A Comparison of Results from a Spanish and English Mail Survey: Effects of Instruction Placement on Item Missingness

Few research studies compare results from self-administered bilingual paper questionnaires on how the positioning of skip instructions may affect the respondent’s ability to follow skip patterns. Using data from the 2004 and 2005 of the Phase 5 Pregnancy Risk Assessment Monitoring System (PRAMS) mail survey questionnaire, this paper attempts to fill this gap. We examined whether the positioning of skip instructions can produce differences in item nonresponse rates in subsequent items and how results compare between English and Spanish language questionnaires. These results will be of interest to designers of bilingual self-administered survey questionnaires in guiding respondents through the intended navigational path with skip patterns

Nonlinearity in the Dark: Broadband Terahertz Generation with Extremely High Efficiency

Plasmonic metamaterials and metasurfaces offer new opportunities in developing high performance terahertz emitters and detectors beyond the limitations of conventional nonlinear materials. However, simple meta-atoms for second-order nonlinear applications encounter fundamental trade-offs in the necessary symmetry breaking and local-field enhancement due to radiation damping that is inherent to the operating resonant mode and cannot be controlled separately. Here we present a novel concept that eliminates this restriction obstructing the improvement of terahertz generation efficiency in nonlinear metasurfaces based on metallic nanoresonators. This is achieved by combining a resonant dark-state metasurface, which locally drives nonlinear nanoresonators in the near field, with a specific spatial symmetry that enables destructive interference of the radiating linear moments of the nanoresonators, and perfect absorption via simultaneous electric and magnetic critical coupling of the pump radiation to the dark mode. Our proposal allows eliminating linear radiation damping, while maintaining constructive interference and effective radiation of the nonlinear components. We numerically demonstrate a giant second-order nonlinear susceptibility around Hundred-Billionth m/V, a one order improvement compared with the previously reported split-ring-resonator metasurface, and correspondingly, a 2 orders of magnitude enhanced terahertz energy extraction should be expected with our configuration under the same conditions. Our study offers a paradigm of high efficiency tunable nonlinear metadevices and paves the way to revolutionary terahertz technologies and optoelectronic nanocircuitry.Comment: 6 pages, 4 figure

Artificial Perfect Electric Conductor-Perfect Magnetic Conductor Anisotropic Metasurface for Generating Orbital Angular Momentum of Microwave with Nearly Perfect Conversion Efficiency

published_or_final_versio

Module Implementation and Modulation Strategy for Sensorless Balancing in Modular Multilevel Converters

Modules with series and parallel connectivity add new features and operation modes to modular multilevel converters (MMCs). Compared to full- and half-bridges, the series/parallel modules allow sensorless module balancing and reduce conduction loss with the same semiconductor area. However, in high-voltage applications with limited switching rates, the sensorless operation of the series/parallel modules suffers from large charge-balancing currents. This paper introduces a series/parallel module variant with a small port inductor. The port inductor suppresses the charge-balancing current despite low switching rates. We also propose a carrier-based modulation framework and show the importance of the carrier assignment in terms of efficiency and balancing. The proposed module and the modulation method are verified on a lab setup with module switching rates down to 200 Hz. The module voltages are kept within a narrow band with the charge-balancing currents below 5% of the arm current. The experimental results show practicality and advantages of the new series/parallel modules in high-voltage MMC applications

Irregular primes with respect to Genocchi numbers and Artin's primitive root conjecture

We introduce and study a variant of Kummer's notion of (ir)regularity of primes which we call G-irregularity and it is based on Genocchi numbers $G_n$, rather than Bernoulli number $B_n.$ We say that an odd prime $p$ is G-irregular if it divides at least one of the integers $G_2,G_4,\ldots, G_{p-3}$, and G-regular otherwise. We show that, as in Kummer's case, G-irregularity is related to the divisibility of some class number. Furthermore, we obtain some results on the distribution of G-irregular primes. In particular, we show that each primitive residue class contains infinitely many G-irregular primes and establish non-trivial lower bounds for their number up to a given bound $x$ as $x$ tends to infinity. As a by-product, we obtain some results on the distribution of primes in arithmetic progressions with a prescribed near-primitive root

