitochondria, peroxisomes and typical stacked Golgi dictyosomes. However, recent studies of heat shock proteins indicate that the first eukaryotes may have had mitochondria. When evaluated in terms of evolution of ultrastructure, lifestyles and other phenotypic traits, the rRNA phylogenies provide the most consistent of molecular trees. They permit identification of the

  17. Systematics and plastid genome evolution of the cryptically photosynthetic parasitic plant genus Cuscuta (Convolvulaceae

    Directory of Open Access Journals (Sweden)

    Kuehl Jennifer V

    2007-12-01

    Full Text Available Abstract Background The genus Cuscuta L. (Convolvulaceae, commonly known as dodders, are epiphytic vines that invade the stems of their host with haustorial feeding structures at the points of contact. Although they lack expanded leaves, some species are noticeably chlorophyllous, especially as seedlings and in maturing fruits. Some species are reported as crop pests of worldwide distribution, whereas others are extremely rare and have local distributions and apparent niche specificity. A strong phylogenetic framework for this large genus is essential to understand the interesting ecological, morphological and molecular phenomena that occur within these parasites in an evolutionary context. Results Here we present a well-supported phylogeny of Cuscuta using sequences of the nuclear ribosomal internal transcribed spacer and plastid rps2, rbcL and matK from representatives across most of the taxonomic diversity of the genus. We use the phylogeny to interpret morphological and plastid genome evolution within the genus. At least three currently recognized taxonomic sections are not monophyletic and subgenus Cuscuta is unequivocally paraphyletic. Plastid genes are extremely variable with regards to evolutionary constraint, with rbcL exhibiting even higher levels of purifying selection in Cuscuta than photosynthetic relatives. Nuclear genome size is highly variable within Cuscuta, particularly within subgenus Grammica, and in some cases may indicate the existence of cryptic species in this large clade of morphologically similar species. Conclusion Some morphological characters traditionally used to define major taxonomic splits within Cuscuta are homoplastic and are of limited use in defining true evolutionary groups. Chloroplast genome evolution seems to have evolved in a punctuated fashion, with episodes of loss involving suites of genes or tRNAs followed by stabilization of gene content in major clades. Nearly all species of Cuscuta retain some

  18. Systematics and plastid genome evolution of the cryptically photosynthetic parasitic plant genus Cuscuta (Convolvulaceae).

    Science.gov (United States)

    McNeal, Joel R; Arumugunathan, Kathiravetpilla; Kuehl, Jennifer V; Boore, Jeffrey L; Depamphilis, Claude W

    2007-12-13

    The genus Cuscuta L. (Convolvulaceae), commonly known as dodders, are epiphytic vines that invade the stems of their host with haustorial feeding structures at the points of contact. Although they lack expanded leaves, some species are noticeably chlorophyllous, especially as seedlings and in maturing fruits. Some species are reported as crop pests of worldwide distribution, whereas others are extremely rare and have local distributions and apparent niche specificity. A strong phylogenetic framework for this large genus is essential to understand the interesting ecological, morphological and molecular phenomena that occur within these parasites in an evolutionary context. Here we present a well-supported phylogeny of Cuscuta using sequences of the nuclear ribosomal internal transcribed spacer and plastid rps2, rbcL and matK from representatives across most of the taxonomic diversity of the genus. We use the phylogeny to interpret morphological and plastid genome evolution within the genus. At least three currently recognized taxonomic sections are not monophyletic and subgenus Cuscuta is unequivocally paraphyletic. Plastid genes are extremely variable with regards to evolutionary constraint, with rbcL exhibiting even higher levels of purifying selection in Cuscuta than photosynthetic relatives. Nuclear genome size is highly variable within Cuscuta, particularly within subgenus Grammica, and in some cases may indicate the existence of cryptic species in this large clade of morphologically similar species. Some morphological characters traditionally used to define major taxonomic splits within Cuscuta are homoplastic and are of limited use in defining true evolutionary groups. Chloroplast genome evolution seems to have evolved in a punctuated fashion, with episodes of loss involving suites of genes or tRNAs followed by stabilization of gene content in major clades. Nearly all species of Cuscuta retain some photosynthetic ability, most likely for nutrient

  19. From Ugly Duckling to Swan: Unexpected Identification from Cell-SELEX of an Anti-Annexin A2 Aptamer Targeting Tumors

    Science.gov (United States)

    Cibiel, Agnes; Nguyen Quang, Nam; Gombert, Karine; Thézé, Benoit; Garofalakis, Anikitos; Ducongé, Frédéric

    2014-01-01

    Background Cell-SELEX is now widely used for the selection of aptamers against cell surface biomarkers. However, despite negative selection steps using mock cells, this method sometimes results in aptamers against undesirable targets that are expressed both on mock and targeted cells. Studying these junk aptamers might be useful for further applications than those originally envisaged. Methodology/Principal Findings Cell-SELEX was performed to identify aptamers against CHO-K1 cells expressing human Endothelin type B receptor (ETBR). CHO-K1 cells were used for negative selection of aptamers. Several aptamers were identified but no one could discriminate between both cell lines. We decided to study one of these aptamers, named ACE4, and we identified that it binds to the Annexin A2, a protein overexpressed in many cancers. Radioactive binding assays and flow cytometry demonstrated that the aptamer was able to bind several cancer cell lines from different origins, particularly the MCF-7 cells. Fluorescence microscopy revealed it could be completely internalized in cells in 2 hours. Finally, the tumor targeting of the aptamer was evaluated in vivo in nude mice xenograft with MCF-7 cells using fluorescence diffuse optical tomography (fDOT) imaging. Three hours after intravenous injection, the aptamer demonstrated a significantly higher uptake in the tumor compared to a scramble sequence. Conclusions/Significance Although aptamers could be selected during cell-SELEX against other targets than those initially intended, they represent a potential source of ligands for basic research, diagnoses and therapy. Here, studying such aptamers, we identify one with high affinity for Annexin A2 that could be a promising tool for biomedical application. PMID:24489826

  20. Resolving the SELEX--LHCb Double-Charm Baryon Conflict: The Impact of Intrinsic Heavy-Quark Hadroproduction and Supersymmetric Light-Front Holographic QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2017-01-01

    In this paper we show that the intrinsic heavy-quark QCD mechanism for the hadroproduction of heavy hadrons at large $x_F$ can resolve the apparent conflict between measurements of double-charm baryons by the SELEX fixed-target experiment and the LHCb experiment at the LHC collider. We show that both experiments are compatible, and that both results can be correct. The observed spectroscopy of double-charm hadrons is in agreement with the predictions of supersymmetric light front holographic QCD.

  1. [Evolution of the concept of positive mental health: a systematic review].

    Science.gov (United States)

    Muñoz, Cristóbal Ovidio; Restrepo, Diego; Cardona, Doris

    2016-03-01

    Objective Characterize the theoretical models that have underpinned empirical research on the concept of positive mental health from the time it first emerged in the field of health up to the present. Methods A systematic search of the literature was conducted in PubMed, EBSCO (including Academic Search Complete, ERIC, Academic Source, MasterFILE Premier, MedicLatina, MEDLINE, and the Psychology and Behavioral Sciences Collection), Science Direct, Psicodoc, Springer Link, Taylor & Francis, Wiley Online Library, Directory of Open Access Journals (DOAJ), Redalyc, SciELO, Ovid, Embase, and ProQuest (including Health and Medical Complete, the Nursing and Allied Health Source, Psychology Journals, and Social Science Journals). The search criterion was the descriptor "positive mental health." Results Of 51 studies consulted, 84% used a quantitative approach; 84% were published in English; and the same percentage were conducted between 2000 and 2014. The concept of positive mental health has been applied in essentially five different ways: as the absence of disease; as the subject of the Jahoda model; as a combination of factors on the Lluch scale; as a synonym of well-being; and as part of more complex scales of measurement. Conclusions Positive mental health should not be viewed as the opposite of a mental disorder, the absence of disease, or the sum of a given set of personal conditions. It is important to move forward in the development of conceptual models that will serve as a basis for approaching mental health from the perspective of health promotion.

  2. Rare gas systematics: Formation of the atmosphere, evolution and structure of the Earth's mantle

    International Nuclear Information System (INIS)

    Allegre, C.J.; Staudacher, T.; Sarda, P.; Paris-6 Univ., 75; Paris-7 Univ., 75

    1987-01-01

    To explain the rare gas content and isotopic composition measured in modern terrestrial materials we explore in this paper an Earth model based on four reservoirs: atmosphere, continental crust, upper mantle and lower mantle. This exploration employs three tools: mass balance equations, the concept of mean age of outgassing and the systematic use of all of the rare gases involving both absolute amount and isotopic composition. The results obtained are as follows: half of the Earth's mantle is 99% outgassed. Outgassing occurred in an early very intense stage within the first 50 Ma of Earth history and a slow continuous stage which continues to the present day. The mean age of the atmosphere is 4.4 Ga. Our model with four main reservoirs explains quantitatively both isotopic and chemical ratios, assuming that He migrates from the lower to the upper mantle whereas the heavy rare gases did not. Noble gas fluxes for He, Ar and Xe from different reservoirs have been estimated. The results constrain the K content in the earth to 278 ppm. Several geodynamic consequences are discussed. (orig.)

  3. The open abdomen and temporary abdominal closure systems--historical evolution and systematic review.

    Science.gov (United States)

    Quyn, A J; Johnston, C; Hall, D; Chambers, A; Arapova, N; Ogston, S; Amin, A I

    2012-08-01

    Several techniques for temporary abdominal closure have been developed. We systematically review the literature on temporary abdominal closure to ascertain whether the method can be tailored to the indication. Medline, Embase, the Cochrane Central Register of Controlled Trials and relevant meeting abstracts until December 2009 were searched using the following headings: open abdomen, laparostomy, VAC (vacuum assisted closure), TNP (topical negative pressure), fascial closure, temporary abdominal closure, fascial dehiscence and deep wound dehiscence. The data were analysed by closure technique and aetiology. The primary end-points included delayed fascial closure and in-hospital mortality. The secondary end-points were intra-abdominal complications. The search identified 106 papers for inclusion. The techniques described were VAC (38 series), mesh/sheet (30 series), packing (15 series), Wittmann patch (eight series), Bogotá bag (six series), dynamic retention sutures (three series), zipper (15 series), skin only and locking device (one series each). The highest facial closure rates were seen with the Wittmann patch (78%), dynamic retention sutures (71%) and VAC (61%). Temporary abdominal closure has evolved from simple packing to VAC based systems. In the absence of sepsis Wittmann patch and VAC offered the best outcome. In its presence VAC had the highest delayed primary closure and the lowest mortality rates. However, due to data heterogeneity only limited conclusions can be drawn from this analysis. © 2012 The Authors. Colorectal Disease © 2012 The Association of Coloproctology of Great Britain and Ireland.

  4. The history and evolution of the clinical effectiveness of haemophilia type a treatment: a systematic review.

    Science.gov (United States)

    Castro, Hector E; Briceño, María Fernanda; Casas, Claudia P; Rueda, Juan David

    2014-03-01

    First evidence of cases of haemophilia dates from ancient Egypt, but it was when Queen Victoria from England in the 19th century transmitted this illness to her descendants, when it became known as the "royal disease". Last decades of the 20th century account for major discoveries that improved the life expectancy and quality of life of these patients. The history and evolution of haemophilia healthcare counts ups and downs. The introduction of prophylactic schemes during the 1970s have proved to be more effective that the classic on-demand replacement of clotting factors, nevertheless many patients managed with frequent plasma transfusions or derived products became infected with the Human Immunodeficiency Virus (HIV) and Hepatitis C virus during the 1980s and 1990s. Recombinant factor VIII inception has decreased the risk of blood borne infections and restored back longer life expectancies. Main concerns for haemophilia healthcare are shifting from the pure clinical aspects to the economic considerations of long-term replacement therapy. Nowadays researchers' attention has been placed on the future costs and cost-effectiveness of costly long-term treatment. Equity considerations are relevant as well, and alternative options for less affluent countries are under the scope of further research. The aim of this review was to assess the evidence of different treatment options for haemophilia type A over the past four decades, focusing on the most important technological advances that have influenced the natural course of this "royal disease".

  5. Evolution, systematics, and phylogeography of pleistocene horses in the new world: a molecular perspective.

    Directory of Open Access Journals (Sweden)

    2005-08-01

    Full Text Available The rich fossil record of horses has made them a classic example of evolutionary processes. However, while the overall picture of equid evolution is well known, the details are surprisingly poorly understood, especially for the later Pliocene and Pleistocene, c. 3 million to 0.01 million years (Ma ago, and nowhere more so than in the Americas. There is no consensus on the number of equid species or even the number of lineages that existed in these continents. Likewise, the origin of the endemic South American genus Hippidion is unresolved, as is the phylogenetic position of the "stilt-legged" horses of North America. Using ancient DNA sequences, we show that, in contrast to current models based on morphology and a recent genetic study, Hippidion was phylogenetically close to the caballine (true horses, with origins considerably more recent than the currently accepted date of c. 10 Ma. Furthermore, we show that stilt-legged horses, commonly regarded as Old World migrants related to the hemionid asses of Asia, were in fact an endemic North American lineage. Finally, our data suggest that there were fewer horse species in late Pleistocene North America than have been named on morphological grounds. Both caballine and stilt-legged lineages may each have comprised a single, wide-ranging species.

  6. Evolution, systematics, and phylogeography of pleistocene horses in the new world: a molecular perspective.

    Science.gov (United States)

    Weinstock, Jaco; Willerslev, Eske; Sher, Andrei; Tong, Wenfei; Ho, Simon Y W; Rubenstein, Dan; Storer, John; Burns, James; Martin, Larry; Bravi, Claudio; Prieto, Alfredo; Froese, Duane; Scott, Eric; Xulong, Lai; Cooper, Alan

    2005-08-01

    The rich fossil record of horses has made them a classic example of evolutionary processes. However, while the overall picture of equid evolution is well known, the details are surprisingly poorly understood, especially for the later Pliocene and Pleistocene, c. 3 million to 0.01 million years (Ma) ago, and nowhere more so than in the Americas. There is no consensus on the number of equid species or even the number of lineages that existed in these continents. Likewise, the origin of the endemic South American genus Hippidion is unresolved, as is the phylogenetic position of the "stilt-legged" horses of North America. Using ancient DNA sequences, we show that, in contrast to current models based on morphology and a recent genetic study, Hippidion was phylogenetically close to the caballine (true) horses, with origins considerably more recent than the currently accepted date of c. 10 Ma. Furthermore, we show that stilt-legged horses, commonly regarded as Old World migrants related to the hemionid asses of Asia, were in fact an endemic North American lineage. Finally, our data suggest that there were fewer horse species in late Pleistocene North America than have been named on morphological grounds. Both caballine and stilt-legged lineages may each have comprised a single, wide-ranging species.

  7. Non-homologous isofunctional enzymes: a systematic analysis of alternative solutions in enzyme evolution.

    Science.gov (United States)

    Omelchenko, Marina V; Galperin, Michael Y; Wolf, Yuri I; Koonin, Eugene V

    2010-04-30

    Evolutionarily unrelated proteins that catalyze the same biochemical reactions are often referred to as analogous - as opposed to homologous - enzymes. The existence of numerous alternative, non-homologous enzyme isoforms presents an interesting evolutionary problem; it also complicates genome-based reconstruction of the metabolic pathways in a variety of organisms. In 1998, a systematic search for analogous enzymes resulted in the identification of 105 Enzyme Commission (EC) numbers that included two or more proteins without detectable sequence similarity to each other, including 34 EC nodes where proteins were known (or predicted) to have distinct structural folds, indicating independent evolutionary origins. In the past 12 years, many putative non-homologous isofunctional enzymes were identified in newly sequenced genomes. In addition, efforts in structural genomics resulted in a vastly improved structural coverage of proteomes, providing for definitive assessment of (non)homologous relationships between proteins. We report the results of a comprehensive search for non-homologous isofunctional enzymes (NISE) that yielded 185 EC nodes with two or more experimentally characterized - or predicted - structurally unrelated proteins. Of these NISE sets, only 74 were from the original 1998 list. Structural assignments of the NISE show over-representation of proteins with the TIM barrel fold and the nucleotide-binding Rossmann fold. From the functional perspective, the set of NISE is enriched in hydrolases, particularly carbohydrate hydrolases, and in enzymes involved in defense against oxidative stress. These results indicate that at least some of the non-homologous isofunctional enzymes were recruited relatively recently from enzyme families that are active against related substrates and are sufficiently flexible to accommodate changes in substrate specificity.

  8. Systematics and Evolution of the Miocene Three-Horned Palaeomerycid Ruminants (Mammalia, Cetartiodactyla.

    Directory of Open Access Journals (Sweden)

    Israel M Sánchez

    Full Text Available Palaeomerycids were strange three-horned Eurasian Miocene ruminants known through fossils from Spain to China. We here study their systematics, offering the first cladistic phylogeny of the best-known species of the group, and also reassess their phylogenetic position among ruminants, which is currently disputed. The beautifully preserved remains of a new palaeomerycid from middle Miocene deposits of Spain, Xenokeryx amidalae gen. et sp. nov., helps us to better understand palaeomerycid anatomy, especially that of the nuchal region in the skull, significantly improving our current knowledge on these enigmatic ruminants. Our results show two main lineages of palaeomerycids, one containing the genus Ampelomeryx diagnosed by a characteristic type of cranium / cranial appendages and some dental derived traits, and another one that clusters those forms more closely related to Triceromeryx than to Ampelomeryx, characterized by a more derived dentition and a set of apomorphic cranial features. Xenokeryx branches as a basal offshoot of this clade. Also, we find that Eurasian palaeomerycids are not closely related to North American dromomerycids, thus rejecting the currently more accepted view of palaeomerycids as the Eurasian part of the dromomerycid lineage. Instead of this, palaeomerycids are nested with the African Miocene pecoran Propalaeoryx and with giraffoids. On the other hand, dromomerycids are closely related to cervids. We define a clade Giraffomorpha that includes palaeomerycids and giraffids, and propose an emended diagnosis of the Palaeomerycidae based on cranial and postcranial characters, including several features of the cranium not described so far. We also define the Palaeomerycidae as the least inclusive clade of pecorans containing Triceromeryx and Ampelomeryx. Finally, we reassess the taxonomy of several palaeomerycid taxa.

  9. Synthesis of Ag2O nanocrystals with systematic shape evolution from cubic to hexapod structures and their surface properties.

    Science.gov (United States)

    Lyu, Lian-Ming; Wang, Wei-Ching; Huang, Michael H

    2010-12-17

    We report the development of a facile method for the synthesis of Ag(2)O crystals with systematic shape evolution from cubic to edge- and corner-truncated cubic, rhombicuboctahedral, edge- and corner-truncated octahedral, octahedral, and hexapod structures by mixing AgNO(3), NH(4)NO(3), and NaOH at molar ratios of 1:2:11.8. A sufficient volume of NaOH solution was first added to a mixture of AgNO(3) and NH(4)NO(3) solution to promote the formation of Ag(NH(3))(2)(+) complex ions and the growth of Ag(2)O nanocrystals with good morphological control. The crystals are mostly submicrometer-sized. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterization has been performed to determine the crystalline surface facets. A band gap value of approximately 1.45 eV has been found for the octahedral Ag(2)O crystals. By changing the molar ratios of AgNO(3)/NH(4)NO(3)/NaOH to 1:2:41.8, corner-depressed rhombicuboctahedra and elongated hexapods were obtained as a result of enhanced crystal growth along the [100] directions. Smaller nanocubes with average sizes of approximately 200 and 300 nm and octapods can also be prepared by adjusting the reagent molar ratios and their added volumes. Both the octahedra and hexapods with largely silver atom-terminated {111} surface facets responded repulsively and moved to the surface of the solution when dispersing in a solution of positively charged methylene blue, but can be suspended in a negatively charged methyl orange solution. The cubes and octapods, bounded by the {100} faces, were insensitive to the molecular charges in solution. The dramatic facet-dependent surface properties of Ag(2)O crystals have been demonstrated.

  10. Systematics, biogeography, and character evolution of the legume tribe Fabeae with special focus on the middle-Atlantic island lineages

    Directory of Open Access Journals (Sweden)

    Schaefer Hanno

    2012-12-01

    Full Text Available Abstract Background Tribe Fabeae comprises about 380 legume species, including some of the most ancient and important crops like lentil, pea, and broad bean. Breeding efforts in legume crops rely on a detailed knowledge of closest wild relatives and geographic origin. Relationships within the tribe, however, are incompletely known and previous molecular results conflicted with the traditional morphology-based classification. Here we analyse the systematics, biogeography, and character evolution in the tribe based on plastid and nuclear DNA sequences. Results Phylogenetic analyses including c. 70% of the species in the tribe show that the genera Vicia and Lathyrus in their current circumscription are not monophyletic: Pisum and Vavilovia are nested in Lathyrus, the genus Lens is nested in Vicia. A small, well-supported clade including Vicia hirsuta, V. sylvatica, and some Mediterranean endemics, is the sister group to all remaining species in the tribe. Fabeae originated in the East Mediterranean region in the Miocene (23–16 million years ago (Ma and spread at least 39 times into Eurasia, seven times to the Americas, twice to tropical Africa and four times to Macaronesia. Broad bean (V. faba and its sister V. paucijuga originated in Asia and might be sister to V. oroboides. Lentil (Lens culinaris ssp. culinaris is of Mediterranean origin and together with eight very close relatives forms a clade that is nested in the core Vicia, where it evolved c. 14 Ma. The Pisum clade is nested in Lathyrus in a grade with the Mediterranean L. gloeosperma, L. neurolobus, and L. nissolia. The extinct Azorean endemic V. dennesiana belongs in section Cracca and is nested among Mediterranean species. According to our ancestral character state reconstruction results, ancestors of Fabeae had a basic chromosome number of 2n=14, an annual life form, and evenly hairy, dorsiventrally compressed styles. Conclusions Fabeae evolved in the Eastern Mediterranean in the

  11. Systematics, biogeography, and character evolution of the legume tribe Fabeae with special focus on the middle-Atlantic island lineages.

    Science.gov (United States)

    Schaefer, Hanno; Hechenleitner, Paulina; Santos-Guerra, Arnoldo; Menezes de Sequeira, Miguel; Pennington, R Toby; Kenicer, Gregory; Carine, Mark A

    2012-12-25

    Tribe Fabeae comprises about 380 legume species, including some of the most ancient and important crops like lentil, pea, and broad bean. Breeding efforts in legume crops rely on a detailed knowledge of closest wild relatives and geographic origin. Relationships within the tribe, however, are incompletely known and previous molecular results conflicted with the traditional morphology-based classification. Here we analyse the systematics, biogeography, and character evolution in the tribe based on plastid and nuclear DNA sequences. Phylogenetic analyses including c. 70% of the species in the tribe show that the genera Vicia and Lathyrus in their current circumscription are not monophyletic: Pisum and Vavilovia are nested in Lathyrus, the genus Lens is nested in Vicia. A small, well-supported clade including Vicia hirsuta, V. sylvatica, and some Mediterranean endemics, is the sister group to all remaining species in the tribe. Fabeae originated in the East Mediterranean region in the Miocene (23-16 million years ago (Ma)) and spread at least 39 times into Eurasia, seven times to the Americas, twice to tropical Africa and four times to Macaronesia. Broad bean (V. faba) and its sister V. paucijuga originated in Asia and might be sister to V. oroboides. Lentil (Lens culinaris ssp. culinaris) is of Mediterranean origin and together with eight very close relatives forms a clade that is nested in the core Vicia, where it evolved c. 14 Ma. The Pisum clade is nested in Lathyrus in a grade with the Mediterranean L. gloeosperma, L. neurolobus, and L. nissolia. The extinct Azorean endemic V. dennesiana belongs in section Cracca and is nested among Mediterranean species. According to our ancestral character state reconstruction results, ancestors of Fabeae had a basic chromosome number of 2n=14, an annual life form, and evenly hairy, dorsiventrally compressed styles. Fabeae evolved in the Eastern Mediterranean in the middle Miocene and spread from there across Eurasia, into

  12. Effect of Systematic Control of Pd Thickness and Annealing Temperature on the Fabrication and Evolution of Palladium Nanostructures on Si (111) via the Solid State Dewetting.

    Science.gov (United States)

    Kunwar, Sundar; Pandey, Puran; Sui, Mao; Zhang, Quanzhen; Li, Ming-Yu; Lee, Jihoon

    2017-12-01

    Si-based optoelectronic devices embedded with metallic nanoparticles (NPs) have demonstrated the NP shape, size, spacing, and crystallinity dependent on light absorption and emission induced by the localized surface plasmon resonance. In this work, we demonstrate various sizes and configurations of palladium (Pd) nanostructures on Si (111) by the systematic thermal annealing with the variation of Pd thickness and annealing temperature. The evolution of Pd nanostructures are systematically controlled by the dewetting of thin film by means of the surface diffusion in conjunction with the surface and interface energy minimization and Volmer-Weber growth model. Depending on the control of deposition amount ranging between 0.5 and 100 nm at various annealing temperatures, four distinctive regimes of Pd nanostructures are demonstrated: (i) small pits and grain formation, (ii) nucleation and growth of NPs, (iii) lateral evolution of NPs, and (iv) merged nanostructures. In addition, by the control of annealing between 300 and 800 °C, the Pd nanostructures show the evolution of small pits and grains, isolated NPs, and finally, Pd NP-assisted nanohole formation along with the Si decomposition and Pd-Si inter-diffusion. The Raman analysis showed the discrepancies on phonon modes of Si (111) such that the decreased peak intensity with left shift after the fabrication of Pd nanostructures. Furthermore, the UV-VIS-NIR reflectance spectra revealed the existence of surface morphology dependent on absorption, scattering, and reflectance properties.

  13. Moving Evolution Education Forward: A Systematic Analysis of Literature to Identify Gaps in Collective Knowledge for Teaching

    Science.gov (United States)

    Ziadie, M. A.; Andrews, T. C.

    2018-01-01

    Evolution is a unifying theory in biology and is challenging for undergraduates to learn. An instructor's ability to help students learn is influenced by pedagogical content knowledge (PCK), which is topic-specific knowledge of teaching and learning. Instructors need PCK for every topic they teach, which is a tremendous body of knowledge to…

  14. Ocean Worlds Analog Systems in the Hadal Ocean: Systematic Examination of Pressure, Food Supply, Topography, and Evolution on Hadal Life

    Science.gov (United States)

    Shank, T. M.; German, C.; Machado, C.; Bowen, A.; Drazen, J.; Yancey, P.; Jamieson, A.; Rowden, A.; Clark, M.; Heyl, T.; Mayor, D.; Piertney, S.; Ruhl, H.

    2018-05-01

    Key questions on life’s evolution are being pursued in Earth’s hadal ocean, Earth’s only analog to Europa’s ocean. A recent WHOI-JPL partnership is developing an armada of autonomous underwater drone vehicles to explore of Earth’s and Europa’s oceans.

  15. Studies of uranium-lead systematics by volatilization and the evolution of the Yellowknife area, N.W.T

    International Nuclear Information System (INIS)

    Tsong, C.-F.F.

    1974-01-01

    Studies of uranium-lead systematics in eight plutonic rocks indicate that the western granodiorite which intrudes the Yellowknife volcanics has whole rock and mineral isochron ages of 2700 +- 85 m.y. and 2550 +- 70 m.y. respectively. Some new sulfide and galena data from the Yellowknife volcanics and the sediments suggest a mineralization age of close to 2630 m.y.. (author)

  16. Direct evidence for a systematic evolution of optical band gap and local disorder in Ag, in doped Sb{sub 2}Te phase change material

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Krishna Dayal; Sahu, Smriti [Discipline of Electrical Engineering, Indian Institute of Technology Indore (India); Manivannan, Anbarasu [Discipline of Electrical Engineering, Indian Institute of Technology Indore (India); Metallurgical Engineering and Materials Science, Indian Institute of Technology Indore, Indore (India); Deshpande, Uday Prabhakarrao [UGC-DAE Consortium for Scientific Research, Indore (India)

    2017-12-15

    Rapid and reversible switching properties of Ag, In doped Sb{sub 2}Te (AIST) phase change material is widely used in re-writable optical data storage applications. We report here a systematic evolution of optical band gap (E{sub g}), local disorder (Tauc parameter, β), and Urbach energy (E{sub U}) of AIST material during amorphous to crystalline transition using in situ UV-Vis-NIR spectroscopy. Unlike GeTe-Sb{sub 2}Te{sub 3} (GST) family, AIST material is found to show unique characteristics as evidenced by the presence of direct forbidden transitions. Crystallization is accompanied by a systematic reduction in E{sub g} from 0.50 eV (as-deposited amorphous at 300 K) to 0.18 eV (crystalline at 300 K). Moreover, decrease in E{sub U} (from 272 to 212 meV) and β is also observed during increasing the temperature in the amorphous phase, revealing direct observation of enhancement of the medium-range order and distortion in short range order, respectively. These findings of optical transition would be helpful for distinguishing the unique behavior of AIST material from GST family. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Floral organ MADS-box genes in Cercidiphyllum japonicum (Cercidiphyllaceae: Implications for systematic evolution and bracts definition.

    Directory of Open Access Journals (Sweden)

    Yupei Jin

    Full Text Available The dioecious relic Cercidiphyllum japonicum is one of two species of the sole genus Cercidiphyllum, with a tight inflorescence lacking an apparent perianth structure. In addition, its systematic place has been much debated and, so far researches have mainly focused on its morphology and chloroplast genes. In our investigation, we identified 10 floral organ identity genes, including four A-class, three B-class, two C-class and one D-class. Phylogenetic analyses showed that all ten genes are grouped with Saxifragales plants, which confirmed the phylogenetic place of C. japonicum. Expression patterns of those genes were examined by quantitative reverse transcriptase PCR, with some variations that did not completely coincide with the ABCDE model, suggesting some subfunctionalization. As well, our research supported the idea that thebract actually is perianth according to our morphological and molecular analyses in Cercidiphyllum japonicum.

  18. Floral organ MADS-box genes in Cercidiphyllum japonicum (Cercidiphyllaceae): Implications for systematic evolution and bracts definition.

    Science.gov (United States)

    Jin, Yupei; Wang, Yubing; Zhang, Dechun; Shen, Xiangling; Liu, Wen; Chen, Faju

    2017-01-01

    The dioecious relic Cercidiphyllum japonicum is one of two species of the sole genus Cercidiphyllum, with a tight inflorescence lacking an apparent perianth structure. In addition, its systematic place has been much debated and, so far researches have mainly focused on its morphology and chloroplast genes. In our investigation, we identified 10 floral organ identity genes, including four A-class, three B-class, two C-class and one D-class. Phylogenetic analyses showed that all ten genes are grouped with Saxifragales plants, which confirmed the phylogenetic place of C. japonicum. Expression patterns of those genes were examined by quantitative reverse transcriptase PCR, with some variations that did not completely coincide with the ABCDE model, suggesting some subfunctionalization. As well, our research supported the idea that thebract actually is perianth according to our morphological and molecular analyses in Cercidiphyllum japonicum.

  19. Tracking seasonal subglacial drainage evolution of alpine glaciers using radiogenic Nd and Sr isotope systematics: Lemon Creek Glacier, Alaska

    Science.gov (United States)

    Clinger, A. E.; Aciego, S.; Stevenson, E. I.; Arendt, C. A.

    2014-12-01

    The transport pathways of water beneath a glacier are subject to change as melt seasons progress due to variability in the balance between basal water pressure and water flux. Subglacial hydrology has been well studied, but the understanding of spatial distribution is less well constrained. Whereas radiogenic isotopic tracers have been traditionally used as proxies to track spatial variability and weathering rates in fluvial and riverine systems, these techniques have yet to be applied extensively to the subglacial environment and may help resolve ambiguity in subglacial hydrology. Research has shown the 143Nd/144Nd values can reflect variation in source provenance processes due to variations in the age of the continental crust. Correlating the 143Nd/144Nd with other radiogenic isotope systematics such as strontium (87Sr/86Sr) provides important constraints on the role of congruent and incongruent weathering processes. Our study presents the application of Nd and Sr systematics using isotopic ratios to the suspended load of subglacial meltwater collected over a single melt season at Lemon Creek Glacier, USA (LCG). The time-series data show an average ɛNd ~ -6.83, indicating a young bedrock (~60 MYA). Isotopic variation helps track the seasonal expansion of the subglacial meltwater channels and subsequent return to early season conditions due to the parabolic trend towards less radiogenic Nd in June and towards more radiogenic Nd beginning in mid-August. However, the high variability in July and early August may reflect a mixture of source as the channels diverge and derive sediment from differently aged lithologies. We find a poor correlation between 143Nd/144Nd and 87Sr/86Sr (R2= 0.38) along with a slight trend towards more radiogenic 87Sr/86Sr values with time ((R2= 0.49). This may indicate that, even as the residence time decreases over the melt season, the LCG subglacial system is relatively stable and that the bedrock is congruently weathered. Our study

  20. Magmatic evolution of a volcano studied by 230Th-238U disequilibrium and trace elements systematics: the Etna case

    International Nuclear Information System (INIS)

    Condomines, M.; Allegre, C.J.; Tanguy, J.C.; Kieffer, G.

    1982-01-01

    Age determinations of several lava flows from Etna through 230 Th- 238 U disequilibrium (internal isochrons) yield a precise chronology of the volcano's history for the last 200,000 years, and emphasize the main episodes in the formation of this huge complex strato-volcano. Study of ( 230 Th/ 232 Th) 0 initial ratios of lavas together with their trace-element compositions yields a consistent model of magmatic evolution implying the existence, for 200,000 years, of a deep reservoir of alkalic magma periodically mixed with magmas of tholeiitic affinity. These short periods of mixing appear to be related to the formation of the large calderas of Etna. In addition to these processes affecting the deep reservoir, fractional crystallization also occurred in more superficial levels of the volcanic edifice, thereby yielding several series of differentiation of relatively short duration. As for its geochemistry, Etna's volcanism is of oceanic type but with its own characteristics and in a peculiar geodynamic context, at the edge of the African Plate. (author)

  1. Systematics and evolution of the Meriones shawii/grandis complex (Rodentia, Gerbillinae) during the Late Quaternary in northwestern Africa: Exploring the role of environmental and anthropogenic changes

    Science.gov (United States)

    Stoetzel, Emmanuelle; Cornette, Raphaël; Lalis, Aude; Nicolas, Violaine; Cucchi, Thomas; Denys, Christiane

    2017-05-01

    Rodents of the Meriones shawii/grandis complex have been attested to in North Africa since the Middle Pleistocene and are abundant in archaeological sites. Today, they are widely spread and represent a major pest to local human populations. This complex, therefore, represents an accurate model for investigating the roles of climate change and human impact in shaping Quaternary faunal diversity and distribution. Many gray areas still exist regarding the systematics, ecology and geographical distribution of this complex, for both present and past populations. The purpose of this study is to compare modern genotyped and fossil Meriones specimens in order to 1) clarify the current systematics and distribution of the Meriones populations of the shawii/grandis complex, 2) document the taxonomic diversity in fossil Meriones from northwestern Africa, and 3) track their phenotypic and biogeographic evolution through time. To answer these questions we used geometric morphometrics on skulls (landmarks) and first upper molars (landmarks and sliding landmarks). We evidenced the existence of two morpho-groups within the M. shawii/grandis complex, with a clear geographic pattern (M. grandis in Morocco vs. M. shawii in Algeria and Tunisia). Currently only one morpho-group, attributed to M. grandis, seems to exist in Morocco, with a small overlap with M. shawii in the most eastern part of the country. However, according to fossil data, M. shawii was also present in Atlantic Morocco during the Late Pleistocene. We have also highlighted the impact of Holocene climate change and habitat anthropization on this arid adapted group. During the Middle Holocene, a major climatic event (last interglacial optimum) seems to have induced a demographic collapse in Moroccan populations and the disappearance of the shawii clade from Morocco (except in the most eastern areas). Both species then re-expanded, benefitting from the increasing aridity and the new ecological niche driven by agriculture

  2. Investigation on the morphological and optical evolution of bimetallic Pd-Ag nanoparticles on sapphire (0001) by the systematic control of composition, annealing temperature and time.

    Science.gov (United States)

    Pandey, Puran; Kunwar, Sundar; Sui, Mao; Bastola, Sushil; Lee, Jihoon

    2017-01-01

    Multi-metallic alloy nanoparticles (NPs) can offer additional opportunities for modifying the electronic, optical and catalytic properties by the control of composition, configuration and size of individual nanostructures that are consisted of more than single element. In this paper, the fabrication of bimetallic Pd-Ag NPs is systematically demonstrated via the solid state dewetting of bilayer thin films on c-plane sapphire by governing the temperature, time as well as composition. The composition of Pd-Ag bilayer remarkably affects the morphology of alloy nanostructures, in which the higher Ag composition, i.e. Pd0.25Ag0.75, leads to the enhanced dewetting of bilayers whereas the higher Pd composition (Pd0.75Ag0.25) hinders the dewetting. Depending on the annealing temperature, Pd-Ag alloy nanostructures evolve with a series of configurations, i.e. nucleation of voids, porous network, elongated nanoclusters and round alloy NPs. In addition, with the annealing time set, the gradual configuration transformation from the elongated to round alloy NPs as well as size reduction is demonstrated due to the enhanced diffusion and sublimation of Ag atoms. The evolution of various morphology of Pd-Ag nanostructures is described based on the surface diffusion and inter-diffusion of Pd and Ag adatoms along with the Ag sublimation, Rayleigh instability and energy minimization mechanism. The reflectance spectra of bimetallic Pd-Ag nanostructures exhibit various quadrupolar and dipolar resonance peaks, peak shifts and absorption dips owing to the surface plasmon resonance of nanostructures depending on the surface morphology. The intensity of reflectance spectra is gradually decreased along with the surface coverage and NP size evolution. The absorption dips are red-shifted towards the longer wavelength for the larger alloy NPs and vice-versa.

  3. Investigation on the morphological and optical evolution of bimetallic Pd-Ag nanoparticles on sapphire (0001 by the systematic control of composition, annealing temperature and time.

    Directory of Open Access Journals (Sweden)

    Puran Pandey

    Full Text Available Multi-metallic alloy nanoparticles (NPs can offer additional opportunities for modifying the electronic, optical and catalytic properties by the control of composition, configuration and size of individual nanostructures that are consisted of more than single element. In this paper, the fabrication of bimetallic Pd-Ag NPs is systematically demonstrated via the solid state dewetting of bilayer thin films on c-plane sapphire by governing the temperature, time as well as composition. The composition of Pd-Ag bilayer remarkably affects the morphology of alloy nanostructures, in which the higher Ag composition, i.e. Pd0.25Ag0.75, leads to the enhanced dewetting of bilayers whereas the higher Pd composition (Pd0.75Ag0.25 hinders the dewetting. Depending on the annealing temperature, Pd-Ag alloy nanostructures evolve with a series of configurations, i.e. nucleation of voids, porous network, elongated nanoclusters and round alloy NPs. In addition, with the annealing time set, the gradual configuration transformation from the elongated to round alloy NPs as well as size reduction is demonstrated due to the enhanced diffusion and sublimation of Ag atoms. The evolution of various morphology of Pd-Ag nanostructures is described based on the surface diffusion and inter-diffusion of Pd and Ag adatoms along with the Ag sublimation, Rayleigh instability and energy minimization mechanism. The reflectance spectra of bimetallic Pd-Ag nanostructures exhibit various quadrupolar and dipolar resonance peaks, peak shifts and absorption dips owing to the surface plasmon resonance of nanostructures depending on the surface morphology. The intensity of reflectance spectra is gradually decreased along with the surface coverage and NP size evolution. The absorption dips are red-shifted towards the longer wavelength for the larger alloy NPs and vice-versa.

  4. An updated systematic review of the evolution of ALPPS and evaluation of its advantages and disadvantages in accordance with current evidence.

    Science.gov (United States)

    Cai, Yu-Long; Song, Pei-Pei; Tang, Wei; Cheng, Nan-Sheng

    2016-06-01

    The main obstacle to achieving an R0 resection after a major hepatectomy is inability to preserve an adequate future liver remnant (FLR) to avoid postoperative liver failure (PLF). Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a novel technique for resecting tumors that were previously considered unresectable, and this technique results in a vast increase in the volume of the FLR in a short period of time. However, this technique continues to provoke heated debate because of its high mortality and morbidity.The evolution of ALPPS and its advantages and disadvantages have been systematically reviewed and evaluated in accordance with current evidence. Electronic databases (PubMed and Medline) were searched for potentially relevant articles from January 2007 to January 2016.ALPPS has evolved into various modified forms. Some of these modified techniques have reduced the difficulty of the procedure and enhanced its safety. Current evidence indicates that the advantages of ALPPS are rapid hypertrophy of the FLR, the feasibility of the procedure, and a higher rate of R0 resection in comparison to other techniques. However, ALPPS is associated with worse major complications, more deaths, and early tumor recurrence.Hepatobiliary surgeons should carefully consider whether to perform ALPPS. Some modified forms of ALPPS have reduced the mortality and morbidity of the procedure, but they cannot be recommended over the original procedure currently. Portal vein embolization (PVE) is still the procedure of choice for patients with a tumor-free FLR, and ALPPS could be used as a salvage procedure when PVE fails. More persuasive evidence needs to be assembled to determine whether ALPPS or two-stage hepatectomy (TSH) is better for patients with a tumor involving the FLR. Evidence with regard to long-term oncological outcomes is still limited. More meticulous comparative studies and studies of the 5-year survival rate of ALPPS could ultimately

  5. U-Pb isotope systematics and compared evolution of uraniferous mineralizations in the Athabasca basin (Saskatchewan, Canada): Case of deposits from the Carswell and Cigar Lake structure

    International Nuclear Information System (INIS)

    Philippe, S.

    1988-01-01

    The aim of the study is to obtain geochronologic data on the formation of mineralizations, to define main processes for uranium remobilization and to replace these data in proposed model for deposit genesis and evolution [fr

  6. Lead-lead systematics, the 'age of the earth' and the chemical evolution of our planet in a new representation space

    International Nuclear Information System (INIS)

    Manhes, G.; Allegre, C.J.; Dupre, B.; Hamelin, B.

    1979-01-01

    A new way to look at the Pb-Pb isotopic results is proposed. The characteristics are as follows: (1) knowledge of the initial ratios of cogenetic samples is not necessary to discuss the isotopic evolution of parent bodies; and (2) linear representations are permissible thus allowing for a simplified treatment in comparison to the classical 206 Pb/ 204 Pb vs. 207 Pb/ 204 Pb diagram. Using Pb-Pb data of terrestrial samples, either stated in past reasearch or as recently measured by the laboratory, problems such as the Earth's age and its evolution are being dealt with utilising this new formalism. The treatment for a set of mantle whole-rock measurements, assuming only the initial isotopic composition furnishes a value for the Earth's age of 4.49 +- 0.17 b.y. (Auth.)

  7. Student Visual Communication of Evolution

    Science.gov (United States)

    Oliveira, Alandeom W.; Cook, Kristin

    2017-01-01

    Despite growing recognition of the importance of visual representations to science education, previous research has given attention mostly to verbal modalities of evolution instruction. Visual aspects of classroom learning of evolution are yet to be systematically examined by science educators. The present study attends to this issue by exploring…

  8. Carbon isotope systematics of the Cambrian–Vendian aquifer system in the northern Baltic Basin: Implications to the age and evolution of groundwater

    International Nuclear Information System (INIS)

    Raidla, Valle; Kirsimäe, Kalle; Vaikmäe, Rein; Kaup, Enn; Martma, Tõnu

    2012-01-01

    Groundwater in the Cambrian–Vendian aquifer system has a strongly depleted stable isotope composition (δ 18 O values of about −22‰) and a low radiocarbon concentration, which suggests that the water is of glacial origin from the last Ice Age. The aim of this paper was to elucidate the timing of infiltration of glacial waters and to understand the geochemical evolution of this groundwater. The composition of the dissolved inorganic C (DIC) in Cambrian–Vendian groundwater is influenced by complex reactions and isotope exchange processes between water, organic materials and rock matrix. The δ 13 C composition of dissolved inorganic C in Cambrian–Vendian water also indicates a bacterial modification of the isotope system. The corrected radiocarbon ages of groundwater are between 14,000 and 27,000 radiocarbon years, which is coeval with the advance of the Weichselian Glacier in the area.

  9. Systematic Identification, Evolution and Expression Analysis of the Zea mays PHT1 Gene Family Reveals Several New Members Involved in Root Colonization by Arbuscular Mycorrhizal Fungi.

    Science.gov (United States)

    Liu, Fang; Xu, Yunjian; Jiang, Huanhuan; Jiang, Chaosheng; Du, Yibin; Gong, Cheng; Wang, Wei; Zhu, Suwen; Han, Guomin; Cheng, Beijiu

    2016-06-13

    The Phosphate Transporter1 (PHT1) family of genes plays pivotal roles in the uptake of inorganic phosphate from soils. However, there is no comprehensive report on the PHT1 family in Zea mays based on the whole genome. In the present study, a total of 13 putative PHT1 genes (ZmPHT1;1 to 13) were identified in the inbred line B73 genome by bioinformatics methods. Then, their function was investigated by a yeast PHO84 mutant complementary experiment and qRT-PCR. Thirteen ZmPHT1 genes distributed on six chromosomes (1, 2, 5, 7, 8 and 10) were divided into two paralogues (Class A and Class B). ZmPHT1;1/ZmPHT1;9 and ZmPHT1;9/ZmPHT1;13 are produced from recent segmental duplication events. ZmPHT1;1/ZmPHT1;13 and ZmPHT1;8/ZmPHT1;10 are produced from early segmental duplication events. All 13 putative ZmPHT1s can completely or partly complement the yeast Pi-uptake mutant, and they were obviously induced in maize under low Pi conditions, except for ZmPHT1;1 (p < 0.01), indicating that the overwhelming majority of ZmPHT1 genes can respond to a low Pi condition. ZmPHT1;2, ZmPHT1;4, ZmPHT1;6, ZmPHT1;7, ZmPHT1;9 and ZmPHT1;11 were up-regulated by arbuscular mycorrhizal fungi (AMF), implying that these genes might participate in mediating Pi absorption and/or transport. Analysis of the promoters revealed that the MYCS and P1BS element are widely distributed on the region of different AMF-inducible ZmPHT1 promoters. In light of the above results, five of 13 ZmPHT1 genes were newly-identified AMF-inducible high-affinity phosphate transporters in the maize genome. Our results will lay a foundation for better understanding the PHT1 family evolution and the molecular mechanisms of inorganic phosphate transport under AMF inoculation.

  10. Student Visual Communication of Evolution

    Science.gov (United States)

    Oliveira, Alandeom W.; Cook, Kristin

    2017-06-01

    Despite growing recognition of the importance of visual representations to science education, previous research has given attention mostly to verbal modalities of evolution instruction. Visual aspects of classroom learning of evolution are yet to be systematically examined by science educators. The present study attends to this issue by exploring the types of evolutionary imagery deployed by secondary students. Our visual design analysis revealed that students resorted to two larger categories of images when visually communicating evolution: spatial metaphors (images that provided a spatio-temporal account of human evolution as a metaphorical "walk" across time and space) and symbolic representations ("icons of evolution" such as personal portraits of Charles Darwin that simply evoked evolutionary theory rather than metaphorically conveying its conceptual contents). It is argued that students need opportunities to collaboratively critique evolutionary imagery and to extend their visual perception of evolution beyond dominant images.

  11. Urban Evolution: the Role of Water

    Science.gov (United States)

    The structure, function, and services of urban ecosystems evolve over time scales from seconds to centuries as Earth's population grows, infrastructure ages, and sociopolitical values alter them. In order to systematically study changes over time, the concept of "urban evolution...

