The size effect is alive well but visible only when the economy is in high volatility regimes. This paper develops variant conditional asset pricing tests for the size effect with independent ...business cycle and volatility regimes and shows that the size effect is present conditionally during the high‐volatility regimes. This result is robust across two countries (United States and United Kingdom) with various specifications and the January effect. An economic rationale for the relation between the size premium and macrovolatility risk is provided through the capital‐market‐imperfection hypothesis.
Quantum beats, periodic oscillations arising from coherent superposition states, have enabled exploration of novel coherent phenomena. Originating from strong Coulomb interactions and reduced ...dielectric screening, two-dimensional transition metal dichalcogenides exhibit strongly bound excitons either in a single structure or hetero-counterpart; however, quantum coherence between excitons is barely known to date. Here we observe exciton quantum beats in atomically thin ReS2 and further modulate the intensity of the quantum beats signal. Surprisingly, linearly polarized excitons behave like a coherently coupled three-level system exhibiting quantum beats, even though they exhibit anisotropic exciton orientations and optical selection rules. Theoretical studies are also provided to clarify that the observed quantum beats originate from pure quantum coherence, not from classical interference. Furthermore, we modulate on/off quantum beats only by laser polarization. This work provides an ideal laboratory toward polarization-controlled exciton quantum beats in two-dimensional materials.
Healthcare-associated infections (HAIs) are a major problem in hospital infection control. Although HAIs can be suppressed using contact precautions, such precautions are expensive, and we can only ...apply them to a small fraction of patients (i.e., a limited budget). In this work, we focus on two clinical problems arising from the limited budget: (a) choosing the best patients to be placed under precaution given a limited budget to minimize the spread (the isolation problem), and (b) choosing the best patients to release when limited budget requires some of the patients to be cleared from precaution (the clearance problem). A critical challenge in addressing them is that HAIs have multiple transmission pathways such that locations can also accumulate 'load' and spread the disease. One of the most common practices when placing patients under contact precautions is the regular clearance of pathogen loads. However, standard propagation models like independent cascade (IC)/susceptible-infectious-susceptible (SIS) cannot capture such mechanisms directly. Hence to account for this challenge, using non-linear system theory, we develop a novel spectral characterization of a recently proposed pathogen load based model, 2-MODE-SIS model, on people/location networks to capture spread dynamics of HAIs. We formulate the two clinical problems using this spectral characterization and develop effective and efficient algorithms for them. Our experiments show that our methods outperform several natural structural and clinical approaches on real-world hospital testbeds and pick meaningful solutions.
Triboelectric nanogenerators (TENGs) are actively being researched and developed to become a new external power unit for various electronics and applications. Wind is proposed as a mechanical energy ...source to flutter the dielectric film in wind-driven TENGs as it is clean, abundant, ubiquitous, and sustainable. Herein, we propose a TENG structure with dielectric films bent in four directions to collect the wind energy supply from all directions, unlike the conventional wind-driven TENGs which can only harvest the wind energy from one direction. Aluminum (Al) layer was intercalated within the dielectric film to improve electrostatic induction, resulting in improved triboelectric performances. Maximum open-circuit voltage (V
oc
) of 233 V, short-circuit current (I
sc
) of 348 µA, and output power density of 46.1 W m
− 2
at an external load of 1 MΩ under a wind speed of 9 m s
− 1
were revealed, and it faithfully lit “LED” characters composed of 25 LEDs.
To enhance the performance of semiconducting metal oxides, as hydrogen (H 2 ) sensor, we introduced a high carrier concentration (N d ) metal oxide, indium- gallium-zinc oxide (IGZO), combined with ...palladium (Pd) catalysis. This allowed the detection of low concentrations of H 2 at room temperature. The base current level was linearly increased with the Pd thickness. As a result, a high sensor sensitivity of 6.1 × 10 6 % at 5% H 2 concentration was obtained using a 1-nm-thick Pd-decorated IGZO film. Comparative studies with a zinc oxide (ZnO) counterpart showed that the Nd of IGZO (8 × 10 18 cm -3 ) is significantly higher than that of ZnO (2 × 10 16 cm -3 ), indicating a closer location for the Fermi level of IGZO to the conduction band. Therefore, a relatively small amount of electron-donating H 2 was required to overcome the energy barrier in IGZO. Consequently, the 1-nm-thick Pd-decorated IGZO sensor responded to a gas level as low as 0.01% (100 ppm) and demonstrated a 70-fold higher sensitivity compared with ZnO sensor at all H 2 concentrations.
