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1

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

2

Male- and female-specific variants of doublesex gene products have different roles to play towards regulation of Sex combs reduced expression and sex comb morphogenesis in Drosophila.  

PubMed

Sexually dimorphic characters have two-fold complexities in pattern formation as they have to get input from both somatic sex determination as well as the positional determining regulators. Sex comb development in Drosophila requires functions of the somatic sex-determining gene doublesex and the homeotic gene Sex combs reduced. Attempts have not been made to decipher the role of dsx in imparting sexually dimorphic expression of SCR and the differential function of sex-specific variants of dsx products in sex comb development. Our results in this study indicate that male-like pattern of SCR expression is independent of dsx function, and dsx F must be responsible for bringing about dimorphism in SCR expression, whereas dsx M function is required with Scr for the morphogenesis of sex comb. PMID:23938378

Devi, Thangjam Ranjita; Shyamala, B V

2013-09-01

3

Expression of the Sex combs reduced protein in Drosophila larvae.  

PubMed

We have generated a monoclonal antibody that binds specifically to the protein product of the homeotic Sex combs reduced (Scr) gene of Drosophila, and have mapped the patterns of Scr expression in late third instar larvae. Virtually the entire prothoracic leg imaginal disc expresses the gene, although the levels of expression vary in different disc regions. This heterogeneity does not reflect the compartmental domains defined by engrailed gene expression. Expression is also observed in the cells of the humeral and labial discs, and there is a small patch of Scr-expressing cells in the antenna disc. The gene is expressed in adepithelial cells of the three thoracic leg discs, but not in the wing or haltere discs. In the central nervous system, Scr expression is confined to a narrow band of cells in the subesophageal region of the ventral ganglion. The results are discussed with respect to the known genetic requirements for Scr+ function. PMID:2896135

Glicksman, M A; Brower, D L

1988-05-01

4

Evolution of the insect body plan as revealed by the Sex combs reduced expression pattern.  

PubMed

The products of the HOM/Hox homeotic genes form a set of evolutionarily conserved transcription factors that control elaborate developmental processes and specify cell fates in many metazoans. We examined the expression of the ortholog of the homeotic gene Sex combs reduced (Scr) of Drosophila melanogaster in insects of three divergent orders: Hemiptera, Orthoptera and Thysanura. Our data reflect how the conservation and variation of Scr expression has affected the morphological evolution of insects. Whereas the anterior epidermal expression of Scr, in a small part of the posterior maxillary and all of the labial segment, is found to be in common among all four insect orders, the posterior (thoracic) expression domains vary. Unlike what is observed in flies, the Scr orthologs of other insects are not expressed broadly over the first thoracic segment, but are restricted to small patches. We show here that Scr is required for suppression of wings on the prothorax of Drosophila. Moreover, Scr expression at the dorsal base of the prothoracic limb in two other winged insects, crickets (Orthoptera) and milkweed bugs (Hemiptera), is consistent with Scr acting as a suppressor of prothoracic wings in these insects. Scr is also expressed in a small patch of cells near the basitarsal-tibial junction of milkweed bugs, precisely where a leg comb develops, suggesting that Scr promotes comb formation, as it does in Drosophila. Surprisingly, the dorsal prothoracic expression of Scr is also present in the primitively wingless firebrat (Thysanura) and the leg patch is seen in crickets, which have no comb. Mapping both gene expression patterns and morphological characters onto the insect phylogenetic tree demonstrates that in the cases of wing suppression and comb formation the appearance of expression of Scr in the prothorax apparently precedes these specific functions. PMID:9006076

Rogers, B T; Peterson, M D; Kaufman, T C

1997-01-01

5

A Functional and Structural Analysis of the Sex Combs Reduced Locus of Drosophila Melanogaster  

PubMed Central

We have undertaken a developmental genetic analysis of the homeotic gene Sex combs reduced (Scr) of Drosophila melanogaster by examining embryonic and adult phenotypes of mutations affecting Scr gene function. Molecular mapping of Scr breakpoint lesions has defined a segment of >70 kb of DNA necessary for proper Scr gene function. This region is split by the fushi tarazu (ftz) gene, with lesions affecting embryonic Scr function molecularly mapping to the region proximal (5') to ftz and those exhibiting polyphasic semilethality predominantly mapping distal (3') to ftz. Gain-of-function mutations are associated with genomic rearrangements and map throughout the Scr locus. Our analysis has revealed that the Scr locus encompasses genetic elements that are responsible for functions in both the embryonic and larval to adult periods of development. From these studies, we conclude that Scr is a complex genetic locus with an extensive regulatory region that directs functions required for normal head and thoracic development in both the embryo and the adult and that the regulation of Scr during these two periods is distinct. PMID:1743486

Pattatucci, A. M.; Otteson, D. C.; Kaufman, T. C.

1991-01-01

6

The role of HOM-C genes in segmental transformations: reexamination of the Drosophila Sex combs reduced embryonic phenotype.  

PubMed

Homeotic genes in the Antennapedia Complex of Drosophila specify identity of the posterior head segments; the labial segment requires Sex combs reduced (Scr) for proper development, Deformed (Dfd) specifies maxillary and mandibular identity, and labial is necessary for intercalary segment identity. Although mutations in these genes cause homeotic transformations during imago development, the only obvious homeotic transformation during embryonic head development is found in Scr mutants, where a partial transformation of the labial segment to a more anterior, maxillary identity has been reported. This transformation is unusual because DFD protein does not accumulate in the labial cells of Scr mutants, although DFD is required for development of maxillary structures. Here, we present evidence that casts doubt on whether the labial to maxillary transformation actually exists in embryos lacking Scr. The observed morphological characteristics and gene expression patterns of various mutant embryos indicate a loss of segmental identity rather than a transformation. PMID:8948580

Pederson, J D; Kiehart, D P; Mahaffey, J W

1996-11-25

7

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

8

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

9

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

SciTech Connect

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) 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 Polycomb and trithorax group loci. 98 refs., 6 figs., 4 tabs.

Gindhart, J.G. Jr.; Kaufman, T.C. [Indiana Univ., Bloomington, IN (United States)

1995-02-01

10

The gap gene Krüppel of Rhodnius prolixus is required for segmentation and for repression of the homeotic gene sex comb-reduced.  

PubMed

The establishment of the anterior-posterior segmentation in insects requires the concerted action of a hierarchical gene network. Here, we study the orthologue of Krüppel gap gene in the hemipteran Rhodnius prolixus (Rp-Kr). We characterized its structure, expression pattern and function. The genomic sequence upstream of the Rp-Kr transcriptional unit shows a putative regulatory region conserved in the orthologue genes from Drosophila melanogaster and Tribolium castaneum. Rp-Kr expression is zygotic and it is expressed in the anterior half of the embryo (the posterior half of the egg) during the blastoderm stage and germ band formation; later, during germ band extension, it is expressed in a central domain, from T2 to A3. The Rp-Kr loss of function phenotypes shows disrupted thoracic and abdominal segmentation. Embryos with weak segmentation phenotypes show homeotic transformations, in which an ectopic tibial comb, typical of T1 leg, appears in T2, which correlates with the ectopic expression of Rp-sex-comb reduced in this leg. PMID:24406318

Lavore, Andrés; Esponda-Behrens, Natalia; Pagola, Lucía; Rivera-Pomar, Rolando

2014-03-01

11

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

12

Molecular Genetics of the Posterior Sex Combs/Suppressor 2 of Zeste Region of Drosophila: Aberrant Expression of the Suppressor 2 of Zeste Gene Results in Abnormal Bristle Development  

PubMed Central

We report the molecular characterization of the Posterior sex combs-Suppressor 2 of zeste region of Drosophila melanogaster. The distal breakpoint of the Aristapedioid inversion divides the region into two parts. We have molecularly mapped the lesions associated with several loss of function mutations in the Polycomb group gene Posterior sex combs (Psc) proximal to this breakpoint. In addition, we have found that lesions associated with several loss of function mutations in the Suppressor 2 of zeste [Su(z)2] gene lie distal to this breakpoint. Since the breakpoint does not cause a loss of function in either gene, no essential sequences are shared by these two neighboring genes. There are three dominant gain of function mutations in the region that result in abnormal bristle development. We find that all three juxtapose foreign DNA sequences upstream of the Su(z)2 gene, and that at least two of these mutations (Arp(1) and vg(D)) behave genetically as gain of function mutations in Su(z)2. Northern and in situ hybridization analyses show that the mutations result in increased accumulation of the Su(z)2 mRNA, which we argue is responsible for the bristle loss phenotype. PMID:1905661

Brunk, B. P.; Martin, E. C.; Adler, P. N.

1991-01-01

13

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

14

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

15

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

16

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

17

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

18

STATIC ELECTRICITY Plastic combs  

E-print Network

plates · Plastic lids · Unflavored gelatin powder · Long hair, fleece jacket, wool sweater..... Questions or by having them blow up a balloon and use that instead of the comb. Gelatin Stalactites 1. Pour a little of the gelatin powder on a paper plate. 2. Have the kids blow up their own balloon. 3. Rub the balloon

Benitez-Nelson, Claudia

19

Tellurium n-type doping of highly mismatched amorphous GaN1-xAsx alloys in plasma-assisted molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

In this paper we report our study on n-type Te doping of amorphous GaN1-xAsx layers grown by plasma-assisted molecular beam epitaxy. We have used a low temperature PbTe source as a source of tellurium. Reproducible and uniform tellurium incorporation in amorphous GaN1-xAsx layers has been successfully achieved with a maximum Te concentration of 9×1020 cm-3. Tellurium incorporation resulted in n-doping of GaN1-xAsx layers with Hall carrier concentrations up to 3×1019 cm-3 and mobilities of ~1 cm2/V s. The optimal growth temperature window for efficient Te doping of the amorphous GaN1-xAsx layers has been determined.

Novikov, S. V.; Ting, M.; Yu, K. M.; Sarney, W. L.; Martin, R. W.; Svensson, S. P.; Walukiewicz, W.; Foxon, C. T.

2014-10-01

20

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

21

Vertical comb array microactuators  

Microsoft Academic Search

A vertical actuator fabricated using a trench-refilled-with-polysilicon (TRiPs) process technology and employing an array of vertical oriented comb electrodes is presented. This actuator structure provides a linear drive to deflection characteristic and a large throw capability which are key features in many sensors, actuators and micromechanisms. The actuation principle and relevant theory is developed, including FastCap simulations for theoretical verification.

Arjun Selvakumar; Khalil Najafi

2003-01-01

22

Self-contacts in Asx and Glx residues of high-resolution protein structures: role of local environment and tertiary interactions.  

PubMed

In protein structures, side-chains of asparagine and aspartic acid (Asx) and glutamine and glutamic acid (Glx) can approach their own backbone nitrogen or carbonyl group. We have systematically analyzed intra-residue contacts in Asx and Glx residues and their secondary structure preferences in two different datasets consisting of 500 and 1506 high-resolution structures. Intra-residue contact in an Asx/Glx residue between the heavy atoms of side-chain and main-chain functional groups of the same residue was investigated irrespective of whether such contacts are due to hydrogen bonding or not. Our search yielded 563 and 1462 cases of self-contacting Asx and Glx residues from the two datasets. Two important observations have been made in this analysis. First, self-contacts involving side-chain oxygen and backbone nitrogen atoms in majority of Asx residues are not due to hydrogen bonds. In the second instance, surprisingly, side-chain and backbone carbonyl oxygens of a significant number of Asx and Glx residues approach each other. For a wide-range of accessible surface areas, self-contacting residues are surrounded by less number of polar groups compared to all other Asx/Glx residues. In buried and partially buried regions, side-chain and main-chain functional groups of these residues together participate in simultaneous interactions with the available polar groups or water molecules. Asx/Glx residues with self-contacts are rarely observed in the middle of an alpha-helix or a beta-strand. Asx/Glx side-chain having contact with its own backbone nitrogen shows different capping preferences compared to those having contact with its backbone oxygen. Examples of proteins with multiple self-contacting Asx/Glx residues are found. We speculate that mutation of a self-contacting residue in the buried or partially buried region of a protein will destabilize the structure. The results of this analysis will help in engineering protein structures and site-directed mutagenesis experiments. PMID:18343699

Pal, Tuhin Kumar; Sankararamakrishnan, Ramasubbu

2008-08-01

23

Frequency Combs 250 Special Topics  

E-print Network

Frequency Combs 250 Special Topics Jennie Guzman 1 #12;Frequency Comb http://www.nist crystal 3 #12;Kerr Effect ·Index of refraction is proportional to intensity ·Kerr medium acts like a lens:sapphire laser Output Coupler Pump Ti: sapphire crystal 6 #12;Dispersion ·Spectral dispersion due to variation

Budker, Dmitry

24

Laser Spectroscopy and Frequency Combs  

NASA Astrophysics Data System (ADS)

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

Hänsch, Theodor W.; Picqué, Nathalie

2013-12-01

25

Spatial patterns in the brood combs of Nannotrigona testaceicornis (Hymenoptera: Meliponinae): male clusters.  

PubMed

Genetic models of sex and caste determination in eusocial stingless bees suggest specific patterns of male, worker and gyne cell distribution in the brood comb. Conflict between queen and laying workers over male parentage and center-periphery gradients of conditions, such as food and temperature, could also contribute to non-random spatial configuration. We converted the positions of the hexagonal cells in a brood comb to Cartesian coordinates, labeled by sex or caste of the individuals inside. To detect and locate clustered patterns, the mapped brood combs were evaluated by indexes of dispersion (MMC, mean distance of cells of a given category from their centroid) and eccentricity (DMB, distance between this centroid and the overall brood comb centroid) that we developed. After randomizing the labels and recalculating the indexes, we calculated probabilities that the original values had been generated by chance. We created sets of binary brood combs in which males were aggregated, regularly or randomly distributed among females. These stylized maps were used to describe the power of MMC and DMB, and they were applied to evaluate the male distribution in the sampled Nannotrigona testaceicornis brood combs. MMC was very sensitive to slight deviations from a perfectly rounded clump; DMB detected any asymmetry in the location of these compact to fuzzy clusters. Six of the 82 brood combs of N. testaceicornis that we analyzed had more than nine males, distributed according to variations in spatial patterns, as indicated by the two indexes. PMID:19551646

Eterovic, A; Cabral, G C P; Oliveira, A A; Imperatriz-Fonseca, V L; Santos-Filho, P S

2009-01-01

26

Towards VECSEL frequency combs  

NASA Astrophysics Data System (ADS)

Significant progress has been made over the last year towards generating frequency combs using VECSELs. Here, I will discuss recent progress made generating < 4kW peak power femtosecond pulse VECSELs, where we have achieved 3.3 W average power with 400 fs pulse duration at 1.7 GHz repetition rate. This has been achieved by exploiting the rapid power scaling progress made in the field of CW VECSELs [1]. The gain structure used here is grown and processed by the University of Marburg, and the window layer is etched for anti-resonance to increase the gain bandwidth and reduce the dispersion [2]. We have used this to generate supercontinuum, achieving 45 % throughput in a 2.2 micron core photonic crystal fiber when the VECSEL produced 1 W average output power. A continuum with a width of 175 nm is generated. At higher average powers heating of the fiber tip reduces coupling efficiency which limits the supercontinuum bandwidth and we will discuss measures to avoid this. Finally, I will outline approaches to further reduce the pulse length, whilst maintaining the average power, to a point where generating coherent octave spanning supercontinuum, suitable for F-2F stabilization should become a reality.

Wilcox, Keith G.

2013-02-01

27

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

28

Lossless equalization of frequency combs.  

PubMed

Frequency combs obtained by sinusoidal phase modulation of narrowband cw lasers are widely used in the field of optical communications. However, the resulting spectral envelope of the comb is not flat. We propose a general and efficient approach to achieve flat frequency combs with tunable bandwidth. The idea is based on a two-step process. First, efficient generation of a train with a temporal flat-top-pulse profile is required. Second, we use large parabolic phase modulation in every train period to map the temporal intensity shape into the spectral domain. In this way the resulting spectral envelope is flat, and the size is tunable with the chirping rate. Two different schemes are proposed and verified through numerical simulations. PMID:18709099

Torres-Company, Víctor; Lancis, Jesús; Andrés, Pedro

2008-08-15

29

A Josephson radiation comb generator  

E-print Network

Optical frequency combs have been a major research trend of the last decade [1]. The possibility to generate higher harmonics starting from a fundamental one has made it possible to extend the accuracy of the atomic clocks from the radio to the optical frequency region, leading to breakthroughs in optical metrology [2], high precision spectroscopy [3, 4] and telecommunication technologies [1, 5]. Here we show that a similar-in-spirit harmonic generator can be implemented with a dc superconducting quantum interference device (SQUID) subject to a time-dependent magnetic field. Driven by the field, the superconducting phase difference across the SQUID undergoes jumps of $\\pi$, which are associated to a sequence of sharp, evenly spaced voltage pulses. This pulse sequence translates into a radiation comb in frequency domain, thereby realizing a Josephson radiation comb generator (JRCG). Under suitable conditions, the JRCG can provide up to several hundreds of harmonics of the driving frequency. For example, a chain of $10^4$ identical high-critical-temperature SQUIDs driven at 1 GHz can deliver up to a few tens nW at 500 GHz. The availability of a fully solid-state radiation comb generator such as the JRCG, easily integrable on chip, will pave the way to a number of technological applications, from metrology to sub-millimeter wave generation.

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

2014-10-29

30

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

31

Femtosecond laser comb based subterahertz synthesizer  

NASA Astrophysics Data System (ADS)

Functioning layout of a frequency comb-based subterahertz synthesizer is demonstrated. A primary subterahertz oscillator was phase-locked against the Ti:Sapphire femtosecond laser frequency comb down-converted to the subterahertz range by the semiconductor mixer. Synthesizer operation is demonstrated through Fabri-Perot resonator response curve recording experiment. Spectral purity of the synthesizer was estimated. The advantage of the comb-based synthesizer over the synthesizer based on the Agilent E8257D device was shown.

Makarov, D. S.; Tretyakov, M. Yu.; Shkaev, A. P.; Kiselev, A. M.; Stepanov, A. N.; Parshin, V. V.

2014-08-01

32

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

33

Evolution of Sex-Specific Traits through Changes in HOX-Dependent doublesex Expression  

PubMed Central

Almost every animal lineage is characterized by unique sex-specific traits, implying that such traits are gained and lost frequently in evolution. However, the genetic mechanisms responsible for these changes are not understood. In Drosophila, the activity of the sex determination pathway is restricted to sexually dimorphic tissues, suggesting that spatial regulation of this pathway may contribute to the evolution of sex-specific traits. We examine the regulation and function of doublesex (dsx), the main transcriptional effector of the sex determination pathway, in the development and evolution of Drosophila sex combs. Sex combs are a recent evolutionary innovation and show dramatic diversity in the relatively few Drosophila species that have them. We show that dsx expression in the presumptive sex comb region is activated by the HOX gene Sex combs reduced (Scr), and that the male isoform of dsx up-regulates Scr so that both genes become expressed at high levels in this region in males but not in females. Precise spatial regulation of dsx is essential for defining sex comb position and morphology. Comparative analysis of Scr and dsx expression reveals a tight correlation between sex comb morphology and the expression patterns of both genes. In species that primitively lack sex combs, no dsx expression is observed in the homologous region, suggesting that the origin and diversification of this structure were linked to the gain of a new dsx expression domain. Two other, distantly related fly lineages that independently evolved novel male-specific structures show evolutionary gains of dsx expression in the corresponding tissues, where dsx may also be controlled by Scr. These findings suggest that changes in the spatial regulation of sex-determining genes are a key mechanism that enables the evolution of new sex-specific traits, contributing to some of the most dramatic examples of phenotypic diversification in nature. PMID:21886483

Tanaka, Kohtaro; Barmina, Olga; Sanders, Laura E.; Arbeitman, Michelle N.; Kopp, Artyom

2011-01-01

34

Evolution of sex-specific traits through changes in HOX-dependent doublesex expression.  

PubMed

Almost every animal lineage is characterized by unique sex-specific traits, implying that such traits are gained and lost frequently in evolution. However, the genetic mechanisms responsible for these changes are not understood. In Drosophila, the activity of the sex determination pathway is restricted to sexually dimorphic tissues, suggesting that spatial regulation of this pathway may contribute to the evolution of sex-specific traits. We examine the regulation and function of doublesex (dsx), the main transcriptional effector of the sex determination pathway, in the development and evolution of Drosophila sex combs. Sex combs are a recent evolutionary innovation and show dramatic diversity in the relatively few Drosophila species that have them. We show that dsx expression in the presumptive sex comb region is activated by the HOX gene Sex combs reduced (Scr), and that the male isoform of dsx up-regulates Scr so that both genes become expressed at high levels in this region in males but not in females. Precise spatial regulation of dsx is essential for defining sex comb position and morphology. Comparative analysis of Scr and dsx expression reveals a tight correlation between sex comb morphology and the expression patterns of both genes. In species that primitively lack sex combs, no dsx expression is observed in the homologous region, suggesting that the origin and diversification of this structure were linked to the gain of a new dsx expression domain. Two other, distantly related fly lineages that independently evolved novel male-specific structures show evolutionary gains of dsx expression in the corresponding tissues, where dsx may also be controlled by Scr. These findings suggest that changes in the spatial regulation of sex-determining genes are a key mechanism that enables the evolution of new sex-specific traits, contributing to some of the most dramatic examples of phenotypic diversification in nature. PMID:21886483

Tanaka, Kohtaro; Barmina, Olga; Sanders, Laura E; Arbeitman, Michelle N; Kopp, Artyom

2011-08-01

35

Sonic Hedgehog-Signalling Patterns the Developing Chicken Comb as Revealed by Exploration of the Pea-comb Mutation  

PubMed Central

The genetic basis and mechanisms behind the morphological variation observed throughout the animal kingdom is still relatively unknown. In the present work we have focused on the establishment of the chicken comb-morphology by exploring the Pea-comb mutant. The wild-type single-comb is reduced in size and distorted in the Pea-comb mutant. Pea-comb is formed by a lateral expansion of the central comb anlage into three ridges and is caused by a mutation in SOX5, which induces ectopic expression of the SOX5 transcription factor in mesenchyme under the developing comb. Analysis of differential gene expression identified decreased Sonic hedgehog (SHH) receptor expression in Pea-comb mesenchyme. By experimentally blocking SHH with cyclopamine, the wild-type single-comb was transformed into a Pea-comb-like phenotype. The results show that the patterning of the chicken comb is under the control of SHH and suggest that ectopic SOX5 expression in the Pea-comb change the response of mesenchyme to SHH signalling with altered comb morphogenesis as a result. A role for the mesenchyme during comb morphogenesis is further supported by the recent finding that another comb-mutant (Rose-comb), is caused by ectopic expression of a transcription factor in comb mesenchyme. The present study does not only give knowledge about how the chicken comb is formed, it also adds to our understanding how mutations or genetic polymorphisms may contribute to inherited variations in the human face. PMID:23227218

Boije, Henrik; Harun-Or-Rashid, Mohammad; Lee, Yu-Jen; Imsland, Freyja; Bruneau, Nicolas; Vieaud, Agathe; Gourichon, David; Tixier-Boichard, Michèle; Bed’hom, Bertrand; Andersson, Leif; Hallböök, Finn

2012-01-01

36

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

37

Long term comparison of two fiber based frequency comb systems  

NASA Astrophysics Data System (ADS)

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.

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

2005-02-01

38

Ultrabroadband coherent supercontinuum frequency comb  

SciTech Connect

We present detailed studies of the coherence properties of an ultrabroadband supercontinuum, enabled by a comprehensive approach involving continuous-wave laser sources to independently probe both the amplitude and phase noise quadratures across the entire spectrum. The continuum coherently spans more than 1.5 octaves, supporting Hz-level comparison of ultrastable lasers at 698 nm and 1.54 {mu}m. We present a complete numerical simulation of the accumulated comb coherence in the limit of many pulses, in contrast to the single-pulse level, with systematic experimental verification. The experiment and numerical simulations reveal the presence of quantum-seeded broadband amplitude noise without phase coherence degradation, including the discovery of a dependence of the supercontinuum coherence on the fiber fractional Raman gain.

Ruehl, Axel; McKay, Hugh; Thomas, Brian; Dong, Liang; Fermann, Martin E.; Hartl, Ingmar [IMRA America Inc., 1044 Woodridge Avenue, Ann Arbor, Michigan 48105 (United States); Martin, Michael J.; Cossel, Kevin C.; Chen Lisheng; Benko, Craig; Ye Jun [JILA, National Institute of Standards and Technology and University of Colorado, Department of Physics, 440 UCB, Boulder, Colorado 80309 (United States); Dudley, John M. [Institute FEMTO-ST, CNRS-University of Franche-Comte UMR 6174, Besancon (France)

2011-07-15

39

Electrostatic Comb Drive Levitation And Control Method  

Microsoft Academic Search

Abstmct-This paper presents the theory, slmulatlon results, and experimental study of the levitating force (normal to the substr8te) assoc&led with interdigitated capacitor (cleetrostatk comb) Inter81 actuators. For compliant suspensions, normal displacements of over 2 pm for 8 comb bias of 30 V are observed. This phenomenon is due to electrostatic attractkm induced on top of the suspended structure. By electrically

William C. Tang; Martin G. Lim; Roger T. Howe

1992-01-01

40

Phase Steps and Hot Resonator Detuning in Microresonator Frequency Combs  

E-print Network

Experiments and theoretical modeling yielded significant progress towards understanding of Kerr-effect induced optical frequency comb generation in microresonators. However, the simultaneous 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 modeling 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 {\\pi} and {\\pi}/2 steps in the comb phases that are not observed in conventional optical frequency combs.

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

2014-01-01

41

Phase steps and resonator detuning measurements in microresonator frequency combs  

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

42

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

43

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

44

Ultrasonic comb transducer for smart materials  

NASA Astrophysics Data System (ADS)

Installation of a small multi-element comb type ultrasonic transducer is proposed as a component of a smart structure. It can be used in either an active or passive mode in carrying out ultrasonic bulk or guided wave nondestructive evaluation. Theoretical methods are developed and experimental results are presented for guided wave generation and mode control with this very efficient and versatile novel comb type ultrasonic transducer. Excitation and probe design is crucial in mode selection. The comb transducer generates waves that are influenced by such parameters as number of elements, spacing between elements, dimension, pulsing sequence, and pressure distribution. The excited elastic field depends on the excitation frequency, plate thickness, and elastic properties. Techniques are studied to optimize the applied loading and the comb transducer design parameters so that only modes that are most sensitive to particular material characteristics can be generated. Complete understanding of the comb transducer parameters and their impact on the elastic field allows us to efficiently generate higher order modes as well as low phase velocity modes which are valuable in composite material characterization. Sample experiments are presented for various plate and tube like structures.

Rose, J. L.

1998-04-01

45

Wax combs mediate nestmate recognition by guard honeybees  

E-print Network

Wax combs mediate nestmate recognition by guard honeybees PATRIZIA D'ETTORRE*, TOM WENSELEERS 2006; MS. number: 8465) Research has shown that the wax combs are important in the acquisition in the laboratory or under artificial conditions. We investigated the role of the wax combs in nestmate recognition

Wenseleers, Tom

46

Highly selective terahertz optical frequency comb generator.  

PubMed

Using a 10.5-GHz resonant electro-optic modulator placed inside a resonant optical cavity, we generated an optical frequency comb with a span wider than 3 THz. The optical resonator consists of three mirrors, with the output coupler being a thin Fabry-Perot cavity with a free spectral range of 2 THz and a finesse of 400. Tuning this filter cavity onto resonance with a particular high-order sideband permits efficient output coupling of the desired sideband power from the comb generator, while keeping all other sidebands inside for continued comb generation. This spectrally pure output light was then heterodyne detected by another laser with a frequency offset of the order of 1 THz. PMID:18183182

Ye, J; Ma, L S; Daly, T; Hall, J L

1997-03-01

47

Frequency comb generation in quadratic nonlinear media  

E-print Network

Optical frequency combs are nowadays routinely used tools in a wide range of scientific and technological applications. Different techniques have been developed for generating optical frequency combs, like mode-locking in lasers and third-order interactions in microresonators, or to extend their spectral capabilities, using frequency conversion processes in nonlinear materials. Here, we experimentally demonstrate and theoretically explain the onset of optical frequency combs in a simple cavity-enhanced second-harmonic-generation system, exploiting second-order nonlinear interactions. We develop an elemental model which provides a deep physical insight into the observed dynamics. Moreover, despite the different underlying physical mechanism, the proposed model is remarkably similar to the description of third-order effects in microresonators, revealing a potential variety of new effects to be explored. Finally, exploiting a nonlinearity intrinsically stronger than the third-order one, our work lays the groundw...

Ricciardi, Iolanda; Parisi, Maria; Maddaloni, Pasquale; Santamaria, Luigi; De Natale, Paolo; De Rosa, Maurizio

2014-01-01

48

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

49

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

50

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

51

Midinfrared frequency combs from coherent supercontinuum in  

E-print Network

Midinfrared frequency combs from coherent supercontinuum in chalcogenide and optical parametric of the supercontinuum generated in a nanospike chalcogenide-silica hybrid waveguide pumped at 2 m. The supercontinuum oscillators (OPOs), micro- resonators, and supercontinuum generation. In the latter case, as long

52

Comb-drive actuators for large displacements  

Microsoft Academic Search

The design, fabrication and experimental results of lateral-comb-drive actuators for large displacements at low driving voltages is presented. A comparison of several suspension designs is given, and the lateral large deflection behaviour of clamped - clamped beams and a folded flexure design is modelled. An expression for the axial spring constant of folded flexure designs including bending effects from lateral

Rob Legtenberg; A. W. Groeneveld; M. Elwenspoek

1996-01-01

53

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 ...

54

Coherence and incoherence in an optical comb.  

PubMed

We demonstrate a coexistence of coherent and incoherent modes in the optical comb generated by a passively mode-locked quantum dot laser. This is experimentally achieved by means of optical linewidth, radio frequency spectrum, and optical spectrum measurements and confirmed numerically by a delay-differential equation model showing excellent agreement with the experiment. We interpret the state as a chimera state. PMID:24949771

Viktorov, Evgeny A; Habruseva, Tatiana; Hegarty, Stephen P; Huyet, Guillaume; Kelleher, Bryan

2014-06-01

55

Molecular Excitation at high z Franoise Combes  

E-print Network

Molecular Excitation at high z Françoise Combes Paris Observatory, LERMA Z-machines, January 2006 Black-body Tdust 4 - Tbg 4 = cste or optically thin dust ~ 2 Tdust 6 - Tbg 6 = cste #12;13 Model ·Hierarchical theory of galaxy formation Ho = 70km/s/Mpc, with =0.3 =0.7 ·Number of mergers (z) from Press

Groppi, Christopher

56

Vacuum operation of comb-drive micro display mirrors  

Microsoft Academic Search

In this study, we investigate operation characteristics of a comb-drive torsion micro-mirror in vacuum. Three types of the micro-mirror of diameter 420 µm have been designed and fabricated for resonant operation at a high frequency suitable for laser scanning display. The first type (type I) is a conventional comb-drive micro-mirror with the comb fingers installed on both sides of torsion

Chu Hoang Manh; Kazuhiro Hane

2009-01-01

57

Journal of Apicultural Research 40(1): 0000 (2001) 2001 IBRA This research examined the effects of comb age  

E-print Network

the effects of comb age on honey bee colony growth and brood sur- vivorship. Experimental old combs were of an unknown age, but were dark and heavy as typ- ical of combs one or more years old. New combs were produced variable significantly higher in old comb. Keywords: honey bees, Apis mellifera, beeswax, comb age, old

Delaplane, Keith S.

58

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

59

Photonic generation of linearly chirped millimeter wave based on comb-spacing tunable optical frequency comb  

NASA Astrophysics Data System (ADS)

We demonstrated a photonic approach to generate a phase-continuous frequency-linear-chirped millimeter-wave (mm-wave) signal with high linearity based on continuous-wave phase modulated optical frequency comb and cascaded interleavers. Through linearly sweeping the frequency of the radio frequency (RF) driving signal, high-order frequency-linear-chirped optical comb lines are generated and then extracted by the cascaded interleavers. By beating the filtered high-order comb lines, center frequency and chirp range multiplied linear-chirp microwave signals are generated. Frequency doubled and quadrupled linear-chirp mm-wave signals of range 48.6 to 52.6 GHz and 97.2 to 105.2 GHz at chirp rates of 133.33 and 266.67 GHz/s are demonstrated with the ±1st and ±2nd optical comb lines, respectively, while the RF driving signal is of chirp range 24.3 to 26.3 GHz and chirp time 30 ms.

Xia, Zongyang; Xie, Weilin; Sun, Dongning; Shi, Hongxiao; Dong, Yi; Hu, Weisheng

2013-12-01

60

Optimization of filtering schemes for broadband astro-combs  

E-print Network

line spacing; (2) power amplifiers to boost the power of pulses from the filtered comb; and (3) highlyOptimization of filtering schemes for broadband astro-combs Guoqing Chang,1,2,* Chih-Hao Li,3 David, Harvard University, Cambridge Massachusetts 02138, USA *guoqing@mit.edu Abstract: To realize a broadband

Walsworth, Ronald L.

61

An improved Combes-Thomas estimate of magnetic Schrödinger operators  

NASA Astrophysics Data System (ADS)

In the present paper, we prove an improved Combes-Thomas estimate, viz. the Combes-Thomas estimate in trace-class norms, for magnetic Schrödinger operators under general assumptions. In particular, we allow for unbounded potentials. We also show that for any function in the Schwartz space on the reals the operator kernel decays, in trace-class norms, faster than any polynomial.

