Degree Of Fragmentation Research Articles

An Assessment of Ecological Sensitivity and Landscape Pattern in Abandoned Mining Land

In recent years, the development of abandoned mining land has become a focal point in landscape planning. However, during the development of abandoned mining land, there often exists a phenomenon of prioritizing economic considerations over ecological concerns, leading to a failure to achieve genuinely sustainable development. An ecological sensitivity assessment, guided by the principles of protection and development, provides an evaluation framework that directs planning strategies for abandoned mining land from the perspective of balanced development and conservation. To facilitate the development and construction of abandoned mining land, this paper utilizes GIS technology, on-site surveys, analytic hierarchy processes, etc. Taking the abandoned mining land in Haining, Zhejiang, China, as the research subject and considering its unique site conditions, ecological sensitivity is divided into topographic conditions, surface water systems, and plant landscapes. Ecological sensitivity factors are selected, and an ecological sensitivity assessment system is constructed from the perspectives of ecological conservation and sustainable development. Using ArcGIS 10.2 and Fragstats 4.2 software, landscape pattern analysis is conducted, exploring the relationship between landscape patterns and ecological sensitivity assessment results from the perspectives of landscape fragmentation, diversity, and aggregation. By comparing the results of single-factor sensitivity analysis and comprehensive sensitivity analysis, as well as landscape pattern indices before and after classifying ecologically sensitive areas, the practicality of the evaluation system is verified, facilitating planning studies and providing design recommendations for abandoned mining land. Landscape pattern indices serve as supplementary explanations for ecological sensitivity. Based on the results of ecological sensitivity assessment and landscape pattern indices, the ecological conservation levels in the research area are classified into five categories: the Level I Comprehensive Protection Zone, Level II Moderately Developed Zone, Level III Construction Suitable Zone, Level IV Core Construction Zone, and Level V Core Development Zone. These correspond to ecological protection zones, sightseeing experience zones, historical exhibition zones, core commercial zones, and themed amusement zones, respectively. The I-level sensitive area in the research area has the smallest range, while IV-level and VI-level sensitive areas have larger extents, exhibiting a high degree of overall landscape fragmentation but with diverse and dominant landscape types. Integrating ecological sensitivity assessment results and landscape pattern indices aids in delineating ecological conservation levels and regional functional recreation zones, guiding the rational recreation allocation of resources for abandoned mining land and promoting its development into a scenic area integrating ecology and tourism.

Thermal analysis and microstructure evolution of TiC/Ti6Al4V functionally graded material by direct energy deposition

Metal/ceramic functionally graded materials (FGMs) have attracted significant attention due to their ability to combine the unique mechanical properties of metals with the high-temperature resistance of ceramics while mitigating the thermal stresses arising from the differences in their thermal expansion coefficients. In this study, the directed energy deposition (DED) technology is applied to manufacturing TiC/Ti6Al4V FGMs with TiC contenting up to 50 wt%. However, the variations in composition gradients and the complex thermal cycling processes lead to difficulties in the microstructure evolution and control. Therefore, a combined approach involving finite element (FE) simulations and experiments was employed to investigate the mechanisms underlying microstructural transformations under various gradient thermal cycles. The results showed that the morphology of TiC in the FGM from top to bottom is as follows: coarse dendritic TiC + unmelted TiC, granular primary TiC + underdeveloped dendritic TiC, chain-like eutectic TiC + granular eutectic TiC. Meanwhile, both α-Ti and β-Ti exhibited equiaxed transformation, with their sizes decreasing continuously with the gradient. This is due to the strong orientation relationship between TiC particles and the titanium matrix, allowing α-Ti and β-Ti to form non-uniform nucleation within the TiC phase. In addition, the chain-like eutectic TiC and dendritic primary TiC showed a certain degree of fragmentation and granulation after undergoing thermal cycling. The microstructural evolution mechanism in different gradient regions during the DED process under the coupling effect of thermal cycling and ceramic composition was clarified by combining the FE simulation results. The specimen at the bottom of FGMs exhibits strong and ductile (tensile strength: 1296 MPa, elongation: 7.17 %), which are mainly attributed to the Hall Petch strength and solid solution strengthening. The brittle phase of dendritic TiC and unmelted TiC under high gradients leads to decreased tensile properties.

