Multi-year, spatially extensive, watershed-scale synoptic stream chemistry and water quality conditions for six permafrost-underlain Arctic watersheds

Repeated sampling of spatially distributed river chemistry can be used to assess the location, scale, and persistence of carbon and nutrient contributions to watershed exports. Here, we provide a comprehensive set of water chemistry measurements and ecohydrological metrics describing the biogeochemical conditions of permafrost-affected Arctic watersheds. These data were collected in watershed-wide synoptic campaigns in six stream networks across northern Alaska. Three watersheds are associated with the Arctic Long-Term Ecological Research site at Toolik Field Station (TFS), which were sampled seasonally each June and August from 2016 to 2018. Three watersheds were associated with the National Park Service (NPS) of Alaska and the U.S. Geological Survey (USGS) and were sampled annually from 2015 to 2019. Extensive water chemistry characterization included carbon species, dissolved nutrients, and major ions. The objective of the sampling designs and data acquisition was to characterize terrestrial–aquatic linkages and processing of material in stream networks. The data allow estimation of novel ecohydrological metrics that describe the dominant location, scale, and overall persistence of ecosystem processes in continuous permafrost. These metrics are (1) subcatchment leverage, (2) variance collapse, and (3) spatial persistence. Raw data are available at the National Park Service Integrated Resource Management Applications portal (O'Donnell et al., 2021, https://doi.org/10.5066/P9SBK2DZ) and within the Environmental Data Initiative (Abbott, 2021, https://doi.org/10.6073/pasta/258a44fb9055163dd4dd4371b9dce945).

Insertive condom-protected and condomless vaginal sex both have a profound impact on the penile immune correlates of HIV susceptibility

The penis is the primary site of HIV acquisition in heterosexual men. Elevated penile inflammatory cytokines increase sexual acquisition risk, and topically applied cytokines enhance foreskin HIV susceptibility in an explant model. However, the impact of penile-vaginal sex on these immune parameters is undefined. Heterosexual couples were recruited to the Sex, Couples and Science (SECS) Study, with the collection of penile swabs, semen, cervico-vaginal secretions, and blood after a period of abstinence, and repeated sampling up to 72 hours after either condomless (n = 30) or condom-protected (n = 8) penile-vaginal sex. Soluble immune parameters were quantified by multiplex immunoassay. Co-primary immune endpoints were penile levels of IL-8 and MIG, cytokines previously linked to penile HIV acquisition. One hour after sex there were dramatic increases in penile IL-8 and MIG levels, regardless of condom use, with a gradual return to baseline by 72 hours; similar patterns were observed for other chemoattractant chemokines. Penile cytokine changes were similar in circumcised and uncircumcised men, and repeated measures ANOVA and ANCOVA models demonstrated that the degree of change after condomless sex was explained by cytokine levels in their partners’ cervico-vaginal secretions. This may have important implications for the biology of penile HIV acquisition.

Competing cognitive pressures on human exploration in the absence of trade-off with exploitation

Exploring novel environments through sequential sampling is essential for efficient decision-making under uncertainty. In the laboratory, human exploration has been studied in situations where exploration is traded against reward maximisation. By design, these ‘explore-exploit’ dilemmas confound the behavioural characteristics of exploration with those of the trade-off itself. Here we designed a sequential sampling task where exploration can be studied and compared in the presence and absence of trade-off with exploitation. Detailed model-based analyses of choice behaviour revealed specific exploration patterns arising in situations where information seeking is not traded against reward seeking. Human choices are directed toward the most uncertain option available, but only after an initial sampling phase consisting of choice streaks from each novel option. These findings outline competing cognitive pressures on information seeking: the repeated sampling of the current option (for hypothesis testing), and the directed sampling of the most uncertain option available (for structure mapping).

