We report, for the first time to our knowledge, a novel and simple method for measuring continuous dispersion spectrum of unclamped linear electro-optic (EO) coefficient using a white-light ...interferometry. This method detects phase changes of the interference patterns with and without an applied electric voltage, and allows a simultaneous measurement of wavelength and polarization dependent EO coefficients of birefringent materials. Both of the unclamped EO coefficients, r(13) (T) and r(33) (T), of a congruent LiNbO(3) (LN) crystal have been measured simultaneously with the method, and their continuous dispersion curves have been also obtained.
Ketamine and dexmedetomidine are commonly used for sedation and analgesia in patients. We tried to compare the effects of intravenous ketamine and dexmedetomidine infusion on spinal block with ...bupivacaine.
Ninety American Society of Anesthesiologists physical status class I or II patients, who were scheduled to spinal anesthesia were randomly assigned to one of three groups (n = 30). Normal saline 10 ml, 5 ml/hr (loading dose for 10 minutes, infusion) (Group NS), dexmedetomidine 1 µg/kg, 0.5 µg/kg/hr (Group DEX), or ketamine 0.2 mg/kg, 0.5 mg/kg/hr (Group KET) was infused intravenously before spinal anesthesia. We recorded the time to highest sensory block level, sensory and motor regression, and hemodynamic changes.
Patients in Groups KET had a significantly faster onset time of sensory block than patients in Group NS. The highest sensory block levels were not significantly different between groups. Average time of sensory regression and knee flexion, was significantly longer in the Group KET and Group DEX than the Group NS.
Intravenous dexmedetomidine and ketamine were found to have a similar synergistic effect with intrathecal bupivacaine. Hemodynamic stability showed better results in Group KET.
The main disadvantage of rocuronium is the pain associated with vascular injection. We evaluated the efficacy of palonosetron for reducing pain after rocuronium injection.
EIGHTY PATIENTS SCHEDULED ...FOR ELECTIVE SURGERY WERE RANDOMLY DIVIDED INTO TWO GROUPS: Group C (normal saline 1.5 ml, n = 40) and Group P (palonosetron 0.075 mg, n = 40). Anesthesia was induced with thiopental 5 mg/kg and the test drug was injected over 10 seconds. Thirty seconds after the injection of the test drug, rocuronium 0.6 mg/kg was injected over 30 seconds and the response was recorded. Injection pain was graded using a 4-point scale. The grade was 0 points for no movement, 1 point for wrist movement, 2 points for elbow or shoulder movement, and 3 points for whole body movement. Mean arterial pressure and heart rate were recorded on arrival in the operating room and before and 30 seconds after rocuronim injection.
There was no significant difference in the grade 1 response between the two groups; however, the grade 2 and 3 responses in Group P were 5 (12.5%) and 4 (10%), respectively, which were significantly lower than in Group C, with 13 (32.5%) responses for each grade. There were no significant differences in hemodynamic changes within each group. However, the difference in mean arterial pressure before and after the injection of rocuronium was significantly larger in Group C compared to Group P.
Pretreatment with palonosetron 0.075 mg reduced the incidence and severity of withdrawal movement after rocuronium administration.
We report the effect of an external injection laser wavelength on reducing the timing jitter of optical pulses generated from gain-switched single-mode 1.5-μm vertical cavity surface emitting lasers ...(VCSELs). Simultaneous timing jitter reduction, pulse width shortening, and spectral linewidth narrowing without any peak power penalty were observed when the injection laser wavelength was tuned near the spectral peak of the free-running VCSELs spectrum operating in a continuous wave mode. The timing jitter was reduced up to 40% of that without any injection.
We report the first experimental invetigation of the polarization-mode switching dynamics and injection- wavelength-dependent polarization-mode bistability of a 1.5-m wavelength single-mode ...vertical-cavity surface-emitting lasers (VCSELs) under external laser beam injection. An injection beam with polarization orthogonal to that of the stand-alone VCSEL caused polarization-mode instability and switching of the VCSEL output. By varying the optical injection detuning for fixed injection power observation was made of a novel form of polarization bistability which will have applications in a new type of all-optical flip-flop and signal processing scheme.
We review the temporal dynamics of the laser output spectrum and polarization state of 1.55 μm wavelength single-mode (SM) vertical-cavity surface-emitting lasers (VCSELs) induced by external optical ...beam injection. Injection of an external continuous-wave laser beam to a gain-switched SM VCSEL near the resonance wavelength corresponding to its main polarization-mode output was critical for improvement of its laser pulse generation characteristics, such as pulse timing-jitter reduction, linewidth narrowing, pulse amplitude enhancement, and pulse width shortening. Pulse injection of pulse width shorter than the cavity photon lifetime into the SM VCSEL in the orthogonal polarization direction with respect to its main polarization mode caused temporal delay of the polarization recovery after polarization switching (PS), and its delay was found to be the minimum at an optimized bias current. Polarization-mode bistability was observed even in the laser output of an SM VCSEL of a standard circularly cylindrical shape and used for all-optical flip-flop operations with set and reset injection pulses of very low pulse energy of order of the 3.5~4.5 fJ.
