bluuebunny/crossref_metadata_2025 huggingface dataset:
Ray space factorization for from-region visibility
Authors: Leyvand Tommer , Sorkine Olga , Cohen-Or Daniel
Published: October 2003

From-region visibility culling is considered harder than from-point visibility culling, since it is inherently four-dimensional. We present a conservative occlusion culling method based on factorizing the 4D visibility problem into horizontal and vertical components. The visibility of the two components is solved asymmetrically: the horizontal component is based on a parameterization of the ray space, and the visibility of the vertical component is solved by incrementally merging umbrae. The technique is designed so that the horizontal and vertical operations can be efficiently realized together by modern graphics hardware. Similar to image-based from-point methods, we use an occlusion map to encode visibility; however, the image-space occlusion map is in the ray space rather than in the primal space. Our results show that the culling time and the size of the computed potentially visible set depend on the size of the viewcell. For moderate viewcells, conservative occlusion culling of large urban scenes takes less than a second, and the size of the potentially visible set is only about two times larger than the size of the exact visible set.
Accurate light source acquisition and rendering
Authors: Goesele Michael , Granier Xavier , Heidrich Wolfgang , Seidel Hans-Peter
Published: October 2003

Realistic image synthesis requires both complex and realistic models of real-world light sources and efficient rendering algorithms to deal with them. In this paper, we describe a processing pipeline for dealing with complex light sources from acquisition to global illumination rendering. We carefully design optical filters to guarantee high precision measurements of real-world light sources. We discuss two practically feasible setups that allow us to measure light sources with different characteristics. Finally, we introduce an efficient importance sampling algorithm for our representation that can be used, for example, in conjunction with Photon Maps.
Record/replay for nondeterministic program executions
Authors: Ronsse Michiel , De Bosschere Koen , Christiaens Mark , de Kergommeaux Jacques Chassin , Kranzlmüller Dieter
Published: October 2003

Controlling the nondeterministic features within multithreaded and highly responsive applications enables the continued use of all traditional software development techniques.
Power to the people
Authors: McGinity Meg
Published: October 2003

Broadband access gets electrified.
Responding to the unexpected
Authors: Arens Yigal , Rosenbloom Paul S.
Published: October 2003

How IT can help prepare for future attacks and disasters.
A dynamic approach to characterizing termination of general logic programs
Authors: Shen Yi-Dong , You Jia-Huai , Yuan Li-Yan , Shen Samuel S. P. , Yang Qiang
Published: October 2003

We present a new characterization of termination of general logic programs. Most existing termination analysis approaches rely on some static information about the structure of the source code of a logic program, such as modes/types, norms/level mappings, models/interargument relations, and the like. We propose a dynamic approach that employs some key dynamic features of an infinite (generalized) SLDNF-derivation, such as repetition of selected subgoals and recursive increase in term size. We also introduce a new formulation of SLDNF-trees, called generalized SLDNF-trees. Generalized SLDNF-trees deal with negative subgoals in the same way as Prolog and exist for any general logic programs.
Class analyses as abstract interpretations of trace semantics
Authors: Spoto Fausto , Jensen Thomas
Published: October 2003

We use abstract interpretation to abstract a compositional trace semantics for a simple imperative object-oriented language into its projection over a set of program points called
watchpoints
. We say that the resulting
watchpoint semantics
is
focused
on the watchpoints. Every abstraction of the computational domain of this semantics induces an abstract, still compositional, and focused watchpoint semantics. This establishes a basis for developing static analyses obtaining information pertaining only to the watchpoints. As an example, we consider three domains for class analysis of object-oriented programs derived from three techniques present in the literature, namely, rapid type analysis, a simple dataflow analysis, and a constraint-based analysis. We obtain three static analyses which are provably correct and whose abstract operations are provably optimal. Moreover, we prove that our formalization of the constraint-based analysis is more precise than that of the other two analyses. We have implemented our watchpoint semantics and our three domains for class analysis. This implementation shows that the time and space costs of the analysis are actually proportional to the number of watchpoints, as a consequence of the focused nature of the watchpoint semantics.
Generating LR syntax error messages from examples
Authors: Jeffery Clinton L.
Published: October 2003

LR parser generators are powerful and well-understood, but the parsers they generate are not suited to provide good error messages. Many compilers incur extensive modifications to the source grammar to produce useful syntax error messages. Interpreting the parse state (and input token) at the time of error is a nonintrusive alternative that does not entangle the error recovery mechanism in error message production. Unfortunately, every change to the grammar may significantly alter the mapping from parse states to diagnostic messages, creating a maintenance problem.
Merr
is a tool that allows a compiler writer to associate diagnostic messages with syntax errors by example, avoiding the need to add error productions to the grammar or interpret integer parse states. From a specification of errors and messages, Merr runs the compiler on each example error to obtain the relevant parse state and input token, and generates a yyerror() function that maps parse states and input tokens to diagnostic messages. Merr enables useful syntax error messages in LR-based compilers in a manner that is robust in the presence of grammar changes.
Me and my shadow
Authors: Weiss Aaron
Published: October 2003

RFID tags polarize the debate over privacy vs. efficiency
A data acquisition methodology for on-chip repair of embedded memories
Authors: Niggemeyer Dirk , Rudnick Elizabeth M.
Published: October 2003

