Plastid proteins crucial for symbiotic fungal and bacterial entry into plant roots

The roots of most higher plants form arbuscular mycorrhiza, an ancient, phosphate-acquiring symbiosis with fungi, whereas only four related plant orders are able to engage in the evolutionary younger nitrogen-fixing root-nodule symbiosis with bacteria. Plant symbioses with bacteria and fungi require a set of common signal transduction components that redirect root cell development. Here we present two highly homologous genes from Lotus japonicus, CASTOR and POLLUX, that are indispensable for microbial admission into plant cells and act upstream of intracellular calcium spiking, one of the earliest plant responses to symbiotic stimulation. Surprisingly, both twin proteins are localized in the plastids of root cells, indicating a previously unrecognized role of this ancient endosymbiont in controlling intracellular symbioses that evolved more recently.     

Up-grading of natural ilmenite ore by combining oxidation and acid leaching

Rutile (TiO₂) is heavily used in pigments and colorants, and the most abundant source of rutile is ilmenite. Upon oxidation of ilmenite, rutile can be formed with modest energy consumption; furthermore, after leaching, only a few byproducts are formed. Unfortunately, one drawback is the necessarily long oxidative process of typically used methods. In this study, we show that a fluidized bed reactor can be used to oxidize ilmenite ore to rapidly form rutile and pseudobrookite (Fe₂TiO₅) phases. Ilmenite was oxidized with 5vol% O₂ in Ar at temperatures of 1173 K or 1223 K and subsequently leached using a diluted H₂SO₄ solution to dissolve the pseudobrookite phase. The effects of acid concentration, temperature, and cooling rate after oxidation were investigated. We show that the ilmenite was rapidly oxidized to form rutile and pseudobrookite phases at 1173 and 1223 K in a 5vol% O₂/95vol% Ar environment within 40 min. The final maximum rutile yield was 84.2mol% after leaching in (1 + 1) H₂SO₄ solution at 393 K for 12 h.     

Effect of lower bainite/martensite/retained austenite triplex microstructure on the mechanical properties of a low-carbon steel with quenching and partitioning process

We present a study concerning Fe–0.176C–1.31Si–1.58Mn–0.26Al–0.3Cr (wt%) steel subjected to a quenching and partitioning (Q&P) process. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and tensile tests demonstrate that the microstructures primarily consist of lath martensite, retained austenite, lower bainite (LB), and a small amount of tempered martensite; moreover, few twin austenite grains were observed. In the microstructure, three types of retained austenite with different sizes and morphologies were observed: blocky retained austenite (~300 nm in width), film-like retained austenite (80–120 nm in width), and ultra- fine film-like retained austenite (30–40 nm in width). Because of the effect of the retained austenite/martensite/LB triplex microstructure, the specimens prepared using different quenching temperatures exhibit high ultimate tensile strength and yield strength. Furthermore, the strength effect of LB can partially counteract the decreasing strength effect of martensite. The formation of LB substantially reduces the amount of retained austenite. Analyses of the retained austenite and the amount of blocky retained austenite indicated that the carbon content is critical to the total elongation of Q&P steel.     

Low-frequency earthquakes in Shikoku, Japan, and their relationship to episodic tremor and slip

Non-volcanic seismic tremor was discovered in the Nankai trough subduction zone in southwest Japan and subsequently identified in the Cascadia subduction zone. In both locations, tremor is observed to coincide temporally with large, slow slip events on the plate interface downdip of the seismogenic zone. The relationship between tremor and aseismic slip remains uncertain, however, largely owing to difficulty in constraining the source depth of tremor. In southwest Japan, a high quality borehole seismic network allows identification of coherent S-wave (and sometimes P-wave) arrivals within the tremor, whose sources are classified as low-frequency earthquakes. As low-frequency earthquakes comprise at least a portion of tremor, understanding their mechanism is critical to understanding tremor as a whole. Here, we provide strong evidence that these earthquakes occur on the plate interface, coincident with the inferred zone of slow slip. The locations and characteristics of these events suggest that they are generated by shear slip during otherwise aseismic transients, rather than by fluid flow. High pore-fluid pressure in the immediate vicinity, as implied by our estimates of seismic P- and S-wave speeds, may act to promote this transient mode of failure. Low-frequency earthquakes could potentially contribute to seismic hazard forecasting by providing a new means to monitor slow slip at depth.     

