Loss Of Connectivity Research Articles

Zinc Oxide Nanoparticles (ZnO-NPs) Induce Cytotoxicity in the Zebrafish Olfactory Organs via Activating Oxidative Stress and Apoptosis at the Ultrastructure and Genetic Levels.

Nanotechnology has gained tremendous attention because of its crucial characteristics and wide biomedical applications. Although zinc oxide nanoparticles (ZnO-NPs) are involved in many industrial applications, researchers pay more attention to their toxic effects on living organisms. Since the olfactory epithelium is exposed to the external environment, it is considered the first organ affected by ZnO-NPs. Herein, we demonstrated the cytotoxic effect of ZnO-NPs on the olfactory organ of adult zebrafish after 60 days post-treatment. We opted for this period when fishes stop eating their diet from the aquarium, appear feeble, and cannot swim freely. Our study demonstrated that ZnO-NPs induced significant malformations of the olfactory rosettes at histological, ultrastructural, and genetic levels. At the ultrastructure level, the olfactory lamellae appeared collapsed, malformed, and twisted with signs of degeneration and loss of intercellular connections. In addition, ZnO-NPs harmed sensory receptor and ciliated cells, microvilli, rodlet, crypt, and Kappe cells, with hyper-activity of mucous secretion from goblet cells. At the genetic level, ZnO-NPs could activate the reactive oxygen species (ROS) synthesis expected by the down-regulation of mRNA expression for the antioxidant-related genes and up-regulation of DNA damage, cell growth arrest, and apoptosis. Interestingly, ZnO-NPs affected the odor sensation at 60 days post-treatment (60-dpt) more than at 30-dpt, severely damaging the olfactory epithelium and irreparably affecting the cellular repairing mechanisms. This induced a dramatically adverse effect on the cellular endoplasmic reticulum (ER), revealed by higher CHOP protein expression, that suppresses the antioxidant effect of Nrf2 and is followed by the induction of apoptosis via the up-regulation of Bax expression and down-regulation of Bcl-2 protein.

P01.01.A THE IMPACT OF BRAIN LESIONS ON HEALTH-RELATED QUALITY OF LIFE IN PATIENTS WITH WHO CNS GRADE 3 OR 4 GLIOMA: A LESION-FUNCTION AND RESTING-STATE FMRI ANALYSIS

Abstract BACKGROUND In glioma patients, tumor development and multimodality therapy are associated with changes in health-related quality of life (HRQoL). It is largely unknown how different types and locations of tumor- and treatment-related brain lesions, as well as their relationship to white matter tracts and functional brain networks, affect HRQoL. MATERIAL AND METHODS In 121 patients with pretreated gliomas of WHO CNS grades 3 or 4, structural MRI, O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET, resting-state functional MRI (rs-fMRI) and self-reported HRQoL questionnaires (EORTC QLQ-C30/BN20) were obtained. Resection cavities, T1-enhancing lesions, T2/FLAIR hyperintensities, and lesions with pathologically increased FET uptake were delineated. Effects of tumor lateralization, involvement of white matter tracts or resting-state network nodes by different types of lesions and within-network rs-fMRI connectivity were analyzed in terms of their interaction with HRQoL scores. RESULTS Right hemisphere gliomas were associated with significantly less favorable outcomes in physical, role, emotional and social functioning, compared with left-sided tumors. Most functional HRQoL scores correlated significantly with right-sided white-matter tracts involvement by T2/FLAIR hyperintensities and with loss of within-network functional connectivity of right-sided nodes. Tumors of the left hemisphere caused significantly more communication deficits. CONCLUSION In pretreated high-grade gliomas, right hemisphere lesions are associated with reduced HRQoL scores in most functional domains except communication ability, compared to tumors of the left hemisphere. These relationships are mainly observed for T2/FLAIR lesions involving structural and functional networks in the right hemisphere. The data suggest that sparing the right hemisphere from treatment-related tissue damage may improve HRQoL in glioma patients.