Abstract
Phase transition in nanomaterials is distinct from that in 3D bulk materials owing to the dominant contribution of surface energy. Among nanomaterials, 2D materials have shown unique phase ...transition behaviors due to their larger surface‐to‐volume ratio, high crystallinity, and lack of dangling bonds in atomically thin layers. Here, the anomalous dimensionality‐driven phase transition of molybdenum ditelluride (MoTe
2
) encapsulated by hexagonal boron nitride (hBN) is reported. After encapsulation annealing, single‐crystal 2H‐MoTe
2
transformed into polycrystalline T
d
‐MoTe
2
with tilt‐angle grain boundaries of 60°‐glide‐reflection and 120°‐twofold rotation. In contrast to conventional nanomaterials, the hBN‐encapsulated MoTe
2
exhibit a deterministic dependence of the phase transition on the number of layers, in which the thinner MoTe
2
has a higher 2H‐to‐T
d
phase transition temperature. In addition, the vertical and lateral phase transitions of the stacked MoTe
2
with different crystalline orientations can be controlled by inserted graphene layers and the thickness of the heterostructure. Finally, it is shown that seamless T
d
contacts for 2H‐MoTe
2
transistors can be fabricated by using the dimensionality‐driven phase transition. The work provides insight into the phase transition of 2D materials and van der Waals heterostructures and illustrates a novel method for the fabrication of multi‐phase 2D electronics.
We report a simple method of measuring the absolute values of the phase refractive index of an optical material of a flat plate shape over a wide spectral range at a single measurement run. A ...white-light interferometric technique with angle rotation of the optical plate sample located in one of the interferometer arms was used in this method. The validity of this method was proved by measuring the absolute phase refractive indices of flat plate samples of fused silica and BK7, and by comparing them with calculated values from their well-known Sellmeier dispersion formulas. The accuracy of this refractive index measurement method was within 0.002, which can be further improved by enhancing the angle measurement accuracy of the angle rotating stage used in this method.
본 연구에서는 국가에서 제공하는 일반엑스선검사의 진단참고수준 중 다빈도 검사에 대한 유효선량을 몬테카를로 시뮬레이션을 이용하여 평가하고자 하였다. 일반엑스선검사의 진단참고수준에 대한 유효선량 평가는 가장 다빈도로 검사되는 두부 전후면(Anterior-Posterior; AP), 흉부 후전면(Posterior-Anterior; PA), 흉부 ...측면(Lateral; LAT), 복부 AP, 골반 AP 등 총 5개의 검사 부위로 선정하였다. 몬테카를로 시뮬레이션에 사용되는 관전압과 관전류 등의 물리적 조건은 국내 조건의 대표성을 나타내기 위해 질병관리청의 자료를 사용하였다. 국내 의료방사선 피폭량 평가를 위해 사용된 인체 전산 팬텀은 한국인의 표준 체형을 대표할 수 있고 국제규격의 ICRP 103 기반으로 제작된 HDRK-Man 전산 인체팬텀을 몬테카를로 시뮬레이션에 적용하였다. 그 결과, 성인 남성을 기준으로 두부 AP의 진단참고수준에 해당되는 유효선량은 0.086 mSv, 흉부 PA는 0.05 mSv, 흉부 LAT는 0.354 mSv, 복부 AP는 0.548 mSv, 골반 AP는 0.451 mSv로 평가되었다.
In this study, the effective dose for frequently general radiography among the diagnostic reference level (DRL) for examinations provided by the government in Korea was evaluated using the Monte Carlo N-Particle eXtended (MCNPX) simulation tool. We were selected to evaluate for a total of 5 examination sites which included head anterior-posterior, chest (posterior-anterior, lateral), abdomen anterior-posterior and pelvis anterior-posterior. Physical conditions such as tube voltage and tube current used in MCNPX simulation were used in domestic conditions of the Korea Disease Control and Prevention Agency (KDCA). To evaluate domestic medical radiation exposure, we used the HDRK-Man computerized human phantom manufactured based on the international standard ICRP 103 that was applied to the MCNPX simulation. The phantom could represent the standard body shape of Koreans. As a results, the effective dose corresponding to the DRL based on adult males of head anterior-posterior position was 0.086 mSv, chest posterior-anterior position was 0.05 mSv, chest lateral was 0.354 mSv, abdomen anterior-posterior position was 0.548 mSv, and pelvis anterior-posterior position was 0.451 mSv.
We demonstrate improved single photon detection efficiencies of InGaAs/InP avalanche photodiodes (APDs) in a wavelength-division-multiplexed (WDM) scheme for high-capacity plug-and-play-type two-way ...quantum key distributions (QKDs). Single-photon detectors (SPDs) combined in the WDM APD scheme can be used to overcome the detection speed limit of a single SPD which is caused mainly by the afterpulse effect. The multiple SPDs combined in the parallel WDM scheme can increase the single photon detection capacity, although additional optical losses resulted from the WDM MUX and deMUX devices induce limited increases.
•Multiple InGaAs/InP APDs in a WDM scheme overcomes the detection speed limit caused by afterpulsing.•Demonstration of a proof of principle for the WDM SPDs scheme.
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