高次元小標本における固有空間の構造に基づく二標本検定

筑波大学 (University of Tsukuba)201

Empirical Bayesian significance measure of neuronal spike response

Background: Functional connectivity analyses of multiple neurons provide a powerful bottom-up approach to reveal functions of local neuronal circuits by using simultaneous recording of neuronal activity. A statistical methodology, generalized linear modeling (GLM) of the spike response function, is one of the most promising methodologies to reduce false link discoveries arising from pseudo-correlation based on common inputs. Although recent advancement of fluorescent imaging techniques has increased the number of simultaneously recoded neurons up to the hundreds or thousands, the amount of information per pair of neurons has not correspondingly increased, partly because of the instruments' limitations, and partly because the number of neuron pairs increase in a quadratic manner. Consequently, the estimation of GLM suffers from large statistical uncertainty caused by the shortage in effective information. Results: In this study, we propose a new combination of GLM and empirical Bayesian testing for the estimation of spike response functions that enables both conservative false discovery control and powerful functional connectivity detection. We compared our proposed method's performance with those of sparse estimation of GLM and classical Granger causality testing. Our method achieved high detection performance of functional connectivity with conservative estimation of false discovery rate and q values in case of information shortage due to short observation time. We also showed that empirical Bayesian testing on arbitrary statistics in place of likelihood-ratio statistics reduce the computational cost without decreasing the detection performance. When our proposed method was applied to a functional multi-neuron calcium imaging dataset from the rat hippocampal region, we found significant functional connections that are possibly mediated by AMPA and NMDA receptors. Conclusions: The proposed empirical Bayesian testing framework with GLM is promising especially when the amount of information per a neuron pair is small because of growing size of observed network

Asymptotic properties of the first principal component and equality tests of covariance matrices in high-dimension, low-sample-size context

A common feature of high-dimensional data is that the data dimension is high, however, the sample size is relatively low. We call such data HDLSS data. In this paper, we study asymptotic properties of the first principal component in the HDLSS context and apply them to equality tests of covariance matrices for high-dimensional data sets. We consider HDLSS asymptotic theories as the dimension grows for both the cases when the sample size is fixed and the sample size goes to infinity. We introduce an eigenvalue estimator by the noise-reduction methodology and provide asymptotic distributions of the largest eigenvalue in the HDLSS context. We construct a confidence interval of the first contribution ratio and give a one-sample test. We give asymptotic properties both for the first PC direction and PC score as well. We apply the findings to equality tests of two covariance matrices in the HDLSS context. We provide numerical results and discussions about the performances both on the estimates of the first PC and the equality tests of two covariance matrices

High Dimensional Statistical Analysis and its Application to ALMA Map of NGC 253

In astronomy, if we denote the dimension of data as $d$ and the number of samples as $n$, we often meet a case with $n \ll d$. Traditionally, such a situation is regarded as ill-posed, and there was no choice but to throw away most of the information in data dimension to let $d < n$. The data with $n \ll d$ is referred to as high-dimensional low sample size (HDLSS). {}To deal with HDLSS problems, a method called high-dimensional statistics has been developed rapidly in the last decade. In this work, we first introduce the high-dimensional statistical analysis to the astronomical community. We apply two representative methods in the high-dimensional statistical analysis methods, the noise-reduction principal component analysis (NRPCA) and regularized principal component analysis (RPCA), to a spectroscopic map of a nearby archetype starburst galaxy NGC 253 taken by the Atacama Large Millimeter/Submillimeter Array (ALMA). The ALMA map is a typical HDLSS dataset. First we analyzed the original data including the Doppler shift due to the systemic rotation. The high-dimensional PCA could describe the spatial structure of the rotation precisely. We then applied to the Doppler-shift corrected data to analyze more subtle spectral features. The NRPCA and RPCA could quantify the very complicated characteristics of the ALMA spectra. Particularly, we could extract the information of the global outflow from the center of NGC 253. This method can also be applied not only to spectroscopic survey data, but also any type of data with small sample size and large dimension.Comment: 33 pages, 21 figures, accepted for publication in ApJS (Jan. 31, 2024

第1107回千葉医学会例会・第8回環境生命医学研究会

<p>Prevalence of severe depressive symptoms with 95% confidence intervals by sarcopenia and obesity status in the Kashiwa study.</p

Incipient space weathering on asteroid 162173 Ryugu recorded by pyrrhotite

Regolith samples returned from asteroid 162173 Ryugu by the Hayabusa2 mission provide direct means to study how space weathering operates on the surfaces of hydrous asteroids. The mechanisms of space weathering, its effects on mineral surfaces, and the characteristic time scales on which alteration occurs are central to understanding the spectroscopic properties and the taxonomy of asteroids in the solar system. Here, we investigate the behavior of the iron monosulfides mineral pyrrhotite (Fe1−xS) at the earliest stages of space weathering. Using electron microscopy methods, we identified a partially exposed pyrrhotite crystal that morphologically shows evidence for mass loss due to exposure to solar wind ion irradiation. We find that crystallographic changes to the pyrrhotite can be related to sulfur loss from its space‐exposed surface and the diffusive redistribution of resulting excess iron into the interior of the crystal. Diffusion profiles allow us to estimate an order of magnitude of the exposure time of a few thousand years consistent with previous estimates of space exposure. During this interval, the adjacent phyllosilicates did not acquire discernable damage, suggesting that they are less susceptible to alteration by ion irradiation than pyrrhotite

