Continuous Trend Research Articles

Trends in continuity of treatment among children and adolescents living with HIV in 14 districts in South Africa from 2018-2023: A retrospective program analysis

ObjectivesUNAIDS estimates 152,984 children under 15 years living with HIV (C/ALHIV) by 2022 in South Africa. Monitoring the continuity of antiretroviral treatment remains challenging without electronic health records. We explored treatment cohort growth and interruption trends in 14-USAID-PEPFAR-supported districts. MethodsWe reviewed data from 2018 to 2023. We triangulated this data with NAOMI HIV estimates. We used Tableau version 2023.2 for analysis to understand heterogeneity in outcomes. ResultsHIV incidence halved from 4.3 per 1000 in 2017 to 2.5 per 1000 in 2022. HIV testing doubled: 188,371 in FY19Q1 to 399,708 in FY23Q4 while testing positivity declined from 3.3% to 0.7%. Linkage to treatment increased from 67% to 102%, viral suppression increased from 79% to 84%. C/ALHIV treatment cohort started at 82,897 in FY19Q1 and increased to 105,107 in FY20Q2. Subsequently, the cohort decreased to 79,288 in FY23Q4 despite 42,498 initiations and 62,256 returns. ConclusionsThe C/ALHIV treatment and viral suppression increased substantially commensurate with expected trends. Subsequent cohort decline was aligned to vertical transmission reduction, HIV incidence decline, and expected aging. We highlight the inadequacy of the information systems to quantify losses. We underscore a need for resources to enhance program monitoring and interventions to address this gap.

Spatial–temporal variations of sediment transport rate and driving factors in Shule River Basin, northwest China

The sediment content and transport rate of rivers are crucial indicators reflecting soil erosion, water quality, and water resource management in a region. Studying changes in river sediment transport rates within a basin is essential for evaluating water quality, restoring water ecosystems, and implementing soil and water conservation measures. This study focused on the Shule River Basin and utilized various methods such as moving average, cumulative anomaly, Mann–Kendall mutation test, Mann–Kendall (M–K) trend test, Sen’s slope estimation, Correlation analysis, wavelet analysis, R/S analysis, ARCGIS10.7 interpolation, non-uniformity coefficient, and concentration to analyze data from hydrologic stations at Changmapu (CMP), Panjiazhuang (PJZ), and Dangchengwan (DCW). The research examined the temporal and spatial characteristics of sediment transport rates and identified key driving factors. Findings revealed significant increases in annual sediment transport rates at CMP and PJZ by 12.227 and 4.318 kg/s (10a)−1, respectively, while DCW experienced a decrease of 0.677 kg/s (10a)−1. The sediment transport rate of the three stations had a sudden change around 1994. The average annual sediment transport rates displayed distinct cycles, with CMP, PJZ, and DCW showing cycles of 51a, 53a, and 29a respectively. Additionally, while CMP and PJZ exhibited a continuous upward trend in sediment transport rates, DCW showed a consistent decline. The annual average sediment transport rates of CMP, PJZ, and DCW were 1305.43 kg/s, 810.06 kg/s, and 247.80 kg/s, respectively. These research findings contribute to enhancing the comprehension of sediment dynamics in the arid region of northwest China and offer a theoretical basis for the restoration and management of ecological environments in similar areas in the future.

On the Search for Data-Driven and Reproducible Schizophrenia Subtypes Using Resting State fMRI Data From Multiple Sites.