Systems-on-Chips often contain a large amount of embedded memory. In order to obtain sufficiently high yield, efficient diagnosis and repair facilities are needed for the memories. A novel and efficient approach for collecting complete failure data during on-chip memory testing is proposed that can be combined with a row/column reconfiguration algorithm for complete on-chip memory repair. A sequence of diagnostic tests of linear order is utilized that detects and localizes all cells involved in single-cell faults and two-cell coupling faults, such as idempotent coupling faults, and provides this information to on-chip circuitry for memory repair. Failure data are collected at the operating speed of the memory-under-test so that tests can be applied at speed. The data acquisition circuitry evaluates the test results and classifies faults as column failures, coupling faults, or single-cell faults for near-optimal allocation of spare resources. The proposed test and data acquisition algorithm can be realized as compact Built-In Self-Test (BIST) circuitry using standard design libraries.
Method engineering for OO systems development
Authors: Henderson-Sellers Brian
Published: October 2003

This metamodel-based framework helps distill the key ingredients in software engineering processes in ways that facilitate method engineering, along with process understanding.
Different Behavior of Iron(III) and Aluminum(III) Salts To Coagulate Silica Particle Suspension
Authors: Zhang Panyue , Hahn Hermann H. , Hoffmann Erhard
Published: October 2003

The different coagulation‐flocculation behavior of iron(III) and aluminum(III) to coagulate silica particle suspension with four coagulants — FeCl3, Fe2(SO4)3, AlCl3, and in our laboratory produced polyaluminum chloride PACl‐2.0 — was investigated through studying particle property changes and coagulation efficiency, for example, variations in zeta potential of particles, particle number, average particle diameter, particle size distribution, and residual turbidity of the supernatant water. Influences of flocculation intensity and pH value on the coagulation‐flocculation process were also studied. The results suggest that, under the test conditions, among these four coagulants FeCl3 possesses an obviously stronger ability to form larger flocs and to remove turbidity, on the other hand, PACl‐2.0 obviously showed a better charge neutralization ability.
Osteoarthritis of the knee is associated with vertebral and nonvertebral fractures in the elderly: The Rotterdam Study
Authors: Bergink Arjan P. , Van Der Klift Marjolein , Hofman Albert , Verhaar Jan A. N. , Van Leeuwen Johannes P. T. M. , Uitterlinden André G. , Pols Huibert A. P.
Published: October 2003

Objective

To study the association between prevalent radiographic osteoarthritis (ROA) of the knee and incident vertebral and nonvertebral fractures.

Methods

A sample of 2,773 subjects was drawn from the Rotterdam Study, a prospective population‐based cohort study of the elderly. Status on knee ROA was assessed at baseline using the Kellgren score. Incident nonvertebral fractures were scored for all subjects, and for 1,466 subjects additional data on incident vertebral fractures were available.

Results

Although people with ROA had a higher bone mineral density (BMD), their incident fracture risk was increased as compared with those without ROA. After adjustment for potential confounding factors, including parameters of postural stability, the relative risks for incident vertebral and nonvertebral fractures in the presence of knee ROA were 2.0 (95% confidence interval [95% CI] 1.1–3.4) and 1.5 (95% CI 1.1–2.0), respectively.

Conclusions

Knee ROA is associated with an increased risk of incident vertebral and nonvertebral fractures, independent of BMD and parameters of postural stability.
Performance of a generic health‐related quality of life measure in a clinic population with rheumatic disease
Authors: Currey Shannon S. , Rao Jaya K. , Winfield John B. , Callahan Leigh F.
Published: October 2003

Objective

To assess the performance of a generic health‐related quality of life (HRQOL) measure in a rheumatology clinic population.

Methods

Participants (n = 619) with fibromyalgia, rheumatoid arthritis, or osteoarthritis receiving care from rheumatologists completed mailed questionnaires that included the Behavioral Risk Factor Surveillance System (BRFSS) HRQOL measure and condition‐specific measures assessing disability, pain, fatigue, and helplessness. The BRFSS assesses global health and number of days in the past 30 of poor physical or mental health or activity limitation. The overall sample was described, followed by comparison of adjusted scores on all HRQOL measures by diagnosis.

Results

Participants reported mild difficulty with activities of daily living, marked pain and fatigue, and moderate helplessness. Participants reported a mean of 8 or more days out of 30 of poor physical and mental health and activity limitations; more than 40% reported poor or fair health. Participants with fibromyalgia reported more ill health on condition‐specific measures and the BRFSS HRQOL measures than did participants with osteoarthritis or rheumatoid arthritis.

Conclusion

The BRFSS HRQOL measure is a brief, easily administered, generic health indicator that shows differences among rheumatic disease diagnoses.
Systemic sclerosis: Patients' perceptions of their condition
Authors: Richards Helen L. , Herrick Ariane L. , Griffin Kerry , Gwilliam Petra D. H. , Loukes Jonathan , Fortune Dónal G.
Published: October 2003

Objective

To examine patients' beliefs about systemic sclerosis (SSc) and to investigate the relationship between these beliefs, symptom report, and clinical and demographic variables.

