286 research outputs found

    Modular Invariance of Finite Size Corrections and a Vortex Critical Phase

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    We analyze a continuous spin Gaussian model on a toroidal triangular lattice with periods L0L_0 and L1L_1 where the spins carry a representation of the fundamental group of the torus labeled by phases u0u_0 and u1u_1. We find the {\it exact finite size and lattice corrections}, to the partition function ZZ, for arbitrary mass mm and phases uiu_i. Summing Z1/2Z^{-1/2} over phases gives the corresponding result for the Ising model. The limits m0m\rightarrow0 and ui0u_i\rightarrow0 do not commute. With m=0m=0 the model exhibits a {\it vortex critical phase} when at least one of the uiu_i is non-zero. In the continuum or scaling limit, for arbitrary mm, the finite size corrections to lnZ-\ln Z are {\it modular invariant} and for the critical phase are given by elliptic theta functions. In the cylinder limit L1L_1\rightarrow\infty the ``cylinder charge'' c(u0,m2L02)c(u_0,m^2L_0^2) is a non-monotonic function of mm that ranges from 2(1+6u0(u01))2(1+6u_0(u_0-1)) for m=0m=0 to zero for mm\rightarrow\infty.Comment: 12 pages of Plain TeX with two postscript figure insertions called torusfg1.ps and torusfg2.ps which can be obtained upon request from [email protected]

    Recent Trends in Local-Scale Marine Biodiversity Reflect Community Structure and Human Impacts

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    The modern biodiversity crisis reflects global extinctions and local introductions. Human activities have dramatically altered rates and scales of processes that regulate biodiversity at local scales [1-7]. Reconciling the threat of global biodiversity loss [2, 4, 6-9] with recent evidence of stability at fine spatial scales [10,11] is a major challenge and requires a nuanced approach to biodiversity change that integrates ecological understanding. With a new dataset of 471 diversity time series spanning from 1962 to 2015 from marine coastal ecosystems, we tested (1) whether biodiversity changed at local scales in recent decades, and (2) whether we can ignore ecological context (e.g., proximate human impacts, trophic level, spatial scale) and still make informative inferences regarding local change. We detected a predominant signal of increasing species richness in coastal systems since 1962 in our dataset, though net species loss was associated with localized effects of anthropogenic impacts. Our geographically extensive dataset is unlikely to be a random sample of marine coastal habitats; impacted sites (3% of our time series) were underrepresented relative to their global presence. These local-scale patterns do not contradict the prospect of accelerating global extinctions [2,4,6-9] but are consistent with local species loss in areas with direct human impacts and increases in diversity due to invasions and range expansions in lower impact areas. Attempts to detect and understand local biodiversity trends are incomplete without information on local human activities and ecological context

    Pain in the Past and Pleasure in the Future : The Development of Past-Future Preferences for Hedonic Goods

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    It seems self-evident that people prefer painful experiences to be in the past and pleasurable experiences to lie in the future. Indeed, it has been claimed that, for hedonic goods, this preference is absolute (Sullivan, 2018). Yet very little is known about the extent to which people demonstrate explicit preferences regarding the temporal location of hedonic experiences, about the developmental trajectory of such preferences, and about whether such preferences are impervious to differences in the quantity of envisaged past and future pain or pleasure. We find consistent evidence that, all else being equal, adults and children aged 7 and over prefer pleasure to lie in the future and pain in the past and believe that other people will too. They also predict that other people will be happier when pleasure is in the future rather than the past but sadder when pain is the future rather than the past. Younger children have the same temporal preferences as adults for their own painful experiences, but prefer their pleasure to lie in the past, and do not predict that others’ levels of happiness or sadness vary dependent on whether experiences lie in the past or the future. However, from the age of 7, temporal preferences were typically abandoned at the earliest opportunity when the quantity of past pain or pleasure was greater than the quantity located in the future. Past-future preferences for hedonic goods emerge early developmentally but are surprisingly flexible

