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Biologists aim to explain patterns of growth, reproduction, and ageing that characterize life histories, yet we are just beginning to understand the proximate mechanisms that generate this diversity. Existing research in this area has focused on telomeres but has generally overlooked the telomere’s most direct mediator, the shelterin protein complex. Shelterin proteins physically interact with the telomere to shape its shortening and repair. They also regulate metabolism and immune function, suggesting a potential role in life history variation in the wild. However, research on shelterin proteins is uncommon outside of biomolecular work. Intraspecific analyses can play an important role in resolving these unknowns because they reveal subtle variation in life history within and among populations. Here, we assessed ecogeographic variation in shelterin protein abundance across eight populations of tree swallow (Tachycineta bicolor) with previously documented variation in environmental and life history traits. Using blood gene expression of four shelterin proteins in 12-day old nestlings, we tested the hypothesis that shelterin protein gene expression varies latitudinally and in relation to both telomere length and life history. Shelterin protein gene expression differed among populations and tracked non-linear variation in latitude: nestlings from mid-latitudes expressed nearly double the shelterin mRNA on average than those at more northern and southern sites. However, telomere length was not significantly related to latitude. We next assessed whether telomere length and shelterin protein gene expression correlate with 12-day old body mass and wing length, two proxies of nestling growth linked to future fecundity and survival. We found that body mass and wing length correlated more strongly (and significantly) with shelterin protein gene expression than with telomere length. These results highlight telomere regulatory shelterin proteins as potential mediators of life history variation among populations. Together with existing research linking shelterin proteins and life history variation within populations, these ecogeographic patterns underscore the need for continued integration of ecology, evolution, and telomere biology, which together will advance understanding of the drivers of life history variation in nature. 

Problem-based learning (PBL) is gaining momentum in engineering education as a student-centered teaching approach that engages students in problems that mirror realities of practice. While the goal of this pedagogical approach is to more authentically prepare and train students for success in the field, it can be both challenging and frustrating for faculty to effectively implement. In this research paper, the opinions of faculty experts from aerospace engineering and PBL are considered. Data were collected through two structured focus groups to identify areas deemed critical for the transition of an introductory, second-year aerospace engineering course to PBL at an R1 university on the East Coast of the United States. Four different dimensions of PBL integration were considered: design, learning objectives, implementation/facilitation, and assessment. Through a thematic analysis of focus group transcripts, results showed that while the experts identified many areas that were critical to consider during this transition, there are important areas of divergence among the expert groups. In fact, areas of distinct opposition were exposed. This study highlights the importance of considering feedback from both content/technical experts and pedagogical design experts during the development and integration of PBL and lays the groundwork for further exploration of if and how consensus between these two groups can be found to support improved curriculum development. 

This full paper is focused on research into how educators might use concept mapping to explore and design learning experiences in a problem-based learning environment. Attempts to incorporate more open-ended, ill-structured experiences have increased but are challenging for faculty to implement because there are no systematic methods or approaches that support the educator in designing these learning experiences. In the reported work, we present an exploratory study toward a systematic approach for comparing and manipulating problems. The approach combines concept mapping with Jonassen’s characterization of problems and the forms of knowledge required to solve them. We explore manipulation pathways for a problem that can be pursued by an instructor who is interested in impacting the dimensions of structuredness and complexity. We compare similarities and differences among two problems taken from introductory aerospace engineering courses. We consider manipulation of structuredness and complexity and the change propagation in forms of knowledge and solution pathways. 

Introduction: The work reported here subscribes to the idea that the best way to learn - and thus, improve student educational outcomes - is through solving problems, yet recognizes that engineering students are generally provided insufficient opportunities to engage problems as they will be engaged in practice. Attempts to incorporate more open-ended, ill-structured experiences have increased but are challenging for faculty to implement because there are no systematic methods or approaches that support the educator in designing these learning experiences. Instead, faculty often start from the anchor of domain-specific concepts, an anchoring that is further reinforced by available textbook problems that are rarely open in nature. Open-ended problems are then created in ad-hoc ways, and in doing so, the problem-solving experience is often not realized as the instructor intended. Approach: The focus in this work is the development and preliminary implementation of a reflective approach to support instructors in examining the design intent of problem experiences. The reflective method combines concept mapping as developed by Joseph Novak with the work of David Jonassen and his characterization of problems and the forms of knowledge required to solve them. Results: We report on the development of a standard approach – a template -- for concept mapping of problems. As a demonstration, we applied the approach to a relatively simple, well-structured problem used in an introductory aerospace engineering course. Educator-created concept maps provided a visual medium for examining the connectivity of problem elements and forms of knowledge. Educator reflection after looking at and discussing the concept map revealed ways in which the problem engagement may differ from the perceived design intent. Implications: We consider the potential for the proposed method to support design and facilitation activities in problem-based learning (PBL) environments. We explore broader implications of the approach as it relates to 1) facilitating a priori faculty insights regarding student navigation of problem solving, 2) instructor reflection on problem design and facilitation, and 3) supporting problem design and facilitation. Additionally, we highlight important issues to be further investigated toward quantifying the value and limitations of the proposed approach. 

Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.

 

Measurements of Higgs boson production cross-sections are carried out in the diphoton decay channel using 139 fb⁻¹ofppcollision data at$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV collected by the ATLAS experiment at the LHC. The analysis is based on the definition of 101 distinct signal regions using machine-learning techniques. The inclusive Higgs boson signal strength in the diphoton channel is measured to be$$ {1.04}_{-0.09}^{+0.10} $$${1.04}_{-0.09}^{+0.10}$. Cross-sections for gluon-gluon fusion, vector-boson fusion, associated production with aWorZboson, and top associated production processes are reported. An upper limit of 10 times the Standard Model prediction is set for the associated production process of a Higgs boson with a single top quark, which has a unique sensitivity to the sign of the top quark Yukawa coupling. Higgs boson production is further characterized through measurements of Simplified Template Cross-Sections (STXS). In total, cross-sections of 28 STXS regions are measured. The measured STXS cross-sections are compatible with their Standard Model predictions, with ap-value of 93%. The measurements are also used to set constraints on Higgs boson coupling strengths, as well as on new interactions beyond the Standard Model in an effective field theory approach. No significant deviations from the Standard Model predictions are observed in these measurements, which provide significant sensitivity improvements compared to the previous ATLAS results.

 

A bstract A search for Higgs boson pair production in events with two b -jets and two τ -leptons is presented, using a proton–proton collision dataset with an integrated luminosity of 139 fb − 1 collected at $$ \sqrt{s} $$ s = 13 TeV by the ATLAS experiment at the LHC. Higgs boson pairs produced non-resonantly or in the decay of a narrow scalar resonance in the mass range from 251 to 1600 GeV are targeted. Events in which at least one τ -lepton decays hadronically are considered, and multivariate discriminants are used to reject the backgrounds. No significant excess of events above the expected background is observed in the non-resonant search. The largest excess in the resonant search is observed at a resonance mass of 1 TeV, with a local (global) significance of 3 . 1 σ (2 . 0 σ ). Observed (expected) 95% confidence-level upper limits are set on the non-resonant Higgs boson pair-production cross-section at 4.7 (3.9) times the Standard Model prediction, assuming Standard Model kinematics, and on the resonant Higgs boson pair-production cross-section at between 21 and 900 fb (12 and 840 fb), depending on the mass of the narrow scalar resonance. 

Abstract A study of the charge conjugation and parity ( $$\textit{CP}$$ CP ) properties of the interaction between the Higgs boson and $$\tau $$ τ -leptons is presented. The study is based on a measurement of $$\textit{CP}$$ CP -sensitive angular observables defined by the visible decay products of $$\tau $$ τ -leptons produced in Higgs boson decays. The analysis uses 139 fb $$^{-1}$$ - 1 of proton–proton collision data recorded at a centre-of-mass energy of $$\sqrt{s}= 13$$ s = 13  TeV with the ATLAS detector at the Large Hadron Collider. Contributions from $$\textit{CP}$$ CP -violating interactions between the Higgs boson and $$\tau $$ τ -leptons are described by a single mixing angle parameter $$\phi _{\tau }$$ ϕ τ in the generalised Yukawa interaction. Without constraining the $$H\rightarrow \tau \tau $$ H → τ τ signal strength to its expected value under the Standard Model hypothesis, the mixing angle $$\phi _{\tau }$$ ϕ τ is measured to be $$9^{\circ } \pm 16^{\circ }$$ 9 ∘ ± 16 ∘ , with an expected value of $$0^{\circ } \pm 28^{\circ }$$ 0 ∘ ± 28 ∘ at the 68% confidence level. The pure $$\textit{CP}$$ CP -odd hypothesis is disfavoured at a level of 3.4 standard deviations. The results are compatible with the predictions for the Higgs boson in the Standard Model.