gravity

重力
  • 文章类型: Journal Article
    有几种众所周知的医学状况,其中姿势和重力与自然史相互作用,包括怀孕。在这次审查中,我们全面概述了母亲体位与母亲生理和孕期休息时的病理生理之间的相互作用.我们对MEDLINE数据库进行了系统的文献检索,并确定了1991年至2021年的644项研究。符合我们的纳入标准。我们对由此产生的文献进行了叙述性回顾,并强调了差异,研究空白,和潜在的临床意义。我们按器官系统组织结果,从神经系统开始,通常沿颅尾方向进行我们的合成,用皮肤结束。循环系统值得我们最大和最密切的考虑-关于生理之间动态相互作用的文献(心率,每搏输出量,心输出量,血压,和全身血管阻力),病理生理学(例如,妊娠期高血压),和姿势的变化提供了一个复杂而迷人的例子,说明了这篇评论的主题的重要性。讨论的其他器官系统包括呼吸系统,肾,泌尿生殖系统,胃肠,腹部,和内分泌。除了总结有关母亲姿势-生理学相互作用的现有文献外,我们还指出了这方面进一步研究和临床发展的差距和机会。总的来说,我们的综述提供了产妇姿势-生理学相互作用的洞察力和相关性,相对于医疗保健的使命,以改善怀孕期间及以后的健康和健康。
    There are several well-known medical conditions in which posture and gravity interact with natural history, including pregnancy. In this review, we provide a comprehensive overview of interactions between maternal posture and maternal physiology and pathophysiology at rest during pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 644 studies from 1991 through 2021, inclusive, that met our inclusion criteria. We present a narrative review of the resulting literature and highlight discrepancies, research gaps, and potential clinical implications. We organize the results by organ system and, commencing with the neurological system, proceed in our synthesis generally in the craniocaudal direction, concluding with the skin. The circulatory system warranted our greatest and closest consideration-literature concerning the dynamic interplay between physiology (heart rate, stroke volume, cardiac output, blood pressure, and systemic vascular resistance), pathophysiology (e.g., hypertension in pregnancy), and postural changes provide an intricate and fascinating example of the importance of the subject of this review. Other organ systems discussed include respiratory, renal, genitourinary, gastrointestinal, abdominal, and endocrine. In addition to summarizing the existing literature on maternal posture-physiology interactions, we also point out gaps and opportunities for further research and clinical developments in this area. Overall, our review provides both insight into and relevance of maternal posture-physiology interactions vis à vis healthcare\'s mission to improve health and wellness during pregnancy and beyond.
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  • 文章类型: Journal Article
    我们模拟了万向节对准误差和旋转步长误差对三轴加速度计灵敏度矩阵和固有特性测量的影响。我们将研究限制为使用先前描述的测量和分析方案在双轴校准系统上进行的测量。以及校准系统中的缺陷,我们模拟了加速度计轴的不完美正交性和不同灵敏度的单独加速度计在一个完美的三轴加速度计,但我们留下了其他加速度计缺陷的表征,如非线性,以备将来研究。在这个框架内,灵敏度矩阵误差是由加速度计校准系统的构造和安装中的缺陷引起的,但不是因为模拟中包含的加速度计缺陷。由于测量系统中的缺陷,我们使用这项研究的结果将B型不确定性分配给灵敏度矩阵的组成部分和相关的固有特性。对于使用合理的制造和安装好的多轴旋转台进行校准,例如本文研究的,我们估计了1×10-5,2×10-5,5×10-5和2×10-4的标准不确定度的固有灵敏度的上限,灵敏度矩阵的对角元素,灵敏度矩阵的非对角元素,和零加速度偏移,分别相对于灵敏度矩阵元素为1,和5×10-3度的固有角度。
    We simulated the effects of gimbal-alignment errors and rotational step-size errors on measurements of the sensitivity matrix and intrinsic properties of a triaxial accelerometer. We restricted the study to measurements carried out on a two-axis calibration system using a previously described measurement and analysis protocol. As well as imperfections in the calibration system, we simulated imperfect orthogonality of the accelerometer axes and non-identical sensitivity of the individual accelerometers in an otherwise perfect triaxial accelerometer, but we left characterization of other accelerometer imperfections such as non-linearity for future study. Within this framework, sensitivity-matrix errors are caused by imperfections in the construction and installation of the accelerometer calibration system, but not by the accelerometer imperfections included in the simulations. We use the results of this study to assign type B uncertainties to the components of the sensitivity matrix and related intrinsic properties due to imperfections in the measurement system. For calibrations using a reasonably well manufactured and installed multi-axis rotation stage such as that studied in this paper, we estimated upper bounds to the standard uncertainties of the order of 1×10-5, 2×10-5, 5×10-5, and 2×10-4 for the intrinsic sensitivities, diagonal elements of the sensitivity matrix, off-diagonal elements of the sensitivity matrix, and zero-acceleration offsets, relative to a sensitivity-matrix element of 1, respectively, and 5×10-3 degrees for the intrinsic angles.
