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Sample records for additional sex combs

  1. Genetic Analysis of the Additional Sex Combs Locus of Drosophila Melanogaster

    OpenAIRE

    Sinclair, DAR.; Campbell, R. B.; Nicholls, F.; Slade, E.; Brock, H. W.

    1992-01-01

    Additional sex combs (Asx) is a member of the Polycomb group of genes, which are thought to be required for maintenance of chromatin structure. To better understand the function of Asx, we have isolated nine new alleles, each of which acts like a gain of function mutation. Asx is required for normal determination of segment identity. Asx(P1) shows an unusual phenotype in that anterior and posterior homeotic transformations are seen in the same individuals, suggesting that Asx(P1) might upset ...

  2. Additional sex combs-like 1 belongs to the enhancer of trithorax and Polycomb Group and genetically interacts with Cbx2 in mice

    Science.gov (United States)

    Fisher, C.L.; Lee, I.; Bloyer, S.; Bozza, S.; Chevalier, J.; Dahl, A; Bodner, C.; Helgason, C. D.; Hess, J.L.; Humphries, R.K.; Brock, H.W.

    2009-01-01

    The Additional sex combs (Asx) gene of Drosophila behaves genetically as an enhancer of trithorax and Polycomb (ETP) in displaying bidirectional homeotic phenotypes, suggesting that is required for maintenance of both activation and silencing of Hox genes. There are 3 murine homologs of Asx called Additional sex combs-like1, 2, and-3. Asxl1 is required for normal adult hematopoiesis; however its embryonic function is unknown. We used a targeted mouse mutant line Asxl1tm1Bc to determine if Asxl1 is required to silence and activate Hox genes in mice during axial patterning. The mutant embryos exhibit simultaneous anterior and posterior transformations of the axial skeleton, consistent with a role for Asxl1 in activation and silencing of Hox genes. Transformations of the axial skeleton are enhanced in compound mutant embryos for the Polycomb group gene M33/Cbx2. Hox a4, a7, and c8 are derepressed in Asxl1tm1Bc mutants in the antero-posterior axis, but Hox c8 expression is reduced in the brain of mutants, consistent with Asxl1 being required both for activation and repression of Hox genes. We discuss the genetic and molecular definition of ETPs, and suggest that the function of Asxl1 depends on its cellular context. PMID:19833123

  3. Condition dependence and the nature of genetic variation for male sex comb bristle number in Drosophila melanogaster.

    Science.gov (United States)

    Ahuja, Abha; De Vito, Scott; Singh, Rama S

    2011-04-01

    Genetic architecture of variation underlying male sex comb bristle number, a rapidly evolving secondary sexual character of Drosophila, was examined. First, in order to test for condition dependence, diet was manipulated in a set of ten Drosophila melanogaster full-sib families. We confirmed heightened condition dependent expression of sex comb bristle number and its female homologue (distal transverse row bristles) as compared to non-sex sternopleural bristles. Significant genotype by environment effects were detected for the sex traits indicating a genetic basis for condition dependence. Next we measured sex comb bristle number and sternopleural bristle number, as well as residual mass, a commonly used condition index, in a set of thirty half-sib families. Sire effect was not significant for sex comb and sternopleural bristle number, and we detected a strong dominance and/or maternal effect or X chromosome effect for both traits. A strong sire effect was detected for condition and its heritability was the highest as compared to sex comb and sternopleural bristles. We discuss our results in light of the rapid response to divergent artificial selection for sex comb bristle number reported previously. The nature of genetic variation for male sex traits continues to be an important unresolved issue in evolutionary biology.

  4. Participation of Polycomb group gene extra sex combs in hedgehog signaling pathway

    International Nuclear Information System (INIS)

    Shindo, Norihisa; Sakai, Atsushi; Yamada, Kouji; Higashinakagawa, Toru

    2004-01-01

    Polycomb group (PcG) genes are required for stable inheritance of epigenetic states across cell divisions, a phenomenon termed cellular memory. PcG proteins form multimeric nuclear complex which modifies the chromatin structure of target site. Drosophila PcG gene extra sex combs (esc) and its vertebrate orthologs constitute a member of ESC-E(Z) complex, which possesses histone methyltransferase activity. Here we report isolation and characterization of medaka esc homolog, termed oleed. Hypomorphic knock-down of oleed using morpholino antisense oligonucleotides resulted in the fusion of eyes, termed cyclopia. Prechordal plate formation was not substantially impaired, but expression of hedgehog target genes was dependent on oleed, suggesting some link with hedgehog signaling. In support of this implication, histone methylation, which requires the activity of esc gene product, is increased in hedgehog stimulated mouse NIH-3T3 cells. Our data argue for the novel role of esc in hedgehog signaling and provide fundamental insight into the epigenetic mechanisms in general

  5. Small Ubiquitin-like Modifier (SUMO) Conjugation Impedes Transcriptional Silencing by the Polycomb Group Repressor Sex Comb on Midleg*

    OpenAIRE

    Smith, Matthew; Mallin, Daniel R.; Simon, Jeffrey A.; Courey, Albert J.

    2011-01-01

    The Drosophila protein Sex Comb on Midleg (Scm) is a member of the Polycomb group (PcG), a set of transcriptional repressors that maintain silencing of homeotic genes during development. Recent findings have identified PcG proteins both as targets for modification by the small ubiquitin-like modifier (SUMO) protein and as catalytic components of the SUMO conjugation pathway. We have found that the SUMO-conjugating enzyme Ubc9 binds to Scm and that this interaction, which requires the Scm C-te...

  6. Sex comb on midleg (Scm) is a functional link between PcG-repressive complexes in Drosophila.

    Science.gov (United States)

    Kang, Hyuckjoon; McElroy, Kyle A; Jung, Youngsook Lucy; Alekseyenko, Artyom A; Zee, Barry M; Park, Peter J; Kuroda, Mitzi I

    2015-06-01

    The Polycomb group (PcG) proteins are key regulators of development in Drosophila and are strongly implicated in human health and disease. How PcG complexes form repressive chromatin domains remains unclear. Using cross-linked affinity purifications of BioTAP-Polycomb (Pc) or BioTAP-Enhancer of zeste [E(z)], we captured all PcG-repressive complex 1 (PRC1) or PRC2 core components and Sex comb on midleg (Scm) as the only protein strongly enriched with both complexes. Although previously not linked to PRC2, we confirmed direct binding of Scm and PRC2 using recombinant protein expression and colocalization of Scm with PRC1, PRC2, and H3K27me3 in embryos and cultured cells using ChIP-seq (chromatin immunoprecipitation [ChIP] combined with deep sequencing). Furthermore, we found that RNAi knockdown of Scm and overexpression of the dominant-negative Scm-SAM (sterile α motif) domain both affected the binding pattern of E(z) on polytene chromosomes. Aberrant localization of the Scm-SAM domain in long contiguous regions on polytene chromosomes revealed its independent ability to spread on chromatin, consistent with its previously described ability to oligomerize in vitro. Pull-downs of BioTAP-Scm captured PRC1 and PRC2 and additional repressive complexes, including PhoRC, LINT, and CtBP. We propose that Scm is a key mediator connecting PRC1, PRC2, and transcriptional silencing. Combined with previous structural and genetic analyses, our results strongly suggest that Scm coordinates PcG complexes and polymerizes to produce broad domains of PcG silencing. © 2015 Kang et al.; Published by Cold Spring Harbor Laboratory Press.

  7. Compact electrostatic comb actuator

    Science.gov (United States)

    Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

    2000-01-01

    A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

  8. Small ubiquitin-like modifier (SUMO) conjugation impedes transcriptional silencing by the polycomb group repressor Sex Comb on Midleg.

    Science.gov (United States)

    Smith, Matthew; Mallin, Daniel R; Simon, Jeffrey A; Courey, Albert J

    2011-04-01

    The Drosophila protein Sex Comb on Midleg (Scm) is a member of the Polycomb group (PcG), a set of transcriptional repressors that maintain silencing of homeotic genes during development. Recent findings have identified PcG proteins both as targets for modification by the small ubiquitin-like modifier (SUMO) protein and as catalytic components of the SUMO conjugation pathway. We have found that the SUMO-conjugating enzyme Ubc9 binds to Scm and that this interaction, which requires the Scm C-terminal sterile α motif (SAM) domain, is crucial for the efficient sumoylation of Scm. Scm is associated with the major Polycomb response element (PRE) of the homeotic gene Ultrabithorax (Ubx), and efficient PRE recruitment requires an intact Scm SAM domain. Global reduction of sumoylation augments binding of Scm to the PRE. This is likely to be a direct effect of Scm sumoylation because mutations in the SUMO acceptor sites in Scm enhance its recruitment to the PRE, whereas translational fusion of SUMO to the Scm N terminus interferes with this recruitment. In the metathorax, Ubx expression promotes haltere formation and suppresses wing development. When SUMO levels are reduced, we observe decreased expression of Ubx and partial haltere-to-wing transformation phenotypes. These observations suggest that SUMO negatively regulates Scm function by impeding its recruitment to the Ubx major PRE.

  9. Small Ubiquitin-like Modifier (SUMO) Conjugation Impedes Transcriptional Silencing by the Polycomb Group Repressor Sex Comb on Midleg*

    Science.gov (United States)

    Smith, Matthew; Mallin, Daniel R.; Simon, Jeffrey A.; Courey, Albert J.

    2011-01-01

    The Drosophila protein Sex Comb on Midleg (Scm) is a member of the Polycomb group (PcG), a set of transcriptional repressors that maintain silencing of homeotic genes during development. Recent findings have identified PcG proteins both as targets for modification by the small ubiquitin-like modifier (SUMO) protein and as catalytic components of the SUMO conjugation pathway. We have found that the SUMO-conjugating enzyme Ubc9 binds to Scm and that this interaction, which requires the Scm C-terminal sterile α motif (SAM) domain, is crucial for the efficient sumoylation of Scm. Scm is associated with the major Polycomb response element (PRE) of the homeotic gene Ultrabithorax (Ubx), and efficient PRE recruitment requires an intact Scm SAM domain. Global reduction of sumoylation augments binding of Scm to the PRE. This is likely to be a direct effect of Scm sumoylation because mutations in the SUMO acceptor sites in Scm enhance its recruitment to the PRE, whereas translational fusion of SUMO to the Scm N terminus interferes with this recruitment. In the metathorax, Ubx expression promotes haltere formation and suppresses wing development. When SUMO levels are reduced, we observe decreased expression of Ubx and partial haltere-to-wing transformation phenotypes. These observations suggest that SUMO negatively regulates Scm function by impeding its recruitment to the Ubx major PRE. PMID:21278366

  10. Dual THz comb spectroscopy

    Science.gov (United States)

    Yasui, Takeshi

    2017-08-01

    Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10-7 in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.

  11. Comparative Analysis of Chromatin Binding by Sex Comb on Midleg (SCM) and Other Polycomb Group Repressors at a Drosophila Hox Gene▿

    OpenAIRE

    Wang, Liangjun; Jahren, Neal; Miller, Ellen L.; Ketel, Carrie S.; Mallin, Daniel R.; Simon, Jeffrey A.

    2010-01-01

    Sex Comb on Midleg (SCM) is a transcriptional repressor in the Polycomb group (PcG), but its molecular role in PcG silencing is not known. Although SCM can interact with Polycomb repressive complex 1 (PRC1) in vitro, biochemical studies have indicated that SCM is not a core constituent of PRC1 or PRC2. Nevertheless, SCM is just as critical for Drosophila Hox gene silencing as canonical subunits of these well-characterized PcG complexes. To address functional relationships between SCM and othe...

  12. RNAi analysis of Deformed, proboscipedia and Sex combs reduced in the milkweed bug Oncopeltus fasciatus: novel roles for Hox genes in the hemipteran head.

    Science.gov (United States)

    Hughes, C L; Kaufman, T C

    2000-09-01

    Insects have evolved a large variety of specialized feeding strategies, with a corresponding variability in mouthpart morphology. We have, however, little understanding of the developmental mechanisms that underlie this diversity. Until recently it was difficult to perform any analysis of gene function outside of the genetic model insects Drosophila melanogaster and Tribolium castaneum. In this paper, we report the use of dsRNA-mediated interference (RNAi) to dissect gene function in the development of the milkweed bug Oncopeltus fasciatus, which has specialized suctorial mouthparts. The Hox genes Deformed (Dfd), proboscipedia (pb) and Sex combs reduced (Scr) have previously been shown to be expressed in the gnathal appendages of this species. Strikingly, the milkweed bug was found to have an unusual expression pattern of pb. Here, by analyzing single and combination RNAi depletions, we find that Dfd, pb and Scr are used in the milkweed bug to specify the identity of the mouthparts. The exact roles of the genes, however, are different from what is known in the two genetic model insects. The maxillary appendages in the bug are determined by the activities of the genes Dfd and Scr, rather than Dfd and pb as in the fly and beetle. The mandibular appendages are specified by Dfd, but their unique morphology in Oncopeltus suggests that Dfd's target genes are different. As in flies and beetles, the labium is specified by the combined activities of pb and Scr, but again, the function of pb appears to be different. Additionally, the regulatory control of pb by the other two genes seems to be different in the bug than in either of the other species. These novelties in Hox function, expression pattern and regulatory relationships may have been important for the evolution of the unique Hemipteran head.

  13. A genetic screen in Drosophila implicates Sex comb on midleg (Scm) in tissue overgrowth and mechanisms of Scm degradation by Wds.

    Science.gov (United States)

    Guo, Jiwei; Jin, Dan

    2015-05-01

    The sex comb on midleg (scm) gene encodes a transcriptional repressor and belongs to the Polycomb group (PcG) of genes, which regulates growth in Drosophila. Scm interacts with Polyhomeotic (a PcG protein) in vitro by recognizing its SPM domain. The homologous human protein, Sex comb on midleg-like 2 (Scml2), has been implicated in malignant brain tumors. Will die slowly (Wds) is another factor that regulates Drosophila development, and its homologous human protein, WD repeat domain 5(Wdr5), is part of the mixed lineage leukemia 1(MLL1) complex that promotes histone H3Lys4 methylation. Like Scml2, Wdr5 has been implicated in certain cancers; this protein plays an important role in leukemogenesis. In this study, we find that loss-of-function mutations in Scm result in non-autonomous tissue overgrowth in Drosophila, and determine that Scm is essential for ommatidium development and important for cell survival in Drosophila. Furthermore, our research suggests a relationship between Wds and Scm; Wds promotes Scm degradation through ubiquitination in vitro in Drosophila. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  14. Comparative analysis of chromatin binding by Sex Comb on Midleg (SCM) and other polycomb group repressors at a Drosophila Hox gene.

    Science.gov (United States)

    Wang, Liangjun; Jahren, Neal; Miller, Ellen L; Ketel, Carrie S; Mallin, Daniel R; Simon, Jeffrey A

    2010-06-01

    Sex Comb on Midleg (SCM) is a transcriptional repressor in the Polycomb group (PcG), but its molecular role in PcG silencing is not known. Although SCM can interact with Polycomb repressive complex 1 (PRC1) in vitro, biochemical studies have indicated that SCM is not a core constituent of PRC1 or PRC2. Nevertheless, SCM is just as critical for Drosophila Hox gene silencing as canonical subunits of these well-characterized PcG complexes. To address functional relationships between SCM and other PcG components, we have performed chromatin immunoprecipitation studies using cultured Drosophila Schneider line 2 (S2) cells and larval imaginal discs. We find that SCM associates with a Polycomb response element (PRE) upstream of the Ubx gene which also binds PRC1, PRC2, and the DNA-binding PcG protein Pleiohomeotic (PHO). However, SCM is retained at this Ubx PRE despite genetic disruption or knockdown of PHO, PRC1, or PRC2, suggesting that SCM chromatin targeting does not require prior association of these other PcG components. Chromatin immunoprecipitations (IPs) to test the consequences of SCM genetic disruption or knockdown revealed that PHO association is unaffected, but reduced levels of PRE-bound PRC2 and PRC1 were observed. We discuss these results in light of current models for recruitment of PcG complexes to chromatin targets.

  15. Comparative Analysis of Chromatin Binding by Sex Comb on Midleg (SCM) and Other Polycomb Group Repressors at a Drosophila Hox Gene▿

    Science.gov (United States)

    Wang, Liangjun; Jahren, Neal; Miller, Ellen L.; Ketel, Carrie S.; Mallin, Daniel R.; Simon, Jeffrey A.

    2010-01-01

    Sex Comb on Midleg (SCM) is a transcriptional repressor in the Polycomb group (PcG), but its molecular role in PcG silencing is not known. Although SCM can interact with Polycomb repressive complex 1 (PRC1) in vitro, biochemical studies have indicated that SCM is not a core constituent of PRC1 or PRC2. Nevertheless, SCM is just as critical for Drosophila Hox gene silencing as canonical subunits of these well-characterized PcG complexes. To address functional relationships between SCM and other PcG components, we have performed chromatin immunoprecipitation studies using cultured Drosophila Schneider line 2 (S2) cells and larval imaginal discs. We find that SCM associates with a Polycomb response element (PRE) upstream of the Ubx gene which also binds PRC1, PRC2, and the DNA-binding PcG protein Pleiohomeotic (PHO). However, SCM is retained at this Ubx PRE despite genetic disruption or knockdown of PHO, PRC1, or PRC2, suggesting that SCM chromatin targeting does not require prior association of these other PcG components. Chromatin immunoprecipitations (IPs) to test the consequences of SCM genetic disruption or knockdown revealed that PHO association is unaffected, but reduced levels of PRE-bound PRC2 and PRC1 were observed. We discuss these results in light of current models for recruitment of PcG complexes to chromatin targets. PMID:20351181

  16. In the Pursuit of Sons: Additional Births or Sex-Selective Abortion in Pakistan?

    Science.gov (United States)

    Zaidi, Batool; Morgan, S Philip

    2016-12-01

    Even though Pakistan is a highly patriarchal society, it has not featured prominently in studies focusing on sex-selective abortion and sex ratios at birth. But with fertility declining and existing strong son preference-Pakistan has one of the highest desired sex ratios in the world-how will Pakistani families respond? In the pursuit of sons, will they have additional children or resort to sex-selective abortions? Or is there evidence that the pursuit of sons is weakening? Using data from three rounds of the demographic and health survey, we show clear evidence of son preference in fertility intentions, patterns of contraceptive use and parity progression ratios. More specifically, we find pervasive evidence that Pakistanis continue childbearing to have a son, to have more than one son and to have at least one daughter. We do not find consistent and convincing evidence that sex ratios at birth (which indicate sex-selective abortion) are increasing.

  17. Spectrally interleaved, comb-mode-resolved spectroscopy using swept dual terahertz combs

    Science.gov (United States)

    Hsieh, Yi-Da; Iyonaga, Yuki; Sakaguchi, Yoshiyuki; Yokoyama, Shuko; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Araki, Tsutomu; Yasui, Takeshi

    2014-01-01

    Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10-7 in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.

  18. Spectrally interleaved, comb-mode-resolved spectroscopy using swept dual terahertz combs.

    Science.gov (United States)

    Hsieh, Yi-Da; Iyonaga, Yuki; Sakaguchi, Yoshiyuki; Yokoyama, Shuko; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Araki, Tsutomu; Yasui, Takeshi

    2014-01-22

    Optical frequency combs are innovative tools for broadband spectroscopy because a series of comb modes can serve as frequency markers that are traceable to a microwave frequency standard. However, a mode distribution that is too discrete limits the spectral sampling interval to the mode frequency spacing even though individual mode linewidth is sufficiently narrow. Here, using a combination of a spectral interleaving and dual-comb spectroscopy in the terahertz (THz) region, we achieved a spectral sampling interval equal to the mode linewidth rather than the mode spacing. The spectrally interleaved THz comb was realized by sweeping the laser repetition frequency and interleaving additional frequency marks. In low-pressure gas spectroscopy, we achieved an improved spectral sampling density of 2.5 MHz and enhanced spectral accuracy of 8.39 × 10(-7) in the THz region. The proposed method is a powerful tool for simultaneously achieving high resolution, high accuracy, and broad spectral coverage in THz spectroscopy.

  19. Dynamics of microresonator frequency comb generation: models and stability

    Directory of Open Access Journals (Sweden)

    Hansson Tobias

    2016-06-01

    Full Text Available Microresonator frequency combs hold promise for enabling a new class of light sources that are simultaneously both broadband and coherent, and that could allow for a profusion of potential applications. In this article, we review various theoretical models for describing the temporal dynamics and formation of optical frequency combs. These models form the basis for performing numerical simulations that can be used in order to better understand the comb generation process, for example helping to identify the universal combcharacteristics and their different associated physical phenomena. Moreover, models allow for the study, design and optimization of comb properties prior to the fabrication of actual devices. We consider and derive theoretical formalisms based on the Ikeda map, the modal expansion approach, and the Lugiato-Lefever equation. We further discuss the generation of frequency combs in silicon resonators featuring multiphoton absorption and free-carrier effects. Additionally, we review comb stability properties and consider the role of modulational instability as well as of parametric instabilities due to the boundary conditions of the cavity. These instability mechanisms are the basis for comprehending the process of frequency comb formation, for identifying the different dynamical regimes and the associated dependence on the comb parameters. Finally, we also discuss the phenomena of continuous wave bi- and multistability and its relation to the observation of mode-locked cavity solitons.

  20. Laser Spectroscopy and Frequency Combs

    International Nuclear Information System (INIS)

    Hänsch, Theodor W; Picqué, Nathalie

    2013-01-01

    The spectrum of a frequency comb, commonly generated by a mode-locked femtosecond laser consists of several hundred thousand precisely evenly spaced spectral lines. Such laser frequency combs have revolutionized the art measuring the frequency of light, and they provide the long-missing clockwork for optical atomic clocks. The invention of the frequency comb technique has been motivated by precision laser spectroscopy of the simple hydrogen atom. The availability of commercial instruments is facilitating the evolution of new applications far beyond the original purpose. Laser combs are becoming powerful instruments for broadband molecular spectroscopy by dramatically improving the resolution and recording speed of Fourier spectrometers and by creating new opportunities for highly multiplexed nonlinear spectroscopy, such as two-photon spectroscopy or coherent Raman spectroscopy. Other emerging applications of frequency combs range from fundamental research in astronomy, chemistry, or attosecond science to telecommunications and satellite navigation

  1. Biological and Biomimetic Comb Polyelectrolytes

    Directory of Open Access Journals (Sweden)

    Aristeidis Papagiannopoulos

    2010-05-01

    Full Text Available Some new phenomena involved in the physical properties of comb polyelectrolyte solutions are reviewed. Special emphasis is given to synthetic biomimetic materials, and the structures formed by these molecules are compared with those of naturally occurring glycoprotein and proteoglycan solutions. Developments in the determination of the structure and dynamics (viscoelasticity of comb polymers in solution are also covered. Specifically the appearance of multi-globular structures, helical instabilities, liquid crystalline phases, and the self-assembly of the materials to produce hierarchical comb morphologies is examined. Comb polyelectrolytes are surface active and a short review is made of some recent experiments in this area that relate to their morphology when suspended in solution. We hope to emphasize the wide variety of phenomena demonstrated by the vast range of naturally occurring comb polyelectrolytes and the challenges presented to synthetic chemists designing biomimetic materials.

  2. Sub-lethal effects of pesticide residues in brood comb on worker honey bee (Apis mellifera development and longevity.

    Directory of Open Access Journals (Sweden)

    Judy Y Wu

    Full Text Available BACKGROUND: Numerous surveys reveal high levels of pesticide residue contamination in honey bee comb. We conducted studies to examine possible direct and indirect effects of pesticide exposure from contaminated brood comb on developing worker bees and adult worker lifespan. METHODOLOGY/PRINCIPAL FINDINGS: Worker bees were reared in brood comb containing high levels of known pesticide residues (treatment or in relatively uncontaminated brood comb (control. Delayed development was observed in bees reared in treatment combs containing high levels of pesticides particularly in the early stages (day 4 and 8 of worker bee development. Adult longevity was reduced by 4 days in bees exposed to pesticide residues in contaminated brood comb during development. Pesticide residue migration from comb containing high pesticide residues caused contamination of control comb after multiple brood cycles and provided insight on how quickly residues move through wax. Higher brood mortality and delayed adult emergence occurred after multiple brood cycles in contaminated control combs. In contrast, survivability increased in bees reared in treatment comb after multiple brood cycles when pesticide residues had been reduced in treatment combs due to residue migration into uncontaminated control combs, supporting comb replacement efforts. Chemical analysis after the experiment confirmed the migration of pesticide residues from treatment combs into previously uncontaminated control comb. CONCLUSIONS/SIGNIFICANCE: This study is the first to demonstrate sub-lethal effects on worker honey bees from pesticide residue exposure from contaminated brood comb. Sub-lethal effects, including delayed larval development and adult emergence or shortened adult longevity, can have indirect effects on the colony such as premature shifts in hive roles and foraging activity. In addition, longer development time for bees may provide a reproductive advantage for parasitic Varroa destructor

  3. Unilateral antler combs from Romuliana

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    Petković Sofija

    2006-01-01

    Full Text Available In the course of investigations at Romuliana nine antler three-partite combs with a single row of teeth were found in the Late Roman horizons dating from the late 4th - mid 5th century. They were found in Tower 19, in the Palace II sector and in the Thermae sector. The combs can be classified as two types: three-partite unilateral combs with semicircular handle (Petković comb type VII and three-partite unilateral combs with triangular handle decorated with horse protomes (Petković comb type VI. Two groups of these finds were distinguished after more detailed analysis; the earlier one including specimens originating from the Chernyahov-Sîntana de Mureº culture and later one including specimens made under "barbarian"influence and produced in Romuliana. These finds confirm the continuity of settlement at Romuliana in the Late Roman period, from the final quarter of the 4th until the end of the 5th century and open up the question of the character of the settlement.

  4. Comb-Resolved Dual-Comb Spectroscopy Stabilized by Free-Running Continuous-Wave Lasers

    Science.gov (United States)

    Kuse, Naoya; Ozawa, Akira; Kobayashi, Yohei

    2012-11-01

    We demonstrate dual-comb spectroscopy with relatively phase-locked two frequency combs, instead of frequency combs firmly fixed to the absolute frequency references. By stabilizing two beat frequencies between two mode-locked lasers at different wavelengths observed via free-running continuous-wave (CW) lasers, two combs are tightly phase locked to each other. The frequency noise of the CW lasers barely affects the performance of dual-comb spectroscopy because of the extremely fast common-mode noise rejection. Transform-limited comb-resolved dual-comb spectroscopy with a 6 Hz radio frequency linewidth is demonstrated by the use of Yb-fiber oscillators.

  5. Molecular Combing of DNA: Methods and Applications

    DEFF Research Database (Denmark)

    Nazari, Zeniab Esmail; Gurevich, Leonid

    2013-01-01

    studies to nanoelectronics. While molecular combing has been applied in a variety of DNA-related studies, no comprehensive review has been published on different combing methods proposed so far. In this review, the underlying mechanisms of molecular combing of DNA are described followed by discussion...

  6. Schizocordulia gen. nov. related to Aeschnosom Selys with description of the female and additional data on the male of Schizocordulia rustica (Selys comb. nov. (Odonata, Corduliidae Schizocordulia gen. nov. relacionado a Aeschnosoma Selys com descrição da fêmea e dados adicionais sobre o macho de Schizocordulia rustica (Selys comb. nov. (Odonata, Corduliidae

    Directory of Open Access Journals (Sweden)

    Angelo B.M. Machado

    2005-09-01

    Full Text Available The monotypical genus Schizocordulia is created for Schizocordulia rustica (Selys, 1871 comb. nov. known from a single male from Bahia, Brazil lacking the anal appendages. The female is described and the redescription of the male made by GEIJKES (1970 is completed by the description and illustration of the penis, the anal appendages and the pilose plate. The main characters separating the new genus from the closely related Aeschnosoma Selys, 1870 are the bifid male inferior appendage, the very long internal branch of the hamulus, the presence of a pilose plate on the male 7th abdominal segment, and the large and complex valvula vulvae of the female. The study was based on 33 males and 2 females, which allowed an evaluation of the intraspecific variations in Schizocordulia rustica.Cria-se o gênero monotípico Schizocordulia para Schizocordulia rustica (Selys, 1871 comb. nov. espécie conhecida de um único exemplar macho sem os apêndices anais. Descreve-se a fêmea e a redescrição do macho feita por GEIJKES (1970 é completada pela descrição e ilustração do pênis, da placa pilosa e dos apêndices anais. Os principais caracteres utilizados para separar Schizocordulia do gênero afim Aeschnosoma Selys, 1870 são o apêndice inferior do macho bífido, o ramo interno do hâmulo muito longo, a presença de uma placa pilosa no 7º segmento abdominal e a válvula da vulva da fêmea grande e complexa. Este estudo foi baseado em 33 machos e 2 fêmeas, o que permitiu uma avaliação das variações intraespecíficas em Schizocordulia rustica.

  7. On Frequency Combs in Monolithic Resonators

    Directory of Open Access Journals (Sweden)

    Savchenkov A. A.

    2016-06-01

    Full Text Available Optical frequency combs have become indispensable in astronomical measurements, biological fingerprinting, optical metrology, and radio frequency photonic signal generation. Recently demonstrated microring resonator-based Kerr frequency combs point the way towards chip scale optical frequency comb generator retaining major properties of the lab scale devices. This technique is promising for integrated miniature radiofrequency and microwave sources, atomic clocks, optical references and femtosecond pulse generators. Here we present Kerr frequency comb development in a historical perspective emphasizing its similarities and differences with other physical phenomena. We elucidate fundamental principles and describe practical implementations of Kerr comb oscillators, highlighting associated solved and unsolved problems.

  8. On Frequency Combs in Monolithic Resonators

    Science.gov (United States)

    Savchenkov, A. A.; Matsko, A. B.; Maleki, L.

    2016-06-01

    Optical frequency combs have become indispensable in astronomical measurements, biological fingerprinting, optical metrology, and radio frequency photonic signal generation. Recently demonstrated microring resonator-based Kerr frequency combs point the way towards chip scale optical frequency comb generator retaining major properties of the lab scale devices. This technique is promising for integrated miniature radiofrequency and microwave sources, atomic clocks, optical references and femtosecond pulse generators. Here we present Kerr frequency comb development in a historical perspective emphasizing its similarities and differences with other physical phenomena. We elucidate fundamental principles and describe practical implementations of Kerr comb oscillators, highlighting associated solved and unsolved problems.

  9. Concentration addition, independent action and generalized concentration addition models for mixture effect prediction of sex hormone synthesis in vitro.

    Directory of Open Access Journals (Sweden)

    Niels Hadrup

    Full Text Available Humans are concomitantly exposed to numerous chemicals. An infinite number of combinations and doses thereof can be imagined. For toxicological risk assessment the mathematical prediction of mixture effects, using knowledge on single chemicals, is therefore desirable. We investigated pros and cons of the concentration addition (CA, independent action (IA and generalized concentration addition (GCA models. First we measured effects of single chemicals and mixtures thereof on steroid synthesis in H295R cells. Then single chemical data were applied to the models; predictions of mixture effects were calculated and compared to the experimental mixture data. Mixture 1 contained environmental chemicals adjusted in ratio according to human exposure levels. Mixture 2 was a potency adjusted mixture containing five pesticides. Prediction of testosterone effects coincided with the experimental Mixture 1 data. In contrast, antagonism was observed for effects of Mixture 2 on this hormone. The mixtures contained chemicals exerting only limited maximal effects. This hampered prediction by the CA and IA models, whereas the GCA model could be used to predict a full dose response curve. Regarding effects on progesterone and estradiol, some chemicals were having stimulatory effects whereas others had inhibitory effects. The three models were not applicable in this situation and no predictions could be performed. Finally, the expected contributions of single chemicals to the mixture effects were calculated. Prochloraz was the predominant but not sole driver of the mixtures, suggesting that one chemical alone was not responsible for the mixture effects. In conclusion, the GCA model seemed to be superior to the CA and IA models for the prediction of testosterone effects. A situation with chemicals exerting opposing effects, for which the models could not be applied, was identified. In addition, the data indicate that in non-potency adjusted mixtures the effects cannot

  10. A Josephson radiation comb generator.

    Science.gov (United States)

    Solinas, P; Gasparinetti, S; Golubev, D; Giazotto, F

    2015-07-20

    We propose the implementation of a Josephson Radiation Comb Generator (JRCG) based on a dc superconducting quantum interference device (SQUID) driven by an external magnetic field. When the magnetic flux crosses a diffraction node of the critical current interference pattern, the superconducting phase undergoes a jump of π and a voltage pulse is generated at the extremes of the SQUID. Under periodic drive this allows one to generate a sequence of sharp, evenly spaced voltage pulses. In the frequency domain, this corresponds to a comb-like structure similar to the one exploited in optics and metrology. With this device it is possible to generate up to several hundreds of harmonics of the driving frequency. For example, a chain of 50 identical high-critical-temperature SQUIDs driven at 1 GHz can deliver up to a 0.5 nW at 200 GHz. The availability of a fully solid-state radiation comb generator such as the JRCG, easily integrable on chip, may pave the way to a number of technological applications, from metrology to sub-millimeter wave generation.

  11. Taxonomic evaluation of the genus Enterobacter based on multilocus sequence analysis (MLSA): proposal to reclassify E. nimipressuralis and E. amnigenus into Lelliottia gen. nov. as Lelliottia nimipressuralis comb. nov. and Lelliottia amnigena comb. nov., respectively, E. gergoviae and E. pyrinus into Pluralibacter gen. nov. as Pluralibacter gergoviae comb. nov. and Pluralibacter pyrinus comb. nov., respectively, E. cowanii, E. radicincitans, E. oryzae and E. arachidis into Kosakonia gen. nov. as Kosakonia cowanii comb. nov., Kosakonia radicincitans comb. nov., Kosakonia oryzae comb. nov. and Kosakonia arachidis comb. nov., respectively, and E. turicensis, E. helveticus and E. pulveris into Cronobacter as Cronobacter zurichensis nom. nov., Cronobacter helveticus comb. nov. and Cronobacter pulveris comb. nov., respectively, and emended description of the genera Enterobacter and Cronobacter.

    Science.gov (United States)

    Brady, Carrie; Cleenwerck, Ilse; Venter, Stephanus; Coutinho, Teresa; De Vos, Paul

    2013-07-01

    The taxonomy of Enterobacter has a complicated history, with several species transferred to and from this genus. Classification of strains is difficult owing to its polyphyletic nature, based on 16S rRNA gene sequences. It has been previously acknowledged that Enterobacter contains species which should be transferred to other genera. In an attempt to resolve the taxonomy of Enterobacter, MLSA based on partial sequencing of protein-encoding genes (gyrB, rpoB, infB and atpD) was performed on the type strains and reference strains of Enterobacter, Cronobacter and Serratia species, as well as members of the closely related genera Citrobacter, Klebsiella, Kluyvera, Leclercia, Mangrovibacter, Raoultella and Yokenella. Phylogenetic analyses of the concatenated nucleotide sequences revealed that Enterobacter can be divided into five strongly supported MLSA groups, suggesting that the species should be reclassified into five different genera. Further support for this was provided by a concatenated amino acid tree, phenotypic characteristics and fatty acid profiles, enabling differentiation of the MLSA groups. Three novel genera are proposed: Lelliottia gen. nov., Pluralibacter gen. nov. and Kosakonia gen. nov. and the following new combinations: Lelliottia nimipressuralis comb. nov., Lelliottia amnigena comb. nov., Pluralibacter gergoviae comb. nov., Pluralibacter pyrinus comb. nov., Kosakonia cowanii comb. nov., Kosakonia radicincitans comb. nov., Kosakonia oryzae comb. nov., Kosakonia arachidis comb. nov., Cronobacter helveticus comb. nov. and Cronobacter pulveris comb. nov. Additionally, the novel epithet Cronobacter zurichensis nom. nov. is proposed for the reclassification of Enterobacter turicensis into the genus Cronobacter, as Cronobacter turicensis (Iversen et al., 2008) is already in use. Copyright © 2013 Elsevier GmbH. All rights reserved.

  12. Normal-dispersion microresonator Kerr frequency combs

    Directory of Open Access Journals (Sweden)

    Xue Xiaoxiao

    2016-06-01

    Full Text Available Optical microresonator-based Kerr frequency comb generation has developed into a hot research area in the past decade. Microresonator combs are promising for portable applications due to their potential for chip-level integration and low power consumption. According to the group velocity dispersion of the microresonator employed, research in this field may be classified into two categories: the anomalous dispersion regime and the normal dispersion regime. In this paper, we discuss the physics of Kerr comb generation in the normal dispersion regime and review recent experimental advances. The potential advantages and future directions of normal dispersion combs are also discussed.

  13. Analysis on characteristic and application of THz frequency comb and THz sub-comb

    International Nuclear Information System (INIS)

    Liu Pengxiang; Xu Degang; Yao Jianquan

    2011-01-01

    In this paper, we proposed a method for THz sub-comb generation based on spectral interference. The result of our calculation indicated that the THz pulse train, generated by surface-emitted optical rectification of femtosecond (fs) laser pulse in periodically poled lithium niobate (PPLN), has a comb-like spectrum. The characteristic of this THz sub-comb was analyzed both in frequency and time domain. Compared with the THz frequency comb emitted by a photoconductive antenna (PCA), THz sub-comb has a lower spectral resolution and wider free spectral range. Thus it could be an ideal source for wavelength division multiplexing (WDM) in THz wireless communication system.

  14. Automation and semantics: the CombeChem experience

    OpenAIRE

    Frey, Jeremy G.

    2004-01-01

    Some of the experiences of the CombeChem e-Science project in relation to both automation and the need for semantics in combining modern computer science techniques and chemistry are discussed. In particular the aspects of the smart laboratory, large scale data handling and the way this impacts on the necessary database technology are discussed. In addition some of the ways in which the grid can enable greater user interaction with services such as the National Crystallography Service and imp...

  15. A bidirectional dual-comb ring laser for simple and robust dual-comb spectroscopy

    OpenAIRE

    Ideguchi, Takuro; Nakamura, Tasuku; Kobayashi, Yohei; Goda, Keisuke

    2015-01-01

    Fourier-transform spectroscopy is an indispensable tool for analyzing chemical samples in scientific research as well as chemical and pharmaceutical industries. Recently, its measurement speed, sensitivity, and precision have been shown to be significantly enhanced by using dual frequency combs. However, wide acceptance of this technique is hindered by its requirement for two frequency combs and active stabilization of the combs. Here we overcome this predicament with a Kerr-lens mode-locked ...

  16. Cantharellus gallaecicus (Blanco-Dios Olariaga, comb. & stat. nov (Cantharellaceae

    Directory of Open Access Journals (Sweden)

    Olariaga, Ibai

    2007-12-01

    Full Text Available Cantharellus gallaecicus comb. & stat. nov. is proposed, after the examination of its holotype and additional material. Based on the characters observed in all the studied material (i.e., thinwalled hyphae of the pileipelis, minute basidiomata with white to grey pileus, and surface that turns yellow when bruised it is considered that C. gallaecicus is more closely related to C. romagnesianus than to C. cibarius.Se propone Cantharellus gallaecicus comb. & stat. nov. tras revisar su holótipo y material adicional disponible. Dado que todo el material examinado posee hifas del pileipelis de pared delgada, basidiomas pequeños con píleo de blanco a gris, y superficie que vira a amarillo al roce, se considera que C. gallaecicus es una especie más estrechamente relacionada con C. romagnesianus que con C. cibarius.

  17. Frequency-agile dual-comb spectroscopy

    OpenAIRE

    Millot, Guy; Pitois, Stéphane; Yan, Ming; Hovannysyan, Tatevik; Bendahmane, Abdelkrim; Hänsch, Theodor W.; Picqué, Nathalie

    2015-01-01

    We propose a new approach to near-infrared molecular spectroscopy, harnessing advanced concepts of optical telecommunications and supercontinuum photonics. We generate, without mode-locked lasers, two frequency combs of slightly different repetition frequencies and moderate, but rapidly tunable, spectral span. The output of a frequency-agile continuous wave laser is split and sent into two electro-optic intensity modulators. Flat-top low-noise frequency combs are produced by wave-breaking in ...

  18. George Combe and common sense.

    Science.gov (United States)

    Dyde, Sean

    2015-06-01

    This article examines the history of two fields of enquiry in late eighteenth- and early nineteenth-century Scotland: the rise and fall of the common sense school of philosophy and phrenology as presented in the works of George Combe. Although many previous historians have construed these histories as separate, indeed sometimes incommensurate, I propose that their paths were intertwined to a greater extent than has previously been given credit. The philosophy of common sense was a response to problems raised by Enlightenment thinkers, particularly David Hume, and spurred a theory of the mind and its mode of study. In order to succeed, or even to be considered a rival of these established understandings, phrenologists adapted their arguments for the sake of engaging in philosophical dispute. I argue that this debate contributed to the relative success of these groups: phrenology as a well-known historical subject, common sense now largely forgotten. Moreover, this history seeks to question the place of phrenology within the sciences of mind in nineteenth-century Britain.

  19. Laboratory duplication of comb layering in the Rhum pluton. [igneous rocks with comb layered texture

    Science.gov (United States)

    Donaldson, C. H.

    1977-01-01

    A description is provided of the texture of harrisite comb layers, taking into account the results of crystallization experiments at controlled cooling rates, which have reproduced the textural change from 'cumulate' to comb-layered harrisite. Melted samples of harrisite were used in the dynamic crystallization experiments considered. The differentiation of a cooling rate run with respect to olivine grain size and shape is shown and three possible origins of hopper olivine in differentiated crystallization runs are considered. It is found that olivine nucleation occurred throughout cooling, except for the incubation period during early cooling. The elongate combed olivines in harrisite apparently grew as the magma locally supercooled to at least 30 C. It is suggested that the branching crystals in most comb layers, including comb-layered harrisite, probably grew along thermal gradients.

  20. Frequency comb generation in a continuously pumped optical parametric oscillator

    Science.gov (United States)

    Mosca, S.; Parisi, M.; Ricciardi, I.; Leo, F.; Hansson, T.; Erkintalo, M.; Maddaloni, P.; De Natale, P.; Wabnitz, S.; De Rosa, M.

    2018-02-01

    We demonstrate optical frequency comb generation in a continuously pumped optical parametric oscillator, in the parametric region around half of the pump frequency. We also model the dynamics of such quadratic combs using a single time-domain mean-field equation, and obtain simulation results that are in good agreement with experimentally observed spectra. Moreover, we numerically investigate the coherence properties of simulated combs, showing the existence of correlated and phase-locked combs. Our work could pave the way for a new class of frequency comb sources, which may enable straightforward access to new spectral regions and stimulate novel applications of frequency combs.

  1. Sonic Hedgehog-signalling patterns the developing chicken comb as revealed by exploration of the pea-comb mutation.

    Directory of Open Access Journals (Sweden)

    Henrik Boije

    Full Text Available The genetic basis and mechanisms behind the morphological variation observed throughout the animal kingdom is still relatively unknown. In the present work we have focused on the establishment of the chicken comb-morphology by exploring the Pea-comb mutant. The wild-type single-comb is reduced in size and distorted in the Pea-comb mutant. Pea-comb is formed by a lateral expansion of the central comb anlage into three ridges and is caused by a mutation in SOX5, which induces ectopic expression of the SOX5 transcription factor in mesenchyme under the developing comb. Analysis of differential gene expression identified decreased Sonic hedgehog (SHH receptor expression in Pea-comb mesenchyme. By experimentally blocking SHH with cyclopamine, the wild-type single-comb was transformed into a Pea-comb-like phenotype. The results show that the patterning of the chicken comb is under the control of SHH and suggest that ectopic SOX5 expression in the Pea-comb change the response of mesenchyme to SHH signalling with altered comb morphogenesis as a result. A role for the mesenchyme during comb morphogenesis is further supported by the recent finding that another comb-mutant (Rose-comb, is caused by ectopic expression of a transcription factor in comb mesenchyme. The present study does not only give knowledge about how the chicken comb is formed, it also adds to our understanding how mutations or genetic polymorphisms may contribute to inherited variations in the human face.

  2. Direct Frequency Comb Spectroscopy of Alkali Atoms

    Science.gov (United States)

    Pradhananga, Trinity; Palm, Christopher; Nguyen, Khoa; Guttikonda, Srikanth; Kimball, Derek Jackson

    2011-11-01

    We are using direct frequency comb spectroscopy to study transition frequencies and excited state hyperfine structure in potassium and rubidium using 2-photon transitions excited directly with the frequency-doubled output of a erbium fiber optical frequency comb. The frequency comb output is directed in two counterpropagating directions through a vapor cell containing the atomic vapor of interest. A pair of optical filters is used to select teeth of the comb in order to identify the transition wavelengths. A photomultiplier tube (PMT) measures fluorescence from a decay channel wavelength selected with another optical filter. Using different combinations of filters enables a wide range of transitions to be investigated. By scanning the repetition rate, a Doppler-free spectrum can be obtained enabling kHz-resolution spectral measurements. The thermal motion of the atoms in the vapor cell actually eliminates the need to fine-tune the offset frequency and repetition rate, alleviating a somewhat challenging requirement for spectroscopy of cold atoms. Our investigations are laying the groundwork for a long-term research program to use direct frequency comb spectroscopy to understand the complex spectra of rare-earth atoms.

  3. Microresonator soliton dual-comb spectroscopy

    Science.gov (United States)

    Suh, Myoung-Gyun; Yang, Qi-Fan; Yang, Ki Youl; Yi, Xu; Vahala, Kerry J.

    2016-11-01

    Measurement of optical and vibrational spectra with high resolution provides a way to identify chemical species in cluttered environments and is of general importance in many fields. Dual-comb spectroscopy has emerged as a powerful approach for acquiring nearly instantaneous Raman and optical spectra with unprecedented resolution. Spectra are generated directly in the electrical domain, without the need for bulky mechanical spectrometers. We demonstrate a miniature soliton-based dual-comb system that can potentially transfer the approach to a chip platform. These devices achieve high-coherence pulsed mode locking. They also feature broad, reproducible spectral envelopes, an essential feature for dual-comb spectroscopy. Our work shows the potential for integrated spectroscopy with high signal-to-noise ratios and fast acquisition rates.

  4. On-chip dual comb source for spectroscopy

    OpenAIRE

    Dutt, Avik; Joshi, Chaitanya; Ji, Xingchen; Cardenas, Jaime; Okawachi, Yoshitomo; Luke, Kevin; Gaeta, Alexander L.; Lipson, Michal

    2016-01-01

    Dual-comb spectroscopy is a powerful technique for real-time, broadband optical sampling of molecular spectra which requires no moving components. Recent developments with microresonator-based platforms have enabled frequency combs at the chip scale. However, the need to precisely match the resonance wavelengths of distinct high-quality-factor microcavities has hindered the development of an on-chip dual comb source. Here, we report the first simultaneous generation of two microresonator comb...

  5. Time sequence photography of Roosters Comb

    Science.gov (United States)

    The importance of understanding natural landscape changes is key in properly determining rangeland ecology. Time sequence photography allows a landscape snapshot to be documented and enables the ability to compare natural changes overtime. Photographs of Roosters Comb were taken from the same vantag...

  6. Comb-drive actuators for large displacements

    NARCIS (Netherlands)

    Legtenberg, Rob; Legtenberg, R.; Groeneveld, A.W.; Elwenspoek, Michael Curt

    The design, fabrication and experimental results of lateral-comb-drive actuators for large displacements at low driving voltages is presented. A comparison of several suspension designs is given, and the lateral large deflection behaviour of clamped-clamped beams and a folded flexure design is

  7. Stochastic transport through complex comb structures

    International Nuclear Information System (INIS)

    Zaburdaev, V. Yu.; Popov, P. V.; Romanov, A. S.; Chukbar, K. V.

    2008-01-01

    A unified rigorous approach is used to derive fractional differential equations describing subdiffusive transport through comb structures of various geometrical complexity. A general nontrivial effect of the initial particle distribution on the subsequent evolution is exposed. Solutions having qualitative features of practical importance are given for joined structures with widely different fractional exponents

  8. Dissemination of optical-comb-based ultra-broadband frequency reference through a fiber network.

    Science.gov (United States)

    Nagano, Shigeo; Kumagai, Motohiro; Li, Ying; Ido, Tetsuya; Ishii, Shoken; Mizutani, Kohei; Aoki, Makoto; Otsuka, Ryohei; Hanado, Yuko

    2016-08-22

    We disseminated an ultra-broadband optical frequency reference based on a femtosecond (fs)-laser optical comb through a kilometer-scale fiber link. Its spectrum ranged from 1160 nm to 2180 nm without additional fs-laser combs at the end of the link. By employing a fiber-induced phase noise cancellation technique, the linewidth and fractional frequency instability attained for all disseminated comb modes were of order 1 Hz and 10-18 in a 5000 s averaging time. The ultra-broad optical frequency reference, for which absolute frequency is traceable to Japan Standard Time, was applied in the frequency stabilization of an injection-seeded Q-switched 2051 nm pulse laser for a coherent light detection and ranging LIDAR system.

  9. Inter-comb synchronization by mode-to-mode locking

    Science.gov (United States)

    Chun, Byung Jae; Kim, Young-Jin; Kim, Seung-Woo

    2016-08-01

    Two combs of fiber femtosecond lasers are synchronized through the optical frequency reference created by injection-locking of a diode laser to a single comb mode. Maintaining a mHz-level narrow linewidth, the optical frequency reference permits two combs to be stabilized by mode-to-mode locking with a relative stability of 1.52  ×  10-16 at 10 s with a frequency slip of 2.46 mHz. This inter-comb synchronization can be utilized for applications such as dual-comb spectroscopy or ultra-short pulse synthesis without extra narrow-linewidth lasers.

  10. Optical frequency comb generation based on the dual-mode square microlaser and a nonlinear fiber loop

    Science.gov (United States)

    Weng, Hai-Zhong; Han, Jun-Yuan; Li, Qing; Yang, Yue-De; Xiao, Jin-Long; Qin, Guan-Shi; Huang, Yong-Zhen

    2018-05-01

    A novel approach using a dual-mode square microlaser as the pump source is demonstrated to produce wideband optical frequency comb (OFC). The enhanced nonlinear frequency conversion processes are accomplished in a nonlinear fiber loop, which can reduce the stimulated Brillouin scattering threshold and then generate a dual-mode Brillouin laser with improved optical signal-to-noise ratio. An OFC with 130 nm bandwidth and 76 GHz repetition rate is successfully generated under the four-wave mixing, and the number of the comb lines is enhanced by 26 times compared with the system without fiber loop. In addition, the repetition rate of the comb can be adjusted by changing the injection current of the microlaser. The pulse width of the comb spectrum is also compressed from 3 to 1 ps with an extra amplification-nonlinear process.

  11. Phase separation of comb polymer nanocomposite melts.

    Science.gov (United States)

    Xu, Qinzhi; Feng, Yancong; Chen, Lan

    2016-02-07

    In this work, the spinodal phase demixing of branched comb polymer nanocomposite (PNC) melts is systematically investigated using the polymer reference interaction site model (PRISM) theory. To verify the reliability of the present method in characterizing the phase behavior of comb PNCs, the intermolecular correlation functions of the system for nonzero particle volume fractions are compared with our molecular dynamics simulation data. After verifying the model and discussing the structure of the comb PNCs in the dilute nanoparticle limit, the interference among the side chain number, side chain length, nanoparticle-monomer size ratio and attractive interactions between the comb polymer and nanoparticles in spinodal demixing curves is analyzed and discussed in detail. The results predict two kinds of distinct phase separation behaviors. One is called classic fluid phase boundary, which is mediated by the entropic depletion attraction and contact aggregation of nanoparticles at relatively low nanoparticle-monomer attraction strength. The second demixing transition occurs at relatively high attraction strength and involves the formation of an equilibrium physical network phase with local bridging of nanoparticles. The phase boundaries are found to be sensitive to the side chain number, side chain length, nanoparticle-monomer size ratio and attractive interactions. As the side chain length is fixed, the side chain number has a large effect on the phase behavior of comb PNCs; with increasing side chain number, the miscibility window first widens and then shrinks. When the side chain number is lower than a threshold value, the phase boundaries undergo a process from enlarging the miscibility window to narrowing as side chain length increases. Once the side chain number overtakes this threshold value, the phase boundary shifts towards less miscibility. With increasing nanoparticle-monomer size ratio, a crossover of particle size occurs, above which the phase separation

  12. Dual frequency comb metrology with one fiber laser

    Science.gov (United States)

    Zhao, Xin; Takeshi, Yasui; Zheng, Zheng

    2016-11-01

    Optical metrology techniques based on dual optical frequency combs have emerged as a hotly studied area targeting a wide range of applications from optical spectroscopy to microwave and terahertz frequency measurement. Generating two sets of high-quality comb lines with slightly different comb-tooth spacings with high mutual coherence and stability is the key to most of the dual-comb schemes. The complexity and costs of such laser sources and the associated control systems to lock the two frequency combs hinder the wider adoption of such techniques. Here we demonstrate a very simple and rather different approach to tackle such a challenge. By employing novel laser cavity designs in a mode-locked fiber laser, a simple fiber laser setup could emit dual-comb pulse output with high stability and good coherence between the pulse trains. Based on such lasers, comb-tooth-resolved dual-comb optical spectroscopy is demonstrated. Picometer spectral resolving capability could be realized with a fiber-optic setup and a low-cost data acquisition system and standard algorithms. Besides, the frequency of microwave signals over a large range can be determined based on a simple setup. Our results show the capability of such single-fiber-laser-based dual-comb scheme to reduce the complexity and cost of dual-comb systems with excellent quality for different dual-comb applications.

  13. Aerodynamics of a translating comb-like plate inspired by a fairyfly wing

    Science.gov (United States)

    Lee, Seung Hun; Kim, Daegyoum

    2017-08-01

    Unlike the smooth wings of common insects or birds, micro-scale insects such as the fairyfly have a distinctive wing geometry, comprising a frame with several bristles. Motivated by this peculiar wing geometry, we experimentally investigated the flow structure of a translating comb-like wing for a wide range of gap size, angle of attack, and Reynolds number, Re = O(10) - O(103), and the correlation of these parameters with aerodynamic performance. The flow structures of a smooth plate without a gap and a comb-like plate are significantly different at high Reynolds number, while little difference was observed at the low Reynolds number of O(10). At low Reynolds number, shear layers that were generated at the edges of the tooth of the comb-like plate strongly diffuse and eventually block a gap. This gap blockage increases the effective surface area of the plate and alters the formation of leading-edge and trailing-edge vortices. As a result, the comb-like plate generates larger aerodynamic force per unit area than the smooth plate. In addition to a quasi-steady phase after the comb-like plate travels several chords, we also studied a starting phase of the shear layer development when the comb-like plate begins to translate from rest. While a plate with small gap size can generate aerodynamic force at the starting phase as effectively as at the quasi-steady phase, the aerodynamic force drops noticeably for a plate with a large gap because the diffusion of the developing shear layers is not enough to block the gap.

  14. Femtosecond optical parametric oscillators toward real-time dual-comb spectroscopy

    Science.gov (United States)

    Jin, Yuwei; Cristescu, Simona M.; Harren, Frans J. M.; Mandon, Julien

    2015-04-01

    We demonstrate mid-infrared dual-comb spectroscopy with an optical parametric oscillator (OPO) toward real-time field measurement. A singly resonant OPO based on a MgO-doped periodically poled lithium niobate (PPLN) crystal is demonstrated. Chirped mirrors are used to compensate the dispersion caused by the optical cavity and the crystal. A low threshold of 17 mW has been achieved. The OPO source generates a tunable idler frequency comb between 2.7 and 4.7 μm. Dual-comb spectroscopy is achieved by coupling two identical Yb-fiber mode-locked lasers to this OPO with slightly different repetition frequencies. A measured absorption spectrum of methane is presented with a spectral bandwidth of , giving an instrumental resolution of . In addition, a second OPO containing two MgO-doped PPLN crystals in a singly resonant ring cavity is demonstrated. As such, this OPO generates two idler combs (average power up to 220 mW), covering a wavelength range between 2.7 and 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyned signal between the two idler combs, broadband spectra of molecular gases can be observed over a spectral bandwidth of more than . This special cavity design allows the spectral resolution to be improved to without locking the OPO cavity, indicating that this OPO represents an ideal high-power broadband mid-infrared source for real-time gas sensing.

  15. Patterns of comb row development in young and adult stages of the ctenophores Mnemiopsis leidyi and Pleurobrachia pileus.

    Science.gov (United States)

    Tamm, Sidney L

    2012-09-01

    ciliary coordination. In both cases, the body of a growing ctenophore is supplied with additional comb plates centripetally from opposite ends of the comb rows. Copyright © 2012 Wiley Periodicals, Inc.

  16. Enhanced post wash retention of combed DNA molecules by varying multiple combing parameters.

    Science.gov (United States)

    Yadav, Hemendra; Sharma, Pulkit

    2017-11-01

    Recent advances in genomics have created a need for efficient techniques for deciphering information hidden in various genomes. Single molecule analysis is one such technique to understand molecular processes at single molecule level. Fiber- FISH performed with the help of DNA combing can help us in understanding genetic rearrangements and changes in genome at single DNA molecule level. For performing Fiber-FISH we need high retention of combed DNA molecules post wash as Fiber-FISH requires profuse washing. We optimized combing process involving combing solution, method of DNA mounting on glass slides and coating of glass slides to enhance post-wash retention of DNA molecules. It was found that average number of DNA molecules observed post-wash per field of view was maximum with our optimized combing solution. APTES coated glass slides showed lesser retention than PEI surface but fluorescent intensity was higher in case of APTES coated surface. Capillary method used to mount DNA on glass slides also showed lesser retention but straight DNA molecules were observed as compared to force flow method. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Mesoscopic description of random walks on combs

    Science.gov (United States)

    Méndez, Vicenç; Iomin, Alexander; Campos, Daniel; Horsthemke, Werner

    2015-12-01

    Combs are a simple caricature of various types of natural branched structures, which belong to the category of loopless graphs and consist of a backbone and branches. We study continuous time random walks on combs and present a generic method to obtain their transport properties. The random walk along the branches may be biased, and we account for the effect of the branches by renormalizing the waiting time probability distribution function for the motion along the backbone. We analyze the overall diffusion properties along the backbone and find normal diffusion, anomalous diffusion, and stochastic localization (diffusion failure), respectively, depending on the characteristics of the continuous time random walk along the branches, and compare our analytical results with stochastic simulations.

  18. Active Comb Filter Using Operational Transconductance Amplifier

    Directory of Open Access Journals (Sweden)

    Rajeev Kumar Ranjan

    2014-01-01

    Full Text Available A new approach for the design of an active comb filter is proposed to remove the selected frequencies of various signals. The proposed filter is based on only OTAs and capacitors, hence suitable for monolithic integrated circuit implementation. The workability of the circuit is tested using PSPICE for test signals of 60, 180, 300, and 420 Hz as in ECG signal. The results are given in the paper and found to agree well with theory.

  19. Silicon-Chip-Based Optical Frequency Combs

    Science.gov (United States)

    2015-10-26

    fiber-based polarization controllers and a polarization beam splitter , and the output power is monitored with a sensitive photodiode. We use a...a single CW laser beam coupled to a microresonators can produce stabilized, octave-spanning combs through highly cascaded four-wave mixing (FWM...resonator designs , the resonator and the coupling waveguide are monolithically integrated. Thus, the entire on-chip configuration of CMOS-compatible

  20. Dense electro-optic frequency comb generated by two-stage modulation for dual-comb spectroscopy.

    Science.gov (United States)

    Wang, Shuai; Fan, Xinyu; Xu, Bingxin; He, Zuyuan

    2017-10-01

    An electro-optic frequency comb enables frequency-agile comb-based spectroscopy without using sophisticated phase-locking electronics. Nevertheless, dense electro-optic frequency combs over broad spans have yet to be developed. In this Letter, we propose a straightforward and efficient method for electro-optic frequency comb generation with a small line spacing and a large span. This method is based on two-stage modulation: generating an 18 GHz line-spacing comb at the first stage and a 250 MHz line-spacing comb at the second stage. After generating an electro-optic frequency comb covering 1500 lines, we set up an easily established mutually coherent hybrid dual-comb interferometer, which combines the generated electro-optic frequency comb and a free-running mode-locked laser. As a proof of concept, this hybrid dual-comb interferometer is used to measure the absorption and dispersion profiles of the molecular transition of H 13 CN with a spectral resolution of 250 MHz.

  1. Frequency-agile dual-comb spectroscopy

    Science.gov (United States)

    Millot, Guy; Pitois, Stéphane; Yan, Ming; Hovhannisyan, Tatevik; Bendahmane, Abdelkrim; Hänsch, Theodor W.; Picqué, Nathalie

    2016-01-01

    Spectroscopic gas sensing and its applications to, for example, trace detection or chemical kinetics, require ever more demanding measurement times, acquisition rates, sensitivities, precisions and broad tuning ranges. Here, we propose a new approach to near-infrared molecular spectroscopy, utilizing advanced concepts of optical telecommunications and supercontinuum photonics. We generate, without mode-locked lasers, two frequency combs of slightly different repetition frequencies and moderate, but rapidly tunable, spectral span. The output of a frequency-agile continuous-wave laser is split and sent into two electro-optic intensity modulators. Flat-top low-noise frequency combs are produced by wave-breaking in a nonlinear optical fibre of normal dispersion. With a dual-comb spectrometer, we record Doppler-limited spectra spanning 60 GHz within 13 μs and an 80 kHz refresh rate, at a tuning speed of 10 nm s-1. The sensitivity for weak absorption is enhanced by a long gas-filled hollow-core fibre. New opportunities for real-time diagnostics may be opened up, even outside the laboratory.

  2. The additive effects of depressive symptoms and polysubstance use on HIV risk among gay, bisexual, and other men who have sex with men.

    Science.gov (United States)

    Card, Kiffer G; Lachowsky, Nathan J; Armstrong, Heather L; Cui, Zishan; Wang, Lu; Sereda, Paul; Jollimore, Jody; Patterson, Thomas L; Corneil, Trevor; Hogg, Robert S; Roth, Eric A; Moore, David M

    2018-07-01

    Among gay, bisexual, and other men who have sex with men (GBM), collinearity between polysubstance use and mental health concerns has obscured their combined effects on HIV risk with multivariable results often highlighting only one or the other. We used mediation and moderation analyses to examine the effects of polysubstance use and depressive symptoms on high-risk sex (i.e., condomless anal sex with serodiscordant/unknown status partner) in a sample of sexually-active GBM, aged ≥16 years, recruited in Metro Vancouver using respondent driven sampling. Hospital Anxiety and Depression Scale scores assessed mental health. Alcohol Use Disorder Identification Test scores assessed alcohol disorders. Poly-use of multiple drug types (e.g., stimulants, sedatives, opiates, hallucinogens) was assessed over the previous six months. Among 719 predominantly white (68.0%), gay-identified (80.7%) GBM, alcohol use was not associated with increased prevalence of high-risk sex. Controlling for demographic factors and partner number, an interaction between polysubstance use and depressive symptoms revealed that the combined effects were additively associated with increased odds for high-risk sex. Mediation models showed that polysubstance use partially mediated the relationship between depressive symptoms and high-risk sex. An interaction effect between polysubstance use (defined by using 3 or more substances in the past six months) and depressive symptoms (defined by HADS scores) revealed that the combination of these factors was associated with increased risk for high-risk sex - supporting a syndemic understanding of the production of HIV risk. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Pseudorandom dynamics of frequency combs in free-running quantum cascade lasers

    Science.gov (United States)

    Henry, Nathan; Burghoff, David; Yang, Yang; Hu, Qing; Khurgin, Jacob B.

    2018-01-01

    Recent research has shown that free-running quantum cascade lasers are capable of producing frequency combs in midinfrared and THz regions of the spectrum. Unlike familiar frequency combs originating from mode-locked lasers, these do not require any additional optical elements inside the cavity and have temporal characteristics that are dramatically different from the periodic pulse train of conventional combs. Frequency combs from quantum cascade lasers are characterized by the absence of sharp pulses and strong frequency modulation, periodic with the cavity round trip time but lacking any periodicity within that period. To explicate for this seemingly perplexing behavior, we develop a model of the gain medium using optical Bloch equations that account for hole burning in spectral, spatial, and temporal domains. With this model, we confirm that the most efficient mode of operation of a free-running quantum cascade laser is indeed a pseudorandom frequency-modulated field with nearly constant intensity. We show that the optimum modulation period is commensurate with the gain recovery time of the laser medium and the optimum modulation amplitude is comparable to the gain bandwidth, behavior that has been observed in the experiments.

