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We give a generalized Thurston–Bennequin-type inequality for links in [Formula: see text] using a Bauer–Furuta-type invariant for four-manifolds with contact boundary introduced by the first aut hor. As a special case, we also give an adjunction inequality for smoothly embedded orientable surfaces with negative intersection in a closed oriented smooth four-manifold whose non-equivariant Bauer–Furuta invariant is nonzero.

1.第28回ITER理事会が6月16日17日，オンライン開催された。ITER計画の最新の進捗報告と実績指標の進捗を行った。報告・議論内容を発表した。 2.日本が調達を担当するTFコイル9機のうち、三菱重工㈱が製作担当する第6号機の製作が完了した。製作を担当したメーカーの方が、製作内容、今後の製作への意気込みを語る。 3.東芝エネルギーシステムズ㈱が、TFコイル同社分の初号機を完成させた。製作を担当したメーカーの方が、製作内容、今後の製作への意気込みを語る。 4.ITERサイトでのITER組立状況（2021年4月～）を現地の担当者が発表する。大きなマイルストーンとして、一つ目のサブセクター組立とトカマクピットに配置されたPFコイルについて説明する。 5.7/29に開催された一般向けオンラインセミナーでは、269名の参加があった。セミナー内容と事後アンケートについて発表する。 6.6月、広報資料としてITER職員公募ガイドブック「ITER機構で働こう」を発行した。その内容と目的について説明する。

1.2021年11月17日，18日、第29回ITER理事会が開催され、ITER計画の最新の進捗報告と実績指標の評価を行った。理事会は,、プロジェクトを成功に導くために効果的な協働にコミットしている「One-ITER」チームの取組を賞賛した。 2.日本が製作するITER向け9機のトロイダル磁場（TF）コイルのうち、通算6機目となるTFコイル（TF16）の製作が完了し、12月に工場より出荷された。 3.ITERサイトでのITER組立状況を現地の担当者が発表する。一つ目のサブセクター組立完了と日本製作のTFコイル2機のITERサイト納入について説明する。 4.ITER日本国内機関として核融合とITER計画への理解、ITER機構職員募集を促進するために10月から11月の間に量研が行った広報活動3件について説明する。

Understanding voters’ conception of ideological labels is critical for political behavioral research. Conventional research designs have several limitations, such as endogeneity, insufficient responses to open-ended questions, and inseparability of composite treatment effects. To address these challenges, we propose a conjoint experiment to study the meanings ascribed to ideological labels in terms of policy positions. We also suggest using a mixture model approach to explore heterogeneity in voters’ understandings of ideological labels, as well as the average interpretation of labels. We applied these approaches to conceptions of left–right labels in Japan, where the primary issue of elite-level conflicts has been distinctive compared with other developed countries. We found that, on average, while Japanese voters understand policy-related meanings of “left” and “right,” they primarily associate these labels with security and nationalism, and, secondarily, with social issues; they do not associate these labels with economic issues. Voters’ understandings partly depend on their birth cohort, but observed patterns do not necessarily coincide with what many researchers would predict regarding generational differences in Japanese politics. Mixture model results suggest that some individuals tend to associate left–right labels with security and nationalism policies, while others link them to social policies. Over one-third of respondents seemed to barely understand the usage of left–right labels in policy positions. Our study improves upon existing methods for measuring voter understanding of ideological labels, and reconfirm the global diversity of meanings associated with left–right labels.

The high thermal conductivity of single-walled carbon nanotubes (SWCNTs) has gained much attention for their applications in potential thermal devices. Here, we investigate anharmonic effects, originated from phonon interactions, of SWCNT bundles by temperature dependent Raman imaging using our home-built mini cryostat system. The cryostat system is small enough to be mounted on a piezo scanner that suppresses thermal drift, enabling Raman imaging at different temperatures. We obtained Raman spectral images of several SWCNT bundles with a spatial resolution of a few hundred nanometers at different temperatures. We found that different bundles show different temperature dependences of Raman peak intensity, shift, and width. The temperature dependence was further elucidated by considering the sample topography observed by atomic force microscopy, where bundle effects seem to play an important role to influence the anharmonicity. The temperature-dependent Raman analysis based on spatially resolved imaging will be a powerful tool to investigate anharmonic effects of advanced carbon nanomaterials as well as to realize in situ visualization of thermal properties for future thermal devices.

