Novel Collective Effects in Integrated Photonics

Superradiance, the enhanced collective emission of energy from a coherent ensemble of quantum systems, has been typically studied in atomic ensembles. In this work we study theoretically the enhanced emission of energy from coherent ensembles of harmonic oscillators. We show that it should be possible to observe harmonic oscillator superradiance for the first time in waveguide arrays in integrated photonics. Furthermore, we describe how pairwise correlations within the ensemble can be measured with this architecture. These pairwise correlations are an integral part of the phenomenon of superradiance and have never been observed in experiments to date.Comment: 7 pages, 3 figure

A geometric approach to time evolution operators of Lie quantum systems

Lie systems in Quantum Mechanics are studied from a geometric point of view. In particular, we develop methods to obtain time evolution operators of time-dependent Schrodinger equations of Lie type and we show how these methods explain certain ad hoc methods used in previous papers in order to obtain exact solutions. Finally, several instances of time-dependent quadratic Hamiltonian are solved.Comment: Accepted for publication in the International Journal of Theoretical Physic

Coupling of acoustic cavitation with DEM-based particle solvers for modeling de-agglomeration of particle clusters in liquid metals

The aerospace and automotive industries are seeking advanced materials with low weight yet high strength and durability. Aluminum and magnesium-based metal matrix composites with ceramic micro- and nano-reinforcements promise the desirable properties. However, larger surface-area-to-volume ratio in micro- and especially nanoparticles gives rise to van der Waals and adhesion forces that cause the particles to agglomerate in clusters. Such clusters lead to adverse effects on final properties, no longer acting as dislocation anchors but instead becoming defects. Also, agglomeration causes the particle distribution to become uneven, leading to inconsistent properties. To break up clusters, ultrasonic processing may be used via an immersed sonotrode, or alternatively via electromagnetic vibration. This paper combines a fundamental study of acoustic cavitation in liquid aluminum with a study of the interaction forces causing particles to agglomerate, as well as mechanisms of cluster breakup. A non-linear acoustic cavitation model utilizing pressure waves produced by an immersed horn is presented, and then applied to cavitation in liquid aluminum. Physical quantities related to fluid flow and quantities specific to the cavitation solver are passed to a discrete element method particles model. The coupled system is then used for a detailed study of clusters’ breakup by cavitation

Influence of autonomic control on the specific intermittent performance of judo athletes

Judo is a high-intensity intermittent combat sport which causes cardiac adaptations both morphologically and related to the autonomic nervous system (ANS). Therefore, this study aims to verify the correlation between heart rate variability (HRV) at rest with performance in the Special Judo Fitness Test (SJFT) and whether groups with different RR values at rest show different performance in the SJFT and during post-test recovery. Sixteen judo athletes with 7.2 +/- 3.9 years of training experience participated in the study. Before and after the SJFT execution HRV and lactate measurements were conducted. For HRV analysis, we used the mean interval RR, the standard deviation of the RR interval (SDNN), the root mean square of successive differences in RR intervals (RMSSD), the low frequency (LF) and high frequency (HF) in normalized and absolute units. The sample was split into two groups (low RR and high RR) to verify if this variable could differentiate between specific performance. For the SDNN, a significant and moderate correlation (r = 0.53) was found with the total number of throws and throws in the series A (r = 0.56) and B (r = 0.54) and for the RMSSD a correlation with throws during series B (r = 0.59) in the SJFT. However, the groups did not differ in performance and recovery. Therefore, HRV is related to intermittent judo performance; however, it cannot differentiate between judokas at different levels of performance

Combined Impairments in Vision, Hearing and Cognition are Associated with Greater Levels of Functional and Communication Difficulties Than Cognitive Impairment Alone: Analysis of interRAI Data for Home Care and Long-Term Care Recipients in Ontario

