Maximum Movement Distance Research Articles

Investigation of the mass movement and thermal pressurization effect of rapid and long-runout landslides in Shuicheng, Guizhou, China

The speed, distance and energy evolution of rapid and long-runout landslides are crucial indicators for evaluating the characteristics of these catastrophic landslides. The Shuicheng rapid and long-runout landslide was chosen as an example for further study, and the evolutionary process of landslide motion was simulated by PFC. The kinematic characteristics and dynamic mechanism were experimentally studied with the above three indicators, and the results indicated that the landslide lasted approximately 60 s and could be divided into four stages: uniform deformation, erosion-disintegration, block-spilt and convergence-accumulation. The speed of the landslide peaked at 36.1 m/s at 28 s. Controlled by the terrain, particles collided violently, and there was strong momentum transfer, which greatly promoted the long-runout movement of the landslide, with a maximum movement distance of 1303 m. During movement, gravitational potential energy was mainly converted into dissipated energy of friction and collision, accounting for 51.0 % and 39.6 %, respectively, of the total gravitational potential energy released during the landslide. After the landslide initiated, the apparent frictional coefficient reached a peak of 0.49 in 6 s. Then, the apparent frictional coefficient gradually decreased and stabilized at approximately 0.32. The factor leading to the decrease in the apparent frictional coefficient was the rapid increase in the dissipated energy of friction. In addition, it was found through quantitative calculation that the dissipated energy of friction generated in the propagation can cause the basal facies to rise by 65.08 °C. The results from the numerical simulations are in agreement with the findings from the field investigation, affirming the thermal pressurization impact associated with rapid and long-runout landslides. These simulations yield insights that are scientific merit for understanding the kinematics and dynamics underlying these types of landslides.

Movement of an imperiled esocid fish in an agricultural drain

Animal movement is increasingly affected by human alterations to habitat and climate change. In wetland systems, widespread hydrologic alterations from agriculture have changed the shape, function, and stability of shallow streams and wetland habitats. These changes in habitat quality and quantity may be especially consequential for freshwater fishes such as Grass Pickerel (Esox americanus vermiculatus), a small predatory fish found in disjunct populations across southern Ontario and listed as Special Concern under Canada’s Species at Risk Act. To characterize Grass Pickerel movement response to stream-channel alterations, Fisheries and Oceans Canada implemented a tracking study to monitor the movements of a Grass Pickerel population in an agricultural drain on the Niagara Peninsula (Ontario, Canada). From 2009 to 2013, 2007 Grass Pickerel were tagged and tracked in the 37.3 km2 Beaver Creek watershed using a combination of mark-recapture surveys and eight fully automated passive integrated transponder tag antennas. Most individuals moved within 500 m (i.e., stationary fish) while 16% of the fish moved > 500 m (i.e., mobile fish), with a maximum median movement distance of 1.89 km and a maximum movement distance of 13.5 km (a long-tail distribution). Most movements occurred near the largest confluence where only a few were long-distance upstream or downstream movements. Mobile fish were larger than their stationary counterparts. Grass Pickerel in sites with higher abundance had more mobile fish, implying potential density dependence. Our results highlight that, while a long-distance dispersal ability exists in extant Grass Pickerel populations, the current conditions of riverscapes may prevent these dispersals from occurring. For declining Grass Pickerel populations, limitations to their movement ecology may substantially increase the likelihood of local extirpations.