  12. Using Aptamers for Cancer Biomarker Discovery

    Directory of Open Access Journals (Sweden)

    Yun Min Chang

    2013-01-01

    Full Text Available Aptamers are single-stranded synthetic DNA- or RNA-based oligonucleotides that fold into various shapes to bind to a specific target, which includes proteins, metals, and molecules. Aptamers have high affinity and high specificity that are comparable to that of antibodies. They are obtained using iterative method, called (Systematic Evolution of Ligands by Exponential Enrichment SELEX and cell-based SELEX (cell-SELEX. Aptamers can be paired with recent advances in nanotechnology, microarray, microfluidics, and other technologies for applications in clinical medicine. One particular area that aptamers can shed a light on is biomarker discovery. Biomarkers are important in diagnosis and treatment of cancer. In this paper, we will describe ways in which aptamers can be used to discover biomarkers for cancer diagnosis and therapeutics.

  13. Fungal Systematics and Evolution: FUSE 3

    NARCIS (Netherlands)

    Krisai-Greilhuber, Irmgard; Chen, Yun; Jabeen, Sana; Madrid, Hugo; Marincowitz, Seonju; Razaq, Abdul; Sevcíková, Hana; Voglmayr, Hermann; Yazici, Kenan; Aptroot, André; Aslan, Ali; Boekhout, T.; Borovicka, Jan; Crous, P.W.; Ilyas, Sobia; Jami, Fahimeh; Jiang, Yu-Lan; Nasir Khalid, Abdul; Kolecka, Anna; Konvalinková, Tereza; Norphanphoun, Chada; Shaheen, Shabnum; Wang, Yong; Wingfield, Michael J.; Wu, Shi-Ping; Wu, Yue-Ming; Yu, Jie-Ying

    2017-01-01

    The present study introduces seven new species, one new combination, one new variety and several interesting taxonomical notes and/or geographical records. Most of the new taxa are Ascomycetes, but the study also includes a new variety of a Basidiomycete. Novel species include Gyromitra

  14. Fungal Systematics and Evolution: FUSE 2

    NARCIS (Netherlands)

    Hernández-Restrepo, Margarita; Schumacher, René K.; Wingfield, Michael J.; Ahmad, Ishtiaq; Cai, Lei; Duong, Tuan A.; Edwards, Jacqueline; Gené, Josepa; Groenewald, Johannes Z.; Jabeen, Sana; Nasir Khalid, Abdul; Lombard, Lorenzo; Madrid, Hugo; Marin-Felix, Yasmina; Marincowitz, Seonju; Miller, Andrew N.; Rajeshkumar, Kunhiraman C.; Rashid, Abdul; Sarwar, Samina; Stchigel, Alberto M.; Taylor, Paul W.J.; Zhou, Nan; Crous, Pedro W.

    2016-01-01

    The present study introduces two new genera, 14 new species, five new combinations and 12 interesting host and/or geographical records. A majority of the fungi are Ascomycetes, but the study also includes a Basidiomycete, Xerocomellus fulvus described from Pakistan. Under single name nomenclature

  15. The theory of evolution

    Directory of Open Access Journals (Sweden)

    Oleg Bazaluk

    2015-06-01

    Full Text Available The book The Theory of Evolution: from the Space Vacuum to Neural Ensembles and Moving Forward, an edition of 100 copies, was published in Russian language, in December 2014 in Kiev. Its Russian version is here: http://en.bazaluk.com/journals.html. Introduction, Chapter 10 and Conclusion published in English for the first time. Since 2004 author have been researching in the field of theory of Evolution, Big History. The book was written on the base of analysis of more than 2000 primary sources of this research topic. The volume is 90,000 words (with Reference. The book is for a wide range of professionals, from students to professors and researchers working in the fields of: philosophical anthropology, philosophy, Big History, cosmology, biology, neuroscience and etc. In the book, the author defines the evolution as continuous and nonlinear complication of the structure of matter, the types of interaction and environments; analyzes existing in modern science and philosophy approaches to the research of the process of evolution, degree of development of the factors and causes of evolution. Unifying interdisciplinary researches of evolution in cosmology, biology, neuroscience and philosophy, the author presents his vision of the model of «Evolving Matter», which allows us to consider not only the laws of transition of space vacuum in neural ensembles but also to see our Universe as a complication, heterogeneous organization. Interdisciplinary amount of information on the theory of evolution is systematized and a new method of world perception is proposed in the book.

  16. A Constructive Approach To Software Evolution

    NARCIS (Netherlands)

    Ciraci, S.; van den Broek, P.M.; Aksit, Mehmet

    2007-01-01

    In many software design and evaluation techniques, either the software evolution problem is not systematically elaborated, or only the impact of evolution is considered. Thus, most of the time software is changed by editing the components of the software system, i.e. breaking down the software

  17. Schumpeter's Evolution

    DEFF Research Database (Denmark)

    Andersen, Esben Sloth

    reworking of his basic theory of economic evolution in Development from 1934, and this reworking was continued in Cycles from 1939. Here Schumpeter also tried to handle the statistical and historical evidence on the waveform evolution of the capitalist economy. Capitalism from 1942 modified the model...

  18. Galactic evolution

    International Nuclear Information System (INIS)

    Pagel, B.

    1979-01-01

    Ideas are considered concerning the evolution of galaxies which are closely related to those of stellar evolution and the origin of elements. Using information obtained from stellar spectra, astronomers are now able to consider an underlying process to explain the distribution of various elements in the stars, gas and dust clouds of the galaxies. (U.K.)

  19. Darwinian evolution

    NARCIS (Netherlands)

    Jagers op Akkerhuis, Gerard A.J.M.; Spijkerboer, Hendrik Pieter; Koelewijn, Hans Peter

    2016-01-01

    Darwinian evolution is a central tenet in biology. Conventionally, the defi nition of Darwinian evolution is linked to a population-based process that can be measured by focusing on changes in DNA/allele frequencies. However, in some publications it has been suggested that selection represents a

  20. Managing Software Process Evolution

    DEFF Research Database (Denmark)

    This book focuses on the design, development, management, governance and application of evolving software processes that are aligned with changing business objectives, such as expansion to new domains or shifting to global production. In the context of an evolving business world, it examines...... the complete software process lifecycle, from the initial definition of a product to its systematic improvement. In doing so, it addresses difficult problems, such as how to implement processes in highly regulated domains or where to find a suitable notation system for documenting processes, and provides...... essential insights and tips to help readers manage process evolutions. And last but not least, it provides a wealth of examples and cases on how to deal with software evolution in practice. Reflecting these topics, the book is divided into three parts. Part 1 focuses on software business transformation...

  1. Stellar evolution

    CERN Document Server

    Meadows, A J

    2013-01-01

    Stellar Evolution, Second Edition covers the significant advances in the understanding of birth, life, and death of stars.This book is divided into nine chapters and begins with a description of the characteristics of stars according to their brightness, distance, size, mass, age, and chemical composition. The next chapters deal with the families, structure, and birth of stars. These topics are followed by discussions of the chemical composition and the evolution of main-sequence stars. A chapter focuses on the unique features of the sun as a star, including its evolution, magnetic fields, act

  2. Systematic review

    DEFF Research Database (Denmark)

    Enggaard, Helle

    Title: Systematic review a method to promote nursing students skills in Evidence Based Practice Background: Department of nursing educate students to practice Evidence Based Practice (EBP), where clinical decisions is based on the best available evidence, patient preference, clinical experience...... and resources available. In order to incorporate evidence in clinical decisions, nursing students need to learn how to transfer knowledge in order to utilize evidence in clinical decisions. The method of systematic review can be one approach to achieve this in nursing education. Method: As an associate lecturer...... I have taken a Comprehensive Systematic Review Training course provide by Center of Clinical Guidelines in Denmark and Jonna Briggs Institute (JBI) and practice in developing a systematic review on how patients with ischemic heart disease experiences peer support. This insight and experience...

  3. Animal evolution

    DEFF Research Database (Denmark)

    Nielsen, Claus

    This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from studies using immune stainings of nerves and muscles and blastomere markings, which makes it possi......This book provides a comprehensive analysis of evolution in the animal kingdom. It reviews the classical, morphological information from structure and embryology, as well as the new data gained from studies using immune stainings of nerves and muscles and blastomere markings, which makes...

  4. The systematics and independent evolution of cave ecomorphology in distantly related clades of Bent-toed Geckos (Genus Cyrtodactylus Gray, 1827) from the Mekong Delta and islands in the Gulf of Thailand.

    Science.gov (United States)

    Grismer, L Lee; Wood, P L Jr; Tri, Ngo Van; Murdoch, Matthew L

    2015-06-26

    An integrative taxonomic analysis of the distantly related Cyrtodactylus condorensis and intermedius species complexes of the Mekong Delta revealed that C. paradoxus is a junior synonym of C. condorensis and that C. thochuensis is a junior synonym of C. leegrismeri. Additionally, the analysis revealed that a cave-dwelling ecomorpholgy has evolved independently early on in the evolution of both complexes (represented by C. hontreensis in the intermedius complex and C. grismeri and C. eisenmani in the condorensis complex) and cave ecomorphs exist in sympatry-but not syntopy-with general scansorial ecomorphs. Multiple, recent, cyclical, glacioeustatic driven changes in sea levels across the Sunda Shelf are hypothesized to account for the evolution and distribution of the widely separated, conspecific insular populations of C. condorensis and C. leegrismeri. The independent evolution of cave ecomorphology is proposed to have been driven by competition avoidance. Habitat islands across the Mekong Delta are an important source of endemism and in need of protection.

  5. Representing Evolution

    DEFF Research Database (Denmark)

    Hedin, Gry

    2012-01-01

    . This article discusses Willumsen's etching in the context of evolutionary theory, arguing that Willumsen is a rare example of an artist who not only let the theory of evolution fuel his artistic imagination, but also concerned himself with a core issue of the theory, namely to what extent it could be applied...

  6. Security Evolution.

    Science.gov (United States)

    De Patta, Joe

    2003-01-01

    Examines how to evaluate school security, begin making schools safe, secure schools without turning them into fortresses, and secure schools easily and affordably; the evolution of security systems into information technology systems; using schools' high-speed network lines; how one specific security system was developed; pros and cons of the…

  7. Cepheid evolution

    International Nuclear Information System (INIS)

    Becker, S.A.

    1984-05-01

    A review of the phases of stellar evolution relevant to Cepheid variables of both Types I and II is presented. Type I Cepheids arise as a result of normal post-main sequence evolutionary behavior of many stars in the intermediate to massive range of stellar masses. In contrast, Type II Cepheids generally originate from low-mass stars of low metalicity which are undergoing post core helium-burning evolution. Despite great progress in the past two decades, uncertainties still remain in such areas as how to best model convective overshoot, semiconvection, stellar atmospheres, rotation, and binary evolution as well as uncertainties in important physical parameters such as the nuclear reaction rates, opacity, and mass loss rates. The potential effect of these uncertainties on stellar evolution models is discussed. Finally, comparisons between theoretical predictions and observations of Cepheid variables are presented for a number of cases. The results of these comparisons show both areas of agreement and disagreement with the latter result providing incentive for further research

  8. Venom Evolution

    Indian Academy of Sciences (India)

    IAS Admin

    Therefore, the platypus sequence was studied to quantify the role of gene duplication in the evolution of venom. ... Platypus venom is present only in males and is used for asserting dominance over com- petitors during the ... Certain toxin gene families are known to re- peatedly evolve through gene duplications. The rapidly ...

  9. Reversible evolution of charged ergoregions

    Energy Technology Data Exchange (ETDEWEB)

    Kokkotas, K.; Spyrou, N.

    1987-07-01

    The reversible evolution of a charged rotating ergoregion, due to the injection into it of particles with mass-energy and angular momentum, is studied systematically. As in the uncharged case, a bulge always forms on the outer boundary of the ergoregion due to the latter's angular momentum. The behavior of the bulge's position, relative to the black hole's rotation axis and equatorial plane, is studied, on the basis of the cosmic censorship hypothesis, during the ergoregion's reversible evolution. The range of the permitted values of the ergoregion's linear dimensions along the rotation axis and perpendicular to it is specified. Finally the differences with the evolution of an uncharged ergoregion are pointed out and discussed.

  10. Systematic review

    DEFF Research Database (Denmark)

    Lødrup, Anders Bergh; Reimer, Christina; Bytzer, Peter

    2013-01-01

    in getting off acid-suppressive medication and partly explain the increase in long-term use of PPI. A number of studies addressing this issue have been published recently. The authors aimed to systematically review the existing evidence of clinically relevant symptoms caused by acid rebound following PPI...

  11. Systematic review

    DEFF Research Database (Denmark)

    Christensen, Troels Dreier; Spindler, Karen-Lise Garm; Palshof, Jesper Andreas

    2016-01-01

    to earlier diagnosis and improved survival. Method: In this paper, we describe the incidence as well as characteristics associated with BM based on a systematic review of the current literature, following the PRISMA guidelines. Results: We show that the incidence of BM in CRC patients ranges from 0.6 to 3...

  12. Nudging Evolution?

    OpenAIRE

    Katharine N. Farrell; Andreas Thiel

    2013-01-01

    This Special Feature, "Nudging Evolution? Critical Exploration of the Potential and Limitations of the Concept of Institutional Fit for the Study and Adaptive Management of Social-Ecological Systems," aims to contribute toward the development of social theory and social research methods for the study of social-ecological system dynamics. Our objective is to help strengthen the academic discourse concerning if, and if so, how, to what extent, and in what concrete ways the concept of institut...

  13. Community Evolution

    OpenAIRE

    Saganowski, Stanisław; Bródka, Piotr; Kazienko, Przemysław

    2016-01-01

    The continuous interest in the social network area contributes to the fast development of this field. The new possibilities of obtaining and storing data facilitate deeper analysis of the entire social network, extracted social groups and single individuals as well. One of the most interesting research topic is the network dynamics and dynamics of social groups in particular, it means analysis of group evolution over time. It is the natural step forward after social community extraction. Havi...

  14. In Vitro Selection of Single-Stranded DNA Molecular Recognition Elements against S. aureus Alpha Toxin and Sensitive Detection in Human Serum

    OpenAIRE

    Hong, Ka L.; Battistella, Luisa; Salva, Alysia D.; Williams, Ryan M.; Sooter, Letha J.

    2015-01-01

    Alpha toxin is one of the major virulence factors secreted by Staphylococcus aureus, a bacterium that is responsible for a wide variety of infections in both community and hospital settings. Due to the prevalence of S. aureus related infections and the emergence of methicillin-resistant S. aureus, rapid and accurate diagnosis of S. aureus infections is crucial in benefiting patient health outcomes. In this study, a rigorous Systematic Evolution of Ligands by Exponential Enrichment (SELEX) var...

  15. The evolution of scientific views on strategic financial planning abroad

    Directory of Open Access Journals (Sweden)

    Vorobyev Alexey Vyacheslavovich

    2012-09-01

    Full Text Available This article deals with the genesis of scientific views on strategic financial planning abroad. The allocation process of strategic planning of functional strategies, particularly financial. Given the systematization of conceptual approaches to strategic financial planning within evolution.

  16. The evolution of scientific views on strategic financial planning abroad

    OpenAIRE

    Vorobyev Alexey Vyacheslavovich

    2012-01-01

    This article deals with the genesis of scientific views on strategic financial planning abroad. The allocation process of strategic planning of functional strategies, particularly financial. Given the systematization of conceptual approaches to strategic financial planning within evolution.

  17. Raptors and primate evolution.

    Science.gov (United States)

    McGraw, W Scott; Berger, Lee R

    2013-01-01

    Most scholars agree that avoiding predators is a central concern of lemurs, monkeys, and apes. However, given uncertainties about the frequency with which primates actually become prey, the selective importance of predation in primate evolution continues to be debated. Some argue that primates are often killed by predators, while others maintain that such events are relatively rare. Some authors have contended that predation's influence on primate sociality has been trivial; others counter that predation need not occur often to be a powerful selective force. Given the challenges of documenting events that can be ephemeral and irregular, we are unlikely ever to amass the volume of systematic, comparative data we have on such topics as feeding, social dynamics, or locomotor behavior. Nevertheless, a steady accumulation of field observations, insight gained from natural experiments, and novel taphonomic analyses have enhanced understanding of how primates interact with several predators, especially raptors, the subject of this review. Copyright © 2013 Wiley Periodicals, Inc.

  18. Systematic review

    DEFF Research Database (Denmark)

    Bager, Palle; Chauhan, Usha; Greveson, Kay

    2017-01-01

    of evidence is needed and the aim of this article was to systematically review the evidence of IBD advice lines. MATERIALS AND METHODS: A broad systematic literature search was performed to identify relevant studies addressing the effect of advice lines. The process of selection of the retrieved studies...... was undertaken in two phases. In phase one, all abstracts were review by two independent reviewers. In phase two, the full text of all included studies were independently reviewed by two reviewers. The included studies underwent quality assessment and data synthesis. RESULTS: Ten published studies and 10...... congress abstracts were included in the review. The studies were heterogeneous both in scientific quality and in the focus of the study. No rigorous evidence was found to support that advice lines improve disease activity in IBD and correspondingly no studies reported worsening in disease activity. Advice...

  19. Systematic Avocating

    Directory of Open Access Journals (Sweden)

    Jan Green

    2014-12-01

    Full Text Available Feeling obliged to undertake complex research tasks outside core working hours is a common occurrence in academia. Detailed and timely research projects are expected; the creation and defence of sufficient intervals within a crowded working schedule is one concern explored in this short version paper. Merely working longer hours fails to provide a satisfactory solution for individuals experiencing concerns of this nature. Personal effort and drive are utilised and requires the application of mental mustering and systematic procedures. The attitude to research work is treating the task as a hobby conceptualised as avocating. Whilst this provides a personal solution through immersion in the task, this approach should raise concerns for employers. The flexibility of grounded theory is evident and the freedom to draw on various bodies of knowledge provides fresh insight into a problem that occurs in organizations in many sectors experiencing multiple priorities. The application of the core category, systematic avocating, may prove beneficial.

  20. Cluster evolution

    International Nuclear Information System (INIS)

    Schaeffer, R.

    1987-01-01

    The galaxy and cluster luminosity functions are constructed from a model of the mass distribution based on hierarchical clustering at an epoch where the matter distribution is non-linear. These luminosity functions are seen to reproduce the present distribution of objects as can be inferred from the observations. They can be used to deduce the redshift dependence of the cluster distribution and to extrapolate the observations towards the past. The predicted evolution of the cluster distribution is quite strong, although somewhat less rapid than predicted by the linear theory

  1. CHEMICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Melvin

    1965-06-01

    How did life come to be on the surface of the earth? Darwin himself recognized that his basic idea of evolution by variation and natural selection must be a continuous process extending backward in time through that period in which the first living things arose and into the period of 'Chemical Evolution' which preceded it. We are approaching the examination of these events by two routes. One is to seek for evidence in the ancient rocks of the earth which were laid down prior to that time in which organisms capable of leaving their skeletons in the rocks to be fossilized were in existence. This period is sometime prior to approximately 600 million years ago. The earth is believed to have taken its present form approximately 4700 million years ago. We have found in rocks whose age is about 1000 million years certain organic molecules which are closely related to the green pigment of plants, chlorophyll. This seems to establish that green plants were already fluorishing prior to that time. We have now found in rocks of still greater age, namely, 2500 million years, the same kinds of molecules mentioned above which can be attributed to the presence of living organisms. If these molecules are as old as the rocks, we have thus shortened the time available for the generation of the complex biosynthetic sequences which give rise to these specific hydrocarbons (polyisoprenoids) to less than 2000 million years.

  2. Summing large-N towers in colour flow evolution

    International Nuclear Information System (INIS)

    Plaetzer, Simon

    2013-12-01

    We consider soft gluon evolution in the colour flow basis. We give explicit expressions for the colour structure of the (one-loop) soft anomalous dimension matrix for an arbitrary number of partons, and show how the successive exponentiation of classes of large-N contributions can be achieved to provide a systematic expansion of the evolution in terms of colour supressed contributions.

  3. Topological structure of the solution set for evolution inclusions

    CERN Document Server

    Zhou, Yong; Peng, Li

    2017-01-01

    This book systematically presents the topological structure of solution sets and attractability for nonlinear evolution inclusions, together with its relevant applications in control problems and partial differential equations. It provides readers the background material needed to delve deeper into the subject and explore the rich research literature.  In addition, the book addresses many of the basic techniques and results recently developed in connection with this theory, including the structure of solution sets for evolution inclusions with m-dissipative operators; quasi-autonomous and non-autonomous evolution inclusions and control systems;evolution inclusions with the Hille-Yosida operator; functional evolution inclusions; impulsive evolution inclusions; and stochastic evolution inclusions. Several applications of evolution inclusions and control systems are also discussed in detail.  Based on extensive research work conducted by the authors and other experts over the past four years, the information p...

  4. Om religion og evolution

    DEFF Research Database (Denmark)

    Geertz, Armin W.

    2011-01-01

    for kulturens kausale virkning på den menneskelige kognition og ikke mindst den hominine evolution. Ud fra, hvad vi ved om den menneskelige evolution, ses det, at den hominine evolution har en dybde, som sjældent medtænkes i teorier og hypoteser om den menneskelige evolution. Den menneskelige evolution er...

  5. Quasars and galactic evolution

    CERN Document Server

    Woltjer, L

    1978-01-01

    The evolution of quasars is discussed. It is noted that substantial clustering may be present at faint magnitudes. The relationship between quasar evolution and galactic evolution is considered. (4 refs).

  6. Preoperative diffusion tensor imaging-fiber tracking for facial nerve identification in vestibular schwannoma: a systematic review on its evolution and current status with a pooled data analysis of surgical concordance rates.

    Science.gov (United States)

    Savardekar, Amey R; Patra, Devi P; Thakur, Jai D; Narayan, Vinayak; Mohammed, Nasser; Bollam, Papireddy; Nanda, Anil

    2018-03-01

    OBJECTIVE Total tumor excision with the preservation of neurological function and quality of life is the goal of modern-day vestibular schwannoma (VS) surgery. Postoperative facial nerve (FN) paralysis is a devastating complication of VS surgery. Determining the course of the FN in relation to a VS preoperatively is invaluable to the neurosurgeon and is likely to enhance surgical safety with respect to FN function. Diffusion tensor imaging-fiber tracking (DTI-FT) technology is slowly gaining traction as a viable tool for preoperative FN visualization in patients with VS. METHODS A systematic review of the literature in the PubMed, Cochrane Library, and Web of Science databases was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and those studies that preoperatively localized the FN in relation to a VS using the DTI-FT technique and verified those preoperative FN tracking results by using microscopic observation and electrophysiological monitoring during microsurgery were included. A pooled analysis of studies was performed to calculate the surgical concordance rate (accuracy) of DTI-FT technology for FN localization. RESULTS Fourteen studies included 234 VS patients (male/female ratio 1:1.4, age range 17-75 years) who had undergone preoperative DTI-FT for FN identification. The mean tumor size among the studies ranged from 29 to 41.3 mm. Preoperative DTI-FT could not visualize the FN tract in 8 patients (3.4%) and its findings could not be verified in 3 patients (1.2%), were verified but discordant in 18 patients (7.6%), and were verified and concordant in 205 patients (87.1%). CONCLUSIONS Preoperative DTI-FT for FN identification is a useful adjunct in the surgical planning for large VSs (> 2.5 cm). A pooled analysis showed that DTI-FT successfully identifies the complete FN course in 96.6% of VSs (226 of 234 cases) and that FN identification by DTI-FT is accurate in 90.6% of cases (205 of 226

  7. Systematic Differences and Random Rates

    DEFF Research Database (Denmark)

    Knudsen, Thorbjørn; Levinthal, Daniel A.; Winter, Sidney G.

    2017-01-01

    evolutionary dynamics of firm entry, and the subsequent consolidation of market share and industry shake-out is considered, then during early epochs of industry evolution, one would tend to observe systematic differences in growth rates associated with firm’s competitive fitness. Thus, it is only......A fundamental premise of the strategy field is the existence of persistent firm level differences in resources and capabilities. This property of heterogeneity should express itself in a variety of empirical “signatures,” such as firm performance and arguably systematic and persistent differences...... component, but for much of an industry’s and firm’s history should have a random pattern consistent with the Gibrat property. The intuition is as follows. In a Cournot equilibrium, firms of better “type” (i.e., lower cost) realize a larger market share, but act with some restraint on their choice...

  8. Nudging Evolution?

    Directory of Open Access Journals (Sweden)

    Katharine N. Farrell

    2013-12-01

    Full Text Available This Special Feature, "Nudging Evolution? Critical Exploration of the Potential and Limitations of the Concept of Institutional Fit for the Study and Adaptive Management of Social-Ecological Systems," aims to contribute toward the development of social theory and social research methods for the study of social-ecological system dynamics. Our objective is to help strengthen the academic discourse concerning if, and if so, how, to what extent, and in what concrete ways the concept of institutional "fit" might play a role in helping to develop better understanding of the social components of interlinkages between the socioeconomic-cultural and ecological dynamics of social-ecological systems. Two clearly discernible patterns provide a map of this Special Feature: (1 One pattern is the authors' positions regarding the place and role of normativity within their studies and assessment of institutional fit. Some place this at the center of their studies, exploring phenomena endogenous to the process of defining what constitutes institutional fit, whereas others take the formation of norms as a phenomenon exogenous to their study. (2 Another pattern is the type of studies presented: critiques and elaborations of the theory, methods for judging qualities of fit, and/or applied case studies using the concept. As a body of work, these contributions highlight that self-understanding of social-ecological place, whether explicit or implicit, constitutes an important part of the study object, i.e., the role of institutions in social-ecological systems, and that this is, at the same time, a crucial point of reference for the scholar wishing to evaluate what constitutes institutional fit and how it might be brought into being.

  9. Evolution of the outflow activity of protostars

    International Nuclear Information System (INIS)

    Bontemps, Sylvain

    1996-01-01

    After a first part describing the formation of low-mass stars (sites of stellar formation, protostellar evolution) and matter outflows from young objects (molecular flows and their origin, optical and radio jets, outflow mechanisms), this research thesis discusses the evolution of molecular flows by reprinting a published article (Evolution of outflow activity around low-mass embedded young stellar objects), and by outlining some remaining issues (differences between clouds of stellar formation, morphological evolution of molecular flows). The author then discusses the continuous radio centimetre emission: origin, systematic search for Class 0 objects by using the VLA (Very Large Array radio interferometer), presentation of a new Class 0 protostar (HH24MMS). The author reports the study of H_2 emission in the infrared: generalities on protostellar shocks, infrared jet by HH24MMS, H_2 emission at 10 microns by using the ISOCAM camera [fr

  10. Better estimation of protein-DNA interaction parameters improve prediction of functional sites

    Directory of Open Access Journals (Sweden)

    O'Flanagan Ruadhan A

    2008-12-01

    Full Text Available Abstract Background Characterizing transcription factor binding motifs is a common bioinformatics task. For transcription factors with variable binding sites, we need to get many suboptimal binding sites in our training dataset to get accurate estimates of free energy penalties for deviating from the consensus DNA sequence. One procedure to do that involves a modified SELEX (Systematic Evolution of Ligands by Exponential Enrichment method designed to produce many such sequences. Results We analyzed low stringency SELEX data for E. coli Catabolic Activator Protein (CAP, and we show here that appropriate quantitative analysis improves our ability to predict in vitro affinity. To obtain large number of sequences required for this analysis we used a SELEX SAGE protocol developed by Roulet et al. The sequences obtained from here were subjected to bioinformatic analysis. The resulting bioinformatic model characterizes the sequence specificity of the protein more accurately than those sequence specificities predicted from previous analysis just by using a few known binding sites available in the literature. The consequences of this increase in accuracy for prediction of in vivo binding sites (and especially functional ones in the E. coli genome are also discussed. We measured the dissociation constants of several putative CAP binding sites by EMSA (Electrophoretic Mobility Shift Assay and compared the affinities to the bioinformatics scores provided by methods like the weight matrix method and QPMEME (Quadratic Programming Method of Energy Matrix Estimation trained on known binding sites as well as on the new sites from SELEX SAGE data. We also checked predicted genome sites for conservation in the related species S. typhimurium. We found that bioinformatics scores based on SELEX SAGE data does better in terms of prediction of physical binding energies as well as in detecting functional sites. Conclusion We think that training binding site detection

  11. Relic neutrino asymmetry evolution from first principles

    International Nuclear Information System (INIS)

    Bell, N.F.; Volkas, R.R.; Wong, Y.Y.Y.

    1998-09-01

    The exact Quantum Kinetic Equations for a two-flavour active-sterile neutrino system are used to provide a systematic derivation of approximate evolution equations for the relic neutrino asymmetry. An extension of the adiabatic approximation for matter-affected neutrino oscillations is developed which incorporates decoherence due to collisions. Exact and approximate expressions for the decoherence and repopulation functions are discussed. A first pass is made over the exact treatment of multi-flavour partially incoherent oscillations. (authors)

  12. Sociohistorical evolution of judo: introductory approaches

    Directory of Open Access Journals (Sweden)

    Orozimbo Cordeiro Júnior

    2008-06-01

    Full Text Available The sociohistorical evolution of judo provided by the research project Methodology for teaching judo from the critical–excelling stance is discussed in this article. The aim of the project was to establish a plan for systematizing judo as body culture constituent and scholastic knowledge of physical education. The ancillary pedagogical material is constituted by an introduction, objectives, contents, teaching methodology and evaluation system.

  13. Aptamer-based technology for food analysis.

    Science.gov (United States)

    Liu, Xiaofei; Zhang, Xuewu

    2015-01-01

    Aptamers are short and functional single-stranded oligonucleotide sequences selected from systematic evolution of ligands by exponential enrichment (SELEX) process, which have the capacity to recognize various classes of target molecules with high affinity and specificity. Various analytical aptamers acquired by SELEX are widely used in many research fields, such as medicine, biology, and chemistry. However, the application of this innovative and emerging technology to food safety is just in infant stage. Food safety plays a very important role in our daily lives because varieties of poisonous and harmful substances in food affect human health. Aptamer technique is promising, which can overcome many disadvantages of existing detection methods in food safety, such as long detection time, low sensitivity, difficult, and expensive antibody preparation. This review provides an overview of various aptamer screening technologies and summarizes the recent applications of aptamers in food safety, and future prospects are also discussed.

  14. Asymmetric PCR for good quality ssDNA generation towards DNA aptamer production

    Directory of Open Access Journals (Sweden)

    Junji Tominaga4

    2012-04-01

    Full Text Available Aptamers are ssDNA or RNA that binds to wide variety of target molecules with high affinity and specificity producedby systematic evolution of ligands by exponential enrichment (SELEX. Compared to RNA aptamer, DNA aptamer is muchmore stable, favourable to be used in many applications. The most critical step in DNA SELEX experiment is the conversion ofdsDNA to ssDNA. The purpose of this study was to develop an economic and efficient approach of generating ssDNA byusing asymmetric PCR. Our results showed that primer ratio (sense primer:antisense primer of 20:1 and sense primer amountof 10 to 100 pmol, up to 20 PCR cycles using 20 ng of initial template, in combination with polyacrylamide gel electrophoresis,were the optimal conditions for generating good quality and quantity of ssDNA. The generation of ssDNA via this approachcan greatly enhance the success rate of DNA aptamer generation.

  15. Cell-Specific Aptamers as Emerging Therapeutics

    Directory of Open Access Journals (Sweden)

    Cindy Meyer

    2011-01-01

    Full Text Available Aptamers are short nucleic acids that bind to defined targets with high affinity and specificity. The first aptamers have been selected about two decades ago by an in vitro process named SELEX (systematic evolution of ligands by exponential enrichment. Since then, numerous aptamers with specificities for a variety of targets from small molecules to proteins or even whole cells have been selected. Their applications range from biosensing and diagnostics to therapy and target-oriented drug delivery. More recently, selections using complex targets such as live cells have become feasible. This paper summarizes progress in cell-SELEX techniques and highlights recent developments, particularly in the field of medically relevant aptamers with a focus on therapeutic and drug-delivery applications.

  16. [Cell-ELA-based determination of binding affinity of DNA aptamer against U87-EGFRvIII cell].

    Science.gov (United States)

    Tan, Yan; Liang, Huiyu; Wu, Xidong; Gao, Yubo; Zhang, Xingmei

    2013-05-01

    A15, a DNA aptamer with binding specificity for U87 glioma cells stably overexpressing the epidermal growth factor receptor variant III (U87-EGFRvIII), was generated by cell systematic evolution of ligands by exponential enrichment (cell-SELEX) using a random nucleotide library. Subsequently, we established a cell enzyme-linked assay (cell-ELA) to detect the affinity of A15 compared to an EGFR antibody. We used A15 as a detection probe and cultured U87-EGFRvIII cells as targets. Our data indicate that the equilibrium dissociation constants (K(d)) for A15 were below 100 nmol/L and had similar affinity compared to an EGFR antibody for U87-EGFRvIII. We demonstrated that the cell-ELA was a useful method to determine the equilibrium dissociation constants (K(d)) of aptamers generated by cell-SELEX.

  17. Inlet Geomorphology Evolution

    Science.gov (United States)

    2015-04-01

    APR 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Inlet Geomorphology Evolution 5a. CONTRACT NUMBER 5b...Std Z39-18 Coastal Inlets Research Program Inlet Geomorphology Evolution The Inlet Geomorphology Evolution work unit of the CIRP evaluates

  18. Effort Flow Analysis: A Methodology for Directed Product Evolution Using Rigid Body and Compliant Mechanisms

    National Research Council Canada - National Science Library

    Greer, James

    2002-01-01

    This dissertation presents a systematic design methodology for directed product evolution that uses both rigid body and compliant mechanisms to facilitate component combination in the domain of mechanical products...

  19. Return of the mitochondrial DNA : Case study of mitochondrial genome evolution in the genus Fusarium

    NARCIS (Netherlands)

    Brankovics, Balázs

    2018-01-01

    Mitochondrial DNA played a prominent role in the fields of population genetics, systematics and evolutionary biology, due to its favorable characteristics, such as, uniparental inheritance, fast evolution and easy accessibility. However, the mitochondrial sequences have been mostly neglected in

  20. The systematization of practice

    DEFF Research Database (Denmark)

    Vidal, Rene Victor Valqui

    2002-01-01

    this paper presents an approach for the systematization of practical experiences whitin Operations Research, Community work, Systems Sciences, Action Research, etc. A case study is presented: the systematization of the activities of a development center in Denmark.......this paper presents an approach for the systematization of practical experiences whitin Operations Research, Community work, Systems Sciences, Action Research, etc. A case study is presented: the systematization of the activities of a development center in Denmark....

  1. Development of aptamers for use as radiopharmaceuticals in the bacterial infection identification; Desenvolvimento de aptameros especificos para aplicacao como radiofarmacos na identificacao de bacterias

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Ieda Mendes

    2013-08-01

    The difficulty in early detection of specific foci caused by bacteria in the bacterial infection has raised the need to search for new techniques for this purpose, since these foci require prolonged treatment with antibiotics and in some cases even drainage or, if applicable, removal of prostheses or grafts. Detection of bacterial infections by scintigraphy had the advantage that a whole body image could be obtained, since specific tracers were available. This study aims to obtain aptamers specific for bacteria identification for future use as radiopharmaceutical. The SELEX (Systematic Evolution of Ligands by Exponential Enrichment) methodology can generate oligonucleotides (aptamers) that are able to bind with high affinity and specificity to a specific target, from small molecules to complex proteins, by using rounds of enrichment and amplification. Aptamers can be labeled with different radionucleotides such as {sup 99}mTc, {sup 18}F and {sup 32}P. In this study, aptamers anti-peptidoglycan, the main component of the bacterial outer cell wall, were obtained through SELEX. Whole cells of Staphylococcus aureus were also used to perform the SELEX to cells (cell-SELEX). The selection of aptamers was performed by two different procedures (A and B). The A process has been accomplished by 15 SELEX rounds in which the separation of the oligonucleotides bound to the peptidoglycan of unbound ones was performed by filtration. In the B process 15 SELEX rounds were performed using the centrifugation for this separation, followed by 5 rounds cell-SELEX. The SELEX started with a pool of ssDNA (single stranded DNA). For A process, initially a library of ssDNA was incubated with peptidoglycan and the amplification of oligonucleotides that were able to bind to peptidoglycan was performed by PCR (Polymerase Chain Reation). The amplified oligonucleotides were again incubated with peptidoglycan, amplified and purified. At the end of 15 selection rounds the selected oligonucleotides

  2. Development of aptamers for use as radiopharmaceuticals in the bacterial infection identification

    International Nuclear Information System (INIS)

    Ferreira, Ieda Mendes

    2013-01-01

    The difficulty in early detection of specific foci caused by bacteria in the bacterial infection has raised the need to search for new techniques for this purpose, since these foci require prolonged treatment with antibiotics and in some cases even drainage or, if applicable, removal of prostheses or grafts. Detection of bacterial infections by scintigraphy had the advantage that a whole body image could be obtained, since specific tracers were available. This study aims to obtain aptamers specific for bacteria identification for future use as radiopharmaceutical. The SELEX (Systematic Evolution of Ligands by Exponential Enrichment) methodology can generate oligonucleotides (aptamers) that are able to bind with high affinity and specificity to a specific target, from small molecules to complex proteins, by using rounds of enrichment and amplification. Aptamers can be labeled with different radionucleotides such as 99 mTc, 18 F and 32 P. In this study, aptamers anti-peptidoglycan, the main component of the bacterial outer cell wall, were obtained through SELEX. Whole cells of Staphylococcus aureus were also used to perform the SELEX to cells (cell-SELEX). The selection of aptamers was performed by two different procedures (A and B). The A process has been accomplished by 15 SELEX rounds in which the separation of the oligonucleotides bound to the peptidoglycan of unbound ones was performed by filtration. In the B process 15 SELEX rounds were performed using the centrifugation for this separation, followed by 5 rounds cell-SELEX. The SELEX started with a pool of ssDNA (single stranded DNA). For A process, initially a library of ssDNA was incubated with peptidoglycan and the amplification of oligonucleotides that were able to bind to peptidoglycan was performed by PCR (Polymerase Chain Reation). The amplified oligonucleotides were again incubated with peptidoglycan, amplified and purified. At the end of 15 selection rounds the selected oligonucleotides were cloned

  3. Systematics and evolution in the West Indian iguanid genus Cyclura

    NARCIS (Netherlands)

    Schwartz, Albert; Carey, Michael

    1977-01-01

    Throughout the Greater Antilles, the Virgin Islands, the Cayman Islands, the Bahama Islands, and the Turks and Caicos islands occurs a group of moderate to very large lizards of the iguanid genus Cyclura. These ground iguanas form a conspicuous element of the herpetofaunas of their respective

  4. Life Cycle Evolution and Systematics of Campanulariid Hydrozoans

    Science.gov (United States)

    2004-09-01

    longissima - a true cosmopolite ? Cornelius (1975) synonymized Obelia longissima, as well as many other nominal Obelia species, into Obelia dichotoma. Based...biodiversity may be underestimated in the Campanulariidae and other hydrozoans, although some true cosmopolites may exist. This is in contrast to the most recent

  5. Natural kinds in evolution and systematics: metaphysical and epistemological considerations.

    Science.gov (United States)

    Brigandt, Ingo

    2009-06-01

    Despite the traditional focus on metaphysical issues in discussions of natural kinds in biology, epistemological considerations are at least as important. By revisiting the debate as to whether taxa are kinds or individuals, I argue that both accounts are metaphysically compatible, but that one or the other approach can be pragmatically preferable depending on the epistemic context. Recent objections against construing species as homeostatic property cluster kinds are also addressed. The second part of the paper broadens the perspective by considering homologues as another example of natural kinds, comparing them with analogues as functionally defined kinds. Given that there are various types of natural kinds, I discuss the different theoretical purposes served by diverse kind concepts, suggesting that there is no clear-cut distinction between natural kinds and other kinds, such as functional kinds. Rather than attempting to offer a unique metaphysical account of 'natural' kind, a more fruitful approach consists in the epistemological study of how different natural kind concepts are employed in scientific reasoning.

  6. The systematics and evolution of New World primates - A review.

    Science.gov (United States)

    Schneider, Horacio; Sampaio, Iracilda

    2015-01-01

    This paper provides an overview of the taxonomy of New World primates from proposals of the 1980's based on morphology to the great number of studies based on molecular data aiming for the elucidation of the phylogeny of New World monkeys. The innovations of the first molecular phylogeny presented by Schneider et al. (1993) positioned Callimico as a sister group of Callithrix and Cebuella; Callicebus as a member of the pitheciids; Brachyteles as sister to Lagothrix; and the night monkeys (Aotus), capuchins (Cebus) and squirrel monkeys (Saimiri) in the same clade with the small callitrichines. These results were subsequently confirmed by dozens of subsequent studies using data from DNA sequences. Some issues difficult to resolve with the phylogenetic analyses of DNA sequences, such as the diversification of the oldest lineages (pitheciids, atelids and cebids), and the confirmation of Aotus as a member of the Cebinae clade (together with Cebus/Saimiri), were clarified with new molecular approaches based on the presence or absence of Alu insertions as well as through the use of phylogenomics. At this time, all relationships at the intergeneric level had been deciphered, with the exception of the definition of the sister group of callitrichines (whether Aotus or Cebus/Saimiri are sister to callitrichines, or if Aotus, Saimiri and Cebus form a clade together). Future studies should prioritize the alpha taxonomy of most Neotropical primate groups, and the use of phylogenetic and geographic data, combined with reliable estimates of divergence times, to clarify the taxonomic status at species and genus level, as well as to help understand the evolutionary history of this remarkable and highly diversified group. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. The Transformation of Cyavana: A Case Study in Narrative Evolution

    Directory of Open Access Journals (Sweden)

    Emily West

    2017-03-01

    Full Text Available The assessment of possible genetic relationships between pairs of proposed narrative parallels currently relies on subjective conventional wisdom-based criteria. This essay presents an attempt at categorizing patterns of narrative evolution through the comparison of variants of orally-composed, fixed-text Sanskrit tales. Systematic examination of the changes that took place over the developmental arc of _The Tale of Cyavana_ offers a number of insights that may be applied to the understanding of the evolution of oral narratives in general. An evidence-based exposition of the principles that govern the process of narrative evolution could provide more accurate diagnostic tools for evaluating narrative parallels.

  8. Has Human Evolution Stopped?

    Directory of Open Access Journals (Sweden)

    Alan R. Templeton

    2010-07-01

    Full Text Available It has been argued that human evolution has stopped because humans now adapt to their environment via cultural evolution and not biological evolution. However, all organisms adapt to their environment, and humans are no exception. Culture defines much of the human environment, so cultural evolution has actually led to adaptive evolution in humans. Examples are given to illustrate the rapid pace of adaptive evolution in response to cultural innovations. These adaptive responses have important implications for infectious diseases, Mendelian genetic diseases, and systemic diseases in current human populations. Moreover, evolution proceeds by mechanisms other than natural selection. The recent growth in human population size has greatly increased the reservoir of mutational variants in the human gene pool, thereby enhancing the potential for human evolution. The increase in human population size coupled with our increased capacity to move across the globe has induced a rapid and ongoing evolutionary shift in how genetic variation is distributed within and among local human populations. In particular, genetic differences between human populations are rapidly diminishing and individual heterozygosity is increasing, with beneficial health effects. Finally, even when cultural evolution eliminates selection on a trait, the trait can still evolve due to natural selection on other traits. Our traits are not isolated, independent units, but rather are integrated into a functional whole, so selection on one trait can cause evolution to occur on another trait, sometimes with mildly maladaptive consequences.

  9. Multicolour Observations, Inhomogeneity & Evolution

    OpenAIRE

    Hellaby, Charles

    2000-01-01

    We propose a method of testing source evolution theories that is independent of the effects of inhomogeneity, and thus complementary to other studies of evolution. It is suitable for large scale sky surveys, and the new generation of large telescopes. In an earlier paper it was shown that basic cosmological observations - luminosity versus redshift, area distance versus redshift and number counts versus redshift - cannot separate the effects of cosmic inhomogeneity, cosmic evolution and sourc...

  10. Oxygen evolution reaction catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

    2016-09-06

    An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

  11. Stellar structure and evolution

    International Nuclear Information System (INIS)

    Kippernhahn, R.; Weigert, A.

    1990-01-01

    This book introduces the theory of the internal structure of stars and their evolution in time. It presents the basic physics of stellar interiors, methods for solving the underlying equations, and the most important results necessary for understanding the wide variety of stellar types and phenomena. The evolution of stars is discussed from their birth through normal evolution to possibly spectacular final stages. Chapters on stellar oscillations and rotation are included

  12. The Apache Point Observatory Galactic Evolution Experiment (APOGEE)

    DEFF Research Database (Denmark)

    Majewski, Steven R.; Schiavon, Ricardo P.; Frinchaboy, Peter M.

    2017-01-01

    The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the programs in the Sloan Digital Sky Survey III (SDSS-III), has now completed its systematic, homogeneous spectroscopic survey sampling all major populations of the Milky Way. After a three-year observing campaign on the...

  13. The (R)evolution of China: Offshore Wind Diffusion

    DEFF Research Database (Denmark)

    Poulsen, Thomas; Hasager, Charlotte Bay

    2017-01-01

    This research presents an industry level gap analysis for Chinese offshore wind, which serves as a way to illuminate how China may fast track industry evolution. The research findings provide insight into how the Chinese government strongly and systematically decrees state-owned Chinese firms to ...

  14. The Evolution and Prospects of Service-dominant Logic

    DEFF Research Database (Denmark)

    Wilden, Ralf; Akaka, Melissa Archpru; Karpen, Ingo O.

    2017-01-01

    potential for future development in this field have not been empirically examined. We explore the foundational research areas and evolution of SDL research through a systematic investigation, which combines cocitation analysis with a novel text mining tool, Leximancer. Specifically, we investigate...

  15. Systematic review automation technologies

    Science.gov (United States)

    2014-01-01

    Systematic reviews, a cornerstone of evidence-based medicine, are not produced quickly enough to support clinical practice. The cost of production, availability of the requisite expertise and timeliness are often quoted as major contributors for the delay. This detailed survey of the state of the art of information systems designed to support or automate individual tasks in the systematic review, and in particular systematic reviews of randomized controlled clinical trials, reveals trends that see the convergence of several parallel research projects. We surveyed literature describing informatics systems that support or automate the processes of systematic review or each of the tasks of the systematic review. Several projects focus on automating, simplifying and/or streamlining specific tasks of the systematic review. Some tasks are already fully automated while others are still largely manual. In this review, we describe each task and the effect that its automation would have on the entire systematic review process, summarize the existing information system support for each task, and highlight where further research is needed for realizing automation for the task. Integration of the systems that automate systematic review tasks may lead to a revised systematic review workflow. We envisage the optimized workflow will lead to system in which each systematic review is described as a computer program that automatically retrieves relevant trials, appraises them, extracts and synthesizes data, evaluates the risk of bias, performs meta-analysis calculations, and produces a report in real time. PMID:25005128

  16. Adaptability and evolution.

    Science.gov (United States)

    Bateson, Patrick

    2017-10-06

    The capacity of organisms to respond in their own lifetimes to new challenges in their environments probably appeared early in biological evolution. At present few studies have shown how such adaptability could influence the inherited characteristics of an organism's descendants. In part, this has been because organisms have been treated as passive in evolution. Nevertheless, their effects on biological evolution are likely to have been important and, when they occurred, accelerated the pace of evolution. Ways in which this might have happened have been suggested many times since the 1870s. I review these proposals and discuss their relevance to modern thought.

  17. Charting the evolution of approaches employed by the Global Alliance for Vaccines and Immunizations (GAVI) to address inequities in access to immunization: a systematic qualitative review of GAVI policies, strategies and resource allocation mechanisms through an equity lens (1999-2014).

