10 research outputs found
Solving Numerically and Visualizing an IS-MP Model with Financial Intermediation
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Simulating and Visualizing the Performance of Leveraged Investing
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Essays on Monetary Policy at the Effective Lower Bound and with Financial Disruption
No full textThis dissertation consists of three self-contained chapters.The first chapter analyzes the effectiveness of optimal sustainable forward guidance at the effective lower bound when the economy faces occasional financial disruptions. Financial disruptions make households and firms respond less to future monetary shocks because of precautionary saving and the value of current profit increases. As a result, the following three results emerge. First, forward guidance affects the current economy much less strongly without changing its effect when the economy exits the lower bound. Second, the effectiveness of forward guidance becomes weaker even if the central bank has perfect credibility and commit to stronger forward guidance. Third, since output gaps and inflation experience a larger deviation from the optimal level at exit periods, credibility concerns make the effectiveness of optimal sustainable forward guidance even weaker.The second chapter analyzes the effectiveness of forward guidance in a low natural rate of interest environment. Since the strength of forward guidance depends on how lower and how many more periods the central bank will set the real interest below the natural rate, a low natural rate environment makes the central bank commit to forward guidance with longer horizons to achieve the same effects on the current period. This increases the cost of forward guidance at the exit periods because the deviation from the optimal level becomes larger and lasts longer. As a result, the effectiveness of forward guidance becomes weaker even if the central bank has perfect credibility. Moreover, gaining credibility becomes harder and this even weakens the effectiveness of forward guidance. The third chapter analyzes how the effects of monetary policy depend on the condition of the financial sector. With heterogeneous households in terms of the marginal cost of working, there exist essential financial needs. When it is more costly for the financial sector to extend lending than normal times, the effects of monetary policy becomes smaller. The larger the households heterogeneity is, the smaller the effects become. This is in sharp contrast with the case when there are no financial frictions in that the households heterogeneity does not affect the effects of monetary policy with the perfect financial market. The results also hold for forward guidance
A Comparison of Buy-and-Hold and Threshold Strategies for Leveraged Investments
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Near-IR investigation of the thermal structure of the deep atmosphere of Venus
No full textDespite a large number of in-situ missions, only VeGa-2 provided the high-resolution thermal measurements of the deep atmosphere of Venus below 12 km and they indicated a highly unstable layer below 7 km altitude. Lebonnois and Schubert (2017) tried to explain the VeGa-2 measurements by introducing a theory of a composition gradient in the deep atmosphere of Venus. In our research, we test this theory of composition gradient by making use of the near-infrared observations from Akatsuki and Venus Express missions in combination with the altimetry observations from Magellan Mission. To make use of the highly contaminated Akatsuki dataset, we develop a procedure to sequentially reduce the contamination to an acceptable level. Next, an atmospheric radiative transfer model is built to simulate the thermal emission coming from the surface of Venus, which is then used to generate a temperature vs altitude profile from the observations. Using this temperature profile we investigate the theory of composition gradient.Aerospace Engineerin
Subsurface infrastructure visualization: Two implementation scenarios for a handheld mobile device
No full textThis thesis discusses the utilization of handheld displays in software service solutions for subsurface infrastructure visualization in urban environments. The thesis discusses the challenges of using augmented reality (AR) for visualizing the infrastructure below the surface of the ground using a mobile device for mapping and rendering.
The thesis reviews the current state-of-the-art tracking technologies with regard to mobile devices: AR tracking, interaction, and display technologies. The author identifies the benefits and limitations of these technologies for the requirements of this thesis.
Two implementations are devised. The first, MIT's CityScope digitalized sandbox-based city planning scenario forms the simulated solution. The second, the real-world Trimble implementation scenario, maps the underground cabling beneath the Otaniemi campus area of Aalto University, Finland. Both scenarios are implemented by the author with fully functional mobile service solutions. These solutions are analyzed, the results discussed and some conclusions are drawn.
