attenuation

衰减
  • 文章类型: Journal Article
    To quantitate the degradation rate of 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-[g]-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) under field conditions, a level III fugacity model combined with a least-squares method was used to determine the degradation rate of HHCB and AHTN in the North Canal River watershed of Beijing, China. Model fitting, validation, sensitivity, and uncertainty analyses revealed that the established model was stable and robust. The degradation rates of HHCB and AHTN were 4.16 × 10-3 h-1 (t1/2 = 167 h) and 1.68 × 10-2 h-1 (t1/2 = 41.3 h), respectively. The calculated degradation rates were extrapolated to the Liangshui River, and indicated that the differences between the measured and predicted concentrations were less than 0.32 and 0.34 log units for HHCB and AHTN, respectively. The attenuation rates of HHCB and AHTN were calculated, and the results indicated that degradation was an important yet not the sole contributor to the degradation of the polycyclic musks. Results of uncertainty analyses indicated that the inflow and outflow concentrations of the polycyclic musks in the surface water of each segment strongly influenced the model outputs, followed by environmental factors (water depth and flow rate). It is essential to measure the degradation rate in the field because of the influence of the surrounding environment. The present study reveals the utility of fugacity models to quantify the degradation rate of organic micropollutants in the field.
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  • 文章类型: Journal Article
    本研究的目的是评估在胸部计算机断层扫描血管造影(T-CTA)期间,静脉通路(IVA)部位的选择是否会影响主动脉衰减以及静脉装置放置的任何相关风险。
    对2013年1月1日至2015年8月14日之间进行的所有T-CTA检查进行回顾性审查,以确定通过替代(即非肘部)IVA(n=1769)进行造影剂注射的检查。使用时间匹配,选择肘前IVA检查(n=1769)作为对照。每次考试,在升主动脉中测量衰减。随后从纳入本研究的所有3538名患者收集患者和技术数据。使用多元线性回归来确定IVA部位是否影响衰减。最后,我们收集并比较了整个T-CTA队列的外渗相关数据.
    手/手腕,手臂,在衰减方面,中心静脉接入装置IVA均等同于肘前IVA(分别为P=0.579,P=0.599和P=0.522)。前臂和骨内IVA的衰减明显高于肘前IVA(分别为P=0.010和P=0.002)。与左侧IVA相比,右侧IVA与11Hounsfield单位的小衰减增加相关(P<0.001)。在外渗方面,肘前IVA相当于手/手腕,前臂,上臂IVA(P=0.778,P=0.060,P=0.090)。
    对于T-CTA成像,使用非肘前IVA实现的令人满意的主动脉衰减等同于使用肘前IVA实现的衰减。外周IVA装置造影剂外渗的风险相对较低,然而,适当的IVA部位选择应被视为未来成像研究成功使用造影剂的重要因素.当在经历造影剂的压力注射的高弯曲/移动范围的区域中使用外围IV装置时,这防止通过可预防的装置故障对患者造成不适当的伤害。
    UNASSIGNED: The objective of this study was to evaluate whether the choice of intravenous access (IVA) site affects aortic attenuation during thoracic computed tomographic angiography (T-CTA) and any associated risks with intravenous device placement.
    UNASSIGNED: All T-CTA exams performed between 1/1/2013 and 8/14/2015 were retrospectively reviewed to identify those performed with contrast media injection via alternative (i.e. non-antecubital) IVA (n = 1769). Using time matching, antecubital IVA exams (n = 1769) were selected as controls. For each exam, attenuation was measured in the ascending aorta. Patient and technical data was subsequently collected from all 3538 patients included in this study. Multiple linear regression was used to determine if IVA site affected attenuation. Lastly, data related to extravasations for the entire T-CTA cohort were collected and compared.
    UNASSIGNED: Hand/wrist, arm, and central venous access device IVA were all equivalent to antecubital IVA in terms of attenuation (P = 0.579, P = 0.599, and P = 0.522 respectively). Forearm and intraosseous IVA had significantly higher attenuation (P = 0.010 and P = 0.002, respectively) than antecubital IVA. Right-sided IVA was associated with a small attenuation increase of 11 Hounsfield Units (P < 0.001) compared to left-sided IVA. In terms of extravasation, antecubital IVA was equivalent to hand/wrist, forearm, and upper arm IVA (P = 0.778, P = 0.060, and P = 0.090 respectively).
    UNASSIGNED: Satisfactory aortic attenuation achieved with non-antecubital IVA is equivalent to attenuation achieved with antecubital IVA for T-CTA imaging. The risk of contrast media extravasation in peripheral IVA devices was relatively low, however, appropriate IVA site selection should be considered an important factor for successful administration of contrast media for future imaging studies. This prevents undue harm to patients through preventable device failures when using a peripheral IV device in areas of high flexion/range of movements undergoing pressure injection for contrast media.
