bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impact of Nef-Mediated Downregulation of Major Histocompatibility Complex Class I on Immune Response to Simian Immunodeficiency Virus
Authors: Swigut Tomek , Alexander Louis , Morgan Jennifer , Lifson Jeff , Mansfield Keith G. , Lang Sabine , Johnson R. Paul , Skowronski Jacek , Desrosiers Ronald 
Published: November 2004

ABSTRACT

Functional activities that have been ascribed to the
nef
gene product of simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) include CD4 downregulation, major histocompatibility complex (MHC) class I downregulation, downregulation of other plasma membrane proteins, and lymphocyte activation. Monkeys were infected experimentally with SIV containing difficult-to-revert mutations in
nef
that selectively eliminated MHC downregulation but not these other activities. Monkeys infected with these mutant forms of SIV exhibited higher levels of CD8
+
T-cell responses 4 to 16 weeks postinfection than seen in monkeys infected with the parental wild-type virus. Furthermore, unusual compensatory mutations appeared by 16 to 32 weeks postinfection which restored some or all of the MHC-downregulating activity. These results indicate that
nef
does serve to limit the virus-specific CD8 cellular response of the host and that the ability to downregulate MHC class I contributes importantly to the totality of
nef
function.
ON THE POWER OF ONE-WAY GLOBALLY DETERMINISTIC SYNCHRONIZED ALTERNATING TURING MACHINES AND MULTIHEAD AUTOMATA
Authors: SLOBODOVÁ ANNA 
Published: November 2004

The alternating model augmented by a special simple form of communication among parallel processes—the so-called synchronized alternating (SA) model, provides (besides others) nice characterizations of the space complexity classes defined by nondeterministic Turing machines. The model investigated in this paper — globally deterministic synchronized alternating (GDSA) model—is obtained by a feasible restriction of nondeterminism in SA. It is known that it characterizes the deterministic counterparts of the nondeterministic space classes characterized by the SA model. In the paper we resume in the investigation of GDSA solving the open questions about the computational power of the one-way GDSA models. It is known that in the case of space-bounded Turing machine and multihead automata, the one-way SA models are equivalent to their two-way counterparts. We show that the same holds for GDSA models. The results contribute to the knowledge about the model and imply new characterizations of the deterministic space complexity classes.
THE EFFECT OF INKDOTS FOR TWO-DIMENSIONAL AUTOMATA
Authors: ITO AKIRA , INOUE KATSUSHI , TAKANAMI ITSUO , WANG YUE 
Published: November 2004

Recently, related to the open problem of whether deterministic and nondeterministic space (especially lower-level) complexity classes are separated, the inkdot Turing machine was introduced. An inkdot machine is a conventional Turing machine capable of dropping an inkdot on a given input tape for a landmark, but not to pick it up nor further erase it. In this paper, we introduce a finite state version of the inkdot machine as a weak recognizer of the properties of digital pictures, rather than a Turing machine supplied with a one-dimensional working tape. We first investigate the sufficient spaces of three-way Turing machines to simulate two-dimensional inkdot finite automaton, as preliminary results. Next, we investigate the basic properties of two-dimensional inkdot automaton, i.e. the hierarchy based on the number of inkdots and the relationship of two-dimensional inkdot automata to other conventional two-dimensional automata. Finally, we investigate the recognizability of connected pictures of two-dimensional inkdot finite machines.
ON TOPOLOGY PRESERVATION IN 2-D AND 3-D THINNING
Authors: KONG T.Y. 
Published: November 2004

An (m, n)-simple 1 in a binary image I has the property that its deletion “preserves topology” when m-adjacency is used on the 1’s and n-adjacency on the 0’s of I. This paper presents new, easily visualized, necessary and sufficient conditions for a 1 in I to be (m, n)-simple, for (m, n)=(26, 6), (18, 6), (6, 26) or (6, 18) when I is a 3-d image and (m, n)=(8, 4) or (4, 8) when I is a 2-d image. Systematic and fairly general methods of verifying that a given parallel thinning algorithm always preserves topology are described, for the cases where 8-/26-adjacency is used on the 1’s and 4-/6-adjacency on the 0’s, or vice versa. The verification methods for 2-d algorithms are mainly due to Ronse and Hall; the methods for 3-d algorithms were found by Ma and Kong. New proofs are given of the correctness of these verification methods, using the characterizations of simple 1’s presented in this paper.
GENERALIZED INSTANTANEOUS AMPLITUDE AND FREQUENCY FUNCTIONS AND THEIR APPLICATION FOR PITCH FREQUENCY DETERMINATION
Authors: FÖLDVÁRI RUDOLF 
Published: November 2004

