Connectivity Pathways Research Articles

A biophysically constrained brain connectivity model based on stimulation-evoked potentials.

BackgroundSingle-pulse electrical stimulation (SPES) is an established technique used to map functional effective connectivity networks in treatment-refractory epilepsy patients undergoing intracranial-electroencephalography monitoring. While the connectivity path between stimulation and recording sites has been explored through the integration of structural connectivity, there are substantial gaps, such that new modeling approaches may advance our understanding of connectivity derived from SPES studies. New methodUsing intracranial electrophysiology data recorded from a single patient undergoing stereo-electroencephalography (sEEG) evaluation, we employ an automated detection method to identify early response components, C1, from pulse-evoked potentials (PEPs) induced by SPES. C1 components were utilized for a novel topology optimization method, modeling 3D electrical conductivity to infer neural pathways from stimulation sites. Additionally, PEP features were compared with tractography metrics, and model results were analyzed with respect to anatomical features. ResultsThe proposed optimization model resolved conductivity paths with low error. Specific electrode contacts displaying high error correlated with anatomical complexities. The C1 component strongly correlated with additional PEP features and displayed stable, weak correlations with tractography measures. Comparison with existing methodExisting methods for estimating neural signal pathways are imaging-based and thus rely on anatomical inferences. ConclusionsThese results demonstrate that informing topology optimization methods with human intracranial SPES data is a feasible method for generating 3D conductivity maps linking electrical pathways with functional neural ensembles. PEP-estimated effective connectivity is correlated with but distinguished from structural connectivity. Modeled conductivity resolves connectivity pathways in the absence of anatomical priors.

An integrated connectivity risk ranking for phosphorus and nitrogen along agricultural open ditches to inform targeted and specific mitigation management

Introduction: On dairy farms with poorly drained soils and high rainfall, open ditches receive nutrients from different sources along different pathways which are delivered to surface water. Recently, open ditches were ranked in terms of their hydrologic connectivity risk for phosphorus (P) along the open ditch network. However, the connectivity risk for nitrogen (N) was not considered in that analysis, and there remains a knowledge gap. In addition, the P connectivity classification system assumes all source–pathway interactions within open ditches are active, but this may not be the case for N. The objective of the current study, conducted across seven dairy farms, was to create an integrated connectivity risk ranking for P and N simultaneously to better inform where and which potential mitigation management strategies could be considered.Methods: First, a conceptual figure of known N open ditch source–pathway connections, developed using both the literature and observations in the field, was used to identify water grab sampling locations on the farms. During fieldwork, all open ditch networks were digitally mapped, divided into ditch sections, and classified in terms of the existing P connectivity classification system.Results and Discussion: The results showed that not all source–pathway connections were present across ditch categories for all species of N. This information was used to develop an improved open ditch connectivity classification system. Farmyard-connected ditches were the riskiest for potential point source losses, and outlet ditches had the highest connectivity risk among the other ditch categories associated with diffuse sources. Tailored mitigation options for P and N speciation were identified for these locations to intercept nutrients before reaching receiving waters. In ditches associated with diffuse sources, nitrate was introduced by subsurface sources (i.e., in-field drains and groundwater interactions from springs, seepage, and upwelling) and ammonium was introduced through surface connectivity pathways (i.e., runoff from internal roadways). On similar dairy farms where open ditches are prevalent, the integrated classification system and mapping procedure presented herein will enable a targeted and nutrient-specific mitigation plan to be developed. The same methodology may be applied to develop a bespoke integrated connectivity risk ranking for P and N along agricultural open ditches in other areas.

Bone Formation and Maintenance in Oral Surgery: The Decisive Role of the Immune System-A Narrative Review of Mechanisms and Solutions.

Based on the evidence of a significant communication and connection pathway between the bone and immune systems, a new science has emerged: osteoimmunology. Indeed, the immune system has a considerable impact on bone health and diseases, as well as on bone formation during grafts and its stability over time. Chronic inflammation induces the excessive production of oxidants. An imbalance between the levels of oxidants and antioxidants is called oxidative stress. This physio-pathological state causes both molecular and cellular damage, which leads to DNA alterations, genetic mutations and cell apoptosis, and thus, impaired immunity followed by delayed or compromised wound healing. Oxidative stress levels experienced by the body affect bone regeneration and maintenance around teeth and dental implants. As the immune system and bone remodeling are interconnected, bone loss is a consequence of immune dysregulation. Therefore, oral tissue deficiencies such as periodontitis and peri-implantitis should be regarded as immune diseases. Bone management strategies should include both biological and surgical solutions. These protocols tend to improve immunity through antioxidant production to enhance bone formation and prevent bone loss. This narrative review aims to highlight the relationship between inflammation, oxidation, immunity and bone health in the oral cavity. It intends to help clinicians to detect high-risk situations in oral surgery and to propose biological and clinical solutions that will enhance patients' immune responses and surgical treatment outcomes.