  4. Adaptive sampling dual terahertz comb spectroscopy using dual free-running femtosecond lasers.

    Science.gov (United States)

    Yasui, Takeshi; Ichikawa, Ryuji; Hsieh, Yi-Da; Hayashi, Kenta; Cahyadi, Harsono; Hindle, Francis; Sakaguchi, Yoshiyuki; Iwata, Tetsuo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Minoshima, Kaoru; Inaba, Hajime

    2015-06-02

    Terahertz (THz) dual comb spectroscopy (DCS) is a promising method for high-accuracy, high-resolution, broadband THz spectroscopy because the mode-resolved THz comb spectrum includes both broadband THz radiation and narrow-line CW-THz radiation characteristics. In addition, all frequency modes of a THz comb can be phase-locked to a microwave frequency standard, providing excellent traceability. However, the need for stabilization of dual femtosecond lasers has often hindered its wide use. To overcome this limitation, here we have demonstrated adaptive-sampling THz-DCS, allowing the use of free-running femtosecond lasers. To correct the fluctuation of the time and frequency scales caused by the laser timing jitter, an adaptive sampling clock is generated by dual THz-comb-referenced spectrum analysers and is used for a timing clock signal in a data acquisition board. The results not only indicated the successful implementation of THz-DCS with free-running lasers but also showed that this configuration outperforms standard THz-DCS with stabilized lasers due to the slight jitter remained in the stabilized lasers.

  5. Designing maleic anhydride-{alpha}-olifin copolymeric combs as wax crystal growth nucleators

    Energy Technology Data Exchange (ETDEWEB)

    Soni, Hemant P. [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390 002 (India); Kiranbala; Bharambe, D.P. [Department of Applied Chemistry, Faculty of Technology and Engineering, The Maharaja Sayajirao University of Baroda, Vadodara-390 001 (India); Agrawal, K.S. [Department of Petrochemical Technology, Polytechnic, The Maharaja Sayajirao University of Baroda, Vadodara-390 002 (India); Nagar, A. [MH ASSET, ONGC, Mumbai (India)

    2010-09-15

    Modification of the wax crystal habit is of great practical interest during transportation and processing of crude oil at low temperature. Various pour point depressant (PPD) additives can facilitate this modification by different mechanisms. Comb shaped polymer additives are known to depress the pour point of crude oil by providing different nucleation sites for the precipitation of wax. This paper describes performance based design, synthesis, characterization and evaluation of comb shaped polymeric diesters. Copolymers of maleic anhydride with different unsaturated C{sub 22} esters were synthesized and copolymers then reacted with two unsaturated fatty alcohols. All products were characterized by Fourier Transform Infra Red (FTIR) spectroscopy and Gel Permeation Chromatography (GPC). Rheological properties of crude (with and without additive) were studied by Advance Rheometer AR-500. In this study the additive based on oleic acid was evaluated as good PPD and rheology modifier. (author)

  6. Superdiffusion of cancer on a comb structure

    International Nuclear Information System (INIS)

    Iomin, Alexander

    2005-01-01

    The influence of cell fission on transport properties of the vessel network is studied. A simple mathematical model is proposed by virtue of heuristic arguments on tumor development. The constructed model is a modification of a so-called comb structure. In the framework of this model we are able to show that the tumor development corresponds to fractional transport of cells. A possible answer to the question how the malignant neoplasm cells appear at an arbitrary distance from the primary tumor is proposed. The model could also be a possible mechanism for diffusive cancers

  7. Wax combs mediate nestmate recognition by guard honeybees

    DEFF Research Database (Denmark)

    D'Ettorre, Patrizia; Wenseleers, Tom; Dawson, Jenny

    2006-01-01

    Research has shown that the wax combs are important in the acquisition of colony odour in the honeybee, Apis mellifera. However, many of these studies were conducted in the laboratory or under artificial conditions. We investigated the role of the wax combs in nestmate recognition in the natural...

  8. Generation of green frequency comb from chirped χ{sup (2)} nonlinear photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lai, C.-M. [Department of Electronic Engineering, Ming Chuan University, Taoyuan, Taiwan (China); Chang, K.-H.; Yang, Z.-Y.; Fu, S.-H.; Tsai, S.-T.; Hsu, C.-W.; Peng, L.-H. [Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan (China); Yu, N. E. [Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Boudrioua, A. [LPL, CNRS - UMR 7538, Université Paris 13, Sorbone Paris Cité (France); Kung, A. H. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan (China); Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan (China)

    2014-12-01

    Spectrally broad frequency comb generation over 510–555 nm range was reported on chirped quasi-phase-matching (QPM) χ{sup (2)} nonlinear photonic crystals of 12 mm length with periodicity stepwise increased from 5.9 μm to 7.1 μm. When pumped with nanosecond infrared (IR) frequency comb derived from a QPM optical parametric oscillator (OPO) and spanned over 1040 nm to 1090 nm wavelength range, the 520 nm to 545 nm up-converted green spectra were shown to consist of contributions from (a) second-harmonic generation among the signal or the idler modes, and (b) sum-frequency generation (SFG) from the neighboring pairs of the signal or the idler modes. These mechanisms led the up-converted green frequency comb to have the same mode spacing of 450 GHz as that in the IR-OPO pump comb. As the pump was further detuned from the aforementioned near-degeneracy point and moved toward the signal (1020–1040 nm) and the idler (1090–1110 nm) spectral range, the above QPM parametric processes were preserved in the chirped QPM devices to support up-converted green generation in the 510–520 nm and the 545–555 nm spectral regime. Additional 530–535 nm green spectral generation was also observed due to concurrence of multi-wavelength SFG processes between the (signal, idler) mode pairs. These mechanisms facilitate the chirped QPM device to support a single-pass up-conversion efficiency ∼10% when subject to an IR-OPO pump comb with 200 mW average power operated near- or off- the degeneracy point.

  9. Circumvention of noise contributions in fiber laser based frequency combs.

    Science.gov (United States)

    Benkler, Erik; Telle, Harald; Zach, Armin; Tauser, Florian

    2005-07-25

    We investigate the performance of an Er:fiber laser based femtosecond frequency comb for precision metrological applications. Instead of an active stabilization of the comb, the fluctuations of the carrier-envelope offset phase, the repetition phase, and the phase of the beat from a comb line with an optical reference are synchronously detected. We show that these fluctuations can be effectively eliminated by exploiting their known correlation. In our experimental scheme, we utilize two identically constructed frequency combs for the measurement of the fluctuations, rejecting the influence of a shared optical reference. From measuring a white frequency noise level, we demonstrate that a fractional frequency instability better than 1.4 x 10(-14) for 1 s averaging time can be achieved in frequency metrology applications using the Er:fiber based frequency comb.

  10. Coherent radio-frequency detection for narrowband direct comb spectroscopy.

    Science.gov (United States)

    Anstie, James D; Perrella, Christopher; Light, Philip S; Luiten, Andre N

    2016-02-22

    We demonstrate a scheme for coherent narrowband direct optical frequency comb spectroscopy. An extended cavity diode laser is injection locked to a single mode of an optical frequency comb, frequency shifted, and used as a local oscillator to optically down-mix the interrogating comb on a fast photodetector. The high spectral coherence of the injection lock generates a microwave frequency comb at the output of the photodiode with very narrow features, enabling spectral information to be further down-mixed to RF frequencies, allowing optical transmittance and phase to be obtained using electronics commonly found in the lab. We demonstrate two methods for achieving this step: a serial mode-by-mode approach and a parallel dual-comb approach, with the Cs D1 transition at 894 nm as a test case.

  11. Optically stabilized Erbium fiber frequency comb with hybrid mode-locking and a broad tunable range of repetition rate.

    Science.gov (United States)

    Yang, Honglei; Wu, Xuejian; Zhang, Hongyuan; Zhao, Shijie; Yang, Lijun; Wei, Haoyun; Li, Yan

    2016-12-01

    We present an optically stabilized Erbium fiber frequency comb with a broad repetition rate tuning range based on a hybrid mode-locked oscillator. We lock two comb modes to narrow-linewidth reference lasers in turn to investigate the best performance of control loops. The control bandwidth of fast and slow piezoelectric transducers reaches 70 kHz, while that of pump current modulation with phase-lead compensation is extended to 32 kHz, exceeding laser intrinsic response. Eventually, simultaneous lock of both loops is realized to totally phase-stabilize the comb, which will facilitate precision dual-comb spectroscopy, laser ranging, and timing distribution. In addition, a 1.8-MHz span of the repetition rate is achieved by an automatic optical delay line that is helpful in manufacturing a secondary comb with a similar repetition rate. The oscillator is housed in a homemade temperature-controlled box with an accuracy of ±0.02  K, which not only keeps high signal-to-noise ratio of the beat notes with reference lasers, but also guarantees self-starting at the same mode-locking every time.

  12. Unidirectional, dual-comb lasing under multiple pulse formation mechanisms in a passively mode-locked fiber ring laser

    Science.gov (United States)

    Liu, Ya; Zhao, Xin; Hu, Guoqing; Li, Cui; Zhao, Bofeng; Zheng, Zheng

    2016-09-01

    Dual-comb lasers from which asynchronous ultrashort pulses can be simultaneously generated have recently become an interesting research subject. They could be an intriguing alternative to the current dual-laser optical-frequency-comb source with highly sophisticated electronic control systems. If generated through a common light path traveled by all pulses, the common-mode noises between the spectral lines of different pulse trains could be significantly reduced. Therefore, coherent dual-comb generation from a completely common-path, unidirectional lasing cavity would be an interesting territory to explore. In this paper, we demonstrate such a dual-comb lasing scheme based on a nanomaterial saturable absorber with additional pulse narrowing and broadening mechanisms concurrently introduced into a mode-locked fiber laser. The interactions between multiple soliton formation mechanisms result in unusual bifurcation into two-pulse states with quite different characteristics. Simultaneous oscillation of pulses with four-fold difference in pulsewidths and tens of Hz repetition rate difference is observed. The coherence between these spectral-overlapped, picosecond and femtosecond pulses is further verified by the corresponding asynchronous cross-sampling and dual-comb spectroscopy measurements.

  13. Mid-Infrared Frequency-Agile Dual-Comb Spectroscopy

    Science.gov (United States)

    Luo, Pei-Ling; Yan, Ming; Iwakuni, Kana; Millot, Guy; Hänsch, Theodor W.; Picqué, Nathalie

    2016-06-01

    We demonstrate a new approach to mid-infrared dual-comb spectroscopy. It opens up new opportunities for accurate real-time spectroscopic diagnostics and it significantly simplifies the technique of dual-comb spectroscopy. Two mid-infrared frequency combs of slightly different repetition frequencies and moderate, but rapidly tunable, spectral span are generated in the 2800-3200 cm-1 region. The generators rely on electro-optic modulators, nonlinear fibers for spectral broadening and difference frequency generation and do not involve mode-locked lasers. Flat-top frequency combs span up to 10 cm-1 with a comb line spacing of 100 MHz (3×10-3 cm-1). The performance of the spectrometer without any phase-lock electronics or correction scheme is illustrated with spectra showing resolved comb lines and Doppler-limited spectra of methane. High precision on the spectroscopic parameter (line positions and intensities) determination is demonstrated for spectra measured on a millisecond time scale and it is validated with comparison with literature data. G. Millot, S. Pitois, M. Yan, T. Hovannysyan, A. Bendahmane, T.W. Hänsch, N. Picqué, Frequency-agile dual-comb spectroscopy, Nature Photonics 10, 27-30 (2016).

  14. Linear and Nonlinear Molecular Spectroscopy with Laser Frequency Combs

    Science.gov (United States)

    Picque, Nathalie

    2013-06-01

    The regular pulse train of a mode-locked femtosecond laser can give rise to a comb spectrum of millions of laser modes with a spacing precisely equal to the pulse repetition frequency. Laser frequency combs were conceived a decade ago as tools for the precision spectroscopy of atomic hydrogen. They are now becoming enabling tools for an increasing number of applications, including molecular spectroscopy. Recent experiments of multi-heterodyne frequency comb Fourier transform spectroscopy (also called dual-comb spectroscopy) have demonstrated that the precisely spaced spectral lines of a laser frequency comb can be harnessed for new techniques of linear absorption spectroscopy. The first proof-of-principle experiments have demonstrated a very exciting potential of dual-comb spectroscopy without moving parts for ultra-rapid and ultra-sensitive recording of complex broad spectral bandwidth molecular spectra. Compared to conventional Michelson-based Fourier transform spectroscopy, recording times could be shortened from seconds to microseconds, with intriguing prospects for spectroscopy of short lived transient species. The resolution improves proportionally to the measurement time. Therefore longer recordings allow high resolution spectroscopy of molecules with extreme precision, since the absolute frequency of each laser comb line can be known with the accuracy of an atomic clock. Moreover, since laser frequency combs involve intense ultrashort laser pulses, nonlinear interactions can be harnessed. Broad spectral bandwidth ultra-rapid nonlinear molecular spectroscopy and imaging with two laser frequency combs is demonstrated with coherent Raman effects and two-photon excitation. Real-time multiplex accessing of hyperspectral images may dramatically expand the range of applications of nonlinear microscopy. B. Bernhardt et al., Nature Photonics 4, 55-57 (2010); A. Schliesser et al. Nature Photonics 6, 440-449 (2012); T. Ideguchi et al. arXiv:1201.4177 (2012) T

  15. Comb to Pipeline: Fast Software Encryption Revisited

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Lauridsen, Martin Mehl; Tischhauser, Elmar Wolfgang

    2015-01-01

    AES-NI, or Advanced Encryption Standard New Instructions, is an extension of the x86 architecture proposed by Intel in 2008. With a pipelined implementation utilizing AES-NI, parallelizable modes such as AES-CTR become extremely efficient. However, out of the four non-trivial NIST......-recommended encryption modes, three are inherently sequential: CBC, CFB, and OFB. This inhibits the advantage of using AES-NI significantly. Similar observations apply to CMAC, CCM and a great deal of other modes. We address this issue by proposing the comb scheduler – a fast scheduling algorithm based on an efficient....... We observe a drastic speed-up of factor 5 for NIST’s CBC, CFB, OFB and CMAC performing around 0.88 cpb. Surprisingly, contrary to the entire body of previous performance analysis, the throughput of the authenticated encryption (AE) mode CCM gets very close to that of GCM and OCB3, with about 1.64 cpb...

  16. Optical frequency comb Faraday rotation spectroscopy

    Science.gov (United States)

    Johansson, Alexandra C.; Westberg, Jonas; Wysocki, Gerard; Foltynowicz, Aleksandra

    2018-05-01

    We demonstrate optical frequency comb Faraday rotation spectroscopy (OFC-FRS) for broadband interference-free detection of paramagnetic species. The system is based on a femtosecond doubly resonant optical parametric oscillator and a fast-scanning Fourier transform spectrometer (FTS). The sample is placed in a DC magnetic field parallel to the light propagation. Efficient background suppression is implemented via switching the direction of the field on consecutive FTS scans and subtracting the consecutive spectra, which enables long-term averaging. In this first demonstration, we measure the entire Q- and R-branches of the fundamental band of nitric oxide in the 5.2-5.4 µm range and achieve good agreement with a theoretical model.

  17. Thermally controlled comb generation and soliton modelocking in microresonators.

    Science.gov (United States)

    Joshi, Chaitanya; Jang, Jae K; Luke, Kevin; Ji, Xingchen; Miller, Steven A; Klenner, Alexander; Okawachi, Yoshitomo; Lipson, Michal; Gaeta, Alexander L

    2016-06-01

    We report, to the best of our knowledge, the first demonstration of thermally controlled soliton mode-locked frequency comb generation in microresonators. By controlling the electric current through heaters integrated with silicon nitride microresonators, we demonstrate a systematic and repeatable pathway to single- and multi-soliton mode-locked states without adjusting the pump laser wavelength. Such an approach could greatly simplify the generation of mode-locked frequency combs and facilitate applications such as chip-based dual-comb spectroscopy.

  18. Picometer-resolution dual-comb spectroscopy with a free-running fibre laser

    OpenAIRE

    Zhao, Xin; Hu, Guoqing; Zhao, Bofeng; Li, Cui; Pan, Yingling; Liu, Ya; Yasui, Takeshi; Zheng, Zheng

    2016-01-01

    Dual-comb spectroscopy utilizes two sets of comb lines with slightly different comb-tooth-spacings, and optical spectral information is acquired by measuring the radio-frequency beat notes between the sets of comb lines. It holds the promise as a real-time, high-resolution analytical spectroscopy tool for a range of applications. However, the stringent requirement on the coherence between comb lines from two separate lasers and the sophisticated control system to achieve that have confined th...

  19. Long distance measurement with a femtosecond laser based frequency comb

    Science.gov (United States)

    Bhattacharya, N.; Cui, M.; Zeitouny, M. G.; Urbach, H. P.; van den Berg, S. A.

    2017-11-01

    Recent advances in the field of ultra-short pulse lasers have led to the development of reliable sources of carrier envelope phase stabilized femtosecond pulses. The pulse train generated by such a source has a frequency spectrum that consists of discrete, regularly spaced lines known as a frequency comb. In this case both the frequency repetition and the carrier-envelope-offset frequency are referenced to a frequency standard, like an atomic clock. As a result the accuracy of the frequency standard is transferred to the optical domain, with the frequency comb as transfer oscillator. These unique properties allow the frequency comb to be applied as a versatile tool, not only for time and frequency metrology, but also in fundamental physics, high-precision spectroscopy, and laser noise characterization. The pulse-to-pulse phase relationship of the light emitted by the frequency comb has opened up new directions for long range highly accurate distance measurement.

  20. High density terahertz frequency comb produced by coherent synchrotron radiation

    Science.gov (United States)

    Tammaro, S.; Pirali, O.; Roy, P.; Lampin, J.-F.; Ducournau, G.; Cuisset, A.; Hindle, F.; Mouret, G.

    2015-07-01

    Frequency combs have enabled significant progress in frequency metrology and high-resolution spectroscopy extending the achievable resolution while increasing the signal-to-noise ratio. In its coherent mode, synchrotron radiation is accepted to provide an intense terahertz continuum covering a wide spectral range from about 0.1 to 1 THz. Using a dedicated heterodyne receiver, we reveal the purely discrete nature of this emission. A phase relationship between the light pulses leads to a powerful frequency comb spanning over one decade in frequency. The comb has a mode spacing of 846 kHz, a linewidth of about 200 Hz, a fractional precision of about 2 × 10-10 and no frequency offset. The unprecedented potential of the comb for high-resolution spectroscopy is demonstrated by the accurate determination of pure rotation transitions of acetonitrile.

  1. Ultrafast optical ranging using microresonator soliton frequency combs

    Science.gov (United States)

    Trocha, P.; Karpov, M.; Ganin, D.; Pfeiffer, M. H. P.; Kordts, A.; Wolf, S.; Krockenberger, J.; Marin-Palomo, P.; Weimann, C.; Randel, S.; Freude, W.; Kippenberg, T. J.; Koos, C.

    2018-02-01

    Light detection and ranging is widely used in science and industry. Over the past decade, optical frequency combs were shown to offer advantages in optical ranging, enabling fast distance acquisition with high accuracy. Driven by emerging high-volume applications such as industrial sensing, drone navigation, or autonomous driving, there is now a growing demand for compact ranging systems. Here, we show that soliton Kerr comb generation in integrated silicon nitride microresonators provides a route to high-performance chip-scale ranging systems. We demonstrate dual-comb distance measurements with Allan deviations down to 12 nanometers at averaging times of 13 microseconds along with ultrafast ranging at acquisition rates of 100 megahertz, allowing for in-flight sampling of gun projectiles moving at 150 meters per second. Combining integrated soliton-comb ranging systems with chip-scale nanophotonic phased arrays could enable compact ultrafast ranging systems for emerging mass applications.

  2. Coherent cavity-enhanced dual-comb spectroscopy

    OpenAIRE

    Fleisher, Adam J.; Long, David A.; Reed, Zachary D.; Hodges, Joseph T.; Plusquellic, David F.

    2016-01-01

    Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of high-resolution spectra without the need for moving parts or low-resolution dispersive optics. This method of broadband spectroscopy is most often accomplished via tight phase locking of two mode-locked lasers or via sophisticated signal processing algorithms, and therefore, long integration times of phase coherent signals are difficult to achieve. Here we demonstrate an alternative approach to dual-comb spectroscopy usin...

  3. Adaptive real-time dual-comb spectroscopy

    OpenAIRE

    Ideguchi, Takuro; Poisson, Antonin; Guelachvili, Guy; Picque, Nathalie; Hansch, Theodor W.

    2014-01-01

    The spectrum of a laser frequency comb consists of several hundred thousand equally spaced lines over a broad spectral bandwidth. Such frequency combs have revolutionized optical frequency metrology and they now hold much promise for significant advances in a growing number of applications including molecular spectroscopy. Despite an intriguing potential for the measurement of molecular spectra spanning tens of nanometres within tens of microseconds at Doppler-limited resolution, the developm...

  4. Microresonator-Based Optical Frequency Combs: A Time Domain Perspective

    Science.gov (United States)

    2016-04-19

    AFRL-AFOSR-VA-TR-2016-0165 (BRI) Microresonator-Based Optical Frequency Combs: A Time Domain Perspective Andrew Weiner PURDUE UNIVERSITY 401 SOUTH...Optical Frequency Combs: A Time Domain Perspective 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-12-1-0236 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data

  5. Radiative properties tailoring of grating by comb-drive microactuator

    International Nuclear Information System (INIS)

    Jiao, Y.; Liu, L.H.; Liu, L.J.; Hsu, P.-F.

    2014-01-01

    Micro-scale grating structures are widely researched in recent years. Although micro-scale fabrication technology is highly advanced today, with grating aspect ratio greater than 25:1 being achievable some fabrication requirements, such as fine groove processing, are still challenging. Comb-drive microactuator is proposed in this paper to be utilized on simple binary grating structures for tailoring or modulating spectral radiation properties by active adjustment. The rigorous coupled-wave analysis (RCWA) is used to calculate the absorptance of proposed structures and to investigate the impacts brought by the geometry and displacement of comb-drive microactuator. The results show that the utilization of comb-drive microactuator on grating improves the absorptance of simple binary grating while avoiding the difficulty fine groove processing. Spectral radiation property tailoring after gratings are fabricated becomes possible with the comb-drive microactuator structure. - Highlights: • A microscale grating structure with comb-driven microactuator is proposed. • The movement of microactuator changes peak absorptance resonance wavelength. • Geometric and displacement effects of comb finger on absorptance are investigated. • Both RCWA and LC circuit models are developed to predict the resonance wavelength. • Resonance frequency equations of LC circuits allow quick design analysis

  6. Adaptive real-time dual-comb spectroscopy

    Science.gov (United States)

    Ideguchi, Takuro; Poisson, Antonin; Guelachvili, Guy; Picqué, Nathalie; Hänsch, Theodor W.

    2014-01-01

    The spectrum of a laser frequency comb consists of several hundred thousand equally spaced lines over a broad spectral bandwidth. Such frequency combs have revolutionized optical frequency metrology and they now hold much promise for significant advances in a growing number of applications including molecular spectroscopy. Despite an intriguing potential for the measurement of molecular spectra spanning tens of nanometres within tens of microseconds at Doppler-limited resolution, the development of dual-comb spectroscopy is hindered by the demanding stability requirements of the laser combs. Here we overcome this difficulty and experimentally demonstrate a concept of real-time dual-comb spectroscopy, which compensates for laser instabilities by electronic signal processing. It only uses free-running mode-locked lasers without any phase-lock electronics. We record spectra spanning the full bandwidth of near-infrared fibre lasers with Doppler-limited line profiles highly suitable for measurements of concentrations or line intensities. Our new technique of adaptive dual-comb spectroscopy offers a powerful transdisciplinary instrument for analytical sciences. PMID:24572636

  7. Coherent cavity-enhanced dual-comb spectroscopy.

    Science.gov (United States)

    Fleisher, Adam J; Long, David A; Reed, Zachary D; Hodges, Joseph T; Plusquellic, David F

    2016-05-16

    Dual-comb spectroscopy allows for the rapid, multiplexed acquisition of high-resolution spectra without the need for moving parts or low-resolution dispersive optics. This method of broadband spectroscopy is most often accomplished via tight phase locking of two mode-locked lasers or via sophisticated signal processing algorithms, and therefore, long integration times of phase coherent signals are difficult to achieve. Here we demonstrate an alternative approach to dual-comb spectroscopy using two phase modulator combs originating from a single continuous-wave laser capable of > 2 hours of coherent real-time averaging. The dual combs were generated by driving the phase modulators with step-recovery diodes where each comb consisted of > 250 teeth with 203 MHz spacing and spanned > 50 GHz region in the near-infrared. The step-recovery diodes are passive devices that provide low-phase-noise harmonics for efficient coupling into an enhancement cavity at picowatt optical powers. With this approach, we demonstrate the sensitivity to simultaneously monitor ambient levels of CO2, CO, HDO, and H2O in a single spectral region at a maximum acquisition rate of 150 kHz. Robust, compact, low-cost and widely tunable dual-comb systems could enable a network of distributed multiplexed optical sensors.

  8. Adaptive real-time dual-comb spectroscopy

    Science.gov (United States)

    Ideguchi, Takuro; Poisson, Antonin; Guelachvili, Guy; Picqué, Nathalie; Hänsch, Theodor W.

    2014-02-01

    The spectrum of a laser frequency comb consists of several hundred thousand equally spaced lines over a broad spectral bandwidth. Such frequency combs have revolutionized optical frequency metrology and they now hold much promise for significant advances in a growing number of applications including molecular spectroscopy. Despite an intriguing potential for the measurement of molecular spectra spanning tens of nanometres within tens of microseconds at Doppler-limited resolution, the development of dual-comb spectroscopy is hindered by the demanding stability requirements of the laser combs. Here we overcome this difficulty and experimentally demonstrate a concept of real-time dual-comb spectroscopy, which compensates for laser instabilities by electronic signal processing. It only uses free-running mode-locked lasers without any phase-lock electronics. We record spectra spanning the full bandwidth of near-infrared fibre lasers with Doppler-limited line profiles highly suitable for measurements of concentrations or line intensities. Our new technique of adaptive dual-comb spectroscopy offers a powerful transdisciplinary instrument for analytical sciences.

  9. On-chip dual-comb source for spectroscopy.

    Science.gov (United States)

    Dutt, Avik; Joshi, Chaitanya; Ji, Xingchen; Cardenas, Jaime; Okawachi, Yoshitomo; Luke, Kevin; Gaeta, Alexander L; Lipson, Michal

    2018-03-01

    Dual-comb spectroscopy is a powerful technique for real-time, broadband optical sampling of molecular spectra, which requires no moving components. Recent developments with microresonator-based platforms have enabled frequency combs at the chip scale. However, the need to precisely match the resonance wavelengths of distinct high quality-factor microcavities has hindered the development of on-chip dual combs. We report the simultaneous generation of two microresonator combs on the same chip from a single laser, drastically reducing experimental complexity. We demonstrate broadband optical spectra spanning 51 THz and low-noise operation of both combs by deterministically tuning into soliton mode-locked states using integrated microheaters, resulting in narrow (lasers or microwave oscillators. We demonstrate high signal-to-noise ratio absorption spectroscopy spanning 170 nm using the dual-comb source over a 20-μs acquisition time. Our device paves the way for compact and robust spectrometers at nanosecond time scales enabled by large beat-note spacings (>1 GHz).

  10. Fast Interrogation of Fiber Bragg Gratings with Electro-Optical Dual Optical Frequency Combs.

    Science.gov (United States)

    Posada-Roman, Julio E; Garcia-Souto, Jose A; Poiana, Dragos A; Acedo, Pablo

    2016-11-26

    Optical frequency combs (OFC) generated by electro-optic modulation of continuous-wave lasers provide broadband coherent sources with high power per line and independent control of line spacing and the number of lines. In addition to their application in spectroscopy, they offer flexible and optimized sources for the interrogation of other sensors based on wavelength change or wavelength filtering, such as fiber Bragg grating (FBG) sensors. In this paper, a dual-OFC FBG interrogation system based on a single laser and two optical-phase modulators is presented. This architecture allows for the configuration of multimode optical source parameters such as the number of modes and their position within the reflected spectrum of the FBG. A direct read-out is obtained by mapping the optical spectrum onto the radio-frequency spectrum output of the dual-comb. This interrogation scheme is proposed for measuring fast phenomena such as vibrations and ultrasounds. Results are presented for dual-comb operation under optimized control. The optical modes are mapped onto detectable tones that are multiples of 0.5 MHz around a center radiofrequency tone (40 MHz). Measurements of ultrasounds (40 kHz and 120 kHz) are demonstrated with this sensing system. Ultrasounds induce dynamic strain onto the fiber, which generates changes in the reflected Bragg wavelength and, hence, modulates the amplitude of the OFC modes within the reflected spectrum. The amplitude modulation of two counterphase tones is detected to obtain a differential measurement proportional to the ultrasound signal.

  11. A mummified duck-billed dinosaur with a soft-tissue cock's comb.

    Science.gov (United States)

    Bell, Phil R; Fanti, Federico; Currie, Philip J; Arbour, Victoria M

    2014-01-06

    Among living vertebrates, soft tissues are responsible for labile appendages (combs, wattles, proboscides) that are critical for activities ranging from locomotion to sexual display [1]. However, soft tissues rarely fossilize, and such soft-tissue appendages are unknown for many extinct taxa, including dinosaurs. Here we report a remarkable "mummified" specimen of the hadrosaurid dinosaur Edmontosaurus regalis from the latest Cretaceous Wapiti Formation, Alberta, Canada, that preserves a three-dimensional cranial crest (or "comb") composed entirely of soft tissue. Previously, crest function has centered on the hypertrophied nasal passages of lambeosaurine hadrosaurids, which acted as resonance chambers during vocalization [2-4]. The fleshy comb in Edmontosaurus necessitates an alternative explanation most likely related to either social signaling or sexual selection [5-7]. This discovery provides the first view of bizarre, soft-tissue signaling structures in a dinosaur and provides additional evidence for social behavior. Crest evolution within Hadrosaurinae apparently culminated in the secondary loss of the bony crest at the terminal Cretaceous; however, the new specimen indicates that cranial ornamentation was in fact not lost but substituted in Edmontosaurus by a fleshy display structure. It also implies that visual display played a key role in the evolution of hadrosaurine crests and raises the possibility of similar soft-tissue structures among other dinosaurs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Quantum Theory of Conditional Phonon States in a Dual-Pumped Raman Optical Frequency Comb

    Science.gov (United States)

    Mondloch, Erin

    In this work, we theoretically and numerically investigate nonclassical phonon states created in the collective vibration of a Raman medium by the generation of a dual-pumped Raman optical frequency comb in an optical cavity. This frequency comb is generated by cascaded Raman scattering driven by two phase-locked pump lasers that are separated in frequency by three times the Raman phonon frequency. We characterize the variety of conditioned phonon states that are created when the number of photons in all optical frequency modes except the pump modes are measured. Almost all of these conditioned phonon states are extremely well approximated as three-phonon-squeezed states or Schrodinger-cat states, depending on the outcomes of the photon number measurements. We show how the combinations of first-, second-, and third-order Raman scattering that correspond to each set of measured photon numbers determine the fidelity of the conditioned phonon state with model three-phonon-squeezed states and Schrodinger-cat states. All of the conditioned phonon states demonstrate preferential growth of the phonon mode along three directions in phase space. That is, there are three preferred phase values that the phonon state takes on as a result of Raman scattering. We show that the combination of Raman processes that produces a given set of measured photon numbers always produces phonons in multiples of three. In the quantum number-state representation, these multiples of three are responsible for the threefold phase-space symmetry seen in the conditioned phonon states. With a semiclassical model, we show how this three-phase preference can also be understood in light of phase correlations that are known to spontaneously arise in single-pumped Raman frequency combs. Additionally, our semiclassical model predicts that the optical modes also grow preferentially along three phases, suggesting that the dual-pumped Raman optical frequency comb is partially phase-stabilized.

  13. Phylogenetic analyses of the genus Glaciecola: emended description of the genus Glaciecola, transfer of Glaciecola mesophila, G. agarilytica, G. aquimarina, G. arctica, G. chathamensis, G. polaris and G. psychrophila to the genus Paraglaciecola gen. nov. as Paraglaciecola mesophila comb. nov., P. agarilytica comb. nov., P. aquimarina comb. nov., P. arctica comb. nov., P. chathamensis comb. nov., P. polaris comb. nov. and P. psychrophila comb. nov., and description of Paraglaciecola oceanifecundans sp. nov., isolated from the Southern Ocean.

    Science.gov (United States)

    Shivaji, Sisinthy; Reddy, Gundlapally Sathyanarayana

    2014-09-01

    Phylogenetic analyses of the genus Glaciecola were performed using the sequences of the 16S rRNA gene and the GyrB protein to establish its taxonomic status. The results indicated a consistent clustering of the genus Glaciecola into two clades, with significant bootstrap values, with all the phylogenetic methods employed. Clade 1 was represented by seven species, Glaciecola agarilytica, G. aquimarina, G. arctica, G. chathamensis, G. mesophila, G. polaris and G. psychrophila, while clade 2 consisted of only three species, Glaciecola nitratireducens, G. pallidula and G. punicea. Evolutionary distances between species of clades 1 and 2, based on 16S rRNA gene and GyrB protein sequences, ranged from 93.0 to 95.0 % and 69.0 to 73.0 %, respectively. In addition, clades 1 and 2 possessed 18 unique signature nucleotides, at positions 132, 184 : 193, 185 : 192, 230, 616 : 624, 631, 632, 633, 738, 829, 1257, 1265, 1281, 1356 and 1366, in the 16S rRNA gene sequence and can be differentiated by the occurrence of a 15 nt signature motif 5'-CAAATCAGAATGTTG at positions 1354-1368 in members of clade 2. Robust clustering of the genus Glaciecola into two clades based on analysis of 16S rRNA gene and GyrB protein sequences, 16S rRNA gene sequence similarity of ≤95.0 % and the occurrence of signature nucleotides and signature motifs in the 16S rRNA gene suggested that the genus should be split into two genera. The genus Paraglaciecola gen. nov. is therefore created to accommodate the seven species of clade 1, while the name Glaciecola sensu stricto is retained to represent species of clade 2. The species of clade 1 are transferred to the genus Paraglaciecola as Paraglaciecola mesophila comb. nov. (type strain DSM 15026(T) = KMM 241(T)), P. agarilytica comb. nov. (type strain NO2(T) = KCTC 12755(T) = LMG 23762(T)), P. aquimarina comb. nov. (type strain GGW-M5(T) = KCTC 32108(T) = CCUG 62918(T)), P. arctica comb. nov. (type strain BSs20135(T

  14. Micro-combs: A novel generation of optical sources

    Science.gov (United States)

    Pasquazi, Alessia; Peccianti, Marco; Razzari, Luca; Moss, David J.; Coen, Stéphane; Erkintalo, Miro; Chembo, Yanne K.; Hansson, Tobias; Wabnitz, Stefan; Del'Haye, Pascal; Xue, Xiaoxiao; Weiner, Andrew M.; Morandotti, Roberto

    2018-01-01

    -integrated technologies. Indeed, it is well acknowledged by the electronics industry that future generations of computer processing chips will inevitably require an extremely high density of copper-based interconnections, significantly increasing the chip power dissipation to beyond practical levels [15-17]; hence, conventional approaches to chip design must undergo radical changes. On-chip optical networks, or optical interconnects, can offer high speed and low energy per-transferred-bit, and micro-resonators are widely seen as a key component to interface the electronic world with photonics. Many information technology industries have recently focused on the development of integrated ring resonators to be employed for electrically-controlled light modulators [14-17], greatly advancing the maturity of micro-resonator technology as a whole. Recently [11-13], the demonstration of OFC sources in micro-resonators fabricated in electronic (i.e. in complementary metal oxide semiconductor (CMOS)) compatible platforms has given micro-cavities an additional appeal, with the possibility of exploiting them as light sources in microchips. This scenario is creating fierce competition in developing highly efficient OFC generators based on micro-cavities which can radically change the nature of information transport and processing. Even in telecommunications, perhaps a more conventional environment for optical technologies, novel time-division multiplexed optical systems will require extremely stable optical clocks at ultra-high pulse repetition-rates towards the THz scale. Furthermore, arbitrary pulse generators based on OFC [18,19] are seen as one of the most promising solutions for this next generation of high-capacity optical coherent communication systems. This review will summarise the recent exciting achievements in the field of micro-combs, namely optical frequency combs based on high-Q micro-resonators, with a perspective on both the potential of this technology, as well as the open questions

  15. Ultraflat and broadband optical frequency comb generator based on cascaded two dual-electrode Mach-Zehnder modulators

    Science.gov (United States)

    Qu, Kun; Zhao, Shanghong; Li, Xuan; Tan, Qinggui; Zhu, Zihang

    2018-04-01

    A novel scheme for the generation of ultraflat and broadband optical frequency comb (OFC) is proposed based on cascaded two dual-electrode Mach-Zehnder modulators (DE-MZM). The first DE-MZM can generate a four-comb-line OFC, then the OFC is injected into the second DE-MZM as a carrier, which can increase the number of comb lines. Our modified scheme finally can generate a broadband OFC with high flatness by simply modifying the electrical power and the bias voltage of the DE-MZM. Theoretical analysis and simulation results reveal that a 16-comb-line OFC with a frequency spacing that two times the frequency of the RF signal can be obtained. The power fluctuation of the OFC lines is 0.48 dB and the unwanted-mode suppression ratio (UMSR) can reach 16.5 dB. Additionally, whether the bias drift of the DE-MZMs has little influence on the power fluctuation is also analyzed. These results demonstrate the robustness of our scheme and verify its good accuracy and high stability with perfect flatness.

  16. Cognitive Aspects of Comb-Building in the Honeybee?

    Directory of Open Access Journals (Sweden)

    Vincent Gallo

    2018-06-01

    Full Text Available The wax-made comb of the honeybee is a masterpiece of animal architecture. The highly regular, double-sided hexagonal structure is a near-optimal solution to storing food and housing larvae, economizing on building materials and space. Elaborate though they may seem, such animal constructions are often viewed as the result of ‘just instinct,’ governed by inflexible, pre-programmed, innate behavior routines. An inspection of the literature on honeybee comb construction, however, reveals a different picture. Workers have to learn, at least in part, certain elements of the technique, and there is considerable flexibility in terms of how the shape of the comb and its gradual manufacture is tailored to the circumstances, especially the available space. Moreover, we explore the 2-century old and now largely forgotten work by François Huber, where glass screens were placed between an expanding comb construction and the intended target wall. Bees took corrective action before reaching the glass obstacle, and altered the ongoing construction so as to reach the nearest wooden wall. Though further experiments will be necessary, these results suggest a form of spatial planning skills. We discuss these findings in the context of what is now known about insect cognition, and ask if it is possible that the production of hexagonal wax combs is the result of behavioral heuristics where a complex structure emerges as the result of simple behavioral rules applied by each individual, or whether prospective cognition might be involved.

  17. Phrenology, heredity and progress in George Combe's Constitution of Man.

    Science.gov (United States)

    Jenkins, Bill

    2015-09-01

    The Constitution of Man by George Combe (1828) was probably the most influential phrenological work of the nineteenth century. It not only offered an exposition of the phrenological theory of the mind, but also presented Combe's vision of universal human progress through the inheritance of acquired mental attributes. In the decades before the publication of Darwin's Origin of Species, the Constitution was probably the single most important vehicle for the dissemination of naturalistic progressivism in the English-speaking world. Although there is a significant literature on the social and cultural context of phrenology, the role of heredity in Combe's thought has been less thoroughly explored, although both John van Wyhe and Victor L. Hilts have linked Combe's views on heredity with the transformist theories of Jean-Baptiste Lamarck. In this paper I examine the origin, nature and significance of his ideas and argue that Combe's hereditarianism was not directly related to Lamarckian transformism but formed part of a wider discourse on heredity in the early nineteenth century.

  18. Dual-comb spectroscopy of water vapor with a free-running semiconductor disk laser.

    Science.gov (United States)

    Link, S M; Maas, D J H C; Waldburger, D; Keller, U

    2017-06-16

    Dual-comb spectroscopy offers the potential for high accuracy combined with fast data acquisition. Applications are often limited, however, by the complexity of optical comb systems. Here we present dual-comb spectroscopy of water vapor using a substantially simplified single-laser system. Very good spectroscopy measurements with fast sampling rates are achieved with a free-running dual-comb mode-locked semiconductor disk laser. The absolute stability of the optical comb modes is characterized both for free-running operation and with simple microwave stabilization. This approach drastically reduces the complexity for dual-comb spectroscopy. Band-gap engineering to tune the center wavelength from the ultraviolet to the mid-infrared could optimize frequency combs for specific gas targets, further enabling dual-comb spectroscopy for a wider range of industrial applications. Copyright © 2017, American Association for the Advancement of Science.

  19. Robust Frequency Combs and Lasers for Optical Clocks and Sensing, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Vescent Photonics proposes to bring an environmentally robust, compact, high fidelity frequency comb to the commercial market. This will be comb based on a NIST...

  20. Quantum cascade laser combs: effects of modulation and dispersion.

    Science.gov (United States)

    Villares, Gustavo; Faist, Jérôme

    2015-01-26

    Frequency comb formation in quantum cascade lasers is studied theoretically using a Maxwell-Bloch formalism based on a modal decomposition, where dispersion is considered. In the mid-infrared, comb formation persists in the presence of weak cavity dispersion (500 fs2 mm-1) but disappears when much larger values are used (30'000 fs2 mm-1). Active modulation at the round-trip frequency is found to induce mode-locking in THz devices, where the upper state lifetime is in the tens of picoseconds. Our results show that mode-locking based on four-wave mixing in broadband gain, low dispersion cavities is the most promising way of achieving broadband quantum cascade laser frequency combs.

  1. Femtosecond Optical Frequency Comb Technology Principle, Operation and Application

    CERN Document Server

    Ye, Jun

    2005-01-01

    Over the last few years, there has been a remarkable convergence among the fields of ultrafast optics, optical frequency metrology, and precision laser spectroscopy. This convergence has enabled unprecedented advances in control of the electric field of the pulses produced by femtosecond mode-locked lasers. The resulting spectrum consists of a comb of sharp spectral lines with well-defined frequencies. These new techniques and capabilities are generally known as "femtosecond comb technology." They have had dramatic impact on the diverse fields of precision measurement and extreme nonlinear optical physics. This book provides an introductory description of mode-locked lasers, the connection between time and frequency descriptions of their output and the physical origins of the electric field dynamics, together with an overview of applications of femtosecond comb technology. Individual chapters go into more detail on mode-locked laser development, spectral broadening in microstructure fiber, optical parametric ...

  2. Intensity autocorrelation measurements of frequency combs in the terahertz range

    Science.gov (United States)

    Benea-Chelmus, Ileana-Cristina; Rösch, Markus; Scalari, Giacomo; Beck, Mattias; Faist, Jérôme

    2017-09-01

    We report on direct measurements of the emission character of quantum cascade laser based frequency combs, using intensity autocorrelation. Our implementation is based on fast electro-optic sampling, with a detection spectral bandwidth matching the emission bandwidth of the comb laser, around 2.5 THz. We find the output of these frequency combs to be continuous even in the locked regime, but accompanied by a strong intensity modulation. Moreover, with our record temporal resolution of only few hundreds of femtoseconds, we can resolve correlated intensity modulation occurring on time scales as short as the gain recovery time, about 4 ps. By direct comparison with pulsed terahertz light originating from a photoconductive emitter, we demonstrate the peculiar emission pattern of these lasers. The measurement technique is self-referenced and ultrafast, and requires no reconstruction. It will be of significant importance in future measurements of ultrashort pulses from quantum cascade lasers.

  3. Highly coherent free-running dual-comb chip platform.

    Science.gov (United States)

    Hébert, Nicolas Bourbeau; Lancaster, David G; Michaud-Belleau, Vincent; Chen, George Y; Genest, Jérôme

    2018-04-15

    We characterize the frequency noise performance of a free-running dual-comb source based on an erbium-doped glass chip running two adjacent mode-locked waveguide lasers. This compact laser platform, contained only in a 1.2 L volume, rejects common-mode environmental noise by 20 dB thanks to the proximity of the two laser cavities. Furthermore, it displays a remarkably low mutual frequency noise floor around 10  Hz 2 /Hz, which is enabled by its large-mode-area waveguides and low Kerr nonlinearity. As a result, it reaches a free-running mutual coherence time of 1 s since mode-resolved dual-comb spectra are generated even on this time scale. This design greatly simplifies dual-comb interferometers by enabling mode-resolved measurements without any phase lock.

  4. Analytic random-walk model for the coherence of a frequency comb

    Science.gov (United States)

    Eramo, R.; Cancio Pastor, P.; Cavalieri, S.

    2018-03-01

    We present an analytical study of the frequency comb coherence due to random noise in the pulses phases. We derive a simple expression for the comb lineshape, which depends on a single parameter Neff with the physical meaning of number of coherent comb pulses, inversely proportional to the variance of the phase jumps between subsequent comb pulses. A comparison to the case of a cw-monomode laser with white noise frequency fluctuations is also presented.

  5. Modeling methodology for a CMOS-MEMS electrostatic comb

    Science.gov (United States)

    Iyer, Sitaraman V.; Lakdawala, Hasnain; Mukherjee, Tamal; Fedder, Gary K.

    2002-04-01

    A methodology for combined modeling of capacitance and force 9in a multi-layer electrostatic comb is demonstrated in this paper. Conformal mapping-based analytical methods are limited to 2D symmetric cross-sections and cannot account for charge concentration effects at corners. Vertex capacitance can be more than 30% of the total capacitance in a single-layer 2 micrometers thick comb with 10 micrometers overlap. Furthermore, analytical equations are strictly valid only for perfectly symmetrical finger positions. Fringing and corner effects are likely to be more significant in a multi- layered CMOS-MEMS comb because of the presence of more edges and vertices. Vertical curling of CMOS-MEMS comb fingers may also lead to reduced capacitance and vertical forces. Gyroscopes are particularly sensitive to such undesirable forces, which therefore, need to be well-quantified. In order to address the above issues, a hybrid approach of superposing linear regression models over a set of core analytical models is implemented. Design of experiments is used to obtain data for capacitance and force using a commercial 3D boundary-element solver. Since accurate force values require significantly higher mesh refinement than accurate capacitance, we use numerical derivatives of capacitance values to compute the forces. The model is formulated such that the capacitance and force models use the same regression coefficients. The comb model thus obtained, fits the numerical capacitance data to within +/- 3% and force to within +/- 10%. The model is experimentally verified by measuring capacitance change in a specially designed test structure. The capacitance model matches measurements to within 10%. The comb model is implemented in an Analog Hardware Description Language (ADHL) for use in behavioral simulation of manufacturing variations in a CMOS-MEMS gyroscope.

  6. C14 Assays and Autoradiographic Studies on the Rooster Comb

    Science.gov (United States)

    Balazs, Endre A.; Szirmai, John A.; Bergendahl, Gudrun

    1959-01-01

    The distribution of C14 was studied in various parts of the rooster comb following treatment with testosterone. The value of gas-phase assay of C14 in tissue has been demonstrated and the results compared with those of autoradiographic studies on the same tissue. The results of these experiments showed that androgen treatment significantly increases the rate of incorporation of C14 in various parts of the comb. The specific activity of carbon in the comb, cornea, and liver differed, depending on which precursor, viz. glucose-6-C14, glucose-1-C14, and glucuronolactone-U-C14, was administered. The highest values were obtained after the administration of glucose-6-C14; glucuronolactone-U-C14 gave the lowest specific activity. The specific activity of carbon in different parts of the comb showed considerable variation. Carbon assay of serial sections of the comb cut at various planes showed that the specific activity of carbon was highest in the mucoid layer. Both C14 assays and autoradiograms indicate that C14 is also present in other parts of the comb. As seen in autoradiography, the concentration of C14 was highest in the epithelium, in the blood vessel walls, and in the avascular collagenous tissue. These results, and indications from previous studies, suggest that the high specific activity of carbon in the mucoid layer is due mainly to the presence of C14-labelled hyaluronic acid. Autoradiograms and PAS staining suggest that a significant amount of C14 is also incorporated into the glycoproteins associated with the collagen fibers. PMID:13654453

  7. Device Characterization of High Performance Quantum Dot Comb Laser

    KAUST Repository

    Rafi, Kazi

    2012-02-01

    The cost effective comb based laser sources are considered to be one of the prominent emitters used in optical communication (OC) and photonic integrated circuits (PIC). With the rising demand for delivering triple-play services (voice, data and video) in FTTH and FTTP-based WDM-PON networks, metropolitan area network (MAN), and short-reach rack-to-rack optical computer communications, a versatile and cost effective WDM transmitter design is required, where several DFB lasers can be replaced by a cost effective broadband comb laser to support on-chip optical signaling. Therefore, high performance quantum dot (Q.Dot) comb lasers need to satisfy several challenges before real system implementations. These challenges include a high uniform broadband gain spectrum from the active layer, small relative intensity noise with lower bit error rate (BER) and better temperature stability. Thus, such short wavelength comb lasers offering higher bandwidth can be a feasible solution to address these challenges. However, they still require thorough characterization before implementation. In this project, we briefly characterized the novel quantum dot comb laser using duty cycle based electrical injection and temperature variations where we have observed the presence of reduced thermal conductivity in the active layer. This phenomenon is responsible for the degradation of device performance. Hence, different performance trends, such as broadband emission and spectrum stability were studied with pulse and continuous electrical pumping. The tested comb laser is found to be an attractive solution for several applications but requires further experiments in order to be considered for photonic intergraded circuits and to support next generation computer-communications.

  8. Routes to spatiotemporal chaos in Kerr optical frequency combs.

    Science.gov (United States)

    Coillet, Aurélien; Chembo, Yanne K

    2014-03-01

    We investigate the various routes to spatiotemporal chaos in Kerr optical frequency combs, obtained through pumping an ultra-high Q-factor whispering-gallery mode resonator with a continuous-wave laser. The Lugiato-Lefever model is used to build bifurcation diagrams with regards to the parameters that are externally controllable, namely, the frequency and the power of the pumping laser. We show that the spatiotemporal chaos emerging from Turing patterns and solitons display distinctive dynamical features. Experimental spectra of chaotic Kerr combs are also presented for both cases, in excellent agreement with theoretical spectra.

  9. Fractional high-harmonic combs by attosecond-precision split-spectrum pulse control

    Directory of Open Access Journals (Sweden)

    Laux Martin

    2013-03-01

    Full Text Available Few-cycle laser fields enable pulse-shaping control of high-order harmonic generation by time delaying variable broadband spectral sections. We report the experimental generation of fractional (noninteger high-harmonic combs by the controlled interference of two attosecond pulse trains. Additionally the energy of the high harmonics is strongly tuned with the relative time delay. We quantify the tuning to directly result from the controlled variation of the instantaneous laser frequency at the shaped driver pulse intensity maximum.

  10. Two-photon direct frequency comb spectroscopy of alkali atoms

    Science.gov (United States)

    Palm, Christopher; Pradhananga, Trinity; Nguyen, Khoa; Montcrieffe, Caitlin; Kimball, Derek

    2012-11-01

    We have studied transition frequencies and excited state hyperfine structure in rubidium using 2-photon transitions excited directly with the frequency-doubled output of a erbium fiber optical frequency comb. The frequency comb output is directed in two counterpropagating directions through a vapor cell containing the rubidium vapor. A pair of optical filters is used to select teeth of the comb in order to identify the transition wavelengths. A photomultiplier tube (PMT) measures fluorescence from a decay channel wavelength selected with another optical filter. Using different combinations of filters enables a wide range of transitions to be investigated. By scanning the repetition rate, a Doppler-free spectrum can be obtained enabling kHz-resolution spectral measurements. An interesting dependence of the 2-photon spectrum on the energy of the intermediate state of the 2-photon transition is discussed. Our investigations are laying the groundwork for a long-term research program to use direct frequency comb spectroscopy to understand the complex spectra of rare-earth atoms.

  11. Femtosecond frequency comb based distance measurement in air

    NARCIS (Netherlands)

    Balling, P.; Kren, P.; Masika, P.; van den Berg, S.A.

    2009-01-01

    Interferometric measurement of distance using a femtosecond frequency comb is demonstrated and compared with a counting interferometer displacement measurement. A numerical model of pulse propagation in air is developed and the results are compared with experimental data for short distances. The

  12. Mechanisms behind the metabolic flexibility of an invasive comb jelly

    DEFF Research Database (Denmark)

    Augustine, Starrlight; Jaspers, Cornelia; Kooijman, Sebastiaan A. L.M.

    2014-01-01

    Mnemiopsis leidyi is an invasive comb jellywhich has successfully established itself in European seas. The species is known to produce spectacular blooms yet it is holoplanktonic and not much is known about its population dynamics in between. One way to gain insight on how M. leidyi might survive...

  13. Target micro-displacement measurement by a "comb" structure of intensity distribution in laser plasma propulsion

    Science.gov (United States)

    Zheng, Z. Y.; Zhang, S. Q.; Gao, L.; Gao, H.

    2015-05-01

    A "comb" structure of beam intensity distribution is designed and achieved to measure a target displacement of micrometer level in laser plasma propulsion. Base on the "comb" structure, the target displacement generated by nanosecond laser ablation solid target is measured and discussed. It is found that the "comb" structure is more suitable for a thin film target with a velocity lower than tens of millimeters per second. Combing with a light-electric monitor, the `comb' structure can be used to measure a large range velocity.

  14. The effect of drone comb on a honey bee colony's production of honey

    OpenAIRE

    Seeley , Thomas

    2002-01-01

    International audience; This study examined the impact on a colony's honey production of providing it with a natural amount (20%) of drone comb. Over 3 summers, for the period mid May to late August, I measured the weight gains of 10 colonies, 5 with drone comb and 5 without it. Colonies with drone comb gained only 25.2 $\\pm$ 16.0 kg whereas those without drone comb gained 48.8 $\\pm$ 14.8 kg. Colonies with drone comb also had a higher mean rate of drone flights and a lower incidence of drone ...

  15. Transfer of 13 species of the genus Burkholderia to the genus Caballeronia and reclassification of Burkholderia jirisanensis as Paraburkholderia jirisanensis comb. nov.

    Science.gov (United States)

    Dobritsa, Anatoly P; Linardopoulou, Elena V; Samadpour, Mansour

    2017-10-01

    A recent study of a group of Burkholderia glathei-like bacteria resulted in the description of 13 novel species of the genus Burkholderia. However, our analysis of phylogenetic positions of these species and their molecular signatures (conserved protein sequence indels) showed that they belong to the genus Caballeronia, and we propose to transfer them to this genus. The reclassified species names are proposed as Caballeroniaarationis comb. nov., Caballeroniaarvi comb. nov., Caballeroniacalidae comb. nov., Caballeroniacatudaia comb. nov., Caballeroniaconcitans comb. nov., Caballeroniafortuita comb. nov., Caballeroniaglebae comb. nov., Caballeroniahypogeia comb. nov., Caballeroniapedi comb. nov., Caballeroniaperedens comb. nov., Caballeroniaptereochthonis comb. nov., Caballeroniatemeraria comb. nov. and Caballeronia turbans comb. nov. It is also proposed to reclassify Burkholderia jirisanensis as Paraburkholderiajirisanensis comb. nov. Based on the results of the polyphasic study, B. jirisanensis had been described as a member of the A-group of the genus Burkholderiaand the most closely related to Burkholderia rhizosphaerae, Burkholderia humisilvae and Burkholderia solisilvae currently classified as belonging to the genus Paraburkholderia.

  16. Fast Interrogation of Fiber Bragg Gratings with Electro-Optical Dual Optical Frequency Combs

    Directory of Open Access Journals (Sweden)

    Julio E. Posada-Roman

    2016-11-01

    Full Text Available Optical frequency combs (OFC generated by electro-optic modulation of continuous-wave lasers provide broadband coherent sources with high power per line and independent control of line spacing and the number of lines. In addition to their application in spectroscopy, they offer flexible and optimized sources for the interrogation of other sensors based on wavelength change or wavelength filtering, such as fiber Bragg grating (FBG sensors. In this paper, a dual-OFC FBG interrogation system based on a single laser and two optical-phase modulators is presented. This architecture allows for the configuration of multimode optical source parameters such as the number of modes and their position within the reflected spectrum of the FBG. A direct read-out is obtained by mapping the optical spectrum onto the radio-frequency spectrum output of the dual-comb. This interrogation scheme is proposed for measuring fast phenomena such as vibrations and ultrasounds. Results are presented for dual-comb operation under optimized control. The optical modes are mapped onto detectable tones that are multiples of 0.5 MHz around a center radiofrequency tone (40 MHz. Measurements of ultrasounds (40 kHz and 120 kHz are demonstrated with this sensing system. Ultrasounds induce dynamic strain onto the fiber, which generates changes in the reflected Bragg wavelength and, hence, modulates the amplitude of the OFC modes within the reflected spectrum. The amplitude modulation of two counterphase tones is detected to obtain a differential measurement proportional to the ultrasound signal.

  17. Safe sex

    Science.gov (United States)

    ... sex; Sexually transmitted - safe sex; GC - safe sex; Gonorrhea - safe sex; Herpes - safe sex; HIV - safe sex; ... contact. STIs include: Chlamydia Genital herpes Genital warts Gonorrhea Hepatitis HIV HPV Syphilis STIs are also called ...

  18. Frequency comb generation by a continuous-wave-pumped optical parametric oscillator based on cascading quadratic nonlinearities.

    Science.gov (United States)

    Ulvila, Ville; Phillips, C R; Halonen, Lauri; Vainio, Markku

    2013-11-01

    We report optical frequency comb generation by a continuous-wave pumped optical parametric oscillator (OPO) without any active modulation. The OPO is configured as singly resonant with an additional nonlinear crystal (periodically poled MgO:LiNbO3) placed inside the OPO for phase mismatched second harmonic generation (SHG) of the resonating signal beam. The phase mismatched SHG causes cascading χ(2) nonlinearities, which can substantially increase the effective χ(3) nonlinearity in MgO:LiNbO3, leading to spectral broadening of the OPO signal beam via self-phase modulation. The OPO generates a stable 4 THz wide (-30 dB) frequency comb centered at 1.56 μm.

  19. Can neem oil help eliminate lice? Randomised controlled trial with and without louse combing

    Directory of Open Access Journals (Sweden)

    Christine M. Brown

    2017-06-01

    Full Text Available Background: Neem oil and wet combing with conditioner are both claimed to facilitate elimination of head louse infestation. The aim of this pilot study was to identify whether a 1% neem oil lotion showed activity itself and/or enhanced the effectiveness of combing in treating infestation. Methods: We treated 47 participants with 1% neem-based lotion on four occasions 3-4 days apart in a randomised, community based trial, analysed by intention to treat. The participants were randomly divided between two groups: One group used a grooming comb (placebo and the other a head louse detection and removal comb (wet combing with conditioner method to systematically comb the hair. Cure was defined as no lice on both Day 10 and Day 14. Results: The cure rates of 6/24 (25.0% for the placebo comb group and 8/23 (34.8% for the louse comb group were not significantly different. Conclusion: These results indicate that this formulation of neem oil was ineffective in the treatment of head louse infestations, even when accompanied by combing. Both combing methods were also ineffective, despite being implemented throughout by trained professionals.

  20. Additional gonorrhea and Chlamydia infections found with rapid follow-up screening in men who have sex with men with an indication for HIV postexposure prophylaxis

    NARCIS (Netherlands)

    de Vrieze, Nynke H. N.; van Rooijen, Martijn S.; van de Loeff, Maarten Schim; de Vries, Henry J. C.

    2014-01-01

    Sexually transmitted infection was found in 16.5% of the men who have sex with men with a postexposure prophylaxis indication. Chlamydia and gonorrhea screening was repeated after 14 days. Among those who were initially sexually transmitted infection negative, 4.1% had chlamydia or gonorrhea. In

  1. Nested folded-beam suspensions with low longitudinal stiffness for comb-drive actuators

    International Nuclear Information System (INIS)

    Hou, Max T; Huang, Ming-Xian; Chang, Chao-Min

    2014-01-01

    Nested folded-beam suspensions with a low longitudinal spring constant and a high lateral spring constant have been used in comb-drive actuators. In the new design, every two flexible beams and two stiff members form a parallelogram flexure, which is considered as an ‘element’ of the nested folded-beam suspension. A set of these flexures of increasing size were placed one outside another to compose a nested structure. In this way, a serial mechanical connection between adjacent parallelogram flexures was formed; thus, a longer output stroke was obtained by combining the stroke displacements of all flexures in an additive fashion. The designed suspensions were theoretically analyzed and numerically simulated. Furthermore, comb-drive actuators with conventional and new suspensions were fabricated and tested to verify the predicted function. In the testing cases, the longitudinal spring constants of suspensions with two (conventional), three and four parallelogram flexures on each side were measured as 2.77, 1.75 and 1.36 N m −1 . The ratio among these three values was approximately 6:4:3, which is consistent with the theoretical predictions and simulation results. Microfabricated folded beams in series were achieved. (paper)

  2. High-Q Bandpass Comb Filter for Mains Interference Extraction

    Directory of Open Access Journals (Sweden)

    Neycheva T.

    2009-12-01

    Full Text Available This paper presents a simple digital high-Q bandpass comb filter for power-line (PL or other periodical interference extraction. The filter concept relies on a correlated signal average resulting in alternating constructive and destructive spectrum interference i.e. the so-called comb frequency response. The presented filter is evaluated by Matlab simulations with real ECG signal contaminated with low amplitude PL interference. The made simulations show that this filter accurately extract the PL interference. It has high-Q notches only at PL odd harmonics and is appropriate for extraction of any kind of odd harmonic interference including rectangular shape. The filter is suitable for real-time operation with popular low-cost microcontrollers.

  3. Femtosecond frequency comb based distance measurement in air.

    Science.gov (United States)

    Balling, Petr; Kren, Petr; Masika, Pavel; van den Berg, S A

    2009-05-25

    Interferometric measurement of distance using a femtosecond frequency comb is demonstrated and compared with a counting interferometer displacement measurement. A numerical model of pulse propagation in air is developed and the results are compared with experimental data for short distances. The relative agreement for distance measurement in known laboratory conditions is better than 10(-7). According to the model, similar precision seems feasible even for long-distance measurement in air if conditions are sufficiently known. It is demonstrated that the relative width of the interferogram envelope even decreases with the measured length, and a fringe contrast higher than 90% could be obtained for kilometer distances in air, if optimal spectral width for that length and wavelength is used. The possibility of comb radiation delivery to the interferometer by an optical fiber is shown by model and experiment, which is important from a practical point of view.

  4. Comb mode filtering silver mirror cavity for spectroscopic distance measurement

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Radek; Hänsel, A.; Pravdová, Lenka; Sobota, Jaroslav; Číp, Ondřej; Bhattacharya, N.

    2016-01-01

    Roč. 87, č. 9 (2016), 093107:1-8 ISSN 0034-6748 R&D Projects: GA ČR(CZ) GPP102/12/P962; GA ČR GB14-36681G; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : optical frequency comb * femtosecond laser * long * air Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.515, year: 2016

  5. Generation of a frequency comb and applications thereof

    Science.gov (United States)

    Hagmann, Mark J; Yarotski, Dmitry A

    2013-12-03

    Apparatus for generating a microwave frequency comb (MFC) in the DC tunneling current of a scanning tunneling microscope (STM) by fast optical rectification, cause by nonlinearity of the DC current vs. voltage curve for the tunneling junction, of regularly-spaced, short pulses of optical radiation from a focused mode-locked, ultrafast laser, directed onto the tunneling junction, is described. Application of the MFC to high resolution dopant profiling in semiconductors is simulated. Application of the MFC to other measurements is described.

  6. Comb-e-Chem: an e-science research project

    OpenAIRE

    Frey, Jeremy G.

    2003-01-01

    The background to the Comb-e-Chem e-Science pilot project funded under the UK -Science Programme is presented and the areas being addresses within chemistry and more specifically combinatorial chemistry are disucssed. The ways in which the ideas underlying the application of computer technology can improve the production, analysis and dissemination of chemical information and knowledge in a collaborative environment are discussed.

