Decrease In Population Density Research Articles

Residue management and overwinter survival in winter canola (Brassica napus L.)

Winter canola production in eastern Canada is a growing segment of the Canadian canola industry. Crop establishment and survival overwinter have been identified as two of the major challenges associated with the production of winter canola. Environmental conditions can interact with agronomic practices, including seeding date, plant population density, fertility, and residue management, to influence stand establishment in autumn and overwinter survival. The objective of the current research was to evaluate the impact and interaction of preceding crop residue and tillage practices on the establishment, overwinter survival, and yield of winter canola in southern Ontario. Winter canola was seeded following either winter wheat or soybean and using conventional, no-till, or strip-till practices. Over the course of the 3 years of study, the annual decline in winter canola plant population density was influenced by the type of tillage practice used but not by the preceding crop. The overwinter decrease in plant population density was largest in no-till, followed by strip-till, and finally conventional tillage. At physiological maturity, winter canola yields in reduced tillage practices (i.e., no-till and strip-till) were equivalent to those achieved utilizing conventional tillage practices. When grain yields were standardized as a function of the spring plant population density, the highest and lowest yield per plant coincided with the lowest and highest plant population densities and were observed in strip-till (14.2 g plant−1) and no-till (9.1 g plant−1), respectively. Results of this research have established that winter canola can be successfully produced in Ontario utilizing a range of tillage practices.

Proximity to cancer rehabilitation and exercise oncology by geography, race, and socioeconomic status.

Cancer rehabilitation and exercise oncology (CR/EO) have documented benefits for people living with and beyond cancer. The authors examined proximity to CR/EO programs across the United States with respect to population density, race and ethnicity, socioeconomic status, and cancer incidence and mortality rates. This cross-sectional study was conducted in 2022-2023. Online searches were initiated to identify CR/EO programs. Geocoding was used to obtain latitudinal and longitudinal geospatial coordinates. Demographic data were abstracted from the 2020 5-year American Community Survey. Cancer incidence and mortality data were obtained from the Centers for Disease Control and Prevention. US 2013 Rural-Urban Continuum Code (RUCC) classification was used to define counties as either urban (RUCC 1-3) or rural (RUCC 4-9). Multivariable logistic regression was used to evaluate the association between being far from a program and census-tract level factors. In total, 2133 CR/EO programs were identified nationwide. The distance from a program increased with decreasing population density: rural tracts were 17.68±0.24 miles farther from a program compared with urban tracts (p<.001). Program proximity decreased as the neighborhood deprivation index increased (p<.001). Exercise oncology programs were less common than cancer rehabilitation programs in tracts with a larger proportion of minority residents (p<.001). Prior research has documented that underrepresented populations have worse cancer-related symptoms and higher cancer mortality. Herein, the authors document their findings that these same populations are less likely to have proximity to CR/EO programs, which are associated with improved cancer-related symptoms and cancer mortality outcomes. To realize the positive outcomes from CR/EO programming, efforts must focus on supporting expanded programming and sustainable payment for these services.

From consumption to context: assessing poverty and inequality across diverse socio-ecological systems in Ghana

Local social and ecological contexts influence the experience of poverty and inequality in a number of ways that include shaping livelihood opportunities and determining the available infrastructure, services and environmental resources, as well as people’s capacity to use them. The metrics used to define poverty and inequality function to guide local and international development policy but how these interact with the local ecological contexts is not well explored. We use a social-ecological systems (SES) lens to empirically examine how context relates to various measures of human well-being at a national scale in Ghana. Using a novel dataset constructed from the 100% Ghanian Census, we examine poverty and inequality at a fine population level across and within multiple dimensions of well-being. First, we describe how well-being varies within different Ghanian SES contexts. Second, we ask whether monetary consumption acts a good indicator for well-being across these contexts. Third, we examine measures of inequality in various metrics across SES types. We find consumption distributions differ across SES types and are markedly distinct from regional distributions based on political boundaries. Rates of improved well-being are positively correlated with consumption levels in all SES types, but correlations are weaker in less-developed contexts like, rangelands and wildlands. Finally, while consumption inequality is quite consistent across SES types, inequality in other measures of living standards (housing, water, sanitation, etc) increases dramatically in SES types as population density and infrastructural development decreases. We advocate that SES types should be recognized as distinct contexts in which actions to mitigate poverty and inequality should better incorporate the challenges unique to each.

