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1

Loss-of-function Additional sex combs like 1 mutations disrupt hematopoiesis but do not cause severe myelodysplasia or leukemia  

PubMed Central

The Additional sex combs like 1 (Asxl1) gene is 1 of 3 mammalian homologs of the Additional sex combs (Asx) gene of Drosophila. Asx is unusual because it is required to maintain both activation and silencing of Hox genes in flies and mice. Asxl proteins are characterized by an amino terminal homology domain, by interaction domains for nuclear receptors, and by a C-terminal plant homeodomain protein-protein interaction domain. A recent study of patients with myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) revealed a high incidence of truncation mutations that would delete the PHD domain of ASXL1. Here, we show that Asxl1 is expressed in all hematopoietic cell fractions analyzed. Asxl1 knockout mice exhibit defects in frequency of differentiation of lymphoid and myeloid progenitors, but not in multipotent progenitors. We do not detect effects on hematopoietic stem cells, or in peripheral blood. Notably, we do not detect severe myelodysplastic phenotypes or leukemia in this loss-of-function model. We conclude that Asxl1 is needed for normal hematopoiesis. The mild phenotypes observed may be because other Asxl genes have redundant function with Asxl1, or alternatively, MDS or oncogenic phenotypes may result from gain-of-function Asxl mutations caused by genomic amplification, gene fusion, or truncation of Asxl1. PMID:19861679

Fisher, Cynthia L.; Pineault, Nicolas; Brookes, Christy; Helgason, Cheryl D.; Ohta, Hideaki; Bodner, Caroline; Hess, Jay L.; Humphries, R. Keith

2010-01-01

2

Loss-of-function Additional sex combs like 1 mutations disrupt hematopoiesis but do not cause severe myelodysplasia or leukemia.  

PubMed

The Additional sex combs like 1 (Asxl1) gene is 1 of 3 mammalian homologs of the Additional sex combs (Asx) gene of Drosophila. Asx is unusual because it is required to maintain both activation and silencing of Hox genes in flies and mice. Asxl proteins are characterized by an amino terminal homology domain, by interaction domains for nuclear receptors, and by a C-terminal plant homeodomain protein-protein interaction domain. A recent study of patients with myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) revealed a high incidence of truncation mutations that would delete the PHD domain of ASXL1. Here, we show that Asxl1 is expressed in all hematopoietic cell fractions analyzed. Asxl1 knockout mice exhibit defects in frequency of differentiation of lymphoid and myeloid progenitors, but not in multipotent progenitors. We do not detect effects on hematopoietic stem cells, or in peripheral blood. Notably, we do not detect severe myelodysplastic phenotypes or leukemia in this loss-of-function model. We conclude that Asxl1 is needed for normal hematopoiesis. The mild phenotypes observed may be because other Asxl genes have redundant function with Asxl1, or alternatively, MDS or oncogenic phenotypes may result from gain-of-function Asxl mutations caused by genomic amplification, gene fusion, or truncation of Asxl1. PMID:19861679

Fisher, Cynthia L; Pineault, Nicolas; Brookes, Christy; Helgason, Cheryl D; Ohta, Hideaki; Bodner, Caroline; Hess, Jay L; Humphries, R Keith; Brock, Hugh W

2010-01-01

3

Drosophila Sex Combs as a Model of Evolutionary Innovations  

PubMed Central

The diversity of animal and plant forms is shaped by nested evolutionary innovations. Understanding the genetic and molecular changes responsible for these innovations is therefore one of the key goals of evolutionary biology. From the genetic point of view, the origin of novel traits implies the origin of new regulatory pathways to control their development. To understand how these new pathways are assembled in the course of evolution, we need model systems that combine relatively recent innovations with a powerful set of genetic and molecular tools. One such model is provided by the Drosophila sex comb – a male-specific morphological structure that evolved in a relatively small lineage related to the model species D. melanogaster. Our extensive knowledge of sex comb development in D. melanogaster provides the basis for investigating the genetic changes responsible for sex comb origin and diversification. At the same time, sex combs can change on microevolutionary timescales and differ spectacularly among closely related species, providing opportunities for direct genetic analysis and for integrating developmental and population-genetic approaches. Sex comb evolution is associated with the origin of novel interactions between HOX and sex determination genes. Activity of the sex determination pathway was brought under the control of the HOX code to become segment-specific, while HOX gene expression became sexually dimorphic. At the same time, both HOX and sex determination genes were integrated into the intrasegmental spatial patterning network, and acquired new joint downstream targets. Phylogenetic analysis shows that similar sex comb morphologies evolved independently in different lineages. Convergent evolution at the phenotypic level reflects convergent changes in the expression of HOX and sex determination genes, involving both independent gains and losses of regulatory interactions. However, the downstream cell differentiation programs have diverged between species, and in some lineages similar adult morphologies are produced by different morphogenetic mechanisms. These features make the sex comb an excellent model for examining not only the genetic changes responsible for its evolution, but also the cellular processes that translate DNA sequence changes into morphological diversity. The origin and diversification of sex combs provides insights into the roles of modularity, cooption, and regulatory changes in evolutionary innovations, and can serve as a model for understanding the origin of the more drastic novelties that define higher-order taxa. PMID:23016935

Kopp, Artyom

2011-01-01

4

Evolution of Drosophila sex comb length illustrates the inextricable interplay between selection and variation  

PubMed Central

In spite of the diversity of possible biological forms observed in nature, a limited range of morphospace is frequently occupied for a given trait. Several mechanisms have been proposed to explain this bias in the distribution of phenotypes including selection, drift, and developmental constraints. Despite extensive work on phenotypic bias, the underlying developmental mechanisms explaining why particular regions of morphological space remain unoccupied are poorly understood. To address this issue, we studied the sex comb, a group of modified bristles used in courtship that shows marked morphological diversity among Drosophila species. In many Drosophila species including Drosophila melanogaster, the sex comb rotates 90° to a vertical position during development. Here we analyze the effect of changing D. melanogaster sex comb length on the process of rotation. We find that artificial selection changes the number of bristles per comb without a proportional change in the space available for rotation. As a result, when increasing sex comb length, rather than displaying a similar straight vertical shape observed in other Drosophila species, long sex combs bend because rotation is blocked by a neighboring row of bristles. Our results show ways in which morphologies that would be favored by natural selection are apparently impossible to achieve developmentally. These findings highlight the potential role of development in modifying selectable variation in the evolution of Drosophila sex comb length. PMID:25197080

Malagón, Juan N.; Ahuja, Abha; Sivapatham, Gabilan; Hung, Julian; Lee, Jiwon; Muñoz-Gómez, Sergio A.; Atallah, Joel; Singh, Rama S.; Larsen, Ellen

2014-01-01

5

Sex Combs are Important for Male Mating Success in Drosophila melanogaster  

Microsoft Academic Search

The sex comb is one of the most rapidly evolving male-specific traits in Drosophila, making it an attractive model to study sexual selection and developmental evolution. Drosophila males use their sex combs to grasp the females’ abdomen and genitalia and to spread their wings prior to copulation. To test\\u000a the role of this structure in male mating success in Drosophila

Chen Siang Ng; Artyom Kopp

2008-01-01

6

Genetic Basis of a Violation of Dollo’s Law: Re-Evolution of Rotating Sex Combs in Drosophila bipectinata  

PubMed Central

Phylogenetic analyses suggest that violations of “Dollo’s law”—that is, re-evolution of lost complex structures—do occur, albeit infrequently. However, the genetic basis of such reversals has not been examined. Here, we address this question using the Drosophila sex comb, a recently evolved, male-specific morphological structure composed of modified bristles. In some species, sex comb development involves only the modification of individual bristles, while other species have more complex “rotated” sex combs that are shaped by coordinated migration of epithelial tissues. Rotated sex combs were lost in the ananassae species subgroup and subsequently re-evolved, ?12 million years later, in Drosophila bipectinata and its sibling species. We examine the genetic basis of the differences in sex comb morphology between D. bipectinata and D. malerkotliana, a closely related species with a much simpler sex comb representing the ancestral condition. QTL mapping reveals that >50% of this difference is controlled by one chromosomal inversion that covers ?5% of the genome. Several other, larger inversions do not contribute appreciably to the phenotype. This genetic architecture suggests that rotating sex combs may have re-evolved through changes in relatively few genes. We discuss potential developmental mechanisms that may allow lost complex structures to be regained. PMID:23086218

Seher, Thaddeus D.; Ng, Chen Siang; Signor, Sarah A.; Podlaha, Ondrej; Barmina, Olga; Kopp, Artyom

2012-01-01

7

Evolution of sex comb from the primitive bristle pattern in Drosophila is associated with modification in the developmental regulatory protein Dachshund.  

PubMed

Sex comb is a recently evolved male specific character confined to the Sophophoran group of Drosophila. Such innovations in phenotypes as Waddington proposed, are, outcome of "canalization" in developmental pathways that occur due to mutations creating "choice points" in genetic regulatory pathways. Our interest in the present study is to understand the shifts in genetic network, which has lead to the origin of sex comb from the basic bristle pattern that is seen in rest of the members of Drosophilidae. Here we have made a comparative analysis of expression of some of the key regulators of sex comb morphogenesis, between D. melanogaster and a group of selected species, which primitively lack sex comb. Sex combs reduced (Scr), dachshund (dac), and bric-a-brac (bab) gene expression were studied. We show that, primitive bristle pattern is marked by a strikingly down regulated expression of Sex combs reduced in the first tarsal segment of the prothoracic leg discs of male flies. Further a remarkable change with respect to Dachshund, an activator of sex combs reduced gene in the sex comb regulatory pathway, is seen. This is attributed to changes in DAC protein that might have taken place between the two groups of species. bric-a-brac does not reveal any significant expression modulation between the sex comb bearing and the primitive patterned species. Earlier works had shown that within the Sophophoran group, dynamic changes in SCR expression is responsible for the diversity seen in sex comb morphology, where as no such variation is witnessed with respect to DAC expression. Our findings have demonstrated that the scenario is different between the group primitively lacking sex comb and D. melanogaster wherein an obvious change in the protein has taken place. genesis 51:97-109, 2013, 2013. © 2012 Wiley Periodicals, Inc. PMID:23197370

Devi, Thangjam Ranjita; Amruthavalli, C; Shyamala, B V

2013-02-01

8

Identification of polycomb and trithorax group responsive elements in the regulatory region of the Drosophila homeotic gene Sex combs reduced  

Microsoft Academic Search

The Drosophilia homeotic gene Sex combs reduced (Scr) is necessary for the establishment and maintenance of the morphological identity of the labial and prothoracic segments. In the early embryo, its expression pattern is established through the activity of several gap and segmentation gene products, as well as other transcription factors. Once established, the Polycomb group (Pc-G) and trithorax group (trx-G)

J. G. Jr. Gindhart; T. C. Kaufman

1995-01-01

9

Characterization of the Cis-Regulatory Region of the Drosophila Homeotic Gene Sex Combs Reduced  

PubMed Central

The Drosophila homeotic gene Sex combs reduced (Scr) controls the segmental identity of the labial and prothoracic segments in the embryo and adult. It encodes a sequence-specific transcription factor that controls, in concert with other gene products, differentiative pathways of tissues in which Scr is expressed. During embryogenesis, Scr accumulation is observed in a discrete spatiotemporal pattern that includes the labial and prothoracic ectoderm, the subesophageal ganglion of the ventral nerve cord and the visceral mesoderm of the anterior and posterior midgut. Previous analyses have demonstrated that breakpoint mutations located in a 75-kb interval, including the Scr transcription unit and 50 kb of upstream DNA, cause Scr misexpression during development, presumably because these mutations remove Scr cis-regulatory sequences from the proximity of the Scr promoter. To gain a better understanding of the regulatory interactions necessary for the control of Scr transcription during embryogenesis, we have begun a molecular analysis of the Scr regulatory interval. DNA fragments from this 75-kb region were subcloned into P-element vectors containing either an Scr-lacZ or hsp70-lacZ fusion gene, and patterns of reporter gene expression were assayed in transgenic embryos. Several fragments appear to contain Scr regulatory sequences, as they direct reporter gene expression in patterns similar to those normally observed for Scr, whereas other DNA fragments direct Scr reporter gene expression in developmentally interesting but non-Scr-like patterns during embryogenesis. Scr expression in some tissues appears to be controlled by multiple regulatory elements that are separated, in some cases, by more than 20 kb of intervening DNA. Interestingly, regulatory sequences that direct reporter gene expression in an Scr-like pattern in the anterior and posterior midgut are imbedded in the regulatory region of the segmentation gene fushi tarazu (ftz), which is normally located between 10 and 20 kb 5' of the Scr transcription start site. This analysis provides an entry point for the study of how Scr transcription is regulated at the molecular level. PMID:7713432

Gindhart-Jr., J. G.; King, A. N.; Kaufman, T. C.

1995-01-01

10

A Logical OR Redundancy Within the Asx-Pro-Asx-Gly Type I beta-Turn Motif  

SciTech Connect

Turn secondary structure is essential to the formation of globular protein architecture. Turn structures are, however, much more complex than either ?-helix or ?-sheet, and the thermodynamics and folding kinetics are poorly understood. Type I ?-turns are the most common type of reverse turn, and they exhibit a statistical consensus sequence of Asx-Pro-Asx-Gly (where Asx is Asp or Asn). A comprehensive series of individual and combined Asx mutations has been constructed within three separate type I 3:5 G1 bulge ?-turns in human fibroblast growth factor-1, and their effects on structure, stability, and folding have been determined. The results show a fundamental logical OR relationship between the Asx residues in the motif, involving H-bond interactions with main-chain amides within the turn. These interactions can be modulated by additional interactions with residues adjacent to the turn at positions i + 4 and i + 6. The results show that the Asx residues in the turn motif make a substantial contribution to the overall stability of the protein, and the Asx logical OR relationship defines a redundant system that can compensate for deleterious point mutations. The results also show that the stability of the turn is unlikely to be the prime determinant of formation of turn structure in the folding transition state.

Lee,J.; Dubey, V.; Longo, L.; Blaber, M.

2008-01-01

11

A Logical OR Redundancy within the Asx-Pro-Asx-Gly Type 1 {Beta}-Turn Motif  

SciTech Connect

Turn secondary structure is essential to the formation of globular protein architecture. Turn structures are, however, much more complex than either {alpha}-helix or {beta}-sheet, and the thermodynamics and folding kinetics are poorly understood. Type I {beta}-turns are the most common type of reverse turn, and they exhibit a statistical consensus sequence of Asx-Pro-Asx-Gly (where Asx is Asp or Asn). A comprehensive series of individual and combined Asx mutations has been constructed within three separate type I 3:5 G1 bulge {beta}-turns in human fibroblast growth factor-1, and their effects on structure, stability, and folding have been determined. The results show a fundamental logical OR relationship between the Asx residues in the motif, involving H-bond interactions with main-chain amides within the turn. These interactions can be modulated by additional interactions with residues adjacent to the turn at positions i + 4 and i + 6. The results show that the Asx residues in the turn motif make a substantial contribution to the overall stability of the protein, and the Asx logical OR relationship defines a redundant system that can compensate for deleterious point mutations. The results also show that the stability of the turn is unlikely to be the prime determinant of formation of turn structure in the folding transition state.

Lee, Jihun; Dubey, Vikash Kumar; Longo, Lian M.; Blaber, Michael (FSU)

2008-04-19

12

Identification of Polycomb and Trithorax Group Responsive Elements in the Regulatory Region of the Drosophila Homeotic Gene Sex Combs Reduced  

PubMed Central

The Drosophila homeotic gene Sex combs reduced (Scr) is necessary for the establishment and maintenance of the morphological identity of the labial and prothoracic segments. In the early embryo, its expression pattern is established through the activity of several gap and segmentation gene products, as well as other transcription factors. Once established, the Polycomb group (Pc-G) and trithorax group (trx-G) gene products maintain the spatial pattern of Scr expression for the remainder of development. We report the identification of DNA fragments in the Scr regulatory region that may be important for its regulation by Polycomb and trithorax group gene products. When DNA fragments containing these regulatory sequences are subcloned into P-element vectors containing a white minigene, transformants containing these constructs exhibit mosaic patterns of pigmentation in the adult eye, indicating that white minigene expression is repressed in a clonally heritable manner. The size of pigmented and nonpigmented clones in the adult eye suggests that the event determining whether a cell in the eye anlagen will express white occurs at least as early as the first larval instar. The amount of white minigene repression is reduced in some Polycomb group mutants, whereas repression is enhanced in flies mutant for a subset of trithorax group loci. The repressor activity of one fragment, normally located in Scr Intron 2, is increased when it is able to homologously pair, a property consistent with genetic data suggesting that Scr exhibits transvection. Another Scr regulatory fragment, normally located 40 kb upstream of the Scr promoter, silences ectopic expression of an Scr-lacZ fusion gene in the embryo and does so in a Polycomb-dependent manner. We propose that the regulatory sequences located within these DNA fragments may normally mediate the regulation of Scr by proteins encoded by members of the Polycomb and trithorax group loci. PMID:7713433

Gindhart-Jr., J. G.; Kaufman, T. C.

1995-01-01

13

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

PubMed

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. PMID:25772304

Guo, Jiwei; Jin, Dan

2015-05-01

14

Intermediate phase, network demixing, boson and floppy modes, and compositional trends in glass transition temperatures of binary AsxS1-x system  

E-print Network

by the proportionately larger free volumes of sulfides than selenides and the absence of chemical bond-strength scalingIntermediate phase, network demixing, boson and floppy modes, and compositional trends in glass manuscript received 13 November 2008; published 30 December 2008 The structure of binary AsxS1-x glasses

Boolchand, Punit

15

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

PubMed Central

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

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

2010-01-01

16

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

PubMed

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

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

2010-06-01

17

Drosophila O-GlcNAc transferase (OGT) is encoded by the Polycomb group (PcG) gene, super sex combs (sxc).  

PubMed

O-linked N-acetylglucosamine transferase (OGT) reversibly modifies serine and threonine residues of many intracellular proteins with a single beta-O-linked N-acetylglucosamine residue (O-GlcNAc), and has been implicated in insulin signaling, neurodegenerative disease, cellular stress response, and other important processes in mammals. OGT also glycosylates RNA polymerase II and various transcription factors, which suggests that it might be directly involved in transcriptional regulation. We report here that the Drosophila OGT is encoded by the Polycomb group (PcG) gene, super sex combs (sxc). Furthermore, major sites of O-GlcNAc modification on polytene chromosomes correspond to PcG protein binding sites. Our results thus suggest a direct role for O-linked glycosylation by OGT in PcG-mediated epigenetic gene silencing, which is important in developmental regulation, stem cell maintenance, genomic imprinting, and cancer. In addition, we observe rescue of sxc lethality by a human Ogt cDNA transgene; thus Drosophila may provide an ideal model to study important functional roles of OGT in mammals. PMID:19666537

Sinclair, Donald A R; Syrzycka, Monika; Macauley, Matthew S; Rastgardani, Tara; Komljenovic, Ivana; Vocadlo, David J; Brock, Hugh W; Honda, Barry M

2009-08-11

18

Doping of GaN12xAsx with high As content A. X. Levander,1,2  

E-print Network

Doping of GaN12xAsx with high As content A. X. Levander,1,2 S. V. Novikov,3 Z. Liliental-Weber,1 R; published online 2 November 2011) Recent work has shown that GaN1Ã?xAsx can be grown across the entire report the bipolar doping of GaN1Ã?xAsx with high As content to conductivities above 4 S=cm at room

Wu, Junqiao

19

Cantor's Comb  

NSDL National Science Digital Library

In this activity, students enter in a fraction to be removed from the center of line segments creating what is called Cantor’s Comb. This activity allows students to explore sequences and the idea of limit. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

2010-01-01

20

Decentralized control of drone comb construction in honey bee colonies  

Microsoft Academic Search

Honey bee colonies furnish their nests with two types of comb distinguished by cell size: large cells for rearing males (drone\\u000a comb) and small cells for rearing workers (worker comb). The bees actively regulate the relative quantity of each type, a\\u000a behavior likely to be important in setting a colony's sex ratio. Experimental analysis of the information pathways and control

Stephen C. Pratt

1998-01-01

21

Frequency comb swept lasers  

E-print Network

We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep ...

Tsai, Tsung-Han

22

Novel strained InP\\/InAsxP1 - x quantum-well modulation-doped heterostructures  

Microsoft Academic Search

We report the first investigation of transport properties of two-dimensional electron systems in strained InAsxP1?x quantum-well channels. The InP\\/InAsxP1?x modulation-doped heterostructures were grown by the low-pressure OMCVD technique. The dependence of the transport parameters on the arsenic composition (x) has been studied using Hall, Shubnikov de Haas, and cyclotron resonance measurements. Hall mobilities of 6100 and 52 700 cm2\\/V s,

W.-P. Hong; R. Bhat; J. Hayes; F. Derosa; M. Leadbeater; M. Koza

1992-01-01

23

Low gap amorphous GaN1-xAsx alloys grown on glass substrate K. M. Yu,1,a  

E-print Network

Low gap amorphous GaN1-xAsx alloys grown on glass substrate K. M. Yu,1,a S. V. Novikov,2 R September 2010 Amorphous GaN1-xAsx layers with As content in the range of x=0.1 to 0.6 were grown defined optical absorption edges. The measured band gap values for the crystalline and amorphous GaN1-x

Wu, Junqiao

24

Compact electrostatic comb actuator  

DOEpatents

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).

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

2000-01-01

25

Smooth Combs Inside Hedgehogs  

E-print Network

We use techniques of tube-log Riemann surfaces due to R.Perez-Marco to construct a hedgehog containing smooth $C^{\\infty}$ combs. The hedgehog is a common hedgehog for a family of commuting non-linearisable holomorphic maps with a common indifferent fixed point. The comb is made up of smooth curves, and is transversally bi-H\\"older regular.

Biswas, Kingshook

2009-01-01

26

Frequency comb swept lasers  

PubMed Central

We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep rate of 1kHz and 120kHz, respectively over a 135nm tuning range centered at 1310nm with average output powers of 50mW. A 25GHz free spectral range frequency comb filter in the swept lasers causes the lasers to generate a series of well defined frequency steps. The narrow bandwidth (0.015nm) of the frequency comb filter enables a ~?1.2dB sensitivity roll off over ~3mm range, compared to conventional swept source and FDML lasers which have ?10dB and ?5dB roll offs, respectively. Measurements at very long ranges are possible with minimal sensitivity loss, however reflections from outside the principal measurement range of 0–3mm appear aliased back into the principal range. In addition, the frequency comb output from the lasers are equally spaced in frequency (linear in k-space). The filtered laser output can be used to self-clock the OCT interference signal sampling, enabling direct fast Fourier transformation of the fringe signals, without the need for fringe recalibration procedures. The design and operation principles of FC swept lasers are discussed and designs for short cavity lasers for OCT and interferometric measurement applications are proposed. PMID:19997365

Tsai, Tsung-Han; Zhou, Chao; Adler, Desmond C.; Fujimoto, James G.

2010-01-01

27

Electrophysics of micromechanical comb actuators  

Microsoft Academic Search

A simple approximate theory is developed for the electrostatic forces operating in a micromechanical comb actuator. The comb drive is considered both without (for simplicity) and with an underlying ground plane. The forces are partitioned into local forces (electric fields confined to the cross-sections of the individual comb fingers) and global force corrections (electric fields resulting from effective equipotential sheets

William A. Johnson; Larry K. Warne

1995-01-01

28

Butelase 1 is an Asx-specific ligase enabling peptide macrocyclization and synthesis.  

PubMed

Proteases are ubiquitous in nature, whereas naturally occurring peptide ligases, enzymes catalyzing the reverse reactions of proteases, are rare occurrences. Here we describe the discovery of butelase 1, to our knowledge the first asparagine/aspartate (Asx) peptide ligase to be reported. This highly efficient enzyme was isolated from Clitoria ternatea, a cyclic peptide-producing medicinal plant. Butelase 1 shares 71% sequence identity and the same catalytic triad with legumain proteases but does not hydrolyze the protease substrate of legumain. Instead, butelase 1 cyclizes various peptides of plant and animal origin with yields greater than 95%. With Kcat values of up to 17 s(-1) and catalytic efficiencies as high as 542,000 M(-1) s(-1), butelase 1 is the fastest peptide ligase known. Notably, butelase 1 also displays broad specificity for the N-terminal amino acids of the peptide substrate, thus providing a new tool for C terminus-specific intermolecular peptide ligations. PMID:25038786

Nguyen, Giang K T; Wang, Shujing; Qiu, Yibo; Hemu, Xinya; Lian, Yilong; Tam, James P

2014-09-01

29

STATIC ELECTRICITY Plastic combs  

E-print Network

STATIC ELECTRICITY Materials · Plastic combs · Balloons · Thread · Scissors · Cheerios · Paper plates · Plastic lids · Unflavored gelatin powder · Long hair, fleece jacket, wool sweater..... Questions of Cheerios on a paper plate. 2. Take the plastic lid and rub it against whatever is available (hair, fleece

Benitez-Nelson, Claudia

30

Squeezing frequency combs  

E-print Network

We have developed the full theory of a synchronously pumped type I optical parametric oscillator (SPOPO). We derive expressions for the oscillation threshold and the characteristics of the generated mode-locked signal beam. We calculate the output quantum fluctuations of the device, and find that, in the degenerate case (coincident signal and idler set of frequencies), perfect squeezing is obtained when one approaches threshold from below for a well defined "super-mode', or frequency comb, consisting of a coherent linear superposition of signal modes of different frequencies which are resonant in the cavity.

German J. De Valcarcel; Giuseppe Patera; Nicolas Treps; Claude Fabre

2006-05-15

31

Self-consistent determination of the band offsets in InAsxP1-x\\/InP strained-layer quantum wells and the bowing parameter of bulk InAsxP1-x  

Microsoft Academic Search

Low- and room-temperature optical absorption spectra are presented for a series of InAsxP1-x\\/InP strainedlayer multiple quantum well structures (0.11<=x<=0.35) grown by low-pressure metal-organic vapor phase epitaxy using trimethylindium, tertiarybutylarsine, and phosphine as precursors. The well widths and compositions in these structures are exactly determined from the use of both high-resolution x-ray diffraction and transmission electron microscopy on the same samples.

M. Beaudoin; A. Bensaada; R. Leonelli; P. Desjardins; R. A. Masut; L. Isnard; A. Chennouf; G. L'Espérance

1996-01-01

32

Material properties and modeling characteristics for MnFeP1-xAsx materials for application in magnetic refrigeration  

NASA Astrophysics Data System (ADS)

Compounds of MnFeP1-xAsx have received attention recently for their use in active magnetic regenerators (AMR) because of their relatively high isothermal entropy change and adiabatic temperature change with magnetization. However, the materials also generally exhibit a significant magnetic and thermal hysteresis, and it is not well understood how the hysteresis will affect performance in a practical AMR device. The amount of hysteresis shown by a material can be controlled to an extent by tuning the processing conditions used during material synthesis; therefore, knowledge of the practical impact of hysteresis is a key element to guide successful material development and synthesis. The properties of a magnetocaloric MnFeP1-xAsx compound are characterized as a function of temperature and applied magnetic field, and the results are used to assess the effects of hysteresis on magnetocaloric properties. Different methods of building property functions from the measured specific heat, magnetization, and adiabatic temperature change are presented. It is shown that model predictions can be highly dependent on how the properties that are used by the AMR model are calculated.

Engelbrecht, K.; Nielsen, K. K.; Bahl, C. R. H.; Carroll, C. P.; van Asten, D.

2013-05-01

33

Fragile-strong behavior in the AsxSe1-x glass forming system in relation to structural dimensionality  

NASA Astrophysics Data System (ADS)

A series of physical properties have been measured throughout and above the glass transition for the whole AsxSe1-x system, including the activation for viscous flow E?, the activation energy for enthalpy relaxation EH, and the activation energy for structural relaxation Ea obtained by specific heat spectroscopy. All properties show a double minimum at an average coordination number = 2.3 and = 2.5 with a local maximum at = 2.4. This is in stark contrast to the physical properties previously measured on the same samples at room temperature and which instead show a single minimum centered at = 2.4. The observed trend is consistent with the dimensionality of the network derived from structural data obtained by nuclear magnetic resonance. An analysis of the complex heat capacity also reveals a bimodal relaxation process in As-rich glasses, which explains why they are kinetically fragile but appear thermodynamically strong. Finally, these results demonstrate that previous observations of an “intermediate phase” in AsxSe1-x glasses near = 2.3 is associated with the high temperature behavior of the glassy network and should be interpreted in terms of the temperature dependence of structural constraints rather than the number of constraints in the room-temperature glass.

Yang, Guang; Gulbiten, Ozgur; Gueguen, Yann; Bureau, Bruno; Sangleboeuf, Jean-Christophe; Roiland, Claire; King, Ellyn A.; Lucas, Pierre

2012-04-01

34

Mid-infrared frequency combs  

E-print Network

Laser frequency combs are coherent light sources that emit a broad spectrum consisting of discrete, evenly spaced narrow lines, each having an absolute frequency measurable within the accuracy of an atomic clock. Their development, a decade ago, in the near-infrared and visible domains has revolutionized frequency metrology with numerous windfalls into other fields such as astronomy or attosecond science. Extension of frequency comb techniques to the mid-infrared spectral region is now under exploration. Versatile mid-infrared frequency comb generators, based on novel laser gain media, nonlinear frequency conversion or microresonators, promise to significantly expand the tree of applications of frequency combs. In particular, novel approaches to molecular spectroscopy in the fingerprint region, with dramatically improved precision, sensitivity, recording time and/or spectral bandwidth may spark off new discoveries in the various fields relevant to molecular sciences.

Schliesser, Albert; Hänsch, Theodor W

2012-01-01

35

Cavity-Enhanced Direct Frequency Comb Spectroscopy  

E-print Network

Cavity-Enhanced Direct Frequency Comb Spectroscopy: Technology and Applications Florian Adler-molecule spectroscopy, ultrasensitive spectroscopy, frequency-domain ultrafast spectroscopy Abstract Cavity-enhanced direct frequency comb spectroscopy combines broad band- width, high spectral resolution, and ultrahigh

36

Scaling of Yb-Fiber Frequency Combs  

NASA Astrophysics Data System (ADS)

Immediately after their introduction in 1999, femtosecond laser frequency combs revolutionized the field of precision optical frequency metrology and are key elements in many experiments. Frequency combs based on femtosecond Er-fiber lasers based were demonstrated in 2005, allowing additionally rugged, compact set-ups and reliable unattended long-term operation. The introduction of Yb-fiber technology led to an dramatic improvement in fiber-comb performance in various aspects. Low-noise Yb-fiber femtosecond oscillators enabled a reduction of relative comb tooth linewidth to the sub-Hz level as well as scaling of the fundamental comb spacings up to 1 GHz. This is beneficial for any frequency-domain comb application due to the higher power per comb-mode. Many spectroscopic applications require, however, frequency combs way beyond the wavelength range accessible with broad band laser materials, so nonlinear conversion and hence higher peak intensity is required. We demonstrated power scaling of Yb-fiber frequency combs up to 80 W average power in a strictly linear chirped-pulse amplification schemes compatible with low-noise phase control. These high-power Yb-fiber-frequency combs facilitated not only the extension to the mid-IR spectral region. When coupled to a passive enhancement cavity, the average power can be further scaled to the kW-level opening new capabilities for XUV frequency combs via high-harmonic generation. All these advances of fiber-based frequency combs will trigger many novel applications both in fundamental and applied sciences. Schibli et al., Nature Photonics 2 355 (2008). Hartl et al., MF9 in Advanced Solid-State Photonics. 2009, Optical Society of America. Ruehl et al., AWC7 in Advanced Solid-State Photonics. 2010, Optical Society of America. Adler et al., Optics Letters 34 1330 (2009). Yost et al., Nature Physics 5 815 (2009).

Ruehl, Axel; Marcinkevicius, Andrius; Fermann, Martin E.; Hartl, Ingmar

2010-06-01

37

Atomic quantum memory for multimode frequency combs  

E-print Network

We propose a Raman quantum memory scheme that uses several atomic ensembles to store/retrieve the multimode highly entangled state of an optical quantum frequency comb, such as the one produced by parametric down-conversion of a pump frequency comb. We analyse the efficiency and the fidelity of such a quantum memory. Results show that our proposal may be helpful to multimode information processing using the different frequency bands of an optical frequency comb.

Z. Zheng; O. Mishina; N. Treps; C. Fabre

2015-01-27

38

Widely tunable extreme UV frequency comb generation.  

PubMed

Extreme UV (XUV) frequency comb generation in the wavelength range of 51 to 85 nm is reported based on high-order harmonic generation of two consecutive IR frequency comb pulses that were amplified in an optical parametric chirped pulse amplifier. The versatility of the system is demonstrated by recording direct XUV frequency comb excitation signals in He, Ne, and Ar with visibilities of up to 61%. PMID:21633437

Pinkert, T J; Kandula, D Z; Gohle, C; Barmes, I; Morgenweg, J; Eikema, K S E

2011-06-01

39

Atomic quantum memory for multimode frequency combs  

NASA Astrophysics Data System (ADS)

We propose a Raman quantum memory scheme that uses several atomic ensembles to store and retrieve the multimode highly entangled state of an optical quantum frequency comb, such as the one produced by parametric down-conversion of a pump frequency comb. We analyze the efficiency and the fidelity of such a quantum memory. Results show that our proposal may be helpful to multimode information processing using the different frequency bands of an optical frequency comb.

Zheng, Zhan; Mishina, Oxana; Treps, Nicolas; Fabre, Claude

2015-03-01

40

Visible wavelength astro-comb.  

PubMed

We demonstrate a tunable laser frequency comb operating near 420 nm with mode spacing of 20-50 GHz, usable bandwidth of 15 nm and output power per line of ~20 nW. Using the TRES spectrograph at the Fred Lawrence Whipple Observatory, we characterize this system to an accuracy below 1m/s, suitable for calibrating high-resolution astrophysical spectrographs used, e.g., in exoplanet studies. PMID:20940813

Benedick, Andrew J; Chang, Guoqing; Birge, Jonathan R; Chen, Li-Jin; Glenday, Alexander G; Li, Chih-Hao; Phillips, David F; Szentgyorgyi, Andrew; Korzennik, Sylvain; Furesz, Gabor; Walsworth, Ronald L; Kärtner, Franz X

2010-08-30

41

Phononic Frequency Combs through Nonlinear Resonances  

NASA Astrophysics Data System (ADS)

We explore an analogue of optical frequency combs in driven nonlinear phononic systems, and present a mechanism for generating phononic frequency combs through nonlinear resonances. In the underlying process, a set of phonon modes is simultaneously excited by the external driving which yields frequency combs with an array of discrete and equidistant spectral lines of each nonlinearly excited phonon mode. Frequency combs through nonlinear resonance of different orders are investigated, and in particular the possibility of correlation tailoring in higher-order cases is revealed. We suggest that our results can be applied in various nonlinear acoustic processes, such as phonon harvesting, and can also be generalized to other nonlinear systems.

Cao, L. S.; Qi, D. X.; Peng, R. W.; Wang, Mu; Schmelcher, P.

2014-02-01

42

Correlation between structure and physical properties of chalcogenide glasses in the AsxSe1-x system  

NASA Astrophysics Data System (ADS)

Physical properties of chalcogenide glasses in the AsxSe1-x system have been measured as a function of composition including the Young’s modulus E , shear modulus G , bulk modulus K , Poisson’s ratio ? , the density ? , and the glass transition Tg . All these properties exhibit a relatively sharp extremum at the average coordination number ?r?=2.4 . The structural origin of this trend is investigated by Raman spectroscopy and nuclear magnetic resonance. It is shown that the reticulation of the glass structure increases continuously until x=0.4 following the “chain crossing model” and then undergoes a transition toward a lower dimension pyramidal network containing an increasing number of molecular inclusions at x>0.4 . Simple theoretical estimates of the network bonding energy confirm a mismatch between the values of mechanical properties measured experimentally and the values predicted from a continuously reticulated structure, therefore corroborating the formation of a lower dimension network at high As content. The evolution of a wide range of physical properties is consistent with this sharp structural transition and suggests that there is no intermediate phase in these glasses at room temperature.

Yang, Guang; Bureau, Bruno; Rouxel, Tanguy; Gueguen, Yann; Gulbiten, Ozgur; Roiland, Claire; Soignard, Emmanuel; Yarger, Jeffery L.; Troles, Johann; Sangleboeuf, Jean-Christophe; Lucas, Pierre

2010-11-01

43

Arthur Wright Combs: A Humanistic Pioneer  

ERIC Educational Resources Information Center

Arthur Wright Combs (1912-1999) championed humanistic counseling and education. He proposed a theory that incorporated humanistic values and cognitive factors. This article features a review of his contributions, an overview of his theory, a synthesis of stories about Combs that were acquired during research interviews, and my commentary on his…

Magnuson, Sandy

2012-01-01

44

A frequency comb in the extreme ultraviolet  

Microsoft Academic Search

Since 1998, the interaction of precision spectroscopy and ultrafast laser science has led to several notable accomplishments. Femtosecond laser optical frequency `combs' (evenly spaced spectral lines) have revolutionized the measurement of optical frequencies and enabled optical atomic clocks. The same comb techniques have been used to control the waveform of ultrafast laser pulses, which permitted the generation of single attosecond

Christoph Gohle; Thomas Udem; Maximilian Herrmann; Jens Rauschenberger; Ronald Holzwarth; Hans A. Schuessler; Ferenc Krausz; Theodor W. Hänsch

2005-01-01

45

Microresonator-Based Optical Frequency Combs  

E-print Network

measure- ment (10), remote sensing, optical waveform (11) and microwave signal synthesis (12), and astro-locked lasers (1, 16). The frequency do- main spectrum of the output of a mode-locked laser constitutes an optical frequency comb. The comb arises from the periodic train of pulses emitted from such a laser (Fig

46

Long term comparison of two fiber based frequency comb systems  

Microsoft Academic Search

Mode-locked erbium-doped fiber lasers are ideal comb generators for optical frequency metrology. We compare two fiber frequency combs by measuring an optical frequency independently with both combs and comparing their results. The two frequency measurements agree within 6×10-16. This is to our knowledge the first direct comparison between two fiber based frequency combs.

Philipp Kubina; Peter Adel; Florian Adler; Gesine Grosche; Theodor W. Hänsch; Ronald Holzwarth; Alfred Leitenstorfer; Burghard Lipphardt; Harald Schnatz

2005-01-01

47

Frequency comb generation in superconducting resonators.  

PubMed

We have generated frequency combs spanning 0.5 to 20 GHz in superconducting ?/2 resonators at T=3??K. Thin films of niobium-titanium nitride enabled this development due to their low loss, high nonlinearity, low frequency dispersion, and high critical temperature. The combs nucleate as sidebands around multiples of the pump frequency. Selection rules for the allowed frequency emission are calculated using perturbation theory, and the measured spectrum is shown to agree with the theory. Sideband spacing is measured to be accurate to 1 part in 10(8). The sidebands coalesce into a continuous comb structure observed to cover at least several frequency octaves. PMID:25396390

Erickson, R P; Vissers, M R; Sandberg, M; Jefferts, S R; Pappas, D P

2014-10-31

48

Fractional diffusion on a fractal grid comb  

NASA Astrophysics Data System (ADS)

A grid comb model is a generalization of the well known comb model, and it consists of N backbones. For N =1 the system reduces to the comb model where subdiffusion takes place with the transport exponent 1 /2 . We present an exact analytical evaluation of the transport exponent of anomalous diffusion for finite and infinite number of backbones. We show that for an arbitrarily large but finite number of backbones the transport exponent does not change. Contrary to that, for an infinite number of backbones, the transport exponent depends on the fractal dimension of the backbone structure.

Sandev, Trifce; Iomin, Alexander; Kantz, Holger

2015-03-01

49

Frequency Comb Generation in Superconducting Resonators  

NASA Astrophysics Data System (ADS)

We have generated frequency combs spanning 0.5 to 20 GHz in superconducting ? /2 resonators at T =3 K . Thin films of niobium-titanium nitride enabled this development due to their low loss, high nonlinearity, low frequency dispersion, and high critical temperature. The combs nucleate as sidebands around multiples of the pump frequency. Selection rules for the allowed frequency emission are calculated using perturbation theory, and the measured spectrum is shown to agree with the theory. Sideband spacing is measured to be accurate to 1 part in 1 08. The sidebands coalesce into a continuous comb structure observed to cover at least several frequency octaves.

Erickson, R. P.; Vissers, M. R.; Sandberg, M.; Jefferts, S. R.; Pappas, D. P.

2014-10-01

50

Phase steps and resonator detuning measurements in microresonator frequency combs.  

PubMed

Experiments and theoretical modelling yielded significant progress toward understanding of Kerr-effect induced optical frequency comb generation in microresonators. However, the simultaneous Kerr-mediated interaction of hundreds or thousands of optical comb frequencies with the same number of resonator modes leads to complicated nonlinear dynamics that are far from fully understood. An important prerequisite for modelling the comb formation process is the knowledge of phase and amplitude of the comb modes as well as the detuning from their respective microresonator modes. Here, we present comprehensive measurements that fully characterize optical microcomb states. We introduce a way of measuring resonator dispersion and detuning of comb modes in a hot resonator while generating an optical frequency comb. The presented phase measurements show unpredicted comb states with discrete ? and ?/2 steps in the comb phases that are not observed in conventional optical frequency combs. PMID:25565467

Del'Haye, Pascal; Coillet, Aurélien; Loh, William; Beha, Katja; Papp, Scott B; Diddams, Scott A

2015-01-01

51

Vertically supported two-directional comb drive  

NASA Astrophysics Data System (ADS)

A vertically supported comb drive with the feasibility of actuation in two perpendicular directions utilizing electrostatic force from interdigitated comb-shape electrodes has been demonstrated. The prototype microstructures are made of 2 µm thick polysilicon by a standard surface micromachining process. They are vertically lifted after the final sacrificial layer releasing process and are fixed on the substrate with the assistance of micro locking springs and micro hinges. The microstructures can vibrate in the directions either parallel or normal to the comb fingers, depending on the physical setups of the supporting structures and the polarity of driving electrodes. Experimentally, under 10 V dc bias voltage and 10 V ac peak-to-peak driving voltage in air, the prototype structure is found to resonate at the first fundamental mode of 6.8 kHz in the parallel direction. In the direction normal to the surface of the comb fingers, several bands of vibration movements have been observed between 500 Hz and 11.9 kHz due to the strong coupling between the two comb structures. As such, these microresonators using the vertically supported two-directional comb drive might find potential applications in the area of MEMS or MOEMS including optical systems on a chip. A portion of this paper was presented at the 12th International Conference on Solid-State Sensors and Actuators (Transducers '03), 8-12 June 2003, Boston, USA.

Lee, Ki Bang; Lin, Liwei

2005-08-01

52

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

NASA Technical Reports Server (NTRS)

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.

Donaldson, C. H.

1977-01-01

53

Frequency comb swept lasers for optical coherence tomography  

E-print Network

We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep ...

Tsai, Tsung-Han

54

An NIR laser frequency comb for high precision Doppler  

E-print Network

An NIR laser frequency comb for high precision Doppler planet surveys Steve Osterman Center (CU) Jian Ge (UF) UF Steve Osterman NIR laser frequency comb BDEP 20 July 2009 + #12;Overview Why look/NIST/UF LFC Program Where can we go with this? Steve Osterman NIR laser frequency comb BDEP 20 July 2009 #12

Colorado at Boulder, University of

55

A new two-stage sharpened comb decimator  

Microsoft Academic Search

This paper presents a new sharpened comb decimator structure consisting of a cascade of a comb-filter based decimator and a sharpened comb decimator. The proposed realization scheme allows the sharpened section to operate at a lower rate that depends on the decimation factor of the first section. Using a polyphase decomposition, the subfilters of the first section can also be

Gordana Jovanovic-Dolecek; Sanjit K. Mitra

2005-01-01

56

Sharpening technique to decrease comb passband deviation  

NASA Astrophysics Data System (ADS)

The decimation filter is necessary to prevent aliasing during the process of decreasing sampling rate, which is called decimation. Due its simplicity, the most popular decimation filter is the comb filter. However, this filter exhibits a high passband droop in the passband magnitude characteristic, which must be avoided to prevent the distortion of the decimated signal. In this paper we present the sharpening technique to improve comb passband characteristic. In order to decrease complexity introduced by sharpening, we also consider two-stage structure where the sharpening is applied only at the second stage. Different examples are included to illustrate the benefits of the proposed method.

Jovanovic Dolecek, Gordana

2015-01-01

57

Dual-comb spectroscopy based on quantum-cascade-laser frequency combs.  

PubMed

Dual-comb spectroscopy performed in the mid-infrared-where molecules have their strongest rotovibrational absorption lines-offers the promise of high spectral resolution broadband spectroscopy with very short acquisition times (?s) and no moving parts. Recently, we demonstrated frequency comb operation of a quantum-cascade-laser. We now use that device in a compact, dual-comb spectrometer. The noise properties of the heterodyne beat are close to the shot noise limit. Broadband (15?cm(-1)) high-resolution (80?MHz) absorption spectroscopy of both a GaAs etalon and water vapour is demonstrated, showing the potential of quantum-cascade-laser frequency combs as the basis for a compact, all solid-state, broadband chemical sensor. PMID:25307936

Villares, Gustavo; Hugi, Andreas; Blaser, Stéphane; Faist, Jérôme

2014-01-01

58

Precision spectroscopy of Rb atoms using single comb-line selected from fiber optical frequency comb.  

PubMed

We demonstrated the selection of a single comb-line from an optical frequency comb (OFC) of a mode-locked femtosecond fiber laser with a 250 MHz pulse repetition rate, and applied for precision spectroscopy of Rb atoms at 1529 nm. The single comb-line was selected from the fiber-OFC with a 1.5 GHz mode-spacing using spectral-mode-filtering and femtosecond laser injection-locking. When the repetition rate of the mode-locked femtosecond fiber laser was scanned over the range of 382.6 Hz at 250 MHz, we observed the double-resonance optical pumping spectra of the 5S(1/2)-5P(3/2)-4D(3/2) transition of Rb atoms using the selected comb-line of an OFC scanned over the range of 300 MHz at 196,037,213.8 MHz. PMID:21934948

Moon, Han Seb; Ryu, Han Young; Lee, Sung Hun; Suh, Ho Suhng

2011-08-15

59

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

PubMed Central

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. PMID:24448604

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

2014-01-01

60

Broadband high-resolution X-ray frequency combs  

NASA Astrophysics Data System (ADS)

Optical frequency combs have had a remarkable impact on precision spectroscopy. Enabling this technology in the X-ray domain is expected to result in wide-ranging applications, such as stringent tests of astrophysical models and quantum electrodynamics, a more sensitive search for the variability of fundamental constants, and precision studies of nuclear structure. Ultraprecise X-ray atomic clocks may also be envisaged. In this work, an X-ray pulse-shaping method is proposed to generate a comb in the absorption spectrum of an ultrashort high-frequency pulse. The method employs an optical-frequency-comb laser, manipulating the system's dipole response to imprint a comb on an excited transition with a high photon energy. The described scheme provides higher comb frequencies and requires lower optical-comb peak intensities than currently explored methods, preserves the overall width of the optical comb, and may be implemented using currently available X-ray technology.

