Canals

运河
  • 文章类型: Journal Article
    水流量(排放)可以通过影响水性污染物的浓度和运输来影响水质。放电对管理运河中磷(P)和颗粒浓度的影响,使用浓度-放电(C-Q)关系进行描述,悬浮和沉降颗粒的积累,以及这些颗粒和床层沉积物的物理化学特征。对C-Q关系的分段回归分析显示,斜率拐点表示阈值,其中P行为从低放电变为高放电。C-Q关系通常在较高的放电下显示较高的浓度。在研究的四条下大沼泽地运河中的三条中,长期(1995-2019年)较低时间分辨率数据(每日至每周)足以描述放电对P浓度的影响.然而,在一个网站,L-29运河,更高的时间分辨率数据(几周内的几分钟到几小时),来自声学传感器,是产生C-Q关系所必需的。在L-29运河,排放影响了运输,沉降,和沉积物积累在离S333流入结构的距离处。沉积物捕集器显示出更高的排放量,导致更多的悬浮颗粒积累,这些颗粒被运输并沉降到下游。一般来说,L-29运河下游表层沉积物有机质较多,比上游站点更低的堆积密度和更高的TP,反映放电的长期影响。了解放电对颗粒和相关营养素的影响,特别是在导致浓度增加的放电阈值,可以告知管理运河的运营,以减少下游敏感生态系统的污染物负荷。
    Water flow (discharge) can affect water quality by influencing the concentration and transport of waterborne contaminants. The effects of discharge on phosphorus (P) and particle concentrations in managed canals, were described using concentration-discharge (C-Q) relationships, accumulation of suspended and settling particles, and the physicochemical characteristics of these particles and bed sediments. Piecewise regression analysis on C-Q relationships revealed slope inflections that denoted thresholds, where P-behavior changed from low to high discharge. The C-Q relationships generally showed higher concentrations at higher discharges. In three of the four Lower Everglades canals studied, long-term (1995-2019) lower temporal resolution data (daily to weekly) was adequate to describe the influence of discharge on P concentrations. However, in one site, the L-29 Canal, higher temporal resolution data (minutes to hours over weeks), derived from acoustic sensors, was necessary to produce C-Q relationships. In the L-29 Canal, discharge affected the transport, settling, and sediment accrual at distances from the S333 inflow structure. Sediment traps showed higher discharge led to a greater accumulation of suspended particles that were transported and settled farther downstream. Generally, downstream surface sediments in the L-29 Canal had greater organic matter, lower bulk density and higher TP than those of the upstream site, reflecting long-term effects of discharge. Understanding the effects of discharge on particles and associated nutrients, especially at discharge thresholds that lead to concentration increases, can inform the operation of managed canals to reduce contaminant loading to downstream sensitive ecosystems.
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  • 文章类型: Journal Article
    测量总悬浮沉积物(TSS)和总颗粒磷(TPP)的常规方法通常分辨率低,错过了影响其在水生环境中出口的关键过程。为了创建高分辨率的TSS和TPP估计,回声强度(EI),声学设备的速度测量的副产品,被利用。在南佛罗里达的L-29运河的三个位置部署了声学多普勒测速仪(ADV)和声学多普勒电流分析仪(ADCP),美国,为了获得运河床附近和水柱中的估计值,分别。由于测得的EI的垂直可变性较低,因此没有必要对ADCP的传输损耗进行校正。EI校准是使用从床层沉积物(ADV)获得的人工创建的TSS和从与ADCP部署的深度和时间相匹配的水样中重量测量的TSS进行的。然后分析测量的TSS值的总磷并转化为TPP估计值。结果表明,高TSS和TPP是由典型的管理运河的快速放电释放引起的。这项工作表明,高分辨率估计对于评估这种快速水文变化对沉积物和养分向下游脆弱生态系统的潜在出口的影响至关重要。
    Conventional methods of measuring total suspended sediments (TSS) and total particulate phosphorus (TPP) are typically low-resolution and miss critical processes that impact their exports in aquatic environments. To create high-resolution TSS and TPP estimates, echo intensity (EI), a biproduct of velocity measurements from acoustic devices, was utilized. An acoustic Doppler velocimeter (ADV) and an acoustic Doppler current profiler (ADCP) were deployed in three locations in the L-29 Canal in South Florida, USA, to obtain estimates near the canal bed and in the water column, respectively. Corrections for transmission losses from the ADCP proved unnecessary due to the low vertical variability in the measured EI. EI calibrations were performed using artificially created TSS obtained from bed sediments (ADV) and gravimetrically measured TSS from water samples that matched the depths and times of the ADCP deployments. The measured TSS values were then analyzed for total phosphorus and converted to TPP estimates. The results showed that high TSS and TPP were caused by the rapid discharge releases typical of managed canals. This work demonstrates that high-resolution estimates are imperative for assessing the effects of such swift hydrologic changes on the potential export of sediments and nutrients to delicate ecosystems downstream.
