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Rapid warming in the Arctic threatens to destabilize mercury (Hg) deposits contained within soils in permafrost regions. Yet current estimates of the amount of Hg in permafrost vary by ∼4 times. Moreover, how Hg will be released to the environment as permafrost thaws remains poorly known, despite threats to water quality, human health, and the environment. Here we present new measurements of total mercury (THg) contents in discontinuous permafrost in the Yukon River Basin in Alaska. We collected riverbank and floodplain sediments from exposed banks and bars near the villages of Huslia and Beaver. Median THg contents were 49 +13 / −21 ng THg g sediment −1 and 39 +16 / −18 ng THg g sediment −1 for Huslia and Beaver, respectively (uncertainties as 15th and 85th percentiles). Corresponding THg:organic carbon ratios were 5.4 +2.0 / −2.4 Gg THg Pg C −1 and 4.2 +2.4 / −2.9 Gg THg Pg C −1 . To constrain floodplain THg stocks, we combined measured THg contents with floodplain stratigraphy. Trends of THg increasing with smaller sediment size and calculated stocks in the upper 1 m and 3 m are similar to those suggested for this region by prior pan-Arctic studies. We combined THg stocks and river migration rates derived from remote sensing to estimate particulate THg erosional and depositional fluxes as river channels migrate across the floodplain. Results show similar fluxes within uncertainty into the river from erosion at both sites (95 +12 / −47 kg THg yr −1 and 26 +154 / −13 kg THg yr −1 at Huslia and Beaver, respectively), but different fluxes out of the river via deposition in aggrading bars (60 +40 / −29 kg THg yr −1 and 10 +5.3 / −1.7 kg THg yr −1 ). Thus, a significant amount of THg is liberated from permafrost during bank erosion, while a variable but generally lesser portion is subsequently redeposited by migrating rivers.

Indigenous Arctic and Subarctic communities currently are facing a myriad of social and environmental changes. In response to these changes, studies concerning indigenous knowledge (IK) and climate change vulnerability, resiliency, and adaptation have increased dramatically in recent years. Risks to lives and livelihoods are often the focus of adaptation research; however, the cultural dimensions of climate change are equally important because cultural dimensions inform perceptions of risk. Furthermore, many Arctic and Subarctic IK climate change studies document observations of change and knowledge of the elders and older generations in a community, but few include the perspectives of the younger population. These observations by elders and older generations form a historical baseline record of weather and climate observations in these regions. However, many indigenous Arctic and Subarctic communities are composed of primarily younger residents. We focused on the differences in the cultural dimensions of climate change found between young adults and elders. We outlined the findings from interviews conducted in four indigenous communities in Subarctic Alaska. The findings revealed that (1) intergenerational observations of change were common among interview participants in all four communities, (2) older generations observed more overall change than younger generations interviewed by us, and (3) how change was perceived varied between generations. We defined “observations” as the specific examples of environmental and weather change that were described, whereas “perceptions” referred to the manner in which these observations of change were understood and contextualized by the interview participants. Understanding the differences in generational observations and perceptions of change are key issues in the development of climate change adaptation strategies.

Using a result of Vdovina, we may associate to each complete connected bipartite graph $\\kappa $ a two-dimensional square complex, which we call a tile complex, whose link at each vertex is $\\kappa $ . We regard the tile complex in two different ways, each having a different structure as a $2$ -rank graph. To each $2$ -rank graph is associated a universal $C^{\\star }$ -algebra, for which we compute the K-theory, thus providing a new infinite collection of $2$ -rank graph algebras with explicit K-groups. We determine the homology of the tile complexes and give generalisations of the procedures to complexes and systems consisting of polygons with a higher number of sides.