For decades, fMRI data have been used to search for biomarkers for patients with schizophrenia. Still, firm conclusions are yet to be made, which is often attributed to the high internal heterogeneity of the disorder. A promising way to disentangle the heterogeneity is to search for subgroups of patients with more homogeneous biological profiles. We applied an unsupervised multiple co-clustering (MCC) method to identify subtypes using functional connectivity data from a multisite resting-state data set. We merged data from two publicly available databases and split the data into a discovery data set (143 patients and 143 healthy controls (HC)) and an external test data set (63 patients and 63HC) from independent sites. On the discovery data, we investigated the stability of the clustering toward data splits and initializations. Subsequently we searched for cluster solutions, also called "views," with a significant diagnosis association and evaluated these based on their subject and feature cluster separability, and correlation to clinical manifestations as measured with the positive and negative syndrome scale (PANSS). Finally, we validated our findings by testing the diagnosis association on the external test data. A major finding of our study was that the stability of the clustering was highly dependent on variations in the data set, and even across initializations, we found only a moderate subject clustering stability. Nevertheless, we still discovered one view with a significant diagnosis association. This view reproducibly showed an overrepresentation of schizophrenia patients in three subject clusters, and one feature cluster showed a continuous trend, ranging from positive to negative connectivity values, when sorted according to the proportions of patients with schizophrenia. When investigating all patients, none of the feature clusters in the view were associated with severity of positive, negative, and generalized symptoms, indicating that the cluster solutions reflect other disease related mechanisms.

Influence of cascade reservoirs on the distribution, transport, and retention patterns of biogenic elements in the Jinsha River

Cascade reservoirs construction can greatly alter flow regime and sediment transport of rivers, further affecting migration and transformation processes of biogenic elements. The Jinsha River (JSR) is the China's largest hydropower base and the main runoff, sediment suspension, and nutrient source areas of the Yangtze River. However, the distribution, transport, and retention patterns of biogenic elements in the JSR are still unclear under the influence of cascade reservoirs. Therefore, monthly concentration monitoring work was conducted from November 2021 to October 2023 for various forms of carbon (C), nitrogen (N), phosphorus (P), and silicon (Si). Results showed that the concentrations and fluxes of total phosphorus (TP) and particulate phosphorus (PP) exhibited continuous decreasing trends along the reservoirs cascade, whereas N exhibited contrasting trends. The concentrations of dissolved total carbon (DTC), dissolved inorganic carbon (DIC), and total silicon also showed decreasing trends from upstream to downstream, whereas their fluxes were primarily influenced by runoff and exhibited upward fluctuations. Compared with other biogenic elements, there was a more pronounced retention effect on TP and PP by reservoirs, with average retention rates of 8.29 % and 16.01 %, respectively. Longer hydraulic retention time (HRT) can retain more TP and PP. Meanwhile, the retention rates of DTC, DIC, and particulate silicon were positively correlated with HRT, while the retention rate of dissolved silicon (DSi) showed a positive correlation with reservoir age. Moreover, the higher ratios of dissolved inorganic nitrogen to dissolved inorganic phosphorus (DIP) and DSi to DIP have occurred, resulting in apparent P limitation, particularly during the non-flood season due to lower DIP concentration. Overall, cascade reservoirs construction exists great influences on the spatial allocation, fluxes transport, and biogeochemical cycles of biogenic elements, potentially affecting the stability of rivers ecosystem along the food chain network.

Thermo-mechanical processing characteristics and strain-rate-sensitive degradation properties of Mg-Er-Ni alloys

Hot deformation behavior, the corresponding microstructure evolution, and degradation properties of a weak-textured Mg-Er-Ni alloy containing a high-volume fraction of Ni-LPSO phases, have been investigated. Hot deformation behavior has been carried out in the temperatures range of 370 ∼ 460 °C and strain rates range of 0.001 ∼ 1 s−1. Flow stress-strain curves of high strain rate cases show a continuous increase trend without a steady or a peak stage, while that of low strain rate cases show an obvious dynamic softening after peak stress. Based on flow stress-strain curves, materials constants calculated by an Arrhenius-type constitutive equation, show a high n and Q compared to those of high-volume fraction α-Mg matrix Mg alloys. Optimal processing windows, based on the dynamic material model, is determined as high temperature domains. As for microstructure evolution, a complete recrystallization and dispersive Ni-LPSO fragments for high temperature & low strain rates while a restricted recrystallization and a streamline distribution LPSO phase for high temperature & high strain rates are observed. Varying degrees of continuous dynamic recrystallization, particle induced nucleation mechanism, as well as coordinated deformation of LPSO through kinking and bending account for the strain-rate-dependence hot deformation mechanism. As a result, dispersive Ni-LPSO fragments at low strain rates provide more degradation channels for the α-Mg matrix and thus possess better a degradation rate than the streamlined LPSO at high strain rates.