Quantitative analysis of balance function characteristics in older patients with mild to moderate cognitive impairment

BackgroundCognitive decline in older adults may affect balance function, but the relationship between the two is not fully understood, especially in the early stages of cognitive impairment. Mild to moderate cognitive impairment can be assessed with the Montreal Cognitive Assessment (MOCA). AimThis study quantitatively analyzed balance function in older adults with mild to moderate cognitive impairment using computerized dynamic posturography (CDP) testing. Methods248 older patients were divided into a cognitive impaired group (MOCA <26, n = 126) and a normal group (MOCA ≥26, n = 122) based on the Montreal Cognitive Assessment (MOCA) Beijing Version. Patients underwent CDP testing, which included the sensory organization test (SOT) and the limits of stability test (LOS). ResultsThe cognitive impaired group had significantly lower SOT composite and visual scores, as well as reaction time (RT), movement velocity (MVL), endpoint excursion (EPE), maximum excursion (MXE), and directional control (DCL) of the LOS test. Binary logistic regression analysis revealed that RT and MXE were independent factors significantly associated with MOCA, even after adjustment for age and sex. ConclusionsOlder patients with mild to moderate cognitive impairment may have reduced sensory integration and balance stability limits, mainly manifested as prolonged motor reaction time and shortened maximum movement distance.

Characteristics of submental muscles function and hyoid bone movement in patients with dysphagia after stroke.

Dysphagia is one of the common complications after stroke. Dysphagia significantly increases the probability of serious adverse consequences. The purpose of this study was to compare the characteristics of submental muscles electromyography and hyoid motion parameters between patients with dysphagia after stroke and healthy controls, and whether there is a synergistic effect between the function of the submental muscles and the movement of the hyoid. Fifteen patients with post-stroke dysphagia and fifteen healthy adults simultaneously underwent the videofluoroscopic and surface electromyography of the submental muscles while swallowing 5ml of concentrated liquid barium sulphate. The electromyographic signal of the submental muscles was analysed along with parameters of hyoid movement. Stage transition duration and duration of surface electromyographic activity were extended significantly in post-stroke dysphagia patients(P<0.05). Surface electromyography amplitude and hyoid movement were significantly reduced in patients (P<0.05). There was a significant correlation between the maximum hyoid movement distance and the peak sEMG amplitude in healthy controls (r=0.660, P=0.014), but not in patients with dysphagia after stroke (r=0.425, P=0.148). Submental muscles electromyographic signal changes in patients may be the result of uncoordinated muscle contractions and decreased muscle strength. Furthermore, the reduced hyoid movement distance may be due to impaired function of the submental muscles. In addition, the submental muscles and hyoid movement or other swallowing structures functions were impaired to varying degrees, resulting in the disappearance of the correlation between the maximum movement distance of the hyoid and the peak amplitude.

Steerable directional bouncing and contact time reduction of impacting droplets on superhydrophobic stepped surfaces

HypothesisThe unbalanced capillary force provided by wettability patterns, non-uniform/asymmetric microtextures enables directional droplet transport, while macrotextures have shown potentials in reducing the contact time. Inspired by these findings, we design millimeter superhydrophobic stepped surfaces to simultaneously achieve highly steerable directional bouncing and contact time reduction of impacting droplets. ExperimentsThe stepped surfaces are fabricated by computerized numerical control, chemical oxidation, hydrophobic treatment. Systematic impact experiments are conducted under Weber number ranging from 10.5 to 20.5, two step heights (0.5 mm and 1.0 mm) and extensive impact positions. FindingsCompared with known microtextured surfaces, the stepped surfaces exhibit excellent performance with the maximum lateral movement distance about 8 times of droplet radius, controllable rebound angle ranging from ∼ 32° to ∼ 90° and up to ∼ 30 % reduction in contact time. Particularly, we divide the directional bouncing characteristics into six regimes and attribute the variation of rebound velocity by the synergistic effects of viscous dissipation, excess surface energy, excess kinetic energy. It is demonstrated that the contact time is reduced by liquid mass redistribution and asymmetry enhancement. Predictive models of contact time that incorporate the coupling effects of impact position, impact velocity and step height are also established.

