Dynamics of surface-plasmon lasing in planar metal gratings on semiconductor.

We investigate the dynamics of surface plasmon (SP) lasing in Au gratings fabricated on InGaAs with a period of around 400 nm, which locates the SP resonance near the semiconductor energy gap and facilitates efficient energy transfer. By optically pumping the InGaAs to reach the population inversion required for the amplification and the lasing, we observe SP lasing at specific wavelengths that satisfy the SPR condition depending on the grating period. The carrier dynamics in semiconductor and the photon density in the SP cavity was investigated from the time-resolved pump-probe measurement and the time resolved photoluminescence spectroscopy, respectively. Our results reveal that the photon dynamics is strongly correlated with the carrier dynamics and the lasing build-up is accelerated as the initial gain proportional to the pumping power increases, and this trend is satisfactorily explained using the rate equation model.

Effects of High-Temperature Growth of Dislocation Filter Layers in GaAs-on-Si.

GaAs-on-Si templates with two different dislocation filter layers (DFLs) were grown at 550 °C low-temperature (LT)-DFL and 660 °C high-temperature (HT)-DFL using metal organic vapor-phase epitaxy and the effects of the growth temperature were studied. The threading dislocation density (TDD) values of LT-DFL and HT-DFL were 5.2 × 107 cm-2 and 1.5 × 107 cm-2, respectively. The 1.5 × 107 cm-2 of TDD in HT-DFL is reduced by almost one order compared to the 1.2 × 108 cm-2 of that in the control sample without DFLs. The annihilation process was mainly observed in the HT-DFL by a transmission electron microscope, resulting in a lower TDD. The 500-nm-thick GaAs bulk layer and InAs QDs were regrown on GaAs-on-Si templates and the optical properties were also evaluated by photoluminescence (PL). The highest PL peak intensity of the HT-DFL indicates that less non-radiative recombination in both the GaAs bulk and QDs occurred due to the reduced TDD. The GaAs p-i-n diodes were also fabricated to analyze the bulk leakage (JB) and the surface leakage current. The JB of HT-DFL shows the lowest value of 3.625 × 10-7 A/cm-2 at applied bias voltage of 1 V, which is 20 times lower than the JB of the control sample without DFLs. This supports that the high-temperature growth of DFL can make a good performance GaAs device on Si.

Comparison between self-reported smoking habits and daily ad-libitum smoking topography in a group of Korean smokers.

Tobacco smoking is associated with a high global mortality rate since it is known to cause cancers and lung and heart diseases. To control and reduce annual mortality attributed to smoking, it is essential to design applicable smoke cessation programs based on realistic tobacco exposure risk assessment. In this regard, understanding the smoking habits of the smoker is crucial. Using self-report smoking habit surveys is a common approach in measuring basic variables of smoking habits. However, smoking topography measurement devices have recently become available for investigating smoking habit variables accurately. In this study, we conducted a self-report survey to investigate a group of Korean smokers' smoking habit variables such as the number of smoked cigarettes per day, puff counts, and total smoking time. The survey also included items from the Fagerström Test for Nicotine Dependence (FTND). The results were compared with the corresponding variables from machine-determined data to investigate their correlation and reliability. Results indicate that Korean smokers have a reliable understanding of the average number of cigarettes they smoke daily (ρ = 0.517, Cronbach's α = 0.754) and the time to first cigarette (TTFC) after waking up (ρ = -0.587, Cronbach's α = 0.623), as fundamental items of the FTND score. Nevertheless, these smokers significantly under-reported the puff number and total smoking time, which can cause significant underestimation in the tobacco exposure risk assessment. Consequently, we suggest the application of self-report surveys that are based on the amount of daily smoked cigarettes (e.g. FTND) for clinical or risk assessment purposes. Using smoking topography measurement devices is recommended overusing self-report surveys in measuring smoking habit variables such as puff count and smoking time more accurately.

Exposure and Risk Assessment of Second- and Third-Hand Tobacco Smoke Using Urinary Cotinine Levels in South Korea.

