Modal fields calculation using the finite difference beam propagation method

A method is described to construct modal fields for an arbitrary one- or two-dimensional refractive index structure. An arbitrary starting field is propagated along a complex axis using the slowly varying envelope approximation (SVEA). By choosing suitable values for the step-size, one mode is maximally increased in amplitude on propagating, until convergence has been obtained. For the calculation of the next mode, the mode just found is filtered out, and the procedure starts again. The method is tested for one-dimensional refractive index structures, both for nonabsorbing and for absorbing structures, and is shown to give fast convergenc

Ectoproct and entoproct type material: Reexamination of species from New England and Bermuda named by A. E. Verrill, J. W. Dawson and E. Desor

A. E. Verrill, J. W. Dawson, and E. Desor named 23 species of North American east coast ectoprocts and entoprocts prior to 1902. Chiefly from lack of illustration, the majority of these have been misunderstood in the literature. We have found material leading to a better understanding of 15 of these species in collections of the Peabody Museum of Natural History, Yale University, the U.S. National Museum, and the American Museum of Natural History. The following ectoproct species are described (original names): Amathia goodei Verrill, Bugula cucullata Verrill, Bugula decorata Verrill, Bugula flexilis Verrill, Bugula (Caulibugula) armata Verrill, Bugulella fragilis Verrill, Cellularia turrita Desor, Discopora nitida Verrill, Escharina porosa Verrill, Gemellaria willisii Dawson, Hippoporina verrilli Maturo and Schopf, Hippothoa expansa Dawson, Lepralia americana Verrill, Lepralia plana Dawson, Porellina stellata Verrill. One entoproct, Barentsia timida Verrill, is described. The coefficient of variation was determined for standard dimensional features. Data collected support Cheetham\u27s statistical verification that the most useful dimensional features for taxonomic purposes are ovicell length and width, zooid length, and primary orifice length and width. Length of adventitous avicularia and zooid width are the most variable of the traits measured, particularly in encrusting forms which also have extensive secondary calcification

New physical activity spaces in deprived neighborhoods: Does it change outdoor play and sedentary behavior? A natural experiment

Background: We used the introduction of dedicated physical activity (PA) spaces in Rotterdam, the Netherlands, to study the impact of reducing distance to dedicated PA spaces on outdoor play and sedentary behavior, and to evaluate if these effects were similar between population subgroups. Methods: We included 1841 Dutch children from the Generation R Study who participated at two subsequent measurement waves when the children were, on average, 6.0 and 9.7 years old. None of these children lived within 600 m of a dedicated PA space at baseline, and during follow-up 171 children became exposed to 13 new PA spaces within 600 m from home. Individual-level fixed-effects models were used to evaluate changes in distances (determined by Geographical Information Systems (GIS)) from home to the nearest new dedicated PA space, to parent-reported outdoor play and sedentary behavior. Results: The introduction of a dedicated PA space within 600 m from home, and the reduction of the distance per 100 m, did not affect outdoor play or sedentary behaviors. At p < 0.1, significant interaction terms were found between the introduction of the PA spaces and indicators of family socioeconomic position. Although not statistically significant, stratified analyses showed a consistent pattern, suggesting that reducing the distance to the nearest PA space increased outdoor play for children from parents with lower levels of education. However, they also showed a non-significant increase in sedentary behaviors for children from families with net household income below average Dutch income, and for children from a non-Dutch ethnicity. Conclusions: Introducing dedicated PA spaces may be a promising approach to increase outdoor play for children from more socioeconomically disadvantaged families, but larger studies are needed to contribute to the evidence

Cyclic nucleotide specificity of the activator and catalytic sites of a cGMP-stimulated cGMP phosphodiesterase from Dictyostelium discoideum

The cellular slime mold Dictyostelium discoideum has an intracellular phosphodiesterase which specifically hydrolyzes cGMP. The enzyme is activated by low cGMP concentrations, and is involved in the reduction of chemoattractant-mediated elevations of cGMP levels. The interaction of 20 cGMP derivatives with the activator site and with the catalytic site of the enzyme has been investigated. Binding of cGMP to the activator site is strongly reduced (more than 80-fold) if cGMP is no longer able to form a hydrogen bond at N2H2 or O2’H. Modifications at N7, C8, O3’ and O5’ induce only a small reduction of binding affinity. A cyclic phosphate structure, as well as a negatively charged oxygen atom at phosphorus, are essential to obtain activation of the enzyme. Substitution of the axial exocyclic oxygen atom by sulphur is tolerated; modification of the equatorial oxygen atom reduces the binding activity of cGMP to the activator site by 90-fold. Binding of cGMP to the catalytic site is strongly reduced if cGMP is modified at N1H, C6O, C8 and O3’, while modifications at N2H2, N3, N7, O2’H, and O5’ have minor effects. Both exocyclic oxygen atoms are important to obtain binding of cGMP to the catalytic site. The results indicate that activation of the enzyme by cGMP and hydrolysis of cGMP occur at different sites of the enzyme. cGMP is recognized at these sites by different types of molecular interaction between cGMP and the protein. cGMP derivatives at concentrations which saturate the activator site do not induce the same degree of activation of the enzyme (activation 2.3-6.6-fold). The binding affinities of the analogues for the activator site and their maximal activation are not correlated. Our results suggest that the enzyme is activated because cGMP bound to the activator site stabilizes a state of the enzyme which has a higher affinity for cGMP at the catalytic site.