Spiral modulated groove position gratings for the generation of two focused optical vortices with equal intensity

By combining a spiral zone plate (SZP) and a modulated groove position grating (MGPG) through a single logic XOR operation, we propose and experimentally demonstrate a single optical element, termed as spiral modulated groove position gratings (SPG), to generate two tightly focused optical vortices with approximately equal intensity. The third-order diffraction light intensity can be reduced from 21.12% of the required first-order diffraction intensity to less than the intensity of background, and the dependence of the unwanted zero-order extinction and high-order diffraction suppression on the period, maximum movement distance and aperture size is investigated. The experimental results are also presented, agreeing well with the theoretical predictions, and confirm that the output beam has the helical phase structures with multiple topological charges. The unique characteristics of the proposed SPG make it attractive for many applications such as particle trapping and optical imaging.

A Study on Evaluation of Slope Stability and Range of Rockfall Hazard of Daljeon-ri Columnar Joint in Pohang, Korea

In this study, we evaluated the slope stability of the Pohang Daljeon-ri columnar joint (Natural Monuments # 415) and calculated the maximum energy, jumping height and moving distance of rockfalls using a simulation. Based on the results, we established the range of rockfall risk. The slopes of the Pohang Daljeon-ri columnar joint have dip directions of 93.79°, 131.99°, 165.54° and 259.84° from left (SW) to right (NE). Furthermore, they have a fan-like shape. The Pohang Daljeon-ri columnar joints are divided into four sections depending on the dip direction. The measurement results of the discontinuous face show that zone 1 is 125, zone 2 is 261, zone 3 is 262, zone 4 is 43. The results of slope stability analyses for each section using a stereographic projection method correspond to the range of planar and toppling failure. Although it is difficult to diagnose the type of failure, risk evaluation of currently falling rocks requires further focus. The maximum movement distance of a rockfall in the simulation was approximately 66 m and the rockfall risk range was the entire area under slope. In addition, it is difficult to forecast where a rock will fall as it rolls in various directions due to topographic factors. Thus, the installation of measures to prevent falling is suggested to secure the stability based on the results of the rockfall simulations and its probabilistic analysis.

Effect of electromyography-triggered peripheral magnetic stimulation on voluntary swallow in healthy humans.

Electrical stimulation therapy is effective for patients with dysphagia. However, because of the pain, strong stimulation cannot be applied. Although magnetic stimulation induces less pain, there are no reports on magnetic stimulation being synchronised with a swallowing reflex. This study aimed to determine whether it is possible to induce magnetic stimulation during a voluntary swallowing using electromyography (EMG)-triggered peripheral magnetic stimulation and to evaluate its effect on healthy individuals. A total of 20 healthy adults in seated position were instructed to swallow saliva and 10ml of barium under videofluoroscopy. For concomitant use of magnetic stimulation, a magnetic stimulus for suprahyoid muscles at 30Hz frequency was applied for 2s when the EMG level in the sternohyoid muscle exceeded the threshold. During the voluntary swallowing, the movement of the hyoid bone and opening width of the upper oesophageal sphincter (UES) were measured. Furthermore, pressure topography was evaluated in 6 subjects using high-resolution manometry. The magnetic stimulation significantly extended the movement time of the hyoid bone (p<0.001). During liquid deglutition, significant increases were observed in the anterior maximum movement distance of the hyoid bone (p<0.05), opening width of the UES (p<0.001) and anterior movement distance of the hyoid bone at the maximum UES opening (p<0.01). In the pressure topography, the maximum pressure immediately after UES closure significantly decreased with magnetic stimulation (p<0.05). EMG-triggered peripheral magnetic stimulation made it possible to apply magnetic stimulation during a voluntary swallowing.

Energy-Efficient Swarming Flight Formation Transitions Using the Improved Fair Hungarian Algorithm.

Recently, drone shows have impressed many people through a convergence of technology and art. However, these demonstrations have limited operating hours based on the battery life. Thus, it is important to minimize the unnecessary transition time between scenes without collision to increase operating time. This paper proposes a fast and energy-efficient scene transition algorithm that minimizes the transition times between scenes. This algorithm reduces the maximum drone movement distance to increase the operating time and exploits a multilayer method to avoid collisions between drones. In addition, a swarming flight system including robust communication and position estimation is presented as a concrete experimental system. The proposed algorithm was verified using the swarming flight system at a drone show performed with 100 drones.

