Channeling Technique Research Articles

The Contemporary Indications for Augmentation Cystoplasty

Augmentation cystoplasty (AC) is a well-established technique for improving bladder compliance and capacity, preserving renal function, and minimizing incontinence due to severe detrusor overactivity. The popularity of AC has declined over the past decade due to the improved efficacy of other conservative therapies such as botulinum toxin. However, AC plays an important role in the management of refractory patients. Many patients requiring AC will also benefit from the creation of a continent catheterizable channel and bladder outlet surgery. Various augmentation and continent channel techniques are described, along with associated complications. In the appropriate patient, AC is an excellent treatment option that can improve bladder function and improve patients’ quality of life.

Minority anion substitution by Ni in ZnO

We report on the lattice location of implanted Ni in ZnO using the β− emission channeling technique. In addition to the majority substituting for the cation (Zn), a significant fraction of the Ni atoms occupy anion (O) sites. Since Ni is chemically more similar to Zn than it is to O, the observed O substitution is rather puzzling. We discuss these findings with respect to the general understanding of lattice location of dopants in compound semiconductors. In particular, we discuss potential implications on the magnetic behavior of transition metal doped dilute magnetic semiconductors.

Lattice Codes for the Gaussian Relay Channel: Decode-and-Forward and Compress-and-Forward

Lattice codes are known to achieve capacity in the Gaussian point-to-point channel, achieving the same rates as i.i.d. random Gaussian codebooks. Lattice codes are also known to outperform random codes for certain channel models that are able to exploit their linearity. In this paper, we show that lattice codes may be used to achieve the same performance as known i.i.d. Gaussian random coding techniques for the Gaussian relay channel, and show several examples of how this may be combined with the linearity of lattices codes in multisource relay networks. In particular, we present a nested lattice list decoding technique in which lattice codes are shown to achieve the decode-and-forward (DF) rate of single source, single destination Gaussian relay channels with one or more relays. We next present two examples of how this DF scheme may be combined with the linearity of lattice codes to achieve new rate regions which for some channel conditions outperform analogous known Gaussian random coding techniques in multisource relay channels. That is, we derive a new achievable rate region for the two-way relay channel with direct links and compare it to existing schemes, and derive a new achievable rate region for the multiple access relay channel. We furthermore present a lattice compress-and-forward (CF) scheme for the Gaussian relay channel which exploits a lattice Wyner-Ziv binning scheme and achieves the same rate as the Cover-El Gamal CF rate evaluated for Gaussian random codes. These results suggest that structured/lattice codes may be used to mimic, and sometimes outperform, random Gaussian codes in general Gaussian networks.

A reconfigurable iterative algorithm for the K-user MIMO interference channel

Interference alignment (IA) is a recently proposed transmission technique for the K-user interference channel (IFC), which is proven to achieve a sum-rate multiplexing gain of K/2 at the high interference regime. Motivated by our recent work [1] that showed how the sum-rate scaling can range between K/2 and K for moderate-to-low interference conditions, in this paper we present a novel iterative algorithm for the K-user multiple-input multiple-output (MIMO) IFC with arbitrary number of transceiver antennas. The proposed algorithm automatically adjusts itself to the interference regime at hand, in the above sense, as well as to the wireless channel in order to achieve the appropriate sum-rate scaling. Our reconfigurable algorithm combines the system-wide mean squared error minimization criterion with the single-user waterfilling solution to maximize each user's transmission rate according to the interference levels and channel conditions. Extensive computer simulation results for the sum-rate performance of the proposed reconfigurable algorithm over various Ricean fading channels are presented. It is shown that, in the interference-limited regime, the proposed algorithm reconfigures itself so as to achieve the IA scaling whereas, in the moderate-to-low interference regime, it chooses interference-myopic MIMO transmissions for all K communication pairs.

Regrowth characteristics of SiGe/Si by IBIEC and SPEG

Single crystalline Si1−xGex/Si with three kinds of Ge contents (x: 0.05, 0.1, and 0.2) with thicknesses of 400–440nm were amorphized by 500keV (x: 0.05 and 0.1) and 600keV (x: 0.2) Ge ion beam bombardment to a fluence of 1.0×1016ions/cm2 at room temperature. The regrowth behavior of the damaged layers were compared between ion beam induced epitaxial crystallization (IBIEC) by 2.0MeV Ge ions at 300°C to fluences of 1.0–3.0×1016ions/cm2 and solid phase epitaxial growth (SPEG) carried out in a flowing N2 ambient for up to 40min at 600°C. Rutherford backscattering spectroscopy (RBS) with channeling techniques revealed that crystallinity improvement by IBIEC tended to be saturated with increasing fluence while crystallinity improvement by SPEG was proceeded with increasing annealing time and relatively high quality SiGe layers were obtained. Crystallinity improvement was more rapid and pronounced for SiGe with higher Ge concentration both in IBIEC and SPEG. In contrast to the case of SPEG at 600°C, transmission electron microscope (TEM) image in SiGe treated by IBIEC showed that bunches of dislocation loops remained as islands surrounded by single crystalline lattice layers image, leading to the high RBS aligned yield even after completion of the layer-by-layer regrowth.