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  • 文章类型: Journal Article
    Single visit endodontics offers many advantages over multi visit treatment. Therefore, it is of interest to assess the preference of single visit over multiple visit root canals. We used 86,000 patient records and selected 9017 records matching the inclusion criteria for the analysis using statistical tools (Chi square test at p value <0.05). Data shows that people between 26 to 45 years are often affected with dental caries. Available data is biased towards multi visits rather than single visit regardless number of canals.
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  • 文章类型: Journal Article
    With a focus on five sites in an impaired, densely populated area in the New Orleans area, we investigated the temporal and spatial variability of standard FIB and a marker of human-associated pollution (Bacteroides HF183). With all sites combined, only a weak positive correlation (r = 0.345; p = 0.001) was observed between E. coli and HF183. Also, specific conductivity (r = - 0.374; p < 0.0001) and dissolved oxygen (r = - 0.390; p < 0.0001) were observed to show a weak moderate correlation with E. coli. These correlations increased to moderately negative when HF183 was correlated with specific conductivity (r = - 0.448; p < 0.0001) and dissolved oxygen (r = - 0.455; p < 0.0001). E. coli contamination was generally highest at the sites in the canal that are situated in the most densely populated part of the watershed while HF183 was frequently detected across all sites. E. coli concentrations were significantly higher (p < 0.05) when HF183 was present. HF183 was detected at significantly higher concentrations in samples that exceeded the EPA water quality standard (WQS) than those that did not (p < 0.05). Dissolved oxygen and specific conductivity were significantly lower when E. coli WQS was exceeded or when HF183 was present (p < 0.05). Rainfall impacted E. coli concentrations and HF183 differently at the study sites. While HF183 and E. coli concentrations levels were significantly higher (p < 0.05) if the days prior to sampling had been wet, the frequency of detection of HF183 was unimpacted, as comparable detection rates were recorded during wet and dry weather conditions. Without testing for HF183, it would have been assumed, based on testing for E. coli alone, that human fecal pollution was only associated with densely populated areas and rainfall events. E. coli alone may not be an effective indicator of sewage pollution at the study sites across all weather conditions and may need to be complemented with HF183 enumeration to optimize human fecal pollution identification and management at the watershed level.
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  • 文章类型: Journal Article
    本研究的目的是确定甲基丙烯酸酯树脂牙本质结合剂粘附到具有32%磷酸(PA)或17%乙二胺四乙酸(EDTA)的制备和调节的根管的牙本质表面的能力。
    在施加甲基丙烯酸酯树脂之前,54根完整的根管,无龋齿,单根,取消加冕,提取的人上颌切牙和犬齿进行牙髓处理,并用32%PA或17%EDTA或用蒸馏水作为非条件对照。将树脂处理的根部在三个水平上进行横切,并在60-90倍放大倍数下对根管的圆周视图进行扫描电子显微镜(SEM)成像,并在250倍放大倍数下对特定部位的视图进行成像。然后随机编码,由四名校准的审查员进行独立和盲目的评估。数字测量了没有树脂粘附的根管的圆周表面,并从数字测量的总根管周长中减去,树脂附着力表示为周长的百分比。
    PA组树脂粘合的平均百分比为97%,EDTA组为94%,对照组为76%。PA之间的差异有统计学意义,EDTA,和对照组。
    用32%PA或17%EDTA调理的根管比未调理的根管具有更多的树脂附着力。用32%PA调理的根管比用17%EDTA调理的根管具有更高的树脂附着力。
    UNASSIGNED: The purpose of this study was to determine the ability of a methacrylate resin dentin bonding agent to adhere to the dentin surfaces of prepared and conditioned root canals with either 32% phosphoric acid (PA) or 17% ethylenediaminetetraacetic acid (EDTA).
    UNASSIGNED: Prior to the application of the methacrylate resin, the root canals of 54 intact, caries-free, single- rooted, de-crowned, extracted human maxillary incisor and canine teeth were endodontically prepared and conditioned with either 32% PA or 17% EDTA or with distilled water as the unconditioned control. The resin-treated roots were cross-sectioned at three levels and scanning electron microscope (SEM) imaged for circumferential views of the root canals at 60-90× magnification and site-specific views at 250× magnification, and then randomly coded for independent and blind evaluation by four calibrated examiners. The circumferential surface of the root canals that showed no resin adhesion were digitally measured and subtracted from the digitally measured total root canal circumference, and resin adhesion was expressed as a percentage of the circumference.
    UNASSIGNED: The mean percentages of resin adhesion were 97% for the PA group, 94% for the EDTA group, and 76% for the control group. There were statistically significant differences among the PA, EDTA, and control groups.
