Hybrid Slot Research Articles

Inverse dispersion engineering in silicon waveguides

We present a numerical tool that searches an optimal cross section geometry of silicon-on-insulator waveguides given a target dispersion profile. The approach is a gradient-based multidimensional method whose efficiency resides on the simultaneous calculation of the propagation constant derivatives with respect to all geometrical parameters of the structure by using the waveguide mode distribution. The algorithm is compatible with regular mode solvers. As an illustrative example, using a silicon slot hybrid waveguide with 4 independent degrees of freedom, our approach finds ultra-flattened (either normal or anomalous) dispersion over 350 nm bandwidth in less than 10 iterations.

Extreme light confinement and low loss in triangle hybrid plasmonic waveguide

A low-loss triangle hybrid plasmonic waveguide to confine light at an ultra-deep subwavelength scale is proposed and numerically investigated. Compared to other hybrid slot plasmonic waveguides based on cylinder or square semiconductor nanowires, the novel hybrid plasmonic waveguide based on triangle semiconductor nanowire has not only stronger field confinement, but also lower propagation loss. Detailed study of this structure reveals that these advantages originate from the tip enhancement of the triangle semiconductor waveguide. This mechanism of the waveguide permits tolerance for structural imperfection in actual experiments, which is very feasible for experimental realization. The extreme confinement of light can lead to strong electric field around the tip of the triangle semiconductor waveguide, thus can greatly enhance the light-matter interaction. Various applications will benefit from this triangle hybrid plasmonic waveguide, such as the laser, waveguide (cavity) quantum electrodynamics and optomechanics.

Polymer-Based Hybrid-Integrated Photonic Devices for Silicon On-Chip Modulation and Board-Level Optical Interconnects

The accelerating increase in information traffic demands the expansion of optical access network systems that require the cost reduction of optical and photonic components. Low cost, ease of fabrication, and integration capabilities of low optical-loss polymers make them attractive for photonic applications. In addition to passive wave-guiding components, electro-optic (EO) polymers consisting of a polymeric matrix doped with organic nonlinear chromophores have enabled wide-RF-bandwidth and low-power optical modulators. Beside board level passive and active optical components, compact on-chip modulators (a few 100 μm to a few millimeters) have been made possible by hybrid integration of EO polymers onto the silicon platform. This paper summarizes some of the recent progress in polymer-based optical modulators and interconnects. A highly linear, broadband directional coupler modulator for use in analog optical links and compact, and low-power silicon/polymer hybrid slot photonic crystal waveguide modulators for on chip applications are presented. Recently, cost-effective roll-to-roll fabrication of electronic and photonic systems on flexible substrates has been gaining interest. A low-cost imprinted/ink-jet-printed Mach–Zehnder modulator and board-to-board optical interconnects using microlens integrated 45° mirror couplers compatible with the roll-to-roll fabrication platforms are also presented.

A Novel Hybrid Slot Allocation Mechanism for 802.11e EDCA Protocol

This letter proposes a novel Hybrid Slot Allocation Mechanism (HSAM) to solve the high collision problem among four Access Categories (ACs) introduced by IEEE 802.11e EDCA protocol. In the HSAM, three time slots are assembled into a super-slot, each slot in the super slot is allocated to a particular AC according to its priority. The main idea of HSAM is to stagger the transmission slots of different ACs to reduce collisions, while maintaining the service differentiation. Extensive results from simulations have demonstrated good performance of HSAM comparing with EDCA protocol in terms of throughput, packet loss and MAC delay.

Low-loss light transport at the subwavelength scale in silicon nano-slot based symmetric hybrid plasmonic waveguiding schemes

A hybrid plasmonic structure comprising a silicon slot waveguide separated from an inverse metal ridge by a thin low-index insulator gap is proposed and investigated. Owing to its symmetric hybrid configuration containing closely spaced silicon rails near the metal ridge, the fundamental symmetric hybrid slot mode supported by the structure is demonstrated to be capable of simultaneously achieving low propagation loss and subwavelength field confinement within a wide range of physical dimensions at the telecom wavelength. Comprehensive numerical investigations regarding the effects of key geometric parameters on the guided modes' properties, including the slot sizes, the shape and dimension of the silicon rails, the width of the gap region as well as the height of metallic nanoridge, have been conducted. It is revealed that the propagation distance of the symmetric mode can be more than several millimeters (even up to the centimeter range), while simultaneously achieving a subwavelength mode size and tight field confinement inside the gap region. In addition to the studies on the modal characteristics, excitation strategies of the guided hybrid modes and the conversion between dielectric slot and hybrid slot modes are also numerically demonstrated. The studied platform potentially combines the advantages of silicon slot and plasmonic structures, which might lay important groundwork for future hybrid integrated photonic components and circuits.

