Robust and Sparse Regression via γ\gamma-divergence

In high-dimensional data, many sparse regression methods have been proposed. However, they may not be robust against outliers. Recently, the use of density power weight has been studied for robust parameter estimation and the corresponding divergences have been discussed. One of such divergences is the $\gamma$-divergence and the robust estimator using the $\gamma$-divergence is known for having a strong robustness. In this paper, we consider the robust and sparse regression based on $\gamma$-divergence. We extend the $\gamma$-divergence to the regression problem and show that it has a strong robustness under heavy contamination even when outliers are heterogeneous. The loss function is constructed by an empirical estimate of the $\gamma$-divergence with sparse regularization and the parameter estimate is defined as the minimizer of the loss function. To obtain the robust and sparse estimate, we propose an efficient update algorithm which has a monotone decreasing property of the loss function. Particularly, we discuss a linear regression problem with $L_1$ regularization in detail. In numerical experiments and real data analyses, we see that the proposed method outperforms past robust and sparse methods.Comment: 25 page

Ground state of the spin-1/2 chain of green dioptase at high fields

The gem-stone dioptase Cu6Si6O18.6H2O has a chiral crystal structure of equilateral triangular helices consisting of Cu-3d spins. It shows an antiferromagnetic order with an easy axis along c at TN = 15.5 K under zero field, and a magnetization jump at HC = 13.5 T when the field is applied along c-axis. By 29Si-NMR measurements, we have revealed that the high-field state is essentially the two sub-lattice structure, and that the component within ab-plane is collinear. The result indicates no apparent match with the geometrical pattern of helical spin chain.Comment: SCES2013, Hongo, Toky

A simple optimization can improve the performance of single feature polymorphism detection by Affymetrix expression arrays

<p>Abstract</p> <p>Background</p> <p>High-density oligonucleotide arrays are effective tools for genotyping numerous loci simultaneously. In small genome species (genome size: < ~300 Mb), whole-genome DNA hybridization to expression arrays has been used for various applications. In large genome species, transcript hybridization to expression arrays has been used for genotyping. Although rice is a fully sequenced model plant of medium genome size (~400 Mb), there are a few examples of the use of rice oligonucleotide array as a genotyping tool.</p> <p>Results</p> <p>We compared the single feature polymorphism (SFP) detection performance of whole-genome and transcript hybridizations using the Affymetrix GeneChip^®Rice Genome Array, using the rice cultivars with full genome sequence, <it>japonica </it>cultivar Nipponbare and <it>indica </it>cultivar 93-11. Both genomes were surveyed for all probe target sequences. Only completely matched 25-mer single copy probes of the Nipponbare genome were extracted, and SFPs between them and 93-11 sequences were predicted. We investigated optimum conditions for SFP detection in both whole genome and transcript hybridization using differences between perfect match and mismatch probe intensities of non-polymorphic targets, assuming that these differences are representative of those between mismatch and perfect targets. Several statistical methods of SFP detection by whole-genome hybridization were compared under the optimized conditions. Causes of false positives and negatives in SFP detection in both types of hybridization were investigated.</p> <p>Conclusions</p> <p>The optimizations allowed a more than 20% increase in true SFP detection in whole-genome hybridization and a large improvement of SFP detection performance in transcript hybridization. Significance analysis of the microarray for log-transformed raw intensities of PM probes gave the best performance in whole genome hybridization, and 22,936 true SFPs were detected with 23.58% false positives by whole genome hybridization. For transcript hybridization, stable SFP detection was achieved for highly expressed genes, and about 3,500 SFPs were detected at a high sensitivity (> 50%) in both shoot and young panicle transcripts. High SFP detection performances of both genome and transcript hybridizations indicated that microarrays of a complex genome (e.g., of <it>Oryza sativa</it>) can be effectively utilized for whole genome genotyping to conduct mutant mapping and analysis of quantitative traits such as gene expression levels.</p

Multifrequency VLBI Observations of the Broad Absorption Line Quasar J1020+4320: Recently Restarted Jet Activity?

This paper reports very-long-baseline interferometry observations of the radio-loud broad absorption line (BAL) quasar J1020+4320 at 1.7, 2.3, 6.7, and 8.4 GHz using the Japanese VLBI network (JVN) and European VLBI network (EVN). The radio morphology is compact with a size of ~10 pc. The convex radio spectrum is stable over the last decade; an observed peak frequency of 3.2 GHz is equivalent to 9.5 GHz in the rest frame, suggesting an age of the order of ~100 years as a radio source, according to an observed correlation between linear size and peak frequency of compact steep spectrum (CSS) and giga-hertz peaked spectrum (GPS) radio sources. A low-frequency radio excess suggests relic of past jet activity. J1020+4320 may be one of the quasars with recurrent and short-lived jet activity during a BAL-outflowing phase.Comment: 7 pages, 2 figures, 2 tables, accepted for publication in PAS

Effects of Wnt-β-Catenin Signaling and Sclerostin on the Phenotypes of Rat Pheochromocytoma PC12 Cells

