bluuebunny/crossref_metadata_2025 huggingface dataset:
d‐Amino acid oxidase and serine racemase in human brain: normal distribution and altered expression in schizophrenia
Authors: Verrall Louise , Walker Mary , Rawlings Nancy , Benzel Isabel , Kew James N. C. , Harrison Paul J. , Burnet Philip W. J.
Published: September 2007

The N‐methyl‐d‐aspartate receptor co‐agonist d‐serine is synthesized by serine racemase and degraded by d‐amino acid oxidase. Both d‐serine and its metabolizing enzymes are implicated in N‐methyl‐d‐aspartate receptor hypofunction thought to occur in schizophrenia. We studied d‐amino acid oxidase and serine racemase immunohistochemically in several brain regions and compared their immunoreactivity and their mRNA levels in the cerebellum and dorsolateral prefrontal cortex in schizophrenia. d‐Amino acid oxidase immunoreactivity was abundant in glia, especially Bergmann glia, of the cerebellum, whereas in prefrontal cortex, hippocampus and substantia nigra, it was predominantly neuronal. Serine racemase was principally glial in all regions examined and demonstrated prominent white matter staining. In schizophrenia, d‐amino acid oxidase mRNA was increased in the cerebellum, and as a trend for protein. Serine racemase was increased in schizophrenia in the dorsolateral prefrontal cortex but not in cerebellum, while serine racemase mRNA was unchanged in both regions. Administration of haloperidol to rats did not significantly affect serine racemase or d‐amino acid oxidase levels. These findings establish the major cell types wherein serine racemase and d‐amino acid oxidase are expressed in human brain and provide some support for aberrant d‐serine metabolism in schizophrenia. However, they raise further questions as to the roles of d‐amino acid oxidase and serine racemase in both physiological and pathophysiological processes in the brain.
Late emergence of synchronized oscillatory activity in the pallidum during progressive parkinsonism
Authors: Leblois Arthur , Meissner Wassilios , Bioulac Bernard , Gross Christian E. , Hansel David , Boraud Thomas
Published: September 2007

Parkinson's disease is known to result from basal ganglia dysfunction. Electrophysiological recordings in parkinsonian patients and animals have shown the emergence of abnormal synchronous oscillatory activity in the cortico‐basal ganglia network in the pathological condition. In addition, previous studies pointed out an altered response pattern during movement execution in the pallidum of parkinsonian animals. To investigate the dynamics of these changes during disease progression and to relate them to the onset of the motor symptoms, we recorded spontaneous and movement‐related neuronal activity in the internal pallidum of nonhuman primates during a progressive dopamine depletion process. Parkinsonian motor symptoms appeared progressively during the intoxication protocol, at the end of which both animals displayed severe akinesia, rigidity and postural abnormalities. Spontaneous firing rates did not vary significantly after intoxication. During the early phase of the protocol, voluntary movements were significantly slowed down and delayed. At the same time, the neuronal response to movement execution was modified and inhibitory responses disappeared. In contrast, the unitary and collective dynamic properties of spontaneous neuronal activity, as revealed by spectral and correlation analysis, remained unchanged during this period. Spontaneous correlated activity increased later, after animals became severely bradykinetic, whereas synchronous oscillatory activity appeared only after major motor symptoms developed. Thus, a causality between the emergence of synchronous oscillations in the pallidum and main parkinsonian motor symptoms seems unlikely. The pathological disruption of movement‐related activity in the basal ganglia appears to be a better correlate at least to bradykinesia and stands as the best candidate to account for this motor symptom.
Muscarinic blockade weakens interaction of gamma with theta rhythms in mouse hippocampus
Authors: Hentschke Harald , Perkins Mark G. , Pearce Robert A. , Banks Matthew I.
Published: September 2007

θ (4–12 Hz) and γ (40–90) oscillations are prominent rhythms in the mammalian brain. A striking feature of these rhythms, possibly vital to memory encoding, is their specific coordination in a manner that has been termed ‘nesting’, i.e. the preferred occurrence of bouts of γ activity during specific phases of θ. Both rhythms are shaped by the neuromodulator acetylcholine, but it is unknown to what degree their coordination is influenced by cholinergic neuromodulation. Here, we investigated the effects of a blockade of muscarinic acetylcholine receptors by atropine on θ and γ oscillations, and their interaction, in mouse hippocampus in vivo. Multi‐site recordings from area CA1 of freely moving mice showed that under control conditions γ activity was amplitude‐modulated at θ frequencies. This coordination of θ and γ oscillations, as assessed by cross‐correlation of θ with the γ envelope, was prominent in basal and apical dendritic laminae but not in intermediate laminae. It was stronger during active exploration than during awake immobility. Atropine (50 mg/kg intraperitoneal) altered several aspects of the individual and nested rhythms. It rendered θ activity irregular, decreased θ oscillation frequency and reduced γ power. Atropine also reduced the amplitude‐modulation of γ oscillations at θ frequencies, in part by perturbing the coordination of the rhythms on a short time scale. Thus, our findings demonstrate that phase locking of the amplitude of γ oscillations to θ in hippocampal area CA1 is partially governed by neuronal elements harbouring muscarinic receptors.
The DPP‐4 inhibitor vildagliptin: robust glycaemic control in type 2 diabetes and beyond
Authors: Panina G.
Published: September 2007