Desertification in northern China from 2000 to 2020: The spatial–temporal processes and driving mechanisms

Desertification is one of the most significant environmental and social challenges globally. Monitoring desertification dynamics and quantitatively identifying the contributions of its driving factors are crucial for land restoration and sustainable development. This study develops a standardized methodological framework that combines desertification dynamics with driving mechanisms at the pixel level, applied to northern China from 2000 to 2020. Using multisource data and employing the Time Series Segmentation and Residual Trend analysis (TSS-RESTREND) method alongside geographical detector, we quantitatively assessed desertification reversion, expansion, and abrupt change processes, along with the impacts and interactions of natural and human factors were quantitatively assessed. Over the past two decades, the proportion of desertified land decreased by 5.60%. Notably, 32.88% of the study area experienced significant desertification reversion, while only 5.86% underwent expansion. Abrupt changes in both reversed and expanding areas were observed, primarily in the central and western regions, with these changes concentrated in the periods of 2009–2011 and 2014–2016. The impacts of various factors in different sub-regions exhibited significant spatial heterogeneity. Increased precipitation, temperature, and evapotranspiration contributed to reversion in the western area, while decreased wind speed influenced the eastern area. Additionally, decreased population density and afforestation activities also promoted desertification reversion. In contrast, decreased precipitation and increased temperature contributed to expansion in the western and eastern areas, respectively, with increased population density exacerbating this process. Overall, the interactions between natural and human factors were enhanced. Future desertification control and ecological engineering planning should focus on the coupling effects of different driving factors and relevant abrupt vegetation changes.

Predicting malaria hyper endemic zones in West Africa using a regional scale dynamical malaria model

Due to the continuing large number of malaria-related deaths in tropical Africa, the need to develop a robust Malaria Early Warning System (MEWS) for effective action is growing to guide cost-effective implementation of interventions. This study employs a two-stage hierarchical evaluation technique to evaluate the ability of the VECTRI malaria model to simulate malaria dynamics at seasonal time scale (1 - 7 months) over Nigeria and West Africa. Two sets of malaria simulations are considered. The first set is based on VECTRI simulations driven by observed rainfall and temperature datasets (hereafter referred to as control run). The second is based on malaria simulations driven by the European Centre for Medium-Range Weather Forecasting (ECMWF) System5 ensemble seasonal forecasting system (hereafter referred to as Forecast run). Different metrics are employed to assess the skill of the VECTRI malaria model. Results based on the control run indicate that the model can reproduce hyper-endemic zones and the evolution of malaria cases, particularly the observed increase in cases with decreasing population density. Despite having significant biases and low correlation, the model successfully predicts annual anomalies in malaria cases across Nigeria, particularly in the savannah region that experience large malaria burden. Annual correlations between the VECTRI Forecast run and the VECTRI Control run are relatively low at all lead times (LT) and for each start date (SD) across West Africa, although correlation generally increases from the Gulf of Guinea to the Sahel. Despite low correlations, the Rank Probability Skill Score (RPSS) reveals that the model has a statistically significant skill in predicting malaria occurrences across all categories of malaria cases, regardless of start date or lead time. While the Guinea Forest has the strongest RPSS, the increase or decrease in skill from the first to seventh lead time varies significantly across the region. In addition, the VECTRI malaria model has a good ability to discriminate variability in malaria cases across all regions, with an average Area Under the Relative Operating Characteristics (ROC) Curve (AUC) of approximately 0.62. Our findings suggest that the VECTRI malaria model could be used as a reliable Malaria Early Warning System (MEWS), particularly for identifying malaria hyper-endemic zones in West Africa at seasonal time scale.

Деякі регіональні особливості вимушеної міграції з України: столиця та інші регіони.

