Lack of exposed ice inside lunar south pole Shackleton Crater   总被引：2，自引：0，他引：2  

Haruyama J  Ohtake M  Matsunaga T  Morota T  Honda C  Yokota Y  Pieters CM  Hara S  Hioki K  Saiki K  Miyamoto H  Iwasaki A  Abe M  Ogawa Y  Takeda H  Shirao M  Yamaji A  Josset JL 《Science (New York, N.Y.)》2008,322(5903):938-939

The inside of Shackleton Crater at the lunar south pole is permanently shadowed; it has been inferred to hold water-ice deposits. The Terrain Camera (TC), a 10-meter-resolution stereo camera onboard the Selenological and Engineering Explorer (SELENE) spacecraft, succeeded in imaging the inside of the crater, which was faintly lit by sunlight scattered from the upper inner wall near the rim. The estimated temperature of the crater floor, based on the crater shape model derived from the TC data, is less than approximately 90 kelvin, cold enough to hold water-ice. However, at the TC's spatial resolution, the derived albedo indicates that exposed relatively pure water-ice deposits are not on the crater floor. Water-ice may be disseminated and mixed with soil over a small percentage of the area or may not exist at all.  相似文献   

Formation of a one-dimensional array of oxygen in a microporous metal-organic solid     

Kitaura R  Kitagawa S  Kubota Y  Kobayashi TC  Kindo K  Mita Y  Matsuo A  Kobayashi M  Chang HC  Ozawa TC  Suzuki M  Sakata M  Takata M 《Science (New York, N.Y.)》2002,298(5602):2358-2361

We report the direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the MEM (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements. The obtained MEM electron density revealed that van der Waals dimers of physisorbed O2 locate in the middle of nanochannels and form a one-dimensional ladder structure aligned to the host channel structure. The observed O-O stretching Raman band and magnetic susceptibilities are characteristic of the confined O2 molecules in one-dimensional nanochannels of CPL-1 (coordination polymer 1 with pillared layer structure).  相似文献   

Functional annotation of a full-length Arabidopsis cDNA collection   总被引：2，自引：0，他引：2  

Seki M  Narusaka M  Kamiya A  Ishida J  Satou M  Sakurai T  Nakajima M  Enju A  Akiyama K  Oono Y  Muramatsu M  Hayashizaki Y  Kawai J  Carninci P  Itoh M  Ishii Y  Arakawa T  Shibata K  Shinagawa A  Shinozaki K 《Science (New York, N.Y.)》2002,296(5565):141-145

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Chondrulelike objects in short-period comet 81P/Wild 2   总被引：1，自引：0，他引：1  

Nakamura T  Noguchi T  Tsuchiyama A  Ushikubo T  Kita NT  Valley JW  Zolensky ME  Kakazu Y  Sakamoto K  Mashio E  Uesugi K  Nakano T 《Science (New York, N.Y.)》2008,321(5896):1664-1667

The Stardust spacecraft returned cometary samples that contain crystalline material, but the origin of the material is not yet well understood. We found four crystalline particles from comet 81P/Wild 2 that were apparently formed by flash-melting at a high temperature and are texturally, mineralogically, and compositionally similar to chondrules. Chondrules are submillimeter particles that dominate chondrites and are believed to have formed in the inner solar nebula. The comet particles show oxygen isotope compositions similar to chondrules in carbonaceous chondrites that compose the middle-to-outer asteroid belt. The presence of the chondrulelike objects in the comet suggests that chondrules have been transported out to the cold outer solar nebula and spread widely over the early solar system.  相似文献   

A membrane-anchored protein kinase involved in Brassica self-incompatibility signaling     

Murase K  Shiba H  Iwano M  Che FS  Watanabe M  Isogai A  Takayama S 《Science (New York, N.Y.)》2004,303(5663):1516-1519

Self-incompatibility (SI) response in Brassica is initiated by haplotype-specific interactions between the pollen-borne ligand S locus protein 11/SCR and its stigmatic S receptor kinase, SRK. This binding induces autophosphorylation of SRK, which is then thought to trigger a signaling cascade that leads to self-pollen rejection. A recessive mutation of the modifier (m) gene eliminates the SI response in stigma. Positional cloning of M has revealed that it encodes a membrane-anchored cytoplasmic serine/threonine protein kinase, designated M locus protein kinase (MLPK). Transient expression of MLPK restores the ability of mm papilla cells to reject self-pollen, suggesting that MLPK is a positive mediator of Brassica SI signaling.  相似文献   

