Do daily mood fluctuations activate ruminative thoughts as a mental habit?:Results from an ecological momentary assessment study

It has been suggested that mental habits may underpin a heightened disposition to engage in rumination in response to negative mood. The aim of the current study was to assess the role of habit in the dynamic interplay between affect and ruminative thinking in the flow of daily life experiences. Using mobile ecological momentary assessment, 97 participants recorded affect and rumination ten times daily over six days, after completing measures of trait ruminative brooding and habitual characteristics of negative thinking (e.g. automaticity, lack of conscious awareness, intent and control). Momentary fluctuations in negative (increased) and positive (decreased) affect was prospectively associated with greater rumination-levels at the next sampling occasion. The degree to which affect triggered a subsequent ruminative response was moderated by habitual characteristics of negative thinking in a theoretically consistent way. Stronger temporal pairing of negative affect and rumination was also associated with greater emotional inertia but less carry-over of rumination from one moment to the next. Depression vulnerability may be in the form of rumination being habitually triggered in response to momentary fluctuations in affect, with deleterious effect on mood. The findings may have clinical implications, as targeting the habitual nature of rumination might help reduce depression vulnerability

Sjálfvirkni þunglyndisþanka í daglegu lífi: Rannsóknir á vanabundnu eðli þunglyndisþanka í úrtökum háskólanema og fólks með endurtekið þunglyndi. Innsýn úr snjallsímamælingum

Background: Major depression is the most common psychiatric disorder, associated with the highest disease burden worldwide when it comes to years lost to disability. Efforts to identify indicators of depression risk have strongly implicated depressive rumination, a negative thinking style characterized by repetitive and passive thoughts about the causes, meanings, and consequences of one's feelings and distress. An increasingly popular theoretical perspective posits that over time depressive rumination becomes a mental habit that is initiated automatically without conscious awareness or intent in response to downward shifts in mood, making it persistent and difficult to control. However, the rumination as-a-habit account has rarely been directly tested and it is still unknown whether depression vulnerability is characterized by elevated levels of mood-reactive habitual rumination at the level of short-term dynamics. Aims: The aim of the current research project was to address gaps in the current knowledge on depression vulnerability by utilizing a combination of experimental and novel mobile in-the-moment assessment strategies to better understand the dynamic interplay between mood and ruminative thinking and its habitual characteristics. Three studies were designed to test specific hypotheses involving: a) effects that fluctuations in mood have on subsequent ruminative thinking, b) the degree to which habitual characteristics of negative thinking predict such mood-reactive rumination, and c) whether mood-reactive rumination varies according to the depression-risk spectrum in line with theoretical accounts of depression vulnerability. Methods: In study 1, a total of 115 university students completed self-report measures and participated in an experimental rumination-induction task and outcome-devaluation task measuring habit vs. goal-directed behaviour control. In study 2, a total of 97 participants recorded affect and rumination ten times daily over six days using Ecological Momentary Assessment, after completing measures of trait ruminative brooding and habitual characteristics of negative thinking (e.g., automaticity, lack of conscious awareness, intent, and control). In study 3, formerly depressed individuals with a recurrent history of depression (n = 94) and non-clinical controls (n = 55) recorded in-the-moment affect and rumination ten times daily over six days, after completing baseline measures of trait ruminative brooding, habitual characteristics of negative thinking, and early-life stress. Results: In study 1, greater habitual characteristics of negative thinking were associated with ruminative brooding but not ruminative reflection, and predicted more persistent dysphoric mood following rumination-induction. Rumination was not, however, consistently associated with an imbalance in habit vs. goal-directed behaviour control. In study 2, momentary fluctuations in negative (increased) and positive (decreased) affect was prospectively associated with greater rumination at the next sampling occasion. The degree to which affect triggered a subsequent ruminative response was moderated by habitual characteristics of negative thinking in a theoretically consistent way. Stronger temporal pairing of negative affect and rumination was also associated with greater emotional inertia but less carry-over of rumination from one moment to the next. In study 3, momentary fluctuations in negative affect were prospectively associated with greater rumination at the next sampling occasion in formerly depressed participants whereas this pattern of mood-reactive rumination was not observed in healthy never-depressed participants. In formerly depressed participants, habitual characteristics of negative thinking were associated with greater mood-reactivity of rumination, particularly among those with a history of early-life stress. Mood-reactive rumination was not, however, associated with depression course nor trait ruminative brooding. Conclusions: The findings of the studies demonstrate that fluctuations in affect can trigger ruminative thinking as a function of habit consistent with recent theoretical frameworks of depression vulnerability. Mood-reactive rumination may be a potential vulnerability marker for depression, with rumination being habitually triggered in response to momentary fluctuations in negative affect with a high degree of automaticity, and with a deleterious effect on mood. The current thesis suggests ways depression vulnerability may emerge as a dynamic relationship between negative affect and rumination across time, not captured by traditional trait measures of rumination frequency. Ecological momentary assessment may be a valuable measurement paradigm to test predictions derived from habit-accounts of depressive rumination, that have rarely been investigated until now, and might provide new insights into research on depression risk.This research was sponsored by the Icelandic Center for Research and the Eimskip Fund of The University of Iceland (Rannís Grant 173803-052, 173803-053)

