Search

Hydrological drought and river disconnectivity worsen from dams and human activities. This research investigates how dam constructions exacerbate hydrological drought and river disconnectivity in Apalachicola River system. Data from two hydrological stations (1928-2022), a hydrographic survey, high-resolution LiDAR, and a triangular irregular network (TIN) were used to identify three connectivity flow (141.5 m3/s, 169.8 m3/s, and 226.4 m3/s) categories, each impacting floodplain differently. A relative elevation model (REM) was also developed for floodplain connectivity assessment. Findings show a significant increase in the frequency, duration, and magnitude of connectivity low flow events from pre-dam to post-dam periods, especially at the 169.8 m³/s connectivity flow threshold. A 20th percentile variable threshold shows increasing hydrological drought. Drought increases have led to decreased connectivity between tributaries and the main river system, and an increase in the moderately disconnected floodplain area from 37.1% to 46.0%. Adaptive management strategies are needed to address drought-induced floodplain disconnectivity [ABSTRACT FROM AUTHOR]

This theoretical and empirical investigation builds upon the concept of 'slantwise behavior' to further complicate notions of the 'digital disengagement' of subjects within technological infrastructures such as Facebook. It has been previously suggested that the ubiquity of the data privacy paradox is the most common reason for disengagement practices. Our study contributes to this discussion by examining subjects' disengagement on Social Network Sites (SNS). While numerous concepts concerning disconnection and disengagement from SNS have been conceptualized by media theorists, largely based on a binary construct of resistance or domination, our work proposes an alternative conceptualization of subjects' disengagement. By employing a qualitative methodological approach and using 30 semi-structured interviews to capture subjects' discursive patterns, we illustrate that disengagement on Facebook can be seen as a hybrid reaction and a complex phenomenon in which certain disconnection practices cannot be easily classified as resistance practices or as indications of the internalization of domination but rather are best understood as slantwise behaviors, that is, actions that may unintentionally lead to obfuscation. [ABSTRACT FROM AUTHOR]

The Bir el-Umdan cistern, a prominent archaeological site in the Judean Desert, is one of the largest and best preserved water systems in the region. Hewn in chalk, the cistern area measures 114 m2 and has a ~700 m3 volume. Two massive columns, each with a base diameter of 2.5 m, support the ceiling within the cistern's interior. This impressive structure is estimated to date back to the Hellenistic to Late Antiquity periods based on its architectural characteristics. Historical records indicate that the cistern was documented on 19th-century maps but disappeared from the 1935 and 1943 British Mandate maps. Its reappearance on the 1967 Survey of Israel map includes an upstream road disconnecting the cistern from its natural drainage basin. Despite its renovation in the 2010s, the cistern's water supply remains limited due to its reduced catchment area, which now constitutes only 25% of its original size. Runoff coefficients calculated for the cistern's drainage basin are relatively low (1.4% to 8.1%) compared to other desert regions. We analyzed the 21st-century runoff coefficient and recurrence interval over the original drainage basin (0.12 km2) to estimate the water volumes in antiquity. Our analysis suggests that using an 8.1% runoff coefficient, the estimated water volume is 806 m3, implying a cistern overflow every 6–7 years. A more conservative estimate using a 5% runoff coefficient yields a water volume of 500 m3 and a 15-year recurrence interval. Sediment analysis reveals that silt particles dominate the sediment accumulated in the cistern and its upstream sedimentation basins. The consistent grain size distribution throughout the system indicates rapid water flow during flood events. Reconstructing the sedimentation history is challenging due to potential maintenance and possible dredging and cleaning operations. [ABSTRACT FROM AUTHOR]

The concept of structural reserve in stroke reorganization assumes that the relevance of the contralesional hemisphere strongly depends on the brain tissue spared by the lesion in the affected hemisphere. Recent studies, however, have indicated that the contralesional hemisphere's impact exhibits region-specific variability with concurrently existing maladaptive and supportive influences. This challenges traditional views, necessitating a nuanced investigation of contralesional motor areas and their interaction with ipsilesional networks.Our study focused on the functional role of contralesional key motor areas and lesion-induced connectome disruption early after stroke.Online TMS data of twenty-five stroke patients was analyzed to disentangle interindividual differences in the functional roles of contralesional primary motor cortex (M1), dorsal premotor cortex (dPMC), and anterior interparietal sulcus (aIPS) for motor function. Connectome-based lesion symptom mapping and corticospinal tract lesion quantification were used to investigate how TMS effects depend on ipsilesional structural network properties.At group and individual levels, TMS interference with contralesional M1 and aIPS but not dPMC led to improved performance early after stroke. At the connectome level, a more disturbing role of contralesional M1 was related to a more severe disruption of the structural integrity of ipsilesional M1 in the affected motor network. In contrast, a detrimental influence of contralesional aIPS was linked to less disruption of the ipsilesional M1 connectivity.Our findings indicate that contralesional areas distinctively interfere with motor performance early after stroke depending on ipsilesional structural integrity, extending the concept of structural reserve to regional specificity in recovery of function.

KReg is the category of compact regular frames and frame homomorphisms. A class of KReg frames H is a hull class provided that: (i) H is closed under isomorphic copies; (ii) for every F ∈ KReg there exist an h F ∈ H and a morphism h F such that F ≤ h F h F is essential; (iii) if F ≤ ϕ H is essential and H ∈ H , then there exists h ϕ : h F ⟶ H for which ϕ = h ϕ · h F . This work provides techniques for identifying and generating hull classes in KReg . Moreover, for a compact regular frame F, we introduce and investigate various properties of projectability and disconnectivity of F and prove that for each property, P, the class of KReg -objects that satisfy P is a hull class in KReg . In addition, we provide examples of KReg hull classes that are not characterized by some form of projectability/disconnectivity and examples of classes of KReg -objects that are not hull classes. [ABSTRACT FROM AUTHOR]

