Synchronization Patterns Research Articles

Local- and Regional-Scale Climate Variability Drives Complex Patterns of Growth Synchrony and Asynchrony in Deep-Sea Snappers Across the Indo-Pacific.

Climatic variation can play a critical role in driving synchronous and asynchronous patterns in the expression of life history characteristics across vast spatiotemporal scales. The synchronisation of traits, such as an individual's growth rate, under environmental stress may indicate a loss of phenotypic diversity and thus increased population vulnerability to stochastic deleterious events. In contrast, synchronous growth under favourable ecological conditions and asynchrony during unfavourable conditions may help population resilience and buffer against the negative implications of future environmental variability. Despite the significant implications of growth synchrony and asynchrony to population productivity and persistence, little is known about its causes and consequences either within or among fish populations. This is especially true for long-lived deep-sea species that inhabit environments characterised by large-scale interannual and decadal changes, which could propagate growth synchrony across vast distances. We developed otolith growth chronologies for three deep-sea fishes (Etelis spp.) over 65° of longitude and 20° of latitude across the Indo-Pacific region. Using reconstructed time series of interannual growth from six distinct Exclusive Economic Zones (EEZs), we assessed the level of spatial synchrony at the individual-, population- and species-scale. Across five decades of data, complex patterns of synchronous and asynchronous growth were apparent for adult populations within and among EEZs of the Pacific Ocean, mediated by shifts in oceanographic phenomena such as the Pacific Decadal Oscillation. Overall, our results indicate that the degree of synchrony in biological traits at depth depends on life history stage, spatiotemporal scales of environmental variability and the influence of ecological factors such as competition and dispersal. By determining the magnitude and timing of spatially synchronous growth at depth and its links to environmental variability, we can better understand fluctuations in deep-sea productivity and its vulnerability to future environmental stressors, which are key considerations for sustainability.

Localized synchronous patterns in weakly coupled bistable oscillator systems

Localized synchronous patterns in weakly coupled bistable oscillator systems

Rock Glacier Velocity: An Essential Climate Variable Quantity for Permafrost

AbstractRock glaciers are distinctive debris landforms found worldwide in cold mountainous regions. They express the long‐term movement of perennially frozen ground. Rock Glacier Velocity (RGV), defined as the time series of the annualized surface velocity of a rock glacier unit or a part of it, has been accepted as an Essential Climate Variable Permafrost Quantity in 2022. This review aims to highlight the relationship between rock glacier velocity and climatic factors, emphasizing the scientific relevance of interannual rock glacier velocity in generating RGV products within the context of observed rock glacier kinematics. Under global warming, rock glacier velocity exhibits widespread (multi‐)decennial acceleration. This acceleration varies regionally in onset timing (from the 1950s to the 2010s) and magnitude (up to a factor of 10), and has been observed in regions such as the European Alps, High Mountain Asia, and the Andes. Despite different local conditions, a synchronous interannual velocity pattern prevails in the European Alps since the 2000s, highlighting the primary influence of climate. A common pattern is the seasonal velocity rhythm, which peaks in late summer to autumn and declines in spring. RGV assesses permafrost evolution via (multi‐)decennial and interannual changes in rock glacier velocity, influenced by air temperature shifts with varying time lags and snow cover effects. Although not integrated into the RGV products, seasonal variations should be examined. This rhythmic behavior is attributed to alterations in pore water pressure influenced by air temperature, snow cover, and ground water conditions.

Developmental synchrony and extraordinary multiplication rates in pathogenic organisms.

The multiplication rates of pathogenic organisms influence disease progression, efficacy of immunity and therapeutics, and potential for within-host evolution. Thus, accurate estimates of multiplication rates are essential for biological understanding. We recently showed that common methods for inferring multiplication rates from malaria infection data substantially overestimate true values (i.e. under simulated scenarios), providing context for extraordinarily large estimates in human malaria parasites. A key unknown is whether this bias arises specifically from malaria parasite biology or represents a broader concern. Here, we identify the potential for biased multiplication rate estimates across pathogenic organisms with different developmental biology by generalizing a within-host malaria model. We find that diverse patterns of developmental sampling bias-the change in detectability over developmental age-reliably generate overestimates of the fold change in abundance, obscuring not just true growth rates but potentially even whether populations are expanding or declining. This pattern emerges whenever synchrony-the degree to which development is synchronized across the population of pathogenic organisms comprising an infection-decays with time. Only with simulated increases in synchrony do we find noticeable underestimates of multiplication rates. Obtaining robust estimates of multiplication rates may require accounting for diverse patterns of synchrony in pathogenic organisms.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

Emotional Influences on Remembering and Forgetting Explained by Frontal and Parietal Dynamics.