Hybridization of Bogoliubov quasiparticles (BQPs) between the CuO_{2} layers in the triple-layer cuprate high-temperature superconductor Bi_{2}Sr_{2}Cu_{2}Cu_{3}O_{10+δ} is studied by angle-resolved photoemission spectroscopy (ARPES). In the superconducting state, an anticrossing gap opens between the outer- and inner-BQP bands, which we attribute primarily to interlayer single-particle hopping with possible contributions from interlayer Cooper pairing. We find that the d-wave superconducting gap of both BQP bands smoothly develops with momentum without an abrupt jump in contrast to a previous ARPES study. Hybridization between the BQPs also gradually increases in going from the off nodal to the antinodal region, which is explained by the momentum dependence of the interlayer single-particle hopping. As possible mechanisms for the enhancement of the superconducting transition temperature, the hybridization between the BQPs as well as the combination of phonon modes of the triple CuO_{2} layers and spin fluctuations represented by a four-well model are discussed.

How do the predictable COVID-19-related medical and economic crises affect public opinion? To answer this question, we analyze a nationwide random sampling survey (n = 2053 respondents) coinciding with the period from the beginning of the outbreak of COVID-19 to its peak. This scale and timing enable us to trace a shift in public opinion. We find that the levels of public support for big government had increased before the spread of COVID-19. Furthermore, the results show that with the sudden growth of patients, people predicted a future economic crisis and thus demanded the government to implement economic stimulus measures to reduce damage. Our findings imply that public opinion is formed earlier than crises actually materialize.

Conventional superconductivity is caused by electron-phonon coupling. The discovery of high-temperature superconductors raised the question of whether such strong electron-phonon coupling is realized in cuprates. Strong coupling with some collective excitation mode has been indicated by a dispersion "kink". However, there is intensive debate regarding whether the relevant coupling mode is a magnetic resonance mode or an oxygen buckling phonon mode. This ambiguity is a consequence of the energy of the main prominent kink. Here, we show a new landscape of dispersion kinks. We report that heavily overdoping a Bi

The emergence of quantization at the nanoscale, the quantum size effect (QSE), allows flexible control of matter and is a rich source of advanced functionalities. A QSE-induced transition into an insulating phase in semimetallic nanofilms was predicted for bismuth a half-century ago and has regained new interest with regard to its surface states exhibiting nontrivial electronic topology. Here, we reveal an unexpected mechanism of the transition by high-resolution angle-resolved photoelectron spectroscopy combined with theoretical calculations. Anomalous evolution and degeneracy of quantized energy levels indicate that increased Coulomb repulsion from the surface states deforms a quantum confinement potential with decreasing thickness. The potential deformation drastically modulates spatial distributions of quantized wave functions, which leads to acceleration of the transition even beyond the original QSE picture. This discovery establishes a complete picture of the long-discussed problem in bismuth and highlights the new class of size effects dominating nanoscale transport in systems with metallic surface states., 22 pages, 10 figures (Supplementary Information included), accepted for publication in Science Advances

Angle-resolved photoemission spectroscopy with low-energy tunable photons along the nodal direction of oxygen isotope substituted ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ reveals a distinct oxygen isotope shift near the electron-boson coupling ``kink'' in the electronic dispersion. The magnitude (a few meV) and direction of the kink shift are as expected due to the measured isotopic shift of phonon frequency, and are also in agreement with theoretical expectations. This demonstrates the participation of the phonons as dominant players, as well as pinpointing the most relevant of the phonon branches.

