1,532 research outputs found

    Effectiveness of vaccination and quarantine policies to curb the spread of COVID-19

    Full text link
    A pandemic, the worldwide spread of a disease, can threaten human beings from the social as well as biological perspectives and paralyze existing living habits. To stave off the more devastating disaster and return to a normal life, people make tremendous efforts at multiscale levels from individual to worldwide: paying attention to hand hygiene, developing social policies such as wearing masks, social distancing, quarantine, and inventing vaccines and remedy. Regarding the current severe pandemic, namely the coronavirus disease 2019, we explore the spreading-suppression effect when adopting the aforementioned efforts. Especially the quarantine and vaccination are considered since they are representative primary treatments for block spreading and prevention at the government level. We establish a compartment model consisting of susceptible (S), vaccination (V), exposed (E), infected (I), quarantined (Q), and recovered (R) compartments, called SVEIQR model. We look into the infected cases in Seoul and consider three kinds of vaccines, Pfizer, Moderna, and AstraZeneca. The values of the relevant parameters are obtained from empirical data from Seoul and clinical data for vaccines and estimated by Bayesian inference. After confirming that our SVEIQR model is plausible, we test the various scenarios by adjusting the associated parameters with the quarantine and vaccination policies around the current values. The quantitative result obtained from our model could suggest a guideline for policy making on effective vaccination and social policies.Comment: 8 pages, 5 figure

    Enhancing photoluminescence quantum efficiency of metal halide perovskites by examining luminescence-limiting factors

    Get PDF
    Metal halide perovskites (MHPs) show superior optoelectronic properties, which give them the great potential for use in next generation light-emitting diodes (LEDs). In particular, their narrow emission linewidths can achieve ultrahigh color purity. However, the reported luminescence efficiency (LE) values are not high enough to be commercialized in displays and solid-state lightings. Moreover, the operational stability of LEDs associated with the overshooting of luminance and the high relative standard deviation of reported external quantum efficiencies are still problematic. In this perspective, we review photophysical factors that limit the photoluminescence quantum efficiency of perovskite-based LEDs. These factors are categorized into (i) weak exciton binding, (ii) nonradiative recombinations, (iii) slow cooling of long-lived hot carriers, (iv) deep-level defects, and (v) interband transition rates. We then present various physicochemical methods to effectively overcome these luminescence-limiting factors. We finally suggest some useful research directions to further improve the LE of MHP emitters as core components in displays and solid-state lightings.

    Origin of Difference in the Reactivity of Aliphatic and Aromatic Guanidine-containing Pharmaceuticals Toward [18F]Fluorination: Coulombic Forces and Hydrogen Bonding

    Full text link
    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151351/1/bkcs11842.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151351/2/bkcs11842_am.pd

    Age group characteristics of children who visited a regional trauma center and analysis of factors affecting the severe trauma

    Get PDF
    Purpose The aim of this study was to analyze the age group characteristics and factors associated with the severe trauma in children who visited a regional trauma center. Methods We reviewed children aged 18 years or younger who visited a regional trauma center, equivalent to level 1 trauma centers in the United States, in Incheon, Korea from July 2014 through December 2019. They were classified by the age groups: preschoolers (0-6 years), schoolers (7-12 years), and adolescents (13-18 years). Across the 3 age groups, event profiles, severity, and outcomes of injury were compared. Multivariable logistic regressions were used to identify factors associated with the severe trauma, defined as the Injury Severity Score of 16 or higher. Results Among the total of 367 children, 74 (20.2%) were preschoolers, 73 (19.9%) were schoolers, and 220 (59.9%) were adolescents. The most common injury mechanisms in the preschoolers, schoolers, and adolescents were fall (40.5%), pedestrian collision (32.9%), and motorcycle accident (38.6%), respectively. The adolescents had the highest median Injury Severity Score (13 [interquartile range, 6-23]; P < 0.001). In the multivariable analyses, the Glasgow Coma Scale of 3-8 (odds ratio [OR], 14.60; 95% confidence interval, 5.40-39.42) had the highest OR for severe trauma, followed by injury in the abdomen or pelvic contents (OR, 11.61; 95% confidence interval, 4.66-28.89). Conclusion In pediatric trauma, the mechanism and severity of injury may differ according to age groups, with the severe trauma associated with injuries to the head and torso. It is advisable to have age group-specific approaches and strategies for injury prevention