Sr-Nd-Pb isotope systematics of fine sediments from the modern rivers in SW Japan : Implications for sediment provenance of the Northwest Pacific

As reference data for comprehensive provenance analyses of deep-sea sediments in the Northwest Pacific region, we present Sr-Nd-Pb isotopic compositions of fine sediments sampled from 48 rivers in southwest Japan. Sr-Nd-Pb isotope ratios are reliable indicators of sediment sources. Although isotopic data of fine sediments in Chinese arid regions, known to be Asian dust sources, are abundant, comparable data from southwest Japan are scarce, even though southwest Japan, owing to its tectonic activity, is a major sediment source to the Northwest Pacific. Sr-Nd-Pb isotope ratios of our riverine fine sediment samples vary greatly (87Sr/86Sr, 0.707–0.724; 143Nd/144Nd, 0.5120–0.5129; 206Pb/204Pb, 18.16–18.89; 207Pb/204Pb, 15.55–15.66; and 206Pb/204Pb, 38.13–39.09), and these variations are clearly dependent on the principal geology of each river's watershed. These results indicate that these isotope ratios can be effectively used to discriminate the geological sources of the sediments. Sediments from watersheds dominated by Quaternary volcanic rocks have the lowest 87Sr/86Sr and Pb isotope ratios and the highest 143Nd/144Nd ratios, whereas sediments from watersheds dominated by accretionary sedimentary rocks generally have high 87Sr/86Sr and Pb isotope ratios and low 143Nd/144Nd ratios, but their specific values vary depending on the age and geographic location of the rocks. The isotope compositions of sediments from watersheds with exposed Cretaceous granitic and metamorphic rocks are also distinctive. Comparison between the isotope ratios of Japanese river sediments and the Northwest Pacific seafloor sediments suggests the importance of sediment transport by the Kuroshio Current to the Northwest Pacific

アメリカ産ダイズ品種‘UA4805’ の多収性に関する解析的研究－日本品種 ‘あきまろ’ との比較－

Field experiments were conducted in 2020 and 2021 at the Field Science Center of Okayama Univ. (34°41’ N, 133°55’ E). Two Soybean cultivars ‘UA4805’ and ‘Akimaro’ were sown with two planting densities, 12.5plants m−2 (sparse, 80×10cm) and 25plants m−2 (dense, 80×5cm)on May 25 (early), June 29 (normal), and Aug. 3 (late) in 2020, and 80 and 30cm row-width, and 12.5 and 25 plant m−2 in 2021 on June 23. Seed yield was higher in ‘UA4805’ than in ‘Akimaro’ in 2020 and 2021. The later the sowing time, the higher the seeds/stem ratio. Both cultivars showed higher dry matter in dense planting. Dry matter was higher in ‘Akimaro’, while seed yield was lower than ‘UA4805’. In contrast, ‘UA4805’ showed lower dry matter with higher seed yield. The numbers of nodes, pods, and seeds were higher in ‘UA4805’ resulting in the higher seed yield. Lodging score is larger in ‘Akimaro’ especially in dense planting. The seeds/stem ratio is much higher in ‘UA4805’ than ‘Akimaro’ across 2 densities, 3 sowing times and 2 row width. Pods setting ratio was nearly two times higher in ‘UA4805’ compared to ‘Akimaro’. The greater seed yield of ‘UA4805’ compared to ‘Akimaro’ was due to the higher pod setting ratio, seeds/stem ratio, and lower lodging score, nevertheless the dry matter was larger in ‘Akimaro’. If late sowing is applied, higher planting density is recommended for better seed yield. Narrow row is an effective way to improve seed yield in soybean.2020年と2021年に岡山大学農学部附属山陽圏フィールド科学センター（34°41ʼN, 133°55ʼE）でダイズの栽培試験を行った．アメリカ品種‘UA4805’ と日本品種‘あきまろ’ の2 品種を供試し，栽植密度を12.5 株 m-2（疎植，80 × 10 cm）と25 株m-2（密植，80 × 5 cm）の2 段階として，2020年5 月25日（早期）， 6 月29日（普通期）， 8 月3 日（晩期）に播種した．2021年は畦幅80 cm（広畦）と30 cm（狭畦），栽植密度12.5株m-2と25株m-2の2 段階で栽培した．子実収量は，2020年と2021年ともに‘あきまろ’ よりも‘UA4805’ の方が高かった．播種時期が遅いほど，粒/茎比が高くなった．両品種ともに疎植区に比べ密植区で乾物重が大きくなった．‘あきまろ’ は‘UA4805’ よりも乾物重は大きかったが，子実収量は低かった．一方，ʻUA4805ʼ は乾物重が小さかったが，節数，莢数，子実数が多く，子実収量が高かった．‘あきまろ’ は特に密植区において，倒伏程度が大きかった．粒/茎比は，いずれの試験区においてもʻ あきまろ’に比べ‘UA4805’ が著しく高かった．結莢率は‘UA4805’ が‘あきまろ’ より2 倍近く高かった．‘UA4805’ の子実収量が‘あきまろ’ に比べて高かったのは，結莢率，粒/茎比が高く，倒伏程度が小さかったことによるが，乾物生産は‘あきまろ’ の方が大きかった．晩期栽培の場合，子実収量を向上させるためには栽植密度を高くすることが推奨された．ダイズの子実収量を向上させるには，狭畦栽培が効果的であった