Vildagliptin is a potent selective inhibitor of dipeptidyl peptidase‐4 (DPP‐4) that improves glycaemic control by increasing islet α‐cell and β‐cell responsiveness to glucose. In patients with type 2 diabetes mellitus (T2DM), vildagliptin improves β‐cell function, measured as insulin secretory rate relative to glucose level, and reduces glucagon secretion and endogenous glucose production in the postprandial period, resulting in reduced glucose levels. In clinical trials in T2DM, vildagliptin 100 mg/day monotherapy is effective in reducing haemoglobin A1c (HbA1c) across the spectrum of hyperglycaemia and has maintained efficacy over long‐term treatment with neutral effects on body weight and lipids. Vildagliptin is associated with a low risk of hypoglycaemia, and has an adverse event profile comparable to placebo, including a reduced rate of gastrointestinal adverse effects compared with metformin and a reduced rate of oedema compared with rosiglitazone. As add‐on combination therapy, vildagliptin produces significant further reductions in HbA1c in patients receiving metformin, pioglitazone, glimepiride and insulin, and has been found to reduce frequency of hypoglycaemia as an add‐on to insulin. Preliminary findings indicate that the improved islet cell function underlying the efficacy of vildagliptin in T2DM is also observed in patients with impaired glucose tolerance, with vildagliptin treatment resulting in reduced glycaemic excursions. The overall profile of vildagliptin and the preliminary evidence of beneficial effects in the prediabetic state suggest that DPP‐4 inhibition could be an effective strategy to prevent or delay progression from the prediabetic state to overt T2DM.
Surveillance, Spatial Compression, and Scale: The FBI and Martin Luther King Jr
Authors: Boykoff Jules
Published: September 2007

Abstract: In 1976, the Church Committee, a Senate Select Committee to Study Governmental Operations, came to the conclusion that Martin Luther King Jr “was the target of an intensive campaign by the Federal Bureau of Investigation to ‘neutralize’ him as an effective civil rights leader”. This paper explores how the FBI surveilled Martin Luther King Jr between September 1957 and Dr King's death in 1968 and how such surveillance relates to both spatial compression and scale. First, using FBI internal memos, government documents, social movement archives, mass‐media accounts, and other sources, I reconstruct this history of state surveillance, partitioning it into three sequential phases. Then, I shift from description to analysis, exploring how surveillance—operating through the social mechanism of intimidation—compressed both the physical and tactical space that Dr King and the Southern Christian Leadership Conference could comfortably inhabit. This paper also theorizes the relationship between state surveillance and scale within the larger process of state suppression of dissent since scale both demarcates the boundaries where socio‐political contestation occurs and also plays an important role in how these contests play out.
The Role of Environmental Factors in the Causation of Sudden Death in Infants: Two Cases of Sudden Unexpected Death in Two Unrelated Infants Who Were Cared for by the Same Babysitter
Authors: Omalu Bennet I. , Lindner Jennifer L. , Janssen Jennifer K. , Nnebe‐Agumadu Uche , Weedn Victor
Published: September 2007

Abstract:  We report two cases of sudden unexpected death in two unrelated African American female infants, 2 months and 4 months old. Both infants were attended to by the same babysitter in the same apartment and died 39 days apart in the same bed and in the same bedroom. The autopsy of the first infant revealed sudden unexplained death in an infant. Toxicologic analysis for carbon monoxide (CO) was not performed because it was not suspected. When the second infant died, investigation into the ambient air quality within the apartment revealed high levels of CO emanating from a poorly ventilated and defective hot water heater, which was located across a hallway from the bedroom where the two babies died. CO saturation levels in the postmortem blood samples of the two babies were elevated and were similar (13% and 14%). Nicotine and cotinine were not detected in the blood sample of the two infants. Cherry‐red livor mortis was absent. Acute CO intoxication was determined to be the underlying cause of these two unexpected deaths. These two cases underscore the need to integrate ambient air analysis and postmortem CO analysis as routine components of the comprehensive death investigation of infants who die suddenly and unexpectedly.
Mistaken identity of skin cleansing solution leading to extensive chemical burns in an extremely preterm infant
Authors: Mannan K , Chow P , Lissauer T , Godambe S
Published: September 2007

Chemical burns in extremely preterm infants have major implications in terms of morbidity and risk management. We report a case of extensive chemical burn in an extremely low birth weight (ELBW) infant caused by clear, colourless solution of 0.5% chlorhexidine in 70% alcohol mistaken for normal saline for skin cleansing during umbilical catheter insertion. This case reflects the on going problem faced by many neonatal intensive care units of similar coloured solutions with similar packages, but with varying degrees of toxic effects.

Conclusion: The case highlights the importance of having a clear policy for skin cleansing in every neonatal unit and measures to avoid errors by vigilant checking of all medications including topical solutions.
National registry diagnoses agree with medical records on hospitalized asthmatic children
Authors: Moth Grete , Vedsted Peter , Schiøtz PO
Published: September 2007

Aim: The present study was performed to explore the validity of discharge diagnoses on asthma in the Danish National Patient Registry compared with medical records.

Methods: A review of medical records on all acute hospital admissions of 6–14‐year‐old children in 10 Danish hospitals between July and December 2002 was conducted. The personal registration number and dates on admissions due to asthma were sent to the Danish National Patient Registry for information on discharge diagnoses, and admission and discharge dates. Agreement between medical records and the Danish National Patient Registry was sought by sensitivity, specificity, and the positive and negative predictive value.