Introducing Statistical Inference: Design of a Theoretically and Empirically Based Learning Trajectory

This paper comprises the results of a design study that aims at developing a theoretically and empirically based learning trajectory on statistical inference for 9th-grade students. Based on theories of informal statistical inference, an 8-step learning trajectory was designed. The trajectory consisted of two similar four step sequences: (1) experimenting with a physical black box, (2) visualizing distributions, (3) examining sampling distributions using simulation software, and (4) interpreting sampling distributions to make inferences in real -life contexts. Sequence I included only categorical data and Sequence II regarded numerical data. The learning trajectory was implemented in an intervention among 267 students. To examine the effects of the trajectory on students’ understanding of statistical inference, we analyzed their posttest results after the intervention. To investigate how the stepwise trajectory fostered the learning process, students’ worksheets during each learning step were analyzed. The posttest results showed that students who followed the learning trajectory scored significantly higher on statistical inference and on concepts related to each step than students of a comparison group (n = 217) who followed the regular curriculum. Worksheet analysis demonstrated that the 8-step trajectory was beneficial to students’ learning processes. We conclude that ideas of repeated sampling with a black box and statistical modeling seem fruitful for introducing statistical inference. Both ideas invite more advanced follow-up activities, such as hypothesis testing and comparing groups. This suggests that statistics curricula with a descriptive focus can be transformed to a more inferential focus, to anticipate on subsequent steps in students’ statistics education.

Breath and plasma metabolomics to assess inflammation in acute stroke

Inflammation is strongly implicated in both injury and repair processes occurring after stroke. In this exploratory study we assessed the feasibility of repeated sampling of exhaled volatile organic compounds and performed an untargeted metabolomic analysis of plasma collected at multiple time periods after stroke. Metabolic profiles were compared with the time course of the inflammatory markers C-reactive protein (CRP) and interleukin-6 (IL-6). Serial breath sampling was well-tolerated by all patients and the measurement appears feasible in this group. We found that exhaled decanal tracks CRP and IL-6 levels post-stroke and correlates with several metabolic pathways associated with a post-stroke inflammatory response. This suggests that measurement of breath and blood metabolites could facilitate development of novel therapeutic and diagnostic strategies. Results are discussed in relation to the utility of breath analysis in stroke care, such as in monitoring recovery and complications including stroke associated infection.

We are what we eat, plus some per mill: Using stable isotopes to estimate diet composition in Gyps vultures over space and time.

1. Dietary studies in birds of prey involve direct observation and examination of food remains at resting and nesting sites. Although these methods accurately identify diet in raptors, they are time-consuming, resource-intensive, and associated with biases from the feeding ecology of raptors like Gyps vultures. Our study set out to estimate diet composition in Gyps vultures informed by stable isotopes that provide a good representation of assimilated diet from local systems. 2. We hypothesized that differences in Gyps vulture diet composition is a function of sampling location, and that these vultures move between Serengeti National Park and Selous Game Reserve protected areas to forage. We also, theorised that grazing ungulates are the principal items in Gyps vulture diet. 3. Through combined linear and Bayesian modelling, diet-derived from 13C in Gyps vultures consisted of grazing herbivores across sites, with those in Serengeti National Park consuming higher proportions of grazing herbivores (> 87%). 13C differences in vulture feather subsets did not indicate shifts in vulture diet and combined with blood 13C, vultures fed largely on grazers for ~159 days before they were sampled. Similarly, 15N values indicated Gyps vultures fed largely on herbivores. 34S ratios separated where vultures fed when the two sites were compared. 34S variation in vultures across sites resulted from baseline differences in plant 34S values, though it is not possible to match 34S to specific locations. 4. Our findings highlight the relevance of repeated sampling that considers tissues with varying isotopic turnover and emerging Bayesian techniques for dietary studies using stable isotopes. Findings also suggested limited vulture movement between the two local systems. However, more sampling coupled with telemetry is required to fully comprehend this observation and its implications to Gyps vulture ecology and conservation.