Numerical analysis of dynamic characteristics of sludge-type slag landfill landslide

The Artificial landfill landslide in Guangming District, Shenzhen, which occurred on December 20, 2015, showed the same characteristics as mudflow after sliding, which had long sliding movement distance and large coverage area, and caused serious casualties and property losses. Therefore, research on the dynamic characteristics of artificial accumulation landslide is of great significance for landfill slope hazard assessment and prevention in urban construction. On the basis of detailed collection of landslide investigation data and field investigation, the motion of the landslide was simulated with the friction rheological model by the software DAN-W in this paper, in order to obtain the characteristic parameters of landslide movement. The results showed that, the maximum movement distance was 1,112 meters and a running time of 105s simulated by friction model. The maximum front velocity was 22.5m/s and occurred at a horizontal distance of 632 meters. The horizontal length of the accumulation mass was 580 meters and the average thickness was about 8.2m. The numerical simulation results are basically consistent with the field survey results. The simulation model and the motion characteristic parameters of the muck can be used as reference for the prevention and control design of slope of similar muck field.

Evaluation of Beef Cattle Temperament Using Video Technology

HighlightsVideo processing technology was used to evaluate beef cattle temperament objectively.Multiple beef cattle temperament methods were compared with video processing technology.Potential automatic temperament evaluation systems could be developed based on our video processing method.Abstract. Cattle temperament has potential impacts on growth, carcass characteristics, and meat quality. Both objective and subjective methods have been used to assess temperament, such as temperament score (TS), docility score (DS), flight speed (FS), and exposed eye white percentage (EW). Subjective methods for evaluating cattle temperament are labor-intensive and potentially stressful for the animals. Video technology (VT) has advantages of being noninvasive, automated and remotely operable, and compatible with cloud-based complex algorithms, which facilitates immediate field deployment of results. Because VT has not been reported as a beef cattle temperament evaluation method, the objectives of this study were to (1) verify the feasibility of VT as an evaluation method for beef cattle temperament, and (2) assess the accuracy and reliability of the VT measurements in comparison with TS and DS. A total of 170 calves were video recorded while they were in a squeeze chute; simultaneously, DS and TS measurements of the same calves were conducted. Maximum movement distance (MMD), average movement distance (AMD), and moving frequency (MF) were calculated according to the distances measured from the videos using an algorithm developed in this research. Pearson correlation coefficients among MMD, AMD, MF, TS, and DS were calculated and were 0.264 (p &amp;lt; 0.001) for DS versus TS, 0.438 (p &amp;lt; 0.001) for MF versus TS, 0.017 (p = 0.838) for AMD versus DS, 0.107 (p = 0.192) for AMD versus TS, 0.058 (p = 0.481) for MMD versus DS, and 0.077 (p = 0.350) for MMD versus TS. This study showed that MF could be a good indicator for assessing cattle temperament coupled with VT as a quantitative tool, requiring minimal equipment and thus providing an objective method for selecting cattle with appropriate temperaments. Keywords: Beef cattle, Temperament, Video technology.

P662 Synchrony between the right and left heart systems is recovered after TAVI in patients with severe aortic stenosis