The forced migration of Ukrainians within the country and abroad has become a characteristic feature of the era of full-scale invasion. It saved the lives and health of many people, as a decrease in population density in the areas most affected by the hostilities leads to a decrease in human losses. Despite the great research interest in the topic of forced migration, some aspects of it still remain poorly understood, in particular, it is important to study the peculiarities of forced migration at the localities level, at least in large cities. The purpose of this article is to single out the category of forced migrants who lived in Kyiv before the full-scale invasion by the aggressor country and to identify the peculiarities of staying abroad and the attitudes of this group. To achieve this goal, general scientific methods of analysis, synthesis, and induction were used. Empirical data were collected using the method of sample surveys. The method of grouping was used to distinguish Kyiv residents from the general population of respondents, and the method of comparison was used to identify the peculiarities of their forced migration abroad. The study found that Kyiv residents are more likely to settle abroad in the capitals of their destination countries. Among them, there are more unmarried and childless individuals, which creates prerequisites for socio-economic integration outside the country. Also, people from the capital were less likely to have relatives abroad at the time of the full-scale invasion, which is likely due to their low level of participation in external labor migration in the previous period. Migrants from the capital proved to be better integrated in the countries of settlement, which is reflected in their proficiency in the local language, employment in the local labor market, and higher levels of financial well-being. At the same time, they retain stronger ties to Ukraine. Residents of Kyiv region are similar to Kyiv residents in some respects, while in others they are similar to residents of other regions. The study also revealed cases where the population of Kyiv region exhibited characteristics intermediate between Kyiv and other regions. The development of effective strategies for migration management, socio-economic development of the country during the war and post-war revival needs to take into account regional specifics.

Ecological restoration largely alleviates livestock grazing pressure in a montane grassland

Over the past few decades, grassland productivity in mountainous regions has been increasingly affected by livestock grazing and land use/cover changes. Human appropriation of net primary production (HANPP) is a valuable metric for assessing human impacts on grasslands. To date, knowledge of the patterns and drivers of HANPP in montane grasslands remains limited. In this study, we developed a 1 km × 1 km resolution HANPP dataset for the grasslands of the Qilian Mountains from 2000 to 2020 using two process-based models. We aimed to examine the spatial distribution characteristics and temporal trends of HANPP and explore the effects of climatic conditions, rural populations, cultivated areas, and livestock numbers on the interannual variability of HANPP. The results showed that HANPP decreased significantly with increasing elevation due to the corresponding decrease in population density. During the study period, HANPP showed a widespread decline, which was significant in 15.4% of the grassland area, mainly in alpine meadows. Climatic factors and human activities explained 60.8% and 39.2% of the temporal variability in HANPP, respectively. In particular, precipitation was negatively correlated with HANPP, whereas air temperature and number of livestock were positively correlated with HANPP based on correlation analysis. By providing a refined spatial assessment of human impacts on montane grasslands, this study suggests that ecological restoration projects, especially the Grain to Green and Grazing Withdrawal Programs, can reduce human pressures on grassland productivity by controlling population density and grazing intensity. Furthermore, the adoption of enclosed paddocks and supplemental feeding may mitigate montane grassland degradation near villages. This study elucidates the primary factors influencing the spatiotemporal patterns of HANPP in an area with typical montane grasslands, thereby supporting research-based decision making.

Investigating Endemic Species Conservation Hotspots Based on Species Distribution Models in Swat Region, Hindu Kush Pakistan