We investigate the metal to nonmagnetic insulator (MI) transition of MnP-type Ru pnictide RuP using hard x-ray and ultraviolet photoemission spectroscopies. The spectral weight at ${E}_{\mathrm{F}}$ is suppressed below the MI transition temperature ${T}_{\mathrm{MI}}$, while there is no appreciable change across the pseudogap temperature ${T}_{\mathrm{PG}}$. The estimated energy scale of the gap is $\ensuremath{\sim}110$ meV, which is in good correspondence to the spin gap opening observed in the previous NMR study. According to the band structure calculation, the density of states at ${E}_{\mathrm{F}}$ mainly originates from narrow bands of the Ru $4{d}_{xy}$ orbitals. Our results suggest that the fourfold-degenerate Ru $4{d}_{xy}$ orbitals are deeply related to the MI transition. Based on the photoemission results and the band structure calculation, we argue the possible origin of the MI transition for polycrystalline RuP.

We investigated the electronic structures of mono- and few-layered Ru nanosheets (N layers (L) with N = 1, ~6, and ~9) on Si substrate by ultra-violet and x-ray photoemission spectroscopies. The spectral density of states (DOS) near EF of ~6 L and 1 L is suppressed as it approaches EF in contrast to that of ~9 L, which is consistent with the Ru 3 d core-level shift indicating the reduction of the metallic conductivity. A power law g(ε) ∝ |ε − εF|α well reproduces the observed spectral DOS of ~6 L and 1 L. The evolution of the power factor α suggests that the transition from the metallic state of ~9 L to the 2-dimensional insulating state with the soft Coulomb gap of 1 L through the disordered 3-dimensional metallic state of ~6 L.

We construct an obstruction for the existence of embeddings of homology $3$-sphere into homology $S^3\times S^1$ under some cohomological condition. The obstruction is defined as an element in the filtered version of the instanton Floer cohomology due to R.Fintushel-R.Stern. We make use of the $\mathbb{Z}$-fold covering space of homology $S^3\times S^1$ and the instantons on it., Comment: 34 pages

We report substantial advance of our low-energy angle-resolved photoemission study of nodal quasiparticles in Bi2Sr2CaCu2 O 8 + δ . The new data cover the samples from underdoped down to heavily underdoped levels. We also present the nodal Fermi velocities that determined by using an excitation-photon energy of h ν = 7.0 eV over a wide doping range. The consistency between the results with h ν = 8.1 and 7.0 eV allows us to rule out the effect of photoemission matrix elements. In comparison with the data previously reported, the nodal effective mass increases by a factor of ∼ 1.5 in going from optimally doped to heavily underdoped levels. We find a rapid enhancement of the nodal quasiparticle mass at low doping levels near the superconductor-to-insulator transition. The effective coupling spectrum, λ ( ω ) , is extracted directly from the energy derivatives of the quasiparticle dispersion and scattering rate, as a causal function of the mass enhancement factor. A steplike increase in Re λ ( ω ) around ∼ 65 meV is demonstrated clearly by the Kramers-Kronig transform of Im λ ( ω ) . To extract the low-energy renormalization effect, we calculated a simple model for the electron-boson interaction. This model reveals that the contribution of the renormalization at | ω | ≤ 15 meV to the quasiparticle mass is larger than that around 65 meV in underdoped samples.

We report the global structural alterations in histone H3 proteins induced by lysine-9 mono-, di- and trimethylation, which are part of the critical post-translational modifications for DNA damage responses, identified using synchrotron radiation circular dichroism (CD) spectroscopy. Compared with unmodified H3, mono- and dimethylation increases the number of α-helices and decreases the numbers of β-strands, while trimethylation decreases the α-helix content and increases the β-strand content. Comparison of the secondary-structure contents of these histone H3 proteins suggests that the methylation-induced structural alterations occur at residues not only close to but also distant from the methylated sites. Such global structural alterations may regulate the interactions of methylated histones with other molecules, such as histone-binding proteins in DNA damage repair processes.

We have developed a laser-based scanning angle-resolved photoemission spectroscopy system (µ-ARPES) equipped with a high precision 6-axis control system, realizing not only high-resolution photoemission spectroscopy in energy and momentum, but also spatial resolution of a µm scale. This enables our µ-ARPES system to probe fine details of intrinsic electronic states near the Fermi level such as the superconducting gaps and lifetime broadening.

