An exploration of open coupled-cavity lasers: from exceptional points to dynamics

In optical communications, there is an increase in demand for investigation of multisection laser cavities, which are involved in the development of Photonic Integrated Circuits or PICs. The requirement for such circuits results from, for example, the increase in demand for faster internet devices, which means improving the infrastructure involved. PICs are useful for such advancements as instead of an electrical circuit, these use optical devices such as lasers. Furthermore, these laser cavities are closely interacting or strongly coupled as they are of millimetre to submillimetre scales. Due to the size and complexity of these devices, they are not yet fully understood. Previous work has shown some interesting behaviour with these strongly coupled cavities. For example, the existence of exceptional points, where two modes coalesce, and also the possibility for a laser mode to go below threshold with increasing population inversion in a cavity, all in the steady state. However, for these types of devices, there is currently no full dynamical model that considers the complexity of strongly coupled cavities, with only outgoing light at the boundary of the laser. Thus, the aim of this thesis is to investigate three important areas. The first is to understand the steady state situation further and improve upon what is known already. We introduce a new basis to do this and create a threshold condition, which is used to explore the complexities of coupled cavities. With this, we further address the occurrence of these exceptional points and give a more in-depth insight into the interesting effects that occur. The second area is to introduce a new, elegant approach in solving the electromagnetic field equation for the steady state, while still considering the geometrical features of a multisection laser. We introduce a second formalism for laser equations at threshold, which is shown to be a projection of a loxodromic spiral on a Riemann sphere with the use of Mobius transformations. With this, we investigate the threshold branches of multisection laser devices and discover a different type of exceptional point, where instead, the branches merge rather than modes. Furthermore, this new approach removes the need for unnecessary information while retaining the important physical characteristics to explain a coupled cavity laser. Lastly, a dynamical model that represents a strongly coupled laser with outgoing boundary conditions is introduced by connecting the classical electromagnetic field to the quantum mechanical description for the active medium. We go beyond the steady state by introducing a time-dependent scaling term for the electromagnetic field, which scales with the population inversion equations to provide a physically explained self-consistent set of dynamical equations. This model confirms results seen in the steady state situation. It also expands upon the steady state to show possible dynamical properties which are a result of the close interactions between both cavities, while crucially considering open boundary conditions while using the spatial profile for the active medium

Household food waste disposal behaviour is driven by perceived personal benefits, recycling habits and ability to compost

Households are responsible for a large proportion of total food waste and are an important focal point for addressing food waste disposal issues. Determinants of household food waste minimisation behaviour have been previously explored; however, little is known about the determinants of household food waste disposal behaviour. Several food waste disposal options are available to households, depending on context, with some disposal practices being more sustainable than others. This study applies the food waste hierarchy to household food waste disposal behaviour and identifies three sustainable food waste disposal behaviours (sorting food waste into the green organics bin, reusing food waste for animal feed, and home composting); and three unsustainable behaviours (disposing of food waste in the general waste bin, the recycling bin, and/or the sink). Using data from a survey of 1027 respondents, a fractional multinomial logit model is used to analyse the associations between explanatory variables and sustainable versus unsustainable household food waste disposal behaviour. Having a kitchen caddy is associated with increased sustainable food waste disposal behaviour (higher proportion of food waste diverted to the green bin and composted). Key factors that drive households’ use of kerbside green organics bins are perceived personal costs and benefits, and recycling habits. Importantly, environmental self-identity is positively associated with home composting practices. Factors associated with a higher proportion of food waste disposed of in the general waste bin (unsustainable behaviour) include stronger perceived inconvenience of using the green bin, living in a unit, and having a higher household income. Findings from this study can provide insight into interventions to promote more sustainable household food waste disposal practices.Trang Thi Thu Nguyen, Lenka Malek, Wendy J. Umberger, Patrick J. O, Conno

Scientists publishing research in English from Indonesia: Analysing outcomes of a training intervention to inform institutional action

Margaret Cargill, Patrick O, Connor, Rika Raffiudin, Nampiah Sukarno, Berry Juliandi and Iman Rusman

Fundamental constructs in food parenting practices: a content map to guide future research

Although research shows that “food parenting practices” can impact children’s diet and eating habits, current understanding of the impact of specific practices has been limited by inconsistencies in terminology and definitions. This article represents a critical appraisal of food parenting practices, including clear terminology and definitions, by a working group of content experts. The result of this effort was the development of a content map for future research that presents 3 overarching, higher-order food parenting constructs – coercive control, structure, and autonomy support – as well as specific practice subconstructs. Coercive control includes restriction, pressure to eat, threats and bribes, and using food to control negative emotions. Structure includes rules and limits, limited/guided choices, monitoring, meal- and snacktime routines, modeling, food availability and accessibility, food preparation, and unstructured practices. Autonomy support includes nutrition education, child involvement, encouragement, praise, reasoning, and negotiation. Literature on each construct is reviewed, and directions for future research are offered. Clear terminology and definitions should facilitate cross-study comparisons and minimize conflicting findings resulting from previous discrepancies in construct operationalization

Epigenome-wide SRC-1 mediated gene silencing represses cellular differentiation in advanced breast cancer

Abstract Purpose: Despite the clinical utility of endocrine therapies for estrogen receptor–positive (ER) breast cancer, up to 40% of patients eventually develop resistance, leading to disease progression. The molecular determinants that drive this adaptation to treatment remain poorly understood. Methylome aberrations drive cancer growth yet the functional role and mechanism of these epimutations in drug resistance are poorly elucidated. Experimental Design: Genome-wide multi-omics sequencing approach identified a differentially methylated hub of prodifferentiation genes in endocrine resistant breast cancer patients and cell models. Clinical relevance of the functionally validated methyl-targets was assessed in a cohort of endocrine-treated human breast cancers and patient-derived ex vivo metastatic tumors. Results: Enhanced global hypermethylation was observed in endocrine treatment resistant cells and patient metastasis relative to sensitive parent cells and matched primary breast tumor, respectively. Using paired methylation and transcriptional profiles, we found that SRC-1–dependent alterations in endocrine resistance lead to aberrant hypermethylation that resulted in reduced expression of a set of differentiation genes. Analysis of ER-positive endocrine-treated human breast tumors (n = 669) demonstrated that low expression of this prodifferentiation gene set significantly associated with poor clinical outcome (P = 0.00009). We demonstrate that the reactivation of these genes in vitro and ex vivo reverses the aggressive phenotype. Conclusions: Our work demonstrates that SRC-1-dependent epigenetic remodeling is a ’high level’ regulator of the poorly differentiated state in ER-positive breast cancer. Collectively these data revealed an epigenetic reprograming pathway, whereby concerted differential DNA methylation is potentiated by SRC-1 in the endocrine resistant setting. Clin Cancer Res; 24(15); 3692–703. ©2018 AACR.</jats:p

The AMMA mulid network for aerosol characterization in West Africa

Three ground based portable low power consumption microlidars (MULID) have been built and deployed at three remote sites in Banizoumbou (Niger), Cinzana (Mali) and M'Bour (Senegal) in the framework of the African Monsoon Multidisciplinary Analyses (AMMA) project for the characterization of aerosols optical properties. A description of the instrument and a discussion of the data inversion method, including a careful analysis of measurement uncertainties (systematic and statistical errors) are presented. Some case studies of typical lidar profiles observed over the Banizoumbou site during 2006 are shown and discussed with respect to the AERONET 7-day back-trajectories and the biomass burning emissions from the Combustion Emission database for the AMMA campaign