Long-term Evolution Research Articles

Non-resonant relaxation of rotating globular clusters

The long-term relaxation of rotating, spherically symmetric globular clusters is investigated through an extension of the orbit-averaged Chandrasekhar non-resonant formalism. A comparison is made with the long-term evolution of the distribution function in action space, measured from averages of sets of $N$-body simulations up to core collapse. The impact of rotation on in-plane relaxation is found to be weak. In addition, we observe a clear match between theoretical predictions and $N$-body measurements. For the class of rotating models considered, we find no strong gravo-gyro catastrophe accelerating core collapse. Both kinetic theory and simulations predict a reshuffling of orbital inclinations from overpopulated regions to underpopulated ones. This trend accelerates as the amount of rotation is increased. Yet, for orbits closer to the rotational plane, the non-resonant prediction does not reproduce numerical measurements. We argue that this mismatch stems from these orbits' coherent interactions, which are not captured by the non-resonant formalism that only addresses local deflections.

Long-term evolution of Ti-Cu amorphous film: Agglomeration and crystallization behaviors of Cu

Sometimes the films deposited by magnetron sputtering are in a metastable state. The films tend to transition to the equilibrium phase, which is crucial for the stability of the microstructure and properties of the films in practical applications. In this study, Ti-Cu films were deposited using a high-power pulsed magnetron sputtering technique, and the evolution of the microstructure of the film under natural aging and thermal aging conditions was systematically investigated. The results showed that the as-deposited Ti-Cu film was amorphous, and as the aging time increased, particles comprising Cu agglomerates and crystalline phases were gradually formed in the film. During aging treatments, Cu agglomerates at the Ti-Cu film led to strong scattering and absorption of the incident light, resulting in reflectance losses. Cu agglomerates at the film was more intense under thermal aging conditions than under natural aging conditions, which was attributed to the fact that the provision of additional temperature could accelerate the diffusion of the smaller Cu atoms in the Ti-Cu amorphous film. Exploring the long-term evolution of the Ti-Cu film structure will provide theoretical guidance for the stability of films in practical applications.

High incidence of hepatocarcinoma in patients with advanced fibrosis treated with direct-acting antiviral agents for hepatitis C: A real-world retrospective study

BackgroundPatients treated with direct-acting antivirals for hepatitis C exhibit high cure rates and improved survival. However, there is limited knowledge on their long-term clinical evolution. AimsIn this study, we aimed to analyse the risk of hepatocarcinoma and hepatic decompensation in patients treated with direct-acting antivirals. MethodsWe conducted a retrospective single-centre study of Portuguese patients with advanced fibrosis treated with direct-acting antiviral agents between 2015 and 2022 at a tertiary hospital. ResultsOut of 460 patients, 50 (10.9 %) developed hepatocarcinoma and 36 (7.8 %) experienced hepatic decompensation. The risk for hepatocarcinoma was higher in patients aged over 55 (HR 4.87, 95 % CI 2.34–10.13, p < 0.001), with signs of portal hypertension (HR 3.83, 95 % CI 2.05–7.13, p < 0.001) and arterial hypertension (HR 1.98, 95 % CI 1.09–3.58, p = 0.024). Alcohol consumption (HR 3.30, 95 % CI 1.22–8.94, p = 0.019), signs of portal hypertension (HR 4.56, 95 % CI 2.19–9.48, p < 0.001) and hepatocarcinoma (HR 3.47, 95 % CI 1.69–7.10, p < 0.001) increased the risk of hepatic decompensation. ConclusionOur study found a high incidence of hepatocarcinoma and hepatic decompensation, along with high mortality, in patients with advanced fibrosis treated with direct-acting antivirals. We identified risk factors such as arterial hypertension, alcohol consumption, and signs of portal hypertension, highlighting their role in clinical management and patient monitoring.

