52 research outputs found

    Tunable all-dielectric metasurface for phase modulation of the reflected and transmitted light via permittivity tuning of indium tin oxide

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    We propose an electrically tunable metasurface, which can achieve relatively large phase modulation in both reflection and transmission modes (dual-mode operation). By integration of an ultrathin layer of indium tin oxide (ITO) as an electro-optically tunable material into a semiconductor-insulator-semiconductor (SIS) unit cell, we report an approach for active tuning of all-dielectric metasurfaces. The proposed controllable dual-mode metasurface includes an array of silicon (Si) nanodisks connected together via Si nanobars. These are placed on top of alumina and ITO layers, followed by a Si slab and a silica substrate. The required optical resonances are separately excited by Si nanobars in reflection and Si nanodisks in transmission, enabling highly confined electromagnetic fields at the ITO-alumina interface. Modulation of charge carrier concentration and refractive index in the ITO accumulation layer by varying the applied bias voltage leads to 240° of phase agility at an operating wavelength of 1696 nm for the reflected transverse electric (TE)-polarized beam and 270° of phase shift at 1563 nm for the transmitted transverse magnetic (TM)-polarized light. Independent and isolated control of the reflection and transmission modes enables distinctly different functions to be achieved for each operation mode. A rigorous coupled electrical and optical model is employed to characterize the carrier distributions in ITO and Si under applied bias and to accurately assess the voltage-dependent effects of inhomogeneous carrier profiles on the optical behavior of a unit cell

    Tunable all-dielectric metasurface for phase modulation of the reflected and transmitted light via permittivity tuning of indium tin oxide

    Get PDF
    We propose an electrically tunable metasurface, which can achieve relatively large phase modulation in both reflection and transmission modes (dual-mode operation). By integration of an ultrathin layer of indium tin oxide (ITO) as an electro-optically tunable material into a semiconductor-insulator-semiconductor (SIS) unit cell, we report an approach for active tuning of all-dielectric metasurfaces. The proposed controllable dual-mode metasurface includes an array of silicon (Si) nanodisks connected together via Si nanobars. These are placed on top of alumina and ITO layers, followed by a Si slab and a silica substrate. The required optical resonances are separately excited by Si nanobars in reflection and Si nanodisks in transmission, enabling highly confined electromagnetic fields at the ITO-alumina interface. Modulation of charge carrier concentration and refractive index in the ITO accumulation layer by varying the applied bias voltage leads to 240° of phase agility at an operating wavelength of 1696 nm for the reflected transverse electric (TE)-polarized beam and 270° of phase shift at 1563 nm for the transmitted transverse magnetic (TM)-polarized light. Independent and isolated control of the reflection and transmission modes enables distinctly different functions to be achieved for each operation mode. A rigorous coupled electrical and optical model is employed to characterize the carrier distributions in ITO and Si under applied bias and to accurately assess the voltage-dependent effects of inhomogeneous carrier profiles on the optical behavior of a unit cell

    Lump-Sum Bonus Satisfaction: Testing the Construct Validity of a New Pay Satisfaction Dimension

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    There are both practical and theoretical reasons to measure lump-sum bonus satisfaction. The practical need for such a measure stems from its increased use as a component in modern compensation practices. Based on the means of administering and allocating lump-sum bonuses, a theoretical case can be built suggesting that lump-sum bonus satisfaction constitutes a separate component of pay satisfaction fitting into the Pay Satisfaction Questionaire\u27s (PSQ) theoretical framework. We develop 4 questions that complement the PSQ, and use a series of techniques to test the convergent and discriminant validity of the measure. Empirical evidence shows that bonus-related items are more related to the lump-sum bonus satisfaction measure than other PSQ dimensions. We also demonstrate that the dimension of lump-sum bonus satisfaction has a substantive relationship with attitudinal variables beyond that provided by pay level variables and the PSQ. The development of this measure should foster greater accuracy when assessing pay satisfaction levels and the effects of lump-sum bonus pay policies

    A New Theorem Concerning Scattering of Electromagnetic Waves in Multilayered Metamaterial Spherical Structures

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    The proposed theorem in this paper is indicative of a kind of duality in the propagation of waves in the dual media of and in the spherical structures. Independent of wave frequency, the number of layers, their thickness, and the type of polarization, this theorem holds true in case of any change in any of these conditions. Theorem: Consider a plane wave incident on a multilayered spherical structure. The core of structure may be PEC, metamaterial or dielectric. If we apply the interchange or for the constituting materials of the spherical structure and the surrounding medium the radar cross section of the structure will not change in any direction

