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Unitarity of the infinite-volume three-particle scattering amplitude arising from a finite-volume formalism
No full textIn a previous publication, two of us derived a relation between the scattering amplitude of three identical bosons, and a real function referred to as the {divergence-free} K matrix and denoted The result arose in the context of a relation between finite-volume energies and , derived to all orders in the perturbative expansion of a generic low-energy effective field theory. In this work we set aside the role of the finite volume and focus on the infinite-volume relation between , satisfies the three-particle unitarity constraint to all orders. Given that is also free of a class of kinematic divergences, the function may provide a useful tool for parametrizing three-body scattering data. Applications include the phenomenological analysis of experimental data (where the connection to the finite volume is irrelevant) as well as calculations in lattice quantum chromodynamics (where the volume plays a key role)
Rebuilding racket on chez scheme (experience report)
No full textWe rebuilt Racket on Chez Scheme, and it works well-as long as we're allowed a few patches to Chez Scheme. DrRacket runs, the Racket distribution can build itself, and nearly all of the core Racket test suite passes. Maintainability and performance of the resulting implementation are good, although some work remains to improve end-to-end performance. The least predictable part of our effort was how big the differences between Racket and Chez Scheme would turn out to be and how we would manage those differences. We expect Racket on Chez Scheme to become the main Racket implementation, and we encourage other language implementers to consider Chez Scheme as a target virtual machine
Polygenic risk for alcohol misuse is moderated by romantic partnerships
No full textBackground and Aims: Previous twin research suggests relationship status can moderate underlying genetic liability towards alcohol misuse. This paper examined: (1) whether genome‐wide polygenic scores (GPS) for alcohol consumption are associated with alcohol misuse; (2) whether these GPS are moderated by romantic relationships (gene–environment interaction; G × E) and (3) whether G × E results are consistent across sex. Design: Linear mixed‐effects models were used to test associations between genome‐wide polygenic scores, relationship status and alcohol use/misuse. Setting: Finnish twins born between 1983 and 1987 identified through Finland's central population registry. Participants: An intensively studied subset of Finnish Twin Study (FinnTwin12) during the young adult phase (aged 20–26 years). The analytical sample includes those with complete interview and genetic data (n = 1201). Measurements: Key measurements included involvement in a romantic partnership, drinking frequency, intoxication frequency and DSM‐IV alcohol dependence (AD) symptoms. Genome‐wide polygenic scores (GPS) were created from available summary statistics from a large genome‐wide association study (GWAS) of drinks per week. Results: GPS predicted drinking frequency [b = 0.109; 95% confidence interval (CI) = 0.050, 0.168], intoxication frequency (b = 0.111; 95% CI = 0.054, 0.168) and AD symptoms (b = 0.123; 95% CI = 0.064, 0.182). Having a romantic relationship negatively influenced the association between GPS and drinking frequency (b = −0.105; 95% CI = −0.211, −0.001), intoxication frequency (b = −0.118; 95% CI = −0.220, −0.016) and AD symptoms (b = −0.119; 95% CI = −0.229, −0.009). There was a three‐way interaction between sex, relationship status and GPS for intoxication frequency (b = 0.223; 95% CI = 0.013, 0.433), such that the reduced association between GPS and intoxication frequency for those in a relationship was only apparent in males. We found no evidence of three‐way interactions for drinking frequency or AD symptoms. Conclusions: Being in a romantic relationship reduced the association between genetic predisposition and drinking, high‐risk drinking and alcohol problems. However, for high‐risk drinking the protective effect was limited to males, mapping onto earlier findings suggesting that males benefit more from romantic partnerships
Drosophila Heterochromatin Stabilization Requires the Zinc-Finger Protein Small Ovary
No full textHeterochromatin-mediated repression is essential for controlling the expression of transposons and for coordinated cell type-specific gene regulation. The small ovary (sov) locus was identified in a screen for female-sterile mutations in Drosophila melanogaster, and mutants show dramatic ovarian morphogenesis defects. We show that the null sov phenotype is lethal and map the locus to the uncharacterized gene CG14438, which encodes a nuclear zinc-finger protein that colocalizes with the essential Heterochromatin Protein 1 (HP1a). We demonstrate Sov functions to repress inappropriate gene expression in the ovary, silence transposons, and suppress position-effect variegation in the eye, suggesting a central role in heterochromatin stabilization
Walking pace and the risk of stroke: a meta-analysis of prospective cohort studies