Editorial preface to special issue: Cenozoic climate change in Asia in honour of Prof. Zhengtang Guo

The Asian monsoon has progressively become a megamonsoon system since the early Cenozoic. To improve our understanding of the complex nature of the Asian monsoon system, involving strong interactions between atmospheric, oceanic and terrestrial systems across different timescales, we present this special issue, entitled Cenozoic climate change in Asia. The special issue is dedicated to Prof. Zhengtang Guo in honour of his distinguished contributions as Editor-in-Chief of Global and Planetary Change to our understanding of the long-term evolution of the Asian monsoon system. The special issue consists of nineteen papers, grouped into three categories, that address Cenozoic climate change, mainly in Asia. The first category focuses on the plate tectonic-scale and considers how changes in palaeogeography and palaeotopography have shaped climate evolution. The second category addresses orbital- to suborbital-scale climate change and, in particular, explores the links between low-latitude insolation, high-latitude ice sheets and the Asian climate. The third category addresses millennial- to decadal-scale climate changes. In addition, past human-environment interactions are also discussed. These studies provide important insights into our understanding and prediction of both natural variability and human-induced climate changes in Asia and their linkages with global climate within the Earth System.

Coupling of porosity and diffusive transport in highly reactive systems: Open issues of reactive transport modelling

Mineral precipitation at interfaces between contrasting materials and porewaters decreases the local porosity and consequently reduces transport across the interface. The near-field of waste repositories usually contains reactive interfaces, and the long-term evolution of diffusive transport away from the waste across the near-field is of special interest in this context. Diffusion as well as further mineral reactions significantly slow down when complete porosity clogging is approached, such that any further development is difficult to detect in experiments. But ongoing diffusion, even if very limited, might be significant for relevant times of up to 1 million years. If clogging occurs in clay materials, experimental studies report a much stronger decrease in anion diffusion compared to that of cations or neutral species. Continuum-scale reactive transport codes can predict experimentally observed clogging, but rely on specific implementations based on conceptual assumptions. Typically, the codes calculate porewater-mineral reactions only within a single cell, and they neglect the physical contact of the clogging mineral in one cell with the porewater in an adjacent cell (no inter-cell reactions considered). This can lead to unrealistic model predictions if porosity approaches zero. For instance, neutral pH porewater is permitted to be in contact with clogging cement hydrates in the adjacent cell, and the implied dissolution of the high-pH minerals is not considered anymore. Thus, intrinsically reactive minerals can be converted erroneously into inert, relict phases by such models. We present a new approach that mimics inter-cell reactions. In doing so, clogging is substantially delayed, and no real steady state with the boundary conditions can be attained, in contrast to conventional approaches. Furthermore, we use a dual-porosity reactive transport approach that takes into account the electrostatic effects of charged clay surfaces on diffusion and precipitation, and apply it to concrete-clay interaction. No complete clogging of the pore space occurs, and the predictions well fit experimental data. Modelling studies that predict the separation of a reactive system into two domains by localised full porosity clogging, followed by separate internal equilibration of the domains, are widespread in the literature. This prediction is interpreted as a conceptual artefact of continuum-scale modelling, which should be avoided by allowing for reactions of completely clogged cells with adjacent porewater. For clays, the dual-porosity model may be a viable option in this respect.

Stability Studies of the Dilution Series of Different Antibiotic Stock Solutions in Culture Medium Incubated at 37 °C.

The long-term stability of antibiotics in culture media remains underexplored in scientific literature. This study evaluated the stability of eight distinct antibiotic stock solutions-amoxicillin, cefotaxime, neomycin, oxytetracycline, florfenicol, enrofloxacin, colistin, and potentiated sulfonamide-and their 10-fold dilution series in tryptone soy broth (TSB) at 37 °C, over 12 days. Samples were collected immediately after preparation and on days 1, 2, 5, 7, 9, and 12, with active substance concentrations measured using ultra-high-performance liquid chromatography (UHPLC) coupled with mass spectrometry. The results indicated that among the ultrapure water stock solutions, neomycin, florfenicol, and potentiated sulfonamide maintained stability (>95%). Within the culture medium, florfenicol showed consistent stability (100%) throughout the study, potentiated sulfonamide experienced minor degradation (>85%), and neomycin underwent significant degradation. Amoxicillin, oxytetracycline, and colistin displayed considerable degradation in both solution types but were more stable in ultrapure water solutions. The stability of cefotaxime and enrofloxacin in ultrapure water solutions and in the medium was very similar when compared; however, 3.6% of the former and 88.7% of the latter remained detectable by day 12. These findings are crucial for minimum inhibitory concentration (MIC) assessments, especially in minimum bactericidal concentration (MBC) studies, and in experiments concerning long-term evolution and co-selection. This study underscores the necessity of stability assessments in culture media to validate future experimental outcomes.

