Publications by authors named "Sigurdhur Kristjansson"

Study Question: Does the risk of childhood cancer following ARTs vary by sex?

Summary Answer: In this registry-based study, some childhood cancers showed positive sex- and age-specific associations in children conceived using certain ART modalities, which were not evident in overall combined analyses.

What Is Known Already: The relationship between ART and risk of childhood cancer has shown diverse outcomes in prior research. Studies examining whether there are sex differences in childhood cancer risk after ART conception are lacking.

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Aim: To evaluate whether extremely preterm infants with considerable gastrointestinal (GI) symptoms during the neonatal period, but without major abdominal surgery or necrotising enterocolitis, had an increased probability of developing GI dysfunction later in life.

Methods: A retrospective, case-control study on extremely preterm neonates that underwent an upper gastrointestinal contrast series (UGI) between 2012 and 2017, with UGI used as a marker of considerable GI symptoms. Controls were matched for sex and gestational age.

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Large-scale communication networks, such as the Internet, rely on routing packets of data through multiple intermediate nodes to transmit information from a sender to a receiver. In this paper, we develop a model of a quantum communication network that routes information simultaneously along multiple paths passing through intermediate stations. We demonstrate that a quantum routing approach can in principle extend the distance over which information can be transmitted reliably.

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In two experiments, we explored whether cross-modal cues can be used to improve foraging for multiple targets in a novel human foraging paradigm. Foraging arrays consisted of a 6 × 6 grid containing outline circles with a small dot on the circumference. Each dot rotated from a random starting location in steps of 30°, either clockwise or counterclockwise, around the circumference.

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Background: Adolescent violence in the United States is a prevalent public health problem and is understudied in rural settings. Anger is a significant risk factor for adolescent violence. To better craft adolescent violence interventions, it is important to examine anger and identify its most significant associated factors.

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Objective: Endometriosis affects 10% of women worldwide and is linked to adverse pregnancy outcomes, including preterm birth. Recent epidemiological and genetic studies indicate that endometriosis may influence gestational duration and the likelihood of preterm birth. This study aimed to estimate the direct genetic causal effects of endometriosis on gestational duration and preterm birth using Mendelian randomisation (MR) analysis, leveraging genetic data from recent genome-wide association studies (GWASs).

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Virtue-based ethics prioritizes phronesis (practical wisdom) because, as rules have become less action-guiding, good judgment (phronesis) becomes more necessary as a guiding meta-virtue. The view of phronesis that MacIntyre proposed in After Virtue (hereafter, AV phronesis) has been applied in medical ethics despite his substantial deviations from his source (Aristotle) in After Virtue. In this paper, we clarify the differences between the neo-Aristotelian and AV phronesis views and argue for a neo-Aristotelian phronesis with four functions (constitutive, adjudicative, emotion regulative, and blueprint).

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While previous foraging studies have identified key variables that determine attentional selection, they are affected by the global statistics of the tasks. In most studies, targets are selected one at a time without replacement while distractor numbers remain constant, steadily reducing the ratios of targets to distractors with every selection. We designed a foraging task with a sequence of local "snapshots" of foraging displays, with each snapshot requiring a target selection.

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While the visual world is rich and complex, importantly, it nevertheless contains many statistical regularities. For example, environmental feature distributions tend to remain relatively stable from one moment to the next. Recent findings have shown how observers can learn surprising details of environmental color distributions, even when the colors belong to actively ignored stimuli such as distractors in visual search.

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Article Synopsis
  • - The study evaluated the experiences of stakeholders involved in the Integrated Community Engagement (ICE) Collaborative, which focuses on preventing adolescent substance use in rural West Virginia, after three years of implementation.
  • - Guided by the Icelandic Prevention Model (IPM), ICE aims to foster collaboration between various community members and shift from short-term funding for programs to a sustainable, long-term approach led by local practitioners.
  • - Qualitative interviews with 33 stakeholders revealed six key themes, highlighting the importance of community involvement, outreach, program accessibility, addressing funding issues, considering family contexts, and promoting constructive conversations about strategies for prevention.
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Developmental trajectories for neck disability after whiplash injury have been identified. Their relationship to cold and mechanical sensitivity trajectories is not known. We aimed to (1) identify recovery trajectories of cold and mechanical sensitivity, (2) explore their codevelopment with disability trajectories, (3) identify predictors of sensitivity trajectories, and (4) explore codevelopment of cold and mechanical sensitivity trajectories.

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Previous studies have shown cord-blood DNA methylation differences in newborns conceived using assisted reproductive technologies (ART) compared to those conceived naturally. However, whether these ART-related DNA methylation differences vary with children's sex is unknown. We hypothesize that the DNA methylation differences in cord blood between ART-conceived and naturally conceived newborns also varies by the sex of the child, with distinct patterns of differential methylation present in males and females.

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Study Objectives: To assess whether the frequency content of electroencephalography (EEG) and electrooculography (EOG) during nocturnal polysomnography (PSG) can predict all-cause mortality.