    UNASSIGNED: Root canals conditioned with 32% PA or 17% EDTA had more resin adhesion than unconditioned root canals. Root canals conditioned with 32% PA had more resin adhesion than those conditioned with 17% EDTA.
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  • 文章类型: Journal Article
    Temporal bone microanatomy is a common source of consternation for radiologists. Serpentine foramina, branching cranial nerves, and bony canals containing often clinically relevant but often miniscule arterial branches may all cause confusion, even among radiologists familiar with temporal bone imaging. In some cases, the tiniest structures may be occult or poorly visualized, even on thin-slice computed tomography (CT) images. Consequently, such structures are often either ignored or mistaken for pathologic entities. Yet even the smallest temporal bone structures have significant anatomic and pathologic importance. This paper reviews the anatomy and function of the temporal bone aqueducts, canals, clefts, and nerves, as well as the relevant developmental, inflammatory, and neoplastic processes that affect each structure.
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  • 文章类型: Journal Article
    目的:比较最近推出的M-Pro旋转文件与RaCe旋转文件在弯曲运河中的抗弯循环疲劳性能和断裂段(FL)的长度,并通过扫描电子显微镜(SEM)评估断裂表面。
    方法:使用了36个具有相同尖端尺寸和锥度(尺寸为25,锥度为0.06)的牙髓文件。将样品分为2组(n=18):M-Pro组(M-ProIMD)和RaCe组(FKG)。制作了定制的模拟运河模型,以评估故障循环的总数和FL。SEM用于检查破碎段的断裂表面。对数据进行统计学分析,并采用独立的Studentt检验对2组正态分布数值变量进行比较。小于0.05的p值被认为指示统计学显著性。
    结果:M-Pro组显示出比RaCe组明显更高的抗弯曲循环疲劳性(p<0.05),但两组之间的FL无显著差异(p≥0.05)。
    结论:镍钛器械的热处理可以提高旋转牙髓牙髓的抗弯循环疲劳性,M-Pro旋转系统似乎是一个有前途的旋转牙髓文件。
    OBJECTIVE: To compare the flexural cyclic fatigue resistance and the length of the fractured segments (FLs) of recently introduced M-Pro rotary files with that of RaCe rotary files in curved canals and to evaluate the fracture surface by scanning electron microscopy (SEM).
    METHODS: Thirty-six endodontic files with the same tip size and taper (size 25, 0.06 taper) were used. The samples were classified into 2 groups (n = 18): the M-Pro group (M-Pro IMD) and the RaCe group (FKG). A custom-made simulated canal model was fabricated to evaluate the total number of cycles to failure and the FL. SEM was used to examine the fracture surfaces of the fragmented segments. The data were statistically analyzed and comparisons between the 2 groups for normally distributed numerical variables were carried out using the independent Student\'s t-test. A p value less than 0.05 was considered to indicate statistical significance.
    RESULTS: The M-Pro group showed significantly higher resistance to flexural cyclic fatigue than the RaCe group (p < 0.05), but there was no significant difference in the FLs between the 2 groups (p ≥ 0.05).
    CONCLUSIONS: Thermal treatment of nickel-titanium instruments can improve the flexural cyclic fatigue resistance of rotary endodontic files, and the M-Pro rotary system seems to be a promising rotary endodontic file.
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  • 文章类型: Journal Article
    冰川底部融水的分布和排水敏感地影响着快速的冰流。先前的研究表明,上覆的冰和硬岩床之间的薄融水膜通过融化上覆的冰而被引导成有效的排水元件。然而,这些研究没有考虑在许多南极西部冰流下观察到的软可变形沉积物的存在,以及沉积物与融水排水表现出的不可分割的耦合。我们的工作提出了一种替代机制,用于启动排水元素,例如运河,其中融水膜通过侵蚀下面的沉积物而生长。我们对在易蚀床上流动的融水膜进行线性化稳定性分析。我们求解薄膜流的Orr-Sommerfeld方程,我们用Exner方程计算床演化。我们确定了一种状态,在该状态下,水文和泥沙运移的耦合动力学驱动了形态不稳定性,从而在床层产生了空间异质性。我们表明,这种薄膜不稳定性的时间尺度比Walder提出的经典热不稳定性要快得多。我们使用易蚀床上波纹形成的框架来讨论不稳定性的物理学。
    The distribution and drainage of meltwater at the base of glaciers sensitively affects fast ice flow. Previous studies suggest that thin meltwater films between the overlying ice and a hard-rock bed channelize into efficient drainage elements by melting the overlying ice. However, these studies do not account for the presence of soft deformable sediment observed underneath many West Antarctic ice streams, and the inextricable coupling that sediment exhibits with meltwater drainage. Our work presents an alternate mechanism for initiating drainage elements such as canals where meltwater films grow by eroding the sediment beneath. We conduct a linearized stability analysis on a meltwater film flowing over an erodible bed. We solve the Orr-Sommerfeld equation for the film flow, and we compute bed evolution with the Exner equation. We identify a regime where the coupled dynamics of hydrology and sediment transport drives a morphological instability that generates spatial heterogeneity at the bed. We show that this film instability operates at much faster time scales than the classical thermal instability proposed by Walder. We discuss the physics of the instability using the framework of ripple formation on erodible beds.