The effects of longitudinal fragmentation on riverine beta diversity are modulated by fragmentation intensity

The loss of longitudinal connectivity affects river systems globally, being one of the leading causes of the freshwater biodiversity crisis. Barriers alter the dispersal of aquatic organisms and limit the exchange of species between local communities, disrupting metacommunity dynamics. However, the interplay between connectivity losses due to dams and other drivers of metacommunity structure, such as the configuration of the river network, needs to be explored. In this paper, we analyzed the response of fish communities to the network position and the fragmentation induced by dams while controlling for human pressures and environmental gradients. We studied three large European catchments covering a fragmentation gradient: Upper Danube (Austrian section), Ebro (Spain), and Odra/Oder (Poland). We quantified fragmentation through reach-scaled connectivity indices that account for the position of barriers along the dendritic network and the dispersal capacity of the organisms. We used generalized linear models to explain species richness and Local Contributions to Beta Diversity (LCBD) and multilinear regressions on the distance matrix to describe Beta Diversity and its Replacement and Richness Difference components. Results show that species richness was not affected by fragmentation. Network centrality metrics were relevant drivers of beta diversity for catchments with lower fragmentation (Ebro, Odra), and fragmentation indices were strong beta diversity predictors for the catchment with higher fragmentation (Danube). We conclude that in highly fragmented catchments, the effects of network centrality/isolation on biodiversity could be masked by the effects of dam fragmentation. In such catchments, metapopulation and metacommunity dynamics can be strongly altered by barriers, and the restoration of longitudinal connectivity (i.e. the natural centrality/isolation gradient) is urgent to prevent local extinctions.

Neurodegeneration or dysfunction in Phelan-McDermid syndrome? A multimodal approach with CSF and computational MRI

BackgroundPhelan-McDermid syndrome (PMS) is a rare multisystem disease with global developmental delay and autistic features. Genetically, the disease is based on a heterozygous deletion of chromosome 22q13.3 with involvement of at least part of the SHANK3 gene or heterozygous pathogenic variants in SHANK3. Pathophysiologically, this syndrome has been regarded as a synaptopathy, but current data suggest an additional concept, since axonal functions of neurons are also impaired, thus, the specific pathophysiological processes in this disease are not yet fully understood. Since symptoms of the autism spectrum, regression, and stagnation in development occur, we investigated whether neuroinflammatory and neurodegenerative processes may also play a role. To this end, we analysed biomarkers in cerebrospinal fluid (CSF) and parameters from magnetic resonance imaging with high-resolution structural T1w volumetry and diffusion tensor imaging analysis in 19 Phelan-McDermid syndrome patients.ResultsCSF showed no inflammation but abnormalities in tau protein and amyloid-ß concentrations, however, with no typical biomarker pattern as in Alzheimer’s disease. It could be demonstrated that these CSF changes were correlated with integrity losses of the fibres in the corticospinal tract as well as in the splenium and dorsal part of the cingulum. High CSF levels of tau protein were associated with loss of integrity of fibres in the corticospinal tract; lower levels of amyloid-ß were associated with decreasing integrity of fibre tracts of the splenium and posterior cingulate gyrus. Volumetric investigations showed global atrophy of the white matter, but not the grey matter, and particularly not in temporal or mesiotemporal regions, as is typical in later stages of Alzheimer’s disease.ConclusionsIn summary, alterations of neurodegenerative CSF markers in PMS individuals could be demonstrated which were correlated with structural connectivity losses of the corticospinal tract, the splenium, and the dorsal part of the cingulum, which can also be associated with typical clinical symptoms in these patients. These findings might represent a state of dysfunctional processes with ongoing degenerative and regenerative processes or a kind of accelerated aging. This study should foster further clinical diagnostics like tau- and amyloid-PET imaging as well as novel scientific approaches especially in basic research for further mechanistic proof.