In summary, the value proposition of AR technology was successfully validated in both implementations. However, there remain crucial issues related to performance and usability that need to be first overcome before AR technology is ready for widespread adoption by industry. Overcoming these limitations should form the topic of further study, with the main focus being on improving system performance in order to mitigate the computational burden on the mobile handsets
How waves and turbulence maintain the super-rotation of Venus' atmosphere
No full textVenus has a thick atmosphere that rotates 60 times as fast as the surface, a phenomenon known as superrotation. We use data obtained from the orbiting Akatsuki spacecraft to investigate how the super-rotation is maintained in the cloud layer, where the rotation speed is highest. A thermally induced latitudinal-vertical circulation acts to homogenize the distribution of the angular momentum around the rotational axis. Maintaining the super-rotation requires this to be counteracted by atmospheric waves and turbulence. Among those effects, thermal tides transport the angular momentum, which maintains the rotation peak, near the cloud top at low latitudes. Other planetary-scale waves and large-scale turbulence act in the opposite direction. We suggest that hydrodynamic instabilities adjust the angular-momentum distribution at mid-latitudes
Polarimetry as a Tool for Observing Orographic Gravity Waves on Venus
No full textInternational audiencePlanet-wide stationary gravity waves have been observed with the thermal camera on the Akatsuki spacecraft. These waves have been attributed to the underlying surface topography and have successfully been reproduced using the Institut Pierre Simon Laplace (IPSL) Venus Mesoscale Model (VMM). Here, we use numerical radiative transfer computations of the total and polarized fluxes of the sunlight that is reflected by Venus under the conditions of these gravity waves to show that the waves could also be observed in polarimetric observations. To model the waves, we use the density perturbations computed by the IPSL VMM. We show the computed wave signatures in the polarization for nadir-viewing geometries observed by a spacecraft in orbit around Venus and as they could be observed using an Earth-based telescope. We find that the strength of the signatures of the atmospheric density waves in the degree of polarization of the reflected sunlight depends not only on the density variations themselves, but also on the wavelength and the cloud top altitude. Observations of such wave signatures on the dayside of the planet would give insight into the occurrence of the waves and possibly into the conditions that govern their onset and development. The computed change in degree of polarization due to these atmospheric density waves is about 1000 ppm at a wavelength of 300 nm. This signal is large enough for an accurate polarimeter to detect
A Genetically Encoded Probe for Live-Cell Imaging of H4K20 Monomethylation
No full textAbstractEukaryotic gene expression is regulated in the context of chromatin. Dynamic changes in post-translational histone modification are thought to play key roles in fundamental cellular functions such as regulation of the cell cycle, development, and differentiation. To elucidate the relationship between histone modifications and cellular functions, it is important to monitor the dynamics of modifications in single living cells. A genetically encoded probe called mintbody (modification-specific intracellular antibody), which is a single-chain variable fragment tagged with a fluorescent protein, has been proposed as a useful visualization tool. However, the efficacy of intracellular expression of antibody fragments has been limited, in part due to different environmental conditions in the cytoplasm compared to the endoplasmic reticulum where secreted proteins such as antibodies are folded. In this study, we have developed a new mintbody specific for histone H4 Lys20 monomethylation (H4K20me1). The specificity of the H4K20me1-mintbody in living cells was verified using yeast mutants and mammalian cells in which this target modification was diminished. Expression of the H4K20me1-mintbody allowed us to monitor the oscillation of H4K20me1 levels during the cell cycle. Moreover, dosage-compensated X chromosomes were visualized using the H4K20me1-mintbody in mouse and nematode cells. Using X-ray crystallography and mutational analyses, we identified critical amino acids that contributed to stabilization and/or proper folding of the mintbody. Taken together, these data provide important implications for future studies aimed at developing functional intracellular antibodies. Specifically, the H4K20me1-mintbody provides a powerful tool to track this particular histone modification in living cells and organisms
