An Alternative Scanning Strategy to Detect Faces

The sliding window approach is the most widely used technique to detect faces in an image. Usually a classifier is applied on a regular grid and to speed up the scanning, the grid spacing is increased, which increases the number of miss detections. In this paper we propose an alternative scanning method which minimizes the number of misses, while improving the speed of detection. To achieve this we use an additional classifier that predicts the bounding box of a face within a local search area. Then a face/non-face classifier is used to verify the presence or absence of a face. We propose a new combination of binary features which we term as u-Ferns for bounding box estimation, which performs comparable or better than former techniques. Experimental evaluation on benchmark database show that we can achieve 15-30% improvement in detection rate or speed when compared to the standard scanning technique

Targeted Disruption of Ephrin B1 in Cells of Myeloid Lineage Increases Osteoclast Differentiation and Bone Resorption in Mice

Disruption of ephrin B1 in collagen I producing cells in mice results in severe skull defects and reduced bone formation. Because ephrin B1 is also expressed during osteoclast differentiation and because little is known on the role of ephrin B1 reverse signaling in bone resorption, we examined the bone phenotypes in ephrin B1 conditional knockout mice, and studied the function of ephrin B1 reverse signaling on osteoclast differentiation and resorptive activity. Targeted deletion of ephrin B1 gene in myeloid lineage cells resulted in reduced trabecular bone volume, trabecular number and trabecular thickness caused by increased TRAP positive osteoclasts and bone resorption. Histomorphometric analyses found bone formation parameters were not changed in ephrin B1 knockout mice. Treatment of wild-type precursors with clustered soluble EphB2-Fc inhibited RANKL induced formation of multinucleated osteoclasts, and bone resorption pits. The same treatment of ephrin B1 deficient precursors had little effect on osteoclast differentiation and pit formation. Similarly, activation of ephrin B1 reverse signaling by EphB2-Fc treatment led to inhibition of TRAP, cathepsin K and NFATc1 mRNA expression in osteoclasts derived from wild-type mice but not conditional knockout mice. Immunoprecipitation with NHERF1 antibody revealed ephrin B1 interacted with NHERF1 in differentiated osteoclasts. Treatment of osteoclasts with exogenous EphB2-Fc resulted in reduced phosphorylation of ezrin/radixin/moesin. We conclude that myeloid lineage produced ephrin B1 is a negative regulator of bone resorption in vivo, and that activation of ephrin B1 reverse signaling inhibits osteoclast differentiation in vitro in part via a mechanism that involves inhibition of NFATc1 expression and modulation of phosphorylation status of ezrin/radixin/moesin

Structure of RapA, a Swi2/Snf2 Protein that Recycles RNA Polymerase During Transcription

SummaryRapA, as abundant as σ70 in the cell, is an RNA polymerase (RNAP)-associated Swi2/Snf2 protein with ATPase activity. It stimulates RNAP recycling during transcription. We report a structure of RapA that is also a full-length structure for the entire Swi2/Snf2 family. RapA contains seven domains, two of which exhibit novel protein folds. Our model of RapA in complex with ATP and double-stranded DNA (dsDNA) suggests that RapA may bind to and translocate on dsDNA. Our kinetic template-switching assay shows that RapA facilitates the release of sequestered RNAP from a posttranscrption/posttermination complex for transcription reinitiation. Our in vitro competition experiment indicates that RapA binds to core RNAP only but is readily displaceable by σ70. RapA is likely another general transcription factor, the structure of which provides a framework for future studies of this bacterial Swi2/Snf2 protein and its important roles in RNAP recycling during transcription

LRRK1 regulation of actin assembly in osteoclasts involves serine 5 phosphorylation of L-plastin

Mice with disruption of Lrrk1 and patients with nonfunctional mutant Lrrk1 exhibit severe osteopetrosis phenotypes because of osteoclast cytoskeletal dysfunction. To understand how Lrrk1 regulates osteoclast function by modulating cytoskeleton rearrangement, we examined the proteins that are differentially phosphorylated in wild-type mice and Lrrk1-deficient osteoclasts by metal affinity purification coupled liquid chromatography/mass spectrometry (LC/MS) analyses. One of the candidates that we identified by LC/MS is L-plastin, an actin bundling protein. We found that phosphorylation of L-plastin at serine (Ser) residues 5 was present in wild-type osteoclasts but not in Lrrk1-deficient cells. Western blot analyses with antibodies specific for Ser5 phosphorylated L-plastin confirmed the reduced L-plastin Ser5 phosphorylation in Lrrk1 knockout (KO) osteoclasts. micro computed tomography (Micro-CT) analyses revealed that the trabecular bone volume of the distal femur was increased by 27% in the 16 to 21-week-old L-plastin KO females as compared with the wild-type control mice. The ratio of bone volume to tissue volume and connectivity density were increased by 44% and 47% (both P \u3c 0.05), respectively, in L-plastin KO mice. Our data suggest that targeted disruption of L-plastin increases trabecular bone volume, and phosphorylation of Ser5 in L-plastin in the Lrrk1 signaling pathway may in part contribute to actin assembly in mature osteoclasts

Effect of Langmuir monolayer of bovine serum albumin protein on the morphology of calcium carbonate

Bovine serum albumin (BSA) Langmuir monolayer, as a model of biomineralization-associated proteins, was used to study its effect on regulated biomineralization of calcium carbonate. The effects of the BSA Langmuir monolayer and the concentration of the subphase solution on the nucleation and growth processes and morphology of the calcium carbonate crystal were investigated. The morphology and polymorphic phase of the resulting calcium carbonate crystals were characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Moreover, the interaction mechanisms of the subphase solution with the BSA Langmuir monolayer were discussed. It was found that BSA Langmuir monolayer could be used as a template to successfully manipulate the polymorphic phase and crystal morphology of calcium carbonate and had obvious influence on the oriented crystallization and growth. The final morphology or aggregation mode of the calcite crystal was closely dependent on the concentration of calcium bicarbonate solution. It is expected that this research would help to better understand the mechanism of biomineralization by revealing the interactions between protein matrices and crystallization of calcium carbonate crystal.Comment: 4 pages, 4 figure

Low‐Field Actuating Magnetic Elastomer Membranes Characterized using Fibre‐Optic Interferometry

Smart robotic devices remotely powered by magnetic field have emerged as versatile tools for wide biomedical applications. Soft magnetic elastomer (ME) composite membranes with high flexibility and responsiveness are frequently incorporated to enable local actuation for wireless sensing or cargo delivery. However, the fabrication of thin ME membranes with good control in geometry and uniformity remains challenging, as well as the optimization of their actuating performances under low fields (milli‐Tesla). In this work, the development of ME membranes comprising of low‐cost magnetic powder and highly soft elastomer through a simple template‐assisted doctor blading approach, is reported. The fabricated ME membranes are controllable in size (up to centimetre‐scale), thickness (tens of microns) and high particle loading (up to 70 wt.%). Conflicting trade‐off effects of particle concentration upon magnetic responsiveness and mechanical stiffness are investigated and found to be balanced off as it exceeds 60 wt.%. A highly sensitive fibre‐optic interferometric sensing system and a customized fibre‐ferrule‐membrane probe are first proposed to enable dynamic actuation and real‐time displacement characterization. Free‐standing ME membranes are magnetically excited under low field down to 2 mT, and optically monitored with nanometer accuracy. The fast and consistent responses of ME membranes showcase their promising biomedical applications in nanoscale actuation and sensing