Exploring Comorbidity Between Anxiety and Depression in Spanish-Speaking School-Aged Children: A Network Analysis Approach.

Anxiety and depression are highly prevalent and comorbid problems in childhood, which deserve greater understanding for effective prevention and treatment. The main aim of the present study was to explore the comorbidity between anxiety and depression symptoms using a novel and valuable approach to study comorbidity, such as network analysis. Specifically, the connectivity between symptoms and possible relevant symptoms was examined through comorbidity estimation and shortest pathway networks, as well as bridge symptoms. This study comprised 281 Spanish-speaking children aged 8-12 years (45.2% girls), whose anxiety and depression symptoms were assessed through specific brief parent-report measures. Analyses revealed that in the comorbidity network, the most central symptoms were related to depression ("No good anymore," "Could never be as good," "Hated self," "Did everything wrong," "Nobody loved him/her") or anxiety ("Suddenly feels really scared"). Furthermore, it was found that the most central bridge symptoms, whose activation would play a key role in the activation of other domain symptoms, were anxiety symptoms such as "Trouble going to school" and "Suddenly feels really scared" and depression symptoms, such as "Could never be as good" and "Hated self." Additionally, the shortest path network suggested the existence of different possible pathways of connection between anxiety and depression symptoms. Overall, these findings help to understand the complexity of the anxiety-depression comorbidity. It suggests the existence of central and bridge symptoms that complement previous studies, which may be potential targets for interventions to prevent and treat childhood anxiety and depression.

Morphine- and foot shock-responsive neuronal ensembles in the VTA possess different connectivity and biased GPCR signaling pathway.

Background: Neurons in the ventral tegmental area (VTA) are sensitive to stress and their maladaptation have been implicated in the psychiatric disorders such as anxiety and addiction, etc. The cellular properties of the VTA neurons in response to different stressors related to different emotional processing remain to be investigated. Methods: By combining immediate early gene (IEG)-dependent labeling, rabies virus tracing, ensemble-specific transcriptomic analysis and fiber photometry recording in the VTA of male mice, the spatial distribution, brain-wide connectivity and cellular signaling pathways in the VTA neuronal ensembles in response to morphine (Mor-Ens) or foot shock (Shock-Ens) stimuli were investigated. Results: Optogenetic activation of the Mor-Ens drove approach behavior, whereas chemogenetic activation of the Shock-Ens increased the anxiety level in mice. Mor-Ens were clustered and enriched in the ventral VTA, contained a higher proportion of dopaminergic neurons, received more inputs from the dorsal medial striatum and the medial hypothalamic zone, and exhibited greater axonal arborization in the zona incerta and ventral pallidum. Whereas Shock-Ens were more dispersed, contained a higher proportion of GABAergic neurons, and received more inputs from the ventral pallidum and the lateral hypothalamic area. The downstream targets of the G protein and β-arrestin pathways, PLCβ3 and phosphorylated AKT1Thr308, were relatively enriched in the Mor-Ens and Shock-Ens, respectively. Cariprazine, the G-protein-biased agonist for the dopamine D2 receptor, increased the response of Mor-Ens to sucrose water and decreased the anxiety-like behavior during morphine withdrawal, whereas the β-arrestin-biased agonist UNC9994 decreased the response of Shock-Ens to tail suspension. Conclusions: Taken together, these findings reveal the heterogeneous connectivity and signaling pathways of the VTA neurons in response to morphine and foot shock, providing new insights for development of specific interventions for psychiatric disorders caused by various stressors associated with different VTA neuronal functions.

Bifidobacterium pseudonumeratum W112 alleviated depressive and liver injury symptoms induced by chronic unpredictable mild stress via gut-liver-brain axis.