  7. Practical system for the generation of pulsed quantum frequency combs.

    Science.gov (United States)

    Roztocki, Piotr; Kues, Michael; Reimer, Christian; Wetzel, Benjamin; Sciara, Stefania; Zhang, Yanbing; Cino, Alfonso; Little, Brent E; Chu, Sai T; Moss, David J; Morandotti, Roberto

    2017-08-07

    The on-chip generation of large and complex optical quantum states will enable low-cost and accessible advances for quantum technologies, such as secure communications and quantum computation. Integrated frequency combs are on-chip light sources with a broad spectrum of evenly-spaced frequency modes, commonly generated by four-wave mixing in optically-excited nonlinear micro-cavities, whose recent use for quantum state generation has provided a solution for scalable and multi-mode quantum light sources. Pulsed quantum frequency combs are of particular interest, since they allow the generation of single-frequency-mode photons, required for scaling state complexity towards, e.g., multi-photon states, and for quantum information applications. However, generation schemes for such pulsed combs have, to date, relied on micro-cavity excitation via lasers external to the sources, being neither versatile nor power-efficient, and impractical for scalable realizations of quantum technologies. Here, we introduce an actively-modulated, nested-cavity configuration that exploits the resonance pass-band characteristic of the micro-cavity to enable a mode-locked and energy-efficient excitation. We demonstrate that the scheme allows the generation of high-purity photons at large coincidence-to-accidental ratios (CAR). Furthermore, by increasing the repetition rate of the excitation field via harmonic mode-locking (i.e. driving the cavity modulation at harmonics of the fundamental repetition rate), we managed to increase the pair production rates (i.e. source efficiency), while maintaining a high CAR and photon purity. Our approach represents a significant step towards the realization of fully on-chip, stable, and versatile sources of pulsed quantum frequency combs, crucial for the development of accessible quantum technologies.

  8. Generation of Mid-Infrared Frequency Combs for Spectroscopic Applications

    Science.gov (United States)

    Maser, Daniel L.

    Mid-infrared laser sources prove to be a valuable tool in exploring a vast array of phenomena, finding their way into applications ranging from trace gas detection to X-ray generation and carbon dating. Mid-infrared frequency combs, in particular, are well-suited for many of these applications, owing to their inherent low-noise and broadband nature. Frequency comb technology is well-developed in the near-infrared as a result of immense technological development by the telecommunication industry in silica fiber and the existence of readily-available glass dopants such as ytterbium and erbium that enable oscillators at 1 and 1.5 ?m. However, options become substantially more limited at longer wavelengths, as silica is no longer transparent and the components required in a mid-infrared frequency comb system (oscillators, fibers, and both fiber and free-space components) are far less technologically mature. This thesis explores several different approaches to generating frequency comb sources in the mid-infrared region, and the development of sources used in the nonlinear processes implemented to reach these wavelengths. An optical parametric oscillator, two approaches to difference frequency generation, and nonlinear spectral broadening in chip-scale waveguides are developed, characterized, and spectroscopic potential for these techniques is demonstrated. The source used for these nonlinear processes, the erbium-doped fiber amplifier, is also studied and discussed throughout the design and optimization process. The nonlinear optical processes critical to this work are numerically modeled and used to confirm and predict experimental behavior.

  9. Comb-drive GaN micro-mirror on a GaN-on-silicon platform

    International Nuclear Information System (INIS)

    Wang, Yongjin; Sasaki, Takashi; Wu, Tong; Hu, Fangren; Hane, Kazuhiro

    2011-01-01

    We report here a double-sided process for the fabrication of a comb-drive GaN micro-mirror on a GaN-on-silicon platform. A silicon substrate is first patterned from the backside and removed by deep reactive ion etching, resulting in totally suspended GaN slabs. GaN microstructures including the torsion bars, movable combs and mirror plate are then defined on a freestanding GaN slab by the backside alignment technique and generated by fast atom beam etching with Cl 2 gas. Although the fabricated comb-drive GaN micro-mirrors are deflected by the residual stress in GaN thin films, they can operate on a high resistivity silicon substrate without introducing any additional isolation layer. The optical rotation angles are experimentally characterized in the rotation experiments. This work opens the possibility of producing GaN optical micro-electro-mechanical-system (MEMS) devices on a GaN-on-silicon platform.

  10. Self-corrected chip-based dual-comb spectrometer.

    Science.gov (United States)

    Hébert, Nicolas Bourbeau; Genest, Jérôme; Deschênes, Jean-Daniel; Bergeron, Hugo; Chen, George Y; Khurmi, Champak; Lancaster, David G

    2017-04-03

    We present a dual-comb spectrometer based on two passively mode-locked waveguide lasers integrated in a single Er-doped ZBLAN chip. This original design yields two free-running frequency combs having a high level of mutual stability. We developed in parallel a self-correction algorithm that compensates residual relative fluctuations and yields mode-resolved spectra without the help of any reference laser or control system. Fluctuations are extracted directly from the interferograms using the concept of ambiguity function, which leads to a significant simplification of the instrument that will greatly ease its widespread adoption and commercial deployment. Comparison with a correction algorithm relying on a single-frequency laser indicates discrepancies of only 50 attoseconds on optical timings. The capacities of this instrument are finally demonstrated with the acquisition of a high-resolution molecular spectrum covering 20 nm. This new chip-based multi-laser platform is ideal for the development of high-repetition-rate, compact and fieldable comb spectrometers in the near- and mid-infrared.

  11. Coherent combs in ionization by intense and short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Krajewska, K., E-mail: Katarzyna.Krajewska@fuw.edu.pl [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland); Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0299 (United States); Kamiński, J.Z., E-mail: Jerzy.Kaminski@fuw.edu.pl [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland)

    2016-03-22

    Photoionization of positive ions by a train of intense, short laser pulses is investigated within the relativistic strong field approximation, using the velocity gauge. The formation of broad peak structures in the high-energy domain of photoelectrons is observed and interpreted. The emergence of coherent photoelectron energy combs within these structures is demonstrated, and it is interpreted as the consequence of the Fraunhofer-type interference/diffraction of probability amplitudes of ionization from individual pulses comprising the train. Extensions to the coherent angular combs are also studied, and effects related to the radiation pressure are presented. - Highlights: • We develop relativistic Strong-Field Approximation for ionization by intense and short laser pulses of arbitrary spectral compositions. • We show that the consistent interpretation of results is provided by the Keldysh-type saddle point analysis of probability amplitudes. • We derive a general Fraunhofer-type interference/diffraction formula for finite train of pulses. • We study the coherent combs in photoelectron probability distributions.

  12. Dispersion compensated mid-infrared quantum cascade laser frequency comb with high power output

    Directory of Open Access Journals (Sweden)

    Q. Y. Lu

    2017-04-01

    Full Text Available Chromatic dispersion control plays an underlying role in optoelectronics and spectroscopy owing to its enhancement to nonlinear interactions by reducing the phase mismatching. This is particularly important to optical frequency combs based on quantum cascade lasers which require negligible dispersions for efficient mode locking of the dispersed modes into equally spaced comb modes. Here, we demonstrated a dispersion compensated mid-IR quantum cascade laser frequency comb with high power output at room temperature. A low-loss dispersive mirror has been engineered to compensate the device’s dispersion residue for frequency comb generation. Narrow intermode beating linewidths of 40 Hz in the comb-working currents were identified with a high power output of 460 mW and a broad spectral coverage of 80 cm-1. This dispersion compensation technique will enable fast spectroscopy and high-resolution metrology based on QCL combs with controlled dispersion and suppressed noise.

  13. Picometer-resolution dual-comb spectroscopy with a free-running fiber laser.

    Science.gov (United States)

    Zhao, Xin; Hu, Guoqing; Zhao, Bofeng; Li, Cui; Pan, Yingling; Liu, Ya; Yasui, Takeshi; Zheng, Zheng

    2016-09-19

    Dual-comb spectroscopy holds the promise as real-time, high-resolution spectroscopy tools. However, in its conventional schemes, the stringent requirement on the coherence between two lasers requires sophisticated control systems. By replacing control electronics with an all-optical dual-comb lasing scheme, a simplified dual-comb spectroscopy scheme is demonstrated using one dual-wavelength, passively mode-locked fiber laser. Pulses with a intracavity-dispersion-determined repetition-frequency difference are shown to have good mutual coherence and stability. Capability to resolve the comb teeth and a picometer-wide optical spectral resolution are demonstrated using a simple data acquisition system. Energy-efficient, free-running fiber lasers with a small comb-tooth-spacing could enable low-cost dual-comb systems.

  14. Reclassification of Enterobacter oryziphilus and Enterobacter oryzendophyticus as Kosakonia oryziphila comb. nov. and Kosakonia oryzendophytica comb. nov.

    Science.gov (United States)

    Li, Chun Yan; Zhou, Yuan Liang; Ji, Jing; Gu, Chun Tao

    2016-08-01

    The taxonomic positions of Enterobacter oryziphilus and Enterobacter oryzendophyticus were re-examined on the basis of concatenated partial rpoB, atpD, gyrB and infB gene sequence analysis. The reconstructed phylogenetic tree based upon concatenated partial rpoB, atpD, gyrB and infB gene sequences clearly showed that E. oryziphilus and E. oryzendophyticus and all defined species of the genus Kosakonia form a clade separate from other genera of the family Enterobacteriaceae, and, therefore, these species of the genus Enterobacter should be transferred to the genus Kosakonia. E. oryziphilus and E. oryzendophyticus are reclassified as K. oryziphila comb. nov. (type strain REICA_142T=LMG 26429T=NCCB 100393T) and K. oryzendophytica comb. nov. (type strain REICA_082T=LMG 26432T=NCCB 100390T), respectively.

  15. "Nail" and "comb" effects of cholesterol modified NIPAm oligomers on cancer targeting liposomes

    KAUST Repository

    Li, Wengang; Deng, Lin; Moosa, Basem; Wang, Guangchao; Mashat, Afnan; Khashab, Niveen M.

    2014-01-01

    Thermosensitive liposomes are a promising approach to controlled release and reduced drug cytotoxicity. Low molecular weight N-isopropylacrylamide (NIPAm) oligomers (NOs) with different architectures (main chain NOs (MCNOs) and side chain NOs (SCNOs)) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and radical polymerization and then separately used to prepare thermosensitive liposomes. A more controlled and enhanced release was observed for both NO liposomes compared to pristine ones. Two release mechanisms depending on the oligomer architecture, namely "nail" for MCNOs and "comb" for SCNOs, are proposed. In addition to thermosensitivity, the cancer targeting property of NO liposomes was achieved by further biotinylation of the delivery system. © The Royal Society of Chemistry.

  16. Physics of frequency-modulated comb generation in quantum-well diode lasers

    Science.gov (United States)

    Dong, Mark; Cundiff, Steven T.; Winful, Herbert G.

    2018-05-01

    We investigate the physical origin of frequency-modulated combs generated from single-section semiconductor diode lasers based on quantum wells, isolating the essential physics necessary for comb generation. We find that the two effects necessary for comb generation—spatial hole burning (leading to multimode operation) and four-wave mixing (leading to phase locking)—are indeed present in some quantum-well systems. The physics of comb generation in quantum wells is similar to that in quantum dot and quantum cascade lasers. We discuss the nature of the spectral phase and some important material parameters of these diode lasers.

  17. Spectral linewidth preservation in parametric frequency combs seeded by dual pumps.

    Science.gov (United States)

    Tong, Zhi; Wiberg, Andreas O J; Myslivets, Evgeny; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

    2012-07-30

    We demonstrate new technique for generation of programmable-pitch, wideband frequency combs with low phase noise. The comb generation was achieved using cavity-less, multistage mixer driven by two tunable continuous-wave pump seeds. The approach relies on phase-correlated continuous-wave pumps in order to cancel spectral linewidth broadening inherent to parametric comb generation. Parametric combs with over 200-nm bandwidth were obtained and characterized with respect to phase noise scaling to demonstrate linewidth preservation over 100 generated tones.

  18. Tadaridanema delicatus (Schwartz, 1927) n. gen., n. comb. (Trichostrongylina: Molineidae) parasite of Molossidae bats.

    Science.gov (United States)

    Falcón-Ordaz, Jorge; Guzmán-Cornejo, Carmen; García-Prieto, Luis; Gardner, Scott Lyell

    2006-10-01

    On the basis of the revision of the type material of Anoplostrongylus delicatus Schwartz, 1927, and new specimens collected from Tadarida brasiliensis mexicana (Saussure, 1860) in 4 arid localities from Mexico, we describe a new genus (Tadaridanema n. gen.), to which A. delicatus is transferred (as Tadaridanema delicatus (Schwartz, 1927) n. gen., n. comb.). This new genus differs from all other genera included in Anoplostrongylinae by having ray 2 larger than ray 3. In addition, T. delicatus can be differentiated from the type species of Anoplostrongylus (Anoplostrongylus paradoxus (Travassos, 1918)) because it possess vestibular branches equal in length, cephalic inflation divided into 2 regions, and synlophe with many small ridges at the midbody level, whereas in T. delicatus, vestibular branches are equal in size, cephalic inflation is simple in structure, and the synlophe has only 2 well-developed dorsal cuticular ridges.

  19. Generation of ultra-wide and flat optical frequency comb based on electro absorption modulator

    Science.gov (United States)

    Ujjwal; Thangaraj, Jaisingh

    2018-05-01

    A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb (OFC) based on serially cascading three stages of electro absorption modulators (EAMs) through sinusoidal radio frequency (RF) signals by setting frequencies at f GHz, f/2 GHz and f/4 GHz. Here, the first stage acts as subcarrier generator, the second stage acts as subcarrier doubler, and the third stage acts as subcarrier quadrupler. In addition, a higher number of subcarriers can easily be generated by adjusting the driving sinusoidal RF signal. In this paper, cascading three stages of EAMs driven by 50 GHz, 25 GHz and 12.5 GHz clock sources, we obtain 272 subcarriers with spacing of 2.5 GHz and power deviation within 1 dB. Theoretical analysis of serially cascaded EAMs for subcarrier generation is also investigated. Principal analysis and simulation of this technique are demonstrated.

  20. Band structure of comb-like photonic crystals containing meta-materials

    Science.gov (United States)

    Weng, Yi; Wang, Zhi-Guo; Chen, Hong

    2007-09-01

    We study the transmission properties and band structure of comb-like photonic crystals (PC) with backbones constructed of meta-materials (negative-index materials) within the frame of the interface response theory. The result shows the existence of a special band gap at low frequency. This gap differs from the Bragg gaps in that it is insensitive to the geometrical scaling and disorder. In comparison with the zero-average-index gap in one-dimensional PC made of alternating positive- and negative-index materials, the gap is obviously deeper and broader, given the same system parameters. In addition, the behavior of its gap-edges is also different. One gap-edge is decided by the average permittivity whereas the other is only subject to the changing of the permeability of the backbone. Due to this asymmetry of the two gap-edges, the broadening of the gap could be realized with much freedom and facility.

  1. Comb-Line Filter with Coupling Capacitor in Ground Plane

    Directory of Open Access Journals (Sweden)

    Toshiaki Kitamura

    2011-01-01

    Full Text Available A comb-line filter with a coupling capacitor in the ground plane is proposed. The filter consists of two quarter-wavelength microstrip resonators. A coupling capacitor is inserted into the ground plane in order to build strong coupling locally along the resonators. The filtering characteristics are investigated through numerical simulations as well as experiments. Filtering characteristics that have attenuation poles at both sides of the passband are obtained. The input susceptances of even and odd modes and coupling coefficients are discussed. The filters using stepped impedance resonators (SIRs are also discussed, and the effects of the coupling capacitor for an SIR structure are shown.

  2. Viscoelasticity and nonlinear simple shear flow behavior of an entangled asymmetric exact comb polymer solution

    KAUST Repository

    Snijkers, F.; Kirkwood, K. M.; Vlassopoulos, D.; Leal, L. G.; Nikopoulou, A.; Hadjichristidis, Nikolaos; Coppola, S.

    2016-01-01

    We report upon the characterization of the steady-state shear stresses and first normal stress differences as a function of shear rate using mechanical rheometry (both with a standard cone and plate and with a cone partitioned plate) and optical rheometry (with a flow-birefringence setup) of an entangled solution of asymmetric exact combs. The combs are polybutadienes (1,4-addition) consisting of an H-skeleton with an additional off-center branch on the backbone. We chose to investigate a solution in order to obtain reliable nonlinear shear data in overlapping dynamic regions with the two different techniques. The transient measurements obtained by cone partitioned plate indicated the appearance of overshoots in both the shear stress and the first normal stress difference during start-up shear flow. Interestingly, the overshoots in the start-up normal stress difference started to occur only at rates above the inverse stretch time of the backbone, when the stretch time of the backbone was estimated in analogy with linear chains including the effects of dynamic dilution of the branches but neglecting the effects of branch point friction, in excellent agreement with the situation for linear polymers. Flow-birefringence measurements were performed in a Couette geometry, and the extracted steady-state shear and first normal stress differences were found to agree well with the mechanical data, but were limited to relatively low rates below the inverse stretch time of the backbone. Finally, the steady-state properties were found to be in good agreement with model predictions based on a nonlinear multimode tube model developed for linear polymers when the branches are treated as solvent.

  3. Viscoelasticity and nonlinear simple shear flow behavior of an entangled asymmetric exact comb polymer solution

    KAUST Repository

    Snijkers, F.

    2016-03-31

    We report upon the characterization of the steady-state shear stresses and first normal stress differences as a function of shear rate using mechanical rheometry (both with a standard cone and plate and with a cone partitioned plate) and optical rheometry (with a flow-birefringence setup) of an entangled solution of asymmetric exact combs. The combs are polybutadienes (1,4-addition) consisting of an H-skeleton with an additional off-center branch on the backbone. We chose to investigate a solution in order to obtain reliable nonlinear shear data in overlapping dynamic regions with the two different techniques. The transient measurements obtained by cone partitioned plate indicated the appearance of overshoots in both the shear stress and the first normal stress difference during start-up shear flow. Interestingly, the overshoots in the start-up normal stress difference started to occur only at rates above the inverse stretch time of the backbone, when the stretch time of the backbone was estimated in analogy with linear chains including the effects of dynamic dilution of the branches but neglecting the effects of branch point friction, in excellent agreement with the situation for linear polymers. Flow-birefringence measurements were performed in a Couette geometry, and the extracted steady-state shear and first normal stress differences were found to agree well with the mechanical data, but were limited to relatively low rates below the inverse stretch time of the backbone. Finally, the steady-state properties were found to be in good agreement with model predictions based on a nonlinear multimode tube model developed for linear polymers when the branches are treated as solvent.

  4. Perovskites in the comb roof base of hornets : Their possible function

    NARCIS (Netherlands)

    Ishay, JS; Joseph, Z; Galushko, D; Ermakov, N; Bergman, DJ; Barkay, Z; Stokroos, [No Value; Van der Want, J

    2005-01-01

    On the ceiling of the Oriental hornet comb cell, there are mineral granules of poly-crystalline material known to belong to the group of perovskites. In a comb cell intended to house a worker hornet, the roof base usually carries one or several such perovskite granules containing titanium (Ti),

  5. MICROBIOLOGICAL COMPARISON BETWEEN HONEY IN JAR AND HONEY IN COMB FOR HUMAN CONSUMPTION

    Directory of Open Access Journals (Sweden)

    G. Formato

    2013-02-01

    Full Text Available The Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, during August-July 2007 analyzed, for the microbial aspects, 37 samples of jar honey and 53 samples of honey in comb obtained from 37 farms of Latium Region. In the jar honey there weren’t values up to 1*103 colony-forming unit (CFU/g of bacteria mesophiles, while in the honey in comb it was not up to 2*103 CFU/g. Bacillus cereus was found in 22 samples (41,5% of honey in comb and in 18 samples (48,6% of jar honey; Clostridium perfringens was found in 6 (11,3% samples of honey in comb and in 6 samples (16,2% of jar honey; Clostridium baratii was found in 1 (1,9% sample of honey in comb and in 1 sample (2,7% of jar honey; coagulase-positive staphylococci were found in 4 (11,3% samples of honey in comb and in 4 samples (10,8% of jar honey; Clostridium sordelli was found in 2 samples (3,8% of honey in comb and in 1 sample (2,7% of jar honey. Only 2 samples of honey in comb and 1 sample of jar honey had yeasts up to 1000 CFU/g. Finally, 9 samples (24,3% of jar honey and 16 samples (30,2% of honey in jar were positives for moulds.

  6. Optical fiber strain sensor using fiber resonator based on frequency comb Vernier spectroscopy

    DEFF Research Database (Denmark)

    Zhang, Liang; Lu, Ping; Chen, Li

    2012-01-01

    A novel (to our best knowledge) optical fiber strain sensor using a fiber ring resonator based on frequency comb Vernier spectroscopy is proposed and demonstrated. A passively mode-locked optical fiber laser is employed to generate a phased-locked frequency comb. Strain applied to the optical fib...

  7. Lévy processes on a generalized fractal comb

    Science.gov (United States)

    Sandev, Trifce; Iomin, Alexander; Méndez, Vicenç

    2016-09-01

    Comb geometry, constituted of a backbone and fingers, is one of the most simple paradigm of a two-dimensional structure, where anomalous diffusion can be realized in the framework of Markov processes. However, the intrinsic properties of the structure can destroy this Markovian transport. These effects can be described by the memory and spatial kernels. In particular, the fractal structure of the fingers, which is controlled by the spatial kernel in both the real and the Fourier spaces, leads to the Lévy processes (Lévy flights) and superdiffusion. This generalization of the fractional diffusion is described by the Riesz space fractional derivative. In the framework of this generalized fractal comb model, Lévy processes are considered, and exact solutions for the probability distribution functions are obtained in terms of the Fox H-function for a variety of the memory kernels, and the rate of the superdiffusive spreading is studied by calculating the fractional moments. For a special form of the memory kernels, we also observed a competition between long rests and long jumps. Finally, we considered the fractal structure of the fingers controlled by a Weierstrass function, which leads to the power-law kernel in the Fourier space. This is a special case, when the second moment exists for superdiffusion in this competition between long rests and long jumps.

  8. Lévy processes on a generalized fractal comb

    International Nuclear Information System (INIS)

    Sandev, Trifce; Iomin, Alexander; Méndez, Vicenç

    2016-01-01

    Comb geometry, constituted of a backbone and fingers, is one of the most simple paradigm of a two-dimensional structure, where anomalous diffusion can be realized in the framework of Markov processes. However, the intrinsic properties of the structure can destroy this Markovian transport. These effects can be described by the memory and spatial kernels. In particular, the fractal structure of the fingers, which is controlled by the spatial kernel in both the real and the Fourier spaces, leads to the Lévy processes (Lévy flights) and superdiffusion. This generalization of the fractional diffusion is described by the Riesz space fractional derivative. In the framework of this generalized fractal comb model, Lévy processes are considered, and exact solutions for the probability distribution functions are obtained in terms of the Fox H -function for a variety of the memory kernels, and the rate of the superdiffusive spreading is studied by calculating the fractional moments. For a special form of the memory kernels, we also observed a competition between long rests and long jumps. Finally, we considered the fractal structure of the fingers controlled by a Weierstrass function, which leads to the power-law kernel in the Fourier space. This is a special case, when the second moment exists for superdiffusion in this competition between long rests and long jumps. (paper)

  9. A Fine-Tooth Comb to Measure the Accelerating Universe

    Science.gov (United States)

    2008-09-01

    Astronomical instruments needed to answer crucial questions, such as the search for Earth-like planets or the way the Universe expands, have come a step closer with the first demonstration at the telescope of a new calibration system for precise spectrographs. The method uses a Nobel Prize-winning technology called a 'laser frequency comb', and is published in this week's issue of Science. Uncovering the disc ESO PR Photo 26a/08 A Laser Comb for Astronomy "It looks as if we are on the way to fulfil one of astronomers' dreams," says team member Theodor Hänsch, director at the Max Planck Institute for Quantum Optics (MPQ) in Germany. Hänsch, together with John Hall, was awarded the 2005 Nobel Prize in Physics for work including the frequency comb technique. Astronomers use instruments called spectrographs to spread the light from celestial objects into its component colours, or frequencies, in the same way water droplets create a rainbow from sunlight. They can then measure the velocities of stars, galaxies and quasars, search for planets around other stars, or study the expansion of the Universe. A spectrograph must be accurately calibrated so that the frequencies of light can be correctly measured. This is similar to how we need accurate rulers to measure lengths correctly. In the present case, a laser provides a sort of ruler, for measuring colours rather than distances, with an extremely accurate and fine grid. New, extremely precise spectrographs will be needed in experiments planned for the future European Extremely Large Telescope (E-ELT), which is being designed by ESO, the European Southern Observatory. These new spectrographs will need to be calibrated with even more accurate 'rulers'. In fact, they must be accurate to about one part in 30 billions - a feat equivalent to measuring the circumference of the Earth to about a millimetre! "We'll need something beyond what current technology can offer, and that's where the laser frequency comb comes in. It is

  10. Harnessing high-dimensional hyperentanglement through a biphoton frequency comb

    Science.gov (United States)

    Xie, Zhenda; Zhong, Tian; Shrestha, Sajan; Xu, Xinan; Liang, Junlin; Gong, Yan-Xiao; Bienfang, Joshua C.; Restelli, Alessandro; Shapiro, Jeffrey H.; Wong, Franco N. C.; Wei Wong, Chee

    2015-08-01

    Quantum entanglement is a fundamental resource for secure information processing and communications, and hyperentanglement or high-dimensional entanglement has been separately proposed for its high data capacity and error resilience. The continuous-variable nature of the energy-time entanglement makes it an ideal candidate for efficient high-dimensional coding with minimal limitations. Here, we demonstrate the first simultaneous high-dimensional hyperentanglement using a biphoton frequency comb to harness the full potential in both the energy and time domain. Long-postulated Hong-Ou-Mandel quantum revival is exhibited, with up to 19 time-bins and 96.5% visibilities. We further witness the high-dimensional energy-time entanglement through Franson revivals, observed periodically at integer time-bins, with 97.8% visibility. This qudit state is observed to simultaneously violate the generalized Bell inequality by up to 10.95 standard deviations while observing recurrent Clauser-Horne-Shimony-Holt S-parameters up to 2.76. Our biphoton frequency comb provides a platform for photon-efficient quantum communications towards the ultimate channel capacity through energy-time-polarization high-dimensional encoding.

  11. A Study of the Effect of the Fringe Fields on the Electrostatic Force in Vertical Comb Drives

    Directory of Open Access Journals (Sweden)

    Else Gallagher

    2014-10-01

    Full Text Available The equation that describes the relationship between the applied voltage and the resulting electrostatic force within comb drives is often used to assist in choosing the dimensions for their design. This paper re-examines how some of these dimensions—particularly the cross-sectional dimensions of the comb teeth—affect this relationship in vertical comb drives. The electrostatic forces in several vertical comb drives fabricated for this study were measured and compared to predictions made with four different mathematical models in order to explore the amount of complexity required within a model to accurately predict the electrostatic forces in the comb drives.

  12. Noise-Immune Cavity-Enhanced Optical Frequency Comb Spectroscopy

    Science.gov (United States)

    Rutkowski, Lucile; Khodabakhsh, Amir; Johanssson, Alexandra C.; Foltynowicz, Aleksandra

    2015-06-01

    We present noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS), a recently developed technique for sensitive, broadband, and high resolution spectroscopy. In NICE-OFCS an optical frequency comb (OFC) is locked to a high finesse cavity and phase-modulated at a frequency precisely equal to (a multiple of) the cavity free spectral range. Since each comb line and sideband is transmitted through a separate cavity mode in exactly the same way, any residual frequency noise on the OFC relative to the cavity affects each component in an identical manner. The transmitted intensity contains a beat signal at the modulation frequency that is immune to frequency-to-amplitude noise conversion by the cavity, in a way similar to continuous wave noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS). The light transmitted through the cavity is detected with a fast-scanning Fourier-transform spectrometer (FTS) and the NICE-OFCS signal is obtained by fast Fourier transform of the synchronously demodulated interferogram. Our NICE-OFCS system is based on an Er:fiber femtosecond laser locked to a cavity with a finesse of ˜9000 and a fast-scanning FTS equipped with a high-bandwidth commercial detector. We measured NICE-OFCS signals from the 3νb{1}+νb{3} overtone band of CO_2 around 1.57 μm and achieved absorption sensitivity 6.4×10-11cm-1 Hz-1/2 per spectral element, corresponding to a minimum detectable CO_2 concentration of 25 ppb after 330 s integration time. We will describe the principles of the technique and its technical implementation, and discuss the spectral lineshapes of the NICE-OFCS signals. A. Khodabakhsh, C. Abd Alrahman, and A. Foltynowicz, Opt. Lett. 39, 5034-5037 (2014). J. Ye, L. S. Ma, and J. L. Hall, J. Opt. Soc. Am. B 15, 6-15 (1998). A. Khodabakhsh, A. C. Johansson, and A. Foltynowicz, Appl. Phys. B (2015) doi:10.1007/s00340-015-6010-7.

  13. Highly fluorinated comb-shaped copolymer as proton exchange membranes (PEMs): Fuel cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Sik; Guiver, Michael D.; Ding, Jianfu [Institute for Chemical Process and Environmental Technology, National Research Council, 1200 Montreal Road, Ottawa, Ontario K1A 0R6 (Canada); Kim, Yu.Seung; Pivovar, Bryan S. [Materials Physics and Applications, Sensors and Electrochemical Devices Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2008-07-15

    The fuel cell performance (DMFC and H{sub 2}/air) of highly fluorinated comb-shaped copolymer is reported. The initial performance of membrane electrode assemblies (MEAs) fabricated from comb-shaped copolymer containing a side-chain weight fraction of 22% are compared with those derived from Nafion and sulfonated polysulfone (BPSH-35) under DMFC conditions. The low water uptake of comb copolymer enabled an increase in proton exchange site concentrations in the hydrated polymer, which is a desirable membrane property for DMFC application. The comb-shaped copolymer architecture induces phase separated morphology between the hydrophobic fluoroaromatic backbone and the polysulfonic acid side chains. The initial performance of the MEAs using BPSH-35 and Comb 22 copolymer were comparable and higher than that of the Nafion MEA at all methanol concentrations. For example, the power density of the MEA using Comb 22 copolymer at 350 mA cm{sup -2} and 0.5 M methanol was 145 mW cm{sup -2}, whereas the power densities of MEAs using BPSH-35 were 136 mW cm{sup -2}. The power density of the MEA using Comb 22 copolymer at 350 mA cm{sup -2} and 2.0 M methanol was 144.5 mW cm{sup -2}, whereas the power densities of MEAs using BPSH-35 were 143 mW cm{sup -2}. (author)

  14. Mid-infrared frequency comb via coherent dispersive wave generation in silicon nitride nanophotonic waveguides

    Science.gov (United States)

    Guo, Hairun; Herkommer, Clemens; Billat, Adrien; Grassani, Davide; Zhang, Chuankun; Pfeiffer, Martin H. P.; Weng, Wenle; Brès, Camille-Sophie; Kippenberg, Tobias J.

    2018-06-01

    Mid-infrared optical frequency combs are of significant interest for molecular spectroscopy due to the large absorption of molecular vibrational modes on the one hand, and the ability to implement superior comb-based spectroscopic modalities with increased speed, sensitivity and precision on the other hand. Here, we demonstrate a simple, yet effective, method for the direct generation of mid-infrared optical frequency combs in the region from 2.5 to 4.0 μm (that is, 2,500-4,000 cm-1), covering a large fraction of the functional group region, from a conventional and compact erbium-fibre-based femtosecond laser in the telecommunication band (that is, 1.55 μm). The wavelength conversion is based on dispersive wave generation within the supercontinuum process in an unprecedented large-cross-section silicon nitride (Si3N4) waveguide with the dispersion lithographically engineered. The long-wavelength dispersive wave can perform as a mid-infrared frequency comb, whose coherence is demonstrated via optical heterodyne measurements. Such an approach can be considered as an alternative option to mid-infrared frequency comb generation. Moreover, it has the potential to realize compact dual-comb spectrometers. The generated combs also have a fine teeth-spacing, making them suitable for gas-phase analysis.

  15. Ornamental comb colour predicts T-cell-mediated immunity in male red grouse Lagopus lagopus scoticus

    Science.gov (United States)

    Mougeot, Francois

    2008-02-01

    Sexual ornaments might reliably indicate the ability to cope with parasites and diseases, and a better ability to mount a primary inflammatory response to a novel challenge. Carotenoid-based ornaments are amongst the commonest sexual signals of birds and often influence mate choice. Because carotenoids are immuno-stimulants, signallers may trade-off allocating these to ornamental colouration or using them for immune responses, so carotenoid-based ornaments might be particularly useful as honest indicators of immuno-compentence. Tetraonid birds, such as the red grouse Lagopus lagopus scoticus, exhibit supra-orbital yellow red combs, a conspicuous ornament which functions in intra- and inter-sexual selection. The colour of combs is due to epidermal pigmentation by carotenoids, while their size is testosterone-dependent. In this study, I investigated whether comb characteristics, and in particular, comb colour, indicated immuno-competence in free-living male red grouse. I assessed T-cell-mediated immunity using a standardised challenge with phytohaemagglutinin. Red grouse combs reflect in the red and in the ultraviolet spectrum of light, which is not visible to humans but that grouse most likely see, so I measured comb colour across the whole bird visible spectrum (300 700 nm) using a reflectance spectrometer. I found that males with bigger and redder combs, but with less ultraviolet reflectance, had greater T-cell-mediated immune response. Comb colour predicted T-cell-mediated immune response better than comb size, indicating that the carotenoid-based colouration of this ornament might reliably signal this aspect of male quality.

  16. Sex Therapy

    Science.gov (United States)

    Sex therapy Overview Sex therapy is a type of psychotherapy — a general term for treating mental health problems by talking with a mental health professional. Through sex therapy, you can address concerns about sexual function, ...

  17. Reclassification of Bacillus marismortui as Salibacillus marismortui comb. nov.

    Science.gov (United States)

    Arahal, D R; Márquez, M C; Volcani, B E; Schleifer, K H; Ventosa, A

    2000-07-01

    Recently, the features of a group of strains isolated from Dead Sea enrichments obtained in 1936 by one of us (B. E. Volcani) were described. They were gram-positive, moderately halophilic, spore-forming rods, and were placed in a new species, Bacillus marismortui. At the same time, the new genus Salibacillus was proposed for the halophilic species Bacillus salexigens. B. marismortui and Salibacillus salexigens have similar phenotypic characteristics and the same peptidoglycan type. Phylogenetic analysis based on 16S rRNA sequence comparisons showed that they are sufficiently closely related (96.6% similarity) as to warrant placement in the same genus. However, DNA-DNA hybridization experiments showed that they constitute two separate species (41% DNA similarity). Therefore the reclassification of Bacillus marismortui as Salibacillus marismortui comb. nov. is proposed.

  18. Converse flexoelectric effect in comb electrode piezoelectric microbeam

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Zhiyuan, E-mail: shenyuan675603@gmail.com [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Chen, Wei [Microelectronics Centre, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore)

    2012-04-09

    We demonstrate the converse flexoelectric effect in a lead zirconate titanate microbeam. The fringe electric field of a comb electrode induces converse flexoelectric responses in uniformly poled and depoled beams. The simulated electric field distribution shows that bending of the beam is induced by piezoelectric and μ{sub 11}, μ{sub 12} flexoelectric coefficients. Simulations indicate that piezoelectric displacement occurs in different directions in the two opposite poled samples while flexoelectric displacement remains the same. This finding is verified by the displacement measurement results. -- Highlights: ► We demonstrate the converse flexoelectric effect in a PZT microbeam. ► Beams with upward and downward poling states are fabricated by MEMS technique. ► Converse flexoelectric deformation is induced by the fringe field. ► Electric field distribution is calculated by finite element analysis. ► The simulation results are verified by impedance and displacement measurements.

  19. Towards attosecond synchronization of remote mode-locked lasers using stabilized transmission of optical comb frequencies

    Science.gov (United States)

    Wilcox, R. B.; Byrd, J. M.; Doolittle, L. R.; Holzwarth, R.; Huang, G.

    2011-09-01

    We propose a method of synchronizing mode-locked lasers separated by hundreds of meters with the possibility of achieving sub-fs performance by locking the phases of corresponding lines in the optical comb spectrum. The optical phase from one comb line is transmitted to the remote laser over an interferometrically stabilized link by locking a single frequency laser to a comb line with high phase stability. We describe how these elements are integrated into a complete system and estimate the potential performance.

  20. Frequency Comb Driven Raman Transitions in the THz Range: High Precision Isotope Shift Measurements in Ca+

    DEFF Research Database (Denmark)

    Meyer, Steffen

    2017-01-01

    and frequency resolved optical gating (FROG) are used, and the two frequency comb systems used for the experiments are thoroughly characterized, a Coherent Mira Ti:sapph oscillator and a MenloSystems fiber based frequency comb system. The potential of frequency comb driven Raman transitions is shown...... transition frequencies typically are on the order of a few THz. High precision measurements on these ions have many intriguing applications, for example the test of time-variations of fundamental constants, ultracold chemistry on the quantum level, and quantum information and computing, to name just a few...

  1. Small-cell comb does not control Varroa mites in colonies of honeybees of European origin

    OpenAIRE

    Seeley , Thomas; Griffin , Sean

    2011-01-01

    International audience; We tested the idea that Varroa destructor can be controlled in colonies of the European subspecies of Apis mellifera by providing them with combs built of small cells, in which immature mites might have difficulty developing for lack of space. We established seven pairs of equal-size colonies that started out equally infested with mites. In each pair, one hive contained only standard-cell (5.4 mm) comb, and the other contained only small-cell (4.8 mm) comb. We measured...

  2. Sex Reversal in Birds.

    Science.gov (United States)

    Major, Andrew T; Smith, Craig A

    2016-01-01

    Sexual differentiation in birds is controlled genetically as in mammals, although the sex chromosomes are different. Males have a ZZ sex chromosome constitution, while females are ZW. Gene(s) on the sex chromosomes must initiate gonadal sex differentiation during embryonic life, inducing paired testes in ZZ individuals and unilateral ovaries in ZW individuals. The traditional view of avian sexual differentiation aligns with that expounded for other vertebrates; upon sexual differentiation, the gonads secrete sex steroid hormones that masculinise or feminise the rest of the body. However, recent studies on naturally occurring or experimentally induced avian sex reversal suggest a significant role for direct genetic factors, in addition to sex hormones, in regulating sexual differentiation of the soma in birds. This review will provide an overview of sex determination in birds and both naturally and experimentally induced sex reversal, with emphasis on the key role of oestrogen. We then consider how recent studies on sex reversal and gynandromorphic birds (half male:half female) are shaping our understanding of sexual differentiation in avians and in vertebrates more broadly. Current evidence shows that sexual differentiation in birds is a mix of direct genetic and hormonal mechanisms. Perturbation of either of these components may lead to sex reversal. © 2016 S. Karger AG, Basel.

  3. Phase noise characterization of a QD-based diode laser frequency comb.

    Science.gov (United States)

    Vedala, Govind; Al-Qadi, Mustafa; O'Sullivan, Maurice; Cartledge, John; Hui, Rongqing

    2017-07-10

    We measure, simultaneously, the phases of a large set of comb lines from a passively mode locked, InAs/InP, quantum dot laser frequency comb (QDLFC) by comparing the lines to a stable comb reference using multi-heterodyne coherent detection. Simultaneity permits the separation of differential and common mode phase noise and a straightforward determination of the wavelength corresponding to the minimum width of the comb line. We find that the common mode and differential phases are uncorrelated, and measure for the first time for a QDLFC that the intrinsic differential-mode phase (IDMP) between adjacent subcarriers is substantially the same for all subcarrier pairs. The latter observation supports an interpretation of 4.4ps as the standard deviation of IDMP on a 200µs time interval for this laser.

  4. Phase-locking to a free-space terahertz comb for metrological-grade terahertz lasers.

    Science.gov (United States)

    Consolino, L; Taschin, A; Bartolini, P; Bartalini, S; Cancio, P; Tredicucci, A; Beere, H E; Ritchie, D A; Torre, R; Vitiello, M S; De Natale, P

    2012-01-01

    Optical frequency comb synthesizers have represented a revolutionary approach to frequency metrology, providing a grid of frequency references for any laser emitting within their spectral coverage. Extending the metrological features of optical frequency comb synthesizers to the terahertz domain would be a major breakthrough, due to the widespread range of accessible strategic applications and the availability of stable, high-power and widely tunable sources such as quantum cascade lasers. Here we demonstrate phase-locking of a 2.5 THz quantum cascade laser to a free-space comb, generated in a LiNbO(3) waveguide and covering the 0.1-6 THz frequency range. We show that even a small fraction (quantum cascade laser is sufficient to generate a beat note suitable for phase-locking to the comb, paving the way to novel metrological-grade terahertz applications, including high-resolution spectroscopy, manipulation of cold molecules, astronomy and telecommunications.

  5. Dual comb generation from a mode-locked fiber laser with orthogonally polarized interlaced pulses.

    Science.gov (United States)

    Akosman, Ahmet E; Sander, Michelle Y

    2017-08-07

    Ultra-high precision dual-comb spectroscopy traditionally requires two mode-locked, fully stabilized lasers with complex feedback electronics. We present a novel mode-locked operation regime in a thulium-holmium co-doped fiber laser, a frequency-halved state with orthogonally polarized interlaced pulses, for dual comb generation from a single source. In a linear fiber laser cavity, an ultrafast pulse train composed of co-generated, equal intensity and orthogonally polarized consecutive pulses at half of the fundamental repetition rate is demonstrated based on vector solitons. Upon optical interference of the orthogonally polarized pulse trains, two stable microwave RF beat combs are formed, effectively down-converting the optical properties into the microwave regime. These co-generated, dual polarization interlaced pulse trains, from one all-fiber laser configuration with common mode suppression, thus provide an attractive compact source for dual-comb spectroscopy, optical metrology and polarization entanglement measurements.

  6. Nonlinear dynamics of spring softening and hardening in folded-mems comb drive resonators

    KAUST Repository

    Elshurafa, Amro M.; Khirallah, Kareem; Tawfik, Hani H.; Emira, Ahmed; Abdel Aziz, Ahmed K S; Sedky, Sherif M.

    2011-01-01

    This paper studies analytically and numerically the spring softening and hardening phenomena that occur in electrostatically actuated microelectromechanical systems comb drive resonators utilizing folded suspension beams. An analytical expression

  7. Robust Frequency Combs and Lasers for Optical Clocks and Sensing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical frequency combs are the key enabling technology that enabled the immense fractional stability of highly-stabilized lasers in the optical regime to be...

  8. Efficient frequency comb generation in AlGaAs-on-insulator

    DEFF Research Database (Denmark)

    Pu, Minhao; Ottaviano, Luisa; Semenova, Elizaveta

    2016-01-01

    The combination of nonlinear and integrated photonics enables Kerr frequency comb generation in stable chip-based microresonators. Such a comb system will revolutionize applications, including multi-wavelength lasers, metrology, and spectroscopy. Aluminum gallium arsenide (AlGaAs) exhibits very...... high material nonlinearity and low nonlinear loss. However, difficulties in device processing and low device effective nonlinearity made Kerr frequency comb generation elusive. Here, we demonstrate AlGaAs-on-insulator as a nonlinear platform at telecom wavelengths with an ultra-high device nonlinearity....... We show high-quality-factor (Q > 105) micro-resonators where optical parametric oscillations are achieved with milliwatt-level pump threshold powers, which paves the way for on-chip pumped comb generation....

  9. DWDM Fiber-Wireless Access System with Centralized Optical Frequency Comb-based RF Carrier Generation

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Beltrán, Marta; Sánchez, José

    2013-01-01

    We propose and experimentally demonstrate an optical wireless DWDM system at 60 GHz with optical incoherent heterodyne up-conversion using an optical frequency comb. Multiple users with wireline and wireless services are simultaneously supported....

  10. Comparative Flight Activities and Pathogen Load of Two Stocks of Honey Bees Reared in Gamma-Irradiated Combs

    Directory of Open Access Journals (Sweden)

    Lilia I. de Guzman

    2017-11-01

    Full Text Available Gamma irradiation is known to inactivate various pathogens that negatively affect honey bee health. Bee pathogens, such as Deformed wing virus (DWV and Nosema spp., have a deleterious impact on foraging activities and bee survival, and have been detected in combs. In this study, we assessed the effects of gamma irradiation on the flight activities, pathogen load, and survival of two honey bee stocks that were reared in irradiated and non-irradiated combs. Overall, bee genotype influenced the average number of daily flights, the total number of foraging flights, and total flight duration, in which the Russian honey bees outperformed the Italian honey bees. Exposing combs to gamma irradiation only affected the age at first flight, with worker bees that were reared in non-irradiated combs foraging prematurely compared to those reared in irradiated combs. Precocious foraging may be associated with the higher levels of DWV in bees reared in non-irradiated combs and also with the lower amount of pollen stores in colonies that used non-irradiated combs. These data suggest that gamma irradiation of combs can help minimize the negative impact of DWV in honey bees. Since colonies with irradiated combs stored more pollen than those with non-irradiated combs, crop pollination efficiency may be further improved when mite-resistant stocks are used, since they performed more flights and had longer flight durations.

  11. Broadband high-resolution two-photon spectroscopy with laser frequency combs

    OpenAIRE

    Hipke, Arthur; Meek, Samuel A.; Ideguchi, Takuro; Hänsch, Theodor W.; Picqué, Nathalie

    2013-01-01

    Two-photon excitation spectroscopy with broad spectral span is demonstrated at Doppler-limited resolution. We describe first Fourier transform two-photon spectroscopy of an atomic sample with two mode-locked laser oscillators in a dual-comb technique. Each transition is uniquely identified by the modulation imparted by the interfering comb excitations. The temporal modulation of the spontaneous two-photon fluorescence is monitored with a single photodetector, and the spectrum is revealed by a...

  12. Broadband Doppler-limited two-photon and stepwise excitation spectroscopy with laser frequency combs

    Science.gov (United States)

    Hipke, Arthur; Meek, Samuel A.; Ideguchi, Takuro; Hänsch, Theodor W.; Picqué, Nathalie

    2014-07-01

    Multiplex two-photon excitation spectroscopy is demonstrated at Doppler-limited resolution. We describe first Fourier-transform two-photon spectroscopy of an atomic sample with two mode-locked laser oscillators in a dual-comb technique. Each transition is uniquely identified by the modulation imparted by the interfering comb excitations. The temporal modulation of the spontaneous two-photon fluorescence is monitored with a single photodetector, and the spectrum of all excited transitions is revealed by a Fourier transform.

  13. Refractive-index-sensing radio-frequency comb with intracavity multi-mode interference fibre sensor

    OpenAIRE

    Oe, Roy; Taue, Shuji; Minamikawa, Takeo; Nagai, Kosuke; Mizutani, Yasuhiro; Iwata, Tetsuo; Yamamoto, Hirotsugu; Fukano, Hideki; Nakajima, Yoshiaki; Minoshima, Kaoru; Yasui, Takeshi

    2018-01-01

    Optical frequency combs have attracted attention as optical frequency rulers due to their tooth-like discrete spectra together with their inherent mode-locking nature and phase-locking control to a frequency standard. Based on this concept, their applications until now have been demonstrated in the fields of optical frequency metrology and optical distance metrology. However, if the utility of optical combs can be further expanded beyond their optical-frequency-ruler-based application by expl...

  14. Effect of polycarboxylate ether comb-type polymer on viscosity and interfacial properties of kaolinite clay suspensions.

    Science.gov (United States)

    Zhang, Ling; Lu, Qingye; Xu, Zhenghe; Liu, Qingxia; Zeng, Hongbo

    2012-07-15

    The interactions between kaolinite clay particles and a comb-type polymer (polycarboxylate ether or PCE), so-called PCE super-plasticizer, were investigated through viscosity and surface forces measurements by a rheometer and a Surface Forces Apparatus (SFA). The addition of PCE shows a strong impact on the viscosity of concentrated kaolinite suspensions in alkaline solutions (pH=8.3) but a weak effect under acidic conditions (pH=3.4). In acidic solutions, the high viscosity measured is attributed to the strong electrostatic interaction between negatively charged basal planes and positively charged edge surfaces of clay particles. Under the alkaline condition, the suspension viscosity was found to first increase significantly and then decrease with increasing PCE dosages. The results from surface forces measurement show that PCE molecules at low dosages can bridge the kaolinite particles in the concentrated suspensions via hydrogen bonding, leading to the formation of a kaolinite-PCE "network" and hence an increased suspension viscosity. At high PCE dosages, clay particles are fully covered by PCE molecules, leading to a more dispersed kaolinite suspensions and hence lower suspension viscosity due to steric repulsion between the adsorbed PCE molecules. The insights derived from measuring viscosity and interfacial properties of kaolinite suspensions containing varying amount of comb-type super-plasticizer PCE at different pH provide the foundation for many engineering applications and optimizing industrial processes. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Optical frequency comb for high resolution hydrogen spectroscopy

    International Nuclear Information System (INIS)

    Arnoult, O.

    2006-11-01

    In this work, we perform an absolute frequency measurement of the 1S-3S transition in atomic hydrogen, in order to improve the uncertainties on both the Rydberg constant and the Lamb shift L1S. In the experiment, a CW stabilized Ti:Sa laser is doubled twice in LBO (LiB 3 O 5 ) and BBO (β-BaB 2 O 4 ) crystals. The 1S-3S transition is excited by two photons at 205 nm in an optical cavity colinear with the atomic beam, at room temperature. The remaining second-order Doppler effect is compensated by a quadratic Stark effect resulting from an applied static magnetic field. An optical frequency comb is used to compare directly the Ti:Sa frequency with the microwave frequency standard. We detect fluorescence at 656 nm thanks to a CCD camera. Fitting the experimental data with our calculated line shapes leads to a value of the second-order Doppler effect in disagreement with approximative predictions for the 1S-3S frequency. We suggest the existence of stray electric fields as a possible systematic effect. The slides of the defence of the thesis have been added at the end of the document. (author)

  16. Dual-etalon, cavity-ring-down, frequency comb spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Strecker, Kevin E.; Chandler, David W.

    2010-10-01

    The 'dual etalon frequency comb spectrometer' is a novel low cost spectometer with limited moving parts. A broad band light source (pulsed laser, LED, lamp ...) is split into two beam paths. One travels through an etalon and a sample gas, while the second arm is just an etalon cavity, and the two beams are recombined onto a single detector. If the free spectral ranges (FSR) of the two cavities are not identical, the intensity pattern at the detector with consist of a series of heterodyne frequencies. Each mode out of the sample arm etalon with have a unique frequency in RF (radio-frequency) range, where modern electronics can easily record the signals. By monitoring these RF beat frequencies we can then determine when an optical frequencies is absorbed. The resolution is set by the FSR of the cavity, typically 10 MHz, with a bandwidth up to 100s of cm{sup -1}. In this report, the new spectrometer is described in detail and demonstration experiments on Iodine absorption are carried out. Further we discuss powerful potential next generation steps to developing this into a point sensor for monitoring combustion by-products, environmental pollutants, and warfare agents.

  17. Spatially-Scanned Dual Comb Spectroscopy for Atmospheric Measurements

    Science.gov (United States)

    Cossel, K.; Waxman, E.; Giorgetta, F.; Cermak, M.; Coddington, I.; Hesselius, D.; Ruben, S.; Swann, W.; Rieker, G. B.; Newbury, N.

    2017-12-01

    Measuring trace gas emissions from sources that are spatially complex and temporally variable, such as leaking natural gas infrastructure, is challenging with current measurement systems. Here, we present a new technique that provides the path-integrated concentrations of multiple gas species between a ground station and a retroreflector mounted on a small quadcopter. Such a system could provide the ability to quantify small area emissions sources as well measure vertical mixing within the boundary layer. The system is based on a near-infrared dual frequency-comb spectroscopy system (DCS) covering 1.58-1.7 microns, which enables rapid, accurate measurements of CO2, CH4, H2O, and HDO. The eye-safe laser light is launched from a telescope on a fast azimuth, elevation gimbal to a small quadcopter carrying a lightweight retroreflector as well as a high-precision real-time kinematic GPS receiver (for real-time cm-level path length measurements) and pressure, temperature and humidity sensors. Here, we show the results of test measurements from controlled releases of CH4 as well as from test vertical profiles.

  18. Unidirectional, dual-comb lasing under multiple pulse formation mechanisms in a passively mode-locked fiber ring laser

    OpenAIRE

    Liu, Ya; Zhao, Xin; Hu, Guoqing; Li, Cui; Zhao, Bofeng; Zheng, Zheng

    2016-01-01

    Dual-comb lasers from which asynchronous ultrashort pulses can be simultaneously generated have recently become an interesting research subject. They could be an intriguing alternative to the current dual-laser optical-frequency-comb source with highly sophisticated electronic control systems. If generated through a common light path traveled by all pulses, the common-mode noises between the spectral lines of different pulse trains could be significantly reduced. Therefore, coherent dual-comb...

  19. Efficient On-chip Optical Microresonator for Optical Comb Generation: Design and Fabrication

    Science.gov (United States)

    Han, Kyunghun

    An optical frequency comb is a series of equally spaced frequency components. It has gained much attention since Nobel physics prize was awarded John L. Hall and Theodor W. Hansch for their contribution to the optical frequency comb technique in 2005. The optical frequency comb has been extensively studied because of its precision as a tool for spectroscopy, and is now widely used in bio- and chemical sensors, optical clocks, mode-locked dark pulse generation, soliton generation, and optical communication. Recently, thanks to the developments in nanotechnology, the optical frequency comb generation is made possible at a chip-scale level with microresonators. However, because the threshold power of the optical frequency comb generation is beyond the capability of the on-chip laser source, efficient microresonator is required. Here, we demonstrate an ultra-compact and highly efficient strip-slot direct mode coupler, aiming to achieve slotted silicon microresonator cladded with nonlinear polymer Poly-DDMEBT in SOI platform. As an application of the strip-slot direct mode coupling, a double slot fiber-to-chip edge coupler is demonstrated showing 2 dB insertion loss reduction compared to the conventional single tip edge coupler. For silicon nitride platform, we investigated evanescent wave coupling of microresonator, focusing on bus waveguide geometry optimization. The optimized waveguide width offers an efficient excitation of a fundamental mode in the resonator waveguide. This investigation can benefit low threshold comb generation by enhancing the extinction ratio. We experimentally demonstrated the high Q-factor micro-ring resonator with intrinsic Q of 12.6 million as well as the single FSR comb generation with 63 mW.

  20. Seasonal recruitment and survival strategies of Palisada cervicornis comb. nov. (Ceramiales, Rhodophyta) in coral reefs.

    Science.gov (United States)

    Collado-Vides, Ligia; Duran, Alain; Armenis, Elizabeth; Cassano, Valéria; Burkepile, Deron; Shantz, Andrew A; Palma, Laura; Díaz-Larrea, Jhoana; Sentíes, Abel; Fujii, Mutue Toyota

    2017-10-01

    As marine tropical ecosystems deteriorate and lose biodiversity, their communities are shifting to being dominated by a few species, altering ecosystem's functioning and services. Macroalgae are becoming dominant on coral reefs, and are frequently observed outcompeting corals. Turf algal assemblages are the base of energy flow in these systems and one of the most abundant types of macroalgae on coral reefs, but little is known about their biology and diversity. Through molecular and morphological analyses, we identified the turf-forming species Laurencia cervicornis, and by studying seasonal recruitment and the impact of herbivorous fishes on its abundance, we describe its survival strategy. The molecular analyses used a total of 45 rbcL gene sequences including eight current genera within the Laurencia complex and two new sequences of L. cervicornis and strongly support the new combination of Palisada cervicornis comb. nov. In addition, a detailed morphological characterization including the description of reproductive structures is provided. Palisada cervicornis was seen recruiting in all seasons but was typically in low abundance. Specimens grown on tiles in fish exclosure cages were devoured in less than 4 h when offered to fishes. Even though many species of the Laurencia complex have chemicals that deter herbivory, species within the genus Palisada lack feeding deterrents and thus are highly palatable. We suggest that P. cervicornis is a palatable species that seems to survive in the community by obtaining a size-refuge from herbivory within turf communities. © 2017 Phycological Society of America.

  1. Tunable and broadband microwave frequency combs based on a semiconductor laser with incoherent optical feedback

    International Nuclear Information System (INIS)

    Zhao Mao-Rong; Wu Zheng-Mao; Deng Tao; Zhou Zhen-Li; Xia Guang-Qiong

    2015-01-01

    Based on a semiconductor laser (SL) with incoherent optical feedback, a novel all-optical scheme for generating tunable and broadband microwave frequency combs (MFCs) is proposed and investigated numerically. The results show that, under suitable operation parameters, the SL with incoherent optical feedback can be driven to operate at a regular pulsing state, and the generated MFCs have bandwidths broader than 40 GHz within a 10 dB amplitude variation. For a fixed bias current, the line spacing (or repetition frequency) of the MFCs can be easily tuned by varying the feedback delay time and the feedback strength, and the tuning range of the line spacing increases with the increase in the bias current. The linewidth of the MFCs is sensitive to the variation of the feedback delay time and the feedback strength, and a linewidth of tens of KHz can be achieved through finely adjusting the feedback delay time and the feedback strength. In addition, mappings of amplitude variation, repetition frequency, and linewidth of MFCs in the parameter space of the feedback delay time and the feedback strength are presented. (paper)

  2. Sex Headaches

    Science.gov (United States)

    Sex headaches Overview Sex headaches are brought on by sexual activity — especially an orgasm. You may notice a dull ache in your head ... severe headache just before or during orgasm. Most sex headaches are nothing to worry about. But some ...

  3. Low Noise Frequency Comb Sources Based on Synchronously Pumped Doubly Resonant Optical Parametric Oscillators

    Science.gov (United States)

    Wan, Chenchen

    Optical frequency combs are coherent light sources consist of thousands of equally spaced frequency lines. Frequency combs have achieved success in applications of metrology, spectroscopy and precise pulse manipulation and control. The most common way to generate frequency combs is based on mode-locked lasers which has the output spectrum of comb structures. To generate stable frequency combs, the output from mode-locked lasers need to be phase stabilized. The whole comb lines will be stabilized if the pulse train repetition rate corresponding to comb spacing and the pulse carrier envelope offset (CEO) frequency are both stabilized. The output from a laser always has fluctuations in parameters known as noise. In laser applications, noise is an important factor to limit the performance and often need to be well controlled. For example in precision measurement such as frequency metrology and precise spectroscopy, low laser intensity and phase noise is required. In mode-locked lasers there are different types of noise like intensity noise, pulse temporal position noise also known as timing jitter, optical phase noise. In term for frequency combs, these noise dynamics is more complex and often related. Understanding the noise behavior is not only of great interest in practical applications but also help understand fundamental laser physics. In this dissertation, the noise of frequency combs and mode-locked lasers will be studied in two projects. First, the CEO frequency phase noise of a synchronously pumped doubly resonant optical parametric oscillators (OPO) will be explored. This is very important for applications of the OPO as a coherent frequency comb source. Another project will focus on the intensity noise coupling in a soliton fiber oscillator, the finding of different noise coupling in soliton pulses and the dispersive waves generated from soliton perturbation can provide very practical guidance for low noise soliton laser design. OPOs are used to generate

  4. The ability of White Leghorn hens with trimmed comb and wattles to thermoregulate.

    Science.gov (United States)

    Al-Ramamneh, D S; Makagon, M M; Hester, P Y

    2016-08-01

    It is estimated that each year over 19 million pullets in the United States have their combs partially trimmed at a young age to improve egg production and feed efficiency. A possible disadvantage of trimming is that the comb and wattles may be essential for thermoregulation during hot weather allowing for conductive cooling of the blood through vasodilation of superficial vessels in these integumentary tissues. The objective of this study was to investigate the effects of partial comb and wattle removal, performed at 21 d of age, on the ability of White Leghorns to thermoregulate before, during, and after an imposed heating episode that averaged 34.6°C for 50.5 h. An increase in mortality at 20 h and body temperature at 48 h post initiation of the heating episode demonstrated that hens with trimmed comb and wattles were not able to cope with heat stress as effectively as controls. The increase in wattle temperature in controls as compared to trimmed hens during the heating episode and following heat stress provides supportive evidence that blood pools to the peripheral surface for conductive heat loss. During high temperatures typical of summer, trimmed hens attempted to compensate for their lack of ability to transfer heat from their comb and wattles to the environment through increased proportion of panting and wing spreading. Under less extreme conditions with lowered ambient temperatures, the trimming of the comb and wattles did not impair the ability of hens to thermoregulate, as body temperatures and behavior were similar to controls with no mortality. Egg weight was the only production parameter adversely affected by the trimming of the comb and wattles as compared to controls. The implication is that hens need their combs and wattles to thermoregulate effectively during periods of high environmental temperature. Pullets should not be subjected to a comb and wattle trim if they are housed in laying facilities that are not appropriately cooled during the

  5. A novel vertical comb-drive electrostatic actuator using a one layer process

    International Nuclear Information System (INIS)

    Hailu, Zewdu; He, Siyuan; Mrad, Ridha Ben

    2014-01-01

    This paper presents the design, fabrication and testing of a new residual stress gradient based vertical comb-drive actuator. Conventional vertical comb-drive actuators need two structural layers, i.e. one for the moving fingers and a second for the fixed fingers. A vertical comb-drive actuator based on a single structural layer micromachining process, using the residual stress gradient along the thickness of the nickel of the MetalMUMPs (Metal Multi-User MEMS process) fabrication process, is developed. The MetalMUMPs provides a 20 μm thick nickel film and is subject to residual stress gradients along its thickness. Two curve-up beams are devised to curve out of plane after release. The curve-up beams raise a plate with comb fingers above the substrate to form the moving fingers. The fixed comb fingers are connected to the substrate via anchors. When a voltage is applied across the moving and the fixed fingers, the moving fingers move down towards the fixed fingers. Experimental measurements on prototypes have verified the design principle. A vertical displacement of 4.81 µm at 150 V was measured. (paper)

  6. Preparation and Photoluminescence of ZnO Comb-Like Structure and Nanorod Arrays

    Science.gov (United States)

    Yin, Song; Chen, Yi-qing; Su, Yong; Zhou, Qing-tao

    2007-06-01

    A large quantity of Zinc oxide (ZnO) comb-like structure and high-density well-aligned ZnO nanorod arrays were prepared on silicon substrate via thermal evaporation process without any catalyst. The morphology, growth mechanism, and optical properties of the both structures were investigated using XRD, SEM, TEM and PL. The resulting comb-teeth, with a diameter about 20 nm, growing along the [0001] direction have a well-defined epitaxial relationship with the comb ribbon. The ZnO nanorod arrays have a diameter about 200 nm and length up to several micrometers growing approximately vertical to the Si substrate. A ZnO film was obtained before the nanorods growth. A growth model is proposed for interpreting the growth mechanism of comb-like zigzag-notch nanostructure. Room temperature photoluminescence measurements under excitation wavelength of 325 nm showed that the ZnO comb-like nanostructure has a weak UV emission at around 384 nm and a strong green emission around 491 nm, which correspond to a near band-edge transition and the singly ionized oxygen vacancy, respectively. In contrast, a strong and sharp UV peak and a weak green peak was obtained from the ZnO nanorod arrays.

  7. Histological responses of cutaneous vascular lesions following photodynamic therapy with talaporfin sodium: a chicken comb model.

    Science.gov (United States)

    Ohshiro, Takafumi; Nakajima, Tatsuo; Ogata, Hisao; Kishi, Kazuo

    2009-09-01

    Mono-L-aspartyl chlorin e6 (Talaporfin sodium) is a novel photosensitizer, and is currently being used in photodynamic therapy for various malignant tumors in combination with irradiation with a 664 nm laser. An interesting characteristic of Talaporfin sodium is that the skin photosensitivity after injection of this agent disappears faster than any other existing photosensitizers. This study examined the vascular events that occurred postirradiation in the chicken comb as a capillary malformation model after photosensitization with Talaporfin sodium. A single intravenous bolus injections of Talaporfin sodium was administered to the chickens, and a 1 cm diameter area of the comb of each animal was irradiated with a 664 nm visible red laser. The gross changes in the chicken combs were recorded for 7-14 days after photodynamic therapy. For the histological examination, HE, PTAH and Azan stained sections were analyzed. All treated chicken combs had blanched after photodynamic therapy. Microscopy demonstrated an absence of erythrocytes and the vessel lumina were obliterated, leaving the normal overlying epidermis completely intact. Concomitantly with selective destruction of the capillaries in the target area, moderate invasion of inflammatory cells and a slight increase in the stroma were observed. In the chicken comb model, photodynamic therapy with Talaporfin sodium effectively achieved selective destruction of the microvasculature while leaving the epidermis intact. Our results strongly suggest that photodynamic therapy with Talaporfin sodium could be a feasible method to treat dermal hypervascular lesions.