3D pore structure characterization and permeability anisotropy visualization simulation of fusain

The Jurassic‒Cretaceous coal seams in northern China are rich in fusains, and the pore size of the residual plant tissue in fusains is much larger than the limit value of seepage pores and even larger than that of some microfractures in coal. Therefore, understanding the 3D pore structure and permeability of fusains is helpful for determining the physical characteristics of inertinite-rich coal reservoirs. The porosity of the fusain varies widely, the pore structure has obvious directivity, and this study summarizes three pore types. Based on the visual distribution module of fluid migration, three types of seepage models of fusains were established, including the tubular cell structure seepage model, the broken cell wall pore seepage model, and the complete cell structure surface barrier seepage model. The results of the physical simulation verify the rationality of the three seepage models and show that the degree of fusification and cell pore fragmentation strongly affect the permeability of the fusain. For a low-rank coal reservoir with a rich fusain, the overall pore permeability is high, which is conducive to the seepage production of coalbed methane and is an important reference value for high-permeability layer selection.

The Influence of Tanning Chemical Agents on DNA Degradation: A Robust Procedure for the Analysis of Tanned Animal Hide-A Pilot Study.

Illegal wildlife trade is currently on the rise, and it is becoming one of the most lucrative crime sectors. The rarer the species, the higher the demand. Wildlife trade falls under international regulations, such as the CITES convention. Proving that this convention has been violated is a complex process and can be very difficult to do. DNA analysis methods remain (in many cases) the only way to determine whether a certain specimen originated from a protected animal species, a specific individual, or a species in which it is legal to trade. Tanned animal hides are a specific type of specimen. With this type of biological material, obtaining amplifiable DNA is often difficult. This pilot study aimed to map the effect of the chemicals used in the tanning process on the degradation of the DNA yielded from such samples. The DNA was quantified using two different approaches: qPCR and Qubit fluorometry. The degree of DNA fragmentation was assessed by determining the degradation index. The results indicate that reagents containing chromium have the greatest influence on DNA degradation. However, by using the presented protocol, enough amplifiable DNA can be obtained from hides treated with aluminum-based reagents.

Research on the bearing characteristics of brackets in thick hard roof mining sites and the effect of blasting on roof control

Deep mining stress increase and thick hard rock layer endowment drive rock body fissure expansion, leading to sudden fracture of the roof plate accidents. The roof slab of 11,129 working face in Zhangji Mine is a 16 m thick sandstone composite roof slab, whose compressive strength reaches 89.8 MPa. The hardness of the roof slab is high, its bearing capacity is high, and it is difficult to collapse. The hardness of the roof plate is high, its bearing capacity is high, and it is difficult to fall. If the roof plate does not fall in time, it will lead to the energy accumulation of itself, and the sudden fracture and fall will make the working face and the two roadways show the drastic mine pressure, which will lead to the risk of the coal wall appearing the slice of gangs, the roof falling and the pressure frame. Therefore, for the 11,129 working face thick hard sandstone roof plate direct cover and mining technology conditions. It is very necessary and imperative to research the artificial roof release technology of deep hole pre-cracking blasting to improve the adventitious fall of the thick hard roof plate, reduce the overhanging roof area of the mining hollow area, and reduce the incoming pressure strength of the roof plate. This paper adopts the research method combining theory, physical experiment, numerical simulation and field test, focusing on research and analysis of the deflection change of the roof plate after pre-cracking and blasting, the relationship between the roof plate and the role of the bracket, and the effect of artificial blasting to release the roof. The results show that the theoretical part deduces and analyzes the relationship equation of the influence of the rotating and sinking of the roof plate on the pressure of the support, and combined with the law of the roof plate-support action can be divided into three stages: (1) Initial stage of mining, (2) Rotating and sinking stage, and (3) Breakdown and fragmentation stage. The deep stress increase and the rock layer's own characteristics (hardness and thickness) are the main controlling factors to determine the bearing capacity of the stent. As the depth of coal mining increases, the pressure at the minimum roof control distance of the stent gradually increases from 11.5 to 34.6 MPa. The increase of rock hardness relatively reduces the force acting on the stent, and the stent bearing capacity decreases by 75% when the hardness increases from 8 to 32 GPa. The 11,129 engineering geological parameters are brought into the calculation to obtain the pressure in the stent control distance of 13.5–20.5 MPa. The simulation part analyzes the stress relief degree of the roof plate before and after the roof blasting, and the peak stress in front of the coal wall is reduced from 46.7 to 30.9 MPa, which is an obvious effect of pressure relief, and the simulation results are analyzed in comparison with the theoretical results to validate the reliability of the simulation results. Further, the physical similarity experiments were conducted to analyze the deformation behavior of mining instability and crack evolution characteristics of the overburden rock of the quarry after cutting the roof, and the peak stress of the coal wall was in the range of 22.7–27.8 MPa after the blasting decompression, which was mutually verified with the theoretical analysis and the simulation results to ensure the reliability of the calculation results. Combined with the geological conditions of the mine area, the "fan-shaped" blasting hole arrangement is proposed to carry out segmental blasting, and the specific parameters of different locations of the holes are given. The effect of pre-cracking blasting was examined, and it was found that the rock mass at the hole opening had a high degree of fragmentation, and the ring and strike cracks appeared alternately in the middle and lower part of the drilling holes, and the polygonal energy slit played a very effective role, and achieved the purpose of artificially releasing the roof. At the same time, it is improved the load-bearing environment of the mining support, which further improves the safety and efficiency production of the coal mine.

