3,017 research outputs found

    Who are Cross-Border Online Shoppers?

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    Cross-border online purchase has been significantly increased throughout the world thanks to the development of transportation and technology. Understanding cross-border online shopping behavior in South Korea is particularly important due to its dramatic growth. Since 2010, cross-border online shopping has been increased by 40% every year (Korean Consumer Agency, 2014). This study is to enhance the understanding of cross-border online shopping behavior in South Korea. Based on the Theory of Reasoned Action (TRA), specifically, this study examined the relationships among consumer beliefs, attitude, subjective norms, and purchase intention for cross-border online shopping. This results of this research demonstrated that building a positive attitude toward cross-border online shopping, which was influenced by global orientation, ethnocentrism, and global brand beliefs, was the powerful antecedent of purchase intention for cross-border shopping

    Temperature-dependent evolutions of excitonic superfluid plasma frequency in a srong excitonic insulator candidate, Ta2_2NiSe5_5

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    We investigate an interesting anisotropic van der Waals material, Ta2_{2}NiSe5_{5}, using optical spectroscopy. Ta2_{2}NiSe5_{5} has been known as one of the few excitonic insulators proposed over 50 years ago. Ta2_{2}NiSe5_{5} has quasi-one dimensional chains along the aa-axis. We have obtained anisotropic optical properties of a single crystal Ta2_{2}NiSe5_{5} along the aa- and cc-axes. The measured aa- and cc-axis optical conductivities exhibit large anisotropic electronic and phononic properties. With regard to the aa-axis optical conductivity, a sharp peak near 3050 cm1^{-1} at 9 K, with a well-defined optical gap (ΔEI\Delta^{EI} \simeq 1800 cm1^{-1}) and a strong temperature-dependence, is observed. With an increase in temperature, this peak broadens and the optical energy gap closes around \sim325 K(TcEIT_c^{EI}). The spectral weight redistribution with respect to the frequency and temperature indicates that the normalized optical energy gap (ΔEI(T)/ΔEI(0)\Delta^{EI}(T)/\Delta^{EI}(0)) is 1(T/TcEI)21-(T/T_c^{EI})^2. The temperature-dependent superfluid plasma frequency of the excitonic condensation in Ta2_{2}NiSe5_{5} has been determined from measured optical data. Our findings may be useful for future research on excitonic insulators.Comment: 17 pages, 5 figure

    Coevolution underlies GPCR-G protein selectivity and functionality

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    G protein-coupled receptors (GPCRs) regulate diverse physiological events, which makes them as the major targets for many approved drugs. G proteins are downstream molecules that receive signals from GPCRs and trigger cell responses. The GPCR-G protein selectivity mechanism on how they properly and timely interact is still unclear. Here, we analyzed model GPCRs (i.e. HTR, DAR) and Gα proteins with a coevolutionary tool, statistical coupling analysis. The results suggested that 5-hydroxytryptamine receptors and dopamine receptors have common conserved and coevolved residues. The Gα protein also have conserved and coevolved residues. These coevolved residues were implicated in the molecular functions of the analyzed proteins. We also found specific coevolving pairs related to the selectivity between GPCR and G protein were identified. We propose that these results would contribute to better understandings of not only the functional residues of GPCRs and Gα proteins but also GPCR-G protein selectivity mechanisms. © 2021, The Author(s).1

    Accidental ingestion of E-cigarette liquid nicotine in a 15-month-old child: an infant mortality case of nicotine intoxication

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    Electronic cigarettes are novel tobacco products that are frequently used these days. The cartridge contains liquid nicotine and accidental poisoning, even with a small oral dose, endangers children. We present here a mortality case of a 15-month-old child who ingested liquid nicotine mistaking it for cold medicine. When the emergency medical technicians arrived, she was found to have pulseless electrical activity. Spontaneous circulation was restored after approximately 40 minutes of cardiopulmonary resuscitation. The cotinine level in her urine was 1,716 ng/mL. Despite intensive supportive care, severe anoxic brain injury was found on computed tomography and the child ultimately died. This fatality highlights the need for public health efforts to minimize such accidents

    MMP-Inhibitory Effects of Flavonoid Glycosides from Edible Medicinal Halophyte Limonium tetragonum

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    Limonium tetragonum has been well-known for its antioxidative properties as a halophyte. This study investigated the antimetastasis effect of solvent-partitioned L. tetragonum extracts (LTEs) and isolated compounds on HT1080 mouse melanoma cell model with a focus on matrix metalloproteinase (MMP) activity and TIMP and MAPK pathways. Upregulation and stimulation of MMPs result in elevated degradation of extracellular matrix which is part of several complications such as metastasis, cirrhosis, and arthritis. The anti-MMP capacity of LTEs was confirmed by their MMP-inhibitory effects, regulation of MMP and TIMP expression, and suppression of MAPK pathway. Among all tested LTEs, 85% aq. MeOH and n-BuOH were found to be most active fractions which later yielded two known flavonoid glycosides, myricetin 3-galactoside and quercetin 3-o-beta-galactopyranoside. Anti-MMP potential of the compounds was confirmed by their ability to regulate MMP expression through inhibited MAPK pathway activation. These results suggested that L. tetragonum might serve as a potential source of bioactive substances with effective anti-MMP properties

    The determination of dark adaptation time using electroretinography in conscious Miniature Schnauzer dogs