Cyclotron resonance of correlated electrons in semiconductor heterostructures

The cyclotron resonance absorption of two-dimensional electrons in semiconductor heterostructures in high magnetic fields is investigated. It is assumed that the ionized impurity potential is a dominant scattering mechanism, and the theory explicitly takes the Coulomb correlation effect into account through the Wigner phonons. The cyclotron resonance linewidth is in quantitative agreement with the experiment in the Wigner crystal regime at T=4.2K. Similar to the cyclotron resonance theory of the charge density waves pinned by short-range impurities, the present results for the long-range scattering also show the doubling of the resonance peaks. However, unlike the case of the charge density waves, our theory gives the pinning mode independent of the bulk compressibility of the substrate materials.Comment: 6 pages, 5 figure

Geochemical and radiogenic isotopic signatures of granitic rocks in Chanthaburi and Chachoengsao provinces, southeastern Thailand : Implications for origin and evolution

The Chanthaburi, Pliew, Klathing, Khao Cha Mao, and Khao Hin Son granitic bodies in Chanthaburi and Chachoengsao provinces in southeastern Thailand, which are located on the southwestern side of the Mae Ping Fault and eastern side of the Klaeng Fault, were investigated. In this study, magnetic susceptibility measurements, whole-rock chemical composition and Nd-Sr isotope analyses, and zircon U-Pb dating were conducted on these granitic bodies. The surveyed granitic rocks are classified as I- to A-type granites, are of the ilmenite series, and show clearly negative Eu anomalies, which suggest they formed under reducing conditions. Nd-Sr isotope ratios indicate continental crust material involvement in the formation of these granite bodies. The magnetic and geochemical signatures are similar to those of granite bodies in southwestern Cambodia. The study area is thus considered an extensional area of southwestern Cambodia, corresponding to the Sukhothai Zone (the Chanthaburi-Kampong Chhnang Zone). Zircon U-Pb dating yields ages of 208–214 Ma (the Late Triassic) for granite bodies except for the Khao Cha Mao granitic body, which dates to 55 Ma. The former age corresponds to the collision time of the Sibumasu and Indochina terranes, and the latter age is likely related to the collision time of the Indian and Eurasian continents