We have investigated the electronic structures of Y1-xTmxB6 (x = 0, 0.25) and Yb1-xTmxB6 (x = 0, 0.2) by means of hard x-ray photoemission spectroscopy (HAXPES) at h ν = 5.95 keV. The Tm 3d HAXPES revealed that the valence of Tm in YB6 is ∼2.6 at 300 K and ∼2.5 at 20 K, indicating strong valence fluctuation. In contrast, Tm in YbB6 is almost trivalent independent of temperature. Yb in YbB6 is almost divalent and the Yb2+ state is stabilized by the Tm doping.

We have investigated bulk-derived electronic structure of the valence transition system Eu(Rh 1– x Co x ) 2 Si 2 with x = 0 and 0.4 by means of hard x-ray photoemission spectroscopy. The Eu mean valence evaluated from the Eu 3 d spectrum for x = 0.4 gradually changes from 2.57 at 300 K to 2.92 at 20 K. On the other hand, the valence for x = 0 retains ∼2.1 in the temperature range from 300 to 20 K. Furthermore, the Eu 2+ 4 f component in the valence band for x = 0.4 was shifted by 150 meV towards the Fermi level compared to that for x = 0. Present results suggest that the increase in the hybridization strength between Eu 4 f and conduction electrons induces the valence transition, which is consistent with the Kondo volume collapse model.

Synchrotron-radiation circular-dichroism spectroscopy was used to reveal that the DNA damage response induces a decrement of α-helix and an increment of β-strand contents of histone H3–H4 extracted from X-ray–irradiated human HeLa cells. The trend of the structural alteration was qualitatively opposite to that of our previously reported results for histone H2A–H2B. These results strongly suggest that histones share roles in DNA damage responses, particularly in DNA repair processes and chromatin remodeling, via a specific structural alteration of each histone.

We study the electronic structure of p-trifluoromethylphenyl nitronyl nitroxide (p-CF3PNN), which forms a one-dimensional alternating antiferromagnetic chain of molecules, using angle-resolved photoemission spectroscopy. A singly occupied molecular orbital (SOMO) is observed clearly at ∼ 2 eV in the valence-band spectra. The small band gap and the overlap between the SOMO orbitals in the NO groups are associated with the antiferromagnetic interaction between neighboring spins.

We studied the electronic structure of YbCdCu4, which is known as a heavy fermion compound, by means of photoe- mission spectroscopy. An energy shift and an intensity enhancement of the Yb2+ 4 f7/2 peak are clearly observed with decreasing temperature. The characteristic energy scale of the Kondo temperature is estimated as ~26.5 meV, which is in agreement with the Kondo temperature obtained by the magnetic susceptibility measurements. It suggests that the observed 4 f7/2 state is associated with the heavy fermion behavior of YbCdCu4.We studied the electronic structure of YbCdCu4, which is known as a heavy fermion compound, by means of photoe- mission spectroscopy. An energy shift and an intensity enhancement of the Yb2+ 4 f7/2 peak are clearly observed with decreasing temperature. The characteristic energy scale of the Kondo temperature is estimated as ~26.5 meV, which is in agreement with the Kondo temperature obtained by the magnetic susceptibility measurements. It suggests that the observed 4 f7/2 state is associated with the heavy fermion behavior of YbCdCu4.

We have studied the electronic structure of the stripe-type charge-orbital ordered phase of IrTe2 by means of angle-resolved photoemission spectroscopy. An electron pocket at the Brillouin zone boundary and hole Fermi surfaces around its center are clearly observed in agreement with the band structure calculation for the stripe-type charge-orbital ordered phase. The present study indicates that the hole and electron Fermi surfaces can survive due to the strong Te 5p spin-orbit coupling even under the charge-orbital order. The participant of the Te 5p orbitals to the conduction band provides an interesting interplay between the charge-orbital order and the spin-orbit interaction in IrTe2.

