Brown dwarfs are failed stars with very low mass (13–75 Jupiter mass) and an effective temperature lower than 2 500 K. Their mass range is between Jupiter and red dwarfs. Thus, they play a key role in understanding the gap in the mass function between stars and planets. However, due to their faint nature, previous searches are inevitably limited to the solar neighbourhood (20 pc). To improve our knowledge of the low mass part of the initial stellar mass function and the star formation history of the Milky Way, it is crucial to find more distant brown dwarfs. Using James Webb Space Telescope (JWST) COSMOS-Web data, this study seeks to enhance our comprehension of the physical characteristics of brown dwarfs situated at a distance of kpc scale. The exceptional sensitivity of the JWST enables the detection of brown dwarfs that are up to 100 times more distant than those discovered in the earlier all-sky infrared surveys. The large area coverage of the JWST COSMOS-Web survey allows us to find more distant brown dwarfs than earlier JWST studies with smaller area coverages. To capture prominent water absorption features around 2.7 ${\unicode{x03BC}}$m, we apply two colour criteria, $\text{F115W}-\text{F277W}+1\lt\text{F277W}-\text{F444W}$ and $\text{F277W}-\text{F444W}\gt\,0.9$. We then select point sources by CLASS_STAR, FLUX_RADIUS, and SPREAD_MODEL criteria. Faint sources are visually checked to exclude possibly extended sources. We conduct SED fitting and MCMC simulations to determine their physical properties and associated uncertainties. Our search reveals 25 T-dwarf candidates and 2 Y-dwarf candidates, more than any previous JWST brown dwarf searches. They are located from 0.3 to 4 kpc away from the Earth. The spatial number density of 900–1 050 K dwarf is $(2.0\pm0.9) \times10^{-6}\text{ pc}^{-3}$, 1 050–1 200 K dwarf is $(1.2\pm0.7) \times10^{-6}\text{ pc}^{-3}$, and 1 200–1 350 K dwarf is $(4.4\pm1.3) \times10^{-6}\text{ pc}^{-3}$. The cumulative number count of our brown dwarf candidates is consistent with the prediction from a standard double exponential model. Three of our brown dwarf candidates were detected by HST, with transverse velocities $12\pm5$, $12\pm4$, and $17\pm6$ km s$^{-1}$. Along with earlier studies, the JWST has opened a new window of brown dwarf research in the Milky Way thick disk and halo.

Fast radio bursts (FRBs) are millisecond-duration radio waves from the Universe. Even though more than 50 physical models have been proposed, the origin and physical mechanism of FRB emissions are still unknown. The classification of FRBs is one of the primary approaches to understanding their mechanisms, but previous studies classified conventionally using only a few observational parameters, such as fluence and duration, which might be incomplete. To overcome this problem, we use an unsupervised machine-learning model, the Uniform Manifold Approximation and Projection to handle seven parameters simultaneously, including amplitude, linear temporal drift, time duration, central frequency, bandwidth, scaled energy, and fluence. We test the method for homogeneous 977 sub-bursts of FRB 20121102A detected by the Arecibo telescope. Our machine-learning analysis identified five distinct clusters, suggesting the possible existence of multiple different physical mechanisms responsible for the observed FRBs from the FRB 20121102A source. The geometry of the emission region and the propagation effect of FRB signals could also make such distinct clusters. This research will be a benchmark for future FRB classifications when dedicated radio telescopes such as the square kilometer array or Bustling Universe Radio Survey Telescope in Taiwan discover more FRBs than before.

This study presents the first Korean records of two subtropical fish species, Pseudojuloides paradiseus and Diplogrammus xenicus, collected around Jeju-do Island, as well as one boreal fish species, Erilepis zonifer, collected in Busan (approximately 200 km away from Jeju-do Island). In this study, we discuss the implications of the species’ habitat range expansion. Previously, P. paradiseus was known as an endemic species of Japan, while D. xenicus was known to inhabit the Eastern Indian Ocean and the Pacific Ocean excluding around the equator, and E. zonifer was only known to inhabit the Pacific Ocean between eastern Japan and the western USA. Their habitat range expansions might be attributed to the expansion of the Tsushima Warm Current at the surface layer and/or the North Korean Cold Current at the bottom layer. Our findings may suggest that habitat of marine fish is being changed continuously by climate change or oceanic currents. Therefore, it needs to conduct integrated and systematic monitoring of fish fauna to response changing marine biodiversity.