Methods: Power spectra from PSGs of 8,716 participants, included from the MrOS Sleep Study and the Sleep Heart Health Study (SHHS), were analyzed in deep learning-based survival models. The best-performing model was further examined using SHapley Additive Explanation (SHAP) for data-driven sleep-stage specific definitions of power bands, which were evaluated in predicting mortality using Cox Proportional Hazards models.

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A central goal in evolutionary biology is to understand how different evolutionary processes cause trait change in wild populations. However, quantifying evolutionary change in the wild requires linking trait change to shifts in allele frequencies at causal loci. Nevertheless, datasets that allow for such tests are extremely rare and existing theoretical approaches poorly account for the evolutionary dynamics that likely occur in ecological settings.

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Background: The Icelandic horse and Exmoor pony are ancient, native breeds, adapted to harsh environmental conditions and they have both undergone severe historic bottlenecks. However, in modern days, the selection pressures on these breeds differ substantially. The aim of this study was to assess genetic diversity in both breeds through expected (H) and observed heterozygosity (H) and effective population size (Ne).

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Introduction: Caffeine is a psychostimulant possessing arousal, motor activation, and reinforcing properties, which is consumed daily by most adolescents aged 12-19 years. Although current understanding of the implications of adolescent caffeine consumption for school behaviors remains incomplete, studies have shown that in addition to acute effects of the drug, in common with other habit-forming psychoactive substances, regular use leads to physical dependence, evidenced by recurring negative withdrawal symptoms.

Methods: Employing two waves of longitudinal data, we tested the prospective association between daily caffeine use and homeroom teacher-observed self-control and problem behavior in a sample of middle-school students in 20 schools in West Virginia in the United States.

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This paper explores the decline in adolescent mental health and the weakening of traditional moral frameworks, positing education in the virtues as protective of mental health due to the intrinsic link between moral/existential wellbeing and psychological health. By integrating character education into school curricula, a continuous "dosage" of moral guidance may be an optimal way to ensure a gradual and ever-clearer articulation of a life worth living and how to live well. The paper critiques popular clinical and positive psychological approaches to promoting wellbeing, which often miss the existential and moral dimensions of adolescent growth.

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This article is about a virtue ethical approach to the professional ethics of teaching, centred around the ideal of (practical wisdom) in an Aristotelian sense. It is grounded empirically in extensive research conducted at the Jubilee Centre for Character and Virtues into teachers and other UK professionals, and it is grounded theoretically in recent efforts to revive an Aristotelian concept of as excellence in ethical decision-making. The article argues for the need for a virtue-based approach to professional practice, based on time-honoured Aristotelian assumptions and culminating in a conceptually viable construct of as a psycho-moral integrator and adjudicator.

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Background: The school climate concept has been promising, but has long-standing critiques that have not been adequately addressed to date. The School as a Protective Factor approach represents one attempt to offer a new approach that builds on and extends beyond the concept of school climate while addressing previously identified limitations.

Contributions To Theory: The School as a Protective Factor approach offers a new framework for conceptualizing, measuring, and establishing protective school social and learning environments that co-promote academic achievement and student health in schools, especially student mental health and substance use/abuse prevention.

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Background: The conceptual framework for School as a Protective Factor approach was presented in a companion article in this issue of the journal. The current article describes the validation of the School as a Protective Factor-Brief (SPF-Brief), a 13-item survey measuring the 3 core constructs and 13 defining characteristics of this framework.

Methods: The SPF-Brief was validated through 2 studies.

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Article Synopsis
  • Biodiversity in ecosystems, especially in unique environments like groundwater-filled lava caves, results from both neutral and niche-based factors, with ongoing debate among scientists about their relative importance.
  • In a study of invertebrate communities in these caves, researchers found that while the epibenthic community might be shaped by neutral processes, the benthic community showed clear relationships with ecological factors like energy availability and pH, indicating a role for niche-based processes.
  • The findings highlight the necessity of considering both neutral and niche-based processes when studying biodiversity in freshwater ecosystems, which are increasingly vulnerable to environmental changes.
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Background: High-income countries offer social assistance (welfare) programs to help alleviate poverty for people with little or no income. These programs have become increasingly conditional and stringent in recent decades based on the premise that transitioning people from government support to paid work will improve their circumstances. However, many people end up with low-paying and precarious jobs that may cause more poverty because they lose benefits such as housing subsidies and health and dental insurance, while incurring job-related expenses.

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The Icelandic Prevention Model (IPM) follows a systematic but flexible process of community capacity building, data collection, analysis, dissemination, and community-engaged decision-making to guide the data-informed selection, prioritization, and implementation of intervention strategies in preventing adolescent substance use. This paper describes two new evaluation tools intended to assess the: 1) integrity of IPM implementation, and 2) unique aspects of IPM implementation in different community contexts. These evaluation tools include a: 1) five-phase IPM Evaluation Framework for Assessing Value Across Communities, Cultures, and Outcomes (IPM-EF); and 2) 10-Step IPM Implementation Integrity and Consistency Assessment (IPM-IICA) that utilizes both quantitative (scored) and qualitative (narrative) data elements to characterize implementation integrity and consistency at both community coalition and school community levels.

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