Cavaletto, Stefano M.; Harman, Zoltán; Ott, Christian; Buth, Christian; Pfeifer, Thomas; Keitel, Christoph H.

2014-07-01

61

Time sequence photography of Roosters Comb  

Technology Transfer Automated Retrieval System (TEKTRAN)

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...

62

Combe d'Arc Cave Paintings  

NSDL National Science Digital Library

France's Ministry of Culture has placed four high-resolution pictures of last month's newly-discovered Combe d'Arc cave paintings on-line. They are truly exquisite and this may be the only place where you can catch a peek at them.

63

Conformational behavior of diblock comb copolymers.  

PubMed

The conformational behavior of a single diblock copolymer chain with comb blocks is studied by computer simulation. The comb blocks have equal lengths of the backbones and side chains and differ only by the degree of grafting of the side chains. The collapse behavior is studied for two cases: (i) comb diblock copolymer with attracting backbones of the blocks and swollen side chains and (ii) comb diblock copolymer with attracting monomer units of the side chains of the blocks and swollen backbones. In both cases the conformation of a globule with a tail is observed when one of the block collapses while the other stays swollen. At high attraction micellar-type globules are formed. The core of the micelle consists of attracting monomeric units and the soluble segments (side chains or backbones) comprise the corona. It is shown that separation of monomeric units belonging to different blocks can take place both in the core and in the corona regions of the micelle. PMID:19405626

Konovalov, M A; Kramarenko, E Yu; Khokhlov, A R; Reineker, P

2009-04-28

64

Cavity-enhanced dual-comb spectroscopy  

Microsoft Academic Search

The sensitivity of molecular fingerprinting is dramatically improved when the absorbing sample is placed in a high-finesse optical cavity, because the effective path length is increased. When the equidistant lines from a laser frequency comb are simultaneously injected into the cavity over a large spectral range, multiple trace gases may be identified within a few milliseconds. However, efficient analysis of

Birgitta Bernhardt; Akira Ozawa; Patrick Jacquet; Marion Jacquey; Yohei Kobayashi; Thomas Udem; Ronald Holzwarth; Guy Guelachvili; Theodor W. Hänsch; Nathalie Picqué

2010-01-01

65

Safe sex  

MedlinePLUS

Safe sex means taking steps before and during sex that can prevent you from getting an infection, or from ... the skin around the genital area. Before having sex: Get to know your partner and discuss your ...

66

The Rose-comb Mutation in Chickens Constitutes a Structural Rearrangement Causing Both Altered Comb Morphology and Defective Sperm Motility  

PubMed Central

Rose-comb, a classical monogenic trait of chickens, is characterized by a drastically altered comb morphology compared to the single-combed wild-type. Here we show that Rose-comb is caused by a 7.4 Mb inversion on chromosome 7 and that a second Rose-comb allele arose by unequal crossing over between a Rose-comb and wild-type chromosome. The comb phenotype is caused by the relocalization of the MNR2 homeodomain protein gene leading to transient ectopic expression of MNR2 during comb development. We also provide a molecular explanation for the first example of epistatic interaction reported by Bateson and Punnett 104 years ago, namely that walnut-comb is caused by the combined effects of the Rose-comb and Pea-comb alleles. Transient ectopic expression of MNR2 and SOX5 (causing the Pea-comb phenotype) occurs in the same population of mesenchymal cells and with at least partially overlapping expression in individual cells in the comb primordium. Rose-comb has pleiotropic effects, as homozygosity in males has been associated with poor sperm motility. We postulate that this is caused by the disruption of the CCDC108 gene located at one of the inversion breakpoints. CCDC108 is a poorly characterized protein, but it contains a MSP (major sperm protein) domain and is expressed in testis. The study illustrates several characteristic features of the genetic diversity present in domestic animals, including the evolution of alleles by two or more consecutive mutations and the fact that structural changes have contributed to fast phenotypic evolution. PMID:22761584

Boije, Henrik; Bed'hom, Bertrand; Fillon, Valérie; Dorshorst, Ben; Rubin, Carl-Johan; Liu, Ranran; Gao, Yu; Gu, Xiaorong; Wang, Yanqiang; Gourichon, David; Zody, Michael C.; Zecchin, William; Vieaud, Agathe; Tixier-Boichard, Michèle; Hu, Xiaoxiang; Hallböök, Finn; Li, Ning; Andersson, Leif

2012-01-01

67

Stephen C. Pratt Decentralized control of drone comb construction in honey bee colonies  

E-print Network

Stephen C. Pratt Decentralized control of drone comb construction in honey bee colonies Received with two types of comb distinguished by cell size: large cells for rearing males (drone comb) and small of drone comb in a nest is governed by negative feedback from drone comb already constructed. This feedback

Pratt, Stephen

68

High-Temperature Thermoelectric Properties of the Solid–Solution Zintl Phase Eu11Cd6Sb12–xAsx (x < 3)  

SciTech Connect

Zintl phases are compounds that have shown promise for thermoelectric applications. The title solid–solution Zintl compounds were prepared from the elements as single crystals using a tin flux for compositions x = 0, 1, 2, and 3. Eu11Cd6Sb12–xAsx (x < 3) crystallize isostructurally in the centrosymmetric monoclinic space group C2/m (no. 12, Z = 2) as the Sr11Cd6Sb12 structure type (Pearson symbol mC58). Efforts to make the As compositions for x exceeding ?3 resulted in structures other than the Sr11Cd6Sb12 structure type. Single-crystal X-ray diffraction indicates that As does not randomly substitute for Sb in the structure but is site specific for each composition. The amount of As determined by structural refinement was verified by electron microprobe analysis. Electronic structures and energies calculated for various model structures of Eu11Cd6Sb10As2 (x = 2) indicated that the preferred As substitution pattern involves a mixture of three of the six pnicogen sites in the asymmetric unit. In addition, As substitution at the Pn4 site opens an energy gap at the Fermi level, whereas substitution at the other five pnicogen sites remains semimetallic with a pseudo gap. Thermoelectric properties of these compounds were measured on hot-pressed, fully densified pellets. Samples show exceptionally low lattice thermal conductivities from room temperature to 775 K: 0.78–0.49 W/mK for x = 0; 0.72–0.53 W/mK for x = 1; and 0.70–0.56 W/mK for x = 2. Eu11Cd6Sb12 shows a high p-type Seebeck coefficient (from +118 to 153 ? V/K) but also high electrical resistivity (6.8 to 12.8 m?·cm). The value of zT reaches 0.23 at 774 K. The properties of Eu11Cd6Sb12–xAsx are interpreted in discussion with the As site substitution.

Kazem, Nasrin; Xie, Weiwei; Ohno, Saneyuki; Zevalkink, Alexandra; Miller, Gordon J.; Snyder, G. Jeffrey; Kauzlarich, Susan M.

2014-02-11

69

Coherent data transmission with microresonator Kerr frequency combs  

E-print Network

Optical frequency combs enable coherent data transmission on hundreds of wavelength channels and have the potential to revolutionize terabit communications. Generation of Kerr combs in nonlinear integrated microcavities represents a particularly promising option enabling line spacings of tens of GHz, compliant with wavelength-division multiplexing (WDM) grids. However, Kerr combs may exhibit strong phase noise and multiplet spectral lines, and this has made high-speed data transmission impossible up to now. Recent work has shown that systematic adjustment of pump conditions allows generating low phase-noise Kerr combs with singlet spectral lines. Here, by employing an integrated Si3N4 microresonator, we demonstrate that Kerr combs are suited for coherent data transmission with advanced modulation formats that pose stringent requirements on the spectral purity of the optical source. In our experiment, we encode a data stream of 392 Gbit/s on subsequent lines of a Kerr comb using quadrature phase shift keying (...

Pfeifle, Joerg; Wegner, Daniel; Brasch, Victor; Herr, Tobias; Hartinger, Klaus; Li, Jingshi; Hillerkuss, David; Schmogrow, Rene; Holzwarth, Ronald; Freude, Wolfgang; Leuthold, Juerg; Kippenberg, Tobias J; Koos, Christian

2013-01-01

70

Laser frequency combs for astronomical observations  

E-print Network

A direct measurement of the universe's expansion history could be made by observing in real time the evolution of the cosmological redshift of distant objects. However, this would require measurements of Doppler velocity drifts of about 1 centimeter per second per year, and astronomical spectrographs have not yet been calibrated to this tolerance. We demonstrate the first use of a laser frequency comb for wavelength calibration of an astronomical telescope. Even with a simple analysis, absolute calibration is achieved with an equivalent Doppler precision of approximately 9 meters per second at about 1.5 micrometers - beyond state-of-the-art accuracy. We show that tracking complex, time-varying systematic effects in the spectrograph and detector system is a particular advantage of laser frequency comb calibration. This technique promises an effective means for modeling and removal of such systematic effects to the accuracy required by future experiments to see direct evidence of the universe's putative acceleration.

Tilo Steinmetz; Tobias Wilken; Constanza Araujo-Hauck; Ronald Holzwarth; Theodor W. Hänsch; Luca Pasquini; Antonio Manescau; Sandro D'Odorico; Michael T. Murphy; Thomas Kentischer; Wolfgang Schmidt; Thomas Udem

2008-09-09

71

Laser frequency combs for astronomical observations  

E-print Network

A direct measurement of the universe's expansion history could be made by observing in real time the evolution of the cosmological redshift of distant objects. However, this would require measurements of Doppler velocity drifts of about 1 centimeter per second per year, and astronomical spectrographs have not yet been calibrated to this tolerance. We demonstrate the first use of a laser frequency comb for wavelength calibration of an astronomical telescope. Even with a simple analysis, absolute calibration is achieved with an equivalent Doppler precision of approximately 9 meters per second at about 1.5 micrometers - beyond state-of-the-art accuracy. We show that tracking complex, time-varying systematic effects in the spectrograph and detector system is a particular advantage of laser frequency comb calibration. This technique promises an effective means for modeling and removal of such systematic effects to the accuracy required by future experiments to see direct evidence of the universe's putative acceler...

Steinmetz, Tilo; Araujo-Hauck, Constanza; Holzwarth, Ronald; Hänsch, Theodor W; Pasquini, Luca; Manescau, Antonio; D'Odorico, Sandro; Murphy, Michael T; Kentischer, Thomas; Schmidt, Wolfgang; Udem, Thomas

2008-01-01

72

Endless frequency shifting of optical frequency comb lines.  

PubMed

The functional principle of a novel technique for frequency shifting lines of an optical frequency comb is demonstrated. The underlying principle is to shift the carrier frequency by changing the carrier phase within the time span between subsequent pulses of a mode-locked laser used as comb generator. This universal frequency shifter does not require intrusion into the comb generator and provides high agility for arbitrary temporal frequency evolutions. PMID:23482149

Benkler, Erik; Rohde, Felix; Telle, Harald R

2013-03-11

73

Recent advances in ultrafast optical parametric oscillator frequency combs  

NASA Astrophysics Data System (ADS)

We discuss recent advances in the stabilization and application of femtosecond frequency combs based on optical parametric oscillators (OPOs) pumped by femtosecond lasers at 800 and 1060 nm. A method for locking to zero the carrier-envelope-offset of a Ti:sapphire-pumped OPO comb is described. The application of Yb:KYW-laser-pumped dual-combs for mid-infrared spectroscopy is detailed, specifically methane spectroscopy at approximately a 0.7% concentration at 1 atm.

McCracken, Richard A.; Zhang, Zhaowei; Reid, Derryck T.

2014-12-01

74

Frequency comb from a microresonator with engineered spectrum.  

PubMed

We demonstrate that by varying the ratio between the linewidth and dispersion of a whispering gallery mode resonator we are able to control the number N of free spectral ranges separating the first generated comb sidebands from the pump. We observed combs with N = 19 and N = 1. For the comb with N = 1 we have achieved a span of over 200 nm using a 0.4 mm MgF? resonator pumped with 50 mW at 1560 nm. This pump power is a factor of 10 lower than previously reported for combs with comparable bandwidth. PMID:22418543

Grudinin, Ivan S; Baumgartel, Lukas; Yu, Nan

2012-03-12

75

Microresonator-based comb generation without an external laser source.  

PubMed

We demonstrate a fiber-microresonator dual-cavity architecture with which we generate 880 nm of comb bandwidth without the need for a continuous-wave pump laser. Comb generation with this pumping scheme is greatly simplified as compared to pumping with a single frequency laser, and the generated combs are inherently robust due to the intrinsic feedback mechanism. Temporal and radio frequency (RF) characterization show a regime of steady comb formation that operates with reduced RF amplitude noise. The dual-cavity design is capable of being integrated on-chip and offers the potential of a turn-key broadband multiple wavelength source. PMID:24515147

Johnson, Adrea R; Okawachi, Yoshitomo; Lamont, Michael R E; Levy, Jacob S; Lipson, Michal; Gaeta, Alexander L

2014-01-27

76

Universality of comb structures in strong-field QED  

E-print Network

We demonstrate a new mechanism for coherent comb generation in both radiation and matter domains, which is by using strong-field quantum electrodynamics processes. Specifically, we demonstrate this for nonlinear Compton scattering which has the potential to generate frequency combs extending towards the $\\gamma$-ray spectral region as well as combs of ultra-relativistic electrons extending towards the MeV regime. Moreover, we show that coherent energy combs of positrons (or electrons) emerge in laser-induced pair creation processes such as the Breit-Wheeler process, proving the universality of the proposed mechanism.

Katarzyna Krajewska; Jerzy Z. Kaminski

2013-07-20

77

Coherent Raman dual-comb spectroscopy and imaging  

NASA Astrophysics Data System (ADS)

The invention of the optical frequency comb technique has revolutionized the field of precision spectroscopy, providing a way to measure the absolute frequency of any optical transition. Since, frequency combs have become common equipment for frequency metrology. In the last decade, novel applications for the optical frequency comb have been demonstrated beyond its original purpose. Broadband molecular spectroscopy is one of those. One such technique of molecular spectroscopy with frequency combs, dual-comb Fourier transform spectroscopy provides short measurement times with resolution and accuracy. Two laser frequency combs with slightly different repetition frequencies generate pairs of pulses with a linearly-scanned delay between pulses in a pair. The system without moving parts mimics a fast scanning Fourier transform interferometer. The measurement speed may be several orders of magnitude faster than that of a Michelson-based Fourier transform spectrometer, which opens up new opportunities for broadband molecular spectroscopy. Recently, dual-comb spectroscopy has been extended to nonlinear phenomena. A broadband Raman spectrum of molecular fingerprints may be measured within a few tens of microseconds with coherent Raman dual-comb spectroscopy. Raster scanning the sample leads to hyperspectral images. This rapid and broadband label-free vibrational spectroscopy and imaging technique might provide new diagnostic methods in a variety of scientific and industrial fields.

Ideguchi, Takuro; Holzner, Simon; Bernhardt, Birgitta; Guelachvili, Guy; Hänsch, Theodor W.; Picqué, Nathalie

2014-11-01

78

Optical frequency comb with submillihertz linewidth and more than  

E-print Network

actuator (PZT), a fibre Bragg grating (FBG), a polarization-maintaining, large-mode-area fibre (PM LMA here that optical frequency combs produced by high-power fibre lasers reach unprecedented levels demonstrated13,14,16­18 that all-fibre systems could produce high- quality optical frequency combs with average

79

Bonding technologies for silicon scanning mirror having vertical comb fingers  

Microsoft Academic Search

A 1500 micrometers X 1200 micrometers silicon scanning mirror for laser display has been fabricated. This scanning mirror is mainly composed of two structures having vertical comb fingers. By anodic bonding of the silicon wafer and the Pyrex glass substrate, and followed deep ICPRIE (Inductively Coupled Plasma Reactive Ion Etching), isolated comb electrodes were fabricated at the lower structure. But

Jin-Ho Lee; Young-Chul Ko; Byoung-So Choi; Jong-Min Kim; Duk-Young Jeon

2001-01-01

80

Original article Drone production and drone comb utilization  

E-print Network

Original article Drone production and drone comb utilization in colonies of the African honey bee June 1994) Summary — Drone production and drone comb utilization were investigated in naturally, Botswana. Drone production occurred primarily in larger, thriving and swarming colonies that contained

Paris-Sud XI, Université de

81

Continuous comparison of two fiber based fs-frequency combs  

Microsoft Academic Search

Erbium-doped femtosecond fiber lasers are ideal comb generators for optical frequency metrology. We compare two such systems and find agreement within 2×10-16. This is to our knowledge the first thorough test of fiber-based frequency combs.

P. Kubina; P. Adel; T. W. Hansch; R. Holzwarth; H. Schnatz; B. Lipphardt; G. Grosche

2005-01-01

82

Sex Chromosome  

NSDL National Science Digital Library

A sex chromosome is one of the two chromosomes that specify an organism's genetic sex. Humans have two kinds of sex chromosomes, one called X and the other Y. Normal females possess two X chromosomes and normal males one X and one Y.

Darryl Leja (National Human Genome Research Institute REV)

2005-04-14

83

Processing of optical combs with fiber optic parametric amplifiers.  

PubMed

Low noise optical frequency combs consist of equally spaced narrow-linewidth optical tones. They are useful in many applications including, for example, line-by-line pulse shaping, THz generation, and coherent communications. In such applications the comb spacing, extent of spectral coverage, degree of spectral flatness, optical tone power and tone-to-noise ratio represent key considerations. Simultaneously achieving the level of performance required in each of these parameters is often challenging using existing comb generation technologies. Herein we suggest and demonstrate how fiber optic parametric amplifiers can be used to enhance all of these key comb parameters, allowing frequency span multiplication, low noise amplification with simultaneous comb spectrum flattening, and improvement in optical tone-to-noise ratio through various phase insensitive as well as phase sensitive implementations. PMID:22535096

Slavík, R; Kakande, J; Petropoulos, P; Richardson, D J

2012-04-23

84

Adaptive real-time dual-comb spectroscopy  

E-print Network

With the advent of laser frequency combs, coherent light sources that offer equally-spaced sharp lines over a broad spectral bandwidth have become available. One decade after revolutionizing optical frequency metrology, frequency combs hold much promise for significant advances in a growing number of applications including molecular spectroscopy. Despite its intriguing potential for the measurement of molecular spectra spanning tens of nanometers within tens of microseconds at Doppler-limited resolution, the development of dual-comb spectroscopy is hindered by the extremely demanding high-bandwidth servo-control conditions of the laser combs. Here we overcome this difficulty. We experimentally demonstrate a straightforward concept of real-time dual-comb spectroscopy, which only uses free-running mode-locked lasers without any phase-lock electronics, a posteriori data-processing, or the need for expertise in frequency metrology. The resulting simplicity and versatility of our new technique of adaptive dual-com...

Ideguchi, Takuro; Guelachvili, Guy; Picqué, Nathalie; Hänsch, Theodor W

2012-01-01

85

Efficiency optimization for atomic frequency comb storage  

SciTech Connect

We study the efficiency of the atomic frequency comb storage protocol. We show that for a given optical depth, the preparation procedure can be optimize to significantly improve the retrieval. Our prediction is well supported by the experimental implementation of the protocol in a Tm{sup 3+}:YAG crystal. We observe a net gain in efficiency from 10 to 17% by applying the optimized preparation procedure. In the perspective of high bandwidth storage, we investigate the protocol under different magnetic fields. We analyze the effect of the Zeeman and superhyperfine interaction.

Bonarota, M.; Ruggiero, J.; Le Goueet, J.-L.; Chaneliere, T. [Laboratoire Aime Cotton, CNRS-UPR 3321, Univ. Paris-Sud, Bat. 505, F-91405 Orsay Cedex (France)

2010-03-15

86

Comparative study of some characteristics of the semen of RR (rose comb) or rr (single comb) cockerels  

E-print Network

- tory papillae at autopsy. In each semen sample, the volume, the sperm concentration, the total numberComparative study of some characteristics of the semen of RR (rose comb) or rr (single comb 40, avenue du Recteur Pineau, 96022 Poitiers, France. Summary. Comparative studies were made of semen

Paris-Sud XI, Université de

87

Patterns of Electrical Activity in Comb Plates of Feeding Pleurobrachia (Ctenophora)  

Microsoft Academic Search

The electromotor behaviour of ciliary comb plates was studied during prey-stimulated and electrically stimulated feeding by intact Pleurobrachia pileus (Muller). Comb plate electrical activity was recorded by extracellular electrodes attached directly to the cilia; comb plate motility was recorded by high-speed video microscopy. Comb plate electrical activity fell into two distinct classes, identified by waveform and amplitude: (i) excitatory postsynaptic

Anthony G. Moss; Sidney L. Tamm

1993-01-01

88

Cavity-Enhanced Optical Frequency Comb Spectroscopy  

NASA Astrophysics Data System (ADS)

Cavity-enhanced optical frequency comb spectroscopy is a new technique that realizes simultaneously broad spectral coverage and high spectral resolution provided by an optical frequency comb as well as ultrahigh detection sensitivities enabled with a high-finesse optical cavity [1]. These powerful capabilities have been demonstrated in a series of experiments where real-time detection and identification of many different molecular states or species are achieved in a massively parallel fashion [2,3]. We will discuss the principle, technical requirements, and various implementations for this spectroscopic approach, as well as applications that include trace gas detections, human breath analysis, and characterization of cold and ultracold molecules [4,5,6]. References: [1] M. J. Thorpe, K. D. Moll, B. Safdi, and J. Ye, Science 311, 1595 (2006). [2] M. J. Thorpe, D. D. Hudson, K. D. Moll, J. Lasri, and J. Ye, Opt. Lett. 32, 307 (2007). [3] C. Gohle, B. Stein, A. Schliesser, T. Udem, and T. W. Hänsch, Phys. Rev. Lett. 99, 263902 (2007). [4] M. J. Thorpe, D. Balslev-Clausen, M. Kirchner, and J. Ye, Opt. Express. 16, 2387 (2008). [5] M. J. Thorpe and J. Ye, Appl. Phys. B 91, 397 (2008). [6] M. J. Thorpe, F. Adler, K. C. Cossel, M. H. G. de Miranda, and J. Ye, Chem. Phys. Lett. 468, 1 (2009).

Ye, Jun; Thorpe, Michael J.; Adler, Florian; Cossel, Kevin C.

2009-06-01

89

Cavity-enhanced dual-comb spectroscopy  

E-print Network

The sensitivity of molecular fingerprinting is dramatically improved when placing the absorbing sample in a high-finesse optical cavity, thanks to the large increase of the effective path-length. As demonstrated recently, when the equidistant lines from a laser frequency comb are simultaneously injected into the cavity over a large spectral range, multiple trace-gases may be identified within a few milliseconds. Analyzing efficiently the light transmitted through the cavity however still remains challenging. Here, a novel approach, cavity-enhanced frequency comb Fourier transform spectroscopy, fully overcomes this difficulty and measures ultrasensitive, broad-bandwidth, high-resolution spectra within a few tens of $\\mu$s. It could be implemented from the Terahertz to the ultraviolet regions without any need for detector arrays. We recorded, within 18 $\\mu$s, spectra of the 1.0 $\\mu$m overtone bands of ammonia spanning 20 nm with 4.5 GHz resolution and a noise-equivalent-absorption at one-second-averaging per ...

Bernhardt, Birgitta; Jacquet, Patrick; Jacquey, Marion; Kobayashi, Yohei; Udem, Thomas; Holzwarth, Ronald; Guelachvili, Guy; Hänsch, Theodor W; Picqué, Nathalie

2009-01-01

90

Tunable Surface Properties from Bioinspired Comb Copolymers  

NASA Astrophysics Data System (ADS)

A modular polymer system which incorporates multiple functionalities simultaneously while keeping an identical backbone chemistry is a useful tool in determining necessary functionalities for marine antifouling properties. We have investigated the surface properties and antifouling behavior of polypeptoids, a class of non-natural biomimetic polymers based on an N-substituted glycine backbone, that combine many of the advantageous properties of bulk polymers with those of synthetically produced proteins, including controllable chain shape, sequence, and self-assembled structure. Using thiol-ene click chemistry, thiol functionalized amphiphilic peptoid sequences consisting of hydrophilic methoxyethyl and hydrophobic heptafluorobutyl side chains were attached to polystyrene-block-poly(ethylene oxide-stat-allyl glycidyl ether), creating comb-shaped molecules. Near edge X-ray absorption fine structure spectroscopy (NEXAFS) was used to study the surface characteristics as a function of peptoid length and composition. Only 20% of fluorinated groups in the peptoid were sufficient for promoting surface display of the otherwise hydrophilic PEO/peptoid comb block. Antifouling experiments with spores of the green algae Ulva indicated an influence of sequence.

van Zoelen, Wendy; Buss, Hilda; Ellebracht, Nathan; Zuckermann, Ronald; Segalman, Rachel

2013-03-01

91

Silicon-chip mid-infrared frequency comb generation  

NASA Astrophysics Data System (ADS)

Optical frequency combs are a revolutionary light source for high-precision spectroscopy because of their narrow linewidths and precise frequency spacing. Generation of such combs in the mid-infrared spectral region (2–20??m) is important for molecular gas detection owing to the presence of a large number of absorption lines in this wavelength regime. Microresonator-based frequency comb sources can provide a compact and robust platform for comb generation that can operate with relatively low optical powers. However, material and dispersion engineering limitations have prevented the realization of an on-chip integrated mid-infrared microresonator comb source. Here we demonstrate a complementary metal–oxide–semiconductor compatible platform for on-chip comb generation using silicon microresonators, and realize a broadband frequency comb spanning from 2.1 to 3.5??m. This platform is compact and robust and offers the potential to be versatile for use outside the laboratory environment for applications such as real-time monitoring of atmospheric gas conditions.

Griffith, Austin G.; Lau, Ryan K. W.; Cardenas, Jaime; Okawachi, Yoshitomo; Mohanty, Aseema; Fain, Romy; Lee, Yoon Ho Daniel; Yu, Mengjie; Phare, Christopher T.; Poitras, Carl B.; Gaeta, Alexander L.; Lipson, Michal

2015-02-01

92

Digital processing of RF signals from optical frequency combs  

NASA Astrophysics Data System (ADS)

The presented work is focused on digital processing of beat note signals from a femtosecond optical frequency comb. The levels of mixing products of single spectral components of the comb with CW laser sources are usually very low compared to products of mixing all the comb components together. RF counters are more likely to measure the frequency of the strongest spectral component rather than a weak beat note. Proposed experimental digital signal processing system solves this problem by analyzing the whole spectrum of the output RF signal and using software defined radio (SDR) algorithms. Our efforts concentrate in two main areas: Firstly, using digital servo-loop techniques for locking free running continuous laser sources on single components of the fs comb spectrum. Secondly, we are experimenting with digital signal processing of the RF beat note spectrum produced by f-2f 1 technique used for assessing the offset and repetition frequencies of the comb, resulting in digital servo-loop stabilization of the fs comb. Software capable of computing and analyzing the beat-note RF spectrums using FFT and peak detection was developed. A SDR algorithm performing phase demodulation on the f- 2f signal is used as a regulation error signal source for a digital phase-locked loop stabilizing the offset frequency of the fs comb.

Cizek, Martin; Smid, Radek; Buchta, Zden?k.; Mikel, B?etislav; Lazar, Josef; Cip, Ond?ej

2013-01-01

93

Coherent terabit communications with microresonator Kerr frequency combs  

PubMed Central

Optical frequency combs have the potential to revolutionize terabit communications1. Generation of Kerr combs in nonlinear microresonators2 represents a particularly promising option3 enabling line spacings of tens of GHz. However, such combs may exhibit strong phase noise4-6, which has made high-speed data transmission impossible up to now. Here we demonstrate that systematic adjustment of pump conditions for low phase noise4,7-9 enables coherent data transmission with advanced modulation formats that pose stringent requirements on the spectral purity of the comb. In a first experiment, we encode a data stream of 392 Gbit/s on a Kerr comb using quadrature phase shift keying (QPSK) and 16-state quadrature amplitude modulation (16QAM). A second experiment demonstrates feedback-stabilization of the comb and transmission of a 1.44 Tbit/s data stream over up to 300 km. The results show that Kerr combs meet the highly demanding requirements of coherent communications and thus offer an attractive solution towards chip-scale terabit/s transceivers. PMID:24860615

Pfeifle, Joerg; Brasch, Victor; Lauermann, Matthias; Yu, Yimin; Wegner, Daniel; Herr, Tobias; Hartinger, Klaus; Schindler, Philipp; Li, Jingshi; Hillerkuss, David; Schmogrow, Rene; Weimann, Claudius; Holzwarth, Ronald; Freude, Wolfgang; Leuthold, Juerg; Kippenberg, Tobias J.; Koos, Christian

2014-01-01

94

Silicon-chip mid-infrared frequency comb generation.  

PubMed

Optical frequency combs are a revolutionary light source for high-precision spectroscopy because of their narrow linewidths and precise frequency spacing. Generation of such combs in the mid-infrared spectral region (2-20??m) is important for molecular gas detection owing to the presence of a large number of absorption lines in this wavelength regime. Microresonator-based frequency comb sources can provide a compact and robust platform for comb generation that can operate with relatively low optical powers. However, material and dispersion engineering limitations have prevented the realization of an on-chip integrated mid-infrared microresonator comb source. Here we demonstrate a complementary metal-oxide-semiconductor compatible platform for on-chip comb generation using silicon microresonators, and realize a broadband frequency comb spanning from 2.1 to 3.5??m. This platform is compact and robust and offers the potential to be versatile for use outside the laboratory environment for applications such as real-time monitoring of atmospheric gas conditions. PMID:25708922

Griffith, Austin G; Lau, Ryan K W; Cardenas, Jaime; Okawachi, Yoshitomo; Mohanty, Aseema; Fain, Romy; Lee, Yoon Ho Daniel; Yu, Mengjie; Phare, Christopher T; Poitras, Carl B; Gaeta, Alexander L; Lipson, Michal

2015-01-01

95

tantalus , a potential link between Notch signalling and chromatin-remodelling complexes  

Microsoft Academic Search

The tantalus (tan) gene encodes a protein that interacts specifically with the Polycomb\\/trithorax group protein Additional sex combs (ASX). Both loss-of-function and gain-of-function mutations in tan cause tissue-specific defects in the eyes, wing veins and bristles of adult flies. As these defects are also typical for components of the Notch (N) signalling pathway, we wished to determine if TAN interacts

Bruce H. Dietrich; Ping Yang; Henry M. Krause

2005-01-01

96

A Genomic Duplication is Associated with Ectopic Eomesodermin Expression in the Embryonic Chicken Comb and Two Duplex-comb Phenotypes.  

PubMed

Duplex-comb (D) is one of three major loci affecting comb morphology in the domestic chicken. Here we show that the two Duplex-comb alleles, V-shaped (D*V) and Buttercup (D*C), are both associated with a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES). EOMES is a T-box transcription factor that is involved in mesoderm specification during gastrulation. In D*V and D*C chicken embryos we find that EOMES is ectopically expressed in the ectoderm of the comb-developing region as compared to wild-type embryos. The confinement of the ectopic expression of EOMES to the ectoderm is in stark contrast to the causal mechanisms underlying the two other major comb loci in the chicken (Rose-comb and Pea-comb) in which the transcription factors MNR2 and SOX5 are ectopically expressed strictly in the mesenchyme. Interestingly, the causal mutations of all three major comb loci in the chicken are now known to be composed of large-scale structural genomic variants that each result in ectopic expression of transcription factors. The Duplex-comb locus also illustrates the evolution of alleles in domestic animals, which means that alleles evolve by the accumulation of two or more consecutive mutations affecting the phenotype. We do not yet know whether the V-shaped or Buttercup allele correspond to the second mutation that occurred on the haplotype of the original duplication event. PMID:25789773

Dorshorst, Ben; Harun-Or-Rashid, Mohammad; Bagherpoor, Alireza Jian; Rubin, Carl-Johan; Ashwell, Chris; Gourichon, David; Tixier-Boichard, Michèle; Hallböök, Finn; Andersson, Leif

2015-02-01

97

A Genomic Duplication is Associated with Ectopic Eomesodermin Expression in the Embryonic Chicken Comb and Two Duplex-comb Phenotypes  

PubMed Central

Duplex-comb (D) is one of three major loci affecting comb morphology in the domestic chicken. Here we show that the two Duplex-comb alleles, V-shaped (D*V) and Buttercup (D*C), are both associated with a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES). EOMES is a T-box transcription factor that is involved in mesoderm specification during gastrulation. In D*V and D*C chicken embryos we find that EOMES is ectopically expressed in the ectoderm of the comb-developing region as compared to wild-type embryos. The confinement of the ectopic expression of EOMES to the ectoderm is in stark contrast to the causal mechanisms underlying the two other major comb loci in the chicken (Rose-comb and Pea-comb) in which the transcription factors MNR2 and SOX5 are ectopically expressed strictly in the mesenchyme. Interestingly, the causal mutations of all three major comb loci in the chicken are now known to be composed of large-scale structural genomic variants that each result in ectopic expression of transcription factors. The Duplex-comb locus also illustrates the evolution of alleles in domestic animals, which means that alleles evolve by the accumulation of two or more consecutive mutations affecting the phenotype. We do not yet know whether the V-shaped or Buttercup allele correspond to the second mutation that occurred on the haplotype of the original duplication event. PMID:25789773

Dorshorst, Ben; Rubin, Carl-Johan; Ashwell, Chris; Gourichon, David; Tixier-Boichard, Michèle; Hallböök, Finn; Andersson, Leif

2015-01-01

98

CombAlign: a protein sequence comparison algorithm considering recombinations.  

PubMed

The basic linear treatment of sequence comparisons limits the ability of contemporary sequence alignment algorithms to detect non-order-conserving recombinations. Here, we introduce the algorithm combAlign which addresses the assessment of pairwise sequence similarity on non-order-conserving recombinations on a large scale. Emphasizing a two-level approach, combAlign first detects locally well conserved subsequences in a target and a source sequence. Subsequently, the relative placement of alignments is mapped to a graph. Concatenating local alignments to reassemble the target sequence to the fullest extent, the maximum scoring path through the graph denotes the best attainable combAlignment. Parameters influencing this process can be set to meet the user's specific demands. combAlign is applied to examples demonstrating the possibility to reflect evolutionary kinship of proteins even if their domains and motifs are strongly rearranged. PMID:15724278

Wegner, Katja; Jansen, Stephan; Wuchty, Stefan; Gauges, Ralph; Kummer, Ursula

2004-01-01

99

CombFunc: predicting protein function using heterogeneous data sources  

PubMed Central

Only a small fraction of known proteins have been functionally characterized, making protein function prediction essential to propose annotations for uncharacterized proteins. In recent years many function prediction methods have been developed using various sources of biological data from protein sequence and structure to gene expression data. Here we present the CombFunc web server, which makes Gene Ontology (GO)-based protein function predictions. CombFunc incorporates ConFunc, our existing function prediction method, with other approaches for function prediction that use protein sequence, gene expression and protein–protein interaction data. In benchmarking on a set of 1686 proteins CombFunc obtains precision and recall of 0.71 and 0.64 respectively for gene ontology molecular function terms. For biological process GO terms precision of 0.74 and recall of 0.41 is obtained. CombFunc is available at http://www.sbg.bio.ic.ac.uk/combfunc. PMID:22641853

Wass, Mark N.; Barton, Geraint; Sternberg, Michael J. E.

2012-01-01

100

Optimal Sharpening of Compensated Comb Decimation Filters: Analysis and Design  

PubMed Central

Comb filters are a class of low-complexity filters especially useful for multistage decimation processes. However, the magnitude response of comb filters presents a droop in the passband region and low stopband attenuation, which is undesirable in many applications. In this work, it is shown that, for stringent magnitude specifications, sharpening compensated comb filters requires a lower-degree sharpening polynomial compared to sharpening comb filters without compensation, resulting in a solution with lower computational complexity. Using a simple three-addition compensator and an optimization-based derivation of sharpening polynomials, we introduce an effective low-complexity filtering scheme. Design examples are presented in order to show the performance improvement in terms of passband distortion and selectivity compared to other methods based on the traditional Kaiser-Hamming sharpening and the Chebyshev sharpening techniques recently introduced in the literature. PMID:24578674

Troncoso Romero, David Ernesto

2014-01-01

101

Surface induced self-organization of comb-like macromolecules.  

PubMed

We present a review of the theoretical and experimental evidence for the peculiar properties of comb copolymers, demonstrating the uniqueness of these materials among other polymer architectures. These special properties include an increase in stiffness upon increasing side-chain length, the spontaneous curvature of adsorbed combs, rod-globule transition, and specific intramolecular self-assembly. We also propose a theory of chemically heterogeneous surface nanopattern formation in ultrathin films of comblike macromolecules containing two different types (A and B) of incompatible side chains (so-called binary combs). Side chains of the binary combs are strongly adsorbed on a surface and segregated with respect to the backbone. The thickness of surface domains formed by the B side chains is controlled by the interaction with the substrate. We predict the stability of direct and inverse disc-, torus- and stripelike nanostructures. Phase diagrams of the film are constructed. PMID:22003463

Popov, Konstantin I; Palyulin, Vladimir V; Möller, Martin; Khokhlov, Alexei R; Potemkin, Igor I

2011-01-01

102

Surface induced self-organization of comb-like macromolecules  

PubMed Central

Summary We present a review of the theoretical and experimental evidence for the peculiar properties of comb copolymers, demonstrating the uniqueness of these materials among other polymer architectures. These special properties include an increase in stiffness upon increasing side-chain length, the spontaneous curvature of adsorbed combs, rod–globule transition, and specific intramolecular self-assembly. We also propose a theory of chemically heterogeneous surface nanopattern formation in ultrathin films of comblike macromolecules containing two different types (A and B) of incompatible side chains (so-called binary combs). Side chains of the binary combs are strongly adsorbed on a surface and segregated with respect to the backbone. The thickness of surface domains formed by the B side chains is controlled by the interaction with the substrate. We predict the stability of direct and inverse disc-, torus- and stripelike nanostructures. Phase diagrams of the film are constructed. PMID:22003463

Popov, Konstantin I; Palyulin, Vladimir V; Möller, Martin; Khokhlov, Alexei R

2011-01-01

103

Raman-induced Kerr-effect dual-comb spectroscopy  

E-print Network

We report on the first demonstration of nonlinear dual-frequency-comb spectroscopy. In multi-heterodyne femtosecond Raman-induced Kerr-effect spectroscopy, the Raman gain resulting from the coherent excitation of molecular vibrations by a spectrally-narrow pump is imprinted onto the femtosecond laser frequency comb probe spectrum. The birefringence signal induced by the nonlinear interaction of these beams and the sample is heterodyned against a frequency comb local oscillator with a repetition frequency slightly different from that of the comb probe. Such time-domain interference provides multiplex access to the phase and amplitude Raman spectra over a broad spectral bandwidth within a short measurement time. Experimental demonstration, at a spectral resolution of 200 GHz, a measurement time of 293 {\\mu}s and a sensitivity of 10^-6, is given on liquid samples exhibiting a C-H stretch Raman shift.

Ideguchi, Takuro; Guelachvili, Guy; Hänsch, Theodor W; Picqué, Nathalie

2012-01-01

104

Diffraction and frequency combs in MeV region  

NASA Astrophysics Data System (ADS)

The optical frequency comb has become an indispensable tool for high precision spectroscopy. Also experiments in the field of ultrafast physics rely on the frequency comb technique to generate precisely controlled attosecond optical pulses by means of the high-order harmonic generation. However, in order to generate even shorter laser pulses or to apply this technique in investigations of nuclear structure, combs of frequencies of the order of MeV are necessary. It seems that it may not be possible to achieve such photon energies by high-order harmonic generation. In this context the possibility of the generation of Thomson and Compton-based frequency combs is presented. Diffraction of generated radiation by a sequence of laser pulses and its analogy to the diffraction grating is elucidated.

Krajewska, Katarzyna; Kami?ski, Jerzy Z.

2014-12-01

105

Flow-Through Comb Electroporation Device for Delivery of Macromolecules  

E-print Network

We present a microfluidic electroporation device with a comb electrode layout fabricated in polydimethylsiloxane (PMDS) and glass. Characterization experiments with HeLa cells and fluorescent dextran show efficient delivery ...

Adamo, Andrea

106

Adaptive real-time dual-comb spectroscopy  

PubMed Central

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

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

2014-01-01

107

Adaptive real-time dual-comb spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

108

Dynamics of the modulational instability in microresonator frequency combs  

NASA Astrophysics Data System (ADS)

A study is made of frequency-comb generation described by the driven and damped nonlinear Schrödinger equation on a finite interval. It is shown that frequency-comb generation can be interpreted as a modulational instability of the continuous-wave pump mode, and a linear stability analysis, taking into account the cavity boundary conditions, is performed. Further, a truncated three-wave model is derived, which allows one to gain additional insight into the dynamical behavior of the comb generation. This formalism describes the pump mode and the most unstable sideband and is found to connect the coupled mode theory with the conventional theory of modulational instability. An in-depth analysis is done of the nonlinear three-wave model. It is demonstrated that stable frequency-comb states can be interpreted as attractive fixed points of a dynamical system. The possibility of soft and hard excitation states in both the normal and the anomalous dispersion regime is discussed. Investigations are made of bistable comb states and the dependence of the final state on the way the comb has been generated. The analytical predictions are verified by means of direct comparison with numerical simulations of the full equation and the agreement is discussed.

Hansson, T.; Modotto, D.; Wabnitz, S.

2013-08-01

109

Treatment of head lice (Pediculus humanus capitis) infestation: Is regular combing alone with a special detection comb effective at all levels?  

PubMed

Head lice infestation (HLI) caused by Pediculus humanus capitis has been a public health problem worldwide. Specially designed combs are used to identify head lice, while anti-lice products are applied on the scalp for treatment. In the present study, we aimed to test whether combing only by precision detection comb (PDC) or metal pin comb (MPC) could be effective alternatives to the use of anti-lice products in children. A total of 560 children from two rural schools in Turkey were screened. In the PDC trial, children were combed every second day for 14 days, while in the MPC trial, combing was performed once in every four days for 15 days. Children were divided into two groups (dry combing and wet combing) for both trials and results were compared. The results showed no significant differences between dry and wet combing strategies for both combs for the removal of head lice (p?>?0.05). The number of adult head lice declined significantly on each subsequent combing day in both approaches, except on day 15 in the MPC trial. In the end, no louse was found in 54.1 and 48.9 % of children in the PDC and MPC trials, respectively. Since family members of infested children were not available, they were not checked for HLI. Four times combing within 2 weeks with MPC combs was found effective for both treatment of low HLI and prevention of heavy HLI. In conclusion, regular combing by special combs decreases HLI level in children and is safely applicable as long-term treatment. PMID:25604670

Kurt, Özgür; Balc?o?lu, I Cüneyt; Limoncu, M Emin; Girginkarde?ler, Nogay; Arserim, Süha K; Görgün, Serhan; Oyur, Tuba; Karaku?, Mehmet; Düzyol, Didem; Gökmen, Aysegül Aksoy; Kitapç?o?lu, Gül; Özbel, Yusuf

2015-04-01

110

Sex Offender Registration Information Sex Offender Registration  

E-print Network

Sex Offender Registration Information Sex Offender Registration In accordance to the "Campus Sex Police Sex Offender Registry. This act requires institutions of higher education to issue a statement sex offenders may be obtained. It also requires sex offenders already required to register in a State

Escher, Christine

111

Safe sex  

NSDL National Science Digital Library

There are many diseases that humans can contract through sexual contact with each other. Humans can lower their risk of contracting these diseases by practicing safe sex techniques if they choose to participate in those kinds of actions.

Olivia Worland (Purdue University; Biological Sciences)

2008-07-09

112

Sex work and sex trafficking.  

PubMed

Preventing HIV infection and other sexually transmitted diseases (STDs), as well as sexual and physical violence, are major occupational health and safety concerns for prostitutes. Considerable evidence shows that anti-prostitution laws facilitate violence and abuse against prostitutes and may increase their risk of contracting HIV/STDs. For example, police often take advantage of existing laws against prostitution to demand money or sex. In general, the strict enforcement of anti-prostitution laws marginalizes prostitutes from services which could help them avoid abuse and promotes an environment in which prostitutes must take risks to avoid detection and arrest. One strategy to improve prostitutes' lives would therefore be to remove laws which prevent them from working safely and from travelling abroad to work legally. Projects in which prostitutes are actively involved have helped break down stereotypes against prostitutes, while police-sex worker liaison projects in Scotland and Australia have led to higher levels of reporting of crimes against prostitutes. The Network of Sex Work Projects (NSWP), an organization which links sex worker health programs around the world, has found that the incidence of HIV/STDs among prostitutes is lowest when they have control over their work conditions; access to condoms, lubricants, and other safe sex materials; and respect of their basic human and legal rights. People need to understand that consensual involvement in sex work is different from forced sex trafficking. PMID:12348692

Ditmore, M; Saunders, P

1998-01-01

113

Comb Polymer Architectures for Versatile Nanoparticle Assembly  

NASA Astrophysics Data System (ADS)

Nanoparticles are a material of interest in photovoltaic research due to their optical absorption properties. However, there have been many challenges for device fabrication. It has been difficult to produce continuous, homogenous films, and successes in this area have been highly dependent on the actual nanoparticles used, and have thus been hard to apply generally to different materials of interest. We show how this challenge can be overcome using a comb polymer architecture. Here, pentadecyl phenol small molecules are hydrogen bonded to polyvinyl pyridine. This alkyl moiety produced is compatible with the ligand shells of many nanomaterials. We incorporated these small molecules and nanoparticles into polystrene-polyvinyl pyridine block copolymers. This strategy was successful for assembling nanoparticles made out of a variety of materials, without special considerations for the actual core material or morphology. Following these successes in bulk samples we extended our studies to thin films of these composites. Here, the morphology is controlled by the interfacial interactions. These materials have the potential to be used for photovoltaic devices, as they are easily solution-processible. This strategy is generally applicable with the choice of small molecule mediating interactions with any desired nanomaterial.

Mastroianni, Alexander; Thorkelsson, Kari; Zhao, Yue; Luther, Joseph; Millstone, Jill; Alivisatos, Paul; Frechet, Jean; Xu, Ting

2009-03-01

114

Self-referenced 1.5 [mu]m fiber frequency combs at GHz repetition rates  

E-print Network

Tremendous advances in recent years to the optical frequency comb, particularly frequency combs deriving from solid-state and fiber architectures, have enabled a host of important new applications to emerge - applications ...

