Context. High-mass stars and star clusters form from the fragmentation of massive dense clumps driven by gravity, turbulence, and magnetic fields. The extent to which each of these agents impacts the fragmentation depending on the clump mass, density, and evolutionary stage is still largely unknown. Aims. The ALMA evolutionary study of high-mass protocluster formation in the GALaxy (ALMAGAL) project, with similar to 1000 clumps observed at similar to 1000 au resolution, allows a statistically significant characterization of the fragmentation process over a large range of clump physical parameters and evolutionary stages. Our goal is to characterize where and how the dense cores revealed by ALMA are distributed in massive potentially cluster-forming clumps to trace how fragmentation is initially set and how it proceeds before gas dispersal due to stellar feedback. Methods. We characterized the spatial distribution of dense cores in the 514 ALMAGAL clumps that host at least four cores, using a set of quantitative descriptors that we evaluated against the clump bolometric luminosity-to-mass ratio, which we adopted as an indicator of the evolution of the system. We measured the separations between cores with the minimum spanning tree (MST) method, which we compared with the predictions of gravitational fragmentation from Jeans theory. We investigated whether cores have specific arrangements using the Q parameter or variations due to their masses with the mass segregation ratio, Lambda(MSR). Results. ALMAGAL cores are distributed throughout the entire area of the clump, usually arranged in elliptical groups with an axis ratio e similar to 2.2, although high values with e >= 5 are also observed. We found a single characteristic core separation per clump in similar to 76% of cases, suggesting that multiple fragmentation lengths may be frequently present. Typical core separations are compatible with the clump-averaged thermal Jeans length,lambda(th)(J). However, we found an additional population of cores, typical of low-fragmented and young clumps, which are on average more widely separated with l approximate to 3 & times; lambda(th)(J). By stacking the distributions of the core separations in clumps of similar evolutionary stage, we also found that the separation decreases on average from l similar to 22 000 au in younger systems to l similar to 7000 au in more evolved ones. The ALMAGAL cores are typically distributed in fractal-type subclusters, while centrally concentrated patterns appear only at later stages, but we do not observe a progressive transition between these configurations with evolution. Finally, we also found 110 ALMAGAL systems with a signature of mass segregation, with an occurrence that increases with evolution.
Benthic iron (Fe) fluxes from coastal sediments support phytoplankton blooms downstream of subpolar islands. We combine solid-phase and pore-water geochemical data, including its iron isotopic signature (delta 56Feaq), to identify the main drivers of benthic Fe fluxes from sub-Antarctic fjord and shelf sediments of South Georgia, and to evaluate the potential of delta 56Feaq as a proxy for benthic Fe fluxes. A high accumulation rate of total organic carbon compresses the redox zonation in the near-surface sediment column and controls benthic Fe efflux. Sites with low diffusive Fe fluxes show a broad delta 56Feaq range close to the sediment-water interface (-3.94 +/- 0.14 parts per thousand to -0.98 +/- 0.11 parts per thousand), while sites with high benthic Fe fluxes exhibit a slightly narrower range (-3.14 +/- 0.02 parts per thousand and -1.64 +/- 0.06 parts per thousand). The broader isotopic range in low benthic Fe flux settings reflects the diverse processes that entail low net benthic Fe fluxes into the bottom water. Low- and high rates of microbial iron reduction may result in similar Fe isotope composition of diffusive benthic Fe efflux, if the latter is combined with high rates of Fe removal from pore-water by iron sulfide formation. A narrow range of delta 56Feaq within the oxic redox zone appears to be a recurrent feature at sites of high benthic Fe fluxes, but we recommend accounting for all early diagenetic Fe cycling processes and the depositional regime when interpreting low delta 56Feaq values in the near bottom water.
Graphs play a central role in chemistry education, serving as powerful tools for visualizing abstract concepts. However, their high information density and abstract nature can overwhelm students, often resulting in learning difficulties. Developing graph competence is therefore essential. While research on graph use and comprehension is well established in science education, investigations specific to chemistry remain limited. This study addresses this gap by systematically analyzing the use of graphs in eight German middle and secondary school chemistry textbooks, identifying and examining 3550 visual representations to provide a more precise understanding of graph use in chemistry and its implications for learning and teaching. The analysis quantified and compared the prevalence and distribution of graphs and realistic pictures across content areas and educational levels. Focusing on line graphs, we also analyzed how graph-related textbook tasks engage students in cognitive processes at varying levels of complexity. Our findings reveal not only the variety of graph types in chemistry textbooks but also distinct differences in the cognitive demands placed on students across educational levels and school types. Furthermore, they highlight domain-specific characteristics of graphs in chemistry and suggest challenges that students are likely to encounter when engaging with them. By identifying these patterns, the study extends previous research on graph use through its focused chemistry education context and provides actionable insights for improving textbook design and instructional strategies. Finally, this work lays the groundwork for future research into students' actual graph competence and graph-related difficulties.
Faithful DNA replication is essential for genome stability, yet replication forks face constant stress. The Bloom syndrome helicase (BLM) safeguards fork integrity, but excessive BLM activity can itself induce replication stress. We identify SLX4IP as a genome-wide regulator that restrains BLM to maintain replication fork stability. SLX4IP localizes broadly across chromatin with recruitment enhanced under replication stress. Loss of SLX4IP slows replication forks, remodels the replisome, and generates post-replicative single-stranded DNA gaps that are accompanied by elevated nuclear ADP ribose, reflecting compromised replication integrity. These defects are driven by dysregulated BLM activity, establishing SLX4IP as a negative regulator of BLM-dependent replication stress. At ALT telomeres, SLX4IP deficiency triggers ATR signaling, telomere fragility, and accumulation of ALT-associated PML bodies. Here, SLX4IP functions in parallel with FANCM to restrain BLM at ALT telomeres, with co-depletion of SLX4IP and FANCM causing synthetic lethality in ALT-positive cells, a phenotype fully rescued by BLM loss. Together, our results define SLX4IP as a critical genome-wide regulator of replication fork integrity and reveal SLX4IP as a potential vulnerability in ALT-positive cancers.
Post-COVID syndrome (PCS) refers to persistent or new-onset symptoms 3 months after SARS-CoV-2 infection lasting for at least 2 months. The characterization of PCS varies across studies, with a substantial heterogeneity regarding different study samples, survey instruments, and follow-up periods. This is particularly the case in hospitalized patients vs. outpatients, as well as regarding different variants of concern (VOCs) and their impact on the frequency and severity of specific symptoms. The study population of Beyond COVID was recruited in six German cities by inviting (1) individuals registered as SARS-CoV-2 PCR positive at the local Public Health Authorities and (2) previously hospitalized patients with infection date after 1st March 2021. Participants were allocated to the predominant VOC of their first infection. Questionnaires to assess pre-existing conditions, symptoms during infection, and persisting symptomswere performed. Follow-up at sixth-month intervals is planned for 3 years. The study is ongoing. This publication describes the parameters at the baseline visit (BV). We included 1257 participants (13