Research on shared parking allocation considering the heterogeneity of parking slot providers’ temporary parking demand

ABSTRACT Studies on the allocation of parking demand during the sharing period primarily focus on public parking users, ignoring parking slot providers’ temporary parking demand with heterogeneity. Therefore, this paper takes the allocation of parking slot providers’ temporary parking demand as the research object and establishes a differentiated parking allocation (DPA) model to maximize the platform’s net profit. The model is solved using the ant colony optimization (ACO) algorithm and compared with the First-Come-First-Served (FCFS) algorithm. Then, the platform adopts differentiated or undifferentiated charge measures when charging for the parking slot providers’ temporary parking demand. The numerical analysis is performed to select three indicators for evaluation: 1) the utilization rate, 2) the net profit, and 3) the degree of time fragmentation. Results show that the ACO algorithm has an excellent optimization effect in allocating, and the differentiated allocation-undifferentiated charges for the parking slot providers’ temporary parking demand is feasible.

Abstract A034: Development of a novel class of genomic biomarkers through mathematical modeling of cancer genome contiguity

Abstract Introduction: Chromosomal instability (CIN) is a hallmark of cancer aggressiveness. However, in lung adenocarcinoma (LUAD) the most common methods for measuring genomic instability, such as the weighted Genome Instability Index (wGII), are not reliable predictors of patient outcomes. The wGII measures the portion of the genome altered by copy number variation (CNV). The wGII quantifies aneuploidy but ignores other properties of CNVs such as their length distribution. We hypothesized that quantification of genome contiguity may overcome the limitations of wGII and help identify novel prognostic biomarkers. Method: We develop a novel measure of CIN based on mathematical modeling of genome breakage patterns. Utilizing segmented CNV profiles we infer two properties of the genome breakage process – its intensity and dispersion. Intensity is proportional to the number of genome breakpoints and is estimated by the total number of CNV segments. Dispersion quantifies spatial dependence of breakpoints over a wide range of genomic scales. It is computed by Ripley’s K-function which compares the distribution of breakpoints with a random Poisson point process. Jointly, intensity and dispersion, which we term the weighted Genome Contiguity Index (wGCI), estimate the contiguity of the genome. We contrast the wGCI with a heuristic score based on quantiles of segment lengths. Results: We sought to evaluate the association between the wGCI and patients’ survival in a proteogenomic cohort of 215 primary LUAD tumors profiled using whole-genome sequencing (WGS). In support of our hypothesis, we observed that patients had significantly better outcomes if their tumor genomes had longer segments compared to those with a high degree of fragmentation (P=0.014). Utilizing the wGCI, we found that tumor genomes with dispersed breakage (and low contiguity) were associated with worst outcomes (P=0.01). To identify mechanisms associated with dispersed breakage patterns we compared genomic features of the two groups. We found that LUAD tumors with highly fragmented genomes have a higher rate of TERT amplifications (P=0.005) and increased TERT RNA expression (P=2e-6). These tumors are also enriched for TP53 mutations (P=2e-16) and MYC amplifications (P=0.01). Given the cost and practical challenges of clinical WGS we leveraged mass-spectrometry proteomics to identify protein biomarkers. We found IGF2BP3 to be significantly upregulated (P=0.0006) in highly fragmented tumors and to be associated with worse outcomes (P=0.011). We use immunohistochemistry (IHC) to develop and validate IGF2BP3 as a prognostic biomarker in independent lung cancer cohorts. Conclusion: We introduced a novel quantitative measure of CIN that uniquely captures the impact of chromosome breakage on LUAD patients' clinical outcomes. Further, we identified upregulation of IGF2BP3 as a proxy to identify fragmented genomes using IHC. Our work underscores the value of mathematical modeling of genome breakage patterns to develop complex genomic biomarkers. Citation Format: Noshad Hosseini, Rahul Mannan, Alexey Nesvizhskii, Saravana Dhanasekaran, Marcin Cieslik. Development of a novel class of genomic biomarkers through mathematical modeling of cancer genome contiguity [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr A034.

