Temporally Persistent Research Articles

Decoding Cortical Chronotopy - Comparing the Influence of Different Cortical Organizational Schemes

The brain's diverse intrinsic timescales enable us to perceive stimuli with varying temporal persistency. This study aimed to uncover the cortical organizational schemes underlying these variations, revealing the neural architecture for processing a wide range of sensory experiences. We collected resting-state fMRI, task-fMRI, and diffusion-weighted imaging data from 47 individuals. Based on this data, we extracted six organizational schemes: (1) the structural Rich Club (RC) architecture, shown to synchronize the connectome; (2) the structural Diverse Club architecture, as an alternative to the RC based on the network's module structure; (3) the functional uni-to-multimodal gradient, reflected in a wide range of structural and functional features; and (4) the spatial posterior/lateral-to-anterior/medial gradient, established for hierarchical levels of cognitive control. Also, we explored the effects of (5) structural graph theoretical measures of centrality and (6) cytoarchitectural differences. Using Bayesian model comparison, we contrasted the impact of these organizational schemes on (1) intrinsic resting-state timescales and (2) inter-subject correlation (ISC) from a task involving hierarchically nested digit sequences. As expected, resting-state timescales were slower in structural network hubs, hierarchically higher areas defined by the functional and spatial gradients, and thicker cortical regions. ISC analysis demonstrated hints for the engagement of higher cortical areas with more temporally persistent stimuli. Finally, the model comparison identified the uni-to-multimodal gradient as the best organizational scheme for explaining the chronotopy in both task and rest. Future research should explore the microarchitectural features that shape this gradient, elucidating how our brain adapts and evolves across different modes of processing.

Spatio-Temporal Assessment of the European Hake (Merluccius merluccius) Recruits in the Northern Iberian Peninsula

The protection of fish nurseries has been recognized as a useful tool to efficiently manage fisheries given that protected areas enhance the recruitment of target species. To identify and locate potential nursery areas, a solid understanding of species-environment relationships and their spatio-temporal dynamics is needed. Within this context, in this study we assess where European hake (Merluccius merluccius) recruits persistently aggregate in the northern continental shelf of the Iberian Peninsula. Hake recruit data collected during scientific trawl surveys between 2005 and 2016 were analyzed using Bayesian hurdle hierarchical spatio-temporal models, considering the environmental variables bathymetry, sea bottom temperature and salinity. Additionally, three different spatio-temporal structures (i.e., persistent, progressive, or opportunistic) were compared to assess the temporal persistence of nurseries over time. Among all the environmental variables analyzed, bathymetry was the most important. The preferential habitat of recruits was found to be within a bathymetric range of 120–200 m. Our findings clearly show that there is a temporally persistent main nursery located along the continental shelf of the Artabrian gulf (off La Coruña) in addition to several areas with high aggregations of hake recruits but with strong inter-annual variability. We argue that the analytical framework applied in this study allowed us to identify European hake nurseries in the northern continental shelf of the Iberian Peninsula, as well as their spatio-temporal fluctuations throughout the study period (2005–2016), and to assess which environmental factors, among bathymetry, sea bottom temperature and salinity, influence the occurrence and abundance of recruits in the study area. Results of our models also produce a new abundance index that could be useful for improving traditional stock assessment models.

Biofeedback augmenting lower limb loading alters the underlying temporal structure of gait following anterior cruciate ligament reconstruction.

Biofeedback has recently been explored to target deviant lower extremity loading mechanics following anterior cruciate ligament reconstruction (ACLR) to mitigate the development of post traumatic osteoarthritis. The impact this feedback has on the structure of the stride interval dynamics-a barometer of gait system health-however, have yet to be examined. This study was designed to assess how feedback, used to alter lower-extremity loading during gait, affects the structure of stride interval variability by examining long-range stride-to-stride correlations during gait in those with unilateral ACLR. Twelve participants walked under three separate loading conditions: (1) control (i.e., no cue) (2) high loading, and (3) low loading. Baseline vertical ground reaction force (vGRF) data was used to calculate a target 5% change in vGRF for the appropriate loading condition (i.e., high loading was +5% vGRF, low loading was -5% vGRF). The target for the load condition was displayed on a screen along with real-time vGRF values, prescribing changes in stride-to-stride peak vertical ground reaction forces of each limb. From time-series of stride intervals (i.e., duration), we analyzed the mean and standard deviation of stride-to-stride variability and, via detrended fluctuation analysis (i.e., DFA α), temporal persistence for each feedback condition. Both the high and low loading conditions exhibited a change toward more temporally persistent stride intervals (high loading: α =0.92, low loading: α=0.98) than walking under the control condition (α=0.78; high vs. control: p=.026, low vs. control: p=.001). Overall, these results indicate that altering lower extremity load changes the temporal persistence of the stride internal dynamics in ACLR individuals, demonstrating the implications of the design of gait training interventions and the influence feedback has on movement strategies.

