3,960 research outputs found
Investment-Specific Technology Shocks in a Small Open Economy
In this paper we examine the behavioral responses of key macroeconomic variables in Canada to exogenous innovations to investment specific technology. This is done by developing a stylized international real business cycle model which is simulated to explore its ability to shed new light on the dynamic behavior of the standard small open economy. The results indicate that this model can quantitatively replicate the key dynamic features of the post-war Canadian economy, and thus shocks to investment-specific technology can be considered an important propagation mechanism for studying and understanding modern macroeconomic dynamics in small open economies. Moreover, when the model was augmented with an endogenous utilization rate it was able to generate the counter-cyclical behavior of the external accounts - without appealing to an adjustment cost parameter and/or a propagation mechanism whose volatility and persistence are artificially low.Endogenous rate of time preference; Investment-specific shocks; Relative price of investment goods
Investment-Specific Technology Shocks in a Small Open Economy
This paper re-examines the behavioral responses of key macroeconomic variables in Canada to exogenous shocks to the relative price of investment goods. It does so by developing a stylized two-sector real business cycle model which is simulated to explore its ability to shed new light on the dynamic behavior of the standard small open economy. The results indicate that this model can qualitatively and quantitatively replicate the dynamic features of the Canadian economy, and thus shocks to investment-specific technology can be considered an important propagation mechanism for studying and understanding modern macroeconomic dynamics in small open economies.Endogenous rate of time preference, International real business cycle, Investment-specific shocks, Relative price of investment goods, Small open economy
Acidosis Is a Key Regulator of Osteoblast Ecto-Nucleotidase Pyrophosphatase/Phosphodiesterase 1 (NPP1) Expression and Activity
Previous work has shown that acidosis prevents bone nodule formation by osteoblasts in vitro by inhibiting mineralisation of the collagenous matrix. The ratio of phosphate (Pi) to pyrophosphate (PPi) in the bone microenvironment is a fundamental regulator of bone mineralisation. Both Pi and PPi, a potent inhibitor of mineralisation, are generated from extracellular nucleotides by the actions of ecto‐nucleotidases. This study investigated the expression and activity of ecto‐nucleotidases by osteoblasts under normal and acid conditions. We found that osteoblasts express mRNA for a number of ecto‐nucleotidases including NTPdase 1–6 (ecto‐nucleoside triphosphate diphosphohydrolase) and NPP1‐3 (ecto‐nucleotide pyrophosphatase/phosphodiesterase). The rank order of mRNA expression in differentiating rat osteoblasts (day 7) was Enpp1 > NTPdase 4 > NTPdase 6 > NTPdase 5 > alkaline phosphatase > ecto‐5‐nucleotidase > Enpp3 > NTPdase 1 > NTPdase 3 > Enpp2 > NTPdase 2. Acidosis (pH 6.9) upregulated NPP1 mRNA (2.8‐fold) and protein expression at all stages of osteoblast differentiation compared to physiological pH (pH 7.4); expression of other ecto‐nucleotidases was unaffected. Furthermore, total NPP activity was increased up to 53% in osteoblasts cultured in acid conditions (P < 0.001). Release of ATP, one of the key substrates for NPP1, from osteoblasts, was unaffected by acidosis. Further studies showed that mineralised bone formation by osteoblasts cultured from NPP1 knockout mice was increased compared with wildtypes (2.5‐fold, P < 0.001) and was partially resistant to the inhibitory effect of acidosis. These results indicate that increased NPP1 expression and activity might contribute to the decreased mineralisation observed when osteoblasts are exposed to acid conditions
Non-linear response of single-molecule magnets: field-tuned quantum-to-classical crossovers
Quantum nanomagnets can show a field dependence of the relaxation time very
different from their classical counterparts, due to resonant tunneling via
excited states (near the anisotropy barrier top). The relaxation time then
shows minima at the resonant fields H_{n}=n D at which the levels at both sides
of the barrier become degenerate (D is the anisotropy constant). We showed that
in Mn12, near zero field, this yields a contribution to the nonlinear
susceptibility that makes it qualitatively different from the classical curves
[Phys. Rev. B 72, 224433 (2005)]. Here we extend the experimental study to
finite dc fields showing how the bias can trigger the system to display those
quantum nonlinear responses, near the resonant fields, while recovering an
classical-like behaviour for fields between them. The analysis of the
experiments is done with heuristic expressions derived from simple balance
equations and calculations with a Pauli-type quantum master equation.Comment: 4 pages, 3 figures. Submitted to Phys. Rev. B, brief report
First L-band Interferometric Observations of a Young Stellar Object: Probing the Circumstellar Environment of MWC 419
We present spatially-resolved K- and L-band spectra (at spectral resolution R
= 230 and R = 60, respectively) of MWC 419, a Herbig Ae/Be star. The data were
obtained simultaneously with a new configuration of the 85-m baseline Keck
Interferometer. Our observations are sensitive to the radial distribution of
temperature in the inner region of the disk of MWC 419. We fit the visibility
data with both simple geometric and more physical disk models. The geometric
models (uniform disk and Gaussian) show that the apparent size increases
linearly with wavelength in the 2-4 microns wavelength region, suggesting that
the disk is extended with a temperature gradient. A model having a power-law
temperature gradient with radius simultaneously fits our interferometric
measurements and the spectral energy distribution data from the literature. The
slope of the power-law is close to that expected from an optically thick disk.
