Prioritized statistical multiplexing of PCM sources

Using simple multiplexer models, the performances of two prioritization mechanisms for the transmission of PCM coded signals modeled as exponential on/off sources are investigated and compared with nonprioritized transmission using statistical multiplexing and peak allocation. In both mechanisms the source traffic is partitioned into a low-priority stream and a high-priority stream. In the first approach independent channels of different quality of service are used to transport the two-priority streams. In the second approach a single channel is used in conjunction with a selective packet discarding procedure which attempts to restrict loss to the low-priority traffic. For a given source partitioning, new formulae are given to describe the average loss ratio for the low- and high-priority traffic. The effect of loss on quality for PCM coded signal is quantified by a new formula which relates signal-to-reconstruction-noise ratio to low- and high-priority-loss. The results of the investigation show that both methods of prioritized transmission can provide significant improvements in overall service quality when the channel utilization is high     

The medical care of patients with gastrointestinal bleeding after endoscopy

After endoscopic hemostasis, eradication therapy should be given to those who are infected by H. pylori to prevent ulcer relapse and recurrent bleeding. Maintenance acid suppression is not required after successful eradication of H. pylori. Proton pump inhibitor is preferred for the healing of NSAID-induced ulcers. Use of the lowest possible dose, or discontinuation of NSAIDs, is recommended for those with history of ulcer disease. High risk patients who require long-term NSAID therapy should be put on maintenance misoprostal.     

The role of integrins and extracellular matrix in anchorage-independent growth of a mammary carcinoma cell line

Anchorage-independent growth is a property of malignant cells. Extracellular matrix proteins are present in tumor spheroids but their function is not clearly defined. In this paper we show that a murine mammary carcinoma cell line, SP1, which expresses the fibronectin receptor alpha 5 beta 1 requires fibronectin for anchorage-independent growth in soft agar. Growth factors (hepatocyte growth factor and transforming growth factor-beta) also promote SP1 colony growth. In contrast, collagen types I and IV have an inhibitory effect on SP1 colony growth. A clone isolated from SP1 cells which expresses the collagen/laminin receptor alpha 2 beta 1 as well as the fibronectin receptor alpha 5 beta 1, demonstrates increased colony formation in the presence of fibronectin and collagen. These data suggest a role for both the alpha 5 beta 1 and alpha 2 beta 1 integrin receptors in the regulation of anchorage-independent growth of mammary carcinoma cells.     

Mechanism for the Radiolytically Induced Decomposition of Soda–Silicate Glasses

A mechanism is proposed for the radiolysis which occurs in soda-silicate glasses when they are irradiated. The mechanism is consistent with the observations of the reaction products which are produced and the rates at which the decomposition proceeds.     

Microwave preheating of anisotropic conductive adhesive films for high-speed flip chip on flex bonding

Anisotropic conductive adhesive film (ACF) can be preheated by microwave (MW) radiation in order to reduce the bonding time for flip-chip technology. Due to sluggish and nonuniform curing kinetics at the beginning of the curing reaction, thermal curing of epoxy is more time consuming. Therefore, MW radiation may be more effective, due to its uniform heating rate during the cycle. In this paper, MW preheating (for 1–4 sec) of ACF prior to final bonding has been applied to determine the electrical and mechanical performance of the bond. Powers of 80 and 240 W MW were used to study the effect of the MW preheating. A final bonding time of 6–7 sec can be used for flip chip on flex bonding instead of 10–15 sec (standard time for flip chip bonding) for MW preheating time and power used in this study. The contact resistance (as low as 0.01) is low in these samples, whereas the standard resistance is 0.017 ohm (bonded at 180°C for 10 sec without prior MW preheating). The shear forces at breakage were satisfactory (0.167–0.183 KN) for the samples bonded for 6–7 sec with MW preheating. This is very close and even higher than the standard sample (0.173 KN). For MW preheating power of 80 W and sweeping time of 2 sec, final bonding at 6 sec can also be used because of its low contact resistance (0.019 ohm). Scanning electron microscope (SEM) investigation of microjoints and fracture surface shows uneven distribution of conductive particles and thick bond lines in samples bonded for 5 sec (with MW preheating). Samples treated with MW radiation (80 W and 2–3 sec time) serve as evidence that well-distributed particles along with thin bond lines cause low contact resistance and high joint strength.     

