Impaired drainage through capillary-venous networks contributes to age-related white matter loss
Andy Y. ShihStefan StamenkovićFranca SchmidNicolas WeitermannKevin TakasakiStephanie BonneyMaria J. SosaYuandong LiHannah BenettYongsoo KimJack Waters
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Abstract The gradual loss of cerebral white matter contributes to cognitive decline during aging. However, microvascular networks that support the metabolic demands of white matter remain poorly defined. We used in vivo deep multi-photon imaging to characterize microvascular networks that perfuse cortical layer 6 and corpus callosum, a highly studied region of white matter in the mouse brain. We show that these deep tissues are exclusively drained by sparse and wide-reaching venules, termed principal cortical venules, which mirror vascular architecture at the human cortical-U fiber interface. During aging, capillary networks draining into deep branches of principal cortical venules are selectively constricted, reduced in density, and diminished in pericyte numbers. This causes hypo-perfusion in deep tissues, and correlates with gliosis and demyelination, whereas superficial tissues become relatively hyper-perfused. Thus, age-related impairment of capillary-venular drainage is a key vascular deficit that contributes to the unique vulnerability of cerebral white matter during brain aging.Keywords:
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Practical experience has shown that existing method of drainage determination, such as Freeness, can result in poor correlation with forming section performance. The G/W Drainage-Retention Tester is an instrument intended to monitor the entire drainage pattern to better predict furnish behavior on a paper machine.The studies were conducted to evaluate the GWDRT and results showed that the GWDRT can be used to study the entire drainage profile of a furnish. Data collected can be used to determine and compare pulp characteristics in terms of free drainage, overall drainage, retention, solids levels, and formation. Rather than evaluate and report drainage with a single number, the GWDRT has the ability to provide data which distinguishes between free drainage and overall drainage. Experience has also shown that GWDRT can detect differences in the drainage characteristics of different pulps that conventional CSF Freeness Testers were unable to detect. These features make the GWDRT an invaluable tool for both mill control and research purposes.
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Study has been conducted in 188 ha block at Segwa drainage pilot area to assess the impact of drainage on the removal of salts from the area. Pre drainage estimations were done to quantify the total salts deposited during 1996-97. Later post drainage estimation of salts left out during the year 1999-2000 was done based on field measurements. Equations on salt and water balance were formulated separately for pre and post drainage depending upon the available data. From the study, it was observed that during pre-drainage period about 7 t/ha of salts remained as balance, whereas during post drainage period about 4.7 t/ha of salts remained as balance. Moreover this was the condition when only II % of the pilot area was brought under drainage.
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Journal Article Comments: White on Black among The Mormons: A Critique of White & White Get access Armand L. Mauss Armand L. Mauss Washington State University Search for other works by this author on: Oxford Academic Google Scholar Sociology of Religion, Volume 42, Issue 3, Fall 1981, Pages 277–282, https://doi.org/10.2307/3711039 Published: 01 October 1981
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최근 도로 비탈면에 설치되는 도수로 집수정의 미설치 혹은 배수능력 부족에 의한 월류로 인하여 도로 침수피해가 많이 발생하고 있다. 따라서 비탈을 따라 흐르는 우수를 배제하는 도수로 집수정의 역할은 매우 중요하다. 그러나 도수로 집수정의 설계 및 설치기준이 불분명하여 시공시 현장여건에 따라 설치되고 있는 실정이다. 그러므로 비탈면 배수시설의 배수능력을 증대시킬 수 있는 설치방안을 제시하기 위하여 도수로 집수정의 흐름특성 분석이 필요하다. 본 연구에서는 도수로 집수정의 흐름특성을 분석하고 집수정의 배수능력을 증대시키기 위한 구체적인 설치기준을 제시하기 위하여 수리실험 연구를 수행하였다. 선정된 실험조건에 따라 표준 도수로 집수정 크기의 1/4 축소 수리모형을 제작하였다. 도수로 측구와 집수정의 접합각과 접합위치 및 집수정과 배수관거의 접합 높이 등을 변화시키면서 수리실험을 실시하였다. 