Seeing a Better World from Space

Understanding change is essential to addressing our most pressing global challenges. Organizations need actionable insight to make critical decisions that affect communities, economies, and national security. As a global leader of advanced geospatial and space-based technology solutions, Maxar has an unprecedented ability to observe, analyze, and monitor these global changes. In this talk, I’ll discuss the cutting-edge research, technological capabilities, and imagery products and analytics we develop at Maxar to unlock the power of geospatial data to understand and navigate our changing world

The framework for satellite gravity data assimilation into land surface models

The Gravity Recovery and Climate Experiment (GRACE) mission has provided an unprecedented global, homogeneous observational dataset of the time variation in terrestrial water storage (TWS) since 2002. This product has seen widespread use in the study of processes in hydrology, oceanography, the cryosphere, and is particularly critical to inform, improve, and validate computational models of the Earth system. Assimilation of the GRACE TWS fields into current land surface models can correct model deficiencies due to errors in the model structure, atmospheric forcing datasets, parameters, etc. However, the assimilation process is complicated by spatial and temporal resolution discrepancies between the model and observational datasets, characterization of the error in each, and requires tuning to the unique characteristics of satellite gravity data. This study establishes a framework for hydrological data assimilation of terrestrial water storage data from GRACE, closes the loop between GRACE product development and its scientific use, and analyzes the assimilated results for use with current GRACE products and future satellite gravity missions. The framework fuses the strengths of the observational and land surface model datasets into an assimilated product representative of the signal strength and large scale structures of the GRACE dataset effectively downscaled to the high resolution land surface dynamics. The data assimilation framework was developed through a comprehensive analysis of the deficiencies and potential improvements of the satellite data products, the assimilation procedures and error characterization, and the assimilation effectiveness over time. This analysis motivated the development of a higher frequency GRACE dataset more representative of the hydrometeorological signal content with reduced temporal aliasing of the TWS signal. Three innovations were implemented in the product development: regularization, sliding windows, and mascon basis functions, to develop a high-fidelity daily gravity field product (RSWM). The signal and error profile of the RSWM product was comprehensively analyzed via an end-to-end simulation analysis of the GRACE mission. The simulation analysis developed an error covariance representative of the magnitude, correlation, and spatial pattern of error in the RSWM dataset available for use in the data assimilation system. The assimilation algorithms and tools were advanced to optimally incorporate the GRACE TWS data and error covariance information. Daily assimilation was performed globally at the one degree gridcell level, significantly reducing spatial and temporal smoothing of the assimilation update from previous basin-scale assimilation of the monthly mean GRACE datasets. Framework elements additionally defined the mechanisms of the assimilation process: (i) the Gaspari-Cohn localization radius to spatially smooth the coarser resolution GRACE data, (ii) the necessary assimilation update rate to balance assimilation performance and computational efficiency, and (iii) open-loop error growth after assimilation has conditioned the system to advise data latency requirements. The GRACE data assimilation framework is versatile and adaptable to other land surface models, different formulations of data from the current GRACE mission, and future satellite gravity datasets.Aerospace Engineerin

Score Allotment Optimization Method with Application to Comparison of Ability Evaluation in Testing between Classical Test Theory and Item Response Theory

Many researchers know the superiority of the item response theory (IRT) over the classical test theory (CTT) from a detailed test-evaluation viewpoint. However, teachers are still reluctant to use the IRT as a daily testing tool. The primary objective of this paper is to nd the difference between the CTT and the IRT. In particular, we focus on the difference in ability evaluation. We compared the CTT and IRT evaluated abilities by using the hypothetically assumed abilities that are mimicked to a real case. By using a simulation study, we found that the IRT is superior to the CTT to some extent. The CTT uses pre-assigned allotments contrary to the IRT which has no allotment concept. However, if we regard the ability evaluation by the IRT as the standard, we can nd the most appropriate allotments in the CTT so that the total scores of the CTT are adjusted as close as possible to the abilities obtained by the IRT. This is a kind of allotment optimization problem. We show the methodology in this paper. By applying our methodology to some simulation cases that mimic the real data case, we found an intriguing feature with respect to the pre-assigned allotments. If teachers want to raise the examination pass rate, we guess that they give higher scores than the actual scores achieved by students; we call this jacking-up. Using the allotment optimization, we have found that jacking-up causes higher allotments to easier problems in the CTT

