Magnetic Field Tomography

Neutral atoms may be trapped via the interaction of their magnetic dipole moment with magnetic field gradients. One of the possible schemes is the cloverleaf trap. It is often desirable to have at hand a fast and precise technique for measuring the magnetic field distribution. We introduce a novel diagnostic tool for instantaneous imaging the equipotential lines of a magnetic field within a region of space (the vacuum recipient) that is not accessible to massive probes. Our technique is based on spatially resolved observation of the fluorescence emitted by a hot beam of sodium atoms crossing a thin slice of resonant laser light within the magnetic field region to be investigated. The inhomogeneous magnetic field spatially modulates the resonance condition between the Zeeman-shifted hyperfine sublevels and the laser light and therefore the amount of scattered photons. We demonstrate this technique by mapping the field of our cloverleaf trap in three dimensions under various conditions.Comment: 8 pages, 8 figure

Impurity assisted nanoscale localization of plasmonic excitations in graphene

The plasmon modes of pristine and impurity doped graphene are calculated, using a real-space theory which determines the non-local dielectric response within the random phase approximation. A full diagonalization of the polarization operator is performed, allowing the extraction of all its poles. It is demonstrated how impurities induce the formation of localized modes which are absent in pristine graphene. The dependence of the spatial modulations over few lattice sites and frequencies of the localized plasmons on the electronic filling and impurity strength is discussed. Furthermore, it is shown that the chemical potential and impurity strength can be tuned to control target features of the localized modes. These predictions can be tested by scanning tunneling microscopy experiments.Comment: 5 pages, 4 figure

Consumer Storytelling of Brand Archetypal Enactments

The study here probes the perspective that consumers use certain brands as actors that play roles in the consumers’ lives and that help consumers as protagonists to enact roles that give them the feelings of achievement, well-being, and/or emotional excitement. The method enables the uncovering of archetypes as unconscious forces that drive consumers to specific actions implicitly and to a less extent, explicitly. The study employs two techniques: degrees-of-freedom analysis (DFA) to test whether or not consumer stories fit a given archetypal theme and visual narrative art (VNA) to confirm whether or not consumer’s own stories enact a specific archetype and how such enactments are done. This study offers an alternative for survey auditing consumer-brand relationships; the study here describes and explains the importance of narratives in consumer behaviour and the use of archetypes as universal themes that aid understanding of brand-consumer relationships. The study describes DFA and VNA with two examples of the use of these analytics

Reduction of the transverse effective charge of optical phonons in ZnO under pressure

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 96, 231906 (2010) and may be found at https://doi.org/10.1063/1.3447798."From Raman scattering on a-plane wurtzite ZnO crystals we obtained a decreasing splitting between longitudinal and transversal optical phonons with A1 and E1 symmetry as a function of hydrostatic pressure up to 5.5 GPa. Consequently, the transverse effective charge (e∗T) exhibits a strong reduction with increasing pressure, yielding 2.17–14.6×10−3 P/GPa and 2.04–13.7×10−3 P/GPa (in units of the elementary charge) for the A1 and E1 phonons, respectively. We find a clear systematic in the linear pressure coefficient of e∗T with bond polarity for the series of wide-band gap semiconductors SiC, AlN, GaN, and ZnO.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement

Statistical analysis of nutrient data quality (nitrate and phosphate), applied to useful predictor models in the northwestern Mediterranean Sea

Se ha analizado estadísticamente un conjunto de datos de 12 campañas oceanográficas (realizadas de 1979 a 1983), abarcando dos regiones en el mar Mediterráneo noroccidental (golfo de León y mar Catalán), relacionando el nitrato y el fosfato con el silicato, la salinidad y la profundidad. El análisis ha proporcionado una visión de la calidad de los datos y un modelo de predicción para estos nutrientes por debajo de la capa superficial. Los resultados del análisis estadístico han mostrado que las ecuaciones de regresión (nitrato- profundidad y fosfato-salinidad) de algunas campañas del golfo de León no presentaron diferencias significativas (P = 0,05), indicando que estas relaciones no cambian en esta área, principalmente en verano y otoño. Se puede observar una relación significativa entre nitrato y fosfato con salinidad y profundidad (regresión múltiple), sugiriendo que las distribuciones del nitrato y del fosfato en la capa intermedia están relacionadas con la mezcla de las masas de agua y la degradación de la materia orgánica. Los datos de fosfato mostraron una variancia elevada y errores, probablemente debido a cuestiones de metodología y análisis químico. Por debajo de la masa de Agua Levantina Intermedia, los resultados del ANOVA han mostrado que no hay una variación significativa de las concentraciones de nitrato y fosfato en la columna de agua. Por otro lado, se puede observar una variación espacial y temporal en esta capa.A dataset comprising 12 oceanographic cruises (from 1979 to 1983), covering two regions in the Northwestern Mediterranean Sea (Gulf of Lyon and Catalan Sea), was statistically analysed for nitrate and phosphate relationships with silicate, salinity and depth. This analysis provided a preliminary assessment of the data's quality, as well as a predictor model of these nutrients below the surface layer. Results from the statistical analysis showed no significant difference (P = 0.05), between the regression equations (nitrate-depth and phosphate-salinity) of most cruises in the Gulf of Lyon, indicating that these relationships do not change in this area, particularly in summer and autumn. A significant relationship between nitrate and phosphate with salinity and depth (multiple regression) was observed, suggesting that nitrate and phosphate distribution in the intermediate level are significantly related to the mixture of the water masses and the degradation of organic matter. The phosphate data showed a wide variance and a bias, probably due to procedural problems in the chemical analysis. Below the Intermediate Levantine Water, results from the ANOVA showed no significant variation of the phosphate and nitrate concentrations in the water column. However, a spatial and temporal variation was observed in this level.Instituto Español de Oceanografí