Endophytic Fungi in Rice Plants and Their Prospective Uses

In a long-term evolution, fungal endophytes have formed a mutually beneficial relationship with host plants. Therefore, what roles do fungal endophytes play in the growth and development of rice, one of the major food crops in the world, and agricultural production? This mini-review aims to highlight the diversity, identification, colonization, function, and mechanism of action of endophytic fungi isolated from rice tissues through a literature review; comprehensively expound the interaction mechanism between rice fungal endophytes and their hosts in stimulating the growth of rice plants and alleviating biological and abiotic stresses on plants; and contribute new ideas for rice production and a sustainable rice industry. Additionally, rice fungal endophytes, as a new resource, have broad prospects in the development of biopesticides, biocontrol agents, and new medicine.

Unraveling the control factors of long-term morphological evolution in the Yangtze Estuary: A synthesis of natural processes and human interventions

Quantitative research regarding the effects and contribution rates of both natural processes and human interventions on the long-term evolution of the Yangtze Estuary is currently insufficient. To address this, we employ the Mann-Kendall (M-K) test to analyze hydrological changes and utilize bathymetric maps from 1958 to 2019 to quantify erosion and deposition patterns. Subsequently, combined with the empirical orthogonal function (EOF) to separately identify the top three control factors and elucidate spatiotemporal characteristics of the main factors controlling the Yangtze Estuary's morphological evolution. The results showed that sediment load and runoff consistently rank within the top three with respective mean contribution rates of 40.5% and 19.4%. Sediment load prevails as the first control factor across all regions except for the North Passage, which experienced a transition from natural dominance to human domination in 1998. Notably, extremely events like the 1998 flood occupied more eigenweighting in the short term and progressed in ranking due to the strong channel-forming capacity. Regarding escalating human interventions, estuarine engineering projects affect estuarine shoals following initial deposition and subsequent erosion patterns. However, their influence tends to wane post-completion, often surpassed by natural processes. Specifically, since 2010, continuous navigation channel dredging has governed the morphological evolution of the North Passage. Additionally, sand mining targeting the Ruifeng Shoal has driven the post-evolution dynamics of the South Channel as the second control factor. Overall, this study enhances our understanding of the coupling driving mechanisms involving both natural processes and human interventions, thereby enabling improved strategies for future sustainable management in estuarine environments.

State of the engineered barrier system and host rock of the HE-E experiment after 12 years of heating

This paper presents the status of the HE-E heater experiment, which is currently running at the Mont Terri Underground Research Laboratory (URL) in Switzerland. The experiment is located in a 10 m-long section of a micro-tunnel in the shaly facies of the Opalinus Clay and includes two 4 m-long heater sections isolated by plugs. Heater 1 is located in a sand/bentonite (65/35) buffer section and Heater 2 is located in a granular bentonite buffer section. Heating started on 28 June 2011, and this paper reports results up to 30 June 2023. During the 12 years of heating the system has otherwise been left undisturbed, with ongoing but very slow resaturation from the Opalinus Clay. The observed response to heating is considered in two phases: (1) the initial transient period of about 500 days when heater temperatures rose to the target 140°C and (2) the subsequent evolution. Recently a novel telescoped drilling procedure has been performed to recover and characterize material from the bentonite buffer without interruption of the heating. This paper describes the experimental long-term evolution and status prior to this disturbance, together with expectations regarding the current state of the buffer.

Asymptotic dynamic graph order evolution analysis

In this work, we investigate the analysis of generators for dynamic graphs, which are defined as graphs whose topology changes over time. We focus on generated graphs whose order (number of nodes) varies over time. We use a concept called “sustainability” to qualify the long-term evolution of dynamic graphs. A dynamic graph is considered sustainable if its evolution does not result in a static, empty, or periodic graph. To illustrate how the analysis can be conducted, a parameterized and probability-based generator, named D3G3 (Degree-Driven Dynamic Geometric Graphs Generator), has been introduced in a recent work. From this model, we derive multiple scenarios that correspond to three trends in graph order evolution. Our central contribution lies in a mathematical framework that provides an expectation of the order of the graph at time step t+1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$t+1$$\\end{document}, given its order at time step t. Nevertheless, our analysis underscores the challenge of characterizing the sustainability of dynamic graphs, even when a formal mathematical model for graph order evolution is known.