Chao, David, Ph. D. Massachusetts Institute of Technology

2012-01-01

115

X-ray frequency combs from optically controlled resonance fluorescence  

NASA Astrophysics Data System (ADS)

An x-ray pulse-shaping scheme is put forward for imprinting an optical frequency comb onto the radiation emitted on a driven x-ray transition, thus producing an x-ray frequency comb. A four-level system is used to describe the level structure of N ions driven by narrow-bandwidth x rays, an optical auxiliary laser, and an optical frequency comb. By including many-particle enhancement of the emitted resonance fluorescence, a spectrum is predicted consisting of equally spaced narrow lines which are centered on an x-ray transition energy and separated by the same tooth spacing as the driving optical frequency comb. Given an x-ray reference frequency, our comb could be employed to determine an unknown x-ray frequency. While relying on the quality of the light fields used to drive the ensemble of ions, the model has validity at energies from the 100 eV to the keV range.

Cavaletto, Stefano M.; Harman, Zoltán; Buth, Christian; Keitel, Christoph H.

2013-12-01

116

Brood comb as a humidity buffer in honeybee nests  

NASA Astrophysics Data System (ADS)

Adverse environmental conditions can be evaded, tolerated or modified in order for an organism to survive. During their development, some insect larvae spin cocoons which, in addition to protecting their occupants against predators, modify microclimatic conditions, thus facilitating thermoregulation or reducing evaporative water loss. Silk cocoons are spun by honeybee ( Apis mellifera) larvae and subsequently incorporated into the cell walls of the wax combs in which they develop. The accumulation of this hygroscopic silk in the thousands of cells used for brood rearing may significantly affect nest homeostasis by buffering humidity fluctuations. This study investigates the extent to which the comb may influence homeostasis by quantifying the hygroscopic capacity of the cocoons spun by honeybee larvae. When comb containing cocoons was placed at high humidity, it absorbed 11% of its own mass in water within 4 days. Newly drawn comb composed of hydrophobic wax and devoid of cocoons absorbed only 3% of its own mass. Therefore, the accumulation of cocoons in the comb may increase brood survivorship by maintaining a high and stable humidity in the cells.

Ellis, Michael B.; Nicolson, Sue W.; Crewe, Robin M.; Dietemann, Vincent

2010-04-01

117

Structure and effective interactions of comb polymer nanocomposite melts  

NASA Astrophysics Data System (ADS)

In this work, the structure and effective interactions of branched comb polymer nanocomposite (PNC) melts are investigated by using the polymer reference interaction site model (PRISM) integral equation theory. It is observed that the nanoparticle contact (bridging) aggregation is formed when the nanoparticle-monomer attraction strength is relatively weak (large) in comb PNCs. The organization states of aggregation for the moderate nanoparticle-monomer attraction strength can be well suppressed by the comb polymer architecture, while the bridging structure for relatively large attraction is obviously promoted. With the increase of the particle volume fraction, the organization states of bridging-type structure become stronger and tighter; however, this effect is weaker than that of the nanoparticle-monomer attraction strength. When the particle volume fraction and moderate nanoparticle-monomer attraction strength are fixed, the effects of degree of polymerization, side chain number, side chain length, and nanoparticle-monomer size ratio on the organization states of PNC melts are not prominent and the nanoparticles can well disperse in comb polymer. All the observations indicate that the present PRISM theory can give a detailed description of the comb PNC melts and assist in future design control of new nanomaterials.

Xu, Qinzhi; Xu, Mengjin; Feng, Yancong; Chen, Lan

2014-11-01

118

High-aspect ratio vertical comb-drive actuator with small self-aligned finger gaps  

Microsoft Academic Search

A vertical comb-drive actuator with thin, high-aspect ratio comb fingers and small self-aligned gaps is presented. Key to the actuator design is the self-aligned, offset comb-drive fingers, which are fabricated with small gaps (?2 ?m) using a single lithography step. The offset comb fingers are fabricated using two thick conducting layers separated by a thin dielectric layer. The lower fingers

Edwin T. Carlen; Khee-Hang Heng; S. Bakshi; A. Pareek; C. H. Mastrangelo

2005-01-01

119

Comparative reproduction of Varroa destructor in different types of Russian and Italian honey bee combs  

Technology Transfer Automated Retrieval System (TEKTRAN)

We studied whether or not older comb supported less varroa reproduction in both Russian and Italian honey bees, whether Russian bees produced comb which inhibited varroa reproduction and whether comb foundation contained enough acaricides to influence varroa reproduction. The major differences foun...

120

Reciprocal interactions between honeybees and combs in the integration of some colony  

E-print Network

Review Reciprocal interactions between honeybees and combs in the integration of some colony in studies of the reciprocal interactions between honeybees and their combs are reviewed. Wax secretion in the waggle dance and recruitment of new foragers. © Inra/ DIB/AGIB/Elsevier, Paris honeybee / combs

Paris-Sud XI, Université de

121

Fibre-optic comb filter with tunable central wavelength and channel isolation at  

E-print Network

Fibre-optic comb filter with tunable central wavelength and channel isolation at sub and compact tunable fibre-optic comb filter with the tuning implemented based on two electro-optic phase years in the development of electronically tunable fibre-optic comb filters. Potential applications

Yao, Jianping

122

Fiber-laser-based frequency comb with a tunable repetition rate  

E-print Network

Fiber-laser-based frequency comb with a tunable repetition rate B. R. Washburn, R. W. Fox, and N. R Abstract: A phase-locked, self-referenced frequency comb generated by a mode-locked fiber soliton laser and length metrology, synchronization of different fiber laser-based frequency combs, and the generation

Washburn, Brian

123

Elimination of pump-induced frequency jitter on fiber-laser frequency combs  

E-print Network

Elimination of pump-induced frequency jitter on fiber-laser frequency combs J. J. McFerran, W. C. ID 68330) Optical frequency combs generated by femtosecond fiber lasers typically exhibit significant- veloped with Ti:sapphire lasers, frequency combs have been recently demonstrated with mode-locked fiber

Washburn, Brian

124

Calibration of an astrophysical spectrograph below 1 m/s using a laser frequency comb  

E-print Network

We deployed two wavelength calibrators based on laser frequency combs (“astro-combs”) at an astronomical telescope. One astro-comb operated over a 100 nm band in the deep red (~ 800 nm) and a second operated over a 20 nm ...

Phillips, David F.

125

The effect of drone comb on a honey bee colony'sproduction of honey  

Microsoft Academic Search

This study examined the impact on a colony's honey production of providing it with a nat- ural amount (20%) of drone comb. Over 3 summers, for the period mid May to late August, I mea- sured the weight gains of 10 colonies, 5 with drone comb and 5 without it. Colonies with drone comb gained only 25.2 ± 16.0 kg

Thomas D. Seeley

2002-01-01

126

Original article The effect of drone comb on a honey bee colony's  

E-print Network

Original article The effect of drone comb on a honey bee colony's production of honey* Thomas D on a colony's honey production of providing it with a nat- ural amount (20%) of drone comb. Over 3 summers, for the period mid May to late August, I mea- sured the weight gains of 10 colonies, 5 with drone comb and 5

Paris-Sud XI, Université de

127

Multi-band Coherent Optical OFDM Receiver Enabled by Optical Frequency Combs  

E-print Network

the entire bandwidth of the comb lines. The comb lines pass through a spectral demultiplexer (demux), optical and the optical OFDM signal go through respective demuxes, so that each spectral slice of the OFDM signal and its spectra at various stages. PC: polarization controller. (a) (b) Comb Generator DemuxDemux MuxMux I1 Q1

Kolner, Brian H.

128

Intro Comb Anal Prob Higher Dim Other Problems Moments and Densities of Short Random Walks  

E-print Network

Intro Comb Anal Prob Higher Dim Other Problems Moments and Densities of Short Random Walks New, 2014 Revised: 27-11-14 JMB/JW Short Random Walks #12;Intro Comb Anal Prob Higher Dim Other Problems and early career researchers. JMB/JW Short Random Walks #12;Intro Comb Anal Prob Higher Dim Other Problems

Borwein, Jonathan

129

Quantum cascade laser combs: effects of modulation and dispersion.  

PubMed

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. PMID:25835922

Villares, Gustavo; Faist, Jérôme

2015-01-26

130

Noise-immune cavity-enhanced optical frequency comb spectroscopy.  

PubMed

We present a new method of optical frequency comb spectroscopy that combines cavity enhancement with frequency modulation to obtain immunity to laser frequency-to-amplitude noise conversion by the cavity modes and, thus, high absorption sensitivity over a broad spectral range. A frequency comb is locked to a cavity with a free spectral range (FSR) equal to 4/3 times the repetition rate of the laser, and phase-modulated at a frequency equal to the cavity FSR. The transmitted light is analyzed by a Fourier transform spectrometer with a high bandwidth detector. Phase-sensitive detection of the interferogram yields a noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS) signal. In the first demonstration, we record NICE-OFCS signals from the overtone CO2 band at 1575 nm with absorption sensitivity of 4.3×10(-10) cm(-1) Hz(-1/2) per spectral element, close to the shot noise limit. PMID:25166067

Khodabakhsh, Amir; Abd Alrahman, Chadi; Foltynowicz, Aleksandra

2014-09-01

131

A quadratic-shaped-finger comb parametric resonator  

NASA Astrophysics Data System (ADS)

A large-stroke (8 µm) parametric resonator excited by an in-plane ‘shaped-finger’ electrostatic comb drive is fabricated using a 15 µm thick silicon-on-insulator microelectromechanical systems (SOI-MEMS) process. A quadratic capacitance-engagement response is synthesized by engineering a custom-shaped comb finger profile. A folded-flexure suspension allows lateral motion while constraining rotational modes. The excitation of the nonlinear parametric resonance is realized by selecting an appropriate combination of the linear and cubic electrostatic stiffness coefficients through a specific varying-gap comb-finger design. The large-amplitude parametric resonance promotes high signal-to-noise ratio for potential use in sensitive chemical gravimetric sensors, strain gauges, and mode-matched gyroscope applications.

Guo, Congzhong; Fedder, Gary K.

2013-09-01

132

Astro-comb calibration of an Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

We describe recent work calibrating a cross-dispersed spectrograph with an "astro-comb" i.e., a high repetition rate, octave spanning femtosecond laser frequency comb; and a filter cavity suppressing laser modes to match the resolution of the spectrograph. Our astro-comb provides ~1500 evenly spaced (~0.6 A) calibration lines of roughly 100 nW per line between 7800 and 8800 Angstroms. The calibration lines of the laser are stabilized to atomic clocks which can be referenced to GPS providing intrinsic stability of the source laser below 1 cm/s in stellar radial velocity sensitivity, as well as long term stability and reproducibility over years. We present calibration of the TRES spectrograph at the 1.5 m telescope at the Fred L Whipple Observatory below 1 m/s radial velocity sensitivity in six orders from 7800-8800 A.

Li, C.-H.; Phillips, D. F.; Glenday, A. G.; Benedick, A. J.; Chang, G.; Chen, L.-J.; Cramer, C.; Furesz, G.; Kärtner, F. X.; Sasselov, D.; Szentgyorgyi, A.; Walsworth, R. L.

2010-07-01

133

Repetition rate multiplication of a femtosecond frequency comb  

NASA Astrophysics Data System (ADS)

This paper presents the progress in the development of two Fabry-Pérot filter cavities for repetition rate multiplication of two femtosecond frequency combs. The optical design of both setups consists of mode matching optics and a resonant cavity for the repetition rate multiplication. In one case, the cavity consists of two dielectric mirrors with near-zero group velocity dispersion and in the other of two silver coated mirrors. We demonstrate multiplication of a 1 GHz repetition rate to 10 GHz for a Ti:Sa femtosecond frequency comb with central wavelength around 820 nm and of 250 MHz repetition rate to 1 GHz for a Er-doped fiber femtosecond frequency comb with central wavelength around 1560 nm.

Lešundák, Adam; Šmíd, Radek; Voigt, Dirk; ?ížek, Martin; van den Berg, Steven; ?íp, Ond?ej

2015-01-01

134

The generation of Continuous-Variable Entanglement Frequency Comb  

NASA Astrophysics Data System (ADS)

Continuous-variable (CV) entanglement frequency comb can be produced by enhanced Raman scattering in an above-threshold optical oscillator cavity in which a hexagonally-poled LiTaO3 crystal resides as a Raman gain medium. The Stokes and anti-Stokes Raman signals are enhanced by a coupled quasi-phase-matching optical parametric process and the entanglement natures among these Raman signals and pump are demonstrated by applying a sufficient inseparability criterion for CV entanglement. Such entanglement frequency comb source with different frequencies and continuously tunable frequency interval may be very significant for the applications in quantum communication and networks.

Yu, Youbin; Cheng, Xiaomin; Wang, Huaijun; Shi, Zhongtao; Zhao, Junwei; Ji, Fengmin; Yin, Zhi; Wang, Yajuan

2015-01-01

135

Frequency-Comb-Assisted Terahertz Quantum Cascade Laser Spectroscopy  

NASA Astrophysics Data System (ADS)

We report a metrological-grade THz spectroscopy based on the combination of a THz frequency-comb synthesizer (FCS) and a THz quantum cascade laser (QCL). The QCL, emitting at 2.5 THz, is phase locked to the free-space THz FCS, and its frequency is swept across a methanol transition by tuning the comb-repetition rate, which is ultimately disciplined by the Cs primary frequency standard. The absolute frequency scale provides an uncertainty of a few parts in 10-11 on the laser frequency and 10-9 on the line-center determination, ranking this technique among the most precise ever developed in the THz range.

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

2014-04-01

136

Routes to spatiotemporal chaos in Kerr optical frequency combs  

SciTech Connect

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.

Coillet, Aurélien; Chembo, Yanne K., E-mail: yanne.chembo@femto-st.fr [Optics Department, FEMTO-ST Institute CNRS UMR6174, 16 Route de Gray, 25030 Besançon cedex (France)

2014-03-15

137

Routes to spatiotemporal chaos in Kerr optical frequency combs  

NASA Astrophysics Data System (ADS)

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.

Coillet, Aurélien; Chembo, Yanne K.

2014-03-01

138

A helical binary comb with a long helical period  

NASA Astrophysics Data System (ADS)

A helical binary comb with a large helical period is considered as a slow-wave structure for high-power traveling wave tubes. Results are presented on the wavelength dependence of the delay factor and the coupling resistance in the 7-15-cm-wave range for different variants of such structures; as well as on the contribution of powers of the comb spatial harmonics with numbers n = -1 and +1 to the power flux through the interaction-channel cross section.

Vanke, V. A.; Konnov, A. V.

1988-07-01

139

The generation of Continuous-Variable Entanglement Frequency Comb  

PubMed Central

Continuous-variable (CV) entanglement frequency comb can be produced by enhanced Raman scattering in an above-threshold optical oscillator cavity in which a hexagonally-poled LiTaO3 crystal resides as a Raman gain medium. The Stokes and anti-Stokes Raman signals are enhanced by a coupled quasi-phase-matching optical parametric process and the entanglement natures among these Raman signals and pump are demonstrated by applying a sufficient inseparability criterion for CV entanglement. Such entanglement frequency comb source with different frequencies and continuously tunable frequency interval may be very significant for the applications in quantum communication and networks. PMID:25600617

Yu, Youbin; Cheng, Xiaomin; Wang, Huaijun; Shi, Zhongtao; Zhao, Junwei; Ji, Fengmin; Yin, Zhi; Wang, Yajuan

2015-01-01

140

Mid-infrared frequency comb for broadband high precision and sensitivity molecular spectroscopy.  

PubMed

We report on the experimental demonstration of the metrological and spectroscopic performances of a mid-infrared comb generated by a nonlinear downconversion process from a Ti:sapphire-based near-infrared comb. A quantum cascade laser at 4330 nm was phase-locked to a single tooth of this mid-infrared comb and its frequency-noise power spectral density was measured. The mid-infrared comb itself was also used as a multifrequency highly coherent source to perform ambient air direct comb spectroscopy with the Vernier technique, by demultiplexing it with a high-finesse Fabry-Perot cavity. PMID:25166071

Galli, I; Bartalini, S; Cancio, P; Cappelli, F; Giusfredi, G; Mazzotti, D; Akikusa, N; Yamanishi, M; De Natale, P

2014-09-01

141

A stable frequency comb directly referenced to rubidium electromagnetically induced transparency and two-photon transitions  

SciTech Connect

We demonstrate an approach to create a stable erbium-fiber-based frequency comb at communication band by directly locking the combs to two rubidium atomic transitions resonances (electromagnetically induced transparency absorption and two-photon absorption), respectively. This approach directly transfers the precision and stability of the atomic transitions to the comb. With its distinguishing feature of compactness by removing the conventional octave-spanning spectrum and f-to-2f beating facilities and the ability to directly control the comb's frequency at the atomic transition frequency, this stable optical comb can be widely used in optical communication, frequency standard, and optical spectroscopy and microscopy.

Hou, Dong; Wu, Jiutao; Zhang, Shuangyou; Ren, Quansheng; Zhang, Zhigang; Zhao, Jianye, E-mail: zhaojianye@pku.edu.cn [Department of Electronics, Peking University, Beijing, 100871 (China)

2014-03-17

142

Astronomical spectrograph calibration with broad-spectrum frequency combs  

Microsoft Academic Search

.  Broadband femtosecond-laser frequency combs are filtered to spectrographically resolvable frequency-mode spacing, and limitations\\u000a of using cavities for spectral filtering are considered. Data and theory are used to show implications relevant to spectrographic\\u000a calibration of high-resolution, astronomical spectrometers.

D. A. Braje; M. S. Kirchner; S. Osterman; T. Fortier; S. A. Diddams

2008-01-01

143

Noise-induced linewidth in frequency combs Mark J. Ablowitz  

E-print Network

combs are a ubiquitous tool in time and frequency metrology. They are generated by trains of evenly- precedented stability. This breakthrough has revolu- tionized the field of frequency metrology, since it al. The spectrum of N successively emitted pulses is F n=1 N E t - Tn ei ne-i ct + c.c. = E^ ~ S^ ~ + c.c., 1 where

Ilan, Boaz

144

Wax combs mediate nestmate recognition by guard honeybees  

E-print Network

Wax combs mediate nestmate recognition by guard honeybees PATRIZIA D'ETTORRE*, TOM WENSELEERS of colony odour in the honeybee, Apis mellifera. However, many of these studies were conducted). The honeybee, Apis mellifera, is an important model sys- tem for studying nestmate recognition and its

Wenseleers, Tom

145

Reclassification of the polyphyletic genus Prosthecomicrobium to form two novel genera, Vasilyevaea gen. nov. and Bauldia gen. nov. with four new combinations: Vasilyevaea enhydra comb. nov., Vasilyevaea mishustinii comb. nov., Bauldia consociata comb. nov. and Bauldia litoralis comb. nov.  

PubMed Central

Species of the genus Prosthecomicrobium are noted for their numerous cellular appendages or prosthecae that extend from the cells. This investigation confirms that the genus is polyphyletic based on an extensive analysis of the 16S rRNA gene sequences of several named species of the genus. The analyses indicate that some Prosthecomicrobium species are more closely related to non-prosthecate genera, including Devosia, Labrenzia, Blastochloris, Methylosinus, Mesorhizobium and Kaistia, than they are to other species of the genus Prosthecomicrobium. For this reason, two of the Prosthecomicrobium clades which are polyphyletic with the type species, Prosthecomicrobium pneumaticum, are renamed as new genera. The currently named species Prosthecomicrobium enhydrum, Prosthecomicrobium mishustinii, Prosthecomicrobium consociatum and Prosthecomicrobium litoralum are reclassified in two new genera, Vasilyevaea gen. nov. and Bauldia gen. nov. with four new combinations: Vasilyevaea enhydra comb. nov. (the type species) and Vasilyevaea mishustinii comb. nov., and Bauldia consociata comb. nov. and Bauldia litoralis comb. nov. (the type species). The type strain of Vasilyevaea enhydra is strain 9bT (=ATCC 23634T =VKM B-1376T). The type strain of the other species in this genus is Vasilyevaea mishustinii strain 17T (=VKM B-2499T =CCM 7569T). The type strain of Bauldia litoralis is strain 524-16T (= NCIB 2233T =ATCC 35022T). The type strain of the other species in this genus is Bauldia consociata strain 11T (=VKM B-2498T =CCM 7594T). PMID:20118292

Yee, Benjamin; Oertli, Gary E.; Fuerst, John A.; Staley, James T.

2010-01-01

146

Bonding of silicon scanning mirror having vertical comb fingers  

NASA Astrophysics Data System (ADS)

A 1500 ?m × 1200 ?m silicon scanning mirror has been fabricated by using anodic bonding and flip chip bonding. This scanning mirror is mainly composed of two structures having vertical comb fingers. By anodic bonding between the silicon wafer and the Pyrex glass substrate, and following deep inductively coupled plasma reactive ion etching (ICPRIE), isolated comb electrodes were fabricated at the lower structure. However, gold signal lines for electrical connection to the electrodes, which were inserted between silicon and Pyrex glass, were damaged during anodic bonding. This problem was solved by using the proposed processes and signal lines were successfully fabricated with the contact resistance below several tens of ohms. By flip chip bonding, the upper and lower structures having vertical comb fingers were assembled. Vertical comb fingers of two structures were aligned with a microscope and the frames of two structures were bonded at 300 °C for 20 s using the eutectic bonding material - electroplated AuSn. Finally, the scanning mirror was successfully fabricated and could be used for laser display as a galvanometric vertical scanner.

Lee, Jin-Ho; Ko, Young-Chul; Choi, Byoung-So; Kim, Jong-Min; Jeon, Duk Young

2002-09-01

147

Bonding technologies for silicon scanning mirror having vertical comb fingers  

NASA Astrophysics Data System (ADS)

A 1500 micrometers X 1200 micrometers silicon scanning mirror for laser display has been fabricated. This scanning mirror is mainly composed of two structures having vertical comb fingers. By anodic bonding of the silicon wafer and the Pyrex glass substrate, and followed deep ICPRIE (Inductively Coupled Plasma Reactive Ion Etching), isolated comb electrodes were fabricated at the lower structure. But in this anodic bonding, gold signal lines for electrical connection to the electrodes, which were inserted between silicon and Pyrex glass, were cut off by mechanical pressure or damaged to agglomerate by diffusion. To remove these phenomena, Pyrex glass was trenched about 2000 Angstroms in depth in the shape of signal lines, and Cr/Au signal lines were formed along the etched grooves about 500 Angstroms/3500 Angstroms in depth, and then annealed at 400 degree(s)C, N2 atmosphere, for 1 hour before anodic bonding. As a result, gold signal lines were successfully fabricated and the contact resistance was acquired below several tens ohms. By flip chip bonding, the upper and lower structure having vertical comb fingers were assembled. Vertical comb fingers of two structures were aligned with a microscope and the frames of two structures were bonded at 300 degree(s)C for 20 sec. using the eutectic bonding material, electroplated AuSn. Using these bonding technologies, the scanning mirror was successfully fabricated and it could be used for laser display as a galvanometric vertical scanner.

Lee, Jin-Ho; Ko, Young-Chul; Choi, Byoung-So; Kim, Jong-Min; Jeon, Duk-Young

2001-11-01

148

Adaptive dual-comb spectroscopy in the green region  

E-print Network

Dual-comb spectroscopy is extended to the visible spectral range with a set-up based on two frequency-doubled femtosecond ytterbium-doped fiber lasers. The dense rovibronic spectrum of iodine around 19240 cm-1 is recorded within 12 ms at Doppler-limited resolution with a simple scheme that only uses free-running femtosecond lasers.

Ideguchi, Takuro; Guelachvili, Guy; Hänsch, Theodor W; Picqué, Nathalie

2012-01-01

149

Phone Sex  

E-print Network

Phone Se by Flamingo art by KOZ PrmtedinUSA $SJ fS wv) p?l iSI PHCNE %t\\ By flamingo Illustrated by KOZ Editors: Tosya Stohn La Gavia Text & Titles: Jazz Printer: Kinko's ofGrand Rapids, MI Authorized Distributor TbGavia Flamingo Layout & Binding: Tosya Stohn Publisher: Bodacious Press PHONE SEX by Flamingo Copyright? May 1995. All rights reserved. No part of this publication may be reproduced without...

Flamingo

1995-01-01

150

A frequency comb calibrated solar atlas  

NASA Astrophysics Data System (ADS)

Context. The solar spectrum is a primary reference for the study of physical processes in stars and their variation during activity cycles. High resolution spectra of the Sun are easily obtained from spatially selected regions of the solar disk, while those taken over the integrated disk are more problematic. However, a proxy can be obtained by using solar light reflected by small bodies of the solar system. Aims: In November 2010 an experiment with a prototype of a laser frequency comb (LFC) calibration system was performed with the HARPS spectrograph of the 3.6m ESO telescope at La Silla during which high signal-to-noise spectra of the Moon were obtained. We exploit those Echelle spectra to study a portion of the optical integrated solar spectrum and in particular to determine the solar photospheric line positions. Methods: The DAOSPEC program is used to measure solar line positions through Gaussian fitting in an automatic way. The solar spectra are calibrated both with an LFC and a Th-Ar. Results: We first apply the LFC solar spectrum to characterize the CCDs of the HARPS spectrograph. The comparison of the LFC and Th-Ar calibrated spectra reveals S-type distortions on each order along the whole spectral range with an amplitude of ±40 m s-1 . This confirms the pattern found in the first LFC experiment on a single order and extends the detection of the distortions to the whole analyzed region revealing that the precise shape varies with wavelength. A new data reduction is implemented to deal with CCD pixel inequalities to obtain a wavelength corrected solar spectrum. By using this spectrum we provide a new LFC calibrated solar atlas with 400 line positions in the range of 476-530, and 175 lines in the 534-585 nm range corresponding to the LFC bandwidth. The new LFC atlas is consistent on average with that based on FTS solar spectra, but it improves the accuracy of individual lines by a significant factor reaching a mean value of ?10 m s-1 . Conclusions: The LFC-based solar line wavelengths are essentially free of major instrumental effects and provide a reference for absolute solar line positions at the date of Nov. 2010, i.e. an epoch of low solar activity. We suggest that future LFC observations could be used to trace small radial velocity changes of the whole solar photospheric spectrum in connection with the solar cycle and for direct comparison with the predicted line positions of 3D radiative hydrodynamical models of the solar photosphere. The LFC calibrated solar atlas can be also used to verify the accuracy of ground or space spectrographs by means of the solar spectrum. Observations based on the ESO 3.6 m telescope at La Silla, Chile.Full Table 3 and a solar spectrum are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A61

Molaro, P.; Esposito, M.; Monai, S.; Lo Curto, G.; González Hernández, J. I.; Hänsch, T. W.; Holzwarth, R.; Manescau, A.; Pasquini, L.; Probst, R. A.; Rebolo, R.; Steinmetz, T.; Udem, Th.; Wilken, T.

2013-12-01

151

Multiplexed Detection of CO2 Using a Novel Dual Comb Spectrometer  

NASA Astrophysics Data System (ADS)

We report multiheterodyne-detected cavity-enhanced absorption spectroscopy (MH-CEAS) of CO2 in the near-infrared using a novel frequency comb light source generated from the electro-optical modulation of a single continuous-wave laser. Using a pair of dual-drive Mach Zehnder modulators we create two frequency combs of slightly different comb mode spacing. The probe comb is coupled to a high-finesse optical cavity containing CO2 and then combined with the local oscillator comb on a photodetector. This results in down-conversion of the optical comb to radio frequencies, therefore facilitating fast, multiplexed analysis of the CO2 direct absorption signal. The noise-equivalent absorption coefficient for MH-CEAS as initially demonstrated here is 3×10-10 cm-1 Hz-1/2 per spectral element for ˜50 simultaneously resolved channels of unique optical frequency.

Fleisher, Adam J.; Long, David A.; Hodges, Joseph; Plusquellic, David F.

2014-06-01

152

Prostitution & Sex Trafficking  

E-print Network

Prostitution & Sex Trafficking in Spain BY: Brittany Rittenberry Political Science & International purchased sex There are 1.5 Million sex transactions everyday #12;Argument: Sex trafficking in Spain would/3 #12;What was concluded... Terminology Demand Supply Sex Trafficking Prostitution #12;#12;For more

New Hampshire, University of

153

Effects of Aromatase Inhibitor on Sex Differentiation and Levels of P450 17?and P450 aromMessenger Ribonucleic Acid of Gonads in Chicken Embryos  

Microsoft Academic Search

On Day 5 of incubation fertilized eggs of single-comb White Leghorn hens were injected with an aromatase inhibitor (AI) and the sex reversal effect and levels of mRNA of P45017?-hydroxylase(P45017?) and P450aromatase(P450arom) were evaluated by observation of gonadal phenotype and by Northern and slot blot analysis. Individual genetic sex was evaluated by Southern blot analysis of red blood cells using

K Abinawanto; Kiyoshi Shimada; Kumiko Yoshida; Noboru Saito

1996-01-01

154

Analysis of Force Interactions Between Comb Stabilized Colloidal Particles  

NASA Astrophysics Data System (ADS)

Polymer chains that are chemically attached to solid surfaces have important uses in colloidal stabilization. In this investigation, atomic force colloid probe microscopy and Langmuir trough compression have been employed to observe the interactions between colloidal particles stabilized by tethered polymer chains. Monodisperse latexes stabilized by hydrophilic side chains of surface- attached comb polymers are analyzed by the above methods in a water environment. Through the modification of the comb arcitecture to incorporate both hydrophilic and hydrophobic side chains, attractive wells are introduced into the force-distance profiles, in agreement with recent self-consistent mean field predictions. A theoretical model has been developed to explain the differing behaviors of the colloids when analyzed by the above methods.

Olugebefola, Solar; Banerjee, Pallab; Park, Stella; Mayes, Anne; Iyer, J.; Bembenek, Catherine; Hammond, Paula

2001-03-01

155

Precision Spectroscopy of Hydrogen and Femtosecond Laser Frequency Combs  

NASA Astrophysics Data System (ADS)

The simple hydrogen atom has inspired many advances in quantum electrodynamics and experimental techniques. As the latest spin off, femtosecond optical frequency comb synthesizers have revolutionized the way optical frequencies are measured, and provide a reliable clock mechanism for optical atomic clocks. Precision spectroscopy of the hydrogen 1S-2S two-photon resonance has reached an accuracy of 1.4 parts in 1014, and considerable future improvements are envisioned. Such laboratory experiments are setting new limits for possible slow variations of the electromagnetic and strong interaction. The frequency comb technique has recently been extended into the extreme ultraviolet and may allow similar measurements on hydrogen like ions that can be held in a trap.

Udem, Th.; Fendel, P.; Fischer, M.; Kolachevsky, N.; Alnis, J.; Zimmermann, M.; Gohle, Ch.; Herrmann, M.; Holzwarth, R.; Hänsch, T. W.

2005-12-01

156

Generation of a frequency comb and applications thereof  

DOEpatents

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.

Hagmann, Mark J; Yarotski, Dmitry A

2013-12-03

157

Comb-locked cavity ring-down spectrometer  

NASA Astrophysics Data System (ADS)

Extreme frequency accuracy and high sensitivity are obtained with a novel comb-locked cavity-ring-down spectrometer operating in the near-infrared from 1.5 to 1.63 ?m. A key feature of our approach is the tight frequency locking of the probe laser to the comb, ensuring very high reproducibility and accuracy to the frequency axis upon scanning the comb repetition rate, as well as an efficient light injection into a length-swept high-finesse passive cavity containing the gas sample. Spectroscopic tests on the (30012) ? (00001) P14e line of CO2 at ˜1.57 ?m demonstrate an accuracy of ˜17 kHz on the line center frequency in a Doppler broadening regime over the time scale of about 5 min, corresponding to four consecutive spectral scans of the absorption line. Over a single scan, which consists of 1500 spectral points over 75 s, the limit of detection is as low as 5.7 × 10-11 cm-1.

Gatti, Davide; Sala, Tommaso; Gotti, Riccardo; Cocola, Lorenzo; Poletto, Luca; Prevedelli, Marco; Laporta, Paolo; Marangoni, Marco

2015-02-01

158

Single DNA Condensation Induced by Hexammine Cobalt with Molecular Combing  

NASA Astrophysics Data System (ADS)

We investigated the interaction between DNA and hexammine cobalt III [Co(NH3)6]3+ by a simple molecular combing method and dynamic light scattering. The average extension of ?-DNA-YOYO-1 complex is found to be 20.9 ?m, about 30% longer than the contour length of the DNA in TE buffer (10 mmol/L Tris, 1 mmol/L EDTA, pH=8.0), due to bis-intercalation of YOYO-1. A multivalent cation, hexammine cobalt, is used for DNA condensation. We find that the length of DNA-[Co(NH3)6]3+ complexes decrease from 20.9 ? to 5.9 ? as the concentration of the [Co(NH3)6]3+ vary from 0 to 3 ?mol/L. This observation provides a direct visualization of single DNA condensation induced by hexammine cobalt. The results from the molecular combing studies are supported by dynamic light scattering investigation, where the average hydrodynamic radius of the DNA complex decreases from 203.8 nm to 39.26 nm under the same conditions. It shows that the molecular combing method is feasible for quantitative conformation characterization of single bio-macromolecules.

Hu, Gao-ming; Lin, Yu; Ran, Shi-yong; Wang, Yan-wei; Yang, Guang-can

2012-06-01

159

Comb-locked cavity ring-down spectrometer.  

PubMed

Extreme frequency accuracy and high sensitivity are obtained with a novel comb-locked cavity-ring-down spectrometer operating in the near-infrared from 1.5 to 1.63 ?m. A key feature of our approach is the tight frequency locking of the probe laser to the comb, ensuring very high reproducibility and accuracy to the frequency axis upon scanning the comb repetition rate, as well as an efficient light injection into a length-swept high-finesse passive cavity containing the gas sample. Spectroscopic tests on the (30012) ? (00001) P14e line of CO2 at ?1.57 ?m demonstrate an accuracy of ?17 kHz on the line center frequency in a Doppler broadening regime over the time scale of about 5 min, corresponding to four consecutive spectral scans of the absorption line. Over a single scan, which consists of 1500 spectral points over 75 s, the limit of detection is as low as 5.7 × 10(-11) cm(-1). PMID:25702008

Gatti, Davide; Sala, Tommaso; Gotti, Riccardo; Cocola, Lorenzo; Poletto, Luca; Prevedelli, Marco; Laporta, Paolo; Marangoni, Marco

2015-02-21

160

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

PubMed

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. PMID:23038314

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

2012-07-30

161

A preliminary investigation of the potential mechanical sensitivity of vertical comb drives  

NASA Astrophysics Data System (ADS)

This article describes a preliminary step taken in investigating the potential of vertical comb drives to be used as force-compensation mechanisms in interfacial force microscopes, by exploring the lower limit of the stiffness of the springs the comb drives can be fabricated with. The stiffness of their springs will affect the sensitivity of the microscope. Six vertical comb drives were fabricated for this study; the dimensions of their spring beams were chosen with the intention of giving them stiffnesses of three different orders of magnitude. During fabrication it was found that etching the tops of some of the teeth down to create the vertical offset between the combs can be done using only photoresist to mask the rest of the teeth. The stiffnesses of the fabricated springs were estimated by applying loads to them and measuring their resulting deflections. Weights were applied to the two comb drives with the stiffest springs. Voltages were also applied to them so as to determine the force-voltage relationship for their comb design. Since the other four comb drives had the same comb design, the stiffnesses of their springs could be estimated from the displacements of their movable combs when voltages were applied to them.

Gallagher, E.; Moussa, W.

2014-10-01

162

Additional sex combs-like family genes are required for normal cardiovascular development.  

PubMed

Congenital heart disease (CHD) is the most common birth defect. However, the majority of CHD cases have unknown etiology. Here we report the identification of ASXL2 and ASXL1, two homologous chromatin factors, as novel regulators of heart development. Asxl2(-/-) fetuses have reduced body weight and display congenital heart malformations including thickened compact myocardium in the left ventricle, membranous ventricular septal defect, and atrioventricular valval stenosis. Although most Asxl2(-/-) animals survive to term, the neonates have patent ductus arteriosus and consequent lung hemorrhage and die soon after birth. Asxl1(-/-) fetuses have reduced body weight and display cleft palate, anophthalmia as well as ventricular septal defects and a failure in lung maturation. From these results, we conclude that normal heart development requires both ASXL proteins. In particular, ASXL2 plays an important role in heart morphogenesis and the transition from fetal to postnatal circulation. PMID:24860998

McGinley, Andrea L; Li, Yanyang; Deliu, Zane; Wang, Q Tian

2014-07-01

163

The Tribolium castaneum ortholog of Sex combs reduced controls dorsal ridge development  

Technology Transfer Automated Retrieval System (TEKTRAN)

In insects, the boundary between the embryonic head and thorax is formed by the dorsal ridge, a fused structure composed of portions of the maxillary and labial segments. However, the mechanisms that promote development of this unusual structure remain a mystery. In Drosophila, mutations in the Hox ...

164

Sex and Arthritis  

MedlinePLUS

... Pain Pregnancy and Rheumatic Disease Sex and Arthritis Sex and Arthritis PRINT Download PDF Description Sexuality is ... sensation Erectile dysfunction or impotence Begin overcoming barriers Sex is not simply about reaching rapid orgasm with ...

165

Sex-linked dominant  

MedlinePLUS

Inheritance - sex-linked dominant; Genetics - sex-linked dominant; X-linked dominant; Y-linked dominant ... type of chromosome that is affected (autosomal or sex chromosome). It also depends on whether the trait ...

166

Electrostatic comb-drive actuator for MEMS relays/switches with double-tilt comb fingers and tilted parallelogram beams  

NASA Astrophysics Data System (ADS)

MEMS relays/switches have been some of the most interesting hotspots in all kinds of MEMS devices for decades. Electrostatic actuation is the most popular actuation principle. A novel in-plane electrostatic comb-drive actuator for MEMS relays/switches was designed and fabricated. Double-tilt comb fingers and tilted parallelogram beams were proposed to achieve the requirements of MEMS relays/switches. The restoring force curve, actuation force curve, and pull-in voltage were measured. Double-tilt fingers were found to have a larger actuation force than traditional rectangular fingers, and the pull-in voltage was decreased by 25% by replacing rectangular fingers with double-tilt fingers. In addition, tilted parallelogram beams provided a convex upward restoring force curve, which was more suitable for MEMS relays/switches than the conventional force curve.

Gao, Yongfeng; You, Zheng; Zhao, Jiahao

2015-04-01

167

Broadband Mid-Infrared Comb-Resolved Fourier Transform Spectroscopy  

NASA Astrophysics Data System (ADS)

We report on a comb-resolved, broadband, direct-comb spectroscopy system in the mid-IR and its application to the detection of trace gases and molecular line shape analysis. By coupling an optical parametric oscillator (OPO), a 100 m multipass cell, and a high-resolution Fourier transform spectrometer (FTS), sensitive, comb-resolved broadband spectroscopy of dilute gases is possible. The OPO has radiation output at 3.1-3.7 and 4.5-5.5 ?m. The laser repetition rate is scanned to arbitrary values with 1 Hz accuracy around 417 MHz. The comb-resolved spectrum is produced with an absolute frequency axis depending only on the RF reference (in this case a GPS disciplined oscillator), stable to 1 part in 10^9. The minimum detectable absorption is 1.6x10-6 wn Hz-1/2. The operating range of the experimental setup enables access to strong fundamental transitions of numerous molecular species for applications based on trace gas detection such as environmental monitoring, industrial gas calibration or medical application of human breath analysis. In addition to these capabilities, we show the application for careful line shape analysis of argon-broadened CO band spectra around 4.7 ?m. Fits of the obtained spectra clearly illustrate the discrepancy between the measured spectra and the Voigt profile (VP), indicating the need to include effects such as Dicke narrowing and the speed-dependence of the collisional width and shift in the line shape model, as was shown in previous cw-laser studies. In contrast to cw-laser based experiments, in this case the entire spectrum (˜ 250 wn) covering the whole P and R branches can be measured in 16 s with 417 MHz resolution, decreasing the acquisition time by orders of magnitude. The parallel acquisition allows collection of multiple lines simultaneously, removing the correlation of possible temperature and pressure drifts. While cw-systems are capable of measuring spectra with higher precision, this demonstration opens the door for fast, massively parallel line shape parameters retrieval combined with analysis reaching beyond the VP and with absolute frequency calibration delivered by frequency combs. R. Wehr et al. J. Mol. Spec. 235 54-68 (2003) A. Cygan, et al. Eur. Phys. J. Special Topics 222 2119-2142 (2013)

Lee, Kevin; Mills, Andrew; Mohr, Christian; Jiang, Jie; Fermann, Martin; Maslowski, Piotr

2014-06-01

168

Genomics of Sex and Sex Chromosomes  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sex chromosomes are distinctive, not only because of their gender determining role, but also for genomic features that reflect their evolutionary history. The genomic sequences in the ancient sex chromosomes of humans and in the incipient sex chromosomes of medaka, stickleback, and papaya exhibit u...

169

Physicochemical characterization of PEG-based comb-like amphiphilic copolymer structures for possible imaging and therapeutic applications  

E-print Network

Comb-like copolymer structures, also known as graft/comb copolymers, have obtained a significant amount of attention in biomedical and industrial applications because of their unique compositional flexibility, which can ...

Dawson, Jin Zhou

2008-01-01

170

A Lateral-Axis Microelectromechanical Tuning-Fork Gyroscope With Decoupled Comb Drive Operating at Atmospheric Pressure  

Microsoft Academic Search

In this paper, a silicon bulk micromachined lateral-axis tuning-fork gyroscope (TFG) with a decoupled comb drive and torsional sensing comb capacitors is presented. The novel driving comb capacitors are used to suppress the parasitic out-of-plane electrostatic force and, hence, can decouple the mechanical crosstalk from the sensing mode to the driving mode in a simple manner. The torsional sensing combs

Zhong Yang Guo; Long Tao Lin; Qian Cheng Zhao; Zhen Chuan Yang; Huikai Xie; Gui Zhen Yan

2010-01-01

171

The Riddle of Sex.  

ERIC Educational Resources Information Center

Discusses the work of evolutionary biologists in determining how sexual reproduction arose. Topics explored include the nature of sex, bacterial sex, meiotic sex, and asexual reproduction. A diagram (which can be used as a duplicating master) illustrating types of bacterial sex is included. (DH)

Sagan, Dorion; Margulis, Lynn

1985-01-01

172

Astronomical optical frequency comb generation and test in a fiber-fed MUSE spectrograph  

NASA Astrophysics Data System (ADS)

We here report on recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam and present preliminary test results using the fiber-fed Multi Unit Spectroscopic Explorer (MUSE) spectrograph. The frequency comb is generated by propagating two free-running lasers at 1554.3 and 1558.9 nm through two dispersionoptimized nonlinear fibers. The generated comb is centered at 1590 nm and comprises more than one hundred lines with an optical-signal-to-noise ratio larger than 30 dB. A nonlinear crystal is used to frequency double the whole comb spectrum, which is efficiently converted into the 800 nm spectral band. We evaluate first the wavelength stability using an optical spectrum analyzer with 0.02 nm resolution and wavelength grid of 0.01 nm. After confirming the stability within 0.01 nm, we compare the spectra of the astro-comb and the Ne and Hg calibration lamps: the astro-comb exhibits a much larger number of lines than lamp calibration sources. A series of preliminary tests using a fiber-fed MUSE spectrograph are subsequently carried out with the main goal of assessing the equidistancy of the comb lines. Using a P3d data reduction software we determine the centroid and the width of each comb line (for each of the 400 fibers feeding the spectrograph): equidistancy is confirmed with an absolute accuracy of 0.4 pm.

Chavez Boggio, J. M.; Fremberg, T.; Moralejo, B.; Rutowska, M.; Hernandez, E.; Zajnulina, M.; Kelz, A.; Bodenmüller, D.; Sandin, C.; Wysmolek, M.; Sayinc, H.; Neumann, J.; Haynes, R.; Roth, M. M.

2014-07-01

173

Occurrence of fungi in combs of fungus-growing termites (Isoptera: Termitidae, Macrotermitinae)  

Microsoft Academic Search

Fungus-growing termites cultivate their mutualistic basidiomycete Termitomyces species on a substrate called a fungal comb. Here, the Suicide Polymerase Endonuclease Restriction (SuPER) method was adapted for the first time to a fungal study to determine the entire fungal community of fungal combs and to test whether fungi other than the symbiotic cultivar interact with termite hosts. Our molecular analyses show

Herbert J. Guedegbe; Edouard Miambi; Anne Pando; Jocelyne Roman; Pascal Houngnandan; Corinne Rouland-Lefevre

2009-01-01

174

Threshold features of a Brillouin Stokes comb generated in a distributed fiber Raman amplifier  

Microsoft Academic Search

We study threshold features of a Brillouin-shifted Stokes comb generated in a distributed fiber Raman amplifier. When the input power of Brillouin pump is linearly increased in high Raman gain, the first Stokes wave grows exponentially at much lower threshold power and then experiences an appreciable power decrease in the vicinity of the Brillouin comb's threshold. This power reduction of

Kap-Dong Park; Hanyoung Ryu; Won-Kyu Lee; Seung Kwan Kim; Han Seb Moon; Ho-Suhng Suh

2003-01-01

175

THE COMBS OF HONEYBEES AS COMPOSITE MATERIALS H.R. HEPBURN S.P. KURSTJENS  

E-print Network

THE COMBS OF HONEYBEES AS COMPOSITE MATERIALS H.R. HEPBURN S.P. KURSTJENS Department of Physiology of the African honeybee, A. m. scutellata, in relation to maturation and temperature were measured. Combs ranged a structure with new properties that differ from its individual constituents. INTRODUCTION The honeybee nest

Paris-Sud XI, Université de

176

Phase-stabilized 167 MHz Repetition Frequency Carbon Nanotube Fiber Laser Frequency Comb  

E-print Network

Phase-stabilized 167 MHz Repetition Frequency Carbon Nanotube Fiber Laser Frequency Comb Jinkang@phys.ksu.edu Abstract: The frequency comb generated by a high repetition frequency erbium-doped fiber ring laser using.3930) Metrological instrumentation; (320.7090) Ultrafast lasers; (060.5295) Photonic crystal fibers 1. Introduction

Washburn, Brian

177

Generation of a 6602100 nm laser frequency comb based on an erbium fiber laser  

E-print Network

Generation of a 660­2100 nm laser frequency comb based on an erbium fiber laser Gabriel Ycas,1 present a multibranch laser frequency comb based upon a 250 MHz mode-locked erbium-doped fiber laser that spans more than 300 THz of bandwidth, from 660 nm to 2100 nm. Light from a mode-locked Er:fiber laser

178

Multiwavelength generation in an erbium-doped fiber laser using in-fiber comb filters  

Microsoft Academic Search

Simultaneous continuous wave multiwavelength operation of an erbium-doped fiber laser has been demonstrated using two types of recently developed in-fiber grating comb filters. The lasing wavelengths and linewidths were determined by the comb filter, which was inserted in a ring cavity with a single inhomogeneously broadened gain medium.

