How Good Are Embodied And Disembodied Idea Flows In Bridging Income Gaps And Idea Gaps?

This paper empirically evaluates the relative importance of embodied versus disembodied idea flows in explaining income gaps and idea gaps. Trade is used as a measure of embodied idea flows and telephone call traffic a measure of disembodied flows. Since both trade and telephone traffic may be endogenous, this paper uses the geographic, linguistic, and colonial components of trade and telephone traffic as instruments to identify their effects on income and total factor productivity (TFP). The results provide little support for the embodied object models when both trade and telephone traffic are included in the regressions. Telephone traffic has a quantitatively much large effect on income per worker and TFP than trade.

The Manufacturing Sector Did Contribute to Convergence Among the OECD Countries

This paper revisits the role of sectors in aggregate convergence. The existing evidence is inconclusive because its methodology depends sensitively on the conversion factor used to compare sectoral productivity levels across countries. This paper proposes a robust methodology -- ß-decomposition - to directly estimate how much the productivity growth in each sector and between -sector restructuring contribute to convergence. This methodology avoids the sectoral PPP-conversion-factor problem because it compares only sectoral growth rates and shares -- not levels -- across countries. The evidence suggests that productivity growth in both manufacturing and services were important in driving aggregate productivity convergence among the OECD countries. The results are robust to the choice of base year.Convergence, ß-Decomposition, Shift-Share Decomposition, Sectoral Decomposition

Some International Evidence on Deviations from Pocketbook Voting and Its Relevance for the Political Economy

This paper empirically investigates whether individuals indeed vote with their pocketbooks. Individual level data from the General Social Survey and the World Values Survey show significant deviations from pocketbook voting even among the poorest and the richest individuals in the sample. Differences in income status, education status, and perceived social mobility explain only a small fraction of the cross-country variation in the preference for income equality. Economically large and statistically significant country effects remain. There is no evidence that the median preference for income equality is more intense when incomes are more unequal or when the regimes are more democratic, a finding that rules out redistributive pressure as an important mechanism through which inequality affects growth under majority rule.

The Channels of Economic Growth: A Channel Decomposition Exercise

This paper formally introduces channel decomposition, a method that systematically decomposes the channels through which the determinants of growth operate, into the analysis of economic growth. Under channel decomposition, the determinants could affect economic growth through physical capital accumulation, through human capital acquisition, and/or through growth in total factor productivity. Thus, by examining the outcomes of the decomposition, we can test alternative models, as different models often imply different channels of operation for the determinants. Methodologically, channel decomposition combines growth accounting with regression analysis, rather than regarding them as alternative approaches. With this method, it becomes clear that technological catch-up, not factor accumulation, accounts for the widely documented phenomenon of conditional convergence. This finding turns out to be extremely robust. In effect, this finding puts the final nails in the coffin of the Neoclassical growth model, as the model can neither explain cross-country growth, nor can it explain conditional convergence. The method also shows that both rich and poor countries converge mainly through technological catch-up, although richer countries converge much faster than the poor.

Waveform Design of DFRC System for Target Detection in Clutter Environment

Dual-function radar and communication (DFRC) has recently drawn significant attention due to its enormous potential. This letter deals with waveform design of DFRC to improve target detectability embedded in clutter environment while guaranteeing the service quality of communication users. Our design objective is to maximize the output signal-to-clutter-plus-noise ratio (SCNR) of multiple-input multiple-output (MIMO) radar, subject to worst-case received symbol errors at communication users. Coordinate descent (CD) as an efficient iteration algorithm is proposed to solve above optimization problem, which splits high-dimensional problem into multiple one-dimensional problem. Furthermore, we introduce Dinkelbach algorithm (DA) to increase rate of convergence, which is an efficient way to reduce complexity. Finally, simulation results are presented to illustrate the effectiveness of the proposed techniques

Robust Preparation of Many-body Ground States in Jaynes-Cummings Lattices

Strongly-correlated polaritons in Jaynes-Cummings (JC) lattices can exhibit quantum phase transitions between the Mott-insulating and superfluid phases at integer fillings. The prerequisite to observe such phase transitions is to pump polariton excitations into a JC lattice and prepare them into appropriate ground states. Despite previous efforts, it is still challenging to generate many-body states with high accuracy. Here we present an approach for the robust preparation of many-body ground states of polaritons in finite-sized JC lattices by optimized nonlinear ramping. We apply a Landau-Zener type of estimation to this finite-sized system and derive the optimal ramping index for selected ramping trajectories, which can greatly improve the fidelity of the prepared states. With numerical simulation, we show that by choosing an appropriate ramping trajectory, the fidelity in this approach can remain close to unity in almost the entire parameter space. This approach can shed light on high-fidelity state preparation in quantum simulators and advance the implementation of quantum simulation with practical devices.Comment: 9 pages, 7 figure

Pulse-spacing manipulation in a passively mode-locked multipulse fiber laser

Passively mode-locked fiber lasers have been intensively applied in various research fields. However, the passive mode-locking typically operates in free-running regime, which easily produces messy multiple pulses due to the fruitful nonlinear effects involved in optical fibers. Actively controlling those disordered pulses in a passively mode-locked laser is of great interest but rarely studied. In this work, we experimentally investigate a flexible pulse-spacing manipulation in the passively mode-locked multipulse fiber laser by both intracavity and extracavity methods. A tuning range of pulse spacing up to 1.5 ns is achieved. More importantly, continuous pulse-spacing modulation is successfully demonstrated through external optical injection. It is anticipated that the results can contribute to the understanding of laser nonlinear dynamics and pursuing the optimal performance of passively mode-locked fiber lasers for practical applications

Tri-band spectroscopic optical coherence tomography based on optical parametric amplification for lipid and vessel visualization

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Video-rate centimeter-range optical coherence tomography based on dual optical frequency combs by electro-optic modulators

Imaging speed and range are two important parameters for optical coherence tomography (OCT). A conventional video-rate centimeter-range OCT requires an optical source with hundreds of kHz repetition rate and needs the support of broadband detectors and electronics (>1 GHz). In this paper, a type of video-rate centimeter-range OCT system is proposed and demonstrated based on dual optical frequency combs by leveraging electro-optic modulators. The repetition rate difference between dual combs, i.e. the A-scan rate of dual-comb OCT, can be adjusted within 0~6 MHz. By down-converting the interference signal from optical domain to radio-frequency domain through dual comb beating, the down-converted bandwidth of the interference signal is less than 22.5 MHz which is at least two orders of magnitude lower than that in conventional OCT systems. A LabVIEW program is developed for video-rate operation, and the centimeter imaging depth is proved by using 10 pieces of 1-mm thick glass stacked as the sample. The effective beating bandwidth between two optical comb sources is 7 nm corresponding to ~108 comb lines, and the axial resolution of the dual-comb OCT is 158 µm. Dual optical frequency combs provide a promising solution to relax the detection bandwidth requirement in fast long-range OCT systems