BACKGROUND: Specific land cover types and activities have been correlated with Trypanosoma brucei rhodesiense distributions, indicating the importance of landscape for epidemiological risk. However, methods proposed to identify specific areas with elevated epidemiological risk (i.e. where transmission is more likely to occur) tend to be costly and time consuming. This paper proposes an exploratory spatial analysis using geo-referenced human African trypanosomiasis (HAT) cases and matched controls from Serere hospital, Uganda (December 1998 to November 2002) to identify areas with an elevated epidemiological risk of HAT. METHODS: Buffers 3 km from each case and control were used to represent areas in which village inhabitants would carry out their daily activities. It was hypothesised that the selection of areas where several case village buffers overlapped would enable the identification of locations with increased risk of HAT transmission, as these areas were more likely to be frequented by HAT cases in several surrounding villages. The landscape within these overlap areas should more closely relate to the environment in which transmission occurs as opposed to using the full buffer areas. The analysis was carried out for each of four annual periods, for both cases and controls, using a series of threshold values (number of overlapping buffers), including a threshold of one, which represented the benchmark (e.g. use of the full buffer area as opposed to the overlap areas). RESULTS: A greater proportion of the overlap areas for cases consisted of seasonally flooding grassland and lake fringe swamp, than the control overlap areas, correlating well with the preferred habitat of the predominant tsetse species within the study area (Glossina fuscipes fuscipes). The use of overlap areas also resulted in a greater difference between case and control landscapes, when compared with the benchmark (using the full buffer area). CONCLUSIONS: These results indicate that the overlap analysis has enabled the selection of areas more likely to represent epidemiological risk zones than similar analyses using full buffer areas. The identification of potential epidemiological risk zones using this method requires fewer data than other proposed methods and further development may provide vital information for the targeting of control measures.
Sequencing-based studies of the human faecal microbiota are increasingly common. Appropriate storage of sample material is essential to avoid the introduction of post-collection bias in microbial community composition. Rapid freezing to -80 °C is commonly considered to be best-practice. However, this is not feasible in many studies, particularly those involving sample collection in participants' homes. We determined the extent to which a range of stabilisation and storage strategies maintained the composition of faecal microbial community structure relative to freezing to -80 °C. Refrigeration at 4 °C, storage at ambient temperature, and the use of several common preservative buffers (RNAlater, OMNIgene.GUT, Tris-EDTA) were assessed relative to freezing. Following 72 hours of storage, faecal microbial composition was assessed by 16 S rRNA amplicon sequencing. Refrigeration was associated with no significant alteration in faecal microbiota diversity or composition. However, samples stored using other conditions showed substantial divergence compared to -80 °C control samples. Aside from refrigeration, the use of OMNIgene.GUT resulted in the least alteration, while the greatest change was seen in samples stored in Tris-EDTA buffer. The commercially available OMNIgene.GUT kit may provide an important alternative where refrigeration and cold chain transportation is not available.
- Proceedings of the National Academy of Sciences of the United States of America
- Published almost 9 years ago
Across diverse ecosystems, greater climatic variability tends to increase wildfire size, particularly in Australia, where alternating wet-dry cycles increase vegetation growth, only to leave a dry overgrown landscape highly susceptible to fire spread. Aboriginal Australian hunting fires have been hypothesized to buffer such variability, mitigating mortality on small-mammal populations, which have suffered declines and extinctions in the arid zone coincident with Aboriginal depopulation. We test the hypothesis that the relationship between climate and fire size is buffered through the maintenance of an anthropogenic, fine-grained fire regime by comparing the effect of climatic variability on landscapes dominated by Martu Aboriginal hunting fires with those dominated by lightning fires. We show that Aboriginal fires are smaller, more tightly clustered, and remain small even when climate variation causes huge fires in the lightning region. As these effects likely benefit threatened small-mammal species, Aboriginal hunters should be considered trophic facilitators, and policies aimed at reducing the risk of large fires should promote land-management strategies consistent with Aboriginal burning regimes.
Stress is a major cause of poor health and mortality in humans and other social mammals. Close social bonds buffer stress, however much of the underlying physiological mechanism remains unknown. Here, we test two key hypotheses: bond partner effects occur only during stress (social buffering) or generally throughout daily life (main effects). We assess urinary glucocorticoids (uGC) in wild chimpanzees, with or without their bond partners, after a natural stressor, resting or everyday affiliation. Chimpanzees in the presence of, or interacting with, bond partners rather than others have lowered uGC levels across all three contexts. These results support the main effects hypothesis and indicate that hypothalamic-pituitary-adrenocortical (HPA) axis regulation is mediated by daily engagement with bond partners both within and out of stressful contexts. Regular social support with bond partners could lead to better health through daily ‘micro-management’ of the HPA axis, a finding with potential medical implications for humans.
The present study tested whether pet dogs have stress-buffering effects for children during a validated laboratory-based protocol, the Trier Social Stress Test for Children (TSST-C). Participants were 101 children aged 7-12 years with their primary caregivers and pet dogs. Children were randomly assigned in the TSST-C to a pet present condition or one of two comparison conditions: parent present or no support figure present. Baseline, response, and recovery indices of perceived stress and cortisol levels were computed based on children’s self-reported feelings of stress and salivary cortisol. Results indicated that in the alone (no social support) condition, children showed the expected rise for both perceived stress and cortisol response to stress. Pet dog presence significantly buffered the perceived stress response in comparison to children in the alone and parent present conditions. No main condition effect was observed for cortisol; however, for children experiencing the stressor with their pet present, lower cortisol response to stress was associated with more child-initiated petting and less dog proximity-seeking behavior. The results support the notion that pet dogs can provide socio-emotional benefits for children via stress buffering.