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  • 文章类型: Journal Article
    张力木(TW)是与被子植物树的引力相关的特殊木质部组织。然而,已经确定了很少的TW形成调节剂。支撑TW形成的分子机制仍然难以捉摸。这里,我们报道了一个类似胡杨KNOTTED的同源盒基因,PagKNAT2/6b,参与TW形成和重力响应。过表达PagKNAT2/6b的转基因杨树植物比对照显示出更敏感的引力性,如茎曲率增加所示。显微镜检查显示,在PagKNAT2/6b过表达系中,具有凝胶状细胞壁层(G层)和次生木质部不对称生长的纤维细胞更多。相反,PagKNAT2/6b显性抑制植物表现出TW形成减少和对重力刺激的反应降低。此外,对重力刺激的敏感性与发育阶段呈负相关。在PagKNAT2/6b转基因植物中,与生长和衰老相关的基因的表达受到影响。更重要的是,转录激活和电泳迁移率变化分析提示PagKNAT2/6b促进细胞分裂素代谢基因的表达。始终如一,细胞分裂素含量在PagKNAT2/6b过表达植物中增加。因此,PagKNAT2/6b参与引力和TW形成,可能通过调节细胞分裂素代谢。
    Tension wood is a specialized xylem tissue associated with gravitropism in angiosperm trees. However, few regulators of tension wood formation have been identified. The molecular mechanisms underpinning tension wood formation remain elusive. Here, we report that a Populus KNOTTED-like homeobox gene, PagKNAT2/6b, is involved in tension wood formation and gravity response. Transgenic poplar plants overexpressing PagKNAT2/6b displayed more sensitive gravitropism than controls, as indicated by increased stem curvature. Microscopic examination revealed greater abundance of fibre cells with a gelatinous cell wall layer (G-layer) and asymmetric growth of secondary xylem in PagKNAT2/6b overexpression lines. Conversely, PagKNAT2/6b dominant repression plants exhibited decreased tension wood formation and reduced response to gravity stimulation. Moreover, sensitivity to gravity stimulation showed a negative relationship with development stage. Expression of genes related to growth and senescence was affected in PagKNAT2/6b transgenic plants. More importantly, transcription activation and electrophoretic mobility shift assays suggested that PagKNAT2/6b promotes the expression of cytokinin metabolism genes. Consistently, cytokinin content was increased in PagKNAT2/6b overexpression plants. Therefore, PagKNAT2/6b is involved in gravitropism and tension wood formation, likely via modulation of cytokinin metabolism.
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  • 文章类型: Journal Article
    地面重力数据揭示了埃塞俄比亚主要裂谷地区活跃的火山和构造活动占主导地位的各种异常特征。在这样的地区,基于地面的数据收集仅限于现有道路,并且依赖于可访问的站点。这些导致了数据的差距,要么失踪,不均匀,或空间覆盖不足,必须使用适当的插值技术进行估计。对埃塞俄比亚中部主要裂谷的地面重力和高程数据进行了比较和评估,这些方法通常用于势场地球物理数据分析。在这项研究中,两种广泛使用的插值技术,最小曲率插值,和普通克里格法进行了比较和评估。采用了10%的保持验证,其中90%的数据点用于生成插值曲面,然后对剩余的10%进行评估。在使用每种技术进行插值之后,生成的网格被转换成离散的数据点(估计值)。然后将这些数据与现有的重力数据进行比较,它们被故意从网格化过程中排除(剩余10%的数据集)。通过均值、方差,平均绝对误差(MAE),均方根误差(RMSE),相关系数(r),和R平方。结果表明,普通的Kriging插值法在所有性能指标下都优于重力数据的最小曲率插值法,而对于高程数据集,这两种插值似乎都表现得同样好。因此,建议使用Kriging插值法进行埃塞俄比亚中部主要裂谷的势场重力研究。
    The ground-based gravity data reveals diverse anomaly signatures in areas of the Main Ethiopian rift where active volcanic and tectonic activities are dominant. In such a region ground-based data collection is restricted to existing roads and relies on accessible stations. These resulted in gaps in data, either missing, uneven, or insufficient spatial coverage that must be estimated with proper interpolation techniques. Comparison and evaluations of the spatial interpolation methods that are commonly used in potential field geophysical data analysis were made for the terrestrial gravity and elevation data of the central Main Ethiopian rift. In this research, two widely used interpolation techniques, minimum curvature interpolation, and Ordinary Kriging were compared and assessed. A 10 % hold-out validation was employed, where 90 % of the data points were used to generate interpolated surfaces, which were then evaluated against the remaining 10 %. Following interpolation with each technique, the generated grid was converted into discrete data points (estimated values). These are then compared with the available gravity data, which were deliberately excluded from the gridding process (10 % remaining dataset). The accuracy of each method was assessed by evaluation metrics such as mean value, variance, Mean Absolute Error (MAE), Root Mean Square Error (RMSE), correlation coefficient (r), and R-squared. The results showed that the ordinary Kriging interpolation method outperformed the minimum curvature interpolants for gravity data with all performance metrics, while both interpolants seem to perform equally well for the elevation dataset. Therefore, it is proposed to use the Kriging interpolation method for potential field gravity studies conducted in the central Main Ethiopia rift.