A JTIDS/INS/DGPS navigation system with pseudorange differential information transmitted over Link-16: design and implementation

As the battle environment becomes more complicated, the demand for higher accuracy and better anti-jam capacity of navigation has been increasing. The conventional JTIDS/INS/GPS integrated navigation cannot meet the demands of certain situations such as precision strike and formation flight. A new system that introduces the differential GPS into JTIDS/INS/GPS integration system is proposed to improve the navigation performance in the modern combined operations. In this system, the differential information of DGPS is transmitted through the communication data link of Link-16. As a result, the system resources are efficiently utilized and the controllability and anti-jam performance of the system are significantly enhanced. A hybrid slot allocation protocol (HSAP) that combines a static slot allocation algorithm and a dynamic slot allocation algorithm and the corresponding source-chosen mechanisms are proposed. The performance of the JTIDS/INS/GPS integration navigation using the differential GPS information from one or multiple base stations is studied and compared with that of the system without using the differential GPS information. Furthermore, the performance of the integration navigation using HSAP is compared with that of the system using static slot allocation algorithm. We show that navigation accuracy based on the differential GPS is improved, and using HSAP also leads to higher localization accuracy.

High‐Optical‐Quality Blends of Anionic Polymethine Salts and Polycarbonate with Enhanced Third‐Order Non‐linearities for Silicon‐Organic Hybrid Devices

A series of anionic polymethine dyes with different aromatic counterions are prepared to improve their compatibility as guests in an amorphous polycarbonate host. When they are used as the cladding material for silicon hybrid slot waveguides, four-wave mixing wavelength conversion and two-photon absorption-based optical-power modulation are observed. Such guest-host materials may be attractive candidates for all-optical signal-processing applications.

Investigation of Torque–Speed Characteristics and Cogging Torque of Fractional-Slot IPM Brushless AC Machines Having Alternate Slot Openings

This paper presents a comparative study of torque-speed characteristics and cogging torque of the fractional-slot interior permanent magnet brushless ac machines having different slot openings, viz. open slot, closed slot, and hybrid slot (sandwiched open and closed slots), and unskewed and step skewed rotors. The influence of such alternate slot openings on the magnetic cross-coupling and cogging torque is particularly emphasized. Furthermore, the repercussion of the manufacturing limitations and tolerances on the cogging torque of machines having these alternate slot openings is also investigated. The magnetic cross-coupling level and the sensitivity of cogging torque to manufacturing limitations and tolerances strongly depend on the slot opening materials. The finite-element analyses are experimentally validated.

Design of Compact Dual-Polarized Antennas for MIMO Handsets

A design method of compact dual-polarized antennas has been proposed for multiple input and multiple output (MIMO) handset application. For the sake of high isolation in dual polarizations, a printed monopole and a hybrid slot antenna are combined using a coplanar waveguide (CPW) and microstrip hybrid feeding structure. The proposed topology will result in orthogonal current distribution modes for the different polarizations, which effectively reduces the mutual coupling of the two modes. The operation mechanism of the feeding structure is analyzed in principle and verified by simulation. Simulated and measured results show this compact dual-polarized antenna achieves isolation between the two ports of better than 25 dB, and the relative bandwidth is wider than 23.5%.

Slot 코팅 공정에서 Non-Newtonian 유체의 코팅 균일성을 위한 최적 다이 설계

본 연구에서는 전산유체모사기인 Fluent를 활용하여 slot 다이 내부에서 Newtonian과 non-Newtonian 코팅액의 동적 거동을 고찰함으로써 최적 다이 설계를 위한 방법론을 구축하고자 하였다. 다이 출구에서 코팅액의 속도분포를 일정하게 하기 위해 chamber 구조를 변화시킴으로써 최적 하이브리드 다이의 설계가 가능하였다. 특히, non-Newtonian 유체의 경우, 전단담화 정도와 chamber의 coat-hanger 최적 길이의 상관관계를 도출하였다. In this study, the flow behavior of Newtonian and non-Newtonian coating liquids inside slot die has been scrutinized for the purpose of optimal internal die design in slot coating system from three-dimensional computations by CFD Fluent solver. A hybrid slot die could be optimally designed by changing the chamber or manifold structure to guarantee the uniform velocity distribution of coating liquids at die exit. Especially, for the non-Newtonian coating liquids, the length of coat-hanger for the uniform coating has been properly chosen, according to the degree of their shearthinning properties.

Silicon-polymer hybrid slot waveguide ring-resonator modulator

We demonstrate a ring-resonator modulator based on a silicon-polymer hybrid slot waveguide with a tunability of 12.7 pm/V at RF speeds and a bandwidth of 1 GHz, for optical wavelengths near 1550 nm. Our slot waveguides were fabricated with 193 nm optical lithography, as opposed to the electron beam lithography used for previous results. The tunability is comparable to some of the best ring-based modulators making use of the plasma dispersion effect. The speed is likely limited only by resistance in the strip-loading section, and it should be possible to realize significant improvement with improved processing.