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  • 文章类型: Journal Article
    我们专注于一条英国运河上的案例研究,比较了环境DNA(eDNA)的元编码与两种类型的电钓鱼技术(涉水触达和动臂船)。除了通过电钓鱼获得的确证数据之外,eDNA提供了更广泛的鱼类组合快照。考虑到运河的半粘性,我们鼓励使用eDNA作为一种快速且具有成本效益的工具来检测和监测整个鱼类群落。
    We focus on a case study along an English canal comparing environmental DNA (eDNA) metabarcoding with two types of electrofishing techniques (wade-and-reach and boom-boat). In addition to corroborating data obtained by electrofishing, eDNA provided a wider snapshot of fish assemblages. Given the semi-lotic nature of canals, we encourage the use of eDNA as a fast and cost-effective tool to detect and monitor whole fish communities.
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  • 文章类型: Journal Article
    目的:本研究的目的是用四种不同的文件系统来制备和封闭上颌第一磨牙近中颊根的弯曲管,旋转锥度(RP)文件,heroshaper手文件,和旋转英雄整形器文件,并通过锥形束计算机断层扫描(CBCT)评估其单锥形Gutta-percha的适应性。
    方法:选择80颗牙齿,分为两组(G1A1,G1A2和G2A1,G2A2作为手和RP文件系统,G1A3,G1A4和G2A3,G2A4作为手动和旋转英雄整形机文件系统)每个第四齿。进入开口后,建立了中颊管的工作长度。使用分叉水平的金刚石圆盘去除样品的远颊和腭根。使用“Endoanalyser”软件在术前X光片上测量施耐德角度。这个角度是通过画两条线来测量的,一条线平行于运河的长轴,在第三日冕,和根尖孔的第二条线与第一条线离开运河长轴的点相交。然后根据制造商的说明书准备每组的运河,RP文件,heroshaper手文件,和旋转英雄塑造者文件系统。获得所有样品的直接数字射线照相图像。然后,将样本暴露于CBCT以评估其单锥适应性.使用SPSS20、IBM、Armonk,NY,美利坚合众国。
    结果:拒绝了零假设,即在适应不同文件系统的单锥时不会有任何间隙区域。在旋转英雄塑形器文件系统(0.001mm2)中看到了最小的间隙面积,而在手工(HP)文件系统(0.015mm2)中看到了最大的间隙面积。
    结论:CBCT是检测弯曲管闭塞后间隙区域的有用工具。HP单锥适应显示最大间隙面积,旋转囊钳单锥适应显示最小间隙面积。
    OBJECTIVE: The aim of this study is to prepare and obturate the curved canals of the mesiobuccal root of maxillary first molar with four different file systems that is protaper hand files, rotary pro taper (RP) files, heroshaper hand files, and rotary hero shapers files and to evaluate the adaptation of their single-cone Gutta-percha by cone beam computed tomography (CBCT).
    METHODS: Eighty teeth were selected and were divided into two groups (G1A1, G1A2 and G2A1, G2A2 as hand and RP file system, G1A3, G1A4 and G2A3, G2A4 as hand and rotary hero shaper files system) of fourth teeth each. After access opening working length of the mesiobuccal canal was established. The distobuccal and palatal roots of the samples were removed using the diamond disc at the furcation level. \"Endoanalyser\" software was used to measure Schneider\'s angle on the preoperative radiograph. This angle was measured by drawing two lines-one parallel to the long axis of the canal, in the coronal third, and the second line from the apical foramen to intersect the point where the first line left the long axis of the canal. The canals of each group were then prepared according to the manufacturer\'s instructions for protaper hand files, RP files, heroshaper hand files, and rotary hero shapers files systems. Direct digital radiography image of all the samples was obtained. And then, the samples were exposed to CBCT to evaluate their single-cone adaptations. The data were analyzed using SPSS 20, IBM, Armonk, NY, United States of America.
    RESULTS: The null hypothesis that there will not be any gap area in the adaptation of their single-cone of different file system was rejected. Minimal gap area was seen in rotary hero shapers file system (0.001 mm2) and was maximum in hand protaper (HP) file system (0.015 mm2).
    CONCLUSIONS: CBCT is a useful tool in detecting the gap area after obturation in curved canals. The HP single-cone adaptation showed the maximum gap area and rotary heroshaper single-cone adaptation showed the minimum gap area.
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