Why Temporal Persistence of Biometric Features, as Assessed by the Intraclass Correlation Coefficient, Is So Valuable for Classification Performance.

It is generally accepted that relatively more permanent (i.e., more temporally persistent) traits are more valuable for biometric performance than less permanent traits. Although this finding is intuitive, there is no current work identifying exactly where in the biometric analysis temporal persistence makes a difference. In this paper, we answer this question. In a recent report, we introduced the intraclass correlation coefficient (ICC) as an index of temporal persistence for such features. Here, we present a novel approach using synthetic features to study which aspects of a biometric identification study are influenced by the temporal persistence of features. What we show is that using more temporally persistent features produces effects on the similarity score distributions that explain why this quality is so key to biometric performance. The results identified with the synthetic data are largely reinforced by an analysis of two datasets, one based on eye-movements and one based on gait. There was one difference between the synthetic and real data, related to the intercorrelation of features in real data. Removing these intercorrelations for real datasets with a decorrelation step produced results which were very similar to that obtained with synthetic features.

Temporal persistence of intra-urban spatial contrasts in ambient NO2, O3 and Ox in Edinburgh, UK

Ambient NO2, O3 and Ox (the sum of NO2 and O3) are associated with adverse health outcomes. Quantitative assessment of the health burden from these pollutants requires knowledge of small-scale variations in their concentrations in urban environments. In particular, we were interested in the temporal stability of intra-urban spatial contrasts in these pollutants. This was investigated by concurrent measurements of NO2 and O3 by passive samplers at 30 sites in Edinburgh, UK, repeated 12 × 1-weekly for NO2 and 6 × 2-weekly for O3 in summer and winter. Temporally persistent and large spatial variations in both NO2 and O3 concentrations were observed. Concentrations of NO2 across the sites ranged on average by a factor of 14 between suburban parks and heavily-trafficked roadsides, corresponding to a difference in NO2 on average of ∼80 μg m−3. Intra-urban O3 concentrations also varied substantially, on average by a factor of 4 (average range 45 μg m−3) and with strong anticorrelation to NO2 concentrations across the 30 sites. Consequently intra-urban variability was considerably lower for Ox than for NO2 and O3. The temporal stability in relative NO2 and O3 concentrations indicate potential for deriving intra-urban spatial fields of NO2 and O3 at different times by scaling models of long-term spatial patterns of NO2 and O3 by the measurements at a single site. If Ox is a key determinant of adverse health then the large intra-urban spatial contrasts in NO2 and O3 may be less relevant, with Ox concentrations across an urban area determined at a suitable background site.

Using life history trade‐offs to understand core‐transient structuring of a small mammal community

An emerging conceptual framework suggests that communities are composed of two main groups of species through time: core species that are temporally persistent, and transient species that are temporally intermittent. Core and transient species have been shown to differ in spatiotemporal turnover, diversity patterns, and importantly, survival strategies targeted at local versus regional habitat use. While the core‐transient framework has typically been a site‐specific designation for species, we suggest that if core and transient species have local versus regional survival strategies across sites, and consistently differ in population‐level spatial structure and gene flow, they may also typically exhibit different life‐history strategies. Specifically, core species should display relatively low movement rates, low reproductive effort, high ecological specialization and high survival rates compared to transient species, which may display a wider range of traits given that transience may result from source‐sink dynamics or from the ability to emigrate readily in a nomadic fashion. We present results from 21 years of capture‐mark‐recapture data in a diverse rodent community, evaluating the linkages between temporal persistence, local abundance, and trade‐offs among life‐history traits. Core species at our site conservatively supported our hypotheses, differing in ecological specialization, survival and movement probabilities, and reproductive effort relative to transient species. Transient species exhibited a wider range of characteristics, which likely stems from the multiple processes generating transience in local communities, such as source‐sink dynamics at larger regional scales or nomadic life history strategies. We suggest that trait associations among core‐transient species may be similar in other systems and warrants further study.