Shen, Zhongwei

2014-10-01

62

COMB: A Portable Benchmark Suite for Assessing MPI Overlap  

Microsoft Academic Search

This paper describes a portable benchmark suite that as- sesses the ability of cluster networking hardware and soft- ware to overlap MPI communication and computation. The Communication Offload MPI-based Benchmark, or COMB, uses two methods to characterize the ability of messages to make progress concurrently with computational process- ing on the host processor(s). COMB measures the relation- ship between MPI

William Lawry; Christopher Wilson; Arthur B. Maccabe; Ron Brightwell

2002-01-01

63

Optical frequency comb with submillihertz linewidth and more than  

E-print Network

,3 and extreme ultraviolet comb generation experiments4,5 can find a powerful solution in fibre-based modeOptical frequency comb with submillihertz linewidth and more than 10 W average power T. R. SCHIBLI1, University of Colorado, Boulder, Colorado 80309-0440, USA 2 IMRA America, 1044 Woodridge Avenue, Ann Arbor

64

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

65

A phase-stabilized carbon nanotube fiber laser frequency comb  

E-print Network

A phase-stabilized carbon nanotube fiber laser frequency comb Jinkang Lim1 , Kevin Knabe1 , Karl A by a 167 MHz repetition frequency erbium-doped fiber ring laser using a carbon nanotube saturable absorber error on the carrier envelope offset frequency of 0.35 radians. The carbon nanotube fiber laser comb

Washburn, Brian

66

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

67

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

68

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

69

Native Chemical Ligation at Asx-Cys, Glx-Cys: Chemical Synthesis and High Resolution X-ray Structure of ShK Toxin by Racemic Protein Crystallography  

PubMed Central

We have re-examined the utility of native chemical ligation at ?Gln/Glu-Cys? [Glx-Cys] and ?Asn/Asp-Cys? [Asx-Cys] sites. Using the improved thioaryl catalyst 4-mercaptophenylacetic acid (MPAA), native chemical ligation could be performed at ?Gln-Cys? and Asn-Cys? sites without side reactions. After optimization, ligation at a ?Glu-Cys? could also be used as a ligation site, with minimal levels of byproduct formation. However, ?Asp-Cys? is not appropriate for use as a site for native chemical ligation because of formation of significant amounts of ?-linked byproduct. The feasibility of native chemical ligation at ?Gln-Cys? enabled a convergent total chemical synthesis of the enantiomeric forms of the ShK toxin protein molecule. The D-ShK protein molecule was ~50,000-fold less active in blocking the Kv1.3 channel than the L-ShK protein molecule. Racemic protein crystallography was used to obtain high resolution X-ray diffraction data for ShK toxin. The structure was solved by direct methods and showed significant differences from the previously reported NMR structures in some regions of the ShK protein molecule. PMID:23919482

Dang, Bobo; Kubota, Tomoya; Mandal, Kalyaneswar; Bezanilla, Francisco; Kent, Stephen B. H.

2013-01-01

70

Tellurium Speciation, Connectivity, and Chemical Order in AsxTe100-x Glasses: Results from Two-Dimensional (125)Te NMR Spectroscopy.  

PubMed

The short-range structure, connectivity, and chemical order in AsxTe100-x (25 ? x ? 65) glasses are studied using high-resolution two-dimensional projection magic-angle-turning (pjMAT) (125)Te nuclear magnetic resonance (NMR) spectroscopy. The (125)Te pjMAT NMR results indicate that the coordination of Te atoms obeys the 8-N coordination rule over the entire composition range. However, in strong contrast with the analogous glass-forming As-S and As-Se chalcogenides, significant violation of chemical order is observed in As-Te glasses over the entire composition range in the form of homopolar As-As (Te-Te) bonds, even in severely As (Te)-deficient glasses. The speciation of the Te coordination environments can be explained with the dissociation reaction model As2Te3 ? 2As + 3Te(II), characterized by a dissociation constant that is independent of glass composition. These structural characteristics can be attributed to the high metallicity of Te and the strong energetic similarity between the Te-Te, Te-As, and As-As bonds, and they are consistent with the monotonic and often nearly linear variation of physical properties observed in telluride glasses as a function of the Te content. PMID:25584635

Kaseman, Derrick C; Hung, Ivan; Lee, Kathleen; Kovnir, Kirill; Gan, Zhehong; Aitken, Bruce; Sen, Sabyasachi

2015-02-01

71

Theory for direct frequency-comb spectroscopy  

SciTech Connect

Direct frequency-comb spectroscopy is a technique that employs a train of well-stabilized ultrashort pulses to study the spectral properties of atomic or molecular systems. In this way, it opens the possibility of incorporating various coherent-control techniques for such spectral investigations. Here we introduce a theory for the interaction of a multilevel atom with such pulse trains, which is general enough to take into account an arbitrarily shaped frequency comb. We illustrate its application by studying the interaction of {sup 87}Rb atoms with trains of pulses of various shapes, resonant with the 5S-5D two-photon transition of rubidium. More specifically, we treat the interaction with hyperbolic-secant pulses, chirped pulses, and 0-{pi} pulses, respectively. The theory is designed to work at an arbitrary perturbation order. For the results presented here, we mostly used a 12th-order perturbation series at the pulse's electric field. Due to the large number of levels involved, such modeling may be quite complex computationally, and an important point of the present work is then to introduce the required numerical approach to treat this problem efficiently.

Felinto, Daniel; Lopez, Carlos E. E. [Departamento de Fisica, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)

2009-07-15

72

Broadband phase noise suppression in a Yb-fiber frequency comb  

E-print Network

Broadband phase noise suppression in a Yb-fiber frequency comb A. Cingöz,1, * D. C. Yost,1 T. K operation and high average power [4,5]. One of the most important applications of frequency combs has been combs with sub- hertz linewidths [6] and Yb combs with submillihertz line- widths [4], suitable

73

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

74

Versatile and Sensitive Dual Comb Fourier Transform Spectroscopy  

NASA Astrophysics Data System (ADS)

Fourier transform spectroscopy based on time-domain interferences between two slightly detuned frequency comb sources holds much promise for the real-time diagnostic of gaseous, liquid or solid-state samples. In one very recent example, cavity-enhanced absorption spectroscopy with two infrared frequency combs has demonstrated a dramatically enhanced sensitivity, compared to conventional Fourier spectroscopy, with intriguing implications for instantaneous trace gas analysis. It however remains challenging to match continuously the comb and cavity modes across a broad spectral bandwidth during the time of a measurement. An obvious alternative for reaching a long interaction path is a conventional multipass cell. Additionally, differential detection schemes may be devised to increase the dynamic range of the interferometric measurements, thus providing enhanced signal to noise ratio. Experimental demonstrations will be given in the 1.5 ?m region with a dual comb set-up based on two Er-doped fiber femtosecond lasers. The versatility and performances of these solutions will be compared to the cavity-enhanced dual comb technique and other state-of-the-art alternatives. P. Jacquet, J. Mandon, B. Bernhardt, R. Holzwarth, G. Guelachvili, T. W. Hänsch, N. Picqué, Frequency Comb Fourier Transform Spectroscopy with kHz Optical Resolution, The Optical Society of America, Washington, DC 2009, paper FMB2 (2009). B. Bernhardt, A. Ozawa, P. Jacquet, M. Jacquey, Y. Kobayashi, T. Udem, R. Holzwarth, G. Guelachvili, T.W. Hänsch, N. Picqué, Cavity-enhanced dual-comb spectroscopy, Nature Photonics 4, 55-57 (2010),

Jacquey, M.; Jacquet, P.; Mandon, J.; Thon, R.; Guelachvili, G.; Hänsch, T. W.; Picqué, N.

2010-06-01

75

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

76

A phase-stabilized carbon nanotube fiber laser frequency comb.  

PubMed

A frequency comb generated by a 167 MHz repetition frequency erbium-doped fiber ring laser using a carbon nanotube saturable absorber is phase-stabilized for the first time. Measurements of the in-loop phase noise show an integrated phase error on the carrier envelope offset frequency of 0.35 radians. The carbon nanotube fiber laser comb is compared with a CW laser near 1533 nm stabilized to the nu(1) + nu(3) overtone transition in an acetylene-filled kagome photonic crystal fiber reference, while the CW laser is simultaneously compared to another frequency comb based on a Cr:Forsterite laser. These measurements demonstrate that the stability of a GPS-disciplined Rb clock is transferred to the comb, resulting in an upper limit on the locked comb's frequency instability of 1.2 x 10(-11) in 1 s, and a relative instability of <3 x 10(-12) in 1 s. The carbon nanotube laser frequency comb offers much promise as a robust and inexpensive all-fiber frequency comb with potential for scaling to higher repetition frequencies. PMID:19654821

Lim, Jinkang; Knabe, Kevin; Tillman, Karl A; Neely, William; Wang, Yishan; Amezcua-Correa, Rodrigo; Couny, François; Light, Philip S; Benabid, Fetah; Knight, Jonathan C; Corwin, Kristan L; Nicholson, Jeffrey W; Washburn, Brian R

2009-08-01

77

Nonlinear conversion efficiency in Kerr frequency comb generation.  

PubMed

We analytically and numerically investigate the nonlinear conversion efficiency in ring microresonator-based mode-locked frequency combs under different dispersion conditions. Efficiency is defined as the ratio of the average round trip energy values for the generated pulse(s) to the input pump light. We find that the efficiency degrades with growth of the comb spectral width and is inversely proportional to the number of comb lines. It depends on the cold-cavity properties of a microresonator only and can be improved by increasing the coupling coefficient. Also, it can be increased in the multi-soliton state. PMID:25361295

Bao, Changjing; Zhang, Lin; Matsko, Andrey; Yan, Yan; Zhao, Zhe; Xie, Guodong; Agarwal, Anuradha M; Kimerling, Lionel C; Michel, Jurgen; Maleki, Lute; Willner, Alan E

2014-11-01

78

Third-order chromatic dispersion stabilizes Kerr frequency combs.  

PubMed

Using numerical simulations of an extended Lugiato-Lefever equation we analyze the stability and nonlinear dynamics of Kerr frequency combs generated in microresonators and fiber resonators, taking into account third-order dispersion effects. We show that cavity solitons underlying Kerr frequency combs, normally sensitive to oscillatory and chaotic instabilities, are stabilized in a wide range of parameter space by third-order dispersion. Moreover, we demonstrate how the snaking structure organizing compound states of multiple cavity solitons is qualitatively changed by third-order dispersion, promoting an increased stability of Kerr combs underlined by a single cavity soliton. PMID:24978250

Parra-Rivas, Pedro; Gomila, Damià; Leo, François; Coen, Stéphane; Gelens, Lendert

2014-05-15

79

Optical-frequency-comb based interrogation of fiber resonators  

NASA Astrophysics Data System (ADS)

Strain sensing at the 10-13 level, from the mHz to the kHz frequency range, is performed using a fiber Bragggrating resonator interrogated by an optical-frequency-comb stabilized laser. The optical-comb synthesizer is a fs-pulsed fiber laser phase-locked to a quartz oscillator, which provides for a very high laser-frequency stability. The comb teeth span over the 1510-1580 nm spectral interval. Therefore, the OFS is also used as a coherent radiation source for fiber-loop cavity ring-down evanescent-wave spectroscopy of analytes diluted in liquid samples.

Gagliardi, G.; Avino, S.; Fabian, M.; Salza, M.; Ferraro, P.; De Natale, P.

2011-05-01

80

Ultra-Broadband Coherent Supercontinuum Frequency Comb  

E-print Network

We present detailed studies of the coherence properties of an ultra-broadband super-continuum, enabled by a new approach involving continuous wave laser sources to independently probe both the amplitude and phase noise quadratures across the entire spectrum. The continuum coherently spans more than 1.5 octaves, supporting Hz-level comparison of ultrastable lasers at 698 nm and 1.54 {\\mu}m. We present the first numerical simulation of the accumulated comb coherence in the limit of many pulses, in contrast to the single-pulse level, with systematic experimental verification. The experiment and numerical simulations reveal the presence of quantum-seeded broadband amplitude noise without phase coherence degradation, including the discovery of a dependence of the super-continuum coherence on the fiber fractional Raman gain.

Ruehl, Axel; Cossel, Kevin C; Chen, Lisheng; McKay, Hugh; Thomas, Brian; Benko, Craig; Dong, Liang; Dudley, John M; Fermann, Martin E; Hartl, Ingmar; Ye, Jun

2011-01-01

81

Storage and Release of a Sex Pheromone by the Queensland Fruit Fly, Dacus tryoni (Diptera: Trypetidae)  

Microsoft Academic Search

Dacus tryoni (Frogg.) mates at dusk. During courtship, males stridulate by drawing their wings across a pair of combs formed from large bristles on the third abdominal tergite. This produces a high pitched buzz, audible to the human ear, which is considered to be a mating call1. It has now been demonstrated that the male also produces a sex pheromone

B. S. Fletcher

1968-01-01

82

Ramsey-comb spectroscopy with intense ultrashort laser pulses  

NASA Astrophysics Data System (ADS)

Optical frequency combs based on mode-locked lasers have revolutionized the field of metrology and precision spectroscopy by providing precisely calibrated optical frequencies and coherent pulse trains. Amplification of the pulsed output from these lasers is very desirable, as nonlinear processes can then be used to cover a much wider range of transitions and wavelengths for ultra-high precision, direct frequency comb spectroscopy. Therefore full repetition rate laser amplifiers and enhancement resonators have been employed to produce up to microjoule-level pulse energies. Here we present a spectroscopic method to obtain frequency comb accuracy and resolution by using only two frequency comb pulses amplified to the millijoule pulse energy level, orders of magnitude more energetic than what has previously been possible. The new properties of this approach, such as cancellation of optical light-shift effects, are demonstrated on weak two-photon transitions in atomic rubidium and caesium, thereby improving the frequency accuracy by up to thirty times.

Morgenweg, Jonas; Barmes, Itan; Eikema, Kjeld S. E.

2014-01-01

83

Optical combing to align photoreceptors in detached retinas  

NASA Astrophysics Data System (ADS)

In this paper, we presented a novel micro-manipulating method, called 'optical combing', that could improve the retina reattachment surgery results. Optical combing adopts the working principle of optical tweezers (i.e., focused Gaussian beam produces a trapping force when it incidents onto a micro-object. The trapping force can pull the micro-object to the central point of focused laser beam. Optical combing is implemented by scanning a focused laser beam on the misaligned micro objects (such as misaligned photoreceptors). In our preliminary experiment, a set of misaligned micro glass rods was re-aligned by applying this optical combing technology, which verified our theory. In the future, this technique will be used to re-align misaligned photoreceptors in real retina.

Yin, Shizhuo; Gardner, Thomas W.; Wu, Fei; Cholker, Milind S.

2004-07-01

84

Femtosecond laser frequency comb for precision astrophysical spectroscopy  

E-print Network

High-resolution spectroscopy is a crucial tool for cosmology and the search for extrasolar planets. We present a laser comb with up to 40-GHz line spacing for use as a new spectrographic calibration source.

Kartner, Franz X.

85

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

86

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

87

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

88

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

89

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...

90

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]. Here, we present a technique for generating a visible light frequency comb from a mode-locked erbium

91

Electrostatic Comb Drive for Resonant Sensor and Actuator Applications William Chi-Keung Tang  

E-print Network

Electrostatic Comb Drive for Resonant Sensor and Actuator Applications By William Chi-Keung Tang B Chi-Keung Tang #12;ELECTROSTATIC COMB DRIVE FOR RESONANT SENSOR AND ACTUATOR APPLICATIONS by William Chi-Keung Tang ABSTRACT Interdigitated finger (comb) structures are demonstrated to be effective

Tang, William C

92

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

93

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.

94

Mechanical Control of a Microrod-Resonator Optical Frequency Comb  

NASA Astrophysics Data System (ADS)

We report on the stabilization of a microresonator-based optical frequency comb (microcomb) by way of mechanical actuation. These experiments use novel CO2-laser-machined microrod resonators, which are introduced here and feature optical Q?5×108, less than 1 minute processing time, and tunable geometry. Residual fluctuations of our 32.6 GHz microcomb line spacing reach a stability level of 5×10-15 for 1 s averaging, thereby highlighting the potential of microcombs to support modern optical-frequency standards. Furthermore, measurements of the line spacing with respect to an independent frequency reference reveal stabilization of different spectral slices of the comb with a <0.5-mHz variation among 140 comb lines spanning 4.5 THz. Together, these results demonstrate an important step in the development of microcombs, namely, that they can be fabricated and precisely controlled with simple and accessible techniques.

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

2013-07-01

95

Honeybee combs: construction through a liquid equilibrium process?  

NASA Astrophysics Data System (ADS)

Geometrical investigations of honeycombs and speculations on how honeybees measure and construct the hexagons and rhombi of their cells are centuries old. Here we show that honeybees neither have to measure nor construct the highly regular structures of a honeycomb, and that the observed pattern of combs can be parsimoniously explained by wax flowing in liquid equilibrium. The structure of the combs of honeybees results from wax as a thermoplastic building medium, which softens and hardens as a result of increasing and decreasing temperatures. It flows among an array of transient, close-packed cylinders which are actually the self-heated honeybees themselves. The three apparent rhomboids forming the base of each cell do not exist but arise as optical artefacts from looking through semi-transparent combs.

Pirk, C. W. W.; Hepburn, H. R.; Radloff, S. E.; Tautz, J.

96

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

97

Green astro-comb for HARPS-N  

NASA Astrophysics Data System (ADS)

We report the design, installation and testing of a broadband green astro-comb on the HARPS-N spectrograph at the TNG telescope. The astro-comb consists of over 7000 narrow lines (<10-6 nm width) spaced by 16 GHz (0.02 nm at 550 nm) with wavelengths stabilized to the Global Positioning System (GPS) and with flat power from 500 to 620 nm. The narrow lines are used to calibrate the spectrograph and measure its line profile. The short term sensitivity of HARPS-N is measured to be less than 2 cm/s and the long-term drift of the spectrograph is approximately 10 cm/s/day. The astrocomb has been partially automated with future work planned to turn the astro-comb into a fully automated, push button instrument.

Langellier, Nicholas; Li, Chih-Hao; Glenday, Alexander G.; Chang, Guoqing; Chen, Hung-Wen; Lim, Jinkang; Furesz, Gabor; Kärtner, Franz; Phillips, David F.; Sasselov, Dimitar; Szentgyorgyi, Andrew; Walsworth, Ronald

2014-08-01

98

Note: an asymmetric flexure mechanism for comb-drive actuators.  

PubMed

This Note presents a new asymmetric flexure design, the double parallelogram-tilted-beam double parallelogram (DP-TDP) flexure, that enables two times higher stroke in electrostatic comb-drive actuators, compared to the traditional symmetrically paired double parallelogram (DP-DP) flexure, while maintaining the same device footprint. Because of its unique kinematic configuration, the DP-TDP flexure provides an improved stiffness ratio between the bearing and actuation directions, thus delaying the on-set of sideways instability. Experimental testing of micro-fabricated comb-drive actuators with flexure beam length 1 mm and comb gap 5 ?m demonstrates a stroke of 149 ?m (at 86 V) for the proposed DP-TDP flexure, in comparison to 75 ?m (at 45 V) for the traditional DP-DP flexure. PMID:23206112

Olfatnia, M; Sood, S; Awtar, S

2012-11-01

99

Frequency stability of a femtosecond optical parametric oscillator frequency comb.  

PubMed

Carrier-envelope-offset (CEO) and pulse-repetition frequencies of a Ti:sapphire-pumped femtosecond optical parametric oscillator were locked to uncertainties of 0.09 Hz and 0.16 mHz respectively, with the CEO beat signal linewidth being stabilized to 15 Hz (instrument limited). In-loop phase-noise power spectral density measurements showed a contribution of our servo electronics to the comb-line frequency uncertainty of up to 110 Hz. Complementary time-series data implied an in-loop comb instability of 2 x 10(-11) (1-s gate time), matching the Rb-stabilized reference used and verifying that dual servo-control of the CEO and repetition frequencies was effective in stabilizing the comb to at least this precision. PMID:22109442

Ferreiro, Teresa I; Sun, Jinghua; Reid, Derryck T

2011-11-21

100

Vacuum operation of comb-drive micro display mirrors  

NASA Astrophysics Data System (ADS)

In this study, we investigate operation characteristics of a comb-drive torsion micro-mirror in vacuum. Three types of the micro-mirror of diameter 420 µm have been designed and fabricated for resonant operation at a high frequency suitable for laser scanning display. The first type (type I) is a conventional comb-drive micro-mirror with the comb fingers installed on both sides of torsion bars. The second type (type II) is a micro-mirror with slanted comb-drive structure. The third type (type III) is the same as type I except for additional comb fingers installed on a mirror plate. In the fabrication process, three masks are used in double-side lithography of a silicon-on-insulator (SOI) wafer. The fabricated micro-mirrors have the torsion resonant frequencies of 18.4 kHz, 24.5 kHz and 14.5 kHz, respectively. The optical scan angle of 5.14° is achieved for type II at a 24.5 kHz resonant frequency and 160 V actuation voltage in atmospheric air. On the other hand, due to the operation in vacuum, the rotation angle of type II increases 52 times more than that in atmospheric air, which corresponds to the decrease of operation voltage by a factor greater than 7 at the 24.5 kHz resonant frequency. The quality factor of 9735 is obtained at a pressure below 7 Pa for type II. The effects of the modified combs of the three types of mirror have been experimentally investigated by changing the environmental pressure.

Hoang Manh, Chu; Hane, Kazuhiro

2009-10-01

101

Honeybee combs: how the circular cells transform into rounded hexagons  

PubMed Central

We report that the cells in a natural honeybee comb have a circular shape at ‘birth’ but quickly transform into the familiar rounded hexagonal shape, while the comb is being built. The mechanism for this transformation is the flow of molten visco-elastic wax near the triple junction between the neighbouring circular cells. The flow may be unconstrained or constrained by the unmolten wax away from the junction. The heat for melting the wax is provided by the ‘hot’ worker bees. PMID:23864500

Karihaloo, B. L.; Zhang, K.; Wang, J.

2013-01-01

102

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

103

A "comb" structure measurement of a micrometer displacement in laser plasma propulsion  

NASA Astrophysics Data System (ADS)

A "comb" structure of beam intensity distribution is achieved to measure target displacements at the micrometer level in laser plasma propulsion experiments. Compared with single-beam and double-beam detection, the "comb" structure is more suitable for a thin film targets with a velocity lower than 10-2 m/s. Combined with a light-electric monitor, the "comb" structure can be used to measure a velocity range from 10-3 to 1 m/s. Using this "comb" structure, the coupling coefficient of aluminum ablated by nanosecond pulse laser in air is determined and compared. The results indicate that this "comb" structure is an effective experimental approach.

Zheng, Z. Y.; Gao, L.; Gao, H.; Xing, J.; Wu, X. W.

2014-08-01

104

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

105

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

106

Spectral and temporal characterization of a fused-quartz-microresonator optical frequency comb  

SciTech Connect

We report on the fabrication of high-Q, fused-quartz microresonators and the parametric generation of a frequency comb with 36-GHz line spacing using them. We have characterized the intrinsic stability of the comb in both the time and frequency domains to assess its suitability for future precision metrology applications. Intensity autocorrelation measurements and line-by-line comb control reveal near-transform-limited picosecond pulse trains that are associated with good relative phase and amplitude stability of the comb lines. The comb's 36-GHz line spacing can be readily photodetected, which enables measurements of its intrinsic and absolute phase fluctuations.

Papp, Scott B.; Diddams, Scott A. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

2011-11-15

107

Sex during Pregnancy  

MedlinePLUS

... satisfying and safe sexual relationship during pregnancy. Is Sex During Pregnancy Safe? Sex is considered safe during ... frequently asked questions about sex during pregnancy. Can sex harm my baby? No. Your baby is fully ...

108

Ramsey-comb spectroscopy: Theory and signal analysis  

NASA Astrophysics Data System (ADS)

We recently demonstrated that the spectroscopic accuracy and resolution of optical frequency combs can be obtained from a series of Ramsey-like measurements using only two amplified frequency comb pulses at variable delays. In this work we present a comprehensive analytical framework of this Ramsey-comb method in both time and frequency domains. It is shown that as opposed to traditional forms of spectroscopy, the signal analysis can be performed purely in the time domain, based on the temporal phases of the individual Ramsey signals. We give a detailed description of the robust fitting algorithm relying solely on this phase information and discuss special features such as an insensitivity to (transition-independent) spectral line-broadening mechanisms and constant phase shifts, e.g., due to the ac Stark effect from the excitation pulses themselves. The precision and resolution of the Ramsey-comb fitting method is assessed via numerical simulations, including cases of transition-dependent broadening mechanisms and phase shifts.

Morgenweg, Jonas; Eikema, Kjeld S. E.

2014-05-01

109

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

110

High resolution spectroscopy using fiber laser frequency combs  

Microsoft Academic Search

The output of a femtosecond fiber laser can be both spectrally broadened and stabilized, thereby providing a broadband coherent source in the near infrared. In the frequency domain, the result is a frequency comb with frequency stabilities at the millihertz level (relative to the reference), while in the time domain, the result is an optical pulse train with sub-femtosecond relative

I. Coddington; N. R. Newbury

2008-01-01

111

Paleontology: a cock's comb on a duck-billed dinosaur.  

PubMed

A soft tissue structure has been discovered on the head of the duck-billed dinosaur Edmontosaurus. Its similarity to a cock's comb and other sexually dimorphic structures of birds suggests that potential sexual signals existed in these extinct animals. PMID:24456984

Horner, John R

2014-01-20

112

Microchannel Integrated Comb-Type Electrode System for Electrochemical Detection  

Microsoft Academic Search

This paper describes a microchannel integrated comb-type electrode with teeth to induce serpentine flow. The configuration has led to obviate the step of assembling a microchannel because the gap between the positive and negative working electrodes actually forms a channel. Moreover, interdigitated tooth structure on the walls at each side of the channel causes turbulent flow effect in the sample

Yuheon Yi; Je-Kyun Park

2006-01-01

113

Radiation effects on surface micromachined comb drives and microengines  

Microsoft Academic Search

Surface micromachined comb drive and microengine fluence thresholds and failure modes were investigated in X-ray, electron, and proton total-dose environments. Very high fluence levels were necessary to induce motion degradation or lockup for normal device biasing or operation. For the abnormal biasing of ungrounded or partially grounded dice, significantly lower fault thresholds were observed, but still in a medium or

L. P. Schanwald; J. R. Schwank; J. J. Sniegowski; D. S. Walsh; N. F. Smith; K. A. Peterson; M. R. Shaneyfelt; P. S. Winokur; J. H. Smith; B. L. Doyle

1998-01-01

114

Development of an Extreme Ultraviolet Frequency Comb for Precision Spectroscopy.  

E-print Network

200 microwatts of XUV power is generated in each harmonic. While it is difficult to build a continuous and Martin Fer- mann at IMRA America provided us with the high power frequency comb without which the #12;vi produced via high repetition rate, intracavity high harmonic generation. The experimental apparatus

Jin, Deborah

115

Sex films  

Microsoft Academic Search

human films simultaneously, one hour in small groups to dig into feelings and attitudes, and lunch with a showing of erotic art from many cultures and ages with taped erotic music. Then we deal with the varieties of sex, with male and female masturbation, male and female homosexuality, and a couple of paraphilias films--sado-masochism, beastiality, and the like--shown simultaneously. These

Robert T. Francoeur

1977-01-01

116

Genomics of sex determination.  

PubMed

Sex determination is a major switch in the evolutionary history of angiosperm, resulting 11% monoecious and dioecious species. The genomic sequences of papaya sex chromosomes unveiled the molecular basis of recombination suppression in the sex determination region, and candidate genes for sex determination. Identification and analyses of sex determination genes in cucurbits and maize demonstrated conservation of sex determination mechanism in one lineage and divergence between the two systems. Epigenetic control and hormonal influence of sex determination were elucidated in both plants and animals. Intensive investigation of potential sex determination genes in model species will improve our understanding of sex determination gene network. Such network will in turn accelerate the identification of sex determination genes in dioecious species with sex chromosomes, which are burdensome due to no recombination in sex determining regions. The sex determination genes in dioecious species are crucial for understanding the origin of dioecy and sex chromosomes, particularly in their early stage of evolution. PMID:24682067

Zhang, Jisen; Boualem, Adnane; Bendahmane, Abdelhafid; Ming, Ray

2014-04-01

117

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

118

Fractional-Time Schrödinger Equation: Fractional Dynamics on a Comb  

E-print Network

The physical relevance of the fractional time derivative in quantum mechanics is discussed. It is shown that the introduction of the fractional time Scr\\"odinger equation (FTSE) in quantum mechanics by analogy with the fractional diffusion $\\frac{\\prt}{\\prt t}\\rightarrow \\frac{\\prt^{\\alpha}}{\\prt t^{\\alpha}}$ can lead to an essential deficiency in the quantum mechanical description, and needs special care. To shed light on this situation, a quantum comb model is introduced. It is shown that for $\\alpha=1/2$, the FTSE is a particular case of the quantum comb model. This \\textit{exact} example shows that the FTSE is insufficient to describe a quantum process, and the appearance of the fractional time derivative by a simple change $\\frac{\\prt}{\\prt t}\\rightarrow \\frac{\\prt^{\\alpha}}{\\prt t^{\\alpha}}$ in the Schr\\"odinger equation leads to the loss of most of the information about quantum dynamics.

Alexander Iomin

2011-08-31

119

Interferometric homogeneity test using adaptive frequency comb illumination.  

PubMed

The homogeneity test of glass plates in a Fizeau interferometer requires the measurement of the glass sample in reflected as well as in transmitted light. For the measurement in transmitted light, the sample has to be inserted into the ray path of a Fizeau or Twyman-Green interferometer, which leads to a nested cavity setup. To separate the interference signals from the different cavities, we illuminate a Fizeau interferometer with an adaptive frequency comb. In this way, rigid glass plates can be measured, and linear variations in the homogeneity can also be detected. The adaptive frequency comb is provided by a variable Fabry-Perot filter under broadband illumination from a superluminescence diode. 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. PMID:23518735

Mantel, Klaus; Schwider, Johannes

2013-03-20

120

High density THz frequency comb produced by coherent synchrotron radiation  

E-print Network

Frequency combs (FC) have radically changed the landscape of frequency metrology and high-resolution spectroscopy investigations extending tremendously the achievable resolution while increasing signal to noise ratio. Initially developed in the visible and near-IR spectral regions, the use of FC has been expanded to mid-IR, extreme ultra-violet and X-ray. Significant effort is presently dedicated to the generation of FC at THz frequencies. One solution based on converting a stabilized optical frequency comb using a photoconductive terahertz emitter, remains hampered by the low available THz power. Another approach is based on active mode locked THz quantum-cascade-lasers providing intense FC over a relatively limited spectral extension. Alternatively, here we show that dense powerful THz FC is generated over one decade of frequency by coherent synchrotron radiation (CSR). In this mode, the entire ring behaves in a similar fashion to a THz resonator wherein electron bunches emit powerful THz pulses quasi-synch...

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

2014-01-01

121

Frequency comb generation by CW laser injection into a quantum-dot mode-locked laser.  

PubMed

We report on frequency comb generation at 1.5 ?m by injection of a CW laser in a hybridly mode-locked InAs/InP two-section quantum-dot laser (HMLQDL). The generated comb has > 60 modes spaced by ? 4.5 GHz and a -20 dBc width of > 100 GHz (23 modes) at > 30 dB signal to background ratio. Comb generation was observed with the CW laser (red) detuned more than 20 nm outside the HMLQDL spectrum, spanning a large part of the gain spectrum of the quantum dot material. It is shown that the generated comb is fully coherent with the injected CW laser and RF frequency used to drive the hybrid mode-locking. This method of comb generation is of interest for the creation of small and robust frequency combs for use in optical frequency metrology, high-frequency (> 100 GHz) RF generation and telecommunication applications. PMID:23037259

Pinkert, T J; Salumbides, E J; Tahvili, M S; Ubachs, W; Bente, E A J M; Eikema, K S E

2012-09-10

122

Direct fiber comb stabilization to a gas-filled hollow-core photonic crystal fiber.  

PubMed

We have isolated a single tooth from a fiber laser-based optical frequency comb for nonlinear spectroscopy and thereby directly referenced the comb. An 89 MHz erbium fiber laser frequency comb is directly stabilized to the P(23) (1539.43 nm) overtone transition of (12)C(2)H(2) inside a hollow-core photonic crystal fiber. To do this, a single comb tooth is isolated and amplified from 20 nW to 40 mW with sufficient fidelity to perform saturated absorption spectroscopy. The fractional stability of the comb, ~7 nm away from the stabilized tooth, is shown to be 6 × 10(-12) at 100 ms gate time, which is over an order of magnitude better than that of a comb referenced to a GPS-disciplined Rb oscillator. PMID:25321837

Wu, Shun; Wang, Chenchen; Fourcade-Dutin, Coralie; Washburn, Brian R; Benabid, Fetah; Corwin, Kristan L

2014-09-22

123

Flattop microwave photonic filter based on optical frequency comb shaping  

Microsoft Academic Search

We present flat-top microwave photonic filters through amplitude and phase shaping of optical frequency combs. Flat-topped filters with greater than 27-dB stopband loss are demonstrated using 32 taps with both positive and negative tap coefficients. OCIS codes: (060.5625) Radio frequency photonics; (120.2440) Filters; (320.5540) Pulse shaping Microwave photonic filters bring advantages such as high speed, large bandwidth, low loss, tunability

M. H. Song; C. M. Long; E. Hamidi; R. Wu; V. R. Supradeepa; D. S. Seo; D. E. Leaird; A. M. Weiner

2011-01-01

124

Intraspecific comb usurpation in the social wasp Polistes fuscatus  

Microsoft Academic Search

Incidents of usurpation were observed in colonies of Polistes fuscatus nesting on farm buildings (1977–79) and in nestboxes (1980–84) in Johnson County, Iowa, USA. Most usurpations (84.8%) occurred in the latter half of the preworker phase of the colony cycle, which coincided with periods of high predation of combs by vertebrates. Usurpers were probably displaced single foundresses which did not

J. Klahn

1988-01-01

125

Frequency comb generation for wave transmission through the nonlinear dimer  

E-print Network

We study dynamical response of a nonlinear dimer to a symmetrically injected monochromatic wave. We find a domain in the space of frequency and amplitude of the injected wave where all stationary solutions are unstable. In this domain scattered waves carry multiple harmonics with equidistantly spaced frequencies (frequency comb effect). The instability is related to a symmetry protected bound state in the continuum whose response is singular as the amplitude of the injected wave tends to zero.

Pichugin, Konstantin N

2015-01-01

126

Electrostatic-comb drive of lateral polysilicon resonators  

Microsoft Academic Search

This paper mvestlgates the elcctrostatlc dnve and sense of polynhcon resonators parallel to the substrate, using an mterdlgtated capacitor (elec- trostatic comb) Three expenmental methods are used nucroscoplc observation mth contmuous or stroboscopic iummatlon, capacltlve sensing using an amphtude-modulation technique and SEM ob- servation The mtnnslc quality factor of the phosphorus-doped low-pressure chemlcal-vapor- deposited (LPCVD) polyslhcon resonators is 49 000

William C. Tang; Tu-Cuong H. Nguyen; Michael W. Judy; Roger T. Howe

1990-01-01

127

Frequency error estimation for frequency comb multiple access demodulation  

NASA Astrophysics Data System (ADS)

Frequency comb multiple access (FCMA) has been suggested as an efficient means of multiple access for satellite communication networks. The authors suggest a new algorithm for rapid FCMA frequency error estimation with excellent performance at low E(sub b)/N(sub o) and heavy interchannel interference. This frequency correction must be achieved before acquisition of timing and phase. The performance of the algorithm is also given.

Reisenfeld, S.; Kumar, A.

1994-04-01

128

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 ...

129

Wide and stable optical frequency comb in an intensity-modulated continuous wave pumped optical fiber  

NASA Astrophysics Data System (ADS)

This paper investigates how to obtain a wide and stable optical frequency comb in an intensity-modulated continuous-wave pumped optical fiber by straightforwardly characterizing the signal-to-noise ratio and analyzing the optimal fiber length. The stability of the obtained optical frequency comb is analyzed by a method which is similar to the eye pattern. The prospect for obtaining wider and more stable optical frequency combs is discussed.

