Development into blastocysts of bovine oocytes cryopreserved by ultra-rapid cooling

The objective of the research described was to devise an efficient procedure to cryopreserve in vitro-matured bovine oocytes, using in vitro fertilization (IVF) and development of resultant zygotes into blastocysts as criteria of oocyte survival. Oocytes at metaphase II were found to be extremely sensitive to chilling. Cooling them to O degrees C for as little as 5 sec significantly decreased their capability to cleave and develop further after IVF; after 80 sec at 0 degrees C, only approximately 10% of chilled oocytes developed into blastocysts. Oocytes were also adversely affected by brief exposures to 4 M and 5.5 M ethylene glycol (EG) solutions supplemented with sucrose; after being suspended in either of these EG solutions in plastic straws and plunged directly into liquid nitrogen (LN2), few of the oocytes were fertilized and developed. To "outrace" chilling injury, oocytes contained in < 1 microliter of EG solution were placed onto electron microscope grids and plunged directly into N2 slush or LN2. After such ultra-rapidly cooled oocytes were warmed, 30% of them cleaved after IVF, and half of these developed into blastocysts-- survival rates equivalent to those for oocytes that had been exposed to EG without any cooling. This method offers promise as a novel way to cryopreserve bovine oocytes.     

Estimation of the inter-bar resistance of a cast cage rotor

This paper describes an experimental investigation of bar-to-bar resistance. It addresses the interpretation of experimental data, and the use of that data to develop a means of estimating bar-to-bar resistance at the design stage.     

MicroRNAs as Potential Biomarkers in the Differential Diagnosis of Lipomatous Tumors and Their Mimics

Adipocytic tumors are the most common subtype of soft tissue tumors. In current clinical practice, distinguishing benign lipomas from well-differentiated liposarcomas (WDLPS), as well as dedifferentiated liposarcomas (DDLPS) from their morphologic mimics, remains a significant diagnostic challenge. This is especially so when examining small biopsy samples and without the aid of additional ancillary tests. Recognizing the important role that microRNAs (miRNAs) play in tumorigenesis and their potential utility in tumor classification, we analyzed routine clinical tissue samples of benign and malignant lipomatous tumors, as well as other sarcoma mimics, to identify distinguishing miRNA-based signatures that can aid in the differential diagnosis of these entities. We discovered a 6-miRNA signature that separated lipomas from WDLPS with high confidence (AUC of 0.963), as well as a separate 6-miRNA signature that distinguished DDLPS from their more aggressive histologic mimics (AUC of 0.740). Functional enrichment analysis unveiled possible mechanistic involvement of these predictive miRNAs in adipocytic cancer-related biological processes and pathways such as PI3K/AKT/mTOR and MAPK signaling, further supporting the relevance of these miRNAs as biomarkers for adipocytic tumors. Our results demonstrate that miRNA expression profiling may potentially be used as an adjunctive tool for the diagnosis of benign and malignant adipocytic tumors. Further validation studies are warranted.     

Direction finding receiver for UWB impulse radio signal in multipath environment

In this paper, we propose a direction finding (DF) receiver for ultra wideband impulse radio (UWB‐IR) signal in a realistic multipath environment. The receiver uses an array of antenna, where each antenna is connected to a proposed propagation‐delay estimation structure. The advantage of the proposed structure is that it outputs a trapezoidal signal whose amplitude reflects the propagation delay and thus relaxes the sampling rate requirement of the analog‐to‐digital‐converter (ADC). The angle‐of‐arrival (AOA) is estimated from the vector of propagation delays measured with respect to reference antenna. Because these estimated delays contain outliers, we propose a simple AOA estimation algorithm based on minimum fractional‐distance search. Experimental results based on simulation show that the proposed DF receiver achieves better performance compared with the minimum ?₁‐ and ?₂‐based (least‐squares based) distance search. Copyright © 2010 John Wiley & Sons, Ltd.     

Minimum time control of conductive heating systems formicroelectronics processing

A minimum time control scheme is designed to improve repeatability by minimizing the loading effects induced by the common processing condition of placement of a semiconductor wafer at ambient temperature on a large thermal-mass bake plate at processing temperature. The minimum time control strategy provides an optimal solution for minimizing the worst case deviation from a nominal temperature set-point during the load disturbance condition. This results in a predictive controller that performs a predetermined heating sequence prior to the arrival of the wafer as part of the resulting feedforward/feedback strategy to eliminate the load disturbance. The controller is easy to design and implement and makes it more suitable for online implementation such as automatic online tuning of a feedforward controller. Experimental results depict an order-of-magnitude improvement in the settling time and the integral-square temperature error between the optimal predictive controller and a feedback controller for a typical load disturbance     

Flux-based two-degrees-of-freedom algorithm for three-phase electronic converter control

This letter integrates the tracking robustness of two-degrees-of-freedom control and fast dynamic response of flux-based, pulse-width modulation to develop a new current controller for high performance, three-phase electronic converter control. Theoretical analysis shows that the controller can simultaneously achieve good steady-state, transient and harmonic performance, which are challenges not previously met by existing current controllers reported in the literature. Experimental results are presented to verify the performance and practicality of the proposed controller.     

Modeling and analysis of correlated software failures of multiple types

Most software reliability models assume independence of successive software runs. It is a strict assumption, and usually not valid in reality. Goseva-Popstojanova & Trivedi (2000) presented an interesting study on failure correlation among successive software runs. In this paper, by extending their results, a software reliability model is developed based on a Markov renewal process for the modeling of the dependence among successive software runs, where more than one type of failure is allowed in general formulation. Meanwhile, the cases of restarting with repair, and without repair, are considered. Although such a model is more complex than the traditional approach based on reliability growth, it incorporates more information about the failures, and system structure. A numerical example is also shown to illustrate the procedure, and provide some comparison.     

Three-Level AC–DC–AC Z-Source Converter Using Reduced Passive Component Count

This paper presents a three-level AC-DC-AC Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low-cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can produce the correct volt-second average at its output, while simultaneously achieving inductive voltage boosting by shooting through either an appropriately selected inverter phase-leg or two phase-legs being commanded simultaneously. More interestingly, these performance features are achieved with no increase in the number of semiconductor commutations, and hence, no increase in switching losses. The proposed converter therefore offers a low-cost alternative to applications that need to ride through frequent input voltage sags. For confirming the converter performance, experimental testing using a constructed laboratory prototype is performed with its captured results presented in a later section of the paper.     

Transient Modeling and Analysis of Pulse-Width Modulated Z-Source Inverter

The newly proposed Z-Source inverter has been proven in the literature to exhibit both steady-state voltage buck and boost capabilities using a unique LC impedance network coupled between the power source and converter circuit. This paper now presents transient modeling and analysis of a voltage-type Z-source inverter. These aspects are found to be challenging and they need to be carefully investigated before attempting to design advanced control algorithms for controlling the Z-source inverter. Through detailed analysis, the paper identifies several phenomena on the dc and ac-sides of the inverter, which would result in the inverter having a non-minimum-phase transient response. The dc-side phenomenon is associated with the Z-source impedance network, which is shown through small-signal and signal-flow-graph analyses to be having a right-half-plane zero in its control-to-output transfer function. Also, the ac-side phenomenon is shown through space vector analysis to depend on the time intervals of inverter states used for reconstructing the desired inverter output voltage. Based on the ac vectorial analysis, a method for improving the inverter transient response is also presented. Last, simulation results obtained using a switching-functional model and experimental results obtained using a laboratory prototype are presented for validating the described theoretical concepts