The Bir el-Umdan cistern, a prominent archaeological site in the Judean Desert, is one of the largest and best preserved water systems in the region. Hewn in chalk, the cistern area measures 114 m2 and has a ~700 m3 volume. Two massive columns, each with a base diameter of 2.5 m, support the ceiling within the cistern’s interior. This impressive structure is estimated to date back to the Hellenistic to Late Antiquity periods based on its architectural characteristics. Historical records indicate that the cistern was documented on 19th-century maps but disappeared from the 1935 and 1943 British Mandate maps. Its reappearance on the 1967 Survey of Israel map includes an upstream road disconnecting the cistern from its natural drainage basin. Despite its renovation in the 2010s, the cistern’s water supply remains limited due to its reduced catchment area, which now constitutes only 25% of its original size. Runoff coefficients calculated for the cistern’s drainage basin are relatively low (1.4% to 8.1%) compared to other desert regions. We analyzed the 21st-century runoff coefficient and recurrence interval over the original drainage basin (0.12 km2) to estimate the water volumes in antiquity. Our analysis suggests that using an 8.1% runoff coefficient, the estimated water volume is 806 m3, implying a cistern overflow every 6–7 years. A more conservative estimate using a 5% runoff coefficient yields a water volume of 500 m3 and a 15-year recurrence interval. Sediment analysis reveals that silt particles dominate the sediment accumulated in the cistern and its upstream sedimentation basins. The consistent grain size distribution throughout the system indicates rapid water flow during flood events. Reconstructing the sedimentation history is challenging due to potential maintenance and possible dredging and cleaning operations.

Technological disconnectivity has turned into a tourist attraction in its own right: digital detox tourism celebrates temporary disconnection as a means for experiencing an "authentic" world. With pervasive digital media and a strong impetus to being available 24/7, this tourism has to answer not only the question of what has to be done to become disconnected, but also it has to highlight the pleasures disconnection may afford. Drawing on two case studies—a discourse analysis of self-organized unplugged travel writing and an ethnography of the detox event Camp Grounded—we argue that digital detox tourism relies heavily on staging and performing a distinction between the analog and the digital. The article introduces the notion "analogization" to capture practices, media, and infrastructure which support the creation and the blurring of this distinction. Thus, we argue that analogization, in contrast to digitalization, emphasizes that there is no "analog" per se. [ABSTRACT FROM AUTHOR]

Purpose of Review: Over the last decade, evidence suggests that a combination of behavioral and neuroimaging findings can help illuminate changes in functional dysconnectivity in schizophrenia. We review the recent connectivity literature considering several vital models, considering connectivity findings, and relationships with clinical symptoms. We reviewed resting state fMRI studies from 2017 to 2023. We summarized the role of two sets of brain networks (cerebello-thalamo-cortical (CTCC) and the triple network set) across three hypothesized models of schizophrenia etiology (neurodevelopmental, vulnerability-stress, and neurotransmitter hypotheses). Recent Findings: The neurotransmitter and neurodevelopmental models best explained CTCC-subcortical dysfunction, which was consistently connected to symptom severity and motor symptoms. Triple network dysconnectivity was linked to deficits in executive functioning, and the salience network (SN)–default mode network dysconnectivity was tied to disordered thought and attentional deficits. Summary: This paper links behavioral symptoms of schizophrenia (symptom severity, motor, executive functioning, and attentional deficits) to various hypothesized mechanisms. [ABSTRACT FROM AUTHOR]

The development of new approaches indirectly measuring the structural disconnectome has recently led to an increase in studies investigating pairwise structural disconnections following brain damage. Previous studies jointly analyzed patients with left hemispheric and patients with right hemispheric lesions when investigating a behavior of interest. An alternative approach would be to perform analyses separated by hemisphere, which has been applied in only a minority of studies to date. The present simulation study investigated whether joint or separate analyses (or both equally) are appropriate to reveal the ground truth disconnections. In fact, both approaches resulted in very different patterns of disconnection. In contrast to analyses separated by hemisphere, joint analyses introduced a bias to the disadvantage of intra‐hemispheric disconnections. Intra‐hemispheric disconnections were statistically underpowered in the joint analysis and thus surpassed the significance threshold with more difficulty compared to inter‐hemispheric disconnections. This statistical imbalance was also shown by a greater number of significant inter‐hemispheric than significant intra‐hemispheric disconnections. This bias from joint analyses is based on mechanisms similar to those underlying the "partial injury problem." We therefore conclude that pairwise structural disconnections in patients with unilateral left hemispheric and with unilateral right hemispheric lesions exhibiting a specific behavior (or disorder) of interest should be studied separately by hemisphere rather than in a joint analysis. [ABSTRACT FROM AUTHOR]

While connectivity studies are becoming common in the Earth sciences, disconnectivity has received much less attention. Sediment storage is the direct result of sediment disconnectivity and can provide concrete evidence of the spatial patterns of disconnectivity at the catchment‐scale. In this study, we explore the catchment‐scale sediment dynamics of the Tahoma Creek watershed, a high‐gradient glacio‐volcanic landscape, within a sediment budget framework and identify and map sources of disconnectivity to determine whether they explain the spatial patterns and estimated efficiencies of sediment transfers. We found that up to 80% of the total eroded sediment is sourced from the proglacial zone. The proglacial zone is characterized by high connectivity resulting from frequent debris flows and floods, and rapidly responds to changing conditions. Down valley, however, sources of disconnectivity become increasingly more prevalent, the hillslopes become decoupled from the channel, and a majority of the eroded sediment is redeposited with as little as ∼15% reaching the outlet. The spatial distribution of sources of disconnectivity and their upslope affected areas explains, to a large degree, catchment‐scale sediment dynamics and sediment transfer efficiencies and is in close agreement with quantitative connectivity estimates. We find that steep, glaciated watersheds are predominantly disconnected over human timescales and suggest that disconnectivity is the dominant state of landscapes over most timescales of interest. Mapping sources of disconnectivity provides a straightforward and concrete approach to estimating system disconnectivity and can increase confidence when paired with quantitative indices. Plain Language Summary: Mountain watersheds supply freshwater and sediment to downstream river systems affecting flooding, fish habitat, and water quality. We argue that understanding the spatial and temporal patterns of sediment movement within a landscape requires knowing where and for how long sediment is stored and the overall efficiency of sediment transfer between different parts of the landscape. We illustrate the importance and utility of mapping landforms and landscape characteristics that delay or disrupt sediment movement using the Tahoma Creek watershed as an example. This watershed drains a portion of Mount Rainier, a volcano shaped by glaciers in Washington, USA, and is incredibly dynamic. We find that landforms and landscape characteristics that limit sediment movement are common and that mapping them gives an accurate picture of sediment movement patterns. Glaciers dramatically reshape the landscape, which controls sediment supply and movement patterns, and their legacy remains for thousands of years after they retreat. We also make use of high‐resolution elevation data representing the land surface in 2002, 2008, and 2012 to quantify how much erosion, transport, and deposition occurred and how efficiently sediment was transported. We find that sediment is transported more efficiently during extreme events, such as the 2006 floods. Key Points: Disconnectivity is the dominant but inefficient state of a system in transferring matter and energy within and between system componentsSources of disconnectivity were found to accurately explain catchment‐scale sediment dynamicsDuring extreme events, the efficiency of sediment transfer increases, resulting in rapid adjustment [ABSTRACT FROM AUTHOR]