Improved Detectability of Plasmodium falciparum Clones with Repeated Sampling in Incident and Chronic Infections in Burkina Faso

We evaluated the detectability of Plasmodium falciparum clones when assessed on 3 consecutive days in incident and chronic infections in naturally exposed children living in an area of intense malaria transmission in Burkina Faso. The median number of clones by merozoite surface protein 2 (MSP2) genotyping was 3 (interquartile range [IQR] 2–5) in incident infections compared with 6 (IQR 4–8) in chronic infections (P < 0.0001). When all clones detected on days 1-3 were considered as true complexity of infection, sampling on day 1 detected only 69.4% (109/157) or 68.3% (228/334) of all clones in incident and chronic infections, respectively. Our findings demonstrate that a large proportion of clones are missed by single time-point sampling. In addition, because of the high complexity of infection early in incident infections, our data suggest many infections may be caused by genetically complex inocula.

We are what we eat, plus some per mill: Using stable isotopes to estimate diet composition in Gyps vultures over space and time.

1. Dietary studies in birds of prey involve direct observation and examination of food remains at resting and nesting sites. Although these methods accurately identify diet in raptors, they are time-consuming, resource-intensive, and associated with biases from the feeding ecology of raptors like Gyps vultures. Our study set out to estimate diet composition in Gyps vultures informed by stable isotopes that provide a good representation of assimilated diet from local systems. 2. We hypothesized that differences in Gyps vulture diet composition is a function of sampling location, and that these vultures move between Serengeti National Park and Selous Game Reserve protected areas to forage. We also, theorised that grazing ungulates are the principal items in Gyps vulture diet. 3. Through combined linear and Bayesian modelling, diet-derived from 13C in Gyps vultures consisted of grazing herbivores across sites, with those in Serengeti National Park consuming higher proportions of grazing herbivores (> 87%). 13C differences in vulture feather subsets did not indicate shifts in vulture diet and combined with blood 13C, vultures fed largely on grazers for ~159 days before they were sampled. Similarly, 15N values indicated Gyps vultures fed largely on herbivores. 34S ratios separated where vultures fed when the two sites were compared. 34S variation in vultures across sites resulted from baseline differences in plant 34S values, though it is not possible to match 34S to specific locations. 4. Our findings highlight the relevance of repeated sampling that considers tissues with varying isotopic turnover and emerging Bayesian techniques for dietary studies using stable isotopes. Findings also suggested limited vulture movement between the two local systems. However, more sampling coupled with telemetry is required to fully comprehend this observation and its implications to Gyps vulture ecology and conservation.

Temporal Associations of the SARS-CoV-2 NP Antigen and Anti-Spike Total Ig Levels with Laboratory Parameters in a Greek Cohort of Hospitalized COVID-19 Patients

Background. The direct effect of SARS-CoV-2 on the lungs results in increased hospitalization rates of patients with pneumonia. Severe COVID-19 patients often develop ARDS which is associated with poor prognosis. Assessing risk factors for COVID-19 severity is indispensable for implementing and evaluating therapeutic interventions. We investigated the temporal associations between the SARS-CoV-2 antigen (Ag), total Immunoglobulin (Ig) levels, and several laboratory parameters in hospitalized patients with varying degrees of COVID-19 severity. Methods. The SARS-CoV-2 nucleocapsid protein (NP) and total Ig Spike (S) protein-specific antibodies were determined for each patient with lateral flow assays through repeated sampling every two days. Hematological and biochemical parameters were evaluated at the same time points. Results. 40 Greek COVID-19 patients (31 males, 9 females) with a median age of 59.50 ± 16.21 years were enrolled in the study. The median time from symptom onset to hospitalization was 8.0 ± 4.19 days. A significant negative correlation was observed between the SARS-CoV-2 Ag and total Ig levels. The temporal correlation patterns of the SARS-CoV-2 NP Ag and anti-S total Ig levels with laboratory markers varied among patients with differing degrees of COVID-19 severity. Severe-critical cases had lower SARS-CoV-2 Ag and increased total Ig levels as compared to mild-moderate cases. Conclusions. Distinct temporal profiles of the SARS-CoV-2 NP Ag and anti-S total Ig levels may distinguish different groups of COVID-19 severity.