On the question of how voters perceive party positions, much of the existing literature has not adequately considered the case of a multidimensional policy space. Since the ideological cues related to each issue differ in a policy space of multiple dimensions, it is possible that each individual favors different dimensional cues. To test this hypothesis, this paper focuses on Japan’s 2012 Lower House election, which took place in a two-dimensional policy space. An analysis of how voters position the three major parties relative to each other reveals that there is actually heterogeneity in the voter perception of the policy space. Further, using a mixed logit model, we find that demographic factors and political attitudes explain this heterogeneity.

The 2012 presidential election was closely contested with the media predicting that the unemployment rate announcement just before the election would be the deciding factor. If a single economic indicator could buoy up job approval ratings, delivering positive economic statistics to the voters would be a rational re-election strategy for an incumbent. In contrast, this paper presents a model in which voters do not immediately convert each economic statistic into a performance evaluation. Only after many “rehearsals” do voters convert statistics into a positive or negative evaluation. I take the case of Japan and use a survey experiment and an inverse probability weighting (IPW) estimator to assess whether short-, medium- and long-term performance evaluations form based on voter perception of economic conditions.

Knowledge of the conformations of a water-soluble protein bound to a membrane is important for understanding the membrane-interaction mechanisms and the membrane-mediated functions of the protein. In this study we applied vacuum-ultraviolet circular-dichroism (VUVCD) and linear-dichroism (LD) spectroscopy to analyze the conformations of α-lactalbumin (LA), thioredoxin (Trx), and β-lactoglobulin (LG) bound to phosphatidylglycerol liposomes. The VUVCD analysis coupled with a neural-network analysis showed that these three proteins have characteristic helix-rich conformations involving several helical segments, of which two amphiphilic or hydrophobic segments take part in interactions with the liposome. The LD analysis predicted the average orientations of these helix segments on the liposome: two amphiphilic helices parallel to the liposome surface for LA, two hydrophobic helices perpendicular to the liposome surface for Trx, and a hydrophobic helix perpendicular to and an amphiphilic helix parallel to the liposome surface for LG. This sequence-level information about the secondary structures and orientations was used to formulate interaction models of the three proteins at the membrane surface. This study demonstrates the validity of a combination of VUVCD and LD spectroscopy in conformational analyses of membrane-binding proteins, which are difficult targets for X-ray crystallography and nuclear magnetic resonance spectroscopy.

We studied the electronic structure of YbInCu4, which exhibits a first-order valence transition, using angle-resolved photoemission spectroscopy. The dispersive conduction bands and the spin–orbit split Yb 4f7/2 and 4f5/2 states were observed clearly near the Fermi level. We revealed that a flat band located −80 meV below the 4f7/2 state shows a momentum-dependent behavior around the M ¯ point of the surface Brillouin zone, and it was described by a hybridization-band picture based on the periodic Anderson model. We attributed the observed momentum-dependent behavior to the effect of hybridization between the conduction and 4f electrons in the subsurface region of YbInCu4.

We acknowledge partial support from the Saint Petersburg State University (Grant No. 15.61.202.2015), Tomsk State University competitiveness improvement program (Project No. 8.1.01.2017), and the Spanish Ministry of Science and Innovation (Grant No. FIS2016-75862-P). This study was partially supported by the Russian Science Foundation (Projects No. 17-12-01047, for the electrophysical properties, and No. 18-12-00169, for the theoretical calculations) and by the Russian Foundation for Basic Research (Project No. 17-08-00955, for the crystal growth and structural characterization). S.V.E. acknowledges support by the Fundamental Research Program of the State Academies of Sciences for 2013–2020. I.P.R. acknowledges support by the Ministry of Education and Science of the Russian Federation within the framework of the governmental program Megagrants (state task No. 3.8895.2017/P220). A.K. was financially supported by KAKENHI Grants No. 26247064 and No. 17H06138.

Japanese newspapers and television have unique characteristics, even from a global perspective. This chapter explores the structure of the market for newspapers and television – which are at the backbone of mass communication in Japan – and outlines the unique features of Japanese political broadcasting. It then shifts its focus to Japanese politicians themselves and considers their media strategies. Finally, it considers the evolving nature of political communication using the internet, an increasingly growing force in the contemporary Japanese media landscape.