Fatigue Enhancement of Undersized, Drilled Crack-Stop Holes

A common technique used to prevent the propagation of cracks in bridge girders is drilling crack-stop holes at the crack tips. By doing so, stress concentrations at the tip of the cracks are reduced and fatigue life of the bridge is extended. The size of the crack-stop hole is determined by utilizing known material properties and relationships developed through experimentation. However, these equations often result in a crack-stop hole diameter larger than can be practically drilled; therefore, physical limitations force crack-stop holes to be undersized in the field. To raise the effectiveness of the undersized holes to that of full-sized holes, a method is needed to strengthen undersized crack-stop holes. A similar problem was reported in the aerospace industry with fastener holes, which are potential sites for cracks to initiate and propagate. Static mechanical coldworking generated a great deal of interest in the 1970s and was among several processes that were investigated for improving fatigue life of fastener holes. Extensive literature exists showing that static coldworking of fastener holes can increase fatigue-life-to-failure by a factor from three to ten, depending on stress range. The purpose of this study is to develop a technique to improve the fatigue lives of undersized, crack-stop holes. The technique under development uses piezoelectric transducers operated at ultrasonic frequencies to improve upon recognized coldworking techniques. The piezoelectric transducers duplicate the residual compressive stresses produced by static cold expansion and hopefully change grain size. These residual compressive stresses act as a barrier to crack initiation by reducing the stress concentration at the hole. In addition, this new technique is expected to change the crystalline structure of the steel in the immediate vicinity surrounding the under-sized hole. It is thought that the excitation from the piezoelectric transducers will refine the grain size and create a more uniform grain size thereby improving fatigue performance. A tool is being developed that utilizes the piezoelectric transducers ability to convert electrical signals into mechanical work. Initially, the tool being developed is a small-scale laboratory device; once the technique is proven, it will be scaled up for use on full-scale bridge members under laboratory conditions. Lastly, a tool using the same technology will be developed for field application. The research includes a set of finite element models created to aid in tool design and to quantify and characterize the residual stresses surrounding the cold expanded crack-stop holes. Results were compared and agreed quite favorably to analyses found in past literature

High pressure conditions promote the proliferation of rat cultured mesangial cells in vitro

AbstractGlomerular capillary pressure is involved in the development of chronic renal failure and has at least two effects on mesangial cells: transmembrane hydrostatic pressure and stretch. To clarify whether pure hydrostatic pressure itself affects the proliferation of cultured rat mesangial cells, we compared the cell number under atmospheric pressure condition with high pressure condition. At 24 and 48h with 0.5% serum, cell number was significantly higher under high pressure condition than under atmospheric pressure condition. At 48h, cell number under high pressure condition was increased in a pressure-dependent manner. Furthermore, flow cytometric assay indicated that pressure-load could promote DNA synthesis rate at S phase and enhance G1/S progression induced by low concentration of serum (0.5%). These results suggest that pure hydrostatic pressure itself can promote the proliferation of cultured rat mesangial cells by advancing cell cycle progression in vitro

Soluble CD163, a unique biomarker to evaluate the disease activity, exhibits macrophage activation in systemic juvenile idiopathic arthritis

13301甲第5245号博士（医学）金沢大学博士論文本文Full 以下に掲載：Cytokine 110 pp.459-465 2018. Elsevier. 共著者：Naoto Sakumura, Masaki Shimizu, Mao Mizuta, Natsumi Inoue, Yasuo Nakagishi, Akihiro Yachi

Quantification of Local Morphodynamics and Local GTPase Activity by Edge Evolution Tracking

Advances in time-lapse fluorescence microscopy have enabled us to directly observe dynamic cellular phenomena. Although the techniques themselves have promoted the understanding of dynamic cellular functions, the vast number of images acquired has generated a need for automated processing tools to extract statistical information. A problem underlying the analysis of time-lapse cell images is the lack of rigorous methods to extract morphodynamic properties. Here, we propose an algorithm called edge evolution tracking (EET) to quantify the relationship between local morphological changes and local fluorescence intensities around a cell edge using time-lapse microscopy images. This algorithm enables us to trace the local edge extension and contraction by defining subdivided edges and their corresponding positions in successive frames. Thus, this algorithm enables the investigation of cross-correlations between local morphological changes and local intensity of fluorescent signals by considering the time shifts. By applying EET to fluorescence resonance energy transfer images of the Rho-family GTPases Rac1, Cdc42, and RhoA, we examined the cross-correlation between the local area difference and GTPase activity. The calculated correlations changed with time-shifts as expected, but surprisingly, the peak of the correlation coefficients appeared with a 6–8 min time shift of morphological changes and preceded the Rac1 or Cdc42 activities. Our method enables the quantification of the dynamics of local morphological change and local protein activity and statistical investigation of the relationship between them by considering time shifts in the relationship. Thus, this algorithm extends the value of time-lapse imaging data to better understand dynamics of cellular function

項目反応理論を用いた野球選手の能力評価指標の提案

要旨ありスポーツ統計科学の新たな挑戦原著論