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  • 文章类型: Case Reports
    BACKGROUND: While some traumatic closed index extensor tendon ruptures at the musclotendinous junction have been previously reported, closed index extensor tendon pseudorupture due to intertendinous attenuation is exceedingly rare with only one case report of a gymnastics-related sports injury in the English literature. Herein, we report two non-sports injury related cases of traumatic index extensor tendon attenuation mimicking closed tendon rupture, including the pathological findings and intraoperative video of the attenuated extensor indicis proprius tendon.
    METHODS: A 28-year-old man and a 30-year-old man caught their hands in a high-speed drill and lathe, respectively, which caused a sudden forced flexion of their wrists. They could not actively extend the metacarpophalangeal joints of their index fingers. Intraoperatively, although the extensor indicis proprius and index extensor digitorum communes tendons were in continuity without ruptures, both tendons were attenuated and stretched. The attenuated index extensor tendons were reconstructed either with shortening by plication or step-cut when the tendon damage was less severe or, in severely attenuated tendons, with tendon grafting (ipsilateral palmaris longus) or tendon transfer. Six months after the operation, the active extension of the index metacarpophalangeal joints had recovered well.
    CONCLUSIONS: Two cases of traumatic index extensor tendon attenuation were treated successfully by shortening the attenuated tendon in combination with tendon graft or transfer. We recommend WALANT (wide-awake local anesthesia and no tourniquet) in the reconstruction surgery of index extensor tendon attenuation to determine the appropriate amount of tendon shortening or optimal tension for tendon grafting or transfer. Intraoperative voluntary finger movement is essential, as it is otherwise difficult to judge the stretch length of intratendinous elongation and extent of traumatic intramuscular damage affecting tendon excursion.
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  • 文章类型: Journal Article
    Camelpox病毒是Camelpox的病原体,骆驼的一种高度传染性疾病。先前已经报道了一种高传代的骆驼痘病毒株含有几种更类似于牛痘的基因,一种没有已知天然宿主的病毒,涵盖各种菌株,显示高菌株间基因组变异。在这项研究中,我们证明了另一个高通道,减毒活疫苗,包含一种不同的骆驼痘病毒株,含有与不同的痘苗病毒株相匹配的基因组序列。这些结果是在提出的假设的背景下讨论的,以解释未知的牛痘病毒的起源,建议进一步研究通过传代阐明正痘病毒的进化轨迹。
    Camelpox virus is the causative agent of Camelpox, a highly contagious disease of camels. A high passage Camelpox virus strain has previously been reported to contain several genes which more closely resemble Vaccinia, a virus species with no known natural host, encompassing various strains that show high inter-strain genomic variation. In this study, we demonstrate that yet another high passage, live attenuated vaccine, comprising a different strain of Camelpox virus, contains genomic sequences that match a differing strain of Vaccinia virus. These results are discussed in the context of hypotheses put forward to explain the unknown origins of Vaccinia virus, suggesting further studies to elucidate evolutionary trajectories of Orthopoxviruses through passaging.
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  • 文章类型: Journal Article
    Measurement error in exposure variables is a serious impediment in epidemiological studies that relate exposures to health outcomes. In nutritional studies, interest could be in the association between long-term dietary intake and disease occurrence. Long-term intake is usually assessed with food frequency questionnaire (FFQ), which is prone to recall bias. Measurement error in FFQ-reported intakes leads to bias in parameter estimate that quantifies the association. To adjust for bias in the association, a calibration study is required to obtain unbiased intake measurements using a short-term instrument such as 24-hour recall (24HR). The 24HR intakes are used as response in regression calibration to adjust for bias in the association. For foods not consumed daily, 24HR-reported intakes are usually characterized by excess zeroes, right skewness, and heteroscedasticity posing serious challenge in regression calibration modeling. We proposed a zero-augmented calibration model to adjust for measurement error in reported intake, while handling excess zeroes, skewness, and heteroscedasticity simultaneously without transforming 24HR intake values. We compared the proposed calibration method with the standard method and with methods that ignore measurement error by estimating long-term intake with 24HR and FFQ-reported intakes. The comparison was done in real and simulated datasets. With the 24HR, the mean increase in mercury level per ounce fish intake was about 0.4; with the FFQ intake, the increase was about 1.2. With both calibration methods, the mean increase was about 2.0. Similar trend was observed in the simulation study. In conclusion, the proposed calibration method performs at least as good as the standard method.
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  • 文章类型: Case Reports
    混合肾肿瘤(HRT)是罕见的肿瘤,包含良性和恶性成分。含有高度恶性病理的散发性孤立性HRT似乎极为罕见[1]。我们描述了我们机构中的一例肿瘤,该肿瘤的特征为2型乳头状RCC和非典型嗜酸细胞瘤混合瘤,在非对比计算机断层扫描中模仿了简单的囊肿。
    Hybrid renal tumors (HRT) are rare neoplasms that contain both benign and malignant components. Sporadic solitary HRT that contain high-grade malignant pathology appear to be extremely rare [1]. We describe a case at our institution of a tumor that was characterized as a type-2 papillary RCC and atypical oncocytoma hybrid that mimicked a simple cyst on non-contrast computed tomography.
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