Based on item-method directed forgetting (DF) task, sixty participants were recruited to explore the influence of emotion (negative, neutral, and positive) on memory encoding processing. Behavioral results showed that participants were more successful at remembering negative pictures that needed to be forgotten, with both higher recognition rates and Pr values compared to neutral pictures. In the brain, parietal activities reflected preferential processing during negative picture viewing through enhanced late parietal positive potentials (LPP) relative to neutral ones. In addition, 'Remember' (R) instruction evoked a larger parietal P3 component, whereas 'Forget' (F) instruction evoked a stronger frontal N2 component, each of which component was significantly associated with the DF effect (i.e., more recognized items of R-cue than that of F-cue), reflecting the fact that inhibitory control and selective rehearsal mechanisms were jointly responsible for the directed forgetting of emotional materials. Finally, we showed the presence of instruction-evoked low-frequency phase synchronization between frontal and parietal regions, and that these synchronization patterns differed between R-cue and F-cue in an emotion-dependent manner. Together, these findings reveal cognitive mechanisms and specific patterns of large-scale phase synchronization underlying active forgetting of emotional memories, deepening our comprehension into the interplay between cognition and emotion.

Synchrony dynamics of dissolved organic carbon in high‐mountain streams: Insights into scale‐dependent processes

AbstractIn high‐mountain landscapes, organic carbon (OC) is often limited and heterogeneously stored in poorly developed soils, snow, ground ice, and glaciers. Climate change influences the dynamics of OC mobilization to—and processing into—the recipient streams. Dynamics vary from seasonal (e.g., snow melt in spring) to daily (e.g., ice melt in summer) depending on the location of the streams within the catchment. Capturing the temporal richness of stream biogeochemical signals has become a reality with the advent of high‐resolution sensors. In this study, we applied wavelet analysis to high‐frequency discharge (Q) and dissolved organic carbon (DOC) measurements from nine streams in the Swiss Alps to investigate the persistence of synchrony in Q (SQ) and DOC (SDOC) among streams, and their response to drainage network position, climate, and land cover gradients across different time scales. Our findings revealed that SQ and SDOC decayed non‐linearly over the first ~ 5 km and stabilized from this point onwards, indicating that localized controls influenced synchrony within single basins, but drivers operating at regional scale acted as synchrony stabilizers. We also showed that short‐term (0–10 d) SQ and SDOC were strongly influenced by the distance between streams and network connectivity. In contrast, catchment‐related properties (i.e., altitude or land cover) were more important drivers of SQ and SDOC dynamics at longer time scales (> 50 d). However, the degree to which local catchment properties controlled synchrony patterns at the longest timescales depended both on response variables (i.e., Q vs. DOC) and land cover (i.e., vegetation vs. glacier). Elucidating the most prominent timescales of SDOC is relevant given the hydrological alterations projected for high‐mountain regions. We show that glaciers impose a unique seasonal regime on DOC concentration, potentially overriding the effects of other local hydrological or biogeochemical processes during downstream transport. Consequently, SDOC dynamics in high‐mountain streams may change as glaciers shrink, thereby altering downstream opportunities for biogeochemical transformations.

Is temporal synchrony necessary for effective Batesian mimicry?

Batesian mimicry occurs when palatable mimics gain protection from predators by evolving a phenotypic resemblance to an aposematic model species. While common in nature, the mechanisms maintaining mimicry are not fully understood. Patterns of temporal synchrony (i.e. temporal co-occurrence) and model first occurrence have been observed in several mimicry systems, but the hypothesis that predator foraging decisions can drive the evolution of prey phenology has not been experimentally tested. Here, using phenotypically accurate butterfly replicas, we measured predation rates on the chemically defended model species Battus philenor and its imperfect Batesian mimic Limenitis arthemis astyanax under four different phenological conditions to understand the importance of temporal synchrony and model first occurrence in mimicry complexes. We predicted that protection for mimics increases when predators learn to avoid the models' aposematic signal right before encountering the mimic, and that learned avoidance breaks down over time in the model's absence. Surprisingly, we found that asynchronous model first occurrence, even on short time scales, did not provide increased protection for mimics. Mimics were only protected under conditions of temporal synchrony, suggesting that predators rely on current information, not previously learned information, when making foraging decisions.