Tang, P. H.; Yang, H.; Wang, B. Y.; Wang, W. B.

2014-11-01

130

Mid-infrared soliton and Raman frequency comb generation in silicon microrings.  

PubMed

We numerically study the mechanisms of frequency comb generation in the mid-infrared spectral region from cw-pumped silicon microring resonators. Coherent soliton comb generation may be obtained even for a pump with zero linear cavity detuning, through suitable control of the effective lifetime of free carriers from multiphoton absorption, which introduces a nonlinear cavity detuning via free-carrier dispersion. Conditions for optimal octave spanning Raman comb generation are also described. PMID:25490668

Hansson, Tobias; Modotto, Daniele; Wabnitz, Stefan

2014-12-01

131

Mid-infrared soliton and Raman frequency comb generation in silicon microrings  

NASA Astrophysics Data System (ADS)

We numerically study the mechanisms of frequency comb generation in the mid-infrared spectral region from cw pumped silicon microring resonators. Coherent soliton comb generation may be obtained even for a pump with zero linear cavity detuning, through suitable control of the effective lifetime of free-carriers from multiphoton absorption, which introduces a nonlinear cavity detuning via free-carrier dispersion. Conditions for optimal octave spanning Raman comb generation are also described.

Hansson, Tobias; Modotto, Daniele; Wabnitz, Stefan

2014-12-01

132

A Fourier transform spectrometer using resonant vertical comb actuators  

NASA Astrophysics Data System (ADS)

The design, fabrication and characterization of a novel out-of-plane vertical comb-drive actuator based lamellar grating interferometer (LGI) is reported. The interferometer utilizes resonant mode vertical comb actuators, where comb fingers are simultaneously used for actuation and as a movable diffraction grating, making the device very compact. The Fourier transform of the zeroth order intensity pattern as a function of the optical path difference gives the spectrum of light. The main advantages offered by the proposed device are a long travel range (i.e. good spectral resolution), a large clear aperture (i.e. high light efficiency), and a very simple, robust and compact spectrometer structure. Peak-to-peak 106 µm out-of-plane deflection is observed in ambient pressure and at 28 V, corresponding to a theoretical spectral resolution of about 0.4 nm in the visible band and 3.6 nm at 1.5 µm. A simple CMOS compatible process based on bulk micromachining of a silicon-on-insulator wafer is used for the device fabrication.

Ataman, Caglar; Urey, Hakan; Wolter, Alexander

2006-12-01

133

Coherent Raman spectro-imaging with laser frequency combs  

NASA Astrophysics Data System (ADS)

Advances in optical spectroscopy and microscopy have had a profound impact throughout the physical, chemical and biological sciences. One example is coherent Raman spectroscopy, a versatile technique interrogating vibrational transitions in molecules. It offers high spatial resolution and three-dimensional sectioning capabilities that make it a label-free tool for the non-destructive and chemically selective probing of complex systems. Indeed, single-colour Raman bands have been imaged in biological tissue at video rates by using ultra-short-pulse lasers. However, identifying multiple, and possibly unknown, molecules requires broad spectral bandwidth and high resolution. Moderate spectral spans combined with high-speed acquisition are now within reach using multichannel detection or frequency-swept laser beams. Laser frequency combs are finding increasing use for broadband molecular linear absorption spectroscopy. Here we show, by exploring their potential for nonlinear spectroscopy, that they can be harnessed for coherent anti-Stokes Raman spectroscopy and spectro-imaging. The method uses two combs and can simultaneously measure, on the microsecond timescale, all spectral elements over a wide bandwidth and with high resolution on a single photodetector. Although the overall measurement time in our proof-of-principle experiments is limited by the waiting times between successive spectral acquisitions, this limitation can be overcome with further system development. We therefore expect that our approach of using laser frequency combs will not only enable new applications for nonlinear microscopy but also benefit other nonlinear spectroscopic techniques.

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

2013-10-01

134

Quantum interference in two-photon frequency-comb spectroscopy  

NASA Astrophysics Data System (ADS)

Quantum interference arising from spontaneous emission, or cross-damping, is an important yet frequently overlooked systematic in precision spectroscopy experiments which aim to determine a transition frequency with an uncertainty smaller than the natural linewidth. Here, we calculate the effects of such interference in two-photon frequency-comb spectroscopy using a perturbative approach and by integration of the density matrix equations. We then apply these techniques to the two-photon spectroscopy of the hydrogen 1S-3S transition currently being performed in our group. Depending on the detection geometry, we find distortions of the line shapes which can lead to systematic errors of ˜1 kHz if such interference effects are ignored in the data analysis. This result is independent of whether a cw laser or frequency comb is used for the excitation. Finally, we propose a time-dependent detection scheme which, when used in conjunction with frequency-comb excitation, can mitigate the line distortions arising from such interference.

Yost, D. C.; Matveev, A.; Peters, E.; Beyer, A.; Hänsch, T. W.; Udem, Th.

2014-07-01

135

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 ...

136

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

137

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

138

Wide-range tunability, thermal locking, and mode-crossing effects in Kerr optical frequency combs  

NASA Astrophysics Data System (ADS)

We theoretically and experimentally investigate some effects related to the Kerr optical frequency comb generation, using a millimeter-size magnesium fluoride ultrahigh quality disk resonator. We show that the Kerr comb tunability can be extremely wide in the Turing pattern (or primary comb) regime, with an intermodal frequency that can be tuned from 4 to 229 multiple free spectral ranges (corresponding to a frequency spacing ranging from 24 GHz to 1.35 THz). We also discuss the role played by thermal locking while pumping the resonator, as well as the effect of modal crossing when broadband combs are generated.

Lin, Guoping; Saleh, Khaldoun; Henriet, Rémi; Diallo, Souleymane; Martinenghi, Romain; Coillet, Aurélien; Chembo, Yanne K.

2014-12-01

139

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...

140

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

141

Native chemical ligation at Asx-Cys, Glx-Cys: chemical synthesis and high-resolution X-ray structure of ShK toxin by racemic protein crystallography.  

PubMed

We have re-examined the utility of native chemical ligation at -Gln/Glu-Cys- [Glx-Cys] and -Asn/Asp-Cys- [Asx-Cys] sites. Using the improved thioaryl catalyst 4-mercaptophenylacetic acid (MPAA), native chemical ligation could be performed at -Gln-Cys- and Asn-Cys- sites without side reactions. After optimization, ligation at a -Glu-Cys- site could also be used as a ligation site, with minimal levels of byproduct formation. However, -Asp-Cys- is not appropriate for use as a site for native chemical ligation because of formation of significant amounts of ?-linked byproduct. The feasibility of native chemical ligation at -Gln-Cys- enabled a convergent total chemical synthesis of the enantiomeric forms of the ShK toxin protein molecule. The D-ShK protein molecule was ~50,000-fold less active in blocking the Kv1.3 channel than the L-ShK protein molecule. Racemic protein crystallography was used to obtain high-resolution X-ray diffraction data for ShK toxin. The structure was solved by direct methods and showed significant differences from the previously reported NMR structures in some regions of the ShK protein molecule. PMID:23919482

Dang, Bobo; Kubota, Tomoya; Mandal, Kalyaneswar; Bezanilla, Francisco; Kent, Stephen B H

2013-08-14

142

Modeling of octave-spanning Kerr frequency combs using a generalized mean-field Lugiato-Lefever model.  

PubMed

A generalized Lugiato-Lefever equation is numerically solved with a Newton-Raphson method to model Kerr frequency combs. We obtain excellent agreement with past experiments, even for an octave-spanning comb. Simulations are much faster than with any other technique despite including more modes than ever before. Our study reveals that Kerr combs are associated with temporal cavity solitons and dispersive waves, and opens up new avenues for the understanding of Kerr-comb formation. PMID:23282830

Coen, Stéphane; Randle, Hamish G; Sylvestre, Thibaut; Erkintalo, Miro

2013-01-01

143

ORIGINAL PAPER Synthesis and solution properties of novel comb-shaped  

E-print Network

ORIGINAL PAPER Synthesis and solution properties of novel comb-shaped acrylamide copolymers hydrophobic and hydrophilic groups were copolymerized with acrylamide to prepare the novel comb- shaped acrylamide copolymer (CPAM) through aqueous free radical polymeriza- tion. The solution properties of CPAM

144

Silicon Microring Resonator-Based Broadband Comb Switch for Wavelength-Parallel Message Routing  

E-print Network

data in a broadband silicon microring resonator-based comb switch, and observe no power penalty- dashed line) signals; measured ( ) and simulated (line) single-channel power penalty of the drop portSilicon Microring Resonator-Based Broadband Comb Switch for Wavelength-Parallel Message Routing

Bergman, Keren

145

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

146

A gigahertz multimode-diode-pumped Yb:KGW enables a strong frequency comb offset beat  

E-print Network

frequency comb offset beat signal without additional amplification or pulse compression. The ultrafast Yb power with a PCF coupling efficiency of 70%. The frequency comb offset was successfully detected with a carrier-envelope offset (CEO) frequency beat signal of 30-dB signal-to-noise ratio for a resolution

Keller, Ursula

147

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

148

Interview with a quality leader: Dr. John Combes on boards and governance.  

PubMed

Dr. Combes is senior vice president at the American Hospital Association (AHA) and president and COO of the Center for Healthcare Governance. The Interview with Dr. John Combes on Boards and Governance provides a perspective on key changes, issues, competencies, and metrics that hospital boards must address. The role of quality professionals to be effective with boards is also described. PMID:23980796

White, Susan V

2014-01-01

149

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

E-print Network

LARGE STROKE ELECTROSTATIC COMB-DRIVE ACTUATORS BASED ON A NOVEL FLEXURE MECHANISM Mohammad-plane electrostatic comb-drive actuators with stroke as large as 245 µm that is achieved by employing a novel Clamped offering significantly greater actuation stroke compared to existing designs. INTRODUCTION Electrostatic

Awtar, Shorya

150

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

151

All-fiber-based frequency comb with an intra-cavity waveguide electro-optic modulator  

Microsoft Academic Search

We develop an all-fiber-based frequency comb with an intra-cavity waveguide electro-optic modulator. A comb mode is successfully phase-locked to an optical reference. The servo bandwidth of repetition rate is approximately 400 kHz.

Yoshiaki Nakajima; Hajime Inaba; Kana Iwakuni; Kazumoto Hosaka; Atsushi Onae; Kaoru Minoshima; Feng-Lei Hong

2010-01-01

152

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 [2, 3]. Mode-locked fiber lasers using single-walled carbon nanotubes as a saturable absorber have-referenced frequency comb from a fiber laser passively modelocked by single walled carbon nanotubes. The carbon

Washburn, Brian

153

Polarization division multiplexed photonic radio-frequency channelizer using an optical comb  

NASA Astrophysics Data System (ADS)

A polarization division multiplexed photonic radio-frequency (RF) channelizer based on an optical comb is proposed and numerically investigated. A flat optical comb with nine lines is generated using two cascaded Mach-Zehnder modulators. The input broadband signal is simultaneously multicast by the optical comb and its frequency-shifted duplicate. These two combs are polarization multiplexed, spectrally sliced by a Fabry-Pérot etalon (FPE), polarization de multiplexed and then channelized by wavelength division multiplexers (WDMs). The key advantage of the proposed approach is that it releases the trade-off between the measurement range and accuracy of a conventional optical comb based channelizer by a factor of 2. The impact of the polarization misalignment, the capability of monitoring multi-frequency RF signals with different powers and the reconfigurability of the system are also evaluated.

Xian Wang, Li; Hua Zhu, Ning; Li, Wei; Wang, Hui; Yu Zheng, Jian; Guo Liu, Jian

2013-01-01

154

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

155

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

NASA Astrophysics Data System (ADS)

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.

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

156

Frequency-comb-referenced tunable diode laser spectroscopy and laser stabilization applied to laser cooling.  

PubMed

Laser cooling of trapped atoms and ions in optical clocks demands stable light sources with precisely known absolute frequencies. Since a frequency comb is a vital part of any optical clock, the comb lines can be used for stabilizing tunable, user-friendly diode lasers. Here, a light source for laser cooling of trapped strontium ions is described. The megahertz-level stability and absolute frequency required are realized by stabilizing a distributed-feedback semiconductor laser to a frequency comb. Simple electronics is used to lock and scan the laser across the comb lines, and comb mode number ambiguities are resolved by using a separate, saturated absorption cell that exhibits easily distinguishable hyperfine absorption lines with known frequencies. Due to the simplicity, speed, and wide tuning range it offers, the employed technique could find wider use in precision spectroscopy. PMID:25402914

Fordell, Thomas; Wallin, Anders E; Lindvall, Thomas; Vainio, Markku; Merimaa, Mikko

2014-11-01

157

Optical frequency comb profilometry using a single-pixel camera  

NASA Astrophysics Data System (ADS)

We demonstrate an optical profilometer composed of an ultra-stabilized mode-locked femtosecond laser, a single pixel camera, and an optoelectronic interferometer. The combination of an optical frequency comb generated by the femtosecond laser and the optoelectronic interference in radio frequecny range enables us to measure an object with a large depth much more than a wavelength of light with a wide dynamic range giving no 2? phase ambiguity. The wide dynamic range is achieved by high stability of the optical frequency comb and easy selection of the frequency. The single pixel camera is used for twodimensional imaging without a mechanical scanning. It is performed by spatial light modulation of an object beam, the coherent summation of the spatially-modulated object beam with a single photo detector, and an inverse matrix calculation. We selected two approaches to reduce the number of measurements. One was the compressive sensing that well reduced the number when an object is sparse. The other was the reversal signal generation method that reduced the number to one-half of the sampling points for any object. We demonstrated the surface profilometry for an object with the depth of several centimeters.

Hayasaki, Yoshio; Pham, Quang Duc

2014-05-01

158

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

159

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

160

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

161

A Fine-Tooth Comb to Measure the Accelerating Universe  

NASA Astrophysics Data System (ADS)

Astronomical instruments needed to answer crucial questions, such as the search for Earth-like planets or the way the Universe expands, have come a step closer with the first demonstration at the telescope of a new calibration system for precise spectrographs. The method uses a Nobel Prize-winning technology called a 'laser frequency comb', and is published in this week's issue of Science. Uncovering the disc ESO PR Photo 26a/08 A Laser Comb for Astronomy "It looks as if we are on the way to fulfil one of astronomers' dreams," says team member Theodor Hänsch, director at the Max Planck Institute for Quantum Optics (MPQ) in Germany. Hänsch, together with John Hall, was awarded the 2005 Nobel Prize in Physics for work including the frequency comb technique. Astronomers use instruments called spectrographs to spread the light from celestial objects into its component colours, or frequencies, in the same way water droplets create a rainbow from sunlight. They can then measure the velocities of stars, galaxies and quasars, search for planets around other stars, or study the expansion of the Universe. A spectrograph must be accurately calibrated so that the frequencies of light can be correctly measured. This is similar to how we need accurate rulers to measure lengths correctly. In the present case, a laser provides a sort of ruler, for measuring colours rather than distances, with an extremely accurate and fine grid. New, extremely precise spectrographs will be needed in experiments planned for the future European Extremely Large Telescope (E-ELT), which is being designed by ESO, the European Southern Observatory. These new spectrographs will need to be calibrated with even more accurate 'rulers'. In fact, they must be accurate to about one part in 30 billions - a feat equivalent to measuring the circumference of the Earth to about a millimetre! "We'll need something beyond what current technology can offer, and that's where the laser frequency comb comes in. It is worth recalling that the kind of precision required, 1 cm/s, corresponds, on the focal plane of a typical high-resolution spectrograph, to a shift of a few tenths of a nanometre, that is, the size of some molecules," explains PhD student and team member Constanza Araujo-Hauck from ESO. The new calibration technique comes from the combination of astronomy and quantum optics, in a collaboration between researchers at ESO and the Max Planck Institute for Quantum Optics. It uses ultra-short pulses of laser light to create a 'frequency comb' - light at many frequencies separated by a constant interval - to create just the kind of precise 'ruler' needed to calibrate a spectrograph. After successful tests in the MPQ laboratory in 2007, the team have successfully tested a prototype device using the laser comb at the VTT (Vacuum Tower Telescope) solar telescope in Tenerife, on 8 March 2008, measuring the spectrum of the Sun in infrared light. The results are already impressive, and the technique promises to achieve the accuracy needed to study these big astronomical questions. "In our tests in Tenerife, we have already achieved beyond state-of-the-art accuracy. Now we are going to make the system more versatile, and develop it even further," says team member Tilo Steinmetz, from Menlo Systems GmbH, a spin-off company from the Max Planck Institute, which was founded to commercialise the frequency comb technique. Having tested the technique on a solar telescope, a new version of the system is now being built for the HARPS planet-finder instrument on ESO's 3.6-metre telescope at La Silla in Chile, before being considered for future generations of instruments. One of the ambitious project to be realised with the E-ELT, called CODEX, aims to measure the recently discovered acceleration of the universe directly, by following the velocities of distant galaxies and quasars over a 20-year period. This would let astronomers test Einstein's general relativity and the nature of the recently discovered, and mysterious, dark energy. "We have to measu

2008-09-01

162

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 ...

163

Sex-linked recessive  

MedlinePLUS

Inheritance - sex-linked recessive; Genetics - sex-linked recessive; X-linked recessive ... X-linked recessive diseases usually occur in males. Males have only one X chromosome. A single recessive ...

164

Mid-infrared dual-comb spectroscopy with an optical parametric oscillator.  

PubMed

We present the first implementation of mid-infrared dual-comb spectroscopy with an optical parametric oscillator. Methane absorption spectroscopy was demonstrated with a resolution of 0.2 cm(-1) (5 GHz) at an acquisition time of ~10.4 ms over a spectral coverage at 2900-3050 cm(-1). The average power from each individual mid-infrared comb line was ~1 ?W, representing a power level much greater than typical difference-frequency-generation sources. Mid-infrared dual-comb spectroscopy opens up unique opportunities to perform broadband spectroscopic measurements with high resolution, high requisition rate, and high detection sensitivity. PMID:24104672

Zhang, Zhaowei; Gardiner, Tom; Reid, Derryck T

2013-08-15

165

Femtosecond frequency combs for optical clocks and timing transfer  

NASA Astrophysics Data System (ADS)

The rapid development of femtosecond optical frequency combs over the last decade has brought together ultrastable phase control of both cw and mode-locked lasers and ultrafast time-domain applications. Frequency-domain laser stabilization techniques applied to the ultrashort-pulse trains emitted by a mode-locked laser result in a level of optical phase control previously achievable only for radio frequencies and microwaves. I present our work extending such control to mode-locked lasers for both timing and frequency stabilization applications of optical frequency combs. I first present a microwave technique for synchronizing two independent modelocked lasers at a level of timing precision less than the duration of an optical cycle, below 1 fs of residual rms timing jitter. Using these synchronized pulses, simultaneous sum- and difference-frequency generation of 400-nm and tunable mid-infrared fs pulses is demonstrated, opening the door for broadband coherent control of atomic and molecular systems. For frequency metrology, I report on an offset-free clockwork for an optical clock based on the 3.39-mum transition in methane. The clockwork's simplicity leads to a robust and reliable table-sized optical frequency reference with instability approaching a few parts in 1014. Then I describe a directly-octave-spanning, self-referenced Ti:sapphire laser employed as the robustly-running phase-coherent clockwork for an 87Sr optical lattice clock. The optical comb distributes the 2-s coherence time of the 698-nm ultrastable clock laser to its modes spanning the visible and near-IR spectrum, and is therefore simultaneously used as a hub for measuring absolute frequencies or frequency ratios between the Sr clock and other remotely-located microwave and optical atomic standards. Finally, I report on the transfer of ultrastable frequency references, both microwave and optical, through 10-km-scale optical fiber links. Actively stabilizing the optical phase delay of such a fiber link, we are able to transfer a cw optical frequency standard with a transfer instability of 6x10 -18 at 1 s, more than two orders of magnitude lower than reported for any fiber link of similar length. Phase coherence between ends of the fiber link is preserved at the mHz linewidth level, and the transfer phase noise corresponds to less than 80 attoseconds of rms timing jitter integrated from 10 mHz to 30 MHz.

Foreman, Seth M.

166

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

167

Eroticizing Safe Sex  

Microsoft Academic Search

This paper considers several lesbian-produced safe sex tapes which engage pornographic vernacular with a dual purpose, offering both a very pointed counter to the dearth of erotic imagery depicting lesbian sex\\/sexuality specifically by and for women, but also functioning as pedagogical (self-help) tools for rethinking safe sex.

Christie Milliken

1999-01-01

168

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 ...

169

THz photomixing synthesizer based on a fiber frequency comb.  

PubMed

A frequency doubled erbium doped modelocked fiber frequency comb is used to implement a THz photomixing synthesizer. The useful THz linewidth is in order of 150 kHz and has been assessed along with the frequency accuracy by spectroscopic measurements demonstrating a relative accuracy of 10(-8) at frequencies around 1 THz. The THz synthesizer is used to implement a THz spectrometer to study the rotational absorption spectrum of carbonyl sulfide (OCS). Measurement of the principal transitions between 813 GHz and 1283 GHz allowed the properties of the THz spectrometer to be compared with competing techniques, and demonstrates the potential of the THz photomixing synthesizer as an alternative means to explore the THz domain. PMID:19997448

Mouret, Gaël; Hindle, Francis; Cuisset, Arnaud; Yang, Chun; Bocquet, Robin; Lours, Michel; Rovera, Daniele

2009-11-23

170

Supramolecular Polymerization from Polypeptide-Grafted Comb Polymers  

SciTech Connect

The helical and tubular structures self-assembled from proteins have inspired scientists to design synthetic building blocks that can be 'polymerized' into supramolecular polymers through coordinated noncovalent interactions. However, cooperative supramolecular polymerization from large, synthetic macromolecules remains a challenge because of the difficulty of controlling the structure and interactions of macromolecular monomers. Herein we report the synthesis of polypeptide-grafted comb polymers and the use of their tunable secondary interactions in solution to achieve controlled supramolecular polymerization. The resulting tubular supramolecular structures, with external diameters of hundreds of nanometers and lengths of tens of micrometers, are stable and resemble to some extent biological superstructures assembled from proteins. This study shows that highly specific intermolecular interactions between macromolecular monomers can enable the cooperative growth of supramolecular polymers. The general applicability of this strategy was demonstrated by carrying out supramolecular polymerization from gold nanoparticles grafted with the same polypeptides on the surface.

Wang, Jing [ORNL; Lu, Hua [ORNL; Kamat, Ranjan K [ORNL; Pingali, Sai Venkatesh [ORNL; Urban, Volker S [ORNL; Cheng, Jianjun [University of Illinois, Urbana-Champaign; Lin, Yao [ORNL

2011-01-01

171

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

172

The shapes of simple three and four junction comb polymers.  

PubMed

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. PMID:25591381

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

2015-01-14

173

Frequency-comb-induced radiative force on cold rubidium atoms  

NASA Astrophysics Data System (ADS)

We experimentally investigate the radiative force and laser-induced fluorescence (LIF) in cold rubidium atoms induced by pulse-train (frequency-comb) excitation. Three configurations are studied: (i) single-pulse-train excitation, (ii) two in-phase counterpropagating pulse trains, and (iii) two out-of-phase counterpropagating pulse trains. In all configurations, measured LIF is in agreement with calculations based on the optical Bloch equations. The observed forces in the first two configurations are in qualitative agreement with the model(s) used for calculating mechanical action of a pulse train on atoms; however, this is not the case for the third configuration. Possible resolution of the discrepancy is discussed.

Kregar, G.; Šanti?, N.; Aumiler, D.; Buljan, H.; Ban, T.

2014-05-01

174

Optical comb generator as an efficient short-pulse source.  

PubMed

We demonstrate a novel technique for converting a continuous-wave laser beam into a stable train of short pulses with a high repetition rate. The system, which is generally applicable, is based on a purely passive coupled-cavity optical frequency comb generator, which ensures a high overall efficiency. The repetition rate of the device is determined by the drive frequency of an electro-optic modulator and the pulse width by the rf power applied to the modulator. We have observed pulses down to 3.3 ps long at a 5.34-GHz repetition rate and an overall efficiency of 11%. The experimental results for pulse shape and width show excellent quantitative agreement with the results of a simple model. PMID:19865463

Macfarlane, G M; Bell, A S; Riis, E; Ferguson, A I

1996-04-01

175

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

176

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

177

Morphology and molecular bridging in comb- and star-shaped diblock copolymers  

NASA Astrophysics Data System (ADS)

Block copolymers spontaneously self-assemble into nanostructured morphologies with industrially attractive properties; however, the relationships between polymer architecture and self-assembled morphology are difficult to tailor for copolymers with increased conformational restrictions. Using Dissipative Particle Dynamics, the self-assembled morphology of comb- and star-shaped diblock copolymers was simulated as a function of the number of arms, arm length, weight fraction, and A-B incompatibility. As the number of arms on the star, or grafting points for the comb, was increased from three to four to six, the ability to self-assemble into ordered morphologies was restricted. The molecular bridging between adjacent ordered domains was observed for both comb- and star-shaped copolymers, which was found to be enhanced with increasing number of arms. This study illustrates that comb- and star-shaped copolymers are viable alternatives for applications that would benefit from highly bridged nanostructural domains.

Hart, Kyle E.; Abbott, Lauren J.; Lísal, Martin; Colina, Coray M.

2014-11-01

178

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

179

Broadband Kerr frequency combs and intracavity soliton dynamics influenced by high-order cavity dispersion.  

PubMed

We numerically investigate the influence of high-order dispersion (HOD) on temporal and spectral characteristics of microresonator-based optical frequency combs. Theoretical analysis based on the moment method associated with numerical simulations are utilized to study the comb evolution dynamics, showing that temporal shifts of steady-state intracavity solitons are induced by high-odd-order dispersion rather than high-even-order dispersion. The role of HOD on comb spectral envelopes is also elucidated through analyzing the intracavity dispersive wave generations. We further demonstrate that the spectral envelope of a broadband optical frequency comb can be engineered by using a cavity dispersion profile with multiple zero dispersion wavelengths. PMID:24978227

Wang, Shaofei; Guo, Hairun; Bai, Xuekun; Zeng, Xianglong

2014-05-15

180

Photonic chip based optical frequency comb using soliton induced Cherenkov radiation  

E-print Network

By continuous wave pumping of a dispersion engineered, planar silicon nitride microresonator, continuously circulating, sub-30fs short temporal dissipative solitons are generated, that correspond to pulses of 6 optical cycles and constitute a coherent optical frequency comb in the spectral domain. Emission of soliton induced Cherenkov radiation caused by higher order dispersion broadens the spectral bandwidth to 2/3 of an octave, sufficient for self referencing, in excellent agreement with recent theoretical predictions and the broadest coherent microresonator frequency comb generated to date. The ability to preserve coherence over a broad spectral bandwidth using soliton induced Cherenkov radiation marks a critical milestone in the development of planar optical frequency combs, enabling on one hand application in e.g. coherent communications, broadband dual comb spectroscopy and Raman spectral imaging, while on the other hand significantly relaxing dispersion requirements for broadband microresonator frequen...

Brasch, Victor; Geiselmann, Michael; Lihachev, Grigoriy; Pfeiffer, Martin H P; Gorodetsky, Michael L; Kippenberg, Tobias J

2014-01-01

181

Supercontinuum-based 10-GHz flat-topped optical frequency comb generation  

E-print Network

Supercontinuum-based 10-GHz flat-topped optical frequency comb generation Rui Wu,1,* Victor Torres generation from single laser source using supercontinuum in optical fibers," Electron. Lett. 29(10), 862

Purdue University

182

A weight (charge) conserving importance-weighted comb for Monte Carlo  

SciTech Connect

Importance-weighted combing techniques can be used to control particle populations through-out a problem with widely varying importances. However, a naive importance-weighted comb does not preserve the total particle weight. This is generally unimportant for neutron and photon transport. However, this can be very important in simulations of charged particles where the particles are generating the electric field that they are being transported through. From a Monte Carlo standpoint, preserving the expected weight by a combing technique produces an unbiased result. However, there may be a serious degradation to the physics of the problem if total charge is not exactly conserved. This paper describes a combing method that preserves the total weight and hence & total charge.

Booth, T.E.

1996-03-01

183

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

184

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

185

Laser diode comb spectrum amplification preserving low RIN for WDM applications  

NASA Astrophysics Data System (ADS)

Quantum dot-based diode comb lasers enable a single multi-channel-laser source for short-reach, high-speed WDM interconnects. In this paper, we demonstrate for the first time a 15 channel low RIN comb laser with 80 GHz channel spacing. We show that all the FP modes can be simultaneously directly modulated simply by modulating the pump current at 3.2 Gb/s, which indicates that the comb laser may be an ideal broadband light source in WDM-PON applications.We demonstrate that the whole comb laser spectrum can be amplified by a quantum dot SOA without increasing the relative intensity noise (RIN). Small signal amplification factor was measured as high as 30 dB and the saturated output power was as high as 15 dBm.

Yin, D.; Gubenko, A.; Krestnikov, I.; Livshits, D.; Mikhrin, S.; Kovsh, A.; Wojcik, G.

2009-11-01

186

Sensitive and Instantaneous Molecular Detection from Broadband Cavity-Enhanced Dual Comb Spectroscopy  

NASA Astrophysics Data System (ADS)

Recent experiments have demonstrated that the precisely spaced spectral lines of a laser frequency comb can be harnessed for new techniques of multi-heterodyne Fourier transform spectroscopy (also called dual-comb spectroscopy) of molecules. In one such experiment, an absorbing molecular gas was placed inside an optical cavity that is matched to the laser resonator so that it is resonant for each comb line. The sensitivity for weak absorption is much enhanced, as in cavity ring-down spectroscopy. The light transmitted by the cavity is superimposed on a second frequency comb with slightly different repetition frequency. A single fast photodetector then produces an output signal with a comb of radio frequencies due to interference between pairs of optical comb lines. The optical spectrum is thus effectively mapped into the radio frequency regime, where it becomes accessible to fast digital signal processing. Experimental proof-of-principle is carried out in the near-infrared 1 ?m region. An Yb-doped fiber frequency comb is coherently coupled to a passive resonator with a finesse of 1200, resulting in an effective interaction length between the light and the gas enhanced to 880m. The weak 3?1 band of ammonia is rotationally resolved for the first time to our knowledge. Recording times of 18 ?s are enough to span 220 cm-1 with a resolution of 0.15 cm-1. The signal to noise ratio of 380 leads to a minimum-detectable-absorption coefficient ?min of 3×10-8 cm-1 . B. Bernhardt, A. Ozawa, P. Jacquet, M. Jacquey, Y. Kobayashi, T. Udem, R. Holzwarth, G. Guelachvili, T.W. Hänsch, N. Picqué, Cavity-enhanced dual-comb spectroscopy, Nature Photonics 4, 55-57 (2010),

Bernhardt, B.; Ozawa, A.; Jacquey, M.; Jacquet, P.; Guelachvili, G.; Udem, T.; Holzwarth, R.; Kobayashi, Y.; Hänsch, T. W.; Picqué, N.

2010-06-01

187

Photonic Polarity-Switchable Ultra-Wideband Pulse Generation Using a Tunable Sagnac Interferometer Comb Filter  

Microsoft Academic Search

A photonic approach to polarity-switchable ultra-wideband (UWB) pulse generation is proposed. The proposed setup principally consists of an electrooptic phase modulator (EOPM) and a tunable optical comb filter constructed with another EOPM inside a Sagnac interferometer. The comb filter working at its linear region performs the phase-to-intensity conversion to generate UWB pulses with monocycle shape. By adjusting the bias voltage

Jianqiang Li; Kun Xu; Songnian Fu; Ming Tang; P. Shum; Jian Wu; Jintong Lin

2008-01-01

188

Characterizing fruit fly flight behavior using a microforce sensor with a new comb-drive configuration  

Microsoft Academic Search

This paper reports a MEMS microforce sensor with a novel configuration of bulk micromachined differential triplate comb drives that overcomes the difficulty of electrically isolating the two stationary capacitor comb sets in bulk micromachining. A high-yield fabrication process using deep-reactive ion etching (DRIE) on silicon-on-insulator (SOI) wafers and only three lithographic masks was utilized to construct the high aspect ratio

Yu Sun; Steven N. Fry; D. P. Potasek; Dominik J. Bell; Brad J. Nelson

2005-01-01

189

A new method for determining the plasma electron density using optical frequency comb interferometer  

SciTech Connect

A new method of plasma electron density measurement using interferometric phases (fractional fringes) of an optical frequency comb interferometer is proposed. Using the characteristics of the optical frequency comb laser, high density measurement can be achieved without fringe counting errors. Simulations show that the short wavelength and wide wavelength range of the laser source and low noise in interferometric phases measurements are effective to reduce ambiguity of measured density.

Arakawa, Hiroyuki, E-mail: arakawa@fmt.teikyo-u.ac.jp; Tojo, Hiroshi; Sasao, Hajime; Kawano, Yasunori; Itami, Kiyoshi [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-shi, Ibaraki 311-0193 (Japan)] [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka-shi, Ibaraki 311-0193 (Japan)

2014-04-15

190

RF-MEMS switching devices using vertical comb-drive actuation in the CMOS process  

Microsoft Academic Search

Radio frequency micro-electro-mechanical system (RF-MEMS) switching devices using vertical comb-drive actuation toward low-voltage actuation, fast response are presented in this paper. The switching devices, which comprise comb-drive electrodes, are actuated entirely by the electrostatic forces applied not only for the down-state but also for the up-state. The cost-effective MEMS process compatible with the complementary metal oxide semiconductor (CMOS) process is

Y. Naito; K. Nakamura; K. Onishi

2010-01-01

191

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

192

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

193

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

194

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

195

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 ...

196

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

197

Sex tourism in Thailand.  