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  • 文章类型: Journal Article
    北部红海(NRS)被认为是导致裂谷系统的扩展大陆地区。重力和测深数据用于估算NRS区域下方岩石圈的Moho深度和弹性厚度Te,以表征其弯曲刚度并了解其力学行为。专注于NRS的MabahissDeep,我们分析了岩石圈的抗弯刚度。观测到的长波长正布格异常归因于地壳变薄和岩石圈地幔隆升。地壳厚度从沿海地区的28公里到轴向裂谷下方的24公里不等,支持区域补偿模型而不是艾里模型。正向建模表明,解释区域布格异常的最佳模型是Te等于7km的弯曲模型,表明大陆地壳脆弱且不规则。造成这种弱点的主要因素是加热活动。鉴于地壳的弱化状态和该地区的持续扩张,NRS裂痕可能会演变成破裂,有可能导致洋壳的形成.
    The northern Red Sea (NRS) is considered an extended continental region that has resulted in a rift system. Gravity and bathymetry data were used to estimate the Moho depth and the elastic thickness Te of the lithosphere beneath the NRS region to characterize its flexural rigidity and understand its mechanical behavior. Focusing on the Mabahiss Deep in NRS, we analyzed the lithosphere\'s flexural rigidity. The observed long-wavelength positive Bouguer anomaly is attributed to crustal thinning and lithospheric mantle uplift. The crustal thickness varies from 28 km in coastal areas to 24 km beneath the axial rift, supporting a regional compensation model over the Airy model. Forward modeling suggests that the optimal model explaining the regional Bouguer anomaly is a flexural model with Te equal to 7 km, indicating a weak and irregular continental crust. The primary factor contributing to this weakness is heating activity. Given the weakened state of the crust and the ongoing extension in the region, the NRS rift could evolve into a rupture, potentially leading to the formation of oceanic crust.
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  • 文章类型: Journal Article
    在他们的自然环境中,动物面临各种生态和社会挑战,这可能与不同认知技能的出现有关。为了评估认知技能的特定差异,我们用有蹄类动物作为研究模型,测试了5个不同物种的26个圈养个体(即,矮山羊,Capraaegagrushircus,美洲驼,格拉玛,guanacos,关尼科喇嘛,斑马,Equusgrevyi,还有犀牛,Dicerosbicornismichaeli)。跨物种,我们使用同样完善的实验程序来测试个人在幼稚物理任务中的表现,即对象持久性,短期空间记忆,因果关系,理解对象属性,和重力。我们的结果表明,研究对象表现出客体持久性,能够在60年代后记住隐藏食物的位置,并从摇动容器时产生或不产生的声音推断隐藏食物的位置。此外,他们展示了对基本对象属性的理解,能够根据遮挡物的大小和倾斜度定位隐藏在遮挡物后面的对象,并且可以可靠地跟踪不同条件下坠落物体的轨迹。最后,特定间的差异仅限于对对象属性的理解,并建议驯化物种作为山羊在需要这些技能的任务中可能比非驯化物种表现更好。这些结果为仍未研究的分类单元的认知技能提供了新信息,并确认有蹄类动物是认知进化比较研究的有前途的分类单元。
    In their natural environment, animals face a variety of ecological and social challenges, which might be linked to the emergence of different cognitive skills. To assess inter-specific variation in cognitive skills, we used ungulates as a study model, testing a total of 26 captive individuals across 5 different species (i.e., dwarf goats, Capra aegagrus hircus, llamas, Lama glama, guanacos, Lama guanicoe, zebras, Equus grevyi, and rhinos, Diceros bicornis michaeli). Across species, we used the same well-established experimental procedures to test individuals\' performance in naïve physics tasks, i.e. object permanence, short-term spatial memory, causality, understanding of object properties, and gravity. Our results revealed that study subjects showed object permanence, were able to remember the position of hidden food after up to 60 s, and inferred the position of hidden food from the sound produced or not produced when shaking containers. Moreover, they showed an understanding of basic object properties, being able to locate objects hidden behind occluders based on their size and inclination, and could reliably follow the trajectory of falling objects across different conditions. Finally, inter-specific differences were limited to the understanding of object properties, and suggest that domesticated species as goats might perform better than non-domesticated ones in tasks requiring these skills. These results provide new information on the cognitive skills of a still understudied taxon and confirm ungulates as a promising taxon for the comparative study of cognitive evolution.