Distribution of Tunisian beet wild relatives (Beta sp.) according to morphological characteristics and eco-geographical origin.

Beta vulgaris subsp. maritima (L.) Arcang. and Beta macrocarpa Guss. are crop wild relative taxa belonging to the primary gene pool. They constitute a crucial gene reserve for enhancing cultivated Beta species (B. vulgaris subsp. vulgaris L.). Climate change poses a significant threat to genetic reservoir in Tunisia. We evaluated the morphological diversity of ten populations of B. vulgaris subsp. maritima and five populations of B. macrocarpa growing in different Tunisian bioclimatic and ecological areas using a set of 9 quantitative and 14 qualitative traits to promote the preservation and exploration of this germplasm. Variance component analysis of the quantitative data showed an important spectrum of variability, both within and between populations. The principal component analysis (PCA) allocated this wild Beta collection into three groups. G1 included the populations of B. macrocarpa that were characterized by the largest glomerules and heaviest seeds, while G2 included all B. vulgaris subsp. maritima populations except one, i.e., N1015 that clustered into G3, which was characterized by the highest values of leaf characters. Similarly, qualitative traits exhibited a high diversity level (H'index ≥0.6) for almost all characters. The PCA divided these 15 populations into three groups as well: G'1 concerned the island B. vulgaris subsp. maritima populations, characterized by prostrate growth habit and red inflorescences; G'2 included all B. macrocarpa populations characterized by erect-procumbent growth habit and very synchronous flowering pattern; and G'3 was formed by the mainland B. vulgaris subsp. maritima populations, characterized by erect growth habit and hairy, curly leaves. The observed eco-geographic distribution patterns suggest that these wild relatives are highly adaptable to diverse and even extreme conditions (salinity, heat, and drought), highlighting their potential as resilient gene sources for beet breeding under the challenges of accelerating climate change.

Stop-Lateral Clusters in French and Spanish: Articulatory Timing Differences and Synchronic Patterns

While both French and Spanish have complex onsets, the languages differ in the variety and distribution of clusters allowed as well as in the realization of voiced stops. The present study examines the effects of C1 voicing, place of articulation, and language on the production of word-initial /pl bl kl gl/ using a combination of electropalatographic (C1 and C2 linguopalatal contact and timing) and acoustic measures (duration and relative intensity) from 4 French and 7 Spanish speakers. Certain between-language similarities and differences in the effects of voicing and place on intergestural timing were observed. In particular, (1) both languages showed more overlap in clusters where C1 was velar rather than labial; (2) the effect of voicing (more overlap in clusters with a voiced C1) was restricted to French; and (3) lateral duration was unaffected by C1 place or voicing, while C1 duration was strongly affected by stress and voicing in Spanish alone given the approximantization of voiced stops. These results contribute to a better understanding of the general mechanisms and language-specific patterns of intergestural coordination in onset clusters and add to the growing body of articulatory work on these complex structures in Romance languages.

A diachronic account of Present Day Standard Danish stop gradation

Abstract In certain contexts, Present Day Standard Danish displays an unusual pattern of alternations between voiceless stops and semivowels often referred to as stop gradation. Stop gradation is traditionally considered a synchronic phonological process, but evidence for this analysis is based almost exclusively on non-productive morphology. Here, we argue that the structural generalization captured by a synchronic analysis is better accounted for with reference to the history of Danish, and to well-understood constraints on articulation and perception which led to prosodically conditioned chain shifts and mergers through gradual, continuous changes in the realization of consonant allophones. Inspired by the change-chance-choice model of sound change in Evolutionary Phonology, we outline the historical trajectory that led to the synchronic stop gradation patterns, and the well-known phonetic pressures underlying them; these pressures pulled the allophone distributions of stops in different prosodic contexts in very different directions.