We have studied the electronic structure of SnSe and Na-doped SnSe by means of angle-resolved photoemission spectroscopy. The valence-band top reaches the Fermi level by the Na doping, indicating that Na-doped SnSe can be viewed as a degenerate semiconductor. However, in the Na-doped system, the chemical potential shift with temperature is unexpectedly large and is apparently inconsistent with the degenerate semiconductor picture. The large chemical potential shift and anomalous spectral shape are key ingredients for an understanding of the novel metallic state with the large thermoelectric performance in Na-doped SnSe.

Low-temperature Raman spectroscopy is an interesting technique to investigate molecular vibration by suppressing the thermal interference between the atoms.

We show $ 10/8$-type inequalities for some end-periodic $4$-manifolds which have positive scalar curvature metrics on the ends. As an application, we construct a new family of closed $4$-manifolds which do not admit positive scalar curvature metrics., Comment: 36 pages, 1 figure

Transient electron-hole pairs generated in semiconductors can exhibit unconventional excitonic condensation. Anisotropy in the carrier mass is considered as the key to elongate the life time of the pairs, and hence to stabilize the condensation. Here we employ time- and angle-resolved photoemission spectroscopy to explore the dynamics of photo-generated carriers in black phosphorus. The electronic structure above the Fermi level has been successfully observed, and a massive-and-anisotropic Dirac-type dispersions are confirmed; more importantly, we directly observe that the photo-carriers generated across the direct band gap have the life time exceeding 400 ps. Our finding confirms that black phosphorus is a suitable platform for excitonic condensations, and also open an avenue for future applications in broadband mid-infrared BP-based optoelectronic devices., Comment: 13 pages, 5 figures

Vacuum-ultraviolet (VUV) electronic circular-dichroism (ECD) spectra of methyl β-D-glucopyranoside (methyl β-D-Glc), methyl α -a ndβ-D-galactopyranosides (methyl α -a ndβ-D-Gal), and methyl α -a ndβ-D-xylopyranosides (methyl α -a ndβ-D-Xyl) were measured down to 163 nm in aqueous solution using a synchrotron-radiation VUV-ECD spectropho- tometer. Five methyl aldopyranosides exhibited characteristic ECD spectra depending on the gauche (G) and trans (T) con- formations of the hydroxymethyl group at C-5 and the α-/β-anomer configurations of the methoxy group at C-1. To elucidate the contributions of these structures to the spectrum, the ECD spectra of three rotamers (GT, GG and TG) of methyl β-D-Glc, methyl α-D-Gal and methyl β-D-Gal were calculated using a time-dependent density functional theory and molecular dynam- ics simulations. These theoretical spectra were very similar to those observed experimentally, indicating that the GT and GG rotamers show negative and positive ECD around 170 nm, respectively, and that the α -a ndβ-anomers exhibit negative and positive ECD around 160 nm, respectively. These spectral differences between the two rotamers and between the two anomers were attributable to changes in steric configurations, including the intramolecular hydrogen bond around the ring oxygen and the methoxy oxygen, respectively. These relationships were supported by the ECD spectra experimentally observed for methyl α-D-Xyl and methyl β-D-Xyl, demonstrating that the VUV-ECD spectroscopy is a powerful technique for characterizing the structures of saccharides in aqueous solution.

Newly developed double spin-detectors system utilizing high-efficient very low energy electron diffraction type spin detector for three dimensional spin vectorial analysis is presented. The high efficiency of the spin detector and the state of the art hemispherical electron analyzer enables us to measure all the spin vector components in high energy- and angular-resolution. The detection of orthogonal three spin components (Px, Py and Pz) are important to observe real spin structure of the Rashba systems or topological insulators that are deviating from the ideal in-plane tangential helical spin structure. In addition three dimensional spin analysis is important for the determination of the degree of spin polarization of such systems since the spin quantization axis of the systems is not obvious unlike the ferromagnetic materials.

