A 37-40 GHz 6-Bits Switched-Filter Phase Shifter Using 150 nm GaN HEMT.

In this paper, we present a 6-bit phase shifter designed and fabricated using the 150 nm GaN HEMT process. The designed phase shifter operates within the n260 (37~40 GHz) band, as specified in the 5G NR standard, and employs the structure of a switched-filter phase shifter. By serially connecting six single-bit phase shifters, ranging from 180° to 5.625°, the designed phase shifter achieves a phase range of 360°. The fabricated phase shifter exhibits a minimum insertion loss of 5 dB and an RMS phase error of less than 5.36° within the 37 to 40 GHz. This phase shifter is intended for seamless integration with high-power RF circuits.

Successful control of COVID-19 outbreak through tracing, testing, and isolation: Lessons learned from the outbreak control efforts made in a metropolitan city of South Korea.

The first surge of coronavirus disease 2019 (COVID-19) cases began on June 27, 2020 in Gwangju metropolitan city, located in the southwestern part of South Korea, with a population of 1,501,000. Local governments and the Korean Center for Disease Control and Prevention immediately started an epidemiologic investigation and traced the contacts of patients using a wide variety of data sources, including location data from mobile devices, credit card transaction, and closed-circuit television footage. Until July 16, 2020, 138 community transmission cases and 10 infection clusters were identified across the city. Through contact tracing, epidemiologic relatedness was found in 136 (98.6%) of 138 cases. Our investigation showed how the extensive and meticulous contact tracing suppressed COVID-19 outbreak in a populated city.

Detection of Novel Coronavirus on the Surface of Environmental Materials Contaminated by COVID-19 Patients in the Republic of Korea.

This study aimed to determine the presence of SARS-CoV-2 on surfaces frequently touched by COVID-19 patients, and assess the scope of contamination and transmissibility in facilities where the outbreaks occurred. In the course of this epidemiological investigation, a total of 80 environmental specimens were collected from 6 hospitals (68 specimens) and 2 "mass facilities" (6 specimens from a rehabilitation center and 6 specimens from an apartment building complex). Specific reverse transcriptase-polymerase chain reaction targeting of RNA-dependent RNA polymerase, and envelope genes, were used to identify the presence of this novel coronavirus. The 68 specimens from 6 hospitals (A, B, C, D, E, and G), where prior disinfection/cleaning had been performed before environmental sampling, tested negative for SARS-CoV-2. However, 2 out of 12 specimens (16.7%) from 2 "mass facilities" (F and H), where prior disinfection/cleaning had not taken place, were positive for SARS-CoV-2 RNA polymerase, and envelope genes. These results suggest that prompt disinfection and cleaning of potentially contaminated surfaces is an effective infection control measure. By inactivating SARS-CoV-2 with disinfection/cleaning the infectivity and transmission of the virus is blocked. This investigation of environmental sampling may help in the understanding of risk assessment of the COVID-19 outbreak in "mass facilities" and provide guidance in using effective disinfectants on contaminated surfaces.

A High-Multi Target Resolution Focal Plane Array-Based Laser Detection and Ranging Sensor.

This paper introduces a digital-assisted multiple echo detection scheme, which utilizes the waste time of the full serial data readout period in a focal plane array (FPA)-based laser detection and ranging (LADAR) receiver. With the support of an external digital signal processor (DSP) and additional analog memory inserted into the receiver, the proposed readout scheme can effectively enhance multi-target resolution (MTR) three times higher than the conventional FPA-based LADAR, while maintaining low power consumption and a small area. A prototype chip was fabricated in a 0.18-µm CMOS process with an 8 × 8 FPA configuration, where each single receiver pixel occupied an area of 100 µm × 100 µm. The single receiver achieved an MTR of 20 ns with 7.47 mW power dissipation, an input referred noise current of 4.48 pA/√Hz with a bandwidth 530 MHz, a minimum detectable signal (MDS) of 340 nA, a maximum walk error of 2.2 ns, and a maximum non-linearity of 0.05% among the captured multiple echo images.

Expression, purification and crystallization of phosphoribosyl transferase from a mycobacteriophage.

Tuberculosis (TB) continues to remain a leading cause of death globally. Of particular concern is the emergence and rise in incidence of multidrug-resistant and extremely drug-resistant cases of TB. To counter this threat, it is important to explore alternative therapies, including phage therapy. Phage BTCU-1 specifically infects Mycobacterium spp. and kills the majority of them. Intriguingly, many proteins from the phage do not share high amino-acid sequence identity with proteins from species other than phages. Here, the expression, purification and crystallization of one such protein, a putative phosphoribosyl transferase from phage BTCU-1, is reported. The crystals belonged to space group C2221, with unit-cell parameters a = 59.71, b = 64.42, c = 65.32 Å, α = ß = γ = 90°. The crystals diffracted X-rays to 2.2 Šresolution.

Citation Analysis for Biomedical and Health Sciences Journals Published in Korea.