Identifying the Information Gain of a Quantum Measurement

We show that quantum-to-classical channels, i.e., quantum measurements, can be asymptotically simulated by an amount of classical communication equal to the quantum mutual information of the measurement, if sufficient shared randomness is available. This result generalizes Winter's measurement compression theorem for fixed independent and identically distributed inputs [Winter, CMP 244 (157), 2004] to arbitrary inputs, and more importantly, it identifies the quantum mutual information of a measurement as the information gained by performing it, independent of the input state on which it is performed. Our result is a generalization of the classical reverse Shannon theorem to quantum-to-classical channels. In this sense, it can be seen as a quantum reverse Shannon theorem for quantum-to-classical channels, but with the entanglement assistance and quantum communication replaced by shared randomness and classical communication, respectively. The proof is based on a novel one-shot state merging protocol for "classically coherent states" as well as the post-selection technique for quantum channels, and it uses techniques developed for the quantum reverse Shannon theorem [Berta et al., CMP 306 (579), 2011].

A Blind Hammerstein Diversity Combining Technique for Flat Fading Channels

Diversity combining techniques play an important role in combating the destructive effects of channel fading in wireless communication systems. In this work we present a blind diversity combining technique for Rayleigh flat fading channels based on Hammerstein type filters. We show that the performance of this technique is very close to ideal MRC system which is accepted as an optimum receiver over fading channels in presence of AWGN. This is a valuable result especially because higher bandwidth efficiency is also achieved as compared with MRC. We also show that in our proposed technique the variation of the combiner output values around the values of transmitted symbols is less than the corresponding variation in MRC system. Hence, for soft decision applications it is superior to MRC technique.

Room-temperature detection of spin accumulation in silicon across Schottky tunnel barriers using a metal–oxide–semiconductor field effect transistor structure (invited)

Using a metal-oxide-semiconductor field effect transistor structure with a high-quality CoFe/n+-Si contact, we systematically study spin injection and spin accumulation in a nondegenerated Si channel with a doping density of ∼4.5 × 1015 cm−3 at room temperature. By applying the gate voltage (VG) to the channel, we obtain sufficient bias currents (IBias) for creating spin accumulation in the channel and observe clear spin-accumulation signals even at room temperature. Whereas the magnitude of the spin signals is enhanced by increasing IBias, it is reduced by increasing VG interestingly. These features can be understood within the framework of the conventional spin diffusion model. As a result, a room-temperature spin injection technique for the nondegenerated Si channel without using insulating tunnel barriers is established, which indicates a technological progress for Si-based spintronic applications with gate electrodes.

Quality Evaluation Method for Underwater Image Communication

A simulation based on Gilbert-Elliot packet loss model is developed to simulate an image transmitting system in underwater acoustic channel. This developed system is applied as a platform to study the relation between image quality assessment parameter PSNR, image activity measure (IAM) and channel ’ s packet loss rate. A group of sample images were transmitted in this communication system and a formula of PSNR, the initial value of IAM, and packet loss rate was fitted by the data from the degra ded sample images . With the help of the fitted formula, then we are able to predict the possible quality of image transmi ssion, and beforehand choices of channel or source processing techniques in the communication system becomes possible, too. Experimental results indicate that the predicting method of underwater image transmitting quality based on Gilbert-Elliot model can provide certain references for establishing strategies of underwater image transmission.

An efficient user scheduling scheme for downlink Multiuser MIMO-OFDM systems with Block Diagonalization

The combination of multiuser multiple-input multiple-output (MU-MIMO) technology with orthogonal frequency division multiplexing (OFDM) is an attractive solution for next generation of wireless local area networks (WLANs), currently standardized within IEEE 802.11ac, and the fourth-generation (4G) mobile cellular wireless systems to achieve a very high system throughput while satisfying quality of service (QoS) constraints. In particular, Block Diagonalization (BD) scheme is a low-complexity precoding technique for MU-MIMO downlink channels, which completely pre-cancels the multiuser interference. The major issue of the BD scheme is that the number of users that can be simultaneously supported is limited by the ratio of the number of base station transmit antennas to the number of user receive antennas. When the number of users is large, a subset of users must be selected, and selection algorithms should be designed to maximize the total system throughput. In this paper, the BD technique is extended to MU-MIMO-OFDM systems and a low complexity user scheduling algorithm is proposed to find the optimal subset of users that should transmit simultaneously, in light of the instantaneous channel state information (CSI), such that the total system sum-rate capacity is maximized. Simulation results show that the proposed scheduling algorithm achieves a good trade-off between sum-rate capacity performance and computational complexity.

