Gravitational wave background from neutrino-driven gamma-ray bursts

We study cosmic microwave background (CMB) secondary anisotropies produced by inhomogeneous reionization by means of cosmological simulations coupled with the radiative transfer code crash . The reionization history is consistent with the Wilkinson Microwave Anisotropy Probe Thomson optical depth determination. We find that the signal arising from this process dominates over the primary CMB component for   l ≳ 4000  and reaches a maximum amplitude of   l ( l + 1) C_l /2π≃ 1.6 × 10⁻¹³  on arcmin scales (i.e. l as large as several thousands). We then cross-correlate secondary CMB anisotropy maps with neutral hydrogen 21-cm line emission fluctuations obtained from the same simulations. The two signals are highly anticorrelated on angular scales corresponding to the typical size of H  ii regions (including overlapping) at the 21-cm map redshift. We show how the CMB/21-cm cross-correlation can be used: (i) to study the nature of the reionization sources; (ii) to reconstruct the cosmic reionization history; (iii) to infer the mean cosmic ionization level at any redshift. We discuss the feasibility of the proposed experiment with forthcoming facilities.     

Sweeping-magnetic-twist mechanism for the acceleration of jets in the solar atmosphere

A magnetodynamic mechanism for the acceleration of jets in the solar atmosphere (surges, Brueckner's EUV jets, and so on) is proposed, and a 2.5-dimensional MHD simulation is performed to show how this mechanism operates in the situation of the chromosphere-corona region of the solar atmosphere. It is seen from the result of simulation that together with the release of the magnetic twist, e.g., into a reconnected open flux tube, the mass in the high density twisted loop is driven out into the open flux tube due both to the pinch effect progressing with the packet of the magnetic twist into the open flux tube, and to the j × B force at the front of the packet of the unwinding twist in the off-axis part of the tube. The former, the progressing pinch, is accompanied by an accelerated hot blob, while the latter, the unwinding front of the magnetic twist, drives a cool cylindrical flow, both with velocities of the order of the local Alfvén velocity. One of the characteristic properties of the jet in our model is that the jet, consisting of hot core and cool sheath, has a helical velocity field in it, explaining the thus-far unexplained observed feature.The sudden release of the magnetic twist into an open flux tube is most likely to be due to the reconnection between a twisted loop and the open flux tube. The mass is driven out in the relaxation process of the magnetic twist from the twisted loop to the open flux tube.     

Variable microstructure of peridotite samples from the southern Mariana Trench: Evidence of a complex tectonic evolution

We retrieved samples of peridotite from a dredge haul (KH92-1-D2) collected during Cruise KH92-1 undertaken by the research vessel (R/V) Hakuho in 1992 at the landward trench slope of the southern Mariana Trench (11°41.16′N, 143°29.62′E; depth 6594–7431 m), which is the deepest ocean in the world. Ten of 30 retrieved samples possessed both a foliation and lineation, as assessed from 46 thin sections of various orientations and observations of hand samples. The samples showed marked variation in microstructure, ranging from coarse (> 5 mm) equigranular and intensely elongated textures to finer (< 1 mm) porphyroclastic and fine-grained equigranular textures. Olivine fabrics also varied among the different samples, with (010)[100] and (010)[001] patterns (termed A- and B-type, respectively) observed in samples with coarse textures and no clear patterns observed in samples with fine textures. Even though the peridotite samples were retrieved from a single dredge site, some contain primary tectonic microstructures and some contain secondary microstructures. Recent bathymetric and topographic analyses indicate that the lithosphere in this region is as thin as 20 km. Such a thin lithosphere may have been intensely deformed, even perhaps in the ductile regime, during fore-arc extension; consequently, the observed variations in microstructure within the peridotite samples probably reflect the complex tectonic evolution of the southern Mariana region.     

Geochemistry and origin of Archean volcanic rocks from the Upper Keewatin assemblage (ca 2.7 Ga), Lake of the Woods Greenstone Belt, Western Wabigoon Subprovince, Superior Province, Canada

Abstract   Volcanic rocks from the Upper Keewatin assemblage ( ca 2720 Ma) were geochemically classified into five groups; komatiites, tholeiitic rocks having near-flat primitive mantle-normalized abundance patterns, Nb-enriched basalts and andesites (NEBA) plus normal calc-alkaline (NCA) rocks, adakites and shoshonites. The adakites having [La/Yb]_N >30 and <30 were probably derived from felsic magmas formed by partial melting of a subducted slab at relatively greater and smaller depths, respectively. Ascending adakite magmas, by interaction with the overlying mantle wedge, decreased in Al₂O₃ / Y ratio and selectively lost high-field strength elements, thereby forming mantle sources for both NEBA + NCA and shoshonite magmas. Under the influence of a mantle plume, the source of komatiites, the NEBA + NCA magmas were generated from that part of the mantle wedge metasomatized by adakite magmas having [La / Yb]_N <30, and tholeiitic magmas from unmetasomatized part of the same mantle wedge. Magmas of both adakites having [La / Yb]_N >30 and shoshonites were generated in a normal Archean Arc system setting.     