Several studies indicated that depression is associated with liver injury. The role of probiotics in alleviating depression is focused on improving the abnormalities of the central nervous system through the gut-brain axis, while the effect on liver injury is still unclear. The aim of this study was to elucidate the potential link between the antidepressant effect of a potential probiotic strain Bifidobacterium pseudocatenulatum W112 and its effect on alleviating liver injury. The 4-week-old Kunming mice were exposed to chronic stress for 4 weeks to establish a depression model. The depression-like behavior and related biomakers in chronic unpredictable mild stress (CUMS) mice were altered by supplemented with W112 for 2 weeks. Meanwhile, the modulation effect of W112 the gut microbiota in CUMS mice also result in an increase in the abundance of beneficial bacteria and a decrease in the abundance of harmful bacteria. Significantly, liver injury was observed in CUMS model mice. W112 improved liver injury by reducing AST/ALT in serum. Quantitative PCR results indicated that the mechanism of action of W112 in ameliorating liver injury was that the altered gut microbiota affected hepatic phospholipid metabolism and bile acid metabolism. In short, W112 could significantly improve the depressive and liver injury symptoms caused by CUMS. The gut-liver-brain axis is a potential connecting pathway between the antidepressant effects of W112 and its alleviation of liver injury.

Study of Brain Neuroplasticity Analysis in Response to the Learning Process

Neuroplasticity, encompassing synaptic, structural, and functional plasticity, forms the biological basis of the brain's ability to retain information, improve cognitive function, and memory. Synaptic plasticity, which involves changing the connections between neurons at synapses, creates the foundation for memory formation and maintenance. Through phenomena such as Long-Term Potentiation (LTP) and Long-Term Depression (LTD), synaptis-synapses can increase or decrease strength, allowing the formation of long-lasting memory traces. Structural plasticity, which involves changes in the physical structure of neurons and brain tissue, including the formation of new dendrites, synaptic branches, and even neurogenesis. This demonstrates the brain's capacity to actively renovate itself, form new connection pathways, and improve responses to the environment and learning. Functional plasticity indicates the brain's flexibility in changing the functions and tasks of specific brain areas in response to activity or learning.

The online world as a means of connection and disconnection during the COVID-19 pandemic: A test of the interpersonal-connections-behaviour framework

BackgroundThe interpersonal-connections-behaviour framework proposes that social media is helpful/unhelpful to the individual to the extent that it facilitates/hinders satisfaction of core needs for acceptance and belonging (connecting and disconnecting pathways). However, little research has, to date, explicitly tested this framework. MethodsBoth pathways were explored in a cross-sectional sample of UK adults at the start of the pandemic (N = 632) and in longitudinal (cross-lagged) analyses (N = 227–240). Participants completed measures of online and offline socialising with friends and family (connecting pathway), and online and offline social comparisons (disconnecting pathway), anxiety, depression and loneliness. ResultsIn cross-sectional analyses higher levels of online comparisons were associated with poorer mental health, an effect that survived after controlling for offline comparisons, and was partially mediated by loneliness. Counter to our predictions, online socialising was also associated with poorer mental health. Longitudinal analyses did not support predicted directions of causality. LimitationsLimitations include a lack of testing of individual-level moderators, the use of single item questions to probe some constructs, and an inability to test for effects potentially operating at different time-scales. ConclusionsThe findings reported partially support the interpersonal-connections-behaviour framework in highlighting a disconnecting (but not connecting) pathway between online engagement and mental health. From a clinical perspective they highlight the importance of including people's online lives when considering mental health risk and resilience, particularly (one might argue) during periods of social isolation.

Identifying community assembling zones and connectivity pathways in the Tropical Southwestern Atlantic Ocean