    Science.gov (United States)

    Gandhi, Gian

    2015-11-30

    GAVI's focus on reducing inequities in access to vaccines, immunization, and GAVI funds, - both between and within countries - has changed over time. This paper charts that evolution. A systematic qualitative review was conducted by searching PubMed, Google Scholar and direct review of available GAVI Board papers, policies, and program guidelines. Documents were included if they described or evaluated GAVI policies, strategies, or programs and discussed equity of access to vaccines, utilization of immunization services, or GAVI funds in countries currently or previously eligible for GAVI support. Findings were grouped thematically, categorized into time periods covering GAVI's phases of operations, and assessed depending on whether the approaches mediated equity of opportunity or equity of outcomes between or within countries. Serches yielded 2816 documents for assessment. After pre-screening and removal of duplicates, 552 documents underwent detailed evaluation and pertinent information was extracted from 188 unique documents. As a global funding mechanism, GAVI responded rationally to a semi-fixed funding constraint by focusing on between-country equity in allocation of resources. GAVI's predominant focus and documented successes have been in addressing between-country inequities in access to vaccines comparing lower income (GAVI-eligible) countries with higher income (ineligible) countries. GAVI has had mixed results at addressing between-country inequities in utilization of immunization services, and has only more recently put greater emphasis and resources towards addressing within-country inequities in utilization to immunization services. Over time, GAVI has progressively added vaccines to its portfolio. This expansion should have addressed inter-country, inter-regional, inter-generational and gender inequities in disease burden, however, evidence is scant with respect to final outcomes. In its next phase of operations, the Alliance can continue to

  18. Evolution of Constructivism

    Science.gov (United States)

    Liu, Chu Chih; Chen, I Ju

    2010-01-01

    The contrast between social constructivism and cognitive constructivism are depicted in different ways in many studies. The purpose of this paper is to summarize the evolution of constructivism and put a focus on social constructivism from the perception of Vygotsky. This study provides a general idea of the evolution of constructivism for people…

  19. Evolution: Theory or Dogma?

    Science.gov (United States)

    Mayer, William V.

    In this paper the author examines the question of whether evolution is a theory or a dogma. He refutes the contention that there is a monolithic scientific conspiracy to present evolution as dogma and suggests that his own presentation might be more appropriately entitled "Creationism: Theory or Dogma." (PEB)

  20. Kognition, evolution og Bibel

    DEFF Research Database (Denmark)

    Jensen, Hans Jørgen Lundager

    2012-01-01

    En opfordring til, at Bibelvidneskaberne oprienterer sig i retning af aktuelle teorier om bio-kulturel evolution (Merlin Donald, aksetids-teori hos fx Robert Bellah)......En opfordring til, at Bibelvidneskaberne oprienterer sig i retning af aktuelle teorier om bio-kulturel evolution (Merlin Donald, aksetids-teori hos fx Robert Bellah)...

  1. Evolution for Young Victorians

    Science.gov (United States)

    Lightman, Bernard

    2012-01-01

    Evolution was a difficult topic to tackle when writing books for the young in the wake of the controversies over Darwin's "Origin of Species." Authors who wrote about evolution for the young experimented with different ways of making the complex concepts of evolutionary theory accessible and less controversial. Many authors depicted presented…

  2. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  3. Evolution, epigenetics and cooperation

    Indian Academy of Sciences (India)

    Explanations for biological evolution in terms of changes in gene frequencies refer to outcomes rather than process. Integrating epigenetic studies with older evolutionary theories has drawn attention to the ways in which evolution occurs. Adaptation at the level of the gene is givingway to adaptation at the level of the ...

  4. Evolution of complex dynamics

    Science.gov (United States)

    Wilds, Roy; Kauffman, Stuart A.; Glass, Leon

    2008-09-01

    We study the evolution of complex dynamics in a model of a genetic regulatory network. The fitness is associated with the topological entropy in a class of piecewise linear equations, and the mutations are associated with changes in the logical structure of the network. We compare hill climbing evolution, in which only mutations that increase the fitness are allowed, with neutral evolution, in which mutations that leave the fitness unchanged are allowed. The simple structure of the fitness landscape enables us to estimate analytically the rates of hill climbing and neutral evolution. In this model, allowing neutral mutations accelerates the rate of evolutionary advancement for low mutation frequencies. These results are applicable to evolution in natural and technological systems.

  5. Chemical evolution of galaxies

    CERN Document Server

    Matteucci, Francesca

    2012-01-01

    The term “chemical evolution of galaxies” refers to the evolution of abundances of chemical species in galaxies, which is due to nuclear processes occurring in stars and to gas flows into and out of galaxies. This book deals with the chemical evolution of galaxies of all morphological types (ellipticals, spirals and irregulars) and stresses the importance of the star formation histories in determining the properties of stellar populations in different galaxies. The topic is approached in a didactical and logical manner via galaxy evolution models which are compared with observational results obtained in the last two decades: The reader is given an introduction to the concept of chemical abundances and learns about the main stellar populations in our Galaxy as well as about the classification of galaxy types and their main observables. In the core of the book, the construction and solution of chemical evolution models are discussed in detail, followed by descriptions and interpretations of observations of ...

  6. Systematic text condensation

    DEFF Research Database (Denmark)

    Malterud, Kirsti

    2012-01-01

    To present background, principles, and procedures for a strategy for qualitative analysis called systematic text condensation and discuss this approach compared with related strategies.......To present background, principles, and procedures for a strategy for qualitative analysis called systematic text condensation and discuss this approach compared with related strategies....

  7. The Importance of Systematics

    Indian Academy of Sciences (India)

    1999-02-18

    Feb 18, 1999 ... Similarly, the work of Nathan Charles Rothschild, a taxonomic authority on flea species, was responsible for the discovery ... The use of genetic data for taxonomic purposes also brings systematics closer to realizing Darwin's desire that classification should reflect evolutionary relationships. Systematics is.

  8. Aptamers: Novel Molecules as Diagnostic Markers in Bacterial and Viral Infections?

    Directory of Open Access Journals (Sweden)

    Flávia M. Zimbres

    2013-01-01

    Full Text Available Worldwide the entire human population is at risk of infectious diseases of which a high degree is caused by pathogenic protozoans, worms, bacteria, and virus infections. Moreover the current medications against pathogenic agents are losing their efficacy due to increasing and even further spreading drug resistance. Therefore, there is an urgent need to discover novel diagnostic as well as therapeutic tools against infectious agents. In view of that, the Systematic Evolution of Ligands by Exponential Enrichment (SELEX represents a powerful technology to target selectively pathogenic factors as well as entire bacteria or viruses. SELEX uses a large combinatorial oligonucleic acid library (DNA or RNA which is processed a by high-flux in vitro screen of iterative cycles. The selected ligands, termed aptamers, are characterized by high specificity and affinity to their target molecule, which are already exploited in diagnostic and therapeutic applications. In this minireview we will discuss the current status of the SELEX technique applied on bacterial and viral pathogens.

  9. Aptamer-Based Technologies in Foodborne Pathogen Detection.

    Science.gov (United States)

    Teng, Jun; Yuan, Fang; Ye, Yingwang; Zheng, Lei; Yao, Li; Xue, Feng; Chen, Wei; Li, Baoguang

    2016-01-01

    Aptamers are single stranded DNA or RNA ligands, which can be selected by a method called systematic evolution of ligands by exponential enrichment (SELEX); and they can specifically recognize and bind to their targets. These unique characteristics of aptamers offer great potentials in applications such as pathogen detection and biomolecular screening. Pathogen detection is the critical means in detecting and identifying the problems related to public health and food safety; and only the rapid, sensitive and efficient detection technologies can enable the users to make the accurate assessments on the risks of infections (humans and animals) or contaminations (foods and other commodities) caused by various pathogens. This article reviews the development in the field of the aptamer-based approaches for pathogen detection, including whole-cell SELEX and Genomic SELEX. Nowadays, a variety of aptamer-based biosensors have been developed for pathogen detection. Thus, in this review, we also cover the development in aptamer-based biosensors including optical biosensors for multiple pathogen detection by multiple-labeling or label-free models such as fluorescence detection and surface plasmon resonance, electrochemical biosensors and lateral chromatography test strips, and their applications in pathogen detection and biomolecular screening. While notable progress has been made in the field in the last decade, challenges or drawbacks in their applications such as pathogen detection and biomolecular screening remain to be overcome.

  10. Aptamer-Based Technologies in Foodborne Pathogen Detection

    Directory of Open Access Journals (Sweden)

    Jun Teng

    2016-09-01

    Full Text Available Aptamers are single stranded DNA or RNA ligands, which can be selected by a method called systematic evolution of ligands by exponential enrichment (SELEX; and they can specifically recognize and bind to their targets. These unique characteristics of aptamers offer great potentials in applications such as pathogen detection and biomolecular screening. Pathogen detection is the first and critical means in detecting and identifying the problems related to public health and food safety; and only the rapid, sensitive and efficient detection technologies can enable the users to make to accurate assessments on the risk of infections (humans and animals or contaminations (foods and other commodities caused by various pathogens. This article reviews the developments in the field of the aptamer-based approaches for pathogen detection, including whole-cell SELEX and Genomic SELEX. Nowadays, a variety of aptamer-based biosensors have been developed for pathogen detection. Thus, in this review, we also cover the development of aptamer-based biosensors including optical biosensors for multiple pathogen detection in multiple-labeling or label-free models such as fluorescence detection and surface plasmon resonance, electrochemical biosensors, and lateral chromatography test strips, and their applications in the pathogen detection and biomolecular screening. While notable progress has been made in the field in the last decade, challenges or drawbacks in their applications such as pathogen detection and biomolecular screening, remain to be overcome.

  11. Selection of RNA Aptamers Against Botulinum Neurotoxin Type A Light Chain Through a Non-Radioactive Approach.

    Science.gov (United States)

    Chang, Tzuu-Wang; Janardhanan, Pavithra; Mello, Charlene M; Singh, Bal Ram; Cai, Shuowei

    2016-09-01

    Botulinum neurotoxin (BoNT), a category A agent, is the most toxic molecule known to mankind. The endopeptidase activity of light chain domain of BoNT is the cause for the inhibition of the neurotransmitter release and the flaccid paralysis that leads to lethality in botulism. Currently, antidotes are not available to reverse the flaccid paralysis caused by BoNT. In the present study, a non-radioactive-based systematic evolution of ligands by exponential enrichment (SELEX) process is developed by utilizing surface plasmon resonance to monitor the binding enrichment. Two RNA aptamers have been identified as strong binders against light chain of botulinum neurotoxin type A. These two aptamers showed strong inhibition activity on LCA, with IC50 in nanomolar range. Inhibition kinetic studies reveal mid nanomolar KI and non-competitive nature of their inhibition, suggesting that they have strong potential as antidotes that can reverse the symptom caused by BoNT/A. More importantly, we observed that the 2'-fluorine-pyrimidine-modified RNA aptamers identified here do not change their binding and biological activities. This observation could lead to a cost-effective way for SELEX, by using regular nucleotide during SELEX, and 2'-fluorine-pyrimidine-modified nucleotide for final application to enhance their RNase-resistance.

  12. Inhibition of BACE1 Activity by a DNA Aptamer in an Alzheimer's Disease Cell Model.

    Directory of Open Access Journals (Sweden)

    Huiyu Liang

    Full Text Available An initial step in amyloid-β (Aβ production includes amyloid precursor protein (APP cleavage via β-Site amyloid precursor protein cleaving enzyme 1 (BACE1. Increased levels of brain Aβ have been implicated in the pathogenesis of Alzheimer's disease (AD. Thus, β-secretase represents a primary target for inhibitor drug development in AD. In this study, aptamers were obtained from combinatorial oligonucleotide libraries using a technology referred to as systematic evolution of ligands by exponential enrichment (SELEX. A purified human BACE1 extracellular domain was used as a target to conduct an in vitro selection process using SELEX. Two DNA aptamers were capable of binding to BACE1 with high affinity and good specificity, with Kd values in the nanomolar range. We subsequently confirmed that one aptamer, A1, exhibited a distinct inhibitory effect on BACE1 activity in an AD cell model. We detected the effects of M17-APPsw cells that stably expressed Swedish mutant APP after aptamer A1 treatment. Aβ40 and Aβ42 concentrations secreted by M17-APPsw cells decreased intracellularly and in culture media. Furthermore, Western blot analysis indicated that sAPPβ expression significantly decreased in the A1 treated versus control groups. These findings support the preliminary feasibility of an aptamer evolved from a SELEX strategy to function as a potential BACE1 inhibitor. To our knowledge, this is the first study to acquire a DNA aptamer that exhibited binding specificity to BACE1 and inhibited its activity.

  13. Chromosomal Evolution in Chiroptera.

    Science.gov (United States)

    Sotero-Caio, Cibele G; Baker, Robert J; Volleth, Marianne

    2017-10-13

    Chiroptera is the second largest order among mammals, with over 1300 species in 21 extant families. The group is extremely diverse in several aspects of its natural history, including dietary strategies, ecology, behavior and morphology. Bat genomes show ample chromosome diversity (from 2n = 14 to 62). As with other mammalian orders, Chiroptera is characterized by clades with low, moderate and extreme chromosomal change. In this article, we will discuss trends of karyotypic evolution within distinct bat lineages (especially Phyllostomidae, Hipposideridae and Rhinolophidae), focusing on two perspectives: evolution of genome architecture, modes of chromosomal evolution, and the use of chromosome data to resolve taxonomic problems.

  14. Chromosomal Evolution in Chiroptera

    Directory of Open Access Journals (Sweden)

    Cibele G. Sotero-Caio

    2017-10-01

    Full Text Available Chiroptera is the second largest order among mammals, with over 1300 species in 21 extant families. The group is extremely diverse in several aspects of its natural history, including dietary strategies, ecology, behavior and morphology. Bat genomes show ample chromosome diversity (from 2n = 14 to 62. As with other mammalian orders, Chiroptera is characterized by clades with low, moderate and extreme chromosomal change. In this article, we will discuss trends of karyotypic evolution within distinct bat lineages (especially Phyllostomidae, Hipposideridae and Rhinolophidae, focusing on two perspectives: evolution of genome architecture, modes of chromosomal evolution, and the use of chromosome data to resolve taxonomic problems.

  15. Contemporary evolution strategies

    CERN Document Server

    Bäck, Thomas; Krause, Peter

    2013-01-01

    Evolution strategies have more than 50 years of history in the field of evolutionary computation. Since the early 1990s, many algorithmic variations of evolution strategies have been developed, characterized by the fact that they use the so-called derandomization concept for strategy parameter adaptation. Most importantly, the covariance matrix adaptation strategy (CMA-ES) and its successors are the key representatives of this group of contemporary evolution strategies. This book provides an overview of the key algorithm developments between 1990 and 2012, including brief descriptions of the a

  16. Weathering and landscape evolution

    Science.gov (United States)

    Turkington, Alice V.; Phillips, Jonathan D.; Campbell, Sean W.

    2005-04-01

    In recognition of the fundamental control exerted by weathering on landscape evolution and topographic development, the 35th Binghamton Geomorphology Symposium was convened under the theme of Weathering and Landscape Evolution. The papers and posters presented at the conference imparted the state-of-the-art in weathering geomorphology, tackled the issue of scale linkage in geomorphic studies and offered a vehicle for interdisciplinary communication on research into weathering and landscape evolution. The papers included in this special issue are encapsulated here under the general themes of weathering mantles, weathering and relative dating, weathering and denudation, weathering processes and controls and the 'big picture'.

  17. Dual phase evolution

    CERN Document Server

    Green, David G; Abbass, Hussein A

    2014-01-01

    This book explains how dual phase evolution operates in all these settings and provides a detailed treatment of the subject. The authors discuss the theoretical foundations for the theory, how it relates to other phase transition phenomena and its advantages in evolutionary computation and complex adaptive systems. The book provides methods and techniques to use this concept for problem solving. Dual phase evolution concerns systems that evolve via repeated phase shifts in the connectivity of their elements. It occurs in vast range of settings, including natural systems (species evolution, landscape ecology, geomorphology), socio-economic systems (social networks) and in artificial systems (annealing, evolutionary computing).

  18. Systematics of strength function sum rules

    Directory of Open Access Journals (Sweden)

    Calvin W. Johnson

    2015-11-01

    Full Text Available Sum rules provide useful insights into transition strength functions and are often expressed as expectation values of an operator. In this letter I demonstrate that non-energy-weighted transition sum rules have strong secular dependences on the energy of the initial state. Such non-trivial systematics have consequences: the simplification suggested by the generalized Brink–Axel hypothesis, for example, does not hold for most cases, though it weakly holds in at least some cases for electric dipole transitions. Furthermore, I show the systematics can be understood through spectral distribution theory, calculated via traces of operators and of products of operators. Seen through this lens, violation of the generalized Brink–Axel hypothesis is unsurprising: one expects sum rules to evolve with excitation energy. Furthermore, to lowest order the slope of the secular evolution can be traced to a component of the Hamiltonian being positive (repulsive or negative (attractive.

  19. Evolution of aging assessment methodologies

    International Nuclear Information System (INIS)

    McCrea, L.; Dam, R.; Gold, R.

    2011-01-01

    Under the influence of organizations like the IAEA and INPO the expectations of the regulator and plant operators alike are driving the evolution of aging assessment methodologies. The key result is that these assessments need to be executed more efficiently while supporting risk informed thinking within a living process. Some recent trends impacting aging assessments include new standards from the regulator requiring more frequent updates of aging assessments (RD-334), and broader component coverage driven by equipment reliability program demands (INPO AP-913). These trends point to the need to be able to do aging assessment more efficiently, and to manage the configuration. Some of the challenges include increasing efficiency while maintaining completeness and minimizing error, employing a systematic, well defined approach while maintaining the flexibility to apply the right level of effort to achieve desired results, and in particular, assuring that Aging Related Degradation Mechanisms (ARDMs) are sufficiently addressed. Meeting these needs creates a natural synergy with the Preventive Maintenance living program and therefore lends itself to a more integrated approach. To support this program, the SYSTMSTM software has been enhanced to accommodate for the various facets of an integrated program while meeting the needs described above. The systematic processes in SYSTMS are built with the vision of supporting risk-informed decision making as part of a larger risk-based functional tools suite. This paper intends to show how the utilities can benefit from the cost savings associated with increased assessment efficiency, and utilizing Candu Energy Inc.'s CANDU-specific knowledge-base and experience in aging assessment to get it right the first time. (author)

  20. Evolution of aging assessment methodologies

    Energy Technology Data Exchange (ETDEWEB)

    McCrea, L.; Dam, R.; Gold, R. [Candu Energy Inc., Mississauga, Ontario (Canada)

    2011-07-01

    Under the influence of organizations like the IAEA and INPO the expectations of the regulator and plant operators alike are driving the evolution of aging assessment methodologies. The key result is that these assessments need to be executed more efficiently while supporting risk informed thinking within a living process. Some recent trends impacting aging assessments include new standards from the regulator requiring more frequent updates of aging assessments (RD-334), and broader component coverage driven by equipment reliability program demands (INPO AP-913). These trends point to the need to be able to do aging assessment more efficiently, and to manage the configuration. Some of the challenges include increasing efficiency while maintaining completeness and minimizing error, employing a systematic, well defined approach while maintaining the flexibility to apply the right level of effort to achieve desired results, and in particular, assuring that Aging Related Degradation Mechanisms (ARDMs) are sufficiently addressed. Meeting these needs creates a natural synergy with the Preventive Maintenance living program and therefore lends itself to a more integrated approach. To support this program, the SYSTMSTM software has been enhanced to accommodate for the various facets of an integrated program while meeting the needs described above. The systematic processes in SYSTMS are built with the vision of supporting risk-informed decision making as part of a larger risk-based functional tools suite. This paper intends to show how the utilities can benefit from the cost savings associated with increased assessment efficiency, and utilizing Candu Energy Inc.'s CANDU-specific knowledge-base and experience in aging assessment to get it right the first time. (author)

  1. Generation of Transparent Oxygen Evolution Electrode Consisting of Regularly Ordered Nanoparticles from Self-Assembly Cobalt Phthalocyanine as a Template

    KAUST Repository

    Ziani, Ahmed; Shinagawa, Tatsuya; Stegenburga, Liga; Takanabe, Kazuhiro

    2016-01-01

    of the nanoparticles, and transparency of the catalysts. In this study, we present a systematic study of the structural and optical properties, surface morphologies, and electrochemical oxygen evolution reaction (OER) performance of cobalt oxide prepared from a

  2. Science, evolution, and creationism

    National Research Council Canada - National Science Library

    Committee on Revising Science and Creationism

    ... are more comfortable. In the book Science, Evolution, and Creationism, a group of experts assembled by the National Academy of Sciences and the Institute of Medicine explain the fundamental methods of science, document...

  3. Co-Evolution.

    Science.gov (United States)

    McGhee, Robert

    2002-01-01

    Discusses the role of techniques of DNA analysis in assessing the genetic relationships between various species. Focuses on wolf-dog evolution using DNA evidence and historical data about human/wolf-dog relationships. (DDR)

  4. Evolution of dosimetric phantoms

    International Nuclear Information System (INIS)

    Reddy, A.R.

    2010-01-01

    In this oration evolution of the dosimetric phantoms for radiation protection and for medical use is briefly reviewed. Some details of the development of Indian Reference Phantom for internal dose estimation are also presented

  5. Evolution of microbial pathogens

    National Research Council Canada - National Science Library

    DiRita, Victor J; Seifert, H. Steven

    2006-01-01

    ... A. Hogan vvi ■ CONTENTS 8. Evolution of Pathogens in Soil Rachel Muir and Man-Wah Tan / 131 9. Experimental Models of Symbiotic Host-Microbial Relationships: Understanding the Underpinnings of ...

  6. Evolution, epigenetics and cooperation.

    Science.gov (United States)

    Bateson, Patrick

    2014-04-01

    Explanations for biological evolution in terms of changes in gene frequencies refer to outcomes rather than process. Integrating epigenetic studies with older evolutionary theories has drawn attention to the ways in which evolution occurs. Adaptation at the level of the gene is givingway to adaptation at the level of the organism and higher-order assemblages of organisms. These ideas impact on the theories of how cooperation might have evolved. Two of the theories, i.e. that cooperating individuals are genetically related or that they cooperate for self-interested reasons, have been accepted for a long time. The idea that adaptation takes place at the level of groups is much more controversial. However, bringing together studies of development with those of evolution is taking away much of the heat in the debate about the evolution of group behaviour.

  7. Chemical evolution and life

    Directory of Open Access Journals (Sweden)

    Malaterre Christophe

    2015-01-01

    Full Text Available In research on the origins of life, the concept of “chemical evolution” aims at explaining the transition from non-living matter to living matter. There is however strong disagreement when it comes to defining this concept more precisely, and in particular with reference to a chemical form of Darwinian evolution: for some, chemical evolution is nothing but Darwinian evolution applied to chemical systems before life appeared; yet, for others, it is the type of evolution that happened before natural selection took place, the latter being the birthmark of living systems. In this contribution, I review the arguments defended by each side and show how both views presuppose a dichotomous definition of “life”.

  8. Evolution of interstellar grains

    International Nuclear Information System (INIS)

    Greenberg, J.M.

    1984-01-01

    The principal aim of this chapter is to derive the properties of interstellar grains as a probe of local physical conditions and as a basis for predicting such properties as related to infrared emissivity and radiative transfer which can affect the evolution of dense clouds. The first sections will develop the criteria for grain models based directly on observations of gas and dust. A summary of the chemical evolution of grains and gas in diffuse and dense clouds follows. (author)

  9. Evolution of Things

    OpenAIRE

    Eiben, A. E.; Ferreira, N.; Schut, M.; Kernbach, S.

    2011-01-01

    Evolution is one of the major omnipresent powers in the universe that has been studied for about two centuries. Recent scientific and technical developments make it possible to make the transition from passively understanding to actively mastering evolution. As of today, the only area where human experimenters can design and manipulate evolutionary processes in full is that of Evolutionary Computing, where evolutionary processes are carried out in a digital space, inside computers, in simulat...

  10. Manipulation of quantum evolution

    Science.gov (United States)

    Cabera, David Jose Fernandez; Mielnik, Bogdan

    1994-01-01

    The free evolution of a non-relativistic charged particle is manipulated using time-dependent magnetic fields. It is shown that the application of a programmed sequence of magnetic pulses can invert the free evolution process, forcing an arbitrary wave packet to 'go back in time' to recover its past shape. The possibility of more general operations upon the Schrodinger wave packet is discussed.

  11. Chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Matteucci, F.; Consiglio Nazionale delle Ricerche, Frascati

    1989-01-01

    In principle, a good model of galactic chemical evolution should fulfil the majority of well established observational constraints. The goal of this paper is to review the observational data together with the existing chemical evolution models for the Milky Way (the disk), Blue Compact and Elliptical galaxies and to show how well the models can account for the observations. Some open problems and future prospects are also discussed. (author)

  12. Developing theology for evolution

    Directory of Open Access Journals (Sweden)

    Chris Wiltsher

    2013-07-01

    Full Text Available This speculative paper explores one idea for approaching some of the problems which arise when the doctrines of Christian theology meet the current scientific understanding of evolution through natural selection. The main suggestion is that Christian theology should relax the requirement that God controls everything. Some implications of this move are explored, with a brief look at how similar ideas might be of use for non-Christian religions entering into dialogue with the theory of evolution

  13. Software evolution with XVCL

    DEFF Research Database (Denmark)

    Zhang, Weishan; Jarzabek, Stan; Zhang, Hongyu

    2004-01-01

    This chapter introduces software evolution with XVCL (XML-based Variant Configuration Language), which is an XML-based metaprogramming technique. As the software evolves, a large number of variants may arise, especially whtn such kinds of evolutions are related to multiple platforms as shown in our...... case study. Handling variants and tracing the impact of variants across the development lifecycle is a challenge. This chapter shows how we can maintain different versions of software in a reuse-based way....

  14. Evolution of massive stars

    International Nuclear Information System (INIS)

    Loore, C. de

    1984-01-01

    The evolution of stars with masses larger than 15 sun masses is reviewed. These stars have large convective cores and lose a substantial fraction of their matter by stellar wind. The treatment of convection and the parameterisation of the stellar wind mass loss are analysed within the context of existing disagreements between theory and observation. The evolution of massive close binaries and the origin of Wolf-Rayet Stars and X-ray binaries is also sketched. (author)

  15. Divergent Cumulative Cultural Evolution

    OpenAIRE

    Marriott, Chris; Chebib, Jobran

    2016-01-01

    Divergent cumulative cultural evolution occurs when the cultural evolutionary trajectory diverges from the biological evolutionary trajectory. We consider the conditions under which divergent cumulative cultural evolution can occur. We hypothesize that two conditions are necessary. First that genetic and cultural information are stored separately in the agent. Second cultural information must be transferred horizontally between agents of different generations. We implement a model with these ...

  16. Selection and application of ssDNA aptamers to detect active TB from sputum samples

    CSIR Research Space (South Africa)

    Rotherham, LS

    2012-10-01

    Full Text Available and specificity, has been made possible by the development of the systematic evolution of ligands by exponential enrichment (SELEX) process [22,23,24]. Since aptamers can be produced using chemical synthesis or by PCR, the cost of producing aptamers is 10... urea, 25 mM Tris-HCl, 200 mM NaCl, 10 mM imidazole, pH 7.4). The cells were disrupted by sonication (Bandelin Sonoplus HD2070), after which the lysate was clarified by centrifugation (14,000 rpm for 15 min at 4uC). For CFP-10, the supernatant...

  17. The Importance of Systematics

    Indian Academy of Sciences (India)

    1999-02-18

    Feb 18, 1999 ... applied bioiogy. When natural ... more than the science of classification, and encompasses studies on ecology, evolution and biodiversity. Thus, some ... agrees. For example, let us assume that there is a genus called A.

  18. Evolution: from cosmogenesis to biogenesis

    International Nuclear Information System (INIS)

    Lukacs, B.; Berczi, Sz.; Molnar, I.; Paal, G.

    1990-11-01

    The volume contains the material of an interdisciplinary evolution symposium. The purpose was to shed some light on possible connections between steps of evolution of matter on different levels of organisation. The topics involved are as follow: cosmogenesis; galactic and stellar evolution; formation and evolution of the solar system; global atmospheric and tectonic changes of Earth; viral evolution; phylogeny and evolution of terrestrial life; evolution of neural system; hominization. The material also includes some discussions of the underlying phenomena and laws of nature. (author)

  19. The (R)evolution of China: Offshore Wind Diffusion

    DEFF Research Database (Denmark)

    Poulsen, Thomas; Hasager, Charlotte Bay

    2017-01-01

    This research presents an industry level gap analysis for Chinese offshore wind, which serves as a way to illuminate how China may fast track industry evolution. The research findings provide insight into how the Chinese government strongly and systematically decrees state-owned Chinese firms...... successfully forge long-term alliances also for future Chinese wind energy export projects. Examples of past efforts of collaboration not yielding desired results have been included as well. At policy level, recommendations are provided on how the evolution of the Chinese offshore wind power industry can...... be fast-tracked to mirror the revolutionary pace, volume, and velocity which the Chinese onshore wind power industry has mustered....

  20. Lossless Conditional Schema Evolution

    DEFF Research Database (Denmark)

    Jensen, Ole Guttorm; Bøhlen, Michael Hanspeter

    2003-01-01

    The paper considers conditional schema evolution, where schema changes change the schema of the tuples that satisfy the change condition. When the schema of a relation change some tuples may no longer fit the current schema. Handling the mismatch between the intended schema of tuples and the reco......The paper considers conditional schema evolution, where schema changes change the schema of the tuples that satisfy the change condition. When the schema of a relation change some tuples may no longer fit the current schema. Handling the mismatch between the intended schema of tuples...... and the recorded schema of tuples is at the core of a DBMS that supports schema evolution. We propose to keep track of schema mismatches at the level of individual tuples, and prove that conditionally evolving schemas, in contrast to current commercial database systems, are lossless when the schema evolves...

  1. Evolution of Scale Worms

    DEFF Research Database (Denmark)

    Gonzalez, Brett Christopher

    ) caves, and the interstitium, recovering six monophyletic clades within Aphroditiformia: Acoetidae, Aphroditidae, Eulepethidae, Iphionidae, Polynoidae, and Sigalionidae (inclusive of the former ‘Pisionidae’ and ‘Pholoidae’), respectively. Tracing of morphological character evolution showed a high degree...... of adaptability and convergent evolution between relatively closely related scale worms. While some morphological and behavioral modifications in cave polynoids reflected troglomorphism, other modifications like eye loss were found to stem from a common ancestor inhabiting the deep sea, further corroborating...... the deep sea ancestry of scale worm cave fauna. In conclusion, while morphological characterization across Aphroditiformia appears deceptively easy due to the presence of elytra, convergent evolution during multiple early radiations across wide ranging habitats have confounded our ability to reconstruct...

  2. Education and Evolution

    DEFF Research Database (Denmark)

    Hjermitslev, Hans Henrik

    2015-01-01

    Herbert Spencer’s ideas were first introduced to a Scandinavian audience in the early 1870s when the Danish philosopher Harald Høffding published and lectured on his evolutionary philosophy. At this time, Høffding also played an important role in disseminating Charles Darwin’s theory of evolution...... and in discussing the philosophical consequences of an evolutionary worldview. In the late 1870s and 1880s several of Spencer’s works were translated into Danish and Swedish and he became a household name among liberal intellectuals who primarily discussed his views on education and evolution. His most influential...... known foreign thinkers in the general public at the time of his death in 1903. Moreover, in the decades around 1900 Spencer’s thoughts on education were part of the curricula at many colleges of education. Spencer’s ideas on evolution and education were thus widely circulated and positively received...

  3. Quantum evolution across singularities

    International Nuclear Information System (INIS)

    Craps, Ben; Evnin, Oleg

    2008-01-01

    Attempts to consider evolution across space-time singularities often lead to quantum systems with time-dependent Hamiltonians developing an isolated singularity as a function of time. Examples include matrix theory in certain singular time-dependent backgounds and free quantum fields on the two-dimensional compactified Milne universe. Due to the presence of the singularities in the time dependence, the conventional quantum-mechanical evolution is not well-defined for such systems. We propose a natural way, mathematically analogous to renormalization in conventional quantum field theory, to construct unitary quantum evolution across the singularity. We carry out this procedure explicitly for free fields on the compactified Milne universe and compare our results with the matching conditions considered in earlier work (which were based on the covering Minkowski space)

  4. Boussinesq evolution equations

    DEFF Research Database (Denmark)

    Bredmose, Henrik; Schaffer, H.; Madsen, Per A.

    2004-01-01

    This paper deals with the possibility of using methods and ideas from time domain Boussinesq formulations in the corresponding frequency domain formulations. We term such frequency domain models "evolution equations". First, we demonstrate that the numerical efficiency of the deterministic...... Boussinesq evolution equations of Madsen and Sorensen [Madsen, P.A., Sorensen, O.R., 1993. Bound waves and triad interactions in shallow water. Ocean Eng. 20 359-388] can be improved by using Fast Fourier Transforms to evaluate the nonlinear terms. For a practical example of irregular waves propagating over...... a submerged bar, it is demonstrated that evolution equations utilising FFT can be solved around 100 times faster than the corresponding time domain model. Use of FFT provides an efficient bridge between the frequency domain and the time domain. We utilise this by adapting the surface roller model for wave...

  5. Software architecture evolution

    DEFF Research Database (Denmark)

    Barais, Olivier; Le Meur, Anne-Francoise; Duchien, Laurence

    2008-01-01

    Software architectures must frequently evolve to cope with changing requirements, and this evolution often implies integrating new concerns. Unfortunately, when the new concerns are crosscutting, existing architecture description languages provide little or no support for this kind of evolution....... The software architect must modify multiple elements of the architecture manually, which risks introducing inconsistencies. This chapter provides an overview, comparison and detailed treatment of the various state-of-the-art approaches to describing and evolving software architectures. Furthermore, we discuss...... one particular framework named Tran SAT, which addresses the above problems of software architecture evolution. Tran SAT provides a new element in the software architecture descriptions language, called an architectural aspect, for describing new concerns and their integration into an existing...

  6. Validering av Evolution 220

    OpenAIRE

    Krakeli, Tor-Arne

    2013-01-01

    - Det har blitt kjøpt inn et nytt spektrofotometer (Evolution 220, Thermo Scientific) til BioLab Nofima. I den forbindelsen har det blitt utført en validering som involverer kalibreringsstandarder fra produsenten og en test på normal distribusjon (t-test) på to metoder (Total fosfor, Tryptofan). Denne valideringen fant Evolution 220 til å være et akseptabelt alternativ til det allerede benyttede spektrofotometeret (Helios Beta). På bakgrunn av noen instrumentbegrensninger må de aktuelle an...

  7. TMDs: Evolution, modeling, precision

    Directory of Open Access Journals (Sweden)

    D’Alesio Umberto

    2015-01-01

    Full Text Available The factorization theorem for qT spectra in Drell-Yan processes, boson production and semi-inclusive deep inelastic scattering allows for the determination of the non-perturbative parts of transverse momentum dependent parton distribution functions. Here we discuss the fit of Drell-Yan and Z-production data using the transverse momentum dependent formalism and the resummation of the evolution kernel. We find a good theoretical stability of the results and a final χ2/points ≲ 1. We show how the fixing of the non-perturbative pieces of the evolution can be used to make predictions at present and future colliders.

  8. Emergence and Evolution

    DEFF Research Database (Denmark)

    Bullwinkle, Tammy J; Ibba, Michael

    2013-01-01

    ancestor and as such they provide insights into the evolution and development of the extant genetic code. Although the aaRSs have long been viewed as a highly conserved group of enzymes, findings within the last couple of decades have started to demonstrate how diverse and versatile these enzymes really...... are. Beyond their central role in translation, aaRSs and their numerous homologs have evolved a wide array of alternative functions both inside and outside translation. Current understanding of the emergence of the aaRSs, and their subsequent evolution into a functionally diverse enzyme family...

  9. Evolution 2.0

    DEFF Research Database (Denmark)

    Andersen, Casper; Bek-Thomsen, Jakob; Clasen, Mathias

    2013-01-01

    Studies in the history of science and education have documented that the reception and understanding of evolutionary theory is highly contingent on local factors such as school systems, cultural traditions, religious beliefs, and language. This has important implications for teaching evolution...... audiences readily available. As more and more schools require teachers to use low cost or free web-based materials, in the research community we need to take seriously how to facilitate that demand in communication strategies on evolution. This article addresses this challenge by presenting the learning...

  10. Methylome evolution in plants.

    Science.gov (United States)

    Vidalis, Amaryllis; Živković, Daniel; Wardenaar, René; Roquis, David; Tellier, Aurélien; Johannes, Frank

    2016-12-20

    Despite major progress in dissecting the molecular pathways that control DNA methylation patterns in plants, little is known about the mechanisms that shape plant methylomes over evolutionary time. Drawing on recent intra- and interspecific epigenomic studies, we show that methylome evolution over long timescales is largely a byproduct of genomic changes. By contrast, methylome evolution over short timescales appears to be driven mainly by spontaneous epimutational events. We argue that novel methods based on analyses of the methylation site frequency spectrum (mSFS) of natural populations can provide deeper insights into the evolutionary forces that act at each timescale.

  11. Chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Vigroux, Laurent

    1979-01-01

    This research thesis addresses theories on the chemical evolution of galaxies which aim at explaining abundances of different elements in galaxies, and more particularly aims at improving the model by modifying hypotheses. After a description of the simple model and of its uncertainties, the author shows how it is possible to understand the evolution of the main elements. Predictions obtained with this model are then compared with the present knowledge on galaxies by considering them according to an increasing complexity: Sun's neighbourhood, our galaxy, other spiral galaxies, elliptical galaxies, and finally galaxy clusters. A specific attention is given to irregular galaxies which are the simplest systems [fr

  12. Outburst flood evolution at Russell Glacier, western Greenland

    DEFF Research Database (Denmark)

    Carrivick, Jonathan L.; Turner, Andy G.D.; Russell, Andrew J.

    2013-01-01

    Glacial lake outburst floods have produced a distinctive and widespread Quaternary record both onshore and offshore via widespread and intense geomorphological impacts, yet these impacts remain poorly understood due to a lack of modern analogues. This study therefore makes a systematic quantifica...... of including intermediary lakes. Modern hazard mitigation studies could usefully note the potential use of reservoirs as an outburst flood alleviation resource.......Glacial lake outburst floods have produced a distinctive and widespread Quaternary record both onshore and offshore via widespread and intense geomorphological impacts, yet these impacts remain poorly understood due to a lack of modern analogues. This study therefore makes a systematic...... quantification of the evolution of a bedrock-channelled outburst flood. Channel topography was obtained from digitised aerial photographs, a 5 m grid resolution DEM and bathymetric surveys. Flood inundation was measured in the field from dGPS measurements. Flood evolution was analysed with application...

  13. GENUSA Fuel Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Choithramani, Sylvia; Malpica, Maria [ENUSA Industrias Avanzadas, GENUSA, Josefa Valcarcel, 26 28027 Madrid (Spain); Fawcett, Russel [Global Nuclear Fuel (United States)

    2009-06-15

    deliver improved performance. Relative to the 8x8 fuel operated in the 1980's, today's designs provide {approx}25% more efficiency and power capability and twice as much energy. Because of GENUSA's evolutionary design commitment, these product improvements have been successfully rolled out to our customers with no design or fabrication-related performance surprises. Additionally, this has been accomplished with an accompanying steady improvement in fuel reliability. In the past three decades, fuel reliability has improved by approximately three orders of magnitude. That is, the fuel rod leaker rate has been reduced from over five hundred rods per million operating, to less than ten. In past decades, most plants experienced failures each cycle, and fleet-wide failure mechanisms drove reliability statistics. Today, a small minority of our customers' plants experience failures in any cycle, mainly recurrent, low level debris fretting failures in a handful of plants. GENUSA is committed to providing the most robust, and balanced, fuel solutions to our customers based on our extensive experience and technological capabilities. Identifying and successfully mitigating the mechanisms that cause fuel failures has been instrumental in this observed improvement in fuel reliability. GENUSA systematically identified and eliminated mechanisms leading to failure through pool-side and hot cell examinations, and feedback of lessons learned into the design and fabrication of the fuel. Some of the highly successful mitigating actions during this history include: - Improved pellet fabrication in the 1970's to eliminate cladding primary hydride failures; - Corrosion-resistant cladding, with a chemistry and microstructure specifically targeted to protect against crud-induced corrosion (CILC) failures; - Improved cladding and welding fabrication and inspection techniques that assured the hermeticity and quality of the delivered fuel rod; - Tightened pellet missing

  14. Evolution of housing

    NARCIS (Netherlands)

    Slob, C.; Mohammadi, S.; Geraedts, R.P.

    2012-01-01

    ‘Perfection means something is complete and stands still and what stands still doesn’t change or evolve and is automatically dead. Everything in the universe changes, evolution implies that the creation is not complete hence the possibility of evolving’ (Osho, 1985). Our society and economy are

  15. The Evolution of Empathy

    Science.gov (United States)

    Hackney, Harold

    1978-01-01

    Therapeutic empathy has been an often-used construct by counseling professionals. Through that usage, the term has evolved in meaning and significance from its original presentation by Carl Rogers. This article traces that evolution by identifying its users and contributors over the past 20 years. (Author)

  16. Evolution Perception with Metaphors

    Science.gov (United States)

    Yilmaz, Fatih

    2016-01-01

    The main objective of this research is to find out how the teacher candidates who graduated from the Faculty of Theology and study in pedagogical formation program perceive the theory of evolution. Having a descriptive characteristic, this research is conducted with 63 Faculty of Theology graduate teacher candidates of which 36 is women and 27 is…

  17. Evolution of Business Models

    DEFF Research Database (Denmark)

    Antero, Michelle C.; Hedman, Jonas; Henningsson, Stefan

    2013-01-01

    The ERP industry has undergone dramatic changes over the past decades due to changing market demands, thereby creating new challenges and opportunities, which have to be managed by ERP vendors. This paper inquires into the necessary evolution of business models in a technology-intensive industry (e...

  18. Evolution of subsidiary competences

    DEFF Research Database (Denmark)

    Geisler Asmussen, Christian; Pedersen, Torben; Dhanaraj, Charles

    of competitive advantage of nations, we hypothesize the contingencies under which heterogeneity in host environments influences subsidiary competence configuration. We test our model with data from more than 2,000 subsidiaries in seven Western European countries. Our results provide new insights on the evolution...

  19. Titan Polar Landscape Evolution

    Science.gov (United States)

    Moore, Jeffrey M.

    2016-01-01

    With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

  20. Kinship and Human Evolution

    DEFF Research Database (Denmark)

    Bergendorff, Steen

    This book offers a exiting new explanation of human evolution. Based on insight from Anthropology is shows that human became 'cultured' beings capable of symbolic thought by developing rasting kinship based between groups that could not other wise survive in the harah climate condition during...

  1. Software Architecture Evolution

    Science.gov (United States)

    Barnes, Jeffrey M.

    2013-01-01

    Many software systems eventually undergo changes to their basic architectural structure. Such changes may be prompted by new feature requests, new quality attribute requirements, changing technology, or other reasons. Whatever the causes, architecture evolution is commonplace in real-world software projects. Today's software architects, however,…

  2. Open-Ended Evolution

    DEFF Research Database (Denmark)

    Taylor, Tim; Bedau, Mark A.; Channon, Alastair

    2016-01-01

    This report describes the First Workshop on Open-Ended Evolution: Recent Progress and Future Milestones (OEE1), held during the ECAL 2015 conference at the University of York, U.K., in July 2015. We briefly summarise the content of the talks and discussions and the workshop, and provide links...

  3. The Evolution of Galaxies

    Czech Academy of Sciences Publication Activity Database

    Palouš, Jan

    2007-01-01

    Roč. 17, - (2007), s. 34-40 ISSN 1220-5168. [Heliospere and galaxy. Sinaia, 03.05.2007-05.05.2007] R&D Projects: GA MŠk(CZ) LC06014 Institutional research plan: CEZ:AV0Z10030501 Keywords : ISM structure * stars formation * evolution of galaxies Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  4. MDSplus evolution continues

    International Nuclear Information System (INIS)

    Manduchi, G.; Fredian, T.W.; Stillerman, J.A.

    2012-01-01

    Highlights: ► The paper describes the recent evolution of the MDSplus data system. ► It presents a Use Case to explain MDSplus expressions. ► It presents the features recently developed. ► It presents the features under development. - Abstract: The MDSplus data system has been in operation on several fusion machines since 1991 and it is currently in use at over 30 sites spread over 5 continents. A consequence is the extensive feedback provided by the MDSplus user community for bug fixes and improvements and therefore the evolution of MDSplus is keeping pace with the evolution in data acquisition and management techniques. In particular, the recent evolution of MDSplus has been driven by the change in the paradigm for data acquisition in long lasting plasma discharges, where a sustained data stream is transferred from the acquisition devices into the database. Several new features are currently available or are being implemented in MDSplus. The features already implemented include a comprehensive Object-Oriented interface to the system, the python support for data acquisition devices and the full integration in EPICS. Work is in progress for the integration of multiple protocols and security systems in remote data access, a new high level data view layer and a new version of the jScope tool for online visualization and the optimized visualization of very large signals.

  5. Common envelope evolution

    NARCIS (Netherlands)

    Taam, Ronald E.; Ricker, Paul M.

    2010-01-01

    The common envelope phase of binary star evolution plays a central role in many evolutionary pathways leading to the formation of compact objects in short period systems. Using three dimensional hydrodynamical computations, we review the major features of this evolutionary phase, focusing on the

  6. Methylome evolution in plants

    NARCIS (Netherlands)

    Vidalis, Amaryllis; Živković, Daniel; Wardenaar, René; Roquis, David; Tellier, Aurélien; Johannes, Frank

    2016-01-01

    Despite major progress in dissecting the molecular pathways that control DNA methylation patterns in plants, little is known about the mechanisms that shape plant methylomes over evolutionary time. Drawing on recent intra- and interspecific epigenomic studies, we show that methylome evolution over

  7. The Evolution of Darwinism.

    Science.gov (United States)

    Stebbins, G. Ledyard; Ayala, Francisco J.

    1985-01-01

    Recent developments in molecular biology and new interpretations of the fossil record are gradually altering and adding to Charles Darwin's theory, which has been the standard view of the process of evolution for 40 years. Several of these developments and interpretations are identified and discussed. (JN)

  8. Darwinism: Evolution or Revolution?

    Science.gov (United States)

    Holt, Niles R.

    1989-01-01

    Maintains that Darwin's theory of evolution was more than a science versus religion debate; rather it was a revolutionary concept that influenced numerous social and political ideologies and movements throughout western history. Traces the impact of Darwin's work historically, utilizing a holistic approach. (RW)

  9. Modeling shoreface profile evolution

    NARCIS (Netherlands)

    Stive, M.J.F.; De Vriend, H.J.

    1995-01-01

    Current knowledge of hydro-, sediment and morpho-dynamics in the shoreface environment is insufficient to undertake shoreface-profile evolution modelling on the basis of first physical principles. We propose a simple, panel-type model to map observed behaviour. The internal dynamics are determined

  10. Modelling shoreface profile evolution

    NARCIS (Netherlands)

    Stive, Marcel J.F.; de Vriend, Huib J.

    1995-01-01

    Current knowledge of hydro-, sediment and morpho-dynamics in the shoreface environment is insufficient to undertake shoreface-profile evolution modelling on the basis of first physical principles. We propose a simple, panel-type model to map observed behaviour. The internal dynamics are determined

  11. The Idea of Evolution

    Science.gov (United States)

    Mathison, Jane

    1976-01-01

    The idea of evolution is examined in a historical perspective in this article. Considerable discussion is given to the works of Lamarck and Darwin. The evolutionary process is also examined with respect to philosophy, art and music history, and man's place in nature. References are included. (MA)

  12. Evolution and Education

    Science.gov (United States)

    Washburn, S. L.