Exposure to environmental tobacco smoke (ETS) is the reason for approximately 1% of global mortality. ETS exposure can happen either as inhalation of direct cigarette smoke (second-hand smoke) or its associated residue particles (third-hand smoke), especially when living with a smoker in the same family. This study investigated the association between the urinary cotinine levels, as biomarkers of exposure to tobacco smoke, of smokers and those exposed to second-hand and third-hand smoke while living in the same family, through a Korean nationwide survey. Direct assessment of ETS exposure and its lifetime effect on human health is practically difficult. Therefore, this study evaluated the internal estimated daily intake (I-EDI) of nicotine and equivalent smoked cigarette per day (CPD). The carcinogenic and non-carcinogenic inhalation risks of ETS exposure were assessed by considering the calculated equivalent CPD and composition of cigarette smoke of high-selling cigarette brands in South Korea. The results show that there is a statistically significant positive correlation between the cotinine levels of smokers and those of the non-smokers living in the same family. The risk assessment results yielded that hazard index (HI) and total excess lifetime cancer risk (ECR) for both second-hand and third-hand smoke exposure can exceed 1 and 1 × 10-6, respectively, especially in women and children. In the composition of the cigarette smoke, 1,3-butadiene and acrolein substances had the highest contribution to HI and ECR. Consequently, the provision of appropriate plans for smoking cessation as a strategy for the prevention of ETS exposure to women and children is deemed necessary.

Study on the daily Ad Libitum smoking habits of active Korean smokers and their effect on urinary smoking exposure and impact biomarkers.

INTRODUCTION: Understanding interactions of smoking topography with biomarkers of exposure to tobacco is essential for accurate smoking risk assessments. METHODS: In this study, the smoking topography and the levels of tobacco smoke exposure urinary biomarkers of a sample of active Korean smokers were quantified and measured. The results were used to investigate the effect of daily activities and smoking time on the smoking topography. Moreover, correlations between the smoking topography parameters and biomarkers were assessed. RESULTS: No significant effect of either the daily activities or time on the smoking topography of the subjects were observed. Synchronic correlations of the cigarette consumption per day (CPD) and the average flow per puff with both urinary cotinine and trans-3'-hydroxycotinine were significant. For the urinary nicotine metabolites, the peak levels appeared when the CPD was over 19 cigarettes per day and the average puff velocity was between 35 and 45 ml/s. Nevertheless, when the average flow was over 60 ml/s, the levels of cotinine and trans-3'-hydroxycotinine significantly dropped. CONCLUSIONS: The findings of this study may be beneficial for further smoking risk assessments with contributions of both the smoking topography and biomarkers to provide current smokers with applicable cession programs.Clinical significanceSmoking habits and levels of urinary biomarkers of Korean smokers are investigated.People with a higher dependency on nicotine smoke cigarettes with slower puffs.Effects of daily activities or time on smoking topography were not significant.Correlations between smoking topography and urinary biomarkers were significant.Peak biomarker levels were observed under certain smoking topography conditions.

Korean male active smokers: quantifying their smoking habits and the transformation factor among biomarkers in urine and blood.

OBJECTIVES: The aim of the study was to investigate the correlations within the levels of biomarkers in different biological matrices, along with smoking topography variables, among active male smokers in Korea. Accordingly, we defined a transformation factor to convert level of tobacco smoke exposure and impact biomarkers from different biometrics. METHODS: We examined smoking topography of recruited volunteers using a self-reporting survey. The level of tobacco smoke exposure and impact biomarkers in subjects' urine and blood were analysed. Results were used to assess the correlations between the topography survey items with biomarkers in biological matrices. The relationship between the biomarkers in urine and blood was analysed. Accordingly, we defined a transformation factor as the ratio of different biomarkers in urine and blood matrices. RESULTS: Significant correlations among smoking topography variables and biomarkers were found. Besides, a strong significant association was found among urine and blood cotinine (ρ = 0.817) and NMR (ρ = 0.905). Urine vs blood cotinine and NMR transformation factors were calculated to be 6.17 L-Blood/g-Creatinine and 10.2, respectively. CONCLUSIONS: The validated transformation factor connects epidemiological cohort studies with tobacco smoking exposure risk assessment. Hence, this study might be beneficial for further habit-based smoking risk assessments to obtain successful regional cession policies.