Jong Chow; Graham Town; Ben Eggleton; Morten Ibsen; Kate Sugden; Ian Bennion

1996-01-01

179

Viscoelastic and dielectric studies on comb-and brush-shaped poly(n-butyl acrylate)  

E-print Network

Viscoelastic and dielectric studies on comb- and brush-shaped poly(n-butyl acrylate) Guy C. Berry a-butyl acrylate to give comb-shaped polymers, using ATRP methods in either case. The viscoelastic data reported in the prior work, J0(u) and J00(u) may be represented by the expressions from linear viscoelasticity [5,6]: J0

Kurnikova, Maria

180

Optimally Coherent Kerr Combs Generated with Crystalline Whispering Gallery Mode Resonators for Ultrahigh Capacity Fiber Communications  

NASA Astrophysics Data System (ADS)

Optical Kerr frequency combs are known to be effective coherent multiwavelength sources for ultrahigh capacity fiber communications. These combs are the frequency-domain counterparts of a wide variety of spatiotemporal dissipative structures, such as cavity solitons, chaos, or Turing patterns (rolls). In this Letter, we demonstrate that Turing patterns, which correspond to the so-called primary combs in the spectral domain, are optimally coherent in the sense that for the same pump power they provide the most robust carriers for coherent data transmission in fiber communications using advanced modulation formats. Our model is based on a stochastic Lugiato-Lefever equation which accounts for laser pump frequency jitter and amplified spontaneous emission noise induced by the erbium-doped fiber amplifier. Using crystalline whispering-gallery-mode resonators with quality factor Q ˜109 for the comb generation, we show that when the noise is accounted for, the coherence of a primary comb is significantly higher than the coherence of their solitonic or chaotic counterparts for the same pump power. In order to confirm this theoretical finding, we perform an optical fiber transmission experiment using advanced modulation formats, and we show that the coherence of the primary comb is high enough to enable data transmission of up to 144 Gbit /s per comb line, the highest value achieved with a Kerr comb so far. This performance evidences that compact crystalline photonic systems have the potential to play a key role in a new generation of coherent fiber communication networks, alongside fully integrated systems.

Pfeifle, Joerg; Coillet, Aurélien; Henriet, Rémi; Saleh, Khaldoun; Schindler, Philipp; Weimann, Claudius; Freude, Wolfgang; Balakireva, Irina V.; Larger, Laurent; Koos, Christian; Chembo, Yanne K.

2015-03-01

181

Evaluation of an adaptive comb filtering method for enhancing speech degraded by white noise addition  

Microsoft Academic Search

An intelligibility test was performed to evaluate an adaptive comb filtering method proposed by Frazier [2] for enhancement of degraded speech due to additive white noise. Results indicate that independent of S\\/N ratio the adaptive comb filtering scheme does not increase speech intelligibility.

Jae Lim; A. Oppenheim; L. Braida

1978-01-01

182

Optical properties of the iridescent organ of the comb-jellyfish Beroë cucumis (Ctenophora)  

Microsoft Academic Search

Using transmission electron microscopy, analytical modeling, and detailed numerical simulations, the iridescence observed from the comb rows of the ctenophore Beroë cucumis was investigated. It is shown that the changing coloration which accompanies the beating of comb rows as the animal swims can be explained by the weakly-contrasted structure of the refractive index induced by the very coherent packing of

Victoria Welch; Jean Pol Vigneron; Virginie Lousse; Andrew Parker

2006-01-01

183

Fourier transform spectroscopy around 3 microns with a broad difference frequency comb  

E-print Network

We characterize a new mid-infrared frequency comb generator based on difference frequency generation around 3.2 microns. High power per comb mode (>10-7 W/mode) is obtained over a broad spectral span (>700 nm). The source is used for direct absorption spectroscopy with a Michelson-based Fourier transform interferometer.

Meek, Samuel A; Guelachvili, Guy; Hänsch, Theodor W; Picqué, Nathalie

2013-01-01

184

White-light frequency comb generation with a diode-pumped CrLiSAF laser  

Microsoft Academic Search

Received January 3, 2001 We have created a broad spectrum spanning more than an optical octave by launching femtosecond pulses from a battery operated Cr:LiSAF laser into a photonic crystal fiber. Despite the massive broadening in the fiber, the comb structure of the spectrum is preserved, and this frequency comb is perfectly suited for applications in optical frequency metrology. ?

R. Holzwarth; M. Zimmermann; Th. Udem; T. W. Hänsch; P. Russbüldt; K. Gäbel; R. Poprawe; J. C. Knight; W. J. Wadsworth; P. St. J. Russell

2001-01-01

185

Complete characterization of a broadband high-finesse cavity using an optical frequency comb  

Microsoft Academic Search

We demonstrate a new method to simultaneously measure spectrally resolved dispersion and losses (finesse) of a passive optical cavity over the entire bandwidth of an optical frequency comb. To this end, we record and analyze the spectral Moiré pattern between the perfectly equidistant frequency comb emitted from a Ti:Sapphire laser and the longitudinal modes of the passive cavity as a

Albert Schliesser; Christoph Gohle; Thomas Udem; Theodor W. Hänsch

2006-01-01

186

Phase-stabilized Prism-based Cr:forsterite Laser Frequency Comb for Absolute Frequency Measurements  

E-print Network

Phase-stabilized Prism-based Cr:forsterite Laser Frequency Comb for Absolute Frequency Measurements., Somerset NJ 08873 Abstract: A prism-based Cr:forsterite frequency comb is stabilized, with a repetition rate of 116 MHz. The flexibility of the prism-based system aids in achieving the carrier

Washburn, Brian

187

A flat and broadband optical frequency comb with tunable bandwidth and frequency spacing  

NASA Astrophysics Data System (ADS)

A flat and broadband optical frequency comb generator based on two cascaded intensity modulators is proposed and experimentally demonstrated. In this scheme, we first use even or odd harmonic sidebands to generate optical frequency comb, so the bandwidth can be improved. By adjusting the power of the microwave signals and the direct current bias applied to the modulators, a flat and broadband optical frequency comb can be achieved. The scheme is relatively simple and adjustable, where the frequencies spacing vary with microwave frequency applied on modulators. 15 and 20 comb lines with the comb flatness within 1 dB can be generated. The generated spectrums can meet the requirement of OFDM modulation, and can be used for high capacity optical transmission systems in the future.

Shang, Lei; Wen, Aijun; Lin, Guibin; Gao, Yongsheng

2014-11-01

188

Tunable silicon Fabry-Perot comb filters formed by Sagnac loop mirrors.  

PubMed

We experimentally demonstrate tunable silicon comb filters based on Fabry-Perot (FP) resonators composed of two Sagnac loop mirrors. The comb filter resolves up to 54 comb lines with a 115 GHz channel spacing over a spectral range from 1510 to 1560 nm. The comb line extinction ratio is ~26.3 dB and the quality factor is ~57,000 around 1550 nm wavelength. Electrical tuning is enabled via periodically interleaved PN junctions embedded inside the FP resonator. The comb lines are blue shifted by ~0.92 nm (one channel spacing) with a 5 mA forward-bias current and red-shifted by ~0.05 nm with a -10 V reverse-bias voltage. PMID:23455138

Sun, Xiaomeng; Zhou, Linjie; Xie, Jingya; Zou, Zhi; Lu, Liangjun; Zhu, Haike; Li, Xinwan; Chen, Jianping

2013-02-15

189

Whispering gallery mode sensing with a dual frequency comb probe.  

PubMed

Silica microspheres are probed with a dual comb interferometry setup. The impulse responses of these microresonators are measured with a temporal resolution smaller than 400 fs over more than 200 ps. The amplitudes and phases of the impulse responses are interpreted as providing sensing information. The more familiar transmission spectra corresponding to the measured impulse responses are also calculated and shown. Sensing is demonstrated by varying the concentration of isopropanol in de-ionized water surrounding the microsphere and by binding bovine serum albumin on the silanized microsphere surface. PMID:22330543

Michaud-Belleau, Vincent; Roy, Julien; Potvin, Simon; Carrier, Jean-Raphaël; Verret, Louis-Simon; Charlebois, Maxime; Genest, Jérôme; Nì Allen, Claudine

2012-01-30

190

Parametric seeding of a microresonator optical frequency comb.  

PubMed

We have investigated parametric seeding of a microresonator frequency comb (microcomb) by way of a pump laser with two electro-optic-modulation sidebands. We show that the pump-sideband spacing is precisely replicated throughout the microcomb's optical spectrum, and we demonstrate a record absolute line-spacing stability for microcombs of 1.6 × 10(-13) at 1 s. The spectrum of a microcomb is complex, and often non-equidistant subcombs are observed. Our results demonstrate that parametric seeding can not only control the subcombs, but can lead to the generation of a strictly equidistant microcomb spectrum. PMID:23938634

Papp, Scott B; Del'Haye, Pascal; Diddams, Scott A

2013-07-29

191

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

PubMed Central

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. PMID:25350504

Gallagher, Else; Moussa, Walied

2014-01-01

192

A study of the effect of the fringe fields on the electrostatic force in vertical comb drives.  

PubMed

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. PMID:25350504

Gallagher, Else; Moussa, Walied

2014-01-01

193

The viscoelasticity of self-assembled proteoglycan combs.  

PubMed

Particle tracking microrheology with a fast digital camera allowed the slow and intermediate time regimes (10(-4)-10(1) s) of the linear viscoelasticity of giant aggrecan proteoglycans to be mapped. Combined with diffusing wave spectroscopy experiments this enabled us to probe the linear viscoelasticity of aggrecan over seven orders of magnitude in time (10(-6)-10(1) s) [Palmer et al., Biophys. J., 1999, 76, 1063; Papagiannopoulos et al., Biomacromolecules, 2007, 7, 2162]. When the comb side-groups self-assemble on the hyaluronic acid backbones they cause a dramatic increase in the relaxation time of the solutions and consequently the viscosity of the sample, but leave the elasticity of the solutions relatively unchanged. The experiments illustrate the modular nature of aggrecan's viscosity and clearly demonstrate the role of this molecule in vivo in cartilaginous composites, where it dissipates energy. Both one- and two-particle tracking microrheology were used to investigate the length-scale dependent viscoelasticity of the comb superstructures [Lui et al., Phys. Rev. Lett., 2006, 96, 118104] and the errors inherent in the two techniques were quantified [Savin and Doyle, Biophys. J., 2005, 88, 623; Waigh, Rep. Prog. Phys., 2005, 68, 685]. The behaviour of the viscoelasticity is compared with the predictions of dynamic scaling theory, indicating a significant contribution of the side-chain dynamics to the reptative motion of both the aggrecan aggregate and the monomers. The results have important implications for a molecular understanding of tissue function and pathology in osteoarthritis. PMID:19049005

Papagiannopoulos, A; Waigh, T A; Hardingham, T E

2008-01-01

194

Evaluation of distributed-type inorganic electroluminescence devices using comb-shaped electrodes  

NASA Astrophysics Data System (ADS)

We deposited comb-shaped metal electrodes with narrow gaps on a glass substrate and succeeded in achieving a high electric field intensity. Using conventional structures, this result could only be achieved by applying transparent electrodes, and in this study, we used a comb-shaped metal (Au) electrode and a comb-shaped indium tin oxide (ITO) electrode. When we measured the luminescence from the opposite side of the comb-shaped electrodes, at 15 V/µm, the luminance in the ITO electrode sample was identical (92–95 cd/m2) to that measured from the side of the comb-shaped electrodes. Conversely, a 111-cd/m2 brightness (a 1.9-fold increase) was observed from the opposite side of the Au electrode. Electrode transmittance was unnecessary when the luminescence was observed from the opposite side of the comb-shaped electrodes, and by using metals such as Au, it was possible to produce a display that did not require transparent electrodes. Finally, we simulated the electric field distribution for the inorganic electroluminescence (EL) using comb-shaped electrodes by semiconductor device simulator Atlas.

Nonaka, Toshihiro; Uraoka, Yukiharu; Taguchi, Nobuyoshi; Yamamoto, Shin-ichi

2015-03-01

195

Comb construction in mixed-species colonies of honeybees, Apis cerana and Apis mellifera.  

PubMed

Comb building in mixed-species colonies of Apis cerana and Apis mellifera was studied. Two types of cell-size foundation were made from the waxes of these species and inserted into mixed colonies headed either by an A. cerana or an A. mellifera queen. The colonies did not discriminate between the waxes but the A. cerana cell-size foundation was modified during comb building by the workers of both species. In pure A. cerana colonies workers did not accept any foundation but secreted wax and built on foundation in mixed colonies. Comb building is performed by small groups of workers through a mechanism of self-organisation. The two species cooperate in comb building and construct nearly normal combs but they contain many irregular cells. In pure A. mellifera colonies, the A. cerana cell size was modified and the queens were reluctant to lay eggs on such combs. In pure A. cerana colonies, the A. mellifera cell size was built without any modification but these cells were used either for drone brood rearing or for food storing. The principal elements of comb-building behaviour are common to both species, which indicates that they evolved prior to and were conserved after speciation. PMID:20435816

Yang, Ming-Xian; Tan, Ken; Radloff, Sarah E; Phiancharoen, Mananya; Hepburn, H Randall

2010-05-01

196

The Development and Implementation of Chirped-Pulse Frequency Combs at Millimeter Wavelengths  

NASA Astrophysics Data System (ADS)

Technological advances in such areas as active multiplier chains and high-speed digital electronics are enabling the development of sensitive high-throughput spectroscopic instruments in the millimeter and submillimeter ranges. Recently there has been an effort to develop multiplexed direct absorption spectroscopy techniques that use frequency comb sources derived from phase-locked pulse trains (often created using ultrafast lasers). We have used a high-speed arbitrary waveform generator (AWG with 12 GHz sample rate) to create frequency combs at mm-wave wavelengths using a chirped pulse as the repeating waveform. This waveform has important advantages including 100% duty cycle for the light output and compatibility with the use of frequency multiplier chains that extend the bandwidth of the comb proportional to the frequency multiplication factor. A new spectrometer operating in the 260-290 GHz range using active multiplier chains has been constructed to test the capabilities of chirped-pulse frequency comb spectroscopy for molecular rotational spectroscopy. The spectral properties of the mm-wave combs generated following x24 frequency multiplication, methods for compressed bandwidth detection using a dual-comb approach, and frequency comb analogs of FM spectroscopy will be presented.

Steber, Amanda L.; Harris, Brent J.; Neill, Justin L.; Lehmann, Kevin K.; Pate, Brooks H.

2012-06-01

197

Modeling Kerr frequency combs using the Lugiato-Lefever equation: a characterization of the multistable landscape  

NASA Astrophysics Data System (ADS)

Optical frequency combs can be used to measure light frequencies and time intervals more easily and precisely than ever before, opening a large avenue for applications. Traditional frequency combs are usually associated with trains of evenly spaced, very short pulses. More recently, a new generation of comb sources has been demonstrated in compact high-Q optical microresonators with a Kerr nonlinearity pumped by continuous-wave laser light. These combs are now referred to as Kerr frequency combs and have attracted a lot of interest in the last few years. Kerr frequency combs can be modeled in a way that is strongly reminiscent of temporal cavity solitons (CSs) in nonlinear cavities. Temporal CSs have been experimentally studied in fiber resonators and their description is based on a now classical equation, the Lugiato-Lefever equation, that describes pattern formation in optical systems. In this work, we first perform a theoretical study of the correspondence between the CSs and patterns with frequency combs. It is known that the CSs appear in reversible systems that present bistability between a pattern and a homogeneous steady state through what it is called a homoclinic snaking structure. In this snaking region, single and multi-peak CSs coexist with patterns and homogeneous solutions, creating a largely multistable landscape. We study the changes of the homoclinic snaking for different parameter regimes in the Lugiato-Lefever equation and determine the stability and shape of the frequency combs through comparison with the underlying CSs and patterns. Secondly, we include third order dispersion in the system and study its effect on the multistable snaking structure. For high dispersion strengths the CS structures and the corresponding Kerr frequency combs disappear.

Parra-Rivas, P.; Gomila, D.; Matias, M. A.; Leo, F.; Coen, S.; Gelens, L.

2014-05-01

198

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

NASA Astrophysics Data System (ADS)

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.

Mougeot, Francois

2008-02-01

199

Sex Education: Another View  

ERIC Educational Resources Information Center

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)

Hamilton, Jennifer

1977-01-01

200

Practice Safer Sex  

MedlinePLUS

... This information in Spanish ( en español ) Practice safer sex Related information Men's health Screening tests and vaccines ... Return to top More information on Practice safer sex Explore other publications and websites Addressing HIV, Other ...

201

Sex-Offender Tracking  

MedlinePLUS

... Safety & Prevention Law Enforcement Training Victim & Family Support Sex Offender Tracking The primary goal of the National Center for Missing & Exploited Children ® ’s Sex Offender Tracking Team ® (SOTT) is to provide assistance ...

202

Sex Differences in Obesity  

MedlinePLUS

Fact Sheet: Sex Differences in Obesity Part 1: Definitions and Epidemiology Part 2: Effects of Life Stages and Metabolic Hormones Part ... ethnic divide exists for overall obesity and for sex differences in obesity. Among black people, 54.3% ...

203

Microphase separation of comb copolymers with two different lengths of side chains  

NASA Astrophysics Data System (ADS)

The phase behavior of the monodisperse AB comb copolymer melt contained the macromolecules of special architecture is discussed. Each macromolecule is assumed to be composed of two comb blocks which differ in numbers of side chains and numbers of monomer units in these chains. It is shown (by analysis of the structure factor of the melt) that microphase separation at two different length scales in the melt is possible. The large and small length scales correspond to separation between comb blocks and separation between monomer units in repeating fragments of blocks, respectively. The classification diagrams indicated which length scale is favored for a given parameters of chemical structure of macromolecules are constructed.

Aliev, M. A.; Kuzminyh, N. Yu.

2009-10-01

204

Effects of sex and sex roles on avoidance of same- and opposite-sex touch.  

PubMed

Touch and touch avoidance are important facets of interpersonal relations. Touch avoidance has been related to sex, but the relationship between touch and sex roles has not been widely substantiated. 259 undergraduate students participated in a procedure designed to test the relationship between sex, sex roles, and same-sex and opposite-sex touch avoidance. Significant differences were reported between men and women on same-sex touch avoidance but not on opposite-sex touch avoidance. Participants high on androgyny reported less same-sex and opposite-sex touch avoidance than did subjects low on androgyny. No interactive effect between sex and androgyny was found for either same-sex or opposite-sex touch avoidance. Regression procedures indicated predictive models for sex and androgyny in relation to same-sex and opposite-sex touch avoidance. Specific conclusions regarding the relationships among sex, androgyny, and touch avoidance were stated. PMID:7991300

Crawford, C B

1994-08-01

205

Sex Differences in Stroke  

Microsoft Academic Search

Increasing evidence suggests that sex differences exist in the etiology, presentation, treatment, and outcome from stroke. The reasons for these sex disparities are becoming increasingly explored, but large gaps still exist in our knowledge. Experimental studies over the past several years have demonstrated intrinsic sex differences both in vivo and in animal models which may have relevance to our understanding

L. Christine Turtzo; Louise D. McCullough

2008-01-01

206

Single-Sex Classrooms  

ERIC Educational Resources Information Center

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

Protheroe, Nancy

2009-01-01

207

When Sex Is Painful  

MedlinePLUS

How common is painful sex? Pain during intercourse is very common—nearly 3 out of 4 women have pain during intercourse at some time during ... a long-term problem. What causes pain during sex? Pain during sex may be a sign of ...

208

Changing Sex Roles.  

ERIC Educational Resources Information Center

This article reviews literature on sex role change in children and points to areas which need further research. Competing ideologies which support or reject sex typing of role behaviors are briefly discussed in the introduction. The sources of sex role change are divided into two categories: (1) planned direct intervention programs and (2) natural…

Worell, Judith

209

The shapes of simple three and four junction comb polymers  

NASA Astrophysics Data System (ADS)

A scheme originally proposed by G. Wei [Physica A 222, 152 (1995); Physica A 222, 155 (1995)] is redesigned to produce numerical shape parameters of arbitrary tree-branched polymers based on the Kirchhoff matrix eigenvalue spectrum. This method and two different Monte Carlo techniques (pivot and growth) are employed to investigate the asphericity of three and four junction comb polymers in both the ideal and excluded volume regimes. It is found that the extrapolated g-ratio and asphericity values obtained by all of these methods are in excellent agreement with each other and the available theory in the ideal regime and that polymers with a complete set of interior branches display a more sphere-like shape.

von Ferber, Christian; Bishop, Marvin; Forzaglia, Thomas; Reid, Cooper; Zajac, Gregory

2015-01-01

210

Acoustic frequency combs for carrier-envelope phase stabilization.  

PubMed

A method for improved performance of feed-forward carrier-envelope phase stabilization in amplified laser sources is presented and experimentally demonstrated. The phase stabilization scheme is applicable for a broad range of repetition rates spanning from subhertz to 100 kHz. The method relies on driving an acousto-optic frequency shifter by few-cycle transients. The phase of these transients suitably controls the grating phase of the generated index grating inside the shifter material. This approach removes beam pointing as well as amplitude noise issues observed in continuously driven feed-forward schemes. The synthesis of these gratings can be understood as the acoustic equivalent of mode-locking or acoustic frequency combs. PMID:24487861

Borchers, Bastian; Lücking, Fabian; Steinmeyer, Günter

2014-02-01

211

High performance tunnel injection quantum dot comb laser  

SciTech Connect

A high-speed multiwavelength quantum dot comb laser, grown by molecular beam epitaxy, is demonstrated. The device is characterized with a 75.9 nm (full width at half maximum) and a 91.4 nm (DELTA{sub -15dB}) wide lasing spectrum. There are 105 and 185 simultaneously emitted longitudinal modes with a maximum channel intensity nonuniformity of less than 3 dB in the spectral range of 1231-1252 nm and 1274-1311 nm, respectively, for a laser with 1040 mum cavity length. The channel spacing can be tuned with cavity length and remains invariant in the temperature range of 300-323 K. The small signal modulation bandwidth is 7.5 GHz.

Lee, C.-S.; Guo Wei; Basu, Debashish; Bhattacharya, Pallab [Department of Electrical Engineering and Computer Science, Solid State Electronics Laboratory, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States)

2010-03-08

212

Time-Delay Interferometry with optical frequency comb  

E-print Network

Heterodyne laser phase measurements in a space-based gravitational wave interferometer are degraded by the phase fluctuations of the onboard clocks, resulting in unacceptable sensitivity performance levels of the interferometric data. In order to calibrate out the clock phase noises it has been previously suggested that additional inter-spacecraft phase measurements must be performed by modulating the laser beams. This technique, however, considerably increases system complexity and probability of subsystem failure. With the advent of self-referenced optical frequency combs, it is possible to generate the heterodyne microwave signal that is coherently referenced to the onboard laser. We show in this case that the microwave noise can be cancelled directly by applying modified second-generation Time-Delay Interferometric combinations to the heterodyne phase measurements. This approach avoids use of modulated laser beams as well as the need of additional ultra-stable oscillator clocks.

Massimo Tinto; Nan Yu

2015-02-23

213

Time-Delay Interferometry with optical frequency comb  

E-print Network

Heterodyne laser phase measurements in a space-based gravitational wave interferometer are degraded by the phase fluctuations of the onboard clocks, resulting in unacceptable sensitivity performance levels of the interferometric data. In order to calibrate out the clock phase noises it has been previously suggested that additional inter-spacecraft phase measurements must be performed by modulating the laser beams. This technique, however, considerably increases system complexity and probability of subsystem failure. With the advent of self-referenced optical frequency combs, it is possible to generate the heterodyne microwave signal that is coherently referenced to the onboard laser. We show in this case that the microwave noise can be cancelled directly by applying modified second-generation Time-Delay Interferometric combinations to the heterodyne phase measurements. This approach avoids use of modulated laser beams as well as the need of additional ultra-stable oscillator clocks.

Tinto, Massimo

2015-01-01

214

Coherent Raman spectro-imaging with laser frequency combs  

E-print Network

Optical spectroscopy and imaging of microscopic samples have opened up a wide range of applications throughout the physical, chemical, and biological sciences. High chemical specificity may be achieved by directly interrogating the fundamental or low-lying vibrational energy levels of the compound molecules. Amongst the available prevailing label-free techniques, coherent Raman scattering has the distinguishing features of high spatial resolution down to 200 nm and three-dimensional sectioning. However, combining fast imaging speed and identification of multiple - and possibly unexpected- compounds remains challenging: existing high spectral resolution schemes require long measurement times to achieve broad spectral spans. Here we overcome this difficulty and introduce a novel concept of coherent anti-Stokes Raman scattering (CARS) spectro-imaging with two laser frequency combs. We illustrate the power of our technique with high resolution (4 cm-1) Raman spectra spanning more than 1200 cm-1 recorded within le...

Ideguchi, Takuro; Bernhardt, Birgitta; Guelachvili, Guy; Picqué, Nathalie; Hänsch, Theodor W

2013-01-01

215

Neuroprotection of Sex Steroids  

PubMed Central

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

Liu, Mingyue; Kelley, Melissa H.; Herson, Paco S.; Hurn, Patricia D.

2011-01-01

216

Comb-calibrated solar spectroscopy through a multiplexed single-mode fiber channel  

E-print Network

We investigate a new scheme for astronomical spectrograph calibration using the laser frequency comb at the Solar Vacuum Tower Telescope on Tenerife. Our concept is based upon a single-mode fiber channel, that simultaneously feeds the spectrograph with comb light and sunlight. This yields nearly perfect spatial mode matching between the two sources. In combination with the absolute calibration provided by the frequency comb, this method enables extremely robust and accurate spectroscopic measurements. The performance of this scheme is compared to a sequence of alternating comb and sunlight, and to absorption lines from Earth's atmosphere. We also show how the method can be used for radial-velocity detection by measuring the well-explored 5-minute oscillations averaged over the full solar disk. Our method is currently restricted to solar spectroscopy, but with further evolving fiber-injection techniques it could become an option even for faint astronomical targets.

Probst, R A; Doerr, H-P; Steinmetz, T; Kentischer, T J; Zhao, G; Hänsch, T W; Udem, Th; Holzwarth, R; Schmidt, W

2015-01-01

217

An octave-spanning mid-infrared frequency comb generated in a silicon nanophotonic wire waveguide.  

PubMed

Laser frequency combs, sources with a spectrum consisting of hundred thousands evenly spaced narrow lines, have an exhilarating potential for new approaches to molecular spectroscopy and sensing in the mid-infrared region. The generation of such broadband coherent sources is presently under active exploration. Technical challenges have slowed down such developments. Identifying a versatile highly nonlinear medium for significantly broadening a mid-infrared comb spectrum remains challenging. Here we take a different approach to spectral broadening of mid-infrared frequency combs and investigate CMOS-compatible highly nonlinear dispersion-engineered silicon nanophotonic waveguides on a silicon-on-insulator chip. We record octave-spanning (1,500-3,300?nm) spectra with a coupled input pulse energy as low as 16?pJ. We demonstrate phase-coherent comb spectra broadened on a room-temperature-operating CMOS-compatible chip. PMID:25697764

Kuyken, Bart; Ideguchi, Takuro; Holzner, Simon; Yan, Ming; Hänsch, Theodor W; Van Campenhout, Joris; Verheyen, Peter; Coen, Stéphane; Leo, Francois; Baets, Roel; Roelkens, Gunther; Picqué, Nathalie

2015-01-01

218

Characterizing a fiber-based frequency comb with electro-optic modulator.  

PubMed

We report on the characterization of a commercial- core fiber-based frequency comb equipped with an intracavity free-space electro-optic modulator (EOM). We investigate the relationship between the noise of the pump diode and the laser relative intensity noise (RIN) and demonstrate the use of a low-noise current supply to substantially reduce the laser RIN. By measuring several critical transfer functions, we evaluate the potential of the EOM for comb repetition rate stabilization. We also evaluate the coupling to other relevant parameters of the comb. From these measurements, we infer the capabilities of the femtosecond laser comb to generate very-low-phase-noise microwave signals when phase-locked to a high-spectral-purity ultra-stable laser. PMID:22481776

Zhang, Wei; Lours, Michel; Fischer, Marc; Holzwarth, Ronald; Santarelli, Giorgio; Coq, Yann

2012-03-01

219

Characteristics of distributed-type inorganic electroluminescence panels with comb-shaped electrodes  

NASA Astrophysics Data System (ADS)

We deposited comb electrodes with narrow gaps between the teeth on a glass substrate, thus realizing a high electric field intensity that cannot be achieved with conventional structures. Au electrodes are deposited to form a comb shape and then spin-coated with a phosphor layer obtained by mixing ZnS phosphor particles with resins in a certain ratio. An AC voltage was applied to the gaps between the teeth of the comb electrode to emit light, from which the luminance was measured for different electric field intensities. The luminance was not affected by the transmittance of the electrodes themselves when measured from the phosphor layer side. Therefore, it may be possible to produce a display that does not require transparent electrodes by using the phosphor layer side of a device with comb electrodes made of metals, such as Au, for the display.

Yamamoto, Shin-Ichi; Uraoka, Yukiharu; Taguchi, Nobuyoshi; Nonaka, Toshihiro

2013-09-01

220

Tracing part-per-billion line shifts with direct-frequency-comb Vernier spectroscopy  

NASA Astrophysics Data System (ADS)

Accurate frequency measurements of molecular transitions around 2 ? m are performed by using a direct-frequency-comb spectroscopy approach that combines an Er+ frequency-comb oscillator at 1.5 ? m , a Tm-Ho fiber amplifier, and a Fabry-Perot-filter, high-resolution dispersive spectrometer optical multiplex-detection system. This apparatus has unique performances in terms of a wide dynamic range to integrate the intensity per comb mode, which allows one to measure molecular absorption profiles with high precision. Spectroscopic information about transition frequencies and linewidths is very accurately determined. Relative frequency uncertainties of the order of a few parts in 10-9 are achieved for rovibrational transitions of the CO2 molecule around 5100 cm-1. Moreover, tiny frequency shifts due to molecular collisions and interacting laser power using direct comb spectroscopy are investigated in a systematic way.

Siciliani de Cumis, M.; Eramo, R.; Coluccelli, N.; Cassinerio, M.; Galzerano, G.; Laporta, P.; De Natale, P.; Cancio Pastor, P.

2015-01-01

221

An octave-spanning mid-infrared frequency comb generated in a silicon nanophotonic wire waveguide  

NASA Astrophysics Data System (ADS)

Laser frequency combs, sources with a spectrum consisting of hundred thousands evenly spaced narrow lines, have an exhilarating potential for new approaches to molecular spectroscopy and sensing in the mid-infrared region. The generation of such broadband coherent sources is presently under active exploration. Technical challenges have slowed down such developments. Identifying a versatile highly nonlinear medium for significantly broadening a mid-infrared comb spectrum remains challenging. Here we take a different approach to spectral broadening of mid-infrared frequency combs and investigate CMOS-compatible highly nonlinear dispersion-engineered silicon nanophotonic waveguides on a silicon-on-insulator chip. We record octave-spanning (1,500–3,300?nm) spectra with a coupled input pulse energy as low as 16?pJ. We demonstrate phase-coherent comb spectra broadened on a room-temperature-operating CMOS-compatible chip.

Kuyken, Bart; Ideguchi, Takuro; Holzner, Simon; Yan, Ming; Hänsch, Theodor W.; van Campenhout, Joris; Verheyen, Peter; Coen, Stéphane; Leo, Francois; Baets, Roel; Roelkens, Gunther; Picqué, Nathalie

2015-02-01

222

Damping effects of capacitive comb fingers on biomimetic MEMS directional microphone  

NASA Astrophysics Data System (ADS)

MEMS directional sound sensors that use two coupled wings moving in air are subjected to viscous damping. The amplitude of oscillation of the sensors is read out by measuring the capacitance of interdigitated comb fingers along the edges of the wings. In this presentation, effects of damping on MEMS sensors with and without comb fingers will be described. It was found that the sensors with comb fingers have a significantly larger damping indicating that the longer perimeter due to combs is responsible for the observed increase [1]. However, the increase in damping reduces the quality factor which improves the response time of the device. [4pt] [1] W. Zhang and K. Turner, Sensors & Actuators: A. 134 p.594 (2007).

Roth, John; Touse, Michael; Sinibaldi, Jose; Karunasiri, Gamani

2011-03-01

223

Measuring the shift of a femtosecond laser frequency comb by the interference method  

Microsoft Academic Search

We have demonstrated the possibility of measuring the femtosecond laser frequency comb shift by the position of a Fabry — Perot interferometer's transmission bands with a statistical error of 10-2 and a systematic shift of 10-1.

Dmitriy V Basnak; K A Bikmukhametov; Aleksandr K Dmitriev; Aleksandr S Dychkov; Sergei A Kuznetsov; A A Lugovoy; P Mitsziti

2012-01-01

224

Quest for MeV frequency combs -- proposal for ELI experiments  

E-print Network

The optical frequency comb has become an indispensable tool for high precision spectroscopy. Also experiments in the field of ultrafast physics rely on the frequency comb technique to generate precisely controlled attosecond optical pulses by means of the high-order harmonic generation. However, in order to generate even shorter laser pulses or to apply this technique in investigations of nuclear structure, combs of frequencies of the order of MeV are necessary. It seems that it may not be possible to achieve such photon energies by high-order harmonic generation. In this context the possibility of the generation of Thomson and Compton-based frequency combs is presented. Diffraction of generated radiation by a sequence of laser pulses and its analogy to the diffraction grating is elucidated. Theoretical investigations presented in this report can be considered as the proposal for future ELI experiments [www.eli-laser.eu

Katarzyna Krajewska; Jerzy Z. Kami?ski

2014-10-04

225

Redescription of Trogoderma fasciolata Fairmaire, 1897, comb. rev. from Madagascar (Coleoptera: Dermestidae, Megatomini).  

PubMed

Trogoderma fasciolata Fairmaire, 1897, comb. rev. is redescribed, illustrated and restored to the genus Trogoderma Dejean, 1821 from Aethriostoma Motschulsky, 1858. A key to the known Trogoderma species from Madagascar is presented. PMID:25781265

Kadej, Marcin; Háva, Ji?í

2015-01-01

226

The applications of comb polymer to the study of liver cell adhesion and signaling  

E-print Network

Comb polymer, which consists of a hydrophobic poly(methyl methacrylate) (PMMA) backbone with hydrophilic hydroxy-poly(ethylene oxide) (HPOEM) side chains, is a tool that has many possible applications for the study of liver ...

Yin, David, 1973-

2004-01-01

227

Applications and noise properties of high repetition rate : TiSapphire frequency combs  

E-print Network

Femtosecond mode-locked lasers are a unique laser technology due to their broad optical bandwidth and potential for linking the optical and radio frequency domains when these lasers are configured as frequency combs. ...

Benedick, Andrew John

2011-01-01

228

An octave-spanning mid-infrared frequency comb generated in a silicon nanophotonic wire waveguide  

PubMed Central

Laser frequency combs, sources with a spectrum consisting of hundred thousands evenly spaced narrow lines, have an exhilarating potential for new approaches to molecular spectroscopy and sensing in the mid-infrared region. The generation of such broadband coherent sources is presently under active exploration. Technical challenges have slowed down such developments. Identifying a versatile highly nonlinear medium for significantly broadening a mid-infrared comb spectrum remains challenging. Here we take a different approach to spectral broadening of mid-infrared frequency combs and investigate CMOS-compatible highly nonlinear dispersion-engineered silicon nanophotonic waveguides on a silicon-on-insulator chip. We record octave-spanning (1,500–3,300?nm) spectra with a coupled input pulse energy as low as 16?pJ. We demonstrate phase-coherent comb spectra broadened on a room-temperature-operating CMOS-compatible chip. PMID:25697764

Kuyken, Bart; Ideguchi, Takuro; Holzner, Simon; Yan, Ming; Hänsch, Theodor W.; Van Campenhout, Joris; Verheyen, Peter; Coen, Stéphane; Leo, Francois; Baets, Roel; Roelkens, Gunther; Picqué, Nathalie

2015-01-01

229

Comb-calibrated solar spectroscopy through a multiplexed single-mode fiber channel  

NASA Astrophysics Data System (ADS)

We investigate a new scheme for astronomical spectrograph calibration using the laser frequency comb at the Solar Vacuum Tower Telescope on Tenerife. Our concept is based upon a single-mode fiber channel, that simultaneously feeds the spectrograph with comb light and sunlight. This yields nearly perfect spatial mode matching between the two sources. In combination with the absolute calibration provided by the frequency comb, this method enables extremely robust and accurate spectroscopic measurements. The performance of this scheme is compared to a sequence of alternating comb and sunlight, and to absorption lines from Earth’s atmosphere. We also show how the method can be used for radial-velocity detection by measuring the well-explored 5 min oscillations averaged over the full solar disk. Our method is currently restricted to solar spectroscopy, but with further evolving fiber-injection techniques it could become an option even for faint astronomical targets.

Probst, R. A.; Wang, L.; Doerr, H.-P.; Steinmetz, T.; Kentischer, T. J.; Zhao, G.; Hänsch, T. W.; Udem, Th; Holzwarth, R.; Schmidt, W.

2015-02-01

230

Osho - Insights on sex  

PubMed Central

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. PMID:23858266

Nagaraj, Anil Kumar Mysore

2013-01-01

231

Osho - Insights on sex.  

PubMed

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. PMID:23858266

Nagaraj, Anil Kumar Mysore

2013-01-01

232

Optimal shape design of an electrostatic comb drive in microelectromechanical systems  

Microsoft Academic Search

Polynomial driving-force comb drives are synthesized using numerical simulation. The electrode shapes are obtained using the indirect boundary element method. Variable-gap comb drives that produce combinations of linear, quadratic, and cubic driving-force profiles are synthesized. This inverse problem is solved by an optimization procedure. Sensitivity analysis is carried out by the direct differentiation approach (DDA) in order to compute design

Wenjing Ye; Subrata Mukherjee; Noel C. MacDonald

1998-01-01

233

Optimally coherent kerr combs generated with crystalline whispering gallery mode resonators for ultrahigh capacity fiber communications.  

PubMed

Optical Kerr frequency combs are known to be effective coherent multiwavelength sources for ultrahigh capacity fiber communications. These combs are the frequency-domain counterparts of a wide variety of spatiotemporal dissipative structures, such as cavity solitons, chaos, or Turing patterns (rolls). In this Letter, we demonstrate that Turing patterns, which correspond to the so-called primary combs in the spectral domain, are optimally coherent in the sense that for the same pump power they provide the most robust carriers for coherent data transmission in fiber communications using advanced modulation formats. Our model is based on a stochastic Lugiato-Lefever equation which accounts for laser pump frequency jitter and amplified spontaneous emission noise induced by the erbium-doped fiber amplifier. Using crystalline whispering-gallery-mode resonators with quality factor Q?10^{9} for the comb generation, we show that when the noise is accounted for, the coherence of a primary comb is significantly higher than the coherence of their solitonic or chaotic counterparts for the same pump power. In order to confirm this theoretical finding, we perform an optical fiber transmission experiment using advanced modulation formats, and we show that the coherence of the primary comb is high enough to enable data transmission of up to 144??Gbit/s per comb line, the highest value achieved with a Kerr comb so far. This performance evidences that compact crystalline photonic systems have the potential to play a key role in a new generation of coherent fiber communication networks, alongside fully integrated systems. PMID:25793816

Pfeifle, Joerg; Coillet, Aurélien; Henriet, Rémi; Saleh, Khaldoun; Schindler, Philipp; Weimann, Claudius; Freude, Wolfgang; Balakireva, Irina V; Larger, Laurent; Koos, Christian; Chembo, Yanne K

2015-03-01

234

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

E-print Network

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 Fourier transform.

Hipke, Arthur; Ideguchi, Takuro; Hänsch, Theodor W; Picqué, Nathalie

2013-01-01

235

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

236

Generation of Kerr combs in MgF2 and CaF2 microresonators  

Microsoft Academic Search

We report on a study of hyper-parametric oscilla- tion in high-Q calcium fluoride and magnesium fluoride optical microresonators, and show that, magnesium fluoride microres- onators generate wider Raman-free Kerr frequency combs at telecom wavelengths, in contrast with calcium fluoride ones. We observed 30 nm wide frequency combs in magnesium fluoride microresonators pumped with only 2 mW of continuous wave 1543

W. Liang; A. B. Matsko; A. A. Savchenkov; V. S. Ilchenko; D. Seidel; L. Maleki

2011-01-01

237

Raman optical frequency comb generation in hydrogen-filled hollow-core fiber  

NASA Astrophysics Data System (ADS)

In this dissertation, we demonstrate the generation of optical Raman frequency combs by a single laser pump pulse traveling in hydrogen-filled hollow-core optical fibers. This comb generation process is a cascaded stimulated Raman scattering effect, where higher-order sidebands are produced by lower orders scattered from hydrogen molecules. We observe more than 4 vibrational and 20 rotational Raman sidebands in the comb. They span more than three octaves in optical wavelength, largely thanks to the broadband transmission property of the fiber. We found that there are phase correlations between the generated Raman comb sidebands (spectral lines), although their phases are fluctuating from one pump pulse to another due to the inherit spontaneous initiation of Raman scattering. In the experiment, we generated two Raman combs independently from two fibers and simultaneously observed the single-shot interferences between Stokes and anti-Stokes components from the two fibers. The experimental results clearly showed the strong phase anti-correlation between first-order side bands. We also developed a quantum theory to describe this Raman comb generation process, and it predicts and explains the phase correlations we observe. The phase correlation that we found in optical Raman combs may allow us to synthesize single-cycle optical pulse trains, creating attosecond pulses. However, the vacuum fluctuation in stimulated Raman scattering will result in the fluctuation of carrier envelope phase of the pulse trains. We propose that we can stabilize the comb by simultaneously injecting an auxiliary optical beam, mutually coherent with the main Raman pump laser pulse, which is resonant with the third anti-Stokes field.

Wu, Chunbai

238

Generation of wideband frequency combs by continuous-wave seeding of multistage mixers with synthesized dispersion.  

PubMed

We numerically and experimentally demonstrate efficient generation of an equalized optical comb with 150-nm bandwidth. The comb was generated by low-power, continuous-wave seeds, eliminating the need for pulsed laser sources. The new architecture relies on efficient creation of higher-order mixing tones in phase-matched nonlinear fiber stages separated by a linear compressor. Wideband generation was enabled by precise dispersion engineering of multiple-stage parametric mixers. PMID:22330571

Myslivets, Evgeny; Kuo, Bill P P; Alic, Nikola; Radic, Stojan

2012-01-30

239

Methyl-combing: single-molecule analysis of DNA methylation on stretched DNA fibers.  

PubMed

The methyl-combing technique combines the dynamic molecular combing method with the detection of DNA modifications. The assay allows the single-molecule analysis of epigenetic marks on regularly stretched DNA fibers, at the megabase scale with kilobase resolution. The protocol presented in this chapter is based on proof-of-principle experiments where the single-molecule detection of DNA methylation has been performed on unmethylated and in vitro methylated ? phage DNA. PMID:24162992

Németh, Attila

2014-01-01

240

Efficient polyphase decomposition of comb decimation filters in ?▵ analog-to-digital converters  

Microsoft Academic Search

A power efficient multirate multistage Comb decimation filter for mono-bit and multi-bit ?▵ A\\/D converters is presented. Polyphase decomposition in all stages, with high decimation factor in the first stage, is used to significantly reduce the sampling frequency of the Comb filter. Several implementations indicate that proper choice of the first stage decimation factor can considerably improve power consumption, area

Hassan Aboushady; Yannick Dumonteix; Marie-Minerve Louërat; Habib Mehrez

2001-01-01

241

Sex differences in same-sex friendship  

Microsoft Academic Search

Two studies examined sex differences in the same-sex friendships of college men and women. In a questionnaire study, self-reports were obtained of number of friends and frequency of interaction, typical and preferred kinds of interactions with friends, and emotional intimacy. A role-play study provided more direct information about conversations between friends. Men and women did not differ in quantitative aspects

Mayta A. Caldwell; Letitia Anne Peplau

1982-01-01

242

Modeling of a high force density fishbone shaped electrostatic comb drive microactuator.  

PubMed

This paper presents the design and evaluation of a high force density fishbone shaped electrostatic comb drive actuator. This comb drive actuator has a branched structure similar to a fishbone, which is intended to increase the capacitance of the electrodes and hence increase the electrostatic actuation force. Two-dimensional finite element analysis was used to simulate the motion of the fishbone shaped electrostatic comb drive actuator and compared against the performance of a straight sided electrostatic comb drive actuator. Performances of both designs are evaluated by comparison of displacement and electrostatic force. For both cases, the active area and the minimum gap distance between the two electrodes were constant. An active area of 800 × 300 ?m, which contained 16 fingers of fishbone shaped actuators and 40 fingers of straight sided actuators, respectively, was used. Through simulation, improvement of drive force of the fishbone shaped electrostatic comb driver is approximately 485% higher than conventional electrostatic comb driver. These results indicate that the fishbone actuator design provides good potential for applications as high force density electrostatic microactuator in MEMS systems. PMID:25165751

Megat Hasnan, Megat Muhammad Ikhsan; Mohd Sabri, Mohd Faizul; Mohd Said, Suhana; Nik Ghazali, Nik Nazri

2014-01-01

243

Modeling of a High Force Density Fishbone Shaped Electrostatic Comb Drive Microactuator  

PubMed Central

This paper presents the design and evaluation of a high force density fishbone shaped electrostatic comb drive actuator. This comb drive actuator has a branched structure similar to a fishbone, which is intended to increase the capacitance of the electrodes and hence increase the electrostatic actuation force. Two-dimensional finite element analysis was used to simulate the motion of the fishbone shaped electrostatic comb drive actuator and compared against the performance of a straight sided electrostatic comb drive actuator. Performances of both designs are evaluated by comparison of displacement and electrostatic force. For both cases, the active area and the minimum gap distance between the two electrodes were constant. An active area of 800 × 300??m, which contained 16 fingers of fishbone shaped actuators and 40 fingers of straight sided actuators, respectively, was used. Through simulation, improvement of drive force of the fishbone shaped electrostatic comb driver is approximately 485% higher than conventional electrostatic comb driver. These results indicate that the fishbone actuator design provides good potential for applications as high force density electrostatic microactuator in MEMS systems. PMID:25165751

Megat Hasnan, Megat Muhammad Ikhsan; Mohd Sabri, Mohd Faizul; Mohd Said, Suhana; Nik Ghazali, Nik Nazri

2014-01-01

244

On-chip frequency comb generation at visible wavelengths via simultaneous second- and third-order optical nonlinearities.  

