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Wave Profile for Current Bearing Lightning Strokes 带雷击电流的波浪剖面
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7222
B. Landers, M. Hemmati, A. Alzhrani
The propagation of breakdown waves in a gas, which is primarily driven by electron gas pressure, is described by a one-dimensional, steady-state, threecomponent (electrons, ions, and neutral particles) fluid model. This study will involve waves propagating in the opposite direction of the electric field force on electrons (anti-force waves—lightning return stroke) only. We consider the electron gas partial pressure to be much larger than that of the other species and the waves to have a shock front. Our set of equations consists of the equations of conservation of the flux of mass, momentum, and energy coupled with the Poisson’s equation. The set of equations is referred to as the electron fluid dynamical equations. For breakdown waves with a significant current behind the shock front, the set of electron fluid dynamical equations and also the boundary condition on electron temperature need to be modified. For a range of experimentally measured current values and a range of possible wave speeds, we will present the method of solution of the set of electron fluid dynamical equations and also the wave profile for electric field, electron velocity, electron temperature, and number density, as well as the ionization rate within the dynamical transition region of the wave.
击穿波在气体中的传播主要由电子气压驱动,通过一维、稳态、三组分(电子、离子和中性粒子)流体模型来描述。这项研究将只涉及在电子上电场力的相反方向上传播的波(反力波——闪电回击)。我们认为电子气体的分压比其他物质的分压大得多,并且波具有激波阵面。我们的方程组由质量、动量和能量通量守恒方程和泊松方程组成。这组方程被称为电子流体动力学方程。对于在冲击前沿后面有显著电流的击穿波,需要修改电子流体动力学方程组和电子温度的边界条件。对于一系列实验测量的电流值和一系列可能的波速,我们将介绍一组电子流体动力学方程的求解方法,以及电场、电子速度、电子温度和数密度的波形,以及波的动态过渡区内的电离率。
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引用次数: 0
Distribution of the Highland Stoneroller (Campostoma spadiceum) in Southern Arkansas 阿肯色州南部高地石辊虫的分布
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7210
R. Tumlison, H. Robison
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引用次数: 2
Tree Ring Dating of the Ficklin-Imboden Log Structures, Powhatan Historic State Park, Arkansas Ficklin-Imboden原木结构的年轮年代测定,波瓦坦历史州立公园,阿肯色州
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7223
Kaylee R McAdoo, D. Stahle
Powhatan Historic State Park in Powhatan, Arkansas preserves and interprets five historical structures from 19 century Arkansas, including the Ficklin-Imboden Log House. This structure, which is actually two separate log buildings with uncertain construction dates and functions, is believed to be the earliest surviving structure at Powhatan Historic State Park and is on the National Register of Historic Places. Powhatan Historic State Park contracted with the University of Arkansas Tree-Ring Laboratory to develop a more accurate dating and interpretation of the log structures. Dendrochronology (tree-ring dating) was used to determine the true felling dates of bald cypress (Taxodium distichum) logs in both buildings. Core specimens were extracted from 22 wall logs and 16 were dated with dendrochronology. The measured ring width data were used to develop a chronology for the buildings that was then correlated against other absolutely dated tree-ring chronologies from the region. The strong correlation among the ring width time series from both structures provided evidence that the trees from which the logs were cut grew contemporaneously in the same area. The derived mean ring width chronology is highly correlated with tree-ring reconstructions of the Palmer Drought Severity Index (PDSI) across Arkansas and the central US from 1726 to 1846 and with other regional tree-ring chronologies, particularly one created from living bald cypress trees at Allred Lake in southeast Missouri. All possible correlation analyses between the continuous FicklinImboden chronology and the Allred Lake chronology, advancing one year at a time over the past 808 years (1185–1992), indicate that the highest correlation (r = 0.45) is observed precisely where the log specimens were dated based on microscopic analysis and skeleton plot crossdating. The derived cutting dates extended from 1843 to 1846, with logs in both structures cut as late as 1846. Because the structures are in situ and the wall logs have not been extensively repaired or replaced, the cutting dates indicate that the structures were likely erected simultaneously during or soon after the growing season of 1846. This date is slightly earlier than the current interpretation by Powhatan Historic State Park, but still consistent with the documentary evidence that Andrew Imboden and his wife used the building as a home by 1851.
