A technique for extracting physiological parameters and therequired input function simultaneously from PET image measurements:theory and simulation study

Positron emission tomography (PET) is an important tool for enabling quantification of human brain function. However, quantitative studies using tracer kinetic modeling require the measurement of the tracer time-activity curve in plasma (PTAC) as the model input function. It is widely believed that the insertion of arterial lines and the subsequent collection and processing of the biomedical signal sampled from the arterial blood are not compatible with the practice of clinical PET, as it is invasive and exposes personnel to the risks associated with the handling of patient blood and radiation dose. Therefore, it is of interest to develop practical noninvasive measurement techniques for tracer kinetic modeling with PET. In this paper, a technique is proposed to extract the input function together with the physiological parameters from the brain dynamic images alone. The identifiability of this method is tested rigorously by using Monte Carlo simulation. The results show that the proposed method is able to quantify all the required parameters by using the information obtained from two or more regions of interest (ROIs) with very different dynamics in the PET dynamic images. There is no significant improvement in parameter estimation for the local cerebral metabolic rate of glucose (LCMRGlc) if there are more than three ROIs. The proposed method can provide very reliable estimation of LCMRGlc, which is our primary interest in this study     

Ordered dynamic channel assignment scheme with reassignment inhighway microcells

An ordered dynamic channel assignment with reassignment (ODCAR) scheme is proposed, and its performance is studied in a highway microcellular radio environment. Channels are assigned in an ordered basis in conjunction with a minimax algorithm under cochannel interference constraints, to provide high capacity and to alleviate worst case channel congestion in each microcell. Simulation results show significant performance improvements in terms of channel utilization and probability of call failure, at the expense of an increase in complexity and call switching requirements     

Computer interface design: A user-centered approach

Enhancing the way people use computers to perform tasks has become a very important issue in interface design and human-computer interactions. When the concept of human-computer interaction first began to emerge it was commonly understood as the hardware and software through which a human and computer could effectively communicate (Laurel, 1990). This effective communication is also know as user-friendliness. The concept of user friendliness has recently been expanded to include various attributes and cognitive aspects of the user's needs and experiences. Focus should be on the user's experiences, expectations, preferences, and cognitive aspects in developing efficient and effective computer interface designs. It is the basic premise of this paper to emphasize using a user-centered design in developing computer interfaces.     

Deorthogonalization of ODS-CDMA QPSK by AM/PM Nonlinearity

When using a conventional demodulator, a sufficient condition to maintain ODS-CDMA codeword orthogonality is constant relative channel amplitude over the codeword duration. When transmitted over a memoryless, AM/PM nonlinearity channel, the chip-to-chip fluctuating amplitude of a composite ODS-CDMA QPSK waveform produces a chip-to-chip fluctuating phase that deorthogonalizes the ODS-CDMA codewords, resulting in an additional multiple access self-interference similar to that found in asynchronous DS-CDMA. For ODS-CDMA QPSK in an AM/PM nonlinearity channel, we utilize the Central Limit Theorem, derive, and evaluate: (i) an expression for the signal-to-distortion ratio at the demodulator output, (ii) an expression for the uncoded bit error probability, and (iii) an upper bound on the convolutionally-coded bit error probability. We find that the degradation to BER depends on both the AM/PM nonlinearity slope and the ODS-CDMA channel loading.     

Effects of category prototypes on performance-rating accuracy.

Two studies examined whether the accessibility of performance prototypes influences performance appraisals. Pilot studies revealed students used performance prototypes when rating instructor performance. Study 1 manipulated the accessibility of these prototypes and the time delay of performance ratings. Results showed no effect of the prime on rating error and accuracy; however, discrimination accuracy decreased over time and recognition bias became more conservative. Study 2 manipulated prototype accessibility and type of rating stimuli (videotape vs. vignette). Rating accuracy and recall were higher for vignette than videotape stimuli, and only those participants exposed to the vignette exhibited priming effects. Results supported transfer-appropriate processing and implied that cognitive primes may have a stronger effect on performance ratings based on "paper-people" than videotaped stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dusts,scale, slags,sludges... Not wastes,but sources of profits