Methods

A total of 49 patients (7 male, 42 female) with SSc underwent clinical examination and completed the Revised Illness Perception Questionnaire. This measure assesses beliefs about symptoms, chronicity or recurrence of the condition, consequences, personal and treatment control, illness coherence, perceived causes of the condition, and patients' emotional response to their condition.

Results

The symptoms patients most frequently associated with their SSc were stiff joints (79%), pain (75%), and fatigue (75%). The most commonly reported causes of SSc were stress (53%), altered immunity (49%), and chance or bad luck (46%). More than 96% of patients believed that their condition would be chronic and 78% believed that the condition had serious consequences on their lives. Patients with diffuse cutaneous SSc reported more significant consequences of the condition and less personal control of their SSc compared with patients with limited cutaneous disease. There were no significant differences in illness beliefs between patients with nonsevere and severe ischemia. Multiple regression analyses indicated that illness beliefs, in particular perceived consequences associated with the condition, accounted for a significant proportion of the variance in emotional response to the condition.

Conclusions

The beliefs held and symptoms experienced by patients with SSc are not ruled by disease subtype, skin score, functional ability, or severity of digital ischemia. This suggests patients' beliefs and emotional response are associated with the meaning they ascribe to their condition rather than its severity.
Leadership development: The Role of the President‐Board Team
Authors: Vaughan George B. , Weisman Iris M.
Published: October 2003

Preparing the next generation of community college presidents is a responsibility shared by many. A largely untapped source is the president‐board team, which has primary responsibility for campus‐based presidential leadership development programs.
Synthesis of a Hexagonal Nanosized Macrocyclic Fluorophore with Integrated Endotopic Terpyridine Metal‐Chelation Sites
Authors: Baxter Paul N. W.
Published: October 2003

A rigid nanosized hexagonal phenylethynyl cyclophane 5 has been prepared, which incorporates two 2,2′:6′,2″‐terpyridines as integral structural units, for the purpose of binding metal ions. Macrocycle 5 was obtained by a 14‐step synthesis in an overall yield of 11 %, and was characterised by spectroscopic techniques. The efficiency and ease of all transformations, and the relatively enhanced yield of the final macrocyclisation suggests that the entire synthetic pathway should be amenable to scale‐up. Cyclophane 5 possesses four bulky triisopropylsilyl(TIPS)‐protected ethyne substituents which serve a dual role. Firstly, they solubilise the structure thereby facilitating purification and subsequent handling. Secondly, they enable post‐synthetic modification in which additional functionality may be attached to the periphery of the ring. Significantly, 5 was found to be a fluorescent chromophore, and may therefore potentially function as a new sensory platform for the detection of metal ions and H‐bond donating biological substrates. The structurally well‐defined nanosized morphology of 5, coupled with its interesting spectroscopic properties, supports the expectation that 5 and related architectures will attain a wealth of future applications within the developing fields of nanochemistry and nanoscience.
Stereoselective Aldol Additions Catalyzed by Dihydroxyacetone Phosphate‐Dependent Aldolases in Emulsion Systems: Preparation and Structural Characterization of Linear and Cyclic Iminopolyols from Aminoaldehydes
Authors: Espelt Laia , Parella Teodor , Bujons Jordi , Solans Conxita , Joglar Jesús , Delgado Antonio , Clapés Pere
Published: October 2003

The potential of dihydroxyacetone phosphate (DHAP)‐dependent aldolases to catalyze stereoselective aldol additions is, in many instances, limited by the solubility of the acceptor aldehyde in aqueous/co‐solvent mixtures. Herein, we demonstrate the efficiency of emulsion systems as reaction media for the class I fructose‐1,6‐bisphosphate aldolase (RAMA) and class II recombinant rhamnulose‐1‐phosphate aldolase from E. coli (RhuA)‐catalyzed aldol addition between DHAP and N‐benzyloxycarbonyl (N‐Cbz) aminoaldehydes. The use of emulsions improved the RAMA‐catalyzed aldol conversions by three to tenfold relative to those in conventional DMF/water mixtures. RhuA was more reactive than RAMA towards the N‐Cbz aminoaldehydes regardless of the reaction medium. With (S)‐ or (R)‐Cbz‐alaninal, RAMA exhibited preference for the R enantiomer, while RhuA had no enantiomeric discrimination. The linear N‐Cbz aminopolyols thus obtained were submitted to catalytic intramolecular reductive amination to afford the corresponding iminocyclitols. This reaction was diastereoselective in all cases examined; the face selectivity was controlled by the stereochemistry of the newly formed hydroxyl group originating from the aldehyde. Characterization of the resulting iminocyclitols allowed the assessment of the diastereoselectivity of the enzymatic aldol reactions with respect to the N‐protected aminoaldehyde. RAMA formed single diastereoisomers from N‐Cbz‐glycinal and from both enantiomers of N‐Cbz‐alaninal, while 14 % of the epimeric product was observed from N‐Cbz‐3‐aminopropanal. Diastereoselectivity from RhuA was lower than that observed from RAMA. Interestingly, a single diastereoisomer was formed from (S)‐Cbz‐alaninal, whereas only a 34 % diastereomeric excess was observed from its enantiomer (i.e., (R)‐Cbz‐alaninal).
Low frequency bursts and ionization instabilities in weakly ionized plasmas
Authors: Alcaide I. , Balam P.C. , Conde L. , Ionita C. , Schrittwieser R.
Published: October 2003