For the effective conservation of plant species, it is imperative to manage habitat loss and fragmentation by establishing a protected area network that comprehensively encompasses their habitat. In this study, we identified the suitable habitats for some endemic plant species in the Swat District, Pakistan, to conduct a thorough analysis of proposed protected areas (hotspot areas). Utilizing data from a recent botanical survey, environmental parameters from World-Clim, and various other sources, we determined the habitat of each species using the MaxEnt species distribution model. The modeled habitat suitability for each species were combined to generate maps illustrating endemic richness (hotspots), as well as to prioritize areas based on conservation value and habitat suitability. Future climate projections spanning from 2000 to 2050 were acquired from the WorldClim database Nineteen bioclimatic variables were assessed, incorporating data from three global climate models: CCSM4, HadGEM2-AO, and MPI-ESM-LR. We modeled seven endemic species from the Swat District and, by combining their maps, found three hotspot areas which show more environmental suitability under future climatic conditions. The future model forecasts a significant decrease in population density by the year 2050. Currently, these species exhibit their highest density along the eastern and southern borders of the valley, particularly in the Karakar, Elum border, Mankial Kalam, and Gabral Kalam areas. The anticipated alterations in density and distribution could have a considerable impact not only on the tree species but also on the associated sub flora.

Analysing district-level climate vulnerability pattern in Madhya Pradesh, India, based on agricultural and socio-economic indicators.

Indian agriculture transitioned from a food deficit sector to a food surplus following the Green Revolution. However, the continued progress of Indian agriculture has been hampered by climate change. This research explores the district-wise vulnerability in Madhya Pradesh, India, to climate change by assessing the composite vulnerability index using the agricultural vulnerability index (AVI) and socio-economic vulnerability index (SEVI). The study seeks to understand how agricultural and socio-economic factors lead to variations in vulnerability across districts and influence targeted adaptation and mitigation strategies. The trend analysis results present declining rainfall and inclining temperature from 1951 to 2021 in Madhya Pradesh, directly affecting the agricultural sector and human livelihood. The composite vulnerability index (CVI) results revealed that districts with low values (< 0.394), such as Burhanpur and Balaghat, demonstrate reduced susceptibility due to limited cultivation, low reliance on rainfall, lower drought susceptibility, and decreased population density. Districts such as Panna and Bhopal show moderate vulnerability (0.394-0.423), with lower fallow land, reduced rainfed agriculture, and socio-economic vulnerability. Extensive agriculture and marginalised workers' presence influence high vulnerability (0.423 to 0.456) in districts such as Tikamgarh and Indore. Districts like Barwani and Jhabua have the highest CVI values (> 0.456), indicating substantial susceptibility to climate impacts. The cluster analysis validates the results of the vulnerability index. The findings highlight the urgent need for tailored adaptation strategies to address the diverse agricultural and socio-economic indicators creating vulnerability in Madhya Pradesh. The study helps understand regional vulnerability patterns and provides evidence-based policy approaches for resilience to climate change effects.

Cooperation in public goods game does not require assortment and depends on population density.

The threshold public goods game is one of the best-known models of non-linear public goods dilemmas. Cooperators and defectors typically coexist in this game when the population is assumed to follow the so-called structured deme model. In this article, we develop a dynamical model of a general N-player game in which there is no deme structure: Individuals interact with randomly chosen neighbours and selection occurs between randomly chosen pairs of individuals. We show that in the deterministic limit, the dynamics in this model leads to the same replicator dynamics as in the structured deme model, i.e., coexistence of cooperators and defectors is typical in threshold public goods game even when the population is completely well mixed. We extend the model to study the effect of density dependence and density fluctuation on the dynamics. We show analytically and numerically that decreasing population density increases the equilibrium frequency of cooperators till the fixation of this strategy, but below a critical density cooperators abruptly disappear from the population. Our numerical investigations show that weak density fluctuations enhance cooperation, while strong fluctuations suppress it.