High-Rate Maximum Runlength Constrained Coding Schemes Using Nibble Replacement

In this paper, we will present coding techniques for the character-constrained channel, where information is conveyed using <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -bit characters (nibbles), and where <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">w</i> prescribed characters are disallowed. Using codes for the character-constrained channel, we present simple and systematic constructions of high-rate binary maximum runlength constrained codes. The new constructions have the virtue that large lookup tables for encoding and decoding are not required. We will compare the error propagation performance of codes based on the new construction with that of prior art codes.

Nanoscale CMOSFET performance improvement and reliability study for local strain techniques

In this paper, we report the investigation on a nanoscale complementary metal–oxide–semiconductor field-effect transistor (CMOSFET) fabricated by local strained channel techniques with epitaxial silicon–germanium (SiGe) and high mechanical stress SiN as contact etch stop layer (CESL). By integrating the SiGe layer with compressive stress and the SiN film with compressive and tensile strain, both PMOS and NMOS have better drain-to-source saturation current (Isat). For short channel effect, strain scheme also show beneficial results based on Vt-roll off performance. Furthermore when capping a strained tensile film, the interface trap density for NMOS could lower down 32% comparing to control Si from charge pumping current measurement which can indicate more stable initial gate oxide quality for NMOS. The impact of these stressor schemes on device reliability, such as negative bias temperature instability (NBTI) and hot carrier injection (HCI) have been studied to conclude that the hydrogen from compressive SiN is the key for reliability performance.

Use of channeling for the study of radiation effects in nuclear materials

The evaluation of radiation damage in materials submitted to intense irradiation is a challenging problem for the nuclear industry. Ion beams provide efficient tools to both simulate the interactions involved during the slowing-down of energetic particles and characterize the damage induced by irradiation with the channeling technique. This article presents new results and modeling regarding the disorder depth distribution and the damage build-up in nuclear materials irradiated with low- and high-energy ions which allow exploring the nuclear collision and electronic excitation regimes. A new phenomenon (SHIBIEC), leading to the recovery by electronic excitation of the damage created by ballistic collisions, is also discussed.

Solid phase epitaxy of ultra-shallow Sn implanted Si observed using high-resolution Rutherford backscattering spectrometry

We present detailed observations of the solid phase epitaxy process in Sn-implanted Si samples with nanometric depth resolution within a 50 nm ultra-shallow region beneath the surface. Measurements were made using high-resolution Rutherford backscattering spectrometry coupled with the ion channeling technique. Samples with Sn ions implanted onto Si substrates with and without prior Si+ self-amorphization implantation process show different crystal regrowth characteristics during annealing. Regrowth proceeds at a non-uniform rate up to a certain depth before stopping, and an Arrhenius-type defect density limiting model of crystal regrowth is proposed to account for this effect.

Analytical Modeling for Handling Poor Signal Quality Calls in Cellular Network

Mobility and radio resource management plays a major role in Quality of Service provisioning for cellular communication systems. Due to the limited radio coverage of a cell, an ongoing call while being handed off may get dropped. We develop an effective and efficient handoff scheme using mobile controlled handoff and fractional guard channel techniques, where mobile station measures the signal strength from surrounding base stations and interference level on all channels. A handoff can be initiated if the signal strength of the serving base station is lower than that of other base station by certain threshold. Two models are proposed to calculate the blocking probability of new calls and the dropping probability of handoff calls, using call admission control scheme in a cellular system. Numerical analyses of both the models are carried out to investigate the impact on performance of the parameters and comparisons with conventional channel reservation schemes.

Formation of thermal evaporated Ge Nano-Islands by high temperature annealing

High Vacuum thermal evaporation was used to grow germanium islands on the silicon substrate covered by silicon oxide. The Ge nano-islands were formed by thermal annealing at different temperatures from 500 °C to 700 °C. Formation of islands was studied by various analytical techniques. The thickness of Ge layer was determined by rutherford backscattering spectroscopy (RBS). Also, combined with channeling technique, the composition and probable contaminants during synthesis processes were investigated. To explore the islands size and shape, both atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were used. Then the topographical images of surfaces were studied by AFM. The outcome of experimental evaluations of growth mechanism has indicated that with increasing the annealing temperature up to 700 °C, Ge islands were appeared from a uniform layer. Moreover, the statistical assessments of surfaces have shown that the nano-island’s sizes can be varied from several hundred nanometers to 30 nm by growing the annealing temperature. The reduction of the size along with an increase of the number of nano-islands after each thermal treatment is a major factor to prohibit us from seeing their clear images in AFM. The possibility of running statistical estimation on islands, instead, is the powerful tool of extracting and probing the distribution and the shape of Ge island’s peak in AFM images.