Peri-urban dynamics: assessing expansion patterns and influencing factors

BackgroundPeri-urbanization, the expansion of large metropolitan centers into adjacent peri-urban regions, is a growing concern due to land scarcity and escalating housing costs. These zones, a blend of rural and urban features, blur the line between urban and rural areas, creating new landscapes. This study examines historical, present, and potential growth trends in the peri-urban area surrounding Durgapur Municipal Corporation (DMC). Analytical techniques and spatial metrics are used to track development intensity changes over time, including built-up density, Shannon’s entropy, Landscape expansion index, Average Weighted Mean Expansion Index, Annual Built-Up Expansion Rate, Built-Up Expansion Intensity Index, and Built-Up Expansion Difference Index. Landscape indices like Patch Density, Edge Density, Landscape Shape Index, Largest Patch Index, Ratio of Open Space, and Area Weighted Mean Patch Fractal are used to understand fragmentation, connectivity, and spatial relationships. The Logistic Regression Model (LRM) is used to identify influencing factors and CA-Markov modeling for future built-up areas.ResultsBetween 1991 and 2001, built-up area in the region increased significantly, primarily due to urban development near industrial zones, roadways, and mining areas. The growth was primarily concentrated in the western sector and near National Highway-2 (NH-2). Urban sprawl was a continuous trend, with the highest built-up density in the South-South-East (SSE) direction from 1991 to 2011. Additionally, a key determinant of built-up development was the distance to the city core. By 2031, the built-up area is expected to concentrate in the western and southeast regions, reaching 177.90 km2.ConclusionsThis expansion is attributed to urban development near industrial zones, roadways, mining areas, and other infrastructure. The study identifies distance to the city center as a significant influencing factor for built-up development. The results emphasize the need for inclusive urban planning methods prioritizing sustainable development principles and prudent resource management for future growth and efficient management in the DMC’s peri-urban area.

One-Pot Synthesis of Color-Tunable Narrow-Bandwidth Ag-In-Ga-Zn-S Semiconductor Nanocrystals for Quantum-Dot Light-Emitting Diodes.

I-III-VI type semiconductor nanocrystals (NCs) have attracted considerable attention due to their environmental friendly nature and large-scale tunable emission. Herein, we report the successful synthesis of full-spectrum (470 to 614 nm) Ag-In-Ga-Zn-S (AIGZS) NCs by precisely regulating the In/Ga ratios using a facile one-pot method. Intriguingly, the photoluminescence (PL) peak width exhibits a continuous narrowing trend with extended reaction time, ultimately reaching a full width at half-maximum (fwhm) of 34 nm for green AIGZS NCs. Furthermore, the exciton relaxation dynamics of AIGZS NCs were systematically investigated using time-resolved photoluminescence and femtosecond transient absorption spectroscopy. Remarkably, we successfully fabricated blue, green, and red quantum-dot light-emitting diodes (QLEDs), forecasting the potential of AIGZS NCs with high color purity for applications in full-spectrum QLEDs.

High resolution Ordovician carbon isotope chemostratigraphy in South China and its significance for global correlation

Based on the Shidi-1 drill core, this paper presents new and highly time resolved carbon isotope data (δ13Ccarb) for the Early Ordovician through Early Silurian of the Yangtze Platform, South China. Five carbon isotopic shifts (C1-C5) through the late Tremadocian to the Katian have been recognized in the Shidi-1 drill core recordings. Together with previously published isotope data, a composite carbon isotope curve for the Yangtze platform, permits the identification of a continuous Ordovician carbon isotope trend with five prominent carbon isotope shifts; including the TSICE, the Late Tremadocian positive Isotopic Carbon Excursion (LTICE, named herein), the Late Floian Rise, the MDICE and the Pagoda Isotopic Carbon Excursion (PICE, named herein). The identification and documentation of these anomalies further strengthen the regional and global correlation of the Ordovician succession on the Yangtze platform. The long-term trend in carbon isotopes indicates that organic carbon burial increased gradually throughout the Great Biodiversification Event (GOBE). A tipping point is also marked by the Dapingian-Darriwilian border, which is followed by a notable shift in the environment and creatures in the middle Darriwilian.