Gigantic photoresponse in 1/4-filled-band organic salt (EDO-TTF)2PF6     

Chollet M  Guerin L  Uchida N  Fukaya S  Shimoda H  Ishikawa T  Matsuda K  Hasegawa T  Ota A  Yamochi H  Saito G  Tazaki R  Adachi S  Koshihara SY 《Science (New York, N.Y.)》2005,307(5706):86-89

We report that the organic salt (EDO-TTF)2PF6 with 3/4-filled-band (1/4-filled in terms of holes), which forms an organic metal with strong electron and lattice correlation, shows a highly sensitive response to photoexcitation. An ultrafast, photoinduced phase transition from the insulator phase to the metal phase can be induced with very weak excitation intensity at near room temperature. This response makes the material attractive for applications in switching devices with room-temperature operation. The observed photo-induced spectroscopic change shows that this photoinduced phase transition process is caused by the cooperative melting of charge ordering assisted by coherent phonon generation.  相似文献   

Origin of the hard x-ray emission from the Galactic plane     

Ebisawa K  Maeda Y  Kaneda H  Yamauchi S 《Science (New York, N.Y.)》2001,293(5535):1633-1635

The Galactic plane is a strong emitter of hard x-rays (2 to 10 kiloelectron volts), and the emission forms a narrow continuous ridge. The currently known hard x-ray sources are far too few to explain the ridge x-ray emission, and the fundamental question of whether the ridge emission is ultimately resolved into numerous dimmer discrete sources or truly diffuse emission has not yet been settled. In order to obtain a decisive answer, using the Chandra X-ray Observatory, we carried out the deepest hard x-ray survey of a Galactic plane region that is devoid of known x-ray point sources. We detected at least 36 new hard x-ray point sources in addition to strong diffuse emission within a 17' by 17' field of view. The surface density of the point sources is comparable to that at high Galactic latitudes after the effects of Galactic absorption are considered. Therefore, most of these point sources are probably extragalactic, presumably active galaxies seen through the Galactic disk. The Galactic ridge hard x-ray emission is diffuse, which indicates omnipresence within the Galactic plane of a hot plasma, the energy density of which is more than one order of magnitude higher than any other substance in the interstellar space.  相似文献   

Genetics. Two genes link two distinct psychoses     

Sawa A  Snyder SH 《Science (New York, N.Y.)》2005,310(5751):1128-1129

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Simulation model of rainfed rice production on sloping land in northeast Thailand     

Kenji?SuzukiEmail author  Akira?Goto  Masakazu?Mizutani  Vichai?Sriboonlue 《Paddy and Water Environment》2003,1(2):91-97

In northeast Thailand, the rapid expansion of rainfed paddy fields has decreased the stability of rice production. This paper describes a model that computes rice production on the basis of the hydrologic conditions of rainfed paddy fields on hill slopes. The model well expressed the hydrologic processes, rice yield, and production at the study site. We simulated rice production as uphill paddy plots are abandoned, increasing catchment area, under various rainfall conditions. The simulation showed that rice yield and stability increase as uphill plots are abandoned, although the total rice production decreases. Thus, the effect of catchment size on rice production in each plot was quantified. The model proved to be useful for analyzing rainfed rice production under various land and water conditions.  相似文献   

Abiotic and biotic factors affecting recruitment variability of walleye pollock (Theragra chalcogramma) off the Pacific coast of Hokkaido,Japan     

Tetsuichiro Funamoto  Orio Yamamura  Tokihiro Kono  Tomonori Hamatsu  Akira Nishimura 《Fisheries Oceanography》2013,22(3):193-206

Abiotic and biotic factors affecting the recruitment variability of the Japanese Pacific stock (JPS) of walleye pollock (Theragra chalcogramma) were examined using a bivariate regression and multivariate combined model. Of the abiotic variables around Funka Bay (spawning ground), February sea surface temperature (SST) and wind direction index showed significant bivariate relationships with recruitment. February SST was positively related to recruitment, suggesting that warmer water temperature in February favors JPS recruitment. On the other hand, the relationship between February wind direction index and recruitment predicts high JPS recruitment under predominant northwest winds in February. For the biotic variables in the Doto area (nursery ground), significant and negative bivariate relationships with recruitment were observed for catch per unit effort of Kamchatka flounder (Atheresthes evermanni), Pacific cod (Gadus macrocephalus), and walleye pollock, implying an important impact of predation by these groundfishes on JPS recruitment. The overall model incorporating these abiotic and biotic factors successfully reproduced the variability in JPS recruitment. Temperature and wind conditions around the spawning ground along with predator condition in the nursery ground appear to play a dominant role in the recruitment dynamics of JPS. Based on these results and prior knowledge, we propose a new hypothesis to explain the processes controlling JPS recruitment.  相似文献