Characteristic Scales of Baryon Acoustic Oscillations from Perturbation Theory: Non-linearity and Redshift-Space Distortion Effects

An acoustic oscillation of the primeval photon-baryon fluid around the decoupling time imprints a characteristic scale in the galaxy distribution today, known as the baryon acoustic oscillation (BAO) scale. Several on-going and/or future galaxy surveys aim at detecting and precisely determining the BAO scale so as to trace the expansion history of the universe. We consider nonlinear and redshift-space distortion effects on the shifts of the BAO scale in $k$-space using perturbation theory. The resulting shifts are indeed sensitive to different choices of the definition of the BAO scale, which needs to be kept in mind in the data analysis. We present a toy model to explain the physical behavior of the shifts. We find that the BAO scale defined as in Percival et al. (2007) indeed shows very small shifts ($\lesssim$ 1%) relative to the prediction in {\it linear theory} in real space. The shifts can be predicted accurately for scales where the perturbation theory is reliable.Comment: 21 pages, 9 figures, references and supplementary sections added, accepted for publication in PAS

小脳神経膠腫の網羅的分子プロファイル解析

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 柴田 龍弘, 東京大学教授 間野 博行, 東京大学教授 古川 洋一, 東京大学准教授 垣内 千尋, 東京大学特任准教授 三井 純University of Tokyo(東京大学

A Study on Acoustic Theoretical Formulae for Compact Acoustic Reproduction Systems

ABSTRACT In this paper, we propose a method for analyzing compact acoustic reproduction systems (e.g. mobile phones) through acoustic equivalent circuits. Measured responses of compact acoustic reproduction systems cannot be represented accurately by the analysis based on the conventional acoustic theory. Acoustic engineers consequently are obliged to design compact acoustic reproduction systems by trial and error. Moreover, the sound quality of those systems is likely to deteriorate due to the difficulty of such an acoustic design. We therefore clarify the cause of the difference between the measured response and the analysis one calculated by the finite element method (FEM) analysis and consider the possibility of obtaining new acoustic theorical formulae based on the analysis results in order to make it easier for acoustic engineers to design compact acoustic reproduction systems

Decision making based on optical excitation transfer via near-field interactions between quantum dots

Optical near-field interactions between nanostructured matter, such as quantum dots, result in unidirectional optical excitation transfer when energy dissipation is induced. This results in versatile spatiotemporal dynamics of the optical excitation, which can be controlled by engineering the dissipation processes and exploited to realize intelligent capabilities such as solution searching and decision making. Here we experimentally demonstrate the ability to solve a decision making problem on the basis of optical excitation transfer via near-field interactions by using colloidal quantum dots of different sizes, formed on a geometry-controlled substrate. We characterize the energy transfer behavior due to multiple control light patterns and experimentally demonstrate the ability to solve the multi-armed bandit problem. Our work makes a decisive step towards the practical design of nanophotonic systems capable of efficient decision making, one of the most important intellectual attributes of the human brain

Distinctive Doping Dependence of Upper Critical Field in Iron-Based Superconductor LaFeAsO1−x_{1-x}Hx_{x}

High magnetic fields up to 105 T have been utilized in deriving the upper critical field $B_{\rm c2}$ of LaFeAsO$_{1-x}$H$_x$ throughout whole temperatures below $T_{\rm c}$. Resistivity measurements demonstrate that $B_{\rm c2}$ behaves differently in samples with $x = 0.12$ (SC1) from those with 0.32 (SC2). In SC1, the two-band model assuming the $s$-wave pairing gives a good fitting with repulsive intraband interaction and dominant interband coupling. In SC2, we have to assume attractive intraband interaction with weak interband coupling, which in fact suggests a non-$s$-wave pairing in view of the strong Coulomb repulsion. These results support the possibility that SC1 and SC2 have different pairing symmetries

High-field phase diagram of a chiral-lattice antiferromagnet Sr(TiO)Cu4(PO4)4

High-field phase diagram of a chiral-lattice antiferromagnet Sr(TiO)Cu4(PO4)4 is studied by means of the ultrasound, dielectric, and magnetocaloric-effect measurements. These experimental techniques reveal two new phase transitions at high fields, which have not been resolved by the previous magnetization experiments. Specifically, the c66 acoustic mode shows drastic changes with hysteresis with applied fields along the c axis, indicating a strong magneto-elastic coupling. Combined with the cluster mean-field theory, we discuss the origins of these phase transitions. By considering the chiral-twist effect of Cu4O12 cupola units, which is inherent to the chiral crystal structure, the phase diagram is reasonably reproduced. The agreement between the experiment and theory suggests that this material is a unique quasi two-dimensional spin system with competing exchange interactions and chirality, leading to the rich phase diagram.Comment: 12 pages, 11 figures, 1 tabl

Allelotypes of lung adenocarcinomas featuring ALK fusion demonstrate fewer onco- and suppressor gene changes

BACKGROUND: A subset of lung adenocarcinomas harboring an EML4-ALK fusion gene resulting in dominant oncogenic activity has emerged as a target for specific therapy. EML4-ALK fusion confers a characteristic histology and is detected more frequently in never or light smokers and younger patients. METHODS: To gain insights into etiology and carcinogenic mechanisms we conducted analyses to compare allelotypes of 35 ALK fusion-positive and 95 -negative tumours using single nucleotide polymorphism (SNP) arrays and especially designed software which enabled precise global genomic profiling. RESULTS: Overall aberration numbers (gains + losses) of chromosomal alterations were 8.42 and 9.56 in tumours with and without ALK fusion, respectively, the difference not being statistically significant, although patterns of gain and loss were distinct. Interestingly, among selected genomic regions, oncogene-related examples such as 1p34.3(MYCL1), 7q11.2(EGFR), 7p21.1, 8q24.21(MYC), 16p13.3, 17q12(ERBB2) and 17q25.1 showed significantly less gain. Also, changes in tumour suppressor gene-related regions, such as 9p21.3 (CDKN2A) 9p23-24.1 (PTPRD), 13q14.2 (RB1), were significantly fewer in tumours with ALK fusion. CONCLUSION: Global genomic comparison with SNP arrays showed tumours with ALK fusion to have fewer alterations in oncogenes and suppressor genes despite a similar overall aberration frequency, suggesting very strong oncogenic potency of ALK activation by gene fusion