Sparse estimation in ordinary kriging for functional data

We introduce a sparse estimation in the ordinary kriging for functional data. The functional kriging predicts a feature given as a function at a location where the data are not observed by a linear combination of data observed at other locations. To estimate the weights of the linear combination, we apply the lasso-type regularization in minimizing the expected squared error. We derive an algorithm to derive the estimator using the augmented Lagrange method. Tuning parameters included in the estimation procedure are selected by cross-validation. Since the proposed method can shrink some of the weights of the linear combination toward zeros exactly, we can investigate which locations are necessary or unnecessary to predict the feature. Simulation and real data analysis show that the proposed method appropriately provides reasonable results

Global convergence of a stabilized sequential quadratic semidefinite programming method for nonlinear semidefinite programs without constraint qualifications

In this paper, we propose a new sequential quadratic semidefinite programming (SQSDP) method for solving nonlinear semidefinite programs (NSDPs), in which we produce iteration points by solving a sequence of stabilized quadratic semidefinite programming (QSDP) subproblems, which we derive from the minimax problem associated with the NSDP. Differently from the existing SQSDP methods, the proposed one allows us to solve those QSDP subproblems just approximately so as to ensure global convergence. One more remarkable point of the proposed method is that any constraint qualifications (CQs) are not required in the global convergence analysis. Specifically, under some assumptions without CQs, we prove the global convergence to a point satisfying any of the following: the stationary conditions for the feasibility problem; the approximate-Karush-Kuhn-Tucker (AKKT) conditions; the trace-AKKT conditions. The latter two conditions are the new optimality conditions for the NSDP presented by Andreani et al. (2018) in place of the Karush-Kuhn-Tucker conditions. Finally, we conduct some numerical experiments to examine the efficiency of the proposed method

Modified Armijo line-search in Riemannian optimization with reduced computational cost

In this paper, we propose a new line-search method that improves the ordinary Armijo line-search in Riemannian optimization. For optimization problems on Riemannian manifolds, many types of globally convergent algorithms have been proposed, and they are often equipped with the Armijo line-search in Riemannian optimization for global convergence. Such existing methods need the computation of a retraction regarding the search direction for each iteration. On the other hand, the proposed line-search decreases the computational cost by incorporating a new strategy that computes the retraction only if a promising candidate for the step length is found. We further present a Riemannian Newton method with the new line-search strategy and prove its global convergence

The Nutrient-Responsive Molecular Chaperone Hsp90 Supports Growth and Development in Drosophila

Animals can sense internal nutrients, such as amino acids/proteins, and are able to modify their developmental programs in accordance with their nutrient status. In the fruit fly, Drosophila melanogaster, amino acid/protein is sensed by the fat body, an insect adipose tissue, through a nutrient sensor, target of rapamycin (TOR) complex 1 (TORC1). TORC1 promotes the secretion of various peptide hormones from the fat body in an amino acid/protein-dependent manner. Fat-body-derived peptide hormones stimulate the release of insulin-like peptides, which are essential growth-promoting anabolic hormones, from neuroendocrine cells called insulin-producing cells (IPCs). Although the importance of TORC1 and the fat body-IPC axis has been elucidated, the mechanism by which TORC1 regulates the expression of insulinotropic signal peptides remains unclear. Here, we show that an evolutionarily conserved molecular chaperone, heat shock protein 90 (Hsp90), promotes the expression of insulinotropic signal peptides. Fat-body-selective Hsp90 knockdown caused the transcriptional downregulation of insulinotropic signal peptides. IPC activity and systemic growth were also impaired in fat-body-selective Hsp90 knockdown animals. Furthermore, Hsp90 expression depended on protein/amino acid availability and TORC1 signaling. These results strongly suggest that Hsp90 serves as a nutrient-responsive gene that upregulates the fat body-IPC axis and systemic growth. We propose that Hsp90 is induced in a nutrient-dependent manner to support anabolic metabolism during the juvenile growth period

The Early Arthroscopic Pullout Repair of Medial Meniscus Posterior Root Tear Is More Effective for Reducing Medial Meniscus Extrusion

Clinical studies have demonstrated that transtibial pullout repair led to favorable midterm outcomes in patients with medial meniscus posterior root tears (MMPRTs) although medial meniscal extrusion (MME) continued to be present. It has been unclear whether these residual postoperative MMEs existed after the pullout repair or had progressed at the very short-term evaluation after surgery. We sought to determine which characteristics of patients with MMPRTs influence the incidence of postoperative MME. The cases of 23 patients whose date of injury was known were analyzed. All patients underwent MMPRT pullout fixation. Preoperative and 3-month postoperative magnetic resonance imaging (MRI) examinations were performed. MME was retrospectively assessed on the mid-coronal plane of MRI scans. The preoperative and postoperative MME values were 4.2±1.2 mm and 4.3±1.5 mm, respectively (p=0.559). Pullout repair surgery was performed significantly earlier after the MMPRT-specific injury in patients whose postoperative MME improved compared to the patients whose MME did not improve (p<0.001). Our findings demonstrated that an early transtibial pullout repair of an MMPRT was more effective in reducing MME than a late repair. Surgeons should not miss the optimal timing for the pullout repair of an MMPRT, considering the period from the injury and the preoperative MME

非線形半正定値計画問題に対する最適化手法の研究

京都大学0048新制・課程博士博士(情報学)甲第19122号情博第568号新制||情||100(附属図書館)32073京都大学大学院情報学研究科数理工学専攻(主査)教授 山下 信雄, 教授 太田 快人, 教授 永持 仁学位規則第4条第1項該当Doctor of InformaticsKyoto UniversityDFA

Chaperonin TRiC/CCT supports mitotic exit and entry into endocycle in Drosophila.

Endocycle is a commonly observed cell cycle variant through which cells undergo repeated rounds of genome DNA replication without mitosis. Endocycling cells arise from mitotic cells through a switch of the cell cycle mode, called the mitotic-to-endocycle switch (MES), to initiate cell growth and terminal differentiation. However, the underlying regulatory mechanisms of MES remain unclear. Here we used the Drosophila steroidogenic organ, called the prothoracic gland (PG), to study regulatory mechanisms of MES, which is critical for the PG to upregulate biosynthesis of the steroid hormone ecdysone. We demonstrate that PG cells undergo MES through downregulation of mitotic cyclins, which is mediated by Fizzy-related (Fzr). Moreover, we performed a RNAi screen to further elucidate the regulatory mechanisms of MES, and identified the evolutionarily conserved chaperonin TCP-1 ring complex (TRiC) as a novel regulator of MES. Knockdown of TRiC subunits in the PG caused a prolonged mitotic period, probably due to impaired nuclear translocation of Fzr, which also caused loss of ecdysteroidogenic activity. These results indicate that TRiC supports proper MES and endocycle progression by regulating Fzr folding. We propose that TRiC-mediated protein quality control is a conserved mechanism supporting MES and endocycling, as well as subsequent terminal differentiation