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  • 文章类型: Journal Article
    在许多医疗条件下,包括怀孕,重力和姿势相互作用,影响生理学和病理生理学。最近的调查,例如,关于孕妇在妊娠中期的睡眠姿势以及对胎儿生长和死产风险的可能影响突出了该受试者的重要性和潜在的临床意义。在这次审查中,我们提供了广泛的讨论,从怀孕到产后期间,母亲的姿势对胎儿生理的影响。我们对MEDLINE数据库进行了系统的文献检索,并确定了1991年至2021年的242项研究,符合我们的纳入标准。在这里,我们提供了所得文献的合成。在回顾的第一部分,我们通过产妇休息姿势对子宫颈的影响对结果进行分组,子宫,胎盘,脐带,羊水,还有胎儿.在审查的第二部分,我们讨论了在各种产妇活动期间产妇姿势对胎儿相关结局的影响(例如,睡眠,工作,锻炼),医疗程序(例如,生育力,成像,手术),分娩和分娩。我们介绍已发表的文献,突出差距和差异,并建议未来的研究机会和临床实践的变化。总之,我们预计,这篇综述将揭示产妇姿势对胎儿生理的影响,从而为致力于改善产妇的研究人员和临床医生提供实用性,胎儿,和儿童健康。
    In numerous medical conditions, including pregnancy, gravity and posture interact to impact physiology and pathophysiology. Recent investigations, for example, pertaining to maternal sleeping posture during the third trimester and possible impact on fetal growth and stillbirth risk highlight the importance and potential clinical implications of the subject. In this review, we provide an extensive discussion of the impact of maternal posture on fetal physiology from conception to the postpartum period in human pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 242 studies from 1991 through 2021, inclusive, that met our inclusion criteria. Herein, we provide a synthesis of the resulting literature. In the first section of the review, we group the results by the impact of maternal posture at rest on the cervix, uterus, placenta, umbilical cord, amniotic fluid, and fetus. In the second section of the review, we address the impact on fetal-related outcomes of maternal posture during various maternal activities (e.g., sleep, work, exercise), medical procedures (e.g., fertility, imaging, surgery), and labor and birth. We present the published literature, highlight gaps and discrepancies, and suggest future research opportunities and clinical practice changes. In sum, we anticipate that this review will shed light on the impact of maternal posture on fetal physiology in a manner that lends utility to researchers and clinicians who are working to improve maternal, fetal, and child health.
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  • 文章类型: Journal Article
    我们提出了一种新的势场滤波方法,基于非常紧凑的解决方案对字段进行建模,即,预计源将占用源域中的最小允许体积。选定的解决方案,我们称之为“极其紧凑的源”(ECS)形成一种原子化模型,仍然满足重力和磁场的非唯一反问题。ECS模型不仅具有稀疏性,但也通过大的物理属性值(密度或磁化率)。模型的稀疏特性允许定义高度局部化的滤波器,这可以通过简单地指定要在给定区域中选择的原子来获得。此功能允许使用传统过滤器管理通常不可能的任务,例如分离具有相似波数内容的干扰异常。此外,该程序可以执行非常有效的区域/残余分离。我们在综合案例中演示了该方法,并将其应用于坎皮·弗莱格雷火山地区(意大利)的重力数据的真实案例中,我们使用ECS过滤来隔离奥利巴诺山穹顶的重力效应。
    We present a new filtering method for potential fields, based on modelling the fields in terms of very compact solutions, i.e., the sources are expected to occupy the smallest allowable volume in the source domain. The selected solutions, which we call \"Extremely Compact Sources\" (ECS) form a sort of atomized model, which still satisfies the non-unique inverse problem of gravity and magnetic fields. The ECS model is not only characterized by sparsity, but also by large values of the physical property (density or magnetic susceptibility). The sparse nature of the model allows for the definition of a highly localized filter, which can be obtained by simply specifying the atoms to be selected in a given area. This feature allows managing tasks normally impossible with traditional filters, such as the separation of interfering anomalies having a similar wavenumber content. In addition, the procedure can perform a very effective regional/residual separation. We demonstrate the method on synthetic cases and apply it in the real case of gravity data of Campi Flegrei volcanic area (Italy), where we use the ECS filtering to isolate the gravity effect of the Mount Olibano dome.