Análisis del concepto de Competencia Digital Docente: una revisión sistemática de la literatura

The technological revolution experienced in today’s society has led educational organisations to assume the responsibility of training skills and abilities for this new context. Despite the high degree of complexity within technology-mediated ecosystems, the scientific literature seems to agree that the development of teachers' digital competence is identified to be a key variable of success. The definition of digital competence is however not clearly delineated. Moreover, direct and indirect interactions within this technology-mediated teaching and learning process are not clearly identified. The objective of this study is to define the concept of Digital Teaching Competence through a Systematic Literature Review published between 2017 and 2022, using the Scopus and Dialnet databases. A total of 316 references in English and Spanish were identified, of which 32 were selected for the final analysis, following the PRISMA protocol guidelines. The results confirm the existence of a high degree of conceptual fragmentation, as well as the lack of agreement on the terminology to be used. There is a need to reach a consensus on a taxonomy that facilitates, on one hand, the analysis of the elements that make up Digital Teaching Competence, and on the other hand, the improvement of the capacity to analyse specific contextual variables that contribute to enhancing technology-mediated teaching and learning processes.

Body size shift in sympatric insects in response to distinct selective forces in fragmented urban environments

AbstractPhenotypic plasticity, which encompasses the diversification of both irreversible and reversible traits, has long been considered an adaptive response by animals to varying environmental conditions. However, the process by which irreversible and reversible traits are coordinated to form an adaptive response to the changing environment has yet to be clarified. Here, we investigated the variation in body size of two urban insect species in the context of habitat fragmentation. These species were the Chinese cricket Gryllus chinensis and the stove grasshopper Diestrammena japonica, which are sympatric in urban housing estates. Results indicated that both species changed in body size in patches of urban environment. However, their body size shifts showed opposite tendencies and were influenced by distinct selective forces: Chinese crickets increased their body size with the patch history and predation risk, whereas stove grasshoppers decreased their body size with the degree of fragmentation of the patches. Territorial and competitive Chinese crickets rarely experience resource scarcity during urban environment fragmentation. Thus, a larger body size was preferred in response to intraspecific competition among Chinese crickets. By contrast, stove grasshoppers are group‐living and scramble for resources as competitors, requiring a large territory to secure adequate food for supporting a group of individuals. Consequently, stove grasshoppers frequently experienced resource scarcity in the patchy habitat, favoring small body size to reduce individual requirements throughout the life cycle. Our findings indicate that the body size shift of sympatric insects may be subjected to distinct selective forces in fragmented habitats, depending primarily on their reversible traits.

Numerical simulation of landscape ecological river flow structure based on vegetation patch distribution and fragmentation.

The self-organizing biological characteristics of vegetation and human activities lead to the disruption of the continuous spatial attributes of natural watersheds, which are significant factors affecting river wetland ecosystems. To clarify the landscape ecological flow characteristics of vegetation patch distribution and fragmentation, this study used the three-dimensional Reynolds stress turbulence model in ANSYS Fluent software. The model considered three vegetation patch coverages under two different submersion states and four fragmentation types of vegetation patches under the same coverage conditions within specific vegetation areas. The flow characteristics of longitudinally discontinuous rigid vegetation patches, occupying half of the width of the river channel, were numerically simulated. The model's applicability was verified by indoor open-channel flume experiments. The results indicated that: (1) The streamwise velocity in vegetated areas is significantly lower than in non-vegetated areas, and the difference in flow capacity between vegetated and non-vegetated areas increases with patch coverage and fragmentation degree. (2) In the non-submerged state, the maximum Reynolds stress in the vegetated area is located at the bottom of the vegetation and is negatively correlated with patch coverage but positively correlated with fragmentation degree. In the submerged state, the maximum Reynolds stress is located near the top of the canopy and is positively correlated with both patch coverage and fragmentation degree. (3) The longitudinal turbulent kinetic energy in the vegetated area is significantly higher than in the non-vegetated area. In the non-submerged state, the turbulent kinetic energy in the vegetated area is negatively correlated with patch coverage but positively correlated with fragmentation degree. In the submerged state, the turbulent kinetic energy of the longitudinal distribution in the free layer of the vegetated area is positively correlated with patch coverage, negatively correlated with fragmentation degree, and is only reflected in the upstream vegetation area.