PubMed

Many foreigners visit Thailand in search of sex. While long-distance tourism was long enjoyed by members of more privileged social classes, even the lower economical classes of Japan, Malaysia, Europe, America, and Australia can now afford to travel over long distances. This relatively new breed of tourist is more likely to be of lower socioeconomic and educational status and less likely to use condoms when having sex. An estimated 30,000 sex workers are active in Bangkok, of whom 7000/10,000 are females who work specifically in the tourism sector. 1/2-1/3 of the 600 commercial sex establishments in the city are visited by foreigners. Phuket, Pattaya, Koh Samui, and Chiangmai are also well-frequented by sex tourists. Overall, a large, diverse, inexpensive, and accessible commercial sex market exists in Thailand. One may meet sex workers quasi-ubiquitously and be assured to find someone capable of meeting one's sexual needs. With these attributes, Thailand strongly attracts tourists in search of sex. A certain degree of recklessness also prevails among those on vacation. Away from the peers and social mores of their native lands, tourists may engage in sexually activities without criticism. Likewise, Thai sex workers who cater to foreigners, especially females, enjoy more freedom and control in sexual relations than their peers who work among nationals. Neither single nor married women in Thailand are allowed much sexual freedom and are traditionally expected to be obliging docile, and submissive. The greater than normal personal latitude enjoyed by both sex worker and foreigner lead to more negotiation on condom use and overall lower use. As such, Thailand's commercial sex market with foreigners' involvement therein threatens to spread HIV to many other countries throughout the world. PMID:12286018

Van Kerkwijk, C

1992-01-01

198

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

199

Quantum dot mode locked lasers for coherent frequency comb generation  

NASA Astrophysics Data System (ADS)

Monolithic semiconductor passively mode locked lasers (MLL) are very attractive components for many applications including high bit rate telecommunications, microwave photonics and instrumentation. Owing to the three dimensional confinement of the charge carriers, quantum dot based mode-locked lasers have been the subject of intense investigations because of their improved performance compared to conventional material systems. Indeed, the inhomogeneous gain broadening and the ultrafast absorption recovery dynamics are an asset for short pulse generation. Moreover, the weak coupling of amplified spontaneous emission with the guided modes plus low loss waveguide leads to low timing jitter. Our work concentrates on InAs quantum dash nanostructures grown on InP substrate, intended for applications in the 1.55 ?m telecom window. InAs/InP quantum dash based lasers, in particular, have demonstrated efficient mode locking in single section Fabry-Perot configurations. The flat optical spectrum of about 12 nm, combined with the narrow RF beat note linewidth of about 10 kHz make them a promising technology for optical frequency comb generation. Coherence between spectral modes was assessed by means of spectral phase measurements. The parabolic spectral phase profile indicates that short pulses can be obtained provided the intracavity dispersion can be compensated by inserting a single mode fiber.

Martinez, A.; Calò, C.; Rosales, R.; Watts, R. T.; Merghem, K.; Accard, A.; Lelarge, F.; Barry, L. P.; Ramdane, A.

2013-12-01

200

Modeling and characterization of comb-actuated resonant microscanners  

NASA Astrophysics Data System (ADS)

The dynamics of the out-of-plane comb-drive actuator used in a torsional resonant mode microscanner is discussed. The microscanner is fabricated using the standard SOI technology by Fraunhofer, IPMS and utilized in various display, barcode scanning, spectroscopy and other imaging applications. The device is a parametrically excited system and exhibits hysteretic frequency response, nonlinear transient response, subharmonic oscillations, multiple parametric resonances, and alternating-oscillation-frequency behavior. Analytical and numerical models are developed to predict the parametric system dynamics. The analytical model is based on the solution of the linear Mathieu equation and valid for small angular displacements. The numerical model is valid for both small and large deflection angles. The analytical and numerical models are validated with the experimental results under various ambient pressures and excitation schemes and successfully predict the dynamics of the parametric nature of the microscanner. As many as four parametric resonances are observed at 30 mTorr. The models developed in this paper can be used to optimize the structure and the actuator.

Ataman, Caglar; Urey, Hakan

2006-01-01

201

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 new names (including new combinations) of species and subspecies be deposited in two different collections in two different countries. The type strain of R. 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 (Rule 27 and 30) and consequently would not be considered to be validly published. This resulted in a nomenclatural and taxonomic anomaly with Ruminococcus obeum being phylogenetically placed within members of the genus Blautia with 16S rRNA gene similarities of between 91.8-96.6%. In order to rectify this unsatisfactory situation, through our discussions with the American Type Culture Collection, the deposit of strain R. obeum ATCC 29174 to DSM as strain number 25238 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 25238T). PMID:25481290

Lawson, Paul A; Finegold, Sydney M

2014-12-01

202

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

203

Stigmatization of Sex Offenders  

Microsoft Academic Search

The present study examines how sex offenders perceive and respond to their social status. Using data from in-depth interviews with a sample of 24 incarcerated sex offenders approaching their release dates, analysis highlights offenders' recognition of and responses to social stigmatization. Findings highlight how interactions with members of the prison community and messages received from broader society communicate stigmatization and

Richard Tewksbury

2012-01-01

204

Sex/Gender Medicine  

PubMed Central

Sex differences in morbidity and mortality associated with cardiovascular disease have been recognized by the medical com006Dunity for decades. Investigation into the underlying biological basis of these differences was largely neglected by the scientific community until a report released by the Institute of Medicine in the United States in 2001 “Exploring the Biological Contributions to Human Health: Does Sex Matter?” Recommendations from this report included the need for more accurate use of the terms “sex” and “gender”, better tools and resources to study the biological basis of sex differences, integration of findings from different levels of biological organization and continued synergy between basic and clinical researchers. Ten years after the Institute’s report, this review evaluates some of the sex differences in cardiovascular disease, reviews new approaches to study sex differences and emphasizes areas where further research is required. In the era of personalized medicine, the study of the biological basis of sex differences promises to optimize preventive, diagnostic and therapeutic strategies for cardiovascular disease in men and women, but will require diligence by the scientific and medical communities to remember that sex does matter. PMID:19729858

Arain, Faisal A.; Kuniyoshi, Fatima H.; Abdalrhim, Ahmed D.; Miller, Virginia M.

2010-01-01

205

Sex Equity Coordinator's Handbook.  

ERIC Educational Resources Information Center

This guidebook was designed to assist sex equity coordinators in the Los Angeles Community College District in promoting the recruitment, retention, and placement of students in vocational programs that are non-traditional for their sex. The guidebook's first ten chapters present: (1) outlines of relevant legislation and legal guidelines for…

Rubenstein, Dorothy; Sillman, Donna

206

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

207

Qcl Spectroscopy at 9 ?M Calibrated with a High-Power Thulium-Based Frequency Comb  

NASA Astrophysics Data System (ADS)

Optical frequency comb synthesizers (OFCS) comprised of mode-locked femtosecond lasers can be stabilized with Hertz-level accuracy and used in combination with cw lasers for high resolution spectroscopy. As currently established OFCS technologies are confined to the near-IR, mid-IR spectroscopy requires either down-conversion of near-IR combs or up-conversion of the probing laser. Due to the near-IR absorption edge of the nonlinear crystals with extended mid-IR transparency, the conversion efficiency of nonlinear processes increases with the wavelength of the interacting fields. A more straightforward and efficient link between comb and probing laser is thus expected to be obtained by increasing the wavelength of the comb synthesizer. In this work, the use of a novel, powerful Thulium-based OFCS with emission wavelengths near 2 ?m is shown to be an excellent candidate to obtain absolute frequency calibration of quantum cascade lasers (QCL) operating at wavelengths as long as 9 ?m. Specifically, by combining the frequencies of a 9 ?m QCL with the high power 2 ?m comb in a AgGaSe_2 crystal, SFG light is created near 1.6 ?m. A portion of the 2 ?m comb is non-linearly shifted to 1.6 ?m. As the carrier envelope offset frequency (fceo) is the same for the SFG radiation and the shifted comb at 1.6 ?m, heterodyning the two signals produces a beat signal independent of fceo, eliminating the need for an octave spanning comb and f-2f interferometer. We report on the development of this instrument, and the absolute line transitions of NH_3 at 9 ?m, enabled by rapid scanning of the repetition rate of the comb enabled to increase the signal-to-noise ratio. J. Jiang, C. Mohr, J. Bethge, M. Fermann, and I. Hartl, in CLEO/Europe and EQEC 2011 Conference Digest, OSA Technical Digest (CD) PDB_1, 2001 D. Gatti, A. Gambetta, A. Castrillo, G. Galzerano, P. Laporta, L. Gainfrani and M. Marangoni Op. Exp. 19, 17520 2011

Mills, Andrew A.; Jiang, Jie; Hartl, Ingmar; Fermann, Martin; Gatti, Davide; Marangoni, Marco

2012-06-01

208

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

PubMed

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

209

Ultra broadband microwave frequency combs generated by an optical pulse-injected semiconductor laser.  

PubMed

We have demonstrated and characterized the generation of ultra broadband microwave frequency combs with an optical pulse-injected semiconductor laser. Through optical pulse injection, the microwave frequency combs generated in the slave laser (SL) have bandwidths greater than 20 GHz within a +/-5 dB amplitude variation, which is almost 3-fold of the 7 GHz relaxation oscillation frequency of the laser used. The line spacing of the comb is tunable from 990 MHz to 2.6 GHz, determined by the repetition frequency of the injection optical pulses produced by the master laser (ML) with optoelectronic feedback. At an offset frequency of 200 kHz, a single sideband (SSB) phase noise of -60 dBc/kHz (-90 dBc/Hz estimated) in the 1(st) harmonic is measured while a noise suppression relative to the injected regular pulsing state of the ML of more than 25 dB in the 17(th) harmonic is achieved. A pulsewidth of 29 ps and a ms timing jitter of 18.7 ps are obtained in the time domain for the microwave frequency comb generated. Further stabilization is realized by modulating the ML at the fundamental frequency of the injected regular pulsing state. The feasibility of utilizing the generated microwave frequency comb in frequency conversion and signal broadcasting is also explored. The conversion gain of each channel increases linearly as the signal power increases with a ratio of about 0.81 dB/dBm. PMID:20372590

Juan, Yu-Shan; Lin, Fan-Yi

2009-10-12

210

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

211

Modal expansion approach to optical-frequency-comb generation with monolithic whispering-gallery-mode resonators  

SciTech Connect

We describe a general framework based on modal expansion for the study of optical-frequency combs generated with monolithic whispering-gallery-mode resonators. We obtain a set of time-domain rate equations describing the dynamics of each mode as a function of the main characteristics of the cavity, namely, Kerr nonlinearity, absorption, coupling losses, and cavity dispersion (geometrical and material). A stability analysis of the various side modes is performed, which finds analytically the threshold power needed for comb generation. We show that the various whispering gallery modes are excited in a nontrivial way, strongly dependent on the value of the overall cavity dispersion. We demonstrate that the combs are not simply generated through a direct transfer of energy from the pumped mode to all their neighbors but rather through complex intermediate interactions. Anomalous cavity dispersion is also demonstrated to be critical for these cascading processes, and comb generation is thereby unambiguously linked to modulational instability. This theory accurately describes the emergence of spectral modulation and free spectral-range tunability in the comb. It also enables a clear understanding of the various phenomena responsible for the spectral span limitation. Our theoretical predictions are in excellent agreement with the numerical simulations, and they successfully explain the internal mechanisms responsible for the generation of hundreds of Kerr modes in monolithic whispering-gallery-mode resonators.

Chembo, Yanne K.; Yu, Nan [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

2010-09-15

212

Sex education drive opposed.  

PubMed

The Catholic Bishop's Conference of the Philippines (CBCP) recently expressed its opposition to sex education modules being taught in elementary and secondary schools under the government's population education program. In a press statement, CBCP president, Archbishop Oscar Cruz stressed that parents are responsible for teaching their children about sex and that they should closely monitor initiatives to provide their children with sex education outside of the home. The CBCP supports parents' right to reject and withdraw their children from any form of sex education which is not subsidiary and subordinate to their parents' guidance and control. That position is consistent with the doctrine affirmed in Pope John Paul II's Encyclical Familiaris Consortio. Meanwhile, in Davao City, nongovernmental organizations have appealed to educators to provide sex education correctly and accurately, without fear and religious admonition. World Health Organization research has found that teaching youth about sex correctly and accurately delays the initiation of their sexual activity. Otherwise, media influences and the earlier onset of puberty are making adolescents sexually active at earlier ages. Many teachers are afraid to discuss sex, partly due to prevailing religious conservatism. PMID:12294580

1998-11-01

213

A NEW SPECIES OF NEOCYPHOLAELAPS(ACARI : AMEROSEIIDAE) FROM BROOD COMBS OF THE INDIAN HONEY BEE (1)  

E-print Network

A NEW SPECIES OF NEOCYPHOLAELAPS(ACARI : AMEROSEIIDAE) FROM BROOD COMBS OF THE INDIAN HONEY BEE (1 by the tracheal mite, Acarapis woodi (Rennie). The brood combs were found infested also by a new species of the Indian honey bee, Apis cerana indica Fabr., from Pakistan. A list of known species of Neocypholaelaps

Paris-Sud XI, Université de

214

Optimizing the sweep cycle of time-varying comb filters for binaural dichotic presentation in sensorineural hearing impairment  

Microsoft Academic Search

Splitting of speech into two using time-varying comb filters has helped in reducing the effect of increased temporal and spectral masking simultaneously. The time varying comb filters contained pre-calculated sets of coefficients, which were selected in steps, such that a cyclic sweeping of magnitude responses occur. Presently the investigation has been carried out to find the best sweep cycle. The

Alice N. Cheeran; Prem C. Pandey

2002-01-01

215

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

216

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

217

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

218

Frequency comb assisted diode laser spectroscopy for measurement of microcavity dispersion  

NASA Astrophysics Data System (ADS)

Although invented for precision measurements of single atomic transitions, frequency combs have also become a versatile tool for broadband spectroscopy in recent years. Here, we present a novel and simple approach for broadband spectroscopy, combining the accuracy of an optical fibre-laser-based frequency comb with the ease of use of a tunable external cavity diode laser. The scheme enables broadband and fast spectroscopy of more than 4 THz bandwidth at scanning speeds up to 1 THz s-1 at sub-MHz resolution. We use this method for spectroscopy of microresonator modes and precise measurements of their dispersion, which is relevant in the context of broadband optical frequency comb generation, having recently been demonstrated in these devices. Moreover, we find excellent agreement between measured microresonator dispersion with predicted values from finite element simulations, and we show that microresonator dispersion can be tailored by adjusting their geometrical properties.

Del'Haye, P.; Arcizet, O.; Gorodetsky, M. L.; Holzwarth, R.; Kippenberg, T. J.

2009-09-01

219

Comb-calibrated frequency-modulated continuous-wave ladar for absolute distance measurements.  

PubMed

We demonstrate a comb-calibrated frequency-modulated continuous-wave laser detection and ranging (FMCW ladar) system for absolute distance measurements. The FMCW ladar uses a compact external cavity laser that is swept quasi-sinusoidally over 1 THz at a 1 kHz rate. The system simultaneously records the heterodyne FMCW ladar signal and the instantaneous laser frequency at sweep rates up to 3400 THz/s, as measured against a free-running frequency comb (femtosecond fiber laser). Demodulation of the ladar signal against the instantaneous laser frequency yields the range to the target with 1 ms update rates, bandwidth-limited 130 ?m resolution and a ~100 nm accuracy that is directly linked to the counted repetition rate of the comb. The precision is <100 nm at the 1 ms update rate and reaches ~6 nm for a 100 ms average. PMID:23938965

Baumann, Esther; Giorgetta, Fabrizio R; Coddington, Ian; Sinclair, Laura C; Knabe, Kevin; Swann, William C; Newbury, Nathan R

2013-06-15

220

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

221

Generation of a flexible optical comb in a periodically poled lithium niobate waveguide.  

PubMed

We propose and demonstrate a technique for the generation of an optical comb with tunable line spacing in a periodically poled lithium niobate (PPLN) waveguide. The technique is implemented with four input continuous waves (CWs), which generate a 19-line comb tuned to the spacing of 25 and 20 GHz. We show that each additional CW switched on out of the quasi phase-matching band at the PPLN waveguide input generates the growth of six new lines. The performance of the comb is tested modulating the lines with a 40 Gb/s differential quadrature phase shift keying data, demonstrating error-free operation. Nonuniform spacing of the input seed CWs improves the efficiency of the line generation process. PMID:24686591

Scaffardi, Mirco; Pinna, Sergio; Lazzeri, Emma; Bogoni, Antonella

2014-04-01

222

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

223

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

NASA Astrophysics Data System (ADS)

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

2011-09-01

224

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

225

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

226

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

PubMed

Phylogenetic analyses of the genus Glaciecola were performed using the sequences of the 16S rRNA gene and the GyrB protein to establish its taxonomic status. The results indicated a consistent clustering of the genus Glaciecola into two clades, with significant bootstrap values, with all the phylogenetic methods employed. Clade 1 was represented by seven species, Glaciecola agarilytica, G. aquimarina, G. arctica, G. chathamensis, G. mesophila, G. polaris and G. psychrophila, while clade 2 consisted of only three species, Glaciecola nitratireducens, G. pallidula and G. punicea. Evolutionary distances between species of clades 1 and 2, based on 16S rRNA gene and GyrB protein sequences, ranged from 93.0 to 95.0?% and 69.0 to 73.0?%, respectively. In addition, clades 1 and 2 possessed 18 unique signature nucleotides, at positions 132, 184?:?193, 185?:?192, 230, 616?:?624, 631, 632, 633, 738, 829, 1257, 1265, 1281, 1356 and 1366, in the 16S rRNA gene sequence and can be differentiated by the occurrence of a 15 nt signature motif 5'-CAAATCAGAATGTTG at positions 1354-1368 in members of clade 2. Robust clustering of the genus Glaciecola into two clades based on analysis of 16S rRNA gene and GyrB protein sequences, 16S rRNA gene sequence similarity of ?95.0?% and the occurrence of signature nucleotides and signature motifs in the 16S rRNA gene suggested that the genus should be split into two genera. The genus Paraglaciecola gen. nov. is therefore created to accommodate the seven species of clade 1, while the name Glaciecola sensu stricto is retained to represent species of clade 2. The species of clade 1 are transferred to the genus Paraglaciecola as Paraglaciecola mesophila comb. nov. (type strain DSM 15026(T)?=?KMM 241(T)), P. agarilytica comb. nov. (type strain NO2(T)?=?KCTC 12755(T)?=?LMG 23762(T)), P. aquimarina comb. nov. (type strain GGW-M5(T)?=?KCTC 32108(T)?=?CCUG 62918(T)), P. arctica comb. nov. (type strain BSs20135(T)?=?CCTCC AB 209161(T)?=?KACC 14537(T)), P. chathamensis comb. nov. (type strain E3(T)?=?CGMCC 1.7001(T)?=?JCM 15139(T)), P. polaris comb. nov. (type strain ARK 150(T)?=?CIP 108324(T)?=?LMG 21857(T)) and P. psychrophila comb. nov. (type strain 170(T)?=?CGMCC1.6130(T)?=?JCM 13954(T)). The type species of the genus Paraglaciecola is Paraglaciecola mesophila. An emended description of the genus Glaciecola is provided. In addition, a novel strain, 162Z-12(T), was isolated from seawater collected as part of an iron fertilization experiment (LOHAFEX) conducted in the Southern Ocean in 2009 and was subjected to polyphasic taxonomic characterization. Cells of 162Z-12(T) were Gram-negative, aerobic, motile, ovoid to short rod-shaped, obligatorily halophilic and possessed all the characteristics of the genus Paraglaciecola. Strain 162Z-12(T) shared the highest 16S rRNA gene sequence similarity with the type strains of P. agarilytica (99.7?%), P. chathamensis (99.7?%), P. mesophila (98.5?%) and P. polaris (98.3?%). However, it exhibited DNA-DNA relatedness of less than 70.0?% with its nearest phylogenetic relatives, well below the threshold value for species delineation. Further, strain 162Z-12(T) differed from the nearest species in several phenotypic characteristics, in addition to the occurrence of unique nucleotides G, T, T and T at positions 1194, 1269, 1270 and 1271 of the 16S rRNA gene. Based on the cumulative differences it exhibited from its nearest phylogenetic neighbours, strain 162Z-12(T) was identified as a novel member of the genus Paraglaciecola and assigned to the novel species Paraglaciecola oceanifecundans sp. nov. The type strain of Paraglaciecola oceanifecundans is 162Z-12(T) (?=?KCTC 32337(T)?=?LMG 27453(T)). PMID:24981324

Shivaji, Sisinthy; Reddy, Gundlapally Sathyanarayana

2014-09-01

227

Pricing ASX Installment Warrants Under Garch  

Microsoft Academic Search

Abstract Installment options are a generalization of compound options, where the holder pe- riodically decides whether to keep an option alive or not by paying the installment. We propose a numerical procedure, based on dynamic programming coupled with piece- wise polynomial approximations, to price installment options when the underlying asset price follows a GARCH process. Numerical experiments are carried out

Hatem Ben-Ameur; Michele Breton; Pascal Francois

2005-01-01

228

Control of Four-Level Quantum Coherence via Discrete Spectral Shaping of an Optical Frequency Comb  

SciTech Connect

We present experiments demonstrating high-resolution and wide-bandwidth coherent control of a four-level atomic system in a diamond configuration. A femtosecond frequency comb is used to excite a specific pair of two-photon transitions in cold {sup 87}Rb. The optical-phase-sensitive response of the closed-loop diamond system is studied by controlling the phase of the comb modes with a pulse shaper. Finally, the pulse shape is optimized resulting in a 256% increase in the two-photon transition rate by forcing constructive interference between the mode pairs detuned from an intermediate resonance.

Stowe, Matthew C.; Peer, Avi; Ye Jun [JILA, National Institute of Standards and Technology and University of Colorado (United States); Department of Physics, University of Colorado, Boulder, Colorado 80309-0440 (United States)

2008-05-23

229

Control of four-level quantum coherence via discrete spectral shaping of an optical frequency comb.  

PubMed

We present experiments demonstrating high-resolution and wide-bandwidth coherent control of a four-level atomic system in a diamond configuration. A femtosecond frequency comb is used to excite a specific pair of two-photon transitions in cold 87Rb. The optical-phase-sensitive response of the closed-loop diamond system is studied by controlling the phase of the comb modes with a pulse shaper. Finally, the pulse shape is optimized resulting in a 256% increase in the two-photon transition rate by forcing constructive interference between the mode pairs detuned from an intermediate resonance. PMID:18518527

Stowe, Matthew C; Pe'er, Avi; Ye, Jun

2008-05-23

230

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

231

Brillouin-Raman comb fiber laser with cooperative Rayleigh scattering in a linear cavity.  

PubMed

We demonstrate a multiple-wavelength Brillouin comb laser with cooperative Rayleigh scattering that uses Raman amplification in dispersion-compensating fiber. The laser resonator is a linear cavity formed by reflector at each end of the dispersion-compensating fiber to improve the reflectivity of the Brillouin Stokes comb. Multiple Brillouin Stokes generation has been improved in terms of optical signal-to-noise ratio and power-level fluctuation between neighboring channels. Furthermore, the linewidth of the Brillouin Stokes is uniform within the laser output bandwidth. PMID:16599211

Zamzuri, A K; Md Ali, M I; Ahmad, A; Mohamad, R; Mahdi, M A

2006-04-01

232

Coherent combs of antimatter from nonlinear electron-positron-pair creation  

NASA Astrophysics Data System (ADS)

Electron-positron-pair creation in collisions of a modulated laser pulse with a high-energy photon (nonlinear Breit-Wheeler process) is studied by means of strong-field quantum electrodynamics. It is shown that the driving pulse modulations lead to the appearance of comb structures in the energy spectra of produced positrons (electrons). It is demonstrated that these combs result from a coherent enhancement of probability amplitudes of pair creation from different modulations of the laser pulse, thus resembling the Young-type double-slit experiment for antimatter (matter) waves.

Krajewska, K.; Kami?ski, J. Z.

2014-11-01

233

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

234

Analysis of the second harmonic generation of a femtosecond optical frequency comb  

NASA Astrophysics Data System (ADS)

The second harmonic generation (SHG) of a femtosecond optical frequency comb (FOFC) has been studied. This work focuses on the SHG frequencies that are generated by the mixing of even-numbered frequency components from the original comb with odd-numbered components. It is observed that the generation of those frequencies is the reason the original FOFC and FOFC-based SHG signal have the same repetition frequency. The theoretical derivation agrees with the result of an optical experiment. Our results may be of use with the high-harmonic-generation process and FOFC-based SHG applications, including high-resolution spectroscopy, attosecond pulse generation, and precision length measurement.

Wei, Dong; Aketagawa, Masato

2014-12-01

235

Multiheterodyne spectroscopy with optical frequency combs generated from a continuous-wave laser.  

PubMed

Dual-drive Mach-Zehnder modulators were utilized to produce power-leveled optical frequency combs (OFCs) from a continuous-wave laser. The resulting OFCs contained up to 50 unique frequency components and spanned more than 200 GHz. Simple changes to the modulation frequency allowed for agile control of the comb spacing. These OFCs were then utilized for broadband, multiheterodyne measurements of CO2 using both a multipass cell and an optical cavity. This technique allows for robust measurements of trace gas species and alleviates much of the cost and complexity associated with the use of femtosecond OFCs produced with mode-locked pulsed lasers. PMID:24784078

Long, D A; Fleisher, A J; Douglass, K O; Maxwell, S E; Bielska, K; Hodges, J T; Plusquellic, D F

2014-05-01

236

Parallel fiber amplifiers with carrier–envelope drift control for coherent combination of optical frequency combs  

NASA Astrophysics Data System (ADS)

We demonstrated an active feed-forward method for compensating the relative phase drifts of fiber optical amplifiers. The frequency drifts of relative phase noise were well controlled in a variation range from ± 15?Hz of free-running, to approximately ± 1.5?Hz between the amplifier input and output. Coherent combination of two femtosecond fiber chirped-pulse amplifiers seeded by a Ti:S comb oscillator was achieved, which would benefit frequency comb combination to achieve high accuracy and high power.

Yang, Kangwen; Li, Wenxue; Shen, Xuling; Zhao, Jian; Bai, Dongbi; Ru, Qitian; Zeng, Heping

2014-12-01

237

Coherent Frequency Combs produced by Self Frequency Modulation in Quantum Cascade Lasers  

E-print Network

One salient characteristic of Quantum Cascade Laser (QCL) is its very shor 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 in sensing and measurement.

Khurgin, Jacob; Hugi, Andreas; Faist, Jerome

2013-01-01

238

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

239

Effect of solution viscosity on generating long DNA nanostrands array via patterned molecular combing  

NASA Astrophysics Data System (ADS)

In this study, we have investigated the effect of solution viscosity on generating the aligned and long DNA nanostrands array via modified molecular combing/soft lithography technique (or patterned molecular combing). By using the solution with higher viscosity, a low peeling-off speed can be applied to generate the long DNA nanostrands and the thornlike structures can be eliminated effectively. The DNA nanostrands array can also be generated by utilizing the polydimethylsiloxane stamp having microwells with larger diameter; however, variation of the lengths of the DNA nanostrands becomes greater as the solution viscosity and the size of microwells increase.

Cheng, Jun-Jie; Chang, Yuan-Hsin; Huang, Wan-Yu; Juang, Yi-Je

2009-06-01

240

Terahertz optical frequency comb generation and phase locking of an optical parametric oscillator at 665 GHz.  

PubMed

We have achieved efficient electro-optic phase modulation at high frequencies in a resonant modulator cavity. We enhance modulation by matching the phase velocities of the optical and microwave fields in the modulator substrate and by placing the modulator inside an optical cavity that is resonant for the input optical beam and the generated sidebands. An optical frequency comb with a span of 3 THz and at a spacing of 17 GHz is generated with 1 W of microwave power. The terahertz comb is utilized to phase lock an optical parametric oscillator at a signal-idler difference frequency of 665 GHz. PMID:19829605

Brothers, L R; Lee, D; Wong, N C

1994-02-15

241

SANS study on rapid shrinking of comb-type poly(N-isopropylacrylamide) gels  

NASA Astrophysics Data System (ADS)

The shrinking mechanism of comb-type poly(N-isopropylacrylamide) (NIPA) gel was investigated by small-angle neutron scattering (SANS). The SANS reveals that the microdomain structure with characteristic spacing of 460Å is developed in the comb-type NIPA gel during the shrinking process. This suggests that the freely mobiles grafted chains show the rapid dehydration to make tightly packed globules with temperature, followed by the subsequent hydrophobic intermolecular aggregation of the dehydrated graft chains. These aggregations of the NIPA chains contribute to an increase in void volume, which allows the gel having a pathway of water.

Annaka, M.; Sugiyama, M.; Matsuura, T.; Hino, M.; Fukunaga, T.; Hara, Y.; Okano, T.

2004-07-01

242

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

243

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

244

Sex differences in cardiomyopathies.  

PubMed

Cardiomyopathies are a heterogeneous group of heart muscle diseases with a variety of specific phenotypes. According to the contemporary European Society of Cardiology classification, they are classified into hypertrophic (HCM), dilated (DCM), arrhythmogenic right ventricular (ARVC), restrictive (RCM), and unclassified cardiomyopathies. Each class is aetiologically further categorized into inherited (familial) and non-inherited (non-familial) forms. There is substantial evidence that biological sex is a strong modulator of the clinical manifestation of these cardiomyopathies, and sex-specific characteristics are detectable in all classes. For the clinician, it is important to know the sex-specific aspects of clinical disease expression and the potential modes of inheritance or the hereditary influences underlying the development of cardiomyopathies, since these may aid in diagnosing such diseases in both sexes. PMID:24464619

Meyer, Sven; van der Meer, Peter; van Tintelen, J Peter; van den Berg, Maarten P

2014-03-01

245

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

246

Sex Chromosomes in Land Plants  

E-print Network

EVOLUTION OF SEX CHROMOSOMES. . . . . . . . . . . . . . . . 489 SEX CHROMOSOMES IN LAND PLANTSSex Chromosomes in Land Plants Ray Ming,1 Abdelhafid Bendahmane,2,3 and Susanne S. Renner4 1 reserved 1543-5008/11/0602-0485$20.00 Keywords land plants, pseudoautosomal region, sex determination, sex

Renner, Susanne

247

Silicon-based monolithic optical frequency comb Mark A. Foster,1  

E-print Network

that the comb line frequencies are equidistant over a bandwidth of 115 nm (14.5 THz), which is nearly an order. H. Agha, Y. Okawachi, and A. L. Gaeta, "Theoretical and experimental investigation of broadband. C. Turner, M. A. Foster, A. L. Gaeta, and M. Lipson, "Ultra-low power parametric frequency conver

Lipson, Michal

248

Conjugate FabryPerot cavity pair for improved astro-comb accuracy  

E-print Network

Society of America OCIS codes: 120.2230, 120.5060. Astro-combs are broadband (100 nm), wide-line- spacing-filtering Fabry­Perot cavity (FPC), which effectively increases the line spacing to >10 GHz, and power. This wide line spa- cing is required for high-resolution astrophysical spectro- graphs with resolving power

Walsworth, Ronald L.

249

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

250

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

251

Rapidly scanning, high resolution Yb fiber based frequency comb-Fourier transform spectrometer  

Microsoft Academic Search

Frequency comb technology has revolutionized many aspects of spectroscopic measurements, most recently exemplified by the introduction of multi-heterodyne spectroscopy, which is now replacing traditional mechanically scanning Fourier transform spectrographs, providing orders of magnitude improvements in scan rate and resolution. However, a power scalable and compact, optically integratable platform for multi- heterodyne spectroscopy is still missing. This paper demonstrates a Fourier

A. Ruehl; I. Hartl; M. E. Fermann

2009-01-01

252

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

253

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

E-print Network

:forsterite by groups at NIST have successfully demonstrated a self-referenced frequency comb, actively stabilized:forsterite crystal has the same bulk properties as that measured in Ref. [4] (doping of 0.2% by weight, absorption niobate (PPLN) crystal and beat against the high-frequency end of the octave to reveal the f0 beat signal

Washburn, Brian

254

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

255

Coherence Holography and Spatial Frequency Comb for 3-D Coherence Imaging  

E-print Network

Coherence Holography and Spatial Frequency Comb for 3-D Coherence Imaging Mitsuo Takeda, Wei Wang holography technique, called coherence holography, and a related technique for dispersion-free 3-D coherence: (090.0090) Holography; (030.1640) Coherence; (100.3010) Image reconstruction techniques; (110

Rosen, Joseph

256

Gigahertz self-referenceable frequency comb from a semiconductor disk laser  

E-print Network

comb from a vertical external-cavity surface-emitting laser (VECSEL) passively modelocked with a semiconductor saturable absorber mirror (SESAM). The VECSEL delivers 231-fs pulses with an average power of 100. Härkönen, T. Leinonen, L. Orsila, J. Lyytikäinen, G. Steinmeyer, and M. Guina, "Mode-locked VECSEL emitting

Keller, Ursula

257

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

258

F. Combes and D. Barret (eds) EDPS Conference Series in Astronomy &Astrophysics  

E-print Network

SF2A 2002 F. Combes and D. Barret (eds) EDPS Conference Series in Astronomy &Astrophysics NEW APPROACHES FOR THE SEARCH FOR BINARY PLANETS AND MOONS OF EXTRASOLAR PLANETS Schneider, J. 1 , Arnold, L. 2 and Borkowski, V. 3 The search for binary planets and for satellites of extrasolar planets is rele- vant

Arnold, Luc

259

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

260

DNA combing on low-pressure oxygen plasma modified polysilsesquioxane substrates for single-molecule studies  

E-print Network

assay using pinched flow coupled droplet microfluidics Biomicrofluidics 8, 034104 (2014); 10; accepted 28 July 2014; published online 6 August 2014) Molecular combing and flow-induced stretching demonstrate the use of our platform to observe DNA-RNA polymerase com- plexes and cancer drug cisplatin

261

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

262

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

263

Roman mining on Exmoor: a geomorphological approach at Anstey's Combe, Dulverton  

Microsoft Academic Search

A survey of valley fills in south-facing combes (headwater valleys) along the south side of the Exmoor massif revealed an anomalously deep infill in one valley. This infill of up to 5 m depth had been gullied revealing a complex stratigraphy. Studies of the stratigraphy, clast orientation and shape suggested several accumulation episodes under different environmental conditions commencing in a

Antony Brown; Jenny Bennett; Edward Rhodes

2009-01-01

264

Machine Vision Assistance for Flex Cable-Actuator Comb Manufacturing in Hard Disk Drives  

Microsoft Academic Search

The work presented in this paper suggests an automated manufacturing method for assembling of flexible printed circuit cable assembly onto actuator comb-like structure in high capacity hard disk drives. Apart from traditional alignment methods, robotic vision guided method and assembling system are developed and discussed in this paper. Its capabilities of reaching micro-scale position and alignment accuracy are demonstrated in

J. Y. Chang; J. Y. Shen

2008-01-01

265

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

PubMed

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. PMID:23149932

Bauer, Daniel; Bienefeld, Kaspar

2013-01-01

266

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

267

Molecular combing in the analysis of developmentally regulated amplified segments of Bradysia hygida.  

