Evidence for iron whiskers near the galactic centre

It is shown that ~ 10² M of iron in the form of long slender whiskers, expelled from supernovae, can explain an observed deficit of line emission in the 157.7µm C II line and in the 205µm N II line from the galactic centre region.     

Frequency selective surfaces for radio astronomy

Frequency selective surfaces (FSSs) with the Jerusalem-cross array configuration have been developed for simultaneous observations of radio astronomical sources at the 40GHz and 80GHz bands. For supporting material, PET(polyethylene terephthalate: 200×220mm large, 12m thick, permittivity 3.0) was used, and copper was used for the conducting array. The measured characteristics were in good agreement with the calculated ones. The fabricated FSS has low insertion losses of less than 0.2dB and little distortion of polarization for each band. The characteristics of the developed FSS satisfy radio astronomical requirements.     

Microtopographic analysis of plant distribution in polar desert

We suggest methods for the analysis of the spatial distribution of plant species in a research area divided into a quadrat lattice. In particular, information about the topography and the spaces without plants is used for the analysis. At sites with a homogeneous substratum, we classify the topography by whether a target grid is concave or convex with respect to a standard surface of altitude. At other sites, we classify the topography according to whether the grid is located at the edge of rock and/or at a water pool. Information about the topography and the plant existence is used for constructing 2 × 2 contingency tables. In order to determine the strength of dependence between the topography and plant existence, the Akaike information criterion (AIC) is used. The methods are applied to data of the microtopography and distribution of mosses in continental Antarctica.     

MIS11–19 pollen stratigraphy from the 250-m Choshi core, northeast Boso Peninsula, central Japan: Implications for the early/mid-Brunhes (400–780 ka) climate signals

Abstract   The 250-m Choshi core (CHOSHI-1), drilled from hemipelagic muds of the Inubo Group, has been physically, geochemically and tephrochronologically analyzed back to 1 Ma. We provide pollen results for the 19–169 m section of the core (400–780 ka) bracketed by the marker tephra Ty1 (equivalent to J4) and the Brunhes–Matuyama paleomagnetic boundary. The results show good agreement with the corresponding oxygen isotope (δ¹⁸O) profile, with high δ¹⁸O intervals dominated by boreal conifers Picea , Abies , Pinus (subgen. Haploxylon ) and Tsuga ( diversifolia ), whereas low δ¹⁸O intervals are dominated by temperate conifers Cryptomeria , Taxaceae-Cephalotaxaceae-Cupressaceae and Sciadopitys . In order to confirm pollen-climate relations for the relevant taxa, a modern surface pollen dataset for the Japanese archipelago was consulted. In this analysis, the ratios of Cryptomeria / Picea and temperate/boreal conifers serve as proxies for the 100-kyr glacial/interglacial cycle during the Middle Pleistocene. Distinct signals for marine isotope stages (MIS) 11, 12, 13–15, 16, 17 and 18–19 are recognized in accordance with the tephrochronology and δ¹⁸O of the same core. Application of the criteria to an independent pollen record from Lake Biwa provides an integrated pollen stratigraphy for mid-latitude Japan during the past 800 ky. Some degree of uncertainty remains in the chronology of the MIS13–15 interval, relating to the uncertainty in the eruption age of widespread tephra Ks11.     

Is the plastic flow uniformly distributed below the seismogenic region?

We compared the cutoff depth of seismicity in and around the Nojima fault broken by the 1995 Kobe earthquake occurring in intraplate Japan with the brittle–ductile transition depth of the widely accepted strength profile model of the crust. We successfully determined the temperature profile from borehole measurements, since almost the same geothermal gradients were observed at two boreholes located about 4 km apart from each other, and the thermal conductivity and heat production were also measured by taking numerous core samples. We found that the cutoff depth was much deeper than the transition depth under the assumption that wet granite is deformed at a strain rate of 3×10⁻¹⁵ s⁻¹. This small strain rate implies, however, that plastic flow is uniformly distributed below the seismogenic region. When the strain rate is assumed to be greater than 10⁻¹³ s⁻¹, the cutoff depth can be attributed to the transition depth. This suggests that deformation is localized in a narrow fault zone below the seismogenic region, even in the intraplate region.     

Forced convection accompanying wind waves

Wind-wave tunnel experiments reveal, by use of techniques of the flow visualization, that wind waves are accompanied by the wind drift surface current with large velocity shear and with horizontal variation of velocity relative to the wave profile. The surface current converges from the crest to a little leeward face of the crest, making a downward flow there, even though the wave is not breaking. Namely, wind waves are accompanied by forced convections relative to the crests of the waves. Since the location of the convergence and the downward flow travels on the water surface as the crest of the wave propagates, the motion as a whole is characterized by turbulent structure as well as by the nature of water-surface waves. In this meaning, the term of real wind waves is proposed in contrast with ordinary water waves. The study of real wind waves will be essential in future development of the study of wind waves.     

