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Online self-reported 24-h dietary recall systems promise increased feasibility of dietary assessment. Comparison against interviewer-led recalls established their convergent validity; however, reliability and criterion-validity information is lacking. The validity of energy intakes (EI) reported using Intake24, an online 24-h recall system, was assessed against concurrent measurement of total energy expenditure (TEE) using doubly labelled water in ninety-eight UK adults (40–65 years). Accuracy and precision of EI were assessed using correlation and Bland–Altman analysis. Test–retest reliability of energy and nutrient intakes was assessed using data from three further UK studies where participants (11–88 years) completed Intake24 at least four times; reliability was assessed using intra-class correlations (ICC). Compared with TEE, participants under-reported EI by 25 % (95 % limits of agreement −73 % to +68 %) in the first recall, 22 % (−61 % to +41 %) for average of first two, and 25 % (−60 % to +28 %) for first three recalls. Correlations between EI and TEE were 0·31 (first), 0·47 (first two) and 0·39 (first three recalls), respectively. ICC for a single recall was 0·35 for EI and ranged from 0·31 for Fe to 0·43 for non-milk extrinsic sugars (NMES). Considering pairs of recalls (first two v. third and fourth recalls), ICC was 0·52 for EI and ranged from 0·37 for fat to 0·63 for NMES. EI reported with Intake24 was moderately correlated with objectively measured TEE and underestimated on average to the same extent as seen with interviewer-led 24-h recalls and estimated weight food diaries. Online 24-h recall systems may offer low-cost, low-burden alternatives for collecting dietary information.
Oxidative stress is implicated in the aetiology of schizophrenia, and the antioxidant defence system (AODS) may be protective in this illness. We examined the major antioxidant glutathione (GSH) in prefrontal brain and its correlates with clinical and demographic variables in schizophrenia.
GSH levels were measured in the dorsolateral prefrontal region of 28 patients with chronic schizophrenia using a magnetic resonance spectroscopy sequence specifically adapted for GSH. We examined correlations of GSH levels with age, age at onset of illness, duration of illness, and clinical symptoms.
We found a negative correlation between GSH levels and age at onset (r = −0.46, p = 0.015), and a trend-level positive relationship between GSH and duration of illness (r = 0.34, p = 0.076).
Our findings are consistent with a possible compensatory upregulation of the AODS with longer duration of illness and suggest that the AODS may play a role in schizophrenia.
The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural–geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.
Norovirus, a major cause of gastroenteritis in people of all ages worldwide, was first reported in South Korea in 1999. The most common causal agents of pediatric acute gastroenteritis are norovirus and rotavirus. While vaccination has reduced the pediatric rotavirus infection rate, norovirus vaccines have not been developed. Therefore, prediction and prevention of norovirus are very important. Norovirus is divided into genogroups GI–GVII, with GII.4 being the most prevalent. However, in 2012–2013, GII.17 showed a higher incidence than GII.4 and a novel variant, GII.P17-GII.17, appeared. In this study, 204 stool samples collected in 2013–2014 were screened by reverse transcriptase-polymerase chain reaction; 11 GI (5.39%) and 45 GII (22.06%) noroviruses were identified. GI.4, GI.5, GII.4, GII.6 and GII.17 were detected. The whole genomes of the three norovirus GII.17 were sequenced. The whole genome of GII.17 consists of three open reading frames of 5109, 1623 and 780 bp. Compared with 20 GII.17 strains isolated in other countries, we observed numerous changes in the protruding P2 domain of VP1 in the Korean GII.17 viruses. Our study provided genome information that might aid in epidemic prevention, epidemiology studies and vaccine development.
Introduction: Competence committees (CCs) struggle with incorporating professionalism issues into resident progression decisions. This study examined how professionalism concerns influence individual faculty decisions about resident progression using simulated CC reviews. Methods: In 2017, the investigators conducted a survey of 25 program directors of Royal College emergency medicine residency training programs in Canada and those faculty members who are members of the CCs (or equivalent) at their home institution. The survey contained twelve resident portfolios, each containing formative and summative information available to a CC for making progression decisions. Six portfolios outlined residents progressing as expected and six were not progressing as expected. Further, a professionalism variable (PV) was added to six portfolios, evenly split between those residents progressing as expected and not. Participants were asked to make progression decisions based on each portfolio. Results: Raters were able to consistently identify a resident needing an educational intervention versus those who did not. When a PV was added, the consistency among raters decreased by 34.2% in those residents progressing as expected, versus increasing by 3.8% in those not progressing as expected (p = 0.01). Conclusion: When using an unstructured review of a simulated resident portfolio, individual reviewers can better discriminate between trainees progressing as expected when professionalism concerns are added. Considering this, educators using a competence committee in a CBME program must have a system to acquire and document professionalism issues to make appropriate progress decisions.
