Parametric downconversion with optimized spectral properties in nonlinear photonic crystals

We study the joint spectral properties of photon pairs generated by spontaneous parametric down-conversion in a one-dimensional nonlinear photonic crystal in a collinear, degenerate, type-II geometry. We show that the photonic crystal properties may be exploited to compensate for material dispersion and obtain photon pairs that are nearly factorable, in principle, for arbitrary materials and spectral regions, limited by the ability to fabricate the nonlinear crystal with the required periodic variation in the refractive indices for the ordinary and extraordinary waves.Comment: 9 pages, 6 figure

Gravity is not a Pairwise Local Classical Channel

It is currently believed that there is no experimental evidence on possibly quantum features of gravity or gravity-motivated modifications of quantum mechanics. Here we show that single-atom interference experi- ments achieving large spatial superpositions can rule out a framework where the Newtonian gravitational inter- action is fundamentally classical in the information-theoretic sense: it cannot convey entanglement. Specifically, in this framework gravity acts pairwise between massive particles as classical channels, which effectively induce approximately Newtonian forces between the masses. The experiments indicate that if gravity does reduce to the pairwise Newtonian interaction between atoms at the low energies, this interaction cannot arise from the exchange of just classical information, and in principle has the capacity to create entanglement. We clarify that, contrary to current belief, the classical-channel description of gravity differs from the model of Diosi and Penrose, which is not constrained by the same data.Comment: 13 pages, 5 figures, 2 tables, Late

Visual word recognition in bilinguals and monolinguals: behavioural and ERP investigations of the role of word frequency, lexicality and repetition

This thesis investigated visual word recognition in bilinguals and monolinguals through the effects of word frequency, lexicality and repetition. The first series of experiments focused on whether bilinguals can suppress lexical access in a non-target language and the role of task demands in L1 and L2 lexical access. The next series of experiments further investigated the role of task demands, list composition and repetition in monolinguals. The ERP data show, for the first time, that in bilinguals, lexical access occurs in the non-target language, supporting the notion of a nonselective lexical access. Delayed lexicality effects in ERPs for L2 compared to L1 suggested a delay in lexical access for L2 in late bilinguals, although behavioural data showed a similar word frequency effect to L1. These conflicting responses have not been anticipated by current models of bilingual visual word recognition. However, monolingual data make clear that lexical effects can be modulated by task demands and list composition in behavioural responses. In monolinguals, the slower processing of less familiar items was enhanced by item repetition only when the task required a lexical decision and words and word-like letter strings were presented. Lastly, this thesis has demonstrated that current models of visual word recognition have not fully implemented these elements and have not predicted response times distribution or ERPs. Future models of visual word recognition should incorporate these elements to be able to characterise lexical access in bilinguals and monolinguals

Experiences of Latina First Generation College Students: Exploring Resources Supporting the Balancing of Academic Pursuits and Family Life

This study used a qualitative interview approach and thematic analysis (Braune and Clark, 2006) to interview first generation college student Latinas, exploring their experiences with higher education, their navigation/negotiation of resources for academic success and for wellness of self and family, and barriers they face as they attempt to both safeguard self and family wellness and reach their academic goals. It also directly explored the potential resources participants would find useful and ways in which colleges/universities might support them in these pursuits. With this method, this study identified 6 major themes in the lives of first generation college student Latinas: 1) Contextual stressors / systemic disadvantage, involving the tendency for participants to be at a disadvantage within higher education than mainstream society, including participant\u27s being the targets of racism/negative stereotypes, complications related to documentation concerns, their need to navigate the college environment without a map, their family\u27s limited understanding of higher education, their need to carry a heavy work load, and their need to attend to family obligations; 2) education as an obligation to family-motivation, involving participant\u27s tendency to think of a college education as the passport to family socioeconomic mobility and wellness, as a way to repay their parents for their sacrifices, and as a way to complete a goal their mothers started but were unable to finish; 3) the chosen one/to be a role model- motivation, involving the tendency for participants to hold a sense of responsibility to live up to high expectations as the first in their families to enter college, to break negative stereotypes about Latinas and higher education, and to serve as positive role models to their family, community, and their own children; 4) Children, present and future, involving the tendency for participants with parental obligations to place these obligations above all else and to identify their children as a principal source of motivation, and the tendency for participants to postpone having children until after they achieve their academic goals; 5) impact of important encounters, involving participants\u27 tendency to identify positive and negative encounters they experienced as important in their development and in the balancing of family and educational goals, to identify the importance of influences of external cultures in their educational trajectory, and to voice a need for mentorship in higher education; and 6) inner strengths and goals, involving the tendency for participants to turn to their faith for spiritual support and turn to their church for social support and as a source of trustworthy help, and identify personal qualities they experienced as sources of strength, including Paciencia (patience), Perseverancia (perseverance), orgullo (Pride), rebeldia (rebelliousness/defiance), and sacrificio (ability to sacrifice). These conclusions highlight the ways that, for the Latinas interviewed, education is thought of in intergenerational terms, where there are legacies of the past and future. Participants expressed an understanding of what they owe their families, and also consider what they will be able to offer their children and how they might contribute to their family\u27s future

Integration of disease-specific single nucleotide polymorphisms, expression quantitative trait loci and coexpression networks reveal novel candidate genes for type 2 diabetes.