Abstract Funding Acknowledgements Young Investigator Grant of Japanese Society of Cardiovascular Anesthesia Background / Introduction Evidences have shown that cardiac function decline and systolic phase change are caused by massive afterload of the stenosed aortic valve in patients with severe aortic valve stenosis. As a result of the reduction of the left ventricular afterload by valve replacement, the cardiac function recovers. However, it has not been clarified yet how the changes in cardiac function affect the relationship between the right and left heart systems, as well as the systole phase. TAPSE and MAPSE are known as indices of simple cardiac function evaluation by measuring the movement distance of the atrioventricular annulus. We obtained these indices (i.e. TAPSE, MAPSE) within the same heartbeat using speckle tracking analysis of the atrioventricular annulus and evaluated the changes in cardiac function and phase between the right and left heart systems. Purpose To reveal the relationship of cardiac function and time phase between the right and left heart systems by evaluating the maximum movement distance and time of the atrioventricular annulus within the same heartbeat and the same view in patients with severe aortic valve stenosis before and after TAVI. Methods A prospective cohort study was conducted. We recruited and analyzed 44 patients with severe aortic valve stenosis who received TAVI treatment, able to record baseline before treatment and follow-up 6 months and 12 months after treatment at our hospital from March 2017 to May 2019. Patients were excluded if more than 2 degree of atrioventricular valve regurgitation or incomplete data. The apical four-chamber view was used for speckle tracking analysis with the origin of the apical extension and region of interest (ROI) of the mitral annulus and tricuspid annulus. For each patient before treatment, at 6 months and 12 months after treatment, the maximum contraction distance (DM), maximum contraction time (TM) of the mitral valve annulus, maximum contraction distance (DT) and maximum contraction time (TT) of the tricuspid annulus were measured. Maximum contraction distance ratio (DM/ DT) and maximum contraction time ratio (TM/ TT) were calculated. For statistical analysis, t-test and ANOVA were used, and a significance threshold of p &amp;lt;0.05 was applied. Results TM/ TT decreased at 12 months after TAVI, and DM/ DT increased significantly at 6 months and 12 months after TAVI when compared to baseline before treatment. Conclusions In patients with severe aortic valve stenosis, the correction of cardiac function difference between the right and left heart systems occurs from 6 months after TAVI. Moreover, the correction of contraction phase difference between the right and left heart systems at 12 months after TAVI. Thus, the synchrony between the right and left heart system is recovered 12 months after TAVI. Abstract P662 Figure.

The Mobile Server Problem

We introduce the Mobile Server problem, inspired by current trends to move computational tasks from cloud structures to multiple devices close to the end user. An example of this is embedded systems in autonomous cars that communicate to coordinate their actions. Our model is a variant of the classical Page Migration problem. More formally, we consider a mobile server holding a data page. The server can move in the Euclidean space (of arbitrary dimension). In every round, requests for data items from the page pop up at arbitrary points in the space. The requests are served, each at a cost of the distance from the requesting point and the server, and the mobile server may move, at a cost D times the distance traveled for some constant D . We assume a maximum distance m that the server is allowed to move per round. We show that no online algorithm can achieve a competitive ratio independent of the length of the input sequence in this setting. Hence, we augment the maximum movement distance of the online algorithms to (1+&amp;delta) times the maximum distance of the offline solution. We provide a deterministic algorithm that is simple to describe and works for multiple variants of our problem. The algorithm achieves almost tight competitive ratios independent of the length of the input sequence. Our algorithm also achieves a constant competitive ratio without resource augmentation in a variant where the movement of clients is also restricted.

Cumulative impacts of high intensity reclamation in Bohai Bay on tidal wave system and its mechanism