Pheochromocytomas and paragangliomas (PPGLs) are classified into 3 major categories with distinct driver genes: pseudohypoxia, kinase signaling, and Wnt-altered subtypes. PPGLs in the Wnt-altered subtype are sporadic and tend to be aggressive with metastasis, where somatic gene fusions affecting mastermind-like 3 (MAML3) and somatic mutations in cold shock domain containing E1 (CSDE1) cause overactivation of Wnt-β-catenin signaling. However, the relation between Wnt-β-catenin signaling and the biological behavior of PPGLs remains unexplored. In rat pheochromocytoma PC12 cells, Wnt3a treatment enhanced cell proliferation and suppressed mRNA expression of tyrosine hydroxylase (TH), the rate-limiting enzyme of catecholamine biosynthesis, and dopamine secretion. We identified the expression of sclerostin in PC12 cells, which is known as an osteocyte-derived negative regulator for Wnt signaling-driven bone formation. Inhibition of endogenous Wnt pathway by XAV939 or sclerostin resulted in attenuated cell proliferation and increased TH expression. Furthermore, Wnt3a pretreatment suppressed bone morphogenetic protein (BMP)-induced Smad1/5/9 phosphorylation whereas BMPs enhanced sclerostin expression in PC12 cells. In the Wnt-altered subtype, the increased Wnt-β-catenin pathway may contribute the aggressive clinical behavior with reduced catecholamine production. Furthermore, upregulated expression of sclerostin by BMPs may explain the osteolytic metastatic lesions observed in metastatic PPGLs

Complete Dissection of a Hepatic Segment after Blunt Abdominal Injury Successfully Treated by Anatomical Hepatic Lobectomy: Report of a Case

A 21-year-old male patient was transferred to the emergency room of our hospital after suffering seat belt abdominal injury in a traffic accident. Abdominal computed tomography revealed a massive hematoma in the abdominal cavity associated with deep hepatic lacerations in the right lobe. The presence of a solid tissue possibly containing pneumobilia was observed above the greater omentum. These findings were consistent with a tentative diagnosis of hepatic laceration due to blunt trauma; therefore, this prompted us to perform emergency laparotomy. The operative findings revealed a massive hematoma and pulsatile bleeding from the lacerated liver and a retroperitoneal hepatoma, which was most likely due to subcapsular injury of the right kidney. In accordance with the preoperative imaging studies, a pale liver fragment on the greater omentum was observed, which was morphologically consistent with the defect in the posterior segment of the liver. Since the damaged area of the liver broadly followed the course of the middle hepatic vein, we carefully inspected and isolated the inflow vessels and eventually performed a right hepatic lobectomy. The patient's postoperative course was uneventful, and he was doing well at 10 months after surgery

Alterations of circulating endothelial cell and endothelial progenitor cell counts around the ovulation.

Context:Circulating endothelial cells (CECs) and progenitor cells (CEPs) have been intensively studied as a promising tool for treating ischemic diseases and monitoring cancer treatments, but how the menstrual cycle affects the variation in their counts remains unclear. Objective:The aims of the study were to determine the influence of the menstrual cycle on the number of CECs and CEPs and to investigate the association of their counts with circulating hormones and angiogenesis-associated factors. Design:CEP and CEC counts by flow cytometry and the CellSearch system and circulating factor levels were measured eight times during the menstrual cycle in 18 volunteers. The menstrual cycle was divided into six phases based on hormone concentrations. Results:CEP counts peaked in the periovulatory and middle luteal phases with a drop in the early luteal phase. CEC counts showed no significant variation. There were significant correlations between the CEP counts and the serum concentrations of estradiol (E2), LH, and granulocyte colony-stimulating factor (G-CSF) (P < 0.0001, P < 0.0001, and P = 0.01, respectively). The difference in CEP counts between two adjacent phases was significantly correlated with that in E2, LH, G-CSF, and serum vascular endothelial growth factor (P < 0.0001, P < 0.0001, P = 0.02, and P = 0.006, respectively). Conclusion:CEP counts peaked in the periovulatory and middle luteal phases, with a drop in the early luteal phase, and were correlated with serum E2, LH, and G-CSF concentrations. Consideration of the variation in CEP counts would be important for the clinical application of CEPs

Three-dimensional electronic structure in ferromagnetic Fe3Sn2\textrm{Fe}_3\textrm{Sn}_2 with breathing kagome bilayers

A large anomalous Hall effect (AHE) has been observed in ferromagnetic $\textrm{Fe}_3\textrm{Sn}_2$ with breathing kagome bilayers. To understand the underlying mechanism for this, we investigate the electronic structure of $\textrm{Fe}_3\textrm{Sn}_2$ by angle-resolved photoemission spectroscopy (ARPES). In particular, we use both vacuum ultraviolet light (VUV) and soft x ray (SX), which allow surface-sensitive and relatively bulk-sensitive measurements, respectively, and distinguish bulk states from surface states, which should be unlikely related to the AHE. While VUV-ARPES observes two-dimensional bands mostly due to surface states, SX-ARPES reveals three-dimensional band dispersions with a periodicity of the rhombohedral unit cell in the bulk. Our data show a good consistency with a theoretical calculation based on density functional theory, suggesting a possibility that $\textrm{Fe}_3\textrm{Sn}_2$ is a magnetic Weyl semimetal.Comment: 6 pages, 4 figure