Temporal dynamics of direct reciprocal and indirect effects in a host–parasite network

1. Temporal variation in the direct and indirect influence that hosts and parasites exert on each other is still poorly understood. However, variation in species' influence due to species and interactions turnover can have important consequences for host community dynamics and/or for parasite transmission dynamics, and eventually for the risk of zoonotic diseases. 2. We used data on a network of small mammals and their ectoparasites surveyed over 6 years to test hypotheses exploring (i) the temporal variability in direct and indirect influences species exert on each other in a community, and (ii) the differences in temporal variability of direct/indirect influences between temporally persistent (TP) and temporally intermittent species. 3. We modelled the temporal variation in (i) direct reciprocal influence between hosts and parasites (hosts providing resources to parasites and parasites exploiting the resources of hosts), using an asymmetry index, and (ii) indirect influence among species within a community (e.g. facilitation of parasite infestation by other parasites), using betweenness centrality. We also correlated asymmetry and centrality to examine the relationship between them. 4. Network dynamics was determined by TP species but even those species had strong among-species heterogeneity in the temporal variation of the direct/indirect effects they exerted. In addition, there was a significant positive linear correlation between asymmetry and centrality. 5. We conclude that the temporal dynamics of host-parasite interactions is driven by TP hosts. However, even within this group of persistent species, some exhibit large temporal variation, such that the functional roles they play (e.g. in promoting parasite transmission) change over time. In addition, parasites having a large negative impact on hosts are also those facilitating the spread of other parasites through the entire host community. Our results provide new insights into community dynamics and can be applied in the management of antagonistic networks aimed at preventing disease outbreaks.

Chapter 4 Global distributional dynamics of Cambrian clades as revealed by Burgess Shale-type deposits

Abstract The Cambrian geographical and temporal distributions of many clades remain poorly understood, despite their importance for elucidating the palaeobiogeographical context of the Cambrian radiation. New species and genus level occurrence databases were developed to analyse temporal and geographical distributional patterns in taxa belonging to 14 clades from over 60 globally distributed early and Middle Cambrian Burgess Shale-type lagerstätten. Analyses demonstrate that clades with confirmed Precambrian origins were, on average, more widespread and temporally persistent than clades with first fossil occurrences in the Cambrian. Despite their dominance in diversity, arthropods were less widely distributed and temporally persistent than many other groups. Finally, a significant correlation between geographical range and temporal persistence is demonstrated, supporting the hypothesis that Cambrian taxa with wider geographical ranges were less likely to go extinct than those with narrower ranges. Supplementary material: Species and genus data tables are available at: http://www.geolsoc.org.uk/SUP18665

Changing controls of soil moisture spatial organization in the Shale Hills Catchment

Modeling hydrological processes often requires the identification of dominant controls on soil moisture spatial organization under different climatic conditions at various soil depths. In this study, we utilized a four-year database consisting of soil moisture measurements at 106 locations from near-surface down to 1.1m depth across a forested catchment in central Pennsylvania, USA. Our objectives were to 1) compare the spatial organization of soil moisture within different soil–landform units and its temporal persistence at different depths under varying catchment wetness conditions and 2) investigate correlation strength between soil moisture content and 11 soil–terrain attributes and the temporal change of such correlation. Our results showed that the catchment's near-surface (<0.3m) soil moisture organization exhibited clear seasonal trends: during winter through early summer, areas of high soil moisture were concentrated within convergent landforms; while during summer through early fall, soil moisture was more uniformly distributed throughout this complex terrain catchment. This suggests that under dry conditions soil moisture removal (primarily through evapotranspiration) had a significant influence on the organization of near-surface soil moisture, while topography was an important control on soil moisture spatial organization under wet conditions. Subsurface (>0.3 to 1.1m) soil moisture organization, however, exhibited increasing temporal persistence with depth, and subsoil moisture above the catchment-wide average was concentrated within convergent landforms under both wet and dry conditions. Topographic wetness index, slope, depth to bedrock, and percent (by weight) clay and rock fragment were significant (p<0.05) factors influencing soil moisture content on at least 80% of 91 measurement days analyzed for all soil depths. Intermediate depths (>0.3 to <0.7m) exhibited the highest coefficient of determination (R2) in linear regression for topographic wetness index, suggesting that lateral subsurface flow may be an important driver of soil moisture dynamics at these depths in this catchment. Mean R2 values for slope, depth to bedrock, and percent clay and rock fragment increased with increasing depth, confirming the importance of deep soil moisture storage on subsoil moisture organization. We conclude that the controls on this catchment's soil moisture spatial organization at the near-surface (<0.3m) fluctuates seasonally between evapotranspiration and topography; that at intermediate depths (0.3 to 0.7m) the soil moisture organization is controlled significantly by lateral subsurface flow; and that the organization at deeper depths (>0.7m) becomes more temporally persistent and is primarily a function of both topography and soil depth.

