The phenomenal growth of mobile data demand has brought about increasing scarcity in available radio spectrum. Meanwhile, mobile customers pay more attention to their own experience, especially in ...communication reliability and service continuity on the move. To address these issues, LTE-Unlicensed, or LTEU, is considered one of the latest groundbreaking innovations to provide high performance and seamless user experience under a unified radio technology by extending LTE to the readily available unlicensed spectrum. In this article, we offer a comprehensive overview of the LTEU technology from both operator and user perspectives, and examine its impact on the incumbent unlicensed systems. Specifically, we first introduce the implementation regulations, principles, and typical deployment scenarios of LTE-U. Potential benefits for both operators and users are then discussed. We further identify three key challenges in bringing LTE-U into reality together with related research directions. In particular, the most critical issue of LTE-U is coexistence with other unlicensed systems, such as widely deployed WiFi. The LTE/WiFi coexistence mechanisms are elaborated in time, frequency, and power aspects, respectively. Simulation results demonstrate that LTE-U can provide better user experience to LTE users while well protecting the incumbent WiFi users' performance compared to two existing advanced technologies: cellular/WiFi interworking and licensed-only heterogeneous networks (Het-Nets).
► Multipurpose greenway is a proven strategy for sustainable urban development. ► We present an improved approach for developing comprehensive greenway networks. ► Priority networks effectively ...coordinate goals across different levels of management. ► Modified LCP model increases the validity of the simulation results. ► The proposed networks combine nature protection and recreation needs in Wuhan, China.
Urban greenways are proven strategies to counter ecological fragmentation and improve urban sustainability. However, significant challenges remain when seeking to integrate multiple functions into priority-oriented planning. In this paper, we focus on the city of Wuhan (China) to present an innovative approach for developing multi-functional greenway networks. Based on remote sensing and geographical information systems, this approach applies a least-cost path model, a kernel density analysis and a proxy index to identify and integrate multiple needs into priority greenway networks. Our priorities are bird and small mammal conservation, human recreation and water protection. In the cost settings of the least-cost path model, we include simulated construction costs to realistically identify corridors. This method insures that our results reflect the expenses necessary for the construction of greenways. Our study demonstrates that the kernel density method is an effective tool to illustrate priorities by revealing the potential utilisation intensity of corridors. Based on the proposed method, we identify eight potential greenway networks, each highlighting different sets of priorities. We divide these priority greenway networks into three categories of ecological security: ideal greenways, backbone greenways and the comprehensive greenway network. The latter represents the integration of animal conservation, human recreation and water protection objectives. Because priorities can be added, interchanged or weighted according to local specificities, our study offers a methodological framework applicable to developing and developed cities.
Recent advances in microelectromechanical system (MEMS) technology have boosted the deployment of wireless sensor networks (WSNs). Limited by the energy storage capability of sensor nodes, it is ...crucial to jointly consider security and energy efficiency in data collection of WSNs. The disjoint multipath routing scheme with secret sharing is widely recognized as one of the effective routing strategies to ensure the safety of information. This kind of scheme transforms each packet into several shares to enhance the security of transmission. However, in many-to-one WSNs, shares have high probability to traverse through the same link and to be intercepted by adversaries. In this paper, we formulate the secret-sharing-based multipath routing problem as an optimization problem. Our objective aims at maximizing both network security and lifetime, subject to the energy constraints. To this end, a three-phase disjoint routing scheme called the Security and Energy-efficient Disjoint Route (SEDR) is proposed. Based on the secret-sharing algorithm, the SEDR scheme dispersively and randomly delivers shares all over the network in the first two phases and then transmits these shares to the sink node. Both theoretical and simulation results demonstrate that our proposed scheme has significant improvement in network security under both scenarios of single and multiple black holes without reducing the network lifetime.