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  • 文章类型: Journal Article
    迁移的影响跨越各种社会维度,包括人口统计学,可持续性政治,经济,和性别差异。然而,移民选择目的地背后的决策过程仍然难以捉摸。现有模型主要依靠人口规模和旅行距离来解释迁移流的空间模式,忽略了显著的人口异质性。矛盾的是,移民经常长途跋涉,如果他们的侨民在这些地方,他们通常会前往较小的目的地。为了解决这个差距,我们提出了移民的侨民模型,结合强度(迁往一个国家的人数),和多样性(国内的目的地)。我们的模型只考虑目的地国家现有的侨民规模,影响移民选择特定住所的概率。尽管它简单,我们的模型准确地再现了观察到的奥地利(邮政编码级别)和美国大都市地区的稳定移民流动和分布,对不同地理尺度的移民流入进行精确估计。鉴于国际移民的增加,这项研究启发了我们对迁移流异质性的理解,帮助设计更具包容性,一体化城市。
    Migration\'s impact spans various social dimensions, including demography, sustainability, politics, economy, and gender disparities. Yet, the decision-making process behind migrants choosing their destination remains elusive. Existing models primarily rely on population size and travel distance to explain the spatial patterns of migration flows, overlooking significant population heterogeneities. Paradoxically, migrants often travel long distances and to smaller destinations if their diaspora is present in those locations. To address this gap, we propose the diaspora model of migration, incorporating intensity (the number of people moving to a country), and assortativity (the destination within the country). Our model considers only the existing diaspora sizes in the destination country, influencing the probability of migrants selecting a specific residence. Despite its simplicity, our model accurately reproduces the observed stable flow and distribution of migration in Austria (postal code level) and US metropolitan areas, yielding precise estimates of migrant inflow at various geographic scales. Given the increase in international migrations, this study enlightens our understanding of migration flow heterogeneities, helping design more inclusive, integrated cities.
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  • 文章类型: Journal Article
    围绕锂离子电池(LIB)的安全问题已引起越来越多的关注,因为它们有可能危及生命并造成重大的经济损失。然而,电池故障的起源是多种多样的,在制定安全措施以减轻意外灾难方面提出了重大挑战。在这项研究中,研究了LiNi0.5Co0.2Mn0.3O2||石墨基圆柱形18,650LIBs在室温下储存两年的老化机理。结果发现,电解质的不均匀分布可能是由重力引起的,导致电池内的温度变化。具体来说,观察到电池顶部的温度比底部的温度高约-0.89°C,与部分内部电阻的增加有关。此外,在拆卸和分析废电池后,观察到对电池顶部电极材料的最显著损坏。这些发现表明,重力引起的电解质不足会加剧副反应,特别是在电池的顶部。这项研究为长期和大规模应用中与高能量密度电池相关的安全问题提供了独特的视角。
    The safety concerns surrounding lithium-ion batteries (LIBs) have garnered increasing attention due to their potential to endanger lives and incur significant financial losses. However, the origins of battery failures are diverse, presenting significant challenges in developing safety measures to mitigate accidental catastrophes. In this study, the aging mechanism of LiNi0.5Co0.2Mn0.3O2||graphite-based cylindrical 18,650 LIBs stored at room temperature for two years was investigated. It was found that an uneven distribution of electrolytes can be caused by gravity, leading to temperature variations within the battery. Specifically, it was observed that the temperature at the top of the battery was approximately -0.89 °C higher than at the bottom, correlating with an increase in partial internal resistance. Additionally, upon disassembly and analysis of spent batteries, the most significant damage to electrode materials at the top of the battery was observed. These findings suggest that gravity-induced electrolyte insufficiency exacerbates side reactions, particularly at the top of the battery. This study offers a unique perspective on the safety concerns associated with high-energy-density batteries in long-term and large-scale applications.
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