Carnauba wax enhances the insecticidal activity of entomopathogenic fungi against the blowfly Lucilia sericata (Diptera: Calliphoridae)

Abstract Blowfly, Lucilia sericata (Diptera: Calliphoridae), is a problematic synanthropic insect pest, a vector of microbial pathogens, and the causal agent of secondary myiasis. Fungal biopesticides are considered eco-friendly tools, alternative to synthetic pesticides, for the control of arthropod pests; however, to date, little is known about their bioactivity against blowflies. In this study, we assessed the insecticidal activity of three well-known entomopathogenic fungi, Beauveria bassiana, Beauveria pseudobassiana and Akanthomyces muscarius against L. sericata. In addition, we tested powdered carnauba wax as an electrically charged dust carrier in an attempt to enhance the virulence of fungal spores. Pathogenicity tests on adult flies, by adult immersion in conidial suspension (108 conidia mL−1), showed that the median lethal time (LT50) was 5.3, 5.9, and 6.2 days for B. bassiana, A. muscarius and B. pseudobassiana, respectively. In topical tests, when 108 dry conidia were mixed with or without carnauba wax, the LT50 was 7.7, 10.2, and 14 days without this carrier and 6.9, 8.6, and 13.8 days with it for B. bassiana, B. pseudobassiana and A. muscarius, respectively. Overall, our findings showed that, among the tested fungi, B. bassiana was the most virulent when formulated as a dry powder with carnauba wax, which greatly improved fungal efficacy against the blowfly. We discuss the utility of carnauba wax for electrostatic formulation powder of fungal spores in the integrated management of blowflies as an environmentally sustainable tool to reduce the over-reliance on chemical insecticides and their risk of resistance

Partial-Transfer Absorption Imaging: A versatile technique for optimal imaging of ultracold gases

Partial-transfer absorption imaging is a tool that enables optimal imaging of atomic clouds for a wide range of optical depths. In contrast to standard absorption imaging, the technique can be minimally-destructive and can be used to obtain multiple successive images of the same sample. The technique involves transferring a small fraction of the sample from an initial internal atomic state to an auxiliary state and subsequently imaging that fraction absorptively on a cycling transition. The atoms remaining in the initial state are essentially unaffected. We demonstrate the technique, discuss its applicability, and compare its performance as a minimally-destructive technique to that of phase-contrast imaging.Comment: 10 pages, 5 figures, submitted to Review of Scientific Instrument

Does (re-)entering the labour market at advanced ages protect against cognitive decline?:A matching difference-in-differences approach

peer reviewedBACKGROUND: While prolonged labour market participation becomes increasingly important in ageing societies, evidence on the impacts of entering or exiting work beyond age 65 on cognitive functioning is scarce. METHODS: We use data from two large population-representative data sets from South Korea and the USA to investigate and compare the effects of the labour market (re-)entry and exit by matching employment and other confounder trajectories prior to the exposure. We chose the Korean Longitudinal Study of Aging (N=1872, 2006-2020) for its exceptionally active labour participation in later life and the Health and Retirement Study (N=4070, 2006-2020) for its growing inequality among US older adults in labour participation. We use the matching difference-in-differences (DID) method, which allows us to make causal claims by reducing biases through matching. RESULTS: We find general positive effects of entering the labour market in South Korea (DID estimate: 0.653, 95% CI 0.167 to 1.133), while in the USA such benefit is not salient (DID estimate: 0.049, 95% CI -0.262 to 0.431). Exiting the late-life labour market leads to cognitive decline in both South Korea (DID estimate: -0.438, 95% CI -0.770 to -0.088) and the USA (DID estimate: -0.432, 95% CI -0.698 to -0.165). CONCLUSIONS: Findings suggest that Korean participants cognitively benefited from late-life labour market participation, while US participants did not. Differences in participant characteristics and reasons for labour market participation may have led to the differential findings. We found the negative effects of exiting the late-life labour force in both countries