Seasonal Patterns of Vertical Distribution between Meiofaunal Groups in Relation to Phytodetritus Deposition in the Bathyal Sagami Bay, Central Japan

Temporal changes in the vertical distribution of metazoan meiofaunal groups were examined at a bathyal site (depth 1450 m) in Sagami Bay from December 1996 to August 1998. Among major meiofaunal groups, the vertical distributions of copepods (adults and copepodites), and kinorhynchs changed seasonally and they concentrated in the shallower part in the sediment profile when CPE concentrations were higher. Seasonal changes in the vertical distributions of ovigerous females and nauplii of copepods were not related to CPE concentrations, but related to that of total copepods. On the other hand, nematodes, ostracods, and polychaetes did not show seasonal migrations. These results suggest that there is a difference in the response to the sedimentation of organic matter between metazoan meiofaunal taxa.     

Hg, Zn and Cu levels in the muscle and liver of tiger sharks (Galeocerdo cuvier) from the coast of Ishigaki Island, Japan: relationship between metal concentrations and body length

We analyzed Hg, Zn and Cu concentrations in the liver and muscle of tiger sharks (Galeocerdo cuvier) from the coast of Ishigaki Island, Japan. The Hg concentration in the muscle increased proportionally with body length in the tiger sharks, whereas that in the liver increased rapidly after maturity (defined by a length of over 2.7 m). Muscle Hg levels were higher than liver concentrations in immature sharks, with the inverse trend observed in mature sharks. Notably, the Zn and Cu concentrations in the liver tended to decrease with increasing body length. This rapid increase in hepatic Hg concentration concurrent with the onset of maturity in sharks may result from the continuous intake of Hg via food and the slower growth of mature sharks. The high concentrations of the essential metals Zn and Cu in immature sharks may be explained by the physiological demands related to rapid growth.     

Relaxation method for pounding action between adjacent buildings at expansion joint

Earthquake‐induced structural pounding frequently causes serious damage to buildings, particularly at the expansion joint (hereafter, EXPJ) between adjacent buildings. Because the EXPJ width in existing reinforced concrete buildings is usually very small, typically about 5 cm for school buildings in Japan, collision avoidance cannot be achieved by seismic retrofitting. This paper presents an experimental investigation into an effective method for reducing severe structural damage due to pounding at the EXPJ between narrowly separated buildings. The method involves inserting a shock‐absorbing material such as rubber into the EXPJ gap. The efficiency of the proposed method is evaluated by laboratory shaking tests using two model buildings. Furthermore, a lumped mass model is used to carry out a collision analysis in order to numerically investigate the influence of such a shock‐absorbing material. Both the numerical and experimental results confirm the effectiveness of the proposed approach. The validity of the proposed method is also demonstrated by numerical simulation of adjacent 10‐story steel buildings with an EXPJ width of 5 cm. The force, acceleration and velocity produced by earthquake‐induced structural pounding are found to be remarkably mitigated by inserting a soft shock‐absorbing material into the EXPJ gap. Copyright © 2014 John Wiley & Sons, Ltd.     

Petrological characteristics and volatile content of magma from the 2000 eruption of Miyakejima Volcano, Japan

Among the series of eruptions at Miyakejima volcano in 2000, the largest summit explosion occurred on 18 August 2000. During this explosion, vesiculated bombs and lapilli having cauliflower-like shapes were ejected as essential products. Petrological observation and chemical analyses of the essential ejecta and melt inclusions were carried out in order to investigate magma ascent and eruption processes. SEM images indicate that the essential bombs and lapilli have similar textures, which have many tiny bubbles, crystal-rich and glass-poor groundmass and microphenocrysts of plagioclase, augite and olivine. Black ash particles, which compose 40% of the air-fall ash from the explosion, also have similar textures to the essential bombs. Whole-rock analyses show that the chemical composition of all essential ejecta is basaltic (SiO₂=51–52 wt%). Chemical analyses of melt inclusions in plagioclase and olivine phenocrysts indicate that melt in the magma had 0.9–1.9 wt% H₂O, <0.011 wt% CO₂, 0.04–0.17 wt% S and 0.06–0.1 wt% Cl. The variation in volatile content suggests degassing of the magma during ascent up to a depth of about 1 km. The ratio of H₂O and S content of melt inclusions is similar to that of volcanic gas, which has been intensely and continuously emitted from the summit since the end of August 2000, indicating that the 18 August magma is the source of the gas emission. Based on the volatile content of the melt inclusions and the volcanic gas composition, the initial bulk volatile content of the magma was estimated to be 1.6–1.9 wt% H₂O, 0.08–0.1 wt% CO₂, 0.11–0.17 wt% S and 0.06–0.07 wt% Cl. The basaltic magma ascended from a deeper chamber (10 km) due to decrease in magma density caused by volatile exsolution with pressure decrease. The highly vesiculated magma, which had at least 30 vol% bubbles, may have come into contact with ground water at sea level causing the large explosion of 18 August 2000.Editorial responsibility: S. Nakada, T. DuittAn erratum to this article can be found at