Scenario Analysis of Food Phosphorus Footprint in Kisumu, a Lakeside East African City in Lake Victoria (Kenya).

Increased food production and consumption patterns have resulted in higher urban food phosphorus footprints, leading to a series of resource and environmental problems worldwide. We quantified the food phosphorus footprint of the African city of Kisumu using substance flow analysis. Our aim was to develop Kisumu's sustainable phosphorus management framework so that the city would reduce phosphorus losses into the food system. Our results show that in the year 2023, the import and export of food phosphorus in the Kisumu food system was 2730.26 ± 2.7% t P yr-1 and 3297.05 ± 2.4% t P yr-1, respectively. There was -566.79 ± -18% t P yr-1 food phosphorus deficit in the Kisumu food system. Crop planting subsystem runoff/leaching/erosion loss, household consumption subsystem waste loss, and pit latrine subsystem blackwater loss are the major pathways of phosphorus losses into the environment and the main contributors to the food phosphorus footprint in the city. The 2030 scenario analysis shows that implementing a comprehensive scenario scheme throughout the entire lifecycle process from phosphorus input to waste disposal is the best choice for reducing phosphorus losses and suppressing the growth of food phosphorus footprint in the future. Our study shows that the food phosphorus footprint in the Kisumu food system was 0.67 kg P cap-1yr-1 in 2023, which is still at a low level but may enter a continuous upward trend with the improvement of socio-economic development of the city. In our framework, we have proposed a few essential measures that include urine separation, installation of septic tank, adjustment of dietary structure, flexible layout of sanitary disposal facilities, and separation of organic waste streams to reduce food phosphorus footprints in Kisumu. Given the similarity of cities along the shores of Lake Victoria, our calculation methods and management strategies can be applied to other cities in the region.

Visceral fat mass dynamics in a 2-year randomized STrength versus ENdurance training trial in people with obesity.

To compare the effectiveness of strength versus endurance training on reducing visceral fat in individuals with obesity. For the STrength versus ENdurance (STEN) 24-month randomized clinical trial, we assigned 239 participants with abdominal obesity to either strength or endurance training (two to three times a week, 60 min/training session) in addition to standard nutritional counselling to promote a healthy diet. Changes in abdominal visceral adipose tissue (VAT) area quantified by magnetic resonance imaging after 12 months were defined as a primary endpoint. Participants (aged 44 years, 74% women, body mass index: 37 kg/m2, mean VAT volume: 4050 cm3) had an approximately 50% retention rate and a 30% good training programme adherence at 12 months. There was no difference between strength and endurance training in VAT volume dynamics after 12 and 24 months (p = .13). Only in the good adherence group did we find a trend for reduced VAT volume in both training regimens. Independently of the exercise programme, there was a continuous trend for moderate loss of abdominal subcutaneous AT volume, body fat mass, body mass index and improved parameters of insulin sensitivity. Although parameters of physical fitness improved upon both exercise interventions, the dynamics of resting energy expenditure, glucose and lipid metabolism parameters were not different between the intervention groups and did not significantly improve during the 2-year trial (p > .05). Despite heterogeneous individual training responses, strength and endurance training neither affected VAT volume nor key secondary endpoints differently.

Microstructure evolution and recrystallization mechanisms of a fine-grained nickel-based superalloy during thermal deformation process

The thermal deformation behavior of fine-grained GH93 alloy was investigated through isothermal compression tests at deformation temperatures of 930–1020 °C, strain rates of 0.001–1 s−1 and deformation amount of 50 %. Based on the true stress-strain data, the power dissipation maps, instability maps and hot processing maps of this alloy were established at different strains. The precision of the hot processing maps was verified by deformation microstructures, and the optimal processing parameter was ascertained to be 975–1010 °C/0.001–1 s−1. The microstructure evolution, dynamic recrystallization (DRX) and twinning evolution were analyzed by means of EBSD and SEM, simultaneously the DRX mechanisms under different deformation parameters were elucidated. The results demonstrate that the degree of recrystallization increases with the increase of deformation temperatures and the decrease of strain rates. At lower deformation temperatures, γ′ phases at grain boundaries hinder grain boundaries to slip and encourage dislocation entanglement, thereby promoting recrystallization. As the deformation temperatures increase, γ′ phases gradually dissolve, and the pinning effect weakens, leading to grain coarsening. The proportion of ∑3 twin boundaries shows a continuous upward trend with increasing temperature, which is consistent with the trend of changes in recrystallization volume fraction. DRX mechanisms of the alloy under different process parameters include continuous dynamic recrystallization (CDRX) mechanism and discontinuous dynamic recrystallization (DDRX) mechanism. DDRX is the main recrystallization mechanism, and CDRX mechanism becomes more active with increasing temperatures and decreasing strain rates, while it is still only an auxiliary nucleation mechanism.