  8. Influence of Wheat-Milled Products and Their Additive Blends on Pasta Dough Rheological, Microstructure, and Product Quality Characteristics

    Directory of Open Access Journals (Sweden)

    B. Dhiraj

    2013-01-01

    Full Text Available This study is aimed to assess the suitability of T. aestivum wheat milled products and its combinations with T. durum semolina with additives such as ascorbic acid, vital gluten and HPMC (Hydroxypropyl methyl cellulose for pasta processing quality characteristics such as pasta dough rheology, microstructure, cooking quality, and sensory evaluation. Rheological studies showed maximum dough stability in Comb1 (T. aestivum wheat flour and semolina. Colour and cooking quality of Comb2 (T. durum semolina and T. aestivum wheat flour and Comb3 (T. aestivum wheat semolina and T. durum semolina were comparable with control. Pasting results indicated that T. aestivum semolina gave the lowest onset gelatinization temperature (66.9°C but the highest peak viscosity (1.053 BU. Starch release was maximum in Comb1 (53.45% when compared with control (44.9% as also proved by microstructure studies. Firmness was seen to be slightly high in Comb3 (2.430 N when compared with control (2.304 N, and sensory evaluations were also in the acceptable range for the same. The present study concludes that Comb3 comprising 50% T. durum semolina and 50% T. aestivum refined wheat flour with additives would be optimal alternate for 100% T. durum semolina for production of financially viable pasta.

  9. Improving the accuracy of a dual-comb interferometer by suppressing the relative linewidth

    Science.gov (United States)

    Zhu, Zebin; Xu, Guangyao; Ni, Kai; Zhou, Qian; Wu, Guanhao

    2018-04-01

    We present a compact system of synchronization for two fiber-based optical frequency comb lasers. We use a free-running continuous wave laser as an intermediary to obtain the relative noise of two combs and employ an intra-cavity electro-optic modulator (EOM) to achieve active phase feedback for fast synchronization. The EOM bandwidth is 150 kHz and the relative linewidth is suppressed markedly from 300 kHz to sub-hertz values. The relative effective timing jitter of the two pulse trains is also decreased from 680 fs to 25 fs. The proposed method shows promise for developing a high-performance, low-cost, fiber-based dual-comb interferometer for ranging or spectroscopy.

  10. Perovskites in the comb roof base of hornets: their possible function.

    Science.gov (United States)

    Ishay, J S; Joseph, Z; Galushko, D; Ermakov, N; Bergman, D J; Barkay, Z; Stokroos, I; van der Want, J

    2005-04-01

    On the ceiling of the Oriental hornet comb cell, there are mineral granules of polycrystalline material known to belong to the group of perovskites. In a comb cell intended to house a worker hornet, the roof base usually carries one or several such perovskite granules containing titanium (Ti), whereas in the roof base of a cell housing a developing queen, there are usually several granules containing a high percentage of silicon (Si), aluminum (Al), calcium (Ca), and iron (Fe), but very little if any Ti. In worker comb cells, Ti usually appears as ilmenite (FeTiO3). Besides documenting the above-mentioned facts, this report discusses possible reasons for the appearance of ilmenite crystals in worker cells only and not in queen cells. (c) 2005 Wiley-Liss, Inc.

  11. Dual-comb spectroscopy of molecular electronic transitions in condensed phases

    Science.gov (United States)

    Cho, Byungmoon; Yoon, Tai Hyun; Cho, Minhaeng

    2018-03-01

    Dual-comb spectroscopy (DCS) utilizes two phase-locked optical frequency combs to allow scanless acquisition of spectra using only a single point detector. Although recent DCS measurements demonstrate rapid acquisition of absolutely calibrated spectral lines with unprecedented precision and accuracy, complex phase-locking schemes and multiple coherent averaging present significant challenges for widespread adoption of DCS. Here, we demonstrate Global Positioning System (GPS) disciplined DCS of a molecular electronic transition in solution at around 800 nm, where the absorption spectrum is recovered by using a single time-domain interferogram. We anticipate that this simplified dual-comb technique with absolute time interval measurement and ultrabroad bandwidth will allow adoption of DCS to tackle molecular dynamics investigation through its implementation in time-resolved nonlinear spectroscopic studies and coherent multidimensional spectroscopy of coupled chromophore systems.

  12. Generation and control of optical frequency combs using cavity electromagnetically induced transparency

    Science.gov (United States)

    Li, Jiahua; Qu, Ye; Yu, Rong; Wu, Ying

    2018-02-01

    We explore theoretically the generation and all-optical control of optical frequency combs (OFCs) in photon transmission based on a combination of single-atom-cavity quantum electrodynamics (CQED) and electromagnetically induced transparency (EIT). Here an external control field is used to form the cavity dark mode of the CQED system. When the strengths of the applied EIT control field are appropriately tuned, enhanced comb generation can be achieved. We discuss the properties of the dark mode and clearly show that the formation of the dark mode enables the efficient generation of OFCs. In our approach, the comb spacing is determined by the beating frequency between the driving pump and seed lasers. Our demonstrated theory may pave the way towards all-optical coherent control of OFCs using a CQED architecture.

  13. A Novel Comb-Pilot Transform Domain Frequency Diversity Channel Estimation for OFDM System

    Directory of Open Access Journals (Sweden)

    L. Liu

    2009-12-01

    Full Text Available Due to implementation complexity, the transform domain channel estimation based on training symbols or comb-type pilots has been paid more attention because of its efficient algorithm FFT/IFFT. However, in a comb-type OFDM system, the length of the channel impulse response is much smaller than the pilot number. In this case, the comb-pilot transform domain channel estimation only works as interpolation like the Least Squares (LS algorithm, but loses the noise suppression function. In this paper, we propose a novel frequency diversity channel estimation method via grouped pilots combining. With this estimator, not only the channel frequency response on non-pilot subcarriers can be interpolated, but also the noise can be better suppressed. Moreover, it does not need prior statistical characteristics of the wireless channel.

  14. A stabilized optical frequency comb based on an Er-doped fiber femtosecond laser

    Science.gov (United States)

    Xia, Chuanqing; Wu, Tengfei; Zhao, Chunbo; Xing, Shuai

    2018-03-01

    An optical frequency comb based on a 250 MHz home-made Er-doped fiber femtosecond laser is presented in this paper. The Er-doped fiber laser has a ring cavity and operates mode-locked in femtosecond regime with the technique of nonlinear polarization rotation. The pulse duration is 118 fs and the spectral width is 30 nm. A part of the femtosecond laser is amplified in Er-doped fiber amplifier before propagating through a piece of highly nonlinear fiber for expanding the spectrum. The carrier-envelope offset frequency of the comb which has a signal-to-noise ratio more than 35 dB is extracted by means of f-2f beating. It demonstrates that both carrier-envelope offset frequency and repetition frequency keep phase locked to a Rubidium atomic clock simultaneously for 2 hours. The frequency stabilized fiber combs will be increasingly applied in optical metrology, attosecond pulse generation, and absolute distance measurement.

  15. Low threshold frequency comb generation in AlGaAs-on-insulator microresonator in the normal dispersion regime

    DEFF Research Database (Denmark)

    Kamel, Ayman Nassar; Pu, Minhao; Yvind, Kresten

    2017-01-01

    We present milli-Watt threshold frequency comb generation in AlGaAs-on-insulator integrated microresonators exhibiting normal GVD by employing the effects of mode interaction.......We present milli-Watt threshold frequency comb generation in AlGaAs-on-insulator integrated microresonators exhibiting normal GVD by employing the effects of mode interaction....

  16. Phenotypic characteristics of upright and pendulous comb among chicken breeds and association with growth rate and egg production.

    Science.gov (United States)

    Wan, Yi; Wang, Zhicheng; Guo, Xing; Ma, Chendong; Fang, Qi; Geng, Zhaoyu; Chen, Xingyong; Jiang, Runshen

    2018-01-01

    Upright and pendulous combs commonly exist in most single-comb chicken breeds. Here, the phenotypic characteristics of upright and pendulous combs in chickens and association with growth rate and egg production were analyzed. Phenotypic frequencies of upright and pendulous comb were investigated in five chicken breeds; the phenotypic frequencies of complete pendulous comb (CPC) and partial pendulous comb (PPC) ranged from 10.1% to 29.0% and 21.8% to 65.3%, respectively. CPC hens produced more eggs than PPC hens (P chickens have greater (P chickens. There was no significant difference in comb phenotypic frequency distribution between the offspring from UC(♂) × CPC(♀) and CPC(♂) × UC(♀); however, it differed (χ² = 45.12, P < 0.01) between offspring from UC(♂) × UC(♀) and CPC(♂) × CPC(♀). These results suggested that the comb phenotype does not appear to be Z-linked; the effective loci influencing the trait could be estimated in a further study. © 2017 Japanese Society of Animal Science.

  17. Bacterial communities in termite fungus combs are comprised of consistent gut deposits and contributions from the environment

    DEFF Research Database (Denmark)

    Otani, Saria; Hansen, Lars Hestbjerg; Sørensen, Søren J

    2016-01-01

    , Actinobacteria, and Candidate division TM7 jointly accounting for 92 % of the reads. Analyses of gut microbiotas from 25 of the 33 colonies showed that dominant fungus comb taxa originate from the termite gut. While gut communities were consistent between 2011 and 2013, comb community compositions shifted over...

  18. Sex ratios

    OpenAIRE

    West, Stuart A; Reece, S E; Sheldon, Ben C

    2002-01-01

    Sex ratio theory attempts to explain variation at all levels (species, population, individual, brood) in the proportion of offspring that are male (the sex ratio). In many cases this work has been extremely successful, providing qualitative and even quantitative explanations of sex ratio variation. However, this is not always the situation, and one of the greatest remaining problems is explaining broad taxonomic patterns. Specifically, why do different organisms show so ...

  19. Frequency-comb-assisted broadband precision spectroscopy with cascaded diode lasers

    DEFF Research Database (Denmark)

    Liu, Junqiu; Brasch, Victor; Pfeiffer, Martin H. P.

    2016-01-01

    Frequency-comb-assisted diode laser spectroscopy, employing both the accuracy of an optical frequency comb and the broad wavelength tuning range of a tunable diode laser, has been widely used in many applications. In this Letter, we present a novel method using cascaded frequency agile diode lasers......, which allows us to extend the measurement bandwidth to 37.4 THz (1355-1630 nm) at megahertz resolution with scanning speeds above 1 THz/s. It is demonstrated as a useful tool to characterize a broadband spectrum for molecular spectroscopy, and in particular it enables us to characterize the dispersion...

  20. Numerical investigation into the injection-locking phenomena of gain switched lasers for optical frequency comb generation

    International Nuclear Information System (INIS)

    Ó Dúill, Sean P.; Anandarajah, Prince M.; Zhou, Rui; Barry, Liam P.

    2015-01-01

    We present detailed numerical simulations of the laser dynamics that describe optical frequency comb formation by injection-locking a gain-switched laser. The typical rate equations for semiconductor lasers including stochastic carrier recombination and spontaneous emission suffice to show the injection-locking behavior of gain switched lasers, and we show how the optical frequency comb evolves starting from the free-running state, right through the final injection-locked state. Unlike the locking of continuous wave lasers, we show that the locking range for gain switched lasers is considerably greater because injection locking can be achieved by injecting at frequencies close to one of the comb lines. The quality of the comb lines is formally assessed by calculating the frequency modulation (FM)-noise spectral density and we show that under injection-locking conditions the FM-noise spectral density of the comb lines tend to that of the maser laser

  1. Numerical investigation into the injection-locking phenomena of gain switched lasers for optical frequency comb generation

    Energy Technology Data Exchange (ETDEWEB)

    Ó Dúill, Sean P., E-mail: sean.oduill@dcu.ie; Anandarajah, Prince M.; Zhou, Rui; Barry, Liam P. [The RINCE Institute, Dublin City University, Glasnevin, Dublin 9 (Ireland)

    2015-05-25

    We present detailed numerical simulations of the laser dynamics that describe optical frequency comb formation by injection-locking a gain-switched laser. The typical rate equations for semiconductor lasers including stochastic carrier recombination and spontaneous emission suffice to show the injection-locking behavior of gain switched lasers, and we show how the optical frequency comb evolves starting from the free-running state, right through the final injection-locked state. Unlike the locking of continuous wave lasers, we show that the locking range for gain switched lasers is considerably greater because injection locking can be achieved by injecting at frequencies close to one of the comb lines. The quality of the comb lines is formally assessed by calculating the frequency modulation (FM)-noise spectral density and we show that under injection-locking conditions the FM-noise spectral density of the comb lines tend to that of the maser laser.

  2. Real-time dual-comb spectroscopy with a free-running bidirectionally mode-locked fiber laser

    Science.gov (United States)

    Mehravar, S.; Norwood, R. A.; Peyghambarian, N.; Kieu, K.

    2016-06-01

    Dual-comb technique has enabled exciting applications in high resolution spectroscopy, precision distance measurements, and 3D imaging. Major advantages over traditional methods can be achieved with dual-comb technique. For example, dual-comb spectroscopy provides orders of magnitude improvement in acquisition speed over standard Fourier-transform spectroscopy while still preserving the high resolution capability. Wider adoption of the technique has, however, been hindered by the need for complex and expensive ultrafast laser systems. Here, we present a simple and robust dual-comb system that employs a free-running bidirectionally mode-locked fiber laser operating at telecommunication wavelength. Two femtosecond frequency combs (with a small difference in repetition rates) are generated from a single laser cavity to ensure mutual coherent properties and common noise cancellation. As the result, we have achieved real-time absorption spectroscopy measurements without the need for complex servo locking with accurate frequency referencing, and relatively high signal-to-noise ratio.

  3. Creating Sex

    DEFF Research Database (Denmark)

    Cahana, Jonathan

    2016-01-01

    Thomas Laqueur’s influential yet controversial study Making Sex has, in many ways, revolutionized our understanding of sexuality in antiquity. Yet, most of Laqueur’s critics and supporters stressed the one-sex body, while the crux of his argument is the primacy of gender. Moreover, a systematic...

  4. Sex determination

    Indian Academy of Sciences (India)

    The sex-determining system differs considerably among organisms. Even among insect species, the genetic system for sex-determination is highly diversified. In Drosophila melanogaster, somatic sexual differentiation is regulated by a well characterized genetic hierarchy X : A > Sxl > tra/tra2 > dsx and fru. This cascade ...

  5. Multifrequency sources of quantum correlated photon pairs on-chip: a path toward integrated Quantum Frequency Combs

    Directory of Open Access Journals (Sweden)

    Caspani Lucia

    2016-06-01

    Full Text Available Recent developments in quantum photonics have initiated the process of bringing photonic-quantumbased systems out-of-the-lab and into real-world applications. As an example, devices to enable the exchange of a cryptographic key secured by the laws of quantum mechanics are already commercially available. In order to further boost this process, the next step is to transfer the results achieved by means of bulky and expensive setups into miniaturized and affordable devices. Integrated quantum photonics is exactly addressing this issue. In this paper, we briefly review the most recent advancements in the generation of quantum states of light on-chip. In particular, we focus on optical microcavities, as they can offer a solution to the problem of low efficiency that is characteristic of the materials typically used in integrated platforms. In addition, we show that specifically designed microcavities can also offer further advantages, such as compatibility with telecom standards (for exploiting existing fibre networks and quantum memories (necessary to extend the communication distance, as well as giving a longitudinal multimode character for larger information transfer and processing. This last property (i.e., the increased dimensionality of the photon quantum state is achieved through the ability to generate multiple photon pairs on a frequency comb, corresponding to the microcavity resonances. Further achievements include the possibility of fully exploiting the polarization degree of freedom, even for integrated devices. These results pave the way for the generation of integrated quantum frequency combs that, in turn, may find important applications toward the realization of a compact quantum-computing platform.

  6. Comb-shaped single ion conductors based on polyacrylate ethers and lithium alkyl sulfonate

    International Nuclear Information System (INIS)

    Sun Xiaoguang; Hou Jun; Kerr, John B.

    2005-01-01

    Comb-shaped single ion conductors have been synthesized by (1) sulfonation of small molecule chloroethyleneglycols, which, after ion exchange to the Li + salt were then converted to the acrylate by reaction with acryloyl chloride and copolymerized with polyethylene glycol monomethyl ether acrylate (Mn = 454, n = 8) (PAE 8 -co-E 3 SO 3 Li); (2) sulfonation of chloride end groups grafted on to prepolymers of polyacrylate ethers (PAE 8 -g-E n SO 3 Li, n = 2, 3). The highest conductivity at 25 deg. C of 2.0 x 10 -7 S cm -1 was obtained for the PAE 8 -co-E 3 SO 3 Li with a salt concentration of EO/Li = 40. The conductivity of PAE 8 -g-E 3 SO 3 Li is lower than that of PAE 8 -co-E 3 SO 3 Li at similar salt concentrations, which is related to the incomplete sulfonation of the grafted polymer that leads to a lower concentration of Li + . The addition of 50 wt.% of plasticizer, PC/EMC (1/1, v/v), to PAE 8 -g-E 2 SO 3 Li increases the ambient conductivity by three orders of magnitude, which is due to the increased ion mobility in a micro-liquid environment and an increase concentration of free ions as a result of the higher dielectric constant of the solvent. A symmetrical Li/Li cell with an electrolyte membrane consisting of 75 wt.% PC/EMC (1/1, v/v) was cycled at a current density of 100 μA cm -2 at 85 deg. C. The cycling profile showed no concentration polarization after a break-in period during the first few cycles, which was apparently due to reaction of the solvent at the lithium metal surface that reacted with lithium metal to form a stable SEI layer

  7. Diagnostic features of quantitative comb-push shear elastography for breast lesion differentiation.

    Science.gov (United States)

    Bayat, Mahdi; Denis, Max; Gregory, Adriana; Mehrmohammadi, Mohammad; Kumar, Viksit; Meixner, Duane; Fazzio, Robert T; Fatemi, Mostafa; Alizad, Azra

    2017-01-01

    Lesion stiffness measured by shear wave elastography has shown to effectively separate benign from malignant breast masses. The aim of this study was to evaluate different aspects of Comb-push Ultrasound Shear Elastography (CUSE) performance in differentiating breast masses. With written signed informed consent, this HIPAA- compliant, IRB approved prospective study included patients from April 2014 through August 2016 with breast masses identified on conventional imaging. Data from 223 patients (19-85 years, mean 59.93±14.96 years) with 227 suspicious breast masses identifiable by ultrasound (mean size 1.83±2.45cm) were analyzed. CUSE was performed on all patients. Three regions of interest (ROI), 3 mm in diameter each, were selected inside the lesion on the B-mode ultrasound which also appeared in the corresponding shear wave map. Lesion elasticity values were measured in terms of the Young's modulus. In correlation to pathology results, statistical analyses were performed. Pathology revealed 108 lesions as malignant and 115 lesions as benign. Additionally, 4 lesions (BI-RADS 2 and 3) were considered benign and were not biopsied. Average lesion stiffness measured by CUSE resulted in 84.26% sensitivity (91 of 108), 89.92% specificity (107 of 119), 85.6% positive predictive value, 89% negative predictive value and 0.91 area under the curve (P 0.21). CUSE was able to distinguish between benign and malignant breast masses with high sensitivity and specificity. Continuity of stiffness maps allowed for choosing multiple quantification ROIs which covered large areas of lesions and resulted in similar diagnostic performance based on average and maximum elasticity. The overall results of this study, highlights the clinical value of CUSE in differentiation of breast masses based on their stiffness.

  8. Diagnostic features of quantitative comb-push shear elastography for breast lesion differentiation.

    Directory of Open Access Journals (Sweden)

    Mahdi Bayat

    Full Text Available Lesion stiffness measured by shear wave elastography has shown to effectively separate benign from malignant breast masses. The aim of this study was to evaluate different aspects of Comb-push Ultrasound Shear Elastography (CUSE performance in differentiating breast masses.With written signed informed consent, this HIPAA- compliant, IRB approved prospective study included patients from April 2014 through August 2016 with breast masses identified on conventional imaging. Data from 223 patients (19-85 years, mean 59.93±14.96 years with 227 suspicious breast masses identifiable by ultrasound (mean size 1.83±2.45cm were analyzed. CUSE was performed on all patients. Three regions of interest (ROI, 3 mm in diameter each, were selected inside the lesion on the B-mode ultrasound which also appeared in the corresponding shear wave map. Lesion elasticity values were measured in terms of the Young's modulus. In correlation to pathology results, statistical analyses were performed.Pathology revealed 108 lesions as malignant and 115 lesions as benign. Additionally, 4 lesions (BI-RADS 2 and 3 were considered benign and were not biopsied. Average lesion stiffness measured by CUSE resulted in 84.26% sensitivity (91 of 108, 89.92% specificity (107 of 119, 85.6% positive predictive value, 89% negative predictive value and 0.91 area under the curve (P 0.21.CUSE was able to distinguish between benign and malignant breast masses with high sensitivity and specificity. Continuity of stiffness maps allowed for choosing multiple quantification ROIs which covered large areas of lesions and resulted in similar diagnostic performance based on average and maximum elasticity. The overall results of this study, highlights the clinical value of CUSE in differentiation of breast masses based on their stiffness.

  9. Comb polymer architecture and particle size effects on the behavior of biphasic nanoparticle inks for direct-write assembly

    Science.gov (United States)

    Yoshikawa, Jun

    Biphasic nanoparticle mixtures composed of attractive and repulsive colloidal species enable the direct-write assembly of 3D structures with much finer features than those produced by pure colloidal gels. These mixtures rely on the use of comb polymer dispersants to render one particle population stable, while the other population is attractive. In this thesis, we systematically investigate the effects of comb polymer architecture and particle size ratio on the behavior of biphasic nanoparticle inks with the overarching aim of further advancing the direct-write assembly of 3D colloidal structures. We first investigated the effects of both pure polyelectrolytes, poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), and comb polymer dispersants composed of a PMAA backbone with methoxy-poly(ethylene oxide) (mPEO) teeth of varying molecular weights on the stability of barium titanate (BaTiO 3) suspensions. While each dispersant imparts stability to BaTiO 3 nanoparticles at low ionic strength (teeth (MWteeth = 2000) provides stability at higher ionic strengths over a broad range of particle sizes and counterion valencies. These results provide guidelines for tailoring the molecular architecture and functionality of comb polymer dispersants for optimal stabilization of the repulsive particle population within the biphasic inks. Next, particle size effects on the rheological properties of biphasic nanoparticle suspensions are studied. Shear elastic modulus, shear yield stress, and compressive yield stress are measured for mixtures of varying total volume fraction, attractive-to-repulsive volume fraction, and particle size ratio between attractive and repulsive species. Our observations indicate that the repulsive particles hinder the formation of the attractive gel network. The time required for shear elastic modulus to approach a steady-state value increases with the fraction of repulsive species. Furthermore, this behavior becomes more significant with increasing

  10. Transmission comb of a distributed Bragg reflector with two surface dielectric gratings

    KAUST Repository

    Zhao, Xiaobo; Zhang, Yongyou; Zhang, Qingyun; Zou, Bingsuo; Schwingenschlö gl, Udo

    2016-01-01

    The transmission behaviour of a distributed Bragg reector (DBR) with surface dielectric gratings on top and bottom is studied. The transmission shows a comb-like spectrum in the DBR band gap, which is explained in the Fano picture. The number

  11. Synthesis of ZnO comb-like nanostructures for high sensitivity H2S ...

    Indian Academy of Sciences (India)

    2017-09-15

    Sep 15, 2017 ... H2S gas sensor; ZnO comb-like nanostructures; chemical vapour deposition; vapour–solid growth; ... tube at a flow rate of 15 sccm, when the central temperature .... behaviour, in this case, under low input power implies ohmic.

  12. Optical Comb Generation for Streak Camera Calibration for Inertial Confinement Fusion Experiments

    International Nuclear Information System (INIS)

    Ronald Justin; Terence Davies; Frans Janson; Bruce Marshall; Perry Bell; Daniel Kalantar; Joseph Kimbrough; Stephen Vernon; Oliver Sweningsen

    2008-01-01

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is coming on-line to support physics experimentation for the U.S. Department of Energy (DOE) programs in Inertial Confinement Fusion (ICF) and Stockpile Stewardship (SS). Optical streak cameras are an integral part of the experimental diagnostics instrumentation at NIF. To accurately reduce streak camera data a highly accurate temporal calibration is required. This article describes a technique for simultaneously generating a precise +/- 2 ps optical marker pulse (fiducial reference) and trains of precisely timed, short-duration optical pulses (so-called 'comb' pulse trains) that are suitable for the timing calibrations. These optical pulse generators are used with the LLNL optical streak cameras. They are small, portable light sources that, in the comb mode, produce a series of temporally short, uniformly spaced optical pulses, using a laser diode source. Comb generators have been produced with pulse-train repetition rates up to 10 GHz at 780 nm, and somewhat lower frequencies at 664 nm. Individual pulses can be as short as 25-ps FWHM. Signal output is via a fiber-optic connector on the front panel of the generator box. The optical signal is transported from comb generator to streak camera through multi-mode, graded-index optical fiber

  13. Versatile mid-infrared frequency-comb referenced sub-Doppler spectrometer

    Directory of Open Access Journals (Sweden)

    A. Gambetta

    2018-04-01

    Full Text Available We present a mid-IR high-precision spectrometer capable of performing accurate Doppler-free measurements with absolute calibration of the optical axis and high signal-to-noise ratio. The system is based on a widely tunable mid-IR offset-free frequency comb and a Quantum-Cascade-Laser (QCL. The QCL emission frequency is offset locked to one of the comb teeth to provide absolute-frequency calibration, spectral-narrowing, and accurate fine frequency tuning. Both the comb repetition frequency and QCL-comb offset frequency can be modulated to provide, respectively, slow- and fast-frequency-calibrated scanning capabilities. The characterisation of the spectrometer is demonstrated by recording sub-Doppler saturated absorption features of the CHF3 molecule at around 8.6 μm with a maximum signal-to-noise ratio of ∼7 × 103 in 10 s integration time, frequency-resolution of 160 kHz, and accuracy of less than 10 kHz.

  14. Wooden combs from the Roman fort at Vechten: the bodily appearance of soldiers

    NARCIS (Netherlands)

    Derks, A.M.J.; Vos, W.K.

    2010-01-01

    Abstract Excavations in the late 19th century and surveys carried out in the 1970s have produced 12 boxwood combs from the Roman fort at Vechten (NL). They are to be considered waste material that was dumped in the river Rhine which in the Roman period ran just north of the camp. In this article,

  15. Osmotic pressure and virial coefficients of star and comb polymer solutions: dissipative particle dynamics.

    Science.gov (United States)

    Wang, Tzu-Yu; Fang, Che-Ming; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2009-03-28

    The effects of macromolecular architecture on the osmotic pressure pi and virial coefficients (B(2) and B(3)) of star and comb polymers in good solvents are studied by dissipative particle dynamics simulations for both dilute and semiconcentrated regimes. The dependence of the osmotic pressure on polymer concentration is directly calculated by considering two reservoirs separated by a semipermeable, fictitious membrane. Our simulation results show that the ratios A(n+1) identical with B(n+1)/R(g)(3n) are essentially constant and A(2) and A(3) are arm number (f) dependent, where R(g) is zero-density radius of gyration. The value of dimensionless virial ratio g = A(3)/A(2)(2) increases with arm number of stars whereas it is essentially arm number independent for comb polymers. In semiconcentrated regime the scaling relation between osmotic pressure and volume fraction, pi proportional to phi(lambda), still holds for both star and comb polymers. For comb polymers, the exponent lambda is close to lambda(*) (approximately = 2.73 for linear chains) and is independent of the arm number. However, for star polymers, the exponent lambda deviates from lambda(*) and actually grows with increasing the arm number. This may be attributed to the significant ternary interactions near the star core in the many-arm systems.

  16. Versatile mid-infrared frequency-comb referenced sub-Doppler spectrometer

    Science.gov (United States)

    Gambetta, A.; Vicentini, E.; Coluccelli, N.; Wang, Y.; Fernandez, T. T.; Maddaloni, P.; De Natale, P.; Castrillo, A.; Gianfrani, L.; Laporta, P.; Galzerano, G.

    2018-04-01

    We present a mid-IR high-precision spectrometer capable of performing accurate Doppler-free measurements with absolute calibration of the optical axis and high signal-to-noise ratio. The system is based on a widely tunable mid-IR offset-free frequency comb and a Quantum-Cascade-Laser (QCL). The QCL emission frequency is offset locked to one of the comb teeth to provide absolute-frequency calibration, spectral-narrowing, and accurate fine frequency tuning. Both the comb repetition frequency and QCL-comb offset frequency can be modulated to provide, respectively, slow- and fast-frequency-calibrated scanning capabilities. The characterisation of the spectrometer is demonstrated by recording sub-Doppler saturated absorption features of the CHF3 molecule at around 8.6 μm with a maximum signal-to-noise ratio of ˜7 × 103 in 10 s integration time, frequency-resolution of 160 kHz, and accuracy of less than 10 kHz.

  17. Frequency Combs in a Lumped-Element Josephson-Junction Circuit

    Science.gov (United States)

    Khan, Saeed; Türeci, Hakan E.

    2018-04-01

    We investigate the dynamics of a microwave-driven Josephson junction capacitively coupled to a lumped-element L C oscillator. In the regime of driving where the Josephson junction can be approximated as a Kerr oscillator, this minimal nonlinear system has been previously shown to exhibit a bistability in phase and amplitude. In the present study, we characterize the full phase diagram and show that besides a parameter regime exhibiting bistability, there is also a regime of self-oscillations characterized by a frequency comb in its spectrum. We discuss the mechanism of comb generation which appears to be different from those studied in microcavity frequency combs and mode-locked lasers. We then address the fate of the comblike spectrum in the regime of strong quantum fluctuations, reached when nonlinearity becomes the dominant scale with respect to dissipation. We find that the nonlinearity responsible for the emergence of the frequency combs also leads to its dephasing, leading to broadening and ultimate disappearance of sharp spectral peaks. Our study explores the fundamental question of the impact of quantum fluctuations for quantum systems which do not possess a stable fixed point in the classical limit.

  18. A decade of astrocombs: recent advances in frequency combs for astronomy.

    Science.gov (United States)

    McCracken, Richard A; Charsley, Jake M; Reid, Derryck T

    2017-06-26

    A new regime of precision radial-velocity measurements in the search for Earth-like exoplanets is being facilitated by high-resolution spectrographs calibrated by laser frequency combs. Here we review recent advances in the development of astrocomb technology, and discuss the state of the field going forward.

  19. Power, Prayers, and Protection: Comb Ridge as a Case Study in Navajo Thought

    Science.gov (United States)

    McPherson, Robert S.

    2010-01-01

    Beginning in 2005, a five-year survey of cultural resources began to unfold in southeastern Utah along a prominent sandstone rock formation known as Comb Ridge. This visually dramatic monocline stretches a considerable distance from the southwestern corner of Blue Mountain (Abajos) in Utah to Kayenta, Arizona, approximately one hundred miles to…

  20. Wideband optical vector network analyzer based on optical single-sideband modulation and optical frequency comb.

    Science.gov (United States)

    Xue, Min; Pan, Shilong; He, Chao; Guo, Ronghui; Zhao, Yongjiu

    2013-11-15

    A novel approach to increase the measurement range of the optical vector network analyzer (OVNA) based on optical single-sideband (OSSB) modulation is proposed and experimentally demonstrated. In the proposed system, each comb line in an optical frequency comb (OFC) is selected by an optical filter and used as the optical carrier for the OSSB-based OVNA. The frequency responses of an optical device-under-test (ODUT) are thus measured channel by channel. Because the comb lines in the OFC have fixed frequency spacing, by fitting the responses measured in all channels together, the magnitude and phase responses of the ODUT can be accurately achieved in a large range. A proof-of-concept experiment is performed. A measurement range of 105 GHz and a resolution of 1 MHz is achieved when a five-comb-line OFC with a frequency spacing of 20 GHz is applied to measure the magnitude and phase responses of a fiber Bragg grating.

  1. Influence of deep RIE tolerances on comb-drive actuator performance

    International Nuclear Information System (INIS)

    Chen, Bangtao; Miao, Jianmin

    2007-01-01

    This paper analyses the various etching tolerances and profiles of comb-drive microstructures by using deep reactive ion etching (RIE) and studies their influence on the actuator's performance. The comb-drive actuators studied in this paper are fabricated with the silicon-on-glass (SOG) wafer process using deep RIE and wafer bonding, which present very high-aspect-ratio and high-strength microstructures. However, the deep RIE process generates some tolerances and varies the dimension and profile of comb fingers and flexures due to the process limitations. We have analysed the different etching tolerances and studied their influence on the actuator's performance, in terms of the electrostatic force, flexure stiffness, actuator's displacement, air damping and quality factor of the actuator. The analysis shows that the comb fingers with a positive slope profile generated a larger electrostatic force, and the flexures with a negative profile induced the loss of the actuator's stiffness. The combination of these two profiles leads to a great increase in the actuator's displacement and decrease in the quality factor. The measured results of the SOG fabricated actuators have demonstrated the influence of deep RIE tolerance on the actuator's performance

  2. Air Damping in a Fan-Shaped Rotational Resonator with Comb Electrodes

    Science.gov (United States)

    Uchida, Yuki; Sugano, Koji; Tsuchiya, Toshiyuki; Tabata, Osamu; Ikehara, Tsuyoshi

    We theoretically and experimentally evaluated the damping effect in a rotational resonator with a comb-drive actuator and sensor. The resonator was fabricated from an SOI wafer and has a fan-shaped mass. The underlying substrate was removed using back side deep reactive ion etching. One set of comb electrodes was attached to each side of the mass: one for electrostatic driving and the other for capacitive detection. In our theoretical analysis, the dynamics of the resonator were simplified so that they could be represented by a lumped system. In this lumped system, the damping coefficient was estimated by assuming the damping to be slide film damping and the air flow to be a Stokes flow. The phase shift due to the slide film damping of thick air layers was included in the lumped system. In the experimental evaluation, one side of the rotational combs was removed step-by-step and a half of the mass using a laser trimming tool so that the individual damping effects caused by the comb electrodes and mass could be determined quantitatively. We compared the experimental results with the results of the theoretical analysis and found that the difference in the damping coefficients between the experimental results and results of the theoretical analysis was less than 40%.

  3. Look closer: Time sequence photography of Roosters Comb in the Sheep Creek Range, Nevada

    Science.gov (United States)

    The importance of understanding natural landscape changes is key in properly determining rangeland ecology. Time sequence photography allows a snapshot of a landscape to be documented and enables the ability to compare natural changes overtime. Photographs of Roosters Comb were taken from the same v...

  4. Comb-like thermoresponsive polymeric materials : Synthesis and effect of macromolecular structure on solution properties

    NARCIS (Netherlands)

    Wever, D. A. Z.; Riemsma, E.; Picchioni, F.; Broekhuis, A. A.

    2013-01-01

    A series of comb-like block and random copolymers based on acrylamide (AM) and N-isopropylacrylamide (NIPAM) have been prepared by atom transfer radical polymerization (ATRP). The number of side-arms, the length of the AM and NIPAM blocks as well as the distribution of the two monomers (block or

  5. Microencapsulated Comb-Like Polymeric Solid-Solid Phase Change Materials via In-Situ Polymerization

    Directory of Open Access Journals (Sweden)

    Wei Li

    2018-02-01

    Full Text Available To enhance the thermal stability and permeability resistance, a comb-like polymer with crystallizable side chains was fabricated as solid-solid phase change materials (PCMs inside the cores of microcapsules and nanocapsules prepared via in-situ polymerization. In this study, the effects on the surface morphology and microstructure of micro/nanocapsules caused by microencapsulating different types of core materials (i.e., n-hexadecane, ethyl hexadecanoate, hexadecyl acrylate and poly(hexadecyl acrylate were systematically studied via field emission scanning electron microscope (FE-SEM and transmission electron microscope (TEM. The confined crystallization behavior of comb-like polymer PCMs cores was investigated via differential scanning calorimeter (DSC. Comparing with low molecular organic PCMs cores, the thermal stability of PCMs microencapsulated comb-like polymer enhanced significantly, and the permeability resistance improved obviously as well. Based on these resultant analysis, the microencapsulated comb-like polymeric PCMs with excellent thermal stability and permeability resistance showed promising foreground in the field of organic solution spun, melt processing and organic coating.

  6. Atomic and molecular spectroscopy with optical-frequency-comb-referenced IR coherent sources

    International Nuclear Information System (INIS)

    Cancio, P.; Bartalini, S.; De Rosa, M.; Giusfredi, G.; Mazzotti, D.; Maddaloni, P.; Vitiello, M. S.; De Natale, P.

    2013-01-01

    We provide a review of progress in the development of metrological-grade measurements in atomic and molecular systems through the extension, in the mid-infrared and far-infrared range, of optical frequency combs (OFCs) and the introduction of new techniques and highly coherent sources. (authors)

  7. Centralized optical-frequency-comb-based RF carrier generator for DWDM fiber-wireless access systems

    DEFF Research Database (Denmark)

    Pang, Xiaodan; Beltran, Marta; Sanchez, Jose

    2014-01-01

    In this paper, we report on a gigabit capacity fiber-wireless system that enables smooth integration between high-speed wireless networks and dense wavelength-division-multiplexing (DWDM) access networks. By employing a centralized optical frequency comb, both the wireline and the wireless services...

  8. Microphase Separation within a Comb Copolymer with Attractive Side Chains : A Computer Simulation Study

    NARCIS (Netherlands)

    Vasilevskaya, V.V.; Klochkov, A.A.; Khalatur, P.G.; Khokhlov, A.R.; Brinke, G. ten

    2001-01-01

    Computer simulation modelling of a flexible comb copolymer with attractive interactions between the monomer units of the side chains is performed. The conditions for the coil-globule transition, induced by the increase of attractive interaction, ε, between side chain monomer units, are analysed for

  9. All solid state mid-infrared dual-comb spectroscopy platform based on QCL technology

    Science.gov (United States)

    Hugi, Andreas; Geiser, Markus; Villares, Gustavo; Cappelli, Francesco; Blaser, Stephane; Faist, Jérôme

    2015-01-01

    We develop a spectroscopy platform for industrial applications based on semiconductor quantum cascade laser (QCL) frequency combs. The platform's key features will be an unmatched combination of bandwidth of 100 cm-1, resolution of 100 kHz, speed of ten to hundreds of μs as well as size and robustness, opening doors to beforehand unreachable markets. The sensor can be built extremely compact and robust since the laser source is an all-electrically pumped semiconductor optical frequency comb and no mechanical elements are required. However, the parallel acquisition of dual-comb spectrometers comes at the price of enormous data-rates. For system scalability, robustness and optical simplicity we use free-running QCL combs. Therefore no complicated optical locking mechanisms are required. To reach high signal-to-noise ratios, we develop an algorithm, which is based on combination of coherent and non-coherent averaging. This algorithm is specifically optimized for free-running and small footprint, therefore high-repetition rate, comb sources. As a consequence, our system generates data-rates of up to 3.2 GB/sec. These data-rates need to be reduced by several orders of magnitude in real-time in order to be useful for spectral fitting algorithms. We present the development of a data-treatment solution, which reaches a single-channel throughput of 22% using a standard laptop-computer. Using a state-of-the art desktop computer, the throughput is increased to 43%. This is combined with a data-acquisition board to a stand-alone data processing unit, allowing real-time industrial process observation and continuous averaging to achieve highest signal fidelity.

  10. Oral sex.

    Science.gov (United States)

    1996-04-05

    The Gay and Lesbian Medical Association urges HIV prevention specialists to regard male-to-male oral-genital sex as a low-risk activity and concentrate instead on the danger of unprotected anal intercourse. According to the association, the confusion and mixed messages surrounding oral sex are harming efforts to encourage gay men to make rational choices about truly risky behavior. The recommendations appear in the association's position paper issued March 19, 1996.

  11. Why Sex?

    DEFF Research Database (Denmark)

    Nielsen, Rasmus

    2006-01-01

    It is assumed that most organisms have sex because the resulting genetic recombination allows Darwinian selection to work better. It is now shown that in water fleas, recombination does lead to fewer deleterious mutations.......It is assumed that most organisms have sex because the resulting genetic recombination allows Darwinian selection to work better. It is now shown that in water fleas, recombination does lead to fewer deleterious mutations....

  12. Sex education in Portugal.

    Science.gov (United States)

    Frade, A; Vilar, D

    1991-05-01

    The article on sex education in Portugal covers background, the educational system, the clashes of the 1960's over sex education, the Committee for the Study of Sexuality and Education (CSSE), the policies, politics and social movements during the period 1974 - 1984, the discussions in Parliament, the 1988 Reform of the Educational System, the Family Planning Association (FPA) and sex education, and the future role of the FPA. It was not until the institution of the multiparity parliamentary system in 1974 that discussing social and political changes was possible, culminating in 1984 with new legislation on abortion, family planning, and sex education. School reform came in 1987/8 with the Ministry of Education primarily responsible for curricula. The 1960's brought with it the influence of the Catholic Church. Change came in the form of progressivism among Catholics who replaced dogma with dialogue and listening. Sex education was considered as preparation for marriage, but masturbation, contraception, and prostitution were also discussed. In addition, the founder of FPA chaired the CSSE in 1971 and opened up debate on sex issues and drafted a bill to establish co-education in Portuguese schools. The revolution of 1974 brought an end to censorship and brought forth a policy of developing family planning. Changed in the Family Code gave women greater equality. UNFPA supported teacher training in non-sexist education. With human reproduction included in the natural sciences, there was still no school sex education policy and contraception was only sometimes represented in the biology curriculum. The focus of FPA was on contraception and abortion. Finally in the 1980's, the first sex education programs were developed for out-of-school youth. Even though in the 1970's there were leftists groups promoting sex education, it took leftist parliamentary power to get legislation on sex education in the schools adopted. The Ministry of Education however was pressured by the

  13. High-power Yb-fiber comb based on pre-chirped-management self-similar amplification

    Science.gov (United States)

    Luo, Daping; Liu, Yang; Gu, Chenglin; Wang, Chao; Zhu, Zhiwei; Zhang, Wenchao; Deng, Zejiang; Zhou, Lian; Li, Wenxue; Zeng, Heping

    2018-02-01

    We report a fiber self-similar-amplification (SSA) comb system that delivers a 250-MHz, 109-W, 42-fs pulse train with a 10-dB spectral width of 85 nm at 1056 nm. A pair of grisms is employed to compensate the group velocity dispersion and third-order dispersion of pre-amplified pulses for facilitating a self-similar evolution and a self-phase modulation (SPM). Moreover, we analyze the stabilities and noise characteristics of both the locked carrier envelope phase and the repetition rate, verifying the stability of the generated high-power comb. The demonstration of the SSA comb at such high power proves the feasibility of the SPM-based low-noise ultrashort comb.

  14. Call for papers for special issue of Journal of Molecular Spectroscopy focusing on "Frequency-comb spectroscopy"

    Science.gov (United States)

    Foltynowicz, Aleksandra; Picqué, Nathalie; Ye, Jun

    2018-05-01

    Frequency combs are becoming enabling tools for many applications in science and technology, beyond the original purpose of frequency metrology of simple atoms. The precisely evenly spaced narrow lines of a laser frequency comb inspire intriguing approaches to molecular spectroscopy, designed and implemented by a growing community of scientists. Frequency-comb spectroscopy advances the frontiers of molecular physics across the entire electro-magnetic spectrum. Used as frequency rulers, frequency combs enable absolute frequency measurements and precise line shape studies of molecular transitions, for e.g. tests of fundamental physics and improved determination of fundamental constants. As light sources interrogating the molecular samples, they dramatically improve the resolution, precision, sensitivity and acquisition time of broad spectral-bandwidth spectroscopy and open up new opportunities and applications at the leading edge of molecular spectroscopy and sensing.

  15. Moral Pluralism and Sex Education

    Science.gov (United States)

    Corngold, Josh

    2013-01-01

    How should common schools in a liberal pluralist society approach sex education in the face of deep disagreement about sexual morality? Should they eschew sex education altogether? Should they narrow its focus to facts about biology, reproduction, and disease prevention? Should they, in addition to providing a broad palette of information about…

  16. High-resolution quantization based on soliton self-frequency shift and spectral compression in a bi-directional comb-fiber architecture

    Science.gov (United States)

    Zhang, Xuyan; Zhang, Zhiyao; Wang, Shubing; Liang, Dong; Li, Heping; Liu, Yong

    2018-03-01

    We propose and demonstrate an approach that can achieve high-resolution quantization by employing soliton self-frequency shift and spectral compression. Our approach is based on a bi-directional comb-fiber architecture which is composed of a Sagnac-loop-based mirror and a comb-like combination of N sections of interleaved single-mode fibers and high nonlinear fibers. The Sagnac-loop-based mirror placed at the terminal of a bus line reflects the optical pulses back to the bus line to achieve additional N-stage spectral compression, thus single-stage soliton self-frequency shift (SSFS) and (2 N - 1)-stage spectral compression are realized in the bi-directional scheme. The fiber length in the architecture is numerically optimized, and the proposed quantization scheme is evaluated by both simulation and experiment in the case of N = 2. In the experiment, a quantization resolution of 6.2 bits is obtained, which is 1.2-bit higher than that of its uni-directional counterpart.

  17. Synthesis and characterization of an exact comb polyisoprene with three branches having the middle branch twice the molecular weight of the other two identical external branches

    KAUST Repository

    Ratkanthwar, Kedar

    2013-01-01

    An exact comb polyisoprene (PI) with three branches, with the middle branch having twice the molecular weight of the two other identical external branches, was synthesized by using anionic polymerization high vacuum techniques and appropriate chlorosilane chemistry. The synthetic approach involves (a) the selective replacement of the two chlorines of 4-(dichloromethylsilyl) diphenylethylene (DCMSDPE, key molecule) with identical PI chains by titration with PILi, (b) the addition of sec-BuLi to the double bond of DPE followed by the polymerization of isoprene from the newly created anionic site to form a 3-arm living star PI, (c) the selective replacement of the two chlorines of trichloromethylsilane with 3-arm star PI to form an H-shape intermediate, and (d) the replacement of the remaining chlorine of trichloromethylsilane by linear PI chains with double the molecular weight. All intermediate and final products were characterized via size exclusion chromatography, temperature gradient interaction chromatography and 1H-NMR spectroscopy. As expected, due to the inability to control the exact stoichiometry of the linking reactants, the main product (exact comb PI) is contaminated by a few by-products, despite the fact that anionic polymerization is the most efficient way to produce well-defined polymers. © 2013 The Royal Society of Chemistry.

  18. Wavelength calibration with PMAS at 3.5 m Calar Alto Telescope using a tunable astro-comb

    Science.gov (United States)

    Chavez Boggio, J. M.; Fremberg, T.; Bodenmüller, D.; Sandin, C.; Zajnulina, M.; Kelz, A.; Giannone, D.; Rutowska, M.; Moralejo, B.; Roth, M. M.; Wysmolek, M.; Sayinc, H.

    2018-05-01

    On-sky tests conducted with an astro-comb using the Potsdam Multi-Aperture Spectrograph (PMAS) at the 3.5 m Calar Alto Telescope are reported. The proposed astro-comb approach is based on cascaded four-wave mixing between two lasers propagating through dispersion optimized nonlinear fibers. This approach allows for a line spacing that can be continuously tuned over a broad range (from tens of GHz to beyond 1 THz) making it suitable for calibration of low- medium- and high-resolution spectrographs. The astro-comb provides 300 calibration lines and his line-spacing is tracked with a wavemeter having 0.3 pm absolute accuracy. First, we assess the accuracy of Neon calibration by measuring the astro-comb lines with (Neon calibrated) PMAS. The results are compared with expected line positions from wavemeter measurement showing an offset of ∼5-20 pm (4%-16% of one resolution element). This might be the footprint of the accuracy limits from actual Neon calibration. Then, the astro-comb performance as a calibrator is assessed through measurements of the Ca triplet from stellar objects HD3765 and HD219538 as well as with the sky line spectrum, showing the advantage of the proposed astro-comb for wavelength calibration at any resolution.

  19. Transmission comb of a distributed Bragg reflector with two surface dielectric gratings

    KAUST Repository

    Zhao, Xiaobo

    2016-02-19

    The transmission behaviour of a distributed Bragg reector (DBR) with surface dielectric gratings on top and bottom is studied. The transmission shows a comb-like spectrum in the DBR band gap, which is explained in the Fano picture. The number density of the transmission peaks increases with increasing number of cells of the DBR, while the ratio of the average full width at half maximum to the corresponding average free spectral range, being only few percent for both transversal electric and magnetic waves, is almost invariant. The transmission peaks can be narrower than 0.1 nm and are fully separated from each other in certain wavebands. We further prove that the transmission combs are robust against randomness in the heights of the DBR layers. Therefore, the proposed structure is a candidate for an ultra-narrow-band multichannel filter or polarizer.

  20. Magneto-Optic Fiber Gratings Useful for Dynamic Dispersion Management and Tunable Comb Filtering

    International Nuclear Information System (INIS)

    Bao-Jian, Wu; Xin, Lu; Kun, Qiu

    2010-01-01

    Intelligent control of dispersion management and tunable comb filtering in optical network applications can be performed by using magneto-optic fiber Bragg gratings (MFBGs). When a nonuniform magnetic field is applied to the MFBG with a constant grating period, the resulting grating response is equivalent to that of a conventional chirped grating. Under a linearly nonuniform magnetic field along the grating, a linear dispersion is achieved in the grating bandgap and the maximal dispersion slope can come to 1260 ps/nm 2 for a 10-mm-long fiber grating at 1550 nm window. Similarly, a Gaussian-apodizing sampled MFBG is also useful for magnetically tunable comb filtering, with potential application to clock recovery from return-to-zero optical signals and optical carrier tracking. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  1. Fiber optics frequency comb enabled linear optical sampling with operation wavelength range extension.

    Science.gov (United States)

    Liao, Ruolin; Wu, Zhichao; Fu, Songnian; Zhu, Shengnan; Yu, Zhe; Tang, Ming; Liu, Deming

    2018-02-01

    Although the linear optical sampling (LOS) technique is powerful enough to characterize various advanced modulation formats with high symbol rates, the central wavelength of a pulsed local oscillator (LO) needs to be carefully set according to that of the signal under test, due to the coherent mixing operation. Here, we experimentally demonstrate wideband LOS enabled by a fiber optics frequency comb (FOFC). Meanwhile, when the broadband FOFC acts as the pulsed LO, we propose a scheme to mitigate the enhanced sampling error arising in the non-ideal response of a balanced photodetector. Finally, precise characterizations of arbitrary 128 Gbps PDM-QPSK wavelength channels from 1550 to 1570 nm are successfully achieved, when a 101.3 MHz frequency spaced comb with a 3 dB spectral power ripple of 20 nm is used.

  2. Evaluation of hyaluronan from different sources: Streptococcus zooepidemicus, rooster comb, bovine vitreous, and human umbilical cord.

    Science.gov (United States)

    Shiedlin, Aviva; Bigelow, Russell; Christopher, William; Arbabi, Saman; Yang, Laura; Maier, Ronald V; Wainwright, Norman; Childs, Alice; Miller, Robert J

    2004-01-01

    Sodium hyaluronate (HA) is widely distributed in extracellular matrixes and can play a role in orchestrating cell function. Consequently, many investigators have looked at the effect of exogenous HA on cell behavior in vitro. HA can be isolated from several sources (e.g., bacterial, rooster comb, umbilical cord) and therefore can possess diverse impurities. This current study compares the measured impurities and the differences in biological activity between HA preparations from these sources. It was demonstrated that nucleic acid and protein content was highest in human umbilical cord and bovine vitreous HA and was low in bacterial and rooster comb HA. Macrophages exposed to human umbilical cord HA produced significantly higher amounts of TNF-alpha relative to control or bacterial-derived HA. These results indicate that the source of HA should be considered due to differences in the amounts and types of contaminants that could lead to widely different behaviors in vitro and in vivo.

  3. Characterization of Comb-Shaped Copolymers by Multidetection SEC, DLS and SANS

    Directory of Open Access Journals (Sweden)

    Giulia Gelardi

    2017-02-01

    Full Text Available PolyCarboxylate ether-based superplasticizers (PCEs are a type of comb-shaped copolymers used as polymeric dispersants in cementitious materials. PCEs have a high degree of dispersity, which limits the suitability of conventional characterization techniques, such as Size Exclusion Chromatography (SEC. Properties of PCEs strongly depend on their molecular structure and a comprehensive characterization is needed to fully understand the structure–property relationships. PCEs with well-defined molecular structures were synthesized to study their solution conformation by SEC and scattering techniques. The combined use of SEC, dynamic light scattering and small-angle neutron scattering allowed us to demonstrate the validity of a scaling law describing the radius of gyration of comb-shaped copolymers as a function of their molecular structure. Moreover, we show that the use of SEC with standard calibration, although widely spread, is not adequate for PCEs.

  4. Gigahertz dual-comb modelocked diode-pumped semiconductor and solid-state lasers

    Science.gov (United States)

    Link, S. M.; Mangold, M.; Golling, M.; Klenner, A.; Keller, U.

    2016-03-01

    We present a simple approach to generate simultaneously two gigahertz mode-locked pulse trains from a single gain element. A bi-refringent crystal in the laser cavity splits the one cavity beam into two cross-polarized and spatially separated beams. This polarization-duplexing is successfully demonstrated for both a semiconductor disk laser (i.e. MIXSEL) and a diode-pumped solid-state Nd:YAG laser. The beat between the two beams results in a microwave frequency comb, which represents a direct link between the terahertz optical frequencies and the electronically accessible microwave regime. This dual-output technique enables compact and cost-efficient dual-comb lasers for spectroscopy applications.

  5. ACADEMIC TRAINING: Probing nature with high precision; particle traps, laser spectroscopy and optical combs

    CERN Multimedia

    Françoise Benz

    2002-01-01

    17, 18, 19 June LECTURE SERIES from 11.00 to 12.00 hrs - Auditorium, bldg. 500 Probing nature with high precision; particle traps, laser spectroscopy and optical combs by G. GABRIELSE / Harvard University, USA Experiments with atomic energy scales probe nature and its symmetries with exquisite precision. Particle traps allow the manipulation of single charged particles for months at a time, allow the most accurate comparison of theory and experiment, and promise to allow better measurement of fundamental quantities like the fine structure constant. Ions and atoms can be probed with lasers that are phase locked to microwave frequency standards via optical combs, thus calibrating optical sources in terms of the official cesium second. A series of three lectures will illustrate what can be measured and discuss key techniques.  ACADEMIC TRAINING Françoise Benz Tel. 73127 francoise.benz@cern.ch

  6. Adaptive value of sex in microbial pathogens.

    Science.gov (United States)

    Michod, Richard E; Bernstein, Harris; Nedelcu, Aurora M

    2008-05-01

    Explaining the adaptive value of sex is one of the great outstanding problems in biology. The challenge comes from the difficulty in identifying the benefits provided by sex, which must outweigh the substantial costs of sex. Here, we consider the adaptive value of sex in viruses, bacteria and fungi, and particularly the information available on the adaptive role of sex in pathogenic microorganisms. Our general theme is that the varied aspects of sex in pathogens illustrate the varied issues surrounding the evolution of sex generally. These include, the benefits of sex (in the short- and long-term), as well as the costs of sex (both to the host and to the pathogen). For the benefits of sex (that is, its adaptive value), we consider three hypotheses: (i) sex provides for effective and efficient recombinational repair of DNA damages, (ii) sex provides DNA for food, and (iii) sex produces variation and reduces genetic associations among alleles under selection. Although the evolution of sex in microbial pathogens illustrates these general issues, our paper is not a general review of theories for the evolution of sex in all organisms. Rather, we focus on the adaptive value of sex in microbial pathogens and conclude that in terms of short-term benefits, the DNA repair hypothesis has the most support and is the most generally applicable hypothesis in this group. In particular, recombinational repair of DNA damages may substantially benefit pathogens when challenged by the oxidative defenses of the host. However, in the long-term, sex may help get rid of mutations, increase the rate of adaptation of the population, and, in pathogens, may infrequently create new infective strains. An additional general issue about sex illustrated by pathogens is that some of the most interesting consequences of sex are not necessarily the reasons for which sex evolved. For example, antibiotic resistance may be transferred by bacterial sex, but this transfer is probably not the reason sex

  7. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    Science.gov (United States)

    Kalaycı, Özlem A.; Duygulu, Özgür; Hazer, Baki

    2013-01-01

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na2S and Cd(CH3COO)2 simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether-THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV-vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV-vis absorbance spectra and fluorescence emission spectra.

  8. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Kalayc Latin-Small-Letter-Dotless-I , Oezlem A. [Bulent Ecevit University, Department of Physics (Turkey); Duygulu, Oezguer [TUBITAK Marmara Research Center, Materials Institute (Turkey); Hazer, Baki, E-mail: bkhazer@karaelmas.edu.tr [Bulent Ecevit University, Department of Chemistry (Turkey)

    2013-01-15

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na{sub 2}S and Cd(CH{sub 3}COO){sub 2} simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether-THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV-vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV-vis absorbance spectra and fluorescence emission spectra.

  9. Optical characterization of CdS nanoparticles embedded into the comb-type amphiphilic graft copolymer

    International Nuclear Information System (INIS)

    Kalaycı, Özlem A.; Duygulu, Özgür; Hazer, Baki

    2013-01-01

    This study refers to the synthesis and characterization of a novel organic/inorganic hybrid nanocomposite material containing cadmium sulfide (CdS) nanoparticles. For this purpose, a series of polypropylene (PP)-g-polyethylene glycol (PEG), PP-g-PEG comb-type amphiphilic graft copolymers were synthesized. PEGs with Mn = 400, 2000, 3350, and 8000 Da were used and the graft copolymers obtained were coded as PPEG400, PPEG2000, PPEG3350, and PPEG8000. CdS nanoparticles were formed in tetrahydrofuran solution of PP-g-PEG amphiphilic comb-type copolymer by the reaction between aqueous solutions of Na 2 S and Cd(CH 3 COO) 2 simultaneously. Micelle formation of PPEG2000 comb-type amphiphilic graft copolymer in both solvent/non-solvent (petroleum ether–THF) by transmission electron microscopy (TEM). The optical characteristics, size morphology, phase analysis, and dispersion of CdS nanoparticles embedded in PPEG400, PPEG2000, PPEG3350, and PPEG8000 comb-type amphiphilic graft copolymer micelles were determined by high resolution TEM (HRTEM), energy dispersive spectroscopy, UV–vis spectroscopy, and fluorescence emission spectroscopy techniques. The aggregate size of PPEG2000-CdS is between 10 and 50 nm; however, in the case of PPEG400-CdS, PPEG3350-CdS, and PPEG8000-CdS samples, it is up to approximately 100 nm. The size of CdS quantum dots in the aggregates for PPEG2000 and PPEG8000 samples was observed as 5 nm by HRTEM analysis, and this result was also supported by UV–vis absorbance spectra and fluorescence emission spectra.

  10. Scaling of the first-passage time of biased diffusion on hierarchical comb structures

    International Nuclear Information System (INIS)

    Lin Zhifang; Tao Ruibao.

    1989-12-01

    Biased diffusion on hierarchical comb structures is studied within an exact renormalization group scheme. The scaling exponents of the moments of the first-passage time for random walks are obtained. It is found that the scaling properties of the diffusion depend only on the direction of bias. In this particular case, the presence of bias may give rise to a new multifractality. (author). 7 refs, 2 figs

  11. High-resolution broadband terahertz spectroscopy via electronic heterodyne detection of photonically generated terahertz frequency comb.

    Science.gov (United States)

    Pavelyev, D G; Skryl, A S; Bakunov, M I

    2014-10-01

    We report an alternative approach to the terahertz frequency-comb spectroscopy (TFCS) based on nonlinear mixing of a photonically generated terahertz pulse train with a continuous wave signal from an electronic synthesizer. A superlattice is used as a nonlinear mixer. Unlike the standard TFCS technique, this approach does not require a complex double-laser system but retains the advantages of TFCS-high spectral resolution and wide bandwidth.

  12. Spletna aplikacija microCOMB za določanje komponent genske ekspresije

    OpenAIRE

    SKOK, BOŠTJAN

    2017-01-01

    Cilj diplomskega dela je bil izdelati spletno aplikacijo, ki deluje kot grafični vmesnik za uporabnike microCOMB-a in vzdržuje bazo genskih ekspresij. Glavne funkcije aplikacije so omogočiti uporabnikom posredovanje ekspresijskih podatkov v analizo in prikazati njene rezultate, vodenje zgodovine analiz in skrbeti za ažurnost javne baze ekspresijskih podatkov. V delu so opisane uporabljene tehnologije, arhitektura sistema, razvojni proces ter končna funkcionalnost aplikacije. Ob razvoju smo st...

  13. microCOMB web application for the identification of gene expression components

    OpenAIRE

    Skok, Boštjan

    2016-01-01

    The goal of this thesis is to develop a web application that functions as user interface for microCOMB and manages it's gene expression database. The main functions of the application are to enable the user to upload expression profiles to be analyzed and show it's result, store user history of completed analyses and keep the public database up to date. In the thesis we describe the technologies used, architecture, development process and application functionality. During the development and ...

  14. SYNTHESIS OF AMPHIPHILIC COMB-SHAPED COPOLYMERS USED FOR SURFACE MODIFICATION OF PVDF MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    徐又一

    2009-01-01

    The synthesis of a novel amphiphilic comb-shaped copolymer consisting of a main chain of styrene-(N-(4- hydroxyphenyl) maleimide)(SHMI) copolymer and poly(ethylene glycol) methyl ether methacrylate(PEGMA) side groups was achieved by atom transfer radical polymerization(ATRP).The amphiphilic copolymers were characterized by ~1H-NMR, Fourier transform infrared(FTIR) spectroscopy and gel permeation chromatography(GPC).From thermogravimetric analysis (TGA),the decomposition temperature of SHMI-g-PEGMA is low...

  15. A near infrared laser frequency comb for high precision Doppler planet surveys

    Directory of Open Access Journals (Sweden)

    Bally J.

    2011-07-01

    Full Text Available Perhaps the most exciting area of astronomical research today is the study of exoplanets and exoplanetary systems, engaging the imagination not just of the astronomical community, but of the general population. Astronomical instrumentation has matured to the level where it is possible to detect terrestrial planets orbiting distant stars via radial velocity (RV measurements, with the most stable visible light spectrographs reporting RV results the order of 1 m/s. This, however, is an order of magnitude away from the precision needed to detect an Earth analog orbiting a star such as our sun, the Holy Grail of these efforts. By performing these observations in near infrared (NIR there is the potential to simplify the search for distant terrestrial planets by studying cooler, less massive, much more numerous class M stars, with a tighter habitable zone and correspondingly larger RV signal. This NIR advantage is undone by the lack of a suitable high precision, high stability wavelength standard, limiting NIR RV measurements to tens or hundreds of m/s [1, 2]. With the improved spectroscopic precision provided by a laser frequency comb based wavelength reference producing a set of bright, densely and uniformly spaced lines, it will be possible to achieve up to two orders of magnitude improvement in RV precision, limited only by the precision and sensitivity of existing spectrographs, enabling the observation of Earth analogs through RV measurements. We discuss the laser frequency comb as an astronomical wavelength reference, and describe progress towards a near infrared laser frequency comb at the National Institute of Standards and Technology and at the University of Colorado where we are operating a laser frequency comb suitable for use with a high resolution H band astronomical spectrograph.

  16. Evidence for paralytic shellfish poisons in the freshwater cyanobacterium Lyngbya wollei (Farlow ex Gomont) comb. nov.

    OpenAIRE

    Carmichael, W W; Evans, W R; Yin, Q Q; Bell, P; Moczydlowski, E

    1997-01-01

    Lyngbya wollei (Farlow ex Gomont) comb. nov., a perennial mat-forming filamentous cyanobacterium prevalent in lakes and reservoirs of the southeastern United States, was found to produce a potent, acutely lethal neurotoxin when tested in the mouse bioassay. Signs of poisoning were similar to those of paralytic shellfish poisoning. As part of the Tennessee Valley Authority master plan for Guntersville Reservoir, the mat-forming filamentous cyanobacterium L. wollei, a species that had recently ...