Results: Medical records of 3550 children aged 6–14 years were reviewed. A total of 300 admissions were due to asthma, 271 of which were also registered with an asthma diagnosis unit in the Danish National Patient Registry. Collection of data in the Danish National Patient Registry showed a surplus of 49 admissions due to asthma compared to hospital record data. The sensitivity of an asthma diagnosis in the registry then was 0.90, specificity 0.99, positive predictive value 0.85 and negative predictive value 0.99.

Conclusions: Data on paediatric asthma diagnoses in the Danish National Patient Registry are valid and may serve as useful tools in research.
Grass‐Shrub Riparian Buffer Removal of Sediment, Phosphorus, and Nitrogen From Simulated Runoff1
Authors: Mankin Kyle R. , Ngandu Daniel M. , Barden Charles J. , Hutchinson Stacy L. , Geyer Wayne A.
Published: September 2007

Abstract: Riparian buffer forests and vegetative filter strips are widely recommended for improving surface water quality, but grass‐shrub riparian buffer system (RBSs) are less well studied. The objective of this study was to assess the influence of buffer width and vegetation type on the key processes and overall reductions of total suspended solids (TSS), phosphorus (P), and nitrogen (N) from simulated runoff passed through established (7‐year old) RBSs. Nine 1‐m RBS plots, with three replicates of three vegetation types (all natural selection grasses, two‐segment buffer with native grasses and plum shrub, and two‐segment buffer with natural selection grasses and plum shrub) and widths ranging from 8.3 to 16.1 m, received simulated runoff having 4,433 mg/l TSS from on‐site soil, 1.6 mg/l total P, and 20 mg/l total N. Flow‐weighted samples were collected by using Runoff Sampling System (ROSS) units. The buffers were very efficient in removal of sediments, N, and P, with removal efficiencies strongly linked to infiltration. Mass and concentration reductions averaged 99.7% and 97.9% for TSS, 91.8% and 42.9% for total P, and 92.1% and 44.4% for total N. Infiltration alone could account for >75% of TSS removal, >90% of total P removal, and >90% of total N removal. Vegetation type induced significant differences in removal of TSS, total P, and total N. These results demonstrate that adequately designed and implemented grass‐shrub buffers with widths of only 8 m provide for water quality improvement, particularly if adequate infiltration is achieved.
Conflicting Requirements of
Plasmodium falciparum
Dihydrofolate Reductase Mutations Conferring Resistance to Pyrimethamine-WR99210 Combination
Authors: Japrung Deanpen , Leartsakulpanich Ubolsree , Chusacultanachai Sudsanguan , Yuthavong Yongyuth
Published: September 2007

Plasmodium falciparum
strains bearing quadruple mutations of dihydrofolate reductase-thymidylate synthase (PfDHFR-TS) at codons 51, 59, 108, and 164 are highly resistant to pyrimethamine (PYR), a diaminopyrimidine, but sensitive to WR99210 (WR), a cycloguanil analog, suggesting different enzyme-inhibitor binding interactions. A combination of these inhibitors to delay the onset of antifolate resistance is proposed. Using error-prone PCR, libraries of random mutants of wild-type PfDHFR and PfDHFR-TS were generated and used to transform
Escherichia coli
, and transformants were then selected for PYR or WR resistance. Mutants highly resistant to either PYR or WR were also generated from libraries obtained from further random mutagenesis of quadruple mutants (QM) with mutations in PfDHFR or PfDHFR-TS. For reversion mutants carrying altered residues I51N, N108S, and L164I, a further mutation of D54N was required to achieve resistance against WR, but these mutants regained sensitivity to PYR. When a combination of PYR and WR was used, fewer resistant mutants were generated from both mutant libraries using the QM gene templates. The effectiveness of the drug combination in reducing the appearance of resistance mutations is likely due to conflicting requirements for mutations conferring resistance to the two drugs. Thus, a combination of inhibitors from these two drug classes should be effective in impeding the emergence of
P. falciparum
resistance to antifolates.
Capability of 11 Antipneumococcal Antibiotics To Select for Resistance by Multistep and Single-Step Methodologies
Authors: Clark Catherine L. , Kosowska-Shick Klaudia , Ednie Lois M. , Appelbaum Peter C.
Published: September 2007

Testing of 12 pneumococcal strains with differing resistotypes [including
tet
(M) positive] showed that tigecycline, amoxicillin-clavulanate, imipenem, and ceftriaxone did not select for resistant clones after 50 sequential subcultures. By comparison, azithromycin, clarithromycin, clindamycin, telithromycin, levofloxacin, moxifloxacin, and gemifloxacin did show resistant clones. Tigecycline also yielded a low frequency of resistance in single-step tests compared to all β-lactams, macrolides/ketolides, and quinolones tested.
Toll-Like Receptor 2 Regulates CXC Chemokine Production and Neutrophil Recruitment to the Cornea inOnchocerca volvulus/Wolbachia-Induced Keratitis
Authors: Gillette-Ferguson Illona , Daehnel Katrin , Hise Amy G. , Sun Yan , Carlson Eric , Diaconu Eugenia , McGarry Helen F. , Taylor Mark J. , Pearlman Eric
Published: September 2007