РЕВАЛОРИЗАЦИЯ КУЛЬТУРНОГО НАСЛЕДИЯ В СРЕДЕ БЫТОВАНИЯ ЭТНОСА: НА ПРИМЕРЕ ДЕВИЧЬЕГО НАКОСНИКА ТЕЛЕУТОВ

The appeal to the theme of hair decorations of one of the small peoples of Siberia – the Teleuts is relevant for several reasons. Firstly, both literary sources and materials from museum collections are distinguished by a certain degree of fragmentation. Secondly, in modern conditions, there is a need to reconstruct this unique object of ethnocultural heritage, lost in the environment of veryday life. This is confirmed by the results of the expedition to the Bachata Teleuts in August 2023 with the participation of the author of the article. Therefore, there is a need for an integrated pproach to the study of this phenomenon in the culture of an ethnic group. The purpose of the study was to determine the possibilities of returning the heritage object to its value lost under the influence of time. Among the tasks aimed at achieving the goal was an appeal to the intangible ethnic heritage – the analysis of technologies for making girlish decorations for braids and related semantics reflecting the mythological ideas of the people.

Energy Dissipation and Fractal Properties of Coal under Cyclic Impact Loading

To investigate the periodic disturbance and damage characteristics of coal under different impact pressures, the stress‒strain failure and damage trends of weak, impact‐prone coal samples were analysed under different impact pressures and different numbers of impacts. Split‐Hopkinson pressure bar (SHPB) tests were conducted to study the stress‒strain curve, dynamic compressive strength, elastic modulus, failure strain, and absorbed energy responses with different numbers of impacts and different strain rates. Fractal theory and methods were applied to analyse the influence of different impact pressures and different numbers of impacts on coal sample failure to reveal the relationship between the number of impacts and the fractal size characteristics of coal fragmentation. The energy modes and failure modes of coal samples under different impact effects were analysed under dynamic loading. Regarding the energy absorption corresponding to different numbers of impacts, the energy absorption per unit volume (EAPUV) of three impacts was calculated to be 0.46 J/cm3. The number of impacts was directly correlated with the energy absorbed by the coal sample. Furthermore, the number of impacts was directly correlated with the severity of the deformation and damage of the coal sample and was inversely correlated with the fragmentation of the coal sample. The degree of coal sample fragmentation was directly proportional to the number of impacts, and the fractal dimension increased with the number of impacts. The study of the failure and fractal characteristics of coal samples under different impact pressures and different numbers of impacts provides important information for the prevention and control of coal mine rock bursts.

Cavity flow characteristics of a curved hull section impacting a free surface with inclined postures

The water entry of structures is a complex gas–liquid flow. This paper studies the asymmetrical flow characteristics of a curved hull section entering water through numerical and experimental methods. The free-falling test from drop heights of 250–900 mm and inclination angles from 0° to 20° is carried out. Compared to a smooth hull section (cutting the bottom appendage), the experimental results observe some special asymmetrical flow phenomena (i.e., flow separation, jet impact, bubble flows, and bubble expansion). The physical mechanisms behind these flows are explained through combing the free surface flow and pressure distribution obtained by the numerical method. The effects of the inclination angle and impact velocities on these flow phenomena are further discussed, and they increase the degree of flow separation, bubble volume, and fragmentation. The load characteristics before and after cavity formation are analyzed based on a volume-of-fluid method. The high pressure caused by bubble closure can produce an instantaneous impulse pressure that even be 34% larger than the conventional impact pressure and is worth noting. This study clarifies some complex asymmetrical impact flow characteristics of curved hull sections and thus reveals the evolution mechanism of gas–liquid flows for complex geometries during oblique water entry.