Contiguous mudflats exist along the coast zone of the Bohai Bay in the western part of the Bohai Sea of China. They are generally suitable for land reclamation, which can ease the contradiction between land resource shortage and the demand for development, because mudflats are important geomorphological systems which provide land resources. The shoreline at the Bohai Bay has experienced significant changes since 2003 due to high intensity reclamation. Environmental impacts of reclamation at different stages, especially on the tidal wave system, have attracted worldwide attention. However, there is still a lack of understanding on the cumulative response process of the tidal wave system and its response mechanism to high intensity development of mudflats. In this study, six periods were selected as representative reclamation stages in the Bohai Bay: 2003, 2006, 2012, future planning, and 0 m and −5 m reclamation stages. A two-dimensional tidal wave mathematical model was developed to analyze the cumulative changing process and dominant mechanism of the change of the tidal wave system by comparing effects of reclamation of the entire bay and cumulative effects of sequential reclamation projects, as well as studying the relations between the tidal wave change and tidal range on the shore segment where the reclamation project is located. Based on the analysis results, the influence of reclamation in the Bohai Bay on the M2 constituent tide was much greater than that on the K1 constituent tide, especially on the M2 constituent tide amphidromic point outside of the Yellow River mouth. The movement distance of the M2 constituent tide amphidromic point outside the Yellow River mouth for the aforementioned reclamation stages compared to its location in 2003 was about 1, 10, 22.5, 27.3, and 83.8 km, respectively. In contrast, the maximum movement distance of the other M2 constituent tide amphidromic point outside Qinhuangdao and the unique K1 constituent tide amphidromic point in the Bohai Sea for the aforementioned reclamation stages compared to their conditions in 2003 were about 5.9 and 6.3 km, respectively. With the increase of the reclamation scale, the M2 constituent tide amphidromic point outside of the Yellow River mouth first moved southeastward, and then moved northeastward, and the tidal range of the western Bohai Bay first increased and then decreased, while the speed of tidal wave propagation first accelerated and then stabilized during the 0 m reclamation stage. During the −5 m reclamation stage, the tidal wave system experienced obvious changes, however, the tidal properties inside the bay remained the same. The average tidal current velocity of the bay decreased with the increase of the reclamation scale, and the tidal current velocity of 2003, 2012, future planning and −5 m reclamation stages were 0.33–0.37, 0.3–0.34, 0.29–0.31, and 0.16–0.17 m/s, respectively. When reclamation projects were performed one by one counterclockwise from Caofeidian (future planning) in the north to south until all the future planned reclamation projects were completed, the M2 constituent tide amphidromic point first moved southwestward, and then moved southeastward. In semi-closed bays influenced by rotational tidal wave, the impact intensity of reclamation projects to the tidal wave system depends mostly on the tidal range of the coast where the reclamation projects are located. The greater the tidal range, the more obvious the effects of the reclamation projects will be on the tidal wave system. Continuous reclamation will increase flooding risks and tendency of siltation in the bay, weaken the water exchange rate in the bay, affect scouring and silting, as well as impact the design and defense standards of coastal engineering projects near the Yellow River mouth.

Secondary dispersal of forest herb seeds from raccoon dung: contrasting service by multiple vectors

Secondary movement of seeds deposited in dung potentially improves their chances of seedling establishment but has rarely been documented in temperate-zone deciduous forest. We followed mayapple (Podophyllum peltatum) seeds after deposition in raccoon (Procyon lotor) dung to test for secondary dispersal in a long-established deciduous forest in southeastern Ohio, USA. Marked seeds were incorporated into raccoon dung, placed in natural forest sites, and observed at regular intervals until the subsequent Spring. Abiotic seed movement was monitored during natural and simulated rain events. To identify animal vectors and describe their interaction with seeds, motion-triggered wildlife cameras were trained on dung with embedded mayapple seeds. Seed movement was initially limited by adhesion in the viscid dung matrix, but 15% of seeds eventually moved >20 cm from the point of placement, a minimal estimate of a shoot’s competitive neighborhood (maximum movement distance = 130 cm). Significantly greater movement occurred on slopes and in the absence of leaf litter. Rainfall moved seeds as far as 51 cm. White-footed mice (Peromyscus leucopus) and chipmunks (Tamias striatus) began removing seeds within 24 h of dung placement, presumably caching a portion of them outside the 1.5-m radius of observation. At least four other animal species interacted with dung in ways unrelated to seed presence, which nevertheless resulted in seed movement on a scale of centimeters. Thus, multiple secondary processes caused seed movement, each resulting in a distinctive seed distribution. The forest herb potentially benefits through reduction in seed density and distribution to a variety of microsites.