The filarial nematodeOnchocerca volvulusis the causative organism of river blindness. Our previous studies demonstrated an essential role for endosymbioticWolbachiabacteria in corneal disease, which is characterized by neutrophil infiltration into the corneal stroma and the development of corneal haze. To determine the role of Toll-like receptors (TLRs) in neutrophil recruitment and activation, we injected a soluble extract ofO. volvuluscontainingWolbachiabacteria into the corneal stromata of C57BL/6, TLR2−/−, TLR4−/−, TLR2/4−/−, and TLR9−/−mice. We found an essential role for TLR2, but not TLR4 or TLR9, in neutrophil recruitment to the cornea and development of corneal haze. Furthermore, chimeric mouse bone marrow studies showed that resident bone marrow-derived cells in the cornea can initiate this response. TLR2 expression was also essential for CXC chemokine production by resident cells in the cornea, including corneal fibroblasts, and for neutrophil activation. Taken together, these findings indicate thatWolbachiaactivates TLR2 on resident bone marrow-derived cells in the corneal stroma to produce CXC chemokines, leading to neutrophil recruitment to the corneal stroma, and that TLR2 mediatesO. volvulus/Wolbachia-induced neutrophil activation and development of corneal haze.
An Approach for Self‐Checking Realization ofInteracting Finite State Machines
Authors: Busaba Fadi , Lala Parag K.
Published: September 2007

This paper presents a technique for designing interacting finite state machines which will be totally self‐checking
for any single stuck‐at fault. In the proposed technique m‐out‐of‐n codes are used for both primary output and
state assignments. In addition, the next state logic (NSL) for each submachine and the output logic (OL) are
realized such that any single stuck‐at fault results in either single bit error or unidirectional multibit error at the
output. The proposed technique does not have any restriction on the way the NSL and the OL are implemented.
A Comparative Study of SynchronousClocking Schemes for VLSI Based Systems
Authors: El-Amawy Ahmed , Maheshwar Umasankar
Published: September 2007

Recently a novel clock distribution scheme called Branch‐and‐Combine(BaC) has been proposed. The scheme
guarantees constant skew bound irrespective of the size of the clocked network. It utilizes simple nodes to process
clock signals such that clock paths are adaptively selected to guarantee constant skew bound. The paper uses a
VLSI model to compare the properties of the new scheme to those of the well established H‐Tree approach. The
H‐Tree is a binary tree of simple buffers which is laid out such that leaves are at equal distances from the root.
Our study considers clocking 2‐D processor meshes of arbitrary sizes. We evaluate and compare the relevant
parameters of both schemes in a VLSI layout context. We utilize parameters such as clock skew, link costs, node
costs and area efficiency as the basis for comparison. We show that for each BaC network, there is a certain
threshold size after which it outperforms the corresponding tree network in terms of skew. We also show that
except for node costs, BaC networks outperform the H‐Tree, especially when the size of the clocked network is
large. As an extension we show that BaC clocking does not suffer from potential pulse disappearance, no matter
how large the network is.
Applying Neural Networks to Findthe Minimum Cost Coverageof a Boolean Function
Authors: Chu Pong P.
Published: September 2007

To find a minimal expression of a boolean function includes a step to select the minimum cost cover from a set of
implicants. Since the selection process is an NP‐complete problem, to find an optimal solution is impractical for
large input data size. Neural network approach is used to solve this problem. We first formalize the problem, and
then define an “energy function” and map it to a modified Hopfield network, which will automatically search for
the minima. Simulation of simple examples shows the proposed neural network can obtain good solutions most of
the time.
2‐D Simulation of Quantum Effects in SmallSemiconductor Devices Using QuantumHydrodynamic Equations
Authors: Zhou Jing-Rong , Ferry David K.
Published: September 2007

We discuss the basis of a set of quantum hydrodynamic equations and the use of this set of equations in the
two‐dimensional simulation of quantum effects in deep submicron semiconductor devices. The equations are
obtained from the Wigner function equation‐of‐motion. Explicit quantum correction is built into these equations
by using the quantum mechanical expression of the moments of the Wigner function, and its physical implication
is clearly explained. These equations are then applied to numerical simulation of various small semiconductor
devices, which demonstrate expected quantum effects, such as barrier penetration and repulsion. These effects
modify the electron density distribution and current density distribution, and consequently cause a change of the
total current flow by 10‐15 per cent for the simulated HEMT devices. Our work suggests that the inclusion of
quantum effects into the simulation of deep submicron and ultra‐submicron semiconductor devices is necessary.
A Modified Approach to Test Plan Generation for Combinational Logic Blocks
Authors: Basu Anupam , Banerji Dilip K. , Basu Amit , Wilson T. C. , Majithia Jay C.
Published: September 2007

Generation of test plans is a crucial step for testing VLSI circuits. This paper presents a modified approach to test plan generation for the BILBO test methodology. A few limitations of the existing approaches have been identified and methods to address these have been suggested. The proposed approach has been implemented for the general case of n‐port combinational logic blocks (CLBs). However, due to limitations of space and for clarity,
only 2‐port CLBs are considered in this paper. For this case, the problem is modelled as a Step Scheduling Matrix and an algorithm is presented for the solution. The algorithm has been tested on a number of benchmark circuits and the results are compared with those obtained through existing methods. The effectiveness of the proposed approach is clear from the results, as it contributes to the reduction in total testing time as well as generates a larger
number of test plans.
Segmented Routing for Speed‐Performance and Routability in Field‐Programmable Gate Arrays
Authors: Brown Stephen , Khellah Muhammad , Lemieux Guy
Published: September 2007