OBJECTIVES: A citation analysis of biomedical and health sciences journals was conducted based on their enlistment in journal databases to identify the factors contributing to the citation metrics. METHODS: Among the 1,219 academic journals managed by the National Center for Medical Information and Knowledge at the Korea Centers for Disease Control and Prevention, 556 journals were included for analysis as of July 2016. The characteristics of the journals include history years, publication media, language, open-access policy as well as the status enlisted in international and domestic databases, such as Science Citation Index (SCI), Scopus, Medline, PubMed Central, Embase, and Korea Citation Index (KCI). Six bibliometric measures were collected from SCI, Scopus, and KCI as of 2015, the most recent disclosure year. Analyses of group differences and influential factors were conducted using t-tests, Mann-Whitney tests, and multiple regression. RESULTS: Journal characteristics, such as history years, publication media, and open-access policy, were not significant factors influencing global or domestical citation of the journals. However, global citations were higher for SCI and Medline enlisted journals than for their counterparts. Among KCI journals, the KCI impact factors of journals published in English only were lower. CONCLUSIONS: Efforts by journals to be enlisted in international databases, especially in SCI and Medline, are critical to enhance their global circulation. However, articles published in English only hinder the use of domestic researchers. Different strategies are required for enhancing international and domestic readerships.

Uniaxial cyclic strain stimulates cell proliferation and secretion of interleukin-6 and vascular endothelial growth factor of human dermal fibroblasts seeded on chitosan scaffolds.

Human dermal fibroblasts were inoculated into chitosan sponge scaffolds coated with type I collagen and it might be developed as a dermal substitute and/or dressing material. The application of 14% uniaxial cyclic strain to the cellular scaffolds affected the characteristics of the seeded human dermal fibroblasts. Cyclic strain enhanced cellular proliferation, the activity of metalloproteinase-2, and the expression of extracellular matrix proteins such as fibronectin. Moreover, cyclic strain increased the expression of vascular endothelial growth factor (VEGF) and interleukin (IL)-6, which are critical to wound healing. Even under static culture (strain, 0%) following 14% cyclic strain, the expression of VEGF and IL-6, which had increased under 14% strain, was amplified or maintained for at least 3 days. Uniaxial cyclic strain may enhance the wound-healing potential of human dermal fibroblasts seeded on chitosan scaffolds through the changes in the cellular characteristics of the fibroblasts when the cellular scaffold is transplanted into skin wounds, especially chronic wounds such as diabetic wounds.

Identification of novel immunogenic proteins in pathogenic Haemophilus parasuis based on genome sequence analysis.

Haemophilus parasuis causes contagious porcine Glässer's disease, which is occurring worldwide and leads to severe losses in the pig industry. To identify novel antigen candidates against this disease, 22 surface-exposed or secreted proteins were selected from the annotated H. parasuis genome by reverse vaccinology strategy. Expression of these proteins in Escherichia coli was attempted. Immunogenicity of the expressed candidates was assessed using Western blot analysis with mouse-derived antiserum prepared with whole bacteria of H. parasuis serovar 4 or 5. Three ABC-type transporters (OppA, YfeA and PlpA) and 1 curli protein assembly (CsgG) were identified as potent immunogenic proteins. The proteins show cross-reactions when tested with sera raised against serovars 4 and 5 of H. parasuis.

Rapid dissemination of newly introduced Plasmodium vivax genotypes in South Korea.

Reemerged Plasmodium vivax malaria in South Korea has not yet been eradicated despite continuous governmental efforts. It has rather become an endemic disease. Our study aimed to determine the genetic diversity in P. vivax merozoite surface protein-1 (PvMSP-1) and circumsporozoite protein (PvCSP) genes over an extended period after its reemergence to its current status. Sequence analysis of PvMSP-1 gene sequences from the 632 P. vivax isolates during 1996-2007 indicates that most isolates recently obtained were different from isolates obtained in the initial reemergence period. There was initially only one subtype (recombinant) present but its subtypes have varied since 2000; six MSP-1 subtypes were recently found. A similar variation was observed by CSP gene analysis; a new CSP subtype was found. Understanding genetic variation patterns of the parasite may help to analyze trends and assess extent of endemic malaria in South Korea.

Timeliness of national notifiable diseases surveillance system in Korea: a cross-sectional study.

BACKGROUND: With the increase of international travels, infectious disease control is gaining a greater importance across regional borders. Adequate surveillance system function is crucial to prevent a global spread of infectious disease at the earliest stage. There have been limited reports on the characteristics of infectious disease surveillance in Asia. The authors studied the timeliness of the Korean National Notifiable Disease Surveillance System with regard to major notifiable diseases from 2001 to 2006. METHODS: Six notifiable infectious diseases reported relatively frequently were included in this study. Five diseases were selected by the criteria of reported cases > 100 per year: typhoid fever, shigellosis, mumps, scrub typhus, and hemorrhagic fever with renal syndrome. In addition, dengue fever was also included to represent an emerging disease, despite its low number of cases. The diseases were compared for the proportion notified within the recommended time limits, median time lags, and for the cumulative distribution of time lags at each surveillance step between symptom onset and date of notification to the Korea Centers for Disease Control and Prevention (KCDC). RESULTS: The proportion of cases reported in time was lower for disease groups with a recommended time limit of 1 day compared with 7 days (60%-70% vs. > 80%). The median time from disease onset to notification to KCDC ranged between 6 and 20 days. The median time from onset to registration at the local level ranged between 2 and 15 days. Distribution of time lags showed that main delays arose in the time from onset to diagnosis. There were variations in timeliness by disease categories and surveillance steps. CONCLUSION: Time from disease onset to diagnosis generally contributed most to the delay in reporting. It is needed to promote public education and to improve clinical guidelines. Rapid reporting by doctors should be encouraged, and unification of recommended reporting time limit can be helpful. Our study also demonstrates the utility of the overall assessment of time-lag distributions for disease-specific strategies to improve surveillance.