High-energy, low-jitter, narrowband ps probe laser for kHz-rate fs/ps coherent anti-Stokes Raman scattering.

Hybrid fs/ps coherent anti-Stokes Raman scattering (CARS) thermometry often utilizes ps probe pulses derived from pulse shaping or spectrally filtering the primary laser source or by synchronization with a low repetition rate external laser. This results in limited energy, spectral resolution, and/or repetition rate of the ps probe. In this work, a master-oscillator power-amplifier (MOPA) laser was synchronized to the oscillator of a Ti:sapphire regenerative amplifier to achieve high-energy (600 µJ), narrowband (58 ps) probe pulses at kHz repetition rates. Temporal filtering allows the pulse characteristics to be adjusted for each application. At 25 Torr, relevant to high-speed flows, the kHz-rate MOPA system generated signal-to-noise ratios 3× higher in nitrogen and had improved precision relative to a 10 ps probe derived from spectral filtering and the power-amplifier. The MOPA system also enabled single-shot ro-vibrational hybrid fs/ps CARS thermometry in 650 K heated air.

Spatially multiplexed femtosecond/picosecond coherent anti-Stokes Raman scattering for multipoint array measurements.

A novel, to the best of our knowledge, method for multipoint hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering measurements is presented. The pump/Stokes and probe beams are each split into 16 discrete points with 90 and 24 µJ/pulse, respectively, using simple diffractive optical elements, which are used in combination with a focusing lens and narrowband spectral amplifier for 1 kHz excitation along a linear array of probe volumes. Single-shot and averaged temperature and O2/N2 profile measurements are demonstrated along a line with 1 mm spacing in room temperature and heated N2 flows. This enables measurements over varying spatial extents for 1D profiles and potentially 2D grids in a simple and compact optical arrangement.

Too afraid to Travel? Development of a Pandemic (COVID-19) Anxiety Travel Scale (PATS).

Pandemics are affecting tourism in many ways. Being a niche research field before, the coronavirus (COVID-19) pandemic created a strong urgency to develop this topic. For researching pandemic-induced changes in tourist beliefs and travel behaviour, we developed a construct that measures the intra-personal anxiety of travellers (and non-travellers): the Pandemic (COVID-19) Anxiety Travel Scale (PATS), using two large online studies (N = 2180; N = 2062) and including two different cultural contexts (US and Denmark). In Study 1, explorative and confirmative factors analysis confirms a short and easy-to-use 5-item solution, while the presented model adds face validity. Study 2 confirmed the structure (reliability) and tested nomological validity, by putting PATS into the context of different constructs (xenophobia and prevention focus). Although the proposed scale arose from the coronavirus (COVID-19), it is not limited to this specific pandemic and will hopefully prove to be a valuable measurement tool for future pandemics as well.

Use numbers not words! Communicating hotels' cleaning programs for COVID-19 from the brand perspective.

After hotels in many countries were forced to close in government-imposed lockdowns during the COVID-19 pandemic, there is an inherent need to communicate how they deal with the coronavirus to motivate guests to visit. However, lack of knowledge about how to persuasively communicate about hotels' cleaning programs for COVID-19 can challenge the industry's survival. We investigated how hotels that position their brand as a particular personality (sincere vs. exciting) could benefit from different communication styles (inclusion of numerical vs. verbal quantifiers) when presenting their COVID-19 cleaning procedures. Study 1 explored tourists' central attitudinal responses toward hotels' cleaning programs. Study 2 demonstrated that sincere hotel brands would benefit from using numerical and verbal quantifiers to communicate their cleaning policies, whereas exciting hotel brands would benefit only from numerical quantifiers. Our results invite hotel managers to use their brand personality positioning to influence tourists' attitudes and intentions in a pandemic context.

Dual-output fs/ps burst-mode laser for megahertz-rate rotational coherent anti-Stokes Raman scattering.

A burst-mode laser system is developed for hybrid femtosecond/picosecond (fs/ps) rotational coherent anti-Stokes Raman scattering (RCARS) at megahertz rates. Using a common fs oscillator, the system simultaneously generates time synchronized 1061 nm, 274 fs and 1064 nm, 15.5 ps pulses with peak powers of 350 MW and 2.5 MW, respectively. The system is demonstrated for two-beam fs/ps RCARS in N2 at 1 MHz with a signal-to-noise ratio of 176 at room temperature. This repetition rate is an order of magnitude higher than previous CARS using burst-mode ps laser systems and two to three orders of magnitude faster than previous continuously pulsed fs or fs/ps laser systems.

High-energy laser pulses for extended duration megahertz-rate flow diagnostics.

Optical diagnostics of highly dynamic supersonic and hypersonic flows requires laser sources with a combination of high pulse intensities and fast repetition rates. A burst-mode Nd:YAG laser system is presented for increasing the overall energy of 532 nm pulse trains by ∼100× and the number of high-energy pulses by 30× for extended duration megahertz-rate flow diagnostics. At a lower repetition rate of 100 kHz, unprecedented energies near 1 J/pulse are achieved at 532 nm over a 1.1 ms burst. The laser performance is characterized and demonstrated for megahertz-rate laser-induced breakdown spectroscopy in a Mach 2 turbulent jet.

Shock propagation channels behind the global economic contagion network. The role of economic sectors and the direction of trade.

Examining the spread of macroeconomic phenomena between countries has become increasingly popular after the 2008 economic crisis, but the recent COVID-19 pandemic rendered this issue much more relevant as it shed more light on the risks arising from strongly interconnected economies. This paper intends to extend previous studies in this line by examining the relationship between trade openness and business cycle synchronization. It extends the scope of previous analyses in three areas. First, we use a Granger-causality approach to identify synchronization. Second, trade is broken down to the sector level and third, we distinguish between upstream and downstream connections. These developments allow for a directed approach in the analysis. We use conditional logit regressions to estimate the effect of trade openness on the probability of shock-transmission. The results presented in this study contribute to the literature in two ways. First, in addition to revealing a positive effect of aggregate two-way trade on shock-contagion, it also points out that this overall effect hides diverse behavior in specific trading sectors as well as upstream and downstream channels. Second, while some sectors are not significant channels of shock-transmission in either directions, upstream channels seem to be important in agriculture while downstream channels dominate machinery and other manufactures. Also, there are sectors (chemicals and related products) trade in which affects shock-transmission negatively.

The strength of domestic production networks: an economic application of the Finn cycling index.

There has been an increasing interest in analyzing the structure of domestic and global supply chains/networks in the past decade. Concerns about potential (systemic) risks resulting from overdependence on global supply networks have been magnified during the lockdowns triggered by the COVID-19 pandemic in the last year. Strengthening local and/or domestic networks may be an adequate approach to overcome the severe economic implications of this overdependence, but it also rises the question of how one can measure the strength of domestic supply/production networks and design an appropriate structure. The objective of this paper is to propose a method for measurement and to provide a first-cut analysis with this method on a sample of economies. Building on ecological network analysis, we borrow the Finn cycling index from its toolbox and show a ranking of countries with respect to the strength of their domestic production networks based on this index. The results suggest that the countries are very heterogeneous both in terms of the level of cycling index and its sectoral decomposition. Using panel-econometric techniques, we point out the role of the openness and structural asymmetry in shaping this strength, also controlling for other macroeconomic characteristics of the economies. The estimates reveal that openness has a negative, while asymmetry has a positive effect on this index, but other country-specific characteristics also play a role in shaping the systemic operation of national economies as measured by the Finn cycling index.