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951.
J. Moraczewski J. Gautron A. Duma A. Le Moigne I. Martelly 《Cellular and molecular life sciences : CMLS》1991,47(3):241-245
Summary The relationship between the activity of protein kinase C (PKC) and muscle innervation was explored in the rat sternomastoid muscle (SM) from day 18 of gestation (E18) to adult age. Between E18 and birth, PKC activity rose 5-fold, and during the day after birth, diminished to a level characteristic of the mature muscle. The rise chiefly occurred in the neural part of the muscle, in both the membrane and the cytosol fractions. Between E18 and day 5 after birth, the ratios of membrane to cytosol PKC activity rose from 0.5 to 10 and 3 respectively in the neural and aneural parts of the muscle. Denervation of adult SM reduced PKC activity by half in the membrane fraction of the neural part but did not significantly change it in the membrane or cytosol fractions of the aneural parts. These results suggest that innervation plays an important part in determining the level of PKC activity in muscle. 相似文献
952.
Alan M. Barstow 《Systemic Practice and Action Research》1990,3(4):339-355
This paper discusses Interactive Planning and Management (Ackoff, 1981) and its value for managing creatively and effectively in conflict situations. The author compares and contrasts the approach with alternative dispute resolution (ADR) including mediation-, negotiation-, and litigation-based processes and argues that the current methods developed in the ADR field are inadequate in their design to accommodate four considerations: (1) the interrelationships of problems facing organizations in conflict, (2) the accelerating rate of change in society, (3) the purposefulness of the parts of social systems as well as of the systems themselves, and (4) the effects of organizations' actions on their environment. The paper presents two cases in which Interactive Planning and Management was used to transform organizational decision making and structure. 相似文献
953.
Heat generation by electric current, which is ubiquitous in electronic devices and circuits, raises energy consumption and will become increasingly problematic in future generations of high-density electronics. The control and re-use of heat are therefore important topics for existing and emerging technologies, including spintronics. Recently it was reported that heat flow within a ferromagnet can produce a flow of spin angular momentum-a spin current-and an associated voltage. This spin Seebeck effect has been observed in metallic, insulating and semiconductor ferromagnets with temperature gradients across them. Here we describe and report the demonstration of Seebeck spin tunnelling-a distinctly different thermal spin flow, of purely interfacial nature-generated in a tunnel contact between electrodes of different temperatures when at least one of the electrodes is a ferromagnet. The Seebeck spin current is governed by the energy derivative of the tunnel spin polarization. By exploiting this in ferromagnet-oxide-silicon tunnel junctions, we observe thermal transfer of spins from the ferromagnet to the silicon without a net tunnel charge current. The induced spin accumulation scales linearly with heating power and changes sign when the temperature differential is reversed. This thermal spin current can be used by itself, or in combination with electrical spin injection, to increase device efficiency. The results highlight the engineering of heat transport in spintronic devices and facilitate the functional use of heat. 相似文献
954.
Li W Bloom JS Podsiadlowski P Miller AA Cenko SB Jha SW Sullivan M Howell DA Nugent PE Butler NR Ofek EO Kasliwal MM Richards JW Stockton A Shih HY Bildsten L Shara MM Bibby J Filippenko AV Ganeshalingam M Silverman JM Kulkarni SR Law NM Poznanski D Quimby RM McCully C Patel B Maguire K Shen KJ 《Nature》2011,480(7377):348-350
Type Ia supernovae are thought to result from a thermonuclear explosion of an accreting white dwarf in a binary system, but little is known of the precise nature of the companion star and the physical properties of the progenitor system. There are two classes of models: double-degenerate (involving two white dwarfs in a close binary system) and single-degenerate models. In the latter, the primary white dwarf accretes material from a secondary companion until conditions are such that carbon ignites, at a mass of 1.38 times the mass of the Sun. The type Ia supernova SN 2011fe was recently detected in a nearby galaxy. Here we report an analysis of archival images of the location of SN 2011fe. The luminosity of the progenitor system (especially the companion star) is 10-100 times fainter than previous limits on other type Ia supernova progenitor systems, allowing us to rule out luminous red giants and almost all helium stars as the mass-donating companion to the exploding white dwarf. 相似文献
955.