Wnt signaling in synaptogenesis of Alzheimer's disease.

Alzheimer's disease (AD), recognized as the leading cause of dementia, occupies a prominent position on the list of significant neurodegenerative disorders, representing a significant global health concern with far-reaching implications at both individual and societal levels. The primary symptom of Alzheimer's disease is a decrease in synaptic potency along with synaptic connection loss. Synapses, which act as important linkages between neuronal units within the cerebral region, are critical in signal transduction processes essential to orchestrating cognitive tasks. Synaptic connections act as critical interconnections between neuronal cells inside the cerebral environment, facilitating critical signal transduction processes required for cognitive functions. The confluence of axonal and dendritic filopodial extensions culminates in the creation of intercellular connections, coordinated by various signals and molecular mechanisms. The progression of synaptic maturation and plasticity is a critical determinant in maintaining mental well-being, and abnormalities in these processes have been linked to the development of neurodegenerative diseases. Wnt signaling pathways are important to the orchestration of synapse development. This review examines the complicated interplay between Wnt signaling and dendritic filopodia, including an examination of the regulatory complexities and molecular machinations involved in synaptogenesis progression. Then, these findings are contextualized within the context of AD pathology, allowing for the consideration of prospective therapeutic approaches based on the findings and development of novel avenues for future scientific research.

Advancing 5G Connectivity: A Comprehensive Review of MIMO Antennas for 5G Applications

The review focuses on the emergence of 5G wireless communication and the need for multiple-input multiple-output antennas to support high-speed communication systems. The article discusses the advantages of MIMO antennas, including increased channel capacity and the ability to focus radio frequency energy on specific users. However, the challenges of creating compact MIMO antennas with ideal isolation are addressed, including short wavelengths, connection losses, constrained bandwidth, and path losses in the millimeter-wave range. Design techniques and methods to enhance the performance of conventional antennas for 5G applications are discussed, along with potential solutions for upcoming challenges. The article provides an overview of MIMO antennas for 5G applications, covering frequency bands, system architecture, advantages, challenges, advancements, performance enhancement techniques, design techniques, and state-of-the-art developments.

Age-related differences in the functional topography of the locus coeruleus and their implications for cognitive and affective functions.

The locus coeruleus (LC) is an important noradrenergic nucleus that has recently attracted a lot of attention because of its emerging role in cognitive and psychiatric disorders. Although previous histological studies have shown that the LC has heterogeneous connections and cellular features, no studies have yet assessed its functional topography in vivo, how this heterogeneity changes over aging, and whether it is associated with cognition and mood. Here, we employ a gradient-based approach to characterize the functional heterogeneity in the organization of the LC over aging using 3T resting-state fMRI in a population-based cohort aged from 18 to 88 years of age (Cambridge Centre for Ageing and Neuroscience cohort, n=618). We show that the LC exhibits a rostro-caudal functional gradient along its longitudinal axis, which was replicated in an independent dataset (Human Connectome Project [HCP] 7T dataset, n=184). Although the main rostro-caudal direction of this gradient was consistent across age groups, its spatial features varied with increasing age, emotional memory, and emotion regulation. More specifically, a loss of rostral-like connectivity, more clustered functional topography, and greater asymmetry between right and left LC gradients was associated with higher age and worse behavioral performance. Furthermore, participants with higher-than-normal Hospital Anxiety and Depression Scale (HADS) ratings exhibited alterations in the gradient as well, which manifested in greater asymmetry. These results provide an in vivo account of how the functional topography of the LC changes over aging, and imply that spatial features of this organization are relevant markers of LC-related behavioral measures and psychopathology.