    Translation initiation downstream from annotated start codons in human mRNAs coevolves with the Kozak context

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    Eukaryotic translation initiation involves preinitiation ribosomal complex 5′ -to-3′ directional probing of mRNA for codons suitable for starting protein synthesis. The recognition of codons as starts depends on the codon identity and on its immediate nucleotide context known as Kozak context. When the context is weak (i.e., nonoptimal), leaky scanning takes place during which a fraction of ribosomes continues the mRNA probing. We explored the relationship between the context of AUG codons annotated as starts of protein-coding sequences and the next AUG codon occurrence. We found that AUG codons downstream from weak starts occur in the same frame more frequently than downstream from strong starts. We suggest that evolutionary selection on in-frame AUGs downstream from weak start codons is driven by the advantage of the reduction of wasteful out-of-frame product synthesis and also by the advantage of producing multiple proteoforms from certain mRNAs. We confirmed translation initiation downstream from weak start codons using ribosome profiling data. We also tested translation of alternative start codons in 10 specific human genes using reporter constructs. In all tested cases, initiation at downstream start codons was more productive than at the annotated ones. In most cases, optimization of Kozak context did not completely abolish downstream initiation, and in the specific example of CMPK1 mRNA, the optimized start remained unproductive. Collectively, our work reveals previously uncharacterized forces shaping the evolution of protein-coding genes and points to the plurality of translation initiation and the existence of sequence features influencing start codon selection, other than Kozak context.Russian Science Foundation (RSF) 20-14-00121Science Foundation Ireland 210692/Z/18/ZScience Foundation Ireland 12/RC/2276_P2Erasmus+ ProgrammePlan Propio de Investigacion 2019 de la Universidad de GranadaMinistry of Economy of Spain DPI2017-84439-REuropean Union (EU) DPI2017-84439-

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

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    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

    Analysis of detector performance in a gigahertz clock rate quantum key distribution system

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    We present a detailed analysis of a gigahertz clock rate environmentally robust phase-encoded quantum key distribution (QKD) system utilizing several different single-photon detectors, including the first implementation of an experimental resonant cavity thin-junction silicon single-photon avalanche diode. The system operates at a wavelength of 850 nm using standard telecommunications optical fibre. A general-purpose theoretical model for the performance of QKD systems is presented with reference to these experimental results before predictions are made about realistic detector developments in this system. We discuss, with reference to the theoretical model, how detector operating parameters can be further optimized to maximize key exchange rates

    Variation in diabetes care by age: opportunities for customization of care

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    BACKGROUND: The quality of diabetes care provided to older adults has usually been judged to be poor, but few data provide direct comparison to other age groups. In this study, we hypothesized that adults age 65 and over receive lower quality diabetes care than adults age 45–64 years old. METHODS: We conducted a cohort study of members of a health plan cared for by multiple medical groups in Minnesota. Study subjects were a random sample of 1109 adults age 45 and over with an established diagnosis of diabetes using a diabetes identification method with estimated sensitivity 0.91 and positive predictive value 0.94. Survey data (response rate 86.2%) and administrative databases were used to assess diabetes severity, glycemic control, quality of life, microvascular and macrovascular risks and complications, preventive care, utilization, and perceptions of diabetes. RESULTS: Compared to those aged 45–64 years (N = 627), those 65 and older (N = 482) had better glycemic control, better health-related behaviors, and perceived less adverse impacts of diabetes on their quality of life despite longer duration of diabetes and a prevalence of cardiovascular disease twice that of younger patients. Older patients did not ascribe heart disease to their diabetes. Younger adults often had explanatory models of diabetes that interfere with effective and aggressive care, and accessed care less frequently. Overall, only 37% of patients were simultaneously up-to-date on eye exams, foot exams, and glycated hemoglobin (A1c) tests within one year. CONCLUSION: These data demonstrate the need for further improvement in diabetes care for all patients, and suggest that customisation of care based on age and explanatory models of diabetes may be an improvement strategy that merits further evaluation
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