A new technique for ferroelectric microfluidic channels by rolling method

Microfluidic channels on the size of tens of microns are being developed for use in a variety of applications such as microreactors, DNA analysis, and micro total analysis systems. Among the fabrication techniques for microfluidic channels, the recently-developed rolled-up method provides a great opportunity to integrate tubular channels by selective underetching and release of a strained thin film from a substrate. In this work, microfluidic channels with large diameter-to-length aspect ratios have been fabricated by a rolling method. The micro-FTIR characterization demonstrated that the functional poly(VDF-TrFE) ferroelectric polymer was engineered in the micro channel. The ferroelectric properties of the microchannels were studied by piezoresponse force microscopy (PFM). Local hysteresis measurement suggests that the microchannels show good ferroelectric properties. Fluid moving and emptying of the microfluidic channels were captured by video microscopy.

Effects of concentration and thermal annealing on the optical activation of Er implanted into GaN layers

The wide band gap semiconductor, GaN, has emerged as an important host for rare earth-electroluminescence. The annealing behaviour and lattice site location of Er implanted into GaN were studied with the Rutherford Backscattering Spectrometry (RBS)/channelling and photoluminescence (PL) techniques. Also Er site dependence on the annealing temperature and implantation dose has been studied in detail. The optical properties of the Er-doped GaN system, evidencing their dependence on the parameters adopted during the synthesis procedure (Er implantation dose, annealing temperature) have been discussed. RBS/channelling measurements suggested that mostly Er occupy substitutional site and depends on the Er concentration. The main result is the activation of a typical Er giving rise to PL emission in the 1450–1650 nm range, related to radiative 4 I 13/2→4 I 15/2 transitions. Depending on the Er dose, we observe a specific behaviour linked to variation of the annealing temperature that strongly determines PL emission band. We observed a PL spectral shape with the main peak located at 1542 nm and shoulder peak at 1558 nm (and full width at half maximum (FWHM) of 33 nm) with a series of weaker PL structures at 1519, 1572 and 1591 nm, due to the Stark sub-level splitting.

Joint Source and Relay Design for Multiuser MIMO Nonregenerative Relay Networks With Direct Links

In this paper, we investigate joint source precoding matrices and relay processing matrix design for multiuser multiple-input-multiple-output (MIMO) nonregenerative relay networks in the presence of the direct source-destination links. We consider both capacity and mean-square-error (MSE) criteria subject to the distributed power constraints, which are nonconvex and apparently have no simple solutions. Therefore, we propose an optimal source precoding matrix structure based on the point-to-point MIMO channel technique and a new relay processing matrix structure under the modified power constraint at relay node, based on which a nested iterative algorithm of jointly optimizing sources precoding and relay processing is established. We show that the capacity-based optimal source precoding matrices share the same structure with the MSE-based matrices and so does the optimal relay processing matrix. Simulation results demonstrate that the proposed algorithm outperforms the existing results.

Feedback-Topology Designs for Interference Alignment in MIMO Interference Channels

Interference alignment (IA) is a joint-transmission technique that achieves the capacity of the interference channel for high signal-to-noise ratios (SNRs). Most prior work on IA is based on the impractical assumption that perfect and global channel-state information(CSI) is available at all transmitters. To implement IA, each receiver has to feed back CSI to all interferers, resulting in overwhelming feedback overhead. In particular, the sum feedback rate of each receiver scales quadratically with the number of users even if the quantized CSI is fed back. To substantially suppress feedback overhead, this paper focuses on designing efficient arrangements of feedback links, called feedback topologies, under the IA constraint. For the multiple-input-multiple-output (MIMO) K-user interference channel, we propose the feedback topology that supports sequential CSI exchange (feedback and feedforward) between transmitters and receivers so as to achieve IA progressively. This feedback topology is shown to reduce the network feedback overhead from a cubic function of K to a linear one. To reduce the delay in the sequential CSI exchange, an alternative feedback topology is designed for supporting two-hop feedback via a control station, which also achieves the linear feedback scaling with K. Next, given the proposed feedback topologies, the feedback-bit allocation algorithm is designed for allocating feedback bits by each receiver to different feedback links so as to regulate the residual interference caused by the finite-rate feedback. Simulation results demonstrate that the proposed bit allocation leads to significant throughput gains especially in strong interference environments.