Conflict can have damaging effects on relationship health. But is all conflict detrimental? Across 7 studies, we tested the overarching hypothesis that conflict in close relationships is only detrimental when people do not feel their thoughts, feelings, and point of view are understood by their relationship partners. Supporting this, conflict was negatively associated with relationship satisfaction among participants who perceived their romantic partner as less understanding, but not among those who felt more understood by their partners. This was true cross-sectionally (Study 1), experimentally (Studies 2, 3, 6a, and 6b), in daily life (Study 4), and for both members of couples pre- to postconflict conversation in the laboratory (Study 5). The buffering effects of feeling understood could not be explained by people who felt more understood being more understanding themselves, having more general positive perceptions of their partners, fighting about less important or different types of issues, engaging in more pleasant conflict conversations, or being more satisfied with their relationships before the conflict. Perceived understanding was positively associated with conflict resolution, but this did not explain the benefits of feeling understood. Evidence from Studies 6a and 6b suggests that feeling understood during conflict may buffer against reduced relationship satisfaction in part because it strengthens the relationship and signals that one’s partner is invested. Overall, these studies suggest that perceived understanding may be a critical buffer against the potentially detrimental effects of relationship conflict. (PsycINFO Database Record
The association between shyness and children’s likeability by peers was examined, with pragmatic difficulty and receptive and expressive vocabularies as moderators. Participants were 164 preschoolers (72 boys, 92 girls) between 52 and 79 months old in Singapore. A cross-informant methodology was used, with peers and teachers contributing to separate peer likeability ratings. The findings highlighted a conceptual distinction between peer- and teacher-rated likeability by peers. For the latter only, a 3-way interaction involving shyness, vocabulary, and pragmatic difficulty was found, indicating that for shy children with low vocabulary scores, those who experienced less pragmatic difficulty tended to be seen by teachers as more well-liked by peers than those with more pragmatic difficulty. This suggests that pragmatic skills may serve a protective function especially for shy children with poor vocabulary skills. Statement of contribution What is already known on this subject? Child shyness is related to poorer peer acceptance and social competence Expressive vocabulary and pragmatic competence each has a buffering effect for shy children What the present study adds? Shyness is related to poorer peer likeability as assessed by teachers Shyness is unrelated to peer likeability as assessed by same- or different-sex peers Pragmatic skills buffer the effects of teacher-rated shyness only for children with poor receptive and expressive vocabularies The buffering effect of language ability is shown in a multilingual educational context.
Single Molecule Localization super-resolution Microscopy (SMLM) has become a powerful tool to study cellular architecture at the nanometer scale. In SMLM, single fluorophore labels are made to repeatedly switch on and off (“blink”), and their exact locations are determined by mathematically finding the centers of individual blinks. The image quality obtainable by SMLM critically depends on efficacy of blinking (brightness, fraction of molecules in the on-state) and on preparation longevity and labeling density. Recent work has identified several combinations of bright dyes and imaging buffers that work well together. Unfortunately, different dyes blink optimally in different imaging buffers, and acquisition of good quality 2- and 3-color images has therefore remained challenging. In this study we describe a new imaging buffer, OxEA, that supports 3-color imaging of the popular Alexa dyes. We also describe incremental improvements in preparation technique that significantly decrease lateral- and axial drift, as well as increase preparation longevity. We show that these improvements allow us to collect very large series of images from the same cell, enabling image stitching, extended 3D imaging as well as multi-color recording.
Many individuals feel socially isolated and distressed in ethnically diverse settings. Purpose in life may buffer this form of distress by fostering one’s sense of having a meaningful direction, which may also be of significance to others. In two experience-sampling studies with ethnically diverse participants, we examined associations between the ethnic composition of urban trains and passenger distress, and tested purpose as a moderator of these relationships. Study 1 showed that participants of all ethnic backgrounds reported greater negative mood when the percentage of ethnic out-group members aboard their train increased. However, individual differences in purpose significantly attenuated this effect. Study 2 replicated and extended these findings experimentally by showing that relative to a control condition, briefly writing about purpose prior to boarding trains also diminished the impact of ethnic composition on negative mood. The discussion addresses strategies for promoting positive adjustment in our increasingly diverse society.
Providing help or support to others buffers the associations between stress and physical health. We examined the function of the neurohormone oxytocin as a biological mechanism for this stress-buffering phenomenon. Participants in a longitudinal study completed a measure of charitable behavior, and over the next two years provided assessments of stressful life events and physician-diagnosed physical ailments. Results indicated that charitable behavior buffered the associations between stressful events and new-onset ailments among individuals with the AA/AG genotypes of oxytocin receptor gene (OXTR) variant rs53576, but not among those with the GG genotype. These results suggest that oxytocin function may significantly affect health and may help explain the associations between prosocial behavior and health. More broadly, these findings are consistent with a role for the caregiving behavioral system in health and well-being.