• Contralesional TMS effects strongly depend on the ipsilesional structural integrity. • The impact of the ipsilesional structural reserve is regional specific. • Individual functional and structural data could optimize treatment strategies. The concept of structural reserve in stroke reorganization assumes that the relevance of the contralesional hemisphere strongly depends on the brain tissue spared by the lesion in the affected hemisphere. Recent studies, however, have indicated that the contralesional hemisphere's impact exhibits region-specific variability with concurrently existing maladaptive and supportive influences. This challenges traditional views, necessitating a nuanced investigation of contralesional motor areas and their interaction with ipsilesional networks. Our study focused on the functional role of contralesional key motor areas and lesion-induced connectome disruption early after stroke. Online TMS data of twenty-five stroke patients was analyzed to disentangle interindividual differences in the functional roles of contralesional primary motor cortex (M1), dorsal premotor cortex (dPMC), and anterior interparietal sulcus (aIPS) for motor function. Connectome-based lesion symptom mapping and corticospinal tract lesion quantification were used to investigate how TMS effects depend on ipsilesional structural network properties. At group and individual levels, TMS interference with contralesional M1 and aIPS but not dPMC led to improved performance early after stroke. At the connectome level, a more disturbing role of contralesional M1 was related to a more severe disruption of the structural integrity of ipsilesional M1 in the affected motor network. In contrast, a detrimental influence of contralesional aIPS was linked to less disruption of the ipsilesional M1 connectivity. Our findings indicate that contralesional areas distinctively interfere with motor performance early after stroke depending on ipsilesional structural integrity, extending the concept of structural reserve to regional specificity in recovery of function. [ABSTRACT FROM AUTHOR]

Extreme waterfall conditions cause partition of aquatic ecosystems of waterfall streams into discrete zones. To assess the features of aquatic ecosystems that function in waterfall streams, macroinvertebrate communities of the Tevenek River (Lake Teletskoye basin, Northeastern Altai) were examined above and below the waterfall. The diversity, abundance, and biomass of macroinvertebrates were higher above than below the barriers. Gammarus korbuensis showed the most significant decrease in number (from 3.1 to 2.3 thousand ind./m2) probably due to the intensive use of amphipods as food for fish living in Lake Teletskoye. An additional factor in favor of the high species richness of macroinvertebrates in the upper reaches is the geomorphology of the waterfall river valley that contributes to the formation of more diverse conditions above the waterfalls. Hydrobiological studies of waterfall streams can help to understand the restructuring of benthic communities divided as a result of the human impact.

Wireless sensor Networks (WSNs) have proliferated in the past few years. Their power consumption and network lifetime has attracted researchers over the past decade. In addition, studying these networks in three-dimensional environment where nodes are randomly distributed in a three dimensional (3D) area in caves, underwater or underground reveals many more challenging tasks to prolong the network lifetime. One of the issues that these networks encounter is the disconnectivity or holes in the network. These holes prevent active sensor nodes from delivering their data to the sink or central node. In this work, an enhanced semi-clustering and hole detection multi-hops routing protocol (SCHDRP) is proposed to tackle the issue of disconnectivity and holes detection in the network. SCHDRP aggregates the sensed data from the sensor nodes and routes them without depleting the edge sensors nodes "located beside holes" power in the network. SCHDRP has been simulated and its results show that it detects the holes' edge nodes with an accuracy of 86% utilizing the average number of neighbors in the network with a threshold value of 10%. Moreover, SCHDRP has enhanced the network lifetime 200% over ordinary multi-hop routing protocols. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the popular centrality-based approaches to find a set of critical nodes whose deletion causes the most disconnectivity in the network. Demonstrating the weak points of these approaches which only consider a ranking factor, we propose an Enhanced Critical Node Detection (ECND) method which can work with any kind of ranking score by considering the structure of a network. We have designed a set of experiments using 24 different artificial and real-world networks, varying in the number of vertices and number of edges. Using two different objective functions including the number of connected components and the weighted average size of the connected components, experimental results show outperformance of ECND in comparison to all 8 other methods. [ABSTRACT FROM AUTHOR]

Forest fires and post‐fire practices influence sediment connectivity (SC). In this study, we use the 'aggregated index of connectivity' (AIC) to assess SC in five Mediterranean catchments (198–1090 ha) affected by a wildfire in 2012 in south‐eastern Spain. Two temporal scenarios were considered, immediately after the fire and before post‐fire management, and 2 years after the fire including all practices (hillslope barriers, check‐dams, afforestation, salvage logging and skid trails). One LiDAR (light detection and ranging)‐derived digital elevation model (DEM, 2 m × 2 m resolution) was generated, per scenario. The five catchment outlets were established as the computation target (AICOUT), and structural and functional SC were calculated. Index outputs were normalized to make the results of the non‐nested catchments comparable (AICN‐OUT). The output analysis includes the SC distribution along the catchments and at local scale (929 sub‐catchments, 677 in the burned area), the hillslope and channel measures' effect on SC, and a sedimentological analysis using observed area‐specific sediment yield (SSY) at 10 new (built after post‐fire practices) concrete check‐dams located in the catchments (SSY = 1.94 Mg ha−1 yr−1; σ = 1.22). The catchments with more circular shapes and steeper slopes were those with higher AICN‐OUT. The structural SC maps – removing the rainfall erosivity influence – allowed evaluating the actual role played by the post‐fire practices that reduced SC (x¯= − 1.19%; σ = 0.41); while functional SC was linked to the actual change of SC (x¯= + 5.32%; σ = 0.62). Hillslope treatments resulted in significant changes on AICN‐OUT at sub‐catchment scale with certain disconnectivity. A good and positive correlation was found between the SSY and the changes of AICN‐OUT. However, the coarse DEM resolution explained the lack of effect of the rock check‐dams – located on the secondary channels – on AICN‐OUT. AICN‐OUT proved to be a useful tool for decision making in post‐fire restoration, but an optimal input data is still necessary to refine calculations. [ABSTRACT FROM AUTHOR]