PubMed

Microresonator-based frequency comb generation at or near visible wavelengths would enable applications in precise optical clocks, frequency metrology, and biomedical imaging. Comb generation in the visible has been limited by strong material dispersion and loss at short wavelengths, and only very narrowband comb generation has reached below 800 nm. We use the second-order optical nonlinearity in an integrated high-Q silicon nitride ring resonator cavity to convert a near-infrared frequency comb into the visible range. We simultaneously demonstrate parametric frequency comb generation in the near-infrared, second-harmonic generation, and sum-frequency generation. We measure 17 comb lines converted to visible wavelengths extending to 765 nm. PMID:25401803

Miller, Steven; Luke, Kevin; Okawachi, Yoshitomo; Cardenas, Jaime; Gaeta, Alexander L; Lipson, Michal

2014-11-01

245

Highly precise stabilization of intracavity prism-based Er:fiber frequency comb using optical-microwave phase detector.  

PubMed

In this Letter, we demonstrate a fully stabilized Er:fiber frequency comb by using a fiber-based, high-precision optical-microwave phase detector. To achieve high-precision and long-term phase locking of the repetition rate to a microwave reference, frequency control techniques (tuning pump power and cavity length) are combined together as its feedback. Since the pump power has been used for stabilization of the repetition rate, we introduce a pair of intracavity prisms as a regulator for carrier-envelope offset frequency, thereby phase locking one mode of the comb to the rubidium saturated absorption transition line. The stabilized comb performs the same high stability as the reference for the repetition rate and provides a residual frequency instability of 3.6×10(-13) for each comb mode. The demonstrated stabilization scheme could provide a high-precision comb for optical communication, direct frequency comb spectroscopy. PMID:25490492

Zhang, Shuangyou; Wu, Jiutao; Leng, Jianxiao; Lai, Shunnan; Zhao, Jianye

2014-11-15

246

Optimal timing of comb construction by honeybee ( Apis mellifera ) colonies: a dynamic programming model and experimental tests  

Microsoft Academic Search

Honeybee colonies, like organisms, should exhibit optimal design in their temporal pattern of resource allocation to somatic\\u000a structures. A vital colony structure is the comb which stores honey for overwinter survival. However, the timing of comb construction\\u000a poses a dilemma to a colony attempting to maximize its honey reserves. On the one hand, plenty of empty comb is needed for

Stephen C. Pratt

1999-01-01

247

Vertical-actuated electrostatic comb drive with in situ capacitive position correction for application in phase shifting diffraction interferometry  

Microsoft Academic Search

This research utilizes the levitation effect of electrostatic comb fingers to design vertical-to-the-substrate actuation for optical phase shifting interferometry applications. For typical polysilicon comb drives with 2 ?m gaps between the stationary and moving fingers, as well as between the microstructures and the substrate, the equilibrium position is nominally 1-2 ?m above the stationary comb fingers. This distance is ideal

Abraham P. Lee; Charles F. McConaghy; Gary Sommargren; Peter Krulevitch; Eugene W. Campbell

2003-01-01

248

On the generation of octave-spanning optical frequency combs using monolithic whispering-gallery-mode microresonators.  

PubMed

Octave-spanning optical frequency combs are especially interesting in optical metrology owing to the ability of self-referencing. We report a theoretical study on the generation of octave-spanning combs in the whispering gallery modes of a microresonator. Through a modal expansion model simulation in a calcium fluoride microcavity, we show that a combination of suitable pump power, Kerr nonlinearity, and dispersion profile can lead to stable and robust octave-spanning optical frequency combs. PMID:20717427

Chembo, Yanne K; Yu, Nan

2010-08-15

249

Colony development and establishment of the fungus comb in Microtermes sp. nr. Usambaricus (Sjöstedt) (Isoptera: Macrotermitinae) from Nigeria  

Microsoft Academic Search

Summary Incipient colonies of the fungus-growing termiteMicrotermes sp. nr.usambaricus (Macrotermitinæ) have been successfully cultured in the laboratory up to the stage where a viable fungus comb was established. The primordial fungus comb is inoculated with fungusTermitomyces by the female reproductive which ingests asexual spores (conidia) from the comb before leaving the parental nest. These conidia survive in the digestive tube

R. A. Johnson

1981-01-01

250

A self-aligned fabrication method of dual comb drive using multilayers SOI process for optical MEMS applications  

Microsoft Academic Search

A novel method for fabricating a self-aligned electrostatic dual comb drive using a multi-layer SOI process is developed. The present method utilizes four aligned masks, greatly simplify the existing SOI-MEMS fabrication methods in manufacturing optical MEMS devices. Here, the actuating structure consists of fixed combs and moving combs that are composed of single crystal silicon, nitride and polysilicon. One mask

W. T. Lin; J. C. Chiou; C. Tsou

2005-01-01

251

Calculation of a slow-wave system of the twisted double comb type in a cylindrical shield  

NASA Astrophysics Data System (ADS)

A method is proposed for calculating the parameters of slow-wave systems of the double comb type in a shield with a helical axis of symmetry from the known calculated parameters of a double comb with a rotational axis of symmetry. As an example, the parameters of a slow-wave system of the twisted double comb type are calculated using a program for calculating strip-type slow-wave structures by the multiple-conductor method.

Karpenko, Iu. V.; Guttsait, E. M.

1989-05-01

252

Sex, epilepsy, and epigenetics.  

PubMed

Epilepsy refers to a heterogeneous group of disorders that are associated with a wide range of pathogenic mechanisms, seizure manifestations, comorbidity profiles, and therapeutic responses. These characteristics are all influenced quite significantly by sex. As with other conditions exhibiting such patterns, sex differences in epilepsy are thought to arise-at the most fundamental level-from the "organizational" and "activational" effects of sex hormones as well as from the direct actions of the sex chromosomes. However, our understanding of the specific molecular, cellular, and network level processes responsible for mediating sex differences in epilepsy remains limited. Because increasing evidence suggests that epigenetic mechanisms are involved both in epilepsy and in brain sexual dimorphism, we make the case here that analyzing epigenetic regulation will provide novel insights into the basis for sex differences in epilepsy. PMID:24998474

Qureshi, Irfan A; Mehler, Mark F

2014-12-01

253

Pseudooceanicola atlanticus gen. nov. sp. nov., isolated from surface seawater of the Atlantic Ocean and reclassification of Oceanicola batsensis, Oceanicola marinus, Oceanicola nitratireducens, Oceanicola nanhaiensis, Oceanicola antarcticus and Oceanicola flagellatus, as Pseudooceanicola batsensis comb. nov., Pseudooceanicola marinus comb. nov., Pseudooceanicola nitratireducens comb. nov., Pseudooceanicola nanhaiensis comb. nov., Pseudooceanicola antarcticus comb. nov., and Pseudooceanicola flagellatus comb. nov.  

PubMed

A taxonomic study was carried out on strain 22II-S11g(T), which was isolated from the surface seawater of the Atlantic Ocean. The bacterium was found to be Gram-negative, rod shaped without flagellum, oxidase positive and weakly catalase positive. Growth was observed at NaCl concentrations of 0.5-9 % and at temperatures of 10-41 °C. The isolate was incapable of gelatin hydrolysis and unable to reduce nitrate to nitrite, degrade aesculin and Tween 80. On the basis of 16S rRNA gene sequence similarity, strain 22II-S11g(T) was found to be most closely related to Oceanicola batsensis HTCC2597(T) (97.26 %), followed by Oceanicola nitratireducens JLT1210(T) (96.39 %), whilst other species of genus Oceanicola shared 94.00-96.34 % sequence similarity. However, it showed low similarity to Oceanicola granulosus HTCC2516(T) (94.79 %), the type species of the genus Oceanicola. Phylogenetic analysis showed that strain 22II-S11g(T) formed a clade with six species currently classified in the genus Oceanicola, but strain O. granulosus HTCC2516(T) and strain O. litoreus M-M22(T) clustered with two other genera respectively. The ANI values between strain 22II-S11g(T) and two type strains (O. batsensis HTCC2597(T) and O. granulosus HTCC2516(T)) are 91.86 and 91.81 % respectively. The digital DNA-DNA hybridization estimate values between strain 22II-S11g(T) and two type strains (O. batsensis HTCC2597(T) and O. granulosus HTCC2516(T)) are 23.4 ± 2.4 and 20.0 ± 2.3 %, respectively. The principal fatty acids were identified as summed feature 8 (C18:1 ?7c/?6c), C16:0, C18:1 ?7c11-methyl and C12:0 3OH. The G+C content determined from the draft genome sequence is 64.1 mol%. The respiratory quinone was determined to be Q-10 (100 %). Phosphatidylethanolamine, phosphatidylglycerol, an aminolipid, phosphatidylcholine, a phospholipid and three lipids were identified in the polar lipids. The combined genotypic and phenotypic data also show that strain 22II-S11g(T) should not be assigned to the genus Oceanicola; consequently strain 22II-S11g(T) is concluded to represent a novel species of a novel genus in the family Rhodobacteraceae, for which the name Pseudooceanicola atlanticus gen. nov., sp. nov. is proposed (type strain 22II-S11g(T) = KCTC 42004(T) = LMG 27424(T) = MCCC 1A09160(T)). Six misclassified species should be transferred to the novel genus Pseudooceanicola as follows: O. batsensis should be transferred to the genus Pseudooceanicola as Pseudooceanicola batsensis comb. nov. (type strain HTCC2597(T) = ATCC BAA-863(T) = DSM 15984(T) = KCTC 12145(T)); Oceanicola marinus should be transferred to the genus Pseudooceanicola as Pseudooceanicola marinus comb. nov. (type strain AZO-C(T) = LMG 23705(T) = BCRC 17591(T)); O. nitratireducens should be transferred to the genus Pseudooceanicola as Pseudooceanicola nitratireducens comb. nov. (type strain JLT1210(T) = LMG 24663(T) = CGMCC 1.7292(T)); Oceanicola nanhaiensis should be transferred to the genus Pseudooceanicola as Pseudooceanicola nanhaiensis comb. nov. (type strain SS011B1-20(T) = LMG 23508(T) = CGMCC 1.6293(T)); Oceanicola antarcticus should be transferred to the genus Pseudooceanicola as Pseudooceanicola antarcticus comb. nov. (type strain Ar-45(T) = CGMCC 1.12662(T) = LMG 27868(T)); and Oceanicola flagellatus should be transferred to the genus Pseudooceanicola as Pseudooceanicola flagellatus comb. nov. (type strain DY470(T) = CGMCC 1.12664(T) = LMG 27871(T)). PMID:25663028

Lai, Qiliang; Li, Guizhen; Liu, Xiupian; Du, Yaping; Sun, Fengqin; Shao, Zongze

2015-04-01

254

Abnormalities of Sex Differentiation  

Microsoft Academic Search

Sex differentiation is determined by a cascade of events proceeding from chromosomal sex to the completion of sexual maturation at puberty. Many factors involved in this cascade have been identified. Here we focus on DAX-1, androgen receptor and cytochrome P450cl7, and discuss their functions in sex differentiation. We analyzed the DAX-1 genes of two unrelated Japanese patients with congenital adrenal

Hajime Nawata; Ryoichi Takayanagi; Toshihiko Yanase; Shoichiro Ikuyama; Taijirou Okabe

1996-01-01

255

Temperature Sex Reversal Implies Sex Gene Dosage in a Reptile  

E-print Network

Temperature Sex Reversal Implies Sex Gene Dosage in a Reptile Alexander E. Quinn,1 * Arthur Georges by genes on sex chromo- somes in many vertebrates [genotypic sex determination (GSD)], but may also be determined by temperature during embryonic development [temperature-dependent sex de- termination (TSD)] (1

Canberra, University of

256

Sex Education and Its Influences on College Sex Practices  

Microsoft Academic Search

This was a relational study to examine the possibly of a correlation between type of high school sex education and types of attitudes and behaviors towards sex within the context of the college social environment. A review of the literature shows that comprehensive sex education has been more effective than no sex education or abstinence only sex education in delaying

Matthew Yetsko

2011-01-01

257

Regeneration of ciliary comb plates in the ctenophore Mnemiopsis leidyi. i. morphology.  

PubMed

Regeneration of missing body parts in model organisms provides information on the mechanisms underlying the regeneration process. The aim here is to use ctenophores to investigate regeneration of their giant ciliary swimming plates. When part of a row of comb plates on Mnemiopsis is excised, the wound closes and heals, greatly increasing the distance between comb plates near the former cut edges. Video differential interference contrast (DIC) microscopy of the regeneration of new comb plates between widely separated plates shows localized widenings of the interplate ciliated groove (ICG) first, followed by growth of two opposing groups of comb plate cilia on either side. The split parts of a new plate elongate as their bases extend laterally away from the ICG widening and continue ciliogenesis at both ends. The split parts of a new plate grow longer and move closer together into the ICG widening until they merge into a single plate that interrupts the ICG in a normal manner. Video DIC snapshots of dissected gap preparations 1.5-3-day postoperation show that ICG widenings and/or new plates do not all appear at the same time or with uniform spacing within a gap: the lengths and distances between young plates in a gap are quite variable. Video stereo microscopy of intact animals 3-4 days after the operation show that all the new plates that will form in a gap are present, fairly evenly spaced and similar in length, but smaller and closer together than normal. Normal development of comb plates in embryos and growing animals is compared to the pattern of comb plate regeneration in adults. Comb plate regeneration differs in the cydippid Pleurobrachia that lacks ICGs and has a firmer mesoglea than Mnemiopsis. This study provides a morphological foundation for histological, cellular, and molecular analysis of ciliary regeneration in ctenophores. PMID:21987455

Tamm, Sidney L

2012-01-01

258

Calcium control of ciliary reversal in ionophore-treated and ATP- reactivated comb plates of ctenophores  

PubMed Central

Previous work showed that ctenophore larvae swim backwards in high-KCl seawater, due to a 180 degrees reversal in the direction of effective stroke of their ciliary comb plates (Tamm, S. L., and S. Tamm, 1981, J. Cell Biol., 89: 495-509). Ion substitution and blocking experiments indicated that this response is Ca2+ dependent, but comb plate cells are innervated and presumably under nervous control. To determine whether Ca2+ is directly involved in activating the ciliary reversal mechanism and/or is required for synaptic triggering of the response, we (a) determined the effects of ionophore A23187 and Ca2+ on the beat direction of isolated nerve-free comb plates dissociated from larvae by hypotonic, divalent cation-free medium, and (b) used permeabilized ATP- reactivated models of comb plates to test motile responses to known concentrations of free Ca2+. We found that 5 microM A23187 and 10 mM Ca2+ induced dissociated comb plate cells to beat in the reverse direction and to swim counterclockwise in circular paths instead of in the normal clockwise direction. Detergent/glycerol-extracted comb plates beat actively in the presence of ATP, and reactivation was reversibly inhibited by micromolar concentrations of vanadate. Free Ca2+ concentrations greater than 10(-6)M caused reversal in direction of the effective stroke but no significant increase in beat frequency. These results show that ciliary reversal in ctenophores, like that in protozoa, is activated by an increase in intracellular free Ca2+ ions. This allows the unique experimental advantages of ctenophore comb plate cilia to be used for future studies on the site and mechanism of action of Ca2+ in the regulation of ciliary motion. PMID:3921553

1985-01-01

259

MECHANISMS FOR BRAIN SEX DIFFERENTIATION  

Microsoft Academic Search

Distinctive sex differences in reproductive behavior and physiology have been attributed not to differences in hormones ~onad secretes in each sex but differences in particuhr brain structures. Interestingly enough. brain sex difference is determined mostly by gonadal hormones during ontogeny independent of genetic sex. In many laboratory mammals. brain sex can be manipulated at a particular stage of omogeny called

Yasuo Sakuma

2007-01-01

260

Sex: Making the Right Decision  

MedlinePLUS

MENU Return to Web version Sex: Making the Right Decision Sex: Making the Right Decision What is sex? The word sex is used in several ways. It can refer ... by the penis. It also can mean what sex you were born (male or female) or physical ...

261

Nonvolitional Sex and Sexual Health  

Microsoft Academic Search

Nonvolitional sex is sexual behavior that violates a person's right to choose when and with whom to have sex and what sexual behaviors to engage in. The more extreme forms of this behavior include rape, forced sex, childhood sexual abuse, sex trafficking, and violence against people with nonconventional sexual identities. More nuanced forms of nonvolitional sex include engaging in sexual

Debra Kalmuss

2004-01-01

262

The Assembly of Nanorods in Comb Polymer Supramolecules  

NASA Astrophysics Data System (ADS)

Inorganic nanoparticles exhibit a wide range of size-dependent properties and present great promise in technological applications. Fully harnessing this potential requires developing bottom-up strategies to assemble nanoparticles over multiple length scales simultaneously. Nanoparticles have been co-assembled with block copolymers (BCPs). Often this approach requires delicate balance between particle-polymer interactions and entropic penalty associated with polymer chain deformation upon particle incorporation. Recently, we showed that a coil-comb supramolecule formed by non- covalent attachment of small molecule amphiphiles to one block of a BCP can be used to direct nanoparticle assemblies with high precision. The alkyl tail of the small molecules chosen interacts favorably with the native alkyl ligands of a wide variety of inorganic nanoparticles and eliminates the need for particle surface modification. Upon attaching small molecule to one BCP block, the polymer chain stiffens, providing entropic driving force to further direct nanoparticle organization within BCP microdomains. Here, the co-assembly of these supramolecules with nanorods was systematically investigated as a function of small molecule loading, supramolecular morphology, nanorod diameter, and aspect ratio. The presented fundamental studies pave a path toward nanorod-based device fabrication.

Mastroianni, Alexander; Thorkelsson, Kari; Luther, Joseph; Alivisatos, Paul; Xu, Ting

2010-03-01

263

Brillouin Stokes comb generated in a distributed fiber Raman amplifier  

NASA Astrophysics Data System (ADS)

A Brillouin Stokes comb laser with increased flatness is reported. The feedback for the laser is provided by a distributed mirror combined with a narrowband seed laser. The Brillouin seed power and wavelength optimization is crucial in order to obtain a uniform power level between Stokes lines. The Brillouin seed must have a relatively large power and its wavelength must be located close to the Raman peak gain region. The flat-amplitude bandwidth is also determined by the choice of Raman pump wavelength. A flat-amplitude bandwidth of 34 nm from 1538 nm to 1572 nm is measured when Raman pump wavelength is set to 1455 nm. 425 uniform Brillouin Stokes lines with 0.08 nm spacing are generated across the wavelength range. The average signal-to-noise ratio of 15 dB is obtained for all the Brillouin Stokes lines. This type of laser can be used in optical communications as a multiwavelength source and also in metrology as a frequency ruler.

Martins, Hugo F.; Marques, Manuel B.; Frazão, Orlando

2011-05-01

264

The Comb Jelly Opsins and the Origins of Animal Phototransduction  

PubMed Central

Opsins mediate light detection in most animals, and understanding their evolution is key to clarify the origin of vision. Despite the public availability of a substantial collection of well-characterized opsins, early opsin evolution has yet to be fully understood, in large part because of the high level of divergence observed among opsins belonging to different subfamilies. As a result, different studies have investigated deep opsin evolution using alternative data sets and reached contradictory results. Here, we integrated the data and methods of three, key, recent studies to further clarify opsin evolution. We show that the opsin relationships are sensitive to outgroup choice; we generate new support for the existence of Rhabdomeric opsins in Cnidaria (e.g., corals and jellyfishes) and show that all comb jelly opsins belong to well-recognized opsin groups (the Go-coupled opsins or the Ciliary opsins), which are also known in Bilateria (e.g., humans, fruit flies, snails, and their allies) and Cnidaria. Our results are most parsimoniously interpreted assuming a traditional animal phylogeny where Ctenophora are not the sister group of all the other animals. PMID:25062921

Feuda, Roberto; Rota-Stabelli, Omar; Oakley, Todd H.; Pisani, Davide

2014-01-01

265

The comb jelly opsins and the origins of animal phototransduction.  

PubMed

Opsins mediate light detection in most animals, and understanding their evolution is key to clarify the origin of vision. Despite the public availability of a substantial collection of well-characterized opsins, early opsin evolution has yet to be fully understood, in large part because of the high level of divergence observed among opsins belonging to different subfamilies. As a result, different studies have investigated deep opsin evolution using alternative data sets and reached contradictory results. Here, we integrated the data and methods of three, key, recent studies to further clarify opsin evolution. We show that the opsin relationships are sensitive to outgroup choice; we generate new support for the existence of Rhabdomeric opsins in Cnidaria (e.g., corals and jellyfishes) and show that all comb jelly opsins belong to well-recognized opsin groups (the Go-coupled opsins or the Ciliary opsins), which are also known in Bilateria (e.g., humans, fruit flies, snails, and their allies) and Cnidaria. Our results are most parsimoniously interpreted assuming a traditional animal phylogeny where Ctenophora are not the sister group of all the other animals. PMID:25062921

Feuda, Roberto; Rota-Stabelli, Omar; Oakley, Todd H; Pisani, Davide

2014-08-01

266

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

SciTech Connect

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.

Strecker, Kevin E.; Chandler, David W.

2010-10-01

267

Reclassification of Ruminococcus obeum as Blautia obeum comb. nov.  

PubMed

During our previous studies we reclassified Clostridium coccoides and a number of misclassified ruminococci into a novel genus Blautia within the family Lachnospiraceae. However, the Rules of the Bacteriological Code currently require that the types of all species and subspecies with new names (including new combinations) be deposited in two different collections in two different countries. The type strain of Ruminococcus obeum was, at that period in time, only deposited in the American Type Culture Collection (ATCC) and a second independent deposit, as required by the Code, was not available. Consequently, the transfer of this species to the genus Blautia could not be made, because the resulting species name would not conform to the Rules governing the valid publication of species names and deposit of type material (Rules 27 and 30) and consequently would not be considered to be validly published. This resulted in a nomenclatural and taxonomic anomaly with R. obeum being phylogenetically placed among members of the genus Blautia with 16S rRNA gene sequence similarities of between 91.8 and 96.6?%. In order to rectify this unsatisfactory situation, through our discussions with the ATCC, the deposit of strain R. obeum ATCC 29174(T) to the DSMZ as strain number DSM 25238(T) was completed. Hence, the transfer of R. obeum to the genus Blautia as Blautia obeum comb. nov. is now proposed. The type strain is ATCC 29174(T) (?=?DSM 25238(T)?=?KCTC 15206(T)). PMID:25481290

Lawson, Paul A; Finegold, Sydney M

2015-03-01

268

Cationic comb-type copolymers for DNA analysis  

NASA Astrophysics Data System (ADS)

Genetic diagnoses, such as single nucleotide polymorphism (SNP) typing, allow elucidation of gene-based physiological differences, such as susceptibility to diseases and response to drugs, among individuals. Many detection technologies, including allele-specific hybridization, allele-specific primer extension and oligonucleotide ligation, are being used to discriminate SNP alleles. These methods still have many unsolved practical issues. In general they require adequate and specific hybridizations of primer or probe DNAs with target DNAs. This frequently needs optimization of the probe/primer structures and operating conditions. In nature, highly homology-sensitive hybridization is assisted by a nucleic acid chaperone that reduces the energy barrier associated with breakage and reassociation of nucleic base pairs. Here we report a simple, quick, precise but enzyme-free method for SNP analysis. The method uses cationic comb-type copolymers (CCCs) producing high nucleic acid chaperone activities. A single-base mismatch in 20-mer DNA can be detected within a few minutes at ambient temperatures (25-37 °C). Even without careful optimization processes, the method has the sensitivity to detect the mismatches causing subtle changes (?Tm ~ 1 °C) in duplex thermal stability. CCCs may have various bioanalytical applications where precise hybridization of nucleic acids is needed.

Kim, Won Jong; Sato, Yuichi; Akaike, Toshihiro; Maruyama, Atsushi

2003-12-01

269

Sex Differentiation and Schooling.  

ERIC Educational Resources Information Center

Discussed are the effects of sex-stereotyping on achievement and self-concept in science and mathematics students. Although parents rarely treat sons and daughters differently, other adults, especially teachers, tend to sex-stereotype students. It is suggested that multiple-choice testing discriminates in favor or boys. (JN)

Harding, Jan

1980-01-01

270

Attitudes Towards Premarital Sex  

NSDL National Science Digital Library

This activity is used in a General Sociology class for undergraduate students. This activity looks attitudes towards prematiral sex in the U.S. by race, sex, age, political party and education. This activity uses General Social Survey data provided on the Wadsworth Publishing Company website. See instructions in the exercise documents under teaching materials to open the data analyzer.

Tracy Dietz

271

The sex killer  

Microsoft Academic Search

Thirteen sex killers were compared to 13 nonsex killers and 13 nonhomicidal sexually aggressive men on sexual history, substance abuse, history of violence, mental illness and personality, brain pathology and endocrine abnormalities. There were more similarities among the three groups than differences. Among the findings, the presence of transvestism and the early appearance of sadism differentiated the sex killers from

R. Langevin; M. H. Ben-Aron; P. Wright; V. Marchese; L. Handy

1988-01-01

272

Cytological sexing of cetacea  

Microsoft Academic Search

A biopsy dart, that can be shot from a gun or crossbow, was developed to obtain skin of whales at sea. Determination of sex was found possible by staining and locating sex chromatin bodies in the nuclei of female skin cells. This procedure will be useful in many types of field studies on whales.

H. E. Winn; W. L. Bischoff; A. G. Taruski

1973-01-01

273

Sex during Pregnancy  

MedlinePLUS

... for miscarriage or premature delivery multiple fetuses (twins, triplets, etc.) Back Continue Common Questions and Concerns These are some of the most frequently asked questions about sex during pregnancy. Can sex harm my baby? No. Your baby is fully protected by the ...

274

Mid-infrared optical frequency combs at 2.5??m based on crystalline microresonators  

PubMed Central

The mid-infrared spectral range (?~2–20??m) is of particular importance as many molecules exhibit strong vibrational fingerprints in this region. Optical frequency combs—broadband optical sources consisting of equally spaced and mutually coherent sharp lines—are creating new opportunities for advanced spectroscopy. Here we demonstrate a novel approach to create mid-infrared optical frequency combs via four-wave mixing in a continuous-wave pumped ultra-high Q crystalline microresonator made of magnesium fluoride. Careful choice of the resonator material and design made it possible to generate a broadband, low-phase noise Kerr comb at ?=2.5??m spanning 200?nm (?10?THz) with a line spacing of 100?GHz. With its distinguishing features of compactness, efficient conversion, large mode spacing and high power per comb line, this novel frequency comb source holds promise for new approaches to molecular spectroscopy and is suitable to be extended further into the mid-infrared. PMID:23299895

Wang, C. Y.; Herr, T.; Del’Haye, P.; Schliesser, A.; Hofer, J.; Holzwarth, R.; Hänsch, T. W.; Picqué, N.; Kippenberg, T. J.

2013-01-01

275

High-resolution spectroscopy using interleaved 100 GHz optical frequency comb scanned by phase modulator  

NASA Astrophysics Data System (ADS)

A high-resolution spectroscopy technique is proposed with an optical phase modulator combined with an interleaved optical frequency comb. The optical phase modulator and a frequency-locked laser light guarantee a spectral resolution less than 1 MHz on an absolute frequency axis. A wide measurement frequency range was realized using a 25 GHz optical frequency comb lying over a 4 THz frequency region. An extraction of single tooth intensity from the comb was realized by a heterodyne technique with a frequency-tunable laser used as a local oscillator. Also, the 25 GHz optical frequency comb was interleaved to generate four 100-GHz combs for removing the crosstalk from the 25 GHz neighboring sidebands in the teeth. This proposed spectroscopy technique was experimentally demonstrated with a resonator of less than 1 MHz linewidth and a H 13C 14N gas cell. Thus, a measurement frequency range higher than 4 THz (1530 nm-1560 nm) was confirmed with an effective spectral resolution 100 kHz order. In addition, the characteristics of the proposed system were compared with those of the previous system with a single-sideband (SSB) optical modulator.

Shioda, Tatsutoshi; Fujii, Kenichiro; Kashiwagi, Ken; Kurokawa, Takashi

2011-10-01

276

CO2 phase and amplitude spectra measured over 2 km outdoor path with a dual-comb spectrometer  

NASA Astrophysics Data System (ADS)

We present dispersive dual-comb spectroscopy of atmospheric CO2 across a 2-km open-air path. By sending a single comb through the open-air path, both molecular phase spectrum and conventional absorbance spectrum are obtained. The measured phase spectra match expected molecular lineshape models.

Coddington, I.; Giorgetta, F. R.; Rieker, G. B.; Swann, W. C.; Zolot, A. M.; Sinclair, L. C.; Baumann, E.; Cromer, C.; Newbury, N. R.

2014-09-01

277

Absolute frequency measurement of an SF6 two-photon line using a femtosecond optical comb and sum-frequency  

E-print Network

Absolute frequency measurement of an SF6 two-photon line using a femtosecond optical comb and sum-frequency to measure IR frequencies near 30 THz using a femtosecond (fs) laser optical comb and sum-frequency generation. The optical frequency is directly compared to the distance between two modes of the fs laser

Paris-Sud XI, Université de

278

Draft Genome Sequence of Empedobacter (Formerly Wautersiella) falsenii comb. nov. Wf282, a Strain Isolated from a Cervical Neck Abscess  

PubMed Central

Empedobacter (formerly Wautersiella) falsenii comb. nov. strain Wf282 was isolated from a cervical neck abscess sample from an 18-year-old female patient. The isolate was resistant to many antibiotics, including meropenem and colistin. The total DNA from the multidrug-resistant E. falsenii comb. nov. Wf282 clinical isolate was sequenced. PMID:25838490

Traglia, German Matías; Dixon, Chelsea; Chiem, Kevin; Almuzara, Marisa; Barberis, Claudia; Montaña, Sabrina; Merino, Cindy; Mussi, María Alejandra; Tolmasky, Marcelo E.; Iriarte, Andres; Vay, Carlos

2015-01-01

279

Absolute frequency measurement of the iodine-stabilized Ar+ at 514.6 nm using a femtosecond optical frequency comb.  

E-print Network

Absolute frequency measurement of the iodine-stabilized Ar+ laser at 514.6 nm using a femtosecond laser frequency comb generator. The measured frequency at an iodine pressure of 0.12 Pa is 67.3(0.75) k frequency comb transfer oscillator. Secondary laser frequency references based on iodine absorption lines

Boyer, Edmond

280

Comparison of Brillouin-Raman comb fiber laser in two different configurations  

NASA Astrophysics Data System (ADS)

The properties of a Brillouin-Raman comb fiber laser are compared for two different configurations: co-propagating and counter-propagating Raman pump. The optical spectrum is compared for changing the Raman pump power and the power or the wavelength of seed laser. A Brillouin-Raman comb with 400 linewidth lasers in a flat-amplitude bandwidth of 32 nm between 1538 and 1570 nm, with an average optical power 20 dB above the nearby frequencies was generated. The lasers in the comb had an OSNR of 20 dB and a wavelength spacing of 0.08 nm. The results for the counter-propagating configuration were observed to have better quality.

Martins, H.; Marques, M. B.; Frazão, O.

2011-11-01

281

A wavelength-tunable fiber laser based on a twin-core fiber comb filter  

NASA Astrophysics Data System (ADS)

A wavelength-tunable fiber laser based on a twin-core fiber (TCF) comb filter is proposed and demonstrated. The TCF comb filter is fabricated by splicing a 0.85 m long TCF between two standard single mode fibers (SMFs) and with exhibits a good linear strain characteristic with a sensitivity of 1.23 pm/??. The wavelength of the laser can be linearly tuned from 1558.04 nm to 1553.62 nm by applying an axial strain to the TCF comb filter. The optical signal-to-noise ratio (OSNR) of the fiber laser reaches 45 dB. The 3 dB bandwidth is 0.02 nm. The fluctuation of the laser peak in the output power and the wavelength is less than 0.5 dB and within 0.05 nm, respectively. The fiber laser has the advantages of having a simple structure and stable operation under room temperature.

Zou, Hui; Lou, Shuqin; Yin, Guolu

2013-02-01

282

A Novel Comb Architecture for Enhancing the Sensitivity of Bulk Mode Gyroscopes  

PubMed Central

This work introduces a novel architecture for increasing the sensitivity of bulk mode gyroscopes. It is based on adding parallel plate comb drives to the points of maximum vibration amplitude, and tuning the stiffness of the combs. This increases the drive strength and results in a significant sensitivity improvement. The architecture is targeted for technologies with ?100 nm transducer gaps in order to achieve very high performance devices. In this work, this sensitivity enhancement concept was implemented in SOIMUMPs, a commercial relatively large gap technology. Prototypes were measured to operate at frequencies of ?1.5 MHz, with quality factors of ?33,000, at a 10 mTorr vacuum level. Measurements using discrete electronics show a rate sensitivity of 0.31 ?V/°/s, corresponding to a capacitance sensitivity of 0.43 aF/°/s/electrode, two orders of magnitude higher than a similar design without combs, fabricated in the same technology.

Elsayed, Mohannad Y.; Nabki, Frederic; El-Gamal, Mourad N.

2013-01-01

283

Comb-based radiofrequency photonic filters with rapid tunability and high selectivity  

NASA Astrophysics Data System (ADS)

Photonic technologies have received considerable attention regarding the enhancement of radiofrequency electrical systems, including high-frequency analogue signal transmission, control of phased arrays, analog-to-digital conversion and signal processing. Although the potential of radiofrequency photonics for the implementation of tunable electrical filters over broad radiofrequency bandwidths has been much discussed, the realization of programmable filters with highly selective filter lineshapes and rapid reconfigurability has faced significant challenges. A new approach for radiofrequency photonic filters based on frequency combs offers a potential route to simultaneous high stopband attenuation, fast tunability and bandwidth reconfiguration. In one configuration, tuning of the radiofrequency passband frequency is demonstrated with unprecedented (~40 ns) speed by controlling the optical delay between combs. In a second, fixed filter configuration, cascaded four-wave mixing simultaneously broadens and smoothes the comb spectra, resulting in Gaussian radiofrequency filter lineshapes exhibiting an extremely high (>60 dB) main lobe to sidelobe suppression ratio and (>70 dB) stopband attenuation.

Supradeepa, V. R.; Long, Christopher M.; Wu, Rui; Ferdous, Fahmida; Hamidi, Ehsan; Leaird, Daniel E.; Weiner, Andrew M.

2012-03-01

284

Evaluating the performance of the NPL femtosecond frequency combs: agreement at the 10?21 level  

NASA Astrophysics Data System (ADS)

Results are presented from a series of comparisons between two independent femtosecond frequency comb systems at NPL, which were carried out in order to assess their systematic uncertainty. Simultaneous measurements with the two systems demonstrate agreement at the level of 5 × 10?18 when measuring an optical frequency against a common microwave reference. When simultaneously measuring the ratio of two optical frequencies, agreement at the 3 × 10?21 level is observed. The results represent the highest reported level of agreement to date between Ti:Sapphire and Er-doped femtosecond combs. The limitations of the combs when operating in these two different manners are discussed, including traceability to the SI second, which can be achieved with an uncertainty below 1 × 10?16. The technical details presented underpin recent absolute frequency measurements of the 88Sr+ and 171Yb+ optical clock transitions at NPL, as well as a frequency ratio measurement between the two optical clock transitions in 171Yb+.

Johnson, L. A. M.; Gill, P.; Margolis, H. S.

2015-02-01

285

Frustrated crystallisation and hierarchical self-assembly behaviour of comb-like polymers.  

PubMed

Comb-like polymers with flexible side chains chemically pended onto a polymeric backbone afford some unusual properties due to their hierarchical structures, such as nanoscale confined crystallisation, phase transition and conformational variations, length scale effects, etc. Considerable attention has been paid to these featured polymers, regarding their importance in understanding the correlation between hierarchical structure and the assembled morphologies. In this review, we reviewed the recent research progress on the structure-property correlations of comb-like polymers. This article brings together and highlights the fabrication, structure determination and morphology characterization for comb-like polymers, especially for nanostructured packing patterns and frustrated mobility of chain segments from the selected examples. PMID:23243663

Shi, Haifeng; Zhao, Ying; Dong, Xia; Zhou, Yong; Wang, Dujin

2013-03-01

286

Demonstration of a Near-IR Laser Comb for Precision Radial Velocity Measurements in Astronomy  

E-print Network

We describe a successful effort to produce a laser comb around 1.55 $\\mu$m in the astronomical H band using a method based on a line-referenced, electro-optical-modulation frequency comb. We discuss the experimental setup, laboratory results, and proof of concept demonstrations at the NASA Infrared Telescope Facility (IRTF) and the Keck-II telescope. The laser comb has a demonstrated stability of $<$ 200 kHz, corresponding to a Doppler precision of ~0.3 m/s. This technology, when coupled with a high spectral resolution spectrograph, offers the promise of $<$1 m/s radial velocity precision suitable for the detection of Earth-sized planets in the habitable zones of cool M-type stars.

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

2015-01-01

287

Quantum teleportation in space and frequency using entangled pairs of photons from a frequency comb  

NASA Astrophysics Data System (ADS)

Using entangled pairs of photons from a frequency comb and wide-band frequency-resolved homodyne detection, we propose a sequential quantum teleportation protocol for continuous variables that teleports an unknown state in space and frequency. A subthreshold optical parametric oscillator (OPO) produces a comb of entangled pairs of photons separated by the free spectral range of the OPO cavity. Wide-band frequency-resolved homodyne detection enables direct access to the sum and difference of quadratures between different teeth in the comb. Such measurements are Einstein-Podolsky-Rosen nullifiers, and can be used as the basis for teleportation protocols. Our protocol for space-and-frequency teleportation effectively links arbitrary frequency channels for frequency-division multiplexing, which has applications in universal quantum computation and large-capacity quantum communication.

Song, Hongbin; Yonezawa, Hidehiro; Kuntz, Katanya B.; Heurs, Michele; Huntington, Elanor H.

2014-10-01

288

Mid-infrared frequency comb generation in coupled silicon microring resonators  

NASA Astrophysics Data System (ADS)

We propose and simulate an on-chip mid-IR frequency comb generator based on the four-wave mixing (FWM) effect in a coupled silicon microring resonator. The resonator is formed by suspended ridge waveguides that are designed to have low group-velocity dispersion. A continuous-wave pump laser coupled into the resonator excites other longitudinal modes of the resonator through FWM-based parametric oscillations. In comparison with the device based on a single-ring resonator, we numerically demonstrate that the pump threshold can be dramatically reduced by introducing an auxiliary ring resonator to compensate the phase mismatch between the pump and the generated comb components. The proposed frequency comb generator has a low pump threshold of ~40 mW and a high efficiency of ~25% at the pump power of 100 mW.

Zhang, Xuezhi; Liu, Tiegen; Jiang, Junfeng; Feng, Ming; Liu, Kun

2014-12-01

289

Doppler cooling with coherent trains of laser pulses and a tunable velocity comb  

SciTech Connect

We explore the possibility of decelerating and Doppler cooling an ensemble of two-level atoms by a coherent train of short, nonoverlapping laser pulses. We derive analytical expressions for mechanical force exerted by the train. In frequency space the force pattern reflects the underlying frequency comb structure. The pattern depends strongly on the ratio of the atomic lifetime to the repetition time between the pulses and pulse area. For example, in the limit of short lifetimes, the frequency-space peaks of the optical force wash out. We propose to tune the carrier-envelope offset frequency to follow the Doppler-shifted detuning as atoms decelerate; this leads to compression of atomic velocity distribution about comb teeth and results in a ''velocity comb''--a series of narrow equidistant peaks in the velocity space.

Ilinova, Ekaterina; Ahmad, Mahmoud; Derevianko, Andrei [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States)

2011-09-15

290

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

E-print Network

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 are formally assessed by calculating the 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.

Duill, Sean P O; Zhou, Rui; Barry, Liam P

2015-01-01

291

Green, red and IR frequency comb line generation from single IR pump in AlN microring resonator  

E-print Network

On-chip frequency comb generations enable compact broadband sources for spectroscopic sensing and precision spectroscopy. Recent microcomb studies focus on infrared spectral regime and have difficulty in accessing visible regime. Here, we demonstrate comb-like visible frequency line generation through second, third harmonic, and sum frequency conversion of a Kerr comb within a high Q aluminum nitride microring resonator pumped by a single telecom laser. The strong power enhancement, in conjunction with the unique combination of Pockels and Kerr optical nonlinearity of aluminum nitride, leads to cascaded frequency conversions in the visible spectrum. High-resolution spectroscopic study of the visible frequency lines indicates matched free spectrum range over all the bands. This frequency doubling and tripling effect in a single microcomb structure offers great potential for comb spectroscopy and self-referencing comb.

Jung, Hojoong; Guo, Xiang; Fischer, Debra; Tang, Hong X

2014-01-01

292

Sex education in Portugal.  

PubMed

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 Catholic Church. As in 1973, committees were formed but no action was taken. Sex education activity increased nonetheless - the first FPA document on school education prepared. In 1986 Personal and Social Education was approved by parliament providing an alternative (due to the Catholic Church) to Religious Education, but even with FPA support documents, the implementation did not begin until the end of 1990. In brief the FPA's emphasis was on the body, sexuality, sex and interpersonal relationships, and sexual reproduction. The role of FPA continues at the grass roots level in stimulating discussion; cooperating with schools, students and parents; and acting as a resource center. PMID:12343180

Frade, A; Vilar, D

1991-05-01

293

Biased diffusion in three-dimensional comb-like structures.  

PubMed

In this paper, we study biased diffusion of point Brownian particles in a three-dimensional comb-like structure formed by a main cylindrical tube with identical periodic cylindrical dead ends. It is assumed that the dead ends are thin cylinders whose radius is much smaller than both the radius of the main tube and the distance between neighboring dead ends. It is also assumed that in the main tube, the particle, in addition to its regular diffusion, moves with a uniform constant drift velocity. For such a system, we develop a formalism that allows us to derive analytical expressions for the Laplace transforms of the first two moments of the particle displacement along the main tube axis. Inverting these Laplace transforms numerically, one can find the time dependences of the two moments for arbitrary values of both the drift velocity and the dead-end length, including the limiting case of infinitely long dead ends, where the unbiased diffusion becomes anomalous at sufficiently long times. The expressions for the Laplace transforms are used to find the effective drift velocity and diffusivity of the particle as functions of its drift velocity in the main tube and the tube geometric parameters. As might be expected from common-sense arguments, the effective drift velocity monotonically decreases from the initial drift velocity to zero as the dead-end length increases from zero to infinity. The effective diffusivity is a more complex, non-monotonic function of the dead-end length. As this length increases from zero to infinity, the effective diffusivity first decreases, reaches a minimum, and then increases approaching a plateau value which is proportional to the square of the particle drift velocity in the main tube. PMID:25854222

Berezhkovskii, Alexander M; Dagdug, Leonardo; Bezrukov, Sergey M

2015-04-01

294

Mechanisms behind the metabolic flexibility of an invasive comb jelly  

NASA Astrophysics Data System (ADS)

Mnemiopsis leidyi is an invasive comb jelly which 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 between blooms and how it can bloom so fast is to study how the metabolism of this species actually responds to environmental changes in food and temperature over its different life-stages. To this end we combined modelling and data analysis to study the energy budget of M. leidyi over its full life-cycle using Dynamic Energy Budget (DEB) theory and literature data. An analysis of data obtained at temperatures ranging from 8 to 30 °C suggests that the optimum thermal tolerance range of M. leidyi is higher than 12 °C. Furthermore M. leidyi seems to undergo a so-called metabolic acceleration after hatching. Intriguingly, the onset of the acceleration appears to be delayed and the data do not yet exist which allows determining what actually triggers it. It is hypothesised that this delay confers a lot of metabolic flexibility by controlling generation time. We compared the DEB model parameters for this species with those of another holoplanktonic gelatinous zooplankton species (Pelagia noctiluca). After accounting for differences in water content, the comparison shows just how fundamentally different the two energy allocation strategies are. P. noctiluca has an extremely high reserve capacity, low turnover times of reserve compounds and high resistance to shrinking. M. leidyi adopts the opposite strategy: it has a low reserve capacity, high turnover rates of reserve compounds and fast shrinking.

Augustine, Starrlight; Jaspers, Cornelia; Kooijman, Sebastiaan A. L. M.; Carlotti, François; Poggiale, Jean-Christophe; Freitas, Vânia; van der Veer, Henk; van Walraven, Lodewijk

2014-11-01

295

Optical under-sampling by using a broadband optical comb with a high average power.  

PubMed

We demonstrate a new method to improve the performance of photonic assisted analog to digital converters (ADCs) that are based on frequency down-conversion obtained by optical under-sampling. The under-sampling is performed by multiplying the radio frequency signal by ultra-low jitter broadband phase-locked optical comb. The comb wave intensity has a smooth periodic function in the time domain rather than a train of short pulses that is currently used in most photonic assisted ADCs. Hence, the signal energy at the photo-detector output can be increased and the signal to noise ratio of the system might be improved without decreasing its bandwidth. We have experimentally demonstrated a system for electro-optical under-sampling with a 6-dB bandwidth of 38.5 GHz and a spur free dynamic range of 99 dB/Hz(2/3) for a signal with a carrier frequency of 35.8 GHz, compared with 94 dB/Hz(2/3) for a signal at 6.2 GHz that was obtained in the same system when a pulsed optical source was used. The optical comb was generated by mixing signals from two dielectric resonator oscillators in a Mach-Zehnder modulator. The comb spacing is equal to 4 GHz and its bandwidth was greater than 48 GHz. The temporal jitter of the comb measured by integrating the phase noise in a frequency region of 10 kHz to 10 MHz around comb frequencies of 16 and 20 GHz was only about 15 and 11 fs, respectively. PMID:24977809

Sherman, Alexander; Horowitz, Moshe; Zach, Shlomo

2014-06-30

296

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

NASA Astrophysics Data System (ADS)

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 ?m. 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 300 cm^{-1} , giving an instrumental resolution of 0.4 cm^{-1} . 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 ?m, 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 350 cm^{-1} . This special cavity design allows the spectral resolution to be improved to 0.2 cm^{-1} without locking the OPO cavity, indicating that this OPO represents an ideal high-power broadband mid-infrared source for real-time gas sensing.

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

2015-02-01

297

Comb-like oligoaminoethane carriers: change in topology improves pDNA delivery.  