    Comparison of Preanesthetic Sedation after Intranasal Administration of Fentanyle, Ketamin and Midazolam

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    Introduction & Objective: Induction of anesthesia in children can be a challenge for anesthetist. A stormy induction may increase the personality & behavioral changes. Therefore, it is desirable that they enter the operating room sedated. Many drugs are used for preanesthetic medication and there are many routes for administration. One route of administration is nasal mucous. In this study we compared the effect and side effect of three drugs (midazolam, ketamin and fentanyle) after intra nasal administration. Materials & Methods: This is a double blind clinical trial. In this study we selected 60 patients (20 patients for every group A, B or C.) We used 3 mg/kg ketamin or 3µg/kg fentanyle or 0.3 mg/kg midazolam by intranasal spray. After administration and in 5, 10 and 15 minutes, we observed the SPO2, PR and RR. After 15 min’s we separated children from parents and brought them to the operating room and controlled the acceptance of separation, depth of sedation with Ramsay score, acceptance of mask and tolerance of IV canulation. The data were then analyzed using K2 and kruskal-wallis test. Results: In our study we found that in SPO2 fentanyle had the highest rate of reduction even though none of the children had SPO2 lower than 90%. There were no differences between drugs in RR. In fentanyle group, we had the lowest rate and in ketamin group the highest rate. Midazolam had the medium rate. The rate of sedation for acceptance of separation from parents had no difference between the groups and all drugs with this dosage were effective for this aim. However, in Ramsay score, acceptance of mask and tolerance of IV canulation, the midazolam was more effective than the others. Conclusion: Intranasal administration of midazolam is a safe route for sedation in children in the pre-anesthetic time

    Evaluation of high dose atorvastatin therapy 24 hours before elective percutaneous coronary intervention on peri-PCI myocardial infarction

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    Background: Percutaneous coronary intervention (PCI) may been associated with high-er risk of cardiac events during this procedure. The goal of this study was to compare high dose atorvastatin therapy with low dose atorvastatin therapy 24 hours before PCI to a reduction in Peri- percutaneous coronary intervention myocardial infarction.Methods: One hundred ninety patients with stable angina were enrolled in a randomiz-ed controlled clinical trial study. All patients received low dose atorvastatin. The patients scheduled for elective PCI were randomized to atorvastatin (80 mg/d, n=95) or placebo (n=95) within 24 hours before the procedure. Creatine kinase-MB, troponin I, and high sensitive C- reactive protein levels were measured at baseline and at 6 and 12 hours after the procedure. PCI related myocardial infarction was defined as increasing of Creatine kinase-MB or troponin I three times compared with values before procedure.Results: Myocardial infarction was detected after coronary intervention in 4.2% of patients in the atorvastatin group and in 13.7% of those in the placebo group (P=0.022). Mean of changed levels of Creatine kinase-MB (0.7&plusmn;0.5 versus 3.3&plusmn;1.9 ng/mL, P<0.001), troponin I (0.1&plusmn;0.2 versus 0.4&plusmn;0.7 ng/mL, P=0.052) and hs-CRP (0.1&plusmn;0.5 versus 1&plusmn;0.9 ng/mL, P<0.001) were significantly lower in the statin than in the placebo group.Conclusion: Pretreatment with high dose atorvastatin within 24 hours before elective percutaneous coronary intervention significantly reduces procedural myocardial infarct-tion in elective coronary intervention

    Effect of Two Different Levels of Fiber on Feed Intake, Average Daily Gain, Feed Efficiency and Ruminal Metabolites of Holstein Calves

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    This experiment was conducted to determine the effect of feeding alfalfa hay and starter fiber level on feed intake and performance of Holstein dairy calves, using thirty two male calves in a completely randomized design assigned to four diets in a 2×2 factorial arrangement. The experimental treatments were as follow: T1: starter with low fiber and without alfalfa hay, T2: starter with low fiber along with alfalfa hay, T3: starter with high fiber and without alfalfa hay and T4: starter with high fiber along with alfalfa hay. Results showed feed intake was not significantly different in pre-weaning and throughout the study but after weaning there was significant difference among treatments. Average daily gain of calves was not significantly different during pre-weaning period but during post-weaning and throughout the study there was significant difference among treatments for this trait. Feed efficiency was not significantly different among treatments in pre-weaning and post-weaning periods but it was significantly different during throughout the study. The results of this experiment showed adding fiber to dairy calves ration through both starter concentrate and alfalfa hay may reduce their performance
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