Seibert MM Ekeberg T Maia FR Svenda M Andreasson J Jönsson O Odić D Iwan B Rocker A Westphal D Hantke M DePonte DP Barty A Schulz J Gumprecht L Coppola N Aquila A Liang M White TA Martin A Caleman C Stern S Abergel C Seltzer V Claverie JM Bostedt C Bozek JD Boutet S Miahnahri AA Messerschmidt M Krzywinski J Williams G Hodgson KO Bogan MJ Hampton CY Sierra RG Starodub D Andersson I Bajt S Barthelmess M Spence JC Fromme P Weierstall U Kirian R Hunter M Doak RB Marchesini S Hau-Riege SP Frank M 《Nature》2011,470(7332):78-81
X-ray lasers offer new capabilities in understanding the structure of biological systems, complex materials and matter under extreme conditions. Very short and extremely bright, coherent X-ray pulses can be used to outrun key damage processes and obtain a single diffraction pattern from a large macromolecule, a virus or a cell before the sample explodes and turns into plasma. The continuous diffraction pattern of non-crystalline objects permits oversampling and direct phase retrieval. Here we show that high-quality diffraction data can be obtained with a single X-ray pulse from a non-crystalline biological sample, a single mimivirus particle, which was injected into the pulsed beam of a hard-X-ray free-electron laser, the Linac Coherent Light Source. Calculations indicate that the energy deposited into the virus by the pulse heated the particle to over 100,000?K after the pulse had left the sample. The reconstructed exit wavefront (image) yielded 32-nm full-period resolution in a single exposure and showed no measurable damage. The reconstruction indicates inhomogeneous arrangement of dense material inside the virion. We expect that significantly higher resolutions will be achieved in such experiments with shorter and brighter photon pulses focused to a smaller area. The resolution in such experiments can be further extended for samples available in multiple identical copies. 相似文献
956.
Jirawatnotai S Hu Y Michowski W Elias JE Becks L Bienvenu F Zagozdzon A Goswami T Wang YE Clark AB Kunkel TA van Harn T Xia B Correll M Quackenbush J Livingston DM Gygi SP Sicinski P 《Nature》2011,474(7350):230-234
Cyclin D1 is a component of the core cell cycle machinery. Abnormally high levels of cyclin D1 are detected in many human cancer types. To elucidate the molecular functions of cyclin D1 in human cancers, we performed a proteomic screen for cyclin D1 protein partners in several types of human tumours. Analyses of cyclin D1 interactors revealed a network of DNA repair proteins, including RAD51, a recombinase that drives the homologous recombination process. We found that cyclin D1 directly binds RAD51, and that cyclin D1-RAD51 interaction is induced by radiation. Like RAD51, cyclin D1 is recruited to DNA damage sites in a BRCA2-dependent fashion. Reduction of cyclin D1 levels in human cancer cells impaired recruitment of RAD51 to damaged DNA, impeded the homologous recombination-mediated DNA repair, and increased sensitivity of cells to radiation in vitro and in vivo. This effect was seen in cancer cells lacking the retinoblastoma protein, which do not require D-cyclins for proliferation. These findings reveal an unexpected function of a core cell cycle protein in DNA repair and suggest that targeting cyclin D1 may be beneficial also in retinoblastoma-negative cancers which are currently thought to be unaffected by cyclin D1 inhibition. 相似文献
957.
Role of YAP/TAZ in mechanotransduction 总被引:3,自引:0,他引:3
Dupont S Morsut L Aragona M Enzo E Giulitti S Cordenonsi M Zanconato F Le Digabel J Forcato M Bicciato S Elvassore N Piccolo S 《Nature》2011,474(7350):179-183
958.
Solar activity effects of the ionosphere: A brief review 总被引:13,自引:0,他引:13
Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar
activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics, providing information essential
to understanding the variations in the ionosphere and its processes. Selected recent studies on solar activity effects of
the ionosphere are briefly reviewed in this report. This report focuses on (1) observations of solar irradiance at X-ray and
extreme ultraviolet wavelengths and the outstanding problems of solar proxies, in the view of ionospheric studies, (2) new
findings and improved representations of the features of the solar activity dependence of ionospheric key parameters and the
corresponding physical processes, (3) possible phenomena in the ionosphere under extremely high and low solar activity conditions
that are unique, as indicated by historical solar datasets and the deep solar minimum of solar cycle 23/24, and (4) statistical
studies and model simulations of the ionosphere response to solar flares. The above-mentioned studies provide new clues for
comprehensively explaining basic processes in the ionosphere and improving the prediction capability of ionospheric models
and related applications. 相似文献
959.
诉讼调解在当今构建和谐社会的政治语境下,已经成为一种司法政策导向,调解结案更多地成为民事司法的目的而不是纠纷解决的方式。诉讼调解中实体法和程序法的双重软化凸显了检察机关进行诉讼调解检察监督的必要性。诉讼调解检察监督并不违背合法、自愿调解原则,并不干涉法院的独立审判。规范诉讼调解检察监督的提起范围和提起方式则成为理论界和实务界必须认真审视的课题。 相似文献
960.