  17. Conformation of comb liquid crystal polymers by neutron small angle scattering

    International Nuclear Information System (INIS)

    Noirez, L.; Pepy, G.

    1988-01-01

    A review is made of the direct information obtained by small angle neutron scattering about the anisotropy of the components parallel and perpendicular to the orienting magnetic field of the radius of gyration of comb like liquid crystal polymers. The behaviour of the conformation versus temperature is reported for several samples. Until now all samples show an oblate conformation in the smectic phase and probably the whole range of the nematic phase. The results are compared with the available theoretical predictions

  18. Repetition rate multiplication of frequency comb using all-pass fiber resonator

    International Nuclear Information System (INIS)

    Yang, Lijun; Yang, Honglei; Zhang, Hongyuan; Wei, Haoyun; Li, Yan

    2016-01-01

    We propose a stable method for repetition rate multiplication of a 250-MHz Er-fiber frequency comb by a phase-locked all-pass fiber ring resonator, whose phase-locking configuration is simple. The optical path length of the fiber ring resonator is automatically controlled to be accurately an odd multiple of half of the original cavity length using an electronical phase-locking unit with an optical delay line. As for shorter cavity length of the comb, high-order odd multiple is preferable. Because the power loss depends only on the net-attenuation of the fiber ring resonator, the energetic efficiency of the proposed method is high. The input and output optical spectrums show that the spectral width of the frequency comb is clearly preserved. Besides, experimental results show less pulse intensity fluctuation and 35 dB suppression ratio of side-modes while providing a good long-term and short-term frequency stability. Higher-order repetition rate multiplication to several GHz can be obtained by using several fiber ring resonators in cascade configuration.

  19. Repetition rate multiplication of frequency comb using all-pass fiber resonator

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lijun; Yang, Honglei; Zhang, Hongyuan; Wei, Haoyun; Li, Yan, E-mail: liyan@mail.tsinghua.edu.cn [State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084 (China)

    2016-09-15

    We propose a stable method for repetition rate multiplication of a 250-MHz Er-fiber frequency comb by a phase-locked all-pass fiber ring resonator, whose phase-locking configuration is simple. The optical path length of the fiber ring resonator is automatically controlled to be accurately an odd multiple of half of the original cavity length using an electronical phase-locking unit with an optical delay line. As for shorter cavity length of the comb, high-order odd multiple is preferable. Because the power loss depends only on the net-attenuation of the fiber ring resonator, the energetic efficiency of the proposed method is high. The input and output optical spectrums show that the spectral width of the frequency comb is clearly preserved. Besides, experimental results show less pulse intensity fluctuation and 35 dB suppression ratio of side-modes while providing a good long-term and short-term frequency stability. Higher-order repetition rate multiplication to several GHz can be obtained by using several fiber ring resonators in cascade configuration.

  20. Clustering of comb and propolis waxes based on the distribution of aliphatic constituents

    Directory of Open Access Journals (Sweden)

    Custodio Angela R.

    2003-01-01

    Full Text Available Chemical composition data for 41 samples of propolis waxes and 9 samples of comb waxes of Apis mellifera collected mainly in Brazil were treated using Principal Component Analysis (PCA and Hierarchical Cluster Analysis (HCA. For chemometrical analysis, the distribution of hydrocarbons and residues of alcohols and carboxylic acids of monoesters were considered. The clustering obtained revealed chemical affinities and differences not previously grasped by simple eye-inspection of the data. No consistent differences were detected between comb and propolis waxes. These and previous results suggest that hydrocarbons, carboxylic acids, aliphatic alcohols and esters from both comb and propolis waxes are bee-produced compounds and, hence, the differences detected between one and another region are dependent on genetic factors related to the insects rather than the local flora. The samples analyzed were split into two main clusters, one of them comprising exclusively material collected in the State of São Paulo. The results are discussed with respect to the africanization of honeybees that first took place in that State and therefrom irradiated to other parts of Brazil.

  1. COMBS: open source python library for RVE generation - Application to microscale diffusion simulations in cementitious materials

    International Nuclear Information System (INIS)

    Bourcier, C.; Laucoin, E.; Dridi, W.; Chomat, L.; Bary, B.; Adam, E.

    2013-01-01

    In the context of radioactive waste storage and disposal, the knowledge of the concrete diffusivity is primordial in the numerical simulations of the long term behavior of these materials. COMBS is an open source python library, it is used to define the shapes of the inclusions, to insert them in the box featuring the representative volume element (RVE) of the cementitious medium, and to assess their diffusive properties. The algorithms developed in COMBS target a fast placement of the inclusions and a fast generation of the RVE shape and mesh. Two application cases are considered: the unaltered material diffusivity and the degraded material diffusivity. The first case of application focuses on the description of the capillary porosity. The second application case focuses on the description of the degradation of cementitious material (mineral and porosity) and the diffusive properties associated. The reliability of the analytical effective medium approximations (MT and SC) is confirmed from 3D finite elements (FE) calculations performed on a matrix-inclusions microstructure obtained by RVE generation with Combs. The results also show the need to take into account the percolation behavior

  2. A comb-sampling method for enhanced mass analysis in linear electrostatic ion traps

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, J. B.; Kelly, O.; Calvert, C. R.; Duffy, M. J.; King, R. B.; Belshaw, L.; Graham, L.; Alexander, J. D.; Williams, I. D. [Centre for Plasma Physics, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Bryan, W. A. [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Turcu, I. C. E.; Cacho, C. M.; Springate, E. [Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2011-04-15

    In this paper an algorithm for extracting spectral information from signals containing a series of narrow periodic impulses is presented. Such signals can typically be acquired by pickup detectors from the image-charge of ion bunches oscillating in a linear electrostatic ion trap, where frequency analysis provides a scheme for high-resolution mass spectrometry. To provide an improved technique for such frequency analysis, we introduce the CHIMERA algorithm (Comb-sampling for High-resolution IMpulse-train frequency ExtRAaction). This algorithm utilizes a comb function to generate frequency coefficients, rather than using sinusoids via a Fourier transform, since the comb provides a superior match to the data. This new technique is developed theoretically, applied to synthetic data, and then used to perform high resolution mass spectrometry on real data from an ion trap. If the ions are generated at a localized point in time and space, and the data is simultaneously acquired with multiple pickup rings, the method is shown to be a significant improvement on Fourier analysis. The mass spectra generated typically have an order of magnitude higher resolution compared with that obtained from fundamental Fourier frequencies, and are absent of large contributions from harmonic frequency components.

  3. Analysis of Oblique Wave Interaction with a Comb-Type Caisson Breakwater

    Science.gov (United States)

    Wang, Xinyu; Liu, Yong; Liang, Bingchen

    2018-04-01

    This study develops an analytical solution for oblique wave interaction with a comb-type caisson breakwater based on linear potential theory. The fluid domain is divided into inner and outer regions according to the geometrical shape of breakwater. By using periodic boundary condition and separation of variables, series solutions of velocity potentials in inner and outer regions are developed. Unknown expansion coefficients in series solutions are determined by matching velocity and pressure of continuous conditions on the interface between two regions. Then, hydrodynamic quantities involving reflection coefficients and wave forces acting on breakwater are estimated. Analytical solution is validated by a multi-domain boundary element method solution for the present problem. Diffusion reflection due to periodic variations in breakwater shape and corresponding surface elevations around the breakwater are analyzed. Numerical examples are also presented to examine effects of caisson parameters on total wave forces acting on caissons and total wave forces acting on side plates. Compared with a traditional vertical wall breakwater, the wave force acting on a suitably designed comb-type caisson breakwater can be significantly reduced. This study can give a better understanding of the hydrodynamic performance of comb-type caisson breakwaters.

  4. Intercomparison of open-path trace gas measurements with two dual-frequency-comb spectrometers

    Directory of Open Access Journals (Sweden)

    E. M. Waxman

    2017-09-01

    Full Text Available We present the first quantitative intercomparison between two open-path dual-comb spectroscopy (DCS instruments which were operated across adjacent 2 km open-air paths over a 2-week period. We used DCS to measure the atmospheric absorption spectrum in the near infrared from 6023 to 6376 cm−1 (1568 to 1660 nm, corresponding to a 355 cm−1 bandwidth, at 0.0067 cm−1 sample spacing. The measured absorption spectra agree with each other to within 5 × 10−4 in absorbance without any external calibration of either instrument. The absorption spectra are fit to retrieve path-integrated concentrations for carbon dioxide (CO2, methane (CH4, water (H2O, and deuterated water (HDO. The retrieved dry mole fractions agree to 0.14 % (0.57 ppm for CO2, 0.35 % (7 ppb for CH4, and 0.40 % (36 ppm for H2O at  ∼  30 s integration time over the 2-week measurement campaign, which included 24 °C outdoor temperature variations and periods of strong atmospheric turbulence. This agreement is at least an order of magnitude better than conventional active-source open-path instrument intercomparisons and is particularly relevant to future regional flux measurements as it allows accurate comparisons of open-path DCS data across locations and time. We additionally compare the open-path DCS retrievals to a World Meteorological Organization (WMO-calibrated cavity ring-down point sensor located along the path with good agreement. Short-term and long-term differences between the open-path DCS and point sensor are attributed, respectively, to spatial sampling discrepancies and to inaccuracies in the current spectral database used to fit the DCS data. Finally, the 2-week measurement campaign yields diurnal cycles of CO2 and CH4 that are consistent with the presence of local sources of CO2 and absence of local sources of CH4.

  5. Nuclear charge radii of light isotopes based on frequency comb measurements

    International Nuclear Information System (INIS)

    Zakova, Monika

    2010-01-01

    Optical frequency comb technology has been used in this work for the first time to investigate the nuclear structure of light radioactive isotopes. Therefore, three laser systems were stabilized with different techniques to accurately known optical frequencies and used in two specialized experiments. Absolute transition frequency measurements of lithium and beryllium isotopes were performed with accuracy on the order of 10 -10 . Such a high accuracy is required for the light elements since the nuclear volume effect has only a 10 -9 contribution to the total transition frequency. For beryllium, the isotope shift was determined with an accuracy that is sufficient to extract information about the proton distribution inside the nucleus. A Doppler-free two-photon spectroscopy on the stable lithium isotopes 6,7 Li was performed in order to determine the absolute frequency of the 2S → 3S transition. The achieved relative accuracy of 2 x 10 -10 is improved by one order of magnitude compared to previous measurements. The results provide an opportunity to determine the nuclear charge radius of the stable and short-lived isotopes in a pure optical way but this requires an improvement of the theoretical calculations by two orders of magnitude. The second experiment presented here was performed at ISOLDE/CERN, where the absolute transition frequencies of the D 1 and D 2 lines in beryllium ions for the isotopes 7,9,10,11 Be were measured with an accuracy of about 1 MHz. Therefore, an advanced collinear laser spectroscopy technique involving two counter-propagating frequency-stabilized laser beams with a known absolute frequency was developed. The extracted isotope shifts were combined with recent accurate mass shift calculations and the root-mean square nuclear charge radii of 7,10 Be and the one-neutron halo nucleus 11 Be were determined. Obtained charge radii are decreasing from 7 Be to 10 Be and increasing again for 11 Be. While the monotone decrease can be explained by a

  6. Demonstration of a near-IR line-referenced electro-optical laser frequency comb for precision radial velocity measurements in astronomy.

    Science.gov (United States)

    Yi, X; Vahala, K; Li, J; Diddams, S; Ycas, G; Plavchan, P; Leifer, S; Sandhu, J; Vasisht, G; Chen, P; Gao, P; Gagne, J; Furlan, E; Bottom, M; Martin, E C; Fitzgerald, M P; Doppmann, G; Beichman, C

    2016-01-27

    An important technique for discovering and characterizing planets beyond our solar system relies upon measurement of weak Doppler shifts in the spectra of host stars induced by the influence of orbiting planets. A recent advance has been the introduction of optical frequency combs as frequency references. Frequency combs produce a series of equally spaced reference frequencies and they offer extreme accuracy and spectral grasp that can potentially revolutionize exoplanet detection. Here we demonstrate a laser frequency comb using an alternate comb generation method based on electro-optical modulation, with the comb centre wavelength stabilized to a molecular or atomic reference. In contrast to mode-locked combs, the line spacing is readily resolvable using typical astronomical grating spectrographs. Built using commercial off-the-shelf components, the instrument is relatively simple and reliable. Proof of concept experiments operated at near-infrared wavelengths were carried out at the NASA Infrared Telescope Facility and the Keck-II telescope.

  7. Review of the comb-tailed spider genus Hahnia C.L. Koch 1841 (Hahniidae) from Gaoligong Mountains in Yunnan, China.

    Science.gov (United States)

    Huang, Gui-Qiang; Zhang, Zhi-Sheng; Liu, Ying-Hong

    2017-11-08

    Gaoligong Mountains in Yunnan, China are famous for the biodiversity and are part of Indo-Burmese hotspot. We present a review on the comb-tailed spider genus Hahnia C.L. Koch 1841 based on newly collected specimens. Four new species of Hahnia are described: H. biapophysis sp. nov. (male), H. dongi sp. nov. (male), H. subsaccata sp. nov. (male, female) and H. wangi sp. nov. (male, female). Two additional known species are redescribed: H. himalayaensis Hu & Zhang, 1990 and H. musica Brignoli, 1978. Hahnia musica previously known from Bhutan is recorded from China for the first time. Photos of habitus and genitalia of all species and additionally illustrations of new species are given.

  8. Sex. Dev.

    OpenAIRE

    Jakubiczka, S.; Schröder, C.; Ullmann, R.; Volleth, M.; Ledig, S.; Gilberg, E.; Kroisel, P.; P. Wieacker, P.

    2010-01-01

    Campomelic dysplasia (MIM 114290) is a severe malformation syndrome frequently accompanied by male-to-female sex reversal. Causative are mutations within the SOX9 gene on 17q24.3 as well as chromosomal aberrations (translocations, inversions or deletions) in the vicinity of SOX9 . Here, we report on a patient with muscular hypotonia, craniofacial dysmorphism, cleft palate, brachydactyly, malformations of thoracic spine, and gonadal dysgenesis with female external genitalia and müllerian duct ...

  9. Additive manufacturing.

    Science.gov (United States)

    Mumith, A; Thomas, M; Shah, Z; Coathup, M; Blunn, G

    2018-04-01

    Increasing innovation in rapid prototyping (RP) and additive manufacturing (AM), also known as 3D printing, is bringing about major changes in translational surgical research. This review describes the current position in the use of additive manufacturing in orthopaedic surgery. Cite this article: Bone Joint J 2018;100-B:455-60.

  10. Distance measurement using frequency-modulated continuous-wave ladar with calibration by a femtosecond frequency comb

    Science.gov (United States)

    Liu, Yang; Yang, Linghui; Lin, Jiarui; Zhu, Jigui

    2018-01-01

    Precise distance measurement is of interest for large-scale manufacturing, future space satellite missions, and other industrial applications. The ranging system with femtosecond optical frequency comb (FOFC) could offer high accuracy, stability and direct traceability to SI definition of the meter. Here, we propose a scheme for length measurement based on the frequency-modulated continuous-wave (FMCW) ladar with a FOFC. In this scheme, the reference interferometer in the FMCW ladar is calibrated by the intensity detection using the FOFC in the time domain within an optical wavelength resolution. With analysis of the theoretical model, this system has the potential to a high-speed, high-accuracy absolute distance measurement. Then, based on the experimental results, the evaluation of the performance of the calibration of the reference arm is discussed. In addition, the performance of this system is evaluated by a single position measurement with different tuning velocities of wavelength. The experimental results show that the reproducibility of the distance measurement is 10-5 level.

  11. When Sex Is Painful

    Science.gov (United States)

    ... AQ FREQUENTLY ASKED QUESTIONS GYNECOLOGIC PROBLEMS FAQ020 When Sex Is Painful • How common is painful sex? • What causes pain during sex? • Where is pain during sex felt? • When should ...

  12. Sex during Pregnancy

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Sex During Pregnancy KidsHealth / For Parents / Sex During Pregnancy ... satisfying and safe sexual relationship during pregnancy. Is Sex During Pregnancy Safe? Sex is considered safe during ...

  13. Food additives

    Science.gov (United States)

    ... GO About MedlinePlus Site Map FAQs Customer Support Health Topics Drugs & Supplements Videos & Tools Español You Are Here: Home → Medical Encyclopedia → Food additives URL of this page: //medlineplus.gov/ency/article/ ...

  14. A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s(-1).

    Science.gov (United States)

    Li, Chih-Hao; Benedick, Andrew J; Fendel, Peter; Glenday, Alexander G; Kärtner, Franz X; Phillips, David F; Sasselov, Dimitar; Szentgyorgyi, Andrew; Walsworth, Ronald L

    2008-04-03

    Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s(-1) (ref. 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of approximately 5 cm s(-1) is necessary. The combination of a laser frequency comb with a Fabry-Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (approximately 1-A) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or 'astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s(-1) in astronomical radial velocity measurements.

  15. Sex work among men who have sex with men and transgender women in Bogotá.

    Science.gov (United States)

    Bianchi, Fernanda T; Reisen, Carol A; Zea, Maria Cecilia; Vidal-Ortiz, Salvador; Gonzales, Felisa A; Betancourt, Fabián; Aguilar, Marcela; Poppen, Paul J

    2014-11-01

    This qualitative study examined sex work among internally displaced male and transgender female sex workers in Bogotá, Colombia. Internal displacement has occurred in Colombia as a result of decades of conflict among armed groups and has created large-scale migration from rural to urban areas. Informed by the polymorphous model of sex work, which posits that contextual conditions shape the experience of sex work, we examined three main research questions. The first dealt with how internal displacement was related to the initiation of sex work; the second concerned the effect of agency on sex worker satisfaction; and the third examined how sex work in this context was related to HIV and other risks. Life history interviews were conducted with 26 displaced individuals who had done sex work: 14 were men who have sex with men and 12 were transgender women (natal males). Findings revealed that many participants began doing sex work in the period immediately after displacement, because of a lack of money, housing, and social support. HIV risk was greater during this time due to limited knowledge of HIV and inexperience negotiating safer sex with clients. Other findings indicated that sex workers who exerted more control and choice in the circumstances of their work reported greater satisfaction. In addition, we found that although many sex workers insisted on condom use with clients, several noted that they would sometimes have unprotected sex for additional money. Specific characteristics affecting the experience of sex work among the transgender women were also discussed.

  16. Combing and self-assembly phenomena in dry films of Taxol-stabilized microtubules

    Directory of Open Access Journals (Sweden)

    Rose Franck

    2007-01-01

    Full Text Available AbstractMicrotubules are filamentous proteins that act as a substrate for the translocation of motor proteins. As such, they may be envisioned as a scaffold for the self-assembly of functional materials and devices. Physisorption, self-assembly and combing are here investigated as a potential prelude to microtubule-templated self-assembly. Dense films of self-assembled microtubules were successfully produced, as well as patterns of both dendritic and non-dendritic bundles of microtubules. They are presented in the present paper and the mechanism of their formation is discussed.

  17. Generation of optical frequencies out of the frequency comb of a femtosecond laser for DWDM telecommunication

    International Nuclear Information System (INIS)

    Kim, Y-J; Chun, B J; Kim, Y; Hyun, S; Kim, S-W

    2010-01-01

    We exploit the frequency comb of a fs laser as the frequency ruler to generate reference optical frequencies for multi-channel DWDM (dense wavelength-division-multiplexing) telecommunication. Our fiber-based scheme of single-mode extraction enables on-demand generation of optical frequencies within the telecommunication band with an absolute frequency uncertainty of 9.1×10 -13 . The linewidth of extracted optical modes is less than 1 Hz, and the instability is measured 2.3×10 -15 at 10 s averaging. This outstanding performance of optical frequency generation would lead to a drastic improvement of the spectral efficiency for the next-generation DWDM telecommunication

  18. Dual-etalon cavity ring-down frequency-comb spectroscopy with broad band light source

    Science.gov (United States)

    Chandler, David W; Strecker, Kevin E

    2014-04-01

    In an embodiment, a dual-etalon cavity-ring-down frequency-comb spectrometer system is described. A broad band light source is split into two beams. One beam travels through a first etalon and a sample under test, while the other beam travels through a second etalon, and the two beams are recombined onto a single detector. If the free spectral ranges ("FSR") of the two etalons are not identical, the interference pattern at the detector will consist of a series of beat frequencies. By monitoring these beat frequencies, optical frequencies where light is absorbed may be determined.

  19. Multiple trapping on a comb structure as a model of electron transport in disordered nanostructured semiconductors

    International Nuclear Information System (INIS)

    Sibatov, R. T.; Morozova, E. V.

    2015-01-01

    A model of dispersive transport in disordered nanostructured semiconductors has been proposed taking into account the percolation structure of a sample and joint action of several mechanisms. Topological and energy disorders have been simultaneously taken into account within the multiple trapping model on a comb structure modeling the percolation character of trajectories. The joint action of several mechanisms has been described within random walks with a mixture of waiting time distributions. Integral transport equations with fractional derivatives have been obtained for an arbitrary density of localized states. The kinetics of the transient current has been calculated within the proposed new model in order to analyze time-of-flight experiments for nanostructured semiconductors

  20. Description of Noviherbaspirillum malthae gen. nov., sp. nov., isolated from an oil-contaminated soil, and proposal to reclassify Herbaspirillum soli, Herbaspirillum aurantiacum, Herbaspirillum canariense and Herbaspirillum psychrotolerans as Noviherbaspirillum soli comb. nov., Noviherbaspirillum aurantiacum comb. nov., Noviherbaspirillum canariense comb. nov. and Noviherbaspirillum psychrotolerans comb. nov. based on polyphasic analysis.

    Science.gov (United States)

    Lin, Shih-Yao; Hameed, Asif; Arun, A B; Liu, You-Cheng; Hsu, Yi-Han; Lai, Wei-An; Rekha, P D; Young, Chiu-Chung

    2013-11-01

    An aerobic, Gram-negative, rod-shaped bacterium with polar flagella, strain CC-AFH3(T), was isolated from an oil-contaminated site located in Kaohsiung county, Taiwan. Strain CC-AFH3(T) grew at 20-40 °C, pH 5.0-10.0 and Herbaspirillum soli SUEMI10(T) (96.5 %), H. aurantiacum SUEMI08(T) (96.3 %), H. canariense SUEMI03(T) (96.0 %), H. psychrotolerans PB1(T) (95.4 %) and members of other Herbaspirillum species (94.1-95.2 %), and lower similarity to members of other genera (Herbaspirillum as an independent lineage. The major fatty acids in strain CC-AFH3(T) were C10 : 0 3-OH, C12 : 0, C14 : 0 2-OH, C16 : 0, iso-C15 : 0 3-OH, C17 : 0 cyclo, C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω7c/C18 : 1ω6c. The major polar lipids of strain CC-AFH3(T) were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. The predominant quinone was ubiquinone 8 (Q-8) and the DNA G+C content was 63.4 mol%. On the basis of 16S rRNA gene sequence analysis in combination with physiological and chemotaxonomic data, strain CC-AFH3(T) represents a novel species in a new genus, for which we propose the name Noviherbaspirillum malthae gen. nov., sp. nov.; the type strain of Noviherbaspirillum malthae is CC-AFH3(T) ( = BCRC 80516(T) = JCM 18414(T)). We also propose the reclassification of Herbaspirillum soli, Herbaspirillum aurantiacum, Herbaspirillum canariense and 'Herbaspirillum psychrotolerans' as Noviherbaspirillum soli comb. nov. (type strain SUEMI10(T) = LMG 26149(T) = CECT 7840(T)), Noviherbaspirillum aurantiacum comb. nov. (type strain SUEMI08(T) = LMG 26150(T) = CECT 7839(T)), Noviherbaspirillum canariense comb. nov. (type strain SUEMI03(T) = LMG 26151(T) = CECT 7838(T)) and Noviherbaspirillum psychrotolerans comb. nov. (type strain PB1(T) = DSM 26001(T) = LMG 27282(T)), respectively. An emended description of Herbaspirillum seropedicae is also presented.

  1. Sex Education

    Directory of Open Access Journals (Sweden)

    R N Srivastava

    1994-06-01

    Full Text Available Sex, though not everything in life, is a profoundly important aspect of human existence. It has evolved to serve more than reproductive functions; relational and recreational functions having taken precedence over procrea­tional. Sex has come to play a much wider socio-psychological function. Human sexuality is complex and multidimensional. It is subject to influence by multitude of factors often grouped as biological (e.g. genes, hormones, psychological (e.g. fear, anxiety, mood and socio-cultural (e.g. sex roles, values- religious/moral/ethical, customs. It is the interaction and interrelationship of these factors from the time of conception, through intrauterine life, infancy, childhood and adolescence, till adulthood (even later in life that determine the sexual development expressed as sexual attitudes and behaviour of the people. Learning, both social and cognitive, plays a significantly important role in such development. Sexual dysfunctions in men and women, result from factors often categorised as physical or organic and psychological; more often a combination may be involved. Experience has shown that in majority of men and women in India having sexual problems, ignorance misconceptions and prevailing myths are invariably responsible in the causation of Ihese problems. Sexual problems in individual man (e.g. erectile failure and woman (e.g. vaginismus cause anxiety, feelings of frustration, lowered self esteem and symptoms of depression. The condition may also affect the spouse; he/she, as a reaction to the problem in the partner, may develop sexual and psychosocial problems including distressed marital relationship. This may also have influence on general couple relationship, effecting adversely the quality of family life. Modern therapeutic endevours have made it possible now to offer effective therapy to most people who seek help for their sexual problems, thus preventing the consequences on couple relationship. However, there is

  2. SEX EDUCATION

    Directory of Open Access Journals (Sweden)

    R N Srivastava

    1994-06-01

    Full Text Available Sex, though not everything in life, is a profoundly important aspect of human existence. It has evolved to serve more than reproductive functions; relational and recreational functions having taken precedence over procrea­tional. Sex has come to play a much wider socio-psychological function.Human sexuality is complex and multidimensional. It is subject to influence by multitude of factors often grouped as biological (e.g. genes, hormones, psychological (e.g. fear, anxiety, mood and socio-cultural (e.g. sex roles, values- religious/moral/ethical, customs. It is the interaction and interrelationship of these factors from the time of conception, through intrauterine life, infancy, childhood and adolescence, till adulthood (even later in life that determine the sexual development expressed as sexual attitudes and behaviour of the people. Learning, both social and cognitive, plays a significantly important role in such development.Sexual dysfunctions in men and women, result from factors often categorised as physical or organic and psychological; more often a combination may be involved. Experience has shown that in majority of men and women in India having sexual problems, ignorance misconceptions and prevailing myths are invariably responsible in the causation of Ihese problems. Sexual problems in individual man (e.g. erectile failure and woman (e.g. vaginismus cause anxiety, feelings of frustration, lowered self esteem and symptoms of depression. The condition may also affect the spouse; he/she, as a reaction to the problem in the partner, may develop sexual and psychosocial problems including distressed marital relationship. This may also have influence on general couple relationship, effecting adversely the quality of family life.Modern therapeutic endevours have made it possible now to offer effective therapy to most people who seek help for their sexual problems, thus preventing the consequences on couple relationship. However, there is also

  3. Comb-like optical transmission spectrum resulting from a four-cornered two-waveguide-connected network

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiangbo, E-mail: xbyang@scnu.edu.cn [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); School of Physical Education and Sports Science, South China Normal University, Guangzhou 510006 (China); Song, Huanhuan [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Liu, Timon Chengyi [School of Physical Education and Sports Science, South China Normal University, Guangzhou 510006 (China)

    2013-12-06

    In this Letter a four-cornered two-waveguide-connected network (FCTWCN) is proposed to generate comb-like optical transmission spectrum, where nearest-neighbor nodes are connected by two segments of one-dimensional waveguides. We investigate the band structure and transmission spectrum of electromagnetic waves propagating through FCTWCNs and find that the transmission through a FCTWCN exhibits periodic comb-like characteristic and the range, number and width of continuous equidistant frequency bands can be controlled by adjusting the lengths of the two types of segments. The comb-like frequency bands may be useful for the designing of optical switches, optical narrowband filters, high capacity telecommunications, and multichannel filters, etc.

  4. Absolute distance measurement by dual-comb interferometry with multi-channel digital lock-in phase detection

    International Nuclear Information System (INIS)

    Yang, Ruitao; Pollinger, Florian; Meiners-Hagen, Karl; Krystek, Michael; Bosse, Harald; Tan, Jiubin

    2015-01-01

    We present a dual-comb-based heterodyne multi-wavelength absolute interferometer capable of long distance measurements. The phase information of the various comb modes is extracted in parallel by a multi-channel digital lock-in phase detection scheme. Several synthetic wavelengths of the same order are constructed and the corresponding phases are averaged to deduce the absolute lengths with significantly reduced uncertainty. Comparison experiments with an incremental HeNe reference interferometer show a combined relative measurement uncertainty of 5.3 × 10 −7 at a measurement distance of 20 m. Combining the advantage of synthetic wavelength interferometry and dual-comb interferometry, our compact and simple approach provides sufficient precision for many industrial applications. (paper)

  5. Absolute distance measurement by dual-comb interferometry with multi-channel digital lock-in phase detection

    Science.gov (United States)

    Yang, Ruitao; Pollinger, Florian; Meiners-Hagen, Karl; Krystek, Michael; Tan, Jiubin; Bosse, Harald

    2015-08-01

    We present a dual-comb-based heterodyne multi-wavelength absolute interferometer capable of long distance measurements. The phase information of the various comb modes is extracted in parallel by a multi-channel digital lock-in phase detection scheme. Several synthetic wavelengths of the same order are constructed and the corresponding phases are averaged to deduce the absolute lengths with significantly reduced uncertainty. Comparison experiments with an incremental HeNe reference interferometer show a combined relative measurement uncertainty of 5.3 × 10-7 at a measurement distance of 20 m. Combining the advantage of synthetic wavelength interferometry and dual-comb interferometry, our compact and simple approach provides sufficient precision for many industrial applications.

  6. Adolescents, sex, and the media.

    Science.gov (United States)

    Strasburger, Victor C

    2012-04-01

    In the absence of effective sex education in the United States, the media have arguably become the leading sex educator for children and teenagers. Considerable research now exists that attests to the ability of the media to influence adolescents' attitudes and beliefs about sex and sexuality. In addition, new research has found a significant link between exposure to sexual content in the media and earlier onset of sexual intercourse. Although there is little research on the behavioral effects of "new" media, they are discussed as well. Suggestions for clinicians, parents, the federal government, and the entertainment industry are provided.

  7. Comparing the flight activities of workers from two stocks of honey bees (Apis mellifera) raised in gamma-irradiated combs using radio-frequency identification (RFID) technology

    Science.gov (United States)

    Gamma irradiation has been shown to inactivate pathogens (virus, American foulbrood and Nosema) that are harmful to honey bees. Preliminary data suggest that queens raised in mating nucleus colonies having gamma-irradiated combs outperformed queens from nucleus colonies not having irradiated combs. ...

  8. Generation of tunable, high repetition rate frequency combs with equalized spectra using carrier injection based silicon modulators

    Science.gov (United States)

    Nagarjun, K. P.; Selvaraja, Shankar Kumar; Supradeepa, V. R.

    2016-03-01

    High repetition-rate frequency combs with tunable repetition rate and carrier frequency are extensively used in areas like Optical communications, Microwave Photonics and Metrology. A common technique for their generation is strong phase modulation of a CW-laser. This is commonly implemented using Lithium-Niobate based modulators. With phase modulation alone, the combs have poor spectral flatness and significant number of missing lines. To overcome this, a complex cascade of multiple intensity and phase modulators are used. A comb generator on Silicon based on these principles is desirable to enable on-chip integration with other functionalities while reducing power consumption and footprint. In this work, we analyse frequency comb generation in carrier injection based Silicon modulators. We observe an interesting effect in these comb generators. Enhanced absorption accompanying carrier injection, an undesirable effect in data modulators, shapes the amplitude here to enable high quality combs from a single modulator. Thus, along with reduced power consumption to generate a specific number of lines, the complexity has also been significantly reduced. We use a drift-diffusion solver and mode solver (Silvaco TCAD) along with Soref-Bennett relations to calculate the variations in refractive indices and absorption of an optimized Silicon PIN - waveguide modulator driven by an unbiased high frequency (10 Ghz) voltage signal. Our simulations demonstrate that with a device length of 1 cm, a driving voltage of 2V and minor shaping with a passive ring-resonator filter, we obtain 37 lines with a flatness better than 5-dB across the band and power consumption an order of magnitude smaller than Lithium-Niobate modulators.

  9. Nuclear charge radii of light isotopes based on frequency comb measurements

    Energy Technology Data Exchange (ETDEWEB)

    Zakova, Monika

    2010-02-11

    Optical frequency comb technology has been used in this work for the first time to investigate the nuclear structure of light radioactive isotopes. Therefore, three laser systems were stabilized with different techniques to accurately known optical frequencies and used in two specialized experiments. Absolute transition frequency measurements of lithium and beryllium isotopes were performed with accuracy on the order of 10{sup -10}. Such a high accuracy is required for the light elements since the nuclear volume effect has only a 10{sup -9} contribution to the total transition frequency. For beryllium, the isotope shift was determined with an accuracy that is sufficient to extract information about the proton distribution inside the nucleus. A Doppler-free two-photon spectroscopy on the stable lithium isotopes {sup 6,7}Li was performed in order to determine the absolute frequency of the 2S {yields} 3S transition. The achieved relative accuracy of 2 x 10{sup -10} is improved by one order of magnitude compared to previous measurements. The results provide an opportunity to determine the nuclear charge radius of the stable and short-lived isotopes in a pure optical way but this requires an improvement of the theoretical calculations by two orders of magnitude. The second experiment presented here was performed at ISOLDE/CERN, where the absolute transition frequencies of the D{sub 1} and D{sub 2} lines in beryllium ions for the isotopes {sup 7,9,10,11}Be were measured with an accuracy of about 1 MHz. Therefore, an advanced collinear laser spectroscopy technique involving two counter-propagating frequency-stabilized laser beams with a known absolute frequency was developed. The extracted isotope shifts were combined with recent accurate mass shift calculations and the root-mean square nuclear charge radii of {sup 7,10}Be and the one-neutron halo nucleus {sup 11}Be were determined. Obtained charge radii are decreasing from {sup 7}Be to {sup 10}Be and increasing again for

  10. Quantitative sexing (Q-Sexing) and relative quantitative sexing (RQ ...

    African Journals Online (AJOL)

    samer

    Key words: Polymerase chain reaction (PCR), quantitative real time polymerase chain reaction (qPCR), quantitative sexing, Siberian tiger. INTRODUCTION. Animal molecular sexing .... 43:3-12. Ellegren H (1996). First gene on the avian W chromosome (CHD) provides a tag for universal sexing of non-ratite birds. Proc.

  11. Microwave Frequency Comb from a Semiconductor in a Scanning Tunneling Microscope.

    Science.gov (United States)

    Hagmann, Mark J; Yarotski, Dmitry A; Mousa, Marwan S

    2017-04-01

    Quasi-periodic excitation of the tunneling junction in a scanning tunneling microscope, by a mode-locked ultrafast laser, superimposes a regular sequence of 15 fs pulses on the DC tunneling current. In the frequency domain, this is a frequency comb with harmonics at integer multiples of the laser pulse repetition frequency. With a gold sample the 200th harmonic at 14.85 GHz has a signal-to-noise ratio of 25 dB, and the power at each harmonic varies inversely with the square of the frequency. Now we report the first measurements with a semiconductor where the laser photon energy must be less than the bandgap energy of the semiconductor; the microwave frequency comb must be measured within 200 μm of the tunneling junction; and the microwave power is 25 dB below that with a metal sample and falls off more rapidly at the higher harmonics. Our results suggest that the measured attenuation of the microwave harmonics is sensitive to the semiconductor spreading resistance within 1 nm of the tunneling junction. This approach may enable sub-nanometer carrier profiling of semiconductors without requiring the diamond nanoprobes in scanning spreading resistance microscopy.

  12. Alignment of Gold Nanoparticle-Decorated DNA Origami Nanotubes: Substrate Prepatterning versus Molecular Combing.

    Science.gov (United States)

    Teschome, Bezu; Facsko, Stefan; Gothelf, Kurt V; Keller, Adrian

    2015-11-24

    DNA origami has become an established technique for designing well-defined nanostructures with any desired shape and for the controlled arrangement of functional nanostructures with few nanometer resolution. These unique features make DNA origami nanostructures promising candidates for use as scaffolds in nanoelectronics and nanophotonics device fabrication. Consequently, a number of studies have shown the precise organization of metallic nanoparticles on various DNA origami shapes. In this work, we fabricated large arrays of aligned DNA origami decorated with a high density of gold nanoparticles (AuNPs). To this end, we first demonstrate the high-yield assembly of high-density AuNP arrangements on DNA origami adsorbed to Si surfaces with few unbound background nanoparticles by carefully controlling the concentrations of MgCl2 and AuNPs in the hybridization buffer and the hybridization time. Then, we evaluate two methods, i.e., hybridization to prealigned DNA origami and molecular combing in a receding meniscus, with respect to their potential to yield large arrays of aligned AuNP-decorated DNA origami nanotubes. Because of the comparatively low MgCl2 concentration required for the efficient immobilization of the AuNPs, the prealigned DNA origami become mobile and displaced from their original positions, thereby decreasing the alignment yield. This increased mobility, on the other hand, makes the adsorbed origami susceptible to molecular combing, and a total alignment yield of 86% is obtained in this way.

  13. Rooster comb hyaluronate-protein, a non-covalently linked complex.

    Science.gov (United States)

    Tsiganos, C P; Vynios, D H; Kalpaxis, D L

    1986-01-01

    Hyaluronate from rooster comb was isolated by ion-exchange chromatography on DEAE-cellulose from tissue extracts and papain digests. The preparations were labelled with [14C]acetic anhydride and subjected to CsCl-density-gradient centrifugation in 4 M-guanidinium chloride in the presence and absence of 4% ZwittergentTM 3-12. A radioactive protein fraction was separated from the hyaluronate when the zwitterionic detergent was also present. The protein could also be separated from the glycosaminoglycan by chromatography on Sepharose CL-6B eluted with the same solvent mixture. The protein fraction contained three protein bands of Mr 15,000-17,000 as assessed by polyacrylamide-gel electrophoresis in 0.1% SDS, and seemed to lack lysozyme activity. No evidence of other protein or amino acid(s) covalently linked with the hyaluronate was obtained. The hyaluronate-protein complex may be re-formed upon mixing the components, the extent of its formation depending on the conditions used. The results show that, as in chondrosarcoma [Mason, d'Arville, Kimura & Hascall (1982) Biochem. J. 207, 445-457] and teratocarcinoma cells [Prehm (1983) Biochem. J. 211, 191-198] the rooster comb hyaluronate also is not linked covalently to a core protein. PMID:3741374

  14. Nonlinear dynamics of spring softening and hardening in folded-mems comb drive resonators

    KAUST Repository

    Elshurafa, Amro M.

    2011-08-01

    This paper studies analytically and numerically the spring softening and hardening phenomena that occur in electrostatically actuated microelectromechanical systems comb drive resonators utilizing folded suspension beams. An analytical expression for the electrostatic force generated between the combs of the rotor and the stator is derived and takes into account both the transverse and longitudinal capacitances present. After formulating the problem, the resulting stiff differential equations are solved analytically using the method of multiple scales, and a closed-form solution is obtained. Furthermore, the nonlinear boundary value problem that describes the dynamics of inextensional spring beams is solved using straightforward perturbation to obtain the linear and nonlinear spring constants of the beam. The analytical solution is verified numerically using a Matlab/Simulink environment, and the results from both analyses exhibit excellent agreement. Stability analysis based on phase plane trajectory is also presented and fully explains previously reported empirical results that lacked sufficient theoretical description. Finally, the proposed solutions are, once again, verified with previously published measurement results. The closed-form solutions provided are easy to apply and enable predicting the actual behavior of resonators and gyroscopes with similar structures. © 2011 IEEE.

  15. Optical Comb from a Whispering Gallery Mode Resonator for Spectroscopy and Astronomy Instruments Calibration

    Science.gov (United States)

    Strekalov, Dmitry V.; Yu, Nam; Thompson, Robert J.

    2012-01-01

    The most accurate astronomical data is available from space-based observations that are not impeded by the Earth's atmosphere. Such measurements may require spectral samples taken as long as decades apart, with the 1 cm/s velocity precision integrated over a broad wavelength range. This raises the requirements specifically for instruments used in astrophysics research missions -- their stringent wavelength resolution and accuracy must be maintained over years and possibly decades. Therefore, a stable and broadband optical calibration technique compatible with spaceflights becomes essential. The space-based spectroscopic instruments need to be calibrated in situ, which puts forth specific requirements to the calibration sources, mainly concerned with their mass, power consumption, and reliability. A high-precision, high-resolution reference wavelength comb source for astronomical and astrophysics spectroscopic observations has been developed that is deployable in space. The optical comb will be used for wavelength calibrations of spectrographs and will enable Doppler measurements to better than 10 cm/s precision, one hundred times better than the current state-of-the- art.

  16. PH- and salt-dependent molecular combing of DNA: experiments and phenomenological model

    International Nuclear Information System (INIS)

    Benke, Annegret; Pompe, Wolfgang; Mertig, Michael

    2011-01-01

    λ-DNA as well as plasmids can be successfully deposited by molecular combing on hydrophobic surfaces, for pH values ranging from 4 to 10. On polydimethylsiloxane (PDMS) substrates, the deposited DNA molecules are overstretched by about 60-100%. There is a significant influence of sodium ions (NaCl) on the surface density of the deposited DNA, with a maximum near to 100 mM NaCl for a DNA solution (28 ng μl -1 ) at pH 8. The combing process can be described by a micromechanical model including: (i) the adsorption of free moving coiled DNA at the substrate; (ii) the stretching of the coiled DNA by the preceding meniscus; (iii) the relaxation of the deposited DNA to the final length. The sticky ends of λ-DNA cause an adhesion force in the range of about 400 pN which allows a stable overstretching of the DNA by the preceding meniscus. The exposing of hidden hydrophobic bonds of the overstretched DNA leads to a stable deposition on the hydrophobic substrate. The pH-dependent density of deposited DNA as well as the observed influence of sodium ions can be explained by their screening of the negatively charged DNA backbone and sticky ends, respectively. The final DNA length can be derived from a balance of the stored elastic energy of the overstretched molecules and the energy of adhesion.

  17. Broadband Enhancement of Optical Frequency Comb Using Cascaded Four-Wave Mixing in Photonic Crystal Fiber

    Directory of Open Access Journals (Sweden)

    Tawfig Eltaif

    2017-01-01

    Full Text Available A cascaded intensity modulator (IM and phase modulator (PM are used to modulate a continuous-wave (CW laser and generate an optical frequency comb (OFC. Thus, the generated comb is utilized as an initial seed and combined with another CW-laser to generate four-wave mixing (FWM in photonic crystal fiber (PCF. Results show that an initial flat 30 GHz OFC of 29, 55 lines within power fluctuation of 0.8 dB and 2 dB, respectively, can be achieved by setting the ratio of the DC bias to amplitude of sinusoidal signal at 0.1 and setting the modulation indices of both IM and PM at 10. Moreover, the 1st order of FWM created through 14 m of PCF has over 68 and 94 lines with fluctuation of 0.8 dB and 2 dB, respectively. Hence, the generated wavelengths of 1st left and right order of FWM can be tuned in a range from ~1500 nm to ~1525 nm and ~1590 nm to ~1604 nm, respectively.

  18. Same sex families and children

    Directory of Open Access Journals (Sweden)

    Mršević Zorica

    2009-01-01

    Full Text Available Introduction comprises the information on two main forms of same sex families, civic partnership (same sex partnership and same sex marriage. Countries and various status modalities of legal regulations are mentioned. The main part of the text is dedicated to presentation of the findings of the most recent research on various aspects regarding children of same sex partnerships. It comprises presentations grouped in four main chapters: acceptance of same sex partnerships, acceptance of legal recognition of the same sex partnerships, family plans of homosexual teenagers, and raising children within and by the same sex partners. Also the real life cases mirroring legal changes through their life destinies are presented, such is e.g. the Irish way to legalization of the same sex partnerships. In addition, a love story of two women crowned by giving birth of their four children is mentioned. Reasons against and negative reactions the author puts under the title Homophobia. In the Concluding remarks, the author presents the most recent examples of legal changes happened in Norway, Ecuador, and in the American states of California and Connecticut. It was also stated that in European countries of low birth rate, the same sex families are inevitably identified as one of demographically valuable source of creating and raising children, which is worthy to be supported, rather than being hindered without reason and discriminated. Although different than a model of heterosexual family, same sex partnerships neither are harrowing to traditional family values, nor reflex of any kind of promiscuous, antisocial behavior, avoidance of parenthood, and negation of family. Quite opposite, these families are an outcome of endeavors of homosexuals not to be deprived of family, parenthood and all of other values of stabile, monogamous, emotional/sexual socially accepted and legally recognized and regulated conventional family. .

  19. Structure and thermal performance of poly(styrene-co-maleic anhydride)-g-alkyl alcohol comb-like copolymeric phase change materials

    International Nuclear Information System (INIS)

    Wang, Haixia; Shi, Haifeng; Qi, Miao; Zhang, Lingjian; Zhang, Xingxiang; Qi, Lu

    2013-01-01

    Graphical abstract: SMA-g-CnOH comb-like PCMs exhibit the better thermal stability against 1-alcohols due to the protection of SMA backbones, and the degradation temperature is dependent on the side-chain length, where at 5 wt% weight loss T d increased from 193 to 257 °C with n changing from 14 to 26. SMA-g-CnOH PCMs can be widely used under 300 °C for preparation of energy-saving products and materials. - Highlights: • The length of alkyl side-chains determines the thermal energy storage ability. • SMA backbone restricts the crystallization of alkyl side groups. • SMA-g-CnOH PCMs have the better thermal stability against 1-alcohols. - Abstract: A series of comb-like copolymeric phase change materials (SMA-g-CnOH) composed of poly(styrene-co-maleic anhydride) (SMA) and 1-alcohols CnOH with n = 14, 16, 18 or 26, respectively, was synthesized through grafting reaction. The structure and thermal properties of SMA-g-CnOH were investigated by 1 H nuclear magnetic resonance ( 1 H NMR), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD). The DSC analysis indicates that SMA-g-CnOH exhibit good structure stability with phase change enthalpies changing from 37.9 to 110.7 J g −1 . The results showed that the low thermal efficiency of SMA-g-CnOH was ascribed to the small CH 2 segments of side chains participating in the assembled structure of side-chain crystallites. Their advantageous structural stability and thermal performance of SMA-g-CnOH were favorable for phase change materials in the thermal energy storage systems. Additionally, the influence of side-chain length on thermal properties of SMA-g-CnOH also was discussed in detail in combination with the published results

  20. Reclassification of Geobacillus pallidus (Scholz et al. 1988) Banat et al. 2004 as Aeribacillus pallidus gen. nov., comb. nov.

    Science.gov (United States)

    Miñana-Galbis, David; Pinzón, Dora L; Lorén, J Gaspar; Manresa, Angels; Oliart-Ros, Rosa M

    2010-07-01

    Although Anoxybacillus and Geobacillus, two genera of thermophilic bacteria close to the genus Bacillus, have only been described recently, the number of species in these genera has increased rapidly. Four thermophilic, lipolytic strains (DR01, DR02, DR03 and DR04) isolated from a hot spring in Veracruz (Mexico), which could not be identified phenotypically, were subjected to 16S rRNA gene sequence analysis. Three strains were identified as belonging to the genus Anoxybacillus, but strain DR03 was identified as Geobacillus pallidus. This result led us to perform a phylogenetic analysis of the genera Anoxybacillus and Geobacillus based on 16S rRNA gene sequences from all the type strains of these genera. Phylogenetic trees showed three major clusters, Anoxybacillus-Geobacillus tepidamans, Geobacillus sensu stricto and Geobacillus pallidus, while the 16S rRNA gene sequences of G. pallidus (DR03 and the type strain) showed low similarity to sequences of Anoxybacillus (92.5-95.1 %) and Geobacillus (92.8-94.5 %) species, as well as to Bacillus subtilis (92.2-92.4 %). In addition, G. pallidus could be differentiated from Anoxybacillus and Geobacillus on the basis of DNA G+C content and fatty acid and polar lipid profiles. From these results, it is proposed that Geobacillus pallidus should be classified in a novel genus, for which we propose the name Aeribacillus, as Aeribacillus pallidus gen. nov., comb. nov. The type strain of Aeribacillus pallidus is H12(T) (=ATCC 51176(T) =DSM 3670(T) =LMG 19006(T)).

  1. Sex-linked dominant

    Science.gov (United States)

    Inheritance - sex-linked dominant; Genetics - sex-linked dominant; X-linked dominant; Y-linked dominant ... can be either an autosomal chromosome or a sex chromosome. It also depends on whether the trait ...

  2. Multiple sex partner

    African Journals Online (AJOL)

    User

    intercourse, about 60% reported having a single sexual partner and 40% reported having multiple ... masturbation, start having sex at a younger age, have sex with married people and/or .... sex were considered unacceptable by 89 vs.

  3. Development of a Flexible Broadband Rayleigh Waves Comb Transducer with Nonequidistant Comb Interval for Defect Detection of Thick-Walled Pipelines.

    Science.gov (United States)

    Zhao, Huamin; He, Cunfu; Yan, Lyu; Zhang, Haijun

    2018-03-02

    It is necessary to develop a transducer that can quickly detect the inner and outer wall defects of thick-walled pipes, in order to ensure the safety of such pipes. In this paper, a flexible broadband Rayleigh-waves comb transducer based on PZT (lead zirconate titanate) for defect detection of thick-walled pipes is studied. The multiple resonant coupling theory is used to expand the transducer broadband and the FEA (Finite Element Analysis) method is used to optimize transducer array element parameters. Optimization results show that the best array element parameters of the transducer are when the transducer array element length is 30 mm, the thickness is 1.2 mm, the width of one end of is 1.5 mm, and the other end is 3 mm. Based on the optimization results, such a transducer was fabricated and its performance was tested. The test results were consistent with the finite-element simulation results, and the -3 dB bandwidth of the transducer reached 417 kHz. Transducer directivity test results show that the Θ -3dB beam width was equal to 10 °, to meet the defect detection requirements. Finally, defects of thick-walled pipes were detected using the transducer. The results showed that the transducer could detect the inner and outer wall defects of thick-walled pipes within the bandwidth.

  4. Sex differences, gender and addiction.

    Science.gov (United States)

    Becker, Jill B; McClellan, Michele L; Reed, Beth Glover

    2017-01-02

    This review discusses alcohol and other forms of drug addiction as both a sociocultural and biological phenomenon. Sex differences and gender are not solely determined by biology, nor are they entirely sociocultural. The interactions among biological, environmental, sociocultural, and developmental influences result in phenotypes that may be more masculine or more feminine. These gender-related sex differences in the brain can influence the responses to drugs of abuse, progressive changes in the brain after exposure to drugs of abuse and whether addiction results from drug-taking experiences. In addition, the basic laboratory evidence for sex differences is discussed within the context of four types of sex/gender differences. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  5. Surface modification of cadmium sulfide thin film honey comb nanostructures: Effect of in situ tin doping using chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, K.C., E-mail: wilsonphy@gmail.com [Department of Physics, Govt. Polytechnic College Kothamangalam, Chelad P O, Ernakulam, Kerala 686681 (India); Department of Physics, B. S. Abdur Rahman University, Vandaloor, Chennai, Tamilnadu 600048 (India); Basheer Ahamed, M. [Department of Physics, B. S. Abdur Rahman University, Vandaloor, Chennai, Tamilnadu 600048 (India)

    2016-01-15

    Graphical abstract: - Highlights: • Novel honey comb like cadmium sulfide thin film nanostructures prepared using chemical bath deposition on glass substrates. • Honey comb nanostructure found in two layers: an ultra thin film at bottom and well inter connected with walls of < 25 nm thick on top; hence maximum surface area possible for CdS nanostructure. • Shell size of the nanostructures and energy band gaps were controlled also an enhanced persistent conductivity observed on Sn doping. - Abstract: Even though nanostructures possess large surface to volume ratio compared to their thin film counterpart, the complicated procedure that demands for the deposition on a substrate kept them back foot in device fabrication techniques. In this work, a honey comb like cadmium sulfide (CdS) thin films nanostructure are deposited on glass substrates using simple chemical bath deposition technique at 65 °C. Energy band gaps, film thickness and shell size of the honey comb nanostructures are successfully controlled using tin (Sn) doping and number of shells per unit area is found to be maximum for 5% Sn doped (in the reaction mixture) sample. X-ray diffraction and optical absorption analysis showed that cadmium sulfide and cadmium hydroxide coexist in the samples. TEM measurements showed that CdS nanostructures are embedded in cadmium hydroxide just like “plum pudding”. Persistent photoconductivity measurements of the samples are also carried out. The decay constants found to be increased with increases in Sn doping.

  6. Absolute spectroscopy near 7.8 {\\mu} m with a comb-locked extended-cavity quantum-cascade-laser

    KAUST Repository

    Lamperti, Marco; Alsaif, Bidoor; Gatti, Davide; Fermann, Martin; Laporta, Paolo; Farooq, Aamir; Marangoni, Marco

    2017-01-01

    We report the first experimental demonstration of frequency-locking of an extended-cavity quantum-cascade-laser (EC-QCL) to a near-infrared frequency comb. The locking scheme is applied to carry out absolute spectroscopy of N2O lines near 7.87 {\\mu

  7. Broadband optical frequency comb generator based on driving N-cascaded modulators by Gaussian-shaped waveform

    Science.gov (United States)

    Hmood, Jassim K.; Harun, Sulaiman W.

    2018-05-01

    A new approach for realizing a wideband optical frequency comb (OFC) generator based on driving cascaded modulators by a Gaussian-shaped waveform, is proposed and numerically demonstrated. The setup includes N-cascaded MZMs, a single Gaussian-shaped waveform generator, and N-1 electrical time delayer. The first MZM is driven directly by a Gaussian-shaped waveform, while delayed replicas of the Gaussian-shaped waveform drive the other MZMs. An analytical model that describes the proposed OFC generator is provided to study the effect of number and chirp factor of cascaded MZM as well as pulse width on output spectrum. Optical frequency combs at frequency spacing of 1 GHz are generated by applying Gaussian-shaped waveform at pulse widths ranging from 200 to 400 ps. Our results reveal that, the number of comb lines is inversely proportional to the pulse width and directly proportional to both number and chirp factor of cascaded MZMs. At pulse width of 200 ps and chirp factor of 4, 67 frequency lines can be measured at output spectrum of two-cascaded MZMs setup. Whereas, increasing the number of cascaded stages to 3, 4, and 5, the optical spectra counts 89, 109 and 123 frequency lines; respectively. When the delay time is optimized, 61 comb lines can be achieved with power fluctuations of less than 1 dB for five-cascaded MZMs setup.

  8. 75 FR 11559 - Certain Combed Cotton Yarns: Effect of Modification of U.S.-Bahrain FTA Rules of Origin

    Science.gov (United States)

    2010-03-11

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. Bahrain-FTA-103-025] Certain Combed Cotton Yarns: Effect of Modification of U.S.- Bahrain FTA Rules of Origin AGENCY: United States International Trade... to section 104 of the United States-Bahrain Free Trade Agreement (FTA) Implementation Act (19 U.S.C...

  9. New ends to the tale of tails: adsorption of comb polymers and the effect on colloid stability

    NARCIS (Netherlands)

    Charlaganov, M.; Kosovan, P.; Leermakers, F.A.M.

    2009-01-01

    In this paper we consider the classical problem of homopolymer adsorption at the solid–liquid interface and discuss its implications for colloidal stability. More specifically, our focus is on comb-like homopolymers in the strong adsorption limit. A self-consistent field analysis shows that for

  10. Comparative flight activities and pathogen load of two stocks of honey bees reared in gamma-irradiated combs

    Science.gov (United States)

    Gamma irradiation is known to inactivate various pathogens that negatively affect honey bee health. Bee pathogens such as Deformed wing virus (DWV) and Nosema spp. have deleterious impact on foraging activities and bee survival, and have been detected in combs. In this study, we assessed the effects...

  11. Sex differences in heritability of BMI

    DEFF Research Database (Denmark)

    Schousboe, Karoline; Willemsen, Gonneke; Kyvik, Kirsten O

    2003-01-01

    pairs (including opposite sex pairs) aged 20-29 and 30-39 from eight different twin registries participating in the GenomEUtwin project. Quantitative genetic analyses were conducted and sex differences were explored. Variation in BMI was greater for women than for men, and in both sexes was primarily...... explained by additive genetic variance in all countries. Sex differences in the variance components were consistently significant. Results from analyses of opposite sex pairs also showed evidence of sex-specific genetic effects suggesting there may be some differences between men and women in the genetic...... factors that influence variation in BMI. These results encourage the continued search for genes of importance to the body composition and the development of obesity. Furthermore, they suggest that strategies to identify predisposing genes may benefit from taking into account potential sex specific effects....

  12. Stable optical frequency comb generation and applications in arbitrary waveform generation, signal processing and optical data mining

    Science.gov (United States)

    Ozharar, Sarper

    This thesis focuses on the generation and applications of stable optical frequency combs. Optical frequency combs are defined as equally spaced optical frequencies with a fixed phase relation among themselves. The conventional source of optical frequency combs is the optical spectrum of the modelocked lasers. In this work, we investigated alternative methods for optical comb generation, such as dual sine wave phase modulation, which is more practical and cost effective compared to modelocked lasers stabilized to a reference. Incorporating these comblines, we have generated tunable RF tones using the serrodyne technique. The tuning range was +/-1 MHz, limited by the electronic waveform generator, and the RF carrier frequency is limited by the bandwidth of the photodetector. Similarly, using parabolic phase modulation together with time division multiplexing, RF chirp extension has been realized. Another application of the optical frequency combs studied in this thesis is real time data mining in a bit stream. A novel optoelectronic logic gate has been developed for this application and used to detect an 8 bit long target pattern. Also another approach based on orthogonal Hadamard codes have been proposed and explained in detail. Also novel intracavity modulation schemes have been investigated and applied for various applications such as (a) improving rational harmonic modelocking for repetition rate multiplication and pulse to pulse amplitude equalization, (b) frequency skewed pulse generation for ranging and (c) intracavity active phase modulation in amplitude modulated modelocked lasers for supermode noise spur suppression and integrated jitter reduction. The thesis concludes with comments on the future work and next steps to improve some of the results presented in this work.

  13. Understanding Sex for Sale

    DEFF Research Database (Denmark)

    This book Understanding Sex for Sale: Meanings and Moralities of Sexual Commerce is dedicated to the exploration of the ways in which sex prostitution, sex work or sex for sale are taken for granted by particularly looking at how the relation between sex and money is interpreted and enacted....... This interdisciplinary book aims to understand how prostitution, sex work or sex for sale are defined, delineated, contested and understood in different places and times. The book offers contributions from a number of scholars who, based on their on their own research, discuss on going theoretical issues and analytical...... challenges Some chapters focuses on how prostitution, sex work or sex for sale have been regulated by the authorities and what understandings this regulation builds on. Other chapters investigate the experiences of the sex workers and sex buyers asking how these actors adjust to or resist the categorisation...

  14. Advanced RF and microwave functions based on an integrated optical frequency comb source.

    Science.gov (United States)

    Xu, Xingyuan; Wu, Jiayang; Nguyen, Thach G; Shoeiby, Mehrdad; Chu, Sai T; Little, Brent E; Morandotti, Roberto; Mitchell, Arnan; Moss, David J

    2018-02-05

    We demonstrate advanced transversal radio frequency (RF) and microwave functions based on a Kerr optical comb source generated by an integrated micro-ring resonator. We achieve extremely high performance for an optical true time delay aimed at tunable phased array antenna applications, as well as reconfigurable microwave photonic filters. Our results agree well with theory. We show that our true time delay would yield a phased array antenna with features that include high angular resolution and a wide range of beam steering angles, while the microwave photonic filters feature high Q factors, wideband tunability, and highly reconfigurable filtering shapes. These results show that our approach is a competitive solution to implementing reconfigurable, high performance and potentially low cost RF and microwave signal processing functions for applications including radar and communication systems.

  15. A novel technique for one-dimensional scattering from Dirac Comb

    International Nuclear Information System (INIS)

    Taya, Sofyan A.; Shabat, M.M.

    2001-08-01

    Using the well-known matrix formulation of the reflection and transmission of electromagnetic waves by a stratified planner structure, we show that the reflection and transmission coefficients of any number of isotropic media can be written by a simple general formula. This formula uses the so-called elementary symmetric functions that are extensively used in the mathematical theory of polynomials. The approach is then applied to the quantum scattering. We show that the reflection and transmission coefficients of any number of quantum wells or barriers can be written in the similar way. Finally, one-dimensional scattering from a series of delta-function barriers (a system that is called Dirac Comb) is studied. The computed numerical illustrations compared with the earlier results based on the transfer matrix and Chebychev polynomials reveal an excellent agreement. (author)

  16. Vector frequency-comb Fourier-transform spectroscopy for characterizing metamaterials

    International Nuclear Information System (INIS)

    Ganz, T; Brehm, M; Von Ribbeck, H G; Keilmann, F; Van der Weide, D W

    2008-01-01

    We determine infrared transmission amplitude and phase spectra of metamaterial samples at well-defined incidence and polarization with a vector ('asymmetric') frequency-comb Fourier-transform spectrometer (c-FTS) that uses no moving elements. The metamaterials are free-standing metallic hole arrays; we study their resonances in the 7-13 μm and 100-1000 μm wavelength regions due both to interaction with bulk waves (Wood anomaly) and with leaky surface plasmon polaritons (near-unity transmittance, coupling features and dispersion). Such complex-valued transmission and reflection spectra could be used to compute a metamaterial's complex dielectric function directly, as well as its magnetic and magneto-optical permeability functions.

  17. Noncritical generation of nonclassical frequency combs via spontaneous rotational symmetry breaking

    Science.gov (United States)

    Navarrete-Benlloch, Carlos; Patera, Giuseppe; de Valcárcel, Germán J.

    2017-10-01

    Synchronously pumped optical parametric oscillators (SPOPOs) are optical cavities driven by mode-locked lasers, and containing a nonlinear crystal capable of down-converting a frequency comb to lower frequencies. SPOPOs have received a lot of attention lately because their intrinsic multimode nature makes them compact sources of quantum correlated light with promising applications in modern quantum information technologies. In this work we show that SPOPOs are also capable of accessing the challenging and interesting regime where spontaneous symmetry breaking confers strong nonclassical properties to the emitted light, which has eluded experimental observation so far. Apart from opening the possibility of studying experimentally this elusive regime of dissipative phase transitions, our predictions will have a practical impact, since we show that spontaneous symmetry breaking provides a specific spatiotemporal mode with large quadrature squeezing for any value of the system parameters, turning SPOPOs into robust sources of highly nonclassical light above threshold.

  18. Dual Comb Unit High-g Accelerometer Based on CMOS-MEMS Technology

    Directory of Open Access Journals (Sweden)

    Mehrdad Mottaghi

    2009-04-01

    Full Text Available In this paper a capacitive based high-g accelerometer with superior level of sensitivity is presented. It takes advantage of dual comb unit configuration and surface micromachining fabrication process. All aspects of mechanical design such as sensor structure, modal analysis, energy dissipations, dynamic response and stresses in moving structure as well as anchors are described. Electrical circuit based on CMOS technology and its output signal is presented. Fabrication process and packaging are also discussed. The proposed sensor can endure impact loads up to 120,000 g (g = 9.81 m.s-2 and achieves 16.75 µV.g-1 sensitivity with 5 V bridge excitation voltage. Main resonant frequency of structure is found to be 42.4 kHz. Intended applications of suggested sensor include military and aerospace industries as well as field of impact engineering.