Internet of connected vehicles (IoCV) is one of the popular subclasses of vehicle ad hoc networks and an up-rising form based on new Internet, 5G, cloud, and edge computing features. The vehicle nodes in such networks can exchange the information with other nodes with the help of infrastructure or without prior infrastructure. For efficient data communication among the vehicle nodes, the routing protocols play a significant role and able to handle the different network characteristics including high mobility, dynamic topologies, and disconnected links. To address the existing routing protocol issues including data delay, disconnection, interference, scalability, and overhead, this paper presents the Intersection Gateway and Connectivity based Routing (IGCR) protocol for IoCV networks. The proposed protocol uses important traffic-aware routing metrics, including traffic density and direction of nodes towards the destination for route and next forwarder node selection. The experimental results indicated that the proposed protocol well-behaved and showing better performance compared to the state of the art routing protocols in terms of data delivery, data delay, and data throughput. [ABSTRACT FROM AUTHOR]

Impaired social functioning is a hallmark of schizophrenia and altered functional integration between distant brain regions are expected to account for signs and symptoms of the disorder. The functional neuroarchitecture of a network relevant for social functioning, the mentalizing network, is however poorly understood. In this study we examined dysfunctions of the mentalizing network in patients with schizophrenia compared to healthy controls via dynamic causal modelling and an interactive social decision-making game. Network characteristics were analyzed on a single subject basis whereas graph theoretic metrics such as in-degree, out-degree and edge-connectivity per network node were compared between the groups. The results point to a sparser network structure in patients with schizophrenia and highlight the dorsomedial prefrontal cortex as a disconnected network hub receiving significantly less input from other brain regions in the network. Further analyses suggest that integrating pathways from the right and the left temporo-parietal junction into the dorsomedial prefrontal cortex were less frequently found in patients with schizophrenia. Brain and behavior analyses further suggest that the connectivity-intactness within the entire network is associated with functional interpersonal behavior during the task. Thus, the neurobiological alterations within the mentalizing network in patients with schizophrenia point to a specific integration deficit between core brain regions underlying the generation of higher-order representations and thereby provide a potential treatment target. [ABSTRACT FROM AUTHOR]

In "The Short Story in Africa," Nadine Gordimer writes that the genre is more malleable and open to experimentation with style, language and form than the novel, which means that it is more easily accommodated within a variety of media spaces. Gordimer adds that the short story is "a fragmented and restless form, a matter of hit or miss, and it is perhaps for this reason that it suits modern consciousness" (170-71). Taking its cue from Gordimer's remarks, this article attempts to examine the genre of the short story through the lens of the literary prize industry in Africa. In most parts of the continent the development of the short story, like that of the novel and other genres, has been slow, facing a number of challenges such as a historically impoverished publishing industry. The rise in popularity of the local and global literary prize for the short story has however played a significant role in the promotion of the genre and literature generally on the continent. The article examines the short story's increased presence in the digital space and interrogates the general assumption on the part of many of the prize-awarding bodies that the short story can be linked to African oral traditions. The aim of the article is to explore the relationship between the genre and the rising popularity of the literary prize on the continent, focusing on the various ways in which the prize is (re)shaping the contemporary African short story. [ABSTRACT FROM AUTHOR]

Fish diversity is generally high in drainage networks in perennial systems. On the other hand, little is known about the importance of drainage networks in semiarid regions. The scant attention given to rivers in semiarid regions so far may in part be explained by the high intermittency and low ramification of these drainage networks and their incorrect classification as systems of low diversity and productivity. In this study, we investigated the importance of the drainage system of an intermittent river system in Brazil with regard to taxonomic and functional β-diversity. To do so, we evaluated the importance of both tributaries (branches) (12 sampling points) and the main stem (7 sampling points).We initially modeled the spatial structure within the branches and the main stem using asymmetric eigenvector maps. We then partitioned β-diversity values between local (biotic and abiotic) and spatial factors (positive spatial autocorrelation). The higher β-diversity values observed for branches were explained mainly by predation and environmental selection. On the other hand, in the main stem, β-diversity was best explained by a combination of environmental conditions and spatial factors. In general, local factors were more important in the functional approach than in the taxonomic approach, supporting their joint use in metacommunity studies. Our results suggest that fish metacommunity structure in branches may be responsible for maintaining regional patterns of β-diversity in semiarid river systems. [ABSTRACT FROM AUTHOR]

Highlights • First exhaustive review of WM assessed by DTI and postmortem studies in SZ and BD. • In parallel, studies confirm shared disconnectivity in SZ and BD. • Most DTI studies (8/11) found no significant difference between patient groups. • Most postmortem studies (10/12) did not show differences between patient groups. • DTI studies corroborate findings from postmortem studies in the prefrontal cortex. Abstract White matter (WM) abnormalities have implicated schizophrenia (SZ) and bipolar disorder (BD) as disconnection syndromes, yet the extent to which these abnormalities are shared versus distinct remains unclear. Diffusion tensor imaging (DTI) studies yield a putative measure of WM integrity while neuropathological studies provide more specific microstructural information. We therefore systematically reviewed all neuropathological (n = 12) and DTI (n = 11) studies directly comparing patients with SZ and BD. Most studies (18/23) reported no difference between patient groups. Changes in oligodendrocyte density, myelin staining and gene, protein and mRNA expression were found in SZ and/or BD patients as compared to healthy individuals, while DTI studies showed common alterations in thalamic radiations, uncinate fasciculus, corpus callosum, longitudinal fasciculus and corona radiata. Altogether, findings suggest shared disconnectivity in SZ and BD, which are likely related to their considerable overlap. Above all, neuroimaging findings corroborated neuropathological findings in the prefrontal cortex, demonstrating the utility of integrating multiple methodologies. Focusing on clinical dimensions over disease entities will advance our understanding of disconnectivity and help inform preventive medicine. [ABSTRACT FROM AUTHOR]