Effects of poor recruitment on riverine Smallmouth Bass population dynamics

AbstractObjectiveAltered flow regimes pose significant risks to the stability of populations of riverine Smallmouth Bass Micropterus dolomieu. Periods of poor recruitment, due to early life stage mortality resulting from high‐flow events, can cause size‐structure and density alterations of populations. The aim of this study was to opportunistically test for changes in dynamic rates of a riverine Smallmouth Bass population using a long‐term data set that spanned a period of poor recruitment.MethodsOur study evaluated size‐specific CPUE (fish/h), mortality, growth, and condition and tested for recruitment determinants of Smallmouth Bass through three consecutive years of poor age‐0 recruitment in the South Branch Potomac River, West Virginia. We used fall nighttime boat electrofishing surveys during 2009–2022 to monitor this population before and after the poor‐recruitment time frame (2016–2018).ResultAge‐0 CPUE was greater during the time frame prior to the poor‐recruitment time frame. However, there was no difference in the CPUE of quality‐length Smallmouth Bass between the two time frames and CPUE of preferred‐length fish was greater during the poor‐recruitment time frame. Growth and relative weight increased during the poor‐recruitment time frame. There was no significant difference detected in mortality between the recruitment time frames. Streamflow during the spawning period was a significant factor influencing fall recruitment of age‐0 Smallmouth Bass. A Ricker density‐dependent model with an added streamflow term performed as well as a basic, log‐linear streamflow model and a density‐independent model that also incorporated a streamflow term.ConclusionOur results provide evidence of density‐dependent structuring in this population. Decreases in population density increased population dynamic rates that maintained or improved size structure. High adult biomasses did not increase age‐0 recruitment. Many riverine Smallmouth Bass populations may display favorable density‐dependent responses to declines in juvenile recruitment. Thus, management agencies should better understand the resiliency of these populations prior to establishing expensive programs or regulations, which may be ineffective, to combat alterations in juvenile recruitment.

Impact of COVID-19 on foreign population resident in urban areas of Italy: selection of indicators, data sources, and definition of geographical stratification levels

to describe indicators, data sources, and levels of geographical stratification used within the framework of the CCM project "Epidemiological Surveillance and Control of COVID-19 in Metropolitan Urban Areas and for the containment of SARS-CoV-2 circulation in the immigrant population in Italy". population-based observational study based on data from the Integrated Covid-19 Surveillance System and the archive of hospital discharge records. interregional collaborative project. Resident population in 5 Italian Regions (Piedmont, Emilia-Romagna, Tuscany, Lazio, and Sicily). crude and age-standardized rates of diagnostic test utilization and positivity, hospitalization (in any department and in intensive care unit), and mortality in COVID-19 cases. starting from the set of 11 indicators from the Italian National Institute for Health, Migration and Poverty (INMP) project "Epidemiology of SARS-CoV-2 Infection (COVID-19) and Use of Health Services in the Immigrant Population and Vulnerable Population Groups in Italy", the five most effective indicators for CCM purposes were identified. The INMP project highlighted higher rates of test access and positivity among Italians compared to foreigners, higher standardized hospitalization rates among foreigners, and higher standardized mortality rates among Italians, with geographical and temporal heterogeneity. The intersection between the DEGURBA (degree of urbanisation) classification and altimetric zones defined five levels of territorial stratification characterized by decreasing population density. Approximately 81% of the population involved in the CCM project resided in the first two levels; 43% of Italians lived in areas with intermediate population density in hilly or plain areas, while 48% of foreigners were concentrated in densely populated areas. sharing the collaborative approach and a research methodology already tested, integrated with the analysis of disaggregated indicators by morphological, functional, and administrative characteristics of the residential territory, allowed for assessing differences in the impact of the pandemic between Italians and foreigners residing in more or less densely populated areas.

A review of heavy metal risks around e-waste sites and comparable municipal dumpsites in major African cities: Recommendations and future perspectives

In Africa, the effects of informal e-waste recycling on the environment are escalating. It is regularly transported from developed to developing nations, where it is disassembled informally in search of precious metals, thus increasing human exposure to harmful compounds. Africa has a serious problem with e-waste, as there are significant facilities in Ghana and Nigeria where imported e-waste is unsafely dismantled. however, because they are in high demand and less expensive than new ones, old electronic and electrical items are imported in large quantities, just like in many developing nations. After that, these objects are frequently scavenged to recover important metals through heating, burning, incubation in acids, and other techniques. Serious health hazards are associated with these activities for workers and individuals close to recycling plants. At e-waste sites in Africa, there have been documented instances of elevated concentrations of hazardous elements, persistent organic pollutants, and heavy metals in dust, soils, and vegetation, including plants consumed as food. Individuals who handle and dispose of e-waste are exposed to highly hazardous chemical substances. This paper examines heavy metal risks around e-waste sites and comparable municipal dumpsites in major African cities. Elevated concentrations of these heavy metals metal in downstream aquatic and marine habitats have resulted in additional environmental impacts. These effects have been associated with unfavourable outcomes in marine ecosystems, such as reduced fish stocks characterized by smaller sizes, increased susceptibility to illness, and decreased population densities. The evidence from the examined studies shows how much e-waste affects human health and the environment in Africa. Sub-Saharan African nations require a regulatory framework that includes specialized laws, facilities, and procedures for the safe recycling and disposal of e-waste.