Superflares on solar-type stars

Solar flares are caused by the sudden release of magnetic energy stored near sunspots. They release 10(29) to 10(32)?ergs of energy on a timescale of hours. Similar flares have been observed on many stars, with larger 'superflares' seen on a variety of stars, some of which are rapidly rotating and some of which are of ordinary solar type. The small number of superflares observed on solar-type stars has hitherto precluded a detailed study of them. Here we report observations of 365 superflares, including some from slowly rotating solar-type stars, from about 83,000 stars observed over 120 days. Quasi-periodic brightness modulations observed in the solar-type stars suggest that they have much larger starspots than does the Sun. The maximum energy of the flare is not correlated with the stellar rotation period, but the data suggest that superflares occur more frequently on rapidly rotating stars. It has been proposed that hot Jupiters may be important in the generation of superflares on solar-type stars, but none have been discovered around the stars that we have studied, indicating that hot Jupiters associated with superflares are rare.     

教育环境与儿童空间认知的城镇空间组成研究

文中从发展对儿童适宜的生活环境的观点出发来研究城市住房项目．该项研究是针对Makahari湾城镇的中层住宅及附属教育设施的公寓区展开的．文中采用草图来确定Makahari湾城镇中儿童生活与其环境之间的关系．1999年进行首次研究，接着在2003年进行第二次研究，此间该镇的建设有所发展．具体研究是利用儿童凭记忆点出的关于他们的住宅、学校、玩耍场地和其它较多被注意的场所的草图来进行的．在两次研究期间，该地区发生了许多实体环境的变化，这些变化能从儿童的草图的许多元素中反映出来．将这些草图中的变化加以对照、分析，并将环境的改变与儿童的空间认知的关系加以探讨，同时注意分析比较体现在草图中的区域范围。结果表明，儿童早期对目标物的了解能从Makahari湾的空间结构以及环境变化中得到增强，而两者都由方格的模式构成．经验、每目的生活以及对小学和儿童游戏场所的空间认知与儿童的生活环境息息相关．此项分析揭示了在一个发展中的住宅区中儿童对其生活环境的空间认知与其附属教育设施之间的关系．     

Determinant solutions of the nonautonomous discrete Toda equation associated with the deautonomized discrete KP hierarchy

##正## It is shown that the nonautonomous discrete Toda equation and its Backlund transformationcan be derived from the reduction of the hierarchy of the discrete KP equation and the discrete two-dimensionalToda equation.Some explicit examples of the determinant solutions of the nonautonomousdiscrete Toda equation including the Askey-Wilson polynomial are presented.Finally we discuss therelationship between the nonautonomous discrete Toda system and the nonautonomous discrete Lotka-Volterraequation.     

Molecular machinery for non-vesicular trafficking of ceramide

Synthesis and sorting of lipids are essential for membrane biogenesis; however, the mechanisms underlying the transport of membrane lipids remain little understood. Ceramide is synthesized at the endoplasmic reticulum and translocated to the Golgi compartment for conversion to sphingomyelin. The main pathway of ceramide transport to the Golgi is genetically impaired in a mammalian mutant cell line, LY-A. Here we identify CERT as the factor defective in LY-A cells. CERT, which is identical to a splicing variant of Goodpasture antigen-binding protein, is a cytoplasmic protein with a phosphatidylinositol-4-monophosphate-binding (PtdIns4P) domain and a putative domain for catalysing lipid transfer. In vitro assays show that this lipid-transfer-catalysing domain specifically extracts ceramide from phospholipid bilayers. CERT expressed in LY-A cells has an amino acid substitution that destroys its PtdIns4P-binding activity, thereby impairing its Golgi-targeting function. We conclude that CERT mediates the intracellular trafficking of ceramide in a non-vesicular manner.