PubMed

Molecular combing technology is an important new tool for the functional and physical mapping of genome segments. It is designed to identify amplifications, microdeletions, and rearrangements in a DNA sequence and to study the process of DNA replication. This technique has recently been used to identify and analyze the dynamics of replication in amplified domains. In Bradysia hygida, multiple amplification initiation sites are predicted to exist upstream of the BhC4-1 gene. However, it has been impossible to identify them using the available standard techniques. The aim of this study was to optimize molecular combing technology to obtain DNA fibers from the polytene nuclei of the salivary glands of B. hygida to study the dynamics of DNA replication in this organism. Our results suggest that combing this DNA without prior purification of the polytene nuclei is possible. The density, integrity, and linearity of the DNA fibers were analyzed, fibers 50 to 300 kb in length were detected, and a 9-kb fragment within the amplified region was visualized using biotin detected by Alexa Fluor 488-conjugated streptavidin technique. The feasibility of physically mapping these fibers demonstrated in this study suggests that molecular combing may be used to identify the replication origin of the BhC4-1 amplicon. PMID:22911590

Passos, K J R; Togoro, S Y; Carignon, S; Koundrioukoff, S; Lachages, A-M; Debatisse, M; Fernandez, M A

2012-01-01

268

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

269

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

270

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

271

Astronomical optical frequency comb generation in nonlinear fibres and ring resonators: optimization studies  

NASA Astrophysics Data System (ADS)

We here discuss recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam. Two different platforms (and approaches) are numerically and experimentally investigated targeting medium and low resolution spectrographs at astronomical facilities in which innoFSPEC is currently involved. In the first approach, a frequency comb is generated by propagating two lasers through three nonlinear stages - the first two stages serve for the generation of low-noise ultra-short pulses, while the final stage is a low-dispersion highly-nonlinear fibre where the pulses undergo strong spectral broadening. In our approach, the wavelength of one of the lasers can be tuned allowing the comb line spacing being continuously varied during the calibration procedure - this tuning capability is expected to improve the calibration accuracy since the CCD detector response can be fully scanned. The input power, the dispersion, the nonlinear coefficient, and fibre lengths in the nonlinear stages are defined and optimized by solving the Generalized Nonlinear Schrodinger Equation. Experimentally, we generate the 250GHz line-spacing frequency comb using two narrow linewidth lasers that are adiabatically compressed in a standard fibre first and then in a double-clad Er/Yb doped fibre. The spectral broadening finally takes place in a highly nonlinear fibre resulting in an astro-comb with 250 calibration lines (covering a bandwidth of 500 nm) with good spectral equalization. In the second approach, we aim to generate optical frequency combs in dispersion-optimized silicon nitride ring resonators. A technique for lowering and flattening the chromatic dispersion in silicon nitride waveguides with silica cladding is proposed and demonstrated. By minimizing the waveguide dispersion in the resonator two goals are targeted: enhancing the phase matching for non-linear interactions and producing equally spaced resonances. For this purpose, instead of one cladding layer our design incorporates two layers with appropriate thicknesses. We demonstrate a nearly zero dispersion (with +/- 4 ps/nm-km variation) over the spectral region from 1.4 to 2.3 microns. The techniques reported here should open new avenues for the generation of compact astronomical frequency comb sources on a chip or in nonlinear fibres.

Chavez Boggio, J. M.; Fremberg, T.; Bodenmüller, D.; Wysmolek, M.; Sanyic, H.; Fernando, H.; Neumann, J.; Kracht, D.; Haynes, R.; Roth, M. M.

2012-09-01

272

XUV frequency-comb metrology on the ground state of helium  

SciTech Connect

The operation of a frequency comb at extreme ultraviolet (xuv) wavelengths based on pairwise amplification and nonlinear upconversion to the 15th harmonic of pulses from a frequency-comb laser in the near-infrared range is reported. It is experimentally demonstrated that the resulting spectrum at 51 nm is fully phase coherent and can be applied to precision metrology. The pulses are used in a scheme of direct-frequency-comb excitation of helium atoms from the ground state to the 1s4p and 1s5p {sup 1} P{sub 1} states. Laser ionization by auxiliary 1064 nm pulses is used to detect the excited-state population, resulting in a cosine-like signal as a function of the repetition rate of the frequency comb with a modulation contrast of up to 55%. Analysis of the visibility of this comb structure, thereby using the helium atom as a precision phase ruler, yields an estimated timing jitter between the two upconverted-comb laser pulses of 50 attoseconds, which is equivalent to a phase jitter of 0.38 (6) cycles in the xuv at 51 nm. This sets a quantitative figure of merit for the operation of the xuv comb and indicates that extension to even shorter wavelengths should be feasible. The helium metrology investigation results in transition frequencies of 5 740 806 993 (10) and 5 814 248 672 (6) MHz for excitation of the 1s4p and 1s5p {sup 1} P{sub 1} states, respectively. This constitutes an important frequency measurement in the xuv, attaining high accuracy in this windowless part of the electromagnetic spectrum. From the measured transition frequencies an eight-fold-improved {sup 4}He ionization energy of 5 945 204 212 (6) MHz is derived. Also, a new value for the {sup 4}He ground-state Lamb shift is found of 41 247 (6) MHz. This experimental value is in agreement with recent theoretical calculations up to order m{alpha}{sup 6} and m{sup 2}/M{alpha}{sup 5}, but with a six-times-higher precision, therewith providing a stringent test of quantum electrodynamics in bound two-electron systems.

Kandula, Dominik Z.; Gohle, Christoph; Pinkert, Tjeerd J.; Ubachs, Wim; Eikema, Kjeld S. E. [LaserLaB Amsterdam, VU University, De Boelelaan 1081, NL-1081HV Amsterdam (Netherlands)

2011-12-15

273

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

274

Synthesis and properties of star-comb polymers and their doxorubicin conjugates.  

PubMed

We describe a six-step synthesis to water-soluble doxorubicin (DOX)-loaded biodegradable PEGylated star-comb polymers with favorable pharmaceutical properties by atom transfer radical polymerization (ATRP) starting with a commercially available tripentaerythritol carrying eight reactive sites. The low polydispersity polymers degrade in a stepwise manner into lower molecular weight (MW) fragments by 15 days at 37 °C at either pH 5.0 or pH 7.4. The half-life of the star-comb polymers in blood is dependent upon the molecular weight; the 44 kDa star-comb has a t(1/2, ?) of 30.5 ± 2.1 h, which is not significantly changed (28.6 ± 2.7 h) when 6.6 wt % of DOX is attached to it via a pH-sensitive hydrazone linker. The star-comb polymers have low accumulation in organs but a high accumulation in C26 flank tumors implanted in Balb/C mice. The hydrodynamic diameter of polymer-DOX conjugates measured by dynamic light scattering increases from 8 to 35 to 41 nm as the loading is increased from 6.6 to 8.4 to 10.2 wt %. Although there is no significant difference in the t(1/2, ?) or in the accumulation of polymer-DOX in C-26 tumors, the uptake of polymer in the spleen is significantly higher for polymers with DOX loadings greater than 6.6 wt %. Polymer accumulation in other vital organs is independent of the DOX loading. The facile synthesis, biodegradability, long circulation time, and high tumor accumulation of the attached drug suggests that the water-soluble star-comb polymers have promise in therapeutic applications. PMID:21375296

Chen, Bo; van der Poll, Derek G; Jerger, Katherine; Floyd, William C; Fréchet, Jean M J; Szoka, Francis C

2011-04-20

275

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

276

Generation of a 650 nm - 2000 nm Laser Frequency Comb based on an Erbium-Doped Fiber Laser  

E-print Network

We present a laser frequency comb based upon a 250 MHz mode-locked erbium-doped fiber laser that spans more than 300 terahertz of bandwidth, from 660 nm to 2000 nm. The system generates 1.2 nJ, 70 fs pulses at 1050 nm by amplifying the 1580 nm laser light in Er:fiber, followed by nonlinear broadening to 1050 nm and amplification in Yb:fiber. Extension of the frequency comb into the visible is achieved by supercontinuum generation from the 1050 nm light. Comb coherence is verified with cascaded f-2f interferometry and comparison to a frequency stabilized laser.

Ycas, Gabriel; Diddams, Scott A

2012-01-01

277

PROPORTION DES SEXES (Sex-ratio) CHEZ LES VOLAILLES  

E-print Network

PROPORTION DES SEXES («Sex-ratio») CHEZ LES VOLAILLES I. - R�SULTAT GLOBAL ET CONSID�RATIONS plusieurs troupeaux, la proportion des sexes à 8 semaines d'âge, au total, ne s'écarte pas significativement'appliquerait pour la « sex-ratio » observée à un âge ultérieur. INTRODUCTION Les ob servations sur la proportion des

Paris-Sud XI, Université de

278

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

279

Children of Sex Rings.  

ERIC Educational Resources Information Center

Outlines three major differentiating categories of children who were sexually abused by sex rings: level of fear, ability to trust, and disclosure confusion. Addresses denial and resistance regarding child sexual exploitation by a ring among practitioners in the child welfare system. (Author/BB)

Hunt, Patricia; Baird, Margaret

1990-01-01

280

Adolescents and sex.  

PubMed

Adolescent health problems in the Philippines are identified as follows: adolescent unwanted pregnancy, early marriage, abortion and sometimes death, sexually transmitted disease (STD), AIDS, inadequate knowledge about sex and reproduction (population education), taboos, inadequate resources directed to youth, and personnel insufficiently trained for gender sensitive and adolescent sensitive counseling. A recent University of the Philippines Population Institute survey reported that only 10% of urban respondents and 8.1% of rural respondents considered virginity to be unimportant. 33% in urban and 29% in rural areas consent to premarital sex if the couple were "in love" and there was a promise of marriage. Premarital sex is increasing, but was lower among those who grew up with their parents. Population education is compulsory but teachers are ill equipped, unknowledgeable about the latest technology, and biased. Human reproduction is taught but family planning methods are frequently ignored. The topic is taboo between parents and children. Acquisition of knowledge is haphazard at best. Government resources are directed to adult reproductive women. Emphasis needs to be placed on the importance and proper use of pills, condoms, IUDs, and diaphragms. Vasectomy and tubal ligation should be readily available. Youth should be taught rhythm, basal body temperature, and Billings ovulation methods. Misconceptions should be debunked. Sex education, STD prevention, and counseling for adolescents are available in only 5 centers in the Philippines, as reported by the International Center on Adolescent Fertility; this is adequate to serve the almost 50% of the population 18 years. PMID:12285922

Castro, C; Palomar Castro, Y

1992-01-01

281

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

282

Evolution, Sex, and Jealousy  

Microsoft Academic Search

When asked to choose which would be most upsetting, a mate’s sexual or emotional infidelity, past research has demonstrated that men are more likely than women to choose sexual infidelity, whereas women are more likely than men to choose emotional infidelity. Explanation of this sex difference has been controversial. In the current study we attempted to replicate previous research by

Michael W. Wiederman; Erica Kendall

1999-01-01

283

Genes and brain sex differences.  

PubMed

Throughout development, numerous biological events occur that differentially affect males and females. Specifically, sex-determining genes that are triggered by the sex-chromosome complement initiate a series of events that determine an organism's sex and lead to the differentiation of the body in sex-specific ways. Such events contribute to many unique sex differences, including the susceptibility to different diseases. Although it was believed that sex hormones singularly differentiated the brain and body, there is emerging research showing that genes also play a direct role. In this chapter, we review this line of work and focus on the use of a unique mouse model that separates the effect of gonadal hormones and sex chromosomes. As genetic technology continues to advance, our understanding of the role that hormones and genes play in sex differences can be used to advance the physical and mental health of both men and women. PMID:21094886

Sánchez, Francisco J; Vilain, Eric

2010-01-01

284

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

285

Sex, Violence and Movie Viewing  

MedlinePLUS

... the lower right-hand corner of the player. Sex, Violence and Movie Viewing HealthDay October 20, 2014 ... Transcript Are parents becoming desensitized to violence and sex in movies targeting kids? Researchers recruited 1,000 ...

286

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- ...

287

High-power ultra-broadband frequency comb from ultraviolet to infrared by high-power fiber amplifiers.  

PubMed

A high-power ultra-broadband frequency comb covering the spectral range from ultraviolet to infrared was generated directly by nonlinear frequency conversion of a multi-stage high-power fiber comb amplifier. The 1030-nm infrared spectral fraction of a broadband Ti:sapphire femtosecond frequency comb was power-scaled up to 100 W average power by using a large-mode-area fiber chirped-pulse amplifier. We obtained a frequency-doubled green comb at 515 nm and frequency-quadrupled ultraviolet pulses at 258 nm with the average power of 12.8 and 1.62 W under the input infrared power of 42.2 W, respectively. The carrier envelope phase stabilization was accomplished with an ultra-narrow line-width of 1.86 mHz and a quite low accumulated phase jitter of 0.41 rad, corresponding to a timing jitter of 143 as. PMID:22714317

Yang, Kangwen; Li, Wenxue; Yan, Ming; Shen, Xuling; Zhao, Jian; Zeng, Heping

2012-06-01

288

High-power mid-infrared frequency comb from a continuous-wave-pumped bulk optical parametric oscillator.  

PubMed

We demonstrate that it is possible to obtain a mid-infrared optical frequency comb (OFC) experimentally by using a continuous-wave-pumped optical parametric oscillator (OPO). The comb is generated without any active modulation. It is based on cascading quadratic nonlinearities that arise from intra-cavity phase mismatched second harmonic generation of the signal wave that resonates in the OPO. The generated OFC is transferred from the signal wavelength (near-infrared) to the idler wavelength (mid-infrared) by intracavity difference frequency generation between the OPO pump wave and the signal comb. We have produced a mid-infrared frequency comb which is tunable from 3.0 to 3.4 µm with an average output power of up to 3.1 W. PMID:24921755

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

2014-05-01

289

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

290

Sex Differences and Sex Steroids in Lung Health and Disease  

PubMed Central

Sex differences in the biology of different organ systems and the influence of sex hormones in modulating health and disease are increasingly relevant in clinical and research areas. Although work has focused on sex differences and sex hormones in cardiovascular, musculoskeletal, and neuronal systems, there is now increasing clinical evidence for sex differences in incidence, morbidity, and mortality of lung diseases including allergic diseases (such as asthma), chronic obstructive pulmonary disease, pulmonary fibrosis, lung cancer, as well as pulmonary hypertension. Whether such differences are inherent and/or whether sex steroids play a role in modulating these differences is currently under investigation. The purpose of this review is to define sex differences in lung structure/function under normal and specific disease states, with exploration of whether and how sex hormone signaling mechanisms may explain these clinical observations. Focusing on adult age groups, the review addresses the following: 1) inherent sex differences in lung anatomy and physiology; 2) the importance of certain time points in life such as puberty, pregnancy, menopause, and aging; 3) expression and signaling of sex steroid receptors under normal vs. disease states; 4) potential interplay between different sex steroids; 5) the question of whether sex steroids are beneficial or detrimental to the lung; and 6) the potential use of sex steroid signaling as biomarkers and therapeutic avenues in lung diseases. The importance of focusing on sex differences and sex steroids in the lung lies in the increasing incidence of lung diseases in women and the need to address lung diseases across the life span. PMID:22240244

Townsend, Elizabeth A.; Miller, Virginia M.

2012-01-01

291

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

292

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

293

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

294

Sex Stereotyping by Tomorrow's Executives.  

ERIC Educational Resources Information Center

Describes a study in which 512 college seniors were surveyed to see if members of one sex would implicitly stereotype by sex to a greater degree than the other. Questions concerned job/home conflicts and selection and promotion. Results indicated that men and women are equally guilty of sex stereotyping, which works against women in the workplace.…

Kovach, Kenneth A.

1985-01-01

295

Juvenile Sex Offenders in Diversion  

Microsoft Academic Search

This study was designed to address the treatment of juvenile sex offenders within diversion programs. Using data from 32 diversion programs in Colorado during the 1998–1999 fiscal year, the study observed the demographic and legal characteristics of 112 juvenile (Mean age = 14.64) sex offenders referred to diversion programs for seven types of sex assault, incest, and indecent exposure charges.

Justin S. Campbell; Cherise Lerew

2002-01-01

296

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

297

"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

298

Multi-delay, phase coherent pulse pair generation for precision Ramsey-frequency comb spectroscopy.  

PubMed

We demonstrate the generation of phase-stable mJ-pulse pairs at programmable inter-pulse delays up to hundreds of nanoseconds. A detailed investigation of potential sources for phase shifts during the parametric amplification of the selected pulses from a Ti:Sapphire frequency comb is presented, both numerically and experimentally. It is shown that within the statistical error of the phase measurement of 10 mrad, there is no dependence of the differential phase shift over the investigated inter-pulse delay range of more than 300 ns. In combination with nonlinear upconversion of the amplified pulses, the presented system will potentially enable short wavelength (<100 nm), multi-transition Ramsey-frequency comb spectroscopy at the kHz-level. PMID:23482099

Morgenweg, J; Eikema, K S E

2013-03-11

299

Fractional-Time Schr\\"odinger Equation: Fractional Dynamics on a Comb  

E-print Network

The physical relevance of the fractional time derivative in quantum mechanics is discussed. It is shown that the introduction of the fractional time Scr\\"odinger equation (FTSE) in quantum mechanics by analogy with the fractional diffusion $\\frac{\\prt}{\\prt t}\\rightarrow \\frac{\\prt^{\\alpha}}{\\prt t^{\\alpha}}$ can lead to an essential deficiency in the quantum mechanical description, and needs special care. To shed light on this situation, a quantum comb model is introduced. It is shown that for $\\alpha=1/2$, the FTSE is a particular case of the quantum comb model. This \\textit{exact} example shows that the FTSE is insufficient to describe a quantum process, and the appearance of the fractional time derivative by a simple change $\\frac{\\prt}{\\prt t}\\rightarrow \\frac{\\prt^{\\alpha}}{\\prt t^{\\alpha}}$ in the Schr\\"odinger equation leads to the loss of most of the information about quantum dynamics.

Iomin, Alexander

2011-01-01

300

Frequency-comb-referenced mid-infrared source for high-precision spectroscopy.  

PubMed

We report on a tunable continuous-wave mid-infrared optical parametric oscillator (OPO), which is locked to a fully stabilized near-infrared optical frequency comb using a frequency doubling scheme. The OPO is used for 40 GHz mode-hop-free, frequency-comb-locked scans in the wavelength region between 2.7 and 3.4 ?m. We demonstrate the applicability of the method to high-precision cavity-ring-down spectroscopy of nitrous oxide (N2O) and water (H2O) at 2.85 µm and of methane (CH4) at 3.2 ?m. PMID:25607205

Peltola, Jari; Vainio, Markku; Fordell, Thomas; Hieta, Tuomas; Merimaa, Mikko; Halonen, Lauri

2014-12-29

301

Near infrared frequency comb vernier spectrometer for broadband trace gas detection.  

PubMed

We present a femtosecond frequency comb vernier spectrometer in the near infrared with a femtosecond Er doped fiber laser, a scanning high-finesse cavity and an InGaAs camera. By utilizing the properties of a frequency comb and a scanning high-finesse cavity such a spectrometer provides broad spectral bandwidth, high spectral resolution, and high detection sensitivity on a short time scale. We achieved an absorption sensitivity of ~8 × 10(-8) cm(-1)Hz(-1/2), corresponding to a detection limit of ~70 ppbv for acetylene, with a resolution of ~1.1 GHz in single images taken in 0.5 seconds and covering a frequency range of ~5 THz. Such measurements have broad applications for sensing greenhouse gases in this fingerprint near infrared region with a simple apparatus. PMID:25321773

Zhu, Feng; Bounds, James; Bicer, Aysenur; Strohaber, James; Kolomenskii, Alexandre A; Gohle, Christoph; Amani, Mahmood; Schuessler, Hans A

2014-09-22

302

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

303

Resonant light scattering of a laser frequency comb by a quantum dot  

NASA Astrophysics Data System (ADS)

We investigate the spectral and temporal properties of light scattered near resonantly by a single quantum dot when the incident laser field is a frequency comb consisting of a superposition of monochromatic waves equidistant in frequency. Such fields encompass those generated by, e.g., a periodically pulsed laser. A general theoretical treatment for the calculation of first- and second-order correlation functions is given which takes account of spectral diffusion through a slowly varying detuning from resonance, permitting accurate comparison with experiments. We explore the two distinct regimes in which the frequency-comb separation is either larger or smaller than the radiative decay rate. We verify the validity of our calculations by a comparison with experimental data for the case of a bichromatic field and discuss the manifestation of phase coherence between the incoming field and the scattered single-photon wave packet.

Konthasinghe, K.; Peiris, M.; Muller, A.

2014-08-01

304

Flexible frequency comb generation in a periodically poled lithium niobate waveguide enabling optical multicasting.  

PubMed

We propose and demonstrate a technique for the generation of a coherent optical comb, with tunable line spacing in a periodically poled lithium niobate (PPLN) waveguide. A single continuous wave laser is modulated to generate three phase-locked seed lines, which are injected into a PPLN waveguide, to obtain line multiplication. The line spacing is set acting on the frequency of the electrical signal driving the modulator. The quality of the comb is verified measuring the autocorrelation, the phase noise, and the linewidth of the generated lines. With the same scheme, we demonstrate optical multicasting. From a single quadrature phase shift keying signal, modulated at 12.5 and 25 GBaud, five replicas are generated, with spacing 25 and 37.5 GHz. The performance of each signal replica is measured after transmission through 80 km of a single-mode fiber, demonstrating operation with a bit error rate value lower than the forward error correction threshold. PMID:25361135

Vercesi, Valeria; Pinna, Sergio; Meloni, Gianluca; Scotti, Filippo; Potì, Luca; Bogoni, Antonella; Scaffardi, Mirco

2014-10-15

305

Novel active comb-shaped dry electrode for EEG measurement in hairy site.  

PubMed

Electroencephalography (EEG) is an important biopotential, and has been widely applied in clinical applications. The conventional EEG electrode with conductive gels is usually used for measuring EEG. However, the use of conductive gel also encounters with the issue of drying and hardening. Recently, many dry EEG electrodes based on different conductive materials and techniques were proposed to solve the previous issue. However, measuring EEG in the hairy site is still a difficult challenge. In this study, a novel active comb-shaped dry electrode was proposed to measure EEG in hairy site. Different form other comb-shaped or spike-shaped dry electrodes, it can provide more excellent performance of avoiding the signal attenuation, phase distortion, and the reduction of common mode rejection ratio. Even under walking motion, it can effectively acquire EEG in hairy site. Finally, the experiments for alpha rhythm and steady-state visually evoked potential were also tested to validate the proposed electrode. PMID:25137719

Huang, Yan-Jun; Wu, Chung-Yu; Wong, Alice May-Kuen; Lin, Bor-Shyh

2015-01-01

306

Thermally switchable and discretely tunable comb filter with a linearly chirped fiber Bragg grating  

NASA Astrophysics Data System (ADS)

We propose and experimentally demonstrate a novel switchable and discretely tunable comb filter based on a thermally induced linearly chirped fiber Bragg grating. Experimentally we achieved a thermally induced optical bandpass filter that has eight switchable passband peaks with peak separations of 1.6 and 3.2 nm, a very narrow bandwidth (as small as 10 pm) of each peak, a tunable range of 16.5 nm, and a greater than 25 dB rejection ratio. Two spectral peaks separated by only 0.8 nm were also obtained with this comb filter. This filter provides the unique advantages of an all-fiber structure, switchable spectral peaks, independent tuning of the center wavelength and wavelength spacing of the spectral peaks, low polarization sensitivity, simple structure, ease of fabrication, and low cost.

Ngo, N. Q.; Liu, D.; Tjin, S. C.; Dong, Xinyong; Shum, Ping

2005-11-01

307

Optical phase-noise dynamics of Titanium:sapphire optical frequency combs  

E-print Network

Stabilized optical frequency combs (OFC) can have remarkable levels of coherence across their broad spectral bandwidth. We study the scaling of the optical noise across hundreds of nanometers of optical spectra. We measure the residual phase noise between two OFC's (having offset frequencies $f^{(1)}_0 $ and $f^{(2)}_0$) referenced to a common cavity-stabilized narrow linewidth CW laser. Their relative offset frequency $ \\Delta f_0 = f^{(2)}_0 - f^{(1)}_0 $, which appears across their entire spectra, provides a convenient measure of the phase noise. By comparing $\\Delta f_0$ at different spectral regions, we demonstrate that the observed scaling of the residual phase noise is in very good agreement with the noise predicted from the standard frequency comb equation.

Quraishi, Qudsia; Hollberg, Leo

2014-01-01

308

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

309

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

310

Evaluation of the clock laser for an Yb lattice clock using an optic fiber comb.  

PubMed

A light source to drive the (1)S0-(3)P0 transition in Yb atoms is generated by 2 solid state lasers: a Nd:YAG laser and an Yb:YAG laser, using a sum-frequency generation (SFG) scheme. With a ridge waveguide (WG) periodically poled lithium niobate (PPLN) device, SFG power of about 150 mW is obtained at the required frequency. The zero-expansion temperature of a Fabry-Pérot etalon was determined by using a home-made fiber-based optical frequency comb running continuously for weeks. Frequency stabilization of the clock laser system was also evaluated by the optical frequency comb. PMID:20211777

Hosaka, Kazumoto; Inaba, Hajime; Nakajima, Yoshiaki; Yasuda, Masami; Kohno, Takuya; Onae, Atsushi; Hong, Feng-Lei

2010-03-01

311

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

312

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

313

Child sex rings.  

PubMed Central

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 "family friend" or obtained a position of authority over children. Secrecy was encouraged and bribery, threats, and peer pressure used to induce participation in sexual activities. Offences reported included fondling, masturbation, pornography, and oral, vaginal, and anal intercourse. Eleven perpetrators were successfully prosecuted; all but one received a sentence of three years or less. Behavioural problems were common among those children who had participated for a long time. Child sex rings are difficult to detect and may be common. Many children are seriously abused as a consequence of them. PMID:3730803

Wild, N J; Wynne, J M

1986-01-01

314

One-Step Hydrothermal Synthesis of Comb-Like ZnO Nanostructures Xiaobin Xu,  

E-print Network

One-Step Hydrothermal Synthesis of Comb-Like ZnO Nanostructures Xiaobin Xu, Min Wu,§ Michael Asoro in the synthesis of ZnO nanostructures has been demonstrated. Such ZnO NSSs can be fabricated on various rigid/seeds of gold (Au) or ZnO nanodots dispersed on the surface of the ZnO nanowires. This method requires a complex

Ferreira, Paulo J.

315

Polypeptide grafted hyaluronan: A self-assembling comb-branched polymer constructed from biological components  

PubMed Central

Rheological evidence is provided demonstrating that covalent grafting of monodisperse isotactic poly(L-leucine) branches onto linear hyaluronan (HA) polysaccharide chains yields comb-branched HA chains that self-assemble into long-lived physical networks in aqueous solutions driven by hydrophobic interactions between poly(L-leucine) chains. This is in stark contrast to native (unmodified) HA solutions which exhibit no tendency to form long-lived physical networks. PMID:22021933

Kandadai, Madhuvanthi A.; Anumolu, Rajasekhar; Wang, Xiaojun; Baskaran, Durairaj; Pease, Leonard F.; Bedrov, Dmitry; Smith, Grant D.; Mays, Jimmy W.; Magda, Jules J.

2011-01-01

316

A Design Method of In-plane MEMS Electret Energy Harvester with Comb Drives  

NASA Astrophysics Data System (ADS)

In this report, a design method is proposed for in-plane MEMS electrostatic energy harvesters with comb drives. Dependent on the device layer thickness and the achievable aspect ratio of the DRIE process, either the overlapping-area-change or the gap-closing converter has higher output power than the other. Two prototypes of MEMS electret energy harvesters are developed to verify the present design method.

Fu, Qianyan; Suzuki, Yuji

2014-11-01

317

Molecular combing in studies of the genome organization and DNA replication  

Microsoft Academic Search

Molecular combing (MC) yields preparations where individual DNA molecules are uniformly stretched and are parallel to each\\u000a other. Fluorescence in situ hybridization on such preparations allows an exact mapping of DNA sequences, and pulsed incorporation\\u000a of halogenated deoxyuridine analogs and their detection using fluorochrome-conjugated antibodies makes it possible to visualize\\u000a replication. The MC technique was adapted for studying DNA replication

T. D. Kolesnikova; S. A. Demakov; A. V. Ivankin; I. F. Zhimulev

2010-01-01

318

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.

2013-06-17

319

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

320

Preparation and properties of comb-like surfactants containing poly(ethylene oxide) methyl ether grafts.  

PubMed

The comb-like surfactants, poly(styrene-co-maleic anhydride)-g-(poly(ethylene glycol) monomethyl ether), poly(St-co-MA)-g-(MPEG), have been prepared using a macromonomer approach to get controlled molecular structures. The macromonomer (MAMPEG) was obtained by esterification of poly(ethylene glycol) monomethyl ether with maleic anhydride. Poly(St-co-MA)-g-(MPEG) with various molar ratios of St to MAMPEG (R) were then constructed by radical copolymerization. The comb-like structures of the surfactants were confirmed by infrared and (1)H nuclear magnetic resonance spectroscopy. It is found from gel permeation chromatography characterization that the molecular weight of the surfactants increases as R increases. The polydispersity index was in the range between 1.4 and 2.0 in all the cases. The surfactants with a higher St percentage are less soluble in water due to aggregation. The value of critical aggregation concentration (CAC) and the surface tension at the CAC (gamma(CAC)) decrease as R increases. The steady-shear measurements show that the surfactant solutions at 50 g/L are dilatant fluids. In addition, it appears that there are two break points in the viscosity-shear rate curve. Both break points increase with increasing R. It can therefore be concluded that the properties of comb-like surfactants poly(St-co-MA)-g-(MPEG) are related to molecular structure. The results demonstrate that the properties of these comb-like surfactants can be tailored through appropriate molecular design. PMID:19539302

Zhang, Wei; Du, Zhiping; Chang, Chien-Hsiang; Wang, Guoyong

2009-09-15

321

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

322

High-accuracy absolute distance measurement using frequency comb referenced multiwavelength source.  

PubMed

We propose a new approach to multiple-wavelength interferometry, targeted to high bandwidth absolute distance measurement, with nanometer accuracy over long distances. Two cw lasers are stabilized over a wide range of frequency intervals defined by an optical frequency comb, thus offering an unprecedented large choice of synthetic wavelengths. By applying a superheterodyne detection technique, we demonstrated experimentally an accuracy of 8 nm over 800 mm for target velocities up to 50 mm/s. PMID:18470268

Salvadé, Yves; Schuhler, Nicolas; Lévêque, Samuel; Le Floch, Sébastien

2008-05-10

323

Reclassification of Cellulomonas cellulans (Stackebrandt and Keddie 1986) as Cellulosimicrobium cellulans gen. nov., comb. nov.  

PubMed

Phylogenetic analysis of 16S rDNA provides evidence that Cellulomonas cellulans branches outside the phylogenetic confines of the genus Cellulomonas. The distinct phylogenetic and chemotaxonomic status of Cellulomonas cellulans as a phylogenetic neighbour of the genus Promicromonospora, justifies the description of a new genus for which the name Cellulosimicrobium gen. nov. with the type species Cellulosimicrobium cellulans comb. nov. is proposed. PMID:11411667

Schumann, P; Weiss, N; Stackebrandt, E

2001-05-01

324

Optical frequency combs from semiconductor lasers and applications in ultrawideband signal processing and communications  

Microsoft Academic Search

Modelocked semiconductor lasers are used to generate a set of phase-locked optical frequencies on a periodic grid. The periodic and phase coherent nature of the optical frequency combs makes it possible for the realization of high-performance optical and RF arbitrary-waveform synthesis. In addition, the resulting optical frequency components can be used for communication applications relying on direct detection, dense wavelength

Peter J. Delfyett; Sangyoun Gee; Myoung-Taek Choi; Hossein Izadpanah; Wangkuen Lee; Sarper Ozharar; Franklyn Quinlan; Tolga Yilmaz

2006-01-01

325

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

326

Acceptable sex selection.  

PubMed

John Robertson presents a persuasive argument against government prohibition of preconception sex selection (PSS) as long as there is no actual evidence of significant social harm from allowing the technology to be freely available. I am convinced by what he says about PSS and have argued along similar lines in my own work (Rhodes 1995). In these comments, I will press Robertson's conclusion in several directions to show what more he might have said in its defense. PMID:11808590

Rhodes, R

2001-01-01

327

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

328

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

329

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

330

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

PubMed

Among living vertebrates, soft tissues are responsible for labile appendages (combs, wattles, proboscides) that are critical for activities ranging from locomotion to sexual display [1]. However, soft tissues rarely fossilize, and such soft-tissue appendages are unknown for many extinct taxa, including dinosaurs. Here we report a remarkable "mummified" specimen of the hadrosaurid dinosaur Edmontosaurus regalis from the latest Cretaceous Wapiti Formation, Alberta, Canada, that preserves a three-dimensional cranial crest (or "comb") composed entirely of soft tissue. Previously, crest function has centered on the hypertrophied nasal passages of lambeosaurine hadrosaurids, which acted as resonance chambers during vocalization [2-4]. The fleshy comb in Edmontosaurus necessitates an alternative explanation most likely related to either social signaling or sexual selection [5-7]. This discovery provides the first view of bizarre, soft-tissue signaling structures in a dinosaur and provides additional evidence for social behavior. Crest evolution within Hadrosaurinae apparently culminated in the secondary loss of the bony crest at the terminal Cretaceous; however, the new specimen indicates that cranial ornamentation was in fact not lost but substituted in Edmontosaurus by a fleshy display structure. It also implies that visual display played a key role in the evolution of hadrosaurine crests and raises the possibility of similar soft-tissue structures among other dinosaurs. PMID:24332547

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

2014-01-01

331

Frequency stabilisation of a fibre-laser comb using a novel microstructured fibre.  

PubMed

There is great interest in developing high performance optical frequency metrology based around mode-locked fibre lasers because of their low cost, small size and long-term turnkey operation when compared to the solid-state alternative. We present a method for stabilising the offset frequency of a fibre-based laser comb using a 2 f - 3 f technique based around a unique fibre that exhibits strong resonant dispersive wave emission. This fibre requires lower power than conventional highly non-linear fibre to generate a suitable signal for offset frequency stabilisation and this in turn avoids the complexity of additional nonlinear steps. We generate an offset frequency signal from the mixing of a wavelength-shifted second harmonic comb with a third harmonic of the comb. Additionally, we have stabilised the repetition rate of the laser to a level better than 10(-14)/ radicaltau , limited by the measurement system noise floor.We present the means for complete and precise measurement of the transfer function of the laser frequency controls. PMID:19333360

Locke, C R; Ivanov, E N; Light, P S; Benabid, F; Luiten, A N

2009-03-30

332

Flat optical frequency comb generation and its application for optical waveform generation  

NASA Astrophysics Data System (ADS)

We demonstrate the generation of a flat optical frequency comb (OFC) using an electro absorption modulator (EAM) and two cascaded phase modulators (PM). Compared with previous flat OFC generation schemes using a Mach-Zehnder modulator (MZM) for amplitude gating of the phase modulated light, an EAM creates much shorter time window for amplitude gating, and more flattened OFC spectrum is obtained using EAM as an amplitude gate. In our experiment, a very flat OFC having 11 lines within 3-dB bandwidth (3.8 nm), and 40 GHz comb line spacing is generated. Besides the excellent spectral flatness, the strong time-domain linear-chirp of the generated OFC can be simply compensated by a dispersion compensation fiber (DCF) link, which is preferred for optical waveform generation based on spectral manipulation. In this paper, we also demonstrate the OFC application for generation of several optical waveforms by manipulating the amplitude and phase of the comb lines. High repetition-rate optical cosine pulse, optical pulse burst, optical square and triangle pulses are successfully generated.