Applying Methods from Differential Geometry to Devise Stable and Persistent Air Layers Attached to Objects Immersed in Water

We describe a few mathematical tools which allow to investigate whether air-water interfaces exist (under prescribed conditions) and are mechanically stable and temporally persistent. In terms of physics, air-water interfaces are governed by the Young-Laplace equation. Mathematically they are surfaces of constant mean curvature which represent solutions of a nonlinear elliptic partial differential equation. Although explicit solutions of this equation can be obtained only in very special cases, it is – under moderately special circumstances – possible to establish the existence of a solution without actually solving the differential equation. We also derive criteria for mechanical stability and temporal persistence of an air layer. Furthermore we calculate the lifetime of a non-persistent air layer. Finally, we apply these tools to two examples which exhibit the symmetries of 2D lattices. These examples can be viewed as abstractions of the biological model represented by the aquatic fern Salvinia.

Effects of temporally persistent ant nests on soil protozoan communities and the abundance of morphological types of amoeba

We compared soil protozoan communities near ant nests with soil protozoans in reference soils 5 m from the edge of ant mounds. We sampled three species of Chihuahuan Desert ants that construct nests that persist for more than a decade: a seed harvester, Pogonomyrmex rugosus, a liquid feeding honey-pot ant, Myrmecocystus depilis, and a generalist forager, Aphaenogaster cockerelli. Ant colonies were located on different topographic positions on catenas of two watersheds. Total protozoan abundance was higher in P. rugosus nest soils at the top of a catena and in A. cockerelli nest soils in a grassland than in the respective reference soils. There were qualitative and quantitative differences in protozoan communities associated with the nests of ants at all locations studied. Amoebae were the most abundant protozoans at all locations. Type 1 amoebae (flattened with sub-pseudopodia (like Acanthamoeba)) occurred at the highest frequency and was the only amoeba type found in M. depilis nest soils and P. rugosus nest soils at the top of a catena. Nanoflagellates were associated with P. rugosus and M. depilis nest soils but were absent from reference soils. Ciliates, testate amoebae and nanoflagellates were absent from A. cockerelli reference soils but were present in nest soils. The effects of ants on soil protozoan communities depend on the temporal persistence of the colony, nest building and food handling behavior, topographic position and soil type.

Empirical Mode Decomposition in 2-D space and time: a tool for space-time rainfall analysis and nowcasting

Abstract. A data-driven method for extracting temporally persistent information, at different spatial scales, from rainfall data (as measured by radar/satellite) is described, which extends the Empirical Mode Decomposition (EMD) algorithm into two dimensions. The EMD technique is used here to decompose spatial rainfall data into a sequence of high through to low frequency components. This process is equivalent to the application of successive low-pass spatial filters, but based on the observed properties of the data rather than the predetermined basis functions used in traditional Fourier or Wavelet decompositions. It has been suggested in the literature that the lower frequency components (those with large spatial extent) of spatial rainfall data exhibit greater temporal persistence than the higher frequency ones. This idea is explored here in the context of Empirical Mode Decomposition. The paper focuses on the implementation and development of the two-dimensional extension to the EMD algorithm and it's application to radar rainfall data, as well as examining temporal persistence in the data at different spatial scales.

Application of a Temporal Persistence Model to Community Residents' L]ong‐Term Beliefs about the Three Mile island Nuclear Accident1

Little is known about the conditions under which beliefs and attitudes about an issue or event will persist over time. The present research took advantage of a “natural experiment”, namely, the Three Mile Island (TMI) nuclear accident, in order (a) better to understand the nature of individuals' b]eliefs about a major event to which they were exposed and (b) to evaluate a conceptual formulation developed from laboratory‐based experimental literature concerning when beliefs and attitudes are likely to be temporally persistent. Data were collected over a 3‐year period following the accident from two samples of community residents: mothers of young children who lived within a 10‐mile radius of TMI and TMI nuclear power plant employees. Samples of mothers and workers from a western Pennsylvania comparison site were also included in the study design. Results supported the persistence model in several respects. First, TMI subjects' b]eliefs, although more extreme than comparison subjects' v]iews, showed virtually no change during the study period. Second, the factors that the model suggests should account for the observed persistence were indeed consistently important predictors of TMI subjects' b]eliefs over time. Implications of the results for future applied work on long‐term reactions to major events are discussed.