Dispersal is more intense in the ocean than on land because most marine taxa present planktonic life stages that are transported by currents even without specific morphological traits. Thus, species dispersal shapes the distribution of biodiversity along seascapes and drives the composition of biodiversity assemblages. To identify marine assembling zones which characterise spatial areas particularly prone to receive and retain similar animal assemblages from the regional pool of species through passive dispersal, we propose a community‐based approach grounded on Lagrangian simulations of plankton dispersal. This novel approach was applied to communities (coast, outer shelf, slope, seamounts and islands; 0–80 m depth) of the Tropical Southwestern Atlantic and used to assess connectivity pathways. For that, we classified the modelled particles in 15 categories according to biological traits (planktonic life duration and spawning habitat) of representative planktonic communities. From the hierarchical clustering of the multivariate matrix containing the amount of arriving particles from each category in each cell we defined 14 assembling zones. Results highlighted that the assembling zones were mostly shaped by the degree of exposure to currents and the presence of mesoscale features (eddies, recirculation) derived from the interaction between these currents and coastlines. The boundaries, dispersal and connectivity patterns of these zones consistently align with local and regional in situ spatial distribution and abundance patterns of organisms, and provide an appropriate basis for the formulation of ecological hypotheses in the metacommunity framework to be tested in situ, such as the balance between species sorting and mass effect assembling archetypes. This approach, when coupled with the knowledge of other processes shaping communities' structure and distribution, provides important insights for regions and animal groups for which knowledge is limited or absent, and more generally allows for a comprehensive overview of the distribution of distinct communities and connectivity pathways along marine environments.

Building professional resilience: School music teachers’ instructional practice development under curriculum reform

This study used a mixed-methods approach to investigate the characteristics and development of teachers’ resilience profiles during ongoing school music curriculum reforms in mainland China. During a 12-month voluntary teacher development project, seven mid-career schoolteachers based in Shenzhen City, South China, helped collect longitudinal data on their resilience profiles and instructional practices. Inspired by Mansfield’s resilience model, this study developed a model of the essential dynamics in the resilience development process of individual teachers. The working model mapped the identified factors of teachers’ resilience development into a coordinate system that incorporated two approaches (receptive and autonomous) to resilience building, with two scenarios (mandatory or conditional) in curriculum implementation. The findings suggested that (a) teachers exhibited different resilience properties shaped by both personal and contextual factors, as well as the connection pathways between factors, and (b) teachers used a variety of strategies to build resilience to policy and environmental constraints, including mentoring, peer support, problem-solving, relationship management, and pedagogy innovation. These strategies were mapped onto a functional model for resilience development in curriculum implementation, which further extended the application of Mansfield’s conceptual framework to teacher education programs. Although this study recognized the value of quantitative research instruments in capturing resilience profiles, the ecological validity and reliability concerns of these measurements were also discussed.

Neural basis underlying the relation between internet addiction tendency and sleep quality: The intrinsic default-mode network connectivity pathways

Internet addiction (IA) tendency is considered an addictive behavior that results from excessive Internet use, and severely affecting an individual's physical health, emotion, and sleep. Although previous studies indicated that IA tendency was negatively correlated with sleep quality, the underlying neural basis of this relationship remained unclear. To address this issue, we utilized resting-state functional connectivity (RSFC) analysis to identify the neural pathways of the relationship between IA tendency and sleep quality. The behavioral results indicated a positive correlation between these two factors. And RSFC results revealed that IA tendency was positively related to the strength of functional connectivity within the default-mode network (DMN), including the right precuneus-left middle temporal gyrus (rPrcu-lMTG), the left anterior cingulate-left superior frontal gyrus (lAC-lSFG), and the left inferior parietal lobe-left medial superior frontal gyrus (lIPL-lMSFG). More importantly, mediation analysis demonstrated that IA tendency could mediate the relationship between these functional couplings and sleep quality. In conclusion, our findings suggest that intrinsic DMN connectivity may be an important neural pathways underlying the effects of IA tendency on sleep quality, and provide neural evidence for understanding the relationship between IA tendency and sleep quality.

The indirect effects of socioeconomic position on lung function: a mediation analysis

Abstract Background There is a strong link between socioeconomic position and pulmonary health, but less is known about their connecting pathways. We analyzed the direct and indirect effects of education and deprivation on lung function using air pollutants in a mediation framework. Methods We used spirometry tests, demographic, and health information on 5703 Czechs, with a mean age of 58.3 ± 7.1 years from the Health, Alcohol, and Psychosocial Factors in Eastern Europe (HAPIEE) cohort study between 2002 to 2005. The annual means of particulate matter 10 (PM10), particulate matter 2.5 (PM2.5), and nitrogen dioxide (NO2) estimated by Shen et al. (2022) for the years 2000 to 2003 were matched to the geographic addresses of the participants. Multiple mediation analyses assessed the relationship between socioeconomic variables (education and deprivation) and the predicted percentage of Forced Expiratory Volume in the first second (FEV1) and the role of mediators: PM10 or PM2.5 or NO2, smoking behavior, and body mass index (BMI). The models were adjusted for sex, age. Results 9.27% of individuals had <70% of the predicted percentage of FEV1. We tested the first model using PM10, smoking, and BMI as mediators. We found significant indirect effects from education through PM10 (β = 0.17, CI95%: 0.10-0.25), BMI (β = 0.36, 0.25-0.47), and smoking (β = 0.17, 0.08-0.25) with indirect effects explaining 34% of the total effect of education. The indirect effect of deprivation was significant only through smoking (β=-0.11, -0.14 to -0.07), explaining 31% of the effect of deprivation. Similar results were observed when we tested a second model using PM2.5 instead of PM10, and a third model including NO2 instead of PM10. Conclusions Air pollutants seem to mediate the association between education and lung function, but not between deprivation and lung function, however, further research is needed to confirm our findings. Key messages • Higher education appears to be associated with better environmental factors that prevent loss of lung function. • Most of the routes that connect socioeconomic factors and lung function remain unclear.