Node localization algorithm of wireless sensor networks with mobile beacon node

When maximum movement distance of beacon node is limited, in order to improve the localization accuracy of sensor nodes, node localization algorithm of wireless sensor networks with mobile beacon node (NLA_MB) is proposed. NLA_MB algorithm divides the movement area of beacon node into some hexagonal grids, and establishes optimization model of node localization errors according to the movement path constraint, movement distance constraint and other constraints of beacon node. Beacon node uses heuristic method to solve the model approximately based on virtual force theory and location information of guide sensor nodes, and obtains a moving path which is suitable for the current node distribution. According to location information of beacon node or anchor sensor nodes, sensor nodes use maximum likelihood estimation algorithm to calculate their own location coordinates. Simulation results show that NLA_MB algorithm is suitable for the distribution scenarios of sensor nodes, such as full coverage distribution, L-type distribution, Tian-type distribution and U-type distribution. It can increase the number of sojourn locations of beacon node and average number of anchor points of sensor nodes, and reduce average localization error of sensor nodes. Under certain conditions, NLA_MB algorithm outperforms DOUBLE_SCAN, ZSCAN, MLE, RSCAN and DBMS algorithms.

Spatial ecology of a herd of white-lipped peccaries (Tayassu pecari) in Belize using GPS telemetry: challenges and preliminary results

The Maya Mountains are a heavily forested mountain range in Belize and Guatemala supporting high levels of biodiversity. Due to environmental degradation around the range, it is in danger of becoming isolated from the largest contiguous forest in Central America. Forest connectivity in the area is vital for white-lipped peccaries. These social ungulates roam in herds of up to 300 individuals and need large forested areas to sustain populations. The species has not previously been studied in Belize and its distribution, population size, herd dynamics and movement patterns are unknown for the country. We aimed to estimate home range size and investigate movement patterns of the species in southern Belize. We present a preliminary 4-month data set from a herd of ca. 60 animals tracked by an individual fitted with a GPS satellite collar. We evaluated collar performance, habitat preference and movement characteristics, and estimated home range size using a semi-variogram approach, suited for sparse and irregular data. Collar performance was poor, with 38 % of the data not reaching the satellite, and a GPS fix success rate of 11.6 % for the data that did reach the satellite. The semi-variogram home range size was 55.2 km2. We observed a maximum daily movement distance of 3.8 km, and a preferential use of forest habitat over shrubland, savannah and cropland. We calculated a density of 1.09 ind/km2 and make an informed guess of close to 100 herds in the broad-leaf forests of the Maya Mountains. Our study highlights some of the challenges faced when collaring white-lipped peccaries, as well as the performance of GPS-collars in tropical forests. It also provides a first glimpse of the home range and movement behaviour of white-lipped peccaries in Belize.