수리실험 결과 도수로는 집수정 높이(h)의 1/3h 지점에 접합시키고 배수 관거는 집수정 바닥으로부터 연결관거의 직경(D)의 0.3D 지점에 접합하는 경우에 집수정에서의 배수효율이 증가하였다. Recently, inundation damage of road was seriously occurred without drainage well or overflow due to lack of drainage capacity at drainage well installed on the slopes. The drainage well has a very important role in the rainfall drainage from the slopes. However, drainage well of waterway was installed in accordance with the site conditions during construction because the design and installation criteria of drainage well were unclear. Therefore, it is necessary to analyze flow characteristics and drainage capacity at drainage well of waterway for improvement of the design criteria. In this study, hydraulic experiment was conducted to analyze the flow characteristics and enact standard design criteria of drainage well. Hydraulic experimental apparatus(1/4 reduction model) which can change the slope of waterway and the joining heights of waterway and drain pipe were installed to analyze of flow characteristics at the drainage well. The drainage efficiency of the drainage well was increased when the waterway was connected at the 1/3h of the drainage well and the drain pipe was joined at the 0.3D of the drainage well.
Well drainage
Drainage system (geomorphology)
Watertable control
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Abstract According to data collected from a field experiment of controlled drainage in Yinnan Irrigation District, this paper analyses the amount of drainage water and variation of salt and water balance. Compared with traditional drainage, it is found that the volume of drainage water is obviously reduced by controlled drainage. The groundwater table in the controlled drainage areas is 1.8 cm higher than that in the traditional drainage areas. If drainage velocity is used to substitute for the volume of drainage water, the total volume of drainage water drained from controlled drainage areas is on average 50% less than that from traditional drainage areas. At the same time, the volume of underground drainage water decreases by 46%. By analysing the balance between salt and water in the controlled drainage areas, the introduced amount of salt is less than the discharged amount of salt, so salt and water are still kept in good status. Copyright © 2008 John Wiley & Sons, Ltd.
Well drainage
Watertable control
Soil salinity control
Water balance
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The importance of macrostructural white matter changes, including white matter lesions and atrophy, in intact brain functioning is increasingly being recognized. Diffusion tensor imaging (DTI) enables measurement of the microstructural integrity of white matter. Loss of white matter integrity in aging has been reported, but whether this is inherent to the aging process itself or results from specific white matter pathology is unknown. In 832 persons aged 60 years and older from the population-based Rotterdam Study, we measured fractional anisotropy (FA) and directional diffusivities in normal-appearing white matter using DTI. All subjects' DTI measures were projected onto a common white matter skeleton to enable robust voxelwise comparison. With increasing age, multiple regions showed significant decreases in FA or increases in axial or radial diffusivity in normal-appearing white matter. However, nearly all of these regional changes were explained by either white matter atrophy or by white matter lesions; each of which related to changes in distinct brain regions. These results indicate that loss of white matter integrity in aging is primarily explained by atrophy and lesion formation and not by the aging process itself. Furthermore, white matter atrophy and white matter lesion formation relate to loss of integrity in distinct brain regions, indicating the two processes are pathophysiologically different. PMID: 18755279
Structural integrity
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Grey matter
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Drainage system (geomorphology)
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The effects of drainage well work, a construction method used to prevent landslides, were studied and the following results obtained.(1) To understand the groundwater drainage effects of installing a drainage well on a sloping slide area, it is necessary to study the drainage caused by the drainage boring in addition to the drainage caused by the drainage well itself.(2) The study confirmed that after installing a drainage well, the groundwater level is low close to the drainage well but rises as the distance from the drainage well increases.(3) The overall decline in the ground water level accompanying the construction of the drainage well can be found using formula (1).(4) The decline in the ground water level accompanying the construction of the drainage well is limited to the area where drainage boring has been performed.
Well drainage
Watertable control
Drainage system (geomorphology)
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