  19. Coherent storage of temporally multimode light using a spin-wave atomic frequency comb memory

    International Nuclear Information System (INIS)

    Gündoğan, M; Mazzera, M; Ledingham, P M; Cristiani, M; De Riedmatten, H

    2013-01-01

    We report on the coherent and multi-temporal mode storage of light using the full atomic frequency comb memory scheme. The scheme involves the transfer of optical atomic excitations in Pr 3+ :Y 2 SiO 5 to spin waves in hyperfine levels using strong single-frequency transfer pulses. Using this scheme, a total of five temporal modes are stored and recalled on-demand from the memory. The coherence of the storage and retrieval is characterized using a time-bin interference measurement resulting in visibilities higher than 80%, independent of the storage time. This coherent and multimode spin-wave memory is promising as a quantum memory for light. (paper)

  20. Fibre optics wavemeters calibration using a self-referenced optical frequency comb

    Energy Technology Data Exchange (ETDEWEB)

    Galindo-Santos, J.; Velasco, A. V.; Corredera, P. [Instituto de Óptica IO-CSIC, C/Serrano 121, 28006 Madrid (Spain)

    2015-01-15

    Self-referenced optical frequency combs enable the measurement of optical frequencies with a very high accuracy, achieving uncertainties close to the atomic clock used as reference (<10{sup −13} s). In this paper, we present the technique for the measurement of laser frequencies for optical communications followed at IO-CSIC and its application to the calibration of two wavemeters in the 1.5 μm optical communication window. Calibration uncertainties down to 12 MHz and 59 MHz were obtained, respectively, for each of the devices. Furthermore, the long-term behaviour of the higher resolution wavemeter was studied during a 750 h period of sustained operation, exhibiting a dispersion in the measurements of 7.72 MHz. Temperature dependence of the device was analysed, enabling to further reduce dispersion down to a 2.15 MHz range, with no significant temporal deviations.

  1. Deuterated silicon nitride photonic devices for broadband optical frequency comb generation

    Science.gov (United States)

    Chiles, Jeff; Nader, Nima; Hickstein, Daniel D.; Yu, Su Peng; Briles, Travis Crain; Carlson, David; Jung, Hojoong; Shainline, Jeffrey M.; Diddams, Scott; Papp, Scott B.; Nam, Sae Woo; Mirin, Richard P.

    2018-04-01

    We report and characterize low-temperature, plasma-deposited deuterated silicon nitride thin films for nonlinear integrated photonics. With a peak processing temperature less than 300$^\\circ$C, it is back-end compatible with pre-processed CMOS substrates. We achieve microresonators with a quality factor of up to $1.6\\times 10^6 $ at 1552 nm, and $>1.2\\times 10^6$ throughout $\\lambda$ = 1510 -- 1600 nm, without annealing or stress management. We then demonstrate the immediate utility of this platform in nonlinear photonics by generating a 1 THz free spectral range, 900-nm-bandwidth modulation-instability microresonator Kerr comb and octave-spanning, supercontinuum-broadened spectra.

  2. Dynamics of Peregrine combs and Peregrine walls in an inhomogeneous Hirota and Maxwell-Bloch system

    Science.gov (United States)

    Wang, Lei; Wang, Zi-Qi; Sun, Wen-Rong; Shi, Yu-Ying; Li, Min; Xu, Min

    2017-06-01

    Under investigation in this paper is an inhomogeneous Hirota-Maxwell-Bloch (IHMB) system which can describe the propagation of optical solitons in an erbium-doped optical fiber. The breather multiple births (BMBs) are derived with periodically varying group velocity dispersion (GVD) coefficients. Under large periodic modulations in the GVD coefficient of IHMB system, the Peregrine comb (PC) solution is produced, which can be viewed as the limiting case of the BMBs. When the amplitude of the modulation satisfies a special condition, the Peregrine wall (PW) that can be regarded as an intermediate state between rogue wave and PC is obtained. The effects of the third-order dispersion on the spatiotemporal characteristics of PCs and PWs are studied. Our results may be useful for the experimental control and manipulation of the formation of generalized Peregrine rogue waves in inhomogeneous erbium-doped optical fiber.

  3. Quantum logic for the control and manipulation of molecular ions using a frequency comb

    International Nuclear Information System (INIS)

    Ding, S; Matsukevich, D N

    2012-01-01

    We propose a scheme for the preparation, manipulation and detection of quantum states of single molecular ions. In this scheme, molecular and atomic ions are confined in radio-frequency Paul trap and share common modes of motion. A frequency comb laser field is used to drive stimulated Raman transitions that couple internal states of the molecular ion with the motion of ions. State transfer from the molecular ion to the atomic ion via the common mode of motion results in efficient state detection for the molecule. The coupling of molecular states to the motion and the subsequent sideband cooling of the ions provide a way to prepare the molecular ion in a well-defined state. (paper)

  4. Finite Element Analysis of the Vertical Levitation Force in an Electrostatic MEMS Comb Drive Actuator

    International Nuclear Information System (INIS)

    Wooldridge, J; Blackburn, J; Muniz-Piniella, A; Stewart, M; Shean, T A V; Weaver, P M; Cain, M G

    2013-01-01

    A vertical levitation electrostatic comb drive actuator was manufactured for the purpose of measuring piezoelectric coefficients in small-scale materials and devices. Previous modelling work on comb drive levitation has focussed on control of the levitation in standard poly-silicon devices in order to minimize effects on lateral modes of operation required for the accelerometer and gyroscope applications. The actuator developed in this study was manufactured using a 20 μm electroplated Ni process with a 25 μm trench created beneath the released structure through chemical wet etching. A finite element analysis using ZINC was used to model electrostatic potential around a cross section of one static and one movable electrode, from which the net levitation force per unit electrode was calculated. The model was first verified using the electrode geometry from previously studied systems, and then used to study the variation of force as a function of decreasing substrate-electrode distance. With the top electrode surfaces collinear the calculated force density is 0.00651 ε 0 V 2 M μm −1 , equivalent to a total force for the device of 36.4 μN at an applied voltage of V M =100 V, just 16% larger than the observed value. The measured increase in force with distance was smaller than predicted with the FEA, due to the geometry of the device in which the electrodes at the anchored ends of the supporting spring structure displace by a smaller amount than those at the centre

  5. Sex differences in the brain-an interplay of sex steroid hormones and sex chromosomes.

    Science.gov (United States)

    Grgurevic, Neza; Majdic, Gregor

    2016-09-01

    Although considerable progress has been made in our understanding of brain function, many questions remain unanswered. The ultimate goal of studying the brain is to understand the connection between brain structure and function and behavioural outcomes. Since sex differences in brain morphology were first observed, subsequent studies suggest different functional organization of the male and female brains in humans. Sex and gender have been identified as being a significant factor in understanding human physiology, health and disease, and the biological differences between the sexes is not limited to the gonads and secondary sexual characteristics, but also affects the structure and, more crucially, the function of the brain and other organs. Significant variability in brain structures between individuals, in addition to between the sexes, is factor that complicates the study of sex differences in the brain. In this review, we explore the current understanding of sex differences in the brain, mostly focusing on preclinical animal studies. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

  6. Influence of the nematic order on the rheology and conformation of stretched comb-like liquid crystalline polymers

    Science.gov (United States)

    Fourmaux-Demange, V.; Brûlet, A.; Boué, F.; Davidson, P.; Keller, P.; Cotton, J. P.

    2000-04-01

    We have studied the rheology and the conformation of stretched comb-like liquid-crystalline polymers. Both the influence of the comb-like structure and the specific effect of the nematic interaction on the dynamics are investigated. For this purpose, two isomers of a comb-like polymetacrylate polymer, of well-defined molecular weights, were synthesized: one displays a nematic phase over a wide range of temperature, the other one has only an isotropic phase. Even with high degrees of polymerization N, between 40 and 1000, the polymer chains studied were not entangled. The stress-strain curves during the stretching and relaxation processes show differences between the isotropic and nematic comb-like polymers. They suggest that, in the nematic phase, the chain dynamics is more cooperative than for a usual linear polymer. Small-angle neutron scattering has been used in order to determine the evolution of the chain conformation after stretching, as a function of the duration of relaxation t_r. The conformation can be described with two parameters only: λ_p, the global deformation of the polymer chain, and p, the number of statistical units of locally relaxed sub-chains. For the comb-like polymer, the chain deformation is pseudo-affine: λ_p is always smaller than λ (the deformation ratio of the whole sample). In the isotropic phase, λ_p has a constant value, while p increases as t_r. This latter behavior is not that expected for non-entangled chains, in which p varies as {t_r}^{1/2} (Rouse model). In the nematic phase, λ_p decreases as a stretched exponential function of t_r, while p remains constant. The dynamics of the comb-like polymers is discussed in terms of living clusters from which junctions are produced by interactions between side chains. The nematic interaction increases the lifetime of these junctions and, strikingly, the relaxation is the same at all scales of the whole polymer chain.

  7. Pilotstudie naar welzijnsaspecten van kammen dubben bij hanen van legrassen = Pilot study welfare implications of dubbing combs of cockerels of Leghorn parent stock

    NARCIS (Netherlands)

    Niekerk, van T.G.C.M.; Gunnink, H.; Reuvekamp, B.F.J.

    2011-01-01

    In a small pilot experiment the impact of comb dubbing on male chicks has been investigated. No effect on behaviour, growth and feed intake was recorded, suggesting that dubbing has no major effect on welfare of the chicks.

  8. Reclassification of Flexibacter tractuosus (Lewin 1969) Leadbetter 1974 and 'Microscilla sericea' Lewin 1969 in the genus Marivirga gen. nov. as Marivirga tractuosa comb. nov. and Marivirga sericea nom. rev., comb. nov.

    Science.gov (United States)

    Nedashkovskaya, Olga I; Vancanneyt, Marc; Kim, Seung Bum; Bae, Kyung Sook

    2010-08-01

    The taxonomic position of the misclassified strains [Flexibacter] tractuosus KCTC 2958T and '[Microscilla] sericea' LMG 13021 was studied using a polyphasic approach. The two strains shared 99.1% 16S rRNA gene sequence similarity and 28% DNA-DNA relatedness. On the basis of the phylogenetic evidence supported by genotypic and phenotypic data [Flexibacter] tractuosus KCTC 2958T and '[Microscilla] sericea' LMG 13021 are classified as two distinct species in a novel genus, Marivirga, in the family 'Flammeovirgaceae', as Marivirga tractuosa comb. nov. and Marivirga sericea nom. rev., comb. nov., with strains KCTC 2958T (=ATCC 23168T =CIP 106410T =DSM 4126T =NBRC 15989T =NCIMB 1408T =VKM B-1430T) and LMG 13021T (=ATCC 23182T =NBRC 15983T =NCIMB 1403T), respectively, as the type strains. The type species is Marivirga tractuosa.

  9. Classification of heparinolytic bacteria into a new genus, Pedobacter, comprising four species: Pedobacter heparinus comb. nov., Pedobacter piscium comb. nov., Pedobacter africanus sp. nov. and Pedobacter saltans sp. nov. proposal of the family Sphingobacteriaceae fam. nov.

    Science.gov (United States)

    Steyn, P L; Segers, P; Vancanneyt, M; Sandra, P; Kersters, K; Joubert, J J

    1998-01-01

    Sixteen heparinase-producing isolates, related to Sphingobacterium heparinum, were grouped into three major clusters by SDS-PAGE and DNA-rRNA hybridizations. Based on a polyphasic approach, it was shown that isolates of two of these clusters and S. heparinum species belong to a new genus for which the name Pedobacter is proposed. The genus consists of Pedobacter heparinus comb. nov. (formerly Sphingobacterium heparinum), which is the type species, Pedobacter piscium comb. nov. (formerly Sphingobacterium piscium), Pedobacter africanus sp. nov. and Pedobacter saltans sp. nov. and four as-yet-unnamed DNA hybridization groups. All the previously named taxa can be discriminated by phenotypic features, but have strong overall similarities with representatives of the genus Sphingobacterium and the misclassified species [Flexibacter] canadensis. All these organisms constitute a separate rRNA branch in rRNA superfamily V for which the family Sphingobacteriaceae fam. nov. is proposed.

  10. Did Lizards Follow Unique Pathways in Sex Chromosome Evolution?

    Science.gov (United States)

    Gleeson, Dianne; Georges, Arthur

    2018-01-01

    Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD) and temperature-dependent sex determination (TSD) within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata) which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways. PMID:29751579

  11. Did Lizards Follow Unique Pathways in Sex Chromosome Evolution?

    Directory of Open Access Journals (Sweden)

    Shayer Mahmood Ibney Alam

    2018-05-01

    Full Text Available Reptiles show remarkable diversity in modes of reproduction and sex determination, including high variation in the morphology of sex chromosomes, ranging from homomorphic to highly heteromorphic. Additionally, the co-existence of genotypic sex determination (GSD and temperature-dependent sex determination (TSD within and among sister clades makes this group an attractive model to study and understand the evolution of sex chromosomes. This is particularly so with Lizards (Order Squamata which, among reptiles, show extraordinary morphological diversity. They also show no particular pattern of sex chromosome degeneration of the kind observed in mammals, birds and or even in snakes. We therefore speculate that sex determination sensu sex chromosome evolution is labile and rapid and largely follows independent trajectories within lizards. Here, we review the current knowledge on the evolution of sex chromosomes in lizards and discuss how sex chromosome evolution within that group differs from other amniote taxa, facilitating unique evolutionary pathways.

  12. Frequency-comb-assisted precision laser spectroscopy of CHF{sub 3} around 8.6 μm

    Energy Technology Data Exchange (ETDEWEB)

    Gambetta, Alessio; Coluccelli, Nicola; Cassinerio, Marco; Fernandez, Toney Teddy; Gatti, Davide; Laporta, Paolo; Galzerano, Gianluca, E-mail: gianluca.galzerano@polimi.it [Dipartimento di Fisica - Politecnico di Milano and Istituto di Fotonica e Nanotecnologie - CNR, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Castrillo, Antonio; Fasci, Eugenio; Gianfrani, Livio [Dipartimento di Matematica e Fisica - Seconda Università di Napoli, Viale Lincoln 5, 81100 Caserta (Italy); Ceausu-Velcescu, Adina [Laboratoire de Mathématiques et Physique, Université de Perpignan, Via Domitia EA 4217, F-66860 Perpignan (France); Santamaria, Luigi; Di Sarno, Valentina [CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, NA (Italy); Maddaloni, Pasquale [CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, NA (Italy); INFN, Istituto Nazionale di Fisica Nucleare, Sez. Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, FI (Italy); De Natale, Paolo [INFN, Istituto Nazionale di Fisica Nucleare, Sez. Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, FI (Italy); CNR-INO, Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze (Italy)

    2015-12-21

    We report a high-precision spectroscopic study of room-temperature trifluoromethane around 8.6 μm, using a CW quantum cascade laser phase-locked to a mid-infrared optical frequency comb. This latter is generated by a nonlinear down-conversion process starting from a dual-branch Er:fiber laser and is stabilized against a GPS-disciplined rubidium clock. By tuning the comb repetition frequency, several transitions falling in the υ{sub 5} vibrational band are recorded with a frequency resolution of 20 kHz. Due to the very dense spectra, a special multiple-line fitting code, involving a Voigt profile, is developed for data analysis. The combination of the adopted experimental approach and survey procedure leads to fractional accuracy levels in the determination of line center frequencies, down to 2 × 10{sup −10}. Line intensity factors, pressure broadening, and shifting parameters are also provided.

  13. 18-THz-wide optical frequency comb emitted from monolithic passively mode-locked semiconductor quantum-well laser

    Science.gov (United States)

    Lo, Mu-Chieh; Guzmán, Robinson; Ali, Muhsin; Santos, Rui; Augustin, Luc; Carpintero, Guillermo

    2017-10-01

    We report on an optical frequency comb with 14nm (~1.8 THz) spectral bandwidth at -3 dB level that is generated using a passively mode-locked quantum-well (QW) laser in photonic integrated circuits (PICs) fabricated through an InP generic photonic integration technology platform. This 21.5-GHz colliding-pulse mode-locked laser cavity is defined by on-chip reflectors incorporating intracavity phase modulators followed by an extra-cavity SOA as booster amplifier. A 1.8-THz-wide optical comb spectrum is presented with ultrafast pulse that is 0.35-ps-wide. The radio frequency beat note has a 3-dB linewidth of 450 kHz and 35-dB SNR.

  14. Two-crystal mid-infrared optical parametric oscillator for absorption and dispersion dual-comb spectroscopy.

    Science.gov (United States)

    Jin, Yuwei; Cristescu, Simona M; Harren, Frans J M; Mandon, Julien

    2014-06-01

    We present a femtosecond optical parametric oscillator (OPO) containing two magnesium-doped periodically poled lithium niobate crystals in a singly resonant ring cavity, pumped by two mode-locked Yb-fiber lasers. As such, the OPO generates two idler combs (up to 220 mW), covering a wavelength range from 2.7 to 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyning signal between the two idler beams a full broadband spectrum of a molecular gas can be observed over 250  cm(-1) within 70 μs with a spectral resolution of 15 GHz. The absorption and dispersion spectra of acetylene and methane have been measured around 3000  cm(-1), indicating that this OPO represents an ideal broadband mid-infrared source for fast chemical sensing.

  15. Coupled Lugiato-Lefever equation for nonlinear frequency comb generation at an avoided crossing of a microresonator

    Science.gov (United States)

    D'Aguanno, Giuseppe; Menyuk, Curtis R.

    2017-03-01

    Guided-mode coupling in a microresonator generally manifests itself through avoided crossings of the corresponding resonances. This coupling can strongly modify the resonator local effective dispersion by creating two branches that have dispersions of opposite sign in spectral regions that would otherwise be characterized by either positive (normal) or negative (anomalous) dispersion. In this paper, we study, both analytically and computationally, the general properties of nonlinear frequency comb generation at an avoided crossing using the coupled Lugiato-Lefever equation. In particular, we find that bright solitons and broadband frequency combs can be excited when both branches are pumped for a suitable choice of the pump powers and the detuning parameters. A deterministic path for soliton generation is found. Contribution to the Topical Issue "Theory and applications of the Lugiato-Lefever Equation", edited by Yanne K. Chembo, Damia Gomila, Mustapha Tlidi, Curtis R. Menyuk.

  16. Research on spectrum broadening covering visible light of a fiber femtosecond optical frequency comb for absolute frequency measurement

    Science.gov (United States)

    Xing, Shuai; Wu, Tengfei; Li, Shuyi; Xia, Chuanqing; Han, Jibo; Zhang, Lei; Zhao, Chunbo

    2018-03-01

    As a bridge connecting microwave frequency and optical frequency, femtosecond laser has important significance in optical frequency measurement. Compared with the traditional Ti-sapphire femtosecond optical frequency comb, with the advantages of compact structure, strong anti-interference ability and low cost, the fiber femtosecond optical frequency comb has a wider application prospect. An experiment of spectrum broadening in a highly nonlinear photonic crystal fiber pumped by an Er-fiber mode-locked femtosecond laser is studied in this paper. Based on optical amplification and frequency doubling, the central wavelength of the output spectrum is 780nm and the average power is 232mW. With the femtosecond pulses coupled into two different photonic crystal fibers, the coverage of visible spectrum is up to 500nm-960nm. The spectral shape and width can be optimized by changing the polarization state for satisfying the requirments of different optical frequencies measurement.

  17. Frequency locking of an extended-cavity quantum cascade laser to a frequency comb for precision mid infrared spectroscopy

    KAUST Repository

    Alsaif, Bidoor; Lamperti, Marco; Gatti, Davide; Laporta, Paolo; Fermann, Martin E.; Farooq, Aamir; Marangoni, Marco

    2017-01-01

    Extended-cavity quantum cascade lasers (EC-QCLs) enable mode-hope-free frequency sweeps in the mid-infrared region over ranges in excess of 100 cm−1, at speeds up to 1 THz/s and with a 100-mW optical power level. This makes them ideally suited for broadband absorption spectroscopy and for the simultaneous detection of multiple gases. On the other hand, their use for precision spectroscopy has been hampered so far by a large amount of frequency noise, resulting in an optical linewidth of about 30 MHz over 50 ms [1]. This is one of the reasons why neither their frequency nor their phase have been so far locked to a frequency comb. Their use in combination with frequency combs has been performed in an open loop regime only [2], which has the merit of preserving the inherently fast modulation speed of these lasers, yet not to afford high spectral resolution and accuracy.

  18. Real-Time and Meter-Scale Absolute Distance Measurement by Frequency-Comb-Referenced Multi-Wavelength Interferometry

    Directory of Open Access Journals (Sweden)

    Guochao Wang

    2018-02-01

    Full Text Available We report on a frequency-comb-referenced absolute interferometer which instantly measures long distance by integrating multi-wavelength interferometry with direct synthetic wavelength interferometry. The reported interferometer utilizes four different wavelengths, simultaneously calibrated to the frequency comb of a femtosecond laser, to implement subwavelength distance measurement, while direct synthetic wavelength interferometry is elaborately introduced by launching a fifth wavelength to extend a non-ambiguous range for meter-scale measurement. A linearity test performed comparatively with a He–Ne laser interferometer shows a residual error of less than 70.8 nm in peak-to-valley over a 3 m distance, and a 10 h distance comparison is demonstrated to gain fractional deviations of ~3 × 10−8 versus 3 m distance. Test results reveal that the presented absolute interferometer enables precise, stable, and long-term distance measurements and facilitates absolute positioning applications such as large-scale manufacturing and space missions.

  19. Real-Time and Meter-Scale Absolute Distance Measurement by Frequency-Comb-Referenced Multi-Wavelength Interferometry.

    Science.gov (United States)

    Wang, Guochao; Tan, Lilong; Yan, Shuhua

    2018-02-07

    We report on a frequency-comb-referenced absolute interferometer which instantly measures long distance by integrating multi-wavelength interferometry with direct synthetic wavelength interferometry. The reported interferometer utilizes four different wavelengths, simultaneously calibrated to the frequency comb of a femtosecond laser, to implement subwavelength distance measurement, while direct synthetic wavelength interferometry is elaborately introduced by launching a fifth wavelength to extend a non-ambiguous range for meter-scale measurement. A linearity test performed comparatively with a He-Ne laser interferometer shows a residual error of less than 70.8 nm in peak-to-valley over a 3 m distance, and a 10 h distance comparison is demonstrated to gain fractional deviations of ~3 × 10 -8 versus 3 m distance. Test results reveal that the presented absolute interferometer enables precise, stable, and long-term distance measurements and facilitates absolute positioning applications such as large-scale manufacturing and space missions.

  20. Frequency locking of an extended-cavity quantum cascade laser to a frequency comb for precision mid infrared spectroscopy

    KAUST Repository

    Alsaif, Bidoor

    2017-11-02

    Extended-cavity quantum cascade lasers (EC-QCLs) enable mode-hope-free frequency sweeps in the mid-infrared region over ranges in excess of 100 cm−1, at speeds up to 1 THz/s and with a 100-mW optical power level. This makes them ideally suited for broadband absorption spectroscopy and for the simultaneous detection of multiple gases. On the other hand, their use for precision spectroscopy has been hampered so far by a large amount of frequency noise, resulting in an optical linewidth of about 30 MHz over 50 ms [1]. This is one of the reasons why neither their frequency nor their phase have been so far locked to a frequency comb. Their use in combination with frequency combs has been performed in an open loop regime only [2], which has the merit of preserving the inherently fast modulation speed of these lasers, yet not to afford high spectral resolution and accuracy.

  1. Absolute spectroscopy near 7.8 {\\mu} m with a comb-locked extended-cavity quantum-cascade-laser

    KAUST Repository

    Lamperti, Marco

    2017-07-31

    We report the first experimental demonstration of frequency-locking of an extended-cavity quantum-cascade-laser (EC-QCL) to a near-infrared frequency comb. The locking scheme is applied to carry out absolute spectroscopy of N2O lines near 7.87 {\\\\mu}m with an accuracy of ~60 kHz. Thanks to a single mode operation over more than 100 cm^{-1}, the comb-locked EC-QCL shows great potential for the accurate retrieval of line center frequencies in a spectral region that is currently outside the reach of broadly tunable cw sources, either based on difference frequency generation or optical parametric oscillation. The approach described here can be straightforwardly extended up to 12 {\\\\mu}m, which is the current wavelength limit for commercial cw EC-QCLs.

  2. Sex reassignment surgery in Thailand.

    Science.gov (United States)

    Chokrungvaranont, Prayuth; Tiewtranon, Preecha

    2004-11-01

    Many years ago Thai society considered transsexualism (Gender identity disorder or Gender dysphoria) which is commonly known as Kathoey (a word originally used to denote hermaphrodites), Sao Prapet Song or Tut (as in 'Tootsie') were low class citizens, dirty dressing and had to hide in a dark corner selling their services as prostitutes. This made us unwilling to do sex reassignment surgery for this group of people because the idea of eradicating normal sexual organs for the purpose that was not accepted by the society. Consequently the authors have experience in cases where these people wandered seeking doctors who had no competency nor enough experience to do the surgery. The authors could not inhibit the desire of these people who usually suffer from gender identity disorder from strongly wishing to change their genital sex to the sex they want. The outcome of the surgery was not satisfactory for the patients. There were complications and sequelae which caused the authors to correct them later which might be more difficult than doing the original surgery. In addition there were more studies about the etiology and affect of the disorder on these people that changed the social point of view. The women who wanted to be a him and men who would like to be a her should be considered as patients who need to be cured to set the harmony about their genetic sex and the desire to be the opposite sex and also to be regarded by others as a member of that other sex. The treatments of transsexualism usually begin with conventional psychiatric and endocrinological treatment to adjust the mind to the body. For those who failed conservative treatment in adjusting the mind to the body then sex reassignment surgery will be the only way to transform their body to their mind and give the best result in properly selected patients. Preecha Tiewtranon, the pioneer in sex reassignment surgery in Thailand, did his transsexualism case in 1975 together with Dr. Prakob Thongpeaw. Sex

  3. Generation of picosecond pulses and frequency combs in actively mode locked external ring cavity quantum cascade lasers

    International Nuclear Information System (INIS)

    Wójcik, Aleksander K.; Belyanin, Alexey; Malara, Pietro; Blanchard, Romain; Mansuripur, Tobias S.; Capasso, Federico

    2013-01-01

    We propose a robust and reliable method of active mode locking of mid-infrared quantum cascade lasers and develop its theoretical description. Its key element is the use of an external ring cavity, which circumvents fundamental issues undermining the stability of mode locking in quantum cascade lasers. We show that active mode locking can give rise to the generation of picosecond pulses and phase-locked frequency combs containing thousands of the ring cavity modes

  4. A facile metal-free "grafting-from" route from acrylamide-based substrate toward complex macromolecular combs

    KAUST Repository

    Zhao, Junpeng

    2013-01-01

    High-molecular-weight poly(N,N-dimethylacrylamide-co-acrylamide) was used as a model functional substrate to investigate phosphazene base (t-BuP 4)-promoted metal-free anionic graft polymerization utilizing primary amide moieties as initiating sites. The (co)polymerization of epoxides was proven to be effective, leading to macromolecular combs with side chains being single- or double-graft homopolymer, block copolymer and statistical copolymer. © 2013 The Royal Society of Chemistry.

  5. Combined radioimmunoassay of HBs-antigen and anti-HBs using the Biotest combRIA-Au kit

    International Nuclear Information System (INIS)

    Kselikova, M.; Novak, J.; Urbankova, J.

    1979-01-01

    Hepatitis B antigen and antibody were determined simultaneously by radioimmunoassay using the Biotest combRIA-Au kit. The results in determining antigens and antibodies in sera with a known content of these substances by this kit nearly equal those of isolated determinations of antigen by the Abbott AUSRIA II-125 kit, and of antibody by the Abbott AUSAB kit, resp., except for a negligible number of sera with a very low content of either antigen or antibody. (author)

  6. Local behavioral rules sustain the cell allocation pattern in the combs of honey bee colonies (Apis mellifera).

    Science.gov (United States)

    Montovan, Kathryn J; Karst, Nathaniel; Jones, Laura E; Seeley, Thomas D

    2013-11-07

    In the beeswax combs of honey bees, the cells of brood, pollen, and honey have a consistent spatial pattern that is sustained throughout the life of a colony. This spatial pattern is believed to emerge from simple behavioral rules that specify how the queen moves, where foragers deposit honey/pollen and how honey/pollen is consumed from cells. Prior work has shown that a set of such rules can explain the formation of the allocation pattern starting from an empty comb. We show that these rules cannot maintain the pattern once the brood start to vacate their cells, and we propose new, biologically realistic rules that better sustain the observed allocation pattern. We analyze the three resulting models by performing hundreds of simulation runs over many gestational periods and a wide range of parameter values. We develop new metrics for pattern assessment and employ them in analyzing pattern retention over each simulation run. Applied to our simulation results, these metrics show alteration of an accepted model for honey/pollen consumption based on local information can stabilize the cell allocation pattern over time. We also show that adding global information, by biasing the queen's movements towards the center of the comb, expands the parameter regime over which pattern retention occurs. © 2013 Published by Elsevier Ltd. All rights reserved.

  7. The research for the clinical curative effect through combing traditional Chinese medicine with insulin to cure diabetes.

    Science.gov (United States)

    Wu, Qianfeng; Fan, Hongxia

    2014-07-01

    The clinical curative effect is observed through curing type 2 diabetes mellitus with the therapy of combing Traditional Chinese Medicine (TCM) with insulin. Both the insulin prescription and the treatment of traditional Chinese medicine prescription are applied as mutual comparison. And the dosage, time, blood sugar level and curative effect etc are recorded. Healthy human body is taken as comparison for monitoring physical indicators. Through comparing insulin prescription and the combing therapy of insulin and traditional Chinese medicine, the insulin treatment group is better than contrast group (Pblending use group, the ISI in each group is significantly lower than that of health control group (P<0.01), where accumulation of damp heat in spleen type is the lowest; the BM I, H bA1C of type 2 diabetic patient is higher than health control group, its accumulation of damp heat in spleen type is the highest, TC, TG typical accumulation of damp heat in spleen are higher than other pattern of syndrome. the treatment method of combing TCM with insulin in curing type 2 diabetes mellitus has better effect than using insulin treatment alone; the resistance degree of insulin demonstrates the changing trend of first increase and later decrease with the development of disease course. Accumulation of damp heat in spleen type accounts for the highest proportion in type 2 diabetic patients, and there exists serious insulin resistance.

  8. Synthesis and photoluminescence properties of comb-like CdS nanobelt/ZnO nanorod heterostructures

    International Nuclear Information System (INIS)

    Lan Changyong; Gong Jiangfeng; Liu Chunming

    2012-01-01

    Highlights: ► Comb-like CdS nanobelt/ZnO nanorod heterostructures were synthesized. ► ZnO nanorods epitaxially grew on the (1 0 0) surface of the CdS nanobelts along [1 0 0]. ► A preliminary growth mechanism was proposed. - Abstract: Comb-like CdS nanobelt/ZnO nanorod heterostructures were synthesized by a two-stage method. X-ray diffractometer, scanning electron microscopy, transmission electron microscopy were used to characterize and analyze the as-synthesized products. The results demonstrate that the CdS nanobelt backbones grow along [2 1 0] and the ZnO nanorod branches epitaxially grow on the (0 0 1) surface of the CdS nanobelt with a growth direction of [0 0 1]. The as-prepared heterostructures exhibit an important feature of single-crystallinity. At room temperature, the comb-like CdS nanobelt/ZnO nanorod heterostructures show strong green emission.

  9. The Matter and Imagery of Air in Eduardo Chillida’s The Comb of the Wind XV

    Directory of Open Access Journals (Sweden)

    Mei-Hsin Chen

    2017-08-01

    Full Text Available Eduardo Chillida’s The Comb of the Wind XV, embedded in natural rocks rising from the Cantabrian Ocean in 1977, expresses the artistic potential of air as a material, a metaphor, and as an art-maker. With this sculpture, Chillida opened up the possibility for air itself to show indefinite imageries. Although much has been written about this sculptural group from different perspectives, no study has been systematically undertaken to analyze it regarding the theme of the matter of air, which should be considered the core of the work of art. As Gaston Bachelard stated: ‘Chillida wished the iron [of The Comb of the Wind XV] to show aerial realities.’ Hence, this article seeks to study to what ‘aerial realities’ Chillida might refer, and the relationship between air and his artwork. First, this paper delves into the meanings and functions that air involves in Chillida’s artwork, as well as into how the sculptor embodied his poetic of air and allowed the spectator to perceive his sculptural installation with five senses. Also, the interaction between Chillida’s work and Luis Peña Ganchegui’s architectural installation La Plaza del Tenis is examined under the scope of Martin Heidegger’s notion of place. All these aspects are discussed to help readers realize why the air in natural motion is the foundation of The Comb of the Wind XV, and map the holistic imagery of air that Chillida intended to express.

  10. Sex Education: Another View

    Science.gov (United States)

    Hamilton, Jennifer

    1977-01-01

    The mother of a 14-year-old mentally retarded boy comments on the viewpoints of Dr. Sol Gordon (a sex education columnist) regarding masturbation, questions on sex, marriage, and the parents' role. (SBH)

  11. Sex in situ

    DEFF Research Database (Denmark)

    Krøgholt, Ida

    2017-01-01

    Sex er en del af vores sociale praksis og centralt for det, vi hver især er. Men bortset fra pornoindustrien, har vi ikke mange muligheder for at få adgang til billeder af sex. Teater Nordkrafts forestilling Sex in situ vil gøre seksuelle billeder til noget, der kan deles, udveksles og tales om, og...

  12. Coeducation and Sex Roles.

    Science.gov (United States)

    Harris, Mary B.

    1986-01-01

    A study of the sex role stereotypes held by 538 first-term Australian university students from single-sex and coeducational high schools is presented. Results suggest that coeducational schooling may have some advantages for fostering interactions with the opposite sex. (MSE)

  13. sex and Cannibalism

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 12. The Secret Sex Lives of Rotifers Sex - sex and Cannibalism. T Ramakrishna Rao. General Article Volume 5 Issue 12 December 2000 pp 41-47. Fulltext. Click here to view fulltext PDF. Permanent link:

  14. Re-examination of the taxonomic status of Enterobacter helveticus, Enterobacter pulveris and Enterobacter turicensis as members of the genus Cronobacter and their reclassification in the genera Franconibacter gen. nov. and Siccibacter gen. nov. as Franconibacter helveticus comb. nov., Franconibacter pulveris comb. nov. and Siccibacter turicensis comb. nov., respectively.

    Science.gov (United States)

    Stephan, Roger; Grim, Christopher J; Gopinath, Gopal R; Mammel, Mark K; Sathyamoorthy, Venugopal; Trach, Larisa H; Chase, Hannah R; Fanning, Séamus; Tall, Ben D

    2014-10-01

    Recently, a taxonomical re-evaluation of the genus Enterobacter, based on multi-locus sequence typing (MLST) analysis, has led to the proposal that the species Enterobacter pulveris, Enterobacter helveticus and Enterobacter turicensis should be reclassified as novel species of the genus Cronobacter. In the present work, new genome-scale analyses, including average nucleotide identity, genome-scale phylogeny and k-mer analysis, coupled with previously reported DNA-DNA hybridization values and biochemical characterization strongly indicate that these three species of the genus Enterobacter are not members of the genus Cronobacter, nor do they belong to the re-evaluated genus Enterobacter. Furthermore, data from this polyphasic study indicated that all three species constitute two new genera. We propose reclassifying Enterobacter pulveris and Enterobacter helveticus in the genus Franconibacter gen. nov. as Franconibacter pulveris comb. nov. (type strain 601/05(T) = LMG 24057(T) = DSM 19144(T)) and Franconibacter helveticus comb. nov. (type strain 513/05(T) = LMG 23732(T) = DSM 18396(T)), respectively, and Enterobacter turicensis in the genus Siccibacter gen. nov. as Siccibacter turicensis comb. nov. (type strain 508/05(T) = LMG 23730(T) = DSM 18397(T)).

  15. Vertical comb drive actuator for the measurement of piezoelectric coefficients in small-scale systems

    International Nuclear Information System (INIS)

    Wooldridge, J; Muniz-Piniella, A; Stewart, M; Shean, T A V; Weaver, P M; Cain, M G

    2013-01-01

    A micro-electro-mechanical systems (MEMS) vertical levitation comb drive actuator has been created for the measurement of piezoelectric coefficients in thin/thick films or piezoelectrically active micro-scale components of other MEMS devices. The device exerts a dynamic force of 33 μN at an applied voltage of 100 V. The charge developed on the piezoelectric test device is measured using a charge sensitive pre-amplifier and lock-in technique, enabling measurements down to 1×10 −5 pC. The system was tested with ten different piezoelectric samples with coefficients in the range 70–1375 pC N −1 and showed a good correlation (r = 0.9997) to measurements performed with macroscopic applied stresses, and piezoelectric impedance resonance techniques. The measurement of the direct piezoelectric effect in micro- and nano-scale piezo-materials has been made possible using MEMS processing technology. This new application of a MEMS metrology device has been developed and fully characterized in order to accurately evaluate the functional properties of piezoelectric materials at the scale required in micro- to nano-scale applications. (paper)

  16. Scanning Frequncy Comb Microscopy; a New Tool with Sub-Nm Resolution

    Science.gov (United States)

    Hagmann, Mark; Yarotski, Dmitry

    2016-03-01

    The quasi-periodic excitation of a tunneling junction by a mode-locked ultrafast laser generates a regular sequence of femtosecond pulses of electrons at the pulse repetition rate fR of the laser to be superimposed on the dc tunneling current. In the frequency domain this is equivalent to a microwave frequency comb (MFC) of harmonics at integer multiples of fR. Using a metal tip and sample in a scanning tunneling microscope and a mode-locked Ti:Sapphire laser with a fR of 74.254 MHz, the 200th harmonic at 14.85 GHz has a signal-to-noise ratio of 20 dB, and a linewidth art for narrow-linewidth in a microwave source. The decay in the amplitude of the harmonics with increasing frequency corresponds to a time constant of 320 ps which is attributed to 6.4 pF of shunting capacitance near the junction and the 50 Ω load of the spectrum analyzer. Spreading resistance in semiconductor samples causes the measured attenuation to be sensitive to the local concentration of the carriers. The laser photon energy must be less than the bandgap energy to prevent the creation of electron-hole pairs which would cause surge currents that interfere with the measurements. 2880 S. Main Street #214, Salt Lake City, Utah 84115, USA.

  17. Design of a MEMS Capacitive Comb-drive Micro-accelerometer with Sag Optimization

    Directory of Open Access Journals (Sweden)

    B. D. PANT

    2009-10-01

    Full Text Available The current paper presents an optimization study for the designing of a highly sensitive inertial grade capacitive accelerometer based on comb-drive actuation and sensing. The proof mass, suspension system (beams or tethers, stators and rotors have to be realized through an HAR (high aspect ratio DRIE (deep reactive ion etching process for which process optimization has already been done at our laboratory. As the proof mass is a bulk micro-machined structure having a mass in milligram range, the optimum positioning of the tethers on the proof mass is important to have minimum sag, necessary to reduce the off-axis sensitivity. The optimization for the positioning of the tethers has been carried out using a commercial software tool ANSYSTM Multiphysics. The accelerometer has been modeled analytically to predict its characteristics. The dependency of sensitivity on the dimensions of the suspension beams (tethers has also been verified using the above FEM software tool. The present device has been designed to deliver a high sensitivity of 13.6 mV/g/V for low-g applications.

  18. Nocturia improvement in the combination of Avodart(®) and tamsulosin (CombAT) study.

    Science.gov (United States)

    Oelke, Matthias; Roehrborn, Claus G; D'Ancona, Carlos; Wilson, Timothy H; Castro, Ramiro; Manyak, Michael

    2014-10-01

    The purpose of the study was to assess the impact of dutasteride plus tamsulosin combination therapy, compared with dutasteride or tamsulosin monotherapy, on nocturia in men with lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH) using data from the 4-year CombAT study. Nocturia was assessed using Question 7 of the International Prostate Symptom Score questionnaire. Efficacy measures included as follows: mean change in nocturia at 3-month intervals up to 48 months; proportion of patients with improvement/worsening in nocturia; nocturnal voiding frequency at baseline and study end, overall and by baseline subgroups; and nocturnal voiding frequency tamsulosin -0.3). Reduction in nocturia score with combination therapy was significantly (p ≤ 0.01) better than tamsulosin monotherapy across all baseline subgroups tested, except for men with previous 5ARI use. Among those with a baseline IPSS Q7 score ≥ 2, more patients with combination therapy had a score tamsulosin (26 %, p tamsulosin monotherapies. These analyses are the first to show greater improvement with a 5ARI/α-blocker combination versus either agent alone for the management of nocturia in patients with LUTS/BPH.

  19. Electrostatic Comb-Drive Actuator with High In-Plane Translational Velocity

    Directory of Open Access Journals (Sweden)

    Yomna M. Eltagoury

    2016-10-01

    Full Text Available This work reports the design and opto-mechanical characterization of high velocity comb-drive actuators producing in-plane motion and fabricated using the technology of deep reactive ion etching (DRIE of silicon-on-insulator (SOI substrate. The actuators drive vertical mirrors acting on optical beams propagating in-plane with respect to the substrate. The actuator-mirror device is a fabrication on an SOI wafer with 80 μm etching depth, surface roughness of about 15 nm peak to valley and etching verticality that is better than 0.1 degree. The travel range of the actuators is extracted using an optical method based on optical cavity response and accounting for the diffraction effect. One design achieves a travel range of approximately 9.1 µm at a resonance frequency of approximately 26.1 kHz, while the second design achieves about 2 µm at 93.5 kHz. The two specific designs reported achieve peak velocities of about 1.48 and 1.18 m/s, respectively, which is the highest product of the travel range and frequency for an in-plane microelectromechanical system (MEMS motion under atmospheric pressure, to the best of the authors’ knowledge. The first design possesses high spring linearity over its travel range with about 350 ppm change in the resonance frequency, while the second design achieves higher resonance frequency on the expense of linearity. The theoretical predications and the experimental results show good agreement.

  20. Molecular self assembly of mixed comb-like dextran surfactant polymers for SPR virus detection.

    Science.gov (United States)

    Mai-Ngam, Katanchalee; Kiatpathomchai, Wansika; Arunrut, Narong; Sansatsadeekul, Jitlada

    2014-11-04

    The synthesis of two comb-like dextran surfactant polymers, that are different in their dextran molecular weight (MW) distribution and the presence of carboxylic groups, and their characterization are reported. A bimodal carboxylic dextran surfactant polymer consists of poly(vinyl amine) (PVAm) backbone with carboxyl higher MW dextran, non-functionalized lower MW dextran and hydrophobic hexyl branches; while a monomodal dextran surfactant polymer is PVAm grafted with non-functionalized lower MW dextran and hexyl branches. Layer formation of non-covalently attached dextran chains with bimodal MW distributions on a surface plasmon resonance (SPR) chip was investigated from the perspective of mixed physisorption of the bimodal and monomodal surfactant polymers. Separation distances between the carboxylic longer dextran side chains within the bimodal surfactant polymer and between the whole bimodal surfactant molecules on the chip surface could be well-controlled. SPR analysis of shrimp yellow head virus using our mixed surfactant chips showed dependence on synergetic adjustment of these separation distances. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Frequency comb calibrated frequency-sweeping interferometry for absolute group refractive index measurement of air.

    Science.gov (United States)

    Yang, Lijun; Wu, Xuejian; Wei, Haoyun; Li, Yan

    2017-04-10

    The absolute group refractive index of air at 194061.02 GHz is measured in real time using frequency-sweeping interferometry calibrated by an optical frequency comb. The group refractive index of air is calculated from the calibration peaks of the laser frequency variation and the interference signal of the two beams passing through the inner and outer regions of a vacuum cell when the frequency of a tunable external cavity diode laser is scanned. We continuously measure the refractive index of air for 2 h, which shows that the difference between measured results and Ciddor's equation is less than 9.6×10-8, and the standard deviation of that difference is 5.9×10-8. The relative uncertainty of the measured refractive index of air is estimated to be 8.6×10-8. The data update rate is 0.2 Hz, making it applicable under conditions in which air refractive index fluctuates fast.

  2. Parasitic effects in superconducting quantum interference device-based radiation comb generators

    Energy Technology Data Exchange (ETDEWEB)

    Bosisio, R., E-mail: riccardo.bosisio@nano.cnr.it [SPIN-CNR, Via Dodecaneso 33, 16146 Genova (Italy); NEST, Instituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa (Italy); Giazotto, F., E-mail: giazotto@sns.it [NEST, Instituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa (Italy); Solinas, P., E-mail: paolo.solinas@spin.cnr.it [SPIN-CNR, Via Dodecaneso 33, 16146 Genova (Italy)

    2015-12-07

    We study several parasitic effects on the implementation of a Josephson radiation comb generator based on a dc superconducting quantum interference device (SQUID) driven by an external magnetic field. This system can be used as a radiation generator similarly to what is done in optics and metrology, and allows one to generate up to several hundreds of harmonics of the driving frequency. First we take into account how the assumption of a finite loop geometrical inductance and junction capacitance in each SQUID may alter the operation of the devices. Then, we estimate the effect of imperfections in the fabrication of an array of SQUIDs, which is an unavoidable source of errors in practical situations. We show that the role of the junction capacitance is, in general, negligible, whereas the geometrical inductance has a beneficial effect on the performance of the device. The errors on the areas and junction resistance asymmetries may deteriorate the performance, but their effect can be limited to a large extent by a suitable choice of fabrication parameters.

  3. CREASING BEHAVIOR OF SOME WOVEN MATERIALS MADE FROM COMBED YARNS TYPE

    Directory of Open Access Journals (Sweden)

    HRISTIAN Liliana

    2017-05-01

    Full Text Available The paper analyses the behavior to creasing of some woven materials made from yarns type wool used for ready-made clothes. Factors like fibrous composition, properties of constituent fibers, wovens structure parameters, mechanical properties of warp and weft yarns and finishing treatments that influenced the recovery capacity from crease/folding were investigated experimentally through several tests which revealed their importance in the process. The creasing of woven materials made from combed yarns type wool used for ready-clothes is an undesired deformation effect with temporary or permanent character, which is caused by a composed strain of bending and compression during utilization, processing or maintenance. It is manifested by the appearance of wrinkles, folds or stripes on the surface of wovens materials, thus diminishing their qualitative appearance and also their practical value. Creasing is the result of irreversible changes created through the reciprocal sliding of structural fiber components when exposed to a bending strain. Creasing is specific to oriented structures with high crystallinity (cellulosic fibers. The sliding appears because of hydrogen bond breaking which can, however, reform easy in other positions conferring a permanent character to creasing.Functional apparel will be subjected to a wide range of end uses such that a garment will be affected by intern (fibres, yarn fineness warp/weft, fabric density, thickness, fabric count and external factors (external environment - exposure to sunlight, wind, rain, cold weather conditions, fabric/human body interaction. These factors affect the performance and behaviour of functional.

  4. Comb-push ultrasound shear elastography of breast masses: initial results show promise.

    Science.gov (United States)

    Denis, Max; Mehrmohammadi, Mohammad; Song, Pengfei; Meixner, Duane D; Fazzio, Robert T; Pruthi, Sandhya; Whaley, Dana H; Chen, Shigao; Fatemi, Mostafa; Alizad, Azra

    2015-01-01

    To evaluate the performance of Comb-push Ultrasound Shear Elastography (CUSE) for classification of breast masses. CUSE is an ultrasound-based quantitative two-dimensional shear wave elasticity imaging technique, which utilizes multiple laterally distributed acoustic radiation force (ARF) beams to simultaneously excite the tissue and induce shear waves. Female patients who were categorized as having suspicious breast masses underwent CUSE evaluations prior to biopsy. An elasticity estimate within the breast mass was obtained from the CUSE shear wave speed map. Elasticity estimates of various types of benign and malignant masses were compared with biopsy results. Fifty-four female patients with suspicious breast masses from our ongoing study are presented. Our cohort included 31 malignant and 23 benign breast masses. Our results indicate that the mean shear wave speed was significantly higher in malignant masses (6 ± 1.58 m/s) in comparison to benign masses (3.65 ± 1.36 m/s). Therefore, the stiffness of the mass quantified by the Young's modulus is significantly higher in malignant masses. According to the receiver operating characteristic curve (ROC), the optimal cut-off value of 83 kPa yields 87.10% sensitivity, 82.61% specificity, and 0.88 for the area under the curve (AUC). CUSE has the potential for clinical utility as a quantitative diagnostic imaging tool adjunct to B-mode ultrasound for differentiation of malignant and benign breast masses.

  5. Update on Breast Cancer Detection Using Comb-Push Ultrasound Shear Elastography.

    Science.gov (United States)

    Denis, Max; Bayat, Mahdi; Mehrmohammadi, Mohammad; Gregory, Adriana; Song, Pengfei; Whaley, Dana H; Pruthi, Sandhya; Chen, Shigao; Fatemi, Mostafa; Alizad, Azra

    2015-09-01

    In this work, tissue stiffness estimates are used to differentiate between benign and malignant breast masses in a group of pre-biopsy patients. The rationale is that breast masses are often stiffer than healthy tissue; furthermore, malignant masses are stiffer than benign masses. The comb-push ultrasound shear elastography (CUSE) method is used to noninvasively assess a tissue's mechanical properties. CUSE utilizes a sequence of simultaneous multiple laterally spaced acoustic radiation force (ARF) excitations and detection to reconstruct the region of interest (ROI) shear wave speed map, from which a tissue stiffness property can be quantified. In this study, the tissue stiffnesses of 73 breast masses were interrogated. The mean shear wave speeds for benign masses (3.42 ± 1.32 m/s) were lower than malignant breast masses (6.04 ± 1.25 m/s). These speed values correspond to higher stiffness in malignant breast masses (114.9 ± 40.6 kPa) than benign masses (39.4 ± 28.1 kPa and p 83 kPa is established as a cut-off value for differentiating between malignant and benign suspicious breast masses, with a receiver operating characteristic curve (ROC) of 89.19% sensitivity, 88.69% specificity, and 0.911 for the area under the curve (AUC).

  6. Comb-push ultrasound shear elastography of breast masses: initial results show promise.

    Directory of Open Access Journals (Sweden)

    Max Denis

    Full Text Available To evaluate the performance of Comb-push Ultrasound Shear Elastography (CUSE for classification of breast masses.CUSE is an ultrasound-based quantitative two-dimensional shear wave elasticity imaging technique, which utilizes multiple laterally distributed acoustic radiation force (ARF beams to simultaneously excite the tissue and induce shear waves. Female patients who were categorized as having suspicious breast masses underwent CUSE evaluations prior to biopsy. An elasticity estimate within the breast mass was obtained from the CUSE shear wave speed map. Elasticity estimates of various types of benign and malignant masses were compared with biopsy results.Fifty-four female patients with suspicious breast masses from our ongoing study are presented. Our cohort included 31 malignant and 23 benign breast masses. Our results indicate that the mean shear wave speed was significantly higher in malignant masses (6 ± 1.58 m/s in comparison to benign masses (3.65 ± 1.36 m/s. Therefore, the stiffness of the mass quantified by the Young's modulus is significantly higher in malignant masses. According to the receiver operating characteristic curve (ROC, the optimal cut-off value of 83 kPa yields 87.10% sensitivity, 82.61% specificity, and 0.88 for the area under the curve (AUC.CUSE has the potential for clinical utility as a quantitative diagnostic imaging tool adjunct to B-mode ultrasound for differentiation of malignant and benign breast masses.

  7. Fibre multi-wave mixing combs reveal the broken symmetry of Fermi-Pasta-Ulam recurrence

    Science.gov (United States)

    Mussot, Arnaud; Naveau, Corentin; Conforti, Matteo; Kudlinski, Alexandre; Copie, Francois; Szriftgiser, Pascal; Trillo, Stefano

    2018-05-01

    In optical fibres, weak modulations can grow at the expense of a strong pump to form a triangular comb of sideband pairs, until the process is reversed. Repeated cycles of such conversion and back-conversion constitute a manifestation of the universal nonlinear phenomenon known as Fermi-Pasta-Ulam recurrence. However, it remains a major challenge to observe the coexistence of different types of recurrences owing to the spontaneous symmetry-breaking nature of such a phenomenon. Here, we implement a novel non-destructive technique that allows the evolution in amplitude and phase of frequency modes to be reconstructed via post-processing of the fibre backscattered light. We clearly observe how control of the input modulation seed results in different recursive behaviours emerging from the phase-space structure dictated by the spontaneously broken symmetry. The proposed technique is an important tool to characterize other mixing processes and new regimes of rogue-wave formation and wave turbulence in fibre optics.

  8. Highly Stable Wideband Microwave Extraction by Synchronizing Widely Tunable Optoelectronic Oscillator with Optical Frequency Comb

    Science.gov (United States)

    Hou, D.; Xie, X. P.; Zhang, Y. L.; Wu, J. T.; Chen, Z. Y.; Zhao, J. Y.

    2013-12-01

    Optical frequency combs (OFCs), based on mode-locked lasers (MLLs), have attracted considerable attention in many fields over recent years. Among the applications of OFCs, one of the most challenging works is the extraction of a highly stable microwave with low phase noise. Many synchronisation schemes have been exploited to synchronise an electronic oscillator with the pulse train from a MLL, helping to extract an ultra-stable microwave. Here, we demonstrate novel wideband microwave extraction from a stable OFC by synchronising a single widely tunable optoelectronic oscillator (OEO) with an OFC at different harmonic frequencies, using an optical phase detection technique. The tunable range of the proposed microwave extraction extends from 2 GHz to 4 GHz, and in a long-term synchronisation experiment over 12 hours, the proposed synchronisation scheme provided a rms timing drift of 18 fs and frequency instabilities at 1.2 × 10-15/1 s and 2.2 × 10-18/10000 s.

  9. Revision of the Megaperidae Manter, 1934 n. comb. (Syn. Apocreadiidae Skrjabin, 1942) including a reorganization of the Schistorchiinae Yamaguti, 1942.

    Science.gov (United States)

    Blend, Charles K; Karar, Yasser F M; Dronen, Norman O

    2017-11-28

    Modified and/or new keys to the four subfamilies now recognized within the Megaperidae Manter, 1934 n. comb. (Syn. Apocreadiidae Skrjabin, 1942) as well as the genera within each subfamily are presented. Two new genera, Paraschistorchis n. gen. and Plesioschistorchis n. gen., both within the Schistorchiinae Yamaguti, 1942, are erected and keys are provided to the species considered in both new genera-distinguished by possessing caeca that end either in separate ani or blindly. Plesioschistorchis callyodontis (Yamaguti, 1942) n. comb. and Plesioschistorchis haridis (Nagaty, 1957) n. comb. are re-described from new material collected from the common parrotfish, Scarus psittacus Forsskål (Perciformes: Scaridae), inhabiting the Red Sea off Egypt; S. psittacus represents a new host record for both species. The taxonomic status of Schistorchis sensu stricto Lühe, 1906 is examined and revised, a key to the four species we consider in this genus offered, and the monotypic genus Megacreadium Nagaty, 1956 declared a junior synonym of Schistorchis. Members of Schistorchis sensu stricto possess a unique "complex" (i.e. highly cellular/glandular) instead of "simple" (i.e. entirely muscular) type of oral sucker that is quite large in relation to body size; an elongate, somewhat sub-rectangular-shaped body; 5+ testes arranged in at least two rows; caeca that open via separate ani; a long post-testicular region; a median genital pore either at the anterior margin of or just anterior to the ventral sucker; and species of Schistorchis sensu stricto parasitize the intestine of marine fish within the Order Tetraodontiformes Berg. With the revision of this genus, we re-describe Schistorchis carneus Lühe, 1906 from the lower and mid-intestine of the white-spotted puffer, Arothron hispidus (Linnaeus) (Tetraodontiformes: Tetraodontidae), collected in the Red Sea off Egypt. Finally, a plea is made for further study of the Megaperidae n. comb. focusing, in particular, on the following

  10. The role of volatile-saturation and adiabatic ascent of moderately hydrous melts on the formation of orbicules and comb layers in shallow subvolcanic conduits (Fisher Lake, Sierra Nevada).

    Science.gov (United States)

    McCarthy, A. J.; Müntener, O.

    2016-12-01

    Orbicules and comb layers are enigmatic features found sparsely distributed along plutonic contacts in a wide range of igneous environments. We provide new insights into the mechanisms responsible for the formation of these features by studying the spatial distribution, mineralogy and geochemistry of comb layers and orbicules from the Northern Sierra Nevada, Fisher Lake (USA). Over a range of studied comb textured layering, we show that the large majority of comb layers are cumulates formed by the initiation of plagioclase growth as a comb textured mineral. Plagioclase fractionation is followed by pyroxenes + oxides fractionation. Continuous crystal fractionation and conductive cooling from the host rock leads to amphibole saturation and the formation of late stage comb textured amphibole, leading to the formation of plagioclase- and plagioclase-amphibole comb textures. The lack of amphibole comb textures on orbicule rims as opposed to their widespread occurrence in comb layers, suggests that the presence of a thermal gradient plays an important role in diversifying comb textures. We propose that comb layers and orbicules are unique features which are controlled by the volatile content of ascending melts and ascent mechanisms. Thermodynamic calculations indicate that near-adiabatic decompression of water-undersaturated melts (ca. 4wt% H2O) through the crust will lead to superheating and dissolution of pre-existing minerals. Upon saturation of volatiles at shallow depth, degassing-induced undercooling of the decompressing melt will trigger heterogeneous nucleation of plagioclase on host rocks and remobilized xenoliths. The rarity of orbicules and comb layers in volcanic and plutonic rocks worldwide suggests that adiabatic decompression of moderately hydrous melts leading to superheating is a rare phenomena, with most arc melts ascending and cooling in small reservoirs throughout the crust, prior to emplacement at shallow depth as crystal-bearing magmas.

  11. Why we should consider sex (and study sex differences) in addiction research.

    Science.gov (United States)

    Sanchis-Segura, Carla; Becker, Jill B

    2016-09-01

    Among mammals, every cell has a biological sex, and the sex of an individual pervades its body and brain. In this review, we describe the processes through which mammals become phenotypically male or female by organizational and activational influences of genes and hormones throughout development. We emphasized that the molecular and cellular changes triggered by sex chromosomes and steroid hormones may generate sex differences in overt physiological functions and behavior, but they may alternatively promote end-point convergences between males and females. Clinical and pre-clinical evidences suggest that sex and gender differences modulate drug consumption as well as of the transition towards drug-promoted pathological states such as dependence and addiction. Additionally, sex differences in drug pharmacokinetics and pharmacodynamics will also influence dependence and addiction as well as side effects of drugs. These effects will further interact with socially gendered factors to result in sex differences in the access to, engagement in and efficacy of any therapeutic attempt. Finally, we maintain that 'sex sameness' is as important as 'sex differences' when building a complete understanding of biology for both males and females and provide a framework with which to classify and guide investigation into the mechanisms mediating sex differences and sex sameness. © 2016 Society for the Study of Addiction.

  12. Structure and thermal performance of poly(styrene-co-maleic anhydride)-g-alkyl alcohol comb-like copolymeric phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haixia; Shi, Haifeng, E-mail: haifeng.shi@gmail.com; Qi, Miao; Zhang, Lingjian; Zhang, Xingxiang; Qi, Lu

    2013-07-20

    Graphical abstract: SMA-g-CnOH comb-like PCMs exhibit the better thermal stability against 1-alcohols due to the protection of SMA backbones, and the degradation temperature is dependent on the side-chain length, where at 5 wt% weight loss T{sub d} increased from 193 to 257 °C with n changing from 14 to 26. SMA-g-CnOH PCMs can be widely used under 300 °C for preparation of energy-saving products and materials. - Highlights: • The length of alkyl side-chains determines the thermal energy storage ability. • SMA backbone restricts the crystallization of alkyl side groups. • SMA-g-CnOH PCMs have the better thermal stability against 1-alcohols. - Abstract: A series of comb-like copolymeric phase change materials (SMA-g-CnOH) composed of poly(styrene-co-maleic anhydride) (SMA) and 1-alcohols CnOH with n = 14, 16, 18 or 26, respectively, was synthesized through grafting reaction. The structure and thermal properties of SMA-g-CnOH were investigated by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD). The DSC analysis indicates that SMA-g-CnOH exhibit good structure stability with phase change enthalpies changing from 37.9 to 110.7 J g{sup −1}. The results showed that the low thermal efficiency of SMA-g-CnOH was ascribed to the small CH{sub 2} segments of side chains participating in the assembled structure of side-chain crystallites. Their advantageous structural stability and thermal performance of SMA-g-CnOH were favorable for phase change materials in the thermal energy storage systems. Additionally, the influence of side-chain length on thermal properties of SMA-g-CnOH also was discussed in detail in combination with the published results.

  13. A Sex Work Research Symposium: Examining Positionality in Documenting Sex Work and Sex Workers’ Rights

    OpenAIRE

    Megan Lowthers; Magdalena Sabat; Elya M. Durisin; Kamala Kempadoo

    2017-01-01

    Historically, academic literature on sex work has documented the changing debates, policies, and cultural discourse surrounding the sex industry, and their impact on the rights of sex workers worldwide. As sex work scholars look to the future of sex workers’ rights, however, we are also in a critical moment of self-reflection on how sex work scholarship engages with sex worker communities, produces knowledge surrounding sex work, and represents the lived experiences of sex workers’ rights, or...

  14. Female Sex Offenders: Public Awareness and Attributions.

    Science.gov (United States)

    Cain, Calli M; Anderson, Amy L

    2016-12-01

    Traditional gender roles, sex scripts, and the way female sex offenders are portrayed in the media may lead to misconceptions about who can commit sexual offenses. Sexual crimes by women may go unnoticed or unreported if there is a general lack of awareness that females commit these crimes. Data from the 2012 Nebraska Annual Social Indicators Survey were used to determine whether the public perceives women as capable sex offenders and the perceived causes of female sex offending. The traditional focus on male sex offenders by researchers, media, and politicians, in addition to gender stereotypes, introduces the possibility of group differences (e.g., between men and women) in perceptions of female sex offenders. Consequently, two secondary analyses were conducted that tested for group differences in both the public's perception of whether females can commit sex offenses and the explanations selected for why females sexually offend. The findings suggest that the public does perceive women as capable sex offenders, although there were group differences in the causal attributions for female sex offending.

  15. Neuroprotection of Sex Steroids

    Science.gov (United States)

    Liu, Mingyue; Kelley, Melissa H.; Herson, Paco S.; Hurn, Patricia D.

    2011-01-01

    Sex steroids are essential for reproduction and development in animals and humans, and sex steroids also play an important role in neuroprotection following brain injury. New data indicate that sex-specific responses to brain injury occur at the cellular and molecular levels. This review summarizes the current understanding of neuroprotection by sex steroids, particularly estrogen, androgen, and progesterone, based on both in vitro and in vivo studies. Better understanding of the role of sex steroids under physiological and pathological conditions will help us to develop novel effective therapeutic strategies for brain injury. PMID:20595940

  16. Sexing young snowy owls

    Science.gov (United States)

    Seidensticker, M.T.; Holt, D.W.; Detienne, J.; Talbot, S.; Gray, K.

    2011-01-01

    We predicted sex of 140 Snowy Owl (Bubo scandiacus) nestlings out of 34 nests at our Barrow, Alaska, study area to develop a technique for sexing these owls in the field. We primarily sexed young, flightless owls (3844 d old) by quantifying plumage markings on the remiges and tail, predicting sex, and collecting blood samples to test our field predictions using molecular sexing techniques. We categorized and quantified three different plumage markings: two types of bars (defined as markings that touch the rachis) and spots (defined as markings that do not touch the rachis). We predicted sex in the field assuming that males had more spots than bars and females more bars than spots on the remiges and rectrices. Molecular data indicated that we correctly sexed 100% of the nestlings. We modeled the data using random forests and classification trees. Both models indicated that the number and type of markings on the secondary feathers were the most important in classifying nestling sex. The statistical models verified our initial qualitative prediction that males have more spots than bars and females more bars than spots on flight feathers P6P10 for both wings and tail feathers T1 and T2. This study provides researchers with an easily replicable and highly accurate method for sexing young Snowy Owls in the field, which should aid further studies of sex-ratios and sex-related variation in behavior and growth of this circumpolar owl species. ?? 2011 The Raptor Research Foundation, Inc.

  17. HairMax LaserComb laser phototherapy device in the treatment of male androgenetic alopecia: A randomized, double-blind, sham device-controlled, multicentre trial.