Objectives: The objective of the current study was to understand the added effects of having a sensory impairment (vision and/or hearing impairment) in combination with cognitive impairment with respect to health-related outcomes among older adults (65+ years old) receiving home care or residing in a long-term care (LTC) facility in Ontario, Canada. Methods: Cross-sectional analyses were conducted using existing data collected with one of two interRAI assessments, one for home care (n = 291,824) and one for LTC (n = 110,578). Items in the assessments were used to identify clients with single sensory impairments (e.g., vision only [VI], hearing only [HI]), dual sensory impairment (DSI; i.e., vision and hearing) and those with cognitive impairment (CI). We defined seven mutually exclusive groups based on the presence of single or combined impairments. Results: The rate of people having all three impairments (i.e., CI+DSI) was 21.3% in home care and 29.2% in LTC. Across the seven groups, individuals with all three impairments were the most likely to report loneliness, to have a reduction in social engagement, and to experience reduced independence in their activities of daily living (ADLs) and instrumental ADLs (IADLs). Communication challenges were highly prevalent in this group, at 38.0% in home care and 49.2% in LTC. In both care settings, communication difficulties were more common in the CI+DSI group versus the CI-alone group. Conclusions: The presence of combined sensory and cognitive impairments is high among older adults in these two care settings and having all three impairments is associated with higher rates of negative outcomes than the rates for those having CI alone. There is a rising imperative for all health care professionals to recognize the potential presence of hearing, vision and cognitive impairments in those for whom they provide care, to ensure that basic screening occurs and to use those results to inform care plans

Willingness to pay for quality traits and implications for sweetpotato variety breeding: case of Mozambique

Despite decades of research and dissemination of improved sweetpotato varieties, uptake at scale remains low and envisaged development goals of food security and livelihoods remain elusive. This is despite demonstrated impacts of such technologies in combating food and nutrition insecurity, amidst global challenges like climate change. Growing evidence show that end-user acceptance of improved varieties is critical in the widespread adoption of such varieties, and inclusion of the heterogenous preferences of diverse sets of end-users in the variety development process is therefore critical. With global changes in weather and consumption patterns, end-users are now demanding varieties that are more suitable to their unique consumption needs, production environments, new market demands and have desired processing characteristics. Such dynamics in demand have necessitated rethinking of breeding programs from the traditional focus on agronomic gains such as increase in yields and yield protection, to consideration of more nuanced quality-related traits that appeal to targeted populations. Against this background, this study sets out to explore the decision-making behavior of Mozambican sweetpotato producers in variety selection, and the implicit value placed on different sweetpotato traits, including the often ignored but crucial quality traits. The aim of the study is to identify the economic valuation of such traits and how they are traded off in variety selection decisions, to allow for prioritization in breeding efforts. To achieve this, an exploratory sequential design in a predominantly quantitative mixed-method design was adopted for the study. First, based on the insights from a gender disaggregated qualitative assessment among sweetpotato growers and consumers and in consultation with breeding experts from Mozambique, the most preferred sweetpotato variety traits in the regions of study were established. These traits were then utilized in the design of a choice experiment, implemented among 860 sweetpotato producers spread across four sweetpotato growing regions in the country. Finally, a generalized multinomial logit model was used to estimate implicit economic valuation of each of the considered trait, as well as heterogenous valuation of such traits across gender, education and age of respondent groups. Results from the study show that producers have a high preference for quality-related traits, with preference for Vitamin A being higher than that for drought tolerance, while dry matter content is valued about the same as drought tolerance. While scoring significantly lower than Vitamin A, drought tolerance and dry matter content, other quality-related traits like root size and sweet taste also have significant positive values implying their importance in informing sweetpotato variety choice. In terms of gender heterogeneity, flesh color is highly valued among the women sub-sample. The study identifies Vitamin A, dry matter content, sweet taste, and medium to big root size, as the key preferred quality traits in Mozambique, in that order. The results imply that these quality traits should be pursued as a suite in breeding objectives, in combination with essential agronomic traits such as high yields and drought tolerance, for higher acceptance and demand of improved sweetpotato varieties across the country