Currency tail risk measurement and spillovers: An improved TENET approach

Based on an improved TENET approach, this paper analyses the tail risk of 32 major global currencies and measures the tail risk spillover among these currencies using daily data. We find that (i) The tail risk of USD, EUR, GBP and JPY is relatively high, while CNY shows low risk with a continuous upward trend; (ii) The total tail risk connectedness of currencies declines over time, but spikes during significant events in recent years; (iii) The tail risk spillover of currencies from developed economies is higher than developing economies. Moreover, European and North American currencies primarily exhibit tail risk spillover, while Asian and African (South African) currencies mainly absorb risk from other regions.

Quantitative identification on spatial mismatch characteristics between supply and demand of carbon sequestration services

Exploring the mismatch between supply and demand (SD) for carbon sequestration services (CSS) is essential for achieving the "double carbon" goal. However, more studies are needed on the traits of the spatial mismatch between SD in mountainous cities. We used the CASA model and the IPCC emission factor approach to address this issue and quantify the SD of CSS in Chongqing. Second, we established a matching relationship model for the SD of CSS in Chongqing. Finally, we applied the Structural Equation Model with the Partial Dependence Plots model to reveal the influencing factors and internal mechanisms of spatial mismatch between the SD of CSS in Chongqing. The outcomes confirmed a decrease in fashion in the total supply of CSS in Chongqing and growth in fashion in general demand from 2000 to 2020. The SD mismatch was mainly concentrated inside the central city and other built-up areas. The SD mismatch area had increased by 390%, indicating a continuous upward trend. In exploring the factors influencing the mismatch between the SD of CSS in Chongqing, supply is mainly positively influenced by NDVI, and demand and supply-demand relationships are influenced by population density and LUCC. We proposed policy suggestions to alleviate the spatial mismatch and practical significance for achieving the "double carbon" goal and promoting sustainable development.

Effect of internet of things on Oman road freight industry: the meditation of perceived utility

The expansion of the global supply chain has introduced a multitude of challenges, particularly in road freight transportation. These include extended lead times, high operational expenses, and limited end-to-end visibility. Modern technology must be included in the freight industry to streamline operations and maintain competitiveness. The freight transportation industry is poised for a shift driven by the Internet of Things. The Internet of Things delivers real-time tracking, predictive maintenance, and enhanced security which ushers in a new era for the road transportation industry. Adopting the internet of things will guarantee long-term competitive advantage and future success in a road freight sector. A skills gap remains an obstacle to the successful implementation of the Internet of Things. There has been limited research conducted on the effect of the Internet of Things in the Oman road freight industry. The goal of this study was to document the implementation of Internet of Things and its effect on operational effectiveness through perceived useful in Oman road freight industry. This study used a positivist research philosophy associated with quantitative research. Data was gathered from the five biggest companies in the road freight industry in Oman. A pilot test was conducted to assess the reliability of the research instrument used. A convenience sampling technique was administered to collect data from respondents. A total of 203 structured questions were distributed on-line to workers in road freight sector in Oman. A structural equation modelling was used to analyze the quantitative data in the study. Results show that the adoption of IoT in the road freight sector is a continuous trend. Further findings show that the relationship between IoT and operational effectiveness is partially mediated by perceived usefulness. Improved operational effectiveness is the primary impact of IoT on the road freight sector. Managers are informed that smart sensor technologies can be used with the IoT to allow asset visibility and save operational costs. Future research may explore the financial gains attained through the utilization of IoT within Oman road freight industry.