Prognostic significance of lymph node metastasis of soft tissue sarcoma of the extremities. National cancer institute experience.

Lymph node metastasis (LNM) in soft tissue sarcoma (STS) of the extremities is relatively rare. We aimed to evaluate the prognosis and the survival of patients with LNM and correlate them to the pattern of metastasis. A retrospective study of patients diagnosed with STS of the extremities from 2015 to 2019. 111/1506 patients (7.4%) had LNM. Nodal metastasis was correlated significantly with old age, advanced tumor stages, high-grade tumors, presence of Lymphovascular invasion (LVI), and resection margins < = 2cm. Metachronous LNM was documented in 96 patients (86.5%) and synchronous LNM in 15 patients (13.5%). The 6-year overall survival (OS) was 36.3% for those with LNM and 52.9% for those without LNM. The 6-year disease-free survival (DFS) was 5.7% for those with LNM and 32.6% for those without LNM. Metachronus pattern of LNM showed a significantly poorer outcome regarding 6-year OS and DFS than the synchronous pattern. LNM significantly negatively predicts OS and DFS in the extremities' STS. In particular, the metachronous pattern of LNM indicates a grave prognosis as these patients are supposed to harbor an occult LNM at presentation and were not subjected to lymphadenectomy at their initial primary treatment surgery. Therefore, seeking a valid noninvasive diagnostic tool such as sentinel lymph node biopsy to detect nodal metastasis is necessary.

From behavioral synchrony to language and beyond.

Decades of research on joint attention, coordinated joint engagement, and social contingency identify caregiver-child interaction in infancy as a foundation for language. These patterns of early behavioral synchrony contribute to the structure and connectivity of the brain in the temporoparietal regions typically associated with language skills. Thus, children attune to their communication partner and subsequently build cognitive skills directly relating to comprehension and production of language, literacy skills, and beyond. This has yielded marked interest in measuring this contingent, synchronous social behavior neurally. Neurological measures of early social interactions between caregiver and child have become a hotbed for research. In this paper, we review that research and suggest that these early neural couplings between adults and children lay the foundation for a broader cognitive system that includes attention, problem solving, and executive function skills. This review describes the role of behavioral synchrony in language development, asks what the relationship is between neural synchrony and language growth, and how neural synchrony may play a role in the development of a broader cognitive system founded in a socially-gated brain. We address the known neural correlates of these processes with an emphasis on work that examines the tight temporal contingency between communicative partners during these rich social interactions, with a focus on EEG and fNIRS and brief survey of MRI and MEG.

Network structure and time delays shape synchronization patterns in brain network models.

In this paper, we investigate synchronization patterns and coherence for a network of delayed Wilson-Cowan nodes. To capture information processing across different brain regions, our model incorporates two distinct delays: an intra-nodal delay that reflects the time signals take to travel within a cortical region due to local circuitry and an inter-nodal delay representing the longer communication times associated with white matter connections between brain areas. To investigate the role of network topology, we consider a range of toy network structures as well as the known (macro-scale) cortical structure of the Macaque monkey. We examine how global network dynamics are shaped by a combination of network configuration, coupling strength, and time delays. Our focus lies on two dynamic measures: synchrony and metastability, the latter reflecting the temporal variation of the former, both crucial for the brain's real-time functionality. Our investigation identifies extensive regions within the system's parameter space where the synchronized state exhibits transverse instabilities. These instabilities give rise to diverse dynamical behaviors contingent upon the network architecture and the interplay between coupling strength and time delay. While similar complex partially synchronized states existed for all network topologies considered, the cortical network demonstrated time-dependent behaviors, such as phase cluster dynamics, which were absent in the toy network architectures, and which are considered crucial in its ability to orchestrate complex information processing and behavior. Additionally, we illustrate how delays can regulate a cortical network with chaotic local dynamics, thus emphasizing the potential importance of delays in suppressing pathological spreading dynamics.

