646 research outputs found
Do asset price fluctuations constitute a risk to growth in the major industrialised countries?
Asset price fluctuations give grounds for concern in the major industrialised countries. But to what extent do they affect economic growth? The answer to this question partly depends on householdsâ levels of debt and the structure of their financial wealth. We shall first summarise the different wealth effect estimates. This analysis shows that the impact of asset price fluctuations is more pronounced in the United States and the United Kingdom than in euro area countries. Asset price fluctuations in the United States appear to have an even greater impact on euro area growth than changes in household wealth within the euro area. Overall, outside of the United States and the United Kingdom, wealth effects are fairly limited, despite the existence of spillover effects transmitted through international trade and/or financial markets. Furthermore, these findings seem to be consistent with those obtained using other quantitative approaches that analyse the co-movements between business and financial cycles. They also conclude that, apart from in the United States, a high degree of dependence between economic growth and asset price fluctuations in the short term cannot be identified. We shall then provide an international comparison of the financial position of households (United States, Japan, United Kingdom, Germany, France and Italy). This analysis points to a certain degree of heterogeneity. In particular, the financial vulnerability of US and UK households, which have a larger appetite for debt and risky assets, is greater than that of households of the major euro area countries. In this context, it is not surprising that the shocks affecting asset prices have a more marked effect on household consumption and growth in the United States and the United Kingdom than in the major euro area countries or in Japan.
Investigation of Graded La2NiO4+ Cathodes to Improve SOFC Electrochemical Performance
Mixed ionic and electronic conducting MIEC oxides are promising materials for use as cathodes in solid oxide fuel cells SOFCs due to their enhanced electrocatalytic activity compared with electronic conducting oxides. In this paper, the MIEC oxide La2NiO4+ was prepared by the sol-gel route. Graded cathodes were deposited onto yttria-stabilized zirconia YSZ pellets by dip-coating, and electrochemical impedance spectroscopy studies were performed to characterize the symmetrical cell performance. By adapting the slurries, cathode layers with different porosities and thicknesses were obtained. A ceria gadolinium oxide CGO barrier layer was introduced, avoiding insulating La2Zr2O7 phase formation and thus reducing resistance polarization of the cathode. A systematic correlation between microstructure, composition, and electrochemical performance of these cathodes has been performed. An improvement of the electrochemical performance has been demonstrated, and a reduction in the area specific resistance ASR by a factor of 4.5 has been achieved with a compact interlayer of La2NiO4+ between the dense electrolyte and the porous La2NiO4+ cathode layer. The lowest observed ASR of 0.11 cm2 at 800Ă°C was obtained from a symmetrical cell composed of a YSZ electrolyte, a CGO interlayer, an intermediate compact La2NiO4+ layer, a porous La2NiO4+ electrode layer, and a current collection layer of platinum paste
Continuous macroscopic limit of a discrete stochastic model for interaction of living cells
In the development of multiscale biological models it is crucial to establish
a connection between discrete microscopic or mesoscopic stochastic models and
macroscopic continuous descriptions based on cellular density. In this paper a
continuous limit of a two-dimensional Cellular Potts Model (CPM) with excluded
volume is derived, describing cells moving in a medium and reacting to each
other through both direct contact and long range chemotaxis. The continuous
macroscopic model is obtained as a Fokker-Planck equation describing evolution
of the cell probability density function. All coefficients of the general
macroscopic model are derived from parameters of the CPM and a very good
agreement is demonstrated between CPM Monte Carlo simulations and numerical
solution of the macroscopic model. It is also shown that in the absence of
contact cell-cell interactions, the obtained model reduces to the classical
macroscopic Keller-Segel model. General multiscale approach is demonstrated by
simulating spongy bone formation from loosely packed mesenchyme via the
intramembranous route suggesting that self-organizing physical mechanisms can
account for this developmental process.Comment: 4 pages, 3 figure
Exponential Distribution of Locomotion Activity in Cell Cultures
In vitro velocities of several cell types have been measured using computer
controlled video microscopy, which allowed to record the cells' trajectories
over several days. On the basis of our large data sets we show that the
locomotion activity displays a universal exponential distribution. Thus, motion
resulting from complex cellular processes can be well described by an
unexpected, but very simple distribution function. A simple phenomenological
model based on the interaction of various cellular processes and finite ATP
