Gutenberg-Richter’s law in sliding friction of gels

We report on experimental studies of spatio-temporally heterogeneous stick-slip motions in the sliding friction between a hard polymethyl methacrylate (PMMA, plexiglass) block and a soft poly-dimethyl siloxane (PDMS, silicone) gel plate. We perform experiments on two PDMS gels with different viscoelastic properties. For the less viscous gel, large and rapid events are preceded by an alternation of active and less active periods. For the more viscous gel, successive slow slip events take place continuously. The probability distributions of the force drop, a quantity analogous to seismic moment, obey a power law similar to Gutenberg-Richter's empirical law for the frequency-size statistics of earthquakes, and the exponents of the power law vary with the plate velocity and the viscosity of the gel. We propose a simple model to explain the dependence of the power law exponent on the plate velocity, which agrees with experimental results

Stagnation and minimum wage: Optimal minimum wage policy in macroeconomics

This paper argues how an increase in minimum wage affects employment, consumption, and social welfare with dynamic general equilibrium model without market frictions. The study demonstrates that a minimum wage hike reduces an actual unemployment rate and has positive effects on an employment rate under the demand-shortage economy whereas they do not under a non-demand shortage economy. The study also shows that optimal minimum wage which maximize social welfare and minimize an actual unemployment rate when the economy faces the demand-shortage initially. These findings imply that the minimum wage can be considered as one of the effective policy for overcoming deflation and stagnation although it increases the natural rate of unemployment

Stagnation and minimum wage: Optimal minimum wage policy in macroeconomics

This paper argues how an increase in minimum wage affects employment, consumption, and social welfare with dynamic general equilibrium model without market frictions. The study demonstrates that a minimum wage hike reduces an actual unemployment rate and has positive effects on an employment rate under the demand-shortage economy whereas they do not under a non-demand shortage economy. The study also shows that optimal minimum wage which maximize social welfare and minimize an actual unemployment rate when the economy faces the demand-shortage initially. These findings imply that the minimum wage can be considered as one of the effective policy for overcoming deflation and stagnation although it increases the natural rate of unemployment

ASTE Observations of Warm Gas in Low-mass Protostellar Envelopes: Different Kinematics between Submillimeter and Millimeter Lines

With the ASTE telescope, we have made observations of three low-mass protostellar envelopes around L483, B335, and L723 in the submillimeter CS ($J$=7--6) and HCN ($J$=4--3) lines. We detected both the CS and HCN lines toward all the targets, and the typical CS intensity ($\sim$ 1.0 K in T$_{B}$) is twice higher than that of the HCN line. Mapping observations of L483 in these lines have shown that the submillimeter emissions in the low-mass protostellar envelope are resolved, exhibit a western extension from the central protostar, and that the deconvolved size is $\sim$ 5500 AU $\times$ 3700 AU (P.A. = 78$^{\circ}$) in the HCN emission. The extent of the submillimeter emissions in L483 implies the presence of higher-temperature ($\gtrsim$ 40 K) gas at 4000 AU away from the central protostar, which suggests that we need to take 2-dimensional radiative transfer models with a flattened disklike envelope and bipolar cavity into account to explain the temperature structure inside the low-mass protostellar envelope. The position-velocity diagrams of these submillimeter lines in L483 and B335 exhibit different velocity gradients from those found in the previous millimeter observations. In particular, along the axis of the associated molecular outflow the sense of the velocity gradient traced by the submillimeter lines is opposite to that of the millimeter observations or the associated molecular outflow, both in L483 and B335. We suggest that expanding gas motions at the surface of the flattened disklike envelope around the protostar, which is irradiated from the central star directly, are the origin of the observed submillimeter velocity structure.Comment: 20 pages, 11 figure