Age-related differences in the functional topography of the locus coeruleus and their implications for cognitive and affective functions

The locus coeruleus (LC) is an important noradrenergic nucleus that has recently attracted a lot of attention because of its emerging role in cognitive and psychiatric disorders. Although previous histological studies have shown that the LC has heterogeneous connections and cellular features, no studies have yet assessed its functional topography in vivo, how this heterogeneity changes over aging, and whether it is associated with cognition and mood. Here, we employ a gradient-based approach to characterize the functional heterogeneity in the organization of the LC over aging using 3T resting-state fMRI in a population-based cohort aged from 18 to 88 years of age (Cambridge Centre for Ageing and Neuroscience cohort, n=618). We show that the LC exhibits a rostro-caudal functional gradient along its longitudinal axis, which was replicated in an independent dataset (Human Connectome Project [HCP] 7T dataset, n=184). Although the main rostro-caudal direction of this gradient was consistent across age groups, its spatial features varied with increasing age, emotional memory, and emotion regulation. More specifically, a loss of rostral-like connectivity, more clustered functional topography, and greater asymmetry between right and left LC gradients was associated with higher age and worse behavioral performance. Furthermore, participants with higher-than-normal Hospital Anxiety and Depression Scale (HADS) ratings exhibited alterations in the gradient as well, which manifested in greater asymmetry. These results provide an in vivo account of how the functional topography of the LC changes over aging, and imply that spatial features of this organization are relevant markers of LC-related behavioral measures and psychopathology.

The Mythologeme “Home” in the works of Russian Emigration writers of the Second Wave (using the example of R. Berezov’s works).

The article is devoted to the representation of the image of home, one of the dominants of Russian culture, in the works of émigré writers. In the literature of the Russian emigration, it acquires a special tragic character and is interpreted differently by representatives of different waves. However, one can single out typological features that unite émigré writers: autobiographical narrative, nostalgic motifs in the depiction of Russia, apocalyptic perception of the loss of connection with home. The analysis of the work of Rodion Berezov, a representative of the second wave, reveals the main ways of implementing the mythologeme in the prose of post-war emigration and allows us to trace the transformation of the perception of the loss of home by emigrants of different waves. The novelty of the study is due to the lack of literature studies of the second wave of emigration in the context of this issue.

Redox Tolerant Solid Oxide Electrolysis Cathode for CO2 and Steam

The production of oxygen for life support and ascent vehicle propellant oxidant is essential for human expeditions to Mars. OxEon team led the development of solid oxide electrolysis cell (SOEC) stacks for the Mars 2020 mission in collaboration with the Jet Propulsion Laboratory (JPL) and Massachusetts Institute of Technology (MIT). A stack that was installed in the Perseverance Rover has been operated twelve times so far to demonstrate the production of high purity oxygen by electrolyzing Mars atmosphere CO2.Traditionally, SOEC stacks use nickel–zirconia or nickel–ceria composite cathode to reduce the oxidized species. Nickel based electrodes are susceptible to oxidation by the feed gas (CO2 or steam) at the inlet conditions and are often irreversibly damaged during operation and start-up unless reduced species (carbon monoxide or hydrogen) are also present. Oxidation of Ni to NiO causes ~24% volume expansion, and a redox cycle with associated expansion and contraction can result in significant changes to the microstructure and loss of connectivity in the cathode and current collection layers. This challenge was encountered during early stack and testing development for the Mars mission where even short-term exposure to oxidizing dry CO2 feed caused massive performance degradation (12% of initial performance after 15 operational cycles). This necessitated a recycle loop for the stack on the Perseverance Rover that introduces a fraction of the CO-containing tail gas to the inlet to protect the cathode layers from oxidation.A simpler solution than a system recycle loop was desired for future applications. Under a NASA SBIR program OxEon investigated a combination of materials and engineering solutions to improve redox tolerance of the nickel-based cathode so that 100% dry CO2 could be fed directly into a stack without harming the electrode. A modified nickel-based cathode composition with a unique backbone and infiltrated cathode structure was developed and tested in both button cell and stack configurations. The new cathode has been shown to completely tolerate partial and full (i.e., complete oxidation of Ni to NiO before re-reduction) redox cycling, with complete performance recovery occurring in a matter of minutes even after total oxidation. It was also demonstrated that feeding a reducing gas after complete oxidation is not required since the CO generated by the applied voltage during initial CO2 electrolysis reaction is sufficient for self-reduction recovery. This self-recovery feature is particularly attractive for applications where an oxidizing gas feed cannot be easily substituted with a reducing gas feed, such as with Mars O2 generation.In-situ resource utilization (ISRU) of lunar ice and potential Martian ice for O2 and H2 generation is also of significant interest for future space missions. The redox tolerant cathode has been shown to completely tolerate steam oxidation as well, with self-generated H2 resulting in rapid reduction and recovery. Steam redox tolerance was demonstrated in both button cells and stacks and was independently verified by testing at PNNL. The redox tolerant cathode is also capable of rapid thermal cycling with ramp rates as high as 15 °C/min tested with no performance degradation. Improved coking tolerance over the traditional cathode material is an additional robustness feature that allows for higher conversion of CO2, enabling increased O2 production.This work was done under a NASA Small Business Innovation Research Contract No. 80NSSC19C0114. Validation testing at PNNL was performed under a DOE Award No. DE-FE0032105.