PubMed

Establishing precise structure-activity relationships is important for the optimization of synthetic carriers for gene delivery. Sequence-defined oligomers with branched or linear shapes were synthesized to investigate the influence of topology on their biophysical properties and biological performance. Comb-like structures were synthesized consisting of an oligolysine peptide backbone modified at the ?-amino groups with four different artificial oligoamino acids, succinyl-diethylene triamine (Sdt), succinyl-triethylene tetramine (Stt), succinyl-tetraethylene pentamine (Stp), and succinyl-pentaethylene hexamine (Sph). Optionally the amino acids histidine and alanine were inserted into the oligolysine backbone to assess a possible buffer or spacer effect. After the evaluation of biophysical properties, the best performing oligomers, containing the Stp or Sph building blocks, were compared to corresponding linear oligomers where Stp or Sph are directly integrated into the linear oligolysine row. Clear differences between the comb and linear carriers were observed in the comparison of properties such as DNA complexation ability, buffer capacity, cellular association and internalization, and gene transfer. For the Stp containing structures, the comb topology mediated an increased buffer capacity at endosomal pH. For the Sph containing structures, in sharp contrast, the linear topology displayed advantageous endosomal buffering. Interestingly, for both Stp and Sph carriers, the comb in comparison to the linear topologies mediated a higher overall cellular uptake despite a lower cell association. For Stp combs, the combined advantage in both buffering and cellular uptake resulted in a strong (10- to >100-fold) increase in DNA transfection efficiency. In the case of Sph carriers, comb topology mediated only moderately (maximum 4-fold) enhanced gene transfer over the linear topology. PMID:24359105

Scholz, Claudia; Kos, Petra; Wagner, Ernst

2014-02-19

298

Symbiotic Fungi Produce Laccases Potentially Involved in Phenol Degradation in Fungus Combs of Fungus-Growing Termites in Thailand†  

PubMed Central

Fungus-growing termites efficiently decompose plant litter through their symbiotic relationship with basidiomycete fungi of the genus Termitomyces. Here, we investigated phenol-oxidizing enzymes in symbiotic fungi and fungus combs (a substrate used to cultivate symbiotic fungi) from termites belonging to the genera Macrotermes, Odontotermes, and Microtermes in Thailand, because these enzymes are potentially involved in the degradation of phenolic compounds during fungus comb aging. Laccase activity was detected in all the fungus combs examined as well as in the culture supernatants of isolated symbiotic fungi. Conversely, no peroxidase activity was detected in any of the fungus combs or the symbiotic fungal cultures. The laccase cDNA fragments were amplified directly from RNA extracted from fungus combs of five termite species and a fungal isolate using degenerate primers targeting conserved copper binding domains of basidiomycete laccases, resulting in a total of 13 putative laccase cDNA sequences being identified. The full-length sequences of the laccase cDNA and the corresponding gene, lcc1-2, were identified from the fungus comb of Macrotermes gilvus and a Termitomyces strain isolated from the same fungus comb, respectively. Partial purification of laccase from the fungus comb showed that the lcc1-2 gene product was a dominant laccase in the fungus comb. These findings indicate that the symbiotic fungus secretes laccase to the fungus comb. In addition to laccase, we report novel genes that showed a significant similarity with fungal laccases, but the gene product lacked laccase activity. Interestingly, these genes were highly expressed in symbiotic fungi of all the termite hosts examined. PMID:16332742

Taprab, Yaovapa; Johjima, Toru; Maeda, Yoshimasa; Moriya, Shigeharu; Trakulnaleamsai, Savitr; Noparatnaraporn, Napavarn; Ohkuma, Moriya; Kudo, Toshiaki

2005-01-01

299

Coherent frequency combs produced by self frequency modulation in quantum cascade lasers  

NASA Astrophysics Data System (ADS)

One salient characteristic of Quantum Cascade Laser (QCL) is its very short ? ˜ 1 ps gain recovery time that so far thwarted the attempts to achieve self-mode locking of the device into a train of single pulses. We show theoretically that four wave mixing, combined with the short gain recovery time causes QCL to operate in the self-frequency-modulated regime characterized by a constant power in time domain and stable coherent comb in the frequency domain. Coherent frequency comb may enable many potential applications of QCL's in sensing and measurement.

Khurgin, J. B.; Dikmelik, Y.; Hugi, A.; Faist, J.

2014-02-01

300

Direct link of a mid-infrared QCL to a frequency comb by optical injection.  

PubMed

A narrow-linewidth comb-linked nonlinear source is used as master radiation to injection lock a room-temperature mid-infrared quantum cascade laser (QCL). This process leads to a direct lock of the QCL to the optical frequency comb, providing the unique features of narrow linewidth, absolute frequency, higher output power, and wide mode-hop-free tunability. The QCL reproduces the injected radiation within more than 94%, with a reduction of the frequency-noise spectral density by 3 to 4 orders of magnitude up to about 100 kHz, and a linewidth narrowing from a few MHz to 20 kHz. PMID:22446207

Borri, S; Galli, I; Cappelli, F; Bismuto, A; Bartalini, S; Cancio, P; Giusfredi, G; Mazzotti, D; Faist, J; De Natale, P

2012-03-15

301

Evidence for frequency comb emission from a Fabry-Pérot terahertz quantum-cascade laser.  

PubMed

We report on a broad-band terahertz quantum-cascade laser (QCL) with a long Fabry-Pérot ridge cavity, for which the tuning range of the individual laser modes exceeds the mode spacing. While a spectral range of approximately 60 GHz (2 cm(-1)) is continuously covered by current and temperature tuning, the total emission range spans more than 270 GHz (9 cm(-1)). Within certain operating ranges, we found evidence for stable frequency comb operation of the QCL. An experimental technique is presented to characterize frequency comb operation, which is based on the self-mixing effect. PMID:25606987

Wienold, M; Röben, B; Schrottke, L; Grahn, H T

2014-12-15

302

Observations of complex frequency comb structure in a harmonically-pumped femtosecond optical parametric oscillator  

NASA Astrophysics Data System (ADS)

Various schemes allow femtosecond optical parametric oscillators to produce pulses at harmonics of their pump laser repetition frequency, each apparently offering the possibility of generating widely-spaced, tunable frequency combs. Using a 100-MHz Ti:sapphire pump laser, we have compared two alternative optical parametric oscillator architectures, both leading to 300-MHz pulses but one configured in a cavity three times shorter than the pump laser and the other in a cavity one-third longer. Heterodyne measurements between the pump and each of these two systems show that they possess different carrier-envelope offset characteristics, with implications on the coherence and stabilization of the resulting combs.

McCracken, Richard A.; Balskus, Karolis; Zhang, Zhaowei; Reid, Derryck T.

2015-03-01

303

Simultaneous broadband microwave downconversion and programmable complex filtering by optical frequency comb shaping.  

PubMed

High-repetition-rate optical frequency combs can act as broadband photonic mixers and downconvert a microwave signal to an intermediate frequency (IF) band so that it becomes accessible with high-speed electronics. In this Letter, we show that with line-by-line pulse shaping and dispersive propagation, the photonic mixer can simultaneously perform programmable multitap complex-coefficient-filtering within the IF band. This solution opens new possibilities for microwave signal processing by combining the flexibility of optoelectronic frequency comb technology with high-speed analog-to-digital converters. PMID:23027256

Torres-Company, Victor; Leaird, Daniel E; Weiner, Andrew M

2012-10-01

304

Coherent frequency combs produced by self frequency modulation in quantum cascade lasers  

SciTech Connect

One salient characteristic of Quantum Cascade Laser (QCL) is its very short ????1?ps gain recovery time that so far thwarted the attempts to achieve self-mode locking of the device into a train of single pulses. We show theoretically that four wave mixing, combined with the short gain recovery time causes QCL to operate in the self-frequency-modulated regime characterized by a constant power in time domain and stable coherent comb in the frequency domain. Coherent frequency comb may enable many potential applications of QCL's in sensing and measurement.

Khurgin, J. B.; Dikmelik, Y. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Hugi, A.; Faist, J. [Institute for Quantum Electronics, ETH Zurich, Wolfgang-Pauli-Strasse 16, 8093 Zurich (Switzerland)

2014-02-24

305

Two-Wavelength Multi-Gigahertz Frequency Comb-Based Interferometry for Full-Field Profilometry  

NASA Astrophysics Data System (ADS)

The multi-gigahertz frequency comb-based interferometer exhibits only the interference amplitude peak without the phase fringes, which can produce a rapid axial scan for full-field profilometry and tomography. Despite huge technical advantages, there remain problems that the interference intensity undulations occurred depending on the interference phase. To avoid such problems, we propose a compensation technique of the interference signals using two frequency combs with slightly varied center wavelengths. The compensated full-field surface profile measurements of cover glass and onion skin were demonstrated experimentally to verify the advantages of the proposed method.

Choi, Samuel; Kashiwagi, Ken; Kojima, Shuto; Kasuya, Yosuke; Kurokawa, Takashi

2013-10-01

306

Application of Laser Frequency Combs and Nitrogen Vacancy Diamond Magnetometers to Searches for New Physics  

NASA Astrophysics Data System (ADS)

Searches for new physics often benefit from improved technologies. Here we discuss possible applications of two emerging technologies to searches for physics beyond the Standard Model. First, laser frequency combs enable broad spectral coverage and coherent conversion between optical and RF signals. We are investigating tests of the nonminimal Standard-Model Extension using frequency combs coupled to broadband optical cavities. Second, nitrogen vacancy centers in diamond enable precision nanoscale magnetometry with applications from imaging to quantum science. We are investigating their use in searches for short-range spin-spin couplings.

Phillips, D. F.; Walsworth, R. L.

2014-01-01

307

Comb/serpentine/cross-bridge test structure for fabrication process evaluation  

NASA Technical Reports Server (NTRS)

The comb/serpentine/cross-bridge structure was developed to monitor and evaluate same layer shorts and step coverage problems (open and high-resistance wire over steps) for integrated circuit fabrication processes. The cross-bridge provides local measurements of wire sheet resistance and wirewidth. These local parametric measurements are used in the analysis of the serpentine wire, which identifies step coverage problems. The comb/serpentine/cross-bridge structure was fabricated with 3 microns CMOS/bulk p-well process and tested using a computer-controlled parametric test system.

Sayah, Hoshyar R.; Buehler, Martin G.

1988-01-01

308

Optical Nyquist channel generation using a comb-based tunable optical tapped-delay-line.  

PubMed

We demonstrate optical Nyquist channel generation based on a comb-based optical tapped-delay-line. The frequency lines of an optical frequency comb are used as the taps of the optical tapped-delay-line to perform a finite-impulse response (FIR) filter function. A single optical nonlinear element is utilized to multiplex the taps and form the Nyquist signal. The tunablity of the approach over the baud rate and modulation format is shown. Optical signal-to-noise ratio penalty of 2.8 dB is measured for the 11-tap Nyquist filtering of 32-Gbaud QPSK signal. PMID:25490627

Ziyadi, Morteza; Chitgarha, Mohammad Reza; Mohajerin-Ariaei, Amirhossein; Khaleghi, Salman; Almaiman, Ahmed; Cao, Yinwen; Willner, Moshe J; Tur, Moshe; Paraschis, Loukas; Langrock, Carsten; Fejer, Martin M; Touch, Joseph D; Willner, Alan E

2014-12-01

309

Optical properties of the iridescent organ of the comb-jellyfish Beroë cucumis (Ctenophora)  

NASA Astrophysics Data System (ADS)

Using transmission electron microscopy, analytical modeling, and detailed numerical simulations, the iridescence observed from the comb rows of the ctenophore Beroë cucumis was investigated. It is shown that the changing coloration which accompanies the beating of comb rows as the animal swims can be explained by the weakly-contrasted structure of the refractive index induced by the very coherent packing of locomotory cilia. The colors arising from the narrow band-gap reflection are shown to be highly saturated and, as a function of the incidence angle, cover a wide range of the visible and ultraviolet spectrum. The high transparency of the structure at the maximal bioluminescence wavelength is also explained.

Welch, Victoria; Vigneron, Jean Pol; Lousse, Virginie; Parker, Andrew

2006-04-01

310

High-resolution terahertz spectroscopy with a single tunable frequency comb.  

PubMed

We report an improvement of three orders of magnitude in the spectral resolution of a recently proposed single-comb terahertz spectroscopy [Opt. Lett.39, 5669 (2014)]. The improvement is achieved by using a femtosecond optical pulse train with a tunable repetition rate. Terahertz comb with tunable spectral line spacing generated by the train is detected via nonlinear mixing with a harmonic of a CW signal from a microwave frequency synthesizer. By applying this technique to the low-pressure gas spectroscopy, we achieved a 100 kHz spectral resolution in measuring separate absorption lines of the rotational manifold of fluoroform (CF3H). PMID:25607192

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

2014-12-29

311

Radiative effects driven by shock waves in cavity-less four-wave mixing combs.  

PubMed

We investigate the frequency comb spectrum produced in an optical fiber via multiple four-wave mixing pumped in the normal group-velocity region close to the zero-dispersion wavelength. We show that the dynamics are strongly affected by shock formation. In this regime, the resonant radiation emitted by the shock waves correctly explains the enhanced spectral peaks in the comb. The resonant frequencies found by means of perturbation theory accurately fit those observed from the numerical simulation based on the generalized nonlinear Schrödinger equation. PMID:25360978

Conforti, Matteo; Trillo, Stefano

2014-10-01

312

Doing Gender in Sex and Sex Research  

Microsoft Academic Search

Gender is central to sexuality, and vice versa, but there are a number of difficulties with the treatment of gender in sex\\u000a research. Apparently, it is hard to find a balance between two conflicting needs. First, obviously, it is necessary to make\\u000a distinctions between women and men, for political as well as research-technical and theoretical reasons. A second requirement,\\u000a at

Ine Vanwesenbeeck

2009-01-01

313

Sex education in Czechoslovakia.  

PubMed

The Czechoslovak FPA (SPRVR) established in 1979 as a separate agency intends to maintain contact with the Ministry of Education in order to strengthen the position of parenthood education and influence the preparation of guidelines. The compulsory school system includes 6 to 15 year olds. After 1948, the head of the school determined the role of sex education and had the option of inviting a guest lecturer. In 1956, the Ministry of Education ruled that 1 sex education lecture was required for 14 year olds. In 1972, Government decision N137 required family life education at all school levels: pre-school stage, basic grades, secondary and higher education, and universities in preparation for harmonious, stable family life, parentship, and parenthood. In 1987, the new Minister of Education changed the prior policy of a separate secondary school subject to integration in other subjects. Due to this policy, there is great variation among schools, regions and teachers. Some emphasize the negative consequences of sex; personal experience and shame are also involved. Textbooks and materials are not uniform, and SPRVR is attempting to develop the resources to prepare sex materials and train unknowledgeable teachers. The Institute of Sexology since 1921 with its small staff has prepared texts and lecture notes and has a teaching staff but cannot meet the needs of the entire school population. New trends in sex education has emphasized the positive side of sex, behavior, and health, but have been met with parent and teacher apprehension and disagreement because of the mortality or the promotion of sex and a liberal attitude toward abortion. SPRVR holds scientific meetings on parenthood education with an interdisciplinary approach. There has been little consensus or uniformity of action, and inadequate sexual knowledge of teachers attitudes. The parenthood program also faces the influence of the Catholic Church which would like to abolish sex education. PMID:12343169

Buresova, A

1991-05-01

314

Exposing Sex Stereotypes in Recent Same-Sex Marriage Jurisprudence  

Microsoft Academic Search

This article examines sex discrimination arguments in recent same-sex marriage cases. Since 1993, when the Hawaii Supreme Court held in Baehr v. Lewin that denying same-sex couples the right to marry could state a claim of sex discrimination, every state high court to consider the issue has rejected the claim. But many recent decisions have in fact relied upon sex-based

Deborah A. Widiss; Elizabeth Rosenblatt; Douglas NeJaime

2007-01-01

315

Why sex matters for neuroscience  

Microsoft Academic Search

A rapidly burgeoning literature documents copious sex influences on brain anatomy, chemistry and function. This article highlights some of the more intriguing recent discoveries and their implications. Consideration of the effects of sex can help to explain seemingly contradictory findings. Research into sex influences is mandatory to fully understand a host of brain disorders with sex differences in their incidence

Larry Cahill

2006-01-01

316

"Sex Health" Deaf Health Talks,  

E-print Network

relationship Sex is enjoyable Sex is safe It is never forced It is never abused or violent Picture: newsinfo"Sex Health" Deaf Health Talks, March 17, 2011 #12;Supporters Deaf Health Community Committee.iu.edu #12;Health Benefits of Good and Regular (Safer) Sex Reduces stress Improves immune system Burns

Goldman, Steven A.

317

Odontometric sex assessment in Indians  

Microsoft Academic Search

Sex determination of unidentified skeletal remains is important and various hard-tissue parameters have been evaluated towards this end. The dentition is considered as a useful adjunct in skeletal sex determination, particularly since teeth are resistant to postmortem destruction and fragmentation. Sex dimorphism in tooth size and the accuracy of odontometric sex prediction, is found to vary in different regions and

Sudeendra Prabhu; Ashith B. Acharya

2009-01-01

318

Reclassification of Bacteriovorax marinus as Halobacteriovorax marinus gen. nov., comb. nov. and Bacteriovorax litoralis as Halobacteriovorax litoralis comb. nov.; description of Halobacteriovoraceae fam. nov. in the class Deltaproteobacteria.  

PubMed

The taxonomic status of saltwater Bdellovibrio-like prokaryotic predators has been revised to assign species to Halobacteriovorax gen. nov. A reclassification of Bacteriovorax marinus as Halobacteriovorax marinus comb. nov. (type strain ATCC BAA-682(T)?=?DSM 15412(T)) and Bacteriovorax litoralis as Halobacteriovorax litoralis comb. nov. (type strain ATCC BAA-684(T)?=?DSM 15409(T)) is proposed. This revision is necessary because a previous proposal to retain saltwater isolates as species of Bacteriovorax and reclassify Bacteriovorax stolpii as Bacteriolyticum stolpii was not approved. The type species of a genus cannot be reassigned to another genus. Bacteriovorax stolpii is thus retained as the type species of Bacteriovorax and Halobacteriovorax marinus is the type species of Halobacteriovorax and of Halobacteriovoraceae fam. nov. PMID:25406234

Koval, Susan F; Williams, Henry N; Stine, O Colin

2015-02-01

319

AIDS and sex tourism.  

PubMed

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. PMID:12286016

Herold, E S; Van Kerkwijk, C

1992-01-01

320

Copy Number Variation in Intron 1 of SOX5 Causes the Pea-comb Phenotype in Chickens  

PubMed Central

Pea-comb is a dominant mutation in chickens that drastically reduces the size of the comb and wattles. It is an adaptive trait in cold climates as it reduces heat loss and makes the chicken less susceptible to frost lesions. Here we report that Pea-comb is caused by a massive amplification of a duplicated sequence located near evolutionary conserved non-coding sequences in intron 1 of the gene encoding the SOX5 transcription factor. This must be the causative mutation since all other polymorphisms associated with the Pea-comb allele were excluded by genetic analysis. SOX5 controls cell fate and differentiation and is essential for skeletal development, chondrocyte differentiation, and extracellular matrix production. Immunostaining in early embryos demonstrated that Pea-comb is associated with ectopic expression of SOX5 in mesenchymal cells located just beneath the surface ectoderm where the comb and wattles will subsequently develop. The results imply that the duplication expansion interferes with the regulation of SOX5 expression during the differentiation of cells crucial for the development of comb and wattles. The study provides novel insight into the nature of mutations that contribute to phenotypic evolution and is the first description of a spontaneous and fully viable mutation in this developmentally important gene. PMID:19521496

Wright, Dominic; Boije, Henrik; Meadows, Jennifer R. S.; Bed'hom, Bertrand; Gourichon, David; Vieaud, Agathe; Tixier-Boichard, Michèle; Rubin, Carl-Johan; Imsland, Freyja; Hallböök, Finn; Andersson, Leif

2009-01-01

321

A 12.5 GHz-spaced optical frequency comb spanning >400 nm for near-infrared astronomical spectrograph calibration  

SciTech Connect

A 12.5 GHz-spaced optical frequency comb locked to a global positioning system disciplined oscillator for near-infrared (IR) spectrograph calibration is presented. The comb is generated via filtering a 250 MHz-spaced comb. Subsequent nonlinear broadening of the 12.5 GHz comb extends the wavelength range to cover 1380-1820 nm, providing complete coverage over the H-band transmission window of earth's atmosphere. Finite suppression of spurious sidemodes, optical linewidth, and instability of the comb has been examined to estimate potential wavelength biases in spectrograph calibration. Sidemode suppression varies between 20 and 45 dB, and the optical linewidth is {approx}350 kHz at 1550 nm. The comb frequency uncertainty is bounded by {+-}30 kHz (corresponding to a radial velocity of {+-}5 cm/s), limited by the global positioning system disciplined oscillator reference. These results indicate that this comb can readily support radial velocity measurements below 1 m/s in the near IR.

Quinlan, F.; Diddams, S. A. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States); Ycas, G. [National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305 (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States); Osterman, S. [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, Colorado 80309 (United States)

2010-06-15

322

Scalable and reconfigurable generation of flat optical comb for WDM-based next-generation broadband optical access networks  

NASA Astrophysics Data System (ADS)

A tunable comb generator (TCG) by cascading a single phase modulator (PM) with two identical intensity modulators (IMs) is proposed for the scalable and reconfigurable generation of flat optical comb. Detailed theoretical analysis is performed to find out the optimized condition for flat optical comb generation using the proposed TCG and the scalability of the generated optical comb is also analyzed under the optimized condition. An experiment is conducted to verify the feasibility of the TCG and the experimental results agree well with the theoretical prediction. The reconfigurability and stability of the obtained optical comb are discussed as well in the experiment. After that, the obtained optical comb is utilized as the optical source for a wavelength-division multiplexed radio-over-fiber (WDM-RoF) system and a hybrid WDM orthogonal frequency-division multiple access passive optical network (WDM-OFDMA-PON). Two corresponding experimental demonstrations are presented to verify the feasibility of employing the obtained flat optical comb as the WDM optical source, respectively. In the WDM-RoF system, 17 WDM channels each carrying 16×5 Gb/s non-return-to-zero (NRZ) data have been up-converted to 10 GHz simultaneously. In the hybrid WDM-OFDMA-PON, 17-channel OFDM-WDM double-sideband (DSB) signal achieving 10.85 Gb/s traffic per channel is successfully transmitted for both wired baseband OFDM access and wireless 10 GHz OFDM access.

Chen, Chen; Zhang, Chongfu; Zhang, Wei; Jin, Wei; Qiu, Kun

2014-06-01

323

Sex and Gender Similarities and Differences in Communication Values in Same-Sex and Cross-Sex Friendships  

Microsoft Academic Search

This study extends research on sex differences and similarities in communication values by examining (a) the influence of sex of friend on ratings of functional communication skills in same-sex and cross-sex friendships, (b) the moderating role of friend's sex in sex differences in evaluations, and (c) the mediating role of psychological gender in sex differences in communication values. Participants (144

Amanda J. Holmstrom

2009-01-01

324

Self-organizing pattern formation on the combs of honey bee colonies  

Microsoft Academic Search

Summary A characteristic pattern of brood, pollen, and honey develops on the combs of a honey bee colony, consisting of three distinct concentric regions — a central brood area, a surrounding rim of pollen, and a large peripheral region of honey. That the pattern is consistent and well-organized suggests its adaptive value for the colony, yet the mechanism of pattern

Scott Camazine

1991-01-01

325

Optical antenna of comb-shaped split ring architecture for increased field localization in  

E-print Network

designs of optical antennas based on comb-shaped split ring architecture that display multi resonance. Photonics 5(2), 83­90 (2011). 6. K.-S. Lee and M. A. El-Sayed, "Gold and silver nanoparticles in sensing individual Ag nanoparticles and particle pairs," Appl. Phys. Lett. 80(10), 1826­1828 (2002). 11. R. M. Bakker

Demir, Hilmi Volkan

326

Hexagonal comb cells of honeybees are not produced via a liquid equilibrium process  

NASA Astrophysics Data System (ADS)

The nests of European honeybees ( Apis mellifera) are organised into wax combs that contain many cells with a hexagonal structure. Many previous studies on comb-building behaviour have been made in order to understand how bees produce this geometrical structure; however, it still remains a mystery. Direct construction of hexagons by bees was suggested previously, while a recent hypothesis postulated the self-organised construction of hexagonal comb cell arrays; however, infrared and thermographic video observations of comb building in the present study failed to support the self-organisation hypothesis because bees were shown to be engaged in direct construction. Bees used their antennae, mandibles and legs in a regular sequence to manipulate the wax, while some bees supported their work by actively warming the wax. During the construction of hexagonal cells, the wax temperature was between 33.6 and 37.6 °C. This is well below 40 °C, i.e. the temperature at which wax is assumed to exist in the liquid equilibrium that is essential for self-organised building.

Bauer, Daniel; Bienefeld, Kaspar

2013-01-01

327

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

ERIC Educational Resources Information Center

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…

McPherson, Robert S.

2010-01-01

328

Digital approach to stabilizing optical frequency combs and beat notes of CW lasers  

NASA Astrophysics Data System (ADS)

In cases when it is necessary to lock optical frequencies generated by an optical frequency comb to a precise radio frequency (RF) standard (GPS-disciplined oscillator, H-maser, etc.) the usual practice is to implement phase and frequency-locked loops. Such system takes the signal generated by the RF standard (usually 10 MHz or 100 MHz) as a reference and stabilizes the repetition and offset frequencies of the comb contained in the RF output of the f-2f interferometer. These control loops are usually built around analog electronic circuits processing the output signals from photo detectors. This results in transferring the stability of the standard from RF to optical frequency domain. The presented work describes a different approach based on digital signal processing and software-defined radio algorithms used for processing the f-2f and beat-note signals. Several applications of digital phase and frequency locks to a RF standard are demonstrated: the repetition (frep) and offset frequency (fceo) of the comb, and the frequency of the beat note between a CW laser source and a single component of the optical frequency comb spectrum.

?ížek, Martin; ?íp, Ond?ej; Å míd, Radek; Hrabina, Jan; Mikel, B?etislav; Lazar, Josef

2013-10-01

329

Measuring the shift of a femtosecond laser frequency comb by the interference method  

SciTech Connect

We have demonstrated the possibility of measuring the femtosecond laser frequency comb shift by the position of a Fabry - Perot interferometer's transmission bands with a statistical error of 10{sup -2} and a systematic shift of 10{sup -1}. (control of laser radiation parameters)

Basnak, Dmitriy V; Bikmukhametov, K A; Dmitriev, Aleksandr K; Dychkov, Aleksandr S; Kuznetsov, Sergei A; Lugovoy, A A; Mitsziti, P

2012-01-31

330

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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...

331

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

E-print Network

Small-cell comb does not control Varroa mites in colonies of honeybees of European origin Thomas D size 1. INTRODUCTION The mite Varroa destructor is a new parasite of European honeybees living in North of European honeybees does not receive mite control treatments, the mite popula- tion will grow from just

332

Gravity orientation in social wasp comb cells (Vespinae) and the possible role of embedded minerals  

NASA Astrophysics Data System (ADS)

Social wasps and hornets maintain their nest in the dark. The building of the combs by all Vespinae is always in the direction of the gravitational force of Earth, and in each cell’s ceiling, at least one ‘keystone’ is embedded and fastened by saliva. The sensory mechanisms that enable both building of sizeable symmetrical combs and nursing of the brood in the darkness merit investigation, and the aim of the present study was to identify and characterize the ‘keystones’ that exist in the ceiling and in the walls of the social wasp comb cells. Bio-ferrography was used to isolate magnetic particles on slides. These slides, as well as original cells, were analyzed in an environmental scanning electron microscope by a variety of analytical tools. It was found that both the roof and the walls of each comb cell bear minerals, like ferrites, as well as Ti and Zr. The latter two elements are less abundant in the soil around the nest. Ti and Zr are known to reflect infrared (IR) light. IR imaging showed a thermoregulatory center in the dorsal thorax of the adult Oriental hornet. It is not known yet whether these insects can sense IR light.

Ishay, Jacob S.; Barkay, Zahava; Eliaz, Noam; Plotkin, Marian; Volynchik, Stanislav; Bergman, David J.

2008-04-01

333

Optical Fourier transform based in-plane vibration characterization for MEMS comb structure.  

PubMed

On-line and on-wafer characterizations of mechanical properties of Micro-Electro-Mechanical-System (MEMS) with efficiency are very important to the mass production of MEMS foundry in the near future. However, challenges still remain. In this paper, we present an in-plane vibration characterizing method for MEMS comb using optical Fourier transform (OFT). In the experiment, the intensity distribution at the focal plane was captured to characterize the displacement of the vibrator in the MEMS comb structure. A typical MEMS comb was tested to verify the principle. The shape and the movement of MEMS comb was imitated and tested to calibrate the measurement by using a spatial light modulator (SLM). The relative standard deviations (RSD) of the measured displacements were better than 5%, where the RSD is defined as the ratio of the standard deviation to the mean. It is convinced that the presented method is feasible for on-line and on-wafer characterizations for MEMS with great convenience, high efficiency and low cost. PMID:23482039

Gao, Yongfeng; Cao, Liangcai; You, Zheng; Zhao, Jiahao; Zhang, Zichen; Yang, Jianzhong

2013-02-25

334

Satellite and Next Generation Networks: proposal for QoS architectures Stphane Combes  

E-print Network

for IPv6 (SATIP6) [21] and ESA Integrated Resources and QoS Management in DVB-RCS networks (QoSforRCS) [111 Satellite and Next Generation Networks: proposal for QoS architectures Stéphane Combes Alcatel) Quality of Service (QoS) architecture. This paper will define NGN overall architecture, showing how

Paris-Sud XI, Université de

335

Effect of partial comb and wattle trim on pullet behavior and thermoregulation  

Technology Transfer Automated Retrieval System (TEKTRAN)

The wattles and comb of chickens are important for thermoregulation allowing for heat exchange during high temperatures. These integumentary tissues are sometimes trimmed to prevent tears if caught on cage equipment and to also improve feed efficiency; however, the procedure itself could be painful ...

336

July /August 2005 Confounding Queens Formic Acid Safety Combs Build Themselves  

E-print Network

____________________________________________________________________________________ Confounding Queens Formic Acid Safety Combs Build Themselves UK Queen Problems Percentage Ingredients Labeling performance due to Varroa infestation: reduced sperm count in drones; reduced queen mating success; reduced queens laying variable amounts of drone eggs in worker cells; 5. Good egg laying pattern, at first

Ferrara, Katherine W.

337

LARGE STROKE ELECTROSTATIC COMB-DRIVE ACTUATORS BASED ON A NOVEL FLEXURE MECHANISM  

E-print Network

rigid and all compliance comes from the flexure. Also, the in-plane rotation stiffness is assumed high National Institute of Standards and Technology, Gaithersburg, MD, USA ABSTRACT This paper presents in-plane/nano positioning [2]. A linear in-plane electrostatic comb-drive actuator, shown in Fig. 1, comprises two

Awtar, Shorya

338

Quantum theory of phase correlations in optical frequency combs generated by stimulated Raman scattering  

SciTech Connect

We explore theoretically the phase correlation between multiple generated sidebands in a Raman optical frequency comb under conditions of spontaneous initiation from quantum zero-point noise. We show that there is a near-deterministic correlation between sideband phases in each laser shot which may lead to synthesis of attosecond pulse trains.

Wu Chunbai; Raymer, M. G. [Department of Physics, Oregon Center for Optics, University of Oregon, Eugene, Oregon 97403 (United States); Wang, Y. Y.; Benabid, F. [Gas-Phase Photonic Materials Group, Centre for Photonics and Photonic Materials, University of Bath, Claverton Down, Bath, BA2 7AY (United Kingdom)

2010-11-15

339

Multitap microwave photonic filters with programmable phase response via optical frequency comb shaping  

E-print Network

, MWPFs are based on a delay-line multi- tap geometry, inspired by finite-impulse-response (FIR) digital bandwidth. Complex coefficient taps are achieved by optical line-by-line pulse shaping on a 10 GHz flat delay-line scheme involving line-by-line pulse shaping of an optical frequency comb in an interferometer

Purdue University

340

Absolute distance measurement based on femtosecond frequency comb with wavelet transform  

NASA Astrophysics Data System (ADS)

Spectrally resolved interferometry based on optical frequency comb is an effective way for absolute distance measurement. We introduce wavelet transform to spectrally resolve interferometry as an effective data analysis tool. A comparison has been presented between wavelet transform and conventional algorithm. The results demonstrate that the wavelet transform is a reliable technique and provides good performance over noise resistance for spectrally resolved interferometry measurement.

Li, Yao; Hu, Kun; Ji, Rongyi; Liu, Deming; Zhou, Weihu

2014-12-01

341

Frequency Comb Vernier Spectroscopy for Broadband, High-Resolution, High-Sensitivity Absorption and Dispersion Spectra  

Microsoft Academic Search

A femtosecond frequency comb provides a vast number of equidistantly spaced narrow band laser modes that can be simultaneously tuned and frequency calibrated with 15 digit accuracy. Our Vernier spectrometer utilizes all of theses modes in a massively parallel manner to rapidly record both absorption and dispersion spectra with a sensitivity that is provided by a high finesse broadband optical

Christoph Gohle; Björn Stein; Albert Schliesser; Thomas Udem; Theodor W. Hänsch

2007-01-01

342

Low Phase Noise 250 MHz Repetition Rate Fiber fs Laser for Frequency Comb Applications  

Microsoft Academic Search

Er3+ -doped fiber-lasers efficiently generate frequency-combs for optical frequency metrology. We have for the first time resolved the two main concerns against fiber lasers vs the well established Ti:Sa technology by increasing the repetition rate to 250 MHz and decreasing the carrier envelope offset phase noise well below 1 rad.

T. Wilken; T. W. Hansch; R. Holzwarth; P. Adel; M. Mei

2007-01-01

343

F. Combes, D. Barret and T. Contini (eds) THE GREEN VEGETATION AS A BIOSIGNATURE ON  

E-print Network

. The observer is above Central America, reproducing the Earth as seen from the Moon the day of EarthshineSF2A 2003 F. Combes, D. Barret and T. Contini (eds) THE GREEN VEGETATION AS A BIOSIGNATURE ON EARTH AND EARTH-LIKE PLANETS: POLDER DATA AND EARTHSHINE OBSERVATIONS Arnold, L.1, Br´eon, F.M.2, Brewer, S.3

Arnold, Luc

344

Torsional defects, dielectric response and dynamics of comb polymer liquid crystals  

Microsoft Academic Search

Nematically and smectically ordered teeth of comb polymers are known to be coupled to the backbone. We speculate that if suitable chemistry can make this coupling torsional as well, then dipolar correlations can be induced in addition to quadrupolar order. We then predict an activated dielectric response mirroring the creation of torsional defects in the tooth order. The susceptibility becomes

M. Warner; H. Liu

1989-01-01

345

Quantum theory of phase correlations in optical frequency combs generated by stimulated Raman scattering  

NASA Astrophysics Data System (ADS)

We explore theoretically the phase correlation between multiple generated sidebands in a Raman optical frequency comb under conditions of spontaneous initiation from quantum zero-point noise. We show that there is a near-deterministic correlation between sideband phases in each laser shot which may lead to synthesis of attosecond pulse trains.

Wu, Chunbai; Raymer, M. G.; Wang, Y. Y.; Benabid, F.

2010-11-01

346

All-Optical Signal Processing of Periodic Signals Using a Brillouin Gain Comb  

Microsoft Academic Search

The amplification of periodic signals using a Brillouin gain comb provides the opportunity to manipulate the amplitude and phase of a signal's individual spectral harmonics and, therefore, its temporal characteristics. In addition to obvious applications in pulse shaping, the approach offers new opportunities in the context of slow-light generation which include power-efficient Brillouin amplification of broadband periodic signals without delay,

CÉsar Jauregui Misas; Periklis Petropoulos; David J. Richardson

2008-01-01

347

The inverted pendulum, interface phonons and optic Tamm states Nicolas Combe  

E-print Network

The inverted pendulum, interface phonons and optic Tamm states Nicolas Combe Centre d that a parametric pendulum oscillates in the vicinity of its unstable equilibrium positions to the case of waves of an unstable equilibrium position using a parametric excita- tion (in the inverted pendulum experiment

348

The inverted pendulum, interface phonons and optic Tamm states Nicolas Combe  

E-print Network

The inverted pendulum, interface phonons and optic Tamm states Nicolas Combe Centre d that a parametric pendulum oscillates in the vicinity of its unstable equilibrium positions to the case of waves of an unstable equilibrium position using a para- metric excitation (in the inverted pendulum experiment

Paris-Sud XI, Université de

349

Solution NMR structure of the DNA-binding domain from Scml2 (sex comb on midleg-like 2).  

PubMed

Scml2 is a member of the Polycomb group of proteins involved in epigenetic gene silencing. Human Scml2 is a part of a multisubunit protein complex, PRC1 (Polycomb repressive complex 1), which is responsible for maintenance of gene repression, prevention of chromatin remodeling, preservation of the "stemness" of the cell, and cell differentiation. Although the majority of PRC1 subunits have been recently characterized, the structure of Scml2 and its role in PRC1-mediated gene silencing remain unknown. In this work a conserved protein domain within human Scml2 has been identified, and its structure was determined by solution NMR spectroscopy. This module was named Scm-like embedded domain, or SLED. Evolutionarily, the SLED domain emerges in the first multicellular organisms, consistent with the role of Scml2 in cell differentiation. Furthermore, it is exclusively found within the Scm-like family of proteins, often accompanied by malignant brain tumor domain (MBT) and sterile ? motif (SAM) domains. The domain adopts a novel ?/? fold with no structural analogues found in the Protein Data Bank (PDB). The ability of the SLED to bind double-stranded DNA was also examined, and the isolated domain was shown to interact with DNA in a sequence-specific manner. Because PRC1 complexes localize to the promoters of a specific subset of developmental genes in vivo, the SLED domain of Scml2 may provide an important link connecting the PRC1 complexes to their target genes. PMID:24727478

Bezsonova, Irina

2014-05-30

350

Self-assembly of pH-responsive and fluorescent comb-like amphiphilic copolymers in aqueous media  

Microsoft Academic Search

Comb-like” graft copolymers, consisting of a poly((N-vinylcarbazole)-co-(4-vinylbenzyl chloride)) (P(NVK-co-VBC)) copolymer backbone from free radical polymerization and poly(((2-dimethylamino)ethyl methacrylate)-co-(tert-butyl acrylate)) (P(DMAEMA-co-tBA)) side chains from atom transfer radical polymerization (ATRP), were hydrolyzed to produce the acrylic acid (AAc)-containing “comb-like” graft copolymers of P(NVK-co-VBC)-comb-P(DMAEMA-co-AAc). The amphiphilic copolymers possess a fluorescent hydrophobic P(NVK-co-VBC) backbone and pH-sensitive hydrophilic P(DMAEMA-co-AAc) side chains. Arising from acid–base interaction

Min Li; Guo Liang Li; Zhiguo Zhang; Jun Li; Koon-Gee Neoh; En-Tang Kang

2010-01-01

351

Wide-bandwidth phase lock between a CW laser and a frequency comb based on a feed-forward configuration.  

PubMed

Wide-bandwidth phase lock between the tooth of a frequency comb and a CW extended-cavity diode laser at 1.55 ?m is achieved by the use of an acousto-optical frequency shifter in a feed-forward configuration. The coherence properties of the comb are efficiently transferred to the CW laser, whose linewidth is narrowed down to the ?10 KHz comb level. A maximum control bandwidth of ?0.6 MHz has been experimentally achieved, limited by the transit time of the acoustic wave inside the frequency shifter. PMID:22743465

Sala, T; Gatti, D; Gambetta, A; Coluccelli, N; Galzerano, G; Laporta, P; Marangoni, M

2012-07-01

352

Simultaneous low noise radio frequency tone and narrow linewidth optical comb generation from a regeneratively mode-locked laser  

NASA Astrophysics Data System (ADS)

A regeneratively mode-locked laser with simultaneous low noise radio frequency (RF) tone and optical comb generation is presented. The laser does not need any external RF signal and emits a pulse train at ˜10 GHz repetition rate with a 1.5-ps optical pulse width after compression. The generated RF tone has a signal-to-noise ratio of 121 dB/Hz and an RF fluctuation of 10-9 over 0.1 s. The optical frequency comb spacing is also at ˜10 GHz and the optical comb tooth has a linewidth of <1 kHz.

Ozdur, Ibrahim; Ozharar, Sarper; Delfyett, Peter J.

2014-10-01

353

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

NASA Astrophysics Data System (ADS)

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 ?s 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.

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

2015-01-01

354

Generation of green frequency comb from chirped ?(2) nonlinear photonic crystals  

NASA Astrophysics Data System (ADS)

Spectrally broad frequency comb generation over 510-555 nm range was reported on chirped quasi-phase-matching (QPM) ?(2) nonlinear photonic crystals of 12 mm length with periodicity stepwise increased from 5.9 ?m to 7.1 ?m. 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.

Lai, C.-M.; Chang, K.-H.; Yang, Z.-Y.; Fu, S.-H.; Tsai, S.-T.; Hsu, C.-W.; Yu, N. E.; Boudrioua, A.; Kung, A. H.; Peng, L.-H.

2014-12-01

355

Safer sex: Why bother? Sex and sexuality are important components of health. For many, sex is an integral part of life. Sex can be  

E-print Network

24 Safer sex: Why bother? Sex and sexuality are important components of health. For many, sex is an integral part of life. Sex can be pleasurable, fun and exciting. Unfortunately, sex can also lead to health of these consequences through safer sex practices. What are safer sex practices? We hear this term a lot, but what

Doedel, Eusebius

356

Sex differences in autism.  

PubMed

Comparisons were made between male and female children with autism, 384 boys and 91 girls, aged 3 years to 8 years, on nonverbal measures of intelligence, adaptive functioning, receptive vocabulary, perception, and eye-hand integration, and on ratings of affect, play, and relating and human interest. Males showed more advanced performances on eye-hand integration and perception skills on the Psychoeducational Profile (PEP) and had higher nonverbal IQs social quotients, and Peabody Picture Vocabulary Test (PPVT) IQs than females. When nonverbal IQ was controlled, the main effect of sex remained; however, sex differences on PPVT scores and on eye-hand integration and perception scale disappeared. Males showed more unusual visual responses and less appropriate, more stereotypic play than females. These results are discussed in terms of hypotheses concerning sex differences in genetic thresholds and in hemispheric lateralization. PMID:7161234

Lord, C; Schopler, E; Revicki, D

1982-12-01

357

How sex became gender.  

PubMed

This article argues that "sex" which had been commonly assumed in the West to refer to a permanent set of biological and behavioural traits particular to men and women, is gradually being replaced in general usage by "gender." Though feminist theorists attempted to attach a constructivist meaning to gender, a generation of developmental theorists, clinicians and analysts has imbued the term with the determinism and biological qualities formerly ascribed to "sex." The triumph of this materialist conception of gender is not assured, but it threatens our ability to think about gender identity as a historically-constructed category. PMID:20845571

Nye, Robert A

2010-01-01

358

Disestablishing Sex: The Case for Released-Time Sex Education  

ERIC Educational Resources Information Center

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…

Glanzer, Perry L.

2011-01-01

359

Sex Role Attitudes and Sex Role Stereotyping: Recent Literature.  

ERIC Educational Resources Information Center

This annotated bibliography profiles 17 publications examining sex role attitudes/sex role stereotyping from the perspectives of ethnicity, gender, and age. Cited in the section on ethnicity are studies of work satisfaction/family functioning among working-class Mexican-American women and cultural variations in sex typing by students in the United…

New Jersey Research Bulletin, 1996

1996-01-01

360

Sex And People.  

ERIC Educational Resources Information Center

This textbook for the college student emphasizes human sexuality as a part of the whole human life experience and contains a balance of biological, psychological, and sociological material. In 16 chapters the following topics are covered: (1) sex and society; (2) historical and cultural perspectives; (3) glandular control of sexual physiology; (4)…

Jones, Kenneth L.; And Others

361

Sex, Courtship, and Marriage.  

ERIC Educational Resources Information Center

The author presents an historical perspective on abortion, contraception and marriage as a prelude to an examination of changing attitudes toward sex. The article deals with the negative effects attributed to the increased incidence of early dating and early marriage of teenagers in the United States. The author also assumes positions on such…

Seiferth, Berniece

362

How Sex Attitudes Develop  

ERIC Educational Resources Information Center

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.

Arnstein, Helene S.

1976-01-01

363

Same-Sex Marriage  

Microsoft Academic Search

In this commentary, the legal ramifications and implications of the recent ruling by the Massachusetts Supreme Court allowing same-sex marriages to occur in that state are examined. The author then suggests a hypothetical scenario for what the future might look like assuming that the Massachusetts decision is not overturned by adoption of a state constitutional amendment.

Vincent J. Samar

2005-01-01

364

Child sex rings  

Microsoft Academic Search

Details of 11 child sex rings identified in one working class community were obtained by interviewing investigating police officers and examining health and social services records. The rings contained 14 adult male perpetrators and 175 children aged 6-15 years. Most perpetrators used child ringleaders to recruit victims; others became a \\

N J Wild; J M Wynne

1986-01-01

365

Sex, Technology and Morality.  

ERIC Educational Resources Information Center

Provides an overview of the course "Sex, Technology, and Morality" which focuses on the human reproductive process and examines the advances in reproductive technology. The course emphasizes the social, political, and ethical implications of actual and possible technologies associated with human reproduction. (ML)

Case, Verna; And Others

1986-01-01

366

Plant sex chromosomes.  

PubMed

Dioecious species are known in plants and, as in many animals, some have distinguishable sex chromosomes. Genetic maps have identified sex-determining regions in several plants, and mapped male-specific Y (MSY) regions of the chromosome in which crossing over and genetic recombination do not occur, allowing sequence divergence between the X and Y. Divergence values of the few X-Y gene pairs so far available show that recombination between different genes of Silene latifolia stopped at different times. Once recombination stops, MSY genome regions are predicted to accumulate repetitive sequences, including transposable elements, resulting in low gene density. This has been documented in papaya but not yet in other plants. Y-linked genes should also accumulate deleterious mutations, eventually being lost as dosage compensation evolves. The few available data suggest that many plant MSY genes are functional, perhaps because genes required for male gametophyte functions degenerate slowly. Detailed studies of sex-linked genes are needed to test for deleterious substitutions in Y genes, and to date the origins of plant sex chromosomes. PMID:18756079

Charlesworth, D

2008-01-01

367

Sex Education and Ideals  

ERIC Educational Resources Information Center

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 strict sense are rightfully called sexual…

de Ruyter, Doret J.; Spiecker, Ben

2008-01-01

368

Fabrication of high-aspect-ratio polymer-based electrostatic comb drives using the hot embossing technique  

NASA Astrophysics Data System (ADS)

We report on the formation of a lateral comb drive on poly-methyl-meth-acrylate (PMMA) using the hot embossing technique. A hot embossing mold insert is fabricated on a silicon wafer by means of lithography and inductive coupled plasma dry etching. The comb drive microstructure is hot embossed under a molding force of 35000 N at 130 °C. We demonstrate the comb drive, 80 units of interdigitated parallel capacitors with the finger gap and width both being 10 mum. The minimum feature size is 5 mum and the thickness of the structure is 60 mum, which makes the aspect ratio 12:1. The comb drive strokes 5 mum under an actuation potential of 180 V. We also present a brief description of the design and simulation with ANSYS.

