JuHee Lee

Limits on WIMP-nucleon cross section with CsI(Tl) crystal detectors

The Korea Invisible Mass Search(KIMS) experiment presents new limits on WIMP-nucleon cross section using the data from an exposure of 3409 kgd taken with low background CsI(Tl) crystals at Yangyang underground laboratory. The most stringent limit on the spin dependent interaction for pure proton case is obtained. The DAMA signal region for both spin independent and spin dependent interactions for the WIMP mass higher than 20 GeV/c^2are excluded by the single experiment with crystal scintillators.

New Limits on Interactions between Weakly Interacting Massive Particles and Nucleons Obtained with CsI(Tl) Crystal Detectors

The Korea Invisible Mass Search (KIMS) experiment presents new limits on the weakly interacting massive particle (WIMP)-nucleon cross section using data from an exposure of 3409 kg.d taken with low-background CsI(Tl) crystals at the Yangyang Underground Laboratory. The most stringent limit on the spin-dependent interaction for a pure proton case is obtained. The DAMA signal region for both spin-independent and spin-dependent interactions for the WIMP masses greater than 20 GeV/c2 is excluded by the single experiment with crystal scintillators.

A Meta-Analysis of Fear of Falling Treatment Programs for the Elderly

This study examines the effectiveness of interventions for decreasing the fear of falling by synthesizing the results of individual studies of fear of falling prevention. The mean weighted effect sizes (MWES) of six studies are computed. The overall MWES is .21 (N = 957; 95% CI .068—.362). Results indicate that interventions are effective in reducing the fear of falling or increasing fall efficacy. The MWES is .249, .024, and .418 for the combined intervention, exercise intervention only, and hip protector groups, respectively. The MWES of the 3 months or less group was .000, and the 4-months group was .240. The MWES is .022, .228, and .418 for the facility-based, community-based, and home-based intervention groups, respectively. Overall, interventions were effective in decreasing fear of falling and increasing fall efficacy. Results suggest that the best outcome is obtained after 4 months, indicating that interventions need some time to obtain their effects.

Experiences among Undergraduate Nursing Students on High-fidelity Simulation Education: A Focus Group Study

Purpose: The purpose of this study was to explore experiences among undergraduate nursing students in a high-fidelity simulation education course for a semester. Method: The participants in this study were 10 nursing students in the senior classes and volunteers. Data collection was conducted using a focus group interview for 100 minutes, which was recorded on video tape. Transcribed data was analyzed through qualitative content analysis. Result: The results of this study were deduced as 4 codes and 22 themes. Study participants reported experiences due to the simulation method itself, interaction among peer group and personal experiences during high-fidelity simulation education. Additionally, experiences related to clinical application were examined. The participants indicated positive outcomes such as developing clinical judgment skills and confidence. Conclusion: Overall, the results of this study supported the usability and effectiveness of a high-fidelity simulation education method in undergraduate nursing curriculum. Further studies are needed to provide more reliable and valid educational information.

Prediction of fluid responsiveness in mechanically ventilated children undergoing neurosurgery

BACKGROUND The purpose of this study was to evaluate the clinical usefulness of static and dynamic variables for the prediction of fluid responsiveness in children under general anaesthesia. METHODS Thirty-three mechanically ventilated children received 10 ml kg(-1) colloid for 10 min while stable during surgery. Arterial pressure, heart rate, central venous pressure (CVP), and pleth variability index (PVI), in addition to variation in systolic pressure, pulse pressure (including Δdown and Δup), respiratory aortic blood flow velocity (ΔVpeak), and inferior vena cava diameter were measured before and after volume expansion. Patients were classified as responders to fluid loading if their stroke volume index (SVI) increased by at least 10%. RESULTS There were 15 volume responders and 18 non-responders. Of the variables examined, ΔVpeak (r=0.516, P=0.004) and PVI (r=0.49, P=0.004) before volume expansion were significantly correlated with changes in SVI. The receiver-operating characteristic (ROC) curve analysis showed that PVI and ΔVpeak predicted fluid responsiveness. Areas under the ROC curves of PVI and ΔVpeak were statistically larger than that of CVP (P=0.006 and 0.014, respectively). However, those of other variables were similar to that of CVP. CONCLUSIONS ΔVpeak and PVI can be used to predict fluid responsiveness in mechanically ventilated children under general anaesthesia. The other static and dynamic variables assessed in this study were not found to predict fluid responsiveness significantly in children. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov, NCT01364103.

Neutron beam test of CsI crystal for dark matter search

Abstract We have studied the response of Tl- and Na-doped CsI crystals to nuclear recoils and γs below 10 keV . The response of CsI crystals to nuclear recoil was studied with mono-energetic neutrons produced by the 3 H ( p , n ) 3 He reaction. This was compared to the response to Compton electrons scattered by 662 keV γ-ray. Pulse shape discrimination between the response to these γs and nuclear recoils was studied, and quality factors were estimated. The quenching factors for nuclear recoils were derived for both CsI(Na) and CsI(Tl) crystals.Abstract We have studied the response of Tl- and Na-doped CsI crystals to nuclear recoils and γs below 10 keV . The response of CsI crystals to nuclear recoil was studied with mono-energetic neutrons produced by the 3 H ( p , n ) 3 He reaction. This was compared to the response to Compton electrons scattered by 662 keV γ-ray. Pulse shape discrimination between the response to these γs and nuclear recoils was studied, and quality factors were estimated. The quenching factors for nuclear recoils were derived for both CsI(Na) and CsI(Tl) crystals.