Artificial Neural Network for Classification of Dengue Fever Using Backpropagation Algorithm

Fever is an increase in body temperature to higher than usual. Normal human body temperature is at 37oC, if the body temperature is more than this figure, it indicates a fever caused by infectious or non-infectious factors. The main symptom of Dengue hemorrhagic fever is high fever with a temperature between 30oC - 40oC which appears suddenly, the fever lasts for 7 days and occurs continuously, body temperature can be normal or low, then will rise slowly every day and can reach 40oC . These two diseases are still a public health problem in urban areas, including in the cities of Binjai and Medan. The problem that has occurred so far is that people in general cannot differentiate the symptoms of Dengue Fever from Malaria, so the treatment given only provides ordinary fever medicine, so that within three days there is no change and the high body temperature makes the patient know that someone has dengue fever. Therefore, the solution provided in this research is to find out the physical characteristics experienced by the sufferer before further diagnosis is carried out. If someone has a fever above 38oC, the body has red spots, irregular breathing, immediately go to the doctor because these symptoms indicate symptoms of dengue hemorrhagic fever or malaria fever. Artificial neural networks are an information processing system designed to imitate the workings of the human brain by carrying out a learning process through changing the weights of synapses. The human brain consists of millions of interconnected neurons known as biological neurons. Each neuron consists of a cell that has a number of dendrites (input) and an axon (output). Axons connect to other neurons through connecting pathways that produce chemical reactions when responding to incoming input. The input required includes the number of input variables, input variable values, weights, learning rate, threshold, maximum epoh and target (output) with the error value classification used is Mean Absolute Error (MAE), there are 2 types of disease with fever symptoms used. The types of disease are dengue hemorrhagic fever and malaria and the system will be designed using the Visual Basic 2010 programming language. From the results of the research that has been carried out, classification results are obtained with a value of 0.893619481 or rounded to equal 1 and classified as dengue hemorrhagic fever.

Microstructural Model of Indacenodithiophene-co-benzothiadiazole Polymer: π-Crossing Interactions and Their Potential Impact on Charge Transport.

Morphological and electronic properties of indacenodithiophene-co-benzothiadiazole (IDTBT) copolymer with varying molecular weights are calculated through combined molecular dynamics (MD) and quantum chemical (QC) methods. Our study focuses on the polymer chain arrangements, interchain connectivity pathways, and interplay between morphological and electronic structure properties of IDTBT. Our models, which are verified against GIWAXS measurements, show a considerable number of BT-BT π-π interactions with a (preferential) perpendicular local orientation of polymer chains due to the steric hindrance of bulky side chains around IDT. Although our models predict a noncrystalline structure for IDTBT, the BT-BT (interchain) crossing points show a considerable degree of short-range order in spatial arrangement which most likely result in a mesh-like structure for the polymer and provide efficient pathways for interchain charge transport.

Increased Cerebello-Prefrontal Connectivity Predicts Poor Executive Function in Congenital Heart Disease.