SUSTAIN drilling at Surtsey volcano, Iceland, tracks hydrothermal and microbiological interactions in basalt 50 years after eruption

The 2017 Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative concretes (SUSTAIN) drilling project at Surtsey volcano, sponsored in part by the International Continental Scientific Drilling Program (ICDP), provides precise observations of the hydrothermal, geochemical, geomagnetic, and microbiological changes that have occurred in basaltic tephra and minor intrusions since explosive and effusive eruptions produced the oceanic island in 1963–1967. Two vertically cored boreholes, to 152 and 192 m below the surface, were drilled using filtered, UV-sterilized seawater circulating fluid to minimize microbial contamination. These cores parallel a 181 m core drilled in 1979. Introductory investigations indicate changes in material properties and whole-rock compositions over the past 38 years. A Surtsey subsurface observatory installed to 181 m in one vertical borehole holds incubation experiments that monitor in situ mineralogical and microbial alteration processes at 25–124 ∘C. A third cored borehole, inclined 55∘ in a 264∘ azimuthal direction to 354 m measured depth, provides further insights into eruption processes, including the presence of a diatreme that extends at least 100 m into the seafloor beneath the Surtur crater. The SUSTAIN project provides the first time-lapse drilling record into a very young oceanic basaltic volcano over a range of temperatures, 25–141 ∘C from 1979 to 2017, and subaerial and submarine hydrothermal fluid compositions. Rigorous procedures undertaken during the drilling operation protected the sensitive environment of the Surtsey Natural Preserve

Plio-Pleistocene phylogeography of the Southeast Asian Blue Panchax killifish, Aplocheilus panchax

The complex climatic and geological history of Southeast Asia has shaped this region’s high biodiversity. In particular, sea level fluctuations associated with repeated glacial cycles during the Pleistocene both facilitated, and limited, connectivity between populations. In this study, we used data from two mitochondrial and three anonymous nuclear markers to determine whether a fresh/brackish water killifish, Aplocheilus panchax, Hamilton, 1822, could be used to further understand how climatic oscillations and associated sea level fluctuations have shaped the distribution of biota within this region, and whether such patterns show evidence of isolation within palaeodrainage basins. Our analyses revealed three major mitochondrial clades within A. panchax. The basal divergence of A. panchax mitochondrial lineages was approximately 3.5 Ma, whilst the subsequent divergence timings of these clades occurred early Pleistocene (~2.6 Ma), proceeding through the Pleistocene. Continuous phylogeographic analysis showed a clear west-east dispersal followed by rapid radiation across Southeast Asia. Individuals from Krabi, just north of the Isthmus of Kra, were more closely related to the Indian lineages, providing further evidence for a freshwater faunal disjunction at the Isthmus of Kra biogeographic barrier. Our results suggest that Sulawesi, across the Wallace Line, was colonised relatively recently (~30 ka). Nuclear DNA is less geographically structured, although Mantel tests indicated that nuclear genetic distances were correlated with geographic proximity. Overall, these results imply that recent gene flow, as opposed to historical isolation, has been the key factor determining patterns of nuclear genetic variation in A. panchax, however, some evidence of historical isolation is retained within the mitochondrial genome. Our study further validates the existence of a major biogeographic boundary at the Kra Isthmus, and also demonstrates the use of widely distributed fresh/brackishwater species in phylogeographic studies, and their ability to disperse across major marine barriers in relatively recent time periods

