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Various biomacromolecule components of extracellular matrix (ECM) link together to form a structurally stable composite. Monitoring of such matrix microstructure can be very important in studying structure-associated cellular processes, improving cellular function, and ensuring sufficient mechanical integrity in engineered tissues. This paper describes a novel method to study microscale alignment of matrix in engineered tissue scaffolds (ETS) that were usually composed of a variety of biomacromolecules derived by cells. as the organization of overall biomacromolecule network has been seldomly examined. First, a trained loading function was derived from Raman spectra of highly aligned native tissue via PCA, where prominent changes associated with Raman bands (e.g., 1444, 1465, 1605, 1627-1660 and 1665-1689 cm−1) were detected with respect to the polarized angle. These changes were mainly caused by the aligned matrix of many compounds within the tissue relative to the laser polarization, including proteins, lipids and carbohydrates. Hence this trained function was applied to quantify the alignment within ETS of various matrix components derived by cells. A simple metric called Amplitude Alignment Metric was derived to correlate the orientation dependence of polarized Raman spectra of ETS to the degree of matrix alignment. By acquiring polarized Raman spectra of ETS at micrometer regions, the Amplitude Alignment Metric was significantly higher in anisotropic ETS than isotropic ones. The PRS method showed a lower p-value for distinguishing the alignment between the two types of ETS as compared to the microscopic method for detecting fluorescently labeled protein matrices at similar microscopic scale. These results indicate the anisotropy of complex matrix in engineered tissue can be assessed at microscopic scale using a PRS-based simple metric, superior to traditional microscopic method. This PRS-based method can serve as a complementary tool for the design and assessment of engineered tissues that mimic the native matrix organizational microstructures. 

Spatial join is an important operation for combining spatial data. Parallelization is essential for improving spatial join performance. However, load imbalance due to data skew limits the scalability of parallel spatial join. There are many work sharing techniques to address this problem in a parallel environment. One of the techniques is to use data and space partitioning and then scheduling the partitions among threads/processes with the goal of minimizing workload differences across threads/processes. However, load imbalance still exists due to differences in join costs of different pairs of input geometries in the partitions. For the load imbalance problem, we have designed a work stealing spatial join system (WSSJ-DM) on a distributed memory environment. Work stealing is an approach for dynamic load balancing in which an idle processor steals computational tasks from other processors. This is the first work that uses work stealing concept (instead of work sharing) to parallelize spatial join computation on a large compute cluster. We have evaluated the scalability of the system on shared and distributed memory. Our experimental evaluation shows that work stealing is an effective strategy. We compared WSSJ-DM with work sharing implementations of spatial join on a high performance computing environment using partitioned and un-partitioned datasets. Static and dynamic load balancing approaches were used for comparison. We study the effect of memory affinity in work stealing operations involved in spatial join on a multi-core processor. WSSJ-DM performed spatial join using ST_Intersection on Lakes (8.4M polygons) and Parks (10M polygons) in 30 seconds using 35 compute nodes on a cluster (1260 CPU cores). A work sharing Master-Worker implementation took 160 seconds in contrast. 

Abstract Symmetric instability is a mechanism that can transfer geostrophic kinetic energy to overturning and dissipation. To date, symmetric instability has only been recognized to occur at the ocean surface or near topographic boundary layers. Analyses of direct microstructure measurements reveal enhanced dissipation caused by symmetric instability in the northwestern equatorial Pacific thermocline, which provides the first observational evidence of subsurface symmetric instability away from boundaries. Enhanced subsurface cross-equatorial exchange provides the negative potential vorticity needed to drive the symmetric instability, which is well reproduced by numerical modeling. These results suggest a new route to energy dissipation for large scale currents, and hence a new ocean turbulent mixing process in the ocean interior. Given the importance of vertical mixing in the evolution of equatorial thermocline, models may need to account for this mechanism to produce more reliable climate projections. 

Abstract Chemo-switchable catalytic [2+2+2] cycloaddition of alkenes with formaldimines is reported. Bis(tosylamido)methane (BTM) and 1,2-ditosyl-1,2-diazetidine (DTD), two bench-stable precursors for highly reactive tosylformaldimine, have been identified to be effective. BTM worked as a selective releaser of the formaldimine for catalytic [2+2+2] reactions toward hexahydropyrimidine products via a presumable ‘imine–alkene–imine’ addition. A unique catalytic retro-[2+2] reaction of DTD was used and has enabled a proposed ‘imine–alkene–alkene’ pathway with high chemoselectivity for the synthesis of 2,4-di­arylpiperidine derivatives. The two alternative processes are catalyzed by the simple and environmentally benign catalysts InCl3 and FeBr2, respectively. 

Abstract The structure and variations of the North Equatorial Counter Current (NECC) in the far western Pacific Ocean during 2014-2016 are investigated using repeated in-situ hydrographic data, altimeter data, Argo data, and reanalysis data. The NECC shifted ~1 degree southward and intensified significantly with its transport exceeding 40 Sv (1 Sv = 10 6 m 3 s -1 ), nearly double its climatology value, during the developing phase of the 2015/16 El Niño event. Observations show that the 2015/16 El Niño exerted a comparable impact on the NECC with that of the extreme 1997/98 El Niño in the far western Pacific Ocean. Baroclinic instability provided the primary energy source for the eddy kinetic energy (EKE) in the 2015/16 El Niño, which differs from the traditional understanding of the energy source of EKE as barotropic instability in low latitude ocean. The enhanced vertical shear and the reduced density jump between the NECC layer and the subsurface North Equatorial Subsurface Current (NESC) layer renders the NECC–NESC system baroclinically unstable in the western Pacific Ocean during El Niño developing phase. The eddy-mean flow interactions here are diverse associated with various states of the El Niño Southern Oscillation (ENSO).