lectronic structure of the Kondo lattices YbNiX3 (X =Si, Ge) has been investigated by means of hard x-ray photoemission spectroscopy (HAXPES) with hν = 5.95 keV. From the Yb 3d HAXPES spectra, the Yb valence in YbNiSi3 is estimated to be ∼ 2.92, which is almost temperature-independent. On the other hand, the valence in YbNiGe3 is estimated to be 2.48 at 300 K, showing significant valence fluctuation, and gradually decreases to 2.41 at 20 K on cooling. The Ni 2p3/2 and Yb3+ 4f peaks exhibit opposite energy shifts amounting to ∼ 0.6 eV between YbNiSi3 and YbNiGe3. We propose a simple model for the electronic structure of YbNiX3 based on the HAXPES results. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The electronic structure of Yb-based Kondo lattices ${\mathrm{Yb}}_{2}{\mathrm{Pt}}_{6}{X}_{15}$ ($X$=Al, Ga) has been investigated by means of photoemission spectroscopy using hard x-ray ($h\ensuremath{\nu}=5.95$ keV) and vacuum ultraviolet ($h\ensuremath{\nu}=182$ eV) synchrotron radiation. The Yb $3d$ spectra of ${\mathrm{Yb}}_{2}{\mathrm{Pt}}_{6}{X}_{15}$ showed both ${\mathrm{Yb}}^{2+}$- and ${\mathrm{Yb}}^{3+}$-derived structures, directly indicating valence fluctuation. The Yb valences of ${\mathrm{Yb}}_{2}{\mathrm{Pt}}_{6}{\mathrm{Al}}_{15}$ were estimated to be $2.89\ifmmode\pm\else\textpm\fi{}0.01$ at 250 K and $\ensuremath{\sim}2.83$ at 20 K, while those of ${\mathrm{Yb}}_{2}{\mathrm{Pt}}_{6}{\mathrm{Ga}}_{15}$ were $\ensuremath{\sim}2.34$ at 300 K with almost no temperature dependence. With changing $X$ ions from Al to Ga, the Pt $5d$ and Pt $4f$ peaks were shifted to shallower binding energies, and the ${\mathrm{Yb}}^{3+}$ $4f$ peaks were shifted to the deeper binding energies. The $X$ dependences of the Yb valence and the Kondo temperature of ${\mathrm{Yb}}_{2}{\mathrm{Pt}}_{6}{X}_{15}$ are discussed based on the ${\mathrm{Yb}}^{3+}$ $4f$ hole level relative to the Fermi level ${E}_{F}$ and Pt-derived density of states at ${E}_{F}$.

We investigated the bulk-derived electronic structure of the temperature-induced valence transition system ${\mathrm{EuNi}}_{2}$(${\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$)${}_{2}$ ($x=0.70$, 0.79, and 0.82) by means of hard x-ray photoemission spectroscopy (HAXPES). The HAXPES spectra clearly show distinct temperature dependencies in the spectral intensities of the ${\mathrm{Eu}}^{2+}$ and ${\mathrm{Eu}}^{3+}\phantom{\rule{4pt}{0ex}}3d$ components. For $x=0.70$, the changes in the ${\mathrm{Eu}}^{2+}$ and ${\mathrm{Eu}}^{3+}\phantom{\rule{4pt}{0ex}}3d$ spectral components with temperature reflect a continuous valence transition, whereas the sudden changes for $x=0.79$ and 0.82 reflect first-order valence transitions. The Eu $3d$ spectral shapes for all $x$ and particularly the drastic changes in the ${\mathrm{Eu}}^{3+}\phantom{\rule{4pt}{0ex}}3d$ feature with temperature are validated by a theoretical calculation based on the single-impurity Anderson model (SIAM). SIAM analysis reveals that the valence transition for each $x$ is controlled by the $c\ensuremath{-}f$ hybridization strength and the charge-transfer energy. Furthermore, the $c\ensuremath{-}f$ hybridization strength governs the valence transition of this system, which is either first order or continuous, consistent with Kondo volume collapse.