Textile electrodes of jacquard woven fabrics for biosignal measurement

In the last few years, textile electrodes have become an interesting topic for physiological monitoring, steadily developing to be applied in innovative wearable sensing systems. The structure of textile electrodes can be fabricated by weaving, knitting, or embroidering conductive yarn and is now commercially available. The upgraded textile electrode is used in biosignal sensing and was designed in the form of a jacquard woven structure to measure the ECG. In the case of knit fabric, which has piezo‐resistive properties, the textile electrodes were developed by using the fabric’s flexible strain gauges in a bio‐monitoring system. However, the piezo‐resistive sensing fabrics have some shortcomings such as low dynamic range, poor repeatability, and performance deterioration after washing or repeated folding. Woven fabric, which is cloth woven in the warp and weft directions, has less strain properties and can be constructed more uniformly than knit fabric. Therefore, due to their more consistent woven structure, jacquard woven fabrics made with conductive yarn can be manufactured evenly on a large scale and consistently maintain their properties. The woven structure of jacquard electrodes consists of a double‐faced weave and is woven with a silver covering yarn in the weft direction. The proposed textile electrodes were composed of two groups made up of warps with either the unremoved 100% warps or the half‐removed 50% warps of jacquard woven electrodes that were convex or flat and were either with or without conductive paste. The ECG measurements for the textile electrodes were repeated three times in resting conditions. The convex jacquard electrodes of the half‐removed 50% warps with the conductive paste resulted in the most significant SNR improvement (33.67 dB). The purpose of this paper was to investigate a method to design jacquard woven electrodes uniformly on a large scale and to apply it feasibly to ECG measurement.

Comparison between ultrasound-guided supraclavicular and infraclavicular approaches for subclavian venous catheterization in children—a randomized trial

BACKGROUND Ultrasound (US)-guided subclavian vein (SCV) catheterization via the supraclavicular (SC) or infraclavicular (IC) approaches can be useful in children. The purpose of this study was to compare the efficacy of these approaches. METHODS This prospective, randomized study included 98 children who were <3 years old, and who were divided into two groups: the SC group (n=49) and the IC group (n=49). All SCV catheterizations were guided by US and performed by a single experienced anaesthesiologist. Data regarding puncture time, number of attempts, successful guidewire insertion, catheter insertion time, and complications were analysed. RESULTS The median puncture time was longer in the IC group than the SC group (48 vs 36 s, P=0.02). Multiple attempts (number of attempts >3) were more frequently required in the IC group than the SC group (24.5 vs 6.1%, P=0.01). The incidence of guidewire misplacement was higher in the IC group than that of the SC group [10 (20.4%) vs 0 (0%), P=0.001]. Catheterization was successfully performed in all patients. No pneumothoraces or arterial punctures occurred in either group. CONCLUSION During SCV catheterization under US guidance in paediatric patients, the SC approach yielded a shorter puncture time and decreased the incidence of guidewire misplacement when compared with the IC approach.

Study of the internal background of CsI(Tl) crystal detectors for dark matter search

A search for particle cold dark matter with CsIðTcÞ crystal is being prepared at the Cheong-Pyeong underground laboratory in Korea. The background spectra ofCsI ðTcÞ crystal detectors in a prototype shield were obtained. The lowest background count rate ofthe test sample ofcrystals is measured to be 64 :775:1 counts/keV/kg/day in the energy range of5–20 keV : Quantitative estimation ofresidual radioactive isotope in CsI ðTcÞ was made using the GEANT4 Monte Carlo simulation. Analysis results show that CsIðTcÞ crystal could be a good candidate for direct detection of WIMPs when the contamination level ofcesium radioisotopes is reduced to under a f mBq/kg. r 2003 Elsevier Science B.V. All rights reserved.

Polyethylene glycol bowel preparation does not eliminate the risk of acute renal failure: a population-based case-crossover study

BACKGROUND AND STUDY AIMS Polyethylene glycol (PEG) bowel preparations are regarded as effective and safe for colonoscopy; however, recent reports have indicated a risk of acute renal failure (ARF). This population-based case-crossover study evaluated the association between PEG and ARF in screening colonoscopy patients aged ≥ 50 years. PATIENTS AND METHODS Korean Health Insurance Review and Assessment Service (HIRA) claims data from 1 January 2005 to 31 December 2009 were used in the study. The study population consisted of patients aged ≥ 50 years who were first hospitalized for ARF following colonoscopy involving PEG bowel preparation. For each patient, PEG use in a 1-, 2-, or 4-week period prior to the first hospital admission date for ARF (hazard period) was compared with PEG use in four earlier 1-, 2-, or 4-week control periods. Conditional logistic regression analysis was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs), adjusting for concomitant medications that could induce ARF. RESULTS The total number of study patients was 1064 (59 % were male). A greater proportion of patients used PEG during the hazard period than during the control periods (for 4-week time window: 8.8 % vs. 3.2 %). The adjusted ORs for ARF incidence when applying the 1-, 2-, and 4-week periods were 3.1 (95 %CI 2.06 - 4.73), 2.5 (95 %CI 1.76 - 3.53), and 2.1 (95 %CI 1.61 - 4.85), respectively. CONCLUSIONS The use of PEG was associated with the risk of ARF. Adequate hydration and renal function monitoring should be assured before and after colonoscopy, regardless of the bowel preparation regimen used.