Abstract The relay node placement problem in the wireless sensor network domain has been studied extensively. But under a fixed budget, it may be impossible to procure the minimum number of relay nodes needed to design a connected network of sensor and relay nodes. Nevertheless, one would still like to design a network with high level of connectedness, or low disconnectedness. In this paper, we introduce the notion of a measure of the "connectedness" of a disconnected graph. We study a family of problems whose goal is to design a network with "maximal connectedness" subject to a fixed budget constraint. [ABSTRACT FROM AUTHOR]

"Buffers, barriers and blankets" have become recognized as increasingly important components of landscape that constrain rates of denudation. Nevertheless, connectivity continues to be emphasized in recent geomorphic discussions. It is surely the case that spatial and temporal disconnectivity is at least as common as connectivity in geomorphic sediment systems. The importance of intermittency of sediment movement events (disconnectivity over time) has been understood as fundamental in most understandings of landscape evolution. The development of new techniques that make the term connectivity more mathematically precise are much to be welcomed. But the case is argued that more progress has been made in understanding geomorphological spatial and temporal change by interrogating disconnectivity, discontinuities and thresholds. [ABSTRACT FROM AUTHOR]

Adopting an agnotological perspective, this article extends the critical literature on APIs (application programing interfaces) by systematically showing that social media APIs are largely blind to acts of disconnectivity such as unfriending and unliking. We do this through analysis of the traces of social media usage that are not accessible through APIs as gleaned from the technical documentation published for developers by 12 major SNSs. Our findings make two main contributions. First, we show for the first time that APIs offer virtually no access to data about disconnectivity. Second, we show that APIs offer a very limited historical perspective, particularly regarding disconnectivity. However, for types of users that might spend money on advertising, far more historical and disconnectivity-oriented information is accessible through the API. This has practical consequences for research and contributes to an agnotology of social media that sheds critical light on the advertiser-friendly atmosphere of connectivity that social media try to create. [ABSTRACT FROM AUTHOR]

Sediment connectivity has been shown in recent years to explain how the watershed configuration controls sediment transport. However, we find no studies develop a watershed erosion modeling framework based on sediment connectivity, and few, if any, studies have quantified sediment connectivity for gently rolling systems. We develop a new predictive sediment connectivity model that relies on the intersecting probabilities for sediment supply, detachment, transport, and buffers to sediment transport, which is integrated in a watershed erosion model framework. The model predicts sediment flux temporally and spatially across a watershed using field reconnaissance results, a high-resolution digital elevation models, a hydrologic model, and shear-based erosion formulae. Model results validate the capability of the model to predict erosion pathways causing sediment connectivity. More notably, disconnectivity dominates the gently rolling watershed across all morphologic levels of the uplands, including, microtopography from low energy undulating surfaces across the landscape, swales and gullies only active in the highest events, karst sinkholes that disconnect drainage areas, and floodplains that de-couple the hillslopes from the stream corridor. Results show that sediment connectivity is predicted for about 2% or more the watershed’s area 37 days of the year, with the remaining days showing very little or no connectivity. Only 12.8 ± 0.7% of the gently rolling watershed shows sediment connectivity on the wettest day of the study year. Results also highlight the importance of urban/suburban sediment pathways in gently rolling watersheds, and dynamic and longitudinal distributions of sediment connectivity might be further investigated in future work. We suggest the method herein provides the modeler with an added tool to account for sediment transport criteria and has the potential to reduce computational costs in watershed erosion modeling. [ABSTRACT FROM AUTHOR]

Taking the "right to disconnect" discussion as a starting point, this article considers how the im/possibility of "opting out" is ruminated in scholarly discourses on technology non-use, media resistance, and media disruption. I argue that while very different in scope, these discourses converge in that they all revolve around a structuring paradox. On one hand, this paradox is set in place by the paradox of dis/connectivity itself (no disconnectivity without connectivity). On the other hand, I argue, it is incited and reinforced by the use of scholarly methods that appear to be at odds with the gesture of disconnectivity itself, whether they be empirical, discursive, or technical (or legislative). This article stakes a claim for the importance looking at these discourses on dis/connectivity from the point of view of this structuring paradox, for it is here, I argue, that the limits of our current "culture of connectivity" are most forcefully negotiated. [ABSTRACT FROM AUTHOR]

Three themes in global mountain geomorphology have been defined and reinforced over the past decade: (a) new ways of measuring, sensing, and analyzing mountain morphology; (b) a new emphasis on disconnectivity in mountain geomorphology; and (c) the emergence of concerns about the increasing influence of anthropogenic disturbance of the mountain geomorphic environment, especially in intertropical mountains where population densities are higher than in any other mountain region. Anthropogenically induced hydroclimate change increases geomorphic hazards and risks but also provides new opportunities for mountain landscape enhancement. Each theme is considered with respect to the distinctiveness of mountain geomorphology and in relation to important advances in research over the past decade. The traditional reliance on the high energy condition to define mountain geomorphology seems less important than the presence of unique mountain landforms and landscapes and the distinctive ways in which human activity and anthropogenically induced hydroclimate change are transforming mountain landscapes. [ABSTRACT FROM AUTHOR]

In this paper I will peruse a specific cinematic example of an uncertain-image, i.e. that of the filmCreative Control(Dickinson B, dir. 2015. USA: Ghost Robot | Greencard Pictures | Mathematic | Magnolia Pictures | Amazon Studios). My interest in this film lies not, or at least not per se, or not solely, in its representationalism, but rather in its capturing of various kinds of uncertainty, to which I will here attend by situating the film against the backdrop of three different, yet interrelated, problematics related to the ubiquitous presence of digital imaging technologies: i.e., first, the concerns over digital or immaterial labour and the loss of eros; second, the use of contemporary cinematics (and the superimposition effect in particular) to address these and other issues related to living in ‘information-intensive mixed-reality environments;’ and third, the film's own suggestive counter-image, which is that of the characters’ partly defection, and, arguably, that of the image's own withdrawal from the world. [ABSTRACT FROM PUBLISHER]