We develop experimentally and theoretically plasmonic and photonic crystals for enhancing thin film silicon solar cells. Thin film amorphous silicon (a-Si:H) solar cells suffer from decreased absorption of red and near-infrared photons, where the photon absorption length is large. Simulations predict maximal light absorption for a pitch of 700-800 nm for photonic crystal hole arrays in silver or ZnO/Ag back reflectors, with absorption increases of ~12%. The photonic crystal improves over the ideal randomly roughened back reflector (or the ‘4n2 limit’) at wavelengths near the band edge. We fabricated metallic photonic crystal back-reflectors using photolithography and reactive-ion etching. We conformally deposited a-Si:H solar cells on triangular lattice hole arrays of pitch 760 nm on silver back-reflectors. Electron microscopy demonstrates excellent long range periodicity and conformal a-Si:H growth. The measured quantum efficiency increases by 7-8 %, relative to a flat reflector reference device, with enhancement factors exceeding 6 at near-infrared wavelengths. The photonic crystal back reflector strongly diffracts light and increases optical path lengths of solar photons.
A cost-effective fabrication method to engineer metamaterial structures with micrometersize features and novel mechanical properties, which are suitable for terahertz applications, is reported herein. The effective metamaterial parameter extraction procedure is employed with the Kramers-Kronig relation to analyze the effective parameters of single- and multilayer metamaterial structures.
Resonant optical dipole antennas, consisting either of two arms coupled by a small gap or of a single, uncoupled arm only, are fabricated by the application of electron beam lithography and gold evaporation. Using dark-field microscopy, scattering spectra of structures with varied antenna arm length and varied gap size are obtained. The results show not only a spectral redshift for coupled structures compared to single arm structures, but also that the far-field scattering intensity is significantly higher for two arm structures with gap. In addition to the dipole structures, first fabrication results on quadrupole antennas and split-ring antennas are presented, offering novel pathways for an enhancement of the optical response function.
We have developed a novel strategy for elaborating composite plasmonic nanomaterials in a well controlled manner. Combining several techniques commonly used in microelectronic engineering, namely sputtering deposition, thermal oxidation, ultra low energy ion implantation, focused ion beam lithography, thermal or laser annealing, we have obtained 3D patterned optical layers. Their spatial and spectral responses take benefit of optical interference, plasmonic resonance effects and coupling between excitations in both near and far field regime. Moreover these structures show high level of uniformity, reproducibility and stability, and they preserve flat and chemically uniform surfaces.
The surface plasmon enhanced transmission of light though a plasmonic crystal provides a novel approach for fabricating an optical modulator. The extraordinary transmission passing though these patterned metallic films is very sensitive to the surface dielectric environment. In this study, hexagonal lattice plasmonic crystals were fabricated with a self-assembly technique. Arrays of gold nano-holes or bumps with 500/600 nm periodicity were used to test the sensitivity of plasmon resonance wavelength for liquids and polymers with different dielectric constants. A nonlinear optical polymer P3HT coated onto the plasmonic crystal and pumped with 475 nm laser was found to modulate the transmission of a normally incident red light at 670 nm.
A layer of silver nanoparticles created by thermal annealing of evaporated silver films can increase the photocurrents in silicon-on-insulator (SOI) devices by fivefold or more, but significant enhancements have been restricted to wavelengths greater than 800 nm. Here we report a significant enhancement of photoconductance at shorter wavelengths (500-750 nm) by using a monolayer of silver nanoparticles transferred from a colloidal suspension. Photocurrents on SOI increased in the 500-750 nm spectral range with the addition of silver nanoparticles, with enhancements more than two times; enhancements at longer wavelengths were small, in contrast to results with annealed silver films. We prepared similar colloidal silver nanoparticle monolayers layers on nanocrystalline silicon solar cells with conducting oxide top layers. There is an overall decrease in the quantum efficiency of these cells with the deposition of silver nanoparticles. We attribute these effects to the substantial substrate-mediated changes in the localized surface plasmon resonance frequencies of the differing nanoparticle configurations.
Localized Surface Plasmon Resonances (LSPR) in rod-shaped Gold (Au) nanoparticles patterned with Electron Beam Lithography (EBL) technique are observed via reflectance measurements. Resonance peaks corresponding to the principal axes of the nano-rods are shown to be affected by each other. Excitation of one of the peaks is found to result in a decrease in the peak intensity of the resonance through the other axis. Arrays of Au nanoparticles with constant width and thickness but increasing length are examined for further understanding of the effect. As the particle length increased from 70 nm to 300 nm, resonance peak wavelength shifted from 650 nm to 1200 nm. Total reflectance intensities of samples with varying principal axis dimensions obtained through the spectral region of interest are also examined to see the relation between contributing electrons and total amount of reflected intensity. Results corresponding to both polarized and unpolarized illumination of samples are presented together to gain better understanding of lowered reflectance peak intensities obtained from the latter case. Based on the results obtained so far, nano-sized metal rods are promising tools for optically switched intensity modulation in the visible and near-IR region.
