World population in 2050: assessing the projections: discussion

I would like to follow up on the last sentence of the excellent presentation by Joel Cohen. It is indeed true that the lag between new methodological developments and their actual implementation by statistical agencies is regrettably long, but I think there is some hope that the speed of applying innovations has been accelerating over this century. This is the case in many other areas, and it would be surprising if it were not the case in the field of population forecasting. I would assess with a probability of well above 90 percent that by the end of this century, institutional procedures for projecting population will include probabilistic elements. ; In the following, I would like to mention three additional aspects [new methods, extreme events, and projections of population by level of education] complementing the important remarks made by Cohen.Demography ; Economic conditions

Higgs self coupling measurement in e+e- collisions at center-of-mass energy of 500 GeV

Feasibility of the measurement of the trilinear self-couplings of the Higgs boson is studied. Such a measurement would experimentally determine the structure of the Higgs potential. Full hadronic and semi-leptonic final states of the double-Higgs strahlung have been investigated.Comment: 10 pages, 5 tables, 8 figure

Dissipative Quantum Dynamics and Optimal Control using Iterative Time Ordering: An Application to Superconducting Qubits

We combine a quantum dynamical propagator that explicitly accounts for quantum mechanical time ordering with optimal control theory. After analyzing its performance with a simple model, we apply it to a superconducting circuit under so-called Pythagorean control. Breakdown of the rotating-wave approximation is the main source of the very strong time-dependence in this example. While the propagator that accounts for the time ordering in an iterative fashion proves its numerical efficiency for the dynamics of the superconducting circuit, its performance when combined with optimal control turns out to be rather sensitive to the strength of the time-dependence. We discuss the kind of quantum gate operations that the superconducting circuit can implement including their performance bounds in terms of fidelity and speed.Comment: 16 pages, 11 figure

Why Is It So Difficult to Beat the Random Walk Forecast of Exchange Rates?

We propose a stylized exchange rate model based on diversity and weight of opinion. Our model departs from standard assumptions in that we allow for heterogeneous agents. We show that such a model can explain both the observed volatility and the persistence of real and nominal exchange rate movements and thus in some measure resolves Rogoff’s (1996) purchasing power parity puzzle. Our empirical analysis reconciles the well-known difficulties in beating the random walk forecast model with the statistical evidence of nonlinear mean reversion in deviations from fundamentals. We find strong evidence of long-horizon predictability both in theory and in practice. We also explain why it is difficult to exploit this predictability in out-ofsample forecasts. Our results not only lend support to economists’ beliefs that the exchange rate is inherently predictable, but they also help us to understand the reluctance of applied forecasters to abandon chartists methods in favor of models based on economic fundamentals.Purchasing power parity, Real exchange rate, Random walk, Economic models of exchange rate determination, Long-horizon regression tests.

Nonequilibrium work distribution of a quantum harmonic oscillator

We analytically calculate the work distribution of a quantum harmonic oscillator with arbitrary time-dependent angular frequency. We provide detailed expressions for the work probability density for adiabatic and nonadiabatic processes, in the limit of low and high temperature. We further verify the validity of the quantum Jarzynski equalityComment: 6 pages, 3 figure