Gene Expression and Identification Related to Fluconazole Resistance of Candida glabrata Strains

ObjectivesCandida glabrata has become one of the most common causes of Candida bloodstream infections worldwide. Some strains of C. glabrata may be intermediately resistant to all azoles. The several possible mechanisms of azole resistance have been reported previously, but the exact resistant mechanism is not clear. In this study, we identified differentially expressed genes (DEGs) of fluconazole-resistant C. glabrata and compared the gene expression of fluconazole-resistant strains with that of fluconazole-susceptible strains to identify gene corresponding to fluconazole resistance. MethodsUsing antifungal susceptibility test, several C. glabrata strains were selected and used for further study. The expression of CgCDR1 and CgCDR2 genes was investigated by slot hybridization against fluconazole-susceptible, -resistant, and resistant-induced strains. In addition, ERG3 and ERG11 genes were sequenced to analyze DNA base substitution. DEGs were identified by reverse transcription-polymerase chain reaction using DEG kit composed of 120 random primers. ResultsIn slot hybridization, CgCDR1 gene was expressed more than CgCDR2 gene in resistant strains. Though base substitution of ERG11 and ERG3 genes was observed in several base sequences, just one amino acid change was identified in resistant strain. In the results of reverse transcription-polymerase chain reaction, 44 genes were upregulated and 34 genes were downregulated. Among them, adenosine triphosphate-binding cassette transporter-related genes, fatty acid desaturase, lyase, and hypothetical protein genes were upregulated and aldehyde dehydrogenase, oxidoreductase, and prohibitin-like protein genes were downregulated. Other DEGs were also identified. ConclusionThis study showed that CgCDR1 gene was more closely related to fluconazole resistance of C. glabrata than CgCDR2 gene. In addition, several other genes related with fluconazole resistance of C. glabrata were identified.

Direction information in multiple object tracking is limited by a graded resource

Is multiple object tracking (MOT) limited by a fixed set of structures (slots), a limited but divisible resource, or both? Here, we answer this question by measuring the precision of the direction representation for tracked targets. The signature of a limited resource is a decrease in precision as the square root of the tracking load. The signature of fixed slots is a fixed precision. Hybrid models predict a rapid decrease to asymptotic precision. In two experiments, observers tracked moving disks and reported target motion direction by adjusting a probe arrow. We derived the precision of representation of correctly tracked targets using a mixture distribution analysis. Precision declined with target load according to the square-root law up to six targets. This finding is inconsistent with both pure and hybrid slot models. Instead, directional information in MOT appears to be limited by a continuously divisible resource.

All-optical high-speed signal processing with silicon–organic hybrid slot waveguides

Integrated optical circuits based on silicon-on-insulator technology are likely to become the mainstay of the photonics industry. Over recent years an impressive range of silicon-on-insulator devices has been realized, including waveguides1,2, filters3,4 and photonic-crystal devices5. However, silicon-based all-optical switching is still challenging owing to the slow dynamics of two-photon generated free carriers. Here we show that silicon–organic hybrid integration overcomes such intrinsic limitations by combining the best of two worlds, using mature CMOS processing to fabricate the waveguide, and molecular beam deposition to cover it with organic molecules that efficiently mediate all-optical interaction without introducing significant absorption. We fabricate a 4-mm-long silicon–organic hybrid waveguide with a record nonlinearity coefficient of γ ≈ 1 × 105 W−1 km−1 and perform all-optical demultiplexing of 170.8 Gb s−1 to 42.7 Gb s−1. This is—to the best of our knowledge—the fastest silicon photonic optical signal processing demonstrated. A silicon–organic hybrid slot waveguide with a strong optical nonlinearity is demonstrated to perform ultrafast all-optical demultiplexing of high-bit-rate data streams. The approach could form the basis of compact high-speed optical processing units for future communication networks.

Integrated Dual-Band Antenna System Design Incorporating Cell Phone Bezel

This letter describes a method to integrate a cell phone metal bezel in the design of dual-band antenna system. The proposed design includes a hybrid slot and inverted L antennas and covers both the GPS (1.575 GHz) and WLAN (2.4 ~ 4.484 GHZ) frequency bands. A prototype antenna was manufactured on a FR4 board and both S-parameters and radiation patterns are measured, thus validating the simulation results.