Children and adolescents with congenital heart disease (CHD) are at risk for cognitive impairments, such as executive function deficits and motor delays, which can impact their academic and adaptive functioning as well as their quality of life. We investigated whether alterations in connectivity between the prefrontal and cerebellar brain structures exist between CHD and control cohorts and if these alterations could predict cognitive or motor impairment among youths with CHD. 53 participants with CHD and 73 healthy control participants completed multi-modal magnetic resonance imaging (MRI) of the brain, including high-resolution diffusion tensor imaging at 3T. We measured connectivity from masked regions of interest in the cerebellum to the frontal cortex using a probabilistic tractography method. Participants also completed neuropsychological tests of cognitive and motor skills using the NIH Toolbox. In the CHD group, fractional anisotropy (FA) was increased in the cognitive loop connectivity pathways, including from the right cerebellum to the left thalamus (p = 0.0002) and from the left thalamus to the left medial frontal gyrus (MFG) (p = 0.0048) compared with the healthy control group. In contrast, there were no differences between CHD and controls in motor loop connectivity pathways. An increase in FA from the right thalamus to the MFG tract in the cognitive loop (posterior subdivision) predicted (p = 0.03) lower scores on the NIHTB tests, including those of executive functioning. A transient increase in connectivity of the cognitive loop in the adolescent group was observed relative to the child and adult groups. Our results suggest that selective alteration of cerebellum-cerebral connectivity circuitry within the cognitive loops predicts cognitive dysfunction in CHD youth. Our study suggests a critical period of cerebellar circuitry plasticity in the adolescent period in CHD subjects that drives neurocognitive function. Further replication and validation in other pediatric CHD cohorts is warranted for future work.

Better Covalent Connection in a Molecular Triad Enables More Efficient Photochemical Energy Storage.

Numerous studies have explored the kinetics of light-induced charge separation and thermal charge recombination in donor-acceptor compounds, but quantum efficiencies have rarely been investigated. Here, we report on two essentially isomeric molecular triads, both comprising a π-extended tetrathiafulvalene (ExTTF) donor, a ruthenium(II)-based photosensitizer, and a naphthalene diimide (NDI) acceptor. The key difference between the two triads is how the NDI acceptor is connected. Linkage at the NDI core provides stronger electronic coupling to the other molecular components than connection via the nitrogen atoms of NDI. This change in molecular connectivity is expected to accelerate both energy-storing charge separation and energy-wasting charge recombination processes, but it is not a priori clear how this will affect the triad's ability to store photochemical energy; any gain resulting from faster charge separation could potentially be (over)compensated by losses through accelerated charge recombination. The new key insight emerging from our study is that the quantum yield for the formation of a long-lived charge-separated state increases by a factor of 5 when going from nitrogen- to core-connected NDI, providing the important proof of concept that better molecular connectivity indeed enables more efficient photochemical energy storage. The physical origin of this behavior seems to root in different orbital connectivity pathways for charge separation and charge recombination, as well as in differences in the relevant orbital interactions depending on NDI connection. Our work provides guidelines for how to discriminate between energy-storing and energy-wasting electron transfer reactions in order to improve the quantum yields for photochemical energy storage and solar energy conversion.

Unfolding the direct connectivity of the occipital cortex with the hypothalamic, septal and BNST nuclei of the human brain

The hypothalamus plays essential roles in the human brain by regulating feeding, fear, aggression, reproductive behaviors, and autonomic activities. The septal nuclei and the bed nucleus of stria terminalis (BNST) are also known to be involved in control of autonomic, motivational, learning, emotional and associative processes in the human brain. Multiple animal dissection studies have revealed direct connectivity between central limbic gray matter nuclei and occipital cortex, particularly from the hypothalamic, septal and BNST nuclei. However, the detailed anatomy of this connectivity in the human brain has yet to be determined. The primary objective of this study was to explore the utility of high spatial and high angular resolution diffusion weighted tractography techniques for mapping the connectivity pathways between the occipital cortex and central limbic gray matter nuclei in the human brain. We studied 30 healthy adult human brains, delineated, and reconstructed the trajectory of the occipito-hypothalamic/septal/BNST for the first time in the human brain.