Hospitalization and readmission after single-level fall: a population-based sample

BackgroundSingle-level falls (SLFs) in the older US population is a leading cause of hospital admission and rates are increasing. Unscheduled hospital readmission is regarded as a quality-of-care indication and a preventable burden on healthcare systems. We aimed to characterize the predictors of 30-day readmission following admission for SLF injuries among patients 65 years and older.MethodsWe conducted a retrospective cohort study using the Nationwide Readmission Database from 2018 to 2019. Included patients were 65 and older, admitted emergently following a SLF with a primary injury diagnosis. Hierarchical logit regression was used to model factors associated with readmission within 30 days of discharge.ResultsOf 1,338,905 trauma patients, 65 years or older, 61.3% had a single-level fall as the mechanism of injury. Among fallers, the average age was 81.1 years and 68.5% were female. SLF patients underwent more major therapeutic procedures (56.3% vs. 48.2%), spent over 2 million days in the hospital and incurred total charges of over $28 billion annually. Over 11% of SLF patients were readmitted within 30 days of discharge. Increasing income had a modest effect, where the highest zip code quartile was 9% less likely to be readmitted. Decreasing population density had a protective effect of readmission of 16%, comparing Non-Urban to Large Metropolitan. Transfer to short-term hospital, brain and vascular injuries were independent predictors of 30-day readmission in multivariable analysis (OR 2.50, 1.31, and 1.42, respectively). Palliative care consultation was protective (OR 0.41). The subsequent hospitalizations among those 30-day readmissions were primarily emergent (92.9%), consumed 260,876 hospital days and a total of $2.75 billion annually.ConclusionsSLFs exact costs to patients, health systems, and society. Transfer to short-term hospitals at discharge, along with brain and vascular injuries were strong predictors of 30-day readmission and warrant mitigation strategy development with consideration of expanded palliative care consultation.

Exploring the nexus of climate variability, population dynamics, and maize production in Togo: Implications for global warming and food security

Maize, which serves as the primary staple crop in Togo, plays a crucial role in supporting rural communities and ensuring food security. Comprehending the complex relationship between Togo's maize production, population dynamics, and climate variability is crucial for mitigating the impacts of global warming and guaranteeing long-term food security. The present study examines the climate patterns and their impact on maize cultivation in Togo for the period spanning from 1990 to 2020. During this temporal interval, significant variations were seen in important climate indices. The levels of rainfall and the frequency of wet days exhibited notable fluctuations, whereas the temperature and concentrations of air pollutants, specifically carbon dioxide (CO2) and nitrous oxide (N2O), had a persistent rising trajectory. The recorded temperature exhibited an increase from 27 ​°C in 1990 to 29 ​°C in 2020. The levels of CO2 emissions had a substantial increase from 1000 ​kt in 1990 to an estimated 2500 ​kt in 2020. Similarly, the emissions of N2O witnessed a notable rise of more than 800 ​kt over the same time frame. Using time series analysis, we examined the temporal characteristics and employed ARIMA predictive models to project maize production over the upcoming decade, considering the gradual decrease in rural population density. The studies highlight the significant implications of global warming on a worldwide scale, exerting a profound impact on the Earth. The agriculture sector, specifically maize production, had notable variations in yield and overall output. Notwithstanding the inherent fluctuations in output, maize continues to maintain its position as the most widely consumed and preferred crop in Togo, even in the face of the country's rapidly expanding population. As a result, Togo has increased its imports of maize to satisfy the growing demand. The present study sheds light on the intricate relationship between production parameters, including yield and quantity, and a range of environmental variables such as the frequency of precipitation, temperature, and levels of N2O, in addition to rural and urban population density. The statement underscores the pressing necessity to confront the issue of global warming and its subsequent impacts on agricultural methodologies. Furthermore, the results underscore the significance of considering population dynamics and climate variables in the prediction of forthcoming agricultural outcomes.