Strong optical modulation of surface plasmon polaritons in metal/semiconductor nanostructures.

We demonstrate strong modulation of the transmission around the surface plasmon polariton (SPP) resonance in metal/semiconductor hybrid nanostructures based on Ag film on top of InGaAs. The change in the real and imaginary parts of the refractive index due to photoexcited carriers in InGaAs generates a shift in the SPP resonance and enhanced transmission near the SPP resonance. Temporal evolution of the complex refractive index was traced by comparing the transient transmission with finite-difference time-domain (FDTD) simulations.

Alternative method for creating fine hairs with hair removal laser in hair transplantation for hairline correction.

BACKGROUND: Foremost fine hairs in the frontal hairline region are critical in hair transplantation for hairline correction (HTHC) in women. However, there are few studies on a nonsurgical revisionary method for improving an unnatural foremost hairline with thick donor hairs resulting from a previous HTHC. OBJECTIVE: To investigate the efficacy and safety of using a hair removal laser (HRL) system to create fine hairs in Asian women with thick donor hairs. METHODS: Through a retrospective chart review, the HRL parameters, hair diameter (measured with a micrometer before and after the procedures), subjective results after the procedures, adverse effects, and the number of procedures were investigated. The reduction rate of the hair diameter was calculated. RESULTS: Twenty-four women who received long-pulse Neodymium-Doped:Yttrium Aluminum Garnet therapy after HTHC were included. The parameters were as follows: delivered laser energy, 35~36 J/cm(2); pulse duration, 6 ms; and spot size, 10 mm. The mean number of laser sessions was 2.6. The mean hair diameter significantly decreased from 80.0±11.5 µm to 58.4±13.2 µm (p=0.00). The mean rate of hair diameter reduction was -25.7% (range, -44.6% to 5.7%). The number of laser sessions and the hair diameter after the procedures showed a negative correlation (r=-0.410, p=0.046). Most of the patients (87.5%) reported subjective improvement of their hairlines. Most complications were transient and mild. CONCLUSION: HRL can be an alternative method for creating fine hairs and revising foremost hairline in Asian women with thick donor hairs.

Optimization of spot-size converter for low polarization dependent loss of waveguide photodetector.

We present an optimization of spot-size converter (SSC) of waveguide photodetector (PD) for small polarization dependent loss (PDL). Beam-propagation method simulation gives responsivity for each polarization and SSC structure. From the calculated responsivity data, optimum structure of SSC is determined that can be implemented with a sufficient process tolerance. We confirm the optimization by measuring PDL of waveguide PD designed according to the structure obtained through the simulation.

Staphylococcus aureus pericardial abscess presenting as severe sepsis and septic shock after acupuncture therapy.

Pericardial abscess is an extremely rare complication of Staphylococcus aureus bacteremia. We report a case of a 72-year-old woman with multiple acupuncture scars on both knees who presented with shortness of breath and general weakness. Transthoracic echocardiography and pericardiocentesis confirmed the presence of pericardial fluid collection. Staphylococcus aureus grew in both pericardial fluid and blood. Although an aggressive medical treatment including intravenous antibiotics and percutaneous drainage, the patient died 2 days after admission.

Successful treatment of an iatrogenic giant femoral artery pseudoaneurysm with percutaneous thrombin injection.

A femoral artery pseudoaneurysm (FAP) is one of the most troublesome complications following invasive procedures related to the femoral arterial access. Post-procedure FAP rarely occurs; however, its occurrence tends to increase with the more frequently antiplatelet agents, anticoagulants, and larger-sized catheter used for interventional procedures. Traditionally, surgical repair has been considered as the standard treatment modality for FAP; however, less invasive methods currently exist such as blind manual or ultrasound-guided compression repair (UGCR) as well as percutaneous thrombin injection, both of which have replaced the need for surgery. We report a case of a giant pseudoaneurysm in a femoral artery, which had developed as a complication of stenting in a patient with carotid artery stenosis and ischemic heart disease, and was subsequently successfully treated using percutaneous thrombin injection.