Prevalence of Bronchial Asthma in 6 To 17 years Old School Children of Urban Chennai in Lower Middle Class/Lower Income Groups

OBJECTIVES: Aim of the study is to determine the prevalence of asthma among school children between 6 to17 years In Lower Middle Class / Lower Income Groups of urban Chennai and to analyse the various risk factors associated with those diagnosed with asthma. METHODS: We surveyed 1894 school children between 6 to 17 years using the questionnaires .For children between 6 to 12 years, the parents were made to answer and for children between 13 to 17 years, the children themselves answered the questionnaires. The children whose answer is Yes to atleast one of the four questions were considered as probable asthmatics and the diagnosis of asthma in those identified as probable asthmatic was done by detailed history and clinical examination. RESULTS: Out of 1894 children we surveyed, 156 children were considered as probable asthmatics and 85 children were diagnosed as asthmatics. The prevalence of bronchial asthma was 4.5%. There is a significant correlation between family H/O asthma and asthma and also there is a significant correlation between allergic rhinitis and asthma. Obesity is a significant comorbidity associated with asthma. CONCLUSION: Easy Breathing Survey questionnaires and detailed history and clinical examination can be used for estimating prevalence of asthma in large population

Ferromagnetism in 2p Light Element-Doped II-oxide and III-nitride Semiconductors

II-oxide and III-nitride semiconductors doped by nonmagnetic 2p light elements are investigated as potential dilute magnetic semiconductors (DMS). Based on our first-principle calculations, nitrogen doped ZnO, carbon doped ZnO, and carbon doped AlN are predicted to be ferromagnetic. The ferromagnetism of such DMS materials can be attributed to a p-d exchange-like p-p coupling interaction which is derived from the similar symmetry and wave function between the impurity (p-like t_2) and valence (p) states. We also propose a co-doping mechanism, using beryllium and nitrogen as dopants in ZnO, to enhance the ferromagnetic coupling and to increase the solubility and activity

The crystal structure of the peptide-binding fragment from the yeast Hsp40 protein Sis1

AbstractBackground: Molecular chaperone Hsp40 can bind non-native polypeptide and facilitate Hsp70 in protein refolding. How Hsp40 and other chaperones distinguish between the folded and unfolded states of proteins to bind non-native polypeptides is a fundamental issue.Results: To investigate this mechanism, we determined the crystal structure of the peptide-binding fragment of Sis1, an essential member of the Hsp40 family from Saccharomyces cerevisiae. The 2.7 Å structure reveals that Sis1 forms a homodimer in the crystal by a crystallographic twofold axis. Sis1 monomers are elongated and consist of two domains with similar folds. Sis1 dimerizes through a short C-terminal stretch. The Sis1 dimer has a U-shaped architecture and a large cleft is formed between the two elongated monomers. Domain I in each monomer contains a hydrophobic depression that might be involved in binding the sidechains of hydrophobic amino acids.Conclusions: Sis1 (1–337), which lacks the dimerization motif, exhibited severe defects in chaperone activity, but could regulate Hsp70 ATPase activity. Thus, dimer formation is critical for Sis1 chaperone function. We propose that the Sis1 cleft functions as a docking site for the Hsp70 peptide-binding domain and that Sis1–Hsp70 interaction serves to facilitate the efficient transfer of peptides from Sis1 to Hsp70

Influence of grain-refiner addition on the morphology of fe-bearing intermetallics in a semi-solid processed Al-Mg-Si alloy

© The Minerals, Metals & Materials Society and ASM International 2013The three-dimensional morphologies of the Fe-bearing intermetallics in a semisolid-processed Al-Mg-Si alloy were examined after extracting the intermetallics. α -AlFeSi and β-AlFeSi are the major Fe-bearing intermetallics. Addition of Al-Ti-B grain refiner typically promotes β-AlFeSi formation. β-AlFeSi was observed with a flat, plate-like morphology with angular edges in the alloy with and without grain refiner, whereas α -AlFeSi was observed as "flower"-like morphology in the alloy with grain refiner. © 2013 The Minerals, Metals & Materials Society and ASM International