(Digital Presentation) Approaches of Pre-Lithiation on Si Anode for Lithium-Ion Batteries

Silicon is one of the most attractive anode materials for next generation high-capacity lithium-ion batteries (LIBs) due to its high specific capacity. However, the large volume change (up to 300%) of silicon during lithiation/delithiation process leads to coupled mechanical and chemical degradation, such as pulverization of silicon particles, formation of unstable solid-electrolyte interphase (SEI), and loss of electrical connectivity, resulting in high irreversible capacity loss and rapid capacity fading. Pre-lithiation is one of the effective approaches to compensate for the loss of active lithium and extend battery cycle life. In this work, various approaches of pre-lithiation for Si electrodes are systematically studied and compared. Different levels of pre-lithiation dosage are applied to the Si electrodes and the pre-lithiated Si electrodes are evaluated in NMC622/Si full cell configuration. After pre-lithiation, the cell capacity and cycling stability are significantly improved. The impacts of operating voltage window, and N/P ratio on electrochemical performance are also investigated. The morphology of pre-lithiated Si electrodes before and after cycling are also compared via cross section scanning electron microscopy (SEM) to understand the electrode expansion and SEI formation/growth during cycling.

Female Higher Education Students’ Lived Experiences during the COVID-19 Pandemic: The Case Study Viewed through a Phenomenological Lens

This paper examines the subjective realities of female students in higher education as they navigated their well-being and active lives during the COVID-19 pandemic. Drawing upon Merleau-Ponty’s phenomenological framework, which confronts an often-neglected dimension of our experience—the lived body and the phenomenal world—we aim to inform the development of targeted support and interventions to address the specific needs of female students, in future pandemic times. By exploring how three female students studying sport and recreation in higher education perceived their experiences, this article seeks to shed light on the unique challenges faced by these women in maintaining physical activity, coping with isolation and a change in social networks, and managing their mental health in the context of the pandemic. Understanding these subjective realities (such as isolation, restricted physical activity, and loss of social connections) and interpreting the three students’ lived habitats, their bodily responsiveness, and their spontaneity ensures that their experience is heard, and appropriate future support can be given.