This paper addresses several issues involved for routing in Field‐Programmable Gate Arrays (FPGAs) that have both horizontal and vertical routing channels, with wire segments of various lengths. Routing is studied by using CAD routing tools to map a set of benchmark circuits into FPGAs, and measuring the effects that various parameters of the CAD tools have on the implementation of the circuits. A two‐stage routing strategy of global followed by detailed routing is used, and the effects of both of these CAD stages are discussed, with emphasis on detailed routing. We present a new detailed routing algorithm designed specifically for the types of routing structures found in the most recent generation of FPGAs, and show that the new algorithm achieves significantly better results than previously published FPGA routers with respect to the speed‐performance of implemented circuits.

The experiments presented in this paper address both of the key metrics for FPGA routing tools, namely the effective utilization of available interconnect resources in an FPGA, and the speed‐performance of implemented circuits. The major contributions of this research include the following: 1) we illustrate the effect of a global router on both area‐utilization and speed‐performance of implemented circuits, 2) experiments quantify the impact of the
detailed router cost functions on area‐utilization and speed‐performance, 3) we show the effect on circuit implementation of dividing multi‐point nets in a circuit being routed into point‐to‐point connections, and 4) the paper illustrates that CAD routing tools should account for both routability and speed‐performance at the same time, not just focus on one goal.
HYSIM: Hybrid Fault Simulation for Synchronous Sequential Circuits
Authors: Kim Kyuchull , Saluja Kewal K.
Published: September 2007

The paper identifies the inefficiencies of the critical processes in concurrent fault simulation and proposes methods to remove such inefficiencies in a systematic manner. Also, proposed are dynamic memory usage reduction strategies for concurrent fault simulators. Through extensive step‐by‐step experimentation, we verified the effectiveness of the proposed methods for performance improvement and identified best memory management strategy for dynamic memory usage reduction. A simulator, HySim, based on the proposed methods is implemented and shown to outperform the existing fault simulators and achieve dramatic memory usage reduction. The HySim maintains fault lists which are subsets of that of a conventional concurrent fault simulator, which yields shorter fault list processing time and reduced dynamic memory usage. It also employs Release‐and‐Reconstruct method for fault list construction, where any fault list identified to be useless is released immediately. The experimental results show that Release‐and‐Reconstruct method is very effective in dynamic memory usage reduction.
Behavioral Simulation and Performance Evaluation of Multi‐Processor Architectures
Authors: Mahmood Ausif
Published: September 2007

The development of multi‐processor architectures requires extensive behavioral simulations to verify the correctness of design and to evaluate its performance. A high level language can provide maximum flexibility in this respect if the constructs for handling concurrent processes and a time mapping mechanism are added. This paper describes a novel technique for emulating hardware processes involved in a parallel architecture such that an object‐oriented description of the design is maintained. The communication and synchronization between hardware processes is handled by splitting the processes into their equivalent subprograms at the entry points. The proper scheduling of these subprograms is coordinated by a timing wheel which provides a time mapping mechanism. Finally, a high level language pre‐processor is proposed so that the timing wheel and the process emulation details can be made transparent to the user.
Hierarchical Process Simulation for Nano‐Electronics
Authors: Dutton Robert W. , Kan Edwin C.
Published: September 2007

The challenges of computational electronics are considered from the perspective of process
simulation. Essential limitations for device scaling posed from a technology point of view are
discussed along with many new research opportunities. The key areas considered include:
bulk processing, interconnect technology and software engineering for computational electronics.
One‐Dimensional Analysis of Subthreshold Characteristics of SOI‐MOSFET ConsideringQuantum Mechanical Effects
Authors: Ikeno Rimon , Ito Hiroshi , Asada Kunihiro
Published: September 2007

We have been studying on subthreshold characteristics of SOI MOSFETs in terms of substrate
bias dependence, using a 1‐D Poisson equation on an SOI multi‐layer structure for estimating
structural parameters of real devices[1]. Here, we consider quantum mechanical
effects in the electron inversion layer of thin SOI MOSFETs, implementing a self‐consistent
solver of Poisson and Schrödinger equations in a 1‐D subthreshold simulator. From results of
simulations, we have concluded that quantum mechanical effects need to be considered in
analizing thin SOI devices.
Numerically Absorbing Boundary Conditions for Quantum Evolution Equations
Authors: Arnold Anton
Published: September 2007

Transparent boundary conditions for the transient Schrödinger equation on a domain Ω can be
derived explicitly under the assumption that the given potential V is constant outside of this
domain. In 1D these boundary conditions are non‐local in time (of memory type). For the
Crank‐Nicolson finite difference scheme, discrete transparent boundary conditions are
derived, and the resulting scheme is proved to be unconditionally stable. A numerical example
illustrates the superiority of discrete transparent boundary conditions over existing ad‐hoc
discretizations of the differential transparent boundary conditions.
As an application of these boundary conditions to the modeling of quantum devices, a transient
1D scattering model for mixed quantum states is presented.
A New Approach based on Brownian Motion for theSimulation of Ultra‐Small Semiconductor Devices
Authors: Arokianathan Clinton R. , Asenov Asen , Davies John H.
Published: September 2007