In this paper we report time dependent ion density bursts observed during the electron collection process from an unmagnetized plasma by a positively polarized electrode. For bias voltages over a threshold a double layer develops and the electron drained current exceeds the thermal levels. The energized electrons by the plasma potential voltage drop would excite a ionization instability in the plasma located at the high potential side, causing the subsequent fluctuations in the ion current downstream the double layer. These oscillations in the ion density were detected as abrupt decrements in the electron saturation current of a collecting Langmuir probe, located in Maxwellian background plasma, away form the double layer. The time elapsed between two successive jumps in ion density decreases with the amount of current drained by the metallic electrode. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Alcohol intake in social housing and in isolation before puberty and its effects on voluntary alcohol consumption in adulthood
Authors: Juárez Jorge , Vázquez‐Cortés Cristina
Published: October 2003

We assessed the effects of alcohol exposure in social and isolation housing before puberty on the alcohol consumption later in adulthood. From 25 to 35 days of age, Wistar male rats were exposed to either (a) continuous isolation; (b) continuous social housing; (c) continuous isolation, but placed in social housing during 12 hr every other day; or (d) continuous social housing, but placed in isolation during 12 hr every other day (SOIS group). All males were exposed to 8% ethanol as the only available liquid 12 hr/day every other day in this prepubescent period and to continuous free‐choice access to 8% ethanol or water in both social and isolation housing when adulthood was reached. Alcohol consumption before puberty was higher in the group permanently housed in isolation. Both voluntary alcohol intake and preference for alcohol in adulthood also were higher during the isolation than in the social condition in all groups, except in the SOIS group. Alcohol consumption was higher in the SOIS group than in the other groups only during social condition in adulthood. Food intake decreased during the social interaction of the groups that changed their condition from isolated to social or from social to isolated. Results support that (a) isolation facilitates alcohol consumption, and (b) rearing characteristics associated to alcohol intake at an early age can play an important role in later alcohol intake. © 2003 Wiley Periodicals, Inc. Dev Psychobiol 43: 200–207, 2003.
Short‐term stability of physiological measures in kindergarten children: Respiratory sinus arrhythmia, heart period, and cortisol
Authors: Doussard‐Roosevelt Jane A. , Montgomery Lee Anne , Porges Stephen W.
Published: October 2003

The short‐term stability of measures of respiratory sinus arrhythmia (RSA), heart period, and salivary cortisol and the relation of these variables to one another and to measures of social competence in kindergartners were examined. Physiological measures were collected during multiple individual sessions with 30 kindergarten children, ages 5 to 6 years. Three sessions were scheduled at 2‐week intervals and included a negative affect task as a challenge. Cardiovascular and cortisol responses to the challenge were assessed. Results indicated that baseline measures of RSA and heart period were stable across time. Baseline cortisol levels were not stable. The change in RSA in response to a task that elicited emotional responses was not stable over time. Consistent with findings observed in adults and older children, changes in RSA were related to the cortisol response. Children who increased cortisol over the course of Session 1 exhibited larger decreases in RSA than children who did not show increased cortisol levels. In addition, the children who had larger decreases in RSA had higher ratings of sociability on the Colorado Childhood Temperament Inventory. Greater decreases in heart period during the task were associated with lower ratings of shyness. The relation of RSA measures to ratings of social competence supports the Polyvagal Theory (Porges, 1995, 2001), which suggests that the ability to engage and disengage with objects and people in one's environment, necessary for social competence, is related to the regulation of vagal control of the heart. © 2003 Wiley Periodicals, Inc. Dev Psychobiol 43: 230–242, 2003.
Operation and economy of a refuse‐fired generating system with electricity wheeling service
Authors: Kemmoku Yoshishige , Fujiwara Yoshikazu , Takikawa Hirofumi , Sakakibara Tateki
Published: October 2003

Electric power markets have been partially liberalized and liberalization will be proceeding steadily. On the other hand, refuse‐fired generating systems (RGS) are constructed in many municipal corporations as on‐site power sources. This paper discusses the operation of an RGS which can transfer its excess energy to consumers through the electricity wheeling service of the electric utility. The RGS is operated by the dynamic programming method under the constraints of RGS operation and electricity wheeling service. In the DP method, the estimation function is the annual total electricity charge of both the RGS and the consumers, and the control variable is the residual amount in the refuse pit. A university, hospitals, welfare apartment houses, and their combinations are selected as consumers. The main results obtained are as follows: (1) electricity wheeling service is more economical than the absence of electricity wheeling service when the annual demand of the consumer is higher than 70% of the excess energy of RGS; (2) it is more economical as the load factor increases if the annual demand is the same; (3) the most economical consumer is the combination of four hospitals and five welfare apartment houses, for which the total electricity charge can be reduced to 84% of that in the absence of wheeling service. It is concluded that the total electricity charge of the RGS with electricity wheeling service could be decreased considerably by selecting the consumers appropriately. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(1): 59–69, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10211
Transient response of a grounding system in an underground GIS substation
Authors: Okabe Shigemitsu , Yamada Michio , Nojima Kenichi , Suzuki Katsumi
Published: October 2003