Enrofloxacin hydrochloride toxicological effects on crucian carp reflected by serological changes and neurotoxicity

Due to its water solubility and wide applicability, enrofloxacin hydrochloride (EH) may enter aquatic ecosystems and cause negative effects on aquatic organisms. This study aimed to explore toxicological effects via serological changes and neurotoxicity, which were induced by EH exposure in crucian carp (Carassius auratus var. Pengze). The drug residues in brain tissue and protein content in serum were determined to analyze serological changes. Alterations in brain tissue structure and function, cerebral microvessels permeability, and the expressions of gene and protein regarding blood-brain barrier (BBB) were studied to reflect the neurotoxicity. Employing a validated high-performance liquid chromatography (HPLC) method, EH residues could be detected at various time-points throughout the experiment. Enzyme-linked immunosorbent assay (ELISA) showed that EH increased the levels of S100B, NSE and GFAP proteins in serum. Additionally, there was a significant positive correlation between serum S100B, NSE protein contents and EH residues (P < 0.05). Hematoxylin and eosin (H&E) staining revealed brain damage from EH exposure by the formation of vacuoles in brain glial cells, pyknosis of the nucleus, and a decrease in cell population density. Transmission electron microscope (TEM) revealed morphological changes in microvessels and condensation of astrocyte nucleus. Evans blue (EB) permeability test visualized an obvious increase in cerebral microvessels leakage. The real-time quantitative PCR (qPCR) results indicated that EH up-regulated the mRNA expression levels of S100B, NSE and GFAP, down-regulated the mRNA expression levels of P-gp, ZO-1, Occludin and Claudin-5. The Western blot (WB) results demonstrated increased NSE and GFAP protein expressions, decreased P-gp and Occludin protein expressions following EH exposure in brain, in consistent with the gene expressions, respectively. In conclusion, these findings indicated that EH brought about marked rise in serum biomarker levels and disrupted the central nervous system (CNS) of crucian carp. These data would help elucidate the mechanism underlying EH-induced neurotoxicological effects.

Understanding the indirect impacts of urbanization on vegetation growth using the Continuum of Urbanity framework

Numerous studies investigated the direct impacts of urbanization on the loss and fragmentation of vegetated lands associated with urban expansion. Fewer studies, however, have examined the indirect impacts of urbanization on vegetation related to changes in livelihoods, lifestyles, and connectivity in non-urbanized areas, especially in the context of large-scale urban-rural migration. Here, we employ the Continuum of Urbanity framework to examine how changes in livelihoods, lifestyles, and connectivity in non-urbanized areas associated with urbanization affect vegetation, and thereby to understanding the indirect impacts of urbanization. We found there was a significant trend in human-induced EVI (HEVI) increase in non-urban areas, and such trend was coupled with decreased population density (PD) in forest land and grassland, but increased population density in cropland. The negative correlation between PD and HEVI became increasingly stronger from 2000 to 2011, but weakened since 2011. Livelihood income, lifestyles represented by consumption, and information connectivity to the outside world indirectly impacted HEVI by driving PD changes in non-urban areas. This indirect effect has shifted from positive to negative over the 20 years. These findings suggest that the indirect impacts of urbanization on vegetation growth are complicated and multifaceted, and understanding such impacts would be critically important to help turn urbanization into an opportunity for regional sustainable development.