New tetragonal phases of titanium under shock loading - Predicted by molecular dynamics and ab initio calculations

Based on molecular dynamics simulations of the long-term evolution of polycrystalline titanium structures under shock waves, a novel phase (ζ) has been identified to emerge at shock pressures of approximately 20 GPa. This phase originates from the initial HCP phase and the disordered structure induced by the shock. The energy change characteristics during this phase transition are explained based on the Helmholtz free energy under volume constraints. The ζ phase comprises framework atoms (F-atoms) with fixed positions and unfixed interstitial atoms (I-atoms), exhibiting incomplete symmetry. Validation of this phase structure using ab initio simulations and machine learning potentials supports its existence as a metastable structure. The transformation from the initial α phase to ζ phase is diffusional transformation, while the reverse transformation is multistage displacive transformation.

Observing changes in the present and paleo-glacial extents of major glaciers in the Alaknanda Basin of Central Himalaya

The erosional and depositional landforms modified by the glaciers can be used effectively to reconstruct the palaeo-glacial events along with dating techniques. In this study, a detailed reconstruction of the Satopanth Glacier (SPG), Bhagirath Kharak Glacier (BKG), and Bhagnyu Glacier (BG) in the Alaknanda Basin of Central Himalaya is carried out using glacier morphological features identified from a comprehensive dataset that includes historic toposheets (1882–1962), satellite images (1968–2020), and field observations (2019 & 2020). We also compute paleo, contemporary ice thickness, and glacier volumes using the Glacier Reconstructio (GlaRe) and the Himalayan Glacier Thickness Mapper (HIGTHIM) tools, respectively. Our results demonstrate that the region has witnessed three major glacial advances: Stage I (oldest), Stage II, and Stage III glaciations. The SPG, BKG, and BG were tributaries of a primary primitive glacier that existed during the Stage I glaciation that extended to the Mana village. The Stage I glacial moraines are at a distance of 8.4 ± 1.1 km, 7.8 ± 1 km, and 8.4 ± 1.1 km from the present-day snout of SPG, BKG, BG, while the Stage II moraines are 5.1 ± 0.71 km, 4.2 ± 0.58 km, and 5 ± 0.7 km away, and Stage III moraines are 1.9 ± 0.26 km, 1.3 ± 0.18 km, and 2.8 ± 0.39 km away, respectively. The area of the primitive glacier reduced (Stage I to the recent period) from 78 ± 4.6 km2 to 60 ± 3.6 km2 with a volume reduction from 4.7 ± 0.94 km3 to 3.5 ± 0.63 km3. Most importantly, the rate of recession of the glaciers in the Alaknanda Basin is more in the last 5 decades ∼(8.4 ± 1.1 m a−1 (SPG), 7.2 ± 1 m a−1 (BKG), 10 ± 1.4 m a−1 (BG)) than that reported over the last 12,000 years, which is ∼0.42 m a−1 (SPG), 0.35 m a−1 (BKG), 0.42 m a−1 (BG). The present study provides a detailed characterization of the long-term evolution of glaciers in the Alaknanda Basin for the first time.

Long-term evolution of Streptococcus mitis and Streptococcus pneumoniae leads to higher genetic diversity within rather than between human populations.

Evaluation of the apportionment of genetic diversity of human bacterial commensals within and between human populations is an important step in the characterization of their evolutionary potential. Recent studies showed a correlation between the genomic diversity of human commensal strains and that of their host, but the strength of this correlation and of the geographic structure among human populations is a matter of debate. Here, we studied the genomic diversity and evolution of the phylogenetically related oro-nasopharyngeal healthy-carriage Streptococcus mitis and Streptococcus pneumoniae, whose lifestyles range from stricter commensalism to high pathogenic potential. A total of 119 S. mitis genomes showed higher within- and among-host variation than 810 S. pneumoniae genomes in European, East Asian and African populations. Summary statistics of the site-frequency spectrum for synonymous and non-synonymous variation and ABC modelling showed this difference to be due to higher ancestral bacterial population effective size (Ne) in S. mitis, whose genomic variation has been maintained close to mutation-drift equilibrium across (at least many) generations, whereas S. pneumoniae has been expanding from a smaller ancestral bacterial population. Strikingly, both species show limited differentiation among human populations. As genetic differentiation is inversely proportional to the product of effective population size and migration rate (Nem), we argue that large Ne have led to similar differentiation patterns, even if m is very low for S. mitis. We conclude that more diversity within than among human populations and limited population differentiation must be common features of the human microbiome due to large Ne.