    1974-01-01

    Education should give an understanding of the world and of man, as well as offer the vocational training, at which the university excells. The use of case studies to provide immediate insight into advancing knowledge and the study of evolution have important instructional and educational implication for the goal of understanding man. (JH)

  13. Evolution, Insight and Truth?

    Science.gov (United States)

    Newall, Emma

    2017-01-01

    Evolution has been positioned at the centre of conflict between scientific and religious explanations of the workings of the world. However, little research has examined other possible reasons for some people rejecting scientific explanations. The author's research indicates that for some people, irrespective of faith, the ideas associated with…

  14. Evolution. Teacher's Guide.

    Science.gov (United States)

    Bershad, Carol

    This teacher's guide was developed to assist teachers in the use of multimedia resources for the Public Broadcasting System (PBS) program, "Evolution." Each unit uses an inquiry-based approach to meet the National Science Education Standards. Units include: (1) "What is the Nature of Science?"; (2) "Who Was Charles Darwin?"; (3) "What is the…

  15. Relations between the galactic evolution and the stellar evolution

    International Nuclear Information System (INIS)

    Audouze, J.

    1984-01-01

    After a quick definition of the galactic evolution and a summary of the basic ingredients (namely the abundances of the chemical elements observed in different astrophysical sites), the parameters directly related to the stellar evolution which govern the galactic evolution are outlined. They are the rates of star formation, the initial mass functions and the various nucleosynthetic yields. The 'classical' models of chemical evolution of galaxies are then briefly recalled. Finally, attention is drawn to three recent contributions concerning both the galactic evolution and the stellar evolution. They are (i) some prediction of the rate of star formation for low mass stars made from the planetary nebula abundance distribution (ii) the chemical evolution of C, O and Fe and (iii) the chemical evolution of the galactic interstellar medium. (Auth.)

  16. Soft gluon evolution and non-global logarithms

    Science.gov (United States)

    Martínez, René Ángeles; De Angelis, Matthew; Forshaw, Jeffrey R.; Plätzer, Simon; Seymour, Michael H.

    2018-05-01

    We consider soft-gluon evolution at the amplitude level. Our evolution algorithm applies to generic hard-scattering processes involving any number of coloured partons and we present a reformulation of the algorithm in such a way as to make the cancellation of infrared divergences explicit. We also emphasise the special role played by a Lorentz-invariant evolution variable, which coincides with the transverse momentum of the latest emission in a suitably defined dipole zero-momentum frame. Handling large colour matrices presents the most significant challenge to numerical implementations and we present a means to expand systematically about the leading colour approximation. Specifically, we present a systematic procedure to calculate the resulting colour traces, which is based on the colour flow basis. Identifying the leading contribution leads us to re-derive the Banfi-Marchesini-Smye equation. However, our formalism is more general and can systematically perform resummation of contributions enhanced by the t'Hooft coupling α s N ˜ 1, along with successive perturbations that are parametrically suppressed by powers of 1 /N . We also discuss how our approach relates to earlier work.

  17. Urban Evolution: The Role of Water

    Directory of Open Access Journals (Sweden)

    Sujay S. Kaushal

    2015-07-01

    Full Text Available The structure, function, and services of urban ecosystems evolve over time scales from seconds to centuries as Earth’s population grows, infrastructure ages, and sociopolitical values alter them. In order to systematically study changes over time, the concept of “urban evolution” was proposed. It allows urban planning, management, and restoration to move beyond reactive management to predictive management based on past observations of consistent patterns. Here, we define and review a glossary of core concepts for studying urban evolution, which includes the mechanisms of urban selective pressure and urban adaptation. Urban selective pressure is an environmental or societal driver contributing to urban adaptation. Urban adaptation is the sequential process by which an urban structure, function, or services becomes more fitted to its changing environment or human choices. The role of water is vital to driving urban evolution as demonstrated by historical changes in drainage, sewage flows, hydrologic pulses, and long-term chemistry. In the current paper, we show how hydrologic traits evolve across successive generations of urban ecosystems via shifts in selective pressures and adaptations over time. We explore multiple empirical examples including evolving: (1 urban drainage from stream burial to stormwater management; (2 sewage flows and water quality in response to wastewater treatment; (3 amplification of hydrologic pulses due to the interaction between urbanization and climate variability; and (4 salinization and alkalinization of fresh water due to human inputs and accelerated weathering. Finally, we propose a new conceptual model for the evolution of urban waters from the Industrial Revolution to the present day based on empirical trends and historical information. Ultimately, we propose that water itself is a critical driver of urban evolution that forces urban adaptation, which transforms the structure, function, and services of urban

  18. Effective Strategies for Teaching Evolution: The Primary Evolution Project

    Science.gov (United States)

    Hatcher, Chris

    2015-01-01

    When Chris Hatcher joined the Primary Evolution Project team at the University of Reading, his goal was to find effective strategies to teach evolution in a way that keeps children engaged and enthused. Hatcher has collaborated with colleagues at the University's Institute of Education to break the evolution unit down into distinct topics and…

  19. Viral Evolution Core | FNLCR Staging

    Science.gov (United States)

    Brandon F. Keele, Ph.D. PI/Senior Principal Investigator, Retroviral Evolution Section Head, Viral Evolution Core Leidos Biomedical Research, Inc. Frederick National Laboratory for Cancer Research Frederick, MD 21702-1201 Tel: 301-846-173

  20. The physics of evolution

    Science.gov (United States)

    Eigen, Manfred

    1988-12-01

    The Darwinian concept of evolution through natural selection has been revised and put on a solid physical basis, in a form which applies to self-replicable macromolecules. Two new concepts are introduced: sequence space and quasi-species. Evolutionary change in the DNA- or RNA-sequence of a gene can be mapped as a trajectory in a sequence space of dimension ν, where ν corresponds to the number of changeable positions in the genomic sequence. Emphasis, however, is shifted from the single surviving wildtype, a single point in the sequence space, to the complex structure of the mutant distribution that constitutes the quasi-species. Selection is equivalent to an establishment of the quasi-species in a localized region of sequence space, subject to threshold conditions for the error rate and sequence length. Arrival of a new mutant may violate the local threshold condition and thereby lead to a displacement of the quasi-species into a different region of sequence space. This transformation is similar to a phase transition; the dynamical equations that describe the quase-species have been shown to be analogous to those of the two-dimensional Ising model of ferromagnetism. The occurrence of a selectively advantageous mutant is biased by the particulars of the quasi-species distribution, whose mutants are populated according to their fitness relative to that of the wild-type. Inasmuch as fitness regions are connected (like mountain ridges) the evolutionary trajectory is guided to regions of optimal fitness. Evolution experiments in test tubes confirm this modification of the simple chance and law nature of the Darwinian concept. The results of the theory can also be applied to the construction of a machine that provides optimal conditions for a rapid evolution of functionally active macromolecules. An introduction to the physics of molecular evolution by the author has appeared recently.1 Detailed studies of the kinetics and mechanisms of replication of RNA, the most

  1. Swaddling: A Systematic Review

    NARCIS (Netherlands)

    van Sleuwen, Bregje E.; Engelberts, Adèle C.; Boere-Boonekamp, Magdalena M.; Kuis, Wietse; Schulpen, Tom W.J.

    2007-01-01

    Swaddling was an almost universal child-care practice before the 18th century. It is still tradition in certain parts of the Middle East and is gaining popularity in the United Kingdom, the United States, and the Netherlands to curb excessive crying. We have systematically reviewed all articles on

  2. Systematic, Cooperative Evaluation.

    Science.gov (United States)

    Nassif, Paula M.

    Evaluation procedures based on a systematic evaluation methodology, decision-maker validity, new measurement and design techniques, low cost, and a high level of cooperation on the part of the school staff were used in the assessment of a public school mathematics program for grades 3-8. The mathematics curriculum was organized into Spirals which…

  3. Swaddling : A systematic review

    NARCIS (Netherlands)

    van Sleuwen, Bregje E.; Engelberts, Adele C.; Boere-Boonekamp, Magda M.; Kuis, Wietse; Schulpen, Tom W. J.; L'Hoir, Monique P.

    2007-01-01

    Swaddling was an almost universal child-care practice before the 18th century. It is still tradition in certain parts of the Middle East and is gaining popularity in the United Kingdom, the United States, and the Netherlands to curb excessive crying. We have systematically reviewed all articles on

  4. Serbia : Systematic Country Diagnostic

    OpenAIRE

    World Bank Group

    2015-01-01

    This Systematic Country Diagnostic (SCD) aims to identify the major constraints on and opportunities for sustaining poverty reduction and shared prosperity in Serbia. The SCD serves as the analytic foundation on which the World Bank Group and the Government of Serbia will define a new Country Partnership Framework for FY2016 to FY2020. It is based on the best possible analysis, drawing on ...

  5. Toward Documentation of Program Evolution

    DEFF Research Database (Denmark)

    Vestdam, Thomas; Nørmark, Kurt

    2005-01-01

    The documentation of a program often falls behind the evolution of the program source files. When this happens it may be attractive to shift the documentation mode from updating the documentation to documenting the evolution of the program. This paper describes tools that support the documentatio....... It is concluded that our approach can help revitalize older documentation, and that discovery of the fine grained program evolution steps help the programmer in documenting the evolution of the program....

  6. Expanding the Understanding of Evolution

    Science.gov (United States)

    Musante, Susan

    2011-01-01

    Originally designed for K-12 teachers, the Understanding Evolution (UE) Web site ("www.understandingevolution.org") is a one-stop shop for all of a teacher's evolution education needs, with lesson plans, teaching tips, lists of common evolution misconceptions, and much more. However, during the past five years, the UE project team learned that…

  7. Inlet Geomorphology Evolution Work Unit

    Science.gov (United States)

    2015-10-30

    Coastal Inlets Research Program Inlet Geomorphology Evolution Work Unit The Inlet Geomorphology Evolution work unit of the CIRP develops methods...morphologic response. Presently, the primary tool of the Inlet Geomorphology Evolution work unit is the Sediment Mobility Tool (SMT), which allows the user

  8. Evolution and transitions in complexity

    NARCIS (Netherlands)

    Jagers op Akkerhuis, Gerard A.J.M.

    2016-01-01

    This book discusses several recent theoretic advancements in interdisciplinary and transdisciplinary integration in the field of evolution. While exploring novel views, the text maintains a close link with one of the most broadly held views on evolution, namely that of "Darwinian evolution." This

  9. Quality of systematic reviews in pediatric oncology - A systematic review

    NARCIS (Netherlands)

    Lundh, Andreas; Knijnenburg, Sebastiaan L.; Jørgensen, Anders W.; van Dalen, Elvira C.; Kremer, Leontien C. M.

    2009-01-01

    Background: To ensure evidence-based decision making in pediatric oncology systematic reviews are necessary. The objective of our study was to evaluate the methodological quality of all currently existing systematic reviews in pediatric oncology. Methods: We identified eligible systematic reviews

  10. The evolution of dinosaurs.

    Science.gov (United States)

    Sereno, P C

    1999-06-25

    The ascendancy of dinosaurs on land near the close of the Triassic now appears to have been as accidental and opportunistic as their demise and replacement by therian mammals at the end of the Cretaceous. The dinosaurian radiation, launched by 1-meter-long bipeds, was slower in tempo and more restricted in adaptive scope than that of therian mammals. A notable exception was the evolution of birds from small-bodied predatory dinosaurs, which involved a dramatic decrease in body size. Recurring phylogenetic trends among dinosaurs include, to the contrary, increase in body size. There is no evidence for co-evolution between predators and prey or between herbivores and flowering plants. As the major land masses drifted apart, dinosaurian biogeography was molded more by regional extinction and intercontinental dispersal than by the breakup sequence of Pangaea.

  11. Evolution of energy structures

    International Nuclear Information System (INIS)

    Nifenecker, H.

    2005-01-01

    Because of the big inertia and long time constants of energy systems, their long-time behaviour is mainly determined by their present day state and by the trends of their recent evolution. For this reason, it is of prime importance to foresee the evolution of the different energy production sources which may play an important role in the future. A status of the world energy consumption and production is made first using the energy statistics of the IEA. Then, using the trends observed since 1973, the consequences of a simple extrapolation of these trends is examined. Finally, the scenarios of forecasting of energy structures, like those supplied by the International institute for applied systems analysis (IIASA) are discussed. (J.S.)

  12. Evolution of Mobile Applications

    Directory of Open Access Journals (Sweden)

    Phongtraychack Anachack

    2018-01-01

    Full Text Available Currently, we can see the rapid evolution of mobile technology, which involves mobile communication, mobile hardware, and mobile software. Features of mobile phones largely depend on software. In contemporary information and communication age [1–4], mobile application is one of the most concerned and rapidly developing areas. At the same time, the development of mobile application undergoes great changes with the introduction of new software, service platforms and software development kits (SDK. These changes lead to appearance of many new service platforms such as Google with Android and Apple with iOS. This article presents the information about the evolution of mobile application, gives some statistical data on the past and present situation, demonstrates how individual users of mobile devices can benefit, and shows how mobile applications affect society from the ethical perspective.

  13. Evolution to Autonomy

    Directory of Open Access Journals (Sweden)

    Horace Lockwood Fairlamb

    2007-08-01

    Full Text Available Since both modern moral theory and evolutionary theory arose in the shadow of Newtonian and Humean conceptions of nature, debates about evolutionary ethics have typically been vexed by deeper problems with the nature of evolution itself as well as meta-ethical questions about the link between facts and values. Humean skepticism and mechanistic selectionism have recently coincided in postmodern attacks on essentialism,on meta-narratives of progress, on models of human nature, and on moral collectivism. Against this most recent wave of skepticism, however, contemporary reconstructions of evolution in light of complex systems science suggest useful ways of reinterpreting both evolutionary causation, the biology of human nature, and their implications for ethics.

  14. Galaxy formation and evolution

    CERN Document Server

    Mo, Houjun; White, Simon

    2010-01-01

    The rapidly expanding field of galaxy formation lies at the interface between astronomy, particle physics, and cosmology. Covering diverse topics from these disciplines, all of which are needed to understand how galaxies form and evolve, this book is ideal for researchers entering the field. Individual chapters explore the evolution of the Universe as a whole and its particle and radiation content; linear and nonlinear growth of cosmic structure; processes affecting the gaseous and dark matter components of galaxies and their stellar populations; the formation of spiral and elliptical galaxies; central supermassive black holes and the activity associated with them; galaxy interactions; and the intergalactic medium. Emphasizing both observational and theoretical aspects, this book provides a coherent introduction for astronomers, cosmologists, and astroparticle physicists to the broad range of science underlying the formation and evolution of galaxies.

  15. Instability and star evolution

    International Nuclear Information System (INIS)

    Mirzoyan, L.V.

    1981-01-01

    The observational data are discussed which testify that the phenomena of dynamical instability of stars and stellar systems are definite manifestations of their evolution. The study of these phenomena has shown that the instability is a regular phase of stellar evolution. It has resulted in the recognition of the most important regularities of the process of star formation concerning its nature. This became possible due to the discovery in 1947 of stellar associations in our Galaxy. The results of the study of the dynamical instability of stellar associations contradict the predictions of classical hypothesis of stellar condensation. These data supplied a basis for a new hypothesis on the formation of stars and nebulae by the decay of superdense protostars [ru

  16. Evolution of clustered storage

    CERN Multimedia

    CERN. Geneva; Van de Vyvre, Pierre

    2007-01-01

    The session actually featured two presentations: * Evolution of clustered storage by Lance Hukill, Quantum Corporation * ALICE DAQ - Usage of a Cluster-File System: Quantum StorNext by Pierre Vande Vyvre, CERN-PH the second one prepared at short notice by Pierre (thanks!) to present how the Quantum technologies are being used in the ALICE experiment. The abstract to Mr Hukill's follows. Clustered Storage is a technology that is driven by business and mission applications. The evolution of Clustered Storage solutions starts first at the alignment between End-users needs and Industry trends: * Push-and-Pull between managing for today versus planning for tomorrow * Breaking down the real business problems to the core applications * Commoditization of clients, servers, and target devices * Interchangeability, Interoperability, Remote Access, Centralized control * Oh, and yes, there is a budget and the "real world" to deal with This presentation will talk through these needs and trends, and then ask the question, ...

  17. Epigenetics and brain evolution.

    Science.gov (United States)

    Keverne, Eric B

    2011-04-01

    Fundamental aspects of mammalian brain evolution occurred in the context of viviparity and placentation brought about by the epigenetic regulation of imprinted genes. Since the fetal placenta hormonally primes the maternal brain, two genomes in one individual are transgenerationally co-adapted to ensure maternal care and nurturing. Advanced aspects of neocortical brain evolution has shown very few genetic changes between monkeys and humans. Although these lineages diverged at approximately the same time as the rat and mouse (20 million years ago), synonymous sequence divergence between the rat and mouse is double that when comparing monkey with human sequences. Paradoxically, encephalization of rat and mouse are remarkably similar, while comparison of the human and monkey shows the human cortex to be three times the size of the monkey. This suggests an element of genetic stability between the brains of monkey and man with a greater emphasis on epigenetics providing adaptable variability.

  18. The metaphysics of evolution.

    Science.gov (United States)

    Dupré, John

    2017-10-06

    This paper briefly describes process metaphysics, and argues that it is better suited for describing life than the more standard thing, or substance, metaphysics. It then explores the implications of process metaphysics for conceptualizing evolution. After explaining what it is for an organism to be a process, the paper takes up the Hull/Ghiselin thesis of species as individuals and explores the conditions under which a species or lineage could constitute an individual process. It is argued that only sexual species satisfy these conditions, and that within sexual species the degree of organization varies. This, in turn, has important implications for species' evolvability. One important moral is that evolution will work differently in different biological domains.

  19. Kamikazes and cultural evolution.

    Science.gov (United States)

    Allen-Hermanson, Sean

    2017-02-01

    Is cultural evolution needed to explain altruistic selfsacrifice? Some contend that cultural traits (e.g. beliefs, behaviors, and for some "memes") replicate according to selection processes that have "floated free" from biology. One test case is the example of suicide kamikaze attacks in wartime Japan. Standard biological mechanisms-such as reciprocal altruism and kin selection-might not seem to apply here: The suicide pilots did not act on the expectation that others would reciprocate, and they were supposedly sacrificing themselves for country and emperor, not close relatives. Yet an examination of both the historical record and the demands of evolutionary theory suggest the kamikaze phenomenon does not cry out for explanation in terms of a special non-biological selection process. This weakens the case for cultural evolution, and has interesting implications for our understanding of altruistic self-sacrifice. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Chromosomal Evolution in Chiroptera

    OpenAIRE

    Sotero-Caio, Cibele G.; Baker, Robert J.; Volleth, Marianne

    2017-01-01

    Chiroptera is the second largest order among mammals, with over 1300 species in 21 extant families. The group is extremely diverse in several aspects of its natural history, including dietary strategies, ecology, behavior and morphology. Bat genomes show ample chromosome diversity (from 2n = 14 to 62). As with other mammalian orders, Chiroptera is characterized by clades with low, moderate and extreme chromosomal change. In this article, we will discuss trends of karyotypic evolution within d...

  1. Software evolution and maintenance

    CERN Document Server

    Tripathy, Priyadarshi

    2014-01-01

    Software Evolution and Maintenance: A Practitioner's Approach is an accessible textbook for students and professionals, which collates the advances in software development and provides the most current models and techniques in maintenance.Explains two maintenance standards: IEEE/EIA 1219 and ISO/IEC14764Discusses several commercial reverse and domain engineering toolkitsSlides for instructors are available onlineInformation is based on the IEEE SWEBOK (Software Engineering Body of Knowledge)

  2. Electroweak evolution equations

    International Nuclear Information System (INIS)

    Ciafaloni, Paolo; Comelli, Denis

    2005-01-01

    Enlarging a previous analysis, where only fermions and transverse gauge bosons were taken into account, we write down infrared-collinear evolution equations for the Standard Model of electroweak interactions computing the full set of splitting functions. Due to the presence of double logs which are characteristic of electroweak interactions (Bloch-Nordsieck violation), new infrared singular splitting functions have to be introduced. We also include corrections related to the third generation Yukawa couplings

  3. Embodied artificial evolution

    OpenAIRE

    Eiben, A. E.; Kernbach, S.; Haasdijk, Evert

    2012-01-01

    Evolution is one of the major omnipresent powers in the universe that has been studied for about two centuries. Recent scientific and technical developments make it possible to make the transition from passively understanding to actively using evolutionary processes. Today this is possible in Evolutionary Computing, where human experimenters can design and manipulate all components of evolutionary processes in digital spaces. We argue that in the near future it will be possible to implement a...

  4. Evolution of microbial pathogens.

    OpenAIRE

    Morschhäuser, J; Köhler, G; Ziebuhr, W; Blum-Oehler, G; Dobrindt, U; Hacker, J

    2000-01-01

    Various genetic mechanisms including point mutations, genetic rearrangements and lateral gene transfer processes contribute to the evolution of microbes. Long-term processes leading to the development of new species or subspecies are termed macroevolution, and short-term developments, which occur during days or weeks, are considered as microevolution. Both processes, macro- and microevolution need horizontal gene transfer, which is particularly important for the development of pathogenic micr...

  5. Ontology evolution in physics

    OpenAIRE

    Chan, Michael

    2013-01-01

    With the advent of reasoning problems in dynamic environments, there is an increasing need for automated reasoning systems to automatically adapt to unexpected changes in representations. In particular, the automation of the evolution of their ontologies needs to be enhanced without substantially sacrificing expressivity in the underlying representation. Revision of beliefs is not enough, as adding to or removing from beliefs does not change the underlying formal language. Gene...

  6. On protostellar evolution

    International Nuclear Information System (INIS)

    Westbrook, C.K.; Tarter, C.B.

    1975-01-01

    An investigation of the evolution of spherically symmetric protostars with initial masses in the range 0.1less than or equal toM/M/sub sun/less than or equal to50 has been carried out. In order to perform the calculations, a numerical technique has been developed in which rapid dynamical motions in one region of the star and quasi-static evolution in another region can be simultaneously computed. The general evolutionary features are similar to those found by other workers: an initial free-fall collapse is followed by the creation of a core in hydrostatic equilibrium, and the core's subsequent accretion of the surrounding envelope. However, our final hydrostatic-equilibrium configurations have radii large compared with those of the protostellar models of Larson (but in reasonable agreement with those of conventional pre-main-sequence models). For low-mass protostars (Mless than or equal toM/sub sun/) the luminosity remains relatively small until late evolutionary times and the evolution is very sensitive to the treatment of convective energy transport. For large-mass protostars (Mgreater than or equal to3M/sub sun/) a convective phase never exists, and a fraction (increasing with mass) of the initial mass is ejected by the combined effects of heating and radiation pressure in the envelope

  7. ENVIRONMENT AND PROTOSTELLAR EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yichen [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Tan, Jonathan C., E-mail: yczhang.astro@gmail.com [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States)

    2015-04-01

    Even today in our Galaxy, stars form from gas cores in a variety of environments, which may affect the properties of the resulting star and planetary systems. Here, we study the role of pressure, parameterized via ambient clump mass surface density, on protostellar evolution and appearance, focusing on low-mass Sun-like stars and considering a range of conditions from relatively low pressure filaments in Taurus, to intermediate pressures of cluster-forming clumps like the Orion Nebula Cluster, to very high pressures that may be found in the densest infrared dark clouds or in the Galactic center. We present unified analytic and numerical models for the collapse of prestellar cores, accretion disks, protostellar evolution, and bipolar outflows, coupled with radiative transfer calculations and a simple astrochemical model to predict CO gas-phase abundances. Prestellar cores in high-pressure environments are smaller and denser and thus collapse with higher accretion rates and efficiencies, resulting in higher luminosity protostars with more powerful outflows. The protostellar envelope is heated to warmer temperatures, affecting infrared morphologies (and thus classification) and astrochemical processes like CO depletion onto dust grain ice mantles (and thus CO morphologies). These results have general implications for star and planet formation, especially via their effect on astrochemical and dust grain evolution during infall to and through protostellar accretion disks.

  8. Frost evolution in tailings

    International Nuclear Information System (INIS)

    1991-04-01

    A review was carried out on the physical and thermal mechanisms of permafrost evaluation in soils and uranium tailings. The primary mechanism controlling permafrost evolution is conductive heat transfer with the latent heat of fusion of water being liberated as phase change occurs. Depending on the soil properties and freezing rate, pore water can be expelled from the frost front or pore water can migrate towards the frost front. Solute redistribution may occur as the frost front penetrates into the soil. The rate of frost penetration is a function of the thermal properties of the tailings and the climatic conditions. Computer modelling programmes capable of modelling permafrost evolution were reviewed. The GEOTHERM programme was selected as being the most appropriate for this study. The GEOTHERM programme uses the finite element method of thermal analysis. The ground surface temperature is determined by solving the energy balance equations a the ground surface. The GEOTHERM programme was used to simulate the permafrost evolution in the Key Lake Mine tailings located in north central Saskatchewan. The analyses indicated that the existing frozen zones in the tailing pond will eventually thaw if an average snow depth covers the tailings. Hundreds of years are required to thaw the tailings. If minimal snow cover is present the extent of the frozen zone in the tailings will increase

  9. The evolution of teaching.

    Science.gov (United States)

    Fogarty, L; Strimling, P; Laland, K N

    2011-10-01

    Teaching, alongside imitation, is widely thought to underlie the success of humanity by allowing high-fidelity transmission of information, skills, and technology between individuals, facilitating both cumulative knowledge gain and normative culture. Yet, it remains a mystery why teaching should be widespread in human societies but extremely rare in other animals. We explore the evolution of teaching using simple genetic models in which a single tutor transmits adaptive information to a related pupil at a cost. Teaching is expected to evolve where its costs are outweighed by the inclusive fitness benefits that result from the tutor's relatives being more likely to acquire the valuable information. We find that teaching is not favored where the pupil can easily acquire the information on its own, or through copying others, or for difficult to learn traits, where teachers typically do not possess the information to pass on to relatives. This leads to a narrow range of traits for which teaching would be efficacious, which helps to explain the rarity of teaching in nature, its unusual distribution, and its highly specific nature. Further models that allow for cumulative cultural knowledge gain suggest that teaching evolved in humans because cumulative culture renders otherwise difficult-to-acquire valuable information available to teach. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

  10. Consciousness and biological evolution.

    Science.gov (United States)

    Lindahl, B I

    1997-08-21

    It has been suggested that if the preservation and development of consciousness in the biological evolution is a result of natural selection, it is plausible that consciousness not only has been influenced by neural processes, but has had a survival value itself; and it could only have had this, if it had also been efficacious. This argument for mind-brain interaction is examined, both as the argument has been developed by William James and Karl Popper and as it has been discussed by C.D. Broad. The problem of identifying mental phenomena with certain neural phenomena is also addressed. The main conclusion of the analysis is that an explanation of the evolution of consciousness in Darwinian terms of natural selection does not rule out that consciousness may have evolved as a mere causally inert effect of the evolution of the nervous system, or that mental phenomena are identical with certain neural phenomena. However, the interactionistic theory still seems, more plausible and more fruitful for other reasons brought up in the discussion.

  11. Reconstructing human evolution

    CERN Multimedia

    AUTHOR|(CDS)2074069

    1999-01-01

    One can reconstruct human evolution using modern genetic data and models based on the mathematical theory of evolution and its four major factors : mutation, natural selection, statistical fluctuations in finite populations (random genetic drift), and migration. Archaeology gives some help on the major dates and events of the process. Chances of studying ancient DNA are very limited but there have been a few successful results. Studying DNA instead of proteins, as was done until a few years ago, and in particular the DNA of mitochondria and of the Y chromosome which are transmitted, respectively, by the maternal line and the paternal line, has greatly simplified the analysis. It is now possible to carry the analysis on individuals, while earlier studies were of necessity based on populations. Also the evolution of ÒcultureÓ (i.e. what we learn from others), in particular that of languages, gives some help and can be greatly enlightened by genetic studies. Even though it is largely based on mechanisms of mut...

  12. Analytic Theology as Systematic Theology

    OpenAIRE

    Crisp Oliver D.

    2017-01-01

    It is often said that analytic theology is not really systematic theology; it is something else entirely. However, specifying what this “something else” amounts to has proven a little more difficult. In this article I argue that analytic theology may be a species of systematic theology. I show that there is no agreed view on the nature of systematic theology amongst several leading practitioners of systematic theology by comparing the work of John Webster, Brian Gerrish, and Gordon Kaufman. I...

  13. Evolution of the Internet and its cores

    International Nuclear Information System (INIS)

    Zhang Guoqing; Zhang Guoqiang; Yang Qingfeng; Cheng Suqi; Zhou Tao

    2008-01-01

    In this paper, we empirically study the evolution of large scale Internet topology at the autonomous system (AS) level. The network size grows in an exponential form, obeying the famous Moore's law. We theoretically predict that the size of the AS-level Internet will double every 5.32 years. We apply the k-core decomposition method on the real Internet, and find that the size of a k-core with larger k is nearly stable over time. In addition, the maximal coreness is very stable after 2003. In contrast to the predictions of most previous models, the maximal degree of the Internet is also relatively stable versus time. We use the edge-exchange operation to obtain the randomized networks with the same degree sequence. A systematical comparison is drawn, indicating that the real Internet is more loosely connected, and both the full Internet and the nucleus are more disassortative than their randomized versions.

  14. Evolution of the Internet and its cores

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Guoqing; Zhang Guoqiang; Yang Qingfeng; Cheng Suqi [Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100190 (China); Zhou Tao [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)], E-mail: gqzhang@ict.ac.cn, E-mail: zhutou@ustc.edu

    2008-12-15

    In this paper, we empirically study the evolution of large scale Internet topology at the autonomous system (AS) level. The network size grows in an exponential form, obeying the famous Moore's law. We theoretically predict that the size of the AS-level Internet will double every 5.32 years. We apply the k-core decomposition method on the real Internet, and find that the size of a k-core with larger k is nearly stable over time. In addition, the maximal coreness is very stable after 2003. In contrast to the predictions of most previous models, the maximal degree of the Internet is also relatively stable versus time. We use the edge-exchange operation to obtain the randomized networks with the same degree sequence. A systematical comparison is drawn, indicating that the real Internet is more loosely connected, and both the full Internet and the nucleus are more disassortative than their randomized versions.

  15. Molecular systematics of the Canidae.

    Science.gov (United States)

    Wayne, R K; Geffen, E; Girman, D J; Koepfli, K P; Lau, L M; Marshall, C R

    1997-12-01

    Despite numerous systematic studies, the relationships among many species within the dog family, Canidae, remain unresolved. Two problems of broad evolutionary significance are the origins of the taxonomically rich canidae fauna of South America and the development in three species of the trenchant heel, a unique meat-cutting blade on the lower first molar. The first problem is of interest because the fossil record provides little evidence for the origins of divergent South American species such as the maned wolf and the bush dog. The second issue is problematic because the trenchant heel, although complex in form, may have evolved independently to assist in the processing of meat. We attempted to resolve these two issues and five other specific taxonomic controversies by phylogenetic analysis of 2,001 base pairs of mitochondrial DNA (mtDNA) sequence data from 23 canidae species. The mtDNA tree topology, coupled with data from the fossil record, and estimates of rates of DNA sequence divergence suggest at least three and possibly four North American invasions of South America. This result implies that an important chapter in the evolution of modern canids remains to be discovered in the fossil record and that the South American canidae endemism is as much the result of extinction outside of South America as it is due to speciation within South America. The origin of the trenchant heel is not well resolved by our data, although the maximum parsimony tree is weakly consistent with a single origin followed by multiple losses of the character in several extant species. A combined analysis of the mtDNA data and published morphological data provides unexpected support for a monophyletic South American canidae clade. However, the homogeneity partition tests indicate significant heterogeneity between the two data sets.

  16. Computational aspects of systematic biology.

    Science.gov (United States)

    Lilburn, Timothy G; Harrison, Scott H; Cole, James R; Garrity, George M

    2006-06-01

    We review the resources available to systematic biologists who wish to use computers to build classifications. Algorithm development is in an early stage, and only a few examples of integrated applications for systematic biology are available. The availability of data is crucial if systematic biology is to enter the computer age.

  17. Systematic Quality Work in Preschool

    Science.gov (United States)

    Sheridan, Sonja; Williams, Pia; Sandberg, Anette

    2013-01-01

    The purpose of this study was to investigate the meaning that Swedish preschool teachers ascribe to systematic quality work. In Sweden, all preschools are required to work systematically with quality issues. This involves several interdependent steps that follow each other in a specific order. Although the concept of systematic quality work might…

  18. Anmeldelse af Evolution, Literature and Film

    DEFF Research Database (Denmark)

    Grodal, Torben Kragh

    2011-01-01

    Diskussion af basisproblemer i evolutionær fiktionsteori med udgangspunkt i en anmeldelse af Evolution, Literature and Film......Diskussion af basisproblemer i evolutionær fiktionsteori med udgangspunkt i en anmeldelse af Evolution, Literature and Film...

  19. Constrained evolution in numerical relativity

    Science.gov (United States)

    Anderson, Matthew William

    The strongest potential source of gravitational radiation for current and future detectors is the merger of binary black holes. Full numerical simulation of such mergers can provide realistic signal predictions and enhance the probability of detection. Numerical simulation of the Einstein equations, however, is fraught with difficulty. Stability even in static test cases of single black holes has proven elusive. Common to unstable simulations is the growth of constraint violations. This work examines the effect of controlling the growth of constraint violations by solving the constraints periodically during a simulation, an approach called constrained evolution. The effects of constrained evolution are contrasted with the results of unconstrained evolution, evolution where the constraints are not solved during the course of a simulation. Two different formulations of the Einstein equations are examined: the standard ADM formulation and the generalized Frittelli-Reula formulation. In most cases constrained evolution vastly improves the stability of a simulation at minimal computational cost when compared with unconstrained evolution. However, in the more demanding test cases examined, constrained evolution fails to produce simulations with long-term stability in spite of producing improvements in simulation lifetime when compared with unconstrained evolution. Constrained evolution is also examined in conjunction with a wide variety of promising numerical techniques, including mesh refinement and overlapping Cartesian and spherical computational grids. Constrained evolution in boosted black hole spacetimes is investigated using overlapping grids. Constrained evolution proves to be central to the host of innovations required in carrying out such intensive simulations.

  20. An overview of systematic review.

    Science.gov (United States)

    Baker, Kathy A; Weeks, Susan Mace

    2014-12-01

    Systematic review is an invaluable tool for the practicing clinician. A well-designed systematic review represents the latest and most complete information available on a particular topic or intervention. This article highlights the key elements of systematic review, what it is and is not, and provides an overview of several reputable organizations supporting the methodological development and conduct of systematic review. Important aspects for evaluating the quality of a systematic review are also included. Copyright © 2014 American Society of PeriAnesthesia Nurses. Published by Elsevier Inc. All rights reserved.

  1. NRC systematic evaluation program: seismic review

    International Nuclear Information System (INIS)

    Levin, H.A.

    1980-01-01

    The NRC Systematic Evaluation Program is currently making an assessment of the seismic design safety of 11 older nuclear power plant facilities. The general review philosophy and review criteria relative to seismic input, structural response, and equipment functionability are presented, including the rationale for the development of these guidelines considering the significant evolution of seismic design criteria since these plants were originally licensed. Technical approaches thought more realistic in light of current knowledge are utilized. Initial findings for plants designed to early seismic design procedures suggest that with minor exceptions, these plants possess adequate seismic design margins when evaluated against the intent of current criteria. However, seismic qualification of electrical equipment has been identified as a subject which requires more in-depth evaluation

  2. Multilocus genetics to reconstruct aeromonad evolution

    Directory of Open Access Journals (Sweden)

    Roger Frédéric

    2012-04-01

    Full Text Available Abstract Background Aeromonas spp. are versatile bacteria that exhibit a wide variety of lifestyles. In an attempt to improve the understanding of human aeromonosis, we investigated whether clinical isolates displayed specific characteristics in terms of genetic diversity, population structure and mode of evolution among Aeromonas spp. A collection of 195 Aeromonas isolates from human, animal and environmental sources was therefore genotyped using multilocus sequence analysis (MLSA based on the dnaK, gltA, gyrB, radA, rpoB, tsf and zipA genes. Results The MLSA showed a high level of genetic diversity among the population, and multilocus-based phylogenetic analysis (MLPA revealed 3 major clades: the A. veronii, A. hydrophila and A. caviae clades, among the eleven clades detected. Lower genetic diversity was observed within the A. caviae clade as well as among clinical isolates compared to environmental isolates. Clonal complexes, each of which included a limited number of strains, mainly corresponded to host-associated subsclusters of strains, i.e., a fish-associated subset within A. salmonicida and 11 human-associated subsets, 9 of which included only disease-associated strains. The population structure was shown to be clonal, with modes of evolution that involved mutations in general and recombination events locally. Recombination was detected in 5 genes in the MLSA scheme and concerned approximately 50% of the STs. Therefore, these recombination events could explain the observed phylogenetic incongruities and low robustness. However, the MLPA globally confirmed the current systematics of the genus Aeromonas. Conclusions Evolution in the genus Aeromonas has resulted in exceptionally high genetic diversity. Emerging from this diversity, subsets of strains appeared to be host adapted and/or “disease specialized” while the A. caviae clade displayed an atypical tempo of evolution among aeromonads. Considering that A. salmonicida has been

  3. Evolution of homeobox genes.

    Science.gov (United States)

    Holland, Peter W H

    2013-01-01

    Many homeobox genes encode transcription factors with regulatory roles in animal and plant development. Homeobox genes are found in almost all eukaryotes, and have diversified into 11 gene classes and over 100 gene families in animal evolution, and 10 to 14 gene classes in plants. The largest group in animals is the ANTP class which includes the well-known Hox genes, plus other genes implicated in development including ParaHox (Cdx, Xlox, Gsx), Evx, Dlx, En, NK4, NK3, Msx, and Nanog. Genomic data suggest that the ANTP class diversified by extensive tandem duplication to generate a large array of genes, including an NK gene cluster and a hypothetical ProtoHox gene cluster that duplicated to generate Hox and ParaHox genes. Expression and functional data suggest that NK, Hox, and ParaHox gene clusters acquired distinct roles in patterning the mesoderm, nervous system, and gut. The PRD class is also diverse and includes Pax2/5/8, Pax3/7, Pax4/6, Gsc, Hesx, Otx, Otp, and Pitx genes. PRD genes are not generally arranged in ancient genomic clusters, although the Dux, Obox, and Rhox gene clusters arose in mammalian evolution as did several non-clustered PRD genes. Tandem duplication and genome duplication expanded the number of homeobox genes, possibly contributing to the evolution of developmental complexity, but homeobox gene loss must not be ignored. Evolutionary changes to homeobox gene expression have also been documented, including Hox gene expression patterns shifting in concert with segmental diversification in vertebrates and crustaceans, and deletion of a Pitx1 gene enhancer in pelvic-reduced sticklebacks. WIREs Dev Biol 2013, 2:31-45. doi: 10.1002/wdev.78 For further resources related to this article, please visit the WIREs website. The author declares that he has no conflicts of interest. Copyright © 2012 Wiley Periodicals, Inc.

  4. Evolution of sexual asymmetry

    Directory of Open Access Journals (Sweden)

    Hoekstra Rolf F

    2004-09-01

    Full Text Available Abstract Background The clear dominance of two-gender sex in recent species is a notorious puzzle of evolutionary theory. It has at least two layers: besides the most fundamental and challenging question why sex exists at all, the other part of the problem is equally perplexing but much less studied. Why do most sexual organisms use a binary mating system? Even if sex confers an evolutionary advantage (through whatever genetic mechanism, why does it manifest that advantage in two, and exactly two, genders (or mating types? Why not just one, and why not more than two? Results Assuming that sex carries an inherent fitness advantage over pure clonal multiplication, we attempt to give a feasible solution to the problem of the evolution of dimorphic sexual asymmetry as opposed to monomorphic symmetry by using a spatial (cellular automaton model and its non-spatial (mean-field approximation. Based on a comparison of the spatial model to the mean-field approximation we suggest that spatial population structure must have played a significant role in the evolution of mating types, due to the largely clonal (self-aggregated spatial distribution of gamete types, which is plausible in aquatic habitats for physical reasons, and appears to facilitate the evolution of a binary mating system. Conclusions Under broad ecological and genetic conditions the cellular automaton predicts selective removal from the population of supposedly primitive gametes that are able to mate with their own type, whereas the non-spatial model admits coexistence of the primitive type and the mating types. Thus we offer a basically ecological solution to a theoretical problem that earlier models based on random gamete encounters had failed to resolve.

  5. Evolution before genes

    Directory of Open Access Journals (Sweden)

    Vasas Vera

    2012-01-01

    Full Text Available Abstract Background Our current understanding of evolution is so tightly linked to template-dependent replication of DNA and RNA molecules that the old idea from Oparin of a self-reproducing 'garbage bag' ('coacervate' of chemicals that predated fully-fledged cell-like entities seems to be farfetched to most scientists today. However, this is exactly the kind of scheme we propose for how Darwinian evolution could have occurred prior to template replication. Results We cannot confirm previous claims that autocatalytic sets of organic polymer molecules could undergo evolution in any interesting sense by themselves. While we and others have previously imagined inhibition would result in selectability, we found that it produced multiple attractors in an autocatalytic set that cannot be selected for. Instead, we discovered that if general conditions are satisfied, the accumulation of adaptations in chemical reaction networks can occur. These conditions are the existence of rare reactions producing viable cores (analogous to a genotype, that sustains a molecular periphery (analogous to a phenotype. Conclusions We conclude that only when a chemical reaction network consists of many such viable cores, can it be evolvable. When many cores are enclosed in a compartment there is competition between cores within the same compartment, and when there are many compartments, there is between-compartment competition due to the phenotypic effects of cores and their periphery at the compartment level. Acquisition of cores by rare chemical events, and loss of cores at division, allows macromutation, limited heredity and selectability, thus explaining how a poor man's natural selection could have operated prior to genetic templates. This is the only demonstration to date of a mechanism by which pre-template accumulation of adaptation could occur. Reviewers This article was reviewed by William Martin and Eugene Koonin.

  6. Glucosinolate structures in evolution.

    Science.gov (United States)

    Agerbirk, Niels; Olsen, Carl Erik

    2012-05-01

    By 2000, around 106 natural glucosinolates (GSLs) were probably documented. In the past decade, 26 additional natural GSL structures have been elucidated and documented. Hence, the total number of documented GSLs from nature by 2011 can be estimated to around 132. A considerable number of additional suggested structures are concluded not to be sufficiently documented. In many cases, NMR spectroscopy would have provided the missing structural information. Of the GSLs documented in the past decade, several are of previously unexpected structures and occur at considerable levels. Most originate from just four species: Barbarea vulgaris, Arabidopsis thaliana, Eruca sativa and Isatis tinctoria. Acyl derivatives of known GSLs comprised 15 of the 26 newly documented structures, while the remaining exhibited new substitution patterns or chain length, or contained a mercapto group or related thio-functionality. GSL identification methods are reviewed, and the importance of using authentic references and structure-sensitive detection methods such as MS and NMR is stressed, especially when species with relatively unknown chemistry are analyzed. An example of qualitative GSL analysis is presented with experimental details (group separation and HPLC of both intact and desulfated GSLs, detection and structure determination by UV, MS, NMR and susceptibility to myrosinase) with emphasis on the use of NMR for structure elucidation of even minor GSLs and GSL hydrolysis products. The example includes identification of a novel GSL, (R)-2-hydroxy-2-(3-hydroxyphenyl)ethylglucosinolate. Recent investigations of GSL evolution, based on investigations of species with well established phylogeny, are reviewed. From the relatively few such investigations, it is already clear that GSL profiles are regularly subject to evolution. This result is compatible with natural selection for specific GSL side chains. The probable existence of structure-specific GSL catabolism in intact plants suggests

  7. Gas evolution from spheres

    Science.gov (United States)

    Longhurst, G. R.

    1991-04-01

    Gas evolution from spherical solids or liquids where no convective processes are active is analyzed. Three problem classes are considered: (1) constant concentration boundary, (2) Henry's law (first order) boundary, and (3) Sieverts' law (second order) boundary. General expressions are derived for dimensionless times and transport parameters appropriate to each of the classes considered. However, in the second order case, the non-linearities of the problem require the presence of explicit dimensional variables in the solution. Sample problems are solved to illustrate the method.

  8. Evolution of atherectomy devices.

    Science.gov (United States)

    Al Khoury, G; Chaer, R

    2011-08-01

    Percutaneous atherectomy provides an alternative approach to the endovascular treatment of peripheral atherosclerotic occlusive disease beyond angioplasty and stenting, and has the theoretical advantage of lesion debulking and minimizing barotrauma to the vessel wall. Atherectomy has evolved greatly during the last decade, with currently four FDA approved devices for the treatment of peripheral arterial disease. Several reports have focused on the initial technical success rates, and demonstrated the safety and short as well as mid-term efficacy of atherectomy devices. This article will review the evolution of current atherectomy devices and the associated literature.

  9. Microphysics evolution and methodology

    International Nuclear Information System (INIS)

    Dionisio, J.S.

    1990-01-01

    A few general features of microscopics evolution and their relationship with microscopics methodology are briefly surveyed. Several pluri-disciplinary and interdisciplinary aspects of microscopics research are also discussed in the present scientific context. The need for an equilibrium between individual tendencies and collective constraints required by team work, already formulated thirty years ago by Frederic Joliot, is particularly stressed in the present conjuncture of Nuclear Research favouring very large team projects and discouraging individual initiatives. The increasing importance of the science of science (due to their multiple social, economical, ecological aspects) and the stronger competition between national and international tendencies of scientific (and technical) cooperation are also discussed. (author)

  10. Chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Pagel, B.E.J.

    1990-01-01

    Initial conditions are probably set by results of Big Bang nucleosynthesis (BBNS) without intervening complications affecting the composition of visible matter so that extrapolation of observed abundances to BBNS products seems fairly secure. Primordial helium and deuterium abundances deduced in this way place upper and lower limits on baryonic density implying that both baryonic and non-baryonic dark matter exist and predicting no more than 3 neutrino flavours as recently confirmed in accelerator experiments. The validity of simple galactic chemical evolution models assumed in extrapolating back to the Big Bang is examined in the light of the frequency distribution of iron or oxygen abundances in the Galactic halo, bulge and disk. (orig.)

  11. Electrochemical Hydrogen Evolution

    DEFF Research Database (Denmark)

    Laursen, A.B.; Varela Gasque, Ana Sofia; Dionigi, F.

    2012-01-01

    The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing new, inexpensive, and abundant HER catalysts is important. Here, we describe how a simple experiment...... catalysts based on this. Suited for upper-level high school and first-year university students, this exercise involves using a basic two-cell electrochemical setup to test multiple electrode materials as catalysts at one applied potential, and then constructing a volcano curve with the resulting currents...

  12. Nonlinear evolution equations

    CERN Document Server

    Uraltseva, N N

    1995-01-01

    This collection focuses on nonlinear problems in partial differential equations. Most of the papers are based on lectures presented at the seminar on partial differential equations and mathematical physics at St. Petersburg University. Among the topics explored are the existence and properties of solutions of various classes of nonlinear evolution equations, nonlinear imbedding theorems, bifurcations of solutions, and equations of mathematical physics (Navier-Stokes type equations and the nonlinear Schrödinger equation). The book will be useful to researchers and graduate students working in p

  13. A new evolution equation

    International Nuclear Information System (INIS)

    Laenen, E.

    1995-01-01

    We propose a new evolution equation for the gluon density relevant for the region of small x B . It generalizes the GLR equation and allows deeper penetration in dense parton systems than the GLR equation does. This generalization consists of taking shadowing effects more comprehensively into account by including multigluon correlations, and allowing for an arbitrary initial gluon distribution in a hadron. We solve the new equation for fixed α s . We find that the effects of multigluon correlations on the deep-inelastic structure function are small. (orig.)

  14. The evolution of galaxies at moderate redshift

    International Nuclear Information System (INIS)

    Lilly, S.J.