The transient grounding impedance of a gas‐insulated switchgear (GIS) substation was investigated through measurements on a commercial 300‐kV underground substation. Using the results, the transient impedance of the grounding grid was investigated. The attenuation factor of the propagation line composed of the outer surface of the GIS tank and the concrete floor was also evaluated. The validity of EMTP analysis of surge phenomena in the GIS grounding system was confirmed. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(1): 70–77, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10214
Feasible enhancement of a three‐phase soft‐switching inverter with an auxiliary resonant DC link snubber
Authors: Kurokawa Manabu , Konishi Yoshihiro , Nakaoka Mutsuo
Published: October 2003

The purpose of this paper is to improve power conversion efficiency of a three‐phase voltage source type soft‐switching inverter with a single auxiliary resonant DC link (ARDCL) snubber. First, the operating principle of an ARDCL snubber discussed here is described. Second, this paper proposes an effective pulse pattern generation method of the zero voltage space vector of the three‐phase soft‐switching inverter using IGBTs or power modules that can reduce power losses in the ARDCL snubber treated here. In particular, a zero voltage holding interval in the DC rail busline of this three‐phase soft‐switching inverter is to be regulated according to the generation method of the zero voltage space vector. Third, the maximum modulation depth Mmax under the condition of correction of the instantaneous voltage space vector can be improved by using a new zero voltage space vector generation method. Finally, the feasible experimental results of this inverter are obtained confirming the operating characteristics such as power conversion actual efficiency, as well as conventional efficiency THD and RMS value of the balanced three‐phase output voltage for an experimentally built three‐phase voltage source type soft‐switching pulse modulated inverter using the latest IGBT modules and evaluated from the standpoint of practical applications in industry UPS and new energy systems. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(1): 89–99, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10234
Influence of wave front steepness and accumulated charge on creeping discharge
Authors: Ueno Hideki , Nakayama Hiroshi
Published: October 2003

The creeping flashover voltage–time characteristics for the composite insulating configuration by insertion of a barrier between a needle electrode and a plane electrode in N2 gas have been investigated. A maximum creeping flashover voltage of around 10 µs has been found in N2 gas for negative polarity. This anomalous voltage–time characteristic is associated with the low field relaxation effect of the accumulated charges on the barrier for an applied pulse voltage with a highly steep wave front. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(1): 1–8, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10249
Logistic regression of family data from retrospective study designs
Authors: Whittemore Alice S. , Halpern Jerry
Published: October 2003

We wish to study the effects of genetic and environmental factors on disease risk, using data from families ascertained because they contain multiple cases of the disease. To do so, we must account for the way participants were ascertained, and for within‐family correlations in both disease occurrences and covariates. We model the joint probability distribution of the covariates of ascertained family members, given family disease occurrence and pedigree structure. We describe two such covariate models: the random effects model and the marginal model. Both models assume a logistic form for the distribution of one person's covariates that involves a vector β of regression parameters. The components of β in the two models have different interpretations, and they differ in magnitude when the covariates are correlated within families. We describe ascertainment assumptions needed to estimate consistently the parameters βRE in the random effects model and the parameters βM in the marginal model. Under the ascertainment assumptions for the random effects model, we show that conditional logistic regression (CLR) of matched family data gives a consistent estimate ${\hat{\beta }}_{RE} $ for βRE and a consistent estimate for the covariance matrix of ${\hat{\beta }}_{RE} $. Under the ascertainment assumptions for the marginal model, we show that unconditional logistic regression (ULR) gives a consistent estimate for βM, and we give a consistent estimator for its covariance matrix. The random effects/CLR approach is simple to use and to interpret, but it can use data only from families containing both affected and unaffected members. The marginal/ULR approach uses data from all individuals, but its variance estimates require special computations. A C program to compute these variance estimates is available at http://www.stanford.edu/dept/HRP/epidemiology. We illustrate these pros and cons by application to data on the effects of parity on ovarian cancer risk in mother/daughter pairs, and use simulations to study the performance of the estimates. Genet Epidemiol 25:177–189, 2003. © 2003 Wiley‐Liss, Inc.
Elasto‐hydrodynamische Simulationstechnik mit integriertem Mischreibungskontakt
Authors: Knoll G.
Published: October 2003

