1,239 research outputs found

    Design of a Cooper pair box electrometer for application to solid-state and astroparticle physics

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    We describe the design and principle of operation of a fast and sensitive electrometer operated at millikelvin temperatures, which aims at replacing conventional semiconducting charge amplifiers in experiments needing low back-action or high sensitivity. The electrometer consists of a Cooper Pair box (CPB) coupled to a microwave resonator, which converts charge variations to resonance frequency shifts. We analyze the dependence of the sensitivity on the various parameters of the device, and derive their optimization. By exploiting the nonlinearities of this electrometer, and using conventional nanofabrication and measurement techniques, a charge sensitivity of a few 107e/Hz10^{- 7} e / \sqrt{Hz} can be achieved which outperforms existing single charge electrometers.Comment: 13 pages, 7 figure

    Model of a multiverse providing the dark energy of our universe

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    It is shown that the dark energy presently observed in our universe can be regarded as the energy of a scalar field driving an inflation-like expansion of a multiverse with ours being a subuniverse among other parallel universes. A simple model of this multiverse is elaborated: Assuming closed space geometry, the origin of the multiverse can be explained by quantum tunneling from nothing; subuniverses are supposed to emerge from local fluctuations of separate inflation fields. The standard concept of tunneling from nothing is extended to the effect that in addition to an inflationary scalar field, matter is also generated, and that the tunneling leads to an (unstable) equilibrium state. The cosmological principle is assumed to pertain from the origin of the multiverse until the first subuniverses emerge. With increasing age of the multiverse, its spatial curvature decays exponentially so fast that, due to sharing the same space, the flatness problem of our universe resolves by itself. The dark energy density imprinted by the multiverse on our universe is time-dependent, but such that the ratio w=ϱ/(c2p)w{=}\varrho/(c^2p) of its mass density and pressure (times c2c^2) is time-independent and assumes a value 1+ϵ-1{+}\epsilon with arbitrary ϵ>0\epsilon{>}0. ϵ\epsilon can be chosen so small, that the dark energy model of this paper can be fitted to the current observational data as well as the cosmological constant model.Comment: 32 pages, 4 figure


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    (A) The DNA distribution of cells treated with bicyclol-AKT cDNA-, bicyclol-AKT cDNA+, bicyclol + AKT cDNA- and bicyclol + AKT cDNA+. The cDNA was transfected as mentioned in Methods. Then the cells were treated with bicyclol for 24 h (B) The DNA distribution of cells treated with bicyclol or/and LY294002 for 24 h. (C) The DNA distribution of cells treated with bicyclol or/and PD98059 for 24 h. (TIF 809 kb


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    Este trabajo estudia la función del silencio en la novela El monstruo del Manzanares, novela corta incluida en la colección La mojiganga del gusto (1641) de Andrés Sanz del Castillo. Esta novela posee constantes alusiones al silencio, las cuales, sumadas a la ausencia de diálogos que reproduzcan las voces de los personajes, nos llevan a considerar, más allá todavía, que el silencio configura un tema en sí mismo dentro de El monstruo de Manzanares y determina notoriamente el sentido final de la novela

    Evaluación de los factores determinantes del recuento de plaquetas en pacientes con cirrosis

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    Thrombocytopenia is considered one of the hallmarks of patients with cirrhosis. Several mechanisms have been implicated in the pathophysiology of thrombocytopenia in cirrhosis. Hypersplenism caused by splenomegay, classically regarded as an indirect marker of portal hypertension has been considered the main factor implicated [200]. Nevertheless, portal hypertension is best estimated by the hepatic venous pressure gradient (HVPG) [32, 189], although contradictory results have been reported regarding the association between HVPG and platelet count [195-197]. The identification of thrombopoietin (TPO), a growth factor that enhances the maturation of megakaryocytes and the release of platelets from the bone marrow, has shed new light on the physiolgy of platelets [217]. In normal conditions in adults, TPO is mainly produced in the liver [93, 96] and the circulating leves of platelets are controlled by a negative feedback mechanism [99], so there is an inverse relationship between the amount of circulating platelets, and the amount of TPO that can reach the bone marrow to stimulate thrombopoiesis. In liver cirrhosis perhaps a decreased syntehesis of TPO could be implicated in the development of thrombocytopenia. Controversial findings regarding the role of each mechanism in thrombocytopenia of liver cirrhosis have been reported [142, 146, 160-161, 184] and no study has simultaneously evaluated the influence of the different mechanisms including portal hypertension and TPO production nor whether their influence could change in different stages of the disease..

    Seasonal variations of gross primary production (GPP) at the two sites.

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    <p>GPP was averaged for each 8-day period according to time stamp of MODIS FPAR. Only “good” GPP values (at most, 25% of half-hourly GPP values gap-filled) are shown.</p

    Relationships between light use efficiency (LUE) and EF and AET/PET at the two sites.

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    <p>EF (evaporative fraction) is ratio of latent heat flux to available energy (LE+H); AET/PET is ratio of actual evapotranspiration to potential evapotranspiration, calculated using the Penman-Monteith equation.</p

    Pearson correlation analysis between 8-day averages or sums of LUE and environmental factors at each site.

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    <p>TS: typical steppe; DS: desert steppe; T<sub>min</sub>: minimum temperature (°C); T<sub>a</sub>: average temperature (°C); T<sub>s5</sub>: soil temperature at 5 cm depth (°C); VPD: vapor pressure deficit (kPa); SWC<sub>10</sub>: soil water content at 10 cm depth (m<sup>3</sup> m<sup>−3</sup>); AET: actual evapotranspiration (mm); PET: potential evapotranspiration calculated using Penman-Monteith equation (mm); EF: evaporative fraction; AET/PET: the ratio of actual evapotranspiration to potential evapotranspiration; PRECP, precipitation (mm).</p><p><i>R<sup>2</sup></i> is determination coefficient; <i>n</i> is sample number.</p>*<p><i>P</i><0.05;</p>**<p><i>P</i><0.01.</p

    Comparison of fraction of photosynthetically active radiation absorbed by plant canopy (FPAR) estimated from different sources in 2009 on the desert steppe.

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    <p>MODIS FPAR and MODIS EVI were directly downloaded as MOD15A2 and MOD13Q1 products. FPAR values based on green and total LAI were estimated using Beer-Lambert Law and corresponding LAI estimates.</p