This paper mainly focuses on pinning synchronization of directed networks under disconnected switching topology. Firstly, by introducing the uniformly directed spanning tree on average (UDSTA) for a time-varying digraph and designing a switching pinning controller, the asymptotic synchronization of complex networks with large number of switching topologies is investigated, in which strong connectivity and structural balance for switching topology are no longer required. Furthermore, a class of almost-period (AP) switching mode is introduced. By means of matrix decomposition, the pinning synchronization criteria of complex networks under AP switching topology are derived and the pinning nodes are selected according to maximal strongly connected root-subgraphs (MSCRSs) of average topology. Finally, a type of coupled neural networks with numerical simulations is introduced to illustrate the theoretical results. [ABSTRACT FROM AUTHOR]

The emphasis on the understanding of contemporary geomorphic processes that has dominated Anglophone geomorphological literature over the past 50 years has seen huge progress but also some set-backs. We now have reliable measurements of mean rates of operation of all subaerial processes responsible for modification of landforms and landscapes and have made good progress in estimating the role of human activities as compared with “natural” processes. Some limited progress has been achieved in understanding the scale problem but problems remain. Perhaps the single most surprising development has been the recognition of the ubiquity of disconnectivity in geomorphic systems, the need to calculate virtual velocities of whole geomorphic systems and the relevance of this understanding to the general spatio-temporal scale problem. We have always known that most geomorphic processes operate intermittently but we have continued to depend on models that imply that mass and energy move freely through geomorphic systems and that conservation of mass and energy occurrs uninterruptedly at all temporal and spatial scales.

Impaired fiber bundle connectivity between brain regions is a key neuropathological finding in schizophrenia. Symptom dimensions in schizophrenia can be clustered into factor models. Single syndromes have been related to grey and white matter brain structure alterations. We associated all core syndromes of schizophrenia in a single patient group with changes in white matter integrity. Diffusion weighted images (3T MRI) and SAPS/SANS scores were measured in 26 male patients and 26 healthy controls. First, group differences in fractional anisotropy (FA) were calculated with TBSS. Second, core symptom dimensions of schizophrenia were correlated with FA within these altered tracts. We found differences between groups in nine white matter tracts. Hallucinations were positively correlated with FA in the left uncinate fasciculus and left corticospinal tract. Ego-disturbances (passivity phenomena) showed a positive correlation with FA in the right anterior thalamic radiation. Positive formal thought disorders (FTD) corresponded negatively with FA in the right cingulum bundle. Negative symptoms were positively associated with the right anterior thalamic radiation and negatively with the right ventral cingulum bundle. For the first time, we analyzed the whole range of psychopathological factors in one schizophrenia patient group. We could validate our novel results for positive FTD and passivity phenomena by replicating findings for hallucinations and negative symptoms. Only those brain circuits which are most vulnerable at a given time during neurodevelopment are affected by a particular pathological impact (genetic, environmental). This scenario could explain the predominance of particular psychopathological syndromes related to specific white matter anomalies. [ABSTRACT FROM AUTHOR]

The emphasis on the understanding of contemporary geomorphic processes that has dominated Anglophone geomorphological literature over the past 50 years has seen huge progress but also some set-backs. We now have reliable measurements of mean rates of operation of all subaerial processes responsible for modification of landforms and landscapes and have made good progress in estimating the role of human activities as compared with "natural" processes. Some limited progress has been achieved in understanding the scale problem but problems remain. Perhaps the single most surprising development has been the recognition of the ubiquity of disconnectivity in geomorphic systems, the need to calculate virtual velocities of whole geomorphic systems and the relevance of this understanding to the general spatio-temporal scale problem. We have always known that most geomorphic processes operate intermittently but we have continued to depend on models that imply that mass and energy move freely through geomorphic systems and that conservation of mass and energy occurrs uninterruptedly at all temporal and spatial scales. [ABSTRACT FROM AUTHOR]

Given that the genetic risk for schizophrenia is highly polygenic and the effect sizes, even for rare or de novo events, are modest at best, it has been suggested that multiple biological pathways are likely to be involved in the etiopathogenesis of the disease. Most efforts in understanding the cellular basis of schizophrenia have followed a “neuroncentric” approach, focusing on alterations in neurotransmitter systems and synapse cytoarchitecture. However, multiple lines of evidence coming from genetics and systems biology approaches suggest that apart from neurons, oligodendrocytes and potentially other glia are affected from schizophrenia risk loci. Neurobiological abnormalities linked with genetic association signal could identify abnormalities that are more likely to be primary, versus environmentally induced changes or downstream events. Here, we summarize genetic data that support the involvement of oligodendrocytes in schizophrenia, providing additional evidence for a causal role with the disease. Given the undeniable evidence of both neuronal and glial abnormalities in schizophrenia, we propose a neuro-glial model that invokes abnormalities at the node of Ranvier as a functional unit in the etiopathogenesis of the disease. [ABSTRACT FROM AUTHOR]

Abstract: Property testing is concerned with constant-time algorithms for deciding whether a given object satisfies a predetermined property or is far from satisfying it. In this paper, we consider testing properties related to the connectivity of two vertices in sparse graphs. We present one-sided error testers for -disconnectivity with query complexity for digraphs and for graphs, where is an error parameter. Furthermore, we show that these algorithms are the best possible in view of query complexity, i.e., we give matching lower bounds for two-sided error testers for both cases. We also give a constant-time algorithm for testing the -disconnectivity of a directed bounded-degree hypergraph, which can be used to test the satisfiability of Horn SAT. [Copyright &y& Elsevier]