Mit den Entwicklungszielen neuer Konzepte in der Motoren‐ und Antriebstechnik verbunden ist die Forderung nach immer höherer spezifischer Leistungsdichte. Die sichere Auslegung der Lagerungen erfordert hierbei ein besseres Systemverständnis für Wechselwirkungen, die sich aus tribologischer und konstruktiver Sicht ergeben. Ein Weg zum besseren Systemverständnis ist die Simulationstechnik auf Basis hochauflösender Modelle. Zur Verbesserung der Auslegungssicherheit sowie zur Ausnutzung bisher ungenutzter werkstoff‐ und schmierungstechnischer sowie konstruktiver Optimierungspotentiale wird in der Gleitlagertechnik intensiv an der Entwicklung von Simulationsverfahren gearbeitet, welche – gegenüber den bisherigen Auslegungsverfahren – auch Parameter berücksichtigen, welche für den Übergang und die Intensität von Mischreibungszuständen maßgeblich sind. Aus fluid‐mechanischer Sicht bestimmt die Oberflächenfeingestalt maßgeblich die tribologischen Eigenschaften hinsichtlich der mikrohydrodynamischen Schmierfilmbildung und der mechanischen Beanspruchung im Festkörperkontakt. In dem vorliegenden Beitrag werden Verfahren zur tribologischen Kennwertbildung rauer Oberflächen durch Flusstensoren und durch Kontaktdruckkennfelder sowie deren Integration in elasto‐hydrodynamische Berechnungstechniken vorgestellt. Hieraus abgeleitet wird ein örtliches Konzept zur Ermittlung qualitativer und quantitativer Verschleißzustände. Zur Ermittlung der notwendigen werkstoffspezifischen Kenndaten wurden außermotorische Gleitlagerversuche für unterschiedliche Lager‐ und Wellenwerkstoffe durchgeführt.
Synergistic effects of RAD and Neoral in inhibition of host‐vs.‐graft and graft‐vs.‐host immune responses in rat small‐bowel transplantation
Authors: Johnson Stéphane , Qi Shiji , Xu Dasheng , Jolicoeur Marc , Liu Dingyi , Barama Azemi , Busque Stéphane , Smeesters Christian , Daloze Pierre , Chen Huifang
Published: October 2003

The combined effects of RAD and Neoral were tested in a rat orthotopic small‐bowel transplantation model. Seven groups (n = 6) were involved in this study, and each one was included in three rejection models for the evaluation of host‐vs.‐graft disease (HVG) (LBN‐F1 to LEW), graft‐vs.‐host disease (GVH) (LEW to LBN‐F1), and combined HVG and GVH immune responses (BN to LEW). Both drugs were administered orally throughout the study. Low doses of RAD (1.0–2.5 mg/kg/day) combined with Neoral (2.0–5.0 mg/kg/day) produced strong synergistic effects in the prolongation of small‐bowel graft survival in HVG (combination index, CI = 0.095, 0.1212), GVH (CI = 0.027, 0.020), and combined HVG and GVH immune responses (CI = 0.070, 0.301). The combination therapy of RAD and Neoral produces a strong synergistic effect toward the inhibition of HVG, GVH, and combined HVG and GVH immune responses in a rat small‐bowel transplantation model. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:476–482 2003
Observations of rat ovarian‐splenic consecutive transplants
Authors: Hong I.C. , Lee S. , Yoo C.H. , Nam S. , Bai S. , Kim K. , Pivetti C.D. , Niewiadomski S.T. , Wolf P. , Gittes R.F.
Published: October 2003

We examined the results after implantation of ovarian follicles by various modes in a total of 82 cases. One or five ovarian follicles were implanted into spleens in castrated female rats. In 20 cases among these, each five follicles were implanted into native and transplanted spleens after spleen transplantation (double implantation of the ovary). Through consecutive spleen transplantation, we observed the results beyond the rat's life span for a limited period. In many cases, we found a more aggressive form of malignant tumor, i.e., dysgerminoma. We present the results and discuss the modes of implantations and possible pathogenetic mechanisms of tumor formation. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:450–453 2003
Effect of annealing on the electrical properties and morphology of a conducting polymer used as an anode in organic light‐emitting devices
Authors: Kim W. H. , Kushto G. P. , Kim H. , Kafafi Z. H.
Published: October 2003

The surface sheet resistance of conducting films of glycerol‐doped poly(3,4‐ethylenedioxy‐thiophene)–poly(styrene sulfonate) is largely dependent on the annealing temperature. The presence of free glycerol in insufficiently baked films, as indicated by infrared spectra and thermogravimetric analysis, results in conducting polymer films with poor morphology and low electrical conductivity. The device performance of organic light‐emitting diodes using this modified poly(3,4‐ethylenedioxy‐thiophene)–poly(styrene sulfonate) as an anode is also greatly affected by the baking conditions of the conducting films. The maximum light output, current density, and luminous power efficiency are observed from devices using anodes baked at a high temperature close to the boiling point of glycerol. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2522–2528, 2003
New materials for optical rectification and electrooptic sampling of ultrashort pulses in the terahertz regime
Authors: Hayden L. Michael , Sinyukov Alexander M. , Leahy Megan R. , French Joey , Lindahl Peter , Herman Warren N. , Twieg Robert J. , He Meng
Published: October 2003

The synthesis and nonlinear optical characterization of new electrooptic (EO) materials useful for terahertz (THz) applications is presented. Semiempirical calculations were used to guide the development of a series of chromophores on the basis of 2‐dicyanomethylen‐3‐cyano‐4,5,5‐trimethyl‐2,5‐dihydrofuran acceptors acting as guests in polymer films used in the generation of THz radiation via optical rectification. Amorphous films, 65–250 μm thick, with EO coefficients as high as 52 pm/V at 785 nm were used to generate sub‐picosecond pulses with bandwidths up to 3 THz. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2492–2500, 2003
Field effect conductance of conducting polymer nanofibers
Authors: Merlo Jeffrey A. , Frisbie C. Daniel
Published: October 2003

