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

With the growth of chatbots, concerns about implementing artificial intelligence (AI) chatbots in educational settings have consistently arisen, especially for the purpose of language learning. This study introduced a task-based voice chatbot called “Ellie”, newly developed by the researchers, and examined the appropriateness of its task design and performance as an English conversation partner and students’ perceptions on using it in EFL class. Korean EFL learners (N = 314) aged 10–15 years performed three speaking tasks with Ellie in their school classroom. The participants took 9.63 turns per session on average using the first 1,000-word band, indicating that the chatbot highly encouraged students to engage in conversation, which rarely occurs in general EFL classes in Korea. The high task success rates (88.3%) showed the design appropriateness of both L2 tasks and operational intents in terms of users’ successful understanding and completeness of the given chatbot tasks. The participants’ responses to the survey not only supported the positive potential of the chatbot in EFL settings but also revealed limitations to be resolved. Future suggestions for advancing and implementing AI chatbots in EFL classrooms are discussed.

Imaging of liquids and cryogenic biological materials by electron microscopy has been recently enabled by innovative approaches for specimen preparation and the fast development of optimized instruments for cryo-enabled electron microscopy (cryo-EM). Yet, cryo-EM typically lacks advanced analytical capabilities, in particular for light elements. With the development of protocols for frozen wet specimen preparation, atom probe tomography (APT) could advantageously complement insights gained by cryo-EM. Here, we report on different approaches that have been recently proposed to enable the analysis of relatively large volumes of frozen liquids from either a flat substrate or the fractured surface of a wire. Both allowed for analyzing water ice layers which are several micrometers thick consisting of pure water, pure heavy water, and aqueous solutions. We discuss the merits of both approaches and prospects for further developments in this area. Preliminary results raise numerous questions, in part concerning the physics underpinning field evaporation. We discuss these aspects and lay out some of the challenges regarding the APT analysis of frozen liquids.

Material private information transmits through social networks. Using manually collected information on networks of alumni reunion cohorts, we show that hedge fund managers connected to directors of firms engaged in merger deals increase call-option holdings on target firms before deal announcements. Effects are larger when reunion events for connected cohorts occur just before announcements. Independent directors, directors with short tenure, and directors with low stock ownership are more likely to transmit information. Our results are robust to confounding factors and alternative specifications. These findings highlight the role of social networks as channels of private-information dissemination.

Analyzing porous (nano)materials via atom probe tomography has been notoriously difficult. Voids and pores act as concentrators of the electrostatic pressure, which results in premature specimen failure, and the electrostatic field distribution near voids leads to aberrations that are difficult to predict. In this study, we propose a new encapsulating method for porous samples using a low melting point Bi–In–Sn alloy, known as Field's metal. As a model material, we used porous iron made by direct-hydrogen reduction of single-crystalline wüstite. The complete encapsulation was performed using in situ heating on the stage of a scanning electron microscope. No visible corrosion nor dissolution of the sample occurred. Subsequently, specimens were shaped by focused ion-beam milling under cryogenic conditions at −190°C. The proposed approach is versatile and can be applied to provide good quality atom probe datasets from micro/nanoporous materials.

This paper presents a modularized autonomous pipeline inspection robot called MRINSPECT VII+, which we recently developed. MRINSPECT VII+ is aimed at inspect in-service urban gas pipelines with a diameter of 200 mm. The robot consists of five basic modules: driving, sensing, joint, and battery modules. For nondestructive testing (NDT), an NDT module can be added to the system. The driving module uses a multiaxial differential gear mechanism to provide traction forces to the robot. The sensor module recognizes the pipeline element using position-sensitive detector (PSD) sensors and a CCD camera. The control module contains a computing unit and manages the robot’s autonomous navigation. The battery module supplies power to the system. Each module is connected via backdrivable active joint modules, which provide flexibility while moving inside narrow pipelines. Additionally, the wireless communication module helps the system communicate with the ground station. We tested MRINSPECT VII+ in real pipeline environments and validated its feasibility successfully.

The impact of a drop train, a series of identical liquid drops separated by a constant distance, on a liquid pool initially generates a long slender cavity. However, the cavity soon collapses and turns into a shallow funnel. Here we theoretically model the dynamic profile of the elongated cavity and the steady shape of the funnel, which are then shown to agree well with experiment. When the liquid inertia plays a dominant role, the cavity assumes a parabolic profile that depends only on the drop diameter and the centre-to-centre spacing of adjacent drops. We consider the capillary forces as well as the drop impact force to obtain the shape of the funnel that persists once the elongated cavity collapses. Our study allows for predicting the interfacial morphology by the impact of a drop train and designing impact conditions useful for semiconductor cleaning processes.

The aeroacoustic source mechanism of a deep rectangular cavity, which has an aspect ratio of $D/L=2.632$ and is subjected to a turbulent boundary layer of $\theta /L=0.0345$ at a Mach number of 0.2, is investigated by using a high-order accurate large-eddy simulation. The primary aim of this study is to provide an improved understanding of the fluid–acoustic coupling mechanism that triggers a self-sustained acoustic resonance in a deep cavity. Various analysis methods, which include Doak's momentum potential theory that allows for the separation of hydrodynamic and acoustic components, are used to provide highly detailed investigations and findings. The vortex dynamics near the cavity opening region is investigated as the potential primary source of noise generation. In addition, the noise generation mechanism is quantitatively explained by the onset of the separation region near the downstream corner that ensues from the synchronised shear layer–wall interaction. The current work extensively focuses on the fluid–acoustic coupling mechanism, and it is found that the acoustic resonance favourably modulates the hydrodynamic fluctuation near the upstream corner of the cavity. Furthermore, the current study also suggests that nonlinear interactions between fundamental acoustic resonance and higher harmonics are plausible. Based on the discussions provided in this paper, a semi-empirical model to predict the critical free stream velocity at which a strong fluid–acoustic coupling occurs as a function of cavity geometry and inflow boundary-layer property is proposed.