The second order nonlinear optical (NLO) properties of two different ionic selfassembled multilayer (ISAM) films combined with Ag nanoparticles have been investigated. The plasmon resonances in the Ag particles concentrate the incident light, markedly increasing in the NLO efficiencies of the films. We find that the efficiency enhancement is significantly larger in conventional ISAM films compared to films made using a hybrid covalent ISAM technique (HCISAM), even though the intrinsic bulk second order non-linear susceptibility (χ(2)) is much larger for HCISAM films. We attribute this to the interfaces in HCISAM films being much easier to disrupt by external perturbations such as the metal deposition by which the nanoparticles are fabricated. We conclude that because the plasmon decay length is very short, the plasmonic enhancement of NLO effects primarily occurs at and near the film-particle interface. To discern the importance of the interfaces, we surrounded thin ISAM and HCISAM films with NLOinactive buffer layers, which confirmed this hypothesis, particularly in the case of HCISAM films.
Infrared absorption spectroscopy is a powerful tool for structural and functional studies of biomolecules. The technique enables direct access to the vibrational fingerprints of molecular bonds in the mid-infrared spectral region (3-20μm). Although intrinsic absorption cross-sections are nearly ten orders of magnitude greater than corresponding Raman cross-sections, they are still small in comparison with those of fluorescent molecules. Sensitivity improvements are therefore required for the method to be applicable to single molecule / molecular layer studies. In this work, we demonstrate the use of lithographically patterned arrays of nanoantennas to enhance the absorption signature of the protein amide-I and II backbone vibrations. Strong absorption signals from monolayer thickness films are obtained. By arranging ensembles of tailored antennas in specific lattices, higher quality factor resonances and increased near-field intensities are possible. These features are leveraged to obtain 104-105 fold signal enhancements and the direct measurement of vibrational spectra of proteins at zepto-mole sensitivity levels.
Three antidot arrays with FeNi alloy thickness of 20, 50 and 100 nm have been patterned using magnetron sputtering followed by the electron-beam lithography and lift-off technique. Ferromagnetic resonance technique was used to study dynamic properties of the antidot arrays. These results were compared with the measurements of continuous films with the same composition and thickness. Two distinct resonant fields have been observed for the bias field aligned with the edges of the square holes. Resonance peaks shifted towards each other and eventually merged when the in-plane bias field was rotated towards diagonal of the squares. This dependence has been explained in terms of magnetostatic energy associated with the square holes. The magnitude of this effect was decreasing for the arrays with the reduced thickness. The perpendicular and lateral quantized standing spin wave modes were detected in the reference films and the antidot arrays due to the perpendicular and lateral dimensional confinements.
Electromagnetic radiation beyond the diffraction limit with a particular polarization emerges as a need for plasmonic applications. One of these applications is all-optical magnetic recording, which requires circularly-polarized electromagnetic radiation. In this study, a plasmonic cross-dipole nano-antenna is illuminated with diffraction-limited linearly polarized radiation. An optimal configuration for the nano-antenna and the polarization angle of the incident light is identified to obtain linearly, circularly, and elliptically polarized optical spots beyond the diffraction limit. The Poincaré sphere representation is utilized to visually present calculated Stokes parameters for optical spots with linear, circular, and elliptical polarizations from specific antenna geometries.
Reciprocal space mapping can be efficiently carried out using a position-sensitive x-ray detector (PSD) coupled to a traditional double-axis diffractometer. The PSD offers parallel measurement of the total scattering angle of all diffracted x-rays during a single rocking-curve scan. As a result, a two-dimensional reciprocal space map can be made in a very short time similar to that of a one-dimensional rocking-curve scan. Fast, efficient reciprocal space mapping offers numerous routine advantages to the x-ray diffraction analyst. Some of these advantages arc the explicit differentiation of lattice strain from crystal orientation effects in strain-relaxed heteroepitaxial layers; the nondestructive characterization of the size, shape and orientation of nanocrystalline domains in ordered-alloy epilayers; and the ability to measure the average size and shape of voids in porous epilayers. Here, the PSD-based diffractometer is described, and specific examples clearly illustrating the advantages of complete reciprocal space analysis are presented.
A new ESCA (electron spectroscopy for chemical analysis) instrument has been developed to provide high sensitivity and efficient operation for laboratory analysis of composition and chemical bonding in very thin surface layers of solid samples. High sensitivity is achieved by means of the high-intensity, efficient X-ray source described by Davies and Herglotz at the 1968 Denver X-Ray Conference, in combination with the new electron energy analyzer described by Lee at the 1972 Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy. A sample chamber designed to provide for rapid introduction and replacement of samples has adequate facilities for various sample treatments and conditioning followed immediafely by ESCA analysis of the sample.
Examples of application are presented, demonstrating the sensitivity and resolution achievable with this instrument. Its usefulness in trace surface analysis is shown and some “chemical shifts” measured by the instrument are compared with those obtained by X-ray spectroscopy.