We present a new approach to the simulation of ultra‐small semiconductor devices based on
Brownian motion of the carriers described by the Langevin equation. It follows the trajectories
of individual particles in real space but does not require the computational effort of a full
Monte Carlo simulation. This method is particulary useful for modeling very small devices
where individual impurities and carries must be considered as discrete entities, and where a
molecular dynamics approach is used in a full‐scale three‐dimensional simulation. We show
that this method gives the correct Maxwell‐Boltzmann distribution and that it provides a good
description of transport through a short diode.
Gain Calculation in a Quantum Well Laser SimulatorUsing an Eight Band k.p Model
Authors: Oyafuso F. , von Allmen P. , Grupen M. , Hess K.
Published: September 2007

Effects of non‐parabolicity and band‐warping of the energy dispersion are entered in a quantum
well laser simulator (MINILASE‐II), which self‐consistently solves Schödinger′s equation,
Poisson′s equation, the drift diffusion equations, and the photon rate equations. An eight
band k.p model is used to determine the electronic band structure for a strained‐layer
In.2Ga.8As/Al.1Ga.9As system. The k.p calculation is performed independently of the laser
simulator, and exported to MINILASE‐II in the form of a density of states and an energydependent
averaged momentum matrix element. The results obtained for the gain and modulation
response are compared to those obtained from a parabolic band model with a constant
matrix element.
Second Order Newton Iteration Methodand Its Application to MOS Compact Modelingand Circuit Simulation
Authors: Yu Zhiping , Dutton Robert W.
Published: September 2007

A robust second order Newton iteration scheme is proposed for solving the nonlinear algebraic
equations. Potential applications include the projection of the initial guess to the solution
when the parameters in the equations are changed. The mathematical derivation leading
to the scheme is given and pros and cons of the method are discussed. As an example, the
method has been applied to the evaluation of charge‐sheet model for MOS as used in the circuit
simulation.
A Monte Carlo Study of Electron Transport in Silicon nMOSFET Inversion Layers
Authors: Shih W.-K. , Jallepalli S. , Yeap C.-F. , Rashed M. , Maziar C. M. , Tasch A. F.
Published: September 2007

Monte Carlo simulations of uniform silicon nMOSFET inversion layers have been performed.
Excellent agreement between the simulated and experimental transport characteristics
has been observed in the region of strong inversion at both 300K and 77K. The
contribution to the effective mobility due to individual subbands has been analyzed and qualitatively
explained.
Clustering Network Modules with Different Implementations for Delay Minimization
Authors: Karayiannis Dimitrios , Tragoudas Spyros
Published: September 2007

In recent years there has been an extensive interest in clustering the modules of a
network so that the maximum delay from any primary input to any primary output is
minimized [8, 7, 6]. Clusters have a maximum capacity and modules may have different
implementations. All existing CAD frameworks initially select an implementation of
each module, and at a later stage they cluster the modules. We present an approach that
clusters the nodes, while considering their alternative implementations, so that we
further minimize the maximum delay after the clustering. Our approach is based on
optimal algorithms for restricted versions of this complex problem in circuit design, and
outperforms the conventional approach, which first obtains an implementation for each
circuit module without considering clustering and then, in a later step, performs
clustering.
Observation of Anomalous Negative DifferentialResistance in Diode Breakdown Simulation Using CarrierTemperature Dependent Impact Ionization
Authors: Kan Edwin C. , Jin Gyoyoung , Yu Zhiping , Dutton Robert W.
Published: September 2007

When carrier temperatures are used to model impact ionization with self‐consistent cooling
effects, anomalous negative differential resistance (NDR) was found in diode breakdown
simulation. Possible mechanisms responsible for the NDR are analyzed.
Simulated Annealing Approach to Crosstalk Minimization in Gridded Channel Routing
Authors: Jhang Kyoung-Son , Ha Soonhoi , Jhon Chu Shik
Published: September 2007

The inter‐wire spacing in a VLSI chip becomes closer as the VLSI fabrication
technology rapidly evolves. Accordingly, it becomes important to minimize crosstalk
caused by the coupling capacitance between adjacent wires in the layout design for the
fast and safe VLSI circuits. We present a simulated annealing approach based on
segment rearrangement to crosstalk minimization in an initially gridded channel
routing. The proposed technique is compared with previous track‐oriented techniques,
especially a track permutation technique whose performance is bounded by an
exhaustive track permutation algorithm. Experiments showed that the presented
technique is more effective than the track permutation technique.
Topologically Rectangular Grids in the Parallel Simulationof Semiconductor Devices
Authors: Asenov A. , Brown A. R. , Roy S. , Barker J. R.
Published: September 2007

Topologically rectangular grids offer simplicity and efficiency in the design of parallel semiconductor
device simulators tailored for mesh connected MIMD platforms. This paper
presents several approaches to the generation of topologically rectangular 2D and 3D grids.
The effects of the partitioning of such grids on different processor configurations are studied.
A simulated annealing algorithm is used to optimise the partitioning of 2D and 3D grids on
two dimensional arrays of processors. Problems related to the discretization, parallel matrix
generation and solution strategy are discussed. The use of topologically rectangular grids is
illustrated through the example of power electronic device simulation.
The Quantum Hydrodynamic Smooth Effective Potential
Authors: Gardner Carl L. , Ringhofer Christian
Published: September 2007