Historically, the steel industry has focused on the need for and the many benefits of recycling steel that is discarded either in its own or in its customers’ manufacturing processes, as well as in recovery and reuse of steel scrap that arises after the product has served its intended purpose. In fact, modern steelmaking relies on the use of recycled iron units for at least half of its production. The other side of the story is the fate of the non-steel by-products (e.g., oxide dusts, sludges, scales, slags, spent refractories and the contained “low grade” energy units that are generated as natural adjuncts to iron and steelmaking processes). These valuable by-products often are classified as “wastes” and are discarded to landfills, at significant cost, although in reality they offer significant potential for cost savings or profit if reintroduced into the industrial arena via well planned programs. Examples of such instances will be presented, including energy credit issues, in the hope of pointing the way for future expansion of benefits from these opportunities. Preparing for a challenge and honor such as the Howe Memorial Lecture, one has to stand in awe of the accomplishments of the predecessor we honor in this forum. He worked in the early days of our industry without the benefits of the many technological improvements he and his successors brought to play as the years went by. John Stubbles, in his Howe Memorial Lecture in 1997,_[1] presented a masterful and entertaining biography of Howe and his very active and prolific life. Perhaps the most telling quotation he attributed to Howe is very pertinent to the topic we will address presently: “Metallurgy lives by profit, not logic,” to which I would like to add a comment that bears on the topic of this lecture from the 1991 Howe lecturer, my friend and mentor Bill Dennis, “Where there is muck, there is money.” There are numerous examples of “one hand washes the other” in this business; that is, of the synergism between needs and capabilities. We will address some of these situations, such as in a new process under development for dezincing of post consumer scrap, and in the use of iron units in by-product oxides and recycling of ladle slags and of spent refractories. Peter J. Koros, the Iron and Steel Society’s 77th Howe Memorial Lecturer (2001), is Principal of Koros Associates, Inc. (Pittsburgh, PA), a consultancy he founded following retirement from the former LTV Steel Company where he worked for nearly 41 years, retiring as Senior Research Consultant. He earned the Bachelor of Science degree in Metallurgical Engineering from Drexel University, and his master’s and doctoral degrees in Metallurgy from the Massachusetts Institute of Technology (MIT). In 1958, he joined Jones and Laughlin Steel (which became LTV Steel Company), where he held positions in research (Director, Process Metallurgy), Technical Services and Quality Control, with most activities focused on steelmaking and related areas. He was responsible for J&L’s development work in injection technology for desulfurization of hot metal and steel, was the inventor of the patented co-injection concept now in use worldwide, and had the lead role in LTV Steel’s programs for degalvanizing scrap and for recovery and utilization of by-product oxides. He led the AISI Opt-In program for degalvanizing scrap and the LTV-USS pilot program for processing “by-product” oxides. Koros has authored more than 75 publications and presentations, and holds eight U.S. patents, the latest issued in 2000. Dr. Koros was elected a Distinguished Member and Fellow of the ISS in 1984 and a Fellow of ASM International in 1988. Other honors include the ISS Distinguished Service Award (1998), ISS Electric Furnace Honorable Mention Citation (1987), International Magnesium Association Design and Applications Award (1978), AISI Gold (1977) and Silver (1969) Medals, ISS Herty (1963), McKune (1963), and Toy (1962) Awards. Koros served on the Technical Advisory Committee of the AISI-DOE Direct Steelmaking Program and its follow-on Waste Oxide Recycling Program. He was chairman of the AISI Task Force on Degalvanizing Steel Scrap and of the Industrial Advisory Panel to the Argonne Lab-MRI Program on Dezincing Steel Scrap. The 2001 Howe Memorial Lecture, titled “Dusts, Scale, Slags, Sludges ... Not Wastes But Sources of Profits,” as well as an invited Keynote Lecture for an International Recycling Conference in Sweden (June 2002, “Iron Units in Search of a Home: New Steel”) were based on the experience from these programs. Koros has been an active member of the ISS Advanced Technology Committee for which he participated in and chaired several symposia, including New Melting Technologies II (October 2002) and the first New Melting Technologies Symposium (1997). He was Director of the ISS 2000 Short Course on Injection Technology, a lecturer in the 2000 ISS/AISI Course on BOF Steelmaking, lead Co-chairman for the Elliott Symposium (1990), and Chairman of the Program Committee for the Fifth International Iron and Steel Congress (1986). Dr. Koros served on the Industrial Advisory Board of MIT’s Materials Processing Center (1995–98) and the AISI’s Iron and Steel Research Subcommittee (1976–86.) He was chairman of the ISS National Science Foundation Advisory Committee, the Advisory Council of the U.S. Bureau of Mines Generic Minerals Technology Center for Pyrometallurgy Research (1983–85), and of the Advisory Board for Carnegie Mellon University’s Center for Iron and Steel Research, for which he served as chairman (1991–1992). Service included participation in the NRC-NAS Alternative Energy and Development Strategy Study (1989–90.) Koros was very active in the creation of the ISS, having served as Chairman of the predecessor TMS Iron and Steel Division in 1972–73 and on the AIME Board of Directors (1974). Professional Society memberships: ISS (elected Distinguished Member and Fellow, Life Member), TMS (Senior or Life Member), ASM International (elected Fellow, Life Member), and AISE.     

Long wavelength quantum well lasers: Synopsis of the RACE “AQUA” project: MOVPE/MBE/GSMBE for InGaAsP/InP and InGaAlAs/InP high speed MQW DFB lasers

The technological limits for ultra high speed devices are now rapidly expanding due to the use of quantum well (QW) materials. This new class of materials gives the opportunity of tailoring materials parameters by controlling geometries on an atomic scale. They look very promising as materials for lasers, detectors and transistors suitable even above 10 Gb/s. It will be demonstrated that state of the art MQW structures can be realized in both material systems, InGaAsP/InP and InGaAlAs/InP. Parallel lateral laser structures (e.g. SIBH, BRS and TBH) have been designed to take full benefit of QW technology. Ultimate reduction of parasitics, whilst using potential low cost fabrication technologies is the basis for achieving high bitrate (10 Gb/s) MQW lasers, even with the stronger damping in QW material. Using the DFB-SIBH laser structure 10 Gb/s large signal experiments are successfully performed with bulk, MQW and SLMQW lasers. Extremely low fall times of 44 ps are achieved. Additional MQW based improvements are observed such as: −3 times higher differential gain, increased output power (>110 mW), 2.5 times lower chirp (Δλ_−20dB = 0.40 nm at 10 Gb/s modulation), and 2 dB gain in power budget at 10 Gb/s digital transmission.     

A PLL clock generator with 5 to 10 MHz of lock range formicroprocessors

A microprocessor clock generator based on an analog phase-locked loop (PLL) is described for deskewing the internal logic control lock to an external system lock. This PLL is fully generated onto a 1.2-million-transistor microprocessor in 0.8-μm CMOS technology without the need for external components. It operates with a lock range from 5 to 110 MHz. The clock skew is less than 0.1 ns, with a peak-to-peak jitter of less than 0.3 ns for a 50-MHz system clock frequency