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    The optimal dark adaptation time of electroretinograms (ERG's) performed on conscious dogs were determined using a commercially available ERG unit with a contact lens electrode and a built-in light source (LED-electrode). The ERG recordings were performed on nine healthy Miniature Schnauzer dogs. The bilateral ERG's at seven different dark adaptation times at an intensity of 2.5 cd·s/m2 was performed. Signal averaging (4 flashes of light stimuli) was adopted to reduce electrophysiologic noise. As the dark adaptation time increased, a significant increase in the mean a-wave amplitudes was observed in comparison to base-line levels up to 10 min (p < 0.05). Thereafter, no significant differences in amplitude occured over the dark adaptation time. Moreover, at this time the mean amplitude was 60.30 ± 18.47 µV. However, no significant changes were observed for the implicit times of the a-wave. The implicit times and amplitude of the b-wave increased significantly up to 20 min of dark adaptation (p < 0.05). Beyond this time, the mean b-wave amplitudes was 132.92 ± 17.79 µV. The results of the present study demonstrate that, the optimal dark adaptation time when performing ERG's, should be at least 20 min in conscious Miniature Schnauzer dogs

    Recent Trend in the Incidence of Premalignant and Malignant Skin Lesions in Korea between 1991 and 2006

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    We evaluated the recent trend in the incidence of premalignant and malignant skin lesions between 1991 and 2006. Among 571,057 newly registered dermatology out-patients from our 8 affiliated university hospitals, 2,598 were diagnosed with a premalignant (899, 0.16%) or malignant skin lesions (1,699, 0.30%). Of 899 premalignant cases, 71.2% were actinic keratosis (AK), and 24.6% were Bowen's disease. Of 1,699 malignant cases, 46.2% were basal cell carcinoma, followed by squamous cell carcinoma (19.1%) and melanoma (7.1%). This 16-yr survey was divided equally into two time periods to compare the incidence of premalignant and malignant skin lesions at different time settings. Between 1991 and 1998, the incidence of cutaneous premalignancy was 0.10% which doubled during 1999-2006. For cutaneous malignancy, the incidence was 0.25% during 1991-1998 and 0.34% in 1999-2006. Incidence of AK among the new outpatients was 0.07% in 1991-1998 which staggered up to 0.15% in 1999-2006. These findings show an increase of both premalignant and malignant skin lesions, AK in particular in the dermatology outpatient-based incidence

    Nanomechanical Encoding Method Using Enhanced Thermal Concentration on a Metallic Nanobridge

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    We present a fast, energy-efficient nano-thermomechanical encoding scheme for digital information storage and retrieval. Digital encoding processes are conducted by the bistable electrothermal actuation of a scalable nanobridge device. The electrothermal energy is highly concentrated by enhanced electron/phonon scattering and heat insulation in a sub-100 nm metallic layer. The efficient conversion of electrothermal energy into mechanical strain allows digital switching and programming processes within 60 ns at 0.75 V with a programming energy of only 54 pJ. Furthermore, this encoding scheme together with the thermally robust design enables data retention at temperatures up to 400 °C. These results suggest that the proposed nano-thermomechanical encoding method could contribute to low-power electronics and robust information storage/retrieval systems

    A Pilot Study for the Neuroprotective Effect of Gongjin-dan on Transient Middle Cerebral Artery Occlusion-Induced Ischemic Rat Brain

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    In this study, we investigated whether gongjin-dan improves functional recovery and has neuroprotective effects on reducing the infarct volume after transient middle cerebral artery occlusion (MCAo). Infarct volume was measured using TTC staining and glucose utilization by F-18 FDG PET. Functional improvement was evaluated with the Rota-rod, treadmill, Garcia score test, and adhesive removal test. At 14 days after MCAo, neuronal cell survival, astrocytes expansion, and apoptosis were assessed by immunohistofluorescence staining in the peri-infarct region. Also, the expression of neurotrophic factors and inflammatory cytokines such as VEGF, BDNF, Cox-2, TNF-α, IL-1β, and IL-1α was measured in ischemic hemisphere regions. The gongjin-dan-treated group showed both reduced infarct volume and increased glucose utilization. Behavior tests demonstrated a significant improvement compared to the control. Also in the gongjin-dan treated group, NeuN-positive cells were increased and number of astrocytes, microglia, and apoptotic cells was significantly decreased compared with the control group in the ischemic peri-infarct area. Furthermore, the expression of VEGF and BDNF was increased and level of Cox-2, TNF-α, IL-1β, and IL-1α was decreased. These results suggest that gongjin-dan may improve functional outcome through the rapid restoration of metabolism and can be considered as a potential neuroprotective agent

    Impact of Depression on Work Productivity and Its Improvement after Outpatient Treatment with Antidepressants

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    AbstractObjectiveDepressive disorders influence socioeconomic burden at both the individual and organizational levels. This study estimates the lost productive time (LPT) and its resulting cost among workers with major depressive disorder (MDD) compared with a comparison group. It also estimates the change in productivity after 8 weeks of outpatient psychiatric treatment with antidepressants.MethodsWorking patients diagnosed with MDD without other major physical or mental disorders were recruited (n = 102), along with age- and sex-matched healthy controls from the Seoul Metropolitan area (n = 91). The World Health Organization's Health and Work Performance Questionnaire and the Hamilton Rating Scale for Depression were utilized to measure productivity and severity of depression, respectively, at baseline and at 8 weeks of treatment.ResultsThe LPT from absenteeism and presenteeism (reduced performance while present at work) was significantly higher among the MDD group. Workers with MDD averaged costs due to LPT at 33.4% of their average annual salary, whereas the comparison group averaged costs of 2.5% of annual salary. After 8 weeks of treatment, absenteeism and clinical symptoms of depression were significantly reduced and associated with significant improvement in self-rated job performance (31.8%) or cost savings of $7508 per employee per year.ConclusionsWe confirmed that significant productivity loss arises from MDD and that this loss can be reduced with psychiatric intervention after a time period as short as 8 weeks. Mental health professionals should work with employers to devise a cost-effective system to provide workers with accessible quality care
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