production rate is proposed to explain these experimental results.Comment: 4 pages, 3 figure
Preparation of NiâYSZ thin and thick films on metallic interconnects as cell supports. Applications as anode for SOFC
In this work, we propose the preparation of a duplex anodic layer composed of both a thin (100 nm) and a thick film (10 lm) with NiâYSZ material. The support of this anode is a metallic substrate, which is the interconnect of the SOFC unit cell. The metallic support limits the temperature of thermal treatment at 800 C to keep a good interconnect mechanical behaviour and to reduce corrosion. We have chosen to elaborate anodic coatings by solâgel route coupled with dip-coating process, which are low cost techniques and allow working with moderate temperatures. Thin films are obtained by dipping interconnect substrate into a sol, and thick films into an optimized slurry. After thermal treatment at only 800 C, anodic coatings are adherent and homogeneous. Thin films have compact microstructures that confer ceramic protective barrier on metal surface. Further coatings of 10 lm thick are porous and constitute the active anodic material
OH main line masers in the M82 starburst
A study of the distribution of OH gas in the central region of the nearby
active starburst galaxy M82 has confirmed two previously known bright masers
and revealed several new main line masers. Three of these are seen only at 1665
MHz, one is detected only at 1667 MHz, while the rest are detected in both
lines. Observations covering both the 1665 and 1667 MHz lines, conducted with
both the Very Large Array (VLA) and the Multi-Element Radio Linked
Interferometer Network (MERLIN), have been used to accurately measure the
positions and velocities of these features. This has allowed a comparison with
catalogued continuum features in the starburst such as HII regions and
supernova remnants, as well as known water and satellite line OH masers. Most
of the main line masers appear to be associated with known HII regions although
the two detected only at 1665 MHz are seen along the same line of sight as
known supernova remnants.Comment: MNRAS accepted. 16 pages, 13 figure
Discrete Source Survey of 6 GHz OH emission from PNe & pPNe and first 6 GHz images of K 3-35
The aim of this study is to investigate the physical properties of molecular
envelopes of planetary nebulae in their earliest stages of evolution. Using the
100m telescope at Effelsberg, we have undertaken a high sensitivity discrete
source survey for the first excited state of OH maser emission (J=5/2, 2PI3/2
at 6GHz) in the direction of planetary and proto-planetary nebulae exhibiting
18cm OH emission (main and/or satellite lines), and we further validate our
detections using the Nan\c{c}ay radio telescope at 1.6-1.7GHz and MERLIN
interferometer at 1.6-1.7 and 6GHz. Two sources have been detected at 6035MHz
(5cm), both of them are young (or very young) planetary nebulae. The first one
is a confirmation of the detection of a weak 6035MHz line in Vy 2-2. The second
one is a new detection, in K 3-35, which was already known to be an exceptional
late type star because it exhibits 1720MHz OH emission. The detection of
6035MHz OH maser emission is confirmed by subsequent observations made with the
MERLIN interferometer. These lines are very rarely found in evolved stars. The
1612MHz masers surround but are offset from the 1720 and 6035MHz masers which
in turn lie close to a compact 22GHz continuum source embedded in the optical
nebula.Comment: 9 pages, 7 figures, published in A&
Herschel/HIFI deepens the circumstellar NH3 enigma
Circumstellar envelopes (CSEs) of a variety of evolved stars have been found
to contain ammonia (NH3) in amounts that exceed predictions from conventional
chemical models by many orders of magnitude. The observations reported here
were performed in order to better constrain the NH3 abundance in the CSEs of
four, quite diverse, oxygen-rich stars using the NH3 ortho J_K = 1_0 - 0_0
ground-state line. We used the Heterodyne Instrument for the Far Infrared
aboard Herschel to observe the NH3 J_K = 1_0 - 0_0 transition near 572.5 GHz,
simultaneously with the ortho-H2O J_Ka,Kc = 1_1,0 -1_0,1 transition, toward VY
CMa, OH 26.5+0.6, IRC+10420, and IK Tau. We conducted non-LTE radiative
transfer modeling with the goal to derive the NH3 abundance in these objects'
CSEs. For the latter two stars, Very Large Array imaging of NH3
radio-wavelength inversion lines were used to provide further constraints,
particularly on the spatial extent of the NH3-emitting regions. Results. We
find remarkably strong NH3 emission in all of our objects with the NH3 line
intensities rivaling those obtained for the ground state H2O line. The NH3
abundances relative to H2 are very high and range from 2 x 10-7 to 3 x 10-6 for
the objects we have studied. Our observations confirm and even deepen the
circumstellar NH3 enigma. While our radiative transfer modeling does not yield
satisfactory fits to the observed line profiles, it leads to abundance
estimates that confirm the very high values found in earlier studies. New ways
to tackle this mystery will include further Herschel observations of more NH3
lines and imaging with the Expanded Very Large Array.Comment: 4+2 page
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