Freshwater gastropods are widely distributed and play an important role in aquatic ecosystems. Symbiotic microorganisms represented by gut microbes can affect the physiological and biochemical ...activities of their hosts. However, few studies have investigated the response of the gut microbial community of snails to environmental stress. In this study, the dynamics of the gut microbiota of the gastropod
were tracked to explore their responses in terms of their composition and function to cyanobacterial bloom. Differences in gut microbial community structures during periods of non-cyanobacterial bloom and cyanobacterial bloom were determined. Results showed that the alpha diversity of the gut microbiota exposed to cyanobacterial bloom was lower than that of the gut microbiota exposed to non-cyanobacterial bloom. The main genera differentiating the two periods were
, and
. Microcystins (MCs) and water temperature (WT) were the primary factors influencing the gut microbial community of
; between them, the influence of MCs was greater than that of WT. Fourteen pathways (level 2) were notably different between the two periods. The pathways of carbohydrate metabolism, immune system, environmental adaptation, and xenobiotics biodegradation and metabolism in these differential pathways exhibited a strong linear regression relationship with MCs and WT. Changes in the functions of the gut microbiota may help
meet its immunity and energy needs during cyanobacterial bloom stress. These results provide key information for understanding the response pattern of freshwater snail intestinal flora to cyanobacterial blooms and reveal the underlying environmental adaptation mechanism of gastropods from the perspective of intestinal flora.
Given the scarcity of water and land resources, coupled with the competitive nature of aquaculture, the long-term viability of this industry will depend on strategies for vertical development. This ...involves enhancing production environments, increasing productivity, and advancing aquaculture technologies. The use of biofloc technology offers a potential solution to mitigate the adverse environmental impacts and the heavy reliance on fishmeal in the aquaculture sector. This method is designed to effectively assimilate inorganic nitrogen found in aquaculture wastewater, thereby enhancing water quality. Additionally, this process produces microbial protein, which can serve as a viable supplemental feed for aquatic animals. Furthermore, this technique has the potential to reduce the feed conversion ratio, thereby lowering overall production costs. This article provides an overview of the evolving field of biofloc system technology within aquaculture. In this study, we will examine the historical development and various types of biofloc systems, as well as the factors that influence their effectiveness. Finally, we will explore the economic potential of implementing biofloc systems in aquaculture.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Frequent outbreaks of harmful cyanobacterial blooms and the cyanotoxins they produce not only seriously jeopardize the health of freshwater ecosystems but also directly affect the survival of aquatic ...organisms. In this study, the dynamic characteristics and response patterns of transcriptomes and gut microbiomes in gastropod
were investigated to explore the underlying response mechanisms to toxic cyanobacterial exposure. The results showed that toxic cyanobacteria exposure induced overall hepatopancreatic transcriptome changes. A total of 2128 differentially expressed genes were identified at different exposure stages, which were mainly related to antioxidation, immunity, and metabolism of energy substances. In the early phase (the first 7 days of exposure), the immune system may notably be the primary means of resistance to toxin stress, and it performs apoptosis to kill damaged cells. In the later phase (the last 7 days of exposure), oxidative stress and the degradation activities of exogenous substances play a dominant role, and nutrient substance metabolism provides energy to the body throughout the process. Microbiomic analysis showed that toxic cyanobacteria increased the diversity of gut microbiota, enhanced interactions between gut microbiota, and altered microbiota function. In addition, the changes in gut microbiota were correlated with the expression levels of antioxidant-, immune-, metabolic-related differentially expressed genes. These results provide a comprehensive understanding of gastropods and intestinal microbiota response to toxic cyanobacterial stress.
Gut microbes play a critical role in helping hosts adapt to external environmental changes and are becoming an important phenotype for evaluating the response of aquatic animals to environmental ...stresses. However, few studies have reported the role that gut microbes play after the exposure of gastropods to bloom-forming cyanobacteria and toxins. In this study, we investigated the response pattern and potential role of intestinal flora in freshwater gastropod
when exposed to toxic and non-toxic strains of
, respectively. Results showed that the composition of the intestinal flora of the toxin-producing cyanobacteria group (T group) changed significantly over time. The concentration of microcystins (MCs) in hepatopancreas tissue decreased from 2.41 ± 0.12 on day 7 to 1.43 ± 0.10 μg·g
dry weight on day 14 in the T group. The abundance of cellulase-producing bacteria (
) was significantly higher in the non-toxic cyanobacteria group (NT group) than that in the T group on day 14, whereas the relative abundance of MC-degrading bacteria (
and
) was significantly higher in the T group than that in the NT group on day 14. In addition, the co-occurrence networks in the T group were more complex than that in the NT group at day 7 and day 14. Some genera identified as key nodes, such as
,
and
, showed different patterns of variation in the co-occurrence network. Network nodes clustered to
increased in the NT group from day 7 to day 14, whereas the interactions between
and
and other bacteria almost changed from positive correlations in the D7T group to negative correlations in the D14T group. These results suggested that these bacteria not only have the ability to improve host resistance to toxic cyanobacterial stress by themselves, but they can also further assist host adaptation to environmental stress by regulating the interaction patterns within the community. This study provides useful information for understanding the role of freshwater gastropod gut flora in response to toxic cyanobacteria and reveals the underlying tolerance mechanisms of
to toxic cyanobacteria.