Zhao, Yongjun; Cui, Tianhong

2003-05-01

369

Demonstration of on-sky calibration of astronomical spectra using a 25 GHz near-IR laser frequency comb.  

PubMed

We describe and characterize a 25 GHz laser frequency comb based on a cavity-filtered erbium fiber mode-locked laser. The comb provides a uniform array of optical frequencies spanning 1450 nm to 1700 nm, and is stabilized by use of a global positioning system referenced atomic clock. This comb was deployed at the 9.2 m Hobby-Eberly telescope at the McDonald Observatory where it was used as a radial velocity calibration source for the fiber-fed Pathfinder near-infrared spectrograph. Stellar targets were observed in three echelle orders over four nights, and radial velocity precision of ?10 m/s (?6 MHz) was achieved from the comb-calibrated spectra. PMID:22418547

Ycas, Gabriel G; Quinlan, Franklyn; Diddams, Scott A; Osterman, Steve; Mahadevan, Suvrath; Redman, Stephen; Terrien, Ryan; Ramsey, Lawrence; Bender, Chad F; Botzer, Brandon; Sigurdsson, Steinn

2012-03-12

370

Frequency-reconfigurable terahertz wireless transmission using an optical frequency comb based on radio-over-fiber technology  

NASA Astrophysics Data System (ADS)

We propose a prototype for frequency-reconfigurable terahertz (THz) wireless transmission using an optical comb based on radio-over-fiber technology. In the proposal, an electro-absorption modulator (EAM) followed by a phase modulator and an intensity modulator are used to generate a flat optical comb with a tunable frequency spacing. Then, a different THz signal can be generated by photo-mixing of optical two-tone signals from the comb lines. In the scheme, we obtain 46 comb lines within a 1-dB power deviation with an interval of about 10 GHz, and a THz up to 440 GHz is obtained. Moreover, a much higher bandwidth can be easily reached by adjusting the driving signal of the EAM. The feasibility and tunability of the proposed scheme are confirmed by the simulations. This method shows a simple cost-efficient configuration and good performance over long-distance delivery.

Zhang, Chan; Ning, Tigang; Li, Jing; Li, Chao; Ma, Shaoshuo

2014-12-01

371

Dyspareunia: Painful Sex for Women  

MedlinePLUS

... part of the genitals can cause pain during sex. Some conditions affect the skin around the vagina. ... types of birth control) does not fit correctly, sex may also be painful. Vaginismus (say: "vag-in- ...

372

Abnormal human sex chromosome constitutions  

SciTech Connect

Chapter 22, discusses abnormal human sex chromosome constitution. Aneuploidy of X chromosomes with a female phenotype, sex chromosome aneuploidy with a male phenotype, and various abnormalities in X chromosome behavior are described. 31 refs., 2 figs.

NONE

1993-12-31

373

Sex differences in college major  

Microsoft Academic Search

Analysis of sex differences in choice of college major in the United States in 1955 and 1973, using nationwide data. Data on college major distribution by sex; Analysis of differences; Empirical estimation. (Abstract copyright EBSCO.)

Solomon William Polachek

1978-01-01

374

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

PubMed

The development of comb rows in larval and adult Mnemiopsis leidyi and adult Pleurobrachia pileus is compared to regeneration of comb plates in these ctenophores. Late gastrula embryos and recently hatched cydippid larvae of Mnemiopsis have five comb plates in subsagittal rows and six comb plates in subtentacular rows. Subsagittal rows develop a new (sixth) comb plate and both types of rows add plates at similar rates until larvae reach the transition to the lobate form at ?5 mm size. New plate formation then accelerates in subsagittal rows that later extend on the growing oral lobes to become twice the length of subtentacular rows. Interplate ciliated grooves (ICGs) develop in an aboral-oral direction along comb rows, but ICG formation itself proceeds from oral to aboral between plates. New comb plates in Mnemiopsis larvae are added at both aboral and oral ends of rows. At aboral ends, new plates arise as during regeneration: local widening of a ciliated groove followed by formation of a short split plate that grows longer and wider and joins into a common plate. At oral ends, new plates arise as a single tuft of cilia before an ICG appears. Adult Mnemiopsis continue to make new plates at both ends of rows. The frequency of new aboral plate formation varies in the eight rows of an animal and seems unrelated to body size. In Pleurobrachia that lack ICGs, new comb plates at aboral ends arise between the first and second plates as a single small nonsplit plate, located either on the row midline or off-axis toward the subtentacular plane. As the new (now second) plate grows larger, its distance from the first and third plates increases. Size of the new second plate varies within the eight rows of the same animal, indicating asynchronous formation of plates as in Mnemiopsis. New oral plates arise as in Mnemiopsis. The different modes of comb plate formation in Mnemiopsis versus Pleurobrachia are accounted for by differences in mesogleal firmness and mechanisms of 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. PMID:22729952

Tamm, Sidney L

2012-09-01

375

Sex education in France.  

PubMed

The French Family Planning Movement (MFPF) has actively been involved in sex education within schools. In 1989, more than 1500 presentations were made to 23,000 pupils. Another activity is monitoring the application of statutes and regulations, for abortion, contraception, and sex education, and fighting to save and advance the rights of sexuality experts. Because of MFPF prominence in serious risks such as AIDs, sexual abuse, and rape, credibility has been enhanced. MFPF serves as a vehicle to change attitudes on male/female relationships. The government has permitted involvement in the preparation of a teaching program dealing with sexual abuse. The dominant influence of the Catholic Church on education has been evident since 1807. Up to WWI, religious morality was dominant. With Freud's contributions to the importance of sexuality in individual life, there were questions raised and a call for change in values and customs. In 1967, the statute was passed which authorized contraception, and sex education became an important issue. In 1973, Fontanet as Minister of Education outlined the recommendation for sex information and education in schools, including reproduction. Further official supportive recommendations were not made until 1985 when life education was entered into the primary syllabus. There was no provision even for teacher training; hence a wide variability in skills, commitment, and attitudes prevailed. MFPF reflects a position on tolerance in listening to others, expression and analysis of differences and critical thinking, identifying difficulties in talking about sex with respect to cultural and religious diversity, and help for the young in learning about their bodies, expressing feelings, and taking charge of emotions. PMID:12343168

Gallard, C

1991-05-01

376

Origin of Sex Revisited  

NASA Astrophysics Data System (ADS)

Why did sex ever arise in the first place? Why it does not disappear in view of the greater efficiency of asexuals? These are clearly two different questions, and we suggest here that the solution for the origin of sex does not necessarily come from theoretical considerations based on currently existing genetic systems. Thus, while we agree with a number of authors in that the emergence of sex (understood as the exchange of genetic material between genomes) is deeply rooted in the origin of life and happened during the very early stages in the transition from individual genes (`replicators') to bacteria-like cells (`reproducers'), we challenge the idea that recombinational repair was the major selective force for the emergence of sex. Taking the stochastic corrector model as a starting point, we provide arguments that question the putative costs of redundancy in primitive protocells. In addition, if genes that cause intragenomic conflict (i.e., parasites) are taken into account, it is certainly wrong to suggest that cellular fusion would be beneficial at the population level (although this strong claim needs some qualifications). However, when a continuous input of deleterious mutations that impair the fitness of the protocell as a whole is considered in the model (in the realistic range in which stable mutant distributions of quasi-species within compartments are established), there are circumstances when sex could be beneficial as a side effect of the dynamic equilibrium between cellular fusion-mutation-selection. The scenario we have explored numerically is fully consistent with the idea that the universal ancestor was not a discrete entity but an ensemble of proto-organisms that exchanged much genetic information.

Santos, Mauro; Zintzaras, Elias; Szathmáry, Eörs

2003-10-01

377

Sex and stripping  

PubMed Central

Wolbachia pipientis is known to infect only arthropods and nematodes (mainly filarial worms). A unique feature shared by the two Phyla is the ability to replace the exoskeleton, a process known as ecdysis. This shared characteristic is thought to reflect a common ancestry. Arthropod moulting is induced by the steroid hormone 20-hydroxyecdysone (20E) and a role for ecdysteroids in nematode ecdysis has also been suggested. Removing Wolbachia from filarial worms impairs the host’s development. From analyses of the genome of Wolbachia harbored by the filarial nematode Brugia malayi and that of its host, the bacterium may provide a source of heme, an essential component of cytochrome P450’s that are necessary for steroid hormone biosynthetic pathways. In arthropods, Wolbachia is a reproductive manipulator, inducing various phenotypic effects that may be due to differences in host physiology, in particular, endocrine-related processes governing development and reproduction. Insect steroids have well-defined roles in the coordination of multiple developmental processes, and in adults they control important aspects of reproduction, including ovarian development, oogenesis, sexual behavior, and in some taxa vitellogenin biosynthesis. According to some authors ecdysteroids may also act as sex hormones. In insects sex differentiation is generally thought to be a strictly genetic process, in which each cell decides its own sexual fate based on its sex chromosome constitution, but, surprisingly, recent data demonstrate that in Drosophila sex determination is not cell-autonomous, as it happens in mammals. Thus the presence of signals coordinating the development of a gender-specific phenotype cannot be excluded. This could explain why Wolbachia interferes with insect reproduction; and also could explain why Wolbachia interferes with insect development. Thus, is “sex (=reproduction) and stripping (=ecdysis)” the key to the intimate relationship between Wolbachia and its host? PMID:20585501

Pellecchia, Marco; Grève, Pierre; Daffonchio, Daniele; Bandi, Claudio; Alma, Alberto

2010-01-01

378

Generation of Flat Optical Frequency Comb based on Mach-Zehnder Modulator and Recirculating Frequency Shifter Loop  

NASA Astrophysics Data System (ADS)

We propose a novel scheme to generate optical frequency comb by using Mach-Zehnder modulator and recirculating frequency shifter loop based on IQ modulator driven by radio frequency clock signals. A system of 4 flat and stable comb lines generation based on Mach-Zehnder modulator is set as the seed light source of the recirculating loop. Through theorical analysis and simulation it is shown that the proposed theoretical model is proved in good agreement with simulation results.

Wu, Shibao; Li, Yulong; Fei, Yue; Hu, Faze

2014-06-01

379

Generation of Optical Combs in a WGM Resonator from a Bichromatic Pump  

NASA Technical Reports Server (NTRS)

Optical combs generated by a monolithic resonator with Kerrmedium can be used in a number of applications, including orbital clocks and frequency standards of extremely high accuracy, such as astronomy, molecular spectroscopy, and the like. The main difficulty of this approach is the relatively high pump power that has to be used in such devices, causing undesired thermorefractive effects, as well as stimulated Raman scattering, and limiting the optical comb quality and utility. In order to overcome this problem, this innovation uses a different approach to excitation of the nonlinear oscillations in a Kerr-nonlinear whispering gallery mode (WGM) resonator and generation of the optical comb. By coupling to the resonator two optical pump frequencies instead of just one, the efficiency of the comb source can be increased considerably. It therefore can operate in a lowerpower regime where the undesirable effects are not present. This process does not have a power threshold; therefore, the new optical component can easily be made strong enough to generate further components, making the optical comb spread in a cascade fashion. Additionally, the comb spacing can be made in an arbitrary number of the resonator free spectral ranges (FSR). The experimental setup for this innovation used a fluorite resonator with OMEGA= 13.56 GHz. This material has very low dispersion at the wavelength of 1.5 microns, so the resonator spectrum around this wavelength is highly equidistant. Light was coupled in and out of the resonator using two optical fibers polished at the optimal coupling angle. The gap between the resonator and the fibers, affecting the light coupling and the resonator loading, was controlled by piezo positioners. The light from the input fiber that did not go into the resonator reflected off of its rim, and was collected by a photodetector. This enabled observation and measurement of the (absorption) spectrum of the resonator. The input fiber combined light from two lasers centered at around 1,560 nanometers. Both laser frequencies were simultaneously scanned around the selected WGMs of the same family. However, they were separated by one, two, three, or ten FSRs. This was achieved by fine-tuning each laser frequency offset until the selected resonances overlap on the oscilloscope screen. The resonator quality factor Q = 7 x 10(exp 7) was relatively low to increase the linewidth and, therefore, the duty cycle of both lasers simultaneously coupled into their WGMs. The optical spectrum analyzer (OSA) connected to the output fiber was continuously acquiring data, asynchronously with the laser scan. The instrument was set to retain the peak power values; therefore, a trace recorded for a sufficiently long period of time reflected the situation with both lasers maximally coupled to the WGMs.

Strekalov, Dmitry V.; Yu, Nan; Matsko, Andrey B.

2010-01-01

380

FINDSITE(comb): a threading/structure-based, proteomic-scale virtual ligand screening approach.  

PubMed

Virtual ligand screening is an integral part of the modern drug discovery process. Traditional ligand-based, virtual screening approaches are fast but require a set of structurally diverse ligands known to bind to the target. Traditional structure-based approaches require high-resolution target protein structures and are computationally demanding. In contrast, the recently developed threading/structure-based FINDSITE-based approaches have the advantage that they are as fast as traditional ligand-based approaches and yet overcome the limitations of traditional ligand- or structure-based approaches. These new methods can use predicted low-resolution structures and infer the likelihood of a ligand binding to a target by utilizing ligand information excised from the target's remote or close homologous proteins and/or libraries of ligand binding databases. Here, we develop an improved version of FINDSITE, FINDSITE(filt), that filters out false positive ligands in threading identified templates by a better binding site detection procedure that includes information about the binding site amino acid similarity. We then combine FINDSITE(filt) with FINDSITE(X) that uses publicly available binding databases ChEMBL and DrugBank for virtual ligand screening. The combined approach, FINDSITE(comb), is compared to two traditional docking methods, AUTODOCK Vina and DOCK 6, on the DUD benchmark set. It is shown to be significantly better in terms of enrichment factor, dependence on target structure quality, and speed. FINDSITE(comb) is then tested for virtual ligand screening on a large set of 3576 generic targets from the DrugBank database as well as a set of 168 Human GPCRs. Excluding close homologues, FINDSITE(comb) gives an average enrichment factor of 52.1 for generic targets and 22.3 for GPCRs within the top 1% of the screened compound library. Around 65% of the targets have better than random enrichment factors. The performance is insensitive to target structure quality, as long as it has a TM-score ? 0.4 to native. Thus, FINDSITE(comb) makes the screening of millions of compounds across entire proteomes feasible. The FINDSITE(comb) web service is freely available for academic users at http://cssb.biology.gatech.edu/skolnick/webservice/FINDSITE-COMB/index.html. PMID:23240691

Zhou, Hongyi; Skolnick, Jeffrey

2013-01-28

381

Sex Education with Young Children.  

ERIC Educational Resources Information Center

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…

Koblinsky, Sally; And Others

1980-01-01

382

Liberating genetic variance through sex  

E-print Network

Liberating genetic variance through sex Andrew D. Peters and Sarah P. Otto* Summary Genetic of reproduction. Indeed, it has long been thought that sex enhances fitness variation and that this explains that sex need not always increase genetic variation in fitness. In particular, if fitness interactions

Otto, Sarah

383

Sex Stereotyping Hurts All Kids.  

ERIC Educational Resources Information Center

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)

Cutright, Melitta J.

1991-01-01

384

SEX CHROMOSOMES IN FLOWERING PLANTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sex chromosomes in dioecious and polygamous plants evolved as a mechanism for ensuring outcrossing to increase genetic variation in the offspring. Sex specificity has evolved in 75% of plant families by male sterile or female sterile mutations, but well defined heteromorphic sex chromosomes are know...

385

Optical-frequency-comb generation and entanglement with low-power optical input in a photonic molecule  

NASA Astrophysics Data System (ADS)

Optical-frequency combs consisting of equally spaced sharp lines in frequency space have triggered substantial advances in optical-frequency metrology and precision measurements and in applications such as laser-based gas sensing and molecular fingerprinting. Here, we propose a scheme to generate a type of optical-frequency combs and convert them from one cavity to the other in a hybrid optical system composed of a pair of coupled photonic crystal cavities called a photonic molecule (PM) and a single semiconductor quantum dot (QD) embedded in one cavity of the molecule. Optical-frequency combs are formed by the interaction between a cavity mode and a continuous-wave (CW) two-tone driving laser consisting of a pump field and a seed field via QD-induced strong nonlinearity. In this situation, the initial input pump and seed CW lasers can interact among each other and produce optical higher-order sidebands with equal spacing via parametric frequency conversion provided by QD-induced nonlinear optical effects. Using numerical simulations, it is clearly shown that the beat frequency of the two-tone components plays an important role in determining the comb spacing and matched frequency combs can be formed in the PM. We also demonstrate that the present interacting QD-PM system can serve as a platform to generate large-scale quantum entanglement between two comb modes. The results obtained here may be useful for real experiments in a photonic crystal platform.

Li, Jiahua; Yu, Rong; Ding, Chunling; Wang, Wei; Wu, Ying

2014-09-01

386

Effects of sex and sex roles on same-sex touch.  

PubMed

Touch is an important aspect of nonverbal behavior. Important aspects of the relationship of gender and sex roles with same-sex touch were highlighted. 259 subjects participated in the procedure, yielding a significant difference between men and women on same-sex touch. Further, androgyny was significantly correlated with ratings on the Same-sex Touching Scale. Specific conclusions regarding these findings were discussed. PMID:8022666

Crawford, C B

1994-04-01

387

Attitudes about Sex Selection and Sex Preference in Iranian Couples Referred for Sex Selection Technology  

PubMed Central

Background Gender preference is prevalent in some communities and using medical techniques to choose the baby's sex may cause the gender discrimination and gender imbalance in communities. Therefore, evaluating the gender preferences and attitudes towards using sex selection technologies seems to be necessary. Methods This cross-sectional study was conducted in Avicenna Fertility Center. Participants were 100 women with one child who were referred for sex selection. Data were collected through self-developed questionnaires. The questions were designed by the researchers at the experts’ panel. To determine the validity of the questionnaire, the viewpoints of professors specialized in these issues were obtained. The statistical analysis of the data was performed using SPSS software (Version 11.5), and p < 0.05 was considered significant. Results Tendency toward the male was more than female sex (55.5% male, 15.5% female and 28.5% no tendency). Majority of participants agreed with sex selection with medical reason and sex selection in order to balance the family. Women's level of education had positive effect on agreements to fetal sex selection with medical and non-medical reasons (p < 0.001). Conclusion Although gender preferences were toward the male sex but this preference was not very strong. Most participants agreed with non-medical sex selection for balancing the sex composition of their children. It doesn't seem that non-medical sex selection for family balancing causes severe sex imbalance in Iran. PMID:25717434

Ahmadi, Seyedeh Fatemeh; Shirzad, Mahdi; Kamali, Koorosh; Ranjbar, Fahimeh; Behjati-Ardakani, Zohreh; Akhondi, Mohammad Mehdi

2015-01-01

388

High power frequency comb based on mid-infrared quantum cascade laser at ? ˜ 9 ?m  

NASA Astrophysics Data System (ADS)

We investigate a frequency comb source based on a mid-infrared quantum cascade laser at ? ˜ 9 ?m 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.

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.

2015-02-01

389

Adaptive frequency comb illumination for interferometry in the case of nested two-beam cavities  

SciTech Connect

The homogeneity test of glass plates in a Fizeau interferometer is hampered by the superposition of multiple interference signals coming from the surfaces of the glass plate as well as the empty Fizeau cavity. To evaluate interferograms resulting from such nested cavities, various approaches such as the use of broadband light sources have been applied. In this paper, we propose an adaptive frequency comb interferometer to accomplish the cavity selection. An adjustable Fabry-Perot resonator is used to generate a variable frequency comb that can be matched to the length of the desired cavity. Owing to its flexibility, the number of measurements needed for the homogeneity test can be reduced to four. Furthermore, compared to approaches using a two-beam interferometer as a filter for the broadband light source, the visibility of the fringe system is considerably higher if a Fabry-Perot filter is applied.

Harder, Irina; Leuchs, Gerd; Mantel, Klaus; Schwider, Johannes

2011-09-01

390

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

NASA Astrophysics Data System (ADS)

The developed tools are used to create a representative volume element (RVE) of cementitious materials and then assess the diffusive properties. The algorithms developed in Combs target a fast placement of the inclusions and a fast generation of the RVE shape and its 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.

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

2014-06-01

391

A Laser Frequency Comb System for Absolute Calibration of the VTT Echelle Spectrograph  

NASA Astrophysics Data System (ADS)

A wavelength calibration system based on a laser frequency comb (LFC) was developed in a co-operation between the Kiepenheuer-Institut für Sonnenphysik, Freiburg, Germany and the Max-Planck-Institut für Quantenoptik, Garching, Germany for permanent installation at the German Vacuum Tower Telescope (VTT) on Tenerife, Canary Islands. The system was installed successfully in October 2011. By simultaneously recording the spectra from the Sun and the LFC, for each exposure a calibration curve can be derived from the known frequencies of the comb modes that is suitable for absolute calibration at the meters per second level. We briefly summarize some topics in solar physics that benefit from absolute spectroscopy and point out the advantages of LFC compared to traditional calibration techniques. We also sketch the basic setup of the VTT calibration system and its integration with the existing echelle spectrograph.

Doerr, H.-P.; Steinmetz, T.; Holzwarth, R.; Kentischer, T.; Schmidt, W.

2012-10-01

392

Performance of a laser frequency comb calibration system with a high-resolution solar echelle spectrograph  

NASA Astrophysics Data System (ADS)

Laser frequency combs (LFC) provide a direct link between the radio frequency (RF) and the optical frequency regime. The comb-like spectrum of an LFC is formed by exact equidistant laser modes, whose absolute optical frequencies are controlled by RF-references such as atomic clocks or GPS receivers. While nowadays LFCs are routinely used in metrological and spectroscopic fields, their application in astronomy was delayed until recently when systems became available with a mode spacing and wavelength coverage suitable for calibration of astronomical spectrographs. We developed a LFC based calibration system for the high-resolution echelle spectrograph at the German Vacuum Tower Telescope (VTT), located at the Teide observatory, Tenerife, Canary Islands. To characterize the calibration performance of the instrument, we use an all-fiber setup where sunlight and calibration light are fed to the spectrograph by the same single-mode fiber, eliminating systematic effects related to variable grating illumination.

Doerr, H.-P.; Kentischer, T. J.; Steinmetz, T.; Probst, R. A.; Franz, M.; Holzwarth, R.; Udem, Th.; Hänsch, T. W.; Schmidt, W.

2012-09-01

393

Hierarchical, multilayered cell walls reinforced by recycled silk cocoons enhance the structural integrity of honeybee combs.  

PubMed

We reveal the sophisticated and hierarchical structure of honeybee combs and measure the elastic properties of fresh and old natural honeycombs at different scales by optical microscope, environmental scanning electron microscope, nano/microindentation, and by tension and shear tests. We demonstrate that the comb walls are continuously strengthened and stiffened without becoming fragile by the addition of thin wax layers reinforced by recycled silk cocoons reminiscent of modern fiber-reinforced composite laminates. This is done to increase its margin of safety against collapse due to a temperature increase. Artificial engineering honeycombs mimic only the macroscopic geometry of natural honeycombs, but have yet to achieve the microstructural sophistication of their natural counterparts. The natural honeycombs serve as a prototype of truly biomimetic cellular materials with hitherto unattainable improvement in stiffness, strength, toughness, and thermal stability. PMID:20439765

Zhang, Kai; Duan, Huiling; Karihaloo, Bhushan L; Wang, Jianxiang

2010-05-25

394

Frequency-comb-referenced multi-wavelength profilometry for largely stepped surfaces.  

PubMed

3-D profiles of discontinuous surfaces patterned with high step structures are measured using four wavelengths generated by phase-locking to the frequency comb of an Er-doped fiber femtosecond laser stabilized to the Rb atomic clock. This frequency-comb-referenced method of multi-wavelength interferometry permits extending the phase non-ambiguity range by a factor of 64,500 while maintaining the sub-wavelength measurement precision of single-wavelength interferometry. Experimental results show a repeatability of 3.13 nm (one-sigma) in measuring step heights of 1800, 500, and 70 ?m. The proposed method is accurate enough for the standard calibration of gauge blocks and also fast to be suited for the industrial inspection of microelectronics products. PMID:23609685

Hyun, Sangwon; Choi, Minah; Chun, Byung Jae; Kim, Seungman; Kim, Seung-Woo; Kim, Young-Jin

2013-04-22

395

Adaptive frequency comb illumination for interferometry in the case of nested two-beam cavities  

NASA Astrophysics Data System (ADS)

The homogeneity test of glass plates in a Fizeau interferometer is hampered by the superposition of multiple interference signals coming from the surfaces of the glass plate as well as the empty Fizeau cavity. To evaluate interferograms resulting from such nested cavities, various approaches such as the use of broadband light sources have been applied. In this paper, we propose an adaptive frequency comb interferometer to accomplish the cavity selection. An adjustable Fabry--Perot resonator is used to generate a variable frequency comb that can be matched to the length of the desired cavity. Owing to its flexibility, the number of measurements needed for the homogeneity test can be reduced to four. Furthermore, compared to approaches using a two-beam interferometer as a filter for the broadband light source, the visibility of the fringe system is considerably higher if a Fabry--Perot filter is applied.

Harder, Irina; Leuchs, Gerd; Mantel, Klaus; Schwider, Johannes

2011-09-01

396

Hierarchical, multilayered cell walls reinforced by recycled silk cocoons enhance the structural integrity of honeybee combs  

PubMed Central

We reveal the sophisticated and hierarchical structure of honeybee combs and measure the elastic properties of fresh and old natural honeycombs at different scales by optical microscope, environmental scanning electron microscope, nano/microindentation, and by tension and shear tests. We demonstrate that the comb walls are continuously strengthened and stiffened without becoming fragile by the addition of thin wax layers reinforced by recycled silk cocoons reminiscent of modern fiber-reinforced composite laminates. This is done to increase its margin of safety against collapse due to a temperature increase. Artificial engineering honeycombs mimic only the macroscopic geometry of natural honeycombs, but have yet to achieve the microstructural sophistication of their natural counterparts. The natural honeycombs serve as a prototype of truly biomimetic cellular materials with hitherto unattainable improvement in stiffness, strength, toughness, and thermal stability. PMID:20439765

Zhang, Kai; Duan, Huiling; Karihaloo, Bhushan L.; Wang, Jianxiang

2010-01-01

397

Demonstration of atomic frequency comb memory for light with spin-wave storage  

E-print Network

We present a light-storage experiment in a praseodymium-doped crystal where the light is mapped onto an inhomogeneously broadened optical transition shaped into an atomic frequency comb. After absorption of the light the optical excitation is converted into a spin-wave excitation by a control pulse. A second control pulse reads the memory (on-demand) by reconverting the spin-wave excitation to an optical one, where the comb structure causes a photon-echo type rephasing of the dipole moments and directional retrieval of the light. This combination of photon echo and spin-wave storage allows us to store sub-microsecond (450ns) pulses for up to 20 microseconds. The scheme has a high potential for storing multiple temporal modes in the single photon regime, which is an important resource for future long-distance quantum communication based on quantum repeaters.

Mikael Afzelius; Imam Usmani; Atia Amari; Björn Lauritzen; Andreas Walther; Christoph Simon; Nicolas Sangouard; Ji?í Miná?; Hugues de Riedmatten; Nicolas Gisin; Stefan Kröll

2010-02-11

398

"Sex Hormones" in Secondary School Biology Textbooks  

ERIC Educational Resources Information Center

This study explores the extent to which the term "sex hormone" is used in science textbooks, and whether the use of the term "sex hormone" is associated with pre-empirical concepts of sex dualism, in particular the misconceptions that these so-called "sex hormones" are sex specific and restricted to sex-related physiological functioning. We found…

Nehm, Ross H.; Young, Rebecca

2008-01-01

399

Sex hormones and headache.  

PubMed

The normal female life cycle is associated with a number of hormonal milestones: menarche, pregnancy, contraceptive use, menopause, and the use of replacement sex hormones. Menarche marks the onset of menses and cyclic changes in hormone levels. Pregnancy is associated with rising noncyclic levels of sex hormones, and menopause with declining noncyclic levels. Hormonal contraceptive use during the reproductive years and hormone replacement in menopause are therapeutic hormonal interventions that alter the levels and cycling of sex hormones. These events and interventions may cause a change in the prevalence or intensity of headache. The menstrual cycle is the result of a carefully orchestrated sequence of interactions between the hypothalamus, pituitary, ovary, and endometrium, with the sex hormones acting as modulators and effectors at each level. Estrogen and progestins have potent effects on central serotonergic and opioid neurons, modulating both neuronal activity and receptor density. The primary trigger of Menstrually-related migraine (MM) appears to be the withdrawal of estrogen rather than the maintenance of sustained high or low estrogen levels. However, changes in the sustained estrogen levels with pregnancy (increased) and menopause (decreased) appear to affect headaches. Headaches associated with OC use or menopausal hormonal replacement therapy may be related, in part, to periodic discontinuation of oral sex hormone preparations. The treatment of migraine associated with changes in sex hormone levels is frequently difficult and the patients are often refractory to therapy. Based on what is known of the pathophysiology of migraine, we have attempted to provide a logical approach to the treatment of headaches that are associated with menses, menopause, and OCs using abortive and preventive medications and hormonal manipulations. Considerable evidence suggests a link between estrogen and progesterone, the female sex hormones, and migraine. (Silberstein and Merriam, 1997; Lipton and Stewart, 1993; Epstein et al., 1975; Goldstein and Chen, 1982; Selby and Lance, 1960) Although no gender difference is apparent in prepubertal children, with migraine occurring equally in 4p. 100 of boys and girls, (Goldstein and Chen, 1982, Waters and O'Connor, 1971) migraine occurs more frequently in adult women (18p. 100) than in men (6p. 100). (Lipton and Stewart, 1993) Migraine develops most frequently in the second decade, with the peak incidence occurring with adolescence. (Selby and Lance, 1960; Epstein et al., 1975) Menstrually-related migraine (MM) begins at menarche in 33p. 100 of affected women (Epstein et al. , 1975). MM occurs mainly at the time of menses in many migrainous women, and exclusively with menses (true menstrual migraine [TMM]) in some (Epstein et al., 1975). Menstrual migraine can be associated with other somatic complaints arising before and often persisting into menses, such as nausea, backache, breast tenderness, and cramps and like them appears to be the result of falling sex hormone levels (Silberstein and Merriam, 1997; American Psychiatric Association, 1994). In addition, premenstrual migraine can be associated with premenstrual dysphoric disorder (PDD), also called "premenstrual syndrome" (PMS), which is distinct from the physical symptoms of the perimenstrual period and is probably not directly driven by declining progesterone levels (Mortola, 1998). Migraine occurring during (rather than prior to) menstruation is usually not associated with PMS (Silberstein and Merriam, 1997). Migraine may worsen during the first trimester of pregnancy and, although many women become headache-free during the last two trimesters, 25p. 100 have no change in their migraine (Silberstein, 1997). MM typically improves with pregnancy, perhaps due to sustained high estrogen levels (Silberstein, 1997). Hormonal replacement with estrogens can exacerbate migraine and oral contraceptives (OCs) can change its character and frequency PMID:11139745

Silberstein, S D

2000-01-01

400

Carrier-envelope offset frequency noise analysis in Ti:sapphire frequency combs  

NASA Astrophysics Data System (ADS)

We experimentally study two Ti:sapphire optical frequency comb femtosecond regimes, respectively, with a linear and a nonlinear dependence of the carrier-envelope offset frequency (fCEO) on pump intensity. For both regimes, we study the effect of single- and multimode pump lasers on the fCEO phase noise. We demonstrate that the femtosecond regime is playing a more important role on the fCEO phase noise and stability than the pump laser type.

Sutyrin, Denis V.; Poli, Nicola; Beverini, Nicolò; Tino, Guglielmo M.

2014-12-01

401

Invasive Species Fact Sheets: Carp, Snail, Aphid, Comb Jelly, Chocolate Vine  

NSDL National Science Digital Library

This resource from ATEEC provides a number of fact sheets on invasive species which may be printed out or used as presentation material. The species described here are the big head carp, the giant African snail, the balsam wooly aphid, the comb jelly and the chocolate vine. The lesson plan is available for download as a PDF; users must create a free, quick login with ATEEC to access the materials.

402

Surface-micromachined electrostatic-comb driven scanning micromirrors for barcode scanners  

Microsoft Academic Search

This paper describes the design and fabrication of micromachined resonant scanners that have large scan angles at fast scan speeds. Driven by an electrostatic comb motor, these 200 ?m by 250 ?m scanning-micromirrors can scan about 12° (optical) at the resonance frequency of 3 kHz with a sinusoidal voltage input of 20 V in amplitude. Fabricated with a four-poly-layer silicon-surface-micromachining

Meng-Hsiung Kiang; Olav Solgaard; Richard S. Muller; Kam Y. Lau

1996-01-01

403

ComB: SNP Calling and Mapping Analysis for Color and Nucleotide Space Platforms  

PubMed Central

Abstract The determination of single nucleotide polymorphisms (SNPs) has become faster and more cost effective since the advent of short read data from next generation sequencing platforms such as Roche's 454 Sequencer, Illumina's Solexa platform, and Applied Biosystems SOLiD sequencer. The SOLiD sequencing platform, which is capable of producing more than 6?GB of sequence data in a single run, uses a unique encoding scheme where color reads represent transitions between adjacent nucleotides. The determination of SNPs from color reads usually involves the translation of color alignments to likely nucleotide strings to facilitate the use of tools designed for nucleotide reads. This technique results in the loss of significant information in the color read, producing many incorrect SNP calls, especially if regions exist with dense or adjacent polymorphism. Additionally, color reads align ambiguously and incorrectly more often than nucleotide reads making integrated SNP calling a difficult challenge. We have developed ComB, a SNP calling tool which operates directly in color space, using a Bayesian model to incorporate unique and ambiguous reads to iteratively determine SNP identity. ComB is capable of accurately calling short consecutive nucleotide polymorphisms and densely clustered SNPs; both of which other SNP calling tools fail to identify. ComB, which is capable of using billions of short reads to accurately and efficiently perform whole human genome SNP calling in parallel, is also capable of using sequence data or even integrating sequence and color space data sets. We use real and simulated data to demonstrate that ComB's iterative strategy and recalibration of quality scores allow it to discover more true SNPs while calling fewer false positives than tools which use only color alignments as well as tools which translate color reads to nucleotide strings. PMID:21563978

Souaiaia, Tade; Frazier, Zach

2011-01-01

404

CMOS-compatible, multiplexed source of heralded photon pairs: towards integrated quantum combs  

E-print Network

We report an integrated photon pair source based on a CMOS-compatible microring resonator that generates multiple, simultaneous, and independent photon pairs at different wavelengths in a frequency comb compatible with fiber communication wavelength division multiplexing channels (200 GHz channel separation) and with a linewidth that is compatible with quantum memories (110 MHz). It operates in a self-locked pump configuration, avoiding the need for active stabilization, making it extremely robust even at very low power levels.

Christian Reimer; Lucia Caspani; Matteo Clerici; Marcello Ferrera; Michael Kues; Marco Peccianti; Alessia Pasquazi; Luca Razzari; Brent E. Little; Sai T. Chu; David J. Moss; Roberto Morandotti

2014-03-24

405

Anti-fouling ultrafiltration membranes containing polyacrylonitrile- graft-poly(ethylene oxide) comb copolymer additives  

Microsoft Academic Search

Membrane fouling is one of the most important challenges faced in membrane ultrafiltration (UF) operations. In this study, polyacrylonitrile-graft-poly(ethylene oxide) (PAN-g-PEO), an amphiphilic comb copolymer with a water-insoluble polyacrylonitrile (PAN) backbone and hydrophilic poly(ethylene oxide) (PEO) side chains, was used as an additive in the manufacture of novel PAN UF membranes. During casting, the PAN-g-PEO additive segregates to form a

Ayse Asatekin; Seoktae Kang; Menachem Elimelech; Anne M. Mayes

2007-01-01

406

Frequency comb generation beyond the Lugiato-Lefever equation: multi-stability and super cavity solitons  

E-print Network

The generation of optical frequency combs in microresonators is considered without resorting to the mean-field approximation. New dynamical regimes are found to appear for high intracavity power that cannot be modeled using the Lugiato-Lefever equation. Using the Ikeda map we show the existence of multi-valued stationary states and analyse their stability. Period doubled patterns are considered and a novel type of super cavity soliton associated with the multi-stable states is predicted.

Hansson, Tobias

2015-01-01

407

Optical clockworks and the measurement of laser frequencies with a mode-locked frequency comb  

Microsoft Academic Search

Femtosecond laser-frequency comb techniques are vastly simplifying the measurement and synthesis of optical fre- quencies. A single mode-locked femtosecond laser, with its spec- trum broadened by self-phase modulation in a microstructured or tapered nonlinear fiber, can produce millions of sharp laser lines in a precise evenly spaced grid spanning much of the visible and near- infrared spectrum. The absolute frequency

R. Holzwarth; M. Zimmermann; Thomas Udem; T. W. Hansch

2001-01-01

408

Fabry–Pérot filter cavities for wide-spaced frequency combs with large spectral bandwidth  

Microsoft Academic Search

We use low-finesse Fabry–Pérot cavities in series to generate frequency combs with a large mode spacing in a way that allows\\u000a its application to a large optical bandwidth. The attenuation of laser modes closest to the pass bands of the cavity exceeds\\u000a 70 dB for a filter ratio of m=20 relative to the resonant modes centered within the pass bands. We

T. Steinmetz; T. Wilken; C. Araujo-Hauck; R. Holzwarth; T. W. Hänsch; T. Udem

2009-01-01

409

High-precision wavelength calibration of astronomical spectrographs with laser frequency combs  

Microsoft Academic Search

We describe a possible new technique for precise wavelength calibration of high-resolution astronomical spectrographs using femtosecond-pulsed mode-locked lasers controlled by stable oscillators such as atomic clocks. Such `frequency combs' provide a series of narrow modes which are uniformly spaced according to the laser's pulse repetition rate and whose absolute frequencies are known a priori with relative precision better than 10-12.

M. T. Murphy; Th. Udem; R. Holzwarth; A. Sizmann; L. Pasquini; C. Araujo-Hauck; H. Dekker; S. D'Odorico; M. Fischer; T. W. Hänsch; A. Manescau

2007-01-01

410

Direct Link between Microwave and Optical Frequencies with a 300 THz Femtosecond Laser Comb  

Microsoft Academic Search

We demonstrate a great simplification in the long-standing problem of measuring optical frequencies in terms of the cesium primary standard. An air-silica microstructure optical fiber broadens the frequency comb of a femtosecond laser to span the optical octave from 1064 to 532 nm, enabling us to measure the 282 THz frequency of an iodine-stabilized Nd:YAG laser directly in terms of

Scott A. Diddams; David J. Jones; Jun Ye; Steven T. Cundiff; John L. Hall; Jinendra K. Ranka; Robert S. Windeler; Ronald Holzwarth; Thomas Udem; T. W. Hänsch

2000-01-01

411

Amphiphilic comb-like polymer for harvest of conductive nano-cellulose  

Microsoft Academic Search

In this study, electrically conductive bacterial cellulose (BC) was prepared by culturing Gluconacetobacter xylinus in a carbon nanotube (CNT)-dispersed medium. The CNTs were dispersed by adopting a non-covalent approach in the presence of non-ionic amphiphilic comb-like polymer (CLP). Specifically, the hydrophobic backbone of CLP was chemophysically attached to the surface of the CNTs and the hydrophilic side chains were released

Jaeyoo Choi; Jie Cheng; Jinho Hyun

412

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

PubMed

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. PMID:25360955

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

2014-10-01

413

Widely time-dispersion-tuned fiber optical oscillator and frequency comb based on multiple nonlinear processes.  

PubMed

An all-fiber optical oscillator based on three nonlinear processes, namely stimulated Raman scattering and broad-band and narrow-band optical parametric amplification, is presented and experimentally characterized. The wavelength tuning is achieved by means of the time-dispersion technique and spans over 160 nm. Through the same technique a fast tunable optical frequency comb has been realized exploiting cascaded four-wave mixing. PMID:24322089

Chiarello, Fabrizio; Palmieri, Luca; Galtarossa, Andrea; Santagiustina, Marco

2013-11-15

414

Efficient Polyphase Decomposition of Comb Decimation Filters in DeltaSigma Analog-to-Digital Converters  

Microsoft Academic Search

A power efficient multi-rate multi-stage Combdecimation filter for mono-bit and multi-bit A A\\/D con-verters is presented. Polyphase decomposition in all stages,with high decimation factor in the first stage, is used tosignificantly reduce the sampling frequency of the Comb filter.Several implementations indicate that proper choice ofthe first stage decimation factor can considerably improvepower consumption, area and maximum sampling frequency.In multibit .A

H. Aboushady; Y. Dumonteix; M. m Louerat; H. Mehrez

2001-01-01

415

Application of filter sharpening to cascaded integrator-comb decimation filters  

Microsoft Academic Search

A new architecture for the implementation of high-order decimation filters is described. It combines the cascaded integrator-comb (CIC) multirate filter structure with filter sharpening techniques to improve the filter's passband response. This allows the first-stage CIC decimation filter to be followed by a fixed-coefficient second-stage filter, rather than a programmable filter, thereby achieving a significant hardware reduction over existing approaches.

Alan Y. Kwentus; Zhongnong Jiang

1997-01-01

416

A Comparison Design of Comb Decimators for Sigma-Delta Analog-to-Digital Converters  

Microsoft Academic Search

This paper presents a comparison design of comb decimators based on the non-recursive algorithm and the recursive algorithm. Compared with the recursive algorithm, the main advantage of the non-recursive algorithm is its abilities of reducing power consumption and increasing circuit speed especially when the decimation ratio and filter order are high. Based on the non-recursive algorithm, a decimator with programmable

Yonghong Gao; Lihong Jia; Jouni Isoaho; Hannu Tenhunen

2000-01-01

417

A fifth-order comb decimation filter for multi-standard transceiver applications  

Microsoft Academic Search

In multi-standard transceivers programmable decimation filters are required to perform channel select filtering at baseband since the channel bandwidths, sampling rates, and CNR requirements are different. This paper presents a low power fifth-order comb decimation filter with programmable decimation ratios (16 and 8) and sampling rates (12.8 MHz and 44.8 MHz) for GSM and DECT applications. The non-recursive architecture is

Yonghong Gao; Lihong Jia; Hannu Tenhunen

2000-01-01

418

Ciliary reversal without rotation of axonemal structures in ctenophore comb plates  

PubMed Central

We have used a newly discovered reversal response of ctenophore comb plates to investigate the structural mechanisms controlling the direction of ciliary bending. High K+ concentrations cause cydippid larvae of the ctenophore Pleurobrachia to swim backward. High-speed cine films of backward-swimming animals show a 180 degree reversal in beat direction of the comb plates. Ion substitution and blocking experiments with artificial seawaters demonstrate that ciliary reversal is a Ca++-dependent response. Comb plate cilia possess unique morphological markers for numbering specific outer-doublet microtubules and identifying the sidedness of the central pair. Comb plates of forward- and backward-swimming ctenophores were frozen in different stages of the beat cycle by an "instantaneous fixation" method. Analysis of transverse and longitudinal sections of instantaneously fixed cilia showed that the assembly of outer doublets does not twist during ciliary reversal. This directly confirms the existence of radial switching mechanism regulating the sequence of active sliding on opposite sides of the axoneme. We also found that the axis of the central pair always remains perpendicular to the plane of bending; more importantly, the ultrastructural marker showed that the central pair does not rotate during a 180 degree reversal in beat direction. Thus, the orientation of the central pair does not control the direction of ciliary bending (i.e., the pattern of active sliding around the axoneme). We discuss the validity of this finding for three-dimensional as well as two-dimensional ciliary beat cycles and conclude that models of central-pair function based on correlative data alone must now be re- examined in light of these new findings on causal relations. PMID:6114102

1981-01-01

419

Graphene oxide scrolls on hydrophobic substrates fabricated by molecular combing and their application in gas sensing.  

PubMed

Well-aligned graphene oxide (GO) scrolls are prepared through the controlled folding/scrolling of single-layer GO sheets using molecular combing on hydrophobic substrates, such as aged gold substrate, polydimethylsiloxane film, poly(L-lactic acid) film, and octadecyltrimethoxysilane-modified silicon dioxide. As a proof of concept, the gas sensor fabricated with a single reduced GO scroll is used to detect NO(2) gas with a concentration as low as 0.4 ppm. PMID:23065912

Li, Hai; Wu, Jumiati; Qi, Xiaoying; He, Qiyuan; Liusman, Cipto; Lu, Gang; Zhou, Xiaozhu; Zhang, Hua

2013-02-11

420

Sex, Songs, and Censorship  

Microsoft Academic Search

This study examines the tendency of popular music critics to focus their censorship attention on recordings containing sex-related imagery or explicitly sensual commentaries. The author explores the changing nature of lyrical interpretation from singularly audio sources through contemporary mixed-media presentations. The positive role of anti-authority statements as potential controls against abuses of political, religious, and economics power in a democratic

B. Lee Cooper

1995-01-01

421

Why Humans Have Sex  

Microsoft Academic Search

Historically, the reasons people have sex have been assumed to be few in number and simple in nature–to reproduce, to experience\\u000a pleasure, or to relieve sexual tension. Several theoretical perspectives suggest that motives for engaging in sexual intercourse\\u000a may be larger in number and psychologically complex in nature. Study 1 used a nomination procedure that identified 237 expressed\\u000a reasons for

Cindy M. Meston; David M. Buss

2007-01-01

422

The SW Sex enigma  

NASA Astrophysics Data System (ADS)

The SW Sex stars are a class of cataclysmic variables, originally identified because they shared a number of enigmatic properties - most notably, single-peaked emission lines instead of the double-peaked lines one would expect from their high-inclination accretion discs. We present high-time-resolution spectrophotometry of the eclipsing nova-like variables SW Sex and DW UMa, two of the founding members of the SW Sex class. Both systems show single-peaked Balmer and He ii ?4686 Å emission lines that appear to originate from a region in the disc that lies close to, but downstream of, the bright spot. The emission-line light curves are consistent with the finding from X-ray and ultraviolet observations that we predominantly see the flared disc rim and the unobscured back portion of the disc in these systems. In DW UMa, the He ii ?4686 Å emission line originates from close to the white dwarf and exhibits flaring. Such flares have been used to argue for magnetically channelled accretion, as in the intermediate polars, but the lack of a clear periodicity in the flares argues for a simpler model in which we are viewing the central regions of the disc through the non-uniform upper edge of a flared disc rim. We also observe narrow, blueshifted, transient absorption features in the Balmer lines of DW UMa, which we attribute to blobs of material ejected from the system, possibly by a magnetic propeller, that happen to be passing between us and the binary. Our results suggest that the solution to the SW Sex enigma is a combination of dominant bright-spot emission and a self-occulting disc. We also propose a simplified classification scheme for nova-like variables.