The scarcity of malignant Hodgkin and Reed–Sternberg cells hampers tissue-based comprehensive genomic profiling of classic Hodgkin lymphoma (cHL). By contrast, liquid biopsies show promise for molecular profiling of cHL due to relatively high circulating tumour DNA (ctDNA) levels 1 – 4 . Here we show that the plasma representation of mutations exceeds the bulk tumour representation in most cases, making cHL particularly amenable to noninvasive profiling. Leveraging single-cell transcriptional profiles of cHL tumours, we demonstrate Hodgkin and Reed–Sternberg ctDNA shedding to be shaped by DNASE1L3, whose increased tumour microenvironment-derived expression drives high ctDNA concentrations. Using this insight, we comprehensively profile 366 patients, revealing two distinct cHL genomic subtypes with characteristic clinical and prognostic correlates, as well as distinct transcriptional and immunological profiles. Furthermore, we identify a novel class of truncating IL4R mutations that are dependent on IL-13 signalling and therapeutically targetable with IL-4Rα-blocking antibodies. Finally, using PhasED-seq 5 , we demonstrate the clinical value of pretreatment and on-treatment ctDNA levels for longitudinally refining cHL risk prediction and for detection of radiographically occult minimal residual disease. Collectively, these results support the utility of noninvasive strategies for genotyping and dynamic monitoring of cHL, as well as capturing molecularly distinct subtypes with diagnostic, prognostic and therapeutic potential. The potential use of circulating tumour DNA in classic Hodgkin lymphoma detection, classification and monitoring is defined.

Rivers integrate processes occurring throughout their watersheds and are therefore sentinels of change across broad spatial scales. River chemistry also regulates ecosystem function across Earth’s land–ocean continuum, exerting control from the micro- (for example, local food web) to the macro- (for example, global carbon cycle) scale. In the rapidly warming Arctic, a wide range of processes—from permafrost thaw to biological uptake and transformation—might reasonably alter river water chemistry. Here we use data from major rivers that collectively drain two-thirds of the Arctic Ocean watershed to assess widespread change in biogeochemical function within the pan-Arctic basin from 2003 to 2019. While the oceanward flux of alkalinity and associated ions increased markedly over this time frame, nitrate and other inorganic nutrient fluxes declined. Fluxes of dissolved organic carbon showed no overall trend. This divergence in response indicates the perturbation of multiple processes on land, with implications for biogeochemical cycling in the coastal ocean. We anticipate that these findings will facilitate refinement of conceptual and numerical models of current and future functioning of Arctic coastal ecosystems and spur research on scale-dependent change across the river-integrated Arctic domain.Divergent trends in biogeochemical constituents of the six largest rivers in the Arctic from 2003 to 2019 support multi-faceted changes on the Arctic landscape under global environmental change.

Arctic rivers provide an integrated signature of the changing landscape and transmit signals of change to the ocean. Here, we use a decade of particulate organic matter (POM) compositional data to deconvolute multiple allochthonous and autochthonous pan-Arctic and watershed-specific sources. Constraints from carbon-to-nitrogen ratios (C:N), δ13C, and Δ14C signatures reveal a large, hitherto overlooked contribution from aquatic biomass. Separation in Δ14C age is enhanced by splitting soil sources into shallow and deep pools (mean ± SD: −228 ± 211 vs. −492 ± 173‰) rather than traditional active layer and permafrost pools (−300 ± 236 vs. −441 ± 215‰) that do not represent permafrost-free Arctic regions. We estimate that 39 to 60% (5 to 95% credible interval) of the annual pan-Arctic POM flux (averaging 4,391 Gg/y particulate organic carbon from 2012 to 2019) comes from aquatic biomass. The remainder is sourced from yedoma, deep soils, shallow soils, petrogenic inputs, and fresh terrestrial production. Climate change-induced warming and increasing CO₂ concentrations may enhance both soil destabilization and Arctic river aquatic biomass production, increasing fluxes of POM to the ocean. Younger, autochthonous, and older soil-derived POM likely have different destinies (preferential microbial uptake and processing vs. significant sediment burial, respectively). A small (~7%) increase in aquatic biomass POM flux with warming would be equivalent to a ~30% increase in deep soil POM flux. There is a clear need to better quantify how the balance of endmember fluxes may shift with different ramifications for different endmembers and how this will impact the Arctic system.