Research on the Protection and Dissemination of Cultural Heritage in Rural Landscapes Based on Image Processing

Abstract The countryside is an important part of the social development process, but with the acceleration of urbanization, the protection of rural landscapes as cultural heritage is facing an increasingly severe situation. In this study, image radiation correction, image fusion, cropping and mosaicing, geometric correction, band selection, and image enhancement are applied to rural landscapes using remote sensing image processing technology. A digital protection system for rural landscape cultural heritage is created using the processed rural landscapes. By comparing the accuracy of this paper’s method to other classification methods, we can explore the classification performance of this paper’s PCA method. By comparing the changes in rural landscape types before and after landscape protection, the effect of landscape protection is explored. Finally, the communication effect of rural landscapes on social media is explored by utilizing the evaluation index system. The PCA method employed in this paper achieves a landscape classification accuracy of 83%, which is significantly superior to the IHS transformation method (73.5%) and the Brovey transformation method (76%). After the rural landscape protection, the degree of landscape fragmentation in Village A was significantly improved compared to before the protection, and the effect of protection was remarkable. The scores of social media users on each dimension of the rural landscape communication effect in Village A were greater than 4, and rural landscape communication achieved a positive effect.

Structure, diversity, and genetic delimitation of two Magnolia species endemic to eastern Mexico

Abstract In Mexico, Magnolia species of the section Macrophylla have been segregated based on phenotypic characteristics. However, the wide environmental variation throughout their distribution area in the eastern region of the country could be the main cause of the high degree of morphological variation among the taxa of this section. Therefore, it is necessary to carry out studies at the genetic level to confirm the taxonomic identity of these species. In the present study, the diversity and genetic structure of the populations of Magnolia rzedowskiana and M. zotictla were estimated using simple sequence repeat markers. We evaluated whether the taxonomic delimitation as independent species is consistent with their degree of genetic differentiation, comparing three regions of chloroplast DNA: trnH-psbA, ORF350, and rpl32-trnL. The DNA was obtained from four populations of the two species, which are distributed in the states of Hidalgo, Querétaro and San Luis Potosí. The populations presented intermediate–high genetic diversity (He = 0.52–0.60), limited gene flow (Nm = 0.62) and high genetic differentiation (Fst = 0.288), which may be related to their low density and strong geographic isolation, caused by the high degree of fragmentation of their habitat. The phylogenetic analysis and the genetic differentiation values indicate that each of the populations of the two Magnolia species analyzed behaves as an independent evolutionary unit, so the taxonomic delimitation of the three M. rzedowskiana populations must be reconsidered. The results obtained could be very useful for implementing management and conservation strategies for these populations in the short term.

Tetrapod biodiversity in sambaquis from southern Brazil.

Fishermen-hunter-gatherers of sambaquis (Brazilian shell mounds) had an intimate affinity with marine-coastal environments, where they exploited a great variety of fish and mollusks that comprise the best documented fauna from sambaquis. However, other groups of animals as mammals, birds, reptiles, and amphibians are also present in these sites, but are relatively less studied. This paper is the first one focused exclusively on the Tetrapoda biodiversity of sambaquis and aimed to identify tetrapods of ten sites from southern Brazil. We present a faunal inventory and data regarding animal capture and environmental exploitation. We identified the specimens anatomically and taxonomically, analyzed them concerning fragmentation, and quantified the data for the number of identified specimens (NISP) and minimum number of individuals (MNI). Despite the high degree of fragmentation of remains, we identified 46 taxa. As expected, most were from marine animals: cetaceans (total NISP = 2,568 and MNI = 27), otariids (total NISP = 248 and MNI = 32), and seabirds (total NISP = 65 and MNI = 23), indicating great relevance of marine tetrapod fauna as a resource for sambaqui builders (79.39% of NISP). We thus document the close bond between fishermen-hunter-gatherers of sambaquis and the marine tetrapods in southern Brazil.