By defining an instantaneous frequency function it could be shown that if a signal is analytic, instantaneous frequency is analytic, too. A generalized instantaneous amplitude function could then be introduced which is also analytic in character. These functions — apart from an arbitrary constant phase — uniquely define the analytic time function. It could be proved that the transformation gives a true time-frequency representation which fulfills all the necessary requirements. Moreover, the application of instantaneous parameters in connection with a Zwicker's filter bank makes it possible even to model human hearing. By applying a simplified hearing model, an efficient pitch-frequency detector able to decide between voiced-unvoiced signals with the same reliability as visual detection even at a 0 dB signal-to-noise ratio could be developed.
APPLICATION OF SLIDING MODE CONTROL TO SWITCH-MODE POWER SUPPLIES
Authors: SPIAZZI G. , MATTAVELLI P. , ROSSETTO L. , MALESANI L. 
Published: November 2004

Switch-mode power supplies represent a particular class of variable structure systems (VSS). Thus, they can take advantage of non-linear control techniques developed for this class of systems. In this paper the so called sliding mode control is reviewed and its application to switch-mode power supplies is discussed. Sliding mode control extends the properties of hysteresis control to multi-variable environments, resulting in stability even for large supply and load variations, good dynamic response and simple implementation. Application to dc–dc converters, as well as rectifiers and inverters, is analyzed and provisions to overcome the inherent drawbacks of sliding mode control, i.e. variable switching frequency and possible steady-state errors, are described. Experimental results are also reported, which allow a comparison between the sliding mode approach and other standard control techniques, e.g. current-mode control, showing its effectiveness.
PHYSICAL MODELING OF POWER SEMICONDUCTORS FOR THE CAE-DESIGN OF POWER ELECTRONIC CIRCUITS
Authors: VOGLER THOMAS , SCHRÖDER DIERK 
Published: November 2004

CAE-tools can help to develop any traditional or novel power conversion topology more efficiently, by providing both the possibilities of investigation without the risk of destruction and of access to each signal in the circuit. However, a prerequisite are trustworthy simulation results both qualitatively for operation observation and quantitatively for power dissipation examination as well as for SOA control. This implies that precise power semiconductor models have to be used. In the variety of different possible modeling strategies there is only the strictly physical way which offers topology independent accurate results. In this paper a new class of physical high performance and high accuracy circuit models for today's relevant power semiconductors (Power-Diode, GTO, IGBT, Power-MOSFET) is presented. A modular concept, handling typical features of power devices like ν-zones, MOSFET controlling units or diffusion zones as basic structures, is used which allows a considerable flexibility to model future devices time efficiently. The core of this modular concept, constituted by a module of the ν-zone, employs a universal and powerful solution technique of the ambipolar diffusion equation. This technique is the only possibility for circuit models to consider physically semiconductor technology measures for improving device characteristics, such as particle irradiation for lifetime reduction, step doping of substrate or epitaxial layers as well as double diffused layers.
PUSHING STANDARD CMOS TECHNOLOGIES INTO SMART POWER CONVERSION AND AMPLIFICATION
Authors: FINCO S. , BEHRENS F. H. , GUILHERME J. , CASTRO SIMAS M. I. , LANÇA M. 
Published: November 2004

A smart power integrated circuit to be fabricated with standard CMOS technologies was developed in view to obtain a versatile, high performance and low cost basic building block, suitable for a wide range of low power applications. This circuit merges together two transistors, connected in a low-side/high-side switch configuration, with specific control and protection circuitries. These transistors are NMOS medium-voltage lateral structures, which use the lightly doped drain concept and are targeted to handle currents up to 2 A and to support 25 V at OFF state. Experimental results on different applications and topologies show the applicability of the smart switching cell on portable systems power supplies and amplifiers (up to 20 W). Its performance also proves the ability of standard CMOS technologies to implement smart power circuits.
APPLICATION OF A BOOST RECTIFIER IN A HIGH PERFORMANCE DC DRIVE
Authors: RODRÍGUEZ J. , SUÁREZ A. , HERNÁNDEZ J. , ANDRADE H. , WIECHMANN E. 
Published: November 2004