Synchronous Tropical Andean Hydroclimate Variability During the Last Millennium

AbstractThe impact of latitudinal variations in the Intertropical Convergence Zone (ITCZ) on northern Andean hydroclimate during the Medieval Climate Anomaly (MCA; 950–1,150 CE) and Little Ice Age (LIA; 1,300–1,850 CE) is uncertain. Synthesis of two new lacustrine paleoclimate records from the Eastern Colombian Andes with existing circum‐Andean records shows that effective moisture anomalies were synchronous and in phase across the tropical Andes during the last millennium. During the MCA, when the ITCZ was shifted northward, topographically controlled responses in the northern Andes to vigorous atmospheric convection resulted in low precipitation and high evaporation, while precipitation was also reduced in the southern tropical Andes. During the LIA, precipitation decreased in the northern Andes as the ITCZ migrated southward but was offset by cooling that lowered evaporation, establishing high effective moisture. In the southern tropical Andes, the southward ITCZ position simultaneously strengthened precipitation, increasing effective moisture. MCA‐like responses to continued warming trends could similarly reduce northern Andean precipitation while increasing evaporation, thereby lowering effective moisture and possibly reducing water resource availability.

Exploring the paths of energy conservation and emission reduction in aluminum industry in Henan province, China

As the world's largest producer and consumer of aluminum, China's aluminum industry is facing enormous pressure for energy conservation and emission reduction due to its traditional high energy consumption, high emissions, and high pollution. To explore the green and low-carbon development path of the aluminum industry, an integrated modelling framework was developed, including aluminum production forecasting and scrap recycling model, energy consumption-carbon emission-air pollutant emission model, and conservation supply curve method. Five different scenarios were set up to evaluate the energy saving and emission reduction potential of Henan Province from 2023 to 2050, by adopting four measures of accelerating the recycled aluminum, promoting energy efficiency technologies, expanding the scale of electrolytic cells, and increasing the share of renewable energy. The results showed that the production of alumina and primary aluminum decreased to 9.6 and 1.8 Mt respectively in 2050, while the future production of aluminum processing products and recycled aluminum showed a continuous upward trend. By 2050, production of recycled aluminum will increase to 14.0 Mt, expanding by about 5.7 times compared to 2022. The energy-saving and emission reduction potential of the integrated scenario is the most significant, with energy consumption, CO2, SO2, NOX, PM10, PM2.5 and fluoride decreased by 54.3, 73.0, 96.5, 72.7, 82.6, 82.6, and 98.9% compared to the business-as-usual scenario, respectively. The results also indicated that accelerating the recycled aluminum and optimizing energy structure are more effective for mitigation. Finally, policy suggestions for mitigating energy consumption and pollutant emissions of the aluminum industry in Henan Province were proposed. The systematic framework of this study can be widely applicable to other provinces and the whole country, which can provide some references for the aluminum industry to achieve the carbon peak and carbon neutrality targets.

Differences in the molecular organisation of tumours along the colon are linked to interactions within the tumour ecosystem

Tumours exhibit significant heterogeneity in their molecular profiles across patients, largely influenced by the tissue of origin, where certain driver gene mutations are predominantly associated with specific cancer types. Here, we unveil an additional layer of complexity: some cancer types display anatomic location-specific mutation profiles akin to tissue-specificity.To better understand this phenomenon, we concentrate on colon cancer. While prior studies have noted changes of the frequency of molecular alterations along the colon, the underlying reasons and whether those changes occur rather gradual or are distinct between the left and right colon, remain unclear. Developing and leveraging stringent statistical models on molecular data from 522 colorectal tumours from The Cancer Genome Atlas, we reveal disparities in molecular properties between the left and right colon affecting many genes. Interestingly, alterations in genes responsive to environmental cues and properties of the tumour ecosystem, including metabolites which we quantify in a cohort of 27 colorectal cancer patients, exhibit continuous trends along the colon.Employing network methodologies, we uncover close interactions between metabolites and genes, including drivers of colon cancer, showing continuous abundance or alteration profiles. This underscores how anatomic biases in the composition and interactions within the tumour ecosystem help explaining gradients of carcinogenesis along the colon.