Strong interactions between excitons are a characteristic feature of two-dimensional (2D) semiconductors, determining important excitonic properties, such as exciton lifetime, coherence, and ...photon-emission efficiency. Rhenium disulfide (ReS2), a member of the 2D transition-metal dichalcogenide (TMD) family, has recently attracted great attention due to its unique excitons that exhibit excellent polarization selectivity and coherence features. However, an in-depth understanding of exciton-exciton interactions in ReS2 is still lacking. Here we used ultrafast pump-probe spectroscopy to study exciton-exciton interactions in monolayer (1L), bilayer (2L), and triple layer ReS2. We directly measure the rate of exciton-exciton annihilation, a representative Auger-type interaction between excitons. It decreases with increasing layer number, as observed in other 2D TMDs. However, while other TMDs exhibit a sharp weakening of exciton-exciton annihilation between 1L and 2L, such behavior was not observed in ReS2. We attribute this distinct feature in ReS2 to the relatively weak interlayer coupling, which prohibits a substantial change in the electronic structure when the thickness varies. This work not only highlights the unique excitonic properties of ReS2 but also provides novel insight into the thickness dependence of exciton-exciton interactions in 2D systems.
In the originally published HTML and PDF versions of this article, Figs. 3g and 4d contained typesetting errors affecting the way the data points were displayed. This has now been corrected in the ...HTML and PDF versions.
This paper extends the minimum-chi-square estimation for affine term structure models to a regime switching framework, and corrects the estimation bias in the regime switching dynamic term structure ...model. Biases arise as a result of highly persistent bond yields, and bias correction changes the decomposition of medium- and long-term forward rates. The bias-corrected expected short rate accounts for the pronounced moves in forward rates during the 1979–1982 monetary experiment and the financial crisis. The bias-corrected term premium becomes counter-cyclical and more negatively correlated with the short-term yield. Monte Carlo simulation shows that the decomposition of forward rates is more accurate after bias correction.
This paper studies the dynamics of market integration in government bond markets. We utilise a new approach based on Pukthuanthong and Roll (2009) to investigate time-varying integration in 38 ...markets. We explore the impact of crisis periods, alongside differences in sample length, region, development and whether EMU and EU markets show obvious different integration from non-EU markets. Finally, we examine the effects of bonds' maturities on market integration. Considering the effects of factor heteroscedasticity and contagion during crisis periods, adjusted market integration is notably higher than implied by the Pukthuanthong and Roll (2009) measure. Developed markets experience increasing market integration over time, more than emerging markets. Most emerging markets provide little evidence of greater market integration. The EMU markets become almost fully integrated after the introduction of the Euro. Market integration also increases with maturity.
•This paper applies the Qin et al. (2022) approach to adjust biases in Pukthuanthong and Roll (2009) during financial crises.•We analyze the dynamics of government bond market integration, considering regions, bond maturity and market types.•We find that the method of Pukthuanthong and Roll (2009) underestimate the level of market integration during crises.•Developed markets experience increasing market integration over time but most emerging markets are still highly segmented.•After the introduction of the Euro, EMU markets become almost fully integrated until a dramatic drop following the GFC.
. Recent event-based analyses of transient neural activities have characterized the oscillatory bursts as a neural signature that bridges dynamic neural states to cognition and behaviors. Following ...this insight, our study aimed to (1) compare the efficacy of common burst detection algorithms under varying signal-to-noise ratios and event durations using synthetic signals and (2) establish a strategic guideline for selecting the optimal algorithm for real datasets with undefined properties.
We tested the robustness of burst detection algorithms using a simulation dataset comprising bursts of multiple frequencies. To systematically assess their performance, we used a metric called 'detection confidence', quantifying classification accuracy and temporal precision in a balanced manner. Given that burst properties in empirical data are often unknown in advance, we then proposed a selection rule to identify an optimal algorithm for a given dataset and validated its application on local field potentials of basolateral amygdala recorded from male mice (n=8) exposed to a natural threat.
Our simulation-based evaluation demonstrated that burst detection is contingent upon event duration, whereas accurately pinpointing burst onsets is more susceptible to noise level. For real data, the algorithm chosen based on the selection rule exhibited superior detection and temporal accuracy, although its statistical significance differed across frequency bands. Notably, the algorithm chosen by human visual screening differed from the one recommended by the rule, implying a potential misalignment between human priors and mathematical assumptions of the algorithms.
Therefore, our findings underscore that the precise detection of transient bursts is fundamentally influenced by the chosen algorithm. The proposed algorithm-selection rule suggests a potentially viable solution, while also emphasizing the inherent limitations originating from algorithmic design and volatile performances across datasets. Consequently, this study cautions against relying solely on heuristic-based approaches, advocating for a careful algorithm selection in burst detection studies.
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