位于阿肯色州波瓦坦的波瓦坦历史州立公园保留并诠释了19世纪阿肯色州的五座历史建筑,包括菲克林-伊姆波登木屋。这座建筑实际上是两座独立的原木建筑,建造日期和功能都不确定,被认为是波瓦坦历史州立公园现存最早的建筑,已被列入国家史迹名录。波瓦坦历史州立公园与阿肯色大学树木年轮实验室签订合同,对原木结构进行更准确的年代测定和解释。树木年代学(树木年轮测年法)测定了两座建筑中秃柏(Taxodium distichum)原木的真实砍伐日期。岩心标本取自22根岩壁,其中16根岩心标本进行了年代学测定。测量的年轮宽度数据用于开发建筑物的年表,然后将其与该地区其他绝对确定年代的树木年表相关联。两种结构的年轮宽度时间序列之间的强相关性提供了证据,证明砍伐原木的树木在同一地区同时生长。得出的平均年轮宽度年表与1726年至1846年阿肯色州和美国中部帕尔默干旱严重指数(PDSI)的树轮重建高度相关,也与其他地区的树轮年表高度相关,尤其是密苏里州东南部奥尔雷德湖的活的秃柏树年表。在过去808年(1185-1992)中,FicklinImboden连续年代学与Allred Lake年代学之间的所有可能的相关分析都表明,在基于微观分析和骨架图交叉定年的原木标本定年处,相关性最高(r = 0.45)。衍生的切割日期从1843年延伸到1846年,两个结构中的原木都是在1846年被切割的。由于这些结构还在原地,墙壁原木也没有被广泛修复或更换,因此切割日期表明,这些结构可能是在1846年生长季节期间或之后不久同时竖立起来的。这个日期比波瓦坦历史州立公园目前的解释稍早,但仍然与文献证据一致,即安德鲁·伊姆博登和他的妻子在1851年将这座建筑作为家。
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引用次数: 0
Avian Frugivory in a Fruiting Mulberry Tree (Morus rubra) in Arkansas 阿肯色一种正在结果的桑树(Morus rubra)的鸟类果实
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7219
J. L. Jackson, R. Kannan
A fruiting Mulberry tree (Morus rubra) was observed for 67 hours in the spring of 2016 and 2017 in Fort Smith, Arkansas. A total of 172 five-minute scans were performed, during which the following parameters were recorded: species visited, number of individuals of each species, time of visitations, and foraging tier. Between each scan, the foraging rate (number of fruits consumed/min) and interand intraspecific aggressive interactions were recorded. A total of 3465 observations of individual birds from 32 species was recorded. Species diversity index was higher in the upper half of the tree. The mean foraging rates for the 6 most commonly observed species ranged from 1.2-2.3 fruits/min. A total of 346 aggressive interactions was observed of which 68% were intraspecific.