    Science.gov (United States)

    Leavitt, Matt; Charles, Glenn; Heyman, Eugene; Michaels, David

    2009-01-01

    The use of low levels of visible or near infrared light for reducing pain, inflammation and oedema, promoting healing of wounds, deeper tissue and nerves, and preventing tissue damage has been known for almost 40 years since the invention of lasers. The HairMax LaserComb is a hand-held Class 3R lower level laser therapy device that contains a single laser module that emulates 9 beams at a wavelength of 655 nm (+/-5%). The device uses a technique of parting the user's hair by combs that are attached to the device. This improves delivery of distributed laser light to the scalp. The combs are designed so that each of the teeth on the combs aligns with a laser beam. By aligning the teeth with the laser beams, the hair can be parted and the laser energy delivered to the scalp of the user without obstruction by the individual hairs on the scalp. The primary aim of the study was to assess the safety and effectiveness of the HairMax LaserComb laser phototherapy device in the promotion of hair growth and in the cessation of hair loss in males diagnosed with androgenetic alopecia (AGA). This double-blind, sham device-controlled, multicentre, 26-week trial randomized male patients with Norwood-Hamilton classes IIa-V AGA to treatment with the HairMax LaserComb or the sham device (2 : 1). The sham device used in the study was identical to the active device except that the laser light was replaced by a non-active incandescent light source. Of the 110 patients who completed the study, subjects in the HairMax LaserComb treatment group exhibited a significantly greater increase in mean terminal hair density than subjects in the sham device group (p laser phototherapy device for the treatment of AGA in males.

  18. Osho - Insights on sex.

    Science.gov (United States)

    Nagaraj, Anil Kumar Mysore

    2013-01-01

    Sex is a mysterious phenomenon, which has puzzled even great sages. Human beings have researched and mastered the biology of sex. But that is not all. Sex needs to be understood from the spiritual perspective too. The vision of Osho is an enlightening experience in this regard. Out of the thousands of lectures, five lectures on sex made Osho most notorious. Born into a Jain family of Madhya Pradesh, Rajneesh, who later wanted himself to be called Osho, is a great master. He has spoken volumes on a wide range of topics ranging from sex to super-consciousness. His contributions in the area of sex are based on the principles of "Tantra" which has its origin from Buddhism. This article focuses on his life and insights on sex, which if understood properly, can be a stepping stone for enlightenment.

  19. Helping Behavior: Effects of Sex and Sex-Typing.

    Science.gov (United States)

    Basow, Susan A.; Crawley, Donna M.

    1982-01-01

    Male and female experimenters requested adult shoppers (N=178) to fill out a questionnaire. Refusal data showed shoppers helping other-sex more than same-sex experimenters. Other results showed a significant three-way interaction among helper and helpee sex and sex-typing and situation sex-typing and that helper sex-typing did not have significant…

  20. Sex differentials in mortality.

    Science.gov (United States)

    1970-06-01

    The questions leing considered are whether a higher female than male mortality rate exists in Ceylon, India, and Pakistan, and whether this sex differential can account for the observed high male sex ratios. There is a choice between explaining the recorded masculinity of the Indian population by assuming that the subordinate position of women caused their omission from the census or that it caused their unrecorded death in childhood. The 1951 census report of India states that there is a traditional fondness for male issues in most parts of the country and a corresponding dislike for female children. However, a life table for India applied to the 1951 census gave a higher average female age at death 34.7 years as opposed to 33.5 years for male. Other estimates for India and Pakistan for the period 1951-1961 give 37.8 years for life expectancy for males and 36.98 for females. In 1953 the female death rate in Ceylon was over 80% higher than that of the males in the most reproductive ages, 20-29. In 1963 the female excess mortality at the same ages was still 25%, and in the age group 30-34 almost a 1/3 higher. In India the female death rate at ages 15-44 was 38% higher than that of the males in the 1958-1959 survey and as much as 174% higher in the Khanna rural survey, 1956-1960. In Pakistan a Population growth Estimate experiment conducted during 1962-1965 on a national probability sample has shown that in the ages 15-44 the female death rate was 75% higher than that of the males. High maternal mortality was the major reason. In addition, female mortality among young children over age 1 year was 24% higher in 1965 and 1963. There was little difference between the rates of mortality of the 2 sexes at age 45 and above. Recent trends in Ceylon show considerable improvement in maternal mortality which has reduced by 22% the ratio of female to male mortality at age 15-44. Also the ratio at ages 1-9 fell by 8%. to .1 of a year for every calendar year to 1980.

  1. Measurements of CO2, CH4, H2O, and HDO over a 2-km Outdoor Path with Dual-Comb Spectroscopy

    Science.gov (United States)

    Rieker, G. B.; Giorgetta, F. R.; Coddington, I.; Swann, W. C.; Sinclair, L. C.; Cromer, C.; Baumann, E.; Newbury, N. R.; Kofler, J.; Petron, G.; Sweeney, C.; Tans, P. P.

    2013-12-01

    We demonstrate simultaneous sensing of CO2, CH4, H2O, and HDO over a 2-km outdoor open air path using dual-frequency-comb absorption spectroscopy (DCS). Our implementation of the DCS technique simultaneously offers broad spectral coverage (>8 THz, 267 cm-1) and fine spectral point spacing (100 MHz, 0.0033 cm-1) with a coherent eye-safe beam. The spectrometer, which is adapted from [Zolot et al., 2012], consists of two mutually coherent Erbium-doped fiber frequency-comb lasers which create a broad spectrum of perfectly spaced narrow linewidth frequency elements (';comb teeth') near 1.6 μm. The comb light is transmitted by a telescope and active steering mirrors from the roof of the NIST Boulder laboratory to a 50-cm flat mirror located 1 km away. The return light is received by a second telescope and carried via multimode fiber to a detector. The greenhouse gas absorption attenuates the teeth from the two combs that are coincident with the relevant molecular resonant frequencies. We purposefully offset the frequencies between the two frequency combs in a Vernier-like fashion so that each pair of comb teeth from the two combs results in a unique rf heterodyne beat frequency on the photodiode. The spectral spacing between subsequent comb teeth pairs is 100 MHz, far lower than the ~4 GHz linewidths of small molecule absorption features in the atmosphere. Because of the narrow comb linewidth, there is an essentially negligible instrument lineshape. The measured absorption spectrum can thus resolve neighboring absorption features of different species, and can be compared directly with HITRAN and recent greenhouse gas absorption models developed for satellite- and ground-based carbon observatories to determine the path-integrated concentrations of the absorbing species. Measurements covering the complete 30013←00001 absorption band of CO2 and absorption features of CH4, H2O and HDO between 1.6-1.67 μm were performed under a variety of atmospheric conditions. During

  2. High-coherence mid-infrared dual-comb spectroscopy spanning 2.6 to 5.2 μm

    Science.gov (United States)

    Ycas, Gabriel; Giorgetta, Fabrizio R.; Baumann, Esther; Coddington, Ian; Herman, Daniel; Diddams, Scott A.; Newbury, Nathan R.

    2018-04-01

    Mid-infrared dual-comb spectroscopy has the potential to supplant conventional Fourier-transform spectroscopy in applications requiring high resolution, accuracy, signal-to-noise ratio and speed. Until now, mid-infrared dual-comb spectroscopy has been limited to narrow optical bandwidths or low signal-to-noise ratios. Using digital signal processing and broadband frequency conversion in waveguides, we demonstrate a mid-infrared dual-comb spectrometer covering 2.6 to 5.2 µm with comb-tooth resolution, sub-MHz frequency precision and accuracy, and a spectral signal-to-noise ratio as high as 6,500. As a demonstration, we measure the highly structured, broadband cross-section of propane from 2,840 to 3,040 cm-1, the complex phase/amplitude spectra of carbonyl sulfide from 2,000 to 2,100 cm-1, and of a methane, acetylene and ethane mixture from 2,860 to 3,400 cm-1. The combination of broad bandwidth, comb-mode resolution and high brightness will enable accurate mid-infrared spectroscopy in precision laboratory experiments and non-laboratory applications including open-path atmospheric gas sensing, process monitoring and combustion.

  3. Gingival blood flow under total combs by functional pressure evaluated with laser-Doppler flowmetry, a non-invasive method of blood flow measurement

    International Nuclear Information System (INIS)

    Hengl, St.

    1996-09-01

    Gingival blood flow under total-combs by functional pressure evaluated with Laser-Doppler Flowmetry, a non-invasive method of blood flow measurement. Microcirculation of gum's capillary system can be measured non-invasive by Laser-Doppler-Flowmetry (LDF). Circulation, defined by the number of floating erythrocytes per unit of time, is measured by a fibro-optical Laser-Doppler-Flowmetry. The task was to examine, if there is any change of gum's circulation during strain and relief. Circulation on defined measurepoints, divided on the four quadrants, was determined among maximal strain and subsequent relief, on one probationer (complete denture bearer). Before every measure session systemic pressure was taken. LDF-value was taken on top of jaw-comb, in doing so, to get reproducible result and a satisfying fixation of the probe, there was made an artificial limb of the upper and lower comb. In the upper comb a dynamometer-box, which determined minimal and maximal comb pressure, was integrated. The received results of the LDF-measurement, expressed as perfusion units (PU) were lower under applied pressure than by pressure points more distant. Hyperemia, resulting during relief, seemed the more intense, the less perfusion was before. This new, non-invasive kind of circulation measurement seems to be quite predestined to be used for gingival diagnostic under artificial limb in the future. (author)

  4. Effect of ultrasonic degradation of hyaluronic acid extracted from rooster comb on antioxidant and antiglycation activities.

    Science.gov (United States)

    Hafsa, Jawhar; Chaouch, Mohamed Aymen; Charfeddine, Bassem; Rihouey, Christophe; Limem, Khalifa; Le Cerf, Didier; Rouatbi, Sonia; Majdoub, Hatem

    2017-12-01

    Recently, low-molecular-weight hyaluronic acid (LMWHA) has been reported to have novel features, such as free radical scavenging activities, antioxidant activities and dietary supplements. In this study, hyaluronic acid (HA) was extracted from rooster comb and LMWHA was obtained by ultrasonic degradation in order to assess their antioxidant and antiglycation activities. Molecular weight (Mw) and the content of glucuronic acid (GlcA) were used as the index for comparison of the effect of ultrasonic treatment. The effects on the structure were determined by ultraviolet (UV) spectra and Fourier transform infrared spectra (FTIR). The antioxidant activity was determined by three analytical assays (DPPH, NO and TBARS), and the inhibitory effect against glycated-BSA was also assessed. The GlcA content of HA and LMWHA was estimated at about 48.6% and 47.3%, respectively. The results demonstrate that ultrasonic irradiation decreases the Mw (1090-181 kDa) and intrinsic viscosity (1550-473 mL/g), which indicate the cleavage of the glycosidic bonds. The FTIR and UV spectra did not significantly change before and after degradation. The IC 50 value of HA and LWMHA was 1.43, 0.76 and 0.36 mg/mL and 1.20, 0.89 and 0.17 mg/mL toward DPPH, NO and TBARS, respectively. Likewise LMWHA exhibited significant inhibitory effects on the AGEs formation than HA. The results demonstrated that the ultrasonic irradiation did not damage and change the chemical structure of HA after degradation; furthermore, decreasing Mw and viscosity of LMWHA after degradation may enhance the antioxidant and antiglycation activity.

  5. Phylogenetic data suggest the reclassification of Fasciola jacksoni (Digenea: Fasciolidae) as Fascioloides jacksoni comb. nov.

    Science.gov (United States)

    Heneberg, Petr

    2013-04-01

    Fasciola jacksoni (Cobbold, 1869) is a highly prevalent (18-62%) species colonizing the liver (less frequently the lungs, kidneys, pericardia, and intestines) of Elephas maximus indicus and Elephas maximus maximus in the Indomalayan region, causing cirrhosis, hemorrhages, and connective tissue proliferation. The phylogenetic relationships of Fasciola jacksoni in relation to representative species of the superfamily Echinostomatoidea was assessed using four independent DNA regions. The analysis involved conserved (28S rDNA) and highly variable (ITS1, ITS2, and ND1) loci utilizing both mitochondrial (ND1) and nuclear (28S rDNA, ITS1, and ITS2) DNA. Although the analyses confirmed the monophyletic origin of the Fasciolidae family, all four analyzed regions suggested high similarity of Fasciola jacksoni to Fascioloides magna, member of a hitherto monotypic genus, parasitizing a variety of wild and domestic ruminants through the Holarctic. Supporting evidence stems also from the morphological similarities, host spectrum overlaps, and similarities in disease onset and progression. Fasciola jacksoni was reclassified to its genus in the nineteenth century by Cobbold based on the shared possession of dendriform system of gastric canals. However, Fascioloides magna (discovered later) shares this feature as well. Conversely, Fascioloides magna and Fasciola hepatica possess long median intestinal branches, whereas relatively shorter median intestinal branches are characteristic for Fasciola hepatica and Fasciola gigantica only. Both, Fascioloides magna and Fasciola hepatica, are also similar in their possession of small, but distinctive cephalic cone, while the larger one is typical for Fasciola hepatica and Fasciola gigantica. Reflecting the combined data, reclassification of Fasciola jacksoni as Fascioloides jacksoni comb. nov. is suggested.

  6. a Thz Photomixing Synthesizer Based on a Fiber Frequency Comb for High Resolution Rotational Spectroscopy

    Science.gov (United States)

    Hindle, Francis; Mouret, Gael; Cuisset, Arnaud; Yang, Chun; Eliet, Sophie; Bocquet, Robin

    2010-06-01

    To date the principal application for photomixing sources has been for high resolution spectroscopy of gases due to the large tuning range and spectral purity. New Developments of the Opto-Electronic THz Spectrometer have been performed in order to obtain a powerful tool for High-Resolution Spectroscopy. The combination of two extended cavity laser diodes and fast charge carrier lifetime semiconductor materials has allowed a continuous-wave THz spectrometer to be constructed based on optical heterodyning. Unlike many THz sources, this instrument gives access to all frequencies in the range 0.3 to 3.5 THz with a resolution of 1 MHz. The main spectroscopic applications of this spectrometer were dedicated to line profile analysis of rotational transitions referenced in the spectroscopic databases. One limitation of the THz spectrometer was accuracy with which the generated frequency is known. Recently, this obstacle has been circled with the construction of a photomixing spectrometer where the two pump lasers are phase locked to two modes of a repetition rate stabilized frequency doubled fiber laser frequency comb. In order to achieve a tuning range in excess to 100 MHz a third cw laser was required in the new configuration of the THz spectrometer. To assess the performances of this instrument, the frequencies of the pure rotational transitions of OCS molecules have been measured between 0,8 to 1,2 THz. A rms inferior to 100 kHz, deduced from the frequencies measured, demonstrates that the THz photomixing synthesizer is now able to be competitive with microwave and submillimeter techniques. S. Matton, F. Rohart, R. Bocquet, D. Bigourd, A. Cuisset, F. Hindle, G. Mouret, J. Mol. Spectrosc., 2006, 239: 182. C. Yang, J. Buldyreva, I. E. Gordon, F. Rohart, A. Cuisset, G. Mouret, R. Bocquet, F. Hindle, J. Quant. Spectrosc. Radiat. Transfer, 2008, 109: 2857. G. Mouret, F. Hindle, A. Cuisset, C. Yang, R. Bocquet, M. Lours, D. Rovera, Opt. Express, 2009, 17: 22031.

  7. Judging The Effectiveness Of Wool Combing By The Entropy Of The Images Of Wool Slivers

    Science.gov (United States)

    Rodrigues, F. Carvalho; Carvalho, Fernando D.; Peixoto, J. Pinto; Silva, M. Santos

    1989-04-01

    In general it can be said that the textile industry endeavours to render a bunch of fibers chaotically distributed in space into an ordered spatial distribution. This fact is independent of the nature the fibers, i.e., the aim of getting into higher order states in the spatial distribution of the fibers dictates different industrial processes depending on whether the fibers are wool, cotton or man made but the all effect is centred on obtaining at every step of any of the processes a more ordered state regarding the spatial distribution of the fibers. Thinking about the textile processes as a method of getting order out of chaos, the concept of entropy appears as the most appropriate judging parameter on the effectiveness of a step in the chain of an industrial process to produce a regular textile. In fact, entropy is the hidden parameter not only for the textile industry but also for the non woven and paper industrial processes. It happens that in these industries the state of order is linked with the spatial distribution of fibers and to obtain an image of a spatial distribution is an easy matter. To compute the image entropy from the grey level distribution requires only the use of the Shannon formula. In this paper to illustrate the usefulness of employing the entropy of an image concept to textiles the evolution of the entropy of wool slivers along the combing process is matched against the state of parallelization of the fibbers along the seven steps as measured by the existing method. The advantages of the entropy method over the previous method based on diffraction is also demonstrated.

  8. Salinifilum gen. nov., with description of Salinifilum proteinilyticum sp. nov., an extremely halophilic actinomycete isolated from Meighan wetland, Iran, and reclassification of Saccharopolyspora aidingensis as Salinifilum aidingensis comb. nov. and Saccharopolyspora ghardaiensis as Salinifilum ghardaiensis comb. nov.

    Science.gov (United States)

    Moshtaghi Nikou, Mahdi; Ramezani, Mohaddaseh; Harirchi, Sharareh; Makzoom, Somayyeh; Amoozegar, Mohammad Ali; Shahzadeh Fazeli, Seyed Abolhassan; Schumann, Peter; Ventosa, Antonio

    2017-10-01

    A Gram-positive, halophilic actinobacterial strain Miq-12 T was isolated from Meighan wetland in Iran. Strain Miq-12 T was strictly aerobic, catalase positive and oxidase negative. The isolate grew at 12-25 % NaCl, at 30-50 °C and pH 5.5-10.5. The optimum NaCl, temperature and pH for growth were 15-20 %, 40 °C and 7.0-8.0, respectively. The cell wall of strain Miq-12 T contained meso-diaminopimelic acid as diagnostic diamino acid and arabinose as whole-cell sugar. The polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine and phosphatidylinositol. It synthesized cellular fatty acids of anteiso and iso-branched types, anteiso-C17 : 0, iso-C17:0, iso-C15:0, iso-C16 : 0. The major respiratory quinone was MK-9(H4). The G+C content of its genomic DNA was 72.1 mol%. Phylogenetic analysis based on 16S rRNA gene sequence comparison revealed that strain Miq-12 T belongs to the family Pseudonocardiaceae, constituted a separate clade, and showed the closest phylogenetic similarity to Saccharopolyspora aidingensis TRM 46074 T (96.99 %) and Saccharopolyspora ghardaiensis CCUG 63370 T (96.92 %). On the basis of phylogenetic analysis, phenotypic and chemotaxonomic characteristics, a novel genus and species of the family Pseudonocardiaceae, Salinifilum proteinilyticum gen. nov., sp. nov., are proposed. The type strain is Miq-12 T (=IBRCM 11033 T =LMG 28390 T ). We also propose that S. aidingensis and S. ghardaiensis should be transferred to this new genus and be named Salinifilum aidingensis comb. nov. and Salinifilum ghardaiensis comb. nov., respectively. The type strain of Salinifilum aidingensis comb. nov. is TRM 46074 T (=CCTCCAA 2012014 T =JCM 30185 T ) and the type strain of Salinifilum ghardaiensis comb. nov. is CCUG 63370 T (=DSM 45606 T =CECT 8304 T ).

  9. Doing gender in sex and sex research.

    Science.gov (United States)

    Vanwesenbeeck, Ine

    2009-12-01

    Gender is central to sexuality, and vice versa, but there are a number of difficulties with the treatment of gender in sex research. Apparently, it is hard to find a balance between two conflicting needs. First, obviously, it is necessary to make distinctions between women and men, for political as well as research-technical and theoretical reasons. A second requirement, at odds with the first one, is the necessity to understand gender and its relation to sexuality and the body as much more complex than simplistically referring to two sets of individuals. This is all the more necessary when one realizes the possible drawbacks of exaggerating the differences between the sexes (in particular when they are biologically explained), because of stereotyping, stigmatizing, and expectancy confirmatory processes. This essay identifies and discusses 10 difficulties in the treatment of gender in sex research, reflects on their origins, and reviews theory and evidence with the aim to (1) consider the relative strength of gender/sex as an explanatory variable compared to other factors and processes explaining differences between men and women on a number of sexual aspects, (2) inform an understanding of gender and its relation to sexuality as an ongoing, open-ended, multi-determined, situated, interactional process, with the body as a third player, and (3) argue in favor of a nuanced, well-balanced treatment of gender in sex research.

  10. Sex reversal in vertebrates

    OpenAIRE

    2016-01-01

    This special topic issue of Sexual Development gives an overview of sex reversal in vertebrates, from fishes naturally changing their sex, to rodents escaping the mammalian SRY-determining system. It offers eight up-to-date reviews on specific subjects in sex reversal, considering fishes, amphibians, reptiles, birds, marsupials, and placental mammals, including humans. The broad scope of represented animals makes this ideal for students and researchers, especially those interested in the...

  11. Sex reduces genetic variation: a multidisciplinary review.

    Science.gov (United States)

    Gorelick, Root; Heng, Henry H Q

    2011-04-01

    For over a century, the paradigm has been that sex invariably increases genetic variation, despite many renowned biologists asserting that sex decreases most genetic variation. Sex is usually perceived as the source of additive genetic variance that drives eukaryotic evolution vis-à-vis adaptation and Fisher's fundamental theorem. However, evidence for sex decreasing genetic variation appears in ecology, paleontology, population genetics, and cancer biology. The common thread among many of these disciplines is that sex acts like a coarse filter, weeding out major changes, such as chromosomal rearrangements (that are almost always deleterious), but letting minor variation, such as changes at the nucleotide or gene level (that are often neutral), flow through the sexual sieve. Sex acts as a constraint on genomic and epigenetic variation, thereby limiting adaptive evolution. The diverse reasons for sex reducing genetic variation (especially at the genome level) and slowing down evolution may provide a sufficient benefit to offset the famed costs of sex. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.

  12. Rediscovery and redescription of the sharpshooter Kogigonalia incarnata (Germar, 1821), comb. n. (Hemiptera, Cicadellidae, Cicadellini) from the Atlantic Forest of Brazil, with a key to the species of the genus

    Science.gov (United States)

    Mejdalani, Gabriel; Cavichioli, Rodney R.; Silva, Roberta Santos; Quintas, Victor

    2015-01-01

    Abstract The Brazilian sharpshooter Tettigonia incarnata Germar, 1821 was treated as incertae sedis in the most comprehensive and recent monograph of the New World Cicadellini. We have been able to identify male and female specimens of Tettigonia incarnata from northeastern and southeastern Brazil using high-resolution images of two syntypes deposited in the Museum für Naturkunde, Universität Humboldt, Berlin. Here we transfer Tettigonia incarnata to the genus Kogigonalia Young, 1977 and provide a detailed redescription of this species, including information on intraspecific color variation. In addition, we provide an updated key to the species of Kogigonalia. This is the first record of the genus from Brazil. Kogigonalia incarnata comb. n. can be recognized, among other features, by the subgenital plates with a distinct emargination at outer margin, aedeagus with a ventral unpaired process near midlength of shaft, and female sternite VII bearing an elongate strong projection on posterior margin. PMID:25632255

  13. Test Research of Reducing Combed Yarn Neps%降低精梳纱棉结的试验研究

    Institute of Scientific and Technical Information of China (English)

    赵建伟

    2011-01-01

    Technology measures of reducing combed yarn neps were discussed.Causes of combed yarn neps formation and changing rules in spinning were analyzed.Cotton assorting and processing configurations in each process were modified and optimized.Basic management works were enhanced such as raw cotton selection, equipment clean, operation clean and temperature & humidity control.Finally neps of CJ 18.2 tex cheese and CJ 22.4 tex cheese could be kept below 31 per kilometer and 25 per kilometer.It is pointed out that processing in cotton assorting,carding and combing process should be set rationally,reducing neps is a system project,the key points should be focused, whole process control should be implemented and basic management should be strengthened, finally the better effect could be got.%探讨降低精梳纱棉结的技术措施.分析了精梳纱棉结的形成原因及纺纱过程中的变化规律,通过对配棉及各工序的工艺进行改进和优化配置,加强原棉、设备揩车和运转清洁工作及温湿度等各项基础管理工作,结果使CJ 18.2 tex、CJ 22.4 tex筒纱棉结长期保持在31个/km和25个/km以下.指出:减少精梳纱棉结是一项系统工程,仅仅依靠配棉、梳棉、精梳工序的作用是不够的,应突出重点实行纺纱全过程控制并切实加强基础性管理工作,才能收到较好效果.

  14. Optical Frequency Comb Fourier Transform Spectroscopy with Resolution Exceeding the Limit Set by the Optical Path Difference

    Science.gov (United States)

    Foltynowicz, Aleksandra; Rutkowski, Lucile; Johanssson, Alexandra C.; Khodabakhsh, Amir; Maslowski, Piotr; Kowzan, Grzegorz; Lee, Kevin; Fermann, Martin

    2015-06-01

    Fourier transform spectrometers (FTS) based on optical frequency combs (OFC) allow detection of broadband molecular spectra with high signal-to-noise ratios within acquisition times orders of magnitude shorter than traditional FTIRs based on thermal sources. Due to the pulsed nature of OFCs the interferogram consists of a series of bursts rather than a single burst at zero optical path difference (OPD). The comb mode structure can be resolved by acquiring multiple bursts, in both mechanical FTS systems and dual-comb spectroscopy. However, in all existing demonstrations the resolution was ultimately limited either by the maximum available OPD between the interferometer arms or by the total acquisition time enabled by the storage memory. We present a method that provides spectral resolution exceeding the limit set by the maximum OPD using an interferogram containing only a single burst. The method allows measurements of absorption lines narrower than the OPD-limited resolution without any influence of the instrumental lineshape function. We demonstrate this by measuring undistorted CO2 and CO absorption lines with linewidth narrower than the OPD-limited resolution using OFC-based mechanical FTS in the near- and mid-infrared wavelength ranges. The near-infrared system is based on an Er:fiber femtosecond laser locked to a high finesse cavity, while the mid-infrared system is based on a Tm:fiber-laser-pumped optical parametric oscillator coupled to a multi-pass cell. We show that the method allows acquisition of high-resolution molecular spectra with interferometer length orders of magnitude shorter than traditional FTIR. Mandon, J., G. Guelachvili, and N. Picque, Nat. Phot., 2009. 3(2): p. 99-102. Zeitouny, M., et al., Ann. Phys., 2013. 525(6): p. 437-442. Zolot, A.M., et al., Opt. Lett., 2012. 37(4): p. 638-640.

  15. Memristor comprising film with comb-like structure of nanocolumns of metal oxide embedded in a metal oxide matrix

    Science.gov (United States)

    Driscoll, Judith L; Lee, ShinBuhm; Jia, Quanxi

    2015-05-12

    Films having a comb-like structure of nanocolumns of Sm.sub.2O.sub.3 embedded in a SrTiO.sub.3 formed spontaneously on a substrate surface by pulsed laser deposition. In an embodiment, the nanocolumns had a width of about 20 nm with spaces between nanocolumns of about 10 nm. The films exhibited memristive behavior, and were extremely uniform and tunable. Oxygen deficiencies were located at vertical interfaces between the nanocolumns and the matrix. The substrates may be single-layered or multilayered.

  16. Observations on Dissocladella annulata (Elliott, 1993 nov. comb. (Calcareous algae, Dasycladales from the Cenomanian of west Serbia

    Directory of Open Access Journals (Sweden)

    Radoičić Rajka

    2010-01-01

    Full Text Available Based on material from the type area at Tetrebovo in the Zlatibor massif of WSerbia, the Cenomanian dasycladalean alga originally described as Harlanjohnsonella annulata by ELLIOTT (1968, typified 1993 in: GRANIER & DELOFFRE, is emended and revisited as Dissocladella annulata (ELLIOTT nov. comb. The evidence of tufts of short secondaries arising at the top of the drop-like primaries allows its transfer to the genus Dissocladella PIA, 1936. This species displays a different degree of skeleton calcification which is described in detail. The monospecific genus Harlanjohnsonella ELLIOTT becomes invalid, as being a junior synonym of Dissocladella.

  17. Multiple optical code-label processing using multi-wavelength frequency comb generator and multi-port optical spectrum synthesizer.

    Science.gov (United States)

    Moritsuka, Fumi; Wada, Naoya; Sakamoto, Takahide; Kawanishi, Tetsuya; Komai, Yuki; Anzai, Shimako; Izutsu, Masayuki; Kodate, Kashiko

    2007-06-11

    In optical packet switching (OPS) and optical code division multiple access (OCDMA) systems, label generation and processing are key technologies. Recently, several label processors have been proposed and demonstrated. However, in order to recognize N different labels, N separate devices are required. Here, we propose and experimentally demonstrate a large-scale, multiple optical code (OC)-label generation and processing technology based on multi-port, a fully tunable optical spectrum synthesizer (OSS) and a multi-wavelength electro-optic frequency comb generator. The OSS can generate 80 different OC-labels simultaneously and can perform 80-parallel matched filtering. We also demonstrated its application to OCDMA.

  18. Voting on pensions: sex and marriage

    OpenAIRE

    Leroux, Marie-Louise; Pestieau, Pierre; Racionero, Maria

    2009-01-01

    Existing political economy models of pensions focus on age and productivity. In this paper we incorporate two additional individual characteristics: sex and marital status. We ignore the role of age, by assuming that people vote at the start of their life, and characterize the preferred rate of taxation that finances a Beveridgean pension scheme when individuals differ in wage, sex and marital status. We allow for two types of couples: one-breadwinner and two-breadwinner couples. Marriage poo...

  19. Combining combing and secondary ion mass spectrometry to study DNA on chips using 13C and 15N labeling [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Armelle Cabin-Flaman

    2016-06-01

    Full Text Available Dynamic secondary ion mass spectrometry (D-SIMS imaging of combed DNA – the combing, imaging by SIMS or CIS method – has been developed previously using a standard NanoSIMS 50 to reveal, on the 50 nm scale, individual DNA fibers labeled with different, non-radioactive isotopes in vivo and to quantify these isotopes. This makes CIS especially suitable for determining the times, places and rates of DNA synthesis as well as the detection of the fine-scale re-arrangements of DNA and of molecules associated with combed DNA fibers. Here, we show how CIS may be extended to 13C-labeling via the detection and quantification of the 13C14N- recombinant ion and the use of the 13C:12C ratio, we discuss how CIS might permit three successive labels, and we suggest ideas that might be explored using CIS.

  20. Tunable and switchable all-fiber comb filter using a PBS-based two-stage cascaded Mach-Zehnder interferometer

    Science.gov (United States)

    Luo, Zhi-Chao; Luo, Ai-Ping; Xu, Wen-Cheng

    2011-08-01

    We propose and demonstrate a novel tunable and switchable all-fiber comb filter by employing a polarization beam splitter (PBS)-based two-stage cascaded Mach-Zehnder (M-Z) interferometer. The proposed comb filter consists of a rotatable polarizer, a fiber PBS, a non-3-dB coupler and a 3-dB coupler. By simply adjusting the polarization state of the input light, the dual-function of channel spacing tunable and wavelength switchable (interleaving) operations can be efficiently obtained. The theoretical analysis is verified by the experimental results. A comb filter with both the channel spacing tunable from 0.18 nm to 0.36 nm and the wavelength switchable functions is experimentally demonstrated.

  1. Sex tourism in Thailand.

    Science.gov (United States)

    Van Kerkwijk, C

    1992-01-01

    Many foreigners visit Thailand in search of sex. While long-distance tourism was long enjoyed by members of more privileged social classes, even the lower economical classes of Japan, Malaysia, Europe, America, and Australia can now afford to travel over long distances. This relatively new breed of tourist is more likely to be of lower socioeconomic and educational status and less likely to use condoms when having sex. An estimated 30,000 sex workers are active in Bangkok, of whom 7000/10,000 are females who work specifically in the tourism sector. 1/2-1/3 of the 600 commercial sex establishments in the city are visited by foreigners. Phuket, Pattaya, Koh Samui, and Chiangmai are also well-frequented by sex tourists. Overall, a large, diverse, inexpensive, and accessible commercial sex market exists in Thailand. One may meet sex workers quasi-ubiquitously and be assured to find someone capable of meeting one's sexual needs. With these attributes, Thailand strongly attracts tourists in search of sex. A certain degree of recklessness also prevails among those on vacation. Away from the peers and social mores of their native lands, tourists may engage in sexually activities without criticism. Likewise, Thai sex workers who cater to foreigners, especially females, enjoy more freedom and control in sexual relations than their peers who work among nationals. Neither single nor married women in Thailand are allowed much sexual freedom and are traditionally expected to be obliging docile, and submissive. The greater than normal personal latitude enjoyed by both sex worker and foreigner lead to more negotiation on condom use and overall lower use. As such, Thailand's commercial sex market with foreigners' involvement therein threatens to spread HIV to many other countries throughout the world.

  2. The evolution of sex ratios and sex-determining systems

    NARCIS (Netherlands)

    Uller, Tobias; Pen, Ido; Wapstra, Erik; Beukeboom, Leo W.; Komdeur, Jan

    Sex determination is a fundamental process governed by diverse mechanisms. Sex ratio selection is commonly implicated in the evolution of sex-determining systems, although formal models are rare. Here, we argue that, although sex ratio selection can induce shifts in sex determination, genomic

  3. Two-Stage System Based on a Software-Defined Radio for Stabilizing of Optical Frequency Combs in Long-Term Experiments

    Directory of Open Access Journals (Sweden)

    Martin Čížek

    2014-01-01

    Full Text Available A passive optical resonator is a special sensor used for measurement of lengths on the nanometer and sub-nanometer scale. A stabilized optical frequency comb can provide an ultimate reference for measuring the wavelength of a tunable laser locked to the optical resonator. If we lock the repetition and offset frequencies of the comb to a high-grade radiofrequency (RF oscillator its relative frequency stability is transferred from the RF to the optical frequency domain. Experiments in the field of precise length metrology of low-expansion materials are usually of long-term nature so it is required that the optical frequency comb stay in operation for an extended period of time. The optoelectronic closed-loop systems used for stabilization of combs are usually based on traditional analog electronic circuits processing signals from photodetectors. From an experimental point of view, these setups are very complicated and sensitive to ambient conditions, especially in the optical part, therefore maintaining long-time operation is not easy. The research presented in this paper deals with a novel approach based on digital signal processing and a software-defined radio. We describe digital signal processing algorithms intended for keeping the femtosecond optical comb in a long-time stable operation. This need arose during specialized experiments involving measurements of optical frequencies of tunable continuous-wave lasers. The resulting system is capable of keeping the comb in lock for an extensive period of time (8 days or more with the relative stability better than 1.6 × 10−11.

  4. Proposal for creation of a new genus Neomicrococcus gen. nov. to accommodate Zhihengliuella aestuarii Baik et al. 2011 and Micrococcus lactis Chittpurna et al. 2011 as Neomicrococcus aestuarii comb. nov. and Neomicrococcus lactis comb. nov.

    Science.gov (United States)

    Prakash, Om; Sharma, Avinash; Nimonkar, Yogesh; Shouche, Yogesh S

    2015-11-01

    Micrococcus lactis and Zhihengliuella aestuarii were described independently in 2011. Their type strains showed high levels of 16S rRNA gene sequence similarity (99.3%). Phylogenetic analysis revealed that M. lactis MCC 2278T and Z. aestuarii JCM 16166T formed a monophyletic group and showed distant relationships to other members of closely related genera such as Micrococcus, Zhihengliuella, Arthrobacter and Citricoccus. The presence of large proportions of iso-C14:0 and iso-C16:0 with small amounts of iso-C15:0 distinguished M. lactis MCC 2278T and Z. aestuarii JCM 16166T from other members of the genera Micrococcus and Zhihengliuella. Unlike other members of the genera Zhihengliuella and Micrococcus, M. lactis MCC 2278T and Z. aestuarii JCM 16166T showed growth at low concentrations of NaCl. Thus, based on distinctive phylogenetic, chemotaxonomic and physiological features of these two organisms in comparison with other members of the genera Micrococcus and Zhihengliuella, it is clear that they do not fit within the existing classification and deserve separate status. DNA-DNA hybridization between the two type strains was 63%, indicating that they represent separate species. In this study, we propose the creation of a novel genus, Neomicrococcus gen. nov., to accommodate the two species with Neomicrococcus aestuarii gen. nov., comb. nov. (type strain JCM 16166T = KCTC 19557T) as the type species. Neomicrococcus lactis comb. nov. (type strain MCC 2278T = DSM 23694T) is also proposed.

  5. Tomaculocystis corpulenta n. gen., n. sp. (Apicomplexa: Eugregarinorida) parasitizing the little yellow cockroach, Cariblatta lutea (Blattodea: Ectobiidae), in Alabama and Florida with recognition of Tomaculocystis cylindrosa n. comb. and Tomaculocystis mukundai n. comb. parasitizing ectobiid cockroaches in India.

    Science.gov (United States)

    Clopton, Richard E

    2015-02-01

    Tomaculocystis corpulenta n. gen., n. sp. (Apicomplexa: Eugregarinorida: Septatorina: Gregarinidae) is described from populations of the little yellow cockroach, Cariblatta lutea (Blattodea: Ectobiidae), established in laboratory culture from samples collected in Alabama and Florida. Tomaculocystis n. gen. are differentiated from other members of Gregarina by a markedly elliptoid gametocyst inside a persistent, lomentiform hyaline epicyst; developmental organization and growth of the spore tubes from gametocyst surface tumidi; and dehiscence by extrusion of non-chain forming oocysts through spore tubes that barely extend beyond the epicyst wall. Gregarina cylindrosa, Gregarina discocephala, and Gregarina mukundai are recognized as members of Tomaculocystis, and G. cylindrosa is recognized as the senior synonym of G. discocephala. Thus, Tomaculocystis cylindrosa n. comb. and Tomaculocystis mukundai n. comb. are formed. Species of Tomaculocystis are distinguished based on gamont deutomerite and oocyst shape and size. The oocysts of T. corpulenta are broadly dolioform, lack 4 polar knobs, and possess distinct, unique polar plates. Oocysts of all other known species in the genus are more oblong in shape, possess 4 polar knobs, and lack the distinct polar plates observed in the oocysts of T. corpulenta. Host utilization and geographic distribution among gregarine genera parasitizing the cockroach family Ectobiidae reveal a pattern of host-parasite specificity linking gregarine genera with ectobiidid subfamilies. Overall patterns suggest a hypothesis of European endemicy for Gamocystis, but hypotheses for the origin and radiation of Tomaculocystis or species of Gregarina infecting cockroaches are confounded by the cosmopolitan spread of pest cockroach species among humans.

  6. Sex Determination, Sex Ratios, and Genetic Conflict

    NARCIS (Netherlands)

    Werren, John H.; Beukeboom, Leo W.

    1998-01-01

    Genetic mechanisms of sex determination are unexpectedly diverse and change rapidly during evolution. We review the role of genetic conflict as the driving force behind this diversity and turnover. Genetic conflict occurs when different components of a genetic system are subject to selection in

  7. Insects and sex

    NARCIS (Netherlands)

    Beukeboom, Leo

    2005-01-01

    Most organisms reproduce sexually, but the evolution of sexual reproduction is not yet well understood. Sexual reproduction leads to new variation and adaptations to the environment, but sex is also costly. Some insects reproduce without sex through parthenogenesis or paedogenesis. Almost all sexual

  8. Sex Away from Home

    Science.gov (United States)

    Greenwald, Harold

    1971-01-01

    The reasons why people who are normally truthful to their spouses engage in sex away from home are discussed. These reasons can include loneliness, ego building or the opportunity to have homosexual relations. Sex away from home is likely to increase since the number of people traveling is increasing. (Author/CG)

  9. Single-Sex Classrooms

    Science.gov (United States)

    Protheroe, Nancy

    2009-01-01

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

  10. Sex Education Materials.

    Science.gov (United States)

    Singer-Magdoff, Laura

    1969-01-01

    After briefly discussing the philosophy of sex education and appraising generally the nature of the instructional methods and materials currently in use in the schools, the author provides brief but incisive reviews of a number of films, filmstrips, and other instructional materials dealing with sex. The reviews are continued in the succeeding…

  11. Comb-like optical transmission spectra generated from one-dimensional two-segment-connected two-material waveguide networks optimized by genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Yang, Xiangbo, E-mail: xbyang@scnu.edu.cn [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); School of Physical Education and Sports Science, South China Normal University, Guangzhou 510006 (China); Lu, Jian; Zhang, Guogang [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Liu, Chengyi Timon [School of Physical Education and Sports Science, South China Normal University, Guangzhou 510006 (China)

    2014-03-01

    In this Letter, a one-dimensional (1D) two-segment-connected two-material waveguide network (TSCTMWN) is designed to produce comb-like frequency passbands, where each waveguide segment is composed of normal and anomalous dispersion materials and the length ratio of sub-waveguide segments is optimized by genetic algorithm (GA). It is found that 66 comb-like frequency passbands are created in the second frequency unit, maximal relative width difference of which is less than 2×10{sup −5}. It may be useful for the designing of dense wavelength division multiplexings (DWDMs) and multi-channel filters, etc., and provide new applications for GA.

  12. 10 GHz frequency comb spectral broadening in AlGaAs-on-Insulator nano-waveguide with ultra-low pump power

    DEFF Research Database (Denmark)

    Hu, Hao; Pu, Minhao; Yvind, Kresten

    2017-01-01

    We experimentally demonstrated 10 GHz frequency comb spectral broadening with a 30-dB bandwidth of 238 nm in an 11-mm long AlGaAsOI nano-waveguide. The 10-GHz 230-fs pump pulse has an average power of only 12 mW.......We experimentally demonstrated 10 GHz frequency comb spectral broadening with a 30-dB bandwidth of 238 nm in an 11-mm long AlGaAsOI nano-waveguide. The 10-GHz 230-fs pump pulse has an average power of only 12 mW....

  13. “Would you like to meet the secret Beat?” – Tram Combs and a Beat poetry less celebrated

    DEFF Research Database (Denmark)

    Sørensen, Bent

    of the poetry of Tram Combs, “the secret Beat”, whose 1957 collection Pilgrim’s Terrace contained forewords by both William Carlos Williams and Kenneth Rexroth, and whose collaborators included Allen Ginsberg – yet whose name is persistently left out of the Beat canon. One wonders why, when he is an example...... directly at Gorm, and asked: “Would you like to meet the secret Beat, then?” The old gentleman proceeded to introduce himself as Tram Combs, poet, bookseller, nude model and gay man about town, and for the next few days he took Gorm to art museums, gallery openings and story-telling sessions in his...

  14. The evolution of sex chromosomes in organisms with separate haploid sexes.

    Science.gov (United States)

    Immler, Simone; Otto, Sarah Perin

    2015-03-01

    The evolution of dimorphic sex chromosomes is driven largely by the evolution of reduced recombination and the subsequent accumulation of deleterious mutations. Although these processes are increasingly well understood in diploid organisms, the evolution of dimorphic sex chromosomes in haploid organisms (U/V) has been virtually unstudied theoretically. We analyze a model to investigate the evolution of linkage between fitness loci and the sex-determining region in U/V species. In a second step, we test how prone nonrecombining regions are to degeneration due to accumulation of deleterious mutations. Our modeling predicts that the decay of recombination on the sex chromosomes and the addition of strata via fusions will be just as much a part of the evolution of haploid sex chromosomes as in diploid sex chromosome systems. Reduced recombination is broadly favored, as long as there is some fitness difference between haploid males and females. The degeneration of the sex-determining region due to the accumulation of deleterious mutations is expected to be slower in haploid organisms because of the absence of masking. Nevertheless, balancing selection often drives greater differentiation between the U/V sex chromosomes than in X/Y and Z/W systems. We summarize empirical evidence for haploid sex chromosome evolution and discuss our predictions in light of these findings. © 2015 The Author(s).

  15. Neurogenin 3 Mediates Sex Chromosome Effects on the Generation of Sex Differences in Hypothalamic Neuronal Development

    Directory of Open Access Journals (Sweden)

    Maria Julia Scerbo

    2014-07-01

    Full Text Available The organizational action of testosterone during critical periods of development is the cause of numerous sex differences in the brain. However, sex differences in neuritogenesis have been detected in primary neuronal hypothalamic cultures prepared before the peak of testosterone production by fetal testis. In the present study we assessed the hypothesis of that cell-autonomous action of sex chromosomes can differentially regulate the expression of the neuritogenic gene neurogenin 3 (Ngn3 in male and female hypothalamic neurons, generating sex differences in neuronal development. Neuronal cultures were prepared from male and female E14 mouse hypothalami, before the fetal peak of testosterone. Female neurons showed enhanced neuritogenesis and higher expression of Ngn3 than male neurons. The silencing of Ngn3 abolished sex differences in neuritogenesis, decreasing the differentiation of female neurons. The sex difference in Ngn3 expression was determined by sex chromosomes, as demonstrated using the four core genotypes mouse model, in which a spontaneous deletion of the testis-determining gene Sry from the Y chromosome was combined with the insertion of the Sry gene onto an autosome. In addition, the expression of Ngn3, which is also known to mediate the neuritogenic actions of estradiol, was increased in the cultures treated with the hormone, but only in those from male embryos. Furthermore, the hormone reversed the sex differences in neuritogenesis promoting the differentiation of male neurons. These findings indicate that Ngn3 mediates both cell-autonomous actions of sex chromosomes and hormonal effects on neuritogenesis.

  16. Coder and decoder of fractal signals of comb-type structure

    Directory of Open Access Journals (Sweden)

    Politanskyi R. L.

    2014-08-01

    Full Text Available The article presents a coder and decoder of fractal signals of comb-type structure (FSCS based on microcontrollers (MC. The coder and decoder consist of identical control modules, while their managed modules have different schematic constructions. The control module performs forming or recognition of signals, and also carries out the function of information exchange with a computer. The basic element of the control module is a PIC18F2550 microcontroller from MicroChip. The coder of the system forms fractal signals of a given order according to the information bits coming from the computer. Samples of the calculated values of the amplitudes of elementary rectangular pulses that constitute the structure of fractal pulses are stored in the memory of the microcontroller as a table. Minimum bit capacity of the DAC necessary for the generation of FSCS of fourth order is four bits. The operation algorithm, "wired" into the controller of the program, provides for encoding of the transmitted information by two-bit symbols. Recognition of the start of transmission of each byte in communication channel is performed by the transmission of the timing signal. In a decoder the microcontroller carries out reception and decoding of the received fractal signals which are then transmitted to the computer. The developed algorithm of the program for the microcontroller of the decoder is carried out by determination of order of fractal impulse after the value of sum of amplitudes of elementary impulses, constituents fractal signal. The programs for coder and decoder are written in "C". In the most critical places of the program influencing on the fast-acting of chart “assembler” insertions are done. The blocks of the coder and decoder were connected with a coaxial 10 meters long cable with an impendance of 75 Ohm. The signals generated by the developed coder of FSCS, were studied using a digital oscillograph. On the basis of the obtained spectrums, it is possible

  17. Evidence for paralytic shellfish poisons in the freshwater cyanobacterium Lyngbya wollei (Farlow ex Gomont) comb. nov.

    Science.gov (United States)

    Carmichael, W W; Evans, W R; Yin, Q Q; Bell, P; Moczydlowski, E

    1997-08-01

    Lyngbya wollei (Farlow ex Gomont) comb. nov., a perennial mat-forming filamentous cyanobacterium prevalent in lakes and reservoirs of the southeastern United States, was found to produce a potent, acutely lethal neurotoxin when tested in the mouse bioassay. Signs of poisoning were similar to those of paralytic shellfish poisoning. As part of the Tennessee Valley Authority master plan for Guntersville Reservoir, the mat-forming filamentous cyanobacterium L. wollei, a species that had recently invaded from other areas of the southern United States, was studied to determine if it could produce any of the known cyanotoxins. Of the 91 field samples collected at 10 locations at Guntersville Reservoir, Ala., on the Tennessee River, over a 3-year period, 72.5% were toxic. The minimum 100% lethal doses of the toxic samples ranged from 150 to 1,500 mg kg of lyophilized L. wollei cells-1, with the majority of samples being toxic at 500 mg kg-1. Samples bioassayed for paralytic shellfish toxins by the Association of Official Analytical Chemists method exhibited saxitoxin equivalents ranging from 0 to 58 micrograms g (dry weight)-1. Characteristics of the neurotoxic compound(s), such as the lack of adsorption by C18 solid-phase extraction columns, the short retention times on C18 high-performance liquid chromatography (HPLC) columns, the interaction of the neurotoxins with saxiphilin (a soluble saxitoxin-binding protein), and external blockage of voltage-sensitive sodium channels, led to our discovery that this neurotoxin(s) is related to the saxitoxins, the compounds responsible for paralytic shellfish poisonings. The major saxitoxin compounds thus far identified by comparison of HPLC fluorescence retention times are decarbamoyl gonyautoxins 2 and 3. There was no evidence of paralytic shellfish poison C toxins being produced by L. wollei. Fifty field samples were placed in unialgal culture and grown under defined culture conditions. Toxicity and signs of poisoning for these

  18. Controlled generation of comb-like electron beams in plasma channels for polychromatic inverse Thomson γ-ray sources

    International Nuclear Information System (INIS)

    Kalmykov, S Y; Shadwick, B A; Davoine, X; Ghebregziabher, I; Lehe, R; Lifschitz, A F

    2016-01-01

    Propagating a relativistically intense, negatively chirped laser pulse (the bandwidth  >150 nm) in a plasma channel makes it possible to generate background-free, comb-like electron beams—sequences of synchronized bunches with a low phase-space volume and controlled energy spacing. The tail of the pulse, confined in the accelerator cavity (an electron density ‘bubble’), experiences periodic focusing, while the head, which is the most intense portion of the pulse, steadily self-guides. Oscillations of the cavity size cause periodic injection of electrons from the ambient plasma, creating an electron energy comb with the number of components, their mean energy, and energy spacing dependent on the channel radius and pulse length. These customizable electron beams enable the design of a tunable, all-optical source of pulsed, polychromatic γ-rays using the mechanism of inverse Thomson scattering, with up to  ∼10 −5 conversion efficiency from the drive pulse in the electron accelerator to the γ-ray beam. Such a source may radiate  ∼10 7 quasi-monochromatic photons per shot into a microsteradian-scale cone. The photon energy is distributed among several distinct bands, each having sub-30% energy spread, with a highest energy of 12.5 MeV. (paper)

  19. Genotoxicity, acute and subchronic toxicity studies in rats of a rooster comb extract rich in sodium hyaluronate.

    Science.gov (United States)

    Canut, Lourdes; Zapatero, Jorge; López, Sílvia; Torrent, Anna; Ruhí, Ramon; Vicente, Laura

    2012-04-01

    The toxicity of a rooster comb extract (IB0004) that contains mainly sodium hyaluronate was assessed in acute and subchronic studies and in a bacterial reverse mutation assay. In a single dose acute study, male and female rats were administered 2000 mg/kg body weight (bw) of the product and observed for 14 days. No mortality was recorded, thus it was considered that the minimum lethal dose for rats by oral route was greater than 2000 mg/kg bw. A 90-day subchronic study (5, 55 and 600 mg/kg bw/day, oral gavage) with 50 male and 50 female Wistar-Hannover rats produced no significant adverse effects on food consumption, body weight, mortality, clinical biochemistry, hematology, gross pathology, and histopathology. Although some differences were observed between the treated and control animals in body weight gain (%) and some hematological parameters, these changes were generally minor in nature and, are considered to be of no toxicological significance. The no-observable-adverse-effects level was established at 600 mg/kg bw/day. There was no evidence of mutagenic activity in Salmonella typhimurium TA98, TA100, TA1535 and TA1537 or in Escherichia coli WP2 uvra pkM101. In conclusion, the results from these safety studies support the safety of rooster comb extract IB0004 in food. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Investigating the interplay between mechanisms of anomalous diffusion via fractional Brownian walks on a comb-like structure

    International Nuclear Information System (INIS)

    Ribeiro, Haroldo V; Alves, Luiz G A; Zola, Rafael S; Lenzi, Ervin K; Tateishi, Angel A

    2014-01-01

    The comb model is a simplified description for anomalous diffusion under geometric constraints. It represents particles spreading out in a two-dimensional space where the motions in the x-direction are allowed only when the y coordinate of the particle is zero. Here, we propose an extension for the comb model via Langevin-like equations driven by fractional Gaussian noises (long-range correlated). By carrying out computer simulations, we show that the correlations in the y-direction affect the diffusive behavior in the x-direction in a non-trivial fashion, resulting in a quite rich diffusive scenario characterized by usual, superdiffusive or subdiffusive scaling of second moment in the x-direction. We further show that the long-range correlations affect the probability distribution of the particle positions in the x-direction, making their tails longer when noise in the y-direction is persistent and shorter for anti-persistent noise. Our model thus combines and allows the study/analysis of the interplay between different mechanisms of anomalous diffusion (geometric constraints and long-range correlations) and may find direct applications for describing diffusion in complex systems such as living cells. (paper)

  1. FRB 121102: A Repeatedly Combed Neutron Star by a Nearby Low-luminosity Accreting Supermassive Black Hole

    Science.gov (United States)

    Zhang, Bing

    2018-02-01

    The origin of fast radio bursts (FRBs) remains mysterious. Recently, the only repeating FRB source, FRB 121102, was reported to possess an extremely large and variable rotation measure (RM). The inferred magnetic field strength in the burst environment is comparable to that in the vicinity of the supermassive black hole Sagittarius A* of our Galaxy. Here, we show that all of the observational properties of FRB 121102 (including the high RM and its evolution, the high linear polarization degree, an invariant polarization angle across each burst and other properties previously known) can be interpreted within the “cosmic comb” model, which invokes a neutron star with typical spin and magnetic field parameters whose magnetosphere is repeatedly and marginally combed by a variable outflow from a nearby low-luminosity accreting supermassive black hole in the host galaxy. We propose three falsifiable predictions (periodic “on/off” states, and periodic/correlated variation of RM and polarization angle) of the model and discuss other FRBs within the context of the cosmic comb model as well as the challenges encountered by other repeating FRB models in light of the new observations.

  2. A low-fat yoghurt supplemented with a rooster comb extract on muscle joint function in adults with mild knee pain: a randomized, double blind, parallel, placebo-controlled, clinical trial of efficacy.

    Science.gov (United States)

    Solà, Rosa; Valls, Rosa-Maria; Martorell, Isabel; Giralt, Montserrat; Pedret, Anna; Taltavull, Núria; Romeu, Marta; Rodríguez, Àurea; Moriña, David; Lopez de Frutos, Victor; Montero, Manuel; Casajuana, Maria-Carmen; Pérez, Laura; Faba, Jenny; Bernal, Gloria; Astilleros, Anna; González, Roser; Puiggrós, Francesc; Arola, Lluís; Chetrit, Carlos; Martinez-Puig, Daniel

    2015-11-01

    Preliminary results suggested that oral-administration of rooster comb extract (RCE) rich in hyaluronic acid (HA) was associated with improved muscle strength. Following these promising results, the objective of the present study was to evaluate the effect of low-fat yoghurt supplemented with RCE rich in HA on muscle function in adults with mild knee pain; a symptom of early osteoarthritis. Participants (n = 40) received low-fat yoghurt (125 mL d(-1)) supplemented with 80 mg d(-1) of RCE and the placebo group (n = 40) consumed the same yoghurt without the RCE, in a randomized, controlled, double-blind, parallel trial over 12 weeks. Using an isokinetic dynamometer (Biodex System 4), RCE consumption, compared to control, increased the affected knee peak torque, total work and mean power at 180° s(-1), at least 11% in men (p < 0.05) with no differences in women. No dietary differences were noted. These results suggest that long-term consumption of low-fat yoghurt supplemented with RCE could be a dietary tool to improve muscle strength in men, associated with possible clinical significance. However, further studies are needed to elucidate reasons for these sex difference responses observed, and may provide further insight into muscle function.

  3. Sex: a sensitive issue.

    Science.gov (United States)

    1997-01-01

    Health care workers and educators may need to improve their skills in discussing sensitive issues in order to elicit and understand what influences people's attitudes toward sex. While the health worker may be bent upon preventing HIV infection, advising on family planning, or teaching youth about sexual relationships, his or her audience may have other priorities. A good counselor/teacher must learn what people's concerns are and discuss sexual health within that context. It can be difficult talking about sex because sex is a private concern and many people are embarrassed discussing it. Even sex partners often find it difficult to talk to each other about sex. Appropriate communication techniques vary depending upon the situation. It depends upon whether one is addressing people on an individual basis or in groups, which people are being addressed, which organization one is representing, and what one's role is. Good communication is a two-way sharing of information. The different stages of life, common beliefs and myths, culture and religion, relationships between men and women, reasons for having sex, and sex practices are discussed.

  4. Making Healthy Decisions About Sex

    Science.gov (United States)

    ... For Teens: How to Make Healthy Decisions About Sex Page Content Article Body Before you decide to ... alcohol or use drugs. Are You Ready for Sex? Sex can change your life and relationships. Having ...

  5. Dyspareunia: Painful Sex for Women

    Science.gov (United States)

    ... Safety Injury Rehabilitation Emotional Well-Being Mental Health Sex and Birth Control Sex and Sexuality Birth Control Family Health Infants and ... Share Print What is dyspareunia? Dyspareunia is painful sex for women. Also, it causes pain during tampon ...

  6. Hepatitis C: Sex and Sexuality

    Science.gov (United States)

    ... with Hepatitis » Sex and Sexuality: Entire Lesson Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... hepatitis C virus through sex. Can you pass hepatitis C to a sex partner? Yes, but it ...

  7. Terahertz Frequency-Domain Spectroscopy of Low-Pressure Acetonitrile Gas by a Photomixing Terahertz Synthesizer Referenced to Dual Optical Frequency Combs

    Science.gov (United States)

    Hsieh, Yi-Da; Kimura, Hiroto; Hayashi, Kenta; Minamikawa, Takeo; Mizutani, Yasuhiro; Yamamoto, Hirotsugu; Iwata, Tetsuo; Inaba, Hajime; Minoshima, Kaoru; Hindle, Francis; Yasui, Takeshi

    2016-09-01

    A terahertz (THz) frequency synthesizer based on photomixing of two near-infrared lasers with a sub-THz to THz frequency offset is a powerful tool for spectroscopy of polar gas molecules due to its broad spectral coverage; however, its frequency accuracy and resolution are relatively low. To tune the output frequency continuously and widely while maintaining its traceability to a frequency standard, we developed a photomixing THz synthesizer phase-locked to dual optical frequency combs (OFCs). While the phase-locking to dual OFCs ensured continuous tuning within a spectral range of 120 GHz, in addition to the traceability to the frequency standard, use of a broadband uni-traveling carrier photodiode for photomixing enabled the generation of CW-THz radiation within a frequency range from 0.2 to 1.5 THz. We demonstrated THz frequency-domain spectroscopy of gas-phase acetonitrile CH3CN and its isotope CH3 13CN in the frequency range of 0.600-0.720 THz using this THz synthesizer. Their rotational transitions were assigned with a frequency accuracy of 8.42 × 10-8 and a frequency resolution of 520 kHz. Furthermore, the concentration of the CH3CN gas at 20 Pa was determined to be (5.41 ± 0.05) × 1014 molecules/cm3 by curve fitting analysis of the measured absorbance spectrum, and the mixture ratio of the mixed CH3CN/CH3 13CN gas was determined to be 1:2.26 with a gas concentration of 1014-1015 molecules/cm3. The developed THz synthesizer is highly promising for high-precision THz-FDS of low-pressure molecular gases and will enable the qualitative and quantitative analyses of multiple gases.

  8. Characterization of the marine propionate-degrading, sulfate-reducing bacterium Desulfofaba fastidiosa sp. nov. and reclassification of Desulfomusa hansenii as Desulfofaba hansenii comb. nov.

    Science.gov (United States)

    Abildgaard, Lone; Ramsing, Niels Birger; Finster, Kai

    2004-03-01

    A rod-shaped, slightly curved sulfate reducer, designated strain P2(T), was isolated from the sulfate-methane transition zone of a marine sediment. Cells were motile by means of a single polar flagellum. The strain reduced sulfate, thiosulfate and sulfite to sulfide and used propionate, lactate and 1-propanol as electron donors. Strain P2(T) also grew by fermentation of lactate. Propionate was oxidized incompletely to acetate and CO(2). The DNA G+C content was 48.8 mol%. Sequence analysis of the small-subunit rDNA and the dissimilatory sulfite reductase gene revealed that strain P2(T) was related to the genera Desulfonema, Desulfococcus, Desulfosarcina, 'Desulfobotulus', Desulfofaba, Desulfomusa and Desulfofrigus. These genera include incomplete as well as complete oxidizers of substrates. Strain P2(T) shared important morphological and physiological traits with Desulfofaba gelida and Desulfomusa hansenii, including the ability to oxidize propionate incompletely to acetate. The 16S rRNA gene similarities of P2(T) to Desulfofaba gelida and Desulfomusa hansenii were respectively 92.9 and 91.5 %. Combining phenotypic and genotypic traits, we propose strain P2(T) to be a member of the genus Desulfofaba. The name Desulfofaba fastidiosa sp. nov. (type strain P2(T)=DSM 15249(T)=ATCC BAA-815(T)) is proposed, reflecting the limited number of substrates consumed by the strain. In addition, the reclassification of Desulfomusa hansenii as a member of the genus Desulfofaba, Desulfofaba hansenii comb. nov., is proposed. A common line of descent and a number of shared phenotypic traits support this reclassification.

  9. Sex, Deportation and Rescue

    DEFF Research Database (Denmark)

    Plambech, Sine

    2017-01-01

    recirculating the claim that human trafficking is the “third largest” criminal economy after drugs and weapons. Based on ethnographic fieldwork among Nigerian sex worker migrants conducted in Benin City, Nigeria, in 2011 and 2012, this study brings together four otherwise isolated migration economies......This contribution explores the economies interlinked by the migration of Nigerian women sex workers. The literature and politics of sex work migration and human trafficking economies are commonly relegated to the realm that focuses on profits for criminal networks and pimps, in particular...... – facilitation, remittances, deportation, and rescue – and suggests that we have to examine multiple sites and relink these in order to more fully understand the complexity of sex work migration. Drawing upon literature within transnational feminist analysis, critical human trafficking studies, and migration...

  10. Commentary Sex determination

    Indian Academy of Sciences (India)

    PRAKASH KUMAR G

    2008-01-31

    Jan 31, 2008 ... years old (Charnier 1966 reported it in an African agamid lizard), although it was ... people's attention in Susumu Ohno's now famous book on .... If they do enhance male and female fitness, sex chromosomes would then be.

  11. Commentary Sex determination

    Indian Academy of Sciences (India)

    PRAKASH KUMAR G

    2008-01-31

    ZW is reserved for female heterogamety.) The Radder et al study used lab incubation regimes that mimic temperature profiles of cool natural nests, so temperature probably determines sex at least occasionally in nature.

  12. Female Sex Tourism

    OpenAIRE

    Mc Intyre, Maria Kleivan

    2017-01-01

    ABSTRACT This project explores the phenomenon of North American and Western European women, who travel to the Global South and engage in sexual encounters with the local men. This project has positioned itself as a postcolonial critique, arguing that female sex tourism is a form of neocolonialism. It has also investigated the term romance tourism, where it has found that as a result of essentialist gender stereotyping, the female version of sex tourism has been titled ‘romance tourism’. The p...

  13. Sex and Horror

    OpenAIRE

    Jones, Steve

    2017-01-01

    The combination of sex and horror may be disquieting to many, but the two are natural (if perhaps gruesome) bedfellows. In fact, sex and horror coincide with such regularity in contemporary horror fiction that the two concepts appear to be at least partially intertwined. The sex–horror relationship is sometimes connotative rather than overt; examples of this relationship range from the seduction overtones of 'Nosferatu' and the juxtaposition of nudity and horror promised by European exploitat...

  14. Experimental identification of a comb-shaped chaotic region in multiple parameter spaces simulated by the Hindmarsh—Rose neuron model

    Science.gov (United States)

    Jia, Bing

    2014-03-01

    A comb-shaped chaotic region has been simulated in multiple two-dimensional parameter spaces using the Hindmarsh—Rose (HR) neuron model in many recent studies, which can interpret almost all of the previously simulated bifurcation processes with chaos in neural firing patterns. In the present paper, a comb-shaped chaotic region in a two-dimensional parameter space was reproduced, which presented different processes of period-adding bifurcations with chaos with changing one parameter and fixed the other parameter at different levels. In the biological experiments, different period-adding bifurcation scenarios with chaos by decreasing the extra-cellular calcium concentration were observed from some neural pacemakers at different levels of extra-cellular 4-aminopyridine concentration and from other pacemakers at different levels of extra-cellular caesium concentration. By using the nonlinear time series analysis method, the deterministic dynamics of the experimental chaotic firings were investigated. The period-adding bifurcations with chaos observed in the experiments resembled those simulated in the comb-shaped chaotic region using the HR model. The experimental results show that period-adding bifurcations with chaos are preserved in different two-dimensional parameter spaces, which provides evidence of the existence of the comb-shaped chaotic region and a demonstration of the simulation results in different two-dimensional parameter spaces in the HR neuron model. The results also present relationships between different firing patterns in two-dimensional parameter spaces.