Abstract: Sedimentological connectivity within drainage systems may be controlled spatially by ‘pockets’ of intact valley fill, alluvial fans impinging laterally on mainstem rivers, floodouts impinging longitudinally on valley floors, and downstream resistant rock bands and their effect on valley width. Where local conditions favor prolonged inundation of the uppermost ~0.5 m of the sediment surface, these environments of deposition host wetlands that provide several ecosystem services to society. In this paper, we examine the long-term (millennia), large-scale mediation of connectivity by geological and geomorphological controls, highlighting the relationship between drainage disconnectivity and wetland origin, and appraise ongoing rehabilitation efforts in light of the long-term natural dynamic. The paper uses a wetland system in the KwaZulu-Natal Drakensberg Foothills, eastern South Africa, as a case study, focusing particular attention on part of the system in which cut-and-fill processes are evident, and proceeds, using observations from this and other similar wetland systems in the region, to discuss successive breaks in connectivity with increasing spatial scale and time. Implications for valley morphology are discussed, and channel incision is shown to play an important role in long-term valley and wetland morphodynamics in certain geomorphological settings, creating a diversity of geomorphological features and hydrological regimes. Thus, rehabilitation practitioners should focus on interventions that improve or stabilize desired functional outcomes, rather than on restoring or maintaining what is perceived to be ‘the natural dynamic’ in which erosion is absent. [Copyright &y& Elsevier]

Major advances continue to be made in development and application of the connectivity concept as a framework for analysis of runoff and sediment fluxes in catchments and landscapes and it is becoming a major paradigm in geomorphology and hydrology. It involves the identification of the locations and patterns of pathways of water and sediment movement and extent of their linkage. However, significant issues and challenges remain. Various approaches to identification and quantification of connectivity in a landscape are taken, involving mapping and modelling of various types. It is important in applying techniques that the purpose and basis is clear. A differentiation is made here between direct mapping of known situations, which elucidates patterns and can then be the basis for quantification, and that of modelling, which is predictive and often explanatory but requires validation. Thus, there is a synergy between the two. Various aspects of the spatial arrangements may be of interest, such as sources of sediment to a point in a catchment, pathway position, hotspots of erosion and deposition, controls on the connectivity, positions of disconnectors, influence of human activities, and natural variability with rainfall, seasons and other factors. The approach and styles of mapping usually entail recording all links at a particular time, possibly with differentiation of type of link, and commonly based on field surveys, but developments are taking place to test the effectiveness of drones for this purpose. Much modelling has used Connectivity Indices to generate patterns, with varying weighting of factors, and additional factors are now being introduced to indices to add functionality to the modelling. The other major approach to modelling is that of graph theory, based on network analysis, which is particularly applied to larger river systems. Both types of modelling have benefitted from availability of open-access software. Deficiencies and problems in use of modelling and indices persist, including: need for validation; ability to recognise disconnections; variability of connectivity over time; distinguishing sediment from flow connectivity; and clarity of representation. Challenges remain of spatial scale, particularly in validation/ field surveys but also base data for modelling; in identifying link status and functioning or dynamics at various timescales, and incorporation of feedback arising from those dynamics; in incorporating processes as a step to this functionality, and in testing indices. Methods and approaches to addressing these challenges are discussed and evaluated here. [ABSTRACT FROM AUTHOR]

• Various Connectivity Index models are tested in a Mediterranean terraced catchment. • The Index using vegetation Weighting factor simulates the field pattern best. • All the indices are poor at replicating sedimentation and disconnectivity. Connectivity analysis has proved a very valuable approach in understanding runoff and sediment fluxes in catchments. Many analyses use Connectivity Indices to model the patterns, but various versions of the Index have been developed. This paper tests the effects of these variants of the Index as applied to an agricultural-terraced catchment in the semi-arid Mediterranean region where occurrence of connectivity is relatively well documented to validate the modelling. This paper compares three versions of the Connectivity Index that use vegetation/land use (C), topography (RI) and roughness (n) as the weighting factors. Two different slope algorithms are also tested. The weightings are derived from a UAV (drone) survey, with simultaneous ground field mapping. The UAV imagery is found to provide a good, high resolution basis for determining detailed topography and vegetation cover. The slope limit present in some modelling is found to be unsuitable in this landscape where steep terrace embankments that are vegetated in places, and also partially vegetated uplands, occur. Subsequent modelling removed the slope limit. The major patterns of flow produced are similar between the models and are largely related to the overall topography and major drainage lines but considerably modified by the terracing. The model outcomes differ in detail, with the C factor model, incorporating vegetation, coming nearer to the field situation. The main deficiency in all the indices is the weakness in modelling ponding and sedimentation created by the terraces, and therefore the disconnectivity in the landscape. Comparison with field data confirms the variable connectivity in rainstorms, the effects of features such as tracks, and the effect of management actions. Evidence from field mapping during the last two decades indicates that the models probably represent the maximum possible functional connectivity. [ABSTRACT FROM AUTHOR]

Neuroimaging and electrophysiological investigations have demonstrated numerous differences in brain morphology and function of chronic schizophrenia patients compared to healthy controls. Studying patients at the beginning of their disease without the confounding effects of chronicity, medication, and institutionalization may provide a better understanding of schizophrenia. Recently, at many institutions around the world, special projects have been launched for specialized treatment and research of this interesting patient group. Using the PubMed search engine in this update, the authors summarize recent investigations between January 2002 and September 2006 that focus on whether signs of disconnectivity already exist early in the disease process. They discuss gray and white matter changes, their impact on symptomatology, electroencephalogram-based studies on connectivity, and possible influences of medication. [ABSTRACT FROM AUTHOR]

Abstract: The guarantee of perceptual coherence for events through everyday life situations depends upon the capacity to correctly integrate series of multi-sensory experiences. Patients with schizophrenia have been shown to reveal a deficit in integrating, i.e., “binding”, perceptual information together. However, results in the literature have also suggested the reverse effect. Indeed, in certain paradigms patients have revealed more binding phenomenon than healthy controls and reported experiencing two distinct events as occurring “together”. This finding suggests that patients may require longer time intervals between two distinct events before being able to perceive them as “one-after-the-other”. The question here was to test whether this perceptual binding abnormality in schizophrenia is confined to events within the same modality or whether it is also present across sensory modalities. Thirty patients with schizophrenia were compared with 33 normal controls using a simultaneity judgement paradigm. There were two uni-modal conditions in which stimuli were presented in the same modality (visual or auditory) and one bimodal condition (audio-visual). Participants were presented with stimuli varying across a range of inter-stimulus intervals (ISI). They were required to judge whether they experienced two stimuli as occurring “together” or “one-after-the-other”. Compared to controls and in all conditions, patients needed larger ISI to experience two stimuli as “one-after-the-other” (all ISI×Group interactions p <5·10−5). These abnormalities correlated with the disorganization dimension but not with the dosage of chlorpromazine equivalent. The increase of the time interval needed to perceive two stimuli as “one-after-the-other”, reflect an abnormally low time resolution in patients with schizophrenia. We discuss the possible involvement of anatomical disconnectivity in schizophrenia which would specifically affect the time integration properties of neural assemblies. [Copyright &y& Elsevier]