Multi-channel SPR biosensor based on PCF for multi-analyte sensing applications

This paper presents a theoretical investigation of a novel holey fiber (Photonic Crystal Fiber (PCF)) multi-channel biosensor based on surface plasmon resonance (SPR). The large gold coated micro fluidic channels and elliptical air hole design of our proposed biosensor aided by a high refractive index over layer in two channels enables operation in two modes; multi analyte sensing and self-referencing mode. Loss spectra, dispersion and detection capability of our proposed biosensor for the two fundamental modes (HE x 11 and HE y 11 ) have been elucidated using a Finite Element Method (FEM) and Perfectly Matching Layers (PML)

Nature of magnetic coupling between Mn ions in as-grown Ga1−x_{1-x}Mnx_{x}As studied by x-ray magnetic circular dichroism

The magnetic properties of as-grown Ga$_{1-x}$Mn$_{x}$As have been investigated by the systematic measurements of temperature and magnetic field dependent soft x-ray magnetic circular dichroism (XMCD). The {\it intrinsic} XMCD intensity at high temperatures obeys the Curie-Weiss law, but residual spin magnetic moment appears already around 100 K, significantly above Curie temperature ($T_C$), suggesting that short-range ferromagnetic correlations are developed above $T_C$. The present results also suggest that antiferromagnetic interaction between the substitutional and interstitial Mn (Mn$_{int}$) ions exists and that the amount of the Mn$_{int}$ affects $T_C$.Comment: 4 pages, 4 figure

Invariant varieties of periodic points for some higher dimensional integrable maps

By studying various rational integrable maps on $\mathbf{\hat C}^d$ with $p$ invariants, we show that periodic points form an invariant variety of dimension $\ge p$ for each period, in contrast to the case of nonintegrable maps in which they are isolated. We prove the theorem: {\it `If there is an invariant variety of periodic points of some period, there is no set of isolated periodic points of other period in the map.'}Comment: 24 page

Photo-excitation band-structure engineering of 2H-NbSe2_2 probed by time- and angle-resolved photoemission spectroscopy

We investigated the nonequilibrium electronic structure of 2H-NbSe$_2$ by time- and angle-resolved photoemission spectroscopy. We find that the band structure is distinctively modulated by strong photo-excitation, as indicated by the unusual increase in the photoelectron intensities around E$_F$. In order to gain insight into the observed photo-induced electronic state, we performed DFT calculations with modulated lattice structures, and found that the variation of the Se height from the Nb layer results in a significant change in the effective mass and band gap energy. We further study the momentum-dependent carrier dynamics. The results suggest that the relaxation is faster at the K-centered Fermi surface than at the $\Gamma$-centered Fermi surface, which can be attributed to the stronger electron-lattice coupling at the K-centered Fermi surface. Our demonstration of band structure engineering suggests a new role for light as a tool for controlling the functionalities of solid-state materials.Comment: 7 pages, 5 figure

Detection of spin bias in four-terminal quantum-dot ring

In this work, we show that in a four-quantum-dot ring, via introducing a local Rashba spin-orbit interaction the spin bias in the transverse terminals can be detected by observing the charge currents in the longitudinal probes. It is found that due to the Rashba interaction, the quantum interference in this system becomes spin-dependent and the opposite-spin currents induced by the spin bias can present different magnitudes, so charge currents emerge. Besides, the charge currents rely on both the magnitude and spin polarization direction of the spin bias. It is believed that this method provides an electrical but practical scheme to detect the spin bias (or the spin current).Comment: 6 pages, 5 figure

ELECTRONIC STRUCTURE OF FeSi

The full set of high-energy spectroscopy measurements including X-ray photoelectron valence band spectra and soft X-ray emission valence band spectra of both components of FeSi (Fe K_beta_5, Fe L_alpha, Si K_beta_1,3 and Si L_2,3) are performed and compared with the results of ab-initio band structure calculations using the linearized muffin-tin orbital method and linearized augmented plane wave method.Comment: 11 pages + 3 PostScript figures, RevTex3.0, to be published in J.Phys.:Cond.Matte