This paper presents the use of a single-phase voltage-doubler Boost rectifier, to generate a controlled DC voltage, which is applied to a four-quadrant chopper. The transistor chopper controls the speed of a separately excited DC machine. The Boost rectifier permits the regeneration of energy from the motor to the single-phase mains, maintaining in all operating points a practically sinusoidal input current, with a THD of 2.5%. The balancing of the two filter capacitors is achieved by using and additional control loop. A low cost microcontroller is used to control the DC voltage and the motor speed.
MULTI-VALUED CONSTANT PROPAGATION ANALYSIS FOR USER INTERFACE REENGINEERING
Authors: MERLO ETTORE , GIRARD JEAN-FRANCOIS , HENDREN LAURIE , DE MORI R. 
Published: November 2004

The definition and use of multi-valued constant propagation analysis (MVCP), which is an extension of simple constant propagation analysis, is presented in this paper in the context of a user interface reengineering process. A brief description of the adopted COBOL/CICS user interface reengineering model, which makes use of an Abstract User Interface Description Language (AUIDL) to represent user interface structures and behavior, is also given. The experimental context is described and results are shown and discussed. Suggestions for further directions of research and investigation are also presented.
HOW TO COMBINE NONMONOTONIC LOGIC AND RAPID PROTOTYPING TO HELP MAINTAIN SOFTWARE
Authors: LUQI  , COOKE DANIEL E. 
Published: November 2004

This paper explores the possibility of automated support for detecting inconsistencies in software systems and requirements. The inconsistencies are introduced when the environment of the software system changes. We refer to the software environment as its context. We review the recent research progress on nonmonotonic logics, pointing out the significance of these results to software maintenance. We explain how a practical implementation of such logics can be obtained via a simple extension to logic programming in the form of an answer procedure that realizes the Extended Logic Semantics [7] for nonmonotonic logic programs that have a unique answer set (which is a large and useful class of logic programs). We augment the existing automated capabilities of the Computer-Aided Prototyping System (CAPS) for rapid prototyping via the extension to logic programming to provide an improved automated capability for detecting certain kinds of inconsistencies created by implicit requirements changes. We illustrate the significance of this capability via an example prototype for a problem originally suggested by Lehman.
AUTOMATIC PROGRAMMING AND PROGRAM MAINTENANCE WITH GENETIC PROGRAMMING
Authors: PETRY FREDERICK E. , DUNAY BERTRAND DANIEL 
Published: November 2004

Automatic programming is discussed in the context of software engineering. An approach to automatic programming is presented, which utilizes software engineering principles in the synthesis and maintenance of programs. As a simple demonstration, program-equivalent Turing machines are synthesized, encapsulated, reused, and maintained by genetic programming. Turing machines are synthesized from input-output pairs for a variety of simple problems. When a problem is solved, the solution is encapsulated and becomes part of a software library. The genetic program uses the library to solve new problems by combining library components with program primitives to synthesize new programs. When a new problem is solved or a known problem is solved more efficiently, the genetic program maintains the library so as to keep it valid and efficient.
PARTS: A TEMPORAL LOGIC-BASED REAL-TIME SOFTWARE SPECIFICATION METHOD SUPPORTING MULTIPLE VIEWPOINTS
Authors: KANG KYO C. , KO KWANG-IL 
Published: November 2004

Areas of computer application are being broadened rapidly due to the rapid improvement of the performance of computer hardware. This results in increased demands for computer applications that are large and have complex temporal characteristics. This paper introduces a real-time systems anlaysis method named PARTS. PARTS supports analyses from two viewpoints: external viewpoint, a view of the system from the user's perspective, and internal viewpoint, a view from the developer's perspective. These viewpoints are specified using formal languages, which are Real-Time Events Trace (RTET) for the external viewpoint, and Time Enriched Statechart (TES) and PARTS Data Flow Diagram (PDFD) for the internal viewpoint. All PARTS languages are based on the Metric Temporal Logic (MTL), and consistency of the specifications made from the two different viewpoints are analyzed based on the same MTL formalism.
FACT UPDATES IN LOGIC DATABASES
Authors: HUANG YAN-NONG , DAHL VERONICA , HAN JIAWEI 
Published: November 2004