Foraging behaviour and brain morphology in recently emerged brook charr, Salvelinus fontinalis

Recently emerged brook charr (Salvelinus fontinalis) foraging in still-water pools along the sides of streams are either active, feeding on insects from the upper portion of the water column away from the stream bank, or sedentary, feeding on crustaceans emerging from the hyporheic zone near the stream bank. We tested whether the frequency of movement displayed by individual brook charr searching for prey in the field was related to the relative volume of the telencephalon, a brain region involved with movement and space use in fishes. Movement of individuals searching for prey was quantified in the field, individuals were captured and volumes of the telencephalon and of the olfactory bulbs, a brain region neighbouring the telencephalon but not implicated in space use, were measured. Individuals with larger telencephalon volumes moved more frequently on average while searching for prey in the field than did individuals with smaller telencephalon volumes. The frequency of movement was unrelated to differences in the volume of the olfactory bulbs, suggesting that the relationship between telencephalon volume and movement was not a consequence of differences in overall brain size. Demonstrating a correlation between foraging behaviour and brain morphology for brook charr exhibiting different foraging tactics suggests that diversification in brain structure and function could be important aspects of the foraging specialization believed to occur during early stages in the evolution and development of resource polymorphisms. © 2010 Springer-Verlag

Among-individual diet variation within a lake trout ecotype: lack of stability of niche use

In a polyphenic species, differences in resource use are expected among ecotypes, and homogeneity in resource use is expected within an ecotype. Yet, using a broad resource spectrum has been identified as a strategy for fishes living in unproductive northern environments, where food is patchily distributed and ephemeral. We investigated whether specialization of trophic resources by individuals occurred within the generalist piscivore ecotype of lake trout from Great Bear Lake, Canada, reflective of a form of diversity. Four distinct dietary patterns of resource use within this lake trout ecotype were detected from fatty acid composition, with some variation linked to spatial patterns within Great Bear Lake. Feeding habits of different groups within the ecotype were not associated with detectable morphological or genetic differentiation, suggesting that behavioral plasticity caused the trophic differences. A low level of genetic differentiation was detected between exceptionally large‐sized individuals and other piscivore individuals. We demonstrated that individual trophic specialization can occur within an ecotype inhabiting a geologically young system (8,000–10,000 yr BP), a lake that sustains high levels of phenotypic diversity of lake trout overall. The characterization of niche use among individuals, as done in this study, is necessary to understand the role that individual variation can play at the beginning of differentiation processes

Radiostereometric analysis of hemiarthroplasties of the hip – a highly precise method for measurements of cartilage wear

SummaryObjectiveCartilage wear is a feature of osteoarthritis and rheumatoid arthritis. Precise measurements of wear have been difficult. Cartilage wear caused by an artificial articulating joint surface is a well-known feature of hemiarthroplasties. The aim of this study was to demonstrate that radiostereometric analysis (RSA) may be used for three-dimensional measurements of cartilage wear in hemiarthroplasties of the hip.MethodWe performed a phantom model study to assess the feasibility of a subsequent clinical trial. We showed that the motion of the prosthetic head relative to the pelvis was not influenced by the orientation of the prosthetic head. Twenty-two patients were randomised to treatment with a cemented or an uncemented hemiarthroplasty for an acute femoral neck fracture. Migration of the prosthetic head into the acetabulum was measured using RSA.ResultsA mean migration of the prosthetic head into the acetabulum of 0.62 mm was found at 3 months [95% confidence interval (CI): 0.27–0.97] and a further migration of −0.07 mm at 12 months (95% CI: −0.16–0.32). There were no differences between the groups in prosthetic migration or functional outcome. Between three and 12 months, there was no detectable cartilage wear during the first postoperative year.ConclusionWhether the migration during the first 3 months represents a period of bedding in due to a harder opposite surface remains to be shown. RSA may be used for measurement of cartilage wear in hemiarthroplasties of the hip. This study demonstrates a highly precise method for measurements of cartilage wear