Legumes are rich sources of essential nutrients, and their potential health benefits were reported in many studies. Several studies showed a positive effect of legumes on obesity, but randomised clinical trials are limited in the Korean population. The present intervention study investigated the impact of legumes on body weight in obese Korean subjects. A total of 400 participants (BMI ≥ 25 kg/m2) were randomised into two groups. The legume-enriched diet (LD) group replaced one-third of their refined rice consumption with legumes three times per day as a carbohydrate source. In contrast, the usual diet (UD) group consumed their UD. The mean weight loss at 12 weeks was 2·87 (sem 0·21) kg and 0·17 (sem 0·11) kg in the LD and UD, respectively, which was significantly different between the groups (P < 0·001). HDL-cholesterol and adiponectin levels were increased, and levels of glucose, insulin, TAG, and 8-epi-PGF2α and the homoeostasis model assessment of insulin resistance (IR) index value decreased at 12 weeks compared with baseline in the LD. The consumption of legumes may accelerate weight loss accompanied by regulation of adiponectin and 8-epi-PGF2α in obese subjects. In particular, legumes seemed to induce significant changes in BMI by increasing adiponectin in females. Additionally, increases in plasma adiponectin due to greater substantial weight loss may be related to the improvement in IR.

Liquids can invade fibrous porous media when the fibres are either wettable or soluble, and the infiltration rate can differ depending on spatial distribution of fibres as well as liquid properties. With continuing developments in dissolution-driven release mechanisms of porous drugs and chemical pattern formations, the understanding of how liquids spontaneously infiltrate into soluble fibrous media is strongly called for. Here we show that unlike capillarity-driven insoluble wicking (exhibiting diffusive growth of wetting distance with time), the wicking distance in soluble porous media grows linearly with time as dominated by liquid viscosity rather than surface tension. Such soluble wicking is highly sensitive to flow orientation relative to fibre alignment, so that it arises only in the crosswise direction while being strongly inhibited in the lengthwise direction. We present a theoretical model to explain the experimentally measured wicking rates in soluble porous media.

Two advanced, automated crystal orientation mapping techniques suited for nanocrystalline materials—precession electron diffraction (PED) in transmission electron microscopy (TEM) and on-axis transmission Kikuchi diffraction (TKD) in scanning electron microscopy (SEM)—are evaluated by comparing the orientation maps obtained from the identical location on a 30 nm-thick nanocrystalline tungsten (W) thin film. A side-by-side comparison of the orientation maps directly showed that the large-scale orientation features are almost identical. However, there are differences in the fine details, which arise from the fundamentally different nature of the spot pattern and Kikuchi line pattern in terms of the excitation volume and the angular resolution. While TEM-PED is more reliable to characterize grains oriented along low-index zone axes, the high angular resolution of SEM-TKD allows the detection of small misorientation between grains and thus yields better quantification and statistical analysis of grain orientation. Given that both TEM-PED and SEM-TKD orientation mapping techniques are complementary tools for nanocrystalline materials, one can be favorably selected depending on the requirements of the analysis, as they have competitive performance in terms of angular resolution and texture quantification.

Given the dynamic characteristic of an individual’s drinking behaviours, comprehensive consideration of alcohol consumption variation using repeated measures may improve insight into the nature of its association with blood pressure (BP) change. We examined the association between longitudinal alcohol consumption (trajectory and quantity) and changes in BP and pulse pressure (PP) among Korean aged ≥ 40 years living in rural areas. Totally, 1682 hypertension-free participants who completed all three health examinations (median, 5·3 years) were included. All three visits were used to determine the cumulative trajectory of and quantity of alcohol consumption and the latest two visits and the last visit were used for the recent trajectory and the most recent quantity of alcohol consumption, respectively. Changes in BP and PP from the baseline to the third visit were used as outcome. In men, ≥30 ml/d cumulative average alcohol consumption was associated with the greatest increase in systolic BP (SBP) in both baseline outcome-unadjusted (2·9 mmHg, P = 0·032) and -adjusted models (3·6 mmHg, P = 0·001), and the given association for the most recent alcohol consumption was observed in the baseline outcome-adjusted model (3·9 mmHg, P = 0·003). For PP, similar associations were observed only in the baseline outcome-adjusted model. No meaningful associations in diastolic BP in men and any BP or PP in women existed. The quantity of alcohol consumption rather than the trajectory may be significantly related to raised SBP, and a possible short-term influence of the most recent alcohol consumption may exist when baseline SBP is adjusted in men.

This paper deals with pricing formulae for a European call option and an exchange option in the case where underlying asset price processes are represented by stochastic delay differential equations with jumps (hereafter “SDDEJ”). We introduce a new model in which Poisson jumps are added in stochastic delay differential equations to capture behaviors of an underlying asset process more precisely. We derive explicit pricing formulae for the European call option and the exchange option by proving a Lemma on the conditional expectation. Finally, we show that our “SDDEJ” model is meaningful through some numerical experiments and discussions.

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