Over the past several decades, clay minerals have been applied in various bio-fields such as drug and drug additives, animal medicine and feed additives, cosmetics, biosensors, etc. Among various research areas, however, the medical application of clay minerals is an emerging field not only in academia but also in industry. In particular, cationic and anionic clays have long been considered as drug delivery vehicles for developing advanced drug delivery systems (DDSs), which is the most important of the various research fields including new drugs and medicines, in vitro and in vivo diagnostics, implants, biocompatible materials, etc., in nanomedicine. These applications are obviously related to global issues such as improvements in welfare and quality of life with life expectancy increasing. Many scientists, therefore, in various disciplines, such as clay mineralogy, material chemistry, molecular biology, pharmacology, and medical science, have been endeavoring to find solutions to such global issues. One of the strategic approaches is probably to explore new drugs possessing intrinsic therapeutic effects or to develop advanced materials with theranostic functions. With this is mind, discussions of examples of cationic and anionic clays with bio- and medical applications based on nanomedicine are relevant. In this tutorial review, nanomedicine based on clay minerals are described in terms of synthetic strategies of clay nanohybrids, in vitro and in vivo toxicity, biocompatibility, oral and injectable medications, diagnostics, theranosis, etc.

The ongoing pandemic, COVID-19 (SARS-CoV-2), has afflicted millions of people around the world, necessitating that the scientific community work, diligently and promptly, on suitable medicaments. Although vaccination programs have been run globally, the new variants of COVID-19 make it difficult to restrict the spread of the virus by vaccination alone. The combination of vaccination with anti-viral drug formulation is an ideal strategy for tackling the current pandemic situation. Drugs approved by the United States Food and Drug Administration (FDA), such as Remdesivir, have been found to be of little or no benefit. On the other hand, re-purposing of FDA-approved drugs, such as niclosamide (NIC), has offered promise but its applicability is limited due to its poor aqueous solubility and, therefore, low bioavailability. With advanced nano-pharmaceutical approaches, re-purposing this drug in a suitable drug-carrier for a better outcome may be possible. In the current study, an attempt was made to explore the loading of NIC into exfoliated layered double hydroxide nanoparticles (X-LDH NPs); prepared NIC-X-LDH NPs were further modified with eudragit S100 (ES100), an enteric coating polymer, to make the final product, ES100-NIC-X-LDH NPs, to improve absorption by the gastro/intestinal tract (GIT). Furthermore, Tween 60 was added as a coating on ES100-NIC-X-LDH NPs, not just to enhance its in vitro and in vivo stability, but also to enhance its mucoadhesive property, and to obtain, ultimately, better in vivo pharmacokinetic (PK) parameters upon oral administration. Release of NIC from Tween 60-ES100-NIC-X-LDH NPs was found to be greater under gastro/intestinal solution within a shorter period of time than the uncoated samples. The in vivo analysis revealed that Tween 60-ES100-NIC-X-LDH NPs were able to maintain a therapeutically relevant NIC plasma concentration in terms of PK parameters compared to the commercially available Yomesan®, proving that the new formulation might prove to be an effective oral drug-delivery system to deal with the SARS-CoV-2 viral infections. Further studies are required to ensure their safety and anti-viral efficacy.

Focus here is placed on the pharmaceutical and biomedical applications of novel clay-drug hybrid materials categorized by methods of administration. Clay minerals have been used for many years as pharmaceutical and medicinal ingredients for therapeutic purposes. A number of studies have attempted to explore clay-drug hybrid materials for biomedical applications with desired functions, such as sustained release, increased solubility, enhanced adsorption, mucoadhesion, biocompatibility, targeting, etc. The present review attempts not only to summarize the state-of-the-art of clay-drug hybrid materials and their advantages, depending on the methods of administration, but also to deal with challenges and future perspectives of clay mineral-based hybrids for biomedical applications.

Brain ageing, the primary risk factor for cognitive impairment, occurs because of the accumulation of age-related neuropathologies. Identifying effective nutrients that increase cognitive function may help maintain brain health. Tomatoes and lemons have various bioactive functions and exert protective effects against oxidative stress, ageing and cancer. Moreover, they have been shown to enhance cognitive function. In the present study, we aimed to investigate the effects of tomato and lemon ethanolic extracts (TEE and LEE, respectively) and their possible synergistic effects on the enhancement of cognitive function and neurogenesis in aged mice. The molecular mechanisms underlying the synergistic effect of TEE and LEE were investigated. For the in vivo experiment, TEE, LEE or their mixture was orally administered to 12-month-old mice for 9 weeks. A single administration of either TEE or LEE improved cognitive function and neurogenesis in aged mice to some extent, as determined using the novel object recognition test and doublecortin immunohistochemical staining, respectively. However, a significant enhancement of cognitive function and neurogenesis in aged mice was observed after the administration of the TEE + LEE mixture, which had a synergistic effect. N-methyl-d-aspartate receptor 2B, postsynaptic density protein 95, and brain-derived neurotrophic factor (BDNF) levels and tropomyosin receptor kinase B (TrkB)/extracellular signal-regulated kinase (ERK) phosphorylation also synergistically increased after the administration of the mixture compared with those in the individual treatments. In conclusion, compared with their separate treatments, treatment with the TEE + LEE mixture synergistically improved the cognitive function, neurogenesis and synaptic plasticity in aged mice via the BDNF/TrkB/ERK signalling pathway.