The efficiency of water resource management in any country is measured by the extent of its water balance. Recently, Recently, Iraq has been facing major challenges in achieving water balance as a result of the decline in its water inflows on the one hand and the increase in water consumption due to climate change on the other hand. In addition to the water policies followed by upstream countries. In addition, rapid population growth and the expansion of irrigated agriculture have contributed to putting the water balance under pressure. Consequently, exacerbated the water deficit, in addition to water quality deterioration. Subsequently, increasing risks facing water security in Iraq. The results of the current study indicate that Iraq has shifted from a country of water abundance during the last century to a country of water poverty at the beginning of the current century and has entered a phase of water scarcity after 2020. The study results also indicated that in recent years the water deficit has risen to 100%. Additionally, the Iraqi water quality has significantly degraded owing to pollution. Therefore, the results of the current study concluded that it is necessary to activate effective management to increase external water inflows on the one hand and rationalize the use of available water on the other hand to achieve the sustainability of this resource and preserve its quality.

This experiment investigated how prior beliefs affect young and older adults' ability to detect differences in objective contingency. Participants received new evidence that the objective contingency between two events was positive, negative, or zero when they believed that there was a positive or negative relationship between events, when they believed that the events were unrelated, and when they had no knowledge of the relationship between the events. They were then asked to estimate the objective contingency and recall the contingency evidence. Beliefs that events were or could be related improved young adults' contingency discrimination. Moreover, these beliefs did not produce biases in young adults' memory for the contingency evidence, but rather affected how they weighted this evidence at judgment. In contrast, these same beliefs did not improve older adults' contingency discrimination, but did produce biases in their memory for the evidence that were similar to those seen in their judgment. These findings are discussed in terms of age-related changes in working memory executive processes that impair older adults' ability to fully evaluate both belief-confirming and disconfirming contingency evidence and update their beliefs with this information.

The challenge of sustaining user engagement in eHealth interventions is a pressing issue with significant implications for the effectiveness of these digital health tools. This study investigates user engagement in a cognitive-behavioral therapy-based eHealth intervention for procrastination, using a dataset from a randomized controlled trial of 233 university students. Various machine learning models, including Decision Tree, Gradient Boosting, Logistic Regression, Random Forest, and Support Vector Machines, were employed to predict patterns of user engagement. The study adopted a two-phase analytical approach. In the first phase, all features of the dataset were included, revealing ‘total_minutes’—the total time participants spent on the intervention and the eHealth platform—as the most significant predictor of engagement. This finding emphasizes the intuitive notion that early time spent on the platform and the intervention is a strong indicator of later user engagement. However, to gain a deeper understanding of engagement beyond this predominant metric, the second phase of the analysis excluded ‘total_minutes’. This approach allowed for the exploration of the roles and interdependencies of other engagement indicators, such as ‘number_intervention_answersheets’—the number of completed lessons, ‘logins_first_4_weeks’—login frequency, and ‘number_diary_answersheets’—the number of completed diaries. The results from this phase highlighted the multifaceted nature of engagement, showing that while ‘total_minutes’ is strongly correlated with engagement, indicating that more engaged participants tend to spend more time on the intervention, the comprehensive engagement profile also depends on additional aspects like lesson completions and frequency of platform interactions.

Public attitudes vary across mental health (MH) problems. However, research on young people and certain MH conditions is limited. This online-experiment examined stigma and potential help-seeking among 554 adolescents and emerging adults aged 14–29 years towards generalized anxiety disorder, depression (DEP), bulimia nervosa (BN), non-suicidal self-injury (NSSI), and problematic alcohol use (ALC). Participants were randomized to a video vignette depicting one of the five MH problems. Attitudes were measured with the Universal Stigma Scale (subscales: “blame/ personal responsibility” and “impairment/ distrust”) and the General Help Seeking Questionnaire assessing the likelihoods of seeking professional, informal, and no help for the respective MH problem. Data were analysed using Kruskal-Wallis and Bonferroni-corrected Dunn’s tests. Compared to all of the other conditions, ALC was the most stigmatized. Furthermore, ALC was more likely to prompt any help-seeking as compared to DEP, BN, and NSSI, and professional help-seeking in comparison to DEP. BN elicited more blame than DEP, whereas the reverse pattern emerged for distrust. However, this sample generally held positive MH attitudes. The results highlight the importance of addressing disorder-specific stigma and may inform the development of targeted anti-stigma and help-seeking campaigns. Trial registration : This study has been registered at the German Clinical Trials Register (www.drks.de) on September 23rd, 2020 https//drks.de/search/de/trial/DRKS00023110 #DRKS00023110.