Abstract: Cortical ‘disconnection’, involving disruption of white matter tracts in the brain, has been hypothesized as a mechanism of age-related cognitive decline. Diffuse hyperintensities in the white matter (so called white matter hyperintensities, WMH) on T2-weighted MRI scans are regarded to represent ischemic damage of the subcortical fiber system and are found to be increased with advanced age. In the present study, we examined whether WMH might be a mediating factor for age-effects in dichotic listening. For that purpose, we examined the association between age, deep or subcortical white matter hyperintensities (DWMH), periventricular hyperintensities (PVH) and dichotic listening performance in healthy older adults with ages ranging from 50 to 81 years. We found decreased dichotic listening performance with increasing age, specifically for the left ear (LE) but not the right ear (RE) in a standard unbiased-attention condition, and for the unattended ears but not the attended ears in conditions in which attention was controlled. Interestingly, hierarchical regression analyses revealed that the age-effect is partially mediated by DWMH specifically in the hemisphere contralateral to the attended ear. Moreover, we found indications that RE performance is specifically affected by DWMH in the right and left frontal and temporal areas, and that LE performance is mostly affected by DWMH selectively in the left hemisphere, including the left temporal area. The present study underlines the idea that disconnectivity is involved in age-related cognitive decline. [Copyright &y& Elsevier]

Abstract: Catchment configuration and the nature of connectivity within and between landscape compartments affect the operation of sediment cascades and geomorphic responses to disturbance events of differing magnitude and frequency. This paper introduces the concept of landform impediments, termed buffers, barriers and blankets, that impede sediment conveyance by limiting the connectivity between landscape compartments. Buffers restrict sediment delivery to channels, barriers inhibit sediment movement along channels, and blankets drape channel or floodplain surfaces affecting the accessibility of sediment to entrainment. These features operate as a series of switches which turn on/off processes of sediment delivery, determining the effective catchment area at any given time. Using previously documented examples, the role of these features in affecting the operation of sediment cascades in a low relief, passive landscape setting such as the Australian landmass is contrasted to examples from high relief, uplifting settings in New Zealand. The Australian examples are further explored by examining how changes to landscape connectivity brought about by human disturbance since European settlement have impacted upon landscape sensitivity and prospects for river recovery. This approach to analysis of impediments to sediment conveyance is generic and can be applied in any environmental setting. [Copyright &y& Elsevier]

Abstract: (Dis)connectivity within and between landscape compartments affects the extent and rate of transfer of energy and matter through catchments. Various landforms may impede sediment conveyance in a river system, whether laterally to the channel (termed buffers) or longitudinally along the channel itself (termed barriers). A generic approach to analysis of landscape (dis)connectivity using slope threshold analysis in GIS, tied to air photograph interpretation and field mapping of buffers and barriers, is tested in the upper Hunter catchment, Australia. Under simulated conditions, effective catchment area, which is a measure of the proportion of a catchment that has the potential to contribute sediment to the channel network, varies from 73% to just 3% of the total catchment area for differing subcatchments in the upper Hunter. This variability can be explained by the spatial distribution and assemblage of buffers and barriers in each subcatchment. Multiple forms of disconnectivity are evident in some subcatchments, such that when one buffer or barrier is breached, other features still impede sediment transfer within the system. The importance of the position of buffers and barriers within any given subcatchment is emphasised. Spatial variability in valley width exerts a critical control on catchment connectivity, with more efficient sediment conveyance in narrow valleys relative to wider valleys characterised by piedmonts, terraces, fans and extensive floodplains in which conveyance is impeded. This variability reflects the landscape history and geological setting of each subcatchment. The framework developed in this paper can be used to assess the impact of natural or human-induced buffers and barriers on catchment-scale sediment flux in any landscape setting, providing a physical template atop which other biogeochemical fluxes could be examined. [Copyright &y& Elsevier]

Geographic concerns for spatial relationships lie at the heart of geomorphic applications in environmental management. The way in which landscape compartments fit together in a catchment influences the operation of biophysical fluxes, and hence the ways in which disturbance responses are mediated over time. These relationships reflect the connectivity of the landscape. A nested hierarchical framework that emphasizes differing forms of (dis)connectivity in catchments is proposed. This field-based geomorphic tool can be used to ground the application of modelling techniques in analysis of catchment-scale biophysical fluxes. [ABSTRACT FROM AUTHOR]

It is generally agreed that quantum mechanics (QM) describes brilliantly the behavior of matter at the atomic and subatomic level. However, many people, including the author, believe that if it is taken seriously at the level of everyday life, it leads to insuperable difficulties, exemplified by the fate of Schrödinger's unfortunate cat. If, therefore, one is prepared to envisage seriously the possibility that if QM is pushed sufficiently far it may break down or have to be supplemented by some new and currently unforeseeable principle, then the obvious axis along which to try to “push” it is that which brings us closest to the world of everyday life. Thus, we are motivated to try to define which exact feature most sharply distinguishes those applications of QM at the everyday level that appear paradoxical: to seek, in fact, a quantitative measure of the degree of “Schrödinger's-cattiness” of various physical situations. Although this is no doubt a subjective question, I explore two plausible candidates: one involving the divergence, in the two branches of the (notional) quantum superposition, of some “macroscopic” physical quantity; the other invoking the idea of “disconnectivity”a notion that has much in common with the concept of “degree of entanglement” currently employed in the context of EPR-Bell-type experiments. Having tried to isolate and define the “axis” along which we are trying to push QM, I then discuss the main generic obstacles to this program, which may be summarized as (1) quasi-classicality, (2) decoherence, and (3) Franck-Condon suppression. Finally, I emphasize the importance not only of verifying (or not) that QM continues to predict correctly the experimental behavior as we progress along the relevant axis, but of confronting its predictions with those of a class of alternative, “macrorealistic” theories. I comment on the implications of various possible outcomes to this confrontation. [ABSTRACT FROM AUTHOR]