    1987-01-01

    Optical and infrared photometric data on 53 galaxies in five clusters at 0.38 < z < 0.58 are described and analysed to produce the rest-frame (U-V) and (V-H) colours. The 36 red galaxies form a homogeneous population in each cluster. The colours of the 17 blue galaxies clearly distinguish between the normal spirals and the peculiar 'A-type' galaxies found in these Butcher-Oemler clusters and suggest for the latter a substantial intermediate age 1-Gyr population as indicated by optical spectra. The average colours of the red elliptical galaxies at z ∼ 0.45 are systematically 0.12 mag bluer in the rest-frame (U-V), as expected from conventional evolutionary models, but are about 0.1 mag redder in (V-H), which is not predicted by the models. It is shown, however, that inclusion of the evolution of the upper Asymptotic Giant Branch, which is usually neglected, into a simple evolutionary model can explain the observed evolution vector in the (U-V)/(V-H) plane. (author)

  15. Papillomaviruses: Viral evolution, cancer and evolutionary medicine.

    Science.gov (United States)

    Bravo, Ignacio G; Félez-Sánchez, Marta

    2015-01-28

    Papillomaviruses (PVs) are a numerous family of small dsDNA viruses infecting virtually all mammals. PVs cause infections without triggering a strong immune response, and natural infection provides only limited protection against reinfection. Most PVs are part and parcel of the skin microbiota. In some cases, infections by certain PVs take diverse clinical presentations from highly productive self-limited warts to invasive cancers. We propose PVs as an excellent model system to study the evolutionary interactions between the immune system and pathogens causing chronic infections: genotypically, PVs are very diverse, with hundreds of different genotypes infecting skin and mucosa; phenotypically, they display extremely broad gradients and trade-offs between key phenotypic traits, namely productivity, immunogenicity, prevalence, oncogenicity and clinical presentation. Public health interventions have been launched to decrease the burden of PV-associated cancers, including massive vaccination against the most oncogenic human PVs, as well as systematic screening for PV chronic anogenital infections. Anti-PVs vaccines elicit protection against infection, induce cross-protection against closely related viruses and result in herd immunity. However, our knowledge on the ecological and intrapatient dynamics of PV infections remains fragmentary. We still need to understand how the novel anthropogenic selection pressures posed by vaccination and screening will affect viral circulation and epidemiology. We present here an overview of PV evolution and the connection between PV genotypes and the phenotypic, clinical manifestations of the diseases they cause. This differential link between viral evolution and the gradient cancer-warts-asymptomatic infections makes PVs a privileged playground for evolutionary medicine research. © The Author(s) 2015. Published by Oxford University Press on behalf of the Foundation for Evolution, Medicine, and Public Health.

  16. The early thermal evolution of Mars

    Science.gov (United States)

    Bhatia, G. K.; Sahijpal, S.

    2016-01-01

    Hf-W isotopic systematics of Martian meteorites have provided evidence for the early accretion and rapid core formation of Mars. We present the results of numerical simulations performed to study the early thermal evolution and planetary scale differentiation of Mars. The simulations are confined to the initial 50 Myr (Ma) of the formation of solar system. The accretion energy produced during the growth of Mars and the decay energy due to the short-lived radio-nuclides 26Al, 60Fe, and the long-lived nuclides, 40K, 235U, 238U, and 232Th are incorporated as the heat sources for the thermal evolution of Mars. During the core-mantle differentiation of Mars, the molten metallic blobs were numerically moved using Stoke's law toward the center with descent velocity that depends on the local acceleration due to gravity. Apart from the accretion and the radioactive heat energies, the gravitational energy produced during the differentiation of Mars and the associated heat transfer is also parametrically incorporated in the present work to make an assessment of its contribution to the early thermal evolution of Mars. We conclude that the accretion energy alone cannot produce widespread melting and differentiation of Mars even with an efficient consumption of the accretion energy. This makes 26Al the prime source for the heating and planetary scale differentiation of Mars. We demonstrate a rapid accretion and core-mantle differentiation of Mars within the initial ~1.5 Myr. This is consistent with the chronological records of Martian meteorites.

  17. Chemical evolution coefficients for the study of galactic evolution

    Energy Technology Data Exchange (ETDEWEB)

    Mallik, D C.V. [Indian Inst. of Astrophysics, Bangalore

    1980-05-01

    A new evaluation of chemical evolution coefficients has been made using recent stellar evolution and nucleosynthesis data. The role of the low and intermediate mass stars in galactic nucleosynthesis has been emphasized. A significant amount of /sup 4/He, /sup 12/C and neutron-rich species is found to be contributed by these stars. Comparison with observed abundances suggests a primary origin of /sup 14/N. The simple model of galactic evolution with the new coefficients has been used to derive the ratio of helium to heavy element enrichment in the Galaxy. The new stellar evolution data do not explain the large value of this ratio that has been determined observationally.

  18. Chemical evolution coefficients for the study of galactic evolution

    International Nuclear Information System (INIS)

    Mallik, D.C.V.

    1980-01-01

    A new evaluation of chemical evolution coefficients has been made using recent stellar evolution and nucleosynthesis data. The role of the low and intermediate mass stars in galactic nuclosynthesis has been emphasized. A significant amount of 4 He, 12 C and neutron-rich species is found to be contributed by these stars. Comparison with observed abundances suggests a primary origin of 14 N. The simple model of galactic evolution with the new coefficients has been used to derive the ratio of helium to heavy element enrichment in the Galaxy. The new stellar evolution data do not explain the large value of this ratio that has been determined observationally. (orig.)

  19. Concrete Chemical Evolution

    Energy Technology Data Exchange (ETDEWEB)

    D.H. Tang

    1998-07-31

    The objectives of this analysis are to discuss and evaluate testing results that were performed for the M&O by the Pennsylvania State University (PSU) to evaluate the potential long-term evolution of organic admixtures in cementitious materials at elevated temperatures. The testing was designed to help provide a basis for a determination by the Performance Assessment group (PA) of the long-term acceptability and longevity of cementitious materials for repository use. The main purpose of the testing was to assess the evolution of gases (especially CO{sub 2}) from hydrated cement paste at elevated temperatures and to determine the impact on alkalinity, i.e., the pH value of cement paste pore solution. This information in turn can be used as scoping information to determine if further tests of this nature are needed to support PA. As part of this discussion and evaluation of the PSU results, an assessment of alkalinity in a ''cementitious repository'' and an evaluation of organic materials are presented.

  20. The Evolution of Photosynthesis

    International Nuclear Information System (INIS)

    Broda, E.

    1976-01-01

    This Review was written by Engelbert Broda, an Austrian Chemist and Physicist, on February the 10th 1976. The merits of the inductive and the deductive approach in tracing the pathways of evolution are discussed. Using the latter approach, it is concluded that photosynthesis followed fermentation as a method of obtaining energy-rich compounds, especially ATP. Photosynthesis probably arose by utilization of membranes for bioenergetic processes. Originally photosynthesis served photophosphorylation (ATP production), later reducing power was also made, either by open-ended, light-powered, electron flow or driven by ATP; ultimate electron donors were at first hydrogen or sulfur compounds, and later water, the last-named capability Was acquired by prokaryotic algae the earliest plants, similar to the recent blue-greens. When free oxygen entered the atmosphere for the first time, various forms of respiration (oxidative phosphorylation) became possible. Mechanistically, respiration evolved from photosynthesis (‘conversion hypotheses’). Prokaryotic algae are probably the ancestors of the chloroplasts in the eukaryotes, In the evolution of the eukaryotes, not much change in the basic processes of photosynthesis occurred.(author)

  1. Concrete Chemical Evolution

    International Nuclear Information System (INIS)

    D.H. Tang

    1998-01-01

    The objectives of this analysis are to discuss and evaluate testing results that were performed for the M andO by the Pennsylvania State University (PSU) to evaluate the potential long-term evolution of organic admixtures in cementitious materials at elevated temperatures. The testing was designed to help provide a basis for a determination by the Performance Assessment group (PA) of the long-term acceptability and longevity of cementitious materials for repository use. The main purpose of the testing was to assess the evolution of gases (especially CO 2 ) from hydrated cement paste at elevated temperatures and to determine the impact on alkalinity, i.e., the pH value of cement paste pore solution. This information in turn can be used as scoping information to determine if further tests of this nature are needed to support PA. As part of this discussion and evaluation of the PSU results, an assessment of alkalinity in a ''cementitious repository'' and an evaluation of organic materials are presented

  2. Evolution of stellar systems

    International Nuclear Information System (INIS)

    Vader, P.

    1981-01-01

    The stellar systems of which the evolution will be considered in this thesis, are either galaxies, which contain about 10 11 stars, or binary systems, which consist of only two stars. It is seen that binary systems can give us some insight into the relative age of the nucleus of M31. The positive correlation between the metal content of a galaxy and its mass, first noted for elliptical galaxies, seems to be a general property of galaxies of all types. The observed increase of metallicity with galaxy mass is too large to be accounted for by differences in the evolutionary stage of galaxies. To explain the observed correlation it is proposed that a relatively larger proportion of massive stars is formed in more massive galaxies. The physical basis is that the formation of massive stars seems to be tied to the enhanced gas-dynamical activity in more massive galaxies. A specific aspect of the production of heavy elements by massive stars is investigated in some detail. In 1979 a cluster of 18 point X-ray sources within 400 pc of the centre of M31 was detected with the Einstein satellite. This is a remarkable result since no equivalent of this cluster has been observed in the nucleus of our own Galaxy, which otherwise is very similar to that of M31. An explanation for this phenomenon is proposed, suggesting that X-ray binaries are the products of the long-term evolution of nova systems. (Auth.)

  3. Evolution of Supernova Remnants

    Science.gov (United States)

    Arbutina, B.

    2017-12-01

    This book, both a monograph and a graduate textbook, is based on my original research and partly on the materials prepared earlier for the 2007 and 2008 IARS Astrophysics Summer School in Istanbul, AstroMundus course 'Supernovae and Their Remnants' that was held for the first time in 2011 at the Department of Astronomy, Faculty of Mathematics, University of Belgrade, and a graduate course 'Evolution of Supernova Remnants' that I teach at the aforementioned university. The first part Supernovae (introduction, thermonuclear supernovae, core-collapse supernovae) provides introductory information and explains the classification and physics of supernova explosions, while the second part Supernova remnants (introduction, shock waves, cosmic rays and particle acceleration, magnetic fields, synchrotron radiation, hydrodynamic and radio evolution of supernova remnants), which is the field I work in, is more detailed in scope i.e. technical/mathematical. Special attention is paid to details of mathematical derivations that often cannot be found in original works or available literature. Therefore, I believe it can be useful to both, graduate students and researchers interested in the field.

  4. Evolution of galaxies

    International Nuclear Information System (INIS)

    Palous, J.

    1987-01-01

    The proceedings contain 87 papers divided into 8 chapters. The chapter Bipolar outflows and star formations contains papers on optical and infrared observations of young bipolar outflow objects and the theory thereof, and on observations of cometary nebulae. The chapter Masers and early stellar evolution discusses molecular masers and star forming regions. The following chapter contains papers on initial mass function and star formation rates in galaxies. The chapter Clusters and star formation contains data on OB associations and open star clusters, their development and observations, CO and H 2 in our galaxy, the four vector model of radio emission and an atlas of the wavelength dependence of ultraviolet extinction in the Galaxy. The most voluminous is the chapter Evolution of galaxies. It contains papers on the theories of the physical and chemodynamic development of galaxies of different types, rotation research and rotation velocities of galaxies and their arms, and on mathematical and laboratory models of morphological development. Chapter seven contains papers dealing with active extragalactic objects, quasars and active galactic nuclei. The last chapter discusses cosmological models, the theory of the inflationary universe, and presents an interpretation of the central void and X-ray background. (M.D.). 299 figs., 48 tabs., 1651 refs

  5. Ultrastructure, macromolecules, and evolution

    CERN Document Server

    Dillon, Lawrence S

    1981-01-01

    Thus far in the history of biology, two, and only two, fundamental principles have come to light that pervade and unify the entire science-the cell theory and the concept of evolution. While it is true that recently opened fields of inves­ tigation have given rise to several generalizations of wide impact, such as the universality of DNA and the energetic dynamics of ecology, closer inspection reveals them to be part and parcel of either of the first two mentioned. Because in the final analysis energy can act upon an organism solely at the cellular level, its effects may be perceived basically to represent one facet of cell me­ tabolism. Similarly, because the DNA theory centers upon the means by which cells build proteins and reproduce themselves, it too proves to be only one more, even though an exciting, aspect of the cell theory. In fact, if the matter is given closer scrutiny, evolution itself can be viewed as being a fundamental portion of the cell concept, for its effects arise only as a consequence ...

  6. Modeling Protein Evolution

    Science.gov (United States)

    Goldstein, Richard; Pollock, David

    The study of biology is fundamentally different from many other scientific pursuits, such as geology or astrophysics. This difference stems from the ubiquitous questions that arise about function and purpose. These are questions concerning why biological objects operate the way they do: what is the function of a polymerase? What is the role of the immune system? No one, aside from the most dedicated anthropist or interventionist theist, would attempt to determine the purpose of the earth's mantle or the function of a binary star. Among the sciences, it is only biology in which the details of what an object does can be said to be part of the reason for its existence. This is because the process of evolution is capable of improving an object to better carry out a function; that is, it adapts an object within the constraints of mechanics and history (i.e., what has come before). Thus, the ultimate basis of these biological questions is the process of evolution; generally, the function of an enzyme, cell type, organ, system, or trait is the thing that it does that contributes to the fitness (i.e., reproductive success) of the organism of which it is a part or characteristic. Our investigations cannot escape the simple fact that all things in biology (including ourselves) are, ultimately, the result of an evolutionary process.

  7. Chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Pagel, B.E.J.

    1979-01-01

    The chemical evolution of disk galaxies is discussed with special reference to results obtained from studies of the oxygen abundance in H II regions. Normal spirals (including our own) display the by now well known radial abundance gradient, which is discussed on the basis of the simple enrichment model and other models. The Magellanic Clouds, on the other hand, and the barred spiral NGC 1365, have been found to have little or no abundance gradient, implying a very different sort of evolution that may involve large-scale mixing. Finally, the simple model is tested against a number of results in H II regions where the ratio of total mass to mass of residual gas can be estimated. It turns out to fit adequately the Magellanic Clouds and a number of H II regions in the outer parts of spiral galaxies, but in more inner parts it fails, as do more sophisticated models involving infall during the formation of galactic disks that have proved very successful in other respects. (Auth.)

  8. Stellar Structure and Evolution

    CERN Document Server

    Kippenhahn, Rudolf; Weiss, Achim

    2013-01-01

    This long-awaited second edition of the classical textbook on Stellar Structure and Evolution by Kippenhahn and Weigert is a thoroughly revised version of the original text. Taking into account modern observational constraints as well as additional physical effects such as mass loss and diffusion, Achim Weiss and Rudolf Kippenhahn have succeeded in bringing the book up to the state-of-the-art with respect to both the presentation of stellar physics and the presentation and interpretation of current sophisticated stellar models. The well-received and proven pedagogical approach of the first edition has been retained. The book provides a comprehensive treatment of the physics of the stellar interior and the underlying fundamental processes and parameters. The models developed to explain the stability, dynamics and evolution of the stars are presented and great care is taken to detail the various stages in a star’s life. Just as the first edition, which remained a standard work for more than 20 years after its...

  9. Evolution across the Curriculum: Microbiology

    Directory of Open Access Journals (Sweden)

    Alita R. Burmeister

    2016-05-01

    Full Text Available An integrated understanding of microbiology and evolutionary biology is essential for students pursuing careers in microbiology and healthcare fields. In this Perspective, we discuss the usefulness of evolutionary concepts and an overall evolutionary framework for students enrolled in microbiology courses. Further, we propose a set of learning goals for students studying microbial evolution concepts. We then describe some barriers to microbial evolution teaching and learning and encourage the continued incorporation of evidence-based teaching practices into microbiology courses at all levels. Next, we review the current status of microbial evolution assessment tools and describe some education resources available for teaching microbial evolution. Successful microbial evolution education will require that evolution be taught across the undergraduate biology curriculum, with a continued focus on applications and applied careers, while aligning with national biology education reform initiatives.

  10. Evolution across the Curriculum: Microbiology

    Science.gov (United States)

    Burmeister, Alita R.; Smith, James J.

    2016-01-01

    An integrated understanding of microbiology and evolutionary biology is essential for students pursuing careers in microbiology and healthcare fields. In this Perspective, we discuss the usefulness of evolutionary concepts and an overall evolutionary framework for students enrolled in microbiology courses. Further, we propose a set of learning goals for students studying microbial evolution concepts. We then describe some barriers to microbial evolution teaching and learning and encourage the continued incorporation of evidence-based teaching practices into microbiology courses at all levels. Next, we review the current status of microbial evolution assessment tools and describe some education resources available for teaching microbial evolution. Successful microbial evolution education will require that evolution be taught across the undergraduate biology curriculum, with a continued focus on applications and applied careers, while aligning with national biology education reform initiatives. Journal of Microbiology & Biology Education PMID:27158306

  11. Effects of conformism on the cultural evolution of social behaviour.

    Directory of Open Access Journals (Sweden)

    Lucas Molleman

    Full Text Available Models of cultural evolution study how the distribution of cultural traits changes over time. The dynamics of cultural evolution strongly depends on the way these traits are transmitted between individuals by social learning. Two prominent forms of social learning are payoff-based learning (imitating others that have higher payoffs and conformist learning (imitating locally common behaviours. How payoff-based and conformist learning affect the cultural evolution of cooperation is currently a matter of lively debate, but few studies systematically analyse the interplay of these forms of social learning. Here we perform such a study by investigating how the interaction of payoff-based and conformist learning affects the outcome of cultural evolution in three social contexts. First, we develop a simple argument that provides insights into how the outcome of cultural evolution will change when more and more conformist learning is added to payoff-based learning. In a social dilemma (e.g. a Prisoner's Dilemma, conformism can turn cooperation into a stable equilibrium; in an evasion game (e.g. a Hawk-Dove game or a Snowdrift game conformism tends to destabilize the polymorphic equilibrium; and in a coordination game (e.g. a Stag Hunt game, conformism changes the basin of attraction of the two equilibria. Second, we analyse a stochastic event-based model, revealing that conformism increases the speed of cultural evolution towards pure equilibria. Individual-based simulations as well as the analysis of the diffusion approximation of the stochastic model by and large confirm our findings. Third, we investigate the effect of an increasing degree of conformism on cultural group selection in a group-structured population. We conclude that, in contrast to statements in the literature, conformism hinders rather than promotes the evolution of cooperation.

  12. Effects of conformism on the cultural evolution of social behaviour.

    Science.gov (United States)

    Molleman, Lucas; Pen, Ido; Weissing, Franz J

    2013-01-01

    Models of cultural evolution study how the distribution of cultural traits changes over time. The dynamics of cultural evolution strongly depends on the way these traits are transmitted between individuals by social learning. Two prominent forms of social learning are payoff-based learning (imitating others that have higher payoffs) and conformist learning (imitating locally common behaviours). How payoff-based and conformist learning affect the cultural evolution of cooperation is currently a matter of lively debate, but few studies systematically analyse the interplay of these forms of social learning. Here we perform such a study by investigating how the interaction of payoff-based and conformist learning affects the outcome of cultural evolution in three social contexts. First, we develop a simple argument that provides insights into how the outcome of cultural evolution will change when more and more conformist learning is added to payoff-based learning. In a social dilemma (e.g. a Prisoner's Dilemma), conformism can turn cooperation into a stable equilibrium; in an evasion game (e.g. a Hawk-Dove game or a Snowdrift game) conformism tends to destabilize the polymorphic equilibrium; and in a coordination game (e.g. a Stag Hunt game), conformism changes the basin of attraction of the two equilibria. Second, we analyse a stochastic event-based model, revealing that conformism increases the speed of cultural evolution towards pure equilibria. Individual-based simulations as well as the analysis of the diffusion approximation of the stochastic model by and large confirm our findings. Third, we investigate the effect of an increasing degree of conformism on cultural group selection in a group-structured population. We conclude that, in contrast to statements in the literature, conformism hinders rather than promotes the evolution of cooperation.

  13. The evolution of Lean organizations

    OpenAIRE

    Serafinas, Dalius; Ruželė, Darius

    2014-01-01

    Remiantis evoliucijos tyrimų modeliais bei autorių sudarytu evoliucionuojančios organizacijos modeliu,straipsnyje analizuojama Lean vadybos metodologija ir tiriama, kaip evoliucionuoja ją įgyvendinančios Lietuvosgamybinės organizacijos. The purpose of this paper is to examine the evolution of Lean organizations.Design/methodology/approach: a conceptual literature on the evolution of species, organisms and organizations was reviewed and an original model (framework) of the evolution of orga...

  14. Tracing Cultural Evolution Through Memetics

    OpenAIRE

    Tiktik Dewi Sartika

    2004-01-01

    Viewing human being, as a part of evolution process is still a controversial issue for some people, in fact the evolution runs. As a sociocultural entity, human being has distinctive characters in its evolution process. A Theory inherited from Darwin may have only been able to answer how a simple unit such genes evolve to such complex animal like human. Yet, how among those complex animals interact, communicate, and replicate idea in so forth formed a such self-organized sociocultural complex...

  15. Use of the "Tree" Analogy in Evolution Teaching by Biology Teachers

    Science.gov (United States)

    Marcelos, Maria Fatima; Nagem, Ronaldo Luiz

    2012-01-01

    This work discusses the use of Darwin's "Tree of Life" as a didactic analogy and metaphor in teaching evolution. It investigates whether biology teachers of pupils from 17 to 18 years old know Darwin's text "Tree of Life". In addition, it examines whether those teachers systematically employ either the analogies present in that…

  16. Comparing the evolution of national research policies: what patterns of change?

    NARCIS (Netherlands)

    Lepori, Benedetto; van den Besselaar, Peter; Dinges, Michael; Poti, Bianca; Reale, Emanuela; Slipersaeter, Stig; Theves, Jean; van der Meulen, Barend

    2007-01-01

    This article presents a comparative analysis of the evolution of national research policies during the past three decades in six European countries (Austria, Italy, France, Netherlands, Norway and Switzerland), with a special focus on the changes of public project funding schemes. It systematically

  17. Systematic literature review

    DEFF Research Database (Denmark)

    Barnard, K. D.; Lloyd, C. E.; Skinner, T. C.

    2007-01-01

    mixed results, with one study reporting quality of life benefits and one reporting no evidence of quality of life benefits. Conclusions: There is conflicting evidence reported in the various studies on the quality of life benefits of CSII in Type 1 diabetes. Existing research is flawed, making......Aim: To review systematically the published literature addressing whether continuous subcutaneous insulin infusion (CSII) provides any quality of life benefits to people with Type 1 diabetes. Methods: Electronic databases and published references were searched and a consultation with two...

  18. Systematic Equation Formulation

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2007-01-01

    A tutorial giving a very simple introduction to the set-up of the equations used as a model for an electrical/electronic circuit. The aim is to find a method which is as simple and general as possible with respect to implementation in a computer program. The “Modified Nodal Approach”, MNA, and th......, and the “Controlled Source Approach”, CSA, for systematic equation formulation are investigated. It is suggested that the kernel of the P Spice program based on MNA is reprogrammed....

  19. Evolution of Vision

    Science.gov (United States)

    Ostrovsky, Mikhail

    The evolution of photoreception, giving rise to eye, offers a kaleidoscopic view on selection acting at both the organ and molecular levels. The molecular level is mainly considered in the lecture. The greatest progress to date has been made in relation to the opsin visual pigments. Opsins appeared before eyes did. Two- and three-dimensional organization for rhodopsin in the rod outer segment disk membrane, as well as molecular mechanisms of visual pigments spectral tuning, photoisomerization and also opsin as a G-protein coupled receptor are considered. Molecular mechanisms of visual pigments spectral tuning, namely switching of chromophore (physiological time scale) and amino acid changes in the chromophore site of opsin (evolutionary time scale) is considered in the lecture. Photoisomerization of rhodopsin chromophore, 11-cis retinal is the only photochemical reaction in vision. The reaction is extemely fast (less that 200 fs) and high efficient (. is 0.65). The rhodopsin photolysis and kinetics of the earlier products appearance, photo- and bathorhodopsin, is considered. It is known that light is not only a carrier of information, but also a risk factor of damage to the eye. This photobiological paradox of vision is mainly due to the nature of rhodopsin chromophore. Photooxidation is the base of the paradox. All factors present in the phototrceptor cells to initiate free-radical photooxidation: photosensitizers, oxygen and substrates of oxidation: lipids and proteins (opsin). That is why photoprotective system of the eye structures appeared in the course of evolution. Three lines of protective system to prevent light damage to the retina and retina pigment epithelium is known: permanent renewal of rod and cone outer segment, powerful antioxidant system and optical media as cut-off filters where the lens is a key component. The molecular mechanisms of light damage to the eye and photoprotective system of the eye is considered in the lecture. The molecular

  20. MNE R&D Subsidiary Mandates Evolution in Emerging Economies

    DEFF Research Database (Denmark)

    Schulzmann, David; Slepniov, Dmitrij

    2017-01-01

    The aim of this paper is to present the results of a systematic literature review (SLR) on the subject of Research and Development (R&D) subsidiary mandate evolution in emerging economies and to illustrate what triggers R&D mandate upgrade. The subject of R&D mandates is of crucial importance to ...... on subsidiary evolution in general and particularly in emerging markets. From a practical perspective, a better-integrated framework can provide guidance to businesses in emerging economies on how to start and successfully upgrade their R&D activities.......The aim of this paper is to present the results of a systematic literature review (SLR) on the subject of Research and Development (R&D) subsidiary mandate evolution in emerging economies and to illustrate what triggers R&D mandate upgrade. The subject of R&D mandates is of crucial importance...... to many multinational enterprises (MNEs) striving to utilize the potential of their foreign operations towards higher-value-added activities. While developed economies have long been a destination for R&D activities, emerging economies are increasingly recognized for their innovation potential. Previous...

  1. Micro-droplet based directed evolution outperforms conventional laboratory evolution

    DEFF Research Database (Denmark)

    Sjostrom, Staffan L.; Huang, Mingtao; Nielsen, Jens

    2014-01-01

    We present droplet adaptive laboratory evolution (DrALE), a directed evolution method used to improve industrial enzyme producing microorganisms for e.g. feedstock digestion. DrALE is based linking a desired phenotype to growth rate allowing only desired cells to proliferate. Single cells are con...... a whole-genome mutated library of yeast cells for α-amylase activity....

  2. Evolution of Modularity Literature

    DEFF Research Database (Denmark)

    Frandsen, Thomas

    2017-01-01

    Purpose The purpose of this paper is to review and analyze the modularity literature to identify the established and emerging perspectives. Design/methodology/approach A systematic literature search and review was conducted through the use of bibliometrics and network analysis. The analysis...... identified structure within the literature, which revealed how the research area evolved between 1990 and 2015. Based on this search, the paper establishes the basis for analyzing the structure of modularity literature. Findings Factors were identified within the literature, demonstrating how it has evolved...... from a primary focus on the modularity of products to a broader view of the applicability of modularity. Within the last decade, numerous research areas have emerged within the broader area of modularity. Through core-periphery analysis, eight emerging sub-research areas are identified, of which one...

  3. Evolution of knowledge management

    Directory of Open Access Journals (Sweden)

    Mašić Branislav

    2017-01-01

    Full Text Available The theory of business and management is changing rapidly, and changes are expected to continue. Emerging concepts and paradigms are being introduced and applied to organizational life. Knowledge management (KM is not new but rather newly structured concept. Although the concept was not popularized until the last two decades of the 20th century, transmitting and managing knowledge stretch back into distant history. The aim of this paper is to analyse knowledge management evolutionary history and to investigate the use of knowledge management as management tool in organizations. This paper is focused on systematic review of literature on knowledge management. Emphasis is placed on correlation between knowledge management and information and communication technology and advent and use of new tools and techniques; change in the way knowledge has been conceptualized; social context of KM, big data and analytics, artificial intelligence. The importance of knowledge itself was not questioned, as it is recognized as highly valuable resource.

  4. Evolution of filament barbs.

    Science.gov (United States)

    Liu, R.; Xu, Y.; Wang, H.

    We present a selected few cases in which the sense of chirality of filament barbs changed within periods as short as hours. We investigate in detail a quiescent filament on 2003 September 10 and 11. Of its four barbs displaying such changes, only one overlays a small polarity inversion line inside the EUV filament channel (EFC). No magnetic elements with magnitude above the noise level were detected at the endpoints of all barbs. In particular, a pair of barbs first approached toward, and then departed from, each other in Halpha , with the barb endpoints migrating as far as ˜ 10 arcsec. We conclude that the evolution of the barbs was driven by flux emergence and cancellation of small bipolar units at the EFC border.

  5. ABWR evolution program

    International Nuclear Information System (INIS)

    Omoto, A.; Tanabe, A.; Moriya, K.; Dillmann, C.W.

    1993-01-01

    The ABWR plant is becoming a commercial reality in Japan where the first two units are being built by the Tokyo Electric Power Company. Although these units are scheduled to come on line in 1996 and '97, the Tokyo Electric Power Company, jointly with NSSS vendors (General Electric, Toshiba and Hitachi) and Japanese BWR utilities, initiated a program for a new plant design. This program is aimed at the further evolution of the ABWR to take advantage of new technological developments and to meet possible social changes in the years to come. The expected time for the first-of-a-kind plant to come on line is in the 2010's when the first generation plants in Japan may approach the time for replacement. This paper presents the ouline of this program with focus on the utility requirements and candidate technologies. (orig.)

  6. Evolution of dwarf binaries

    International Nuclear Information System (INIS)

    Tutukov, A.V.; Fedorova, A.V.; Yungel'son, L.R.

    1982-01-01

    The conditions of mass exchange in close binary systems with masses of components less or equal to one solar mass have been analysed for the case, when the system radiates gravitational waves. It has been shown that the mass exchange rate depends in a certain way on the mass ratio of components and on the mass of component that fills its inner critical lobe. The comparison of observed periods, masses of contact components, and mass exchange rates of observed cataclysmic binaries have led to the conclusion that the evolution of close binaries WZ Sge, OY Car, Z Cha, TT Ari, 2A 0311-227, and G 61-29 may be driven by the emission of gravitational waves [ru

  7. Evolution of paradigms

    International Nuclear Information System (INIS)

    Reuss, P.

    1997-01-01

    The evolution of the concepts and methods used for describing neutronics through the last thirty years is reviewed, with the important role attributed to computer technology and the capacity to perform more precise calculations and models; the various codes such as HETAIRE and APOLLO, used for the Boltzmann equation, are discussed, together with the calculation methods and theories that gain interest or those which were more or less discarded depending on the modelling capacities and nuclear industry choices. The role of experimentations is still essential for neutronics, in order to supply data when theory or data are limited or to validate models and codes. Trends are with structured and modular codes integrating all the know-how of a domain and with increased cooperation with other sectors such as thermohydraulics, thermomechanics, etc

  8. Lossless conditional schema evolution

    DEFF Research Database (Denmark)

    Jensen, Ole Guttorm; Böhlen, Michael

    2004-01-01

    is a precondition for a flexible semantics that allows to correctly answer general queries over evolving schemas. The key challenge is to handle attribute mismatches between the intended and recorded schema in a consistent way. We provide a parametric approach to resolve mismatches according to the needs......Conditional schema changes change the schema of the tuples that satisfy the change condition. When the schema of a relation changes some tuples may no longer fit the current schema. Handling the mismatch between the intended schema of tuples and the recorded schema of tuples is at the core...... of a DBMS that supports schema evolution. We propose to keep track of schema mismatches at the level of individual tuples, and prove that evolving schemas with conditional schema changes, in contrast to database systems relying on data migration, are lossless when the schema evolves. The lossless property...

  9. Explaining Poverty Evolution

    DEFF Research Database (Denmark)

    Arndt, Channing; Hussain, Mohammad Azhar; Jones, Edward Samuel

    Measuring poverty remains a complex and contentious issue. This is particularly true in sub-Saharan Africa where poverty rates are higher, information bases typically weaker, and the underlying determinants of welfare relatively volatile. This paper employs recently collected data on household...... consumption in Mozambique to examine the evolution of consumption poverty with focus on the period 2002/03 to 2008/09. The paper contributes in four areas. First, the period in question was characterized by major movements in international commodity prices. Mozambique provides an illuminating case study...... of the implications of these world commodity price changes for living standards of poor people. Second, a novel ‘backcasting’ approach using a computable general equilibrium model of Mozambique, linked to a poverty module is introduced. Third, the backcasting approach is also employed to rigorously examine...

  10. Spectral evolution of galaxies

    International Nuclear Information System (INIS)

    Rocca-Volmerange, B.

    1989-01-01

    A recent striking event in Observational Cosmology is the discovery of a large population of galaxies at extreme cosmological distances (extended from spectral redshifts ≅ 1 to ≥ 3) corresponding to a lookback time of 80% of the Universe's age. However when galaxies are observed at such remote epochs, their appearances are affected by at least two simultaneous effects which are respectively a cosmological effect and the intrinsic evolution of their stellar populations which appear younger than in our nearby galaxies. The fundamental problem is first to disentangle the respective contributions of these two effects to apparent magnitudes and colors of distant galaxies. Other effects which are likely to modify the appearance of galaxies are amplification by gravitational lensing and interaction with environment will also be considered. (author)

  11. Manufacturing network evolution

    DEFF Research Database (Denmark)

    Yang, Cheng; Farooq, Sami; Johansen, John

    2011-01-01

    Purpose – This paper examines the effect of changes at the manufacturing plant level on other plants in the manufacturing network and also investigates the role of manufacturing plants on the evolution of a manufacturing network. Design/methodology/approach –The research questions are developed...... different manufacturing plants in the network and their impact on network transformation. Findings – The paper highlights the dominant role of manufacturing plants in the continuously changing shape of a manufacturing network. The paper demonstrates that a product or process change at one manufacturing...... by identifying the gaps in the reviewed literature. The paper is based on three case studies undertaken in Danish manufacturing companies to explore in detail their manufacturing plants and networks. The cases provide a sound basis for developing the research questions and explaining the interaction between...

  12. Monitoring Evolution at CERN

    CERN Document Server

    Andrade, P; Murphy, S; Pigueiras, L; Santos, M

    2015-01-01

    Over the past two years, the operation of the CERN Data Centres went through significant changes with the introduction of new mechanisms for hardware procurement, new services for cloud provisioning and configuration management, among other improvements. These changes resulted in an increase of resources being operated in a more dynamic environment. Today, the CERN Data Centres provide over 11000 multi-core processor servers, 130 PB disk servers, 100 PB tape robots, and 150 high performance tape drives. To cope with these developments, an evolution of the data centre monitoring tools was also required. This modernisation was based on a number of guiding rules: sustain the increase of resources, adapt to the new dynamic nature of the data centres, make monitoring data easier to share, give more flexibility to Service Managers on how they publish and consume monitoring metrics and logs, establish a common repository of monitoring data, optimise the handling of monitoring notifications, and replace the previous ...

  13. Evolution of Flat Roofs

    Directory of Open Access Journals (Sweden)

    Şt. Vasiliu

    2009-01-01

    Full Text Available Roofs are constructive subassembles that are located at the top of buildings, which toghether with perimetral walls and some elements of the infrastructure belongs to the subsystem elements that close the building. Roofs must meet resistance requirements to mechanical action, thermal insulating, waterproofing and acoustic, fire resistance, durability, economy and aesthetics. The man saw the need to build roofs from the oldest ancient times. Even if the design of buildings has an empirical character, are known and are preserved until today constructions that are made in antiquity, by the Egyptians, Greeks and Romans with architectural achievements, worthy of admiration and in present time. General composition of civil construction has been influenced throughout the evolution of construction history by the level of production forces and properties of building materials available in every historical epoch. For over five millennia, building materials were stone, wood and ceramic products (concrete was used by theRomans only as filling material.

  14. Allergy in evolution.

    Science.gov (United States)

    Platts-Mills, Thomas A E

    2012-01-01

    The 'foreignness' of proteins that we encounter in our homes and outdoors is in large part dependent on their evolutionary distance from man. This is relevant to understanding the differences between mammalian allergens, e.g. cats, and arthropod allergens, e.g. mites and cockroaches, as well as to understanding responses to a wide range of food allergens. On the other hand, allergic disease has gone through a major evolution of its own from a prehygiene state where there is minimal production of allergen-specific IgE, to the production of high-titer IgE, and then to the dramatic increase in asthma. The challenge is to understand how changes in both hygiene and lifestyle have contributed to the changes in allergic disease. Copyright © 2012 S. Karger AG, Basel.

  15. The evolution of 'bricolage'.

    Science.gov (United States)

    Duboule, D; Wilkins, A S

    1998-02-01

    The past ten years of developmental genetics have revealed that most of our genes are shared by other species throughout the animal kingdom. Consequently, animal diversity might largely rely on the differential use of the same components, either at the individual level through divergent functional recruitment, or at a more integrated level, through their participation in various genetic networks. Here, we argue that this inevitably leads to an increase in the interdependency between functions that, in turn, influences the degree to which novel variations can be tolerated. In this 'transitionist' scheme, evolution is neither inherently gradualist nor punctuated but, instead, progresses from one extreme to the other, together with the increased complexity of organisms.

  16. Evolution of variable stars

    International Nuclear Information System (INIS)

    Becker, S.A.

    1986-08-01

    Throughout the domain of the H R diagram lie groupings of stars whose luminosity varies with time. These variable stars can be classified based on their observed properties into distinct types such as β Cephei stars, δ Cephei stars, and Miras, as well as many other categories. The underlying mechanism for the variability is generally felt to be due to four different causes: geometric effects, rotation, eruptive processes, and pulsation. In this review the focus will be on pulsation variables and how the theory of stellar evolution can be used to explain how the various regions of variability on the H R diagram are populated. To this end a generalized discussion of the evolutionary behavior of a massive star, an intermediate mass star, and a low mass star will be presented. 19 refs., 1 fig., 1 tab

  17. Gynecomastia: A systematic review.

    Science.gov (United States)

    Fagerlund, Anders; Lewin, Richard; Rufolo, Guglielmo; Elander, Anna; Santanelli di Pompeo, Fabio; Selvaggi, Gennaro

    2015-01-01

    Gynecomastia is a common medical problem presenting in nearly a third of the male population. Treatment for gynecomastia can be either pharmacological or surgical. Patients with gynecomastia often experience affected quality-of-life. The aim of this systematic review was to analyze the quality of evidence of the current literature in relation to different treatment modalities and Quality-of-Life in patients with gynecomastia. A systematic search of the literature was performed in PubMed, Medline, Scopus, The Cochrane Library, and SveMed+ in accordance with the PRISMA statement. All searches were undertaken between September-November 2014. The PICOS (patients, intervention, comparator, outcomes, and study design) approach was used to specify inclusion criteria. Methodological quality was graded according to MINORS. Quality of evidence was rated according to GRADE. Data from the included studies were extracted based on study characteristics, participants specifics, type of intervention/treatment, and type of outcome measures into data extraction forms. A total of 134 abstracts were identified in the literature search. Seventeen studies met inclusion criteria, 14 concerning treatment and three concerning Quality-of-Life. All studies were non-randomised with a high risk of bias and very low quality of evidence according to GRADE. Several different surgical methods have been described with good results, minimal scars, and various levels of complications. Traditional surgical excision of glandular tissue combined with liposuction provides most consistent results and a low rate of complications. Pubertal gynecomastia may safely be managed by pharmacological anti-oestrogen treatment.

  18. Telerheumatology: A Systematic Review.

    Science.gov (United States)

    McDougall, John A; Ferucci, Elizabeth D; Glover, Janis; Fraenkel, Liana

    2017-10-01

    To identify and summarize the published and gray literature on the use of telemedicine for the diagnosis and management of inflammatory and/or autoimmune rheumatic disease. We performed a registered systematic search (CRD42015025382) for studies using MEDLINE (1946 to July 2015), Embase (1974 to July 2015), Web of Science (1900 to July 2015), and Scopus (1946 to July 2015) databases. We included studies that demonstrated the use of telemedicine for diagnosis and/or management of inflammatory/autoimmune rheumatic disease. Following data extraction, we performed a descriptive analysis. Our literature search identified 1,468 potentially eligible studies. Of these studies, 20 were ultimately included in this review. Studies varied significantly in publication type, quality of evidence, and the reporting of methods. Most demonstrated a high risk of bias. Rheumatoid arthritis was the most commonly studied rheumatic disease (42% of patients). Studies demonstrated conflicting results regarding the effectiveness of telemedicine (18 found it effective, 1 found it effective but possibly harmful, and 1 found it ineffective). A limited number of studies included some component of a cost analysis (n = 6; 16% of patients); all of these found telemedicine to be cost-effective. Studies identified by this systematic review generally found telemedicine to be effective for the diagnosis and management of autoimmune/inflammatory rheumatic disease; however, there is limited evidence to support this conclusion. Further studies are needed to determine the best uses of telemedicine for the diagnosis and management of these conditions. © 2016, American College of Rheumatology.

  19. Evolution of the TOR Pathway.

    NARCIS (Netherlands)

    Dam, T.J.P. van; Zwartkruis, F.J.; Bos, J.L.; Snel, B.

    2011-01-01

    The TOR kinase is a major regulator of growth in eukaryotes. Many components of the TOR pathway are implicated in cancer and metabolic diseases in humans. Analysis of the evolution of TOR and its pathway may provide fundamental insight into the evolution of growth regulation in eukaryotes and

  20. Mammal Evolution, an mustrated Guide

    African Journals Online (AJOL)

    Mammal Evolution, an mustrated Guide. R.J.G. Savage and M.R. Long. British Museum of Natural ... structural anatomy of fossils can be related to their probable function. The body of the text discusses the ... gnawers, rooters and browsers, mammals on island continents, hoofed herbivores and ftnally primate evolution,.

  1. Nonlinear evolution of MHD instabilities

    International Nuclear Information System (INIS)

    Bateman, G.; Hicks, H.R.; Wooten, J.W.; Dory, R.A.

    1975-01-01

    A 3-D nonlinear MHD computer code was used to study the time evolution of internal instabilities. Velocity vortex cells are observed to persist into the nonlinear evolution. Pressure and density profiles convect around these cells for a weak localized instability, or convect into the wall for a strong instability. (U.S.)

  2. Systematic Software Development

    DEFF Research Database (Denmark)

    Kuhrmann, Marco; Méndez Fernández, Daniel

    2015-01-01

    The speed of innovation and the global allocation of resources to accelerate development or to reduce cost put pressure on the software industry. In the global competition, especially so-called high-price countries have to present arguments why the higher development cost is justified and what...... makes these countries an attractive host for software companies. Often, high-quality engineering and excellent quality of products, e.g., machinery and equipment, are mentioned. Yet, the question is: Can such arguments be also found for the software industry? We aim at investigating the degree...... of professionalism and systematization of software development to draw a map of strengths and weaknesses. To this end, we conducted as a first step an exploratory survey in Germany, presented in this paper. In this survey, we focused on the perceived importance of the two general software engineering process areas...

  3. Iridology: A systematic review.

    Science.gov (United States)

    Ernst, E

    1999-02-01

    Iridologists claim to be able to diagnose medical conditions through abnormalities of pigmentation in the iris. This technique is popular in many countries. Therefore it is relevant to ask whether it is valid. To systematically review all interpretable tests of the validity of iridology as a diagnostic tool. DATA SOURCE AND EXTRACTION: Three independent literature searches were performed to identify all blinded tests. Data were extracted in a predefined, standardized fashion. Four case control studies were found. The majority of these investigations suggests that iridology is not a valid diagnostic method. The validity of iridology as a diagnostic tool is not supported by scientific evaluations. Patients and therapists should be discouraged from using this method.

  4. Evolution of the Insects

    Science.gov (United States)

    Grimaldi, David; Engel, Michael S.

    2005-05-01

    This book chronicles the complete evolutionary history of insects--their living diversity and relationships as well as 400 million years of fossils. Introductory sections cover the living species diversity of insects, methods of reconstructing evolutionary relationships, basic insect structure, and the diverse modes of insect fossilization and major fossil deposits. Major sections then explore the relationships and evolution of each order of hexapods. The volume also chronicles major episodes in the evolutionary history of insects from their modest beginnings in the Devonian and the origin of wings hundreds of millions of years before pterosaurs and birds to the impact of mass extinctions and the explosive radiation of angiosperms on insects, and how they evolved into the most complex societies in nature. Whereas other volumes focus on either living species or fossils, this is the first comprehensive synthesis of all aspects of insect evolution. Illustrated with 955 photo- and electron- micrographs, drawings, diagrams, and field photos, many in full color and virtually all of them original, this reference will appeal to anyone engaged with insect diversity--professional entomologists and students, insect and fossil collectors, and naturalists. David Grimaldi and Michael S. Engel have collectively published over 200 scientific articles and monographs on the relationships and fossil record of insects, including 10 articles in the journals Science, Nature, and Proceedings of the National Academy of Sciences. David Grimaldi is curator in the Division of Invertebrate Zoology, American Museum of Natural History and adjunct professor at Cornell University, Columbia University, and the City University of New York. David Grimaldi has traveled in 40 countries on 6 continents, collecting and studying recent species of insects and conducting fossil excavations. He is the author of Amber: Window to the Past (Abrams, 2003). Michael S. Engel is an assistant professor in the

  5. Lakes, Lagerstaetten, and Evolution

    Science.gov (United States)

    Kordesch, E. G.; Park, L. E.

    2001-12-01

    nonmarine organisms, and thus the evolution of freshwater organisms, can occur in a short geologic timespan. Because of their unique and varied conditions, the evolution of nonmarine organisms may be linked to lake basin type as well as lake longevity.

  6. [Evolution of genomic imprinting in mammals: what a zoo!].

    Science.gov (United States)

    Proudhon, Charlotte; Bourc'his, Déborah

    2010-05-01

    Genomic imprinting imposes an obligate mode of biparental reproduction in mammals. This phenomenon results from the monoparental expression of a subset of genes. This specific gene regulation mechanism affects viviparous mammals, especially eutherians, but also marsupials to a lesser extent. Oviparous mammals, or monotremes, do not seem to demonstrate monoparental allele expression. This phylogenic confinement suggests that the evolution of the placenta imposed a selective pressure for the emergence of genomic imprinting. This physiological argument is now complemented by recent genomic evidence facilitated by the sequencing of the platypus genome, a rare modern day case of a monotreme. Analysis of the platypus genome in comparison to eutherian genomes shows a chronological and functional coincidence between the appearance of genomic imprinting and transposable element accumulation. The systematic comparative analyses of genomic sequences in different species is essential for the further understanding of genomic imprinting emergence and divergent evolution along mammalian speciation.

  7. SOCIAL EVOLUTION IN ISLAM

    Directory of Open Access Journals (Sweden)

    Ali Muhammad Bhat

    2014-01-01

    Full Text Available Sociology is a systematic study of human relations at social Level. It is a vast concept used to determine the relation of human beings at individual and community level. It includes social interaction accommodation and progress at reasonable levels. Sociologists examine the ways in which social structures and institutions such as class, family, community, power and social problems influence society are dealt with. The evolutionary trend at every step of life helps to accept all changes necessary for human development and prosperity on ethical grounds. The study of society was long known with broad evolutionary reconstructions of historical change in societies. It is a synthesizing field that attempted to integrate the findings acquired from other social sciences. Islam has unique social system and believes in progressive change and help to develop society from nomadic life to international affairs. This change has been possible through many ways for which different terms like Tashakur, Tashkeer, Tafakur etc. were used in Islamic history which are derived from the Quran. An attempt has been made to high light these terms and their impact upon Islamic social evolutionary thought and is explained according to the true nature of evolutionary change and social development.