Zhang, Fangzheng; Wu, Jian; Li, Yan; Lin, Jintong

2013-03-01

333

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

334

Observation of Rb Two-Photon Absorption Directly Excited by an Erbium-Fiber-Laser-Based Optical Frequency Comb via Spectral Control  

E-print Network

We demonstrated the observation of Rb two-photon absorption directly excided by an optical frequency comb at fiber communication bands. A chain of comb spectral control is elaborately implemented to increase the power of the second harmonic optical frequency comb generation and the two-photon transition strength. A two-photon transition spectrum is obtained with clearly resolved transition lines. It provides a potential approach to realize the optical frequency comb or optical clock at ~1.5{\\mu}m with high stability and accuracy.

Wu, Jiutao; Dai, Xiaoliang; Qin, Zhengyu; Zhang, Zhigang; Zhao, Jianye

2013-01-01

335

Sex workers talk about sex work: six contradictory characteristics of legalised sex work in Melbourne, Australia.  

PubMed

Despite research suggesting that legal sex work is safe and that emotional risks and social stigma are of greater concern than health risks, much research on sex work has focused on health risks. Given the legalisation of sex work in Victoria, Australia, it is timely to look beyond health. Three focus groups were conducted with a total of 14 female sex workers on their experience of legal sex work, both positive and negative, and the social acceptability of their profession. Thematic analysis was used to identify the key ways that sex workers described sex work. Women saw legal sex work as safer than illegal sex work, but still not socially acceptable. However, they also described six contradictory elements of sex work, which was seen as: financially rewarding and entrapping; empowering and demeaning; increasing some opportunities while reducing others; flexible and demanding; offering both intimacy and competition; and leading to a 'double life'. While legalisation has improved the safety of sex work, stigma and discrimination persist. PMID:23173716

Begum, Sufia; Hocking, Jane S; Groves, Jan; Fairley, Christopher K; Keogh, Louise A

2013-01-01

336

Nonvolitional sex and sexual health.  

PubMed

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 behavior that masks one's nonconventional sexual identity, or that protects one's position with peers, or that represents a quid pro quo for the economic support that one obtains within an intimate relationship. The aim of this essay is to highlight the ways in which nonvolitional sex threatens sexual health and to identify strategies for ameliorating this problem. These strategies will have to be as broad in scope as is the problem that they are designed to address. The essay discusses the following strategies to reduce nonvolitional sex: (1) advocacy for sexual rights, gender equality, and equality for individuals with nonconventional sexual identities; (2) primary prevention programs and interventions that offer comprehensive sexuality education that establishes volitional sex and sexual health as basic human rights; (3) health services that routinely ask clients about their experiences with nonvolitional sex in an open and culturally appropriate manner; and (4) secondary prevention programs to meet the needs of victims of nonvolitional sex identified by the "screening" programs. PMID:15129039

Kalmuss, Debra

2004-06-01

337

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

338

Sex-linked chorioretinal heredodegenerations.  

PubMed

The sex-linked chorioretinal heredodegenerations are progressive chorioretinal degeneration or choroideremia, sex-linked pigmentary retinopathy and sex-linked choroidal sclerosis. In chroroideremia the hemizygote male is fully affected, but the female heterozygote carrier shows fundus abnormalities (irregular pigmentation of the retinal periphery). The involvement of some females can be explained by Lyon's inactivation theory. The sex-linked pigmentary retinopathy is either recessive or intermediate or exceptionally dominant. In the intermediate form the female carriers show a tapetoretinal golden reflex. The sex-linked choroidal sclerosis is probably an intermediate stage in the development of a chorioretinal degeneration into choroideremia. All these degenerations must be differentiated from ocular albinism, which is also sex-linked with clinical stigmata in the female carriers (fundus changes and iris-translucency). PMID:4950918

François, J

1971-03-01

339

Sex determination mechanisms in fish  

Microsoft Academic Search

In fish, sex determination (SD) system shows high variation. The SD mechanisms include environmental and genetic regulation.\\u000a The research on SD system and related genes in intensively studied fish species was reviewed. Although some genes have been\\u000a described as sex-related, only DMRT1bY can be considered as a master sex determination gene and none of them has been utilized in aquaculture.

Quanqi Zhang; Xiaohua Sun; Jie Qi; Zhigang Wang; Xinglian Wang; Xubo Wang; Teng Zhai

2009-01-01

340

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

341

Influence of TachoComb in comparison to local hemostyptic agents on epidural fibrosis in a rat laminectomy model.  

PubMed

This animal experimental study was designed to examine the effects of TachoComb, a fixed combination of collagen with tissue adhesive, as an interposition membrane on the development of spinal epidural fibrosis in comparison to other hemostyptic materials. In 10 Wistar rats, four laminectomies were performed at lumbar and sacral vertebrae. Alternately, a piece of TachoComb, Spongostan, or Tabotamp was placed into each laminectomy site. One laminectomy site served as an empty control (n = 10). 8 weeks later, the animals were sacrificed, and the spinal column including surrounding muscle tissue was removed en bloc from each rat and fixed in formaldehyde. After decalcification and staining the specimens were graded by a neuropathologist in a blindfold test for severity of epidural fibrosis as "light-moderate" or "marked". Epidural scarring of variable density was seen in all laminectomy sites. Light epidural fibrosis, without any adhesion to dura, as only noted in cases after application of TachoComb (n = 4/10) and Spongostan (n = 1/10). All other slices showed marked epidural fibrosis with dura adherence regardless of the implanted material. Statistical analysis revealed significantly lower epidural fibrosis after application of TachoComb compared to all other groups (p < 0.05). In this series, TachoComb is more effective in reducing the epidural fibrosis than Spongostan, and Tabotamp. However, complete prevention of scar tissue formation was not achieved. PMID:12761682

Lee, J-Y; Ebel, H; Friese, M; Schillinger, G; Schröder, R; Klug, N

2003-04-01

342

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

343

Stabilization of a self-referenced, prism-based, Cr:forsterite laser frequency comb using an intracavity prism.  

PubMed

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 approximately 2 x 10(-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 3 x 10(-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. PMID:20029601

Tillman, Karl A; Thapa, Rajesh; Knabe, Kevin; Wu, Shun; Lim, Jinkang; Washburn, Brian R; Corwin, Kristan L

2009-12-20

344

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

NASA Astrophysics Data System (ADS)

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

Yang, Xiangbo; Song, Huanhuan; Liu, Timon Chengyi

2013-12-01

345

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

346

Sex-work harm reduction.  

PubMed

Sex work is an extremely dangerous profession. The use of harm-reduction principles can help to safeguard sex workers' lives in the same way that drug users have benefited from drug-use harm reduction. Sex workers are exposed to serious harms: drug use, disease, violence, discrimination, debt, criminalisation, and exploitation (child prostitution, trafficking for sex work, and exploitation of migrants). Successful and promising harm-reduction strategies are available: education, empowerment, prevention, care, occupational health and safety, decriminalisation of sex workers, and human-rights-based approaches. Successful interventions include peer education, training in condom-negotiating skills, safety tips for street-based sex workers, male and female condoms, the prevention-care synergy, occupational health and safety guidelines for brothels, self-help organisations, and community-based child protection networks. Straightforward and achievable steps are available to improve the day-to-day lives of sex workers while they continue to work. Conceptualising and debating sex-work harm reduction as a new paradigm can hasten this process. PMID:16360791

Rekart, Michael L

2005-12-17

347

Sex Role and Depressive Mood.  

ERIC Educational Resources Information Center

Research has suggested that an association exists between sex role identity and typing and affective states. The relationship of sex role type and depressive mood was explored through the direct manipulation of affect in a mood induction procedure. Female (N=208) and male (N=131) subjects, classified as either androgynous, masculine, feminine, or…

Small, Arnold; And Others

348

Sex Roles: A Research Bibliography.  

ERIC Educational Resources Information Center

The National Institute of Mental Health recognizes the need for careful research investigations into the influences of sex roles on individual behavior and on societal institutions. During 1973 and 1974 the Institute held a series of research workshops to identify and encourage needed studies on sex roles, their biological and social bases, and…

Astin, Helen S., Comp.; And Others

349

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

350

[Sex-linked juvenile retinoschisis].  

PubMed

About 13 observations of sexe linked juvenile retinoschisis, the authors describe the ophthalmoscopic, fluorographic and functional aspects of the disease whose caracteristics are:--its sexe linked recessive heredity; --its clinical characterestics associating: a microcystic macular degeneration, peripheral retinal lesions, vitreous body alterations, --an electroretinogram of the negative type. PMID:132916

François, P; Turut, P; Soltysik, C; Hache, J C

1976-02-01

351

Viewpoints: Sex Education and Deafness.  

ERIC Educational Resources Information Center

The 10 contributed papers are intended to clarify the major issues of sex education and deafness and offer realistic responses to the expressed needs of professionals serving the deaf. Papers have the following titles and authors: "Sex Education from the Deaf Perspective" (Robert Davila); "Sexuality and Deafness: An Overview" (Max Fitz-Gerald and…

Fitz-Gerald, Della, Ed.; Fitz-Gerald, Max, Ed.

352

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

353

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

354

Improving Sex Equity. Final Report.  

ERIC Educational Resources Information Center

The University of North Texas, with the assistance of the equity coordinators of eight Texas public two-year postsecondary institutions, worked to improve sex equity programs throughout the state. First, the state's existing manual dealing with improving sex equity in postsecondary vocational-technical programs was updated to include materials…

Lovelace, Bill E.; And Others

355

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

356

Kerr parametric oscillations and frequency comb generation from dispersion compensated silica micro-bubble resonators.  

PubMed

Silica micro-bubble resonators (MBRs) with cavity quality factor as high as Q = 5 × 10(7) are fabricated. The total dispersion of MBRs is analyzed. The thin-wall structure opens a new anomalous dispersion window and thus supports the dispersion compensation for hyper-parametric frequency conversion processes. Experimentally, Kerr parametric oscillation is observed in a 136 ?m diameter MBR, frequency comb generation is also realized. Meanwhile the same nonlinear process is not allowed in solid silica spheres with size smaller than 150 ?m. PMID:23938539

Li, Ming; Wu, Xiang; Liu, Liying; Xu, Lei

2013-07-15

357

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

358

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

359

A signal processing system of remote sensing infrared camera based on oversample and comb filter  

NASA Astrophysics Data System (ADS)

Remote sensing infrared camera is two-dimensional thermal imaging equipment. In this paper, a new data acquiring and processing system of TDI infrared detector is given. This system is consisted of FPGA, ADC, SRAM memory, and so on. Low-pass filtering, pixel response non-uniformity correction, data synthesis and conversion of data output is implemented by a single FPGA. The SNR is improved by denoising algorithm based on oversample and comb filter. This system is easy to implement and can be applied in imaging device widely. The performance of imaging system is improved.

Lei, Ning; Wei, Zhiyong; Wang, Hua; Li, Tao

2012-12-01

360

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

361

Experimental realization of multipartite entanglement of 60 modes of a quantum optical frequency comb.  

PubMed

We report the experimental realization and characterization of one 60-mode copy and of two 30-mode copies of a dual-rail quantum-wire cluster state in the quantum optical frequency comb of a bimodally pumped optical parametric oscillator. This is the largest entangled system ever created whose subsystems are all available simultaneously. The entanglement proceeds from the coherent concatenation of a multitude of Einstein, Podolsky, and Rosen pairs by a single beam splitter, a procedure which is also a building block for the realization of hypercubic-lattice cluster states for universal quantum computing. PMID:24724640

Chen, Moran; Menicucci, Nicolas C; Pfister, Olivier

2014-03-28

362

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

363

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

364

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.

365

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

366

Effect of surface acoustic waves on the catalytic decomposition of ethanol employing a comb transducer for ultrasonic generation  

SciTech Connect

The effect of surface acoustic waves, generated on a silver catalyst using a comb transducer, on the catalytic decomposition of ethanol is examined. The comb transducer employs purely mechanical means for surface acoustic wave (SAW) transduction. Unlike interdigital SAW transducers on piezoelectric substrates, the complicating effects of heat generation due to electromechanical coupling, high electric fields between adjacent electrodes, and acoustoelectric currents are avoided. The ethanol decomposition reactions are carried out at 473 K. The rates of acetaldehyde and ethylene production are retarded when acoustic waves are applied. The rates recover to varying degrees when acoustic excitation ceases.

S. J. Reese; D. H. Hurley; H.W. Rollins

2006-04-01

367

High-stability microwave frequency transfer by propagation of an optical frequency comb over 50 km of optical fiber.  

PubMed

A high-stability microwave frequency reference is transferred over 50 km of spooled optical fiber by propagation of a 90-nm-wide optical frequency comb centered at 1.56 microm. Environmentally induced fiber phase noise is actively suppressed by returning the optical frequency comb via a separate fiber. The stability of the microwave frequency delivered is measured at the "user" end, eliminating the need for the assumption of correlation between the noise in the forward and return paths. The measured transfer stability is 4.6 x 10(-15)tau(-1), rendering this technique suitable for the transfer of state-of-the-art frequency references. PMID:20364205

Marra, Giuseppe; Margolis, Helen S; Lea, Stephen N; Gill, Patrick

2010-04-01

368

The sex and sex determination in Pyropia haitanensis (Bangiales, Rhodophyta).  

PubMed

Pyropia haitanensis has a biphasic life cycle with macroscopic gametophytic blade (n) and microscopic filamentous conchocelis (2n) phase. Its gametophytic blades have long been believed to be mainly dioecious. However, when crossing the red mutant (R, ?) with the wild type (W, ?), the parental colors were segregated in F1 blades, of which 96.1% were linearly sectored with 2-4 color sectors. When color sectors were excised from the color-sectored blades and cultured singly, 99.7% of the color sectors appeared to be unisexual with an equal sex ratio. Although the sex of color sector did not genetically link with its color, the boundaries of both sex and color sectors coincided precisely. About 87.9% of the examined color-sectored blades were monoecious and the percentage increased with the number of color sectors of a blade. The gametophytic blades from each conchocelis strain produced by parthenogenesis of the excised color sectors were unisexual and unicolor, showing the same sex and color as their original sectors. These results indicate that most of the sexually reproduced Py. haitanensis blades are monoecious, and their sex is controlled by segregation of a pair of alleles during meiosis of conchospore, forming a sex-sectored tetrad. During the subsequent development of blades, one or two lower cell(s) of the tetrad contribute mainly to rhizoid formation, and rarely show their sexual phenotype, leading to reduced frequency of full sex phenotype of the meiotic blades. Moreover, the aberrant segregations of sex genes or color genes in a few of F1 blades were probably due to gene conversions, but there was no sex transfer in Py. haitanensis. PMID:23991194

Zhang, Yuan; Yan, Xing-hong; Aruga, Yusho

2013-01-01

369

Risk Comparison among Youth Who Report Sex with Same-Sex versus Both-Sex Partners  

ERIC Educational Resources Information Center

This article examines risk behavior among youth attending support groups for sexual minority youth in Richmond, Virginia, using a structured survey, with particular attention to partner selection and its relationship to risk. Within this generally high-risk group, youth reporting sex partners of both sexes had significantly higher risk profiles,…

Moon, Martha W.; Fornili, Katherine; O'Briant, Amanda L.

2007-01-01

370

Extremely high-accuracy correction of air refractive index using two-colour optical frequency combs  

PubMed Central

Optical frequency combs have become an essential tool for distance metrology, showing great advantages compared with traditional laser interferometry. However, there is not yet an appropriate method for air refractive index correction to ensure the high performance of such techniques when they are applied in air. In this study, we developed a novel heterodyne interferometry technique based on two-colour frequency combs for air refractive index correction. In continuous 500-second tests, a stability of 1.0 × 10?11 was achieved in the measurement of the difference in the optical distance between two wavelengths. Furthermore, the measurement results and the calculations are in nearly perfect agreement, with a standard deviation of 3.8 × 10?11 throughout the 10-hour period. The final two-colour correction of the refractive index of air over a path length of 61 m was demonstrated to exhibit an uncertainty better than 1.4 × 10?8, which is the best result ever reported without precise knowledge of environmental parameters. PMID:23719387

Wu, Guanhao; Takahashi, Mayumi; Arai, Kaoru; Inaba, Hajime; Minoshima, Kaoru

2013-01-01

371

Gigahertz self-referenceable frequency comb from a semiconductor disk laser.  

PubMed

We present a 1.75-GHz self-referenceable frequency comb from a vertical external-cavity surface-emitting laser (VECSEL) passively modelocked with a semiconductor saturable absorber mirror (SESAM). The VECSEL delivers 231-fs pulses with an average power of 100 mW and is optimized for stable and reliable operation. The optical spectrum was centered around 1038 nm and nearly transform-limited with a full width half maximum (FWHM) bandwidth of 5.5 nm. The pulses were first amplified to an average power of 5.5 W using a backward-pumped Yb-doped double-clad large mode area (LMA) fiber and then compressed to 85 fs with 2.2 W of average power with a passive LMA fiber and transmission gratings. Subsequently, we launched the pulses into a highly nonlinear photonic crystal fiber (PCF) and generated a coherent octave-spanning supercontinuum (SC). We then detected the carrier-envelope offset (CEO) frequency (f(CEO)) beat note using a standard f-to-2f-interferometer. The f(CEO) exhibits a signal-to-noise ratio of 17 dB in a 100-kHz resolution bandwidth and a FWHM of ?10 MHz. To our knowledge, this is the first report on the detection of the f(CEO) from a semiconductor laser, opening the door to fully stabilized compact frequency combs based on modelocked semiconductor disk lasers. PMID:24977894

Zaugg, Christian A; Klenner, Alexander; Mangold, Mario; Mayer, Aline S; Link, Sandro M; Emaury, Florian; Golling, Matthias; Gini, Emilio; Saraceno, Clara J; Tilma, Bauke W; Keller, Ursula

2014-06-30

372

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

373

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

374

Ultra-Low Phase Noise, High Resolution Spectrometer Using Comb-Assisted Quantum Cascade Lasers  

NASA Astrophysics Data System (ADS)

In recent years, optical frequency combs have been used extensively to stabilize solid state cw lasers for high resolution spectroscopy, enabling the acquisition of absorption profiles of a gas sample with an absolutely calibrated, repeatable and linear frequency axis. This uniquely defined and repeatable frequency axis allows for the retrieval of highly accurate and traceable spectroscopic parameters and the ability to obtain physical insights regarding the influence of collisional processes on the absorption line shapes. The highly accurate frequency axis has can be used in precision spectroscopy applications such as resolving hyperfine transitions or cavity enhanced spectroscopy for trace gas detection. To simplify such precision spectroscopy systems in the future, the use of quantum cascade lasers (QCL) as a spectroscopic tool is highly desired. Here we report on the precision phase locking of a 9 ?m QCL to a 2 ?m low-noise thulium frequency comb. Utilizing a coherent lock with a MHz-level feedback bandwidth, we line narrow a QCL with a 1 MHz linewidth and achieve an in-loop beatnote measurement with 70 dB S/N at 1 Hz RBW. As an application, we demonstrate the interrogation of sub-Doppler features of ammonia spectra at 9 ?m. It is expected that the system is further compatible with line narrowing of widely tunable external cavity QCL's, opening new measurement avenues in precision spectroscopy.

Mills, Andrew A.; Mohr, Christian; Jiang, Jie; Gatti, Davide; Marangoni, Marco; Gianfrani, Livio; Hartl, Ingmar; Fermann, Martin

2013-06-01

375

Comb jellies (ctenophora): a model for Basal metazoan evolution and development.  

PubMed

INTRODUCTIONCtenophores, or comb jellies, are a group of marine organisms whose unique biological features and phylogenetic placement make them a key taxon for understanding animal evolution. These gelatinous creatures are clearly distinct from cnidarian medusae (i.e., jellyfish). Key features present in the ctenophore body plan include biradial symmetry, an oral-aboral axis delimited by a mouth and an apical sensory organ, two tentacles, eight comb rows composed of interconnected cilia, and thick mesoglea. Other morphological features include definitive muscle cells, a nerve net, basal lamina, a sperm acrosome, and light-producing photocytes. Aspects of their development made them attractive to experimental embryologists as early as the 19th century. Recently, because of their role as an invasive species, studies on their role in ecology and fisheries-related fields have increased. Although the phylogenetic placement of ctenophores with respect to other animals has proven difficult, it is clear that, along with poriferans, placozoans, and cnidarians, ctenophores are one of the earliest diverging extant animal groups. It is important to determine if some of the complex features of ctenophores are examples of convergence or if they were lost in other animal branches. Because ctenophores are amenable to modern technical approaches, they could prove to be a highly useful emerging model. PMID:21356709

Pang, Kevin; Martindale, Mark Q

2008-01-01

376

Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb  

E-print Network

One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexing in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.

Raphael Pooser; Jietai Jing

2014-06-25

377

A charge optimized many-body (comb) potential for titanium and titania  

NASA Astrophysics Data System (ADS)

This work proposes an empirical, variable charge potential for Ti and TiO2 systems based on the charge-optimized many-body (COMB) potential framework. The parameters of the potential function are fit to the structural and mechanical properties of the Ti hcp phase, the TiO2 rutile phase, and the energetics of polymorphs of both Ti and TiO2. The relative stabilities of TiO2 rutile surfaces are predicted and compared to the results of density functional theory (DFT) and empirical potential calculations. The transferability of the developed potential is demonstrated by determining the adsorption energy of Cu clusters of various sizes on the rutile TiO2(1?1?0) surface using molecular dynamics simulations. The results indicate that the adsorption energy is dependent on the number of Cu-Cu bonds and Cu-O bonds formed at the Cu/TiO2 interface. The adsorption energies of Cu clusters on the reduced and oxidized TiO2(1?1?0) surfaces are also investigated, and the COMB potential predicts enhanced bonding between Cu clusters and the oxidized surface, which is consistent with both experimental observations and the results of DFT calculations for other transition metals (Au and Ag) on this oxidized surface.

Cheng, Yu-Ting; Shan, Tzu-Ray; Liang, Tao; Behera, Rakesh K.; Phillpot, Simon R.; Sinnott, Susan B.

2014-08-01

378

A charge optimized many-body (COMB) potential for titanium and titania.  

PubMed

This work proposes an empirical, variable charge potential for Ti and TiO(2) systems based on the charge-optimized many-body (COMB) potential framework. The parameters of the potential function are fit to the structural and mechanical properties of the Ti hcp phase, the TiO(2) rutile phase, and the energetics of polymorphs of both Ti and TiO(2). The relative stabilities of TiO(2) rutile surfaces are predicted and compared to the results of density functional theory (DFT) and empirical potential calculations. The transferability of the developed potential is demonstrated by determining the adsorption energy of Cu clusters of various sizes on the rutile TiO(2)(1?1?0) surface using molecular dynamics simulations. The results indicate that the adsorption energy is dependent on the number of Cu-Cu bonds and Cu-O bonds formed at the Cu/TiO(2) interface. The adsorption energies of Cu clusters on the reduced and oxidized TiO(2)(1?1?0) surfaces are also investigated, and the COMB potential predicts enhanced bonding between Cu clusters and the oxidized surface, which is consistent with both experimental observations and the results of DFT calculations for other transition metals (Au and Ag) on this oxidized surface. PMID:24943265

Cheng, Yu-Ting; Shan, Tzu-Ray; Liang, Tao; Behera, Rakesh K; Phillpot, Simon R; Sinnott, Susan B

2014-08-01

379

Coherent control of neutral atoms on chip traps using optical frequency combs  

NASA Astrophysics Data System (ADS)

Optical frequency combs (OFCs), emitted by ultrafast modelocked pulsed lasers, are excellent tools to perform quantum coherent control. The spectral purity, large bandwidth and high pulse powers makes these sources attractive for precision control of multi-level atoms. Recent experiments have shown that an OFC can be used to coherently control and entangle trapped ion qubits by means of off-resonant Raman transitions [1]. Here, we propose to extend this technique to neutral atoms confined on an atom chip and we also propose to implement an all-optical technique for hyperfine qubit manipulation using OFCs. We envisage using pairs of OFC modes to drive stimulated Raman transitions between the two hyperfine clock states of 87Rb confined on an atom chip. The Raman transitions will be driven using a four photon technique whereby the first photon pair drives off-resonantly to the intermediate state 2S1/2 |F=2, mf=0> and then a second photon pair resonantly drives to 2S1/2 |F=2, mf=+1>. Co-propagating Raman fields impart only a spin flip whereas non-copropagating fields transfer two photon recoil momentum to the atoms, thus entangling the internal spin with the external motion of the atoms. We plan on using the frequency comb to impart state dependent forces to the atomic cloud.

Quraishi, Qudsia; Malinovsky, Vladimir; Alexander, Jason; Prieto, Violeta; Rowlett, Chris; Lee, Patricia

2011-06-01

380

Global phase and frequency comb structures in nonlinear Compton and Thomson scattering  

E-print Network

The Compton and Thomson radiation spectra, generated in collisions of an electron beam with a powerful laser beam, are studied in the framework of quantum and classical electrodynamics, respectively. We show that there are frequency regimes where both radiation spectra are nearly identical, which for Compton scattering relates to the process which preserves the electron spin. Although the radiation spectra are nearly identical, the corresponding probability amplitudes exhibit different global phases. This has pronounced consequences, which we demonstrate by investigating temporal power distributions in both cases. We show that, contrary to Thomson scattering, it is not always possible to synthesize short laser pulses from Compton radiation. This happens when the global phase of the Compton amplitude varies in a nonlinear way with the frequency of emitted photons. We also demonstrate that while the Compton process driven by a non-chirped laser pulse can generate chirped bursts of radiation, this is not the case for the Thomson process. In principle, both processes can lead to a generation of coherent frequency combs when single or multiple driving laser pulses collide with electrons. Once we synthesize these combs into short bursts of radiation, we can control them, for instance, by changing the time delay between the driving pulses.

K. Krajewska; M. Twardy; J. Z. Kami?ski

2014-03-17

381

Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb  

SciTech Connect

One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexing in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.

Pooser, Raphael C [ORNL; Jing, Jietai [East China Normal University (ECNU)

2014-01-01

382

Continuous Variable Cluster State Generation over the Optical Spatial Mode Comb  

E-print Network

One way quantum computing uses single qubit projective measurements performed on a cluster state (a highly entangled state of multiple qubits) in order to enact quantum gates. The model is promising due to its potential scalability; the cluster state may be produced at the beginning of the computation and operated on over time. Continuous variables (CV) offer another potential benefit in the form of deterministic entanglement generation. This determinism can lead to robust cluster states and scalable quantum computation. Recent demonstrations of CV cluster states have made great strides on the path to scalability utilizing either time or frequency multiplexing in optical parametric oscillators (OPO) both above and below threshold. The techniques relied on a combination of entangling operators and beam splitter transformations. Here we show that an analogous transformation exists for amplifiers with Gaussian inputs states operating on multiple spatial modes. By judicious selection of local oscillators (LOs), the spatial mode distribution is analogous to the optical frequency comb consisting of axial modes in an OPO cavity. We outline an experimental system that generates cluster states across the spatial frequency comb which can also scale the amount of quantum noise reduction to potentially larger than in other systems.

Raphael Pooser; Jietai Jing

2014-12-30

383

Sex work and the law.  

PubMed

We reviewed publications, websites, and field observations to explore the health and welfare impacts and administrative effectiveness of different legal approaches to sex work. We identified three broad legal approaches: (1) prohibition, including the unique Swedish law criminalising sex workers' clients; (2) licensing; and (3) decriminalisation. Each of these models is employed under one or more jurisdictions in Australia. We make preliminary observations on their consequences and conclude that, on initial impression, decriminalisation may offer the best outcomes. However, more rigorous population-based research is needed to properly assess the health and welfare impacts of legal approaches to sex work. PMID:16335539

Harcourt, Christine; Egger, Sandra; Donovan, Basil

2005-01-01

384

Sex in the mucoralean fungi.  

PubMed

Sexual development is extant in virtually all eukaryotic species, including throughout the kingdom Fungi. Positioned within the opisthokonts along with metazoans, fungi serve as model systems to elucidate the genetics and impact of sexual development. Basal fungal lineages such as the Mucoralean fungi provide a unique basis to study sexual reproduction, in which common ancestral traits found in both animal and fungal lineages may be conserved. This review discusses the sexual development, sex loci, and evolution of the sex locus in the Mucoralean fungi, which sheds light on our understanding of the evolution and functions of sex. PMID:25175551

Lee, Soo Chan; Heitman, Joseph

2014-12-01

385

Whose crazy investment in sex?  

PubMed

By probing the processes of exclusion of transsexuals from the political sphere, this article offers contributions to social and political theory through an examination of the processes of exclusion from the category "human." This article considers how the erasure of investment in their own embodied sex constructs a platform from which to blame others for sex/gender variance, as well as to justify that blaming. Bringing together Giorgio Agamben, Georges Bataille, Judith Butler, and Nikolas Rose with transphobia, medicalization in psychiatry, law, and ethopolitics, this article questions whose investment in sexed embodiment counts and why that investment might be seen as "crazy." PMID:21294026

Mandlis, Lane R

2011-01-01

386

Classifying sex biased congenital anomalies  

SciTech Connect

The reasons for sex biases in congenital anomalies that arise before structural or hormonal dimorphisms are established has long been unclear. A review of such disorders shows that patterning and tissue anomalies are female biased, and structural findings are more common in males. This suggests different gender dependent susceptibilities to developmental disturbances, with female vulnerabilities focused on early blastogenesis/determination, while males are more likely to involve later organogenesis/morphogenesis. A dual origin for some anomalies explains paradoxical reductions of sex biases with greater severity (i.e., multiple rather than single malformations), presumably as more severe events increase the involvement of an otherwise minor process with opposite biases to those of the primary mechanism. The cause for these sex differences is unknown, but early dimorphisms, such as differences in growth or presence of H-Y antigen, may be responsible. This model provides a useful rationale for understanding and classifying sex-biased congenital anomalies. 42 refs., 7 tabs.

Lubinsky, M.S. [Medical College of Wisconsin and Children`s Hospital, Milwaukee, WI (United States)] [Medical College of Wisconsin and Children`s Hospital, Milwaukee, WI (United States)

1997-03-31

387

Sex and Violence in Neuroscience.  

ERIC Educational Resources Information Center

Describes advances made in the understanding of how sex hormones may modify various cognitive skills, how normal brain signaling mechanisms may cause nerve cell death, and how many cells appear to hold genetic agents which determine their own destruction. (RT)

Barnes, Deborah M.

1988-01-01

388

Sex Work: A Comparative Study  

E-print Network

poverty, associations with “pimps” and other exploiters, homelessness, and drug use.poverty, abuse, and family instability were independently associated with adult sex work, as were limited education and employment experience, adult drug use,

McCarthy, Bill

2014-01-01

389

Identification of TIR-Domain Containing Genes and Proteins in the Moon (Aurelia Aurita) and Comb Jellyfish (Mnemiopsis Leidyi)  

Microsoft Academic Search

The discovery of Toll-like receptors (TLRs) in Drosophila and their subsequent discovery in humans has piqued the scientific community's interest in their evolution. Marine invertebrates are now starting to become model organisms for the evolution of immunity and for immunological disease therapeutics. This study sought to determine the identification of a TLR receptor in the comb jellyfish and moon jellyfish

Christine M. Turcotte

2011-01-01

390

Plastic (wire-combed) grooving of a slip-formed concrete runway overlay at Patrick Henry Airport: An initial evaluation  

NASA Technical Reports Server (NTRS)

A wire-comb technique is described for transversely grooving the surface of a freshly laid (plastic state) slip-formed concrete overlay installed at Patrick Henry Airport. This method of surface texturing yields better water drainage and pavement skid resistance than that obtained with an older conventional burlap drag concrete surface treatment installed on an adjacent portion of the runway.

Marlin, E. C.; Horne, W. B.

1977-01-01

391

A gigahertz multimode-diode-pumped Yb:KGW enables a strong frequency comb offset beat signal.  

PubMed

A high-power gigahertz SESAM modelocked Yb:KGW laser is pumped with a commercial multimode diode laser and enables a strong frequency comb offset beat signal without additional amplification or pulse compression. The ultrafast Yb:KGW solid-state laser oscillator generates 125-fs pulses at an average power of 3.4 W and a repetition rate of 1.06 GHz with a record-high peak power of 22.7 kW. An octave-spanning frequency comb was generated with a 1-m long highly nonlinear photonic crystal fiber (PCF) launching only 900 mW of the total average power with a PCF coupling efficiency of 70%. The frequency comb offset was successfully detected with a carrier-envelope offset (CEO) frequency beat signal of 30-dB signal-to-noise ratio for a resolution bandwidth of 100 kHz. The robust and simple pumping scheme based on a commercially available multimode diode laser makes this laser attractive for future frequency comb metrology applications. PMID:23609745

Klenner, Alexander; Golling, Matthias; Keller, Ursula

2013-04-22

392

Abstract--A novel multiwavelength erbium-doped fiber laser (EDFL) based on two comb filters is proposed and  

E-print Network

Abstract-- A novel multiwavelength erbium-doped fiber laser (EDFL) based on two comb filters broadening of the erbium-doped fiber (EDF). As a result, triple-wavelength lasing operation with wavelengthB. I. INTRODUCTION Multiwavelength erbium-doped fiber lasers (EDFLs) are useful light sources for WDM

Wai, Ping-kong Alexander

393

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

E-print Network

June 2010 A 12.5 GHz-spaced optical frequency comb locked to a global positioning system disciplined is bounded by 30 kHz corresponding to a radial velocity of 5 cm/s , limited by the global positioning system

394

Wax Inhibition by Comb-like Polymers: Support of the Incorporation-Perturbation Mechanism from Molecular Dynamics Simulations  

E-print Network

Wax Inhibition by Comb-like Polymers: Support of the Incorporation-Perturbation Mechanism from ReceiVed: April 10, 2007; In Final Form: July 26, 2007 Deposition of wax on a cold surface is a serious problem in oil production. Progress in developing more effective wax inhibitors has been impeded

Goddard III, William A.

395

Frequency comb-based multiple-access ultrastable frequency dissemination with 7??×??10?-?17 instability.  

PubMed

In this letter, we demonstrate frequency-comb-based multiple-access ultrastable frequency dissemination over a 10-km single-mode fiber link. First, we synchronize optical pulse trains from an Er-fiber frequency comb to the remote site by using a simple and robust phase-conjugate stabilization method. The fractional frequency-transfer instability at the remote site is 2.6×10-14 and 4.9×10-17 for averaging times of 1 and 10,000 s, respectively. Then, we reproduce the harmonic of the repetition rate from the disseminated optical pulse trains at an arbitrary point along the fiber link to test comb-based multiple-access performance, and demonstrate frequency instability of 4×10-14 and 7×10-17 at 1 and 10,000 s averaging time, respectively. The proposed comb-based multiple-access frequency dissemination can easily achieve highly stable wideband microwave extraction along the whole link. PMID:25531602

Zhang, Shuangyou; Zhao, Jianye

2015-01-01

396

Odontometric sex assessment in Indians.  