In this article, we explore whether hierarchy and linearity conspire to affect agreement. The data come from an experimental study of honorific agreement between verbal si and coordinate subjects in Korean. We focus on computing the mismatch driven by honorifically mixed conjuncts. Unlike South Slavic gender agreement, Korean has neither Resolved Agreement nor First Conjunct Agreement. Only Last Conjunct Agreement is attested in Korean honorification. We show that honorific agreement within coordinate subjects is triggered only when the honorific verbal si appears, which is substantially different from the case with the honorific nominal nim. We also show that acceptability significantly decreases when the last conjunct of coordinate subjects is incongruous with an honorific verb. We thus argue that verbal honorific agreement with Korean coordinate subjects is sensitive to linear order, mimicking South Slavic gender agreement.

Blood carotenoid concentration measurement is considered the gold standard for fruit and vegetable (F&V) intake estimation; however, this method is invasive and expensive. Recently, skin carotenoid status (SCS) measured by optical sensors has been evaluated as a promising parameter for F&V intake estimation. In this cross-sectional study, we aimed to validate the utility of resonance Raman spectroscopy (RRS)-assessed SCS as a biomarker of F&V intake in Korean adults. We used data from 108 participants aged 20–69 years who completed SCS measurements, blood collection and 3-d dietary recordings. Serum carotenoid concentrations were quantified using HPLC, and dietary carotenoid and F&V intakes were estimated via 3-d dietary records using a carotenoid database for common Korean foods. The correlations of the SCS with serum carotenoid concentrations, dietary carotenoid intake and F&V intake were examined to assess SCS validity. SCS was positively correlated with total serum carotenoid concentration (r = 0·52, 95 % CI = 0·36, 0·64, P < 0·001), serum β-carotene concentration (r = 0·60, 95 % CI = 0·47, 0·71, P < 0·001), total carotenoid intake (r = 0·20, 95 % CI = 0·01, 0·37, P = 0·04), β-carotene intake (r = 0·30, 95 % CI = 0·11, 0·46, P = 0·002) and F&V intake (r = 0·40, 95 % CI = 0·23, 0·55, P < 0·001). These results suggest that SCS can be a valid biomarker of F&V intake in Korean adults.

In this paper we study a class of optimal stopping problems under g-expectation, that is, the cost function is described by the solution of backward stochastic differential equations (BSDEs). Primarily, we assume that the reward process is $L\exp\bigl(\mu\sqrt{2\log\!(1+L)}\bigr)$ -integrable with $\mu>\mu_0$ for some critical value $\mu_0$ . This integrability is weaker than $L^p$ -integrability for any $p>1$ , so it covers a comparatively wide class of optimal stopping problems. To reach our goal, we introduce a class of reflected backward stochastic differential equations (RBSDEs) with $L\exp\bigl(\mu\sqrt{2\log\!(1+L)}\bigr)$ -integrable parameters. We prove the existence, uniqueness, and comparison theorem for these RBSDEs under Lipschitz-type assumptions on the coefficients. This allows us to characterize the value function of our optimal stopping problem as the unique solution of such RBSDEs.