  8. Chess Evolution Visualization.

    Science.gov (United States)

    Lu, Wei-Li; Wang, Yu-Shuen; Lin, Wen-Chieh

    2014-05-01

    We present a chess visualization to convey the changes in a game over successive generations. It contains a score chart, an evolution graph and a chess board, such that users can understand a game from global to local viewpoints. Unlike current graphical chess tools, which focus only on highlighting pieces that are under attack and require sequential investigation, our visualization shows potential outcomes after a piece is moved and indicates how much tactical advantage the player can have over the opponent. Users can first glance at the score chart to roughly obtain the growth and decline of advantages from both sides, and then examine the position relations and the piece placements, to know how the pieces are controlled and how the strategy works. To achieve this visualization, we compute the decision tree using artificial intelligence to analyze a game, in which each node represents a chess position and each edge connects two positions that are one-move different. We then merge nodes representing the same chess position, and shorten branches where nodes on them contain only two neighbors, in order to achieve readability. During the graph rendering, the nodes containing events such as draws, effective checks and checkmates, are highlighted because they show how a game is ended. As a result, our visualization helps players understand a chess game so that they can efficiently learn strategies and tactics. The presented results, evaluations, and the conducted user studies demonstrate the feasibility of our visualization design.

  9. Evolution of reticular pseudodrusen.

    Science.gov (United States)

    Sarks, John; Arnold, Jennifer; Ho, I-Van; Sarks, Shirley; Killingsworth, Murray

    2011-07-01

    To report observations relating to the clinical recognition and possible basis of reticular pseudodrusen (RPD). This retrospective study reports the evolution of RPD in 166 patients who had follow-up of over 1 year using multiple imaging techniques. Mean age when first seen was 73.3 years and the mean period of observation was 4.9 years (range 1-18 years). Associated macular changes were recorded. RPD were first identified in the upper fundus as a reticular network, which then became less obvious, developing a diffuse yellowish appearance. RPD also faded around choroidal neovascularisation (CNV). RPD therefore could be transient but the pattern often remained visible outside the macula or nasal to the discs. Manifestations of age-related macular degeneration (AMD) were present in nearly all eyes and there was a particularly high association with CNV (52.1%). In one clinicopathological case abnormal material was found in the subretinal space. The prevalence of RPD may be underestimated because their recognition depends upon the imaging method used, the area of fundus examined and the confusion with typical drusen. The pathology of one eye suggests that RPD may correspond to material in the subretinal space.

  10. Evolution of Replication Machines

    Science.gov (United States)

    Yao, Nina Y.; O'Donnell, Mike E.

    2016-01-01

    The machines that decode and regulate genetic information require the translation, transcription and replication pathways essential to all living cells. Thus, it might be expected that all cells share the same basic machinery for these pathways that were inherited from the primordial ancestor cell from which they evolved. A clear example of this is found in the translation machinery that converts RNA sequence to protein. The translation process requires numerous structural and catalytic RNAs and proteins, the central factors of which are homologous in all three domains of life, bacteria, archaea and eukarya. Likewise, the central actor in transcription, RNA polymerase, shows homology among the catalytic subunits in bacteria, archaea and eukarya. In contrast, while some “gears” of the genome replication machinery are homologous in all domains of life, most components of the replication machine appear to be unrelated between bacteria and those of archaea and eukarya. This review will compare and contrast the central proteins of the “replisome” machines that duplicate DNA in bacteria, archaea and eukarya, with an eye to understanding the issues surrounding the evolution of the DNA replication apparatus. PMID:27160337

  11. Thioredoxin and evolution

    Science.gov (United States)

    Buchanan, B. B.

    1991-01-01

    Comparisons of primary structure have revealed significant homology between the m type thioredoxins of chloroplasts and the thioredoxins from a variety of bacteria. Chloroplast thioredoxin f, by comparison, remains an enigma: certain residues are invariant with those of the other thioredoxins, but a phylogenetic relationship to bacterial or m thioredoxins seems distant. Knowledge of the evolutionary history of thioredoxin f is, nevertheless, of interest because of its role in photosynthesis. Therefore, we have attempted to gain information on the evolutionary history of chloroplast thioredoxin f, as well as m. Our goal was first to establish the utility of thioredoxin as a phylogenetic marker, and, if found suitable, to deduce the evolutionary histories of the chloroplast thioredoxins. To this end, we have constructed phylogenetic (minimal replacement) trees using computer analysis. The results show that the thioredoxins of bacteria and animals fall into distinct phylogenetic groups - the bacterial group resembling that derived from earlier 16s RNA analysis and the animal group showing a cluster consistent with known relationships. The chloroplast thioredoxins show a novel type of phylogenetic arrangement: one m type aligns with its counterpart of eukaryotic algae, cyanobacteria and other bacteria, whereas the second type (f type) tracks with animal thioredoxin. The results give new insight into the evolution of photosynthesis.

  12. Freud and evolution.

    Science.gov (United States)

    Scharbert, Gerhard

    2009-01-01

    The essay analyzes the influence of evolutionary thought in the work of Sigmund Freud. Based on Freud's initial occupation as a neuro-anatomist and physiologist certain aspects stemming from the history of nature and developmental biological reasoning that played a role in his endeavours to find a new basis for medical psychology will be pointed out. These considerations are to be regarded as prolegomena of the task to reread Freud once again, and in doing so avoiding the verdict that holds his neuro-anatomic and comparative-morphological works as simply "pre-analytic." In fact, the time seems ripe to reconsider in a new context particularly those evolutionary, medical, and cultural-scientific elements in Freud's work that appear inconsistent at first sight. The substantial thesis is that Freud, given the fact that he was trained in comparative anatomy and physiology in the tradition of Johannes Müller, had the capability of synthesizing elements of this new point of view with the findings and interrogations concerning developmental history and the theory of evolution. More over, this was perceived not merely metaphoric, as he himself stressed it (Freud 1999, XIII, 99), but in the sense of Ubertragung, that inscribed terms and methods deriving from the given field into the realm of psychology. The moving force behind this particular Ubertragung came from a dynamically-neurological perception of the soul that emerged in France since 1800, which Freud came to know trough the late work of Charcot.

  13. Evolution, reproduction and autopoiesis

    Directory of Open Access Journals (Sweden)

    Francois Durand

    2017-11-01

    Full Text Available The term autopoiesis was coined to describe the regenerating and self-maintaining chemical systems of cells. The term has subsequently been applied to many different fields, including sociology, systems theory and information systems. This theory postulates that an autopoietic unity (cell, machine is an organised network of processes that exists in a delimited space, which produces components which in turn continuously regenerate and create the network of processes that produced them. The Santiago Theory of Cognition grew from the Theory of Allopoiesis stating that all living systems are cognitive systems, and the process of living is a process of cognition. Cognition is the ability to adapt to a certain environment and cognition emerges because of a continuous bilateral interaction between the system and its environment. The resultant complexity seen in living systems is caused by this interaction between the system and its environment. Autopoiesis and cognition are however opposing concepts because cognition can only exist when the system is open and not closed as autopoiesis suggests. It is also difficult to see how autopoietic systems could originate if they are closed and how the continuous change which we see in evolution can be explained if life consists of autopoietic systems. It is postulated that cells and organisms are in fact open systems relating genetically to ancestors before them and their ever-changing descendants after them and the flow of molecules and energy through an ever-changing ecology.

  14. SRP reactor safety evolution

    International Nuclear Information System (INIS)

    Rankin, D.B.

    1984-01-01

    The Savannah River Plant reactors have operated for over 100 reactor years without an incident of significant consequence to on or off-site personnel. The reactor safety posture incorporates a conservative, failure-tolerant design; extensive administrative controls carried out through detailed operating and emergency written procedures; and multiple engineered safety systems backed by comprehensive safety analyses, adapting through the years as operating experience, changes in reactor operational modes, equipment modernization, and experience in the nuclear power industry suggested. Independent technical reviews and audits as well as a strong organizational structure also contribute to the defense-in-depth safety posture. A complete review of safety history would discuss all of the above contributors and the interplay of roles. This report, however, is limited to evolution of the engineered safety features and some of the supporting analyses. The discussion of safety history is divided into finite periods of operating history for preservation of historical perspective and ease of understanding by the reader. Programs in progress are also included. The accident at Three Mile Island was assessed for its safety implications to SRP operation. Resulting recommendations and their current status are discussed separately at the end of the report. 16 refs., 3 figs

  15. Schramm–Loewner evolution

    CERN Document Server

    Kemppainen, Antti

    2017-01-01

    This book is a short, but complete, introduction to the Loewner equation and the SLEs, which are a family of random fractal curves, as well as the relevant background in probability and complex analysis. The connection to statistical physics is also developed in the text in an example case. The book is based on a course (with the same title) lectured by the author. First three chapters are devoted to the background material, but at the same time, give the reader a good understanding on the overview on the subject and on some aspects of conformal invariance. The chapter on the Loewner equation develops in detail the connection of growing hulls and the differential equation satisfied by families of conformal maps. The Schramm–Loewner evolutions are defined and their basic properties are studied in the following chapter, and the regularity properties of random curves as well as scaling limits of discrete random curves are investigated in the final chapter. The book is aimed at graduate students or researcher...

  16. Sponsorship in evolution.

    Science.gov (United States)

    Grant, M K

    1990-09-01

    Sponsorship appears to be evolving from an original model in which the sponsoring religious institute related to its facilities in a manner resembling a family business, to a model of sponsorship akin to a franchise, to a ministerial partnership. Factors leading to this evolution include tremendous changes within the religious institute itself, including decreases in the number of members and financial stability. Changes within healthcare itself--such as greater competition and declining revenues-have forced hospitals to diversify. One result of these developments has been a radical change in the "rules" of the game. Historically independent entities--hospitals, sponsors, physicians--now have to value interdependence and mutuality. In the family-run model the family (sponsor) had special privileges, as though they "owned" the business. When the number of family members dropped below that necessary to govern, administer, and staff the institute's facilities, they began to move away from the family model to the franchise model, which has more open communication, greater input to decision making by non-family members, and a shift in the family's attention from actual operations to oversight and accountability. Eventually, the franchise model began to give way to the ministerial partnership, characterized by mutuality. Both family and others have roles not only in carrying out the mission, but in actually shaping and forming it.

  17. Tectonic evolution of Mars

    International Nuclear Information System (INIS)

    Wise, D.U.; Golombek, M.P.; McGill, G.E.

    1979-01-01

    Any model for the tectonic evolution of Mars must account for two major crustal elements: the Tharsis bulge and the topographically low and lightly crated northern third of the planet. Ages determined by crater density indicate that both of these elements came into existence very early in Martian history, a conclusion that holds no matter which of the current crater density versus age curves is used. The size of these two major crustal elements and their sequential development suggest that both may be related to a global-scale internal process. It is proposed that the resurfacing of the northern third of Mars is related to subcrustal erosion and isostatic foundering during the life of a first-order convection cell. With the demise of the cell, denser segregations of metallic materials began to coalesce as a gravitatively unstable layer which finally overturned to form the core. In the overturn, lighter crustal materials was shifted laterally and underplated beneath Tharsis to cause rapid and permanent isostatic rise. This was followed by a long-lived thermal phase produced by the hot underplate and by the gravitative energy of core formation slowly making its way to the surface to produce the Tharsis volcanics

  18. The evolution of programs

    CERN Document Server

    Dershowitz, Nachum

    1983-01-01

    -Ecclesiastes 12:12 Programs are invariably subjected to many rorms or transrormation. After an initial version of a program has been designed and developed, it undergoes debugging and certification. In addition, most long-lived pro­ grams have a liCe-cycle that includes modifications to meet amended specifications and extensions for expanded capabilities. Such evolution­ ary aspects of programming are the topic of this monograph. We present rormal methods for manipulating programs and illustrate their applica­ tion with numerous examples. Such methods could be incorporated in semi-automated programming environments, where they would serve to ease the burden on the programmer. We begin by describing a method whereby a given program that achieves one goal can be modified to achieve a different goal or a pro­ gram that computes wrong results can be debugged to achieve the 2 Preface intended results. The abstraction of a set of cognate programs to obtain a program schema, and the instantiation of abstract sc...

  19. Interspecific Plastome Recombination Reflects Ancient Reticulate Evolution in Picea (Pinaceae).

    Science.gov (United States)

    Sullivan, Alexis R; Schiffthaler, Bastian; Thompson, Stacey Lee; Street, Nathaniel R; Wang, Xiao-Ru

    2017-07-01

    Plastid sequences are a cornerstone in plant systematic studies and key aspects of their evolution, such as uniparental inheritance and absent recombination, are often treated as axioms. While exceptions to these assumptions can profoundly influence evolutionary inference, detecting them can require extensive sampling, abundant sequence data, and detailed testing. Using advancements in high-throughput sequencing, we analyzed the whole plastomes of 65 accessions of Picea, a genus of ∼35 coniferous forest tree species, to test for deviations from canonical plastome evolution. Using complementary hypothesis and data-driven tests, we found evidence for chimeric plastomes generated by interspecific hybridization and recombination in the clade comprising Norway spruce (P. abies) and 10 other species. Support for interspecific recombination remained after controlling for sequence saturation, positive selection, and potential alignment artifacts. These results reconcile previous conflicting plastid-based phylogenies and strengthen the mounting evidence of reticulate evolution in Picea. Given the relatively high frequency of hybridization and biparental plastid inheritance in plants, we suggest interspecific plastome recombination may be more widespread than currently appreciated and could underlie reported cases of discordant plastid phylogenies. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  20. Bioattractors: dynamical systems theory and the evolution of regulatory processes

    Science.gov (United States)

    Jaeger, Johannes; Monk, Nick

    2014-01-01

    In this paper, we illustrate how dynamical systems theory can provide a unifying conceptual framework for evolution of biological regulatory systems. Our argument is that the genotype–phenotype map can be characterized by the phase portrait of the underlying regulatory process. The features of this portrait – such as attractors with associated basins and their bifurcations – define the regulatory and evolutionary potential of a system. We show how the geometric analysis of phase space connects Waddington's epigenetic landscape to recent computational approaches for the study of robustness and evolvability in network evolution. We discuss how the geometry of phase space determines the probability of possible phenotypic transitions. Finally, we demonstrate how the active, self-organizing role of the environment in phenotypic evolution can be understood in terms of dynamical systems concepts. This approach yields mechanistic explanations that go beyond insights based on the simulation of evolving regulatory networks alone. Its predictions can now be tested by studying specific, experimentally tractable regulatory systems using the tools of modern systems biology. A systematic exploration of such systems will enable us to understand better the nature and origin of the phenotypic variability, which provides the substrate for evolution by natural selection. PMID:24882812

  1. Participation costs can suppress the evolution of upstream reciprocity.

    Science.gov (United States)

    Peña, Jorge; Pestelacci, Enea; Berchtold, André; Tomassini, Marco

    2011-03-21

    Indirect reciprocity, one of the many mechanisms proposed to explain the evolution of cooperation, is the idea that altruistic actions can be rewarded by third parties. Upstream or generalized reciprocity is one type of indirect reciprocity in which individuals help someone if they have been helped by somebody else in the past. Although empirically found to be at work in humans, the evolution of upstream reciprocity is difficult to explain from a theoretical point of view. A recent model of upstream reciprocity, first proposed by Nowak and Roch (2007) and further analyzed by Iwagami and Masuda (2010), shows that while upstream reciprocity alone does not lead to the evolution of cooperation, it can act in tandem with mechanisms such as network reciprocity and increase the total level of cooperativity in the population. We argue, however, that Nowak and Roch's model systematically leads to non-uniform interaction rates, where more cooperative individuals take part in more games than less cooperative ones. As a result, the critical benefit-to-cost ratios derived under this model in previous studies are not invariant with respect to the addition of participation costs. We show that accounting for these costs can hinder and even suppress the evolution of upstream reciprocity, both for populations with non-random encounters and graph-structured populations. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Shell evolution of stable N = 50-56 Zr and Mo nuclei with respect to low-lying octupole excitations

    Energy Technology Data Exchange (ETDEWEB)

    Gregor, E.T.; Scheck, M.; Chapman, R.; Gaffney, L.P.; Keatings, J.; Mashtakov, K.R.; O' Donnell, D.; Smith, J.F.; Spagnoletti, P.; Wiseman, C. [University of the West of Scotland, School of Engineering and Computing, Paisley (United Kingdom); SUPA, Scottish Universities Physics Alliance, Glasgow (United Kingdom); Thuerauf, M.; Werner, V. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany)

    2017-03-15

    For the N = 50-56 zirconium (Z = 40) and molybdenum (Z = 42) isotopes, the evolution of subshells is evaluated by extracting the effective single-particle energies from available particle-transfer data. The extracted systematic evolution of neutron subshells and the systematics of the excitation energy of the octupole phonons provide evidence for type-II shape coexistence in the Zr isotopes. Employing a simplistic approach, the relative effective single-particle energies are used to estimate whether the formation of low-lying octupole-isovector excitations is possible at the proposed energies. The results raise doubts about this assignment. (orig.)

  3. Universal pacemaker of genome evolution.

    Science.gov (United States)

    Snir, Sagi; Wolf, Yuri I; Koonin, Eugene V

    2012-01-01

    A fundamental observation of comparative genomics is that the distribution of evolution rates across the complete sets of orthologous genes in pairs of related genomes remains virtually unchanged throughout the evolution of life, from bacteria to mammals. The most straightforward explanation for the conservation of this distribution appears to be that the relative evolution rates of all genes remain nearly constant, or in other words, that evolutionary rates of different genes are strongly correlated within each evolving genome. This correlation could be explained by a model that we denoted Universal PaceMaker (UPM) of genome evolution. The UPM model posits that the rate of evolution changes synchronously across genome-wide sets of genes in all evolving lineages. Alternatively, however, the correlation between the evolutionary rates of genes could be a simple consequence of molecular clock (MC). We sought to differentiate between the MC and UPM models by fitting thousands of phylogenetic trees for bacterial and archaeal genes to supertrees that reflect the dominant trend of vertical descent in the evolution of archaea and bacteria and that were constrained according to the two models. The goodness of fit for the UPM model was better than the fit for the MC model, with overwhelming statistical significance, although similarly to the MC, the UPM is strongly overdispersed. Thus, the results of this analysis reveal a universal, genome-wide pacemaker of evolution that could have been in operation throughout the history of life.

  4. Landscape Evolution Modelling-LAPSUS

    Energy Technology Data Exchange (ETDEWEB)

    Baartman, J. E. M.; Temme, A. J. A. M.; Schoorl, J. M.; Claessens, L.; Viveen, W.; Gorp, W. van; Veldkamp, A.

    2009-07-01

    Landscape evolution modelling can make the consequences of landscape evolution hypotheses explicit and theoretically allows for their falsification and improvement. ideally, landscape evolution models (LEMs) combine the results of all relevant landscape forming processes into an ever-adapting digital landscape (e.g. DEM). These processes may act on different spatial and temporal scales. LAPSUS is such a LEM. Processes that have in different studies been included in LAPSUS are water erosion and deposition, landslide activity, creep, solidification, weathering, tectonics and tillage. Process descriptions are as simple and generic as possible, ensuring wide applicability. (Author) 25 refs.

  5. Landscape Evolution Modelling-LAPSUS

    International Nuclear Information System (INIS)

    Baartman, J. E. M.; Temme, A. J. A. M.; Schoorl, J. M.; Claessens, L.; Viveen, W.; Gorp, W. van; Veldkamp, A.

    2009-01-01

    Landscape evolution modelling can make the consequences of landscape evolution hypotheses explicit and theoretically allows for their falsification and improvement. ideally, landscape evolution models (LEMs) combine the results of all relevant landscape forming processes into an ever-adapting digital landscape (e.g. DEM). These processes may act on different spatial and temporal scales. LAPSUS is such a LEM. Processes that have in different studies been included in LAPSUS are water erosion and deposition, landslide activity, creep, solidification, weathering, tectonics and tillage. Process descriptions are as simple and generic as possible, ensuring wide applicability. (Author) 25 refs.

  6. The chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Chiosi, Cesare

    1986-01-01

    The chemical evolution of galaxies is reviewed with particular attention to the theoretical interpretation of the distribution and abundances of elements in stars and the interstellar medium. The paper was presented to the conference on ''The early universe and its evolution'', Erice, Italy, 1986. The metallicity distribution of the solar vicinity, age metallicity relationship, abundance gradients in the galaxy, external galaxies, star formation and evolution, major sites of nucleosynthesis, yields of chemical elements, chemical models, and the galactic disk, are all discussed. (U.K.)

  7. Experimental evolution in budding yeast

    Science.gov (United States)

    Murray, Andrew

    2012-02-01

    I will discuss our progress in analyzing evolution in the budding yeast, Saccharomyces cerevisiae. We take two basic approaches. The first is to try and examine quantitative aspects of evolution, for example by determining how the rate of evolution depends on the mutation rate and the population size or asking whether the rate of mutation is uniform throughout the genome. The second is to try to evolve qualitatively novel, cell biologically interesting phenotypes and track the mutations that are responsible for the phenotype. Our efforts include trying to alter cell morphology, evolve multicellularity, and produce a biological oscillator.

  8. The Longitudinal Evolution of Equatorial Coronal Holes

    Science.gov (United States)

    Krista, Larisza D.; McIntosh, Scott W.; Leamon, Robert J.

    2018-04-01

    In 2011, three satellites—the Solar-Terrestrial RElations Observatory A & B, and the Solar Dynamics Observatory (SDO)—were in a unique spatial alignment that allowed a 360° view of the Sun. This alignment lasted until 2014, the peak of solar cycle 24. Using extreme ultraviolet images and Hovmöller diagrams, we studied the lifetimes and propagation characteristics of coronal holes (CHs) in longitude over several solar rotations. Our initial results show at least three distinct populations of “low-latitude” or “equatorial” CHs (below 65^\\circ latitude). One population rotates in retrograde direction and coincides with a group of long-lived (over sixty days) CHs in each hemisphere. These are typically located between 30° and 55^\\circ , and display velocities of ∼55 m s‑1 slower than the local differential rotation rate. A second, smaller population of CHs rotate prograde, with velocities between ∼20 and 45 m s‑1. This population is also long-lived, but observed ±10° from the solar equator. A third population of CHs are short-lived (less than two solar rotations), and they appear over a wide range of latitudes (±65°) and exhibit velocities between ‑140 and 80 m s‑1. The CH “butterfly diagram” we developed shows a systematic evolution of the longer-lived holes; however, the sample is too short in time to draw conclusions about possible connections to dynamo-related phenomena. An extension of the present work to the 22 years of the combined SOHO–SDO archives is necessary to understand the contribution of CHs to the decadal-scale evolution of the Sun.

  9. A 'Turing' Test for Landscape Evolution Models

    Science.gov (United States)

    Parsons, A. J.; Wise, S. M.; Wainwright, J.; Swift, D. A.

    2008-12-01

    Resolving the interactions among tectonics, climate and surface processes at long timescales has benefited from the development of computer models of landscape evolution. However, testing these Landscape Evolution Models (LEMs) has been piecemeal and partial. We argue that a more systematic approach is required. What is needed is a test that will establish how 'realistic' an LEM is and thus the extent to which its predictions may be trusted. We propose a test based upon the Turing Test of artificial intelligence as a way forward. In 1950 Alan Turing posed the question of whether a machine could think. Rather than attempt to address the question directly he proposed a test in which an interrogator asked questions of a person and a machine, with no means of telling which was which. If the machine's answer could not be distinguished from those of the human, the machine could be said to demonstrate artificial intelligence. By analogy, if an LEM cannot be distinguished from a real landscape it can be deemed to be realistic. The Turing test of intelligence is a test of the way in which a computer behaves. The analogy in the case of an LEM is that it should show realistic behaviour in terms of form and process, both at a given moment in time (punctual) and in the way both form and process evolve over time (dynamic). For some of these behaviours, tests already exist. For example there are numerous morphometric tests of punctual form and measurements of punctual process. The test discussed in this paper provides new ways of assessing dynamic behaviour of an LEM over realistically long timescales. However challenges remain in developing an appropriate suite of challenging tests, in applying these tests to current LEMs and in developing LEMs that pass them.

  10. How to discretize differential systems in a systematic way

    International Nuclear Information System (INIS)

    Murata, M; Satsuma, J; Ramani, A; Grammaticos, B

    2010-01-01

    We present a systematic approach to the construction of discrete analogues for differential systems. Our method is tailored to first-order differential equations and relies on a formal linearization, followed by a Pade-like rational approximation of an exponential evolution operator. We apply our method to a host of systems for which there exist discretization results obtained by what we call the 'intuitive' method and compare the discretizations obtained. A discussion of our method as compared to one of the Mickens is also presented. Finally we apply our method to a system of coupled Riccati equations with emphasis on the preservation of the integrable character of the differential system.

  11. Evolution of rhinology.

    Science.gov (United States)

    Kaluskar, S K

    2008-06-01

    The study of the nose is as old as civilisation. Various conditions affecting its structure and function has been documented in Edwin Smith Papyrus in hieroglyphic script, an Egyptian writing system of the mid -4th Millennium BC.The major contribution for the complete reconstruction of the nose originated in India by Sushruta in around 600 BC. Writing in Sanskrit in the form of verses he described in detail the technique of total reconstruction, which is still being practiced today as Indian Rhinoplasty. This surgical reconstruction paved the way to modern plastic surgery in Europe and United States in 18th century. Sushruta contributed not only to the plastic surgery of the nose, but described entire philosophy of Head and Neck and other surgery as well. Other notable contributors were Greek physicians, Hippocrate and Galen, and at the birth of the Christianity, Celsus wrote eight books of medical encyclopaedia, which described various conditions affecting nose.Septal and Sinus surgery, in comparison to rhinoplasty did not develop until 17th century. Septal surgery began with total septectomy, sub mucous resection by Killian & Freer in early 20th century and later septoplasty by Cottle in middle of 20th century.Sinus surgery probably originated in Egypt, where instruments were used to remove brain through the ethmoid sinuses as part of the mummification process. In 18th century, empyema of the maxillary sinus was drained through the tooth socket or anterior wall of the sinus, which lead to the evolution of radical procedures of removal of mucous membrane and inferior meatal antrostomy. In the late 20th century, improved understanding of the mucociliary mechanism described by Prof. Messerklinger and Nasal Endoscopy described by Prof. Draf with the development of fibre optics and CT imaging, heralded a new era, which evolved in functional endoscopic sinus surgery. New technology further enhanced the scope of endoscope being used "around and beyond" the nose.

  12. Mechanisms of oxygen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Radmer, R; Cheniae, G

    1976-08-01

    The production of O/sub 2/ from water requires the collaboration of four oxidizing equivalents. When dark-adapted O/sub 2/ evolving photosynthetic material is illuminated by a sequence of short (less than 2 ..mu..sec) saturating flashes, the amount of O/sub 2/ evolved per flash oscillates with a period of four. This indicates that a charge-collector, operating with its own reaction center, successively collects and stores four oxidizing equivalents, which are used in a concerted oxidation of two water molecules. Luminescence, fluorescence, and pH changes also reflect this cycle of four. The O/sub 2/ precursor states are quite stable; under some conditions they can have a lifetime of several minutes. The O/sub 2/-yielding reactions and reactions associated with trap recovery are fast relative to the rate-limiting step of photosynthesis. The molecular identity of the charge-collector is unknown, but correlative evidence suggests that a manganese containing catalyst (approximately 4 Mn/charge collector) participates, possibly directly. Formation of the active Mn-containing catalyst occurs via a multi-quantum process occurring within the System II reaction center. The photoactivated catalyst, located on the inner face of the thylakoid membrane, remains permanently active and essentially inaccessible to chemicals other than analogs of H/sub 2/O (e.g., NH/sub 3/, NH/sub 2/OH). This O/sub 2/ evolving catalyst can be deactivated by a variety of treatments that do not alter the system II reaction center. Anions such as chloride seem to participate rather directly in the O/sub 2/ evolution process via unknown mechanism(s).

  13. Methods To Identify Aptamers against Cell Surface Biomarkers

    Directory of Open Access Journals (Sweden)

    Frédéric Ducongé

    2011-09-01

    Full Text Available Aptamers are nucleic acid-based ligands identified through a process of molecular evolution named SELEX (Systematic Evolution of Ligands by Exponential enrichment. During the last 10-15 years, numerous aptamers have been developed specifically against targets present on or associated with the surface of human cells or infectious pathogens such as viruses, bacteria, fungi or parasites. Several of the aptamers have been described as potent probes, rivalling antibodies, for use in flow cytometry or microscopy. Some have also been used as drugs by inhibiting or activating functions of their targets in a manner similar to neutralizing or agonistic antibodies. Additionally, it is straightforward to conjugate aptamers to other agents without losing their affinity and they have successfully been used in vitro and in vivo to deliver drugs, siRNA, nanoparticles or contrast agents to target cells. Hence, aptamers identified against cell surface biomarkers represent a promising class of ligands. This review presents the different strategies of SELEX that have been developed to identify aptamers for cell surface-associated proteins as well as some of the methods that are used to study their binding on living cells.

  14. The evolution of alliance capabilities

    NARCIS (Netherlands)

    Heimeriks, K.H.; Duysters, G.M.; Vanhaverbeke, W.P.M.

    2004-01-01

    This paper assesses the effectiveness and differential performance effects of learning mechanisms on the evolution of alliance capabilities. Relying on the concept of capability lifecycles, prior research has suggested that different capability levels could be identified in which different

  15. Linguistics: evolution and language change.

    Science.gov (United States)

    Bowern, Claire

    2015-01-05

    Linguists have long identified sound changes that occur in parallel. Now novel research shows how Bayesian modeling can capture complex concerted changes, revealing how evolution of sounds proceeds. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Giant lobelias exemplify convergent evolution

    Directory of Open Access Journals (Sweden)

    Givnish Thomas J

    2010-01-01

    Full Text Available Abstract Giant lobeliads on tropical mountains in East Africa and Hawaii have highly unusual, giant-rosette growth forms that appear to be convergent on each other and on those of several independently evolved groups of Asteraceae and other families. A recent phylogenetic analysis by Antonelli, based on sequencing the widest selection of lobeliads to date, raises doubts about this paradigmatic example of convergent evolution. Here I address the kinds of evidence needed to test for convergent evolution and argue that the analysis by Antonelli fails on four points. Antonelli's analysis makes several important contributions to our understanding of lobeliad evolution and geographic spread, but his claim regarding convergence appears to be invalid. Giant lobeliads in Hawaii and Africa represent paradigmatic examples of convergent evolution.

  17. Evolution, Fruit Flies and Gerontology

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 11. Evolution, Fruit Flies and Gerontology Evolutionary Biology Helps Unravel the Mysteries of Ageing. Amitabh Joshi. General Article Volume 1 Issue 11 November 1996 pp 51-63 ...

  18. Evolution of ageing since Darwin

    Indian Academy of Sciences (India)

    2008-12-23

    Dec 23, 2008 ... causes of senescence in terms of evolution by natural selec- tion. He rejected the historical ... ism's longevity was somehow determined by its physiolog- ..... Gavrilov L. A. and Gavrilova N. S. 1991 The biology of life span: a.

  19. Towards an alternative evolution model.

    Science.gov (United States)

    van Waesberghe, H

    1982-01-01

    Lamarck and Darwin agreed on the inconstancy of species and on the exclusive gradualism of evolution (nature does not jump). Darwinism, revived as neo-Darwinism, was almost generally accepted from about 1930 till 1960. In the sixties the evolutionary importance of selection has been called in question by the neutralists. The traditional conception of the gene is disarranged by recent molecular-biological findings. Owing to the increasing confusion about the concept of genotype, this concept is reconsidered. The idea of the genotype as a cluster of genes is replaced by a cybernetical interpretation of the genotype. As nature does jump, exclusive gradualism is dismissed. Saltatory evolution is a natural phenomenon, provided by a sudden collapse of the thresholds which resist against evolution. The fossil record and the taxonomic system call for a macromutational interpretation. As Lamarck and Darwin overlooked the resistance of evolutionary thresholds, an alternative evolution model is needed, the first to be constructed on a palaeontological and taxonomic basis.

  20. Biological evolution: Some genetic considerations

    African Journals Online (AJOL)

    Mohammad Saad Zaghloul Salem

    2013-12-08

    Dec 8, 2013 ... cept of evolution, viz. genetic memory and evolutionary variations, genomic adaptations to stress .... or codons, along the transcript without giving attention to whether they are ... They do not affect the genome in a straightfor-.

  1. Weak interactions and presupernova evolution

    International Nuclear Information System (INIS)

    Aufderheide, M.B.; State Univ. of New York

    1991-01-01

    The role of weak interactions, particularly electron capture and β - decay, in presupernova evolution is discussed. The present uncertainty in these rates is examined and the possibility of improving the situation is addressed. 12 refs., 4 figs

  2. "Systematizing" ethics consultation services.

    Science.gov (United States)

    Bruce, Courtenay R; Eves, Margot M; Allen, Nathan G; Smith, Martin L; Peña, Adam M; Cheney, John R; Majumder, Mary A

    2015-03-01

    While valuable work has been done addressing clinical ethics within established healthcare systems, we anticipate that the projected growth in acquisitions of community hospitals and facilities by large tertiary hospitals will impact the field of clinical ethics and the day-to-day responsibilities of clinical ethicists in ways that have yet to be explored. Toward the goal of providing clinical ethicists guidance on a range of issues that they may encounter in the systematization process, we discuss key considerations and potential challenges in implementing system-wide ethics consultation services. Specifically, we identify four models for organizing, developing, and enhancing ethics consultation activities within a system created through acquisitions: (1) train-the-trainer, (2) local capacity-building, (3) circuit-riding, and (4) consolidated accountability. We note each model's benefits and challenges. To our knowledge, this is the first paper to consider the broader landscape of issues affected by consolidation. We anticipate that clinical ethicists, volunteer consultants, and hospital administrators will benefit from our recommendations.

  3. Aromatherapy: a systematic review.

    Science.gov (United States)

    Cooke, B; Ernst, E

    2000-01-01

    Aromatherapy is becoming increasingly popular; however there are few clear indications for its use. To systematically review the literature on aromatherapy in order to discover whether any clinical indication may be recommended for its use, computerised literature searches were performed to retrieve all randomised controlled trials of aromatherapy from the following databases: MEDLINE, EMBASE, British Nursing Index, CISCOM, and AMED. The methodological quality of the trials was assessed using the Jadad score. All trials were evaluated independently by both authors and data were extracted in a pre-defined, standardised fashion. Twelve trials were located: six of them had no independent replication; six related to the relaxing effects of aromatherapy combined with massage. These studies suggest that aromatherapy massage has a mild, transient anxiolytic effect. Based on a critical assessment of the six studies relating to relaxation, the effects of aromatherapy are probably not strong enough for it to be considered for the treatment of anxiety. The hypothesis that it is effective for any other indication is not supported by the findings of rigorous clinical trials. PMID:10962794

  4. Evolution of White Dwarf Stars

    OpenAIRE

    L. G. Althaus

    2001-01-01

    This paper is aimed at presenting the main results we have obtained for the study of the evoution of white dwarf stars. The calculations are carried out by means of a detailed evolutionary code based on an updated physical description. In particular, we briefly discuss the results for the evolution of white dwarfs of different stellar masses and chemical composition, and the evolution of whit e dwarfs in the framework of a varying gravitational constant G scenario as well.

  5. Evolution, religions and global Bioethics

    OpenAIRE

    Perbal, Laurence

    2007-01-01

    Creationist theories are still present in the United States and in Europe. The Darwinian theory of evolution is often considered as the starting point of important debates between religions and evolutionists. In this paper, we are principally interested in evolutionary creationism (or theistic evolutionism). The existence of a divine design in nature, the spiritual status of human beings and the emergence of human species as the purpose of evolution are some of those debates. The post-Darwini...

  6. Physical Complexity and Cognitive Evolution

    Science.gov (United States)

    Jedlicka, Peter

    Our intuition tells us that there is a general trend in the evolution of nature, a trend towards greater complexity. However, there are several definitions of complexity and hence it is difficult to argue for or against the validity of this intuition. Christoph Adami has recently introduced a novel measure called physical complexity that assigns low complexity to both ordered and random systems and high complexity to those in between. Physical complexity measures the amount of information that an organism stores in its genome about the environment in which it evolves. The theory of physical complexity predicts that evolution increases the amount of `knowledge' an organism accumulates about its niche. It might be fruitful to generalize Adami's concept of complexity to the entire evolution (including the evolution of man). Physical complexity fits nicely into the philosophical framework of cognitive biology which considers biological evolution as a progressing process of accumulation of knowledge (as a gradual increase of epistemic complexity). According to this paradigm, evolution is a cognitive `ratchet' that pushes the organisms unidirectionally towards higher complexity. Dynamic environment continually creates problems to be solved. To survive in the environment means to solve the problem, and the solution is an embodied knowledge. Cognitive biology (as well as the theory of physical complexity) uses the concepts of information and entropy and views the evolution from both the information-theoretical and thermodynamical perspective. Concerning humans as conscious beings, it seems necessary to postulate an emergence of a new kind of knowledge - a self-aware and self-referential knowledge. Appearence of selfreflection in evolution indicates that the human brain reached a new qualitative level in the epistemic complexity.

  7. Evolution of the European region

    International Nuclear Information System (INIS)

    Jeger, Eh.

    1984-01-01

    The problem on geochronological study of the European region is covered. The most ancient age values are determined by U-Pb methods by zircones from paragneisses. The model of evolution, being in agreement with the data obtained by U-Pb and Rb-Sr methods, is considered. The history of the Schwarzwald development is typical for the continent as a whole. The diagram of evolution of primary 87 Sr/ 86 Sr for orthogneisses and granites in France is given

  8. Biological evolution: Some genetic considerations

    OpenAIRE

    Salem, Mohammad Saad Zaghloul

    2014-01-01

    Background: The concept of biological evolution has long been accepted as a palatable theory aiming at explaining how life began and how creatures diverged so widely along the life span of the earth. Meticulous analysis and criticism of the different postulations of this concept, however, reveals that evolution is an illogic concept based on theoretical hypotheses that can never be tested. Creation, on the other hand, represents the other side of the coin, and up till now debates confronting ...

  9. Qutrit squeezing via semiclassical evolution

    International Nuclear Information System (INIS)

    Klimov, Andrei B; Dinani, Hossein Tavakoli; Medendorp, Zachari E D; Guise, Hubert de

    2011-01-01

    We introduce a concept of squeezing in collective qutrit systems through a geometrical picture connected to the deformation of the isotropic fluctuations of su(3) operators when evaluated in a coherent state. This kind of squeezing can be generated by Hamiltonians nonlinear in the generators of su(3) algebra. A simplest model of such a nonlinear evolution is analyzed in terms of semiclassical evolution of the SU(3) Wigner function. (paper)

  10. Symmetry and topology in evolution

    International Nuclear Information System (INIS)

    Lukacs, B.; Berczi, S.; Molnar, I.; Paal, G.

    1991-10-01

    This volume contains papers of an interdisciplinary symposium on evolution. The aim of this symposium, held in Budapest, Hungary, 28-29 May 1991, was to clear the role of symmetry and topology at different levels of the evolutionary processes. 21 papers were presented, their topics included evolution of the Universe, symmetry of elementary particles, asymmetry of the Earth, symmetry and asymmetry of biomolecules, symmetry and topology of lining objects, human asymmetry etc. (R.P.)

  11. Entanglement and inhibited quantum evolution

    International Nuclear Information System (INIS)

    Toschek, P E; Balzer, Chr; Hannemann, Th; Wunderlich, Ch; Neuhauser, W

    2003-01-01

    The evolution of a quantum system is impeded by the system's state being observed. A test on an ensemble neither proves the causal nexus nor discloses the nature of the inhibition. Two recent experiments that make use of sequential optical or microwave-optical double resonance on an individual trapped ion disprove a dynamical effect of back action by meter or environment. They rather indicate the ionic states involved in the evolution being entangled with the potentially recorded bivalued scattered-light signal

  12. Thermodynamic evolution far from equilibrium

    Science.gov (United States)

    Khantuleva, Tatiana A.

    2018-05-01

    The presented model of thermodynamic evolution of an open system far from equilibrium is based on the modern results of nonequilibrium statistical mechanics, the nonlocal theory of nonequilibrium transport developed by the author and the Speed Gradient principle introduced in the theory of adaptive control. Transition to a description of the system internal structure evolution at the mesoscopic level allows a new insight at the stability problem of non-equilibrium processes. The new model is used in a number of specific tasks.

  13. The evolution of single stars

    International Nuclear Information System (INIS)

    Tayler, R.J.

    1982-01-01

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

  14. Modelling Geomorphic Systems: Landscape Evolution

    OpenAIRE

    Valters, Declan

    2016-01-01

    Landscape evolution models (LEMs) present the geomorphologist with a means of investigating how landscapes evolve in response to external forcings, such as climate and tectonics, as well as internal process laws. LEMs typically incorporate a range of different geomorphic transport laws integrated in a way that simulates the evolution of a 3D terrain surface forward through time. The strengths of LEMs as research tools lie in their ability to rapidly test many different hypotheses of landscape...

  15. Evolution of Isolated Neutron Stars

    OpenAIRE

    Popov, S. B.

    2001-01-01

    In this paper we briefly review our recent results on evolution and properties of isolated neutron stars (INSs) in the Galaxy. As the first step we discuss stochastic period evolution of INSs. We briefly discuss how an INS's spin period evolves under influence of interaction with turbulized interstellar medium. To investigate statistical properties of the INS population we calculate a {\\it census} of INSs in our Galaxy. Then we show that for exponential field decay the range of minimum value ...

  16. Cultural commons and cultural evolution

    OpenAIRE

    Bravo, Giangiacomo

    2010-01-01

    Culture evolves following a process that is akin to biological evolution, although with some significant differences. At the same time culture has often a collective good value for human groups. This paper studies culture in an evolutionary perspective, with a focus on the implications of group definition for the coexistence of different cultures. A model of cultural evolution is presented where agents interacts in an artificial environment. The belonging to a specific memetic group is a majo...

  17. Systematic Reviews in Sports Medicine.

    Science.gov (United States)

    DiSilvestro, Kevin J; Tjoumakaris, Fotios P; Maltenfort, Mitchell G; Spindler, Kurt P; Freedman, Kevin B

    2016-02-01

    The number of systematic reviews published in the orthopaedic literature has increased, and these reviews can help guide clinical decision making. However, the quality of these reviews can affect the reader's ability to use the data to arrive at accurate conclusions and make clinical decisions. To evaluate the methodological and reporting quality of systematic reviews and meta-analyses in the sports medicine literature to determine whether such reviews should be used to guide treatment decisions. The hypothesis was that many systematic reviews in the orthopaedic sports medicine literature may not follow the appropriate reporting guidelines or methodological criteria recommended for systematic reviews. Systematic review. All clinical sports medicine systematic reviews and meta-analyses from 2009 to 2013 published in The American Journal of Sports Medicine (AJSM), The Journal of Bone and Joint Surgery (JBJS), Arthroscopy, Sports Health, and Knee Surgery, Sports Traumatology, Arthroscopy (KSSTA) were reviewed and evaluated for level of evidence according to the guidelines from the Oxford Centre for Evidence-Based Medicine, for reporting quality according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, and for methodological quality according to the Assessment of Multiple Systematic Reviews (AMSTAR) tool. Analysis was performed by year and journal of publication, and the levels of evidence included in the systematic reviews were also analyzed. A total of 200 systematic reviews and meta-analyses were identified over the study period. Of these, 53% included evidence levels 4 and 5 in their analyses, with just 32% including evidence levels 1 and 2 only. There were significant differences in the proportion of articles with high levels of evidence (P Systematic reviews and meta-analyses in orthopaedics sports medicine literature relied on evidence levels 4 and 5 in 53% of studies over the 5-year study period. Overall, PRISMA and

  18. Phylogenomic Insights into Animal Evolution.

    Science.gov (United States)

    Telford, Maximilian J; Budd, Graham E; Philippe, Hervé

    2015-10-05

    Animals make up only a small fraction of the eukaryotic tree of life, yet, from our vantage point as members of the animal kingdom, the evolution of the bewildering diversity of animal forms is endlessly fascinating. In the century following the publication of Darwin's Origin of Species, hypotheses regarding the evolution of the major branches of the animal kingdom - their relationships to each other and the evolution of their body plans - was based on a consideration of the morphological and developmental characteristics of the different animal groups. This morphology-based approach had many successes but important aspects of the evolutionary tree remained disputed. In the past three decades, molecular data, most obviously primary sequences of DNA and proteins, have provided an estimate of animal phylogeny largely independent of the morphological evolution we would ultimately like to understand. The molecular tree that has evolved over the past three decades has drastically altered our view of animal phylogeny and many aspects of the tree are no longer contentious. The focus of molecular studies on relationships between animal groups means, however, that the discipline has become somewhat divorced from the underlying biology and from the morphological characteristics whose evolution we aim to understand. Here, we consider what we currently know of animal phylogeny; what aspects we are still uncertain about and what our improved understanding of animal phylogeny can tell us about the evolution of the great diversity of animal life. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Binary evolution and observational constraints

    International Nuclear Information System (INIS)

    Loore, C. de

    1984-01-01

    The evolution of close binaries is discussed in connection with problems concerning mass and angular momentum losses. Theoretical and observational evidence for outflow of matter, leaving the system during evolution is given: statistics on total masses and mass ratios, effects of the accretion of the mass gaining component, the presence of streams, disks, rings, circumstellar envelopes, period changes, abundance changes in the atmosphere. The effects of outflowing matter on the evolution is outlined, and estimates of the fraction of matter expelled by the loser, and leaving the system, are given. The various time scales involved with evolution and observation are compared. Examples of non conservative evolution are discussed. Problems related to contact phases, on mass and energy losses, in connection with entropy changes are briefly analysed. For advanced stages the disruption probabilities for supernova explosions are examined. A global picture is given for the evolution of massive close binaries, from ZAMS, through WR phases, X-ray phases, leading to runaway pulsars or to a binary pulsar and later to a millisecond pulsar. (Auth.)

  20. Factorizing the time evolution operator

    International Nuclear Information System (INIS)

    Garcia Quijas, P C; Arevalo Aguilar, L M

    2007-01-01

    There is a widespread belief in the quantum physical community, and textbooks used to teach quantum mechanics, that it is a difficult task to apply the time evolution operator e itH-hat/h on an initial wavefunction. Because the Hamiltonian operator is, generally, the sum of two operators, then it is not possible to apply the time evolution operator on an initial wavefunction ψ(x, 0), for it implies using terms like (a-hat + b-hat). A possible solution is to factorize the time evolution operator and then apply successively the individual exponential operator on the initial wavefunction. However, the exponential operator does not directly factorize, i.e. e a-hat+b-hat ≠ e a-hat e b-hat . In this study we present a useful procedure for factorizing the time evolution operator when the argument of the exponential is a sum of two operators, which obey specific commutation relations. Then, we apply the exponential operator as an evolution operator for the case of elementary unidimensional potentials, like a particle subject to a constant force and a harmonic oscillator. Also, we discuss an apparent paradox concerning the time evolution operator and non-spreading wave packets addressed previously in the literature

  1. Plant domestication slows pest evolution.

    Science.gov (United States)

    Turcotte, Martin M; Lochab, Amaneet K; Turley, Nash E; Johnson, Marc T J

    2015-09-01

    Agricultural practices such as breeding resistant varieties and pesticide use can cause rapid evolution of pest species, but it remains unknown how plant domestication itself impacts pest contemporary evolution. Using experimental evolution on a comparative phylogenetic scale, we compared the evolutionary dynamics of a globally important economic pest - the green peach aphid (Myzus persicae) - growing on 34 plant taxa, represented by 17 crop species and their wild relatives. Domestication slowed aphid evolution by 13.5%, maintained 10.4% greater aphid genotypic diversity and 5.6% higher genotypic richness. The direction of evolution (i.e. which genotypes increased in frequency) differed among independent domestication events but was correlated with specific plant traits. Individual-based simulation models suggested that domestication affects aphid evolution directly by reducing the strength of selection and indirectly by increasing aphid density and thus weakening genetic drift. Our results suggest that phenotypic changes during domestication can alter pest evolutionary dynamics. © 2015 John Wiley & Sons Ltd/CNRS.

