Even-denominator fractional quantum Hall physics in ZnO

The fractional quantum Hall (FQH) effect emerges in high-quality two-dimensional electron systems exposed to a magnetic field when the Landau-level filling factor, ν_e, takes on a rational value. Although the overwhelming majority of FQH states have odd-denominator fillings, the physical properties of the rare and fragile even-denominator states are most tantalizing in view of their potential relevance for topological quantum computation. For decades, GaAs has been the preferred host for studying these even-denominator states, where they occur at ν_e = 5/2 and 7/2. Here we report an anomalous series of quantized even-denominator FQH states outside the realm of III–V semiconductors in the MgZnO/ZnO 2DES electron at ν_e = 3/2 and 7/2, with precursor features at 9/2; all while the 5/2 state is absent. The effect in this material occurs concomitantly with tunability of the orbital character of electrons at the chemical potential, thereby realizing a new experimental means for investigating these exotic ground states

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

Microwave spectroscopy of the low-filling-factor bilayer electron solid in a wide quantum well

At the low Landau filling factor termination of the fractional quantum Hall effect series, two-dimensional electron systems exhibit an insulating phase that is understood as a form of pinned Wigner solid. Here we use microwave spectroscopy to probe the transition to the insulator for a wide quantum well sample that can support single-layer or bilayer states depending on its overall carrier density. We find that the insulator exhibits a resonance which is characteristic of a bilayer solid. The resonance also reveals a pair of transitions within the solid, which are not accessible to dc transport measurements. As density is biased deeper into the bilayer solid regime, the resonance grows in specific intensity, and the transitions within the insulator disappear. These behaviours are suggestive of a picture of the insulating phase as an emulsion of liquid and solid components

Indoor environmental factors and acute respiratory illness in a prospective cohort of community-dwelling older adults

202209_bcwwAccepted ManuscriptRGCPublishe

Observation of type-I and type-II excitons in strained Si/SiGe quantum-well structures

The authors report photoluminescence (PL) measurement on a series of SiSiGe quantum-well structures that had different internal strain distributions. When each sample was placed in a high magnetic field, the field-dependent energy shift of the relevant PL peaks revealed either type-I or type-II exciton formation depending on the strain distribution. This observation is in agreement with theoretical modeling. The present investigation shows that type-I band alignment-desired for electroluminescent devices-can be achieved by strain engineering. © 2007 American Institute of Physics

Age structure of the workforce in growing and declining industries: evidence from Hong Kong

Industry-specific human capital, Industry upgrading, Sectoral shifts, J10, J23, J24,

Psychometric properties of EQ-5D-5L for use in patients with Graves’ disease

Abstract Background The EQ-5D-5 L is a commonly used generic measure of health. This study aimed to evaluate the psychometric properties of the EQ-5D-5 L in patients with Graves’ disease (GD). Methods A prospective cohort of patients with GD recruited at three public hospitals in Hong Kong completed the EQ-5D-5 L and ThyPRO-39 questionnaires at baseline, 1-month, and 6-month follow-ups. Convergent validity was tested by examining the Spearman correlation between EQ-5D-5 L and ThyPRO-39 scores at baseline. 1-month test-retest reliability was assessed by Intraclass Correlation Coefficient (ICC), Gwet’s Agreement Coefficient 2 (AC2), and percentage agreement. Responsiveness of EQ-5D-5 L index and EQ-VAS scores was assessed using effect size statistics (standardized effect size [SES] and standardized response mean [SRM]). Results Of 125 recruited patients, 101 (80.8%) and 100 (80.0%) patients were followed up at 1- and 6-month, respectively. For convergent validity, there was a moderate negative correlation between EQ-5D-5 L index or EQ-VAS score and ThyPRO-39 overall QoL-impact score (-0.350, -0.451), between EQ-VAS score and composite score (-0.483), and strong negative correlation between EQ-5D-5 L index score and composite score (-0.567). The Gwet’s AC2 and percentage agreement were the highest in self-care (0.964 and 0.967), followed by mobility (0.952 and 0.962), usual activities (0.934 and 0.948), pain/discomfort (0.801 and 0.887), and anxiety/depression (0.788 and 0.882). The ICC for the EQ-5D-5 L index and the EQ-VAS was 0.707 and 0.700. For patients who reported having ‘worsened’ health at 6-month follow-up, the SES and SRM were − 0.66 and − 0.42 for EQ-5D-5 L index and − 1.15 and − 1.00 for EQ-VAS, respectively. Conclusions The EQ-5D-5 L demonstrated convergent validity, test-retest reliability, and responsiveness to worsened health status among patients with GD

Strong coulomb drag and broken symmetry in double-layer graphene

Contains fulltext : 103786.pdf (author's version ) (Open Access

Microwave spectroscopic observation of distinct electron solid phases in wide quantum wells

In high magnetic fields, two-dimensional electron systems can form a number of phases in which interelectron repulsion plays the central role, since the kinetic energy is frozen out by Landau quantization. These phases include the well-known liquids of the fractional quantum Hall effect, as well as solid phases with broken spatial symmetry and crystalline order. Solids can occur at the low Landau-filling termination of the fractional quantum Hall effect series but also within integer quantum Hall effects. Here we present microwave spectroscopy studies of wide quantum wells that clearly reveal two distinct solid phases, hidden within what in d.c. transport would be the zero diagonal conductivity of an integer quantum-Hall-effect state. Explanation of these solids is not possible with the simple picture of a Wigner solid of ordinary (quasi) electrons or holes