Simulation Analysis of the Influence of Amplitude on Deformation and Fracture Characteristics of Hard Rock under Ultrasonic Vibration Load

The utilization of auxiliary tools employing ultrasonic high-frequency vibration to enhance rock breaking efficiency holds significant potential for application in underground hard rock excavation engineering. To investigate the failure mechanism of rocks under high frequency ultrasonic vibration load, this study employs particle flow software PFC2D for numerical simulation. By incorporating boundary conditions from actual ultrasonic vibration rock breaking experiments and utilizing a parallel bond model to construct the rock, we analyze the deformation, damage, fracture, and energy evolution process of hard rocks subjected to vibrational loads. The results demonstrate that the maximum displacement in hard rocks increases nearly linearly with vibrations until reaching 5.0199 × 10−3 m, after which it plateaus. Additionally, macroscopic fissures formed during rock failure exhibit an X-shaped pattern. Furthermore, based on our model, we examine the impact of amplitude variation on hard rocks with an equal number of cycles (5,000,000 cycles). Under ultrasonic vibration loads, amplitude influences the total input energy within the rock system. While increasing amplitude does not alter maximum deformation in rocks, it enhances fragmentation degree, fracture degree and energy dissipation coefficient—thereby improving rock breaking efficiency.

Proportional representation and party fragmentation in electoral autocracies

ABSTRACT What is the relationship between the type of electoral system and the degree of party fragmentation in electoral autocracies? According to Duverger’s hypothesis, proportional representation (PR) is positively associated with party fragmentation. This study investigates whether this hypothesis holds true in non-democratic political systems that hold elections. I propose that, unlike in democracies, PR is negatively correlated with the level of party fragmentation in electoral autocracies. To test this hypothesis, I utilize panel data encompassing 37 non-democratic nations that held elections from 1975 to 2010. The results demonstrate that PR is inversely linked to both the number and size of political parties. The effective number of parties (ENP) is employed as a measure of party fragmentation, estimating the weighted size and quantity of political parties.

Ignition and energy release characteristics of energetic high-entropy alloy HfZrTiTa0.2Al0.8 under dynamic loading

Steel-like density HfZrTiTa0.2Al0.8 high entropy alloy (HEA) with a density of 7.78 g/cm3 is designed and fabricated as a novel energetic structural material (ESM). The microstructure, thermal analysis, compressive mechanical properties, ignition and energy release under dynamic loading are systemically investigated. The experimental results show that the HfZrTiTa0.2Al0.8 HEA has a single BCC solid solution structure, and spinodal decomposition with elements segregation in the nanoscale is observed. Thermal analysis shows the HEA keeps stable in the Ar atmosphere and the oxidizing reaction occurs in the Air atmosphere. The mechanical properties show brittle characteristics with maximum strength with 1520 MPa and fracture strain 0.07 and strain rate effect from 0.001s−1 to 3000s−1 is observed. Under high strain rate loading, the fracture-induced spark is observed, which is caused by an oxidizing reaction due to the rise. By direct ballistic test, the energy release velocity threshold is measured as 980 m/s, and the energy release intensity is more violent in higher velocity impact conditions. Moreover, the impact reaction degree is increased with increasing fragmentation degree and adiabatic temperature rise induced by impact. The designed HEA-ESM is a promising candidate that simultaneously possesses both high strength, high reactive heat and excellent energetic characteristics in the application field of high-strength ESM fragment.

Labor transfer, market development, and the outsourcing of forestry production by farmers: a case study in Fujian, China

IntroductionThe outsourcing of forestry production is an important form in the development of forestry specialization and is the compromise result of economic incentives, factor optimization and risk diversification for farmers. It can facilitate the collaboration between internal and external resources to improve the efficiency of resource allocation and promote the combination of small farmers and the high-quality development of modern forestry.Theory and methodsIn this research, we have analyzed the extrusion effect, the substitution effect, and the income effect of labor transfer on the outsourcing of forestry production by farmers based on the theory of farmers’ behavior. In addition, we have constructed an influence mechanism for the development of the outsourcing services market according to the theory of division of labor. Moreover, we analyzed research data from farmers in Fujian Province using a probit model to determine the effect of labor transfer and market development on the outsourcing of forestry production by farmers.Conclusions and discussionThe conclusions showed that several factors have a significant impact on the outsourcing of forestry production. These factors include labor transfer, market development, income level in the village, smaller machinery numbers, amount of forestry subsidies, extent of forest road construction to meet production demands, and degree of forest land fragmentation. We have discussed topics of the distribution of labor value, market structure cultivation, and forestry costs on conclusion.Policy implicationsWe propose increasing farmers’ income through labor transfer, fostering the market for outsourcing services in forestry production, and promoting the new classification of forestry.