Investigating covert awareness in individuals with Alzheimer’s Disease using functional near‐infrared spectroscopy (fNIRS)

AbstractBackgroundAlzheimer’s disease (AD) is a form of dementia that impairs memory, language, and daily functioning. With disease progression, AD patients reportedly experience disturbances in their awareness of self, others, and their environment. These disturbances are associated with unfavourable clinical outcomes, which prompts critical questions about how AD patients experience the world around them. The present study utilizes a validated neuroimaging paradigm to ‘map’ conscious experiences through changes in brain activity. The premise is that similarity (i.e., synchrony) in conscious experiences of different people can be detected by investigating activity in fronto‐parietal areas linked with higher‐order processing essential for plot‐following. This paradigm was previously used to assess conscious states of behaviorally non‐responsive brain‐injured patients, showing that the internal mental experience of some patients was similar to that of healthy controls.MethodsIn this study, patients with mild‐moderate AD (n = 9) and age‐matched healthy controls (n = 29) underwent a 40‐minute functional near‐infrared spectroscopy (fNIRS) scan. During the scan, participants watched two short movies, each with an intact‐ and scrambled‐plot version. Scrambled versions were included to demonstrate that synchrony was associated with higher‐order processing rather than the mere presentation of audio‐visual stimuli. Inter‐subject correlations (i.e., Pearson correlation coefficients between the hemodynamic activity of one or more AD patients and the remaining participants, including healthy controls) were used as the metric for synchrony.ResultsCompared to the scrambled plot conditions, healthy controls showed robust synchronization in the frontal and parietal regions in the intact‐plot conditions. AD patients, in contrast, did not demonstrate a consistent pattern of synchronization in these regions during the intact‐plot conditions. Single‐subject analyses (i.e., comparing individual patients to the control group) further revealed that only one AD patient exhibited some degree of synchronization with the healthy controls during the audio‐visual stimuli.ConclusionThese preliminary findings indicate that AD patients may be experiencing the world differently from healthy individuals. The variability noted in synchronization across AD patients may be reflective of the heterogeneity in disease‐related impairments. Understanding deficits and patient needs from the lens of impaired conscious processing could support disease prognosis and promote improvements in person‐centered care.

Synchronization of E. coli Bacteria Moving in Coupled Microwells.

Synchronization plays a crucial role in the dynamics of living organisms. Uncovering the mechanism behind it requires an understanding of individual biological oscillators and the coupling forces between them. Here, a single-cell assay is developed that studies rhythmic behavior in the motility of E.coli cells that can be mutually synchronized. Circular microcavities are used to isolate E.coli cells that swim along the cavity wall, resulting in self-sustained oscillations. Connecting these cavities by microchannels yields synchronization patterns with phase slips. It is demonstrated that the coordinated movement observed in coupled E.coli oscillators follows mathematical rules of synchronization which is used to quantify the coupling strength. These findings advance the understanding of motility in confinement, and open up new opportunities for engineering networks of coupled oscillators in microbial activematter.

The Alignment of Internal and External Audit Agencies in Administering Public Sector Audits in Indonesia

The management of public finance to achieve national prosperity requires the effective, efficient, and integrated work of the existing audit boards. Therefore, continuous evaluation of the alignment of internal and external audit agencies is essential to ensure reliable public financial management and prevent corruption. This study describes the performance and coordination patterns between internal and external audit agencies by detailing their synchronization patterns in administering financial audits in the Indonesian public sector. Using a normative legal research method, the study incorporates legislative and conceptual approaches. The findings reveal that the performance of both internal and external audit agencies in safeguarding public finance from fraud shows varied degrees of effectiveness. However, a comprehensive regulatory framework governing the alignment of these agencies remains absent. Furthermore, synchronization in public finance audits is pursued through a unified regulatory framework, horizontal alignment among agencies, and the establishment of clear boundaries of authority and coordination mechanisms between the internal and external audit agencies. Further research should consider the potential for consolidating various regulations of public sector audits through an omnibus law approach.

The slow clock is the master

AbstractWe investigate the synchronization and stability of mutually coupled oscillators through small impacts and explore both master–master and master–slave synchrony. The synchronization behaviour between two oscillators, one operating at a frequency $$ \omega $$ ω and the other at a frequency near a multiple of the first one, $$ n \omega $$ n ω where $$ n $$ n is an integer greater than 1, is investigated. It is observed that such systems tend to exhibit a consistent pattern of master–slave relationship. This phenomenon is geometrically elucidated by considering the interaction dynamics: while the multiple bursts of the faster oscillator tend to cancel each other out upon impacting the slower oscillator, the single burst of the slower oscillator on the faster has a secular effect. We propose that this synchronization pattern, arising from perturbative impacts, is prevalent across various physical systems. Further experimental validation of these findings could contribute to a deeper understanding of synchronization phenomena and their implications in natural and technological domains.