High-performance 0.07-μm CMOS with 9.5-ps gate delay and 150 GHzfT

We report room-temperature 0.07-μm CMOS inverter delays of 13.6 ps at 1.5 V and 9.5 ps at 2.5 V for an SOI substrate; 16 ps at 1.5 V and 12 ps at 2.5 V for a bulk substrate. This is the first room-temperature sub-10 ps inverter ring oscillator delay ever reported. PFETs with very high drive current and reduction in parasitic resistances and capacitances for both NFETs and PFETs, realized by careful thermal budget optimization, contribute to the fast device speed. Moreover, the fast inverter delay was achieved without compromising the device short-channel characteristics. At V_dd=1.5 V and I_off ~2.5 nA/μm, minimum L_eff is about 0.085 μm for NFETs and 0.068 μm for PFETs. PFET I_on is 360 μA/μm, which is the highest value ever reported at comparable V_dd and I_off. The SOI MOSFET has about one order of magnitude higher I_off than a bulk MOSFET due to the floating-body effect. At around 0.07 μm L_eff, the NFET cut-off frequencies are 150 GHz for SOI and 135 GHz for bulk. These performance figures suggest that subtenth-micron CMOS is ready for multi-gigahertz digital circuits, and has good potential for RF and microwave applications     

Single-phase operation of a three-phase induction generator withthe Smith connection

Single-phase operation of a three-phase induction generator with the Smith connection (SMIG) is analyzed using the method of symmetrical components. It is shown that, despite the asymmetrical nature of the winding connection, balanced currents can be made to flow in the three-phase stator winding. The conditions for achieving perfect phase balance are carefully deduced. With the aid of a phasor diagram, expressions for the line power factor and line current under perfect phase balance are also obtained. The effect of the phase-balancing capacitances on the generator performance is investigated. A simple dual-mode control scheme is also proposed with a view of minimizing the phase imbalance over the practical operating speed range. Experiments conducted on a 2.2 kW induction machine confirm the validity of the theoretical analysis and feasibility of the control method     

Amplifier linearization using compact microstrip resonant cell-theory and experiment

This paper presents a novel technique for reducing the intermodulation distortions (IMDs) in power amplifiers. In this method, both second- and third-harmonic components generated by the transistor are reflected back simultaneously by the compact microstrip resonant cell (CMRC) at the input port with proper phases to mix with the fundamental signal for the reduction of IMDs. A rigorous mathematical analysis on the effectiveness of multiharmonic reflections has been formulated and derived using the Volterra series. Moreover, the delay mismatch factor of the proposed method is analytically studied and the result shows that a better tolerance to the delay error can be achieved by using CMRC circuitry. Standard two-tone test measurements reveal 32- and 22-dB reductions for the third-order IMD and fifth-order IMD, respectively, without affecting the fundamental signal at 2.45 GHz. Meanwhile, the proposed approach gives a peak power added efficiency of 53% with 11.5 dB transducer gain and 15 dBm output power for a single-stage SiGe bipolar junction transistor. The adjacent channel power ratio (ACPR) is -55dBc for a data rate of 384-kb/s quadrature phase shift keyed modulated signal with 2-MHz spanning bandwidth, and this ACPR is maintained for a broad range of output power level.     

Closed humeral shaft fractures: a prospective evaluation of surgical treatment

OBJECTIVE: We tried to define the roles of the rigid dynamic compression plate (DCP) and the semi-rigid Ender nail (EN) in the treatment of closed humeral shaft fractures. DESIGN: A prospective, randomized clinical study was performed with detailed comparison parameters. MATERIALS AND METHODS: Ninety-one closed humeral shaft fractures were treated. Randomly, 30 humeri were treated with open reduction and internal fixation with DCP and no bone grafting (BG), 29 were treated with the same procedure but with BG, and 32 were treated with closed reduction and internal fixation with Ender nails. The average follow-up period was 32 months (range, 13-54 months). MEASUREMENTS AND MAIN RESULTS: In the group with DCP without BG, the average blood loss was 270 mL, operation time was 92 minutes, hospital length of stay was 6.5 days, and union time was 12.5 weeks. In the group with DCP with BG, the average blood loss was 325 mL, operation time was 108 minutes, hospital length of stay was 6.9 days, and union time was 9.4 weeks. In the EN group, the average blood loss was 114 mL, operation time was 54 minutes, hospital length of stay was 5.6 days, and union time was 9.9 weeks. Analysis of variance and Fisher's exact test were used to evaluate the statistical significance. CONCLUSION: In our experience, for humeral shaft fractures fixed surgically, EN is better than DCP without BG. When DCP is chosen for the means of fixation, prophylactic BG is recommended, especially in cases with more comminution.     

Performance analysis of a three-phase induction generator connectedto a single-phase power system

This paper analyzes the performance of a three-phase induction generator which is connected to a single-phase power system. Significant improvement in machine performance can be obtained by using a single static phase-converter, provided that the machine is driven in the reverse direction. If two phase-converters, are employed, perfect phase balance can be obtained at any desired value of slip. The theoretical analysis is validated by experiments on a 2-kW test machine