PubMed

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 researchers have advocated the need for population-specific data. No odontometric standards exist for Indians for use in forensic sex prediction. Therefore, this study examined sexual dimorphism in Indians using univariate and multivariate statistics. Mesiodistal (MD) and buccolingual (BL) measurements of all teeth, except third molars, were obtained on dental casts of [corrected] 105 Indians (52 females, 53 males). The canines were [corrected] found to be the most dimorphic tooth, followed by the [corrected] BL dimensions of [corrected]first molars and that of mandibular second premolars. In general, mandibular teeth and BL dimensions showed greater tendency to be larger in males. However, just over a quarter of the measured variables (16/56; 28.6%) were statistically larger in males (p < 0.05). Moreover, ten tooth variables exhibited reverse dimorphism, i.e. female dimensions were larger than those of males. Stepwise discriminant function analysis revealed moderate accuracy in sex prediction: the teeth from both jaws taken together were able to determine sex to higher levels (76.2%) compared to only mandibular teeth (72.4%) or only maxillary teeth (67.6%). Interestingly, teeth that contributed to the stepwise discriminant analysis were either statistically larger in males or exhibited reverse dimorphism, indicating that such tooth variables may have better ability to correctly identify sex. [corrected] PMID:19744808

Prabhu, Sudeendra; Acharya, Ashith B

2009-11-20

397

Temperature-Dependent Sex Determination in Turtles  

Microsoft Academic Search

The sex of hatchling map turtles is determined by incubation temperature of eggs in the laboratory as well as in nature. Temperature controls sex differentiation rather than causing a differential mortality of sexes. Temperature has no effect on sex determination in a soft-shelled turtle.

J. J. Bull; R. C. Vogt

1979-01-01

398

When Street Sex Workers Are Mothers  

Microsoft Academic Search

Many women who engage in street sex work experience pregnancies and become mothers. Unfortunately, little research has examined how their pregnancies and parenting impact themselves as street sex workers and their street sex work. In this qualitative research study, 16 mothers who were currently involved in street sex work in a Midwestern city of the United States participated in semistructured

Christine M. Sloss; Gary W. Harper

2004-01-01

399

Money Talks: Female Sex Tourism in Jamaica  

Microsoft Academic Search

The issue of sex tourism is one that is most frequently explored as a gendered practice involving relationships between male tourists and female sex workers. By using the case of sex tourism in Jamaica, this article explores the fluidity of gender roles in an environment where foreign female tourists exchange money or material goods for sex with local males. I

Lauren C. Johnson

400

Frequency-stabilized 1 W optical comb at 2.2-2.6 ?m by Cr2+:ZnSe multipass amplification.  

PubMed

We present a frequency comb source with power level up to 150 ?W per comb mode, tunable in the 2.2-2.6 ?m wavelength region, based on a Cr(2+):ZnSe multipass solid-state amplifier seeded by the output of an actively stabilized optical parametric oscillator, synchronously pumped by a commercial 250 MHz Er:fiber laser. Phase relationship between idler, signal, and pump waves is exploited to perform frequency comb stabilization in the whole 2.2-2.6 ?m mid-infrared spectral region. PMID:23114322

Coluccelli, Nicola; Gambetta, Alessio; Sala, Tommaso; Gatti, Davide; Marangoni, Marco; Laporta, Paolo; Galzerano, Gianluca

2012-11-01

401

PAA/PEO comb polymer effects on the rheological property evolution in concentrated cement suspensions  

NASA Astrophysics Data System (ADS)

We have studied the behavior of polyelectrolyte-based comb polymers in dilute solution and on the rheological property evolution of concentrated Portland cement suspensions. These species consisted of charge-neutral, poly(ethylene oxide) (PEO) "teeth" grafted onto a poly(acrylic acid) (PAA) "backbone" that contains one ionizable carboxylic acid group (COOH) per monomer unit. As a benchmark, our observations were compared to those obtained for pure cement pastes and systems containing pure polyelectrolyte species, i.e., sulfonated naphthalene formaldehyde (SNF) and poly(acrylic acid) (PAA). The behavior of PAA/PEO comb polymers, SNF, and PAA in dilute solution was studied as a function of pH in the absence and presence of mono-, di-, and trivalent counterions. Light scattering and turbidity measurements were carried out to assess their hydrodynamic radius and stability in aqueous solution, respectively. PAA experienced large conformational changes as a function of solution pH and ionic strength. Moreover, dilute solutions of ionized SNF and PAA species became unstable in the presence of multivalent counterions due to ion-bridging interactions. PAA/PEO solutions exhibited enhanced stability relative to pure polyelectrolytes under analogous conditions. The charge neutral PEO teeth shielded the underlying PAA backbone from ion-bridging interactions. In addition, such species hindered conformational changes in solution due to steric interactions between adjacent teeth. A new oscillatory shear technique was developed to probe the rheological property evolution of concentrated cement systems. The rheological property evolution of ordinary and white Portland cement systems were studied in the absence and presence of pure polyelectrolytes and PAA/PEO comb polymers with a wide range of PAA backbone molecular weight, PEO teeth molecular weight, and acid:imide ratio. Cement-PAA suspensions experienced rapid irreversible stiffening and set at 6 min due to ion-bridging interactions between the PAA-coated particles and dissolved Ca2+ counterions. In contrast, the presence of charge-neutral PEO teeth mitigated deleterious ion interactions, promoting reversible gel-like behavior in cement-PAA/PEO suspensions over a long time scale where pure PAA fails. In cement-PAA/PEO suspensions, hydration phenomena impacted interparticle forces during early stage hydration and, ultimately, led to initial setting through the formation of solid bridges at the contact points between particles within the gelled network.

Kirby, Glen Harold

402

Sex-biased gene expression at homomorphic sex chromosomes in emus and its implication for  

E-print Network

Sex-biased gene expression at homomorphic sex chromosomes in emus and its implication for sex York, NY, and approved March 8, 2013 (received for review October 1, 2012) Sex chromosomes originate for a loss of recombination and sets in motion the evolutionary processes generating heteromorphic sex

Nachman, Michael

403

Do not have any sex (oral, vaginal, anal or using sex  

E-print Network

Do not have any sex (oral, vaginal, anal or using sex toys) with a partner until their treatment has also been completed Prevention Preventing Chlamydia · Use condoms every time you have sex sex (oral, vaginal, anal or using sex toys) with a partner until their treatment has also been

Talbot, James P.

404

Setting Occupational Sex Segregation in Motion: Demand-Side Explanations of Sex Traditional Employment  

Microsoft Academic Search

The employment of women in female-dominated occupations and men in male-dominated occu- pations (sex traditional employment) is a fundamental source of economic sex inequality. Despite this, we know little about how organizational practices and policies link workers to sex traditional jobs. The author tests theoretically hypothesized determinants of sex traditional employment using data on the sex of the last hire

JULIE A. KMEC

2005-01-01

405

Mechanisms of Disease: transcription factors in sex determination—relevance to human disorders of sex development  

Microsoft Academic Search

Sex determination is the series of molecular events that direct the undifferentiated bipotential gonad to become either a testis or an ovary. In humans, disruption of this process results in intersexuality, also referred to as disorders of sex development (DSD). Despite the discovery of the sex-determining gene SRY (sex-determining region Y) 15 years ago, the molecular mechanisms of sex determination

Ganka Nikolova; Eric Vilain

2006-01-01

406

The Stability of Same-Sex Cohabitation, Different-Sex Cohabitation, and Marriage  

ERIC Educational Resources Information Center

This study contributes to the emerging demographic literature on same-sex couples by comparing the level and correlates of union stability among 4 types of couples: (a) male same-sex cohabitation, (b) female same-sex cohabitation, (c) different-sex cohabitation, and (d) different-sex marriage. The author analyzed data from 2 British birth cohort…

Lau, Charles Q.

2012-01-01

407

Phenotypic vs. genotypic sex and cognitive abilities.  

PubMed

As a test of whether sex differences in cognitive functioning are determined by chromosomal constitution or hormonal events, eight subjects whose phenotypic sex differed from their genotypic sex were given a standard intelligence test. The results indicated that differences between verbal and nonverbal abilities corresponded to phenotypic rather than genotypic sex. The roles of environmental factors, sex steroid hormones and alternate genetic mechanisms in determining intellectual dimorphisms are examined. PMID:518470

Rovet, J; Netley, C

1979-07-01

408

Properties of ultrasonic acoustic resonances for exploitation in comb construction by social hornets and honeybees  

NASA Astrophysics Data System (ADS)

Physical and mathematical considerations are presented in support of the suggestion that social hornets and bees, which construct brood combs with large arrays of cells in a honeycomb structure, exploit ultrasonic acoustic resonances in those cells in order to achieve the great accuracy of the hexagonal symmetry exhibited by these honeycomb-structured arrays. We present a numerical calculation of those resonances for the case of a perfect-hexagon duct utilizing a Bloch-Floquet-type theorem. We calculate the rate of energy dissipation in those resonances and use that, along with other considerations, to identify the resonance that is best suited for the suggested use by bees and hornets. Previously recorded ultrasonic data on social hornets and honeybees are cited which agree with some of our predictions and thus provide support for the above-mentioned suggestion.

Kadmon, Jonathan; Ishay, Jacob S.; Bergman, David J.

2009-06-01

409

Coarse-Frequency-Comb Multiple-Beam Interferometry: Phase Assessment Using Common Phase Shifting Procedures  

NASA Astrophysics Data System (ADS)

Real wedge interferometers of the Fizeau-type do not allow for fringes in case of a spectral broad band source -or in short: for white light fringes. Here, the use of a suitable frequency comb source will help to overcome this limitation on the one hand and on the other it offers the capability for enhanced phase sensitivity in high precision measurements of surface deviations. Frequency combs can be produced by passive filtering of the light emitted by a broad band source as a superlum-diode or a fs-laser. The frequency comb produced by a common fs-laser is extremely fine, i.e., the frequency difference of consecutive peaks is very small or the distance of consecutive pulses of the pulse train might be of the order of 1 m. Therefore, the coarse pulse train produced by passive filtering of a broad band source is better adapted to the needs of surface testing interferometers. White light fringes are either applied for the profiling of discontinuous surfaces or can serve as an indication for the correct choice of the subdivision of the inter order distance for multiple beam fringes. During the last decennium it became more and more clear that spatially incoherent sources provide better measuring accuracy in surface measurements due to the reduced influence of dust diffraction patterns. The advantage of laser illumination can nevertheless be maintained if the laser light is made spatially incoherent through moving scatterers in the light path. Here, we will discuss the application of spatially incoherent broad band light frequency filtered through a Fabry-Perot filter. The main applications are in the following fields: (1) surface profiling applications using two-beam Fizeau interferometers, (2) selection of single cavities out of a series of interlaced cavities, and (3) sensitivity enhancement for multi-beam interferometers for planeness or sphericity measurements. The emphasis of the presented work will be on the sensitivity enhancement provided by multiple beam interferometry in combination with frequency comb illumination. Through the use of a set of properly selected wavelengths the resulting interference pattern will become on the one hand more and more cosine-type with increasing enhancement factors and on the other hand it will be shown how the nonlinear relationship of the intensity distribution on the phase in the multiple beam interferometer can be overcome. Typical systematic errors show a periodicity with 4-times the fringe frequency of the interference pattern. By using the averaging of the measuring results of two measurements having a phase offset of ?/4 it is possible to reduce this error by at least one order of magnitude. The impact of the nonlinear intensity profile of multiple beam fringes in transmitted light can in addition be reduced through inverted intensity values in the common phase shifting equations. It will be shown that in this way repeatability values can be obtained of 1.2 A? peak to valley and 0.12 A? rms.

Schwider, J.

2010-04-01

410

Halomicrobium mukohataei gen. nov., comb. nov., and emended description of Halomicrobium mukohataei.  

PubMed

Haloarcula mukohataei, previously isolated from soils of salt flats in Argentina, was originally placed in the genus Haloarcula on the basis of 16S rRNA gene sequence comparison. However, its morphology and polar lipid composition differs from that of the other Haloarcula species. In addition, its phylogenetic distance from other Haloarcula species is rather large, and the 16S rDNA sequence does not contain many of the signature bases characteristic of the genus. Transfer of the species to a new genus was therefore recommended by the International Committee on Systematic Bacteriology Subcommittee on the taxonomy of Halobacteriaceae. A full description of the isolate, proposed as a member of a new genus, Halomicrobium, as Halomicrobium mukohataei comb. nov., is presented. The type strain is strain arg-2T (= JCM 9738T = DSM 12286T = ATCC 700874T = NCIMB 13541T). PMID:12361294

Oren, Aharon; Elevi, Rahel; Watanabe, Satoshi; Ihara, Kunio; Corcelli, Angela

2002-09-01

411

Self-assembly in solution of a reversible comb-shaped supramolecular polymer  

E-print Network

We report a single step synthesis of a polyisobutene with a bis-urea moiety in the middle of the chain. In low polarity solvents, this polymer self-assembles by hydrogen bonding to form a combshaped polymer with a central hydrogen bonded backbone and polyisobutene arms. The comb backbone can be reversibly broken, and consequently, its length can be tuned by changing the solvent, the concentration or the temperature. Moreover, we have proved that the bulkiness of the side-chains have a strong influence on both the self-assembly pattern and the length of the backbone. Finally, the density of arms can be reduced, by simply mixing with a low molar mass bis-urea.

Sandrine Pensec; Nicolas Nouvela; Audrey Guilleman; Costantino Creton; François Boué; Laurent Bouteiller

2010-05-28

412

Transmission characteristics of Mach-Zehnder interferometer comb filter based on thermal operation  

NASA Astrophysics Data System (ADS)

We propose and experimentally demonstrate switchable and tunable transmission characteristics of a Mach-Zehnder interferometer comb filter based on thermal operation. Its temperature characteristics are investigated to reveal a shift in the peak wavelength position from 0.003 to 0.004 nm/°C and a tunable range of wavelength spacing of 0.76-0.90 nm for maximum and minimum effective lengths, respectively. This configuration provides the unique advantages of an all-fiber structure, tunable wavelength spacing, switchable spectral peaks, independent tuning of the center wavelength and wavelength spacing of the spectral peaks, and low polarization sensitivity. It is relatively simple to fabricate and expected to have applications in temperature fiber optic sensors and multiwavelength fiber laser sources.

Islam, M. S.; Mohammad, A. B.

2014-10-01

413

Coherent population trapping in {sup 87}Rb atoms induced by the optical frequency comb excitation  

SciTech Connect

The excitation of room-temperature four-level {sup 87}Rb atoms by a train of ultrashort pulses is investigated theoretically in the conditions when the pulse repetition period is shorter than the characteristic atomic relaxation times. It is shown that coherent accumulation of excitation leads to coherent population trapping and electromagnetically induced transparency of the excitation pulses when the pulse repetition rate is a subharmonic of the ground-state hyperfine splitting. It is illustrated how the judicious choice for the frequency comb parameters can provide a means to effectively control the degree of coherence between the ground-state hyperfine levels for selective atomic groups, and even transfer the whole atomic distribution to the dark state with up to 95% efficiency.

Aumiler, D. [Institute of Physics, Bijenicka cesta 46, Zagreb, HR-10001 (Croatia)

2010-11-15

414

Large-Stroke Self-Aligned Vertical Comb Drive Actuators for Adaptive Optics Applications  

SciTech Connect

A high-stroke micro-actuator array was designed, modeled, fabricated and tested. Each pixel in the 4x4 array consists of a self-aligned vertical comb drive actuator. This micro-actuator array was designed to become the foundation of a micro-mirror array that will be used as a deformable mirror for adaptive optics applications. Analytical models combined with CoventorWare{reg_sign} simulations were used to design actuators that would move up to 10{micro}m in piston motion with 100V applied. Devices were fabricated according to this design and testing of these devices demonstrated an actuator displacement of 1.4{micro}m with 200V applied. Further investigation revealed that fabrication process inaccuracy led to significantly stiffer mechanical springs in the fabricated devices. The increased stiffness of the springs was shown to account for the reduced displacement of the actuators relative to the design.

Carr, E J; Olivier, S S; Solgaard, O

2005-10-27

415

High-speed, rate-scalable photonic-assisted digitizer equalization by frequency comb referencing.  

PubMed

A scalable analog-to-digital converter based on polychromatic sampling and optical-domain frequency referencing is described. The new architecture relies on low-distortion replication of an optical signal to spectrally distinct copies and subsequent polychromatic parametric sampling. Frequency comb referencing of parametric replication and sampling was used to convert processor distortions into quasi-stationary impairments and enable a practical equalization implementation. The operation of the new digitizer was demonstrated at 30 GS/s, achieving 6.5 effective number of bits in the first Nyquist zone. In contrast to conventional analog-to-digital converters, the new preprocessor sampling bandwidth is not restricted to the first Nyquist zone, and can operate in the second and third Nyquist zones beyond 40 GHz. PMID:25321503

Wiberg, A O J; Esman, D J; Temprana, E; Myslivets, E; Kuo, B P-P; Alic, N; Radic, S

2014-09-01

416

Broadband cavity-enhanced molecular spectra from Vernier filtering of a complete frequency comb.  

PubMed

We present a new approach to cavity enhanced-direct frequency comb spectroscopy where the full emission bandwidth of a titanium:sapphire laser is exploited, currently at gigahertz resolution. The technique is based on low-resolution Vernier filtering obtained with an appreciable actively stabilized mismatch between the cavity-free spectral range and the laser repetition rate, using a diffraction grating and a split-photodiode. Spectra covering 1300??cm?¹ (40 THz) are acquired in less than 100 ms, and a baseline noise of 1.7×10?? cm?¹ is reached with a cavity finesse of only 300, providing an absorption figure of merit M=6×10?¹¹ cm?¹·Hz(-1/2). PMID:25490647

Rutkowski, Lucile; Morville, Jérôme

2014-12-01

417

Comb-assisted subkilohertz linewidth quantum cascade laser for high-precision mid-infrared spectroscopy  

SciTech Connect

We report on the linewidth narrowing of a room-temperature mid-infrared quantum cascade laser by phase-locking to a difference-frequency-generated radiation referenced to an optical frequency comb synthesizer. A locking bandwidth of 250 kHz, with a residual rms phase-noise of 0.56 rad, has been achieved. The laser linewidth is narrowed by more than 2 orders of magnitude below 1 kHz, and its frequency is stabilized with an absolute traceability of 2 Multiplication-Sign 10{sup -12}. This source has allowed the measurement of the absolute frequency of a CO{sub 2} molecular transition with an uncertainty of about 1 kHz.

Galli, I.; Cappelli, F.; Bartalini, S.; Mazzotti, D.; Giusfredi, G.; Cancio, P.; De Natale, P. [CNR-INO-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI (Italy) [CNR-INO-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI (Italy); LENS-European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI (Italy); Siciliani de Cumis, M. [CNR-INO-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI (Italy)] [CNR-INO-Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, FI (Italy); Borri, S. [CNR-IFN-Istituto di Fotonica e Nanotecnologie, Via Amendola 173, 70126 Bari, BA (Italy)] [CNR-IFN-Istituto di Fotonica e Nanotecnologie, Via Amendola 173, 70126 Bari, BA (Italy); Montori, A. [LENS-European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI (Italy)] [LENS-European Laboratory for Non-Linear Spectroscopy, Via Carrara 1, 50019 Sesto Fiorentino, FI (Italy); Akikusa, N. [Development Bureau Laser Device R and D Group, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan)] [Development Bureau Laser Device R and D Group, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan); Yamanishi, M. [Central Research Laboratories, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan)] [Central Research Laboratories, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan)

2013-03-25

418

Reliable non-ambiguity range extension with dual-comb simultaneous operation in absolute distance measurements  

NASA Astrophysics Data System (ADS)

We report an absolute distance measurement scheme using two simultaneous optical frequency combs with different repetition rates for reliable non-ambiguity range extension. Since the non-ambiguity range extension is susceptible to distance drift during the repetition rate adjustment, pulse trains with two different repetition rates are coupled and directed simultaneously onto a target for coincident distance measurement. The simultaneous measurement avoids the process of adjusting the repetition rate and suppresses the influence of distance drift therein. The distances measured by the two repetition rates are distinguished by type II second harmonic generation. Target movement and atmospheric variation are made to imitate the distance drift, and experimental results show that the non-ambiguity range extension remains effective along the measurement.

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

2014-12-01

419

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

NASA Astrophysics Data System (ADS)

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

Galindo-Santos, J.; Velasco, A. V.; Corredera, P.

2015-01-01

420

A new Generation of Spectrometer Calibration Techniques based on Optical Frequency Combs  

E-print Network

Typical astronomical spectrographs have a resolution ranging between a few hundred to 200.000. Deconvolution and correlation techniques are being employed with a significance down to 1/1000 th of a pixel. HeAr and ThAr lamps are usually used for calibration in low and high resolution spectroscopy, respectively. Unfortunately, the emitted lines typically cover only a small fraction of the spectrometer's spectral range. Furthermore, their exact position depends strongly on environmental conditions. A problem is the strong intensity variation between different (intensity ratios {>300). In addition, the brightness of the lamps is insufficient to illuminate a spectrograph via an integrating sphere, which in turn is important to calibrate a long-slit spectrograph, as this is the only way to assure a uniform illumination of the spectrograph pupil. Laboratory precision laser spectroscopy has experienced a major advance with the development of optical frequency combs generated by pulsed femto-second lasers. These lasers emit a broad spectrum (several hundred nanometers in the visible and near infra-red) of equally-spaced "comb" lines with almost uniform intensity (intensity ratios typically laser establishes a precise ruler in frequency space that can be stabilized to the 10e-18 uncertainty level, reaching absolute frequency inaccuracies at the 10e-12 level per day when using the Global Positioning System's (GPS) time signal as the reference. The exploration of the merits of this new technology holds the promise for broad-band, highly accurate and reproducible calibration required for reliable operation of current and next generation astronomic spectrometers.

Piet O. Schmidt; Stefan Kimeswenger; Hans Ulrich Kaeufl

2007-05-05

421

Oil industry wastewater treatment with fouling resistant membranes containing amphiphilic comb copolymers.  

PubMed

The oil industry produces large volumes of wastewater, including oil well produced water brought to the surface during oil drilling, and refinery wastewater. These streams are difficult to treat due to large concentrations of oil. Ultrafiltration (UF) is very promising for their treatment to remove oil, but has been limited by economic obstacles due to severe membrane fouling. In a recent study, novel UF membranes incorporating the amphiphilic comb copolymer additive polyacrylonitrile-graft-poly(ethylene oxide), PAN-g-PEO, were found to exhibit complete resistance to irreversible fouling by several classes of organic foulants (J. Membr. Sci. 2007, 298, 136-146). The current work focuses on application of these novel UF membranes to the treatment of oily wastewater feed streams, employing three industrial samples of oil well produced water and refinery wastewater. UF membranes cast with 20 wt % PAN-g-PEO in PAN achieved removals of dispersed and free oils of over 96% based on chemical oxygen demand (COD) for produced water samples, comparable to a PAN UF commercial membrane control. For refinery wastewater treatment the COD removal values were substantially lower, between 41 and 44%, due to higher contents of dissolved organics. Comb copolymer modified membranes showed significantly better fouling resistance than controls, recovering fully their initial fluxes after a simulated backwash for each of the three wastewater samples tested. The results indicate that UF membranes incorporating PAN-g-PEO can be cleaned completely by physical methods alone, which should extend membrane lifetimes substantially and improve the process economics for treatment of oil-contaminated waters. PMID:19603666

Asatekin, Ayse; Mayes, Anne M

2009-06-15

422

Combinations of Earth orientation measurements: SPACE94, COMB94, and POLE94  

NASA Astrophysics Data System (ADS)

A Kalman filter has been used to combine independent measurements of the Earth's orientation taken by the space-geodetic observing techniques of lunar laser ranging, satellite laser ranging, very long baseline interferometry, and the Global Positioning System. Prior to their combination, the data series were adjusted to have the same bias and rate, the stated uncertainties of the measurements were adjusted, and data points considered to be outliers were deleted. The resulting combination, SPACE94, consists of smoothed, interpolated polar motion and UT1-UTC values spanning October 6.0, 1976, to January 27.0, 1995, at 1-day intervals. The Kalman filter was then used to combine the space-geodetic series comprising SPACE94 with two different, independent series of Earth orientation measurements taken by the technique of optical astrometry. Prior to their combination with SPACE94, the bias, rate and annual term of the optical astrometric series were corrected, the stated uncertainties of the measurements were adjusted, and data points considered to be outliers were deleted. The adjusted optical astrometric series were then combined with SPACE94 in two steps: (1) the Bureau International de l'Heure (BIH) optical astrometric series was combined with SPACE94 to form COMB94, a combined series of smoothed, interpolated polar motion and UT1-UTC values spanning January 20.0, 1962, to January 27.0, 1995, at 5-day intervals, and (2) the International Latitude Service (ILS) optical astrometric series was combined with COMB94 to form POLE94, a combined series of smoothed, interpolated polar motion values spanning January 20, 1900, to January 21, 1995, at 30.4375-day intervals.

Gross, Richard S.

1996-04-01

423

Combinations of Earth Orientation Measurements: SPACE94, COMB94, and POLE94  

NASA Technical Reports Server (NTRS)

A Kalman filter has been used to combine independent measurements of the Earth's orientation taken by the space-geodetic observing techniques of lunar laser ranging, satellite laser ranging, very long baseline interferometry, and the Global Positioning System. Prior to their combination, the data series were adjusted to have the same bias and rate, the stated uncertainties of the measurements were adjusted, and data points considered to be outliers were deleted. The resulting combination, SPACE94, consists of smoothed, interpolated polar motion and UT1-UTC values spanning October 6, 1976, to January 27, 1995, at 1-day intervals. The Kalman filter was then used to combine the space-geodetic series comprising SPACE94 with two different, independent series of Earth orientation measurements taken by the technique of optical astrometry. Prior to their combination with SPACE94, the bias, rate and annual term of the optical astrometric series were corrected, the stated uncertainties of the measurements were adjusted, and data points considered to be outliers were deleted. The adjusted optical astrometric series were then combined with SPACE94 in two steps: (1) the Bureau International de l'Heure (BIH) optical astrometric series was combined with SPACE94 to form COMB94, a combined series of smoothed, interpolated polar motion and UT1-UTC values spanning January 20, 1962, to January 27, 1995, at 5-day intervals, and (2) the International Latitude Service (ILS) optical astrometric series was combined with COMB94 to form POLE94, a combined series of smoothed, interpolated polar motion values spanning January 20, 1900, to January 21, 1995, at 30.4375-day intervals.

Gross, Richard S.

1996-01-01

424

RF-MEMS switching devices using vertical comb-drive actuation in the CMOS process  

NASA Astrophysics Data System (ADS)

Radio frequency micro-electro-mechanical system (RF-MEMS) switching devices using vertical comb-drive actuation toward low-voltage actuation, fast response are presented in this paper. The switching devices, which comprise comb-drive electrodes, are actuated entirely by the electrostatic forces applied not only for the down-state but also for the up-state. The cost-effective MEMS process compatible with the complementary metal oxide semiconductor (CMOS) process is presented in this paper as well. The fabrication process is composed by adapting the CMOS 0.18 µm back end of line (BEOL) process on 200 mm wafers. The MEMS process in the CMOS process enables the realization of passive devices integrated with active devices, which is effective for size and cost reduction. Two metal interconnection layers in the BEOL process are used for the MEMS process. Interconnection aluminum and inter-layer dielectric tetraethoxysilane (TEOS) are used as MEMS structural material and sacrificial material, respectively. The chemical mechanical polishing (CMP) process is implemented to planarize the sacrificial material surface. The structures were fabricated using a simple low-cost two-mask process. The characteristics of switching capacitors, C-V, RF performance, switching speed and continuous drive cycles are measured on the fabricated devices. The capacitance ratio for the down-state/up-state is Cdown/Cup = 5.4. The characteristics of switching speed response/actuation voltage in the down-state and up-state are 4.5 µs/5 V and 8.0 µs/5 V, respectively. The switching speed is stable up to 107 cycles in spite of the fact that the unipolar voltage speed is stable up to 107 cycles.

Naito, Y.; Nakamura, K.; Onishi, K.

2010-04-01

425

Inbreeding and parasite sex ratios.  

PubMed Central

The breeding system of parasitic protozoa affects the evolution of drug resistance and virulence, and is relevant to disease diagnosis and the development of chemo- and immunotherapy. A major group of protozoan parasites, the phylum Apicomplexa, that includes the aetiological agents of malaria, toxoplasmosis and coccidiosis, all have dimorphic sexual stages. The sex ratio (proportion of males produced by parasites) is predicted to depend upon the inbreeding rate, and it has been suggested that sex-ratio data offer a relatively cheap and easy method for indirectly estimating inbreeding rates. Here, we exploit a new theoretical machinery to show that there are generally valid relationships between f, Wright's coefficient of inbreeding, and sex ratio, z(*), the generality being with respect to population structure. To focus the discussion, we concentrate on malaria and show that the previously derived result, f = 1 - 2z(*), does not depend on the artificial assumptions about population structure that were previously made. Not only does this justify the use of sex ratio as an indirect measure of f, but also we argue that it may actually be preferable to measure f by measuring sex ratios, rather than by measuring departures from Hardy-Weinberg genotypic proportions both in malaria and parasites more generally. PMID:11934369

Nee, Sean; West, Stuart A; Read, Andrew F

2002-01-01

426

HIV and female sex workers.  

PubMed Central

In this review of published findings on human immunodeficiency virus (HIV) infection and risk factors among female sex workers, we summarize the results of seroprevalence studies in different countries and discuss the different patterns of transmission among such workers in various geographical regions. The highest rates of HIV infection occur in sub-Saharan Africa, where the widespread existence of sexually transmitted diseases may play an important role in sustaining transmission. In Europe and North America injecting drug use continues to be the major factor associated with HIV infection among female sex workers, while in Latin America and parts of Asia there is a more mixed pattern of heterosexual and parenteral transmission from injecting drug use. Reviewed also are studies of the risk factors associated with HIV infection among female sex workers, such as drug use, sexual behaviour, the presence of sexually transmitted diseases, and condom use; in addition, we comment on some studies of the clients of sex workers. Finally, we propose directions that future research in this area might take and discuss various interventions that need to be undertaken to reduce HIV transmission among female sex workers. PMID:8324860

Estébanez, P.; Fitch, K.; Nájera, R.

1993-01-01

427

Sex work: a comparative study.  

PubMed

Explanations of adult involvement in sex work typically adopt one of two approaches. One perspective highlights a variety of negative experiences in childhood and adolescence, including physical and sexual abuse, family instability, poverty, associations with "pimps" and other exploiters, homelessness, and drug use. An alternative account recognizes that some of these factors may be involved, but underscores the contribution of more immediate circumstances, such as current economic needs, human capital, and employment opportunities. Prior research offers a limited assessment of these contrasting claims: most studies have focused exclusively on people working in the sex industry and they have not assessed the independent effects of life course variables central to these two perspectives. We add to this literature with an analysis that drew on insights from life course and life-span development theories and considered the contributions of factors from childhood, adolescence, and adulthood. Our comparative approach examined predictors of employment in sex work relative to two other low-income service or care work occupations: food and beverage serving and barbering and hairstyling. Using data from a study of almost 600 workers from two cities, one in Canada and the other in the United States, we found that both immediate circumstances and negative experiences from early life are related to current sex work involvement: childhood poverty, abuse, and family instability were independently associated with adult sex work, as were limited education and employment experience, adult drug use, and marital status. PMID:24671729

McCarthy, Bill; Benoit, Cecilia; Jansson, Mikael

2014-10-01

428

Sex, Gender, Genetics, and Health  

PubMed Central

This article addresses 2 questions. First, to what extent are sex and gender incorporated into research on genetics and health? Second, how might social science understandings of sex and gender, and gender differences in health, become more integrated into scholarship in this area? We review articles on genetics and health published in selected peer-reviewed journals. Although sex is included frequently as a control or stratifying variable, few articles articulate a conceptual frame or methodological justification for conducting research in this way, and most are not motivated by sex or gender differences in health. Gender differences in health are persistent, unexplained, and shaped by multilevel social factors. Future scholarship on genetics and health needs to incorporate more systematic attention to sex and gender, gender as an environment, and the intertwining of social and biological variation over the life course. Such integration will advance understandings of gender differences in health, and may yield insight regarding the processes and circumstances that make genomic variation relevant for health and well-being. PMID:23927517

Yang, Yang Claire; Jenkins, Tania M.

2013-01-01

429

Coherent control and giant enhancement of multiphoton ionization and high-order-harmonic generation driven by intense frequency-comb laser fields: An ab initio theoretical investigation  

E-print Network

We present an ab initio theoretical investigation of the coherent control and significant enhancement of multiphoton ionization (MPI) and high-order-harmonic generation (HHG) of atoms and molecules by means of intense frequency-comb laser fields. We...

Chu, Shih-I; Zhao, Di; Li, Fu-li

2013-04-11

430

Sex-biased gene expression at homomorphic sex chromosomes in emus and its implication for sex chromosome evolution.  

PubMed

Sex chromosomes originate from autosomes. The accumulation of sexually antagonistic mutations on protosex chromosomes selects for a loss of recombination and sets in motion the evolutionary processes generating heteromorphic sex chromosomes. Recombination suppression and differentiation are generally viewed as the default path of sex chromosome evolution, and the occurrence of old, homomorphic sex chromosomes, such as those of ratite birds, has remained a mystery. Here, we analyze the genome and transcriptome of emu (Dromaius novaehollandiae) and confirm that most genes on the sex chromosome are shared between the Z and W. Surprisingly, however, levels of gene expression are generally sex-biased for all sex-linked genes relative to autosomes, including those in the pseudoautosomal region, and the male-bias increases after gonad formation. This expression bias suggests that the emu sex chromosomes have become masculinized, even in the absence of ZW differentiation. Thus, birds may have taken different evolutionary solutions to minimize the deleterious effects imposed by sexually antagonistic mutations: some lineages eliminate recombination along the protosex chromosomes to physically restrict sexually antagonistic alleles to one sex, whereas ratites evolved sex-biased expression to confine the product of a sexually antagonistic allele to the sex it benefits. This difference in conflict resolution may explain the preservation of recombining, homomorphic sex chromosomes in other lineages and illustrates the importance of sexually antagonistic mutations driving the evolution of sex chromosomes. PMID:23547111

Vicoso, Beatriz; Kaiser, Vera B; Bachtrog, Doris

2013-04-16

431

Sex chromosome polymorphism in guppies.  