2016年春季和2017年春季,在阿肯色州史密斯堡观察到一棵结果良好的桑树(红色桑椹)长达67个小时。共进行了172次5分钟的扫描,期间记录了以下参数:访问的物种、每个物种的个体数量、访问时间和觅食等级。在每次扫描之间,记录觅食率(每分钟消耗的水果数量)和种间和种内的攻击性相互作用。共记录了来自32个物种的3465个鸟类个体的观测结果。物种多样性指数在树的上半部分较高。6种最常见物种的平均觅食率在1.2-2.3个果实/分钟之间。共观察到346种攻击性相互作用,其中68%为种内相互作用。
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引用次数: 3
New Applications of Radio Frequency Identification Stations for Monitoring Fish Passage through Headwater Road Crossings and Natural Reaches 无线射频识别站在监测鱼类通过水源路口和自然河段的新应用
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7211
Ian Macleod, C. Gagen
Within the Ouachita National Forest, roads and streams intersect each other thousands of times. Many of these road crossings alter stream hydrology and potentially limit longitudinal fish movement. To investigate the potential impacts of these road crossings on fish passage, we monitored movements of 3 native fish species (n = 2,171) individually tagged with radio frequency identification (RFID) tags in 2012 and 2013. We installed solar-powered RFID stations in 2 streams with road crossings and 2 reference streams without road crossings. Each of the 4 monitoring stations included a pair of antennas bracketing a road crossing (or similarly-sized natural reach) to continuously detect upstream or downstream passage. To monitor natural reference streams, we avoided full-duplex RFID technology, which would have required rigid in-stream structures. Alternatively, we utilized new applications of RFID technology such as direct in-stream installation of half-duplex wire antennas and figure-eight crossover antenna designs. These techniques appear promising, but technical difficulties limited the consistency of fish passage detection and consequently limited the strength of ecological conclusions. Even so, we report evidence that fish passed at significantly higher rates across reference reaches than reaches with road crossings. Furthermore, Creek Chub (Semotilus atromaculatus) passed reference reaches at significantly higher rates than Highland Stonerollers (Campostoma spadiceum), which passed at higher rates than Longear Sunfish (Lepomis megalotis). Stream intermittency appeared to exacerbate reduced passage rates associated with the road crossings.
在瓦奇塔国家森林内,道路和溪流相交数千次。许多这样的道路交叉口改变了河流水文,并可能限制鱼类的纵向流动。为了调查这些道路交叉口对鱼类通道的潜在影响,我们在2012年和2013年监测了3种分别用射频识别(RFID)标签标记的本地鱼类(n=2171)的活动。我们在2条有路口的溪流和2条没有路口的参考溪流中安装了太阳能RFID站。4个监测站中的每个监测站都包括一对天线,将道路交叉口(或类似大小的自然范围)包围起来,以连续检测上游或下游通道。为了监测自然参考流,我们避免了全双工RFID技术,这将需要刚性的流内结构。或者,我们利用了RFID技术的新应用,如半双工有线天线的直接安装和八字形交叉天线设计。这些技术看起来很有前景,但技术上的困难限制了鱼类通道检测的一致性,从而限制了生态学结论的强度。即便如此,我们报告的证据表明,鱼类在参考河段的通过率明显高于有公路交叉口的河段。此外,Creek Chub(Semotilus atromaculatus)通过参考河段的比率明显高于Highland Stonerollers(Campostoma spadiceum),后者通过的比率高于Longear Sunfish(Lepomis megalotis)。溪流间歇性似乎加剧了与道路交叉口相关的通行率下降。
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引用次数: 0
Distal Urogenital Anatomy of Male Southern Coal Skinks, Plestiodon anthracinus pluvialis (Reptilia: Scincidae) 南方雄性煤石龙的远端泌尿生殖解剖(爬行纲:石龙科)
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7228
S. Trauth
I investigated the morphology and histology of the distal urogenital anatomy of male southern coal skinks (Plestiodon anthracinus pluvialis) from reproductively active individuals collected in Arkansas in order to provide comparative information with recent studies on squamate urogenital anatomy. Specifically, I focused on the basic anatomy and positioning of posterior ducts in this skink, which included portions of the ductus deferens, the ampulla ductus deferentis, the sexual segment of the kidney, the ureter and collecting ducts, as well as aspects of the urodaeal chamber and urogenital papillae. I found a much reduced ampulla ductus deferentis comprising only 0.7 mm in length in the caudal region of the ductus deferens. The sexual segment of the kidney was well developed, being located in collecting ducts of the kidney proper, in walls of collecting ducts leading away from the kidney as well as within anterior portions of the ureter. The anterior dorsal recess of the urodaeum possessed epithelial crypts within a highly folded epithelium. Finally, a ductal triad (ductus deferens, ureter, and a single collecting duct) terminates at each orifice of the paired urogenital papillae. The distal urogenital anatomy of this scincid lizard revealed anatomical features similar to other species within the genus Plestiodon.
