Korea Development Institute

Does providing American vaccines overseas improve views of the United States? Do beneficiaries of donated shots change their opinions on foreign aid? Can the example of the United States providing aid lead to higher support for international assistance in other nations? Utilizing original panel data from a two-wave survey fielded in South Korea in 2021 and 2022, this paper finds no evidence that American shots, whether donated or purchased, lead to more positive views of the United States. However, we document a "pay it forward effect," where recipients of donated COVID-19 vaccines from the United States were more likely to pass on the generosity by supporting Korean vaccine aid to other countries in need. Information that the United States was supplying assistance to developing countries also made it more likely that vaccinated South Koreans would support their government donating vaccines abroad. This study provides evidence of second-order effects of vaccine aid that can benefit American interests by facilitating the timely distribution of vaccines across the globe, even when it does not improve the donor's image. The results highlight the role foreign aid can play in furthering international cooperation and call for broader criteria when evaluating its effect.

Abstract This study examines how consumer self-concept dimensions influence technology-mediated relationships in digital influencer marketing through structural equation modeling with 748 social media participants. We investigated how self-efficacy, self-assertion, social presence, self-esteem, and social conspicuousness affect social distance perception and para-social interaction formation with human influencers, while examining authenticity as a moderating variable. Results reveal that all self-concept dimensions significantly predict both social distance reduction and para-social interaction development with influencers. Notably, social conspicuousness emerged as the strongest predictor of social distance, while self-efficacy showed the strongest effect on para-social interaction. The study uncovered an asymmetric relationship pattern: while social distance strongly influenced recommendation intentions, it showed no significant effect on brand trust formation. Conversely, para-social interactions positively affected both brand trust and recommendation intentions. Brand trust demonstrated a robust relationship with recommendation intentions. Authenticity moderated four relationships, strengthening the self-assertion→social distance link under high authenticity conditions, while amplifying social presence effects on social distance and self-esteem/social conspicuousness effects on para-social interaction under low authenticity conditions. These findings contribute to management information systems literature by providing validated theoretical foundations for understanding technology-mediated self-concept manifestations in digital marketing, offering strategic implications for algorithmic personalization, consumer micro-segmentation, and adaptive content delivery mechanisms within social media marketing platforms.

We investigate the α and β effects in a rotating spherical plasma system relevant to astrophysical contexts. In particular, we focus on how kinetic and magnetic (current) helicities influence the magnetic diffusivity β. These coefficients were modeled using three complementary theoretical approaches. Direct numerical simulation (DNS) data (large-scale magnetic field B¯, turbulent velocity u, and turbulent magnetic field b) were then used to obtain the actual values of αEM−HM, βEM−HM, βvv−vw, and βbb+jb. Using these coefficients, we reconstructed B¯ and compared it with the DNS results. In the kinematic regime, where B¯ remains weak, all models agree well with DNS. In the nonlinear regime, however, the field reconstructed with βvv−vw alone deviates from DNS and grows without bound. Incorporating the turbulent magnetic diffusion term βbb+jb suppresses this unphysical growth and restores consistency. Specifically, B¯DNS saturates at approximately 0.23 in the nonlinear regime. The reconstructed B¯ using βEM−HM saturates at B¯∼0.3. When βvv−vw+bb+jb(=βvv−vw+βbb+jb) is used, B¯ varies from about 0.3 to 0.23. These results indicate that kinetic helicity reduces β (or provides a negative contribution), thereby amplifying B¯, whereas turbulent current helicity, together with turbulent magnetic and kinetic energies, enhances β, thus suppressing B¯ in the nonlinear regime. In this respect, the new form of β differs from the conventional one, which acts solely to diffuse the magnetic field.

BackgroundThis study aimed to investigate the initial site of calcification development in rotator cuff tendons using serial ultrasonographic evaluations.MethodsA total of 21 patients with de novo calcifications were included. Ultrasonography was used to assess calcifications in the rotator cuff tendons. The distance from the tendon insertion on the humerus to the calcification site was measured, along with the long and short diameters and the long-to-short diameter ratio.ResultsIn 19 patients (90%), calcifications were in direct contact with the tendon insertion on the humerus. In the remaining two patients (10%), the calcifications were located 1 mm proximal to the tendon insertion site. The mean long and short diameters of the calcifications were 9.4 ± 4.6 and 2.7 ± 1.2 mm (range: 3.0-17.0 and 1.0-4.5 mm), respectively. The mean long-to-short diameter ratio was 2.4 ± 2.2 mm (range: 1.8-10.0 mm). Regarding shoulder disorders, 1, 7, and 13 patients had a rotator cuff tendon tear, calcific tendinitis, and adhesive capsulitis, respectively.ConclusionsCalcifications in the rotator cuff tendons appear to originate at the tenoperiosteal junction or in close periosteal proximity and extend along the tendon axis.