Sparse Higher Order ?ech Filtrations

For a finite set of balls of radius r, the k-fold cover is the space covered by at least k balls. Fixing the ball centers and varying the radius, we obtain a nested sequence of spaces that is called the k-fold filtration of the centers. For k = 1, the construction is the union-of-balls filtration that is popular in topological data analysis. For larger k, it yields a cleaner shape reconstruction in the presence of outliers. We contribute a sparsification algorithm to approximate the topology of the k-fold filtration. Our method is a combination and adaptation of several techniques from the well-studied case k = 1, resulting in a sparsification of linear size that can be computed in expected near-linear time with respect to the number of input points

Palladin is Upregulated in Kidney Disease and Contributes to Epithelial Cell Migration After Injury

Recovery from acute kidney injury involving tubular epithelial cells requires proliferation and migration of healthy cells to the area of injury. In this study, we show that palladin, a previously characterized cytoskeletal protein, is upregulated in injured tubules and suggest that one of its functions during repair is to facilitate migration of remaining cells to the affected site. In a mouse model of anti-neutrophilic cytoplasmic antibody involving both tubular and glomerular disease, palladin is upregulated in injured tubular cells, crescents and capillary cells with angiitis. In human biopsies of kidneys from patients with other kidney diseases, palladin is also upregulated in crescents and injured tubules. In LLC-PK1 cells, a porcine proximal tubule cell line, stress induced by transforming growth factor-β1 (TGF-β1) leads to palladin upregulation. Knockdown of palladin in LLC-PK1 does not disrupt cell morphology but does lead to a defect in cell migration. Furthermore, TGF-β1 induced increase in the 75 kDa palladin isoform occurs in both the nucleus and the cytoplasm. These data suggest that palladin expression is induced in injured cells and contributes to proper migration of cells in proximal tubules, possibly by regulation of gene expression as part of the healing process after acute injury

Sub-Saharan Africa's Mothers, Newborns, and Children: Where and Why Do They Die?

In the first article in a series on maternal, newborn, and child health in sub-Saharan Africa, Joy Lawn and colleagues outline where and why deaths among mothers and children occur and what known interventions can be employed to prevent these deaths

A roadmap for planetary caves science and exploration

2 páginas.- 1 figura.- 16 referenciasTo the Editor — 2021 is the International Year of Caves and Karst. To honour this occasion, we wish to emphasize the vast potential embodied in planetary subsurfaces. While researchers have pondered the possibility of extraterrestrial caves for more than 50 years, we have now entered the incipient phase of planetary caves exploration....Peer reviewe