Evaluating the cascade dam construction effects on endemic fish habitat and population status in spawning sites of Lancang River (in Tibet), China

Cascade dam constructions will alter the habitat of spawning sites and affect fish population in the Lancang River basin. This paper examines the impacts of cascade dam construction on four spawning sites, focusing on two co-distributed and endemic fish species: Schizothorax prenanti and Schizothorax davidi. An ecohydraulic modeling framework that combined hydro-morphodynamic, habitat, and population models was used to investigate changes in habitat quality and fish population under two scenarios: no-dam and with-dam. Fish habitat quality was evaluated using the habitat suitability index, and population fluctuations were assessed by the abundance and density of fish populations at all life stages. The simulation results indicated that cascade dam construction would fragment the spawning site habitat in the tailwater zone of the main stream and result in a decrease in fish population abundance and density. Conversely, spawning site habitats in backwater zone of tributaries would improve, and fish population abundance and density would increase. Additionally, the simulation results showed that the magnitude of fish population variations varied by species and life stages. These results highlight the different responses of spawning site location, fish species, and life stages to dam construction, which can help identify areas of the habitat with higher potential for finer-scale endemic fish conservation and recovery efforts. This study provides a comprehensive framework tool for fish ecological evaluation in dammed rivers, which has the potential to assist decision-makers involved in river ecosystem ecological conservation.

Study on Urban Expansion and Population Density Changes Based on the Inverse S-Shaped Function

For decades, the continuous advance of urbanization has led to the continuous expansion of urban land and rapid increase in the total area of cities. The phenomenon of urban land expansion faster than population growth has become widespread. High population density can lead to problems such as traffic congestion and exacerbated air pollution and can hinder sustainable development, affecting the quality of life of urban residents. China is currently in a phase of rapid urbanization, with high urban population density and rapid decline in urban population density. The decrease in urban population density is conducive to promoting sustainable urban development. This study selected 34 cities in China as sample cities and analyzed the spatial expansion and population density changes using land use and population density data from 2000, 2005, 2010, 2015, and 2020 in order to provide reference for controlling population density and promoting sustainable urban development. The conclusions of the study are as follows: In the 34 sample cities, the average urban radius was only 11.61 km in 2000, but reached 17.98 km in 2020, with an annual growth rate of 2.5%. There were significant spatial differences in urban expansion. Beijing and Shanghai, as the most developed cities in China, had urban radii exceeding 40 km, while the less developed cities of Liaoyang and Suzhou had urban radii of only 9 km. Although the population density decreased in most cities, the population density values in first-tier cities in China, such as Tianjin, Beijing, and Shanghai, continued to rise. Cities with loose spatial expansion patterns had faster decreases in population density than compact-type cities. The rate of urban spatial expansion was negatively correlated with changes in population density, with cities that had faster urban spatial expansion also having faster declines in artificial ground density.

Population Dynamics of Intertidal Resident Species during a Reduction in Asian Shore Crab Population

Hemigrapsus sanguineus (Asian shore crab), which is native to coastal estuarine habitats along the east coast of Asia, have overtaken a wide range of the coast in the northeastern region of the United States. Intertidal population densities of Hemigrapsus sanguineus, Cancer irroratus (Atlantic rock crab), Littorina littorea (Common periwinkle), and Modiolus demissus (Atlantic Ribbed Mussel), among others, were measured at three sample sites from 8/2/22 to 11/14/22 using quadrat sampling techniques. A period of removal was enacted solely upon Sample site #1 from 9/28/22 to 11/2/22 to cause a reduction in the Asian shore crab population. During the period of removal, no statistically significant changes in Asian shore crab demographics (Carapace size/sex ratios) would be observed (p = 0.181 for carapace size changes). There would however be an 8% decrease in Asian shore crab population density within Sample site #1, comparative to a 1% increase at Sample site 2. Rock crab population density at Sample site #1 would increase by a relatively drastic 31%, whereas the Rock crab population would experience only a 7% increase at Sample site #2. The Shannon-Weiner diversity index was used to derive the effective number of species (ENS). There would be a drastic difference in change of ENS following the removal period at Sample site #1 (increase of 0.248 ENS), and the change of ENS at Sample site #2 (decrease of 0.024 ENS), suggesting the reduction in Asian Shore Crab population played a role in increased population diversity of intertidal resident species.