Elucidating the bacterioplankton spatial distribution patterns and its determinants is a central topic in ecological research. However, research on the distribution patterns of bacterioplankton ...community composition (BCC) within a small-sized, highly dynamic freshwater lake remains unclear. In this study, we collected surface water samples from West Lake to investigate the spatiotemporal variation of BCC by 16S rRNA gene high-throughput sequencing. Clear spatial heterogeneity in BCC was identified both in summer and winter. The relatively high abundant taxa exhibited greater correlations with environmental factors and other abundant species in summer than in winter. Variation partitioning analysis was used to unravel the relative importance of environmental factors and spatial processes and further explore the underlying mechanism of BCC successions. Our results showed the predominant shared effect of environmental and spatial factors on BCC in summer (68.41%) and winter (57.37%), indicating that spatially structured environmental factors were the key determinants of structuring BCC spatial heterogeneity in West Lake in the two seasons. Furthermore, environmental factors alone explained a higher proportion of the variation in summer whereas spatial factors explained a higher proportion in winter. These divergences may be related to seasonal environmental changes and anthropogenic disturbances. Our study provided knowledge on BCC spatial heterogeneity in small freshwater habitats and their underlying determinants in different seasons.
The health conditions of fish habitats, which affect fish health, can be reflected by the structure and ecological function of the bacterioplankton community to some extent. However, studies on ...bacterioplankton in the whole habitat of migratory fish, which can be divided into different functional types, are still limited. To fill this gap, we investigated the characteristics of bacterioplankton communities in three habitat types in a typical migratory fish habitat, the southern East China Sea, using 16S rRNA gene amplicon sequencing. Our study showed that the structure of the bacterioplankton community was significantly divided according to habitat type. Dispersal limitation and heterogeneous selection both contributed to the bacterioplankton community assembly through estimation of β nearest taxon index (βNTI), and redundancy analysis (RDA) further explained that the water temperature, salinity, and nutrients were deterministic factors responsible for differences in the bacterioplankton community. Additionally, different ecological functional modules dominated by functional bacterioplankton in different habitat types were identified by co-occurrence network analysis, including a hydrocarbon-degrading module dominated by
Psychrobacter
and health-related modules containing
Ascidiaceihabitans
and
Pseudoalteromonas
. Based on the composition of environmental bacterioplankton, our findings provide a theoretical basis for understanding the distribution of different habitat types in the southern East China Sea during the breeding period of migratory fish.
In the modern era of Aquaculture, biofloc technology (BFT) systems have attained crucial attention. This technology is used to reduce water renewal with the removal of nitrogen and to provide ...additional feed. In BFT, microorganisms play a crucial role due to their complex metabolic properties. Pathogens can be controlled through multiple mechanisms using probiotics, which can promote host development and enhance the quality of the culture environment. During culturing in a biofloc technology system, the supplementation of microalgae and its accompanying bacteria plays a beneficial role in reducing nitrogenous compounds. This enhances water quality and creates favorable environmental conditions for specific bacterial groups, while simultaneously reducing the dependency on carbon sources with higher content. The fluctuations in the bacterial communities of the intestine are closely associated with the severity of diseases related to shrimp and are used to evaluate the health status of shrimp. Overall, we will review the microbes associated with shrimp culture in BFT and their effects on shrimp growth. We will also examine the microbial impacts on the growth performance of
in BFT, as well as the close relationship between probiotics and the intestinal microbes of
.
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