Non-Perturbative Renormalization Group Flows in Two-Dimensional Quantum Gravity

Recently a block spin renormalization group approach was proposed for the dynamical triangulation formulation of two-dimensional quantum gravity. We use this approach to examine non-perturbatively a particular class of higher derivative actions for pure gravity.Comment: 17 page

Reshaping Metro Manila: Gentrification, Displacement, and the Challenge Facing the Urban Capital

Globalization and liberal economic reforms provide both opportunities and threats for developing cities. It can bring much needed capital and economic development but also at the possible cost of displacement and marginalization. Metro Manila contributes US$7.7 billion to the Philippine economy by remaining competitive in attracting and facilitating the flow of capital. However, this economic development translates to displacement, with its very citizens being affected. We analyze this phenomenon through the existing literature on Metro Manila and gentrification. This paper addresses the key questions: Who are the key players in Metro Manila’s gentrification? What are the implications of their actions? In this analysis, we use Neil Smith’s gentrification framework. We find that the key players involved in this development have prioritized competitiveness by facilitating capital in a globalized world at the cost of ignoring Metro Manila’s marginalized households. To continually ensure capital, the private sector has captured Metro Manila with the urban elites benefiting the most.Metro Manila has been successful in attracting capital and economic progress, but exclusively for consumers who can afford it. While this paper is primarily descriptive in nature, we hope to pose this as a challenge for government to pursue stronger inclusive policies in the urban capital.

A High-Order Low-Order Algorithm with Exponentially-Convergent Monte Carlo for Thermal Radiative Transfer Problems

We have implemented a new high-order low-order (HOLO) algorithm for solving thermal radiative transfer (TRT) problems. Within each discrete time step, fixed-point iterations are performed between a high-order (HO) exponentially-convergent Monte Carlo (ECMC) solver and a low-order (LO) system of equations. The LO system is based on spatial and angular moments of the transport equation and a linear-discontinuous finite-element (LDFE) spatial representation, producing equations similar to the standard S2 equations. The LO solver is fully implicit in time and efficiently converges the non-linear temperature dependence with Newton's method. The HO solver provides a globally accurate solution for the angular intensity to a fixed-source, pure absorber transport problem. This global solution is used to compute consistency terms in the LO equations that require the HO and LO solutions to converge towards the same solution. The use of ECMC allows for the efficient reduction of statistical noise in the solution. We investigated several extensions of this algorithm. A parametric closure of the LO system was used for the spatial variable, based on local relations computed with the HO solver. The spatial closure improves consistency between the two solvers compared to a standard LDFE spatial discretization of the LO system. The ECMC algorithm has been extended to integrate the angular intensity in time, with a consistent time closure of the LO radiation equations. The time closure increases accuracy in optically-thin problems compared to a backward Euler discretization. Finally, we have applied standard source iteration and Krylov procedures to iteratively solve the LO equations, with linear diffusion synthetic acceleration. Herein, we present results for one-dimensional, gray test problems. Results demonstrate several desirable properties of this algorithm: the HOLO method preserves the equilibrium diffusion limit, prevents violation of the maximum principle, and can provide high-fidelity MC solutions to the TRT equations with minimal statistical noise. We have compared results with an implicit Monte Carlo (IMC) code and compared the efficiency of ECMC to standard Monte Carlo in this HOLO algorithm. Our HOLO algorithm is more accurate and more efficient than standard IMC. The extent to which this is so is problem-dependent

Repellency Assessment of Nepeta cataria Essential Oils and Isolated Nepetalactones on Aedes aegypti.

There is an increased need for improved and affordable insect repellents to reduce transmission of rapidly spreading diseases with high mortality rates. Natural products are often used when DEET cannot be afforded or accessed and when consumers choose not to use a synthetic repellent. The essential oils from two newly bred Nepeta cataria (catnip) plants representing two different chemotypes and their respective isolated nepetalactone isomers were evaluated as mosquito repellents against Aedes aegypti mosquitoes that transmit the Zika and Dengue virus in a one choice landing rate inhibition assay. A dose response curve was generated for each treatment and a time course analysis of repellency was performed over 24 hours with a N. cataria essential oil sample. The results indicate that all essential oil samples and their respective purified nepetalactone isomers were able to achieve greater than 95% repellency. Between two and four hours, the ability to repel more than 95% of the mosquitoes diminished. At the lowest concentrations tested, the nepetalactones and crude essential oil samples were more effective than DEET at reducing the number of mosquito landings

Real estate prices and corporate investment: theory and evidence of heterogeneous effects across firms

In this paper, we investigate the effect of real estate prices on productive investment. We build a simple theoretical framework of firms’ investment with credit rationing and real estate collateral. We show that real estate prices affect firms’ borrowing capacities through two channels. An increase in real estate prices raises the value of the firms’ pledgeable assets and mitigates the agency problem characterizing the creditor-entrepreneur relationship. It simultaneously cuts the expected profit due to the increase in the cost of inputs. While the literature only focuses on the first channel, the identification of the second channel allows for heterogeneous effects of real estate prices on investment across firms. We test our theoretical predictions using a large French database. We do find heterogeneous effects of real estate prices on productive investment depending on the position of the firms in the sectoral distributions of real estate holdings. Our preferred estimates indicate that a 10% increase in real estate prices causes a 1% decrease in the investment rate of firms in the first decile of the distribution but a 6% increase in the investment rate of firms belonging to the last decile

Three-Dimensional Quantum Gravity Coupled to Gauge Fields

We show how to simulate U(1) gauge fields coupled to three-dimensional quantum gravity and then examine the phase diagram of this system. Quenched mean field theory suggests that a transition separates confined and deconfined phases (for the gauge matter) in both the negative curvature phase and the positive curvature phase of the quantum gravity, but numerical simulations find no evidence for such transitions.Comment: 16 page

Phase diagram of three-dimensional dynamical triangulations with a boundary

We use Monte Carlo simulation to study the phase diagram of three-dimensional dynamical triangulations with a boundary. Three phases are indentified and characterized. One of these phases is a new, boundary dominated phase; a simple argument is presented to explain its existence. First-order transitions are shown to occur along the critical lines separating phases.Comment: 9 pages, 5 EPS figures. v2 corrects typos in table

Three Dimensional Quantum Gravity Coupled to Ising Matter

We establish the phase diagram of three--dimensional quantum gravity coupled to Ising matter. We find that in the negative curvature phase of the quantum gravity there is no disordered phase for ferromagnetic Ising matter because the coordination number of the sites diverges. In the positive curvature phase of the quantum gravity there is evidence for two spin phases with a first order transition between them.Comment: 12 page