Sedimentary facies controlled biogeochemical process of biotic extinction and turnover across the Cambrian SPICE event

The Steptoean positive carbon isotope excursion (SPICE) event, one of the largest carbon cycle perturbations in the Cambrian, coincides with shallow-shelf-fauna extinction and plankton revolution (critical transition of plankton). The event is globally documented, but biogeochemical responses of these biotic evolutions in varying facies environments are not well understood. Here high-resolution paired δ18Ocarb, δ13Ccarb and δ13Corg datasets from varied paleodepth environments in the Tarim Basin, NW China reveal facies-dependent signatures of the event, with globally synchronous patterns but notable intra-basinal variability. Shallow marine facies record the end-Marjuman extinction with a distinct negative δ13Corg excursion prior to the event, while the transitional facies region marks twice positive δ13C excursions corresponding to an asynchronous plankton revolution from shallow and deep areas during the event. The varying isotope responses are interpreted in the context of primary productivity and redox conditions, with deeper basins recording more 13C enriched signals (i.e., higher δ13C) due to greater organic matter preservation under anoxic conditions, compared to the platform area. The biotic extinction, the planktonic revolution and the interaction of organisms along the shallow to deep marine depth gradient were reflected by the significant isotopic shifts recorded during the event, suggesting depth-dependent biogeochemical processes that shaped marine ecosystems.

Symmetry breaker governs synchrony patterns in neuronal inspired networks.

Experiments in the human brain reveal switching between different activity patterns and functional network organization over time. Recently, multilayer modeling has been employed across multiple neurobiological levels (from spiking networks to brain regions) to unveil novel insights into the emergence and time evolution of synchrony patterns. We consider two layers with the top layer directly coupled to the bottom layer. When isolated, the bottom layer would remain in a specific stable pattern. However, in the presence of the top layer, the network exhibits spatiotemporal switching. The top layer in combination with the inter-layer coupling acts as a symmetry breaker, governing the bottom layer and restricting the number of allowed symmetry-induced patterns. This structure allows us to demonstrate the existence and stability of pattern states on the bottom layer, but most remarkably, it enables a simple mechanism for switching between patterns based on the unique symmetry-breaking role of the governing layer. We demonstrate that the symmetry breaker prevents complete synchronization in the bottom layer, a situation that would not be desirable in a normal functioning brain. We illustrate our findings using two layers of Hindmarsh-Rose (HR) oscillators, employing the Master Stability function approach in small networks to investigate the switching between patterns.

Characteristics of phase synchronization in electrohysterography and tocodynamometry for preterm birth prediction

Preterm birth prediction is important in prenatal care; however, it remains a significant challenge due to the complex physiological mechanisms involved. This study aimed to explore the feasibility of phase synchronization of multiple oscillatory components across electrohysterography (EHG) and tocodynamometry (TOCO) signals to identify preterm births using advanced machine-learning techniques. Using an open-access EHG dataset, we first assessed the degree of phase synchronization of five specified frequency ranges from 0.08 to 5.0 Hz in three individual EHG signals by constructing two distinct sets of mean phase coherence: the inclusion or exclusion of TOCO signals. We then employed two machine-learning models, XGBoost and TabNet, to classify preterm and term delivery conditions and analyze the predictive potential of these features. The models’ performance was evaluated by considering varying lengths of time windows and the use of overlapping windows. Our results demonstrate the importance of lower-frequency EHG signals and synchronization patterns across the horizontal plane of the abdomen, particularly synchronization between the upper and lower regions of the uterus. Furthermore, we observed a distinctive pattern in the high-frequency band (1.0–2.2 Hz), emphasizing the important role of the lower horizontal regions with other sites in the synchronization process. Interestingly, our findings indicated that TOCO signals, while not substantially enhancing the overall prediction performance, contributed to slightly improved accuracy rates when combined with EHG signals. This study suggests the critical role of EHG signals and their intricate spatiotemporal patterns in predicting preterm birth, providing insights for the development of more accurate and efficient prediction models.