An extension of the quantum hydrodynamic (QHD) model is discussed which is valid for
classical potentials with discontinuities. The effective stress tensor for the QHD equations
cancels the leading singularity in the classical potential at a barrier and leaves a residual
smooth effective potential with a lower potential height in the barrier region. The smoothing
makes the barrier partially transparent to the particle flow and provides the mechanism for
particle tunneling in the QHD model.
A New Concept for Solving the Boltzmann TransportEquation in Ultra‐fast Transient Situations
Authors: Cheng Ming-C.
Published: September 2007

A concept based on relaxation of the hydrodynamic parameters is introduced to arrive at a
computational model for the extreme non‐equilibrium distribution function of carriers in
multi‐valley bandstructure. The relaxation times are taken to describe the evolution scale of
the distribution function. The developed model is able to account for transport phenomena at
the momentum relaxation scale. The model, together with the Monte Carlo simulation, is
applied to obtain the electron distribution function in each valley of the lower conduction
band in GaAs, and to study the evolution of the distribution function in GaAs subjected to
rapid changes in field.
Corrections to the Capacitance between Two ElectrodesDue to the Presence of Quantum Confined System
Authors: Macucci M. , Hess K.
Published: September 2007

We have studied the capacitance between two parallel plates enclosing a quantum confined
system and its dependence on the applied voltage. The concepts of capacitance and differential
capacitance are discussed together with their applicability to systems characterized by
single.electron tunneling. We determine the tunneling thresholds by means of a formalism
based on the minimization of the system free energy and we retrieve, as a special case,
Luryi′s quantum capacitance formula. We apply our method to the study of an idealized system
made up of a number of quantum dots with random size distributed according to a gaussian.
Results are shown for different choices of the position of the dots between the plates and
of the voltage span applied to perform the measurement of the differential capacitance.
An Efficient Solution Scheme for the Spherical‐HarmonicsExpansion of the Boltzmann Transport Equation Appliedto Two‐Dimensional Devices
Authors: Vecchi Maria Cristina , Mohring Jan , Rudan Massimo
Published: September 2007

This paper presents a novel numerical scheme applicable to the solution of the Boltzmann
transport equation by means of a spherical‐harmonics expansion. This scheme improves the
solution at low energies, keeping the desired accuracy in the calculation of the mean quantities
while saving a significant amount of CPU time. This is important in view of the applications
of the method, since the typical number of nodes to be used in the combined
space‐energy domain is in the range of 104‐105.
2D Finite Element Method Simulation of Lateral Resonant Tunneling Devices
Authors: Shao Zhi-An , Porod Wolfgang , Lent Craig S.
Published: September 2007

Using the finite element method, we investigate device applications of lateral resonant tunneling
structures which consist of a transmission channel with attached resonators. Such
structure exhibits resonance‐antiresonance transmission features which may be engineered to
achieve desired device properties.
We show that the valley current can be reduced in such 2D lateral resonant tunneling
devices, resulting in an improved current peak‐to‐valley ratio.
Sorting on Reconfigurable Meshes:An Irregular Decomposition Approach
Authors: Lai Ten H. , Sheng Ming-Jye
Published: September 2007

Most algorithms for reconfigurable meshes (R‐meshes) are based on the divide‐and‐conquer
(DAC) strategy. Although the strategy per se does not require the subproblems
to be equal in size, existing DAC algorithms for R‐meshes do divide the problem
approximately evenly. This paper demonstrates that dividing a problem evenly is not
necessarily a good way to decompose a problem. There are occasions on which an
irregular decomposition scheme may be preferable. We take this approach and obtain a
new sorting algorithm. Our sorting algorithm has several strengths: it is simple, scalable,
and as broadcast‐efficient as the best known result.
Investigation of Various Mesh ArchitecturesWith Broadcast Buses for High‐Performance Computing
Authors: Ziavras Sotirios G.
Published: September 2007

Extensive comparative analysis is carried out of various mesh‐connected architectures
that contain sparse broadcast buses for low‐cost, high‐performance parallel computing.
The two basic architectures differ in the implementation of bus intersections. The first
architecture simply allows row/column bus crossovers, whereas the second architecture
implements such intersections with switches that introduce further flexibility. Both
architectures have lower cost than the mesh with multiple broadcast, which has buses
spanning each row and each column, but the former architectures maintain to high
extent the powerful properties of the latter mesh. The architecture that employs switches
for the creation of separable buses is even shown to often perform better than the
higher‐cost mesh with multiple broadcast. Architectures with separable buses that
employ store‐and‐forward routing often perform better than architectures with
contiguous buses that employ the high‐cost wormhole routing technique. These
architectures are evaluated in reference to cost, and efficiency in implementing several
important operations and application algorithms. The results prove that these
architectures are very promising alternatives to the mesh with multiple broadcast while
their implementation is cost‐effective and feasible.
Placement with Incomplete Data
Authors: Wang Maogang , Banerjee Prithviraj , Sarrafzadeh Majid
Published: September 2007

Traditional placement problems are studied under a fully specified cell library and a
complete netlist. However, in the first, e.g., 2 years of a 2 – 3 year microprocessor design
cycle, the detailed netlist is unavailable. For area and performance estimation, layout
must nevertheless be done with incomplete information. Another source of incompleteness
comes from logic synthesis changes; some instances and their parameters will change
as the project evolves. In the re‐configurable computing area, sometimes we need to
perform quick placement before all information is available. The problem of placement
with incomplete data (PID) can be abstracted as having to place a circuit when pc% of the cells and pn% of the nets are missing. The key challenge in PID is how to add missing
cells and nets.