Predicted connectivity pathways between grizzly bear ecosystems in Western Montana

Habitat and corridor mapping are key components of many conservation programs. Grizzly bear populations in the continental US are fragmented and connectivity among federal recovery areas is a conservation goal. Building on recent work, we modeled movements to predict areas of connectivity, using integrated step selection functions (iSSFs) developed from GPS-collared grizzly bears (F = 46, M = 19) in the Northern Continental Divide Ecosystem (NCDE). We applied iSSFs in a >300,000 km2 area including the NCDE, Cabinet–Yaak (CYE), Bitterroot (BE), and Greater Yellowstone (GYE) Ecosystems. First, we simulated directed movements (randomized shortest paths with 3 levels of exploration) between start and end nodes across populations. Second, we simulated undirected movements from start nodes in the NCDE, CYE, or GYE (no predetermined end nodes). We summarized and binned results as classes 1 (lowest relative predicted use) – 10 (highest relative predicted use) and evaluated predictions using 127 outlier grizzly bear locations. Connectivity pathways were primarily associated with mountainous areas and secondarily with river and stream courses in open valleys. Values at outlier locations indicated good model fit and mean classes at outlier locations (≥7.4) and Spearman rank correlations (≥0.87) were highest for undirected simulations and directed simulations with the highest level of exploration. Our resulting predictive maps can facilitate on-the-ground application of this research for prioritizing habitat conservation, human-bear conflict mitigation, and transportation planning. Additionally, our overall modeling approach has utility for myriad species and conservation applications.

Global Consequences of Regional Connectivity Along the Antarctic Margin

AbstractObservations and modeling studies indicate that ocean and cryosphere dynamics at the Antarctic margin are rapidly evolving and will continue to do so in the face of unabated climate warming. Despite occupying a minute fraction of the world ocean's volume, local dynamics in this region may play an outsized role in the evolving global climate system. Water masses transported along and across the continental shelf influence Antarctic Ice Sheet (AIS) stability, Dense Shelf Water (DSW) production, oceanic heat and carbon uptake, nutrient distributions, and ecosystems. Changes in these processes may feedback onto the global climate system with significant remote consequences, including accelerated global sea level rise. Recently, Dawson et al. (2023, https://doi.org/10.1029/2022JC018962) combined results from a high‐resolution ocean‐sea ice model with offline Lagrangian particle tracking to constrain pathways and timescales of connectivity along the Antarctic margin. Their findings revealed widespread circumpolar connectivity, with waters able to circumnavigate Antarctica within two decades and reach neighboring shelf regions within 1–5 years. The results provide important context of timescales that anomalies from AIS mass loss or Circumpolar Deep Water intrusions may propagate downstream and feedback onto AIS stability or DSW formation. The authors highlight the importance of along‐slope and along‐shelf currents in setting connectivity timescales and pathways. Combined with other recent studies suggesting significant changes in Antarctic regional ocean circulation in response to warming, the findings of Dawson et al. (2023, https://doi.org/10.1029/2022JC018962) suggest the Antarctic margin is likely to significantly evolve over the 21st century in ways we are just starting to unravel.

Enhancement of Isotropic Heat Dissipation of Polymer Composites by Using Ternary Filler Systems Consisting of Boron Nitride Nanotubes, h-BN, and Al2O3.

In this research article, a poly(dimethylsiloxane) (PDMS)-based composite was postulated adapting an interactive ternary filler system consisting of Al2O3, hexagonal boron nitride (h-BN), and boron nitride nanotubes (BNNT) to construct a continuous three-dimensional (3D) structure for thermal attenuation. Al2O3 was imposed as a main filler, while h-BN and BNNT were assimilated to form interconnected heat conduction pathways for effective thermal dissipation. The structured framework articulates a profound improvement in isotropic thermal conductivity considering both axial and radial heat dissipation. The presence of h-BN entails uniform heat distribution in a planar mode, eliminating the occurrence of hotspots, while BNNT constructed a connecting phonon pathway in various directions, which insinuates effective overall thermal transport. The generated ternary filler composites attained an isotropic ratio of 1.35 and a thermal conductivity of 7.50 W/mK, which is a 36-fold (∼3650%) increase compared to neat PDMS resin and almost 3-fold (∼297%) that of the Al2O3 unary filler composite and ∼53% that of its binary counterpart, partaking interfacial thermal gaps of ∼36.15 and ∼62.24% on practical heating performance relative to its counterparts. Moreover, the incorporation of BNNT on a traditional spherical and planar filler offers an advantage not only in thermal conductivity but also in thermal and structural stability. Improvement in thermal stability is stipulated due to a melting point (Tm) shift of ∼11 °C upon the assimilation of BNNT. Mechanical permeance reinforcement was also observed with the presence of BNNT, showcasing a 31.5% increase in tensile strength and a 53% increase in Young's modulus relative to the singular filler composite. This exploration administers a new insight into heat dissipation phenomena in polymeric composites and proposes a simple approach to their design and assembly.