千岛湖岛屿社鼠的扩散特征

PDF HTML阅读 XML下载 导出引用 引用提醒 千岛湖岛屿社鼠的扩散特征 DOI: 10.5846/stxb201407061386 作者: 作者单位: 浙江师范大学生态研究所,浙江师范大学生态研究所,浙江师范大学生态研究所,浙江师范大学生态研究所,浙江师范大学生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 浙江省自然科学基金(Y507080); 国家自然科学基金项目(31200323); 浙江省自然科学青年基金(LQ12C04001) Dispersal characteristics of populations of Chinese white-bellied rats (Niviventer confucianus) in the Thousand Island Lake region Author: Affiliation: Institute of Ecology,Zhejiang Normal University,Institute of Ecology,Zhejiang Normal University,Institute of Ecology,Zhejiang Normal University,Institute of Ecology,Zhejiang Normal University,Institute of Ecology,Zhejiang Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:2009年7月-11月,2010年3月-11月对千岛湖两个岛屿上的社鼠(Niviventer confucianus)种群进行标志重捕,通过分析扩散个体的性别、年龄及扩散距离等,探讨陆桥岛屿环境下社鼠的扩散特征。研究结果显示:岛屿环境下社鼠的扩散率为37.96%,不同季节社鼠的扩散率存在差异,社鼠倾向于在春季发生扩散,尤其是3月份,社鼠扩散个体数最多;对于整个捕获史而言,雌雄扩散个体数存在极显著的差异(X2=12.542,df=1,P<0.001),雄性个体更倾向于发生扩散;而在繁殖高峰期,当怀孕鼠存在时,雄性扩散数亦大于雌性,两者存在显著差异(X2=4.504,df=1,P=0.034)。扩散个体体重的季节差异不显著;扩散与社鼠的年龄密切相关,社鼠更加倾向于在亚成年阶段发生扩散;另外,家群大小对社鼠扩散个体数量也有显著影响,家群越大,扩散个体越多;对扩散距离进行分析发现存在显著的性别差异(t=-9.229,df=50,P<0.001),雌性个体的平均扩散距离为(282.97±16.14) m,显著大于雄性的(146.70±6.80) m,而扩散距离与年龄、体重、最大活动距离均无显著相关性。 Abstract:We trapped two populations of Niviventer confucianus in the Thousand Island Lake region using the capture-mark-recapture (CMR) method from July to November 2009 and from March to September 2010, and explored the dispersal characteristics of the N. confucianus populations. The Biotas 2.0 software was used to calculate the dispersal distance. The X2 test was used to analyze the effects of sex, season, and age on the number of dispersers. One-way analysis of variance (ANOVA) was used to analyze the seasonal differences in body weight of the dispersers and the effects of age on the dispersal distance. The t test for independent samples was used to analyze the body weight differences between dispersers on two islands in the same season and the effect of sex on the dispersal distance. Linear regression analysis was used for correlation analysis. Our results showed that the dispersal ratio of N. confucianus was 37.96%, which is much higher than that of the Meriones unguiculatus and Microtus fortis that lived in the mainland. We considered the possibility that food and space limitations on the islands may lead to a dispersal ratio that is higher than that of mainland populations. The dispersal ratio showed significant differences among seasons, and the dispersal peak occurred in the spring, especially in March. Other studies showed that the peak breeding of N. confucianus occurs in April and May. We believe that the breeding behavior was fully active in the spring, contributing to the larger population size, and the breeding pressure led to the dispersal of some individuals. Sex-biased dispersal was detected, and the males were more likely to disperse (X2 = 12.542,df = 1,P < 0.001). We assumed that more males dispersed in order to avoid inbreeding or to get more breeding opportunities, but this notion still needs genetic verification. A significant difference was found in the breeding period (X2 = 4.504,df = 1,P = 0.034) when the pregnant rats were counted, which means that the pregnant females affected the dispersal model during the breeding period. Compared to the immature males at the subadult stage, sexually mature males were likely to disperse. The body weight showed no significant difference between the two sexes. The number of dispersers was related to their age, and more dispersers were found in the subadult group than in the other groups. The juvenile group was limited by their capacity for activity, and the adult group had enough food and spousal resources for their dominant positions in the population, but the subadult group exerted stronger pressure on food resources and reproductive opportunities. There was a significantly positive correlation between the number of dispersers and the size of social groups: the larger social group contained more dispersers. Social-group size reflected the level of competitive pressure on spouse resources, which meant that the social pressure may be the reason for dispersal of N. confucianus. The dispersal distance showed a highly significant difference between males and females: the dispersal distance of females ((282.97±16.14) m) was greater than that of males ((146.70±6.80) m). This phenomenon may be caused by the promiscuity system of N. confucianus or avoidance of inbreeding. Female offspring tended to disperse farther away from the maternal nest to claim a new territory in order to avoid resource competition, while reducing the inbreeding probability. The dispersal distance showed no significant relation with age, body weight, and the maximum movement distance. 参考文献 相似文献 引证文献

Study of the Dynamic Characteristics of Landslides Based on the DAN-W Model

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