Dhillon, V. S.; Smith, D. A.; Marsh, T. R.

2013-02-01

423

The SW Sex enigma  

E-print Network

The SW Sex stars are a class of cataclysmic variables, originally identified because they shared a number of enigmatic properties - most notably, single-peaked emission lines instead of the double-peaked lines one would expect from their high-inclination accretion discs. We present high time-resolution spectrophotometry of the eclipsing nova-like variables SW Sex and DW UMa, two of the founding members of the SW Sex class. Both systems show single-peaked Balmer and HeII 4686A emission lines that appear to originate from a region in the disc that lies close to, but downstream of, the bright spot. The emission-line light curves are consistent with the finding from X-ray and ultraviolet observations that we predominantly see the flared disc rim and the unobscured back portion of the disc in these systems. In DW UMa, the HeII 4686A emission line originates from close to the white dwarf and exhibits flaring. Such flares have been used to argue for magnetically-channelled accretion, as in the intermediate polars, b...

Dhillon, V S; Marsh, T R

2012-01-01

424

xComb: a cross-linked peptide database approach to protein-protein interaction analysis  

PubMed Central

We developed an informatic method to identify tandem mass spectra composed of chemically cross-linked peptides from those of linear peptides and to assign sequence to each of the two unique peptide sequences. For a given set of proteins the key software tool, xComb, combs through all theoretically feasible cross-linked peptides to create a database consisting of a subset of all combinations represented as peptide FASTA files. The xComb library of select theoretical cross-linked peptides may then be used as a database that is examined by a standard proteomic search engine to match tandem mass spectral datasets to identify cross-linked peptides. The database search may be conducted against as many as 50 proteins with a number of common proteomic search engines, e.g. Phenyx, Sequest, OMSSA, Mascot and X!Tandem. By searching against a peptide library of linearized, cross-linked peptides, rather than a linearized protein library, search times are decreased and the process is decoupled from any specific search engine. A further benefit of decoupling from the search engine is that protein cross-linking studies may be conducted with readily available informatics tools for which scoring routines already exist within the proteomic community. PMID:20302351

Panchaud, Alexandre; Singh, Pragya; Shaffer, Scott A.; Goodlett, David R.

2010-01-01

425

Gigahertz frequency comb from a diode-pumped solid-state laser.  

PubMed

We present the first stabilization of the frequency comb offset from a diode-pumped gigahertz solid-state laser oscillator. No additional external amplification and/or compression of the output pulses is required. The laser is reliably modelocked using a SESAM and is based on a diode-pumped Yb:CALGO gain crystal. It generates 1.7-W average output power and pulse durations as short as 64 fs at a pulse repetition rate of 1 GHz. We generate an octave-spanning supercontinuum in a highly nonlinear fiber and use the standard f-to-2f carrier-envelope offset (CEO) frequency fCEO detection method. As a pump source, we use a reliable and cost-efficient commercial diode laser. Its multi-spatial-mode beam profile leads to a relatively broad frequency comb offset beat signal, which nevertheless can be phase-locked by feedback to its current. Using improved electronics, we reached a feedback-loop-bandwidth of up to 300 kHz. A combination of digital and analog electronics is used to achieve a tight phase-lock of fCEO to an external microwave reference with a low in-loop residual integrated phase-noise of 744 mrad in an integration bandwidth of [1 Hz, 5 MHz]. An analysis of the laser noise and response functions is presented which gives detailed insights into the CEO stabilization of this frequency comb. PMID:25607050

Klenner, Alexander; Schilt, Stéphane; Südmeyer, Thomas; Keller, Ursula

2014-12-15

426

Design of optical frequency comb for sky survey astronomical spectrograph calibration  

NASA Astrophysics Data System (ADS)

Sky survey telescope is an important approach to ground-based observation of external galaxies, and further research on large-scale structure of the universe, galaxy formation and evolution. Sky survey spectrograph (SSS) with low resolution is included in such kind of telescope system. The spectral measurement accuracy of SSS will determine the accuracy and scientific value of mass spectral data. Currently iodine absorption cell or Thorium-Argon lamp is adopted as the calibration source for SSS. However, the spectral lines are sparse, with non-uniform spectral interval and intensity, and even instable over long time. The novel astro-comb cannot be applied to SSS directly because the spectral intervals are still too dense to be used in SSS with relatively lower resolution. In this paper, spectral mode filtering method with acceptable energy reduction and accurate spectral line frequency is studied to improve current astro-comb to properly distributed spectral lines and solve the above critical problem. Aiming at calibration for the measuring of the spectral lines in 3700-5900 Å region, we design an improved astro-comb system based on Erbium-doped fiber laser and Fabry-Perot filter series. Feasible systematical parameters are given. It will help develop a novel calibration approach with systematic error reduction to less than 1/10000 of that of the current calibration methods.

Hu, Yao; Wang, Xiang

2013-12-01

427

Optical frequency comb generation based on chirping of Mach-Zehnder Modulators  

NASA Astrophysics Data System (ADS)

A new approach for the generation of an optical frequency comb, based on chirping of modulators, is proposed and numerically demonstrated. The setup includes two cascaded Mach-Zehnder Modulators (MZMs), a sinusoidal wave oscillator, and an electrical time delay. The first MZM is driven directly by a sinusoidal wave, while the second MZM is driven by a delayed replica of the sinusoidal wave. A mathematical model of the proposed system is formulated and modeled using the Matlab software. It is shown that the number of the frequency lines is directly proportional to the chirp factor. In order to achieve the highest number of frequency comb lines with the best flatness, the time delay between the driving voltages of the two MZMs is optimized. Our results reveal that at least 51 frequency lines can be observed at the output spectrum. In addition, 27 of these lines have power fluctuations of less than 1 dB. The performance of the proposed system is also simulated using a split-step numerical analysis. An optical frequency comb, with tunable frequency spacing ranging from 5 to 40 GHz, is successfully generated.

Hmood, Jassim K.; Emami, Siamak D.; Noordin, Kamarul A.; Ahmad, Harith; Harun, Sulaiman W.; Shalaby, Hossam M. H.

2015-06-01

428

Absolutely continuous energy bands and extended electronic states in an aperiodic comb-shaped nanostructure  

NASA Astrophysics Data System (ADS)

The nature of electronic eigenstates and quantum transport in a comb-shaped Fibonacci nanostructure model is investigated within a tight-binding framework. Periodic linear chains are side-attached to a Fibonacci chain, giving it the shape of an aperiodic comb. The effect of the side-attachments on the usual Cantor set energy spectrum of a Fibonacci chain is analyzed using the Greens function technique. A special correlation between the coupling of the side-attached chain with the Fibonacci chain and the inter-atomic coupling of the Fibonacci chain results in a dramatic triggering of the fragmented Cantor set energy spectrum into multiple sets of continuous sub-bands of extended eigenstates. The result is valid even for a disordered comb and turns out to be a rare exception of the conventional Anderson localization problem. The electronic transport thus can be made selectively ballistic within desired energy regimes. The number and the width of such continuous sub-bands can be easily controlled by tuning the number of atomic sites in the side-coupled periodic linear chains. This gives us a scope of proposing such aperiodic nanostructures as potential candidates for prospective energy selective nanoscale filtering devices.

Pal, Biplab

2014-07-01

429

Sex-role orientation and attachment styles of sex offenders.  

PubMed

Given the increase of individuals who have a history of sexual offenses, there has been an increase in research on the etiology of sex-offending behavior. The present purpose was to evaluate the relationship between sex-role orientation and attachment styles of males who were sex offenders. Analysis yielded statistically significant differences between comparison (n = 22) and clinical groups (n = 21) in gender roles, with little sign of the androgynous gender type for sex offenders. The offender group showed significantly lower frequency of androgyny scores and significantly higher scores on feminine and undifferentiated orientations, supporting the theoretical view of sex offenders as being "cross-sex-typed." In addition, the sex offender group had a significantly higher mean score on anxious-avoidant relationship attachment. Based on the present findings, there appears to be a need to help sex offenders explore how their gender roles may relate to their sex-offending behavior and assist sex offenders in the development of adaptive relationships with reduced anxiety and ambivalence. PMID:22662415

Schneck, Mary M; Bowers, Thomas G; Turkson, Maria A

2012-04-01

430

Proposal of Effusibacillus lacus gen. nov., sp. nov., and reclassification of Alicyclobacillus pohliae as Effusibacillus pohliae comb. nov. and Alicyclobacillus consociatus as Effusibacillus consociatus comb. nov.  

PubMed

A novel thermophilic, facultatively anaerobic bacterium, strain skLN1(T), was isolated from the sediment of a freshwater lake in Japan. Cells of strain skLN1(T) were rod-shaped and Gram-stain-variable. A KOH lysis test suggested that the cell wall of the isolate has a Gram-positive structure. For aerobic growth, the optimum pH was pH 7.25-7.50 and the optimum temperature was 50-52 °C. The G+C content of the genomic DNA was 50.8 mol%. Nitrate was reduced to nitrite. Alicyclic fatty acids were not detected, and branched-chain fatty acids were major components in the cellular fatty acid profile. MK-7 was the predominant respiratory quinone. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolated strain was related most closely to Alicyclobacillus consociatus CCUG 53762(T) (95% similarity). This analysis also showed that the monophyly of the genus Alicyclobacillus had been lost. On the basis of phylogenetic and phenotypic characterization, Effusibacillus lacus gen. nov., sp. nov. is proposed. The type strain of Effusibacillus lacus is skLN1(T) (?=?NBRC 109614(T)?=?DSM 27172(T)). It is also proposed that Alicyclobacillus pohliae and Alicyclobacillus consociatus should be reclassified to the genus Effusibacillus as Effusibacillus pohliae comb. nov. and Effusibacillus consociatus comb. nov., respectively. PMID:24860109

Watanabe, Miho; Kojima, Hisaya; Fukui, Manabu

2014-08-01

431

Reclassification of Methanogenium tationis and Methanogenium liminatans as Methanofollis tationis gen. nov., comb. nov. and Methanofollis liminatans comb. nov. and description of a new strain of Methanofollis liminatans  

NASA Technical Reports Server (NTRS)

Sequencing of 16S rRNA genes and phylogenetic analysis of Methanogenium tationis DSM 2702T (OCM 43T) (T = type strain) and Methanogenium liminatans GKZPZT (= DSM 4140T) as well as other members of the family Methanomicrobiaceae revealed that both species belong to a separate line of descent within this family. In addition, a new strain of Methanogenium liminatans, strain BM1 (= DSM 10196), was isolated from a butyrate-degrading, fluidized bed reactor and characterized. Cells of both species are mesophilic, highly irregular cocci that use H2/CO2 and formate for growth and methanogenesis. In addition, Methanogenium liminatans strains GKZPZT and BM1 used 2-propanol/CO2, 2-butanol/CO2 and cyclopentanol/CO2. Both species contained diether and tetraether lipids. The polar lipids comprised amino-phosphopentanetetrol derivatives, which appear to be characteristic lipids within the family Methanomicrobiaceae. The pattern of glycolipids, phosphoglycolipids and amino-phosphoglycolipids was consistent with the assignment of these two species to a taxon within the family Methanomicrobiaceae, but also permitted them to be distinguished from other higher taxa within this family. The G+C contents of the DNA of Methanogenium tationis and Methanogenium liminatans were 54 and 60 mol% (Tm and HPLC), respectively. On the basis of the data presented, the transfer of Methanogenium tationis and Methanogenium liminatans to the genus Methanofollis gen. nov. as Methanofollis tationis comb. nov. and Methanofollis liminatans comb. nov., respectively, is proposed, with Methanofollis tationis as the type species.

Zellner, G.; Boone, D. R.; Keswani, J.; Whitman, W. B.; Woese, C. R.; Hagelstein, A.; Tindall, B. J.; Stackebrandt, E.

1999-01-01

432

Sexing sperm of domestic animals.  

PubMed

The ability to preselect or predetermine the sex of offspring prior to conception is a highly desired technological tool for assisted female breeding programs specifically for milk production, and in males, for meat production and increasing livestock numbers. The current technology is based on the well-known differences in X- and Y-sperm in the amount of DNA. The technology uses modified flow cytometric instrumentation for sorting X- and Y-bearing sperm. The method can be validated on the basis of live births, laboratory reanalysis of sorted sperm for DNA content, and embryo biopsy for sex determination. Currently, the sex of animals has been predetermined with 90 % accuracy by sexing spermatozoa. In the bovine breeding industry, flow cytometric sperm sexing has not fulfilled its original promise. Sexed sperm doses are too expensive for widespread application while the fertility of sexed sperm doses is lower than unsexed ones. Essentially all bovine sexed semen is frozen and then applied through artificial insemination (AI) or in vitro fertilization. There is still a need in the animal breeding industry to develop a technique for sperm sexing that provides sufficient spermatozoa for AI doses, does not compromise sperm fertility, and is widely applicable to a range of species. In this review, we will summarize the current state-of-the-art in sex preselection in domestic animals and some wildlife species using flow cytometric sperm-sorting of X from Y sperm based on DNA differences. PMID:22829354

Espinosa-Cervantes, Román; Córdova-Izquierdo, Alejandro

2013-01-01

433

Sex Typing and the Avoidance of Cross-Sex Behavior  

Microsoft Academic Search

This article presents evidence for the hypothesis that cross-sex behavior is motivationally problematic for sex-typed individuals and that they actively avoid it as a result. In particular, when asked to indicate which of a series of paired activities they would prefer to perform for pay while being photographed, sex-typed subjects were more likely than either androgynous or sexreversed subjects to

Sandra L. Bem; Ellen Lenney

1976-01-01

434

Sex and justice.  

PubMed

On the 25th anniversary of Pope Paul VI's signing of the Humanae Vitae "On the Regulation of Birth" and his reaffirming of the ban on birth control, this most controversial encyclical's anniversary will pass unnoticed at east in most US churches. Silence prevails as the utmost expression of dissent that priests and bishops can safely risk. Under the papacy of John Paul II, fidelity to the contraceptive ban is a loyalty test; public dissent by theologians and clerics invites reproach and punishment. Yet a church-sanctioned survey of priests found that more than 80% of Catholic clergy did not insist on the acceptance of the teaching in the confessional. The typical American Catholic uses birth control in the same numbers as everyone else. The Humanae Vitae's claims about sexuality are even more damaging than its position on banning contraception. It exalts sex as sacred, yet implies that sex is an animal impulse that must be suppressed, thus glorifying abstinence. According to Humanae Vitae, "each and every marriage act must remain open to the transmission of life." By insisting on the primacy of procreation in sexual behavior, the church loses its ability to sensibly address an array of societal problems, including AIDS, teen pregnancy, and population pressures. Many Catholics, far ahead of the institution, have crafted their own sexual ethic using the perspective the church uses in every other issue that comes before it: justice. With justice regulating sexual behavior, the concerns become one of respect and equality, the good of one's partner, the welfare of one's children, and the values of determining the number and spacing of births. With this viewpoint, Catholics and others would listen when the church talks about sex; now there is only silence. PMID:12178861

Kissling, F

1994-01-01

435

The price of sex.  

PubMed

The World Health Organization (WHO) ranks Cote d'Ivoire as the sixth worst affected country in Africa in terms of the number of AIDS cases. WHO figures indicate the presence of 6836 AIDS cases in Cote d'Ivoire, but doctors believe the actual prevalence to be about 7 times greater. By 2001, it is thought that as many as 30,000 AIDS-related deaths will occur annually in the country. Abidjan is particularly affected by HIV infection and AIDS, with AIDS being the main cause of death among adult men in the city and the second leading cause of death among women. 15% of blood donors, an estimated 50% of the city's prostitutes, and 12% of women in Abidjan's pediatric wards are infected with HIV. The level of HIV infection among mothers on the pediatric wards alone means that approximately 3300 HIV-infected babies are born annually in the city. Abidjan has a thriving commercial sex industry and district in which many prostitutes have sexual intercourse without using a condom even though they may be aware of the risk of HIV infection. It is difficult for the women who want to use condoms to convince their male clients to do so when the clients can easily find other prostitutes who will have unprotected sex. Women who would otherwise protect themselves are therefore forced to have unprotected sex if they want to stay in business. Educational programs designed to change behavior have remained ineffective. Official lassitude about the threat of HIV/AIDS and general ignorance and disbelief in the population about the epidemic have facilitated the spread of HIV in Cote d'Ivoire. Programs to market condoms and educate prostitutes are being launched. PMID:12348299

Huband, M

1991-01-01

436

Why Sex is Good  

NSDL National Science Digital Library

This interrupted case is based on a 2005 article in Nature written by three scientists from the Imperial College London that deals with the issue of sexual vs. asexual reproduction and their relative merits—a question that has bedeviled biologists for over 100 years. The article serves as the final stage of this case focusing on why sex is good (at least in some circumstances). Written for a general biology class where the question of evolution is considered, the case would also be appropriate for use in an evolution or ecology course.

Clyde Freeman Herreid

2005-01-01

437

Mixed-Sex or Single-Sex Education: How Would Young People Like Their Sex Education and Why?  

ERIC Educational Resources Information Center

Examined adolescents views about sex education, specifically their views about interaction in single- and mixed-sex groups. Surveys of English secondary school students indicated that most girls, and one-third of boys, want some or all of their sex education to be delivered in single-sex groups. Girls' experiences of sex education with boys…

Strange, Vicki; Forrest, Simon; Oakley, Ann

2003-01-01

438

Bayesian Reconstruction of Two-Sex Populations by Age: Estimating Sex Ratios at Birth and Sex Ratios of  

E-print Network

Bayesian Reconstruction of Two-Sex Populations by Age: Estimating Sex Ratios at Birth and Sex past with uncertainty, produced estimates for female-only populations. Here we show how two-sex populations can be similarly reconstructed and probabilistic estimates of various sex ratio quantities

Raftery, Adrian

439

[Sex cord gonadal stromal tumors].  

PubMed

According to the World Health Organization (WHO) classification from 2004, sex cord gonadal stromal tumors are divided into Leydig cell tumors, Sertoli cell tumors, granulosa cell tumors, tumors of the thecoma-fibroma group, incompletely differentiated sex cord gonadal stromal tumors, mixed forms of sex cord gonadal stromal tumors and tumors containing both germ cell and sex cord gonadal stromal elements. These tumors can appear sporadically or in combination with hereditary syndromes. To diagnose these rare tumors the combination of characteristic morphological aspects and various immunohistochemical markers is useful. Latest investigations demonstrate the potential role of mutation analyses in the diagnosis of this heterogeneous group of tumors. PMID:24819979

Bremmer, F; Behnes, C L; Radzun, H-J; Bettstetter, M; Schweyer, S

2014-05-01

440

A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s$^{-1}$  

E-print Network

Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm/s (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 Earthlike orbit, a precision of 5 cm/s is necessary. The combination of a laser frequency comb with a Fabry-Perot 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 (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 in astronomical radial velocity measurements.

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

2008-04-07

441

THE INDIVIDUAL, SOCIETY AND SEX. BACKGROUND READINGS FOR SEX EDUCATORS.  

ERIC Educational Resources Information Center

THIS BOOK IS DESIGNED AS A TEXT PRIMARILY FOR COLLEGE STUDENTS PREPARING TO TEACH SEX EDUCATION OR "EDUCATION IN THE NATURE OF HUMAN SEXUALITY AND THE RELATIONS BETWEEN THE SEXES" IN ELEMENTARY AND SECONDARY SCHOOLS. AN ATTEMPT IS MADE BY THE 13 WRITERS, MOST OF THEM SOCIOLOGISTS OR PSYCHOLOGISTS, TO DISTINGUISH BETWEEN THE KNOWLEDGE WHICH THE…

BRODERICK, CARLFRED B.; AND OTHERS

442

Elusive sex acts: pleasure and politics in Norwegian sex education  

Microsoft Academic Search

While there is little political opposition towards sex education as such in Norway, recent attempts at reforming the subject reveal underlying heteronormative presumptions that seem resistant to reform. While a focus on homosexuality is included in the national curriculum at all levels of compulsory education, the sexual practices involved in same-sex relations remain conspicuously absent from the education provided. This

Stine H. Bang Svendsen

2012-01-01

443

Sex ratio dependent dispersal when sex ratios vary between patches  

Microsoft Academic Search

Female biased sex ratios reduce competition between brothers when mating takes place within local patches. Male dispersal prior to mating is another strategy that reduces competition between brothers. One may thus expect these two traits to co-evolve and this is partially met in that sex ratios becomes less female biased as dispersal increases. However, the evolutionary stable degree of dispersal

Ronald M. Nelson; Jaco M. Greeff

2011-01-01

444

Sex ratio variation and sex determination in Urtica dioica  

Microsoft Academic Search

This thesis will first document on variation in progeny sex ratios among individual female plants of Urtica dioica at our field site in Meijendel (Chapter 2). Next, we show that there is also considerable sex ratio variation among male and female flowering shoots in 26 natural populations studied (Chapter 3). Additionally, we studied life history traits of male and female

Grit Anja Glawe

2006-01-01

445

Teacher Expressiveness: Effects of Teacher Sex and Student Sex.  

ERIC Educational Resources Information Center

Student ratings of college professors play an important role in many employment decisions. One factor strongly associated with student ratings is teacher expressiveness. A study was conducted to explore the effects of teacher expressiveness, teacher sex, and student sex on student ratings of their instructor, student perceptions of their…

Basow, Susan A.

446

Sex differences in same- and cross-sex supportive relationships  

Microsoft Academic Search

The current study focused on sex differences in same- and cross-sex supportive relationships. Subjects, 249 female and 103 male volunteers, completed a questionnaire designed to assess the nature and quality of supportive relationships. Four dimensions of relationships were examined: the relative frequency and patterning of interactions, closeness, diversity of interactions, and interpersonal perception. A 2×2 multivariate analysis of variance (MANOVA)

Robin A. Buhrke; Dale R. Fuqua

1987-01-01

447

Sex Differences in Reactions to Outperforming Same-Sex Friends  

ERIC Educational Resources Information Center

The current studies were designed to examine whether female adolescents have more negative reactions than male adolescents to achieving more than their same-sex friends. In Study 1, 51 females and 48 males from grades 8 and 10 were administered questions assessing their reactions to performing better than their closest same-sex friends in four…

Benenson, Joyce F.; Schinazi, Joy

2004-01-01

448

Sex-specific DNA in reptiles with temperature sex determination.  

PubMed

Banded krait minor ("Bkm") satellite DNA, originating in the W-chromosome of the snake Bungarus fasciatus, has been found in the genome of diverse eukaryotic species including fruit fly, quail, and horse. Concentrations of Bkm have been found in the presumptive W-chromosome of snakes with isomorphic sex chromosomes and in the male-determining region of the Y-chromosome in mouse and man. We therefore asked whether Bkm-related DNA might be present in quantitative excess in DNA from males or females in two related species of sea turtle, Chelonia mydas, in which sex is determined by the temperature of the incubating egg, and Lepidochelys kempi, in which the critical sex-determining temperature has recently been described. Filter hybridization with the Bkm 2(8) probe revealed male-specific fragments in both species; female-specific fragments were also revealed in C. mydas. Sex-specific DNA sequences in temperature-sex-determined species such as Kemp's ridley and the green turtle were unexpected, but could be explained if there were an underlying genetic mode of sex determination in these animals, or alternatively, if temperature-influenced sex determination involved structural modifications in DNA adjacent to, or directly concerned with, the sex-determining genes. If these results are confirmed across a broader sample of sea turtles, the techniques described in this paper might be used routinely to identify gener in the young of these endangered animals, in which male and female are grossly indistinguishable. PMID:2156951

Demas, S; Duronslet, M; Wachtel, S; Caillouet, C; Nakamura, D

1990-03-01

449

Sex, the Bible and Modern Man  

ERIC Educational Resources Information Center

The author suggests four basic affirmations which the Bible makes concerning sex: sex is good; sex is more than a physical relationship; sex operates within culturally proscribed boundaries; and sexual gilt is forgiveable regardless of the deviation. These affirmations are discussed in relation to the teaching of sex education in the schools. (CJ)

Young, Robert D.

1970-01-01

450

Same-sex and cross-sex relationships.  

PubMed

This study examines same-sex and cross-sex close relationships of older adults using a national probability sample survey. Specifically, we focus on three relational characteristics: psychological closeness, geographical proximity, and support exchange. These characteristics are examined with four types of close relationships: spouse, children, siblings, and friends. Results indicate that although older persons tend to have more women in the network and receive more support from those women, they are not necessarily closer, either psychologically or geographically, to the women than to the men in their network. The data also suggest a noticeable shift from same-sex alliance to female salience in the networks when older men, as well as women, become widowed and require more support. The findings are discussed in light of three principles which have guided research on sex differences in close relationships: relation hierarchy, femaleness, and sex commonality. PMID:8931625

Akiyama, H; Elliott, K; Antonucci, T C

1996-11-01

451

Transfer of Bacillus mucilaginosus and Bacillus edaphicus to the genus Paenibacillus as Paenibacillus mucilaginosus comb. nov. and Paenibacillus edaphicus comb. nov.  

PubMed

Bacillus mucilaginosus and Bacillus edaphicus were reclassified based on their 16S rRNA and gyrB gene sequences, DNA-DNA hybridization, fatty acid methyl esters and other taxonomic characteristics. Phylogenetic analysis based on 16S rRNA and gyrB gene sequences indicated that strains of B. mucilaginosus and B. edaphicus were members of the genus Paenibacillus, with over 90.4 % and 70.3 % sequence similarity, respectively. Their DNA G+C contents were 54.5-56.8 mol%. The DNA-DNA relatedness values of B. edaphicus VKPM B-7517(T) with B. mucilaginosus KNP414 and B. mucilaginosus CGMCC 1.236 were 89.2 % and 88.7 %, respectively. The major isoprenoid quinone of B. mucilaginosus and B. edaphicus was MK-7 (94.1-95.7 %). The peptidoglycan type was A1gamma (meso-diaminopimelic acid) and the major polar lipids were phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids were anteiso-C(15 : 0), C(16 : 1)omega11c and C(16 : 0). Phenotypic features and fatty acid profiles supported the similarity of B. mucilaginosus and B. edaphicus to Paenibacillus validus CCTCC 95016(T) and confirmed their relationship with members of the genus Paenibacillus. Therefore, it is proposed that Bacillus mucilaginosus and Bacillus edaphicus be transferred to the genus Paenibacillus as Paenibacillus mucilaginosus comb. nov. (type strain HSCC 1605(T)=VKPM B-7519(T)=VKM B-1480D(T)=CIP 105815(T)=KCTC 3870(T)) and Paenibacillus edaphicus comb. nov. (type strain VKPM B-7517(T)=DSM 12974(T)=CIP 105814(T)), respectively. PMID:19643872

Hu, Xiu-Fang; Li, Shi-Xiao; Wu, Jin-Guang; Wang, Jian-Feng; Fang, Qiong-Lou; Chen, Ji-Shuang

2010-01-01

452

Stabilization of a self-referenced, prism-based, Cr:forsterite laser frequency comb using an intracavity prism  

SciTech Connect

The frequency comb from a prism-based Cr:forsterite laser has been frequency stabilized using intracavity prism insertion and pump power modulation. Absolute frequency measurements of a CW fiber laser stabilized to the P(13) transition of acetylene demonstrate a fractional instability of {approx}2x10{sup -11} at a 1 s gate time, limited by a commercial Global Positioning System (GPS)-disciplined rubidium oscillator. Additionally, absolute frequency measurements made simultaneously using a second frequency comb indicate relative instabilities of 3x10{sup -12} for both combs for a 1 s gate time. Estimations of the carrier-envelope offset frequency linewidth based on relative intensity noise and the response dynamics of the carrier-envelope offset to pump power changes confirm the observed linewidths.

Tillman, Karl A.; Thapa, Rajesh; Knabe, Kevin; Wu Shun; Lim, Jinkang; Washburn, Brian R.; Corwin, Kristan L.

2009-12-20

453

All-Optical OC-192 RZ data decision gating in dark optical comb injected semiconductor optical amplifier  

NASA Astrophysics Data System (ADS)

We demonstrate a novel all-optical RZ decision gate by using one dark-optical-comb injected SOA which is controlled by a reshaped optical clock with extremely high cross-gain-modulation (XGM) depth and narrow gain window. Such a decision gate exhibits improved 3R regeneration performances including timing tolerance of 33.5 ps, Q factor of 8.1 and extinction ratio of 13.6 dB. The correlation between backward injected dark-comb and input data wavelength region for optimizing the extinction ratio of the decision gated RZ data is determined. Under a threshold operating dark-optical comb power of 7 dBm, such a decision gate can recover the degraded RZ data with a bit-error-rate of less than 10 -9 at 10 Gbits/s.

Liao, Yu-Sheng; Yu, Kun-Chieh; Lin, Gong-Ru

2006-09-01

454

Heterosexuality and Sex-Typing.  

ERIC Educational Resources Information Center

Previous research (Bem, 1976) has shown that sex-typed and androgynous persons differ in their behavior in a variety of situations. The present paper describes four studies of the relationship of sex-typing to sexual socialization and to heterosexual attitudes and behavior. This program of research indicates that persons do differ in their sexual…

Allgeier, Elizabeth R.

455

Sex Differences in Fetal Habituation  

ERIC Educational Resources Information Center

There is some evidence for sex differences in habituation in the human fetus, but it is unknown whether this is due to differences in central processing (habituation) or in more peripheral processes, sensory or motor, involved in the response. This study examined whether the sex of the fetus influenced auditory habituation at 33 weeks of…

Hepper, Peter G.; Dornan, James C.; Lynch, Catherine

2012-01-01

456

Sex Differences in Dichotic Listening  

ERIC Educational Resources Information Center

The present study quantified the magnitude of sex differences in perceptual asymmetries as measured with dichotic listening. This was achieved by means of a meta-analysis of the literature dating back from the initial use of dichotic listening as a measure of laterality. The meta-analysis included 249 effect sizes pertaining to sex differences and…

Voyer, Daniel

2011-01-01

457

Moral Pluralism and Sex Education  

ERIC Educational Resources Information Center

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…

Corngold, Josh

2013-01-01

458

Sex Differences in Nonverbal Behavior.  

ERIC Educational Resources Information Center

This study was designed to evaluate the effects of both sex of subject and sex of partner with respect to a wide variety of nonverbal behaviors. The subjects were 44 men and 44 women graduate professional students at the University of Chicago. The behaviors were coded from videotapes of 88 dyadic conversations where each subject participated in…

Beekman, Susan J.

459

Sex Steroids Modify Working Memory  

Microsoft Academic Search

In the last ten years, numerous mechanisms by which sex steroids modify cortical function have been described. For example, estrogen replacement improves verbal memory in women, and animal studies have shown effects of estrogen on hippocampal synaptogenesis and function. Little is known about sex steroid effects on other aspects of memory, such as frontal lobe-mediated working memory. We examined the

Jeri S. Janowsky; Bambi Chavez; Eric Orwoll

2000-01-01

460

Market Forces and Sex Discrimination  

Microsoft Academic Search

We report new evidence on the existence of sex discrimination in wages and whether competitive market forces reduce or eliminate discrimination, based on plant- and firm-level data on profitability, growth and ownership changes, product market power, and workforce sex composition. Our strongest finding is that among plants with high levels of product market power, those employing more women are more

Judith K. Hellerstein; David Neumark; Kenneth R. Troske

2002-01-01

461

Market Forces and Sex Discrimination  

Microsoft Academic Search

We report new evidence on the existence of sex discrimination in wages and whether competitive market forces act to reduce or eliminate discrimination. Specifically, we use plant- and firm-level data to examine the relationships between profitability, growth and ownership changes, product market power, and the sex composition of a plant's or firm's workforce. Our strongest finding is that among plants

Judith K. Hellerstein; David Neumark; Kenneth R. Troske

1998-01-01

462

Market Forces and Sex Discrimination  

Microsoft Academic Search

We report new evidence on the existence of sex discrimination in wages and whether competitive market forces act to reduce or eliminate discrimination. Specifically, we use plant- and firm-level data to examine the relationships between profitability, growth and ownership changes, product market power, and the sex composition of a plant's or firm's workforce. Our strongest finding is that among plants

Judith K. Hellerstein; David Neumark; Kenneth R. Troske

1997-01-01

463

MARKET FORCES AND SEX DISCRIMINATION  

Microsoft Academic Search

We report new evidence on the existence of sex discrimination in wages and whether competitivemarket forces act to reduce or eliminate discrimination. Specifically, we use plant- and firm-level data toexamine the relationships between profitability, growth and ownership changes, product market power, andthe sex composition of a plant's or firm's workforce. Our strongest finding is that among plants with highlevels of

Judith K. Hellerstein; David Neumark; Kenneth R. Troske

1999-01-01

464

Substance abuse among sex offenders  

Microsoft Academic Search

A total of 461 male sex offenders were compared on their histories of alcohol and street drug use. The Drug Use Survey, Michigan Alcoholism Screening Test (MAST), and Drug Abuse Screening Test (DAST) were examined to provide measures of 1) type and frequency of substance use, 2) mood on alcohol and drugs, and 3) alcoholism and drug abuse. Most sex

Ron Langevin; Reuben A. Lang

1990-01-01

465

Sex Offender Recidivism: A Review  

Microsoft Academic Search

The increasing recognition of the large number of people victimized by sexual assault has focused considerable attention on methods for deterring its perpetrators. In particular, law enforcement and mental health professions alike seek ways to prevent sex offenders from repeating their criminal behavior. Some evidence suggests sex offenders often continue offending even after incarceration or clinical treatment. However, recidivism rates

Lita Furby; Mark R. Weinrott; Lyn Blackshaw

1989-01-01

466

The trouble with sex differences.  

PubMed

Sex differences in the brain are real and clinically important but often grossly distorted in popular discourse. Considering the public's deep fascination with sex difference research and its impact on issues from mental health to education and workplace equity, neuroscientists should pay greater heed to its misappropriation and to studying how gender enculturation shapes neural function. PMID:22196326

Eliot, Lise

2011-12-22

467

Sex Chromosomes in Land Plants  

E-print Network

Sex Chromosomes in Land Plants Ray Ming,1 Abdelhafid Bendahmane,2,3 and Susanne S. Renner4 1 chromosomes, suppression of recombination Abstract Sex chromosomes in land plants can evolve as a consequence chromosomes in hepatics, mosses, and gymnosperms are morphologically heteromor- phic. In angiosperms

Renner, Susanne

468

The Consequences of Sex Selection  

ERIC Educational Resources Information Center

A group of researchers at Baylor College of Medicine in Houston are set to do a long-term study of families that would permit to select the sex of their babies through genetic testing before implanting the embryo in the mother. Technologies such as in vitro fertilization involved in selecting a baby's sex has societal and psychological…

Rothman, Barbara Katz

2006-01-01

469

Adolescent pregnancy and sex roles  

Microsoft Academic Search

Traditional sex roles are related to the occurrence of adolescent pregnancy in this study. Sex-role orientation and related variables were measured by a questionnaire administered to 161 young women aged 13 to 18 years when they sought pregnancy tests or birth control information at one of several clinics. The hypothesis of the study, that adolescents who get pregnant are more

Carol J. Ireson

1984-01-01

470

Sex research and social change  

Microsoft Academic Search

The history of scientific sex research which emerged at the turn of the century with the exemplary work of Sigmund Freud and Havelock Ellis has been complexly interactive with changing general social conditions, specific trends in sexual conduct, the content of sexual ideologies, and the developing techniques of scientific inquiry. The earliest sex researchers, although serving to bring sexuality out

John H. Gagnon

1975-01-01

471

Cascaded integrator comb filters with smoothly varying coefficients for reduced delay in synchrotron feedback loops  

NASA Astrophysics Data System (ADS)

The Rapid Cycling Synchrotron (RCS) of the J-PARC complex in Tokai, Japan, is designed to accelerate a high intensity proton beam from 181 MeV, and later 400 MeV to 3 GeV in 20 ms within the 40 ms machine cycle. The beam power up to 1 MW demands a stable beam control to avoid excessive losses and activation of the accelerator chain. The fully digital control system is based on quadrature modulation and demodulation. In the amplitude control loops standard FIR filters separate the harmonics (h=2) and (h=4) after down conversion. For the phase loops at (h=2) and (h=4), intended to damp synchrotron oscillations, the delay in a FIR filter would limit the loop stability. Cascaded integrator comb filters, also called CIC filters, provide a shorter delay because they filter the longitudinal beam signal only where it is necessary. The notches are located at multiples of the revolution frequency of the proton beam. For fixed frequency accelerator applications, digital comb filters with fixed clock frequency are widely used to improve loop stability. For variable frequency accelerator applications, as in a proton synchrotron, where the frequency swing is larger than the notch width, usually the clock frequency of the comb filter is variable and chosen to be an integer multiple of the particle revolution frequency. At J-PARC RCS, the clock frequency has to be fixed. Tracking the frequency would require a variable noninteger number of filter taps. Here we present a filter, based on the weighted output of 2 CIC filters with variable length, and one tap difference. The filter function looks like a CIC with smoothly varying coefficients, where the notches follow the revolution frequency of the proton beam. The delay of this filter is approximately half of the corresponding FIR filter, so that the phase loops have a higher stability margin.

Schnase, A.; Nomura, M.; Tamura, F.; Yamamoto, M.; Anami, S.; Ezura, E.; Hara, K.; Ohmori, C.; Takagi, A.; Yoshii, M.

2005-12-01

472

An Instrument to Measure Safer Sex Strategies Used by Male Sex Workers  

Microsoft Academic Search

Several studies have related safe sex in the commercial sex encounter to the ability of sex workers to apply specific safer sex strategies. However, no instrument has been previously available to measure these skills. The Safer-Sex Strategy Scale (SSS) was developed for such purposes. The psychometric properties (reliability and validity) were evaluated with a sample of sex workers recruited from

Rodrigo Mariño; Jan Browne; Victor Minichiello

2000-01-01

473

The joy of sex pheromones  

PubMed Central

Sex pheromones provide an important means of communication to unite individuals for successful reproduction. Although sex pheromones are highly diverse across animals, these signals fulfil common fundamental roles in enabling identification of a mating partner of the opposite sex, the appropriate species and of optimal fecundity. In this review, we synthesize both classic and recent investigations on sex pheromones in a range of species, spanning nematode worms, insects and mammals. These studies reveal comparable strategies in how these chemical signals are produced, detected and processed in the brain to regulate sexual behaviours. Elucidation of sex pheromone communication mechanisms both defines outstanding models to understand the molecular and neuronal basis of chemosensory behaviours, and reveals how similar evolutionary selection pressures yield convergent solutions in distinct animal nervous systems. EMBO reports advance online publication 13 September 2013; doi:10.1038/embor.2013.140 PMID:24030282

Gomez-Diaz, Carolina; Benton, Richard

2013-01-01

474

Sex Hormones and Immune Dimorphism  

PubMed Central

The functioning of the immune system of the body is regulated by many factors. The abnormal regulation of the immune system may result in some pathological conditions. Sex hormones of reproductive system are one of the major factors that regulate immune system due to the presence of hormone receptors on immune cells. The interaction of sex hormones and immune cells through the receptors on these cells effect the release of cytokines which determines the proliferation, differentiation, and maturation of different types of immunocytes and as a result the outcome of inflammatory or autoimmune diseases. The different regulations of sex hormones in both sexes result in immune dimorphism. In this review article the mechanism of regulation of immune system in different sexes and its impact are discussed. PMID:25478584

Bhatia, Aruna; Sekhon, Harmandeep Kaur; Kaur, Gurpreet

2014-01-01

475

Weaving quantum optical frequency combs into continuous-variable hypercubic cluster states  

NASA Astrophysics Data System (ADS)

Cluster states with higher-dimensional lattices that cannot be physically embedded in three-dimensional space have important theoretical interest in quantum computation and quantum simulation of topologically ordered condensed-matter systems. We present a simple, scalable, top-down method of entangling the quantum optical frequency comb into hypercubic-lattice continuous-variable cluster states of a size of about 104 quantum field modes, using existing technology. A hypercubic lattice of dimension D (linear, square, cubic, hypercubic, etc.) requires but D optical parametric oscillators with bichromatic pumps whose frequency splittings alone determine the lattice dimensionality and the number of copies of the state.

Wang, Pei; Chen, Moran; Menicucci, Nicolas C.; Pfister, Olivier

2014-09-01

476

Linearization of a two-axis MEMS scanner driven by vertical comb-drive actuators  

NASA Astrophysics Data System (ADS)

A driving scheme using a pair of differential voltages (Vx, Vy) over a bias voltage is proposed to linearize the dc characteristic (angle versus voltage) of a two-axis MEMS scanner. The micromirror has a gimbal-less structure and is driven by vertical comb-drive actuators in conjunction with a leverage mechanism. At an optimal bias voltage of 53 V, a linear optical scan range of ±3.2° is achieved experimentally in both the x and y directions with the differential voltages ranging from -10 V to + 10 V.

Tsai, Jui-che; Lu, Li-Cheng; Hsu, Wei-Chi; Sun, Chia-Wei; Wu, Ming C.

2008-01-01

477

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

DOEpatents

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.

Chandler, David W; Strecker, Kevin E

2014-04-01

478

Occurrence of squalene and sterols in Cellulomonas dehydrogenans (Arnaudi 1942) comb. nov. Hester 1971.  

PubMed Central

The neutral lipid fraction of the photochromogenic, coryneform bacterium Cellulomonas dehydrogenans (Arnaudi 1942) comb. nov. contains the sterol precursor squalene and at least two sterols, cholesterol and beta-sitosterol. The compounds were characterized by mass spectrometry and combination gas-liquid chromatography--mass spectrometry. De novo sterol biosynthetic ability was shown from incorporation of 14C from D-[U-14C]glucose into squalene and the sterol fraction. The squalene concentration approximated 0.002 to 0.005% of the total dry cell weight, and the sterols approximated 0.03 to 0.05%. Images PMID:101527

Weeks, O B; Francesconi, M D

1978-01-01

479

Triteleia peyerimhoffi comb. n., a remarkably variable circum-Mediterranean scelionid (Hymenoptera, Platygastroidea)  

PubMed Central

Abstract Triteleia peyerimhoffi comb. n. (Kieffer, 1906) is redescribed taking into account its great variability and is considered the senior synonym of Triteleia dubia (Kieffer, 1908), Calliscelio lugens (Kieffer, 1910) and Triteleia striolata Kononova & Petrov, 2000, syn. n. Neotypes are designated for Triteleia dubia and Triteleia peyerimhoffi. Triteleia peyerimhoffi is a new record for Greece, France and Croatia and was reared for the first time from eggs of Orthoptera laid in the dead wood of Quercus sp. and Tilia sp. in Romania. PMID:22144859

Popovici, Ovidiu Alin; Bin, Ferdinando; Masner, Lubomir; Popovici, Mariana; Notton, David

2011-01-01

480

Fabrication of a microelectromechanical directional sound sensor with electronic readout using comb fingers  

NASA Astrophysics Data System (ADS)

By emulating the hearing organ of the Ormia ochracea fly, a microelectromechanical sound sensor was fabricated which is able to determine the direction of incident sound despite an overall size much smaller than the wavelength of interest. The sensor consists of two wings that are coupled in the middle and attached to the surrounding substrate by two legs. The design incorporated interdigitated comb fingers on the wings and the substrate which enables electrostatic (capacitive) readout. Measured electrical response showed a strong dependence on the direction of incident sound.

Touse, Michael; Sinibaldi, Jose; Simsek, Kursad; Catterlin, Jeffrey; Harrison, Stephen; Karunasiri, Gamani

2010-04-01

481

Frequency-comb-referenced multi-channel fiber laser for DWDM communication.  

PubMed

We propose an all-fiber-based multi-channel optical scheme that enables simultaneous generation of multiple continuous-wave laser wavelengths with stabilization to the frequency comb of a femtosecond laser. The intention is to produce highly stable, accurate wavelength channels with immunity to environmental disturbance so as to enhance the transmission capacity of dense wavelength division multiplexing (DWDM) communications. Generated wavelengths lie over a wide spectral range of 5 THz about 1550 nm, each yielding a narrow linewidth of less than 24 kHz with an absolute position uncertainty of ~2.24 × 10¹² (10 s averaging) traceable directly to the atomic Rb clock. PMID:24514469

Chun, Byung Jae; Hyun, Sangwon; Kim, Seungman; Kim, Seung-Woo; Kim, Young-Jin

2013-12-01

482

Anxiety Correlates of Sex-Role Identity  

ERIC Educational Resources Information Center

Examines some possible relationships between sex-role identity and other factors, specifically, openness vs. closedness, liberalism vs. conservatism, and other cross-sex vs. same-sex parent identification. (Author/RK)

Biaggio, Mary Kay; Nielsen, Elwin C.

1976-01-01

483

Sex and Psychological Differentiation in Preschoolers  

ERIC Educational Resources Information Center

Examined the relationship between selected maternal attitudes and the sex, sex role preference and level of psychological differentiation of the preschool child. Data indicate that extreme sex role typing works against learning. (GO)

Domash, Leanne; Balter, Lawrence

1976-01-01

484

78 FR 23835 - Sex Offender Registration Amendments  

Federal Register 2010, 2011, 2012, 2013, 2014

...COLUMBIA 28 CFR Part 811 RIN 3225-AA10 Sex Offender Registration Amendments AGENCY...verification of registration information for sex offenders. Furthermore, the rule permits CSOSA to verify addresses of sex offenders by conducting home visits...

2013-04-23

485

Reconstructing the Evolution of Vertebrate Sex Chromosomes  

E-print Network

Sex chromosomes and their evolution have captivated researchers since their discovery. For more than 100 years, the dominant model of sex chromosome evolution has held that differentiated sex chromosomes, such as the X and ...

Bellott, Daniel W.

486

Generation of a noiselike soliton molecule induced by a comb filter in a figure-eight fiber laser  

NASA Astrophysics Data System (ADS)

We report on the generation of a noiselike soliton molecule induced by a comb filter in a figure-eight fiber laser. Despite the noiselike mode-locked operation, there were always several peaks riding on a wide shoulder when the mode-locked operation was obtained; this phenomenon was called the noiselike soliton molecule. It was found that the formation of the noiselike soliton molecule is induced by the intracavity comb filter. The observed results would give further insight towards understanding both the fundamental physics of soliton molecules and the noiselike pulses in passively mode-locked fiber lasers.

Luo, Ai-Ping; Zheng,