本文研究了在美国阿肯色州收集的繁殖活跃个体的雄性南方煤石龙(Plestiodon anthracinus pluvialis)远端泌尿生殖解剖学的形态学和组织学,以便与最近的鳞片动物泌尿生殖解剖学研究提供比较资料。具体来说,我着重于这个皮肤的后导管的基本解剖和定位,其中包括部分的输尿管,壶腹管,肾的性段,输尿管和收集管,以及尿路室和泌尿生殖乳头的方面。我发现了一个缩小了很多的壶腹管在管尾区只有0.7毫米长。肾的性段发育良好,位于肾的集管中,在远离肾脏的集管壁中,以及输尿管的前部。尿道前背隐窝在高度折叠的上皮内具有上皮隐窝。最后,三联导管(输尿管、输尿管和单个集管)在成对的泌尿生殖乳头的每个孔处终止。这只蜥蜴的远端泌尿生殖解剖显示出与其他物种相似的解剖特征。
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引用次数: 1
Gene flow and genetic structure of two of Arkansas’s rarest darter species (Teleostei: Percidae), the Arkansas Darter, Etheostoma cragini, and the Least Darter, E. microperca 两个阿肯色州的基因流和遗传结构™s最稀有的镖鲈物种(Teleostei:珀科),阿肯色州镖鲈,Etheostoma cragini,和最小镖鲈E.microperca
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7213
Justin S. Baker, B. Wagner, R. Wood
Distinguishing the effects of naturally caused historical fragmentation from those of contemporary landscape modification is critically important to understanding the consequences of human influences on patterns of gene flow and population dynamics. Nonetheless, relatively few recent studies focusing on this issue have dealt with species that showed evidence of historical fragmentation. In the current study, we disentangled the effects of fragmentation operating over separate timescales on two darter species, Etheostoma cragini and E. microperca, from the Ozark Highlands. Formerly more wide-spread within this region in Arkansas, these species now occur only in highly isolated habitats (i.e., spring-runs). We separated fragmentation effects at distinct spatial and temporal scales by using several molecular loci (i.e., mtDNA/nuclear DNA/nuclear microsatellite DNA), as well as a variety of analytical approaches. Sequence divergence among Ozark and northern populations of E. microperca indicate long-standing isolation resulting from vicariant events. Both species were further isolated in unique ‘island’ habitats, sometimes at fine spatial scales, as shown by sequence divergence among Ozark Highland populations of E. cragini. Microsatellite data also revealed additional subdivision among Arkansas populations with E. cragini divided into three distinct populations and E. microperca into two. Overall, migration rates were similar among contemporary and historical time periods although patterns of asymmetric migration were inverted for E. cragini. Estimates of contemporary effective population size (Ne) were substantially lower for both species than past population sizes. Overall, historical processes involving natural fragmentation have had long-lasting effects on these species, potentially making them more susceptible to current anthropogenic impacts. Introduction Habitat fragmentation operating both over historical time scales and over more recent timescales results in species with highly fragmented distributions, significantly compromising the maintenance of genetic diversity and population viability (Keyghobadi et al. 2005; Zellmer and Knowles 2009). Distinguishing between these time scales is important to conservation efforts because knowledge of historical population structure is essential to assessing the impact of current anthropogenic effects. Several recent studies comparing past and current patterns