A logic database has two components. One comprises the base knowledge, represented explicitly, called the extensional base. The other stores more general knowledge in the form of derivation rules, and is called the intensional base. One may calculate derived facts in advance and store (or materialize) them. Thus, the response time can be expected to speed up. In this paper, we study a new evaluation technique for incrementally maintaining derived facts whenever updates occur on base facts. Our method is based on the seminaive evaluation so it is easy to implement; it is set-oriented, multiple updates may be dealt within a single manipulation; and insertion and deletion are treated uniformly. The method is evaluated analytically as well as experimentally. We indicate the potential application of our incremental method to a computational linguistic problem, i.e., parsing incomplete sentences. Related work in both areas of logic databases and computational linguistics are discussed.
"ENTREPRENEURIAL SURVIVAL SKILLS IN THE MIDST OF ECONOMIC CHAOS" AN ANALYSIS OF SMALL BUSINESSES PRIOR TO THE GENERAL ELECTION OF 1992 IN GUYANA
Authors: RAGHUNANDA M. 
Published: November 2004

It is generally agreed that small businesses tangibly contribute to both the stability and health of the national economy. They employ more than 25% of the workforce, produce on an on-going basis a tidy revenue for the state and create more than 50% of the new jobs. The pioneers behind these businesses are the entrepreneurs who understand the organizations' purpose and can best devise methods to exploit the windows of opportunities. This paper reviews several pieces of literature on small businesses in Guyana in order to provide an understanding of the entrepreneurial survival strategies employed to keep the businesses open. Studies show that entrepreneurial behaviour, management skills and competence were key ingredients in the successful operation of small businesses in Guyana. The results indicate that twenty four entrepreneurial routes were successfully followed to float small businesses prior to the Guyanese 1992 general election. The paper concludes by making some pronouncements on the future of small businesses in Guyana and supports the drive for the state to empower the entrepreneurs and the people for development.
Retroperitoneoscopic Ureterolithotomy for the Treatment of Ureteral Calculi
Authors: Demirci Deniz , Gülmez İbrahim , Ekmekçioğlu Oğuz , Karacagil Mustafa 
Published: November 2004

<i>Introduction:</i> Most upper or middle ureteral stones are treated with shock wave lithotripsy or endoscopic techniques. In rare cases the ureteral stones are treated with open surgery after failure of first-line treatments. Retroperitoneoscopy is a minimally invasive alternative to open surgery. <i>Patients and Methods:</i> Between May 1995 and January 2001, twenty-one patients underwent retroperitoneoscopic ureterolithotomy. The stones in upper and middle ureter were large and impacted (5 patients) or not fragmented after shock wave lithotripsy (16 patients). A balloon dissector was placed and infiltrated with 800 ml air in the retroperitoneal space. Three 10-mm trocars were used. The pressure was kept at 15 mm Hg by carbon dioxide insufflation. The stones were extracted from the ureter using a laparoscopic stylet. <i>Results:</i> The stones in 17 patients were successfully removed in a median operating time of 105 (min–max 45–190) min. Urine extravasation in all cases and pnomoscrotum in 2 cases were observed as postoperative complications. The median hospital stay was 6 (min–max 3–22) days with minimal analgesic requirement. <i>Conclusion:</i> Retroperitoneoscopic ureterolithotomy is a useful and effective alternative treatment technique to open surgery when first-line treatments have failed or are unlikely to be effective.
An Improved Time Interpolation for Three-Dimensional Doppler Wind Analysis
Authors: Liu Shun , Qiu Chongjian , Xu Qin , Zhang Pengfei 
Published: November 2004