Western solidarity with Pussy Riot and the Twittering of cosmopolitan selves

This article aims to explain the widespread attention to contemporary protesting artists among Western audiences by focusing on the case of Pussy Riot. Social movement scholarship provides a first step into understanding how Pussy Riot legitimately protests Russian politics through its punk performances. It then turns to the concept of cosmopolitanism as a performance in everyday life to explain Pussy Riot's appeal among Western audiences. By collecting and analyzing 9001 tweets through a thematic hashtag analysis and topic modeling, this article analyzes how audiences talk about Pussy Riot and shows how Twitter affords users to perform cosmopolitan selves by sharing their ideas and experiences on Pussy Riot with others. Although we distinguish between four types of cosmopolitan selves, the results clearly show Pussy Riot is mainly reflected upon in a media context: Twitter users predominantly talk about Pussy Riot's media appearances rather than readily engage with its explicit political advocacy

Charged stripes from alternating static magnetic field

We motivate and perform a calculation of the energy of a cold fluid of charged fermions in the presence of a striped magnetic background. We find that a non-trivial value for the doping density on the walls is preferredComment: RevTeX, 3 pages, 3 encapsulated PostScript figure

Experimental investigation of the loss characteristics of superconductors for AC power applications

Recent studies confirm the economical feasibility of the application of superconductors in AC power apparatus. The low-loss conductor which has been proposed still only exists in theory. Simple calculations show that the economic criterion described by Ogasawara and Hlásnik is inaccurate because of an oversimplified hysteresis loss formula. A necessary modification shows that stricter demands will have to be made. As production of ultrafine filaments is a big technological problem, final diameter reduction by rolling instead of drawing is proposed. The expected better performance of a rolled composite has been verified experimentally in test coils as well as in transformer geometry. Experimental set-up and results are presented

Structure of the axonal surface recognition molecule neurofascin and its relationship to a neural subgroup of the immunoglobulin superfamily

The chick axon-associated surface glycoprotein neurofascin is implicated in axonal growth and fasciculation as revealed by antibody perturbation experiments. Here we report the complete cDNA sequence of neurofascin. It is composed of four structural elements: At the NH2 terminus neurofascin contains six Ig-like motifs of the C2 subcategory followed by four fibronectin type III (FNIII)-related repeats. Between the FNIII-like repeats and the plasma membrane spanning region neurofascin contains a domain 75-amino acid residues-long rich in proline, alanine and threonine which might be the target of extensive O-linked glycosylation. A transmembrane segment is followed by a 113-amino acid residues-long cytoplasmic domain. Sequence comparisons indicate that neurofascin is most closely related to chick Nr-CAM and forms with L1 (Ng-CAM) and Nr-CAM a subgroup within the vertebrate Ig superfamily. Sequencing of several overlapping cDNA probes reveals interesting heterogeneities throughout the neurofascin polypeptide. Genomic Southern blots analyzed with neurofascin cDNA clones suggest that neurofascin is encoded by a single gene and its pre-mRNA might be therefore alternatively spliced. Northern blot analysis with domain specific probes showed that neurofascin mRNAs of about 8.5 kb are expressed throughout development in embryonic brain but not in liver. Isolation of neurofascin by immunoaffinity chromatography results in several molecular mass components. To analyze their origin the amino-terminal sequences of several neurofascin components were determined. The NH2-terminal sequences of the 185, 160, and 110-135 kD components are all the same as the NH2 termini predicted by the cDNA sequence, whereas the other neurofascin components start with a sequence found in a putative alternatively spliced segment between the Ig- and FNIII-like part indicating that they are derived by proteolytic cleavage. A combination of enzymatic and chemical deglycosylation procedures and the analysis of peanut lectin binding reveals O- and N-linked carbohydrates on neurofascin components which might generate additional heterogeneity

Differential predictive value of parents' and teachers' reports of children's problem behaviors: A longitudinal study

This study investigated the prediction of signs of disturbance in 946 children originally aged 4 to 11 years from the general population across a 6-year period. Parents' and teachers' ratings obtained via the Child Behavior Checklist (CBCL) and Teacher's Report Form (TRF) were tested as predictors of (a) academic problems, (b) school behavior problems, (c) receipt of mental health services, (d) child's need for professional help, (e) suicidal behavior, and (f) police contacts. Total problem scores in the deviant range on the CBCL or TRF were significantly associated with poor outcomes 6 years later. The combination of deviant scores on both the CBCL and TRF was a powerful predictor of poor outcomes with 56% of the girls, and 36% of the boys with total problem scores in the deviant range on both instruments maladjusted 6 years later. The CBCL syndromes Attention Problems and Delinquent Behavior, and the TRF syndromes Delinquent Behavior, Somatic Complaints, and Social Problems significantly predicted poor outcomes. Teachers' reports predicted poor outcomes equally well or even somewhat better than parents' reports. It is important to include teacher information in the diagnostic assessment of children

Critical properties of loop percolation models with optimization constraints

We study loop percolation models in two and in three space dimensions, in which configurations of occupied bonds are forced to form closed loop. We show that the uncorrelated occupation of elementary plaquettes of the square and the simple cubic lattice by elementary loops leads to a percolation transition that is in the same universality class as the conventional bond percolation. In contrast to this an optimization constraint for the loop configurations, which then have to minimize a particular generic energy function, leads to a percolation transition that constitutes a new universality class, for which we report the critical exponents. Implication for the physics of solid-on-solid and vortex glass models are discussed.Comment: 8 pages, 8 figure