We report on the electrical conductance of nanofibers of regioregular poly(3‐hexylthiophene) (RRP3HT) as a function of gate‐induced charge. Nanofibers of RRP3HT were deposited onto SiO2/Si substrates by casting from dilute p‐xylene solutions. An analysis of the nanofibers by atomic force microscopy revealed fiber lengths of 0.2–5 μm, heights of 3–7 nm, and widths of approximately 15 nm. A field effect transistor geometry was used to probe the conductance of webs of nanofibers and single nanofibers; in these measurements, gold electrodes served as source and drain contacts, and the doped SiO2/Si substrate served as the gate. Temperature‐dependent transport studies on webs of nanofibers revealed an activation energy of 108 meV at a gate‐induced hole density of 3.8 × 1012 charges/cm2. Pretreating SiO2 with a hydrophobic hexamethyldisilazane (HMDS) layer reduced the activation energy to 65 meV at the same charge density. The turn‐on gate voltage on treated and untreated substrates increased in magnitude with decreasing temperature. Conductance measurements on single nanofibers on HMDS‐treated SiO2 yielded hole mobilities as high as 0.06 cm2/Vs with on/off current ratios greater than 103. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2674–2680, 2003
First principles total energy calculations of the adsorption of single Cl2 and Br2 molecules on the Si(001)‐c(2 × 4) surface
Authors: Takeuchi Noboru
Published: October 2003

We have performed first principles total energy calculations to investigate the adsorption of Cl2 and Br2 molecules on the Si(001)‐c(2 × 4) surface. First of all, our results indicate that the adsorption of Cl2 and Br2 as molecules is not energetically favorable. Instead, Cl2 (Br2) dissociates into two Cl (Br) subunits. The most stable geometry was achieved when each Cl (Br) subunit is bonded to a Si atom of the same Si dimer along the dangling bonds. Three other geometries were considered in our study: the first one corresponds to adsorption of the two subunits on Si dimer sites in adjacent silicon dimer rows. The second corresponds to adsorption of the two Cl (Br) subunits along dangling bonds of two consecutive dimers of the same Si dimer row, with the two Cl(Br) atoms in the same side of the Si dimer row. The third one is similar to the second, but the ad‐atoms are now in a staggered arrangement, occupying sites in opposite sides of the Si dimer row. These are adsorption configurations that have been observed experimentally for Cl2 on Si(001). Our results indicate that energetics and atomic geometries are similar for Cl2 and Br2. We have also calculated energy barriers for the ad‐atom to move along and across the Si dimer rows. It is found that the barriers for Br are smaller than the barriers for Cl. This result can explain the differences observed in the adsorption of Cl2 and Br2 molecules.
On crystal‐field parametrization in a uniformly strained crystal lattice
Authors: Mulak J.
Published: October 2003

The general consequences of uniform strain of a crystal lattice or coordination complex in phenomenological parametrization of the crystal‐field potential are considered. The analysis is based on the three‐dimensional derivatives of intrinsic crystal‐field parameters within the superposition model of the crystal‐field potential. The problem of the lowest possible symmetry of a uniformly strained crystal is discussed. Some limitations of the admissible deformations arise from the invariance of symmetry planes and inversion centre with respect to uniform strains. For any uniform strain, the crystal‐field potentials that are expressible by q‐even terms only can never be reduced to potentials requiring q‐odd terms. Therefore, their maximal symmetry lowering must terminate at a monoclinic point symmetry group. However, for a general uniform strain, some real derivatives of parameters of orthorhombic character IIk2 for 2 ≤ k ≤ 6, apart from the axial ones Bk0 for 1 ≤ k≤ 6, can always occur. As a consequence, the decrease in symmetry for point groups that are characterized by an odd‐fold axis (q‐odd) and lack of any symmetry plane is unrestricted down to the triclinic systems. However, some incomplete sets of crystal‐field parameters compared with those predicted by group theory are needed. Uniform strains in crystals occur generally as a response to external stress used in pressure studies. The calculation method of the relative dimensionless changes of dBkq/Bkq as a function of pressure using the stress–strain data (elastic stiffness moduli) is given. Such successful calculations for the Pr3+ : LiYF4 system based only on the crystallographic data and the tk exponents (in the distance dependence of Bkq) are presented as an example. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Oxygen diffusion in YSZ single crystals at relatively low temperatures
Authors: Röwer Ralf , Knöner Gregor , Reimann Klaus , Schaefer Hans‐Eckhardt , Södervall Ulf
Published: October 2003

The 18O tracer experiments were carried out on two cubic YSZ single crystals at temperatures of TD = 423 K and TD = 473 K. The diffusion profiles were determined by the SIMS technique. The diffusion coefficients, the surface exchange coefficients and the activation enthalpy are discussed together with earlier data at higher temperatures. The present oxygen diffusion data demonstrate that the same diffusion process is operating over a wide temperature range. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multi‐frequency EPR studyof Cr3+ doped lead titanate (PbTiO3) nanopowders
Authors: Erdem Emre , Böttcher Rolf , Semmelhack Hans‐Christoph , Gläsel Hans‐Jürgen , Hartmann Eberhard
Published: October 2003