Low-luminosity accretion of Be/X-ray pulsar MAXI J1409−619

ABSTRACT This paper used Nuclear Spectroscopic Telescope Array observations to examine the temporal and spectral features of the Be/X-ray binary pulsar MAXI J1409−619. The timing analysis of the light curve finds the pulsation of the source at $(501.23\,\,\pm \,\,0.01)$ s. The pulse profile of the source in various energy bands was analysed and showed weak dependence on energy exhibiting asymmetric character and generally suggests a source accretion in the subcritical regime. The variation of pulse fraction with photon energy in general shows an increasing trend. Assuming a distance of 14.5 kpc, we calculated the 3–30 keV source luminosity to be $\sim 6.13\,\,\times \,\,10^{34}\,\,$ erg s$^{-1}$. The long-term spin evolution of the source was carried out, where the source underwent torque reversal.

Use of Viscous medium to study anthelmintic drug action in Caenorhabditis elegans

Caenorhabditis elegans is an appealing tool for experimental evolution and for working with antiparasitic drugs, from understanding the molecular mechanisms of drug action and resistance to uncover new drug targets. We present a new methodology for studying the impact of antiparasitic drugs in C. elegans. Viscous medium was initially designed for C. elegans maintenance during long-term evolution experiments. Viscous medium provides a less structured environment than the standard nematode growth media agar, yet the bacteria food source remains suspended. Further, the Viscous medium offers the worm population enough support to move freely, mate, and reproduce at a rate comparable to standard agar cultures. Here, the Viscous medium was adapted for use in antiparasitic research. We observed a similar sensitivity of C. elegans to anthelmintic drugs as in standard liquid media and statistical difference to the standard agar media through a larval development assay. Using Viscous medium in C. elegans studies will considerably improve antiparasitic resistance research, and this medium could be used in studies aimed at understanding long-term multigenerational drug activity.

Necessary to continue imaging spontaneous cervical artery dissecting pseudoaneurysms after one year?

Background and purposeThe value of long-term serial imaging of dissecting pseudoaneurysm (dPSA) is poorly characterized. This study investigated the long-term radiographic evolution of dPSA. MethodsWe performed a query in our institutional craniocervical artery dissection registry to identify cases with spontaneous dPSA who had at least one year of follow-up with serial angiographic imaging. We performed Wilcoxon rank-sum pairwise comparison test to determine if there was a significant change in the aneurysm size over time. ResultsThis observational cohort study included 76 patients (46 females; 64 dPSA in the internal carotid artery [ICA] and 12 in the vertebral artery [VA]) with a median age of 49.5 years (range 24-77). The initial median dPSA size was 8 mm (interquantile range(iqr) = 5.88-11mm), and the final median dPSA size was 7 mm (iqr = 4-11 mm). Most patients had either no change or reduction in dPSA size in the serial follow-up, with no significant change over time. All the patients had favorable outcomes at the last follow-up, and most patients were symptom-free from dPSA (92 %). Two patients (2.6%) experienced recurrent ischemic strokes in the same territory as the initial ischemic stroke without any change in dPSA size. ConclusionFurther serial scans for dPSA after one year may be deferred in the absence of interim clinical symptoms as most dPSA either remains stable or decreases in size. Recurrent stroke, although a rare event, was not associated with an increase in dPSA size.