Background: Although small- and medium-sized hospitals comprise most healthcare providers in South Korea, data on antibiotic usage is limited in these facilities. We evaluated the pattern of antibiotic usage and its appropriateness in hospitals with <400 beds in South Korea. Methods: A multicenter retrospective study was conducted in 10 hospitals (6 long-term care hospitals, 3 acute-care hospitals, and 1 orthopedic hospital), with <400 beds in South Korea. We analyzed patterns of antibiotic prescription and their appropriateness in the participating hospitals. Data on the monthly antibiotic prescriptions and patient days for hospitalized patients were collected using electronic databases from each hospital. To avoid the effect of the COVID-19 pandemic, data were collected from January to December 2019. For the evaluation of the appropriateness of the prescription, 25 patients under antibiotic therapy were randomly selected at each hospital over 2 separate periods. Due to the heterogeneity of their characteristics, the orthopedics hospital was excluded from the analysis. The collected data were reviewed, and the appropriateness of antibiotic prescriptions was evaluated by 5 specialists in infectious diseases (adult and pediatric). Data from 2 hospitals were assigned to each specialist. The appropriateness of antibiotic prescriptions was evaluated from 3 aspects: route of administration, dose, and class. If the 3 aspects were ‘optimal,’ the prescription was considered ‘optimal.’ If only the route was ‘optimal,’ and the dose and/or class was ‘suboptimal,’ but not ‘inappropriate,’ it was considered ‘suboptimal.’ If even 1 aspect was ‘inappropriate,’ it was classified as ‘inappropriate.’ Results: The most commonly prescribed antibiotics in long-term care hospitals was fluoroquinolone, followed by β-lactam/β-lactamase inhibitor (antipseudomonal). In acute-care hospitals, these were third-generation cephalosporin, followed by first-generation cephalosporin and second-generation cephalosporin. The major antibiotics that were prescribed in the orthopedics hospital was first-generation cephalosporin. Only 2.3% of the antibiotics were administered inappropriately. In comparison, 15.3% of patients were prescribed an inappropriate dose. The proportion of inappropriate antibiotic prescriptions was 30.6% of the total antibiotic prescriptions. Conclusions: The antibiotic usage patterns vary between small- and medium-sized hospitals in South Korea. The proportion of inappropriate prescriptions exceeded 30% of the total antibiotic prescriptions.

Funding: None

Disclosures: None

Adverse effects of intoxicated driving have been well documented over the years, with clear conclusions. In addition, it is evident that the cognitive and neurological functions and reaction times deteriorate with the consumption of alcohol. Addressing the lack of literature on the subject, this paper focuses on studying the effects of alcohol on manoeuvring, navigational and decision-making ability in ship navigation. Ten participants – five cadets and five experienced navigation officers – volunteered and carried out a standard manoeuvre using a computer-controlled vessel simulator, under three different blood alcohol concentrations (0⋅00%, 0⋅05% and 0⋅08% BAC). Results from the simulations were used to assess the performance and the decision-making ability of participants under the influence of alcohol. In addition, the responses and behaviour of the simulated vessel when the navigators were intoxicated were analysed. Workload experienced by participants during the simulations were also assessed using the NASA Task Load Index. Findings of this preliminary study proved that the ability to make the correct decisions at the right time was drastically deteriorated when the blood alcohol concentration was increased.

The caridean shrimp family Chlorotocellidae has so far not been reported from Korean waters. One of the four genera in the family is herein reported, based on the species Anachlorocurtis commensalis. Specimens were collected from antipatharian black corals by scuba diving at depths ranging from 20–60 m from three localities: Jejudo Island (33°13′N) between the South Sea of Korea and the north-eastern East China Sea, Namhyeongjedo Islet (34°53′N) in the Korea Strait, and Dokdo Island (37°15′N) in the East Sea. The species had previously been reported in tropical to subtropical latitudes in the western Pacific, with known records from southern Taiwan (up to 21°55′N) to central Japan (down to 34°50′N). The species is thus recorded for the first time from a temperate region in the western Pacific Ocean, postulated to be influenced by a branch of the Kuroshio Warm Current.

Background: After the Middle East respiratory syndrome coronavirus outbreak in Korea in 2015, the government newly established the additional reimbursement for infection prevention to encourage infection control activities in the hospitals. The new policy was announced in December 2015 and was implemented in September 2016. We evaluated how infection control activities improved in hospitals after the change of government policy in Korea. Methods: Three cross-sectional surveys using the WHO Hand Hygiene Self-Assessment Framework (HHSAF) were conducted in 2013, 2015, and 2017. Using multivariable linear regression model including hospital characteristics, we analyzed the changes in total HHSAF scores according to the survey time. Results: In total, 32 hospitals participated in the survey in 2013, 52 in 2015, and 101 in 2017. The number of inpatient beds per infection control professionals decreased from 324 in 2013 to 303 in 2015 and 179 in 2017. Most hospitals were at intermediate or advanced levels of progress (90.6% in 2013, 86.6% in 2015, and 94.1% in 2017). In a multivariable linear regression model, the total HHSAF scores were significantly associated with hospital teaching status (β coefficient of major teaching hospital, 52.6; 95% CI, 8.9–96.4; P = .018), bed size (β coefficient of 100-bed increase, 5.1; 95% CI, 0.3–9.8; P = .038), and survey time (β coefficient of 2017 survey, 45.1; 95% CI, 19.3–70.9; P = .001). Conclusions: After the national policy implementation, the number of infection control professionals increased, and the promotion of hand hygiene activities was strengthened in Korean hospitals.

Funding: None

Disclosures: None