Geochemical and Microbiological Analysis of Sambe Hot Springs,Shimane Prefecture,Japan

Microbiological contribution to the formation of the manganese deposits in Sambe hot springs, Shimane, was investigated in combination with water chemistry, characterization of sediments and microbial community structure. Analysis of bacterial and fungal community structure based on DNA extracted from a Mn‐oxidizing enrichment culture indicated close matches with Pseudomonas putida, Phoma sp. and Plectosphaerella cucumerina, all Mn‐oxidizing microorganisms. These sediments were poorly crystalline and formed at neutral pH values, which is characteristic of biogenic precipitates. The EPMA results demonstrated a positive correlation between Mn and Ba contents in well‐crystalline Mn oxide grains. Substantial Ba contents were observed inside Mn oxide grains. These findings indicated that Ba contents in sediments are influenced by not only aqueous Ba²⁺ concentrations but also crystallinity of biogenic birnessite. Barium would be incorporated in birnessite during biomineralization.     

Comparison of the lethal effect of CO2 and acidification on red sea bream (Pagrus major) during the early developmental stages

To compare the acute toxicity of CO(2)- and HCl-acidified seawater, eggs and larvae of a marine fish, Pagrus major, were exposed to seawater equilibrated with CO(2)-enriched gas mixtures (CO(2)=5% or 10%, O(2)=20.95% balanced with N(2)) or seawater acidified with 1 N HCl at two pH levels (pH 6.2 (=5% CO(2)) and 5.9 (=10% CO(2))) for 6 h (eggs) or 24 h (larvae). Mortalities of eggs were 85.8% (CO(2)) and 3.6% (HCl) at pH 6.2, and 97.4% (CO(2)) and 0.9% (HCl) at pH 5.9, while those of larvae were 61.2% (CO(2)) and 1.6% (HCl) at pH 6.2, and 100% (CO(2)) and 5.0% (HCl) at pH 5.9. Thus, previous research on the effects of acidified seawater on marine organisms, as a substitute for CO(2), has largely underestimated the toxic effects of CO(2).     

Reinventing rice husk ash: derived NaX zeolite as a high-performing CO<Subscript>2</Subscript> adsorbent

In this work, rice husk ash was used as silica source to synthesize NaX zeolite potentially suitable for CO₂ adsorption. The produced material, denoted NaX-RHA, was characterized employing X-ray diffraction, scanning electron microscopy and gas adsorption porosimetry, in order to verify the occurred production of well-crystallized NaX zeolite with a significant degree of purity. CO₂ adsorption isotherms on NaX-RHA were volumetrically evaluated in the 298–348 K temperature range up to standard pressure, revealing performances that are higher than those reported for commercial similar substrates. The experimental data regarding CO₂ adsorption on NaX-RHA were very satisfyingly fitted by the semiempirical Sips model. Analyzing the best fitting values of model parameters allowed to conclude that the synthesized adsorbent could be quite suitable for applications like CO₂ capture from flue gas.     

Petrology and shock history of the first depleted-like poikilitic shergottite Asuka 12325

Asuka (A) 12325 is the first poikilitic shergottite having a depleted pattern in light rare earth elements (REE). Compared with known poikilitic shergottites, A 12325 has smaller but more abundant pyroxene oikocrysts with remarkable Fe-rich pigeonite rims, indicating that A 12325 cooled relatively faster at a shallower part of the crust. The redox condition (logfO₂ = IW + 0.6-IW + 1.7) and Fe-rich chemical compositions of each mineral in A 12325 are close to enriched shergottites. The intermediate shergottites could not form by a simple mixing between parent magmas of A 12325 and enriched shergottites. Although A 12325 contains various high-pressure minerals such as majorite and ringwoodite, plagioclase is only partly maskelynitized. Therefore, the maximum shock pressure may be within 17–22 GPa. Thermal conduction and ringwoodite growth calculation around a shock vein revealed that the shock dwell time of A 12325 is at least 40 ms. The weaker shock pressure and longer shock dwell time in A 12325 may be attained by an impact event similar to those of nakhlites and Northwest Africa (NWA) 8159. Such a weak shock ejection event may be as common on Mars as a severe shock event recorded in shergottites. Alteration of sulfide observed in A 12325 may imply the presence of magmatic fluid in its reservoir on Mars. A 12325 expands a chemical variety of Martian rocks and has a unique shock history among poikilitic shergottites while A 12325 also implies that poikilitic shergottites are common rocks on Mars regardless of their sources.