The survey on the implementation of health checkups targeting under 40 years in municipalities

PDF近年、40歳未満の若年成人からメタボリックシンドロームおよび生活習慣病一次予防が重要視されつつある。現在、約８割の自治体で40歳未満の健診機会がない者を対象とした健診（以下、40歳未満健診）が実施され、特に子育て中の被扶養者女性などが受けやすい健診となっている。しかし、この年代は他の年代と比べて健診無関心層が多く、理由に子育てで余裕がない、自身の健康を意識しづらい、健診日程・託児の制約等が挙げられる。一方、自治体の実施状況は様々で、健診中の託児や健診日・場所の充実等の受診環境は国民健康保険被保険者数（以下、被保険者数）や自治体の財政力（以下、財政力指数）によって異なると考える。本研究の目的は、被保険者数規模および財政力指数によって、各自治体の40歳未満健診の詳細な実施状況を明らかにし、自治体規模による今後のよりよい実施に向けて示唆を得ることである。 　関東１都６県、自治体307箇所での40歳未満健診の実施内容を研究対象とした。自治体ホームページで公開されている40歳未満健診の実施に関する情報、自治体別の被保険者数規模・財政力指数を抽出した。被保険者数は「10万人以上」「５万人以上10万人未満」「１万人以上５万人未満」「３千人以上１万人未満」「３千人未満」の５区分にし、40歳未満健診の実施有無および詳細な実施状況との関連でχ2検定を実施し、調整済み残差を計算した。財政力指数との関連では、Mann-Whitney U検定、相関分析を実施した。 　自治体307カ所中、40歳未満健診を実施している自治体保険者は215カ所（70.0%）あった。実施している215カ所中、「10万人以上」で12（70.6%）、「５万人以上10万人未満」で21（77.8%）、「１万人以上５万人未満」で107（70.4%）、「３千人以上１万人未満」で50（67.6%）、「３千人未満」で25（67.6%）と、有意差はなかった。「委託医療機関での個別健診」を実施している割合は、「10万人以上」「５万人以上10万人未満」で有意に高く、「３千人以上１万人未満」「３千人未満」で低かった（p ＜0.001）。「健診当日の保健師等との相談あり（集団健診）」は「１万人以上５万人未満」で、「健診後日の結果説明・相談会あり（集団健診）」は、「５万人以上10万人未満」で多かった。「委託医療機関での個別健診」実施、「子宮頸がん検診同時受診可の可能性」がある場合、「健診会場での託児あり（集団健診）」は、それぞれ自治体の財政力指数が有意に高かった（p =0.046, p =0.013, p =0.031）。また、財政力指数が高い自治体で、実施開始年齢が低い傾向があった（Spearmanの相関係数：－0.151, p =0.032）。40歳未満健診の受診率向上のための試みで自治体毎に工夫していると考えられる内容を確認し、自宅健診（スマホdeドック）や託児・子宮頸がん検診同時受診可の周知に関するホームページ上の工夫がみられた。子育て中の女性にとって、「がん検診とセット」が望まれるため、個別健診が可能で受診率向上を目指す自治体は、積極的に同時受診が可能な点をアピールすると良いと考える。「５万人以上10万人未満」「１万人以上５万人未満」の中規模保険者では、比較的に集団健診当日や後日の保健指導・説明会が実施しやすいことが示唆された。これは、中規模保険者の利点であり、健診受診率の向上を目指す自治体にとっては、アピールポイントとなりえると考えた。departmental bulletin pape

Time-reversal method and cross-correlation techniques by normal mode theory: a three-point problem

International audienceSince its beginning in acoustics, the Time-Reversal method (hereafter referred as TR) has been explored by different studies to locate and characterize seismic sources in elastic media. But few authors have proposed an analytical analysis of the method, especially in the case of an elastic medium and for a finite body such as the Earth. In this paper, we use a normal mode approach (for general 3-D case and degenerate modes in 1-D reference model) to investigate the convergence properties of the TR method. We first investigate a three-point problem, with two fixed points which are the source and the receiver and a third one corresponding to a changing observation point. We extend the problem of a single channel TR experiment to a multiple channel and multiple station TR experiment. We show as well how this problem relates to the retrieval of Green's function with a multiple source cross-correlation and also the differences between TR method and cross-correlation techniques. Since most of the noise sources are located close to the surface of the Earth, we show that the time derivative of the cross-correlation of long-period seismograms with multiple sources at the surface is different from the Green's function. Next, we show the importance of a correct surface-area weighting of the signal resent by the stations according to a Voronoi tessellation of the Earth surface. We use arguments based on the stationary phase approximation to argue that phase-information is more important than amplitude information for getting a good focusing in TR experiment. Finally, by using linear relationships between the time-reversed displacement (resp. strain wavefields) and the components of a vector force source (resp. a moment tensor source), we show how to retrieve force (or moment tensor components) of any long period tectonic or environmental sources by time reversal