of gene flow among populations have revealed that recent human activities have substantially altered connectivity among populations, resulting in increased bottlenecks and high levels of inbreeding (Reed et al. 2011; Apodaca et al. 2012; Blakney et al. 2014); others suggest the high levels of structure observed among populations reflect long-standing limited dispersal of the species rather than recent habitat fragmentation (Chiucchi and Gibbs, 2010). These two causes of fragmentation may also act synergistically, such that the historically fragmen
区分自然造成的历史碎片化和当代景观改造的影响,对于理解人类影响对基因流动模式和人口动态的影响至关重要。尽管如此,最近关注这一问题的研究相对较少涉及显示出历史碎片证据的物种。在目前的研究中,我们解开了在不同时间尺度上碎片化对Ozark高地的两种飞镖物种,Etheostoma cragini和E.microperca的影响。这些物种以前在阿肯色州的这一地区分布更广,现在只出现在高度孤立的栖息地(即春季迁徙)。我们通过使用几个分子位点(即mtDNA/核DNA/核微卫星DNA)以及各种分析方法,在不同的空间和时间尺度上分离了碎片效应。Ozark和北部种群的微小锥虫序列差异表明,替代事件导致了长期的孤立。这两个物种都在独特的“岛屿”栖息地被进一步隔离,有时是在精细的空间尺度上,正如克拉基尼的奥扎克高地种群之间的序列差异所示。微卫星数据还揭示了阿肯色州种群的进一步细分,cragini E.cragini被分为三个不同的种群,microperca E.被分为两个。总体而言,当代和历史时期的移民率相似,尽管克拉基尼的非对称移民模式相反。对这两个物种的当代有效种群规模(Ne)的估计大大低于过去的种群规模。总的来说,涉及自然破碎化的历史过程对这些物种产生了长期影响,可能使它们更容易受到当前人类活动的影响。引言栖息地在历史时间尺度和最近时间尺度上的碎片化导致物种分布高度碎片化,严重影响遗传多样性和种群生存能力的维持(Keyghobadi等人,2005;Zellmer和Knowles,2009年)。区分这些时间尺度对保护工作很重要,因为了解历史种群结构对于评估当前人为影响的影响至关重要。最近几项比较过去和现在种群之间基因流动模式的研究表明,最近的人类活动大大改变了种群之间的连通性,导致瓶颈增加和近亲繁殖率高(Reed等人,2011;Apodaca等人2012;Blakney等人2014);其他人认为,在种群中观察到的高水平结构反映了该物种长期有限的扩散,而不是最近的栖息地破碎化(Chiucchi和Gibbs,2010)。这两个碎片化的原因也可能协同作用,使得一个物种历史上碎片化的种群数量减少,或者由于人为影响,每个种群的成员数量都有所减少。高度分散和种群规模缩小的种群局部灭绝率很高,因此全球灭绝的可能性更高(Templeton等人,1990)。最近的碎片化也可能对集合种群的动力学产生重大影响,即使在小的空间尺度上,集合种群的动态也可能在种群之间观察到的适应性差异中发挥关键作用(Zellmer
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引用次数: 0
Primeness in Early Season Arkansas Raccoon Pelts 阿肯色州浣熊早季的黄金时段
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7218
D. Sasse
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引用次数: 0
New Records of the American Badger (Taxidea taxus) in Arkansas, with an updated distribution map 阿肯色州美国獾新记录(Taxidea taxus),附有更新的分布图
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7207
R. Tumlison, D. Sasse
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引用次数: 0
Deep Learning-based framework for Autism functional MRI Image Classification 基于深度学习的自闭症功能性MRI图像分类框架
Pub Date : 2018-01-01 DOI: 10.54119/jaas.2018.7214
Xin Yang, S. Sarraf, Ning Zhang
The purpose of this paper is to introduce the deep learning-based framework LeNet-5 architecture and implement experiments for functional MRI image classification of Autism spectrum disorder. We implement our experiments under the NVIDIA deep learning GPU Training Systems (DIGITS). By using the Convolutional Neural Network (CNN) LeNet-5 architecture, we successfully classified functional MRI image of Autism spectrum disorder from normal controls. The results show that we obtained satisfactory results for both sensitivity and specificity.
本文的目的是介绍基于深度学习的框架LeNet-5架构,并实现自闭症谱系障碍的功能MRI图像分类实验。我们在NVIDIA深度学习GPU训练系统(DIGITS)下实现我们的实验。采用卷积神经网络(CNN) LeNet-5架构,成功地将自闭症谱系障碍的功能MRI图像与正常对照进行了分类。结果表明,该方法在灵敏度和特异度上均取得了满意的结果。
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引用次数: 13
期刊
Journal of the Arkansas Academy of Science
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