Aims/hypothesisWhile genome-wide association studies (GWASs) have been successful in identifying novel variants associated with various diseases, it has been much more difficult to determine the biological mechanisms underlying these associations. Expression quantitative trait loci (eQTL) provide another dimension to these data by associating single nucleotide polymorphisms (SNPs) with gene expression. We hypothesised that integrating SNPs known to be associated with type 2 diabetes with eQTLs and coexpression networks would enable the discovery of novel candidate genes for type 2 diabetes.MethodsWe selected 32 SNPs associated with type 2 diabetes in two or more independent GWASs. We used previously described eQTLs mapped from genotype and gene expression data collected from 1,008 morbidly obese patients to find genes with expression associated with these SNPs. We linked these genes to coexpression modules, and ranked the other genes in these modules using an inverse sum score.ResultsWe found 62 genes with expression associated with type 2 diabetes SNPs. We validated our method by linking highly ranked genes in the coexpression modules back to SNPs through a combined eQTL dataset. We showed that the eQTLs highlighted by this method are significantly enriched for association with type 2 diabetes in data from the Wellcome Trust Case Control Consortium (WTCCC, p = 0.026) and the Gene Environment Association Studies (GENEVA, p = 0.042), validating our approach. Many of the highly ranked genes are also involved in the regulation or metabolism of insulin, glucose or lipids.Conclusions/interpretationWe have devised a novel method, involving the integration of datasets of different modalities, to discover novel candidate genes for type 2 diabetes

Visual word recognition in bilinguals and monolinguals: behavioural and ERP investigations of the role of word frequency, lexicality and repetition

This thesis investigated visual word recognition in bilinguals and monolinguals through the effects of word frequency, lexicality and repetition. The first series of experiments focused on whether bilinguals can suppress lexical access in a non-target language and the role of task demands in L1 and L2 lexical access. The next series of experiments further investigated the role of task demands, list composition and repetition in monolinguals. The ERP data show, for the first time, that in bilinguals, lexical access occurs in the non-target language, supporting the notion of a nonselective lexical access. Delayed lexicality effects in ERPs for L2 compared to L1 suggested a delay in lexical access for L2 in late bilinguals, although behavioural data showed a similar word frequency effect to L1. These conflicting responses have not been anticipated by current models of bilingual visual word recognition. However, monolingual data make clear that lexical effects can be modulated by task demands and list composition in behavioural responses. In monolinguals, the slower processing of less familiar items was enhanced by item repetition only when the task required a lexical decision and words and word-like letter strings were presented. Lastly, this thesis has demonstrated that current models of visual word recognition have not fully implemented these elements and have not predicted response times distribution or ERPs. Future models of visual word recognition should incorporate these elements to be able to characterise lexical access in bilinguals and monolinguals

Life cycle sustainability assessment of non-beverage bottles made of recycled High Density Polyethylene

The current plastic industry is associated with climate change, fossil fuel depletion and littering of plastic waste. To reduce these environmental impacts, companies and governmental bodies are increasingly adopting strategies based on the concept Circular Economy. However, circular decision-making is usually based on analyses that do not provide enough insights in every sustainability dimension, risking burden-shifting. In this study, environmental, economic and social life cycle assessment (LCA) techniques have been integrated into an overarching sustainability life cycle assessment (LCSA) to assess the impact of recycling High Density Polyethylene (HDPE) non-beverage bottles. The study assesses the impact in 11 environmental categories, the life cycle costs, and the social risks associated with the related economic sectors. An ad-hoc system expansion approach was developed to overcome the multifunctionality issue so commonly challenging in circular systems. The results indicate that using recycled HDPE leads to significant reductions in all the considered environmental categories. The economic analysis indicated that the material cost of recycled HDPE is slightly lower than for virgin HDPE, but the manufacturing costs are higher and highly dependent on the specific value chain. The social risks of recycling were found to be higher than for virgin plastic production, and mainly occurring outside the country where the recycling takes place (The Netherlands). Nevertheless, this analysis presents high uncertainty due to the heterogeneity in the recycling sector of the database. This study shows how the LCSA approach can be used to assess and compare the impacts and benefits of circular strategies and calls for further efforts to develop higher disaggregated social risk databases

A food and beverage map: Exploring food-beverage pairing through projective mapping

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