Stochastic gravitational wave background: birth from string-wall death

We study a new source of stochastic gravitational wave background (SGWB) from the final collapse of a network of topological defects. Typically, the final collapse is considered negligible for generating gravitational waves (GWs) due to its subdominance compared with the network's long-term evolution in the scaling regime. However, in some cases, a network can be driven outside of horizon by inflation and later re-enter horizon. Then, the network's final collapse after re-entering horizon becomes the dominant GW source and therefore cannot be neglected. We demonstrate this phenomenon in the context of N DW = 1 string-wall networks which naturally arise in axion models, although the framework can be generalized to other types of topological networks. The final collapse of walls bounded by strings releases GWs. Our calculation of the corresponding GW spectrum suggests it could be related to the first few bins of the nano-Hertz SGWB signal possibly detected by various Pulsar Timing Array (PTA) collaborations. However, it is important to note that such GW spectrum falls within a relatively narrow frequency range, which may not completely account for the PTA signal that spans more than one order of magnitude in frequency. Furthermore, with different parameter choices, the resultant GWs generated in this mechanism could be probed by various GW interferometry experiments.

LSTEG: An evolutionary game model leveraging deep reinforcement learning for privacy behavior analysis on social networks

With the investment of third-party companies, various accurate recommendation services have emerged on social network platforms, making convenience and privacy concerns coexist for users. Platforms, users, and third-party companies have conflicts of interest around privacy issues, and privacy protection is not the only goal for them. For the analysis of multi-party behaviors related to privacy, a long short-term evolutionary game model (LSTEG) is proposed, where the long-term and short-term evolutionary processes describe the dynamics between three parties and between users, respectively. Their dynamic evolutionary processes are described by mean dynamic equations and all possible stationary-state conditions are analyzed theoretically. Deep reinforcement learning is adopted to solve these evolutionary stationary states and to reveal the rules of interdependence between long-term evolution and short-term evolution. Experiments conducted on real-world datasets show that this work can help platforms, users, and third-party companies to get a better sense of what is occurring in dynamic network environments.

The Peripheral Profile of the Chitinase 3-like-1 in Benign Multiple Sclerosis - A Single Centre's Experience.

A limited subgroup of multiple sclerosis (MS) patients present with a longterm disease evolution characterized by a limited disease progression, known as benign MS (BMS). Chitinase 3-like-1 (CHI3L1) levels are sensitive to inflammatory processes and may play a role in the pathogenesis of MS. In this observational, cross-sectional study, we aimed to evaluate the implications of serum CHI3L1 and inflammatory cytokines in BMS patients treated with interferon β-1b for over a decade. We collected serum samples from 17 BMS patients and 17 healthy controls (HC) to measure serum CHI3L1 levels and a Th17 panel of inflammatory cytokines. Serum levels of CHI3L1 were analysed using the sandwich ELISA method and the Th17 panel was assessed using the multiplex XMap technology on a Flexmap 3D Analyzer. Serum CHI3L1 levels did not differ significantly from HC. We identified a positive correlation between CHI3L1 levels and relapses during treatment. Our findings suggest that there are no differences in serum CHI3L1 levels between BMS patients and HC. However, serum CHI3L1 levels are sensitive to clinical inflammatory activity and may be associated with relapses in BMS patients.

Luminescence dating of glacially sourced deposits from northern Switzerland: Comparing multigrain aliquots and single grains of quartz and feldspar

A complex picture of the Pleistocene glaciation history of northern Switzerland has been identified over the last three decades. To gain further insights into the long-term landscape evolution, numerical dating is required. In the absence of alternative dating techniques, luminescence dating is the key method for establishing chronological constraints of past glaciations. However, this is presented with complex challenges, especially in regard to the resetting of the luminescence signal prior to deposition, the components contributing to the signal as well as the signal intensity and stability. In this study, the luminescence properties of glacially sourced deposits from northern Switzerland are assessed using single aliquot (SA) and single grain (SG) measurements of feldspar (F) and quartz (Q). While no obvious connection between bleaching and distal or proximal deposition in relation to the proposed ice margin is observed, most samples seem to reveal a partially bleached signature in F SG De measurements. This appears to be masked in the respective F SA measurements even though only few grains emit luminescence signals. In addition, comparisons between fading corrected infrared stimulated luminescence (IR) and post-infrared infrared stimulated luminescence (pIR) De values appear to be unreliable indicators of bleaching, even though these signals bleach at different rates. Hence, it is recommended to conduct both IR and pIR investigations in combination with Q measurements on a SG level. The dating potential of the investigated deposits remains rather limited, yet, in the sedimentologic context the presented results reveal that several glacial advances occurred prior to the Last Interglacial in the study area.