  2. The Galaxy Evolution Probe

    Science.gov (United States)

    Glenn, Jason; Galaxy Evolution Probe Team

    2018-01-01

    The Galaxy Evolution Probe (GEP) is a concept for a far-infrared observatory to survey large regions of sky for star-forming galaxies from z = 0 to beyond z = 3. Our knowledge of galaxy formation is incomplete and requires uniform surveys over a large range of redshifts and environments to accurately describe mass assembly, star formation, supermassive black hole growth, interactions between these processes, and what led to their decline from z ~ 2 to the present day. Infrared observations are sensitive to dusty, star-forming galaxies, which have bright polycyclic aromatic hydrocarbon (PAH) emission features and warm dust continuum in the rest-frame mid infrared and cooler thermal dust emission in the far infrared. Unlike previous far-infrared continuum surveys, the GEP will measure photometric redshifts commensurate with galaxy detections from PAH emission and Si absorption features, without the need for obtaining spectroscopic redshifts of faint counterparts at other wavelengths.The GEP design includes a 2 m diameter telescope actively cooled to 4 K and two instruments: (1) An imager covering 10 to 300 um with 25 spectral resolution R ~ 8 bands (with lower R at the longest wavelengths) to detect star-forming galaxies and measure their redshifts photometrically. (2) A 23 – 190 um, R ~ 250 dispersive spectrometer for redshift confirmation and identification of obscured AGN using atomic fine-structure lines. Lines including [Ne V], [O IV], [O III], [O I], and [C II] will probe gas physical conditions, radiation field hardness, and metallicity. Notionally, the GEP will have a two-year mission: galaxy surveys with photometric redshifts in the first year and a second year devoted to follow-up spectroscopy. A comprehensive picture of star formation in galaxies over the last 10 billion years will be assembled from cosmologically relevant volumes, spanning environments from field galaxies and groups, to protoclusters, to dense galaxy clusters.Commissioned by NASA, the

  3. Evolution of plant senescence

    Directory of Open Access Journals (Sweden)

    Young Mike

    2009-07-01

    characteristics of senescence-related genes allow a framework to be constructed of decisive events in the evolution of the senescence syndrome of modern land-plants. Combining phylogenetic, comparative sequence, gene expression and morphogenetic information leads to the conclusion that biochemical, cellular, integrative and adaptive systems were progressively added to the ancient primary core process of senescence as the evolving plant encountered new environmental and developmental contexts.

  4. Energy efficient evolution of mobile broadband networks

    Energy Technology Data Exchange (ETDEWEB)

    Micallef, G.

    2013-04-15

    existing macro base station sites together with the deployment of outdoor or indoor small cells (heterogeneous network) provide the best compromise between performance and power consumption. Focusing on one of the case studies, it is noted that the upgrade of both HSPA and LTE network layers results in the power consumption of the network increasing by a factor of 4. When coupled with the growth in capacity introduced by the various upgrades (x50), the efficiency of the network is still greatly improved. Over the evolution period, the stated increase in power consumption does not consider improvement in base station equipment. By considering a number of different equipment versions, the evolution study is further extended to also include the impact of replacing old equipment. Results show that an aggressive replacement strategy and the upgrade of sites to remote radio head can restrain the increase in power consumption of the network to just 17%. In addition to upgrading equipment, mobile network operators can further reduce power consumption by enabling a number of power saving features. These features often exploit redundancies within the network and/or the variation in traffic over a daily period. An example of such feature is sleep mode, which allows for base station sites to be systematically powered down during hours with low network traffic. While dependent on the traffic profile, within an urban area sleep mode can reduce the daily energy consumption of the network by around 20%. In addition to the different variances of sleep mode, the potential savings of other features are also described. Selecting a power efficient network capacity evolution path, replacing old and less efficient equipment, and enabling power saving features, can all considerably reduce the power consumption of future mobile broadband networks. Studies and recommendations presented within this thesis demonstrate that it is realistic for mobile network operators to boost network capacity by a

  5. Systematic Review Workshop (August 2013)

    Science.gov (United States)

    The goal for this workshop is to receive scientific input regarding approaches for different steps within a systematic review, such as evaluating individual studies, synthesizing evidence within a particular discipline, etc.

  6. SNC meteorites: Clues to martian petrologic evolution

    International Nuclear Information System (INIS)

    McSween, H.Y. Jr.

    1985-01-01

    The shergottites, nakhlites, and Chassigny (SNC meteorites) are apparently cumulate mafic and ultramafic rocks that crystallized at shallow levels in the crust of their parent body. The mineralogy and chemistry of these meteorites are remarkably like equivalent terrestrial rocks, although their ratios of Fe/(Fe+Mg) and certain incompatible elements and their oxygen isotopic compositions are distinctive. All have crystallization ages of 1.3 b.y. or younger and formed from magmas produced by partial melting of previously fractionated source regions. Isotope systematics suggest that the SNC parent body had a complex and protracted thermal history spanning most of geologic time. Some meteorites have been severely shock metamorphosed, and all were ejected from their parent body at relatively recent times, possibly in several impact events. Late crystallization ages, complex petrogenesis, and possible evidence for a large gravitational field suggest that these meteorites are derived from a large planet. Trapped gases in shergottite shock melts have compositions similar to the composition measured in the Martian atmosphere. Ejection of Martian meteorites may have been accomplished by acceleration of near-surface spalls or other mechanisms not fully understood. If SNC meteorites are of Martian origin, they provide important information on planetary composition and evolution. The bulk composition and redox state of the Martian mantle, as constrained by shergottite phase equilibria, must be more earthlike than most current models. Planetary thermal models should benefit from data on the abundances of radioactive heat sources, the melting behavior of the mantle, and the timing of planetary differentiation

  7. The Evolution of Lateralized Brain Circuits

    Directory of Open Access Journals (Sweden)

    Michael C. Corballis

    2017-06-01

    Full Text Available In the vast clade of animals known as the bilateria, cerebral and behavioral asymmetries emerge against the backdrop of bilateral symmetry, with a functional trade-off between the two. Asymmetries can lead to more efficient processing and packaging of internal structures, but at the expense of efficient adaptation to a natural world without systematic left-right bias. Asymmetries may arise through the fissioning of ancestral structures that are largely symmetrical, creating new circuits. In humans these may include asymmetrical adaptations to language and manufacture, and as one or other hemisphere gains dominance for functions that were previously represented bilaterally. This is best illustrated in the evolution of such functions as language and tool manufacture in humans, which may derive from the mirror-neuron system in primates, but similar principles probably apply to the many other asymmetries now evident in a wide range of animals. Asymmetries arise in largely independent manner with multi-genetic sources, rather than as a single over-riding principle.

  8. Systematics in delayed neutron yields

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Takaaki [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

    1998-03-01

    An attempt was made to reproduce the systematic trend observed in the delayed neutron yields for actinides on the basis of the five-Gaussian representation of the fission yield together with available data sets for delayed neutron emission probability. It was found that systematic decrease in DNY for heavier actinides is mainly due to decrease of fission yields of precursors in the lighter side of the light fragment region. (author)

  9. American Muslim Undergraduates' Views on Evolution

    Science.gov (United States)

    Fouad, Khadija Engelbrecht

    2016-01-01

    A qualitative investigation into American Muslim undergraduates' views on evolution revealed three main positions on evolution: theistic evolution, a belief in special creation of all species, and a belief in special creation of humans with evolution for all non-human species. One can conceive of the manner in which respondents chose their…

  10. Student Teachers' Approaches to Teaching Biological Evolution

    Science.gov (United States)

    Borgerding, Lisa A.; Klein, Vanessa A.; Ghosh, Rajlakshmi; Eibel, Albert

    2015-01-01

    Evolution is fundamental to biology and scientific literacy, but teaching high school evolution is often difficult. Evolution teachers face several challenges including limited content knowledge, personal conflicts with evolution, expectations of resistance, concerns about students' conflicts with religion, and curricular constraints. Evolution…

  11. Cyanobacterial evolution during the Precambrian

    Science.gov (United States)

    Schirrmeister, Bettina E.; Sanchez-Baracaldo, Patricia; Wacey, David

    2016-07-01

    Life on Earth has existed for at least 3.5 billion years. Yet, relatively little is known of its evolution during the first two billion years, due to the scarceness and generally poor preservation of fossilized biological material. Cyanobacteria, formerly known as blue green algae were among the first crown Eubacteria to evolve and for more than 2.5 billion years they have strongly influenced Earth's biosphere. Being the only organism where oxygenic photosynthesis has originated, they have oxygenated Earth's atmosphere and hydrosphere, triggered the evolution of plants -being ancestral to chloroplasts- and enabled the evolution of complex life based on aerobic respiration. Having such a strong impact on early life, one might expect that the evolutionary success of this group may also have triggered further biosphere changes during early Earth history. However, very little is known about the early evolution of this phylum and ongoing debates about cyanobacterial fossils, biomarkers and molecular clock analyses highlight the difficulties in this field of research. Although phylogenomic analyses have provided promising glimpses into the early evolution of cyanobacteria, estimated divergence ages are often very uncertain, because of vague and insufficient tree-calibrations. Results of molecular clock analyses are intrinsically tied to these prior calibration points, hence improving calibrations will enable more precise divergence time estimations. Here we provide a review of previously described Precambrian microfossils, biomarkers and geochemical markers that inform upon the early evolution of cyanobacteria. Future research in micropalaeontology will require novel analyses and imaging techniques to improve taxonomic affiliation of many Precambrian microfossils. Consequently, a better understanding of early cyanobacterial evolution will not only allow for a more specific calibration of cyanobacterial and eubacterial phylogenies, but also provide new dates for the tree

  12. Musical emotions: Functions, origins, evolution

    Science.gov (United States)

    Perlovsky, Leonid

    2010-03-01

    Theories of music origins and the role of musical emotions in the mind are reviewed. Most existing theories contradict each other, and cannot explain mechanisms or roles of musical emotions in workings of the mind, nor evolutionary reasons for music origins. Music seems to be an enigma. Nevertheless, a synthesis of cognitive science and mathematical models of the mind has been proposed describing a fundamental role of music in the functioning and evolution of the mind, consciousness, and cultures. The review considers ancient theories of music as well as contemporary theories advanced by leading authors in this field. It addresses one hypothesis that promises to unify the field and proposes a theory of musical origin based on a fundamental role of music in cognition and evolution of consciousness and culture. We consider a split in the vocalizations of proto-humans into two types: one less emotional and more concretely-semantic, evolving into language, and the other preserving emotional connections along with semantic ambiguity, evolving into music. The proposed hypothesis departs from other theories in considering specific mechanisms of the mind-brain, which required the evolution of music parallel with the evolution of cultures and languages. Arguments are reviewed that the evolution of language toward becoming the semantically powerful tool of today required emancipation from emotional encumbrances. The opposite, no less powerful mechanisms required a compensatory evolution of music toward more differentiated and refined emotionality. The need for refined music in the process of cultural evolution is grounded in fundamental mechanisms of the mind. This is why today's human mind and cultures cannot exist without today's music. The reviewed hypothesis gives a basis for future analysis of why different evolutionary paths of languages were paralleled by different evolutionary paths of music. Approaches toward experimental verification of this hypothesis in

  13. Chromatin immunoprecipitation to analyze DNA binding sites of HMGA2.

    Directory of Open Access Journals (Sweden)

    Nina Winter

    Full Text Available BACKGROUND: HMGA2 is an architectonic transcription factor abundantly expressed during embryonic and fetal development and it is associated with the progression of malignant tumors. The protein harbours three basically charged DNA binding domains and an acidic protein binding C-terminal domain. DNA binding induces changes of DNA conformation and hence results in global overall change of gene expression patterns. Recently, using a PCR-based SELEX (Systematic Evolution of Ligands by Exponential Enrichment procedure two consensus sequences for HMGA2 binding have been identified. METHODOLOGY/PRINCIPAL FINDINGS: In this investigation chromatin immunoprecipitation (ChIP experiments and bioinformatic methods were used to analyze if these binding sequences can be verified on chromatin of living cells as well. CONCLUSION: After quantification of HMGA2 protein in different cell lines the colon cancer derived cell line HCT116 was chosen for further ChIP experiments because of its 3.4-fold higher HMGA2 protein level. 49 DNA fragments were obtained by ChIP. These fragments containing HMGA2 binding sites have been analyzed for their AT-content, location in the human genome and similarities to sequences generated by a SELEX study. The sequences show a significantly higher AT-content than the average of the human genome. The artificially generated SELEX sequences and short BLAST alignments (11 and 12 bp of the ChIP fragments from living cells show similarities in their organization. The flanking regions are AT-rich, whereas a lower conservation is present in the center of the sequences.

  14. Development of aptamers against unpurified proteins.

    Science.gov (United States)

    Goto, Shinichi; Tsukakoshi, Kaori; Ikebukuro, Kazunori

    2017-12-01

    SELEX (Systematic Evolution of Ligands by EXponential enrichment) has been widely used for the generation of aptamers against target proteins. However, its requirement for pure target proteins remains a major problem in aptamer selection, as procedures for protein purification from crude bio-samples are not only complicated but also time and labor consuming. This is because native proteins can be found in a large number of diverse forms because of posttranslational modifications and their complicated molecular conformations. Moreover, several proteins are difficult to purify owing to their chemical fragility and/or rarity in native samples. An alternative route is the use of recombinant proteins for aptamer selection, because they are homogenous and easily purified. However, aptamers generated against recombinant proteins produced in prokaryotic cells may not interact with the same proteins expressed in eukaryotic cells because of posttranslational modifications. Moreover, to date recombinant proteins have been constructed for only a fraction of proteins expressed in the human body. Therefore, the demand for advanced SELEX methods not relying on complicated purification processes from native samples or recombinant proteins is growing. This review article describes several such techniques that allow researchers to directly develop an aptamer from various unpurified samples, such as whole cells, tissues, serum, and cell lysates. The key advantages of advanced SELEX are that it does not require a purification process from a crude bio-sample, maintains the functional states of target proteins, and facilitates the development of aptamers against unidentified and uncharacterized proteins in unpurified biological samples. © 2017 Wiley Periodicals, Inc.

  15. In vitro Selection and Interaction Studies of a DNA Aptamer Targeting Protein A.

    Directory of Open Access Journals (Sweden)

    Regina Stoltenburg

    Full Text Available A new DNA aptamer targeting Protein A is presented. The aptamer was selected by use of the FluMag-SELEX procedure. The SELEX technology (Systematic Evolution of Ligands by EXponential enrichment is widely applied as an in vitro selection and amplification method to generate target-specific aptamers and exists in various modified variants. FluMag-SELEX is one of them and is characterized by the use of magnetic beads for target immobilization and fluorescently labeled oligonucleotides for monitoring the aptamer selection progress. Structural investigations and sequence truncation experiments of the selected aptamer for Protein A led to the conclusion, that a stem-loop structure at its 5'-end including the 5'-primer binding site is essential for aptamer-target binding. Extensive interaction analyses between aptamer and Protein A were performed by methods like surface plasmon resonance, MicroScale Thermophoresis and bead-based binding assays using fluorescence measurements. The binding of the aptamer to its target was thus investigated in assays with immobilization of one of the binding partners each, and with both binding partners in solution. Affinity constants were determined in the low micromolar to submicromolar range, increasing to the nanomolar range under the assumption of avidity. Protein A provides more than one binding site for the aptamer, which may overlap with the known binding sites for immunoglobulins. The aptamer binds specifically to both native and recombinant Protein A, but not to other immunoglobulin-binding proteins like Protein G and L. Cross specificity to other proteins was not found. The application of the aptamer is directed to Protein A detection or affinity purification. Moreover, whole cells of Staphylococcus aureus, presenting Protein A on the cell surface, could also be bound by the aptamer.

  16. In vitro Selection and Interaction Studies of a DNA Aptamer Targeting Protein A.

    Science.gov (United States)

    Stoltenburg, Regina; Schubert, Thomas; Strehlitz, Beate

    2015-01-01

    A new DNA aptamer targeting Protein A is presented. The aptamer was selected by use of the FluMag-SELEX procedure. The SELEX technology (Systematic Evolution of Ligands by EXponential enrichment) is widely applied as an in vitro selection and amplification method to generate target-specific aptamers and exists in various modified variants. FluMag-SELEX is one of them and is characterized by the use of magnetic beads for target immobilization and fluorescently labeled oligonucleotides for monitoring the aptamer selection progress. Structural investigations and sequence truncation experiments of the selected aptamer for Protein A led to the conclusion, that a stem-loop structure at its 5'-end including the 5'-primer binding site is essential for aptamer-target binding. Extensive interaction analyses between aptamer and Protein A were performed by methods like surface plasmon resonance, MicroScale Thermophoresis and bead-based binding assays using fluorescence measurements. The binding of the aptamer to its target was thus investigated in assays with immobilization of one of the binding partners each, and with both binding partners in solution. Affinity constants were determined in the low micromolar to submicromolar range, increasing to the nanomolar range under the assumption of avidity. Protein A provides more than one binding site for the aptamer, which may overlap with the known binding sites for immunoglobulins. The aptamer binds specifically to both native and recombinant Protein A, but not to other immunoglobulin-binding proteins like Protein G and L. Cross specificity to other proteins was not found. The application of the aptamer is directed to Protein A detection or affinity purification. Moreover, whole cells of Staphylococcus aureus, presenting Protein A on the cell surface, could also be bound by the aptamer.

  17. Facilitated variation: how evolution learns from past environments to generalize to new environments.

    Directory of Open Access Journals (Sweden)

    Merav Parter

    2008-11-01

    Full Text Available One of the striking features of evolution is the appearance of novel structures in organisms. Recently, Kirschner and Gerhart have integrated discoveries in evolution, genetics, and developmental biology to form a theory of facilitated variation (FV. The key observation is that organisms are designed such that random genetic changes are channeled in phenotypic directions that are potentially useful. An open question is how FV spontaneously emerges during evolution. Here, we address this by means of computer simulations of two well-studied model systems, logic circuits and RNA secondary structure. We find that evolution of FV is enhanced in environments that change from time to time in a systematic way: the varying environments are made of the same set of subgoals but in different combinations. We find that organisms that evolve under such varying goals not only remember their history but also generalize to future environments, exhibiting high adaptability to novel goals. Rapid adaptation is seen to goals composed of the same subgoals in novel combinations, and to goals where one of the subgoals was never seen in the history of the organism. The mechanisms for such enhanced generation of novelty (generalization are analyzed, as is the way that organisms store information in their genomes about their past environments. Elements of facilitated variation theory, such as weak regulatory linkage, modularity, and reduced pleiotropy of mutations, evolve spontaneously under these conditions. Thus, environments that change in a systematic, modular fashion seem to promote facilitated variation and allow evolution to generalize to novel conditions.

  18. Understanding Collateral Evolution in Linux Device Drivers

    DEFF Research Database (Denmark)

    Padioleau, Yoann; Lawall, Julia Laetitia; Muller, Gilles

    2006-01-01

    no tools to help in this process, collateral evolution is thus time consuming and error prone.In this paper, we present a qualitative and quantitative assessment of collateral evolution in Linux device driver code. We provide a taxonomy of evolutions and collateral evolutions, and use an automated patch......-analysis tool that we have developed to measure the number of evolutions and collateral evolutions that affect device drivers between Linux versions 2.2 and 2.6. In particular, we find that from one version of Linux to the next, collateral evolutions can account for up to 35% of the lines modified in such code....

  19. Teaching evolution (and all of biology) more effectively: Strategies for engagement, critical reasoning, and confronting misconceptions.

    Science.gov (United States)

    Nelson, Craig E

    2008-08-01

    The strength of the evidence supporting evolution has increased markedly since the discovery of DNA but, paradoxically, public resistance to accepting evolution seems to have become stronger. A key dilemma is that science faculty have often continued to teach evolution ineffectively, even as the evidence that traditional ways of teaching are inferior has become stronger and stronger. Three pedagogical strategies that together can make a large difference in students' understanding and acceptance of evolution are extensive use of interactive engagement, a focus on critical thinking in science (especially on comparisons and explicit criteria) and using both of these in helping the students actively compare their initial conceptions (and publicly popular misconceptions) with more fully scientific conceptions. The conclusion that students' misconceptions must be dealt with systematically can be difficult for faculty who are teaching evolution since much of the students' resistance is framed in religious terms and one might be reluctant to address religious ideas in class. Applications to teaching evolution are illustrated with examples that address criteria and critical thinking, standard geology versus flood geology, evolutionary developmental biology versus organs of extreme perfection, and the importance of using humans as a central example. It is also helpful to bridge the false dichotomy, seen by many students, between atheistic evolution versus religious creationism. These applications are developed in detail and are intended to be sufficient to allow others to use these approaches in their teaching. Students and other faculty were quite supportive of these approaches as implemented in my classes.

  20. WORKING ON THE RAILROAD: WORKERS AND THE EVOLUTION OF THE PENNSYLVANIA RAILROAD’S PENSION PLAN

    Directory of Open Access Journals (Sweden)

    Charles W. Cheape

    2007-01-01

    Full Text Available In 1900 the Pennsylvania Railroad Company implemented a pioneering pension plan that became a model for American business in the twentieth century. Although scholars have described the two-stage creation as management’s effort to achieve corporate efficiency and control over its labor force, this paper demonstrates a more complicated, untidy evolution. Employees played a vital, active role in the quarter-century development of the pension scheme, repeatedly shaping the process and its results directly and indirectly, consciously and unconsciously. Furthermore, the plan’s evolution was a messy, often decentralized, and incremental process considerably at oddsw ith the firm’s reputation for systematic, analytical management.

  1. Helicity evolution at small x

    International Nuclear Information System (INIS)

    Kovchegov, Yuri V.; Pitonyak, Daniel; Sievert, Matthew D.

    2016-01-01

    We construct small-x evolution equations which can be used to calculate quark and anti-quark helicity TMDs and PDFs, along with the g 1 structure function. These evolution equations resum powers of α s ln 2  (1/x) in the polarization-dependent evolution along with the powers of α s ln (1/x) in the unpolarized evolution which includes saturation effects. The equations are written in an operator form in terms of polarization-dependent Wilson line-like operators. While the equations do not close in general, they become closed and self-contained systems of non-linear equations in the large-N c and large-N c   N f limits. As a cross-check, in the ladder approximation, our equations map onto the same ladder limit of the infrared evolution equations for the g 1 structure function derived previously by Bartels, Ermolaev and Ryskin http://dx.doi.org/10.1007/s002880050285.

  2. Experimental evolution in biofilm populations

    Science.gov (United States)

    Steenackers, Hans P.; Parijs, Ilse; Foster, Kevin R.; Vanderleyden, Jozef

    2016-01-01

    Biofilms are a major form of microbial life in which cells form dense surface associated communities that can persist for many generations. The long-life of biofilm communities means that they can be strongly shaped by evolutionary processes. Here, we review the experimental study of evolution in biofilm communities. We first provide an overview of the different experimental models used to study biofilm evolution and their associated advantages and disadvantages. We then illustrate the vast amount of diversification observed during biofilm evolution, and we discuss (i) potential ecological and evolutionary processes behind the observed diversification, (ii) recent insights into the genetics of adaptive diversification, (iii) the striking degree of parallelism between evolution experiments and real-life biofilms and (iv) potential consequences of diversification. In the second part, we discuss the insights provided by evolution experiments in how biofilm growth and structure can promote cooperative phenotypes. Overall, our analysis points to an important role of biofilm diversification and cooperation in bacterial survival and productivity. Deeper understanding of both processes is of key importance to design improved antimicrobial strategies and diagnostic techniques. PMID:26895713

  3. The evolution of mollusc shells.

    Science.gov (United States)

    McDougall, Carmel; Degnan, Bernard M

    2018-05-01

    Molluscan shells are externally fabricated by specialized epithelial cells on the dorsal mantle. Although a conserved set of regulatory genes appears to underlie specification of mantle progenitor cells, the genes that contribute to the formation of the mature shell are incredibly diverse. Recent comparative analyses of mantle transcriptomes and shell proteomes of gastropods and bivalves are consistent with shell diversity being underpinned by a rapidly evolving mantle secretome (suite of genes expressed in the mantle that encode secreted proteins) that is the product of (a) high rates of gene co-option into and loss from the mantle gene regulatory network, and (b) the rapid evolution of coding sequences, particular those encoding repetitive low complexity domains. Outside a few conserved genes, such as carbonic anhydrase, a so-called "biomineralization toolkit" has yet to be discovered. Despite this, a common suite of protein domains, which are often associated with the extracellular matrix and immunity, appear to have been independently and often uniquely co-opted into the mantle secretomes of different species. The evolvability of the mantle secretome provides a molecular explanation for the evolution and diversity of molluscan shells. These genomic processes are likely to underlie the evolution of other animal biominerals, including coral and echinoderm skeletons. This article is categorized under: Comparative Development and Evolution > Regulation of Organ Diversity Comparative Development and Evolution > Evolutionary Novelties. © 2018 Wiley Periodicals, Inc.

  4. Chaos and unpredictability in evolution.

    Science.gov (United States)

    Doebeli, Michael; Ispolatov, Iaroslav

    2014-05-01

    The possibility of complicated dynamic behavior driven by nonlinear feedbacks in dynamical systems has revolutionized science in the latter part of the last century. Yet despite examples of complicated frequency dynamics, the possibility of long-term evolutionary chaos is rarely considered. The concept of "survival of the fittest" is central to much evolutionary thinking and embodies a perspective of evolution as a directional optimization process exhibiting simple, predictable dynamics. This perspective is adequate for simple scenarios, when frequency-independent selection acts on scalar phenotypes. However, in most organisms many phenotypic properties combine in complicated ways to determine ecological interactions, and hence frequency-dependent selection. Therefore, it is natural to consider models for evolutionary dynamics generated by frequency-dependent selection acting simultaneously on many different phenotypes. Here we show that complicated, chaotic dynamics of long-term evolutionary trajectories in phenotype space is very common in a large class of such models when the dimension of phenotype space is large, and when there are selective interactions between the phenotypic components. Our results suggest that the perspective of evolution as a process with simple, predictable dynamics covers only a small fragment of long-term evolution. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  5. [Recovery: systematic review of a concept].

    Science.gov (United States)

    Baccari, Ivana Oliveira Preto; Campos, Rosana Teresa Onocko; Stefanello, Sabrina

    2015-01-01

    The concept of recovery has been described in papers as a state of psychic, physical and social recuperation of day-to-day functions. The scope of this article is to analyze the concepts of the term in different research methodologies and the paradigmatic evolution of the recovery concept. Systematic bibliographical research was conducted in the Pubmed database using the words "recovery + schizophrenia" limited to freely available full papers published in the previous two years. Nineteen papers were analyzed. The majority of the papers sought associations between characteristic data and recovery; few papers discussed the concept in a way to distinguish it from other words like cure or rehabilitation. Recovery as a state in which people with severe mental illness can feel like the creators of their own itinerary tend to be found in qualitative studies and in bibliographic reviews in which the meaning of recovery is not related to the lack of symptoms and tends to prioritize how participative the life of an individual can be despite the disease. Some quantitative studies detect this conceptual difference. In qualitative research there is an increase in the concept of recovery and in ways of promoting it.

  6. Systematics of stalked jellyfishes (Cnidaria: Staurozoa

    Directory of Open Access Journals (Sweden)

    Lucília S. Miranda

    2016-05-01

    Full Text Available Staurozoan classification is highly subjective, based on phylogeny-free inferences, and suborders, families, and genera are commonly defined by homoplasies. Additionally, many characters used in the taxonomy of the group have ontogenetic and intraspecific variation, and demand new and consistent assessments to establish their correct homologies. Consequently, Staurozoa is in need of a thorough systematic revision. The aim of this study is to propose a comprehensive phylogenetic hypothesis for Staurozoa, providing the first phylogenetic classification for the group. According to our working hypothesis based on a combined set of molecular data (mitochondrial markers COI and 16S, and nuclear markers ITS, 18S, and 28S, the traditional suborders Cleistocarpida (animals with claustrum and Eleutherocarpida (animals without claustrum are not monophyletic. Instead, our results show that staurozoans are divided into two groups, herein named Amyostaurida and Myostaurida, which can be distinguished by the absence/presence of interradial longitudinal muscles in the peduncle, respectively. We propose a taxonomic revision at the family and genus levels that preserves the monophyly of taxa. We provide a key for staurozoan genera and discuss the evolution of the main characters used in staurozoan taxonomy.

  7. A new paradigma on the plant evolution: from a natural evolution to an artificial evolution?

    Science.gov (United States)

    Bennici, Andrea

    2005-01-01

    After evidencing the great importance of plants for animals and humans in consequence of the photosynthesis, several considerations on plant evolution are made. One of the peculiar characteristics of the plant is the sessile property, due especially to the cell wall. This factor, principally, strengthened by the photosynthetic process, determined the particular developmental pattern of the plant, which is characterized by the continuous formation of new organs. The plant immobility, although negative for its survival, has been, in great part, overcome by the acquisition of the capacity of adaptation (plasticity) to the environmental stresses and changes, and the establishment of more adapted genotypes. This capacity to react to the external signals induced Trewavas to speak of "plant intelligence". The plant movement incapacity and the evolution of the sexual reproduction system were strongly correlated. In this context, the evolution of the flower in the Angiosperms has been particularly important to allow the male gamete to fertilize the immobile female gamete. Moreover, the formation of fruit and seed greatly improved the dispersal and conservation of the progeny in the environment. With the flower, mechanisms to favour the outcrossing among different individuals appeared, which are essential to increase the genetic variability and, then, the plant evolution itself. Although the Angiosperms seem highly evolved, the plant evolution is not surely finished, because many reported morpho-physiological processes may be still considered susceptible of further improvement. In the last years the relationships among humans, plants and environment are becoming closer and closer. This is due to the use of the DNA recombinant techniques with the aim to modify artificially plant characters. Therefore, the risk of a plant evolution strongly directed towards practical or commercial objectives, or "an artificial evolution", may be hypothesized.

  8. [A accurate identification method for Chinese materia medica--systematic identification of Chinese materia medica].

    Science.gov (United States)

    Wang, Xue-Yong; Liao, Cai-Li; Liu, Si-Qi; Liu, Chun-Sheng; Shao, Ai-Juan; Huang, Lu-Qi

    2013-05-01

    This paper put forward a more accurate identification method for identification of Chinese materia medica (CMM), the systematic identification of Chinese materia medica (SICMM) , which might solve difficulties in CMM identification used the ordinary traditional ways. Concepts, mechanisms and methods of SICMM were systematically introduced and possibility was proved by experiments. The establishment of SICMM will solve problems in identification of Chinese materia medica not only in phenotypic characters like the mnorphous, microstructure, chemical constituents, but also further discovery evolution and classification of species, subspecies and population in medical plants. The establishment of SICMM will improve the development of identification of CMM and create a more extensive study space.

  9. Extinction Events Can Accelerate Evolution

    DEFF Research Database (Denmark)

    Lehman, Joel; Miikkulainen, Risto

    2015-01-01

    Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate...... evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending...... computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific...

  10. Evolution of the Cosmic Web

    Science.gov (United States)

    Einasto, J.

    2017-07-01

    In the evolution of the cosmic web dark energy plays an important role. To understand the role of dark energy we investigate the evolution of superclusters in four cosmological models: standard model SCDM, conventional model LCDM, open model OCDM, and a hyper-dark-energy model HCDM. Numerical simulations of the evolution are performed in a box of size 1024 Mpc/h. Model superclusters are compared with superclusters found for Sloan Digital Sky Survey (SDSS). Superclusters are searched using density fields. LCDM superclusters have properties, very close to properties of observed SDSS superclusters. Standard model SCDM has about 2 times more superclusters than other models, but SCDM superclusters are smaller and have lower luminosities. Superclusters as principal structural elements of the cosmic web are present at all cosmological epochs.

  11. Evolution equations for Killing fields

    International Nuclear Information System (INIS)

    Coll, B.

    1977-01-01

    The problem of finding necessary and sufficient conditions on the Cauchy data for Einstein equations which insure the existence of Killing fields in a neighborhood of an initial hypersurface has been considered recently by Berezdivin, Coll, and Moncrief. Nevertheless, it can be shown that the evolution equations obtained in all these cases are of nonstrictly hyperbolic type, and, thus, the Cauchy data must belong to a special class of functions. We prove here that, for the vacuum and Einstein--Maxwell space--times and in a coordinate independent way, one can always choose, as evolution equations for the Killing fields, a strictly hyperbolic system: The above theorems can be thus extended to all Cauchy data for which the Einstein evolution problem has been proved to be well set

  12. Modelling microstructural evolution under irradiation

    International Nuclear Information System (INIS)

    Tikare, V.

    2015-01-01

    Microstructural evolution of materials under irradiation is characterised by some unique features that are not typically present in other application environments. While much understanding has been achieved by experimental studies, the ability to model this microstructural evolution for complex materials states and environmental conditions not only enhances understanding, it also enables prediction of materials behaviour under conditions that are difficult to duplicate experimentally. Furthermore, reliable models enable designing materials for improved engineering performance for their respective applications. Thus, development and application of mesoscale microstructural model are important for advancing nuclear materials technologies. In this chapter, the application of the Potts model to nuclear materials will be reviewed and demonstrated, as an example of microstructural evolution processes. (author)

  13. The evolution of the elements

    International Nuclear Information System (INIS)

    Williams, P.M.

    1978-01-01

    It is believed that only the lightest elements, hydrogen and helium, were created during the 'Big Bang' origin of the Universe and that all heavier elements were synthesized by nuclear reactions in stars, the interstellar medium and possibly in 'little bangs' in the nuclei of galaxies. The composition of the interstellar medium has evolved through enrichment by processed material shed by evolving stars and the composition of the Solar System reflects that of the interstellar medium at the time of its formation. Differentiation processes during the evolution of the Solar System and individual planets account for the different compositions of the Sun and the planets. The measurement of the abundance distribution of the elements has become a very powerful tool in the elucidation of the evolution of the Solar System, stars and the Galaxy. This review attempts to trace the formation of the elements in stars and their subsequent evolution. (author)

  14. Darwinian evolution on a chip.

    Directory of Open Access Journals (Sweden)

    Brian M Paegel

    2008-04-01

    Full Text Available Computer control of Darwinian evolution has been demonstrated by propagating a population of RNA enzymes in a microfluidic device. The RNA population was challenged to catalyze the ligation of an oligonucleotide substrate under conditions of progressively lower substrate concentrations. A microchip-based serial dilution circuit automated an exponential growth phase followed by a 10-fold dilution, which was repeated for 500 log-growth iterations. Evolution was observed in real time as the population adapted and achieved progressively faster growth rates over time. The final evolved enzyme contained a set of 11 mutations that conferred a 90-fold improvement in substrate utilization, coinciding with the applied selective pressure. This system reduces evolution to a microfluidic algorithm, allowing the experimenter to observe and manipulate adaptation.

  15. Institutional Evolution and Corporate Boards

    DEFF Research Database (Denmark)

    Chen, Victor Zitian; Hobdari, Bersant; Sun, Pei

    2014-01-01

    We argue that corporate boards are a dynamic repository of human- and social capital in response to external institutional evolution. Theoretically, integrating institutional economics, agency theory and resource dependence theory, we explain that evolution of market-, legal- and political......, since the board changes are typically proposed by the block shareholders, whose motivation for doing so is closely associated with a corporation’s financial performance, we further argue that financial performance is a key moderator of the relationships between institutional evolution and changes...... institutions restructures the particular context in which board members play their two primary roles: monitoring the CEO on behalf of the shareholders, suggested by the agency theory, and supporting the CEO by providing resources, knowledge and information, suggested by the resource dependence theory...

  16. Time evolution of gamma rays from supernova remnants

    Science.gov (United States)

    Gaggero, Daniele; Zandanel, Fabio; Cristofari, Pierre; Gabici, Stefano

    2018-04-01

    We present a systematic phenomenological study focused on the time evolution of the non-thermal radiation - from radio waves to gamma rays - emitted by typical supernova remnants via hadronic and leptonic mechanisms, for two classes of progenitors: thermonuclear and core-collapse. To this aim, we develop a numerical tool designed to model the evolution of the cosmic ray spectrum inside a supernova remnant, and compute the associated multi-wavelength emission. We demonstrate the potential of this tool in the context of future population studies based on large collection of high-energy gamma-ray data. We discuss and explore the relevant parameter space involved in the problem, and focus in particular on their impact on the maximum energy of accelerated particles, in order to study the effectiveness and duration of the PeVatron phase. We outline the crucial role of the ambient medium through which the shock propagates during the remnant evolution. In particular, we point out the role of dense clumps in creating a significant hardening in the hadronic gamma-ray spectrum.

  17. Synthesis and textural evolution of alumina particles with mesoporous structures

    International Nuclear Information System (INIS)

    Liu Xun; Peng Tianyou; Yao Jinchun; Lv Hongjin; Huang Cheng

    2010-01-01

    Alumina particles with mesostructures were synthesized through a chemical precipitation method by using different inorganic aluminum salts followed by a heterogeneous azeotropic distillation and calcination process. The obtained mesoporous γ-alumina particles were systematically characterized by the X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption measurement. Effects of the aluminum salt counter anion, pH value and the azeotropic distillation process on the structural or textural evolution of alumina particles were investigated. It is found that Cl - in the reaction solution can restrain the textural evolution of the resultant precipitates into two-dimensional crystallized pseudoboehmite lamellae during the heterogeneous azeotropic distillation, and then transformed into γ-Al 2 O 3 particles with mesostructures after further calcination at 1173 K, whereas coexisting SO 4 2- can promote above morphology evolution and then transformed into γ-Al 2 O 3 nanofibers after calcination at 1173 K. Moreover nearly all materials retain relatively high specific surface areas larger than 100 m 2 g -1 even after calcinations at 1173 K. - Graphical abstract: Co-existing Cl - is beneficial for the formation of γ-alumina nanoparticles with mesostructures during the precipitation process. Interparticle and intraparticle mesopores can be derived from acidic solution and near neutral solution, respectively.

  18. Synthesis and textural evolution of alumina particles with mesoporous structures

    Science.gov (United States)

    Liu, Xun; Peng, Tianyou; Yao, Jinchun; Lv, Hongjin; Huang, Cheng

    2010-06-01

    Alumina particles with mesostructures were synthesized through a chemical precipitation method by using different inorganic aluminum salts followed by a heterogeneous azeotropic distillation and calcination process. The obtained mesoporous γ-alumina particles were systematically characterized by the X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption measurement. Effects of the aluminum salt counter anion, pH value and the azeotropic distillation process on the structural or textural evolution of alumina particles were investigated. It is found that Cl - in the reaction solution can restrain the textural evolution of the resultant precipitates into two-dimensional crystallized pseudoboehmite lamellae during the heterogeneous azeotropic distillation, and then transformed into γ-Al 2O 3 particles with mesostructures after further calcination at 1173 K, whereas coexisting SO 42- can promote above morphology evolution and then transformed into γ-Al 2O 3 nanofibers after calcination at 1173 K. Moreover nearly all materials retain relatively high specific surface areas larger than 100 m 2 g -1 even after calcinations at 1173 K.

  19. Evolution of facial color pattern complexity in lemurs.

    Science.gov (United States)

    Rakotonirina, Hanitriniaina; Kappeler, Peter M; Fichtel, Claudia

    2017-11-09

    Interspecific variation in facial color patterns across New and Old World primates has been linked to species recognition and group size. Because group size has opposite effects on interspecific variation in facial color patterns in these two radiations, a study of the third large primate radiation may shed light on convergences and divergences in this context. We therefore compiled published social and ecological data and analyzed facial photographs of 65 lemur species to categorize variation in hair length, hair and skin coloration as well as color brightness. Phylogenetically controlled analyses revealed that group size and the number of sympatric species did not influence the evolution of facial color complexity in lemurs. Climatic factors, however, influenced facial color complexity, pigmentation and hair length in a few facial regions. Hair length in two facial regions was also correlated with group size and may facilitate individual recognition. Since phylogenetic signals were moderate to high for most models, genetic drift may have also played a role in the evolution of facial color patterns of lemurs. In conclusion, social factors seem to have played only a subordinate role in the evolution of facial color complexity in lemurs, and, more generally, group size appears to have no systematic functional effect on facial color complexity across all primates.

  20. Quality of systematic reviews in pediatric oncology--a systematic review.

    Science.gov (United States)

    Lundh, Andreas; Knijnenburg, Sebastiaan L; Jørgensen, Anders W; van Dalen, Elvira C; Kremer, Leontien C M

    2009-12-01

    To ensure evidence-based decision making in pediatric oncology systematic reviews are necessary. The objective of our study was to evaluate the methodological quality of all currently existing systematic reviews in pediatric oncology. We identified eligible systematic reviews through a systematic search of the literature. Data on clinical and methodological characteristics of the included systematic reviews were extracted. The methodological quality of the included systematic reviews was assessed using the overview quality assessment questionnaire, a validated 10-item quality assessment tool. We compared the methodological quality of systematic reviews published in regular journals with that of Cochrane systematic reviews. We included 117 systematic reviews, 99 systematic reviews published in regular journals and 18 Cochrane systematic reviews. The average methodological quality of systematic reviews was low for all ten items, but the quality of Cochrane systematic reviews was significantly higher than systematic reviews published in regular journals. On a 1-7 scale, the median overall quality score for all systematic reviews was 2 (range 1-7), with a score of 1 (range 1-7) for systematic reviews in regular journals compared to 6 (range 3-7) in Cochrane systematic reviews (pmethodological flaws leading to a high risk of bias. While Cochrane systematic reviews were of higher methodological quality than systematic reviews in regular journals, some of them also had methodological problems. Therefore, the methodology of each individual systematic review should be scrutinized before accepting its results.

  1. Online evolution of robot behaviour

    OpenAIRE

    Silva, Fernando Goulart da

    2012-01-01

    Tese de mestrado em Engenharia Informática (Interação e Conhecimento), apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2012 In this dissertation, we propose and evaluate two novel approaches to the online synthesis of neural controllers for autonomous robots. The first approach is odNEAT, an online, distributed, and decentralized version of NeuroEvolution of Augmenting Topologies (NEAT). odNEAT is an algorithm for online evolution in groups of embodied agents such a...

  2. Evolution in close binary systems

    International Nuclear Information System (INIS)

    Yungel'son, L.R.; Masevich, A.G.

    1983-01-01

    Duality is the property most typical of stars. If one investigates how prevalent double stars are, making due allowance for selection effects, one finds that as many as 90 percent of all stars are paired. Contrary to tradition it is single stars that are out of the ordinary, and as will be shown presently even some of these may have been formed by coalescence of the members of binary systems. This review deals with the evolution of close binaries, defined as double-star systems whose evolution entails exchange of material between the two components

  3. Entanglement and inhibited quantum evolution

    Energy Technology Data Exchange (ETDEWEB)

    Toschek, P E; Balzer, Chr; Hannemann, Th; Wunderlich, Ch; Neuhauser, W [Universitaet Hamburg, Institut fuer Laser-Physik, Jungiusstrasse 9, D-20355 Hamburg (Germany)

    2003-03-14

    The evolution of a quantum system is impeded by the system's state being observed. A test on an ensemble neither proves the causal nexus nor discloses the nature of the inhibition. Two recent experiments that make use of sequential optical or microwave-optical double resonance on an individual trapped ion disprove a dynamical effect of back action by meter or environment. They rather indicate the ionic states involved in the evolution being entangled with the potentially recorded bivalued scattered-light signal.

  4. Explaining the Evolution of Poverty

    DEFF Research Database (Denmark)

    Arndt, Channing; Hussain, Azhar; Jones, Edward Samuel

    2012-01-01

    We provide a comprehensive approach for analyzing the evolution of poverty using Mozambique as a case study. Bringing together data from disparate sources, we develop a novel “back-casting” framework that links a dynamic computable general equilibrium model to a micro-simulation poverty module....... This framework provides a new approach to explaining and decomposing the evolution of poverty, as well as to examining rigorously the coherence between poverty, economic growth, and inequality outcomes. Finally, various simple but useful and rarely-applied approaches to considering regional changes in poverty...

  5. Experimental evolution of E. coli

    Science.gov (United States)

    Zhang, Mengshi

    The evolution from unicellular to multicellular behavior is an essential step in the history of life. Our aim is to investigate the emergence of collective behavior in the model organism Escherichia coli (E. coli) and its selection advantages, such as better utilization of public goods. Our preliminary results suggest that the evolution of collective behavior may be a natural response to stressed conditions. Mailing address: Room 306 Science Centre North Block, The Chinese University of Hong Kong, Shatin, N.T. Hong Kong SAR. Phone: +852-3943-6354. Fax: +852-2603-5204. E-mail: mengshi0928@gmail.com.

  6. Systematic investigation of lard polymorphism using combined DSC and time-resolved synchrotron X-ray diffraction

    NARCIS (Netherlands)

    Kalnin, D.J.E.; Lesieur, P.; Artzner, F.; Keller, G.; Ollivon, M.

    2005-01-01

    The polymorphic behavior of lard was systematically investigated by differential scanning calorimetry (DSC) while simultaneously monitoring the formation of the different crystal forms with X-ray diffraction (XRDT). To interpret the complex polymorphic evolution of the sample analyzed by regular

  7. Statistical and physical evolution of QSO's

    International Nuclear Information System (INIS)

    Caditz, D.; Petrosian, V.

    1989-09-01

    The relationship between the physical evolution of discrete extragalactic sources, the statistical evolution of the observed population of sources, and the cosmological model is discussed. Three simple forms of statistical evolution: pure luminosity evolution (PLE), pure density evolution (PDE), and generalized luminosity evolution (GLE), are considered in detail together with what these forms imply about the physical evolution of individual sources. Two methods are used to analyze the statistical evolution of the observed distribution of QSO's (quasars) from combined flux limited samples. It is shown that both PLE and PDE are inconsistent with the data over the redshift range 0 less than z less than 2.2, and that a more complicated form of evolution such as GLE is required, independent of the cosmological model. This result is important for physical models of AGN, and in particular, for the accretion disk model which recent results show may be inconsistent with PLE

  8. Student Teachers' Approaches to Teaching Biological Evolution

    Science.gov (United States)

    Borgerding, Lisa A.; Klein, Vanessa A.; Ghosh, Rajlakshmi; Eibel, Albert

    2015-06-01

    Evolution is fundamental to biology and scientific literacy, but teaching high school evolution is often difficult. Evolution teachers face several challenges including limited content knowledge, personal conflicts with evolution, expectations of resistance, concerns about students' conflicts with religion, and curricular constraints. Evolution teaching can be particularly challenging for student teachers who are just beginning to gain pedagogical knowledge and pedagogical content knowledge related to evolution teaching and who seek approval from university supervisors and cooperating teachers. Science teacher educators need to know how to best support student teachers as they broach the sometimes daunting task of teaching evolution within student teaching placements. This multiple case study report documents how three student teachers approached evolution instruction and what influenced their approaches. Data sources included student teacher interviews, field note observations for 4-5 days of evolution instruction, and evolution instructional artifacts. Data were analyzed using grounded theory approaches to develop individual cases and a cross-case analysis. Seven influences (state exams and standards, cooperating teacher, ideas about teaching and learning, concerns about evolution controversy, personal commitment to evolution, knowledge and preparation for teaching evolution, and own evolution learning experiences) were identified and compared across cases. Implications for science teacher preparation and future research are provided.

  9. Activity and stability trends of perovskite oxides for oxygen evolution catalysis at neutral pH

    OpenAIRE

    Ling, Chen; Jia, Hongfei; Han, Binghong; Risch, Marcel; Lee, Yueh Lin; Shao-Horn, Yang

    2015-01-01

    Perovskite oxides (ABO[subscript 3]) have been studied extensively to promote the kinetics of the oxygen evolution reaction (OER) in alkaline electrolytes. However, developing highly active catalysts for OER at near-neutral pH is desirable for many photoelectrochemical/electrochemical devices. In this paper, we systematically studied the activity and stability of well-known perovskite oxides for OER at pH 7. Previous activity descriptors established for perovskite oxides at pH 13, such as hav...