  15. Experimental identification of a comb-shaped chaotic region in multiple parameter spaces simulated by the Hindmarsh—Rose neuron model

    International Nuclear Information System (INIS)

    Jia Bing

    2014-01-01

    A comb-shaped chaotic region has been simulated in multiple two-dimensional parameter spaces using the Hindmarsh—Rose (HR) neuron model in many recent studies, which can interpret almost all of the previously simulated bifurcation processes with chaos in neural firing patterns. In the present paper, a comb-shaped chaotic region in a two-dimensional parameter space was reproduced, which presented different processes of period-adding bifurcations with chaos with changing one parameter and fixed the other parameter at different levels. In the biological experiments, different period-adding bifurcation scenarios with chaos by decreasing the extra-cellular calcium concentration were observed from some neural pacemakers at different levels of extra-cellular 4-aminopyridine concentration and from other pacemakers at different levels of extra-cellular caesium concentration. By using the nonlinear time series analysis method, the deterministic dynamics of the experimental chaotic firings were investigated. The period-adding bifurcations with chaos observed in the experiments resembled those simulated in the comb-shaped chaotic region using the HR model. The experimental results show that period-adding bifurcations with chaos are preserved in different two-dimensional parameter spaces, which provides evidence of the existence of the comb-shaped chaotic region and a demonstration of the simulation results in different two-dimensional parameter spaces in the HR neuron model. The results also present relationships between different firing patterns in two-dimensional parameter spaces

  16. The effects of 595- and 1,064-nm lasers on rooster comb blood vessels using dual-wavelength and multipulse techniques.

    Science.gov (United States)

    Li, Guang; Sun, Jianfang; Shao, Xuebao; Sang, Honggui; Zhou, Zhanchao

    2011-10-01

    After laser irradiation, hemoglobin can transform into methemoglobin and coagulum, which have high absorptivity of near-infrared light. Sequential irradiation with 595 nm and 1,064 nm may be more effective than single wavelength to decrease residual vessel number in rooster combs. Six protocols (single pulse with 595 nm, double pulse with 595 nm, single pulse with 1,064 nm, double pulse with 1,064 nm, sequential irradiation with 595 nm and 1,064 nm (multiplex), and a blank control group) were used to compare the effects of sequential and single-wavelength irradiation on reducing residual vessel number, as well as the epidermal side effects, in the rooster comb. Different treatment techniques were applied to the same comb, at the same time. The treated areas of the epidermis and the residual vessels were observed using an optical microscope. All five techniques were effective in decreasing the number of residual vessels in the comb, and the side effects on the epidermis were similar for all. Considering the selectivity of the 595-nm laser and the rich melanin in the human epidermis, the dual-wavelength laser has a distinct advantage in treating vascular lesions. The authors have indicated no significant interest with commercial supporters. © 2011 by the American Society for Dermatologic Surgery, Inc.

  17. 38.2-Gb/s Optical-Wireless Transmission in 75-110 GHz Based on Electrical OFDM with Optical Comb Expansion

    DEFF Research Database (Denmark)

    Deng, Lei; Pang, Xiaodan; Beltrán, Marta

    2012-01-01

    We demonstrate scalable optical comb- and heterodyning-based generation, optical and 1.3-m wireless transmission, and electrical heterodyne detection of multiband OFDM up to 38.2 Gb/s occupying 14.4-GHz RF bandwidth, for high-capacity optical-wireless links in 75-110 GHz....

  18. Single-Source AlGaAs Frequency Comb Transmitter for 661 Tbit/s Data Transmission in a 30-core Fiber

    DEFF Research Database (Denmark)

    Hu, Hao; Da Ros, Francesco; Ye, Feihong

    2016-01-01

    We demonstrate an AlGaAs-on-insulator nano-waveguide-based frequency comb with high OSNR enabling a single-source to fully load a 9.6-km heterogeneous 30-core fibre with 661 Tbit/s data achieved by 30xcores, 80xWDM, 40 Gbaud, and PDM-16QAM...

  19. Altering the sex determination pathway in Drosophila fat body modifies sex-specific stress responses.

    Science.gov (United States)

    Argue, Kathryn J; Neckameyer, Wendi S

    2014-07-01

    The stress response in Drosophila melanogaster reveals sex differences in behavior, similar to what has been observed in mammals. However, unlike mammals, the sex determination pathway in Drosophila is well established, making this an ideal system to identify factors involved in the modulation of sex-specific responses to stress. In this study, we show that the Drosophila fat body, which has been shown to be important for energy homeostasis and sex determination, is a dynamic tissue that is altered in response to stress in a sex and time-dependent manner. We manipulated the sex determination pathway in the fat body via targeted expression of transformer and transformer-2 and analyzed these animals for changes in their response to stress. In the majority of cases, manipulation of transformer or transformer-2 was able to change the physiological output in response to starvation and oxidative stress to that of the opposite sex. Our data also uncover the possibility of additional downstream targets for transformer and transformer-2 that are separate from the sex determination pathway and can influence behavioral and physiological responses. Copyright © 2014 the American Physiological Society.

  20. Early Sex Work Initiation and Violence against Female Sex Workers in Mombasa, Kenya.

    Science.gov (United States)

    Parcesepe, Angela M; L'Engle, Kelly L; Martin, Sandra L; Green, Sherri; Suchindran, Chirayath; Mwarogo, Peter

    2016-12-01

    Between 20 and 40 % of female sex workers (FSWs) began sex work before age 18. Little is known concerning whether early initiation of sex work impacts later experiences in adulthood, including violence victimization. This paper examines the relationship between early initiation of sex work and violence victimization during adulthood. The sample included 816 FSWs in Mombasa, Kenya, recruited from HIV prevention drop-in centers who were 18 years or older and moderate-risk drinkers. Early initiation was defined as beginning sex work at 17 or younger. Logistic regression modeled recent violence as a function of early initiation, adjusting for drop-in center, age, education, HIV status, supporting others, and childhood abuse. Twenty percent of the sample reported early initiation of sex work. Although both early initiators and other FSWs reported commonly experiencing recent violence, early initiators were significantly more likely to experience recent physical and sexual violence and verbal abuse from paying partners. Early initiation was not associated with physical or sexual violence from non-paying partners. Many FSWs begin sex work before age 18. Effective interventions focused on preventing this are needed. In addition, interventions are needed to prevent violence against all FSWs, in particular, those who initiated sex work during childhood or adolescence.

  1. Sexing a sex-role-reversed species based on plumage: potential challenges in the red phalarope

    Directory of Open Access Journals (Sweden)

    Marie-Andrée Giroux

    2016-05-01

    Full Text Available Sex-role reversal, in which males care for offspring, can occur when mate competition is stronger between females than males. Secondary sex traits and mate attracting displays in sex-role-reversed species are usually more pronounced in females than in males. The red phalarope (Phalaropus fulicarius is a textbook example of a sex-role-reversed species. It is generally agreed that males are responsible for all incubation and parental care duties, whereas females typically desert males after having completed a clutch and may pair with new males to lay additional clutches. The breeding plumage of female red phalaropes is usually more brightly colored than male plumage, a reversed sexual dichromatism usually associated with sex-role reversal. Here, we confirm with PCR-based sexing that male red phalaropes can exhibit both the red body plumage typical of a female and the incubation behavior typical of a male. Our result, combined with previous observations of brightly colored red phalaropes incubating nests at the same arctic location (Igloolik Island, Nunavut, Canada, suggests that plumage dichromatism alone may not be sufficient to distinguish males from females in this breeding population of red phalaropes. This stresses the need for more systematic genetic sexing combined with standardized description of intersexual differences in red phalarope plumages. Determining whether such female-like plumage on males is a result of phenotypic plasticity or genetic variation could contribute to further understanding sex-role reversal strategies in the short Arctic summer.

  2. Beliefs About Sex and Parent-Child-Church Sex Communication Among Church-Based African American Youth.

    Science.gov (United States)

    Moore, Erin; Berkley-Patton, Jannette; Bohn, Alexandria; Hawes, Starlyn; Bowe-Thompson, Carole

    2015-10-01

    Parent-child sex communication has been shown to be protective against sexual risk among African American youth. The current study sought to use the theory of planned behavior as a framework for focus group discussions (N = 54 youth participants aged 12-19 years) to explore church youths' (a) sex beliefs and values (attitudes), (b) sources and evaluation of sex communication and education (subjective norms), (c) facilitator/barriers to adolescent sexual risk reduction and communication behaviors (perceived behavioral control), and (d) intentions to engage in these behaviors. Additionally, participants identified strategies for consideration in developing tailored parent-child-church sex communication education programs for use in African American churches. Themes suggested both positive and negative attitudes toward premarital sex and parents and churches as key sources of sex education and communication. Strategies to enhance parent-child-church sex communication are discussed in the context of these findings.

  3. Reclassification of Alcaligenes latus strains IAM 12599T and IAM 12664 and Pseudomonas saccharophila as Azohydromonas lata gen. nov., comb. nov., Azohydromonas australica sp. nov. and Pelomonas saccharophila gen. nov., comb. nov., respectively.

    Science.gov (United States)

    Xie, Cheng-Hui; Yokota, Akira

    2005-11-01

    The aim of this study was to clarify the taxonomic position of the nitrogen-fixing and hydrogen-oxidizing bacteria Alcaligenes latus strains IAM 12599T, IAM 12664 and IAM 12665 and Pseudomonas saccharophila IAM 14368T. It was found that the type strain of Alcaligenes latus, IAM 12599T, showed 99 x 9 and 96 x 1 % 16S rRNA gene sequence similarity to strains IAM 12665 and IAM 12664, respectively. A comparison using DNA-DNA hybridization suggested that strains IAM 12599T and IAM 12665 belong to a single species (89 x 7 %) and that strain IAM 12664 (35 x 1 %) forms a separate species. The phenotypic characteristics also support the conclusion that these bacteria should be identified as two species of a new genus: Azohydromonas lata gen. nov., comb. nov. (type strain IAM 12599T=DSM 1122T=LMG 3321T=ATCC 29712T; reference strain IAM 12665=DSM 1123=LMG 3325=ATCC 29714) and Azohydromonas australica sp. nov. (type strain IAM 12664T=DSM 1124T=LMG 3324T=ATCC 29713T). Pseudomonas saccharophila IAM 14368T was found to be closely related to the phototrophic bacterium Roseateles depolymerans, with 96 x 8 % 16S rRNA gene sequence similarity, but the two bacteria are quite different with respect to their metabolism and some significant phenotypic characteristics, suggesting that they cannot be included in a single genus. Further studies on their nifH gene sequences, G+C content of the DNA and cellular fatty acid composition confirm that Pseudomonas saccharophila should be reclassified: the name Pelomonas saccharophila gen. nov., comb. nov. is proposed, with the type strain IAM 14368T (=LMG 2256T=ATCC 15946T).

  4. Saccharolobus caldissimus gen. nov., sp. nov., a facultatively anaerobic iron-reducing hyperthermophilic archaeon isolated from an acidic terrestrial hot spring, and reclassification of Sulfolobus solfataricus as Saccharolobus solfataricus comb. nov. and Sulfolobus shibatae as Saccharolobus shibatae comb. nov.

    Science.gov (United States)

    Sakai, Hiroyuki D; Kurosawa, Norio

    2018-04-01

    A novel hyperthermophilic archaeon of strain HS-3 T , belonging to the family Sulfolobaceae, was isolated from an acidic terrestrial hot spring in Hakone Ohwaku-dani, Japan. Based on 16S rRNA gene sequence analysis, the closest phylogenetic relatives of strain HS-3 T were, first, Sulfolobus solfataricus (96.4 %) and, second, Sulfolobus shibatae (96.2 %), indicating that the strain belongs to the genus Sulfolobus. However, the sequence similarity to the type species of the genus Sulfolobus (Sulfolobus acidocaldarius) was remarkably low (91.8 %). In order to determine whether strain HS-3 T belongs to the genus Sulfolobus, its morphological, biochemical and physiological characteristics were examined in parallel with those of S. solfataricus and S. shibatae. Although there were some differences in chemolithotrophic growth between strain HS-3 T , S. solfataricus and S. shibatae, their temperature, pH and facultatively anaerobic characteristics of growth, and their utilization of various sugars were almost identical. In contrast, the utilization of various sugars by S. acidocaldarius was quite different from that of HS-3 T , S. solfataricus and S. shibatae. Phylogenetic evidence based on the 16S and the 23S rRNA gene sequences also clearly distinguished the monophyletic clade composed of strain HS-3 T , S. solfataricus, and S. shibatae from S. acidocaldarius. Based on these results, we propose a new genus and species, Saccharolobus caldissimus gen. nov., sp. nov., for strain HS-3 T , as well as two reclassifications, Saccharolobus solfataricus comb. nov. and Saccharolobus shibatae comb. nov. The type strain of Saccharolobus caldissimus is HS-3 T (=JCM 32116 T and InaCC Ar80 T ). The type species of the genus is Saccharolobus solfataricus.

  5. AIDS and sex tourism.

    Science.gov (United States)

    Herold, E S; Van Kerkwijk, C

    1992-01-01

    Tourists traveling internationally lower their inhibitions and take greater risks than they would typically in their home cultures. Loneliness, boredom, and a sense of freedom contribute to this behavioral change. Some tourists travel internationally in search of sexual gratification. This motivation may be actively conscious or subconscious to the traveler. Billed as romantic with great natural beauty, Thailand, the Philippines, Brazil, the Dominican Republic, and Kenya are popular destinations of tourists seeking sex. The Netherlands and countries in eastern Europe are also popular. With most initial cases of HIV infection in Europe having histories of international travel, mass tourism is a major factor in the international transmission of AIDS. While abroad, tourists have sex with casual partners, sex workers, and/or other tourists. Far from all tourists, however, carry and consistently use condoms with these partners. One study found female and non white travelers to be less likely than Whites and males to carry condoms. The risk of HIV infection increases in circumstances where condoms are not readily available in the host country and/or are of poor quality. Regarding actual condom use, a study found only 34% of sex tourists from Switzerland to consistently use condoms while abroad. 28% of men in an STD clinic in Melbourne, Australia, reported consistent condom use in sexual relations while traveling in Asia; STDs were identified in 73% of men examined. The few studies of tourists suggest that a significant proportion engage in risky behavior while traveling. HIV prevalence is rapidly increasing in countries known as destinations for sex tourism. High infection rates are especially evident among teenage sex workers in Thailand. Simply documenting the prevalence of risky behavior among sex tourists will not suffice. More research is needed on travelers and AIDS with particular attention upon the motivating factors supporting persistent high-risk behavior.

  6. Multiple sex-associated regions and a putative sex chromosome in zebrafish revealed by RAD mapping and population genomics.

    Directory of Open Access Journals (Sweden)

    Jennifer L Anderson

    Full Text Available Within vertebrates, major sex determining genes can differ among taxa and even within species. In zebrafish (Danio rerio, neither heteromorphic sex chromosomes nor single sex determination genes of large effect, like Sry in mammals, have yet been identified. Furthermore, environmental factors can influence zebrafish sex determination. Although progress has been made in understanding zebrafish gonad differentiation (e.g. the influence of germ cells on gonad fate, the primary genetic basis of zebrafish sex determination remains poorly understood. To identify genetic loci associated with sex, we analyzed F(2 offspring of reciprocal crosses between Oregon *AB and Nadia (NA wild-type zebrafish stocks. Genome-wide linkage analysis, using more than 5,000 sequence-based polymorphic restriction site associated (RAD-tag markers and population genomic analysis of more than 30,000 single nucleotide polymorphisms in our *ABxNA crosses revealed a sex-associated locus on the end of the long arm of chr-4 for both cross families, and an additional locus in the middle of chr-3 in one cross family. Additional sequencing showed that two SNPs in dmrt1 previously suggested to be functional candidates for sex determination in a cross of ABxIndia wild-type zebrafish, are not associated with sex in our AB fish. Our data show that sex determination in zebrafish is polygenic and that different genes may influence sex determination in different strains or that different genes become more important under different environmental conditions. The association of the end of chr-4 with sex is remarkable because, unique in the karyotype, this chromosome arm shares features with known sex chromosomes: it is highly heterochromatic, repetitive, late replicating, and has reduced recombination. Our results reveal that chr-4 has functional and structural properties expected of a sex chromosome.

  7. Attitudes Toward Same-Sex Parenting: An Effect of Gender.

    Science.gov (United States)

    Webb, Stephanie N; Chonody, Jill M; Kavanagh, Phillip S

    2017-01-01

    The definition of family in Australia has been continuously changing over the past four decades. The 21 st century has brought with it various images of family, with an increase of awareness to same-sex families; however, the acceptance of such family structures does not appear to be widespread and is often determined by sex. Substantive literature demonstrates differences between men and women in attitudes toward same-sex parenting, with theory suggesting that gender role norms may explain this. Despite large efforts to determine sex differences in attitudes toward same-sex parenting, little research, and even less in Australia, has been done to investigate whether there are differences in reasons behind negative attitudes toward same-sex parenting between men and women. To further this understanding, an Australian sample (N= 790) ranging in age from 18-78 completed a survey regrading attitudes toward same-sex parenting, in addition to relevant demographic information. Participants reported more positive attitudes about parenting by lesbians as compared to parenting by gay men. Reasons behind attitudes toward same-sex parenting also differed between males and females. Results suggested that the impact of socially prescribed gender norms may affect prejudice toward same-sex families. Despite an increase in tolerance for sexual minorities recently, policies that continue to discriminate against same-sex parenting rights demonstrates the importance of continuing to identify potential influences of same-sex family prejudice to reduce the potentially negative impacts associated with the prejudice.

  8. Clarification of Einfeldia Kieffer, 1922 (Diptera: Chironomidae) with E. australiensis (Freeman, 1961), comb. n. based on immature stages.

    Science.gov (United States)

    Cranston, Peter S; Martin, Jon; Mulder, Monica; Spies, Martin

    2016-08-31

    The immature stages are described for the first time for Chironomus (Xenochironomus) australiensis Freeman (Diptera: Chironomidae) and the adult male is redescribed including from type specimens. The species does not belong to Chironomus Meigen or Xenochironomus Kieffer, but is best placed in a modestly expanded Einfeldia Kieffer. Application of this genus name is clarified, including by a lectotype fixation for its type species, E. pectoralis Kieffer, 1924. Einfeldia australiensis (Freeman) comb. n. provides the first record of the genus from Australia; otherwise the genus is reported confidently only from North America, Central America and western Europe to Japan. The immature stages of E. australiensis occur in relatively shallow mesotrophic to eutrophic dune lakes and maars with circum-neutral pH and high conductivity, from southeastern Queensland to southern Australia. The cytology is described briefly from larval salivary glands. Alternative genus placements for the species are discussed, and problems with Einfeldia and connected systematics in the tribe Chironomini are addressed.

  9. Single- and Multiband OFDM Photonic Wireless Links in the 75−110 GHz Band Employing Optical Combs

    DEFF Research Database (Denmark)

    Beltrán, M.; Deng, Lei; Pang, Xiaodan

    2012-01-01

    , allowing the cost and energy efficiency of the system to be increased and supporting different users in the system. Four channels at 9.6 Gb/s/ch in 14.4-GHz bandwidth are generated and transmitted over up to 1.3-m wireless distance. The transmission of a 9.6-Gb/s single-channel signal occupying 3.2-GHz......The photonic generation of electrical orthogonal frequency-division multiplexing (OFDM) modulated wireless signals in the 75−110 GHz band is experimentally demonstrated employing in-phase/quadrature electrooptical modulation and optical heterodyn upconversion. The wireless transmission of 16......-quadrature-amplitude-modulation OFDM signals is demonstrated with a bit error rate performance within the forward error correction limits. Signals of 19.1 Gb/s in 6.3-GHz bandwidth are transmitted over up to 1.3-m wireless distance. Optical comb generation is further employed to support different channels...

  10. Moorea producens gen. nov., sp. nov. and Moorea bouillonii comb. nov., tropical marine cyanobacteria rich in bioactive secondary metabolites.

    Science.gov (United States)

    Engene, Niclas; Rottacker, Erin C; Kaštovský, Jan; Byrum, Tara; Choi, Hyukjae; Ellisman, Mark H; Komárek, Jiří; Gerwick, William H

    2012-05-01

    The filamentous cyanobacterial genus Moorea gen. nov., described here under the provisions of the International Code of Botanical Nomenclature, is a cosmopolitan pan-tropical group abundant in the marine benthos. Members of the genus Moorea are photosynthetic (containing phycocyanin, phycoerythrin, allophycocyanin and chlorophyll a), but non-diazotrophic (lack heterocysts and nitrogenase reductase genes). The cells (discoid and 25-80 µm wide) are arranged in long filaments (algae blooms and, due to morphological resemblance to the genus Lyngbya, this group has often been incorrectly cited in the literature. We here describe two species of the genus Moorea: Moorea producens sp. nov. (type species of the genus) with 3L(T) as the nomenclature type, and Moorea bouillonii comb. nov. with PNG5-198(R) as the nomenclature type.

  11. Phylogenetic and phenotypic characterisation of Sirococcus castaneae comb. nov. (synonym Diplodina castaneae), a fungal endophyte of European chestnut.

    Science.gov (United States)

    Meyer, Joana B; Trapiello, Estefanía; Senn-Irlet, Beatrice; Sieber, Thomas N; Cornejo, Carolina; Aghayeva, Dilzara; González, Ana J; Prospero, Simone

    2017-08-01

    In this paper we resolve the taxonomic status of the fungus Diplodina castaneae (Ascomycetes, Diaporthales, Gnomoniaceae) which occurs on the European chestnut (Castanea sativa) as endophyte and as the causal agent of Javart disease. Specimens from Switzerland, Spain, and Azerbaijan were sequenced at five nuclear loci (β-tubulin, EF-1α, ITS, LSU, and RPB2). Phylogenies were inferred to place D. castaneae in the Gnomoniaceae family. Moreover, growth rates and morphological characteristics on different agar media were assessed and compared to those of Gnomoniopsis castaneae, which can easily be confused with D. castaneae. Based on morphological and phylogenetic characteristics, we propose to reallocate D. castaneae to the genus Sirococcus, as S. castaneae comb. nov. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  12. Higher-order Peregrine combs and Peregrine walls for the variable-coefficient Lenells-Fokas equation

    Science.gov (United States)

    Wang, Zi-Qi; Wang, Xin; Wang, Lei; Sun, Wen-Rong; Qi, Feng-Hua

    2017-02-01

    In this paper, we study the variable-coefficient Lenells-Fokas (LF) model. Under large periodic modulations in the variable coefficients of the LF model, the generalized Akhmediev breathers develop into the breather multiple births (BMBs) from which we obtain the Peregrine combs (PCs). The PCs can be considered as the limiting case of the BMBs and be transformed into the Peregrine walls (PWs) with a specific amplitude of periodic modulation. We further investigate the spatiotemporal characteristics of the PCs and PWs analytically. Based on the second-order breather and rogue-wave solutions, we derive the corresponding higher-order structures (higher-order PCs and PWs) under proper periodic modulations. What is particularly noteworthy is that the second-order PC can be converted into the Peregrine pyramid which exhibits the higher amplitude and thickness. Our results could be helpful for the design of experiments in the optical fiber communications.

  13. Association between asthma and female sex hormones.

    Science.gov (United States)

    Baldaçara, Raquel Prudente de Carvalho; Silva, Ivaldo

    2017-01-01

    The relationship between sex hormones and asthma has been evaluated in several studies. The aim of this review article was to investigate the association between asthma and female sex hormones, under different conditions (premenstrual asthma, use of oral contraceptives, menopause, hormone replacement therapy and pregnancy). Narrative review of the medical literature, Universidade Federal do Tocantins (UFT) and Universidade Federal de São Paulo (Unifesp). We searched the CAPES journal portal, a Brazilian platform that provides access to articles in the MEDLINE, PubMed, SciELO, and LILACS databases. The following keywords were used based on Medical Subject Headings: asthma, sex hormones, women and use of oral contraceptives. The associations between sex hormones and asthma remain obscure. In adults, asthma is more common in women than in men. In addition, mortality due to asthma is significantly higher among females. The immune system is influenced by sex hormones: either because progesterone stimulates progesterone-induced blocking factor and Th2 cytokines or because contraceptives derived from progesterone and estrogen stimulate the transcription factor GATA-3. The associations between asthma and female sex hormones remain obscure. We speculate that estrogen fluctuations are responsible for asthma exacerbations that occur in women. Because of the anti-inflammatory action of estrogen, it decreases TNF-α production, interferon-γ expression and NK cell activity. We suggest that further studies that highlight the underlying physiopathological mechanisms contributing towards these interactions should be conducted.

  14. Teleology and Defining Sex.

    Science.gov (United States)

    Gamble, Nathan K; Pruski, Michal

    2018-07-01

    Disorders of sexual differentiation lead to what is often referred to as an intersex state. This state has medical, as well as some legal, recognition. Nevertheless, the question remains whether intersex persons occupy a state in between maleness and femaleness or whether they are truly men or women. To answer this question, another important conundrum needs to be first solved: what defines sex? The answer seems rather simple to most people, yet when morphology does not coincide with haplotypes, and genetics might not correlate with physiology the issue becomes more complex. This paper tackles both issues by establishing where the essence of sex is located and by superimposing that framework onto the issue of the intersex. This is achieved through giving due consideration to the biology of sexual development, as well as through the use of a teleological framework of the meaning of sex. Using a range of examples, the paper establishes that sex cannot be pinpointed to one biological variable but is rather determined by how the totality of one's biology is oriented towards biological reproduction. A brief consideration is also given to the way this situation could be comprehended from a Christian understanding of sex and suffering.

  15. Characterization of juvenile play in rats: importance of sex of self and sex of partner.

    Science.gov (United States)

    Argue, Kathryn J; McCarthy, Margaret M

    2015-01-01

    Juvenile social play is observed in many mammalian species, and its disruption in several neuropsychiatric disorders has greatly increased interest in understanding the origins and sources of variability in this behavior. We quantified social play behavior in juvenile rats and investigated the impact of sex and familiarity of the play partner. Sex differences in play behavior were investigated by comparing males and females from either same- or mixed-sex pairs with data pooled over 12 days of analysis. Whether play was altered based on the sex of the play partner was assessed using a paired analysis to compare play with a same- or opposite-sex play partner for both males and females. Additionally, a repeated measures design was utilized to determine whether play changed with increasing age. On postnatal day 33, a novel play partner was introduced. We used a repeated measures analysis to compare postnatal day 33 with the previous day. These approaches were used to assess the effects of age, sex, sex of partner, and familiarity of partner on total social play behavior as well as how play was broken down into components, such as pouncing, pinning, chasing, and boxing. There were sex differences in total frequency of play, and specific parameters of play behavior, such as chasing, pouncing, pinning, and boxing. Additionally, males significantly altered their play behavior in response to the sex of their play partner, whereas females were more sensitive to the familiarity of the play partner. This study provides critical groundwork for uncovering factors that regulate social play behavior and can be used to guide future mechanistic based work.

  16. Sex determination in mythology and history.

    Science.gov (United States)

    Mittwoch, Ursula

    2005-02-01

    The history of ideas on how the sexes became divided spans at least three thousand years. The biblical account of the origin of Eve, and the opinions of the philosophers of classical Greece, have unexpected bearings on present-day ideas. The scientific study of sex determination can be said to have begun in the 17th century with the discovery of spermatozoa, but the origin and function of the "spermatic animalcules" eluded investigators until 1841. The mammalian egg was discovered in 1827, and in the last quarter of the century fertilization was observed. The view current at that time, that sex determination was under environmental control, gave way to the idea of chromosomal determination in the first quarter of the 20th century. The study of human and other mammalian chromosomes during the third quarter of the century, and the discovery of sex-chromosome abnormalities, emphasized the importance of the Y chromosome for male sex determination. The last quarter of the century witnessed a hunt for the "testis-determining" gene, thought to be responsible for the differentiation of Sertoli cells, and culminating in the isolation of SRY (Sry in the mouse). However, an increasing number of additional genes and growth factors were found to be required for the establishment of male sex. During the same period evidence emerged that male development was accompanied by enhanced growth, both of gonads and whole embryos. An unexpected finding was the demonstration of temperature-dependent sex determination in reptiles. With the advent of the 21st century, it was shown that Sry induces cell proliferation in fetal mouse gonads, and it has been suggested that male sex differentiation in mammals requires a higher metabolic rate. These insights could lead to a better understanding and improved treatment of abnormalities of sexual development.

  17. Parent-adolescent sex communication in China.

    Science.gov (United States)

    Zhang, Liying; Li, Xiaoming; Shah, Iqbal H; Baldwin, Wendy; Stanton, Bonita

    2007-06-01

    Communication concerning sexual matters between parents and their adolescent children serve as a protective factor and exerts a favourable influence on adolescents' sexual behaviours. As limited data regarding parent-adolescent sex communication are available in China, this study was undertaken with the aim of exploring the patterns and related factors of such communication and its relationship with adolescent sexual behaviour. Community-based data were collected in 2001 in Changchun, China. Unmarried adolescents 15-19 years of age (322 young men and 360 young women) were included in a survey using self-administered questionnaires. Overall, sex communication with parents was relatively infrequent. There was a significant gender difference in the pattern of sex communication, with male adolescents being more likely to talk with fathers and female adolescents with mothers. Logistic regression analysis revealed that gender of adolescents, quality of communication with mothers on general topics, and adolescent's perception of mother being the main source of sex knowledge were predictive of the level of sex communication between mother and her adolescent children. This study reveals that communication regarding sexual matters between parents and adolescents was limited in China. The quality of communication on general topics between parents and their adolescent children is one of the important factors related to sex communication between them. It is essential that Chinese parents are better informed and skilled to be involved, in addition to school and community, in the sex education of their adolescent children. They should be able to communicate appropriately on sex-related issues with them.

  18. Same sex families and children

    OpenAIRE

    Mršević Zorica

    2009-01-01

    Introduction comprises the information on two main forms of same sex families, civic partnership (same sex partnership) and same sex marriage. Countries and various status modalities of legal regulations are mentioned. The main part of the text is dedicated to presentation of the findings of the most recent research on various aspects regarding children of same sex partnerships. It comprises presentations grouped in four main chapters: acceptance of same sex partnerships, acceptance of legal ...

  19. Sex Hormones and Tendon

    DEFF Research Database (Denmark)

    Hansen, Mette; Kjaer, Michael

    2016-01-01

    The risk of overuse and traumatic tendon and ligament injuries differ between women and men. Part of this gender difference in injury risk is probably explained by sex hormonal differences which are specifically distinct during the sexual maturation in the teenage years and during young adulthood....... The effects of the separate sex hormones are not fully elucidated. However, in women, the presence of estrogen in contrast to very low estrogen levels may be beneficial during regular loading of the tissue or during recovering after an injury, as estrogen can enhance tendon collagen synthesis rate. Yet...... has also been linked to a reduced responsiveness to relaxin. The present chapter will focus on sex difference in tendon injury risk, tendon morphology and tendon collagen turnover, but also on the specific effects of estrogen and androgens....

  20. Invited review: sex ratio and rheumatic disease.

    Science.gov (United States)

    Lockshin, M D

    2001-11-01

    Human illnesses affect men and women differently. In some cases (diseases of sex organs, diseases resulting from X or Y chromosome mutations), reasons for sex discrepancy are obvious, but in other cases no reason is apparent. Explanations for sex discrepancy of illness occur at different biological levels: molecular (e.g., imprinting, X-inactivation), cellular (sex-specific receptor activity), organ (endocrine influences), whole organism (size, age), and environmental-behavioral, including intrauterine influences. Autoimmunity represents a prototypical class of illness that has high female-to-male (F/M) ratios. Although the F/M ratios in autoimmune diseases are usually attributed to the influence of estrogenic hormones, evidence demonstrates that the attributed ratios are imprecise and that definitions and classifications of autoimmune diseases vary, rendering at least part of the counting imprecise. In addition, many studies on sex discrepancy of human disease fail to distinguish between disease incidence and disease severity. In April 2001, the Institute of Medicine of the National Academy of Sciences published Exploring the Biological Contributions to Human Health: Does Sex Matter? (Wizemann T and Pardue M-L, editors). This minireview summarizes the section of that report that concerns autoimmune and infectious disease. Some thyroid, rheumatic, and hepatic autoimmune diseases have high F/M ratios, whereas others have low. Those that have high ratios occur primarily in young adulthood. Gonadal hormones, if they play a role, likely do so through a threshold or permissive mechanism. Examples of sex differences that could be caused by environmental exposure, X inactivation, imprinting, X or Y chromosome genetic modulators, and intrauterine influences are presented as alternate, theoretical, and largely unexplored explanations for sex differences of incidence. The epidemiology of autoimmune diseases (young, female) suggests that an explanation for sex discrepancy of

  1. Sex Disparities in Stroke

    DEFF Research Database (Denmark)

    Dehlendorff, Christian; Andersen, Klaus Kaae; Olsen, Tom Skyhøj

    2015-01-01

    between 2003 and 2012 (N=79 617), and the Danish Register of Causes of Death. Information was available on age, sex, marital status, stroke severity, stroke subtype, socioeconomic status, and cardiovascular risk profile. We studied only deaths due to the index stroke, with the assumption that death.......5%) or 1 month (6.9%), respectively. After the age of 60 years, women had more severe strokes than men. Up to ages in the mid-60s, no difference in the risk of death from stroke was seen between the 2 sexes. For people aged >65 years, however, the risk gradually became greater in men than in women...

  2. Sex steroids and neurogenesis.

    Science.gov (United States)

    Heberden, Christine

    2017-10-01

    The brain has long been known as a dimorphic organ and as a target of sex steroids. It is also a site for their synthesis. Sex steroids in numerous ways can modify cerebral physiology, and along with many processes adult neurogenesis is also modulated by sex steroids. This review will focus on the effects of the main steroids, estrogens, androgens and progestogens, and unveil some aspects of their partly disclosed mechanisms of actions. Gonadal steroids act on different steps of neurogenesis: cell proliferation seems to be increased by estrogens only, while androgens and progestogens favor neuronal renewal by increasing cell survival; differentiation is a common target. Aging is characterized by a cognitive deficiency, paralleled by a decrease in the rate of neuronal renewal and in the levels of circulating gonadal hormones. Therefore, the effects of gonadal hormones on the aging brain are important to consider. The review will also be expanded to related molecules which are agonists to the nuclear receptors. Sex steroids can modify adult neuronal renewal and the extensive knowledge of their actions on neurogenesis is essential, as it can be a leading pathway to therapeutic perspectives. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. How Sex Attitudes Develop

    Science.gov (United States)

    Arnstein, Helene S.

    1976-01-01

    Excerpt from "The Roots of Love" (Helene S. Arnstein, 1975). Book is concerned with feelings that are part of child's developmental stages. Included in excerpt are: genital self-discovery, masturbation, discovery of sex differences, and birth fantasies. Stresses importance of parent's feelings which are communicated to child.

  4. Sex differences in addiction.

    Science.gov (United States)

    Becker, Jill B

    2016-12-01

    Women exhibit more rapid escalation from casual drug taking to addiction, exhibit a greater withdrawal response with abstinence, and tend to exhibit greater vulnerability than men in terms of treatment outcome. In rodents, short-term estradiol intake in female rats enhances acquisition and escalation of drug taking, motivation for drugs of abuse, and relapse-like behaviors. There is also a sex difference in the dopamine response in the nucleus accumbens. Ovariectomized female rats exhibit a smaller initial dopamine increase after cocaine treatment than castrated males. Estradiol treatment of ovariectomized female rats enhances stimulated dopamine release in the dorsolateral striatum, but not in the nucleus accumbens, resulting in a sex difference in the balance between these two dopaminergic projections. In the situation where drug-taking behavior becomes habitual, dopamine release has been reported to be enhanced in the dorsolateral striatum and attenuated in the nucleus accumbens. The sex difference in the balance between these neural systems is proposed to underlie sex differences in addiction.

  5. Battle of the Sexes

    NARCIS (Netherlands)

    Bulte, E.H.; Tu, Q.; List, J.

    2015-01-01

    A vibrant literature has emerged that explores the economic implications of the sex ratio (the ratio of men to women in the population), including changes in fertility rates, educational outcomes, labor supply, and household purchases. Previous empirical efforts, however, have paid less attention to

  6. Sex education and ideals

    NARCIS (Netherlands)

    de Ruyter, D.J.; Spiecker, B.

    2008-01-01

    This article argues that sex education should include sexual ideals. Sexual ideals are divided into sexual ideals in the strict sense and sexual ideals in the broad sense. It is argued that ideals that refer to the context that is deemed to be most ideal for the gratification of sexual ideals in the

  7. Phylogenetic evaluation of Geomyces and allies reveals no close relatives of Pseudogymnoascus destructans, comb. nov., in bat hibernacula of eastern North America.

    Science.gov (United States)

    Minnis, Andrew M; Lindner, Daniel L

    2013-09-01

    hygrophilum, comb. nov., in accordance with the one name per fungus system of classification, and two additional combinations are made in Pseudogymnoascus including Pseudogymnoascus carnis and Pseudogymnoascus pannorum. Additional sampling from other regions of the world is needed to better understand the evolution and biogeography of this important and diverse group of fungi. Published by Elsevier Ltd.

  8. Sex education in Cyprus.

    Science.gov (United States)

    Patsalides, N

    1991-05-01

    The objective of educating people on family planning and sexuality issues has been carried forth by the Family Planning Association of Cyprus (FPAC) since 1971. The promotion of sex education in schools has generated respect for their expertise. Sex education has reached the agenda of the General Assembly of Parliament only to be postponed due to the April 1991 end of term dismissal. A newly elected Parliament are not expected to act immediately. The Ministry of Education Committee on Health Education has been actively counseled since 1974, and most recently in their examination of the possibilities of school sex education and training of high school teachers. The Ministry of Education has authority over primary and secondary education, which is compulsory up to 3 years of secondary education. The approach of FPAC has been to work with parents first in education lectures at various well publicized locations. The agenda was to inform about FPAC, explain the purpose and meaning of sex education, and show the Merry-Go-Round educational film followed by a question and answer session. Eventually, presentations involved children with parent observation. In 1977, authorization from the Ministry of Education gave official approval to FPAC, but not on school premises. FPAC went directly to headmasters and gained support in primary schools to organize sessions on school premises, which successfully involved many primary schools even in the much needed rural areas. Home Economics and Child Care, offered in the 5th and 6th grades was the only vehicle for gaining permission to enter secondary schools. In Larnaca, secondary school headmasters at the 3rd and 6th grade levels permitted invitations which requested parental permission. Lecture topics on human reproduction, sex roles, and disease and contraception were also provided in a follow-up letter. Higher education levels were involved through youth clubs and evening lectures. In 1988, FPAC urged the Director General of the

  9. Sex and life expectancy.

    Science.gov (United States)

    Seifarth, Joshua E; McGowan, Cheri L; Milne, Kevin J

    2012-12-01

    A sexual dimorphism in human life expectancy has existed in almost every country for as long as records have been kept. Although human life expectancy has increased each year, females still live longer, on average, than males. Undoubtedly, the reasons for the sex gap in life expectancy are multifaceted, and it has been discussed from both sociological and biological perspectives. However, even if biological factors make up only a small percentage of the determinants of the sex difference in this phenomenon, parity in average life expectancy should not be anticipated. The aim of this review is to highlight biological mechanisms that may underlie the sexual dimorphism in life expectancy. Using PubMed, ISI Web of Knowledge, and Google Scholar, as well as cited and citing reference histories of articles through August 2012, English-language articles were identified, read, and synthesized into categories that could account for biological sex differences in human life expectancy. The examination of biological mechanisms accounting for the female-based advantage in human life expectancy has been an active area of inquiry; however, it is still difficult to prove the relative importance of any 1 factor. Nonetheless, biological differences between the sexes do exist and include differences in genetic and physiological factors such as progressive skewing of X chromosome inactivation, telomere attrition, mitochondrial inheritance, hormonal and cellular responses to stress, immune function, and metabolic substrate handling among others. These factors may account for at least a part of the female advantage in human life expectancy. Despite noted gaps in sex equality, higher body fat percentages and lower physical activity levels globally at all ages, a sex-based gap in life expectancy exists in nearly every country for which data exist. There are several biological mechanisms that may contribute to explaining why females live longer than men on average, but the complexity of the

  10. The Influence of Sex Information on Gender Word Processing.

    Science.gov (United States)

    Casado, Alba; Palma, Alfonso; Paolieri, Daniela

    2018-06-01

    Three different tasks (word repetition, lexical decision, and gender decision) were designed to explore the impact of the sex clues (sex of the speaker, sex of the addressee) and the type of gender (semantic, arbitrary) on the processing of isolated Spanish gendered words. The findings showed that the grammatical gender feature was accessed when no mandatory attentional focus was required. In addition, the results indicated that the participants organize information according to their own sex role, which provides more salience to the words that match in grammatical gender with their own sex role representation, even when the gender assignment is arbitrary. Finally, the sex of the speaker biased the lexical access and the grammatical gender selection, serving as a semantic prime when the two dimensions have a congruent relationship. Furthermore, the masculine form serves as the generic gender representing both male and female figures.

  11. Sex guilt and life satisfaction in Iranian-american women.

    Science.gov (United States)

    Abdolsalehi-Najafi, Emon; Beckman, Linda J

    2013-08-01

    Although the experience of sex guilt has been considered among a variety of ethnic groups, the area has not yet been empirically explored among Iranian American women. The present study investigated the relationship between sexual self-schema (i.e., beliefs about the sexual aspects of oneself), acculturation, and sex guilt, and it further examined the association between sex guilt and life satisfaction in Iranian American women. A total of 65 Iranian American women, with a mean age of 31.3 years (SD = 11.7), completed five self-administered questionnaires. Findings indicated a significant inverse correlation between sexual self-schema and sex guilt. More specifically, women who endorsed negative self-views regarding their sexual self reported higher levels sex guilt. Results revealed that acculturation was unrelated to sex guilt, when the effect of being Muslim or non-Muslim was controlled. Women with high sex guilt reported significantly lower levels of life satisfaction. Moreover, analyses for mediation effects supported sex guilt as a partially mediating variable between sexual self-schema and life satisfaction. Levels of sex guilt were higher among Muslim women when compared to women of other religious affiliations. Additionally, Muslim women appeared to be significantly less acculturated to Western ideals than other religious groups. The present findings suggest that mental health professionals who provide services to Iranian American women need to consider the negative effects of sex guilt, particularly among Muslim women.

  12. Reclassification of Bacillus beijingensis Qiu et al. 2009 and Bacillus ginsengi Qiu et al. 2009 as Bhargavaea beijingensis comb. nov. and Bhargavaea ginsengi comb. nov. and emended description of the genus Bhargavaea.

    Science.gov (United States)

    Verma, Pankaj; Pandey, Prashant Kumar; Gupta, Arvind Kumar; Seong, Chi Nam; Park, Seong Chan; Choe, Han Na; Baik, Keun Sik; Patole, Milind Shivaji; Shouche, Yogesh Shreepad

    2012-10-01

    and Bacillus ginsengi to the genus Bhargavaea, as Bhargavaea beijingensis comb. nov. (type strain ge10(T)  = DSM 19037(T)  = CGMCC 1.6762(T)) and Bhargavaea ginsengi comb. nov. (type strain ge14(T)  = DSM 19038(T)  = CGMCC 1.6763(T)).

  13. Cerebral sex dimorphism and sexual orientation.

    Science.gov (United States)

    Manzouri, Amirhossein; Savic, Ivanka

    2018-03-01

    The neurobiology of sexual orientation is frequently discussed in terms of cerebral sex dimorphism (defining both functional and structural sex differences). Yet, the information about possible cerebral differences between sex-matched homo and heterosexual persons is limited, particularly among women. In this multimodal MRI study, we addressed these issues by investigating possible cerebral differences between homo and heterosexual persons, and by asking whether there is any sex difference in this aspect. Measurements of cortical thickness (Cth), subcortical volumes, and functional and structural resting-state connections among 40 heterosexual males (HeM) and 40 heterosexual females (HeF) were compared with those of 30 homosexual males (HoM) and 30 homosexual females (HoF). Congruent with previous reports, sex differences were detected in heterosexual controls with regard to fractional anisotropy (FA), Cth, and several subcortical volumes. Homosexual groups did not display any sex differences in FA values. Furthermore, their functional connectivity was significantly less pronounced in the mesial prefrontal and precuneus regions. In these two particular regions, HoM also displayed thicker cerebral cortex than other groups, whereas HoF did not differ from HeF. In addition, in HoM the parietal Cth showed "sex-reversed" values, not observed in HoF. Homosexual orientation seems associated with a less pronounced sexual differentiation of white matter tracts and a less pronounced functional connectivity of the self-referential networks compared to heterosexual orientation. Analyses of Cth suggest that male and female homosexuality are not simple analogues of each other and that differences from heterosexual controls are more pronounced in HoM. © 2017 Wiley Periodicals, Inc.

  14. Disestablishing Sex: The Case for Released-Time Sex Education

    Science.gov (United States)

    Glanzer, Perry L.

    2011-01-01

    Allowing nonschool organizations to provide sex education in a released-time format would disestablish state-funded sex education and give families a choice in the sex education that would be provided for their children. Released-time programs, as originally conceived and currently practiced, allow students to be released for a period of time…

  15. Sex identification of Nigerian indigenous chicks using Auto-sexing ...

    African Journals Online (AJOL)

    Sexing has been a challenging task in Nigerian indigenous chickens due to the monomorphism of chicks which makes it impossible to distinguish the male from the female until eight weeks. . Therefore, this study was carried out to determine the sex of Nigerian indigenous chicks using the common auto-sexing methods.

  16. Additive Manufacturing Infrared Inspection

    Science.gov (United States)

    Gaddy, Darrell; Nettles, Mindy

    2015-01-01

    The Additive Manufacturing Infrared Inspection Task started the development of a real-time dimensional inspection technique and digital quality record for the additive manufacturing process using infrared camera imaging and processing techniques. This project will benefit additive manufacturing by providing real-time inspection of internal geometry that is not currently possible and reduce the time and cost of additive manufactured parts with automated real-time dimensional inspections which deletes post-production inspections.

  17. High power frequency comb based on mid-infrared quantum cascade laser at λ ∼ 9 μm

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Q. Y.; Razeghi, M., E-mail: razeghi@eecs.northwestern.edu; Slivken, S.; Bandyopadhyay, N.; Bai, Y.; Zhou, W. J.; Chen, M.; Heydari, D.; Haddadi, A.; McClintock, R. [Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208 (United States); Amanti, M.; Sirtori, C. [Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Diderot and CNRS, UMR7162, 75205 Paris (France)

    2015-02-02

    We investigate a frequency comb source based on a mid-infrared quantum cascade laser at λ ∼ 9 μm with high power output. A broad flat-top gain with near-zero group velocity dispersion has been engineered using a dual-core active region structure. This favors the locking of the dispersed Fabry-Pérot modes into equally spaced frequency lines via four wave mixing. A current range with a narrow intermode beating linewidth of 3 kHz is identified with a fast detector and spectrum analyzer. This range corresponds to a broad spectral coverage of 65 cm{sup −1} and a high power output of 180 mW for ∼176 comb modes.

  18. High power frequency comb based on mid-infrared quantum cascade laser at λ ∼ 9 μm

    International Nuclear Information System (INIS)

    Lu, Q. Y.; Razeghi, M.; Slivken, S.; Bandyopadhyay, N.; Bai, Y.; Zhou, W. J.; Chen, M.; Heydari, D.; Haddadi, A.; McClintock, R.; Amanti, M.; Sirtori, C.

    2015-01-01

    We investigate a frequency comb source based on a mid-infrared quantum cascade laser at λ ∼ 9 μm with high power output. A broad flat-top gain with near-zero group velocity dispersion has been engineered using a dual-core active region structure. This favors the locking of the dispersed Fabry-Pérot modes into equally spaced frequency lines via four wave mixing. A current range with a narrow intermode beating linewidth of 3 kHz is identified with a fast detector and spectrum analyzer. This range corresponds to a broad spectral coverage of 65 cm −1 and a high power output of 180 mW for ∼176 comb modes

  19. Adsorption and combing of DNA on HOPG surfaces of bulk crystals and nanosheets: application to the bridging of DNA between HOPG/Si heterostructures

    International Nuclear Information System (INIS)

    Rose, F; Martin, P; Fujita, H; Kawakatsu, H

    2006-01-01

    Controlled and reproducible combing of λ-phage DNA molecules can be realized in predetermined orientations on highly oriented pyrolitic graphite (HOPG) surfaces. Observations by atomic force microscopy (AFM) show that DNA adsorption onto HOPG surfaces leads to different hierarchical organizations such as balls, networks, films, and fractal structures. HOPG nanosheets (3.5-100 nm thick) were created by simply rubbing a HOPG crystal onto a silicon oxide surface, and then patterned with a focused ion beam (FIB) to fabricate HOPG/Si heterostructures (arrays of silicon micropillars and microtracks decorated on their top surface with HOPG nanosheets). The surface reactivity of HOPG nanosheets toward DNA is found to be the same as of HOPG bulk crystals. Finally, combing is used to attach and suspend bundles of approximately 20-50 DNA molecules between HOPG/Si heterostructures

  20. Tunable optical frequency comb enabled scalable and cost-effective multiuser orthogonal frequency-division multiple access passive optical network with source-free optical network units.

    Science.gov (United States)

    Chen, Chen; Zhang, Chongfu; Liu, Deming; Qiu, Kun; Liu, Shuang

    2012-10-01

    We propose and experimentally demonstrate a multiuser orthogonal frequency-division multiple access passive optical network (OFDMA-PON) with source-free optical network units (ONUs), enabled by tunable optical frequency comb generation technology. By cascading a phase modulator (PM) and an intensity modulator and dynamically controlling the peak-to-peak voltage of a PM driven signal, a tunable optical frequency comb source can be generated. It is utilized to assist the configuration of a multiple source-free ONUs enhanced OFDMA-PON where simultaneous and interference-free multiuser upstream transmission over a single wavelength can be efficiently supported. The proposed multiuser OFDMA-PON is scalable and cost effective, and its feasibility is successfully verified by experiment.

  1. Transition dipole-moment of the ν1 +ν3 band of acetylene measured with dual-comb Fourier-transform spectroscopy

    Science.gov (United States)

    Okubo, Sho; Iwakuni, Kana; Yamada, Koichi M. T.; Inaba, Hajime; Onae, Atsushi; Hong, Feng-Lei; Sasada, Hiroyuki

    2017-11-01

    The ν1 +ν3 vibration band of acetylene (C2H2) in the near infrared region was recorded with a dual-comb Fourier-transform spectrometer. We observed 56 transitions from P (26) to R (29) at six different column densities. The integral line intensity was determined for each recorded absorption line by fitting the line profile to Lambert-Beer's law with a Voigt function. Thanks to the outstanding capability of dual-comb spectroscopy to cover a broad spectrum in a relatively short time with high resolution and high frequency precision, we determined the reliable line strength for each ro-vibrational transition as well as the transition dipole moment for this band.

  2. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Cord Injury Medical Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries ... Coping with a New Injury Robin Dorman, PsyD Sex and Fertility After Spinal Cord Injury Diane M. ...

  3. Sex and Fertility After SCI

    Science.gov (United States)

    ... Cord Injury Medical Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries ... Coping with a New Injury Robin Dorman, PsyD Sex and Fertility After Spinal Cord Injury Diane M. ...

  4. Low Sex Drive in Women

    Science.gov (United States)

    Low sex drive in women Overview Women's sexual desires naturally fluctuate over the years. Highs and lows commonly coincide ... used for mood disorders also can cause low sex drive in women. If your lack of interest ...

  5. SHBG (Sex Hormone Binding Globulin)

    Science.gov (United States)

    ... Links Patient Resources For Health Professionals Subscribe Search Sex Hormone Binding Globulin (SHBG) Send Us Your Feedback ... As Testosterone-estrogen Binding Globulin TeBG Formal Name Sex Hormone Binding Globulin This article was last reviewed ...

  6. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... Medical Expert Videos Topics menu Topics Sex and Fertility After Spinal Cord Injury Adult Injuries Spinal Cord ... a New Injury Robin Dorman, PsyD Sex and Fertility After Spinal Cord Injury Diane M. Rowles, MS, ...

  7. Sex and Fertility After SCI

    Medline Plus

    Full Text Available ... sex after a spinal cord injury? play_arrow Can men and women still have sex after a ... menstruation after a spinal cord injury? play_arrow Can women still get pregnant after a spinal cord ...

  8. Hypnotic Psychotherapy with Sex Offenders

    Science.gov (United States)

    Moseley, Sullivan; Briggs, Wanda P.; Magnus, Virginia

    2005-01-01

    The authors review the literature on the prevalence of sex offenders; multiple treatment modalities; and implications of the use of hypnotic psychotherapy, coupled with cognitive behavioral treatment programs, for treating sex offenders. (Contains 2 tables.)

  9. Phase-locking of a 2.5 THz quantum cascade laser to a frequency comb using a GaAs photomixer.

    Science.gov (United States)

    Ravaro, M; Manquest, C; Sirtori, C; Barbieri, S; Santarelli, G; Blary, K; Lampin, J-F; Khanna, S P; Linfield, E H

    2011-10-15

    We report the heterodyne detection and phase locking of a 2.5 THz quantum cascade laser (QCL) using a terahertz frequency comb generated in a GaAs photomixer using a femtosecond fiber laser. With 10 mW emitted by the QCL, the phase-locked signal at the intermediate frequency yields 80 dB of signal-to-noise ratio in a bandwidth of 1 Hz.

  10. Djebelemur, a tiny pre-tooth-combed primate from the Eocene of Tunisia: a glimpse into the origin of crown strepsirhines.

    Directory of Open Access Journals (Sweden)

    Laurent Marivaux

    Full Text Available BACKGROUND: Molecular clock estimates of crown strepsirhine origins generally advocate an ancient antiquity for Malagasy lemuriforms and Afro-Asian lorisiforms, near the onset of the Tertiary but most often extending back to the Late Cretaceous. Despite their inferred early origin, the subsequent evolutionary histories of both groups (except for the Malagasy aye-aye lineage exhibit a vacuum of lineage diversification during most part of the Eocene, followed by a relative acceleration in diversification from the late Middle Eocene. This early evolutionary stasis was tentatively explained by the possibility of unrecorded lineage extinctions during the early Tertiary. However, this prevailing molecular view regarding the ancient origin and early diversification of crown strepsirhines must be viewed with skepticism due to the new but still scarce paleontological evidence gathered in recent years. METHODOLOGICAL/PRINCIPAL FINDINGS: Here, we describe new fossils attributable to Djebelemur martinezi, a≈50 Ma primate from Tunisia (Djebel Chambi. This taxon was originally interpreted as a cercamoniine adapiform based on limited information from its lower dentition. The new fossils provide anatomical evidence demonstrating that Djebelemur was not an adapiform but clearly a distant relative of lemurs, lorises and galagos. Cranial, dental and postcranial remains indicate that this diminutive primate was likely nocturnal, predatory (primarily insectivorous, and engaged in a form of generalized arboreal quadrupedalism with frequent horizontal leaping. Djebelemur did not have an anterior lower dentition as specialized as that characterizing most crown strepsirhines (i.e., tooth-comb, but it clearly exhibited a transformed antemolar pattern representing an early stage of a crown strepsirhine-like adaptation ("pre-tooth-comb". CONCLUSIONS/SIGNIFICANCE: These new fossil data suggest that the differentiation of the tooth-comb must postdate the djebelemurid

  11. Effects of the Lexington LaserComb on hair regrowth in the C3H/HeJ mouse model of alopecia areata.

    Science.gov (United States)

    Wikramanayake, Tongyu Cao; Rodriguez, Rosa; Choudhary, Sonal; Mauro, Lucia M; Nouri, Keyvan; Schachner, Lawrence A; Jimenez, Joaquin J

    2012-03-01

    Alopecia areata (AA) is a common autoimmune disease that presents with non-scarring alopecia. It is characterized by intra- or peri-follicular lymphocytic infiltrates composed of CD4+ and CD8+ T-cells on histology. To this day, few treatments are effective for AA. Here we present findings of using a low-level laser comb to alleviate the symptoms of AA in a C3H/HeJ mouse model for AA. Fourteen C3H/HeJ mice with induced AA were used in this study. Two were killed to confirm AA through histology. The remaining 12 mice were randomized into two groups; group I received HairMax LaserComb (wavelength: 655 nm, beam diameter lasers) for 20 s daily, three times per week for a total of 6 weeks; group II was treated similarly, except that the laser was turned off (sham-treated). After 6 weeks of LaserComb treatment, hair regrowth was observed in all the mice in group I (laser-treated) but none in group II (sham-treated). On histology, increased number of anagen hair follicles was observed in laser-treated mice. On the other hand, sham-treated mice demonstrated hair follicles in the telogen phase with no hair shaft. LaserComb seems to be an effective and convenient device for the treatment of AA in the C3H/HeJ mouse model. Human studies are required to determine the efficacy and safety of this device for AA therapy.

  12. Description and experimental transmission of Tetracapsuloides vermiformis n. sp (Cnidaria: Myxozoa) and guidelines for describing malacosporean species including reinstatement of Buddenbrockia bryozoides n. comb. (syn. Tetracapsula bryozoides)

    Czech Academy of Sciences Publication Activity Database

    Patra, Sneha; Hartigan, Ashlie; Morris, D.J.; Kodádková, Alena; Holzer, Astrid S.

    2017-01-01

    Roč. 144, č. 4 (2017), s. 497-511 ISSN 0031-1820 R&D Projects: GA ČR(CZ) GBP505/12/G112 Institutional support: RVO:60077344 Keywords : Buddenbrockia bryozoides n. comb. * Buddenbrockia plumatellae * Malacosporea * morphological variation * Myxozoa * species discrimination * taxonomy * Tetracapsuloides vermiformis n. sp. Subject RIV: EG - Zoology OBOR OECD: Zoology Impact factor: 2.713, year: 2016

  13. Beyond the 'safe sex' propaganda.

    Science.gov (United States)

    Hadzic, Maja; Khajehei, Marjan

    2010-01-01

    In this paper, we discuss sexual relationships among teenagers, the related issues, and suggest addressing the issues through effective education programs for both teenagers and their parents. We also discuss the main issues resulting from initiation of sexual relationship during adolescence such as unwanted pregnancy, maternal mortality, abortion, sexually transmitted diseases and damaged mental health. In addition, we highlight the lack of adequate sex education in teenagers and emphasize on the negative influence of TV programs and the harmful effects of dysfunctional families. Moreover, this article proposes equipping teenagers with knowledge that will help them understand not only physical but also emotional, social, and mental dynamics of sexual relationships. We believe that this approach would intervene much earlier in their life, help teenagers make healthy decision and minimize negative consequences of their personal choices.

  14. [Food additives and healthiness].

    Science.gov (United States)

    Heinonen, Marina

    2014-01-01

    Additives are used for improving food structure or preventing its spoilage, for example. Many substances used as additives are also naturally present in food. The safety of additives is evaluated according to commonly agreed principles. If high concentrations of an additive cause adverse health effects for humans, a limit of acceptable daily intake (ADI) is set for it. An additive is a risk only when ADI is exceeded. The healthiness of food is measured on the basis of nutrient density and scientifically proven effects.

  15. Photodynamic efficacy of liposome-delivered hypocrellin B in microvascular endothelial cells in vitro and chicken combs in vivo: a potential photosensitizer for port wine stain

    International Nuclear Information System (INIS)

    Chen, H X; Zou, X B; Yang, Z F; Zhu, J G; Gu, Y; Deng, H; Zhao, J Q

    2013-01-01

    Photodynamic therapy (PDT) has been proved a successful method for port wine stain (PWS), but the prolonged skin photosensitivity induced by the photosensitizers used currently seriously limits the clinical application of PDT. In this study, we investigate the feasibility of hypocrellin B (HB), a promising second-generation photosensitizer for the treatment of PWS. The photodynamic effect of liposome-delivered HB was evaluated in vitro with microvascular endothelial cells (MEC) and in vivo with chicken combs. The dark cytotoxicity and photocytotoxicity of liposomal HB in MEC were evaluated using the MTT assay. Gross and histological examinations were performed to investigate the selective occlusion of the superficial dermal microvasculature in the chicken comb. The result showed that photocytotoxicity of liposomal HB was dependent on both light dose and drug concentration. PDT with HB (0.5–1 mg kg −1 ) and a light dose of 120 J cm −2 showed selective destruction of the superficial dermal microvasculature of the chicken comb, leaving the overlying epidermis intact. This is the first study to investigate the potential efficacy of HB-PDT as a novel modality for the treatment of PWS. These findings suggest that liposomal HB is a safe and effective photosensitizer for PWS. (paper)

  16. Sex Education with Young Children.

    Science.gov (United States)

    Koblinsky, Sally; And Others

    1980-01-01

    Discusses guidelines (developed by the Oregon State University Early Childhood Sex Education Project) for developing teacher-parent cooperation in providing sex education to young children. The guidelines concern how to talk about body differences and body functions; how to deal with masturbation, sex play and obscene language; and how to involve…

  17. YY Sex: a Polar Candidate

    Science.gov (United States)

    Gabdeev, M. M.; Shimanskiy, V. V.; Borisov, N. V.; Tazieva, Z. R.

    2017-06-01

    We present spectroscopic investigations of a cataclysmic variable star, YY Sex. There are some uncertainties in the classification of this object. We calculate Doppler maps for Hβ and HeII λ4686Å and show that there is no sign of disk accretion in YY Sex. Consequently, we conclude that YY Sex is a polar.

  18. Sex Education: Challenges and Choices

    Science.gov (United States)

    MacKenzie, Alison; Hedge, Nicki; Enslin, Penny

    2017-01-01

    Noting public concern about sexual exploitation, abuse and sexualisation, we argue that sex education in the UK needs revision. Choice is a feature of current sex education policy and, acknowledging that choice can be problematic, we defend its place in an approach to sex education premised on informed deliberation, relational autonomy, a…

  19. Sex Stereotyping Hurts All Kids.

    Science.gov (United States)

    Cutright, Melitta J.

    1991-01-01

    Sex stereotyping (raising boys and girls to be different because of their sex) begins at birth. The article reviews studies detailing sex stereotyping practices and offers suggestions on what parents can do to avoid them. A list of suggestions for raising children in a nonsexist way is included. (SM)

  20. Sex Steroid Actions in Male Bone

    Science.gov (United States)

    Laurent, Michaël R.; Claessens, Frank; Gielen, Evelien; Lagerquist, Marie K.; Vandenput, Liesbeth; Börjesson, Anna E.; Ohlsson, Claes

    2014-01-01

    Sex steroids are chief regulators of gender differences in the skeleton, and male gender is one of the strongest protective factors against osteoporotic fractures. This advantage in bone strength relies mainly on greater cortical bone expansion during pubertal peak bone mass acquisition and superior skeletal maintenance during aging. During both these phases, estrogens acting via estrogen receptor-α in osteoblast lineage cells are crucial for male cortical and trabecular bone, as evident from conditional genetic mouse models, epidemiological studies, rare genetic conditions, genome-wide meta-analyses, and recent interventional trials. Genetic mouse models have also demonstrated a direct role for androgens independent of aromatization on trabecular bone via the androgen receptor in osteoblasts and osteocytes, although the target cell for their key effects on periosteal bone formation remains elusive. Low serum estradiol predicts incident fractures, but the highest risk occurs in men with additionally low T and high SHBG. Still, the possible clinical utility of serum sex steroids for fracture prediction is unknown. It is likely that sex steroid actions on male bone metabolism rely also on extraskeletal mechanisms and cross talk with other signaling pathways. We propose that estrogens influence fracture risk in aging men via direct effects on bone, whereas androgens exert an additional antifracture effect mainly via extraskeletal parameters such as muscle mass and propensity to fall. Given the demographic trends of increased longevity and consequent rise of osteoporosis, an increased understanding of how sex steroids influence male bone health remains a high research priority. PMID:25202834