The silent extinction of freshwater mussels in Portugal

Freshwater mussels are one of the most threatened animal groups in the world. In the European Union, threatened and protected mussel species are not adequately monitored, while species considered to be common and widespread receive even less attention. This is particularly worrying in the Mediterranean region, where species endemism is high and freshwater habitats are severely affected by water scarcity. In the absence of hard data on population trends, we report here a long-term comparison of freshwater mussel assemblages at 132 sites covering 15 different hydrological basins in Portugal. This study reveals a widespread decline of 60 % in the number of sites and 67 % in the overall abundance of freshwater mussels across Portugal over the last 20 years, indicating that all species are rapidly declining and threatened with extinction. These results show that current legislation and conservation measures are largely ineffective and highlight the importance of updating the Habitats Directive to enforce standard monitoring protocols for threatened species in the European Union and to extend monitoring to other freshwater species thought to be common and widespread. Efficient water management, restrictions on irrigation expansion in important biodiversity areas, mitigation of hydrological changes and loss of aquatic habitat connectivity caused by physical alterations are urgently needed to reverse these declining population trends. For the severely endangered species Margaritifera margaritifera, Potomida littoralis, and Unio tumidiformis, where populations are now critically low, more urgent action is needed, such as ex-situ conservation, protection of remaining populations and large-scale habitat restoration.

High-performance optical phased array for LiDARs demonstrated by monolithic integration of polymer and SiN waveguides.

Optical phased array (OPA) beam scanners for light detection and ranging (LiDAR) are proposed by integrating polymer waveguides with superior thermo-optic effect and silicon nitride (SiN) waveguides exhibiting strong modal confinement along with high optical power capacity. A low connection loss of only 0.15 dB between the polymer and SiN waveguides was achieved in this work, enabling a low-loss OPA device. The polymer-SiN monolithic OPA demonstrates not only high optical throughput but also efficient beamforming and stable beam scanning. This novel integrative approach highlights the potential of leveraging heterogeneous photonic materials to develop advanced photonic integrated circuits with superior performance.

Exploring functional flow heterogeneity in regulated flow regime: Fish species turnover along hydraulic gradients in an artificial waterway network

AbstractHumans have altered river flows leading to a loss of connection with floodplain habitats. The expansion of agriculture in floodplains has resulted in landscapes dominated by irrigated farmland. A key challenge in water management is to conserve existing ecological communities and habitat heterogeneity, while simultaneously maintaining engineered infrastructure for agriculture. In this study, we focused on an artificial channel network for irrigation with a regulated flow regime and its function as habitat for various fish species. Differences in hydraulic conditions among channels and compositional changes in fish species were examined to clarify functional flow heterogeneity. Analyzed using pairwise Simpson dissimilarity among sampling reaches, species turnover was positively associated with Froude number (flow intensity) differences at intermediate discharges, and with differences in cross‐sectional areas (flow magnitude) at low discharges. Drastic changes in inflows should be considered for the effective conservation of flow heterogeneity, even under a regulated flow regime. Improved engineering design to manage the hydraulic environment is one option for maintaining the ecological value of lateral waterbodies in human‐dominated landscapes. Our findings provide insights into the importance of functional flow heterogeneity to conserve fish species diversity.

Social therapy as a technology of social work with children from families in difficult life situations

A difficult life situation is a situation that means the experiences of people who find themselves in circumstances that seriously affect their well-being, the safety of life, and from which they are not always able to get out on their own. Children who find themselves in a difficult life situation are especially in need of help. The paper identifies the most significant factors affecting family well-being, as a result of which children may have a difficult life situation: poor financial conditions in the family, loss of connection with the labor market, intra-family conflicts, an unfavorable psychological atmosphere in the family, cruel treatment in the family, etc. The essence of social therapy as a specific technology of social work is that it is based on the idea of «treatment», i.e. achieving the highest possible level of human social health, primarily the normal functioning and adaptation of persons with physical and psychological pathology. Social therapy includes various methods aimed at achieving social well-being by family members, including children. It can be group and individual one. Examples of social therapy methods are bibliotherapy, fairy tale therapy, music therapy, occupational therapy, cinema therapy, sandplay therapy, etc.