Application of Improved Genetic Algorithm and Deep Learning in Cold Chain Logistics Distribution Demand Prediction

In order to solve the problem of inaccurate prediction results caused by the excessive impact of downstream on upstream suppliers in the process of cold chain logistics transportation demand prediction, the author proposes a demand prediction system Multi agent based on improved genetic algorithm and deep learning. The system will improve genetic algorithm, combine deep learning with practical problems in cold chain logistics supply chain, and evaluate the improved model through instance simulation. The results are as follows: After optimization, the order quantity of each stratum reduces the influence of retailers on upstream suppliers by more than 70%. As for the overall transportation cost, it shows a continuous upward trend within 20 cycles, while the total cost of each cycle fluctuates in a lower range after optimization, reducing the overall total cost by about 50%. It shows the reliability of the improved demand forecasting system in this study to greatly reduce storage and transportation costs.

Contemporary Trends in the Spatial Extent of Common Riverine Fish Species in Australia’s Murray–Darling Basin

As one of the world’s most regulated river basins, the semi-arid Murray–Darling Basin (MDB) in south-eastern Australia is considered at high ecological risk, with substantial declines in native fish populations already identified and climate change threats looming. This places great importance on the collection and use of data to document population trends over large spatial extents, inform management decisions, and provide baselines from which change can be measured. We used two medium-term data sets (10 MDB basin-wide fish surveys from 2004–2022) covering the 23 catchments and 68 sub-catchments of the MDB to investigate trends in the distribution of common riverine species at the entire basin scale. Fifteen native species were analysed for changes in their contemporary range, and whilst short-term changes were identified, all species showed no significant continuous trend over the study period. We further analysed the native species extent relative to their historic records, with bony herring and golden perch occurring in 78% and 68% of their historic river kilometres, respectively, whereas southern pygmy perch, northern river blackfish, silver perch, mountain galaxias, and freshwater catfish were all estimated to occur in less than 10% of their historic extent. Six established non-native species were also analysed and were very consistent in extent over the years, suggesting that they are near the available limits of expansion of their invasion. We provide effect sizes for the spatial extent index which can be used as baselines for future studies, especially those aiming to monitor changes in the spatial extent and population status of native species, or changes in the spatial extent of new or existing non-native species.

Exploring the Spatial and Temporal Trajectories of Land Use Carbon Emissions and Influencing Factors in the Aksu River Basin from 1990 to 2020

Land use changes lead to changes in the functions of different types of carbon sources and sinks, which are key sources of carbon emissions. The study of carbon emissions and its influencing factors in the Aksu River Basin from the perspective of land use change is of great importance for the promotion of integrated protection and restoration of mountains, water, forests, fields, lakes, grasslands, sand, and ice in the basin and to help achieve the goal of carbon peaking and carbon neutrality. Based on four periods of land use data and socio-economic data from 1990 to 2020, the total carbon emissions from land use were measured, and the spatial and temporal trajectories of carbon emissions and their influencing factors were explored. The results showed that:① from 1990 to 2020, arable land, forest land, construction land, and unused land showed a general increasing trend, whereas grasslands and water areas showed a decreasing trend. The spatial change in land use types was mainly characterized by the conversion of grasslands and unused land into arable land, and 83.58 % of the arable land conversion areas were concentrated in the southwest of Wensu, Aksu, and the northern part of Awat. ② The total net carbon emissions in the basin showed a continuous growth trend from 1990 to 2020, with a cumulative increase of 14.78×104 t. The increase in arable land was a key factor causing an increase in net carbon emissions in the basin. ③ The spatial distribution pattern of land use carbon emissions in the basin was high in the middle and low in the fourth, with significant changes in net carbon emissions mainly in the southern part of Wensu, Aksu, Awat, and Alaer. ④ Human activities had the strongest driving effect on land use carbon emissions, with their effects gradually increasing from east to west. The contribution of average annual temperature to land use carbon emissions was mainly concentrated in the eastern part of Aksu and the northern part of Awat, whereas average annual rainfall had a strong inhibitory effect on the northern part of Wensu and the western part of Aheqi.