Our spectrally dispersed interferometric measurements include the Br gamma
emission line. The measured disk size at and around Br gamma suggests that
emitting hydrogen gas is located inside (or within the inner regions) of the
dust disk.Comment: Accepted for publication in Ap
The Pathology of Metal Culverts
Metal culverts are robust structures, but the very large number built every year entails, statistically, a rather high level of pathology. The various aspects of this pathology are analyzed below, first from a general point of view and then through an examination of three particularly instructive cases
Pressure Driven Flow of Polymer Solutions in Nanoscale Slit Pores
Polymer solutions subject to pressure driven flow and in nanoscale slit pores
are systematically investigated using the dissipative particle dynamics
approach. We investigated the effect of molecular weight, polymer concentration
and flow rate on the profiles across the channel of the fluid and polymer
velocities, polymers density, and the three components of the polymers radius
of gyration. We found that the mean streaming fluid velocity decreases as the
polymer molecular weight or/and polymer concentration is increased, and that
the deviation of the velocity profile from the parabolic profile is accentuated
with increase in polymer molecular weight or concentration. We also found that
the distribution of polymers conformation is highly anisotropic and non-uniform
across the channel. The polymer density profile is also found to be
non-uniform, exhibiting a local minimum in the center-plane followed by two
symmetric peaks. We found a migration of the polymer chains either from or
towards the walls. For relatively long chains, as compared to the thickness of
the slit, a migration towards the walls is observed. However, for relatively
short chains, a migration away from the walls is observed.Comment: 11 pages, 13 figure
Stronger Misdirection in Curved than in Straight Motion
Illusions developed by magicians are a rich and largely untapped source of insight into perception and cognition. Here we show that curved motion, as employed by the magician in a classic sleight of hand trick, generates stronger misdirection than rectilinear motion, and that this difference can be explained by the differential engagement of the smooth pursuit and the saccadic oculomotor systems. This research exemplifies how the magician’s intuitive understanding of the spectator’s mindset can surpass that of the cognitive scientist in specific instances, and that observation-based behavioral insights developed by magicians are worthy of quantitative investigation in the neuroscience laboratory
Strong Near-Infrared Emission Interior to the Dust-Sublimation Radius of Young Stellar Objects MWC275 and AB Aur
Using the longest optical-interferometeric baselines currently available, we
have detected strong near-infrared (NIR) emission from inside the
dust-destruction radius of Herbig Ae stars MWC275 and AB Aur. Our
sub-milli-arcsecond resolution observations unambiguously place the emission
between the dust-destruction radius and the magnetospheric co-rotation radius.
We argue that this new component corresponds to hot gas inside the
dust-sublimation radius, confirming recent claims based on spectrally-resolved
interferometry and dust evaporation front modeling.Comment: 12 pages, 4 figures, Accepted for publication in ApJ
The effect of prolonged simulated non- gravitational environment on mineral balance in the adult male, volume 1 Final report
Effect of prolonged bed rest with simulated weightlessness on mineral balance in male adult - Vol.
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