In this paper, two “patching‐methods” for adding missing nets and cells are proposed.
The methods are called abstraction and fusion.

Experimental results are very interesting. First, they show that PID is a difficult problem
and an arbitrary (and perhaps intuitively sound) method may not produce highquality
results. Experiments verify that the abstraction method is a very good predictor
and that fusion is not. Specifically, when a circuit has 10% incompleteness, abstraction
can predict the final total wirelength with an error of 5.8% while fusion has a 67.8% error
in predicting the wirelength in the same circuit.
Memory Chips with Adjustable Configurations
Authors: John Lizy Kurian
Published: September 2007

In this paper, we present the concept of Field Programmable Memory Cell Arrays
(FPMCAs) as the memory counterpart to Field Programmable Gate Arrays which have
proved their utility in design and rapid prototyping. Principles of dynamic reconfigurability
using programmable logic and programmable interconnect are incorporated into
random access memories to achieve this flexibility. We first present the design of a
variable width RAM (VaWiRAM) which is a simple example of a Field Programmable
Memory Cell Array. The configuration of VaWiRAMs can be adjusted by setting a few
configuration pins on the memory chip. A VaWiRAM reconfigurable between widths 1 and Wmax⁡ can be constructed with the extra cost of Wmax⁡ – 1 pass gates, (Wmax⁡/2) 2‐to‐1
multiplexers, and ⌈log⁡2[log⁡2(k)  +  1]⌉
mode pins. A novel scheme to overlap the address
pins with mode control pins and achieve the mode control with only one extra pin is also
presented. The paper discusses the architecture of the proposed VaWiRAMs in detail,
analyzes the design tradeoffs and introduces the concept of FPMCAs.
Inflow Boundary Conditions in Quantum Transport Theory
Authors: Lange Horst , Toomire Bruce , Zweifel P. F.
Published: September 2007

A linear (given potential) steady‐state Wigner equation is considered in conjunction
with inflow boundary conditions and relaxation‐time terms. A brief review of the use of
inflow conditions in the classical case is also discussed. An analytic expansion of
solutions is shown and a recursion relation derived for the given problem under certain
regularity assumptions on the given inflow data. The uniqueness of the physical current
of the solutions is shown and a brief discussion of the lack of charge conservation
associated with the relaxation‐time is given.
A New Bus Assignment Algorithm for a Shared Bus Switch Fabric
Authors: Torres D. , Gonzalez J. , Guzman M.
Published: September 2007

An architecture for a Cell Switch Fabric (CSF) with a new bus assignment strategy is
presented. The proposed architecture has a modular structure with a chip partitioning
oriented to avoid the system from falling down totally, thus achieving expandability and
increasing reusability. A discussion about different algorithms for the bus assignment
is given. The shared bus is assigned in a cyclic and rotative way, switching microcells
instead of cells. The CSF is built in four PCBs where every one has a capacity for four
ports at 164.323 Mbps, the external port rate is 155.52 Mbps. A microcontroller realizes
some tests and communicates with a PC, which runs a test, verification and CSF
configuration program. Some parameters about the CSF behavior are measured too.
Each Port was implemented on a CPLD FLEX10K100 and the Switch Control Block
on a circuit MAX7128, both from Altera Company.
Graphical Design Techniques for Fixed‐point Multiplication
Authors: Dempster A. G.
Published: September 2007

This is a tutorial paper that examines the problem of performing fixed‐point constant
integer multiplications using as few adders as possible. The driving application is the
design of digital filters, where it is often required that several products of a single
multiplicand are produced. Thus two specific problems are examined in detail, i.e.,
the one‐input/one‐output case and the one‐input/several‐output case. The latter is of
interest because it can take advantage of redundancy in the different coefficient multipliers.
Graphical methods can be used to design multipliers in both cases.

For the one‐input/one‐output case, both optimal and sub‐optimal algorithms
introduced by the author are shown to be the best methods for the design of these
multipliers. The key to the new methods′ success is the use of different graph topologies
to those available under standard methods. The optimal method uses an exhaustive
search and is limited to short wordlengths, so the suboptimal methods must be used for
long wordlengths. The design is shown to be analogous to the design of algorithms for
exponentiation, which is becoming increasingly important in cryptography.

For the one‐input/several‐output (“multiplier block”) case, again new algorithms
designed by the author are shown to be the best. When used for designing digital filters,
the multiplier block method is more efficient (uses fewer adders) than any other method
that has been examined. It is so successful at reducing the number of adders used for
multiplication that the non‐multiplier elements begin to dominate the overall filter cost.
It also allows previously unpopular filter structures to compete with structures like the
lattice wave structure, despite having more coefficients of longer wordlength. The use of
multiplier blocks in filter banks is also described.

A third case is examined briefly, that of matrix multiplication (several‐input/several‐output),
which is an area of further research.