  10. Evolution of energy conversion plants

    International Nuclear Information System (INIS)

    Osnaghi, C.

    2001-01-01

    The paper concerns the evolution and the future development of energy conversion plants and puts into evidence the great importance of the scientific and technological improvement in machines design, in order to optimize the use of energy resources and to improve ambient compatibility [it

  11. Time evolution in quantum cosmology

    International Nuclear Information System (INIS)

    Lawrie, Ian D.

    2011-01-01

    A commonly adopted relational account of time evolution in generally covariant systems, and more specifically in quantum cosmology, is argued to be unsatisfactory, insofar as it describes evolution relative to observed readings of a clock that does not exist as a bona fide observable object. A modified strategy is proposed, in which evolution relative to the proper time that elapses along the worldline of a specific observer can be described through the introduction of a ''test clock,'' regarded as internal to, and hence unobservable by, that observer. This strategy is worked out in detail in the case of a homogeneous cosmology, in the context of both a conventional Schroedinger quantization scheme, and a 'polymer' quantization scheme of the kind inspired by loop quantum gravity. Particular attention is given to limitations placed on the observability of time evolution by the requirement that a test clock should contribute only a negligible energy to the Hamiltonian constraint. It is found that suitable compromises are available, in which the clock energy is reasonably small, while Dirac observables are reasonably sharply defined.

  12. Adaptive evolution in ecological communities.

    Directory of Open Access Journals (Sweden)

    Martin M Turcotte

    Full Text Available Understanding how natural selection drives evolution is a key challenge in evolutionary biology. Most studies of adaptation focus on how a single environmental factor, such as increased temperature, affects evolution within a single species. The biological relevance of these experiments is limited because nature is infinitely more complex. Most species are embedded within communities containing many species that interact with one another and the physical environment. To understand the evolutionary significance of such ecological complexity, experiments must test the evolutionary impact of interactions among multiple species during adaptation. Here we highlight an experiment that manipulates species composition and tracks evolutionary responses within each species, while testing for the mechanisms by which species interact and adapt to their environment. We also discuss limitations of previous studies of adaptive evolution and emphasize how an experimental evolution approach can circumvent such shortcomings. Understanding how community composition acts as a selective force will improve our ability to predict how species adapt to natural and human-induced environmental change.

  13. Temperature evolution during dissipative collapse

    Indian Academy of Sciences (India)

    Abstract. We investigate the gravitational collapse of a radiating sphere evolving into a final static configuration described by the interior Schwarzschild solution. The temperature profiles of this par- ticular model are obtained within the framework of causal thermodynamics. The overall temperature evolution is enhanced by ...

  14. The evolution of tensor polarization

    International Nuclear Information System (INIS)

    Huang, H.; Lee, S.Y.; Ratner, L.

    1993-01-01

    By using the equation of motion for the vector polarization, the spin transfer matrix for spin tensor polarization, the spin transfer matrix for spin tensor polarization is derived. The evolution equation for the tensor polarization is studied in the presence of an isolate spin resonance and in the presence of a spin rotor, or snake

  15. Evolution of planetary nebula nuclei

    International Nuclear Information System (INIS)

    Shaw, R.A.

    1985-01-01

    The evolution of planetary nebula nuclei (PNNs) is examined with the aid of the most recent available stellar evolution calculations and new observations of these objects. Their expected distribution in the log L-log T plane is calculated based upon the stellar evolutionary models of Paczynski, Schoenberner and Iben, the initial mass function derived by Miller and Scalo, and various assumptions concerning mass loss during post-main sequence evolution. The distribution is found to be insensitive both to the assumed range of main-sequence progenitor mass and to reasonable variations in the age and the star forming history of the galactic disk. Rather, the distribution is determined by the strong dependence of the rate of stellar evolution upon core mass, the steepness of the initial mass function, and to a lesser extent the finite lifetime of an observable planetary nebula. The theoretical distributions are rather different than any of those inferred from earlier observations. Possible observational selection effects that may be responsible are examined, as well as the intrinsic uncertainties associated with the theoretical model predictions. An extensive photometric and smaller photographic survey of southern hemisphere planetary nebulae (PNs) is presented

  16. Nonlocal higher order evolution equations

    KAUST Repository

    Rossi, Julio D.; Schö nlieb, Carola-Bibiane

    2010-01-01

    In this article, we study the asymptotic behaviour of solutions to the nonlocal operator ut(x, t)1/4(-1)n-1 (J*Id -1)n (u(x, t)), x ∈ ℝN, which is the nonlocal analogous to the higher order local evolution equation vt(-1)n-1(Δ)nv. We prove

  17. Topology evolution in macromolecular networks

    NARCIS (Netherlands)

    Kryven, I.

    2014-01-01

    Governed by various intermolecular forces, molecular networks tend to evolve from simple to very complex formations that have random structure. This randomness in the connectivity of the basic units can still be captured employing distributional description of the state of the system; the evolution

  18. Evolution of Karyotypes in Chameleons

    Czech Academy of Sciences Publication Activity Database

    Rovatsos, M.; Altmanová, M.; Johnson Pokorná, Martina; Velenský, P.; Baca, A. S.; Kratochvíl, L.

    2017-01-01

    Roč. 8, č. 12 (2017), č. článku 382. ISSN 2073-4425 Institutional support: RVO:67985904 Keywords : karyotype evolution * ITS * rDNA Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 3.600, year: 2016

  19. The Evolution of Scientific Knowledge

    DEFF Research Database (Denmark)

    Jensen, Hans Siggaard; Ricard, Lykke Margot; Vendelø, Morten Thanning

    The Evolution of Scientific Knowledge aims to reach a unique understanding of science with the help of economic and sociological theories. They use institutional and evolutionary theories and the sociological theories draw from the type of work on social studies of science that have, in recent...

  20. The Semiosic Evolution of Education

    Science.gov (United States)

    Olteanu, Alin

    2014-01-01

    The recent development of biosemiotics has revealed the achievement of knowledge and the development of science to be the results of the semiosis of all life forms, including those commonly regarded as cultural constructs. Education is thus a semiosic structure to which evolution itself has adapted, while learning is the semiotic phenomenon that…

  1. The evolution of nuclear regulation

    International Nuclear Information System (INIS)

    Martin, A.

    1997-01-01

    The already not so young history of nuclear regulations shows patterns and specific causes that have characterized and influenced its own evolution as well as the industry itself. Today's regulation is facing relevant challenges with potential significant effects. The quest for higher regulatory efficiency brings up the increasing need to base future actions on firmly established strategies. (Author) 7 refs

  2. Evolution of Deeply Embedded Protostars

    DEFF Research Database (Denmark)

    Frimann, Søren

    consequences for the evolution of protostellar systems. The sublimation of CO-ice from dust grains in the surrounding envelope can be used to trace accretion variability in protostars, because the increased heating during an accretion burst will cause the CO-ice to sublimate into the gas-phase where the excess...

  3. Adaptive evolution of molecular phenotypes

    International Nuclear Information System (INIS)

    Held, Torsten; Nourmohammad, Armita; Lässig, Michael

    2014-01-01

    Molecular phenotypes link genomic information with organismic functions, fitness, and evolution. Quantitative traits are complex phenotypes that depend on multiple genomic loci. In this paper, we study the adaptive evolution of a quantitative trait under time-dependent selection, which arises from environmental changes or through fitness interactions with other co-evolving phenotypes. We analyze a model of trait evolution under mutations and genetic drift in a single-peak fitness seascape. The fitness peak performs a constrained random walk in the trait amplitude, which determines the time-dependent trait optimum in a given population. We derive analytical expressions for the distribution of the time-dependent trait divergence between populations and of the trait diversity within populations. Based on this solution, we develop a method to infer adaptive evolution of quantitative traits. Specifically, we show that the ratio of the average trait divergence and the diversity is a universal function of evolutionary time, which predicts the stabilizing strength and the driving rate of the fitness seascape. From an information-theoretic point of view, this function measures the macro-evolutionary entropy in a population ensemble, which determines the predictability of the evolutionary process. Our solution also quantifies two key characteristics of adapting populations: the cumulative fitness flux, which measures the total amount of adaptation, and the adaptive load, which is the fitness cost due to a population's lag behind the fitness peak. (paper)

  4. The Evolution of Learning Mechanisms.

    Science.gov (United States)

    Garcia, John; Garcia y Robertson, Rodrigo

    This paper introduces seven principles of learning, enduring over the last five centuries of psychological thought, to discuss the evolution of the "Biophyche" (the brain in action) in the development of humans and other large organisms. It describes the conditioning theories of Darwin, Pavlov, and Thorndike and critically reviews the…

  5. Gas Evolution in Protoplanetary Disks

    NARCIS (Netherlands)

    Woitke, Peter; Dent, Bill; Thi, Wing-Fai; Sibthorpe, Bruce; Rice, Ken; Williams, Jonathan; Sicilia-Aguilar, Aurora; Brown, Joanna; Kamp, Inga; Pascucci, Ilaria; Alexander, Richard; Roberge, Aki

    2009-01-01

    This article summarizes a Splinter Session at the Cool Stars XV conference in St. Andrews with 3 review and 4 contributed talks. The speakers have discussed various approaches to understand the structure and evolution of the gas component in protoplanetary disks. These ranged from observational

  6. The evolution of Saccharomycotina yeasts

    Science.gov (United States)

    Associations between traits are prevalent in nature, occurring across a diverse range of taxa and traits. The evolution of trait correlations can be driven by factors intrinsic or extrinsic to an organism, but few studies, especially in microbes, have simultaneously investigated both across a broad ...

  7. Climatic Change and Human Evolution.

    Science.gov (United States)

    Garratt, John R.

    1995-01-01

    Traces the history of the Earth over four billion years, and shows how climate has had an important role to play in the evolution of humans. Posits that the world's rapidly growing human population and its increasing use of energy is the cause of present-day changes in the concentrations of greenhouse gases in the atmosphere. (Author/JRH)

  8. The Evolution of Electronic Publishing.

    Science.gov (United States)

    Lancaster, F. W.

    1995-01-01

    Discusses the evolution of electronic publishing from the early 1960s when computers were used merely to produce conventional printed products to the present move toward networked scholarly publishing. Highlights include library development, periodicals on the Internet, online journals versus paper journals, problems, and the future of…

  9. Social evolution: reciprocity there is.

    Science.gov (United States)

    Taborsky, Michael

    2013-06-03

    The theory of cooperation predicts that altruism can be established by reciprocity, yet empirical evidence from nature is contentious. Increasingly though, experimental results from social vertebrates challenge the nearly exclusive explanatory power of relatedness for the evolution of cooperation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. A simple model for binary star evolution

    International Nuclear Information System (INIS)

    Whyte, C.A.; Eggleton, P.P.

    1985-01-01

    A simple model for calculating the evolution of binary stars is presented. Detailed stellar evolution calculations of stars undergoing mass and energy transfer at various rates are reported and used to identify the dominant physical processes which determine the type of evolution. These detailed calculations are used to calibrate the simple model and a comparison of calculations using the detailed stellar evolution equations and the simple model is made. Results of the evolution of a few binary systems are reported and compared with previously published calculations using normal stellar evolution programs. (author)

  11. The difficulties of systematic reviews.

    Science.gov (United States)

    Westgate, Martin J; Lindenmayer, David B

    2017-10-01

    The need for robust evidence to support conservation actions has driven the adoption of systematic approaches to research synthesis in ecology. However, applying systematic review to complex or open questions remains challenging, and this task is becoming more difficult as the quantity of scientific literature increases. We drew on the science of linguistics for guidance as to why the process of identifying and sorting information during systematic review remains so labor intensive, and to provide potential solutions. Several linguistic properties of peer-reviewed corpora-including nonrandom selection of review topics, small-world properties of semantic networks, and spatiotemporal variation in word meaning-greatly increase the effort needed to complete the systematic review process. Conversely, the resolution of these semantic complexities is a common motivation for narrative reviews, but this process is rarely enacted with the rigor applied during linguistic analysis. Therefore, linguistics provides a unifying framework for understanding some key challenges of systematic review and highlights 2 useful directions for future research. First, in cases where semantic complexity generates barriers to synthesis, ecologists should consider drawing on existing methods-such as natural language processing or the construction of research thesauri and ontologies-that provide tools for mapping and resolving that complexity. These tools could help individual researchers classify research material in a more robust manner and provide valuable guidance for future researchers on that topic. Second, a linguistic perspective highlights that scientific writing is a rich resource worthy of detailed study, an observation that can sometimes be lost during the search for data during systematic review or meta-analysis. For example, mapping semantic networks can reveal redundancy and complementarity among scientific concepts, leading to new insights and research questions. Consequently

  12. A Systematic Method for Search Term Selection in Systematic Reviews

    Science.gov (United States)

    Thompson, Jenna; Davis, Jacqueline; Mazerolle, Lorraine

    2014-01-01

    The wide variety of readily available electronic media grants anyone the freedom to retrieve published references from almost any area of research around the world. Despite this privilege, keeping up with primary research evidence is almost impossible because of the increase in professional publishing across disciplines. Systematic reviews are a…

  13. Galaxy Workflows for Web-based Bioinformatics Analysis of Aptamer High-throughput Sequencing Data

    Directory of Open Access Journals (Sweden)

    William H Thiel

    2016-01-01

    Full Text Available Development of RNA and DNA aptamers for diagnostic and therapeutic applications is a rapidly growing field. Aptamers are identified through iterative rounds of selection in a process termed SELEX (Systematic Evolution of Ligands by EXponential enrichment. High-throughput sequencing (HTS revolutionized the modern SELEX process by identifying millions of aptamer sequences across multiple rounds of aptamer selection. However, these vast aptamer HTS datasets necessitated bioinformatics techniques. Herein, we describe a semiautomated approach to analyze aptamer HTS datasets using the Galaxy Project, a web-based open source collection of bioinformatics tools that were originally developed to analyze genome, exome, and transcriptome HTS data. Using a series of Workflows created in the Galaxy webserver, we demonstrate efficient processing of aptamer HTS data and compilation of a database of unique aptamer sequences. Additional Workflows were created to characterize the abundance and persistence of aptamer sequences within a selection and to filter sequences based on these parameters. A key advantage of this approach is that the online nature of the Galaxy webserver and its graphical interface allow for the analysis of HTS data without the need to compile code or install multiple programs.

  14. Selection and characterization of single stranded DNA aptamers recognizing fumonisin B1

    International Nuclear Information System (INIS)

    Chen, Xiujuan; Huang, Yukun; Duan, Nuo; Wu, Shijia; Xia, Yu; Ma, Xiaoyuan; Ding, Zhansheng; Wang, Zhouping; Zhu, Changqing; Jiang, Yuan

    2014-01-01

    We present an improved method for the selection of single-stranded DNA aptamers that can recognize fumonisin B 1 (FB 1 ). FB 1 is a carcinogenic mycotoxin mainly found in corn and corn-based food products worldwide, posing a global threat to feed and food safety. Selection was based on the mag-SELEX (magnetic bead systematic evolution of ligands by exponential enrichment) technology modified by adopting free analogs of targets rather than immobilized targets for counter selections. Firstly, aptamer candidates for FB 1 were selected from an 80 nt random DNA library after 13 rounds of selection. Next, binding assays were performed for affinity evaluation, and circular dichroism spectroscopy was used to investigate their conformation. A high-affinity aptamer designated as F10 (with a dissociation constant of 62 ± 5 nM) was identified and tested for its specificity by competitive binding assays. The results demonstrate that this improved mag-SELEX technology facilitates aptamer screening because it avoids the tedious immobilization of counter-selection molecules on magnetic beads. The aptamers obtained by this technique open new possibilities for the detection of FB 1 via aptasensors. (author)

  15. Screening and Initial Binding Assessment of Fumonisin B1 Aptamers

    Directory of Open Access Journals (Sweden)

    Maria C. DeRosa

    2010-11-01

    Full Text Available Fumonisins are mycotoxins produced by Fusarium verticillioides and F. proliferatum, fungi that are ubiquitous in corn (maize. Insect damage and some other environmental conditions result in the accumulation of fumonisins in corn-based products worldwide. Current methods of fumonisin detection rely on the use of immunoaffinity columns and high-performance liquid chromatography (HPLC. The use of aptamers offers a good alternative to the use of antibodies in fumonisin cleanup and detection due to lower costs and improved stability. Aptamers are single-stranded oligonucleotides that are selected using Systematic Evolution of Ligands by EXponential enrichment (SELEX for their ability to bind to targets with high affinity and specificity. Sequences obtained after 18 rounds of SELEX were screened for their ability to bind to fumonisin B1. Six unique sequences were obtained, each showing improved binding to fumonisin B1 compared to controls. Sequence FB1 39 binds to fumonisin with a dissociation constant of 100 ± 30 nM and shows potential for use in fumonisin biosensors and solid phase extraction columns.

  16. Selection and characterization of single stranded DNA aptamers recognizing fumonisin B{sub 1}

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiujuan; Huang, Yukun; Duan, Nuo; Wu, Shijia; Xia, Yu; Ma, Xiaoyuan; Ding, Zhansheng; Wang, Zhouping [State Key Laboratory of Food Science and Technology, Synergetic Innovation Center of Food Safety and Nutrition, School of Food Science and Technology, Jiangnan University, Wuxi, 214122 (China); Zhu, Changqing; Jiang, Yuan [Animal, Plant and Food Inspection Centre, Jiangsu Entry-Exit Inspection and Quarantine Bureau, Nanjing, 210001 (China)

    2014-08-01

    We present an improved method for the selection of single-stranded DNA aptamers that can recognize fumonisin B{sub 1} (FB{sub 1}). FB{sub 1} is a carcinogenic mycotoxin mainly found in corn and corn-based food products worldwide, posing a global threat to feed and food safety. Selection was based on the mag-SELEX (magnetic bead systematic evolution of ligands by exponential enrichment) technology modified by adopting free analogs of targets rather than immobilized targets for counter selections. Firstly, aptamer candidates for FB{sub 1} were selected from an 80 nt random DNA library after 13 rounds of selection. Next, binding assays were performed for affinity evaluation, and circular dichroism spectroscopy was used to investigate their conformation. A high-affinity aptamer designated as F10 (with a dissociation constant of 62 ± 5 nM) was identified and tested for its specificity by competitive binding assays. The results demonstrate that this improved mag-SELEX technology facilitates aptamer screening because it avoids the tedious immobilization of counter-selection molecules on magnetic beads. The aptamers obtained by this technique open new possibilities for the detection of FB{sub 1} via aptasensors. (author)

  17. Ultrasensitive norovirus detection using DNA aptasensor technology.

    Directory of Open Access Journals (Sweden)

    Amanda Giamberardino

    Full Text Available DNA aptamers were developed against murine norovirus (MNV using SELEX (Systematic Evolution of Ligands by EXponential enrichment. Nine rounds of SELEX led to the discovery of AG3, a promising aptamer with very high affinity for MNV as well as for lab-synthesized capsids of a common human norovirus (HuNoV outbreak strain (GII.3. Using fluorescence anisotropy, AG3 was found to bind with MNV with affinity in the low picomolar range. The aptamer could cross-react with HuNoV though it was selected against MNV. As compared to a non-specific DNA control sequence, the norovirus-binding affinity of AG3 was about a million-fold higher. In further tests, the aptamer also showed nearly a million-fold higher affinity for the noroviruses than for the feline calicivirus (FCV, a virus similar in size and structure to noroviruses. AG3 was incorporated into a simple electrochemical sensor using a gold nanoparticle-modified screen-printed carbon electrode (GNPs-SPCE. The aptasensor could detect MNV with a limit of detection of approximately 180 virus particles, for possible on-site applications. The lead aptamer candidate and the aptasensor platform show promise for the rapid detection and identification of noroviruses in environmental and clinical samples.

  18. Development of anti β glucan aptamers for use as radiopharmaceutical in the identification of fungal Infections

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda, Camila Maria de Sousa; Reis, Mariana Flister; Correa, Cristiane Rodrigues; Andrade, Antero S.R., E-mail: cmsl@cdtn.br, E-mail: antero@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEM-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    Invasive fungal infections caused by Candida albicans, are recognized as a major cause of morbidity and mortality in immuno compromised individuals. Patients may not show obvious clinical signs or symptoms, making it difficult to detect its origin or new focus that developed through hematogenous spread. Nuclear medicine could contribute to an early diagnosis of fungal infections, since specific markers are available. The aim of this study was to develop, through SELEX technique (Systematic Evolution of Ligands by Exponential Enrichment), aptamers for beta glucan for subsequent labeling with {sup 99}mTc and evaluation of this radiopharmaceutical in the diagnosis of invasive fungal infections, scintigraphy. To obtain aptamers were performed 15 cycles of SELEX technique, using centrifugation as separation method of oligonuclotideos linked to the beta-glucan is not connected. The DNA bands were observed in all 15 cycles. The oligonucleotides obtained after cycles were cloned using the standard protocol kit-Topo TA vector (Invitrogen), and subjected to sequencing Megabase. Three aptamers for yeast cells were selected for this study. Further, other studies should be performed to assess the specificity and affinity thereof for later use in the diagnosis of fungal infections. (author)

  19. Novel Members of the Cra Regulon Involved in Carbon Metabolism in Escherichia coli▿ †

    Science.gov (United States)

    Shimada, Tomohiro; Yamamoto, Kaneyoshi; Ishihama, Akira

    2011-01-01

    Cra (catabolite repressor activator) is a global regulator of the genes for carbon metabolism in Escherichia coli. To gain insights into the regulatory roles of Cra, attempts were made to identify the whole set of regulation targets using an improved genomic SELEX (systematic evolution of ligands by exponential enrichment) system. Surprisingly, a total of 164 binding sites were identified for Cra, 144 (88%) of which were newly identified. The majority of known targets were included in the SELEX chip pattern. The promoters examined by the lacZ reporter assay in vivo were all regulated by Cra. These two lines of evidence indicate that a total of as many as 178 promoters are under the control of Cra. The majority of Cra targets are the genes coding for the enzymes involved in central carbon metabolism, covering all the genes for the enzymes involved in glycolysis and metabolism downstream of glycolysis, including the tricarboxylic acid (TCA) cycle and aerobic respiration. Taken together, we propose that Cra plays a key role in balancing the levels of the enzymes for carbon metabolism. PMID:21115656

  20. Novel members of the Cra regulon involved in carbon metabolism in Escherichia coli.

    Science.gov (United States)

    Shimada, Tomohiro; Yamamoto, Kaneyoshi; Ishihama, Akira

    2011-02-01

    Cra (catabolite repressor activator) is a global regulator of the genes for carbon metabolism in Escherichia coli. To gain insights into the regulatory roles of Cra, attempts were made to identify the whole set of regulation targets using an improved genomic SELEX (systematic evolution of ligands by exponential enrichment) system. Surprisingly, a total of 164 binding sites were identified for Cra, 144 (88%) of which were newly identified. The majority of known targets were included in the SELEX chip pattern. The promoters examined by the lacZ reporter assay in vivo were all regulated by Cra. These two lines of evidence indicate that a total of as many as 178 promoters are under the control of Cra. The majority of Cra targets are the genes coding for the enzymes involved in central carbon metabolism, covering all the genes for the enzymes involved in glycolysis and metabolism downstream of glycolysis, including the tricarboxylic acid (TCA) cycle and aerobic respiration. Taken together, we propose that Cra plays a key role in balancing the levels of the enzymes for carbon metabolism.

  1. Manufacturing of a novel double-function ssDNA aptamer for sensitive diagnosis and efficient neutralization of SEA.

    Science.gov (United States)

    Sedighian, Hamid; Halabian, Raheleh; Amani, Jafar; Heiat, Mohammad; Taheri, Ramezan Ali; Imani Fooladi, Abbas Ali

    2018-05-01

    Staphylococcal enterotoxin A (SEA) is an enterotoxin produced mainly by Staphylococcus aureus. In recent years, it has become the most prevalent compound for staphylococcal food poisoning (SFP) around the world. In this study, we isolate new dual-function single-stranded DNA (ssDNA) aptamers by using some new methods, such as the Taguchi method, by focusing on the detection and neutralization of SEA enterotoxin in food and clinical samples. For the asymmetric polymerase chain reaction (PCR) optimization of each round of systematic evolution of ligands by exponential enrichment (SELEX), we use Taguchi L9 orthogonal arrays, and the aptamer mobility shift assay (AMSA) is used for initial evaluation of the protein-DNA interactions on the last SELEX round. In our investigation the dissociation constant (K D ) value and the limit of detection (LOD) of the candidate aptamer were found to be 8.5 ± 0.91 of nM and 5 ng/ml using surface plasmon resonance (SPR). In the current study, the Taguchi and mobility shift assay methods were innovatively harnessed to improve the selection process and evaluate the protein-aptamer interactions. To the best of our knowledge, this is the first report on employing these two methods in aptamer technology especially against bacterial toxin. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. Development of anti β glucan aptamers for use as radiopharmaceutical in the identification of fungal Infections

    International Nuclear Information System (INIS)

    Lacerda, Camila Maria de Sousa; Reis, Mariana Flister; Correa, Cristiane Rodrigues; Andrade, Antero S.R.

    2013-01-01

    Invasive fungal infections caused by Candida albicans, are recognized as a major cause of morbidity and mortality in immuno compromised individuals. Patients may not show obvious clinical signs or symptoms, making it difficult to detect its origin or new focus that developed through hematogenous spread. Nuclear medicine could contribute to an early diagnosis of fungal infections, since specific markers are available. The aim of this study was to develop, through SELEX technique (Systematic Evolution of Ligands by Exponential Enrichment), aptamers for beta glucan for subsequent labeling with 99 mTc and evaluation of this radiopharmaceutical in the diagnosis of invasive fungal infections, scintigraphy. To obtain aptamers were performed 15 cycles of SELEX technique, using centrifugation as separation method of oligonuclotideos linked to the beta-glucan is not connected. The DNA bands were observed in all 15 cycles. The oligonucleotides obtained after cycles were cloned using the standard protocol kit-Topo TA vector (Invitrogen), and subjected to sequencing Megabase. Three aptamers for yeast cells were selected for this study. Further, other studies should be performed to assess the specificity and affinity thereof for later use in the diagnosis of fungal infections. (author)

  3. Evolution of the social network of scientific collaborations

    Science.gov (United States)

    Barabási, A. L.; Jeong, H.; Néda, Z.; Ravasz, E.; Schubert, A.; Vicsek, T.

    2002-08-01

    The co-authorship network of scientists represents a prototype of complex evolving networks. In addition, it offers one of the most extensive database to date on social networks. By mapping the electronic database containing all relevant journals in mathematics and neuro-science for an 8-year period (1991-98), we infer the dynamic and the structural mechanisms that govern the evolution and topology of this complex system. Three complementary approaches allow us to obtain a detailed characterization. First, empirical measurements allow us to uncover the topological measures that characterize the network at a given moment, as well as the time evolution of these quantities. The results indicate that the network is scale-free, and that the network evolution is governed by preferential attachment, affecting both internal and external links. However, in contrast with most model predictions the average degree increases in time, and the node separation decreases. Second, we propose a simple model that captures the network's time evolution. In some limits the model can be solved analytically, predicting a two-regime scaling in agreement with the measurements. Third, numerical simulations are used to uncover the behavior of quantities that could not be predicted analytically. The combined numerical and analytical results underline the important role internal links play in determining the observed scaling behavior and network topology. The results and methodologies developed in the context of the co-authorship network could be useful for a systematic study of other complex evolving networks as well, such as the world wide web, Internet, or other social networks.

  4. A Nonstationary Markov Model Detects Directional Evolution in Hymenopteran Morphology.

    Science.gov (United States)

    Klopfstein, Seraina; Vilhelmsen, Lars; Ronquist, Fredrik

    2015-11-01

    Directional evolution has played an important role in shaping the morphological, ecological, and molecular diversity of life. However, standard substitution models assume stationarity of the evolutionary process over the time scale examined, thus impeding the study of directionality. Here we explore a simple, nonstationary model of evolution for discrete data, which assumes that the state frequencies at the root differ from the equilibrium frequencies of the homogeneous evolutionary process along the rest of the tree (i.e., the process is nonstationary, nonreversible, but homogeneous). Within this framework, we develop a Bayesian approach for testing directional versus stationary evolution using a reversible-jump algorithm. Simulations show that when only data from extant taxa are available, the success in inferring directionality is strongly dependent on the evolutionary rate, the shape of the tree, the relative branch lengths, and the number of taxa. Given suitable evolutionary rates (0.1-0.5 expected substitutions between root and tips), accounting for directionality improves tree inference and often allows correct rooting of the tree without the use of an outgroup. As an empirical test, we apply our method to study directional evolution in hymenopteran morphology. We focus on three character systems: wing veins, muscles, and sclerites. We find strong support for a trend toward loss of wing veins and muscles, while stationarity cannot be ruled out for sclerites. Adding fossil and time information in a total-evidence dating approach, we show that accounting for directionality results in more precise estimates not only of the ancestral state at the root of the tree, but also of the divergence times. Our model relaxes the assumption of stationarity and reversibility by adding a minimum of additional parameters, and is thus well suited to studying the nature of the evolutionary process in data sets of limited size, such as morphology and ecology. © The Author

  5. Decoding flow unit evolution upon annealing from fracture morphology in metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Gao, M., E-mail: gaomeng10@hotmail.com; Cao, X.F.; Ding, D.W.; Wang, B.B.; Wang, W.H., E-mail: whw@iphy.ac.cn

    2017-02-16

    The intrinsic correlation between the fracture morphology evolution and the structural heterogeneity of flow units in a typical Zr{sub 52.5}Ti{sub 5}Cu{sub 17.9}Ni{sub 14.6}Al{sub 10} (vit105) metallic glass (MG) upon annealing was investigated. By systematically tuning the annealing time at temperature below the glass transition temperature, a series of dimple-like fracture morphology were obtained, which is the unique fingerprint-like pattern for every annealing state. Based on the structural relaxation model of flow units, the evolution of the typical dimple sizes, the largest and smallest dimple size, with annealing were well fitted. Then the evolution of flow unit density was estimated from the fracture morphology evolution, which displays the same evolution trend with that measured from thermal relaxation. A stochastic dynamic model considering the interaction of activated flow units was proposed to analyze the effect of the initial flow unit density and the flow unit interaction intensity on the dynamic evolution of dimple distribution. Our work may provide a novel scheme to investigate the structural fingerprint information on flow units from fracture morphology, and enlighten the microscopic structural origin of the ductile-to-brittle transition during structural relaxation in MGs.

  6. Evolution of energy structures; Evolution des structures energetiques

    Energy Technology Data Exchange (ETDEWEB)

    Nifenecker, H. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France)

    2005-07-01

    Because of the big inertia and long time constants of energy systems, their long-time behaviour is mainly determined by their present day state and by the trends of their recent evolution. For this reason, it is of prime importance to foresee the evolution of the different energy production sources which may play an important role in the future. A status of the world energy consumption and production is made first using the energy statistics of the IEA. Then, using the trends observed since 1973, the consequences of a simple extrapolation of these trends is examined. Finally, the scenarios of forecasting of energy structures, like those supplied by the International institute for applied systems analysis (IIASA) are discussed. (J.S.)

  7. Cognitive Evolution and Religion: Cognition and Religious Evolution

    Directory of Open Access Journals (Sweden)

    Harvey Whitehouse

    2016-03-01

    Full Text Available This paper presents contemporary cognitive approaches to the evolution of religious beliefs. Arguments are put forward that different types of beliefs, or ‘modes of religiosity’, occur as a result of a number of evolutionary factors (biological, cultural, socio-political etc. At the same time, religions across the world retain a significant level of common and shared elements, also explained in evolutionary terms.

  8. Relation between Hydrogen Evolution and Hydrodesulfurization Catalysis

    DEFF Research Database (Denmark)

    Šaric, Manuel; Moses, Poul Georg; Rossmeisl, Jan

    2016-01-01

    A relation between hydrogen evolution and hydrodesulfurization catalysis was found by density functional theory calculations. The hydrogen evolution reaction and the hydrogenation reaction in hydrodesulfurization share hydrogen as a surface intermediate and, thus, have a common elementary step...

  9. A comparison of biological and cultural evolution

    Indian Academy of Sciences (India)

    the intellectual and moral characters of man have emerged as results of biological ..... tural selection is at least partly based on conscious action. In cultural evolution .... Transfer of information in biological and cultural evolution. In biological.

  10. Bicep2. III. INSTRUMENTAL SYSTEMATICS

    International Nuclear Information System (INIS)

    Ade, P. A. R.; Aikin, R. W.; Bock, J. J.; Brevik, J. A.; Filippini, J. P.; Golwala, S. R.; Hildebrandt, S. R.; Barkats, D.; Benton, S. J.; Bischoff, C. A.; Buder, I.; Karkare, K. S.; Bullock, E.; Dowell, C. D.; Duband, L.; Fliescher, S.; Halpern, M.; Hasselfield, M.; Hilton, G. C.; Irwin, K. D.

    2015-01-01

    In a companion paper, we have reported a >5σ detection of degree scale B-mode polarization at 150 GHz by the Bicep2 experiment. Here we provide a detailed study of potential instrumental systematic contamination to that measurement. We focus extensively on spurious polarization that can potentially arise from beam imperfections. We present a heuristic classification of beam imperfections according to their symmetries and uniformities, and discuss how resulting contamination adds or cancels in maps that combine observations made at multiple orientations of the telescope about its boresight axis. We introduce a technique, which we call “deprojection,” for filtering the leading order beam-induced contamination from time-ordered data, and show that it reduces power in Bicep2's actual and null-test BB spectra consistent with predictions using high signal-to-noise beam shape measurements. We detail the simulation pipeline that we use to directly simulate instrumental systematics and the calibration data used as input to that pipeline. Finally, we present the constraints on BB contamination from individual sources of potential systematics. We find that systematics contribute BB power that is a factor of ∼10× below Bicep2's three-year statistical uncertainty, and negligible compared to the observed BB signal. The contribution to the best-fit tensor/scalar ratio is at a level equivalent to r = (3–6) × 10 −3

  11. Bicep2. III. INSTRUMENTAL SYSTEMATICS

    Energy Technology Data Exchange (ETDEWEB)

    Ade, P. A. R. [School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA (United Kingdom); Aikin, R. W.; Bock, J. J.; Brevik, J. A.; Filippini, J. P.; Golwala, S. R.; Hildebrandt, S. R. [Department of Physics, California Institute of Technology, Pasadena, CA 91125 (United States); Barkats, D. [Joint ALMA Observatory, ESO, Santiago (Chile); Benton, S. J. [Department of Physics, University of Toronto, Toronto, ON (Canada); Bischoff, C. A.; Buder, I.; Karkare, K. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS 42, Cambridge, MA 02138 (United States); Bullock, E. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Dowell, C. D. [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Duband, L. [SBT, Commissariat à l’Energie Atomique, Grenoble (France); Fliescher, S. [Department of Physics, University of Minnesota, Minneapolis, MN 55455 (United States); Halpern, M.; Hasselfield, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC (Canada); Hilton, G. C.; Irwin, K. D., E-mail: csheehy@uchicago.edu [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Collaboration: Bicep2 Collaboration; and others

    2015-12-01

    In a companion paper, we have reported a >5σ detection of degree scale B-mode polarization at 150 GHz by the Bicep2 experiment. Here we provide a detailed study of potential instrumental systematic contamination to that measurement. We focus extensively on spurious polarization that can potentially arise from beam imperfections. We present a heuristic classification of beam imperfections according to their symmetries and uniformities, and discuss how resulting contamination adds or cancels in maps that combine observations made at multiple orientations of the telescope about its boresight axis. We introduce a technique, which we call “deprojection,” for filtering the leading order beam-induced contamination from time-ordered data, and show that it reduces power in Bicep2's actual and null-test BB spectra consistent with predictions using high signal-to-noise beam shape measurements. We detail the simulation pipeline that we use to directly simulate instrumental systematics and the calibration data used as input to that pipeline. Finally, we present the constraints on BB contamination from individual sources of potential systematics. We find that systematics contribute BB power that is a factor of ∼10× below Bicep2's three-year statistical uncertainty, and negligible compared to the observed BB signal. The contribution to the best-fit tensor/scalar ratio is at a level equivalent to r = (3–6) × 10{sup −3}.

  12. Methodology of a systematic review.

    Science.gov (United States)

    Linares-Espinós, E; Hernández, V; Domínguez-Escrig, J L; Fernández-Pello, S; Hevia, V; Mayor, J; Padilla-Fernández, B; Ribal, M J

    2018-05-03

    The objective of evidence-based medicine is to employ the best scientific information available to apply to clinical practice. Understanding and interpreting the scientific evidence involves understanding the available levels of evidence, where systematic reviews and meta-analyses of clinical trials are at the top of the levels-of-evidence pyramid. The review process should be well developed and planned to reduce biases and eliminate irrelevant and low-quality studies. The steps for implementing a systematic review include (i) correctly formulating the clinical question to answer (PICO), (ii) developing a protocol (inclusion and exclusion criteria), (iii) performing a detailed and broad literature search and (iv) screening the abstracts of the studies identified in the search and subsequently of the selected complete texts (PRISMA). Once the studies have been selected, we need to (v) extract the necessary data into a form designed in the protocol to summarise the included studies, (vi) assess the biases of each study, identifying the quality of the available evidence, and (vii) develop tables and text that synthesise the evidence. A systematic review involves a critical and reproducible summary of the results of the available publications on a particular topic or clinical question. To improve scientific writing, the methodology is shown in a structured manner to implement a systematic review. Copyright © 2018 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

  13. The Evolution and Extinction of the Dinosaurs

    Science.gov (United States)

    Fastovsky, David E.; Weishampel, David B.

    2005-02-01

    Written for non-specialists, this detailed survey of dinosaur origins, diversity, and extinction is designed as a series of successive essays covering important and timely topics in dinosaur paleobiology, such as "warm-bloodedness," birds as living dinosaurs, the new, non-flying feathered dinosaurs, dinosaur functional morphology, and cladistic methods in systematics. Its explicitly phylogenetic approach to the group is that taken by dinosaur specialists. The book is not an edited compilation of the works of many individuals, but a unique, cohesive perspective on Dinosauria. Lavishly illustrated with hundreds of new, specially commissioned illustrations by John Sibbick, world-famous illustrator of dinosaurs, the volume includes multi-page drawings as well as sketches and diagrams. First edition Hb (1996): 0-521-44496-9 David E. Fastovsky is Professor of Geosciences at the University of Rhode Island. Fastovsky, the author of numerous scientific publications dealing with Mesozoic vertebrate faunas and their ancient environments, is also scientific co-Editor of Geology. He has undertaken extensive fieldwork studying dinosaurs and their environments in Montana, North Dakota, Arizona, Mexico, and Mongolia. David B. Weishampel is a professor at the Center for Functional Anatomy and Evolution at Johns Hopkins University, School of Medicine. Weishampel is best known for discovering, researching, and naming several rare European dinosaur species. During the 1980s Weishampel gained fame for his work with American paleontologist Jack Horner and later named the famous plant-eating, egg-laying Orodromeus, Horner. Now, a decade after his pioneering studies with Horner, Weishampel is most widely known for his current work on the Romanian dinosaur fauna. He is the author and co-author of many titles, including The Dinosaur Papers, 1676-1906 (Norton, 2003); The Dinosauria, (University of California, 1990); and Dinosaurs of the East Coast, (Johns Hopkins University Press, 1996).

  14. Constraining Cosmic Evolution of Type Ia Supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Foley, Ryan J.; Filippenko, Alexei V.; Aguilera, C.; Becker, A.C.; Blondin, S.; Challis, P.; Clocchiatti, A.; Covarrubias, R.; Davis, T.M.; Garnavich, P.M.; Jha, S.; Kirshner, R.P.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miceli, A.; Miknaitis, G.; Pignata, G.; Rest, A.; Riess, A.G.; /UC, Berkeley, Astron. Dept. /Cerro-Tololo InterAmerican Obs. /Washington U., Seattle, Astron. Dept. /Harvard-Smithsonian Ctr. Astrophys. /Chile U., Catolica /Bohr Inst. /Notre Dame U. /KIPAC, Menlo Park /Texas A-M /European Southern Observ. /NOAO, Tucson /Fermilab /Chile U., Santiago /Harvard U., Phys. Dept. /Baltimore, Space Telescope Sci. /Johns Hopkins U. /Res. Sch. Astron. Astrophys., Weston Creek /Stockholm U. /Hawaii U. /Illinois U., Urbana, Astron. Dept.

    2008-02-13

    We present the first large-scale effort of creating composite spectra of high-redshift type Ia supernovae (SNe Ia) and comparing them to low-redshift counterparts. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with excellent light-curve information. In addition, we have obtained 397 spectra of low-redshift SNe through a multiple-decade effort at Lick and Keck Observatories, and we have used 45 ultraviolet spectra obtained by HST/IUE. The low-redshift spectra act as a control sample when comparing to the ESSENCE spectra. In all instances, the ESSENCE and Lick composite spectra appear very similar. The addition of galaxy light to the Lick composite spectra allows a nearly perfect match of the overall spectral-energy distribution with the ESSENCE composite spectra, indicating that the high-redshift SNe are more contaminated with host-galaxy light than their low-redshift counterparts. This is caused by observing objects at all redshifts with similar slit widths, which corresponds to different projected distances. After correcting for the galaxy-light contamination, subtle differences in the spectra remain. We have estimated the systematic errors when using current spectral templates for K-corrections to be {approx}0.02 mag. The variance in the composite spectra give an estimate of the intrinsic variance in low-redshift maximum-light SN spectra of {approx}3% in the optical and growing toward the ultraviolet. The difference between the maximum-light low and high-redshift spectra constrain SN evolution between our samples to be < 10% in the rest-frame optical.

  15. GALAXY CLUSTERS AT HIGH REDSHIFT AND EVOLUTION OF BRIGHTEST CLUSTER GALAXIES

    International Nuclear Information System (INIS)

    Wen, Z. L.; Han, J. L.

    2011-01-01

    Identification of high-redshift clusters is important for studies of cosmology and cluster evolution. Using photometric redshifts of galaxies, we identify 631 clusters from the Canada-France-Hawaii Telescope (CFHT) wide field, 202 clusters from the CFHT deep field, 187 clusters from the Cosmic Evolution Survey (COSMOS) field, and 737 clusters from the Spitzer Wide-area InfraRed Extragalactic Survey (SWIRE) field. The redshifts of these clusters are in the range 0.1 ∼ + - m 3.6 μ m colors of the BCGs are consistent with a stellar population synthesis model in which the BCGs are formed at redshift z f ≥ 2 and evolved passively. The g' - z' and B - m 3.6μm colors of the BCGs at redshifts z > 0.8 are systematically bluer than the passive evolution model for galaxies formed at z f ∼ 2, indicating star formation in high-redshift BCGs.

  16. Nanocluster irradiation evolution in Fe-9%Cr ODS and ferritic-martensitic alloys

    Science.gov (United States)

    Swenson, M. J.; Wharry, J. P.

    2017-12-01

    The objective of this study is to evaluate the influence of dose rate and cascade morphology on nanocluster evolution in a model Fe-9%Cr oxide dispersion strengthened steel and the commercial ferritic/martensitic (F/M) alloys HCM12A and HT9. We present a large, systematic data set spanning the three alloys, three irradiating particle types, four orders of magnitude in dose rate, and doses ranging 1-100 displacements per atom over 400-500 °C. Nanoclusters are characterized using atom probe tomography. ODS oxide nanoclusters experience partial dissolution after irradiation due to inverse Ostwald ripening, while F/M nanoclusters undergo Ostwald ripening. Damage cascade morphology is indicative of nanocluster number density evolution. Finally, the effects of dose rate on nanocluster morphology provide evidence for a temperature dilation theory, which purports that a negative temperature shift is necessary for higher dose rate irradiations to emulate nanocluster evolution in lower dose rate irradiations.

  17. Luminosity profiles and the evolution of shock waves in general relativistic radiating spheres

    International Nuclear Information System (INIS)

    Herrera, L.; Nunez, L.A.

    1989-10-01

    A method recently proposed by the authors to study the evolution of discontinuities in radiating spherically symmetric distributions of matter is systematically applied to model the evolution of a composite radiant sphere. The matter configuration, free of singularities, is divided in two regions by a shock wave front, and at each side of this interface a different equation of state is considered. Solutions are matched across the shock via the Rankine-Hugoniot conditions while the outer region metric joins the Vaidya solution at the boundary surface. The influence on the evolution of these composite spheres of different shapes of neutrino outburst profiles, and particular neutrino-transfer processes from the inner core to the outer mantel is explored. Prospective applications to supernova scenarios are discussed. (author). 18 refs, 4 figs, 1 tab

  18. Spectral evolution of galaxies: current views

    International Nuclear Information System (INIS)

    Bruzual, A.G.

    1985-01-01

    A summary of current views on the interpretation of the various evolutionary tests aimed at detecting spectral evolution in galaxies is presented. It is concluded that the evolution taking place in known galaxy samples is a slow process (perhaps consistent with no evolution at all), and that the early phases of rapid spectral evolution in early-type galaxies have not yet been detected. (author)

  19. Assessing Technical Competence in Surgical Trainees: A Systematic Review.

    Science.gov (United States)

    Szasz, Peter; Louridas, Marisa; Harris, Kenneth A; Aggarwal, Rajesh; Grantcharov, Teodor P

    2015-06-01

    To systematically examine the literature describing the methods by which technical competence is assessed in surgical trainees. The last decade has witnessed an evolution away from time-based surgical education. In response, governing bodies worldwide have implemented competency-based education paradigms. The definition of competence, however, remains elusive, and the impact of these education initiatives in terms of assessment methods remains unclear. A systematic review examining the methods by which technical competence is assessed was conducted by searching MEDLINE, EMBASE, PsychINFO, and the Cochrane database of systematic reviews. Abstracts of retrieved studies were reviewed and those meeting inclusion criteria were selected for full review. Data were retrieved in a systematic manner, the validity and reliability of the assessment methods was evaluated, and quality was assessed using the Grading of Recommendations Assessment, Development and Evaluation classification. Of the 6814 studies identified, 85 studies involving 2369 surgical residents were included in this review. The methods used to assess technical competence were categorized into 5 groups; Likert scales (37), benchmarks (31), binary outcomes (11), novel tools (4), and surrogate outcomes (2). Their validity and reliability were mostly previously established. The overall Grading of Recommendations Assessment, Development and Evaluation for randomized controlled trials was high and low for the observational studies. The definition of technical competence continues to be debated within the medical literature. The methods used to evaluate technical competence predominantly include instruments that were originally created to assess technical skill. Very few studies identify standard setting approaches that differentiate competent versus noncompetent performers; subsequently, this has been identified as an area with great research potential.

  20. Quality of systematic reviews in pediatric oncology--a systematic review

    DEFF Research Database (Denmark)

    Lundh, Andreas; Knijnenburg, Sebastiaan L; Jørgensen, Anders W

    2009-01-01

    BACKGROUND: To ensure evidence-based decision making in pediatric oncology systematic reviews are necessary. The objective of our study was to evaluate the methodological quality of all currently existing systematic reviews in pediatric oncology. METHODS: We identified eligible systematic reviews...... through a systematic search of the literature. Data on clinical and methodological characteristics of the included systematic reviews were extracted. The methodological quality of the included systematic reviews was assessed using the overview quality assessment questionnaire, a validated 10-item quality...... assessment tool. We compared the methodological quality of systematic reviews published in regular journals with that of Cochrane systematic reviews. RESULTS: We included 117 systematic reviews, 99 systematic reviews published in regular journals and 18 Cochrane systematic reviews. The average methodological...