Dot and Slot Hybridization of Purified RNA

Dot and Slot Hybridization of Purified RNA

Wide-Band Slot Antennas With CPW Feed Lines: Hybrid and Log-Periodic Designs

In microwave and millimeter wave applications, slot antennas fed by coplanar waveguide (CPW) lines are receiving increasing attention. These antennas have several useful properties, such as a wider impedance bandwidth compared to microstrip patch antennas, and easier integration of solid-state active devices. In this paper novel CPW-fed wideband slot antennas are presented. The design procedure of CPW-fed hybrid slot antennas (HSA) having impedance bandwidths (VSWR<2) up to 57% is described. Theoretical and measured results are shown. We also describe the design procedure of a CPW-fed log-periodic slot antenna (LPSA). The impedance matching and the radiation characteristics of these structures were studied using a method of moment technique. Simulated and measured results for different dielectrics are presented.

Microbial communities in activated sludge performing enhanced biological phosphorus removal in a sequencing batch reactor

Microbial communities of activated sludge in an anaerobic/aerobic sequencing batch reactor (SBR) supplied with acetate as sole carbon source were analyzed to identify the microorganisms responsible for enhanced biological phosphorus removal. Various analytical methods were used such as electron microscopy, quinone, slot hybridization, and 16S rRNA gene sequencing analyses. Electron photomicrographs showed that coccus-shaped microorganisms of about 1 μm diameter dominated the microbial communities of the activated sludge in the SBR, which had been operated for more than 18 months. These microorganisms contained polyphosphate granules and glycogen inclusions, which suggests that they are a type of phosphorus-accumulating organism. Quinones, slot hybridization, and 16S rRNA sequencing analyses showed that the members of the Proteobacteria beta subclass were the most abundant species and were affiliated with the Rhodocyclus-like group. Phylogenetic analysis revealed that the two dominating clones of the beta subclass were closely related to the Rhodocyclus-like group. It was concluded that the coccus-shaped organisms related to the Rhodocyclus-like group within the Proteobacteria beta subclass were the most dominant species believed responsible for biological phosphorus removal in SBR operation with acetate.

Differential biomarker gene and protein expressions in nonylphenol and estradiol-17β treated juvenile rainbow trout ( Oncorhynchus mykiss)

The time- and dose-dependent transcriptional and translational expression of biomarker genes in nonylphenol (NP) and estradiol-17β (E 2) treated juvenile rainbow trout is reported. Fish were exposed to NP (1, 5 and 25 mg/kg) and E 2 (5 mg/kg) and killed at 2, 6, 12, 24, 48 and 72 h after exposure. The estrogen receptor (ER), vitellogenin (Vtg) and eggshell zona radiata protein ( Zr-protein) gene expressions were analyzed in total liver RNA using Northern and slot hybridization with specific cDNA probes. Plasma Vtg and Zr-protein levels were evaluated using indirect ELISA. While Zr-protein gene showed an induction only at 24 h post-exposure, the plasma protein levels showed a time-dependent increase in the 25-mg NP treated group. Vtg transcripts showed an apparent time-dependent increase without a concomitant increase in protein levels in the 25-mg NP treated fish. Time-dependent increases in Vtg and Zr-protein gene expressions without the corresponding increases in ER gene transcription was observed in E 2-treated fish at 2, 6 and 12 h post-exposure. Induction of ER gene transcripts was observed from 24 h and did not change significantly at 48 and 72 h. In the E 2-treated fish, induction of plasma Vtg levels was observed at 48 and 72 h, while plasma Zr-protein was induced at 24, 48 and 72 h, after exposure. We conclude that the E 2- and NP-induced Vtg and Zr-protein gene expressions at the early time intervals after exposure are not dependent on increase in the transcriptional activity of the ER gene and that Vtg and Zr-protein gene transcriptions require only basal or minimal ER concentration, in addition to other mechanisms.

Presence of papillomavirus-like DNA sequences in cutaneous fibropapillomas of the goat udder

Papillomatous lesions were isolated from the mammary skin of goats and examined for evidence of papillomavirus (PV) infection by various criteria, including gross morphology, histology and DNA hybridization. Although some lesions showed gross papillomatous morphological and histological features similar to those caused by papillomavirus in other species, no viral particles were detected. Reverse slot hybridization revealed cross-hybridization between DNA extracted from goat mammary papillomas and human papillomaviruses (HPV). Southern blot, using ovine papillomavirus (OPV) and bovine papillomavirus type 5 (BPV 5) DNA probes under conditions of reduced stringency (Tm −40°C), detected homologous sequences in 40% of the biopsies. DNA fragments corresponding probably to a monomeric form (7000–8000 bp) of an unknown papillomavirus genome were detected. This study provides evidence for the existence of papillomavirus-like sequences in caprine mammary papillomas and suggests that a papillomavirus is likely to be involved in the development of precancerous lesions of goat mammary skin.