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Path planning for a point-mass robot moving in a cluttered two-dimensional environment is a well studied but non-trivial problem. In this paper we propose a novel computationally efficient and resolution-complete path generation method based on electrostatics. The proposed scheme comprises two stages. First, an auxiliary electrostatic problem is formulated where the boundary conditions of the Laplace equation are specified based on the map of the original path planning problem and is solved to obtain a map-specific electrostatic potential. Second, feasible paths are constructed by following any equipotential curve whose potential value is different from those of obstacles and boundaries. The electrostatic potential in the proposed method differs from the celebrated repulsive/attractive force-based potential field by its non-vanishing gradient, based on which the resolution-completeness is established. The computational efficiency of the proposed method arises from a novel electrostatic solver based on complex analysis, and on an original collision-checking algorithm inspired by the Residue theorem. Extensive numerical examples are provided to demonstrate the effectiveness and limitations of the proposed method. We believe this work provides an unconventional strategy for quantitatively encoding global map information and can play a role complementary to prevailing path planning methods.

Summary: Germline alterations of the NF2 gene cause neurofibromatosis type 2, a syndrome manifested with benign tumors, and Nf2 deletion in mice also results in slow tumorigenesis. As a regulator of the Hippo signaling pathway, NF2 induces LATS1/2 kinases and consequently represses YAP/TAZ. YAP/TAZ oncoproteins are also inhibited by motin family proteins (Motins). Here, we show that the Hippo signaling is fine-tuned by Motins in a NF2-dependent manner, in which NF2 recruits E3 ligase RNF146 to facilitate ubiquitination and subsequent degradation of Motins. In the absence of NF2, Motins robustly accumulate to restrict full activation of YAP/TAZ and prevent rapid tumorigenesis. Hence, NF2 deficiency not only activates YAP/TAZ by inhibiting LATS1/2 but also stabilizes Motins to keep YAP/TAZ activity in check. The upregulation of Motins upon NF2 deletion serves as a strategy for avoiding uncontrolled perturbation of the Hippo signaling and may contribute to the benign nature of most NF2-mutated tumors.

Mutations in the enzyme isocitrate dehydrogenase 1/2 (IDH1/2) are the most common somatic mutations in low-grade glioma (LGG). The Hippo signaling pathway is known to play a key role in organ size control, and its dysregulation is involved in the development of diverse cancers. Large tumor suppressor 1/2 (LATS1/2) are core Hippo pathway components that phosphorylate and inactivate Yes-associated protein (YAP), a transcriptional co-activator that regulates expression of genes involved in tumorigenesis. A recent report from The Cancer Genome Atlas (TCGA) has highlighted a frequent hypermethylation of LATS2 in IDH-mutant LGG. However, it is unclear if LATS2 hypermethylation is associated with YAP activation and prognosis of LGG patients. Here, we performed a network analysis of the status of the Hippo pathway in IDH-mutant LGG samples and determined its association with cancer prognosis. Combining TCGA data with our biochemical assays, we found hypermethylation of LATS2 promoter in IDH-mutant LGG. LATS2 hypermethylation, however, did not translate into YAP activation but highly correlated with IDH mutation. LATS2 hypermethylation may thus serve as an alternative for IDH mutation in diagnosis and a favorable prognostic factor for LGG patients.

Flexible polyurethane (PU) foams with varying polyethylene fiber contents were synthesized to improve their acoustic performances. The purpose of this study was to investigate the effects of different polyethylene fiber contents of the PU foams on the resultant sound absorption, which was characterized by the impedance tube technique to obtain the incident sound absorption coefficient. Other parameters related to acoustic absorption performance of polyurethane foams were also measured such as microstructure, porosity and airflow resistivity. In this paper, these parameters were analyzed and compared with those of pure polyurethane foam. The results showed that the acoustic absorption properties of the PU foams were improved especially in the low frequency region by adding polyethylene fiber. When 0.2 g polyethylene fiber was added into the PU foam composite, the sound absorption coefficient is best especially around 125 – 315 Hz. The maximum enhancement in the acoustic properties of the PU foams was obtained by adding 0.1 g polyethylene fiber.