No full textPurpose: The extent to which walking pace is associated with a reduced risk for stroke remains unclear. This study examined the association between walking pace and stroke risk based on prospective cohort studies. Methods: Databases of PubMed, EMBASE, Web of Science, Scopus, and China National Knowledge Internet were searched from the inception dates to January 31, 2019, for prospective cohort studies focusing on walking pace and risk of stroke in adults. Two reviewers independently extracted data and assessed the quality of the studies. The dependent measure was stroke incidence. Using random-effects models, a meta-analysis was performed to estimate the overall relative risks (RR) of stroke incidence and 95% confidence intervals (CIs) for the individuals with the fastest walking paces vs. individuals with the slowest walking paces. A dose-response relationship was also examined. Results: After screening 1294 titles/abstracts and 14 full-text studies identified in the search, 7 studies (from 8 cohorts) were included in the meta-analysis. The 7 studies included a total of 135,645 participants (95.2% women; mean age 63.6 years) and 2229 stroke events (median follow-up time = 8.0 years). Compared to individuals in the slowest walking-pace category (median = 1.6 km/h), individuals in the fastest walking-pace category (median = 5.6 km/h) had a 44% lower risk of stroke (pooled RR = 0.56, 95%CI: 0.48–0.65). There was also a linear dose-response relationship (RR = 0.87; 95%CI: 0.83–0.91), with the risk of stroke decreased by 13% for every 1 km/h increment in baseline walking pace. We observed similar results across walking-pace assessment, type of stroke ascertainment, stroke subtypes, sex, sample size, and duration of follow-up. Conclusion: Findings from this meta-analysis indicate that walking pace is inversely associated with the risk of stroke
Tissue-specific expression profiles and positive selection analysis in the tree swallow (Tachycineta bicolor) using a de novo transcriptome assembly
No full textTree swallows (Tachycineta bicolor) are one of the most commonly studied wild birds in North America. They have advanced numerous research areas, including life history, physiology, and organismal responses to global change; however, transcriptomic resources are scarce. To further advance the utility of this system for biologists across disciplines, we generated a transcriptome for the tree swallow using six tissues (brain, blood, ovary, spleen, liver, and muscle) collected from breeding females. We de novo assembled 207,739 transcripts, which we aligned to 14,717 high confidence protein-coding genes. We then characterized each tissue with regard to its unique genes and processes and applied this transcriptome to two fundamental questions in evolutionary biology and endocrinology. First, we analyzed 3,015 single-copy orthologs and identified 46 genes under positive selection in the tree swallow lineage, including those with putative links to adaptations in this species. Second, we analyzed tissue-specific expression patterns of genes involved in sex steroidogenesis and processing. Enzymes capable of synthesizing these behaviorally relevant hormones were largely limited to the ovary, whereas steroid binding genes were found in nearly all other tissues, highlighting the potential for local regulation of sex steroid-mediated traits. These analyses provide new insights into potential sources of phenotypic variation in a free-living female bird and advance our understanding of fundamental questions in evolutionary and organismal biology
Arthur Conan Doyle's Americanisms
Full text linkArthur Conan Doyle wrote about America and Americans throughout his career, beginning with his second published story, ‘The American’s Tale.’ Thick with Americanisms, ‘The American’s Tale’ includes some rare lexical items, one of them missing from the dictionary record, that lead us to likely sources. A Study in Scarlet and The Valley of Fear also depend on a profusion of Americanisms for the sake of authenticity in their American settings. Conan Doyle’s Americanisms, however, matter beyond cultural ‘flavour.’ In later works, they distinguish informal, lower prestige American speech and culture from formal, higher prestige British speech and culture, and thus help to construct an argument of two cultures on narratological terms
A Layered Mounting Method for Extended Time-Lapse Confocal Microscopy of Whole Zebrafish Embryos
Full text linkDynamics of development can be followed by confocal time-lapse microscopy of live transgenic zebrafish embryos expressing fluorescence in specific tissues or cells. A difficulty with imaging whole embryo development is that zebrafish embryos grow substantially in length. When mounted as regularly done in 0.3-1% low melt agarose, the agarose imposes growth restriction, leading to distortions in the soft embryo body. Yet, to perform confocal time-lapse microscopy, the embryo must be immobilized. This article describes a layered mounting method for zebrafish embryos that restrict the motility of the embryos while allowing for the unrestricted growth. The mounting is performed in layers of agarose at different concentrations. To demonstrate the usability of this method, whole embryo vascular, neuronal and muscle development was imaged in transgenic fish for 55 consecutive hours. This mounting method can be used for easy, low-cost imaging of whole zebrafish embryos using inverted microscopes without requirements of molds or special equipment
Closing Thoughts on "Information Systems Research: Thinking Outside the Basket and Beyond the Journal"
Full text linkThis essay provides a rejoinder by the original authors to the set of responses to Fitzgerald, B., Dennis, A. R., An, J., Tsutsui, S., & Muchala, R. C. (2019). Information systems research: Thinking outside the basket and beyond the journal. Communications of the Association for Information Systems, 45, 110-133