PubMed

Sex chromosomes differ from autosomes by dissimilar gene content and, at a more advanced stage of their evolution, also in structure and size. This is driven by the divergence of the Y or W from their counterparts, X and Z, due to reduced recombination and the resulting degeneration as well as the accumulation of sex-specific and sexually antagonistic genes. A paradigmatic example for Y-chromosome evolution is found in guppies. In these fishes, conflicting data exist for a morphological and molecular differentiation of sex chromosomes. Using molecular probes and the previously established linkage map, we performed a cytogenetic analysis of sex chromosomes. We show that the Y chromosome has a very large pseudoautosomal region, which is followed by a heterochromatin block (HCY) separating the subtelomeric male-specific region from the rest of the chromosome. Interestingly, the size of the HCY is highly variable between individuals from different population. The largest HCY was found in one population of Poecilia wingei, making the Y almost double the size of the X and the largest chromosome of the complement. Comparative analysis revealed that the Y chromosomes of different guppy species are homologous and share the same structure and organization. The observed size differences are explained by an expansion of the HCY, which is due to increased amounts of repetitive DNA. In one population, we observed also a polymorphism of the X chromosome. We suggest that sex chromosome-linked color patterns and other sexually selected genes are important for maintaining the observed structural polymorphism of sex chromosomes. PMID:24676866

Nanda, Indrajit; Schories, Susanne; Tripathi, Namita; Dreyer, Christine; Haaf, Thomas; Schmid, Michael; Schartl, Manfred

2014-08-01

432

Design and fabrication of a high-aspect-ratio parylene-based comb-drive actuator for large displacements at a low driving force  

NASA Astrophysics Data System (ADS)

This paper presents a comb-drive actuator integrated with parylene-based flexible beams for large displacements at a low driving force. Single-crystal silicon and polysilicon are the traditional materials used for comb-drive actuators in the microeletromechanical systems industry. However, the larger Young's modulus limits the displacement at a low applied voltage. This study uses the parylene beams with the characteristic of a low modulus of the elastic comb-drive actuator as a compliant suspension to create a larger displacement (>50 µm) with smaller driving forces than that of silicon. High-aspect-ratio parylene beams can be fabricated through the deposition and removal of parylene in multiple stages on a silicon micro-trench. The proposed process uses a silicon-on-insulator wafer as the substrate to fabricate suspended silicon and parylene beams as rigid and compliant structures, respectively. The test devices of parylene- and silicon-based comb-drive actuators were fabricated with 100 pairs of comb fingers with gaps of 5 µm, and compliant beams of 15 µm in width, 2000 µm in span and 50 µm in thickness. When a driving voltage of 40 V dc was applied, the parylene-based comb-drive actuator generated a displacement of up to 55 µm, whereas the silicon-based comb-drive actuator generated a displacement of 2 µm. The parylene-based comb-drive actuator can generate about 27 times of displacement than that of silicon. This design is suitable for application in devices with large in-plane displacement and low switching speed.

Kuo, Wen-Cheng; Chen, Chen-Wei; Liu, Chih-Ming

2013-06-01

433

Factors causing sex differences in birds  

PubMed Central

In recent years, increasing evidence suggests that sex differences in the phenotype of all tissues is influenced by the inequality of effects of sex chromosome genes in the two sexes. In birds, genes on the Z chromosome are not well dosage compensated, so that most Z genes are expressed higher in ZZ male cells than in ZW female cells. The sex difference in expression of Z and W genes is likely to cause sex differences within cells, in addition to the sex differences caused by different levels of testicular and ovarian hormones. The sexual imbalance in cell physiology has implications for aviculture and novel developments in the poultry industry. PMID:24353746

Arnold, Arthur P.; Itoh, Yuichiro

2013-01-01

434

Factors causing sex differences in birds.  

PubMed

In recent years, increasing evidence suggests that sex differences in the phenotype of all tissues is influenced by the inequality of effects of sex chromosome genes in the two sexes. In birds, genes on the Z chromosome are not well dosage compensated, so that most Z genes are expressed higher in ZZ male cells than in ZW female cells. The sex difference in expression of Z and W genes is likely to cause sex differences within cells, in addition to the sex differences caused by different levels of testicular and ovarian hormones. The sexual imbalance in cell physiology has implications for aviculture and novel developments in the poultry industry. PMID:24353746

Arnold, Arthur P; Itoh, Yuichiro

2011-07-01

435

Elusive Sex Acts: Pleasure and Politics in Norwegian Sex Education  

ERIC Educational Resources Information Center

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…

Svendsen, Stine H. Bang

2012-01-01

436

Learning about Sex: Resource Guide for Sex Educators. Revised Edition  

ERIC Educational Resources Information Center

Whether you are someone new to the field of sex education, trying to start a library or resource center on adolescent sexual health, or an old pro, this guide should give you a basic orientation to what's available to support your work. These resources are important to advancing positive attitudes toward adolescent sexual health and the author…

Huberman, Barbara

2011-01-01

437

Courses for Teachers on Sex Differences and Sex Typing.  

ERIC Educational Resources Information Center

This article describes initiatives to remedy sex discrimination and stereotyping among teachers undertaken by the Didsbury School of Education (Manchester, England). Both preservice teacher education courses and an action research project aimed at inservice teachers are discussed. Concern about female underachievement in mathematics and science is…

Whyte, Judith

1983-01-01

438

Sex offenders and sex crime recidivism: investigating the role of sentence length and time served.  

PubMed

The relationship between criminal justice sanctions and sex crime recidivism remains largely unexplored. Therefore, using a sample of 8,461 previously incarcerated male sex offenders from 13 states in the United States, we focus on the sentence meted out for the sex crime conviction and the amount of time sex offenders served as a result of their conviction. Sex offenders were grouped into four categories: rapists, sexual assaulters, child molesters, and all sex offenders combined. Recidivism was operationalized as rearrest and reconviction. Findings suggest how recidivism is operationalized matters. When recidivism is measured as rearrest for another sex offense, sentence length and time served are unrelated to sex crime recidivism. On the other hand, when recidivism is operationalized as reconviction for another sex offense, sentence length is positively related to recidivism for rapists, sexual assaulters, child molesters, and all sex offenders combined, while time served is negatively related to recidivism for child molesters and all sex offenders combined. PMID:24114424

Budd, Kristen; Desmond, Scott A

2014-12-01

439

Conflict over condition-dependent sex allocation can lead to mixed sex-determination systems.  

PubMed

Theory suggests that genetic conflicts drive turnovers between sex-determining mechanisms, yet these studies only apply to cases where sex allocation is independent of environment or condition. Here, we model parent-offspring conflict in the presence of condition-dependent sex allocation, where the environment has sex-specific fitness consequences. Additionally, one sex is assumed to be more costly to produce than the other, which leads offspring to favor a sex ratio less biased toward the cheaper sex in comparison to the sex ratio favored by mothers. The scope for parent-offspring conflict depends on the relative frequency of both environments: when one environment is less common than the other, parent-offspring conflict can be reduced or even entirely absent, despite a biased population sex ratio. The model shows that conflict-driven invasions of condition-independent sex factors (e.g., sex chromosomes) result either in the loss of condition-dependent sex allocation, or, interestingly, lead to stable mixtures of condition-dependent and condition-independent sex factors. The latter outcome corresponds to empirical observations in which sex chromosomes are present in organisms with environment-dependent sex determination. Finally, conflict can also favor errors in environmental perception, potentially resulting in the loss of condition-dependent sex allocation without genetic changes to sex-determining loci. PMID:25180669

Kuijper, Bram; Pen, Ido

2014-11-01

440

Conflict over condition-dependent sex allocation can lead to mixed sex-determination systems  

PubMed Central

Theory suggests that genetic conflicts drive turnovers between sex-determining mechanisms, yet these studies only apply to cases where sex allocation is independent of environment or condition. Here, we model parent–offspring conflict in the presence of condition-dependent sex allocation, where the environment has sex-specific fitness consequences. Additionally, one sex is assumed to be more costly to produce than the other, which leads offspring to favor a sex ratio less biased toward the cheaper sex in comparison to the sex ratio favored by mothers. The scope for parent–offspring conflict depends on the relative frequency of both environments: when one environment is less common than the other, parent–offspring conflict can be reduced or even entirely absent, despite a biased population sex ratio. The model shows that conflict-driven invasions of condition-independent sex factors (e.g., sex chromosomes) result either in the loss of condition-dependent sex allocation, or, interestingly, lead to stable mixtures of condition-dependent and condition-independent sex factors. The latter outcome corresponds to empirical observations in which sex chromosomes are present in organisms with environment-dependent sex determination. Finally, conflict can also favor errors in environmental perception, potentially resulting in the loss of condition-dependent sex allocation without genetic changes to sex-determining loci. PMID:25180669

Kuijper, Bram; Pen, Ido

2014-01-01

441

Generation of broadband optical frequency comb with rectangular envelope using cascaded intensity and dual-parallel modulators  

NASA Astrophysics Data System (ADS)

A novel approach using two cascaded intensity modulators and one single dual-parallel modulator to generate an optical frequency comb (OFC) is proposed and experimentally demonstrated. One broadband OFC with rectangular envelope can be achieved easily by adjusting the power of the microwave signals and the direct current bias applied to the modulators. The scheme is a relatively simple and low-power consumption solution for OFC generation, where specially tailored waveforms and high-power microwave signals are not used. In the experiment, 20 comb lines within 0.6 dB spectral power variation are obtained at 10 GHz microwave frequency. The experimental results agree well with the theoretical calculation.

Zhou, Xin; Zheng, Xiaoping; Wen, He; Zhang, Hanyi; Zhou, Bingkun

2014-02-01

442

Full characterization of a highly multimode entangled state embedded in an optical frequency comb using pulse shaping  

NASA Astrophysics Data System (ADS)

We present a detailed analysis of the multimode quantum state embedded in an optical frequency comb generated by a synchronously pumped optical parametric oscillator (SPOPO) [J. Roslund, R. Medeiros de Araújo, S. Jiang, C. Fabre, and N. Treps, Nat. Photon. 8, 109 (2014), 10.1038/nphoton.2013.340]. The full covariance matrix of the state is obtained with homodyne detection where the local oscillator is spectrally controlled with pulse-shaping techniques. The resulting matrix reveals genuine multipartite entanglement. Additionally, the beam is comprised of several independent eigenmodes that correspond to specific pulse shapes. The experimental data is confirmed with numerical simulations. Finally, the potential to create continuous-variable cluster states from the quantum comb is analyzed. Multiple cluster states are shown to be simultaneously embedded in the SPOPO state, and these states can be revealed by a suitable basis change applied to the measured covariance matrix.

Medeiros de Araújo, R.; Roslund, J.; Cai, Y.; Ferrini, G.; Fabre, C.; Treps, N.

2014-05-01

443

Single Passband, Discretely Tunable, Photonic Microwave Bandpass Filter Based on Highly Birefringent Fiber-Based Comb Filter  

NASA Astrophysics Data System (ADS)

By experiment, we demonstrate a photonic microwave finite impulse response (FIR) filter scheme that exhibits both the features of flexible frequency tuning and single passband. The proposed filter is constructed by the combined use of a broadband Gaussian-shaped supercontinuum (SC) and a wavelength spacing tunable, highly birefringent (Hi-Bi) fiber-based comb filter. By incorporating a three-segment, Hi-Bi fiber-based, Lyot-type, comb filter into a spectrum slicing-based photonic microwave FIR filter scheme, we achieve both novel features of single passband and passband RF frequency tuning at the same time. It is shown that the discrete tuning of passband RF frequency can be obtained simply by rotating beam polarization. Our experimental demonstration shows a flexible passband RF frequency tuning over a range of 7.3 GHz.

Ryu, Uh-Chan; Chang, You Min; Lee, Ju Han

2008-10-01

444

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

PubMed

We present a femtosecond optical parametric oscillator (OPO) containing two magnesium-doped periodically poled lithium niobate crystals in a singly resonant ring cavity, pumped by two mode-locked Yb-fiber lasers. As such, the OPO generates two idler combs (up to 220 mW), covering a wavelength range from 2.7 to 4.2 ?m, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyning signal between the two idler beams a full broadband spectrum of a molecular gas can be observed over 250??cm(-1) within 70 ?s with a spectral resolution of 15 GHz. The absorption and dispersion spectra of acetylene and methane have been measured around 3000??cm(-1), indicating that this OPO represents an ideal broadband mid-infrared source for fast chemical sensing. PMID:24876030

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

2014-06-01

445

Children's occupational sex-typing  

Microsoft Academic Search

Preschool and elmentary school children responded to questions measuring sex-typing of attribution (who would like this job), service preference (who the child would choose to do this job), and personal job choice (would the child like to do this job) dimensions for each of nine jobs, and stated a free-choice job preference. A subsample completed a cognitive classification measure. With

Leslie S. Tremaine; Candace Garrett Schau; Judith Wilde Busch

1982-01-01

446

Helping parents with sex education.  

PubMed

Health visitors, school nurses and other community nurses are sometimes asked for advice by parents and carers on the emerging sexuality of their children. Parents often lack knowledge about sexual development and are confused about whether to talk to their children about sex. They may have been brought up in a family where sex was not mentioned. They are worried that they do not have the skills or the knowledge to help their children. They do not know whether to leave it all to the school or not allow their children to have any information. All the evidence shows that children who have had their questions answered and who know about sex and relationships start sexual activity later, use contraception more reliably and are less likely to cause or have an unwanted pregnancy. Sex education should be part of the ordinary information and moral guidance that parents normally give and should start as early as possible. The type of advice to give to parents and carers is split into age ranges that they might find helpful. Examples of language and the level of information required are given. A list of resources for further guidance is included. PMID:21678785

Wakley, Gill

2011-01-01

447

The arrangement between the sexes  

Microsoft Academic Search

.In modern industrial society, as apparently in all others, sex is at the base of a fundamental code in accordance with which social interactions and social structures are built up, a code which also establishes the conceptions individu. als have concerning their fundamental human nature. This is an oft stated proposition, but until recently its awesomely ramified significance escaped us.

Erving Goffman

1977-01-01

448

Sex Education in Professional Schools  

ERIC Educational Resources Information Center

Accompanying the changes in social attitudes toward sex and the discussion of controversial sexual issues is an increased public demand for sexual information and services, which the professional community is expected to supply. Discusses the professional's credentials and qualifications in counseling or dispensing information to those with sexual…

Maddock, James W.

1976-01-01

449

Sex Difference in Chimpanzee Handedness  

Microsoft Academic Search

Chimpanzees at Mahale, Tanzania, show strong individual hand preferences when they use biman- ual actions in processing the fruit of Saba florida and Citrus lemon. The direction of hand preference differs between the sexes: most males are left-handed, whereas most females are right-handed. Monkeys and apes are considered to lack \\

Richard W. Byrne

2004-01-01

450

Sex chromosomes and their abnormalities  

E-print Network

to the age of the mother #12;Jacobs syndrome XYY Apparently normal phenotype with possibly increased height is indicated in such patients #12;Sex chromosome anuploidies #12;Klinefelter Syndrome XXY Underdeveloped 2 Barr bodies 1/1000 female births #12;Turner Syndrome XO Missing X chromosome Sexually

Dellaire, Graham

451

Title IX and Sex Discrimination.  

ERIC Educational Resources Information Center

Title IX of the Education Amendments of 1972 protects people from discrimination based on sex in education programs or activities that receive Federal financial assistance. This brochure outlines the responsibilities of education programs and activities covered by Title IX, the responsibilities of the Office for Civil Rights (OCR) in enforcing…

Office for Civil Rights (ED), Washington, DC.

452

Sex Differences in Problem Solving.  

ERIC Educational Resources Information Center

Nine experiments were performed to verify and extend studies on sex differences in problem solving conducted in the 1950s by Sweeney, Carey, Milton, Nakamura, and Berry. A 20-item problem set was administered to over 1,000 college students. Results indicated a male advantage, averaging 35 percent, virtually identical with 1950s results. (Author/BS)

Johnson, Edward S.

1984-01-01

453

Zebrafish sex: a complicated affair  

PubMed Central

In this review, we provide a detailed overview of studies on the elusive sex determination (SD) and gonad differentiation mechanisms of zebrafish (Danio rerio). We show that the data obtained from most studies are compatible with polygenic sex determination (PSD), where the decision is made by the allelic combinations of several loci. These loci are typically dispersed throughout the genome, but in some teleost species a few of them might be located on a preferential pair of (sex) chromosomes. The PSD system has a much higher level of variation of SD genotypes both at the level of gametes and the sexual genotype of individuals, than that of the chromosomal sex determination systems. The early sexual development of zebrafish males is a complicated process, as they first develop a ‘juvenile ovary’, that later undergoes a transformation to give way to a testis. To date, three major developmental pathways were shown to be involved with gonad differentiation through the modulation of programmed cell death. In our opinion, there are more pathways participating in the regulation of zebrafish gonad differentiation/transformation. Introduction of additional powerful large-scale genomic approaches into the analysis of zebrafish reproduction will result in further deepening of our knowledge as well as identification of additional pathways and genes associated with these processes in the near future. PMID:24148942

Liew, Woei Chang

2014-01-01

454

Sex, Lies and Video Games  

ERIC Educational Resources Information Center

Sex and violence in video games is a social issue that confronts us all, especially as many commercial games are now being introduced for game-based learning in schools, and as such this paper polls teenage players about the rules their parents and teachers may or may not have, and surveys the gaming community, ie, game developers to parents, to…

Kearney, Paul; Pivec, Maja

2007-01-01

455

Sex differences in human jealousy  

Microsoft Academic Search

Previous investigators have confirmed the evolutionary hypothesis that the sexes differ in their responses to sexual vs. emotional infidelity and have taken their results as suggesting the existence of a mechanism that regulates the perceptions of threat, the emotional responses, and the physiological reactions that constitute jealousy. This notion implies that these three categories of response should occur systematically in

Robert H Pietrzak; James D Laird; David A Stevens; Nicholas S Thompson

2002-01-01

456

Grism-based pulse shaper for line-by-line control of more than 600 optical frequency comb lines.  

PubMed

We construct a line-by-line pulse shaper using a grism (grating plus prism) dispersive element, which provides constant angular dispersion over 13.4 THz centered at ~311 THz (965 nm). When combined with a dual-mask liquid crystal modulator, this grism-based shaper is capable of line-by-line amplitude and phase control of over 600 modes of a 21 GHz stabilized optical frequency comb. PMID:20890354

Kirchner, M S; Diddams, S A

2010-10-01

457

Multi-heterodyne molecular absorption spectrum detection of H13C14N based on dual frequency combs  

NASA Astrophysics Data System (ADS)

In order to acquire high-resolution molecular absorption spectrum, a measurement system consisting of two Erbium-doped fiber optical frequency combs based on multi-heterodyne detection method is established. Preliminary result shows that the specific line in the RF spectrum corresponding to 6452.59 cm-1 in the optical region, where there is an error of 0.14 cm-1 compared with the simulation result. And the further improvement of this system will be discussed in the end.

Yang, Honglei; Wei, Haoyun; Li, Yan

2014-11-01

458

Optical frequency comb generation based on electro-optical modulation with high-order harmonic of a sine RF signal  

NASA Astrophysics Data System (ADS)

By using cascaded intensity and phase modulators, optical frequency comb (OFC) is generated. In the OFC generation scheme, high-order harmonic of a RF signal is used for driving intensity modulator (IM) or phase modulator (PM). Experimental and theoretical results indicate when IM is driven by high-order harmonic, lower RF driving power for PM is required to generate an OFC with the best flatness.

Wei, Renjie; Yan, JuanJuan; Peng, Yichao; Yao, Xiayuan; Bai, Ming; Zheng, Zheng

2013-03-01

459

How Will Cancer Affect My Sex Life?  

MedlinePLUS

... for all this? How will cancer affect my sex life? Sexual feelings and attitudes vary greatly among ... you were comfortable with and enjoyed a healthy sex life before starting treatment, chances are you will ...

460

Gambling, Sex, and…Parkinson's Disease?  

MedlinePLUS

... and, in people with Parkinson's, most typically involve sex, gambling and abuse of anti-parkinsonian medications. Pathological ... clear sign of dysfunction in the nervous system), sex, gambling and shopping are common actions in everyday ...

461

Theoretical study of collinear optical frequency comb generation under multi-wave, transient stimulated Raman scattering in crystals  

NASA Astrophysics Data System (ADS)

Using mathematical modelling we have studied the conditions of low-threshold collinear optical frequency comb generation under transient (picosecond) stimulated Raman scattering (SRS) and parametric four-wave coupling of SRS components in crystals. It is shown that Raman-parametric generation of an octave-spanning optical frequency comb occurs most effectively under intermediate, transient SRS at a pump pulse duration exceeding the dephasing time by five-to-twenty times. We have found the optimal values of not only the laser pump pulse duration, but also of the Raman crystal lengths corresponding to highly efficient generation of an optical frequency comb from the second anti-Stokes to the fourth Stokes Raman components. For the KGd(WO4)2 (high dispersion) and Ba(NO3)2 (low dispersion) crystals pumped at a wavelength of 1.064 ?m and a pulse duration five or more times greater than the dephasing time, the optimum length of the crystal was 0.3 and 0.6 cm, respectively, which is consistent with the condition of the most effective Stokes – anti-Stokes coupling ?kL ? 15, where ?k is the wave detuning from phase matching of Stokes – anti-Stokes coupling, determined by the refractive index dispersion of the SRS medium.

Smetanin, S. N.

2014-11-01

462

Cavity-enhanced optical frequency comb spectroscopy in the mid-infrared application to trace detection of hydrogen peroxide  

NASA Astrophysics Data System (ADS)

We demonstrate the first cavity-enhanced optical frequency comb spectroscopy in the mid-infrared wavelength region and report the sensitive real-time trace detection of hydrogen peroxide in the presence of a large amount of water. The experimental apparatus is based on a mid-infrared optical parametric oscillator synchronously pumped by a high-power Yb:fiber laser, a high-finesse broadband cavity, and a fast-scanning Fourier transform spectrometer with autobalancing detection. The comb spectrum with a bandwidth of 200 nm centered around 3.76 ?m is simultaneously coupled to the cavity and both degrees of freedom of the comb, i.e. the repetition rate and carrier envelope offset frequency, are locked to the cavity to ensure stable transmission. The autobalancing detection scheme reduces the intensity noise by a factor of 300, and a sensitivity of 5.4×10-9 cm-1 Hz-1/2 with a resolution of 800 MHz is achieved (corresponding to 6.9×10-11 cm-1 Hz-1/2 per spectral element for 6000 resolved elements). This yields a noise equivalent detection limit for hydrogen peroxide of 8 parts-per-billion (ppb); in the presence of 2.8 % of water the detection limit is 130 ppb. Spectra of acetylene, methane, and nitrous oxide at atmospheric pressure are also presented, and a line-shape model is developed to simulate the experimental data.

Foltynowicz, A.; Mas?owski, P.; Fleisher, A. J.; Bjork, B. J.; Ye, J.

2013-02-01

463

Sex-role imitation in children: Effects of sex of child, sex of model, and sex-role appropriateness of modeled behavior  

Microsoft Academic Search

The qualifying influence of the sex-role appropriateness of observed behavior on children's same-sex imitation was investigated. In each of two studies employing a 2×2×2 design, girls and boys observed a live male or female model display appropriate (to the child's sex) or inappropriate behavior. Results that were consistent in both studies indicated an interaction between sex of child and appropriateness.

Pamela A. Raskin; Allen C. Israel

1981-01-01

464

Adoption by Same-Sex Couples  

Microsoft Academic Search

The current study investigated the relationship between sex-role beliefs and attitudes toward same-sex couple adoptions as suggested by Feminist and Queer theory. A mailed questionnaire was used to collect data from a purposive sample of adoption workers and social work students. The questionnaire included an abbreviated version of the Sex-Role Egalitarianism Scale and the newly created Attitudes Toward Same-Sex Couples

Christina A. Spivey

2006-01-01

465

Sex determination: the power of DMRT1.  

PubMed

DMRT1, a mammalian gene related to sex-determining genes in flies and nematodes, is located in a region of the human genome that is important for sex development. This suggests that a common thread might run through the evolution of sex-determining mechanisms from worms to humans. New data show that DMRT1 can cause sex reversal in chickens, adding support to this hypothesis. PMID:19819582

Koopman, Peter

2009-11-01

466

Heritable Variation for Sex Ratio Under Environmental Sex Determination in the Common Snapping Turtle (Chelydra serpentina)  

Microsoft Academic Search

The magnitude of quantitative genetic variation for primary sex ratio was measured in families extracted from a natural population of the common snapping turtle (Chelydra serpentina), which possesses temperature-dependent sex determination (TSD). Eggs were incubated at three tempera- tures that produced mixed sex ratios. This experimental design provided estimates of the heritability of sex ratio in multiple environments and a

Fredric J. Janzen

467

Observational learning in children: Effects of sex of model and subject's sex role behavior  

Microsoft Academic Search

Studied the relationship between children's sex role behavior and children's acquisition of behaviors exhibited by same- and opposite-sex adult models. 96 elementary school children of both sexes were classified as either masculine or feminine on the basis of their scores on a projective test of sex role behavior. They then watched a short film depicting the behavior of an adult

David G. Perry; Louise C. Perry

1975-01-01

468

The Relationship of Moral Reasoning to Sex Guilt and Sex Experience in College Couples.  

ERIC Educational Resources Information Center

Seventy-six college couples were interviewed with Kohlberg's moral dilemmas interview, given the Mosher Sex Guilt scale and took a sex experience inventory. Men, women, and couples who were at the law and order stage of moral reasoning were higher on sex guilt than those at other levels of morality. Male sex experience was associated with morality…

Cross, Herbert; D'Augelli, Judith F.

469

Facultative Sex Allocation and Sex-Specific Offspring Survival in Barrow's Goldeneyes  

E-print Network

Facultative Sex Allocation and Sex-Specific Offspring Survival in Barrow's Goldeneyes Kim Jaatinen Final acceptance: November 22, 2012 (J. Wright) doi: 10.1111/eth.12048 Abstract Sex allocation theory predicts that females should bias their reproductive investment towards the sex generating the greatest

470

SEX-LINKAGE AS A FACTOR IN THE INHERITANCE OF SEX DIFFERENCES  

E-print Network

SEX-LINKAGE AS A FACTOR IN THE INHERITANCE OF SEX DIFFERENCES FOR BODY WEIGHT IN TWO STRAINS Production Department, Ministry of Agriculture, Cairo (Egypt) SUMMARY The interactions « sex X Sire families » and a sex x dam within Sire families » in two strains of chickens, Dokki-4 and White Plymouth Rock, were

Paris-Sud XI, Université de

471

Sex as aSex as a Threshold TraitThreshold Trait  

E-print Network

1 Sex as aSex as a Threshold TraitThreshold Trait Overturning traditional paradigms on evolution and modes of sex determination in reptiles Arthur GeorgesArthur Georges Institute for Applied EcologyInstitute for Applied Ecology University of CanberraUniversity of Canberra We all agree that sex is a fundamental

Canberra, University of

472

Do humans adjust offspring sex according to the local operational sex ratio?  

E-print Network

Do humans adjust offspring sex according to the local operational sex ratio? Samuli Helle, 1 Pekka-Zürich), Zürich, Switzerland ABSTRACT Question: Do humans overproduce the rarer sex in response to skews in the local operational sex ratio (OSR)? And how should one define the OSR in humans? Hypothesis: We predicted

Helle, Samuli

473

The species, sex, and stage specificity of a Caenorhabditis sex pheromone  

E-print Network

The species, sex, and stage specificity of a Caenorhabditis sex pheromone J. R. Chasnov*, W. K. So chemotaxis assays, we demonstrate that females secrete a potent sex pheromone that attracts males from a distance, whereas hermaphrodites do not. The female sex pheromone is not species-specific, with males

Chasnov, Jeffrey R.

474

Sex Determination in Flies, Fruitflies and Butterflies  

Microsoft Academic Search

Sex determination mechanisms, differing in their modality, are widely represented in all the various animal taxa, even at the intraspecific level. Within the highly diversified Class Insecta, Drosophila has been used to unravel the mechanistic molecular and genetic interactions that are involved in sex determination. Indeed, the molecularly characterized genes of the Drosophila sex determination hierarchy X:A> Sxl> tra> dsxhave

G. Saccone; A. Pane; L. C. Polito

2002-01-01

475

L340 Biological Basis of Sex Differences  

E-print Network

differences. 5. Be able to define "sex" and "gender". 6. Evaluate arguments in the "nature-nurture" debate. 7 11/15 Human sex differences II. Nature vs. Nurture Th 11/17 Video: "Sex: Unknown" Tu 11/22 Topic of analysis are and their importance in evaluating scientific hypotheses. 4. Know how natural and sexual

Indiana University

476

SEX EDUCATION IN LEBANON AND FRANCE  

E-print Network

SEX EDUCATION IN LEBANON AND FRANCE Assaad Yammine1 , Iman Khalil1 and Pierre Clément2 1 Faculté de on safer sex as an attitude that can reduce the spread of AIDS, and to consider that the teaching of STIs and cultural context. Keywords: Sex education, Multiculturality, religion, conceptions, teachers 1 ­ Context

Boyer, Edmond

477

Sex determination: insights from the chicken  

E-print Network

genes have recently emerged. The Z-linked gene, DMRT1, supports the Z-dosage model of avian sex in gonadal sex dif- ferentiation. However, several genes shown to be critical for mammalian sex determination determination. Two novel W-linked genes, ASW and FET1, represent candidate female determinants. BioEssays 26

Meyers, Ron

478

The Promise of Single-Sex Classes  

ERIC Educational Resources Information Center

Despite the enthusiasm and the absence of definitive research on the pros and cons of single-sex classes, a 2011 article in Science, titled "The Pseudoscience of Single-Sex Schooling," by a new organization called American Council for CoEducational Schooling (ACCES) came out with the astonishing conclusion that single-sex education is ineffective…

Stotsky, Sandra

2012-01-01

479

77 FR 73558 - 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. The proposed rule, if finalized, would permit CSOSA to verify addresses of sex offenders by conducting home visits on...

2012-12-11

480

Sex Roles and Fertility in College Women.  

ERIC Educational Resources Information Center

The relationship of sex role acceptance to actual and desired fertility was assessed in a sample of female college students and women's organization members. Multiple regression analysis indicated that behavioral measures of sex role acceptance accounted for more variance in predicting desired fertility than did the Bem Sex Role Inventory.…

Falbo, Toni; And Others

1978-01-01

481

Genetics of sex determination in tilapiine species.  

PubMed

We identified DNA markers linked to sex determining genes in six closely related species of tilapiine fishes. The mode of sex determination differed among species. In Oreochromis karongae and Tilapia mariae the sex-determining locus is on linkage group (LG) 3 and the female is heterogametic (WZ-ZZ system). In O. niloticus and T. zillii the sex-determining locus is on LG1 and the male is heterogametic (XX-XY system). A more complex pattern was observed in O. aureus and O. mossambicus, in which markers on both LG1 and LG3 were associated with sex. We found evidence for sex-linked lethal effects on LG1, as well as interactions between loci in the two linkage groups. Comparison of genetic and physical maps demonstrated a broad region of recombination suppression harboring the sex-determining locus on LG3. Sex-specific recombination suppression was found in the female heterogametic sex. Sequence analysis showed the accumulation of repetitive elements in this region. Phylogenetic analysis suggests that at least two transitions in the mode of sex determination have occurred in this clade. This variation in sex determination mechanisms among closely related species makes tilapias an excellent model system for studying the evolution of sex chromosomes in vertebrates. PMID:18418034

Cnaani, A; Lee, B-Y; Zilberman, N; Ozouf-Costaz, C; Hulata, G; Ron, M; D'Hont, A; Baroiller, J-F; D'Cotta, H; Penman, D J; Tomasino, E; Coutanceau, J-P; Pepey, E; Shirak, A; Kocher, T D

2008-01-01

482

Evolution of sex chromosomes in Sauropsida  

Microsoft Academic Search

Synopsis Reptiles (sauropsids) represent the sister group to mammals, and the basal members of Reptilia may provide a good model for the condition of the common ancestor of both groups. Sex-determining mechanisms (SDM) and organizations of sex chromosomes among genotypically sex-determining (GSD) species vary widely across reptiles. Birds and snakes, for example, are entirely GSD whereas other reptiles, like all

Christopher L. Organ; Daniel E. Janes

2008-01-01

483

Denial and minimization among sex offenders  

Microsoft Academic Search

Defensiveness in sex offenders (DISO), although a very common phenomenon, is poorly understood by clinicians. Three explanatory models of DISO are explored. Thepathogenic model postulates from a psychodynamic perspective massive repression and denial are operative in the service of ego functions. Thecriminogenic model associates deception with the antisocial characteristics of sex offenders. Theadaptational model assumes that the sex offender is

Richard Rogers; Rob Dickey

1991-01-01

484

Comb-push Ultrasound Shear Elastography (CUSE) with Various Ultrasound Push Beams  

PubMed Central

Comb-push Ultrasound Shear Elastography (CUSE) has recently been shown to be a fast and accurate two-dimensional (2D) elasticity imaging technique that can provide a full field-of- view (FOV) shear wave speed map with only one rapid data acquisition. The initial version of CUSE was termed U-CUSE because unfocused ultrasound push beams were used. In this paper, we present two new versions of CUSE – Focused CUSE (F-CUSE) and Marching CUSE (M-CUSE), which use focused ultrasound push beams to improve acoustic radiation force penetration and produce stronger shear waves in deep tissues (e.g. kidney and liver). F-CUSE divides transducer elements into several subgroups which transmit multiple focused ultrasound beams simultaneously. M-CUSE uses more elements for each focused push beam and laterally marches the push beams. Both F-CUSE and M-CUSE can generate comb-shaped shear wave fields that have shear wave motion at each imaging pixel location so that a full FOV 2D shear wave speed map can be reconstructed with only one data acquisition. Homogeneous phantom experiments showed that U-CUSE, F-CUSE and M-CUSE can all produce smooth shear wave speed maps with accurate shear wave speed estimates. An inclusion phantom experiment showed that all CUSE methods could provide good contrast between the inclusion and background with sharp boundaries while F-CUSE and M-CUSE require shorter push durations to achieve shear wave speed maps with comparable SNR to U-CUSE. A more challenging inclusion phantom experiment with a very stiff and deep inclusion shows that better shear wave penetration could be gained by using F-CUSE and M-CUSE. Finally, a shallow inclusion experiment showed that good preservations of inclusion shapes could be achieved by both U-CUSE and F-CUSE in the near field. Safety measurements showed that all safety parameters are below FDA regulatory limits for all CUSE methods. These promising results suggest that, using various push beams, CUSE is capable of reconstructing a 2D full FOV shear elasticity map using only one push-detection data acquisition in a wide range of depths for soft tissue elasticity imaging. PMID:23591479

Song, Pengfei; Urban, Matthew W.; Manduca, Armando; Zhao, Heng; Greenleaf, James F.; Chen, Shigao

2013-01-01

485