In our multi‐frequency EPR study of Cr3+ doped PbTiO3 nanopowder samples with varying mean particle size, three paramagnetic Cr3+ centres (C1, C2, C3) with different axial fine structure (FS) parameters are identified, with one of them (C1) being compatible with former literature measurements on bulk and ceramics samples carried out in the X band. The superposition model by Newman and Urban was applied to translate the FS data into local displacements inside the distorted oxygen octahedra of the PbTiO3 lattice. When going to nanopowder samples with mean particle size below a critical value, other than the centre C1 are no longer detectable. Instead, a new one (C4) appears, testifying a pronounced size effect. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heuristics and Problem Solving
Authors: Abel Charles F.
Published: October 2003

Heuristics often play a valuable role in solving problems. In this chapter, the author offers a problem‐solving model that employs various general heuristics that may be tailored for specific applications across disciplines.
Schizophrenia: Putting context in context
Authors: Park Sohee , Lee Junghee , Folley Bradley , Kim Jejoong
Published: October 2003

Although context-processing deficits may be core features of schizophrenia, context remains a poorly defined concept. To test Phillips & Silverstein's model, we need to operationalize context more precisely. We offer several useful ways of framing context and discuss enhancing or facilitating schizophrenic patients' performance under different contextual situations. Furthermore, creativity may be a byproduct of cognitive uncoordination.
Phenomenology, context, and self-experience in schizophrenia
Authors: Sass Louis A. , Uhlhaas Peter J.
Published: October 2003

Impairments in cognitive coordination in schizophrenia are supported by phenomenological data that suggest deficits in the processing of visual context. Although the target article is sympathetic to such a phenomenological perspective, we argue that the relevance of phenomenological data for a wider understanding of consciousness in schizophrenia is not sufficiently addressed by the authors.
Combating fuzziness with computational modeling
Authors: Talamini L. M. , Meeter M. , Murre J. M. J.
Published: October 2003

Phillips & Silverstein's ambitious link between receptor abnormalities and the symptoms of schizophrenia involves a certain amount of fuzziness: No detailed mechanism is suggested through which the proposed abnormality would lead to psychological traits. We propose that detailed simulation of brain regions, using model neural networks, can aid in understanding the relation between biological abnormality and psychological dysfunction in schizophrenia.
Color as a factor analytic approximation to Nature
Authors: Reeves Adam
Published: October 2003

Color vision provides accurate measures of the phase and intensity of daylight, and also a means of discriminating between objects. Neither property implies that objects are colored.
UPPER FIRST-EXIT TIMES OF COMPOUND POISSON PROCESSES REVISITED
Authors: Stadje W. , Zacks S.
Published: October 2003

For a compound Poisson process (CPP) with only positive jumps,
an elegant formula connects the density of the hitting time for a
lower straight line with that of the process itself at time t,
h(x; t), considered as a function
of time and position jointly. We prove an analogous (albeit
more complicated) result for the first time the CPP crosses
an upper straight line. We also consider the conditional density
of the CPP at time t, given that the upper line has
not been reached before t. Finally, it is shown how
to compute certain moment integrals of h.
NOTE ON THE CONVEXITY OF THE STATIONARY WAITING TIME AS A
FUNCTION OF THE DENSITY
Authors: Hordijk Arie , van der Laan Dinard
Published: October 2003

It is proved that the total average waiting time is a convex
function of the routing densities for regular routing to parallel
queues.
LEGITIMACY, DEMOCRACY, AND RAZIAN AUTHORITY
Authors: Hershovitz Scott
Published: October 2003

Joseph Raz has developed a highly detailed analysis of the nature of authority that accounts for its structure, the role it plays in practical reasoning, and the conditions under which it is legitimate. Raz's analysis, which has been evolving over the last few decades, is impressive in both scope and insight. With it, Raz dissolves many of the paradoxes and conundrums that have traditionally puzzled students of authority.
Pixel‐scale composite top‐of‐the‐atmosphere clear‐sky reflectances for Meteosat‐7 visible data
Authors: Ipe A. , Clerbaux N. , Bertrand C. , Dewitte S. , Gonzalez L.
Published: October 2003

A new method to estimate composite top of the atmosphere (TOA) visible clear‐sky reflectances for wide narrow band geostationary satellites such as the Meteosat constellation is presented. This method relies on some a priori knowledge of angular variations of TOA broadband reflectances associated with clear‐sky conditions above mean surface types through the use of the clear‐sky Cloud and the Earth's Radiant Energy System (CERES) shortwave broadband angular dependency models (ADMs). Each pixel (or Earth location) viewed from such geostationary imager at a given daytime is associated with a reflectance time series made up of its chronological daily measurements. This time series can be seen as a clear‐sky visible narrow band reflectance curve of the associated pixel surface plus an additive random noise modeling cloudy conditions above it. On the basis of this assumption, TOA clear‐sky broadband reflectances extracted from the CERES ADMs are used to compute curve‐driven fifth percentiles on these time series in order to estimate the TOA clear‐sky visible narrow band reflectance curves for all pixels, while the percentile approach exhibits only a reduced sensitivity to cloud shadows. Benefits of our method are discussed with respect to its application to 7 months of Meteosat‐7 daytime visible narrow band measurements. Finally, the performance of our algorithm is assessed through comparisons with its predicted and associated International Cloud Climatology Project DX clear‐sky values with respect to a visually generated clear‐sky pixels database.