Vulnerability assessment of critical infrastructures for cascading failures: An application to water distribution networks

Critical infrastructures form the backbone of any nation, and the failures of these infrastructures could lead to economic disruptions and fatal consequences. Assessing the vulnerability of such critical infrastructures has now evolved into a necessary and imperative task for researchers around the world. Water distribution networks form an essential class of critical infrastructures of modern society. The uninterrupted functioning of such networks is crucial for ensuring a nation’s economic development and welfare of society. The objective of this article is to evaluate the vulnerability of nodes for Water Distribution Networks considering cascading failures. The system dynamics of a water network are included in the simulation process to estimate the impacts of cascading failures. Vulnerability metrics based on loss of topological connectivity and supply capability are formulated in this article. The applicability and significance of the proposed methodology are demonstrated using a sample network case study. Identification of different vulnerability zones is done by employing k-means clustering to perform a methodical comparison between the proposed and existing metrics of vulnerability assessment.

Promoting trust in HAVs of following manual drivers through implicit and explicit communication during minimal risk maneuvers

The successful integration of highly automated vehicles (HAV) in future mixed traffic environments will depend, among other things, on their seamless, safe, and accepted interaction with other road users. Therefore, appropriate combination of light signals, as external human-machine interface (eHMI), and driving behavior, as dynamic human-machine interface (dHMI), is required consistently in order to develop trust of following manual drivers in HAVs. Especially, in borderline traffic scenarios where HAVs are confronted with challenges, such as loss of connectivity, so-called minimal risk maneuvers (MRMs) are performed abruptly. Here, understanding communication via eHMI and dHMI is crucial for road safety, as drivers need to prepare for maneuvers themselves. Therefore, two consecutive, explorative online video studies were conducted. Firstly, the appropriate braking dynamics for an MRM were evaluated. Secondly, insights into the eHMI communication strategy of an HAV during an MRM were gained. The overall aim of this work is to present strategies for implicit and explicit communication channels of an HAV in order to promote learned trust during MRMs from the perspective of drivers who follow them. The results show that adding novel eHMI designs (e.g., warning sign, 360° LED light-band) to conventional light signals positively affects the user experience in a first contact interaction. The findings could have a positive impact on the development of trust in HAVs. In conclusion, specific eHMI communication strategies can be highly supportive for following manual drivers in MRM scenarios, which may lead to legislative considerations in the future.

Adaptive Coordinated Direct and Multi-RIS Transmissions for Ultrareliable Terahertz Systems

This paper investigates the outage probability of an adaptive coordinated direct and multi-RIS transmission for TeraHertz (THz) communication systems. Specifically, to tackle the connection loss due to pointing errors and severe attenuation in THz band, we propose two schemes that make use of a multi-RIS communication as a backup link to improve the reliability of the direct one. Invoking the two multi-RIS schemes, namely, the cooperative RIS (CR) and the opportunistic RIS (OR) schemes, exact and asymptotic outage expressions are obtained while accounting for small scale fading and non-zero boresight pointing errors. The accuracy of the analytical results is validated with Monte-Carlo simulations. The obtained results recognize a clear advantage of the proposed system compared with conventional standalone direct THz link. Thus, with carefully planned networks, enabling direct and multi-RIS cooperation for THz wireless systems can maintain sufficient coverage in sixth-generation (6G) networks.

Performance Analysis of TCP Fractional Window Increment and Adaptive Fractional Window on IEEE 802.11 Multihop Ad Hoc Networks

TCP, a layer 4 transport protocol, plays a crucial role in both wireless and wired networks. However, its performance in wireless networks is often unsatisfactory due to issues such as bandwidth limitations and utility problems with lower network layers. The mobility effect further exacerbates TCP's performance, as it fails to distinguish between connection failure and congestion-induced connection loss. In response to this challenge, researchers have explored potential solutions and found that TCP FeW outperforms the existing TCP NewReno. Building upon this background, this paper aims to simulate and analyze the performance of TCP AFW and TCP FeW in an IEEE 802.11 network. The simulations conducted using ns2 in a limited environment with random mobile scenarios reveal that TCP AFW achieves a 1.12% higher throughput compared to FeW, even with minimal modifications.