Abstract
A temporal interpolation is required for three-dimensional Doppler wind analysis when the precise measurement time is counted for each radar beam position. The time interpolation is traditionally done by a linear scheme either in the measurement space or in the analysis space. Because a volume scan often takes 5–10 min, the linear time interpolation is not accurate enough to capture the rapidly changing winds associated with a fast-moving and fast-growing storm. Performing the linear interpolation in a frame moving with the storm can reduce the error, but the analyzed wind field is traditionally assumed to be stationary in the moving frame. The stationary assumption simplifies the computation but ignores the time variation of the true wind field in the moving frame. By incorporating a linear time interpolation into the moving frame wind analysis, an improved scheme is developed. The merits of the new scheme are demonstrated by idealized examples and numerical experiments with simulated radar observations. The new scheme is also applied to real radar data for a supercell storm.
Sensitivity of Perturbation Variance and Fluxes in Turbulent Jets to Changes in the Mean Jet
Authors: Farrell Brian F. , Ioannou Petros J. 
Published: November 2004

Abstract
Synoptic-scale eddy variance and fluxes of heat and momentum in midlatitude jets are sensitive to small changes in mean jet velocity, dissipation, and static stability. In this work the change in the jet producing the greatest increase in variance or flux is determined. Remarkably, a single jet structure change completely characterizes the sensitivity of a chosen quadratic statistical quantity to modification of the mean jet in the sense that an arbitrary change in the jet influences a chosen statistical quantity in proportion to the projection of the change on this single optimal structure. The method used extends previous work in which storm track statistics were obtained using a stochastic model of jet turbulence.
The Connection between Coherent Structures and Low-Frequency Wave Packets in Large-Scale Atmospheric Flow
Authors: Hodyss Daniel , Nathan Terrence R. 
Published: November 2004

Abstract
A theory is presented that addresses the connection between low-frequency wave packets (LFWPs) and the formation and decay of coherent structures (CSs) in large-scale atmospheric flow. Using a weakly nonlinear evolution equation as well as the nonlinear barotropic vorticity equation, the coalescence of LFWPs into CSs is shown to require packet configurations for which there is a convergent group velocity field. These LFWP configurations, which are consistent with observations, have shorter wave groups with faster group velocities upstream of longer wave groups with slower group velocities. These wave group configurations are explained by carrying out a kinematic analysis of wave focusing, whereby a collection of wave groups focus at some point in space and time to form a large amplitude wave packet having a single wave front. The wave focusing and the subsequent formation of CSs are enhanced by zonal variations in the background flow, while nonlinearity extends the lifetimes of the CSs. These results are discussed in light of observed blocking formation in the Atlantic–European and South Pacific regions.
Clouds and Shortwave Fluxes at Nauru. Part II: Shortwave Flux Closure
Authors: McFarlane Sally A. , Evans K. Franklin 
Published: November 2004

Abstract
The datasets currently being collected by the Atmospheric Radiation Measurement (ARM) program on the islands of Nauru and Manus represent the longest time series of ground-based cloud measurements in the tropical western Pacific region. In this series of papers, a shortwave flux closure study is presented using observations collected at the Nauru site between June 1999 and May 2000. The first paper presented frequency of occurrence of nonprecipitating clouds detected by the millimeter-wavelength cloud radar (MMCR) at Nauru and statistics of their retrieved microphysical properties. This paper presents estimates of the cloud radiative effect over the study period and results from a closure study in which retrieved cloud properties are input to a radiative transfer model and the modeled surface fluxes are compared to observations.
The average surface shortwave cloud radiative forcing is 48.2 W m−2, which is significantly smaller than the cloud radiative forcing estimates found during the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) field project. The difference in the estimates during the two periods is due to the variability in cloud amount over Nauru during different phases of the El Niño–Southern Oscillation (ENSO). In the closure study, modeled and observed surface fluxes show large differences at short time scales, due to the temporal and spatial variability of the clouds observed at Nauru. Averaging over 60 min reduces the average root-mean-square difference in total flux to 10% of the observed flux. Modeled total downwelling fluxes are unbiased with respect to the observed fluxes while direct fluxes are underestimated and diffuse fluxes are overestimated. Examination of the differences indicates that cloud amount derived from the ground-based measurements is an overestimate of the radiatively important cloud amount due to the anisotropy of the cloud field at Nauru, interpolation of the radar data, uncertainty in the microwave brightness temperature measurements for thin clouds, and the uncertainty in relating the sixth moment of the droplet size distribution observed by the radar to the more radiatively important moments.